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Highly Stable White-Light-Emitting Carbon Dot Synthesis Using a Non-coordinating Solvent
No full textIn this article, synthesis of white-light-emitting, highly stable carbon dots (CDs) using a colloidal synthesis technique is reported. It has been observed that the use of a non-coordinating solvent plays a vital role in the successful fabrication of highly stable CDs. Dilution-independent emissive behavior in CDs is achieved. Excitation-energy-dependent emissive behavior is observed in CDs. However, by surface passivating the CD core by using hexadecylamine (HDA), excitation wavelength dependence of emission is successfully minimized. Surface-functionalized CDs (SFCDs) show blue to green light tunable emission with the change in synthesis conditions. HDA also plays an important role in achieving dilution-independent emission in SFCDs. Furthermore, the carbon dots synthesized are highly inert, and their emission spectra are unaffected on exposure to an open atmosphere for as long as 9 days. A new class of highly crystalline carbon dots called ``carbon onion rings'' is reported
Shockwave Therapy Efficiently Cures Multispecies Chronic Periodontitis in a Humanized Rat Model
No full textBiofilms are ubiquitous in nature and are invariably associated with health and diseases of all living beings. Periodontal diseases & dental caries are the most prevalent conditions in which biofilm has established as a primary causative factor. Managing poly-microbial biofilm is the mainstay of periodontal therapy. Plethora of antimicrobials have been used till date to combat biofilm, but the emergence of antibiotic tolerance and resistance in biofilms is a major cause of concern. Apart from use of antimicrobials, various anti-biofilm strategies have evolved which include the use of mechanical, and chemical means to disrupt biofilms. However, none of these approaches have led to desired or optimal biofilm control and hence search for novel approach continues. Shockwaves are used in medical practice for various therapeutic purposes and in local drug delivery, gene therapy, wound healing & regeneration. With this background, a study was designed with an attempt to explore the possibility of using the shockwave for their effect on multispecies oral biofilm development from subgingival plaque samples obtained from chronic periodontitis patients. Plaque samples from 25 patients were used to derive multispecies biofilm which were used to check the efficacy of shockwaves and antibacterial efficacy of four clinically relevant antimicrobials. Biofilms were analyzed by scanning electron microscope; atomic force microscope and their biomass was quantitated by crystal violet staining. Further, a humanized rat model of periodontitis was developed. Patient derived plaque was used to establish periodontitis in healthy rats. The model was validated by performing colony forming unit (CFU) analysis of the infected tissue. The animals were subjected to low intensity shockwaves using a hand-held shockwave generator at the site of infection. Shockwave treatment was done with or without antimicrobial application. The animals were monitored for clearance of infection and for mortality. The results show that shockwave treatment in combination with antimicrobials is significantly effective in clearing a multispecies biofilm. This also brings out the possibility of application of shockwaves in the management of oral biofilms either alone or in combination with established antimicrobial agents. With further research, safety profile validation and clinical trials, shockwaves can be an effective, novel approach in management of biofilm associated periodontal disease
Anomalous viscoelastic response of water-dimethyl sulfoxide solution and a molecular explanation of non-monotonic composition dependence of viscosity
No full textAmphiphilic molecules such as dimethyl sulfoxide (DMSO) and its aqueous binary mixtures exhibit pronounced nonideality in composition dependence of several static and dynamic properties. We carry out detailed molecular dynamics simulations to calculate various properties including viscosity of the mixture and combine the results with a mode coupling theory analysis to show that this nonideality can be attributed to local structures that are stable on a short time scale but transient on a long time scale to maintain the large scale homogeneity of the solution. Although the existence of such quasistable structures has been deciphered from spectroscopy, a detailed characterization does not exist. We calculate stress-stress autocorrelation functions (SACFs) of water-DMSO binary mixtures. We employ two different models of water, SPC/E and TIP4P/2005, to check the consistency of our results. Viscosity shows a pronounced nonmonotonic composition dependence. The calculated values are in good agreement with the experimental results. Fourier transform of SACF provides frequency-dependent viscosity. The frequency-dependent viscosity (that is, viscoelasticity) is also found to be strongly dependent on composition. Viscoelasticity exhibits sharp peaks due to intramolecular vibrational modes of DMSO, which are also seen in the density of states. We evaluate the wavenumber dependent dynamic structure factor and wavenumber dependent relaxation time. The latter also exhibits a sharp nonmonotonic composition dependence. The calculated dynamic structure factor is used in mode coupling theory expression of viscosity to obtain a semiquantitative understanding of anomalous composition dependence of viscosity. Both the self-diffusion coefficients and rotational correlation times of water and DMSO molecules exhibit nonmonotonic composition dependence
Litter Quality Affects Termite Sheeting Production and Water Infiltration in the Soil
No full textThis study aimed to understand the relationship between termite foraging activity and the ecological benefits derived from their activity in soil dynamics and water infiltration. A field study was carried out for six months, between pre-wet and wet seasons, with different food baits (elephant dung, Acacia auriculiformis leaves, twigs and leaves of Lantana camara as well as Ficus religiosa, Pterocarpus marsupium, Prosopis juliflora, Michelia champaca, Azadirachta indica and Hevea brasiliensis wood stakes) installed on the soil surface in a semi-deciduous forest in southern India. At the end of the experiment we determined bait consumption, water infiltration rate in soil, and the amount of soil sheetings covering the different baits. The initial infiltration rates under the baits were compared to those at the end of the experiment. Three termite species, Odontotermes obesus, O. feae and Microtermes obesi, were found associated with some of the baits in the study area. Among the different baits, elephant dung and Acacia leaves were the most preferred and a positive relationship was observed between the quantity of soil sheetings and the bait consumption rate. Termite preference for elephant dung and Acacia leaves was also associated with higher water infiltration rates. However, this difference was only significant at the beginning of the experiment and no significant difference was measured once the steady state was reached. In conclusion, we showed that resource quality was of primary importance for soil sheeting production but that the influence of termites on water infiltration remained limited, most likely because of the low stability of their tunnels in the soil
VON NEUMANN'S INEQUALITY FOR COMMUTING OPERATOR-VALUED MULTISHIFTS
No full textRecently, Hartz proved that every commuting contractive classical multishift with non-zero weights satisfies the matrix-version of von Neumann's inequality. We show that this result does not extend to the class of commuting operator-valued multishifts with invertible operator weights. In fact, we show that if A and B are commuting contractive d-tuples of operators such that B satisfies the matrix-version of von Neumann's inequality and (1,..., 1) is in the algebraic spectrum of B, then the tensor product A circle times B satisfies von Neumann's inequality if and only if A satisfies von Neumann's inequality. We also exhibit several families of operator-valued multishifts for which von Neumann's inequality always holds
A one-dimensional hydrodynamic model for accretion, cooling, and heating of gas in dark matter haloes from z=6 to z=0
No full textWe study an idealized one-dimensional model for the evolution of hot gas in darkmatter haloes for redshifts z = 0, 6]. We introduce a numerical set-up incorporating cosmological accretion of gas, along with the growth of the halo, based on the Van den Bosch model for the average growth of haloes as a function of cosmic time. We evolve one-dimensional Lagrangian shells with radiative cooling of the gas and heating due to feedback from the gas cooling and moving in towards the centre. A simple Bondi accretion model on to a central black hole is used to include feedback heating. The set-up captures some of the key characteristics of spherically symmetric accretion on to the haloes: formation of virial shocks slightly outside r(200) and long-term thermal balance in the form of cooling and heating cycles. The gas density outside our initial haloes at z = 6 is constrained by requiring that the baryon fraction within the virial radius for non-radiative evolution be equal to the universal value at almost all times. The total mass in the cold phase (taken to be similar to 10(4) K) within 40 kpc is tracked as a function of the halo mass and redshift. We compare the evolution of the cold gas mass to the observed stellar mass versus halo mass relations, following which, we can constrain the feedback energy required for different halo masses and redshifts. We also compare and match the hot gas density and temperature profiles for our most massive halo to those of clusters observed upto redshift 2. Our model is thus an improvement over the semi-analytic models in which isothermal condition and rho proportional to r(-2) are assumed
Hole Injection and Rectifying Heterojunction Photodiodes through Vacancy Engineering in MoS2
No full textThe lack of techniques for counter doping in two dimensional (2D) semiconductors has hindered the development of p/n junctions, which are the basic building blocks of electronic devices. In this work, low‐energy argon ions are used to create sulfur vacancies and are subsequently “filled” with oxygen to create p‐doped MoS2−xOx. The incorporation of oxygen into the MoS2 lattice and hence band‐structure modification reveal the nature of the p‐type doping. These changes are validated by X‐ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, Raman spectroscopy, and photoluminescence measurements combined with density functional theory calculations. Electrical measurements reveal a complete flip in carrier polarity from n‐type to p‐type, which is further examined using temperature‐dependent transport measurements. The enhancement of p‐field‐effect transistor characteristics is facilitated by employing top‐gated transistors and area‐selective vacancy engineering only in the contact regions. Finally, on the same flake, an in‐plane MoS2 (n)/MoS2−xOx (p) type‐I (straddling) heterojunction with rectifying behavior and excellent broadband photoresponse is demonstrated and explained using band diagrams. The spatial/metallurgical abruptness (<100 nm) of the heterojunctions is ascertained using Raman mapping. This process of vacancy engineering, which enables air‐stable, area‐selective, controlled, CMOS‐compatible doping of 2D semiconductors is envisioned to open new vistas in the development of high‐performance electronic and optoelectronic devices
Anomalous temperature dependence of optical and acoustic phonons in Bi2Se3 arising from stacking faults
No full textThe class of layered 3D-topological insulators have shown intriguingly anomalous temperature dependence in their thermal expansion coefficients. It was proposed that stacking faults are the origin of the observed anomalous thermal expansion. Here, using femtosecond pump-probe differential reflectivity measurements we probe the carrier and coherently generated totally symmetric A(1g) optical phonons in Bi2Se3. Transient signals also show a low frequency (similar to GHz) oscillations due to coherent longitudinal acoustic phonons. We extract temperature dependence of optical constants, sound velocity and Young's modulus of Bi2Se3 using the strain pulse propagation model. A remarkable anomalous behavior around similar to 180 K is observed in the temperature dependence of optical and acoustic phonons as well as the optical constants. First-principles density functional theory reveals that thermally activated formation of stacking faults is responsible for the anomalies observed in Bi2Se3, similar to case of Sb2Te3. We also show that inclusion of spin-orbit coupling plays an important role in reducing the total energy difference between the pristine and the faulted structures
Measurement of B-s(0) meson production in pp and PbPb collisions at root S-NN=5.02 TeV
No full textThe production cross sections of B-s(0) mesons and charge conjugates are measured in proton-proton (pp) and PbPb collisions via the exclusive decay channel B-s(0)-> J/ psi phi ->mu(+) mu(-) K+K- at a center-of-mass energy of 5.02 TeV per nucleon pair and within the rapidity range vertical bar y vertical bar < 2.4 using the CMS detector at the LHC. The pp measurement is performed as a function of transverse momentum (P-T) of the B-s(0), mesons in the range of 7 to 50 GeV/c and is compared to the predictions of perturbative QCD calculations. The B s production yield in PbPb collisions is measured in two F t intervals, 7 to 15 and 15 to 50 GeV/c, and compared to the yield in pp collisions in the same kinematic region. The nuclear modification factor (R-AA) is found to be 1.5 +/- 0.6(stat) +/- 0.5(syst) for 7-15 GeV/c, and 0.87 +/- 0.30(stat) +/- 0.1 7(syst) for 15-50 GeV/c, respectively. Within current uncertainties, the B-s(0) results are consistent with models of strangeness enhancement, and suppression by parton energy loss, as observed for the B+ mesons
Anti-inflammatory effect of synthesized indole-based chalcone (2E)-3-(4-bromophenyl)-1-(1H-indol-3-yl) prop-2-en-1-one: an in vitro and in vivo studies
No full textPurpose: Chalcones are precursors of flavonoids with a wide range of pharmacological activities. This study evaluates the anti-inflammatory effect of indole based chalcone derivative (2E)-3-(4-bromophenyl)-1-(1H-indol-3-yl) prop-2-en-1-one (IC9) on lipopolysaccharide (LPS) activated murine macrophages RAW264.7 cells and carrageenan-induced acute model in rats. Materials and methods: LPS-treated RAW264.7 cell lines and carrageenan-induced animal model were employed to evaluate the anti-inflammatory activity of IC9. The cell cytotoxicity studies were carried out by MTT assay. Reactive oxygen species (ROS) production and other inflammatory markers such as prostaglandin E2 (PGE2), nitric oxide (NO) as well as cyclooxygenase-2 (COX-2) activity were determined using ELISA. The RT-PCR was performed to determine mRNA expressions in the case of inducible nitric oxide synthase (iNOS), COX-2, Toll-like receptor-4 (TLR-4) and also nuclear translocation of NF-?B activity. Results: LPS-activated RAW264.7 cells showed an increased level of ROS generation and other inflammatory markers such as PGE2, NO level and COX-2 activity. Expression of iNOS, COX- 2 and TLR-4 mRNA expression were also up-regulated along with nuclear translocation of NF-?B. On IC9 supplementation, all the above parameters of LPS-activated cells were found to be reversed, resembling the control group. Moreover, IC9 significantly inhibited paw swelling and exhibited maximum inhibition of 78.45% at low dose of 7.5 mg/kg.bwt. Conclusions: The targeting anti-inflammatory efficacy and profound NF-?B sensitive transcriptional regulatory mechanism of IC9 accounts for its effective anti-inflammatory action