Hierarchical amphiphilic high-efficiency oil–water separation membranes from fermentation derived cellulose and recycled polystyrene

A high-efficiency separation of oil and water can be achieved by using specially designed amphiphilic porous membrane. However, the preparation of such membranes often involves complex multistep chemical processes. Herein, we report an amphiphilic composite membrane (polystyrene [PS]/bacterial cellulose [BC] membrane) consisting of hydrophobic recycled PS and hydrophilic BC, fabricated by a facile in situ fermentation process. Not only these membranes exhibit a combination of contrasting wettability but also comprise of a hierarchical network of microfibers and nanofibers, which makes them ideal for oil–water separation. The structural and morphological properties of as-produced BC, recycled PS membrane, and PS/BC composite membrane were studied by Fourier transform infrared spectroscopy and scanning electron microscopy, respectively. The ability of the membranes to separate oil and water was tested by using an emulsion of hexane-in-water as the feed and the collected filtrates were characterized by optical microscopy and UV–Vis spectroscopy. PS membranes were unable to separate oil and water, while the PS/BC membrane efficiently separated water from the emulsion. PS/BC composite membranes showed a high water recovery of more than 90%, against only 57% recovery shown by BC. Mechanisms of oil–water separation for each membrane are discussed. The reusability of the PS/BC composite membrane was also demonstrated.     

Molecular-hydrodynamic study of poly(<Emphasis Type="Italic">N</Emphasis>-methyl-<Emphasis Type="Italic">N</Emphasis>-vinylacetamide) macromolecules

High-velocity sedimentation, translational isothermal diffusion, and viscometry in H₂O and DMF are used to investigate the samples and fractions of poly(N-methyl-N-vinylacetamide) synthesized by free-radical polymerization and fractionated in a chloroform-diethyl ether system. Molecular masses M and the Mark-Kuhn-Houwink-Sakurada relations are obtained for the fractions in the molecular mass range M × 10⁻³ = 3.5−540.0. The negative temperature coefficient of intrinsic viscosity is revealed for both solvents. The length of the Kuhn statistical segment and the hydrodynamic diameter of poly(N-methyl-N-vinylacetamide) macromolecules are estimated; the hydrodynamic volumes occupied by water-soluble poly(N-methyl-N-vinylacetamide), poly(1-vinyl-2-pyrrolidone), poly(vinylformamide), and pullulan molecules are compared.     

薄膜太阳电池的发展值得重视

根据当前光伏市场的迅速发展,要求人们寻找一种高效率低成本的适合规模化生产的太阳电池。作者认为,薄膜太阳电池具有优良的特性,是一种很有发展前途的低成本太阳电池。美、日、欧正在迅速成功地开展薄膜太阳电池的研究与开发,而中国在该项技术上还处于实验室研究阶段,应加快向企业化过渡。     

Restoration of the graphite memory of a reactor in the third power-generating unit of the Leningrad nuclear power plant

The restoration of the graphite masonry of cell 52-16 in the reactor in the third power-generating unit of the Leningrad nuclear power plant is described. The process reduces to moving graphite blocks and columns from adjacent cells into the damaged cell, from which defective blocks are removed beforehand. The columns are moved in a manner so that the empty cell ends up in the region of the steam-gas exhaust passage through the upper metal structure of the reactor unit. The missing blocks are placed in the reactor through the passage. Organizational-technical and radiation questions concerning the work performed are described. 6 figures. Leningrad Nuclear Power Plant. Translated from Atomnaya énergiya, Vol. 87, No. 5, pp. 356–359, November, 1999.     

Comparison of III–V Heterostructures Grown on Ge/Si,Ge/SOI,and GaAs

Semiconductors - III–V/Ge/Si(001), III–V/Ge/SOI(001), and III–V/GaAs(001) heterostructures are fabricated and investigated. The Ge buffer layer for the III–V/Ge/Si structure...     

A 3.8 GHz 153 Mb SRAM Design With Dynamic Stability Enhancement and Leakage Reduction in 45 nm High-k Metal Gate CMOS Technology

A high-performance low-power 153 Mb SRAM is developed in 45 nm high-k Metal Gate technology. Dynamic SRAM PMOS forward-body-bias (FBB) and Active-Controlled SRAM VCC in Sleep are integrated in the design to lower Active-VCCmin and Standby Leakage, respectively. FBB improves the Active-VCCmin by up to 75 mV, and Active-Controlled SRAM VCC distribution tightened by 100 mV, both of which result in further power reduction. A 0.346 mum² 6T-SRAM bit-cell is used which is optimized for VCCmin, performance, leakage and area. The design operates at high-speed over a wide voltage range, and has a maximum frequency of 3.8 GHz at 1.1 V. The 16 KB Subarray was also used as the building block in on-die 6 MB Cache for Intel Core 2 Duo CPU in 45 nm technology.