bluuebunny/crossref_metadata_2025_split huggingface dataset:
Divergent consequences arise from metallothionein overexpression in astrocytes: Zinc buffering and oxidant‐induced zinc release
Authors: Malaiyandi Latha M. , Dineley Kirk E. , Reynolds Ian J. 
Published: February 2004

AbstractExcessive accumulation of the heavy metal zinc is cytotoxic. As a consequence, cellular vulnerability to zinc‐induced injury may be regulated by the abundance of proteins that maintain intracellular free zinc concentrations ([Zn2+]i). In this study, we overexpressed the zinc‐binding protein metallothionein‐II (MT) in astrocytes to assess its impact as (1) an acute zinc buffering mechanism, and (2) an oxidant‐releasable zinc pool. Overexpression of MT in primary astrocyte cultures was accomplished using an adenoviral vector. Using the zinc‐sensitive fluorescent indicator mag‐fura‐2, we monitored [Zn2+]i after stimulating zinc influx or oxidant treatment. With MT overexpression, we observed an acute buffering effect manifested as a dampening of stimulus‐induced increases in [Zn2+]i. In contrast, we also saw enhanced zinc release with application of the sulfhydryl oxidizing agent 2,2′‐dithiodipyridine. These results indicate that overexpression of a zinc‐binding protein can quickly diminish [Zn2+]i following zinc influx, but elevate [Zn2+]i under conditions of oxidative stress, providing protective yet potentially endangering effects. © 2003 Wiley‐Liss, Inc.
Electrophysiological and molecular evidence of L‐(Cav1), N‐ (Cav2.2), and R‐ (Cav2.3) type Ca2+ channels in rat cortical astrocytes
Authors: D'Ascenzo Marcello , Vairano Mauro , Andreassi Catia , Navarra Pierluigi , Azzena Gian Battista , Grassi Claudio 
Published: February 2004

AbstractChanges in intracellular Ca2+ levels are an important signal underlying neuron‐glia cross‐talk, but little is known about the possible role of voltage‐gated Ca2+ channels (VGCCs) in controlling glial cell Ca2+ influx. We investigated the pharmacological and biophysical features of VGCCs in cultured rat cortical astrocytes. In whole‐cell patch‐clamp experiments, L‐channel blockade (5 μM nifedipine) reduced Ba2+ current amplitude by 28% of controls, and further decrease (32%) was produced by N‐channel blockade (3 μM ω‐conotoxin‐GVIA). No significant additional changes were observed after P/Q channel blockade (3 μM ω‐conotoxin‐MVIIC). Residual current (36% of controls) amounted to roughly the same percentage (34%) that was abolished by R‐channel blockade (100 nM SNX‐482). Electrophysiological evidence of L‐, N‐, and R‐channels was associated with RT‐PCR detection of mRNA transcripts for VGCC subunits α1C (L‐type), α1B (N‐type), and α1E (R‐type). In cell‐attached recordings, single‐channel properties (L‐currents: amplitude, −1.21 ± 0.02 pA at 10 mV; slope conductance, 22.0 ± 1.1 pS; mean open time, 5.95 ± 0.24 ms; N‐currents: amplitude, −1.09 ± 0.02 pA at 10 mV; slope conductance, 18.0 ± 1.1 pS; mean open time, 1.14 ± 0.02 ms; R‐currents: amplitude, −0.81 ± 0.01 pA at 20 mV; slope conductance, 10.5 ± 0.3 pS; mean open time, 0.88 ± 0.02 ms) resembled those of corresponding VGCCs in neurons. These novel findings indicate that VGCC expression by cortical astrocytes may be more varied than previously thought, suggesting that these channels may indeed play substantial roles in the regulation of astrocyte Ca2+ influx, which influences neuron‐glia cross‐talk and numerous other calcium‐mediated glial‐cell functions. © 2003 Wiley‐Liss, Inc.
Responses and signaling pathways in human optic nerve head astrocytes exposed to hydrostatic pressure in vitro
Authors: Salvador‐Silva Mercedes , Aoi Shun , Parker Amy , Yang Ping , Pecen Paula , Hernandez M. Rosario 
Published: February 2004

AbstractIn this study, we examined the effects of mechanical stress induced by elevated hydrostatic pressure (HP) on the migration of human optic nerve head (ONH) astrocytes, using an in vitro model that follows repopulation of a cell‐free area (CFA) created on a monolayer of cultured astrocytes. α‐Tubulin staining detected phenotypic changes in astrocytes exposed to HP. The influence of proliferation in closure of the CFA was determined by incorporation of BrdU under 1.5‐cm H2O, control pressure (CP), and 10‐cm H2O HP with or without 5‐fluorouracil. Under control and experimental conditions, closure of the CFA occurred mostly by migration and less by proliferation. Exposure to 10‐cm H2O HP induced faster closure of the CFA at 1, 3, and 5 days. The signaling pathways involved in responses to HP were determined using genistein, tyrphostin A25, AG1478, and AG1295, inhibitors of receptor tyrosine kinases; wortmannin and LY294002, inhibitors of phosphatidyl inositol 3‐kinase (PI‐3K); and SC58236, an inhibitor of inducible cyclooxygenase‐2 (COX2). Genistein and tyrphostin A25 blocked HP‐induced migration at 1, 3, and 5 days, but did not affect closure of the CFA under CP. AG1478 and AG1295 blocked HP‐induced migration and partially inhibit closure of the CFA under CP. LY294002 blocked HP‐induced migration. SC58236 markedly inhibited closure of the CFA under CP by inhibiting COX2 activity. Exposure to HP, a physical stress, induced faster closure of the CFA via activation of members of the epidermal growth factor receptor (EGFR) family and PI‐3K pathways. Under CP, closure of the CFA in response to denudation, a form of injury, is due to activation of COX2 in ONH astrocytes. © 2004 Wiley‐Liss, Inc.
Preparation and Analysis of Phenol‐Formaldehyde Resins by High‐Throughput Techniques
Authors: Pasch Harald , Schrod Matthias 
Published: February 2004

AbstractSummary: Phenolic resin composition depends on monomer ratio, catalyst, reaction conditions, and residual free monomers. Using a simple device for parallel synthesis, large numbers of samples of different compositions were prepared. Residual free phenol and formaldehyde were determined by fast HPLC. Using this approach, combinatorial libraries for a huge variety of different experimental conditions can be developed. These libraries bear information on the effect of different experimental parameters on resin composition.magnified image
Combinatorial Methods, Automated Synthesis and High‐Throughput Screening in Polymer Research: The Evolution Continues
Authors: Meier Michael A. R. , Hoogenboom Richard , Schubert Ulrich S. 
Published: February 2004

AbstractSummary: For speeding‐up preparation as well as investigating new polymeric materials, combinatorial techniques, parallel experimentation, and high‐throughput screening methods represent a very promising approach in polymer chemistry: a large variety of parameters can be screened simultaneously resulting in new structure–property relationships. As previously described, polymer chemistry seems to be perfectly suited for combinatorial approaches since it is relatively easy to vary many parameters during the synthesis, processing, blending, or compounding. Moreover, the development and application of high‐throughput screening techniques for polymer properties can accelerate the development of new materials and can result in new structure–property relationships. Therefore, these screening tools, together with parallel preparation techniques, will significantly decrease the time to market of new products. Here we provide an update of our recent overview covering new developments in the field of combinatorial and parallel polymer synthesis and high‐throughput screening.Development of high‐throughput screening techniques for polymer properties.magnified imageDevelopment of high‐throughput screening techniques for polymer properties.
High‐Throughput Chemical Vapor Deposition System and Thin‐Film Silicon Library
Authors: Wang Qi , Liu Fengzhen , Han Daxing 
Published: February 2004

AbstractSummary: Thin‐film Si materials library were fabricated rapidly on glass substrates using the combinatorial hot‐wire CVD technique. We found that the films with high hydrogen dilution become microcrystalline Si, and the films with no and low hydrogen dilution remain in the amorphous Si structure. We also found that the ratio of hydrogen to silane (R) is a good measure of the structure change.Schematics of a combinatorial HWCVD system.magnified imageSchematics of a combinatorial HWCVD system.
High‐Throughput Synthesis of New Ni(II), Pd(II), and Co(II) Catalysts and Polymerization of Norbornene Utilizing the Self‐Made Parallel Polymerization Reactor System
Authors: Cho Hyun Yong , Hong Dae Sik , Jeong Dong Wook , Gong Young‐Dae , Woo Seong Ihl 
Published: February 2004

AbstractSummary: We report the development of new Ni(II), Pd(II), and Co(II) catalysts containing ligands of pyrazolylpyridine derivatives by combinatorial and high‐throughput synthesis technology. Vinyl type polynorbornene was polymerized utilizing the self‐made parallel polymerization reactor system. The Ni(II) catalyst 1 has a polymerization activity of 266.7 kgpolymer · molcat−1 · h−1. We introduce a fast way to conduct catalyst synthesis and high‐throughput screening for polymerization.The self‐made parallel polymerization reactor system.magnified imageThe self‐made parallel polymerization reactor system.
Software Solutions for Combinatorial and High‐Throughput Materials and Polymer Research
Authors: Adams Nico , Schubert Ulrich S. 
Published: February 2004

AbstractSummary: Combinatorial and high‐throughput experimentation has, over the past few years, started to play an increasingly important role in the area of materials and polymer science. However, many of the informatics tools currently available to support combinatorial experimentation were developed with the needs of medicinal and biological chemistry in mind. Recently, companies specialising in cheminformatics software have begun to address the need for dedicated materials informatics tools and, although still in its infancy, the development of such tools is rapidly gathering pace. This short review provides a summary of the current state‐of‐the‐art.
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Applications of High Throughput Research at The Dow Chemical Company
Authors: Peil Kevin P. , Neithamer David R. , Patrick Don W. , Wilson Bruce E. , Tucker Chris J. 
Published: February 2004

AbstractSummary: With high throughput research (HTR), a new research approach towards the development of catalysts and materials has been established at The Dow Chemical Company. While drawing on many of the same concepts as combinatorial chemistry, HTR introduced a new set of specific challenges. New workflows needed to be developed for catalyst and material preparation, activity screens, product and process analytical as well as the management of large amounts of data. Integration of the workflow is critical and requires appropriate skills from such fields as chemistry, engineering, materials, analytical, robotics and informatics. It is not simply having a HTR capability that matters, but what one does with the capability that counts the most. The paradigm shift that has occurred at Dow as a result of HTR will allow Dow to deliver solutions to customers faster than ever. This will be illustrated by several examples of how the HTR capability has had a major impact at Dow.magnified image
Assembly of Nanoparticles using Surface‐Grafted Orthogonal Polymer Gradients
Authors: Bhat Rajendra R. , Tomlinson Michael R. , Genzer Jan 
Published: February 2004

AbstractSummary: We report on preparing poly(2‐(dimethylamino)ethyl methacrylate) (PDMAEMA) gradient substrate, wherein molecular weight (MW) and grafting density (σ) of the surface‐anchored PDMAEMA chains vary continuously in two orthogonal directions. Such a specimen is used to control the assembly of charged gold nanoparticles. Increasing MW and σ of the grafted PDMAEMA cause an enhanced binding of the nanoparticles to PDMAEMA, thus leading to an orthogonal number density gradient of surface‐bound gold nanoparticles.magnified image
A Screening Workflow for Synthesis and Testing of 10,000 Heterogeneous Catalysts per Day – Lessons Learned
Authors: Duff Daniel G. , Ohrenberg Arne , Voelkening Stephan , Boll Matthias 
Published: February 2004

AbstractSummary: For some years now a trend toward the employment of high‐throughput technologies in the development of new catalysts has been apparent in academic and industrial research. One reason is the unmanageably large parameter space present in heterogeneous catalysis, which implies that an increase in throughput in the preparation and testing of candidate substances is necessary, in order to be able to identify a new catalyst in a practicable amount of time. We have tried to locate the current boundaries in achievable throughput. To this end, we developed a workflow in which 10,000 substances per day were synthesised and their activity tested in a heterogeneously catalysed gas phase reaction (alkene epoxidation). The substances were synthesised by dosing precursor solutions onto a single substrate, using ink‐jet printer technology and subsequent thermal treatment. For the activity testing, the product stream of each candidate was conducted through a detection layer, where the target product was converted into a fluorescent substance. By locally resolved fluorescence spectroscopy a rough assessment of each candidate was possible. Because a throughput of 10,000 substances per day is still not able to map the whole parameter space in a practicable amount of time, we used a combination of evolutionary optimisation and data mining as our experiment design strategy for the reduction of the experimental parameter space. It became apparent that a throughput of 10,000 substances per day was only possible at the cost of abstraction and simplification with a concomitant reduction in knowledge gain per individual experiment. Because not every reaction is suited to be simplified in such a manner, whether a high‐throughput screening approach is effective or not has to be considered on a case by case basis.Methods of synthesis and testing to achieve a throughput of 10,000 catalysts per day.magnified imageMethods of synthesis and testing to achieve a throughput of 10,000 catalysts per day.
High‐Throughput Screening of the Influence of Thermal Treatment on the Mechanical Properties of Semicrystalline Polymers: A Case Study for iPP
Authors: Schneider Konrad , Zafeiropoulos Nikolaos Evangelos , Häußler Liane , Stamm Manfred 
Published: February 2004

AbstractSummary: High‐throughput screening is a convenient tool to determine the influence of parameters, such as composition or processing conditions on certain materials' properties. In the present study, iPP was used to construct a combinatorial library made from a processing temperature gradient requiring only a minimised amount of material. Clear changes in the crystalline modification and crystal morphology of the iPP, and their impact on mechanical properties have been identified.The construction of a combinatorial library to study the effect of thermal history upon the properties of polymers.magnified imageThe construction of a combinatorial library to study the effect of thermal history upon the properties of polymers.
A Computational Model for High Speed Screening of Polymer Microstructures
Authors: Wang Kegang , Glicksman Martin E. , Rajan Krishna 
Published: February 2004

AbstractSummary: In this paper we outline a computational strategy that permits the modeling of simultaneous interactions between very large numbers of polymer aggregates. Using a multiparticle diffusion method, we have simulated the dynamics of phase coarsening which can serve as the basis of conducting “virtual” combinatorial experiments and high‐throughput screening of pore size distributions for ultrafiltration membranes.Particle size distributions for various volume fractions of aggregates calculated for two thousand polymer aggregates.magnified imageParticle size distributions for various volume fractions of aggregates calculated for two thousand polymer aggregates.
On the Estimation of Flow Properties of Polyolefins Based on Fast and Conventional Size Exclusion Chromatography
Authors: Gabriel Claus , Lilge Dieter , Laun Hans Martin , Rüllmann Maximilian , Schulze Dirk , Friedrich Christian 
Published: February 2004

AbstractSummary: The present article highlights the possible perdiction of flow properties of polyolefins by fast and conventional size exclusion chromatography measurements. By using a rheological model based on double reptation the viscosity function under shear can be predicted from the molecular mass distribution. The predicted flow curves for polyolefins of narrow molecular mass distributions agree fairly well with the measured data.Comparison of predicted and measured complex viscosity functions of polyethylenes with narrow molecular mass distribution.magnified imageComparison of predicted and measured complex viscosity functions of polyethylenes with narrow molecular mass distribution.
The Combinatorial Approach: A Useful Tool for Studying Epitaxial Processes in Doped Magnetic Semiconductors
Authors: Tsui Frank , Chu Yong S. 
Published: February 2004

AbstractSummary: We describe the recent discovery of promising new Ge‐based magnetic semiconductors and heterostructures using combinatorial molecular‐beam epitaxy for the science and applications of spintronics. We discuss key experimental considerations for implementing combinatorial synthesis and characterization, and highlight important findings in epitaxial films of (100) Ge doped by Co and Mn, specifically the ternary epitaxial phase‐diagram, and the novel magnetic and electrical‐transport phenomena. We illustrate the natural “marriage” between the controlled synthesis and combinatorial approach, and demonstrate the usefulness of the approach for studying complex epitaxial processes.Epitaxial phase‐diagram of CoxMnyGe1 − x − y (100) films.magnified imageEpitaxial phase‐diagram of CoxMnyGe1 − x − y (100) films.
Novel Method for the Synthesis of Molecularly Imprinted Polymer Bead Libraries
Authors: Kempe Henrik , Kempe Maria 
Published: February 2004

AbstractSummary: A novel method for the synthesis of spherical molecularly imprinted polymer (MIP) beads by suspension polymerization in mineral oil is described. The usefulness of the method was demonstrated by the synthesis of a propranolol imprinted MIP library. The composition of the library was generated by statistical experimental design. Multivariate data analysis correlated the screening data, obtained by a radioligand binding assay, to the composition of the MIPs.Light micrograph of MIP beads (MIP 4; size fraction 25–50 μm).magnified imageLight micrograph of MIP beads (MIP 4; size fraction 25–50 μm).
Micro‐Flow Reaction Systems for Combinatorial Syntheses
Authors: Kikutani Yoshikuni , Kitamori Takehiko 
Published: February 2004

AbstractSummary: Micro‐flow chemical processes, which are attracting great attention lately, offer more than the advantage of size. In microspaces, mass and heat transfer lengths are short, the specific interfacial area is large, and heat capacity is remarkably small compared with the situation in conventional scale reaction vessels. These characteristics make precise control of reaction conditions possible, and higher selectivity and conversion can be obtained. In some cases, reactions that are too dangerous to be carried out on a conventional scale can be safely done using micro‐flow reaction systems. Recently, some researchers have developed basic model systems for solution‐phase combinatorial synthesis by utilizing micro‐flow chemical processes. There are two types of combinatorial synthesis systems using micro‐flow chemical processes: parallel reaction systems and sequential reaction systems. In parallel reaction systems, components in starting libraries are simultaneously mixed in all possible combinations by using many micro reaction channels. In addition to needing as many pumps as the starting materials and as many reaction channels as members of the product library, complicated three‐dimensional piping is necessary to connect the pumps and the micro reaction channels. In sequential reaction systems, segments of starting materials are sequentially injected and reacted in a single micro reaction channel in all possible combinations. The latter systems are usually smaller than the former, however, relatively large fluid control devices are necessary in both of them, and improvement of micro‐fluid‐control devices is a critical issue for putting micro‐combinatorial‐synthesis systems to practical use.Parallel micro‐flow reaction system made up of multiple micro chemical chips for combinatorial 2 × 2 synthesis.magnified imageParallel micro‐flow reaction system made up of multiple micro chemical chips for combinatorial 2 × 2 synthesis.
A Cold Plasma Generator and its Applications to Combinatorial Copolymerization of Carbon Dioxide with Organic Molecules
Authors: Terajima Takeshi , Koinuma Hideomi 
Published: February 2004

AbstractSummary: As an energy minimum process for CO2 fixation, we propose the reaction of CO2 with a hydrocarbon excited by our originally designed plasma reactor. In this reactor, the CO2/hydrocarbon ratio and pulsed plasma mode can be changed combinatorially to produce plasma copolymers under sequentially controlled conditions. The presence of CO double bonds in the FT‐IR spectra of the insoluble films confirmed that CO2 has actually been incorporated into the plasma polymerized products.FT‐IR spectra of products copolymerized from a CO2/C2H4 system (a), and relative intensities of the carbonyl absorbance (b).magnified imageFT‐IR spectra of products copolymerized from a CO2/C2H4 system (a), and relative intensities of the carbonyl absorbance (b).
An Electrochemical Robotic System for the Optimization of Amperometric Glucose Biosensors Based on a Library of Cathodic Electrodeposition Paints
Authors: Reiter Sabine , Ruhlig Dirk , Ngounou Bertrand , Neugebauer Sebastian , Janiak Sandra , Vilkanauskyte Aiste , Erichsen Thomas , Schuhmann Wolfgang 
Published: February 2004

AbstractSummary: A library of 148 cathodic electrodeposition paints was synthesized and the properties of related amperometric glucose biosensors were evaluated. For this a novel automatic electrochemical robotic system was designed. The automatic biosensor fabrication and characterization sequence involves the electrochemically induced precipitation of the cathodic paint on the electrode surface in the presence of glucose oxidase, the conditioning of the obtained polymer layer, the recording of a glucose calibration graph and the quantitative dissolution of the polymer film and cleaning of the electrode surface.Schematic representation of the developed electrochemical robotic system for electrochemical screening in microtiter plates.magnified imageSchematic representation of the developed electrochemical robotic system for electrochemical screening in microtiter plates.