催醒宁定量分析——亚硝酸反应法的研究

催醒宁,又名优色林,化学名称为1、3、3—三甲基-5-二甲氨基甲酰氧基吲哚满盐酸盐,化学结构式为:催醒宁是一种可逆性胆碱酯酶抑制剂,临床上可用作中麻催醒、治疗青光眼及缩瞳等用药。为解决制剂中催醒宁的含量测定,必须建立一个简便而又专一的定量分析方法。

尿沉渣分析仪对尿液中细菌测定性能及对尿路感染的筛查价值

目的评估UF-1000i型全自动尿沉渣分析仪对细菌检测性能和筛查尿路感染的价值。方法尿沉渣分析仪以流式细胞技术作为测定原理,对非离心尿液中的红细胞、白细胞、上皮细胞、管型和细菌等进行定量测定;针对细菌的测定就尿定性检查中的亚硝酸盐反应及培养检查尿路感染之间的相关性;使用UF-1000i细菌散点图模型对区别杆菌和球菌的可能性进行研究。结果 UF-1000i尿沉渣分析仪对细菌测定的灵敏度为95.2%,特异度为70.2%,测得细菌尿液中亚硝酸盐阳性率为15.2%,细菌培养后以大肠杆菌最为多见,通过细菌散点图模型培养出细菌杆菌的一致率为94.7%,球菌的一致率为82.5%。结论通过细菌散点图分布的不同可以大致判定细菌是杆菌还是球菌。

Nitrogen Removal by Simultaneous Nitrification and Denitrification via Nitrite in a Sequence Hybrid Biological Reactor

Sequence hybrid biological reactor （SHBR） was proposed, and some key control parameters were investigated for nitrogen removal from wastewater by simultaneous nitrification and denitrification （SND） via nitrite. SND via nitrite was achieved in SHBR by controlling demand oxygen （DO） concentration. There was a programmed decrease of the DO from 2.50 mg·L^-1 to 0.30 mg·L^-1, and the average nitrite accumulation rate （NAR） was increased from 16.5% to 95.5% in 3 weeks. Subsequently, further increase in DO concentration to 1.50 mg·L^-1 did not destroy the partial nitrification to nitrite. The results showed that limited air flow rate to cause oxygen deficiency in the reactor would eventually induce only nitrification to nitrite and not further to nitrate. Nitrogen removal efficiency was increased with the increase in NAR, that is, NAR was increased from 60% to 90%, and total nitrogen removal efficiency was increased from 68% to 85%. The SHBR could tolerate high organic loading rate （OLR）, COD and ammonia-nitrogen removal efficiency were greater than 92% and 93.5%, respectively,, and it even operated under low DO concentration （0.5 mg·L^-1） and maintained high OLR （4.0 kg COD·m^-3·d^-1）. The presence of biofilm positively affected the activated sludge settling capability, and sludge volume index （SVI） of activated sludge in SHBR never hit more than 90 ml·L^-1 throughout the experiments.

Nitrosation Reaction Without Nitrogen Oxide Waste Gas Emission and Its Engineering Practice

The gas-liquid phase equilibrium is used in controlling the nitrosation reaction process. Decomposition of nitrous acid and oxidation side reaction.are suppressed in a closed reaction system. The system pressure is used as the criterion of the end of reaction, avoiding excessive feeding and reducing＇the decomposition＇of nitrous acid. The head space of the reactor is used as the gas buffer, stabilizing the feeding fluctuations and inhibiting the side reaction, decomposition of nitrous acid. Nitrogen oxide concentration is controlled at the minimum level.Thus the zero release ofnitrogen ox!de waste gas can be achieved without using any absorption process.

UF-1000i尿有形成分分析仪、尿干化学分析与尿细菌培养的比较

目的运用全自动尿液有形成分分析仪UF-1000i检测出的白细胞计数(WBC)、细菌定量计数(BACT)、细菌散点图和干化学法检测的亚硝酸盐反应(NIT)与尿液细菌培养结果的比对分析。方法用255人份样本做尿液干化学分析和有形成分分析,同时进行细菌培养及鉴定,对结果进行相关性分析。结果白细胞与细菌培养比对显示其具有较高的灵敏度为83%,但是其特异性为5.8%及误诊率为94.2%;细菌定量计数是拥有较高的灵敏度为97.2%和符合率为72.9%,但特异性为42%,应重视其参考价值,但不能作为诊断依据;细菌散点图应用能快速进行致病菌类别的判定,对合理使用药物有较好的参考价值;亚硝酸盐反应对尿路细菌感染的灵敏度为27.2%,其特异性很高为100%,一旦反应为阳性,基本判定有细菌感染的存在。结论尿液干化学分析项目的检测仍是目前诊断尿路感染的重要指标,尿液有形分析仪检测的细菌散点图是一种良好的判定致病菌的指标,但它们都存在一定的误诊率和漏诊率,而尿液细菌培养因报告时间较长,不能及时有效的为临床诊疗服务。了解其特点,联合应用能弥补单项指标的不足,从而提高泌尿道感染的诊断、治疗及疗效监测。

Reaction mechanism of methyl nitrite dissociation during co catalytic coupling to dimethyl oxalate:A density functional theory study

Dissociation of methyl nitrite is the first step during CO catalytic coupling to dimethyl oxalate followed by hydrogenation to ethyl glycol in a typical coal to liquid process. In this work, the first-principle calculations based on density functional theory were performed to explore the reaction mechanism for the non-catalytic dissociation of methyl nitrite in the gas phase and the catalytic dissociation of methyl nitrite on Pd(111) surface since palladium supported on alpha-alumina is the most effective catalyst for the coupling. For the non-catalytic case, the calculated results show that the CH_3O–NO bond will break with a bond energy of 1.91 eV, and the produced CH_3O radicals easily decompose to formaldehyde, while the further dissociation of formaldehyde in the gas phase is difficult due to the strong C–H bond. On the other hand, the catalytic dissociation of methyl nitrite on Pd(111) to the adsorbed CH_3O and NO takes place with a small energy barrier of 0.03 eV. The calculated activation energies along the proposed reaction pathways indicate that(i) at low coverage, a successive dehydrogenation of the adsorbed CH_3O to CO and H is favored while(ii) at high coverage, hydrogenation of CH_3O to methanol and carbonylation of CH_3O to methyl formate are more preferred. On the basis of the proposed reaction mechanism,two meaningful ways are proposed to suppress the dissociation of methyl nitrate during the CO catalytic coupling to dimethyl oxalate.

Effect of substrate concentration on stability of anammox biofilm reactors

Ammonium and nitrite are two substrates of anammox bacteria, but they are also inhibitors under high concentrations. The performance of two anaerobic ammonium-oxidizing (anammox) upflow biofilm (UBF) reactors was investigated. The results show that anammox UBFs become unstable under nitrogen loading rate (NLR) applied higher than 1.0 g/(L·d). The consumptions of acidity in the anammox reaction lead to the increase of pH, which is as high as 8.70-9.05. Free nitrous acid concentration is accompanied to be lower than the affinity constant of anammox bacteria, and then starvation effect appears. Moreover, free ammonia concentration increases to 57-178 mg/L, resulting in inhibitory effect on the anammox bacteria. Both negative effects contribute to the instability of the anammox bioreactors.

Carbon dioxide induced degradation of diethanolamine during absorption and desorption processes

Alkanolamines are widely used in the purification of the sourgas sweetening process. During the sour gas absorption process, CO_2 significantly degrades the amine solvent and creates enormous problems for plant operation. In this work, CO_2 induced degradation of aqueous diethanolamine(DEA) solution was conducted in a 1.25 L jacketed glass reactor that functioned as an absorber and stripper at atmospheric conditions. Pure CO_2 was bubbled through the reactor until the solution became saturated. In this study, the concentrations of DEA used were in the range of concentrations between 2 mol·L^(-1) and 4 mol·L^(-1). In the degradation experiment, six generic cycles were conducted for each run. Each cycle was configured with the absorption and desorption of carbon dioxide at 55 ℃ and 100 ℃, respectively. Samples were collected after a predetermined experimental time and analyzed by ion chromatography(IC) to identify unknown ionic degradation products(DGPs). In the IC analysis, three different columns were used for anion, cation and ion exclusion systems, which are Metrosep A Supp 5150/4.0, Metrosep C Supp 4 150/4.0 and Metrosep Organic Acids, respectively. The major identified DGPs of D01 DEA2 M, D02 DEA3 M, and D03 DEA4 M are nitrite, acetate and ammonium. Phosphate product was found in the degraded amine samples which might be due to the contamination of water or chromatographic system.

亚硝酸盐型甲烷厌氧氧化及其功能微生物研究进展

亚硝酸盐型甲烷厌氧氧化(Nitrite-Dependent Anaerobic Methane Oxidation,N-DAMO)是耦合氮循环和碳循环的关键环节,主要是由亚硝酸盐型甲烷厌氧氧化菌(Candidatus Methylomirabilis oxyfera)介导完成,对于研究全球氮和碳元素的生物地球化学循环具有重要意义。本文首先总结了国内外N-DAMO的影响因素和在不同自然生态系统中的分布,然后阐述了N-DAMO菌的生理生化特性及其富集培养优化实验和检测技术,最后探讨了N-DAMO技术的应用现状。本综述不仅有助于揭示全球碳氮循环的耦合作用机制,也为N-DAMO反应耦合其他厌氧生物处理过程应用到污水的除碳脱氮上提供了理论依据。

Completely Autotrophic Nitrogen-removal over Nitrite in Two Types of Reactors

Two lab-scale reactors, suspended-sludge and fluidized.bed, were conducted with the feed of ammonium-rich synthetic wastewater devoid of COD. Completely autotrophic nitrogen-removal process was fulfilled in both reactors and the maximum efficiencies of nitrogen removal were achieved, 65% in the suspended-sludge reactor and 73% in the fluidized-bed reactor respectively. Different from the steady performance of the fluldized-bed reactor, the suspended-sludge reactor came to deteriorate constantly after a period of stable operation, resulting in almost complete loss of the N-removal ability in the suspending system. Molecular methods such as PCR and FISH were employed for describing the microbial characteristics in two systems. This study suggests that a biofllm system is a suitable configuration for completely autotrophic N-removal with more feasibility and stability than a suspending system.

Advanced nitrogen removal via nitrite from municipal landfill leachate using a two-stage UASB–A/O system

A system consisting of a two-stage up-flow anaerobic sludge blanket （UASB） reactor and an anoxic/aerobic （A/O） reactor was used to treat municipal landfill leachate. Denitrification took place in the first stage of the UASB reactor （UASB1）. The chemical oxygen demand of the UASB1 effluent was further decreased in the second stage （UASB2）. Nitrification was accomplished in the A/O reactor. When diluted with tap water at a ratio of 1：1, the ammonia nitrogen concentration of the influent leachate was approximately 1200 mg· L^-1, whereas that of the system effluent was approximately 8-11 mg· L^-1, and the corresponding removal efficiency is about 99.08%. Stable partial nitrification was achieved in the A/O reactor with 88.61%-91.58% of the nitrite accumulation ratio, even at comparatively low temperature （ 16℃）. The results demonstrate that free ammonia （FA） concentrations within a suitable range exhibit a positive effect on partial nitrification. In this experiment when FA was within the 1-30 mgmg· L^-1 range, partial nitrification could be achieved, whereas when FA exceeded 280 mgmg· L^-1, the nitrification process was entirely inhibited. Temperature was not the key factor leading to partial nitrification within the 16-29 ℃ range. The inhibitory influence of free nitrous acid （FNA） on nitrification was also minimal when pH was greater than 8.5. Thus, FA concentration was a major factor in achieving partial nitrification.

Comparisons of measured nitrous acid(HONO) concentrations in a pollution period at urban and suburban Beijing, in autumn of 2014

To study the HONO formation mechanisms during a pollution period, a continuous measurement was performed in both urban and suburban aeras of Beijing. During this period, the PM2.5 concentrations increased to 201 and 137 ?g/m3 in urban and suburban areas, respectively. The concentrations of HONO, CO, SO2, O3, NO, NO2, NOx were 1.45 ppbv, 0.61 ppmv, 8.7 ppbv, 4.3 ppbv, 44.4 ppbv, 37.4 ppbv, 79.4 ppbv and 0.72 ppbv, 1.00 ppmv, 1.2 ppbv, 7.9 ppbv, 3.7 ppbv, 8.2 ppbv, 11.9 ppbv, in urban and suburban areas, respectively. To compare possible pathways of HONO formation in both sites, the contributions of direct emissions, heterogeneous formations, and homogeneous productions were studied. HONO/NO2 ratios in the two sites indicated that heterogeneous reactions of NO2 were more efficient in suburban areas. And in both urban and suburban areas, the increase of PM2.5 concentrations and RH would promote the conversion efficiency in RH that ranged from 0% to 85%. However, when RH was above 85%, the HONO formation slowed down. Moreover, the study of direct emissions and homogeneous reactions showed that they contributed to a majority of HONO increase in urban areas than the 20% contributions in suburban areas. It implied that the high NOx concentrations and NO concentrations in urban areas or in pollution periods would make direct emissions and homogeneous reactions become dominant in HONO formations.