摘要：1,3-propanediol (1,3-PD) is an important material for chemical industry,and there has been always much interest in the production of 1,3-PD using all possible routes. The genes encoding glyc-erol dehydratase (GDHt) from Citrobacter freundii,Klebsiella pneumoniae and metagenome were cloned and expressed in E. coli. All glycerol dehy-dratases but the one from metagenome could be detected to show enzyme activities. In order to im-prove the enzymatic properties of GDHts,the genes encoding α and β-γ subunits were cloned,and the enzyme characteristics were evolved by rational de-sign based on their 3D structures which were con-structed by homology modeling. Six heteroenzymes were obtained by swapping the α subunit genes of these three different-source-derived GDHts. The pH,thermal stability and Vmax of some heteroenzymes were dramatically improved by 2―5 times compared with the wild one (GDHtKP). The GDHt cloned from metagenome,originally proved to be with no enzyme activity,was converted into active enzyme by swap-ping its subunits with other different GDHts. In addi-tion,the effect of subtle 3D structural changes on the properties of the enzyme was also observed.

摘要：Aims Bee-pollinated flowers are rarely red,presumably because bees(which lack red receptors)have difficulty detecting red *** the response of bees to red colour has been investigated in lab experiments,most stimuli have been pure red,while the subtle diversity of red as perceived by humans(human-red)has received very limited *** we test the hypothesis that ultraviolet(UV)reflected from human-red flowers enhances their attractiveness to bees,through increased chromatic *** Using Onosma confertum(Boraginaceae),a plant with UV-reflecting red flowers that are pollinated by bumblebees,we investigated the effects of UV reflection on pollinator responses by conducting phenotypic manipulation experiments in the *** preferences of flower-naïve bumblebees were also *** perception by bumblebees was estimated in terms of chromatic and achromatic contrast,based on two different colour perception *** Findings We found that both natural and flower-naïve bumblebees strongly preferred visiting UV-reflecting targets compared with UV-absorbing *** models show that the UV-reflecting flowers exhibit higher spectral purity and higher chromatic contrast against the foliage background,whereas they have similar achromatic contrast in terms of green receptor *** results indicate that the component of UV reflection increases chromatic contrast in ***,enhancing the visual attractiveness of these red flowers to *** further infer that the secondary reflectance might be a necessary component in human-red flowers that are primarily pollinated by animals without red receptors,such as bees.

摘要：The solar spectrum covers a broad wavelength range, which requires that antireflection coating （ARC） is effective over a relatively wide wavelength range for more incident light coming into the cell. In this paper, we present two methods to measure the composite reflection of SiO2/ZnS double-layer ARC in the wavelength ranges of 300-870 nm （duaI- junction） and 300-1850 nm （triple-junction）, under the solar spectrum AM0. In order to give sufficient consideration to the ARC coupled with the window layer and the dispersion effect of the refractive index of each layer, we use multidimensional matrix data for reliable simulation. A comparison between the results obtained from the weighted-average reflectance （WAR） method commonly used and that from the effective-average reflectance （EAR） method introduced here shows that the optimized ARC through minimizing the effective-average reflectance is convenient and available.

摘要：Design and construction of the first prototype ionization chamber for CSNS and Proton Accelerator （PA） beam loss monitor （BLM） system is reported. The low leakage current （〈0.1 pA）, good plateau （≈800 V） and linearity range up to 200 Roentgen/h are obtained in the first prototype. All of these give us good experience for further improving the ionization chamber construction.

摘要：Based on the first ionization chamber （IC） prototype, the structure, working gas component and electrode material of the IC are improved. The test of the improved IC shows that the plateau length is about 2000 V, the plateau slope is less than 0.2%/100 V, the sensitivity is 19.6 pA/rad·h 1, the up-limitation of the linearity can be up to 3.6×105 rad/h, and the applied voltage can be operated to 3500 V. The test results show that the performance of the improved IC meets the requirements of the beam loss monitor.

摘要：Efficacious regulation of the geometric and electronic structures of carbon nanomaterials via the introduction of defects and their synergy is essential to achieving good electrochemical ***,the guidelines for designing hybrid materials with advantageous structures and the fundamental understanding of their electrocatalytic mechanisms remain ***,superfine Pt and PtCu nanoparticles supported by novel S,N‐co‐doped multi‐walled CNT(MWCNTs)were prepared through the innovative pyrolysis of a poly(3,4‐ethylenedioxythiophene)/polyaniline copolymer as a source of S and *** uniform wrapping of the copolymer around the MWCNTs provides a high density of evenly distributed defects on the surface after the pyrolysis treatment,facilitating the uniform distribution of ultrafine Pt and PtCu ***,the Pt_(1)Cu_(2)/SN‐MWCNTs show an obviously larger electroactive surface area and higher mass activity,stability,and CO poisoning resistance in methanol oxidation compared to Pt/SN‐MWCNTs,Pt/S‐MWCNTs,Pt/N‐MWCNTs,and commercial Pt/*** functional theory studies confirm that the co‐doping of S and N considerably deforms the CNTs and polarizes the adjacent C ***,both the adsorption of Pt1Cu2 onto the SN‐MWCNTs and the subsequent adsorption of methanol are enhanced;in addition,the catalytic activity of Pt_(1)Cu_(2)/SN‐MWCNTs for methanol oxidation is thermodynamically and kinetically more favorable than that of its CNT and N‐CNT *** work provides a novel method to fabricate high‐performance fuel cell electrocatalysts with highly dispersed and stable Pt‐based nanoparticles on a carbon substrate.

摘要：Rapid technological development and population growth are responsible for a series of imminent environmental problems and an ineluctable energy *** application of semiconductor nanomaterials in photocatalysis or photoelectrocatalysis(PEC)for either the degradation of contaminants in the environment or the generation of hydrogen as clean fuel is an effective approach to alleviate these ***,the efficiency of such processes remains suboptimal for real *** construction of a built-in electric field is considered to efficiently enhance carrier separation and reduce carrier recombination to improve catalytic *** the past decade,as a new method to enhance the built-in electric field,the piezoelectric effect from piezoelectric materials has been extensively *** this review,we provide an overview of the properties of piezoelectric materials and the mechanisms of piezoelectricity and ferroelectricity for a built-in electric ***,piezoelectric and ferroelectric polarization regulated built-in electric fields that mediate catalysis are ***,the applications of piezoelectric semiconductor materials are also highlighted,including degradation of pollutants,bacteria disinfection,water splitting for H2 generation,and organic *** conclude by discussing the challenges in the field and the exciting opportunities to further improve piezo-catalytic efficiency.

摘要：Along with the unceasing growth of worldwide economic and the associated issues on resources,energy and environment,clean energy generating technologies that are based on recyclable materials,if possible,may become the future trend of ***,we report the design of a cheap,lightweight,and recyclable single-electrode triboelectric nanogenerator(TENG)that utilizes waste paper as the triboelectric *** the current strategy,we successfully developed green energy machines without vastly increasing the mining of various critical minerals around the *** as-designed TENG could not only collect and convert mechanical energy into electricity with sound efficiency,but also has the merit for continuous reuse and quick *** maximum output power density is as high as 171 mW·m^(-2) at a resistance of 130 MQ and could be integrated into a book for monitoring reading actions,thus providing a new approach to the low-cost,green and sustainable self-powered electronic systems.

摘要：As the kinetically sluggish oxygen evolution reaction(OER)is considered to be a bottleneck in overall water splitting,it is necessary to develop a highly active and stable electrocatalyst to overcome this ***,we successfully fabricated a three-dimensional iron-dysprosium oxide co-regulated in-situ formed MOF-Ni arrays on carbon cloth(FeDy@MOF-Ni/CC)through a facile two-step hydrothermal *** studies demonstrate that the designed FeDy@MOF-Ni/CC catalyst requires an overpotential of only 251 mV to reach 10 mA cm-2 with a small Tafel slope of 52.1 mV ***,the stability declined by only 5.5%after 80 h of continuous testing in 1.0 M ***,a cell voltage of only 1.57 V in the overall water splitting system is sufficient to achieve 10 mA cm-2;this value is far better than that of most previously reported *** excellent catalytic performance originates from the unique 3D rhombus-like structure,as well as coupling synergies of Fe-Dy-Ni *** combination of lanthanide and transition metal species in the synthesis strategy may open entirely new possibilities with promising potential in the design of highly active OER electrocatalysts.

摘要：Fundus diagnosis is an important part of the whole body examination that may provide rich clinical information to doctors for diagnostic reference. Manual fundus vessel extraction is helpful to quantitative measurement of diseases but obviously it is a tough work for physicians. This paper presents an automatic method by using Gabor filter bank to extract the artery and vein separately in the ocular fundus images. After preprocessing steps that include gray-scale transform, gray value inversion and contrast enhancement, the Gabor filter bank is applied to the extraction of the artery and vein in the ocular fundus images. Finally these two different width types of vessels are selected by post-processing methods such as labeling, corrosion, binarization, etc. Evaluation results show an accurate rate of 90% in vein and 82% in artery from 20 cases, that indicates the effectiveness of our proposed segmentation method.