Starch-based fixative with proper substitution degree for controlling dissolved and colloidal substances in a bleached chemithermomechanical pulp

2014 ◽  
Vol 66 (11-12) ◽  
pp. 992-997 ◽  
Author(s):  
Lijun Wang ◽  
Tongzhou Di ◽  
Yiqian Zhang ◽  
Lingzhi Luo ◽  
Huifang Zhao
Keyword(s):  
Substitution Degree ◽  
Dissolved And Colloidal Substances

scholarly journals SINTESIS O-KARBOKSIMETIL KITOSAN PADA BERBAGAI KONSENTRASI NaOH DAN SUHU REAKSI SERTA APLIKASINYA SEBAGAI ANTIBAKTERI

KOVALEN ◽  
2017 ◽  
Vol 3 (1) ◽  
pp. 33 ◽  
Author(s):  
Jaya Hardi ◽  
Nurakhirawati Nurakhirawati ◽  
Ahmad Ridhay ◽  
Musdalifah Musdalifah
Keyword(s):  
Antibacterial Activity ◽  
Reaction Temperature ◽  
Primary Amine ◽  
Carboxymethyl Chitosan ◽  
Ftir Spectrum ◽  
Bending Vibration ◽  
Randomized Design ◽  
Substitution Degree ◽  
Completely Randomized Design

The research about the influence of NaOH concentrations and reaction temperature to O-Carboxymethyl Chitosan (O-CMC) synthesis and it is antibacterial application was done. This research intent on detect NaOH concentration and reaction temperature that resulting of O-CMC with highest of yield, solubility, and substitution degrees, and also to find out FTIR spectrum and antibacterial activity of O-CMC. The produce of O-CMC was done by using a Completely Randomized Design (CRD) with the variation of NaOH concentration of 20%, 30%, 40%, 50%, and 60%, and also reaction temperature of 20, 30, and 40oC. The result was showed that on the NaOH concentration of 60% (w/v) and temperature of 30oC was resulted highest of yield, solubility, and substitution degrees of 41.5%, 31 g/L, and 0.67, respectively. FTIR spectrum was showed that bending vibration of primary amine (-NH2) give two bands for O-CMC. The broadest inhibition area of O-CMC (1.43 cm) was showed on Salmonella sp.Keywords: chitosan, O-CMC, substitution degree, antibacterial

Biophysical properties of electrospun chitosan-grafted poly(lactic acid) nanofibrous scaffolds loaded with chondroitin sulfate and silver nanoparticles

2021 ◽  
pp. 088532822110464
Author(s):  
Alexandre F Júnior ◽  
Charlene A Ribeiro ◽  
Maria E Leyva ◽  
Paulo S Marques ◽  
Carlos R J Soares ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Lactic Acid ◽  
Proton Nuclear Magnetic Resonance ◽  
Poly Lactic Acid ◽  
Fibroblast Cells ◽  
Biophysical Properties ◽  
Electrospinning Technique ◽  
Average Pore ◽  
H Nmr ◽  
Substitution Degree

The aim of this work was to study the biophysical properties of the chitosan-grafted poly(lactic acid) (CH-g-PLA) nanofibers loaded with silver nanoparticles (AgNPs) and chondroitin-4-sulfate (C4S). The electrospun CH-g-PLA:AgNP:C4S nanofibers were manufactured using the electrospinning technique. The microstructure of the CH-g-PLA:AgNP:C4S nanofibers was investigated by proton nuclear magnetic resonance (1H-NMR), scanning electron microscopy (SEM), UV-Visible spectroscopy (UV-Vis), X-ray diffraction (XRD), and Fourier transform infrared (ATR-FTIR) spectroscopy. ATR-FTIR and 1H-NMR confirm the CH grafting successfully by PLA with a substitution degree of 33.4%. The SEM measurement results indicated apparently smooth nanofibers having a diameter range of 340 ± 18 nm with porosity of 89 ± 3.08% and an average pore area of 0.27 μm2. UV-Vis and XRD suggest that silver nanoparticles with the size distribution of 30 nm were successfully incorporated into the electrospun nanofibers. The water contact angle of 12.8 ± 2.7° reveals the hydrophilic nature of the CH-g-PLA:AgNP:C4S nanofibers has been improved by C4S. The electrospun CH-g-PLA:AgNP:C4S nanofibers are found to release ions Ag+ at a concentration level capable of rendering an antimicrobial efficacy. Gram-positive bacteria ( S.aureus) were more sensitive to CH-g-PLA:AgNP:C4S than Gram-negative bacteria ( E. coli). The electrospun CH-g-PLA:AgNP:C4S nanofibers exhibited no cytotoxicity to the L-929 fibroblast cells, suggesting cytocompatibility. Fluorescence microscopy demonstrated that C4S promotes the adhesion and proliferation of fibroblast cells onto electrospun CH-g-PLA:AgNP:C4S nanofibers.

Сrystalline structure and dielectric properties of ceramic materials based on AgNbO3

2020 ◽  
Vol 63 (7) ◽  
pp. 75-78
Author(s):  
Polina A. Bezborodova ◽  
◽  
Elena M. Filonenko ◽  
Kseniya R. Erager ◽  
Anatoly V. Butakov ◽  
...  
Keyword(s):  
Rietveld Method ◽  
Average Particle Size ◽  
Ceramic Materials ◽  
Analysis Data ◽  
Molar Ratio ◽  
Average Particle ◽  
Dielectric Parameters ◽  
Low Frequencies ◽  
X Ray ◽  
Substitution Degree

Using the data of qualitative X-ray phase analysis, it was shown that in a wide concentration range at 1223 K compounds based on silver niobate are formed in the condition of the heterovalent substitution of tungsten(VI) ions for niobium(V) ions. These compounds are isomorphic to a perovskite-type structure. Microprobe analysis data allows to determine the homogeneity of the analyzed samples and the correspondence of their experimental compositions to the theoretical ones for the formula Ag1-xNb1-xWxO3. Using the data of X-ray diffraction analysis (Rietveld method) in the Crystallography Data Analysis Software – GSAS, the crystal structure of the obtained compounds was refined. The surface morphology of samples having been obtained at 1373 K was investigated by scanning electron microscopy (SEM). It was shown that with an increase of Nb5+ to W6+ substitution degree for Ag1-xNb1-xWxO3 ceramic samples in the range of the (0.2≤x≤0.8) molar ratio, the average particle size for the studied compositions grows from 1.3 to 5.2 μm, respectively. For the obtained ceramic compounds based on silver niobate with a perovskite-like structure (tetragonal distortion), the temperature-frequency dependences of dielectric parameters in the range 300-900 K were studied. It was found that samples slowly cooled from 1373 K are characterized by low values of (ε ~ 10) and loss (tgδ ~ 0.004 at f = 1 kHz) at room temperature. The ceramics obtained are characterized by relatively high values of dielectric permittivity ε at low frequencies and/or high temperatures. The dielectric parameters of the obtained ceramics are similar to the characteristics of so-called "colossal" dielectric constant materials. The revealed features of the dielectric characteristics of quenched ceramics apparently result from Maxwell-Wagner relaxation at intercrystalline contacts.

scholarly journals The effect of reaction media polarity on the substitution degree value of carboxymethyl kappa-carrageenan (CMKC)

2020 ◽  
Author(s):  
Brilian Zuhroti ◽  
Irma Kartika Kusumaningrum ◽  
Anugrah Ricky Wijaya ◽  
Nuridhia Nisa Purnama
Keyword(s):  
Substitution Degree ◽  
Kappa Carrageenan ◽  
Reaction Media

scholarly journals First study on telomerization of chitosan and guar hemicellulose with butadiene: Influence of reaction parameters on the substitution degree of the biopolymers

2020 ◽  
Vol 483 ◽  
pp. 110706
Author(s):  
Wissam Zahreddine ◽  
Iyad Karamé ◽  
Catherine Pinel ◽  
Laurent Djakovitch ◽  
Franck Rataboul
Keyword(s):  
Reaction Parameters ◽  
Substitution Degree
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