变压吸附制氧法与深冷法的比较

全面比较变压吸附制氧法与深冷法的工艺过程、运行参数、技术指标、水电消耗、基建投资、经营成本、技术安全、占地面积、建设要求、操作维护和操作人数等,指出各自的优缺点和适用范围,供用户选择时参考。

浅述医用氧与分子筛制氧法

随着医疗卫生事业的不断发展,新型医疗设备的不断出现,新的制氧设备制得的氧气含量问题越来越受人们关注。本文较为详细地从国家规定、制氧方法及现实状况等方面,概述了医用氧及分子筛制氧装置的现状及面临的问题,为医用氧及制氧装置的发展提供了参考意见。

实验室内简易装置制氧法介绍

在实验室利用过氧化氢溶液的不稳定性,其遇氧化物KMnO4或者MnO2等就会迅速分解的原理,利用简易装置即可制备氧气,并将氧气收集于皮囊中,以备使用.在临床情境下,也可直接用胶管输给需氧患者.

磁分制氧机理

本文讨论了横向非均匀磁场对氧气和氨气的分离作用，论证了在常温常压下直接从空气中提取富氧的机理。

以空气为原料的电化学提取氧研究

研究了一种以空气为原料的电化学氧提取方法 .该氧提取分离系统以泡花镍为阳极 ,碳 -聚四氟乙烯空气电极为阴极 ,KOH溶液为电解液 .利用常规的滴定分析方法测定了电解液中各种离子的浓度 ,并利用气相色谱测定了电解气中的氧气纯度 (体积分数 ) .实验结果表明 ,生产每公斤氧气的耗电量为 1.5 6～ 1.86kW·h ,电解气中的氧气含量 (体积分数 )可达 99.8%以上 ,反应主要以阴极消耗空气中的氧气生成OH- 和HO- 2 ,阳极OH- 和HO- 2

化学氧源

综述了化学氧源中氯酸盐及过氧化物产氧剂的组成、制备及应用。

Optimizing Poly(heptazine imide)Photoanodes Using Binary Molten Salt Synthesis for Water Oxidation Reaction

Polymer-based photoanodes for the water oxidation reaction have recently garnered attention,with carbon nitride standing out due to its numerous advantages.This study focuses on synthesizing crystalline carbon nitride photoanodes,specifically poly(heptazine imide)(PHI),and explores the role of salts in their production.Using a binary molten salt system,optimal photocurrent density of 365μA·cm^(−2)was achieved with a voltage bias of 1.23 V versus the reversible hydrogen electrode under AM 1.5G illumination,this performance is ca.18 times to the pristine PCN photoanode.In this process,NH_(4)SCN facilitates the growth of SnS_(2)seeding layers,while K_(2)CO_(3)enhances film crystallinity.In situ electrochemical analyses show that this salt combination improves photoexcited charge transfer efficiency and minimizes resistance in the SnS_(2)layer.This study clarifies the role of salts in synthesizing the PHI photoanode and provides insights for designing high-crystallinity carbon nitride-based functional films.

钦州市耕地资源的生态价值核算

耕地是人类社会得以生存和发展的基本资源,其物质价值包括经济价值、社会价值和生态价值3个方面。在立足于钦州市耕地资源利用现状的基础上,运用固碳制氧法核算钦州市耕地资源的生态价值。研究表明,钦州市耕地资源的生态价值为798 637.33元/hm2,显示出耕地资源具有巨大的经济价值。长期以来,耕地的生态价值一直被忽略,有关部门应该高度重视这部分价值,对其进行科学量化,让耕地生态价值观念更深入人心,真正实现耕地资源的可持续利用。

Effect of Enzymes in Buccal Mucous Membrane on Buccal Absorption of Insulin

To evaluate the effect of proteolytic enzymes on the absorption of insulin in the buccal mucosa, the trichloroacetic acid (TCA) method was used to estimate the degradation of insulin under different conditions in the buccal mucosal homogenates. In vivo experiments estimating the enhancement of hypoglycaemic effect by enzyme inhibitors were also conducted. The results showed that proteolytic enzymes in the buccal mucosa were less active than in the intestine. Bacitracin, aprotinin and sodium deoxycholate could inhibit the degradation of insulin in the buccal mucosal homogenates. The degradation of insulin in buccal mucosal homogenates of normal hamsters was smaller than that of diabetic hamsters. In vivo experiments of hypoglycaemia supported the in vitro results. When given buccally, bacitracin, aprotinin and sodium deoxycholate could increase the relative pharmacological bioavailability of insulin. When co-administered with aprotinin(0.1%), bacitracin(0.5%) and sodium deoxycholate(5%), the relative pharmacological bioavailabilities of insulin were 4.84%, 6.60% and 14.95% respectively. The in vitro and in vivo results suggest that proteolytic enzymes are present in the buccal mucosa, which limit absorption of insulin. Co-administration with some enzyme inhibitors can improve the bioavailability of insulin via buccal delivery and sodium deoxycholte is more efficient than some enzyme inhibitors used for improving buccal absorption.

Research Advances in the Inhibition of Long Chain Fatty Acid to Methanogenic Activity in Anaeroic Digestion System

This article reviewed the inhibition mechanism of long chain fatty acid on the formation of anaerobic system, then thoroughly analyzed the inhibition factors of long chain fatty acid, and summarized the remission method to its inhibition, finally proposed some suggestions to further study on the influence of long chain fatty acid on anaerobic digestion system.

Preparation and application of perovskite-type oxides for electrocatalysis in oxygen/air electrodes

Recent advances in the preparation and application of perovskite-type oxides as bifunctional electrocatalysts for oxygen reaction and oxygen evolution reaction in rechargeable metal-air batteries are presented in this review.Various fabrication methods of these oxides are introduced in detail,and their advantages and disadvantages are analyzed.Different preparation methods adopted have great influence on the morphologies and physicochemical properties of perovskite-type oxides.As a bifunctional electrocatalyst,perovskite-type oxides are widely used in rechargeable metal-air batteries.The relationship between the preparation methods and the performances of oxygen/air electrodes are summarized.This work is concentrated on the structural stability,the phase compositions,and catalytic performance of perovskite-type oxides in oxygen/air electrodes.The main problems existing in the practical application of perovskite-type oxides as bifunctional electrocatalysts are pointed out and possible research directions in the future are recommended.

Influence of preparation methods on the physicochemical properties and catalytic performance of MnO_x-CeO_2 catalysts for NH_3-SCR at low temperature

This work examines the influence of preparation methods on the physicochemical properties and catalytic performance of MnOx‐CeO2 catalysts for selective catalytic reduction of NO by NH3 (NH3‐SCR) at low temperature. Five different methods, namely, mechanical mixing, impregnation,hydrothermal treatment, co‐precipitation, and a sol‐gel technique, were used to synthesizeMnOx‐CeO2 catalysts. The catalysts were characterized in detail, and an NH3‐SCR model reaction waschosen to evaluate the catalytic performance. The results showed that the preparation methodsaffected the catalytic performance in the order: hydrothermal treatment > sol‐gel > co‐precipitation> impregnation > mechanical mixing. This order correlated with the surface Ce3+ and Mn4+ content,oxygen vacancies and surface adsorbed oxygen species concentration, and the amount of acidic sitesand acidic strength. This trend is related to redox interactions between MnOx and CeO2. The catalystformed by a hydrothermal treatment exhibited excellent physicochemical properties, optimal catalyticperformance, and good H2O resistance in NH3‐SCR reaction. This was attributed to incorporationof Mnn+ into the CeO2 lattice to form a uniform ceria‐based solid solution (containing Mn‐O‐Cestructures). Strengthening of the electronic interactions between MnOx and CeO2, driven by thehigh‐temperature and high‐pressure conditions during the hydrothermal treatment also improved the catalyst characteristics. Thus, the hydrothermal treatment method is an efficient and environment‐friendly route to synthesizing low‐temperature denitrification (deNOx) catalysts.

Preparation and Characterization of a Perovskite-type Mixed Conducting SrFe0.6Cu0.3Ti0.1O3-δ Membrane for Partial Oxidation of Methane to Syngas

Dense membrane with the composition of SrFe0.6Cu0.3Ti0.1O3-δ （SFCTO） was prepared by solid state reaction method. Oxygen permeation flux through this membrane was investigated at operating temperature ranging from 750℃ to 950℃ and different oxygen partial pressure. XRD measurements indicated that the compound was able to form single-phased perovskite structure in which part of Fe was replaced by Cu and Ti. The oxygen desorption and the reducibility of SFCTO powder were characterized by thermogravimetric analysis and temperature programmed reduction analysis, respectively. It was found that SFCTO had good structure stability under low oxygen pressure at high temperature. The addition of Ti increased the reduction temperature of Cu and Fe. Performance tests showed that the oxygen permeation flux through a 1.5 mm thick SFCTO membrane was 0.35-0.96 ml·min ^-1·cm^-2 under air/helium oxygen partial pressure gradient with activation energy of 53.2 kJ·mol^-1. The methane conversion of 85%, CO selectivity of 90% and comparatively higher oxygen permeation flux of 5 ml·min^-1·cm^- 2 were achieved at 850℃, when a SFCTO membrane reactor loaded with Ni-Ce/Al2O3 catalyst was applied for the partial oxidation of methane to syngas.

Urea Preparation by Oxidative Carbonylation of Ammonia

Effective one-stage method of urea preparation by catalytic oxidative carbonylation of ammonia in liquid phase is developed. The method allows to prepare urea with productivity of-530 g/（L·h） in sufficiently mild conditions （total pressure -30 bar, 45 ℃）. The process is characterized by high selectivity （near 100%） i.e. byproducts separation is not needed. Almost all CO is consumed during the process, this substantially diminishes the waste-gas purification costs and raises the process environmental characteristics; the only byproduct is water.

Fabrication and Characterization of Alumina/CNTs Nanocomposite Powders, by CCVD Method and Investigation of the Parameter Involved

Ceramics in general and particularly alumina （Al2O3） are important materials in various industries, but the main problem with these materials is related to some of their mechanical properties including low resistance against mechanical shock （hardness-toughness）, which makes them to be so brittle, and possession of high degree of porosity which reduces their strength and gives them fragile characteristics. Researchers report indicates that the presence of the second phase with suitable properties can improve some of the mechanical properties of these materials and optimize their characteristic. Carbon nanotubes with unique physical characteristics such as large aspect ratio, high strength and Young＇s modulus and improved thermal properties could be suitable candidates for this purpose. In this study, the growth of multi wall carbon nanotubes （MWCNTs） on the alumina support as the matrix of the composite has been carried out, using catalytic chemical vapor deposition （CCVD） method in which the iron nanoparticles has been selected as catalyst materials. Ethylene gas is used as feed materials for carbon source and argon as the carrier gas. In order to achieve a more comprehensive results, we have investigated the effects of some fabricating parameters like catalyst particle size, its weight percentage related to support material, alumina and to the some synthesizing temperature gases flow rate. Fabricated ceramics composites samples structures were analyzed using SEM images as well as Raman scattering spectra and X-ray diffraction pattern.

Preparation of AgSnO_2 composite powders by hydrothermal process

Silver-tin oxide powders were synthesized by the hydrothermal method with Ag(NH_3)_2^+ solution and Na_2SnO_3 solution as raw materials and Na_2SO_3 as reductant. The precipitation conditions of Na2SnO3 solution and the reduction conditions of Ag(NH_3)_2^+ were also investigated. The powders prepared were characterized by differential thermal analysis (DTA), X-ray diffraction analysis (XRD), scanning electron microscope (SEM) and energy spectrum analysis. The results show that pH value of the solution is a key parameter in the formation of Sn(OH)_4 precipitate and the reduction reaction of Ag(NH_3)_2^+ can release H+ ions, which results in synchronous precipitation of Sn(OH)_6~2- as Sn(OH)_4. The reduction of Ag(NH_3)_2^+ and precipitation of Na_2SnO_3 occur simultaneously and the coprecipitation of silver and tin oxide is reached by the hydrothermal method. The silver-tin oxide composite powders have mainly flake shape of about 0.3 μm in thickness and there exists homogeneous distribution of tin oxide and silver in the powder synthesized.

Optimized One-Step Preparation of a Bioactive Natural Product,Guaiazulene-2,9-dione

We previously isolated a natural product, namely guaiazulene-2,9-dione showing strong antibacterial activity against Vibrio anguillarum, from a gorgonian Muriceides collaris collected in South China Sea. In this experiment, guaiazulene-2,9-dione was quantitatively synthesized with an optimized one-step bromine oxidation method using guaiazulene as the raw material. The key reaction condition including reaction time and temperature, drop rate of bromine, concentration of aqueous THF solution, respective molar ratio of guaiazulene to bromine and acetic acid, and concentration of guaiazulene in aqueous THF solution, were investigated individually at five levels each for optimization. Combined with the verification test to show the absolute yield of each optimization step, the final optimal condition was determined as: when a solution of 0.025 mmol m L-1 guaiazulene in 80% aqueous THF was treated with four volumes of bromine at a drop rate of 0.1 m L min-1 and four volumes of acetic acid at-5℃ for three hours, the yield of guaiazulene-2,9-dione was 23.72%. This was the first report concerning optimized one-step synthesis to provide a convenient method for the large preparation of guaiazulene-2,9-dione.

Preparation and Characterization of Alumina Membranes on Capillary Supports： Effect of Film-coating on Crack-free Membrane Preparation

Ceramic capillary membrane has received much attention due to its relatively high pack density and favorable mechanical strength.However,it is difficult to prepare capillary membrane on its thin support by a dip-coating method.In this study,alumina microfiltration membranes were prepared on the inner surface of alumina capillary support(outer diameter 4 mm,inner diameter 2.5 mm)by a dip-coating method.Scanning electron microscopy(SEM)observation,gas bubble pressure(GBP)method and membrane permeation test were carried out to evaluate membrane performance.Two major effects in preparation of crack-free membrane,capillary filtration and film-coating,upon the thin support were studied.The as-prepared crack-free membrane presents a narrow pore size distribution,a mean pore size of about 0.6μm and a high pure water flux of 86000 L·m -2 ·h -1 ·MPa.It is proved that the membrane thickness should be sufficiently large to overcome the defects of support surface,but it is only one of the prerequisites for the formation of crack-free membrane.Furthermore,it is demonstrated that the capillary filtration effect is greatly restricted for thin capillary support with the dip-coating method and the film-coating effect plays a crucial role in the formation of crack-free membrane.

Preparation of Surfactant-Free Pt and PtRu Nanoparticles with High Activity for Methanol Oxidation

A simple and green approach to synthesize highly active electro-catalysts for methanol oxi- dation reaction （MOR） without using any organic agents is described. Pt nanoparticles are directly deposited on the pre-cleaned and pre-oxidized multiwall carbon nanotubes （MWC- NTs） from Pt salt by using CO as the reductant. MOR activity has been characterized by both cyclic voltammetry and chronoamperometry, the current density and mass specific current at the peak potential （ca. 0.9 V vs. RHE） reaches 11.6 mA/cm^2 and 860 mA/mgpt, respectively. After electro-deposition of Ru onto the Pt/MWCNTs surface, the catalysts show steady state mass specific current of 20 and 80 mA/mgpt at 0.5 and 0.6 V, respectively.

Importance, features and uses of metal oxide catalysts in heterogeneous catalysis

This short review paper aims at assembling the present state of the art of the multiuses of metal oxides in heterogeneous catalysis, concerning liquid and gaseous phases of the reactant mixtures on solid catalysts. It includes the description of the main types of metal oxide catalysts, of their various preparation procedures and of the main reactions catalysed by them (acid-base type, selective and total oxidations, bi-functional catalysis, photocatalysis, biomass treatments, environmental catalysis and some of the numerous industrial applications). Challenges and prospectives are also discussed.