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Characteristic Morphology (characteristic + morphology)
Selected AbstractsMelt Crystallization and Morphology of Poly(p -phenylene sulfide) under High PressureMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 4 2007Jun Lu Abstract The high-pressure melt-crystallization behaviors of poly(p -phenylene sulfide) (PPS) were investigated using WAXD, DSC, TEM and SEM. PPS extended-chain crystals with c -axis thickness exceeding 4.5 µm were formed at high pressure. The DSC results showed that the melting temperature and melting enthalpy of high-pressure crystallized PPS samples were up to 327.53,°C and 94.96 J,·,g,1, respectively, which were higher than the values of ideal PPS perfect crystals used by some researchers, and the melting enthalpy of the samples fluctuated regularly during the thickening growth of the PPS crystals. Other characteristic morphologies obtained at high pressure, i.e. spherulites and rod-like crystals, were also presented with the SEM measurements. [source] Semi-IPN asymmetric membranes based on polyether imide (ULTEM) and polyethylene glycol diacrylate for gaseous separationJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2008Sundar Saimani Abstract Semi-interpenetrating polymer networks (semi-IPN) formed with commercial polyether imide (ULTEM®, PEI) and poly (ethylene glycol) diacrylate (PEGDA) were used to make asymmetric membranes. The effect of increasing amount of PEGDA on the bulk and the gas separation properties of semi-IPN membranes were studied. The formation of IPNs was confirmed by Fourier Transform Infra Red (FT-IR) spectroscopy. The 5% weight loss temperature decreased and the percent weight loss of the first step increased with increase in the PEGDA content, which indicated the incorporation of more poly (ethylene glycol) (PEG) segments to the semi-IPNs. The microscopic experiments revealed the change in morphology with change in PEGDA content. The Scanning electron micrographs exhibited typical finger-like voids in the sub layer, which is characteristic morphology of asymmetric membranes. The increase in PEGDA content up to 5.7 wt % increased the CO2/N2 selectivity of the semi-IPN after which the selectivity decreased and permeance increased. Although, the increase in the polar poly (ethylene glycol) molecules is expected to render better CO2 selectivity, the performance of the membrane was found to decrease as PEGDA content exceeded 5.7% for the given ratio. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Constructive modification of conducting polyaniline characteristics in unusual proportion through nanomaterial blend formation with the neutral polymer poly(vinyl pyrrolidone)JOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2007E. Subramanian Abstract The present work reports an investigation on the modification of conducting polyaniline (PANI) characteristics favorably on blending with the neutral polymer, poly(vinyl pyrrolidone) (PVP) in a systematic variation of their molar ratios (aniline : PVP = 4 : 1, 2 : 1, 1 : 1, 1 : 2, and 1 : 3). Prepared by precipitation technique by conventional in situ chemical oxidative polymerization with ammonium peroxodisulfate in aqueous H2SO4 medium (pH 1.0), these materials have nanometer sizes (, 50,200 nm) and, depending on the molar ratios, exhibit a distinct deviation in physicochemical characteristics from those of pristine PANI prepared in the identical condition. A gradual trend in characteristics is noticed in first three PANI,PVP blends, while an abnormal hike in conductivity, unusual spectral features in IR and UV,vis, hardened nature, and induction of characteristic morphology, crystallinity, and thermal stability are associated with the last two blends that have excess PVP. Thus a division of two sets of nanoblends, one set with less or equal content of PVP and another with excess of PVP, emerges. Evidently, PVP has a tuning effect on PANI through its dopant, supporting matrix and interpenetrating steric stabilizer acts in proportion quite unusual to its neutral nature. The study altogether brings to light a simple way of modification of PANI characteristics by conventional method of blend synthesis. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source] 2,-Deoxyadenosine causes apoptotic cell death in a human colon carcinoma cell lineJOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, Issue 6 2003Michela Giannecchini Abstract The combination of 2,-deoxyadenosine and 2,-deoxycoformycin is toxic for the human colon carcinoma cell line LoVo. In this study we investigated the mode of action of the two compounds and have found that they promote apoptosis. The examination by fluorescence microscopy of the cells treated with the combination revealed the characteristic morphology associated with apoptosis, such as chromatin condensation and nuclear fragmentation. The occurrence of apoptosis was also confirmed by the release of cytochrome c and the proteolytic processing of procaspase-3 in cells subjected to the treatment. To exert its triggering action on the apoptotic process, 2,-deoxyadenosine enters the cells through an equilibrative nitrobenzyl-thioinosine-insensitive carrier, and must be phosphorylated by intracellular kinases. Indeed, in the present work we demonstrate by analysis of the intracellular metabolic derivatives of 2,-deoxyadenosine that, as suggested by our previous findings, in the incubation performed with 2,-deoxyadenosine and 2,-deoxycoformycin, an appreciable amount of dATP was formed. Conversely, when also an inhibitor of adenosine kinase was added to the incubation mixture, dATP was not formed, and the toxic and apoptotic effect of the combination was completely reverted. © 2003 Wiley Periodicals, Inc. J Biochem Mol Toxicol 17:329,337, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.10095 [source] Morphologies and projections of defined classes of neurons in the submucosa of the guinea-pig small intestineTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 2 2003John B. Furness Abstract Four types of neurons have previously been identified by neurochemical markers in the submucosal ganglia of the guinea-pig small intestine, and functional roles have been ascribed to each type. However, morphological differences among the classes have not been determined, and there is only partial information about their projections within the submucosa. In the present work, we used intracellular microelectrodes to fill neurons of each type with biocytin, which was then converted to a permanent dye, so that the shapes of the neurons could be determined and their projections within the submucosa could be followed. Cell bodies of noncholinergic secretomotor/ vasodilator neurons had Dogiel type I morphology. These neurons, which are vasoactive intestinal peptide immunoreactive, had single axons that ran through many ganglia without providing terminals around other neurons. Cholinergic secretomotor neurons with neuropeptide Y immunoreactivity had Stach type IV morphology, and cholinergic secretomotor/vasodilator neurons had stellate cell bodies. The axons of these two types ran short distances in the plexus and did not innervate other submucosal neurons. Neurons of the fourth type, intrinsic primary afferent neurons, had cell bodies with Dogiel type II morphology and their processes supplied networks of varicose processes around other nerve cells. It is concluded that each functionally defined type of submucosal neuron has a characteristic morphology and that intrinsic primary afferent neurons synapse with secretomotor neurons to form monosynaptic secretomotor reflex circuits. Anat Rec Part A 272A:475,483, 2003. © 2003 Wiley-Liss, Inc. [source] Time-course and characteristic morphology of retinal changes following combination of verteporfin therapy and intravitreal triamcinolone in neovascular age-related macular degenerationACTA OPHTHALMOLOGICA, Issue 2 2010Shilla Lie Abstract. Purpose:, To identify characteristic morphological changes of the retina over time and the association with visual function after combined photodynamic therapy (PDT) and intravitreal triamcinolone (IVTA). Methods:, In this retrospective study, 40 patients (40 eyes) were treated with PDT and same-day IVTA. Optical coherence tomography (OCT), fluorescein angiography (FA) and evaluation of distance visual acuity (VA) were performed. The anatomical changes within intra- and subretinal compartments and their detailed analysis and grading were the main outcome measures. Results:, Intraretinal fluid (IRF) and subretinal fluid (SRF) by OCT decreased until 3 months (p < 0.01). At month 3, intraretinal cystoid spaces (ICS) had resolved or decreased in 84% of eyes, SRF in 58% and pigment epithelial detachment (PED) in 50%. Mean best-corrected VA (BCVA) improved significantly at month 1 (p < 0.01). Mean central retinal thickness (CRT) increased from 334 ,m at baseline to 439 ,m at day 1 (p = 0.03) before decreasing to 286 ,m at day 7 (p = 0.06), 233 ,m at month 1 (p = 0.001) and 255 ,m at month 3 (p = 0.001). Conclusion:, Combined verteporfin/IVTA therapy induces distinct time-related effects on the retina within the different intra- and subretinal compartments. [source] | ||||||||||