bluuebunny/crossref_metadata_2025 huggingface dataset:
Novel cellulose ester–poly(furfuryl alcohol)–flax fiber biocomposites
Authors: Toriz G. , Arvidsson R. , Westin M. , Gatenholm P.
Published: February 2003

Composites based entirely on renewable materials with flax fibers as reinforcement and cellulose acetate butyrate (CAB) as the matrix were prepared by compression molding. Scanning electron microscopy of the fracture surfaces showed insufficient penetration of the matrix into the fiber mat. Rheological measurements indicated that this was caused by the high melt viscosity of CAB. Various amounts of furfuryl alcohol (FA) were added to the matrix to control the melt viscosity of CAB. The melt viscosity was decreased dramatically by the introduction of FA, which acted as a CAB solvent and facilitated the impregnation of the flax fiber mats. The mechanical and dynamic thermal properties of composites based on flax mats and various amounts of CAB and FA were investigated. The addition of FA to CAB and the polymerization of FA resulted in a linearly increased modulus and an increase in the maximum fiber stress (strength) of flax composites but a decreased toughness. Dynamic mechanical thermal analysis (DMTA) showed that CAB/poly(furfuryl alcohol) (PFA) matrices were miscible because the glass‐transition temperature (Tg) in the resulting blends occurred between the Tg of the homopolymers. DMTA also showed that increasing the amount of FA in the matrix substantially increased the storage modulus of the composites at temperatures lower than 80°C. It was possible to tune the storage properties of the composites through the addition of appropriate amounts of FA to the matrices. The CAB/PFA matrix showed behavior between that of thermoplastics and thermosets because of the miscibility and affinity of its components. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 337–345, 2003
Spectroscopic behavior of poly(vinyl alcohol) films with different molecular weights after UV irradiation, thermal annealing, and double treatment with UV irradiation and thermal annealing
Authors: Abd El‐Kader Kamal M.
Published: February 2003

Pure poly(vinyl alcohol) (PVA) films with molecular weights 5,000, 72,000, and 125,000 g/mole were prepared by casting technique. The thickness of prepared samples was 0.21 mm. Xenon arc lamp was used to irradiate two samples from each molecular weight at 400 W for 5 min. One from each irradiated PVA samples was heated at 423 K for 2 h. An additional PVA sample unirradiated from each molecular weight was heated at 423 K for 2 h. Optical absorption measurements have been carried out in the wavelength range of 190–900 nm for untreated, UV‐irradiated, heated, and double‐treated samples by UV irradiation and heat. The double‐treated PVA samples with molecular weights 5,000 and 72,000 g/mole showed approximately zero transmission in comparison with untreated PVA sample in the wavelength range of 190–320 nm. PVA sample with 125,000 g/mole was irradiated with 600 W for 5 min to obtain the zero transmission in the same wavelength range. Identification of the structure and assignments of energy bands were studied also by using FTIR. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 589–594, 2003
Effect of film draw temperature (FDT) on physical properties of polyethylene
Authors: Basfar A. A. , Idriss Ali K. M.
Published: February 2003

Thin polymer films (0.06 mm thick) were prepared with LLDPE (coded as A) and LDPE (coded as D) at different film draw temperatures (FDTs) from 5 to 65°C. There was about a 42% enhancement of the tensile strength when the LLDPE film was drawn at 45°C and LDPE at 35°C and the ultimate elongation increased between 14 and 32%. When various additives were incorporated into these resins A and D, the tensile strength slightly decreased, but the ultimate elongation increased. Films which attained the highest tensile properties showed the maximum resistance against degradation by natural outdoor weathering. Although irradiation of these films by a gamma source caused reduction of their tensile properties, there was a general tendency of resisting this reduction with increase of the FDT. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 459–465, 2003
Effect of concentration and pH of solutions on the absorbency of polyacrylate superabsorbents
Authors: Kang Hongmei , Xie Jianjun
Published: February 2003

Polyacrylate superabsorbent (PAS) was synthesized by aqueous solution polymerization crosslinked by N,N‐methylene bisacrylamide. The effect of pH and concentration of several solutions on absorbency (Q) of PAS was studied. The results showed that the absorbency increased at first and then decreased with the increase of the solution's pH; the summit of the absorbing curve was attained when pH was about 6.25. The relation between absorbency and pH could be represented by a quadratic equation and the square difference was relatively small. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 494–499, 2003
Measurement and numerical simulation of three‐dimensional fiber orientation states in injection‐molded short‐fiber‐reinforced plastics
Authors: Lee Kwang Seok , Lee Seok Won , Chung Kwansoo , Kang Tae Jin , Youn Jae Ryoun
Published: February 2003

To determine three‐dimensional fiber orientation states in injection‐molded short‐fiber composites, a confocal laser scanning microscope (CLSM) is used. Since the CLSM optically sections the specimen, more than two images of the cross sections on and below the surface of the composite can be obtained. Three‐dimensional fiber orientation states can be determined by using geometric parameters of fiber images obtained from two parallel cross sections. For experiments, carbon‐fiber‐reinforced polystyrene is examined by the CLSM and geometric parameters of fibers on each cross‐sectional plane are measured by an image analysis. In order to describe fiber orientation states compactly, orientation tensors are determined at different positions of the prepared specimen. Three‐dimensional orientation states are obtained without any difficulty by determining the out‐of‐plane angles utilizing fiber images on two parallel planes acquired by the CLSM. Orientation states are different at different positions and show the shell–core structure along the thickness of the specimen. Fiber orientation tensors are predicted by a numerical analysis and the numerically predicted orientation states show good agreement with measured ones. However, some differences are found at the end of cavity. They may result from the fountain flow effects, which are not considered in the numerical analysis. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 500–509, 2003
Heterogeneous nucleation of nylon 6 and PET with selected inorganic compounds
Authors: Martínez‐Vázquez D. G. , Medellín‐Rodríguez F. J. , Phillips P. J. , Sanchez‐Valdes S.
Published: February 2003

The effect of several inorganic compounds in the heterogeneous nucleation of poly(ethylene terephthalate) (PET) and poly(caprolactam) (nylon 6) was studied. Six inorganic chemicals were specifically selected, on the basis of their crystal structure, basal lattice dimensions, and thermal properties, in order to study the effect of temperature in their nucleation capabilities. Considering that temperature is one of the most important variables involved during processing of thermoplastics, the impact of the nucleation ability of the intentionally added heterogeneities was studied in terms of thermal conductivity, thermal expansion, and heat capacity. Six inorganic chemicals, which crystallize in the cubic system, were selected considering that they had variations in one of the thermal properties while the others remained practically constant along the temperature range of interest. The results indicated that, at constant surface area, chemical compounds with lower overall values of thermal expansion and also those with overall higher values of heat capacity promote heterogeneous nucleation; the effect of heat capacity was, however, also found potentially related to a different intrinsic mechanism. The impact of thermal conductivity was not considered significant. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 360–368, 2003
Development of a new instrument for rheumatoid arthritis: The Cedars‐Sinai Health‐Related Quality of Life instrument (CSHQ‐RA)
Authors: Weisman Michael H. , Paulus Harold D. , Russak Simcha M. , Lubeck Deborah P. , Chiou Chiun‐Fang , Sengupta Nishan , Ofman Joshua J. , Borenstein Jeff , Moadel Alyson B. , Sherbourne Cathy D.
Published: February 2003

Objective

To update and complement existing instruments, we developed a multidimensional disease‐specific instrument, intended to reflect the impact of rheumatoid arthritis (RA) with modern treatment options on patient's Health‐Related Quality of Life (HRQOL).

Methods

Items were developed from a systematic review of published HRQOL measures and transcripts of RA patient focus groups. Items were refined by an expert panel and administered to 350 patients for psychometric testing.

Results

The systematic review identified 228 potential items, and the focus group transcripts identified 96 additional items. Expert review and pilot testing resulted in an initial 58‐item instrument. Twenty‐six items were excluded due to floor/ceiling effects, poor response rates, or high item‐item correlations. Factor analysis identified a 5‐factor structure (eigenvalues ≥1). Multi‐trait scaling performed on both completed surveys confirmed the 5 sub‐scale structure (Cronbach's > 0.87).

Conclusion

The CSHQ‐RA consists of 33 items that address 5 HRQOL domains, each with high internal consistency. Additional testing will assess the instrument's validity and responsiveness.
Disease activity score for children with juvenile dermatomyositis: Reliability and validity evidence
Authors: Bode Rita K. , Klein‐Gitelman Marisa S. , Miller Michael L. , Lechman Toula S. , Pachman Lauren M.
Published: February 2003

Objective

To assess the reliability and validity of the Disease Activity Score (DAS), an instrument used to evaluate children with juvenile dermatomyositis (JDM).

Methods

Psychometric study of internal consistency, reliability, rater agreement, and the relationship with measures of muscle strength and disability was conducted.

Results

The DAS ratings are internally consistent (reliability = 0.89) and describe a wide range of disease activity. The pediatric rheumatologists in this study agree on the presence of most of the disease indicators. Their disagreements tend to cancel each other, resulting in highly correlated (r = 0.79) overall measures across raters. Estimates of muscle weakness using the DAS and ratings of muscle strength obtained independently from therapists are highly related (r = −0.77), but estimates of disease activity and disability are weakly related (r = 0.20).

Conclusion

The DAS exhibits evidence of good reliability and validity. The combination of skin and muscle strength assessments makes this easily administered instrument a useful addition in the evaluation of children with JDM.
Computing the transition state populations in simple protein models
Authors: Ozkan S. Banu , Dill Ken A. , Bahar Ivet
Published: February 2003

We describe the master equation method for computing the kinetics of protein folding. We illustrate the method using a simple Go model. Presently most models of two‐state fast‐folding protein folding kinetics invoke the classical idea of a transition state to explain why there is a single exponential decay in time. However, if proteins fold via funnel‐shaped energy landscapes, as predicted by many theoretical studies, then it raises the question of what is the transition state. Is it a specific structure, or a small ensemble of structures, as is expected from classical transition state theory? Or is it more like the denatured states of proteins, a very broad ensemble? The answer that is usually obtained depends on the assumptions made about the transition state. The present method is a rigorous way to find transition states, without assumptions or approximations, even for very nonclassical shapes of energy landscapes. We illustrate the method here, showing how the transition states in two‐state protein folding can be very broad ensembles. © 2002 Wiley Periodicals, Inc. Biopolymers 68: 35–46, 2003
Penile neuronal nitric oxide synthase and its regulatory proteins are present in hypothalamic and spinal cord regions involved in the control of penile erection
Authors: Ferrini Monica G. , Magee Thomas R. , Vernet Dolores , Rajfer Jacob , González‐Cadavid Nestor F.
Published: February 2003

Control of penile erection requires the coordination of the hypothalamus and the L6–S1 region of the spinal cord. Erection requires the activation of neuronal nitric oxide synthase (nNOS), which is tightly regulated. Because variants of nNOS (penile nNOS: PnNOS) and the N‐methyl‐D‐aspartate receptor (truncated NMDAR subunit 1: NMDAR1‐T) as well as protein inhibitor of NOS (PIN) have all been located in the pelvic ganglia and penile nerves, this work aims to determine whether these proteins are also present in the hypothalamus. It was found that PnNOS, the brain‐type nNOS, and PIN, were expressed in the hypothalamus. In contrast, NMDAR1‐T was expressed only in the penis, whereas the brain‐type NMDAR1 was present in the brain and sacral spinal cord and not in the penis. PnNOS was found in the media preoptic area, posterior magnocellular, and the parvocellular regions of the paraventricular nucleus, supraoptic nucleus, septohypothalamic nucleus, medial septum, cortex, and in some of the nNOS staining neurons throughout the brain. It was absent in the organum vasculosum of the lamina terminalis. PIN staining was present in neurons of the medial preoptic area, paraventricular nucleus, medial septum, and cortex, but not in the supraoptic nucleus, septohypothalamic nucleus, or organum vasculosum of the lamina terminalis. Colocalization between PnNOS and PIN was found in the medial preoptic area, medial septum, and cortex, and less in the paraventricular nucleus. PnNOS and oxytocin were colocalized in the paraventricular nucleus and supraoptic nucleus. In hypothalamic extracts, recombinant PIN‐GST protein bound to PnNOS in the extracts and partially inhibited NOS activity. These results indicate that both nNOS variants, and their respective regulatory proteins are present and colocalize in the hypothalamic and spinal cord regions involved in penile erection. J. Comp. Neurol. 458:46–61, 2003. © 2003 Wiley‐Liss, Inc.
Intraneuronal localization of Nogo‐A in the rat
Authors: Jin Wei‐Lin , Liu Ying‐Ying , Liu Hui‐Ling , Yang Hao , Wang Ying , Jiao Xi‐Ying , Ju Gong
Published: February 2003

Nogo‐A is known to be a myelin‐associated protein with strong inhibitory effect on neurite outgrowth and has been considered one of the major factors that hinder fiber regeneration in the central nervous system. Recent studies have demonstrated widespread occurrence of nogo‐A mRNA and Nogo‐A protein in neurons. Our concurrent immunohistochemical study substantiated the widespread distribution of neuronal Nogo‐A. The present study was thus focused on its intraneuronal distribution in the central nervous system, using Western blotting, immunohistochemical, and immunogold electron microscopic techniques. Western blotting of the nucleus, cytoplasm, and membrane subcellular fractions of the cerebellum and spinal cord tissues demonstrated that all three fractions contained Nogo‐A. Nogo‐A immunoreactivity could be identified under confocal microscope in the nucleus, perikayon, and proximal dendrite and along the cell membrane. Under the electron microscope, the perikaryonal Nogo‐A immunogold particles were mainly distributed at polyribosomes and rough endoplasmic reticulum, suggesting its relationship with translation process. The immunogold particles could also be found beneath or on the plasma membrane. In the nucleus, the Nogo‐A immunogold particles were found to be localized at the chromatins of the nucleus, indicating its possible involvement in gene transcription. The presence of Nogo‐A in the nucleus was further supported by transfection of COS‐7L cells with nogo‐A. This study provides the first immunocytochemical evidence for intraneuronal distribution of Nogo‐A. Apparently, the significance of Nogo‐A in the central nervous system is far more complex than what has been envisioned. J. Comp. Neurol. 458:1–10, 2003. © 2003 Wiley‐Liss, Inc.
Role of EphA4 in defining the position of a motoneuron pool within the spinal cord
Authors: Coonan Jason R. , Bartlett Perry F. , Galea Mary P.
Published: February 2003

The correct assembly of the neural circuits that control movement requires the development of topographically organized pools of motoneurons within the spinal cord. The generation of a diverse array of motoneuron subtypes, which express differing transcription factors and cell‐surface receptors, allows different motoneuron pools to be segregated to specific positions during development. In this investigation, we show that the Eph receptor tyrosine kinase, EphA4, appears to be important for the correct localization of a motoneuron pool to a specific position in the spinal cord. In the spinal cord of mice deficient in EphA4, the motoneuron pool that innervates the tibialis anterior muscle of the hindlimb is caudally displaced by approximately one vertebral segment. However, despite the abnormal position of the tibialis anterior motoneuron pool in the spinal cord of EphA4‐deficient animals, the motoneurons of this pool still project to the tibialis anterior muscle of the hindlimb correctly. Additional analyses of other limb innervating motoneuron pools in the cervical and lumbar enlargements of the spinal cord of EphA4‐deficient animals revealed them to be located in the appropriate segmental positions. Furthermore, we show that EphA4 does not appear to be important for spinal motoneuron survival as stereological quantification of the number of motoneurons present in the sciatic motoneuron pool of EphA4‐deficient animals demonstrated these motoneurons to be present in the correct numbers. These observations suggest an important role for EphA4 in regulating the position of a specific motoneuron pool within the spinal cord. J. Comp. Neurol. 458:98–111, 2003. © 2003 Wiley‐Liss, Inc.
Heat transfer enhancement in round tube using wire coil: Influence of length and segmentation
Authors: Shoji Yukitsugu , Sato Kyozo , Oliver D.R.
Published: February 2003

Experiments are performed to study heat transfer enhancement in a round tube using a wire coil as a turbulator. This paper presents the effects of length and segmentation of the wire coil. Experiments are conducted with three different wire coils (1000, 500, and 300 mm) on the effect of length. The wire coils used to measure the effect of segmentation are three different types but of the same area (500 mm × 1, 100 mm × 5, and 50 mm × 10). The wire coils are made of copper of diameter 1.5 mm. The test fluid is water. Both heat transfer and friction factor are measured and compared.

From the experiments, we were able to conclude that heat transfer and friction positively correlate to length of the wire coil. Heat transfer correlations are given as Eq. (7) for length and Eq. (10) for segmentation. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(2): 99–107, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.10072
Numerical simulation on liquid jet behavior issued into still air
Authors: Inamura Takao , Tsutagawa Takehito , Cho Seong Jin , Masuya Goro
Published: February 2003

Numerical simulations have been conducted to clarify the effects of turbulence, in the onset of protrusions on liquid jet surfaces. The turbulences in the liquid jet were simulated by the Rankin vortices. The liquid jet surface was tracked numerically by the VOF method. From numerical simulations, the protrusions on the liquid jet surface are induced by the vortices in the liquid, whose rotational direction decelerates the jet surface. Despite the distance between vortices, the displacement of the liquid jet surface from the initial surface location increases linearly, in time, at almost the same growth rate. In the initial region, the growth rate of the displacement increases as the major semiaxis‐to‐minor semiaxis ratio of the ellipsoidal vortex increases. The initial growth rate of displacement is almost proportional to the vortex intensity. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(2): 141–152, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.10078
Enhancement of natural convective heat transfer from tall, vertical heated plate to water
Authors: Misumi Toshiyuki , Kitamura Kenzo
Published: February 2003

An enhancement technique was developed for natural convection heat transfer from a tall, vertical heated plate to water. Rectangular grid fins attached to the base plate were utilized as a heat transfer promoter. These grid fins redirect the high‐temperature fluid ascending along the base plate toward the outside of the boundary layer and introduce the low‐temperature ambient fluid toward the base plate instead. The heat transfer coefficients of thus‐treated surfaces were measured and compared with a nontreated surface and a surface with conventional vertical plate‐fins. The highest performance was achieved for the experimental surfaces. In particular, the experimental surfaces with 5‐mm‐high, nonconducting grids and with 10‐mm‐high, conducting grid fins show 27% and 80% higher heat transfer coefficients compared to the turbulent heat transfer coefficients of the nontreated surface, respectively. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(2): 178–190, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.10083
Rapid screening and characterization of drug metabolites using a new quadrupole–linear ion trap mass spectrometer
Authors: Hopfgartner Gérard , Husser Christophe , Zell Manfred
Published: February 2003

The application of a new hybrid RF/DC quadrupole–linear ion trap mass spectrometer to support drug metabolism and pharmacokinetic studies is described. The instrument is based on a quadrupole ion path and is capable of conventional tandem mass spectrometry (MS/MS) as well as several high‐sensitivity ion trap MS scans using the final quadrupole as a linear ion trap. Several pharmaceutical compounds, including trocade, remikiren and tolcapone, were used to evaluate the capabilities of the system with positive and negative turbo ionspray, using either information‐dependent data acquisition (IDA) or targeted analysis for the screening, identification and quantification of metabolites. Owing to the MS/MS in‐space configuration, quadrupole‐like CID spectra with ion trap sensitivity can be obtained without the classical low mass cutoff of 3D ion traps. The system also has MS3 capability which allows fragmentation cascades to be followed. The combination of constant neutral loss or precursor ion scan with the enhanced product ion scan was found to be very selective for identifying metabolites at the picogram level in very complex matrices. Owing to the very high cycle time and, depending on the mass range, up to eight different MS experiments could be performed simultaneously without compromising chromatographic performance. Targeted product ion analysis was found to be complementary to IDA, in particular for very low concentrations. Comparable sensitivity was found in enhanced product ion scan and selected reaction monitoring modes. The instrument is particularly suitable for both qualitative and quantitative analysis. Copyright © 2003 John Wiley & Sons, Ltd.
Rapid quantification of HIV protease inhibitors in human plasma by high‐performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry
Authors: Crommentuyn K. M. L. , Rosing H. , Nan‐Offeringa L. G. A. H. , Hillebrand M. J. X. , Huitema A. D. R. , Beijnen J. H.
Published: February 2003

HIV protease inhibitors are important antiretroviral drugs which have substantially reduced the morbidity and mortality associated with HIV‐1 infection. Recent data have shown relationships between plasma concentrations of the protease inhibitors and clinical response, which makes therapeutic drug monitoring valuable. We have developed and validated an assay, using liquid chromatography coupled with electrospray tandem mass spectrometry (LC/MS/MS), for the routine quantification of the six licensed protease inhibitors (amprenavir, indinavir, lopinavir, nelfinavir, ritonavir and saquinavir) and the pharmacologically active nelfinavir metabolite M8 in plasma.

The sample pretreatment consisted of protein precipitation with a mixture of methanol and acetronitrile using only 100 µl of plasma. Chromatographic separation was performed on an Inertsil ODS3 column (50 × 2.0 mm i.d., particle size 5 µm), with a quick stepwise gradient using an acetate buffer (pH 5) and methanol, at a flow rate of 0.5 ml min−1. The analytical run time was 5.5 min. The use of a 96‐well plate autosampler allowed batch sizes up to 150 patient samples. The triple‐quadrupole mass spectrometer was operated in the positive ion mode and multiple reaction monitoring was used for drug quantification. The method was validated over the concentration ranges 0.01–10 µg ml−1 for indinavir and saquinavir, 0.1–10 µg ml−1 for amprenavir, 0.05–10 µg ml−1 for nelfinavir and ritonavir, 0.1–20 µg ml−1 for lopinavir and 0.01–5 µg ml−1 for M8. Saquinavir‐d5 and indinavir‐d6 were used as internal standards. The coefficients of variation were always <10% for both intra‐day and inter‐day precisions for each compound. Mean accuracies were also between the designated limits (±15%). The validated concentration ranges proved to be adequate in daily practice. This robust and fast LC/MS/MS assay is now successfully applied for routine therapeutic drug monitoring and pharmacokinetic studies in our hospital. Copyright © 2003 John Wiley & Sons, Ltd.
Characterization of oligodendrogliomas using short echo time 1H MR spectroscopic imaging
Authors: Rijpkema M. , Schuuring J. , van der Meulen Y. , van der Graaf M. , Bernsen H. , Boerman R. , van der Kogel A. , Heerschap A.
Published: February 2003

Oligodendroglial tumors may not be distinguished easily from other brain tumors based on clinical presentation and magnetic resonance imaging (MRI) alone. Identification of these tumors however may have therapeutic consequences. The purpose of this study was to characterize and identify oligodendrogliomas by their metabolic profile as measured by 1H MR spectroscopic imaging (MRSI). Fifteen patients with oligodendroglial tumors (eight high‐grade oligodendrogliomas, seven low‐grade oligodendrogliomas) underwent MRI and short echo time 1H MRSI examinations. Five main metabolites found in brain MR spectra were quantified and expressed as ratios of tumor to contralateral white matter tissue. The level of lipids plus lactate was also assessed in the tumor. For comparison six patients with a low grade astrocytoma were also included in the study. The metabolic profile of oligodendrogliomas showed a decreased level of N‐acetylaspartate and increased levels of choline‐containing compounds and glutamine plus glutamate compared with white matter. The level of glutamine plus glutamate was significantly higher in low‐grade oligodendrogliomas than in low‐grade astrocytomas and may serve as a metabolic marker in diagnosis and treatment planning. In high‐grade oligodendrogliomas large resonances of lipids plus lactate were observed in contrast to low‐grade tumors. Copyright © 2003 John Wiley & Sons, Ltd.
Quantification of the glycogen 13C‐1 NMR signal during glycogen synthesis in perfused rat liver
Authors: Bergans N. , Dresselaers T. , Vanhamme L. , Van Hecke P. , Van Huffel S. , Vanstapel F.
Published: February 2003

We studied glycogen synthesis from glucose in perfused livers of fed (n = 4) and 24 h starved (n = 7) rats. Glycogenolysis was inhibited by BAY R3401 (150 µM) and proglycosyn (100 µM). After 60 min, we replaced 99% 13C‐1 glucose by natural abundance glucose. This pulse‐chase design allowed us to recognize residual ongoing futile glycogen turnover from the release of initially deposited 13C‐label, into the 13C‐free chase medium. Net residual turnover was less than 2 ± 0.7% and 0.6 ± 0.2% of 1‐13C glycogen deposition rates of 0.31 ± 0.04 and 0.99 ± 0.04 µmol glucose g−1 min−1, in starved and fed livers, respectively. The 1‐13C glycogen signal was monitored throughout the experiment with proton‐decoupled 13C NMR spectroscopy and analyzed in the time domain using AMARES. We noticed progressive line‐broadening in any single experiment in the chase phase. One or a sum of two to three overlapping Lorentzians, with different exponential damping factors, were fitted to the signal. When the S/N was better than 40, the fit always delivered a small and a broad component. In the chase phase, the fit with a single Lorentzian resulted in a decline of glycogen signal by about 15 ± 4 and 12 ± 2% in starved and fed rats, respectively. This apparent decline in 1‐13C glycogen signal could not be accounted for by the appearance of equivalent amounts of 13C‐labeled metabolites in the perfusate. The fit with a sum of two Lorentzians resulted in a decline of glycogen signal intensity of 7 ± 5 and 5 ± 3% in starved and fed rats, respectively, which reduced the apparent turnover to 8 ± 9% and 6 ± 4%, respectively. Quantification of the growing 13C‐1 glycogen signal requires a model function that accommodates changes in line shape throughout the period under study. Copyright © 2003 John Wiley & Sons, Ltd.
Personality traits and parenting: neuroticism, extraversion, and openness to experience as discriminative factors
Authors: Metsäpelto Riitta‐Leena , Pulkkinen Lea
Published: February 2003

This study used variable‐ and person‐oriented approaches to examine the relationship between personality traits (at age 33) and parenting (at age 36) among 94 mothers and 78 fathers. The SEM revealed that Openness to Experience (O), low Neuroticism (N), and Extraversion (E) were related to parental nurturance; low O to parental restrictiveness; and low N to parental knowledge about the child's activities. Cluster analysis based on the three parenting factors yielded six gender‐related parenting types with distinguishable personality profiles. Authoritative parents (mostly mothers) and emotionally involved parents (mostly fathers), who were high in nurturance and high to moderate in parental knowledge, were high in E and high to moderate in O. Authoritarian parents (mostly fathers) and emotionally detached parents (mostly mothers), who were low in nurturance, high to moderate in restrictiveness, and moderate to low in parental knowledge, were low in O and E. Permissive parents, who were low in restrictiveness and parental knowledge and moderate in nurturance, were high in N, E, and O. Engaged parents, who were high in nurturance, restrictiveness, and parental knowledge, were moderate in all personality traits. Agreeableness and Conscientiousness did not differ between the parenting types. Copyright © 2002 John Wiley & Sons, Ltd.
Solubilization of cellulosomal cellulases by fusion with cellulose‐binding domain of noncellulosomal cellulase engd from Clostridium cellulovorans
Authors: Murashima Koichiro , Kosugi Akihiko , Doi Roy H.
Published: February 2003

Clostridium cellulovorans produces a cellulase complex (cellulosome) as well as noncellulosomal cellulases. In this study, we determined a factor that affected the solubility of the cellulosomal cellulase EngB and the noncellulosomal EngD when they were expressed in Escherichia coli. The catalytic domains of EngB and EngD formed inclusion bodies when expressed in E. coli. On the other hand, both catalytic domains containing the C‐terminal cellulose‐binding domain (CBD) of EngD were expressed in soluble form. Fusion with the CBD of EngD also helped increased the solubility of cellulosomal cellulase EngL upon expression in E. coli. These results indicate that the CBD of EngD plays an important role in the soluble expression of the catalytic domains of EngB, EngL, and EngD. The possible mechanisms of solubilization by fusion of the catalytic domain with the CBD from EngD are discussed. Proteins 2003;50:620–628. © 2003 Wiley‐Liss, Inc.
The role of electrostatic interaction in the molecular recognition of selective agonists to metabotropic glutamate receptors
Authors: Macchiarulo Antonio , Costantino Gabriele , Sbaglia Robert , Aiello Stefania , Meniconi Mirco , Pellicciari Roberto
Published: February 2003

The influence of electrostatic interactions in determining selectivity for individual subtypes of metabotropic glutamate receptors (mGluRs) is evaluated for a small set of agonists by using the program Delphi and the information thus obtained is compared with docking experiments carried out with AutoDock. The evaluation of the electrostatic component of the free energy of binding for L‐Glu, L‐AP4, or S‐PPG to mGluR1, mGluR2, and mGluR4 subtypes allowed for the detection of subtle differences in the electronic properties of the three subtypes, differences that can account for the observed agonist selectivity. Proteins 2003;50:609–619. © 2003 Wiley‐Liss, Inc.
Crystal structure of a hypothetical protein, TM841 of Thermotoga maritima, reveals its function as a fatty acid–binding protein
Authors: Schulze‐Gahmen Ursula , Pelaschier Joanne , Yokota Hisao , Kim Rosalind , Kim Sung‐Hou
Published: February 2003

We determined the three‐dimensional (3D) crystal structure of protein TM841, a protein product from a hypothetical open‐reading frame in the genome of the hyperthermophile bacterium Thermotoga maritima, to 2.0 Å resolution. The protein belongs to a large protein family, DegV or COG1307 of unknown function. The 35 kDa protein consists of two separate domains, with low‐level structural resemblance to domains from other proteins with known 3D structures. These structural homologies, however, provided no clues for the function of TM841. But the electron density maps revealed clear density for a bound fatty‐acid molecule in a pocket between the two protein domains. The structure indicates that TM841 has the molecular function of fatty‐acid binding and may play a role in the cellular functions of fatty acid transport or metabolism. Proteins 2003;50:526–530. © 2003 Wiley‐Liss, Inc.
Protein local structure prediction from sequence
Authors: Hunter Cornelius G. , Subramaniam Shankar
Published: February 2003

A basis set of protein canonical fragments, or centroids, represents the range of local structure found in globular proteins. We develop a methodology to predict centroids from the amino acid sequence. The predictor gives the probability of each centroid in the basis set, at each loci along the backbone. The predictor selects the best‐fit centroid at about 40% of the loci. The predicted probabilities are accurate and can be used to judge the confidence of each centroid prediction. For example, when filtering out centroids with <0.50 probability, the predictor is 65% accurate, although such high‐probability centroids occur at only 28% of the loci. Centroids with high probability can be interpreted as segments that are highly influenced by the amino acid sequence, whereas centroids with low probability can be interpreted as segments that are more likely influenced by tertiary contacts. Low‐resolution, starting point structures, can be generated by fitting the predicted centroids together. Proteins 2003;50:572–579. © 2003 Wiley‐Liss, Inc.
Fine‐grained protein fold assignment by support vector machines using generalized npeptide coding schemes and jury voting from multiple‐parameter sets
Authors: Yu Chin‐Sheng , Wang Jung‐Ying , Yang Jinn‐Moon , Lyu Ping‐Chiang , Lin Chih‐Jen , Hwang Jenn‐Kang
Published: February 2003

In the coarse‐grained fold assignment of major protein classes, such as all‐α, all‐β, α + β, α/β proteins, one can easily achieve high prediction accuracy from primary amino acid sequences. However, the fine‐grained assignment of folds, such as those defined in the Structural Classification of Proteins (SCOP) database, presents a challenge due to the larger amount of folds available. Recent study yielded reasonable prediction accuracy of 56.0% on an independent set of 27 most populated folds. In this communication, we apply the support vector machine (SVM) method, using a combination of protein descriptors based on the properties derived from the composition of n‐peptide and jury voting, to the fine‐grained fold prediction, and are able to achieve an overall prediction accuracy of 69.6% on the same independent set—significantly higher than the previous results. On 10‐fold cross‐validation, we obtained a prediction accuracy of 65.3%. Our results show that SVM coupled with suitable global sequence‐coding schemes can significantly improve the fine‐grained fold prediction. Our approach should be useful in structure prediction and modeling. Proteins 2003;50:531–536. © 2003 Wiley‐Liss, Inc.
Thermal unfolding simulations of apo‐calmodulin using leap‐dynamics
Authors: Kleinjung Jens , Fraternali Franca , Martin Stephen R. , Bayley Peter M.
Published: February 2003

The simulation method leap‐dynamics (LD) has been applied to protein thermal unfolding simulations to investigate domain‐specific unfolding behavior. Thermal unfolding simulations of the 148‐residue protein apo‐calmodulin with implicit solvent were performed at temperatures 290 K, 325 K, and 360 K and compared with the corresponding molecular dynamics trajectories in terms of a number of calculated conformational parameters. The main experimental results of unfolding are reproduced in showing the lower stability of the C‐domain: at 290 K, both the N‐ and C‐domains are essentially stable; at 325 K, the C‐domain unfolds, whereas the N‐domain remains folded; and at 360 K, both domains unfold extensively. This behavior could not be reproduced by molecular dynamics simulations alone under the same conditions. These results show an encouraging degree of convergence between experiment and LD simulation. The simulations are able to describe the overall plasticity of the apo‐calmodulin structure and to reveal details such as reversible folding/unfolding events within single helices. The results show that by using the combined application of a fast and efficient sampling routine with a detailed molecular dynamics force field, unfolding simulations of proteins at atomic resolution are within the scope of current computational power. Proteins 2003;50:648–656. © 2003 Wiley‐Liss, Inc.
Refinement of the ruby luminescence pressure scale
Authors: Holzapfel Wilfried B.
Published: February 2003

A comparison of recent high pressure x-ray diffraction data for diamond and Ta with low pressure ultrasonic data provides a basis for the refinement of the ruby luminescence pressure scale, whereby not only the slope and curvature parameters A=1904 GPa and B=7.665 of the previous scale are changed, but evidence is given for a modified form for the ruby R1 luminescence line shift under pressure with A=1820 GPa, B=14, and an additional parameter C=7.3. This revised ruby pressure scale resolves to a large extent previous discrepancies between equation of state data derived from x-ray measurements on the basis of the currently used ruby scale, on the one hand, and ultrasonic or theoretical studies, on the other hand.
Microstructural evolutions in converting epitaxial Tl2Ba2CaCu2Ox thin films to epitaxial HgBa2CaCu2O6+δ thin films
Authors: Yan S. L. , Fang L. , Aytug T. , Xie Y. Y. , Wu J. Z. , Siegal M. P.
Published: February 2003

Superconducting HgBa2CaCu2O6+δ (Hg-1212) thin films were obtained from Tl2Ba2CaCu2Ox (Tl-2212) precursor films using a cation–exchange process. In this process, Tl cations on the precursor lattice were thermally excited and then replaced with Hg cations. The mechanism of such an atomic perturbation process has presented an interesting topic in material research. This work investigated the evolution of the crystalline structure and surface morphology of the film during such a conversion. It has been found that the Hg-1212 films may inherit epitaxy and surface morphology from their Tl2Ba2CaCu2Ox precursor films at the low perturbation energy limit. Although the c-axis lattice constant was reduced from 1.48 nm for Tl-2212 to 1.27 nm for Hg-1212 during the cation exchange, the in-plane texture of the film remains. The inverse conversion from Hg-1212 to Tl-2212 has also been investigated. Hg-1212 is found to be energetically preferred so that a perturbation above a threshold is required to convert it back to Tl-2212.
The influence of mechanical rubbing on the field-effect mobility in polyhexylthiophene
Authors: Heil H. , Finnberg T. , von Malm N. , Schmechel R. , von Seggern H.
Published: February 2003

This paper reports on improvements of the field-effect mobility in regioregular head-to-tail coupled poly(3-hexylthiophene) based transistors by mechanically induced alignment of polymer chains in the active layer. It is demonstrated that mechanical rubbing perpendicular to the source drain contacts can increase the field-effect mobility up to 800% whereas rubbing parallel to the source drain contacts results in a reduced mobility. The polymer alignment is thereby deduced from optically polarized transmission spectroscopy on polymer-coated quartz glass substrates and is shown to directly correlate with the electrical behavior of a bottom-gate field-effect transistor. The influence of layer thickness on rubbing is investigated and it is shown that annealing after mechanical rubbing at high temperature can further increase the alignment. Differences between thick drop-cast and thin spin-coated films are explained in terms of different solvent evaporation rates, allowing the material to order to a different degree. This interpretation is deduced from characteristic optical and electrical features of the differently prepared poly(3-hexylthiophene) films.
A Lagrangian, integral-density direct formulation and implementation of the analytic CCSD and CCSD(T) gradients
Authors: Hald Kasper , Halkier Asger , Jørgensen Poul , Coriani Sonia , Hättig Christof , Helgaker Trygve
Published: February 2003

Using a Lagrangian formulation an integral-density direct implementation of the analytic CCSD(T) molecular gradient is presented, which circumvents the bottleneck of storing either O(N4) two-electron integrals or O(N4) density matrix elements on disk. Canonical orbitals are used to simplify the implementation of the frozen-core approximation and the CCSD gradient is obtained as a special case. Also a new, simplified approach to (geometrical) derivative integrals is presented. As a first application we report a full geometry optimization for the most stable isomer of SiC3 using the cc-pV5Z basis set with 368 contracted basis functions and the frozen-core approximation.
Ionization energies and spatial volumes of the singly occupied molecular orbital in hydrated magnesium clusters [Mg,nH2O]+
Authors: Reinhard Björn M. , Niedner-Schatteburg Gereon
Published: February 2003

The vertical and adiabatic ionization energies as well as the spatial volumes of the singly occupied molecular orbital (SOMO) of [Mg,nH2O]+, n⩽19, were determined by ab initio calculations. Ionization energies were evaluated from Koopmans’ theorem and explicitly as differences of the total energies of [Mg,nH2O]+ and [Mg,nH2O]2+ as obtained by Hartree–Fock, post-Hartree–Fock and gradient corrected density functional (DFT) methods. In the case of clusters with a sixfold coordinated magnesium cation [Mg(H2O)6,(n−6)H2O]+ Koopmans’ theorem fails for n=6–8,10. In contrast this is a valid approximation for all other cluster sizes. The most stable isomers of [Mg,nH2O]+, n=6–9, exhibit significantly enhanced SOMO volumes. This coincides with a significant drop in ionization energies and with an increase in electron correlation. In these clusters Koopmans’ theorem is a crude approximation due to the neglect of electron correlation. The cluster size dependency of orbital relaxation and change in electron correlation upon ionization allows for an analytical fit in terms of the spatial SOMO volume. Reorganization energies and SOMO volumes indicate strong structural changes in the clusters during ionization due to a significant localization of the SOMO in [Mg,nH2O]+, n<6 and n>8.
Performance of coupled cluster theory in thermochemical calculations of small halogenated compounds
Authors: Feller David , Peterson Kirk A. , de Jong Wibe A. , Dixon David A.
Published: February 2003

Atomization energies at 0 K and heats of formation at 298 K were obtained for a collection of small halogenated molecules from coupled cluster theory including noniterative, quasiperturbative triple excitations calculations with large basis sets (up through augmented septuple zeta quality in some cases). In order to achieve near chemical accuracy (±1 kcal/mol) in the thermodynamic properties, we adopted a composite theoretical approach which incorporated estimated complete basis set binding energies based on frozen core coupled cluster theory energies and (up to) five corrections: (1) a core/valence correction; (2) a Douglas–Kroll–Hess scalar relativistic correction; (3) a first-order atomic spin–orbit correction; (4) a second-order spin–orbit correction for heavy elements; and (5) an approximate correction to account for the remaining correlation energy. The last of these corrections is based on a recently proposed approximation to full configuration interaction via a continued fraction approximant for coupled cluster theory [CCSD(T)-cf]. Failure to consider corrections (1) to (4) can introduce errors significantly in excess of the target accuracy of ±1 kcal/mol. Although some cancellation of error may occur if one or more of these corrections is omitted, such a situation is by no means universal and cannot be relied upon for high accuracy. The accuracy of the Douglas–Kroll–Hess approach was calibrated against both new and previously published four-component Dirac Coulomb results at the coupled cluster level of theory. In addition, vibrational zero-point energies were computed at the coupled cluster level of theory for those polyatomic systems lacking an experimental anharmonic value.
Time-resolved x-ray Raman spectroscopy of photoexcited polydiacetylene oligomer: A simulation study
Authors: Tanaka Satoshi , Volkov Sergei , Mukamel Shaul
Published: February 2003

Off-resonant x-ray diffraction provides a novel real-space and real-time probe of electronic and vibrational dynamics in optically excited molecules. The entire manifold of valence electronic excitations may be monitored through the dependence of the x-ray Raman peaks on the scattering wave vector Δk and energy Δω. The electronic excitation energies and transition density matrices of a polydiacetylene oligomer, computed using the time-dependent Hartree–Fock collective electronic oscillator algorithm, are used to simulate the Raman signals and illustrate their information content.
Spatially resolved spectroscopic strain measurements on high-power laser diode bars
Authors: Tomm J. W. , Gerhardt A. , Müller R. , Malyarchuk V. , Sainte-Marie Y. , Galtier P. , Nagle J. , Landesman J.-P.
Published: February 2003

We compare a number of strain-sensitive spectroscopic techniques, namely, micro-Raman, micro-photoluminescence, photocurrent, and electroluminescence by applying them to two AlGaAs/GaAs high-power diode laser arrays, so-called “cm-bars.” Both devices are fabricated from the same bar batch and considered “identical,” but experienced two different packaging procedures that resulted in different intentionally adjusted “packaging-induced” compressive strains along the array, namely, about −(3.0±0.5)×10−4 and −(5.0±0.7)×10−4 strain difference between edges and centers of the bars. The methods are primarily evaluated with respect to their ability to monitor and quantify the different spatial strain distributions along the devices. In addition their potential for defect detection is demonstrated. Pros and cons of the techniques are summarized and discussed.