Facile Regeneration Strategy for Facet-Controlled Nanocatalysts via the Dissolution–Reprecipitation Process Promoted by an Organic Modifier

2021 ◽  
Author(s):  
Takaaki Tomai ◽  
Liangyu Tang ◽  
Akira Yoko ◽  
Yuki Omura ◽  
Gimyeong Seong ◽  
...  
Keyword(s):  
Organic Modifier ◽  
Regeneration Strategy

Development of HPLC Method for the Purity Test by Design of Experiments and Determination of Activation Energy of Hydrolytic Degradation Reactions of Sofosbuvir

2020 ◽  
Vol 16 (7) ◽  
pp. 976-987
Author(s):  
Jakub Petřík ◽  
Jakub Heřt ◽  
Pavel Řezanka ◽  
Filip Vymyslický ◽  
Michal Douša
Keyword(s):  
Activation Energy ◽  
Design Of Experiments ◽  
Mobile Phase ◽  
Hydrolytic Degradation ◽  
Isoconversional Method ◽  
Hplc Method ◽  
Organic Modifier ◽  
Calculation Methods ◽  
Degradation Reactions

Background: The present study was focused on the development of HPLC method for purity testing of sofosbuvir by the Design of Experiments and determination of the activation energy of hydrolytic degradation reactions of sofosbuvir using HPLC based on the kinetics of sofosbuvir degradation. Methods: Following four factors for the Design of Experiments were selected, stationary phase, an organic modifier of the mobile phase, column temperature and pH of the mobile phase. These factors were examined in two or three level experimental design using Modde 11.0 (Umetrics) software. The chromatographic parameters like resolution, USP tailing and discrimination factor were calculated and analysed by partial least squares. The chromatography was performed based on Design of Experiments results with the mobile phase containing ammonium phosphate buffer pH 2.5 and methanol as an organic modifier. Separation was achieved using gradient elution on XBridge BEH C8 at 50 °C and a flow rate of 0.8 mL/min. UV detection was performed at 220 nm. The activation energy of hydrolytic degradation reactions of sofosbuvir was evaluated using two different calculation methods. The first method is based on the slope of dependence of natural logarithm of the rate constant on inverted thermodynamic temperature and the second approach is the isoconversional method. Results and Conclusion: Calculated activation energies were 77.9 ± 1.1 kJ/mol for the first method and 79.5 ± 3.2 kJ/mol for the isoconversional method. The results can be considered to be identical, therefore both calculation methods are suitable for the determination of the activation energy of degradation reactions.

scholarly journals Effect of Organic Modifier Types on the Physical–Mechanical Properties and Overall Migration of Post-Consumer Polypropylene/Clay Nanocomposites for Food Packaging

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1502
Author(s):  
Eliezer Velásquez ◽  
Sebastián Espinoza ◽  
Ximena Valenzuela ◽  
Luan Garrido ◽  
María José Galotto ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Food Packaging ◽  
Clay Nanocomposites ◽  
Organic Modifier ◽  
Thermal And Mechanical Properties ◽  
Chemical Safety ◽  
Elongation At Break ◽  
Fatty Food ◽  
Recycled Plastics ◽  
Thermal Stability Of

The deterioration of the physical–mechanical properties and loss of the chemical safety of plastics after consumption are topics of concern for food packaging applications. Incorporating nanoclays is an alternative to improve the performance of recycled plastics. However, properties and overall migration from polymer/clay nanocomposites to food require to be evaluated case-by-case. This work aimed to investigate the effect of organic modifier types of clays on the structural, thermal and mechanical properties and the overall migration of nanocomposites based on 50/50 virgin and recycled post-consumer polypropylene blend (VPP/RPP) and organoclays for food packaging applications. The clay with the most hydrophobic organic modifier caused higher thermal stability of the nanocomposites and greater intercalation of polypropylene between clay mineral layers but increased the overall migration to a fatty food simulant. This migration value was higher from the 50/50 VPP/RPP film than from VPP. Nonetheless, clays reduced the migration and even more when the clay had greater hydrophilicity because of lower interactions between the nanocomposite and the fatty simulant. Conversely, nanocomposites and VPP/RPP control films exhibited low migration values in the acid and non-acid food simulants. Regarding tensile parameters, elongation at break values of PP film significantly increased with RPP addition, but the incorporation of organoclays reduced its ductility to values closer to the VPP.

scholarly journals Applicability of a Monolithic Column for Separation of Isoquinoline Alkalodis from Chelidonium majus Extract

Molecules ◽  
2019 ◽  
Vol 24 (19) ◽  
pp. 3612 ◽  
Author(s):  
Staniak ◽  
Wójciak-Kosior ◽  
Sowa ◽  
Strzemski ◽  
Sawicki ◽  
...  
Keyword(s):  
Monolithic Column ◽  
Gradient Elution ◽  
Root Extract ◽  
Organic Modifier ◽  
Isoquinoline Alkaloids ◽  
Chelidonium Majus ◽  
Peak Asymmetry ◽  
Application Potential ◽  
Chromatographic Plate ◽  
Chromatographic Parameters

Isoquinoline alkaloids are the main group of secondary metabolites present in Chelidonium majus extracts, and they are still the object of interest of many researchers. Therefore, the development of methods for the investigation and separation of the alkaloids is still an important task. In this work, the application potential of a silica-based monolithic column for the separation of alkaloids was assessed. The influence of the organic modifier, temperature, salt concentration, and pH of the eluent on basic chromatographic parameters such as retention, resolution between neighboring peaks, chromatographic plate numbers, and peak asymmetry were investigated. Based on the obtained results, a gradient elution program was developed and used to separate and quantitatively determine the main alkaloids in a Chelidonium majus root extract.

NiMo/alumina hydrodesulphurization catalyst modified by saccharose: Effect of addition stage of organic modifier

2015 ◽  
Vol 94 (1) ◽  
pp. 66-74 ◽  
Author(s):  
José Escobar ◽  
Ana W. Gutiérrez ◽  
María C. Barrera ◽  
José A. Colín
Keyword(s):  
Organic Modifier

Influence of clay organic modifier on the thermal-stability of PLA based nanocomposites

2014 ◽  
Vol 88-89 ◽  
pp. 144-150 ◽  
Author(s):  
A. Araújo ◽  
G. Botelho ◽  
M. Oliveira ◽  
A.V. Machado
Keyword(s):  
Thermal Stability ◽  
Organic Modifier ◽  
Thermal Stability Of

scholarly journals Gradient HPLC in the determination of drug lipophilicity and acidity

2001 ◽  
Vol 73 (9) ◽  
pp. 1465-1475 ◽  
Author(s):  
Roman Kaliszan ◽  
Piotr Haber ◽  
Tomasz Baczek ◽  
Danuta Siluk
Keyword(s):  
Mobile Phase ◽  
High Performance ◽  
Standard Procedure ◽  
Gradient Elution ◽  
Log P ◽  
Retention Data ◽  
Organic Modifier ◽  
Wide Range ◽  
Aqueous Component ◽  
Initial Ph

The linear-solvent strength (LSS) model of gradient elution in high-performance liquid chromatography (HPLC) has been demonstrated to provide parameters of lipophilicity and acidity of analytes. pKa and log kw values are determined in three gradient runs. The first two experiments use an aqueous buffered eluent with a wide-range organic modifier gradient at pH of buffer, providing suppression of ionization of the analyte. That experiment allows an estimate of contents of the organic modifier in the mobile phase (%B), producing requested retention coefficient, k, for the nonionized form of the analyte. The next experiment is carried out with the latter %B and a pH-gradient of the aqueous component of the eluent that is sufficient to overlap possible pKa value of the analyte. The initial pH of the buffer used to make the mobile phase is selected to insure that the analyte is in nonionized form. The resulting retention time allows an estimate of pKa in a solvent of the given %B.The log kw parameter obtained correlated well with the corresponding value obtained by the standard procedure of extrapolation of retention data determined in a series of isocratic measurements. The correlation between log kw and the reference parameter of lipophilicity, log P, was very good for a series of test analytes. The values of pKa were found to correlate with the literature pKa data determined in water for a set of aniline derivatives studied.

scholarly journals Stem Cell-Engineered Nanovesicles Exert Proangiogenic and Neuroprotective Effects

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1078
Author(s):  
Han Young Kim ◽  
Suk Ho Bhang
Keyword(s):  
Stem Cells ◽  
Endothelial Cells ◽  
Mesenchymal Stem Cells ◽  
Tissue Regeneration ◽  
Therapeutic Agent ◽  
Therapeutic Effects ◽  
Hydrodynamic Size ◽  
Regeneration Strategy ◽  
Neuroprotective Effects ◽  
The Poor

As a tissue regeneration strategy, the utilization of mesenchymal stem cells (MSCs) has drawn considerable attention. Comprehensive research using MSCs has led to significant preclinical or clinical outcomes; however, improving the survival rate, engraftment efficacy, and immunogenicity of implanted MSCs remains challenging. Although MSC-derived exosomes were recently introduced and reported to have great potential to replace conventional MSC-based therapeutics, the poor production yield and heterogeneity of exosomes are critical hurdles for their further applications. Herein, we report the fabrication of exosome-mimetic MSC-engineered nanovesicles (MSC-NVs) by subjecting cells to serial extrusion through filters. The fabricated MSC-NVs exhibit a hydrodynamic size of ~120 nm, which is considerably smaller than the size of MSCs (~30 μm). MSC-NVs contain both MSC markers and exosome markers. Importantly, various therapeutic growth factors originating from parent MSCs are encapsulated in the MSC-NVs. The MSC-NVs exerted various therapeutic effects comparable to those of MSCs. They also significantly induced the angiogenesis of endothelial cells and showed neuroprotective effects in damaged neuronal cells. The results collectively demonstrate that the fabricated MSC-NVs can serve as a nanosized therapeutic agent for tissue regeneration.

Sign in / Sign up

Export Citation Format

Share Document