Analytical study of nuclear-coupled density-wave instability in a natural circulation pressure tube type boiling water reactor

An analytical model has been developed to study the nuclear-coupled density-wave instability in the Indian advanced heavy water reactor (AHWR) which is a natural circulation pressure tube type boiling water reactor. The model considers a point kinetics model for the neutron dynamics and a lumped parameter model for the fuel thermal dynamics along with the conservation equations of mass, momentum and energy and equation of state for the coolant. In addition, to study the effect of neutron interactions between different parts of the core, the model considers a coupled multipoint kinetics equation in place of simple point kinetics equation. Linear stability theory was applied to reveal the instability of in-phase and out-of-phase modes in the boiling channels of the AHWR. The results indicate that the stability behavior of the reactor is greatly influenced by the void reactivity coefficient, fuel time constant, radial power distribution and channel inlet orificing. The delayed neutrons were found to have a strong influence on the Type I and Type II instabilities observed at low and high channel powers, respectively. Also, it was found that the coupled multipoint kinetics model and the modal point kinetics model predict the same threshold power for out-of-phase instability if the coupling coefficient in the former model is half the eigen value separation between the fundamental and the first harmonic mode in the latter model. Decay ratio maps were predicted considering various operating parameters of the reactor, which are useful for its design.     

High-mobility strained-Si PMOSFET's

Operation and fabrication of a new high channel mobility strained-Si PMOSFET are presented. The growth of high-quality strained Si layer on completely relaxed, step-graded, SiGe buffer layer is demonstrated by gas source MBE. The strained-Si layer is characterized by double crystal X-ray diffraction, photoluminescence, and transmission electron microscopy. The operation of a PMOSFET is shown by device simulation and experiment. The high-mobility strained-Si PMOSFET is fabricated on strained-Si, which is grown epitaxially on a completely relaxed step-graded Si_0.82Ge_0.18 buffer layer on Si(100) substrate. At high vertical fields (high |V_g|), the channel mobility of the strained-Si device is found to be 40% and 200% higher at 300 K and 77 K, respectively, compared to those of the bulk Si device. In the case of the strained-Si device, degradation of channel mobility due to Si/SiO₂ interface scattering is found to be more pronounced compared to that of the bulk Si device. Carrier confinement at the type-II strained-Si/SiGe-buffer interface is clearly demonstrated from device transconductance and C-V measurements at 300 K and 77 K     

Hole mobility enhancement in strained-Si p-MOSFETs under high vertical field

The growth of a high quality, step-graded lattice-relaxed SiGe buffer layer on a Si(100) substrate is investigated. p-MOSFETs were fabricated on strained-Si grown on top of the above layer. Carrier confinement at the type-II strained-Si/SiGe buffer interface is observed clearly from the device transconductance and C-V measurements. At high vertical field, compared to bulk silicon, the channel mobility of the strained-Si device with x=0.18 is found to be about 40% and 200% higher at 300 K and 77 K respectively. Measurements on transconductance enhancement are also reported. Data at 77 K provide evidence of two channels and a large enhancement of mobility at high transverse field.     

Synthesis and Biological Evaluation of Benzo[b]furans as Inhibitors of Tubulin Polymerization and Inducers of Apoptosis

A series of benzo[b]furans was synthesized with modification at the 5‐position of the benzene ring by introducing C‐linked substituents (aryl, alkenyl, alkynyl, etc.). These compounds were evaluated for their antiproliferative activities, inhibition of tubulin polymerization, and cell‐cycle effects. Some compounds in this series displayed excellent activity in the nanomolar range against lung cancer (A549) and renal cell carcinoma (ACHN) cancer cell lines. (6‐Methoxy‐5‐((4‐methoxyphenyl)ethynyl)‐3‐methylbenzofuran‐2‐yl)(3,4,5‐trimethoxyphenyl)methanone ( 26 ) and (E)‐3‐(6‐methoxy‐3‐methyl‐2‐(1‐(3,4,5‐trimethoxyphenyl)vinyl)benzofuran‐5‐yl)prop‐2‐en‐1‐ol ( 36 ) showed significant activity in the A549 cell line, with IC₅₀ values of 0.08 and 0.06 μM , respectively. G₂/M cell‐cycle arrest and subsequent apoptosis was observed in the A549 cell line after treatment with these compounds. The most active compound in this series, 36 , also inhibited tubulin polymerization with a value similar to that of combretastatin A‐4 (1.95 and 1.86 μM , respectively). Furthermore, detailed biological studies such as Hoechst 33258 staining, DNA fragmentation and caspase‐3 assays, and western blot analyses with the pro‐apoptotic protein Bax and the anti‐apoptotic protein Bcl‐2 also suggested that these compounds induce cell death by apoptosis. Molecular docking studies indicated that compound 36 interacts and binds efficiently with the tubulin protein.     

Preparation and performance evaluation of castor oil-based polyurethane prepolymer/polylactide blends

Polylactide (PLA) is an important biodegradable polymer, used for numerous applications ranging from industrial packaging to tissue engineering. However, its inherent brittleness and limited thermal stability have restricted its penetration to niche markets. In this communication, the authors demonstrate that blending of PLA with castor oil-based polyurethane prepolymer (COPUP), with the addition of COPUP, dispersed in the PLA matrix can overcome the inherent brittleness of the matrix polymer. NCO-terminated COPUP was successfully synthesized and subsequently mixed with variable concentration of PLA matrix using melt blending technique. The interfacial compatibilization between COPUP and PLA phase happened by the reaction of ?NCO groups with terminal hydroxyl groups of PLA was confirmed by FT-IR peak deconvolution technique. As indicated by the results of DMA and DSC, the glass transition temperature (T _g) of both PLA and COPUP shifted closer together, indicating that the blend compatibility increased. The tensile properties and notched Izod impact strength of the PLA and toughened PLA are also investigated. With the addition of 30 % COPUP concentration, the elongation at break of the blend reached 377.46 %, and a notched Izod impact 269.62 J m^?1. With improved toughness, the PLA/COPUP blends could be used as replacements for some traditional petroleum-based polymers.     

Effect of extrusion on the antioxidant capacity and color attributes of expanded extrudates prepared from purple potato and yellow pea flour mixes

Abstract: Foods with antioxidant capacity provide protection against cardio‐vascular, certain forms of cancers, and Alzheimer's diseases caused by oxidative damages and contribute health benefits. The effect of extrusion cooking on the antioxidant capacity and color attributes of extruded products prepared from 3 selected formulations of purple potato and yellow pea flours using a co‐rotating twin screw extruder were studied. Expansion ratios of the extruded products varied from 3.93 to 4.75. The total antioxidant capacities (TAC) of the extruded products, using DPPH assay, were 3769 to 4116 μg trolox equivalent/g dry weight sample and not significantly different (P > 0.05) from their respective raw formulations. The total phenolic contents (TP) of the extruded products varied from 2088 to 3766 μg of gallic acid equivalent/g dry weight sample and retained 73% to 83% of the TP from the raw formulations after extrusion. The total anthocyanins contents (TA) in the extrudates were 0.116 to 0.228 mg of malvidin‐3‐glucosides/g dry weight sample. Compared with their raw formulations, significant losses (60% to 70%) of the TA in the extruded products occurred due to extrusion cooking. Browning indices and color attributes such as brightness, chroma, and hue angle agreed with degradation of anthocyanins in the extruded products. However, extrusion cooking retained antioxidant capacities of the raw formulations in the extruded products either in their natural forms or degraded products with radical scavenging activity. This study demonstrated the potential for the production of puffed extruded food products with the improved antioxidant content from colored potatoes and pulse formulations.     

Effect of modified MWCNT on the properties of PPO/LCP blend

In this work we have coated multiwalled carbon nanotubes (MWCNTs) with SiC by solgel process and these modified MWCNTs are dispersed in PPO/LCP blend. The dispersion of these modified MWCNTs are analyzed by FESEM and found to be improved compared to pure MWCNTs. Thermal and mechanical properties of the modified MWCNTs added nanocomposites are higher than that of the pure MWCNTs added nanocomposites. PPO/LCP forms an incompatible blend while addition of unmodified and modified MWCNTs improves the compatibility between the blend partners.     

Study on body mass index, lipid profile and lipid peroxidation status in coronary artery disease

Among the many known risk factors of coronary artery disease (CAD) obesity and hypercholesterolaemia are important ones. Whatever may be the risk factor, the basic pathology of CAD is deposition of altered lipids on the endothelium. One of such altered lipid is oxidatively modified low density lipoprotein (LDL). Lipid peroxidation has been assessed by several methods. Quantitation of malondialdehyde (MDA) by thiobarbituric acid (TBA) method is one of the commonly utilised method in several laboratories. In this study 40 cases of CAD were selected for evaluation. The body mass index (BMI), lipid profile and the level of lipid peroxidation (MDA) were measured. Seventeen cases (42.5%) had normal BMI (20-25), 20 cases (50%) were in the overweight range of BMI (26-30) and only 3 cases (7.5%) were in the obese group with a BMI more than 30. BMI correlated better with the level of total cholesterol (Tc), low density lipoprotein cholesterol (HDLc) and MDA. BMI did not show any correlation with triglyceride (Tg) or high density lipoprotein cholesterol (HDLc). MDA level correlated better with Tc, Tg levels and BMI, poorly correlated with LDLc and in inverse relationship was observed with HDLc.