Superior Interfacial Contact Yields Efficient Electron Transfer Rate and Enhanced Solar Photocatalytic Hydrogen Generation in M/C3N4 Schottky Junctions.

Various literature studies (Table 6) have reported that dispersion of metal nanoparticles (NPs) on graphitic carbon nitride g-C3N4 (M/CN) has considerably improved the photocatalytic hydrogen yield. It is understood that metal NPs create active sites on the surface of CN and act as a cocatalyst. However, the precise changes induced by different metal NPs on the surface of CN still elude us. Here, we report a thorough understanding and comparison of the morphology, metal-support interactions, interfacial charge transfer kinetics, and band characteristics in different M/CN (M = Pt, Pd, Au, Ag, Cu) correlated with photocatalytic activity. Among all metals, Pt/CN was found to be the best performer both under sunlight and UV-visible irradiation. Under sunlight, maximum H2@ 2.7 mmol/h/g was observed over Pt/CN followed by Pd/CN > Au/CN > Ag/CN > Cu/CN ≈ CN. The present study revealed that among all metals, Pt formed superior interfacial contact with g-C3N4 as compared to other metals. The maximum Schottky barrier height (Φb,Pt) of 0.66 V was observed at Pt/CN followed by Φb,Au/CN (0.46 V) and Φb,Pd/CN (0.05 V). The presence of electron-deficient Pt in Pt-XPS, decrease in the intensity of d-DOS of Pt near the Fermi level in VB-XPS, increase in CB tail states, and cathodic shift in Vfb in MS plots sufficiently confirmed strong metal-support interactions in Pt/CN. Due to the SPR effect, Au and Ag NPs suffered from agglomeration and poor dispersion during photodeposition. Finely dispersed Pt NPs (2-4 nm, 53% dispersion) successfully competed with shallow/deep trap states and drove the photogenerated electrons to active metallic sites in a drastically reduced time period as investigated by femtosecond transient absorption spectroscopy. Typically, an interfacial electron transfer rate, KIET,avg, of 2.5 × 1010 s-1 was observed for Pt/CN, while 0.087 × 1010 s-1 was observed in Au/CN. Band alignment/potentials at M/CN Schottky junctions were derived and most favorable in Pt/CN with CB tail states much above the water reduction potential; however, in the case of Pd, these extend much below the H+/H2 potential and hence behave like deep trap states. Thus, in Pd/CN (τ0 = 4200 ps, 49%) and Ag/CN (3870 ps, 53%), electron deep trapping dominates over charge transfer to active sites. The present study will help in designing futuristic new cocatalyst-photocatalyst systems.

Insight into growth of Au-Pt bimetallic nanoparticles: an in situ XAS study.

Au-Pt bimetallic nanoparticles have been synthesized through a one-pot synthesis route from their respective chloride precursors using block copolymer as a stabilizer. Growth of the nanoparticles has been studied by simultaneous in situ measurement of X-ray absorption spectroscopy (XAS) and UV-Vis spectroscopy at the energy-dispersive EXAFS beamline (BL-08) at Indus-2 SRS at RRCAT, Indore, India. In situ XAS spectra, comprising both X-ray near-edge structure (XANES) and extended X-ray absorption fine-structure (EXAFS) parts, have been measured simultaneously at the Au and Pt L3-edges. While the XANES spectra of the precursors provide real-time information on the reduction process, the EXAFS spectra reveal the structure of the clusters formed in the intermediate stages of growth. This insight into the formation process throws light on how the difference in the reduction potential of the two precursors could be used to obtain the core-shell-type configuration of a bimetallic alloy in a one-pot synthesis method. The core-shell-type structure of the nanoparticles has also been confirmed by ex situ energy-dispersive spectroscopy line-scan and X-ray photoelectron spectroscopy measurements with in situ ion etching on fully formed nanoparticles.

Efficacy of anti-scorpion venom serum over prazosin in the management of severe scorpion envenomation.

BACKGROUND: Scorpion venoms cause a massive release of neurotransmitters. Either anti-scorpion venom serum (AScVS) or prazosin has been used in the management of severe scorpion envenomation. AIMS: To compare the time taken for clinical recovery by patients with severe scorpion envenomation after AScVS therapy with that following prazosin therapy. SETTINGS AND DESIGN: A prospective, open-labeled clinical trial was undertaken to compare the effects of the AScVS and/or prazosin on clinical recovery in scorpion-stung patients. MATERIALS AND METHODS: Eighty-one patients from rural districts of Maharashtra presenting with severe scorpion envenomation were assigned to three treatment groups (AScVS: n = 28; prazosin: n = 25; AScVS + prazosin: n = 28). Severity of scorpion envenomation was graded using a proposed composite clinical scoring system to assess the therapeutic efficacy. AScVS was administered as an intravenous slow bolus, ranging from 40 to 100 ml, depending on the severity of envenomation. Prazosin was given as 1 mg every 3 h. STATISTICAL ANALYSIS USED: The non-parametric "Kruskal-Wallis" test was used in the statistical analysis and a P-value of 0.05 was considered significant. RESULTS: Mean composite scores of patients from the three groups at the time of admission were comparable. Complete clinical recovery was noted in 4.14 ± 1.6 h and 19.28 ± 5.03 h in the subjects who were administered AScVS and prazosin, respectively (P < 0.001). There was no incidence of anaphylactic reaction to AScVS. CONCLUSIONS: Intravenous slow bolus of AScVS given based on the clinical severity of envenomation leads to early recovery than prazosin alone and is well tolerated.

Influence of timing on performance of laparoscopic cholecystectomy for acute biliary pancreatitis.

AIM: Gallstone disease is the most common cause of acute pancreatitis. Cholecystectomy is mandatory to avoid recurrence of pancreatitis. Our objective was to evaluate the results of laparoscopic cholecystectomy (LC) in patients with gall-stone induced pancreatitis. METHODS: All patients presenting to us within the time frame from February 2004 to June 2008 with acute biliary pancreatitis were included in the study. The severity of pancreatitis was assessed by Ranson's criteria. ERCP and endoscopic sphincterotomy was performed when the common bile duct (CBD) was dilated (>6 mm) with either calculi or sludge as seen on imaging. Patients with successful ERCP with predicted demanding laparoscopic cholecystectomy were discharged instead for an elective LC, 4-6 weeks later. Patients with mild pancreatitis (with Ranson's score of 3 or less) and predicted uncomplicated LC underwent surgery at the same admission. The difficulty of the procedure was determined by the presence of adhesions in the gallbladder area, dissection in Calot's triangle, tackling the dilated cystic duct, intra-operative bleeding, and the need for a drain. RESULTS: A total of 26 patients (12 male and 14 female; age range 23-75 years) with acute biliary pancreatitis comprised the study group. Eleven patients with suspected choledocholithiasis underwent ERCP and clearance of the CBD was done in all of them. Nine patients (2 ERCP and 7 non-ERCP) underwent early LC in the same admission. Seventeen patients (9 ERCP and 8 non-ERCP) were predicted as difficult cases for LC and underwent delayed LC. No patient had recurrent pancreatitis in the interval period. CONCLUSION: There was no significant difference in the operative difficulty between early and delayed LC when patients were selected for timing of LC based on pre-defined criteria.

Magnetic behavior of nanocrystalline ErCo(2).

We have investigated the magnetic behavior of the nanocrystalline form of a well-known Laves phase compound, ErCo(2)-the bulk form of which has been known to undergo an interesting first-order ferrimagnetic ordering near 32 K-synthesized by high-energy ball-milling. It is found that, in these nanocrystallites, Co exhibits ferromagnetic order at room temperature, as inferred from the magnetization data. However, the magnetic transition temperature for the Er sub-lattice remains essentially unaffected suggesting the (Er)4f-Co(3d) coupling is weak on Er magnetism. The net magnetic moment as measured at high fields, for example at 120 kOe, is significantly reduced with respect to that for the bulk in the ferrimagnetically ordered state and possible reasons are outlined for this. We have also compared the magnetocaloric behavior for the bulk and for nanoparticles.

Varied presentations of gastrointestinal stromal tumour.

Gastrointestinal stromal tumours (GIST) are soft tissue tumours arising from the mesenchyma in the gastrointestinal tract. These are rare tumours. However, over the past few years with the better understanding of the pathogenesis of GIST and better imaging facilities, the diagnosis is made more frequently. The characteristic diagnostic feature of GIST is the expression of CD34 and receptor tyrosine kinase KIT, CD117 by these tumours. The use of tyrosine kinase inhibitor imatinib mesylate has led to improved outcome. The presentation of GIST however remains non-specific, and varies depending upon the size and the organ of origin. We present a series of four cases of GIST with varied presentation.

Spectrum and outcome of pancreatic trauma.

BACKGROUND AND AIMS: Pancreatic trauma is associated with high morbidity and mortality. Diagnosis is often difficult and surgery poses a formidable challenge. METHOD: Data from 17 patients of pancreatic trauma gathered from a prospectively maintained database were analysed and the following parameters were considered: mode of injury, diagnostic modalities, associated injury, grade of pancreatic trauma and management. Pancreatic trauma was graded from I through IV, as per Modified Lucas Classification. RESULTS: The median age was 39 years (range 19-61). The aetiology of pancreatic trauma was blunt abdominal trauma in 14 patients and penetrating injury in 3. Associated bowel injury was present in 4 cases (3 penetrating injury and 1 blunt trauma) and 1 case had associated vascular injury. 5 patients had grade I, 3 had grade II, 7 had grade III and 2 had grade IV pancreatic trauma. Contrast enhanced computed tomography scan was used to diagnose pancreatic trauma in all patients with blunt abdominal injury. Immediate diagnosis could be reached in only 4 (28.5%) patients. 7 patients responded to conservative treatment. Of the 10 patients who underwent surgery, 6 required it for the pancreas and the duodenum. (distal pancreatectomy with splenectomy-3, pylorus preserving pancreatoduodenectomy-1, debridement with external drainage-1, associated injuries-duodenum-1). Pancreatic fistula, recurrent pancreatitis and pseudocyst formation were seen in 3 (17.05%), 2 (11.7%) and 1 (5.4%) patient respectively. Death occurred in 4 cases (23.5%), 2 each in grades III and IV pancreatic trauma. CONCLUSIONS: Contrast enhanced computed tomography scan is a useful modality for diagnosing, grading and following up patients with pancreatic trauma. Although a majority of cases with pancreatic trauma respond to conservative treatment, patients with penetrating trauma, and associated bowel injury and higher grade pancreatic trauma require surgical intervention and are also associated with higher morbidity and mortality.

Brain abscess following esophageal dilatation.

The authors report a case of brain abscess following esophageal dilatation for corrosive stricture in a 23-year-old woman. High fever and neurological findings post dilatation led us to suspect this rare complication, which was confirmed by cranial computed tomography. Prompt treatment with antibiotics and surgical drainage led to a favorable clinical outcome. This serious complication should be kept in mind when long-term treatment of corrosive stricture by repeated esophageal dilatation is planned. Prior cases of brain abscess following esophageal dilatation are reviewed.

Clinico-pathological follow-up after total colectomy and straight ileo-anal anastomosis done for ulcerative colitis.

BACKGROUND: Restorative proctocolectomy is used as surgical treatment for ulcerative colitis. We have earlier documented adaptative changes in the terminal ileum after total colectomy, and straight ileo-anal anastomosis. AIM: To correlate the morphologic and functional changes in the ileal mucosa after total colectomy and hand-sewn straight ileo-anal anastomosis for ulcerative colitis. METHODS: Thirty consecutive patients (age range 15-50 years, 24 men) who had undergone total colectomy, rectal mucosectomy and hand-sewn straight ileo-anal anastomosis for ulcerative colitis were included in the study. These patients were followed up at 3-monthly intervals following surgery for two years and later once every year for a median duration of 9.5 (range 1-17) years. The clinical parameters studied were weight gain, frequency of stools, nature of stools, nocturnal stool frequency and need for antidiarrheal drugs. At each follow-up visit they were subjected to per rectal ileoscopy with ileal biopsy and barium enema. Ileal biopsy was analyzed histologically and histochemically. RESULTS: The clinical features improved over time, with average weight gain of 5 (range 1-7) Kg at one year. Frequency of stools decreased from 8-10 per day to 2-3 per day. The stools became semisolid and there was no need for antidiarrheal drug by the end of one year. All the patients showed adaptative changes in the ileum. The ileal mucosa was completely transformed into colonic type by the end of one year, colonoscopically (spacious lumen characteristic of colon), radiologically (disappearance of ileal characteristics with rectosigmoid-like appearance), histologically (blunting of villi with increase in goblet cells), and histochemically (sialomucin pattern to sulfomucin pattern). CONCLUSIONS: The ileum undergoes adaptative changes with corresponding improvement of clinical parameters over time, after proctocolectomy and ileoanal anastomosis for ulcerative colitis.

Nonfunctioning islet cell tumor presenting with ascites and portal hypertension.

Nonfunctioning islet cell tumors commonly cause no symptoms. A 22-year-old woman presented with lump in the left hypochondrium, refractory high-protein ascites and evidence of left-sided portal hypertension. At exploratory laparotomy, a 30 cm x 15 cm mass was seen at the splenic hilum, with large collateral vessels around. Distal pancreatectomy with splenectomy was done. Histology of the mass showed malignant islet cell tumor infiltrating the spleen. The patient died in the postoperative period.

Self-bougienage: long-term relief of corrosive esophageal strictures.

BACKGROUND: Corrosive esophageal strictures require dilatation at frequent intervals. OBJECTIVE: To determine the efficacy of self-dilatation in treatment of corrosive esophageal strictures. METHODS: Retrospective analysis of data from 51 patients with corrosive esophageal strictures seen in a surgical unit. Eighteen patients underwent per-oral antegrade dilatation of stricture using gum elastic bougies (Group I); 15 patients underwent retrograde dilatation with endless string using an India rubber dilator devised at the authors' institution, followed by per-oral antegrade dilatation (Group II); 15 patients underwent retrograde dilatation followed by antegrade dilatation with endless string through esophagostomy (Group III). In three patients with stricture of the entire esophagus, endless string could not be passed; they were subjected to esophagocoloplasty. All patients were taught self-dilatation with gum elastic bougies as the final step, and were put on a progressive, domiciliary, self-dilatation program. Quarterly follow up was done for one year, to ascertain whether self-bougienage was being performed properly. RESULTS: All patients responded well to treatment, with significant relief of dysphagia and improvement in health and barium study findings. Six patients developed mediastinitis (3, 2 and 1 in Groups I, II and III, respectively) during initial dilatation; all improved with conservative management. Only one patient who failed to carry out self-bougienage had to be readmitted and retrained in the procedure, after which he remained asymptomatic. CONCLUSIONS: Patients with corrosive esophageal strictures can be treated with a long-term self-bougienage program, which avoids the need for frequent hospital admissions for esophageal dilatation.

Cholecystoduodenoplasty for high-output duodenal fistula.

External duodenal fistulae from sutured duodenal ulcer perforation sites are difficult to manage and most patients succumb to septicemia and undernutrition. This is due to failure of closure of the perforation site in the duodenum. Most techniques described in the past to facilitate closure have failed to give satisfactory results. We have devised a new procedure where the duodenal ulcer perforation is closed by mobilizing the gall bladder. A hole is made in the fundus of the gall bladder and it is anastomosed to the freshened edges of the duodenal opening. We have treated six patients by this technique. In five patients the leak was satisfactorily sealed. Three patients died - one due to persistent leak and two due to jejunostomy leak.

Laparoscopic cholecystectomy in patient with portal cavernoma and portal hypertension.

Successful laparoscopic cholecystectomy has been reported in patients with cirrhosis of liver with portal hypertension; the procedure has, however, not been reported in patients with portal vein thrombosis, portal cavernoma and portal hypertension. We report an 18-year-old man with portal hypertension due to portal vein thrombosis and portal cavernoma who had symptomatic gallstone disease and was successfully treated with laparoscopic cholecystectomy.

Laparoscopic management of hydatid cyst of liver.

We describe the laparoscopic excision of a hydatid cyst in the liver. During the procedure, done after treatment with the scolicidal agents praziquantel and albendazole, care was taken to prevent spillage of scolices during evacuation of contents and to excise the entire germinal epithelium. The patient had no immediate or short-term complications and is asymptomatic 3 months later.

Leech therapy for complicated varicose veins.

Several methods of limb bandaging have been described to reduce the oedema and enhance ulcer healing in complicated varicose veins, with varying success rates. Leech therapy has never before been tried for the same. We evaluated the effectiveness of medicinal leech therapy in producing venous decongestion, reversal of oedema, hyperpigmentation and healing of varicose ulcer(s). Whether the leech selectively sucks venous blood was also investigated. Hirudo medicinalis (medicinal leech) was applied to the area surrounding the varicose ulcer(s) in 20 patients with varicose veins with complications and the patients monitored for ulcer healing, and decrease in hyperpigmentation, oedema and limb girth. The partial pressure of O2 (pO2) of 7 patients' arterial and venous blood was compared to that sucked by the leech. After leech therapy all the ulcers showed healing, while 95 per cent of patients showed a decrease in oedema and limb girth. Seventy five per cent patients demonstrated a decrease in hyperpigmentation. The mean pO2 of blood sucked by the leech was 40.05 +/- 7.24 mmHg, which was similar to the mean pO2 of the patients' venous blood (34.33 +/- 8.4 mmHg). Thus it appears from this study that the medicinal leech sucks venous blood and aids ulcer healing, and can probably therefore be used as an effective adjunct in the management of complicated varicose veins. This however requires further evaluation by controlled trials.

Mesenteric vasculopathy in intestinal tuberculosis.

BACKGROUND: Involvement of mesenteric vessels in intestinal tuberculosis and its role in the pathogenesis of the intestinal changes have not been studied histologically. AIM: To study mesenteric vessels in patients undergoing surgery for complications of intestinal tuberculosis. METHODS: Resected intestinal specimens from 68 patients presenting with intestinal perforation and intestinal obstruction were examined; involvement of the major mesenteric vessels was evaluated. RESULTS: Granulomas were seen in the vessel wall in one case and near the vessel wall in 11 cases, intraluminal thrombi were seen in 23 cases, and subintimal fibrosis in nine cases. Perivascular cuffing was seen in intramural and subserosal vessels in ten cases. CONCLUSIONS: Changes in the vessel wall may lead to gut ischemia, which may contribute to the development of strictures and stercoral perforation in intestinal tuberculosis.

Adult intrahepatic solitary choledochal cyst.

A 20-year-old woman presented with dull ache in the abdomen. Ultrasonography and CT scan showed a solitary liver cyst. Roux-en-Y cystojejunostomy was done since there was bile in the cyst. Histology of the cyst wall revealed it to be a choledochal cyst. Solitary intrahepatic choledochal cyst and presentation in adult life are rare.

Ksharsootra (medicated seton) treatment for fistula-in-ano.

BACKGROUND: Recurrence and incontinence are common after conventional surgery for fistula-in-ano. Medicated seton (ksharsootra) is a time-tested therapy. METHODS: Seton treatment was given to 114 patients with anal fistulae. The initial loose seton was changed weekly to achieve fistulotomy. RESULTS: Application of non-medicated seton did not show any cutting action; hence all patients were treated with ksharsootra after 3 weeks. Anal discharge (n = 114) and burning pain (35) were noted in the first 48-72 hours. The cut-out rate was around 1 cm/week, with mean cut-out time 8.3 weeks (range 3-18). All wounds healed well and patients remained ambulatory. Local induration developed in 18 patients; four had an abscess. There was no incontinence or recurrence over a follow-up of 6 months to 2 1/2 years. CONCLUSIONS: Ksharsootra treatment for anal fistulae is safe and effective, with low complication rates.