100 research outputs found
Qualitative analysis of controlled release ciprofloxacin/carbopol 934 mucoadhesive suspension
No full textMucoadhesive polymeric (carbopol 934) suspension of ciprofloxacin was prepared by ultrasonication and optimized with the aim of developing an oral controlled release gastro-retentive dosage form. The qualitative analysis of the formulation was performed by fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray powder diffraction (XRD), and scanning electron microscopy (SEM) analyses. FTIR (400 cm-1 to 4000 cm-1 region) and Raman (140 to 2400 cm-1 region) Spectroscopic studies were carried out and the spectra were used for interpretation. XRD data of pure drug, polymer and the formulation were obtained using a powder diffractometer scanned from a Bragg′s angle (2q) of 10° to 70°. The dispersion of the particle was observed using SEM techniques. The particle size distribution and aspect ratio of particles in the polymeric suspension were obtained from SEM image analysis. The results from FTIR and Raman spectroscopic analyses suggested that, in formulation, the carboxylic groups of ciprofloxacin and hydroxyl groups of C934 undergo a chemical interaction leading to esterification and hydrogen bonding. The XRD data suggested that the retention of crystalline nature of ciprofloxacin in the formulation would lead to increase in stability and drug loading; decrease in solubility; and delay in release of the drug from polymeric suspension with better bioavailability and penetration capacity. The SEM image analysis indicated that, in the formulation maximum particles were having aspect ratio from 2 to 4 and standard deviation was very less which provided supporting evidences for homogeneous, uniformly dispersed, stable controlled release ciprofloxacin suspension which would be pharmaceutically acceptable
Human Resource Practices as Predictors of Organizational Performance: A Structural Equation Modeling Approach
No full textDirect Evidence of Solid-State Tautomerism by Diffraction Methods: Isomers, Equilibria, and Kinetics
No full textHelical Water Chain Mediated Proton Conductivity in Homochiral Metal–Organic Frameworks with Unprecedented Zeolitic <i>unh</i>-Topology
No full textFour new homochiral metal–organic framework (MOF) isomers, [Zn(l-LCl)(Cl)](H2O)2 (1), [Zn(l-LBr)(Br)](H2O)2 (2), [Zn(d-LCl)(Cl)](H2O)2 (3), and [Zn(d-LBr)(Br)](H2O)2 (4) [L = 3-methyl-2-(pyridin-4-ylmethylamino)butanoic acid], have been synthesized by using a derivative of l-/d-valine and Zn(CH3COO)2·2H2O. A three-periodic lattice with a parallel 1D helical channel was formed along the crystallographic c-axis. Molecular rearrangement results in an unprecedented zeolitic unh-topology in 1–4. In each case, two lattice water molecules (one H-bonded to halogen atoms) form a secondary helical continuous water chain inside the molecular helix. MOFs 1 and 2 shows different water adsorption properties and hence different water affinity. The arrangement of water molecules inside the channel was monitored by variable-temperature single-crystal X-ray diffraction, which indicated that MOF 1 has a higher water holding capacity than MOF 2. In MOF 1, water escapes at 80 °C, while in 2 the same happens at a much lower temperature (∼40 °C). All the MOFs reported here shows reversible crystallization by readily reabsorbing moisture. In MOFs 1 and 2, the frameworks are stable after solvent removal, which is confirmed by a single-crystal to single-crystal transformation. MOFs 1 and 3 show high proton conductivity of 4.45 × 10–5 and 4.42 × 10–5 S cm–1, respectively, while 2 and 4 shows zero proton conductivity. The above result is attributed to the fact that MOF 1 has a higher water holding capacity than MOF 2
Variable Water Adsorption in Amino Acid Derivative Based Homochiral Metal Organic Frameworks
No full textSix new Cd-containing homochiral metal–organic framework materials [{Cd(L1)(Cl)}(H2O)]∞ (1a), [Cd(L1)(Br)]∞ (1b), [Cd(L2)(Cl)](H2O)]∞ (2a), [{Cd2(L2)2(Br)2}(H2O)3]∞ (2b) [{Cd(L3)(Cl)}(H2O)2]∞ (3a), and [{Cd(L3)(Br)}(H2O)2]∞ (3b) [L1 = 2-((pyridin-4-yl)methylamino)-4-methylpentanoic acid], [L2 = 2-(pyridin-4-yl)methylamino)-3-hydroxypropanoic acid], and [L3 = 2-((pyridin-4-yl)methylamino)-3-hydroxybutanoic acid] have been synthesized using pyridine functionalized amino acid (l-leucine, l-serine, and l-threonine) homochiral links and Cd(CH3COO)2·2H2O and characterized via single crystal X-ray diffraction (XRD), powder X-ray diffraction (PXRD), variable temperature powder X-ray diffraction (VTPXRD), thermogravimetric analysis and water adsorption experiments. Side chains in different amino acid derivatives and anions (Cl–, Br–) have been identified to play an important role in structural diversity (from porous to nonporous) as well as physical properties. These metal–organic frameworks (MOFs) exhibit a distinct water adsorption nature and capacity, e.g., high adsorption at low partial pressure based on architectural diversities
Solid-State Thermolysis of Anion Induced Metal–Organic Frameworks to ZnO Microparticles with Predefined Morphologies: Facile Synthesis and Solar Cell Studies
No full textSimple one-step solid state thermolysis of two Zn-based homochiral metal organic frameworks (MOFs) leads to a dramatic difference in morphologies which depends on the anion (-Cl and -Br) and calcination environment (air and N2). Rod-shaped (aspect ratio ∼ 20), hexagonal column shaped (aspect ratio ∼ 3), and elliptical aggregation of ZnO morphologies (aspect ratio ∼ 3) are obtained and characterized. Although these two MOFs possess similar rod-shaped morphology, they produce dramatic change in resulting ZnO microparticle morphologies (from rod-shaped ZnO microparticles in the case of thermolysis of MOF 1 to hexagonal column shaped ZnO microparticles in the case of MOF 2 thermolysis) when calcined in N2 at 800 °C. However, when we calcined both MOF 1 and 2 in air, we encountered similar elliptical aggregation of ZnO microparticles. These ZnO microparticles show permanent porosity, visible light emission centered at 605 or 510 nm. Moreover, they show 0.15% and 0.14% dye sensitized solar cell activity. To the best of our knowledge, this is the first report of dye sensitized solar cell activity of ZnO microparticles obtained from one-step thermolysis of porous homochiral MOFs
Dieulafoy lesion: A rare cause of gastrointestinal bleeding
No full textDieulafoy lesion is characterized by exteriorization of a large pulsatile arterial vessel through a minimal mucosal tear surrounded by normal mucosa, causing massive and recurrent upper digestive bleeding in previously healthy patients. More frequently presented than diagnosed, with the increase of its knowledge among endoscopists, a large number of cases are expected in the literature. Dieulafoy lesion is a distinct nosologic entity that must be suspected in patients with massive digestive bleeding. Endoscopy became the procedure of choice for diagnosis and treatment of this disease
Relating pore hydrophilicity with vapour adsorption capacity in a series of amino acid based metal organic frameworks
No full textA new Zn based porous homochiral metal–organic framework, ThrZnOAc, belonging to unh topology, has been synthesized using pyridyl functionalized threonine and Zn(OAc)2 as the metal precursor. Stepwise substitution of the homochiral MOF backbone by simply changing the sidearm of the amino acids (isopropyl in the case of valine, methyl in alanine and hydroxyethyl in threonine) resulted in increased water adsorption in ThrZnOAc compared to the previously reported ValZnOAc/AlaZnOAc. Extensive solvent sorption isotherms (water, methanol, isopropanol and toluene) have been carried out, which revealed high solvophilic interaction with polar solvents in ThrZnOAc due to the polar pore [2-hydroxyethyl {–CH(OH)CH3} sidearm of the amino acid], which is not prominent in the corresponding valine/alanine counterparts. The aforementioned functionalization in a series of isostructural amino acid based MOFs with the only difference being in the sidearm and their emergence as enhanced solvophilic materials is unprecedented in the MOF literature
Alkali earth metal (Ca, Sr, Ba) based thermostable metal–organic frameworks (MOFs) for proton conduction
No full textThree new alkaline earth metal based MOFs have been synthesized by using 4,4′-sulfobisbenzoic acid (SBBA) and alkaline earth metal salts M(NO3)2, M = Ca, Sr, Ba. These MOFs exhibit interesting structural diversity, variable chemical stability as well as proton conductivity
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