bluuebunny/crossref_metadata_2025_split huggingface dataset:
Eutectic Gallium‐Indium (EGaIn): A Liquid Metal Alloy for the Formation of Stable Structures in Microchannels at Room Temperature
Authors: Dickey Michael D. , Chiechi Ryan C. , Larsen Ryan J. , Weiss Emily A. , Weitz David A. , Whitesides George M. 
Published: March 2008

AbstractThis paper describes the rheological behavior of the liquid metal eutectic gallium‐indium (EGaIn) as it is injected into microfluidic channels to form stable microstructures of liquid metal. EGaIn is well‐ ;suited for this application because of its rheological properties at room temperature: it behaves like an elastic material until it experiences a critical surface stress, at which point it yields and flows readily. These properties allow EGaIn to fill microchannels rapidly when sufficient pressure is applied to the inlet of the channels, yet maintain structural stability within the channels once ambient pressure is restored. Experiments conducted in microfluidic channels, and in a parallel‐plate rheometer, suggest that EGaIn's behavior is dictated by the properties of its surface (predominantly gallium oxide, as determined by Auger measurement s); these two experiments both yield approximately the same number for the critical surface stress required to induce EGaIn to flow (∼0 .5 N/m). This analysis–which shows that the pressure that must be exceeded for EGaIn to flow through a microchannel is inversely proportional to the critical (i.e., smallest) dimension of the channel–is useful to guide future fabrication of microfluidic channels to mold EGaIn into functional microstructures.
A Protection Strategy Substantially Enhances Rate and Enantioselectivity in ω‐Transaminase‐Catalyzed Kinetic Resolutions
Authors: Höhne Matthias , Robins Karen , Bornscheuer Uwe T. 
Published: March 2008

AbstractThe kinetic resolution of 3‐aminopyrrolidine (3AP) and 3‐aminopiperidine (3APi) with ω‐transaminases was facilitated by the application of a protecting group concept. 1‐N‐Cbz‐protected 3‐aminopyrrolidine could be resolved with >99% ee at 50% conversion, the resolution of 1‐N‐Boc‐3‐aminopiperidine yielded 96% ee at 55% conversion. The reaction rate was up to 50‐fold higher by using protected substrates. Most importantly, enantioselectivity increased remarkably after carbamate protection compared to the unprotected substrates (86 vs. 99% ee). Surprisingly, benzyl protection of 3AP had no influence on enantioselectivity. A possible explanation for this observation could be the different flexibility of the benzyl‐ or carbamate‐protected 3AP as confirmed by NMR spectroscopy.
Organic Semiconductors for Solution‐Processable Field‐Effect Transistors (OFETs)
Authors: Allard Sybille , Forster Michael , Souharce Benjamin , Thiem Heiko , Scherf Ullrich 
Published: March 2008

AbstractThe cost‐effective production of flexible electronic components will profit considerably from the development of solution‐processable, organic semiconductor materials. Particular attention is focused on soluble semiconductors for organic field‐effect transistors (OFETs). The hitherto differentiation between “small molecules” and polymeric materials no longer plays a role, rather more the ability to process materials from solution to homogeneous semiconducting films with optimal electronic properties (high charge‐carrier mobility, low threshold voltage, high on/off ratio) is pivotal. Key classes of materials for this purpose are soluble oligoacenes, soluble oligo‐ and polythiophenes and their respective copolymers, and oligo‐ and polytriarylamines. In this context, micro‐ or nanocrystalline materials have the general advantage of somewhat higher charge‐carrier mobilities, which, however, could be offset in the case of amorphous, glassy materials by simpler and more reproducible processing.
Preparation and characterization of metal‐complex imprinted PVDF hollow fiber membranes
Authors: Wang Xue‐Jun , Xu Zhen‐Liang , Bing Nai‐Ci , Yang Zuo‐Guo 
Published: March 2008

AbstractUsing nickel‐2,2′‐dipyridyl complex as a template, N‐vinyl‐2‐pyrrolidone as the metal coordination functional monomer, and ethylene glycol dimethacrylate as the crosslinker, polyvinylidene fluoride (PVDF) hollow fiber ultrafiltration membrane as the supported membrane, metal complex imprinted polymeric membranes were prepared. The association constant of template‐monomer interaction in the prepolymerization solution was estimated to be 4.38 × 104 (L/mol)2 by spectrophotometric titration analysis. The attenuated total reflection Fourier transform infrared spectroscopy and scanning electron micrograph characterization indicated that the surface of the support PVDF membrane was completely coated by the imprinted polymer layer after modification. The imprinted membranes exhibited the selective permeability for the template in certain nickel acetate solution. The molecularly imprinted membranes gave higher permeation separation factors at about pH 6, whereas increasing pressure would lower the separation ability. The effects of ion concentration, cations and counterions, ligand selectivity, pH, and trans‐membrane pressure were investigated and the permeation performances of the imprinted membranes could be regarded as facilitated transport mechanism. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Adhesion properties of pressure‐sensitive adhesives prepared from SMR 10/ENR 25, SMR 10/ENR 50, and ENR 25/ENR 50 blends
Authors: Poh B. T. , Lim A. L. 
Published: March 2008

AbstractThe adhesion properties, i.e. viscosity, tack, and peel strength of pressure‐sensitive adhesives prepared from natural rubber/epoxidized natural rubber blends were investigated using coumarone‐indene resin and toluene as the tackifier and solvent respectively. One grade of natural rubber (SMR 10) and two grades of epoxidized natural rubbers (ENR 25 and ENR 50) were used to prepare the rubber blends with blend ratio ranging from 0 to 100%. Coumarone‐indene resin content was fixed at 40 parts per hundred parts of rubber (phr) in the adhesive formulation. The viscosity of adhesive was measured by a HAAKE Rotary Viscometer whereas loop tack and peel strength was determined using a Lloyd Adhesion Tester operating at 30 cm/min. Results show that the viscosity of the adhesive passes through a minimum value at 20% blend ratio. For loop tack and peel strength, it indicates a maximum at 60% blend ratio for SMR 10/ENR 25 and SMR 10/ENR 50 systems. However, for ENR 25/ENR 50 blend, maximum value is observed at 80% blend ratio. SMR 10/ENR 25 blend consistently exhibits the best adhesion property in this study, an observation which is attributed to the optimum compatibility between rubbers and wettability of adhesive on the substrate. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Improving the colorfastness of poly(ethylene terephthalate) fabrics with the natural dye of Caesalpinia sappan L. Wood extract and the effect of chitosan and low‐temperature plasma
Authors: Park Youngmi , Koo Kang , Kim Samsoo , Choe Jongdeok 
Published: March 2008

AbstractThe effect of a low‐temperature plasma and/or chitosan pretreatment as a mordant on the dyeing of poly(ethylene terephthalate) fabrics with an aqueous extract of Caesalpinia sappan L. wood, which showed a remarkably high coloring property in a natural dyeing system, was investigated. After dyeing, scanning electron microscopy, add‐on, color measurements, and fastness to washing tests were performed. Dyeing with the C. sappan L. extract led to fair‐to‐good fastness properties in conventional natural dyeing. The results clearly show that the pretreatment with chitosan and/or plasma is better than a metal mordant in terms of the dye uptake and reduction in the dyeing time, that the proposed pretreatment coloration reaction could be carried out without the need for repetitive dye steps, and that it prevents the excessive use of dye chemicals, thereby resulting in a more ecofriendly process. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Effect of a carbon black surface treatment on the microwave properties of poly(ethylene terephthalate)/carbon black composites
Authors: Koysuren Ozcan , Yesil Sertan , Bayram Goknur , Secmen Mustafa , Civi Ozlem Aydin 
Published: March 2008

AbstractA surface treatment was applied to carbon black to improve the electrical and microwave properties of poly(ethylene terephthalate) (PET)‐based composites. Three different formamide solutions with 1, 2, and 3 wt % concentrations were prepared to modify the surface chemistry of carbon black. Microwave properties such as the absorption loss, return loss, insertion loss, and dielectric constant were measured in the frequency range of 8–12 GHz (X‐band range). Composites containing formamide‐treated carbon black exhibited enhancements in the electrical conductivity, electromagnetic interference (EMI) shielding effectiveness, and dielectric constant values when compared to composites with untreated carbon black. In addition, increases in the formamide solution concentration and carbon black content of composites resulted in an increase in the electrical conductivity, EMI shielding effectiveness, and dielectric constant values. The percolation threshold concentration of PET composites shifted from a 3 to 1.5 wt % carbon black composition with the surface treatment. The best EMI shielding effectiveness was around 27 dB, which was obtained with the composite containing 8 wt % carbon black treated with a 3 wt % formamide solution. Moreover, this composition gave the lowest electrical resistivity and the highest dielectric constant among the produced composites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Selective decomposition of the siloxane bond constituting the crosslinking element of silane‐crosslinked polyethylene by supercritical alcohol
Authors: Goto Toshiharu , Yamazaki Takanori , Sugeta Tsutomu , Okajima Izumi , Sako Takeshi 
Published: March 2008

AbstractMaterial recycling of silane‐crosslinked polyethylene (silane‐XLPE) was investigated to make thermoplastic polyethylene (PE). To make thermoplastic PE from silane‐XLPE, a crosslinking element that consists of a siloxane bond must selectively be decomposed. Supercritical alcohol and water were adopted in this study. An autoclave was applied to expose silane‐XLPE to the supercritical fluid. The structure of the products was analyzed with 29Si‐NMR, Fourier transform infrared, gel fraction, and molecular weight measurements. The results showed that the siloxane bond was successfully decomposed selectively by supercritical alcohol. It was expected that the structure of the recycled PE would be close to that of the silane‐grafted PE. To confirm this expectation, the recycled PE was cured in saturated water vapor to investigate the crosslinking ability. The recycled PE, silane‐grafted PE, and silane‐grafted PE with a catalyst for condensation were compared. The kinetics and activation energy were calculated from the data of the temperature dependence of the increment of the gel fraction. The results showed that the recycled PE still had the ability to undergo a crosslinking reaction. The kinetics and activation energy of the recycled PE were closer to those of silane‐grafted PE than to those of silane‐grafted PE with a catalyst. The activity of the catalyst must have been lost by supercritical alcohol. These data support the expectation of the structure of the recycled PE. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Improving the resistance to humid heat sterilization of EVOH copolymers through blending
Authors: Lopez‐Rubio Amparo , Lagaron Jose M. 
Published: March 2008

AbstractThe effect of retorting, i.e., combined temperature and high relative humidity conditions, on the morphology, structure, and thermal characteristics of a number of extruded films containing binary and ternary blends of a 32 mol % ethylene‐vinyl alcohol copolymer (EVOH) with amorphous polyamide (aPA) and nylon‐containing ionomer as blending additives was carried out. Each film was investigated by differential scanning calorimetry, attenuated total reflectance Fourier transformed infrared spectroscopy (ATR‐FTIR), scanning electron microscopy (SEM), and synchrotron X‐ray scattering. The oxygen transmission rate of multilayer structures having as barrier element the cited blends was also measured and the results were interpreted in terms of the blends' particular structural and morphological features. From the results it was found that the thermal properties, the crystalline structure, and the water resistance of the blends were improved upon retorting compared with neat EVOH. However, only the binary blend with aPA showed a real enhancement in the oxygen barrier properties immediately after retorting compared with neat EVOH. This unprecedented and surprising effect was additionally ascribed to the retorting‐induced compatibilization between EVOH and aPA components of the blend as determined by SEM. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
High‐throughput screening of chromatographic separations: IV. Ion‐exchange
Authors: Kelley Brian D. , Switzer Mary , Bastek Patrick , Kramarczyk Jack F. , Molnar Kathleen , Yu Tianning , Coffman Jon 
Published: March 2008

AbstractIon‐exchange (IEX) chromatography steps are widely applied in protein purification processes because of their high capacity, selectivity, robust operation, and well‐understood principles. Optimization of IEX steps typically involves resin screening and selection of the pH and counterion concentrations of the load, wash, and elution steps. Time and material constraints associated with operating laboratory columns often preclude evaluating more than 20–50 conditions during early stages of process development. To overcome this limitation, a high‐throughput screening (HTS) system employing a robotic liquid handling system and 96‐well filterplates was used to evaluate various operating conditions for IEX steps for monoclonal antibody (mAb) purification. A screening study for an adsorptive cation‐exchange step evaluated eight different resins. Sodium chloride concentrations defining the operating boundaries of product binding and elution were established at four different pH levels for each resin. Adsorption isotherms were measured for 24 different pH and salt combinations for a single resin. An anion‐exchange flowthrough step was then examined, generating data on mAb adsorption for 48 different combinations of pH and counterion concentration for three different resins. The mAb partition coefficients were calculated and used to estimate the characteristic charge of the resin–protein interaction. Host cell protein and residual Protein A impurity levels were also measured, providing information on selectivity within this operating window. The HTS system shows promise for accelerating process development of IEX steps, enabling rapid acquisition of large datasets addressing the performance of the chromatography step under many different operating conditions. Biotechnol. Bioeng. 2008;100: 950–963. © 2008 Wiley Periodicals, Inc.
Just working with the cellular machine
Authors: Cardoso Fernanda Serpa , Dumpel Renata , da Silva Luisa B. Gomes , Rodrigues Carlos R. , Santos Dilvani O. , Cabral Lucio Mendes , Castro Helena C. 
Published: March 2008

AbstractMolecular biology is a difficult comprehension subject due to its high complexity, thus requiring new teaching approaches. Herein, we developed an interdisciplinary board game involving the human immune system response against a bacterial infection for teaching molecular biology at high school. Initially, we created a database with several questions and a game story that invites the students for helping the human immunological system to produce antibodies (IgG) and fight back a pathogenic bacterium second‐time invasion. The game involves answering questions completing the game board in which the antibodies “are synthesized” through the molecular biology process. At the end, a problem‐based learning approach is used, and a last question is raised about proteins. Biology teachers and high school students evaluated the game and considered it an easy and interesting tool for teaching the theme. An increase of about 5–30% in answering molecular biology questions revealed that the game improves learning and induced a more engaged and proactive learning profile in the high school students.
Problem‐solving test: RNA and protein synthesis in bacteriophage‐infected E. coli cells
Authors: Szeberényi József 
Published: March 2008

AbstractTerms to be familiar with before you start to solve the test: Bacteriophage, E. coli, template, translation, density labeling, radioactive labeling, ribosomes, ribosomal fraction, ribosomal subunits, cesium chloride density gradient centrifugation, sucrose density gradient centrifugation, ribosomal RNA (rRNA), messenger RNA (mRNA).
Ludwik Maurycy Hirschfeld (1814–1876)
Authors: Reymond Jerzy , Gielecki Jerzy St. , Żurada Anna 
Published: March 2008

AbstractIt is rare to encounter exceptional individuals such as Ludwik Maurycy Hirschfeld. He was born into poverty and early on discovered his passion for medicine, particularly anatomy. His life is a testament to what pure human determination can achieve. He overcame societal and financial obstacles, ultimately becoming a physician, anatomist, and scientist. In 1834, Hirshfeld left Poland for France. His first exposure to medical anatomy came while under the direction of the great anatomist Professor Bourgery at École Pratique de Médicine. In 1848, he earned his degree in medicine and published his work “Des injections capillaires.” He coupled his love of anatomy with teaching and research. Hirschfeld's skills, as a dissector, enabled him to prepare specimens for illustration, which produced some of the anatomy atlases of modern times. “The Descriptive Anatomy of the Human Body” is one of his most influential works. Dr. Hirschfeld pioneered the initial illustrations of the meninges of brain. There are many anatomical structures named after him, including Hirschfeld's nerves and anastomoses. Hirshfeld remained as a professor until 1875. His death in 1876 was a great loss to the scientific community. His scientific accomplishments were astounding but he should also be remembered as a great humanitarian, an individual who offered medical treatment to the poor, and who strived to instill in his students a passion for anatomy. Clin. Anat. 21: 225–232, 2008. © 2008 Wiley‐Liss, Inc.
Selenium Compounds and Selenoproteins in Cancer
Authors: Brigelius‐Flohé Regina 
Published: March 2008

AbstractAn adequate selenium (Se) status has for long been considered to prevent the development of various forms of cancer. However, underlying molecular mechanisms remained unknown. In mammals, selenium exerts its functions as selenocysteine incorporated into selenoproteins. Therefore, Se compounds can either act as Se source for selenoproteins or, depending on their chemical forms, in distinct ways. Most potent chemopreventive effects have been attributed to compounds in which the Se moiety is methylated. These compounds are able to induce phase 2 enzymes which are involved in the cellular defense system that is regulated by the Nrf2 transcription factor. Selenoproteins best studied in cancer development are members of the glutathione peroxidase (GPx) and thioredoxin reductase (TrxR) family. In various cancer cells and tissues, GPx2 and/or TrxR1 are up‐regulated. Interestingly, both enzymes are targets of Nrf2. An enhanced expression of these enzymes may represent a mechanism to counteract carcinogenic pathways. They may, however, also provide a selective advantage for pre‐existing tumor cells in guaranteeing survival and continuous proliferation.
Biochemistry of Selenium‐Derivatized Naturally Occurring and Unnatural Nucleic Acids
Authors: Caton‐Williams Julianne , Huang Zhen 
Published: March 2008

AbstractSelenium (Se) can provide unique biochemical and biological functions, and properties to macromolecules, including protein and RNA. Although Se has not yet been found in DNA, identification of the presence of Se in natural tRNAs has led to discovery of the naturally occurring 2‐selenouridine and 5‐[(methylamino)methyl]‐2‐selenouridine (mnm5se2U). The Se‐atoms at C(2) of the modified uridines are introduced by 2‐selenouridine synthase via displacement of the S‐atoms in the corresponding 2‐thiouridine nucleotides of the tRNAs, and selenophosphate is used as the Se donor. The research indicated that mnm5se2U is located at the first or wobble position of the anticodons in several bacterial tRNAs, including tRNALys, tRNAGlu, and tRNAGln. The 2‐seleno functionality on this modified nucleotide probably improves the translation accuracy and/or efficiency. These observations in vivo suggest that the presence of Se can provide natural RNAs with useful properties to better function and survival. To further investigate the biochemical and structural properties of Se‐derivatized nucleic acids (SeNA), we have pioneered chemical and enzymatic synthesis of Se‐derivatized nucleic acids, and introduced Se into both RNA and DNA at a variety of positions by atom‐specific replacement of oxygen. This review outlines the recent advancements in chemical and biochemical syntheses, and studies of SeNAs, and their potential applications in structural and functional investigation of nucleic acids and their protein complexes.
A New Meroterpenoid Pigment from the Basidiomycete Albatrellus confluens
Authors: Yang Xiao‐Long , Qin Cheng , Wang Fei , Dong Ze‐Jun , Liu Ji‐Kai 
Published: March 2008

AbstractA new farnesyl phenol named (+)‐(R)‐grifolinone C (1) has been isolated from the fruiting bodies of the basidiomycete Albatrellus confluens. (+)‐(R)‐Grifolinone C (1), a dimeric meroterpenoid, is accompanied by albatrellin (2), grifolinone B (3), grifolin (4), and grifolinone A (5). Albatrellin (2) exhibited cytotoxic activity against HepG2 human lung carcinoma cells with IC50 value of 1.55 μg ml−1. The structures were established on the basis of spectral evidence (IR, 1D‐ and 2D‐NMR, and MS analyses).
Recombinant Whole‐Cell Mediated Baeyer–Villiger Oxidation of Perhydropyran‐Type Ketones
Authors: Mihovilovic Marko D. , Grötzl Birgit , Kandioller Wolfgang , Muskotál Adél , Snajdrova Radka , Rudroff Florian , Spreitzer Helmut 
Published: March 2008

AbstractRecombinant Escherichia coli cells expressing eight Baeyer–Villiger monooxygenases of bacterial origin have been utilized to oxidize prochiral heterocyclic ketones containing a pyran ring system. Within the biotransformation, two stereogenic centers were introduced with high control of enantioselectivity. The chemoselectivity of the enzymatic reaction was found to be high in favor of the Baeyer–Villiger process when using substituted ketone precursors incorporating functional groups labile to oxidation. A significantly different behavior was observed for two groups of monooxygenases with respect to substrate acceptance, which is consistent with our previous classification into two enzyme clusters.