2D Enzyme Cascade Network with Efficient Substrate Channeling by Swinging Arms

In living cells, compartmentalized or membrane‐associated enzymes are often assembled into large networks to cooperatively catalyze cascade reaction pathways essential for cellular metabolism. Here, we report the assembly of an artificial 2D enzyme network of two cascade enzymes—glucose‐6‐phosphate dehydrogenase (G6PDH) and lactate dehydrogenase (LDH)—on a wireframe DNA origami template. Swinging arms were used to facilitate the transport of the redox intermediate of NAD⁺/NADH between enzyme pairs on the array. The assemblies of 2D enzyme networks were characterized by gel electrophoresis and visualized by atomic force microscopy (AFM). The spatial arrangements of multiple enzyme pairs were optimized to facilitate efficient substrate channeling by exploiting the programmability of DNA origami to manipulate the key parameters of swinging arm length and stoichiometry. Compared with a single enzyme pair, the 2D organized enzyme systems exhibited higher reaction efficiency due to the promoted transfer of intermediates within the network.     

某水电站古滑坡体滑速涌浪分析

某水电站古滑坡体位于库首右岸的峡谷进口段,总方量约1 327×10~4 m~3,历史上该滑坡体曾多次发生滑动,目前处于临界稳定状态。古滑坡体下游侧边缘距离水电站建筑物较近,水电站扩建过程中施工因素及扩建后水库水位上升对古滑坡体的稳定影响较大,一旦滑坡体再次启动滑入水库,激起的涌浪对该工程威胁较大。基于潘家铮滑速计算方法,对计算式进行改进,编写了Fortran计算程序,运用改进后的潘家铮滑速计算方法分析了该古滑坡体的加速度、速度的变化规律;分别采用潘家铮涌浪计算方法和水科院经验公式预测了滑坡体入库激起对岸涌浪高度和坝址处涌浪高度,研究成果对工程建设具有指导意义。     

袁河新泉乡段梯级溢流堰水动力模拟及侵蚀分析

为了分析梯级溢流堰对袁河新泉乡段河道行洪及河床抗冲的影响,优化河道治理工程中溢流堰布置,建立了将拦河溢流堰作为闭边界条件的二维水动力数值模型,采用非结构化网格的有限体积法,对比分析了十年一遇洪水情况下梯级溢流堰建设前后河道水动力、河道水位、流场沿程变化特征,讨论了溢流堰布置对河道防洪及冲刷的影响。结果表明,在十年一遇洪水情况下溢流堰会抬升河道水位,平均增加0.49 m,满足河道行洪要求;梯级溢流堰使河道整体形成人工“阶梯深潭”体系,河道流速在空间上发生明显的异质性,堰上流速下降幅度较堰下流速大;水流发生急流与缓流之间交替,水流紊动强烈,加剧了水流能量损失,有效降低流速,减轻了河道冲刷,有利于稳定河岸结构。     

Understanding attitudes of hydrogen fuel-cell vehicle adopters in Japan

As of January 2021, Japan had the world's largest hydrogen station network with merely 4600 hydrogen fuel-cell vehicles (HFCVs) on roads, as compared to the 9000 HFCVs in the US, with only one-third of the hydrogen refueling stations in Japan. To understand behavioral differences among Japanese adopters, we administered a survey, in cooperation with public and private sector stakeholders, involving 89 private HFCV adopters in the Aichi Prefectural region, which hosts the largest number of HFCVs and refueling stations in Japan. Results suggest that HFCV adopters have a higher socioeconomic status than non-adopters, are mostly male in their 50s and above, and have a higher interest in new vehicle fuel technology. HFCV adopters who leased and bought vehicles were similar in terms of socioeconomic status, with differences in attitudes toward governmental incentives. The lack of refueling stations and station business hours restrict HFCV adopters from continuing with this fuel technology.     

Combining Electricity and Fuel Supply: Operational Strategies for Biogas Plants

The operational consequences resulting from the combination of a flexibly operated combined heat and power unit (CHP) and an off‐grid biomethane filling station at one biogas plant were investigated. Four different operating scenarios were compared to evaluate the storage capacity needed to balance biogas demand fluctuations and biogas production. The scenario in which fuel production was given priority and electricity was produced within the remaining hours proved to cause the lowest additional costs since it does not require additional installation of biogas storage capacity and causes minor opportunity cost in electricity marketing. Giving fuel demand the priority reduces the necessary biogas storage capacity by 75 % compared to parallel optimization of the electricity and fuel demands.     

加油站油气回收技术的应用

油气回收对于资源综合利用及环境保护具有重大意义。介绍了加油站油气回收的工艺及油气回收性能的检测方法,对油气回收设备的安装进行了说明,并提出了油气回收改造的注意问题及建议。     

形变组织对水电用高强度贝氏体钢再加热奥氏体晶粒长大的影响

对某水电用800 MPa调质贝氏体高强钢进行了热变形-热处理晶粒长大的实验室联合试验。采用Gleeble-3500热力模拟试验机对钢试样进行不同工艺热压缩变形后冷却至室温,随后对试样进行模拟淬火再加热,在900～1200℃不同温度和保温时间条件下奥氏体化,研究热变形组织的差异对重新奥氏体化晶粒长大的影响规律。结果表明,不同应变速率(0.01～10 s^-1)、变形温度(900～1150℃)和60%工程应变下,试验钢获得的变形组织大致可分为3类：带有明显变形特征的组织、均匀细小的完全再结晶组织和已长大粗化的再结晶组织。3类组织再加热过程中其晶粒长大趋势基本相同,起始晶粒尺寸越大则最终奥氏体晶粒尺寸越大;但在950℃等温时,带有明显变形特征组织的变形试样奥氏体晶粒先缓慢长大后又迅速长大粗化。经评估验证,所建立的Sellars模型、Beck模型和Hillert模型晶粒长大动力学方程对于试验钢的奥氏体晶粒长大行为均有比较满意的预测效果。3类变形组织对应的Hillert模型及Sellars模型中奥氏体长大激活能基本相同,说明同一成分钢种的初始组织的差异并未显著影响晶粒长大机制...     

Quantum dot cascade laser

We demonstrated an unambiguous quantum dot cascade laser based on InGaAs/GaAs/InAs/InAlAs heterostructure by making use of self-assembled quantum dots in the Stranski-Krastanow growth mode and two-step strain compensation active region design. The prototype generates stimulated emission at λ ~ 6.15 μm and a broad electroluminescence band with full width at half maximum over 3 μm. The characteristic temperature for the threshold current density within the temperature range of 82 to 162 K is up to 400 K. Moreover, our materials show the strong perpendicular mid-infrared response at about 1,900 cm^-1. These results are very promising for extending the present laser concept to terahertz quantum cascade laser, which would lead to room temperature operation.

PACS

42.55.Px; 78.55.Cr; 78.67.Hc     

水电工程引水隧洞施工安全管理分析

安全管理是一个非常受重视的概念,工程施工中如何做好安全管理必须慎之又慎。引水隧洞是引水式水电站中较为重要的建筑物之一。通常在水电站引水隧洞洞口前设有一道拦水坝,用以保证隧洞施工的安全。结合在小型水电站施工中的实践经验,文章探讨了在引水隧洞施工中如何开展施工安全管理;同时针对如何确保工程顺利、人身财产安全问题提供了解决方案。