bluuebunny/crossref_metadata_2025_split huggingface dataset:
Properties of interpenetrating polymer network hydrogels composed of poly(vinyl alcohol) and poly(N‐isopropylacrylamide)
Authors: Kim Seon Jeong , Park Sang Jun , Chung Taek Dong , An Kay Hyeok , Kim Sun I. 
Published: June 2003

AbstractInterpenetrating polymer network (IPN) hydrogels based on poly(vinyl alcohol) and poly(N‐isopropylacrylamide) were prepared by the sequential‐IPN method. The IPN hydrogels were analyzed for sorption behavior of water at 35°C and at a relative humidity of 95% using a dynamic vapor sorption system, and water diffusion coefficients were calculated. Differential scanning calorimetry was used for the quantitative determination of the amounts of freezing and nonfreezing water. Free water contents in the IPN hydrogel of IPN1, IPN2, and IPN3 were 45.8, 37.9 and 33.1% in pure water, respectively. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2041–2045, 2003
Properties of EVM vulcanizates reinforced by in situ prepared sodium methacrylate
Authors: Du Aihua , Peng Zonglin , Zhang Yong , Zhang Yinxi 
Published: June 2003

AbstractEthylene–vinyl acetate copolymer (EVM) vulcanizates with good mechanical properties and high transparency were obtained using sodium methacrylate (NaMAA) as a reinforcing agent. Sodium methacrylate was in situ prepared through the neutralization of sodium hydroxide (NaOH) and methacrylic acid (MAA) in an EVM and used to reinforce the EVM cured by dicumyl peroxide (DCP). Different factors such as the DCP content, NaMAA content, and the mol ratio of NaOH/MAA were included to study their effects on the mechanical properties, optical properties, stress‐relaxation behavior, and crosslink structure of the EVM vulcanizates. The rheological behavior of the EVM compounds was also investigated and compared with that of the high abrasion furnace carbon black (HAF)/EVM compounds. The experimental results show that with an increase of the NaMAA content the curing rate index (CR) of the EVM compounds is greatly speeded up, while the Mooney viscosities of the compounds remain nearly unchanged. The mechanical properties and optical properties of the NaMAA‐reinforced EVM vulcanizates depend on the NaMAA content and the mol ratio of NaOH/MAA. The formulation of DCP of 3 phr and a NaOH/MAA mol ratio of 1.0 is recommended for the EVM vulcanizate with high mechanical properties. At a given NaOH/MAA mol ratio of 1.0, all the EVM vulcanizates are transparent and the light transmission is over 76% in the NaMAA content range of 10–50 phr. The NaMAA/EVM vulcanizates show faster stress relaxation and more obvious stress‐softening effects than those of the HAF/EVM vulcanizates. Crosslink density analysis indicated that the EVM vulcanizates contain both covalent and ionic bonds. The ionic crosslink densities greatly increase with an increasing NaMAA content. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2192–2200, 2003
Studies on second harmonic generation efficiency by a series of chiral polyesters
Authors: Philip Biju , Sreekumar K. 
Published: June 2003

AbstractA series of optically active main‐chain polyesters were synthesized by high‐temperature polycondensation from biphenolic azo chromophores, (2R,3R)‐(+)‐diethyl tartrate and terephthaloyl chloride. The polyesters showed glass transition temperatures in the range of 100–135°C and were thermally stable to 350°C. The second harmonic generation efficiency of the polyesters was studied by the powder method and as thin films with 2‐methyl‐4‐nitroaniline as a reference. The SHG efficiency of the polymers was compared with that of low molecular weight chromophores. The polymers with chiral units showed good second harmonic generation efficiency. The SH signal also showed good temporal stability. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 11: 2468–2473, 2003
Chemically treated hard gelatin capsules for colon‐targeted drug delivery: A novel approach
Authors: Bajpai S. K. , Bajpai M. , Dengre R. 
Published: June 2003

AbstractHard gelatin capsules, containing riboflavin‐loaded poly (N‐viny1–2‐pyrrolidone)‐polyacrylamide cylindrical hydrogels, were modified chemically by treating with an aqueous formaldehyde solution for the purpose of delayed release of drug along the gastrointestinal tract. The tdis (disintegration time) of capsules was studied as a function of concentration of formaldehyde solution and the treatment time. The dynamic release of vitamin B2 was studied as a function of crosslinking ratio of the hydrogels. The device studied seems to have potential to be used for colon‐targeted drug delivery. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2277–2282, 2003
Barrier properties of a thermotropic liquid‐crystalline polymer
Authors: Ramathal Hansel , Lawal Adeniyi 
Published: June 2003

AbstractA developmental thermotropic liquid‐crystalline polymer (TLCP) made by Eastman (trade name LN001) was used for barrier property studies. This material is a highly aromatic TLCP with a Tm of 332°C. A permeability study was carried out to determine the chemical resistance of the TLCP. The permeability of methanol and toluene through a membrane of the TLCP was studied using a two‐part cell and a gas chromatograph to monitor the flux. The membranes of the TLCP and LDPE (as control) were made by compression molding. Both solvents had higher permeability through LDPE than TLCP and that of toluene was higher than that of methanol. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2457–2463, 2003
Electrotransport of organic electrolytes through 2‐(dimethylamino)ethyl methacrylate–grafted polyethylene films and their separation and concentration
Authors: Yamada Kazunori , Taki Takayuki , Sato Kimihito , Hirata Mitsuo 
Published: June 2003

AbstractOrganic electrolytes with negatively chargeable functional groups such as benzoic acid (BA, weak acid), benzenesulfonic acid (BSA, strong acid), and p‐aminobenzoic acid (p‐ABA, ampholyte) were concentrated through polyethylene (PE) films photografted with 2‐(dimethylamino)ethyl methacrylate (DMAEMA) by electrotransport. The permeabilities of DMAEMA‐grafted PE (PE‐g‐PDMAEMA) films to BA and BSA were considerably increased by the application of direct current at pH 6. BA and BSA could be selectively permeated from the respective binary BA/phenyl‐1,2‐ethandiol (PhED, neutral) and BSA/PhED mixtures by making use of the difference in their permeabilities. In addition, BSA was selectively permeated from the binary BSA/BA mixtures. The organic electrolytes mentioned above were transported against their concentration gradient toward the anode side and their degrees of concentration went up to 90% by the continuous application of direct current. The degrees of concentration for organic electrolytes obtained by electrotransport in this study were slightly higher than those obtained by the uphill transport using the pH difference across the PE‐g‐PDMAEMA film, and the concentration time was considerably shortened. It was made clear that the electrotransport through the PE‐g‐PDMAEMA films is one of the effective techniques to selectively separate or concentrate organic electrolytes with negatively chargeable functional groups. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2535–2544, 2003
Study of high thermal conductive epoxy resins containing controlled high‐order structures
Authors: Akatsuka Masaki , Takezawa Yoshitaka 
Published: June 2003

AbstractHeat is transported by phonons through dielectric solids such as ceramics and organic insulating resins. Especially in organic insulating resins, phonons scatter intensely mainly by their amorphous structure, which affects their thermal conductivities, usually 1 to 3 orders lower than those of ceramics and metals. Here, we show that by the thermosetting resin system with a crystal‐like structure that is microscopic anisotropy, the thermal conductivities of the resin themselves can be improved while keeping their macroscopic isotropy. We studied four kinds of diepoxy monomers with a biphenyl group or two phenyl benzoate groups as mesogens, and cured them thermally with an aromatic diamine curing agent. These thermal conductivities were maximally 5 times higher than that of conventional epoxy resins because mesogens were highly ordered to form crystal‐like structures to suppress phonon scattering. We also succeeded in the direct confirmation of the existence of crystal‐like structures in the epoxy resins by TEM observation. These results suggest a novel strategy to improve thermal conductivities of insulating resins themselves by controlling the high‐order structures. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2464–2467, 2003
Electron spin resonance spectroscopy study on reduction of constrained‐geometry catalyst systems
Authors: Ye Zhibin , Wang Wen‐Jun , Zhu Shiping 
Published: June 2003

AbstractThe reduction of a constrained‐geometry catalyst (CGCTiMe2) activated with a series of cocatalysts, including modified methylaluminoxane (MMAO), tris(pentafluorophenyl) borane [B(C6F5)3], and combined B(C6F5)3/MMAO, was experimentally investigated using an on‐line electron spin resonance spectroscopy (ESR) technique. The effects of the solvent type, cocatalyst/catalyst ratio, and temperature on the reduction were examined. In the CGCTiMe2/MMAO system, increasing the Al/Ti molar ratio from 20 to 250 significantly increased the Ti(III) content. Adding trimethylaluminum to the system lowered the Ti(III) content. Three trivalent Ti species, Ti(a) (g = 1.972), Ti(b) [g = 1.992, α(H) = 7.4 G], and Ti(c) (g = 1.995), were observed. In the CGCMe2/B(C6F5)3 system, only one trivalent Ti species (g = 1.988) was observed. The CGCTiMe2/B(C6F5)3 system was more stable to reduction than the CGCTiMe2/MMAO system. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2474–2482, 2003
Synthesis of 1‐Methyl‐5‐(pyrazol‐3‐ and ‐5‐yl‐ and 1, 2, 4‐triazol‐3‐ and 5‐yl)‐1, 2, 3, 6‐tetrahydropyridine Derivatives and Their Evaluation as Muscarinic Receptor Ligands
Authors: Del Giudice Maria Rosaria , Mustazza Carlo , Borioni Anna , Gatta Franco , Tayebati Khosrow , Amenta Francesco , Tucci Paolo , Pieretti Stefano 
Published: June 2003

AbstractA series of 1‐methyl‐5‐(pyrazol‐3‐ and ‐5‐yl‐ and 1, 2, 4‐triazol‐3‐ and 5‐yl)‐1, 2, 3, 6‐tetrahydropyridine derivatives structurally related to arecoline were synthesized and evaluated on M1, M2, and M3 muscarinic receptors using [3H] pirenzepine and [3H] NMS as ligands. The binding affinity depended on the position and size of the substituents. The most interesting compounds were further evaluated in functional studies on isolated organs and in vivo for cholinergic side effects. Compounds 5l and 6i good M1 and M3 antagonistic properties in vitro and were devoid of cholinergic side effects in vivo.
Synthesis of 2‐Methylsulfanyl‐1H‐imidazoles as Novel Non‐nucleoside Reverse Transcriptase Inhibitors (NNRTIs)
Authors: Loksha Yasser M. , El‐Badawi Mahmoud A. , El‐Barbary Ahmed A. , Pedersen Erik B. , Nielsen Claus 
Published: June 2003

Abstractα‐Aminoketone hydrochlorides 2a—d were synthesized by Dakin‐West reaction from L‐phenylalanine and L‐cyclohexylalanine followed by hydrolysis in acidic medium. Treatment of 2a—d with aqueous potassium thiocyanate afforded 1, 3‐imidazole‐2‐thiones 3a—d which were alkylated with methyl iodide to give 2‐methylsulfanyl‐1H‐imidazoles 4a—d with 4‐benzyl/4‐cyclohexylmethyl and 5‐ethyl/5‐isopropyl substituents. Coupling of 4a—d with ethoxymethyl chloride or benzyloxymethyl chloride furnished N‐1 5a—d and N‐3 6a—h alkylated products. The synthesised compounds were tested for their activity against HIV‐1. The most active compounds have a cyclohexylmethyl group in the 5‐position of 6 and showed an activity against HIV‐1 comparable to the activity of Nevirapine.
Synthesis and Cytotoxicity of Substituted Ethyl 2‐Phenacyl‐3‐phenylpyrrole‐4‐carboxylates
Authors: Evans Michael A. , Smith Daniel C. , Holub Justin M. , Argenti Anthony , Hoff Mafoloe , Dalglish Gerard A. , Wilson Donna L. , Taylor Brett M. , Berkowitz Joshua D. , Burnham Bruce S. , Krumpe Keith , Gupton John T. , Scarlett Tanya C. , Durham, Jr Richard W. , Hall Iris H. 
Published: June 2003

AbstractThe substituted ethyl‐2‐phenacyl‐3‐phenylpyrrole‐4‐carboxylates were synthesized by a condensation of a beta‐chloroenal and an alpha‐aminoketone under neutral conditions. They proved to be potent cytotoxic agents against the growth of murine L1210 and P388 leukemias and human HL‐60 promyelocytic leukemia, HuT‐78 lymphoma, and HeLa‐S3 uterine carcinoma. Selective compounds were active against the growth of Tmolt3 and Tmolt4 leukemias and THP‐1 acute monocytic leukemia, liver Hepe‐2, ovary 1‐A9, ileum HCT‐8 adenocarcinoma, and osteosarcoma HSO. A mode of action study in HL‐60 cells demonstrated that DNA and protein syntheses were inhibited after 60[TH]min at 100[TH]μM. DNA and RNA polymerases, PRPP‐amido transferase, dihydrofolate reductase, thymidylate synthase, and TMP kinase activities were interfered with by the agent with reduction of d[NTP] pools. Nonspecific interaction with the bases of DNA and cross‐linking of the DNA may play a role in the mode of action of these carboxylates.
Bioelectromagnetics in morphogenesis
Authors: Levin Michael 
Published: June 2003

AbstractUnderstanding the factors that allow biological systems to reliably self‐assemble consistent, highly complex, four dimensional patterns on many scales is crucial for the biomedicine of cancer, regeneration, and birth defects. The role of chemical signaling factors in controlling embryonic morphogenesis has been a central focus in modern developmental biology. While the role of tensile forces is also beginning to be appreciated, another major aspect of physics remains largely neglected by molecular embryology: electromagnetic fields and radiations. The continued progress of molecular approaches to understanding biological form and function in the post genome era now requires the merging of genetics with functional understanding of biophysics and physiology in vivo. The literature contains much data hinting at an important role for bioelectromagnetic phenomena as a mediator of morphogenetic information in many contexts relevant to embryonic development. This review attempts to highlight briefly some of the most promising (and often underappreciated) findings that are of high relevance for understanding the biophysical factors mediating morphogenetic signals in biological systems. These data originate from contexts including embryonic development, neoplasm, and regeneration. Bioelectromagnetics 24:295‐315, 2003. © 2003 Wiley‐Liss, Inc.
Effect of millimeter waves on cyclophosphamide induced suppression of T cell functions
Authors: Makar Vera , Logani Mahendra , Szabo Imre , Ziskin Marvin 
Published: June 2003

AbstractThe effects of low power electromagnetic millimeter waves (MWs) on T cell activation, proliferation, and effector functions were studied in BALB/c mice. These functions are important in T‐lymphocyte mediated immune responses. The MW exposure characteristics were: frequency = 42.2 GHz; peak incident power density = 31 ± 5 mW/cm2, peak specific absorption rate (SAR) at the skin surface = 622 ± 100 W/kg; duration 30 min daily for 3 days. MW treatment was applied to the nasal area. The mice were additionally treated with cyclophosphamide (CPA), 100 mg/kg, a commonly used immunosuppressant and anticancer drug. Four groups of animals were used in each experiment: naive control (Naive), CPA treated (CPA), CPA treated and sham exposed (CPA + Sham), and CPA treated and MW exposed (CPA + MW). MW irradiation of CPA treated mice significantly augmented the proliferation recovery process of T cells (splenocytes). A statistically significant difference (P < .05) between CPA and CPA + MW groups was observed when cells were stimulated with an antigen. On the other hand, no statistically significant difference between CPA and CPA‐Sham groups was observed. Based on flow cytometry of CD4+ and CD8+ T cells, two major classes of T cells, we show that CD4+ T cells play an important role in the proliferation recovery process. MW exposure restored the CD25 surface activation marker expression in CD4+ T cells. We next examined the effector function of purified CD4+ T cells by measuring their cytokine profile. No changes were observed after MW irradiation in interleukin‐10 (IL‐10) level, a Th2 type cytokine, while the level of interferon‐γ (IFN‐γ), a Th1 type cytokine was increased twofold. Our results indicate that MWs enhance the effector function of CD4+ T cells preferentially, through initiating a Th1 type of immune response. This was further supported by our observation of a significant enhancement of tumor necrosis factor‐α (TNF‐α) production by peritoneal macrophage's in CPA treated mice. The present study shows MWs ameliorate the immunosuppressive effects of CPA by augmenting the proliferation of splenocytes, and altering the activation and effector functions of CD4+ T cells. Bioelectromagnetics 24:356‐365, 2003. © 2003 Wiley‐Liss, Inc.
Phosphate metabolites in muscular contraction caused by magnetic stimulation
Authors: Chiba Atsushi , Inase Masahiko 
Published: June 2003

AbstractThe metabolism of high energy phosphates during muscular contraction due to direct electrical stimulation, indirect stimulation via nerve excitation, and magnetic stimulation was studied in isolated muscles (frog sartorius muscles) by 31P nuclear magnetic resonance (31P‐NMR). Twitch amplitudes elicited by each stimulus were measured alternatively at 3 mm displacement loading and 5 g weight. Both the creatine/inorganic phosphate (PCr/Pi) and pH changes were more marked in direct electrical stimulation than in magnetic stimulation. The muscular contraction caused by magnetic stimulation showed less fatigue than that caused by direct electrical muscular stimulation. Bioelectromagnetics 24:366‐371, 2003. © 2003 Wiley‐Liss, Inc.
Analysis of anisotropic diamagnetic susceptibility of a bull sperm
Authors: Emura Runa , Takeuchi Tetsuya , Nakaoka Yasuo , Higashi Terumasa 
Published: June 2003

AbstractBull sperm and paramecium cilium were exposed to uniform static magnetic fields to observe their magnetic orientations and measure their anisotropic diamagnetic susceptibility (δχ) for each. The prepared samples were whole bull sperm, bull sperm flat heads, and paramecium cilia, because bull sperm tails in a perfect condition could not be prepared. The whole bull sperm and the bull sperm heads became oriented perpendicular to the magnetic fields (1.7 Tesla maximum), while the paramecium cilia became parallel to the magnetic fields (8 Tesla maximum). A whole bull sperm, a bull sperm head, and a paramecium cilium were photometrically studied to obtain δχ for each, which were estimated to be 1 × 10−19, 3 × 10−19, and 2 × 10−20 J/T2, respectively. δχ of a sperm flagellum was estimated from the measured value of δχ of the paramecium cilium, which agrees well with the difference between δχ of the whole sperm and the sperm head. Additionally, this difference of δχ almost coincides with the δχ values calculated from δχ of tubulin, as well. If the magnetic effect on biological systems is solved and the magnetic orientation correlates with it, δχ will become the quantitative index of the effect. Bioelectromagnetics 24:347‐355, 2003. © 2003 Wiley‐Liss, Inc.
Effects of a 50 Hz sinusoidal magnetic field on cell adhesion molecule expression in two human osteosarcoma cell lines (MG‐63 and Saos‐2)
Authors: Santini Maria Teresa , Rainaldi Gabriella , Ferrante Antonella , Indovina Pietro Luigi , Vecchia Paolo , Donelli Gianfranco 
Published: June 2003

AbstractThe possibility that a sinusoidal 50 Hz magnetic field with a magnetic flux density of 0.5 mT can induce variations in the expression of cell adhesion molecules (CAMs) in two human osteosarcoma cell lines (MG‐63 and Saos‐2) was investigated. In particular, the expression of two important integrins, VLA‐2, the receptor for collagen, and VLA‐5, the receptor for fibronectin, as well as CD44, were examined in both cell lines after these had been exposed for 7 and 14 days to a 50 Hz, 0.5 mT field. Cell surface morphology (scanning electron microscopy), cell growth characteristics (growth curves and cell cycle phase distribution), and cell death (necrosis and apoptosis) were also examined. The results demonstrate that no variations in surface morphology and cell death occurred between control and exposed cells in both MG‐63 and Saos‐2 cells, while significant changes were noted in cell growth and fibronectin and CD44 expression in MG‐63 cells. The results are discussed in view of the important role that CAMs play in controlling various cancer cell functions, particularly proliferation and metastasis. Bioelectromagnetics 24:327‐338, 2003. © 2003 Wiley‐Liss, Inc.
The evolution of floral homeotic gene function
Authors: Irish Vivian F. 
Published: June 2003

AbstractPlant MADS‐box genes encode transcriptional regulators that are critical for a number of developmental processes. In the angiosperms (the flowering plants), these include the specification of floral organ identities, flowering time and fruit development. It appears that the MADS box gene family has undergone considerable gene duplication and sequence divergence within the angiosperms. Here I discuss the possibility that these events have allowed the recruitment of these genes to new developmental pathways in particular angiosperm lineages. Recent analyses of sequence changes, expression patterns and, in a few cases, gene function are beginning to provide tantalizing evidence for deciphering when and how such genetic diversification has led to particular morphological innovations. In the future, comparative studies of large numbers of species will be required to assess the extent of such variation as well as to fully understand the mechanisms by which evolution of these developmental regulators has played a role in shaping new morphologies. BioEssays 25:637–646, 2003. © 2003 Wiley Periodicals, Inc.
What's your position? the Xenopus cement gland as a paradigm of regional specification
Authors: Wardle Fiona C. , Sive Hazel L. 
Published: June 2003

AbstractThe correct positioning of organs during embryonic development requires multiple cues. The Xenopus cement gland is a mucus‐secreting epithelium that is a simple model for organogenesis, allowing detailed analysis of this complex process. The cement gland forms at a conserved anterior position, where embryonic ectoderm and endoderm touch. In all deuterostomes, this region will form the stomodeum (primitive mouth) and, in some aquatic larva, will also form a cement gland. In recent years, a model has been put forward suggesting that an intermediate level of BMP signaling in the ectoderm leads to cement gland formation. We propose an alternative model whereby, during gastrulation, the cement gland (CG) is positioned by the overlap of three domains, corresponding to anterodorsal identity (AD), ventrolateral identity (VL), and ectodermal outer layer identity (EO), defining the equation (AD + VL + EO = CG). Anterodorsal identity requires a contribution by the transcription factor Otx2 while ventrolateral identity requires the BMP4 signaling pathway. These postional cues are integrated to activate cement gland differentiation. This integration appears to require intermediate steps, including expression of pitx genes, and members of the ATF/CREB and Ets transcription factor families. BioEssays 25:717–726, 2003. © 2003 Wiley Periodicals, Inc.