scholarly journals Immobilization of Phospholipase A1 Using a Protein-Inorganic Hybrid System

Polymers ◽  
2021 ◽  
Vol 13 (17) ◽  
pp. 2865
Author(s):  
Shi Cheng ◽  
Zitao Guo ◽  
Chaojuan Liang ◽  
Yi Shi ◽  
Peng Geng ◽  
...  
Keyword(s):  
Immobilized Enzymes ◽  
Temperature Tolerance ◽  
Relative Activity ◽  
Free Enzyme ◽  
Hybrid Nanostructures ◽  
X Ray Diffraction ◽  
Phospholipase A1 ◽  
Scanning Calorimetry ◽  
The Stability ◽  
Hybrid Complexes

In this study, four kinds of phospholipase A1-metal (Al/Co/Cu/Mn) hybrid nanostructures were prepared for enhancing the stability of the free PLA1. The formed hybrid complexes were characterized by scanning electron microscope (SEM), Fourier infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The stability and substrate specificity of immobilized enzymes were subsequently determined. After immobilization, the temperature tolerance of PLA1–metal hybrid nanostructures was enhanced. The relative activity of PLA1–Al/Co/Cu hybrid nanostructures remained above 60% at 50 °C, while that of free enzyme was below 5%. The thermal transition temperature measured by differential scanning calorimetry (DSC) was found to increase from 65.59 °C (free enzyme) to 173.14 °C, 123.67 °C, 96.31 °C, and 114.79 °C, referring to PLA1–Cu/Co/Al/Mn hybrid nanostructures, respectively. Additionally, after a storage for fourteen days at 4 °C, the immobilized enzymes could exhibit approximately 60% of the initial activity, while the free PLA1 was inactivated after four days of storage. In brief, using Co2+, Cu2+, Al3+, and Mn2+ as the hybridization materials for immobilization could improve the catalytic properties and stability of the free PLA1, suggesting a promising method for a wider application of PLA1 in many fields such as food, cosmetics, and the pharmaceutical industry.

scholarly journals A simultaneous X-ray diffraction–differential scanning calorimetry study into the phase transitions of mefenamic acid

2019 ◽  
Vol 52 (6) ◽  
pp. 1264-1270 ◽  
Author(s):  
Yuying Pang ◽  
Asma Buanz ◽  
Richard Telford ◽  
Oxana V. Magdysyuk ◽  
Simon Gaisford ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Mefenamic Acid ◽  
Cell Expansion ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Differential Scanning Calorimetry Study ◽  
Polymorphic Transitions ◽  
X Ray ◽  
New Form ◽  
The Stability

In this study, the polymorphic transitions of mefenamic acid (MA) were studied by synchrotron X-ray powder diffraction combined with differential scanning calorimetry (XRD-DSC). The initial material was found to be phase-pure form I which, when heated, produces two endotherms that can be observed by DSC at 162.72 and 219.55°C. The former was found to correspond to a solid–solid enantiotropic transition from form I to a mixture of forms II and III. The latter is the melting point of form II. As form I is heated, significantly greater unit-cell expansion is seen in the a direction than in b and c, which can be explained by the stronger intermolecular interactions in the bc plane. Refinements of the reported MA structures against the patterns collected during heating revealed that at 175°C there exists a mixture of forms I, II and III, whereas only forms II and III remain at 205°C. However, reflections are observed at both temperatures which cannot be fitted with the known forms of MA. It is hypothesized that a new form of MA is produced upon heating. The stability of MA after the enantiotropic transition temperature is II > III > I, which differs from the previously reported II > I > III.

scholarly journals Crystallization Process and Microstructural Evolution of Melt Spun Al-RE-Ni-(Cu) Ribbons

Metals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 443
Author(s):  
Francisco G. Cuevas ◽  
Sergio Lozano-Perez ◽  
Rosa María Aranda ◽  
Raquel Astacio
Keyword(s):  
Crystallization Process ◽  
Primary Crystallization ◽  
Amorphous Structure ◽  
Intermetallic Phases ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
Melt Spun ◽  
The Stability

The crystallization process, both at the initial and subsequent stages, of amorphous Al88-RE4-Ni8 alloys (RE = Y, Sm and Ce) has been studied. Additionally, the consequences of adding 1 at.% Cu replacing Ni or Al were studied. The stability of the amorphous structure in melt spun ribbons was thermally studied by differential scanning calorimetry, with Ce alloys being the most stable. The effect of Cu to reduce the nanocrystal size during primary crystallization was analyzed by transmission electron microscopy. This latter technique and x-ray diffraction showed the formation of intermetallic phases at higher temperatures. A clear difference was observed for the Ce alloy, with a simpler sequence involving the presence of Al3Ni and Al11Ce3. However, for the Y and Sm alloys, a more complex evolution involving metastable ternary phases before Al19RE5Ni3 appears, takes place. The shape of the intermetallics changes from equiaxial in the Ce alloys to elongate for Y and Sm, with longer particles for Sm and, in general, when Cu is added to the alloy.

Preparation and Characterization of Tea Polyphenols/Starch Inclusion Complex

2013 ◽  
Vol 432 ◽  
pp. 413-417 ◽  
Author(s):  
Li Ming Zhang ◽  
Zhi Ying Hu ◽  
Li Hu Yan ◽  
Run Liu Li ◽  
Cheng Wei Cao ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Inclusion Complex ◽  
Inclusion Complexes ◽  
Tea Polyphenols ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
The Stability ◽  
Good Retention

In order to improving the stability and bioavailability of tea polyphenols (TP), the TP/starchinclusion complex(TPSIC) was prepared by adding TP to starch slurry during gelatinization, and its TPreleasing behaviorswas investigated. The formation of inclusion complex was confirmed by powder X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The TPSIC showed a characteristic of V-type crystallinity and a looser gel matrix. The encapsulation increased the stability of TP and generated a good releasing behavior after enzymatic erosion. The lower releasing rate indicated that the prepared inclusion complexes had good retention ability and effectively reduced the releasing rate of TP. The releasing rate of TPSIC increased with the increase of TP concentration.

X-ray powder diffraction study of Sn0.59Ti0.41Te3O8

2008 ◽  
Vol 23 (3) ◽  
pp. 228-231 ◽  
Author(s):  
W. Ben Aribia ◽  
M. Loukil ◽  
A. Kabadou ◽  
A. Ben Salah
Keyword(s):  
Powder Diffraction ◽  
Room Temperature ◽  
Structural Information ◽  
Lone Pair ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
The Stability ◽  
Ir Spectroscopic

The crystal structure of titanium-tin tellurium oxide Sn0.59Ti0.41Te3O8 has been determined using X-ray powder diffraction techniques. At room temperature, the title compound crystallizes in cubic space group Ia-3, with lattice parameter a=11.05515(6) Å. Rietveld refinement of the structure led to final confidence factors Rp=0.0395 and Rwp=0.0577. The structure of Sn0.59Ti0.41Te3O8 consists of isolated Ti/SnO6-octahedra slightly deformed in the a direction. The TeO4E [E=lone pair of Te(IV) atoms] groups are located between the octahedra ensuring the stability of the structure by Ti/Sn-O-Te bonding contacts. Only one peak in thermal behavior was detected for this compound at 488 K by differential scanning calorimetry experiment. An IR spectroscopic study is employed as a means to obtain preliminary structural information and shows the presence of the Ti/SnO6 and TeO4E groups. This result is later confirmed by X-ray diffraction studies.

scholarly journals Influence of film stretching on crystalline phases and dielectric properties of a 70/30 mol% poly(vinylidenefluoride-tetrafluoroethylene) copolymer

2020 ◽  
Vol 10 (05) ◽  
pp. 2050023
Author(s):  
Thulasinath Raman Venkatesan ◽  
Anna A. Gulyakova ◽  
Reimund Gerhard
Keyword(s):  
Dielectric Properties ◽  
Polyvinylidene Fluoride ◽  
Ferroelectric Phase ◽  
Mechanical Analysis ◽  
Dielectric Relaxation Spectroscopy ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Crystalline Phases ◽  
The Stability ◽  
Dissipation Losses

Polyvinylidene fluoride (PVDF)-based copolymers with tetrafluoroethylene (P(VDF-TFE)), trifluoroethylene (P(VDF-TrFE)) or hexafluoropropylene (P(VDF-HFP)) are of strong interest due to the underlying fundamental mechanisms and the potential ferro-, pyro- and piezo-electrical applications. Their flexibility and their adaptability to various shapes are advantageous in comparison to inorganic ferroelectrics. Here, we study the influence of stretching temperature on the crystalline phases and the dielectric properties in P(VDF-TFE) films by means of Dielectric Relaxation Spectroscopy (DRS), Fourier-Transform InfraRed spectroscopy (FTIR), Wide-Angle X-ray Diffraction (WAXD), Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA). Especially, the effect of stretching and the influence of the temperature of stretching on the mid-temperature ([Formula: see text] transition are studied in detail. The results show that stretching has a similar effect as that on PVDF, and we observe an increase in the fraction of ferroelectric [Formula: see text]-phase with a simultaneous increment in both melting point ([Formula: see text] and crystallinity ([Formula: see text] of the copolymer. While an increase in the stretching temperature does not have a profound impact on the amount of ferroelectric phase, the stability of the ferroelectric phase seems to improve — as seen in the reduction of the Full Width at Half Maximum (FWHM) of the WAXD peaks in both parallel and perpendicular directions to the molecular chain axis. The observation is also supported by the reduction of dissipation losses with an increase in stretching temperature — as seen in DRS measurements. Finally, both stretching itself and the temperature of stretching affect the various molecular processes taking place in the temperature range of the [Formula: see text] transition.

scholarly journals Reversible De-/Rehydration Process in Paroxetine Hydrobromide

2014 ◽  
Vol 70 (a1) ◽  
pp. C999-C999
Author(s):  
Paulo Carvalho-Jr ◽  
Javier Ellena ◽  
Alejandro Ayala
Keyword(s):  
Crystal Structure ◽  
Crystal Packing ◽  
Pharmaceutical Formulations ◽  
Ambient Atmosphere ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
The Stability ◽  
Dehydration Behavior ◽  
Rehydration Process

Paroxetine (PRX) is an antidepressant widely used in depression treatment for decades. The anhydrous and hemidrate chloride forms have been used in pharmaceutical formulations. During their developing a discussion associated with its physical forms and the complex hydration/dehydration behavior involving these phases were established. To improve our understanding of this issue we investigate the crystal structure of paroxetine bromide hemidrate, (PRX+.Br-).H2O, as a model for understanding the stability anhydrous/hemihydrate paroxetine arrangements and the nature of the intermolecular interaction of water within the crystal lattice by single crystal X-ray diffraction experiments. A combination of complementary characterization techniques were also used including Differential Scanning Calorimetry (DSC), thermogravimetric analysis (TGA), Hot Stage microscopy and solubility measurements. As expected the paroxetine bromide hemidrate, (PRX+.Br-).H2O, is isostructural with the paroxetine chloride hemidrate, (PRX+.Cl-).H2O. As in that case, the crystal packing of (PRX+.Br-).H2O is stabilized by strong NH2+...O and NH2+...Br hydrogen bonds which forms infinite channels along the b axis. The water and bromide anions are located along these channels. The DSC/TGA analysis for (PRX+.Br-).H2O show an endothermic desolvation process with an onset temperature of 77.09 °C, that is not present in the paroxetine chloride hemidrate DSC curve. This process leaves to a paroxetine anhydrous bromide crystal structure that is isomorphic to the anhydrous chloride one. However, this structure is spontaneously rehydrated at ambient atmosphere. This rehydration phenomenon probe the stability of paroxetine hemihydrate arrangement, since (PRX+.Br-) is slightly more soluble that its hydrate form. As opposed to chloride hemidrate, the rehydration of paroxetine bromide only involves a rearrangement of the water molecule within the cavities.

Influence of Al on Quasicrystal Formation in Zr-Ti-Nb-Cu-Ni-Al Metallic Glasses

2003 ◽  
Vol 805 ◽  
Author(s):  
Sergio Scudino ◽  
Jürgen Eckert ◽  
Uta Kühn ◽  
Hergen Breitzke ◽  
Klaus Lüders ◽  
...  
Keyword(s):  
Supercooled Liquid ◽  
Supercooled Liquid Region ◽  
Quasicrystalline Phase ◽  
Liquid Region ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Al Content ◽  
Transmission Electron ◽  
The Stability ◽  
Thermal Stability Of

ABSTRACTThe effect of Al on the crystallization behavior of (Zr0.616Ti0.087Nb0.027Cu0.15Ni0.12)100–xAlx melt-spun glassy ribbons with x = 7.5, 5, 2.5 and 0 was investigated by differential scanning calorimetry, x-ray diffraction and transmission electron microscopy. The devitrification of the ribbons is characterized by the formation of a metastable quasicrystalline phase during the first stage of the crystallization process even for the alloy with x = 0. Therefore, Al is not essential for quasicrystal formation in the present alloys. However, it affects the properties of the amorphous as well as of the quasicrystalline phase. With decreasing Al content, the temperature range of stability of the quasicrystalline phase increases whereas the thermal stability of the amorphous phase decreases together with a slight decrease of the extension of the supercooled liquid region. Thus, it is concluded that although the addition of Al improves the stability of the glassy phase, it has no beneficial effect on the formation of quasicrystals.

Influence of Al on Quasicrystal Formation in Zr-Ti-Nb-Cu-Ni-Al Metallic Glasses

2003 ◽  
Vol 806 ◽  
Author(s):  
Sergio Scudino ◽  
Jürgen Eckert ◽  
Uta Kühn ◽  
Hergen Breitzke ◽  
Klaus Lüders ◽  
...  
Keyword(s):  
Supercooled Liquid ◽  
Supercooled Liquid Region ◽  
Quasicrystalline Phase ◽  
Liquid Region ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Al Content ◽  
Transmission Electron ◽  
The Stability ◽  
Thermal Stability Of

ABSTRACTThe effect of Al on the crystallization behavior of (Zr0.616Ti0.087 Nb0.027Cu0.15Ni0.12)100−xAlx melt-spun glassy ribbons with x = 7.5, 5, 2.5 and 0 was investigated by differential scanning calorimetry, x-ray diffraction and transmission electron microscopy. The devitrification of the ribbons is characterized by the formation of a metastable quasicrystalline phase during the first stage of the crystallization process even for the alloy with x = 0. Therefore, Al is not essential for quasicrystal formation in the present alloys. However, it affects the properties of the amorphous as well as of the quasicrystalline phase. With decreasing Al content, the temperature range of stability of the quasicrystalline phase increases whereas the thermal stability of the amorphous phase decreases together with a slight decrease of the extension of the supercooled liquid region. Thus, it is concluded that although the addition of Al improves the stability of the glassy phase, it has no beneficial effect on the formation of quasicrystals.

Fractionation of polymethylene chains: An electron crystallographic investigation

1986 ◽  
Vol 44 ◽  
pp. 794-795
Author(s):  
Douglas L. Dorset
Keyword(s):  
Cross Section ◽  
Binary Systems ◽  
Linear Chain ◽  
Pure Component ◽  
Organic Substrates ◽  
Crystallographic Investigation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Molecular Sizes ◽  
The Stability

A variety of linear chain materials exist as polydisperse systems which are difficultly purified. The stability of continuous binary solid solutions assume that the Gibbs free energy of the solution is lower than that of either crystal component, a condition which includes such factors as relative molecular sizes and shapes and perhaps the symmetry of the pure component crystal structures.Although extensive studies of n-alkane miscibility have been carried out via powder X-ray diffraction of bulk samples we have begun to examine binary systems as single crystals, taking advantage of the well-known enhanced scattering cross section of matter for electrons and also the favorable projection of a paraffin crystal structure posited by epitaxial crystallization of such samples on organic substrates such as benzoic acid.

Glibenclamide-Nicotinamide Cocrystals Synthesized by The Solvent Evaporation Method to Enhance Solubility and Dissolution Rate of Glibenclamide

2019 ◽  
Vol 9 (01) ◽  
pp. 21-26
Author(s):  
Arif Budiman ◽  
Ayu Apriliani ◽  
Tazyinul Qoriah ◽  
Sandra Megantara
Keyword(s):  
Solvent Evaporation ◽  
Physical Mixture ◽  
Dissolution Profile ◽  
Solvent Evaporation Method ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Evaporation Method ◽  
Dissolution Properties ◽  
Mixture Characterization

Purpose: To develop glibenclamide-nicotinamide cocrystals with the solvent evaporation method and evaluate their solubility and dissolution properties. Methods: Cocrystals of glibenclamide-nicotinamide (1:2) were prepared with the solvent evaporation method. The prediction of interactive cocrystals was observed using in silico method. The solubility and dissolution were performed as evaluation of cocrystals. The cocrystals also were characterized by differential scanning calorimetry (DSC), infrared spectrophotometry, and powder X-ray diffraction (PXRD). Result: The solubility and dissolution profile of glibenclamide-nicotinamide cocrystal (1:2) increased significantly compared to pure glibenclamide as well as its physical mixture. Characterization of cocrystal glibenclamide-nicotinamide (1:2) including infrared Fourier transform, DSC, and PXRD, indicated the formation of a new solid crystal phase differing from glibenclamide and nicotinamide. Conclusion: The confirmation of cocrystal glibenclamide-nicotinamide (1:2) indicated the formation of new solid crystalline phases that differ from pure glibenclamide and its physical mixture

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