Fixed Point Results for Certain Contractive Self-Mappings in D-Metric Space

There have been number of generalizations of Metric spaces. D?Metric space is one such generalization initiated by Dhage [ 1 ] in 1992 and open new research area. Rhoades [ 2 ] generalized Dhage?s contractive condition by increasing number of factors and proved fixed point of self?mapping in D?Metric space. Then many authors have obtained, interesting fixed point results in D?Metric space satisfying contractive type condition.The present paper studies some fixed point theorems in D-Metric space and proved new fixed point theorem and its corollary in a bounded D?Metric space for a contractive self ? mapping

Global variation in anastomosis and end colostomy formation following left-sided colorectal resection

Background End colostomy rates following colorectal resection vary across institutions in high-income settings, being influenced by patient, disease, surgeon and system factors. This study aimed to assess global variation in end colostomy rates after left-sided colorectal resection. Methods This study comprised an analysis of GlobalSurg-1 and -2 international, prospective, observational cohort studies (2014, 2016), including consecutive adult patients undergoing elective or emergency left-sided colorectal resection within discrete 2-week windows. Countries were grouped into high-, middle- and low-income tertiles according to the United Nations Human Development Index (HDI). Factors associated with colostomy formation versus primary anastomosis were explored using a multilevel, multivariable logistic regression model. Results In total, 1635 patients from 242 hospitals in 57 countries undergoing left-sided colorectal resection were included: 113 (6·9 per cent) from low-HDI, 254 (15·5 per cent) from middle-HDI and 1268 (77·6 per cent) from high-HDI countries. There was a higher proportion of patients with perforated disease (57·5, 40·9 and 35·4 per cent; P < 0·001) and subsequent use of end colostomy (52·2, 24·8 and 18·9 per cent; P < 0·001) in low- compared with middle- and high-HDI settings. The association with colostomy use in low-HDI settings persisted (odds ratio (OR) 3·20, 95 per cent c.i. 1·35 to 7·57; P = 0·008) after risk adjustment for malignant disease (OR 2·34, 1·65 to 3·32; P < 0·001), emergency surgery (OR 4·08, 2·73 to 6·10; P < 0·001), time to operation at least 48 h (OR 1·99, 1·28 to 3·09; P = 0·002) and disease perforation (OR 4·00, 2·81 to 5·69; P < 0·001). Conclusion Global differences existed in the proportion of patients receiving end stomas after left-sided colorectal resection based on income, which went beyond case mix alone

Effect of Flow Aids on Mucoadhesive Properties of Polymeric Discs of Polyoxyethylene and Carbopol 971P

The aim of present study is to investigate the effect of flow aids on the observed in vitro mucoadhesion of two representative polymers; polyoxyethylene and Carbopol® 971P. More recently it has been shown that the addition of small amounts of certain excipients to a mucoadhesive formulation can lead to a substantial decrease in observed mucoadhesion in an in vitro test system, which suggests that formulation of these systems could be crucial in developing successful dosage forms. A series of experiments has been carried out which indicates that the presence of flow aids at high concentrations present in tablets can affect the observed ex-vivo mucoadhesive bond. Magnesium stearate (5%) exerts its negative effect on the mucoadhesion of Carbopol® 971P and polyoxyethylene combination by hindering the hydration of the polymer. Adhesion time of formulation containing 5% magnesium stearate was found 4.7±0.34 h and percent hydration of same formulation was 70.12%.Talc and colloidal silicon dioxide (Aerosil), which do not possess the same hydrophobic properties or have available divalent cations were found to be viable alternatives to magnesium stearate

Vitrification from solution in restricted space: Formation and stabilization of amorphous nifedipine in a nanoporous silica xerogel carrier.

Purpose: The goal was to find thermodynamic criteria that must be satisfied in order to prevent formation of crystalline state of drugs within a confined space (e.g., nanopores of inorganic solid). Similarly, criteria that lead to stabilization of amorphous drug within such pores were investigated. Methods: In the theoretical part, the classical thermodynamics of nucleation is applied to the conditions of a restricted space. The theoretical findings are verified using porous silica as a carrier and nifedipine as a model drug. The amorphicity of the latter is checked using XRD and thermal analysis (DTA, DSC) in combination with BET measurements. Results: It is shown that there exists a critical pore radius of a host below which the entrapped substance will solidify in an amorphous form. There also exists a critical pore radius below which the entrapped amorphous solid will not be able to crystallize. Specifically, incorporation of NIF into a silica xerogel with an average pore diameter of about 2.5 nm produces and stabilizes its amorphous form. Conclusion: Entrapment of drugs into solid nanoporous carriers could be regarded as a potentially useful and simple method for production and/or stabilization of non-crystalline forms of a wide range of drugs

Novel hybrid silica xerogels for stabilization and controlled release of drug.

Purpose: The goal was to show that incorporation of a model drug into a porous solid matrix with small enough pores should lead to composites in which the drug would be in the amorphous rather than in the crystalline state. Due to spatial constraints, the amorphous state was expected to be temporally highly stable. Methods: As a porous solid matrix silica was selected, while nifedipine served as a model drug. The silica-drug composites were prepared using a sol-gel procedure at conditions which yielded pores in the range 2-3 nm. To tune the properties of composites, two silica precursors were combined: tetraethoxysiiane (TEOS) and bis-1,2-(triethoxysilyl)ethane (BTSE). Results: In all composites the amorphous state of nifedipine was proven using several analytical methods. The amorphicity was preserved for at least several months. Drug incorporation into purely TEOS-based silica decreased significantly the release rate. Loosening the structure by addition of BTSE, while preserving the amorphicity, increased the drug dissolution rate. The dissolution behaviour was explained using a combination of the Noyes-Whitney and power law model. Conclusion: The observed release patterns could be interesting for therapies requiring a high initial drug concentration in blood plasma, followed by a slower release rate of the remaining drug

Suspensions of modified TiO2 nanoparticles with supreme UV filtering ability.

TiO2 nanoparticles (20-23 nm in size) were coated with a silica layer onto which lauric acid was strongly bound. The strong (probably covalent) bonding was proved using detailed comparative thermal analysis. The functionalized TiO2 nanoparticles exhibited significantly reduced agglomeration, both in dry and in dispersed states (in oily media). The reduced tendency towards agglomeration was consistent with contact angle measurements which showed an increased hydrophobicity of functionalized TiO2. The strong (covalent) bonding also greatly improved the stability of the nanoparticulate sample in suspensions. Finally, the UV filtering efficiency of functionalized samples was much improved when compared to non-functionalized or those functionalized using conventional stabilizers based on adsorption. This effect was consistent with our theoretical prediction in which we correlated the particle size and the UV filtering ability

A stable superconducting state at 8 K and ambient pressure inalphat−(BEDT−TTF)2I13

We report bulk superconductivity at 8 K and ambient pressure in crystals of α t (BEDT-TTF)2I3. In contrast to the earlier observed metastable superconducting state at 8 K in crystals of β-(BEDT-TTF)2I3 here the superconducting state is stable and the crystals can be prepared by tempering α-(BEDT-TTF)2I3 above 70 °C for several days. ac-susceptibility measurements show that the observed superconducting state at 8 K is a bulk property of the crystals. Resistivity measurements indicate a sharp superconducting transition at 8 K with an onset temperature of about 9 K. The upper critical fields Hc2 at 1.3 K lie between 3 and 11 T depending on the direction of the magnetic field with respect to the crystal axes. ESR- as well as NMR-measurements indicate a total transformation of the α-phase crystals into the new superconducting α t -crystals after tempering

Thin films of BEDT-TTF and BEDO-TTF radical cation salt

In this communication we describe the fabrication and characterization of thin films of the radical cation salts α-, αt-(BEDT-TTF)2I3 and (BEDO-TTF)2.4I3. Thin films of these compounds were made by evaporation of the salts in high vacuum onto several substrates. They were characterized by X-ray diffraction, scanning electron microscopy, infrared absorption, Raman scattering, de-conductivity measurements and magnetically modulated microwave absorption. Depending on the temperature of the substrate and the evaporation rate, the films of α-(BEDT-TTF)2I3 exhibit different degrees of microcrystallinity which under the right conditions can be strongly reduced to obtain relatively smooth, completely covering films. Additionally such films have a high degree of orientation with respect to the substrate plane. The conversion into films of the superconducting αt-phase is possible and the high orientation is maintained. Due to grain boundaries, the dcconductivity is thermally activated, but the single grains are superconducting. The best results in the fabrication of smooth, completely covering films were obtained with (BEDO-TTF)2.4I3 on NaCl single crystals. Here the orientation of the donor molecule with respect to the substrate plane is different from the one found in the (BEDT-TTF)2I3 salts