On the acoustic levitation stability behaviour of spherical and ellipsoidal particles

We present here an in-depth analysis of particle levitation stability and the role of the radial and axial forces exerted on fixed spherical and ellipsoidal particles levitated in an axisymmetric acoustic levitator, over a wide range of particle sizes and surrounding medium viscosities. We show that the stability behaviour of a levitated particle in an axisymmetric levitator is unequivocally connected to the radial forces: the loss of levitation stability is always due to the change of the radial force sign from positive to negative. It is found that the axial force exerted on a sphere of radius ${R}_{s}$ increases with increasing viscosity for ${R}_{s} / \lambda \lt 0. 0125$ ( $\lambda$ is the acoustic wavelength), with the viscous contribution of this force scaling with the inverse of the sphere radius. The axial force decreases with increasing viscosity for spheres with ${R}_{s} / \lambda \gt 0. 0125$ . The radial force, on the other hand, decreases monotonically with increasing viscosity. The radial and axial forces exerted on an ellipsoidal particle are larger than those exerted on a volume-equivalent sphere, up to the point where the ellipsoid starts to act as an obstacle to the formation of the standing wave in the levitator chambe

Magneto-optical study of thermally annealed InAs-InGaAs-GaAs self-assembled quantum dots

We report a magneto-optical study of InAs-InGaAs-GaAs self-assembled quantum dots (QDs) subjected to post-growth thermal annealing at different temperatures. At low temperatures annealing strongly affects the bimodal distribution of QDs; at higher temperatures a strong blueshift of the emission occurs. Magnetophotoluminescence reveals that the annealing increases the QD size, with a larger effect occurring along the growth axis, and decreases the carrier effective masses. The main contribution to the blueshift is deduced to be an increase in the average Ga composition of the QDs. The inadvertent annealing which occurs during the growth of the upper AlGaAs cladding layer in laser structures is also studied

Survey of abundance and distribution of rocky shore Polychaeta from the Hormonz Island in Persian Gulf

Polychaeta are the most important benthic animals and consist of many species with a vital role in food web. We conducted a survey from summer 2005 to spring 2006 to complete the ecological studies of macrobenthos in rocky shores of the intertidal zone of the Hormouz Island. Three main regions were studied in the west, south and south-eastern parts and three transects were sampled in each region to test variation in Polychaeta distribution and abundance along the entire intertidal zone. At each one of the nine transects the shore was levelled and a general qualitative description was made, which also aided in the stratification of subsequent quantitative sampling. Samples were fixed in %4 formalin and transported to lab for analysis. Results showed presence of 10 genera of Polychaeta among which Nereis was the most abundant in the intertidal rocky shores. Our study also revealed seasonal and zonal distribution of Polychaeta in rocky shores of the area. Abundance of Polychaeta was markedly higher in summer compared to winter and in the upper zone compared with the mill-littoral zone. Results of Shannon and Simpson diversity indexes affirmed above conclusion

CO2-brine-rock interactions: The effect of impurities on grain size distribution and reservoir permeability

The Bunter Sandstone formation in the UK’s southern North Sea has been identified as having the potential to store large volumes of CO2. Prior to injection, CO2 is captured with certain amounts of impurities, usually less than 5%vol. The dissolution of these impurities in formation water can cause chemical reactions between CO2, brine, and rock, which can affect the reservoir quality by altering properties such as permeability. In this study, we explored the effect of CO2 and impurities (NO2, SO2, H2S) on reservoir permeability by measuring changes in grain size distributions after a prolonged period of 9 months, simulating in situ experimental conditions. It was found that the effects of pure CO2 and CO2-H2S are relatively small, i.e., CO2 increased permeability by 5.5% and CO2-H2S decreased it by 5.5%. Also, CO2-SO2 slightly decreased permeability by 6.25%, while CO2-NO2 showed the most pronounced effect, reducing permeability by 41.6%. The decrease in permeability showed a correlation with decreasing pH of the formation water and this equally correlates with a decrease in geometric mean of the grain diameter. The findings from this study are aimed to be used in future modelling studies on reservoir performance during injection and storage, which also should account for the shifts in boundaries in the CO2 phase diagram, altering the reservoir properties and affecting the cost of storage

Lateral stress evolution in chromium sulfide cermets with varying excess chromium

The shock response of chromium sulfide-chromium, a cermet of potential interest as a matrix material for ballistic applications, has been investigated at two molar ratios. Using a combustion synthesis technique allowed for control of the molar ratio of the material, which was investigated under near-stoichiometric (cermet) and excess chromium (interpenetrating composite) conditions, representing chromium:sulfur molar ratios of 1.15:1 and 4:1, respectively. The compacts were investigated via the plate-impact technique, which allowed the material to be loaded under a onedimensional state of strain. Embedded manganin stress gauges were employed to monitor the temporal evolution of longitudinal and lateral components of stress in both materials. Comparison of these two components has allowed assessment of the variation of material shear strength both with impact pressure/strain-rate and time for the two molar ratio conditions. The two materials exhibited identical material strength despite variations in their excess chromium content

A review of developments in carbon dioxide storage

Carbon capture and storage (CCS) has been identified as an urgent, strategic and essential approach to reduce anthropogenic CO2 emissions, and mitigate the severe consequences of climate change. CO2 storage is the last step in the CCS chain and can be implemented mainly through oceanic and underground geological sequestration, and mineral carbonation. This review paper aims to provide state-of-the-art developments in CO2 storage. The review initially discussed the potential options for CO2 storage by highlighting the present status, current challenges and uncertainties associated with further deployment of established approaches (such as storage in saline aquifers and depleted oil and gas reservoirs) and feasibility demonstration of relatively newer storage concepts (such as hydrate storage and CO2-based enhanced geothermal systems). The second part of the review outlined the critical criteria that are necessary for storage site selection, including geological, geothermal, geohazards, hydrodynamic, basin maturity, and economic, societal and environmental factors. In the third section, the focus was on identification of CO2 behaviour within the reservoir during and after injection, namely injection-induced seismicity, potential leakage pathways, and long-term containment complexities associated with CO2-brine-rock interaction. In addition, a detailed review on storage capacity estimation methods based on different geological media and trapping mechanisms was provided. Finally, an overview of major CO2 storage projects, including their overall outcomes, were outlined. This review indicates that although CO2 storage is a technically proven strategy, the discussed challenges need to be addressed in order to accelerate the deployment of the technology. In addition, beside the necessity of techno-economic aspects, public acceptance of CO2 storage plays a central role in technology deployment, and the current ethical mechanisms need to be further improved

A suggested prototype for assessing bone health

Background- Osteoporosis is becoming a health concern worldwide. Considering the fact that prevention plays an important role in reducing the burden of this silent disease and in view of the limited resources available, many countries have adopted certain programs to fight osteoporosis through shifting their attention towards at-risk individuals. The Iranian Multicenter Osteoporosis Study (IMOS) is one of these programs. The program aims to assess bone health and the prevalence of vitamin D deficiency in different parts of Iran with various altitudes, latitudes and lifestyle habits in a way that the results could be generalized to the country. Method- The present article presents the protocol used in the third phase of the study. It was designed based on the experiences gathered in the previous phases to overcome the shortcomings particularly subject loss. The questionnaire applied in this study was developed based on a thorough literature review of the risk factors and secondary causes of osteoporosis and was approved by an expert panel. It should be added that while the majority of the existing studies aim to study a certain aspect of osteoporosis, the present protocol provides the information needed for policy makers and researchers to study different osteoporosis-related issues. Conclusion- The authors believe the protocol, to be implemented with small modifications, can help policymakers in different parts of the world, particularly developing countries, gather accurate information on different aspects of bone health at the national level. © 2015, Academy of Medical Sciences of I.R. Iran. All rights reserved

Distribution patterns of rocky shore cructacea in the Hormuz Island

A general description of distribution patterns of rocky shore cructacea along the Hormuz Island coasts is presented to provide the context for comparisons of distribution patterns of this intertidal organisms. In order to test if there was any variation in species distribution and abundance from upper to lower intertidal zone (littoral zone) along the entire rocky shores of the Hormuz Island, three main regions (west, south and south-eastern) were studied and 3 transects were sampled in each region. At each one of the 9 transects the shore was levelled and a general qualitative description was made, which also aided grouping of subsequent quantitative sampling. Photographs and slides were taken from the live specimens and then specimens were fixed in 4% formalin and transported to lab for analyses. The upper zone was characterized by the presence of Balanus amphitrite. The midlittoral zone was essentially dominated by Balanus amphitrite. The distribution patterns observed on the lower zone showed a similarity between rocky shores located in south and south-east of the Hormuz Island dominated by Elasmopus sp.. It has also provided important information on abundance and seasonal distribution of cructacea in rocky shores of the Hormuz Island. According to the results abundance of cructacea was markedly lower in Summer compared to Winter. In conclusion species of cructacea is prevailing and environmental conditions and bed is the main reason for high abundance of this class. Distribution of crustacean is mainly affected by prevailing environmental conditions and the substratum type

Research paper: Comparing the diadochokinetic rate in farsi-speaking young and older adults

Objectives: Speech Diadochokinesis (DDK) is defined as the ability to produce repetitive and fast speech movements. This study aimed at comparing the DDK rate between Farsi-speaking young and older adults. Methods: In this study, 244 normal adults (122 males and 122 females) were divided into two groups of young people (20-49 years) and elderly (50-69 years). DDK tasks was performed based on two ways: the participant was asked to produce /pa/,/ta/,/ka/,/pata/,/paka/,/taka/, and /pataka/ sounds in 5 s; and to repeat single syllable sounds (/pa/,/ta/,/ka/) 20 times, two syllables sounds (/pata/,/paka/,/taka/) 15 times, and a three syllables sound (/pataka/) ten times, separately and quickly. The independent T-test, one-way ANOVA, and Pearson correlation were used for data analysis. Results: The results indicated a significant negative and weak correlation between age and all syllables in the specified time (range:-0.139 to-0.254), and a positive and weak correlation between age and time with respect to the repetition of all syllables (range: 0.121 to 0.245). There was no significant difference between genders in both ways (P>0.05). Discussion: The results indicated different DDK rate between the young and elderly subjects that can be used as a benchmark for the diagnosis of disabled individuals in producing repetitive and fast oral movements and also as a basis for clinical assessments. © 2020 University of Social Welfare and Rehabilitation Sciences

Corrigendum: Ethnopharmacological Approaches for Therapy of Jaundice: Part II. Highly Used Plant Species from Acanthaceae, Euphorbiaceae, Asteraceae, Combretaceae, and Fabaceae Families

In the original article, there was a mistake in the legend for Figure 4 as published (the spelling of isosilibin was incorrect). The correct legend appears below. In the original article, there was a mistake in Figure 4 as published (CH3 group was missing in the Silybin structure). The corrected Figure 4 appears below. The authors apologize for these errors and state that this does not change the scientific conclusions of the article in any way