Parameters' Effect on Weld Quality for Dissimilar Spot Welding Between Ferritic Stainless Steel and Low Carbon Steel Sheets

Abstract: This work discusses the effect of main controlling parameters of spot welding process on the quality of dissimilar welded joint between ferritic stainless steel grade 430, FSS with 0.5 mm thickness and low carbon steel, LCS with 0.6 mm thickness sheets. Parameters studied were welding current, welding time and electrode pressure. Metallurgical and mechanical characteristics were determined through microstructure, tensile shear and microhardness examinations. The results of this study showed that the suitable electrode pressure in this dissimilar combination of steels; FSS and LCS; was 0.2MPa (2 bar). It was found also that the welding current is the most influential parameter on weld quality. The best weld strength was obtained at 3.4 KA. Increasing welding current and welding time up to certain level increases the joint strength, after this level the joint strength decreases. Investigations showed also that the dominant structure of the nugget is martensite. The fracture due to tensile shear test was mainly intergranular in ferritic stainless steel side and the fracture mode was button pullout

Mannose-binding lectin deficiency in preterm neonates

Background: Mannose-binding lectin (MBL) is a collagenous protein that plays a role in innate immunity. MBL deficiency is associated with an opsonization defect and has been associated with recurrent infections, especially in immunocompromised individuals. Neonates are considered to be immunocompromised because adaptive immunity has not yet been developed. Objective: This study was done to evaluate the levels of MBL in premature neonates and to determine the relation between MBL deficiency and development of sepsis. Methods: This case- control study was conducted on 64 neonates classified into 2 groups; 39 preterm neonates with gestational age (G.A) <36 weeks and 25 healthy full term neonates. Measurement of mannose-binding lectin (MBL) serum level was done on the first day of life using ELISA technique. Results: Mean MBL plasma level was found to be lower in preterm than full term neonates, yet this difference did not reach statistical significance. There was a negative correlation albeit an insignificant one, between MBL level and GA. The deficient group (those with MBL level ≤0.7μg/ml) had higher incidence of sepsis, albeit an insignificant one, than the non deficient group. A highly significant positive correlation was demonstrated between MBL plasma level in neonatal and umbilical cord blood samples. Conclusion: Premature neonates have low MBL serum levels which could be measured in either their venous or umbilical cord blood efficiently. Further studies are needed to investigate the relationship between MBL deficiency and neonatal sepsis and whether measuring MBL levels might be used to identify which neonates are prone to infections.Keywords: Mannose binding lectin, neonates, preterm, sepsisEgypt J Pediatr Allergy Immunol 2010;8(2):75-8

Spectral-Domain Optical Coherence Tomography of Preclinical Chloroquine Maculopathy in Egyptian Rheumatoid Arthritis Patients

Purpose. To evaluate the role of spectral-domain optical coherence tomography (SD-OCT) in early detection of Chloroquine maculopathy in rheumatoid arthritis (RA) patients. Methods. 40 left eyes of 40 female rheumatoid arthritis patients who received treatment chloroquine for more than one year were recruited in the study. All patients had no symptoms or signs of Chloroquine retinopathy. They were evaluated using SD-OCT, where the Central Foveal Thickness (CFT), parafoveal thickness and perifoveal thickness, average Retinal Nerve Fiber Layer (RNFL) thickness, and Ganglion Cell Complex (GCC) measurements were measured and compared to 40 left eyes of 40 normal females. Results. The mean CFT was found to be thinner in the Chloroquine group (238.15 µm ± 22.49) than the normal controls (248.2 µm ± 19.04), which was statistically significant (p value = 0.034). The mean parafoveal thickness was lesser in the Chloroquine group than the control group in all quadrants (p value 0.05) in all quadrants. No significant difference was detected between the two groups regarding RNFL, GCC, or IS/OS junction. Conclusions. Preclinical Chloroquine toxicity can lead to early thinning in the central fovea as well as the parafoveal regions that is detected by SD-OCT

Design, synthesis and cytotoxic evaluation of 2-amino-4- aryl-6-substituted pyridine-3,5-dicarbonitrile derivatives

Purpose: To synthesize novel pyridine derivatives and evaluate their efficiency as potent inhibitors of cyclin dependent kinase 2 (CDK2) enzyme for cancer therapy.Methods: Pyridine scaffold were synthesized using one-pot multicomponent condensation reaction of arylidine with different primary amines. The cytotoxic potential of the new compounds was assessed using various cell lines. Furthermore, molecular docking studies based on the crystal structure of CDK2 was carried out to determine the possible binding modes that influence the anticancer activities.Results: The results indicate that one-pot multicomponent reaction generated a series of functionalized pyridines with good yield. In vitro cytotoxicity study revealed superior cytotoxicity of the designed compounds against prostate and cervical cancer cell lines compared to 5-fluorouracil (standard anticancer compound) with half-maximal inhibitory concentration (IC50) values of 0.1 – 0.85 and 1.2 –74.1 μM, respectively. Finally, molecular modeling simulation of the newly synthesized compounds showed that they fit well and are stabilized into CDK2 active site via hydrogen bonding and hydrophobic interactions.Conclusion: The results indicate that the newly synthesized pyridine can exert potent anticancer activity presumably via inhibition of CDK2. However, this will need to be confirmed in in vivo studies

Pre-formulation and systematic evaluation of amino acid assisted permeability of insulin across in vitro buccal cell layers

The aim of this work was to investigate alternative safe and effective permeation enhancers for buccal peptide delivery. Basic amino acids improved insulin solubility in water while 200 and 400 µg/mL lysine significantly increased insulin solubility in HBSS. Permeability data showed a significant improvement in insulin permeation especially for 10 µg/mL of lysine (p < 0.05) and 10 µg/mL histidine (p < 0.001), 100 µg/mL of glutamic acid (p < 0.05) and 200 µg/mL of glutamic acid and aspartic acid (p < 0.001) without affecting cell integrity; in contrast to sodium deoxycholate which enhanced insulin permeability but was toxic to the cells. It was hypothesized that both amino acids and insulin were ionised at buccal cavity pH and able to form stable ion pairs which penetrated the cells as one entity; while possibly triggering amino acid nutrient transporters on cell surfaces. Evidence of these transport mechanisms was seen with reduction of insulin transport at suboptimal temperatures as well as with basal-to-apical vectoral transport, and confocal imaging of transcellular insulin transport. These results obtained for insulin is the first indication of a possible amino acid mediated transport of insulin via formation of insulin-amino acid neutral complexes by the ion pairing mechanism