bluuebunny/crossref_metadata_2025_split huggingface dataset:
Extending slice coverage for breathhold fat‐suppressed T2‐weighted fast spin‐echo of the liver at 3.0T: Application of variable‐rate selective‐excitation (VERSE) RF pulses
Authors: van den Bos Indra C. , Hussain Shahid M. , Krestin Gabriel P. , Wielopolski Piotr A. 
Published: December 2007

AbstractPurposeTo determine the benefits of variable‐rate selective‐excitation (VERSE) radio frequency (RF) pulses for increased slice coverage in breathhold (BH) fat‐suppressed T2‐weighted fast spin‐echo (FS‐T2W‐FSE) liver imaging at 3.0T.Materials and MethodsA total of 12 healthy volunteers were imaged on 3.0T, using FS‐T2W‐FSE. Slice coverage and specific absorption rate (SAR) levels were monitored for VERSE‐RF and standard‐RF (sRF), respectively. BH time was 25 seconds; slice thickness 3.5 mm. Maximum coverage was recorded for interactive variation of repetition time (TR), bandwidth (BW), and echo‐train length (ETL). Image quality was assessed qualitatively and quantitatively.ResultsTotal slice coverage was always higher using VERSE‐RF, but varied depending on the selected parameters. For BW ≥ 62.5 kHz, slice coverage using VERSE increased between 38% (TR = 8200 msec) and 58% (TR = 2500 msec). Maximum coverage was obtained for TR = 5000 msec, ETL = 12, and BW ≥ 62.5 kHz; with a mean of 31.8 slices for VERSE‐RF and 22.5 slices for sRF, respectively (P < 0.005, 41% increased coverage). SAR was lower for VERSE‐RF using BW < 41.67 kHz (P < 0.05), and equal to sRF for higher BW. Image quality was best for TR ≤ 5000 msec (P < 0.05). FS was more homogeneous for lower ETL (P < 0.05). Blood suppression was best for TR ≤ 5000 msec (P < 0.05).ConclusionVERSE‐RF pulses can be applied for thin‐slice BH FS‐T2W liver imaging at 3.0T, with significantly improved slice coverage. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
How does coaching interviewees affect the validity of a structured interview?
Authors: Maurer Todd J. , Solamon Jerry M. , Lippstreu Michael 
Published: December 2007

AbstractCoaching interviewees to perform in employment interviews can influence the interview scores. We describe different types of coaching, emphasizing interventions designed to focus interviewees on core, interview‐relevant content and to help them convey the content accurately (as opposed to interventions designed to teach interviewees to manipulate their scores using peripheral means). We then study the effects of the former type of intervention in relation to the criterion‐related validity of a structured employment interview. In a combined sample of 146 public safety job incumbents, a predictive validation study was conducted using scores from a situational panel interview. Predictive validity and reliability was observed to be higher in a sample of coached interviewees compared to a sample of uncoached interviewees. Implications for future research and practice in organizational behavior are discussed. Copyright © 2007 John Wiley & Sons, Ltd.
Intermolecular H‐bond in propan‐2‐ol and its solutions with acetonitrile
Authors: Tukhvatullin F. H. , Jumabaev A. , Hushvaktov H. , Absanov A. , Shaymanov A. 
Published: December 2007

AbstractFormation of propan‐2‐ol–acetonitrile dimers is manifested in the Raman spectra as an appearance of a band of aggregates in the high‐wavenumber side of the CN vibrational band of liquid acetonitrile (∼2 cm−1). The intensity of the band of aggregates changes with a change in the concentration of the mixture (1–0.05 mole fraction).For propan‐2‐ol we carried out nonempirical calculations of a structure of isolated dimer aggregates. The formation of an intramolecular H‐bond between the H and the O atom of the
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group of length 2.045 Å is possible in the monomer molecule. The CH3 groups of alcohol are not equivalent. In the dimer formation, intramolecular H‐bond in the \newbox\osprulebox
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group is preserved. An intermolecular H‐bond of length 2.045 Å and energy 15 kJ/mole is formed between the H atom of one molecule and the O atom of another molecule of the OH. The length and energy of the H‐bond for the propan‐2‐ol–acetonitrile dimer formations calculate to 2.27 Å and 12.9 kJ/mole, respectively. The H‐bond is formed by σ‐electrons of nitrogen. The experimental data and the results of calculations are in good agreement. Copyright © 2007 John Wiley & Sons, Ltd.
Concentration dependent Raman and IR study on salicylaldehyde in binary mixtures
Authors: Fathima A. Anis , Umadevi M. , Ramachandran M. S. , Ramakrishnan V. 
Published: December 2007

AbstractA vibrational spectroscopic study of binary mixtures of salicylaldehyde (SA) in three different solvents (polar and nonpolar) is presented. The vibrational modes ν(CO), hydroxyl stretching mode (COH) and aldehydic (CH) stretching vibration were analyzed. Changes in wavenumber position and full width half maximum have been explained for neat as well as binary mixtures with different volume fractions of the reference system, SA, in terms of inter‐ and intramolecular hydrogen bonding. The IR spectra of these mixtures have also been taken and compared with the Raman data. The spectral changes have been well explained using the concentration fluctuation model and solute–solvent interaction. Copyright © 2007 John Wiley & Sons, Ltd.
Influence of the Thiol Structure on the Kinetics of Thiol‐ene Photopolymerization with Time‐Resolved Infrared Spectroscopy
Authors: Wutticharoenwong Kosin , Soucek Mark D. 
Published: December 2007

AbstractPhotopolymerization kinetics of difunctional thiols with alkenes were studied. Two of the thiols, trans‐1,4‐bis(mercaptomethyl)cyclohexane (CHDMT) and 1,4‐bis(mercaptomethyl)benzene (BDMT) were synthesized. The CHDMT was synthesized via a two step process using potassium thioacetate and hydrochloric acid as reagents. The BDMT was synthesized by a one step process using 1,4‐benzenedimethanebromine with thiourea and potassium hydroxide as reagents. Three types of alkenes (divinyl ether, diallyl ether, and dimethacrylate) were reacted with CHDMT, BDMT or 1,8‐octanedithiol (ODT). The photopolymerization was investigated with and without a photoinitiator. The kinetics of the thiol‐ene photopolymerization was investigated by time‐resolved infrared spectroscopy. It was proposed that the steric hindrance of the cyclohexane (CHDMT) resulted in a lower rate of photopolymerization compared to BDMT and ODT. The vinyl ether (alkene) exhibited the highest activity compared to allyl ether and acrylate which was attributed to a high electron density of the alkene. Incorporation of photoinitiator increased the reaction rate and final conversion of the system, particularly in the ODT system.magnified image
Nano‐Explosions of Nanoparticles for Sudden Release of Substances by Embedded Azo‐Components as Obtained via the Miniemulsion Process
Authors: Volz Marissa , Walther Paul , Ziener Ulrich , Landfester Katharina 
Published: December 2007

AbstractThe solid and thermally instable azoinitiators V‐65 and VR‐110 were embedded within a polymer particle by using the miniemulsion process and afterwards quickly decomposed by thermal treatment below the glass temperature of the polymer. The resulting nitrogen gas overpressure inside the particles leads to a disruption of the polymer particle and a possible sudden release of encapsulated substances. It is shown, by electron microscopic measurements, that the number of burst particles correlates with the applied temperatures as well as the heating time. The surface deformation could be verified by scanning electron microscope analyses.magnified image
Dart Impact Testing of Polyethylene Film: Mechanical Interpretation and Model
Authors: Kissin Yury V. 
Published: December 2007

AbstractA physical model of dart impact tests of film manufactured from semi‐crystalline polyethylene resins is developed. The models treat the dart impact tests as a special case of the standard high‐speed stress/strain measurement performed on a polymer sample with a linearly changing cross section. They describe the dart impact strength as a complex function of the parameters that characterize the stress‐strain curve of the resin: stresses and strains at the yield, necking and breaking points. The models correctly predict the range of the dart impact strength (ASTM D1709, ISO 7765) and are suitable for semi‐quantitative characterization and ranking of linear low density polyethylene resins for film applications.magnified image
Imaging cadavers: Cold FLAIR and noninvasive brain thermometry using CSF diffusion
Authors: Tofts Paul S. , Jackson Jonathan S. , Tozer Daniel J. , Cercignani Mara , Keir Geoffrey , MacManus David G. , Ridgway Gerard R. , Ridha Basil H. , Schmierer Klaus , Siddique Durre , Thornton John S. , Wroe Stephen J. , Fox Nick C. 
Published: December 2007

AbstractThere is increasing interest in imaging cadavers for noninvasive autopsies for research purposes. However, the temperature is well below that of in vivo imaging, and a variety of interesting ‘cold brain’ effects are observed. At lower temperatures conventional FLAIR sequences no longer produce dark cerebrospinal fluid (CSF);T1is reduced from about 4.0 sec in vivo to 1.7 sec at 1°C. The diffusion coefficient (DC) of CSF is much reduced (from 3.1 10−9m2s−1in vivo to 1.1 at 1°C). DC values therefore provide a noninvasive thermometer to measure brain core temperature to within 1.0°C. In three cadavers DC values were 1.1–1.5 10−9m2s−1, indicating brain core temperatures of 1–10°C, consistent with external thermocouple measurements. An improved inversion time (TI0) can then be found for FLAIR. At 10°C this Cold FLAIR sequence (TI0= 1.5 sec) gave black CSF. Expressions for CSF DC andT1as a function of temperature were produced. A measurement of CSF DC could be converted directly to temperature and the required TI0found. In vitro values of CSF DC were about 1% lower than that of water. Thus, FLAIR imaging can be optimized for cadaveric brains at low and unknown temperatures, thereby improving value for autopsy purposes and facilitating comparisons with in vivo imaging. Magn Reson Med, 2007. © 2007 Wiley‐Liss, Inc.
Debt, democratization, and development in Latin America: How policy can affect global warming
Authors: Aubourg René W. , Good David H. , Krutilla Kerry 
Published: December 2007

AbstractThe environmental Kuznets curve (EKC) hypothesis conjectures a nonlinear relationship between pollution and economic growth, such that pollution per capita initially increases as countries economically develop, but then reaches a maximum point before ultimately declining. Much of the EKC literature has focused on testing this basic hypothesis and, in studies that find evidence of an EKC, estimating the “turning point” level of development at which the per capita pollution‐growth relationship changes sign. This approach has not emphasized the policy relevance of specification issues or the potential role of policy variables. This research explores a modified EKC specification which conditions the pollution‐growth relationship on a country's level of debt and degree of democratization. These variables turn out to be significant, implying that different political and economic contexts can shift EKCs and their turning points. These findings suggest that policies to relieve debt burdens and institute political reform, in addition to their usual justifications, also could be used as a strategy to reduce carbon emissions from developing countries. © 2008 by the Association for Public Policy Analysis and Management.
Natural rubber filled SiC and B4C ceramic composites as a new NTC thermistors and piezoresistive sensor materials
Authors: Todorova Z. , Dishovsky N. , Dimitrov R. , El‐Tantawy Farid , Abdel Aal N. , Al‐Hajry A. , Bououdina M. 
Published: December 2007

AbstractA novel electrically conductive composite for NTC thermistor and piezoresistive sensor was successfully fabricated by homogeneously dispersing conductive SiC and B4C in an insulating natural rubber (NR) matrix. The morphology of the composites was investigated by means of scanning electron microscopy, cross linking density (n), volume fraction of rubber (Vr), and interparticle distance among conductive phases (rp). The influence of the filler concentrations on the mechanical properties such as modulus of elasticity (E); hardness shore A (H), and elongation at break (EB) were studied in details. The dependences of volume resistivity of NR based composites filled with B4C and SiC as a function of fillers concentration was investigated. Temperature dependencies of volume resistivity were also measured to examine the possible application of the composites to polymer linear negative temperature (NTC) thermistors. Furthermore, the temperature dependencies of dielectric constant of the composites were studied. For practical application, the thermal stability of the composites was examined by means of resistivity temperature and pressure hysteresis cycle. In parallel, the conduction mechanism of conductivity of the composites was interpreted in terms of the computed the activation and hopping energy. The applicability of the composites to piezoresistive sensor was examined too. The good mechanical properties and thermal stability of NR composites behavior can be utilized for fabricating various electronic devices as NTC thermistors and piezoresistive sensor (i.e. transducers in pressure sensors). POLYM. COMPOS., 29:109–118, 2008. © 2007 Society of Plastics Engineers
Analytical and experimental evaluation of elastic properties of vacuum assisted resin infusion molded polymer composites with eight‐harness woven fiber mats
Authors: Khattab Ahmed , El‐Gizawy A. Sherif 
Published: December 2007

AbstractAn analytical and experimental evaluation of elastic properties of composite materials under tensile load is presented in this paper. The analysis focuses on composite materials molded by vacuum assisted resin infusion molding (VARIM). The molded composite structure consists of AS4‐8 harness carbon fiber mats and a high‐temperature polymer (5250‐4‐RTM). The analytical model presented is adapted and formulated using optical microscopy observations of cross sections of samples molded by VARIM. Effects of resin degree of cure, fiber undulation, and resin rich areas between fiber bundles are addressed in the model. An experimental case study is presented to evaluate the accuracy of the adapted analytical model. The evaluation shows a reasonable agreement between the experimental and analytical results. POLYM. COMPOS., 29:63–71, 2008. © 2007 Society of Plastics Engineers
Synthesis of chitin calcium phosphate composite in different growth media
Authors: Geçer Aylin , Yıldız Nuray , Erol Murat , Çalımlı Ayla 
Published: December 2007

AbstractThis paper presents some results concerning chitin calcium phosphate composites obtained in different growth media. The synthesis of chitin calcium phosphate composite was carried out by phosphorylation, calcification, and soaking in different calcium phosphate growth media. This research is focused on studying and understanding the effect of using different growth media on composite samples. Hydroxyapatite was determined in the composite samples synthesized by using both simulated body fluid (SBF) and calcium phosphorus tris (Ca‐PTris) solution. Calcium/phosphorus (Ca:P) ratio of the composite synthesized by using SBF was found higher than that of composite synthesized by using Ca‐PTris solution as calcium phosphate growth media. The Ca:P ratio of the composite (1.72) immersed in 1.5× SBF for 35 day is similar to the theoretical value of hydroxyapatite (1.67) and closer to the theoretical value of human bone (1.75). POLYM. COMPOS., 29:84–91, 2008. © 2007 Society of Plastics Engineers
Acid catalyzed intramolecular attack of β‐phenylthioureido group on amide function. Parallel formation of thiodihydrouracil and 4‐iminothiodihydrouracil. Different pathways in the Edman degradation reaction in the formation of six‐ versus five‐membered cyclic intermediates
Authors: Pojarlieff Ivan G. , Blagoeva Iva B. , Toteva Maria M. , Atay Ergun , Angelova Violina T. , Vassilev Nikolay G. , Koedjikov Asen H. 
Published: December 2007

AbstractContrary to the cleavage of α‐phenylthioureido peptides 1 proceeding through intermediate 2‐anilinothiazolinone 2, the b‐analog cis‐2‐(3‐phenylthioureido)cyclopentane‐carboxamide 5 forms transiently 4‐imino‐2‐thioxopyrimidine 6. Monitoring amide cyclization and hydrolysis of iminopyrimidine 6 in acid by UV showed that an equilibrium between 5 and 6 was reached followed by slower conversion of both compounds into 2‐oxo‐4‐thioxopyrimidine 7. Both processes were characterized by isosbestic points, the first due to parallel conversion of 5 into 6 and 7 (or 6 into 5 and 7) at a constant ratio while the second identical for both reactants – to conversion of equilibrated 5 and 6 into 7. The special isosbestic points allowed the determination of the individual constants of Scheme 2. Further confirmation was obtained from NMR product analysis and following the cyclization of amide 5 in DMSO:DCl. Product 2‐oxo‐4‐ thioxopyrimidine 7 hydrolyzed reversibly to thioureido acid 8. The cyclization rate of 8 allowed the participation of 6‐oxothiazine 10 formed by sulfur attack to be excluded. The absence of sulfur attack in the six‐membered case is explained by the longer CS bond bringing about greater bond angle strain at the tetrahedral ring atoms due to the geometrical characteristics of five‐ and six‐membered rings with planar segments. The cyclizations of amide 5 to iminopyrimidine 6 and to thiodihydrouracil 7 are first order in [H+], while the reactions of protonated imine 6H+ are zero order to amide and −1 to thiodihydrouracil. The reaction orders can be reconciled by assuming a rate determining proton transfer from the tetrahedral intermediate in amide cyclization. Copyright © 2007 John Wiley & Sons, Ltd.
Deprotonation and radicalization of glycine neutral structures
Authors: Yang Gang , Zu Yuangang , Zhou Lijun 
Published: December 2007

AbstractAb initio calculations at MP2/6‐311++G(d,p) theoretical level were performed to study the deprotonation and radicalization processes of 13 glycine neutral structures (A. G. Császár, J. Am. Chem. Soc. 1992; 114: 9568). The deprotonation processes to glycine neutral structures take place at the carboxylic sites instead of α‐C or amido sites. Two carboxylic deprotonated structures were obtained with the deprotonation energies calculated within the range of 1413.27–1460.03 kJ · mol−1, which are consistent with the experimental results. However, the radicalization processes will take place at the α‐C rather than carboxylic O or amido sites, agreeing with the experimental results. Seven α‐C radicals were obtained with the radical stabilization energies calculated within the range of 44.87–111.78 kJ · mol−1. The population analyses revealed that the main conformations of the neutral or radical state are constituted by several stable structures, that is, the other structures can be excluded from the future considerations and thus save computational resources. Copyright © 2007 John Wiley & Sons, Ltd.
Reaction of poly‐L‐lysine with aryl acetates and aryl methyl carbonates. A mechanistic study
Authors: Castro Enrique A. , Echevarria Gerardo R. , Opazo Alejandra , Robert Paz S. , Santos José G. 
Published: December 2007

AbstractThe pH profile (log k vs. pH) of the reactions of poly‐L‐lysine (PL) with a series of aryl acetates and aryl methyl carbonates in aqueous solution show the same conformational changes as those determined by potentiometric titrations. When PL is a random coil, the most probable mechanism for the reactions studied is through the formation of a tetrahedral intermediate and its breakdown to products as the rate‐determining step. The tetrahedral intermediate is stabilized by a hydrogen bond interaction between the nitro groups in the substrate and the NH group of the principal chain or some NH2 groups of the lateral chains. Copyright © 2007 John Wiley & Sons, Ltd.
Structural and spectroscopic investigations of non‐planar tris(dialkylamino)cyclopropenium cations
Authors: Butchard James R. , Curnow Owen J. , Pipal Robert J. , Robinson Ward T. , Shang Rong 
Published: December 2007

AbstractThe mixed triaminocyclopropenium cation bis(diisopropylamino)dimethylaminocyclopropenium was prepared from bis(diisopropylamino)chlorocyclopropenium by reaction with dimethylamine. It was isolated as the perchlorate salt and found to have a distorted structure in the solid state. Tris(diisopropylamino)cyclopropenium was prepared by reaction of pentachlorocyclopropane with diisopropylamine in a refluxing dichloroethane solution for 2 days. The solid state structure was found by X‐ray crystallography to have two planar amino groups and one pyramidal amino group, however, the 1H‐NMR and infrared solution spectra show equivalent isopropyl groups in solution. The compounds were also characterised by Raman and infrared spectroscopy. Additionally, a new polymorph of [C3(NMe2)3]ClO4 is described as well as the X‐ray structure of bis(diisopropylamino)cyclopropenone. Copyright © 2007 John Wiley & Sons, Ltd.
Is corannulene a better diene or dienophile? A DFT analysis
Authors: Jayapal Prabha , Sundararajan Mahesh , Rajaraman Gopalan , Venuvanalingam Ponnambalam , Kalagi Rashmi , Gadre Shridhar R 
Published: December 2007

AbstractDiels Alder reactivity of corannulene has been probed using density functional theory (DFT) at B3LYP/6‐31G* level by employing it both as a diene and a dienophile in cycloaddition with ethylene and 1,3‐butadiene as typical partners. Computations reveal that corannulene acts better as a dienophile than as a diene and as a dienophile it undergoes normal electron demand type addition with 1,3‐butadiene, and as a diene corannulene undergoes inverse electron demand type addition with ethylene. When employed as a dienophile the addition takes place preferentially in the rim position than in the spoke position due to strong steric and electronic reasons. Further in the rim addition rim exo approach is favored kinetically and thermodynamically. As a diene, corannulene shows regioselectivity for rim–spoke addition over spoke–spoke addition. Concerted type cycloadditions have been studied and the reactions are seen to take place preferentially on the convex face. The effect of substituents in butadiene on the reactivity and the reaction of butadiene–pentaindenocorannulene (an extended corannulene) system has been investigated for the most favorable rim exo positions. Copyright © 2007 John Wiley & Sons, Ltd.