A retrospective evaluation of 200 consecutive recipients of autologous peripheral blood stem cell transplantation (PBSCT) was conducted to ascertain the incidence and outcome of infection with Clostridium difficile. The diagnosis was confirmed in 14 patients with diarrhea (15 episodes) at a median of 33 days after stem cell infusion. Five patients were neutropenic at the time of diagnosis. Every individual had adverse known risk factors such as recent or current use of antibiotic, corticosteroid and antiviral therapy, recent administration of myeloablative chemotherapy and numerous, prolonged periods of hospitalization. Diarrhea, frequently hemorrhagic, was the most common presenting feature along with fever, abdominal cramps and abdominal distention. Diagnosis was established by the stool-cytotoxin test. Response to standard treatment with oral vancomycin or metronidazole was prompt despite the presence of several adverse prognostic features in these patients. There was only one instance of relapse which was also treated successfully. Several transplant-related variables such as age, sex, underlying malignancy, myelo-ablative regimen, duration of neutropenia, and prophylactic use of oral ampicillin underwent statistical analysis but failed to be predictive of C. difficile infection in such a setting. Finally, C. difficile is not uncommon after autologous PBSCT and must be included in the differential diagnosis in any such patient with diarrhea.

Photocatalytic materials for photocatalysis is recently proposed as a promising strategy to address environmental remediation. Metal-free graphitic carbon nitride (g-C 3 N 4 ), is an emerging photocatalyst in sulfate radical based advanced oxidation processes. The solar-driven electronic excitations in g-C 3 N 4 are capable of peroxo (O-O) bond dissociation in peroxymonosulfate/peroxydisulfate (PMS/PDS) and oxidants to generate reactive free radicals, namely SO 4•− and OH • in addition to O 2 •− radical. The synergistic mechanism of g-C 3 N 4 mediated PMS/ PDS photocatalytic activation, could ensure the generation of OH • radicals to overcome the low reductive potential of g-C 3 N 4 and fastens the degradation reaction rate. This article reviews recent work on heterojunction formation (type-II heterojunction and direct Z-scheme) to achieve the bandgap for extended visible light absorption and improved charge carrier separation for efficient photocatalytic efficiency. Focus is placed on the fundamental mechanistic routes followed for PMS/PDS photocatalytic activation over g-C 3 N 4 -based photocatalysts. A particular emphasis is given to the factors influencing the PMS/PDS photocatalytic activation mechanism and the contribution of SO 4 •− and OH • radicals that are not thoroughly investigated and require further studies. Concluding perspectives on the challenges and opportunities to design highly efficient persulfateactivated g-C 3 N 4 based photocatalysts toward environmental remediation are also intensively highlighted.

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