Performance Analysis of an α-Graphyne Nano-Field Effect Transistor.

Graphyne has attractive electronic properties that make it a possible replacement of silicon in FET technology. In FET technology, the goal is to achieve low power dissipation and lower subthreshold swing. In this study, we focused on achieving these goals and studied the electronic properties of α-graphyne nanoribbons. We simulated the transfer and output characteristics of an α-graphyne ballistic nanoribbon FET. We used the tight-binding model with nearest-neighbor approximation to obtain the band structure which gives the same band structure as the one found from the DFT. In order to simulate the I-V characteristics of the transistor we used the non-equilibrium Green's function (NEGF) formalism. The results show that the modeled FET can provide a high Ion/Ioff ratio and low subthreshold swing. We also studied the effects of defects as defects cannot be avoided in any practical device. The study shows that the Ion/Ioff ratio and subthreshold swing improves as defects are added, but the delay time and dynamic power dissipation worsen.

Comparison of the safety and efficacy of single injection of subtenon triamcinolone and topical dexamethasone in reducing postoperative inflammation after phacoemulsification and intraocular lens implantation.

OBJECTIVE: To compare the safety and efficacy of single injection of sub-tenon triamcinolone and topical dexamethasone in reducing post-operative inflammation after phacoemulsification and intraocular lens implantation. METHODS: The randomised controlled study was conducted at Khyber Teaching Hospital, Peshawar, Pakistan, from September 2013 to February 2014. Patients who had undergone uneventful phacoemulsification with intraocular lens implantation by the same surgeon were included. Patients in Group A received 0.1% dexamethasone eye drops and those in Group B received sub-tenon triamcinolone injection (40mg/1ml). Follow-up was at 1st day, 14th day and 6 weeks post-operatively. At follow-up visit, grades of anterior chamber cells and aqueous flare were examined with slit lamp, and intraocular pressure was recorded. RESULTS: Of the 108 patients, each group had 54(50%) subjects. The mean age was 58.87±9.69 years (range: 33 to 84 years) in Group A and 57.77±8.93 years (range: 30 to 78 years) in Group B (p=0.544). On the first post-operative day, all the patients in both groups had some degree of inflammation in the anterior chamber. On the 14th post-operative day, anterior chamber cells were present in 4(7.4%) eyes in Group A and in 3(5.55%) eyes in Group B (p>0.999), while aqueous flare was present in 5(9.25%) eyes in Group A and 9(16.66%) eyes in Group B (p=0.391). Six weeks after the operation, no anterior chamber cells or aqueous flare was seen in any eye in either group. CONCLUSIONS: Sub-tenon triamcinolone injection was found to be a safe and effective alternative to topical dexamethasone for control of post-operative inflammation after phacoemulsification.

The effect of substrate, season, and agroecological zone on mycoflora and aflatoxin contamination of poultry feed from Khyber Pakhtunkhwa, Pakistan.

To study the effects of and interactions among feed types, seasons, and agroecological zones on the total fungal viable count and aflatoxins B1 (AFB1), B2 (AFB2), G1 (AFG1), and G2 (AFG2) production in poultry feed, an experiment was conducted using three-factorial design. A total of 216 samples of poultry feed ingredients, viz. maize, wheat, rice, cotton seed meal (CSM), and finished products, that is, starter and finisher broilers' rations, were collected from Peshawar, Swat, and D. I. Khan districts of Khyber Pakhtunkhwa, Pakistan, during the winter, spring, summer, and autumn seasons of the year 2007/2008. Analysis of variance showed that there was a complex interaction among all these factors and that this influenced the total fungal viable count and relative concentrations of the aflatoxins produced. Minimum total culturable fungi (6.43 × 10³ CFUs/g) were counted in CSM from D. I. Khan region in winter season while maximum (26.68 × 10³ CFUs/g) in starter ration from Peshawar region in summer. Maximum concentrations of AFB1 (191.65 ng/g), AFB2 (86.85 ng/g), and AFG2 (89.90 ng/g) were examined during the summer season whereas the concentration of AFG1 was maximum (167.82 ng/g) in autumn in finisher ration from Peshawar region. Minimum aflatoxins were produced in the winter season across all the three agroecological zones.

Antitussive and toxicological evaluation of Vitex negundo.

Vitex negundo Linn. (Verbenaceae) is used in traditional medical system for respiratory disorders. This study was carried out to investigate its cough-relieving potential. The antitussive effect of the butanolic extract of V. negundo (Vn) on sulphur dioxide (SO(2))-induced cough was examined in mice. Safety profile of Vn was carried out by observing acute neurotoxicity, median lethal dose (LD(50)) and behavioural signs. Vn dose-dependently (250-1000 mg kg(-1)) inhibited the cough provoked by SO(2) gas in mice and exhibited maximum protection after 60 min of administration. At 1000 mg kg(-1), Vn caused maximum cough-suppressive effects i.e. cough inhibition at 60 min was 67.4%, as compared to codeine (10 mg kg(-1)), dextromethorphan (10 mg kg(-1)) and saline having cough-inhibitory potential 75.7%, 74.7% and 0%, respectively. LD(50) value of V. negundo was found to be greater than 5000 mg kg(-1). In toxicity tests, no signs of neural impairment and acute behavioural toxicity were observed at antitussive doses and extract has been well tolerated at higher doses. These results indicate that V. negundo exhibits antitussive effect and it was found devoid of toxicity.

Echocardiographic profile of rheumatic heart disease at a tertiary cardiac centre.

BACKGROUND: Rheumatic Heart Disease (RHD) continues to be a major public health problem in developing countries like Pakistan. Objective of this cross sectional-analytical study was to analyze the severity of valvular lesions on echocardiography in patients pre-diagnosed with RHD. METHODS: The transthoracic echocardiographic records of RHD patients from 2004 to 2008 were retrospectively reviewed for type and degree of valvular involvement according to AHA/ACC guidelines. RESULTS: A total of 13,414 patients [7,219 Males (53.8%), 6,195 Females (46.2%)] ranging from 11 to 90 years with a mean age of 42.33 +/- 18.976 were studied. On echocardiography, 7,500 (56%) had mitral regurgitation (8.8% severe MR), 6,449 (48.2%) had tricuspid regurgitation (7.1% severe TR) and 5,550 (41.4%) had aortic regurgitation (4.8% severe AR). MS was detected in 2,729 (20.3%) patients (15.3% severe MS), AS in 102 (0.8%) and TS in 31 (0.2%) patients. Mixed mitral valve disease was seen in 3,185 (23.7%), mixed aortic valve disease in 222 (1.7%) and mixed tricuspid valve disease in 47 (0.4%) patients. All three valves were involved in 2,826 (21.06%) patients, combination of mitral and aortic valves in 3,103 (23.13%), mitral and tricuspid in 3,784 (28.2%), and mitral only in 3,701 (27.59%) patients. There was some mitral valve abnormality in all patients. CONCLUSION: Mitral valve was most commonly affected, while regurgitant lesions were more common than stenotic lesions, and most severe in younger patients. All valvular lesions had almost an equal distribution among the sexes, except aortic regurgitation, which was more common in females. Therefore, echocardiography should be done routinely for patients with RHD, focusing on younger population, to facilitate diagnosis and definitive treatment before complications set in.

Relative frequency of hepatitis B and C viruses in patients with hepatic cirrhosis at DHQ Teaching Hospital D. I. Khan.

BACKGROUND: Hepatic cirrhosis is an important cause of morbidity and mortality worldwide. It is generally considered irreversible and premalignant condition. However reversibility of the disease has been demonstrated in some cases after removal of the cause. There are various causes leading to cirrhosis but viral cause is the most common cause worldwide. In developing countries its prevalence is more where poor knowledge about viral infections is the main cause of spread. Mode of spread and sequel of Hepatitis B Virus (HBV) and Hepatitis C Virus (HCV) are almost similar. The present study was designed to know the relative frequency of both viruses in patients with cirrhosis. METHOD: This study was conducted in the Medical unit of District Teaching Hospital of Dera Ismail Khan, from the first of May to 30th November 2002. Cirrhotic patients were admitted to Medical ward and necessary investigations were done on blood specimen for HBV and HCV. Immunoassay chromatographic technique one-step device (ACON Laboratories, USA) was applied for its viral screening. At the end 60 cirrhotic patients were analyzed for findings and comparison with other studies. RESULTS: Out of 60 patients, 28 (46.67%) were found infected with HBV, 8(13.33%) with HCV, 24 (40%) with no markers of either two viruses. One case (0.16%) was found positive for both viruses. CONCLUSION: Cirrhosis liver due to HBV is more common than HCV in this region. Males are affected more than females.

Impact of class attendance upon examination results of students in basic medical sciences.

BACKGROUND: A number of studies have shown the impact of attending the classes during the session on examination results of students. Students with good lecture attendance show good results while those with poor lecture attendance are at risk for poor performance in the examinations. In this study we wanted to test this in students of basic medical sciences in our set up. METHODS: All the students in Basic Medical Sciences of Gomal Medical College, D.I. Khan, Pakistan, during the session 1999-2000 were enrolled for this study. Performance of these students in one of their three annual term tests, which covered duration of studies for four months, from February 2000 to May 2000, was analyzed. Students were grouped into two, Group-A with > or = 75% attendance and Group-B with < 75% attendance. The frequency of failure in the two groups was compared using the chi square test. RESULTS: Results of the term test showed that the percentage of failure in students of Group-B with less than 75%, attendance was significantly higher when compared to Group-A with equal or more than 75% attendance. CONCLUSION: Our results supported the previous studies showing that attendance in the classes during teaching sessions had a direct impact on performance of students in the examinations. Students with good attendance show good results while those with poor attendance are at risk for poor performance during examinations in basic medical sciences.