A parallel tracking method for acoustic radiation force impulse imaging

Radiation force-based techniques have been developed by several groups for imaging the mechanical properties of tissue. Acoustic Radiation Force Impulse (ARFI) imaging is one such method that uses commercially available scanners to generate localized radiation forces in tissue. The response of the tissue to the radiation force is determined using conventional B-mode imaging pulses to track micron-scale displacements in tissue. Current research in ARFI imaging is focused on producing real-time images of tissue displacements and related mechanical properties. Obstacles to producing a real-time ARFI imaging modality include data acquisition, processing power, data transfer rates, heating of the transducer, and patient safety concerns. We propose a parallel receive beamforming technique to reduce transducer heating and patient acoustic exposure, and to facilitate data acquisition for real-time ARFI imaging. Custom beam sequencing was used with a commercially available scanner to track tissue displacements with parallel-receive beamforming in tissue-mimicking phantoms. Using simulations, the effects of material properties on parallel tracking are observed. Transducer and tissue heating for parallel tracking are compared to standard ARFI beam sequencing. The effects of tracking beam position and size of the tracked region are also discussed in relation to the size and temporal response of the region of applied force, and the impact on ARFI image contrast and signal-to-noise ratio are quantified.     

Development of Ti-6Al-4V and Ti-1Al-8V-5Fe Alloys Using Low-Cost TiH2 Powder Feedstock

Thermo-mechanical processing was performed on two titanium alloy billets, a beta-titanium alloy (Ti1Al8V5Fe) and an alpha-beta titanium alloy (Ti6Al4V), which had been produced using a novel low-cost powder metallurgy process that relies on the use of TiH₂ powder as a feedstock material. The thermomechanical processing was performed in the beta region of the respective alloys to form 16-mm diameter bars. The hot working followed by the heat treatment processes not only eliminated the porosity within the materials but also developed the preferred microstructures. Tensile testing and rotating beam fatigue tests were conducted on the as-rolled and heat-treated materials to evaluate their mechanical properties. The mechanical properties of these alloys matched well with those produced by the conventional ingot processing route.     

Trends in wetting behavior for Ag–CuO braze alloys on Ba0.5Sr0.5Co0.8Fe0.2O(3−δ) at elevated temperatures in air

In the current study, Ag–CuO, a reactive air brazing alloy was evaluated for brazing Ba_0.5Sr_0.5Co_0.8Fe_0.2O_(3?δ) (BSCF). In situ contact angle tests were performed on BSCF using Ag–CuO binary mixtures at 950 and 1000 °C, and the interfacial microstructures were evaluated. Wetting contact angles (θ < 90°) were obtained at short times at 950 °C, and the contact angles remained constant at 1000 °C for 1, 2, and 8 mol% CuO contents. Microstructural analysis revealed the dissolution of copper oxide into the BSCF matrix to form copper–cobalt–oxygen rich dissolution products along the BSCF grain boundaries. The formation of a thick interfacial reaction product layer and ridging at the sessile drop triple point indicate that the reaction kinetics are very rapid and that it will require careful process control to obtain the desired thin but continuous interfacial product layer.     

New Quaternary Sb-Se-Ge-In Chalcogenide Glasses: Linear and Nonlinear Optical Properties

Chalcogenide glasses find extensive applications in infrared (IR) devices and optical communication. Optical parameters of Sb₁₀Se₆₅Ge_25?y In _y thin films, deposited by the thermal evaporation technique, have been analyzed using ultraviolet–visible-near IR spectroscopy. The transitions in the forbidden gap are indirect. The effect of indium (In) alloying on the nonlinear optical parameters has been studied. A shift in optical absorption edge towards higher wavelength shows that the width of the localized states changes, which affects the optical parameters of the system. The high nonlinearity of these glasses makes them suitable for optical regeneration and Raman amplification.     

A new class of PANI-Ag core-shell nanorods with sensing dimensions

A single-step, cost-effective and eco-safe synthesis of a new class of homogeneous silver-polyaniline (PANI-Ag) core-shell nanorods is carried out via mild photolysis by ultraviolet radiation from sunlight (SUN UV-radiation). X-ray diffraction (XRD) of these core-shell nanorods gives two additional peaks from PANI centered at 2θ = 20.5° and 24. 9°. A validation of the core-shell structural information is given by transmission electron spectroscopy (TEM) whereas the tubular shape morphology is determined by scanning electron microscopy (SEM). UV-Vis. absorption shows a strong blue-shift along with photoluminescence emission. Fourier transform-infrared spectroscopy (FT-IR) and energy dispersive X-ray spectroscopy (EDX) also support the core-shell formation. Thermogravimetric analysis (TGA) shows good thermal stability and allows excellent detection of hydrogen peroxide and hydrazine. The cyclic voltammetry (CV) results show excellent electro-activation, indicating its promising potential in sensing of clinical and environmental analytes.     

Antioxidant potential and radioprotective effect of soy isoflavone against gamma irradiation induced oxidative stress

The in vitro antioxidant potential and in vivo radioprotective ability of soy isoflavones was studied. Male Wistar rats were orally administered with soybean isoflavones (60 mg/kg) for 21 days followed by gamma irradiation exposure. Survival studies in rats exposed at 10 Gy and endogenous spleen colony forming unit assay (CFU) at 6.0 Gy were performed in order to find radioprotective and immunomodulatory nature of the compound. The rat liver post mitochondrial supernatant and erythrocytes were used to measure lipid peroxidation (LPO) and glutathione (GSH) content along with various antioxidant enzymes like superoxide dismutase (SOD), catalase (CAT) and glutathione-S-transferase (GST) after gamma irradiation exposure at 2.0 Gy. Pretreatment with soy isoflavone, prior to gamma irradiation resulted in the increased survival rate of the animals as compared to irradiated group. CFU counts in the isoflavone treated group followed by gamma irradiation at 6 Gy were significantly high as compared to control and the irradiated group, showing immunomodulatory nature of the isoflavones. Pretreatment with isoflavones also significantly reduced the LPO, enhanced the activity of antioxidant enzymes and improved haematological and histological parameters. The present study suggests that supplementation with isoflavone has potent antioxidant activity and act as probable radioprotector against gamma radiation induced oxidative damage.     

Physical Properties of Guar Seeds

A study on the guar seeds (Cyamopsis tetragonoloba) was performed to investigate the effect of moisture content on the selected physical properties. Moisture contents of seeds were varied from 5.2% to 25.0%, dry basis (d.b.). Seed geometric parameters, such as average length, width, thickness, geometric-mean diameter, surface area, volume, increased but sphericity decreased with increase in moisture content. The 1,000-seed mass increased linearly with moisture content. Bulk density of guar seeds decreased linearly when moisture content was raised from 5.2% to 25.0% d.b. On the other hand, true density decreased till moisture content was increased up to 20%. Further increase in seed moisture resulted in increased true density, which has not been observed in other food grains. The porosity decreased till seed 15.3% moisture and then increased with further addition of moisture. Angle of repose, coefficients of static friction on three different surfaces (plywood, mild steel, and galvanized iron), and terminal velocity increased linearly with seed moisture content.     

Physico-Chemical Properties of Immature Pods of Japanese Soybean Cultivars

Twelve Japanese cultivars and JS335, the most popular soybean cultivar in India, were grown in the field. Days to arrival of R6 stage (when pods are still green, immature, and tight with fully developed immature green seeds) of these cultivars were recorded. Pods picked at this stage were evaluated for pod yield per plant, pod characteristics (width, presence of hairs) fresh green seed weight and percent moisture content. Fresh green seeds were analyzed for compositional traits viz. protein content, trypsin inhibitor lipoxygenase isozymes, oil content, and polyunsaturated fatty acids (essential fatty acids). Japanese cultivars showed higher fresh green seed weight and pod yield than JS335. On a fresh weight basis, Japanese cultivars exhibited lower protein content but higher oil content than JS335. Most of the Japanese cultivars showed lower trypsin inhibitor content and a varying level of lipoxygenase-I, as well as lipoxygenase-II + III when compared to JS335. Total polyunsaturated fatty acids content in JS335 was higher than some of the Japanese cultivars. The number of pods per plant showed a positive correlation (r = 0.863, p < 0.001) with pod yield per plant. Some of the Japanese cultivars offer great potential for consumption at the green pod stage or as a source for desirable traits.     

(S)-2-(ethyl propionate)-(O-ethyl xanthate)- and (S)-2-(Ethyl isobutyrate)-(O-ethyl xanthate)-mediated RAFT polymerization of vinyl acetate

(S)-2-(Ethyl propionate)-(O-ethyl xanthate) (X1) and (S)-2-(Ethyl isobutyrate)-(O-ethyl xanthate) (X2) were used as the reversible addition-fragmentation chain transfer (RAFT) agents for the radical polymerization of vinyl acetate (VAc). The former showed the better chain transfer ability in the polymerization at 60°C. Kinetic study with both RAFT agents showed pseudo-first order kinetics up to around 85% monomer conversion. Molecular weight of the resulting polymer increased linearly with increase in the monomer conversion up to around 85%. The observed molecular weights calculated from ¹H-NMR spectrum [M_n(NMR)] are close to the corresponding theoretical molecular weights [M_n(theor)]. The corresponding polydispersity index (PDI) of the resulting polymers remained almost constant at around 1.2 up to ∼ 65% monomer conversion and then increased gradually with the further increase in the monomer conversion. Chain-end analysis of the resulting polymers by ¹H-NMR showed clearly that polymerization started with the radical forming out of the xanthate mediator. The negligible homo-chain extension and the hetero-chain extension involving synthesis of poly(VAc)-b-poly(NVP) diblock copolymer were occurred. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Predicting Guar Seed Splitting by Compression between Two Plates Using Hertz Theory of Contact Stresses

Hertz's theory of contact stresses was applied to predict the splitting of guar seeds during uni-axial compressive loading between 2 rigid parallel plates. The apparent modulus of elasticity of guar seeds varied between 296.18 and 116.19 MPa when force was applied normal to hilum joint (horizontal position), whereas it varied between 171.86 and 54.18 MPa when force was applied in the direction of hilum joint (vertical position) with in moisture content range of 5.16% to 15.28% (d.b.). At higher moisture contents, the seeds yielded after considerable deformation, thus showing ductile nature. Distribution of stresses below the point of contact were plotted to predict the location of critical point, which was found at 0.44 to 0.64 mm and 0.37 to 0.53 mm below the contact point in vertical and horizontal loading, respectively, depending upon moisture content. The separation of cotyledons from each other initiated before yielding of cotyledons and thus splitting of seed took place. The relationships between apparent modulus of elasticity, principal stresses with moisture content were described using second-order polynomial equations and validated experimentally. Practical Application: Manufacture of guar gum powder requires dehulling and splitting of guar seeds. This article describes splitting behavior of guar seeds under compressive loading. Results of this study may be used for design of dehulling and splitting systems of guar seeds.