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Purposefully designing the well-defined catalysts for the selective electroreduction of CO2 to C2 H4 is an extremely important but challenging work. In this work, three crystalline trinuclear copper clusters (Cu3 -X, X=Cl- , Br- , NO3- ) have been designed, containing three active Cu sites with the identical coordination environment and appropriate spatial distance, delivering high selectivity for the electrocatalytic reduction of CO2 to C2 H4 . The highest faradaic efficiency of Cu3 -X for CO2 -to-C2 H4 conversion can be adjusted from 31.90 % to 55.01 % by simply replacing the counter anions (NO3- , Cl- , Br- ). The DFT calculation results verify that Cu3 -X can facilitate the C-C coupling of identical *CHO intermediates, subsequently forming molecular symmetrical C2 H4 product. This work provides an important molecular model system and a new design perspective for electroreduction of CO2 to C2 products with symmetrical molecular structure.

A series of Li–CO2 battery cathode materials are reported based on metal–organic frameworks with dual-metal sites containing a metalloporphyrin and a metal-coordinated pyrazole. MnTPzP-Mn demonstrates a low voltage hysteresis of 1.05 V at 100 mA g−1 and good stability of 90 cycles at 200 mA g−1. Among them, the Mn-coordinated pyrazole site can promote the effective decomposition of Li2CO3, and the Mn-metalloporphyrin site contributes to the activation of CO2. This is the first example of using a crystalline cathode material with a well-defined structure to reveal natural catalytic sites for CO2 reduction/evolution reactions under aprotic conditions in Li–CO2 batteries.

Purposefully designing the well-defined catalysts for the selective electroreduction of CO

A series of Li-CO2 battery cathode materials are reported based on metal-organic frameworks with dual-metal sites containing a metalloporphyrin and a metal-coordinated pyrazole. MnTPzP-Mn demonstrates a low voltage hysteresis of 1.05 V at 100 mA g-1 and good stability of 90 cycles at 200 mA g-1. Among them, the Mn-coordinated pyrazole site can promote the effective decomposition of Li2CO3, and the Mn-metalloporphyrin site contributes to the activation of CO2. This is the first example of using a crystalline cathode material with a well-defined structure to reveal natural catalytic sites for CO2 reduction/evolution reactions under aprotic conditions in Li-CO2 batteries.

Leucine dehydrogenase (LDH) is a NAD+-dependent oxidoreductase, which can selectively catalyze α-keto acids to obtain α-amino acids and their derivatives. It plays a key role in the biosynthesis of L-tert-leucine (L-Tle). As a non-naturally chiral amino acid, L-Tle can be used as an animal feed additive, nutrition fortifier, which is a perspective and important building block in the pharmaceutical, cosmetic, and food additive industry. In this study, four hypothetical leucine dehydrogenases were discovered by using genome mining technology, using the highly active leucine dehydrogenase LsLeuDH as a probe. These four leucine dehydrogenases were expressed in Escherichia coli BL21(DE3), respectively, and purified to homogeneity and characterized. Compared with the other enzymes, the specific activity of PfLeuDH also shows stronger advantage. In addition, the highly selective biosynthesis of L-Tle from trimethylpyruvic acid (TMP) was successfully carried out by whole-cell catalysis using engineered E. coli cells as biocatalyst, which can efficiently coexpress leucine dehydrogenase and formate dehydrogenase. One hundred-millimolar TMP was catalyzed for 25 h, and the yield and space-time yield of L-Tle reached 87.38% (e.e. >99.99%) and 10.90 g L–1 day–1. In short, this research has initially achieved the biosynthesis of L-Tle, laying a solid foundation for the realization of low-cost and large-scale biosynthesis of L-Tle., Graphical Abstract Genome mining of Leucine dehydrogenase and one-pot synthesis of L-tert-leucine from trimethylpyruvic acid.

Formate dehydrogenase (FDH) is a d -2‑hydroxy acid dehydrogenase, and catalyzes the oxidation of formate to carbon dioxide, coupled with reduction of NAD+ to NADH that plays a key role in the process of NADH regeneration. In order to obtain high activity formate dehydrogenase mutants, the formate dehydrogenase CbFDHC23S was used as the parent to conduct two rounds of directed evolution, and a mutant M2 was obtained which specific activity was about 4 times more than the parent and was more suitable for coenzyme regeneration under physiological conditions. Then, the molecular mechanism of temperature characteristic and catalytic efficiency change was preliminarily elucidated by computer-aided method. Finally, an engineered E. coli strain was established to co-express formate dehydrogenase and l -leucine dehydrogenase and enantioselectively transform phenylglyoxylic acid to give l - phenylglycine (e.e. >99%), the yield and space-time yield of l - phenylglycine can reach 90.46% and 82.07 g·L−1·d−1. This study laid a theoretical foundation for the green biosynthesis of food additives such as chiral alcohols and amino acid derivatives catalyzed by FDH coupling to enhance the regeneration capacity of NADH, reduce the regeneration cost of NADH, and achieve high efficiency and low cost.

The enzyme Δ3,Δ2-dienoyl-CoA isomerase (ECI1) plays a crucial role in the mitochondrial β-oxidation of fatty acids with a double-bond in odd and even positions. The ECI1 gene might be a qualified candidate for studies pertaining to lipid deposition and meat quality in swine. In the present study, ECI1 cDNA of the Tibetan pig was obtained by in silico cloning and verified by PCR analysis. Single-nucleotide polymorphisms (SNPs) of ECI1 were screened by PCR-sequencing and genotypes of those SNPs were tested by PCR-restriction fragment length polymorphism (PCR-RFLP) in Diannan small-ear pigs (DSP, n=40), Tibetan pigs (TP, n=60) and Yorkshire pigs (YP, n=30). The expression levels of ECI1 were analyzed by real-time quantitative PCR and Western blotting in tissues of the liver, backfat, and longissimus dorsi (LD) muscle of DSP (n=8), TP (n=8) and YP (n=8). Single factor linear correlation analysis was applied separately for each breed to evaluate correlations between ECI1 gene expression in the LD muscle and intramuscular fat (IMF) content. We obtained an ECI1 gene length of 1 401 bp from the cDNA that contained a full coding region of 909 bp. Three novel SNPs (g.42425337G>A; g.42424666A>G; and g.42422755A>G) were detected, and only g.42424666A>G exhibited three genotypes among the three breeds. The ECI1 expression levels in the LD muscle of DSP and TP were significantly higher than that of YP (P

The hydraulic driven chain saw is a cutting tool for underwater operation. The hydraulic driven chain saw was designed, the hydraulic adjusting device was designed, the hydraulic chain saw experimental platform was designed, the sawing efficiency and power consumption experiments were carried out, and the diamond saw chain wear experiment was carried out. The experimental results show that:When cutting C25 standard reinforced concrete floor plate, the tension of tight edge of diamond saw chain is large; the dynamic load of diamond saw chain has the greatest influence on the tension of diamond saw chain, and the dynamic load is proportional to the rotation speed of chain wheel, the pitch of diamond saw chain, the weight per meter of diamond saw chain and the length of tight edge, among which the rotation speed of chain wheel has an effect on it The noise is the largest; the power consumption of cutting concrete is 2.85kw, the efficiency of sawing concrete is 0.93m2/h, and the sawing area of diamond saw chain per meter is 16.7m2/m.

Phoebe chekiangensis, as one original species of 'Nanmu with golden tint', harbors limited natural distribution regions, which is recognized as a vulnerable species in China under nationwide protection. Under the background of global climate change, it is of scientific significance to study the community structure and diversity of the natural populations of P. chekiangensis. In this study, community structure, species diversity and the phenotypic variation leaf traits in the communities of thirteen residue natural populations were analyzed. A total of 235 vascular species from 162 genera and 87 families were found in 16 plots within 13 natural populations, including 221 seed plants from 151 genera and 79 families. The species diversity in tree layer of community in Kaihua, Zhejiang and Linan, Zhejiang was significantly lower than that of other communities due to severe disturbance, while intermediate disturbance promoted the species diversity of shrub layer in community in Jianning, Fujian, and slight disturbance was beneficial to natural regeneration of P. chekiangensis. Foliage phenotype was important for species identification within Phoebe genus. There existed substantial variation in foliage phenotypic diversity among and within populations. The mean coefficient of variation was 17.2%, ranging from 10.4% to 27.5%. The variation was greater among populations (53.6%) than within populations (17.0%). Mean phenotypic differentiation coefficient was 75.1% among populations, indicating that the variance among populations was the main source for the phenotypic variation of the species. Results from the cluster analysis indicated that the 13 natural populations were divided into two distinct groups based on the Euclidean distance (10 cm), with stochastic variation.浙江楠为商品材“金丝楠木”的原植物之一,天然分布区窄,属国家二级保护渐危种,在全球气候变化背景下,研究其天然种群所在森林群落的结构特征及其多样性具有重要意义.本研究以浙江楠天然分布区内13个典型种群为对象,研究其所在群落的群落结构特征、物种多样性和叶片表型变异特征.结果表明: 浙江楠天然种群所在群落的结构复杂,物种多样性较高,13个群落的16块样地内共有维管束植物87科162属235种,其中种子植物79科151属221种;重度干扰导致浙江开化、浙江临安等群落的乔木层物种多样性指数显著低于其他群落,而中度干扰提高了福建建宁群落灌木层物种多样性,轻度干扰则利于浙江楠种群自然更新.叶片表型作为楠木属植物重要的分类依据,叶片表型性状在种群间、种群内均存在丰富变异,平均变异系数为17.2%,变异幅度为10.4%～27.5%.种群间的变异(53.6%)大于种群内的变异(17.0%),平均表型分化系数为75.1%,种群间变异是浙江楠叶片表型变异的主要来源.基于欧式距离(10 cm)将13个天然种群划分为两大类群,但变异呈随机性.

Three strains representing a novel species of yeast were isolated from samples of rotting wood collected from Xishuangbanna Tropical Rainforest in Yunnan Province, PR China. Phylogenetic analysis based on the concatenated sequences of the internal transcribed spacer (ITS) region and the D1/D2 domains of the large subunit (LSU) rRNA gene revealed that the novel species is a member of the genus Cyberlindnera, although the formation of ascospores was not observed. The novel species was related most closely to the type strain of the species Candida pattaniensis, but they had a 0.5 % sequence divergence (3 substitutions, 0 gap) in the D1/D2 domain and a 5.4 % sequence divergence (21 substitutions, 10 gaps) in the ITS region. The novel species could also be differentiated from the closely related species by some biochemical and physiological characteristics. The species name Cyberlindnera xishuangbannaensis f.a., sp. nov. is proposed to accommodate these strains, with NYNU 16752T (=CICC 33163T=CBS 14692T) designated as the type strain. The MycoBank number is MB 822199.

Four yeast strains were isolated from rotting wood samples collected in the Baotianman Nature Reserve in Henan Province, central China. The sequences of the D1/D2 domains of the large subunit rRNA gene and the internal transcribed spacer regions showed that these four strains represent two different undescribed yeast species belonging to the Ogataea clade. Ogataea neixiangensis sp. nov. produces two to four hat-shaped ascospores per ascus, and its closest relative among recognized species is Candida nitratophila. Ogataea paraovalis f.a., sp. nov. is closely related to Candida ovalis but the formation of ascospores was not observed on various sporulation media. The type strain of O. neixiangensis sp. nov. (MycoBank number MB 820697) is NYNU 16951T (=CICC 33166T=CBS 14695T), and the type strain of O. paraovalis f.a., sp. nov. (MycoBank number MB 820698) is NYNU 167106T (=CICC 33168T=CBS 14697T).

Maintenance and management of genetic diversity of farm animal genetic resources (AnGR) is very important for biological, socioeconomical and cultural significance. The core concern of conservation for farm AnGR is the retention of genetic diversity of conserved populations in a long-term perspective. However, numerous factors may affect evolution of genetic diversity of a conserved population. Among those factors, the genetic architecture of conserved populations is little considered in current conservation strategies. In this study, we investigated the dynamic changes of genetic diversity of conserved populations with two scenarios on initial genetic architectures by computer simulation in which thirty polymorphic microsatellite loci were chosen to represent genetic architecture of the populations with observed heterozygosity (Ho) and expected heterozygosity (He), observed and mean effective number of alleles (Ao and Ae), number of polymorphic loci (NP) and the percentage of polymorphic loci (PP), number of rare alleles (RA) and number of non-rich polymorphic loci (NRP) as the estimates of genetic diversity. The two scenarios on genetic architecture were taken into account, namely, one conserved population with same allele frequency (AS) and another one with actual allele frequency (AA). The results showed that the magnitude of loss of genetic diversity is associated with genetic architecture of initial conserved population, the amplitude of genetic diversity decline in the context AS was more narrow extent than those in context AA, the ranges of decline of Ho and Ao were about 4 and 2 times in AA compared with that in AS, respectively, the occurrence of first monomorphic locus and the time of change of measure NP in scenario AA is 20 generations and 23 generations earlier than that in scenario AS, respectively. Additionally, we found that NRP, a novel measure proposed by our research group, was a proper estimate for monitoring the evolution of genetic diversity in a closed conserved population. Our study suggested that current managements of conserved populations should emphasize on initial genetic architecture in order to make an effective and feasible conservation scheme.

In the semiarid area, the structural nature of sandy land is changed due to wind erosion. Furthermore, assessing the changes in the composition and surface roughness in several spatial and temporal scales is significant for the wind erosion model calculations. As a noninvasive approach, remote sensing can be used to improve the study of sandy surface in time and space. In order to characterize the surface structure using the reflectance of sandy land, we analysis the effects of the changes of sandy surface structure on the bidirectional reflectance distribution basing on the multi-angular and hyperspectral measurements in the field; the measured sandy land samples are taken from nature, but the surface structures are artificial: one type is the direction of sand furrows is parallel to the incident direction, the other is the direction of sand furrows is perpendicular to the incident direction. At the same time, we analyzed the effects of surface structure on the bidirectional reflectance factor of sand land and we also retrieve the sandy surface roughness using the reflectance model parameter. The results suggest that both types of sand furrows will influence the distribution of reflectance of sandy land surface, for example, the backward scattering of sandy land increased when the direction of sand furrows is perpendicular to the incident direction, and the range of backward scattering of sandy land expended when the direction of sand furrows is parallel to the incident direction. When we compared the measured reflectance with the modeled results basing on the reflectance model, it is found that the reflectance model can be used to simulate the reflectance property of sandy land surface and prove that the parameter of model is useful for retrieving the surface roughness. This research not only presents the sample for quantifying the structural information of sandy land by the reflectance measurements, but also shows valuable reference for the research of intrinsic optical property of sandy land and the reversion of the texture of sandy land. In other words, this paper can also help the scientists understand the effect of the structural information on the optical properties of sandy land.

In this paper we present the cold extrusion shaping technology of 20Cr bevel gears. First, we analyzed a series of processing and treatment referring to bevel gear cold extrusion technology and calculated the cold extrusion pressures used for mold design; then, we designed and cold extruded two- or three-ring composite cold extrusion dies with its precise guiding device; and last, we experimentally tested our designed and extruded bevel gear. The results showed that 20Cr bevel gears shaped with cold extrusion have qualified properties and satisfy application requirements within the required error range. This research is of significance in actual cold extrusion production.

Software testing is becoming a relatively independent activity of software development process. To estimate the cost of software testing is an important part of project management. The researchers have focused on the software cost and treated software testing cost as a part of the total software development cost for several years. Few researchers consider software testing as a separate process to estimate its’ cost. This paper proposed a new constructive cost model for software testing project management (CCMST) which contains the main cost divers of software testing. The cost drivers included in this model is more comprehensive than former models. Application case study proved the model is usable and valid.

Titanium dioxide (TiO(2)) thin film was deposited on the surface of the light addressable potentiometric sensor (LAPS) to modify the sensor surface for the non-labeled detection of DNA molecules. To evaluate the effect of ultraviolet (UV) treatment on the silanization level of TiO(2) thin film by 3-aminopropyltriethoxysilane (APTS), fluorescein isothiocyanate (FITC) was used to label the amine group on the end of APTS immobilized onto the TiO(2) thin film. We found that, with UV irradiation, the silanization level of the irradiated area of the TiO(2) film was improved compared with the non-irradiated area under well-controlled conditions. This result indicates that TiO(2) can act as a coating material on the biosensor surface to improve the effect and efficiency of the covalent immobilization of biomolecules on the sensor surface. The artificially synthesized probe DNA molecules were covalently linked onto the surface of TiO(2) film. The hybridization of probe DNA and target DNA was monitored by the recording of I-V curves that shift along the voltage axis during the process of reaction. A significant LAPS signal can be detected at 10 micromol/L of target DNA sample.