Structural Texture Induced in SnSe Thermoelectric Compound via Open Die Pressing.

Outstanding ZT values registered on single crystals recently renewed the interest of thermoelectric community for SeSn compound. Owing to the strong anisotropy of the phenomenon, so far only single crystals proved to be the suitable for its application. Here we present the production and the characterization of bulk polycrystalline materials processed by open die pressing, aimed at reducing the gap with single crystal materials by taking advantage from the highly texture degree derived by the processing and by the improved phonon scattering promoted by grain boundaries. The resulting bulks display good compaction, improved mechanical properties and strong texture of the phase. Structural and morphological analyses confirmed the successful orientation according to the (400) cleavage plane. The structural transition responsible for the ultra-low thermal conductivity has been investigated and possible irreversible effects on the starting phase due to thermal cycling have been evaluated. Preliminary measurements of thermal conductivity are reported.

Flow softening and recrystallization accompanied flow in AZ61 magnesium alloy during thermomechanical processing.

The present work deals with characterizing the recrystallization accompanied flow and high temperature softening behavior of an extruded AZ61 magnesium alloy. This was supported by conducting a set of hot compression tests at temperatures in the range of 250-450 °C under the strain rate ranging from 0.001 to 0.1s-1. The flow curves at all thermomechanical conditions indicated high fractional softening representing the domination of dynamic recrystallization mechanism. Through a new quantitative approach, "Arrhenius type model", "modified Avrami equations" and Poliak and Jonas method were simultaneously employed to investigate the kinetic of dynamic recrystallization. It was revealed that the strain required for the same amount of recrystallization fraction increased with decreasing deformation temperature, and at a specified temperature, the required strain increases with increasing strain rate. Interestingly, an anomaly was found at 400 °C under the strain rate of 0.001s-1, where the recrystallization kinetic was faster than that of what was recorded at 450 °C. This anomaly was discussed relying on the nanoprecipitation of γ-phase at the prior boundaries and sub-boundaries which prohibited the grain boundary migration and also the rotation and coalescence of adjacent sub-grains.

Bilateral tubal ligation in a rural hospital in the Niger Delta, Nigeria.

BACKGROUND AND OBJECTIVE: To document bilateral tubal ligation (BTL) rates and highlight the need to improve on the rates. MATERIALS AND METHODS: A retrospective review of BTLs done in a five-year period from January 2000 to December 2004 constituted the study group. RESULTS: There were a total of 103 BTLs, 58 were Caesarean BTLs, six were cases of BTL with repair of uterine rupture and 39 had BTL from mini-laparotomy. There were 937 Caesarean sections and 2,356 deliveries during the study period. BTL therefore constituted 0.044% of the total deliveries. The majority (51.7%) were above 35 years of age and grandmultiparity constituted 60.4% of BTL cases. The majority was in the low social Class 4 and 5 (41.3%). Grandmultiparity was the most common indication (60.4%). Previous Caesarean sections were more in the highest social class with a mean of 2.9 ± 1.21 while ruptured uterus had the lowest. Unbooked cases of BTL constituted 62.1% of BTL. CONCLUSIONS: Bilateral tubal ligation rate was low in this study with grandmultiparity being the commonest indication, the majority of patients were elderly parturient and largely unbooked. Social class was highest among those with previous Caesarean section.

Comparing the mechanical properties, microstructure, texture and in-vitro degradation behavior of TNTZ/nano-fluorapatite composite and TNTZ bioalloy.

The present study deals with (i) the fabrication of the composite surface layer of Ti-29Nb-13Ta-4.6Zr/nano-fluorapatite through friction stir processing, (ii) clarifying the correlation of microstructure and texture with in-vitro degradation behavior and bioactivity of fabricated nano-biocomposite, and (iii) comparing the mechanical and functional properties of nano composite whit those obtained for TNTZ bio-alloy. The results indicated that increasing the number of deformation passes effectively refines the microstructure, leading to the average grain sizes of less than 5 µm. The texture of the material was also evolved in the presence of the nano particles where the grains reorient along <111> direction in contrast to the <101>-oriented grains in the starting microstructure. In-vitro bioactivity of the processed samples was measured after being immersed in simulated body fluid solution for various duration up to 30 days. Enhanced corrosion resistance and bio-mineralization of nanocomposite surface layer was discussed relying on the occurrence of grain refinement, substructure development and evolution of texture components along <101> direction. Assessment of the mechanical properties of the fabricated composites and as-received material also indicated the positive effect of the applied processing route and the presence of nano particles.

Designing and Developing Automatic Trolley for Washing and Dressing the Wounds.

INTRODUCTION: Many items are needed for dressing including sterile dressing set, antiseptic and washing solutions, leucoplast tape, waste bin for infectious garbage, waste bin for noninfectious garbage, safe disposal trash for sharp cutting instruments, bedpan and sometimes drugs. All the items are laid out on a simple wheeled trolley. The multiplicity of items together with problems in placing tools on trolley, forgetting some items, disturbing sterile condition, falling and damaging equipment and the need for at least two people for each procedure, all are the reasons to design and develop Automatic Trolley for Washing and Dressing the Wounds. MATERIAL AND METHOD: To develop a mobile unit which meets our needs for dressing, the trolley patents registered in America and different companies were evaluated as well as the materials and methods used while dressing were considered. RESULTS: Automatic Trolley for Washing and Dressing the Wounds was designed and developed. It comprises the followings: drawer, waste bin for infectious garbage, waste bin for noninfectious garbage, shelves for serum and betadine solution, serum stand, peristaltic pump, flexible tube for connecting serum, a place for bedpan, foot pedal for serum flow, two eye-sensor chambers for solution betadine and scrub, an auxiliary work surface. CONCLUSION: Due to the usual requirements for dressing, we have designed an equipped mobile unit which covers all the objectives of dressing and increases the speed of procedure. Moreover, due to the contrived equipment on the trolley, procedures are done quickly and second person is not required to assist. Automatic Trolley for Washing and Dressing the Wounds is made up of stainless steel which could be mass housing and commercializing which would play a deserving role in improving the fundamentals of health care and wound treatment.

Signalling mechanisms in the regulation of vascular cell migration.

The migration of arterial vascular smooth muscle cells (VSMC) is thought to play a central role in atherogenesis and restenosis. The migration of several other cell types, including monocytes, T-lymphocytes and endothelial cells is also involved in the development of the mature atherosclerotic lesion. Several defined growth factors, cytokines and extracellular matrix components which are released at the sites of lesions have been implicated in the regulation of migration of VSMC and other lesion-associated cells. Platelet-derived growth factor BB-homodimer of PDGF (PDGF-BB) is strongly implicated in neo-intima formation in vivo and is the most potent known chemoattractant for VSMC in vitro. Dynamic interactions between cell surface adhesive receptors (integrins) for ECM components, organisation of the actin cytoskeleton and the turnover of focal adhesions are all key processes in cell locomotion and migration. The signal transduction pathways which mediate the chemotactic effects of PDGF-BB and other migration factors on VSMC are unknown, but several classes of cellular components are implicated including components associated with focal adhesions, small GTP-binding proteins of the rho family, and certain substrates of the PDGF beta-receptor. Tyrosine phosphorylation of the novel focal adhesion-associated protein tyrosine kinase, p125 focal adhesion kinase (p125FAK), is regulated by integrins and by several factors which alter actin cytoskeletal organisation. Recent findings suggest that tyrosine phosphorylation of p125FAK and other focal adhesion-associated proteins may be implicated in the chemotactic response of VSMC to PDGF-BB. The migratory response to PDGF-BB may be dependent on both ligand isoform bio-availability and on receptor-isotype expression as well as on down-stream signalling events. Ultimately, cell migration in vivo will be determined by a complex array of diverse extracellular molecules organised in intercellular paracrine/autocrine networks as well as multiple interacting intracellular signal transduction pathways.

Platelet-derived growth factor-BB (PDGF-BB) regulation of migration and focal adhesion kinase phosphorylation in rabbit aortic vascular smooth muscle cells: roles of phosphatidylinositol 3-kinase and mitogen-activated protein kinases.

OBJECTIVE: Phosphatidylinositol 3'-kinase (PI3-kinase) is implicated in cell migration and focal adhesion kinase (FAK) phosphorylation. In contrast, it has been proposed that mitogen-activated protein (MAP) kinases are essential for proliferation but may be dissociated from chemotactic signalling. We investigated the roles of PI3-kinase and p42/p44 MAP kinases in cell migration and FAK tyrosine phosphorylation induced by platelet-derived growth factor-BB (PDGF-BB) in rabbit aortic vascular smooth muscle cells (VSMCs). The roles of PI3-kinase and MAP kinase pathways in the chemotactic response to insulin-like growth factor-I (IGF-I) were also examined. METHODS: The roles of PI3-kinase and p42/p44 MAP kinases were assessed using the PI3-kinase inhibitors, wortmannin and LY294002, and an inhibitor of MAP kinase kinase, PD98059. PI3-kinase activity was measured by phosphatidylinositol phosphorylation in anti-phosphotyrosine immunoprecipitates and by thin layer chromatography of phosphorylated products. Phosphorylation was assessed by immunoprecipitation with anti-phosphotyrosine antibodies and Western blotting with FAK-specific antibody. Migration was evaluated in a chemotaxis chamber using polycarbonate filters with an 8-mm pore size. RESULTS: Neither wortmannin nor LY294002 significantly reduced PDGF-BB stimulation of FAK tyrosine phosphorylation, chemotaxis or immunofluorescent staining of focal adhesions in VSMCs. PD98059, a specific inhibitor of MAP kinase activation, did not inhibit FAK tyrosine phosphorylation but markedly inhibited the migratory response of VSMCs to PDGF-BB. IGF-I also stimulated migration of VSMCs, and, relative to the effect of PDGF-BB, induced smaller increases in PI3-kinase and MAP kinase activities. Both wortmannin and PD98059 partially inhibited the migratory response to IGF-I. CONCLUSIONS: PDGF-BB stimulation of both FAK tyrosine phosphorylation and migration in VSMCs are not dependent on activation of PI3-kinase. While PDGF-BB stimulation of FAK tyrosine phosphorylation is not dependent on p42/p44 MAP kinase activation, PDGF-BB and IGF-I both stimulate p42/p44 MAP kinase activity and the chemotactic response to these factors is partially dependent on MAP kinase activation.

VEGF gene transfer reduces intimal thickening via increased production of nitric oxide in carotid arteries.

Thickening of the arterial intima and smooth muscle cell (SMC) proliferation remain major problems after vascular surgery and other types of vascular manipulations. We studied the effect of endothelial cell (EC)-specific vascular endothelial growth factor (VEGF) gene transfer on the thickening of the intima using a silicone collar inserted around carotid arteries that acted both as the agent that caused intimal SMC growth and as a reservoir for the transfected gene. The model preserved EC integrity and permitted direct extravascular gene transfer without any intravascular manipulation. Compared to beta-galactosidase (lacZ)-transfected control arteries, plasmid/liposome-mediated VEGF gene transfer significantly reduced intimal thickening 1 week after the gene transfer. Administration to the experimental animals of the nitric oxide (NO) synthase inhibitor L-NAME abolished the difference in intimal thickening between VEGF and lacZ-transfected arteries. Furthermore, VEGF caused NO release from cultured human umbilical vein EC. It is concluded that extravascular VEGF gene transfer attenuates intimal growth and could be useful for the prevention of intimal thickening during vascular surgery. Our results further suggest that VEGF may reduce SMC proliferation via a mechanism that involves VEGF-induced NO production from the endothelium.

Rapid activation of the novel serine/threonine protein kinase, protein kinase D by phorbol esters, angiotensin II and PDGF-BB in vascular smooth muscle cells.

Protein kinase D (PKD) is a novel serine/threonine kinase structurally distinct from all protein kinase C (PKC) isoforms but which like classic and novel PKCs is activated by phorbol esters and diacylglycerol. This study investigated the regulation of PKD in vascular smooth muscle cells (VSMC) by physiological regulators of VSMC function and growth factors. Treatment of rabbit aortic VSMC with phorbol ester, angiotensin II and PDGF-BB all stimulated PKD activity in a time- and concentration-dependent manner in VSMC. The effect of angiotensin II was particularly rapid and potent (maximum stimulation within 1 min and at 0.5 nM). In contrast, the maximum effect of PDGF-BB was obtained after 5 min. Other factors, including basic FGF, IGF-I, IGF-II, endothelin-1 and endothelin-2, had no effect on PKD activity in VSMC. These results show for the first time that PKD activity is regulated in VSMC, and is activated by the vasoconstrictor angiotensin II. PKD may be an important mediator for the biological function(s) of one or more PKC isoforms in VSMC and/or may represent a component of a novel PKC-independent signalling pathway in VSMC.

A comparative study of root-end induction using osteogenic protein-1, calcium hydroxide, and mineral trioxide aggregate in dogs.

Calcium hydroxide has been the material of choice for apexification. The purpose of this study was to compare the efficacy of osteogenic protein-1 and mineral trioxide aggregate with that of calcium hydroxide in the formation of hard tissue in immature roots of dogs. Sixty-four roots of premolars were used. After induction of periradicular lesions, the canals were debrided and filled with calcium hydroxide for 1 wk. After the removal of calcium hydroxide, the root canals received one of the treatment materials in a balanced design. The animals were euthanized 12 wk later. The degree of hard tissue formation and amount of inflammation were evaluated histomorphically. Data were statistically evaluated using ANOVA, chi 2, and Kruskal-Wallis. Mineral trioxide aggregate produced apical hard tissue formation with significantly greater consistency. The difference in the amount of hard tissue produced among the three test materials was not statistically significant. Furthermore, the degree of inflammation was not significantly different between the various test groups.

Tissue reaction to implanted root-end filling materials in the tibia and mandible of guinea pigs.

The purpose of this study was to examine the tissue reaction to implanted mineral trioxide aggregate (MTA), amalgam, Intermediate Restorative Material, and Super-EBA in the tibias and mandibles of guinea pigs. After anesthetizing 20 guinea pigs, raising tissue flaps, and preparing bony cavities, the test materials were placed in Teflon cups and implanted in the tibias and 10 days later in the mandibles. The animals were euthanized 80 days later and the tissues prepared for histological examination. The presence of inflammation, predominant cell type, and thickness of fibrous connective tissue adjacent to each implant were recorded. The tissue reaction to MTA implantation was the most favorable observed at both sites; as in every specimen, it was free of inflammation (p < 0.01). In the tibia, MTA was the material most often observed with direct bone apposition. Based on these results, MTA seems to be a biocompatible material.

Histologic assessment of mineral trioxide aggregate as a root-end filling in monkeys.

Mineral Trioxide Aggregate (MTA) has been shown in a number of experiments to be a potential root-end filling material. The purpose of this study was to examine the periradicular tissue response of monkeys to MTA and amalgam as root-end fillings. The pulps were removed from all the maxillary incisors of three monkeys. The root canals were prepared and filled with laterally condensed guttapercha and sealer, and the access cavities were restored with amalgam. Buccal mucoperiosteal flaps were raised, and root-end resections were performed before root-end cavity preparation with burs. The root-end cavities in half of the teeth were filled with MTA, while amalgam was placed in the other cavities. After 5 months the periradicular tissue response was evaluated histologically. The results showed no periradicular inflammation adjacent to five of six root ends filled with MTA; also five of six root ends filled with MTA had a complete layer of cementum over the filling. In contrast, all root ends filled with amalgam showed periradicular inflammation, and cementum had not formed over the root-end filling material, although it was present over the cut root end. Based on these results and previous investigations, MTA is recommended as a root-end filling material in man.

Is routine antenatal screening for syphilis useful?

The incidence of positive antenatal syphilis serology is low in Benin City. Routine serological screening should continue with the inclusion of confirmatory treponemal antigen tests.

Carcinoma of the cervix: aspects of clinical presentation and management in Benin City.

Carcinoma of the cervix is the most common gynecological cancer in Benin City. Late presentation, poverty and grand multiparity featured prominently. Multiplicity of sexual partners was rather uncommon.

Effects of ultrasonic root-end cavity preparation on the root apex.

This study determined the effect of bur and ultrasonic preparation on the root apex. After cleaning, shaping, and obturation of root canals of 47 single-rooted teeth and resection of their apexes were done, 24 root-end cavities were prepared with a bur, and the rest were prepared with ultrasonic tips attached to two different ultrasonic units. After photographs of the prepared root ends were taken, their resin replicas were prepared and examined with a scanning electron microscope. Photographs and scanning electron microscope photomicrographs were examined for the presence or absence of cracks. The results showed a significantly higher incidence of crack formation in the walls of root-end cavities prepared by ultrasonic tips compared with those made by the bur.

Using mineral trioxide aggregate as a pulp-capping material.

This study examined the dental pulp responses in monkeys to mineral trioxide aggregate, or MTA, and a calcium hydroxide preparation when used as pulp-capping materials. After the pulps of 12 mandibular incisors were exposed with a No. 1 round bur, they were capped with either MTA or the calcium hydroxide preparation. After five months, the authors noted no pulpal inflammation in five of six samples capped with MTA, and all six pulps in this group had a complete dentin bridge. In contrast, all of the pulps capped with the calcium hydroxide preparation showed pulpal inflammation, and bridge formation occurred in only two samples. Based on these results, it appears that MTA has the potential to be used as a pulp-capping material during vital pulp therapy.

Mineral trioxide aggregate: a review of a new cement.

The most common materials in endodontics are gutta-percha and sealer. For certain tasks, however, such as repairing perforations or filling apical preparations, a special-purpose material is needed. The "ideal" special-purpose material in endodontics is still elusive. Most of the materials available today have found their way into endodontics from the restorative field without much consideration of the special conditions and requirements of the periradicular tissues. To address some of the these shortcomings, a material called Mineral Trioxide Aggregate cement (MTA) has been developed at Loma Linda University to seal off the pathways of communication between the root canal system and the external surface of the tooth. At LLU, a series of experiments have been conducted to assess the suitability of this new cement. The experiments began with physical properties of the material and biocompatability studies, followed by clinical studies. The results have been promising, offering for the first time the possibility of regeneration rather than just repair.

Incidence of birth asphyxia as seen in central hospital and GN children's clinic both in Warri Niger Delta of Nigeria: an eight year retrospective review.

BACKGROUND: Birth asphyxia is one of the commonest causes of neonatal morbidity and mortality in developing countries. Together with prematurity and neonatal sepsis, they account for over 80% of neonatal deaths. AIM: To determine the incidence and mortality rate of birth asphyxia in Warri Niger Delta of Nigeria. MATERIALS AND METHOD: Recovery of case notes of all the newborn babies seen from January 2000 to December 2007 at Central Hospital Warri and GN children's Clinic, Warri, was undertaken. They were analyzed and those with birth asphyxia were further analyzed, noting the causes, severity of asphyxia, sex of the babies, management given. RESULTS: A total of 864 out of 26,000 neonates seen within this period had birth asphyxia. 525 (28/1000 live births) had mild asphyxia while 32% were severely asphyxiated. 61.5% of the asphyxiated were born at maternities, churches or delivered by traditional birth attendants or at home. Prolonged labour was the commonest cause of asphyxia and asphyxia was more in neonates from unbooked patients. CONCLUSION: The incidence of bith asphyxia in Warri is 28/1000. Majority of patients are from prolonged labour and delivery at unrecognized centres. Health education will dratically reduce the burden of asphyxia neanatorum as unsubtanciated religous beliefs have done a great havoc.

Determination of very low levels of gold and palladium in wastewater and soil samples by atomic absorption after preconcentration on modified MCM-48 and MCM-41 silica.

A simple and rapid method was applied for extraction, preconcentration and determination of trace amounts of gold and palladium in wastewater by using functionalized mesoporous silica. Extraction was investigated on adsorbents prepared by grafting aminopropyl on the surface of MCM-41 and MCM-48 mesoporous silica. The optimum experimental conditions such as pH, flow rates, type and the smallest amount of eluent for elution of Au and Pd, break through volume and the influence of various cationic interferences on the sorption of gold(III) and palladium(II) were evaluated. The extraction efficiency for gold and palladium were greater than 98% and limit of detection (LOD) was lower than 0.06ng mL(-1) for gold and 0.1ng mL(-1) for palladium on both functionalized MCM-41 and MCM-48 silica. The preconcentration factor was greater than 800 for gold and 400 for palladium and the relative standard deviation (RSD) of the method was <1%. The adsorption capacity of the mesoporous silica was greater than 285mg g(-1) for Au and 145mg g(-1) for Pd on both functionalized MCM-41 and MCM-48 silica. The results of MCM-41 were compared with those of MCM-48 under similar experimental conditions, the results show that flow rate was the single point of difference among the procedures. MCM-48 has similar recovery to MCM-41 at higher flow rates only under identical conditions. The proposed method was applied for the determination of gold(III) and palladium(II) in some real samples, including wastewater and soil samples.