Photocatalytic parameters and kinetic study for degradation of dichlorophenol-indophenol (DCPIP) dye using highly active mesoporous TiO2 nanoparticles.

Highly active mesoporous TiO2 of about 6nm crystal size and 280.7m(2)/g specific surface areas has been successfully synthesized via controlled hydrolysis of titanium butoxide at acidic medium. It was characterized by means of XRD (X-ray diffraction), SEM (scanning electron microscopy), TEM (transmission electron microscopy), FT-IR (Fourier transform infrared spectroscopy), TGA (thermogravimetric analysis), DSC (differential scanning calorimetry) and BET (Brunauer-Emmett-Teller) surface area. The degradation of dichlorophenol-indophenol (DCPIP) under ultraviolet (UV) light was studied to evaluate the photocatalytic activity of samples. The effects of different parameters and kinetics were investigated. Accordingly, a complete degradation of DCPIP dye was achieved by applying the optimal operational conditions of 1g/L of catalyst, 10mg/L of DCPIP, pH of 3 and the temperature at 25±3°C after 3min under UV irradiation. Meanwhile, the Langmuir-Hinshelwood kinetic model described the variations in pure photocatalytic branch in consistent with a first order power law model. The results proved that the prepared TiO2 nanoparticle has a photocatalytic activity significantly better than Degussa P-25.

Cryptosporidium gastroenteritis in Egyptian children with acute lymphoblastic leukemia: magnitude of the problem.

PURPOSE: Cryptosporidium species is considered to be an important cause of significant morbidity in immunocompromised individuals. A prospective case-control study of sporadic diarrhea due to Cryptosporidium infection was conducted on children with acute lymphoblastic leukemia (ALL). METHODS: Forty children with ALL on maintenance chemotherapy according to the Berlin-Frankfurt-Munster (BFM-90) protocol and 45 sex- and age-matched controls were studied. The ALL group included 25 patients with acute diarrhea and 15 without diarrhea, and the control group included 30 children with acute diarrhea and 15 without. Collected stool specimens were examined using modified Ziehl-Neelsen (MZN) and modified trichrome stains. Serum Cryptosporidium Parvum immunoglobulin G (IgG) antibodies were detected by enzyme-linked immunosorbent assay. RESULTS: Cryptosporidium oocysts, pathogenic Gram-negative organisms, Giardia lamblia, and Entamoeba histolytica were identified in the stool samples (fecal specimens) of six (24%), eight (32%), four (16%), and two (8%), respectively, of the 25 patients with ALL and actute diarrhea and in one (3%), two (6.5%), six (20%), and five (16.5%), respectively, of the 30 control patients with diarrhea. Serum IgG antibodies were positive in four of the six ALL patients and in one of the control group patients with Cryptosporidium diarrhea who tested positive for oocysts in the stool. Diarrhea duration and severity were greater in ALL patients with stool-positive Cryptosporidium oocysts than in those with non-Cryptosporidium-positive diarrhea (p < 0.000). CONCLUSIONS: Cryptosporidium infection should be considered in children with ALL presenting with prolonged or severe watery diarrhea during chemotherapy, especially those treated with methotrexate and 6-mercaptopurine. Since Cryptosporidium is not routinely tested for in stool examination, a MZN stain is recommended.