scholarly journals Grafting versus Crosslinking of Silk Fibroin-g-PNIPAM via Tyrosine-NIPAM Bridges

Molecules ◽  
2019 ◽  
Vol 24 (22) ◽  
pp. 4096 ◽  
Author(s):  
Ionut-Cristian Radu ◽  
Iuliana-Elena Biru ◽  
Celina-Maria Damian ◽  
Andreea-Cristina Ion ◽  
Horia Iovu ◽  
...  
Keyword(s):  
Silk Fibroin ◽  
Photoelectron Spectroscopy ◽  
Polymer Network ◽  
Chemical Characterization ◽  
Redox System ◽  
Spatial Arrangement ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Polymeric Networks ◽  
Bombyx Mori Silk

This paper reports the synthesis and complex characterization of novel polymeric networks based on the crosslinking of Bombyx mori silk fibroin via poly(N-isopropylacrylamide) bridges generated by an ammonium cerium nitrate redox system. The research study gives an understanding of the polymerization mechanism in terms of the generation of radical sites, radical growth and termination reaction, as well as the involvement of modifications on silk fibroin structure and properties. The physico-chemical characterization was carried out by FTIR-ATR, X-ray photoelectron spectroscopy and RAMAN spectroscopy with unravelling the chemical modification. The structural characterization and spatial arrangement by secondary structure were carried out by X-ray diffraction and circular dichroism. The thermal behavior and thermal stability were evaluated by differential scanning calorimetry and thermogravimetric analysis. The novel complex polymer network is intended to be used in the field of smart drug delivery systems.

scholarly journals Spectroscopic and physical–chemical characterization of ambazone–glutamate salt

2011 ◽  
Vol 26 (2) ◽  
pp. 115-128 ◽  
Author(s):  
Marieta Muresan-Pop ◽  
Irina Kacsó ◽  
Xenia Filip ◽  
Emilia Vanea ◽  
G. Borodi ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Chemical Characterization ◽  
Analytical Techniques ◽  
Spectroscopic Techniques ◽  
Scanning Calorimetry ◽  
Monoclinic System ◽  
X Ray ◽  
Fourier Transformed Infrared Spectroscopy ◽  
Combined Use ◽  
Solid Form

Ambazone monohydrate C8H11N7S · H2O (AMB), a well-known antimicrobial compound, was used together with Glutamic Acid C5H9NO4(Glu) to obtain a new solid form using the solvent-drop grinding procedure. The screening of the new solid form was best achieved by the combined use of X-ray Powder Diffraction (XRPD) and several spectroscopic techniques (Fourier Transformed Infrared Spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS), Raman and13C-NMR spectroscopy) together with Differential Scanning Calorimetry (DSC), Differential thermal analysis and thermogravimetry (DTA–TGA). The combination of the mentioned analytical techniques allows the compound to be assigned to an ambazone–glutamate salt which crystallizes in monoclinic system having the following lattice parameters:a=9.8352,b=4.7014,c=40.0987 Å and β=94.505°. DSC, TGA data and the before mentioned spectroscopic techniques support the ambazone–glutamate salt formation.

scholarly journals Chemical modification of Bombyx mori silk fibers with vinyl groups for thiol-ene click chemistry

BMC Chemistry ◽  
2019 ◽  
Vol 13 (1) ◽  
Author(s):  
Xiaoning Zhang ◽  
Jianwei Liang ◽  
Zhenyu Chen ◽  
Carrie Donley ◽  
Yuling Liu ◽  
...  
Keyword(s):  
Chemical Modification ◽  
Click Chemistry ◽  
Bombyx Mori ◽  
Photoelectron Spectroscopy ◽  
Scanning Calorimetry ◽  
Silk Fibers ◽  
X Ray ◽  
Diphenyltetrazolium Bromide ◽  
Bombyx Mori Silk ◽  
Scanning Electron

Abstract Natural Bombyx mori silk fibroin (SF) fibers were modified with 2-methacryloyloxyethyl isocyanate (MOI) first for the introduction of vinyl groups. Then, 1H,1H,2H,2H-perfluorodecanethiol was grafted onto the SF fibers via thiol-ene click chemistry using ultraviolet light. The formations of MOI-modified and PFDT-grafted SF fibers were analyzed using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, respectively. The morphology of samples was also revealed by a scanning electron microscope. In addition, differential scanning calorimetry results demonstrated that SF fibers did not show significant change in thermal behavior, regardless of the chemical modification. To confirm the cytotoxicity of the prepared SF fibers, MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay was performed, and no toxicity was observed with PFDT-grafted SF fibers. The results also showed that PFDT-grafted SF fibers exhibited good antifouling properties when Chlorella vulgaris (C. vulgaris) was selected as a model for algal cells adhesion experiment.

scholarly journals pH-controlled synthesis of sustainable lauric acid/SiO2 phase change material for scalable thermal energy storage

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shafiq Ishak ◽  
Soumen Mandal ◽  
Han-Seung Lee ◽  
Jitendra Kumar Singh
Keyword(s):  
Electron Microscopy ◽  
Phase Change ◽  
Lauric Acid ◽  
Photoelectron Spectroscopy ◽  
Phase Change Materials ◽  
Precursor Solution ◽  
Thermal Reliability ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Heating And Cooling

AbstractLauric acid (LA) has been recommended as economic, eco-friendly, and commercially viable materials to be used as phase change materials (PCMs). Nevertheless, there is lack of optimized parameters to produce microencapsulated PCMs with good performance. In this study, different amounts of LA have been chosen as core materials while tetraethyl orthosilicate (TEOS) as the precursor solution to form silicon dioxide (SiO2) shell. The pH of precursor solution was kept at 2.5 for all composition of microencapsulated LA. The synthesized microencapsulated LA/SiO2 has been characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), X-Ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM), and Transmission electron microscopy (TEM). The SEM and TEM confirm the microencapsulation of LA with SiO2. Thermogravimetric analysis (TGA) revealed better thermal stability of microencapsulated LA/SiO2 compared to pure LA. PCM with 50% LA i.e. LAPC-6 exhibited the highest encapsulation efficiency (96.50%) and encapsulation ratio (96.15%) through Differential scanning calorimetry (DSC) as well as good thermal reliability even after 30th cycle of heating and cooling process.

Preparation and Characterization of Ni2+-Montmorillonite/Polyvinyl Alcohol Water-Soluble Nanocomposite Film

2005 ◽  
Vol 13 (8) ◽  
pp. 839-846 ◽  
Author(s):  
Li-Ping Wang ◽  
Yun-Pu Wang ◽  
Fa-Ai Zhang
Keyword(s):  
Polyvinyl Alcohol ◽  
Photoelectron Spectroscopy ◽  
Thermal Characteristics ◽  
Water Soluble ◽  
Scanning Calorimetry ◽  
Xps Spectra ◽  
X Ray ◽  
Alcohol Water ◽  
Ft Ir ◽  
Silicate Layers

A new type of nano-composite film was prepared from polyvinyl alcohol, Ni2+-montmorillonite (Ni2+-MMT), defoamer, a levelling agent and a plasticizer. Its thermal characteristics were studied by Differential Scanning Calorimetry (DSC). The intermolecular interactions were measured by Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS), and the tensile strength (TS) and elongation at break (%E) were measured. The microstructures were studied by X-ray diffraction (XRD) and atomic force microscopy (AFM). FT-IR and XPS spectra indicated that cross-linking has taken place between PVA and Ni2+-MMT. XRD and AFM indicate that the PVA molecules had inserted themselves into the silicate layers of MMT, exfoliating them and dispersing them randomly into the PVA matrix. Compared to pure PVA film, the TS of the films was increased and %E decreased when the Ni2+-Montmorillonite was added and the dissolution temperature of the film was also reduced.

scholarly journals Photocatalytic activity of graphene oxide–TiO 2 thin films sensitized by natural dyes extracted from Bactris guineensis

2019 ◽  
Vol 6 (3) ◽  
pp. 181824 ◽  
Author(s):  
William Vallejo ◽  
Angie Rueda ◽  
Carlos Díaz-Uribe ◽  
Carlos Grande ◽  
Patricia Quintana
Keyword(s):  
Thin Films ◽  
Raman Spectroscopy ◽  
Graphene Oxide ◽  
Photocatalytic Degradation ◽  
Photoelectron Spectroscopy ◽  
Chemical Characterization ◽  
Sem Analysis ◽  
Visible Range ◽  
X Ray ◽  
Natural Sensitizer

This study synthesized and characterized composites of graphene oxide and TiO 2 (GO–TiO 2 ). GO–TiO 2 thin films were deposited using the doctor blade technique. Subsequently, the thin films were sensitized with a natural dye extracted from a Colombian source ( Bactris guineensis ). Thermogravimetric analysis, X-ray diffraction, Raman spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and diffuse reflectance measurements were used for physico-chemical characterization. All the samples were polycrystalline in nature, and the diffraction signals corresponded to the TiO 2 anatase crystalline phase. Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR) verified the synthesis of composite thin films, and the SEM analysis confirmed the TiO 2 films morphological modification after the process of GO incorporation and sensitization. XPS results suggested a possibility of appearance of titanium (III) through the formation of oxygen vacancies (O v ). Furthermore, the optical results indicated that the presence of the natural sensitizer and GO improved the optical properties of TiO 2 in the visible range. Finally, the photocatalytic degradation of methylene blue was studied under visible irradiation in aqueous solution, and pseudo-first-order model was used to obtain kinetic information about photocatalytic degradation. These results indicated that the presence of GO has an important synergistic effect in conjunction with the natural sensitizer, reaching a photocatalytic yield of 33%.

scholarly journals Copper microsphere hybrid mesoporous carbon as matrix for preparation of shape-stabilized phase change materials with improved thermal properties

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Yi Liu ◽  
Yan Chen ◽  
Junwei Zhang ◽  
Junkai Gao ◽  
Zhi Han
Keyword(s):  
Thermal Properties ◽  
Phase Change ◽  
Photoelectron Spectroscopy ◽  
Mesoporous Carbon ◽  
Phase Change Materials ◽  
Copper Ions ◽  
Thermal Constant ◽  
Step Method ◽  
Scanning Calorimetry ◽  
X Ray

Abstract Copper microsphere hybrid mesoporous carbon (MPC-Cu) was synthesized by the pyrolysis of polydopamine microspheres doped with copper ions that were prepared using a novel, facile and simple one-step method of dopamine biomimetic polymerization and copper ion adsorption. The resulting MPC-Cu was then used as a supporter for polyethylene glycol (PEG) to synthesize shape-stabilized phase change materials (PEG/MPC-Cu) with enhanced thermal properties. PEG/MPC-Cu was studied by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, differential scanning calorimetry and thermal constant analysis. The results demonstrated that the thermal conductivity of PEG/MPC-Cu was 0.502 W/(m K), which increased by 100% compared to pure PEG [0.251 W/(m K)]. The melting enthalpy of PEG/MPC-Cu was 95.98 J/g, indicating that PEG/MPC-Cu is a promising candidate for future thermal energy storage applications. In addition, the characterization results suggested that PEG-MPC-Cu possessed high thermal stability. Therefore, the method developed in this paper for preparing shape-stabilized phase change materials with improved thermal properties has substantial engineering application prospects.

scholarly journals Effect of the Degree of Substitution on the Hydrophobicity, Crystallinity, and Thermal Properties of Lauroylated Amaranth Starch

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2548
Author(s):  
Vicente Espinosa-Solis ◽  
Yunia Verónica García-Tejeda ◽  
Everth Jimena Leal-Castañeda ◽  
Víctor Barrera-Figueroa
Keyword(s):  
Photoelectron Spectroscopy ◽  
Thermal Characterization ◽  
Fatty Acyl ◽  
Degree Of Substitution ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Amaranthus Hypochondriacus ◽  
Two Samples ◽  
Acyl Chains

In this paper, we consider amaranth starch extracted from the seeds of Amaranthus hypochondriacus L. An amphiphilic character is conferred to the starch by a chemical modification, which involves an esterification by lauroyl chloride at three modification levels. The degree of substitution (DS) after the modification ranged from 0.06 to 1.16. X-ray photoelectron spectroscopy analysis confirmed the presence of fatty acyl chains on the surface of the esterified starches. The hydrophobicity of starches was confirmed by their adsorption isotherms, which showed a decrease in the moisture adsorption of lauroylated as DS increased. X-ray diffraction analysis revealed a higher crystallinity, which was observed in the two samples subjected to the highest levels of modification. A higher crystallinity is related to a higher gelatinization enthalpy. These results are in agreement with the thermal characterization obtained by differential scanning calorimetry (DSC). An inhibition of the retrogradation properties of lauroylated amaranth starches was also observed.

scholarly journals Influence of Different Birnessite Interlayer Alkali Cations on Catalytic Oxidation of Soot and Light Hydrocarbons

Catalysts ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 507
Author(s):  
Tomasz Jakubek ◽  
Camillo Hudy ◽  
Paweł Stelmachowski ◽  
Ewa Nowicka ◽  
Stan Golunski ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Manganese Oxides ◽  
Combustion Engine ◽  
Propane Conversion ◽  
Light Hydrocarbons ◽  
Soot Combustion ◽  
Scanning Calorimetry ◽  
Alkali Cations ◽  
X Ray ◽  
Tight Contact

A series of layered birnessite (AMn4O8) catalysts containing different alkali cations (A = H+, Li+, Na+, K+, Rb+, or Cs+) was synthesized. The materials were thoroughly characterized using X-ray diffraction, X-ray fluorescence, X-ray photoelectron spectroscopy, Raman spectroscopy, specific surface area analysis, work function, thermogravimetry/differential scanning calorimetry, and transmission electron microscopy. The catalytic activity in soot combustion in different reaction modes was investigated (tight contact, loose contact, loose contact with NO addition). The activity in the oxidation of light hydrocarbons was evaluated by tests with methane and propane. The obtained results revealed that alkali-promoted manganese oxides are highly catalytically active in oxidative reactions. In soot combustion, the reaction temperature window was shifted by 195 °C, 205 °C, and 90 °C in tight, loose + NO, and loose contact conditions against uncatalyzed oxidation, respectively. The catalysts were similarly active in hydrocarbon combustion, achieving a 40% methane conversion at 600 °C and a total propane conversion at ~450 °C. It was illustrated that the difference in activity between tight and loose contacts can be successfully bridged in the presence of NO due to its facile transformation into NO2 over birnessite. The particular activity of birnessite with H+ cations paves the road for the further development of the active phase, aiming at alternative catalytic systems for efficient soot, light hydrocarbons, and volatile organic compounds removal in the conditions present in combustion engine exhaust gases.

Anelastic Phenomena at the Fibre-Matrix Interface of the Ti6Al4V-SiCf Composite

2010 ◽  
Vol 425 ◽  
pp. 263-270 ◽  
Author(s):  
Paolo Deodati ◽  
Riccardo Donnini ◽  
Saulius Kaciulis ◽  
Alessio Mezzi ◽  
Roberto Montanari ◽  
...  
Keyword(s):  
Activation Energy ◽  
Relaxation Time ◽  
Photoelectron Spectroscopy ◽  
Chemical Characterization ◽  
Matrix Interface ◽  
Ion Sputtering ◽  
Mechanical Spectroscopy ◽  
Monolithic Alloy ◽  
X Ray ◽  
Fibre Matrix

The composite, consisting of Ti6Al4V matrix reinforced by unidirectional SiC fibres (SCS-6), has been investigated by mechanical spectroscopy at temperatures up to 1,173 K. For comparison, the same experiments have been performed on the corresponding monolithic alloy. The internal friction (IF) spectrum of the composite exhibits a new relaxation peak superimposed to an exponentially increasing background. This peak, which is not present in the monolithic alloy, has an activation energy H = 186 kJ mol-1 and a relaxation time 0 = 2.3 x 10-15 s. The phenomenon has been attributed to a reorientation of interstitial-substitutional pairs in the  phase of Ti6Al4V matrix around the fibres. This explanation is supported by the results of micro-chemical characterization carried out by X-ray photoelectron spectroscopy (XPS) combined with Ar ion sputtering.

Sign in / Sign up

Export Citation Format

Share Document