Methylxanthines binding with yeast total RNA in the presence of Mg2+: a speed vac-centrifugation-facilitated solid-state Fourier transform infrared analysis

2005 ◽  
Vol 339 (1) ◽  
pp. 179-181 ◽  
Author(s):  
I. Maria Johnson ◽  
R. Malathi
Keyword(s):  
Fourier Transform ◽  
Solid State ◽  
Fourier Transform Infrared ◽  
Infrared Analysis ◽  
Total Rna

Vulcanization Studies of Elastomers Using Solid-State Carbon-13 NMR

1983 ◽  
Vol 56 (5) ◽  
pp. 971-994 ◽  
Author(s):  
Dwight J. Patterson ◽  
Jack L. Koenig ◽  
J. Reid Shelton
Keyword(s):  
Fourier Transform ◽  
Free Radical ◽  
Solid State ◽  
Natural Rubber ◽  
Fourier Transform Infrared ◽  
Difference Spectrum ◽  
Dipolar Interaction ◽  
Infrared Analysis ◽  
Dicumyl Peroxide ◽  
The Difference

Abstract With the use of solid state carbon-13 NMR, changes in the structure of natural rubber and cis-polybutadiene were observed spectroscopically. Cis-trans conversion has been shown to occur in the naturaal rubber by the rearrangement of the allylic free radical. At least four structurally different methyl groups have been detected in the crosslinking of natural rubber by dicumyl peroxide, which indicates that the simple combination of allyic free radical is an oversimplification of the curing process. Quaternary aliphatic carbons have been detected which results from double bond migration. Polybutadiene showed only methine and methylene carbons present in the crosslinked network with a small amount of methyl end-groups. The increase in the line width of the highly crosslinked elastomers was shown to be dominated by the carbon-hydrogen static dipolar interaction. Fourier-transform infrared analysis observed the formation of a molecular complex between dicumyl peroxide and polybutadiene. The formation of trans double bonds was observed in the infrared spectra of polybutadiene. Weak broad bands around 1320 cm−1 were observed in the difference spectrum of cured rubbers and were assigned to carbon-carbon crosslinks. From the structural interpretation of spectra obtained from solid state carbon-13 NMR and Fourier-transform infrared, models are proposed for the crosslinked networks of natural rubber and polybutadiene, obtained from peroxide vulcaniation.

scholarly journals Adsorption of hexavalent chromium by activated carbon obtained from a waste lignocellulosic material (Ziziphus jujuba cores): Kinetic, equilibrium, and thermodynamic study

2018 ◽  
Vol 36 (3-4) ◽  
pp. 1066-1099 ◽  
Author(s):  
Radia Labied ◽  
Oumessaad Benturki ◽  
Adh’ Ya Eddine Hamitouche ◽  
André Donnot
Keyword(s):  
Fourier Transform ◽  
Activated Carbon ◽  
Hexavalent Chromium ◽  
Chemical Activation ◽  
Fourier Transform Infrared ◽  
Infrared Analysis ◽  
Order Kinetic ◽  
Lignocellulosic Material ◽  
Ziziphus Jujuba ◽  
Key Functional Groups

In aqueous solutions, hexavalent chromium Cr(VI) was successfully removed by activated carbon “ Z. jujuba rubidium carbonate-activated carbon” obtained from waste lignocellulosic material ( Ziziphus jujuba cores). Rubidium carbonate was used to prepare Z. jujuba rubidium carbonate-activated carbon by chemical activation using a 1:1 w/w ratio. Our results indicate that the obtained surface area of the activated carbon was equal to 608.31 m2/g. The adsorption study of Cr(VI) was investigated under batch conditions at constant stirring speed (220 r/min). Factors such as pH (1–6), temperature (20–40°C), adsorbent concentration (0.5–3 g/l), and initial Cr(VI) concentration (50–500 mg/l) were all studied to attain the maximum removal efficiency. Prior to the adsorption process, the morphology, elementary composition, and loss mass of activated carbon were characterized using scanning electron microscopy, X-ray fluorescence spectrometry, Fourier transform infrared spectroscopy, and thermogravimetric analysis. Fourier transform infrared analysis of the adsorbent demonstrated the presence of key functional groups associated with the adsorption phenomenon such as those of hydroxyl and aromatic groups. The obtained results showed that the optimal conditions for a maximum adsorption efficiency are 2 for pH, 1 g/l for activated carbon dosage and 100 mg/l for Cr(VI) concentration. The removal percentage increased from 27.2 to 62.08%. The kinetic sorption was described by a pseudo-second-order kinetic equation ( R2 ≈ 0.995). The Tóth ( R2 = 0.997) and Elovich models were best to explain the sorption phenomenon. Thermodynamic studies showed that the adsorption of Cr(VI) onto activated carbon was feasible, spontaneous, and endothermic at 20–40°C. This novel Z. jujuba rubidium carbonate-activated carbon derived from Z. jujuba core has been found to be effective for the removal of Cr(VI) and not harmful to the ecosystem.

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