A Closed Concept of Extractive Whole Cell Microbial Transformation of Benzaldehyde into l-Phenylacetylcarbinol by Saccharomyces cerevisiae in Novel Polyethylene-Glycol-Induced Cloud-Point System

Extractive microbial transformation of benzaldehyde into l-phenylacetylcarbinol (l-PAC) by Saccharomyces cerevisiae (Baker’s yeast) has been carried out in a novel polyethylene-glycol-induced cloud-point system (PEG-CPS). The extractive microbial transformation in the PEG-CPS and a downstream process for stripping of the product from the microbial transformation broth with microemulsion extraction are demonstrated. The results indicate that the PEG-CPS maintains the advantage of CPS for in situ extraction of polar product in the microbial transformation. At the same time, the utilization of hydrophilic nonionic surfactant in the PEG-CPS is favorable for stripping of product from the nonionic surfactant in the microbial transformation broth by Winsor I microemulsion extraction. Thus, a closed concept of in situ extraction of polar product in microbial transformation and its downstream process of product recovery are fulfilled at the same time.     

Isotachophoresis for rapid transformation of Escherichia coli

A frequent limitation of electroporation (EP) and chemical transformation (CT) are the need of tedious and time-consuming procedures for inducing transformation competence, the substantial number of cells required, and the low transformation yields typically achieved. Here, we show a new and rapid electrokinetic method for transformation of small number of noncompetent Escherichia coli TOP10 cells (2–3 × 10⁵) at room temperature. Escherichia coli TOP10 cells and plasmid DNA are sequentially injected into a 50 μm ID capillary and focused into 11.5 nL by isotachophoresis (ITP) induced by application of high DC voltage (–16 kV). Through ITP, a large excess of plasmid DNA is brought in contact with the cell surface, with the contact time adjusted by application of a counter-pressure (1.3 psi) opposing the ITP movement. The transformation rate was more than 1000-fold higher compared to EP and CT at survival rates greater than 60%.     

Comparison of various optimization approaches for fed-batch ethanol production

Various optimization techniques have been proposed to optimize the feedrate profile to maximize ethanol production. Among them are the differential algebraic system (DAS) approach, Kelly transformation approach, singular control approach, and on-off control approach. These methods are compared and it is shown that the DAS approach and Kelly transformation method are equivalent. A nonsingular transformation approach is presented. The performance obtained with the nonsingular approach is the same as that obtained with the singular approach and better than those obtained with the DAS and on-off control approaches.     

Insight into Biomass Upgrade: A Review on Hydrogenation of 5-Hydroxymethylfurfural (HMF) to 2,5-Dimethylfuran (DMF)

Recent developments in the transformation of biobased 5-hydroxymethylfurfural (HMF) into a potential liquid fuel, 2,5-dimethylfuran (DMF), are summarised. This review focuses briefly on the history of HMF conversion to DMF in terms of the feedstock used and emphasises the ideal requirements in terms of the catalytic properties needed in HMF transformation into DMF. The recent state of the art and works on HMF transformation into DMF are discussed in comparison to noble metals and non-noble metals as well as bimetallic catalysts. The effect of the support used and the reaction conditions are also discussed. The recommendations for future work and challenges faced are specified.     

Application of Enzymatic Method in the Extraction and Transformation of Natural Botanical Active Ingredients

Active components from traditional Chinese medicine (TCM) are the material basis for disease treatment. Extraction, identification, and transformation are the critical processes to analyze and use the active components of TCM. Botanic TCM takes up 90 % of total Chinese crude drugs. Some active components are complex and of lower level; moreover, most of them are enveloped under plant cell wall. Traditional extraction methods such as lixiviate method, decoction, and others are often hindered by cell wall, leading to low extraction efficiency, low clearance of impurity, and other problems, which have restricted the development of TCM. This paper reviews both domestically and internationally published literatures in recent years on application of enzymatic methods in the extraction and transformation of active ingredients from TCM. Principles of enzymatic method and its application in extraction and transformation of active ingredients and in dreg recycles of TCM are introduced in detail. With the development of TCM modernization, enzymatic method applied in the domain of TCM has achieved prominent benefits, not only improving the extraction and separation rate of active ingredients from TCM and elevating the transformation level and production, but also reducing costs in the transformation of active ingredients.     

Some general characteristic properties of substituted cyclopentadienes

A number of substituted cyclopentadienes display characteristic properties which are representate of all members in the series: (a) the endocyclic double bond isomers are in the thermodynamic equilibrium; the process of establishing the equilibrium being retarded; (b) the transformation of isomeric cyclopentadienes proceeds by steps, i.e. a proton from the methylene group (5th position) passes mainly to the adjacent C-atom (1st position). The proton-cyclopentadienyl anions are probably transitional states in the transformation of isomers. It is assumed that this transformation is a first order reaction. As a result of this investigation it has been shown that the structure of the substituted cyclopentadiene (or the composition of the isomer mixtures) depends mainly on the character of the substituent and not on the method of synthesis.²     

Fe(II)-induced transformation from ferrihydrite to lepidocrocite and goethite

The transformation of Fe(II)-adsorbed ferrihydrite was studied. Data tracking the formation of products as a function of pH, temperature and time is presented. The results indicate that trace of Fe(II) adsorbed on ferrihydrite can accelerate its transformation obviously. The products are lepidocrocite and/or goethite and/or hematite, which is different from those without Fe(II). That is, Fe(II) not only accelerates the transformation of ferrihydrite but also leads to the formation of lepidocrocite by a new path. The behavior of Fe(II) is shown in two aspects—catalytic dissolution-reprecipitation and catalytic solid-state transformation. The results indicate that a high temperature and a high pH(in the range from 5 to 9) are favorable to solid-state transformation and the formation of hematite, while a low temperature and a low pH are favorable to dissolution-reprecipitation mechanism and the formation of lepidocrocite. Special attentions were given to the formation mechanism of lepidocrocite and goethite.     

Kinetics of the 20°C phase transformation in polytetrafluoroethylene

The rate at which PTFE transforms from the triclinic to the hexagonal phase has been measured under isothermal conditions. Samples in a series of decreasing density and crystallinity show increased isothermal rates of transformation. Observed kinetic data are interpreted on the basis of a modified Avrami-Johnson-Mehl treatment. A model for the transformation in which planes of helix-hand reversal propagate through the lattice is shown to fit the experimental results. The transformation rate is observed to be proportional to the total (001) surface area in the polytetrafluoroethylene specimens, suggesting that nucleation of the transformation takes place at grain boundaries.     

Enantioselective conjugate addition of alkenylboronic acids to indole-appended enones

An enantioselective addition of alkenylboronic acids and alkynylboronic esters to unprotected indole-appended enones is reported. This transformation proceeds with high enantioselectivity and high product yields via the use of catalytic amounts of 3,3'-bis(pentafluorophenyl)-BINOL and Mg(Ot-Bu)(2). A range of α-branched indole derivatives are available from the transformation.     

Scenarios of heterogeneous nucleation and growth studied by cell dynamics simulation

The dynamics of phase transformation due to homogeneous nucleation has long been analyzed using the classic Kolmogorov-Johnson-Mehl-Avrami (KJMA) theory. However, the dynamics of phase transformation due to heterogeneous nucleation has not been studied systematically even though it is vitally important technologically. In this report, the author studies the dynamics of heterogeneous nucleation theoretically and systematically using the phenomenological time-dependent Ginzburg-Landau (TDGL)-type model combined with the cell dynamics method. In this study the author focuses on the dynamics of phase transformation when the material is sandwiched by two supporting substrates. This model is supposed to simulate phase change storage media. Since both homogeneous and heterogeneous nucleations can occur simultaneously, the author predicts a few scenarios of phase transformation including homogeneous nucleation regime, heterogeneous nucleation regime, and the homogeneous-heterogeneous coexistence regime. These predictions are directly confirmed by numerical simulation using the TDGL model. The outcome of the study was that the KJMA formula has limited use when heterogeneous nucleation exists, but it could still give some information about the microscopic mechanism of phase transformation at various stages during phase transformation.     

迭代目标转换因子分析与人工神经网络法用于邻、间、对硝基甲苯的分光光度同时测定的比较研究

本文将迭代目标转换因子分析与人工神经网络法用于分光光度法同时测定邻、间、对硝基甲苯,并与目标转换因子分析的结果进行了比较.结果表明,迭代目标转换因子分析法与线性网络法的效果都很好.其相对误差分别为1.3％和1.2％,而目标转换因子分析法的预测误差较大,其相对误差为10.4％.     

Influence of additives and water vapour on the transformation of transition aluminas into alpha alumina

Addition of magnesium cations to gamma (and delta) alumina enhances its rate of transformation into alpha alumina, whereas addition of zirconium cations inhibits it. The effect of adding both magnesium and zirconium cations at various concentrations from 0.5 to 5% to aluminium ions has been studied. The kinetic curves of transformation into alpha alumina at 1373 K are reported. The effects observed are in agreement with the D.T.A. measurements. Changes in surface area accompanying the phase transformation have also been measured. A synergy effect may occur between magnesium and zirconium behaviours, since maximum stabilization of the surface area is found with a particular co-doped product (Mg²⁺(1%)-Zr⁴⁺(0.5%)).In the case of pure alumina, the influence of water vapour in the range 1–20 torr has also been investigated with the same methods. The results show that water vapour enhances the rate of transformation into alpha.     

Transformations of benzene-argon mixture in barrier discharge

The transformation of a benzene-argon mixture in dielectric-barrier discharge (DBD) was studied. Benzene-soluble polymeric compounds (76.5 wt %), biphenyl (7.6 wt %), and phenylcyclohexadienes (9 wt %) are the major products. Monoalkylbenzenes, cyclohexadienes, and ethynylbenzene are in trace amounts in the reaction mixture. The benzene conversion per pass through the discharge zone was 5.5 wt %. The possible mechanism of the benzene transformation in DBD was suggested on the basis of experimental data and theoretical calculations.     

Length‐Scale‐Dependent Phase Transformation of LiFePO4: An In situ and Operando Study Using Micro‐Raman Spectroscopy and XRD

The charge and discharge of lithium ion batteries are often accompanied by electrochemically driven phase‐transformation processes. In this work, two in situ and operando methods, that is, micro‐Raman spectroscopy and X‐ray diffraction (XRD), have been combined to study the phase‐transformation process in LiFePO₄ at two distinct length scales, namely, particle‐level scale (～1 μm) and macroscopic scale (～several cm). In situ Raman studies revealed a discrete mode of phase transformation at the particle level. Besides, the preferred electrochemical transport network, particularly the carbon content, was found to govern the sequence of phase transformation among particles. In contrast, at the macroscopic level, studies conducted at four different discharge rates showed a continuous but delayed phase transformation. These findings uncovered the intricate phase transformation in LiFePO₄ and potentially offer valuable insights into optimizing the length‐scale‐dependent properties of battery materials.     

Synthesis of novel block copolymers through electron transfer system by smi2

This paper summarizes our recent efforts to offer block copolymers through the transformation reactions of a cationic growing center into an anionic one by the utilization of divalent samarium complexes. Four types of transformation reactions are described, and their scope and limitations are discussed. Several applications of these transformation reactions are also presented.     

Application of complementary mass spectrometric techniques to the identification of ketoprofen phototransformation products

Ketoprofen (KP) is a nonsteroidal anti-inflammatory drug, which during UV irradiation rapidly transforms into benzophenone derivatives. Such transformation products may occur after topical application of KP, which is then exposed to sunlight resulting in a photo-allergic reaction. These reactions are mediated by the benzophenone moiety independently of the amount of allergen. The same reactions will also occur during wastewater or drinking water treatment albeit their effect in the aqueous environment is yet to be ascertained. In addition, only a few such transformation products have been recognised. To enable the detection and structural elucidation of the widest range of KP transformation products, this study applies complementary chromatographic and mass spectrometric techniques including gas chromatography coupled to single quadrupole or ion trap mass spectrometry and liquid chromatography hyphenated with quadrupole-time-of-flight mass spectrometry. Based on structural information gained in tandem and multiple MS experiments, and on highly accurate molecular mass measurements, chemical structures of 22 transformation products are proposed and used to construct an overall breakdown pathway. Among the identified transformation products all but two compounds retained the benzophenone moiety--a result, which raises important issues concerning the possible toxic synergistic effects of KP and its transformation products. These findings trigger further research into water treatment technologies that would limit their entrance into environmental or drinking waters.     

Phase transformation of colloidal In2O3 nanocrystals driven by the interface nucleation mechanism: a kinetic study

The kinetics of phase transformation of colloidal In(2)O(3) nanocrystals (NCs) during their synthesis in solution was explored by a combination of structural and spectroscopic methods, including X-ray diffraction, transmission electron microscopy, and extended X-ray absorption fine structure spectroscopy. Johnson-Mehl-Avrami-Erofeyev-Kholmogorov (JMAEK) and the interface nucleation models were used to analyze the isothermal kinetic data for the phase transformation of NCs in the temperature range of 210-260 °C. The results show that NCs are initially stabilized in the metastable corundum (rh-In(2)O(3)) phase. The phase transformation occurs via nucleation of cubic bixbyite (bcc-In(2)O(3)) phase at the interface between contacting rh-In(2)O(3) NCs, and propagates rapidly throughout the NC volume. The activation energy of the phase transformation was determined from the Arrhenius expression to be 152 ± 60 kJ/mol. The interface nucleation rate is maximal at the beginning of the phase transformation process, and decreases over the course of the reaction due to a decrease in the concentration of rh-In(2)O(3) NCs in the reaction mixture. In situ high-temperature XRD patterns collected during nonisothermal treatment of In(2)O(3) NCs reveal that phase transformation of smaller NCs occurs at a faster rate and lower temperature, which is associated with their higher packing density and contact formation probability. Because NC surfaces and interfaces play a key role in phase transformation, their control through the synthesis conditions and reaction kinetics is an effective route to manipulate NC structure and properties.     

Alkyne-to-vinylidene transformation on trans-(Cl)Rh(phosphine)2: acceleration by a heterocyclic ligand and absence of bimolecular mechanism

Alkyne-to-vinylidene transformation on square-planar trans-(Cl)Rh(phosphine)2 has been proposed to proceed by a mechanism with a key step being bimolecular transfer of hydridic H to an alkynyl carbon. Labeling studies reported here are inconsistent with this pathway. In addition, an imidazolyl substituent accelerates the transformation.     

土壤有机氯脱氯转化的界面交互反应*

有机氯杀虫剂、除草剂等难降解有机物是重要的土壤污染物。近年来,有机氯脱氯转化的界面过程已成为土壤环境科学的研究热点。本文综述了土壤有机氯脱氯转化的界面非生物过程、界面生物过程以及界面生物－非生物交互反应过程。界面脱氯转化过程与主要土壤化学过程、土壤根际过程相互关联,该过程中,铁物种循环与铁氧化物的异化还原溶解扮演了重要角色。     

Candida tenuis xylose reductase catalysed reduction of acetophenones: the effect of ring-substituents on catalytic efficiency

The catalytic efficiencies of Candida tenuis xylose reductase catalysed reductions of mono-substituted acetophenones are in reasonable correlation with the σ-Hammett coefficients of the substituted phenyl groups. Variations of the substrate transformation rates are hence mainly caused by mesomeric and inductive effects of the substituents, while differences in substrate binding have a secondary relevance. Some substrate (1)H NMR chemical shifts and carbonyl IR absorption bands are in reasonable accordance with the catalytic activities and allow the estimation of the transformation rates with good accuracy. The resulting substituted (S)-1-phenyl ethanols are generated in very high enantiomeric excess.