The influence of temperature on the corrosion behaviour of high nitrogen austenitic stainless steel in chloride media
B. R. Tzaneva
Department of Chemistry, TechnicalUniversity, 8 Kliment Ohridsky Blvd, 1000 Sofia, Bulgaria
E-mail:
Abstract:
The electrochemical behaviour of high nitrogen SS in comparison of conventional grade 304 SS was examined in aqueous 3.5% chloride solution at 20-80 oC using open circuit potential vs. time, potentiodinamic and galvanostatic tests. The raising of the temperature was found to have no important influence on the corrosion potential, but destabilise the passive film formation on both steels. At the critical value of anodic polarisation the passive films were damaged and pitting corrosion occurs at lower potential with the increasing of temperature. The high nitrogen steel demonstrates faster formation of passive films, but pitting potential of this steel is more sensitive to temperature changes in comparison with those of chromium-nickel one. The temperature has slight influence on repassivation process, which is generally steel composition dependent. At all experimental conditions the nitrogen steel has greater difficulty to repassivate.
Preparation and characterization of composite hydrocolloid films from sodium alginate and high methoxyl pectin
Sv. M. Dyankova*, A.O. Solak
Institute of Cryobiology and Food Technologies, BG – 1407 Sofia, Bulgaria
e-mail:
tel. +359 2 862 61 04
Abstract
A technology for obtaining of a composite biodegradable film on the basis of sodium alginate and apple high methoxyl (HM) pectin has been developed. Good mechanical characteristics have been established when using the two polysaccharides in proportion 1:1. For them theultimate tensile strenght (TS)was 53,53MPa, the elongation at ultimate strenght(Е)was 34,48%,Young’smodulus (YM)- 202,84 MPa. The composite film showed very poor solubility at low pH, including in a simulated gastric juice. At pH values above 4,0 the alginate films showed slower and the composite films faster and complete disintegration in the medium.Due to the good mechanical characteristics and selective solubility depending on pH, the composite sodium alginate-HM pectin films are appropriate as material for encapsulating of biologically active substances or microorganisms with low activity or survival, under conditions of low pH.
Poly-(4-vinylpyridinium nitrate) and silica sulfuric acid (SiO2-OSO3H): an efficient and metal-free oxidizing media for the oxidation of 1,4-dihydropyridine and urazole derivatives
Arash Ghorbani-Choghamarani, Maryam Hajjami, Masoomeh Norouzi, Arezoo Amiri
Department of Chemistry, Faculty of Science, Ilam University, P.O. Box 69315516, Ilam, Iran
Corresponding author. Tel.: +98 841 2227022; Fax: +98 841 2227022; E-mail or
Abstract: An efficient and metal-free oxidative aromatization of alkyl or aryl-substituted derivatives of 1,4-dihydropyridines and urazoles has been studied using poly-(4-vinylpyridinium nitrate) in the presence of silica sulfuric acid (SiO2-OSO3H). The reaction was carried out in dichloromethane at room temperature and the products were isolated in good to excellent yields.
Methanesulfonic acid Catalyzed One-Pot Synthesis of Pyrano[2,3-c] pyrazole Derivatives in Water
Majid M. Heravi * a, Najme Javanmardi a, Hossein A.Oskooiea,
Bita Baghernejad b
aDepartment of Chemistry, School of Science, Alzahra University, Tehran, Iran
b Department of Chemistry, School of Sciences, Payame Noor University(PNU), 19395-3697, i.r. of Iran
Correspondence to: Majid M. Heravi, Prof.Department of Chemistry, School of Science, Alzahra University, Tehran, Iran
E-mail: Tel/Fax: +982188047861
Abstract:
A simple and efficient synthesis of 1,4-Dihydropyrano[2,3-c] pyrazoles was achieved via a one-pot three-component reaction of an aromatic aldehyde, malonitrile and 3-methyl-1-phenyl-2-pyrazolin-5-one usingmethanesulfonic acid as a catalyst in good yields.
Preparation, Characterization and Photocatalytic Activity of
TiO2/CoO nanocomposite
Bahar Khodadadi*a, Mohammad Sabeti a, Babak Nahri-Niknafs b,
Shahram Moradi Dehaghi c, Parviz Aberomand Azar d, Sanaz Raeis Farshid e
aDepartment of Chemistry, University of Qom, Qom, Iran
b Department of Chemistry, Faculty of Science, Islamic Azad University, Karaj Branch, Karaj, Iran.
c Department of Chemistry, Tehran North Branch of Islamic Azad University, Tehran, Iran
d Department of Chemistry, Science and Research Branch of Islamic Azad University, Tehran, Iran &
e Department of Chemistry, Islamic Azad University of Lahijan, Lahijan, Iran
Correspondence to: Dr. Bahar Khdadadi, Department of Chemistry, University of Qom, Qom, Iran
Tel: +98 251 2853311; +98 912 6530455; Fax: +98 251 2855684
E-mail: ,
Abstract
TiO2/CoO nanocomposites were prepared by the sol-gel method with and without additives such as carboxy methyl cellulose (CMC), polyvinylpyrrolidone, (PVP), and hydroxypropyl cellulose (HPC). The structures and properties were characterized with Fourier Transform Infra Red Spectroscopy (FT-IR), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray Spectroscopy (EDAX) methods. Furthermore, the photocatalytic activity under UV-irradiation to remove organic pollutant was investigated. The results have revealed that, additives have a significant effect on the particle size distribution and photocatalytic activity of TiO2/CoO nanocomposites. SEM pictures have shown that the particle size of TiO2/CoO powder with additives was smaller than other samples without any additive.
Correspondence: (A. Ghorbani-Choghamarani), Ilam University, Ilam, Iran, E-mail: or