Ta2 Ni3 Se8 : 1D van der Waals Material with Ambipolar Behavior.

In this study, high-purity and centimeter-scale bulk Ta2 Ni3 Se8 crystals are obtained by controlling the growth temperature and stoichiometric ratio between tantalum, nickel, and selenium. It is demonstrated that the bulk Ta2 Ni3 Se8 crystals could be effectively exfoliated into a few chain-scale nanowires through simple mechanical exfoliation and liquid-phase exfoliation. Also, the calculation of electronic band structures confirms that Ta2 Ni3 Se8 is a semiconducting material with a small bandgap. A field-effect transistor is successfully fabricated on the mechanically exfoliated Ta2 Ni3 Se8 nanowires. Transport measurements at room temperature reveal that Ta2 Ni3 Se8 nanowires exhibit ambipolar semiconducting behavior with maximum mobilities of 20.3 and 3.52 cm2 V-1 s-1 for electrons and holes, respectively. The temperature-dependent transport measurement (from 90 to 295 K) confirms the carrier transport mechanism of Ta2 Ni3 Se8 nanowires. Based on these characteristics, the obtained 1D vdW material is expected to be a potential candidate for additional 1D materials as channel materials.

Choledochorraphy (primary repair) versus t-tube drainage after open choledochotomy.

BACKGROUND: T-tube drainage used to be standard practice after surgical choledochotomy, but there is now a tendency in some canters to close the common bile duct primarily. This study was designed to compare the clinical results of primary closure with T-tube drainage after open choledocotomy and assess the safety of primary closure for future application. METHODS: This study was conducted at surgical Unit-3, ward 26 Jinnah Postgraduate Medical Centre Karachi, from January 2007 to January 2008. Forty patients were included in this study out of which 20 underwent primary closure and 20 T-tube placements. It was Quasi-experimental, non-probability, purposive sampling. Main outcome measures were operating time, duration of hospital stay, and postoperative complications. SPSS-10 was used for data analysis. RESULTS: The age of patients in the study ranged from 29-83 years. There were 3 male while 37 female patients. Group-1 consisted of 20 patients underwent primary closure after choledocotomy, while Group-2 also consisted of 20 patients underwent T-tube drainage after duct exploration. Mean hospital stay in Group-1 patients was 7.63 days while in group 2 it was 13.6 days. Overall complication rate in group 1 was 15%, biliary leakage in 1 (5%), jaundice in 1 (5%), wound infection in 1 (5%). No re-exploration was required in Group-1. In Group-2 overall complication rate was 30%, biliary leakage in 2 (2%), jaundice in 1 (5%), dislodgement of T-tube in 1 (5%), wound infection in 1 (5%), and sepsis in 1 (5%) patients. Re-exploration was done in one patient. CONCLUSION: Primary closure of Common Bile Duct (CBD) is a safe and cost-effective alternative procedure to routine T-tube drainage after open choledocotomy.

High Breakdown Current Density in Quasi-1D van der Waals Layered Material Ta2NiSe7.

We synthesized ternary composition chalcogenide Ta2NiSe7, a quasi-one-dimensional (Q1D) material with excellent crystallinity. To utilize the excellent electrical conductivity property of Ta2NiSe7, the breakdown current density (JBD) according to thickness change through mechanical exfoliation was measured. It was confirmed that as the thickness decreased, the maximum breakdown voltage (VBD) increased, and at 18 nm thickness, 35 MA cm-2 of JBD was measured, which was 35 times higher than that of copper, which is commonly used as an interconnect material. By optimization of the exfoliation process, it is expected that through a theoretical model fitting, the JBD can be increased to about 356 MA cm-2. It is expected that the low-dimensional materials with ternary compositions proposed through this experiment can be used as candidates for current-carrying materials that are required for the miniaturization of various electronic devices.

Mini-cholecystectomy: a feasible option.

BACKGROUND: In standard or conventional cholecystectomy gallbladder is approach through a subcostal incision of 7-10 Cm. New technique and procedures have evolved, aiming at decreased tissue damage, pain, hospital stay and complications. This study was conducted to assess cholecystectomy through 5 Cm mini-laparotomy. METHODS: This study was conducted at Department of General Surgery, Ward-26, Jinnah Postgraduate Medical Centre, Karachi from January, 2008 to January, 2009. Both sexes irrespective of age were included in this study. Ninety cases were females and 10 were male. Mean age of the patients was 48 years. Mini-cholecystectomy was performed on patients and results evaluated as percent and frequency. RESULTS: This study included 100 patients with cholelithiasis. Mini-cholecystectomy was possible in 95% cases, and in 5 cases incision had to be extended to conventional cholecystectomy. The average operating time was 50 minutes and postoperative hospital stay was 2-days and postoperative complications like minor biliary leal haemorrhage and wound infection was seen in 10 cases. CONCLUSION: Mini-cholecystectomy is a safe procedure with shorter operative time, fewer complications, better prognosis, and less of postoperative hospital stay. It may be recommended as a procedure of choice where laparoscopic facilities are not available.

Open versus closed method of establishing pneumoperitoneum for laparoscopic cholecystectomy.

OBJECTIVE: To compare the efficacy and safety of the Hasson cannula (open) and Veress needle (closed) method to gain access in the abdominal cavity for laparoscopic cholecystectomy. STUDY DESIGN: Randomized controlled study. PLACE AND DURATION OF STUDY: Ward 26, Jinnah Postgraduate Medical Centre, Karachi, from January to December 2007. METHODOLOGY: All patients undergoing laparoscopic cholecystectomy during the study period were enrolled. Younger (< 20 years) and elderly (> 65 years) patients and those with co-morbid conditions were excluded. The remaining were randomized into two study groups. In one group, the Hasson cannula was used, while in the other Veress needle was used to establish pneumoperitoneum. Surgeries were performed by experienced surgeons of the ward. Variables comparing the safety and efficacy of the two methods were studied. RESULTS: There were a total of 60 patients in each group. In the Hasson cannula group 15 (25%) had complications of gas leakage, one developed a port-site hematoma and two patients developed wound infections. No complications occurred in the Veress needle arm. The mean access time in the Hasson cannula group (4.6+/-1.1 minutes) was less than that of for the Veress needle arm (5.4+/-0.7 minutes). Complications of visceral or vascular injury, port-site hernia or gas embolism did not occur in either arm. CONCLUSION: Although complications occurred using the Veress needle technique, the Hasson cannula technique was faster. Further studies on larger sample sizes are necessary to establish corroborative evidence and formulate guidelines.

Mortality in necrotizing fasciitis.

OBJECTIVE: The objective of this study was to determine the mortality rate in patients presenting with Necrotizing Fasciitis. This prospective study was conducted at ward 26, JPMC Karachi over a period of two years from March 2001 to Feb 2003. METHODS: All patients above the age of 12 years diagnosed to be having Necrotizing Fasciitis and admitted through the Accident and emergency department were included in this study. After resuscitation, the patients underwent the emergency exploration and aggressive surgical debridement. Post-operatively, the patients were managed in isolated section of the ward. The patients requiring grafting were referred to plastic surgery unit. The patients were followed up in outpatients department for about two years. RESULTS: Over all, 25 male and 5 female patients fulfilled the inclusion criteria and were included in this study. The common clinical manifestations include redness, swelling, discharging abscess, pain, fever, skin necrosis and foul smelling discharge etc. The most common predisposing factor was Diabetes mellitus whereas the most commonly involved site was perineum. All patients underwent aggressive and extensive surgical debridements. The common additional procedures included Skin grafting, Secondary suturing, Cystostomy and Orchidectomy. Bacteroides and E. coli were the main micro-organisms isolated in this study. Bacteroides was the most common microorganism isolated among the eight patients who died. CONCLUSION: Necrotizing Fasciitis is a potentially life threatening emergency condition and carries the mortality rate of about 26.6%. The major contributing factors to increase the mortality missed initially diagnosed, old age, diabetes mellitus truncal involvement and late presentation. Anorectal involvement of disease carry worse prognosis. Hyperbaric oxygen therapy and proper use of unprocessed honey reduced the mortality rate.

Effect of route of buprenorphine on recovery and postoperative analgesic requirement in paediatric patients.

BACKGROUND: We compared the effects of extradural with intravenous (i.v.) buprenorphine on postoperative pain and recovery characteristics. METHODS: Thirty patients, aged 11-13 years, who were undergoing inguinal hernia repair with or without orchidopexy, were randomly allocated to receive either caudal 0.5% bupivacaine alone (group A) or were additionally given i.v. buprenorphine 2.5 micro g.kg-1 (group B) or caudal buprenorphine in the same dose (group C). Patients were followed for 8 h after the end of surgery. RESULTS: All patients remained haemodynamically stable during the study period and no clinical respiratory depression was seen. Nausea, vomiting, urinary retention and pruritus were more common in the extradural buprenorphine group. Three patients in group A, five in group B and eight in group C did not require any additional analgesia during the study period. The incidence of vomiting was 20%, 50% and 80% in groups A, B and C, respectively. Four patients in group C had urinary retention compared with one each in the other two groups. CONCLUSIONS: Administration of buprenorphine resulted in a higher incidence of side-effects.