Methanethiol Research Articles

Characteristics of extra-oral halitosis induced by functional constipation: a prospective cohort study

Characteristics of extra-oral halitosis induced by functional constipation (FC) have never been revealed. To address this, this prospective cohort was conducted with 100 FC patients, who were divided into a halitosis group and a negative group. Organoleptic score (OLS) ⩾ 2 in nose breath was diagnosed as extra-oral halitosis. Concentration of overall volatile sulfur compounds (VSCs) measured by Halimeter, concentration of hydrogen sulfide (HS), methanethiol (MT), dimethyl sulfide (DMS) and their total amount measured by OralChroma in nose breath was recorded as C-VSC, C-HS, C-MT, C-DMS and C-sum respectively. We found that 82% (82/100) of the FC patients had extra-oral halitosis. However, only 12.5% (3/82) and 1.22% (1/82) of halitosis group were correctly diagnosed with the current diagnostic threshold of C-VSC ⩾ 110 parts per billion (ppb) and ⩾150 ppb. C-VSC, C-DMS and C-sum were significantly higher in the halitosis group compared to the negative group (all P < 0.001), with ratios of about 2.2 times, 3.1 times and 2.1 times respectively. C-HS and C-MT were low and not significantly different between the groups. Positive correlations were observed among OLS, C-VSC, C-DMS and C-sum. The area under curve of receiver operating characteristics of C-VSC, C-DMS and C-sum for predicting FC-induced halitosis was 0.909, 0.9073 and 0.962 respectively, with the threshold values of ⩾36 ppb, ⩾52 ppb and ⩾75 ppb respectively. Therefore, we conclude that: (1) DMS is the primary contributor to FC-induced extra-oral halitosis. (2) OLS, Halimeter and OralChroma are consistent in detecting FC-induced extra-oral halitosis. (3) The diagnostic threshold for Halimeter should be adjusted to C-VSC ⩾ 36 ppb and the diagnostic threshold for OralChroma should be set as C-DMS ⩾ 52 ppb for diagnosing FC-induced extra-oral halitosis.

Interspecies metabolite transfer fuels the methionine metabolism of Fusobacterium nucleatum to stimulate volatile methyl mercaptan production.

The major oral odor compound methyl mercaptan (CH3SH) is strongly associated with halitosis and periodontitis. CH3SH production stems from the metabolism of polymicrobial communities in periodontal pockets and on the tongue dorsum. However, understanding of CH3SH-producing oral bacteria and their interactions is limited. This study aimed to investigate CH3SH production by major oral bacteria and the impact of interspecies interactions on its generation. Using a newly constructed large-volume anaerobic noncontact coculture system, Fusobacterium nucleatum was found to be a potent producer of CH3SH, with that production stimulated by metabolic interactions with Streptococcus gordonii, an early dental plaque colonizer. Furthermore, analysis of extracellular amino acids using an S. gordonii arginine-ornithine antiporter (ArcD) mutant demonstrated that ornithine excreted from S. gordonii is a key contributor to increased CH3SH production by F. nucleatum. Further study with 13C, 15N-methionine, as well as gene expression analysis, revealed that ornithine secreted by S. gordonii increased the demand for methionine through accelerated polyamine synthesis by F. nucleatum, leading to elevated methionine pathway activity and CH3SH production. Collectively, these findings suggest that interaction between S. gordonii and F. nucleatum plays a key role in CH3SH production, providing a new insight into the mechanism of CH3SH generation in oral microbial communities. A better understanding of the underlying interactions among oral bacteria involved in CH3SH generation can lead to the development of more appropriate prophylactic approaches to treat halitosis and periodontitis. An intervention approach like selectively disrupting this interspecies network could also offer a powerful therapeutic strategy.IMPORTANCEHalitosis can have a significant impact on the social life of affected individuals. Among oral odor compounds, CH3SH has a low olfactory threshold and halitosis is a result of its production. Recently, there has been a growing interest in the collective properties of oral polymicrobial communities, regarded as important for the development of oral diseases, which are shaped by physical and metabolic interactions among community participants. However, it has yet to be investigated whether interspecies interactions have an impact on the production of volatile compounds, leading to the development of halitosis. The present findings provide mechanistic insights indicating that ornithine, a metabolite excreted by Streptococcus gordonii, promotes polyamine synthesis by Fusobacterium nucleatum, resulting in a compensatory increase in demand for methionine, which results in elevated methionine pathway activity and CH3SH production. Elucidation of the mechanisms related to CH3SH production is expected to lead to the development of new strategies for managing halitosis.

The assessment of halitosis with a new screening tool in medication-related osteonecrosis of the jaw.

This study aimed to identify the levels of halitosis in patients with Medication-related osteonecrosis of the jaw (MRONJ) and osteoporosis and to suggest a new MRONJ screening method using halitosis measurement. From October 2019 to April 2023, participants aged 19years or older without periodontal disease were selected. Seventy-five participants, 25 in each group, were divided into an MRONJ group, an osteoporosis group without MRONJ, and a control group without osteoporosis and not taking osteoporosis drugs or antibiotics. Each participant underwent halitosis assessment twice using an exhaled breath analyzer to measure halitosis twice by blowing a straw for 1min. Measured concentrations of hydrogen, hydrogen sulfide, and methyl mercaptan were compared between groups. Data from 22 patients in the MRONJ group, 25 in the osteoporosis group, and 25 in the control group were analyzed. The concentrations of hydrogen sulfide and methyl mercaptan were significantly higher in the MRONJ group than in the other groups, but the concentrations of hydrogen did not differ between the groups. When comparing the concentrations of hydrogen sulfide and methyl mercaptan in osteoporosis patients and solid cancer patients in the MRONJ group, there was a significant difference in hydrogen sulfide concentration, but there was no significant difference in methyl mercaptan. Quantifying the level of halitosis can be used to screen for MRONJ in patients taking bisphosphonates, such as patients with osteoporosis, prostate cancer, and breast cancer. MRONJ is accompanied by bad breath, and the concentrations of hydrogen sulfide and methyl mercaptan are associated with MRONJ.

Copper-decorated strategy based on defect-rich NH2-MIL-125(Ti) boosts efficient photocatalytic degradation of methyl mercaptan under sunlight

Photocatalysis has received significant attention as a technology that can solve environmental problems. Metal-organic frameworks are currently being used as novel photocatalysts but are still limited by the rapid recombination of photogenerated carriers, low photogenerated electron migration efficiency and poor solar light utilization rate. In this work, a novel photocatalyst was successfully constructed by introducing Cu species into thermal activated mixed-ligand NH2-MIL-125 (Ti) via defect engineering strategy. The constructed defect structure not only provided 3D-interconnected gas transfer channels, but also offered suitable space to accommodate introduced Cu species. For the most effective photocatalyst 0.2Cu/80%NH2-MIL-125 (300 °C) with optimized Cu content, the photocatalytic degradation rate of CH3SH achieved 4.65 times higher than that of pristine NH2-MIL-125 under visible light (λ > 420 nm). At the same time, it showed great degradation efficiency under natural sunlight, 100 ppm CH3SH was completely removed within 25 min in full solar light illumination. The improved catalytic efficiency is mainly due to the synergistic effect of the integrated Schottky junction and rich-defective NH2-MIL-125, which improved the bandgap and band position, and thus facilitated the separation and transfer of the photo-generated carriers. This work provided a facile way to integrate Schottky junctions and rich-defective MOFs with high stability. Due to its excellent degradation performance under sunlight, it also offered a prospective strategy for rational design of high-efficiency catalysts applied in environmental technologies.

Effects of operating conditions on the in situ control of sulfur-containing odors by using a novel alternative landfill cover and its transformation mechanism.

Sulfur-containing gases are main sources of landfill odors, which has become a big issue for pollution to environment and human health. Biocover is promising for treating landfill odors, with advantages of durability and environmental friendliness. In this study, charcoal sludge compost was utilized as the main effective component of a novel alternative landfill cover and the in situ control of sulfur-containing odors from municipal solid waste landfilling process was simulated under nine different operating conditions. Results showed that five sulfur-containing odors (hydrogen sulfide, H2S; methyl mercaptan, CH3SH; dimethyl sulfide, CH3SCH3; ethylmercaptan, CH3CH2SH; carbon disulfide, CS2) were monitored and removed by the biocover, with the highest removal efficiencies of 77.18% for H2S, 87.36% for CH3SH, and 92.19% for CH3SCH3 in reactor 8#, and 95.94% for CH3CH2SH and 94.44% for CS2 in reactor 3#. The orthogonal experiment showed that the factors influencing the removal efficiencies of sulfur-containing odors were ranked from high to low as follows: temperature > weight ratio > humidity content. The combination of parameters of 20% weight ratio, 25°C temperature, and 30% water content was more recommended based on the consideration of the removal efficiencies and economic benefits. The mechanisms of sulfur conversion inside biocover were analyzed. Most organic sulfur was firstly degraded to reduced sulfides or element sulfur, and then oxidized to sulfate which could be stable in the layer as the final state. In this process, sulfur-oxidizing bacteria play a great role, and the distribution of them in reactor 1#, 5#, and 8# was specifically monitored. Bradyrhizobiaceae and Rhodospirillaceae were the dominant species which can utilize sulfide as substance to produce sulfate and element sulfur, respectively. Based on the results of OUTs, the biodiversity of these sulfur-oxidizing bacteria, these microorganisms, was demonstrated to be affected by the different parameters. These results indicate that the novel alternative landfill cover modified with bamboo charcoal compost is effective in removing sulfur odors from landfills. Meanwhile, the findings have direct implications for addressing landfill odor problems through parameter adjustment.

Qualitative and quantitative rapid detection of VOCs differentially released by VAP-associated bacteria using PTR-MS and FGC-PTR-MS.

Ventilator-associated pneumonia (VAP) is a prevalent disease caused by microbial infection, resulting in significant morbidity and mortality within the intensive care unit (ICU). The rapid and accurate identification of pathogenic bacteria causing VAP can assist clinicians in formulating timely treatment plans. In this study, we attempted to differentiate bacterial species in VAP by utilizing the volatile organic compounds (VOCs) released by pathogens. We cultured 6 common bacteria in VAP in vitro, including Acinetobacter baumannii, Enterobacter cloacae, Escherichia coli, Pseudomonas aeruginosa, Stenotrophomonas maltophilia, and Staphylococcus aureus, which covered most cases of VAP infection in clinic. After the VOCs released by bacteria were collected in sampling bags, they were quantitatively detected by a proton transfer reaction-mass spectrometry (PTR-MS), and the characteristic ions were qualitatively analyzed through a fast gas chromatography-proton transfer reaction-mass spectrometry (FGC-PTR-MS). After conducting principal component analysis (PCA) and analysis of similarities (ANOSIM), we discovered that the VOCs released by 6 bacteria exhibited differentiation following 3 h of quantitative cultivation in vitro. Additionally, we further investigated the variations in the types and concentrations of bacterial VOCs. The results showed that by utilizing the differences in types of VOCs, 6 bacteria could be classified into 5 sets, except for A. baumannii and E. cloacae which were indistinguishable. Furthermore, we observed significant variations in the concentration ratio of acetaldehyde and methyl mercaptan released by A. baumannii and E. cloacae. In conclusion, the VOCs released by bacteria could effectively differentiate the 6 pathogens commonly associated with VAP, which was expected to assist doctors in formulating treatment plans in time and improve the survival rate of patients.

Catalytic hydrolysis of methyl mercaptan and methyl thioether on hydroxyl-modified ZrO2: a density functional theory study.

The purification and removal of organic sulfur from natural gas is conducive to increasing the added value of natural gas and reducing environmental pollution. In this study, the adsorption properties of methyl mercaptan (CH3SH), dimethyl sulfide (C2H6S) and H2O on the surface of hydroxyl-modified ZrO2 were investigated using density functional theory (DFT) calculations. Additionally, a reaction mechanism was proposed for hydroxyl-modified ZrO2 catalyzing the hydrolysis of CH3SH and C2H6S. The chemisorption of H2O molecules on the catalyst surface is attributed to H-O and H-Zr bonds. The chemisorption of CH3SH and C2H6S on the catalyst surface is attributed to Zr-S bonds. Competitive adsorption between the three gases exists only between CH3SH and C2H6S. It reveals the water-resistant properties of hydroxyl-modified ZrO2 in desulfurization. The adsorption energies of the three gas molecules on the hydroxyl-modified ZrO2 surface are in the order of CH3SH - (Zr) > C2H6S - (Zr) > H2O - (OH). The natural hydrolysis of CH3SH and C2H6S is a heat-absorbing process that cannot occur spontaneously. The rate-determining step for CH3SH catalytic hydrolysis is the formation of CH3O. The fracture of CH3SHO is the rate-determining step for C2H6S catalytic hydrolysis. The depletion of the surface hydroxyl groups can be replenished by the dissociation of H2O molecules. Hydroxyl-modified ZrO2 facilitated the hydrolysis process of CH3SH to a greater extent than that of C2H6S. This study provides theoretical guidance for industrial applications and the design of hydroxyl-containing hydrolysis catalysts.

Adsorption and dissociation of CH3SH on FeS surface: A DFT study

Methyl mercaptan (CH3SH) is a common sulfide in oil and natural gas, easily corroded in transportation pipes and storage containers. In this paper, the adsorption and dissociation processes of CH3SH on FeS (0 0 1), (0 1 1), (1 0 0) and (1 1 1) surfaces have been studied by the density functional theory (DFT). And the characteristics of the adsorption and dissociation processes were elucidated. The calculated surface energies show that the order of surface stability is (0 0 1) > (0 1 1) > (1 0 0) > (1 1 1). The stability of CH3SH adsorption is (1 1 1) > (1 0 0) > (0 1 1) > (0 0 1) by the adsorption energy, and the most stable adsorption configurations are obtained. Compared with the changes in electron density and the partial density of states (PDOS) before and after adsorption, there is an obvious electron orbital hybrid phenomenon between CH3SH and FeS (1 0 0), (1 1 1) surface, and its adsorption is stronger than that of the other two surfaces. It can be seen from the calculation of the transition state that the dissociation reaction of CH3SH is endothermic on the (0 0 1) and (0 1 1) surfaces, while the exothermic reaction on the (0 1 1) and (0 0 1) surfaces. CH3SH will dissociate preferentially on the FeS (1 0 0) surface because the reaction of Ea and ΔE on this surface is the smallest. Overall, the adsorption and dissociation processes are exothermic, the increase in temperature makes the crystal surface unstable and susceptible to spontaneous combustion, and the phenomenon occurs first on the FeS (1 0 0) and FeS (1 1 1) surfaces. These findings increase the understanding of the electronic structure and energy of the sulfides' action on the FeS surface and also have a reference value for flame retardant research.

Defective UiO-66 by metal doping for highly efficient photocatalytic degradation of methyl mercaptan

Defective UiO-66 by metal doping exhibits considerable promise in the photocatalytic degradation of environmental contaminants, albeit how different metal doping affect formation of defects and its efficacy in the degradation of methyl mercaptan has yet to be comprehensively explored. In this study, a one-step solvothermal method was employed to successfully synthesize six distinct metal-doped UiO-66 with variations of defects by incorporating Ce, Al, Cu, Cr, Mg, and Fe. A systematic examination of the structural and photochemical attributes of these metal-doped UiO-66 materials was conducted through a series of characterisations. Metal doping creates defects in UiO-66, changes its colour and morphology and increases its specific surface area. Subsequently, the adsorption and photocatalytic degradation characteristics of these nanomaterials concerning methyl mercaptan were investigated. In comparison to pristine UiO-66, all metal-doped UiO-66 variants exhibited enhanced adsorption and photocatalytic degradation capabilities towards methyl mercaptan. Notably, among the prepared materials, FeUiO-66 demonstrated the most exceptional photocatalytic degradation performance, followed by CuUiO-66, AlUiO-66, CeUiO-66, CrUiO-66, and MgUiO-66 in that order. 1.0FeUiO-66 exhibiting the most remarkable performance, achieving a 99 % degradation of methyl mercaptan within 30 min. This represented a degradation rate 36.8 times higher than that of pure UiO-66, attributable to the incorporation of low-valence metals into the UiO-66 framework, resulting in the creation of oxygen vacancy defects. Furthermore, the presence of these metals facilitated electron transport, thereby enhancing the efficiency of photocatalytic degradation. This study underscores the potential of various metals-doped UiO-66 for adsorption and photocatalytic elimination of methyl mercaptan.

An evaluation of the effects of dietary mixed-species direct-fed microbial (probiotic) on growth performance, gas emissions, meat quality, nutrient digestibility, and fecal score in finishing pigs

This study examined the effects of mixed-species direct-fed microbial (DFM) on growth performance, gas emissions, meat quality, nutrient digestibility, and the fecal score of finishing pigs. A total of 100 crossbred finishing pigs ((Yorkshire × Landrace) × Duroc) weighing 58.97 ± 3.12 kg were randomly assigned to one of two diets (5 pigs per pen (2 barrows and 3 gilts); 50 pigs per treatment) in an 8-week trial. Dietary treatments comprised of the basal diet without probiotics control or basal diet + (0.1%) mixed probiotics (DFM). Mixed DFM supplementation showed a tendency to increase ( P = 0.093) the body weight of finishing pigs during day 56. Comparing mixed DFM with the control diet, mixed probiotics significantly improved average daily gain (ADG) during weeks 5–8 ( P = 0.024) and overall ( P = 0.013). DFM-supplemented diets reduced the emission of CH4 and NH3 significantly at weeks 4 and 8 compared with control. DFM supplementation did not affect H2S, methyl mercaptans, acetic acid, or CO2 emissions. Mixed DFM supplementation showed a tendency to increase ( P = 0.07) nitrogen digestibility. Pigs receiving mixed DFM had improved ADG and reduced NH3 and CH4 emissions without affecting meat quality, nutrient digestibility, intestinal microbes, and fecal score.

Catalytic ozonation mechanism over M1-N3C1 active sites

The structure-activity relationship in catalytic ozonation remains unclear, hindering the understanding of activity origins. Here, we report activity trends in catalytic ozonation using a series of single-atom catalysts with well-defined M1-N3C1 (M: manganese, ferrum, cobalt, and nickel) active sites. The M1-N3C1 units induce locally polarized M − C bonds to capture ozone molecules onto M atoms and serve as electron shuttles for catalytic ozonation, exhibiting excellent catalytic activities (at least 527 times higher than commercial manganese dioxide). The combined in situ characterization and theoretical calculations reveal single metal atom-dependent catalytic activity, with surface atomic oxygen reactivity identified as a descriptor for the structure-activity relationship in catalytic ozonation. Additionally, the dissociation barrier of surface peroxide species is proposed as a descriptor for the structure-activity relationship in ozone decomposition. These findings provide guidelines for designing high-performance catalytic ozonation catalysts and enhance the atomic-level mechanistic understanding of the integral control of ozone and methyl mercaptan.

Selection of consistent breath biomarkers of abnormal liver function using feature selection: a pilot study

PurposeBreath profiling has gained importance in recent years as it is a non-invasive technique to identify biomarkers for various diseases. Breath profiling of abnormal liver function in individuals for identifying potential biomarkers in exhaled breath could be a useful diagnostic tool. The objective of this study was to identify potential biomarkers in exhaled breath that remain stable and consistent during different physiological states, including rest and brief workouts, intending to develop a non-invasive diagnostic tool for detecting abnormal liver function.MethodOur study employed a gas chromatography and mass-spectrometer quantified dataset for analysis. Machine learning techniques, including feature selection and model training, were used to rank and evaluate potential biomarkers' contributions to the model's performance. Statistical methods were applied to filter significant and consistent biomarkers. The final selected biomarkers were iterated for all possible combinations using machine learning algorithms to determine their accuracy range. Furthermore, classification models were used to evaluate the performance metrics of the biomarkers and compare models.ResultThe final selected biomarkers, including 2-Myristynoyl Pantetheine, Pterin-6 Carboxylic Acid, Methyl Mercaptan, N-Acetyl Cysteine, and Butyric Acid, exhibited stable levels in exhaled breath during different physiological states. They showed high accuracy and precision in detecting abnormal liver function. Our machine learning models achieved an accuracy rate ranging from 0.7 to 0.95 in all conditions, with precision, recall, prediction probability, and a 95% confidence interval ranging from 0.84 to 0.94, using various combinations of these biomarkers.ConclusionOur statistical and machine learning analysis identified significant and potential biomarkers that contribute to the detection of abnormal liver function. These biomarkers were consistent across different physiological states of the body in both patient and healthy groups. The use of breath samples and feature selection machine learning methods proved to be an accurate and reliable approach for identifying these biomarkers. Our findings provide valuable insights for future research in this field and can inform the development of non-invasive and cost-effective diagnostic tests for liver disease.

Experimental Study on the Adsorption of Sulfide on Stainless Steel Surface

This work characterized the microstructure of stainless steel before and after adsorption. At the same time, the adsorption experiments at different temperatures and the adsorption characteristic experiment were carried out. The results show that chemical adsorption has taken place on the surface of stainless steel. The change of temperature has little effect on the functional groups of the stainless-steel surface after adsorption. Hydrogen sulfide showed the largest adsorption capacity and fastest rate, while methyl and ethyl mercaptan performed second. Carbonyl sulfide exhibited the smallest adsorption capacity and slowest rate.

Sulfate reduction behavior in response to changing of pressure coupling with temperature inside landfill

The behavior of sulfate reduction, which was the source of hydrogen sulfide (H2S) odor, was investigated under changing pressure and temperature conditions inside landfills. The results showed that the release of H2S and methyl mercaptan (MM) was significantly inhibited at 25 °C and 50 °C under pressure, and the highest H2S and MM concentrations released were only 0.82 %-1.30 % and 1.87 %-4.32 % of atmospheric pressure, respectively. Analysis of the microbial community structure and identification of sulfate-reducing bacteria (SRB) revealed that temperature significantly altered the microbial community in the landfill environment, while pressure inhibited some bacteria and induced the growth and reproduction of specific bacteria. Key SRB (Desulfosporosinus-ASV212, Desulfitibacter-ASV1744) mediated differentiated sulfate reduction behavior in the pressure-bearing environment at 25 °C, while key SRB (Dethiobacter-ASV177, Desulfitibacter-ASV2355 and ASV316) were involved at 50 °C. This study provides a theoretical basis for the formulation of landfill gas management and control strategies.

The Feasibility of Detecting Biosignatures in the TRAPPIST-1 Planetary System with JWST

The James Webb Space Telescope (JWST) provides the first opportunity to detect gases in the atmospheres of M-dwarf terrestrial planets and search for signs of life. Here we determine the detectability of a comprehensive suite of biosignature gases that may have been episodically prevalent across Earth’s history. We used coupled 1D climate–photochemical models to generate synthetic inhabited terrestrial planetary environments for TRAPPIST-1 d and e. These encompass cloudy and/or hazy Archean-Earth-like environments with either a dominant sulfur- or methane-producing biosphere, as well as clear and cloudy modern-Earth-like environments with photosynthetic oxygen-producing biospheres. We generate transmission spectra and assess the likely detectability of different biosignatures with JWST. Our simulations suggest that biogenically generated O2 and its photosynthetic by-product O3 will likely be extremely difficult to detect. We explored the detectability of methyl chloride (CH3Cl) as an alternative indicator for a photosynthetic biosphere but find that it will likely require significantly higher global surface fluxes than Earth’s. We find that the CH4 and CO2 disequilibrium pair is potentially detectable in ∼10 transits for both the methanogen-dominated Archean-like environment and the modern photosynthetic-dominated biosphere—even in cloudy atmospheres. Organic haze and methyl mercaptan are other potential biosignatures for the Archean. Given the likely difficulties in observing an oxygenic-photosynthetic biosphere with JWST, we conclude that the methanogenic biosphere revealed by the combination of outgassed CO2 in the presence of methanogenically generated CH4 may be the most persistent detectable biosignature for an Earth-like planet.

Influence of Carbonization Conditions on Structural and Surface Properties of K-Doped Mo2C Catalysts for the Synthesis of Methyl Mercaptan from CO/H2/H2S.

The cooperative transition of sulfur-containing pollutants of H2S/CO/H2 to the high-value chemical methyl mercaptan (CH3SH) is catalyzed by Mo-based catalysts and has good application prospects. Herein, a series of Al2O3-supported molybdenum carbide catalysts with K doping (denoted herein as K-Mo2C/Al2O3) are fabricated by the impregnation method, with the carbonization process occurring under different atmospheres and different temperatures between 400 and 600 °C. The CH4-K-Mo2C/Al2O3 catalyst carbonized by CH4/H2 at 500 °C displays unprecedented performance in the synthesis of CH3SH from CO/H2S/H2, with 66.1% selectivity and a 0.2990 g·gcat-1·h-1 formation rate of CH3SH at 325 °C. H2 temperature-programmed reduction, temperature-programmed desorption, X-ray diffraction and Raman and BET analyses reveal that the CH4-K-Mo2C/Al2O3 catalyst contains more Mo coordinatively unsaturated surface sites that are responsible for promoting the adsorption of reactants and the desorption of intermediate products, thereby improving the selectivity towards and production of CH3SH. This study systematically investigates the effects of catalyst carbonization and passivation conditions on catalyst activity, conclusively demonstrating that Mo2C-based catalyst systems can be highly selective for producing CH3SH from CO/H2S/H2.

Exploring the link between sulphur-containing compounds and noxious odours at waste management facilities: implications for odour monitoring and mitigation strategies.

With this study we challenge the widely held assumption that sulphur-containing compounds in ambient air are good indicators of the presence noxious odours near waste management facilities. We analysed an extensive set of olfactometric data and data on the concentrations of hydrogen sulphide and trace sulphur compounds (TSCs) near a waste management facility in Croatia in 2021. The results show that the presence of noxious odours significantly correlates only with the concentrations of hydrogen sulphide and methyl mercaptan in ambient air but not with other measured TSCs. Thus, in addition to the measurement of pollutants in ambient air, Integrated Pollution and Prevention Control (IPPC) permits should mandate olfactometric measurements to detect and mitigate noxious odours near waste management facilities.

Effects of Cooking Processes on Protein Nutritional Values and Volatile Flavor Substances of Silver Carp (Hypophthalmichthys molitrix).

Silver carp (Hypophthalmichthys molitrix) is normally cooked at a high temperature. In order to explore the effects of cooking methods on the protein nutritional values and volatile flavor substances of silver carp meat, the meat was fried, roasted and steamed, and its contents were determined in relation to moisture, protein, fat, ash, amino acids and volatile flavor substances. The results show that the moisture content of cooked silver carp can be ranked as follows: raw > steamed > roasted > fried. The protein content order of the four samples can be ranked: fried > roasted > raw > steamed. The ash and the fat contents of the four samples showed similar significant (p < 0.05) differences, in the order of fried > roasted > steamed > raw. The contents of all the amino acids in the fried meat were significantly (p < 0.05) higher than the contents in others, and the frying, roasting and steaming processes improved the umami taste (supported by the increased content of glutamate and aspartate) and the protein nutritional value (supported by the amino acid score, essential amino acid index and protein efficiency ratio) of the silver carp meat. A total of 51 compounds were detected in the fried, roasted and steamed meat. Frying and roasting reduced the fishy flavor of this meat. The odor activity value (OAV) indicated that methanethiol, 1-octen-3-ol and 2-heptanone were the key flavor chemicals in raw meat. Hexanal, propionaldehyde, octanal, nonanal, decanal, 1-octen-3-ol and 2-heptanone were key to the flavor of fried meat. Pentanal, decanal, methyl mercap-tan and 1-octen-3-ol contributed greatly to the overall flavor of the roasted meat. Nonanal, methylmercaptan and 1-octene-3-ol had strong effects on the flavor of the steamed silver carp meat.

Modulating the photooxidation selectivity on graphitic carbon nitride by tuning edge functional groups

Selective photooxidation reactions offer a promising route for transformation of organic pollutants into high-value products under mild conditions. In this work, we demonstrate that the edge functional groups in polymer carbon nitride (PCN) were key to the selectivity of methyl mercaptan (CH3SH) photocatalytic oxidation. The amino-decorated PCN favors the oxidation of the -SH group of CH3SH to forming CH3SO3H with selectivity up to 84.0%, while cyanamide-enriched PCN prefers to breaking the -CH3 end of CH3SH and produce H2SO4 with selectivity of 82.0%. The totally difference in reaction sites is ascribed to the functional-group-modulated electronic structure of PCN, which determines activity of photoinduced carriers and the molecular oxygen activation pathway. The amino- and cyanamide-decorated PCN leads to preferential generation of 1O2 and·O2-, respectively. This study highlights the significant role of edge groups engineering in modulation of the excitonic effects in PCN and the resultant selectivity control during photocatalytic reaction.

Enhancement of protective vaccine-induced antibody titer to swine diseases and growth performance by Amino-Zn, yucca extract, and β-mannanase feed additive in wean-finishing pigs.

The primary purpose of this research is to determine the effect of Amino-Zn (AZn), Yucca schidigera extract (YE), and β-mannanase enzyme supplementation on growth performance, nutrient digestibility, fecal gas emission, and immune response in pigs. A total of 180 crossbred pigs (6.57 ± 1 kg) were randomly assigned to one of three dietary treatments: CON-corn soybean meal (basal diet); TRT1-CON +1,000 ppm AZn + 0.07% yucca extract (YE) + 0.05% β-mannanase; and TRT2-CON +2,000 ppm AZn + 0.07% YE+ 0.05% β-mannanase for 22 weeks. Each treatment had 12 replicates with 5 pigs per pen. Pigs fed a diet supplemented with AZn, YE, and β-mannanase linearly increased (p < 0.05) BW and average daily gain at weeks 6, 12, 17, and 18. In contrast, the gain-to-feed ratio showed a linear increase (p < 0.05) from weeks 6 to 17 and the overall trial period. Moreover, the inclusion of experimental diets linearly decreased (p > 0.05) noxious gas emissions such as ammonia, hydrogen sulfide, acetic acid, carbon dioxide, and methyl mercaptans. The dietary inclusion of AZn, YE, and β-mannanase significantly increased the serological immune responses to Mycoplasma hyopneumoniae (MH) and foot-and-mouth disease virus (FMDV-O type) at the end of week 6 and porcine circovirus-2 (PCV-2) at week 19. Based on this result, we infer that the combination of AZn, YE, and β-mannanase supplement would serve as a novel in-feed additive to enhance growth performance and act as a boosting agent and immune stimulatory to increase the efficacy of swine vaccinations.