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SEM
Terms modified by SEM Selected AbstractsRelationship between breathing and cardiovascular function at rest: sex-related differencesACTA PHYSIOLOGICA, Issue 2 2010B. G. Wallin Abstract Aim:, To compare relationships at rest between breathing rate, levels of muscle sympathetic nerve activity, total peripheral resistance and cardiac output among young men and women. Methods:, Recordings were made of respiratory movements, sympathetic nerve activity (peroneal microneurography), intra-arterial blood pressure, electrocardiogram, cardiac output (open-circuit acetylene uptake technique) in 19 healthy men (age 27 ± 2 years, mean ± SEM) and 17 healthy women (age 25 ± 1 years). Total peripheral resistance and stroke volume were calculated. Four minutes epochs of data were analysed. Results:, Breathing rates and sympathetic activity were similar in men and women but compared to men, women had significantly lower blood pressures, cardiac output and stroke volume. In men breathing rate correlated positively with sympathetic activity (r = 0.58, P < 0.05) but not in women (r = 0.12, P > 0.05). Furthermore, in men, respiratory rate correlated positively with total peripheral resistance (r = 0.65, P < 0.05) and inversely with cardiac output (r = ,0.84, P < 0.05) and heart rate (r = ,0.60, P < 0.05) but there were no such relationships in women (P > 0.05 for all). Conclusions:, The positive relationship between breathing and sympathetic activity in men, and the inverse coupling of breathing to cardiac output and heart rate suggest that influences of respiration may be important not only for dynamic but also for ,tonic' cardiovascular function. The lack of relationships among these variables in women shows that there are fundamental differences in basic blood pressure regulation between the sexes. [source] Development of olfactory epithelium in the human fetus: Scanning electron microscopic observationsCONGENITAL ANOMALIES, Issue 3 2009Mitsuhiro Kimura ABSTRACT Aims:, Human olfactory epithelium becomes functional at birth, but prenatal development remains unclear. In the present study, we aimed to clarify the development of human olfactory epithelium using scanning electron microscopy (SEM). Methods:, The development of human olfactory epithelium was observed in 24 externally normal fetuses, which were formalin-fixed and long-preserved, with a crown-rump length (CRL) of 102,336 mm (gestational week 14,38). The olfactory mucosa in the superior wall of the nasal septum near the choana were dissected and observed under SEM. We examined the number of olfactory vesicles per unit area, diameter of olfactory vesicles, and number and length of cilia on olfactory vesicles. Results:, At circa (ca) CRL 100 mm (ca 14 weeks), olfactory epithelium displayed several olfactory vesicles with 1,2 short cilia per unit area. At ca CRL 150 mm (ca 18 weeks), olfactory vesicles were present in small clusters, and cilia were longer. At CRL lager than 225 mm (ca 26 weeks), olfactory vesicles became located separately from each other, while length and number of cilia per olfactory vesicle were further increased. Conclusion:, The present findings suggest that fetal olfactory epithelium becomes morphologically almost the same as that in adults in late gestation, much later than previously thought. [source] Morphological and immunohistochemical studies on cleft palates induced by 2,3,7,8-tetrachlorodibenzo- p -dioxin in miceCONGENITAL ANOMALIES, Issue 2 2008Kumiko Fujiwara ABSTRACT Morphological and immunohistological examinations were performed to reveal the mechanisms of cleft palate induction by 2,3,7,8-tetrachlorodibenzo- p -dioxin (TCDD). ICR strain mice 8,10 weeks of age were used in the study. TCDD was administered in olive oil on gestation day (GD) 12.5 with gastric tubes at 40 ,g/kg. From GD 13.5 to 16.5, palates were examined by scanning electron microscopy (SEM), hematoxyline,eosin (HE) staining, and immunohistochemical staining of FGFR1/2, TGF-,3, MSX1 and LHX8. In the control group, both of the palatal shelves began elevating on GD 14.0 and finished within 6 h. After the elevation, all of the shelves had completely fused with each other on GD 14.5. In the TCDD-treated group, palatal shelves elevated 1 day later than in the control group. However, all palates had elevated by GD 15.0. After the elevation, the shelves contacted each other and fused; however, they were separated on GD16.0. HE staining showed that medial edge epithelium (MEE) was thinner in the TCDD group than in the control group. MEE observed under a high magnification (×2500) exhibited filopodia-like filaments and the cells were bulged in the control group. In contrast, in the TCDD group, no filaments were observed and the cells were flat with unclear boundaries. Immunohistologically, there were no characteristic findings except for FGFR1. FGFR1 was not expressed in the TCDD group after the fusion phase (GD 14.5). TCDD induces many morphological and molecular changes to MEE cells and causes cleft palates. [source] Cobalt release from inexpensive jewellery: has the use of cobalt replaced nickel following regulatory intervention?CONTACT DERMATITIS, Issue 2 2010Jacob Pontoppidan Thyssen Background: Before the introduction of the EU Nickel Directive, concern was raised that manufacturers of jewellery might turn from the use of nickel to cobalt following the regulatory intervention on nickel exposure. Objectives: The aim was to study 354 consumer items using the cobalt spot test. Cobalt release was assessed to obtain a risk estimate of cobalt allergy and dermatitis in consumers who would wear the jewellery. Methods: The cobalt spot test was used to assess cobalt release from all items. Microstructural characterization was made using scanning electron microscope (SEM) and energy-dispersive spectroscopy (EDS). Results: Cobalt release was found in 4 (1.1%) of 354 items. All these had a dark appearance. SEM/EDS was performed on the four dark appearing items which showed tin,cobalt plating on these. Conclusions: This study showed that only a minority of inexpensive jewellery purchased in Denmark released cobalt when analysed with the cobalt spot test. As fashion trends fluctuate and we found cobalt release from dark appearing jewellery, cobalt release from consumer items should be monitored in the future. Industries may not be fully aware of the potential cobalt allergy problem. [source] Systemic nitric oxide clamping in normal humans guided by total peripheral resistanceACTA PHYSIOLOGICA, Issue 2 2010J. A. Simonsen Abstract Aim:, We wanted to stabilize the availability of nitric oxide (NO) at levels compatible with normal systemic haemodynamics to provide a model for studies of complex regulations in the absence of changes in NO levels. Methods:, Normal volunteers (23,28 years) were infused i.v. with the nitric oxide synthase (NOS) inhibitor NG -nitro- l -arginine methyl ester (l -NAME) at 0.5 mg kg,1 h,1. One hour later, the NO donor sodium nitroprusside (SNP) was co-infused in doses eliminating the haemodynamic effects of l -NAME. Haemodynamic measurements included blood pressure (MABP) and cardiac output (CO) by impedance cardiography. Results:,l -NAME increased MABP and total peripheral resistance (TPR, 1.02 ± 0.05 to 1.36 ± 0.07 mmHg s mL,1, mean ± SEM, P < 0.001). With SNP, TPR fell to a stable value slightly below control (0.92 ± 0.05 mmHg s mL,1, P < 0.05). CO decreased with l -NAME (5.8 ± 0.3 to 4.7 ± 0.3 L min,1, P < 0.01) and returned to control when SNP was added (6.0 ± 0.3 L min,1). A decrease in plasma noradrenaline (42%, P < 0.01) during l -NAME administration was completely reversed by SNP. Plasma renin activity decreased during l -NAME administration and returned towards normal after addition of SNP. In contrast, plasma aldosterone was increased by l -NAME and remained elevated. Conclusions:, Concomitant NOS inhibition and NO donor administration can be adjusted to maintain TPR at control level for hours. This approach may be useful in protocols in which stabilization of the peripheral supply of NO is required. However, the dissociation between renin and aldosterone secretion needs further investigation. [source] Transformation of a zinc inclusion complex to wurtzite ZnS microflowers under solvothermal conditionsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 9 2010Liwei Mi Abstract Wurtzite zinc sulfide (ZnS) microflowers were synthesized successfully by a convenient solvothermal route in ethylene glycol (EG) and ethylenediamine (EN) using thiourea and zinc inclusion complex as starting materials. The inclusion complex {[Zn(bipy)2(H2O)2](4-Cl-3-NH2 -C6H3SO3)2(bipy) (H2O)2}n was achieved by the reaction of zinc oxide (ZnO) and 4-Cl-3-NH2 -C6H3SO3 with the bridging ligand bipy under moderate conditions, in which bipy is 4,4,-bipyridine and 4-Cl-3-NH2C6H3SO3NH is 4-Chloro-3-aminobenzene sulfonic acid. The phase purity of bulk products was confirmed by powder X-ray diffraction and element analysis. The factors that might affect the purity of the ZnS product during the synthesis were discussed in detail. It was found that the products were significantly affected by the mixed solvents and the starting materials. X-ray single crystal diffraction, scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), and X-ray diffraction (XRD) were used to characterize the products. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Synthesis and tribological properties of laminated Ti3SiC2 crystalsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 8 2010Qiong Wu Abstract Laminated Ti3SiC2 crystals are prepared of Ti, Si, C and Al powders by the method of hot isostatic pressing with NaCl additive in argon at 1350 °C. The laminated morphology of Ti3SiC2 is presented through the SEM and TEM observations. The results of high resolution transmission electron microscope (HRTEM) and selected area electron diffraction (SAED) patterns combined, it can be seen that the layers are of Ti3SiC2 crystals. The growth mechanism of Ti3SiC2 crystals, controlled by two-dimensional nucleation, is also explained. The tribological properties of Ti3SiC2 crystals as additives in HVI500 base oil are investigated by a UMT-2 ball-on-plate friction and wear tester. The study shows that under determinate conditions, the friction coefficient of the base oil containing Ti3SiC2 crystals is lower than that of pure base oil, and it decreases with the increase of mass percent of Ti3SiC2 nanolayers when its proportion is lower than 5wt. %. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Growth of single-grain GdBa2Cu3O7-x superconductors by top seeded infiltration and growth techniqueCRYSTAL RESEARCH AND TECHNOLOGY, Issue 3 2010Guo-Zheng Li Abstract The top seeded infiltration and growth technique (TSIG) is an effective way for the preparation of bulk REBa2Cu3O7-x (RE-123, where RE denotes rare earth) with finely dispersed RE2BaCuO5 (RE-211) particles compared to the conventional melt growth (MG) method. The nucleation temperature and the ending growth temperature are the most important parameters need to be optimized during the preparation of RE-123 bulks by the TSIG process. In this paper, the effects of these parameters on the growth of single-grain GdBa2Cu3O7-x (GdBCO) superconductors have been investigated experimentally. It is found that the temperature for the growth of single-grain GdBCO is in the region between 1040 °C and 1015 °C. In addition, the relation between growth rate and supercooling has been investigated in detail. The combined techniques of SEM and EDS were used to study the microstructure of the samples grown at different temperatures. Based on this, a two-step slow cooling method during the crystallization process is proposed for the fabrication of RE-123 bulks. Finally, the single-grain GdBCO samples of the diameters 20 mm and 30 mm were fabricated successfully by the TSIG technique, with the slow-cooling process in the temperature window 1030 °C,1020 °C for 60 h and 100 h respectively. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Influence of the substrate temperature on the structural, optical, and electrical properties of tin selenide thin films deposited by thermal evaporation methodCRYSTAL RESEARCH AND TECHNOLOGY, Issue 1 2010N. Kumar Abstract Thin films of tin selenide (SnSe) were deposited on sodalime glass substrates, which were held at different temperatures in the range of 350-550 K, from the pulverized compound material using thermal evaporation method. The effect of substrate temperature (Ts) on the structural, morphological, optical, and electrical properties of the films were investigated using x-ray diffraction analysis (XRD), scanning electron microscopy (SEM), transmission measurements, and Hall-effect characterization techniques. The temperature dependence of the resistance of the films was also studied in the temperature range of 80-330 K. The XRD spectra and the SEM image analyses suggest that the polycrystalline thin films having uniform distribution of grains along the (111) diffraction plane was obtained at all Ts. With the increase of Ts the intensity of the diffraction peaks increased and well-resolved peaks at 550 K, substrate temperature, were obtained. The analysis of the data of the optical transmission spectra suggests that the films had energy band gap in the range of 1.38-1.18 eV. Hall-effect measurements revealed the resistivity of films in the range 112-20 , cm for films deposited at different Ts. The activation energy for films deposited at different Ts was in the range of 0.14 eV-0.28 eV as derived from the analysis of the data of low-temperature resistivity measurements. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Effect of annealing on the structural, electrical and optical properties of nanostructured TiO2 thin filmsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 9 2009S. Sankar Abstract Nanostructured titanium dioxide thin films were prepared using reactive pulsed laser ablation technique. Effects of annealing on the structural, morphological, electrical and optical properties are discussed. The structural, electrical and optical properties of TiO2 films are found to be sensitive to annealing temperature and are described with GIXRD, SEM, AFM, UV-Visible spectroscopy and electrical studies. X-ray diffraction studies showed that the as-deposited films were amorphous and at first changed to anatase and then to rutile phase with increase of annealing temperature. Optical constants of these films were derived from the transmission spectra and the refractive index dispersion of the films, subjected to annealing at different temperatures, is discussed in terms of the single oscillator-Wemple and Didomenico model. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Solvothermal production of CdS nanorods using polyvinylpyrrolidone as a templateCRYSTAL RESEARCH AND TECHNOLOGY, Issue 8 2009Titipun Thongtem Abstract CdS nanorods were solvothermally produced using Cd(NO3)2 and S powder in ethylenediamine containing different amounts of polyvinylpyrrolidone (PVP). The phase with hexagonal structure was detected using X-ray diffraction (XRD) and selected area electron diffraction (SAED). Their SAED patterns were in accordance with those of the simulations. Scanning and transmission electron microscopies (SEM and TEM) revealed the presence of CdS nanorods with their lengths influenced by different amounts of PVP. The nanorods were also characterized using high resolution TEM (HRTEM). They grew in the [001] direction normal to the (002) parallel crystallographic planes composing the nanorods. Raman spectra showed the 1LO (first harmonic) and 2LO (second harmonic) modes at the same wavenumbers although the products were produced under different conditions. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Characterization of pure and doped potassium hydrogen tartrate single crystals grown in silica gelCRYSTAL RESEARCH AND TECHNOLOGY, Issue 5 2009I. Quasim Abstract Growth of pure-, sodium- and lithium- doped potassium hydrogen tartrate single crystals by gel technique is reported. Growth conditions conducive for the growth of single crystals are worked out. The crystals are characterized by using powder XRD, SEM, FTIR, AES, EDAX, CH analysis and thermoanalytical techniques. The stoichiometric composition for the grown crystals are established as KHC4H4O6.H2O, (K)0.98(Na)0.02.H2O and (K)0.94(Li)0.06HC4H4O6.H2O. Doping of sodium and lithium in the pure potassium hydrogen tartrate single crystals is found to influence the size, perfection, morphology, crystal structure and the thermal stability of crystals. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Characterization of dislocation structures in copper single crystals using electron channelling contrast technique in SEMCRYSTAL RESEARCH AND TECHNOLOGY, Issue 3 2009Xiao-Wu Li Abstract The dislocation structures induced by low-plastic-strain-amplitude cyclic deformation of [111] multiple-slip-oriented Cu single crystals were investigated using electron channelling contrast (ECC) technique in scanning electron microscopy (SEM). At a low plastic strain amplitude ,pl of 8.8 × 10,5, the saturated dislocation structure is mainly composed of labyrinth-like vein structure (or irregular labyrinths), and the cyclic hardening behavior at such a low ,pl is interpreted as being the result of dislocation multiplication by a Frank-Read mechanism. As ,pl increases to 4.0 × 10,4, the unsaturated dislocation structure exhibits two kinds of distinctive configurations, i.e., dislocation walls and misoriented cells. Interestingly, these misoriented dislocation cells are strictly aligned along the primary slip plane (111), constituting a unique persistent slip band (PSB) structure. Here, these cells are thus called PSB cells. In addition, there is a locally distinctive region comprising some cells having a recrystallization-like feature in the whole structure of PSB cells. The formation of the structure of PSB cells is discussed. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Low temperature hydrothermal growth and optical properties of ZnO nanorodsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 1 2009J. H. Yang Abstract Well-faceted hexagonal ZnO nanorods have been synthesized by a simple hydrothermal method at relative low temperature (90°C) without any catalysts or templates. Zinc oxide (ZnO) nanorods were grown in an aqueous solution that contained Zinc chloride (ZnCl2, Aldrich, purity 98%) and ammonia (25%). Most of the ZnO nanorods show the perfect hexagonal cross section and well-faceted top and side surfaces. The diameter of ZnO nanorods decreased with the reaction time prolonging. The samples have been characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) measurement. XRD pattern confirmed that the as-prepared ZnO was the single-phase wurtzite structure formation. SEM results showed that the samples were rod textures. The surface-related optical properties have been investigated by photoluminescence (PL) spectrum and Raman spectrum. Photoluminescence measurements showed each spectrum consists of a weak band ultraviolet (UV) band and a relatively broad visible light emission peak for the samples grown at different time. It has been found that the green emission in Raman measurement may be related to surface states. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Growth and characterization of strontium tartrate pentahydrate crystalsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 10 2008A. Firdous Abstract Silica gel impregnated with L-tartaric acid and using strontium nitrate as the second reactant leads to the growth of well faceted strontium tartrate pentahydrate single crystals. The morphological developmen and internal cell dimensions are observed to be different from the ones reported in the literature for strontium tartrate trihydrate crystals. The crystals are characterized using XRD, CH analysis, SEM, FTIR spectroscopy and thermoanalytical techniques. The crystals are observed to be thermally stable upto about 105°C but thereafter start decomposing and ejecting water of hydration at various stages, finally reducing to strontium oxide. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Characterization of reactive DC magnetron sputtered TiAlN thin filmsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 10 2008B. Subramanian Abstract Thin films of about 1,m Titanium Aluminum Nitride (TiAlN) were deposited onto mild steel substrates by reactive direct current (DC) magnetron sputtering using a target consisting of equal segments of titanium and aluminum. X-ray diffraction (XRD) analysis showed that the TiAlN phase had preferred orientations along 111 and 200 with the face-centered cubic structure. Scanning Electron Microscope (SEM) and Atomic Force Microscope (AFM) analyses indicated that the films were uniform and compact. Photoluminescence (PL) spectra reveal that TiAlN thin films are of good optical quality. Laser Raman studies revealed the presence of characteristic peaks of TiAlN at 312.5, 675, and 1187.5 cm,1. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Studies on electrical conduction behavior of La1-3xCaxBaxSrxMnO3 synthesized by chemical routeCRYSTAL RESEARCH AND TECHNOLOGY, Issue 3 2008K. D. Mandal Abstract In the manganite La1-xMxMnO3 (M = Ca, Ba, Sr) the doping concentration introduces a mixed valency (Mn3+, Mn4+) which governs the magnetic and electrical properties of the compound. The perovskite oxides La1-3xCaxBaxSrxMnO3 (x = 0.00, 0.05, 0.10) were prepared by chemical method. Single-phase formation is confirmed by XRD studies. The electrical behavior of compositions with x = 0.00, 0.05 and 0.10 in the system La1-3xCaxBaxSrxMnO3 was studied in the temperature range 300-420 K. It is observed that conductivity decreases with increasing temperature as well as dopants concentration. Metallic behavior of these compositions decreases with increasing dopants concentration (x). The microstructures of these samples have been characterized using scanning electron microscopy (SEM). (© 2007 WILEY -VCH Verlag GmbH & Co. KGaA, Weinheim) [source] PSSS-controlled synthesis of CaCO3 superstructuresCRYSTAL RESEARCH AND TECHNOLOGY, Issue 9 2007Hua Tang Abstract Complex CaCO3 superstructure can be easily synthesized by using poly (sodium 4-styrenesulfonate) (PSSS) as a structure directing agent to direct the controlled precipitation of calcium carbonate from aqueous solution. The products were characterized by scanning electron microscopy (SEM), and powder X-ray diffraction (XRD) analysis. The results revealed that the morphology of the products changed significantly with the increasing of the concentration of PSSS in solution, from rhombohedral particles to plate-packed aggregates to spheres with smooth surface, to sponge-like spheres and finally to complex spherical superstructure consisted of plate-like sub-units. We hypothesize that the observed sequential changes in morphology of CaCO3 particles with added PSSS concentration may be due to the influence of PSSS on nucleation, growth and aggregation of CaCO3 crystals. The formation mechanisms of CaCO3 crystals with different morphologies were discussed. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Photostimulated changes of properties of CdTe filmsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 8 2007T. D. Dzhafarov Abstract The effect of illumination during the close-spaced sublimation (CSS) growth on composition, structural, electrical, optical and photovoltaic properties of CdTe films and CdTe/CdS solar cells were investigated. Data on comparative study by using X-ray diffraction (XRD), scanning electron microscopy (SEM), absorption spectra and conductivity-temperature measurements of CdTe films prepared by CSS method in dark (CSSD) and under illumination (CSSI) were presented. It is shown that the growth rate and the grain size of CdTe films grown under illumination is higher (by factor about of 1.5 and 3 respectively) than those for films prepared without illumination. The energy band gap of CdTe films fabricated by both technology, determined from absorption spectra, is same (about of 1.50 eV), however conductivity of the CdTe films produced by CSSI is considerably greater (by factor of 107) than that of films prepared by CSSD. The photovoltaic parameters of pCdTe/nCdS solar cells fabricated by photostimulated CSSI technology (Jsc = 28 mA/cm2, Voc =0.63 V) are considerably larger than those for cells prepared by CSSD method (Jsc = 22 mA/cm2, Voc = 0.52 V). A mechanism of photostimulated changes of properties of CdTe films and improvement of photovoltaic parameters of CdTe/CdS solar cells is suggested. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] XRD, thermal, FTIR and SEM studies on gel grown ,-glycine crystalsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 1 2007E. Ramachandran Abstract Glycine is the smallest among amino acids. The polymorphs, ,- and ,-forms of glycine were crystallized in silica gel by reduction of solubility method. The grown crystals were characterized by single crystal X-ray diffraction studies and density determination. Fourier transform infrared spectroscopic studies and thermogravimetric analysis of ,-glycine were also conducted. Morphological and scanning electron microscopic (SEM) studies were also made and compared with the crystal packing. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Gel growth and characterization of , -DL-methionineCRYSTAL RESEARCH AND TECHNOLOGY, Issue 4 2006E. Ramachandran Abstract DL-Methionine [C5H11NO2S] is one of the essential amino acids in humans. It has two crystalline forms, viz., ,- and ,- methionine. In the present study, , - form is crystallized in silica gel; under suitable pH conditions by single diffusion method. The grown crystals were characterized by density measurement and single crystal X-ray diffraction. Fourier transform infrared (FTIR) spectroscopic studies, thermal analysis and scanning electron microscopic (SEM) studies were also made as part of the structural studies. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Optimization of Cr8O21 targets for Pulsed Laser DepositionCRYSTAL RESEARCH AND TECHNOLOGY, Issue 12 2005L. Tortet Abstract This work describes the preparation of Cr8O21 pellets with optimised mass density to be used as targets for Pulsed Laser Deposition (PLD) of chromium dioxide thin films. Cr8O21 is synthesised by thermal decomposition of CrO3, at 270 °C. An attempt to reduce the grain size of the Cr8O21 powder to the nanometer scale has been made in order to increase the density of the pressed and sintered pellets serving as targets. The morphology of those starting fine powders as well as of targets (before and after laser ablation) and the corresponding thin films were characterized and studied using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Raman spectroscopy. The composition of the films is a mixture of crystallised Cr2O3 and amorphous CrO2. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Growth of lead bromide polycrystalline filmsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 10 2004M. Giles Abstract Lead bromide polycrystalline films were grown by the physical vapor deposition method (PVD). Glass 1,x1, in size, uncoated, and coated with Indium Tin Oxide (ITO), was used as substrate and rear contact. The starting material was evaporated at temperatures from 395°C to 530°C under high vacuum atmosphere (6 x 10 -3 Pa) and during 8 days. The substrate temperature was prefixed from 190°C to 220°C. Film thickness yielded values from 40 to 90 ,m. Optical microscopy and scanning electron microscopy (SEM) were performed on the films. Grain size resulted to be from 1.0 to 3.5 ,m. SEM and X-ray diffraction indicate that films grow with a preferred orientation with the (0 0 l) planes parallel to the substrate. The Texture Coefficient (TC) related to the plane (0 0 6) was 7.3. Resistivity values in the order of 1012 ,cm were obtained for the oriented samples, but a strong polarization indicates severe charge transport problems in the films. Film properties were correlated with the growth temperature and with previous results for films of other halides. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Growth of bismuth tri-iodide platelets by the physical vapor deposition methodCRYSTAL RESEARCH AND TECHNOLOGY, Issue 10 2004A. Cuña Abstract The work reports the growth of single BI3 crystals with platelets habit. Platelets were grown by physical vapor deposition (PVD) in a high vacuum atmosphere and with argon, polymer or iodine as additives. Crystals grew in the zone of maximum temperature gradient, perpendicular to the ampoule wall. Crystals grown with argon as additive show a very shining surface, have hexagonal (0 0 l) faces, sizes up to 20 x 10 mm2 and thicknesses up to 100 ,m. They were characterized by optical microscopy and scanning electron microscopy (SEM). Dendritic-like structures were found to be their main surface defect. SEM indicates that they grow from the staking of hexagonal unities. Electrical properties of the crystals grown under different growth conditions were determined. Resistivities up to 2 x 1012 ,cm (the best reported value for monocrystals of this material) were obtained. X-ray response was measured by irradiation of the platelets with a 241Am source of 3.5 mR/h. A comparison of results according to the growth conditions was made. Properties of the crystals grown by this method are compared with the ones measured for others previously grown from the melt. Also, results for bismuth tri-iodide platelets are compared with the ones obtained for mercuric and lead iodide platelets. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The effect of alloying elements on the crystallization behaviour and on the properties of galvanized coatingsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 1 2004G. Vourlias Abstract The influence of the alloying elements on the interface reactions of zinc coatings during the galvanization process was examined. These reactions affect the crystallization and the structure and properties of the outer layer of the coatings. Depending on the type and concentration of the alloying additions in the galvanizing bath differences were induced in the crystallization process of the Fe-Zn phases. It was found that both the concentration and the distribution of the alloying elements played an important role in the growth of the phases. The formation of the phases and the distribution of the alloying elements in the coatings were determined using X-Ray diffraction (XRD) and Scanning Electron Microscopy (SEM) associated with an Energy Dispersive X-Ray Spectroscopy (EDS) analysis. Finally the behaviour of the galvanized coatings was examined under accelerated salt spray corrosion conditions. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Exercise is the primary factor associated with Hsp70 induction in muscle of treadmill running ratsACTA PHYSIOLOGICA, Issue 4 2006E. G. Noble Abstract Aim:, The cytoprotective, inducible stress protein, Hsp70, increases in muscles of rodents subjected to strenuous treadmill running. Most treadmill running protocols employ negative reinforcement to encourage animals to exercise. As these stimuli may themselves activate stress responses, the present investigation was conducted to determine their contribution to the exercise-induced expression of Hsp70. Methods:, Twenty-one male Sprague,Dawley rats were randomly divided into three equal groups including an exercise group (EX), which ran on a treadmill at 30 m min,1 for 60 min; a stimulation group (STIM), which was not allowed to run, but was stimulated with compressed air and mild electric shock concurrently with their exercising cohort; and a control group (CON), which was housed in the treadmill room during the exercise period. Animals were killed 24 h post-experiment and hearts (H), soleii (SOL) and white gastrocnemii (WG) were harvested and analysed for Hsp70 content (mean% ± SEM of standard). Results:, Significant increases in Hsp70 (as a % of standard) were noted in H and WG (H = 77.4 ± 8.5; WG = 93.9 ± 18.4) of EX but not in STIM (H = 32.5 ± 4.6; WG = 32.0 ± 3.4) or CON (H = 20.5 ± 3.7; WG = 32.4 ± 7.4). In SOL, Hsp70 expression in EX (126.7 ± 6.2) was different from STIM (98.3 ± 10.9) only. This occurred, despite the fact that all groups were exposed to a stressful environment and exhibited elevated (P < 0.001) temperatures (EX ,41.2 ± 0.1 °C > STIM ,40.5 ± 0.2 °C > CON ,39.0 ± 0.1 °C) indicative of a general stress response. Conclusions:, These data suggest that exercise per se, rather than environmental conditions or noxious stimuli, are responsible for the induction of Hsp70 in rat muscle during treadmill running. [source] Small Wonder: Using SEM Images to Exhibit the "Small Stuff"CURATOR THE MUSEUM JOURNAL, Issue 3 2009Alwynne B. Beaudoin In 2007, the Royal Alberta Museum held an exhibition of 28 SEM (scanning electron microscope) images of seeds and other subfossil macroremains, which were shown in a fine-art format. The exhibition was prepared by a museum team using images derived from in-house curatorial research work. This paper describes the exhibition components and reports on an attempt to engage the visitors more closely with the images by asking them to suggest identifications for some "mystery" specimens. [source] Adenosine induces prolonged anti-,-adrenergic effects in guinea-pig papillary muscleACTA PHYSIOLOGICA, Issue 1 2002L. ARVOLA ABSTRACT A sustained anti- , -adrenergic effect of adenosine has been reported. This study was initiated to investigate this topic and especially elucidate the role of protein kinase C (PKC). Contractile force amplitude and action potential duration at 90% repolarization (APD90) were measured in guinea-pig papillary muscles before and after 5 min challenge with 5 nm isoproterenol. Protocols contained 30 min exposure to the test agents adenosine 33 ,m (ado), adenosine + PKC-inhibitor bisindolylmaleimide 20 nM (ado + BIM), PKC-activator 1,2-dioctanoyl-sn-glycerol 10 ,m (DOG) and , -agonist phenylephrine 5 ,m (phe). Isoproterenol was given at the end of test exposure and after 15 min washout. Results are mean ± SEM of percentage-change, P , 0.05 considered significant and labelled *. The first isoproterenol challenge significantly increased contractile force (27 ± 7%*) in the control group. Responses in the test groups were 2 ± 4 (ado), 1 ± 5 (ado + BIM), 14 ± 4* (DOG), 0 ± 2% (phe). After washout of adenosine, DOG and phenylephrine, isoproterenol induced 3 ± 8 (ado), 23 ± 5* (ado + BIM), 13 ± 5* (DOG), 15 ± 7% (phe) increase in test groups compared with 22 ± 5%* increase in contractile force in the control group. After 45 min washout of adenosine the inotropic response was still significantly reduced compared with control (29 ± 4 vs. 79 ± 8%*). Isoproterenol stimulation shortened APD90 in controls at both time points (5 ± 1%* and 4 ± 1%*), with no significant shortening in test groups. Adenosine induces sustained anti- , -adrenergic effects on contractile force as well as APD90. A role for PKC in signal transduction is supported with respect to contractile force. [source] Supply Management Under High Goal Incongruence: An Empirical Examination of Disintermediation in the Aerospace Supply ChainDECISION SCIENCES, Issue 3 2008Christian L. Rossetti ABSTRACT Aftermarket sales and profits are becoming an increasingly important part of an original equipment manufacturer's (OEM) business model. Because replacement parts often do not require further manufacturing, OEMs act as intermediaries in the aftermarket. As with any intermediary, the OEM must concern itself with suppliers disintermediating its supply chain selling replacement parts directly to the OEM's customers. We frame supply chain disintermediation (SCD) as a principal,agent contracting problem between an OEM buyer and a supplier. Hypotheses relate contract conditions, goal incongruence, supplier capabilities and contract enforcement to SCD. The data are collected from the aerospace industry using a multimethod study, combining an Internet-based survey with archival data. Causal modeling with structural equation modeling (SEM) shows general support for the hypotheses. Particularly, SCD is positively related to buyer,supplier goal incongruence. The agency model offers insights that differ from previous transaction-cost-based models of buyer,supplier relationships. OEM buyers with a lucrative aftermarket should consider aligning goals through incentives rather than relying entirely on economic hostages associated with specific assets. [source] Forearm vascular and neuroendocrine responses to graded water immersion in humansACTA PHYSIOLOGICA, Issue 2 2000Gabrielsen The hypothesis that graded expansion of central blood volume by water immersion to the xiphoid process and neck would elicit a graded decrease in forearm vascular resistance was tested. Central venous pressure increased (P < 0.05) by 4.2 ± 0.4 mmHg (mean ± SEM) during xiphoid immersion and by 10.4 ± 0.5 mmHg during neck immersion. Plasma noradrenaline was gradually suppressed (P < 0.05) by 62 ± 8 and 104 ± 11 pg mL,1 during xiphoid and neck immersion, respectively, indicating a graded suppression of sympathetic nervous activity. Plasma concentrations of arginine vasopressin were suppressed by 1.5 ± 0.5 pg mL,1 (P < 0.05) during xiphoid immersion and by 2.0 ± 0.5 pg mL,1 during neck immersion (P < 0.05 vs. xiphoid immersion). Forearm subcutaneous vascular resistance decreased to the same extent by 26 ± 9 and 28 ± 4% (P < 0.05), respectively, during both immersion procedures, whereas forearm skeletal muscle vascular resistance declined only during neck immersion by 27 ± 6% (P < 0.05). In conclusion, graded central blood volume expansion initiated a graded decrease in sympathetic nervous activity and AVP-release. Changes in forearm subcutaneous vascular resistance, however, were not related to the gradual withdrawal of the sympathetic and neuroendocrine vasoconstrictor activity. Forearm skeletal muscle vasodilatation exhibited a more graded response with a detectable decrease only during immersion to the neck. Therefore, the forearm subcutaneous vasodilator response reaches saturation at a lower degree of central volume expansion than that of forearm skeletal muscle. [source] | |||||||||||||||||||||||||||||||||||||||||||||||||