One step method of structure engineering porous graphitic carbon nitride for efficient visible-light photocatalytic reduction of Cr(Ⅵ)

Porous g-C3N4 nanosheets (PCN) were prepared by the nickel-assisted one-step thermal polymerization method.Hydrogen (H2) which was produced by the reaction between nickel (Ni) foam and ammonia (NH3) defined the structure and properties of PCN.During the formation of PCN,the participation of H2 not only enhanced the spacing between layers but also boosted the specific surface area that more active sites were exposed.Additionally,H2 promoted pores formation in the nanosheets,which was beneficial to the transfer of photons through lamellar structure and improved the absorption efficiency of visible light.Remarkably,the obtained PCN possessed better Cr(Ⅵ) photocatalytic reduction efficiency than pure g-C3N4.The reaction rate constant (k) of PCN (0.013 min-1) was approximately twice that of bare g-C3N4 (0.007 min-1).Furthermore,the effects of original pH and concentration of Cr(Ⅵ)-containing solution on removal efficiency of Cr(Ⅵ) were explored.A possible photocatalytic mechanism was proposed based on the experiments of radical scavengers and photoelectrochemical characterizations.     

Screening of frozen-thawed conditions for keeping nutritive compositions and physicochemical characteristics of goat milk

Frozen milk can help producers overcome the seasonality of goat milk production, low goat production and short lactation periods, and avoid discarding milk during some special periods. We investigated effects of combination between freezing (cryogenic refrigerator of ?16 to ?20°C or ultra-cryogenic refrigerator of ?76 to ?80°C) and thawing (homeothermy of 20 to 25°C or refrigeration of 2 to 4°C) on nutritive compositions and physicochemical characteristics of raw goat milk during storage period (80 d). Compared with fresh goat milk, the frozen-thawed milk decreased contents of fat, protein, and lactose, as well as surface tension and stability coefficient, whereas increased effective diameter and polydispersity index. The average values of color values (L*, a*, and b*) in 4 group samples changed from 83.01 to 82.25, ?1.40 to ?1.54, 3.51 to 3.81, respectively, and the ΔE of most samples did not exceed 2. In contrast to the other 3 frozen-thawed treatments, goat milk treated with ultra-cryogenic freezing-homeothermic thawing (UFHT) possessed higher fat (5.20 g/100 g), smaller effective particle diameter (0.32 µm), and the lowest polydispersity index value (0.26). The color and confocal laser scanning microscopy images of UFHT were similar to those of fresh goat milk, illustrating UFHT was the optimal approach to maintain the natural quality of goat milk. Our finding provides a theoretical basis for producers to freeze surplus milk.     

家庭网络的业务和技术详述

首先分析了家庭网络的具体业务和应用．然后详细介绍了家庭网络涉及的各项关键技术。     

广东省智能网工程建设

本文介绍了广东省智能网的组网方案及所能提供的业务,并论述了智能网工程建设,安装维护以及与广东省现有移动通信网联网中存在的一些问题。     

用于光城域网的新型RPR技术

介绍IEEE802.17正在进行标准化的弹性分组环(RPR,Resilient Packet Ring)协议,分析其帧结构及主要功能特色,并和SDH与以太网等现有城域网技术作简要对比;可以预见,随着标准化工作的进行,综合多种传输技术优势的RPR会成为创建下一代高速光城域网的首选技术。     

帧中继交换技术

本文论述了帧中继交换的概念、标准，结构、特点网络式样及在互连网中的应用。     

泥沙起动条件及机理的非线性研究

 分析了单颗粒、均匀沙及非均匀沙的起动现象及其机理，认为泥沙的起动属于突变论研究的范畴。从泥沙起动所遵循起动条件的力学规律出发，导出泥沙起动条件方程。在此基础上，利用尖点突变性质对各种泥沙起动现象及机理进行了描述和说明。     

本征吸除硅片特性研究

本文描述硅本征吸杂片的特性参数,如吸除区宽度、洁净度,氧沉淀密度、MOS电容寿命,介绍了表面态密度及残余间隙氧浓度的检测方法和工艺对参数的影响及参数之间的内在联系,文章还实验论证了不同参数水平对器件成品率的影响,建立了以MOS电容寿命为主导的参数控制方法,利用本文提供的控制参数,可使CCD-512器件成品率达60％,以上优品率≥85％。     

RS码频域纠错编码在激光对潜通信信道中的实现方法

介绍了信道编码在激光对潜通信系统中的重要作用，介绍了频域编译ＲＳ码的基本方法，并给出了脉冲位置调制信道的ＲＳ码频域编译码的计算机模拟方法和结果。