Cellulose - In this paper, we report the effect of doping sodium iodide (NaI) salt into a polymer blend matrix of sodium carboxymethyl cellulose (NaCMC) and poly(vinyl alcohol) (PVA). Solution... 相似文献
A simple, sensitive, selective, precise and stability indicating high-performance thin-layer chromatographic method was developed for the determination of tamsulosin (TAM) in bulk and tablet formulation. Validation was carried out in compliance with International Conference on Harmonization guidelines. The method employed thin-layer chromatography aluminium plates pre-coated with silica gel 60F254 as the stationary phase and the mobile phase consisted of acetonitrile/methanol/dichloromethane (2.0: 1.0: 2.0, v/v/v). This solvent system was found to give compact spots for tamsulosin (Rf = 0.27 ± 0.02). Densitometric analysis of TAM was carried out in the absorbance mode at 286 nm. Linear regression analysis showed good linearity (r2 = 0.9993) with respect to peak area in the concentration range of 300–800 ng per band. The method was validated for precision, accuracy, ruggedness and recovery. Limits of detection and quantitation were 8.49 and 25.72 ng per band, respectively. TAM was subjected to acid and alkali hydrolysis, oxidation, photo degradation, dry heat and wet heat treatment. The drug underwent degradation under acidic, basic and photolytic conditions. The degraded products were well separated from the pure drug. Statistical analysis proved that the developed method, used for quantification of TAM as a bulk drug and present in pharmaceutical tablets, was reproducible and selective.
Research on Chemical Intermediates - The synthesis of a new series of triazole-biscoumarin conjugates by using a molecular hybridization approach is described. The newly synthesized compounds... 相似文献
Nitrogen doped TiO2 (TiO2−xNx) with a homogenous anatase phase was synthesized, using β-alanine as a nitrogen precursor and ethanol as a oxygen depriving
agent in the concentration range of 0.05, 0.10, 0.15 and 0.2 at% and were characterized by Powder X-ray Diffraction (PXRD),
X-ray Photoelectron Spectra (XPS), Scanning Electron Microscope (SEM), Fourier Transform Infrared (FT-IR) and UV–visible Diffused
Reflectance Spectroscopic (DRS) techniques. Ethanol deprives the surface oxygen, thereby generating oxygen defects whose concentration
was evaluated by FTIR, Photoluminescence (PL) and Electron Spin Resonance (ESR) studies. FTIR analysis reveal that concentration
of oxygen vacancies/defects (Vo) decreases as the nitrogen concentration increases leading to the reduction in the Ti–O bond length. This results in a shift
of the IR absorption peak towards a low wave number as predicted by simple physical harmonic oscillator model. The Ti 2p3/2 XPS spectra of TiO2−xNx shifts to lower binding energies due to the increase in the electron densities around the Ti atoms indicating the formation
of Ti3+ in the doped samples. N2 adsorption–desorption isotherms measurements show a slight increase in the Brunner–Emmet–Teller (BET) surface area, pore
diameter, mesopore volume, while the crystallite size and the morphology were also effected by the nitrogen doping. The equilibrium
adsorption of Toluene molecules on the photocatalyst surface follows Langmuir theory and the rate controlling step could be
the surface reaction of the adsorbed Toluene molecules. 相似文献
Chitosans with high degree of polymerization and molecular weight exhibit poor aqueous solubility which is an impediment in
their applicability. The low molecular weight chitosans (LMWCs) and chitooligosaccharides (COSs) can be used to avoid this
hurdle. The development of an efficient process for reducing the molecular weight of chitosan, without altering its chemical
structure, is of great interest to produce tailormade chitosans of varying Degree of Acetylation (DAs) and Degree of Polymerization
(DPs). The production of well-defined COS-mixtures, or even pure COS, is of great interest since these oligosaccharides are
thought to have several interesting bioactivities and applications. For this proper delineation of their characteristics is
needed. Hence it is our attempt to provide an overview of difffernt methods and techniques of their production and characterization.
Several methods viz. depolymerization under the action of reagents, enzymes, high energy impact and combinations thereof have
been employed to get COS by depolymerization of high molecular weight chitosans. Acid hydrolysis (hydrochloric, nitrous, phosphoric
acid, hydrogen fluoride) and oxidative reductive depolymerization (mediated by peroxide, ozone, and persulfate) are important
routes for synthesis of COSs. These oligomers can be produced from chitin or chitosan as a starting material by enzymatic
conversions. For this, numbers of enzymes have been used. Depolymerization under high energy impact and recombinant approaches
are also being tried for production of COSs. LMWC and COS, like parent chitosan, can be used for drug delivery and gene delivery.
The efficient and productive processes are needed for separation of COSs into its components or mixture of defined characters.
The characterization of COS can be carried out by chromatographic and spectroscopic techniques. Importantly COSs display an
array of biological activities as antimicrobial, anticancer/antimetastatic, wound healing acceleration, immunostimulation,
apoptosis induction or inhibiton, antioxidant, enzyme inhibiton, antihyperlipidemic, antidiabetic, chemoprevention, and many
more. A few of the biological actions are reported only sporadically where as some are persistently taken up by the scientific
fraternity to substantiate the claims and propose possible mechanisms of action. However there remains the disagreement of
results on COS activities. The disagreements can arise due to poor and variable reporting of the properties of COS such as
used in the studies as molecular weight, degree of acetylation, molecular weight distribution, and the pattern of N-acetylation
etc. With production of COS of well defined characters it might be possible to understand the modes of actions of COS in better
ways. 相似文献
The kinetics of copper ion (Cu(II)) removal from aqueous solution by pyrolytic tire char was modeled using five different conventional models. A modification to these models was also developed through a modified equation that accounts for precipitation. Conventional first- and second-order reaction models did not fit the copper sorption kinetics well, indicating a lack of simple rate-order dependency on solute concentration. Instead, a reversible first-order rate reaction showed the best fit to the data, indicating a dependence on surface functional groups. Due to the varying solution pH during the sorption process, modified external and internal mass transfer models were employed. Results showed that the sorption of copper onto oxygenated chars was limited by external mass transfer and internal resistance with and without the modification. However, the modification of the sorption process produced very different results for unoxygenated chars, which showed neither internal nor external limitation to sorption. Instead, its slow sorption rate indicates a lack of surface functional groups. The sorption of Cu(II) by oxygenated and unoxygenated chars was also found to occur via three and two distinct stages, respectively. 相似文献
In the present investigation, a series of 4‐((3‐(trifluoromethyl)‐5,6‐dihydro‐[1,2,4]triazolo[4,3‐a]pyrazin‐7(8H)‐yl)methyl)benzenamine analogs 6a–o were synthesized and characterized by IR, NMR (1H and 13C), and mass spectra. All newly synthesized compounds 6a–o were prepared under conventional and microwave irradiation methods. These compounds obtained in higher yields and in shorter reaction times in the microwave irradiation method when compared with the conventional method. Synthesized compounds 6a–o were inspected for their in vitro antitubercular activity against Mycobacterium tuberculosis H37Ra using an established XTT reduction menadione assay. Among the screened compounds, 6i (IC50: 1.82 μg/mL), 6j (IC50: 1.02 μg/mL), and 6k (IC50: 1.59 μg/mL) showed excellent activity. Furthermore, compound 6i showed MIC90 value of 16.02 μg/mL. In summary, the results indicate the identification of some novel, selective, and specific inhibitors against M. tuberculosis that can be explored further for the potential antitubercular drug. 相似文献
In the present study, substituted formylnaphthalenyloxymethyl‐triazolyl‐N‐phenylacetamide derivatives ( 6a – k ) have been designed and synthesized employing click chemistry approach and evaluated for their in vitro antifungal and antibacterial activities. All the newly synthesized compounds were thoroughly characterized by 1H NMR, 13C NMR, and HRMS spectral techniques. Among the screened compounds, 6d , 6e , 6j , and 6k have shown good antifungal and antibacterial activities. Compound 6k has shown very effective antimicrobial activity. We further performed exploratory docking studies on microbial DNA gyrase to rationalize the in vitro biological data and to demonstrate the mechanism of antimicrobial activity. This is the first report to demonstrate the formylnaphthalenyloxymethyl, triazole, and N‐phenylacetamide hybrids as potential antimicrobial agents. 相似文献
Research on Chemical Intermediates - A series of (2-amino-3-cyano-4H-chromen-4-yl) phosphonic acid diethyl ester derivatives were synthesized from salicylaldehyde, malononitrile and... 相似文献
Journal of Thermal Analysis and Calorimetry - The carbon nanotubes are considered as one of the highest thermal conductive material which is having a variety of heat transfer applications. The... 相似文献