Electrochromic properties of heat-treated thin films of CeO2–TiO2–ZrO2 prepared by sol–gel route

CeO₂–TiO₂–ZrO₂ thin films were prepared using the sol–gel process and deposited on glass and ITO-coated glass substrates via dip-coating technique. The samples were heat treated between 100 and 500 °C. The heat treatment effects on the electrochromic performances of the films were determined by means of cyclic voltammetry measurements. The structural behavior of the film was characterized by atomic force microscopy and X-ray diffraction. Refractive index, extinction coefficient, and thickness of the films were determined in the 350–1000 nm wavelength, using nkd spectrophotometry analysis.Heat treatment temperature affects the electrochromic, optical, and structural properties of the film. The charge density of the samples increased from 8.8 to 14.8 mC/cm², with increasing heat-treatment temperatures from 100 to 500 °C. It was determined that the highest ratio between anodic and cathodic charge takes place with increase of temperature up to 500 °C.     

Measurement of MOSFET substrate dopant profile via inversionlayer-to-substrate capacitance

In this paper, a new method for extracting substrate dopant concentration profile of short-channel MOSFET's is presented. It is based on the measurement of the small-signal capacitance between the inversion layer and the substrate. The method achieves effective deep depletion through dc reverse bias on the inversion-to substrate junction and thus avoids the problems with transients associated with pulsed C-V of MOS capacitors. By using transistors of different drawn lengths the effect of lateral extension of drain and source junction depletion regions is also accounted for     

Behaviour of pyrite during hydrogenation of graphite at atmospheric pressure

The pyrite behaviour during hydrogenation of graphite is investigated. Kinetic experiments were carried out using thermogravimetry. The solid burn up residue was examined by SEM, and by X-Ray and electronic diffraction. The results show how graphite hydrogenation at temperatures lower than 1000 °C can be achieved in the presence of metallic iron obtained from pyrite. Pyrite, or its reduced form pyrrhotite, appears to have no catalytic behaviour during hydrogenation of graphite.     

Direct hydrogenation of carbons by isothermal microthermogravimetry at atmospheric pressure

The effect of hydrogen partial pressure on the hydrogenation rate of lignite char has been studied at pressures between 0.3 and 1 atm and temperatures between 820 and 940°C by thermogravimetry. The apparent order as a function of hydrogen pressure and the activation energy of this reaction have been determined. Under the experimental conditions investigated in this work, after gasification of about 70% of the lignite char, the hydrogenation rate decreases rapidly.     

Effects of the Cd:Zn:S molar ratio and heat treatment on the optical and photoluminescence properties of nanocrystalline CdZnS thin films

Nanocrystalline cadmium zinc sulfide thin films with different molar ratios were prepared by sol–gel dip-coating in a polyethyleneglycol matrix. After heat treatment in air at 250, 350 and 450 °C, the thin films were characterized by studying their structural, morphological, compositional, optical (linear and nonlinear) and photoluminescence (PL) properties. According to X-ray diffraction (XRD) results, the samples are polycrystalline with a hexagonal crystal structure and an average grain size of 12–18 nm. The surface morphology of the films was examined by scanning electron microscopy (SEM). The results show that the films consist of nanocrystalline grains included in clusters with uniform coverage over the substrate surface. To determine their chemical composition, X-ray photoelectron spectra (XPS) of composite films were measured. The transmittance and bandgap of the films increased with the Zn concentration and decreased with increasing annealing temperature. The refractive index of the films was measured and the related dispersion is discussed in terms of the Wemple–DiDomenico single oscillator model. The third-order nonlinear polarizability of the films was estimated using a semi-empirical relation based on the single oscillator model. The results show that the films are suitable as optical switches. PL spectra were recorded for an excitation wavelength of 210 nm. The emission intensity for the films varied with the Zn ratio and the annealing temperature and the behavior of different peaks is discussed.     

Shortest paths in simple polygons with polygon-meet constraints

We study a constrained version of the shortest path problem in simple polygons, in which the path must visit a given target polygon. We provide a worst-case optimal algorithm for this problem and also present a method to construct a subdivision of the simple polygon to efficiently answer queries to retrieve the shortest polygon-meeting paths from a single-source to the query point. The algorithms are linear, both in time and space, in terms of the complexity of the two polygons.     

Low Dissipation with Normalized Flux Surfaces in 2-Dimensional Coordinate for IR-T1 Tokamak Using Grad–Shafranov Equation Solution

Together with the problem of confinement, plasma–wall interactions present the major constraints toward a magnetic fusion reactor. The solutions of Grad–Shafranov equation (GSE) analytically can be used for theoretical studies of plasma equilibrium, transport and magneto-hydrodynamic stability. Here we introduce specific choices for source functions, kinetic pressure and poloidal plasma current, to be quadratic in poloidal magnetic flux and derive an analytical solution for GS equation. With applying this solution to IR-T1 tokamak, we have calculated the poloidal magnetic flux, toroidal current density and normalized pressure profiles for this tokamak. Toroidal and poloidal flows can considerably change the equilibrium parameters of tokamak. These effects on the equilibrium of tokamak plasmas are numerically investigated using a code FLOW. As a comparative approach to equilibrium problem, the code is used to model equilibrium of IR-T1 tokamak for case pure toroidal flow.     

Compositional Dependence of Optical and Structural Properties of Nanogranular Mixed ZrO2/ZnO/SnO2 Thin Film

Metallurgical and Materials Transactions A - A study on the optical properties and photoluminescence (PL) spectra of ternary oxide nanogranular thin films comprising Zr, Zn, and Sn revealed that...     

Extensive beta-glucuronidase activity in murine central nervous system after adenovirus-mediated gene transfer to brain

Mucopolysaccharidosis type VII (MPS VII), caused by beta-glucuronidase deficiency, is a classic lysosomal storage disease. In the central nervous system (CNS), there is widespread pathology with distention of vacuoles in neurons and glia. An approach to therapy for MPS VII would require extensive delivery of enzyme to the CNS and subsequent uptake by the affected cells. In this study we show that intrastriatal injection of recombinant adenovirus encoding beta-glucuronidase (Ad betagluc) to MPS VII or wild-type mice results in focal, intense beta-glucuronidase mRNA expression near the injection site. Further, histochemical staining for enzyme activity showed that beta-glucuronidase activity extended well beyond transduced cells. Activity was detected throughout the ipsilateral striatum as well as in the corpus callosum, ventricles, and bilateral neocortex. Similarly, after injection into the right lateral ventricle or cisterna magna, enzyme activity was present in the ependymal cells of the ventricles, in the subarachnoid spaces, and also in the underlying cortex (150-500 microm from ependyma). The distribution of enzyme was most extensive 21 days after gene transfer to normal mouse brain, with more than 50% of the hemisphere positive for beta-glucuronidase activity. Eighty-four days after adenovirus injection a substantial level of enzyme expression remained (>40% of hemisphere positive for beta-glucuronidase activity). Histological sections from striatum of beta-glucuronidase-deficient mice injected with Ad betagluc showed a marked reduction in the number of distended vacuoles in both neurons and glia, as compared with uninjected striatum. Importantly, correction was noted in both hemispheres. Our finding that a relatively small number of transduced cells produce enzyme that reaches a large proportion of the CNS has favorable implications in developing direct gene transfer therapies for lysosomal storage disorders.     

Influence of graded changes in vasomotor tone on the carotid arterial mechanics in live spontaneously hypertensive rats

1. The contribution of vasomotor tone to the increased stiffness of carotid arteries in living spontaneously hypertensive rats (SHR) is largely unknown. Whether a reduced vascular tone is associated with an increase or a decrease in arterial stiffness in vivo remains to be determined. The goal of the present investigation was to show that a decrease in vascular tone is associated with a decrease in arterial stiffness, independent of the structural composition of the arterial wall. 2. New high resolution echo-tracking techniques were used to evaluate pulsatile changes of carotid blood pressure and diameter following transient and graded changes of vasomotor tone produced by the dihydropyridine derivative, isradipine. Treatment for 8 weeks was given to groups of SHR rats either with a low (0.6 kg day-1) or a high (2.6 mg kg-1 day-1) dose. Another SHR group received an acute dose of 2.6 mg kg-1 day-1. Results were compared to those of placebo-treated Wystar-Kyoto (WKY) and SHR rats. Whatever the dosage, acute or chronic calcium blockade caused a decrease in blood pressure which was maximal 1 h after administration and disappeared after the 16th h. Carotid arterial thickness and the composition of the arterial wall was determined from histomorphometry. 3. In placebo-treated SHR, the inverse relationship relating blood pressure to carotid arterial distensibility was significantly shifted toward higher values of blood pressure compared to the curve of normotensive placebo-treated WKY rats. The curve of SHR receiving chronically a non antihypertensive (0.6 mg kg-1 day-1) isradipine dose prolonged that of placebo-treated SHR toward lower values of blood pressure, so that carotid distensibility was significantly higher than in WKY for the same diameter and blood pressure level (145 mmHg). With administration of a chronic antihypertensive dose (2.6 mg kg-1 day-1) causing a significant decrease in arterial function. Acute antihypertensive calcium blockade with a single isradipine dose (2.6 mg kg-1 day-1) caused a similar shift in the pressure-distensibility curve toward the WKY curve although the histomorphometric composition of the arterial wall differed significantly from that of chronically treated animals. 4. The study provides evidence that, in living SHR submitted to calcium blockade, (i) a low dose of isradipine causing no substantial antihypertensive effect is associated with a significant elevation of carotid arterial distensibility for the same pressure and diameter as normotensive controls, and (ii) an acute or chronic dose causing a substantial antihypertensive effect is associated with a transient shift of the SHR distensibility-pressure curve toward a physiological arterial function, increasing carotid distensibility for the same pressure and diameter as WKY controls. Since such findings were observed independently of the histomorphometric composition of the arterial wall, they imply that the transient decrease in arterial stiffness produced by calcium blockade should involve specific changes in the connections between arterial smooth muscle and extracellular matrix.