مجله علوم و فنون دریایی
سال بیست و دوم شماره 1 (بهار 1402)

In this study, a sensitive and economical method is suggested for the rapid determination of formaldehyde in seawater samples. This method is based on the reaction of formaldehyde with 5, 5-di methyl-1, 3-cyclohexane dion (dimedone) in the presence of ammonium acetate. After the reaction of derivative, a mixture of 900 µL of ethanol as a dispersive solvent and 100 µL of chloroform as an extraction solvent was rapidly injected into a water sample containing formaldehyde. Their concentrations were determined spectrophotometrically in micro-cuvettes at 395 nm. Under the optimum conditions, the calibration graph was linear in the range of (0.1-100) µg/L with the detection limit of 0.02 µg/L and limit of quantification of 0.07 µg/L for formaldehyde. Parameters affecting extraction efficiency including pH, type and volume of extraction and disperser solvents, and amount of dimedone, were investigated and optimized. Under the optimum conditions, the linearity of the technique was in the range of 0.1-100.0 µg. L-1 with a detection limit of 0.02 µg. L-1 for the same compound. The relative recoveries of formaldehyde from seawater samples at spiking levels of 10 µg. L-1 were between 97.0-99.4%. The proposed method was successfully applied for the determination of formaldehyde in seawater of Chabahar Bay.

Recent advances in electronics and wireless communications have enabled the design and manufacture of sensors with low power consumption, small size, reasonable price and various applications. These small sensors, capable of performing functions such as receiving various peripheral information based on the type of sensor, processing and transmitting that information, have given rise to an idea for the creation and deployment of so-called wireless sensor networks. Due to the unique limitations and unique features of the underwater channel such as low communication bandwidth, high bitrate error, significant propagation delay, etc., these networks can be easily destroyed by malicious attacks. Coordination and transmission of underwater messages between sensors will naturally present security challenges and perspectives. Attack on network protocols, especially communication protocols, can be easily accomplished in underwater wireless sensor networks. Therefore, the purpose of this paper is to present a secure and efficient protocol for communication in underwater sensor networks based solely on lightweight encoder operators with random number generators and cryptographic hash functions. For this purpose, first, a system consisting of a number of sensor nodes and a central node is modeled as receiving information with the presence of nodes or nodes as attackers and then the various steps of the protocol are described in detail. It is further demonstrated that the communication protocol presented in this paper is secure because it is resistant to the all attacks such as message analysis attack, message manipulation attack, relay attack, spoof message injection, insider attack and physical attack. It is also considered as an efficient protocol because it improves communication and computational overheads and memory consumption over previous methods. Statistical tests also show that the encrypted data in the proposed protocol are acceptable randomly and are independent of each other. Finally, in order to make the proposed method more practical in this paper, and to compare the challenges and resources of this method with previous methods for the purpose of hardware implementation, the required cryptographic components are implemented on the FPGA chip.

The transfer of alien and invasive species through the ballast water of vessels is one of the most important threats to aquatic ecosystems.  This study aimed to investigate the ballast water of 10 vessels entering the export port of Majidiyeh Mahshahr in 2018. A sampling of zooplankton from each vessel was performed by filtering 100 litres of ballast water of each vessel using a plankton sampling net with 50 μm mesh with three replications. Simultaneously, environmental factors including dissolved oxygen, acidity, temperature, and salinity were measured with 3 replications in the ballast water of the vessels. The results of a one-way analysis of variance showed that there is a significant difference between the vessels entering the export port of Majidiyeh in terms of the average density of Copepods. The highest average density 3.2×104 ind/m-3 and the number of species (36 species) related to ARGO1 ship from Bandar Abbas and the lowest average density 1×104 and the lowest number of species (24 species) belonged to PRECIGIOUS and GUNISHLI from Fujairah, UAE, respectively. There was a significant positive correlation between the average density of Copepods with temperature and dissolved oxygen. In total, 3 orders, 20 families, 28 genera, and 56 species were identified. All identified species except Oithona davisae have been previously reported from the Persian Gulf. O. davisae species was found only on the CONSTANTINOS ship from the port of Fujairah, UAE. It is native to the coastal waters of East Asia, especially around Japan and China, and has been reported in the Black Sea, the central Mediterranean, and more recently in the Aegean Sea. This research can be important for assessing the potential risk of new invasive species as well as for improving the quantitative and quality management practices of ships' ballast water.

Biofoiling is a problem caused by microbial biofilms. Today, many studies have been done to solve the problems of biofouling. The most important studies have been carried out on the identification of natural antibiotic compounds in the marine environment. The most important studies have been performed on the identification of natural antifouling compounds in the marine environment. In this study, the anti-algae properties of organic and aqueous extracts of (Mentha longifora) were investigated using n-hexane, ethyl acetate, methanol and aqueous solutions. Chlorella vulgaris and Chaetoceros muelleri Microalgae, were grown in F2 culture medium. The extracts were dissolved in a certain amount in DMSO solvent and added to test tubes containing microalgae culture medium in different concentrations. After 24 hours, under a light microscope, the number of algae was counted by a neobar slide. Data were analyzed by SAS program and data were compared by Duncan's multiple range test. Statistical analysis of n-hexane extracts on C. vulgaris and C. muelleri showed that there was a statistically significant difference between the treatments at the probability level of 0.001. Extract of n-hexane with a concentration of (20 mg ml -1) for the microalgae C. vulgaris and for microalgae C. muelleri, an extract of (10 mg ml -1) for the n-hexane had the highest inhibitory.

This research surveys Khorramshahr port solutions about empty container crisis and identifies reasons for adopting strategies and effective factors on it. At first, the researcher attended the Khorramshar container terminal while observed empty container management procedure and interviewing with responsible persons of  Khorrmshahr container terminal and container shipping company Hoopad Darya. During the interviews, the researcher could find information about possible solutions for empty container management. After detecting possible management strategies for decreasing amount of empty container movements and it’s costs, strategies prioritized by aid of industry experts and using AHP method. Finally, the amount of export and trade imbalances recognized as the important factors for accumulation of empty containers. This research based on objective is an applied research and based on nature is mixed research. The results of research shows that the best way of empty container management is creating private yards outside Khorramshahr areas and completing dry port and land transportation of empty containers to Immam Khomayni port. Final part of research is offering applied suggestions.

Emerging economies today see the path of development in expanding their activities towards internationalization. Expanding the boundaries of competition has led businesses to focus more on expanding their operations internationally, and factors such as export performance have become a target for many businesses. In this regard, free zones are dynamic and economic areas that have provided a way to better support businesses by providing support resources. Business networking and the formation of business groups have also created a framework for cooperation and development of competitive capabilities for companies in these economies. To this end, relying on a relationship-based strategic approach, this research examines a set of intra-firm factors, inter-firm factors and external factors were analyzed to examine the export performance of companies operating in the context of the free zone with a network-based perspective (relation view). To fit the research model, a sample of 151 companies active in the Anzali Free Trade-Industrial Zone was selected and surveyed using questionnaire and structural equation modeling technique (using smart PLS software). The results confirm the influence of each of the intra-firm, inter-firm and external factors on export performance. Also, the moderating effect of political relations in the research model was significant only in relation to external factors on export performance, and in other relations it was not confirmed at 95% significance level.

The present study aimed to investigate effects of colored light and tank color on stress response of juvenile beluga, Huso huso, including the measurement of some sero-haematological parameters (Hemoglobin, hematocrit, cortisol, glucose, etc.) and carcass chemical analysis. The study was conducted at International Sturgeon Research Institute in Rasht, Gilan, using 64 specimens for colored light treatments with initial weight 98.83 ± 1.42 (mean ± SE) g which were reared (in groups of 8) under white, red, green and blue light and using 48 specimens for tank color treatments with initial weight 98.46 ± 1.17 (mean ± SE) g which were reared (in groups of 8) in white, black and blue tanks, all for 12 weeks. Based on the obtained results, cortisol levels in fish reared under red and green lights were significantly higher so much so that in addition to stress and light color effects, their interaction was also significant (P< 0.05). The results also depicted that cortisol levels in fish reared in black tank were significantly lower so much so that in addition to stress and tank color effects, their interaction was also significant (P< 0.05). However, in regard to the other parameters- hemoglobin, hematocrit and carcass chemical analysis- no significant differences were observed.  Reviewing the obtained results demonstrates that blue light and black tank by establishing comfort in beluga juveniles have positive significant effects on physiological conditions and spell better stress response.

The viscera of yellowfin tuna (Thunnus albacores) protein hydrolysis was produced using enzymes Flavourzim. Hydrolytic conditions (time, temperature, enzyme to substrate ratio) using response surface methodology (Response Surface Method; RSM) and central composite design (Central Composite Design was optimization). Through these methods, the effects of three factors, temperature, time and amount of enzyme (independent variable) on the degree Hydrolysis as response surface can be studied. The optimized conditions were the ratio of enzyme to substrate of 11/1 Anson units per gram of protein, time 105 min, temperature 93/44 ° C, which brought about the temperature Hydrolysis to 37/23 %. Based on this study which showed that Hydrolysis proteins contain high amounts of protein (45/67 %), it can be concluded that the model predictions are in good condition and protein hydrolysates can be used in fish diets and as additives in the food industry.