Analysis of metallurgical aspects and their role in processing and performance of superalloys: A review

Metallurgical processing factors like kinetic and thermodynamic parameters which are essential for modeling of γ′ phase precipitation have been studied. These parameters include γ′ solvus temperature, Gibbs free energy of dissociation of the γ matrix to form γ′, nucleation rate, effective diffusivity and interfacial energy. Nucleation methods and effect of cooling rate on the final phase structure have been analyzed. Co based  superalloys have been studied as a potential and promising material for aerospace applications. Effect of microporosity on the mechanical properties of Superalloys has also been analyzed.Keywords: Superalloys, Precipitation, Solidification, Gamma prime, Microsegregation, Microporosity

Studying the effect of variation in volume fractions of carbon fibres on mechanical and electrical properties of copper based composites

Metal Matrix Composites (MMC) belong to a class of weight efficient structural materials that are becoming popular in engineering applications especially in electronics, aerospace, aircraft, packaging and various other industries. This study focuses on the effect of varying carbon fiber wt. % on the mechanical properties of the Cu-C composite. The carbon fibers were coated with copper by electroless plating in order to increase the wettability of fibers with the copper matrix. Four compositions of copper based composite were developed by varying amount of carbon fibers. The yield strength decreases with increasing fiber size while the ultimate  tensile strength increases with increasing fiber size. Rockwell hardness test showed an increasing trend of hardness for increasing carbon fibers. The conductivity of Cu-C composite decreases by increasing carbon fibers content. Wear rate of Cu-C composite increases when carbon fiberscontent increases in the composite. SEM/EDX analysis revealed the size and distribution of fibers and indicated the fracture phenomenon.Keywords: Copper based Composites, Mechanical, Electrical and Wear Properties, Microstructur

Fast and Memory-Efficient Key Recovery in Side-Channel Attacks

Abstract. Side-channel attacks are powerful techniques to attack imple-mentations of cryptographic algorithms by observing its physical param-eters such as power consumption and electromagnetic radiation that are modulated by the secret state. Most side-channel attacks are of divide-and-conquer nature, that is, they yield a ranked list of secret key chunks, e.g., the subkey bytes in AES. The problem of the key recovery is then to find the correct combined key. An optimal key enumeration algorithm (OKEA) was proposed by Charvil-lon et al at SAC’12. Given the ranked key chunks together with their probabilities, this algorithm outputs the full combined keys in the opti-mal order – from more likely to less likely ones. OKEA uses plenty of memory by its nature though, which limits its practical efficiency. Espe-cially in the cases where the side-channel traces are noisy, the memory and running time requirements to find the right key can be prohibitively high. To tackle this problem, we propose a score-based key enumeration algo-rithm (SKEA). Though it is suboptimal in terms of the output order of cadidate combined keys, SKEA’s memory and running time requirements are more practical than those of OKEA. We verify the advantage at the example of a DPA attack on an 8-bit embedded software implementation of AES-128. We vary the number of traces available to the adversary and report a significant increase in the success rate of the key recovery due to SKEA when compared to OKEA, within practical limitations on time and memory. We also compare SKEA to the probabilistic key enumera-tion algorithm (PKEA) by Meier and Staffelbach and show its practical superiority in this case. SKEA is efficiently parallelizable. We propose a high-performance solu-tion for the entire conquer stage of side-channel attacks that includes SKEA and the subsequent full key testing, using AES-NI on Haswell Intel CPUs. 2 A. Bogdanov et al

HEPATOPROTECTIVE EFFECT OF Solanum nigrum LEAVE DIETHYL ETHER EXTRACT ON LIVER CCl4 TOXICITY

Solanum nigrum is a medicinal plant commonly known as black night shade and Makoi, it is found in two varieties. One has black colored fruits while the other has reddish brown colored fruit. Traditionally Solanum nigrum possesses a number of active compounds which are responsible for its diverse pharmacological properties. The current study aims to investigate the diethyl ether extract of Solanum nigrum leaves activity on the liver acute toxicity induced by carbon tetrachloride in rabbits. The rabbits were allocated randomly into two groups (n=6). The hepatic damage intensity and protection was observed by biochemically investigating the serum levels of Lactate dehydrogenase (LDH), bilirubin, Alanine transaminase (ALT), Asparate transaminase (AST), alkaline phosphatase (ALP), total protein (TP) and tissue histopathology analysis. The results showed that the diethylether extract of Solanum nigrum leaves have significant (p < 0.05) shielding effect on all hepatic enzymes and protein. Histopathological evaluation also confirmed that diethyl ether extract of leaves has potential to protect the liver against chemical (CCL4) induced injury.&nbsp

Thermal, electrochemical and mechanical properties of shape memory alloy developed by a conventional processing route

A Cu based shape memory alloy (Cu-Al-Ni) having a composition 83% Cu, 14% Al, 3% Ni, was developed and studied to determine the shape memory effect. Powder of Cu, Al and Ni was melted in a pit furnace at about 15500C, and casted alloy was heat treated at 8500C for a period of 50 minutes followed by water quenching. Microstructure characterization of alloy (Cu-Al-Ni) was carried out to determine the pre-quenched (cast structure) and quenched martensitic structure. The microstructure analysis of developed samples showed needle like structure of quenched martensite after heat treatment. It has a very good resemblance with structure of casted shape memory alloy obtained from the vacuum induction process. The Vickers hardness test was also performed. Quenched microstructure with improved hardness than pre-quenched structure was observed.Keywords: Shape Memory Alloy, Microstructure, Mechanical Propertie

THE DEVELOPMENT AND CHARACTERIZATION OF GLASS FIBER-SILICA SAND NANOPARTICLES REINFORCED HYBRID COMPOSITES

Metal matrix composites are a unique class of weight efficient structural materials that are encouraging every field of engineering applications especially aerospace and automobile industries. The present study focused on the development of the silica sand nanoparticles-glass fiber reinforced aluminium based hybrid composites. Composites were developed by compocasting method using 1.5, 2.5, 3.5 and 4.5 wt. % of silica sand nanoparticles and glass fibers. Variation in tensile properties was evaluated using universal testing machine and the hardness profiles were measured using Micro Hardness Tester (HMV). A significant improvement in tensile strength and micro hardness was observed. However a decrease in impact strength was observed with increase in reinforcement. The homogenous dispersion of silica sand nanoparticles and pulling of glass fibers from the aluminium matrix was verified using Scanning Electron Microscope (SEM).&nbsp

Acute COPD exacerbation presenting with pronounced intrabullous haemorrhage and haemoptysis

A 54-year-old man with history of chronic obstructive pulmonary disease (COPD) presented with subacute onset of chest pain, shortness of breath, productive cough with haemoptysis and night sweats. There were no fever or recent weight loss reported. The chest radiograph showed right upper lobe bullae with adjacent opacification and an emphysematous lung. Due to worsening haemoptysis and persistent chest pain, CT of the chest with contrast was performed, which revealed moderate to severe emphysema and numerous blood-filled bullae. Cardiac work-up for chest pain was negative for myocardial ischaemia and for aortic dissection. Further infectious work-ups for mycobacterial and invasive fungal infection were negative. The patient was treated for acute COPD exacerbation and responded well to the antibiotics with the resolution of haemoptysis. Follow-up CT of the chest revealed the gradual resolution of the haemorrhage, while the patient remained asymptomatic. KEYWORDS: pulmonary emphysema; tobacco related diseas