An investigation of atomic force microscopy,surface topography and adhesion of luting cements to zirconia: effect of silica coating,zirconia primer and laser

This study evaluated the effect various surface conditioning methods on the surface topography and adhesion of luting cements to zirconia. Zirconia blocks (N?=?25) were randomly assigned to five groups according to the surface conditioning methods: (a) No conditioning, control (CON), (b) tribochemical silica coating (TSC), (c) MDP-based zirconia primer (ZRP), (d) coating with nano aluminum nitride (ALN) (e) etching with Er: YAG laser (LAS). The conditioned zirconia blocks were further divided into five subgroups to receive the luting cements: (a) MDP-based resin cement (Panavia F2.0) (PAN), (b) 4-META-based cement (Super Bond) (SUB), (c) UDMA-based (GCem) (GCE), (d) bis-GMA based (Bifix QM) (BIF) and (e) polycarboxylate cement (Poly-F) (POL). Cements were applied in polyethylene moulds (diameter: 3?mm; height: 2?mm). The bonded specimens were first thermocycled for 5500 cycles (5–55?°C) and then adhesive interface was loaded under shear (0.5?mm/min). The data (MPa) were analyzed using 2-way ANOVA, Tukey’s and Bonneferroni tests (alpha?=?0.05). Regardless of the cement type, TSC resulted in significantly higher bond strength (p???0.05) (13.3?±?4.35–25.3?±?6.3) compared to other conditioning methods (2.96?±?1.5–5.4?±?5.47). Regardless of the surface conditioning method, no significant difference was found between MDP, 4-META and UDMA based cements (p?>?0.05) being significantly higher than those of bis-GMA and polycarboxylate cements (p???0.05). Failure types were frequently adhesive in all groups. Tribochemical silica coating provided superior bond results compared to other conditioning methods tested on zirconia especially in conjunction with UDMA- and 4-META-based resin cements.     

Wood-Plastic Composite with Methylmethacrylate in Presence of Novel Additives

Wood–plastic composites (WPC) were prepared with kadom and mango wood of Bangladesh under Co-60 gamma irradiation using methylmethacrylate (MMA) as the bulk monomer mixed with methanol (swelling solvent) at different proportions in presence of a number of additives such as N-vinyl pyrrolidone, tripropylene glycol diacrylate, trimethylol propane triacrylate, copper sulfate, sulfuric acid, and urea. Composites prepared with urea, NVP, and CuSO₄ possess better tensile and protective properties.     

High-quality NiGe/Ge diodes for Schottky barrier MOSFETs

Schottky barrier (SB) Ge channel MOSFETs suffer from high drain-body leakage at the required elevated substrate doping concentrations to suppress source–drain leakage. Here, we show that electrodeposited Ni–Ge and NiGe/Ge Schottky diodes on highly doped Ge show low off current, which might make them suitable for SB-MOSFETs. The Schottky diodes showed rectification of up to five orders in magnitude. At low forward biases, the overlap of the forward current density curves for the as-deposited Ni/n-Ge and NiGe/n-Ge Schottky diodes indicates Fermi-level pinning in the Ge bandgap. The SB height for electrons remains virtually constant at 0.52 eV (indicating a hole barrier height of 0.14 eV) under various annealing temperatures. The series resistance decreases with increasing annealing temperature in agreement with four-point probe measurements indicating the lower specific resistance of NiGe as compared with Ni, which is crucial for high drive current in SB-MOSFETs. We show by numerical simulation that by incorporating such high-quality Schottky diodes in the source/drain of a Ge channel PMOS, highly doped substrate could be used to minimize the subthreshold source to drain leakage current.     

Therapeutic Efficacy of Natural Product ‘C-Phycocyanin’ in Alleviating Streptozotocin-Induced Diabetes via the Inhibition of Glycation Reaction in Rats

Diabetes is a long-term metabolic disorder characterized by persistently elevated blood sugar levels. Chronic hyperglycemia enhances glucose–protein interactions, leading to the formation of advanced glycation end products (AGEs), which form irreversible cross-links with a wide variety of macromolecules, and accumulate rapidly in the body tissues. Thus, the objective of this study was to assess the therapeutic properties of C-phycocyanin (C-PC) obtained from Plectonema species against oxidative stress, glycation, and type 2 diabetes mellitus (T2DM) in a streptozotocin (STZ)-induced diabetic Wistar rat. Forty-five days of C-PC administration decreased levels of triglycerides (TGs), blood glucose, glycosylated hemoglobin, (HbA1c), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), liver and kidney function indices, and raised body weight in diabetic rats. C-PC suppressed biochemical glycation markers, as well as serum carboxymethyllysine (CML) and fluorescent AGEs. Additionally, C-PC maintained the redox state by lowering lipid peroxidation and protein-bound carbonyl content (CC), enhancing the activity of high-density lipoprotein cholesterol (HDL-C) and renal antioxidant enzymes, and preserving retinal and renal histopathological characteristics. Thus, we infer that C-PC possesses antidiabetic and antiglycation effects in diabetic rats. C-PC may also act as an antidiabetic and antiglycation agent in vivo that may reduce the risk of secondary diabetic complications.     

Friction Stir Welding of Stainless Steel to Al Alloy: Effect of Thermal Condition on Weld Nugget Microstructure

Joining of dissimilar materials is always a global challenge. Sometimes it is unavoidable to execute multifarious activities by a single component. In the present investigation, 6061 aluminum alloy and 304 stainless steel were joined by friction stir welding (FSW) at different tool rotational rates. Welded joints were characterized in optical and scanning electron microscopes. Reaction products in the stirring zone (SZ) were confirmed through X-ray diffraction. Joint strength was evaluated by tensile testing. It was found that the increment in average heat input and temperature at the weld nugget (WN) facilitated iron enrichment near the interface. Enhancement in the concentration of iron shifted the nature of intermetallics from the Fe₂Al₅ to Fe-rich end of the Fe-Al binary phase diagram. The peak microhardness and ultimate tensile strength were found to be maxima at the intermediate tool rotational rate, where Fe₃Al and FeAl₂ appeared along with Fe₂Al₅.     

The Kowledge-Based Simulation System

To answer what-if questions, KBS uses artificial intelligence techniques to model complex organizations, recognize cause-and-effect relations, and generates scenarios automatically.     

An audit on hospital management of bronchial asthma

Medical audit is a new concept in developing countries like Pakistan. We carried out this retrospective study on bronchial asthma. The purpose was to see if care given to patient with asthma meets the accepted international standard or not. During this audit several deficiencies were found. Documentation in notes about signs indicating severity of asthma was very poor. Peak flow recording in the notes was also very deficient. There was no documentation in notes whether inhalers technique of the patients has been checked or not. This audit shows that care given to asthma patients is far from satisfactory and we clearly need to improve in order to reach the accepted international standards.     

Schatzki ring in children and young adults: clinical and radiologic findings

BACKGROUND: The Schatzki ring is a well-known clinical and radiologic entity in adults, but is thought to be rare in childhood. Objective. To review the clinical presentations and radiologic findings of children and young adults with Schatzki rings. MATERIALS AND METHODS: A retrospective review of all barium swallow examinations done between 1990 and 1996 revealed 20 patients with Schatzki rings. RESULTS: The most frequent presenting symptoms of these patients were progressive dysphagia with solid food and acute food impaction. Radiographic findings of Schatzki rings were typical in all cases. Twelve patients had endoscopy and all had evidence of esophagitis. CONCLUSION: Schatzki rings are not rare in childhood. The patients are symptomatic, presenting with either progressive dysphagia with solids or acute food impaction. A thorough evaluation of the distal esophagus should be performed in patients with a suggestive clinical history.     

UCN-01 in ovary cancer cells: effective as a single agent and in combination with cis-diamminedichloroplatinum(II)independent of p53 status

Our goal was to determine the cytotoxicity of 7-OH-hydroxystaurosporine (UCN-01) as a single agent and in combination with cis-diamminedichloroplatinum(II) (CDDP) in a panel of ovarian carcinoma cells. We sought to examine the role of p53 gene function and alterations in cell cycle progression or other mechanisms of action of UCN-01 including perturbation of the apoptosis pathway mediated by NF-kappaB and Bcl-2/Bax. Cytotoxicity was determined from dose-response curves established by the Alamar blue vital dye indicator assay. Restoration of wild-type p53 in a p53 null cell line, SKOV 3, was achieved by transfection of a p53 expression vector. Cell cycle distribution was measured by fluorescence-activated cell sorting analysis of ethidium bromide-stained nuclei. Apoptosis was measured by quantitative fluorescence microscopy. NF-kappaB DNA binding activity was measured by electrophoretic mobility shift assay. Bcl-2 and Bax levels were determined by Western immunoblotting. UCN-01 was effective as a cytotoxic agent alone and in combination with CDDP in all cell lines studied, regardless of p53 status. The degree of sensitization to CDDP conferred by UCN-01, however, was found to correlate with p53 gene status. p53 wild-type cells seem to be more sensitive to the cytotoxic effects of the combination of UCN-01 + CDDP than the p53 mutant cells. This was confirmed in cells in which p53 wild-type function was restored by transfection of p53 cDNA, but these cells are also significantly more sensitive to CDDP alone. The effects of UCN-01 on cell cycle progression also appear to be p53 dependent but may not be the primary mechanism of action. The rate of apoptosis is increased 4-fold in UCN-01 + CDDP-treated cells compared to either agent alone. UCN-01 does not effect NF-kappaB DNA binding activity or Bcl-2 and Bax levels. UCN-01 enhances CDDP cytotoxicity and apoptosis in ovary cancer cells. This occurs regardless of p53 status, but wild-type p53 seems to increase the degree of sensitization.