Mechanosensing and anesthesia of single internodal cells of Chara

The giant (2-3 × 10-2 m long) internodal cells of the aquatic plant, Chara, exhibit a rapid (>100 × 10-6 m s-1) cyclic cytoplasmic streaming which stops in response to mechanical stimuli. Since the streaming - and the stopping of streaming upon stimulation - is easily visible with a stereomicroscope, these single cells are ideal tools to investigate mechanosensing in plant cells, as well as the potential for these cells to be anesthetized. We found that dropping a steel ball (0.88 × 10-3 kg, 6 × 10-3 m in diameter) through a 4.6 cm long tube (delivering ca. 4 × 10-4 J) reliably induced mechanically-stimulated cessation of cytoplasmic streaming. To determine whether mechanically-induced cessation of cytoplasmic streaming in Chara was sensitive to anesthesia, we treated Chara internodal cells to volatilized chloroform in a 9.8 × 10-3 m3 chamber for 2 minutes. We found that low doses (15,000-25,000 ppm) of chloroform did not always anesthetize cells, whereas large doses (46,000 and higher) proved lethal. However, 31,000 ppm chloroform completely, and reversibly, anesthetized these cells in that they did not stop cytoplasmic streaming upon mechanostimulation, but after 24 hours the cells recovered their sensitivity to mechanostimulation. We believe this single-cell model will prove useful for elucidating the still obscure mode of action of volatile anesthetics.

A Multifunctional Dehalobacter? Tandem Chloroform and Dichloromethane Degradation in a Mixed Microbial Culture

Chloroform (CF) and dichloromethane (DCM) contaminate groundwater sites around the world but can be cleaned up through bioremediation. Although several strains of Dehalobacter restrictus can reduce CF to DCM and multiple Peptococcaceae can ferment DCM, these processes cannot typically happen simultaneously due to CF sensitivity in the known DCM-degraders or electron donor competition. Here, we present a mixed microbial culture that can simultaneously metabolize CF and DCM and create an additional enrichment culture fed only DCM. Through genus-specific quantitative polymerase chain reaction, we find that Dehalobacter grows while either CF alone or DCM alone is converted, indicating its involvement in both metabolic steps. Additionally, the culture was maintained for over 1400 days without the addition of an exogenous electron donor, and through electron balance calculations, we show that DCM metabolism would produce sufficient reducing equivalents (likely hydrogen) for CF respiration. Together, these results suggest intraspecies electron transfer could occur to continually reduce CF in the culture. Minimizing the addition of electron donor reduces the cost of bioremediation, and "self-feeding" could prolong bioremediation activity long after donor addition ends. Overall, understanding this mechanism informs strategies for culture maintenance and scale-up and benefits contaminated sites where the culture is employed for remediation worldwide.

Cytotoxicity and genotoxicity evaluation of chloroform using Vicia faba roots

Chloroform is a widely used industrial chemical that can also pollute the environment. The aims of this study were to examine the potential cytotoxicity and genotoxicity of chloroform on plant cells, using the Vicia faba bioassay. Chloroform was evaluated at concentrations of 0.1, 0.5, 1, 2, and 5 mg·L-1. The following parameters were analyzed: the mitotic index (MI), micronucleus (MN) frequency, chromosomal aberration (CA) frequency, and malondialdehyde (MDA) content. The results showed that exposure to increasing concentrations of chloroform caused a decrease in MI and an increase in the frequency of MN in Vicia faba root tip cells, relative to their controls. Moreover, various types of CA, including C-mitosis, fragments, bridges, laggard chromosomes, and multipolar mitosis, were observed in the treated cells. The frequency of MN was positively correlated with the frequency of CA in exposure to 0.1-1 mg·L-1 chloroform. Furthermore, chloroform exposure induced membrane lipid peroxidation damage in the Vicia faba radicle, and a linear correlation was observed between the MDA content and the frequency of MN or CA. These findings indicated that chloroform exposure can result in oxidative stress, cytotoxicity, and genotoxicity in plant cells.

Anthropogenic Chloroform Emissions from China Drive Changes in Global Emissions

Emissions of chloroform (CHCl3), a short-lived halogenated substance not currently controlled under the Montreal Protocol on Substances that Deplete the Ozone Layer, are offsetting some of the achievements of the Montreal Protocol. In this study, emissions of CHCl3 from China were derived by atmospheric measurement-based "top-down" inverse modeling and a sector-based "bottom-up" inventory method. Top-down CHCl3 emissions grew from 78 (72-83) Gg yr-1 in 2011 to a maximum of 193 (178-204) Gg yr-1 in 2017, followed by a decrease to 147 (138-154) Gg yr-1 in 2018, after which emissions remained relatively constant through 2020. The changes in emissions from China could explain all of the global changes during the study period. The CHCl3 emissions in China were dominated by anthropogenic sources, such as byproduct emissions during disinfection and leakage from chloromethane industries. Had emissions continued to grow at the rate observed up to 2017, a delay of several years in Antarctic ozone layer recovery could have occurred. However, this delay will be largely avoided if global CHCl3 emissions remain relatively constant in the future, as they have between 2018 and 2020.

Chloroform exposure in air and water in Swedish indoor swimming pools-urine as a biomarker of occupational exposure

INTRODUCTION

Disinfection by-products are produced in water disinfected with chlorine-based products. One such group is trihalomethanes, and chloroform is the most abundant trihalomethane in swimming pool areas. Chloroform can be absorbed by inhalation, ingestion, and dermal absorption, and is classified as possibly carcinogenic.

AIM

To investigate if chloroform concentrations in air and water affect the chloroform concentration in urine samples of exposed swimming pool workers.

METHODS

Workers from 5 adventure indoor swimming pools carried personal chloroform air samplers and provided up to 4 urine samples during one workday. Chloroform concentrations were analyzed with a linear mixed model analysis to investigate a possible correlation between air and urine concentrations.

RESULTS

The geometric mean chloroform concentration was 11 μg/m3 in air and 0.009 µg/g creatinine in urine among individuals with ≤2 h at work, 0.023 µg/g creatinine among those with >2-5 working hours, and 0.026 µg/g creatinine in the group with >5-10 working hours. A risk of higher levels of chloroform in urine was associated with longer hours at work (≤2 h versus >5-10 h, odds ratio [OR] 2.04, 95% confidence interval [CI] 1.25-3.34), personal chloroform concentrations in air (≤17.00 µg/m3 versus >28.00 µg/m3, OR 9.23, 95% CI 3.68-23.13) and working at least half the working day near the swimming pools (OR 3.16, 95% CI 1.33-7.55). Executing work tasks in the swimming pool water was not associated with higher chloroform concentrations in urine compared to only working on land (OR 0.82, 95% CI 0.27-2.45).

CONCLUSION

There is an accumulation of chloroform concentrations in urine during a workday and a correlation between personal air and urine concentrations of chloroform among workers in Swedish indoor swimming pools.

Efficient and Reversible Separation of Chloroform from Chlorinated Hydrocarbons and Water Utilizing a Two-Dimensional Coordination Network

Chloroform is a volatile organic solvent and a contaminant that is slightly soluble in water, making the reversible separation of chloroform from water a critical and challenging task within the chemical and environmental industries. In this study, we present a newly developed coordination framework, [Zn(4-pmntd)(opa)] [4-pmntd, N,N'-bis(4-pyridylmethyl)naphthalene diimide; opa, o-phthalic acid], which demonstrates a high adsorption capacity for chloroform (2.5 mmol/g) and an excellent ability to separate chloroform from water. The effectiveness of chloroform extraction by Zn(4-pmntd)(opa) was confirmed through vapor sorption, grand canonical Monte Carlo simulation, and 1H nuclear magnetic resonance spectroscopy. The porous framework was also utilized to create a filtration film using natural rubber, which successfully separated chloroform from water with a minimum test concentration of approximately 1 × 10-6 mol/L and a chloroform purity of 99.2%. [Zn(4-pmntd)(opa)] therefore has significant potential for low-energy separation and recycling of chloroform from water under ambient conditions.

Degradation of Chloroform by Zerovalent Iron: Effects of Mechanochemical Sulfidation and Nitridation on the Kinetics and Mechanism

Chloroform (CF) is a widely used chemical reagent and disinfectant and a probable human carcinogen. The extensive literature on halocarbon reduction with zerovalent iron (ZVI) shows that transformation of CF is slow, even with nano, bimetallic, sulfidated, and other modified forms of ZVI. In this study, an alternative method of ZVI modification─involving simultaneous sulfidation and nitridation through mechanochemical ball milling─was developed and shown to give improved degradation of CF (i.e., higher degradation rate and inhibited H₂ evolution reaction). The composite material (denoted as S-N(C)-ZVI) gave synergistic effects of nitridation and sulfidation on CF degradation. A complete chemical reaction network (CRN) analysis of CF degradation suggests that O-nucleophile-mediated transformation pathways may be the main route for the formation of the terminal nonchlorinated products (formate, CO, and glycolic polymers) that have been used to explain the undetected products needed for mass balance. Material characterizations of the ZVI recovered after batch experiments showed that sulfidation and nitridation promoted the formation of Fe₃O₄ on the S-N(C)-ZVI particles, and the effect of aging on CF degradation rates was minor for S-N(C)-ZVI. The synergistic benefits of sulfidation and nitridation on CF degradation were also observed in experiments performed with groundwater.

Extraction Solvents Affect Anthocyanin Yield, Color, and Profile of Strawberries

Anthocyanins are a major group of plant pigments that have antioxidant activities. Pigments play a major role in human health and have attracted a lot of attention globally. Many factors affect anthocyanin yields, such as solvent type, incubation time, solvent-to-sample ratio, sample type, and temperature. The first parameter was tested, and the rest were considered constant in this experiment. A total of nine organic and water-based solvents (methanol and chloroform: methanol, acetone, ethanol, water) and their combinations were compared to extract anthocyanins from freshly-pureed strawberries. Solvents changed anthocyanin yield, color parameters, and profile. The color parameters of a* values lower than 30, L* values higher than 85, hue angle more than 40, and chroma less than 30 indicated some color degradation in strawberry anthocyanins. Therefore, the best solvents for anthocyanin assessment were methanol and methanol: water. The second-best solvent was the pH differential buffers. Other solvents such as ethanol, chloroform: methanol, water, and water-based solvents extracted considerable amounts of anthocyanins; however, they showed some degree of color degradation, evidenced by the color parameters. Acetone did not yield a stable extract which degraded over 48 h of storage at 4 °C. The extraction solvent determined the main anthocyanin of the anthocyanins profile. Pelargonidin was the major anthocyanin in chloroform: methanol solvent, while delphinidin was dominant in all other solvents.

Ergosterol extraction: a comparison of methodologies

Ergosterol is a component of the cell membrane of mycorrhizal fungi and is frequently used to quantify their biomass. Arbuscular mycorrhizal (AM) fungi and ectomycorrhizal (ECM) fungi establish a symbiotic relationship with a respective host plant. Several methods are currently employed for quantification of ergosterol; however, these utilise a series of potentially hazardous chemicals with varying exposure times to the user. The present comparative study aims to ascertain the most reliable method to extract ergosterol whilst limiting hazard exposure to the user. Chloroform, cyclohexane, methanol and methanol hydroxide extraction protocols were applied to a total of 300 samples of root samples and a further 300 growth substrate samples across all protocols. Extracts were analysed via HPLC methodologies. Chromagraphic analysis showed chloroform-based extraction procedures produced a consistently higher concentration of ergosterol in both root and growth substrate samples. Methanol hydroxide, without the addition of cyclohexane, produced a very low concentration of ergosterol, with a reduction of quantified ergosterol of between 80 and 92 % compared to chloroform extractions. Hazard exposure was greatly reduced following the chloroform extraction protocol when compared with other extraction procedures.

The Use of Volatile Substances in Drug-Facilitated Sexual Assault: A Systematic Review

Drug-facilitated sexual assault (DFSA) is a significant crime that is increasing in incidence. The employment of volatile substances such as chloroform and aromatic petroleum hydrocarbons in DFSAs is quite an unusual choice. The objective of this review is to explore the use of volatile substances in DFSAs. Using the PubMed database, a systematic review of the literature was conducted. Thereafter, citation searching was carried out within the included studies from the primary search. A total of five studies were eligible for inclusion. Chloroform was the drug used in the DFSA in three of the included studies, and aromatic hydrocarbons in the remaining two. Two of the offenders who employed chloroform possessed a unique way to access the drug: their degrees. The evidence found in the DFSA cases included a chloroform-scented scarf and a solvent-immersed cloth. Headspace gas chromatography-mass spectrometry, liquid chromatography-electrospray coupled tandem mass spectrometry, toxicology assays of blood and urine, and solvent or hydrocarbon gas chromatography flame-ionization detection followed by gas chromatography-mass spectrometry were among the investigations performed to detect the volatile substances. The implementation of stricter regulations on chloroform for employees in chemical industries and laboratories is recommended. In cases where the autopsy is unclear and there are conspicuous facial and airway injuries, it is prudent to collect an early sample for volatile substance analysis.

Hyperpolarization Induced by Lipopolysaccharides but Not by Chloroform Is Inhibited by Doxapram, an Inhibitor of Two-P-Domain K+ Channel (K2P)

Bacterial septicemia is commonly induced by Gram-negative bacteria. The immune response is triggered in part by the secretion of bacterial endotoxin lipopolysaccharide (LPS). LPS induces the subsequent release of inflammatory cytokines which can result in pathological conditions. There is no known blocker to the receptors of LPS. The Drosophila larval muscle is an amendable model to rapidly screen various compounds that affect membrane potential and synaptic transmission such as LPS. LPS induces a rapid hyperpolarization in the body wall muscles and depolarization of motor neurons. These actions are blocked by the compound doxapram (10 mM), which is known to inhibit a subtype of the two-P-domain K+ channel (K2P channels). However, the K2P channel blocker PK-THPP had no effect on the Drosophila larval muscle at 1 and 10 mM. These channels are activated by chloroform, which also induces a rapid hyperpolarization of these muscles, but the channels are not blocked by doxapram. Likewise, chloroform does not block the depolarization induced by doxapram. LPS blocks the postsynaptic glutamate receptors on Drosophila muscle. Pre-exposure to doxapram reduces the LPS block of these ionotropic glutamate receptors. Given that the larval Drosophila body wall muscles are depolarized by doxapram and hyperpolarized by chloroform, they offer a model to begin pharmacological profiling of the K2P subtype channels with the potential of identifying blockers for the receptors to mitigate the actions of the Gram-negative endotoxin LPS.

Are Endodontic Solvents Cytotoxic? An In Vitro Study on Human Periodontal Ligament Stem Cells

The aim of this study was to assess the influence of eucalyptol, chloroform, and Endosolv on the proliferative capability, cell viability, and migration rates of human periodontal ligament stem cells (hPDLSCs) in vitro. Solvent eluates were formulated following ISO 10993-5 guidelines, and 1%, 0.25%, and 0.1% dilutions were prepared. The HPDLSCs were isolated from the extracted third molars of healthy donors. The following parameters were assessed: cell viability via trypan blue and IC50 assays, cell migration via horizontal wound healing assay, cell morphology via cell cytoskeleton staining (phalloidin labeling), and cell oxidative stress via reactive oxygen species assay. The data were analyzed using one-way ANOVA and Tukey’s posthoc tests, and their significance was established at p < 0.05. Chloroform and eucalyptol exhibited significantly higher cytotoxicity on the hPDLSCs in vitro compared to the control group, as shown by the cell viability, migration, morphology, and reactive oxygen species release assays. Alternatively, Endosolv showed adequate cytotoxicity levels comparable to those of the control group. The cytotoxicity of the tested endodontic solvents increased in a dose-dependent manner. The results from the present study highlight the cytotoxicity of chloroform and eucalyptol. Thus, their limited and cautious use is recommended, avoiding solvent extrusion.

Organic Vapor Sensing Mechanisms by Large-Area Graphene Back-Gated Field-Effect Transistors under UV Irradiation

The gas sensing properties of graphene back-gated field-effect transistor (GFET) sensors toward acetonitrile, tetrahydrofuran, and chloroform vapors were investigated with the focus on unfolding possible gas detection mechanisms. The FET configuration of the sensor device enabled gate voltage tuning for enhanced measurements of changes in DC electrical characteristics. Electrical measurements were combined with a fluctuation-enhanced sensing methodology and intermittent UV irradiation. Distinctly different features in 1/f noise spectra for the organic gases measured under UV irradiation and in the dark were observed. The most intense response observed for tetrahydrofuran prompted the decomposition of the DC characteristic, revealing the photoconductive and photogating effect occurring in the graphene channel with the dominance of the latter. Our observations shed light on understanding surface processes at the interface between graphene and volatile organic compounds for graphene-based sensors in ambient conditions that yield enhanced sensitivity and selectivity.

Exposure to Chloramine and Chloroform in Tap Water and Adverse Perinatal Outcomes in Shanghai

Chloramine and chloroform are widespread in tap water due to water disinfection processes. This study was designed to explore the associations between trimester-specific exposure to chloramine and chloroform in tap water and adverse outcomes. This retrospective cohort study included 109,182 mother–infant singleton pairs in Shanghai. A logistic regression model was used to evaluate the associations of chloramine and chloroform concentrations averaged over the whole pregnancy and in each trimester with adverse outcomes, including gestational diabetes mellitus (GDM), gestational hypertensive disorders (GHD), low birthweight (LBW), small for gestational age (SGA), preterm birth (PTB) and prelabor rupture of membranes (PROM). The use of tap water with elevated chloramine levels in the first trimester was associated with GDM (OR = 1.06, 95% CI: 1.03, 1.09), while that in the second trimester was related to GHD (OR = 1.13, 95% CI: 1.09, 1.17). Chloroform levels in the third trimester were associated with LBW (OR = 1.13, 95% CI: 1.09, 1.16), PTB (OR = 1.05, 95% CI: 1.01, 1.08) and PROM (OR = 1.01, 95% CI: 1.00, 1.01). However, tap water chloroform exposure in the second trimester was negatively associated with LBW (OR = 0.95, 95% CI: 0.93, 0.98) and PTB (OR = 0.97, 95% CI: 0.94, 0.99). In conclusion, there are probably no casual associations between current tap water chloroform and chloramine levels and perinatal outcomes. However, more research focusing on the effect of chloramine and chloroform on perinatal outcomes are still warranted.

Functionalization of Glucose Oxidase in Organic Solvent: Towards Direct Electrical Communication across Enzyme-Electrode Interface

Enzymatic biosensors based on glucose oxidase has been proven to be one of the effective strategies for the detection of glucose and contributed to health improvements. Therefore, research and debates to date are ongoing in an attempt to find the most effective way to detect this analyte using this enzyme as the recognition center. The 3rd generation biosensors using direct electron transfer (DET) type enzymes are a great way towards practical devices. In this work, we developed a simple method for the functionalization of glucose oxidase with redoxable ferrocene groups in chloroform. The enzyme retained its activity after storage in this organic solvent and after the functionalization procedures. This enzyme functionalization strategy was employed to develop the biosensing monolayer-based platforms for the detection of glucose utilizing the quasi-DET mechanism. As a result of an electrochemical regeneration of the catalytic center, the formation of harmful H₂O₂ is minimized during enzymatic electrocatalysis.

Direct Syntheses of Diphenylmethanol Derivatives from Substituted Benzenes and CHCl3 through Friedel-Crafts Alkylation and Post-Synthetic Hydrolysis or Alcoholysis Catalyzed by Alumina

The present study reports an innovative finding that alumina containing water or primary alcohol catalyzes the hydrolysis or alcoholysis, respectively, of the product formed through AlCl3 -mediated Friedel-Crafts alkylation of methyl-substituted benzenes and CHCl3 . The former and later reactions mainly provided hydroxy- and alkoxy-substituted diarylmethanes, respectively, while the reference reactions without alumina provided bisarylchloromethane. This method enables the selective syntheses of diphenylmethanol derivatives with very simple procedures, without expensive reagents and apparatuses. Furthermore, the alumina used in the reaction could be recycled by washing with water and subsequent drying. From the viewpoint of material recycling, this function is very important for the development of sustainable chemical reactions.

Temporal and spatial variations in the levels of prominent airborne disinfection by-products at four indoor swimming pools

Exposure to airborne disinfection by-products, especially trichloramine and trichloromethane, may cause various adverse health effects for the workers and users of indoor swimming pools. This study aims to evaluate the spatial and temporal variations in trichloramine and trichloromethane concentrations within and between swimming pools. Workplace measurements were carried out at four indoor swimming pools in Quebec (Canada) during the cold season. To fully represent daily operating conditions, sampling started 2 hr before the swimming pool opened and continued until 2 hr after closing. To quantify trichloramine and trichloromethane concentrations, 304 air samples have been collected. Temperature, humidity, and CO₂ were measured-simultaneously every 2 hr. The results showed that both trichloramine and trichloromethane concentrations varied significantly in time. The observed daily variations in trichloramine and trichloromethane concentrations suggest that the common practice of collecting a single 2-hr air sample does not represent daily pool trichloramine and trichloromethane contamination levels and, consequently, does not represent the true exposure and health risks for workers that are present for a full 8-hr shift. This study recommends a new 8-hr sampling strategy or a full-shift strategy using a cassette with three impregnated filters as a valid and cost-effective solution for comparing time-weighted average (TWA) concentrations to permissible trichloramine exposure limits.

Degradation Characteristics of Carbon Tetrachloride by Granular Sponge Zero Valent Iron

Granular sponge zero valent iron (ZVI) was employed to degrade carbon tetrachloride (CCl₄). The effects of acidic washing, initial solution pH, and ZVI dosage on CCl₄ degradation were investigated. Results showed that CCl₄ was effectively removed by ZVI and approximately 75% of CCl₄ was transformed into chloroform through hydrogenolysis. The rate of chloroform transformation was slower compared to that of CCl₄, resulting in chloroform accumulation. CCl₄ degradation was a pseudo first-order process. The observed pseudo first-order reaction rate constant (k_obs) for CCl₄ and chloroform were 0.1139 and 0.0109 h⁻¹, respectively, with a ZVI dosage of 20 g/L and an initial CCl₄ concentration of 20 mg/L. Surface acidic washing had a negligible effect on CCl₄ degradation with ZVI. The k_obs for CCl₄ degradation increased linearly with increasing ZVI dosage and the optimal dosage of ZVI was 20 g/L based on the surface area-normalized rate constants. The negative relationship between k_obs and the solution pH indicated that the degradation of CCl₄ by ZVI performed better under weakly acidic conditions.

Using genome comparisons of wild-type and resistant mutants of Methanococcus maripaludis to help understand mechanisms of resistance to methane inhibitors

Methane emissions from enteric fermentation in the ruminant digestive system generated by methanogenic archaea are a significant contributor to anthropogenic greenhouse gas emissions. Additionally, methane produced as an end-product of enteric fermentation is an energy loss from digested feed. To control the methane emissions from ruminants, extensive research in the last decades has been focused on developing viable enteric methane mitigation practices, particularly, using methanogen-specific inhibitors. We report here the utilization of two known inhibitors of methanogenic archaea, neomycin and chloroform, together with a recently identified inhibitor, echinomycin, to produce resistant mutants of Methanococcus maripaludis S2 and S0001. Whole-genome sequencing at high coverage (> 100-fold) was performed subsequently to investigate the potential targets of these inhibitors at the genomic level. Upon analysis of the whole-genome sequencing data, we identified mutations in a number of genetic loci pointing to potential mechanisms of inhibitor action and their underlying mechanisms of resistance.

Charles and Emma Darwin: Under the 'influence' of chloroform anaesthesia

A number of Charles Darwin's biographies record the administration of chloroform by Darwin to his wife Emma, during her labour and delivery of her eighth child, Leonard. This occurred on 15 January 1850, a little over two years after James Young Simpson in Edinburgh described the analgesic action of inhaled chloroform. An online search of more than 9000 items of Darwin's correspondence at Cambridge University and other sources revealed that he was an active proponent and user of chloroform in midwifery, for euthanising animals he studied, as well as in botanical studies of carnivorous plants. He also discovered that the concurrent inhalation of chloroform, during its administration to his wife, alleviated his distressing anxiety which he suffered when present at her earlier confinements.

The Effects of Various Final Irrigants on the Bond Strength of Root Dentin Exposed to Chloroform: An In vitro Study

Aim:

The aim of the study was to assess the reaction of different final irrigants to the bond strength of root dentin exposed to chloroform.

Materials and Methods:

Fifty extracted maxillary central incisors were selected. Working length was determined, and canal was instrumented with ProTaper rotary system (Dentsply Maillefer) till F4 file. The specimens were then divided into five groups (n = 10). Group 1: not disclosed to any root canal solvent, Group 2: disclosed to chloroform for 5 min, Group 3: chloroform for 5 min followed by absolute alcohol, Group 4: chloroform for 5 min followed by chlorhexidine (CHX), And Group 5 – chloroform for 5 min followed by saline. The canals were obturated with F4 gutta-percha cones with AH Plus sealer. The samples will be sectioned horizontally into 1 ± 0.1 mm thick slices. The push-out bond strength was performed in a universal testing machine. Results were statistically analyzed by one-way analysis of variance.

Results:

There existed a significant difference between the mean push-out bond strength of different groups. Irrigation with chloroform negatively affected the bonding between root canal sealer and root dentine. Absolute alcohol significantly improved the bond strength values.

Conclusion:

Exposure with chloroform during the retreatment will decrease the bonding between sealer (AH Plus) and root dentine. The use of absolute alcohol as a final irrigant improved the bonding between sealer and dentin. CHX and saline showed no improvement in bond strength.

John Davies Thomas: Chloroformist in London and pioneer South Australian doctor

John Davies Thomas (1844-1893) described a two-ounce drop-bottle for chloroform in 1872 while he was a resident medical officer at University College Hospital, London. After working as a ship's surgeon, he settled in Australia. In May 1875, Thomas presented a paper on the mortality from ether and chloroform at a meeting of the Medical Society of Victoria in Melbourne, Victoria. Surveys conducted in Europe and North America had established that the mortality from chloroform was eight to ten times higher than that from ether. At that time, chloroform was the most widely administered anaesthetic in Australia. Thomas' paper was published in The Australian Medical Journal and reprinted by the Medical Society of Victoria for distribution to hospitals in the Colony of Victoria. Later that year, Thomas moved to Adelaide, South Australia, where he may have been influential at the Adelaide Hospital in ensuring that ether was administered more often than chloroform. It does not appear that Thomas' papers on anaesthesia had a significant effect on the conduct of anaesthesia in Victoria or New South Wales.

Mutagenicity Assessment to Pesticide Adjuvants of Toluene, Chloroform, and Trichloroethylene by Ames Test

Pesticide adjuvants (PAs) denote the general term for auxiliaries in pesticide preparations except for the active components. Toluene, chloroform, and trichloroethylene are the three most commonly used PAs as organic solvents. The residues of the three chemicals in the process of production and application of pesticides may endanger the ecosystem. In the present study, the mutagenicity of toluene, chloroform, and trichloroethylene as well the mixture of the three chemicals was tested by the Salmonella typhimurium reverse mutation test (Ames test) with TA97, TA98, TA100, and TA102 strains in the system with and without rat liver microsomal preparations (S9). The four tester strains have been used for more than 40 years to detect mutagenic compounds in chemicals, cosmetics, and environmental samples. The mutagenicity was detected on tester strains in the separated experiment from the three chemicals. The addition of S9 decreased the mutation ratios of toluene to four strains, except for the TA100 strain, but increased the mutation ratios of chloroform to four strains except for the TA98 strain. Trichloroethylene caused positive mutagenicity to become negative on the TA102 strain. In the mixed experiment, positive effects were detected only on the TA102 strain in the absence of S9. The addition of S9 increased the mutagenicity except for the TA102 strain. The mixture of toluene, chloroform, and trichloroethylene showed antagonism in mutagenicity to tester strains, except for the TA102 strain without S9. However, the mixture showed a synergistic effect to tester strains after adding S9 except for the TA98 strain.

The 115 Year Old Multicomponent Bargellini Reaction: Perspectives and New Applications

Despite its uniqueness, the Bargellini multicomponent reaction remains barely known by the most part of chemists. This can be ascribed to the fact that this transformation has not been adequately reviewed in the classic books of named reactions in organic chemistry. Nevertheless, several works on this reaction have been carried out over the years, many of them were written in Italian in the period 1929-1966. In this review article we extensively cover, in a chronological order, the most important applications of the Bargellini reaction reported to date, with the hope that this knowledge-sharing will help chemists to properly use this multicomponent transformation and imagine novel reactivities based on it.

A laboratory study to assess the formation of effluent volatile compounds and disinfection by-products during chemomechanical preparation of infected root canals and application of activated carbon for their removal

AIM

To assess in a laboratory setting using extracted teeth the formation of volatile compounds (VOCs) and disinfection by-products (DBPs) in effluent aliquots, during chemomechanical preparation of artificially infected root canal specimens, and determine the role of silver-impregnated activated carbon (Ag-AC) in their removal.

METHODOLOGY

Single-rooted human teeth were decoronated to obtain 15 mm-long root specimens and a nutrient-stressed multispecies biofilm was grown in the root canals. Specimens were randomly assigned into three groups [Group 1; instrumentation with rotary files and irrigation with sterile saline, Groups 2 and 3; instrumentation with rotary files and irrigation with 2.5% NaOCl and 17% EDTA]. A portable medical suction device was used to collect the effluent aliquots during root canal irrigation. In Groups 1 and 2, the reaction products of the collected effluents were analysed by selected ion flow tube mass spectrometry (SIFT-MS). The effluents from Group 3 were treated with Ag-AC prior to SIFT-MS analysis, to assess the removal capacity of Ag-AC against the reaction products. The synthesis of Ag-AC was characterized with scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS). Two-way analysis of variance (anova) with post hoc Tukey tests was used for data analysis and determination of a significant difference (P < 0.05).

RESULTS

In Group 1, effluent VOCs and DBPs were detectable at very low levels. In Group 2, the collected effluent aliquots released high concentrations of methanol, propanol, ammonia, chloroform and formaldehyde, which were significantly greater compared to Group 1 (P < 0.001). SEM/EDS analysis confirmed impregnation of Ag within the AC matrix. The treatment of effluent aliquots with Ag-AC (Group 3) resulted in a significant reduction in concentrations of acetone, acetic acid, propanol, acetaldehyde, acetonitrile and chloroform, compared to Group 2 (P < 0.001). The concentration levels of ethanol, methanol, ammonia and formaldehyde remained unaffected (P > 0.05).

CONCLUSIONS

In this laboratory setting using extracted human teeth, the chemomechanical preparation of artificially infected root canals resulted in the formation of toxic VOCs and DBPs as effluent suspensions. Their release during aspiration with dental suction indicates that potential environmental hazards should be investigated. The use of silver-impregnated activated carbon had potential for the point-of-use treatment of post-irrigation effluent aliquots.

The use of solvents for gutta-percha dissolution/removal during endodontic retreatments: A scoping review

This scoping review study aimed to map the evidence about solvents' use for gutta-percha dissolution and removal during endodontic retreatments. The study protocol followed the Joanna Briggs Institute guidelines, available online (https://osf.io/5vy8n/). Reporting was based on PRISMA Extension for Scoping Reviews. We selected dentistry studies that considered the effectiveness of solvents in gutta-percha dissolution in endodontic retreatments and compared their performance to the use of instrumentation techniques without solvents. The search and study screening were performed in PubMed and Scopus databases by two independent researchers. A descriptive analysis considered the study design, method/technique used for obturation, method/technique used for instrumentation during retreatment, solvent solutions tested, exposure time, and main findings. A total of 41 studies were included. Despite that, most studies suggested that solvents' use may complicate root canal cleanliness, regardless of the type of instrumentation used, and facilitate the presence of gutta-percha remnants in the root surface. Thus, the use of solvents should be avoided and its use should only be considered if the previous working length was not possible to access without it. Despite that, high heterogeneity was observed, further studies are still encouraged comparing the performance and effects of different solvents in different clinical scenarios.

Efficient Removal of Non-Structural Protein Using Chloroform for Foot-and-Mouth Disease Vaccine Production

To differentiate foot-and-mouth disease (FMD)-infected animals from vaccinated livestock, non-structural proteins (NSPs) must be removed during the FMD vaccine manufacturing process. Currently, NSPs cannot be selectively removed from FMD virus (FMDV) culture supernatant. Therefore, polyethylene glycol (PEG) is utilized to partially separate FMDV from NSPs. However, some NSPs remain in the FMD vaccine, which after repeated immunization, may elicit NSP antibodies in some livestock. To address this drawback, chloroform at a concentration of more than 2% (v/v) was found to remove NSP efficiently without damaging the FMDV particles. Contrary to the PEG-treated vaccine that showed positive NSP antibody responses after the third immunization in goats, the chloroform-treated vaccine did not induce NSP antibodies. In addition to this enhanced vaccine purity, this new method using chloroform could maximize antigen recovery and the vaccine production time could be shortened by two days due to omission of the PEG processing phase. To our knowledge, this is the first report to remove NSPs from FMDV culture supernatant by chemical addition. This novel method could revolutionize the conventional processes of FMD vaccine production.

Metagenomic- and Cultivation-Based Exploration of Anaerobic Chloroform Biotransformation in Hypersaline Sediments as Natural Source of Chloromethanes

Chloroform (CF) is an environmental contaminant that can be naturally formed in various environments ranging from forest soils to salt lakes. Here we investigated CF removal potential in sediments obtained from hypersaline lakes in Western Australia. Reductive dechlorination of CF to dichloromethane (DCM) was observed in enrichment cultures derived from sediments of Lake Strawbridge, which has been reported as a natural source of CF. No CF removal was observed in abiotic control cultures without artificial electron donors, indicating biotic CF dechlorination in the enrichment cultures. Increasing vitamin B₁₂ concentration from 0.04 to 4 µM in enrichment cultures enhanced CF removal and reduced DCM formation. In cultures amended with 4 µM vitamin B₁₂ and ¹³C labelled CF, formation of ¹³CO₂ was detected. Known organohalide-respiring bacteria and reductive dehalogenase genes were neither detected using quantitative PCR nor metagenomic analysis of the enrichment cultures. Rather, members of the order Clostridiales, known to co-metabolically transform CF to DCM and CO₂, were detected. Accordingly, metagenome-assembled genomes of Clostridiales encoded enzymatic repertoires for the Wood-Ljungdahl pathway and cobalamin biosynthesis, which are known to be involved in fortuitous and nonspecific CF transformation. This study indicates that hypersaline lake microbiomes may act as a filter to reduce CF emission to the atmosphere.

Global optimization of the Michaelis-Menten parameters using physiologically-based pharmacokinetic (PBPK) modeling and chloroform vapor uptake data in F344 rats

Objective: To quantify metabolism, a physiologically based pharmacokinetic (PBPK) model for a volatile compound can be calibrated with the closed chamber (i.e. vapor uptake) inhalation data. Here, we introduce global optimization as a novel component of the predictive process and use it to illustrate a procedure for metabolic parameter estimation.Materials and methods: Male F344 rats were exposed in vapor uptake chambers to initial concentrations of 100, 500, 1000, and 3000 ppm chloroform. Chamber time-course data from these experiments, in combination with optimization using a chemical-specific PBPK model, were used to estimate Michaelis-Menten metabolic constants. Matlab^® simulation software was used to integrate the mass balance equations and to perform the global optimizations using MEIGO (MEtaheuristics for systems biology and bIoinformatics Global Optimization - Version 64 bit, R2016A), a toolbox written for Matlab®. The cost function used the chamber time-course data and least squares to minimize the difference between data and simulation values.Results and discussion: The final values estimated for V_max (maximum metabolic rate) and K_m (affinity constant) were 1.2 mg/h and a range between 0.0005 and 0.6 mg/L, respectively. Also, cost function plots were used to analyze the dose-dependent capacity to estimate V_max and K_m within the experimental range used. Sensitivity analysis was used to assess identifiability for both parameters and show these kinetic data may not be sufficient to identify K_m.Conclusion: In summary, this work should help toxicologists interested in optimization techniques understand the overall process employed when calibrating metabolic parameters in a PBPK model with inhalation data.

William Osler and the "fixed period" of creativity

In 1905, William Osler was the pre-eminent physician in American medical circles but was unknown to the general public. The latter suddenly learned of him through damning newspaper accounts of his address announcing his retirement from the Johns Hopkins Medical School. In it Osler mentioned two "fixed ideas" he held-(1) that most major advances in civilization have been made by men under age 40 (the "fixed period") and (2) that those over 60 should retire because they create little of significance and sometimes stifled the initiatives of younger colleagues. He highlighted the second idea with a Victorian novel describing a mythical society which chloroformed men at age 60. He never imagined that this literary allusion would be taken as a serious solution for his second idea. However, countless newspaper articles ridiculed the first and condemned him for the second. Scurrilous press attacks on him continued for several months and resurfaced occasionally thereafter. The extent of the public approbation can also be found in poems and stories linking him with euthanasia. Also discussed here are the sources of Osler's equanimity in the face of such public derision and the inner drives which accounted for over 1300 publications by him-nearly half of which were composed after age 40.

Radicals and Ions Formed in Plasma-Treated Organic Solvents: A Mechanistic Investigation to Rationalize the Enhancement of Electrospinnability of Polycaprolactone

This paper reports and discusses the beneficial effects on the quality of electrospun polycaprolactone nanofibers brought about by pretreatment of the solvent with non-thermal plasma. Chloroform/dimethylformamide 9:1 (CHCl₃:DMF 9:1) and pure chloroform were pretreated by a few minute exposure to the plasma generated by an atmospheric pressure plasma jet (APPJ). Interestingly, when pure chloroform was used, the advantages of plasma pretreatment of the solvent were way less pronounced than found with the CHCl₃:DMF 9:1 mixture. The chemical modifications induced by the plasma in the solvents were investigated by means of complementary analytical techniques. GC-MS revealed the formation of solvent-derived volatile products, notably tetrachloroethylene (C₂Cl₄), 1,1,2,2-tetrachloroethane (C₂H₂Cl₄), pentachloroethane (C₂HCl₅), hexachloroethane (C₂Cl₆) and, in the case of the mixed solvent, also N-methylformamide (C₂H₅NO). The chlorinated volatile products are attributed to reactions of ·Cl and Cl-containing methyl radicals and carbenes formed in the plasma-treated solvents. ·Cl and ·CCl₃ radicals were detected and identified by EPR spectroscopy analyses. Ion chromatography revealed the presence of Cl^-, NO 3 - , and HCOO^- (the latter only in the presence of DMF) in the plasma-treated solvents, thus accounting for the observed increased conductivity and acidification of the solvent after plasma treatment. Mechanisms for the formation of these solvent derived products induced by plasma are proposed and discussed. The major role of radicals and ions in the plasma chemistry of chloroform and of the chloroform/dimethylformamide mixture is highlighted. The results provide insight into the interaction of plasma with organic solvents, a field so far little explored but holding promise for interesting applications.

Recent Trends in Stratospheric Chlorine From Very Short-Lived Substances

Very short-lived substances (VSLS), including dichloromethane (CH2Cl2), chloroform (CHCl3), perchloroethylene (C2Cl4), and 1,2-dichloroethane (C2H4Cl2), are a stratospheric chlorine source and therefore contribute to ozone depletion. We quantify stratospheric chlorine trends from these VSLS (VSLCltot) using a chemical transport model and atmospheric measurements, including novel high-altitude aircraft data from the NASA VIRGAS (2015) and POSIDON (2016) missions. We estimate VSLCltot increased from 69 (±14) parts per trillion (ppt) Cl in 2000 to 111 (±22) ppt Cl in 2017, with >80% delivered to the stratosphere through source gas injection, and the remainder from product gases. The modeled evolution of chlorine source gas injection agrees well with historical aircraft data, which corroborate reported surface CH2Cl2 increases since the mid-2000s. The relative contribution of VSLS to total stratospheric chlorine increased from ~2% in 2000 to ~3.4% in 2017, reflecting both VSLS growth and decreases in long-lived halocarbons. We derive a mean VSLCltot growth rate of 3.8 (±0.3) ppt Cl/year between 2004 and 2017, though year-to-year growth rates are variable and were small or negative in the period 2015-2017. Whether this is a transient effect, or longer-term stabilization, requires monitoring. In the upper stratosphere, the modeled rate of HCl decline (2004-2017) is -5.2% per decade with VSLS included, in good agreement to ACE satellite data (-4.8% per decade), and 15% slower than a model simulation without VSLS. Thus, VSLS have offset a portion of stratospheric chlorine reductions since the mid-2000s.

Green synthesis, characterisation and biological evaluation of plant-based silver nanoparticles using Quercus semecarpifolia Smith aqueous leaf extract

The development of reliable and green methods for the fabrication of metallic nanoparticles (NPs) has many advantages in the field of nanotechnology. In this direction, the present work describes an eco-friendly and cost-effective protocol for the production of silver NPs (AgNPs) using an aqueous extract of Quercus semecarpifolia leaves. Different techniques were carried out for the characterisation of the synthesised AgNPs. The ultraviolet-visible spectroscopic analysis showed the highest absorbance peak at 430 nm. The particle size and structure were confirmed by scanning electron microscopy as well as transmission electron microscopy (TEM) analysis. From TEM imaging, it was revealed that the formed particles were spherical with an average size of 20-50 nm. The crystalline nature of the NPs was determined by X-ray powder diffraction patterns. Thermogravimetry and differential thermal analysis were also evaluated by a temperature increment from 100 to 1000°C. Bio-inspired synthesis of AgNPs was performed for their pharmacological evaluation in relation to the activities of the crude methanolic, n-hexane, chloroform, ethyl acetate, and aqueous extracts. Good cytotoxic activity was exhibited by the green-synthesised AgNPs (77%). Furthermore, the AgNPs were found to exhibit significant antioxidant activity at 300 μg/ml (82%). The AgNPs also exhibited good phytotoxic potential (75%).

Vapoluminescent Behavior and the Single-Crystal-to-Single-Crystal Transformations of Chloroform Solvates of [Au2 (μ-1,2-bis(diphenylarsino)ethane)2 ](AsF6 )2

The mono- and di-chloroform solvates of [Au₂ (μ-1,2-bis(diphenylarsino)ethane)₂ ](AsF₆ )₂ undergo single-crystal-to-single-crystal transformations that result in gain (over 12 hours) or slow loss (over five years) of only one chloroform molecule. The change in solvation results in changes in the structure and luminescence of the digold cation. The cation consists of a pair of slightly bent As-Au-As units that are connected through the two bridging dpae ligands and by aurophilic interactions with Au⋅⋅⋅Au contacts of 3.05152(15) Å in the disolvate or 2.9570(5) Å in the monosolvate.

Impact of chloroform exposures on reproductive and developmental outcomes: A systematic review of the scientific literature

AIMS

We assessed the animal and epidemiological data to determine if chloroform exposure causes developmental and/or reproductive toxicity.

RESULTS AND DISCUSSION

Initial scoping identified developmental toxicity as the primary area of concern. At levels producing maternal toxicity in rats and mice, chloroform caused decrements in fetal weights and associated delays in ossification. In a single mouse inhalation study, exposure to a high concentration of chloroform was associated with small fetuses and increased cleft palate. However, oral exposure of mice to chloroform at a dose 4 times higher was negative for cleft palate; multiple inhalation studies in rats were also negative. Epidemiologic data on low birth weight and small for gestational age were generally equivocal, preventing conclusions from being drawn for humans. The animal data also show evidence of very early (peri-implantation) total litter losses at very high exposure levels. This effect is likely maternally mediated rather than a direct effect on the offspring. Finally, the epidemiologic data indicate a possible association of higher chloroform exposure with lower risk of preterm birth (<37 weeks gestation).

CONCLUSIONS

The available animal data suggest that exposures lower than those causing maternal toxicity should be without developmental effects in the offspring. Also, most studies in humans rely on group-level geographic exposure data, providing only weak epidemiologic evidence for an association with development outcomes and fail to establish a causal role for chloroform in the induction of adverse developmental outcomes at environmentally relevant concentrations.

3-NOP vs. Halogenated Compound: Methane Production, Ruminal Fermentation and Microbial Community Response in Forage Fed Cattle

The aim of this study was to investigate the effects of 3-nitrooxypropanol (3-NOP) and chloroform on methane (CH₄) and H₂ production, ruminal metabolites and microbial community structure in cattle fed a tropical forage diet. Eight rumen-fistulated steers were fed a roughage hay diet (Rhodes grass; Chloris gayana) for 31 days (control period). Four animals received the antimethanogenic compound chloroform (1.6 g chloroform-cyclodextrin/100 kg live weight (LW)) while the other four received 3-NOP (2.5 g 3-NOP/animal/day) for 21 days. Methane decrease compared with control period was similar for both treatments (30-38%) with no differences for expelled H₂ between controls and treatments. Daily weight gain (DWG) was significantly increased when animals were treated with 3-NOP compared with chloroform and control. Regarding the ruminal fermentation parameters increases in ammonia, acetate and branched chain fatty acids were observed with both compounds compared with the controls. Also, methylamines, alcohols and dimethyl sulfone (DMSO₂) concentrations were significantly increased with the treatments compared with control, being greater with 3-NOP. The rumen microbial analyses revealed a similar profile for both treatments, with a shift in operational taxonomic units (OTUs) assigned to the Prevotellaceae and Campylobacteraceae family. Moreover, major archaeal OTUs associated with Methanobrevibacter and Methanosphaera were significantly affected to varying extents based on the inhibitory treatments compared to the control. The abundance of the Methanobrevibacter spp. was decreased by 3-NOP and chloroform, while the Methanomassiliicoccaceae family was inhibited only by 3-NOP. The results suggest that despite the specific mode of action of 3-NOP on methanogens, inhibition of methanogenesis by both compounds resulted in similar responses in metabolism and microbial community structure in the rumen. We hypothesized that these changes were driven by the redirection of metabolic hydrogen ([H]) by both treatments. Therefore results from previous publications using chloroform as an inhibitor of methanogenesis may be useful in predicting ruminal microbiota and fermentation responses to 3-NOP.

Effect of TiO2/GAC and water vapor on chloroform decomposition in a hybrid plasma-catalytic system

This paper presents the combination of TiO₂/GAC catalyst and NTP for the decomposition of chloroform using a DBD reactor. The experiments were performed using an AC transformer as the power supply system to determine the optimal conditions of the chloroform conversion in the presence of a hydrogen-rich substance, that is, water vapor. TiO₂/GAC enhanced the removal efficiency and also CO₂ selectivity significantly, leading to an acceptable conversion rate at SIEs higher than 400 J L^-1. The adsorption property of GAC was noticed to be an effective factor for catalytic activity by increasing the residence time, although the higher retention time prevented the accurate determination of chlorine and carbon balance. Selectivity toward HCl was improved considerably from 24.3% to 64.3% over catalyst when water was fed as a hydrogen-rich compound. At the same time, the harmful chlorinated by-products such as TCBA and TCE declined significantly. A noticeable enhancement in the selectivity toward CO₂ was observed when both catalyst and water were introduced, regardless of the inlet concentration. Our findings suggest that the hybrid of NTP with TiO₂/GAC will highly be effective in the abatement of chloroform, and the addition of H₂O will successfully decline harmful chlorinated by-products.

Exposure to disinfectant by-products and the risk of stillbirth in Massachusetts

OBJECTIVES

We examined stillbirths in relation to disinfection by-product (DBP) exposures including chloroform, bromodichloromethane (BDCM), dibromochloromethane, bromoform, trichloroacetic acid, dichloroacetic acid (DCAA), monobromoacetic acid and summary DBP measures (trihalomethanes (THM4), haloacetic acids (HAA5), THMBr (brominated trihalomethanes) and DBP9 (sum of THM4 and HAA5)).

METHODS

We randomly selected 10 controls for each of the 2460 stillbirth cases with complete quarterly 1997-2004 THM4 and HAA5 town-level drinking water data. Adjusted (aORs) were calculated based on weight-averaged second-trimester DBP exposures.

RESULTS

We detected statistically significant associations for stillbirths and the upper DCAA quartiles (aOR range: 1.50-1.71). We also found positive associations for the upper four HAA5 quintiles and different stillbirth cause of death categories that were examined including unexplained stillbirth (aOR range: 1.24-1.72), compression of umbilical cord (aOR range: 1.08-1.94), prematurity (aOR range: 1.37-2.88), placental separation and haemorrhage (aOR range: 1.44-2.01) and asphyxia/hypoxia (aOR range: 1.52-1.97). Additionally, we found positive associations between stillbirths and chloroform exposure (aOR range: 1.29 - 1.36) and unexplained stillbirths and BDCM exposure (aOR range: 1.51 - 1.78). We saw no evidence of exposure-response relationships for any categorical DBP metrics.

CONCLUSIONS

Consistent with some previous studies, we found associations between stillbirths and chloroform and unexplained stillbirth and BDCM exposures. These findings strengthen existing evidence of prenatal THM exposures increasing the risk of stillbirth. Additionally, we saw statistically significant associations between DCAA and stillbirth. Future research should examine cause-specific stillbirths in relation to narrower critical windows and additional DBP exposure metrics beyond trihalomethanes and haloacetic acids.

Biomass Extraction Using Non-Chlorinated Solvents for Biocompatibility Improvement of Polyhydroxyalkanoates

An economically viable method to extract polyhydroxyalkanoates (PHAs) from cells is desirable for this biodegradable polymer of potential biomedical applications. In this work, two non-chlorinated solvents, cyclohexanone and γ-butyrolactone, were examined for extracting PHA produced by the bacterial strain Cupriavidus necator H16 cultivated on vegetable oil as a sole carbon source. The PHA produced was determined as a poly(3-hydroxybutyrate) (PHB) homopolyester. The extraction kinetics of the two solvents was determined using gel permeation chromatography (GPC). When cyclohexanone was used as the extraction solvent at 120 °C in 3 min, 95% of the PHB was recovered from the cells with a similar purity to that extracted using chloroform. With a decrease in temperature, the recovery yield decreased. At the same temperatures, the recovery yield of γ-butyrolactone was significantly lower. The effect of the two solvents on the quality of the extracted PHB was also examined using GPC and elemental analysis. The molar mass and dispersity of the obtained polymer were similar to that extracted using chloroform, while the nitrogen content of the PHB extracted using the two new solvents was slightly higher. In a nutshell, cyclohexanone in particular was identified as an expedient candidate to efficiently drive novel, sustainable PHA extraction processes.

Hazards of Improper Dispensary: Literature Review and Report of an Accidental Chloroform Injection

Several clear, transparent solutions are used in endodontics. Inappropriate dispensing methods can lead to accidental injection or accidental irrigation. These accidents can cause permanent tissue damage including damage to the bone, periodontium, nerves, and vasculature. This article reports on the consequences of an accidental chloroform injection. Nonsurgical retreatment of tooth #8 was planned as part of a restorative treatment plan in a 69-year-old woman. The dentist accidentally injected chloroform instead of local anesthesia because chloroform was loaded into the anesthetic syringe. The patient experienced severe pain and swelling and soft tissue necrosis and suffered permanent sensory and motor nerve damage. A review of the literature was performed on accidents caused by improper dispensary, namely accidental injections and accidental irrigations. The data were extracted and summarized. Sodium hypochlorite, chlorhexidine, formalin, formocresol, 1:1000 adrenaline, benzalkonium chloride, and lighter fuel were accidentally injected as an intraoral nerve block or as infiltration injections. Bone and soft tissue necrosis, tooth loss, and sensory nerve damage (anesthesia and paresthesia) were the most common consequences reported. Such disastrous events can be prevented by appropriate labeling and separate dispensing methods for each solution. There is a need for disseminating information on toxicity and biocompatibility of materials/solutions used in endodontics. The authors recommend training dental students and endodontic residents on immediate and long-term therapeutic management of patients when an accidental injection or accidental irrigation occurs.

MALDI-TOF MS for the Identification of Cultivable Organic-Degrading Bacteria in Contaminated Groundwater near Unconventional Natural Gas Extraction Sites

Groundwater quality and quantity is of extreme importance as it is a source of drinking water in the United States. One major concern has emerged due to the possible contamination of groundwater from unconventional oil and natural gas extraction activities. Recent studies have been performed to understand if these activities are causing groundwater contamination, particularly with respect to exogenous hydrocarbons and volatile organic compounds. The impact of contaminants on microbial ecology is an area to be explored as alternatives for water treatment are necessary. In this work, we identified cultivable organic-degrading bacteria in groundwater in close proximity to unconventional natural gas extraction. Pseudomonas stutzeri and Acinetobacter haemolyticus were identified using matrix-assisted laser desorption/ionization-time-of-flight-mass spectrometry (MALDI-TOF MS), which proved to be a simple, fast, and reliable method. Additionally, the potential use of the identified bacteria in water and/or wastewater bioremediation was studied by determining the ability of these microorganisms to degrade toluene and chloroform. In fact, these bacteria can be potentially applied for in situ bioremediation of contaminated water and wastewater treatment, as they were able to degrade both compounds.

Chloroform alters interleaflet coupling in lipid bilayers: an entropic mechanism

The interaction of the two leaflets of the plasmatic cell membrane is conjectured to play an important role in many cell processes. Experimental and computational studies have investigated the mechanisms that modulate the interaction between the two membrane leaflets. Here, by means of coarse-grained molecular dynamics simulations, we show that the addition of a small and polar compound such as chloroform alters interleaflet coupling by promoting domain registration. This is interpreted in terms of an entropic gain that would favour frequent chloroform commuting between the two leaflets. The implication of this effect is discussed in relation to the general anaesthetic action.

(1)H NMR spectra of alcohols in hydrogen bonding solvents: DFT/GIAO calculations of chemical shifts

Proton nuclear magnetic resonance (NMR) shifts of aliphatic alcohols in hydrogen bonding solvents have been computed on the basis of density functional theory by applying the gauge-including atomic orbital method to geometry-optimized alcohol/solvent complexes. The OH proton shifts and hydrogen bond distances for methanol or ethanol complexed with pyridine depend very much on the functional employed and very little on the basis set, provided it is sufficiently large to give the correct quasi-linear hydrogen bond geometry. The CH proton shifts are insensitive to both the functional and the basis set. NMR shifts for all protons in several alcohol/pyridine complexes are calculated at the Perdew, Burke and Ernzerhof PBE0/cc-pVTZ//PBE0/6-311 + G(d,p) level in the gas phase. The results correlate with the shifts for the pyridine-complexed alcohols, determined by analysing data from the NMR titration of alcohols against pyridine. More pragmatically, computed shifts for a wider range of alcohols correlate with experimental shifts in neat pyridine. Shifts for alcohols in dimethylsulfoxide, based on the corresponding complexes in the gas phase, correlate well with the experimental values, but the overall root mean square difference is high (0.23 ppm), shifts for the OH, CHOH and other CH protons being systematically overestimated, by averages of 0.42, 0.21 and 0.06 ppm, respectively. If the computed shifts are corrected accordingly, a very good correlation is obtained with a gradient of 1.00 ± 0.01, an intercept of 0.00 ± 0.02 ppm and a root mean square difference of 0.09 ppm. This is a modest improvement on the result of applying the CHARGE programme to a slightly different set of alcohols. Some alcohol complexes with acetone and acetonitrile were investigated both in the gas phase and in a continuum of the relevant solvent.

Liquid-State Structure via Very High-Field Nuclear Magnetic Resonance Discriminates among Force Fields

Deuterium nuclear magnetic resonance ((2)H NMR) spectra of labeled molecular liquids obtained at high fields, for example, |B| = 22.3 T (950 MHz proton NMR), exhibit resolved quadrupolar splittings that reflect the average orientation of the molecules relative to B. Those residual nuclear spin interactions exhibited by benzene and chloroform provide an experimental determination of the leading tensor component of the pair correlation function for these two molecular liquids. In this way, very high-field (2)H NMR may be used to extract unambiguous information about liquid-state structure. Additionally, replicating the experimentally derived pair correlation function using molecular dynamics simulations provides a critical test of simulation force fields.

Developments in labour analgesia and their use in Australia

Since the introduction of chloroform for labour analgesia in 1847, different methods and medications have been used to relieve the pain of labour. The use of heavy sedative medication in the early 1900s was encouraged by enthusiastic doctors and by women empowered by the women's suffrage movement in America. Nitrous oxide by inhalation has been used in Australia since the 1950s and improved methods of administration have made this method of analgesia safe and practical. Caudal epidural analgesia and lumbar epidural analgesia were first made popular in America and by the 1970s these techniques were more widely available in Australia. In 1847, physicians and the public were unsure whether relieving labour pains was the 'right' thing to do. However, many medical and social changes have occurred thanks to the clinical connection between Australia and the United Kingdom and those first settlers to land on Australian shores. Thanks to this historical connection, in today's Australia there is no question that women should use analgesia as a pain relief if they wish. Currently, the majority of women worldwide use some form of analgesia during labour and different methods are widely available. This paper discusses the four milestones of the development of obstetric analgesia and how they were introduced into patient care in Australia.

Formation of chloroform and tetrachloroethene by Sinorhizobium meliloti strain 1021

The mechanisms and organisms involved in the natural formation of volatile organohalogen compounds (VOX) are largely unknown. We provide evidence that the common and widespread soil bacterium Sinorhizobium meliloti strain 1021 is capable of producing up to 3338·6 ± 327·8 ng l(-1) headspace volume of chloroform (CHCl3 ) and 807·8 ± 13·5 ng l(-1)  headspace volume of tetrachloroethene (C2 Cl4 ) within 1 h when grown in soil extract medium. Biotic VOX formation has been suggested to be linked to the activity of halogenating enzymes such as haloperoxidases. We tested if the observed VOX formation by S. meliloti can be attributed to one of its chloroperoxidases (Smc01944) that is highly expressed in the presence of H2 O2. However, addition of 10 mmol l(-1) H2 O2 to the S. meliloti cultures decreased VOX formation by 52% for chloroform and 25% for tetrachloroethene, while viable cell numbers decreased by 23%. Interestingly, smc01944 gene expression increased 450-fold. The quantification of extracellular chlorination activity in cell suspension experiments did not provide evidence for a role of S. meliloti chloroperoxidases in the observed VOX formation. This suggests that a momentarily unknown mechanism which requires no H2 O2 might be responsible for the VOX formation by S. meliloti. Regardless of the underlying mechanism our results suggest that the soil bacterium S. meliloti might be an important source of VOX in soils.

SIGNIFICANCE AND IMPACT OF THE STUDY

Volatile organohalogen compounds (VOX) strongly influence atmospheric chemistry and Earth's climate. Besides anthropogenic emissions they are naturally produced by either abiotic or biotic pathways in various environments. Particularly in soils, microbial processes drive the natural halogen cycle but the direct link to microbial VOX formation has not been studied in detail yet. In this study we provide evidence that the common and widespread soil bacterium Sinorhizobium meliloti strain 1021 forms chloroform and tetrachloroethene. The potential contribution of S. meliloti to soil VOX release could significantly influence soil and atmospheric chemistry.

Disinfection of bore well water with chlorine dioxide/sodium hypochlorite and hydrodynamic cavitation

The effect of hydrodynamic cavitation (HC) on potable water disinfection of chemicals was investigated. The bore well water was introduced into HC set-up to examine the effect of HC alone and combination of HC and chemicals such as chlorine dioxide and sodium hypochlorite. The effect of inlet pressure and geometrical parameters on disinfection was studied using HC alone and the results showed that increasing inlet pressure and using more and bigger holes of orifice plates can result in a higher disinfection rates. When HC was combined with chemicals, HC can reduce the doses of the chemicals and shorten the time of disinfection. It was also found that the decrease in bacteria concentration followed a first-order kinetic model. As for the experiment of combination of HC and sodium hypochlorite for disinfection, HC not only improves the disinfection rate but also degrades natural organic matter and chloroform. Compared with only sodium hypochlorite disinfection, combined processes get higher disinfection rate and lower production of chloroform, particularly the pretreatment with HC enhances the disinfection rate by 32% and there is a simultaneous reduction in production of chloroform by 39%.

1H NMR spectra of alcohols and diols in chloroform: DFT/GIAO calculation of chemical shifts

Proton nuclear magnetic resonance (NMR) shifts of aliphatic alcohols in chloroform have been computed on the basis of density functional theory, the solvent being included by the integral-equation-formalism polarisable continuum model of Gaussian 09. Relative energies of all conformers are calculated at the Perdew, Burke and Ernzerhof (PBE)0/6-311+G(d,p) level, and NMR shifts by the gauge-including atomic orbital method with the PBE0/6-311+G(d,p) geometry and the cc-pVTZ basis set. The 208 computed CH proton NMR shifts for 34 alcohols correlate very well with the experimental values, with a gradient of 1.00 ± 0.01 and intercept close to zero; the overall root mean square difference (RMSD) is 0.08 ppm. Shifts for CH protons of diols in chloroform are well correlated with the theoretical values for (isotropic) benzene, with similar gradient and intercept (1.02 ± 0.01, -0.13 ppm), but the overall RMSD is slightly higher, 0.12 ppm. This approach generally gives slightly better results than the CHARGE model of Abraham et al. The shifts of unsaturated alcohols in benzene have been re-examined with Gaussian 09, but the overall fit for CH protons is not improved, and OH proton shifts are worse. Shifts of vinyl protons in alkenols are systematically overestimated, and the correlation of computed shifts against the experimental data for unsaturated alcohols follows a quadratic equation. Splitting the 20 compounds studied into two sets, and applying empirical scaling based on the quadratic for the first set to the second set, gives an RMSD of 0.10 ppm. A multi-standard approach gives a similar result.

Resolubilization of precipitated intact membrane proteins with cold formic acid for analysis by mass spectrometry

Protein precipitation in organic solvent is an effective strategy to deplete sodium dodecyl sulfate (SDS) ahead of MS analysis. Here we evaluate the recovery of membrane and water-soluble proteins through precipitation with chloroform/methanol/water or with acetone (80%). With each solvent system, membrane protein recovery was greater than 90%, which was generally higher than that of cytosolic proteins. With few exceptions, residual supernatant proteins detected by MS were also detected in the precipitation pellet, having higher MS signal intensity in the pellet fraction. Following precipitation, we present a novel strategy for the quantitative resolubilization of proteins in an MS-compatible solvent system. The pellet is incubated at -20 °C in 80% formic acid/water and then diluted 10-fold with water. Membrane protein recovery matches that of sonication of the pellet in 1% SDS. The resolubilized proteins are stable at room temperature, with no observed formylation as is typical of proteins suspended in formic acid at room temperature. The protocol is applied to the molecular weight determination of membrane proteins from a GELFrEE-fractionated sample of Escherichia coli proteins.

Generating viral metagenomes from the coral holobiont

Reef-building corals comprise multipartite symbioses where the cnidarian animal is host to an array of eukaryotic and prokaryotic organisms, and the viruses that infect them. These viruses are critical elements of the coral holobiont, serving not only as agents of mortality, but also as potential vectors for lateral gene flow, and as elements encoding a variety of auxiliary metabolic functions. Consequently, understanding the functioning and health of the coral holobiont requires detailed knowledge of the associated viral assemblage and its function. Currently, the most tractable way of uncovering viral diversity and function is through metagenomic approaches, which is inherently difficult in corals because of the complex holobiont community, an extracellular mucus layer that all corals secrete, and the variety of sizes and structures of nucleic acids found in viruses. Here we present the first protocol for isolating, purifying and amplifying viral nucleic acids from corals based on mechanical disruption of cells. This method produces at least 50% higher yields of viral nucleic acids, has very low levels of cellular sequence contamination and captures wider viral diversity than previously used chemical-based extraction methods. We demonstrate that our mechanical-based method profiles a greater diversity of DNA and RNA genomes, including virus groups such as Retro-transcribing and ssRNA viruses, which are absent from metagenomes generated via chemical-based methods. In addition, we briefly present (and make publically available) the first paired DNA and RNA viral metagenomes from the coral Acropora tenuis.