Tungsten oxide(WO3) nanocrystals have been synthesized successfully by a simple solvent-regulated solvothermal approach. The as-obtained sample was investigated by field emission scanning electron ...microscope (FESEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The NO2-sensing properties of WO3 nanocrystals were also investigated. It was found that the sensor displayed excellent gas sensing properties to NO2 at the optimal operating temperature of 100°C and behaved as an abnormal p-type semiconductor at near room temperature (RT). The response was about 28.3 and the response-recovery time was around 24 and 137s for 1ppm NO2, respectively, indicating that this structure could be a good candidate for gas sensors. In addition, the possible formation mechanism and gas sensing mechanism were proposed.
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•WO3 nanocrystals are synthesized via a simple solvothermal method.•The sensor shows an abnormal p-type behavior at near room temperature.•The result show excellent gas response to NO2 at low operating temperature.
Abstract
Taking the fiber ring of the core device of the fiber optic gyro as the research object, the temperature field simulation analysis of the fiber gyroscope was carried out by ANSYS finite ...element analysis software, and the structural optimization of the fiber gyroscope was carried out, which effectively improved the temperature field distribution uniformity of the fiber optic ring and reduced the overall thermal equilibrium temperature and time when the fiber gyro reached stability.
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•Co(acac)2 catalyzed carbonyl functionalization of PE.•DFT elucidated the alkyl radical mediated mechanism for the carbonylation.•Biodegradation efficiency of PE increased by 2.32 ...times after carbonylation.•Enhanced extracellular oxidases and hydrolase were obtained during biodegradation.
Polyethylene plastics are widely used in daily life since known for their resistance to biodegradation, but posing a significant environmental challenge. The biodegradation of polyethylene can contribute to environmental protection and facilitate energy conservation, in comparison with physical or chemical methodologies. However, the stable and inert C–C bond structure of polyethylene limits biodegradation effectiveness, leading to a slow breakdown rate and extended life cycle. In this study, Co(acac)2 was used as a catalyst to generate free radicals that activated the interface of low-density polyethylene, resulting in the formation of oxygen-containing functional groups. Under the condition of Co(acac)2-mediated catalysis at 120 °C for 24 h, the carbonyl index of polyethylene rose from 0 to 2.99. The weight-average molecular weight of polyethylene was reduced by 8.77 % compared to the control, leading to the generation of small molecules. The density functional theory elucidated showed that the active oxygen substitution in the single electron transfer reaction was driven by the high-energy intermediate alkyl radical. The bond energy of the resulting carbonyl functional group (CO) is 76.4 % lower than that of the original C–C bond, making it more susceptible to cleavage and depolymerization. Following 90 d of biodegradation, the laccase activity showed a 25 % increase compared to the control, indicating an improved oxidase release by chemical oxidation. The weight loss of low-density polyethylene was 23.91 %, and the microbial degradation efficiency was 2.32 times higher. This strategy significantly improves the ability of microorganisms to degrade low-density polyethylene and is a novel approach to the design of pathways for the polyolefin degradation.
In this paper, solvothermally synthesized tungsten oxide (WO3) nanocrystals were modified by changing the reaction temperature. The effect of reaction temperature on the morphology and NO2 sensing ...properties of WO3 nanocrystals was investigated. Numerous analytical techniques, such as field emission scanning electron microscope (FESEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM), have been employed to characterize their feature. The NO2-sensing properties of the sensors based on the WO3 nanocrystals with various morphologies to NO2 with the concentration ranging from 100 ppb to 3 ppm were examined at different temperatures ranging from room temperature (RT) to 250 °C. It is found that the solvothermal reaction temperature played a critical role on determining the morphology of the WO3 nanocrystals, and all the sensors exhibited a high response, rapid response characteristics and excellent selectivity toward NO2 at low operating temperature. Especially, the 170 and 180 °C solvothermally synthesized sensors showed an anomalous p-type conductive behavior at approximate below 38 and 55 °C, respectively.
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•WO3 nanocrystals are synthesized via a simple solvothermal method.•The morphology depends on the solvothermal reaction temperature.•The 170 and 180 °C synthesized sensors show a p-type behavior at room temperature.•The results show excellent gas response to NO2 at low operating temperature.
A star-shaped polymer enables inverted perovskite solar cells with efficiency over 22% and a very high fill factor of 0.862.
Stabilizing high-efficiency perovskite solar cells (PSCs) at operating ...conditions remains an unresolved issue hampering its large-scale commercial deployment. Here, we report a star-shaped polymer to improve charge transport and inhibit ion migration at the perovskite interface. The incorporation of multiple chemical anchor sites in the star-shaped polymer branches strongly controls the crystallization of perovskite film with lower trap density and higher carrier mobility and thus inhibits the nonradiative recombination and reduces the charge-transport loss. Consequently, the modified inverted PSCs show an optimal power conversion efficiency of 22.1% and a very high fill factor (FF) of 0.862, corresponding to 95.4% of the Shockley-Queisser limited FF (0.904) of PSCs with a 1.59-eV bandgap. The modified devices exhibit excellent long-term operational and thermal stability at the maximum power point for 1000 hours at 45°C under continuous one-sun illumination without any significant loss of efficiency.
•WO3 nanocrystals with various morphologies are synthesized via solvothermal method.•The morphology depends on the volume ratio of water in the reaction solvent.•Pure WO3 nanosheets show an abnormal ...p-type behavior at temperature below 55°C.•The results show excellent gas response to NO2 at low temperature.
Tungsten oxide (WO3) nanocrystals with various nanomorphologies were synthesized by solvothermal method using tungsten hexachloride (WCl6) as a raw material and pure ethylene glycol (EG) or water–EG as reaction solvent, and the NO2-sensing properties of the WO3 nanocrystals were studied. The morphology and crystal structure were investigated by field emission scanning electron microscope (SEM), X-ray diffraction (XRD) and transmission electron microscope (TEM). The NO2 gas sensing properties of WO3 nanocrystals were investigated at different temperatures ranging from room temperature (∼25°C) to 250°C over NO2 concentration ranging from 0.1 to 3ppm. The results indicate that the morphology and crystal phase of the WO3 nanocrystals depended on the water content in water–EG mixed solvent. With the increase of water content, the crystalline phase transformed from hexagonal to monoclinic. At the operating temperature below 55°C, the sensor synthesized in EG solvent showed an abnormal p-type conductive behavior. It is found that all the sensors exhibit high sensor responses and rapid response characteristics to different concentrations of NO2, and their highest sensor responses are achieved at 100 or 50°C.
MicroRNAs (miRNAs) play a vital role in muscle development by binding to messenger RNAs (mRNAs). Based on prenatal skeletal muscle at 33, 65 and 90 days post-coitus (dpc) from Landrace, Tongcheng and ...Wuzhishan pigs, we carried out integrated analysis of miRNA and mRNA expression profiling. We identified 33, 18 and 67 differentially expressed miRNAs and 290, 91 and 502 mRNA targets in Landrace, Tongcheng and Wuzhishan pigs, respectively. Subsequently, 12 mRNAs and 3 miRNAs differentially expressed were validated using quantitative real-time PCR (qPCR), and 5 predicted miRNA targets were confirmed via dual luciferase reporter or western blot assays. We identified a set of miRNAs and mRNA genes differentially expressed in muscle development. Gene ontology (GO) enrichment analysis suggests that the miRNA targets are primarily involved in muscle contraction, muscle development and negative regulation of cell proliferation. Our data indicated that more mRNAs are regulated by miRNAs at earlier stages than at later stages of muscle development. Landrace and Tongcheng pigs also had longer phases of myoblast proliferation than Wuzhishan pigs. This study will be helpful to further explore miRNA-mRNA interactions in myogenesis and aid to uncover the molecular mechanisms of muscle development and phenotype variance in pigs.
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•The visible-light-driven photo-reduction of Cr(VI) by formic acid was achieved.•Study on the light intensity and wavelength suggests a light-induced mechanism.•DFT simulation ...predicts the light-induced charge transfer process.•EPR analysis shows a stepwise pathway with Cr(V) and Cr(IV) as the intermediates.•This reaction is applicable for the treatment of Cr(VI) contaminated wastewater.
To study the applicability and mechanism of the visible-light-driven photo-reduction of Cr(VI) is important since it will elucidate the chromium cycle in natural circumstances, and since this reduction reaction is important in treating wastewater contaminated by Cr(VI). Herein, we conducted an in-depth mechanism study for this process using formic acid as electron donor. The positive dependence of the Cr(VI) conversion on the incident light intensity and the good match between the apparent quantum yield (0.0039–0.39%) and the light absorption spectrum (550–365 nm) suggests a light-induced mechanism. The light-induced charge transfer occurs through the ligand-to-metal charge transfer state of the complex which forms between one dichromate molecule and two formic acid molecules through symmetrical or asymmetrical configuration as demonstrated by DFT simulation. EPR analysis further proves that this reaction occurs through a stepwise process with Cr(V) and Cr(IV) as the intermediates. The practical use of this photochemical procedure with broad electron donor scope and wide pH, reaction temperature, and initial Cr(VI) concentration ranges, is proven by the application potential evaluation. The efficient reduction of Cr(VI) by formic acid under sunlight further proves the applicability of this photochemical procedure for the treatment of Cr(VI) contaminated wastewater. Development of the present study into both the treatment of Cr(VI) contaminated wastewater, and other visible-light-driven photo-redox reactions between metals and organics are the subject of further research and results can be expected in the near future.
Biohydrogen is a clean and renewable energy, but the low yield caused by the lack of reducing power in cells greatly restricts the industrialization of biohydrogen production. Photo-biohybrid systems ...(PBSs) can integrate the high light energy utilization efficiency of photocatalysts with the excellent catalytic performance of microorganisms. Here, gold nanoparticles were targeted into Clostridium butyricum as intracellular photosensitizers to construct a PBS that could efficiently produce biohydrogen under visible light, with the apparent quantum yield as high as 19.31%. Compared with the dark-fermented C. butyricum, the biohydrogen production of PBS increased by 88.74%. The mechanism of photoelectrons from Au NPs to C. butyricum was elucidated by the transcriptome. Compared with the dark-fermented biohybrids, the expressions of biohydrogen generation-related enzymes, such as hydrogenase and pyruvate formate lyase genes, in the PBS were all upregulated more than 2 times. Furthermore, the genes of riboflavin synthase, electron transfer flavoprotein (ETF), and FAD-dependent oxidoreductase, which are closely related to electron transformation, were all significantly upregulated. The photoelectrons were transferred to the hydrogenase via ETF and FAD2+ to enhance biohydrogen production, independent of pyruvate decomposition. This PBS provides theoretical guidance for constructing an efficient light-driven microbial manufacturing system.
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