bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tetrafluoroethylene Copolymers with Sulfonyl Fluoride Pendants: Syntheses in Supercritical Carbon Dioxide, Polymerization Behaviors, and Properties
Authors: Xu Anhou , Zhao Junhong , Yuan Wang Zhang , Li Hong , Zhang Heng , Wang Li , Zhang Yongming 
Published: May 2011

AbstractCopolymerizations of tetrafluoroethylene (TFE) and perfluoro(3,6‐dioxa‐4‐methyl‐7‐octen)sulfonyl fluoride (PSVE) initiated by bis(perfluoro‐2‐n‐propoxypropionyl) peroxide in supercritical carbon dioxide are investigated. The reactivity ratios for TFE (rTFE) and PSVE (rPSVE) are calculated to be 7.85, 0.079 and 7.92, 0.087 according to Fineman–Ross and Kelen–Tudos methods, respectively. The glass transition temperatures of the copolymers increase with increasing in PSVE content. Comparison studies on above copolymers and another fluorinated sample prepared in emulsion show that the copolymers have comparable properties to the fluorinated one, thus offering an economic way to improve the properties of TFE–PSVE copolymers for their applications in diverse fields. magnified image
Simple and Rapid Fabrication of Large‐Scale Polymer‐Immobilized Colloidal Crystals by Spray Coating
Authors: Ishii Masahiko , Narita Takeshi , Hayata Yuki , Nishimura Akira , Tachi Kazuyuki 
Published: May 2011

AbstractPolymer‐immobilized colloidal crystal films have been fabricated by conventional spray coating and UV curing of silica–acrylic monomer suspensions. Controlling both the viscosity of the suspensions and the wettability of substrates enabled colloidal crystal films with smooth surfaces and brilliant structural colors due to Bragg diffraction. The structural colors could be controlled by particle concentrations in addition to particle diameter. The wettability influenced the thickness of the coated film and it consequently affected the Bragg reflection intensity of the film. Silhouette figures were textured on a substrate having regions with different wettabilities by single spray coating. magnified image
Phantom Ring‐Closing Condensation Polymerization: Towards Antibacterial Oligoguanidines
Authors: Mattheis Claudia , Schwarzer Martin C. , Frenking Gernot , Agarwal Seema 
Published: May 2011

AbstractThe first example of phantom ring‐closing condensation polymerization for the synthesis of oligoguanidines is presented. A new oligoguanidine with a ring structure was achieved in one step by the condensation reaction of a triamine, like diethylenetriamine, with guanidine hydrochloride. The condensation reaction proceeded by selective ring‐closure towards the formation of five‐membered rings in the oligomer backbone. The resulting polymer repeat unit structure was different from the starting monomers (phantom polymer) and was formed by elimination of three molecules of ammonia per repeat unit. The inter‐, intra‐, and inter‐molecular reaction sequences led to the new structure as proved by different spectroscopic techniques (atmospheric pressure chemical‐ionization mass spectrometry, and one‐dimensional and two‐dimensional homo‐ and heteronuclear correlation NMR experiments) as well as supported by quantum chemical investigations. Preliminary results regarding antibacterial use of the resulting oligoguanidine were also promising and showed its effect within 15–30 min as an antibacterial material. magnified image
Silibinin inhibits the invasion and migration of renal carcinoma 786‐O cells in vitro, inhibits the growth of xenografts in vivo and enhances chemosensitivity to 5‐fluorouracil and paclitaxel
Authors: Chang Horng‐Rong , Chen Pei‐Ni , Yang Shun‐Fa , Sun Ying‐Sui , Wu Sheng‐Wen , Hung Tung‐Wei , Lian Jong‐Da , Chu Shu‐Chen , Hsieh Yih‐Shou 
Published: May 2011

AbstractSilibinin is a flavonoid antioxidant that is widely used for its anti‐hepatotoxic properties. It exerts a dose‐dependent inhibition on the invasion and migration of 786‐O renal cell carcinoma (RCC) cells in the absence of cytotoxicity. 786‐O cells were treated with silibinin at various concentrations, up to 50 µM, for a defined period and then subjected to gelatin zymography, casein zymography, and Western blot to investigate the impacts of silibinin on metalloproteinase (MMP) ‐2, ‐9, urokinase plasminogen activator (u‐PA), and MAPK pathway signaling proteins, respectively. The results showed that silibinin decreased MMP‐2, MMP‐9, u‐PA, p‐p38, and p‐Erk1/2 expressions in a concentration‐dependent manner. The reduced expressions of MMP‐2 and u‐PA, as well as inhibition of cell invasion were obtained in the cultures pre‐treated with PD98059 (Erk1/2 inhibitor) and SB203580 (p38 inhibitor). An in vivo anti‐tumor study with a nude mice xenograft model by a subcutaneous inoculation of 786‐O cells demonstrated small solid tumors after eight days following cell inoculation. There was a 70.1% reduction in tumor volume and 69.7% reduction in tumor weight by silibinin feeding on day 44, compared to those of controls. Moreover, combination treatment with silibinin and 5‐fluorouracil, paclitaxel, vinblastine, or RAD‐001 enhanced the chemosensitivity of 5‐fluorouracil and paclitaxel. In conclusion, silibinin inhibits the invasion and migration of 786‐O cells in vitro, inhibits the growth of xenografts in vivo, and enhances chemosensitivity to 5‐fluorouracil and paclitaxel. © 2011 Wiley‐Liss, Inc.
Quality of life in young‐ compared with late‐onset Parkinson's disease
Authors: Knipe M. Duleeka W. , Wickremaratchi Mirdhu M. , Wyatt‐Haines Emma , Morris Huw R. , Ben‐Shlomo Yoav 
Published: May 2011

AbstractThe impact of Parkinson's disease on quality of life may vary depending on age at onset. We investigated the effect of age at onset on quality of life in a large Parkinson's disease population (n = 426) using a disease‐specific rating scale (PDQ‐39) and with careful adjustment for confounding and intermediary factors. We also explored the relationship between depression and excessive daytime sleepiness by age at onset and compared this with the general population. We found that a younger age at onset was significantly associated with worse overall quality of life scores (odds ratio, 2.66; 95% confidence interval, 1.39–5.09; P = .003), but this was attenuated by adjustment for depression as an intermediary factor (odds ratio, 1.86; 95% confidence interval, 0.84–4.11; P = .13). Younger onset was also a risk factor for poor emotional well‐being independent of depression status. Risk of depression and excessive daytime sleepiness were elevated in patients with Parkinson's disease compared with controls (odds ratio, 2.99; 95% confidence interval, 1.93–4.65; P < .001; and odds ratio, 3.84; 95% confidence interval, 2.56–5.75; P < .001, respectively), with similar findings seen in both early‐ and late‐onset groups. Our study highlights the need for accurate diagnosis and treatment of depression in younger‐onset patients in order to improve quality of life. © 2011 Movement Disorder Society
Sperm storage in the female reproductive tract of Scotophilus heathii: Role of androgen
Authors: Roy Vikas Kumar , Krishna Amitabh 
Published: May 2011

AbstractThe aim of the present study was to investigate the mechanism of androgen‐mediated, prolonged sperm‐storage in the female reproductive tract of the bat, Scotophilus heathii. The bat treated in vivo with flutamide, an androgen antagonist, showed loss of spermatozoa at the storage site, utero‐tubal junction. Immunocytochemistry and Western blot analysis revealed the presence of increased expression of Bcl2 in the epithelial cell lining of the utero‐tubal junction during the period of sperm‐storage. Treatment with testosterone in vitro caused a significant dose‐dependent increase in expression of the survival factor Bcl2, whereas treatment with flutamide together with testosterone caused a significant decline in Bcl2 in the utero‐tubal junction of S. heathii. Together with the expression of Bcl2, the utero‐tubal junction also expresses the death signal, caspase3. Expression of caspase3 decreased during January, but increased in February during the late stage of sperm storage. Androgen stimulated Bcl2 synthesis in the utero‐tubal junction via the non‐genomic MAP kinase signaling pathway. In conclusion, this study suggests that androgen promotes sperm storage in S. heathii by stimulating the survival factor Bcl2 in the utero‐tubal junction. It is further hypothesized that a balance between the survival factor, Bcl2, and the death signal, caspase3, determines the duration of sperm storage in S. heathii. Mol. Reprod. Dev. 78:477–487, 2011. © 2011 Wiley‐Liss, Inc.
Full‐length phrenic nerve transfer as the treatment for brachial plexus avulsion injury to restore wrist and finger extension
Authors: Lin Haodong , Hou Chunlin , Chen Desong 
Published: May 2011

AbstractIntroduction: The functional restoration of wrist and finger extension after complete brachial plexus avulsion injury remains an unsolved problem. We conducted a prospective study to elucidate a new method for resolving this injury. Methods: Six patients with complete brachial plexus avulsion injury underwent a new surgical procedure in which the full‐length phrenic nerve was transferred to the medial portion of the radial nerve at the level of the latissimus dorsi insertion via endoscopic thoracic surgery. Results: In 5 patients, extensor carpi ulnaris and extensor carpi radialis strength recovered to Medical Research Council grade ≥M3, and in 4 patients extensor digitorum strength recovered to ≥M3. Conclusions: Neurotization of phrenic nerve to the medial portion of the radial nerve at the level of latissimus dorsi insertion is a feasible means of restoring wrist and finger extension in cases of complete brachial plexus avulsion injury. Muscle Nerve 45: 39–42, 2012
Muscle function in monozygotic female twin pairs discordant for hormone replacement therapy
Authors: Finni Taija , Noorkoiv Marika , Pöllänen Eija , Ronkainen Paula H.A. , Alén Markku , Kaprio Jaakko , Kovanen Vuokko , Sipilä Sarianna 
Published: May 2011

AbstractIntroduction: Postmenopausal monozygotic twin pairs discordant for hormone replacement therapy (HRT) provide an advantageous study design controlling for genetic background for elucidating the relationships between aging, sex hormone levels, muscle strength, contractile capacity, and fatigability. Methods: Thirteen postmenopausal monozygotic twin pairs discordant for HRT were measured for maximal voluntary torque (MVC) and twitch characteristics using electrical stimulation before and after intermittent dynamic plantarflexor exercise until exhaustion. Results: Peak twitch torque was 32% higher in HRT users than in their non‐HRT, genetically identical sisters (P = 0.002), but MVC did not differ. There were no differences in the activation level or twitch time characteristics between the co‐twins. Fatigue caused decreases in MVC (P = 0.001), twitch torque (P = 0.001), time to peak (P = 0.013), and half‐relaxation time (P = 0.001) similarly in HRT users and non–HRT users. Conclusion: In early postmenopausal women, involuntary but not voluntary force‐generating mechanisms of the plantarflexors are augmented by the use of HRT. Muscle Nerve, 2011
Membrane color and gas permeability of 6FDA‐TeMPD polyimide membranes prepared with various membrane preparation protocols
Authors: Kanehashi Shinji , Sato Shuichi , Nagai Kazukiyo 
Published: May 2011

AbstractThe relations among polyimide membrane colors, their gas transport and separation properties, and their fluorescence spectra were systematically investigated using fluorine‐containing aromatic polyimide, 6FDA‐TeMPD {[4,4‐(hexafluoroisopropylidene) diphthalic anhydride] [(6FDA)‐2,3,5,6‐tetramethyl‐1,4‐phenylene‐diamine (TeMPD)]}, which was used in electronic device and gas separation materials. Different molecular ordering structures of 6FDA‐TeMPD polyimides were prepared by controlling kinds of casting solvents and dry conditions. This difference was based on the effect of charge transfer (CT) interaction formed by π electrons of ring structures in polyimide. Membrane color measured using spectrophotometer determined colors as intrinsic parameters without sample collection. The permeability coefficients of oxygen and nitrogen of the 6FDA‐TeMPD polyimide membranes were correlated with membrane color index parameters such as L*, a*, b*, and ΔE*, and fluorescence properties such as maximum peak emission wavelength λmax and intensity Imax, which reflect molecular ordering affected by CT interaction in polyimide membranes. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Experimental identification of the deformation mechanisms during sintering of cold compacted polytetrafluoroethylene powders
Authors: Canto Rodrigo Bresciani , Schmitt Nicolas , De Carvalho Jonas , Billardon René 
Published: May 2011

AbstractThe influence of the cooling rate after melting on the crystalline weight fraction of pure poly(tetrafluoroethylene) (PTFE) was derived from differential scanning calorimetry tests. Specimens made of pure or filled PTFE were manufactured by isostatic or constrained uniaxial cold pressing, up to different values of the porosity. Dilatometry tests were carried out on these specimens while imposing various heating–cooling treatments. The deformations recorded during these tests strongly depend on the mode and level of compaction. The original procedures presented, herein, made it possible to identify that these macroscopic deformations, which are strongly anisotropic for uniaxially pressed specimens, result from the combination of different independent mechanisms. The mechanisms that were distinguished are reversible thermal expansion, void closure, crystalline to amorphous and vice versa transformations, and recovery, which were not observed for isostatically pressed specimens. It was also shown that, after being subjected to a standard sintering treatment, anisotropically pressed specimens still exhibit anisotropic crystallization strains. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Use of seed layers for structure, optical, and electronic transport measurements on microcrystalline silicon on glass
Authors: Ross C. , Mai Y. , Carius R. , Finger F. 
Published: May 2011

AbstractA detailed structural analysis is provided by which the benefits of thin undoped ‘seed layers’ for the preparation of microcrystalline silicon on glass for material characterization are demonstrated. Raman spectroscopy and photothermal deflection spectroscopy (PDS) results reveal that ‘seed layers’ are not only effective for the growth of structurally homogenous films and for an extension of the range of deposition parameters in which highly crystalline material is grown, but also allow for preparing material on glass with properties very close to that of functional layers in thin film solar cells. Films which have successfully been tailored in this way are characterized with respect to electrical conductivity and optical absorption. Regarding conductivity, hydrogenated microcrystalline silicon material grown on a ‘seed layer’ exhibits a structure‐dependent behaviour which is very similar to that observed for material grown on bare glass. Regarding optical absorption spectra, residual interference fringes, which indicate structural non‐uniformities, can be successfully removed by means of ‘seed layers’. As a result, more information is obtainable from PDS, and the data gained in this way are in good agreement with Raman spectroscopy results. Copyright © 2011 John Wiley & Sons, Ltd.
Context‐dependent resistance to proteolysis of intrinsically disordered proteins
Authors: Suskiewicz Marcin J. , Sussman Joel L. , Silman Israel , Shaul Yosef 
Published: May 2011

AbstractIntrinsically disordered proteins (IDPs), also known as intrinsically unstructured proteins (IUPs), lack a well‐defined 3D structure in vitro and, in some cases, also in vivo. Here, we discuss the question of proteolytic sensitivity of IDPs, with a view to better explaining their in vivo characteristics. After an initial assessment of the status of IDPs in vivo, we briefly survey the intracellular proteolytic systems. Subsequently, we discuss the evidence for IDPs being inherently sensitive to proteolysis. Such sensitivity would not, however, result in enhanced degradation if the protease‐sensitive sites were sequestered. Accordingly, IDP access to and degradation by the proteasome, the major proteolytic complex within eukaryotic cells, are discussed in detail. The emerging picture appears to be that IDPs are inherently sensitive to proteasomal degradation along the lines of the “degradation by default” model. However, available data sets of intracellular protein half‐lives suggest that intrinsic disorder does not imply a significantly shorter half‐life. We assess the power of available systemic half‐life measurements, but also discuss possible mechanisms that could protect IDPs from intracellular degradation. Finally, we discuss the relevance of the proteolytic sensitivity of IDPs to their function and evolution.
Crystal structure of the bifunctional tRNA modification enzyme MnmC from Escherichia coli
Authors: Kitamura Aya , Sengoku Toru , Nishimoto Madoka , Yokoyama Shigeyuki , Bessho Yoshitaka 
Published: May 2011

AbstractPost‐transcriptional modifications of bases within the transfer RNAs (tRNA) anticodon significantly affect the decoding system. In bacteria and eukaryotes, uridines at the wobble position (U34) of some tRNAs are modified to 5‐methyluridine derivatives (xm5U). These xm5U34‐containing tRNAs read codons ending with A or G, whereas tRNAs with the unmodified U34 are able to read all four synonymous codons of a family box. In Escherichia coli (E.coli), the bifunctional enzyme MnmC catalyzes the two consecutive reactions that convert 5‐carboxymethylaminomethyl uridine (cmnm5U) to 5‐methylaminomethyl uridine (mnm5U). The C‐terminal domain of MnmC (MnmC1) is responsible for the flavin adenine dinucleotide (FAD)‐dependent deacetylation of cmnm5U to 5‐aminomethyl uridine (nm5U), whereas the N‐terminal domain (MnmC2) catalyzes the subsequent S‐adenosyl‐L‐methionine‐dependent methylation of nm5U, leading to the final product, mnm5U34. Here, we determined the crystal structure of E.coli MnmC containing FAD, at 3.0 Å resolution. The structure of the MnmC1 domain can be classified in the FAD‐dependent glutathione reductase 2 structural family, including the glycine oxidase ThiO, whereas the MnmC2 domain adopts the canonical class I methyltransferase fold. A structural comparison with ThiO revealed the residues that may be involved in cmnm5U recognition, supporting previous mutational analyses. The catalytic sites of the two reactions are both surrounded by conserved basic residues for possible anticodon binding, and are located far away from each other, on opposite sides of the protein. These results suggest that, although the MnmC1 and MnmC2 domains are physically linked, they could catalyze the two consecutive reactions in a rather independent manner.
Selection and characterization of a 7‐mer peptide binding to divalent cations
Authors: Han Daeyoung , Huh Seong , Myung Heejoon 
Published: May 2011

AbstractA 7‐mer peptide (S‐T‐L‐P‐L‐P‐P) that bound to various divalent cations was selected from a phage display peptide library. Isothermal calorimetric analysis revealed that the peptide bound to Pb2+, Cd2+, Hg2+, and Cu2+. Through the use of CD studies, no secondary structural changes were observed for the peptide upon binding to divalent cations. Ala scanning mutant peptides bound to Hg2+ with a reduced affinity. However, no single substitution was shown to affect the overall affinity. We suggest that Pro residues chelate divalent cations, while the structure formed by the peptide is also important for the binding process. Copyright © 2011 European Peptide Society and John Wiley & Sons, Ltd.
Elastic properties and electronic structures of MgCe intermetallic compounds from first‐principles calculations
Authors: Yang Fang , Wang Ji‐Wei , Ke Jiang‐Ling , Pan Zheng‐Gui , Tang Bi‐Yu 
Published: May 2011

AbstractFirst‐principles calculations have been carried out to investigate the elastic properties and electronic structures of the main binary MgCe phases MgCe, Mg2Ce, and Mg3Ce. The optimized equilibrium lattice constants are in agreement with the available experimental values, and the structural stability of MgCe, Mg2Ce, and Mg3Ce is studied from the calculated heat of formation and cohesive energy. The elastic constants Cij of these phases are calculated; then the bulk modulus, shear modulus, Young's modulus, Cauchy pressure, and the ratio of bulk to shear modulus B/G are further investigated. The obtained results indicate that Mg2Ce has the best ductility and plasticity, while Mg3Ce is the hardest and the most brittle among the three MgCe phases. The density of states (DOSs) and charge density distribution of the MgCe phases are also calculated to reveal the underlying mechanism for the structural stability and elastic properties of these MgCe phases.
Microspheres manipulation system by patterned AlGaN/GaN 2DEG electrodes
Authors: Fu Junxue , Chen Kevin J 
Published: May 2011

AbstractA manipulation system utilizing the properties of two‐dimensional electron gas (2DEG) at the interface of AlGaN/GaN and dielectrophoresis (DEP) was investigated in this study. At an applied frequency ranging from 100 kHz to 1 MHz and a potential of 20 vpeak to peak, the positive and negative DEP of the microspheres were reported for the first time by the Fluorine ion patterned and parylene covered 2DEG. In addition, by simply switching the applied frequency between 100 kHz and 500 kHz, the microspheres could come onto or get off from 2DEG region of AlGaN/GaN surface. Thus, a promising sensing scheme was proposed by combining the manipulation with sensing properties of 2DEG. This manipulation system based on 2DEG will bring much benefit to sensor applications. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Blue LEDs – way to overcome efficiency droop
Authors: Zakheim Dmitry A. , Pavluchenko Alexey S. , Bauman Dmitry A. 
Published: May 2011

AbstractIn this paper we report on fabrication of high power InGaN based blue light emitting diodes (LEDs) with substantially suppressed efficiency droop. The key feature of proposed device is the utilization of short‐period superlattice in the active region of LED heterostructure. In this superlattice the GaN barriers between quantum wells (QWs) are transparent for tunnelling, thus enabling carrier delocalization in growth direction. This, in turn, leads to the reduction of carrier concentration at given pumping comparing to the standard LED heterostructure, where, usually, only one QW contributes to light emission. The reduction of carrier concentration results in substantial suppression of third order non‐radiative processes, such as Auger recombination, responsible for the efficiency droop at high pumping. As a result, the LED external efficiency at operating current 350 mA differs from its maximum value only by 7%. Also, fabricated LEDs demonstrate very good stability of spectral position of the emission line, the observed blue shift of electroluminescence being less than 1 nm at pumping up to 1000 mA. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)