Microstructure and Mechanical Properties of Aluminum Cast Alloy A356 reinforced with Dual-Size B4C Particles

The paper details the studies carried out on a dual-size particulate composite prepared by stir casting using A 356 aluminum alloy and B4C powders. Three composite compositions, viz., A356 plus 2% B4C (44µm size and 105µm size in 1:1 ratio), 4% B4C (3:1 ratio), and 6% B4C (1:3 ratio) were cast in finger molds, from which test specimens were prepared for hardness and tensile tests as well as for metallography. Vickers hardness tests, tensile tests and microstructure analysis using an optical microscope were conducted. The results obtained indicated that the B4C particles were evenly distributed in the alloy matrix. EDS also revealed the presence of B4C in all the three composites.  In general, the hardness and tensile strengths increased with increase in concentration B4C powders. While the increase in hardness was increases less than 15%, there was significant increase (more than 35 %) in tensile strength. However, the ductility represented by % elongation, which was already very low in A 356 cast alloy (24.2%,), further decreased in composites. Tensile fractography results shows inter crystalline fracture where the breakage in the B4C particle instead of deboning were observed

Hyperbolic discounting in analyzing investment in groundwater irrigation in India

Researchers are often confronted with the choice of discount rate as well as the method of discounting for estimating the amortized cost of long-term investment in agriculture including groundwater irrigation. The obvious choice is to use the opportunity cost of capital, which is the prevailing interest rate of around 9 percent (compounded – exponential basis), charged on longterm agriculture loans. However, using the ‘exponential’ basis does not provide a realistic amortized cost of irrigation as it over estimates the value of investment due to ‘exponential’ basis as demonstrated above. In order to obtain an empirical estimate of this interest rate, using field data from farmers three dry agro-climatic zones of Karnataka (Shamsundar (1996), Sripadmini (2001), Chaitra (2002), Rajendra (2003)) nominal investment per irrigation well is considered (Table 3). The nominal investments were deflated using the index number of wholesale prices (1993-94 base year). Considering nominal and real growth in investment per irrigation well between the 1980’s and 2000’s in the three agro-climatic zones of Karnataka, using the exponential discounting, the nominal investment per well is found to be increasing between 3.7 and 5.7 percent. This shows that the amortization of groundwater investment cannot exceed say six percent. The real (exponential rate of) interest is computed by deflating the initial year investment and the terminal year investment per irrigation well using the 1993-94 as base all India wholesale price index numbers. It is found that in real terms the investment per well is falling between –2.5 percent and –0.17 percent.(Table 3). The fall in real investment is due to increased competition by rig owners in offering almost uniform rate of drilling over the years in several aquifers of Karnataka. For instance the price of drilling has been between Rs. 35 and Rs. 50 per feet between 1985 and 2005 for shallow bore wells. The phenomenon may not be very different in other states of peninsular India. A comparison of nominal investment in terminal year and the estimated cost of well in 2005 indicates that in EASTREN DRY ZONE the nominal interest rate is 3.7 percent, the real interest rate is –0.17 percent and the investment per well in 2002 (terminal year) being Rs. 53,478 and in 2005 (current year) being Rs. 59578 are comparable. But in CENTRAL DRY ZONE, while the nominal investment per well in 2000 is Rs. 45,000, the estimated investment in 2005 is Rs. 59,193, which is an unrealistically high exponential growth obtained by compounding the initial investment of Rs. 18,480 from 1984 to 2005. Similarly in EASTREN DRY ZONE, while the actual investment per well in 2000 is Rs. 75,095, the estimated investment per well in 2005 works to Rs. 97,702, which is again unrealistic. As the real interest rate is negative in irrigation wells, this could be one of the reasons for mushrooming of irrigation wells in Karnataka, since this makes investment affordable across different classes of farmers. Thus this analysis has two messages. One, that the nominal interest rate which has to be considered for amortizing investment on irrigation well can be around 3 to 6 percent, and that the real investment per well is falling.hyperbolic discounting, groundwater, exponential, Environmental Economics and Policy, Institutional and Behavioral Economics, Research Methods/ Statistical Methods, D9, Q25, M4,

Simple High-performance Liquid Chromatographic Method for the Determination of Acyclovir in Pharmaceuticals

An assay method for the determination of acyclovir from pharmaceutical preparations has been developed for assessment of product quality utilising high-performance liquid chromatography. The chromatographic conditions comprised a reversed-phase C18 column (250×4.6 mm i.d.) with a mobile phase of acetonitrile-20 mmol l−1 aqueous ammonium acetate buffer of pH 4.5 (40:60). The flow rate was 0.8 ml min−1 and UV detection was used at 250 nm. Calibration graph was linear in the range 1.98–59.4 μg ml−1. The method has been validated according to current guidelines including assay of pharmacopoeial standard tablets. Recoveries ranged from 96.64 to 99.53%. The exipients present in the tablets did not interfere with the method

Silent meningioma: a cause of quadriperesis in total knee arthroplasty

Total knee arthroplasty (TKA) is a treatment for end stage osteoarthritis.  Majority of them in the older age group with associated co-morbidities and increased the risk for stroke. Asymptomatic meningiomas may become symptomatic and presents with variable symptoms depending on the size and location of the tumour. We report a case of a 58 years old lady who underwent bilateral TKA under combined spinal epidural anaesthesia with an uneventful post-operative course with post-operative analgesia. Patient developed dysphasia and weakness in upper and lower limbs. Following computed tomography of the brain revealed a meningioma in the falx region. Patient treated with steroid and underwent elective surgery for meningioma without any complications. Asymptomatic brain tumours can become symptomatic after surgery and urgent initiation of neurologic evaluation and strong recommendation to initiate intracranial pressure management oriented therapy in time.

Effect of Office Bleaching Agents on the Shear Bond Strength of Metallic Brackets Bonded Using Self-Etching Primer System at Different Time Intervals – An In-Vitro Study

A common method of treating discoloured teeth is to bleach them using hydrogen peroxide. Many studies in the literature have concluded that bleaching reduces shear bond  strength of composite resin significantly and thus, to achieve clinically adequate shear bond strength of composite for bonding brackets to bleached enamel, it is important to find out the various methods of reducing adverse effects of bleaching. It has been proposed by some authors that a delay in bonding effectively reverses the effects of  bleaching on bond strength. OBJECTIVES- To test the null hypothesis that there is no statistical significance in (1) bond strength and (2) failure site location with bleached and unbleached enamel prepared with TransbondPlus Self-etching Primer between  different time intervals. MATERIALS AND METHODS- Sixty freshly extracted human premolar teeth were randomly divided divided into three groups of 20 teeth each Bleaching treatment was performed at two different time intervals (bleaching immediately before bonding and bleaching 30 days before bonding). All brackets were bonded with a self-etching primer system. The shear bond strength of these brackets was measured and recorded in MPa. Adhesive remnant index (ARI) scores were determined after the brackets failed. RESULTS- The mean shear bond strength of Group A (control) is found to be 20.4315 MPa (SD± 6.81041) which was reduced to 11.1955 MPa (SD ± 4.58041) when bonding was done immediately after bleaching (group B). The shear bond strength increased to 14.9910 MPa (SD ± 4.74545) when enamel was 14.9910 MPa (SD ± 4.74545) when enamel was Group C) Pair wise comparison of shear bond strength between the three groups  using Post hoc Tukey test showed that there is a very high statistically significant difference between shear bond strength of all three groups. CONCLUSION This study shows that bonding immediately after bleaching significantly reduces the shear bond strength , it can be reversed by a delay in the bonding by 30 days which shear bond strength , it can be reversed by a delay in the bonding by 30 days which improves the shear bond strength as reflected  in the results of the study ,So it is advisable to delay the orthodontic bonding procedure by an interval of 30 days to improve survival rates and prevent frequent breakages of brackets due to bond failure

On Water Quality Aspects of Manchanabele Reservoir Catchment and Command Area (karnataka)

Reservoirs and lakes occupy a prominent place in the history of irrigation in South India. Tanks are considered to be useful life saving mechanism in the water scarcity areas which are categorized as Arid and Semi-arid zones. The lakes and reservoirs, all over the country without exception, are in varying degrees of environmental degradation. The degradation is due to encroachments, eutrophication (due to the inflow of domestic and industrial effluents) and siltation. There has been a quantum jump in population during the last century without corresponding expansion of civic facilities resulting in deterioration of lakes and reservoirs, especially in urban and semi urban areas becoming sinks for the contaminants. The degradation of reservoir and lake catchments due to deforestation, stone quarrying, sand mining, extensive agricultural use, consequent erosion and increased silt flows have vitiated the quality of water stored in reservoirs and lakes. Infrastructure development, housing projects, and inflow of untreated wastewater into the water bodies have resulted in deterioration of urban and rural lakes and reservoirs. The paper discusses the physico-chemical and bacteriological studies carried out on surface and ground water in the reservoir catchment and the command areas .The results of analyses of water samples reveal that water is polluted at certain locations. The presence of total –Coliform and Faecal-Coliform in ground water and reservoir and lake water at certain locations indicates that water is polluted with waste water. The nitrate level varies between 0.6ppm to 135.8ppm, and exceeds the drinking water standards at 10 locations in the catchment and command area. The suitability of water for irrigation is evaluated based on SAR, %Na, RSC and Salinity hazards. Most of the samples fall in the suitable range for irrigation purpose. The inflow of urban runoff into the surface water bodies has resulted in pollution of reservoir and ground water at certain locations. The paper also discusses the measures proposed to reduce pollution levels in the reservoir, its catchment and command area

Symmetries and noise in quantum walk

We study some discrete symmetries of unbiased (Hadamard) and biased quantum walk on a line, which are shown to hold even when the quantum walker is subjected to environmental effects. The noise models considered in order to account for these effects are the phase flip, bit flip and generalized amplitude damping channels. The numerical solutions are obtained by evolving the density matrix, but the persistence of the symmetries in the presence of noise is proved using the quantum trajectories approach. We also briefly extend these studies to quantum walk on a cycle. These investigations can be relevant to the implementation of quantum walks in various known physical systems. We discuss the implementation in the case of NMR quantum information processor and ultra cold atoms.Comment: 19 pages, 24 figures : V3 - Revised version to appear in Phys. Rev. A. - new section on quantum walk in a cycle include

A single case study on Varicocele

A varicocele is a dilatation and tortuosity of Pampiniform venous plexus within the spermatic cord. The condition is important etiological factor in male infertility. References are not available in Ayurvedic classics about particular disease which resembles the clinical picture of varicocele. Varicocele can be correlated to Sirajagranthi of Vrushanakosa. This helps to draw some conclusions regarding the treatment plan-up for varicocele. Jalaukavacharana is very much effective in Sirajagranthi. Hence Jalaukavacharana is tried in varicocele which can be correlated to Sirajagranthi of Vrishanakosha. It is safe and affordable. In present study total 4 sittings of Jalaukacharana was done. Marked reduction in the symptoms like pain and swelling was observed after second sitting. Jalaukacharana is very much effective in management of varicocele

To evaluate the effect of Arka Pratisaraneeya Kshara in the management of Kadara w.s.r. to Corn

Kadara is a Kshudraroga which is characterized by hard thickened type swelling, largely confined to the Pada but also seen in Hastha. The disease Kadara is not a life threatening condition, but makes the life of the sufferer miserable. Aetiological factors include injury due to the thorn prick, stone, cut, friction, pressure or wearing ill-fitting and tight shoes. The disease Kadara described in Ayurveda and Corn in western medical textbooks have absolute similarity in their manifestation. The management of corn is done by application of salicylic acid, corn caps, and invasive procedures like cryotherapy, laser, chemical cauterization, electric cauterization and surgical excision. But the results by these procedures are not satisfactory and there are more chance of recurrence. Kshara is indicated in management of Kadara. Kshara Karma is unique procedure used since ancient time which best among Shastra and Anushastra due to its comprehensive multi-faceted effects. Hence the present study was undertaken for evaluation of efficacy of Arkapratisaraneeya Kshara obtained was compared with the results of Agnikarma using Panchalohashalaka which is a standard and established study