Effect of Cd2+ on the Growth and Thermal Properties of K2SO4 crystal

Single crystals of pure and Cd2+ doped potassium sulfate were grown from aqueous solutions by the slow evaporation technique. From nutrient solutions with a CdSO4 concentration of 4wt.% crystals containing 0.014wt.% dopant concentration could be obtained. The X-ray diffraction patterns of powdered crystals confirmed their crystal structures for both cases. Thermal analysis of pure crystals shows that the alpha-beta phase transformation peak around 580 deg C is superimposed with spurious effects, while for Cd2+ doped crystals this is not the case. The thermal hysteresis of the phase transition is 8 K for undoped K2SO4 and is reduced to 3.5 K for K2SO4:Cd2+. Compared to undoped crystals, the optical transmittance of Cd2+ doped crystals is higher.Comment: 5 pages, 6 figure

Is there a common water-activity limit for the three domains of life?

Archaea and Bacteria constitute a majority of life systems on Earth but have long been considered inferior to Eukarya in terms of solute tolerance. Whereas the most halophilic prokaryotes are known for an ability to multiply at saturated NaCl (water activity (a w) 0.755) some xerophilic fungi can germinate, usually at high-sugar concentrations, at values as low as 0.650-0.605 a w. Here, we present evidence that halophilic prokayotes can grow down to water activities of <0.755 for Halanaerobium lacusrosei (0.748), Halobacterium strain 004.1 (0.728), Halobacterium sp. NRC-1 and Halococcus morrhuae (0.717), Haloquadratum walsbyi (0.709), Halococcus salifodinae (0.693), Halobacterium noricense (0.687), Natrinema pallidum (0.681) and haloarchaeal strains GN-2 and GN-5 (0.635 a w). Furthermore, extrapolation of growth curves (prone to giving conservative estimates) indicated theoretical minima down to 0.611 a w for extreme, obligately halophilic Archaea and Bacteria. These were compared with minima for the most solute-tolerant Bacteria in high-sugar (or other non-saline) media (Mycobacterium spp., Tetragenococcus halophilus, Saccharibacter floricola, Staphylococcus aureus and so on) and eukaryotic microbes in saline (Wallemia spp., Basipetospora halophila, Dunaliella spp. and so on) and high-sugar substrates (for example, Xeromyces bisporus, Zygosaccharomyces rouxii, Aspergillus and Eurotium spp.). We also manipulated the balance of chaotropic and kosmotropic stressors for the extreme, xerophilic fungi Aspergillus penicilloides and X. bisporus and, via this approach, their established water-activity limits for mycelial growth (∼0.65) were reduced to 0.640. Furthermore, extrapolations indicated theoretical limits of 0.632 and 0.636 a w for A. penicilloides and X. bisporus, respectively. Collectively, these findings suggest that there is a common water-activity limit that is determined by physicochemical constraints for the three domains of life

Structural properties of phosphate-washing waste based geopolymeric mortars

The phosphate ore extraction activities often generate serious environmental problems, particularly those engendered by the phosphate washing waste. The waste was characterized by X ray fluorescence. The powder was calcined at 700 °C. The calcined and uncalcined samples were then investigated by means of X-ray powder diffraction (XRD). The calcined PWW was activated with sodium hydroxide and sodium silicate to produce geopolymeric materials. The reached results prove to reveal that the present phases in the powder appeared to have a remarkable effect on the result of compressive strength

Effects of lanthanide amphoteric incorporation on structural, electrical, and photoluminescence properties of BaTi0.925(Yb0.5Nb0.5)(0.075)O-3 ceramic

International audienceThe influence of the lanthanide incorporation in lead-free ferroelectric BaTi0.925(Yb0.5Nb0.5)(0.075)O-3 (BTYN) perovskite on its structural, dielectric, ferroelectric behavior, piezoelectric and photoluminescence properties was investigated. X-ray diffraction study permitted the identification of an isostructural phase with P4mm-tetragonal symmetry. Praseodymium was found to occupy only Ba-sites instead of the distribution over both sites as in the case of Nd and Eu elements. The improvement of dielectric and ferroelectric properties obtained from Nd- and Eu-phase is discussed in terms of amphoteric behavior effect of these elements. Incorporation of Ln(3+) was found to improve piezoelectric properties from 3 pC/N for BTYN to 18, 40 and 26 pC/N for BTYN:Eu, BTYN:Nd and BTYN:Pr respectively. The photoluminescence (PL) properties of Pr-phase gives rise to the expected electronic transitions associate to Pr3+ ions. In contrast, PL carried out on Eu- and Nd-phases showed dominate strong red emission centered at 690 nm attributed to defect structure and non-stoichiometry. The simultaneous existence of ferroelectric piezoelectric and luminescence properties in the titled system could be promising for electro-optical applications. (C) 2017 Elsevier B.V. All rights reserved

Testicular tumours in prepubertal children: About eight cases

Background: To analyze the spectrum of testicular tumors in prepubertal children and the therapeutic resultants in an unselected population. Materials and Methods: Our hospital database was analyzed for testicular tumors from January 1995 to December 2010 concerning clinical presentation, treatment and therapeutic results. Results: Eight patients were operated on because of testicular tumors.In six cases (75%) the tumor was benign: benign teratoma (four cases), epidermoid cyst (one case) and immature teratoma (one case). Two  patients (25%) had a malignant tumour: yolk-sac tumour (two cases). All this children underwent surgery. Radical inguinal orchidectomy was  performed in six cases and conservative surgery was performed in two cases. One patient has received adjuvant chemotherapy. Followup was uneventfully three years after primary surgery.Conclusion: In prepubertal children, most testicular tumours are benign. If tumour markers were negative testis-preserving surgery can be proposed,  complete excision of the tumour should be ascertained. In the case of testicular teratoma, the possibility of contralateral tumour should be    considered in the follow-up.Key words: Children, Testis, Tumour, Teratoma,yolk-sac tumou

Management of congenital bladder diverticulum in children: A report of seven cases

Background: The purpose of the study is to present theauthor’s experience with congenital bladder diverticulain seven pediatric patients at a developing world tertiarycare center.Materials and Methods: Records of seven patients diagnosed and treated as congenital bladder diverticulum, from January 1998 to December 2009were retrospectively reviewed for age, sex, clinical symptoms, investigative work-up, operative notes, and postoperative follow-up. Results: All patients were males. Age at presentation ranged from six months to six years (mean three years and six months). All were manifested postnatally by urinary tract infection in four cases, bladder retention in three cases and abdominal pain in two cases. Diagnosis was suggested by ultrasound and confi rmed by voiding cystourethrography(VCUG) in all cases and urethrocystoscopy in three cases. Open surgical excision of diverticulum was done in all the patients associated with ureteral reimplantation in four patients with VCUG-documented high-gradevesicoureteral refl ux (VUR). Average follow-up was four years; there is a resolution of symptoms and no diverticulum recurrence at the defi ned mean followup.Conclusion: Recurrent urinary tract infections and voiding dysfunction in pediatric population should always be evaluated for congenital bladder diverticulum. Investigations such as abdominal ultrasound, VCUG and nuclear renal scanning, form an important part of preoperative diagnostic work-up and postoperative follow up. Diverticulectomy with ureteral reimplantation in case of high-grade refl ux, provides good resultswithout recurrence.Key words: Children, congenital bladder diverticulum, diverticulectomy, voiding cystourethrogram, voiding dysfunctio