Effect of Cryogrinding on Physico-Chemical Properties of Drugs. I. Theophylline: Evaluation of Particles Sizes and the Degree of Crystallinity, Relation to Dissolution Parameters

Comprehensive studies of the structural, molecular and physico-chemical properties of cellulose nitrates from hemp fiber were carried out using modern research methods: capillary viscometry, IR Fourier spectroscopy, X-ray diffraction, gel permeation chromatography. The results of the study revealed features of the influence of inter- and intramolecular interactions in cellulose macromolecules from various types of fiber, the degree of crystallinity of the initial material, and the degree of polydispersity on the formation of qualitative characteristics of hemp cellulose nitrates.

Download Full-text

Effect of Carbonate to Phosphate Molar Ratios on the Physico-Chemical Properties of Carbonated Hydroxyapatite Nanopowder

Journal of Engineering Science ◽

10.21315/jes2020.16.2.5 ◽

2020 ◽

Vol 16 (2) ◽

pp. 101-110

Author(s):

Muhammad Syazwan Mohd Noor ◽

Nur Nabilah Afja Mohd Afandi ◽

Ahmad-Fauzi Mohd Noor ◽

Yanny Marliana Baba Ismail

Keyword(s):

Crystal Structure ◽

Single Phase ◽

Chemical Properties ◽

Degree Of Crystallinity ◽

Apatite Structure ◽

Carbonated Hydroxyapatite ◽

Cell Parameters ◽

Molar Ratios ◽

Physico Chemical ◽

The Degree Of Crystallinity

The aim of this study was to incorporate carbonate ions (CO3 2–) into the hydroxyapatite (HA) crystal structure followed by investigation on the effect of different carbonate to phosphate (CO3 2–/PO4 3–) ratios on the phase purity, crystal structure as well as CO3 2– content present in the apatite structure. CO3 2– substitution has been proposed to enhance the performance of HA-based material, particularly on the physico-chemical properties. Three different compositions of carbonated hydroxyapatite (CHA) powder with different CO3 2–/ PO4 3– ratios (namely, CHA 1:1, CHA 2:1 and CHA 4:1) were chemically synthesised by nanoemulsion method at 37°C and characterised for their physico-chemical properties. Results demonstrated that all as-synthesised powders formed single phase B-type CHA without any additional phases. Interestingly, an increasing amount of CO3 2– substituted into the apatite structure gives rise to the formation of CHA structure with a variation on their cell parameters and the degree of crystallinity. An increase in the CO3 2–/ PO4 3– ratio was also found to lead a higher amount of CO3 2– content present in the as-synthesised powder (in a range of 4 wt % to 10 wt %), which is comparable to the CO3 2– content found in the human bone mineral.

Download Full-text

Tailored Biodegradable and Electroactive Poly(Hydroxybutyrate-Co-Hydroxyvalerate) Based Morphologies for Tissue Engineering Applications

International Journal of Molecular Sciences ◽

10.3390/ijms19082149 ◽

2018 ◽

Vol 19 (8) ◽

pp. 2149 ◽

Cited By ~ 7

Author(s):

Luís Amaro ◽

Daniela Correia ◽

Teresa Marques-Almeida ◽

Pedro Martins ◽

Leyre Pérez ◽

...

Keyword(s):

Tissue Engineering ◽

Cobalt Ferrite ◽

Degree Of Crystallinity ◽

Engineering Applications ◽

Cell Proliferation And Differentiation ◽

Cobalt Ferrites ◽

Physico Chemical ◽

Proliferation And Differentiation ◽

The Degree Of Crystallinity ◽

Composite Samples

Polymer-based piezoelectric biomaterials have already proven their relevance for tissue engineering applications. Furthermore, the morphology of the scaffolds plays also an important role in cell proliferation and differentiation. The present work reports on poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV), a biocompatible, biodegradable, and piezoelectric biopolymer that has been processed in different morphologies, including films, fibers, microspheres, and 3D scaffolds. The corresponding magnetically active PHBV-based composites were also produced. The effect of the morphology on physico-chemical, thermal, magnetic, and mechanical properties of pristine and composite samples was evaluated, as well as their cytotoxicity. It was observed that the morphology does not strongly affect the properties of the pristine samples but the introduction of cobalt ferrites induces changes in the degree of crystallinity that could affect the applicability of prepared biomaterials. Young’s modulus is dependent of the morphology and also increases with the addition of cobalt ferrites. Both pristine and PHBV/cobalt ferrite composite samples are not cytotoxic, indicating their suitability for tissue engineering applications.

Download Full-text

Tailored Biodegradable and Electroactive Poly(hydroxybutyrate-co-hydroxyvalerate) Based Morphologies for Tissue Engineering Applications

10.20944/preprints201807.0021.v1 ◽

2018 ◽

Author(s):

Luís Amaro ◽

Daniela M. Correia ◽

Teresa Marques-Almeida ◽

Pedro M. Martins ◽

Leyre Pérez ◽

...

Keyword(s):

Tissue Engineering ◽

Young Modulus ◽

Degree Of Crystallinity ◽

Engineering Applications ◽

Cell Proliferation And Differentiation ◽

Cobalt Ferrites ◽

Physico Chemical ◽

Proliferation And Differentiation ◽

The Degree Of Crystallinity ◽

Composite Samples

Polymer-based piezoelectric biomaterials have already proven their relevance for tissue engineering applications. Further, the morphology of the scaffolds plays also an important role in cell proliferation and differentiation. The present work reports on poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV), a biocompatible, biodegradable and piezoelectric biopolymer that has been processed in different morphologies, including films, fibres, microspheres and 3D scaffolds. Further, the corresponding magnetically active PHBV-based composites were also produced. The effect of the morphology on physico-chemical, thermal, magnetic and mechanical properties of pristine and composites samples was evaluated, as well as their cytotoxicity. It was observed that the morphology does not strongly affect the properties of the pristine samples but the introduction of cobalt ferrites induces changes in the degree of crystallinity that could affect the applicability of prepared biomaterials. Young modulus is dependent of the morphology and also increases with the addition of cobalt ferrites. Both, pristine and PHBV/cobalt ferrite composite samples are no cytotoxic, indicating their suitability for tissue engineering applications.

Download Full-text

Synthesis of Ni(II), Cu (II) and Zn(II) coumarin-3-carboxilic acid derivates and their and their physical-chemical properties

Research Society and Development ◽

10.33448/rsd-v10i3.13430 ◽

2021 ◽

Vol 10 (3) ◽

pp. e47910313430

Author(s):

Dirceu Aparecido Gonçalves de Souza ◽

Ricardo Luis Tranquilin ◽

Marcio Luiz dos Santos ◽

Regina Mara Silva Pereira

Keyword(s):

Metal Ion ◽

Chemical Properties ◽

Biological Properties ◽

New Drugs ◽

Degree Of Crystallinity ◽

X Ray Diffraction ◽

X Ray ◽

Dpph Method ◽

The Degree Of Crystallinity ◽

Transition Complexes

In the search for new drugs, coumarins are an important class of compounds due to their chemical and biological properties, such as their potential to reduce cancer, diabetes, and cardiovascular diseases. They are heterocyclic compounds that contain oxygen in their structure and are found in plants.To improve the chemical and biological properties of the coumarin-3-carboxilic acid, were prepared metal transition complexes of Cu(II), Ni(II) and Zn(II) of coumarin-3-carboxilic acid by a new synthetic route. All complexes were characterized by ultraviolet, Infrared (FTIR), and Raman spectroscopy; Scanning electronic microscopy (SEM); X-Ray diffraction (XRD), as well as conductivity and elemental analysis. Electron microscopy and X-ray analysis showed that the degree of crystallinity of the complexes changes when compared with the precursor, 3-carboxy-coumarin acid, and the degree of crystallinity depends on the nature of the metal ion attached to coumarin. In addition, the antioxidant action of the complexes was evaluated by the DPPH method, and the results showed a higher activity of the complexes when compared with the precursor, suggesting that these complexes may present biological properties of interest.

Download Full-text

Decoration of specific sites on freeze-fractured membranes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100081565 ◽

1978 ◽

Vol 36 (2) ◽

pp. 140-141

Author(s):

H. Gross ◽

H. Moor

Keyword(s):

Pure Water ◽

Freeze Fracture ◽

Chemical Properties ◽

Surface Forces ◽

Sulfate Pentahydrate ◽

Copper Sulfate Pentahydrate ◽

Physico Chemical ◽

Water Of Hydration ◽

Small Container ◽

Binding Forces

Fracturing under ultrahigh vacuum (UHV, p ≤ 10-9 Torr) produces membrane fracture faces devoid of contamination. Such clean surfaces are a prerequisite foe studies of interactions between condensing molecules is possible and surface forces are unequally distributed, the condensate will accumulate at places with high binding forces; crystallites will arise which may be useful a probes for surface sites with specific physico-chemical properties. Specific “decoration” with crystallites can be achieved nby exposing membrane fracture faces to water vopour. A device was developed which enables the production of pure water vapour and the controlled variation of its partial pressure in an UHV freeze-fracture apparatus (Fig.1a). Under vaccum (≤ 10-3 Torr), small container filled with copper-sulfate-pentahydrate is heated with a heating coil, with the temperature controlled by means of a thermocouple. The water of hydration thereby released enters a storage vessel.

Download Full-text

PHYSICO CHEMICAL PROPERTIES OF NICKEL OXIDE AT HIGH TEMPERATURE

Le Journal de Physique Colloques ◽

10.1051/jphyscol:1976798 ◽

1976 ◽

Vol 37 (C7) ◽

pp. C7-438-C7-442 ◽

Cited By ~ 2

Author(s):

R. FARHI ◽

G. PETOT-ERVAS

Keyword(s):

High Temperature ◽

Nickel Oxide ◽

Chemical Properties ◽

Physico Chemical

Download Full-text

Physico-Chemical Properties of Recombinant Desulphatohirudin

Thrombosis and Haemostasis ◽

10.1055/s-0038-1645073 ◽

1990 ◽

Vol 63 (03) ◽

pp. 499-504 ◽

Cited By ~ 4

Author(s):

A Electricwala ◽

L Irons ◽

R Wait ◽

R J G Carr ◽

R J Ling ◽

...

Keyword(s):

Molecular Weight ◽

Gel Filtration ◽

Chemical Properties ◽

Alpha Helix ◽

Apparent Molecular Weight ◽

Correlation Spectroscopy ◽

Nmr Studies ◽

Recombinant Hirudin ◽

Physico Chemical ◽

Recombinant Molecule

SummaryPhysico-chemical properties of recombinant desulphatohirudin expressed in yeast (CIBA GEIGY code No. CGP 39393) were reinvestigated. As previously reported for natural hirudin, the recombinant molecule exhibited abnormal behaviour by gel filtration with an apparent molecular weight greater than that based on the primary structure. However, molecular weight estimation by SDS gel electrophoresis, FAB-mass spectrometry and Photon Correlation Spectroscopy were in agreement with the theoretical molecular weight, with little suggestion of dimer or aggregate formation. Circular dichroism studies of the recombinant molecule show similar spectra at different pH values but are markedly different from that reported by Konno et al. (13) for a natural hirudin-variant. Our CD studies indicate the presence of about 60% beta sheet and the absence of alpha helix in the secondary structure of recombinant hirudin, in agreement with the conformation determined by NMR studies (17)

Download Full-text