Free convection heat transfer over a horizontal plate at low prandtl number

Boundary layer equations for free convection heat transfer along a semi-infinite horizontal plate are derived by giving more importance to the energy equation. The equations are obtained for low Prandtl number and two separate polynomials are used to approximate the temperature and velocity profiles in these regions. The rate of heat transfer is compared with the available analytical and numerical results based on conventional boundary layer equations.     

Biobased flexible polyurethane foams manufactured from lactide-based polyester-ether polyols for automotive applications

In this study, biobased polyester-ether polyols derived from meso-lactide and dimer acids were evaluated for flexible polyurethane foams (PUF) applications. Initially, the catalyst concentration was optimized for the biobased PUF containing 30% of biobased polyol (70% petroleum-based polyol). Then, the same formulation was used for biobased PUF synthesis containing 10%–40% of biobased polyols. The performance of biobased PUF was compared with the performance of the control foam made with 100% petroleum-based polyol. The characteristic times (cream, top of the cup, string gel, rise, tack-free) of biobased PUF were determined. The biobased PUF were evaluated for the mechanical (tensile and compressive) and morphological properties. As the wet compression set is important for automotive applications, it was measured for all biobased PUF. The thermal degradation behavior of biobased PUF was also evaluated and compared with the control foam. The effect of different hydroxyl and acid values of polyols on the mechanical properties of biobased PUF is also discussed. The miscibility of all components of PUF formulations is crucial in order to produce a foam with uniform properties. Thus, the miscibility of biobased polyols with commercial petroleum-based polyol was studied.     

Primary focal segmental glomerulosclerosis: clinical course and response to therapy

Primary focal segmental glomerulosclerosis (FSGS) is a lesion associated with a poor prognosis and results in end-stage renal disease after 5 to 10 years. Based on past experience, many nephrologists have considered primary FSGS a lesion that is steroid resistant and therefore are reluctant to offer steroids as treatment. Recent data, however, have demonstrated that patients with primary FSGS have a response to steroid therapy that is considerably better than had been described. Thus, it may be that nephrologists have been more "steroid reluctant" than the lesion is steroid resistant. To better understand this issue we review the clinical course and response to therapy in patients with primary FSGS.     

Disruption of epithelial cell-matrix interactions induces apoptosis

Cell-matrix interactions have major effects upon phenotypic features such as gene regulation, cytoskeletal structure, differentiation, and aspects of cell growth control. Programmed cell death (apoptosis) is crucial for maintaining appropriate cell number and tissue organization. It was therefore of interest to determine whether cell-matrix interactions affect apoptosis. The present report demonstrates that apoptosis was induced by disruption of the interactions between normal epithelial cells and extracellular matrix. We have termed this phenomenon "anoikis." Overexpression of bcl-2 protected cells against anoikis. Cellular sensitivity to anoikis was apparently regulated: (a) anoikis did not occur in normal fibroblasts; (b) it was abrogated in epithelial cells by transformation with v-Ha-ras, v-src, or treatment with phorbol ester; (c) sensitivity to anoikis was conferred upon HT1080 cells or v-Ha-ras-transformed MDCK cells by reverse-transformation with adenovirus E1a; (d) anoikis in MDCK cells was alleviated by the motility factor, scatter factor. The results suggest that the circumvention of anoikis accompanies the acquisition of anchorage independence or cell motility.     

Transfer of loads between lumbar tissues during the flexion-relaxation phenomenon

STUDY DESIGN AND METHODS: This study used an anatomically detailed model of the lumbar tissues, driven from biologic signals of vertebral displacement and myoelectric signals, to estimate individual muscle and passive tissue force-time histories during the performance of the "flexion-relaxation" maneuver. Eight male university students performed three trials each of the "flexion-relaxation" maneuver with six pairs of surface myoelectric electrodes monitoring the right side of the trunk musculature, an electromagnetic device to record lumbar flexion, and videotape to record body segment displacement. OBJECTIVES: To examine the loads on individual tissues during the transfer of moment support responsibility from predominantly active muscle to predominantly passive tissue. SUMMARY OF BACKGROUND DATA: No previous studies, to the authors' knowledge, have examined individual tissue loading during the flexion-relaxation maneuver. RESULTS: Although most subjects were able to "relax" their lumbar extensors in full flexion, activity remained in the thoracic extensors and abdominals. Tissue load predictions suggested that while the lumbar extensor muscles were neurally "relaxed" (i.e., myoelectric silence), substantial elastic forces would assist the passive tissues in extensor moment support. On average, subjects sustained almost 3 kN in compressive load on the lumbar spine and about 755 N of anterior shear during full flexion with only 8 kg held in the hands. CONCLUSIONS: The "relaxation" of lumbar extensor muscles appeared to occur only in an electrical sense because they generated substantial force elastically through stretching. Loading of the interspinous and supraspinous ligaments, in particular, was high relative to their failure tolerance.     

The role of autologous blood transfusion in the the Federal Republic of Germany. Results of a 1993 questionnaire. 1. The reunited Germany

The objective of the study was to evaluate the role of autologous blood transfusion in current clinical practice in the Federal Republic of Germany after reunification. METHODS: Questionnaires were sent to the anaesthesia departments of 684 German hospitals in January 1993. The sample consisted of 400 randomly selected hospitals from the former West Germany ("old federal states") and 284 hospitals from the former German Democratic Republic ("new federal states"). Only hospitals with more than 25 surgical beds were included in the study. The questionnaire contained 36 questions related to (1) general information on the hospital, (2) preoperative autologous blood donation (PABD), (3) preoperative plasmapheresis, (4) isovolaemic haemodilution, (5) perioperative blood salvage, and (6) general management of blood transfusion. RESULTS: A total of 502 completed questionnaires (73%) were returned, 305 from hospitals in the "old federal states" and 197 from hospitals in the former German Democratic Republic. Nine per cent of the responding hospitals were running their own transfusion services, and 56% were located in the vicinity of a regional blood bank. The overall proportion of surgical procedures requiring perioperative blood transfusion ranged from 1% to 90% (median 10%). PABD was performed "not at all" in 18%, "rarely" in 20% "occasionally" in 27%, "frequently" in 17%, and "mostly" in 16% of the responding hospitals. The principal use of PABD was in orthopaedic surgery and cardiac surgery (83% and 70% of the departments in question, respectively). In more than 50% of the hospitals reporting, the PABD service was run by the anaesthesia department. Patients not meeting the established criteria for homologous blood donors were accepted for autologous blood donation "frequently" and "mostly" in 20% and 12% of the hospitals, respectively, but at most "occasionally" in 63% of the hospitals. Preoperative plasmapheresis was performed in 12% of the responding hospitals. Autologous fresh frozen plasma predominantly was used for volume replacement, and for prevention of coagulation disorders when major blood loss was anticipated. Isovolaemic haemodilution was performed "not at all" in 28%, "rarely" in 19%, "occasionally" in 28%, "frequently" in 16%, and "mostly" in 8% of the responding hospitals. The reasons most frequently invoked for not performing haemodilution were "too time consuming" and "too little blood-saving effect". Cell separators for perioperative blood salvage were available in 30% of the responding hospitals. Of the other hospitals not equipped with cell-washing devices, 11% performed perioperative blood salvage of unprocessed blood by means of simple collection devices. Some 80% of those hospitals using intraoperative autotransfusion devices also performed blood salvage postoperatively. The principal use of perioperative blood salvage was in cardiac surgery, orthopaedics, and vascular surgery (90%, 54%, and 54% of departments, respectively). Some 48% of the responding anaesthetists "mostly" considered haemoglobin levels of 8-10 g/dl acceptable in patients without cardiopulmonary disease, but only 18% did so in patients with cardiopulmonary disease. CONCLUSIONS: Although available in the majority of hospitals surveyed, the simple techniques of both PABD and isovolaemic haemodilution are unduly neglected in routine clinical practice. The consistent use of both of these techniques, and the careful weighing up of the indication for every single blood transfusion, would not only effectively reduce homologous blood transfusions, but also enable even small hospitals to run successful autologous transfusion programmes without expensive cell-washing and plasmapheresis devices.     

Strategic questions for consumer-based health communications

Using the consumer-oriented approach of social and commercial marketers, this article presents a process for crafting messages designed to improve people's health behaviors. The process, termed consumer-based health communications (CHC), transforms scientific recommendations into message strategies that are relevant to the consumer. The core of CHC is consumer research conducted to understand the consumer's reality, and thereby allowing six strategic questions to be answered. The immediate result of the CHC process is a strategy statement--a few pages that lay out who the target consumer is, what action should be taken, what to promise and how to make the promise credible, how and when to reach him or her, and what image to convey. The strategy statement then guides the execution of all communication efforts, be they public relations, mass media, direct marketing, media advocacy, or interpersonal influence. It identifies the most important "levers" for contact with the consumer. Everyone from creative specialists through management and program personnel can use the strategy statement as a touchstone to guide and judge the effectiveness of their efforts. The article provides a step by step illustration of the CHC process using the 5 A Day campaign as an example.     

Fuzzy and Deep Belief Network Based Malicious Vehicle Identification and Trust Recommendation Framework in VANETs

Wireless Personal Communications - This work aims to implement a clustering scheme to separate vehicles into a cluster that is based on various parameters, such as the total number of relay nodes,...     

Modulated Triple‐Material Nano‐Heterostructures: Where Gold Influenced the Chemical Activity of Silver in Nanocrystals

For efficient charge separations, multimaterial hetero‐nanostructures are being extensively studied as photocatalysts. While materials with one heterojunction are widely established, the chemistry of formation of multijunction heterostructures is not explored. This needs a more sophisticated approach and modulations. To achieve these, a generic multistep seed mediated growth following controlled ion diffusion and ion exchange is reported which successfully leads to triple‐material hetero‐nanostructures with bimetallic‐binary alloy‐binary/ternary semiconductors arrangements. Ag₂S nanocrystals are used as primary seeds for obtaining AuAg‐AuAgS bimetallic‐binary alloyed metal–semiconductor heterostructures via partial reduction of Ag(I) using Au(III) ions. These are again explored as secondary seeds for obtaining a series of triple‐materials heterostructures, AuAg‐AuAgS‐CdS (or ZnS or AgInS₂), with introduction of different divalent and trivalent ions. Chemistry of each step of the gold ion–induced changes in the rate of diffusion and/or ion exchanges are investigated and the formation mechanism for these nearly monodisperse triple material heterostructures are proposed. Reactions without gold are also performed, and the change in the reaction chemistry and growth mechanism in presence of Au is also discussed.