Ultrasonic behavior of plastically deformed and heat treated steel

Studies were made on the longitudinal ultrasonic velocity and its attenuation characteristics in medium carbon steel forging subjected to 0–60% hot upsetting followed by heat treatment. The fineness of ferrite and pearlite increased with increasing deformation and cooling rate during heat treatment. The area fraction of pearlite increased from 21% to 45% as well as the mean interlamellar spacing in pearlite decreased from 8.79 μm to 0.689 μm in the 40% deformed (upsetted) normalized sample It was observed that the ultrasonic velocity decreased with increasing degree of deformation. The velocity was found to be highest in the normalized steel acquiring a value of 5920 m/s and lowest in hardened steel acquiring a value of 4979 m/s. The attenuation decreased with increasing deformation resulting in increased back wall echo heights. The residual stresses on the surface of typical 60% deformed and annealed steel samples using x-ray diffractometry were measured to be — 39.7 MPa (compressive) and — 188.0 MPa (compressive) respectively.     

Nonwoven viscose fabric-polyvinyl alcohol based flexible composite

Development of ecofriendly packaging materials is still a challenging area. Researchers are continuously working to improve the mechanical and barrier properties of the different polymers which are used in the packaging industry. Selection of reinforcement and matrix for any composite are based upon end use applications. The novelty of the work is development of fully biodegradable, flexible, lightweight biocomposite by reinforcing needle punched flexible nonwoven viscose fabric to the PVA solution. The effect of PVA concentration and areal density of viscose fabric on the properties of prepared composite is examined. The composite thus prepared is assessed in terms of mechanical, thermal, breathability, and UV blocking properties. The nonwoven viscose-PVA composite shows excellent improvement in tensile strength of 100% to 300% with respect to PVA film of equivalent concentration for two different areal densities of viscose fabric. The composite also exhibits improved thermal stability and UV blocking property with respect to parent components. However, a reduction in flexibility (with respect to PVA film) as well as breathability (with respect to viscose fabric) of the composite is observed. Based upon the improved performance of the viscose-PVA composite in terms of mechanical properties, UV and water vapor permeability, it seems that the composite has a strong potential for application in the packaging sector as a flexible as well as biodegradable composite.     

An investigation into surface energetics of rice hull ash particles using Inverse Gas Chromatography (IGC)

Silanol groups that are present on the surface of rice hull ash or silica ash fillers can positively influence the reinforcing character of the filler. However, being hydrophilic, they present the problem of aggregation and moisture absorption. Physicochemical contributions to reinforcement, provided by silanol groups, influence the filler-polymer and filler-filler interactions. In this study, we investigated the surface energetics of silica ash particles and the effect of chemical surface modification on the free surface energy of silica ash particles was studied.Inverse Gas Chromatography (IGC), a successful evaluation technique for the surface energy of solids, has been used at infinite dilution to determine the nature of surface interaction of various probes with a silica ash surface. The Gibbs free energies and enthalpies of specific interactions were also determined to estimate the acid-base characteristics of the surface of silica ash particles. The influence of heat treatment and surface modification upon the physicochemical parameters was also investigated. It was found that the silica ash surface is acidic in nature. Modification of the surface, by hydrophobization using silane agents, reduces the specific component of surface energy and could be expected to positively affect the reinforcing character. Surface modification reduced the specific component of surface energy by 80% and positively affects the filler-matrix interaction.     

Temperature-dependent formation of a conjugate between tris(hydroxymethyl)aminomethane buffer and the malondialdehyde-DNA adduct pyrimidopurinone

OBJECTIVE: To examine the effects of cardiopulmonary bypass (CPB) on total and unbound plasma concentrations of propofol and midazolam when administered by continuous infusion during cardiac surgery. DESIGN: Prospective clinical study. SETTING: University hospital. PARTICIPANTS: Twenty-four adult patients undergoing cardiac surgery. INTERVENTIONS: Patients received either propofol or midazolam to supplement fentanyl anesthesia. Twelve patients received a propofol bolus (1 mg/kg) followed by an infusion of 3 mg/kg/hr. A second group received midazolam, 0.2 mg/kg bolus, followed by an infusion of 0.07 mg/kg/hr. MEASUREMENTS AND MAIN RESULTS: Blood sample were collected from the radial artery cannula at 0, 2, 4, 8, 8, 10, 15, 20 minutes and then every 10 minutes before CPB, at 1, 2, 3, 4, 6, 10, 15, 20 minutes and then each 10 minutes during CPB. On weaning from CPB samples were collected at 0, 5, 10 and 20 minutes. Plasma binding, total and unbound propofol and midazolam concentrations were determined by ultrafiltration and high-pressure liquid chromatography (HPLC). CPB resulted in a fall in total propofol and midazolam plasma concentrations, but the unbound concentrations remained stable. The propofol unbound fraction increased from 0.22 +/- 0.06% to 0.41 +/- 0.17%. The midazolam unbound fraction increased from 5.6 +/- 1.0% to 11.2 +/- 2.1%. CONCLUSIONS: Unbound concentrations of propofol and midazolam are not affected by cardiopulmonary bypass. Total intravenous anesthesia algorithms do not need to be changed to achieve stable unbound plasma concentrations when initiating CPB.     

Interplay Between Superconductivity and Antiferromagnetism in HoNi2B2C

A microscopic theory of interplay between superconductivity and antiferromagnetism in rare-earth nickel boride, HoNi₂B₂C is developed from first principles. Self-consistent equations for the superconducting order parameter Δ and magnetic order parameter Γ are derived using a Green’s function technique and an equation of motion method. The theory is applied to explain the experimental results in the antiferromagnetic superconductor HoNi₂B₂C. The present model explains the true coexistence of superconductivity and antiferromagnetism in this system. The behavior of the superconducting order parameter (Δ), the magnetic order parameter (Γ), the specific heat, the density of states, the free energy and critical field (H _c) is also studied for the system HoNi₂B₂C. Distinct features of the coexistence region are discussed. There is the convincing evidence that the theory is fully compatible with the key experiments.     

Morphological,Mechanical Property Analysis and Comparative Study over Structural Properties of CVD TiN Film Grown under Different Substrate Temperature in Nitrogen Gas Atmosphere

Silicon - Titanium Nitride (TiN) thin films were deposited by thermal chemical vapor deposition process (CVD) over Si (100) substrate under different substrate temperatures. Morphological,...