Pulsed electrodeposition of (Bi1-xSbx)2Te3 thermoelectric thin films

(Bi_1-xSb_x)₂Te₃ thermoelectric thin films were deposited on stainless steel discs in 1 M perchloric acid and 0.1 M tartaric acid by pulse electrodeposition in order to optimize the grain growth. The influence of the electrolyte composition, the cathodic current density and the cathodic pulse time on film stoichiometry were studied. The results show that it is necessary to increase the Sb content in the electrolyte to obtain the (Bi_0.25Sb_0.75)₂Te₃ film stoichiometry. Pulse plating reduced the grain size and the roughness, compared with continuous plating. Thermoelectric and electrical properties were also studied and it was found that the Seebeck coefficient and electrical resistivity were related to two parameters: the cathodic pulse current density and the films thickness.     

Control of heat transfer and growth uniformity of solidifying copper shells through substrate temperature

To determine the optimal roll temperature in a twin-roll copper-strip caster, copper blocks preheated between 25 °C and 350 °C were immersed in a bath of molten copper for 0.5 seconds. A significant increase in the contact heat-transfer coefficient at the substrate-shell interface was obtained when the substrates were heated above 200 °C and the gain in the solidified shell thickness was 20 pct. The shell growth was also approximately 35 pct more uniform at a high substrate temperature, and micrographic examination showed the dendritic structure to be finer. The contact heat-transfer coefficient was decomposed into two constituents, one for the substrate and the other for the shell. The former was found to be the limiting factor in heat transfer.     

A new way of access into the internal jugular vein

This paper describes a new technique for the canulation of the internal jugular vein. A transsection of the neck at the level of C4 (upper border of the thyroid cartilage) (Figure 1) shows the relative position of the internal jugular vein, the carotid artery and the sternocleidomastoid muscle. The internal jugular vein at this level is more superficial than is usually imagined. A cutaneous point of entry placed at the level of the thyroid cartilage on the medial border of the sternocleidomastoid muscle would be directly above, at the zenith of the carotid artery. From that point, moving a needle externally hugging the posterior aspect of the muscle will make it possible to reach the vein while actually moving away from the carotid artery.     

Structural Changes in Tribo-Stressed Zinc Polyphosphates

The influences of pressure, shear stress and temperature on the structure of zinc orthophosphate and zinc metaphosphate was investigated. Tribological tests were performed to study the combined effect of pressure and shear stress at two temperatures. Friction tests were carried out in the boundary lubrication regime from dispersions of zinc polyphosphates in base oil. The effects of pressure alone were investigated using a diamond anvil cell in order to separate it from those of shearing. Raman spectroscopy was used to follow in situ or ex situ the structural changes of the zinc polyphosphate powders and the tribo-stressed areas. Tribofilms obtained with both polyphosphates display a partial and full depolymerization of the zinc metaphosphate at ambient and high (120 °C) temperature, respectively. The large stress and strain conditions of the tribological tests are necessary to induce a tribochemical reaction between zinc metaphosphate and iron oxide leading to a depolymerization of the phosphate in the tribofilm. The tribochemical reaction and antiwear tribofilm formation are significantly enhanced by the modest temperature increase from ambient to 120 °C. Pressure alone induces only disordering in the structure of zinc polyphosphates, with only minor changes of the chain length in phosphates and does not contribute significantly to the observed structural changes in tribofilms.     

Graded Casting of Materials with Continuous Gradients

A process is introduced for producing continuously graded materials by slip casting with a continuous flow of slip of changing composition. The approach has been tested using alumina and zirconia slips to produce alumina/zirconia composites with a graded composition. Observation of the microstructure has shown that the phases are relatively well dispersed. Compositional analysis revealed a relatively smooth transition in composition through the thickness of sintered bodies. Results have also indicated that for flow rates up to ∼ 60 cm/min, the highest linear flow rate tested, the casting rate of alumina slips containing 38.6 vol% solids was not affected.     

Liquefaction Susceptibility Criteria for Silts and Clays

New liquefaction susceptibility criteria for saturated silts and clays are presented that are based on the mechanics of their stress-strain behavior and which provide improved guidance for selecting engineering procedures for estimating potential strains and strength loss during seismic loading. Monotonic and cyclic undrained loading test data for silts and clays show that they transition, over a fairly narrow range of plasticity indices (PI), from soils that behave more fundamentally like sands (sand-like behavior) to soils that behave more fundamentally like clays (clay-like behavior), with the distinction having a direct correspondence to the type of engineering procedures that are best suited to evaluating their seismic behavior. It is recommended that the term liquefaction be reserved for describing the development of significant strains or strength loss in fine-grained soils exhibiting sand-like behavior, whereas the term cyclic softening failure be used to describe similar phenomena in fine-grained soils exhibiting clay-like behavior. For practical purposes, clay-like behavior can be expected for fine-grained soils that have PI ≥ 7, although a slightly lower transition point for soils with a CL-ML classification (perhaps PI ≥ 5 or 6) would be equally consistent with the available data. Issues related to the practical application of these criteria are discussed.     

Acute and long-term outcomes of extremely injured blunt trauma victims

Long-term outcomes after blunt trauma remain poorly defined. The purpose of this study was to document such outcomes in extremely injured adults (Injury Severity Score > or = 50). From April 1990 to June 1993, 76 patients (5% of all trauma victims) had an ISS > or = 50 at a single trauma center. Thirty-five (46%) survived to hospital discharge. The mean duration of hospital stay was longer for survivors than for nonsurvivors (92 days versus 16 days, p < 0.001). Of the 35 survivors, 26% were discharged directly home, 60% to a rehabilitation hospital, 8% to a chronic care facility, and 6% to an acute care hospital. After a mean follow-up of 27 months, 6% had died, 9% refused participation, and the remaining 30 patients (91% of long-term survivors) demonstrated significant residual disabilities in physical, emotional, and mental health status. We suggest that extremely injured patients comprise a small proportion of blunt trauma victims, consume substantial acute care hospital resources, often survive, and yet frequently have residual disability. A reduction in this long-term disability may represent the greatest challenge in modern trauma care.     

Vaccination of patas monkeys experimentally infected with Schistosoma haematobium using a recombinant glutathione S-transferase cloned from S. mansoni

The capacity of a recombinant glutathione S-transferase from Schistosoma mansoni (rSm28GST) to vaccinate primates (Erythrocebus patas) against a heterologous infection with Schistosoma haematobium has been tested. Two injections of the purified molecule with Muramyl-Di-Peptide (MDP) as adjuvant resulted in a high level antibody response in the five immunized animals and in a significant reduction in worm fecundity compared to the controls which received adjuvant alone. Mean levels of daily egg excretion in urine an faeces were reduced by respectively 55% and 74% although perfusion revealed that worm burdens were similar in both groups. The protective effect was long lasting since it was maintained up to the end of the experiment, 42 weeks after infection. Hatching rates and the numbers of intra-uterine eggs were also significantly affected by the vaccination. Tissue eggs were also drastically diminished in the urogenital system (-80%) but the reduction was not statistically significant. One animal was not protected by the immunization. There was a good correlation between parasitological data and the intensity of bladder lesions assessed by microscopic examination. Polypoid formations together with an intense exudation of the lamina propria were frequently seen in the controls but rarely in the vaccinated group where formation of scar tissue was predominant. These results underline the vaccine potential of the recombinant Sm28GST as a possible valuable prophylactic tool for the control of egg-induced pathology and transmission of African schistosomes.     

Postshaking Shear Strain Localization in a Centrifuge Model of a Saturated Sand Slope

This paper presents analyses of a test conducted on a 9-m-radius centrifuge to study the redistribution of pore water during diffusion of earthquake-induced excess pore pressures in a sand slope with embedded silt layers. The centrifuge model developed large postshaking deformations associated with shear strain localization at the interface between the sand and silt layers. Dense arrays of pore pressure transducers provided detailed measurements of pore pressure variations in time and space within the slope. A new data analysis approach is presented in which measured pore-pressures are used to compute flow rates and volumetric strains as a function of time and position throughout the slope. Hydraulic gradients were calculated by numerical differentiation of measured pore-pressure distributions with respect to position. Flow rates that were based on Darcy’s law were then integrated with respect to time to obtain flow quantities, from which volumetric strains were computed. A second data analysis approach that computes volumetric strains on the basis of soil compressibility and changes in pore pressure provided an independent computation of strains in consolidating zones. Results using these data analysis procedures confirm that a dilating (loosening) zone of significant thickness developed in the sand immediately beneath an embedded silt layer that had impeded the drainage of high pore pressures. These results support the hypothesis that the dilating zone corresponds to regions where the mobilized friction angle exceeds the critical state friction angle and that the dilating zone can be initially relatively thick before its size diminishes to the thickness of a thin shear band after the peak friction angle is mobilized. Quantification of the evolution of the size of the dilating zone is a key to understanding the magnitude of deformations associated with void redistribution.