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A smart nanosensor for the detection of human immunodeficiency virus and associated cardiovascular and arthritis diseases using functionalized graphene-based transistors
No full textHuman immunodeficiency virus (HIV), which isa worldwide public health issue, is commonly associated with cardiovascular disorders (CVDs) and rheumatoid arthritis (RA). A smart nanosensor was developed for the detection of HIV and its related diseases (CVDs and RA) using graphene-based field-effect transistors (FETs). In this study, amine-functionalized graphene (afG) was conjugated with antibodies anti-p24 for HIV, anti-cardiac troponin 1 (anti-cTn1) for CVDs, and anti-cyclic citrullinated peptide (anti-CCP) for RA] to detect various biomarkers. The antibodies were covalently conjugated to afG via carbodiimide activation. The bioconjugate (graphene-antibody) was characterized by various biophysical techniques such as UV-Vis, Raman spectroscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM). The electrochemical performance of the sensor was evaluated with respect to changes in the resistance of the electrode surface due to the interaction of the antigen with its specific antibody. The developed sensor was highly sensitive and showed a linear response to p24, cTn1, and, CCP from 1 fg/mL to 1 mu g/mL. The limit of detection (LOD) was 100 fg/mL for p24 and 10 fg/mL for cTn1 and CCP under standard optimized conditions. The graphene-based smart nanodevice demonstrated excellent performance; thus, it could be used for the on-site detection of HIV, CVD, and RA biomarkers in real samples
Photocytotoxic copper(II) complexes of N-salicylyl-L-tryptophan and phenanthroline bases
No full textFour ternary copper(II) complexes of N-salicylyl-L-Tryptophan (Sal-TrpH) and phenanthroline bases of general formula Cu(Sal-Trp)(L)], where L is 1,10-phenanthroline (phen, 1), dipyrido3,2-d:2',3'-f]quinoxaline (dpq, 2), dipyrido 3,2-a:2',3'-c] phenazine (dppz, 3) and 2-(anthracen-1-yl)-1H-imidazo 4,5-f] 1,10] phenanthroline (aip, 4), were synthesized and fully characterized. The complexes were evaluated for their affinity for biomolecules and photocytotoxic activities. Single crystal X-ray diffraction studies of complex 1 revealed that it has a square pyramidal CuN3O2 core with the phenolate oxygen of salicylaldehyde occupying the axial coordination site in the solid state. Complexes 1-4 displayed the Cu(II)-Cu(I) redox couples at similar to - 0.3 V vs. Ag/AgCl reference electrode in DMF-0.1 M (Bu4N)-N-n](ClO4). A Cu(II)-based weak d-d band similar to 650 nm and a moderately strong ligand to metal charge transfer band at similar to 430 nm were observed in DMF-Tris-HCl buffer (pH 7.2) (1:4 v/v). The complexes are efficient binders to calf thymus DNA and model proteins such as bovine serum albumin and lysozyme. They cleave supercoiled plasmid DNA efficiently when exposed to 446 and 660 nm laser radiation. They are cytotoxic to HeLa (human cervical cancer) and MCF-7 (human breast cancer) cells showing significant enhancement of cytotoxicity upon photo-excitation with low energy visible light. The complexes are found to kill cancer cells through generation of reactive oxygen species (ROS) as confirmed by DCFDA (2',7'-dichlorofluorescin diacetate) assay. The apoptotic cell death induced by complex 4 was confirmed by Annexin V-Fluorescein isothiocyanate-Propidium iodide assay. Confocal microscopic images using 4 showed its primary cytosolic localization in the HeLa and MCF-7 cells
Living orthogonally: quasi-universal extra dimensions
No full textThe minimal Universal Extra Dimension scenario is highly constrained owing to opposing constraints from the observed relic density on the one hand, and the non-observation of new states at the LHC on the other. Simple extensions in five-dimensions can only postpone the inevitable. Here, we propose a six-dimensional alternative with the key feature being that the SM quarks and leptons are localized on orthogonal directions whereas gauge bosons traverse the entire bulk. Several different realizations of electroweak symmetry breaking are possible, while maintaining agreement with low energy observables. This model is not only consistent with all the current constraints opposing the minimal Universal Extra Dimension scenario but also allows for a multi-TeV dark matter particle without the need for any fine-tuning. In addition, it promises a plethora of new signatures at the LHC and other future experiments
Electrical transport and gas sensing characteristics of dielectrophoretically aligned MBE grown catalyst free InAs nanowires
No full textIn this report, the precise alignment of catalyst free InAs nanowires (NWs) on pre-patterned Au microelectrodes by dielectrophoresis (DEP) technique for gas sensing applications is presented. The catalyst free InAs NWs have been grown on Si (111) substrate by molecular beam epitaxy (MBE) technique. The effect of dispersing solvents, electrode geometries and gaps, magnitude, frequency and duration of applied voltage etc, has been studied for aligning the InAs NWs by DEP technique. Current-voltage (I-V) measurements on the aligned NWs show linear behavior at room temperature (300 K), which changes to nonlinear at lower temperatures and higher voltages. The nonlinearity at lower temperatures and higher voltages is well explained by a space charge limited current contribution, which further gives a quantitative estimation of free charge carriers and trap density. The DEP aligned NWs exhibit good sensing response upon exposure to 10 ppm NO2 gas
Highly Electroactive Ni Pyrophosphate/Pt Catalyst toward Hydrogen Evolution Reaction
No full textRobust electrocatalysts toward the resourceful and sustainable generation of hydrogen by splitting of water via electrocatalytic hydrogen evolution reaction (HER) are a prerequisite to realize high-efficiency energy research. Highly electroactive catalysts for hydrogen production with ultralow loading of platinum (Pt) have been under exhaustive exploration to make them cutting-edge and cost-effectively reasonable for water splitting. Herein, we report the synthesis of hierarchically structured nickel pyrophosphate (beta-Ni2P2O7) by a precipitation method and nickel phosphate (Ni-3(PO4)(2)) by two different synthetic routes, namely, simple cost-effective precipitation and solution combustion processes. Thereafter, Pt-decorated nickel pyrophosphate and nickel phosphate (beta-Ni2P2O7/Pt and Ni-3(PO4)(2)/Pt) were prepared by using potassium hexachloroplatinate and ascorbic acid. The fabricated novel nickel pyrophosphate and nickel phosphate/Pt materials were utilized as potential and affordable electrocatalysts for HER by water splitting. The detailed electrochemical studies revealed that the beta-Ni2P2O7/Pt (1 mu g.cm(-2) Pt) electrocatalyst showed excellent electrocatalytic performances for HER in acidic solution with an overpotential of 28 mV at -10 mA.cm(-2), a Tafel slope of 32 mV.dec, and an exchange current density (j(0)) of -1.31 mA.cm(-2), which were close to the values obtained using the Vulcan/Pt (8.0 mu g.cm(-2) Pt), commercial benchmarking electrocatalyst with eight times higher Pt amount. Furthermore, the beta-Ni2P2O7/Pt electrocatalyst maintains an excellent stability for over -0.1 V versus RHE for 12 days, keeping j(0) equal after the stability test (-1.28 mA cm(-2)). Very well-distributed Pt NPs inside the cages on the beta-Ni2P2O7 structure with a crystalline pattern of 0.67 nm distance to the Ni2P2O7/Pt electrocatalyst, helping the Volmer-Tafel mechanism with the Tafel reaction as a major rate-limiting step, help to liberate very fast the Pt sites after HER. The high electrocatalytic performance and remarkable durability showed the beta-Ni2P2O7/Pt material to be a promising cost-effective electrocatalyst for hydrogen production
The Phase Diagram for a Multispecies Left-Permeable Asymmetric Exclusion Process
No full textWe study a multispecies generalization of a left-permeable asymmetric exclusion process (LPASEP) in one dimension with open boundaries. We determine all phases in the phase diagram using an exact projection to the LPASEP solved by us in a previous work. In most phases, we observe the phenomenon of dynamical expulsion of one or more species. We explain the density profiles in each phase using interacting shocks. This explanation is corroborated by simulations
Correlation between anodization variables and surface properties of titania nanotube arrays for dye-sensitized solar cells
No full textThe effect of anodization variables on the morphology and surface properties of oriented titania nanotube arrays (TNAs) was investigated. The arrays were synthesized using hydrofluoric acid based ethylene glycolelectrolyte. The results show that the anodization time plays a significant role in the surface properties as well as length of the nanotubes. However, the contribution of anodization potential to debris formation was found to be negligible within the investigated range of the potential. The F- ion concentration and aging of electrolyte were found to play crucial roles in the formation of ordered clean nanotubes. The studies conducted by employing these TNAs as photo-anodes for dye-sensitized solar cells (DSCs) show that the morphology variations alone alter the photovoltaic properties of DSCs to a great extent
The large protein ``L' of Peste-des-petits-ruminants virus exhibits RNA triphosphatase activity, the first enzyme in mRNA capping pathway
No full textPeste-des-petits-ruminants is a highly contagious and fatal disease of goats and sheep caused by non-segmented, negative strand RNA virus belonging to the Morbillivirus genusPeste-des-petits-ruminants virus (PPRV) which is evolutionarily closely related to Rinderpest virus (RPV). The large protein L' of the members of this genus is a multifunctional catalytic protein, which transcribes and replicates the viral genomic RNA as well as possesses mRNA capping, methylation and polyadenylation activities; however, the detailed mechanism of mRNA capping by PPRV L protein has not been studied. We have found earlier that the L protein of RPV has RNA triphosphatase (RTPase), guanylyltransferase (GTase) and methyltransferase activities, and unlike vesicular stomatitis virus (VSV), follows the conventional pathway of mRNA capping. In the present work, using a 5-end labelled viral RNA as substrate, we demonstrate that PPRV L protein has RTPase activity when present in the ribonucleoprotein complex of purified virus as well as recombinant L-P complex expressed in insect cells. Further, a minimal domain in the C-terminal region (aa1640-1840) of the L protein has been expressed in E. coli and shown to exhibit RTPase activity. The RTPase activity of PPRV L protein is metal-dependent and functions with a divalent cation, either magnesium or manganese. In addition, RTPase associated nucleotide triphosphatase activity (NTPase) of PPRV L protein is also demonstrated. This work provides the first detailed study of RTPase activity and identifies the RTPase domain of PPRV L protein
Diffusional and electrochemical investigation of combustion synthesized BaLi2Ti6O14 titanate anode for rechargeable batteries
No full textEnergy-savvy auto-combustion synthesis was used to form the porous BaLi2Ti6O14 titanate anode. It registered the lowest calcination temperature (800 degrees C) along with the shortest calcination duration (2 h). Rietveld analysis confirmed the purity of the orthorhombic (s. g. Cmca) product phase. The bond valence site energy analysis indicated a 1D ionic conduction along c axis with low activation energy and 2D pathways along (010) with high activation energy. AC conductivity analysis revealed a bulk conductivity of 2.41 x 10(-4) S/cm (at 300 degrees C) with a moderate activation energy barrier (0.68 eV). From cyclic voltammetry, the Li+ diffusion coefficient was calculated to be 10(-11)-10(-12) cm(2)/s. The as-synthesized BaLi2Ti6O14 reversibly intercalated; similar to 1.3 Li+ involving a 1.42 V Ti4+/Ti3+ redox activity delivering capacity; similar to 100 mA h/g with good cyclability over 100 cycles. Furthermore, BaLi2Ti6O14 was found to reversibly intercalate similar to 0.89 Na+. With suitable diffusional and electrochemical performance, BaLi2Ti6O14 form a safe titanate anode for secondary batteries
