Multiple fragmentation of wave packets in a nonlinear medium with normal dispersion of the group velocity

The features of the dynamics of the self-ffects of the wave field are considered for the case when the dynamics is described by the nonlinear Schrodinger equation (NSE) with a hyperbolic spatial operator. An analytical investigation of the characteristic regimes of the self-effects is carried out; these regimes are due to the spatial competition of the self-focusing compression of the wave packet in one direction and its defocusing in another. The initial distributions of the wave field are analyzed with the goal of using them in a numerical modeling for illustration of the features of the self-effects. It is shown that three stages can be discerned in the evolution of the localized distributions: self-focusing filamentation of the wave field in the transverse direction, and compression and subsequent fragmentation in the defocusing (longitudinal) direction. The strongest non-uniformities are excited in the self-similar collapse of the wave field to hyperbolas (to the characteristic curves of the hyperbolic operator of the NSE). The stabilization of the development of the fragmentation instability is discussed separately.     

Influence of heat transfer on a peristaltic transport of Herschel–Bulkley fluid in a non-uniform inclined tube

Peristaltic transport in a two-dimensional non-uniform tube filled with Herschel–Bulkley fluid is studied under the assumptions of long wavelength and low Reynold number. The fluid flow is investigated in the wave frame of reference moving with the velocity of the peristaltic wave. Exact solution for the velocity field, the temperature profile, the stream functions and the pressure gradient are obtained. The physical behavior of τ, n, α and on the pressure rise versus flow rate are discussed through graphs. At the end of the article trapping phenomena for Herschel–Bulkley and also for Newtonian, Bingham and power law (which are the special cases of Herschel–Bulkley fluid) fluid are discussed.     

Chemical tuning of positive and negative magnetoresistances, and superconductivity in 1222-type ruthenocuprates

A remarkable variety of conducting states has been found in RuSr2(R2-xCex)Cu2O10-delta ruthenocuprates by tuning the properties of the magnetic CuO2 and RuO2 layers through small changes in the chemistry of the (R,Ce)2O2-delta slab. Both the R3+ cation size and the charge transfer determined by the R/Ce ratio and the oxygen deficiency delta are important controlling parameters that tune ground-state properties from positive magnetoresistive to negative magnetoresistive to superconducting.     

An alytical and numerical study of peristaltic transport of a Johnson-Segalman fluid in an endoscope

In the present study, we discuss the peristaltic flow of a Johnson-Segalman fluid in an endoscope. Perturbation, homotopy, and numerical solutions are found for the non-linear differential equation. The comparative study is also made to check the validity of the solutions. The expressions for pressure rise frictional forces, pressure gradient, and stream lines are presented to interpret the behavior of various physical quantities of the Johnson-Segalman fluid.     

Fission studies of gold induced by (1665 MeV) π- using a CR-39 detector

The fission cross section and fission probability of ¹⁹⁷Au, induced by (1665 MeV) π^-, have been studied using CR-39 track detectors. A 4π-geometry was used to count track statistics. A beam of negative pions of 1665 MeV was produced at AGS of Brookhaven National Laboratory, USA, and allowed to fall normally on the stack. Two detectors from the stack were scanned for fission fragment tracks after etching in 6N NaOH at 70℃. The statistics of fission fragment tracks in both detectors were obtained. It was found that there was a marked asymmetry of registered tracks with respect to the forward and backward hemispheres. This asymmetry could be partly accounted for on the basis of momentum transfer to the struck nucleus. On the basis of counting statistics fission cross section was measured, and fission probability was determined by dividing the fission cross section with the reaction cross section. The fission cross-section and fission probability were compared with the computed values using the cascade-exciton model code CEM95.     

FTIR analysis of natural and synthetic collagen

Collagen is the most abundant protein in humans and animals, comprising of one third of the total proteins that accounts for three quarters of the dry weight skin in humans. Collagen containing a range of proteins has been reported for tissue engineering applications, but, only a small number of studies related to chemical structure evaluation of collagen are found in the literature. Collagen can be obtained from both the natural and synthetic sources and offers a wide range of biomedical applications due to its excellent biocompatibility and low immunogenicity. Hence, it is important to identify chemical structural properties of collagen and Fourier transform infrared (FTIR) appears to be a technique of choice to study their chemical structure. This review aims to highlight the use of FTIR to study collagen-based biomaterials, using it for characterization of collagen extracted from various sources. Characterization of collagen-based materials used in wound healing, skin substitutes, derma fillers, and aging of skin, collagen containing drug delivery agents, collagen-based materials used in tissue engineering, bone regeneration, and osteogenic differentiation is discussed in detail. FTIR analysis of collagen-containing materials used for dental applications, cleft-palate, and in alveolar-ridge preservation has also been highlighted.     

Isolation and Identification of Bioactive Compounds from Bidens spp. Using HPLC-DAD and GC-MS Analysis and Their Biological Activity as Anticancer Molecules

The genus Bidens a member of family Compositae, is widely documented as an ethno-medicinally important genus of plants. In the present study, anticancer potential of three ethno-medicinally important species i.e., B. bipinnata, B. biternata and B. pilosa were tested. For in-vitro evaluation, an MTT (Thiazolyl blue tetrazolium bromide) assay was performed against cervical cancer cells (HeLa), hepatocellular carcinoma (HepG), and adenocarcinoma human alveolar basal epithelial cells (A549). For in vivo evaluation, Artemia salina, Danio rerio, and Caenorhabditis elegans were used. Among all the tested extracts, the ethanol extract of B. biternata appeared to have highest anticancer activity, and the compounds responsible for this activity were identified to be Tris (2,4-di-tert-butylphenyl), 4-hydroxy-2,4′-dimethoxychalcone, and 2,4-di-tert-butylphenol. This is the first report of the isolation of Tris (2,4-di-tert-butylphenyl) phosphate from the genus Bidens and the first report of 4-hydroxy-2,4′-dimethoxychalcone and 2,4-di-tert-butylphenol from B. biternata. Among the isolated compounds, 4-hydroxy-2,4′-dimethoxychalcone showed the highest anticancer activity with an LD50 value of 236.7 µg/mL. Therefore, this compound carries promising potential for being established as a pharmaceutical for chemoprevention and chemotherapy.     

Comparative isoconversional thermal analysis of Artemisia vulgaris hydrogel and its acetates; a potential matrix for sustained drug delivery

Abstract

Artemisia vulgaris hydrogel (AVH) was acetylated (AAVH) and characterized by FTIR, CP/MAS ¹³C-NMR spectroscopic techniques and thermogravimetric analysis. Flynn–Waal–Ozawa model was used to investigate thermal degradation kinetics. Energy of activation (Ea) values of first and major thermal degradation steps were found to be 128.14 and 116.85 kJmol^?1 for AVH and AAVH, respectively. Thermodynamic triplet, order of degradation reaction, integral procedural decomposition temperature (IPDT) and comprehensive index of intrinsic thermal stability (ITS) were also taken into account. In vitro caffeine release from AVH-based matrix tablets indicates potential of AVH for the development of oral delivery systems for sustained drug release.     

Is Coleman-Weinberg symmetry breaking in the standard model ruled out?

In the standard model with Coleman-Weinberg symmetry breaking a symmetric vacuum (〈φ〉 = 0) always exists at any non-zero temperature; the transition to the symmetry-breaking vacuum can only occur after much supercooling. Witten has shown that this transition occurs when the strong interactions break chiral symmetry; the transition temperature is O(200) MeV and a large (but not fatal) amount of entropy is produced. It is noted here that since the strong coupling grows as the universe cools in the metastable symmetric vacuum, the Yukawa coupling to the top quark will also grow. This causes top quark loops to dominate the effective potential at small scales, drastically altering the nature of the transition. We show that if $\text{m}{}_{\mathrm{<mtext>t</mtext>}}\text{? 65}\text{GeV}$, a metastable vacuum at 〈φ〉 ≈ 0(1) GeV forms which persists to T = 0; the resulting transition would generate far too much entropy to be compatible with the current baryon to entropy ratio, ruling out the CW mechanism. If m_t ? 65 GeV, we argue that a metastable vacuum might also exist, but a breakdown of perturbation theory precludes a definitive statement.