Small Volatile Molecules Research Articles

Current commercial reactive and polymeric flame retardants in polyurethane foams

Polyurethane foams encompass a wide range of materials which, depending on the foam structure, chemical composition, and presence of flame retardants, can be very combustible or fire resistant. The first commercial flame retardants for polyurethane foams were developed 60 years ago with a focus on fire retardant efficiency. These legacy flame retardants are relatively small volatile molecules that can migrate from the foam to the environment. Now the flame retardant industry has been changing with a focus on reactive or polymeric flame retardants. This article gives a short overview of these new commercial flame retardants.

Boosting Efficient Ammonium Rejection and Water Evaporation Rate by Solar‐Driven Hydrogel Evaporation

Solar‐driven evaporation using hydrogels and photothermal materials is a promising freshwater harvesting technology. However, due to the difficulty of removing volatile pollutants through evaporation and the fact that the evaporation efficiency has reached its limit, further improving efficiency becomes challenging. Therefore, a material simultaneously possessing low water evaporation enthalpy as well as the ability to inhibit volatile pollutants is desired. In this work, a dense inhibitory layer on the hydrogel framework of polyacrylamide introduced into polyvinyl alcohol is designed to enhance its suppression of volatile pollutants and regulate the water state. This not only reduces the energy demand for evaporation but also makes it more effective in treating wastewater containing volatile pollutant ammonia nitrogen. Finally, a high evaporation rate of 3.0 kg m−2 h−1 and an excellent ammonium rejection rate of 90% for high concentration ammonia wastewater are obtained under 1 kW m−2 illumination. This work opens up new avenues of application for the use of photothermal materials in the use of clean solar energy for the separation of freshwater and volatile small molecules.

The physiological roles of anoctamin2/TMEM16B and anoctamin1/TMEM16A in chemical senses

Chemical senses allow animals to detect and discriminate a vast array of molecules. The olfactory system is responsible of the detection of small volatile molecules, while water dissolved molecules are detected by taste buds in the oral cavity. Moreover, many animals respond to signaling molecules such as pheromones and other semiochemicals through the vomeronasal organ. The peripheral organs dedicated to chemical detection convert chemical signals into perceivable information through the employment of diverse receptor types and the activation of multiple ion channels. Two ion channels, TMEM16B, also known as anoctamin2 (ANO2) and TMEM16A, or anoctamin1 (ANO1), encoding for Ca2+-activated Cl¯ channels, have been recently described playing critical roles in various cell types. This review aims to discuss the main properties of TMEM16A and TMEM16B-mediated currents and their physiological roles in chemical senses. In olfactory sensory neurons, TMEM16B contributes to amplify the odorant response, to modulate firing, response kinetics and adaptation. TMEM16A and TMEM16B shape the pattern of action potentials in vomeronasal sensory neurons increasing the interspike interval. In type I taste bud cells, TMEM16A is activated during paracrine signaling mediated by ATP. This review aims to shed light on the regulation of diverse signaling mechanisms and neuronal excitability mediated by Ca-activated Cl¯ channels, hinting at potential new roles for TMEM16A and TMEM16B in the chemical senses.

Adsorption Affinities of Small Volatile Organic Molecules on Graphene Surfaces for Novel Nanofiller Design: A DFT Study.

The adsorption of organic molecules on graphene surfaces is a crucial process in many different research areas. Nano-sized carbon allotropes, such as graphene and carbon nanotubes, have shown promise as fillers due to their exceptional properties, including their large surface area, thermal and electrical conductivity, and potential for weight reduction. Surface modification methods, such as the "pyrrole methodology", have been explored to tailor the properties of carbon allotropes. In this theoretical work, an ab initio study based on Density Functional Theory is performed to investigate the adsorption process of small volatile organic molecules (such as pyrrole derivatives) on graphene surface. The effects of substituents, and different molecular species are examined to determine the influence of the aromatic ring or the substituent of pyrrole's aromatic ring on the adsorption energy. The number of atoms and presence of π electrons significantly influence the corresponding adsorption energy. Interestingly, pyrroles and cyclopentadienes are 10 kJ mol-1 more stable than the corresponding unsaturated ones. Pyrrole oxidized derivatives display more favorable supramolecular interactions with graphene surface. Intermolecular interactions affect the first step of the adsorption process and are important to better understand possible surface modifications for carbon allotropes and to design novel nanofillers in polymer composites.

Controllable Structural Transformation of Non-Porous Propyl-Malonate Hexakis[60]fullerene by Chloroform Uptake/Release.

The design of dynamic structures with high recognition host-guest materials capable to host selectively small volatile molecules is an emergent field of research with both fundamental and applied implications. The challenge of exploring novel materials with advanced functionalities has led to the development of dynamic crystalline structures promoted by soft interactions. Here, a new pure organic dynamic framework based on hexakis[60]fullerene that are held together by weak van der Waals interactions is described. This crystalline structure is capable of absorbing and releasing chloroform, through internal structural reorganization. This research provides new insight into the design of organic molecular crystals for selective adsorption applications.

Small volatile lipophilic molecules induced belowground by aphid attack elicit a defensive response in neighbouring un-infested plants.

In pioneering studies on plant-aphid interactions, we have observed that Vicia faba plants infested by aphids can transmit signals via the rhizosphere that induce aboveground defence in intact, neighbouring plants. The aphid parasitoid Aphidius ervi is significantly attracted towards intact broad bean plants grown in a hydroponic solution previously harbouring Acyrtosiphon pisum-infested plants. To identify the rhizosphere signal(s) possibly mediating this belowground plant-plant communication, root exudates were collected using Solid-Phase Extraction (SPE) from 10-day old A. pisum-infested and un-infested Vicia faba plants hydroponically grown. To verify the ability of these root exudates to trigger defence mechanisms against the aphids we added them to V. fabae plants grown in hydroponic solution, and tested these plants in the wind-tunnel bioassay to assess their attractiveness towards the aphids' parasitoids A. ervi. We identified three small volatile lipophilic molecules as plant defence elicitors: 1-octen-3-ol, sulcatone and sulcatol, in SPE extracts of A. pisum-infested broad bean plants. In wind tunnel assays, we recorded a significant increase in the attractiveness towards A. ervi of V. faba plants grown in hydroponic solution treated with these compounds, compared to plants grown in hydroponic treated with ethanol (control). Both 1-octen-3-ol and sulcatol have asymmetrically substituted carbon atoms at positions 3 and 2, respectively. Hence, we tested both their enantiomers alone or in mixture. We highlighted a synergistic effect on the level of attractiveness towards the parasitoid when testing the three compounds together in respect to the response recorded against them singly tested. These behavioural responses were supported by the characterization of headspace volatiles released by tested plants. These results shed new light on the mechanisms underlying plant-plant communication belowground and prompt the use of bio-derived semiochemicals for a sustainable protection of agricultural crops.

Molecular Characterization of Hydrocarbons in Petroleum by Ultrahigh-Resolution Mass Spectrometry

The progress in ultrahigh-resolution mass spectrometry (UHRMS) and related technologies has significantly promoted the development of petroleomics. The study of petroleomics has greatly broadened our knowledge of the composition of petroleum at the molecular level, especially heavy fractions that cannot be analyzed by gas chromatography (GC)-based methods. To date, heteroatom-containing (O, N, S, and metal atoms) compounds in petroleum have been studied extensively by UHRMS. Nevertheless, the main components of petroleum, hydrocarbon compounds, have remained out of reach of petroleomics characterization for a long time because they are too difficult to be softly and efficiently ionized for UHRMS analysis. It is undoubtedly the case that petroleum hydrocarbons should not be the missing part of petroleomics characterization since they play important roles not only as feeding pools for various high value-added petroleum products but also as critical biomarkers for geochemistry studies. Here, the most recent breakthroughs in petroleomics characterization of hydrocarbon compounds using UHRMS rather than conventional methods have been reviewed. Innovations of soft ionization methods can transform non-polar hydrocarbon molecules into molecular ions or quasi-molecular ions that are reachable for UHRMS without fragmentation. The development of data processing methods has assisted the decoding of the complicated UHRMS data to visualize the molecular composition and structure of hydrocarbon compounds. These advances make it possible to see the whole picture of petroleum compositions, from light distillation fractions to heavy distillation fractions, and from small volatile molecules to large non-volatile ones. The applications of UHRMS-based methods for petroleomics characterization of hydrocarbon compounds in crude oils and various petroleum samples including fuel oil, slurry, and even asphaltene have made a great contribution to petrochemistry and geochemistry studies, especially in the fields of molecular refining and biomarker discovery.

Auramine O UV Photocatalytic Degradation on TiO2 Nanoparticles in a Heterogeneous Aqueous Solution

Amongst the environmental issues throughout the world, organic synthetic dyes continue to be one of the most important subjects in wastewater remediation. In this paper, the photocatalytic degradation of the dimethylmethane fluorescent dye, Auramine O (AO), was investigated in a heterogeneous aqueous solution with 100 nm anatase TiO2 nanoparticles (NPs) under 365 nm light irradiation. The effect of irradiation time was systematically studied, and photolysis and adsorption of AO on TiO2 NPs were also evaluated using the same experimental conditions. The kinetics of AO photocatalytic degradation were pseudo-first order, according to the Langmuir–Hinshelwood model, with a rate constant of 0.048 ± 0.002 min−1. A maximum photocatalytic efficiency, as high as 96.2 ± 0.9%, was achieved from a colloidal mixture of 20 mL (17.78 μmol L−3) AO solution in the presence of 5 mg of TiO2 NPs. The efficiency of AO photocatalysis decreased nonlinearly with the initial concentration and catalyst dosage. Based on the effect of temperature, the activation energy of AO photocatalytic degradation was estimated to be 4.63 kJ mol−1. The effect of pH, additional scavengers, and H2O2 on the photocatalytic degradation of AO was assessed. No photocatalytic degradation products of AO were observed using UV–visible and Fourier transform infrared spectroscopy, confirming that the final products are volatile small molecules.

Organic Carbonyls Are Poor Biosignature Gases in Exoplanet Atmospheres but May Generate Significant CO

The search for signs of life beyond Earth is a crucial driving motivation of exoplanet science, fueling new work on biosignature gases in habitable exoplanet atmospheres. We study carbonyls, a category of molecules containing the C=O double bond, following our proposal to systematically identify plausible biosignature gas candidates from a list of all small volatile molecules. We rule out carbonyls as biosignature gases due to both their high water solubility and their high photolysis rate, despite their ubiquitous production by life on Earth, their critical importance in Earth’s life biochemistry, and their uniquely identifiable molecular spectral features in mid- to low-resolution spectroscopy. Even in scenarios where life is a large net source of carbonyls, we demonstrate that detection of carbonyls is not possible on even the most ideal habitable exoplanet, because only 10 ppb of carbonyls can accumulate under our most optimistic assumptions. Moreover, high biological fluxes of organic carbon gases, while mathematically possible, are likely biologically unattainable due to the resulting huge waste of carbon—a main building block for life. Our simulations show that photochemical processing of carbonyls leads to generation of CO in quantities that can reengineer the atmosphere, affirming the ambiguity of CO as an antibiosignature. Overall, we find that the expression of a carbonyl-producing biosphere by CO, though potentially detectable by the James Webb Space Telescope, is unable to be uniquely traced back to carbonyls. While carbonyls fail as a bioindicator, by investigating them we have made a significant step toward systematically assessing the biosignature gas potential of all small volatile molecules.

Chemogenetics defines a short-chain fatty acid receptor gut-brain axis.

Volatile small molecules, including the short-chain fatty acids (SCFAs), acetate and propionate, released by the gut microbiota from the catabolism of nondigestible starches, can act in a hormone-like fashion via specific G-protein-coupled receptors (GPCRs). The primary GPCR targets for these SCFAs are FFA2 and FFA3. Using transgenic mice in which FFA2 was replaced by an altered form called a Designer Receptor Exclusively Activated by Designer Drugs (FFA2-DREADD), but in which FFA3 is unaltered, and a newly identified FFA2-DREADD agonist 4-methoxy-3-methyl-benzoic acid (MOMBA), we demonstrate how specific functions of FFA2 and FFA3 define a SCFA-gut-brain axis. Activation of both FFA2/3 in the lumen of the gut stimulates spinal cord activity and activation of gut FFA3 directly regulates sensory afferent neuronal firing. Moreover, we demonstrate that FFA2 and FFA3 are both functionally expressed in dorsal root- and nodose ganglia where they signal through different G proteins and mechanisms to regulate cellular calcium levels. We conclude that FFA2 and FFA3, acting at distinct levels, provide an axis by which SCFAs originating from the gut microbiota can regulate central activity.

Porous nickel and cobalt hexanuclear ring-like clusters built from two different kind of calixarene ligands – new molecular traps for small volatile molecules

The formation and structural analysis of porous hexanuclear ring-like cluster complexes built from two different kind of calixarene ligands is presented, together with their stability and vapor solvent sorption properties.

Highly charged hydrogel with enhanced donnan exclusion toward ammonium for efficient solar-driven water remediation

Developing solar-driven photothermal materials with superior rejection capability toward volatile ammonium (NH4+) is a huge challenge but rather important for agricultural/municipal wastewater remediation. Herein, different from common hierarchical porosity designs, a positive charge-assisted Janus hydrogel evaporator with enhanced Donnan exclusion toward ammonium is uniquely achieved without sacrificing the water evaporation capability. The ammonium diffusion resistance of the so-fabricated Janus evaporator is significantly increased by optimizing the charge density and diffusion distance, yielding a high ammonium rejection rate up to 95%, which is never reported before. Meanwhile, the Janus evaporator also yields a water evaporation rate up to 3.3 kg m−2h−1 for the natural wastewater via partial amorphization of cellulose Iα allomorph, which is ∼3 times faster than the previous photothermal materials for intercepting volatile phenol molecules. This work points out new avenues for the application of photothermal materials in separating freshwater from small volatile molecules using clean solar energy.

Odorant-binding proteins in canine anal sac glands indicate an evolutionarily conserved role in mammalian chemical communication

BackgroundChemical communication is an important aspect of the behavioural ecology of a wide range of mammals. In dogs and other carnivores, anal sac glands are thought to convey information to conspecifics by secreting a pallet of small volatile molecules produced by symbiotic bacteria. Because these glands are unique to carnivores, it is unclear how their secretions relate to those of other placental mammals that make use of different tissues and secretions for chemical communication. Here we analyse the anal sac glands of domestic dogs to verify the secretion of proteins and infer their evolutionary relationship to those involved in the chemical communication of non-carnivoran mammals.ResultsProteomic analysis of anal sac gland secretions of 17 dogs revealed the consistently abundant presence of three related proteins. Homology searches against online databases indicate that these proteins are evolutionary related to ‘odorant binding proteins’ (OBPs) found in a wide range of mammalian secretions and known to contribute to chemical communication. Screening of the dog’s genome sequence show that the newly discovered OBPs are encoded by a single cluster of three genes in the pseudoautosomal region of the X-chromosome. Comparative genomic screening indicates that the same locus is shared by a wide range of placental mammals and that it originated at least before the radiation of extant placental orders. Phylogenetic analyses suggest a dynamic evolution of gene duplication and loss, resulting in large gene clusters in some placental taxa and recurrent loss of this locus in others. The homology of OBPs in canid anal sac glands and those found in other mammalian secretions implies that these proteins maintained a function in chemical communication throughout mammalian evolutionary history by multiple shifts in expression between secretory tissues involved in signal release and nasal mucosa involved in signal reception.ConclusionsOur study elucidates a poorly understood part of the biology of a species that lives in close association with humans. In addition, it shows that the protein repertoire underlying chemical communication in mammals is more evolutionarily stable than the variation of involved glands and tissues would suggest.

Effect of the epichlorohydrin grafting of starch on its pyrolysis behavior and mechanism

Crosslinking is a common method for preparing biomass-based carbon materials. Corn starch grafted with epichlorohydrin was prepared and then stabilized and carbonized to obtain starch-based near-spherical carbon materials. The pyrolysis of corn starch under the influence of epichlorohydrin was analyzed by TG-MS, and the micro-morphology and crystal structure of the near-spherical carbon materials were characterized by SEM and XRD. The surface chemical evolution of the starch before and after pyrolysis was characterized by in-situ FTIR. The modified starch pyrolysis and the cross-linking reactions between epichlorohydrin and starch were investigated. Results indicate that for the modified starch the temperature at which the weight loss rate is a maximum is lowered so that the pyrolysis is relatively mild, and the destruction of the basic skeleton is reduced and the carbon yield greatly increased compared with pristine starch. The cross-linked starch tends to transform to aromatic structures in pyrolysis, the carbonization degree of the hydrolysate is improved, and the yield of the final product is increased compared to the non-crosslinked material. During pyrolysis, epichlorohydrin cross-links with starch to form a network structure, which stabilizes the starch skeleton, thus reducing the production of volatile small molecules.

In-situ catalytic conversion of coal pyrolysis gas to nanoporous carbon rods and superior sodium ion storage performance

Pyrolysis is the primary step for many coal conversion and utilization technologies such as combustion, gasification, activation and cascade utilization. To increase the utilization value of coal pyrolysis gas, this study explores an efficient solution by in-situ conversion of pyrolysis gas into a new type of nanoporous carbon rods, which deliver an excellent performances as a sodium ion battery anode. The conversion was achieved by an MgO-assisted chemical vapor deposition (CVD) process, in which abundant small organic gases (i.e., CH4 and C2 ~ C3) and volatile molecules condensable at ambient temperature during bituminous coal pyrolysis could be effectively catalytically deposited onto MgO template and further converted to solid carbon under high temperatures. A series of characterizations of solid, liquid and gaseous products obtained with or without MgO-assisted CVD demonstrated the successful conversion of pyrolysis gas into functional solid carbon while reducing the yield of undesired coal tar. The obtained nanoporous carbon rods (NPCR-850) inherited the rod-like morphology of MgO templates and showed multiple structural merits, including a hierarchical pore configuration with abundant mesopores, good structural stability, and a low oxygen content. When employed as an anode for sodium ion storage, NPCR-850 anodes could maintain a high reversible capacity of 181 mA h g−1 at 0.2 A g−1 even after 2000 charge/discharge cycles, corresponding to an outstanding capacity retention of 90%. This study proves the feasibility of the conversion of pyrolysis gas to high-value solid carbon materials and provides a facile pathway to synthesis nanoporous carbon rods for electrochemical Na+ storage.

Molecular characteristics of volatile components from willow bark

Willow (Salix matsudana) bark is the bark of willow trees, it is rich in resources. Extracting these resources becomes difficult due to the relative lack of systematic and in-depth analysis of the total chemical composition. Analysis was performed using TDS-GC/MS, TG, FTIR and PY-GC/MS techniques. Results and discussion: the extracts form volatile organic compounds are mainly included in the analysis of TDS-GC/MS, such as, organic acids, exters, alcohols, etc. Extracts are rich in VOCs:1,2-Benzenedicarboxylic acid, bis(2-methylpropyl) ester, its function is mainly as plasticizer. FTIR analysis are further confirmed, the ingredients of total extracts include ethers, The treatment of total heat loss is divided into two distinct phases: the first phase of 50 °C to 100 °C, the second phase of 150 °C to 250 °C, the sequence of quality loss is the second and the first stage, important turning point temperature is 245 °C, with significant changes in quality, for example, high polymer pyrolysis into small volatile molecules. In addition, various pyrolysis VOCs have been analyzed by PY-GC/MS, And have good development space, such as, Carbamic acid, monoammonium salt (4.80%), Glycolaldehyde dimer (4.04%), Catechol (0.44%). etc. Both of them have good development prospects, including many new chemical components produced by the pyrolysis of total extracts and residues, which is a new method to provide high quality applications.

Microwave‐assisted extraction (MAE) combined with gas chromatography–mass spectrometry (GC–MS) for determination of volatile small molecules to evaluate compatibility of antimicrobial peptide PL‐5 spray with packaging materials

A simple and efficient method involving microwave-assisted extraction (MAE) combined with GC-MS was established to determine 1,3-di-tert-butylbenzene (DBB), 2,4-di-tert-butylphenol (DBP), 3,5-di-tert-butyl-4-hydroxybenzaldehyde (DBHBA) for evaluating the compatibility of antimicrobial peptide PL-5 spray with drug-packaging materials. In this study, the antimicrobial peptide PL-5 spray was purified using a Welchrom C18 column, and the high-density polyethylene spray bottle with liquid collection tube was first mixed with absolute ethanol, which would be subjected to MAE for further measurement by GC-MS. Various experimental parameters were systematically optimized, and good linearities were obtained within the range of 0.05-1.00 μg/mL for DBB and DBHBA and 0.50-10.00 μg/mL for DBP, with limits of detection (LODs) of 0.99 ng/mL (DBB), 16.34 ng/mL (DBP), and 1.64 ng/mL (DBHBA). Satisfactory recoveries that ranged from 96.0% to 107.2% were acquired, and the relative standard deviation was ≤ 4.7%. The results showed that the maximum daily usage of DBB, DBP, and DBHBA was 9.859, 163.445, and 16.399 ng, respectively, which was far below the corresponding permitted daily exposure values according to the safety assessment, indicating that the migration of analytes did not bring any potential safety risk. The compatibility between the drug and the packaging materials was favorable.

Molecular characteristics of Salix cheilophila chemical components

Salix cheilophila plays a role in sand control. However, due to the lack of systematic and in-depth analysis on the chemical composition of Salix chei lophila, it is difficult to develop higher-value products, resulting in low efficiency or even outright abandonment. In this paper, the components of Salix cheilophila and its change rule before/after extraction were introduced, and the thermal loss rules and pyrolysis properties of Salix cheilophila were also explained. The analytic result of FT-IR further confirmed that: the Salix cheilophila contains components including esters, aldehydes, alcohols and ethers, etc., and the organic solvent extraction does not made compound groups of Salix cheilophila significantly changed. There are four obvious stages in thermal loss treatment of Salix cheilophila. During thermal loss treatment, three critical turning points of temperature (44?C, 78?C, and 219?C) were observed, accompanied by significantly chemical changes such as macromolecule pyrolyzed into small volatile molecules. The pyrolysis products of Salix cheilophila extractive including esters, acid, alcohols, aldehyde, ethers, alkene, ammonium, anhydride, phenols, ketone, furans and heterocyclic compounds. There were quite differences among properties and functions of the components. Thus, the application prospects were also significantly different.

Chemical components of Choerospondias axillaris wood by TD-GC/MS, Py-GC/MS, and TG

Choerospondias axillaris is a better fast-growing species. Its bark and fruit have the functions of anti-inflammation, detoxification, hemostasis and treatment of external burns. However, due to the lack of systematic and in-depth analysis of the chemical composition of Choerospondias axillaris, it is difficult to develop high value-added products, resulting in low processing efficiency and even direct abandonment. In order to improve the application value of Choerospondias axillaris and excavate its application in many fields, this paper takes Choerospondias axillaris as the research object to reveal the characteristics of volatile organic compounds and the variation rule of molecular components of jujube before and after extraction of Choerospondias axillaris. The extracts of Choerospondias axillaris were detected and identified by GC-MS and FTIR. The pyrolysis process of Choerospondias axillaris was characterized by TGA-DTG and Py-GC-MS. The volatile organic compounds in the ethanol extracts of Choerospondias axillaris were mainly alcohols, petroleum ether extracts were mainly alkanes and organic acids, and phenylethanol extracts were mainly esters. Among the three kinds of jujube extracts, nonanal, beta-caryophyllene, humus and caryophyllene oxides and other bioactive VOCs were observed. The total content of VOCs from high to low was petroleum ether extract, ethanol extract and benzene/ethanol extract. Choerospondias axillaris has three distinct stages of heat loss treatment: the first stage is 30–50°C, the second stage is 50–200°C, and the third stage is 200–247°C. During the heat loss treatment, three critical temperature turning points (50, 200 and 237) were observed, accompanied by significant chemical changes such as pyrolysis of macromolecules into small volatile molecules. By pyrolysis of the extracts and residues of Choerospondias axillaris, a large number of new components have been produced, which can be used in other industries and provide a new way for sour jujube to become a high-grade application resource.

Trap-State Passivation by Nonvolatile Small Molecules with Carboxylic Acid Groups for Efficient Planar Perovskite Solar Cells

Trap-state passivation has been validated to efficiently improve the performance of perovskite solar cells. Small volatile molecules and polymers both have the ability to reduce the trap states in ...