Fluorometric quantification of total d-gluconate by a flow-injection system using an immobilized-enzyme reactor

A method for the quantification of total d-gluconate by flow-injection analysis was developed using an immobilized-enzyme reactor and fluorescence detection. d-Gluconate was quantified using co-immobilized gluconate kinase (GK) and 6-phosphogluconate dehydrogenase (PGDH) reactor. d-Gluconate was phosphorylated to 6-phospho-d-gluconate by GK in the presence of ATP, and then the 6-phospho-d-gluconate produced was oxidized by PGDH with NADP⁺. The NADPH produced by the GK-PGDH reactor was monitored fluorometrically at 455 nm (excitation at 340 nm). A linear relationship between the responses and concentrations of d-gluconate was obtained in the ranges of 1.0 × 10⁻⁶–1.6 × 10⁻⁴ M. The relative standard deviation for 10 successive injections was 0.57% at the 0.1 mM level. This analytical method was applied to the quantification of d-gluconate in honeys, vinegars and noble rot wines, and the results showed good agreement with those obtained using the conventional F-kit method.     

微反应器和微聚合反应器

微反应器是指容量仅为零点几μm^3或宽度为1μm左右的反应“容器”，反应在这个微小区域内有控地进行。以表面科学与微制造技术为核心，新型微反应器近年来发展很快。本文介绍五种微反应器，即反相胶束微反应器，聚合物微反应器，固体模板微反应器，微条纹反应器和微聚合反应器，以及它们在各高科技领域中的可能应用。     

Microdevices for manipulation and accumulation of micro- and nanoparticles by dielectrophoresis

Microfluidic devices with three-dimensional (3-D) arrays of microelectrodes embedded in microchannels have been developed to study dielectrophoretic forces acting on synthetic micro- and nanoparticles. In particular, so-called deflector structures were used to separate particles according to their size and to enable accumulation of a fraction of interest into a small sample volume for further analysis. Particle velocity within the microchannels was measured by video microscopy and the hydrodynamic friction forces exerted on deflected particles were determined according to Stokes law. These results lead to an absolute measure of the dielectrophoretic forces and allowed for a quantitative test of the underlying theory. In summary, the influence of channel height, particle size, buffer composition, electric field, strength and frequency on the dielectrophoretic force and the effectiveness of dielectrophoretic deflection structures were determined. For this purpose, microfluidic devices have been developed comprising pairs of electrodes extending into fluid channels on both top and bottom side of the microfluidic channels. Electrodes were aligned under angles varying from 0 to 75 degrees with respect to the direction of flow. Devices with channel height varying between 5 and 50 microm were manufactured. Fabrication involved a dedicated bonding technology using a mask aligner and UV-curing adhesive. Particles with radius ranging from 250 nm to 12 microm were injected into the channels using aqueous buffer solutions.     

Utility of copper(II) oxide as a packed reactor in flow injection assembly for rapid analysis of some angiotensin converting enzyme inhibitors

A new simple, sensitive, rapid and precise flow injection (FI) procedure based on the formation of copper complexes with some angiotensin converting enzyme (ACE) inhibitors has been developed and evaluated for the analysis of lisinopril (LN), enalapril maleate (EP), ramipril (RP) and perindopril tert-butylamine (PD). In this method, samples were injected into a flowing stream of distilled-deionized water, carried through the packed reactor of CuO for derivatization followed by ultraviolet (UV) detection. The flow rate was 1.5 ml min⁻¹ and column temperature was ambient (25 °C). Lisinopril was injected directly into the flowing stream and the detector response was measured at 262 nm. The hydrolysis products of enalapril maleate, ramipril and perindopril tert-butylamine in 0.2N NaOH were injected after neutralization with 1N HCl and the detector response was measured at 272, 265 and 252 nm, respectively. The developed method was successfully applied to the determination of tested drugs in pharmaceutical preparations at a sampling rate of 60 samples h⁻¹ and a recovery near 100% for all compounds.     

Theoretical treatment of first-order reversible reactions occurring in a chromatographic reactor, on the basis of consecutive reactions

Summary Analytical peak-shape equations were derived for first-order reversible reactions occurring in a chromatographic reactor by treating the reversible reactions as consecutive reactions with alternating products. The results of the analytical peak-shape equations were compared with those from a numerical solution of the partial differential equation system modeling the chromatographic reactor. For small to medium conversions the correspondence was found to be sufficiently close to enable substitution of the numerical solution in fitting procedures for the determination of rate constants. Presented at the 21^st ISC held in Stuttgart, Germany, 15^th–20^th September, 1996     

甲烷直接氧化制甲醇Ⅱ．催化膜反应器（CMR）

采用溶胶－凝胶（Ｓｏｌ－Ｇｅｌ）法制备了微孔结构均匀的“ＳｉＯ＿２／陶瓷”膜和“Ｍｏ－Ｃｏ－·Ｏ／ＳｉＯ＿２／陶瓷”催化功能膜，并用ＸＲＤ、ＳＥＭ和孔径测定等技术进行了表征。在常压、５００～７００℃的条件下，在催化膜反应器（ＣＭＲ）中考察了甲烷氧化制甲醇的反应。在相似的反应条件下（转化率为１．０％），用ＣＭＲ（甲醇选择性１１．２％）可获得较固定床反应器（甲醇选择性４．５％）高得多的甲醇选择性。     

Methane production from synthesis gas using a mixed culture ofR. rubrum M. barkeri,and M. formicicum

The components of synthesis gas, CO, H₂, and CO₂, may be converted into CH₄ biologically through either acetate or H₂/CO₂ as intermediates. Of these two routes, conversion through H₂/CO₂ is preferred. This paper presents results of mixed-culture studies employing the photosynthetic bacteriumR. rubrum for converting CO to CO₂ and H₂ by the water gas shift reaction and two methanogens,M. formicicum andM. barkeri, for converting CO₂ and H₂ into CH₄. Results are presented for triculture operation in two types of reactors, the packed bubble column and the trickle-bed reactor.     

Methane conversion to C2 hydrocarbons in solid electrolyte membrane reactors

Solid electrolyte membrane reactors (SEMRs) have been used to both study and influence catalytic reaction rates. Methane coupling is the reaction most thoroughly and intensively studied in these membrane reactors. In the last 20 years, oxygen ion (O²⁻), proton (H⁺) and mixed (O²⁻-e⁻, H⁺-e⁻) conducting membranes have been tested in order to maximize the conversion of methane to C₂ compounds. The present review contains the fundamental operating principles of the various SEMR types and their applications in this reaction. The difficulties that should be overcome in order to promote this SEMR process to an industrial scale are discussed.     

Flow injection spectrophotometric method for chloride determination in natural waters using Hg(SCN)(2) immobilized in epoxy resin

A flow injection (FI) spectrophotometric method was proposed for the determination of chloride ion in natural waters. The determination of chloride was carried out by reaction with Hg(SCN)₂ immobilized in an epoxy resin bead in a solid-phase reactor (SPR) and the thiocyanate ions released were determined spectrophotometrically at 480 nm after complexing reaction with Fe(III). The analytical curve for chloride was linear in the concentration range from 5.6 × 10⁻⁵ to 2.2 × 10⁻⁴ mol l⁻¹ with a detection limit of 1.4 × 10⁻⁵ mol l⁻¹. The relative standard deviation (R.S.D.) was 2.2% for a solution containing 2.2 × 10⁻⁴ mol l⁻¹ (n = 10). The simple manifold allows a routine analytical frequency of 100 determinations per hour. The main advantage of the developed method is the 400% reduction of the Hg waste solution generated when compared to conventional methods for chloride determination based on the same spectrophotometric reaction.     

催化裂化装置沉降器内结焦的微观结构及其生长过程的分析

对催化裂化装置（FCCU）沉降器内结焦的微观结构进行分析，结果表明，结焦形态主要有4种，丝状焦、滴状焦、块状焦和颗粒状焦。各种结焦形态的成因机理不同，微观结构及生长过程也不同。丝状焦是由铁、镍金属元素催化烃类气体，以及易生焦物发生脱氢缩合反应，以催化剂颗粒形成结焦中心并逐渐长大形成细丝状焦炭；滴状焦是由稠环芳烃脱氢缩合反应而生成，高沸点未汽化油滴黏附在催化剂颗粒或器壁表面形成“焦核”，即由重芳烃、胶质、沥青质脱氢缩合反应和二烯烃聚合环化反应而生成的；块状焦是高沸点未汽化油滴相互溶解后，再脱氢缩合反应或聚合环化反应而形成的结焦；颗粒状焦是油气在气相中脱氢缩合反应或聚合环化反应形成的微小结焦颗粒相互团聚形成的颗粒簇。催化裂化装置沉降器内的结焦一般是上述几种结焦过程的组合，是催化结焦和非催化结焦过程共同作用的结果。