On the use of overlapping lattices for screening to find pairs of nearby points in two and three dimensions

In designing an algorithm to find pairs of points that are within Euclidean distance d it is effective to use a screening procedure to reject most pairs of points that are far apart. A procedure based on multiple, overlapping lattices can efficiently identify close points and exclude distant ones.     

Frequency upconversion in Pr3+-Li2O-TeO2 binary glass by decay curve analysis

Using the decay curve analysis frequency upconversion under continuous wave NIR laser radiation ( approximately 890 nm) following the non-resonant excitation at higher energies than 1G4 level has been reported. The decay curve of the antistokes emission (3P0-->3H4) shows similar behavior as that of the stokes emission (3P0-->3H4) and does not show any rise time attributing to the excited state antistokes absorption assisted by phonon emission. The covalency, bonding parameters and nephalauxetic effect for the present system has also been determined.     

Theoretical study of diaquamalonatozinc(II) single crystal for applications in non-linear optical devices

The aim of the present paper is to employ theoretical methods to investigate the zero field splitting (ZFS) parameter and to investigate the position of the dopant in the host. These theoretical calculations have been compared with the empirical results. The superposition model (SPM) with the microscopic spin-Hamiltonian (MSH) theory and the coefficient of fractional parentage have been employed to investigate the dopant manganese(II) ion substitution in the diaquamalonatozinc(II) (DAMZ) single crystal. The magnetic parameters, viz. g-tensor and D-tensor, has been determined by using the ORCA program package developed by F Neese et al. The unrestricted Kohn–Sham orbitals-based Pederson–Khanna (PK) as the unperturbed wave function is observed to be the most suitable for the computational calculation of spin–orbit tensor (\(D^{\mathrm{SO}})\) of the axial ZFS parameter D. The effects of spin–spin dipolar couplings are taken into account. The unrestricted natural orbital (UNO) is used for the calculation of spin–spin dipolar contributions to the ZFS tensor. A comparative study of the quantum mechanical treatment of Pederson–Khanna (PK) with coupled perturbation (CP) is reported in the present study. The unrestricted Kohn–Sham-based natural orbital with Pederson–Khanna-type of perturbation approach validates the experimental results in the evaluation of ZFS parameters. The theoretical results are appropriate with the experimental ones and indicate the interstitial occupancy of \(\hbox {Mn}^{2+}\) ion in the host matrix.     

A General Existence Principle for Fixed Point Theorems in One Parameter Case of Soft $D_{a}$-Metric Space

In this paper, we take the case of soft points into consideration and propose a new metric structure called soft D_a-metric space for a specific orbit defined with soft points. In order to establish fixed point results in the modified metric space, we modify a few existing definitions in the sense of soft points.     

Poly(γ‐glutamic acid)/Silica Hybrids with Calcium Incorporated in the Silica Network by Use of a Calcium Alkoxide Precursor

Current materials used for bone regeneration are usually bioactive ceramics or glasses. Although they bond to bone, they are brittle. There is a need for new materials that can combine bioactivity with toughness and controlled biodegradation. Sol‐gel hybrids have the potential to do this through their nanoscale interpenetrating networks (IPN) of inorganic and organic components. Poly(γ‐glutamic acid) (γ‐PGA) was introduced into the sol‐gel process to produce a hybrid of γ‐PGA and bioactive silica. Calcium is an important element for bone regeneration but calcium sources that are used traditionally in the sol‐gel process, such as Ca salts, do not allow Ca incorporation into the silicate network during low‐temperature processing. The hypothesis for this study was that using calcium methoxyethoxide (CME) as the Ca source would allow Ca incorporation into the silicate component of the hybrid at room temperature. The produced hybrids would have improved mechanical properties and controlled degradation compared with hybrids of calcium chloride (CaCl₂), in which the Ca is not incorporated into the silicate network. Class II hybrids, with covalent bonds between the inorganic and organic species, were synthesised by using organosilane. Calcium incorporation in both the organic and inorganic IPNs of the hybrid was improved when CME was used. This was clearly observed by using FTIR and solid‐state NMR spectroscopy, which showed ionic cross‐linking of γ‐PGA by Ca and a lower degree of condensation of the Si species compared with the hybrids made with CaCl₂ as the Ca source. The ionic cross‐linking of γ‐PGA by Ca resulted in excellent compressive strength and reduced elastic modulus as measured by compressive testing and nanoindentation, respectively. All hybrids showed bioactivity as hydroxyapatite (HA) was formed after immersion in simulated body fluid (SBF).     

Localized electric field induced transition and miniaturization of two‐phase flow patterns inside microchannels

Strategic application of external electrostatic field on a pressure‐driven two‐phase flow inside a microchannel can transform the stratified or slug flow patterns into droplets. The localized electrohydrodynamic stress at the interface of the immiscible liquids can engender a liquid‐dielectrophoretic deformation, which disrupts the balance of the viscous, capillary, and inertial forces of a pressure‐driven flow to engender such flow morphologies. Interestingly, the size, shape, and frequency of the droplets can be tuned by varying the field intensity, location of the electric field, surface properties of the channel or fluids, viscosity ratio of the fluids, and the flow ratio of the phases. Higher field intensity with lower interfacial tension is found to facilitate the oil droplet formation with a higher throughput inside the hydrophilic microchannels. The method is successful in breaking down the regular pressure‐driven flow patterns even when the fluid inlets are exchanged in the microchannel. The simulations identify the conditions to develop interesting flow morphologies, such as (i) an array of miniaturized spherical or hemispherical or elongated oil drops in continuous water phase, (ii) “oil‐in‐water” microemulsion with varying size and shape of oil droplets. The results reported can be of significance in improving the efficiency of multiphase microreactors where the flow patterns composed of droplets are preferred because of the availability of higher interfacial area for reactions or heat and mass exchange.     

NIR to visible frequency upconversion in Er3+ and Yb3+ codoped ZrO2 phosphor

The ZrO₂:Er³⁺ codoped with Yb³⁺ phosphor powders have been prepared by the urea combustion route. Formation of the compounds ZrO₂:Er³⁺ and ZrO₂:Er³⁺, Yb³⁺ was confirmed by XRD. The frequency upconversion emissions in the green and red regions upon excitation with a CW diode laser at ～978 nm are reported. Codoping with Yb³⁺ enhances the emission intensities of the triply ionized erbium in the green and red spectral regions by about ～130 and ～820 times respectively. The emission properties of the ZrO₂:Er³⁺ phosphor powders are discussed on the basis of excited state absorption, energy transfer, and cross-relaxation energy transfer mechanisms.     

Optical studies of Dy doped tellurite glass: Observation of yellow-green upconversion

Optical absorption and fluorescence spectra of Dy³⁺ doped tellurite glass have been studied and Judd-Ofelt theory has been used to derive its optical properties. The effect of temperature on the fluorescence yield and fluorescence quenching for higher concentrations of Dy³⁺ has been studied and the mechanism involved discussed. It is found that the fluorescence intensity is larger at lower temperature. The lifetime of the ⁴F_9/2 level has been measured and found to decrease with concentration as well as temperature. Intense upconversion has also been observed in the yellow-green region when pumped with NIR (∼862 nm) radiation. An explanation of the same involving energy transfer is offered.     

Nanosecond Dynamics Regulate the MIF‐Induced Activity of CD74

Macrophage migration inhibitory factor (MIF) activates CD74, which leads to severe disorders including inflammation, autoimmune diseases and cancer under pathological conditions. Molecular dynamics (MD) simulations up to one microsecond revealed dynamical correlation between a residue located at the opening of one end of the MIF solvent channel, previously thought to be a consequence of homotrimerization, and residues in a distal region responsible for CD74 activation. Experiments verified the allosteric regulatory site and identified a pathway to this site via the MIF β‐strands. The reported findings provide fundamental insights on a dynamic mechanism that controls the MIF‐induced activation of CD74.     

Electroreduction of Nitroaromatic Compounds at Electrochemically Reduced Graphene Oxide Supported Bimetallic Ag@Pd Nanorods Modified Electrodes

The design and fabrication of nanostructured electrode with high activity at low cost are crucial elements in studying the toxicity of environmental pollutants. Here, we develop a combined step of generating Electrochemically Reduced Graphene Oxide (ERGO) nanosheets on the surface of the glassy carbon electrode where an effective seed mediated growth followed by a galvanic exchange process were introduced for the direct growth of Ag core @Pd shell nanorods (Ag@Pd NRDs). The resulting electrode possesses a large surface area, interconnected porous networks, uniform distribution of bimetallic Ag@Pd NRDs with extremely thin size of Pd generation and good electrical conductivity, which are highly desirable for the electrocatalytic reduction of nitroaromatic compounds (NACs). In the fabrication step, the shell like Cu at the bimetallic NRDs acts as a sacrificial template for forming a thin layer of Pd at Ag NRDs surface by redox replacement reaction. Thus, the resultant Ag@Pd NRDs on ERGO modified electrode was profoundly tested for the electrochemical sensing of NACs with high sensitivity, selectivity and a very low detection limit of 1.8×10^?11 M. Differential Pulse Voltammetry (DPV) was used to study the linear range of 4‐nitroaniline (4‐NA) between 1.0×10^?9 M and 1.2×10^?8 M. The modified electrode exhibits better reproducibility and long term stability. In addition, the modified electrode out performed well in the real sample analysis containing NACs in the presence of different interfering cations and anions.