International Journal of Science
Volume:4 Issue: 2, 2003

The influence of temperature on growth and biochemical constituents of two species of Spirulina; Spirulina platensis and Spirulina fusiformis was studied. Various temperatures as 20, 25, 30, 32, 35, 37 and 400C were investigated. Maximum specific growth rate of 0.141 was found at 320C for S. platensis and that of 0.144 was found at 370C for S. fusiformis. Both species showed negligible growth at 200C and 400C and after 6?8 days culture collapsed. Maximum protein content was found at 320C for S. platensis and at 300C for S. fusiformis and was 59.0 and 62.3 %, respectively. At 370C a significant increase in carbohydrates and in lipids were observed for both species; S. platensis (29.3 and 10.5%) and S. fusiformis (24.3 and 11.0%). Maximum biomass production of 2.4 g l-1 and chlorophyll a production of 16.6 mg l-1 were observed at 320C for S. platensis. Maximum biomass production of 2.3 g l-1 and chlorophyll a production of 14.2 mg l-1 were observed at 370C for S. fusiformis. A net increase in phycocyanin occurred in both species when cultures were grown at the suboptimal temperature of 250C. From the results the optimal growth temperature for S. platensis found at 320C and that for S. fusiformis found at 370C. It can be concluded from the findings that both species are suitable for culture in the tropics.

Myankaleh wildlife refuge is one of the nine biosphere reserves in Man and the Biosphere Program (MaB). Special characteristics of the area make it a suitable habitat for terrestrial and aquatic plants and animals as well as migratory birds. The purpose of this study was to determine floristic composition and their chorology carrying a central importance in vegetation description and analysis. Therefore, about 70 quadrats (100 m2) were located according to the nature of vegetation. The species and their abundance-dominance were recorded. 242 plant species, belonging to 48 families, were identified from which seven were endemic. Chorological characteristics of the plant species showed that most of them were of Euro-Siberian, Mediterranean, Irano-Turanian chorotype (Euro-Sib.-Medit.-Ir.-Tur.). The dominant life form was Therophyte.

Growth of Paracoccus denitrificans bacteria and Candida utilis yeast cells in the presence of increasing concentrations of cadmium led to an inhibition of cell multiplication. P. denitrificans was more resistant to the effect of cadmium than C. utilis. The pattern of cytochrome biosynthesis showed that cadmium inhibited cytochromes b and c synthesis in both organisms. In contrast while cadmium totally inhibited the biosynthesis of cytochrome c oxidase in C. utilis, it had a stimulatory effect on the biosynthesis of this enzyme in P. denitrificans. The comparison of colony size in cadmium–treated cells and in the control showed a remarkable decrease in the colony size of cadmium treated cells. The effect of increasing cadmium concentrations on colony count in Candida utilis showed that from 0.006 to 0.125 mM cadmium the number of colonies was slightly but consistently higher than the control. At 0.25 mM cadmium the number of colonies decreased dramatically, reaching zero for 0.5 mM cadmium. This is the first reported evidence for an inhibitory (in eukaryote) and stimulatory effect (in prokaryote) of cadmium on the biosynthesis of Cytochrome c oxidase. Moreover, our observations provide a better understanding of metal–microorganism interactions for bioremediation of metal contamination of the environment.

The aim of this study was to determine whether an association exists between Epstein Barr Virus (EBV) and esophageal squamous cell carcinoma (ESCC) among Iranian patients. The incidence of the cancer in Iranians is high. EBV has been implicated in a number of human malignancies, many of epithelial origin. The etiology of ESCC appears to involve genetic and environmental factors. Tumerous and histologically normal paraffin-embedded esophageal tissue of 30 patients, and 6 cancerous and 4 non-cancerous freshly frozen tissue specimens of ESCC patients were studied. The samples were evaluated for the presence of EBV by PCR and Southern blot hybridization. The EBV genome was detected in only one non-cancerous specimen. It was concluded that EBV is probably not associated with ESCC among Iranian patients. This is consistent with the results of studies on several but not all other populations. The implications of the geographical variation are discussed.

We present here the results of a formal structure-property relationship study carried out for - and -mediated inhibition of adenylyl cyclase (ADC) by a group of classical cannabinoid derivatives. The wave function was calculated with Zerner’s ZINDO/1 method. Several reactivity indices were calculated from the wave function for a molecular skeleton common to all the molecules. Multiple regression analysis was employed to find the best equation for each case. We found that: (1). the variation of the the cannabinoid-mediated inhibition of ADC is related to the variation of a definite set of molecular reactivity indices, (2). the internal molecular orbitals are extremely important in regulating the cannabinoid-receptor interaction, and (3). the mechanism for the cannabinoid-mediated inhibition of ADC is different for each receptor, involving electrostatic interactions, electron transfer and geometrical substituent effects.

In this work, aluminum electrode was colored with Eriochrom black, using frequency electrochemical noise analysis technique of the FFT impedance response, corrosion resistance of the colored electrode in 0.1 M sulfuric acid solution have been investigated. Scanning Electron Microcopy, also used for monitoring the electrodes surfaces. The electrochemical noise analysis FFT impedance measurements showed that under some applied conditions, coloring aluminum with Eriochrom black could reduce corrosion resistance of aluminum. Where it was realized that application a potential ramp (in ragne of 0 to 3000 mV) produces an oxidation response associated with a significant noise in the FFT spectrum for the colored aluminum. The noise magnitude in the spectrum strongly depends on the applied conditions during anodizing, coloring and sealing stages. The noise analysis of the impedance and SEM images of the surface colored aluminum, showed a correlation between the number of pitting and the noise in the impedance of the surface.

Acritarchs from the Shirgesht, Ghelli and Niur formations were used to determine the age of these rock units and to assess their paleogeographic importance. These formations yielded 55 palynomorph taxa (54 acritarch species and 1 cryptospore species) permitting the recognition of eight biozones (palynozones). The zones I - III represent the Early Ordovician (Tremadocian-Arenigian), zones IV-VI indicate Middle-Late Ordovician (Llanvirian-Ashgillian) and zone VII suggests the Early-Middle Silurian (Llandoverian- early Wenlockian). The presence of genera such as Arbusculidium, Striatotheca and Coryphidium in the Early Ordovician sediments of the Shirgesht Formation from the eastern Central Iran suggest, that the Iranian Platform was part of Peri-Gondwanan Paleo-continent, possibly along the southern shore of the Paleo- Tethys Ocean during the Early Ordovician. Comparison of acritarch taxa from the Ghelli (Middle-Late Ordovician) and Niur (Early-Middle Silurian) formations with those from other parts of the world indicate broad similarity with those of the United States, Europe, North Africa and China. This similarity suggests that the Peri-Gondwanan Paleo-continent began moving northward during the Middle-Late Ordovician and by the Silurian formed part of the supercontinent Pangea. The diverse palynomorph taxa (acritarchs, chitinozoans and scolecodonts) in the Early Ordovician (Shirgesht Formation), Middle-Late Ordovician (Ghelli Formation) and Early-Middle Silurian (Niur Formation) strata indicate a marine depositional environment.

Estimation of shear wave (Vs) velocity using log data is an important approach in the seismic exploration and development of a reservoir. The velocity dispersion due to frequency difference between ultrasonic laboratory measurement on cores and low frequency is about 3.5%, and thus laboratory measurement velocities are more than sonic log in this study. Therefore, we used compressional wave velocity from sonic log to predicate shear wave velocity. In this study, a new statistical method is presented to predict Vs from wireline log data. The model can predict shear wave velocity from petrophysical parameters and any pair of compressional wave velocity, porosity and density in carbonate rocks. The established method can estimate shear wave velocity in carbonate rocks with correlation coefficient of about 0.94.

In this paper we consider the Time Optimal Control Problem with Bounded state (TOCPB). By means of a process of embedding and using measure theory, this problem is replaced by another, in which we seek to minimize a linear form over a subset of a measure space defined by linear equalities. The theory allows us to convert the new problem to an infinite-dimensional linear programming problem. Afterwards, the infinite-dimensional linear programming problem is approximated by a finite dimensional one. Then by the solution of the final linear programming problem one can find an approximate value of the trajectory function, control function and optimal time T as well. AMS classification(49A).