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Titanium dioxide nanobelts were prepared via the alkali-hydrothermal method for application in chemical gas sensing. The formation process of TiO[sub.2]-(B) nanobelts and their sensing properties were investigated in detail. FE-SEM was used to study the surface of the obtained structures. The TEM and XRD analyses show that the prepared TiO[sub.2] nanobelts are in the monoclinic phase. Furthermore, TEM shows the formation of porous-like morphology due to crystal defects in the TiO[sub.2]-(B) nanobelts. The gas-sensing performance of the structure toward various concentrations of hydrogen, ethanol, acetone, nitrogen dioxide, and methane gases was studied at a temperature range between 100 and 500 °C. The fabricated sensor shows a high response toward acetone at a relatively low working temperature (150 °C), which is important for the development of low-power-consumption functional devices. Moreover, the obtained results indicate that monoclinic TiO[sub.2]-B is a promising material for applications in chemo-resistive gas detectors.

Genome-wide association analyses using high-throughput metabolomics platforms have led to novel insights into the biology of human metabolism 1 – 7 . This detailed knowledge of the genetic determinants of systemic metabolism has been pivotal for uncovering how genetic pathways influence biological mechanisms and complex diseases 8 – 11 . Here we present a genome-wide association study for 233 circulating metabolic traits quantified by nuclear magnetic resonance spectroscopy in up to 136,016 participants from 33 cohorts. We identify more than 400 independent loci and assign probable causal genes at two-thirds of these using manual curation of plausible biological candidates. We highlight the importance of sample and participant characteristics that can have significant effects on genetic associations. We use detailed metabolic profiling of lipoprotein- and lipid-associated variants to better characterize how known lipid loci and novel loci affect lipoprotein metabolism at a granular level. We demonstrate the translational utility of comprehensively phenotyped molecular data, characterizing the metabolic associations of intrahepatic cholestasis of pregnancy. Finally, we observe substantial genetic pleiotropy for multiple metabolic pathways and illustrate the importance of careful instrument selection in Mendelian randomization analysis, revealing a putative causal relationship between acetone and hypertension. Our publicly available results provide a foundational resource for the community to examine the role of metabolism across diverse diseases. A meta-analysis of genome-wide association studies for 233 circulating metabolites from 33 cohorts reveals more than 400 loci and suggests probable causal genes, providing insights into metabolic pathways and disease aetiology.

The accurate monitoring and detection of acetone vapor are essential for environmental and human safety. Consequently, fern-like Fe[sub.2]O[sub.3] with hierarchical vein-like structures is synthesized via a concise hydrothermal method. Compared with pure fern-like Fe[sub.2]O[sub.3], fern-like Pd/PdO-Fe[sub.2]O[sub.3] shows the best acetone-sensing characteristics, in terms of lower operating temperature (180 °C), better selectivity and excellent long-term stability. More importantly, the response value of the Pd/PdO-Fe[sub.2]O[sub.3] sensor to 100 ppm acetone reaches as high as 73, which is 55% higher than that of pristine fern-like Fe[sub.2]O[sub.3]. This enhanced sensing performance can be ascribed to the synergistic effect between Pd/PdO and fern-like Fe[sub.2]O[sub.3]. On the one hand, Pd/PdO nanoparticles show favorable catalytic activity toward ionized oxygen molecules; meanwhile, the formation of the heterojunction between PdO and fern-like Fe[sub.2]O[sub.3] plays an important role. On the other hand, the hierarchical nature of fern-like Fe[sub.2]O[sub.3] promotes efficient gas diffusion throughout the structure. Based on its advantages, fern-like Pd/PdO-Fe[sub.2]O[sub.3] becomes a satisfactory candidate for acetone gas sensors.

The unique physicochemical properties of PEG-400 were imparted to (L)-prolinamide to afford a homogeneous, solvent-free, recyclable organocatalyst for scalable enantioselective aldol reaction between acetone and benzaldehyde to afford (R)-4-hydroxy-4-phenylbutan-2-one. The reaction was scaled up to afford 41 g of ketol in 95% yield and an ee of 91% using 30 mol% catalyst, 10 mol% trifluoroacetic acid (TFA), and 135 equivalent moles of acetone with respect to benzaldehyde. The catalyst was recycled 4 times with no obvious loss of activity. The role of PEG is discussed at the molecular level. This type of catalyst may provide new possibilities for the so-far-thwarted attempts at large-scale application of proline organocatalysis to asymmetric aldol reactions.

In the present work, the morphological, optical, and gas-sensing properties of La[sub.0.67]Ca[sub.0.2]Ba[sub.0.13]Fe[sub.0.97]M[sub.0.03]O[sub.3] (M = Ti, Cr, and Mn) nano-powders prepared via the auto-combustion route, were investigated. TEM images prove the nanoscale particle size of all the samples. Optical studies confirm the semiconductor behavior of the studied materials. The response of the prepared nano-powders towards the presence of two gas-reducing agents (ethanol and acetone) was investigated. From the resistance ratio under air and gas, it was possible to determine the response to different gases and deduce that La[sub.0.67]Ca[sub.0.2]Ba[sub.0.13]Fe[sub.0.97]Ti[sub.0.03]O[sub.3] presents the highest responses to ethanol and acetone. Likewise, we deduced that the prepared materials were able to detect low concentrations of ethanol and acetone gases.

Metal oxide semi-conductors are widely applied in various fields due to their low cost, easy processing, and good compatibility with microelectronic technology. In this study, ternary α-Fe[sub.2]O[sub.3]/TiO[sub.2]/Ti[sub.3]C[sub.2]T[sub.x] nanocomposites were prepared via simple hydrothermal and annealing treatments. The composition, morphology, and crystal structure of the samples were studied using XPS, SEM, EDS, XRD, and multiple other testing methods. The gas-sensing measurement results suggest that the response value (34.66) of the F/M-3 sensor is 3.5 times higher than the pure α-Fe[sub.2]O[sub.3] sensor (9.78) around 100 ppm acetone at 220°C, with a rapid response and recovery time (10/7 s). Furthermore, the sensors have an ultra-low detection limit (0.1 ppm acetone), excellent selectivity, and long-term stability. The improved sensitivity of the composites is mainly attributed to their excellent metal conductivity, the unique two-dimensional layered structure of Ti[sub.3]C[sub.2]T[sub.x], and the heterojunction formed between the nanocomposite materials. This research paves a new route for the preparation of MXene derivatives and metal oxide nanocomposites.

Sn-based electrocatalysts have recently been applied for CO.sub.2 reduction to generate fuels. Here, tin oxide crossed architectures (SnO) and petal-like Sn.sub.3O.sub.4 semiconductors were synthesized using the microwave-assisted hydrothermal method. The synthesized materials were applied in electrochemical reduction of CO.sub.2 and promoted the formation of methanol, ethanol and acetone. The best condition (greatest amount of products) was obtained with - 0.5 V vs Ag/AgCl for both electrocatalysts. For the first time, acetone formation was observed using both SnO and Sn.sub.3O.sub.4 materials. The SnO electrocatalyst exhibited the best electrochemical activity for CO.sub.2 reduction, ascribed to higher charge transfer corroborated by the higher current densities and lower resistance in the Nyquist diagram. Differences in methanol concentration obtained by the samples were ascribed to the different morphology and charge transfer over the films. The results showed that Sn-based electrocatalysts can be applied to generate important products, such as methanol and ethanol, aside from promoting acetone formation.

Although individual γ-Fe[sub.2]O[sub.3] and α-Fe[sub.2]O[sub.3] have been widely fabricated for gas sensors, their mixed phase of α/γ-Fe[sub.2]O[sub.3] might deliver excellent sensing properties. In this study, a facile solvothermal method was used to fabricate Fe-alkoxide. After thermal treatment, it was converted into γ-Fe[sub.2]O[sub.3], α-Fe[sub.2]O[sub.3] and their mixed-phase α/γ-Fe[sub.2]O[sub.3] with a nanosheets-assembled flower-like structure. We studied the influence of calcination temperature on the phase and sensing properties on acetone detection. The α/γ-Fe[sub.2]O[sub.3] which annealed at 400 °C included 18% α-Fe[sub.2]O[sub.3] and it exhibited excellent sensing performance towards acetone compared to that of γ-Fe[sub.2]O[sub.3] and α-Fe[sub.2]O[sub.3]. It showed a response of 353 to acetone with a concentration of 200 ppm, and a low limit of detection of 0.5 ppm at 160 °C. In addition, the change in responses with acetone concentration from 50 to 200 ppm shows a good linear relationship. Moreover, this material has good reproducibility and selectivity as well as a fast response time of 22 s and recovery time of 14 s to 200 ppm. Therefore, our mixed phase of α/γ-Fe[sub.2]O[sub.3] possesses great prospects for acetone detection.

Biobutanol is a promising biofuel due to the close resemblance of its fuel properties to gasoline, and it is produced via acetone-butanol-ethanol (ABE) fermentation using Clostridium species. However, lignin in the crystalline structure of the lignin-cellulose-hemicellulose biomass complex is not readily consumed by the Clostridium; thus, pretreatment is required to degrade this complex. During pretreatment, some fractions of cellulose and hemicellulose are converted into fermentable sugars, which are further converted to ABE. However, a major setback resulting from common pretreatment processes is the formation of sugar and lignin degradation compounds, including weak acids, furan derivatives, and phenolic compounds, which have inhibitory effects on the Clostridium. In addition, butanol concentration above 13 g/L in the fermentation broth is itself toxic to most Clostridium strain(s). This review summarizes the current state-of-the-art knowledge on the formation of microbial inhibitors during the most common lignocellulosic biomass pretreatment processes. Metabolic effects of inhibitors and their impacts on ABE production, as well as potential solutions for reducing inhibitor formation, such as optimizing pretreatment process parameters, using inhibitor tolerant strain(s) with high butanol yield ability, continuously recovering butanol during ABE fermentation, and adopting consolidated bioprocessing, are also discussed.