Application of the boundary element method to coupled fluid-structure interaction problems

The direct boundary element method (BEM) is used to formulate and numerically simulate the interaction of acoustic waves with submerged elastic structures and subsequently specialized to model finite beam transmission through locally curved elastic surfaces. These are structural-acoustic or fluid-solid interaction problems coupling scalar (acoustic) and vector (elastic) media. The problem is formulated in the frequency domain and modelled in three dimensions, and the elasto-acoustic phenomenon described by the acoustic and elastodynamic boundary integral equations (BIE) with pressure and displacement serving as the primarily variables;The general problem deals with a closed solid domain surrounded by an unbounded fluid medium so that with the well known radiation condition, the integral formulation requires modelling only the fluid-solid interface. This formulation is valid for both the exterior scattering/radiation behavior and the field transmitted into the elastic domain. A FORTRAN program (FS3D) was developed and implements the BEM approach using point collocation and isoparametric quadratic shape functions and provides pressure and displacements on the surface of the structure. The code includes separate acoustic and elastic post-processors to generate the far-field fluid pressure and the transmitted interior elastic displacements. Incident wave or the acoustic source is arbitrary but is normally taken to be either a plane or spherical wave or a bounded beam of any given form. The accuracy of the BEM approach is tested for simple shapes like spheres, spheroids and cylinders. Examples illustrate the structural response and acoustic field due to solids of different elastic properties and fluids of different impedances;The capability developed for the general problem is extended to a specific application, namely the reflection and transmission of an ultrasonic beam through an open interface. Wave mechanics of this type is an important part of nondestructive ultrasonic immersion testing where the interface is the surface of the component being probed. That surface, if locally flat, can be modelled as a flat half-space or it might have local curvature. Infinite domains, under certain assumptions, are readily approximated with an easy modification of the BEM formulation. The formalism is verified by an exact analysis of a Gaussian beam transmitted through a flat interface and by studying the ability of the solutions to satisfy the elastodynamic reciprocity relations for concave and convex interfaces;Various features of the coupling phenomenon and the BIE formalism are discussed, including instability of the coupled matrix at special eigenfrequencies (fictitious eigenfrequencies). The accuracy to be expected in a scattering problem at or near these frequencies is investigated and illustrated for the case of an elastic sphere in a fluid. Surface wave phenomenon encountered during non-normal incidence on an interface is also analyzed and various aspects of their modelling discussed

Sonochemical Synthesis of Cobalt Ferrite Nanoparticles

Cobalt ferrite being a hard magnetic material with high coercivity and moderate magnetization has found wide-spread applications. In this paper, we have reported the sonochemical synthesis of cobalt ferrite nanoparticles using metal acetate precursors. The ferrite synthesis occurs in three steps (hydrolysis of acetates, oxidation of hydroxides, and in situ microcalcination of metal oxides) that are facilitated by physical and chemical effects of cavitation bubbles. The physical and magnetic properties of the ferrite nano-particles thus synthesized have been found to be comparable with those reported in the literature using other synthesis techniques

Probing non-standard interactions at Daya Bay

In this article we consider the presence of neutrino non-standard interactions (NSI) in the production and detection processes of reactor antineutrinos at the Daya Bay experiment. We report for the first time, the new constraints on the flavor non-universal and flavor universal charged-current NSI parameters, estimated using the currently released 621 days of Daya Bay data. New limits are placed assuming that the new physics effects are just inverse of each other in the production and detection processes. With this special choice of the NSI parameters, we observe a shift in the oscillation amplitude without distorting the L/E pattern of the oscillation probability. This shift in the depth of the oscillation dip can be caused by the NSI parameters as well as by theta(13), making it quite difficult to disentangle the NSI effects from the standard oscillations. We explore the correlations between the NSI parameters and theta(13) that may lead to significant deviations in the reported value of the reactor mixing angle with the help of iso-probability surface plots. Finally, we present the limits on electron, muon/tau, and flavor universal (FU) NSI couplings with and without considering the uncertainty in the normalization of the total event rates. Assuming a perfect knowledge of the event rates normalization, we find strong upper bounds similar to 0.1% for the electron and FU cases improving the present limits by one order of magnitude. However, for a conservative error of 5% in the total normalization, these constraints are relaxed by almost one order of magnitude

Sonochemical Synthesis of Cobalt Ferrite Nanoparticles

Cobalt ferrite being a hard magnetic material with high coercivity and moderate magnetization has found wide-spread applications. In this paper, we have reported the sonochemical synthesis of cobalt ferrite nanoparticles using metal acetate precursors. The ferrite synthesis occurs in three steps (hydrolysis of acetates, oxidation of hydroxides, and in situ microcalcination of metal oxides) that are facilitated by physical and chemical effects of cavitation bubbles. The physical and magnetic properties of the ferrite nano-particles thus synthesized have been found to be comparable with those reported in the literature using other synthesis techniques

Pituitary Gigantism: A Case Report

Objective: To present a rare case of gigantism. Case Report: A 25-year-old lady presented with increased statural growth and enlarged body parts noticed since the age of 14 years, primary amenorrhea, and frontal headache for the last 2 years.She has also been suffering from non-inflammatory low back pain with progressive kyphosis and pain in the knees, ankles, and elbows for the last 5 years. There was no history of visual disturbance, vomiting, galactorrhoea, cold intolerance. She had no siblings. Family history was non-contributory.Blood pressure was normal. Height 221 cm, weight 138 kg,body mass index (BMI)28. There was coarsening of facial features along with frontal bossing and prognathism, large hands and feet, and small goitre. Patient had severe kyphosis and osteoarthritis of knees. Confrontation perimetry suggested bitemporal hemianopia. Breast and pubic hair were of Tanner stage 1. Serum insulin like growth factor-1 (IGF1) was 703 ng/ml with all glucose suppressedgrowth hormone (GH)values of >40 ng/ml. Prolactin was 174 ng/ml. Basal serum Lutenising Hormone (LH), follicle stimulating Hormone (FSH) was low. Oral glucose tolerance test (OGTT), liver and renal function tests, basal cortisol and thyroid profile, Calcium, phosphorus and Intact Parathyroid hormone (iPTH) were normal.Computed tomographyscan of brain showed large pituitary macroadenoma. Automated perimetry confirmed bitemporal hemianopia. A diagnosis of gigantism due to GH secreting pituitary macroadenoma with hypogonadotrophichypogonadism was made. Debulking pituitary surgery followed by somatostatin analogue therapy with gonadal steroid replacement had been planned, but the patient refused further treatment

Bio-transformation of artemisinin using soil microbe: Direct C-acetoxylation of artemisinin at C-9 by Penicillium simplissimum

Potent antimalarial compound artemisinin, 1 was bio-transformed to C-9 acetoxy artemisinin, 2 using soil microbe Penicillium simplissimum along with C-9 hydroxy derivative 3. The products were characterized using high field NMR and MS–MS data. The absolute stereochemistry of the newly generated chiral centers has been ascertained by COSY and 1D NOESY experiments. This is the first Letter of direct C-acetoxylation of artemisinin using microbial strains

Integrated care for type 1 diabetes: The West Bengal model

Introduction: A structured dedicated health programme for Type 1 diabetes mellitus (T1DM) has been initiated in the state of West Bengal, India. Aim: The aim is to provide comprehensive healthcare to all children, adolescents and young adults living with T1DM, along with the provision of free supply of insulin, glucose measuring devices, blood glucose test strips, and other logistics. The strategic framework for programme implementation is to utilise the infrastructure and manpower of the already existing non-communicable disease (NCD) clinic under National Health Mission. Methodology: Establishing dedicated T1DM clinics in each district hospital by utilising existing healthcare delivery systems, intensive training and hand-holding of named human resources; providing comprehensive healthcare service and structured diabetes education to all T1DM patients; and building an electronic registry of patients are important components of the programme. T1DM clinics run once a week on the same day throughout the state. All T1DM patients are treated with the correct dose of insulin, both human regular insulin and glargine insulin. Patients are routinely monitored monthly to ensure good glycaemic control and prevent complications of the disease. Routine anthropometric examination and required laboratory investigations are conducted in the set-up of the already existing NCD clinic. Ongoing monitoring and evaluation of the T1DM programme are being conducted in terms of glycated haemoglobin (HbA1c) values, growth and development, complication rates, psychological well-being, quality of life, and direct and indirect expenditure incurred by families. Through this programme, any bottlenecks or gaps in service delivery will be identified and corrective measures will be adopted to ensure better health outcomes for those living with T1DM