Search results

1

Synthesis of hydroxyapatite by using calcium carbonate and phosphoric acid in various water-ethanol solvent systems

100%

Engin A., Girgin İ.

Open Chemistry

|

2009

|

vol. 7

|

issue 4

745-751

EN

The purpose of the present study is to synthesize hydroxyapatite by using CaCO3 and H3PO4 in various water-ethanol solvent systems. It was observed from experiments that formation of ammonium phosphate compounds hindered the formation of calcium phosphates in ethanol medium. Although the reactivity was better in aqueous medium, the carbonate contents of the products obtained were above 8.5%. Best results with a carbonate content as low as 3.82% was obtained in 50% ethanol containing mixed-aqueous medium at 80°C and the FTIR analysis showed that the product was a carbonated apatite with a calculated composition of 14CaO·4.2P2O5·CO3·7.2H2O. The amorphous and porous phosphate compound obtained with a BET surface area of 106.6 m2 g−1 seems to be useful as adsorbent in wastewater treatment. Upon sintering of the amorphous product at 750°C, crystalline hydroxyapatite with a BET surface area of 25.9 m2 g−1 is obtained that may be used in biomedical applications. [...]

2

Methotrexate binding causes structural and functional changes in lung cystatin

100%

Khan M. S., Priyadarshini M., Sumbul S., Bano B.

|

2010

|

vol. 57

|

issue 4

499-503

EN

Regulation of cysteine proteinases and their inhibitors is of utmost importance in diseases like lung cancer, chronic inflammatory conditions such as asthma, emphysema, and idiopathic pulmonary fibrosis. Protease-antiprotease imbalance accelerates disease progression. In the present study, the effect of antineoplastic and antirheumatic drug methotrexate (MTX) on lung cystatin (a cysteine protease inhibitor) was studied to explore drug induced changes in functional and structural integrity of the protein. The basic binding interaction was studied by UV-absorption, FT-IR and fluorescence spectroscopy. The quenching of protein fluorescence confirmed the binding of MTX with goat lung cystatin (GLC-I). Stern-Volmer analysis of MTX-GLC-I system at different temperatures indicates the presence of static component in the quenching mechanism. The thermodynamic parameters ΔH0 and ΔS0 were -3.8 kJ/mol and 94.97 J•mol-1•K-1, respectively, indicating that both hydrogen bonds and hydrophobic interactions played a major role in the binding of MTX to GLC-I. Methotrexate (7 µM) caused complete inactivation of lung cystatin after 6 hours. The results of FT-IR spectroscopy reflect perturbation of the goat lung cystatin on interaction with MTX. Methotrexate induced loss of function change in the inhibitor could provide a rationale for the off target tissue injury caused by the drug and for the design of agents against such an injury.

3

The effect of flame coal oxidation on the solid and soluble products of its extraction

100%

Pietrzak R., Wachowska H., Nowicki P.

Open Chemistry

|

2005

|

vol. 3

|

issue 4

852-865

EN

Solid and soluble products of THF and CH2Cl2 extraction of flame coal oxidised by four different oxidising agents (peroxyacetic acid (PAA), 5% HNO3, O2/Na2CO3, air/125 °C) were studied by elemental analysis and FTIR. The extraction yield with THF was much higher than that with CH2Cl2 for all samples. The greatest changes in elemental composition were in the extracts from coal oxidised by nitric acid. The sulphur content was lowest in extracts from coal oxidised with 5% HNO3 and PAA. FTIR confirmed that coal treatment with nitric acid incorporates nitrogen into the coal structure.

4

Open-Path FTIR Spectral Radiation Intensity Of Hot Combustion Gases – Measurement And Interpretation

88%

Cięszczyk S.

Metrology and Measurement Systems

|

2015

|

vol. 22

|

issue 2

5

A Local Model and Calibration Set Ensemble Strategy for Open-Path FTIR Gas Measurement with Varying Temperature

88%

Cięszczyk S.

Metrology and Measurement Systems

|

2013

|

issue 3

6

A Multi-Band Integrated Virtual Calibration-Inversion Method for Open Path FTIR Spectrometry

88%

Cięszczyk S.

Metrology and Measurement Systems

|

2013

|

issue 2

7

PHYSICOCHEMICAL CHARACTERIZATION AND DISSOLUTION STUDIES OF SOLID DISPERSIONS OF CLOTRIMAZOLE WITH CHITOSAN

88%

Grimling B., Jasińska J., Meler J., Szcześniak M., Pluta J. M., Górniak A.

Progress on Chemistry and Application of Chitin and its Derivatives

|

2016

|

vol. 21

63-72

EN

The aim of the present study was to increase the solubility of clotrimazole. Among the methods to increase the solubility selected solid dispersions of the drug with the polymer. Chitosan was used as the polymer. Clotrimazole was incorporated into the chitosan type 652 with molar masse chitosan Mη = 429 kDa. Solid dispersions were prepared by using different ratios of clotrimazole and chitosan (1:9, 3:7, 5:5, 7:3, 9:1). Formulations were tested dissolution rate of the drug. The highest dissolution of clotrimazole, amounting to 47.95%, was observed after 60 minutes from solid dispersion prepared by grinding method and 42.84% from physical mixtures with drug-polymer weight ratio 1:9 in the presence chitosan. The solubility of the drug improved more than 37-fold. XRPD analysis indicates the presence of the clotrimazole in crystalline form in the solid dispersion obtained by kneading method.

8

THERMAL DEGRADATION OF DOUBLE CROSSLINKED HYDROGEL CHITOSAN MEMBRANES

88%

Pieróg M., Ostrowska-Czubenko J., Gierszewska-Drużyńska M.

Progress on Chemistry and Application of Chitin and its Derivatives

|

2012

|

vol. 17

71 - 78

EN

The thermal degradation behaviour of uncrosslinked and crosslinked chitosan membranes were studied by means of dynamic thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) over the temperature range 25-500ºC in nitrogen atmosphere. Modified chitosan membranes were prepared using a crosslinking method based on covalent crosslinking of chitosan with glutaraldehyde and subsequent ionic crosslinking with sodium citrate, sulfuric acid, sulfosuccinic acid and tripolyphosphate, respectively. Chemical structure of modified chitosan membranes before and after their thermal degradation was characterized by FTIR spectroscopy. Both TGA and DSC experiments as well as spectral results (FTIR spectra of thermal degradation residues) indicated some differences in the mechanism of thermal degradation of uncrosslinked and crosslinked chitosan membranes.

9

Influence of acceptor functionality on charge transfer interactions in mixtures of poly(9-vinylcarbazole) with nitroaromatic compounds

88%

Grigoras A., Barboiu V.

Open Chemistry

|

2012

|

vol. 10

|

issue 2

313-319

EN

Charge transfer interactions in mixtures of poly(9-vinylcarbazole) with three nitro compounds (4,4′dinitrodibenzyl, ethyl 3,5-dinitrobenzoate and 2,2′,4,4′-tetranitrodibenzyl) were examined. GPC shows an increase of apparent polymer weight average molecular weight (MW) in mixtures compared with pure PVK. Electron acceptors show upfield 1H-NMR shifts for all mixtures. The equilibrium association constants (k) calculated from the Benesi-Hildebrand equation are 0.511, 1.371, and 1.868 L mol−1 for PVK blends with DNDB, DNBE and TNDB, respectively. Shifts of (−NO2) stretch vibrations in mixtures support charge transfer complex formation between PVK chains and electron acceptors The ability to accept electrons decreases: TNDB>DNBE>DNDB. [...]

10

Low temperature synthesis and characterization of Mn3O4 nanoparticles

88%

Baykal A., Köseoğlu Y., Şenel M.

Open Chemistry

|

2007

|

vol. 5

|

issue 1

169-176

EN

Heating hydrous manganese (II) hydroxide gel at 85 °C for 12 hours produces Mn3O4 nanoparticles. They were characterized by X-ray powder diffraction (XRD) and infrared spectroscopy (FTIR). The particle size estimated from the SEM and X-ray peak broadening is approximately 32 nm, showing them to be nanocrystalline. EPR measurements confirm a typical Mn2+signal with a highly resolved hyperfine structure. [...]

11

Studies of the soluble part of oxidised coals

88%

Pietrzak R., Kozłowski M., Wachowska H., Yperman J.

Open Chemistry

|

2004

|

vol. 2

|

issue 2

278-289

EN

Soluble products obtained from the oxidation of four types of coal, each characterised by different degree of coalification and different degree of sulphur content, are studied. The coals are oxidised with peracetic acid (PAA) and nitric acid. Analyses are performed by Atmospheric Pressure-Temperature Programmed Reduction (AP-TPR) and Fourier Transform Infrared Spectroscopy (FTIR). The soluble products contain much more sulphur than the insoluble products of oxidation. The products obtained from the reaction with HNO3 contain higher amounts of inorganic sulphur compounds, while those obtained from the reaction with PAA are characterised by an increased content of organic sulphur species.

12

Trace metal, FTIR and phytochemical analysis of Viscum album leaves harvested from Pentaclethra macrophylla

88%

Chizoruo I. F., Onyekachi I. B., Ebere E. C.

World News of Natural Sciences

|

2019

|

vol. 25

61-71

EN

The leaves of mistletoe (Viscum album) harvested from oil bean tree (Pentaclethra macrophylla) in Imo State South Eastern Nigeria was studied. The study was aimed at carrying out trace metal, Fourier Transform Infra-red (FTIR) and phytochemical analysis of ethanol leave extracts of Viscum album harvested from Pentaclethra macrophylla. The sample for trace metal analysis was digested with a mixture of concentrated HNO3 and HClO4 at a ratio of 1:1 for 24 hours. Ethanol was then used to extract the sample meant for FTIR and phytochemical analysis. Herein, trace metal determination indicates the presence of Mg, Zn, Fe, Cu and Cr, and the concentration of Ca and Mn is at < 0.00 mg/kg. The result of the phytochemical screening demonstrates the presence of flavonoids, alkaloids, phenols, saponins and tannins. FTIR analysis confirmed the presence of alcohols, amides, aromatics and carbonyl compounds in ethanol extracts of Viscum album harvested from Pentaclethra macrophylla. The presence of some trace metals and phytochemicals, as well as some important functional groups in the plant sample, as indicated by the result of the study, authenticates its use in traditional medicine.

13

THE INFLUENCE OF A DENTAL FORMULATION PREPARED WITH CHITOSAN ON THE PHARMACEUTICAL AVAILABILITY OF CLOTRIMAZOLE

75%

Grimling B., Meler J., Szcześniak M., Kocoń M., Karolewicz B., Złocińska A., Górniak A.

Progress on Chemistry and Application of Chitin and its Derivatives

|

2017

|

vol. 22

42-53

EN

The present work involves the development of a dental gel composition obtained on the basis of clotrimazole incorporated into chitosan in order to improve drug solubility. Solid dispersions were prepared by using two methods: grinding and kneading. The solid dispersion varied the ratio of chitosan to drug to increase the volume of the drug; the ratios were 5:5, 3:7, 2:8, 1:9. The mixtures were subjected to the dissolution rate of clotrimazole. The presence of chitosan improved the drug solubility; a better solubility from the solid dispersion prepared by the grinding method was obtained from the ratio of drug to polymer of 1+9. The rate of dissolution of clotrimazole was improved 17 times compared to the pure drug. Fourier transform infrared spectroscopy (both infrared and X-ray diffraction) revealed no new chemical structure of the tested connections and concluded that there was no interaction between the drug and the polymer in the test diffractions. Solid dispersions with the best parameters were used to prepare hydrogels, and the pharmaceutical availability of clotrimazole was analysed. The best properties were characterized by a hydrogel that was composed of the ratio of the amount of drug to polymer 5:5. The study demonstrated the availability of a pharmaceutical drug release at a therapeutic concentration in the first hour of the study. The use of the appropriate balance between clotrimazole and chitosan and the development of the hydrogel composition may affect the improvement of the drug solubility and may create the possibility of obtaining sustained or controlled release of the drug substance.

14

Analysis of Structural Changes in Starch-Aluminosilicate Binder and Molding Sand with its Participation after Physical Curing

75%

Żymankowska-Kumon S., Grabowska B., Bobrowski A., Kaczmarska K., Cukrowicz S.

Archives of Foundry Engineering

|

2018

|

issue 3

15

USE OF GLUTARIC ACID TO IMPROVE THE SOLUBILITY AND DISSOLUTION PROFILE OF GLIPIZIDE THROUGH PHARMACEUTICAL COCRYSTALLIZATION

75%

Batool F., Ahmad M., Minhas M. U., Khalid Q., Idrees H. A., Khan F. M.

Acta Poloniae Pharmaceutica - Drug Research

|

2019

|

vol. 76

|

issue 1

103-114

EN

The purpose of current study was to improve the solubility and dissolution profile of BCS class-II drug Glipizide using glutaric acid as a coformer via various cocrystalization techniques i.e., dry grinding, liquid assisted grinding, slurry and solvent evaporation. Fourier Transform Infrared Spectroscopy (FTIR) was performed to determine the interaction between components of glipizide-glutaric acid (GPZ-GLU) cocrystals. Powder X-ray Diffraction (PXRD) studies confirmed the crystalline nature of formulated cocrystals. Scanning Electron Microscopy (SEM) revealed cylindrical to rectangular shape of cocrystals. Flow properties of GPZ-GLU cocrystals were evaluated by micromeritics analysis. Size and surface morphology was determined by zeta sizer analysis and optical microscopy. Differential scanning calorimetry (DSC) and Thermogravimetric (TGA) analysis were performed to determine the melting points as well as thermal stability of pure components and formulated GPZ-GLU cocrystals. In-vitro drug release studies were carried out using dissolution apparatus-II. GPZ-GLU cocrystals showed higher drug release at pH 6.8 as compared to pH 1.2. However, percent drug release of optimum formulations at pH 6.8 was determined as; 24%-92.2% (F3) and 12.0%-93.5% (F7). Solubility studies revealed improved solubility as compared to pure drug in water i.e., 53 folds and 54.27 folds from F3 and F7 cocrystals, respectively. Finally it was concluded that glutaric acid has improved the solubility and dissolution profile of glipizide. However, many cocrystal formers have been reported in literature that can be used to enhance the physicochemical properties as well as bioavailability of poorly soluble drugs via cocrystalization technique.

16

Study on the improvement of hydrophilic character on polyvinylalcohol treated polyester fabric

75%

S. P., J. J. M., Natarajan S.

Polish Journal of Chemical Technology

|

2014

|

vol. 16

|

issue 4

21-27

EN

Polyester fabric was treated with polyvinyl alcohol in alkaline medium. The moisture regain, water retention and wettability of the PVA treated polyester fabric were tested. The PVA treated PET fabric was dyed with disperse dye. The presence of PVA in the treated PET fabric was assessed by spot test. The treated fabric was also characterized by scanning electron microscope, FTIR and differential scanning calorimetry. The PVA treated polyester fabric showed improved hydrophilic character over intact and sodium hydroxide treated PET fabrics.

17

The Influence of Technological PVD Process Parameters on the Topography, Crystal and Molecular Structure of Nanocomposite Films Containing Palladium Nanograins

75%

Rymarczyk J., Czerwosz E., Kozłowski M., Dłużewski P., Kowalski W.

Polish Journal of Chemical Technology

|

2014

|

vol. 16

|

issue 3

18-24

EN

The paper describes the preparation and characteristics of films composed of Pd nanograins placed in carbonaceous matrix. Films were obtained in PVD (Physical Vapor Deposition) process from two sources containing: the first one - fullerene powder and the second one - palladium acetate. The topographical, morphological and structural changes due to different parameters of PVD process were studied with the use of Atomic Force Microscopy and Scanning Electron Microscopy, whereas the structure was studied with the application of the Transmission Electron Microscopy and Fourier Transform Infrared Spectroscopy methods. It was shown that topographical changes are connected with the decomposition ratio of Pd acetate as well as the form of carbonaceous matrix formed due to this decomposition. Palladium nanograins found in all films exhibit the fcc structure type and their diameter changes from 2 nm to 40 nm depending on the PVD process parameters.

18

BOX BEHNKEN DESIGN: A STATISTICAL APPROACH TO EVALUATE THE EFFECT OF CROSSLINKED CARBOXYMETHYL CELLULOSE AND SODIUM STARCH GLYCOLATE ON RELEASE KINETICS OF DRUG

75%

Hanif M., Abbas G., Rasul A., Khan S. M., Amir M. N.

Acta Poloniae Pharmaceutica - Drug Research

|

2018

|

vol. 75

|

issue 4

965-975

EN

The aim of study was to evaluate the release kinetics of domperidone maleate (DM) from immediate release (IR) tablets prepared by wet granulation method. Box behnken design (BBD) was used to optimize and evaluate the main, interaction and quadratic effects of independent variables i.e. crosslinked carboxymethyl cellulose (CMC) (X1), sodium starch glycolate (SSG) (X2) and starch (X3) on responses R2 of first order (YI) and β value of weibull model (Y2). Prepared tablets were characterized by various physical tests, in-vitro drug release, fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD) and differential scanning calorimetry (DSC). Accelerated stabilities studies were performed on optimized formulation D9. Y1 and Y2 were ranged from 0.9959 to 0.9994 and 0.041 to 0.912 respectively. β value of weibull model indicated the parabolic shape of dissolution curve. The quadratic model fit the data well and the resulting equations were used to predict the responses in the box behnken design. FTIR spectra showed the compatibility of DM with CMC and SSG. XRD presented diffraction lines indicates crystalline nature of drug. DSC thermograms indicated endothermic peak at 220 0C for DM. Stabilities studies revealed that no significant change in hardness, friability, disintegration time and dissolution release profile of DM. It is concluded that a combination of CMC and SSG can be used to enhance the dissolution and release kinetics of IR tablets of DM.

19

FUNCTIONAL THREE-COMPONENT POLYMERIC BIOCOMPOSITES FOR THE TREATMENT OF BEDSORES

75%

Wiśniewska-Wrona M., El Fray M.

|

vol. 23

185 - 206

EN

Presented here are the results of investigations into the preparation of three-component dressing materials from various biopolymers in the form of a single-layer film which is suitable as a carrier for pain-relieving (lidocaine) and bacteriostatic (sulphanilamid) therapeutic agents. Physical-chemical, biological and usable properties of the prepared materials were tested and assessed. The amount of added active substance was adopted based on the dose recommended by the Polish Pharmacopeia for external medicinal preparations. Antibacterial activity against gram (-) Escherichia coli and gram (+) Staphylococcus aureus was assessed in some of the biocomposites by quantitative methods. The cytotoxic action in direct contact with the mouse fibroblast NCTC clone 929 was also estimated. Thermal analysis (DSC), infrared spectrophotometry (FTIR) and nuclear magnetic resonance spectroscopy were employed to investigate the impact of the variable contents of chitosan, alginate, carboxymethyl cellulose (CMC), and the active substance upon the chemical- and phase-structure of the prepared three-component polymeric biocomposites. It was found that the quantitative composition of the biocomposites and the additive of active substances lidocaine and sulphanilamide exert a vital impact upon their physical-mechanical and usable properties (imbibition, absorption). Investigations into the release of the medicinal substance from the investigated biocomposites to an acceptor fluid led to the conclusion that the kinetics of the process may be described by a complex first order rate equation with two exponential functions.

20

Effect of surface oxidation in air and water on hydrophobicity and floatability of a bituminous coal

75%

Wen B., Xia W., Sokolovic J. M.

Archives of Mining Sciences

|

2019

|

vol. 64

|

issue 1

Refine search results

Synthesis of hydroxyapatite by using calcium carbonate and phosphoric acid in various water-ethanol solvent systems

Methotrexate binding causes structural and functional changes in lung cystatin

The effect of flame coal oxidation on the solid and soluble products of its extraction

Open-Path FTIR Spectral Radiation Intensity Of Hot Combustion Gases – Measurement And Interpretation

A Local Model and Calibration Set Ensemble Strategy for Open-Path FTIR Gas Measurement with Varying Temperature

A Multi-Band Integrated Virtual Calibration-Inversion Method for Open Path FTIR Spectrometry

PHYSICOCHEMICAL CHARACTERIZATION AND DISSOLUTION STUDIES OF SOLID DISPERSIONS OF CLOTRIMAZOLE WITH CHITOSAN

THERMAL DEGRADATION OF DOUBLE CROSSLINKED HYDROGEL CHITOSAN MEMBRANES

Influence of acceptor functionality on charge transfer interactions in mixtures of poly(9-vinylcarbazole) with nitroaromatic compounds

Low temperature synthesis and characterization of Mn3O4 nanoparticles

Studies of the soluble part of oxidised coals

Trace metal, FTIR and phytochemical analysis of Viscum album leaves harvested from Pentaclethra macrophylla

THE INFLUENCE OF A DENTAL FORMULATION PREPARED WITH CHITOSAN ON THE PHARMACEUTICAL AVAILABILITY OF CLOTRIMAZOLE

Analysis of Structural Changes in Starch-Aluminosilicate Binder and Molding Sand with its Participation after Physical Curing

USE OF GLUTARIC ACID TO IMPROVE THE SOLUBILITY AND DISSOLUTION PROFILE OF GLIPIZIDE THROUGH PHARMACEUTICAL COCRYSTALLIZATION

Study on the improvement of hydrophilic character on polyvinylalcohol treated polyester fabric

The Influence of Technological PVD Process Parameters on the Topography, Crystal and Molecular Structure of Nanocomposite Films Containing Palladium Nanograins

BOX BEHNKEN DESIGN: A STATISTICAL APPROACH TO EVALUATE THE EFFECT OF CROSSLINKED CARBOXYMETHYL CELLULOSE AND SODIUM STARCH GLYCOLATE ON RELEASE KINETICS OF DRUG

FUNCTIONAL THREE-COMPONENT POLYMERIC BIOCOMPOSITES FOR THE TREATMENT OF BEDSORES

Effect of surface oxidation in air and water on hydrophobicity and floatability of a bituminous coal