Stabilization of the Neutral [25]Hexaphyrin(1.0.1.0.1.0) Radical by Hetero-Bimetal-Coordination

Stabilization of hexaphyrin(1.0.1.0.1.0) (named "rosarin") in its 25π radical state is achieved using a hetero-bimetal-coordination strategy. The antiaromatic BF2 complex B-1 was first synthesized, and then rhodium ion was inserted into B-1 to produce the BF2/Rh(CO)2 mixed complex Rh-B-1 as a highly air-stable radical. The structures of B-1 and Rh-B-1 were determined by single-crystal X-ray diffractions, and the antiaromatic or radical character was identified by various spectroscopy evidence and theoretical calculations. Rh-B-1 exhibits excellent redox properties, enabling amphoteric aromatic-antiaromatic conversion to their 24/26π states. Compared to the 24/26π conjugation systems on the same skeleton, Rh-B-1 has the narrowest electrochemical and optical band gaps, with the longest absorption band at 1010 nm. The ring-current analysis reveals intense paratropic currents for B-1 and co-existing diatropic-paratropic currents for Rh-B-1. This hetero-bimetal-coordination system provides a novel platform for organic radical stabilization on porphyrinoids, showing the prospect of modulating ligand oxidation states through rational coordination design.

Crystalline 2π Aromatic Azadiboriridinylium: A BN Analogue of Cyclopropenylium Cation

N-Substitution of a thermally unstable diboratriazole 1 with a trimethylsilyl group affords a remarkably stable diboratriazole derivative 2. Ring contraction of 2 with an N-heterocyclic carbene accompanied by the release of N2 as well as 1,4-hydrogen shift affords a carbene-stabilized azadiboriridine 3. Abstraction of the H-B3mem hydride in 3 with methyl trifluoromethanesulfonate leads to the isolation of a hitherto unknown azadiboriridinylium 4, the first BN analogue of cyclopropenylium cation. X-ray diffraction analysis and computational studies confirmed the delocalization of π electrons over the B2 N three-membered ring, indicating the 2π aromatic feature. Compound 4 undergoes ring expansion reactions with azobenzene and pyridazine to furnish triazadiborolidinylium species 5 and 6, the latter of which possesses a cationic B2 N3 ring with a pronounced 6π aromatic property. Moreover, the reaction of 4 with a diazo compound produces a cationic B2 N3 C pentafulvene derivative 7.

Recent progress in identification of water disinfection byproducts and opportunities for future research

Numerous disinfection by-products (DBPs) are formed from reactions between disinfectants and organic/inorganic matter during water disinfection. More than seven hundred DBPs that have been identified in disinfected water, only a fraction of which are regulated by drinking water guidelines, including trihalomethanes, haloacetic acids, bromate, and chlorite. Toxicity assessments have demonstrated that the identified DBPs cannot fully explain the overall toxicity of disinfected water; therefore, the identification of unknown DBPs is an important prerequisite to obtain insights for understanding the adverse effects of drinking water disinfection. Herein, we review the progress in identification of unknown DBPs in the recent five years with classifications of halogenated or nonhalogenated, aliphatic or aromatic, followed by specific halogen groups. The concentration and toxicity data of newly identified DBPs are also included. According to the current advances and existing shortcomings, we envisioned future perspectives in this field.

Toxicity of exhaust emissions from high aromatic and non-aromatic diesel fuels using in vitro ALI exposure system

The differences in the traffic fuels have been shown to affect exhaust emissions and their toxicity. Especially, the aromatic content of diesel fuel is an important factor considering the emissions, notably particulate matter (PM) concentrations. The ultra-fine particles (UFP, particles with a diameter of <100 nm) are important components of engine emissions and connected to various health effects, such as pulmonary and systematic inflammation, and cardiovascular disorders. Studying the toxicity of the UFPs and how different fuel options can be used for mitigating the emissions and toxicity is crucial. In the present study, emissions from a heavy-duty diesel engine were used to assess the exhaust emission toxicity with a thermophoresis-based in vitro air-liquid interface (ALI) exposure system. The aim of the study was to evaluate the toxicity of engine exhaust and the potential effect of 20 % aromatic fossil diesel and 0 % aromatic renewable diesel fuel on emission toxicity. The results of the present study show that the aromatic content of the fuel increases emission toxicity, which was seen as an increase in genotoxicity, distinct inflammatory responses, and alterations in the cell cycle. The increase in genotoxicity was most likely due to the PM phase of the exhaust, as the exposures with high-efficiency particulate absorbing (HEPA)-filtered exhaust resulted in a negligible increase in genotoxicity. However, the solely gaseous exposures still elicited immunological responses. Overall, the present study shows that decreasing the aromatic content of the fuels could be a significant measure in mitigating traffic exhaust toxicity.

Meta-analyses of arsenic accumulation in Indica and Japonica rice grains

Arsenic (As) is a worldwide concern because of its toxic effects on crop yield and prevalence in the food chain. Rice is consumed by half of the world's population and is known to accumulate As. The present study reviews the available literatures on As accumulation in different subspecies of rice grains (indica, japonica and aromatic) and performs meta-analyses for grain size and texture; these data include 120 studies conducted over the last 15 years across different parts of the world. Aromatic rice varieties accumulate less As with its 95% confidence interval (CI) being 73.90 - 80.94 μg kg^-1 which is significantly lower than the As accumulation by either indica or japonica rice varieties with their overall 95% CI being 135.48 - 147.78 μg kg^-1 and 204.71 - 212.25 μg kg^-1, respectively. Japonica rice varieties accumulate higher As than indica rice grains and within each subspecies polished and/or shorter rice grains accumulated significantly lower As compared to larger and/or unpolished grains; 95% CIs for the polished indica and japonica rice varieties are seen to be 96.33 - 111.11 μg kg^-1 and 203.34 - 211.09 μg kg^-1, respectively, whereas the same for unpolished varieties are seen to be 215.99 - 238.18 μg kg^-1 and 215.27 - 248.63 μg kg^-1, respectively. This shows that rice-based As bioaccumulation in humans could be lowered by increased use of aromatic or polished indica rice varieties, followed by the cultivation of shorter polished grains of japonica rice. These findings will be important to inform policy on rice cultivation and dietary uptake of As for a large portion of the global population.

Computational and comparative investigation of hydrophobic profile of spike protein of SARS-CoV-2 and SARS-CoV

The hydrophobic force is one of the most dominant factors in protein folding. A protein becomes functional only when it achieves its three-dimensional structure and stability upon folding. For a better understanding of the hydrophobic effects and their function in protein folding, quantitative measurement of the hydrophobicity of amino acid side chains is crucial. Spike protein is the primary structural protein in SARS-CoV-2 and SARS-CoV. This study explores how protein sequences in SARS-CoV-2 and SARS-CoV spike proteins encode hydrophobic interactions. Computational tools/techniques have been utilized to investigate the protein sequences of the spike proteins of SARS-CoV-2 and SARS-CoV. Investigations provided an estimate of hydrophobic distribution and its relative strength, indicating a hydrophobic pattern. Analysis of the spike protein's hydrophobic profile may help identify and treat the virus-caused disease; additionally, it can give an insight into the transmissibility and pathogenicity of the virus.

Photophysics of nanographenes: from polycyclic aromatic hydrocarbons to graphene nanoribbons

Graphene quantum dots (GQDs) and nanoribbons (GNRs) are classes of nanographene molecules that exhibit highly tunable photophysical properties. There have been great strides in recent years to advance our understanding of nanographene photophysics and develop their use in light-harvesting systems, such as artificial photosynthesis. Here, we review the latest studies of GQDs and GNRs which have shed new light onto their photophysical underpinnings through computational and advanced spectroscopic techniques. We discuss how the size, symmetry, and shape of nanographenes influence their molecular orbital structures and, consequentially, their spectroscopic signatures. The scope of this review is to comprehensively lay out the general photophysics of nanographenes starting with benzene and building up to larger polycyclic aromatic hydrocarbons, GQDs, and GNRs. We also explore a collection of publications from recent years that build upon the current understanding of nanographene photophysics and their potential application in light-driven processes from display, lasing, and sensing technology to photocatalytic water splitting.

Floristic biodiversity, biogeographical significance, and importance of Morocco's Arganeraie Biosphere Reserve

The coastal and subcoastal areas of west-central Morocco (Safi to Draa River, the Souss Valley, and the southern part of the western High Atlas and northern and southern slopes of the western Anti-Atlas) are characterized by typical Infra-Mediterranean vegetation ranking them amongst the important of the remarkable borderlands of North Africa. The flora is determined by complex historical and environmental factors occurring since the Tertiary period. The originality of this sector is due to the presence of the argan tree (Argania spinosa (L.) Skeels), Moroccan gum (Acacia gummifera Willd), olive trees (Olea europaea L. subsp. maroccana (Greuter & Burdet) P. Vargas & al.), a thermophilic flora adapted to an arid climate with several endemic species. This flora constitutes the final barrier against the desert and is of environmental and socioeconomical interest. Leaves and fruits provide forage material, while wood is used for fuel. Argan fruits are collected for their oily constitutes and for nutritional, cosmetic, and medicinal properties. Additionally, many species of Argan ecosystems are used in medicine and cosmetics. Recognizing its ecological value and local economic importance, the Argan region was declared a UNESCO Biosphere Reserve in 1998. Despite their biogeographical, historical, and socioeconomic value, vegetation structures in west-central Morocco are vulnerable and threatened by human activities. They exhibit high levels of degradation due to increasing clearance, overgrazing, and overexploitation. The area requires high conservation priority and sustainable management strategies for key species and genetic diversity.

Application of the Target Lipid Model to Assess Toxicity of Heterocyclic Aromatic Compounds to Aquatic Organisms

Heterocyclic aromatic compounds can be found in crude oil and coal and often co-exist in environmental samples with their homocyclic aromatic counterparts. The target lipid model (TLM) is a modeling framework that relates aquatic toxicity to the octanol-water partition coefficient (K_OW ) that has been calibrated and validated for hydrocarbons. A systematic analysis of the applicability of the TLM to heterocyclic aromatic compounds has not been performed. The objective of the present study was to compile reliable toxicity data for heterocycles and determine whether observed toxicity could be successfully described by the TLM. Results indicated that the TLM could be applied to this compound class by adopting an empirically derived coefficient that accounts for partitioning between water and lipid. This coefficient was larger than previously reported for aromatic hydrocarbons, indicating that these heterocyclic compounds exhibit higher affinity to target lipid and toxicity. A mechanistic evaluation confirmed that the hydrogen bonding accepting moieties of the heteroatoms helped explain differences in partitioning behavior. Given the TLM chemical class coefficient reported in the present study, heterocyclic aromatics can now be explicitly incorporated in TLM-based risk assessments of petroleum substances, other products, or environmental media containing these compounds. Environ Toxicol Chem 2021;40:3000-3009. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Advances in engineering microbial biosynthesis of aromatic compounds and related compounds

Aromatic compounds have broad applications and have been the target of biosynthetic processes for several decades. New biomolecular engineering strategies have been applied to improve production of aromatic compounds in recent years, some of which are expected to set the stage for the next wave of innovations. Here, we will briefly complement existing reviews on microbial production of aromatic compounds by focusing on a few recent trends where considerable work has been performed in the last 5 years. The trends we highlight are pathway modularization and compartmentalization, microbial co-culturing, non-traditional host engineering, aromatic polymer feedstock utilization, engineered ring cleavage, aldehyde stabilization, and biosynthesis of non-standard amino acids. Throughout this review article, we will also touch on unmet opportunities that future research could address.

The adsorption of aromatic macromolecules on graphene with entropy-tailored behavior and its utilization in exfoliating graphite

Aromatic macromolecules tend to form a compact conformation after physically adsorbed on graphene and it brings about great entropy loss for physisorption, due to the strong interaction between aromatic macromolecules and graphene. However, previous researches have validated the availability of aromatic macromolecules to stabilize graphene based on physisorption. In order to clarify the underlying mechanism of this physisorption process on graphene, a series of aromatic polyamide copolymers are used as models in this research. Apart from their adsorbed conformations on graphene, the conformations of these copolymers as the free states in diluted solutions are taken into consideration. Although these copolymers present the fully extended conformation on graphene, their conformations in diluted solutions vary largely with the copolymer composition. It is verified that the copolymer with smaller conformational change could have the better stabilization effectiveness for graphene, rather than the one having stronger interaction with graphene. Therefore, the entropy-tailored behavior for the adsorption of aromatic macromolecules on graphene is put forward. Based on this mechanism, the chemical structure of aromatic polyamide is optimized and furthermore it is utilized to directly exfoliate natural graphite flakes. Eventually, high-quality graphene nanosheets with a large dimension and low defects are obtained. Moreover, its exfoliating effectiveness is superior to those of the commonly used exfoliating agents nowadays.

Hydrogen movements in the oxidative half-reaction of kynurenine 3-monooxygenase from Pseudomonas fluorescens reveal the mechanism of hydroxylation

Kynurenine 3-monoxygenase (KMO) catalyzes the conversion of l-kynurenine (L-Kyn) to 3-hydroxykynurenine (3-OHKyn) in the pathway for tryptophan catabolism. We have investigated the effects of pH and deuterium substitution on the oxidative half-reaction of KMO from P. fluorescens (PfKMO). The three phases observed during the oxidative half reaction are formation of the hydroperoxyflavin, hydroxylation and product release. The measured rate constants for these phases proved largely unchanging with pH, suggesting that the KMO active site is insulated from exchange with solvent during catalysis. A solvent inventory study indicated that a solvent isotope effect of 2-3 is observed for the hydroxylation phase and that two or more protons are in flight during this step. An inverse isotope effect of 0.84 ± 0.01 on the rate constant for the hydroxylation step with ring perdeutero-L-Kyn as a substrate indicates a shift from sp² to sp³ hybridization in the transition state leading to the formation of a non-aromatic intermediate. The pH dependence of transient state data collected for the substrate analog meta-nitrobenzoylalanine indicate that groups proximal to the hydroperoxyflavin are titrated in the range pH 5-8.5 and can be described by a pKa of 8.8. That higher pH values do not slow the rate of hydroxylation precludes that the pKa measured pertains to the proton of the hydroperoxflavin. Together, these observations indicate that the C4a-hydroperoxyflavin has a pKa ≫ 8.5, that a non-aromatic species is the immediate product of hydroxylation and that at least two solvent derived protons are in-flight during oxygen insertion to the substrate aromatic ring. A unifying mechanistic proposal for these observations is proposed.

Stability of the permafrost peatlands carbon pool under climate change and wildfires during the last 150 years in the northern Great Khingan Mountains, China

Peatlands store one-third of the total global soil carbon (C.) despite covering only 3-4% of the global land surface. Most peatlands are distributed in mid-high latitude regions and are even in permafrost regions, are sensitive to climate change and are disturbed by wildfire. Although several studies have focused on the impact of historical climate change and regional human activities on the C. accumulation process in these peatlands, the impact of these factors on the stability of the C. pool remains poorly understood. Here, based on the ²¹⁰Pb age-depth model, we investigated the historical variations of C. stability during the last 150 years for five typical peatlands in the northern Great Khingan Mountains (Northeast China), an area located in a permafrost region that is sensitive to climate change and to wildfires, which have clearly increased due to regional human activities. The results showed that low C. accumulation rates (CARs) and weakly C. stability in studied peatlands before 1900. While, the increasing anthropogenic wildfire frequency and the residual products (e.g. pyrogenic carbon) increased the CARs and C. stability in peatlands from 1900 to 1980. The mean July temperature is the most important climate factor for peatlands C. stability. After 1980, due to the low wildfire frequencies influenced by human policies, increasing temperatures and decreasing precipitation not only increased the CARs but also markedly increased the C. stability of the peatlands C. pool in the northern Great Khingan Mountains, especially after 2000.

Identification of oleaginous yeasts that metabolize aromatic compounds

The valorization of lignin is critical for the economic viability of the bioeconomy. Microbial metabolism is advantageous for handling the myriad of aromatic compounds resulting from lignin chemical or enzymatic depolymerization. Coupling aromatic metabolism to fatty acid biosynthesis makes possible the production of biofuels, oleochemicals, and other fine/bulk chemicals derived from lignin. Our previous work identified Cutaneotrichosporon oleaginosus as a yeast that could accumulate nearly 70% of its dry cell weight as lipids using aromatics as a sole carbon source. Expanding on this, other oleaginous yeast species were investigated for the metabolism of lignin-relevant monoaromatics. Thirty-six oleaginous yeast species from the Phaff yeast collection were screened for growth on several aromatic compounds representing S-, G-, and H- type lignin. The analysis reported in this study suggests that aromatic metabolism is largely segregated to the Cutaenotrichosporon, Trichosporon, and Rhodotorula clades. Each species tested within each clade has different properties with respect to the aromatics metabolized and the concentrations of aromatics tolerated. The combined analysis suggests that Cutaneotrichosporon yeast are the best suited to broad spectrum aromatic metabolism and support its development as a model system for aromatic metabolism in yeast.

Urea-aromatic interactions in biology

Noncovalent interactions are key determinants in both chemical and biological processes. Among such processes, the hydrophobic interactions play an eminent role in folding of proteins, nucleic acids, formation of membranes, protein-ligand recognition, etc.. Though this interaction is mediated through the aqueous solvent, the stability of the above biomolecules can be highly sensitive to any small external perturbations, such as temperature, pressure, pH, or even cosolvent additives, like, urea-a highly soluble small organic molecule utilized by various living organisms to regulate osmotic pressure. A plethora of detailed studies exist covering both experimental and theoretical regimes, to understand how urea modulates the stability of biological macromolecules. While experimentalists have been primarily focusing on the thermodynamic and kinetic aspects, theoretical modeling predominantly involves mechanistic information at the molecular level, calculating atomistic details applying the force field approach to the high level electronic details using the quantum mechanical methods. The review focuses mainly on examples with biological relevance, such as (1) urea-assisted protein unfolding, (2) urea-assisted RNA unfolding, (3) urea lesion interaction within damaged DNA, (4) urea conduction through membrane proteins, and (5) protein-ligand interactions those explicitly address the vitality of hydrophobic interactions involving exclusively the urea-aromatic moiety.

Probing the side chain tolerance for inhibitors of the CD95/PLCγ1 interaction

Proceeding our effort to study protein-protein interaction between the death receptor CD95 and phospholipase PLCγ1, we present in the current work chameleon-like traits of peptidomimetic inhibitors. Minute analysis of the interaction suggests that most of the binding energy relies on van der Waals contacts rather than more specific features, such as hydrogen bonds or salt bridges. The two most important positions of the peptoid for its interaction with PLCγ1 (Arg184 and Arg187) were modified to test this hypothesis. While Arg184 proves to be exchangeable for Trp, with no alteration in affinity, the nature of the amino acid replacing Arg187 is more dependent on its positive charge. However, affinity can be partially recovered by increasing van der Waals interactions. Overall, this study shows that for both positions, a subtle balance exists between hydrophobicity, surface contacts and affinity for CD95/PLCγ1, and provides information for the generation of new therapeutic compounds toward this druggable target.

Application of the combinatorial approaches of medicinal and aromatic plants with nanotechnology and its impacts on healthcare

BACKGROUND

Medicinal and aromatic plants are natural raw materials. Since ancient times these herbal materials are being commonly used as herbal drugs, food products, and cosmetics. The phytomolecules isolated from the medicinal and aromatic plants (MAPs) are in high demand specifically in drug industries. However, these phytomolecules have certain limitations of low absorption, high toxicity, and other side effects, bioavailability and efficacy. These limitations may be overcome by using nanotechnological tools. The plant extract or essential oil of MAPs are also useful in the synthesis of nanoparticles. In future this combinatorial application of MAPs and nanotechnology would be advantageous in the healthcare area.

METHODS

Literature search was performed using databases like Pubmed, Scopus and Google Scholar with the keywords "nanoparticles," "phytomolecules," "medicinal and aromatic plants" and "green synthesis of nanoparticles" in the text.

RESULT

Phytomolecules of medicinal and aromatic plants like curcumin, camptothecin, thymol, and eugenol have certain limitations of bioavailability, efficacy, and solubility. It limits its biological activity and therefore application in the biomedical area. The increment in the biological activity and sustained delivery was observed after the encapsulation of these potent phytomolecules encapsulated in the nanocarriers. Besides, MAPs and/or their molecules/oils mediate the synthesis of metal nanocarriers with less toxicity.

CONCLUSION

This review highlights the impact of the combination of the MAPs with the nanotechnology along with the challenges. It would be an effective technique for the efficient delivery of different phytomolecules and also in the synthesis of novel nano-materials, which escalates the opportunity of exploration of potential molecules of MAPs. Graphical abstract Graphical representation of the combinatorial approach of MAPs and nanotechnology.

Expression of benzoyl-CoA metabolism genes in the lignocellulolytic host Caldicellulosiruptor bescii

Genes responsible for the anaerobic catabolism of benzoate in the thermophilic archaeon Ferroglobus placidus were expressed in the thermophilic lignocellulose-degrading bacterium Caldicellulosiruptor bescii, as a first step to engineering this bacterium to degrade this lignin metabolite. The benzoyl-CoA ligase gene was expressed individually, and in combination with benzoyl-CoA reductase and a putative benzoate transporter. This effort also assessed heterologous expression from a synthetically designed operon whereby each coding sequence was proceeded by a unique C. bescii ribosome binding site sequence. The F. placidicus benzoyl-CoA ligase gene was expressed in C. bescii to produce a full-length protein with catalytic activity. A synthetic 6-gene operon encoding three enzymes involved in benzoate degradation was also successfully expressed in C. bescii as determined by RNA analysis, though the protein products of only four of the genes were detected. The discord between the mRNA and protein measurements, especially considering the two genes lacking apparent protein abundance, suggests variable effectiveness of the ribosome binding site sequences utilized in this synthetic operon. The engineered strains did not degrade benzoate. Although the heterologously expressed gene encoding benzoyl-CoA ligase yielded a protein that was catalytically active in vitro, expression in C. bescii of six benzoate catabolism-related genes combined in a synthetic operon yielded mixed results. More effective expression and in vivo activity might be brought about by validating and using different ribosome binding sites and different promoters. Expressing additional pathway components may alleviate any pathway inhibition and enhance benzoyl-CoA reductase activity.

Terpene core in selected aromatic and edible plants: Natural health improving agents

Aromatic plants synthesize and produce aromatic molecules, among these compounds some of them belong to terpenes and terpenoids. Plant species have specific genes involved in secondary metabolism which allows them to synthesize various compounds with terpene core. These kinds of plant species are also known as herbal drugs and they are primarily used as components in medicinal products or simply as health foods. This chapter will focus on terpene and terpenoid compounds found in selected edible and aromatic plants belonging to several plant families. Selected plant species are briefly discussed. Biologically active compounds with terpene core are most frequently found in essential oils of the edible and aromatic species, as well as they are separately isolated and identified from the extracts. Health beneficial effects coming from terpene compounds found in edible and aromatic plants are further presented and include antimicrobial, antiviral, cytotoxic, anticancer, anti-inflammatory and many other pharmacological activities.

Naturally occurring aromatic steroids and their biological activities

The present review describes the distribution and biological activities of natural mono-, di-, and triaromatic steroids. It is shown that the producers of aromatic steroids are microorganisms, fungi, and marine invertebrates, and also they were found in plants, animals, marine sediments, and karst deposits. Eighty biologically active aromatic steroids likely have an anti-tumor, anti-inflammatory, and neuroprotection activity with a confidence of 78 to 92%. The structures and predicted biological activities of aromatic steroids are available. This review emphasizes the role of aromatic steroids as an important source and potential leads for drug discovery and they are of great interest to chemists, physicians, biologists, pharmacologists, and the pharmaceutical industry.

Biology, propagation and utilization of elite coconut varieties (makapuno and aromatics)

Coconut farming is not only a vital agricultural industry for all tropical countries possessing humid coasts and lowlands, but is also a robust income provider for millions of smallholder farmers worldwide. However, due to its longevity, the security of production of this crop suffers significantly from episodes of natural disasters, including cyclone and tsunami, devastating pest and disease outbreaks, while also affected by price competition for the principal products, especially the oil. In order to reduce these pressures, high-value coconut varieties (makapuno and aromatics) have been introduced in some regions, on a limited scale, but with positive outcomes. Even though these two varieties produce fruit with delicious solid or flavoursome liquid endosperm, their distinct biochemical and cellular features unfortunately prevent their in situ germination. In fact, embryo rescue and culture have been developed historically to nurture the embryo under in vitro conditions, enabling effective propagation. In an attempt to provide a comprehensive review featuring these elite coconut varieties, this paper firstly introduces their food values and nutritional qualities, and then discusses the present knowledge of their biology and genetics. Further possibilities for coconut in general are also highlighted, through the use of advanced tissue culture techniques and efficient seedling management for sustainable production of these highly distinct and commercially attractive varieties of coconut.

Linear solvation energy relationships (LSER) for adsorption of organic compounds by carbon nanotubes

The objective of this paper was to create a comprehensive database for the adsorption of organic compounds by carbon nanotubes (CNTs) and to use the Linear Solvation Energy Relationship (LSER) technique for developing predictive adsorption models of organic compounds (OCs) by multi-walled carbon nanotubes (MWCNTs) and single-walled carbon nanotubes (SWCNTs). Adsorption data for 123 OCs by MWCNTs and 48 OCs by SWCNTs were compiled from the literature, including some experimental results obtained in our laboratory. The roles of selected OCs properties and CNT types were examined with LSER models. The results showed that the r(2) values of the LSER models displayed small variability for aromatic compounds smaller than 220 g/mol, after which a decreasing trend was observed. The data available for aliphatics was mainly for molecular weights smaller than 250 g/mol, which showed a similar trend to that of aromatics. The r(2) values for the LSER model on the adsorption of aromatic and aliphatic OCs by SWCNTs and MWCNTs were relatively similar indicating the linearity of LSER models did not depend on the CNT types. Among all LSER model descriptors, V term (molecular volume) for aromatic OCs and B term (basicity) for aliphatic OCs were the most predominant descriptors on both type of CNTs. The presence of R term (excess molar refractivity) in LSER model equations resulted in decreases for both V and P (polarizability) parameters without affecting the r(2) values. Overall, the results demonstrate that successful predictive models can be developed for the adsorption of OCs by MWCNTs and SWCNTs with LSER techniques.

Characterisation of waste derived biochar added biocomposites: chemical and thermal modifications

A step towards sustainability was taken by incorporating waste based pyrolysed biochar in wood and polypropylene biocomposites. The effect of biochar particles on the chemistry and thermal makeup of the composites was determined by characterising them through an array of characterisation techniques such as 3D optical profiling, X-ray diffraction, transmission electron microscopy, electron spin/nuclear magnetic resonance spectroscopy, and differential scanning calorimetry. It was observed that addition of biochar increased the presence of free radicals in the composite while also improving its thermal conductivity. Biochar particles did not interfere with the melting behaviour of polymer in the thermal regime. However, wood and biochar acted as nucleation agents consequently increasing the crystallisation temperature. The crystal structure of polypropylene was not disrupted by biochar inclusion in composite. Transmission electron microscopy images illustrated the aggregated nature of the biochar particles at higher loading levels. Nuclear magnetic resonance studies revealed the aromatic nature of biochar and the broadening of peak intensities of composites with increasing biochar levels due to its amorphous nature and presence of free radicals. Thus, this insight into the chemical and thermal modification of biochar added composites would allow effective engineering to optimise their properties while simultaneously utilising wastes.

Comprehensive spectroscopic studies on the interaction of biomolecules with surfactant detached multi-walled carbon nanotubes

This paper investigates the interaction of ten diverse biomolecules with surfactant detached Multi-Walled Carbon Nanotubes (MWCNTs) using multiple spectroscopic methods. Declining fluorescence intensity of biomolecules in combination with the hyperchromic effect in UV-Visible spectra confirmed the existence of the ground state complex formation. Quenching mechanism remains static and non-fluorescent. 3D spectral data of biomolecules suggested the possibilities of disturbances to the aromatic microenvironment of tryptophan and tyrosine residues arising out of CNTs interaction. Amide band Shifts corresponding to the secondary structure of biomolecules were observed in the of FTIR and FT-Raman spectra. In addition, there exists an increased Raman intensity of tryptophan residues of biomolecules upon interaction with CNTs. Hence, the binding of the aromatic structures of CNTs with the aromatic amino acid residues, in a particular, tryptophan was evidenced. Far UV Circular spectra have showed the loss of alpha-helical contents in biomolecules upon interaction with CNTs. Near UV CD spectra confirmed the alterations in the tryptophan positions of the peptide backbone. Hence, our results have demonstrated that the interaction of biomolecules with OH-MWCNTs would involve binding cum structural changes and alteration to their aromatic micro-environment.

Phenotypic characters of rice landraces reveal independent lineages of short-grain aromatic indica rice

Rice landraces are lineages developed by farmers through artificial selection during the long-term domestication process. Despite huge potential for crop improvement, they are largely understudied in India. Here, we analyse a suite of phenotypic characters from large numbers of Indian landraces comprised of both aromatic and non-aromatic varieties. Our primary aim was to investigate the major determinants of diversity, the strength of segregation among aromatic and non-aromatic landraces as well as that within aromatic landraces. Using principal component analysis, we found that grain length, width and weight, panicle weight and leaf length have the most substantial contribution. Discriminant analysis can effectively distinguish the majority of aromatic from non-aromatic landraces. More interestingly, within aromatic landraces long-grain traditional Basmati and short-grain non-Basmati aromatics remain morphologically well differentiated. The present research emphasizes the general patterns of phenotypic diversity and finds out the most important characters. It also confirms the existence of very unique short-grain aromatic landraces, perhaps carrying signatures of independent origin of an additional aroma quantitative trait locus in the indica group, unlike introgression of specific alleles of the BADH2 gene from the japonica group as in Basmati. We presume that this parallel origin and evolution of aroma in short-grain indica landraces are linked to the long history of rice domestication that involved inheritance of several traits from Oryza nivara, in addition to O. rufipogon. We conclude with a note that the insights from the phenotypic analysis essentially comprise the first part, which will likely be validated with subsequent molecular analysis.

Aromatic borozene

Based on our comprehensive theoretical investigation and known experimental results for small boron clusters, we predict the existence of a novel aromatic inorganic molecule, B12H6. This molecule, which we refer to as borozene, has remarkably similar properties to the well-known benzene. Borozene is planar, possesses a large first excitation energy, D3hsymmetry, and more importantly is aromatic. Furthermore, the calculated anisotropy of the magnetic susceptibility of borozene is three times larger in absolute value than for benzene. Finally, we show that borozene molecules may be fused together to give larger aromatic compounds with even larger anisotropic susceptibilities.