Organic Sulfides Research Articles

Two‐step thermal decomposition mechanism of phosphogypsum for resource utilization

AbstractIn this work, the reduction–oxidation two‐step method was used for investigating the resource utilization of phosphogypsum. The influences of different decomposition conditions were investigated, including the reducing process and oxidizing process. The reductive organic sulphide in lignite reacted with CaSO4 and improved the CaSO4 decomposition rate. High Fe2(SO4)3 content and anhydrous air flow rate promoted the formation of Fe–Ca–Ox, decreasing the CaSO4 decomposition rate. H2O derived from CH4 reacted with lignite to consume the solid reducing agent. In the reducing process, CaSO4 reacted with CH4 and lignite to form CO, CO2, H2O, and CaS. In the oxidizing process, CaS was mainly oxidized into CaO, SO2, and element S. Through a two‐step decomposition process (reduction with CH4 and oxidation with air), the decomposition temperature of phosphogypsum decreases and the decomposition efficiency is improved. Meanwhile, the residual lignite was oxidized into CO and CO2. Therefore, it is meaningful and valuable.

Effects of organic carbon and sulfide on the anammox reaction in the anoxic column in the SRDAPN process for treating high-strength wastewater

Low energy consumption treatment of high-strength wastewater is crucial in controlling groundwater pollution and eutrophication in closed waterbodies. In this study, the sulfate reduction, denitrification/anammox, and partial nitrification (SRDAPN) process, which is an effective organic carbon and nitrogen removal process with low energy consumption for low strength wastewater, was applied to treat livestock wastewater with high COD and sulfate concentration, and microbial reaction and community were examined using an anaerobic–anoxic biological filter reactor that simulates circulation from an aerobic reactor. At a total organic carbon loading rate of 2.7–5.8 kgC/m3·day, sulfate reduction and methane production occurred simultaneously in the anaerobic column of the reactor. Specifically, sulfate reduction resulted in organic matter removal rates of 38 and 26% at ambient temperature and 25 °C, respectively. Furthermore, both heterotrophic and autotrophic denitrification occurred in the anoxic column, and when the organic loading rate in the anoxic reactor was below 0.2 kgC/m3·day, 33%–37% of ammonium and 33%–34% of nitrite were removed by the anammox reaction. Heterotrophic denitrification bacteria (Thauera, Comamonas, and Denitratisoma) and sulfur denitrification bacteria (Sulfurimonas denitrificans) grew in the lower and middle parts of the anoxic column, whereas anammox bacteria (2.5% of Candidatus Brocadia at ambient temperature and 9.4% of Candidatus Kuenenia at 25 °C) grew in the upper part of the anoxic column. These results indicate that the SRDAPN process based on sulfur cycle and anammox is useful for treatment of high strength wastewater with low energy consumption.

Variation in sediment and seagrass characteristics reflect multiple stressors along a nitrogen‐enrichment gradient in a New England lagoon

AbstractWe examined concentrations of organic carbon, dissolved sulfides, total sediment sulfur, and stable sulfur isotope ratios in seagrass leaf tissues across a nitrogen‐enrichment gradient in a coastal marine ecosystem (Cape Cod, Massachusetts) in 2007–2010 and 2017–2019. We also measured seagrass aboveground and belowground biomass, epibiota biomass, and leaf chlorophyll content. Seagrasses were present at all sites in the former period but were lost at our most nitrogen‐impacted site (Snug Harbor) by 2011. In 2007–2010, sediment organic carbon and dissolved sulfides were highest in Snug Harbor and decreased along the gradient; leaf tissues depleted in 34S also indicated higher sulfide intrusion into seagrass tissues in more eutrophic areas. By 2017–2019, sediment organic carbon and pore‐water soluble sulfides had decreased in Snug Harbor, but had increased at the intermediate site, to levels found at the most impacted site prior to the seagrass die‐off. Again, leaf tissue 34S depletion reflected this pattern, indicating seagrasses were exposed to the highest sulfides at the intermediate site. The decreases in sediment organic carbon and soluble sulfides in Snug Harbor years after the loss of the seagrasses illustrate a feedback between high organic matter in seagrass beds and increasing stressors like elevated soluble sulfides in nutrient‐enriched systems. We found significant relationships between sediment conditions and seagrass responses, including greater aboveground to belowground biomass ratios, epibiota biomass, and 34S‐depleted leaves at sites with high pore‐water sulfide and highly organic sediments. Our research suggests that the reduction of anthropogenic nitrogen entering the harbor is necessary for improving sediment quality and preventing seagrass mortality.

Effect of amine type on acidic toxic gas adsorption at ambient conditions on modified CuBTC

Two amine-modified copper-based Metal Organic Frameworks (MOF (CuBTC)) of different surface chemical and textural features were synthesized and used as adsorbents of acidic toxic gases (NO2 and H2S) in both moist (71% relative humidity (R.H.)) and dry conditions. The initial and exhausted samples were characterized by nitrogen adsorption, powder X-ray diffraction, scanning electron microscopy, thermal gravimetric analysis and Fourier transform infrared spectroscopy. The addition of melamine prevented full growth of CuBTC crystals and resulted in amorphous-like particles with sizes less than 200 nm. The material was non-porous with a small surface area. When urea was used as an amine source, the resulting particles maintained the overall octahedral shape of the parent CuBTC MOF and the material was more porous than the parent MOF. While the urea-modified CuBTC sample performed well as an NO2 adsorbent in the presence of moisture, the reactivity of the melamine-modified sample and its physical properties provided a favorable environment for the removal of H2S. The incorporation of amines into the MOF structure also resulted in surface defects /open copper sites that favored the removal of toxic gases in dry conditions. The reactivity of the adsorbents with toxic gases was demonstrated by the changes in the adsorbent colors, in texture, and in surface chemistry (organic salts, complexes, sulfides and nitrates were formed).

Examining the effects of chemical cleaning, leaching, and partial dissolution on zinc and cadmium isotope fractionation in marine carbonates

The application of zinc (Zn) and cadmium (Cd) isotopes as palaeo-proxies in carbonate sediment is rapidly expanding due to their potential for tracing changes in biological productivity in the modern and past oceans. However, there are limited investigations into the chemical cleaning methods required to produce the most consistent and accurate data for these novel isotope systems. This could impact their use as palaeo-proxies to reconstruct ocean-atmosphere-climate interactions throughout Earth's history.To address this concern and expand the utility of the Zn and Cd stable isotope systems as palaeo-productivity tracers, the performance of two standard chemical cleaning protocols for acquiring robust and reliable Zn and Cd isotope datasets were assessed. These include (i) the Cd-cleaning method that uses a reductive step to selectively leach contaminating secondary iron (Fe)‑manganese (Mn) (oxyhydr)oxide coatings from the carbonate surface, and an oxidative step that is used to remove post-depositional organic matter and sulphide precipitates; and (ii) the magnesium/calcium cleaning protocol that includes an oxidative step only, leaving secondary FeMn (oxyhydr)oxide coatings largely intact. Well-preserved Holocene-, and Mesozoic-aged carbonate sediments were used to test the reliability of these two chemical cleaning methods. The Holocene samples comprised not only aliquots of bulk sediment, but also individual species of planktic and benthic foraminifera.Our results show that the best practice chemical cleaning method for retrieving consistent and accurate Zn and Cd isotope, and Zn/Ca and Cd/Ca datasets for carbonate sediments, requires both reductive and oxidative cleaning following the Cd-cleaning method. This differs from most methodological approaches applied to date that remove the reductive step from the chemical cleaning protocol and apply an oxidative step only, or no chemical cleaning at all. Inclusion of the reductive step in the chemical cleaning method typically shifts δ66Zn by ~0.1‰ lower and δ114Cd by 0.3‰ higher in the solid phase, while Zn/Ca and Cd/Ca typically decrease 2-fold. The benthic foraminifera, C. wuellerstorfi, that live in ocean bottom waters where the seawater Zn and Cd isotope composition is homogeneous display evidence of Zn and Cd isotope fractionation between seawater and carbonate on the order of 0.08 ± 0.08‰ (2SE, n = 4) and − 0.25 ± 0.13‰ (2SE, n = 4), respectively, in agreement with experimental constraints. Furthermore, evidence of Zn isotope fractionation effects are recorded in a naturally-dissolved carbonate sediment, together with laboratory-controlled carbonate dissolution experiments. Based on these results, we recommend the Cd-cleaning method and the application of Zn and Cd isotope fractionation factors to accurately reconstruct past seawater Zn and Cd isotope compositions from carbonate sediments.

Study on rare earth elements, heavy metals and organic contents in the soil of oil exploration site at Matruh Governorate, Egypt

Soil is an issue material for sustainable economic and development plans; besides it considers the most valuable natural resource in all fields of citizens' life. This study is carried out to assess the impacts of heavy metals and some organic constituents on the soil, and consequently on its pollution, in a sampling point left behind the exploration activities in a site subjected to oil and gas exploration nearby Matruh Governorate, Egypt. Moreover, it is trying to evaluate the contents of some added-value rare earth in the same area. Samples were collected from ten points in a bore at different depths starting at 13,000 feet with increasing down distance every 50 feet. The study area is located within latitude 30° 48′ to 36° 889 ̋ S and longitudes 26° 59′ to 16° 406 ̋ E. Geographically, Matruh is part of the Great Western Desert.Rare Earth Elements (REEs), Heavy Metals (HMs) and organic constituents in the soil samples were analyzed based on Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) and Fourier transform infrared spectroscopy (FT-IR). Geoaccumulation Index (Igeo), Enrichment factor (EF) and Pearson Correlation Coefficients (R) were calculated to consider the soil pollution in the studied point. Also, to evaluate the abundance of REEs and to follow the relations between those elements.The study illustrated that: the most organic soil pollutants in the oil field sewage were aliphatic and aromatic hydrocarbon, phenols, organic sulfide aliphatic acid and others. Based on the geoaccumulation Index (Igeo) and Enrichment Factor (EF) classifications, the soil quality of the studied site can be classified, in general, as class 0, (uncontaminated) to class 6, (extremely contaminated). Moreover, The potentiality of the rare earth should be subjected to intensive studies to decide their economical mining and element processing.

Polyaromatic Units Set the Albedo of Dark Extraterrestrial Materials

Abstract Primitive extraterrestrial materials are generally dark, a characteristic often associated with the presence of polyaromatic organic material and/or sulfides. We show in this study that the reflectance level measured at 0.55 μm of IDPs and some meteorites is correlated to the degree of graphitization of the polyaromatic organic matter. The reflectance level of the primitive surfaces therefore allows us to obtain information on the polyaromatic organic material present on the surface of solar system small bodies observed by remote sensing or visited by space missions. We discuss our results in view of the sample return missions Hayabusa2 and OSIRIS-REx.

Release characteristics of arsenic, selenium, lead and transformation of minerals during ashing process of coal

In this paper, two kinds of coal (Baiyinhualignite and coal usinginEzhou Power Plant) were selected to study the occurrence of heavy metals including arsenic (As), selenium (Se) and lead (Pb) in coal and their release behaviors during the ashing process. The influence of ashing conditions on the mineral conversion was also examined by the combination with the changes of minerals in coal. The burn-out temperature of the coal was determined fromthethermalweightlosscurve by extrapolation method, and then the coal sample was ashed according to the National Standard Method of China. The obtained ash samples were characterized by XRD, XRF, and TG-DTG to analyze the change characteristics of coal minerals at different ashing temperatures. The content and occurrence of As, Se and Pb in coal samples were extracted by sequential chemical extraction method. The heavy metals in the ash sample were extracted by HNO3 + HF, and the heavy metal content in the extract was detected by Inductively Coupled Plasma Mass Spectrometer (ICP-MS). The results show that the heavy metal in BYH coal is mainly As in the form of sulfide bound state, which leads to the increasing volatility of As with temperature easily. However, the heavy metal in EZ is mainly sulfide-bound Pb, which makes it easy torelease with temperature. Se in coal mainly exists in the form of organic bound state and sulfide bound state. During coal ashing, kaolin is gradually dehydroxylated into metakaolin and finally converted into mullite; pyrite is oxidized to form hematite; gypsum is dehydrated to form anhydrite. The release rate of heavy metals is greatly affected by the combustion temperature during the ashing process. High content of heavy metals in the sulfide bound state results in high release rate with increasing the temperature.

Application of Chiral Lewis Base/Brønsted Acid Synergistic Catalysis Strategy in Enantioselective Synthesis of Organic Sulfides

Application of Chiral Lewis Base/Brønsted Acid Synergistic Catalysis Strategy in Enantioselective Synthesis of Organic Sulfides

Platinum Group Metals Bonded Thiolato Sulfur Oxygenation: Photoactivity and Bioactivity

Platinum group metals mediated thiolato compounds are highly susceptible for S-centered reactivity owing to high nucleophilicity and which is enormously significant in the point of its bioactivity and photoactivity. A series of oxygenation reactions of thiolate sulfur attached with platinum metals occurred with molecular O2 in varying conditions. A variety of sulfenates and sulfinates are produced depending on nature of starting substrate thiolato and the oxygenations are facile under harshly oxygen environment. There are numerous mechanistic paths for the oxygenation of platinum metals bonded thiolate S-center unlike the oxygenation reaction of organic sulphides. It is assumed that S-oxygenation occurs via the intramolecular and intermolecular dioxygen addition pathways. A number of mysterious photo-induced sulphur oxygenation and self-sensitization reactions of metal-thiolato to analogous oxygenate are also mentioned. These compounds show enzymatic catalytic activity and remarkable bioactivity also interaction with the biomolecules like DNA, which opens a new area for the researchers for designing novel heavier metals-sulfur-oxygenates compounds as metallodrugs.

Synthesis of Hierarchical TS-1 and Its Recycling Catalytic Property for Oxidative Desulfurization

Because of its unique pore structure, good hydrothermal stability and high specific surface area, hierarchical TS-1 zeolite (HTS-1) has become an important catalyst for the deep oxidative desulfurization of fuel oils. In this work, HTS-1 has been successfully synthesized by a hydrothermal crystallization method using the C-SiO2 composite as both silicon source and mesoporous template, tetrapropylammonium hydroxide as microporous template, and tetrabutylorthotitanate as titanium source. The C-SiO2 composite is obtained by mild carbonization of the SiO2/T-40 (Tween 40) xerogel, which is prepared by the two step sol-gel method. The reaction conditions for the oxidative desulfurization (ODS) of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) over HTS-1 are optimized systematically, and the recycling performances of HTS-1 are investigated in detail. After the 15th run, HTS-1 still maintains high DBT conversion (90.6%) and 4,6-DMDBT conversion (86.0%) without deactivation. The samples before and after recycle tests are characterized by XRD, FT-IR, CHN analysis, UV-Vis and SEM techniques. The results indicate that the crystal structure and morphology of regenerated HTS-1 samples are well kept, which accounts for the good structural stability and reusability of HTS-1. In addition, active intermediates for the ODS of bulky organic sulfides over HTS-1, i.e., Ti-peroxo (Ti-OOtBu) species, are captured by the UV-Vis technique. Finally, a possible reaction mechanism for the ODS process over HTS-1 is proposed.

Olefin-linked covalent organic framework nanotubes based on triazine for selective oxidation of sulfides with O2 powered by blue light

Imine, hydrazone, and olefin-linked covalent organic frameworks (COFs) prosper in visible light photocatalysis. Markedly, the olefin-linked COFs are usually superior in transfer of π-conjugated electron powered by visible light albeit their construction is more challenging. Herein, two olefin-linked COFs were forged between 2,4,6-trimethyl-1,3,5-triazine (TMT) and 2,4,6-tris(4-formyl-phenyl)-1,3,5-triazine (TFPT) or 1,3,5-tris(4-formyl-phenyl)-benzene (TFPB) to afford TTO-COF or TBO-COF, respectively. Both of the olefin-linked COFs based on triazine are of good crystallinity, uniform micropores, and high specific surface areas, but of different morphologies, namely nanotubes and nanosheets. Compared to TBO-COF, TTO-COF nanotubes were constructed with two building blocks based on triazine, which could not only improve the planarity of a single layer but also cause closer stacking of layers in between. Therefore, TTO-COF nanotubes exhibit better photocatalytic performance and stability in the selective oxidation of organic sulfides into corresponding sulfoxides with O2 powered by blue light. Mechanistic investigation evidence the formation of desired sulfoxides was shaped by both electron and energy transfer pathways over TTO-COF nanotubes. This work underlines the ascendancy of olefin-linked COFs inasmuch as they provide an effective platform to construct efficient and durable photocatalysts based on adaptable organic building blocks.

Air Quality in Nigerian Urban Environments: A Comprehensive Assessment of Gaseous Pollutants and Particle Concentrations

The rise in gaseous pollutants and particulate concentrations is a serious problem for the environment. This study examined the air quality within four urban areas (Awka, Ekwulobia, Nnewi, and Onitsha) in Anambra State, Nigeria. The concentrations of known air pollutants including suspended particulate matter (PM2.5 and PM10), nitrogen dioxide (NO2), sulfur dioxide (SO2), methane (CH4), volatile organic compounds (VOCs), hydrogen sulfide (H2S), ammonia (NH3), ozone (O3), carbon dioxide (CO2) and carbon monoxide (CO) were assessed at various locations within the study areas using Aeroqual air quality monitoring devices, and the results were compared with the WHO air quality guidelines for health impact assessment. The air quality index (AQI) was interpolated from the pollutant concentrations in order to show hazard categories of air quality conditions over the study locations. The mean concentrations of SO2, CH4, and VOCs within the residential locations of Awka, Ekwulobia, and Nnewi were in the range of 200-8000 µg m-3 and exceeded WHO limits for air quality. While the levels of CO2, SO2, and CH4 (3.25-1,027,000 µg m-3) within the commercial locations of Awka, Ekwulobia, and Nnewi exceeded WHO limits, only VOCs (500-1100 µg m-3) within Awka and Ekwulobia exceeded the limits. The 62-181 µg m-3 and 40-295 µg m-3 ranges of PM2.5 and PM10, respectively within the Nnewi and Ekwulobia commercial locations were the only particle concentrations at which the World Health Organization (WHO) recommended limits for health aspects of air pollution were exceeded. The AQI calculations showed air quality within some of the locations may have potential risks for public health.

Adsorption and Separation of Ethyl Mercaptan from Methane by Hydroxyl Groups on the Surface of HTiNbO5-Nanosheets.

Adsorption and separation of light mercaptan (R-SH, R = C1-C4) from methane gas can effectively improve the utilization efficiency of methane and the resource conversion of organic sulfide. To further investigate the effects of composition and structural characteristics of laminates on desulfurization performance, in this paper, a two-dimensional (2D) HTiNbO5-nanosheet (HTiNbO5-NS) was constructed. In addition, the hydrogen-bonding interaction between the exposed hydroxyl active sites on the surface of HTiNbO5-NS and ethyl mercaptan (Et-SH) was constructed to realize the adsorption and separation of Et-SH from methane gas. The breakthrough adsorption capacity (Cap (BT)) of HTiNbO5-NS is 14.35 mg·g-1 in a micro fixed bed with a space velocity of 6000 h-1. The regeneration desulfurization rate (q) of the 10-cycle regeneration adsorption was ca. 96%. Furthermore, density functional theory (DFT) calculation results show that the S atoms of Et-SH and HTiNbO5-NS with the terminal hydroxyl and bridge hydroxyl have electron cloud covering to form the hydrogen-bonding interaction. In addition, the formation details of this hydrogen-bond interaction are discussed. The effects of Ti on the microstructure, hydroxyl acid, hydroxyl content, surface area, and pore volume of nanosheets were studied to explain the reasons for the differences in the properties of the two kinds of nanosheets. This work broadens the design of 2D niobium-based efficient adsorbents for R-SH based on hydrogen-bonding interaction and is helpful to enrich the application of the hydrogen-bonding interaction.

A novel free-standing metal organic frameworks-derived cobalt sulfide polyhedron array for shuttle effect suppressive lithium–sulfur batteries

Metal-organic-frameworks-derived nanostructures have received broad attention for secondary batteries. However, many strategies focus on the preparation of dispersive materials, which need complicated steps and some additives for making electrodes of batteries. Here, we develop a novel free-standing Co9S8 polyhedron array derived from ZIF-67, which grows on a three-dimensional carbon cloth for lithium–sulfur (Li–S) battery. The polar Co9S8 provides strong chemical binding to immobilize polysulfides, which enables efficiently suppressing of the shuttle effect. The free-standing S@Co9S8 polyhedron array-based cathode exhibits ultrahigh capacity of 1079 mAh g−1 after cycling 100 times at 0.1 C, and long cycling life of 500 cycles at 1 C, recoverable rate-performance and good temperature tolerance. Furthermore, the adsorption energies towards polysulfides are investigated by using density functional theory calculations, which display a strong binding with polysulfides.

Wastewater deodorization: problems and solutions

The problem of specific malodours odorants, emitted from the territory of wastewater and sludge treatment facilities is set in the article. This article presents a critical review concerning the reasons of odorants formation during wastewater treatment, their influence on human health and ways of wastewater and sludge deodorization. Review is presented by 52 resources of Russian, Chinese, Italian, Greek, Indian, American and other researches from 2000 to 2021 years. According to the review the main sources of odours emission are units of mechanical treatment, sludge thickening and sludge digestion. The main odorants are volatile organic compounds (VOCs), hydrogen sulphide, ammonia, particulate matters and greenhouse gases (carbon dioxide, methane, nitrogen oxide). Based on the article, there are two ways of emission controlling: controlling the technological parameters of wastewater treatment process or gases treatment at specific facilities (adsorbers, biofilters, bioscrubbers, chemical scrubbers).

Effect of Garlic Organic Sulfides on Gene Expression Profiling in HepG2 Cells and Its Biological Function Analysis by Ingenuity Pathway Analysis System and Bio-Plex-Based Assays

Garlic organic sulfides are dietary bioactive components with multiple biofunctions to prevent chronic diseases/inflammation and promote human health. DADS (diallyl disulfide), DATS (diallyl trisulfide), and DTS (diallyl tetrasulfide) are typical organic sulfides with similar structures from garlic. However, the structure-activity relationship of garlic organic sulfides remained unknown. The aim of the present study was to investigate the effect of DADS, DATS, and DTS on the gene expression profiling of human hepatocellular carcinoma cells (HepG2) by application of microarray and specialized analysis software, GO, Bio-Plex-based cytokines assay and IPA and analyze their structure-activity relationship according to antioxidant, anti-inflammatory, and metabolic-related properties. According to the microarray data, with the increase of S atom in garlic organic sulfides, its biological activity was gradually enhanced. In the general catalog of GO, garlic organic sulfides mainly affect biological process, molecular function, and cellular component. RT-qPCR results indicated that the microarray data is trustworthy, and the structure-activity analysis data found that more sulfur atoms have more powerful properties; thus, microarray data of DTS was preceded to the subsequent IPA analysis. The results of IPA analysis showed that the top 5 signaling pathways and molecular functions were disturbed by DTS; the molecular functions with the highest scores affected by DTS are cancer, cell apoptosis, and cell proliferation, which imply that the occurrence or metabolism of these diseases is related to the differential expression of the above-mentioned related genes and the activation of signaling channels, and the core of the most significant molecular network is inflammation. Finally, the results found that the secretions of 6 cytokines in macrophages were significantly inhibited by DTS treatment. This is the first study that analyzed the structure-activity relationship of garlic organic sulfides, which will provide useful genetic information for its multi-biofunction and promote their clinical application in the near future.

Characterization of aroma profiles and aroma-active compounds in high-salt and low-salt shrimp paste by molecular sensory science

Flavor characteristics of raw shrimp, high-salt and low-salt shrimp paste were evaluated and compared by sensory analysis, headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) and solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS). In addition, aroma profiles and aroma-active compounds in these three samples were analyzed by solvent-assisted flavor evaporation-gas chromatography-olfactometry-mass spectrometry (SAFE-GC-O-MS). Results of sensory evaluation revealed that these three samples showed significant differences in sensitivity to the W2W, W2S, W1S and W1W sensors of the electronic nose (p < 0.05), which represent organic sulfides, alkane aromatic compounds, short chain alkanes, and sulfides, respectively. Assessment of sensory parameters indicated tha high-salt shrimp paste had a strong roasted and meaty aroma, while low-salt shrimp paste showed an umami aroma more similar to raw shrimp. A total of 118 volatile compounds were identified using the three afore-mentioned gas chromatography methods. Among them, 37 aroma-active compounds were detected by GC-O. High-salt shrimp was shown to contain more acids, aldehydes and heterocyclic compounds, which resembled cheese, roasted and meaty aromas. In contrast, low-salt shrimp paste contained more esters, which was similar to the umami aroma profile of raw shrimp. Interestingly, pyrazines were only produced in fermented shrimp paste samples, suggesting that they were produced during the fermentation process and they may contribute unique roasted and meaty aromas, which were important for the overall aroma characteristics of shrimp paste.

Solvent-Free Visible Light Photocatalytic Oxidation Processes Mediated by Transparent Films of an Imine-Based Organic Polymer

Reaction between concentrated solutions of phenotiazine containing trialdehyde building block 4,4′,4″-(10-phenothiazine-3,7,10-triyl)tribenzaldehyde and (1R,2R)-cyclohexane-1,2-diamine results in the formation of a yellow transparent film. Exhaustive characterization of this material indicates that it is the result of the assembly of a linear polymer resulting from the linking of imine-based macrocycles. Phenotiazine units confer to this plastic the optical properties characteristic of photocatalytic materials. The transparency of the obtained material enabled the performance of solvent-free photocatalytic processes. This concept is illustrated by the oxidation of liquid organic sulfides, which can be performed in a recyclable manner. According to selective quenching experiments, such processes are the result of the energy transfer to oxygen molecule, generating singlet oxygen that is able to activate the sulfide molecules directly.

Bacterial epiphyte and endophyte communities of seagrass Thalassia hemprichii: the impact of feed extract solution.

The global seagrass bed ecosystem acts as a natural ecological barrier in the littoral coastal zone. In recent years, this ecosystem has suffered from serious eutrophication and destruction caused by the continuous expansion of aquaculture. However, our understanding of the influence of aquaculture on the bacterial community remains limited. In this study, we used 16S amplicon sequencing to evaluate the impact of aquaculture feed extract solution on the composition and function of bacterial epiphytes and endophyte communities of the core seagrass from the seagrass bed ecosystem in Hainan, Thalassia hemprichii. The feed extract solution was the main factor that significantly affected the bacterial epiphyte and endophyte community structure of seagrass leaves but had no marked effect on alpha diversity was observed. Additionally, the bacterial epiphyte and endophyte community of the T. hemprichii leaves alleviated the effects of organic matter, sulfide, and nutrients caused by aquaculture wastewater. The feed extract solution promoted the proliferation of Bacteroidales, Vibrio, Desulfobulbaceae, Desulfobacteraceae, Pseudoalteromonas, Paludibacter, Marinomonas, and Pseudomonas in the leaves and root of T. hemprichii, which can effectively improve the digestibility of eutrophication. In fact, Desulfobacteraceae and Desulfobulbaceae can reduce sulfate to sulfide and oxidize sulfide to sulfur within seagrass, indicating that the increase in Desulfobulbaceae and Desulfobacteraceae facilitated the accumulation of sulfide with the treatment of feed extract solution, which may be the reason for the degradation of seagrass caused by aquaculture wastewater containing high concentrations of organic pollutants. These results suggest that although seagrass beds can withstand low concentrations of aquaculture pollutants, sulfide emissions should be minimized.