The development of active and low-cost transition metal oxide-based catalysts was vital for the catalytic oxidation of toluene. This study aimed to prepare Fe-Mn oxide catalysts by Mn-rich limonite, and investigate the catalytic activity and mechanism for toluene oxidation. The natural Mn-rich limonite was thermally activated at different temperatures and these thermally activated samples exhibited different oxidation activities. YL-300, obtained through thermal treatment at 300°C, exhibited excellent catalytic activity, showing 90% toluene conversion at 239°C (1000 ppm toluene) and remarkable catalytic stability even in the presence of water vapor (5 vol.%). The amount of oxygen vacancies in the catalyst was regulated by tuning the thermal treatment temperatures. Optimal thermal treatment facilitated the increase of oxygen vacancies and enhanced the oxygen mobility and redox capacity of YL-300, contributing to the complete oxidation of toluene to H2O and CO2. The oxidation of toluene was greatly influenced by the adsorbed oxygen species. This study demonstrates the potential of Mn-rich limonite as a promising catalyst for toluene oxidation, thereby promoting the utilization of natural mineral materials in the field of environmental pollution control.

This study evaluated the impact of three distinct diets; perennial ryegrass (GRS), perennial ryegrass/white clover (CLV) and total mixed ration (TMR), on the sensory properties and volatile profile of whole milk powder (WMP). The samples were evaluated using a hedonic sensory acceptance test (n = 99 consumers) and by optimised descriptive profiling (ODP) using trained assessors (n = 33). Volatile profiling was achieved by gas chromatography mass spectrometry using three different extraction techniques; headspace solid phase micro-extraction, thermal desorption and high capacity sorptive extraction. Significant differences were evident in both sensory perception and the volatile profiles of the WMP based on the diet, with WMP from GRS and CLV more similar than WMP from TMR. Consumers scored WMP from CLV diets highest for overall acceptability, flavour and quality, and WMP from TMR diets highest for cooked flavour and aftertaste. ODP analysis found that WMP from TMR diets had greater caramelised flavour, sweet aroma and sweet taste, and that WMP from GRS diets had greater cooked aroma and cooked flavour, with WMP derived from CLV diets having greater scores for liking of colour and creamy aroma. Sixty four VOCs were identified, twenty six were found to vary significantly based on diet and seventeen of these were derived from fatty acids; lactones, alcohols, aldehydes, ketones and esters. The abundance of δ-decalactone and δ-dodecalactone was very high in WMP derived from CLV and GRS diets as was γ-dodecalactone derived from a TMR diet. These lactones appeared to influence sweet, creamy, and caramelised attributes in the resultant WMP samples. The differences in these VOC derived from lipids due to diet are probably further exacerbated by the thermal treatments used in WMP manufacture.

Due to the coronavirus disease 2019 (COVID-19) pandemic, there is currently a need for accurate, rapid, and easy-to-administer diagnostic tools to help communities manage local outbreaks and assess the spread of disease. The use of artificial intelligence within the domain of breath analysis techniques has shown to have potential in diagnosing a variety of diseases, such as cancer and lung disease, by analyzing volatile organic compounds (VOCs) in exhaled breath. This combined with their rapid, easy-to-use, and noninvasive nature makes them a good candidate for use in diagnosing COVID-19 in large scale public health operations. However, there remains issues with their implementation when it comes to the infrastructure currently available to support their use on a broad scale. This includes issues of standardization, and whether or not a characteristic VOC pattern can be identified for COVID-19. Despite these difficulties, breathalyzers offer potential to assist in pandemic responses and their use should be investigated.

Diet has a major influence on the composition and metabolic output of the gut microbiome. Higher-protein diets are often recommended for older consumers; however, the effect of high-protein diets on the gut microbiota and faecal volatile organic compounds (VOC) of elderly participants is unknown. The purpose of the study was to establish if the faecal microbiota composition and VOC in older men are different after a diet containing the recommended dietary intake (RDA) of protein compared with a diet containing twice the RDA (2RDA). Healthy males (74⋅2 (sd 3⋅6) years; n 28) were randomised to consume the RDA of protein (0⋅8 g protein/kg body weight per d) or 2RDA, for 10 weeks. Dietary protein was provided via whole foods rather than supplementation or fortification. The diets were matched for dietary fibre from fruit and vegetables. Faecal samples were collected pre- and post-intervention for microbiota profiling by 16S ribosomal RNA amplicon sequencing and VOC analysis by head space/solid-phase microextraction/GC-MS. After correcting for multiple comparisons, no significant differences in the abundance of faecal microbiota or VOC associated with protein fermentation were evident between the RDA and 2RDA diets. Therefore, in the present study, a twofold difference in dietary protein intake did not alter gut microbiota or VOC indicative of altered protein fermentation.

Volatile organic compounds (VOCs) released by plants are generally involved in host recognition and host selection for many phytophagous insects. However, for leafhoppers and planthoppers, host recognition is mainly thought to involve a phototactic response, but it is not clear if a host plant could be selected based on the volatile cues it emits. In this study we evaluated olfactory responses in dual choice tests of two Hemiptera species, Dalbulus maidis (De Long) (Cicadellidae) and Peregrinus maidis (Ashmead) (Delphacidae), vectors of maize-stunting diseases, to three maize (Zea mays L.) germplasms, a temperate and a tropical hybrid and a landrace. VOCs emitted by the germplasms were collected and identified using gas chromatography-mass spectrometry. The temperate hybrid released significantly more VOCs than the tropical hybrid and the landrace, and its volatile profile was dominated by (±)-linalool. D. maidis preferred odours emitted from the temperate hybrid, whereas P. maidis preferred odours from the tropical hybrid and the landrace over the temperate one. In order to test if linalool plays a role in the behavioural responses, we assayed this compound in combination with the tropical hybrid, to provide other contextual olfactory cues. D. maidis was attracted to the tropical hybrid plus a 0.0001% linalool solution, indicating that this compound could be part of a blend of attractants. Whereas addition of linalool resulted in a slight, though not significant, reduction in host VOC attractiveness for P. maidis. Both hopper species responded to olfactory cues in the absence of supplementary visual cues.

The percolation of water through waste landfills produces leachates with high concentrations of which can generate -exchanged clays within geochemical barriers. These leachates also contain several volatile organic compounds (VOCs) which can interact with the clay barrier. The aim of the present study was to characterize the sorption of eight short-chain VOCs (acetonitrile, methyl tert-butyl ether, dichloromethane, benzene, phenol, ethanol, acetone and aniline) on -smectite, and to identify their sorption mechanisms. The samples treated were characterized by carbon and nitrogen elemental analysis, infrared spectroscopy, powder X-ray diffraction, and thermogravimetric analysis. For acetonitrile, methyl tert-butyl ether, dichloromethane and benzene, no sorption was detected. Phenol, ethanol and acetone were sorbed very weakly, through Van der Waals interactions. Aniline molecules were sorbed strongly on -smectite mainly with hydrogen bonds between aniline and interlayer water molecules. However, aniline sorption decreased the hydrophilic character of the -smectite, which may increase the permeability of the clay barrier.

The present research studied the effect of a dietary inclusion with Hermetia illucens larvae meal (Hi) on rainbow trout’s fillets chemical composition. The effect of Hi inclusion in diets on rainbow trout chemical characteristics was evaluated. Trout were fed three different diets: control (C, no Hi inclusion), 25% and 50% of substitution of fish meal with Hi (Hi25 and Hi50, respectively). Fillets were analysed to quantify proximate composition, carbohydrates percentage, colour parameters, nucleotides concentration, fatty acids profile, volatile organic compounds (VOCs) and myofibrillar and sarcoplasmic concentrations. Diets did not affect proximate composition. Contrariwise, Hi50 diet decreased fillet yellowness and both substitution percentages affected negatively adenosine monophosphate concentration. Saturated fatty acids, mostly C12 : 0, increased their contents in relation with Hi inclusion at the expense of monounsaturated and polyunsaturated (both n-3 and n-6) fatty acids. Less modifications were reported in VOCs as only heptanal and octanal concentrations were affected, no new compounds appeared in relation with Hi inclusion. No modifications in proteins patterns were shown even if myofibrillar content decreased in trout fed Hi50. The results highlighted that chemical modifications occurred in fillets were related to the chemical composition of the H. illucens meal and to the percentage of inclusion in the diet. Substitution of fish meal with a precisely percentage of H. illucens meal could be a potential future solution in order to decrease the quantity of fish meal used in aquafeeds.

This study was conducted to determine the effects of feeding olive cake and linseed to lambs on the volatile organic compounds (VOCs) in raw and cooked meat. Four groups of eight male Appenninica lambs each were fed: conventional cereal-based concentrates (diet C), concentrates containing 20% on a dry matter (DM) basis of rolled linseed (diet L), concentrates containing 35% DM of stoned olive cake (diet OC), or concentrates containing both rolled linseed (10% DM) and stoned olive cake (17% DM; diet OCL). The longissimus dorsi muscle of each lamb was sampled at slaughter and was subjected to VOC profiling through the use of SPME-GC-MS. In the raw meat, the concentration of 3-methylpentanoic acid was higher in treatment C as compared with treatments L, OC and OCL (P<0.01). Moreover the level of nonanoic acid was greater in treatments C and OC than in treatment L (P<0.05). With respect to alcohols, in raw meat the amount of 2-phenoxyethanol in treatment OCL was lower than in treatments C (P<0.01) and OC (P<0.05), while in cooked meat the amount of 1-pentanol was higher in treatment C than in treatment OC (P<0.05). Apart from these compounds, none of the lipid oxidation-derived volatiles was significantly affected by the dietary treatment. Therefore, the results suggest that the replacement of cereal concentrates with linseed and/or olive cake did not cause appreciable changes in the production of volatile organic compounds in lamb meat.

Breath analysis is becoming increasingly established as a means of assessing metabolic, biochemical and physiological function in health and disease. The methods available for these analyses exploit a variety of complex physicochemical principles, but are becoming more easily utilised in the clinical setting. Whilst some of the factors accounting for the biological variation in breath metabolite concentrations have been clarified, there has been relatively little work on the dietary factors that may influence them. In applying breath analysis to the clinical setting, it will be important to consider how these factors may affect the interpretation of endogenous breath composition. Diet may have complex effects on the generation of breath compounds. These effects may either be due to a direct impact on metabolism, or because they alter the gastrointestinal flora. Bacteria are a major source of compounds in breath, and their generation of H2, hydrogen cyanide, aldehydes and alkanes may be an indicator of the health of their host.