Search

This article deals with the numerical solution of a singularly perturbed initial–boundary value problem (IBVP) with two parameters on a rectangular space–time domain. A fully-discrete numerical method by combining the Crank–Nicolson scheme for temporal derivative and the streamline-diffusion finite element method (SDFEM) for spatial derivatives has been established in a new theoretical framework. A suitable stabilization parameter has been explored on some conditions related to error analysis. The robust error estimates and the stability results are obtained by using P 1 -finite element in the discrete L 2 (0 , T ; SD) -norm. Theoretical results are verified by some numerical experiments. [ABSTRACT FROM AUTHOR]

Separation of Am3+and Cm3+is one of the most challenging problems in the back-end of the nuclear fuel cycle. In the present work, we exploited the cooperative effect of the opposite selectivity of hydrophobic branched DGA derivatives and hydrophobic N-donor heterocyclic ligands taken in two different phases to achieve improved separation behavior. A systematic study was performed using a series of DGA derivatives to understand the effect and the position of branching in the alkyl chains on the separation behavior of Am3+and Cm3+. A separation factor (S.F.) value as high as 10 for Cm3+over Am3+was obtained in the case of TiBDGA (N,N,N′,N′-tetra-iso-butyl diglycolamide) using SO3PhBTPhen ((phenanthroline-2,9-diyl)-1,2,4-triazine-5,5,6,6-tetrayltetrabenzenesulfonic acid) as the aqueous complexant, which is the highest reported value so far for the ligand-based separation of Am3+and Cm3+without involving any oxidation or reduction step. The high selectivity favoring Cm3+ion extraction in the case of this DGA derivative is also explained with the help of computational studies.

A new $${\mathcal {C}}^1$$ C1 -rational cubic fractal interpolation surface is introduced to interpolate the surface data which lies on a rectangular grid. At the beginning, $${\mathcal {C}}^1$$ C1 -rational cubic fractal interpolation functions are constructed along the grid lines. Then, the $${\mathcal {C}}^1$$ C1 -rational cubic fractal interpolation surface is constructed with the help of blending functions and the rational cubic fractal interpolation functions. Convergence analysis of the fractal interpolation surface to an original function is carried out. Further, the scaling factors and the shape parameters are constrained, so that the fractal interpolation surface would lie above the fixed plane whenever the surface data lie above the plane. Also, conditions on the scaling factors and the shape parameters are derived to interpolate the convex surface data.

Terbinafine (TRB) is an allylamine antifungal agent that has been available for more than a decade. It is now used for the treatment of dermatophytic infections and onychomycosis. Despite several studies having demonstrated the efficacy of terbinafine against nondermatophytic infections including azole-resistant candidiasis, invasive aspergillosis, disseminated fusariosis and scedosporiosis, the role of TRB in the management of these infections remains greatly underappreciated. A brief review of pharmacodynamic, pharmacokinetic, in vitroand in vivodata and published case reports provides insight into the use of terbinafine as a potential adjunct in combination with azoles, polyenes or echinocandins in the management of severe drug-resistant or refractory mycoses. Despite the lack of intrinsic fungicidal activity against several nondermatophytes, when used in combination, particularly with azoles, TRB has demonstrated good antifungal efficacy that could be exploited in clinical practice. As comprehensive human clinical studies are not feasible with the rare occurence of these mycoses, experiments using animal models are essential to evaluate the in vivoefficacy of drug combinations. In summary, terbinafine has established itself as a drug of choice for dermatophytic infections; it must be considered in combination with other antifungal agents for the management of nondermatophytic refractory or resistant yeast/mold infections as well.

Synthetic fibers made from nylon or polypropylene have gained application when loose and woven into geo textile form although no information on the matrix’s mechanical performance is obtained so that more understanding of their structural contribution to resist cracking can be determined. This paper presents the results of an experimental investigation to determine the performance characteristics of concrete reinforced with a polypropylene structural fiber. In this investigation “Fiber mesh” brand of fibers manufactured by SL Concrete System, Tennessee, USA and marketed by M/S Millennium Building System, Inc., Bangalore, India are used. The lengths of the fibers used were 24 mm. Fiber dosages used were 0.9, 1.8, 2.7 kg/m3. A total of three mixtures, one for each fiber dosage were made. A standard slump cone test was conducted on the fresh concrete mix with and without fibers to determine the workability of the mix. The test program included the evaluation of hardened concrete properties such as compressive, split tensile, modulus of rupture and flexural strengths. The increase in compressive strength is about 36.25%, 26.20%, and 23.75% respectively that of plain concrete. This increase in strength was directly proportional to amount of fibers present in the mix. The increase in flexural strength for Mixes I∼III is about 21%, 16.6%, and 23% respectively that of plain concrete specimens. An experimental investigation was also made to study the behaviors of reinforced fibers concrete beams (with longitudinal reinforcements) under two-point loading. The deflection and crack patterns were also studied. The improvements in strength and ductility characteristics were discussed.

Singularly perturbed Robin problems are considered in this paper. In order to get an improved numerical solution to these problems, a computational method (“Booster Method”) is suggested. In this method, an asymptotic approximation is incorporated into a finite difference scheme to improve the numerical solution. Error estimates are proposed when implemented in known difference schemes. Numerical examples are presented to illustrate the present method.

Calix[4]arene and its diphosphorylated derivative have been immobilized onto cross-linked polystyrene beads through an etherification reaction. The supported calixarene complexes 96.7% Cs(I) from a 10^-4 N solution in 1 M NaOH. Poly(hydroxystyrene) complexes 35.6% Cs(I) from the same solution. Immobilization of the calixarene onto a polymer support thus does not affect its inherently high affinity for cesium ions. Substituting two of the three remaining hydroxyl groups on the calixarene with diethoxyphosphoryl moieties allows for quantitative complexation of Fe(III) and Pb(II) from 0.01 M nitric acid solutions. The unsubstituted calixarene complexes 6.00% Fe(III) and 7.36% Pb(II) while diethoxyphosphoryl-substituted poly(hydroxystyrene) complexes 10.0% Fe(III) and 3.76% Pb(II). The calixarene therefore acts as a platform on which ligands can be immobilized in close enough proximity to permit cooperative binding of metal ions.

Calixarenes are macrocyclic compounds with four to eight repeat units formed by the condensation of p-alkylated phenols with formaldehyde. Substitution with ion-complexing ligands can allow for the synthesis of a wide array of selective coordinating compounds. Phosphorus-containing ligands have been found to complex a large number of metal ions with selectivity being determined by the precise ligand structure. The coordination chemistry that results when calixarenes are phosphorylated is reviewed to emphasize the unique potential of such molecules for selective metal ion separations and in ion sensor technology. The three sections of this review are (a) transition metal complexes of phosphorylated calixarenes (e.g., phosphino, phosphinite, and phosphine-functionalized calixarenes), (b) application of phosphorylated calixarenes as selective metal ion complexants, and (c) immobilization of calixarenes onto inorganic and organic polymers.

A numerical method for singularly-perturbed self-adjoint boundary-value problems for second-order ordinary differential equations subject to Neumann boundary conditions is proposed. In this method (booster method), an asymptotic approximation is incorporated into a finite-difference scheme to improve the numerical solution. Uniform error estimates are derived for this method when implemented in known difference schemes. Numerical examples are presented to illustrate the present method.

An improved numerical method is presented for singularly perturbed Robin problems in this paper. In this method ("Booster method"), an asymptotic approximation is incorporated into a finite difference scheme to improve the numerical solution. Error estimates are proposed for the present method. In order to show the efficiency numerical examples are presented.

A numerical method for singularly perturbed two-point boundary-value problems for second-order ordinary differential equations subject to Neumann boundary conditions is proposed. In this method, the given interval (the domain of definition of the differential equation) is divided into one 'outer region' and two 'inner regions'. Two initial-value problems associated with the inner region will be derived from the given boundary-value problem. One boundary-value problem derived from the given problem will correspond to the outer region. In each of the two inner regions an initial-value problem is solved by the fourth-order Runge-Kutta method. The boundary-value problem in the outer region is solved by a classical finite difference scheme. A combination of the solutions so obtained yields a numerical solution of the boundary-value problem on the whole interval. The implementation of the method on parallel architectures is discussed. Numerical examples are presented in support of the proposed method.

An improved numerical method for singularly-perturbed two-point boundary-value problems for second-order ordinary differential equations subject to Neumann-type boundary conditions is proposed. In this method, an asymptotic approximation is incorporated into a finite-difference scheme to improve the numerical solution. Uniform error estimates are derived when implemented in known difference schemes. Numerical results are presented in support of the proposed method.

The initial-value technique that was originally developed for solving singularly-perturbed nonturning-point problems (Ref. 1) is used here to solve singularly-perturbed turning-point problems exhibiting twin boundary layers. In this method, the required approximate solution is obtained by combining solutions of the reduced problem, an initial-value problem, and a terminal-value problem. Error estimates for approximate solutions are obtained. The implementation of the method on parallel architectures is discussed. Numerical examples are presented to illustrate the present technique.

A class of singularly perturbed two-point boundary-value problems for second-order ordinary differential equations arising in chemical reactor theory is considered. In order to solve them numerically, a method is suggested in which the given interval (the domain of the definition of the differential equation) is divided into two subintervals called inner and outer regions. In the inner region an initial-value problem for system of two first-order differential equations is solved based on the uniformly valid exponentially fitted different schemes. The boundary-value problem in the outer region is solved by classical finite difference schemes. A combination of the solution so obtained yields a numerical solution of the boundary-value problem on the whole interval. Error estimates are derived. Numerical examples are presented to illustrate the method. The implementation of the method on parallel architectures is discussed.

YY1 is a multifunctional transcription factor that acts as an activator or repressor in different contexts. YY1 binds to multiple sites in the mouse c-fos promoter, inducing at each site a sharp DNA bend. Binding of YY1 to a site situated between the cyclic AMP response element (CRE) and the TATA box bends the DNA in a way that interferes with the interaction of proteins bound at the CRE and TATA elements, resulting in repression of transcription. Here, we show that binding of YY1 to a different site in the c-fos promoter has a different result. Binding of YY1 to the c-fos serum response element (SRE) enhances the binding of serum response factor (SRF). This enhancement requires the binding of YY1 to SRE DNA. YY1 and SRF can cooccupy the SRE at least transiently. In the region of overlapping contact, YY1 contacts DNA in the major groove, while SRF contacts DNA in the minor groove. YY1 also enhances the association of SRF with the SRE in transfected insect cells. Thus, although YY1 induces similar structural changes in DNA at different binding sites, it can have distinct local effects on protein-DNA and protein-protein interactions. These data support a general role for YY1 in the building of highly organized promoter complexes.

An initial-value technique is presented for solving singularly perturbed two-point boundary-value problems for linear and semilinear second-order ordinary differential equations arising in chemical reactor theory. In this technique, the required approximate solution is obtained by combining solutions of two terminal-value problems and one initial-value problem which are obtained from the original boundary-value problem through asymptotic expansion procedures. Error estimates for approximate solutions are obtained. Numerical examples are presented to illustrate the present technique.

In this article, we propose a new numerical method based on fractal cubic spline for the numerical approximate solutions of linear and nonlinear singular two-point boundary-value problems. Error analysis of the proposed method is examined and it is shown that proposed method has second-order convergence. Numerical examples are provided to validate the theoretical results.

Ornithine carbamoyltransferase (OCT) and arginase, but not arginine synthetase (AS), were detected in the body wall and gut tissues of the leech. The activities of these enzymes were not altered by starvation. The high activity of arginase in body wall is probably due to the association of the latter with botryoidal tissue. Hirudineans, which evolved from oligochaete ancestors, appear to have lost the citrulline-arginine segment of the urea cycle due to their ammonotelic mode of nitrogen excretion.

A new numerical method is developed for approximating the solution of the fourth-order boundary-value problems with the help fractal quintic spline. The proposed method has second-order convergence. Numerical examples are experimented for the numerical illustration of the proposed method. It is shown that the method developed in this paper is more efficient than the method developed by the quintic spline.

Introduction Although the exact mechanisms that lead to degenerative disc disease (DDD) are not well understood, a significant genetic influence has been found. Focusing on DDD that occurs in young adults can be valuable in determining the exact role of genetic predisposition to DD. The present study was undertaken to assess the association between single nucleotide polymorphisms (SNPs) of candidate genes in a cohort of young Indian adults.Materials and Methods We selected young patients (age < 40 years) with lumbar disc degeneration and evaluated them with MRI and genetic association studies for 58 SNPs of 35 candidate genes. Disc degeneration of individual discs of lumbar spine from L1 to S1 was quantified by Pfirrmann grading in MRI images (1.5 T). The subjects were stratified into three groups based on a total degenerative disc score (TDDS). TDDS was developed by adding the individual scores of Pfirrmann grading of all the five lumbar discs. Based on the TDDS, the severity of DDD among the subjects was classified as mild (TDDS < 10), moderate (TDDS of 10-15), and severe (TDDS > 15). The patients were classified into three groups so that the extreme confounding patients in the mild and severe TDDS groups will automatically fall into the moderate TDDS group. For the final association analysis, only the results of mild (the unaffected, control group) and severe TDDS groups (affected, case group) were compared and analyzed.Results The study population comprised 580 subjects including 308 patients with mild TDDS, 211 patients with moderate TDDS, and 61 patients with severe TDDS. There was no significant difference in the gender difference and the mean age of the both groups. Three of the 35 candidate genes showed significant association with severe TDDS. SNPs, viz., rs1940044 of MMP (matrix metalloproteinase 7), rs2300496 SNP and rs3213718 SNPs of CALM1 (calmodulin), and rs5277 of COX 2 (cyclooxygenase) were found to be significantly associated with severe TDDS. Among the previously reported candidate genes, our analysis in the young Indian population had revealed that SNPs of COL 9, SKT, CHST 3, CILP, IGFR, SOXp, BMP, MMP 2-12, ADH2, IL1RN, AGC 1, ADAMTS5, NGFB, GLI, HHIP, TAC1, and IL1Bwere not significantly associated with severe TDDS.Conclusion This is the first of its kind in studying the genetic aspects of disc degeneration in the young adults. The study identifies specific SNP associations of three genes (MMP 7, CALM 1, and COX2) in young adults with severe lumbar disc degeneration. Genes involved in matrix degradation (MMP), intracellular signaling (CALM), and inflammation (COX 2) were associated with early disc degeneration indicating that DDD is a complex disease with an intricate interplay of multiple genetic polymorphisms. Disclosure of Interest None declared

Competing Interests: The authors declare no conflicts of interest.