Investigation of the reactivity of AlCl3 and CoCl2 toward molten alkali-metal nitrates in order to synthesize CoAl2O4

Cobalt aluminate CoAl2O4 powder, constituted of nano-sized crystallites, is prepared, involving the reactivity of AlCl3 and CoCl2 with molten alkali-metal nitrates. The reaction at 450 °C for 2 h leads to a mixture of spinel oxide Co3O4 and amorphous γ-Al2O3. It is transformed into the spinel oxide CoAl2O4 by heating at 1000 °C. The powders are mainly characterized by XRD, FTIR, ICP, electron microscopy and diffraction, X-EDS and diffuse reflection. Their properties are compared to those of powders obtained by solid state reactions of a mechanical mixture of chlorides or oxides submitted to the same thermal treatment

Fungal peritonitis in Iranian children on continuous ambulatory peritoneal dialysis: a national experience.

INTRODUCTION. Fungal peritonitis (FP), causing catheter obstruction, dialysis failure, and peritoneal dysfunction, is a rare but serious complication of peritoneal dialysis. In this study, the frequency and risk factors of FP are evaluated in children who underwent peritoneal dialysis. MATERIALS AND METHODS. A retrospective multicenter study was performed at the 5 pediatric peritoneal dialysis centers in Iran from 1971 to 2006, and FP episodes among 93 children were reviewed. Risk ratios were calculated for the clinical and demographic variables to determine the risk factors of FP. RESULTS. Ninety-three children aged 39 months on average were included in study. Sixteen out of 155 episodes of peritonitis were fungi infections, all by Candida albicans. The risk of FP was higher in those with relapsing bacterial peritonitis (P = .009). Also, all of the patients had received antibiotics within the 1 month prior to the development of FP. Catheters were removed in all patients after 1 to 7 days of developing FP. Six out of 12 patients had catheter obstruction and peritoneal loss after the treatment and 5 died due to infection. CONCLUSIONS. Fungal peritonitis, accompanied by high morbidity and mortality in children should be reduced by prevention of bacterial peritonitis. Early removal of catheter after recognition of FP should be considered

Fungal peritonitis in Iranian children on continuous ambulatory peritoneal dialysis: a national experience.

INTRODUCTION. Fungal peritonitis (FP), causing catheter obstruction, dialysis failure, and peritoneal dysfunction, is a rare but serious complication of peritoneal dialysis. In this study, the frequency and risk factors of FP are evaluated in children who underwent peritoneal dialysis. MATERIALS AND METHODS. A retrospective multicenter study was performed at the 5 pediatric peritoneal dialysis centers in Iran from 1971 to 2006, and FP episodes among 93 children were reviewed. Risk ratios were calculated for the clinical and demographic variables to determine the risk factors of FP. RESULTS. Ninety-three children aged 39 months on average were included in study. Sixteen out of 155 episodes of peritonitis were fungi infections, all by Candida albicans. The risk of FP was higher in those with relapsing bacterial peritonitis (P = .009). Also, all of the patients had received antibiotics within the 1 month prior to the development of FP. Catheters were removed in all patients after 1 to 7 days of developing FP. Six out of 12 patients had catheter obstruction and peritoneal loss after the treatment and 5 died due to infection. CONCLUSIONS. Fungal peritonitis, accompanied by high morbidity and mortality in children should be reduced by prevention of bacterial peritonitis. Early removal of catheter after recognition of FP should be considered

Jet-nozzle method for measuring response times of scalar sensors used in liquids and gases

Response time is a central characteristic of sensors measuring solute concentrations. Knowing the response time of the sensor under realistic conditions is critically important when measuring rapid changes, e.g., oxygen concentration fluctuations for aquatic eddy covariance flux calculations. Response times therefore should be determined under conditions that are similar to those the sensor is exposed to when deployed for the actual measurements. This study introduces a new method for quantifying the response time of mini- or microsensors measuring solute concentrations in liquids and gases. The method is based on the rapid switching of the supply of two fluids with different oxygen concentration to the sensor without removing the sensor from the fluid flow. The device uses a jet nozzle moved by electromagnetic actuators, and the switching of the calibration fluids is monitored by a reference sensor with a response time < 0.001 s. The functionality of the device is demonstrated for a fast oxygen optode system that consisted of a fiber minioptode connected to an oxygen meter that was read by a data logger. With the setup described here, the method permits reproducible response time measurements with a resolution of 0.01 s +/- 0.001 s (SD, n = 60). With this technique, the response time characterization of aquatic sensors can be standardized

Pediatric renal neoplasms (A clinicopathological study in pathology departments of Dr Sheikh children hospital and Imam Reza hospital in Mashhad during 15 years)

Background&Objective: Pediatric renal tumors represent approximately 7% of all childhood cancers and are completely different from those occurring in adults. The aim of this study was to make an analysis of clinical and pathological characteristics of these tumors. Materials&Methods: In this descriptive study all of the pediatric patients diagnosed as having renal neoplasm in departments of pathology of Dr Sheikh children hospital and Imam Reza hospital from 1991-2006 were evaluated. Results: 52 patients including 27 boys and 25 girls with mean age of 40.63 months were studied. Tumors involved each kidney in 24 (45.3%) and were bilateral in 5 (9.4%) patients. Abdominal mass was the commonest clinical symptom and sign. Congenital anomalies were presented in 6 (14.6%) patients. Histopathological examination showed Wilms tumor in 46 (86.8%), cystic partially differentiated nephroblastoma in 2 (3.8%), mesoblastic nephroma in 2 (3.8%) rhabdoid tumor of the kidney in 1 (1.9%), metanephric adenofiroma and low-grade tubulopapillary carcinoma in 1 (1.9%) and clear cell sarcoma of the kidney in 1 (1.9%) patient. 11 (20.8%) cases were in stage I, 16 (30.2%) stage II, 13 (24.5%) stage III, 8 (15.1%) stage IV and 5 (9.4%) stage V. Conclusion: Although Wilms tumor is the commonest renal neoplasm in childhood there are also recently described entities such as metanephirc tumors and juvenile renal carcinoma that must be considered in histopathological evaluation of a pediatric renal neoplasm. Role of molecular and cytogenetic methods is increasing for classification and treatment of childhood renal neoplasms

XAS and GIXRD Study of Co Sites in CoAl2O4 Layers Grown by MOCVD

The chemical environment of Co sites in CoAl2O4 layers grown by metal-organic chemical vapor deposition has been investigated by X-ray absorption spectroscopy (XAS) and X-ray diffraction (XRD). It is shown that the air- or [O2 + H2O]-annealing at 500 °C of the layers deposited at low temperature induce a partial crystallization with the formation of (Co1-2ηAl2)(Co2Al2η)(Co 2ηAl2(1-η)))O4 spinel (η = 0.2-0.27). Nevertheless, slightly more than half of Co remains in an amorphous phase, and XAS data are consistent with the formation of a medium-range ordered Co3O4 phase, especially upon air-annealing. Layers grown at higher temperatures (600-650 °C) exhibit a similar but more complex structure, since the presence of an additional medium-range ordered phase (likely, CoAl2O4) is also revealed. The air-annealing at high temperature (800 °C) generates blue, almost completely crystalline, CoAl2O4 layers. Optical properties of deposited layers are discussed by referring to the outcomes of structural results. In particular, the optical absorption spectrum results negligibly affected by the presence of the amorphous phase, while absorptions present in the 300-500 nm range, responsible for the green layer color and evident in samples annealed in an oxidizing atmosphere or grown at high temperature, are likely caused by the octahedrally coordinated Co ions of the partially inverted spinel (Co;- 2ηAl2η)(Co2(1-η)Al 2(1-η))O4 -))O4 phase. Despite the XRD analysis that ultimately demonstrates the presence of octahedrally coordinated Co ions, whose oxidation state in the spinel phase is in majority Co(II), the occurrence of Co(III) species with an octahedral environment cannot be ruled out