Shape-engineerable and highly densely packed single-walled carbon nanotubes and their application as super-capacitor electrodes

We present a rational and general method to fabricate a high-densely packed and aligned single-walled carbon-nanotube (SWNT) material by using the zipping effect of liquids to draw tubes together. This bulk carbon-nanotube material retains the intrinsic properties of individual SWNTs, such as high surface area, flexibility and electrical conductivity. By controlling the fabrication process, it is possible to fabricate a wide range of solids in numerous shapes and structures. This dense SWNT material is advantageous for numerous applications, and here we demonstrate its use as flexible heaters as well as supercapacitor electrodes for compact energy-storage devices.     

Influence of air bubble size on float–sink of spheres in a gas–solid fluidized bed

The float–sink of density adjusted spheres of different diameter (10–40 mm) in a gas–solid fluidized bed was investigated at various bed heights (50–200 mm). The maximum density of floating spheres (ρ_float) and the minimum density of sinking spheres (ρ_sink) were determined by the float–sink experiments. The fluidized bed density (ρ_fb) was measured using the height and cross section of the fluidized bed and total weight of the fluidized media. The diameter of air bubbles at the bed surface was measured at each bed height, and was normalized by the sphere diameter. It was found that the value of ρ_fb–ρ_float approaches zero as the normalized bubble diameter decreases from 4 to 0.5 regardless of the sphere diameter. The value of ρ_sink–ρ_fb for sphere diameter = 10 mm approaches zero as the normalized bubble diameter decreases from 4 to 1.5, whereas the value for sphere diameter = 20–40 mm rises from zero as the normalized bubble diameter decreases from 1.5 to 0.5. The float and sink of spheres basically tend to follow the fluidized bed density with decreasing the normalized bubble diameter. However, relatively larger spheres do not sink based on the density difference as the normalized bubble diameter decreases, which may be due to that the fluidized bed viscosity becomes larger as the normalized bed diameter decreases.     

Anisotropic optical and electronic properties of two-dimensional layered germanium sulfide

Two-dimensional (2D) layered materials,transition-metal dichalcogenides,and black phosphorus have attracted considerable interest from the viewpoints of fundamental physics and device applications.The establishment of new functionalities in anisotropic layered 2D materials is a challenging but rewarding frontier,owing to the remarkable optical properties of these materials and their prospects for new devices.Herein,we report the anisotropic and thicknessdependent optical properties of a 2D layered monochalcogenide of germanium sulfide (GeS).Three Raman-scattering peaks corresponding to the B3g,A1g,and A2g modes with a strong polarization dependence are demonstrated in the GeS flakes,which validates polarized Raman spectroscopy as an effective method for identifying the crystal orientation of anisotropic layered GeS.Photoluminescence (PL) is observed with a peak at ～1.66 eV that originates from the direct optical transition in GeS at room temperature.The polarization-dependent characteristics of the PL,which are revealed for the first time,along with the demonstration of anisotropic absorption,indicate an obvious anisotropic optical transition near the band edge of GeS,which is supported by density functional theory calculations.The significantly thickness-dependent PL is observed and discussed.This anisotropic layered GeS presents opportunities for the discovery of new physical phenomena and will find applications that exploit its anisotropic properties,such as polarization-sensitive photodetectors.     

生物接触氧化预处理水中藻类及其毒素

用生物接触氧化法预处理富营养化太湖原水的研究结果表明，该工艺可有效去除原水中85．90％的细胞外藻毒素和84．0％的总澡毒素，对细胞外Microcystin-RR(M-RR)和Microcys-tin-LR(M-LR)的去除率分别为81．7％和86．7％，对总M－RR和M－LR的去除率分别为80．5％和71．5％，从而可大量节省常规工艺的加药、加氯量，减轻滤池工作负荷，提高出厂水的卫生安全性。     

日本净化槽技术管理体系经验及启示

对于净化槽,日本已经形成了一套比较完善的技术管理体系,并支撑和规范着净化槽技术的推广和使用.介绍了净化槽技术在日本的发展历史及现状,并从政策法规、技术标准、认证体系、性能评价制度、技术服务体系等方面介绍了净化槽技术管理体系在日本的成功运行经验.完善的技术管理体系是净化槽技术能够在日本推广并健康运行的根本保障.中国在环境保护技术管理体系的建设过程中应积极借鉴国外的成功经验,提高体系建设的科学性、实效性.     

Effect of sludge recirculation on characteristics of hydrogen production in a two-stage hydrogen–methane fermentation process treating food wastes

The two-stage hydrogen–methane fermentation process with different patterns of recirculation was investigated. Operations with the circulation of heat-treated sludge performed considerably better than those with the recirculation of raw sludge with respect to both the hydrogen production rate and yield. In addition, the results of the batch tests demonstrated that circulated sludge was capable of consuming hydrogen under acidogenic pH while the heat-treated sludge was not. These results suggest that the recirculation of active methanogenic sludge had an inhibitive effect on the hydrogen production, which can likely be attributed to the high hydrogen-consuming activity of microorganisms present in the circulated sludge. On the other hand, operations without any sludge recirculation did not perform well in terms of hydrogen production or carbohydrates degradation compared to those with recirculation, perhaps due to a shortage of available nitrogen. This suggests that sludge recirculation in effect supplemented the NH₄⁺ in the hydrogen reactor.     

Iodine-initiated,solid-state copolymerization of tetraoxane with 1,3-dioxolane in the presence of methylal. VI. Studies on copolymer composition

In order to elucidate the mechanism of copolymerization of tetraoxane-1,3-dioxolane, the consumption rate of 1,3-dioxolane was measured by using gas chromatography, and the copolymer composition was determined by high-resolution NMR spectroscopy and differential scanning calorimetry. It was found that 1,3-dioxolane is rapidly consumed in the early stage of copolymerization if 1,3-dioxolane is added at once. The copolymer thus obtained is characterized by a heterogeneous distribution of 1,3-dioxolane in the copolymer chain. However, if 1,3-dioxolane is added continuously during the progress of the copolymerization, the distribution and content of 1,3-dioxolane in the copolymer chain was found to be very homogeneous.     

Iodine-initiated,solid-state copolymerization of tetraoxane with 1,3-dioxolane in the presence of methylal. VIII. Mechanical properties of copolymer

Copolymers obtained by the solid-state copolymerization of tetraoxane with 1,3-dioxolane were pelletized using a vent-type extruder and the mechanical properties were measured. The mechanical properties were found to be largely influenced by the distributions of molecular weight and ethylene oxide, which were controlled by the addition method of the 1,3-dioxolane–methylal solution into polymeric system. The mechanical properties of the copolymers were also found to be intermediate between those of Duracon M90 and Delrin 500.     

A stretchable carbon nanotube strain sensor for human-motion detection

Devices made from stretchable electronic materials could be incorporated into clothing or attached directly to the body. Such materials have typically been prepared by engineering conventional rigid materials such as silicon, rather than by developing new materials. Here, we report a class of wearable and stretchable devices fabricated from thin films of aligned single-walled carbon nanotubes. When stretched, the nanotube films fracture into gaps and islands, and bundles bridging the gaps. This mechanism allows the films to act as strain sensors capable of measuring strains up to 280% (50 times more than conventional metal strain gauges), with high durability, fast response and low creep. We assembled the carbon-nanotube sensors on stockings, bandages and gloves to fabricate devices that can detect different types of human motion, including movement, typing, breathing and speech.