A study of reactive ion etching of gallium arsenide in mixtures of methane and hydrogen plasmas

The aim of this research was to investigate the reactive ion etching (RIE) of gallium arsenide (GaAs) in mixtures of methane and hydrogen (CH ₄H₂) plasma and to evaluate thier advantages over chlorinated plasmas. This was performed in order to find the optimum etching conditions for GaAs such as, the best etch rate with greatest degree of anisotropy, the finest smooth side walls and the lowest surface roughness. The induced damage to GaAs due to RIE was investigated by current-voltage (I-V) and capacitance-voltage (C-V) measurements. From a study of the behaviour of the DC self bias voltage and an analysis of electrical characterization, a possible model of the mechanism of etching GaAs in methane and hydrogen mixtures was proposed. The main contributions of this research are as follows: Etching of GaAs while maintaining the total flow rate of the gas mixture and its residence time in the chamber constant. Studying the effect of the physical component of the etching mechanism on GaAs by investigating the variation in the DC self bias voltage for all process parameters. Analyzing the effect of process parameters on the deposition rate of carbon polymers on the surface of the inorganic mask during GaAs etching. Investigating the effect of process parameters and carbon polymer deposition on SiO ₂mask erosion during GaAs etching. Examining the electrical characteristics of highly doped p-GaAs following RIE in CH ₄/H₂ plasma and comparing with those of H ₂ etched samples

Feeding behaviour of blue swimmer crab (Potunus pelagicus) in Hormuzgan province waters

This research was carried out to study the feeding behaviour of blue swimmer crab (Portunus pelagicus) in Hormuzgan province waters from October 2001 to December 2002. Samplings were done in different methods by presence on research vessels, fishing vessels and dhows in addition to collect the samples from stake-nets. 490 stomach contents were observed under stereomicroscope in which among them the numbers of full, semi-full and empty stomachs were 136,197 and 157, respectively. The food contents were classified into 4 main groups namely; fish, mollusc, crustacean and plankton. The Index of C.V. was estimated 32.04. This figure shows that blue swimmer crab can be assumed as a gluttonous species

The reproduction biology of Abudefduf sexfasciatus in the Persian Gulf (Larak Island)

The reproduction biology of A. sexfasciatus, one of the main and important ornamental fishes in the Persian Gulf were studied during 1997-98. For sampling, Larak island sited on south-eastern of Bandar-Abbas was chosen. The main fishing gear was hook for collecting samples. During this investigation, weight, length (FL & T.L), GSI, HSI, Kf, sex ratio, LM50 and sexual overlap zone were measured or calculated. Also, the histological studies were done on gonads. The results showed that this species is a protogenous hermaphrodite. A. sexfasciatus has an allometric growth and the results of GSI, HSI and Kf indicated that the spawning season occured in spring as a total spawner species. The sex ratio was found M:F=1.00:1.24 without any significant difference. The overlap zone was recongnized 30mm (with a range of 125-155mm). The LM50 was calculated 130-140mm for females and 160-170mm for males. The size at first maturity for females and males were determined 105 and 120mm, respectively

Identification of marine ornamental fishes in northern part of the Persian Gulf, Iran

In the past decade, the investment in fisheries development has grown remarkably in the Persian Gulf region. A 1800 km of northern coastline of the Persian Gulf, the Oman Sea and more than 14 islands belong to Iran have provided great possibilities of economic activities. In-shore marine islands such as Kish, Farour, Hendurabi, Tonb made a good opportunity for fishing and harvesting of ornamental fishes living on coral reefs. The Kish island have a plenty of coral reefs in around. The study was conducted on the Kish islands to identify various species of reef fishes on October 1997 to November 1998. Experiment was carried out at 77 stations around the islands. Samples were collected by underwater purse_seining, scuba diving, and using anesthetizes by injection around the fish hiding area. Results conducted that overall 113 species belong to 47 families were identified of which Pomacentridae, Acanthuridae, Scaridae and Lutjanidae are the most important in terms of number of species represented. 4 species of Apogonidae, 6 species of Lutjanidae, 11 species of Pomacentridae, 6 species of Nemipteridae, 6 species of Serranidae, 3 species of Teraponidae, 3 species of Sparidae, 3 species of Scorpaenidae, 3species of Scaridae, 3 species of Lethrinidae, 4 species of Labridae, 4 species of Gobiidae, 4 species of Chaetodontidae, 4 species of Carangidae, 2 species of Belonidae, 2 species of Balistidae, 2 species of Acanthuridae, 2 species of Tetraodontidae, 2 species of Siganidae, 2 species of Ostraciidae, 1 species of Monacanthidae, 1 species of Leiognathidae, 1 species of Atherinidae are the species presented in coral reefs at Kish island

The effects of phytoestrogens Matricaria recutita on growth, maturation of oocytes in the three spot gourami (Trichogaster trichopterus)

Chamomile is a rich source of phytoestrogens; these compounds have antioxidant, anticancer. In this study, the effects of chamomile on growing oocytes in immature female gourami fish were examined. Thus 60 immature female gourami fish with an average weight of 2-3 g of 6-treated group were analyzed. Treatments in a completely randomized experimental design with a dose of chamomile (10-20-30-50 mg/kg fish) along with control (no injection) and ethanol control (solvent injection) and with three replicates were tested. The fish adaptation to the environment lasted 3 days. The extract injections were done for 20 days, in 10 periods, every other day. In order to histological study, three days after end of the experiment, the ovarian tissue was removed and weighed, tissue processing and staining steps done with hematoxylin- eosin. At last the histological structure of the ovaries and the average percentage of treated fish gonadal indices were compared with the control group. According to our results of gonadal index, there was no significant difference between the control groups with receiving Ethanol (p>0.05). Histological results showed that increasing the dose of chamomile extract accelerate oocyte maturation in three spot gourami. This is the fourth treatment (dose, mg / kg 50) to show its obvious. The difference between oocyte diameter was observed with increasing doses of Chamomile and in comparison with the control group, the difference was significant (p <0.05). Histological results showed that increasing the dose of Chamomile accelerate oocyte maturation in three spot gourami

Effects of different salinity on number and area of chloride cells in gill of juvenile grouper (Epinephelus coioides)

The purpose of this study was to evaluate the ability of osmoregulation by mitochondria-rich cells in grouper fish with high tolerance of salinity variation levels. For this purpose, groupers were transferred from salt water with an average salinity of 40 ppt to the waters with 10 ppt, 20 ppt and 60 ppt rates of salinity. Changes in the number and area of chloride cells in the different treatments were observed during two months adjustment period. Experiment was carried out by sampling three fish from each tank within 8 phases at the moment of the transition, 12 hours, day 1, day 3, day 7, day 14, day 30 and day 60. Histomorphological and immunohistochemical observations were done after fixing in Bouin's solution for 24 hours. Samples were dehydrated with increasing series of ethanol, followed by paraffin, and cleared by xylene. Paraffin blocks were cut at 5 microns and stained by hematoxylin – eosin. Changes in the number and area of chloride cells in 5% level were very different at high and brackish salinity. So in the early hours of the transfer, number and area of chloride cells were low in the brackish water than to that in high salinity. From second week towards the end of period, number of chloride cells in 60 ppt was more than that in control treatment from seventh days towards the end of period, the area of chloride cells was more than that in control group. The high ability and adaptability of this species in response to different environmental salinities might be associated with changes in gill histological evaluation and model osmoregulation mechanisms at different salinities

Effect of 17- alpha- methyl testosterone on cichlid kaliko (Labeotropheous foellobroni) sex reversal

In this present study, Cichlid Kaliko (Labeotropheous foellobroni) fallowing was exposed to 17-alpha-methyl testosterone at 2 stages of development including prior to maturity (larvae) and after puberty (broodstock). The influence of sex hormone on the larvae was also explored. The first group was the larvae under the four treatments (0, 50,100, 250) mg per kg of food and hormones that broodstock group also included four treatments (0, 100, 250, 400) mg per kg food three replicates were performed in a period of 30 days. Hormone was added to fish food. Results showed that treatments had a significant difference in fish growth, which correlated with increased amounts of 17 alpha-methyl testosterone. In group I, food with 250mg/kg testerone resulted in an increase in growth indices (i.e.s, SGR=1.4, ADG= 6.5) with a mortality rate of 48.3 percent. In group II results showed that treatment of G (400mg testosterone per kg food) produced larvae with maximum growth indices (SGR=0.91, ADG= 3.6) and the least mortality rate of 31 percent; Research revealed that 17 alpha methyl testosterone could have an effect on Calico fish sex changes in both larval and stock stages

A study on growth parameters, blood factors and proximate composition of rainbow trout (Oncorhynchus mykiss) cultured in underground brackish and freshwater

In this research, growth rate, blood parameters and proximate composition of rainbow trout (Oncorhynchus mykiss) cultured in brackish and freshwater were evaluated. Two treatments (brackish and freshwater) in 3 replications were investigated. Six 1.5 m³ fiberglass tanks were used for this experiment, containing 180 rainbow trout specimens with average weight of 47.2±0.1g. Feeding rate in treatments was about 3% of body weight based on water temperature and fish biomass. Total length and weight of fish were measured in 15 days intervals. After 135 days of culture period, some fish samples were transferred to the Lab. Blood were directly collected from the heart. Muscle composition was analyzed for proximate composition. The results showed that the body weight of samples in brackish water was increased significantly after 45 days of culture period. Blood factors including WBC, RBC, Hb, Hct, MCV, MCH, MCHC, lymphocyte, thrombocyte and concentration of K+ ions in fish cultured in brackish water showed a significant increase (P<0.05). Muscle composition analysis showed a significant increasing (p<0.05) in fat and dry matter in freshwater treatment, while moisture was significantly higher in brackish water (P<0.01)

Effects of LHRH-A2 and chlorpromazine (dopamine antagonists) on inducing spawning in Caspian Kutum, Rutilus frisii kutum, from the southwest of the Caspian Sea

Caspian kutum, Rutilus frisii kutum, is one of the most commercially important fish species in the Caspian Sea, but there are few reports about the endocrinology of induced spawning in this fish. In the present study, 54 individuals of female broodstocks of Kutum were studied for quantity and quality of propagation index, during March and April 2007. Hormone treatments include: LHRH-A2 (1 µg kg-1bw;chlorpromazine (2.5 mg kg-1bw); LHRH-A2 + chlorpromazine (1µg kg-1bw+2.5 mg kg-1bw); CPE as a positive control (1 mg kg-1bw); Physiological saline as a negative control; and normal brood stocks without injection. For histological examinations, ovarian samples of non-ovulated females were fixed in bouin's fluid. The routine procedures of preparation of tissues were followed and the paraffin blocks were cut at 5-7 microns, stained with H&E and studied under light microscope. The results showed that the highest percentage of ovulated females belonged to group 1 without significant difference with positive control.There was a significant difference between ovulated females in the LHRH-A2, chlorpromazine and LHRH-A2 + chlorpromazine treatments (P0.05). Chlorpromazine could not be a potent dopamine antagonist and the microscopic observations of ovary in non- ovulated brood stocks showed that the oocytes in these treatments were in the final phase of IV stage

Hormonal sex reversal of rainbow trout (Oncorhynchus mykiss) by ethynylestradiol-17α (EE2)

Rainbow trout (Oncorhynchus mykiss) females grow larger and mature later than males, making all-female stocks economically advantageous. The objective of this research was to develop methods for the production of monosex populations of trout through the use of sex steroids. The synthetic estrogen ethynylestradiol-17α (EE2) was administered in single period-immersion treatment of 400 µg/l for 1, 2, 4 and 8 h to groups of newly-hatched sac fries of rainbow trout and in a 30 day dietary treatment of 5, 10, 15 and 20 mg/kgf of newly swum up fries. 73.4 And 94.5% females were obtained with 1 and 2-h single-immersion of EE2 respectively (38% female in control). However, higher doses progressively reduced the survival drastically. Sex ratios of dietary treatment of fry were 60, 57.4, 78 and 94% females respectively. Treatments also resulted in a slight increase of both weight and length. This increase was related to the method of hormonal exposure (dietary > immersion), but not dosage-dependent for utilized hormone. This demonstrates that the direct feminization of rainbow trout can be achieved and resulted in sex reversal ratio effectively but not decreased the growth, as observed in hormonal sex reversed females, and it would be a noticeable approach to the direct feminization of trout