1,309 research outputs found

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

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    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

    Comparison of effect of Zataria multiflora and Rosemarinus officinalis extracts on quality of minced frozen silver carp

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    The aim of the this study was to have a comparison between Zataria multiflora and Rosemarinus officinalis extracts on quality of minced frozen silver carp preserved in cold storage temperature -18°C for six months. In this research, one control and three treatments of minced silver carp were prepared as Tr1 (+ Zataria), Tr2 (+Rosemary) and Tr3 (mixed with Rosemary and Zataria) all in normal packaging. After quick freezing of samples in the spiral freezer they were preserved in cold storage temperature -18°C for six months. In this period, the changes of Peroxide Value, Total Volatile Nitrogen, Tio Barbituric Acid and Free Fatty Acids in all treatments were measured based on a predetermined schedule. The results of this investigation showed a significant effect of anti-oxidant in all treatments (p<.05) and it was concluded that Rosemary containing anti-oxidants maintains the best quality after six months of cold storage and corruption indices are not exceeded. Analysis of Peroxide Value, Total Volatile Nitrogen, Tio Barbituric Acid and Free Fatty Acids in different treatments during six months of reservation in freezing under the temperature of -18°C showed that the obtained results to the end of the reservation period for all treatments has increased and treatment containing Rosemary, with Peroxide Value 6.83±0.35meq.1000g^-1, Tio Barbituric Acid 2.1±0.1mgMAL.kg^-1 and Total Volatile Nitrogen with 19.16±0.28mg.100g ^-1 had the best quality of preservation compared with other treatments during the preservation period. Therefore, based on these results and statistical analyses, the effect of anti-oxidant and time in all treatments is significant (p<.05) and the treatments containing Rosemary had the best quality preservation status in -18°C and did not surpass perishing criteria during this period

    Improving workability of cement paste backfill using new binders

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    In this study effects of binder type and content and curing time on the compressive strength development of cement paste backfill (CPB) is investigated. Moreover, the effects of binder type and content and water content on the rheological properties of CPB material were studied. To undertake an experimental study, tailings of a copper mine in South Australia are mixed with binder and water. A new slag-cement called Mine Cement (MC) and ordinary Portland cement (PC) are used as the primary binder materials. Furthermore, fly ash (FA) is used as an additive to reduce the amount of the cement. Some CPB samples were cured under pressure to be more representative of the field conditions. MC exhibited better performance that PC regarding compressive strength development. Fly ash improved the compressive strength of CPB. However, this binder observed to be much less cementitious compare to MC. Strength performance of the CPB sample significantly improved when there were cured under pressure. Based on the results obtained from the test undertaken using a rheometer, it was found that increasing the water content results in lower yield stress. The results also show that MC improves the rheological properties of the CPB

    Crop phenotyping for wheat yield and yield components against drought stress

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    Water deficit is a most limiting factor for wheat in rain-fed agricultural systems worldwide. The effects of drought stress on some root features and yield and yield components in wheat (Trticum aestivum L.) were carried out in a factorial experiment based on completely randomized design, under greenhouse condition. The four experimental irrigation regimes, irrigation after 75% of the water was depleted (control), irrigation after 65% of the water was depleted (mild stress), irrigation after 55% of the water was depleted (moderate stress) and irrigation after 45% of the water was depleted (severe stress) were randomized for the main plots. The subplot treatments included eight wheat genotypes. Results showed that Interaction Drought stress with Variety had significantly affected on Total Root Volume and Dry Matter, Number of Tiller and also Shoot Dry Matter. Value of Total Root Volume and Dry Matter, Shoot Dry Matter and Number of Tiller in irrigated varieties were more than rainfed in whole of Drought stresses. N-87-20 variety had most amounts of Total Root Dry Matter, Total Root Volume (exception of control) in all of stresses and control. Root properties influence on yield and other morphological traits of wheat. Stress intensification increase root growth than plant organ so that wheat root can uptake water from soil to compensate damage caused by stress

    Effects of dietary inclusion of commercial toxin binders and prebiotics on performance and immune responses of broiler chicks fed aflatoxin-contaminated diets

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    This study aimed to evaluate the efficiency of the dietary inclusion of commercial toxin binders (CTs) and prebiotics on growth performance, immune responses, intestinal morphology and blood variables of broiler chicks fed with aflatoxin and non-aflatoxin-contaminated diets. Six hundred one-day-old male Ross 308 broiler chicks, initial weight of 42 ± 3 g, were used in 10 treatments with six replications (n = 10 birds). ASRI1 and ASRI2 commercial toxin binders and lactose prebiotic were included in their diets. Experimental diets included: 1) basal diet without aflatoxin and additives (NC); 2) basal diet containing aflatoxin (PC); 3) NC diet containing ARSI1; 4) NC diet containing ARSI2; 5) NC diet containing prebiotics; 6) PC diet containing ARSI1; 7) PC diet containing ARSI2; 8) PC diet containing prebiotics; 9) PC diet containing ARSI1+prebiotics; and 10) PC diet containing ARSI2+prebiotics. Growth performance, humoral and cellular immune responses, jejunal morphology and some blood variables were assessed. Results showed that broiler chicks fed with a PC diet showed a higher feed conversion ratio and lower body weight in the grower and finisher periods. Broiler chicks fed with PC diets showed lower immunoglobulin G and M and also cellular immunities compared to the NC diet. The PC group also showed lower values for villus length, villus width and crypt depth, and higher values for liver enzyme activities compared to the PC diet. However, dietary inclusion of prebiotics and CTs, in single and combined form, improved growth performance in grower and finisher periods, cellular and humoral immunities, intestinal morphology and the serum concentration of triglycerides, cholesterol, glucose and liver enzyme activities of broiler chicks fed with aflatoxin.Keywords: Aflatoxin, ASRI1 toxin binder, broiler chicks, growth performance, humoral immunit

    Study on effect of Rosmarinus officinalis and Zataria multiflora extracts on the stability of fatty acids in frozen silver carp minced

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    In this study, the effect of Rosemary and Zataria extracts on three different treatments in frozen Silver carp minced were studied in normal packaging. Therefore, a control and three treatments were defined: Treatment 1 - Control: frozen meat packaged in conventional Treatment 2: Frozen Silver carp minced + Zataria 300mg/kg in normal packaging Treatment 3: Frozen Silver carp minced + Rosemary 200mg/kg in normal packaging Treatment 4: Frozen Silver carp minced + Rosemary compound (100mg/kg) and Zataria (100mg/kg) in normal packaging After quick freezing of samples in the spiral freezer by individual quick freezing method, to maintain the cold temperature (-18)°C were transferred. For six month, Sampling and measurements to determine the fatty acid profile of the zero phase beginning in the first month and then every ten days, and 15 days in the second month of the third month after the monthly test. Identifying, defining and measuring the fatty acid profile by gas chromatography was performed. In this study, levels of both saturated and unsaturated fatty acids in three experimental and one control were identified as follows: A: SFA: (Saturated Fatty Acid): Meristic C14: 0/ Palmitic C16: 0 /Hepta decaenoic C17: 0 / Stearic C18: 0 / Arashidic C20: 0 B: (MUFA Mono Unsaturated Fatty Acid): Palmitoleic C16: 1-W7 / Oleic C18: 1-W9 /Gadoleic C20: 1 - W9 C: (PUFA Poly Unsaturated Fatty Acid): Linoleic C18: 2-W6 /α-Linolenic C18:3-W3 D: (HUFA High Unsaturated Fatty Acid): Arachidonic C20: 4 - W6 Eicosa panta enoic acid C20: 5- EPA/W3 Docosa hexa enoic acid C22: 6-DHA/W3. Results of this study was to determine keep frozen fish meat containing extracts of Zataria and Rosemary in freezing conditions, stability of different types of fatty acids, mono unsaturated fatty acids, poly unsaturated fatty acids, high unsaturated fatty acids, So that none of the fatty acids measured, were not observed increase or decrease Changes over time while maintaining the oxidation of fatty acids is minimized. The results obtained from the profile of fatty acids and their related indices and statistical tests show the treatment contains Rosemary extract show greater stability than thyme during storage (- 18)°C. According to studies, Frozen minced fish meat treated with extracts of Rosemary, was used until the end of the storage period

    Tornadoes and related damage costs: statistical modelling with a semi-Markov approach

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    We propose a statistical approach to modelling for predicting and simulating occurrences of tornadoes and accumulated cost distributions over a time interval. This is achieved by modelling the tornado intensity, measured with the Fujita scale, as a stochastic process. Since the Fujita scale divides tornado intensity into six states, it is possible to model the tornado intensity by using Markov and semi-Markov models. We demonstrate that the semi-Markov approach is able to reproduce the duration effect that is detected in tornado occurrence. The superiority of the semi-Markov model as compared to the Markov chain model is also affirmed by means of a statistical test of hypothesis. As an application, we compute the expected value and the variance of the costs generated by the tornadoes over a given time interval in a given area. The paper contributes to the literature by demonstrating that semi-Markov models represent an effective tool for physical analysis of tornadoes as well as for the estimation of the economic damages to human things
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