نشریه کاربرد شیمی در محیط زیست
پیاپی 2 (بهار 1389)

The influence of different intensities of ultrasound on the molecular weight of chitosan was investigated. Average molecular weight of ultrasonicated chitosan was determined by measurements of intrinsic viscosity of samples. Intrinsic viscosity of samples decreased exponentially with increasing sonication time. The Schmidt polymer degradation model was used to analyze the molecular weight decay as a function of sonication time as well as rate constant determination. In addition, the structure of the degraded chitosan was characterized by FT-IR spectral analysis. There was no significant change of the total degree of deacetylation (DD) of degraded chitosan compared with the initial chitosan.

sed on positive. Among this positive samples after isolation of antibacterial material with ethyl acetate and inoculation against Staphylococcus) streptomyces samples that able to produce antibiotic and then for distinguishing different biochemical test were subjected with jacard cluster analysis.on the base of this determined characteristics of streptomyces strain in first group is s.americanus,s.atratus,s.anthocyanicuswere identified of antibiotic producers. concluded they are close to the genera streptoverticlum, nokardia with different species.

In this article the equilibrium properties of pure and doped carbon nanotubes in various condition by molecular simulation method was investigated. The carbon nanotubes has exclusive thermodynamic properties that whit adding other atoms for example boron, thispropertiesare changed. Molecular simulation method isuseful tools to investigate the thermodynamic properties at nanoscale. Equilibrium property of doped carbon nanotubes in water solvent is exclusive properties of this system. Water is someone important and applicable solvent that many investigations for this exclusive property are done.abilty for creating hydrogen bonding give exclusive properties. By using of molecular simulation software in Monte Carlo method and radial distribution function for carbon and boron atoms in nanotubes and oxygen and hydrogen atoms in water, hydrophobicity and hydrophilicity of these nanotubes investigated.Monte Carlo simulation done by Mcccs Towhee software and Molecular dynamic done by DL-POLYsoftware.spc model selected for water molecule. Radial distribution function (RDF) which is important in the theory of simple fluids (gases and liquids) because many thermodynamic quantities can be determined from it, used for pure and doped carbon nanotubes.MOPACquantum chemistry software used for charge distribution in nanotubes.

The Purpose of this Review is to Study the Whole Chemical Mechanisms Happening in the Cooked Foods which Lead to Acrilamid Formation. Learning about These Mechanisms, International Food Safety Experts Found the fact that the Best Program to Reduce Undesirable Effectsof Acrilamid Formation in Foods (Cancer Risk) is to Obligate Food Producers to Improve Product Procedure in Foods Specially the One with Higher Risk of Acrilamid Formation. As a Matter of Fact, Having Proper Knowledge About The Reactions and Effective Components in Acrilamid Formation is Essential to Measure and Control This Mechanisms. According to The Mentioned PointsWe Review The Existence TheoriesAbout Chemical Mechanisms for Acrilamid Formation, FromFree Amino AcidsAnd ReducingSugars, or in Another Chemical ReactionsFormAcrolein and Also Throgh Millard Reaction. Also we Assessed The Effective Factors in ThisReactionsSuch as: pH, Humidity, Temperature and Time of Heating The Results Slow that Comparing With The Other Amino acids, The Asperagin Effective Substance in React With Reducing Sugar Specially (D-Glucose) Which Leads to Acrilamid Formation. Breed and Potato are Rich Sources of Asperagin so Heating and Frying ProcessResult in more Acrilamid Formation in These Kinds of Foods. Consequently The Best Plan to Reduce Acrilamid hazard in Food is to Encourage Food Industries Authorities to Improve Their Technologies in Order to Control Acrilamid Level in Foods. Also All TheMeasuresShould Be Taken to Educate and Recommend Consumers to Have a Balanced Diet.

The zwitterionic intermediate created from the reaction between dichlorocarbene and acetylenic esters is trapped by aromatic aldehydes to afford poly functionalized furans in fairly good yields.

Advanced oxidation processes of of glucose and starch from aqueous solution by using ozone has been studied. A nominal concentration of 100 mgl-1 of the glucose and starch was chosen, which normally occurs in food indusdtry wastewaters. The effect of oxidation concentration and pHon CODand TOChasbeen studied. It wasobserved that the highest removing rate of these factors achieved at alkaline and some neutral conditions, i.e., the indirect mechanism of hydroxyl radical attack on the molecule under study.