50175 research outputs found
Sort by
Emblica officinalis-loaded poly(epsilon-caprolactone) electrospun nanofiber scaffold as potential antibacterial and anticancer deployable patch
No full textBiological functions of nanofiber scaffolds can be engineered via the incorporation of plant extracts. In the present study, Emblica officinalis (EO) (Indian Gooseberry known as amla)-loaded poly(epsilon-caprolactone) (PCL) nanofibers were prepared via the electrospinning technique. The aim was to prepare nanofiber scaffolds with antibacterial and anti-cancerous properties. The scaffolds were characterized via SEM, XRD, small-angle X-ray scattering, FTIR spectroscopy, streaming potential, DSC, water contact angle and tensile measurements. Upon the incorporation of EO, the nanofiber surface became rougher and exhibited a braid-like' morphology. This is in contrast to the pristine PCL nanofibers, which exhibited a smooth fiber surface. The average fiber diameter increased, and the water contact angle of the nanofiber scaffolds decreased with an increase in the EO content in PCL. The crystalline structure of PCL was not affected; however, its crystallization temperature increased significantly and its melting temperature increased marginally with the addition of EO. The PCL scaffold showed a negatively charged surface and its -potential increased with an increase in EO content due to the presence of various functional groups. The antibacterial studies revealed that the PCL-EO nanofiber scaffolds exhibited efficient antibacterial properties against both Gram-positive and Gram-negative bacterial strains and the zone of inhibition increased with EO content. Furthermore, cellular behavior of MCF-7 cells was studied using the MTT assay, fluorescent staining and SEM, which indicated that cell proliferation was significantly inhibited by the incorporation of EO in the scaffolds
Massive scattering amplitudes in six dimensions
No full textWe show that a natural spinor-helicity formalism that can describe massive scattering amplitudes exists in D = 6 dimensions. This is arranged by having helicity spinors carry an index in the Dirac spinor 4 of the massive little group, SO(5) � Sp(4). In the high energy limit, two separate kinds of massless helicity spinors emerge as required for consistency with arXiv:0902.0981, with indices in the two SU(2)�s of the massless little group SO(4). The tensors of 4 lead to particles with arbitrary spin, and using these and demanding consistent factorization, we can fix 3� and 4-point tree amplitudes of arbitrary masses and spins: we provide examples. We discuss the high energy limit of scattering amplitudes and the Higgs mechanism in this language, and make some preliminary observations about massive BCFW recursion. © 2019, The Author(s)
Invariants of the Z(2) orbifolds of the Podles two spheres
No full textThere are two Z(2) orbifolds of the Podles quantum two-sphere, one being the quantum two-disc D-q and other the quantum two-dimensional real projective space RPq2. In this article we calculate the Hochschild and cyclic homology and cohomology groups of these orbifolds and also the corresponding Chern-Connes indices
Two-Point Grasp Response
No full textThis paper for the first time in literature studies the quasi-static behavior of a smooth object when it is being grasped with two rigid point fingers without friction and in the absence of external forces. A simple model of slip for the point finger over the object is proposed and the evolution of the traces of the point of contact of the fingers are computationally determined. The kinematic response of the object as viewed from one finger is assessed with the evolution of the slip. The convergence of the two slip-loci to two distinct points or a single point imply a successful or failed grasp endeavor, respectively. It is argued that the slip-loci are geodesics on the smooth object which gets temporally parametrized, as slip evolves
Hot deformation behavior of the high-entropy alloy CoCuFeMnNi
No full textIn the present study, hot deformation behavior of a FCC high-entropy alloy CoCuFeMnNi has been investigated to explore the stress-strain response for a wide range of temperatures and strain rates. The deformation response has been examined by plotting a processing map and examining the evolution of microstructure and texture in each of the temperature-strain rate domain. Hot compression tests were carried out in the temperature range 850-1050 degrees C at strain rates varying from 0.001 s(-1) to 10 s(-1). Stress-strain curves indicate characteristic softening behavior due to dynamic recrystallization (DRX). DRX has been observed along grain boundaries, shear bands, as well as in the interior of deformed grains. The size of dynamically recrystallized grains shows a strong dependence on deformation temperature and increases with temperature. A high degree of twin formation takes place in the DRX grains evolved inside the shear bands, and the extent of twinning decreases at high temperatures. The optimal processing window has been estimated based on strain rate sensitivity and has been validated with detailed analyses of microstructure and texture. The best region for thermo-mechanical processing has been identified as in the temperature range 850-950 degrees C at strain rate 10(-1) s-1
NapA (Rv0430), a Novel Nucleoid-Associated Protein that Regulates a Virulence Operon in Mycobacterium tuberculosis in a Supercoiling-Dependent Manner
No full textComparison of Mycobacterium tuberculosis with Escherichia coli reveals a reduction in the diversity of DNA-managing proteins, such as DNA topoisomerases, although genome sizes are similar for the two species. The same is true for nucleoid-associated proteins (NAPs), important factors in bacterial chromosome compaction, chromosome remodeling, and regulation of gene expression. In a search for still uncharacterized NAPs, we found that M. tuberculosis protein Rv0430 has NAP-like features: it binds to DNA in a length-and supercoil-dependent fashion, prefers AfT-rich DNA sequences, protects DNA from damaging agents, and modulates DNA supercoiling. At a ratio of 1 dimer/40 bps of DNA, Rv0430 bridges distant DNA segments; at 1 dimer/20 bps, it coats DNA, forming inflexible rods. Rv0430 also stimulates the DNA relaxation activity of topoisomerase I. Remarkably, Rv0430 stimulates its own promoter in a supercoil-dependent manner. It is the first gene of an operon harboring two regulators of M. tuberculosis virulence (virR and sodC), and controls the expression of these downstream virulence regulators and therefore itself is a virulence regulator. The sensitivity of rv0430 expression to supercoiling is consistent with supercoiling being important for infection by M. tuberculosis. Thus, Rv0430 is a novel NAP, doubling up as a topology modulator of M. tuberculosis. (C) 2019 Elsevier Ltd. All rights reserved
Handheld, low-cost electronic device for rapid, real-time fluorescence-based detection of Hg2+, using aptamer-templated ZnO quantum dots
No full textMercury is one of the most acute toxic heavy metals at trace levels and its detection at parts per billion (ppb) scale in a low-cost, simple way remains challenging. Here, we report a novel ``Turn-On'' fluorescence sensor based on aptamer-templated ZnO quantum dots (QDs), which was further developed into an electronic detection device and utilized for the rapid detection of mercury ions (Hg2+). Binding of Hg2+ with the aptamer leads to the formation of a duplex, T-Hg2+-T, and this acts as a template for the formation of ZnO QDs. With an increase in the concentration of Hg2+, we observed an increase in duplex formation, leading to enhancement in the fluorescence. The limit of detection of the device is 0.1 ppb (0.5 nM), and experimental analysis has a linear range of detection between 0.1 and 10,000 ppb. Electron microscopy studies ascertained the crystalline nature of the aptamer-templated ZnO QDs in the presence of Hg2+. Finally, the sensing was implemented as a simple working electronic detection device prototype. A photodiode coupled with an LED source was connected to an Arduino Nanoboard for the development of the device. To the best of our knowledge, this is the first study to report an enhancement in the fluorescence of the aptamer-templated ZnO QDs with an increase in the concentration of Hg2+. Moreover, this is the first report of an analyte addition during the synthesis of QDs, leading to fluorescence-based sensing of the added analyte. Thus, a novel fluorescence sensor based on aptamer-templated ZnO QDs has been demonstrated with high sensitivity and selectivity, resulting in a simple electronic detection device
Creep of Cu-Bi Alloys with High Bi Content Near and Above Melting Temperature of Bi
No full textCu-Bi alloy with high Bi content can be used for thermal surge protection and energy storage. For these applications, creep at high temperatures, including temperatures above the melting temperature of Bi, T-m,T-Bi, becomes important. Accordingly, the creep behavior of Cu-Bi alloys, comprising 30 and 40 vol pct Bi, was studied under compression at temperatures above and below T-m,T-Bi. At 200 degrees C, which is below T-m,T-Bi, Cu-Bi showed a stress exponent of similar to 4 at high stresses and similar to 1 at low stresses. Finite element analysis revealed that the creep behavior of Cu-Bi at 200 degrees C was predominantly governed by Bi. On the other hand, at temperatures higher than T-m,T-Bi, Cu-Bi showed a short transient stage at high stresses, followed by sudden failure of the material. However, at low stresses, the sample first continued to expand and then started to accumulate compressive strain. A qualitative model based on interaction between liquid Bi and Cu is developed to explain the observed creep behavior at temperatures higher than T-m,T-Bi. The results obtained here shed light on the creep behavior of alloys with constituents having significantly different creep behavior and containing a non-reacting liquid phase. (C) The Minerals, Metals & Materials Society and ASM International 201
Shower effect of a rainfall onset on the heat accumulated during a preceding dry spell
No full textPopular perception claims that rain following a hot day brings relief, indicating a bio-meteorological perspective of `rainy' forecasts. However, the hypothesis has rarely been examined on India which experiences distinct pre-and post-monsoon seasons with continuous dry days, occasionally interrupted by thunderstorms or cyclones. The current study analyzes 54 years of observed daily meteorological records across India to assess the impact of shower effect, defined as the amount of change in the temperature on the first day of a wet spell that succeeds a dry spell. Nine combinations of low to high probability rainfall events on the first day of a wet spell and short to prolonged dry spell categories are evaluated. Results indicate that the north, the northeastern, and the eastern states of India witness a decrease in the maximum and minimum temperatures, up to 5 degrees C during the pre-monsoon season while mostly exhibiting a statistically insignificant long-term temporal trend. During the post-monsoon season, a rainfall event decreases the maximum temperature, providing significant relief by reducing the heat index (HI) warning from `Caution' to `Normal', but is unable to lower the HI warning from `danger' during the pre-monsoon season