Effect of the Heterogeneity of Metamaterials on Casimir-Lifshitz Interaction

The Casimir-Lifshitz interaction between metamaterials is studied using a model that takes into account the structural heterogeneity of the dielectric and magnetic properties of the bodies. A recently developed perturbation theory for the Casimir-Lifshitz interaction between arbitrary material bodies is generalized to include non-uniform magnetic permeability profiles, and used to study the interaction between the magneto-dielectric heterostructures within the leading order. The metamaterials are modeled as two dimensional arrays of domains with varying permittivity and permeability. In the case of two semi-infinite bodies with flat boundaries, the patterned structure of the material properties is found to cause the normal Casimir-Lifshitz force to develop an oscillatory behavior when the distance between the two bodies is comparable to the wavelength of the patterned features in the metamaterials. The non-uniformity also leads to the emergence of lateral Casimir-Lifshitz forces, which tend to strengthen as the gap size becomes smaller. Our results suggest that the recent studies on Casimir-Lifshitz forces between metamaterials, which have been performed with the aim of examining the possibility of observing the repulsive force, should be revisited to include the effect of the patterned structure at the wavelength of several hundred nanometers that coincides with the relevant gap size in the experiments.Comment: 9 pages, 13 figures. Rewriting equations (10) and (12) and increasing the size of the lettering/numeral in figure

Effect of rotifers enriched with betaine and concentrated diet containing betaine on growth, survival and stress resistance of Indian white prawn (Fenneropenaeus indicus)

This study was conducted to investigate the effects of rotifers enriched with betaine and concentrated diet containing betaine on growth performance, survival and resistance to salinity (10 and 5Oppt), temperature (42°C) and formalin (100ppm) stresses in Indian white prawn (Fenneropenaeus indicus) post-larvae. A complete randomized design with three replicates per treatment in nine 20-1 tanks was chosen. Treatments were: Artemia nauplii, rotifers and concentrated diet (control); Artemia nauplii, rotifers enriched with betaine and concentrated diet (treatment 1) and Artemia nauplii, rotifers enriched with betaine and concentrated diet containing betaine (0.8%) (treatment 2). The larvae were fed 6 times per day at 4h intervals. There were significant differences in growth and survival rate between the treatments containing betaine (treatment 1 and 2) and control treatment (P<0.05). Furthermore, the larvae that were fed with betaine (treatment 1 and 2) had significantly higher survival rate in stress resistance testes (P<0.05). The present study showed that betaine has positive effect on growth performance, survival rate and resistance to stresses in Indian white prawn

Identifying the process of national knowledge creation and learning and evaluating its impact on gross domestic product, considering the mediating role of national intelligencee

Background and Objectives: The economic growth of a country depends on several factors, among which the role of knowledge is undeniable. Many studies have shown that countries' GDP is often affected by the country's knowledge infrastructure. A knowledge-based economy is an economy that is directly based on the production, distribution and consumption of knowledge, and investment in knowledge and knowledge-based industries is given special attention. In this economy, where a significant share of GDP is from knowledge-based and knowledge-creating activities, knowledge generates more production than traditional factors such as labor and capital, and the value of many software and biotechnology companies arises from non-physical capitals, i.e. their knowledge and scientific privileges. Accordingly, knowledge creation is an essential weapon in today's world and without a continuous process of knowledge creation, any society is doomed to destruction. Knowledge creation and learning is the creation of new knowledge, or the replacement and improvement of the existing knowledge through social relations and organizational partnerships. The creation and application of knowledge has a major role in increasing wealth in a knowledge-based economy. The problem is that knowledge creation and learning has not been investigated at the national level yet. Methods: By applying qualitative-quantitative methods, based on Delphi technique, the procedure of identifying and explaining the processes of national knowledge creation and learning has been discussed first. Then by using exploratory and confirmatory factor analysis, a significant t-value of more than 1.96, between the identified dimensions and the variable national knowledge creation and learning, was obtained that was acceptable. Findings: Additionally, the impact of the process of national knowledge creation and learning on GDP was measured through conducting a survey and using a questionnaire, while taking the mediating role of national intelligence into account by using Sobel test. It was found that by including the mediating variable of national intelligence, the standardized beta for the relationship between national knowledge creation and learning, and gross domestic product was reduced from 0.80 to 0.18, but it is significant. Conclusion: Therefore, the variable national intelligence plays the role of a partial mediator; in other words, while the impact of national knowledge creation and learning, as the main variable, is maintained, the mediating role of national intelligence also affects GDP. This research had some limitations. One of these limitations was the stereotyped thinking about the process of knowledge creation. In this study, only one dimension of knowledge management, namely ‘knowledge creation’ was used. While we can pay attention to all the processes of the knowledge management cycle in society, instead of just thinking about the creation of knowledge at the national level, in order to promote national performance. Based on this, it is suggested that other researchers consider other dimensions of the knowledge management cycle and go one step further. Researchers can also examine the existing challenges and potential barriers to the national knowledge creation process or the requirements for knowledge creation at the national level. Alternatively, researchers can study international knowledge creation processes by considering cultural differences and provide solutions to increase the likelihood of knowledge creation globally. It is suggested that future researchers make a comparative study of the national knowledge creation model with other models of measuring intellectual capital in the world and examine the strengths and weaknesses of each model and prioritize these models based on their applicability in similar countries. It is also suggested that researchers use fuzzy logic theory to make relative measurements of each of the constructs of the national knowledge creation process and conduct field and academic research in this regard. As another suggestion, researchers can conduct this research on a specific industry and compare its results with the results of this study.   ===================================================================================== COPYRIGHTS  ©2020 The author(s). This is an open access article distributed under the terms of the Creative Commons Attribution (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, as long as the original authors and source are cited. No permission is required from the authors or the publishers.  ====================================================================================

Iron-silver oxide nanoadsorbent synthesized by co-precipitation process for fluoride removal from aqueous solution and its adsorption mechanism

Fe-Ag magnetic binary oxide nanoparticles (Fe-Ag MBON) are prepared with co-precipitation of ferric and ferrous chloride solutions, and used for the adsorption of fluoride from aqueous solution. The surface morphology of the adsorbent was characterized by XRD, SEM, TEM, FTIR, XPS, EDX, BET, DLS and VSM techniques. Batch method was followed to optimize the conditions for the removal of fluoride. The results showed maximum removal occurred at pH 3.0 and adsorption equilibrium was achieved within 20 min. Chemical kinetics of the adsorption were well fitted by pseudo-second order models (R2 &gt; 0.968) and the adsorption process followed the Langmuir isotherm model well (R2 &gt; 0.976). The fluoride adsorption capacity of Fe-Ag MBON was 22.883 mg g-1, and decreased with increasing the temperature. Thermodynamic values revealed that the fluoride adsorption process was spontaneous and exothermic. Regeneration experiments were carried out for six cycles and the results indicate a removal efficiency loss of &lt;22. © 2015 The Royal Society of Chemistry

Static and Dynamic Tearing of Thin Steel Sheets

This paper presents the energy analysis of static mode III fracture of thin steel sheets. For dynamic tearing studies we used the Charpy test apparatus. Static tearing tests performed on three kind steel sheets indicate that the linear relationship of Mai and Cotterell is valid for specimens with a leg width W up to 30 mm. In the given range, the specific work of fracture Te is determined according to the Mai-Cotterell model. The Te kinetics is studied as a function of sheet thickness B, radius of curvature p, and loading rate V. The modified model includes a linear dependence of p versus W. Moreover, we show that variation of loading rate V from 1 to 300 mm/min has no effect on the specific work of fracture Te. A slight decrease in dynamic fracture toughness J0,d is found.Представлен энергетический анализ статического разрушения тонких стальных листов по типу KIII. При динамических испытаниях использовалось оборудование для образцов типа Шарпи. Статические испытания трех видов стальных листов на разрыв свидетельствуют, что линейное соотношение Мая-Коттрелла справедливо для образцов с шириной рабочей части до 30 мм. В указанном диапазоне удельная работа разрушения Ге определяется в соответствии с моделью Мая-Коттрелла. Исследовалась кинетика Ге в зависимости от толщины листа B, радиуса кривизны ρ и скорости нагружения V. Усовершенствованная модель включает линейное отношение ρ/W. Кроме того, изменение скорости нагружения V от 1 до 300 мм/мин показало, что удельная работа разрушения Ге не зависит от нее. Установлено незначительное снижение динамической трещиностойкости J0,d.Представлено енергетичний аналіз статичного руйнування тонких стальних листів за типом KIII . При динамічних випробуваннях використовувалось обладнання для зразків типу Шарпі. Статичні випробування трьох видів стальних дисків на розрив свідчать, що лінійне співвідношення Мая- Коттрелла справедливе для зразків із шириною робочої частини до 30 мм. У такому діапазоні питома робота руйнування Те визначається у відповідності з моделлю Мая-Коттрелла. Досліджувалась кінетика Те в залежності від товщини листа В, радіуса кривини ρ і швидкості навантаження V. Удосконалена модель включає співвідношення ρ/W. Окрім того , змінюючи швидкість навантаження V від 1 до 300 мм/хв, встановлено, що питома робота руйнування Те не залежить від неї. Показано незначне змeншeння динамічної тріщиностійкості J0,d

Performance evaluation of nanocomposit magnetic graphene sheet- iron oxide in removal of nitrate from water using Taguchi experimental design

Background and purpose: Nitrate is one of the chemical water contaminants which can be eliminated through physical, chemical and biological techniques. In this study we aimed for optimization of nitrate adsorption from water onto Magnetic Graphene sheet Nano Particles (G-Fe3O4 MNPs) via Taguchi experimental design. Materials and methods: Batch reactor was used for optimizing of the five parameters (pH, contact time, temperature, adsorbent dosage, and nitrate concentration) at four levels by Minitab software, based on Taguchi experimental design. Signal to noise ratio was used with �the highest is better� approach for optimization of experimental conditions and the highest nitrate removal efficiency. Results: The results revealed that in optimized status (pH=3, contact time= 60 min, initial concentration= 50 mg/L, adsorbent dose= 2g/L, temperature= 50°C) nitrate removal efficiency and adsorption capacity reached 86.4 and 39.37 mg/g, respectively. Contribution percentage of each variable implied that pH and initial concentration of nitrate with 40.20 and 7.49 had the highest and lowest influences on nitrate removal, respectively. Isotherm and kinetic studies illustrated that, nitrate adsorption complied with Langmuir isotherm model (R2>0.993) and pseudo second-order kinetics models (R2> 0.94). Conclusion: G-Fe3O4 MNPs can be used as an effective sorbent for nitrate removal from water or wastewater due to several advantages including easy and rapid separation from solution and high removal efficiency. © 2015, Mazandaran University of Medical Sciences. All rights reserved

The effects of Pediococcus acidilactici as a probiotic on growth performance and survival rate of great sturgeon, Huso huso (Linnaeus, 1758)

This study was accomplished to investigate the effect of Artemia urmiana nauplii enriched with Pediococcus acidilactici as probiotic on growth performance and survival rate of great sturgeon, Huso huso. Artemia nauplii were enriched with P. acidilactici at a final concentration of 10^10 CFU mL^-1 in three time dependent treatments as 3 h (T3), 6 h (T6), 9 h (T9), and one non-enriched Artemia as the control treatment. All treatments were considered in triplicates. Since the nauplii enriched for 9 hours (T9) had the most significant CFU/g compared to other treatments (p0.05). On the other hand, a decreasing trend was recorded in food conversion ratio (FCR) and final biomass changed significantly for T9 in comparison with that recorded in the control group (p<0.05). The results indicated that P. acidilactici had a positive effect on growth and survival of beluga larvae, and a different time of enrichment had a significant effect on LAB effect. The best time of enrichment for beluga larvae was found to be 9 hours

New food diet formulation for rearing and propagation in white worm (Enchytraeus albidus Henle, 1837)

In this study, 4 different food diets were examined for feeding white worm (Enchytraeus albidus Henle, 1837) which is used as the most important live food for fingerlings sturgeons were studied. Results showed that suitable moisture for growth and development of white worm was 50 - 70 % that their biomass reached to a 675 g/m^2 during 90 days. But it decreased significantly at moisture lower than 45 % and upper than 65 %. White worm had similar growth both in acidic and basic area. White worm biomass reached to 576g/m^2 during 90 days in basic area but reached to 568 g/m^2 in acidic that was maximum at pH 6.4 - 7.6, while its growth decreases at pH lower than 6 and higher than 8. In this study, Azola used as food for white worm in amount of 60%, wheat meal 25%, and wheat bran 15% that caused to more growth in worms and their biomass reached to 533 g/m^2 during 90 days. Although biomass of worm fed with mixture of potato 30%, carrot 3%, wheat meal 25% and wheat bran 15% reached to 584 g/m^2 , but biomass of worms were fed with mixture of potato 60%, wheat meal 25%, and wheat bran 15% reached to 576 during 90 days. Economically, cost production of Azola was lower in comparison to other diets. Biochemical decomposition of worms fed with mixture of Azola, wheat meal and wheat bran showed more protein (33 %) than others. Based on results Azola can be used as a suitable and commercial replacement for white worm food diets

Influence of trout farm effluents on water quality parameters and benthic macroinvertebrates

The aim of this study was to assess the influence of trout farm effluents on water quality parameters in the Dohezar Stream. In this study two trout farms and 7 stations were selected and physiochemical of water, including air and water temperatures, dissolved oxygen concentration (DO), pH, electrical conductivity (EC), water flow and biochemical oxygen demand (BOD) were measured every 30 days for one year. A combined total of 60 benthic macroinvertebrate taxa were collected from the seven sites of the stream. The results showed that trout farms had a significant impact on EC, pH, water flow and BOD in the water throughout the year and among stations (p<0.05). Only DO did not show significant differences in the one year survey. Macroinvertebrates had significant differences in abundance downstream from the trout farm effluent, particularly in stations 1 and 3 compared with others. However, the diversity of benthic macroinvertebrates significantly decreased, particularly in stations of 3, 4, 6 and 7. Regarding benthic macroinvertebrates, the abundance percentage of ephemeropterans, plecopterans and trichopterans (expressed as EPT %), and Biological Monitoring Working Party (BMWP) were much lower in station 3 than in other stations

Prediction of the critical stress to crack initiation associated to the investigation of fatigue small crack

Fatigue design is of vital importance to avoid fatigue small crack growth in engineering structures. This study shows that the critical fatigue design stress can be defined below the usual endurance limit, considered inrules and codes. The material constitutive behaviour is using linear isotropic elasticity.Lassere and Pallin-Luc [1-2] use the elastic energy and over-energy under uniaxial load (tension and rotating bending). The authors deduce the influencing critical stress value corresponding to sigma star. It’s a linear approach.We propose an over-energy under dissymmetrical rotating bending and expressed in the ellipse axes. An asymptotic approach is transformed the over-energy in polynomial function of critical stress. Unknown depend on experimental service conditions, endurance limit of tension and rotating bending of specimen. The fatigue database of 30NCD16 steel studied by Froustey and Dubar [3-13] is used. Critical stresses are evaluated (Fig. 2).The research done by Manning and all [4] has shown the small crack effect to be as large as 0.3 mm. Small crack and critical stress are illustrated here in as resulting from pure bending approach expressed by Bazant law [7]. It’s reproduces well the Kitagawa diagram [6] (Fig. 3). When the short cracks are hidden in the material, we shows that the number&nbsp; cycles during small crack growth be significantly higher (Fig. 4) than the corresponding cycles of large cracks growth (ONI’s fatigue test) for the same physically crack size. Indeed its evolution can be blocked by a microstructural barrier (grain boundary, for example). Hence, the considerations of small crack growth are strongly influencing the fatigue life of a component or structure