Effect of quenching temperature and filler rate on the mechanical thermal and physical properties of composites: Polypropylene/calcium carbonate

Polypropylene (PP) is a strong, tough, crystalline thermoplastic material with high performance. Because of its diverse thermo-physical and mechanical properties, it is utilized in a wide variety of disciplines. In this study, the impact of free quenching on the thermo-physical characteristics of PP/calcium carbonate (CaCO3) composites was examined. Three distinct heating procedures were used. First, composites were cooled from their melting phase temperature to ambient temperature. Second, composites were cooled from 130°C to a pre-determined and controlled temperature (T: 0°, 20°, 30°, 40°, 50°, 60°, 70°, 80°C). Third, composites were temperature-tested using annealing. The findings suggest that the elongation-at-break and impact strength may be improved following an initial quenching process from the melting phase to ambient temperature. On the other hand, a second quenching process at 0°C produces superior results, and a correlation between mechanical and thermal characteristics is noted; however, while these qualities are increased, others, such as flexibility, density, Vicat softening temperature (VST), and heat distortion temperature (HDT) are negatively impacted

Epidemiology and management of head injury in paediatric age group in North-Eastern Nigeria

Background: Paediatric head injury (HI) is the single most common cause of death and permanent disability in children world over, and this is increasingly becoming worrisome in our society because of increased risks and proneness to road traffic accidents on our highways and streets. The study set to determine causes and management of HI among children in our society. Patients and Methods: A retrospective review of all children aged 0-15 years with traumatic head injury (THIs) who were managed at the University of Maiduguri Teaching Hospital between July, 2006 and August, 2008. Results: A total of 45 children with THIs presented to the casualty unit of the hospital; 30 (66.7%) were boys and 15 (33.3%) were girls. Three (6.7%) children were less than 1 year of age, 21 (46.7%) were between 1 years and 6 years while 16 (35.6%) and 5 (11.0%) were aged 7-11 years and 12-15 years respectively. Thirty six (80.0%) of the children were pedestrians, 6 (13.4%) fell from a height, while 2 (4.4%) and 1 (2.2% were as a result of home accident and assault, respectively. Twenty one patients (46.7%) had mild HI, while 53.3% had moderate to severe category. Forty one (91.1%) of children were managed as in-patients, mostly (95.1%) by conservative non-operative management, while 4 (8.9%) were treated on the out-patient basis. The mortality rate was 17.8%. Conclusion: H1 among children is of a great concern, because of its incremental magnitude, due to increasing child labour and interstate religious discipleship among children, with attendant high mortality and permanent disabilities. Necessary laws and legislations should be formulated and implemented with organized campaigns and public enlightenment to prevent and mitigate this menace

Synthesis and vasodilator activity of 3,4-dihydropyrimidin-2(1H)-ones bearing urea, thiourea and sulfonylurea moieties

A series of novel 3,4-dihydropyrimidin-2(1H)-ones bearing urea, thiourea and sulfonylurea moieties were synthesized and pharmacologically evaluated as vasodilator agents. The most interesting vasodilators were the thiourea derivatives 6a and 6b, and the urea derivatives 6f-i and 7f-h, although the ureas were relatively more active than thioureas. Twenty fold more active than diazoxide, the urea ÂŹ6k was the most potent vasodilator (EC50 = 0.983 Âą 0.061 ď ­M), and proved to act as a voltage-gated calcium channel blocker. The lack of activity of sulfonylureas, 6k and 7j, could be attributed to their partial ionization at the physiological pH, because of their acidic character. It should be interesting to investigate a larger number of compounds, including N-methylated sulfonylureas, in order to increase the vasodilator activity and to explore other biological models.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Synthesis and vasodilator activity of new 1,4-dihyropyridines bearing sulfonylurea, urea and thiourea moieties

peer reviewedAbstract: Some new 1,4-dihydropyridines bearing sulfonylurea, urea and thiourea moieties were synthesized and pharmacologically evaluated for their vasodilator activity, comparatively to nifedipine and diazoxide. The investigations of the target compounds on rat aorta rings showed that, except the sulfonylureas derivatives, which were inactive (EC50 > 100 μΜ), ureas and thioureas derivatives showed moderate to strong vasodilator activity, with EC50 values varying from 1.2 to 40 μM. 17-fold more active than diazoxide (but less active than nifedipine), the most active compound (1.2 ± 0.2 μM) was found to be a voltage-gated calcium channels blocker, as it is the case for the reference compound, nifedipine. The results also showed that an aliphatic or aromatic R group (the latter bearing electro-donating or electro-withdrawing substituents) gave very active compounds. The inactiveness of sulfonylurea derivatives could be explained by a partial ionization at physiological pH because of their weak acid character. Finally, it would be very suitable to synthesize N-methylated analogs of sulfonylurea derivatives, and more urea and thiourea derivatives bearing aliphatic R groups, and to test them on the same pharmacological model. Therefore, the series of 1,4-dihydropyridines described herein displayed good potential for the development of new vasodilator agents in the search for new therapeutics for the treatment of some cardiovascular diseases. Graphic abstract: [Figure not available: see fulltext.]

Development of Efficient and Recyclable ZnO–CuO/g–C3N4 Nanocomposite for Enhanced Adsorption of Arsenic from Wastewater

Arsenic (III) is a toxic contaminant in water bodies, especially in drinking water reservoirs, and it is a great challenge to remove it from wastewater. For the successful extraction of arsenic (III), a nanocomposite material (ZnO–CuO/g–C3N4) has been synthesized by using the solution method. The large surface area and plenty of hydroxyl groups on the nanocomposite surface offer an ideal platform for the adsorption of arsenic (III) from water. Specifically, the reduction process involves a transformation from arsenic (III) to arsenic (V), which is favorable for the attachment to the –OH group. The modified surface and purity of the nanocomposite were characterized by SEM, EDX, XRD, FT–IR, HRTEM, and BET models. Furthermore, the impact of various aspects (temperatures, pH of the medium, the concentration of adsorbing materials) on adsorption capacity has been studied. The prepared sample displays the maximum adsorption capacity of arsenic (III) to be 98% at pH ~ 3 of the medium. Notably, the adsorption mechanism of arsenic species on the surface of ZnO–CuO/g–C3N4 nanocomposite at different pH values was explained by surface complexation and structural variations. Moreover, the recycling experiment and reusability of the adsorbent indicate that a synthesized nanocomposite has much better adsorption efficiency than other adsorbents. It is concluded that the ZnO–CuO/g–C3N4 nanocomposite can be a potential candidate for the enhanced removal of arsenic from water reservoirs