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An efficient and cost-effective method for purification of small sized DNAs and RNAs from human urine
No full textUrine holds great promise as a non-invasive sampling method for molecular diagnostics. The cell-free nucleic acids of urine however are small, labile, and difficult to purify. Here an efficient method for the purification of these nucleic acids is presented. An empirically derived protocol was devised by first identifying conditions that allowed recovery of a 100 base pair (bp) DNA, followed by optimization using a quantitative polymerase chain reaction (qPCR) assay. The resulting method efficiently purifies both small sized DNAs and RNAs from urine, which when combined with quantitative reverse transcription PCR (qRTPCR), demonstrably improves detection sensitivity. Fractionation experiments reveal that nucleic acids in urine exist both in the cell-free and cellular fraction, roughly in equal proportion. Consistent with previous studies, amplicons > 180bp show a marked loss in PCR sensitivity for cell-free nucleic acids. Finally, the lysis buffer developed here also doubles as an effective preservative, protecting against nucleic acid degradation for at least two weeks under simulated field conditions. With this method, volumes of up to 25ml of whole urine can be purified in a high-throughput and cost-effective manner. Coupled with its ability to purify both DNA and RNA, the described method may have broad applicability for improving the diagnostic utility of urine, particularly for the detection of low abundant targets
Constraining the mass of the black hole GX 339-4 using spectro-temporal analysis of multiple outbursts
No full textWe carried out spectro-temporal analysis of the archived data from multiple outbursts spanning over the last two decades from the black hole X-ray binary GX 339-4. In this paper, the mass of the compact object in the X-ray binary system GX 339-4 is constrained based on three indirect methods. The first method uses broadband spectral modelling with a two component flow structure of the accretion around the black hole. The broadband data are obtained from RXTE (Rossi X-ray Timing Explorer) in the range 3.0 to 150.0 keV and from Swift and NuSTAR (Nuclear Spectroscopic Telescope Array) simultaneously in the range 0.5 to 79.0 keV. In the second method, we model the time evolution of Quasi-periodic Oscillation (QPO) frequencies, considering it to be the result of an oscillating shock that radially propagates towards or away from the compact object. The third method is based on scaling a mass dependent parameter from an empirical model of the photon index (Gamma) - QPO (v) correlation. We compare the results at 90 percent confidence from the three methods and summarize the mass estimate of the central object to be in the range 8.28-11.89M(circle dot). (C) 2018 COSPAR. Published by Elsevier Ltd. All rights reserved
Mechanistic Insight into the Nature of Dopants in Graphene Derivatives Influencing Electromagnetic Interference Shielding Properties in Hybrid Polymer Nanocomposites
No full textThe recent surge in the usage of electronics has led to a new kind of problem; electromagnetic interference which necessitates finding alternate materials that offer ease of processing, design flexibility, light weight, and ease of embedding and integrating with the existing systems in place as shields to protect the precise electronic circuitry. Herein, lightweight polycarbonate (PC)-based nanocomposites using doped graphene derivatives and multiwalled carbon nanotubes (MWCNT) has been explored for effective shielding of EM radiation in X- and Ku-band. To get a mechanistic insight as to how the dopant in graphene derivatives influences the EM shielding properties, two dopants have been explored here: ferrimagnetic (ferrite, Fe3O4) and the other one as paramagnetic (gadolinium oxide, Gd2O3). The doped graphene derivatives when composited with PC and MWCNTs resulted in materials that can shield the incoming EM radiation through magnetic and dielectric losses. This strategy of doping improves the state of dispersion of these dopants in the nanocomposites, besides enhancing the shielding effectiveness. The PC-based nanocomposites illustrated a total shielding effectiveness (SET) of -28 and -33 dB at 18 GHz for a given concentration of Gd2O3 and Fe3O4 hybrid, respectively. A closer look into the mechanism of shielding reveals that irrespective of the dopant, various losses (magnetic and dielectric) decide the shielding effectiveness in polymeric nanocomposites facilitated by multiple internal reflections. Taken together, this study brings in new insight as to how the losses contribute toward effective shielding rather than the choice of the dopant and will help guide researchers working in this area from both industrial as well as academic perspective
Long-range molecular dynamics show that inactive forms of Protein Kinase A are more dynamic than active forms
No full textMany protein kinases are characterized by at least two structural forms corresponding to the highest level of activity (active) and low or no activity, (inactive). Further, protein dynamics is an important consideration in understanding the molecular and mechanistic basis of enzyme function. In this work, we use protein kinase A (PKA) as the model system and perform microsecond range molecular dynamics (MD) simulations on six variants which differ from one another in terms of active and inactive form, with or without bound ligands, C-terminal tail and phosphorylation at the activation loop. We find that the root mean square fluctuations in the MD simulations are generally higher for the inactive forms than the active forms. This difference is statistically significant. The higher dynamics of inactive states has significant contributions from ATP binding loop, catalytic loop, and alpha G helix. Simulations with and without C-terminal tail show this differential dynamics as well, with lower dynamics both in the active and inactive forms if C-terminal tail is present. Similarly, the dynamics associated with the inactive form is higher irrespective of the phosphorylation status of Thr 197. A relatively stable stature of active kinases may be better suited for binding of substrates and detachment of the product. Also, phosphoryl group transfer from ATP to the phosphosite on the substrate requires precise transient coordination of chemical entities from three different molecules, which may be facilitated by the higher stability of the active state
Histogram of oriented gradients: a technique for the study of molecular cloud formation
No full textWe introduce the histogram of oriented gradients (HOG), a tool developed for machine vision that we propose as a new metric for the systematic characterization of spectral line observations of atomic and molecular gas and the study of molecular cloud formation models. In essence, the HOG technique takes as input extended spectral-line observations from two tracers and provides an estimate of their spatial correlation across velocity channels. We characterized HOG using synthetic observations of HI and (CO)-C-13(J = 1 -> 0) emission from numerical simulations of magnetohydrodynamic (MHD) turbulence leading to the formation of molecular gas after the collision of two atomic clouds. We found a significant spatial correlation between the two tracers in velocity channels where v(HI) approximate to v(13CO), almost independent of the orientation of the collision with respect to the line of sight. Subsequently, we used HOG to investigate the spatial correlation of the HI, from The HI/OH/recombination line survey of the inner Milky Way (THOR), and the (CO)-C-13(J = 1 -> 0) emission from the Galactic Ring Survey (GRS), toward the portion of the Galactic plane 33.degrees 75 <= l <= 35.degrees 25 and vertical bar b vertical bar <= 1.degrees 25. We found a significant spatial correlation between the two tracers in extended portions of the studied region. Although some of the regions with high spatial correlation are associated with HI self-absorption (HISA) features, suggesting that it is produced by the cold atomic gas, the correlation is not exclusive to this kind of region. The HOG results derived for the observational data indicate significant differences between individual regions: some show spatial correlation in channels around v(HI) approximate to v(13CO) while others present spatial correlations in velocity channels separated by a few kilometers per second. We associate these velocity offsets to the effect of feedback and to the presence of physical conditions that are not included in the atomic-cloud-collision simulations, such as more general magnetic field configurations, shear, and global gas infall
Performance Analysis and Fault Diagnosis Method for Concentrator Photovoltaic Modules
No full textConcentrator photovoltaic (CPV) systems use high efficiency multi-junction solar cells with efficiencies >40%, but the module efficiency is often much lower. The increased complexity of a CPV module, with optics, receiver, and the tracker give an increased probability that faults will arise during the operational lifetime. In addition, a location like India has varied atmospheric conditions that further complicate the diagnosis of faults. It is therefore important to decouple effects due to the external environment (such as the atmosphere) from effects due to the degradation of the module. By applying a computer model to outdoor CPV test data in Bangalore, India, we have established a method to assess the performance of the CPV module and finally we present a method to diagnose faults in the module
Theoretical and numerical analysis of stepped disk spring
No full textDisk springs have been widely used in machine tools, aerospace vehicles, and automobiles. Pioneering work by Almen -Laszlo has inspired a deeper understanding of the nonlinear behavior over the last eight decades. There is a need for extending the analysis for stepped section disk springs. In this paper, we report the effect of the stepped section on the force-deflection and variable stiffness characteristics. A simplified method for predicting load deflection of the stepped disk spring has been developed incorporating the geometric non-linearity. Extending the work of Almen-Laszlo, Curti, and Rosa, we present a theoretical analysis that predicts the force deflection characteristic as function of the geometric parameter and the theoretical model is verified using finite element results
HIV-1 vaccination by needle-free oral injection induces strong mucosal immunity and protects against SHIV challenge
No full textThe oral mucosa is an attractive site for mucosal vaccination, however the thick squamous epithelium limits antigen uptake. Here we utilize a modified needle-free injector to deliver immunizations to the sublingual and buccal (SL/B) tissue of rhesus macaques. Needle-free SL/B vaccination with modified vaccinia Ankara (MVA) and a recombinant trimeric gp120 protein generates strong vaccine-specific IgG responses in serum as well as vaginal, rectal and salivary secretions. Vaccine-induced IgG responses show a remarkable breadth against gp70-V1V2 sequences from multiple clades of HIV-1. In contrast, topical SL/B immunizations generates minimal IgG responses. Following six intrarectal pathogenic SHIV-SF162P3 challenges, needle-free but not topical immunization results in a significant delay of acquisition of infection. Delay of infection correlates with non-neutralizing antibody effector function, Env-specific CD4(+) T-cell responses, and gp120 V2 loop specific antibodies. These results demonstrate needle-free MVA/gp120 oral vaccination as a practical and effective route to induce protective immunity against HIV-1
Influence of Tool Traverse Speed on Structure, Mechanical Properties, Fracture Behavior, and Weld Corrosion of Friction Stir Welded Joints of Aluminum and Stainless Steel
No full textHerein, the effect of traverse speed on friction stir welding (FSW) of aluminum (Al) and stainless steel (SS 304) plates is studied. The microstructure of the joint sample is examined using optical microscope and scanning electron microscope equipped with energy dispersive spectroscopy. The intermetallic compound detected at the interface of friction stir welded (FSWed) joint is Al3Fe. X-ray diffraction results reveal the formation of intermetallic compound like Al3Fe, Al5Fe2, AlFe, and Al13Fe4. Tensile results show that with the increase in tool traverse speed, the tensile strength increases to reach a maximum value and then decreases. The maximum tensile strength achieved is approximate to 75% of Al base metal at tool traverse speed of 75 mm min(-1). Maximum hardness is observed at the Al|SS-304 interfaces due to the presence of intermetallics. Interfacial hardness for slower tool traverse speed is higher when compared to higher traverse speed. The electrochemical behavior of the FSWed joint is measured using potentiodynamic polarization test so as to understand the corrosion failures of the FSWed joints. FSWed samples at higher traverse speed shows inferior corrosion resistance when compared to the slower traverse speed
Initial Studies on Development of High-Performance Nano-structured Fe2O3 Catalysts for Solid Rocket Propellants
No full textSpace launch vehicles and strategic military vehicles commonly employ composite solid rocket propellants containing Fe2O3 as ballistic modifier. Nanoscale catalysts, including nanoscale Fe2O3, have been reported to exhibit superior activity in the thermal decomposition and combustion of composite rocket propellants. However, scalable methods to prepare such nano-structured catalysts with high performance as ballistic modifiers and systematic studies relating the synthesis parameters to the catalyst characteristics and consequently to the thermal and combustion properties of the composite propellant are scarce. In this paper, we report a novel and facile route to prepare nano-structured Fe2O3 with enhanced catalytic activity in the ballistic modification of ammonium perchlorate (AP)-based composite solid rocket propellant. A submerged spray precipitation method using air-assisted liquid-centered coaxial atomization has been developed to prepare these nano-structured Fe2O3 catalysts. The prepared Fe2O3 catalysts possess higher surface area and exhibit superior activity in the thermal sensitization of AP, leading to an 88% increase in the burning rate of AP-based composite solid rocket propellants, than the Fe2O3 catalyst prepared via traditional precipitation method. Merits of the developed preparatory route, influence of the atomization process on the nano-structure morphology and subsequent benefits of these nano-structured catalysts on the ballistic properties of AP-based propellants are demonstrated and discussed in this paper