General methods for designing single-mode planar photonic crystal waveguides in hexagonal lattice structures

We systematically investigate and compare general methods of designing single mode photonic crystal waveguides in a two-dimensional hexagonal lattice of air holes in a dielectric material. We apply the rather general methods to dielectric-core hexagonal lattice photonic crystals since they have not been widely explored before. We show that it is possible to obtain single mode guiding in a limited portion of the photonic bandgap of hexagonal lattice structures. We also compare the potentials of different photonic crystal lattices for designing single-mode waveguides and conclude that triangular lattice structures are the best choice

Growth performance, carcass composition, and immunophysiological indices in juvenile great sturgeon (Huso huso) fed on commercial prebiotic, Immunoster

Growth performance, carcass composition, and immunophysiological indices in juvenile great sturgeon (Huso huso) fed on commercial prebiotic Immunoster (IS) were investigated. After a four-week acclimatization period, 270 great sturgeon juveniles weighing 95.68 ± 10.05 g were randomly distributed into 9 fiberglass tanks in three replicates and kept at a density of 30 fish per tank for a period of 8 weeks at water temperature 20.55 ± 5.11ºC and dissolved oxygen 6.73 ± 0.35 mg L^-1. IS was added at two levels of 1% and 3% to the basal diet in place of cellulose. At the end of the trial, blood sampling and carcass analysis were conducted. Weight, length, body weight increase (BWI), specific growth rate (SGR), feed conversion ratio (FCR), protein efficiency ratio (PER) and condition factor (CF) were significantly affected by IS 3% compared with IS 1% and the control (P<0.05). There was significant difference (P<0.05) in crude protein of carcass between the experimental groups. Mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH) showed significantly higher levels in experimental treatments compared with the control (P<0.05). Immunoglobulin M (IgM) level and lysozyme activity in IS 1% group were higher than the control group. It can be concluded that IS can enhance growth performance and improve some immunophysiological indices of great sturgeon

Study of anaesthetic effects of clove oil (Eugenia caryophyllata) in common carp (Cyprinus carpio) under various pH and temperature condition

The anaesthetic effects of clove oil in juvenile common carp (8-12 g) were investigated under various water quality conditions, consisting of different pH and temperature. The time to loss the equilibrium, induction of anesthesia, equilibrium recovery and response recovery were measured. The results showed that clove oil induced the desirable anaesthetic condition in less than 3 minutes in all experiments. However the time of equilibrium recovery and response recovery were longer than 5 minutes in many cases. When using clove oil at concentration of 100ppm, the most suitable anaesthetic effects and recovery times were observed at water temperature of 25֯ C and pH=7 and 8,as well as at 30֯ C with pH=9. No morbidity or mortality occurred during induction of anesthesia by clove oil and recovery of fishes

Species identification reveals mislabeling of important fish products in Iran by DNA barcoding

This study reports on the molecular identification of fish species from processed products which had a priori been classified as belonging to 5 important species in Iran for human consumption. DNA barcoding using direct sequencing of an approximately 650bp of mitochondrial Cytochrome oxidase subunit I (COI) gene revealed incorrect labeling of Narrow-barred Spanish mackerel samples. High occurrence of fraudulent fishery products, if left unchecked, can pose a negative impact on the economy. This investigation adds further concern on the trading of processed fish products in Iran from both health and conservation points of view

The effect of gut microbiota and probiotics on metabolism in fish and shrimp

The present paper presents an overview of the effects of gut microbiota and probiotics on lipid-, carbohydrate-, protein- and amino acid metabolism in fish and shrimp. In probiotic fish studies, the zebrafish (Danio rerio) model is the most frequently used, and probiotic administration reveals the effect on glucose homeostasis, anti-lipidemic effects and increasing short-chain fatty acids, and increased expressions of genes related to carbohydrate metabolism and innate immunity, along with down-regulation of oxidative stress-related genes. Further, improved length of the intestinal villi and expression of nutrient transporters in fish owing to probiotics exposure have been documented. The present review will present an appraisal of the effect of intestinal microbiota and probiotic administration on the metabolism of nutrients and metabolites related to stress and immunity in diverse fish- and shrimp species. Furthermore, to give the reader satisfactory information on the topics discussed, some information from endothermic animals is also presented

3D printing on-water sports boards with bio-inspired core designs

Modeling and analyzing the sports equipment for injury prevention, reduction in cost, and performance enhancement have gained considerable attention in the sports engineering community. In this regard, the structure study of on-water sports board (surfboard, kiteboard, and skimboard) is vital due to its close relation with environmental and human health as well as performance and safety of the board. The aim of this paper is to advance the on-water sports board through various bio-inspired core structure designs such as honeycomb, spiderweb, pinecone, and carbon atom configuration fabricated by three-dimensional (3D) printing technology. Fused deposition modeling was employed to fabricate complex structures from polylactic acid (PLA) materials. A 3D-printed sample board with a uniform honeycomb structure was designed, 3D printed, and tested under three-point bending conditions. A geometrically linear analytical method was developed for the honeycomb core structure using the energy method and considering the equivalent section for honeycombs. A geometrically non-linear finite element method based on the ABAQUS software was also employed to simulate the boards with various core designs. Experiments were conducted to verify the analytical and numerical results. After validation, various patterns were simulated, and it was found that bio-inspired functionally graded honeycomb structure had the best bending performance. Due to the absence of similar designs and results in the literature, this paper is expected to advance the state of the art of on-water sports boards and provide designers with structures that could enhance the performance of sports equipment

Toxicity comparison of colloidal silver nanoparticles in various life stages of rainbow trout (Oncorhynchus mykiss)

Recognizing the significance of the life stage of fish for nano-eco-toxicological studies, the acute toxicity of colloidal silver nanoparticles (AgNPs) was tested in three different life stages of rainbow trout. Fishes were exposed to colloidal AgNPs at nominal concentrations of 100, 32, 10, 3.2, 1, 0.32, 0.1, and 0.032 mg/L. The estimated 96 hr LC50 values were 0.25, 0.71, and 2.16 mg/L for the eleutheroembryos, larvae and juveniles, respectively, revealing a higher sensitivity for the early life stages. In addition, a dose-dependent blood plasma reduction of chloride and potassium, also increase of cortisol and cholinesterase were observed in the juveniles to exposed AgNPs when compared to the controls. Thus, colloidal AgNPs should be classified as ‘very toxic’ and ‘toxic’ to the eleutheroembryo-larva and juvenile stages, respectively, meaning that the release of nanosilver into the aquatic environment or its direct application as an antimicrobial agent in aquaculture should no longer be allowed