bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synergistic reinforcement of nanoclay and carbon black in natural rubber
Authors: Qu Liangliang , Huang Guangsu , Zhang Peng , Nie Yijing , Weng Gengsheng , Wu Jinrong 
Published: June 2010

AbstractThe synergistic reinforcement of nanoclay (NC) and carbon black (CB) in natural rubber (NR) has not been much studied. Therefore, the reinforcement mechanism was probed using synchrotron wide‐angle X‐ray diffraction and transmission electron microscopy (TEM) observation and analyzed in terms of tube model theory. A synergistic effect in reinforcement between NC and CB was proved by the marked enhancement in tensile strength from 11.4 MPa for neat NR to 28.2 MPa for NR nanocomposite with 5 wt% NC and 20 wt% CB. From a study of crystallization under deformation it was found that crystallization plays a less important role in the reinforcement of NR/NC/CB. Analysis using tube model theory provided more evidence for the synergistic effect. NR containing a combination of NC and CB exhibited an increase of topological tube‐like constraints in comparison with NR/CB. That is to say, in NR/NC/CB nanocomposites, a CB–NC local filler network, as indicated by TEM images, induced a more entangled structure in which mobility of rubber chains was hindered for lateral fluctuations by the presence of neighboring chains. The synergistic reinforcement of NC and CB in NR/NC/CB nanocomposites can be reasonably understood as due to the formation CB–NC local filler networks. Copyright © 2010 Society of Chemical Industry
Synthesis and characterization of polyesters based on 1,1,1‐[bis(4‐hydroxyphenyl)‐4′‐pentadecylphenyl]ethane
Authors: More Arvind S , Naik Parimal V , Kumbhar Kishor P , Wadgaonkar Prakash P 
Published: June 2010

AbstractAromatic polyesters are of considerable interest because of their excellent mechanical properties, chemical resistance and thermal stability. However, most aromatic polyesters are difficult to process due to their high glass transition temperatures coupled with their insolubility in common organic solvents. The present article describes a series of organosoluble polyesters and copolyesters based on 1,1,1‐[bis(4‐hydroxyphenyl)‐4′‐pentadecylphenyl]ethane. A series of new aromatic polyesters containing pendant pentadecyl chains was synthesized by interfacial polycondensation of 1,1,1‐[bis(4‐hydroxyphenyl)‐4′‐pentadecylphenyl]ethane with terephthalic acid chloride (TPC), isophthalic acid chloride (IPC) and a mixture of TPC and IPC. A series of copolyesters was synthesized from 4,4′‐isopropylidenediphenol with TPC by incorporating 1,1,1‐[bis(4‐hydroxyphenyl)‐4′‐pentadecylphenyl]ethane as a comonomer. Inherent viscosities of the polyesters and copolyesters were in the range 0.72–1.65 dL g−1 and number‐average molecular weights were in the range 18 170–87 220. The polyesters and copolyesters containing pendant pentadecyl chains dissolved readily in organic solvents such as chloroform, dichloromethane, pyridine and m‐cresol and could be cast into transparent, flexible and apparently tough films. Wide‐angle X‐ray diffraction data revealed the amorphous nature of the polyesters and copolyesters. The formation of loosely developed layered structure was observed due to the packing of pendant pentadecyl chains. The temperature at 10% weight loss, determined using thermogravimetric analysis in nitrogen atmosphere, of the polyesters and copolyesters containing pendant pentadecyl chains was in the range 400–460 °C. The polyesters and copolyesters exhibited glass transition temperatures in the range 63–82 °C and 177–183 °C, respectively. Copyright © 2010 Society of Chemical Industry
Niobium oxide solid catalyst: esterification of fatty acids and modeling for biodiesel production
Authors: de Araújo Gonçalves Jussara , Ramos André Luis Dantas , Rocha Layla L. L. , Domingos Anderson Kurunczi , Monteiro Robson S. , Peres José Sotolongo , Furtado Nelson C. , Taft Carlton A. , Aranda Donato A. G. 
Published: June 2010

AbstractBiodiesel can be obtained from fatty acid raw materials through esterification. The reactivity of lauric, palmitic, stearic, oleic, and linoleic fatty acids with methanol using powdered niobic acid as a heterogeneous catalyst was investigated in this work, both experimentally (in a batch reactor) and theoretically. A 23 experimental design was used, with methanol/fatty acid molar ratio, catalyst concentration, and temperature as main factors. An empirical model demonstrated that temperature is the most important variable. Fourteen heterogeneous and 56 homogeneous‐like kinetic models were tested. A homogeneous‐like model considering zero order for all species and inhibition by water was the most adequate for experiments without catalyst. A homogeneous‐like model considering a second‐order reaction in relation to the fatty acid and no water inhibition was the most adequate for niobic acid catalyzed reaction. Molecular modeling confirmed the experimental results showing that the reactivity is directly related to the increase of unsaturated bonds and the reduction of carbon chain length. The polarity of the fatty acid is determinant in the reactivity. At the molecular level, reaction occurs between the HOMO orbital of methanol and LUMO orbitals of fatty acids and reactivity is higher when the energy difference between these orbitals is lower. Copyright © 2010 John Wiley & Sons, Ltd.
The internal thioester and the covalent binding properties of the complement proteins C3 and C4
Authors: Law S. K. Alex , Dodds Alister W. 
Published: June 2010

AbstractThe covalent binding of complement components C3 and C4 is critical for their activities. This reaction is made possible by the presence of an internal thioester in the native protein. Upon activation, which involves a conformational change initiated by the cleavage of a single peptide bond, the thioester becomes available to react with molecules with nucleophilic groups. This description is probably sufficient to account for the binding of the C4A isotype of human C4 to amino nucleophiles. The binding of the C4B isotype, and most likely C3, to hydroxyl nucleophiles, however, involves a histidine residue, which attacks the thioester to form an intramolecular acyl‐imidazole bond. The released thiolate anion then acts as a base to catalyze the binding of hydroxyl nucleophiles, including water, to the acyl function. This mechanism allows the complement proteins to bind to the hydroxyl groups of carbohydrates found on all biological surfaces, including the components of bacterial cell walls. In addition, the fast hydrolysis of the thioester provides a means to contain this very damaging reaction to the immediate proximity of the site of activation.
1,25‐dihydroxyvitamin D3 and PI3K/AKT inhibitors synergistically inhibit growth and induce senescence in prostate cancer cells
Authors: Axanova Linara S. , Chen Yong Q. , McCoy Thomas , Sui Guangchao , Cramer Scott D. 
Published: June 2010

AbstractBACKGROUND1‐Alpha, 25‐dihydroxyvitamin D3 (1,25(OH)2D3) inhibits proliferation of multiple cancer cell types including prostate cells and upregulates p21 and/or p27, while loss of Pten and PI3K/AKT activation stimulates survival and downregulates p21 and p27. We hypothesized that inhibition of the PI3K/AKT pathway synergizes with the antiproliferative signaling of 1,25(OH)2D3.METHODSViability, cell cycle and senescence of cells were evaluated upon combinational treatment with 1,25(OH)2D3 and pharmacological PI3K/AKT inhibitors.RESULTSPharmacological inhibitors of PI3K or Akt and 1,25(OH)2D3 synergistically inhibited growth of DU145, LNCaP, primary human prostate cancer cell strains and Pten null mouse prostatic epithelial cells (MPEC). The inhibitors used included API‐2 (Triciribine) and GSK690693 which are currently in clinical trials for treatment of cancer. A novel mechanism for antiproliferative effects of 1,25(OH)2D3 in prostate cells, induction of senescence, was discovered. Combination of 1,25(OH)2D3 and AKT inhibitor cooperated to induce G1 arrest, senescence, and p21 levels in prostate cancer cells. As AKT is commonly activated by PTEN loss, we evaluated the role of Pten in responsiveness to 1,25(OH)2D3 using shRNA knockdown and by in vitro knockout of Pten. MPEC that lost Pten expression remained sensitive to the antiproliferative action of 1,25(OH)2D3, and showed higher degree of synergism between AKT inhibitor and 1,25(OH)2D3 compared to Pten‐expressing counterparts.CONCLUSIONSThese findings provide the rationale for the development of therapies utilizing 1,25(OH)2D3 or its analogs combined with inhibition of PI3K/AKT for the treatment of prostate cancer. Prostate 70: 1658–1671, 2010. © 2010 Wiley‐Liss, Inc.
Inhibition of angiopoietin‐2 in LuCaP 23.1 prostate cancer tumors decreases tumor growth and viability
Authors: Morrissey Colm , Dowell Alex , Koreckij Theodore D. , Nguyen Holly , Lakely Bryce , Fanslow William C. , True Lawrence D. , Corey Eva , Vessella Robert L. 
Published: June 2010

AbstractBACKGROUNDAngiopoietin‐2 is expressed in prostate cancer (PCa) bone, liver, and lymph node metastases, whereas, its competitor angiopoietin‐1 has limited expression in these tissues. Therefore, we hypothesized that the inhibition of angiopoietin‐2 activity in PCa will impede angiogenesis, tumor growth, and alter bone response in vivo.METHODSTo test our hypothesis we used L1‐10, a peptide‐Fc fusion that inhibits interactions between angiopoietin‐2 and its receptor tie2. We blocked angiopoietin‐2 activity using L1‐10 in established subcutaneous and intra‐tibial LuCaP 23.1 xenografts. We then determined the effect of L1‐10 on survival, tumor growth, serum PSA, proliferation, microvessel density, and angiogenesis‐associated gene expression in subcutaneous tumors. We also determined serum PSA, tumor area, and bone response in intra‐tibial tumors.RESULTSThe administration of L1‐10 decreased tumor volume and serum PSA, and increased survival in SCID mice bearing subcutaneous LuCaP 23.1 tumors. Histomorphometric analysis, showed a further significant decrease in tumor epithelial area within the L1‐10 treated LuCaP 23.1 subcutaneous tumors (P = 0.0063). There was also a significant decrease in cell proliferation (P = 0.012), microvessel density (P = 0.012), and a significant increase in ANGPT‐2 and HIF‐1α mRNA expression (P ≤ 0.05) associated with L1‐10 treatment. Alternatively, in LuCaP 23.1 intra‐tibial tumors L1‐10 treatment did not significantly change serum PSA, tumor area or bone response.CONCLUSIONSOur results demonstrate that inhibiting angiopoietin‐2 activity impedes angiogenesis and growth of LuCaP 23.1 PCa xenografts. Based on these data, we hypothesize that angiopoietin‐2 inhibition in combination with other therapies may represent a potential therapy for patients with metastatic disease. Prostate 70: 1799–1808, 2010. © 2010 Wiley‐Liss, Inc.
Cross‐resistance and possible mechanisms of chlorpyrifos resistance in Laodelphax striatellus (Fallén)
Authors: Wang Lihua , Zhang Yueliang , Han Zhaojun , Liu Yanhe , Fang Jichao 
Published: June 2010

AbstractBACKGROUND: Laodelphax striatellus (Fallén) is a major pest of cultivated rice and is commonly controlled in China with the organophosphate insecticides. To develop a better resistance management strategy, a chlorpyrifos‐resistant strain of L. striatellus was selected in the laboratory, and its cross‐resistance to other insecticides and possible mechanisms of the chlorpyrifos resistance were investigated.RESULTS: After 25 generations of selection with chlorpyrifos, the selected strain of L. striatellus developed 188‐fold resistance to chlorpyrifos in comparison with the susceptible strain, and showed 14‐ and 1.6‐fold cross‐resistance to dichlorvos and thiamethoxam respectively. There was no apparent cross‐resistance to abamectin. Chlorpyrifos was synergised by the inhibitor triphenyl phosphate; the carboxylesterase synergistic ratio was 3.8 for the selected strain, but only 0.92 for the susceptible strain. The carboxylesterase activity of the selected strain was approximately 4 times that of the susceptible strain, whereas there was no significant change in the activities of alkaline phosphatase, acid phosphatase, glutathione S‐transferase and cytochrome P450 monooxygenase between the strains. The Michaelis constant of acetylcholinesterase, maximum velocity of acetylcholinesterase and median inhibitory concentration of chlorpyrifos‐oxon on acetylcholinesterase were 1.7, 2.5 and 5 times higher respectively in the selected strain.CONCLUSION: The high cross‐resistance to the organophosphate dichlorvos in the chlorpyrifos‐resistant strain suggests that other non‐organophosphate insecticides would be necessary to counter resistance, should it arise in the field. Enhanced activities of carboxylesterase and the acetylcholinesterase insensitivity appear to be important mechanisms for chlorpyrifos resistance in L. striatellus. Copyright © 2010 Society of Chemical Industry
Syntheses and activities of backbone‐side chain cyclic octapeptide ligands with N‐functionalized phosphotyrosine for the N‐terminal SH2‐domain of the protein tyrosine phosphatase SHP‐1
Authors: Zoda Mohammad Safa , Zacharias Martin , Reissmann Siegmund 
Published: June 2010

AbstractThe protein tyrosine phosphatase SHP‐1 plays an important role in many physiological and pathophysiological processes. This phosphatase is activated through binding of ligands to its SH2‐domains, mainly to the N‐terminal one. Based on a theoretical docking model, backbone‐to‐side chain cyclized octapeptides were designed as ligands. Assembly of such modelled structures required the synthesis of N‐functionalized tyrosine derivatives and their incorporation into the sequence. Because of difficulties encountered in the condensation of N‐protected amino acids to the N‐alkylated tyrosine‐peptide we synthesized and used preformed dipeptide building units. As all attempts to obtain phosphorylated dipeptide units failed, the syntheses had to be performed with a free phenolic function. Use of different N‐alkyl or cycloalkyl residues in the N‐functionalized side chains allowed to investigate the effect of ring size, flexibility and hydrophobicity of formed lactam bridges on stimulatory activity. All tested linear and cyclic octapeptides stimulate the phosphatase activity of SHP‐1. Stimulatory activities of cyclic ligands increase with the chain length of the lactam bridges resulting in increased flexibility and better entropic preformation of the binding conformation. The strong activity of some cyclic octapeptides supports the modelled structure. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.
Electron‐beam‐induced fabrication of metal‐containing nanostructures
Authors: Kislov N. A. , Khodos I. I. , Ivanov E. D. , Barthel J. 
Published: June 2010

AbstractAn experimental system based on a transmission electron microscope JEM‐100CX has been developed for electron beam‐induced chemical vapor deposition. Direct electron beam‐induced growth of nanometer‐wide self‐supporting rods has been performed inside the microscope operating in scanning mode by decomposition of carbonyls of chromium Cr(CO)6, tungsten W(CO)6, and rhenium Re2(CO)10. In situ phase and structure transformations under annealing inside the microscope column were studied. Nanoscale rods and strips grown from rhenium carbonyl are of special interest because, after annealing, they consist of a single pure rhenium phase. The described method of metallic nanoelements fabrication enables us to produce highly conductive nanowires and tips for application in nanoelectronics, emission electronics, and scanning tunneling microscopy.
Advantages of backscatter electron imaging scanning electron microscopy for intracellular localization of cardiac analytes by gold conjugated antibody
Authors: Lea Peter. , Lee Lilian M. Y. , WeiShi Qin. , Takahashi Miyoko , Youn Woo , Jackowski George 
Published: June 2010

AbstractMyoglobin and myosin light chain1 (MLC1) are intracellular human cardiac marker proteins which are released as a consequence of ischemia. Human cardiomyocytes were isolated from fresh biopsies and also maintained for several passages in cell culture. The cardiomyocytes were fixed in 100% methanol at −20°C, and labeled. The immunolocalization of intracellular antigen by fluorescence conjugated imaging was compared with scanning electron microscopy (SEM) backscatter electron (BSE) imaging of gold conjugated antibody. Ultraviolet light microscopy showed the intracellular distribution of both proteins to be mainly in the nuclear envelope, the cytoplasm immediately surrounding the nucleus and along portions of the cell membrane. To confirm this observed distribution of myoglobin and MLC1, labeling was repeated with antimyoglobin and anti‐MLC1 monoclonal antibodies conjugated to colloidal gold particles. The advantage of colloidal gold labeling is that the intracellular antigen‐antibody complexes may be more precisely located because of the significant improvement in resolution provided by BSE imaging in the SEM. BSE imaging confirmed the presence and subsarcolemma localization of myoglobin in cardiomyocytes directly isolated from fresh biopsies. The distribution of colloidal gold‐conjugated antibodies did not coincide with the intracellular distribution of the two proteins in the cardiomyocytes grown in cell culture as indicated by immunofluorescence. A relatively random, intracellular gold particle distribution was confirmed by x‐ray microanalysis. BSE imaging resulted in consistent auto‐backscatter labeling patterns very similar to the labeling patterns obtained with immunofluorescent labeling. X‐ray microanalysis confirmed that these auto‐backscatter labeling patterns were formed by concentrations of intracellular phosphate. Sodium dodecyl sulfate‐polyacrylamide gel eletrophoresis (SDS‐PAGE) and subsequent Western blotting indicated that myoglobin and MLC1 were no longer present in detectable quantities in these cells after several passages. Polymerase chain reaction (PCR) amplification of mRNA for human myoglobin and cardiac MLC1 confirmed the absence of their transcripts. Electrophoretic analysis of proteins in cardiomyocytes grown in cell culture confirmed an increasing presence of alkaline phosphatase. Staining of this enzyme with 5–bromo‐4–chloro‐3–indolyl phosphate and nitroblue tetrazolium showed that alkaline phosphatase was distributed in the same intracellular pattern as the fluorescence conjugated antibody and the phosphate auto‐backscatter. These results indicate that high‐resolution backscatter SEM imaging may be used as necessary control to confirm fluorescence light microscope intracellular labeling of antigens.
Magnetic refinement of tips for magnetic force microscopy
Authors: Bauer P. , Bochem H. P. , Leinenbach P. , Memmert U. , Schelten J. 
Published: June 2010

AbstractSilicon cantilever probes with monolithically integrated tips are commercially available and are routinely used for atomic force microscopy (AFM). For such probes, amagnetic refinement of the silicon tip has been developed and results in a deposition of ferromagnetic material such as nickel or CrCoTa in the top area of the tip. The method consists of essentially three steps: (1) A broad‐area sputter deposition of a ferromagnetic material; (2) a selective electron beam‐induced carbon deposition at the top of the tip; (3) a broad‐area ion‐beam sputter etching, which removes the magnetic layer everywhere except underneath the carbon cap. The method allows to control the total amount and extension of the magnetic material left at the tip. It is applicable to all kinds of ferromagnetic materials which can be deposited as a thin layer by sputter deposition or evaporation. Experiments indicate that the method is reliable and improves the resolution of magnetic force microscopy (MFM). With such magnetically refined tips on silicon cantilevers, MFM measurements have been performed in contact mode as well as in dynamic and static noncontact modes. In this paper, the method for magnetic tip refinement is described and MFM measurements with these tips are presented.
Angioarchitecture of the terminal vascular system in inflammatory bowel disease—A comparative corrosion‐anatomic study
Authors: Busch C. , Gawad K. A. , Prenzel K. L. , Knoefel W. T. , Izbicki J. R. , Broelsch C. E. 
Published: June 2010

AbstractThe vascular origin of Crohn's disease (CD) and ulcerative colitis has been discussed but is poorly understood and investigated. A comparison of both diseases on the basis of the angioarchitecture had yet to be performed to investigate vascular morphology further and to evaluate its relevance for the etiology and differential diagnosis. The vascular system of 29 human colonic specimens of patients with CD (n=10), ulcerative colitis (n=11), and colon cancer (n=8), which were taken as controls, was perfused blood‐free immediately after resection. Corrosion casts were obtained by injection of Mercox Cl and consecutive digestion with potassium hydroxide. Casts were then cut into sections, sputter coated with gold, and examined in a blinded fashion by scanning electron microscopy. Normal intestine showed a typical honeycomb appearance, the mucosal capillary network was smooth and regular, and the subepithelial vascular plexus was supplied by regularly arranged arterioles. In CD, a partially intact capillary net with alterations, dominant collecting veins, and a characteristic pattern of diameter changes with narrow segments in the capillary bed was seen. In ulcerative colitis a disruption of the colonic vascular architecture was found. The capillarization was rarefied and irregular lumps of subepithelial capillary structures were observed. The morphology of the terminal vascular bed in inflammatory bowel disease in contrast to normal controls is uniquely described. The technique of injecting fresh, human specimens was applied for the first time. The homogeneity of vascular changes within each entity seems to allow a differentiation between CD and ulcerative colitis.
Key morphologic changes and DNA strand breaks in human lymphoid cells: Discriminating apoptosis from necrosis
Authors: Fairbairn Daryl W. , Walburger David K. , Fairbairn Joshua J. , O'Neill Kim L. 
Published: June 2010

AbstractApoptosis is an important form of physiologic cell death displayed by an enormous variety of tissues under divergent conditions. The recent attention toward apoptosis in virtually all aspects of modern biology indicates that rapid and accurate differentiation between apoptosis and necrotic death is of considerable interest. Apoptosis is distinguishable from necrosis on the basis of several criteria. In this study, we undertook to examine the effects of mild hyperthermia (43°C leading to apoptotic death) and severe hyperthermia (50°C leading to necrotic killing) on associated DNA fragmentation. Using laser scanning and fluorescent microscopic evaluation of DNA “comets” in the single cell gel assay, we compared necrotic and apoptotic DNA damage in a variety of human leukemia and lymphoma cell lines at the level of the individual cell. We show that necrotic cells do display detectable DNA damage. We confirm our preliminary report that comet “tail moment” is sufficient to distinguish between necrotic and apoptotic DNA damage, while comet tail length may confuse the two forms. We report that a recovery period is necessary for expression of increasing apoptotic but not necrotic DNA damage. We show that apoptosis increases with prolonged hyperthermia and confirm that the mode of death changes from apoptosis to necrosis with higher heat loads, producing a greater fraction of cells showing damage. In addition, we show that for necrotic cells, DNA tail moment reflects sensitivity to prolonged exposure without a concomitant change in tail length.