Analysis of the Distribution of Total Phosphine and the Characteristics of Phosphine Poisoning in 29 Victims

OBJECTIVES

To study the distribution of total phosphine in phosphine poisoning victims and summarize the characteristics of phosphine poisoning cases.

METHODS

The phosphine and its metabolites in the biological samples of 29 victims in 16 phosphine poisoning cases were qualified and quantified by headspace gas chromatography-mass spectrometry.

RESULTS

Five victims among 29 were poisoned by ingestion of aluminium phosphide and 24 by inhalation of phosphine gas. Phosphine metabolites were detected in the biological samples of 23 victims, and the concentrations of total phosphine in blood ranged 0.5-34.0 μg/mL. The total concentration of phosphine in liver tissue was up to 71.0 μg/g. Phosphine was not detected in the blood of the other six survived victims, which may be related to the small amount of phosphine exposure and the delay in blood sampling.

CONCLUSIONS

The total concentration of phosphine in blood and tissues caused by aluminum phosphine ingestion is higher than that caused by phosphine gas inhalation. The death cases of phosphine inhalation are characterized by long exposure time, repeated exposures and age susceptibility.

Rapid trace element analysis of microgram soft materials with cryogenic milling and laser ablation spectroscopy

Trace element analysis of soft materials, to determine the content of low concentration elements, is important in many industries such as food quality control and medical biopsy analysis. Many of these applications would benefit from faster analysis with smaller sample requirements. Further, some natural samples are soft and have high water content, which brings challenges to element analysis. Here, we develop a cryogenic pelletization pretreatment to address those challenges. The soft samples are cryogenically milled, freeze-dried, and pelletized before elemental analysis. Analysis is performed by laser ablation spectroscopy, the combination of laser-induced breakdown spectroscopy (LIBS) and laser ablation inductively coupled plasma mass spectroscopy (LA-ICP-MS), to rapidly analyze light and heavy analytes. For this initial study, aluminum (Al) content in soft samples is determined by LIBS and lead (Pb) content by LA-ICP-MS. The standard addition method is performed to build calibration curves for element quantification. The measurements are compared with a Hong Kong government certified acid digestion and ICP-MS procedure. The experiment is performed on standard reference materials and selected food samples. The relative errors compared with certified measurements are less than 10% for all samples, with Al content ranging from 63-1466 µg/g and Pb content from 0.37-2.35 µg/g (dry mass). Microscopy of pellets shows that laser ablation spectroscopy can be performed with 100 µg of sample (dry mass). Total analysis time from raw sample to final measurement, including preparation, is under 1 h. The results indicate that the laser ablation spectroscopy with cryogenic pelletization is a promising technique for many applications such as screening of small food samples for toxic metals and trace element analysis of millimeter biopsies.

0.25 Ga Salt Deposits Preserve Signatures of Habitable Conditions and Ancient Lipids

Polygonal features in a ∼250 million-year-old Permian evaporitic deposit were investigated for their geological and organic content to test the hypothesis that they could preserve the signature of ancient habitable conditions and biological activity. Investigations on evaporitic rock were carried out as part of the MIne Analog Research (MINAR) project at Boulby Mine, the United Kingdom. The edges of the polygons have a higher clay content and contain higher abundances of minerals such as quartz and microcline, and clays such as illite and chlorite, compared with the interior of polygons, suggesting that the edges were preferred locations for the accumulation of weathering products during their formation. The mineral content and its strontium isotope ratio suggest that the material is from continental weathering at the borders of the Permian Zechstein Sea. The edges of the polygons contain material with mean δ¹³C and δ¹⁵N values of -20.8 and 5.3, respectively. Lipids, including alkanes and hopanes, were extracted from the interior and edges of the polygons, which are inferred to represent organic material entrained in the evaporites when they were formed. The presence of long-chain alkanes (C₂₀-C₃₅) that lack a carbon preference, low abundances of C₂₃-C₂₉ hopanes, and lack of marine, evaporitic, or thermal maturity indicators show that lipid biomarkers were, at least in part, potentially derived from a continental source and have not undergone significant thermal maturation since deposition. Lipid extractions using weak acids revealed significantly more lipids than those without acid, potentially indicating that encapsulation was not the only type of preservation mechanism occurring in Boulby salts. These data demonstrate the potential for ancient evaporites and their polygons to preserve information on local geological conditions, ancient habitability, and evidence of life. The data show that analogous martian evaporitic deposits are good targets for future life detection missions and the investigation of ancient martian habitability.

Phosphine detection in veterinary samples using headspace gas chromatography/tandem mass spectrometry with multiple reaction monitoring

RATIONALE

Determination of phosphine exposure from zinc or aluminum phosphide fumigants continues to be a routine analytical requirement in veterinary forensic toxicology. There is a need for a more reliable and specific method than simple gas chromatography/mass spectrometry (GC/MS) analysis of sample solvent extracts, as GC/MS of extracts on capillary columns used for general screens involves significant interference from air peaks.

METHODS

GC/MS/MS headspace analysis of acid-generated phosphine gas enabled study of the feasibility of devising multiple reaction monitoring (MRM) approaches to the determination of phosphine with greater specificity.

RESULTS

Collision-induced dissociation in GC/MS/MS showed that phosphine generated m/z 34 → 31, 32 and 33 ion transitions by sequential proton release as well as minor transitions m/z 34 → 47, 34 → 63 and 63 → 31.5 by intermolecular collisions and double charging. Study of the formation of these product ions enabled development of MRM settings for a highly useful headspace method for phosphine detection.

CONCLUSIONS

The method was validated over a working range of 5-100 ppm of phosphide generating phosphine gas which enabled retention of regular screen capillary columns without necessitating separation from air components. The method should have adequate sensitivity and reliability for veterinary toxicology laboratories confronting specimens from animals poisoned by crop fumigants.

Chemical Speciation of Aluminum in Wine by LC-ICP-MS

Aluminum is very common in the natural environment and in everyday human life. We are living in the "aluminum age." Its average daily intake should not exceed a few mg/day. Unfortunately, despite the growing number of alarming data about the toxicity of this element, human exposure to aluminum is constantly increasing. The toxicity and bioavailability of aluminum depends mainly on the form in which it occurs. The main variables conditioning the form are the concentration, the type, the molar ratio of aluminum to ligand, the pH value, and the temperature. This research presents a new method for speciation analysis of both inorganic and organic aluminum complexes in model solutions by LC-ICP-MS. Different solutions with variable pH values and different Al/ligand molar ratios (fluorides and several organic ligands, e.g., citrates and oxalates ions) were used. The chromatographic separation process was carried out based on isocratic and gradient elution, using a cation exchange analytical column. All determinations have been confirmed based on chemical equilibrium modeling programs. The new developed method was successfully applied for the first time in speciation analysis of real samples: white and red wine.

Examining a synchrotron-based approach for in situ analyses of Al speciation in plant roots

Aluminium (Al) K- and L-edge X-ray absorption near-edge structure (XANES) has been used to examine Al speciation in minerals but it remains unclear whether it is suitable for in situ analyses of Al speciation within plants. The XANES analyses for nine standard compounds and root tissues from soybean (Glycine max), buckwheat (Fagopyrum tataricum), and Arabidopsis (Arabidopsis thaliana) were conducted in situ. It was found that K-edge XANES is suitable for differentiating between tetrahedral coordination (peak of 1566 eV) and octahedral coordination (peak of 1568 to 1571 eV) Al, but not suitable for separating Al binding to some of the common physiologically relevant compounds in plant tissues. The Al L-edge XANES, which is more sensitive to changes in the chemical environment, was then examined. However, the poorer detection limit for analyses prevented differentiation of the Al forms in the plant tissues because of their comparatively low Al concentration. Where forms of Al differ markedly, K-edge analyses are likely to be of value for the examination of Al speciation in plant tissues. However, the apparent inability of Al K-edge XANES to differentiate between some of the physiologically relevant forms of Al may potentially limit its application within plant tissues, as does the poorer sensitivity at the L-edge.

Assessment of membrane bioreactor fouling with the addition of suspended aluminum nitride nanoparticles

In this study, we assessed fouling in a membrane bioreactor (MBR) with the addition of suspended aluminum nitride (AlN) nanoparticles (NPs). Three parallel laboratory-scale submerged MBRs were operated with 0, 10, and 50 mg AlN NPs/L for over 70 days. The results showed that the addition of suspended AlN NPs did not significantly affect pollutant biodegradation; there was only a slight decrease in NH₄⁺-N removal. Furthermore, the membrane's permeability was increased with effective fouling mitigation by the addition of a high amount of suspended AlN NPs. This was because the suspended AlN NPs decreased the content of polysaccharides in both the extracellular polymeric substances and soluble microbial products, and decreased the sludge floc size. However, the AlN NPs also promoted pore-blocking, particularly standard blocking, which enhanced irreversible fouling. Additionally, owing to the larger ionic radius and higher electronegativity, the AlN NPs inhibited the accumulation of framework components (SiO₂). Therefore, suspended AlN NPs resulted in a thinner cake layer.

Total Recoverable Aluminum: Not Totally Relevant for Water Quality Standards

A large water quality data set, representing more than 100 surface-water locations sampled from 2007 to 2017 in the Los Alamos area of New Mexico, USA's Pajarito Plateau, was assembled to evaluate Al concentrations in unfiltered and filtered samples. Aluminum concentrations often exceeded United States Environmental Protection Agency (USEPA) and New Mexico ambient water quality criteria (AWQC), regardless of filter size and sample location. However, AWQC are based on laboratory toxicity studies using soluble Al salts and do not reflect natural conditions in Pajarito Plateau surface waters. The plateau is predominately covered by glassy and recrystallized volcanic ashes (e.g., Bandelier Tuff) containing colloidal to sand-sized aluminosilicates. Samples from natural background drainages and areas downstream of developed regions exhibited similar Al concentrations, suggesting that AWQC exceedances are caused by naturally elevated Al concentrations. Solubility calculations indicated that most samples were oversaturated with respect to amorphous Al(OH)₃ (s). Therefore, AWQC exceedances are likely artifacts of the "total recoverable" sample preparation, which includes acidification and partial digestion, thereby liberating nonbioavailable Al from aluminosilicates. Accordingly, Al concentrations were strongly associated with suspended sediment concentrations (SSCs), implying that aluminosilicates in suspended sediment contributed to AWQC exceedances and Al oversaturation. Solid-phase particle characterization, using X-ray diffraction (XRD) and scanning electron microscopy with electron dispersive spectroscopy (SEM/EDS) did not identify potentially bioavailable amorphous Al(OH)₃ (s) in any sample tested. Thus, current sample collection and analysis protocols should not be used to evaluate attainment of Al AWQC on the Pajarito Plateau or locations where aluminosilicates are substantial contributors to total recoverable Al. A sample preparation method (e.g., pH 4 extraction) capable of differentiating nonbioavailable and bioavailable forms of Al is recommended. Otherwise, current New Mexico and USEPA sample preparation approaches will continue to generate artifactual AWQC exceedances in surface waters that contain aluminosilicates. Integr Environ Assess Manag 2019;00:1-14. © 2019 SETAC.

Characterization of drilling waste from shale gas exploration in Central and Eastern Poland

The purpose of this research was to determine and evaluate the chemical properties of drilling waste from five well sites in Central and Eastern Poland. It was found that spent drilling fluids can contain high values of nickel and mercury (270 and 8.77 mg kg^-1_, respectively) and can exceed the maximum permissible limits recommended by the EC regulations for safety of soils (75 mg kg^-1 for nickel and 1.5 mg kg^-1 for mercury). The heavy metal concentrations in the studied drill cuttings did not exceed the maximum permissible limits recommended by the EC regulation. Drilling wastes contain macroelements (e.g., calcium, magnesium, and potassium) as well as trace elements (e.g., copper, iron, zinc, and manganese) that are essential for the plant growth. It was stated that water extracts of drilling fluids and drill cuttings, according to anions presence, had not any specific constituents of concern based on FAO irrigation guidelines, the USEPA WQC, and toxicity values. X-ray diffraction analysis was used to understand the structure and texture of waste drilling fluid solids and drill cuttings. Analysis of the mineralogical character of drilling fluid solids revealed that they contained calcite, quartz, muscovite, sylvite, barite, dolomite, and orthoclase. Drill cuttings contained calcite quartz, muscovite, barite, dolomite, and barium chloride.

Distribution and phytotoxicity of soil labile aluminum fractions and aluminum species in soil water extracts and their effects on tall fescue

Soil acidification can alter the biogeochemistry of ecosystems and adversely affect biota; however, there are still many debates about the toxicity of aluminum (Al) fractions and Al species in soil:water extracts to plants. In this study, five crude soils with different pH values (4.92-8.51) were collected, seeded with tall fescue and grown in rhizosphere boxes for 120 days. Then, soil properties, labile Al fractions and Al species in soil:water extracts were determined, and their toxicities to plants were analyzed. Our study showed that a stable exchangeable Al fraction (ExAl) pool exists and is supplied by other labile Al fractions. Dissolution of Al from adsorbed hydroxyl-Al fraction (HyAl) and organic-Al fraction (OrAl) may play important roles in soil Al toxicity, as HyAl and OrAl account for major parts of soil labile Al. Additionally, Al³⁺ and mononuclear hydroxyl-Al species in soil:water extracts have few effects to plants. Nevertheless, high negative correlations were found between Al-F^- complexes and tall fescue biomass, indicating their toxicity in the natural soil environment. Thus, in many cases, Al³⁺ toxicity should not be emphasized because of its lower activity in soil water extracts. Moreover, toxicities of AlF₃(aq) and AlF₄^- to plants should be emphasized, because they have been confirmed in soil water extracts in this study.

A paper platform for colorimetric determination of aluminum hydrochloride in antiperspirant samples

A simple, fast, low-cost, portable, and eco-friendly method using a spot test on a paper platform, together with diffuse reflectance spectroscopy, was developed and validated for the quantification of aluminum hydrochloride, a potential neurotoxic agent, in antiperspirant samples. The determination of aluminum hydrochloride was performed at a wavelength of 615 nm, by measuring consumption of the purple colorimetric reagent Alizarin S, due to reaction with aluminum. The linear range was from 10.0 to 125.0 mg L^-1 and could be described by the equation: A_R = 0.4479 - 0.002543 C_Al (R = 0.999). The limits of detection (LOD) and quantification (LOQ) were 3.06 and 10.2 mg L^-1, respectively. The method was specific, accurate, and repeatable, with relative standard deviation (RSD) <5.0%. The recovery was between 92.2 and 103.4%. The method was successfully used for the determination of aluminum hydrochloride in commercial antiperspirant samples, revealing concentrations below the maximum permitted by current legislation.

Utilization of calcium-based and aluminum-based materials for the treatment of stabilized landfill leachate: a comparative study

This study explored the efficiencies and mechanisms of refractory organic matters removal in the stabilized landfill leachate by adding different reagents. Calcium-based and aluminum-based materials were added into the leachate as comparing experiments. XRD, FTIR, and EEM were adopted to analyze the solid products and leachate. As a result, the in situ synthesized CaAl-LDHs were more beneficial for refractory organic matters removal, especially for benzodiazepines. When CaAl-LDHs were formed, the removal efficiencies of COD, UV254, and TOC were best and achieved 58.48, 81.22, and 71.30%, respectively. For fluorescent substances, humic acid-like and fulvic acid-like compounds were efficiently removed by CaAl-LDHs. In particular, CaAl-LDHs had selective removal effects on fulvic acid-like compounds, which were characteristic of small molecular weight and major carboxyl groups.

A note on unusual Si/Al ratios in PM10 and PM2.5 road dust at several locations in India

The Si/Al ratios in road dust (PM₁₀ and/or PM_2.5) at several locations in India were examined and found to range between 1.6 and 84.9. The potential factors for this wide range of unusual Si/Al ratios in road dust are not known at this time. In addition to re-assessing data quality, the observations suggest the need to carefully quantify anthropogenic inputs of these elements to road dust. The findings of this study also contradict popular assumptions about minimal enrichment of crustal elements by anthropogenic sources and highlight the need to re-visit dust mass estimation using Si and Al as a surrogate. Further, characterization of Si/Al ratio in road dust at locations in India and the influence of local geology/geochemistry on it are especially important, if this ratio is to be used either for dust estimation or as an input to ambient aerosol mass source apportionment models.

Investigation of discharged aerosol nanoparticles during chemical precipitation and spray pyrolysis for developing safety measures in the nano research laboratory

Nowadays, the demands for the nanoparticles are increasing due to their tremendous applications in various fields. As a consequence, the discharge of nanoparticles into the atmosphere and environment is also increasing, posing a health threat and environmental damage in terms of pollution. Thus, an extensive research is essential to evaluate the discharge of these nanoparticles into the environment. Keeping this in mind, the present investigation aimed to analyze the discharge of aerosol nanoparticles that are synthesized in the laboratory via chemical precipitation and spray pyrolysis methods. The results indicated that the chemical precipitation method discharges a higher concentration of nanoparticles in the work site when compared to the spray pyrolysis method. The aerosol concentration also varied with the different steps involved during the synthesis of nanoparticles. The average particle's concentration in air for chemical precipitation and spray pyrolysis methods was around 1,037,476 and 883,421particles/cm³. In addition, the average total discharge of nanoparticles in the entire laboratory was also examined. A significant variation in the concentration of nanoparticles was noticed, during the processing of materials and the concentration of particles (14-723nm) exceeding the daily allowed concentration to about 70-170 times was observed over a period of 6 months. Thus, the results of the present study will be very useful in developing safety measures and would help in organizing the rules for people working in nanotechnology laboratories to minimize the hazardous effects.

Sequential electrodialytic recovery of phosphorus from low-temperature gasification ashes of chemically precipitated sewage sludge

Phosphorus recycling from secondary materials like sewage sludge ashes offers an alternative to mining of phosphates from primary resources and a mean to counteract the current phosphorous rock depletion concern. A separation of P from the bulk ash is normally required, due to its low plant availability and the presence of heavy metals. Previously, more than 80% of P was recovered from incineration sewage sludge ashes using a two-compartment electrodialytic cell. In contrast, the recovery was below 30% for ashes from low-temperature gasification using the same setup. The low recovery was due to a high presence of Al- and Fe(III)-P bindings. In the present study, an electrodialytic process combining sequentially a pair of two-compartment cells allowed a recovery of up to 70% of phosphorus from these ashes. The use of a second cell, where the ash was suspended in an alkaline solution, allowed the P solubilisation from aluminium and ferric phosphates. In addition, P was separated from most metals as they became insoluble under the prevailing chemical environment. The obtained ratio of Al, Fe, Mg and most heavy metals to P was comparable to wet process phosphoric acid. Therefore, this sequential process was found to be suitable to recycle P and potentially use it in the production of common fertilizers like diammonium phosphate.

Performance assessment of MCM-48 ceramic composite membrane by separation of AlCl3 from aqueous solution

Three dimensional ordered mesoporous MCM-48 membrane was fabricated on a circular shaped ceramic support by in-situ hydrothermal method. The synthesized MCM-48 powder and MCM-48 ceramic composite membrane were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA) and field emission scanning electron microscopy (FESEM). The porosity and pore size of the composite membrane are reduced considerably by the deposition of MCM-48 on the support. The formation of MCM-48 is verified by the XRD analysis. Three stepwise mechanisms for surfactant removal are observed by TGA analysis. FESEM images clearly signify the deposition of MCM-48 on the ceramic support. The pure water flux of the support and MCM-48 composite membrane is found to be 3.63×10^-6 and 4.18×10^-8m³/m²skPa, respectively. The above prepared MCM-48 ceramic composite membrane is employed for the removal of AlCl₃ from aqueous solution and the highest rejection of 81% is obtained at an applied pressure of 276kPa with salt concentration of 250ppm.

Effects of Aluminum Exposure on the Bone Stimulatory Growth Factors in Rats

Aluminum (Al) is considered to be a potentially toxic metal and inhibits bone formation. Transforming growth factor β1 (TGF-β1) and bone morphogenetic protein 2 (BMP-2) play an important role in regulating the bone formation. Therefore, this study aimed to investigate the effects of Al on the TGF-β1 and BMP-2 in rats. In this study, Wistar rats were randomly divided into Al-treated group and control group. The Al-treated rats were provided with drinking water containing 100 mg/L AlCl3, and the control rats were given distilled water for 30, 60, and 90 days, respectively. Ten rats were sacrificed in each group every 30 days. The Al-treated rats showed lower body weight and higher serum and bone levels of Al compared with the control rats. The expression levels of TGF-β1 and BMP-2 were also significantly decreased in the Al-treated rats. Serum levels of bone gamma-carboxyglutamic acid protein (BGP), carboxy-terminal propeptide of type I procollagen (PICP), and bone alkaline phosphatase (B-ALP) were markedly lower in the Al-treated groups than in the control group. These results indicate that Al inhibits the expression of TGF-β1 and BMP-2 in bone, which inhibits the activity of osteoblasts and reduces the synthesis of BGP, B-ALP, and type I collagen, thereby inhibiting bone formation.

Immobilization of trace elements in municipal solid waste incinerator (MSWI) fly ash by producing calcium sulphoaluminate cement after carbonation and washing

The possibility of producing calcium sulphoaluminate cement (CSA) by adding municipal solid waste incinerator (MSWI) fly ash to raw meal was investigated. After subjecting MSWI fly ash to accelerated carbonation and washing with water (ACW), various amounts (i.e., 5, 10 and 15 wt%) of the treated ash were added to raw meal composed of a mixture of bauxite, limestone and gypsum. The mixtures were sintered in a laboratory-scale muffle furnace at temperatures of 1250°, 1300°, 1325° and 1350 °C for various durations. The influence of different quantities of MSWI fly ash on the mineralogy, major phase composition and strength development of the resulting clinker was studied, as was the effect of ash treatments on leaching and volatilization of trace elements. The ACW treatment reduced the volatilization ratio of trace elements during the clinkerization process. Volatilization ratios for lead, cadmium and zinc were 21.5%, 33.6% and 16.3%, respectively, from the ACW fly ash treatment, compared with ratios of 97.5%, 93.1% and 85.2% from untreated fly ash. The volatilization ratios of trace elements were ordered as follows: untreated fly ash > carbonated fly ash > carbonated and water-washed fly ash. The ACW process also reduced the chloride content in the MSWI fly ash by 90 wt% and prevented high concentrations of trace elements in the effluents.

Impact of aluminum chloride on process performance and microbial community structure of granular sludge in an upflow anaerobic sludge blanket reactor for natural rubber processing wastewater treatment

In this study, granular sludge formation was carried out using an aluminum chloride supplement in an upflow anaerobic sludge blanket (UASB) reactor treating natural rubber processing wastewater. Results show that during the first 75 days after the start-up of the UASB reactor with an organic loading rate (OLR) of 2.65 kg-COD·m(-3)·day(-1), it performed stably with a removal of 90% of the total chemical oxygen demand (COD) and sludge still remained in small dispersed flocs. However, after aluminum chloride was added at a concentration of 300 mg·L(-1) and the OLR range was increased up to 5.32 kg-COD·m(-3)·day(-1), the total COD removal efficiency rose to 96.5 ± 2.6%, with a methane recovery rate of 84.9 ± 13.4%, and the flocs began to form granules. Massively parallel 16S rRNA gene sequencing of the sludge retained in the UASB reactor showed that total sequence reads of Methanosaeta sp. and Methanosarcina sp., reported to be the key organisms for granulation, increased after 311 days of operation. This indicates that the microbial community structure of the retained sludge in the UASB reactor at the end of the experiment gave a good account of itself in not only COD removal, but also granule formation.

Mineral phases and metals in baghouse dust from secondary aluminum production

Baghouse dust (BHD) is a solid waste generated by air pollution control systems during secondary aluminum processing (SAP). Management and disposal of BHD can be challenging in the U.S. and elsewhere. In this study, the mineral phases, metal content and metal leachability of 78 BHD samples collected from 13 different SAP facilities across the U.S. were investigated. The XRD semi-quantitative analysis of BHD samples suggests the presence of metallic aluminum, aluminum oxide, aluminum nitride and its oxides, spinel, elpasolite as well as diaspora. BHD also contains halite, sylvite and fluorite, which are used as fluxes in SAP activities. Total aluminum (Al) in the BHD samples averaged 18% by weight. Elevated concentrations of trace metals (>100 μg L(-1) As; >1000 μg L(-1) Cu, Mn, Se, Pb, Mn and Zn) were also detected in the leachate. The U.S. toxicity characteristic leaching procedure (TCLP) results showed that some samples leached above the toxicity limit for Cd, Pb and Se. Exceeding the TCLP limits in all sample is independent of facilities generating the BHD. From the metal content perspective only, it appears that BHD has a higher potential to exhibit toxicity characteristics than salt cake (the largest waste stream generated by SAP facilities).

The environmental geochemistry of trace elements and naturally radionuclides in a coal gangue brick-making plant

An investigation focused on the transformation and distribution behaviors of trace elements and natural radionuclides around a coal gangue brick plant was conducted. Simultaneous sampling of coal gangue, brick, fly ash and flue gas were implemented. Soil, soybean and earthworm samples around the brick plant were also collected for comprehensive ecological assessment. During the firing process, trace elements were released and redistributed in the brick, fly ash and the flue gas. Elements can be divided into two groups according to their releasing characteristics, high volatile elements (release ratio higher than 30%) are represented by Cd, Cu, Hg, Pb, Se and Sn, which emitted mainly in flue gas that would travel and deposit at the northeast and southwest direction around the brick plant. Cadmium, Ni and Pb are bio-accumulated in the soybean grown on the study area, which indicates potential health impacts in case of human consumption. The high activity of natural radionuclides in the atmosphere around the plant as well as in the made-up bricks will increase the health risk of respiratory system.

Predicting failure: acoustic emission of berlinite under compression

Acoustic emission has been measured and statistical characteristics analyzed during the stress-induced collapse of porous berlinite, AlPO4, containing up to 50 vol% porosity. Stress collapse occurs in a series of individual events (avalanches), and each avalanche leads to a jerk in sample compression with corresponding acoustic emission (AE) signals. The distribution of AE avalanche energies can be approximately described by a power law p(E)dE = E(-ε)dE (ε ~ 1.8) over a large stress interval. We observed several collapse mechanisms whereby less porous minerals show the superposition of independent jerks, which were not related to the major collapse at the failure stress. In highly porous berlinite (40% and 50%) an increase of energy emission occurred near the failure point. In contrast, the less porous samples did not show such an increase in energy emission. Instead, in the near vicinity of the main failure point they showed a reduction in the energy exponent to ~ 1.4, which is consistent with the value reported for compressed porous systems displaying critical behavior. This suggests that a critical avalanche regime with a lack of precursor events occurs. In this case, all preceding large events were 'false alarms' and unrelated to the main failure event. Our results identify a method to use pico-seismicity detection of foreshocks to warn of mine collapse before the main failure (the collapse) occurs, which can be applied to highly porous materials only.

Inclusions in topaz from miarolitic pegmatites of the Volodarsk-Volynski Massif (Ukraine)--a Raman spectroscopic study

The differently coloured (colourless, brown-pinkish and blue-pinkish) crystals of topaz from granitic pegmatites of Volodarsk-Volynsky Massif (VVM) have been investigated by scanning electron microscopy (SEM) and Raman microspectroscopy (RS) methods. Topaz (287, 522, 855, 929 cm(-1)), goethite (390 cm(-1)), pyrite (377-379 cm(-1)), marcasite (397 and 331 cm(-1)) and monazite (460 and 970-1070 cm(-1)) were identified as mineral inclusions in analysed crystals. On the basis of RS spectra some of this inclusions contain also organic matter, represented by carbonaceous matter (D-band at ca. 1320-1340 cm(-1) and G-band at ca. 1590-1600 cm(-1)) and liquid simple hydrocarbons consisting of aliphatic and aromatic groups (1240, 1325 and 1420 cm(-1)). Other solid phases found the host topaz, i.e. quartz, orthoclase, very rare minerals (micas) as lepidolite, zinnwaldite and also beryl and rutile, were identified with SEM-EDS analyses. All these mineral inclusions have been formed by post-magmatic, fluid-induced processes, extended from pegmatite to hydrothermal stages of magma crystallization.

Death by caffeine: presumptive malicious poisoning of a dog by incorporation in ground meat

BACKGROUND

A 4-year-old, 37 kg, male German shepherd developed hyperthermia, tachycardia, and agitation following consumption of ground meat found in the backyard of its owner. When presented to a veterinary clinic, plasma ethylene glycol (EG) testing was positive, and the dog was given ethanol and lactated Ringer's solution intravenously. Approximately 11 h postexposure the dog died.

DISCUSSION

Among tissues submitted for toxicological analysis, urine was negative for EG, ground meat was negative for certain drugs of abuse, and gastric contents were negative for zinc/aluminum phosphide and metaldehyde. Analysis of gastric contents by gas chromatography-mass spectrometry confirmed the presence of caffeine. Caffeine concentration in the ground meat was estimated at 1 %. Caffeine is a methylxanthine alkaloid with a reported canine oral median lethal dose (MLD(50)) of 140 mg/kg (range 120-200 mg/kg). A commercially available 200-mg tablet formulation of caffeine was considered to be a possible source but this was not confirmed. By conservative estimates, the dog would need to ingest approximately 500-550 g of the meat to reach the MLD(50). Acute intoxication affects the cardiovascular, pulmonary, neurologic, gastrointestinal, and metabolic systems. Although no tablet remnants were observed in the bait, tablets could have been crushed and/or dissolved. Other potential caffeine sources include guarana, brewed and concentrated coffee, and caffeine-containing beverages. Based on the history, clinical signs, and the detection of caffeine in the gastric contents and meat, a presumptive diagnosis of malicious caffeine poisoning was made. A suggested treatment regimen for caffeine intoxication in dogs is described. While few cases of accidental ingestion of caffeine by dogs have been described, the intentional use of a concentrated caffeine source to cause mortality in a dog has not been previously reported.

What do results of common sequential fractionation and single-step extractions tell us about P binding with Fe and Al compounds in non-calcareous sediments?

Correct identification of P forms together with their main Fe and Al binding partners in non-calcareous sediments is of crucial importance for evaluation of P cycling in water bodies. In this paper, we assess extraction methods frequently used for this purpose, i.e., a sequential five-step fractionation (water, bicarbonate buffered dithionite solution (BD), NaOH, HCl, nitric-perchloric acid), ascorbate extraction (pH ~7.5), and oxalate extraction (pH ~3), directly on a range of laboratory prepared Fe and Al minerals enriched with adsorbed P. Extraction selectivity and efficiency for particular P, Fe and Al forms were also verified by specific combinations of these extraction methods applied on freshwater sediment samples. In the sequential fractionation, BD was highly effective in dissolving both amorphous and crystalline Fe (hydr)oxides and the associated P, while neither FeS nor Al (hydr)oxides were dissolved. The following NaOH extraction effectively dissolved both amorphous and crystalline Al (hydr)oxides. The high solubilizing power of BD and NaOH to dissolve crystalline Fe and Al oxides that have only a small P-sorption ability prevents the use of resulting Fe/P and Al/P ratios as simple predictors of total P sorption capacity of sediments and soils. Ascorbate non-selectively extracted small proportions of FeS and amorphous Fe and Al (hydr)oxides, but significant amounts of adsorbed P, which hinders its use for the characterization of P forms in non-calcareous sediments. Similar nonselective characteristics were found for oxalate extractions. As oxalate extracts most of the adsorbed phosphate, it is not possible to use it unambiguously to determine specific Fe/P and Al/P ratios of active complexes. However, this method is convenient (and more selective than NaOH step in the sequential fractionation) for the determination of amorphous Al (hydr)oxides.

Concentration of cadmium, nickel and aluminium in female breast cancer

AIMS

The aim of this study was to investigate the cadmium (Cd), nickel (Ni) and aluminium (Al) concentrations in female breast cancer and normal tissue.

MATERIALS AND METHODS

The concentration of metals in 16 non-cancerous breast tissues and 67 breast cancer samples was measured by flame atomic absorption spectrometry.

RESULTS

In the case of normal breast tissue the concentrations were 0.61 ± 0.24 μg Cd/g dry tissue, 1.84 ± 0.67 μg Ni/g dry tissue, and 3.63 ± 1.00 μg Al/g dry tissue, whereas in breast cancer concentrations of metals were 0.76 ± 0.38 μg/g dry tissue, 2.26 ± 0.79 μg/g dry tissue, and 4.40 ± 1.82 μg/g dry tissue, respectively. The concentration of Cd and Al in normal breast tissue was significantly lower than in breast cancer. In the case of Ni concentration, we did not observe statistically significant differences between normal and cancerous tissue. There were no significant differences in concentration of studied metals, in breast cancer, in the context of age, menopausal status, and cancer histological grading.

CONCLUSION

The data obtained show higher concentration of cadmium and aluminium and support a possible relationship between those metals and breast cancer.

Astrobiological considerations for the selection of the geological filters on the ExoMars PanCam instrument

The Panoramic Camera (PanCam) instrument will provide visible-near IR multispectral imaging of the ExoMars rover's surroundings to identify regions of interest within the nearby terrain. This multispectral capability is dependant upon the 12 preselected "geological" filters that are integrated into two wide-angle cameras. First devised by the Imager for Mars Pathfinder team to detect iron oxides, this baseline filter set has remained largely unchanged for subsequent missions (Mars Exploration Rovers, Beagle 2, Phoenix) despite the advancing knowledge of the mineralogical diversity on Mars. Therefore, the geological filters for the ExoMars PanCam will be redesigned to accommodate the astrobiology focus of ExoMars, where hydrated mineral terrains (evidence of past liquid water) will be priority targets. Here, we conduct an initial investigation into new filter wavelengths for the ExoMars PanCam and present results from tests performed on Mars analog rocks. Two new filter sets were devised: one with filters spaced every 50 nm ("F1-12") and another that utilizes a novel filter selection method based upon hydrated mineral reflectance spectra ("F2-12"). These new filter sets, along with the Beagle 2 filter set (currently the baseline for the ExoMars PanCam), were tested on their ability to identify hydrated minerals and biosignatures present in Mars analog rocks. The filter sets, with varying degrees of ability, detected the spectral features of minerals jarosite, opaline silica, alunite, nontronite, and siderite present in these rock samples. None of the filter sets, however, were able to detect fossilized biomat structures and small (<2 mm) mineralogical heterogeneities present in silica sinters. Both new filter sets outperformed the Beagle 2 filters, with F2-12 detecting the most spectral features produced by hydrated minerals and providing the best discrimination between samples. Future work involving more extensive testing on Mars analog samples that exhibit a wider range of mineralogies would be the next step in carefully evaluating the new filter sets.

Double-quantum homonuclear NMR correlation spectroscopy of quadrupolar nuclei subjected to magic-angle spinning and high magnetic field

We present a new application of the R2(2)(1) symmetry-based dipolar recoupling scheme, for exciting directly double-quantum (2Q) coherences between the central transition of homonuclear half-integer quadrupolar nuclei. With respect to previously published 2Q-recoupling methods (M. Eden, D. Zhou, J. Yu, Chem. Phys. Lett. 431 (2006) 397), the R2(2)(1) sequence is used without pi/2 bracketing pulses and with an original super-cycling. This leads to an improved efficiency (a factor of two for spin-5/2) and to a much higher robustness to radio-frequency field inhomogeneity and resonance offset. The 2Q-coherence excitation performances are demonstrated experimentally by (27)Al NMR experiments on the aluminophosphates berlinite, VPI5, AlPO(4)-14, and AlPO(4)-CJ3. The two-dimensional 2Q-1Q correlation experiments incorporating these recoupling sequences allow the observation of 2Q cross-peaks between central transitions, even at high magnetic field where the difference in offset between octahedral and tetrahedral (27)Al sites exceeds 10 kHz.

Proton NMR studies of the NaAlH4 structure

Advanced nuclear magnetic resonance (NMR) techniques were applied to study the local environments of hydrogen in NaAlH(4). Through a combined application of the magic echo (ME) and the magic Hahn echo (MHE) sequences the hetero- and homonuclear contributions to the dipolar second moment (M(2)) were determined separately. The obtained values are compared with the second moments calculated by the van Vleck formulae, using structural data determined by neutron scattering on NaAlD(4). This comparison indicates structural differences between NaAlH(4) and NaAlD(4). A model is suggested for the orientation of the [AlH(4)](-) tetrahedra in NaAlH(4), for which the calculated second moments are in good agreement with the experimentally observed values.

[Effects of temperature and pH on the distribution of aluminum species in drinking water]

The effects of aluminum on water distribution system and human health are mainly attributable to their presence in drinking water. Laboratory experiments were performed to investigate the influence of temperature and pH on the distribution of aluminum species applying alum synthetic water. Aluminum species studied in the experiments included monomeric aluminum, soluble aluminum, suspended aluminum, and polymeric aluminum, which were determined by fluorescence spectrophotometry method. Results indicated that suspended aluminum was the major species at pH 6.5, occupied about 62.2% in the total aluminum mass concentration. While at pH above 7.0, monomeric aluminum was the major species; and varied little as reaction time increased. Polymeric aluminum mass concentration was low at studied water quality condition and also varied little as reaction time increased. The influence of temperature on aluminum species distribution was similar to solution pH; and both could be explained by pOH. Aluminum species in drinking water could be controlled by adjusting the pOH value, which provided theoretical guidance for the operation of the water distribution system and aluminum toxicity control.

Efficient preconcentration and determination of traces of aluminum ion using silica-bonded glycerol sorbent

A solid-phase extraction system was proposed for the determination of aluminum after preconcentration with glycerol-bonded silica gel. The method is rapid and efficient for the enrichment of aluminum ions at trace levels. Optimal sorption conditions were found for sorption and desorption of aluminum ions. The effects of diverse ions on the sorption and recovery of aluminum have been studied and it was shown that the selectivity of the sorption process was very good. A very satisfactory preconcentration factor of 500 was achieved by this method. The lowest concentration of aluminum ions for quantitative recovery was 2ngml(-1). The capacity of sorbent was 400microg per gram of sorbent. The method showed good reproducibility (R.S.D.=2.2% for n=7) and was applied to the determination of aluminum in mineral water, hair and green tea samples.

[Studies on IR spectroscopy and quantum chemical calculation of chloroaluminate ionic liquids acidity]

The acidity of chloroaluminate ionic liquids and the interaction mechanism of Lewis acid site Al2Cl7(-) of chloroaluminate ionic liquid and pyridine were experimentally investigated by IR characterization by using pyridine as molecular probe and increasing pyridine adsorption, and theoretically confirmed by quantum chemical calculations at density functional theory (DFT) and ab initio levels. It was found that the anions, Al2Cl7(-) and AlCl4(-), which could withdraw lone pair electrons of pyridine, were characteristic of Lewis acid. Therefore, they displayed pyridine coordinated to Lewis acidic site using pyridine as probe. The acidity of Al2Cl7(-) was found stronger than that of AlCl4(-) by analyzing IR absorption frequency, bond length and charge distribution. The mechanism of forming and evolvement of the Lewis acid site Al2Cl7(-) of chloroaluminate ionic liquid was proposed. When the amount of pyridine is small, only the adsorption state of Py-Al2Cl7(-) exists. The highly Lewis acidic adsorption state of Py-Al2Cl7(-) complex was converted into Py-AlCl4(-) complex and Py-AlCl3 complex with increasing pyridine contents, leading to the changes in IR absorption spectra.

[Al species distribution survey in portable water distribution system in a north city of China]

The residual Al concentration and species distribution of a north Chinese city was surveyed using fluorimetry. Results showed that the highest total Al concentration was 0.078 mg x L(-1) and the mean concentration was 0.038 mg x L(-1), lower than the latest portable water standard of 0.2 mg x L(-1). Inorganic mono-aluminum and inorganic poly-aluminum, the main toxicity-leading species, were also the major existence species with the mean concentration 0.011 mg x L(-1) and 0.013 mg x L(-1) respectively. While organic combined aluminum concentration was quite low. Correlation analysis results showed that the Al concentration and species distribution in a certain pipe line was connected with the water quality. When the distribution system contained more salts and less soluble organic matter, the Al concentration would be controlled in a low level, which was important to guide the local operation.

Exposure to chemical agents in aluminium potrooms

OBJECTIVES

To assess the effects of modernization of aluminium production on reducing the chemical health hazards in the working environment in aluminium potrooms (smelter). Modernization included the introduction ofa technique of point feeding of alumina and aluminium fluoride into the pots, semi-automatic equipment and computerized control.

METHODS

Periodical environmental measurements of chemical substances, dusts containing alumina and fluorides, and gases, i.e., carbon monoxide, carbon dioxide, sulphur dioxide, hydrogen fluoride, nitrogen dioxide, and difluorosulphide, were performed at the same workplaces before (1986-1988) and sixteen years later, after modernization (2004). The measured values were compared with the recommended occupational safety and health standards.

RESULTS

The concentrations of total dust (alumina and fluorides) and gases, i.e., carbon monoxide, carbon dioxide, sulphur dioxide, hydrogen fluoride and phenol, were above the recommended standards in 76.6% (95/124) of the samples before modernization and in only 23.8% (57/240) of the samples tested after modernization. Before modernization in almost all jobs the workers were simultaneously exposed to higher concentrations of all chemical agents present in the working environment. After modernization high concentrations of hydrogen fluoride were the primary pollutant in this plant (GM = 4.5451 ppm), while the presence of other gases was significantly reduced. Dusts containing alumina and fluorides and hydrogen fluoride gas were still present in considerable concentrations in the working environments of jobs such as changing and covering of anodes.

CONCLUSION

The modernization of the aluminium smelter plant reduced the concentrations of the most harmful substances in the working environment and reduced the number of jobs where workers were simultaneously exposed to a variety of health hazards.

Effects of EDTA on the hydration mechanism of mineral trioxide aggregate

Ethylenediaminetetraacetic acid (EDTA) is commonly used during the preparation of obstructed root canals that face a high risk of root perforation. Such perforations may be repaired with mineral trioxide aggregate (MTA). Due to EDTA's ability to chelate calcium ions, we hypothesized that EDTA may disrupt the hydration of MTA. Using scanning electron microscopy and energy-dispersive x-ray spectroscopy, we found that MTA specimens stored in an EDTA solution had no crystalline structure and a Ca/Si molar ratio considerably lower than those obtained for specimens stored in distilled water and normal saline. Poor cell adhesion in EDTA-treated MTA was also noted. X-ray diffraction indicated that the peak corresponding to portlandite, which is normally present in hydrated MTA, was not shown in the EDTA group. The microhardness of EDTA-treated specimens was also significantly reduced (p < 0.0001). These findings suggest that EDTA interferes with the hydration of MTA, resulting in decreased hardness and poor biocompatibility.

Interactive effects of soil acidity and fluoride on soil solution aluminium chemistry and barley (Hordeum vulgare L.) root growth

A greenhouse study was conducted to determine if concentrations of fluoride (F), which would be added to acid soils via P fertilisers, were detrimental to barley root growth. Increasing rates of F additions to soil significantly increased the soil solution concentrations of aluminium (Al) and F irrespective of the initial adjusted soil pH, which ranged from 4.25 to 5.48. High rates of F addition severely restricted root growth; the effect was more pronounced in the strongly acidic soil. Speciation calculations demonstrated that increasing rates of F additions substantially increased the concentrations of Al-F complexes in the soil. Stepwise regression analysis showed that it was the combination of the activities of AlF2(1+) and AlF(2+) complexes that primarily controlled barley root growth. The results suggested that continuous input of F to soils, and increased soil acidification, may become an F risk issue in the future.

Synthesis of nanocrystalline (Co, Ni)Al2O4 spinel powder by mechanical milling of quasicrystalline materials

In the present study, attempts have been made to synthesize the nano-crystalline (Co, Ni)Al2O4 spinel powders by ball milling and subsequent annealing. An alloy of Al70Co15Ni15, exhibiting the formation of a complex intermetallic compound known as decagonal quasicrystal is selected as the starting material for mechanical milling. It is interesting to note that this alloy is close to the stoichiometry of aluminum and transition metal atoms required to form the aluminate spinel. The milling was carried out in an attritor mill at 400 rpm for 40 hours with ball to powder ratio of 20 : 1 in hexane medium. Subsequent to this annealing was performed in an air ambience for 10, 20, and 40 h at 600 degrees C in side the furnace in order to oxidize the decagonal phase and finally to form the spinel structure. The X-ray diffraction (XRD) and transmission electron microscopy (TEM) confirmed the formation of nano-sized decagonal phase after milling and then (Co, Ni)Al2O4 spinel type phase after annealing. The XRD studies reveal the lattice parameter to be 8.075 angstroms and the lattice strain as 0.6%. The XRD and TEM explorations of spinel phase indicate the average grain size to be approximately 40 nm.

Arsenic removal by electrocoagulation using combined Al-Fe electrode system and characterization of products

Combination of electrodes, such as aluminum and iron in a single electrochemical cell provide an alternative method for removal of arsenic from water by electrocoagulation. The removal process has been studied with a wide range of arsenic concentration (1-1000 ppm) at different pH (4-10). Analysis of the electrochemically generated by-products by XRD, XPS, SEM/EDAX, FT-IR, and Mössbauer Spectroscopy revealed the expected crystalline iron oxides (magnetite (Fe3O4), lepidocrocite (FeO(OH)), iron oxide (FeO)) and aluminum oxides (bayerite (Al(OH)3), diaspore (AlO(OH)), mansfieldite (AlAsO(4).2(H2O)), as well as some interaction between the two phases. The amorphous or very fine particular phase was also found in the floc. The substitution of Fe3+ ions by Al3+ ions in the solid surface has been observed, indicating an alternative removal mechanism of arsenic in these metal hydroxides and oxyhydroxides by providing larger surface area for arsenic adsorption via retarding the crystalline formation of iron oxides.

Three-dimensional through-bond homonuclear-heteronuclear correlation experiments for quadrupolar nuclei in solid-state NMR applied to (27)Al-O-(31)P-O-(27)Al networks

We present here the first 3D homonuclear/heteronuclear correlation experiment applied to quadrupolar nuclei and making use of the sole scalar J-coupling. This experiment, based on the 2D-Homonuclear-Heteronuclear Single Quantum Correlation (H-HSQC) experiment, uses a relayed transfer from the (27)Al central transition to neighbouring (31)P spins and to the central transition of a second (27)Al. It confirms the correlation map characterizing the two (27)Al and the (31)P NMR signatures of (27)Al-O-(31)P-O-(27)Al chemically bonded molecular motifs.

HMQC and refocused-INEPT experiments involving half-integer quadrupolar nuclei in solids

Hetero-nuclear coherence transfers in HMQC and refocused-INEPT experiments involving half-integer quadrupolar nuclei in solids are analyzed. 1D and 2D schemes are considered under MAS for the general case of multi-spin systems SI(n) (n4), where S is an observed nucleus. These results are also discussed in the context of high-resolution schemes featuring MQMAS or STMAS. The theoretical predictions are verified experimentally in a series of 1D and 2D experiments performed at 9.4 and 18.8T.

Coagulation and electrocoagulation of wastes polluted with dyes

Dyes are common pollutants in a large variety of industrial wastewaters, and the treatment of these wastes by coagulation has been extensively studied in the literature. This work is focused on the comparison of the efficiencies of the chemical and the electrochemical coagulation processes with hydrolyzing aluminum salts, and it tries to determine the similarities or differences that exist between the two coagulation processes. To do this, Eriochrome Black T solutions were used as a model of dye-polluted wastewater, and experiments of both coagulation technologies were planned to meet the same operation conditions. The pH, the aluminum concentration, the type of electrolyte, and the mode of dosing of aluminum were found to influence the process. Moreover, the speciation of aluminum was found to be the key parameter to explain the results, in terms of the mechanisms previously proposed in the literature for dissolved organic matter coagulation.

Examination of the jarosite-alunite precipitate addition in the raw meal for the production of sulfoaluminate cement clinker

The aim of the present research work was to investigate the possibility of adding a jarosite-alunite chemical precipitate, a waste product of a new hydrometallurgical process developed to treat economically low-grade nickel oxides ores, in the raw meal for the production of sulfoaluminate cement clinker. For that reason, two samples of raw meals were prepared, one contained 20% gypsum, as a reference sample ((SAC)Ref) and another with 11.31% jarosite-alunite precipitate ((SAC)J/A). Both raw meals were sintered at 1300 degrees C. The results of chemical and mineralogical analyses as well as the microscopic examination showed that the use of the jarosite-alunite precipitate did not affect the mineralogical characteristics of the so produced sulfoaluminate cement clinker and there was confirmed the formation of the sulfoaluminate phase (C4A3S), the most typical phase of this cement type. Furthermore, both clinkers were tested by determining the grindability, setting time, compressive strength and expansibility. The hydration products were examined by XRD analysis at 2, 7, 28 and 90 days. The results of the physico-mechanical tests showed that the addition of jarosite-alunite precipitate did not negatively affect the quality of the produced cement.

Aluminium rhizotoxicity in maize grown in solutions with Al3+ or Al(OH)-4 as predominant solution Al species

The rhizotoxicity of aluminium at low-pH with Al(3+) and at high pH with Al(OH)-(4) as the main Al species was studied. Aluminium reduced root growth to similar levels at pH 8.0 and pH 4.3, although the mononuclear Al concentration at pH 8.0 was three times lower than at pH 4.3. Al contents of root apices were much higher at pH 8 than at pH 4.3. Callose was induced only marginally at pH 8 and the formation was confined to the epidermis, whereas it proceeded through the cortex with time at pH 4.3. Well-documented genotypical differences in callose formation and Al accumulation could not be found at pH 8. The largest fraction of the root-tip Al was recovered in the cell-wall fraction independent of the solution pH. A sequential extraction of isolated cell walls suggests that most of the cell-wall Al was precipitated Al(OH)(3) at pH 8.0. This can be explained by a drastic pH reduction in the root apoplastic sap to 6.2, whereas at bulk solution pH 4.3 it rose to 5.6. Al precipitation was also confirmed by the microscopic localization of Al. At pH 8, Al could mostly be found in the epidermis, but in the apoplast of the outer cortex at pH 4.3. It is proposed here that at pH 4.3, Al(3+) inhibits root growth through binding to sensitive binding sites in the apoplast of the epidermis and the outer cortex. At pH 8, Al(OH)(3) precipitation in the epidermis causes a mechanical barrier thus impairing the root-growth control of the epidermis.

Flow Injection Spectrophotometric Determination of Tetracycline in a Pharmaceutical Preparation by Complexation with Aluminium(III)

A rapid flow injection (FI) spectrophotometric procedure for tetracycline determination is described. It is based on the injection of a 100 microl sample solution containing tetracycline into merged streams of aluminium(III) chloride (0.01 mol 1(-1)) and Tris-buffer in the presence of KCl (0.06 mol l(-1)), pH 7.0, with the same optimum flow rate of 3.2 ml min(-1). A yellow Al(III)-tetracycline complex was monitored at 376 nm. The flow injection system and the experimental conditions were optimized by means of the univariate method. The procedure was applied to the determination of tetracycline in pharmaceutical preparations with a high sampling rate of at least 165 h(-1). A high precision with a relative standard deviation was obtained less than 0.72 and 0.30% of 5.0 and 10 microg ml(-1) (n=11), respectively. The detection limit (3sigma) and the quantification limit (10sigma) were 0.07 and 0.72 mg l(-1), respectively. There were no interference effects from traditional excipients in the dosage forms when the method was applied to pharmaceutical preparations. The matrix effect could be reduced by the standard addition method.

High field ENDOR as a characterization tool for functional sites in microporous materials

The determination of the details of the spatial and electronic structure of functional sites (centers) in any system, be it in materials chemistry or in biology, is the first step towards understanding their function. When such sites happen to be paramagnetic in any point of their activity cycle, the tool box offered by a variety of high resolution electron paramagnetic resonance (EPR) spectroscopic techniques becomes very attractive for their characterization. This tool box has been considerably expanded by the developments in high field (HF) EPR in general, and HF electron nuclear double resonance (ENDOR), in particular. These have led to numerous new applications in the fields of biology, physics, chemistry and materials sciences. This overview focuses specifically on recent applications of pulsed HF ENDOR spectroscopy to microporous materials, such as zeotype materials, presenting the new opportunities it offers. First, a brief description of the theoretical basis required for the analysis of the HF ENDOR spectrum is given, followed by a description of the pulsed techniques used to record spectra and assign the signals, along with a brief presentation of the required instrumentation. Next, specific applications are given, including transition metal ions and complexes exchanged into zeolite cages, transition metal substitution into frameworks of zeolites, aluminophosphate molecular sieves, and silicious mesoporous materials, the interaction of NO with Lewis sites in zeolite cages and trapped S. We end with a discussion of the advantages and the shortcomings of the method and conclude with a future outlook.

[Ecological toxicity of aluminum-based coagulant on representative corps in neutral environment]

By the terrestrial ecotoxicological methods of seed germination and root elongation, and with aluminum-based coagulant AlCl3 which was widely used in wastewater- and water treatment as an example, this work studied the toxicological effects of aluminum-based coagulants on representative crops, including radish Raphanus sativus, cabbage Brassica chinensis and wheat Triticum aestivum, over a range of exposure concentrations under the neutral condition (pH= 7.0), with contrast to an acid condition (pH= 4.00). The results indicated that there was a significantly positive correlation between the concentration of AlCl3 and the inhibitory rate of root elongation and seed germination either under pH 7.0 or 4.0 (P < 0.01). Cabbage and wheat was more susceptive to AlCl3 toxicity under acid than under neutral condition, while radish was in adverse. The minimum inhibitory concentration of AlCl3 (< 2.0 mg x L(-1)) was lower under neutral than under acid condition.