JOURNAL OF SCIENCES (ISLAMIC AZAD UNIVERSITY)
Year:2008 | Volume:18 | Issue:68 (CHEMISTRY ISSUE)|Papers Count:10

Fractal analysis of the morphology of ice crystal particles in frozen food was attempted for frozen soybean curd (tofu). From a microscopic image analysis of the ice crystal particles, it was found that the perimeter of the ice crystal particles could be recognized as a fractal. Effects of the storage time and storage temperature on the fractal dimension (dp) of the perimeter of the ice crystal particles were also investigated. Fractal dimension (dp) could be used as a quantitative indicator reflecting the surface roughness of ice crystal particles.

The shoots of Ribes bibersteinii were collected from one of the natural habitats,i.e, Damash - Roodbar highlands. Essential oils were extracted by water distillation after scientific name confirmation. The oil yield was 0.038 %. The essential oils were analyzed by GC and GC/MS. 14 compounds were identified that the major volatiles were Hexadecanoic acid (56.35%), Tetradecanoic acid (10.47%), Dodecanoic acid (5.68%) and Beta-Ionone (5.30%).

One of the most important applicable nanoparticles is gold nanoparticles which are of prime important in nanobiotechnology. Therefore, it is important to find out/use suitable techniques to prepare nano particles of different sizes and shapes for various applications. In this article, we have prepared gold nanoparticles by Chemical reduction method employing L-phenylalanine as a reducing agent for ionic gold. In this study, HAuCl4 .3H2O, L- phenylalanine and sodium dodycel sulfate (SDS) were used as pre-material, reducing and stabilizing agents respectively. The size, distribution and formation of gold nano particles were confirmed by transmission electron microscopy and dynamic light scattering indicating the diameter of gold nanoparticles at the range of 5-20nm. The formed nanoparticles showed the highest absorption at 533nm by UV-Vis spectroscopy. The gold nanoparticles were stable for one week in the absence of stabilizer and were stable for 21 days in the presence of stabilizer.

Flavonoids, the most important of secondary metabolism products, occur in the plants. They have medicine and biological effects such as: Purifies blood, strengthens immune system, monitors cholesterol level, regulates blood pressure, suppresses acid secretion, prevents thrombus, suppresses cytophy, antibacterial, prevents cancer, promotes metabolism.In this study, the flavonoids of methanolic extract from Chrysanthemum parthenium (syn. Tanacetum parthenium) (Compositae Family) were separated and purified by column chromatography and TLC methods. Flavonol ، Kaempferol ، Fisetin and Naringenin are four flavonoid compounds were extracted, separated and detected by spectroscopy methods (1H-NMR, 13C-NMR, Mass and IR.

Humulus Lupulus L. (Hop) is a dioecious and perennial plant of Cannabaceae that important medical and industrial plant in the world, which has traditional uses in treatment insomnia, restlessness, nervous tensions, irritability, charleyhorse, etc. The reportage antibacterial and antifungal effects and potentially giving them anticancer of plant.There is a method for determining of alfa and beta-acids for medicinal uses of hops extracts in pharmacopeias such as BP and USP, but it takes more times and has low precision and accuracy in analysis data. Thus it is useless for many industries. 2-Methyl-3-buten-2-ol, myrcene and alfa-humulene are three main constituents in essential oil part of Hops extracts were determined in the extract directly as simultaneous analysis.The method was based on internal standard by Gas chromatography. Determined amount of the extract was shaking with determined amount of dichloromethane and after separation of the dichloromethanic phase, the internal standard was added and injected to a temperature programmed GC. Concentration of main fractions like as 2-Methyl-3-buten-2-ol, myrcene and alfa-humulene were determined by internal standard method and with calibration curve of each substance. The method was validated and used for comparing some Iranian and other countries Hops extracts. This study revealed that the concentration of 2-methyl-3-buten-2-ol, myrcene and alfa-humulene in Hops extract was 12.6, 30.6 and 2.5 mg/100ml respectively , also considering validation percentage of precision 2.8%, 3.9% and 29.9% respectively.

A quantitative structure-activity relationship (QSAR) study is suggested for the prediction of retention time of volatile organic compounds in waste water. Modeling of the retention time of volatile compounds as a function of molecular structures was established by means of the chemometrics methods such as partial least squares (PLS) and least squares support vector machines (LS-SVM). These models were applied for the prediction of the retention times of these compounds, which were not in the modeling procedure. The predictive quality of the QSAR models were tested for an external prediction set of 8 compounds randomly chosen from 59 compounds. The resulted model showed high prediction ability with root mean square error of prediction of 0.0335 for LS-SVM.

Six new polyamides 5a-f were prepared by direct polycondensation reaction of 4-phenylenediacrylic acid 3 with six aromatic diamines 4a-f by using thionyl chloride and pyridine as condensing agents in N-methyl-2-pyrolidone (NMP) as solvent. These new polymers 5a-f were obtained in high yield and inherent viscosity between 0.30-0.50 dL/g. The resulting polyamides were characterized by elemental analysis, viscosity measurements, thermal gravimetric analysis (TGA and DTG), solubility test, FT-IR and UV-vis spectroscopy. 4-Phenylenediacrylic acid 3 was prepared by the condensation reaction of terephthal aldehyde 1 with malonic acid 2 in the presence of pyridine.

NBO analysis, density functional theory (DFT: B3LYP/6-31G*// B3LYP/6-31G*) and ab initio molecular (MO: MP2/6-31G*//B3LYP/6-31G*) based method were used to investigate the structural optimization and configurational properties of cycloocta-1, 3, 4, 6- tetraene (1), cycloocta-1, 2, 4, 6-tetraene (2), cyclonona-1, 2, 4, 6, 7-pentaene (3), cyclonona-1, 2, 4, 5, 7-pentaene (4) and cyclodeca-1, 2, 4, 5, 7, 8-hexaene (5), which could be obtained by adding Csp atoms into C=C double bonds of cyclohepta-1, 3, 5-triene.The NBO analysis of donor-acceptor (bond-antibond) interactions revealed that there is no any correlation between the S(p®p*) resonance energies and the order of the stability of the various configurations of compounds 1-5, however, NBO results revealed that the sum of p and s bonding orbital deviations (SpDev+SsDev) increases from the most stabe form of compound1-5to their relative unstable forms.The relative stability of various configurations of compounds 1-5 could fairly be explained by the Ssdev and Spdev values.

Molecular similarity and quantitative structure property relationship (QSPR) analyses have been used to develop compact, robust, and definitive models for essential oils compounds. The QSPR models have been sought to provide an interpretation and characterization of retention index of essential oils. A training set of 66 structurally diverse compounds were selected to be representative of a parent set of 86 compounds and range in measured retention index. In order to evaluate the models, we chose another set with 20 molecules as a prediction set. Descriptors derived from semiempirical (AM1) molecular orbital calculations have been used to construct a QSPR for the retention index, RI, of a series of essential oils. Root mean square error of prediction (RMSEP), average relative error (REP %) and R2 of prediction set for were about 0.011, 0.372 and 0.976, respectively.