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Elevated lipoprotein(a) (Lp(a)) is associated with CVD and is mainly genetically determined. Studies suggest a role of dietary fatty acids (FA) in the regulation of Lp(a); however, no studies have investigated the association between plasma Lp(a) concentration and n-6 FA. We aimed to investigate whether plasma Lp(a) concentration was associated with dietary n-6 FA intake and plasma levels of arachidonic acid (AA) in subjects with familial hypercholesterolaemia (FH). We included FH subjects with (n 68) and without (n 77) elevated Lp(a) defined as ≥75 nmol/l and healthy subjects (n 14). Total FA profile was analysed by GC–flame ionisation detector analysis, and the daily intake of macronutrients (including the sum of n-6 FA: 18 : 2n-6, 20 : 2n-6, 20 : 3n-6 and 20 : 4n-6) were computed from completed FFQ. FH subjects with elevated Lp(a) had higher plasma levels of AA compared with FH subjects without elevated Lp(a) (P = 0·03). Furthermore, both FH subjects with and without elevated Lp(a) had higher plasma levels of AA compared with controls (P < 0·001). The multivariable analyses showed associations between dietary n-6 FA intake and plasma levels of AA (P = 0·02) and between plasma levels of Lp(a) and AA (P = 0·006). Our data suggest a novel link between plasma Lp(a) concentration, dietary n-6 FA and plasma AA concentration, which may explain the small diet-induced increase in Lp(a) levels associated with lifestyle changes. Although the increase may not be clinically relevant, this association may be mechanistically interesting in understanding more of the role and regulation of Lp(a).
Among various methods used for the reduction of graphene oxide (GO) into a purer form of graphene, the thermal reduction method provides a simpler, safer, and economic alternative, compared to other techniques. Thermal reduction of GO causes significant weight loss and volume expansion of the material. Current work investigates the onset temperature where reduction in terms of exfoliation takes place, which is determined to be 325 °C at standard atmospheric pressure. Reduction temperature plays the most crucial role as it controls the quality of reduced graphene oxide in terms of weight percentage of carbon and lattice defect. The study leads to achieving highest content with a minimum defect in the graphene lattice at the optimum temperature, which is found to be 350 °C at standard atmospheric pressure. The thermal reduction process has been analyzed with the help of Fourier transform infrared spectroscopy, thermogravimetric analysis, and thermal degradation kinetics. From thermal degradation kinetics of GO, the rate of reaction has been found to be independent of concentration and is a sole function of temperature.
Measurements of local plasma parameters in dusty plasma are crucial for understanding
the physics issues related to such systems. The Langmuir probe, a small electrode
immersed in the plasma, provides such measurements. However, designing of a Langmuir
probe system in a dusty plasma environment demands special consideration. First, the
probe has to be miniaturized enough so that its perturbation on the ambient dust
structure is minimal. At the same time, the probe dimensions must be such that a
well-defined theory exists for interpretation of its characteristics. The associated
instrumentation must also support the measurement of current collected by the probe
with high signal to noise ratio. The most important consideration, of course, comes
from the fact that the probes are prone to dust contamination, as the dust particles
tend to stick to the probe surface and alter the current collecting area in
unpredictable ways. This article describes the design and operation of a Langmuir
probe system that resolves these challenging issues in dusty plasma. In doing so,
first, different theories that are used to interpret the probe characteristics in
collisionless as well as in collisional regimes are discussed, with special emphasis
on application. The critical issues associated with the current–voltage
characteristics of Langmuir probe obtained in different operating regimes are
discussed. Then, an algorithm for processing these characteristics efficiently in
presence of ion-neutral collisions in the probe sheath is presented.
The Proterozoic Sushina Hill Complex is the only agpaitic complex, reported from India and is characterized by a eudialyte-rinkite-bearing nepheline syenite. The complex is considered a ‘metamorphosed agpaitic complex'. This study describes the mineral assemblages formed during successive stages of evolution from magmatic to hydrothermal stages and low-temperature subsolidus re-equilibration assemblage. The primary-late magmatic assemblage is characterized by albite, orthoclase, unaltered nepheline, zoned diopside-hedenbergite, rinkite, late magmatic eudialyte and magnesio-arfvedsonite formed at ∼700°C with maximum aSiO2 of 0.60. In contrast, a deuteric assemblage (400-348°C) is represented by aegirine-jadeite-rich clinopyroxene, post-magmatic eudialyte, sodalite, analcime and the decomposition assemblages formed after eudialyte with decreasing aSiO2 (0.52-0.48). A further low-temperature subsolidus assemblage (≤250°C) represented by late-forming natrolite could be either related to regressive stages of metamorphism or a continuum of the subsolidus processes. Considering the P/T range of the greenschist - lower-amphibolite facies of metamorphism it is evident that the incorporation of a jadeite component within pyroxene is related to a subsolidus process between ∼400°C and 348°C in a silica deficient environment. We emphasize that the deuteric fluid itself acted as an agent of metamorphism and the decomposition assemblage formed after eudialyte is retained even after metamorphism due to the convergence of subsolidus and metamorphic domains. The formation of jadeite-rich aegirine is not considered to result from metamorphism. Overall it is near-impossible to discern any bona fide metamorphic textures or mineral assemblages in these syenites which appear to preserve a relict mineralogy regardless of their occurrence in country rocks which have experienced greenschist - amphibolite facies metamorphism. The Sushina complex is very similar in this respect to the Norra Kärr complex (Sweden).
Intrinsically conductive polymers have received increased attention in the biomedical field due to their mechanical flexibility, electronic and ionic conductivity. On the other hand, bio-derived polymers such as silk proteins (fibroin and sericin) are an important set of materials to realize mechanically deformable, biocompatible and biodegradable systems. Here, we show a ‘green’ approach to fabricate micropatterned, flexible biosensors using photoreactive silk proteins in conjunction with conductive polymers. A functional ink comprised of poly(3,4-ethylene dioxythiophene: poly(styrene sulfonate) (PEDOT:PSS) with silk sericin as a carrier enables the formation of high resolution conducting micropatterns on a silk fibroin substrate via photolithography. The flexible and conformable organic device formed can be used to sense biomolecules with high sensitivity and selectivity. The micropatterned functional silk composites are made using an all water-based fabrication approach, and shown to be cell friendly and degradable. Such systems can find applications in implantable optical devices, bio-sensors, and bio-optoelectronic devices.
We propose a mechanism of highly focused, tunable and high-intensity terahertz (THz) radiation generation by frequency-mixing of two super-Gaussian lasers with frequencies ω1, ω2 and wave numbers k1, k2 (laser profile index p > 2) in a corrugated plasma in the presence of external static magnetic field
. In this process, a strong nonlinear ponderomotive force is offered to the plasma electrons at frequency ω′ = ω1 − ω2 and wave number k′ = k1 − k2 by laser beams. The ponderomotive force results in a strong, controllable nonlinear transverse oscillatory current, which can be optimized by optimizing the external magnetic field, ripple parameters, and laser indexes. This controllable current produces focused and intense THz radiation of tunable frequency and power along with a remarkable efficiency ~25%.
Precise spatial patterns and micro and nanostructures of peptides and proteins have widespread applications in tissue engineering, bioelectronics, photonics, and therapeutics. Optical lithography using proteins provides a route to directly fabricate intricate, bio-friendly architectures rapidly and across a range of length scales. The unique mechanical strength, optical properties, biocompatibility and controllable degradation of biomaterials from silkworms offer several advantages in this paradigm. Here, we present the biochemical synthesis and applications of a “protein photoresist” synthesized from the silk proteins, fibroin and sericin. Using light-activated direct-write processes such as photolithography, we show how silk proteins can form high resolution, high fidelity structures in two and three dimensions. Protein features can be precisely patterned at sub-microscale resolution (µm) at the bench-top over macroscale areas (cm), easily and repeatedly with high-throughput. For instance, periodic, microstructured arrays can be patterned over large areas to form structurally induced iridescent patterns and functional opto-electronic structures. We further demonstrate how photocrosslinked protein micro-architectures can function for the spatial guidance of cells without use of cell-adhesive ligands as biocompatible and biodegradable scaffolds. The ease of biochemical functionalization, biocompatibility, as well as favorable mechanical properties and biodegradation of this silk biomaterial provide opportunities for otherwise inaccessible applications as sustainable, bioresorbable protein microdevices.
In a quasineutral plasma, electrons undergo collective oscillations, known as plasma oscillations, when perturbed locally. The oscillations propagate due to finite temperature effects. However, the wave can lose the phase coherence between constituting oscillators in an inhomogeneous plasma (phase mixing) because of the dependence of plasma oscillation frequency on plasma density. The longitudinal electric field associated with the wave may be used to accelerate electrons to high energies by exciting large amplitude wave. However when the maximum amplitude of the wave is reached that plasma can sustain, the wave breaks. The phenomena of wave breaking and phase mixing have applications in plasma heating and particle acceleration. For detailed experimental investigation of these phenomena a new device, inverse mirror plasma experimental device (IMPED), has been designed and fabricated. The detailed considerations taken before designing the device, so that different aspects of these phenomena can be studied in a controlled manner, are described. Specifications of different components of the IMPED machine and their flexibility aspects in upgrading, if necessary, are discussed. Initial results meeting the prerequisite condition of the plasma for such study, such as a quiescent, collisionless and uniform plasma, are presented. The machine produces δnnoise/n ⩽ 1%, Luniform ~ 120 cm at argon filling pressure of ~10−4 mbar and axial magnetic field of B = 1090 G.
In this paper, mixed convection stagnation point flow of nanofluids over a stretching/shrinking surface is studied numerically in the presence of thermal radiation and viscous dissipation. The governing boundary layer equations are transformed into a system of nonlinear ordinary differential equations, by using a similarity transformation, which are then solved numerically using a fifth-order Runge-Kutta-Fehlberg method with shooting technique. The effects of various physical parameters are analyzed and discussed. Computed results are presented in graphical and tabular forms. It is found that the Richardson number, thermal radiation and internal heat generation/absorption have interesting and significant effects on skin-friction and local Nusselt number for all the three types of nanofluids.
A large outbreak of cholera reported during April–July 2009 in the Kendrapada district of Odisha, India was investigated. Forty-one rectal swabs and 41 water samples, collected from diarrhoeal patients and from different villages were bacteriologically analysed for the isolation of bacterial enteriopathogens, antibiogram profile and detection of various toxic genes. The bacteriological analysis of rectal swabs and environmental water samples revealed the presence of V. cholerae O1 Ogawa biotype El Tor. The V. cholerae strains were resistant to ciprofloxacin, co-trimoxazole, chloramphenicol, streptomycin, ampicillin, furazolidone and nalidixic acid. The multiplex polymerase chain reaction (PCR) assay on V. cholerae strains revealed the presence of ctxA and tcpA genes. The mismatch amplification of mutation assay (MAMA) PCR on clinical and environmental isolates of V. cholerae revealed that the strains were El Tor biotype, which harboured the ctxB gene of the classical strain. The random amplified polymorphic DNA PCR analysis and pulsed-field gel electrophoresis results indicated that the V. cholerae isolates belonged to the same clone. This investigation gives a warning that the El Tor variant of V. cholerae has spread to the coastal district causing a large outbreak that requires close monitoring and surveillance on diarrhoeal outbreaks in Odisha.
Plant protease inhibitors (PI) constitute a major class of defence proteins being selected as an important strategy towards insect herbivory. With the objective of assessing the effect of PI towards larval growth and development, an artificial diet bioassay using partially purified PI obtained from peas was performed on the melon fruit fly Bactrocera cucurbitae (Coquillett). Larval growth and developmental parameters were assessed at different concentrations (namely 12.5, 25, 50, 100, 200 and 400 μg/ml) on the second-instar larvae of B. cucurbitae. Growth and survival responses determined the anti-insect potential of this PI even in its partially purified state. Larval and total development periods were found to be significantly prolonged for the larvae fed on an artificial diet incorporated with pea PI when compared with those fed with a control diet. Furthermore, when compared with the effect of the control diet (no inhibitor), the partially purified pea PI in the diet reduced larval weight gain, mean larval growth rate and food assimilated with respect to the control of the second-instar larvae tested at the same range of concentrations. The relative effectiveness of pea PI on these parameters is in agreement with the results obtained for percentage of pupation and percentage of adult emergence, as these parameters were significantly affected by the increase in the PI concentration in the artificial diet. Feeding the second-instar larvae a diet containing a range of concentrations (50, 100, 200 and 400 μg/ml) of partially purified pea PI significantly reduced the activities of digestive enzymes (trypsin, chymotrypsin, elastase and leucine aminopeptidase) and significantly affected the activities of other non-digestive enzymes (esterase, acid and alkaline phosphatases, glutathione S-transferase, superoxide dismutase and catalase).
The present article reviews the historical and popular uses of garlic, its antioxidant, haematological, antimicrobial, hepatoprotective and antineoplastic properties and its potential toxicity (from sulfoxide). Garlic has been suggested to affect several cardiovascular risk factors. It has also been shown that garlic and its organic allyl sulfur components are effective inhibitors of the cancer process. Since garlic and its constituents can suppress carcinogen formation, bioactivation and tumour proliferation, it is imperative that biomarkers be established to identify which individuals might benefit most. Garlic powder, aged garlic and garlic oil have demonstrated antiplatelet and anticoagulant effects by interfering with cyclo-oxygenase-mediated thromboxane synthesis. Garlic has also been found to have synergistic effects against Helicobacter pylori with a proton pump inhibitor. The active compound allicin may affect atherosclerosis not only by acting as an antioxidant, but also by other mechanisms, such as lipoprotein modification and inhibition of LDL uptake and degradation by macrophages. Freshly prepared garlic homogenate protects against isoniazid+rifampicin-induced liver injury in experimental animal models. Several mechanisms are likely to account for this protection.
The experimental and theoretical results of the electronic and optical properties of quantum dot artificial molecules (AMs), formed by pairs of electronically coupled quantum dots (QDs), are presented here in order to identify the necessary conditions for the development of new types of terahertz (THz) injection lasers based on intraband carrier transitions. We have performed analytical calculations to obtain the spatial strain distribution in vertically aligned (In, Ga)As QDs grown on (001) GaAs substrates by molecular beam epitaxy. Electronic coupling of the dots, mainly governed by the thickness of the separating barrier between the dot layers, is allowed due to the strain field-assisted self-organization of the dots. The calculated strain field reproduces our cross sectional high-resolution transmission electron microscopy observations very well. We further take into account the microscopic effects of the spatial strain distribution on carrier confinement potentials, and compute the electronic structure of the AM. Our calculations of the peak luminescence energies are in good agreement with our experimental results and those of others. The growth of quantum dot molecules represents a major step in tailoring the electronic and optical properties of the nanostructures.
We report the fabrication and characterization of alternating current light-emitting diodes (LEDs) with quinquethiophene as the emitting material. We have obtained equal electroluminescence intensity in both bias sections. From the frequency response of the LEDs, we have estimated the device response times and compared them with the response times obtained from the transient response of dc LEDs. Langmuir-Blodgett film deposition technique has been employed to control the thickness of the emitting layer on the molecular scale. We have shown that the response times originate from the accumulation rather than the transit of charge carriers. We have compared the photo- and electroluminescence spectra of QT LEDs.
We report a study of the electrical and optical properties of thin films of tetraanilinobenzene (TAB) and polyaniline (PANI) deposited using the Langmuir-Blodgett (LB), layer-by-layer selfassembly and vacuum-evaporation techniques. The paper will mainly concentrate on TAB LB films, but also results for other films are presented for comparison. The optical studies of undoped TAB LB films indicate H-aggregates. Upon doping new polaronic absorption bands appear and the photoluminescence of TAB becomes quenched. Doped LB and self-assembled films can reach conductivities up to about 10−4/cm for TAB and a few S/cm for PANT. The conductivity has a temperature dependence logσ α T−1/2, suggesting variable-range hopping in a quasi-gap, possibly due to the Coulomb interactions between localized carriers.
Highly transparent films with tailorable sheet resistivity were prepared by ion-beam sputtering of indium tin oxide (ITO) with MgF2 or SiO2 in the presence of high-purity air. Sheet resistivities of 103−101 ohms/square (ω/–) and visible transmittances as high as 92% (not corrected for substrate absorption) were obtained in films ∼30 nm thick. Resistivity increased by as much as two orders of magnitude in the first year after preparation; however, thicker films (e.g. 80 nm) were much more stable but somewhat less transparent. Preliminary data from exposure of film samples to atomic oxygen in a plasma asher indicate minimal degradation in optical properties. Heat-treating pure ITO in air produced transparent, slightly conductive films but with poorer stability of sheet resistivity in air than co-deposited ITO with either SiO2, or MgF2. Electrical transport measurements yielded new information on the electronic properties of ITO and related materials. These films show promise as low-absorption static bleedoff coatings for space photovoltaic arrays as well as CRT faceplates and other commercial applications.
In the single-step SOFC co-firing process YSZ electrolytes with sintering aid densify at a temperature of ˜1300°C. Electrodes employed in the single-step co-fired SOFC must therefore sinter with the right microstructure at ˜1300°C. Calcium-doped lanthanum ferrite, La0.8Ca0.2FeO3±δ (LCF-20) was identified in earlier studies as a possible stable cathode material for the single-step co-fired SOFC. LCF-20 is also expected to be a more stable cathode material than LSCF (strontium and cobalt doped lanthanum ferrite).
Four-probe conductivity tests yielded ˜93 S/cm at 800°C and showed an increase in conductivity as pO2 increases, characteristic of p-type conduction. LCF has a higher electrical conductivity compared to LSCF and LCM+YSZ cathode materials. Oxygen ion conductivity of LCF-20 obtained from permeability measurements is higher than that of YSZ and LSF-20. Therefore LCF has excellent mixed conducting properties to serve as a catalytically active cathode material for co-fired solid oxide fuel cells operating at intermediate temperatures.
Electrochemical Impedance Spectroscopy (EIS) measurements were made on symmetrical cells fabricated with YSZ electrolyte and the electrode materials. A gadolium doped ceria (GDC) barrier layer was employed to prevent LCF/YSZ reaction. Comparison of LCF/GDC/YSZ/GDC/LCF EIS data to LCM+YSZ/YSZ/LCM+YSZ EIS data gathered using identical test conditions and electrode microstructures shows that LCF has a measured polarization resistance (Rp) of approximately half that seen in LCM+YSZ. Variations in cathode thickness and porosity show the best performance with a cathode of a critical thickness and finer porosity.
Slight stoichiometric deviations in LCF result in the formation of a Ca-Fe-O liquid phase during electrode sintering at around 1220 C. The liquid phase migrates into and through the GDC layer. EDX line scans show the second phase to be rich in Ca and Fe. Thicker GDC layers seem to prevent the liquid phase from reaching the electrolyte/GDC interface. Structural analysis with TEM will be performed.
The properties and the effect of the Ca-Fe-O phase on the cathodic performance of the cell are being investigated; however, preliminary results indicate that minor amounts of the Ca-Fe-O phase will not interfere with the electrochemical performance of the LCF cathode. The high temperature instability in LCF has been observed in other studies, but has not been studied specifically in the literature.
Particle size dependent transport properties (resistivity and thermopower) of La0.5Pb0.5MnO3 has been investigated both in presence and in absence of magnetic field B=0.0-1.5T (maximum). All the samples show metal-insulator transition (MIT) with a peak at the MIT temperature (Tp). Magnetic field decreases the resistivity with an increase in the peak temperature Tp. Particle size, conductivity and Tp of the sample increase with increasing annealing time. High temperature semiconducting (insulating) part of the resistivity curve is divided into two distinct regimes. Resistivity data for T>qθ/2, can be well fitted with the nearest neighbor small polaron hopping (SPH) model. Polaron hopping energy (WH) decreases with increase of particle size. The lower temperature part (Tp>T>qθ/2) of the semiconducting (insulating) regime is found to follow variable range hopping (VRH) model. With the increase of particle size, the temperature range of validity of the VRH mechanism decreases. The low temperature metallic regime (for T<Tp) of the resistivity (both in absence and in presence of field) data fit well with ρ = ρ0 +ρ2.5 T2.5 and transport mechanism in this region is mainly dominated by magnon-carrier scattering (∼T2.5). Particle size has, however, comparatively little effect on Seebeck coefficient (S). In all the samples with different particle sizes, S changes sign below Tp. In contrast to magnetoresistance, application of magnetic field increases S at low temperature (T<Tp) for these samples. Similar to the resistivity results, thermopower data in the metallic phase (both for B=0.0 and 1.5T) can also be analyzed by considering magnon-scattering term along with an additional spin-wave fluctuation term (∼T4).
Three nickel-base austenitic alloys, namely Alloy C-22, Alloy C-276 and Waspaloy have been tested for evaluation of their corrosion resistance in an acidic solution at ambient and elevated temperatures. The results of stress corrosion cracking studies indicate that none of these materials did exhibit any failure at constant load. The cracking susceptibility determined by the slow strain rate technique was gradually enhanced at higher temperatures showing reduced ductility and true failure stress. The critical potentials determined by the polarization technique, became more active (negative) with increasing temperature. The fractograpic evaluations by scanning electron microscopy (SEM) revealed ductile failure in Alloys C-22 and C-276. However, Waspaloy showed brittle failure at elevated temperature.