bluuebunny/crossref_metadata_2025 huggingface dataset:
Linkage genome scan for loci predisposing to panic disorder or agoraphobia
Authors: Gelernter Joel , Bonvicini Kathleen , Page Grier , Woods Scott W. , Goddard Andrew W. , Kruger Susan , Pauls David L. , Goodson Susan
Published: August 2002

We conducted a 10 cM linkage genome scan in a set of 20 American pedigrees (153 subjects), ascertained through probands with panic disorder (PD). Several anxiety disorders segregate in these families; they were diagnosed on the basis of Schedule for Affective Disorders and Schizophrenia interview. In this article, we describe results for panic disorder and agoraphobia, which are closely related, common, heritable anxiety disorders. This is the first complete linkage genome scan for agoraphobia and the third for PD. A total of 407 markers (389 autosomal, 18 X chromosome) were genotyped. Multipoint LOD score and NPL analysis were completed using GENEHUNTER2. For PD, two genomic regions meet criteria for suggestive linkage. One of these regions is on chromosome 1 (LOD score = 2.04). This region coincides with a region that generated a LOD score of 1.1 in a previous genome scan by Crowe et al. [2001: Am J Med Genet (Neuropsychiatr Genet) 105:105–109]. The other (LOD score = 2.01) is located on chromosome 11p and occurs at marker CCKBR, one of eight candidate genes examined. For agoraphobia, the most promising potential linkage was on chromosome 3 (NPL score = 2.75; P = 0.005). This was accounted for primarily by a single family that by itself generated an NPL score of 10.01 (P = 0.0039) and a LOD score of 2.10. These results provide initial evidence for a genetic locus on chromosome 3 that contributes to risk for agoraphobia. They also support suggestive linkage to two risk loci for panic disorder. Additional potential loci were identified with lesser statistical support; several of these were consistent with previously reported panic disorder linkage results. Overall, the results presented here suggest that PD and agoraphobia are complex traits that share some, but not all, of their susceptibility loci. Published 2001 Wiley‐Liss, Inc.
Genetic relationship of Chinese ethnic populations revealed by mtDNA sequence diversity
Authors: Yao Yong‐Gang , Nie Long , Harpending Henry , Fu Yun‐Xin , Yuan Zhi‐Gang , Zhang Ya‐Ping
Published: August 2002

The origin and demographic history of the ethnic populations of China have not been clearly resolved. In this study, we examined the hypervariable segment I sequences (HVSI) of the mitochondrial DNA control region in 372 individuals from nine Chinese populations and one northern Thai population. A relatively high percentage of individuals was found to share sequences with those from other populations of the same ethnogenesis. In general, the populations of southern or Pai‐Yuei tribal origin showed high haplotype diversity and nucleotide diversity compared with the populations of northern or Di‐Qiang tribal origin. Mismatch distributions from these populations showed concordant features. All except the northern groups Nu, Lisu, Tibetan, and Mongolian showed typical signatures of ancient population expansions in the mismatch distributions and neutrality tests. Episodes of extreme size reduction in the past are one of the likely explanations for the absence of evidence of expansion in northern populations. Small sample sizes as well as samples from isolated subpopulations contributed to the bumpy mismatch distributions observed. Phylogenetic analysis and haplotype sharing among populations suggest that current mtDNA variation in these ethnic populations could reveal their ethnohistory to some extent, but in general, linguistic and geographic classifications of the populations did not agree well with classification by mtDNA variation. Am J Phys Anthropol 118:63–76, 2002. © 2002 Wiley‐Liss, Inc.
Integration, phylogeny, and the hominid cranial base
Authors: Strait David S.
Published: August 2002

Basicranial features were examined in catarrhine primates and early hominids in order to demonstrate how information about morphological integration can be incorporated into phylogenetic analysis. Hypotheses purporting to explain the functional and structural relationships of basicranial characters were tested using factor analysis. Characters found to be functionally or structurally related to each other were then further examined in order to determine whether there was evidence that they were phylogenetically independent. If phylogenetic independence could not be demonstrated, then the characters were presumed to be integrated and were grouped into a complex. That complex was then treated as if it were a single character for the purposes of cladistic analysis.

Factor analysis revealed that five basicranial features may be structurally related to relative brain size in hominoids. Depending on how one defines phylogenetic independence, as few as two, or as many as all of those characters might be morphologically integrated. A cladistic analysis of early hominids based on basicranial features revealed that the use of integrated complexes had a substantial effect on the phylogenetic position of Australopithecus africanus, a species whose relationships are poorly resolved. Moreover, the use of complexes also had an effect on reanalyses of certain published cladistic data sets, implying that those studies might have been biased by patterns of basicranial integration. These results demonstrate that patterns of morphological integration need to be considered carefully in all morphology‐based cladistic analyses, regardless of taxon or anatomical focus. However, an important caveat is that the functional and structural hypotheses tested here predicted much higher degrees of integration than were observed. This result warns strongly that hypotheses of integration must be tested before they can be adequately employed in phylogenetic analysis. The uncritical acceptance of an untested hypothesis of integration is likely to be as disruptive to a cladistic analysis as when integration is ignored. Am J Phys Anthropol 114:273–297, 2001. © 2001 Wiley‐Liss, Inc.
Geographic variation in tool use on Neesia fruits in orangutans
Authors: Van Schaik Carel P. , Knott Cheryl D.
Published: August 2002

Geographic variation in the presence of skilled behavior may reflect geographic variation in genetic predispositions or ecological conditions (accompanied by reliable expression during development), or it may reflect the vagaries of invention and the appropriate social conditions for persistence. In this study, we compare the feeding techniques and tool‐using skills used by orangutans to extract the nutritious seeds from Neesia fruits between Suaq Balimbing on Sumatra and Gunung Palung on Borneo, and map the distribution of Neesia tool use in Sumatran swamps. We show that neither genetics nor ecology is sufficient to explain the distribution of this tool use, confirming earlier findings on chimpanzees. We conclude that the ability to learn to use tools determines the geographic distribution. It is impossible to distinguish between the history of invention and the conditions for social transmission as the causal factors, but the high density and the social tolerance at Suaq Balimbing create propitious conditions for the maintenance of the skill as a tradition once it has been invented. High orangutan densities in the other Sumatran coastal swamps with Neesia tool use support the conclusion that suitable transmission conditions are the critical factor to explain the geographic distribution of skills such as feeding tool use. Am J Phys Anthropol 114:331–342, 2001. © 2001 Wiley‐Liss, Inc.
Reorganization of somatic sensory function in the human thalamus after stroke
Authors: Ohara Shinji , Lenz Frederick A.
Published: August 2002

A patient with a thalamic stroke underwent a microelectrode‐guided stereotactic thalamic exploration during surgery for control of tremor. The results of somatic sensory mapping in this patient were compared with explorations carried out during stereotactic surgery for the control of essential tremor (70 patients). There was evidence both of somatotopic reorganization and of anatomic reorganization of the representation of deep structures in the principal somatic sensory nucleus of the thalamus and the nuclei located anterior to it. This case demonstrates that thalamic reorganization can occur after a thalamic stroke and may play a role in recovery from such a stroke.
Metabolites of arsenobetaine in rats: does decomposition of arsenobetaine occur in mammals?
Authors: Yoshida Kaoru , Kuroda Koichi , Inoue Yoshinori , Chen Hua , Wanibuchi Hideki , Fukushima Shoji , Endo Ginji
Published: August 2002

Biotransformation following oral administration of arsenobetaine (AsBe), the major arsenic compound in marine animals, was studied in rats. Male F344/DuCrj rats were administered a single dose of AsBe (20 mg As kg−1) orally. Urine was collected at 0, 2, 4, 6, 8, 10, 12, 24, 48, 72, and 96 h after administration by forced urination. Arsenic metabolites in urine were analyzed by ion chromatography with inductively coupled plasma mass spectrometry. Urinary elimination of AsBe, trimethylarsine oxide (TMAO), dimethylarsinic acid (DMA), methylarsonic acid (MMA), tetramethylarsonium (TeMA), an unidentified arsenic metabolite, arsenate, and arsenite was determined at various time points after administration. Unmetabolized AsBe was the most common form. Most elimination of unchanged AsBe occurred within 48 h, with peak elimination between 0 and 2 h. A small portion of administered AsBe was eliminated as TMAO and TeMA, with peak elimination between 0 and 2 h. Elimination of the unidentified metabolite, MMA, DMA, and inorganic arsenic occurred later and to a slight extent. A delay in elimination of the unidentified compound, MMA, DMA, and inorganic arsenic compared with that of TMAO suggests that the former compounds may be formed from TMAO. Degradation of AsBe by an intestinal bacterium, Escherichia coli, did not occur in rats. These results suggest that TMAO may be formed from AsBe, and that TMAO may subsequently be converted to the unidentified compound and demethylated arsenic compounds. Copyright ­© 2001 John Wiley & Sons, Ltd.
High‐density polyethylene/carbon black conductive composites. II. Effect of electron beam irradiation on relationship between resistivity–temperature behavior and volume expansion
Authors: Zhang Jian‐Feng , Zheng Qiang , Yang Yi‐Quan , Yi Xiao‐Su
Published: August 2002

A study on the contribution of thermal volume expansion to electrical properties is carried out for high‐density polyethylene (HDPE)/carbon black (CB) composites irradiated by an electron beam. The results show that the volume expansion obviously generates the positive temperature coefficient (PTC) characteristic of resistivity for unirradiated HDPE/CB composites, but the contribution of volume expansion is decreased for crosslinked HDPE in the composites by electron beam irradiation. A higher degree of crosslinking produced by irradiation in the molten state limits the movability of HDPE chains and CB particles so effectively that it decreases the PTC intensity, which is compared with that irradiated at room temperature. It is suggested that the differences in the resistivity–temperature behavior are not explained satisfactorily on only the basis of the thermal volume expansion, and the decreased movability of HDPE chains and CB particles are believed to be the most fatal factors in lowering the PTC effect. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 3117–3122, 2002; DOI 10.1002/app.10050
Drug‐releasing behavior of MPEG/PLA block copolymer micelles and solid particles controlled by component block length
Authors: Kyu Sung , Dukjoon Choi , Kim
Published: August 2002

Three series of poly(ethylene glycol)methyl ether (MPEG)/poly(lactic acid) (PLA) block copolymer systems, composed of MPEG in the molecular weights of 2000, 5000, and 750 g/gmol, respectively, and PLA in different molecular weights were synthesized. The chemical structure and physical properties were investigated using FTIR, NMR, DSC, TGA, and GPC. Different crystallization and melting transition behavior were observed according to the variation of the component block length. Either nano‐sized micelles or solid particles were formed in water, depending on the component block length and its ratio. The mean diameter of spherical drug carriers was controlled by the preparation conditions and was characterized using DLS and SEM. Indomethacin was loaded into nano‐sized spherical polymer carriers. The releasing rates were significantly affected by not only the sizes but also by the physical state of the drug carriers in the media, resulting from the difference in the component block length and the molecular entanglement of the PLA cores. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 435–445, 2002
Use of rice husk ash as filler in natural rubber vulcanizates: In comparison with other commercial fillers
Authors: Sae‐Oui P. , Rakdee C. , Thanmathorn P.
Published: August 2002

Rice husk ash is mainly composed of silica and carbon black remaining from incomplete combustion. Both silica and carbon black have long been recognized as the main reinforcing fillers used in the rubber industry to enhance certain properties of rubber vulcanizates, such as modulus and tensile strength. In this study, two grades of rice husk ash (low‐ and high‐carbon contents) were used as filler in natural rubber. Comparison was made of the reinforcing effect between rice husk ashes and other commercial fillers such as talcum, china clay, calcium carbonate, silica, and carbon black. Fourier transform infrared spectroscopy (FTIR) analysis was employed to study the presence of functional groups on the ash surface. The effect of silane coupling agent, bis(3‐triethoxysilylpropyl)tetrasulfane (Si‐69), on the properties of ash‐filled vulcanizates was also investigated. It was found that both grades of rice husk ash provide inferior mechanical properties (tensile strength, modulus, hardness, abrasion resistance, and tear strength) in comparison with reinforcing fillers such as silica and carbon black. However, the mechanical properties of the vulcanizates filled with rice husk ash are comparable to those filled with inert fillers. The addition of silane‐coupling agent has little effect on the properties of the ash‐filled vulcanizates. This is simply due to the lack of silanol groups on the ash surface. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2485–2493, 2002
Effect of degumming on the tensile properties of silkworm (Bombyx mori) silk fiber
Authors: Pérez‐Rigueiro J. , Elices M. , Llorca J. , Viney C.
Published: August 2002

Forcibly reeled silkworm (Bombyx mori) silk was used to study how exposure to a degumming treatment (boiling in distilled water for 30 min) affects tensile properties. Because forcibly reeled and naturally spun fibers exhibit comparable mechanical behavior, the results can be generalized to material obtained conventionally from cocoons. The effects of degumming include: a decrease in the initial elastic modulus, a decrease in the stress at the proportional limit (yield strength), a change in the qualitative shape of force‐displacement curves, and significant qualitative and quantitative variability in force‐displacement data from samples subjected to nominally identical degumming histories. Immersion in water at room temperature or heating in air at 100°C for 30 min are both qualitatively equivalent to a 30‐min degumming treatment in boiling water, in terms of the effect on silk tensile properties. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1431–1437, 2002; DOI 10.1002/app.10366
Synthesis and evaluation of sucrose‐containing polymeric hydrogels for oral drug delivery
Authors: Shantha K. L. , Harding D. R. K.
Published: August 2002

Biodegradable and biocompatible copolymeric hydrogels based on sucrose acrylate, N‐vinyl‐2‐pyrrolidinone, and acrylic acid were designed and synthesized. Because of the growing importance of sugar‐based hydrogels as drug delivery systems, these new pH‐responsive sucrose‐containing copolymeric hydrogels were investigated for oral drug delivery. The sucrose acrylate monomer was synthesized and characterized. The copolymeric hydrogel was synthesized by free‐radical polymerization. Azobisisobutyronitrile (AIBN) was the free‐radical initiator employed and bismethyleneacrylamide (BIS) was the crosslinking agent used for hydrogel preparations. Homopolymeric vinyl pyrrolidone hydrogels were also prepared by the same technique. The hydrogels were characterized by differential scanning calorimetry, thermogravimetric analysis, and scanning electron microscopy. Equilibrium swelling studies were carried out in enzyme‐free simulated gastric and intestinal fluids (SGF and SIF, respectively). These results indicate the pH‐responsive nature of the hydrogels. The gels swelled more in SIF than in SGF. A model drug, propranolol hydrochloride (PPH), was entrapped in these gels and the in vitro release profiles were established separately in both enzyme‐free SGF and enzyme‐free SIF. The drug release was found to be faster in SIF. About 93 and 99% of the entrapped drug was released over a period of 24 h in SGF and SIF, respectively. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2597–2604, 2002
Polyimide nanocomposite with a hexadecylamine clay: Synthesis and characterization
Authors: Chang Jin‐Hae , Park Dae‐Keun , Ihn Kyo Jin
Published: August 2002

A poly(amic acid) was prepared by the reaction of 3,3′‐dihydroxybenzidine and pyromellitic dianhydride in N,N‐dimethylacetamide. Hexadecylamine was used as an organophilic alkylamine in organoclay. Cast films were obtained from blend solutions of the precursor polymer and the organoclay. The cast film was heat treated at different temperatures to create polyimide (PI) hybrid films. We set out to clarify the intercalation of PI chains to hexadecylamine–montmorillonite (C16–MMT) and to improve thermal and tensile properties and the gas barrier. It was found that the addition of only a small amount of organoclay was enough to improve both the thermal and the mechanical properties of PIs. Maximum enhancement in the ultimate tensile strength for PI hybrids was observed for the blends containing 4% C16–MMT. The initial modulus monotonically increased with further increases in C16–MMT content. Water vapor permeability was decreased with increasing clay loading from 1 to 8 wt %. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2294–2301, 2002
Hemodialysis membrane prepared from cellulose/N‐methylmorpholine‐N‐oxide solution. I. Effect of membrane preparation conditions on its permeation characteristics
Authors: Abe Yoshihiko , Mochizuki Akira
Published: August 2002

Flat hemodialysis membranes were prepared from cellulose/N‐methylmorpholine‐N‐oxide (NMMO) solutions (dope) with different cellulose concentrations (6–8 wt %) by using a phase‐inversion method. The coagulant used was NMMO aqueous solution, of which the NMMO concentration and its temperature were varied in the range of 0 to 50 wt % and 5 to 60°C, respectively. The effects of these preparation conditions on the permeation characteristics, the ultrafiltration rate (UFR) of pure water, and sieving coefficient (SC) of dextran, were investigated. The decrease in cellulose concentration of the dope and the increases in both temperature and NMMO concentration of the coagulant gave a membrane with high UFR. Concerning the SC, the increase of the cellulose concentration and the decreases in both temperature and NMMO concentration gave a good result. Consequently, the membrane having the preferable UFR and SC as a hemodialysis membrane was obtained when the 8 wt % cellulose dope was coagulated in water at 5°C. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2302–2307, 2002
Conduction mechanism in H‐type polysiloxane‐polypyrrole block copolymers
Authors: Bozkurt A. , Parlak M. , Erçelebi Ç. , Toppare L.
Published: August 2002

Conducting polymers of polysiloxane‐polypyrrole were synthesized by electropolymerization of the pyrrole monomer through pyrrole moieties in N‐pyrrole‐terminated polysiloxanes. Sodium paratoluene sulfonate was used as the electrolyte. Scanning electron microscopy (SEM) was used to determine the surface morphology of the films. The room‐temperature conductivity values of the films were found to be in the range of 1.9–4.4 × 10−4 (Ω cm)−1, depending on the supporting electrolyte concentration. The temperature dependence of the dc conductivities of the copolymers having different dopant concentrations was investigated within the temperature range of 100–320 K. The evaluated parameters showed that the electrical transport is dominated by variable range hopping. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 52–56, 2002
Simultaneous determination of molecular weight and crystallinity of recycled HDPE by infrared spectroscopy and multivariate calibration
Authors: Camacho Walker , Karlsson Sigbritt
Published: August 2002

An attempt of correlating molecular weight (Mn) of recycled high‐density polyethylene (HDPE) as measured by size‐exclusion chromatography (SEC) with diffuse reflectance near and mid‐infrared spectroscopy (NIR/MIR) was made by means of multivariate calibration. The spectral data obtained was also used to extract information about the degree of crystallinity of the recycled resin. Differential scanning calorimetry (DSC) was used as the reference method. Partial least‐squares (PLS) calibration was performed on the MIR and NIR spectral data for prediction of Mn. Four PC factors described fully the PLS models. The root‐mean‐square error of prediction (RMSEP) obtained with MIR data was 360, whereas a RMSEP of 470 was achieved when calibration was carried out on the diffuse reflectance NIR data. A PLS calibration for prediction of degree of crystallinity was performed on the NIR data in the 1100–1900‐nm region, but the ability of prediction of this model was poor. However a PLS calibration in the region 2000–2500 nm yield better results. Four PC factors explained the most of the variance in the spectra and the RMSEP was 0.4 wt %. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 321–327, 2002
Grafting of selected presynthesized macromonomers onto various dispersions of silica particles
Authors: Sartore Luciana , Penco Maurizio , Bignotti Fabio , Peroni Isabella , Gil Maria Helena , Ramos M. Andrade , D'Amore Alberto
Published: August 2002

A new process was developed which enables one to obtain surface‐modified silica with a high heavy metal ion complexing ability. The synthetic approach is based on grafting of vinyl‐terminated macromonomers onto silica via covalent bonding. A proper selection of the macromonomer structure, molecular weight, and molecular weight distribution allows materials to be obtained with a range of desirable properties. The process has been tested on various dispersions (ranging from 35 and 200 μm) of silica particles and two structurally related macromonomers. Native silica and the resulting mixed organic–inorganic products were fully characterized by IR spectroscopy, SEM, yield of grafting (elemental analysis and calcination), density (helium pycnometry), specific surface area (BET method), and pore size (gas adsorption and mercury porosimetry) measurements. It was found that the corresponding polymers are effectively grafted onto the surface; the density, surface area, and pore size of the silica particles decrease with polymer grafting. Preliminary results on metal‐ion uptake indicate that polymer‐grafted silica exhibits an excellent complexing ability. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1287–1296, 2002
Synthesis of polyetherols from melamine and ethylene carbonate
Authors: Kucharski Mieczysław , Kijowska Dorota
Published: August 2002

Attempts to synthesize s‐triazine ring containing polyetherols from melamine and ethylene carbonate are described. The conditions of synthesis providing optimal yields of the polyetherols were 165°C, melamine to ethylene carbonate molar ratio 1 : 9 to 1 : 18, and 4 g of potassium carbonate or diazabicyclo[2.2.2]octane catalyst per mole of melamine. The structure of the products was established by 1H‐NMR and IR spectroscopy. The kind and amount of side products [mostly poly(ethylene glycols)] was determined by GLC. The polyetherols have been found useful in the synthesis of polyurethanes of improved thermal stability. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1776–1784, 2001
Erasure below glass‐transition temperature of effect of isothermal physical aging in fully cured epoxy/amine thermosetting system
Authors: Lee Jong Keun , Hwang Jae Young , Gillham J. K.
Published: August 2002

The erasure below the glass‐transition temperature (Tg) of the effect of isothermal physical aging (at aging temperature Ta) in a fully cured epoxy/amine thermosetting system is investigated using the torsional braid analysis (TBA) dynamic mechanical analysis technique and the differential scanning calorimetry (DSC) technique. From the TBA temperature scans, the intensity of the localized perturbation of the moduli in the vicinity of the Ta (90°C), due to isothermal physical aging, is decreased by heating to below the Tg (Tg∞ = 177°C), indicating that the physical aging effect can be eliminated by heating to below the Tg. The isothermal aging effect in the vicinity of the Ta is almost completely eliminated by heating to 50°C above the Ta (i.e., 140°C); however, a competing aging effect occurs above Ta at higher temperatures during the heating. Erasure below Tg of the isothermal physical aging effect is inferred from DSC experiments from the diminished relaxation enthalpy in the vicinity of the Tg, which is measured from the difference in areas between the aged (Ta = 150°C) and deaged thermograms. A comparison of the TBA and DSC results is made. Implications on the heterogeneous nature of the amorphous glassy state of polymers are discussed. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 396–404, 2001
Separation and extraction of some heavy and toxic metal ions from their wastes by grafted membranes
Authors: Hegazy El‐Sayed A. , Kamal H. , Khalifa N. A. , Mahmoud Gh. A.
Published: August 2002

Preparation and characterization of a series of ion‐exchange membranes for the purpose of separation and extraction of some heavy and toxic metal ions from their wastes were studied. Such ion‐exchange membranes were prepared by γ‐radiation grafting of acrylonitrile (AN) and vinyl acetate (VAc) in a binary monomer mixture onto low‐density polyethylene (LDPE) using the direct technique of grafting. The reaction conditions at which the grafting process proceeds successfully were determined. Many modification treatments were attempted for the prepared membranes to improve their ion‐exchange properties. The possibility of their practical use in waste‐water treatment to remove some heavy and toxic metal ions such as Pb2+, Cd 2+, Cu2+, Fe3+, Sr2+, and Li+ were investigated. These grafted membranes showed great promise for possible use in the field of extraction and removal of some heavy and toxic metals from their wastes. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 849–860, 2001
Generalization of polymer/organic solvent interaction processes by means of linear polyparameter equations. I. Swelling of polyethylene
Authors: Makitra R. , Pyrih Y. , Sagladko E. , Turovskiy A. , Zaikov G.
Published: August 2002

A solvent's molar volume is the factor that determines its ability to penetrate into a polymer structure. However, the available data for polyethylene swelling in organic solvents may be quantitatively linked with their physicochemical properties only by use of polyparameter equations, which take into account not only the molar volume of solvents but also their ability for specific and nonspecific solvation. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3133–3140, 2001
Strain‐induced crystallization in uniaxially drawn PETG plates
Authors: Kattan M. , Dargent E. , Ledru J. , Grenet J.
Published: August 2002

The copolyester poly(ethylene glycol‐co‐cyclohexane‐1,4‐dimethanol terephthalate) (PETG) is used industrially as an uncrystallizable polymer, whereas PET is an inherently crystallizable polymer. Nevertheless, a crystalline phase could appear in the material. To create a strain‐induced crystalline phase in an initially amorphous PETG material, plates were placed in the heating chamber of a tensile machine at 100°C and uniaxially drawn to obtain different samples with various draw ratios. During DSC analysis of highly drawn samples, perturbations of the baseline appear above the glass‐transition temperature, consisting of weak exothermic and endothermic phenomena. Comparison of DSC and X‐ray diffraction analysis of drawn PETG and PET shows that a strain‐induced crystalline phase appears in this copolyester. A spherulitic superstructure could also appear after lengthy annealing. Analysis of this semicrystalline material allowed estimation of the degree of crystallinity, about 3% after a drawing at high draw ratio and about 11% for undrawn annealed material. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3405–3412, 2001
Soluble polypyrrole copolymers
Authors: Ustamehmetoğlu Belkis , Kizilcan Nilgün , Saraç A. Sezai , Akar Ahmet
Published: August 2002

A new class of dimethyl formamide (DMF)– and acetone‐soluble conducting pyrrole–ketonic resin copolymers has been developed. This was accomplished by oxidatively polymerizing pyrrole monomer by Ce(IV) salt in the presence of methyl ethyl ketone formaldehyde resin (MEKF–R). The resulting copolymers were readily dissolved in DMF and acetone. These products were characterized by FTIR and UV‐visible spectroscopy, conductivity, four‐probe conductivity, viscosity, and DSC measurements. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1098–1106, 2001
Preparation and characterization of organosoluble polyimides based on 1,1‐bis[4‐(3,4‐aminophenoxy)phenyl]cyclohexane and commercial aromatic dianhydrides
Authors: Yang Chin‐Ping , Chen Ruei‐Shin , Yu Chien‐Wen
Published: August 2002

A bis(ether amine) III‐A containing a cyclohexane cardo group, 1,1‐bis[4‐(4‐aminophenoxy)phenyl]cyclohexane, was synthesized and used as a monomer to prepare polyimides VI‐A with six commercial dianhydrides via three different procedures. The intermediate poly(amic acid)s had inherent viscosities of 0.83–1.69 dL g−1 and were thermally or chemically converted into polyimides. Polyimides were also prepared by high‐temperature direct polymerization in m‐cresol and had inherent viscosities higher than the thermally or chemically cyclodehydrated ones. To improve the solubility of polyimides, six copolyimides were also synthesized from bis(ether amine) III‐A with a pair of dianhydrides, which contained 3,3′,4,4′‐diphenylsulfonetetracarboxylic dianhydride or 4,4′‐hexafluoroisopropylidenediphthalic anhydride. Series VI‐A polyimides were characterized by the good physical properties of their film‐forming ability, thermal stability, and tensile properties. A comparative study of the properties, with the corresponding polyimides derived from 2,2‐bis[4‐(4‐aminophenoxy)phenyl]propane, is also presented. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2750–2759, 2001
Effects of the carboxyl concentration on the solid‐state polymerization of poly(ethylene terephthalate)
Authors: Duh Ben
Published: August 2002

There are two types of polycondensation reactions in the solid‐state polymerization (SSP) of poly(ethylene terephthalate) (PET), namely, transesterification and esterification. Transesterification is the reaction between two hydroxyl ends with ethylene glycol as the byproduct, and esterification is the reaction between a carboxyl end and a hydroxyl end with water as the byproduct. The SSP of powdered PET in a fluid bed is practically a reaction‐controlled process because of negligible or very small diffusion resistance. It can be proved mathematically that an optimal carboxyl concentration for reaction‐controlled SSP exists only if k2/k1 > 2, where k2 and k1 are the forward reaction rate constants of esterification and transesterification, respectively. Several interesting observations were made in fluid‐bed SSP experiments of powdered PET: (1) the SSP rate increases monotonously with decreasing carboxyl concentration, (2) k2 < k1 in the presence of sufficient catalyst, (3) k1 decreases with increasing carboxyl concentration if the catalyst concentration is insufficient, and (4) the minimum catalyst concentration required to achieve the highest SSP rate decreases with decreasing carboxyl concentration. In the SSP of pelletized PET, both reaction and diffusion are important, and there exists an optimal carboxyl concentration for the fastest SSP rate because esterification, which generates the faster diffusing byproduct, is retarded less than transesterification in the presence of substantial diffusion resistance. The optimal prepolymer carboxyl concentration, which ranges from 25 to 40% of the total end‐group concentration in most commercial SSP processes, increases with increasing pellet size and product molecular weight. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1288–1304, 2002
Constructed shallow zones along navigation canals: vegetation establishment and change in relation to environmental characteristics
Authors: Boedeltje Ger , Smolders Alfons J.P. , Roelofs Jan G.M. , Van Groenendael Jan M.
Published: August 2002

An Erratum has been published for this article in Aquatic Conservation: Marine and Freshwater Ecosystems 12(2), 2002, 251

In recent decades shallow zones have been constructed along navigation canals in the Netherlands which form a potential new habitat for aquatic macrophytes and helophytes absent from traditional canals.

The aim of this study was to examine the relationships between the aquatic plant vegetation that becomes established and the physical and chemical characteristics of water and sediment, in order to find the determinants of species composition and the changes therein. Data were collected in 1998 and 1999 from 80 plots in bank zones at varying stages of development since construction along two navigation canals.

Plots 3–5 years old were partly dominated by rooting submerged macrophytes such as Potamogeton pectinatus, Elodea nuttallii and Potamogeton pusillus; locally non‐rooting species occurred such as Ceratophyllum demersum, Lemna minor and Spirodela polyrhiza. Older plots contained Phragmites australis, locally mixed with free‐floating species. Hydrological isolation from the eutrophic canals was indicated by the presence of Chara vulgaris.

Characteristics of both water layer and sediment could explain the variation in vegetation composition. Rooting submerged macrophytes predominantly occurred in sites with a thin (<2 cm) layer of sediment with relatively low concentrations of organic matter; moreover, ammonium concentrations in the water layer and sediment pore water were relatively low. Stands of non‐rooting macrophytes and of Phragmites australis were characterized by a relatively thick sediment layer and high ammonium levels in the pore water. Light limitation in turbid water, associated with navigation and eutrophication, may also play a role.

Although submerged aquatic macrophytes persist for a relatively short time, shallow zones nevertheless function as a habitat for helophyte communities and contribute to a higher aquatic biodiversity than is associated with traditional banks along navigation canals.

Copyright © 2001 John Wiley & Sons, Ltd.
The Ferret's vomeronasal organ and accessory olfactory bulb: Effect of hormone manipulation in adult males and females
Authors: Kelliher Kevin R. , Baum Michael J. , Meredith Michael
Published: August 2002

The male ferret, a carnivore, was recently shown to possess a vomeronasal organ (VNO). We compared the morphology of the VNO and its associated accessory olfactory bulb (AOB) in male and female ferrets that were killed in adulthood. The volume and surface area of the VNO neuroepithelium were similar in adult gonadectomized male and female ferrets regardless of whether they were treated with testosterone propionate (TP) or oil vehicle. An AOB was localized bilaterally in the medial caudal part of the olfactory bulbs of adult ferrets using soybean agglutin binding and immunostaining for luteinizing hormone‐releasing hormone and tyrosine hydroxylase as well as Nissl staining of coronal, horizontal, and sagittal brain sections. There was no effect of sex or TP treatment on AOB cell layer volume in adult gonadectomized animals. We found the ferret's AOB to be more medially located and much smaller than previously reported in this species, thus highlighting the importance of using several histochemical markers to characterize this structure in any previously unexamined species. Adult male and female ferrets both have a VNO and an associated AOB. More research is needed to determine what role, if any, this accessory olfactory system plays in mediating behavioral and neuroendocrine responses to pheromones in ferrets of either sex. Anat Rec 263:280–288, 2001. © 2001 Wiley‐Liss, Inc.
Improved RP‐HPLC determination of quinine in plasma and whole blood stored on filter paper
Authors: Kolawole J.A. , Mustapha A.
Published: August 2002

Analysis of quinine in plasma and whole blood samples dried on filter paper is described. Sample preparation involves liquid extraction of plasma and whole blood from the filter paper and subsequent solid‐phase extraction using C8 Bond Elut cartridges. A reverse‐phase liquid chromatography system with UV detection and fluorescence detection was used. The analytical characteristics of the method are reported, with a quantification limit of 0.1 µg mL−1 and within an assay coefficient of variation of 5.6–8.4% in plasma and 6.5–12% in whole blood. Representative chromatograms are shown as a function of time for samples from human subjects after ingestion of a single 400‐mg dose of quinine sulphate. Quinidine, dihydroquinine and metabolites are well separated from quinine with a resolution of above 1 (Rs>1). Copyright © 2000 John Wiley & Sons, Ltd.
The mental accounting of sunk time costs: why time is not like money
Authors: Soman Dilip
Published: August 2002

The sunk‐cost effect, an irrational attention to non‐recoverable past costs while making current decisions, has been documented widely in the domain of monetary costs. In this paper, I study the effect of past time investments on current decisions. In three experiments using choice situations, I demonstrate that the sunk‐cost effect is not observed for past investments of time, but the effect reappears when the investments are expressed as monetary quantities. I further propose that this ‘pseudo‐rationality’ is due to the fact that individuals lack the ability to account for time in the same way as they account for money. In two additional experiments, I facilitate the accounting of time and show that the irrational sunk‐cost effect reappears. In a final experiment, I test my propositions in a setting where subjects make real investments of time and subsequently make real choices. Copyright © 2001 John Wiley & Sons, Ltd.
Diversity in the mechanisms of gene regulation by estrogen receptors
Authors: Sanchez Rocio , Nguyen Denis , Rocha Walter , White John H. , Mader Sylvie
Published: August 2002

The sequencing of the human genome has opened the way for using bioinformatics to identify sets of genes controlled by specific regulatory signals. Here, we review the unexpected diversity of DNA response elements mediating transcriptional regulation by estrogen receptors (ERs), which control the broad physiological effects of estrogens. Consensus palindromic estrogen response elements are found in only a few known estrogen target genes, whereas most responsive genes contain only low‐affinity half palindromes, which may also control regulation by other nuclear receptors. ERs can also regulate gene expression in the absence of direct interaction with DNA, via protein–protein interactions with other transcription factors or by modulating the activity of upstream signaling components, thereby significantly expanding the repertoire of estrogen‐responsive genes. These diverse mechanisms of action must be taken into account in screening for potential estrogen‐responsive sequences in the genome or in regulatory regions of target genes identified by expression profiling. BioEssays 24:244–254, 2002. © 2002 Wiley Periodicals, Inc.; DOI 10.1002/bies.10066
Polyps, peptides and patterning
Authors: Bosch Thomas C.G. , Fujisawa Toshitaka
Published: August 2002

Peptides serve as important signalling molecules in development and differentiation in the simple metazoan Hydra. A systematic approach (The Hydra Peptide Project) has revealed that Hydra contains several hundreds of peptide signalling molecules, some of which are neuropeptides and others emanate from epithelial cells. These peptides control biological processes as diverse as muscle contraction, neuron differentiation, and the positional value gradient. Signal peptides cause changes in cell behaviour by controlling target genes such as matrix metalloproteases. The abundance of peptides in Hydra raises the question of whether, in early metazoan evolution, cell–cell communication was based mainly on these small molecules rather than on the growth‐factor‐like cytokines that control differentiation and development in higher animals. BioEssays 23:420–427, 2001. © 2001 John Wiley & Sons, Inc.
Plectin repeats and modules: strategic cysteines and their presumed impact on cytolinker functions
Authors: Janda Lubomír , Damborský Jiří , Rezniczek Günther A. , Wiche Gerhard
Published: August 2002

Plectin, a member of the cytolinkers protein family, plays a crucial role in cells as a stabilizing element of cells against mechanical stress. Its absence results in muscular dystrophy, skin blistering, and signs of neuropathy. The C‐terminal domain of plectin contains several highly homologous repeat domains that also occur in other cytolinkers. Secondary structure analysis revealed that the building block of these domains, the PLEC repeat, is similar to the ankyrin repeat. We present a model that attempts to explain how the C‐terminal domain, which comprises ∼1900 amino acid, could be stabilized to maintain its structural integrity even under extensive mechanical stress. In this model, larger solenoid modules formed from PLEC repeats can be disulfide‐bridged via conserved cysteines. Our hypothesis suggests that this process could be mediated by cytoplasmic NOS‐generated products, such as the radical peroxynitrite. Reinforcement of molecular structure would provide a rationale why during exercising or physical stress radicals areformed without necessarily being deleterious. This article contains supplementary material that may be viewed at the BioEssays website at http://www.interscience.wiley.com/jpages/0265‐9247/suppmat/23/v23_11.1064.html. BioEssays 23:1064–1069, 2001. © 2001 John Wiley & Sons, Inc.
Effect of genetic background and culture conditions on the production of herpesvirus‐based gene therapy vectors
Authors: Ozuer Ali , Wechuck James B. , Goins William F. , Wolfe Darren , Glorioso Joseph C. , Ataai Mohammad M.
Published: August 2002

Herpes simplex virus type‐1 (HSV‐1) represents a unique vehicle for the introduction of foreign DNA to cells of a variety of tissues. The nature of the vector, the cell line used for propagation of the vector, and the culture conditions will significantly impact vector yield. An ideal vector should be deficient in genes essential for replication as well as those that contribute to its cytotoxicity. Advances in the engineering of replication‐defective HSV‐1 vectors to reduce vector‐associated cytotoxicity and attain sustained expression of target genes make HSV‐1 an attractive gene‐delivery vehicle. However, the yield of the less‐cytotoxic vectors produced in standard tissue‐culture systems is at least three order of magnitudes lower than that achieved with wild‐type virus. The low overall yield and the complexity involved in the preparation of HSV vectors at high concentrations represent major obstacles in use of replication‐defective HSV‐derived vectors in gene therapy applications. In this work, the dependence of the vector yield on the genetic background of the virus is examined. In addition, we investigated the production of the least toxic, lowest‐yield vector in a CellCube bioreactor system. After initial optimization of the operational parameters of the cellcube system, we were able to attain virus yields similar to or better than those values attained using the tissue culture flask system for vector production with significant savings with respect to time, labor, and cost. © 2002 John Wiley & Sons, Inc. Biotechnol Bioeng 77: 685–692, 2002; DOI 10.1002/bit.10162
Kinetic constants determination for an alkaline protease from Bacillus mojavensis using response surface methodology
Authors: Beg Qasim Khalil , Saxena R. K. , Gupta Rani
Published: August 2002

The kinetic constants for an alkaline protease from Bacillus mojavensis were determined using a central composite circumscribed design (CCCD) where concentration of substrate (casein) and the assay temperature were varied around their center point. The Km,Vmax, Kcat, activation energy (Ea) and temperature coefficient (q10) were determined and the values of these kinetic constants obtained were found comparable to that obtained with conventional methods. The Michaelis‐Menten constant (Km) for casein decreased with corresponding increase in Vmax, as reaction temperature was raised from 45–60°C. The protease exhibited Km of 0.0357 mg/ml, 0.0270 mg/ml, 0.0259 mg/ml, and 0.0250 mg/ml at 45, 50, 55, and 60°C, respectively, whereas Vmax values at these temperatures were 74.07, 99.01, 116.28, and 120.48 μg/ml/min, respectively, as determined by response surface methodology. The Arrhenius plot suggested that the enzyme undergoes thermal activation above 45°C until 60–65°C followed by thermal inactivation. Likewise, the energy of activation (Ea) was more between 45–55°C (9747 cal/mol) compared to Ea between 50–60°C (4162 cal/mol). © 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 78: 289–295, 2002.
Metabolic engineering of Pseudomonas putida for the utilization of parathion as a carbon and energy source
Authors: Walker Andy W , Keasling Jay D
Published: August 2002

Pseudomonas putida KT2442 was engineered to use the organophosphate pesticide parathion, a compound similar to other organophosphate pesticides and chemical warfare agents, as a source of carbon and energy. The initial step in the engineered degradation pathway was parathion hydrolysis by organophosphate hydrolase (OPH) to p‐nitrophenol (PNP) and diethyl thiophosphate, compounds that cannot be metabolized by P. putida KT2442. The gene encoding the native OPH (opd), with and without the secretory leader sequence, was cloned into broad‐host‐range plasmids under the control of tac and taclac promoters. Expression of opd from the tac promoter resulted in high OPH activity, whereas expression from the taclac promoter resulted in low activity. A plasmid‐harboring operons encoding enzymes for p‐nitrophenol transformation to β‐ketoadipate was transformed into P. putida allowing the organism to use 0.5 mM PNP as a carbon and energy source. Transformation of P. putida with the plasmids harboring opd and the PNP operons allowed the organism to utilize 0.8 mM parathion as a source of carbon and energy. Degradation studies showed that parathion formed a separate dense, non‐aqueous phase liquid phase but was still bioavailable. © 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 78: 715–721, 2002.