Hot Corrosion Behavior of YSZ and CaZrO<Subscript>3</Subscript>/YSZ Composite Thermal Barrier Coatings in Contact with 50V<Subscript>2</Subscript>O<Subscript>5</Subscript> + 50Na<Subscript>2</Subscript>SO<Subscript>4</Subscript> Salts

A novel thermal barrier coating system was formulated to resist hot corrosion environments. In this coating system, 5% CaZrO₃ was added to conventional yttria-stabilized zirconia (YSZ). The above composite coating system was compared with the standard YSZ system in the presence of a mixture of 50% Na₂SO₄ and 50% V₂O₅ at 950 °C. The results demonstrated that the lifetime of the CaZrO₃-added composite system in this highly hostile environment was longer compared with the standard YSZ system. This is due to the fact that the preferential reaction of NaVO₃ shifted from yttria to calcia, forming CaV₂O₄ instead of YVO₄. The preferential reactions are discussed in terms of free energy changes and acid–base theory of molten salts with ceramic oxides. Furthermore, calculations of lattice distortion also proved that the CaZrO₃-added composite system demonstrated less distortion, thus increasing the overall lifetime of the coating system.     

Experimental study of conjugate heat transfer within a bottom heated vertical concentric cylindrical enclosure

In this research work an experimental study of conjugate heat transfer within an air filled bottom-heated vertical enclosure is conducted. The enclosure consists of two concentric cylinders with inner cylinder being shorter and open at the top. The study is important with respect to the centrifuge machine used in the process industry. Eighteen different experiments are performed by varying the bottom disc central temperature between 353 and 433 K, using three different materials (aluminum, mild steel and stainless steel) of the inner cylinder and two different diameter outer cylinders of mild steel. This study unfolds the temperature, material and geometric effects of bottom disc, inner cylinder and outer cylinder respectively on thermal convection in the enclosure. Generally, a uniform temperature is required in such enclosures. A more uniform axial and radial temperature is observed in the enclosure by using aluminum inner cylinder within a temperature range of 353–433 K of the bottom disc and using two different diameter outer cylinders. It is observed that the maximum temperature in the enclosure is lowest for aluminum inner cylinder and higher for mild steel and highest for stainless steel. The heat balance and non-dimensional analysis of the enclosure are carried out and discussed critically.     

Hydrogen Balmer-β and Balmer-γ emission profiles in an abnormal glow region of hydrogen plasma

Emission spectroscopy measurements of Balmer-β and Balmer-γ line profiles are carried out to study their line shapes and line intensities as a function of discharge parameters such as fill pressure (3-7 mbar) and input power (200-400 W). A technique based on determining the relative intensities of neutral atomic hydrogen emission lines is used to evaluate the electron temperature, whereas the electron density is extracted from the Stark broadening (FWHM) of the H_β emission profile. It is found that both the emission intensity and the broadening of the Balmer-β and Balmer-γ lines exhibit significant dependence on the fill pressure in the same manner. However, both the emission intensity and broadening of the H_β line exhibit a weak dependence on input power in contrast to the H_γ emission line. Based on optical measurements reported here, plasma discharge parameters can be selected to optimize the electron temperature and density.     

Cephalic tetanus: demonstration of a dual lesion

A clinical and electrophysiological study of 15 cases of cephalic tetanus is reported. This condition is a form of local tetanus which commonly follows an injury to the face or head. It is characterised by muscle paralysis which is maximal close to the site of injury, while spasm is evident at mroe distant sites. As muscle paralysis improves with time it is succeeded by spasm. It is argued that paralysis is due to high local concentrations of toxin in the brainstem while lesser concentrations cause spasm by abolishing inhibition. Electrophysiological studies indicate that paralysis is of lower motor neurone type with denervation potentials, hyperirritability, loss of motor units, and marginally increased distal latencies being the features recorded.     

The preparation of cadmium phosphate and cadmium zinc phosphate glasses and their electrical and optical properties

The preparation of a range of glasses based on CdO-P₂O₅ and CdO-ZnO-P₂O₅ is described and data are reported on density, electrical conductivity and optical absorption. The electrical conduction is electronic rather than ionic and is due to hopping between localized states. The optical absorption is due to forbidden indirect electronic transitions.     

Electrocatalytic reduction of hydrogen peroxide at a stationary pyrolytic graphite electrode surface in the presence of cytochrome c peroxidase: a description based on a microelectrode array model for adsorbed enzyme molecules

Electrochemical reduction of H2O2 at pyrolytic graphite disc electrodes of radius 2.5 mm occurs at readily accessible potentials (600 mV versus the standard hydrogen electrode) in the presence of yeast cytochrome c peroxidase. Introduction of the enzyme into the electrolyte solution initiates large changes in the ellipsometric angles measured for the electrode-solution interface, consistent with time-dependent enzyme adsorption. This process may be correlated with changes in electrochemical activity. Over the same time course, linear-sweep voltammograms are characterized by a transition from a sigmoidal to a peak-type waveform. It is proposed that the time-dependent behaviour may be rationalized by use of a microscopic model for substrate mass transport, in which the two-electron reduction of peroxide occurs at electrocatalytic sites consisting of adsorbed enzyme molecules. A voltammetric theory based on treating the adsorbed redox enzymes as an expanding array of microelectrodes is in excellent agreement with experiment.     

Muon-spin-relaxation studies on the heavy-fermion system with non-Fermi-liquid behavior CeCu5.9Au0.1

A patient with a history of pelvic radiation therapy for seminoma presented with a prostatic tumor, which appeared predominantly of high signal intensity on T2-weighted magnetic resonance images; low-signal-intensity tissue also extended to the pelvic sidewall. At surgical pathology, the tumor was determined to be radiation-induced sarcoma of the prostate, and the extraprostatic tissue was postradiation fibrosis.