bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hereditary hemochromatosis gene (HFE) variants are associated with birth weight and childhood leukemia risk
Authors: Dorak M. Tevfik , Mackay Rachel K. , Relton Caroline L. , Worwood Mark , Parker Louise , Hall Andrew G. 
Published: August 2009

AbstractBackgroundOur original studies reported an association between the iron‐metabolism gene HFE and risk of childhood acute lymphoblastic leukemia (ALL), and a birth weight association in ALL. Through its effect on cell proliferation, iron is involved in both fetal development and cancer. We hypothesize that HFE links higher infant birth weight with leukemia risk and that maternal HFE genotype modifies this association.ProcedureNine hundred ninety‐five infants and their mothers from the North Cumbria Community Genetics Project, and 163 incident childhood ALL cases from the Newcastle Haematology Biobank were genotyped for HFE, HAMP, TFRC variants and 21 genomic control loci. Cord blood iron levels were measured in 217 control infants.ResultsThree HFE variants showed correlations with birth weight with a gene–dosage relationship in males (gender effect). The association was stronger in homozygotes for TFRC S142G and when the mother was positive for any HFE variant (maternal effect). The genotypes expected to increase fetal iron levels correlated with birth weight in males and their association with ALL was stronger in females who, we postulate, could not offset iron excess by increasing their weight.ConclusionsCertain materno‐fetal genotype combinations that increase fetal iron exposure showed associations with higher birth weight in males and somewhat higher ALL risk in females. Gender‐specific use of iron during fetal growth may lead to this dichotomy in birth weight change. Only the materno‐fetal genotype combinations that increase iron levels most extremely correlated with birth weight and ALL risk in males. Pediatr Blood Cancer 2009; 53:1242–1248. © 2009 Wiley‐Liss, Inc.
Flow cytometric detection of Ewing sarcoma cells in peripheral blood and bone marrow
Authors: DuBois Steven G. , Epling C. Lorrie , Teague Juli , Matthay Katherine K. , Sinclair Elizabeth 
Published: August 2009

AbstractBackgroundA new method for detecting circulating Ewing sarcoma cells using flow cytometry is described. This strategy exploits the nearly universal expression of CD99 and the lack of expression of CD45 by Ewing sarcoma cells.ProcedureEwing sarcoma cell line A673, peripheral blood mononuclear cells (PBMCs), and bone marrow mononuclear cells (BMMCs) were stained for CD99 and CD45 in order to detect CD99+CD45− cells by flow cytometry. Known quantities of A673 Ewing sarcoma cells were spiked into control PBMCs to test the accuracy of this method. Control PBMCs were evaluated to assess the level of background staining.ResultsFlow cytometry was accurate at frequencies as low as one A673 cell per 500,000 PBMCs. The background rate of CD99+CD45− cell detection was low in PBMCs from nine healthy volunteers (median 0.0001% of total cells; range 0–0.00046%) and was further reduced by incorporating stains to exclude dead cells, progenitor cells, and monocytes. In one subject with newly diagnosed localized Ewing sarcoma, CD99+CD45− cells were detected in both blood (0.0021%) and bone marrow (0.048%).ConclusionsMulticolor flow cytometry for CD99+CD45− cells provides a new strategy for detecting circulating Ewing sarcoma cells. Clinical evaluation and validation of this method is ongoing. Pediatr Blood Cancer 2010; 54:13–18. © 2009 Wiley‐Liss, Inc.
Alginate‐nanofibers fabricated by an electrohydrodynamic process
Authors: Kim GeunHyung , Park Ko‐eun 
Published: August 2009

AbstractAlginate, a natural polymer, is potentially useful in biomedical applications, because it is very similar to macromolecular substances, unlike synthetic polymers that may cause problems due to toxicity and lack of recognition by cells. Alginate's processability characteristics, however, are a potential drawback to its use as a biomedical nanofiber scaffold. To improve electrospinnability, alginate has been processed with various synthetic polymers and surfactants. Although this has enhanced the processability of the polymer, a new approach is required to obtain a sufficient production rate over a short period of time. We used a multiple‐nozzle electrospinning system complemented with auxiliary cylindrical electrodes. The nanofibers of alginate/poly(ethylene oxide) supplemented with lecithin as a surfactant were electrospun using a multiple nozzle system. We measured the production rate and size uniformity of the spun fibers with and without auxiliary electrodes. We observed that a multiple nozzle system with auxiliary electrodes provided much better and more stable processability, as well as higher mass productivity of alginate nanofibers compared with a normal multiple nozzle system. The resulting nanofiber mat showed potential for use as a biomedical scaffold based on our tests with cell‐cultured human dermal fibroblasts. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers
Effect of rubber types on synthesis, morphology, and properties of ABS resins
Authors: Yu Zhisheng , Li Yang , Zhao Zhongfu , Wang Chaoxian , Yang Juan , Zhang Chunqing , Li Zhansheng , Wang Yurong 
Published: August 2009

AbstractA series of acrylonitrile–butadiene–styrene (ABS) copolymers were prepared using lithium‐catalyzed low‐cis rubber (PB700A), nickel‐catalyzed high‐cis rubber (BR9004), and their compounded rubber (PB700A/BR9004 = 50:50) as toughening agents through bulk polymerization. The effects of molecular structures of rubbers on the dissolving and grafting process of them were investigated. The structure and properties of ABS resins were characterized with FTIR, TEM, and performance measurements. It is shown that the characteristics of rubbers affect their dissolving state and grafting reaction and consequently influence the morphology and properties of ABS materials. BR9004 promotes the formation of irregular microsized rubber particles with special “salami”‐like structure and, therefore, presents better mechanical properties. PB700A has much higher 1,2‐isomers, which benefits its dispersion and grafting reaction; its toughening effect, however, is unsatisfactory and can be improved by the incorporation of BR9004. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers
Polyurethane dispersions derived from polycarbonatediols and m‐di(2‐isocyanatopropyl)benzene
Authors: Lee Da‐Kong , Yang Zong‐Da , Tsai Hong‐Bing , Tsai Ruey‐Shi 
Published: August 2009

AbstractAqueous polyurethane dispersions derived from various polycarbonatediols, m‐di(2‐isocyanatopropyl)benzene(TMXDI), and various carboxylic diols including dimethylol propionic acid (DMPA), dimethylol butyric acid (DMBA), and a carboxylic polycaprolactonediol (Placcel 205BA) were prepared by a method in which the dispersing procedure was modified to enhance the molecular weight. The NH2/NCO ratio during chain extension affected the molecular weight of the polyurethanes, significantly, and an optimum ratio of 0.67:1.0 was used. The molecular weight, particle size, tensile properties, and thermal properties of the polyurethane dispersions were investigated. The effect chemical structure of the polycarbonatediols on the properties shows no obvious trend, but the polyurethane dispersions derived from the carboxylic polycaprolactonediol exhibit smaller particle size and softer tensile properties when compared with those derived from DMPA and DMBA. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers
Study on the melt‐spinnability of poly(L‐lactic acid)
Authors: Zhang Huihui , Yang Gesheng , Wang Xiangbing , Shao Huili , Hu Xuechao 
Published: August 2009

AbstractIn this work, three kinds of different poly(L‐lactic acid) (PLLA) materials for melt‐spinning were investigated with respect to the molecular weight (MW) and molecular weight distribution (MWD), racemization, optical purity, thermal properties, and melt‐spinnability. It was found that the high MW was not the only factor to affect the melt spinnability of PLLA, the racemization and the amount of residual monomer would also affect the thermal properties and melt‐spinnability of PLLA. The results showed that it could be melt‐spun and hot‐drawn by using the general melt‐spinning device for PLLA pellet with good stereoregularity and comparatively high MW. For PLLA pellet with high MW and moderate stereoregularity, it must be treated at an appropriate temperature to increase the crystallinity before dry and extrusion, which could make the pellet be spun without agglomeration, whereas the draw ability of such as‐spun fiber was still poor. However, if the stereoregularity of PLLA pellet was poor, it could not be spun even it had very high MW. Only when MW, racemization, and the amount of residual monomer of the PLLA pellets all meet the requirements, PLLA fibers could be prepared by melt‐spinning. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers
Minimum “safe cycle time”: Selecting the frozen layer thickness
Authors: Chang Keh‐Chyou , Hioe Yunior , Villarreal Maria G. , Castro Jose M. 
Published: August 2009

AbstractPredicting the minimum safe cycle time in injection molding is complicated by the cyclic nature of the process. The mold thermal state changes with continuous molding until a quasi steady state is achieved. In the first part of these series, we presented and experimentally tested a simple approach to predict part and mold surface temperature during continuous molding. In this work, we evaluate the minimum frozen layer thickness required before the part can be demolded and how the growth of this frozen layer is affected as the mold thermal state changes with continuous molding cycles. Experiments are used to relate the minimum frozen layer thickness to dimensional stability. Based on these experiments, statistical tools are used to select an ejection criterion to obtain a minimum safe cooling time. We show that the ejection criteria should be adjusted depending on the precision required from the molded parts. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers
Nonisothermal crystallization kinetics of high‐density polyethylene/barium sulfate nanocomposites
Authors: Chen Xiaolei , Wang Lumin , Liu Yongli , Shi Jiangao , Shi Hang 
Published: August 2009

AbstractThe high‐density polyethylene (HDPE)/barium sulfate (BaSO4) nanocomposites had been successfully prepared by melt‐blending. Nonisothermal melt‐crystallization kinetics of neat HDPE and HDPE/BaSO4 nanocomposites was investigated with differential scanning calorimetry under different cooling rates. The nonisothermal crystallization behavior was analyzed by Ozawa, Avrami, and combined Ozawa–Avrami methods. It was found that the Ozawa method failed to describe the nonisothermal crystallization behavior of neat HDPE and HDPE/BaSO4 nanocomposites. The modified Avrami method by Jeziorny was only valid for describing the middle stage of crystallization but was not able to describe the later stage of neat HDPE and HDPE/BaSO4 nanocomposites crystallization. The value of Avrami exponent n for neat HDPE ranged from 3.3 to 5.7 and for HDPE/BaSO4 nanocomposites ranged from 1.8 to 2.5. It is postulated that the values of n close to 3 are caused by spherulitic crystal growth with heterogeneous nucleation, whereas simultaneous occurrence of spherulitic and lamellar crystal growth with heterogeneous nucleation account for lower values of n. The combined Ozawa–Avrami method by Mo and coworkers (Polym. Eng. Sci.,37(3), 568 (1997)) was able to satisfactorily describe the crystallization behavior of neat HDPE and HDPE/BaSO4 nanocomposites. In addition, the activation energy of nonisothermal crystallization was determined using the Kissinger (J. Res. Natl. Bur. Stand.,57(4), 217 (1956)) method, showing that the crystallization activation energy of HDPE/BaSO4 nanocomposites was lower than that of neat HDPE. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers
Birefringence in gas‐assisted tubular injection moldings: Simulation and experiment
Authors: Carrillo Antonio J. , Isayev A.I. 
Published: August 2009

AbstractThe influence of the processing variables on the birefringence and polymer/gas interface distribution is analyzed for polystyrene moldings obtained by gas‐assisted injection molding (GAIM) under various processing conditions. The processing variables studied were: melt and mold temperatures, shot size, gas pressure, injection speed, and gas‐delay time. Measurements and viscoelastic simulations of the radial distribution of birefringence components, Δn and nrr − nθθ, the variation of the average birefringence, 〈nzz − nθθ〉, along the molding and polymer/gas interface along the length of spiral‐shaped tubular moldings are presented. The polymer/gas interface distribution and flow stresses were simulated using a numerical scheme based on a hybrid finite element/finite difference/control volume method. The birefringence was calculated from the flow‐induced stresses using the stress‐optical rule. Simulations qualitatively agreed with measurements and correctly described theeffect of the processing variables on the birefringence andthe polymer/gas interface distribution in GAIM moldings. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers
New concept of reducing a birefringence of poly(ethylene naphthalate) by a novel alloy with fluorene‐based polyester
Authors: Kawasaki Shinichi , Kato Mariko , Kobori Kana , Sakamoto Hiroki , Kondo Yoshikazu , Takata Toshikazu 
Published: August 2009

AbstractThis study proposes the new concept of reducing the birefringence of poly(ethylene naphthalate) (PEN) by a novel alloy with fluorene‐based polyester (FBP) involving the “cardo” structure in it. The alloys composed of PEN and FBP were prepared by simple melt blending method (process A) and reactive melt blending (process B). The resulting alloys were characterized by DSC, XRD, DMA, tensile testing, and polarized light microscopy. All PEN‐FBP alloys showed transparency and a single glass transition temperature (Tg), indicating that PEN‐FBP alloys were completely compatible. It was also demonstrated that Tg for PEN was shifted to the high‐temperature side by alloying with FBP. A large amount of the orientation‐induced birefringence was induced in drawn PEN sheets; however, in the cases of PEN‐FBP alloys, it was drastically decreased because of alloying with FBP. We could reveal the new concept for “low‐orientation‐induced birefringence material.” POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers
Multiscale modeling of structural dynamics underlying force generation and product release in actomyosin complex
Authors: Zheng Wenjun 
Published: August 2009

AbstractTo decrypt the mechanistic basis of myosin motor function, it is essential to probe the conformational changes in actomyosin with high spatial and temporal resolutions. In a computational effort to meet this challenge, we have performed a multiscale modeling of the allosteric couplings and transition pathway of actomyosin complex by combining coarse‐grained modeling of the entire complex with all‐atom molecular dynamics simulations of the active site. Our modeling of allosteric couplings at the pre‐powerstroke state has pinpointed key actin‐activated couplings to distant myosin parts which are critical to force generation and the sequential release of phosphate and ADP. At the post‐powerstroke state, we have identified isoform‐dependent couplings which underlie the reciprocal coupling between actin binding and nucleotide binding in fast Myosin II, and load‐dependent ADP release in Myosin V. Our modeling of transition pathway during powerstroke has outlined a clear sequence of structural events triggered by actin binding, which lead to subsequent force generation, twisting of central β‐sheet, and the sequential release of phosphate and ADP. Finally we have performed atomistic simulations of active‐site dynamics based on an on‐path “transition‐state” myosin conformation, which has revealed significantly weakened coordination of phosphate by Switch II, and a disrupted key salt bridge between Switch I and II. Meanwhile, the coordination of MgADP by Switch I and P loop is less perturbed. As a result, the phosphate can be released prior to MgADP. This study has shed new lights on the controversy over the structural mechanism of actin‐activated phosphate release and force generation in myosin motor. Proteins 2010. © 2009 Wiley‐Liss, Inc.
Switching between low and high affinity for the Syk tandem SH2 domain by irradiation of azobenzene containing ITAM peptidomimetics
Authors: Kuil Joeri , van Wandelen Loek T.M. , de Mol Nico J. , Liskamp Rob M.J. 
Published: August 2009

AbstractSpleen tyrosine kinase (Syk) plays an essential role in IgE receptor signaling (FcεRI), which leads to mast cell degranulation. Divalent binding of the tandem SH2 domain (tSH2) of Syk to the intracellular ITAM motif of FcεRI activates the kinase domain of Syk, and thereby initiates cell degranulation. The inter SH2 domain distance in Syk tSH2 might be important for Syk kinase activation. In this study, photoswitchable ITAM peptidomimetics containing an azobenzene moiety were synthesized. Irradiation of these constructs changes the distance between the two SH2 binding epitopes and therefore, they may be used as photoswitches. The affinity of the cis‐ and trans‐isomer for tSH2 was assayed with SPR. The ITAM peptidomimetic with the smallest linker displayed the largest difference in affinity between the two isomers (at least 100‐fold), and the affinity of the cis‐isomer was comparable to monovalent binding. The ITAM mimics with larger photoswitchable linkers displayed modest differences. These results indicate that Syk tSH2 is able to adapt the inter SH2 domain distance to ligands larger than native ITAM, but not to smaller ones. Copyright © 2009 European Peptide Society and John Wiley & Sons, Ltd.
Whittaker–Hill equation, Ince polynomials, and molecular torsional modes
Authors: Roncaratti Luiz F. , Aquilanti Vincenzo 
Published: August 2009

AbstractWe present an analysis of the Whittaker–Hill equation in view of its usefulness in quantum mechanics when periodic potentials are involved. The transformation due to Ince leads to polynomial solutions which have not attracted much attention so far in the applications. With respect to Mathieu equation, here we have an additional parameter, which permits to describe a variety of phenomena, including the treatment of the torsional motion of flexible molecules. Examples are discussed, with particular attention payed to the case of H2O2 and similar molecules. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010
Theoretical study of photochromic compounds, part 2: Thermal mechanism for byproduct formation and fatigue resistance of diarylethenes used as data storage materials
Authors: Patel Pansy D. , Mikhailov Ivan A. , Belfield Kevin D. , Masunov Artëm E. 
Published: August 2009

AbstractCertain organic compounds possess the ability to change color under the influence of light, called photochromism. This change is due to ultrafast chemical transition from open to closed ring isomers (photocyclization), which can be used for optical data storage and photoswitching applications. These applications require minimization of the irreversible photodegradation of the material, called photofatigue. This property is related to the chemical rate of byproduct formation. We use density functional theory methods to predict the mechanism and activation barriers to the byproduct formation for 1,2‐bis(2‐methyl‐5‐phenyl‐3‐thienyl)perfluorocyclopentene in order to estimate its fatigue resistance. We also explain higher fatigue resistance for its methylated derivative. The methods used in this study may become a part of rational design strategy for the new photochromic materials. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Extended Hartree–Fock theory of chemical reactions. IX. Diradical and perepoxide mechanisms for oxygenations of ethylene with molecular oxygen and iron‐oxo species are revisited
Authors: Yamaguchi Kizashi , Yamanaka Syusuke , Shimada Jiro , Isobe Hiroshi , Saito Toru , Shoji Mitsuo , Kitagawa Yasutaka , Okumura Mitsutaka 
Published: August 2009

AbstractSymmetry and broken symmetry (BS) in molecular orbital description of transition structures and intermediates in oxygenation reactions have been revisited to elucidate states correlation diagrams and mechanisms for addition reactions of molecular oxygen and metal‐oxo MO (M = Mn(II) and Fe(II)) species to CC double bonds. Relative stabilities between diradical (DR) and perepoxide (PE) intermediates were thoroughly investigated by several BS hybrid DFT (HDFT) methods and BS CCSD(T) method with and without spin projection. It has been found that recovery of spin symmetry, namely eliminating spin contamination error from the BS solutions, is crucial for the elucidation of reasonable state correlation diagrams and energy differences of the key structures in the oxygenation reactions because the singlet‐triplet energy gap for molecular oxygen is large (22 kcal/mol). The BS HDFT followed by spin correction reproduced activation barriers for transition structures along both PE and DR reaction pathways by the use of the CASPT2 method. Basis set dependence on the relative stability between PE and DR intermediates were also examined thoroughly. Solvation effect for DR and PE intermediates was further examined with self‐consistent reaction field (SCRF) and SCIPCM methods. Both BS HDFT and CASPT2 have concluded that the DR mechanism is favorable for the addition reaction of singlet oxygen to ethylene, supporting our previous conclusions. The BS HDFT with spin correction was concluded to be useful enough for theoretical investigations of mechanisms of oxygenation reactions. Implications of the computational results were discussed in relation to the theoretical framework (four configuration model) for elucidation of possible mechanisms of epoxidation reactions with Fe(IV)O cores in metalloenzymes on the basis of isolobal analogies among O, OO, and Fe(IV)O. Correspondence between magnetic coupling mode and radical pathway in oxygenations with these species was clarified based on the BS MO interaction diagrams, leading to local singlet and triplet diradical mechanisms for epoxidations. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Approximately spin‐projected Hessian for broken symmetry method and stretching frequencies of F2 and singlet O2
Authors: Kitagawa Yasutaka , Saito Toru , Nakanishi Yasuyuki , Kataoka Yusuke , Shoji Mitsuo , Koizumi Kenichi , Kawakami Takashi , Okumura Mitsutaka , Yamaguchi Kizashi 
Published: August 2009

AbstractAn approximate spin projection (AP) method is applied to a second derivative of energy (Hessian) of the broken‐symmetry (BS) method in order to eliminate a spin contamination error. Stretching frequencies of F2 (X1 ∑) and singlet molecular oxygen (a1Δg) are calculated by using the spin‐projected Hessian (AP Hessian). In case of F2 molecule, a potential curve of an unrestricted Hartree‐Fock (UHF) method does not have an energy minimum but the stretching frequency can be calculated by the AP UHF method. The difference in the calculated stretching frequencies between a restricted HF (RHF) and the AP UHF methods is 650–700 cm−1, and indicates that a static correlation correction is a crucial to consider the frequency. On the other hand, we cannot find a significant difference in calculated frequencies of RHF and AP‐BS HF in case of 1O2 molecule within the HF method. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009