bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dipeptidyl Peptidase-4 Inhibition by Vildagliptin and the Effect on Insulin Secretion and Action in Response to Meal Ingestion in Type 2 Diabetes
Authors: Dalla Man Chiara , Bock Gerlies , Giesler Paula D. , Serra Denise B. , Ligueros Saylan Monica , Foley James E. , Camilleri Michael , Toffolo Gianna , Cobelli Claudio , Rizza Robert A. , Vella Adrian 
Published: October 2008

OBJECTIVE—The purpose of this study was to determine the mechanism by which dipeptidyl peptidase-4 inhibitors lower postprandial glucose concentrations.
RESEARCH DESIGN AND METHODS—We measured insulin secretion and action as well as glucose effectiveness in 14 subjects with type 2 diabetes who received vildagliptin (50 mg b.i.d.) or placebo for 10 days in random order separated by a 3-week washout. On day 9 of each period, subjects ate a mixed meal. Insulin sensitivity (SI), glucose effectiveness, and β-cell responsivity indexes were estimated using the oral glucose and C-peptide minimal models. At 300 min 0.02 unit/kg insulin was administered intravenously.
RESULTS—Vildagliptin reduced postprandial glucose concentrations (905 ± 94 vs. 1,008 ± 104 mmol/6 h, P = 0.02). Vildagliptin did not alter net SI (7.71 ± 1.28 vs. 6.41 ± 0.84 10−4 dl · kg−1 · min−1 · μU−1 · ml−1, P = 0.13) or glucose effectiveness (0.019 ± 0.002 vs. 0.018 ± 0.002 dl · kg−1 · min−1, P = 0.65). However, the net β-cell responsivity index was increased (35.7 ± 5.2 vs. 28.9 ± 5.2 10−9 min−1, P = 0.03) as was total disposition index (381 ± 48 vs. 261 ± 35 10−14 dl · kg−1 · min−2 · pmol−1 · l−1, P = 0.006). Vildagliptin lowered postprandial glucagon concentrations (27.0 ± 1.1 vs. 29.7 ± 1.5 μg · l−1 · 6 h−1, P = 0.03), especially after administration of exogenous insulin (81.5 ± 6.4 vs. 99.3 ± 5.6 ng/l, P = 0.02).
CONCLUSIONS—Vildagliptin lowers postprandial glucose concentrations by stimulating insulin secretion and suppressing glucagon secretion but not by altered insulin action or glucose effectiveness. A novel observation is that vildagliptin alters α-cell responsiveness to insulin administration, but the significance of this action is as yet unclear.
Effect of Chitin and Abamectin on Meloidogyne Incognita Infesting Rapeseed
Authors: Korayem Ahmed , Youssef Mahmoud , Mohamed Moawad 
Published: October 2008

Effect of Chitin and Abamectin onMeloidogyne IncognitaInfesting RapeseedThe tested rates of chitin (2, 4 and 8 g/m2) significantly (p ± 0.05 and 0.01) reduced the number of galls, egg masses, females and the second stage juveniles (J2) in oilseed rape cvAD201 under field conditions. The plant growth parameters as length and weight of shoots increased at all rates of chitin compared to the untreated check. When using abamectin at the concentrations of 500, 1000 and 1500 ppm, it significantly (p ± 0.05) reduced the above listed nematode criteria and enhanced the plant growth criteria.
Sickle Cell Disease Summit: From clinical and research disparity to action
Authors: Hassell Kathryn , Pace Betty , Wang Winfred , Kulkarni Roshni , Luban Naomi , Johnson Cage S. , Eckman James , Lane Peter , Woods William G. 
Published: October 2008

AbstractThe American Society of Pediatric Hematology/Oncology Sickle Cell Summit brought together a broad range of constituencies to identify a unified approach to healthcare and research disparities for sickle cell disease. Recommendations included the following: (1) speak with a unified voice representing all constituencies; (2) optimize access to care from knowledgeable health care providers and create a medical home for all individuals with the disease; (3) utilize population‐based surveillance to measure outcomes; (4) develop overall approaches to basic, translational, clinical, and health services research; (5) enhance the community role in advocacy, education, service, and fundraising. Taskforces were identified to effect implementation. Am. J. Hematol., 2009. © 2008 Wiley‐Liss, Inc.
An effect of OMMT on the anti‐reversion in NR/CR blend system
Authors: Zhang Peng , Huang Guangsu , Liu Zhiyuan 
Published: October 2008

AbstractThe influence of dispersed organomodified montmorillonite (OMMT) on curing behaviors of natural rubber (NR)/chloroprene rubber (CR) blend was investigated. The preparing procedure includes premixed rubber individually with its additives and then the two components were blended according to gum weight ratio for NR to CR is 75/25. Sulfur was chosen as the vulcanizing agent, and the research on vulcanization was carried through the rotor‐Rheometer at 143°C. Transmission electron microscopy showed the dispersion of OMMT in the rubber blends and detected little OMMT migrated into the NR phase. The scorch time (t10), optimum vulcanizing time (t90), and reversion phenomenon were both measured by the curing curve; meanwhile, the crosslinking densities and mechanical properties were determined through equilibrium swelling‐method, magnetic resonance crosslink density spectrometer, and tensile tests. By comparing the test results, an interesting phenomenon was discovered and furthermore was verified that the addition of OMMT can obviously modify the reversion resistance of the binary blend. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Mechanical properties of polypropylene/clay nanocomposites: Effect of clay content, polymer/clay compatibility, and processing conditions
Authors: Tarapow J. A. , Bernal C. R. , Alvarez V. A. 
Published: October 2008

AbstractIn this work, polypropylene/clay nanocomposites with 0.5, 1, 3, and 5 wt % of montmorillonite (MMT) (unmodified clay) were prepared by intensive mixing at 50 rpm and 10 min of mixing. For the highest clay content (5 wt %), the initial materials or the processing conditions were changed to study their independent effect. On one hand, 10 wt % of PP‐graft‐MA (PP‐g‐MA) was incorporated or MMT was replaced by organomodified clays (C10A and C30B). On the other side, for the initial system, the speed of rotation (100 and 150 rpm) and the mixing time (5 and 15 min) were altered. In all cases, the state of the clay inside the matrix (DRX), the degree of dispersion in the micro (SEM) and nano (TEM) scales, and the rheological and mechanical properties were analyzed. It was found that the stiffness increased with clay content, whereas tensile and impact strength did not significantly change. Although intercalated structures were observed in the composites with unmodified clay, in the composites with modified clay or PP‐g‐MA, improved dispersion of clay in PP was found. The mechanical properties increased accordingly. The degree of dispersion of the filler in the matrix appeared to be unaffected by the changes in the processing conditions introduced. Finally, the elastic modulus was modeled by using an effective filler‐parameter model based on Halpin–Tsai equations, which also allowed estimating the relative degree of dispersion. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Comparison of tensile, thermal, and thermo‐mechanical properties of polyester filaments having different cross‐sectional shape
Authors: Hasan M. M. Badrul , Dutschk V. , Brünig H. , Mäder E. , Häussler L. , Hässler R. , Cherif Ch. , Heinrich G. 
Published: October 2008

AbstractOne of the most important morphological features of fibers is their cross‐sectional shape. Nowadays, the circular fiber cross‐section is the most common shape of melt‐spun man‐made fibers. Other shapes are beginning to emerge for a variety of reasons such as performance, comfort, pilling propensity, bulkiness, tactility, processing etc. The filaments' cross‐section can be easily varied by changing the spinneret hole shape. Synthetic fibers that are predominantly spun by the melt spinning method with spinnerets having the noncircular hole geometry are called profiled or noncircular fibers. Modifications of the fiber cross‐section allow designing surface properties in yarn and fabric. However, the effect of profiled fibers on yarn properties has not been well documented yet. In this article, the influence of different filament cross‐section geometry on fiber properties was studied. PET (polyethylene terephthalate) filament yarns having two different cross‐sectional shaped filaments, circular and cruciform, were manufactured by melt spinning. Differences in tensile properties of filament yarn and as well as of individual filament depending on the cross‐sectional type were studied and revealed. More over, thermal and thermomechanical properties of filament yarn of both the cross‐sections were studied and revealed by DSC and TMA method, respectively. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
A study on formation and stability of epoxy resin inverse concentrated water/oil emulsion
Authors: Wang Jianli , Du Zhongjie , Li Congju , Li Hangquan , Zhang Chen 
Published: October 2008

AbstractInverse concentrated emulsions were prepared using aqueous colloidal silica suspension as the hydrophilic dispersed phase and a solution of diglycidyl ether of bisphenol‐A (DGEBA), its curing agent polyamide resin, low molecular weight 650, surfactant nonyl phenol polyoxyethylene ether (NPE‐4) in 4‐methyl‐2‐pentanon as the continuous phase, which was expected to be used as the precursors of preparation of porous epoxy resins. The stability, i.e., the resistance to phase separation was studied. The effects of various parameters on the stability of the concentrated emulsions were investigated. The colloidal silica can strengthen the steric repulsion in the system and improve the stability. Viscosity of both phases played a major role in the stability. Precuring of the continuous phase provided an increased initial viscosity and enhanced the stability. Lower volume fraction of the dispersed phase can help to maintain stability of the concentrated emulsions. Properly increasing the curing rate, the concentrated emulsions may acquire a high viscosity in a short time, which retarded the phase separation. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
The impact of polypropylene‐graft‐maleic anhydride on the crystallization and dynamic mechanical properties of isotactic polypropylene
Authors: Harper David P. , Laborie Marie‐Pierre G. , Wolcott Michael P. 
Published: October 2008

AbstractDifferential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) were used to identify the mechanisms that lead to differences in the mechanical behavior of formulations of polypropylene blended with maleated polypropylene (MAPP) copolymers. MAPP lowered the melting temperature of PP indicating that less stable crystals were formed possibly because of cocrystallization of PP and MAPP. Crystallization kinetics revealed that copolymers do not change the rate of crystal growth, but may retard nucleation leading to a more spherulitic morphology. The dynamic storage modulus slightly increased in the glassy region with the small addition amounts of MAPP, while mechanical dampening systematically decreased with MAPP addition. An analysis of the viscoelastic behavior did not reveal any real differences in molecular coupling around the β‐transition of PP with the addition of the MAPP copolymer. At low addition levels, MAPP does not appear to have a significant impact on the viscoelastic properties of the polymer blend. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Design and fabrication of SCPOF preform doped with rare earth complexes
Authors: Wu Wenxuan , Xu Jie , Luo Yanhua , Yang Jiwen , Ming Hai , Chen Biao , Zhang Qijin 
Published: October 2008

AbstractSegmented‐cladding fibers (SCF) consist of a uniform core of high refractive index and a cladding with regions of high and low refractive index alternating angularly, which can effectively realize single mode with a large core diameter. Because polymer optical fibers are usually of large diameter, theoretical model for SCF was further extended to segmented‐cladding polymer optical fibers (SCPOF) doped with rare earth complex in this article. On the basis of the physical principle, a material model for SCPOF was established, from which refractive index and glass transition temperature of polymer materials was predetermined for the core and cladding of SCPOF, respectively. According to the model, a preform for SCPOF was fabricated with the core doped with Eu(DBM)3Phen that has characteristic emission at 613 nm under excitation at 365 nm. From results of fluorescence photograph, it is clearly seen that the expected preform has been obtained by a two‐step method developed in this work. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Structural and thermal characterization of hybrid materials based on TEOS and DCN
Authors: Trejo‐Durán M. , Martínez‐Richa A. , Vera‐Graziano R. , Alvarado‐Méndez E. , Castaño V. M. 
Published: October 2008

AbstractSolution and solid‐state Silicon‐29 NMR spectroscopy, X‐ray diffraction (WAXS), infrared spectroscopy (IR), thermogravimetric analysis (TGA), and differential scanning calorimetric were used for the characterization of organic–inorganic hybrids, obtained from 4‐[[5‐dichloromethylsilyl]pentyl]oxy]‐cyanobenzene (DCN) and tetraethoxysilane (TEOS). Presence of reaction intermediates during chemical reactions was characterized by NMR. The hybrids are mainly composed of a siloxane copolymer with silicate units. Copolymer has pendant groups of pentyl‐oxy‐cyanobenzene that behave as chromophores. The nature of ordered–disordered phases was analyzed by X‐ray diffraction, differential scanning calorimetry, and thermogravimetric analysis. Ordered phase has a mesogenic structure containing the siloxane copolymer. The disordered phase is mainly silica glass. Molecular modeling for an idealized section of the copolymer suggests that pentyl‐oxy‐cyanobenzene side‐chains align as rigid mesogens along the polymer backbone. Hybrids present self diffraction patterns in coherent luminous rings forms. These patterns indicate the presence of nonlinear optic (NLO) properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Influence of silicon carbide filler on mechanical and dielectric properties of glass fabric reinforced epoxy composites
Authors: Suresha B. , Chandramohan G. , Renukappa N. M. , Siddaramaiah  
Published: October 2008

AbstractFiber‐reinforced polymeric composites (FRPCs) have emerged as an important material for automotive, aerospace, and other engineering applications because of their light weight, design flexibility, ease of manufacturing, and improved mechanical performance. In this study, glass‐epoxy (G‐E) and silicon carbide filled glass‐epoxy (SiC‐G‐E) composite systems have been fabricated using hand lay‐up technique. The mechanical properties such as tensile strength, tensile modulus, elongation at break, flexural strength, and hardness have been investigated in accordance with ASTM standards. From the experimental investigations, it has been found that the tensile strength, flexural strength, and hardness of the glass reinforced epoxy composite increased with the inclusion of SiC filler. The results of the SiC (5 wt %)‐G‐E composite showed higher mechanical properties compared to G‐E system. The dielectric properties such as dielectric constant (permittivity), tan delta, dielectric loss, and AC conductivity of these composites have been evaluated. A drastic reduction in dielectric constant after incorporation of conducting SiC filler into epoxy composite has been observed. Scanning electron microscopy (SEM) photomicrographs of the fractured samples revealed various aspects of the fractured surfaces. The failure modes of the tensile fractured surfaces have also been reported. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis of thermoresponsive polymeric micelles of PNIPAAm‐b‐OMMA as a drug carrier for loading and controlled release of prednisolone
Authors: Li Wei , Tu Weixia , Cao Dapeng 
Published: October 2008

AbstractWe synthesized a drug delivery system of poly(N‐isopropylacrylamide)‐b‐oligo(methyl methacrylate) (PNIPAAm‐b‐OMMA) via polycondensation of two homopolymers in 1,4‐dioxane. The products are characterized by FT‐IR and 1H‐NMR spectra and TEM. The PNIPAAm‐b‐OMMA copolymer micelles in aqueous solution present the same lower critical solution temperature (LCST) as the unmodified PNIPAAm, owing to the formation of a core–shell micellar structure that the hydrophilic shell shields the hydrophobic inner OMMA core from interacting with water. The micelle carriers exhibit two heterogeneous microdomains: a hydrophobic inner core capable of highly solubilizing hydrophobic prednisolone molecules, plus a hydrated outer shell that stabilizes this micellar structure below its LCST. Moreover, the micelle carriers show reversible thermoresponsive aggregation/dispersion in response to temperature cycles through the LCST. By using the antiinflammation drug prednisolone as model drug, it is found that the PNIPAAm‐b‐OMMA drug carrier could prolong the release time and control the release amount by changing the temperature. Accordingly, this copolymer micelle may provide as an effective drug carrier for drug control and release. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Multifunctional peroxide as alternative crosslink agents for dynamically vulcanized epoxidized natural rubber/polypropylene blends
Authors: Thitithammawong A. , Nakason C. , Sahakaro K. , Noordermeer J. W. M. 
Published: October 2008

AbstractCommonly used dicumyl peroxide (DCP) in combination with coagent, triallyl cyanurate (TAC), as a crosslinking agent is well acceptable for dynamically vulcanized rubber phase of thermoplastic vulcanizates (TPVs). However, it generally produces volatile decomposition products, which cause a typical unpleasant smell and a blooming phenomenon. In this work, influence of two types of multifunctional peroxides: 2,4‐diallyloxy‐6‐tert‐butylperoxy‐1,3,5‐triazine (DTBT) and 1‐(2‐tert‐butylperoxyisopropyl)‐3‐isopropenyl benzene (TBIB), on properties of TPVs based on epoxidized natural rubber (ENR)/polypropylene (PP) blends were investigated. The conventional peroxide/coagent combinations, i.e., DCP/TAC and tert‐butyl cumyl peroxide (TBCP)/α‐methyl styrene (α‐MeS) were also used to prepare the TPVs for a comparison purpose. The TPVs with multifunctional peroxide, DTBT, provided good mechanical properties and phase morphology of small dispersed vulcanized rubber domains in the PP matrix which were comparable with the DCP/TAC cured TPVs. However, the TPVs with TBIB/α‐MeS and TBCP/α‐MeS showed comparatively low values of the tensile properties as well as rather large phase morphology. The results were interpreted by three main factors: the kinetic aspects of the various peroxides, solubility parameters of respective peroxide/coagent combinations in the ENR and PP phases, and the tendency to form unpleasantly smelling byproducts. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Conducting polymer composites of multiwalled carbon nanotube filled doped polyaniline
Authors: Yılmaz Faris , Küçükyavuz Zuhal 
Published: October 2008

AbstractA multiwalled carbon nanotube (c‐MWNT)/polyaniline (PANI) composite was synthesized by an in situ chemical oxidative polymerization process. With the carbon nanotube loading increased from 0 to 30 wt %, the conductivity also increased and became weakly temperature‐dependent. Fourier transform infrared spectroscopy studies showed that the synthesis by an in situ process led to effective site‐selective interactions between the quinoid ring of the PANI and the multiwalled nanotubes, facilitating charge‐transfer processes between the two components. The morphological analysis indicated that the c‐MWNTs were well dispersed and isolated, and the tubes became crowded proportionally to the weight percentage of c‐MWNTs used in the composites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Circular dichroism and UV‐resonance Raman investigation of the temperature dependence of the conformations of linear and cyclic elastin
Authors: Ahmed Zeeshan , Scaffidi Jonathan P. , Asher Sanford A. 
Published: October 2008

AbstractWe used electronic circular dichroism (CD) and UV resonance Raman (UVRR) spectroscopy at 204 nm excitation to examine the temperature dependence of conformational changes in cyclic and linear elastin peptides. We utilize CD spectroscopy to study global conformation changes in elastin peptides, while UVRR is utilized to probe the local conformation and hydrogen bonding of Val and Pro peptide bonds. Our results indicate that at 20 °C cyclic elastin predominantly populates distorted β‐strand, β‐type II and β‐type III turn conformations. At 60 °C, the β‐type II turn population increases, while the distorted β‐strand population decreases. Linear elastin predominantly adopts distorted β‐strand and β‐type III turn conformations with some β‐type II turn population at 20 °C. Increasing temperature to 60 °C results in a small increase in the turn population. © 2008 Wiley Periodicals, Inc. Biopolymers 91: 52–60, 2009.This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Controlling cell position in complex heterotypic 3D microtissues by tissue fusion
Authors: Rago Adam P. , Dean Dylan M. , Morgan Jeffrey R. 
Published: October 2008

AbstractTissue fusion and cell sorting are processes fundamental to developmental biology with applications in tissue engineering. We have designed a fusion assay to investigate the factors governing the fusion of microtissues and the cell sorting that occurs after fusion. Normal human fibroblast (NHF) spheroids were self‐assembled and cultured for 1, 4, or 7 days, then combined in trough shaped recesses. Over a 24‐h period the spheroids fused to become a rod shaped microtissue and the kinetics and extent of fusion could be quantified by assessing rod contraction. By varying the amount of spheroid culture time prior to fusion (1–7 days), the rate of fusion, the coherence of the building units (as measured by fusion angle) and the steady state length of the structure could be easily controlled. Longer pre‐culture times for the spheroids resulted in slower fusion, less coherence and increased length of rod microtissues. The fusion kinetics and steady length of rods formed by smaller versus larger spheroids (∼100 vs. 300 µm diameter) were indistinguishable, even though smaller spheroids had twice the surface area and greater numbers of contacts between units. Both small and large spheroids were strongly influenced by spheroid pre‐culture time. Pre‐culture time could also be used to control cell sorting and cell position when combinations of NHFs and H35s, a rat hepatocyte cell line, were fused to form heterotypic microtissues. Control of fusion and cell position are important parameters for creating functional heterotypic microtissues as well as the use of microtissues as building units to create larger tissue structures. Biotechnol. Bioeng. 2009;102: 1231–1241. © 2008 Wiley Periodicals, Inc.