scholarly journals Physicochemical characterization of mesquite flours

2018 ◽  
Author(s):  
S. Sandoval Torres ◽  
L. Reyes López ◽  
L. Méndez Lagunas ◽  
J. Rodríguez Ramírez ◽  
G. Barriada Bernal
Keyword(s):  
Thermal Stability ◽  
Particle Size ◽  
Physicochemical Characterization ◽  
Chemical Properties ◽  
Sorption Isotherms ◽  
Nutritional Composition ◽  
Gluten Free ◽  
Sieving Process ◽  
Thermal Stability Of

Ethnic foods are healthy products interesting for the new societies. Mesquite flour offers another option for making gluten-free recipes as part of a diet for people with celiac disease. The physicochemical properties of mesquite flours (Prosopis laevigata) were characterized. The mesquite pods were dried at 60°C, 15% RH and 2 m/s airflow; then a grinding and sieving process were applied. The nutritional composition and the sorption isotherms were obtained at 30, 35, 40 and 45°C  for  water activities of 0.07-0.9. The particle-size distribution, morphology and thermal stability of the flours were determined by different methods. Keywords: Mesquite Flours; drying; isotherms; chemical properties; morphology

Structure and thermal stability of sodium and carbonate-co-substituted strontium hydroxyfluorapatites

2018 ◽  
Vol 42 (11) ◽  
pp. 8469-8477 ◽  
Author(s):  
Mustapha Hidouri ◽  
Sergey V. Dorozhkin
Keyword(s):  
Thermal Stability ◽  
Physicochemical Characterization ◽  
Thermal Stability Of

Physicochemical characterization of sodium and carbonate co-substituted strontium hydroxyfluorapatite resulting in pure apatite with ionic vacancies as a biomaterial.

scholarly journals Preparation and characterization of nanocellulose from sugarcane bagasse

2020 ◽  
Vol 10 (3) ◽  
pp. 5675-5678
Keyword(s):  
Thermal Stability ◽  
Particle Size ◽  
Acid Hydrolysis ◽  
Sugarcane Bagasse ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
Hydrolysis Time ◽  
Chemical Treatments ◽  
Thermal Stability Of

Nanocellulose (NC) was extracted from sugarcane bagasse (SCB) by acid hydrolysis. Alkalization and bleaching were used to treat SCB before the acid hydrolysis. The hydrolysis was carried out at 45 and 60℃ for 90 and 180 min. Chemical structure, crystallinity and thermal stability of the materials were studied using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) analysis and thermogravimetric analysis (TGA), respectively. Morphology and particle size of nanocellulose were also studied using field emission scanning electron microscope (FE-SEM). FTIR results confirmed that lignin and hemicellulose were eliminated after alkali and bleaching treatments. These chemical treatments resulted in an improvement in the crystallinity and thermal stability of SCB. Sphere shape nanocellulose particles were observed by FE-SEM. With increasing hydrolysis time and temperature, the crystallinity of nanocellulose was increased but particle size and thermal stability were decreased.

scholarly journals Antiangiogenic potential of Jatropha curcas latex in the chick chorioallantoic membrane model

2019 ◽  
Vol 29 (1) ◽  
pp. 32157
Author(s):  
Luciane Madureira Almeida ◽  
Elisa Flávia Luiz Cardoso Bailão ◽  
Illana Reis Pereira ◽  
Fabrício Alves Ferreira ◽  
Patrícia Lima D'Abadia ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Jatropha Curcas ◽  
Physicochemical Characterization ◽  
Chorioallantoic Membrane ◽  
Angiogenesis Inhibitor ◽  
Negative Control ◽  
New Drugs ◽  
Membrane Model ◽  
Chick Chorioallantoic Membrane

AIMS: To perform a physicochemical and phytochemical characterization of Jatropha curcas latex and to investigate its antiangiogenic potential. METHODS: We performed an initial physicochemical characterization of J. curcas latex using thermal gravimetric analyses and Fourier Transform Infrared spectroscopy. After that, phenols, tannins and flavonoids were quantified. Finally, the potential of J. curcas latex to inhibit angiogenesis was evaluated using the chick chorioallantoic membrane model. Five groups of 20 fertilized chicken eggs each had the chorioallantoic membrane exposed to the following solutions: (1) water, negative control; (2) dexamethasone, angiogenesis inhibitor; (3) Regederm®, positive control; (4) 25% J. curcas latex diluted in water; (5) 50% J. curcas latex diluted in water; and (6) J. curcas crude latex. Analysis of the newly-formed vascular net was made through captured images and quantification of the number of pixels. Histological analyses were performed to evaluate the inflammation, neovascularization, and hyperemia parameters. The results were statically analyzed with a significance level set at p ˂0.05.RESULTS: Physicochemical characterization showed that J. curcas latex presented a low amount of cis-1.4-polyisoprene, which reduced its elasticity and thermal stability. Phytochemical analyses of J. curcas latex identified a substantial amount of phenols, tannins, and flavonoids (51.9%, 11.8%, and 0.07% respectively). Using a chick chorioallantoic membrane assay, we demonstrated the antiangiogenic potential of J. curcas latex. The latex induced a decrease in the vascularization of the membranes when compared with neutral and positive controls (water and Regederm®). However, when compared with the negative control (dexamethasone), higher J. curcas latex concentrations showed no significant differences.CONCLUSIONS: J. curcas latex showed low thermal stability, and consisted of phenols, tannins, and flavonoids, but little or no rubber. Moreover, this latex demonstrated a significant antiangiogenic activity on a chick chorioallantoic membrane model. The combination of antimutagenic, cytotoxic, antioxidant and antiangiogenic properties makes J. curcas latex a potential target for the development of new drugs.

scholarly journals Preparation and characterization of polyhedral oligomeric silsesquioxane/polystyrene nanocomposites

e-Polymers ◽  
2012 ◽  
Vol 12 (1) ◽  
Author(s):  
Benhong Yang ◽  
Meng Li ◽  
Yun Wu ◽  
Kang Wang
Keyword(s):  
Thermal Stability ◽  
Thermal Property ◽  
Polyhedral Oligomeric Silsesquioxane ◽  
29Si Nmr ◽  
Solution Blending ◽  
Oligomeric Silsesquioxane ◽  
Tga And Dsc ◽  
Thermal Stability Of

AbstractSeveral inorganic/organic nanocomposites were prepared via solution-blending of cage-like octahexyl-polyhedral oligomeric silsesquioxane (Oh-POSS) with polystyrene (PS) in THF solvent. FTIR and 29Si-NMR were employed to characterize the structures of the nanocomposites. SEM pictures showed that the sample films were smooth and no POSS aggregation was observed when POSS content was lower than 1.0 wt%. TGA and DSC were used to investigate the thermal property. The results showed that the incorporation of nanosized Oh-POSS enhanced the thermal stability of PS with low POSS content. When 1.0 wt% of Oh-POSS was incorporated into PS matrix, the Tg and Td increased by 7.7 °C and 8.2 °C, respectively. However, higher POSS contents (>1.0 wt%) would deteriorate the thermal property of the nanocomposites due to the severe congregation of POSS..

Systematic Characterization of Different Quaternary Ammonium Salts to be Used in Organoclays

2012 ◽  
Vol 727-728 ◽  
pp. 1552-1556
Author(s):  
Renata Barbosa ◽  
Dayanne Diniz Souza ◽  
Edcleide Maria Araújo ◽  
Tomás Jefférson Alves de Mélo
Keyword(s):  
Thermal Stability ◽  
Quaternary Ammonium ◽  
Chemical Structure ◽  
Quaternary Ammonium Salts ◽  
Ammonium Salts ◽  
Degradation Mechanisms ◽  
Scanning Calorimetry ◽  
Higher Temperature ◽  
Thermal Stability Of

Studies of degradation have verified that the decomposition of some quaternary ammonium salts can begin to be significant at the temperature of about 180 ° C and like most thermoplastics are processed at least around this temperature, the thermal stability of the salt in clay should always be considered. Some salts are more stable than others, being necessary to study the degradation mechanisms of each case. In this work, four quaternary ammonium salts were characterized by differential scanning calorimetry (DSC) and thermogravimetry (TG). The results of DSC and TG showed that the salts based chloride (Cl-) anion begin to degrade at similar temperatures, while the salt based bromide (Br-) anion degrades at higher temperature. Subsequently, a quaternary ammonium salt was chosen to be used in organoclays, depending on its chemical structure and its thermal behavior.

Characterization of Thermal Stability of the Escherichia coli Fapy–DNA Glycosylase

2001 ◽  
Vol 288 (1) ◽  
pp. 121-128 ◽  
Author(s):  
Serguei V. Kuznetsov ◽  
Olga M. Sidorkina ◽  
Jacques Laval ◽  
Anjum Ansari
Keyword(s):  
Escherichia Coli ◽  
Thermal Stability ◽  
Dna Glycosylase ◽  
Thermal Stability Of

Synthesis and Characterization of Some Functional Luminol Derivatives with Aromatic Substituted Groups

2011 ◽  
Vol 197-198 ◽  
pp. 606-609 ◽  
Author(s):  
Ti Feng Jiao ◽  
Yuan Yuan Xing ◽  
Jing Xin Zhou ◽  
Wei Wang
Keyword(s):  
Molecular Structure ◽  
Thermal Stability ◽  
Molecular Structures ◽  
Synthesis And Characterization ◽  
Functional Material ◽  
Aromatic Substituent ◽  
The Difference ◽  
Imide Group ◽  
Thermal Stability Of

Some functional luminol derivatives with aromatic substituted groups have been designed and synthesized from the reaction of the corresponding aromatic acyl chloride precursors with luminol. It has been found that depending on the size of aromatic groups, the formed luminol derivatives showed different properties, indicating distinct regulation of molecular skeletons. UV and IR data confirmed commonly the formation of imide group as well as aromatic segment in molecular structures. Thermal analysis showed that the thermal stability of luminol derivatives with p-phthaloyl segment was the highest in those derivatives. The difference of thermal stability is mainly attributed to the formation of imide group and aromatic substituent groups in molecular structure. The present results have demonstrated that the special properties of luminol derivatives can be turned by modifying molecular structures of objective compounds with proper substituted groups, which show potential application in functional material field and ECL sensor.

KARBON LİF ÜRETİMİNDE POLİAKRİLONİTRİL ELYAFLARIN TERMAL OKSİDASYONU

2021 ◽  
Vol 8 (17) ◽  
pp. 160-170
Author(s):  
Mahbubor Rahman ◽  
Tuba DEMIREL ◽  
Ismail KARACAN
Keyword(s):  
Thermal Stability ◽  
Aqueous Solution ◽  
Thermal Oxidation ◽  
Oxidation Process ◽  
Ammonium Persulfate ◽  
Oxidation Reactions ◽  
Carbon Yield ◽  
Thermal Stability Of ◽  
Pan Fibers

Thermal oxidation of polyacrylonitrile (PAN) fibers was accomplished at temperatures up to 250°C for different oxidation times. Chemical integration of PAN fibers with an aqueous solution of ammonium persulfate was performed before starting thermal oxidation. The results recommend that ammonium persulfate integration enhanced the oxidation reactions of the PAN fibers and resulting in enhanced thermal stability. Ammonium persulfate impregnation followed by the oxidation process in the air environment leads to significant deviations in the characteristics of PAN fibers. To perform structural characterization of the raw and ammonium persulfate (APS) incorporated and stabilized samples, XRD, IR-spectroscopy, TGA was executed in this study. Investigation of the XRD and infrared spectroscopy outcomes recommended quick aromatization reactions with growing oxidation periods. The TGA traces indicated a comparative enhancement in the thermal stability of the PAN fibers by the increased carbon yield with the rise of the oxidation time. The overall findings recommend that ammonium persulfate incorporation was very influential in stimulating the oxidation process.

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