P-N Junction Oxide Nanoparticle as a Novel Photocatalyst for Solar Applications

Due to the spectral limitation of popular photocatalysts (PC) TiO2 and ZnO, there is quest for modification of the existing PC to enhance their photocatalytic performance. It has been demonstrated that the coupled nanostructured semiconductors in the form of nanocomposites (NC) enhance the performance by the mutual charge transfer of carriers between each semiconductor components with compatible chemical and electrical properties. ZnO (Bg: 3.37 eV) n-type semiconductor, is most important PC because of its high photosensitivity and stability. CuO (Bg: 1.85 eV), a p-type semiconductor, can be used in conjunction with ZnO to further improve its photocatalytic activity (PCA). Herein, a p-n junction oxide photocatalyst was synthesized by using a simple ball milling technique. The structural, optical and surface properties of the p-n junction photocatalyst CuO/ZnO were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), UV-Vis spectroscopy, Zetasizer Nano ZS (Malvern). The PCA of the photocatalyst was evaluated by photocatalytic oxidation of Methylene Blue (MB). Our study demonstrates a novel p-n junction oxide photocatalyst CuO (wt. 10%)/ZnO having superior PCA for the degradation of model dye under the illumination of UV-Vis light. The MB solution was degraded by 100% within 15 min by the use of CuO (wt. 10%)/ZnO photocatalyst. The enhanced PCA is anticipated from many micro p-n junction formed between ZnO-CuO upon ball milling, which helps in efficient electron/hole pair charge separation upon excitation

Direct Nitrous Oxide Emissions From Tropical And Sub-Tropical Agricultural Systems : A Review and Modelling of Emission Factors

We acknowledge the financial support from the CGIAR Research Programs on Climate Change, Agriculture and Food Security (CCAFS). Grant ref. n. P25.Peer reviewedPublisher PD

Laparoscopic Cholecystectomy in Chronic Calculus Cholecystitis

Introduction: Laparoscopic cholecystectomy has clearly become the choice over open cholecystectomy in the treatment of hepatobiliary disease since its introduction by Mouret in 1987. This study evaluates a series of patients with chronic calculus cholecystitis who were treated with laparoscopic and open cholecystectomy and assesses the outcomes of both techniques. Objective: To evaluate the efficacy of laparoscopic vs open cholecystectomy in chronic calculus cholecystitis and establish the out-comes of this treatment modality at Lumbini Medical College and Teaching Hospital. Methods: This was a retrospective analysis over a one-year period (January 1, 2012 to December 31, 2012), per-formed by single surgeon at Lumbini Medical College and Teaching Hospital located midwest of Nepal. 166 patients underwent surgical treatment for chronic calculus cholecystitis. Patients included were only chronic calculus cholecystitis proven histopathologocally and the rest were excluded. Data was collected which included patients demographics, medical history, presentation, complications, conversion rates from laparoscopic. cholecystectomy to open cholecystectomy, operative and postoperative time. Results: Patients treated with laparoscopic cholecystectomy for chronic calculus cholecystitis had shorter operating times and length of stay compared to patients treated with open cholecystectomy for chronic calculus cholecystitis. Conversion rates were 3.54% in chronic calculus cholecystitis during the study period. Complications were also lower in patients who underwent laparoscopic cholecystectomy versus open cholecystectomy for cholelithiasis. Conclusions: Laparoscopic cholecystectomy appears to be a reliable, safe, and cost-effective treatment modality for chronic calculus cholecystitis

Factors Affecting the Productivity of Coffee in Gulmi and Arghakhanchi Districts of Nepal

Coffee is one of the major potential cash crops with lucrative export value grown in mid-hills of Nepal. Nepalese coffee production has suffered long by low productivity. Research was conducted from February to May, 2019 to analyze the factors affecting the productivity of coffee in Arghakhanchi and Gulmi districts of Nepal. These two districts were, purposively selected for this study taking account of comparative advantage and past studies recommendations for coffee sector. Altogether, 100 coffee growing households 50 from each, Arghakhanchi and Gulmi, were sampled by using multistage sampling technique. A pre-tested semi-structured interview schedule was used to collect the primary information while secondary information was collected reviewing the relevant publications. Ordinary Least Square (OLS) regression model was used to determine the factors affecting the productivity of coffee. The study revealed that the number of active family members involved in coffee production (0.000), adoption of income diversification through intercropping (0.005), training (0.072) and technical assistance (0.021) had positive and significant effect on coffee productivity. Encouraging the household to have coffee production as their primary occupation, providing technical assistance on rational land utilization and intercropping and strengthening the skill and knowledge of farmers through trainings could significantly support in increasing the productivity of coffee

Initial Experience of Percutaneous Nephrolithotomy at Lumbini Medical College

  Introduction: Renal stone disease is a challenging problem in urologic practice especially in our locality because of large stone burden and recurrence. Since ,the early 1980s when percutaneous nephrolithotomy (PCNL) was established for management of renal stones, open surgical procedures have virtually been replaced. PCNL is a safe, effective and minimally invasive approach compared to open surgery for patients with large single, multiple or staghorn stones. The aim of this prospective study was to evaluate and to review our experience with PCNL in management of renal and upper ureteric stones.   Methods: Prospective study carried out at Lumbini Medical College and Teaching Hospital during 1stJanuary 2011 to 31st October 2011. Sixty patients were evaluated and subjected to PCNL. After clinical investigations like ultrasonography (USG) and intravenous urography (IVU), once patients were found to have renal or upper ureteric stones they were informed and explained about PCNL, its likely complications, probable hospital stay, the cost of treatment and data were recorded along with the operative time, estimated blood loss, stone burden, stone-free rate, length of hospitalization and complications .Patients were followed up after three months to rule out recurrence of stones by plain abdominal x-ray of kidney, ureter and bladder and USG.   Results: Out of 60 patients 35 were male and 25 were female (M: F=1.4:1) with mean age of 37 years and were subjected to PCNL monotherapy. With the average stone size of 3.26cm, the mean operative time was 78 minutes. Complete stone removal achieved by PCNL alone in 60 cases, with insignificant residual small stones we achieved 97% stone clearance rate. The mean hospital stay was 3.7 days. No Serious complications were encountered, 9 (15%) patients required blood transfusion and 3 (5%) patients developed transient post-operative pyrexia.   Conclusion: PCNL is the first line treatment option for management of large renal stones which as monotherapy has advantages in removal of renal and upper ureteric stones and achieving excellent results with minimal morbidity

Thermal structure and exhumation history of the Lesser Himalaya in central Nepal

The Lesser Himalaya (LH) consists of metasedimentary rocks that have been scrapped off from the underthrusting Indian crust and accreted to the mountain range over the last ~20 Myr. It now forms a significant fraction of the Himalayan collisional orogen. We document the kinematics and thermal metamorphism associated with the deformation and exhumation of the LH, combining thermometric and thermochronological methods with structural geology. Peak metamorphic temperatures estimated from Raman spectroscopy of carbonaceous material decrease gradually from 520°–550°C below the Main Central Thrust zone down to less than 330°C. These temperatures describe structurally a 20°–50°C/km inverted apparent gradient. The Ar muscovite ages from LH samples and from the overlying crystalline thrust sheets all indicate the same regular trend; i.e., an increase from about 3–4 Ma near the front of the high range to about 20 Ma near the leading edge of the thrust sheets, about 80 km to the south. This suggests that the LH has been exhumed jointly with the overlying nappes as a result of overthrusting by about 5 mm/yr. For a convergence rate of about 20 mm/yr, this implies underthrusting of the Indian basement below the Himalaya by about 15 mm/yr. The structure, metamorphic grade and exhumation history of the LH supports the view that, since the mid-Miocene, the Himalayan orogen has essentially grown by underplating, rather than by frontal accretion. This process has resulted from duplexing at a depth close to the brittle-ductile transition zone, by southward migration of a midcrustal ramp along the Main Himalayan Thrust fault, and is estimated to have resulted in a net flux of up to 150 m^2/yr of LH rocks into the Himalayan orogenic wedge. The steep inverse thermal gradient across the LH is interpreted to have resulted from a combination of underplating and post metamorphic shearing of the underplated units

The Scenario of Carbonaceous Aerosols and Total Solar Radiation in Two Cities in Nepal

Measurement of elemental carbon (EC) and black carbon (BC) aerosols was carried out using AE-31, 7 channel aethalometer at Kathmandu and Biratnagar; two mega cities of Nepal, for five months, January to May 2011 to study its temporal and spatial variation. Total solar radiation was also monitored using Kipp and Zonen CMP 6 pyranometer. Monthly concentration variation for EC and BC was distinct in both study sites. At Biratnagar, monthly EC concentration varies from 3.3 -20.7 µg /m3 while in Kathmandu it varies between 6.0-13.7 µg /m3. Similarly, BC monthly concentration ranges from 3.3 -20.1 µg /m3 and 7.0-14.9 µg /m3 respectively. It was found that both EC and BC were highest during January in both the sites and it decreases gradually. Monthly average solar radiation shows a maximum value in May and minimum in January. A distinct anti-correlation between monthly average carbonaceous aerosols and total solar radiation was observed. Moreover, there was a pronounced diurnal variation of both carbonaceous aerosols EC and BC in the sites with two high peaks one in the morning at about 9:00 and another at late evening 20:00 local time with minimum concentration in the afternoon. The nature of peaks were different at two sites. Biratnagar shows a larger evening peak while Kathmandu shows in the morning inferring heavy domestic and industrial fuel consuming activities in evening and morning respectively. In addition to this, daily and monthly concentration of EC was more than BC at Biratnagar reflecting slightly more biomass fuel consumption than fossil fuel for domestic, industrial and other urban activities. In contrast to this, Kathmandu shows more domination of fossil fuel than biofuel because of reverse order concentration of carbonaceous aerosols. Total solar radiation also shows apparent diurnal variation in both sites with the highest value at around noon time

Effective One-Dimensional Coupling in the Highly-Frustrated Square-Lattice Itinerant Magnet CaCo2−y_{\mathrm{2}-y}As2_{2}

Inelastic neutron scattering measurements on the itinerant antiferromagnet (AFM) CaCo$_{\mathrm{2}-y}$As$_{2}$ at a temperature of 8 K reveal two orthogonal planes of scattering perpendicular to the Co square lattice in reciprocal space, demonstrating the presence of effective one-dimensional spin interactions. These results are shown to arise from near-perfect bond frustration within the $J_1$-$J_2$ Heisenberg model on a square lattice with ferromagnetic $J_1$, and hence indicate that the extensive previous experimental and theoretical study of the $J_1$-$J_2$ Heisenberg model on local-moment square spin lattices should be expanded to include itinerant spin systems

Long-term effect of tillage, nitrogen fertilization and cover crops on soil organic carbon and total nitrogen content

No-tillage, N fertilization and cover crops are known to play an important role in conserving or increasing SOC and STN but the effects of their interactions are less known. In order to evaluate the single and combined effects of these techniques on SOC and STN content under Mediterranean climate, a long term experiment started in 1993 on a loam soil (Typic Xerofluvent) in Central Italy. The experimental variants are: conventional tillage (CT) and no-tillage (NT), four N fertilization rates (N0, N1, N2 and N3) and four soil cover crop (CC) types (C - no cover crop; NL - non-legume CC; LNL - low nitrogen supply legume CC, and HNL - high nitrogen supply legume CC).The nitrogen fertilization rates (N0, N1, N2 and N3) were: 0, 100, 200, 300kgNha-1 for maize (Zea mays, L.); 0, 60, 120,180kgNa-1 for durum wheat (Triticum durum Desf.); 0, 50, 100, 150kgNha-1 for sunflower (Helianthus annuus L.).From 1993 to 2008, under the NT system the SOC and STN content in the top 30cm soil depth increased by 0.61 and 0.04Mgha-1year-1 respectively. In the same period, the SOC and STN content under the CT system decreased by a rate of 0.06 and 0.04Mgha-1year-1 respectively. During the experimental period, N1, N2 and N3 increased the SOC content in the 0-30cm soil layer at a rate of 0.14, 0.45 and 0.49Mgha-1year-1. Only the higher N fertilization levels (N2 and N3) increased STN content, at a rate of 0.03 and 0.05Mgha-1year-1.NL, LNL and HNL cover crops increased SOC content by 0.17, 0.41 and 0.43MgCha-1year-1 and -0.01, +0.01 and +0.02MgNha-1year-1.Significant interactions among treatments were evident only in the case of the N fertilization by tillage system interaction on SOC and STN concentration in the 0-10. cm soil depth in 2008.The observed SOC and STN variations were correlated to C returned to the soil as crop residues, aboveground cover crop biomass and weeds (C input).We conclude that, under our Mediterranean climate, it is easier to conserve or increase SOC and STN by adopting NT than CT. To reach this objective, the CT system requires higher N fertilization rates and introduction of highly productive cover crops