Enzyme-Mediated Hydrolysis of Poly(ethylene glycol)-Supported Carbonates

1Introduction Enzymatic kinetic resolution of racemic alcohols or esters is known as a useful method for the preparation of optically active secondary alcohols. However, the work-up including the separation of the mixture of the remaining substrate and the resulting compound spend a lot of time and waste much amount of solvents. On the other hand, organic synthesis based on polymer supports has made rapid progress. Although the methodology is potentially useful for the easy separation of compounds obtained by the enzymatic reaction, there have been relatively few reports on enzymatic resolutions of using a polymer so far. We have noticed that using a watersoluble polymer could be suitable for enzymatic transformation. Here, we report the first example of an enzyme-mediated enantioselective hydrolysis of poly(ethylene glycol)(PEG)-supported substrates with a carbonate moiety to afford optically active compounds, and the method enables us to achieve the easy separation of the products[1]. See Scheme 1.     

Efficient Synthesis of Optically Active Alcohols

1 Introduction Optically active secondary alcohols are versatile building blocks for synthesis of unnatural biological active compounds and functional materials. Therefore, study on efficient synthesis of optically active alcohols is becoming an important subject in synthetic organic chemistry. Catalytic asymmetric reduction of carbonyl compounds is a practical method to create chiral alcohols. For the past decades, a large number of catalytic methods have been developed to achieve this goal. …     

Asymmetric Synthesis Using Enzymes in Supercritical CO2

Great efforts have been extended to catalysis in supercritical CO2（scCO2） since the early 1990＇s due to the environmental friendliness, high diffusivity, high solubilizing power, easiness of the product separation, etc.. A combined process of scCO2 and enzymatic catalyst system would be a promising synthetic tool to produce optically active compounds because the enzyme has advantages of being natural and having high enantioselectivity in nature. Here we report asymmetric synthesis using lipase and alcohol dehydrogenase in scCO2.     

Recent Advances in Protein Extraction and Chiral Separation of Blomolecules

Reverse micelles create unique environment in organic media. They are capable of solubilizing hydrophilic biomolecules （e.g., proteins, peptides, amino acids, and DNAs） in their aqueous interior. This feature brings about the practical use of biomaterials in organic media because reverse micelles solubilize them with the intrinsic activity. In this paper, we focus on recent two topics concerning protein extraction and chiral separation of biomolecules using liquid membranes. In the first topic, we present recent attempts to extract proteins from an aqueous solution into isooctane using reverse micelles, and some important operational parameters to achieve an efficient protein transfer are discussed. Furthermore, novel function of reverse micelles as a protein activation medium is introduced. In the reverse micellar phase, denatured proteins were completely reactivated in the reverse micellar solution. The reverse micellar technique is found to be a useful tool not only for protein separation but also for protein refolding. Furthermore, we found that a cyclic ligand carixarene has an extraction ability to set up optimum conditions for protein transfer. In the second topic, we have found that a supported liquid membrane （SLM） encapsulating enzymes shows high enantioselectivity （enantioselective excess value is over 96%） in the transport of racemic pharmaceutical compound ibuprofen. A different experiment also suggests that the α-chymotrypsin-catalyzed reactions droved the enantioselective transport of L-phenylalanine based on the enantioselectivity of the enzyme. The SLM encapsulating the surfactant-enzyme complex enabled the highly enantioselective separation of racemic mixtures. It can be envisioned that arrangement of appropriate enzymes in the SLM system will allow enantioselective separation of various useful organic compounds.     

New approach for screening anti—tumor compounds

A new screening approach for anticancer active compounds is presented.In this method,a target enzyme is incubated with a mixture of compounds,and then the com-plex formed by the target and small molecules is separated from the rest of the mixture by ultra-filtration.The complex that is retained on the membrane is subsequently washed with acid and small molecules that are specifically bound to the target are released and collected,then analyzed by high-performance liquid chromatograph combined with electrospray ionization mass spectrometry (HPLC/ESI-MS) analysis.We have successfully applied this method to screen anti-cancer compounds.DNA topoisomerase Ⅱ is used as a target to capture anti-tumor candidates from a mixture of combinatorial compounds,such as doxorubicin,daunorubi-cin and pravastain.     

Affinity ultrafiltration of DNA topoisomerases-targeted compounds determined with HPLC／ESI-MS for drug candidate screening

A method of screening assay is demonstrated. The approach is based on the affinity of antitumor candidates for topoisomerases. In this method, antitumor candidates are fished out using topoisomerases as targets. Traditional analysis of complex compounds typically encounters signal suppression due to the relatively low concentrations, but enzyme-affinity screening for the active compounds can effectively concentrate the desired analysts into a small volume of high concen-tration. Active compounds are separated from non-affinity compounds by ultrafiltration. The molecules-enzymes complexes that are retained on the filter are subsequently separated by acidification to obtain the topoisomerases-affinity compounds for analysis on High Performance Liquid Chromatography coupled with electrospray ionization mass spectrometric detec-tion (ESI-MS). This enzyme-affinity based screening assay provides a highly specific and efficient method that can directly screen, identify, and acquire drug candidates thus improving the accuracy and speed of high-throughput screening activities.     

Radical Reactions and Its Synthetic Application

1 Introduction Strategies involving radical reactions have become preeminent tools in organic synthesis. Free radical-mediated cyclization has developed as a powerful method for preparing various types of cyclic compounds via carbon-carbon bond-forming processes. In order to develop effective and convenient methods for the synthesis of biologically active cyclic amines, we have focused our efforts on radical reactions using aldehydes, ketones, and C-C multiple bonds as a radical precursor and…     

Enzymatic Method for Rapid Determination of Oxalic Acid in Bleaching Filtrates from the Pulp and Paper Industry

Bleaching with oxygen-containing agents and recirculation of process streams in the pulp and paper industry has increased the accumulation of oxalic acid and danger for precipitation of calcium oxalate encrusts, scaling. Analysis and control of oxalic acid in bleaching filtrates is therefore becoming increasingly important in the pulp and paper industry. Chromatographic methods, such as IC and HPLC, are generally more time-consuming but are valuable as standard methods for determination of oxalic acid. However, the instrumentation needed is expensive and stationary. In this study, an enzymatic method based on oxalate oxidase and peroxidase was developed to determine oxalic acid in authentic bleaching filtrates using a spectrophotometer. The results showed that bleaching filtrates contain some compounds interfering with the enzymatic method. Pretreatment of the samples with activated charcoal was a successful approach for decreasing problems with interference. By using dilution followed by charcoal treatment, the results obtained from five bleaching filtrates with the colorimetric method correlated very well with those obtained using IC. This study offers a selective, fast and mobile analysis method to determine oxalic acid in bleaching filtrates from the pulp and paper industry. The convenient enzyme-based method improves the possibilities for control of critical oxalic acid concentrations in closed-loop bleaching streams.     

Development of Self-Organized Polymeric Lewis Acid-Catalysts for the Zero-Emission Synthesis of 2-Amino Alcohols

β-Amino alcohols are versatile synthetic intermediates for a wide range of biologically active natural and unnatural products. They can also serve as good chiral ligands for some asymmetric metal complex catalysts. The nucleophilic ring-opening of epoxides with an amine is one of the most efficient routes to obtain such β-amino alcohols with 1,2-trans stereochemistry. Therefore, various homogeneous catalysts have been developed for this transformation. Meanwhile, the development of efficient heterogeneous catalysts that can be easily prepared, recovered, and reused without losing their activities has currently received much attention from a practical and environmental point of view, and not a few such reusable heterogeneous catalysts （e. g. , supported on inorganic materials or insoluble polymers） have been developed. In general, however, they tend to show lower catalytic activities and selectivities compared to the corresponding homogeneous one, and the preparation of them are often tedious.     

An eSnake model for medical image segmentation

A novel scheme of external force for detecting the object boundary of medical image based on Snakes (active contours) is introduced in the paper. In our new method, an electrostatic field on a template plane above the original image plane is designed to form the map of the external force. Compared with the method of Gradient Vector Flow (GVF), our approach has clear physical meanings. It has stronger ability to conform to boundary concavities, is simple to implement, and reliable for shape segmenting. Additionally, our method has larger capture range for the external force and is useful for medical image preprocessing in various applications. Finally, by adding the balloon force to the electrostatic field model, our Snake is able to represent long tube-like shapes or shapes with significant protrusions or bifurcations, and it has the specialty to prevent Snake leaking from large gaps on image edge by using a two-stage segmentation technique introduced in this paper. The test of our models proves that our methods are robust, precise in medical image segmentation.     

Efficiency Improvement of Heterojunction Polymer Photovoltaic Cells through Controlling the Morphology of the Polymer Film

1 Results Polymer photovoltaic cells, which provide clean and renewable energy sources, have gained more and more attention. Polymer photovoltaic cells have the advantage of low fabrication cost and high mechanical flexibility. Polymers can be processed through a solution process, so that a homogeneous polymer film could be readily prepared in a large area. Recently, the light-to-electricity conversion efficiency of the polymer photovoltaic cells was improved significantly[1-2]. Polymer donor and organic acceptor are the two components in the active layer of the polymer photovoltaic cells. The photovoltaic performance is strongly dependent on morphology of the polymer donor/organic acceptor film. The dependences of the film morphology and the device performance on the temperature, solvent and ratio of the polymer donor to acceptor will be reported. Baking of the polymer film at a high temperature significantly affects the absorption and the morphology of the polymer film, which is account for the effect of baking polymer film on the photovoltaic performance. Similar effect on the polymer film morphology and absorption can be achieved by adding small amount of organic molecule into the polymer solution. The photovoltaic performance is related to the structure of the additives.     

A Convenient Method for the Oxidation of Alcohols with KMnO_4 to Their Corresponding Carbonyl Compounds in Ionic Liquid Media

1 Results Carbonyl compounds constitute an important group of molecules in organic chemistry,which appears in pharmaceuticals,dyes and industrially important chemicals[1-2].The oxidation of alcohols to the corresponding carbonyl groups is a fundamental transformation in organic chemistry and industrially important[3].There is considerable interest in the use of room temperature ionic liquids as promising substitutes for volatile organic solvents.The ambient-temperature ionic liquids,especially those based on 1,3-dialkylimidazolium cations,have been emerged as promising green solvents in recent decades[4].Some of the advantages of using ionic liquids in catalytic reactions are connected with the lack of a measurable vapor pressure.Products can be easily distilled out of the reaction mixture and the impact on the environment and operating personnel is dramatically reduced.In addition,due to the great choice of different ionic liquids,the solvent properties may be tuned to suit a particular application.In order to investigate such oxidation reactions in ionic liquids; the selective oxidation of alcohols to aldehydes was selected as a model reaction.     

Large Scale Finite Element Modeling,Simulation and Visualization for Wind Flows in Urban Area Using Virtual Reality

A large-scale finite element modeling, simulation and visualization for wind flows are presented. The modeling method using GIS/CAD data is employed. The stabilized parallel finite element method based on SUPG/PSPG method is employed for the analysis of wind flows. The present method is applied to the simulation of wind flow and contaminant spread in urban area. The visualization based on virtual reality is employed to evaluate the mesh quality and computational results. The computed results are qualitatively in agreement with the experimental results and actual phenomena. The present method is shown to be a useful tool to simulate the wind flows in urban area.     

A novel assistance data processing method for AGPS location system

A method for efficiently transmitting location assistance information to an MS （mobile station） over a control channel with minimal impact on the capacity of the control channel. A location server provides a difference between satellite positions that have been computed using Almanac data and Ephemeris data. Sending only the differ ence between the positions and satellite clock corrections computed using the two different data types. The total amount of information to be transmitted to a MS is significantly reduced. Furthermore, by providing rate of change information, the method allows the location assistance information to remain valid for a relatively long time after it has been received by the MS.     

Numeration and type synthesis of 3-DOF orthogonal translational parallel manipulators

Low-degree-of-freedom （Low-DOF） parallel manipulators （PMs） have drawn extensive interests, particularly in type synthesis in which two main formal approaches were established by using the reciprocal screw system theory and Lie group theory. This paper aims at numeration and type synthesis of orthogonal translational parallel manipulators （OTPMs） by resorting to an integration of the group- based method and graphical representation of the topology. For this purpose, the concept of Cartesian DOF-characteristic matrix, orig- inated from displacement subgroup and displacement submanifold, is proposed. A new approach based on the combination of the atlas of Cartesian DOF-characteristic matrix and the displacement group-theoretic method is addressed for both exhaustive classification and type synthesis of OTPMs. The proposed approach is prone to construct an orthogonal structure and is easy to realize the complete classification and exhaustive enumeration of this class of low-DOF PMs.     

Polymer Photovoltaic Cells

Polymer photovoltaic cells （PPVCs） have attracted much attention recently because of its easy fabrication, low cost and possibility to make flexible devices. PPVC is composed of a conjugated polymer/C60 blend layer （photosensitive layer） sandwiched between a transparent ITO electrode and a metal electrode. When a light through ITO electrode irradiates on the photosensitive layer, the photons with appropriate energy will be absorbed by the conjugated polymer （CP） and excitons （electron-hole pair） are produced. The excitons move to the interface of CP/60 where the electrons transfer to the LUMO of C60 and holes leave on the HOMO of the CP. The separated electrons migrate through the C60 network to and are collected by the metal electrode, and the holes migrate through the CP network to and are collected by the ITO electrode, so that the photocurrent and photovoltage are attained.     

Investigation on wavelength switching of widely tunable SGDBR lasers

The sampled-grating distributed Bragg reflector （SGDBR） laser is a typical and important photonic integrated device, and has potential wide application to agile optical networks. A new dynamic model for this device has been developed, which combines the traveling-wave method for the active region and the transfer-matrix method for the passive sections into a single procedure. The behaviors of wavelength switching of the SGDBR laser, which include the transient spectrum and mode competition, have been studied in detail using this model. A new efficient way has been proposed to improve the wavelength switching performance only by increasing the coupling coefficients without changing the carrier density.     

CMAC Based Color Separation in Printing Images

To over come the drawbacks existing in current measurement methods for detecting and controlling colors in printing process, a new medal for color separation and dot recognition is proposed from a view of digital image processing and patter recognition. In this model, firstly data samples are collected from some color patches by the Fuzzy C-Means （FCM） method; then a classifier based on the Cerebellar Model Articulation Controller （CMAC） is constructed which is used to recognize color pattern of each pixel in a microscopic halftone image. The principle of color separation and the algorithm model are introduced and the experiments show the effectiveness of the CMAC-based classifier as opposed to the BP network.     

A Steady-State Errors Correction Method for Eliminating Measurement Errors

This paper proposes a steady-state errors correction （SSEC） method for eliminating measurement errors.This method is based on the detections of error signal E（s） and output C（s） which generate an expected output R （s）.In comparison with the conventional solutions which are based on detecting the expected output R （s） and output C （s） to obtain error signal E （s）,the measurement errors are eliminated even the error might be at a significant level.Moreover,it is possible that the individual debugging by regulating the coefficient K for every member of the multiple objectives achieves the optimization of the open loop gain.Therefore,this simple method can be applied to the weak coupling and multiple objectives system,which is usually controlled by complex controller.The principle of eliminating measurement errors is derived analytically,and the advantages comparing with the conventional solutions are depicted.Based on the SSEC method analysis,an application of this method for an active power filter （APF） is investigated and the effectiveness and viability of the scheme are demonstrated through the simulation and experimental verifications.     

Towards larger spatiotemporal scales in polymer simulations

Molecular dynamics simulations are useful tools to unveil molecular mechanisms of polymer phase separation,self-assembly,adsorption,and so on.Due to large molecular size and slow relaxation of the polymer chains,a great amount of issues related to large-distance chain displacement cannot be tackled easily with conventional molecular dynamic simulations.Systematic coarse-graining and enhanced sampling methods are two types of improvements that can boost spatiotemporal scales in polymer simulations.We present two typical ways to obtain the coarse-graining potential either by fitting to correct liquid structures or by fitting to available thermodynamic properties of polymer systems.The newly proposed anisotropic coarse-grained particle model can be used to describe aggregation and assembly of polymeric building blocks from disk-like micelles to Janus particles.We also present a stochastic polymerization model combined with coarse-grained simulations to investigate the problems strongly influenced by the coupling of polymerization and excluded volume effects.Finally,a facile implementation of integrated tempering sampling method is illustrated to be very efficient on bypassing local energy minima and having access to true equilibrium polymer structures.