Solubility Enhancement of Atorvastatin Calcium Using Cyclodextrin

The present study is intended to increase the solubility and dissolution rate of Atorvastatin calcium (ATN Ca) by formulating the drug- hydroxy-propyl-beta cyclodextrin (HPBCD) complexes using solvent-assisted extrusion (SAE) using a twin-screw extruder. Various studies on ATN Ca saturation solubility in water and other pH mediums revealed a pH-dependent solubility with a difference. Thus, the saturation solubility for ATN Ca and Solvent Assisted Extruded complex was conducted in water and different pH mediums in this study. Phase solubility studies between ATN Ca and CDs revealed an AL-type solubility profile exhibiting a linear increase with HPBCD. Drug-HPBCD complexes were made using the solvent-assisted extrusion (Twin Screw Extruder) procedure and conventional techniques, including physical mixing and the kneading method. The solubility of the SAE complexes, as compared to normal ATN Ca (0.0167 mg/mL), was 0.294 mg/mL, respectively. Differential scanning calorimetry and Fourier transform infrared spectroscopy analyses were used to confirm the formation of drug-cyclodextrin inclusion complexes. The formulated products were filled into #2 clear gelatin capsules for better dissolution. According to tests on drug release at 5 min, 10 min, 15 min, and 30 min time intervals, ATN Ca was released at the highest rate from solvent-assisted extruded complex (103 %) compared to other samples. When compared to the drug release from complexes formed by kneading was much lower (89 %). All these studies show promising results to conclude that the complex formed through solvent-assisted extrusion (SAE) has enhanced the solubility and dissolution rate of the Atorvastatin Calcium

Examining Stress Relaxation in a Dissimilar Metal Weld Subjected to Postweld Heat Treatment

Dissimilar metal welds are often required in nuclear power plants to join components made from austenitic steels to those from ferritic steels, particularly in fast breeder reactor plants, in order to join the intermediate heat exchanger to the steam generator. The process of welding alters the microstructure of the base materials and causes residual stresses to form, both because of the change in the microstructure and the differing thermal histories in various regions. Postweld heat treatment (PWHT) is required to relieve the residual stresses and achieve preferable microstructural gradients across the weld joint. Therefore, in order to arrive at the optimal PWHT process, it is necessary to investigate the effects of heat treatment on the joint integrity, microstructure, and residual stress relaxation in the welds. To investigate the effect of PWHT on the residual stress relaxation and corresponding alteration of microstructure across a welded joint, a dissimilar weld between modified 9Cr-1Mo steel and austenitic stainless steel AISI 316LN was made using autogenous electron beam welding. To achieve this, the welding process was first modeled numerically using finite element analysis, and the residual stress predictions were validated by experimental investigation using neutron diffraction. The validated model was then used to study the residual stress relaxation through the simulation of PWHT. The predicted stress relaxation was compared with contour method measurement of residual stresses in the actual welded plate subjected to PWHT. The results indicate that, although some relaxation of residual stresses occurred during PWHT, there is still a significant portion of highly localized residual stresses left in the specimen

APPLICATION OF AI/ML TECHNIQUES TO CREATE CONFIDENCE/TRUST SCORE TO PROTECT USERS AGAINST PHISHING ATTACKS

Existing methods to prevent phishing attacks in enterprise environments typically rely on employees being vigilant with regard to email and/or internet use. However, as employees juggle to work on multiple priorities, sometimes they fall prey to targeted phishing attacks. Presented herein are techniques through which data can be pulled from multiple sources and analyzed using AI/ML techniques in order to predict potential phishing attacks for users across multiple mediums

Secure and Reliable Deep Space Networks

Satellite systems have the advantage of global coverage and inherent broadcast capability and offer a solution for providing broadband access to end users. The main thrust of space communications to-date has been to provide reliable communications between ground mission control and a single spacecraft. Little work has been reported on developing a secure as well as a reliable mode of communications in a deep space satellite network. Our main objective is to develop an algorithm that can increase the reliability (such as in terms of minimum energy consumption) and security in the communications path while minimizing overheads. We realize this by assigning costs to every node and links in the path and then optimally selecting a path with the lowest cost that is also secure. We develop an algorithm to efficiently compute a secure and reliable communications path at minimum cost. The proposed approach is compared to a shortest path approach. Simulation results indicate that although the proposed approach yields slightly longer paths, it provides a more efficient approach in terms of energy distribution as well as secure paths.Computer Science Departmen

A method for reconstruction of residual stress fields from measurements made in an incompatible region

AbstractA method is introduced by which the complete state of residual stress in an elastic body may be inferred from a limited set of experimental measurements. Two techniques for carrying out this reconstruction using finite element analysis are compared and it is shown that for exact reconstruction of the stress field via this method, the stress field must be measured over all eigenstrain-containing regions of the object. The effects of error and incompleteness in the measured part of the stress field on the subsequent analysis are investigated in a series of numerical experiments using synthetic measurement data based on the NeT TG1 round-robin weld specimen. It is hence shown that accurate residual stress field reconstruction is possible using measurement data of a quality achievable using current experimental techniques

Characterising Residual Stresses in a Dissimilar Metal Electron Beam Welded Plate

AbstractDissimilar metal welded components are becoming increasingly common in industrial applications especially in the nuclear sector. Dissimilar metal welding refers to the joining of two materials from different alloy groups. One of the basic requirements of the dissimilar metal welded joint is that the joint strength should be greater than or equal to that of the weakest member and a careful characterisation of the joint is crucial before considering the applicability of the dissimilar metal welded components. The current paper explores the feasibility of an electron beam welded joint between ferritic/martensitic Grade 91 or more commonly known as modified P91 and austenitic 316LN stainless steel, without the addition of any filler material. The residual stress distribution arising from the welding is determined from measurements using neutron diffraction experiment and predictions using finite element analysis. The measured data has been analysed using Rietveld and single peak fits. The finite element analysis was conducted on a two-dimensional cross-sectional model using ABAQUS code, implementing the effects of solid-state phase transformation experienced by P91 steel. The predicted residual stresses are compared with the experimental measurements and conclusions are drawn on the final residual stress distribution

Applying electron backscattering diffraction to macroscopic residual stress characterisation in a dissimilar weld

AbstractDissimilar metal welds are complicated in nature because of the complex microstructure characteristics in the weld fusion zone. It is often necessary to know the phase distribution in a dissimilar metal weld especially at the interface such as fusion zone and heat affected zone to be able to predict the behaviour of the joint and its fitness for service. In this paper, a dissimilar metal weld made between ferritic/martensitic modified 9Cr-1Mo steel (P91) and austenitic AISI 316LN stainless steel using autogenous electron beam (EB) welding was analysed. The weld fusion zone has a local segregation of bcc and fcc phases. The EBSD technique was applied to determine the volume fractions of each of these phases in the weld fusion zone. This information was incorporated into the analysis of neutron diffraction data from the weld zone, and the macro-scale residual stresses were calculated from phase-specific stresses arising from the welding process. The results indicate that the overall macroscopic residual stress distribution in the weld centre is predominantly compressive in nature driven by the solid-state phase transformation of the weld pool during rapid cooling, with tensile peaks pushed adjacent to the heat affected zone (HAZ)/Parent boundaries on both sides of the fusion zone