Uptake of α-Linolenic Acid and Its Conversion to Long Chain Omega-3 Fatty Acids in Rats Fed Microemulsions of Linseed Oil

The present work was designed to prepare linseed oil (LSO) microemulsion and explore the possibility of enhancing the uptake and utilization of α-linolenic acid (ALA) present in LSO. The bioavailability of encapsulated LSO as against native oil was monitored in rats by measuring the uptake in vitro using the intestinal everted sac model and in-vivo administration of microemulsions of LSO to rats for a period of 30?days. Microemulsions were prepared by using different binding materials such as gum acacia, whey protein and lipoid. When LSO was encapsulated with gum acacia, whey protein and lipoid, the levels of ALA uptake into intestinal sacs was increased by 6, 17 and 28?% as compared to oil given without encapsulation. EPA and DHA were not observed in the oil absorbed by intestinal everted sacs when given as emulsions with gum acacia or whey protein. When LSO was given as microemulsions with lipoid, EPA?+?DHA was observed in oil absorbed by intestinal sacs. Similarly when LSO was given as a lipoid emulsion by intubation to rats, the EPA and DHA in serum lipids were found to be 41 and 34?μg/ml, respectively while rats given LSO without encapsulation contained EPA and DHA at 9.1 and 8.8?μg/ml, respectively. Similar changes in omega-3 fatty acid content in liver lipids were observed when LSO was given as a microemulsion with lipoid. This study indicated that ALA was taken up and metabolized to long chain omega-3 PUFA when given as microemulsion with lipoid.     

A novel approach for evaluation of polymeric interface materials for chemical sensors using alternate indirect methods

The heart of a chemical sensor based on bulk or surface acoustic wave devices is a polymer‐coated piezoelectric substrate that selectively sorbs and concentrates the target analyte vapors. The development of such sensors often necessitates the screening and evaluation of suitable polymeric interface materials meeting the specified sensitivity and selectivity toward the analytes of interest. The magnitude and dynamics of sorption–desorption of the vapors in the polymer and the extent of polymer–vapor interactions largely determine the performance of a sensor. The standard protocol used for the purpose is rather tedious, involving the generation and calibration of individual analyte vapors, with stringent control on temperature, humidity, and test parameters. This article outlines four different alternative techniques based on mass uptake of the analyte vapors, on its partitioning in polymers, or both, which in combination can determine the characteristics of an interface material used for coating a piezoelectric substrate in acoustic wave‐based chemical sensors. These methods were applied to poly(ethylene maleate), a representative interface material. The analytes ranged from volatile organic chemicals to sarin—a chemical warfare agent—and its simulant, dimethyl methylphosphonate. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3428–3432, 2004     

Fatigue life prediction analysis of surface cracked straight pipes

In piping components, for the stability assessment it is important to calculate the point of initiation of the crack and to monitor the subsequent crack propagation behaviour. The objective of this paper is to use the finite element method backed up with experimental results to determine the crack initiation stage and to subsequently predict the crack propagation behaviour under fatigue loading. With reference to full scale surface cracked carbon steel pipes tested data, the accuracy of the numerical procedure is judged. It is concluded that semi-elliptical SIFs solutions should not be used to assess the fatigue life when straight pipe is having constant depth crack profile.     

Modified circular common element four‐port multiple‐input‐multiple‐output antenna using diagonal parasitic element

A four‐port multiple input multiple‐output (MIMO) antenna with common radiating element is proposed for 2.4 GHz Wi‐Fi applications. It comprises a modified circular radiator fed by four identical modified feedlines, partial ground planes, and a diagonal parasitic element (DPE). The parasitic element is used to enhance the interport isolation. The antenna has a 2:1 Voltage standing wave ratio (VSWR) impedance band 2.34‐2.56 GHz and nearly omnidirectional radiation patterns. The radiation efficiency is more than 79% and gain is 2 dBi at resonant 2.43 GHz. The isolation in the given frequency band is 10 dB. At the 2.43 GHz, the isolation between adjacent ports (1, 2 and 1, 4) is 14 dB and between opposite ports (1, 3) is 12 dB. The mean effective gain (MEG) ≤ ?2.7 dB and envelope correlation coefficient is <0.01. The ?10 dB total active reflection coefficient bandwidth is 202 MHz. The antenna is designed for a Wi‐Fi device and the effectiveness of antenna has been checked for distance of ½ feet from the human head. The specific absorption rate (SAR) is found to be ≤0.17 W/Kg by CST simulation tool.     

Hot Deformation Behavior of As-Cast 2101 Grade Lean Duplex Stainless Steel and the Associated Changes in Microstructure and Crystallographic Texture

The hot deformation behavior of 2101 grade lean duplex stainless steel (DSS, containing ~5 wt pct Mn, ~0.2 wt pct N, and ~1.4 wt pct Ni) and associated microstructural changes within δ-ferrite and austenite (γ) phases were investigated by hot-compression testing in a GLEEBLE 3500 simulator over a range of deformation temperatures, T _def [1073 K to 1373 K (800 °C to 1100 °C)], and applied strains, ε (0.25 to 0.80), at a constant true strain rate of 1/s. The microstructural softening inside γ was dictated by discontinuous dynamic recrystallization (DDRX) at a higher T _def [1273 K to 1373 K (1000 °C to 1100 °C)], while the same was dictated by continuous dynamic recrystallization (CDRX) at a lower T _def (1173 K (900 °C)]. Dynamic recovery (DRV) and CDRX dominated the softening inside δ-ferrite at T _def ≥ 1173 K (900 °C). The dynamic recrystallization (DRX) inside δ and γ could not take place upon deformation at 1073 K (800 °C). The average flow stress level increased 2 to 3 times as the T _def dropped from 1273 to 1173 K (1000 °C to 900 °C) and finally to 1073 K (800 °C). The average microhardness values taken from δ-ferrite and γ regions of the deformed samples showed a different trend. At T _def of 1373 K (1100 °C), microhardness decreased with the increase in strain, while at T _def of 1173 K (900 °C), microhardness increased with the increase in strain. The microstructural changes and hardness variation within individual phases of hot-deformed samples are explained in view of the chemical composition of the steel and deformation parameters (T _def and ε).

     

Rats fed linseed oil in microemulsion forms enriches the cardiac sarcoplasmic reticulum lipids with docosahexaenoic acid and lower calcium transport

The effect of feeding rats with whey protein or lipoid microemulsion of n-3 rich linseed oil (LSO), and n-6 rich sunflower oil (SNO) compared to native or microemulsion forms of each oil for 60 days on fatty acid composition, Ca²⁺Mg²⁺ ATPase, Ca²⁺ uptake and membrane fluidity of rat cardiac sarcoplasmic reticulum (SR) were assessed. Rats consuming LSO in lipoid microemulsion showed higher levels of ALA (18:3, n-3) conversion to DHA (22:6, n-3) when compared to rats given LSO in native form. Compared to all other dietary treatments, the alterations in the n-6/n-3 PUFA composition of SR of rats given LSO in lipoid microemulsion effected the greatest changes in Ca²⁺Mg²⁺ ATPase activity and Ca²⁺ uptake which effectively reduced Ca²⁺ transport. Therefore, the LSO in lipoid microemulsion confers similar heart healthy fatty acid compositional and calcium transport changes and potentially anti-arrhythmic effects similar to fish oils.     

Establishing a methodology to predict the crack initiation load in through-wall cracked components using tensile specimen test data

Among several other definitions, the crack initiation fracture toughness (J_i) based on critical stretch zone width (SZWc), called J_SZWc, is being considered as a geometry independent material property. The problem in SZWc experimental evaluation is in identifying the size of stretch zone on a blunted crack front as this requires a high degree of precision and expertise in measuring the SZW. The present study addresses finite element determination of SZWc value using tensile test data. The role of stress tri-axiality in standard fracture specimens and the smooth round tensile specimen is also studied. Based on the ASTM-E1820 standard, the present study also showed that fracture specimen thickness greater than the specified size is to be used for numerical prediction of valid SZWc value. The numerically predicted SZWc that leads to J_SZWc matches well with experimental values. Using J_SZWc, the crack initiation load is also determined in circumferentially through-wall cracked (TWC) elbows and compares well with experimental results. Thus the paper establishes the methodology to predict crack initiation in cracked piping components using numerically obtained valid J_SZWc from material’s tensile test data.     

N-nitrosamines formation from secondary amines by nitrogen fixation on the surface of activated carbon

Our previous study demonstrated that many commercial activated carbon (AC) particles may catalyze transformation of secondary amines to yield trace levels of N-nitrosamines under ambient aerobic conditions. Because of the widespread usage of AC materials in numerous analytical and environmental applications, it is imperative to understand the reaction mechanism responsible for formation of nitrosamine on the surface of ACs to minimize their occurrence in water treatment systems and during analytical methods employing ACs. The study results show that the AC-catalyzed nitrosamine formation requires both atmospheric oxygen and nitrogen. AC's surface reactive sites react with molecular oxygen to form reactive oxygen species (ROS), which facilitate fixation of molecular nitrogen on the carbon surfaces to generate reactive nitrogen species (RNS) likely nitrous oxide and hydroxylamine that can react with adsorbed amines to form nitrosamines. AC's properties play a crucial role as more nitrosamine formation is associated with carbon surfaces with higher surface area, more surface defects, reduced surface properties, higher O(2) uptake capacity, and higher carbonyl group content. This study is a first of its kind on the nitrosamine formation mechanism involving nitrogen fixation on AC surfaces, and the information will be useful for minimization of nitrosamines in AC-based processes.     

Simulation of steam reforming of biogas in an industrial reformer for hydrogen production

The paper aims to investigate the steam reforming of biogas in an industrial-scale reformer for hydrogen production. A non-isothermal one dimensional reactor model has been constituted by using mass, momentum and energy balances. The model equations have been solved using MATLAB software. The developed model has been validated with the available modeling studies on industrial steam reforming of methane as well as with the those on lab-scale steam reforming of biogas. It demonstrates excellent agreement with them. Effect of change in biogas compositions on the performance of industrial steam reformer has been investigated in terms of methane conversion, yields of hydrogen and carbon monoxide, product gas compositions, reactor temperature and total pressure. For this, compositions of biogas (CH₄/CO₂ = 40/60 to 80/20), S/C ratio, reformer feed temperature and heat flux have been varied. Preferable feed conditions to the reformer are total molar feed rate of 21 kmol/h, steam to methane ratio of 4.0, temperature of 973 K and pressure of 25 bar. Under these conditions, industrial reformer fed with biogas, provides methane conversion (93.08–85.65%) and hydrogen yield (1.02–2.28), that are close to thermodynamic equilibrium condition.     

Effect of blending and lipase catalyzed interesterification reaction on the cholesterol lowering properties of palm oil with rice bran oil in rats

The effect of feeding blended and interesterified oils containing palm oil (PO) and rice bran oil (RBO) on serum and liver lipids was evaluated in rats. The PO and RBO were blended to contain saturated, monounsaturated and polyunsaturated fatty acids in the proportion of 1:1.5:1. The blended oil was subjected to transesterification reaction using immobilized lipase, lipozyme IM‐RM. Rats were fed a diet containing blended or interesterified oils for 8 weeks. Rats fed PO showed significantly higher levels of cholesterol in serum and liver as compared to those given RBO, blended oil of PO with RBO or interesterified oil. Rats fed blended oils showed a significant decrease in serum cholesterol by 51% compared to rats fed PO. Feeding interesterified oil to rats resulted in decrease in serum cholesterol by 56% compared to rats fed PO, which was 10% lower compared to that observed in rats given blended oil. The present study indicated that a combination of PO with RBO can significantly lower serum lipids in rats as compared to those given diet containing PO alone.