bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inverse Suspension Polymerization of Partially Neutralized and Lightly Cross‐Linked Acrylic Acid: Effect of Reaction Parameters
Authors: Choudhary Manjeet S. 
Published: March 2009

AbstractAn inverse suspension polymerization was carried out in laboratory in one Liter Buchi glass reactor to produce superabsorbent polymers (SAPs) based on acrylic monomers for hygiene applications. Strongly water absorbing polymers, based on acrylic acid, sodium acrylate were prepared by copolymerization using potassium per sulfate as initiator and N‐N′ methylene‐bisacrylamide (MBA) as crosslinking agent.The effect of varying monomer, crosslinker, initiator, dispersant concentration, time of reaction and degree of neutralization, on absorption capacities was investigated. In the present studies, the continuous hydrocarbon phase was taken as 50:50 mixture of n‐heptane and cyclohexane (aliphatic‐alicyclic) because the availability of crosslinker in the aqueous phase is controlled by the partition coefficient of the crosslinker between the aqueous phase and the continuous hydrocarbon phase. The SAPs were evaluated for their free absorption capacities in distilled water, saline (0.9% NaCl), and also absorption under load (AUL). The experimental results show that these SAPs have good absorbency both in water and NaCl solutions. It was observed that SAP synthesized from acrylic acid with about 70% degree of neutralization, containing 1% cross‐linker, and 0.5–1.0% initiator concentration with 10% dispersant exhibited absorption capacities in water, saline and AUL as 220 g/g, 70 g/g and 27 g/g respectively.
Development of Oligomeric Phthalonitrile Resins for Advanced Composite Applications
Authors: Selvakumar Palaniappan , Sarojadevi Muthusamy 
Published: March 2009

AbstractPhthalonitrile endcapped oligomers containing aromatic ether and imide linkages have been synthesized and characterized. The phthalonitrile terminated oligomers were prepared in two step (one spot) method by the reaction of an excess amount of pyromellitc dianhydride (PMDA) with aromatic diamines, in a N,N‐dimethylacetamide (DMAc)/toluene solvent mixture to form anhydride terminated oligomeric intermediate that was terminated by the reaction with 4‐(aminophenoxy) phthaloitrile. The average molecular weights of the prepared oligomers were determined by GPC analysis. The oligomeric phthalonitrile monomers have been converted to network polymers using 4,4'‐diaminodiphenyl sulfone (DDS) (5.0 wt %) curing additive at elevated temperatures. Differential scanning calorimetric (DSC) analysis was used to follow the polymerization as the oligomeric phthalonitrile/diamine mixtures and prepolymers. An isothermal rheometric analysis was conducted to determine the complex viscosity of the prepolymers during polymerization reaction. Viscosity increases as a function of time due to crosslinking, which depends upon the concentration and reactivity of the curing agent. The TGA analysis of cured resins showed superior thermal and thermo‐oxidative stability. The temperature of 10% weight loss from TGA are in the range of 498‐511 °C in N2 and 448–461 °C in air atmosphere. Char yield at 800 °C is 41.7–50.2% in air and 70.6–83.1% in N2.
Photocurable Fluorinated Methacrylates: Synthesis and Polymerization
Authors: Shim Sang‐Yeon , Kim Eei Seok 
Published: March 2009

AbstractA series of hydroxy fluoroalkyl methacrylates were synthesized in 50% yields by the esterification reaction of the methacryloyl chloride with fluoroalkyl diol. These fluorinated methacrylates undergo rapid photopolymerization using Igacure651 as a photoinitiator. Hydrogels were prepared from various molar ratios of 2‐hydroxyethylmethacrylate (HEMA), ethylene glycol dimethacrylate and fluorine containing monomers with a photoinitiator. Analyzing the water contents and contact angles of the hydrogels, we found that the content of fluorinate monomers increased, water contents decreased and contact angles increased.
Recent Advances and Applications of “Successive Self‐Nucleation and Annealing” (SSA) High Speed Thermal Fractionation
Authors: Müller Alejandro J. , Lorenzo Arnaldo T. , Arnal María L. 
Published: March 2009

AbstractThe Successive Self‐nucleation and Annealing (SSA) thermal fractionation technique is briefly reviewed to highlight recent advances such as the use of high speed DSC concepts to perform faster fractionation. Additionally, recent applications of SSA to characterize confined semi‐crystalline model polyethylenes in block copolymer nanophases and in situ prepared nanocomposites with carbon nanotubes are also reviewed. A novel result presented here deals with the use of a macromolecular plasticizer to improve the quality of SSA thermal fractionation.
Complete assignments of 1H and 13C NMR data for two new sesquiterpenes from Cyperus rotundus L.
Authors: Xu Yan , Zhang Hong‐Wu , Wan Xiao‐Chun , Zou Zhong‐Mei 
Published: March 2009

AbstractTwo new sesquiterpenes, epi‐guaidiol A (1) and sugebiol (3), together with four known sesquiterpenes, guaidiol A(2), sugetriol triacetate (4), cyperenoic acid (5), and cyperotundone (6) were isolated from the rhizomes of Cyperus rotundus L. Their structures were identified by MS and NMR experiments, and the complete assignments of 1H and 13C NMR data for two new sesquiterpenes were obtained by the aid of two‐dimensional (2D) NMR techniques, including HSQC, HMBC, 1H‐1HCOSY and nuclear overhauser enhancement spectroscopy(NOESY). Copyright © 2009 John Wiley & Sons, Ltd.
Improved pulse sequences for measurement of small long‐range couplings between heteronuclei (29Si13C) at natural abundance
Authors: Blechta Vratislav , Schraml Jan 
Published: March 2009

AbstractThe gradient pulse sequences for measurement of small long‐range couplings between heteronuclei (29Si13C) in natural abundance reported to date (INEPT‐(Si,C)gCOSY and INEPT‐(Si,C,Si)HMQC) suffer from significant signal loss when these nuclei (29Si, 13C) are coupled through one‐bond couplings to protons. This negative effect can be completely eliminated by using non‐gradient versions (INEPT‐(Si,C)COSY) or by switching proton decoupling off during gradient pulses (modified INEPT‐(Si,C,Si)gHMQC pulse sequence). The beneficial effects of these two approaches on the quality of the spectra are demonstrated here. Copyright © 2009 John Wiley & Sons, Ltd.
Immunocontraceptive potential of the Ig‐like domain of Izumo
Authors: Wang Min , Lv Zhengmei , Shi Jianli , Hu Yanqin , Xu Chen 
Published: March 2009

AbstractTo investigate whether the Ig‐like domain of sperm protein Izumo or the other part of the protein could be used as an immunocontraceptive antigen, three partially overlapping cDNA fragments (PA, PB, and PC), together covering entire mouse Izumo, were cloned, expressed, and purified. PB contains the whole Ig‐like domain of mouse Izumo. The anti‐PB antibody significantly inhibited the fusion of sperm with zona‐free mouse eggs with no effect on sperm motility, while anti‐PA and anti‐PC antibodies virtually had no effect on sperm–egg fusion at the same concentration. Furthermore, in the presence of anti‐PB antibody, the anti‐sperm reactivity could be competitively inhibited by recombinant PB protein. The PB‐specific antibody staining was restricted to the acrosome region in acrosome‐reacted mouse spermatozoa by indirect immunofluorescence. Active immunization with the PB antigen sharply raised the antibody titers in mouse that were enough to cause a significant reduction in fertility compared to the PA and PC immunized groups. In conclusion, our data indicate that the Ig‐like domain of Izumo plays an important role in the fertilization process, as verified by the dose‐dependent reduction in fertilization rates in mouse IVF trials and mouse mating assay. These results indicate that the Ig‐like domain of Izumo might be a new candidate for the development of a contraceptive vaccine. Mol. Reprod. Dev. 76: 794–801, 2009. © 2009 Wiley‐Liss, Inc.
Effects of culture medium and protein supplementation on mRNA expression of in vitro produced bovine embryos
Authors: Purpera M.N. , Giraldo A.M. , Ballard C.B. , Hylan D. , Godke R.A. , Bondioli K.R. 
Published: March 2009

AbstractNumerous studies have reported aberrant gene expression levels attributed to suboptimal in vitro culture conditions. This study investigated the effects of different culture systems and protein sources on the developmental competence of in vitro production (IVP) embryos measured by cleavage and blastocyst rates, cell number, and relative abundance of POU5F1 (OCT4), nanog, GJA1 (connexin 43), and SLC2A1 (GLUT1) transcripts when compared to in vivo embryos. Experiment 1 compared IVP embryos cultured in either synthetic oviductal fluid (SOFaa) or potassium simplex optimized medium supplemented with amino acids (KSOMaa). Experiment 2 compared the same two culture systems with and without the addition of calf serum (CS). Results from both experiments indicated that despite similar developmental rates, significant differences were observed at the mRNA level. In Experiment 1, OCT4 was the only transcript to have a mean abundance level significantly higher in KSOMaa blastocysts when compared with both SOFaa and in vivo embryos. The same pattern of upregulation of OCT4 mRNA was noted in Experiment 2. There were no significant alterations of the ICM specific transcript nanog in either experiment. In contrast to reports by others, connexin 43 mRNA was not expressed at detectable levels in in vivo embryos analyzed in our studies. Blastocysts cultured in SOFaa with CS or KSOMaa had a significant upregulation of GLUT1 mRNA when compared with other treatments and in vivo embryos. Until differences between IVP and in vivo embryos are minimized, aberrations in IVP will continue to arise. Mol. Reprod. Dev. 76: 783–793, 2009. © 2009 Wiley‐Liss, Inc.
Guanidinoacetate methyltransferase (GAMT) deficiency diagnosed by proton NMR spectroscopy of body fluids
Authors: Engelke Udo F. H. , Tassini Maria , Hayek Joseph , de Vries Maaike , Bilos Appie , Vivi Antonio , Valensin Gianni , Buoni Sabrina , Zannolli Raffaella , Brussel Wim , Kremer Berry , Salomons Gajja S. , Veendrick‐Meekes Monique J. B. M. , Kluijtmans Leo A. J. , Morava Éva , Wevers Ron A. 
Published: March 2009

AbstractIn patients with guanidinoacetate methyltransferase (GAMT) deficiency several parameters may point towards the diagnosis of GAMT deficiency. These include the low levels of creatine and creatinine in urine, the high concentration of guanidinoacetic acid (GAA) in urine and the low levels of creatine and creatinine in the cerebrospinal fluid (CSF). In this study, body fluids from 10 GAMT deficient patients were analysed using 1H NMR spectroscopy. The urine 1D 1H NMR spectra of all the patients showed a doublet resonance at 3.98 ppm (pH 2.50) derived from GAA present in high concentration. For this compound, a good recovery and good correlation was found between an LC‐MS/MS method and 1H NMR spectroscopy. In CSF NMR spectra of these patients, the singlet resonances of creatine and creatinine (3.05 and 3.13 ppm, respectively) were absent (normally always present in 1H NMR spectra of CSF). Due to overlap by other resonances, the doublet of GAA could not be observed. Our data demonstrate that 1H NMR spectroscopy of urine and CSF can be used to diagnose patients with GAMT deficiency. Copyright © 2009 John Wiley & Sons, Ltd.
Thermal history dependence of polymorphic transformation of polyamide 6/silicate nanocomposites
Authors: Zhao Xiong‐yan 
Published: March 2009

AbstractBACKGROUND: Although much research has been devoted to nanocomposites of polyamide 6 (PA6) with inorganic nanoparticles, most research has mainly focused on the effects of clay and annealing temperature on the crystallization behavior of the PA6 matrix, but the effect of annealing on the thermal behavior of PA6/clay nanocomposites remains an interesting subject which requires further investigation. This paper focuses on the effects of thermal history on the polymorphic transformation of PA6 and PA6/layered silicate nanocomposites (PA6LSN).RESULTS: It was found that PA6 and PA6LSN exhibit a similar polymorphic behavior when they were annealed at 190 °C. As the annealing temperature was elevated to 230 and 250 °C, significant differences in polymorphic transformation and thermal behavior between PA6 and PA6LSN could be observed. For example, the γ phase became the dominant crystalline phase for PA6LSN samples while the α crystal was still the predominant phase in neat PA6. Furthermore, a higher temperature endothermic peak observed at around 236 °C in all PA6LSN modulated differential scanning calorimetry scans was also found to be strongly dependent on the cooling rate and annealing temperature.CONCLUSION: The thermal history has a strong influence on the polymorphic transformation of PA6 and PA6LSN. For the first time, the effect of thermal history on the high‐temperature endothermic peak of PA6LSN was investigated and it was observed that this peak is also strongly dependent on the thermal history. Copyright © 2009 Society of Chemical Industry
Measurement and simulation of low‐density polyethylene extrudate swell through a circular die
Authors: Mu Yue , Zhao Guoqun , Li Huiping , Liu Jie , Xu Xingming , Mu Wenbo , Chen Anbiao 
Published: March 2009

AbstractBACKGROUND: Extrudate swell is a common phenomenon in polymer processing. The investigation of its mechanism is of both scientific and industrial interest.RESULTS: The rheological parameters of a material described by the viscoelastic PTT (Phan‐Thien–Tanner) constitutive model are obtained by fitting the distributions of material functions detected with a strain‐controlled rheometer. The swelling ratios of low‐density polyethylene (LDPE) under different volume flow rates are indirectly obtained using a photographic technique. A mathematical model of extrudate swell is established and its finite element model is derived. A penalty method is employed to solve the extrudate swell problem with a decoupled algorithm. Computation stability is improved by using the discrete elastic‐viscous split stress algorithm incorporating the inconsistent streamline‐upwind scheme.CONCLUSION: The swell phenomenon of LDPE through a circular die is investigated using both experimental measurement and numerical simulation. The swelling ratios obtained from the simulation are compared with those measured: they agree well with each other. The essential flow characteristics of polymer melts are predicted and the mechanism of the swell phenomenon is further discussed. Copyright © 2009 Society of Chemical Industry
n‐Type multicrystalline silicon wafers prepared from plasma torch refined upgraded metallurgical feedstock
Authors: Martinuzzi S. , Périchaud I. , Trassy C. , Degoulange J. 
Published: March 2009

Abstractn‐Type silicon wafers present some definite advantages for the photovoltaic industry, mainly due to the low capture cross sections of minority carriers for most metallic impurities. This peculiarity is beneficial for multicrystalline silicon (mc‐Si) wafers in which the interaction between crystallographic defects and impurities is the main source of recombination centres. Most importantly, this peculiarity could be of a great interest when mc‐Si ingots are produced directly from upgraded and purified metallurgical silicon feedstock. It is of a paramount importance to verify if the advantages of conventional n‐type silicon also characterizes n‐type wafers provided by a direct metallurgical route. It is found, in raw wafers, that minority carrier diffusion lengths are three times higher in n‐type than in p‐type wafers, when the wafers are cut from the same ingot, where the bottom is p‐type and the top is n‐type, due to the difference in the segregation coefficients of doping elements (boron and phosphorus). After different processing steps and gettering treatments the minority carrier diffusion lengths are always neatly larger in n‐type than in p‐type wafers The results confirm the interest for n‐type silicon. Copyright © 2009 John Wiley & Sons, Ltd.
Sunrise to sunset optimization of thin film antireflective coatings for encapsulated, planar silicon solar cells
Authors: Boden S. A. , Bagnall D. M. 
Published: March 2009

AbstractWe present an approach for the optimization of thin film antireflective coatings for encapsulated planar silicon solar cells in which the variations in the incident spectra and angle of incidence (AOI) over a typical day are fully considered. Both the angular and wavelength dependences of the reflectance from the surface, absorptance within the coating, and transmittance into the device are calculated for both single‐ and double‐layer antireflection coatings with and without thin silicon oxide passivation layers. These data are then combined with spectral data as a function of time of day and internal quantum efficiency to estimate the average short‐circuit current produced by a fixed solar cell during a day. This is then used as a figure of merit for the optimization of antireflective layer thicknesses for modules placed horizontally at the equator and on a roof in the UK. Our results indicate that only modest gains in average short‐circuit current could be obtained by optimizing structures for sunrise to sunset irradiance rather than AM1·5 at normal incidence, and fabrication tolerances and uniformities are likely to be more significant. However, we believe that this overall approach to optimization will be of increasing significance for new, potentially asymmetric, antireflection schemes such as those based on subwavelength texturing or other photonic or plasmonic technologies currently under development especially when considered in combination with modules fixed at locations and directions that result in asymmetric spectral conditions. Copyright © 2009 John Wiley & Sons, Ltd.
A hierarchical MS2/MS3 database search algorithm for automated analysis of phosphopeptide tandem mass spectra
Authors: Xu Hua , Wang Liwen , Sallans Larry , Freitas Michael A. 
Published: March 2009

AbstractA novel hierarchical MS2/MS3 database search algorithm has been developed to analyze MS2/MS3 phosphopeptides proteomic data. The algorithm is incorporated in an automated database search program, MassMatrix. The algorithm matches experimental MS2 spectra against a supplied protein database to determine candidate peptide matches. It then matches the corresponding experimental MS3 spectra against those candidate peptide matches. The MS2 and MS3 spectra are used in concert to arrive at peptide matches with overall higher confidence rather than combining MS2 and MS3 data searched separately. Receiver operating characteristic analysis showed that hierarchical MS2/MS3 database searches with MassMatrix had better sensitivity and specificity than the two‐stage MS2/MS3 database searches obtained with MassMatrix, MASCOT, and X!Tandem. A greater number of true peptide matches at a given false rate were identified by use of this new algorithm for data collected on both LCQ and LTQ‐FTICR mass spectrometers. The additional MS3 spectral data also improved the overall reliability and the number of true positives (TPs) due to the fact that the TPs of the MS2/MS3 search results had higher scores than those of the MS2.
A combined experimental and theoretical study of the pH‐dependent binding mode of NAD+ by water‐soluble molecular clips
Authors: Polkowska Jolanta , Bastkowski Frank , Schrader Thomas , Klärner Frank‐Gerrit , Zienau Jan , Koziol Felix , Ochsenfeld Christian 
Published: March 2009

AbstractThe highly selective recognition process of NAD+ and NADH (as important cofactors of many redox enzymes) by molecular clips in aqueous solution is studied systematically by a combined experimental and quantum‐chemical approach. The strongly pH‐dependent complexation‐induced 1H NMR shifts of the guest molecule indicate that in buffered aqueous solution at pH = 7.2 the nicotinamide ring, the active site of NAD+, is preferentially bound inside the cavity of the molecular clip, whereas in pure water under slightly acidic conditions both units (the nicotinamide ring as well as the adenine moiety) are located outside the cavity. The latter finding is explained by a competing self‐aggregation of NAD+ which prohibits the recognition process. In addition, the investigation of the NAD+ fragments NMNA, NMN, and AMP as well as the comparison of measured and computed chemical shieldings provides information on possible binding modes. Under equal conditions the binding of NADH to the molecular clip is significantly weaker than that of NAD+, so that the oxidation states (NAD+/NADH) can be distinguished by the molecular clips. The nucleotides NMN and AMP are bound less strongly by the molecular clips than NAD+. The weaker binding indicates that multiple aromatic π−π and cation−π host–guest interactions only possible in NAD+ have a synergetic effect on the complex stability. In addition to the inhibition of the cofactor NAD+, a further implication is the development of sensors since a quenching of fluorescence is observed for specific molecular clips by the addition of NAD+. Copyright © 2009 John Wiley & Sons, Ltd.
Bromoxynil degradation in a Mississippi silt loam soil
Authors: Zablotowicz Robert M , Krutz L Jason , Accinelli Cesare , Reddy Krishna N 
Published: March 2009

AbstractBACKGROUND: The objectives of these laboratory experiments were: (1) to assess bromoxynil sorption, mineralization, bound residue formation and extractable residue persistence in a Dundee silt loam collected from 0–2 cm and 2–10 cm depths under continuous conventional tillage and no‐tillage; (2) to assess the effects of autoclaving on bromoxynil mineralization and bound residue formation; (3) to determine the partitioning of non‐extractable residues; and (4) to ascertain the effects of bromoxynil concentration on extractable and bound residues and metabolite formation.RESULTS: Bromoxynil Kd values ranged from 0.7 to 1.4 L kg−1 and were positively correlated with soil organic carbon. Cumulative mineralization (38.5% ± 1.5), bound residue formation (46.5% ± 0.5) and persistence of extractable residues (T1/2 < 1 day) in non‐autoclaved soils were independent of tillage and depth. Autoclaving decreased mineralization and bound residue formation 257‐fold and 6.0‐fold respectively. Bromoxynil persistence in soil was rate independent (T1/2 < 1 day), and the majority of non‐extractable residues (87%) were associated with the humic acid fraction of soil organic matter.CONCLUSIONS: Irrespective of tillage or depth, bromoxynil half‐life in native soil is less than 1 day owing to rapid incorporation of the herbicide into non‐extractable residues. Bound residue formation is governed principally by biochemical metabolite formation and primarily associated with soil humic acids that are moderately bioavailable for mineralization. These data indicate that the risk of off‐site transport of bromoxynil residues is low owing to rapid incorporation into non‐extractable residues. Published 2009 by John Wiley & Sons, Ltd
A sterile‐female technique proposed for control of Striga hermonthica and other intractable weeds: advantages, shortcomings and risk management
Authors: Rector Brian G 
Published: March 2009

AbstractWeeds have posed intractable challenges to farmers since the dawn of agriculture. This article describes in detail a proposed control strategy based on the introduction of genes conferring female sterility into the genome of an intractable target weed. Spread of these genes through target populations via pollen would be facilitated by their incorporation within active transposable elements. Advantages (e.g. self‐dissemination, self‐proliferation, target specificity) and shortcomings (e.g. high cost, long project incubation period, limited range of possible targets) of this strategy are discussed in depth, as are assessment and management of its attendant biological and ecological risks, such as the risk of introduced genes spreading to non‐target species. The parasitic weed Striga hermonthica (Del.) Benth. is examined as a potential target. Published 2009 by John Wiley & Sons, Ltd