763 research outputs found
Direct bandgap materials based on the thin films of SexTe100 - x nanoparticles
In this study, we fabricated thin films of Se(x)Te(100 â x) (xâ=â0, 3, 6, 9, 12, and 24) nanoparticles using thermal evaporation technique. The results obtained by X-ray diffraction show that the as-synthesized nanoparticles have polycrystalline structure, but their crystallinity decreases by increasing the concentration of Se. They were found to have direct bandgap (E(g)), whose value increases by increasing the Se content. These results are completely different than those obtained in the films of Se(x)Te(100 â x) microstructure counterparts. Photoluminescence and Raman spectra for these films were also demonstrated. The remarkable results obtained in these nanoparticles specially their controlled direct bandgap might be useful for the development of optical disks and other semiconductor devices
Effect of seawater ageing on fracture toughness of stitched glass fiber/epoxy laminates for marine applications
Composite materials are used in various industries such as marine, aircraft, automotive, etc. In marine applications, composites are exposed to seawater, which can affect their mechanical properties due to moisture absorption. This work focuses on the durability of composite materials under the short-term effect of seawater ageing. The specimens were prepared from glass fiber/epoxy using a hand lap-up method and stitched in the z-direction with Kevlar fiber. The specimens were submerged in seawater for 24 and 35 days. A significant decrease in maximum load was found as specimen immersion time in seawater increased. The seawater ageing also affected fracture toughness with a reduction of 30% for 24 days immersion and 55% for 35 days. The ageing also caused the swelling of composites due to moisture absorption, which increased the weight of the specimens. Compared to the dry specimens, the weight of the specimen for 24 days increases to 5.2% and 7.89% for 35 daysâ seawater ageing. The analysis also showed that due to seawater ageing, the de-bonding rate increased as the number of days increased
Effect of Nitrogenous Fertilizer on the Vegetative Growth and Yield Attribute of Pea (Pisum sativum L.)
An experiment was conducted to study the effect of chemical fertilizer on the pea growth and yield attributes. Therefore, the main objective of this study was to investigate the effect of chemical fertilizer alone and in combination. This study consists of three different nitrogen levels (90, 100 and 110 kg ha-1as urea), three different levels of phosphorus (60, 70 and 80 P2O5 kg ha-1 as DAP) and their combination. Treatments were arranged in a complete randomized block design with three replications. The results showed that both the single and combined application of nitrogen and phosphorus fertilizer increased the growth and yield attribute of the pea plant. Maximum number of primary (6.91) and secondary branches per plant (7.97), number of leaves per plant (12.50) and plant height (51.24 cm) was attained by the combine application of P80+N110. Similarly, the maximum increase in yield parameters such as pod length (7.5 cm), number of pods per plant(7.23), pod weight (12.50 g) and number of grains per pod was obtained in P80+N110. In general, combined application of fertilizers significantly increased all the growth and yield attribute of the pea plant when compared to fertilizers applied alone with respect to control
Call census, habitat suitability modeling and local communitiesâ perceptions for the conservation of a globally threatened avian flagship species
The Western tragopan (Tragopan melanocephalus) is recorded in the IUCN Red List of 2017 as a Vulnerable bird species in Pakistan.  This study was conducted to investigate and resolve the conservation challenges surrounding the species in two major habitat zones - Salkhala Game Reserve and Machiara National Park. The study was arranged in May-June 2020 for the call count census. Local residentsâ perceptions and a habitat suitability map were developed for the species using MaxEnt model based on previously recorded occurrence points as well as recorded in the survey. A total of 26 western Tragopans were identified by call count during the sampling period. Results of modeling habitat suitability of the Western tragopan showed that the species suitable habitats are small and patchy in Pakistan. We found that the Normalized Difference Vegetation Index (NDVI) with 40.6 percent contribution was the most important variable in shaping the species distribution. Our model identified some new suitable patches which can be the target of future field monitoring for finding new populations of the species. This study provides valuable information for conservation of Western tragopan a globally threatened avian flagship species in Pakistan
Performance Evaluation of UK Acquiring Companies in the Pre and Post-Acquisitions Periods
This paper has two objectives: first, it examines the financial performance of twenty UK based acquiring companies over the period of five years (2009-2013) using financial ratios of Liquidity, Profitability and Solvency in order to empirically determine whether there is any significant financial performance changes in the operation of the underlying companies as a result of acquisitions. Both average ratio and paired t-test analysis have been conducted. The analysis concludes that none of the ratios proved statistical significance which shows that the underlying acquisitions did not influence changes in the financial performance of the acquiring companies. The paper also examines whether shareholders make short-term gain while opting for acquisitions by analyzing stocks return over 58 days window period i.e. 29 days prior to acquisition announcement and 29 days after acquisition announcement by applying CAPM model and AAR and CAAR analysis. The analysis concludes that none of the results show statistical significance which further asserts that UK shareholders do not make gain in the short-term as a result of the acquisition activities they have undertaken
Mathematical Logic Establishment for Automated Trash Controlling in Carding Machine
In this paper, it is intended to establish a mathematical logic for the purpose of removal of trash in an automatic way and removal of trash will refer to the cleaning process of carding machine. But the selection of degree of cleaning has to be optimum considering other process factors like fiber loss, fiber rupturing, neps generation etc. Higher degree of cleaning causes higher degree of fiber loss. And in spinning mill, fiber loss means money loss as raw cotton purchasing cost consumes 50% to 60% of total manufacturing cost of yarn in terms of Bangladesh. Alongside, fiber loss is affected the cleaning system because the system is designed for fiber cleaning, not for fiber loss. So, it is necessary to measure the performance of the system. For this purpose, we have chosen two terms, âCleaning Efficiency (C.E.)â to measure the degree of cleaning & âEffective Cleaning (E.C.)â to measure the performance of the system. In this paper, it is intended to describe a relationship between these two terms, graphical expression of the individuals, a way to calculate the force applied by mechanical means and the force required to clean. The ultimate result of this project is to find the relationship between the surface speed of taker-in and the trash weight of output material
The Influence of Plastic Mulching Materials and Sowing Dates on the Yield and Yield Components of Pea (Pisum sativum L.)
The use of plastic mulches affects the microclimate in the vicinity of the plant by modifying the radiation on the soil surface and reduce the loss of water. Pea is more nutritious and 2nd food source after cereals at Pakistan, but due to lake of proper management, yield is still not up to mark as compare to developed world. To reduce this problem, a field experiment was conducted to investigate the effect of mulching material and sowing dates on the yield of Pea. The study consisted of three different mulching materials (Polythene Black, Polythene Blue and Polythene Brown) with three different sowing dates (1st, 15th and 30th October) arranged in a Randomized Complete Block Design with three replications. The results showed that different sowing dates and mulching materials had significant effect on the yield parameters of Pea. Regarding sowing dates, maximum days to pod formation (8.08 days), pods plant?1 (21.25), Pod weight (18.84 g) and pod yield (4.39 tons ha?1) were noted in pea sown on October 1st. Whereas, minimum data of days to pod formation (3.08 days), pod plant?1 (15.34), pod weight (13.17 g) and pod yields (2.69tons ha?1) were recorded in pea sown on October 30th. In case of mulching types maximum number of pods plant?1 (19.00), pod length (6.89 cm), seeds pod?1 (7.78), pod weight (17.34 g) and pod yield (3.69 tons ha?1) were observed in pea mulched with Polythene Black, while minimum pods plant-1, pod length, seeds pod-1, pod weight and pod yield were found in control. The study suggested that pea should be sown on October 1st while mulched with Polythene Black to produce maximum yield and production in agro environment of district Peshawar
Pattern of Angulations and Common Indications for Extraction of Impacted Mandibular Third Molar at KMU-Institute of Dental Sciences, Kohat
Background: The extraction of an impacted mandibular third molar (MTM), with associated pathologies or clinical manifestations is an important and one of the most frequent decisions in dentistry. The angle formed by the longitudinal axis of second and third molar is used to determine angulation of impacted MTM. The aim of this study was to identify the pattern of angulations of impacted mandibular third molar and common indications for extraction associated with these angulations.Material and Methods: This descriptive cross-sectional study was carried out at Department of Oral & Maxillofacial Surgery, Khyber Medical University Institute of Dental Sciences, Kohat, Khyber Pakhtunkhwa (KP) from November 2017 to July 2018. A total of 349 patients presenting with impacted mandibular third molars were included in this study. Name, age, gender, address, the angulation of the impacted tooth and the indication for extraction of the impacted tooth were recorded. Data comprising of qualitative and quantitative variables were analyzed using SPSS version 17.Results: Out of 349 patients, 206 were male and 143 females, with the male to female ratio of 1.4:1. The age range of the patients was from 18 years to 60 years with a mean age of 26 ± 6 years. The most common age group with impacted third molar was †25 years followed by 26 to 30 yearsâ age group. The most common angulation was mesioangular followed by vertical, horizontal and distoangular impacted mandibular third molar. Pericoronitis was the most common indication for extraction in all angulations except horizontal impaction where root resorption of the second molar was more common.Conclusion: Mesioangular is the most common angulation in impacted mandibular third molars. Pericoronitis is the main indication for all angulations of impacted mandibular third molars except horizontal angulation, occurring mostly in the third decade of life
Analysis of microstructure and mechanical properties of bismuth-doped SAC305 lead-free solder alloy at high temperature
SAC305 lead-free solder alloy is widely used in the electronic industry. However, the problems associated with the growth formation of intermetallic compounds need further research, especially at high temperatures. This study investigates the doping of Bismuth into SAC305 in the various compositions of 1, 2, and 3 wt.%. The microstructure in terms of intermetallic compound particles and mechanical properties was examined after thermal aging at temperatures of 100 °C and 200 °C for 60 h. The microstructure examination was observed using scanning electron microscopy, and the chemical composition of each alloy was confirmed with an energy dispersive X-ray. Tensile tests were performed to find the mechanical properties such as yield strength and ultimate tensile strength. The intermetallic compoundâs phase analysis was identified using X-ray diffraction, and differential scanning calorimetry was done to study the temperature curves for melting points. Results showed that the addition of Bismuth refined the microstructure by suppressing the growth of intermetallic compounds, which subsequently improved the mechanical properties. The thermal aging made the microstructure coarsen and degraded the mechanical properties. However, the most improved performance was observed with a Bismuth addition of 3 wt.% into SAC305. Furthermore, a decrease in the melting temperature was observed, especially at Bismuth compositions of 3 wt.%
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