bluuebunny/crossref_metadata_2025 huggingface dataset:
Temporospatial expression of placental lactogen and prolactin‐related protein‐1 genes in the bovine placenta and uterus during pregnancy
Authors: Patel O.V. , Yamada O. , Kizaki K. , Todoroki J. , Takahashi T. , Imai K. , Schuler L.A. , Hashizume K.
Published: July 2004

The anatomical location of binucleate cells (BNC) influences protein expression but not steroid synthesis in ruminants. In order to determine if BNC in disparate locations differentially express bovine placental lactogen (bPL) and prolactin‐related protein‐1 (bPRP‐1), we quantitated bPL and bPRP‐1 transcripts in placentomal (cotyledonary, caruncular) and interplacentomal (intercotyledonary, intercaruncular) tissues throughout pregnancy in the bovine using real‐time reverse transcription PCR (RT‐PCR) and in situ hybridization. Levels of both bPL and bPRP‐1 transcripts at peri‐implantation were significantly higher (P < 0.01) in the fetal membrane than in caruncular and intercaruncular tissues. Thereafter, mRNA for these related proteins demonstrated different spatial as well as temporal patterns of expression. Levels of bPRP‐1 transcripts peaked at day 60 of pregnancy. Between day 60 and 100, bPRP‐1 transcripts fell by approximately sevenfold (P < 0.01) in cotyledonary and intercotyledonary tissues, and fourfold in caruncular (P < 0.01) tissue. Levels of bPRP‐1 transcripts remained low in the cotyledonary, intercotyledonary, and caruncular tissues until peripartum. In contrast, bPL expression in placentomes increased with progression of gestation (P < 0.01), but decreased in interplacentomal tissue around peripartum. To conclude, disparate patterns of bPRP‐1 and bPL genes are transcribed in the placentomal and interplacentomal tissues during gestation in the bovine, suggesting that these prolactin‐like hormones serve distinct functions and are regulated differently in the uteroplacental unit in this species. Mol. Reprod. Dev. 69: 146–152, 2004. © 2004 Wiley‐Liss, Inc.
Regulation of histone acetylation during meiotic maturation in mouse oocytes
Authors: Akiyama Tomohiko , Kim Jin‐Moon , Nagata Masao , Aoki Fugaku
Published: July 2004

Histone acetylation is an important epigenetic modification implicated in the regulation of chromatin structure and, subsequently, gene expression. Global histone deacetylation was reported in mouse oocytes during meiosis but not mitosis. The regulation of this meiosis‐specific deacetylation has not been elucidated. Here, we demonstrate that p34cdc2 kinase activity and protein synthesis are responsible for the activation of histone deacetylases and the inhibition of histone acetyltransferases (HATs), respectively, resulting in deacetylation of histone H4 at lysine‐12 (H4K12) during mouse oocyte meiosis. Temporal changes in the acetylation state of H4K12 were examined immunocytochemically during meiotic maturation using an antibody specific for acetylated H4K12. H4K12 was deacetylated during the first meiosis, temporarily acetylated around the time of the first polar body (PB1) extrusion, and then deacetylated again during the second meiosis. Because these changes coincided with the known oscillation pattern of p34cdc2 kinase activity, we investigated the involvement of the kinase in H4K12 deacetylation. Roscovitine, an inhibitor of cyclin‐dependent kinase activity, prevented H4K12 deacetylation during both the first and second meiosis, suggesting that p34cdc2 kinase activity is required for deacetylation during meiosis. In addition, cycloheximide, a protein synthesis inhibitor, also prevented deacetylation. After PB1 extrusion, at which time H4K12 had been deacetylated, H4K12 was re‐acetylated in the condensed chromosomes by treatment with cycloheximide but not with roscovitine. These results demonstrate that HATs are present but inactivated by newly synthesized protein(s) that is (are) not involved in p34cdc2 kinase activity. Our results suggest that p34cdc2 kinase activity induces the deacetylation of H4K12 and that the deacetylated state is maintained by newly synthesized protein(s) that inhibits HAT activity during meiosis. Mol. Reprod. Dev. 69: 222–227, 2004. © 2004 Wiley‐Liss, Inc.
Production of transgenic rats by ooplasmic injection of spermatogenic cells exposed to exogenous DNA: A preliminary study
Authors: Kato Megumi , Ishikawa Ayako , Kaneko Ryosuke , Yagi Takeshi , Hochi Shinichi , Hirabayashi Masumi
Published: July 2004

The aim of the present study was to investigate the efficiencies of producing transgenic rats by the ooplasmic injection of sperm heads (intracytoplasmic sperm injection: ICSI) and elongating spermatids (elongating spermatid injection: ELSI) exposed to the EGFP DNA solution. A slightly lower proportion of ICSI oocytes using sperm heads exposed to a concentration of 0.5 μg/ml DNA solution for 1 min developed into offspring (13.3%, 48/361) when compared to that of oocytes injected with nontreated sperm heads (19.4%, 32/165). Eight ICSI offspring were found to be EGFP‐carrying transgenic rats (16.7% per offspring; 2.2% per embryo). After a 1‐min exposure of the elongating spermatids to 5 μg/ml of DNA solution, 8.8% (45/511) of the ELSI oocytes developed into offspring while 12.7% (22/173) of the ELSI oocytes using nontreated spermatids developed. Six ELSI offspring carried the EGFP DNA (13.3% per offspring; 1.2% per embryo). The conventional pronuclear microinjection of 5 μg/ml of DNA solution resulted in the higher production of offspring (29.7%, 104/350) and the birth of three transgenic rats (2.9% per offspring; 0.9% per embryo). Thus, sperm heads and elongating spermatids were practically useful as the vector of exogenous DNA if the DNA‐exposed spermatogenic cells were microinseminated into rat oocytes. Mol. Reprod. Dev. 69: 153–158, 2004. © 2004 Wiley‐Liss, Inc.
Isolation and characterization of a haploid germ cell specific sperm associated antigen 9 (SPAG9) from the baboon
Authors: Shankar S. , Mohapatra B. , Verma S. , Selvi R. , Jagadish N. , Suri A.
Published: July 2004

Previously, we cloned and sequenced a sperm specific antigen, designated as HSS (EMBL nomenclature human sperm associated antigen 9: hSPAG9) from human testis (Shankar et al.: Biochem Biophys Res Commun 243:561–565, 1998). The present study was conducted to isolate baboon proteomic homologue in order to find out whether the baboon can provide a suitable model for examining its immunocontraception effects. Baboon SPAG9 (bSPAG9) was cloned and sequenced from the baboon testis cDNA library. The baboon cDNA contained open reading frame encoding 760 amino acids. A 90.6 and 96.8% homology between baboon and human SPAG9 was found at protein and DNA levels. Analysis for tissue specificity by Northern blot procedure using various baboon tissues indicated that bSPAG9 was specifically expressed only in the baboon testis. Further, cell type expression analysis by in situ hybridization in baboon testis demonstrated the expression of bSPAG9 mRNA transcript only in the round spermatid suggesting haploid germ cell expression. Anti‐human SPAG9 antibodies recognized the acrosomal compartment region of baboon sperm in indirect immunofluorescence (IIF). Flow cytometry analysis showed surface localization of bSPAG9 in live baboon sperm. The amino acid sequence data for nonhuman primate SPAG9 suggest that antibodies generated by vaccinating baboon with hSPAG9 will recognize nonhuman primate SPAG9, supporting the testing of SPAG9 contraceptive vaccine based on hSPAG9 in the nonhuman primate model. Mol. Reprod. Dev. 69: 186–193, 2004. © 2004 Wiley‐Liss, Inc.
Isolation and characterization of a bovine trophectoderm cell line derived from a parthenogenetic blastocyst
Authors: Talbot Neil C. , Caperna Thomas J. , Powell Anne M. , Garrett Wesley M. , Ealy Alan D.
Published: July 2004

A bovine trophectoderm cell line was established from a parthenogenetic in vitro‐produced blastocyst. To initiate the cell line, 8‐day parthenogenetic blastocysts were attached to a feeder layer of STO fibroblasts and primary outgrowths occurred that consisted of trophectoderm, endoderm, and very occasionally epiblast tissue. Any endoderm and epiblast outgrowths were removed from the primary cultures within the first 10 days of culture by dissection. One of the primary trophectoderm cell cultures was chosen for further propagation and was passaged by physical dissociation and replating on STO feeder cells. The cell culture, designated BPT‐1, was maintained in T25 flasks and passaged at a 1:3 split ratio for the first 15 passages approximately once every 2 weeks. Thereafter, the cell culture was passaged at 1:10–1:40 split ratios. Transmission electron microscopic examination showed the cells to be a polarized epithelium with apical microvilli, a thin basal lamina, and lateral junctions consisting of tight junctions and desmosomes. Lipid vacuoles and digestive vacuoles were also prominent features of the BPT‐1 cells. Metaphase spread analysis at passage 59 indicated a near diploid cell population (2n = 60) with a mode and median of 60 and a mean of 64. BPT‐1 cells secreted interferon‐tau into the medium as measured by anti‐viral assay and Western blot analysis. The cell line provides an in vitro model of parthenogenote trophectoderm whose biological characteristics can be compared to trophectoderm cell lines derived from bovine embryos produced by normal fertilization or nuclear transfer. Mol. Reprod. Dev. 69: 164–173, 2004. © 2004 Wiley‐Liss, Inc.
Exact static element stiffness matrices of non‐symmetric thin‐walled curved beams
Authors: Kim Nam‐II , Yun Hee‐Taek , Kim Moon‐Young
Published: July 2004

An evaluation procedure of exact static stiffness matrices for curved beams with non‐symmetric thin‐walled cross section are rigorously presented for the static analysis. Higher‐order differential equations for a uniform curved beam element are first transformed into a set of the first‐order simultaneous ordinary differential equations by introducing 14 displacement parameters where displacement modes corresponding to zero eigenvalues are suitably taken into account. This numerical technique is then accomplished via a generalized linear eigenvalue problem with non‐symmetric matrices. Next, the displacement functions of displacement parameters are exactly calculated by determining general solutions of simultaneous non‐homogeneous differential equations. Finally an exact stiffness matrix is evaluated using force–deformation relationships. In order to demonstrate the validity and effectiveness of this method, displacements and normal stresses of cantilever thin‐walled curved beams subjected to tip loads are evaluated and compared with those by thin‐walled curved beam elements as well as shell elements. Copyright © 2004 John Wiley & Sons, Ltd.
Accurate stresses in the thin‐layer method
Authors: Kausel Eduardo
Published: July 2004

A method is described by means of which accurate strains and stresses can be obtained for problems of wave motion in laminated media modelled with the thin layer method (TLM), a semi‐discrete procedure that combines the power of finite elements with that of analytical solutions. It is shown that when the displacements in the TLM are combined with the consistent stresses at the layer interfaces, strains and stresses anywhere in the medium can be obtained with the same level of accuracy as the displacements. The proposed method thus circumvents the intrinsic problem that arises when strains are obtained via differentiation. As a bonus, it also renders the stresses continuous across layer interfaces, which is not the case when stresses are obtained via differentiation of the primary interpolation field. Copyright © 2004 John Wiley & Sons, Ltd.
Fatigue life prediction using 2‐scale temporal asymptotic homogenization
Authors: Oskay Caglar , Fish Jacob
Published: July 2004

In this manuscript, fatigue of structures is modelled as a multiscale phenomenon in time domain. Multiple temporal scales are introduced due to the fact that the load period is orders of magnitude smaller than the useful life span of a structural component. The problem of fatigue life prediction is studied within the framework of mathematical homogenization with two temporal co‐ordinates. By this approach the original initial boundary value problem is decomposed into coupled micro‐chronological (fast time‐scale) and macro‐chronological (slow time‐scale) problems. The life prediction methodology has been implemented in ABAQUS and validated against direct cycle‐by‐cycle simulations. Copyright © 2004 John Wiley & Sons, Ltd.
Exposure misclassification as a result of free sample drug utilization in automated claims databases and its effect on a pharmacoepidemiology study of selective COX‐2 inhibitors
Authors: Jacobus Susanna , Schneeweiss Sebastian , Chan K. Arnold
Published: July 2004

Purpose

Free drug samples are widely used in clinical practice. We were concerned about free sample drug utilization as a source of misclassification in pharmacoepidemiology research using claims data that may result in biased effect estimates.

Methods

We investigated the magnitude of potential bias with sensitivity analyses based on a published study that examined cardiovascular risk associated with selective cyclooxygenase 2 (COX‐2) inhibitors. We derived an estimate of free sample drug utilization with market data for rofexcoxib and calculated sensitivity of the exposure ascertainment method using claims data. We corrected the incidence rate ratio assuming the observed unexposed incidence rate was actually a weighted average rate of the truly unexposed and free sample drug users. The impact of exposure misclassification measured as the percentage change from a corrected to the reported crude incidence rate ratio was examined under a range of free sample drug utilization proportions and unexposed cohort sizes.

Results

The proportion of free sample drug utilization of all rofecoxib use in our base case scenario was 15.48%, resulting in sensitivity of 84.52% for exposure ascertainment. The magnitude of bias was an underestimation of the unadjusted incidence rate ratio by 0.03%. With a free sample drug utilization proportion of 1.48% and the same unexposed cohort size of 237 975 person‐years, the underestimation was 0.003%. If the unexposed cohort were 975 person‐years given a 15.48% proportion, the underestimation was 8.82%.

Conclusions

In the pharmacoepidemiology study, we examined that uses claims data to ascertain drug exposure, our results suggest that adjustment for free sample drug utilization is probably not warranted. Copyright © 2004 John Wiley & Sons, Ltd.
Starch‐based nanocomposites by reactive extrusion processing
Authors: Kalambur Sathya B , Rizvi Syed SH
Published: July 2004

Nanocomposites with unique material properties have been prepared from synthetic plastics and nanosilicates (nanoclay) until now, but not from biopolymers such as starch. The primary challenge in making biopolymeric nanocomposites is to achieve strong adhesion between nanoclay and polymer matrix. For the first time nanocomposites with superior properties have been successfully made from starch‐polycaprolactone (PCL) blends in the presence of montmorillonite (MMT) nanoclay. Reactive extrusion results showed that addition of a modified nanoclay at 3 % wt level increased elongation almost fourfold over that of pristine starch–PCL blends. X‐ray diffractions results showed dispersion of clay in the polymer matrix. The nanocomposites have better solvent‐resistance properties because of resistance to diffusion offered by clay platelets in the polymer matrix. Copyright © 2004 Society of Chemical Industry
Comparative study of lignins from ultrasonic irradiated sugar‐cane bagasse
Authors: Sun J‐X , Xu F , Sun X‐F , Sun R‐C , Wu S‐B
Published: July 2004

After ultrasonic irradiation of sugar‐cane bagasse (SCB) in distilled water at 55 °C for 40 min and continuing stirring for 80 min, the irradiated SCB was sequentially treated with 0.5 M NaOH, 0.5 %, 1.0 %, 1.5 %, 2.0 % and 3.0 % H2O2 at pH 11.5, and 2 M NaOH at 55 °C for 2 h, which solubilized 3.3, 59.7, 15.5, 4.4, 5.5, 1.7, 0.6 and 0.6 % of the original lignin, and 13.4, 38.2, 11.9, 4.5, 9.0, 2.4, 1.2, and 11.3 % of the original hemicelluloses, respectively. In total, the sequential extractions resulted in a release of 91.2 % of the original lignin and 91.9 % of the original hemicelluloses, which were higher than in the case of corresponding extractions without ultrasound pre‐treatment. The eight lignin fractions were comparatively characterized by chemical composition, structural features, molecular weights, and thermal stability using alkaline nitrobenzene oxidation, acid hydrolysis, UV, FT‐IR, 1H and 13CNMR spectroscopy, GPC, and thermal analysis. Compared to the lignins obtained without ultrasound, the lignin fractions prepared with the assistance of ultrasound had the same primary structure, composition, and similar or slightly higher purity. Copyright © 2004 Society of Chemical Industry
Platelet adhesion on a polyurethane surface grafted with a zwitterionic monomer of sulfobetaine via a Jeffamine spacer
Authors: Yuan J , Zhu J , Zhu CH , Shen J , Lin SC
Published: July 2004

A possible approach to improve the blood compatibility of poly(ether urethane)s (PU) involves the covalent attachment of key molecules on its surface. The purpose of the present study was to design and synthesise a novel non‐thrombogenic biomaterial by modifying the surface of the PU with a zwitterionic monomer of sulfobetaine via a Jeffamine spacer. In this study, sulfobetaine was grafted onto a PU surface through the following reaction steps: (1) The PU surface was activated with hexamethylene diisocyanate (HDI) in toluene at 50 °C in the presence of di‐n‐butyltin dilaurate (DBTDL) as a catalyst. The extent of the reaction was measured by ATR‐FTIR spectra; a maximum number of free NCO groups was obtained after a reaction time of 90 min. (2) One cap of Jeffamine was reacted with isocyanate groups bound on the surface, so Jeffamine was introduced. (3) The PU surface terminated by Jeffamine was recoupled with isocyanate groups by HDI. (4) The hydroxyl groups of 4‐dimethylamino‐1‐butanol (DMAB) or 2‐dimethylaminoethanol (DMAE) were allowed to react with the isocyanate groups capped on Jeffamine. (5) Sulfobetaines were constructed on the surface through the ring‐opening reaction between tertiary amine and 1,3‐propanesultone (PS). It was confirmed by ATR‐FTIR and XPS that the grafted surfaces were composed of sulfobetaine. The results of the contact‐angle measurements and water absorption showed that they were strongly hydrophilic. The results of this platelet adhesion experiment as a preliminary test showed that PU grafted with sulfobetaine has good blood compatibility featured by the low platelet adhesion. Copyright © 2004 Society of Chemical Industry
Modeling extremely thin absorber solar cells for optimized design
Authors: Taretto K. , Rau U.
Published: July 2004

Extremely thin absorber (ETA) solar cells based on inorganic semiconductors are theoretically analyzed by a model that considers the absorber as being a pin junction, with tunneling‐assisted defect recombination. Tunneling recombination turns out to be very important in ETA solar cells, owing to the high electrical fields in the absorber, which establishes a minimum thickness for the absorber layer, which is calculated to be around 15 and 20 nm for CdTe and CuInS2, respectively. Nevertheless, 15% efficient CdTe and CuInS2 ETA solar cells are possible, even at low diffusion lengths down to 10 nm. Additionally, the modeling provides optimum values for the thickness and number of absorber layers for CdTe and CuInS2 ETA solar cells, as a function of the minority‐carrier diffusion length and diffusion constant, for cells with and without light trapping. The calculations predict that light trapping serves two purposes: to enhance the cell efficiency by up to 5% absolute, and to use a simpler structure compared with the situation without light‐trapping. Copyright © 2004 John Wiley & Sons, Ltd.
Synthesis and photopolymerization of novel multifunctional vinyl esters
Authors: Lee Tai Y. , Kaung W. , Jönsson E. Sonny , Lowery K. , Guymon C. A. , Hoyle C. E.
Published: July 2004

Novel mono‐ and multifunctional vinyl ester monomers containing thioether groups were synthesized via an amine‐catalyzed Michael addition reaction between vinyl acrylate and multifunctional thiols. Using photo‐differential scanning calorimetry and real‐time Fourier transform infrared (RTIR) spectroscopy, the polymerization kinetics and oxygen inhibition of the homopolymerizations of the vinyl ester monomers were investigated. The effect of the vinyl ester and thioether group on acrylate/vinyl ester and thiol/vinyl ester copolymerizations was determined using real‐time IR spectroscopy to monitor polymerization rates of acrylate, vinyl, and thiol groups simultaneously. Polymerization of the vinyl esters used was found to be relatively insensitive to oxygen inhibition. We propose that the thioether group is responsible for reducing oxygen inhibition by a series of chain transfer/oxygen‐scavenging reactions. In polymerization of a acrylate/vinyl ester mixture both in nitrogen and in air, the vinyl ester monomer significantly enhances the polymerization rates and the conversion of the acrylate double bonds via plasticization of the crosslinked matrix and reduction of inhibition by oxygen. Ultimately, the vinyl ester monomer is incorporated into the polymer network. Thiol/vinyl ester free‐radical copolymerization is much faster than either thiol/allylether copolymerization or vinyl ester homopolymerization. The electron‐rich vinyl ester double bonds ensure rapid copolymerization with thiol. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4424–4436, 2004
Kinetic study of the crosslinking reaction of 1,2‐polybutadiene with dicumyl peroxide in the absence and presence of vinyl acetate
Authors: Masaki Kohji , Ohkawara Shin‐ichi , Hirano Tomohiro , Seno Makiko , Sato Tsuneyuki
Published: July 2004

The crosslinking reaction of 1,2‐polybutadiene (1,2‐PB) with dicumyl peroxide (DCPO) in dioxane was kinetically studied by means of Fourier transform near‐infrared spectroscopy (FTNIR). The crosslinking reaction was followed in situ by the monitoring of the disappearance of the pendant vinyl group of 1,2‐PB with FTNIR. The initial disappearance rate (R0) of the vinyl group was expressed by R0 = k[DCPO]0.8[vinyl group]−0.2 (120 °C). The overall activation energy of the reaction was estimated to be 38.3 kcal/mol. The unusual rate equation was explained in terms of the polymerization of the pendant vinyl group as an allyl monomer involving degradative chain transfer to the monomer. The reaction mixture involved electron spin resonance (ESR)‐observable polymer radicals, of which the concentration rapidly increased with time owing to a progress of crosslinking after an induction period of 200 min. The crosslinking reaction of 1,2‐PB with DCPO was also examined in the presence of vinyl acetate (VAc), which was regarded as a copolymerization of the vinyl group with VAc. The vinyl group of 1,2‐PB was found to show a reactivity much higher than 1‐octene and 3‐methyl‐1‐hexene as model compounds in the copolymerization with VAc. This unexpectedly high reactivity of the vinyl group suggested that an intramolecular polymerization process proceeds between the pendant vinyl groups located on the same polymer chain, possibly leading to the formation of block‐like polymer. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4437–4447, 2004
Determining the density profile of confined polymer brushes with neutron reflectivity
Authors: Hamilton W. A. , Smith G. S. , Alcantar N. A. , Majewski J. , Toomey R. G. , Kuhl T. L.
Published: July 2004

Polymer molecules at solid or fluid interfaces have an enormous spectrum of applications in a wide variety of technologies as lubricants, adhesion modifiers, and protective surface coatings. Because polymer brushes have great potential to be used in such applications, there is a need to determine their structure and efficiency in reduced spaces. Using neutron reflectivity, we have directly quantified the density distribution of opposing polymer brushes under confinement in good solvent conditions under confinement. Our measurements show that the density profile in the overlap region between opposing polymer brushes flattens, consistent with predictions from molecular‐dynamics simulations. In addition, a significant increase in the density at the anchoring surfaces due to the collapse of the brush layers was observed. This collapse of the brushes in restricted geometries suggests that high‐density brushes do not interpenetrate significantly under good solvent conditions. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3290–3301, 2004
Using neutron reflectivity to determine the dynamic properties of a copolymer in a homopolymer matrix
Authors: Arlen Michael J. , Dadmun M. D. , Hamilton William A.
Published: July 2004

A protocol for using neutron reflectivity to monitor the dynamic properties of a copolymer in a homopolymer matrix is described. This technique may be used to monitor a broad range of systems, as long as the copolymer and homopolymer form a miscible blend at low copolymer concentrations. Moreover, with knowledge of the Flory–Huggins interaction parameter between the copolymer and homopolymer, the molecular dynamic parameters of the copolymer, such as the tracer diffusion coefficient, segmental friction factor, and longest relaxation time, can be quantitatively determined. This technique is demonstrated by the determination of these parameters for a series of styrene/methyl methacrylate alternating copolymers dispersed in a matrix of deuterated poly(methyl methacrylate). Interestingly, the segmental friction factor of these alternating copolymers is significantly different from that of similar diblock copolymers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3235–3247, 2004
Neutron reflectivity study of glassy polymer brushes in density fluctuating supercritical carbon dioxide
Authors: Koga Tadanori , Ji Y. , Seo Y. S. , Gordon C. , Qu F. , Rafailovich M. H. , Sokolov J. C. , Satija S. K.
Published: July 2004

By using in situ neutron reflectivity, we measured the swelling behavior of two types of polymer brushes, deuterated polystyrene with a trichlorosilane end group and deuterated polystyrene‐block‐poly(4‐vinylpyridine) block copolymer, in supercritical carbon dioxide (scCO2). The measurements were conducted in the pressure range of 0.1–20 MPa at 36 °C. The pressure dependence of the brush height clearly showed an anomalous peak at the density fluctuation ridge (pressure = 8.2 MPa) that defined the maximum long‐range density fluctuation amplitude in the pressure–temperature phase diagram of carbon dioxide (CO2). The density profile of the brush, which could be approximated by a simple step function, and the magnitude of the brush height both indicated that the solvent quality of scCO2 for the deuterated polystyrene brushes was still poor even at the density fluctuation ridge. In addition, atomic force microscopy images for the frozen polystyrene brush prepared by the rapid drying of CO2 showed a phase‐separated structure, as predicted from the numerical calculations of Grest and Murat, as a function of the variable Nσ, where N is the polymerization index and σ is the grafting density. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3282–3289, 2004
An atomic resolution structure for human fibroblast growth factor 1
Authors: Bernett Matthew J. , Somasundaram Thayumanasamy , Blaber Michael
Published: July 2004

A 1.10‐Å atomic resolution X‐ray structure of human fibroblast growth factor 1 (FGF‐1), a member of the β‐trefoil superfold, has been determined. The β‐trefoil is one of 10 fundamental protein superfolds and is the only superfold to exhibit 3‐fold structural symmetry (comprising 3 “trefoil” units). The quality of the diffraction data permits unambiguous assignment of Asn, Gln, and His rotamers, Pro ring pucker, as well as refinement of atomic anisotropic displacement parameters (ADPs). The FGF‐1 structure exhibits numerous core‐packing defects, detectable using a 1.0‐Å probe radius. In addition to contributing to the relatively low thermal stability of FGF‐1, these defects may also permit domain motions within the structure. The availability of refined ADPs allows a translation/libration/screw (TLS) analysis of putative rigid body domains. The TLS analysis shows that β‐strands 6–12 together form a rigid body, and there is a clear demarcation in TLS motions between the adjacent carboxyl‐ and amino‐termini. Although separate from β‐strands 6–12, the individual β‐strands 1–5 do not exhibit correlated motions; thus, this region appears to be comparatively flexible. The heparin‐binding contacts of FGF‐1 are located within β‐strands 6–12; conversely, a significant portion of the receptor‐binding contacts are located within β‐strands 1–5. Thus, the observed rigid body motion in FGF‐1 appears related to the ligand‐binding functionalities. Proteins 2004. © 2004 Wiley‐Liss, Inc.
The B‐ring substituent at C‐7 of colchicine and the α‐C‐terminus of tubulin communicate through the “tail–body” interaction
Authors: Chakraborty Shalmali , Gupta Suvroma , Sarkar Taradas , Poddar Asim , Pena Jose , Solana Rafael , Tarazona Raquel , Bhattacharyya Bhabatarak
Published: July 2004

The carboxy terminals of αβ‐tubulins are flexible regions rich in acidic amino acid residues that play an inhibitory role in the polymerization of tubulin to microtubules. We have shown that the binding of colchicine and its B‐ring analogs (with C‐7 substituents) to tubulin are pH sensitive and have high activation energies. Under identical conditions, the binding of analogs without C‐7 substituents is pH independent and has lower activation energy. β‐C‐terminus‐truncated tubulin (αβs) shows similar pH sensitivity and activation energy to native tubulin (αβ). Removal of the C‐termini of both subunits of tubulin (αsβs) or the binding of a basic peptide P2 to the negatively charged α‐C‐terminus of tubulin causes a colchicine–tubulin interaction independent of pH with a low activation energy. Tubulin dimer structure shows that the C‐terminal α‐tail is too far from the colchicine binding site to interact directly with the bound colchicine. Therefore, it is likely that the interaction of the α‐C‐terminus with the main body of tubulin indirectly affects the colchicine–tubulin interaction via conformational changes in the main body. We therefore conclude that in the presence of tail–body interaction, a B‐ring substituent makes contact with the α‐tubulin and induces significant conformational changes in α‐tubulin. Proteins 2004. © 2004 Wiley‐Liss, Inc.
Crystallographic studies of V44 mutants of Clostridium pasteurianum rubredoxin: Effects of side‐chain size on reduction potential
Authors: Park Il Yeong , Eidsness Marly K. , Lin I‐Jin , Gebel Erika B. , Youn Buhyun , Harley Jill L. , Machonkin Timothy E. , Frederick Ronnie O. , Markley John L. , Smith Eugene T. , Ichiye Toshiko , Kang ChulHee
Published: July 2004

Understanding the structural origins of differences in reduction potentials is crucial to understanding how various electron transfer proteins modulate their reduction potentials and how they evolve for diverse functional roles. Here, the high‐resolution structures of several Clostridium pasteurianum rubredoxin (Cp Rd) variants with changes in the vicinity of the redox site are reported in order to increase this understanding. Our crystal structures of [V44L] (at 1.8 Å resolution), [V44A] (1.6 Å), [V44G] (2.0 Å) and [V44A, G45P] (1.5 Å) Rd (all in their oxidized states) show that there is a gradual decrease in the distance between Fe and the amide nitrogen of residue 44 upon reduction in the size of the side chain of residue 44; the decrease occurs from leucine to valine, alanine or glycine and is accompanied by a gradual increase in their reduction potentials. Mutation of Cp Rd at position 44 also changes the hydrogen‐bond distance between the amide nitrogen of residue 44 and the sulfur of cysteine 42 in a size‐dependent manner. Our results suggest that residue 44 is an important determinant of Rd reduction potential in a manner dictated by side‐chain size. Along with the electric dipole moment of the 43‐44 peptide bond and the 44–42 NHS type hydrogen bond, a modulation mechanism for solvent accessibility through residue 41 might regulate the redox reaction of the Rds. Proteins 2004. © 2004 Wiley‐Liss, Inc.
The electronic structure and magnetic property of metal‐oxo, porphyrin manganese‐oxo, and μ‐oxo‐bridged manganese porphyrin dimer
Authors: Koizumi K. , Shoji M. , Nishiyama Y. , Maruno Y. , Kitagawa Y. , Soda K. , Yamanaka S. , Okumura M. , Yamaguchi K.
Published: July 2004

Hybrid density functional theory (HDFT) and post Hartree–Fock CCSD(T) methods are applied to elucidate the binding energies and the optimized MO distances of transition metal oxides: MO (M = Cr, Mn, Fe, Co, Ni, Cu). The HDFT method can reproduce the CCSD(T) results, in agreement with the experimental ones. The nature of the manganese–oxygen bonds in the Mn(VI)O, Mn(IV)O porphyrin (PP), and Mn(V)O PP systems are examined in relation to possible mechanisms of oxygen evolution from H2O2 and H2O in native and non‐native manganese complexes. It is found that the radical character of the high‐valent (PP)Mn(V)O bond is remarkable, showing the strong potential to generate molecular oxygen because of its high reactivity. The electronic structure and magnetic property of μ‐oxo‐bridged manganese porphyrin dimer (PPMn(III)OMn(III)PP) are investigated for further discussion of structure and reactivity of PPMn(X)O (X = II–IV). The potential curve for release of molecular oxygen from PPMn(II)O2 is also examined to show weak affinity of O2 in the Mn complex where the oxidation number (X) of Mn is low. Implications of the computational results are also discussed in relation to oxygen evolution reactions. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Conformational studies of benzyl alcohol and benzyl fluoride
Authors: Utzat Karissa , Restrepo Albeiro A. , Bohn Robert K. , Michels H. Harvey
Published: July 2004

The conformations of several benzyl compounds, C6H5CH2X, have been characterized by rotational spectra and theoretical structure calculations. We have observed the microwave spectrum of benzyl alcohol and its OD isotopomer at high resolution in a pulsed‐jet Fourier transform microwave spectrometer. The spectrum is consistent with an asymmetric stable conformation characterized by a CCCO dihedral angle of approximately 60°. The spectrum is strongly perturbed by tunneling interactions. The transitions are split into doublets consistent with tunneling interactions between two equivalent conformational minima. The observed splittings diminish upon deuterium substitution. These observations are similar to those previously reported by us for benzyl fluoride. However, the minimum energy conformation for benzyl fluoride has the CCF plane orthogonal to the plane of the phenyl ring. This conformation for benzyl fluoride is consistent with a model that minimizes steric repulsion between the fluorine of the CH2F group and the closest hydrogens located on the phenyl ring. For benzyl alcohol, previous studies have suggested a weak attraction between the π electrons of the phenyl ring and the substituent OH group as the explanation for the observed stable conformation. A theoretical analysis of the atomic charges in benzyl alcohol suggests another possible explanation of the observed structure. Atomic charges generated by fits to the electrostatic potential indicate a relatively strong dipole–dipole coupling between the CH group in the methylene side chain and the closest CH group in the phenyl ring. This results in a nearly planar orientation of the CH group in the methylene side chain with the phenyl ring, a conformation that yields the observed CCCO dihedral angle. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Fulleride superconductivity compared and contrasted with RVB theory of high Tc cuprates
Authors: Squire Richard H. , March Norman H.
Published: July 2004

Recently we proposed a microscopic mechanism for alkali‐metal doped Fulleride superconductivity. The aim of the current study is to compare and contrast such Fulleride superconductivity with that of high Tc cuprates. We focused earlier on “topological” superconductivity in the Fulleride case and so it seemed natural to make contact with the resonating valence bond treatment of Anderson et al. for the high Tc cuprates. Finally, some experimental points of contact involve the product of electrical resistivity and nuclear spin lattice relaxation times in the normal state of both classes of superconductors considered here. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Planck–Benzinger thermal work function in biological systems
Authors: Chun Paul W.
Published: July 2004

The Planck–Benzinger methodology provides a means of determining the innate temperature‐invariant enthalpy and thermal agitation energy, or the heat capacity integrals, ∫ ΔCp°(T)dT, and allows precise determination of 〈TCp〉, 〈Th〉, 〈Ts〉, and 〈Tm〉. It is a method for evaluating [ΔH − ΔH°(T0)], the heat of reaction for biological molecules at room temperature. The results imply that the negative Gibbs free energy change minimum at a well‐defined stable temperature, 〈Ts〉, where the bound unavailable energy TΔS° = 0, has its origin in the sequence‐specific hydrophobic interactions. Each case confirms the existence of a thermodynamic molecular switch wherein a change of sign in ΔCp°(T)reaction leads to true negative minimum in the Gibbs free energy change of reaction and, hence, a maximum in the related equilibrium constant, Keq. At this temperature, 〈TS〉, ΔH°(TS)(−) = ΔG°(TS)(−)min, the maximum work can be accomplished in biological systems. Application of the Planck–Benzinger methodology to biological systems has demonstrated a basic rule for life processes, in that there is a lower cutoff point, 〈Th〉, where entropy is favorable but enthalpy is unfavorable, that is, ΔH°(Th)(+) = TΔS°(Th)(+), and an upper cutoff, 〈Tm〉, above which enthalpy is favorable but entropy unfavorable, that is, ΔH°(Tm)(−) = TΔS°(Tm)(−). Only between these two limits, that is, where ΔG°(T) = 0, is the net chemical driving force favorable for such biological processes as protein folding; protein–protein, protein–nucleic acid or protein‐membrane interactions; and protein–self‐assembly. Indeed, all interacting biological systems examined using the Planck–Benzinger methodology have shown such a thermodynamic switch at the molecular level, suggesting that its existence may be universal. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Fast determination of the total free resveratrol content in wine by direct‐exposure‐probe, positive‐ion chemical ionization and collision‐induced‐dissociation mass spectrometry
Authors: Flamini Riccardo , Vedova Antonio Dalla
Published: July 2004

In the present work, a fast method has been developed for the determination of total free resveratrol in wine extracts by positive‐ion chemical ionization using methane as reagent gas and direct introduction of the sample into the mass spectrometer. Quantitative analysis is performed using 4′,5,7‐trihydroxyflavone as internal standard, by recording the product ions atm/z135 for resveratrol andm/z153 for the internal standard, both generated by collision‐induced dissociation experiments on the related [M+H]+ions. The method showed sufficient repeatability and satisfactory linearity in the range of concentration studied. Alternatively, because of the marked effect of matrices on the compounds released in the vaporization step, quantitative analysis was performed by addition of standard resveratrol to the sample, and the total free resveratrol content extrapolated from the calibration curve. Calibration curves for three different wine extracts had correlation coefficients between 0.91 and 0.99, and total free resveratrol contents between 11.8 and 17.2 mg/L were found. This method enabled us to determine the resveratrol‐potential of wine within a few minutes, thereby overcoming the time‐ and solvent‐consuming procedures needed for chromatographic methods. Copyright © 2004 John Wiley & Sons, Ltd.
Determination of linkage position and anomeric configuration in Hex‐Fuc disaccharides using electrospray ionization tandem mass spectrometry
Authors: Xue Jun , Song Liguo , Khaja Sirajud D. , Locke Robert D. , West Christopher M. , Laine Roger A. , Matta Khushi L.
Published: July 2004

Fixed‐energy sequential tandem mass spectrometry (MSn) capabilities offered by quadrupole ion trap instruments have been explored in a systematic study of six isomers of Gal‐Fucα‐OBenzyl disaccharides. Under collision‐induced dissociation (CID), sodiated molecular species generated in the positive‐ion electrospray ionization mode yield simple and predictable mass spectra. Information on interglycosidic linkages and configurations can be deduced from the relative intensities of the selected diagnostic fragments arising from the glycosidic bond cleavages and corroborated by the fragments arising from cross‐ring cleavages. As the CID patterns are not dependent on the number of prior tandem mass spectrometric steps, structures can be unambiguously assigned by matching the spectra with a library. The rules governing the fragmentation behavior of this class of oligosaccharides were tested for a representative isomeric disaccharide, Glcβ1,3Fucα‐OAllyl. The findings establish a basis for using MSn with a quadrupole ion trap instrument to elucidate structures of hexose‐fucose subunits from more complicated oligosaccharides. Energy‐resolved mass spectra were also acquired by CID tandem triple‐quadrupole mass spectrometry. The breakdown behavior of the molecular ions revealed patterns which could differentiate stereoisomers of Gal‐Fuc disaccharides over a range of collision energy from 20 to 50 eV. Copyright © 2004 John Wiley & Sons, Ltd.
Hamburger Sichel – Das neue Dach des Zentralen Omnibusbahnhofs
Authors: Keil Andreas , Werwigk Michael , Kempkes Marian
Published: July 2004

Weithin sichtbares Markenzeichen des neuen Zentralen Omnibus Bahnhofs (ZOB) Hamburg ist das signifikante Dach, das sich mit über 4000 m2 und einer Länge von knapp 200 m über die gesamte Anlage spannt. Die Anordnung der Bustaschen führte zu der sichelförmigen Geometrie des Daches, das wie ein überdimensionaler Bumerang über dem Busbahnhof mit seinen Betriebsgebäuden schwebt.

Das Dach steht einseitig auf einer Kolonnade schlanker Stützen, die dem Bogen der in 12 m Höhe liegenden, gekrümmten Stahl‐Stabrippenschale folgt. Daran angeschlossen sind Kragträger unterschiedlicher Länge, unter denen die großflächige Glaseindeckung punktförmig an Pfetten abgehängt ist.

Dieser Beitrag beschreibt den Entwurf, die Konstruktion und ausgewählte Besonderheiten bei Herstellung und Montage.
Der neue Flughafen in Bankok – eine ingenieurtechnische Herausforderung
Authors: Sobek Werner , Linder Josef , Krampen Jürgen
Published: July 2004

Der neue Flughafen in Bangkok ist z. Z. eine der größten Baustellen der Welt. Planung und Ausführung dieses Projektes erforderten von Planern und beteiligten Firmen extreme Sorgfalt und eine äußerst intensive Zusammenarbeit in allen Phasen des Projekts. Im nachfolgenden Artikel soll zunächst ein Überblick über die Gesamtmaßnahme gegeben werden, bevor dann am Beispiel der über 3100 m langen ‘Concoursen’ die vorbildliche Zusammenarbeit von Planern und ausführenden Firmen erläutert wird.
Berechnung von Stahlverbundträgern – Ein Rechenmodell zur Berücksichtigung von verformbaren, teiltragfähigen Verbundanschlüssen
Authors: Jost Markus , Odenbreit Christoph
Published: July 2004

Typische Verbundanschlüsse, wie z. B. in Bild 1 dargestellt, haben oft nicht die volle Tragfähigkeit des angeschlossenen Verbundträgers und sind auch zu biegeweich, um das volle Stützmoment, das sich aus der elastischen Berechnung unter der Annahme einer vollen Einspannung ergibt, aufbauen zu können. Andererseits sind aber die Steifigkeiten und die Tragfähigkeiten in den Anschlüssen zu groß, um sie einfach zu vernachlässigen. Im folgenden Artikel wird eine Methode vorgestellt, um die rechnerischen Kennwerte von Verbundanschlüssen zu ermitteln, das Verhalten des Anschlusses als bilineare Feder abzubilden und die Gesamtberechnung des Verbundträgers durchzuführen.
Trag‐ und Ermüdungsverhalten liegender Kopfbolzendübel unter Quer‐ und Längsschub
Authors: Kürschner Kai , Kuhlmann Ulrike
Published: July 2004

Neue interessante Verbundquerschnitte aus Stahlbeton und Baustahl im Hoch‐ und Brückenbau führen unter Berücksichtigung konstruktiver, fertigungstechnischer und wirtschaftlicher Gesichtspunkte zu einer liegenden, d.h. randnahen Anordnung von Kopfbolzendübeln. Infolge des geringen Abstands der Dübelreihe zum freien Plattenrand ergeben sich gegenüber stehenden bzw. randfernen Kopfbolzen unterschiedliche Bettungseigenschaften der Dübel im umgebenden Stahlbeton und somit auch ein abweichendes Trag‐ und Ermüdungsverhalten der Verbundfuge. Im Hinblick auf zukünftige Anwendungen von liegenden Kopfbolzendübeln werden auf Grundlage experimenteller und theoretischer Untersuchungen einfache Bemessungs‐ und Konstruktionsregeln für den Nachweis der Verbundfuge unter ruhendem Querschub, ruhendem Quer‐ und Längsschub und nicht ruhendem Längsschub vorgestellt.
Zur Toleranzklassifizierung im Stahlbau
Authors: Urbańska‐Galewska Elżbieta
Published: July 2004

In den letzten Jahrzehnten gab es wesentliche Veränderungen beim Bau von Stahlkonstruktionen. Die Genauigkeit bei der Herstellung und Montage wurde von mehreren europäischen und nationalen Normen bestimmt. Diese stimmen jedoch oft nicht überein und führen nicht immer zur richtigen Montage. Im Beitrag werden die Fragen der Imperfektion und der Toleranz in den aktuellen Normen besprochen und die Idee der Einführung von Genauigkeitsklassen für die Ausführung von Stahlkonstruktionen, in Abhängigkeit von mehreren projekttechnischen und wirtschaftlichen Faktoren, dargestellt. Zu diesem Zweck wird eine neue Klassifizierung der zulässigen Fertigungsabweichungen vorgeschlagen. Sie ist abhängig vom Ort des Auftretens und der Wertigkeit innerhalb der Montage. Dargestellt wird die Bestimmungsart der Fertigungsgenauigkeit von Koordinationsmontagemaßen mit Hilfe der Toleranzanalyse und ‐synthese, wobei die Methoden der Toleranzanalyse beschrieben werden. Die vorgeschlagene Methode der Toleranzklassifizierung ist ein modernes Werkzeug für die notwendige Qualitätssicherung von Stahlkonstruktionen ohne Zusatzkosten. Ein Zahlenbeispiel verdeutlicht die Methoden der Toleranzanalyse und ‐synthese.