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71.
Roads are a prominent feature of many landscapes, and high road densities create correspondingly high ecological impacts by altering landscape patterns, interrupting ecological flows, increasing erosion, fragmenting habitat, and facilitating the spread of invasive species. Here, we describe the construction of “near-natural greenways” that produce environmentally and socially harmonious road systems that meet the needs of both the environment and the socioeconomic development in China and that satisfy environmental, ecological, educational, traffic safety, economic, and sustainable developmental goals. In the last decade, China has embarked upon the implementation of a network of near-natural greenways with the vision of linking economic development with nature conservation by means of improved rehabilitation of existing road systems and improved construction of new roads. Ecological science, and especially landscape ecology, will play an important role in the planning and implementation of future near-natural greenways in China and around the world.  相似文献   
72.
73.
To develop a durable proton‐exchange membrane (PEM) for fuel‐cell applications, a series of sulfonated poly(benzoxazole thioether sulfone)s ( SPTESBOs) are designed and synthesized, with anticipated good dimensional stability (via acid–base cross linking), improved oxidative stability against free radicals (via incorporation of thioether groups), and enhanced inherent stability (via elimination of unstable end groups) of the backbone. The structures and the degree of sulfonation of the copolymers are characterized using Fourier‐transform infrared spectroscopy, and nuclear magnetic resonance spectroscopy (1H NMR and 19F NMR). The electrochemical stabilities of the monomers are examined using cyclic voltammetry in a typical three‐electrode cell configuration. The physicochemical properties of the membranes vital to fuel‐cell performance are also carefully evaluated under conditions relevant to fuel‐cell operation, including chemical and thermal stability, proton conductivity, solubility in different solvents, water uptake, and swelling ratio. The new membranes exhibit low dimensional change at 25°C to 90°C and excellent thermal stability up to 250°C. Upon elimination of unstable end groups, the co‐polymers display enhanced chemical resistance and oxidative stability in Fenton's test. Further, the SPTESBO‐HFB‐60 (HFB‐60=hexafluorobenzene, 60 mol% sulfone) membrane displays comparable fuel‐cell performance to that of an NRE 212 membrane at 80°C under fully humidified condition, suggesting that the new membranes have the potential to be more durable but less expensive for fuel‐cell applications.  相似文献   
74.
炭疽芽胞杆菌(Bacillus anthracis)检测质粒的构建及其应用   总被引:1,自引:0,他引:1  
根据炭疽芽胞杆菌(Bacillus anthracis)毒性质粒pX01和pX02上的2个毒力相关基因cya和capA的序列特点,以pIJ2925为出发载体,采用一步重叠延伸PCR技术(One-step Overlap Extension PCR,简称OOE-PCR)构建了包含cya基因和capA基因保守区DNA片段的炭疽检测质粒pBIB2006。采用复合PCR对模拟炭疽危险品进行分析,结果表明pBIB2006可以为炭疽芽胞杆菌的检测提供准确、安全和方便的阳性参照品,从而为检测炭疽芽胞杆菌和炭疽芽胞杆菌灭活疫苗提供了便利。  相似文献   
75.
Endometriosis affects younger women of childbearing age. Atherosclerosis is considered as a disease of the old and increases with the ageing process. Both diseases are characterized by the increased presence of activated macrophages and associated increases in growth promoting activity and the production of inflammatory cytokines. In this review, we propose that oxidative stress and the presence of forms of oxidized low-density lipoprotein (LDL) might contribute to both Atherosclerosis and Endometriosis.  相似文献   
76.
Achieving high-performance in all-small-molecule organic solar cells (ASM-OSCs) significantly relies on precise nanoscale phase separation through domain size manipulation in the active layer. Nonetheless, for ASM-OSC systems, forging a clear connection between the tuning of domain size and the intricacies of phase separation proves to be a formidable challenge. This study investigates the intricate interplay between domain size adjustment and the creation of optimal phase separation morphology, crucial for ASM-OSCs’ performance. It is demonstrated that exceptional phase separation in ASM-OSCs’ active layer is achieved by meticulously controlling the continuity and uniformity of domains via re-packing process. A series of halogen-substituted solvents (Fluorobenzene, Chlorobenzene, Bromobenzene, and Iodobenzene) is adopted to tune the re-packing kinetics, the ASM-OSCs treated with CB exhibited an impressive 16.2% power conversion efficiency (PCE). The PCE enhancement can be attributed to the gradual crystallization process, promoting a smoothly interconnected and uniformly distributed domain size. This, in turn, leads to a favorable phase separation morphology, enhanced charge transfer, extended carrier lifetime, and consequently, reduced recombination of free charges. The findings emphasize the pivotal role of re-packing kinetics in achieving optimal phase separation in ASM-OSCs, offering valuable insights for designing high-performance ASM-OSCs fabrication strategies.  相似文献   
77.
Developing a titanium dioxide (TiO2)‐based anode with superior high‐rate capability and long‐term cycling stability is important for efficient energy storage. Herein, a simple one‐step approach for fabricating blue TiO2 nanoparticles with oxygen vacancies is reported. Oxygen vacancies can enlarge lattice spaces, lower charge transfer resistance, and provide more active sites in TiO2 lattices. As a result, this blue TiO2 electrode exhibits a highly reversible capacity of 50 mAh g?1 at 100 C (16 800 mA g?1) even after 10 000 cycles, which is attributable to the combination of surface capacitive process and remarkable diffusion‐controlled insertion revealed by the kinetic analysis. The strategy of employing oxygen‐deficient nanoparticles may be extended to the design of other robust semiconductor materials as electrodes for energy storage.  相似文献   
78.
Förster resonance energy transfer (FRET) technology has been widely used in biological and biomedical research, and it is a very powerful tool for elucidating protein interactions in either dynamic or steady state. SUMOylation (the process of SUMO [small ubiquitin-like modifier] conjugation to substrates) is an important posttranslational protein modification with critical roles in multiple biological processes. Conjugating SUMO to substrates requires an enzymatic cascade. Sentrin/SUMO-specific proteases (SENPs) act as an endopeptidase to process the pre-SUMO or as an isopeptidase to deconjugate SUMO from its substrate. To fully understand the roles of SENPs in the SUMOylation cycle, it is critical to understand their kinetics. Here, we report a novel development of a quantitative FRET-based protease assay for SENP1 kinetic parameter determination. The assay is based on the quantitative analysis of the FRET signal from the total fluorescent signal at acceptor emission wavelength, which consists of three components: donor (CyPet–SUMO1) emission, acceptor (YPet) emission, and FRET signal during the digestion process. Subsequently, we developed novel theoretical and experimental procedures to determine the kinetic parameters, kcat, KM, and catalytic efficiency (kcat/KM) of catalytic domain SENP1 toward pre-SUMO1. Importantly, the general principles of this quantitative FRET-based protease kinetic determination can be applied to other proteases.  相似文献   
79.

Key message

BcMF11 as a non-coding RNA gene has an essential role in pollen development, and might be useful for regulating the pollen fertility of crops by antisense RNA technology.

Abstract

We previously identified a 828-bp full-length cDNA of BcMF11, a novel pollen-specific non-coding mRNA-like gene from Chinese cabbage (Brassica campestris L. ssp. chinensis Makino). However, little information is known about the function of BcMF11 in pollen development. To investigate its exact biological roles in pollen development, the BcMF11 cDNA was antisense inhibited in transgenic Chinese cabbage under the control of a tapetum-specific promoter BcA9 and a constitutive promoter CaMV 35S. Antisense RNA transgenic plants displayed decreasing expression of BcMF11 and showed distinct morphological defects. Pollen germination test in vitro and in vivo of the transgenic plants suggested that inhibition of BcMF11 decreased pollen germination efficiency and delayed the pollen tubes’ extension in the style. Under scanning electron microscopy, many shrunken and collapsed pollen grains were detected in the antisense BcMF11 transgenic Chinese cabbage. Further cytological observation revealed abnormal pollen development process in transgenic plants, including delayed degradation of tapetum, asynchronous separation of microspore, and aborted development of pollen grain. These results suggest that BcMF11, as a non-coding RNA, plays an essential role in pollen development and male fertility.  相似文献   
80.
Monoclonal antibodies constitute a robust class of therapeutic proteins. Their stability, resistance to stress conditions and high solubility have allowed the successful development and commercialization of over 40 antibody-based drugs. Although mAbs enjoy a relatively high probability of success compared with other therapeutic proteins, examples of projects that are suspended due to the instability of the molecule are not uncommon. Developability assessment studies have therefore been devised to identify early during process development problems associated with stability, solubility that is insufficient to meet expected dosing or sensitivity to stress. This set of experiments includes short-term stability studies at 2−8 þC, 25 þC and 40 þC, freeze-thaw studies, limited forced degradation studies and determination of the viscosity of high concentration samples. We present here three case studies reflecting three typical outcomes: (1) no major or unexpected degradation is found and the study results are used to inform early identification of degradation pathways and potential critical quality attributes within the Quality by Design framework defined by US Food and Drug Administration guidance documents; (2) identification of specific degradation pathway(s) that do not affect potency of the molecule, with subsequent definition of proper process control and formulation strategies; and (3) identification of degradation that affects potency, resulting in program termination and reallocation of resources.  相似文献   
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