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The ester-synthesis enzymes influenced by environmental factors during Daqu-making process largely determine the flavor of Chinese liquor, but the main ester-synthesis enzyme and its key influencer remain unclear. Here, the volatile ester profiles over the whole Daqu-making process, under different treatments, for at least 90 days, were carefully analyzed, and the potential ester-synthesis enzymes, as well as their dependently environmental factors, were explored.In the detected 46 volatile esters, only the short-chain (C4-C8) and medium-chain (C9-C13) ester content obviously changed, as the primary contributor discriminating different samples. Their trends were both consistent with that of the alcohols and the primary metabolism, which included alcohol acyltransferases (AATs) reaction with alcohols and acyl-CoAs as the substrates. Among the potential ester-synthesis enzymes, the typical AAT activity also exhibited the highest correlation with the short- and medium-chain esters (r 0.78, P 0.05). The Mantel test between environmental factors and ester production showed that temperature of Daqu was directly correlated with the short-chain esters (r = 0.58, P 0.01) and AAT activity (r = 0.56, P 0.01). Further, the short- and medium-chain ester content in Daqu under the treatment nearer to the reported optimal temperature of 40-50 °C of AATs reaction was overall higher than that of the other treatment Daqu.This study revealed that the temperature-dependent AATs reaction was the main enzymatic method producing the short- and medium-chain esters over the whole Daqu-making process. The results could contribute to the flavor improvement of Baijiu. © 2022 Society of Chemical Industry.

The saccharification function of daqu is usually characterized by two indicators: saccharification power and liquefaction power. Daqu provides diverse microbial saccharifying enzymes for hydrolyzing carbohydrate in Baijiu fermenting grain. Obviously, the composition of microbial communities and enzymatic genes in different types of daqu cultured at varied temperatures is different. However, these differences in saccharification function are not fully understood.The findings suggested that the saccharification power and liquefaction power of jiangxiangxing daqu were lower than those of nongxiangxing daqu throughout the production process. We employed metagenomics to find evidence that a mode of multiple saccharifying enzymes involving amylase, cellulase and hemicellulase originating from various microbes exists in daqu. Moreover, a totality of 541 related differential genes were obtained, some of which, annotated to genera of Aspergillus, Lactobacillus and Weissella, were significantly enriched (P 0.05) in nongxiangxing daqu, while others, annotated to thermophilic genera of Virgibacillus, Bacillus, Kroppenstedtia and Saccharopolyspora, showed a higher relative abundance in jiangxiangxing daqu (P 0.05).Various microbial communities of daqu showed diverse saccharification capacity during cultivation of different parameters. These findings are helpful in comprehending the saccharification functional genes of daqu. © 2022 Society of Chemical Industry.

Thermal oxidation and hydrogen annealing were applied on a 100 μm thick Al-doped p-type 4H-SiC epitaxial wafer to modulate the minority carrier lifetime, which was investigated by microwave photoconductive decay (μ-PCD). The minority carrier lifetime decreased after each thermal oxidation. On the contrary, with the hydrogen annealing time increasing to 3 hours, the minority carrier lifetime increased from 1.1 μs (as-grown) to 3.14 μs and then saturated after the annealing time reached 4 hours. The increase of surface roughness from 0.236 nm to 0.316 nm may also be one of the reasons for limiting the further improvement of the minority carrier lifetimes. Moreover, the whole wafer mappings of minority carrier lifetimes before and after hydrogen annealing were measured and discussed. The average minority carrier lifetime was up to 1.94 μs and non-uniformity of carrier lifetime reached 38% after 4-hour hydrogen annealing. The increasing minority carrier lifetimes could be attributed to the double mechanisms of excess carbon atoms diffusion caused by selective etching of Si atoms and passivation of deep-level defects by hydrogen atoms.

Graphene/SiC/graphene photodetectors were fabricated by epitaxial graphene prepared on semi-insulated 4H-SiC (0001) using the ultra-high vacuum high-temperature thermal decomposition method. The device exhibits a maximum responsivity of 0.01 A/W, a 103 UV–visible rejection ratio, and a high detectivity of 1.34 × 1012 Jones with a ultra-low saturation dark current of 3 × 10−13 A. Interfacial quantum states were adopted at graphene/4H-SiC heterojunction for tuning the Schottky barrier by reverse bias. The extracted Schottky barrier heights decrease from 0.91 to 0.81 eV with bias due to the upward shift of the charge-doped graphene's Fermi level. The peak responsivity of the detector is tuned from 260 to 300 nm, which indicates SiC photogenerated carriers are released from the interfacial quantum states by applied bias. More carriers transit over the Schottky barrier so that the photodetectors achieve high photoelectric conversion.

Chinese Baijiu, the national liquor of China, is also one of the world-renowned distilled spirits. Jiuqu, a fermentation starter, is the masterpiece of traditional food biotechnology with a long history in China. Compared to western brewing technology of using malt and yeast in stages, the mode of using jiuqu (or combined with pit mud, a activated sludge) for Baijiu brewing is recognized in China. So far, culture-dependent, molecular biology technology and omics approaches have provided deeper insights into study the jiuqu microbiome. Jiuqu is considered to be a microecosystem with diverse and unique microorganisms, in which fascinating features of saccharification, alcohol fermentation, and flavors generation appear. However, knowledge about microbial diversity of jiuqu and their roles involved in Baijiu fermentation is still fragmentary and not systematic enough. Therefore, this review introduced and compared three basic types of jiuqu starter: daqu, xiaoqu and fuqu. We described in detail the microbial succession during preparation of jiuqu, aiming to emphasize that succession process promotes to formation of its stable distribution of microbial community. We also summarized the main species originated from jiuqu and their various properties. Furthermore, reported results about fermentation features of saccharification, alcohol fermentation, and flavors generation in jiuqu microbiome were generalized, and these features were emphasized to play the potential role in Baijiu brewing. Although the current work is limited, promising clues can be traced for future investigation on comprehensive metabolic processes in jiuqu. KEY POINTS: • The various microorganisms present in jiuqu, and each has its specific property. • Microbial succession in preparation promotes to distribution of microbial community. • Jiuqu contributes the potential of saccharification, fermentation and flavors generation to Baijiu brewing.

The electrical properties of Ti/Au contacts to anatase TiO2 nanocrystal films are investigated under different thermal annealing temperature (300–500 °C) in a N2 ambient. The as-deposited contact shows a non-linear current–voltage (I – V) property. However, after being annealed at 300 °C and 400 °C, the samples exhibit nearly ohmic I – V behaviors with currents at 5 V bias higher than that of as-deposited one by about three and seven times, respectively. When the annealing temperature is increased to 500 °C, the ohmic contact transform to Schottky contact. The influence of annealing temperatures on Ti/Au contacts to anatase TiO2 nanocrystal films depends on the interdiffusion behavior between the electrode layers and TiO2 films, which was investigated by Auger electron spectroscopy. Possible mechanisms are proposed to explain the influence of annealing temperature on the electrical properties of Ti/Au contacts to anatase TiO2 nanocrystal films.

MgxZn1−xO (x = 0.05, 0.10, 0.15, and 0.20) films prepared on quartz substrates by the sol–gel method were characterized and studied. According to scanning electron microscopy and x-ray diffraction data, the MgxZn1−xO films exhibited a particle-stacking morphology and a hexagonal wurtzite crystal structure. An increase in Mg content led to an obvious increase in particle size. However, a weakening of the hexagonal wurtzite structure was observed and indicated the transition of the MgxZn1−xO crystal structure, which was also confirmed by the Raman spectra results. An increase in bandgap energy from 3.38 eV to 3.55 eV with increased Mg content was determined from the transmittance spectra. Ultraviolet photodetectors based on MgxZn1−xO with interdigital electrodes were then fabricated. Dark current as low as 10 pA (corresponding to 5 nA/cm2) under bias of 10 V was achieved. A blueshift of the peak wavelength and cutoff wavelength was observed with increasing Mg content. Noise equivalent power as low as 2 × 10−15 W was achieved, detectivity was found to be about 1.2 × 1011 cm Hz1/2/W, and quantum efficiency was nearly 100%, which was related to the photoconductive gain.

Recently, organic-inorganic hybrid perovskites (OIHPs) are rising as promising candidates for light-emitting applications, due to their superior optical properties. High performance light-emitting applications such as scintillators require minimum non-radiative recombination and high fractions of radiative recombination. Here, we report a simple solution-processing strategy for the synthesis of funnel-type CH3NH3(MA)PbCl3/CH3NH3(MA)PbBrxCl3-x heterostructure perovskite materials that improve the light emission performances. The single crystal X-ray diffraction pattern indicates that the lattice mismatch is only ∼3.24% in the heterointerface. The halide gradient is helpful for driving the photoexcited carriers from the internal high bandgap material to the low bandgap light-emitter layer. The steady-state photoluminescence (PL) and radioluminescence (RL) spectra show that the luminescence intensity has been significantly improved by this heterostructure perovskite. Time-resolved photoluminescence (TRPL) exhibits carrier transport along the halide gradient. Our research suggests that the gradient halide perovskite heterostructure with specific optical properties could be a prospect for commercial scintillator applications.

A 4H-SiC trench gate metal–oxide–semiconductor field-effect transistor (UMOSFET) with semi-super-junction shielded structure (SS-UMOS) is proposed and compared with conventional trench MOSFET (CT-UMOS) in this work. The advantage of the proposed structure is given by comprehensive study of the mechanism of the local semi-super-junction structure at the bottom of the trench MOSFET. In particular, the influence of the bias condition of the p-pillar at the bottom of the trench on the static and dynamic performances of the device is compared and revealed. The on-resistance of SS-UMOS with grounded (G) and ungrounded (NG) p-pillar is reduced by 52% (G) and 71% (NG) compared to CT-UMOS, respectively. Additionally, gate oxide in the GSS-UMOS is fully protected by the p-shield layer as well as semi-super-junction structure under the trench and p-base regions. Thus, a reduced electric-field of 2 MV/cm can be achieved at the corner of the p-shield layer. However, the quasi-intrinsic protective layer cannot be formed in NGSS-UMOS due to the charge storage effect in the floating p-pillar, resulting in a large electric field of 2.7 MV/cm at the gate oxide layer. Moreover, the total switching loss of GSS-UMOS is 1.95 mJ/cm2 and is reduced by 18% compared with CT-UMOS. On the contrary, the NGSS-UMOS has the slowest overall switching speed due to the weakened shielding effect of the p-pillar and the largest gate-to-drain capacitance among the three. The proposed GSS-UMOS plays an important role in high-voltage and high-frequency applications, and will provide a valuable idea for device design and circuit applications.

Scintillators that convert ionization radiation photons to UV-visible photons have attracted extraordinary attention. Traditional scintillators are associated with a vacuum photomultiplier tube that faces strict constraints of fragility, magnetic fields, and operated voltage, or coupled to a silicon photomultiplier (SiPM) with optical silicone grease. Here, we report a high-performance radiation detector with an indirect photon-to-photon conversion radiation detection model based on perovskite single crystals (SCs), where perovskite SCs have been directly integrated into the window of SiPM by using the solution growth method at low temperature. Tunable X (γ)-ray excited light emission in the range of 414 to 600 nm is obtained with different concentrations of Br doping, which greatly matches the response wavelength of SiPM. Small Br-doped CH

Backgroud Chinese Luzhou-flavor baijiu (LFB) was fermented in an underground cellar, and the bottom and side of the cellar were covered with pit muds (PMs), where the metabolic activity of the microorganisms had a significant effect on the LFB quality. PMs can be divided into aged pit mud (AP) and degenerated pit mud (DP), thus, the qualities of LFB generated from AP and DP were different. In this essay, metatranscriptomics method was applied to illustrate the differences of the two PMs, as well as to search out the pivotal microorganisms and genes influencing the quality of LFB. Results Archaea, Clostridium and some thermophilic microorganisms might bring significant effect in AP, while the active eukaryota and Anaeromyxobacter would cause degeneration in PM. Also, the metabolism of carbohydrate and amino acid were more active in AP. What is more, carbohydrate, amino acid and their derivant can produce important organic acids via the activity of the microorganisms in PMs. There were eight critical enzymes noticed in the organic acids metabolic pathway, which were more actively expressed in AP, demonstrating active expression of the critical genes related to organic acid metabolism could have a positive effect on LFB quality. Conclusion This study identified specific differences in active microorganisms, active expressed genes and the expression levels of key genes in vital metabolic pathway between AP and DP. Which may be the actual reason for the differences in the quality of LFB made from different PMs. Mastering these results will provide assistance to improve the quality of LFB. © 2021 Society of Chemical Industry.

As the main by-product of Chinese strong-flavor liquor, yellow water plays an important role in the formation of flavor components. Yellow water from different fermentation periods (30th day, 45th day, 60th day) was selected to analyze the aroma components by Headspace solid phase micro-extraction Gas Chromatography&ndash, Mass Spectrometry, and the microorganism community was evaluated by high-throughput sequencing technology and bioinformatics analysis of DNA. As the fermentation time was prolonged, the main flavor components significantly increased, and the amount of the common microbial population between yellow water and pit mud increased gradually. Among the common microorganisms, Lactobacillus accounted for the largest proportion, at about 56.96%. The microbes in the yellow water mainly belonged to Firmicutes. The abundance of Bacilli (the main bacteria) gradually decreased with time, at 87.60% at the 30th day down to 68.87% at the 60th day, but Clostridia gradually increased from 10.29% to 27.48%. At the genus level, some microbes increased significantly from the 30th day to 60th day, such as Caproiciproducens, which increased from 2.65% to 6.30%, and Sedimentibacter, increasing from 0.47% to 2.49%. RDA analysis indicated that the main aroma components were positively correlated with Clostridia and negatively correlated with Bacilli.

In this work, a high-performance and stable UV photodetector is reported that is based on solution-processed lead bulk Cs4PbI6 single crystals. The Cs4PbI6 single crystals are demonstrated with unique 0D structural and high visible transparent with the wide optical bandgap at 3.46 eV. The crystals exhibit excellent electrical properties with a large μτ value of 9.5×10-4 cm2 V-1 and a low trap density of 1.7×1010 cm-3. Further, a symmetrical Au-semiconductor-Au structured ultraviolet photodetector based on Cs4PbI6 single crystals has been achieved. The device has been demonstrated with good UV detection performances at 1 V bias: low dark current density of 63.6 nA cm-2, the ratio of the photocurrent to the dark current was about 728 times, fast time profile (response time and recovery time are 11.65 and 12.80 μs, respectively), high UV response (responsivity of 5.07 mA W-1). In addition, the device has good environmental stability under the temperature from 303 K to 404 K and air. This work proves that Cs4PbI6 is a competitive candidate for ultraviolet photon detectors with high detection performance and strong environmental stability.

Hafnium oxide (HfO $_2$ ) thin films were deposited on quartz substrate by radio frequency magnetron sputtering with power from 160 W to 240 W. The optical and microstructural properties of samples before and after annealing were characterized by XRD, XPS, UV-VIS-NIR spectrophotometer and ellipsometer. The results show optical transmittances with low absorption in wavelength range above $\lambda$ =200 nm for all samples. The appropriate annealing can transfer the amorphous state of as-deposited films to the crystal film, contribute to the growth of nanocrystalline and compressive stress, optimize the stoichiometry of the film and systematically improve film density and the refractive index. In consideration of the stability of proper refractive index (> 2) and high optical transmittance in UV band, HfO $_2$ films deposited approximately at 220 W can be used in UV anti-reflection system.

We describe synthesis of high-quality crystalline ZnO thin films via hydrothermal solution method at low temperature. A variety of ZnO material structures (nanowires, nanorods , and thin films) have been obtained with various Cu(NO 3)2 concentrations of the precursor solution. Interdigitated finger metal-semiconductor-metal structure UV photodetector with gold Schottky contact is fabricated based on the ZnO materials, which has been employed to investigate the UV photo detection performance. Our results indicate that the performance of the device depends on the structure of the ZnO materials. With Cu(NO 3)2 concentration of 0.25 mM, the photodetector with the lowest dark current of 1.88 nA, responsivity of 1.46A/W, and UV-to-Visible rejection ratio up to four orders at 1 V bias has been achieved.

We developed a Joule heating decomposition (JHD) method, which applied direct current on the SiC for the epitaxial growth of multi-layer graphene (MLG) films on Si-terminated (0001) face of the high doping 4H-SiC substrate. By this JHD method, the growth time for preparing MLG was only several minutes. Raman spectroscopy was employed to study the influence of the temperature caused by the Joule heating on the quality and the uniformity of the sample. Then, other properties, such as the strain, the layer’s number, and the electric characteristics, of the MLG were studied in details. It was found that the quality of the MLG was substantially dependent on the growth temperature (operation current) and the growth time, while the layer’s number was only dependent on the growth temperature but not the growth time. Finally, less-defect and homogeneous MLG (~ 45 layers) with an area of ~ 12 × 5 mm2 could be obtained at a heating temperature of ~ 1470 °C with duration time of 5 min. By using the linear transmission line method, the specific contact resistance of Au and MLG was 5.03 × 10−5 Ω cm2, and the sheet resistance was 52.36 Ω/sq, respectively.

In order to analyze the effect of Chinese herbs on the three major enzyme activities: glucoamylase, protease and esterase as well as the biomass of the Monascus spp., a high quality Red mold rice (RMR) with Chinese herbs was developed. The new RMR demonstrated higher enzyme activity and biomass than the blank control. The glucoamylase, protease and esterase activity were increased to 518.03 U/g, 10.10 g/kg and 30.99 g/kg, respectively. Simultaneously, the biomass increased to 59.82 g/kg. With its application in rice wine, the alcohol yield ratio, total amino acid and the fragrance composition content increased obviously, respectively, and the organic acid content and the antioxidant capacity in vitro increased markedly.

4H-SiC ultraviolet p-i-n photodiodes with four different epitaxial structures were fabricated. The experimental results prove that both a thin P+-type Ohmic contact layer and a thick intrinsic layer were indispensible for a high-performance ultraviolet p-i-n photodiode. A 4H-SiC p-i-n photodiode with responsivity as high as 0.139 A/W at 278 nm incident wavelength was achieved. Meanwhile, within a certain wavelength range, the peak response wavelength of an ultraviolet p-i-n photodiode would be modulated by properly varying the thicknesses of P+-type layer and the intrinsic layer. Moreover, the theoretical calculation was carried out to further authorise the experimental results.

Sichuan industrial paocai and traditional home-made paocai have different aroma profiles due to different manufacturing techniques, but detailed information about the aroma profiles and aroma-producing microorganism of Sichuan industrial paocai remain largely elusive. For this reason, we established and validated an external standard method of headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC–MS) combined with gas chromatography–olfactometry (GC-O) for identification and accurate quantitation of aroma-active compounds in Sichuan industrial paocai. This method was combined with 16S rRNA amplicon sequencing to comprehensively analyze the aroma and bacteria profiles of Sichuan industrial paocai. A total of 121 volatile compounds were identified, among which 36 odorants were identified as aroma-active compounds with aroma intensities (AIs) ranging from 0.67 to 5.00 by GC-O. The types of aroma-active compounds in Sichuan industrial paocai were variety-specific to some extent, but the aroma-active compounds shared by different varieties of Sichuan industrial paocai (i.e., skeleton aroma-active compounds) were phenylethyl alcohol, acetic acid, butanoic acid, 2-methylbutanoic acid, ethyl hexanoate, 4-ethylphenol and 4-ethylguaiacol. Moreover, 17 key aroma-active compounds of AI > 1 in radish paocai were quantitated by external standard method, and their odor activity values (OAVs) were calculated based on the odor thresholds. Further, 12 aroma-active compounds with OAV ≥ 1 in one of the radish paocai were selected to construct the recombination model, which revealed good agreement with the original sample. Furthermore, Lactobacillus, Pediococcus, Pseudomonas and Sphingomonas were the dominant bacteria in Sichuan industrial paocai. Correlation analysis between 16 dominant bacteria and 36 aroma-active compounds showed that Pediococcus, Arcobacter and Lactobacillus could be the core aroma-producing bacteria of Sichuan industrial paocai.

We describe the synthesis of ZnO nanostructures materials on quartz substrates by a simple two-step thermal oxidation process. Firstly, a thin layer of metallic Zn films are oxidized in nitrogen atmosphere at 350 ℃, and then the samples annealed at high temperature (from 600 to 800 ℃) to improve the crystal quality. The properties of the materials are characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy and UV–Visible spectroscopy at room temperature. The results show that nano porous structure materials have been formed after the samples annealed at high temperature. Since the small grain size and grain boundary induced effect of conduction band bending, the optical band gap shifts to low energy.

In this study, the free amino acid content of traditional Zajiu, ‘small-scale trial’ Zajiu and commercial Zajiu, produced from hull-less barley, was determined using an automatic amino acid analyser. The amino acid nutritive value of the tested wines were measured using the ratio coefficient of amino acid and linear-regression analysis. A Chinese yellow wine was used as a reference. At least 17 types of free amino acids were found in all four of the tested wines. Chinese yellow wine exhibited the highest total amino acid content (3094 mg/L), followed by traditional Zajiu (2875 mg/L) and commercial Zajiu (2042 mg/L). However, Zajius had a higher essential amino acids/total amino acid ratio than Chinese yellow wine, and their composition of essencial amino acid more closely matched the recommendations of the World Health Organization/UN Food and Agriculture Organization. Analysis based on linear regression showed that the amino acid nutritive value of the wines was ranked from high to low as follows: commercial Zajiu, traditional Zajiu, Chinese yellow wine and ‘small-scale trial’ Zajiu. These results provide some information on the amino acid nutritional quality of Chinese Zajiu, and a new method for the amino acid nutritive value assessment of foods and beverages. Copyright © 2017 The Institute of Brewing & Distilling

Summary Sichuan pickle is a traditional Chinese food fermented mainly by lactic acid bacteria (LAB). In this study, effect of adding Lycium barbarum on Sichuan pickle fermentation was investigated using kinetic modelling and correlation analysis. It was found that L. barbarum addition not only increased the amount of LAB, the total acid content and antioxidant capacity, but also improved the organoleptic quality and reduced nitrite content of the pickle considerably. Model-based analyses revealed that L. barbarum addition increased the growth rate and decreased the death rate of LAB. The increase in antioxidant capacity of the pickle, especially the phenolics, can at least partly be attributed to its transferring from the L. barbarum. Correlation analysis results suggest that the nitrite reduction in pickle is closely related with pH value decrease and the increase in acids, and LAB, yeast and acids may all make contribution to the antioxidant capacity of the pickle.

Hybrid methylammonium lead tribromide (MAPbBr3) perovskite has attracted great attention in ionization radiation detection. However, the charge collection remains a challenge. Here, fast response and high-sensitivity X-ray detection based on MAPbBr3 single crystals with a surface barrier Schottky diode has been achieved at room temperature. The Schottky surface barrier can overcome the large leakage current at a high electrical field, enabling us to reduce the noise and increase the charge collection efficiency. This surface barrier device has been demonstrated a 3 times improvement over the photoconductor based X-ray detector, which enables usage in nuclear medicine, especially for X-ray imaging technology.

We reported on metal–semiconductor–metal ultraviolet (UV) photodetector (PD) based on pulse-laser-deposited TiNbO2 alloy film. The TiNbO2 PD exhibited a low dark current density of $\sim 0.46$ nA/cm2, a high UV-to-visible rejection ratio of $\sim 10^{6}$ , and a high responsivity of $\sim 0.22$ A/W under the illumination of 310-nm light ( $\sim 1.86$ mW/cm2). Interestingly, the TiNbO2 alloy PD presents a blue-shift cutoff wavelength of 350 nm due to quantum size effect and alloy characteristics, which would be promising for the further research in the UV detection.

The bacterial community in the pit mud of a Luzhou-flavour liquor distillery in different regions was analysed by combined polymerase chain reaction–denaturing gradient gel electrophoresis (PCR-DGGE) and quantitative PCR (qPCR) in order to distinguish a matured and a degenerated pit mud, judged according to sensory and physicochemical characteristics. The phyla Firmicutes, Cloacimonetes, Actinobacteria, Proteobacteria, Synergistetes and Unclassified Bacteria were detected. Firmicutes predominated in the pit mud. The diversity and homogeneity of the bacterial community in the matured pit mud were superior to those in the degenerated pit mud in the same distillery. There were significant differences in the bacterial community structure between the matured and degenerated pit mud. Moreover, the bacterial community in the degenerated pit mud samples was similar, which indicated that the bacterial community in the degenerated pit mud did not change within the two different regions. However, the bacterial community in matured pit mud samples was different, demonstrating that there were visible differences in the bacterial community between the samples of matured pit mud collected from the Luzhou-flavour liquor distilleries in the two different regions. Notably, the quantity of Actinobacteria in the matured and the degenerated pit mud was found to be different by quantitative analysis. Potentially, the Actinobacteria could serve as an indicator bacteria to distinguish between matured and degenerated pit muds. Copyright © 2015 The Institute of Brewing & Distilling

Graphene/4H-SiC/graphene photodetectors, as well as graphene/4H-SiC heterojunctions, have been fabricated and characterized by utilizing a heating decomposition method. High-quality graphene has been grown on an n− doped 4H-SiC substrate along with a 900 °C hydrogenation process. Temperature-dependent current–voltage characteristics of the graphene/4H-SiC heterojunction have been measured to obtain the Schottky barrier height. The bias-dependent Schottky barrier height (varying from 0.43 eV to 0.41 eV) was found and could result mainly from the electrical doping and Fermi level shifting in graphene. With the increase in the bias, the unsaturated dark current of graphene/4H-SiC/graphene photodetectors indicated the electron diffusion at the graphene/4H-SiC heterojunction. The increased responsivity peaks come from the absorption of the graphene layer in the UV range and the long lifetime of photo-induced thermal electronic carriers being contributed to the bandgap shrinking of graphene and reduction of the Schottky barrier height. The photodetectors biased at 6 V showed a responsivity of 40 A/W, an external quantum efficiency of 1.38 × 104%, and a detectivity of 9 × 1011 Jones, which are larger than those of previously reported similar devices based on graphene/SiO2 or graphene/SiC.

On the semi-insulating 4H–SiC (0001) surface, hydrogenated multilayers graphene (MLG) were epitaxially prepared by the method of Joule heating decomposition in the hydrogen atmosphere. The structural and chemical characteristics of multilayers graphene have been elaborately analyzed by the X-ray photoelectron and Raman spectroscopies, showing the level of hydrogenation being promoted with the increase of hydrogen pressure. Then, diodes with MLG/4H–SiC contact were fabricated and studied, proving that the Schottky barrier height (SBH) of MLG/4H–SiC junction was enhanced by the hydrogenation. By studying the typical current-voltage characteristics, the SBH was observed to be heightened from 0.84 eV to 1.0 eV along with the hydrogen pressure increasing from 10−2 mbar to 102 mbar. Finally, graphene-semiconductor-graphene photodetectors were fabricated, showing peak responsivity as high as~ 0.9 A/W and external quantum efficiency of 345%, under the 324 nm illumination and biased at 3V.

We report a facile route to the synthesis of Ag@Au–Pt trimetallic nanocubes in which the Ag, Au, and Pt atoms are exposed at the corners, side faces, and edges, respectively. Our success relies on the use of Ag@Au nanocubes, with Ag2O patches at the corners and Au on the side faces and edges, as seeds for the site-selective deposition of Pt on the edges only in a reaction system containing ascorbic acid (H2Asc) and poly(vinylpyrrolidone). At an initial pH of 3.2, H2Asc can dissolve the Ag2O patches, exposing the Ag atoms at the corners of a nanocube. Upon the injection of the H2PtCl6 precursor, the Pt atoms derived from the reduction by both H2Asc and Ag are preferentially deposited on the edges, leading to the formation of Ag@Au–Pt trimetallic nanocubes. We demonstrate the use of 2,6-dimethylphenyl isocyanide as a molecular probe to confirm and monitor the deposition of Pt atoms on the edges of nanocubes through surface-enhanced Raman scattering (SERS). We further explore the use of these bifunctional trimetallic nanoparticles with integrated plasmonic and catalytic properties for in situ SERS monitoring the reduction of 4-nitrothiophenol by NaBH4. Upon the removal of Ag via H2O2 etching, the Ag@Au–Pt nanocubes evolve into trimetallic nanoboxes with a wall thickness of about 2 nm and well-defined openings at the corners. The trimetallic nanoboxes embrace plasmon resonance peaks in the near-infrared region with potential in biomedical applications.

The authors report on high quality TiO2 epilayers grown on lattice-matched LaAlO3 substrates by pulsed laser deposition. A prototype of metal–semiconductor–metal ultraviolet (UV) photodetector based on TiO2 was fabricated by employing Au as the Schottky contact metal. The UV–visible transmittance spectrum of the TiO2 epilayer and the spectral response of the photodetector reveal that the deposited anatase TiO2 thin film exhibits excellent visible-blind UV characteristics with an optical bandgap of 3.25 eV. In addition, the fabricated photodetector exhibits a high UV-to-visible rejection ratio (R270 nm/R400 nm) of 105 while displaying a low dark current of 0.25 pA under 5 V bias and a high responsivity of 0.21 A/W, suggesting a potential application in UV photodetection.

We describe the preparation and properties of a coaxial, three-layer, gold-CdSe-gold nanowire 30 μm in length that functions as a monolithic photodetector. The gold (Au) electrode core of this sandwich structure is prepared using the lithographically patterned nanowire electrodeposition (LPNE) method on a glass surface. A CdSe shell of defined thickness, dCdSe, from 200 to 280 nm is then electrodeposited on this Au nanowire. Finally, a conformal gold layer is electrodeposited on top of the CdSe shell. The two concentric gold electrodes within this architecture measure the photoconductivity of the ultrathin CdSe absorbing layer in the direction orthogonal to the nanowire axis. This architecture enables accelerated response/recovery of the nanowire to light while simultaneously maximizing the photoconductive gain without relinquishing any of the photoresponsive area of a "bare" nanowire. Characterization by scanning electron microscopy (SEM) of focused ion beam (FIB) cross sections together with electron dispersive X-ray spectroscopy (EDS) reveal the distinct core-multishell nanostructure, layer thicknesses, and layer compositions. The position-dependent photoresponse along the axis of the nanowire, probed using a laser spot, shows that the Au nanoshell significantly enhances the photocurrent. The performance of Au-CdSe-Au core-multishell nanowire photodetectors depend sensitively on the thickness of CdSe nanoshell over the range of from 200 nm < dCdSe < 280 nm. The highest performance was obtained for the dCdSe = 250 nm this device, which showed a photoconductive gain of 2172, a responsivity of 209 A·W(-1), a response time of 17 μs, and a recovery time of 96 μs.

TiO 2 Thin films were deposited by RF magnetron sputtering on silicon dioxide substrates and irradiated using a KrF excimer laser. The effect of laser energy on the film has been systemically investigated by X-ray diffractometry, Raman spectral, X-ray photoelectron spectroscopy, and scanning electron microscopy. When the laser fluence was not higher than 0.3 J/cm 2 , an obvious thermal effect of laser irradiation was observed. And with the laser fluence increasing to 1 J/cm 2 , novel TiO 2 nano-platelets were found on the surface because the laser induced plasma caused electron–ion emission from the TiO 2 film surface. By increasing the laser fluence continually, the nano-platelets become sparse, which was due to the ion density in the plasma induced by laser.

Rice straws are widely used in Daqu (starter) preparation for Maotai-flavour liquor brewing to provide adequate thermal insulation, water retention and aeration. As the straws have direct contact with the Daqu during its preparation, the microorganisms carried by the straws can be transferred to the Daqu. In this study, yellow pigment-producing strains were isolated from the rice straws using a dilution plate method. Most of these strains were characterized as toxoflavin-producing Burkholderia spp. by 16S rRNA sequencing, toxA gene-specific PCR and toxoflavin detection. The PCR assays revealed the existence of Burkholderia in the Daqu samples. The toxoflavin content in a number of Daqu samples was determined using HPLC. The highest observed content of toxoflavin in the Daqu was >8 mg/kg, close to its LD50. Although no toxoflavin was detected in the distilled liquor, the safety problem regarding the use of rice straws in Daqu preparation is still noteworthy, since Burkholderia and toxoflavin can be transferred and can accumulate during the brewing process. The results can contribute to a further assessment of the contamination risk in liquor brewing caused by Burkholderia and to safer production in this traditional process. Copyright © 2015 The Institute of Brewing & Distilling

Syntrophomonadaceae was previously identified to be the predominant bacteria in Chinese Luzhou-flavour liquor pit mud. In this work, a real-time quantitative PCR assay was first employed to monitor the variation of the family Syntrophomonadaceae in the pit mud. The specific primers SynF and SynR were designed based on the 16S rDNA gene. A single specific fragment of about 161 bp was amplified in each positive sample, while no signal or a high cycle threshold (Cq) value (>36) was detected in the negative controls. The correlation coefficient (R2) and amplification efficiency (E) of the standard curve were 0.9997 and 106%, respectively. In addition, the sensitivity was 6.0 × 102 copies/μL and the mean recovery rate was 103%. All of these results indicate that the method is rapid, specific, sensitive and accurate. The quantitative results provide further understanding of the time differences and spatial differences in the family Syntrophomonadaceae in pit mud. Copyright © 2015 The Institute of Brewing & Distilling