Cu (II) removal intensification using Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> nanoparticles under inert gas and magnetic field in a microchannel

In the present study, Cu (II) ions removal from aqueous solution was intensified by exciting magnetic nanoparticles under inert gas, magnetic field and combination of these two mixing methods in a T-type microchannel. The flow patterns and liquid–liquid two-phase mass transfer were studied in three different magnet distances from mixing channel (3, 6 and 10 mm) and also in the presence of different inert gas flow rates (1, 3 and 5 mL/min). Depending on the mixing method and the flow rate of both phases, several distinct flow patterns were observed including slugs, droplet, parallel and dispersed flows. The performances of mixing techniques for mass transfer enhancement based on relative removal efficiency ratio (λ) and mass transfer coefficient ratio (γ) were compared with simple layout (without nanoparticles, magnetic field and inert gas). The results showed that simultaneous using of inert gas and magnetic field can drive the nanoparticles as mixer. Liquid–liquid mass transfer with 27–62% enhancement in E and 235–285% in K _L a compared with plain one was observed.     

Constitutive model for cyclic behaviour of cohesionless sands

This paper presents a constitutive model for describing the stress-strain response of sands under cyclic loading. The model, formulated using the critical state theory within the bounding surface plasticity framework, is an upgraded version of an existing model developed for monotonic behaviour of cohesionless sands. With modification of the hardening law, plastic volumetric strain increment and unloading plastic modulus, the original model was modified to simulate cyclic loading. The proposed model was validated against triaxial cyclic loading tests for Fuji River sand, Toyoura sand and Nigata sand. Comparison between the measured and predicted results suggests that the proposed modified model can capture the main features of cohesionless sands under drained and undrained cyclic loading.     

Platinum-group elements distribution and spinel composition in podiform chromitites and associated rocks from the upper mantle section of the Neoproterozoic Bou Azzer ophiolite, Anti-Atlas, Morocco

The distribution of platinum-group elements (PGEs), together with spinel composition, of podiform chromitites and serpentinized peridotites were examined to elucidate the nature of the upper mantle of the Neoproterozoic Bou Azzer ophiolite, Anti-Atlas, Morocco. The mantle section is dominated by harzburgite with less abundant dunite. Chromitite pods are also found as small lenses not exceeding a few meters in size. Almost all primary silicates have been altered, and chromian spinel is the only primary mineral that survived alteration. Chromian spinel of chromitites is less affected by hydrothermal alteration than that of mantle peridotites. All chromitite samples of the Bou Azzer ophiolite display a steep negative slope of PGE spidergrams, being enriched in Os, Ir and Ru, and extremely depleted in Pt and Pd. Harzburgites and dunites usually have intermediate to low PGE contents showing more or less unfractionated PGE patterns with conspicuous positive anomalies of Ru and Rh. Two types of magnetite veins in serpentinized peridotite, type I (fibrous) and type II (octahedral), have relatively low PGE contents, displaying a generally positive slope from Os to Pd in the former type, and positive slope from Os to Rh then negative from Rh to Pd in the latter type. These magnetite patterns demonstrate their early and late hydrothermal origin, respectively. Chromian spinel composition of chromitites, dunites and harzburgites reflects their highly depleted nature with little variations; the Cr# is, on average, 0.71, 0.68 and 0.71, respectively. The TiO₂ content is extremely low in chromian spinels, <0.10, of all rock types. The strong PGE fractionation of podiform chromitites and the high-Cr, low-Ti character of spinel of all rock types imply that the chromitites of the Bou Azzer ophiolite were formed either from a high-degree partial melting of primitive mantle, or from melting of already depleted mantle peridotites. This kind of melting is most easily accomplished in the supra-subduction zone environment, indicating a genetic link with supra-subduction zone magma, such as high-Mg andesite or arc tholeiite. This is a general feature in the Neoproterozoic upper mantle.     

Application of the Dynamic Cone Penetrometer (DCP) for determination of the engineering parameters of sandy soils

Determination of the in situ engineering properties of foundation materials has always been a challenge for geotechnical engineers and, thus, several methods have been developed so far. Dynamic Cone Penetration (DCP) test is one of the most versatile amongst them. In the present research, a light weight simple DCP device was developed and used for evaluation of the engineering properties of sandy soils in laboratory conditions. The device consisted of an 8-kg hammer that drops over a height of 575 mm, and drives a 60° cone tip with 20 mm base diameter into the ground. To control the validation of the results, laboratory direct shear and plate load tests were used as reference tests. The soil sample was a poorly graded sandy soil (SP) taken from alluvial deposits of the Tehran plain. All DCP tests and PLTs were undertaken on compacted soil in a mould with 700 mm diameter and 700 mm height. Based on the results of the experiments, the relationships between Dynamic Penetration Index (DPI), relative density (D_r), modulus of elasticity (E), shear modulus (G), modulus of subgrade reaction (K_S), and the friction angle of the soil were obtained with a high coefficient of determination (> 90%). The repeatability of the test results was also evaluated by calculating the coefficient of variations (C_v), which was less than 30% for all tests.     

Site selection and cost-benefit analysis for artificial recharge in the Baghmalek plain, Khuzestan Province, southwest Iran

Available hydrogeological data for the Baghmalek aquifer, southwest Iran, suggest that in order to counter progressive depletion of groundwater, but at the same time meet the growing demand on groundwater resources, artificial recharge should be considered. The success of artificial recharge schemes requires the integration of many types of data and information. The prime prerequisite in establishing an artificial recharge scheme using the surface spreading technique is identification of a suitable site. Therefore, an integrated investigation, including a detailed assessment of surface and sub-surface geology, and hydrogeological surveys were undertaken. The potential of harvesting storm waters, considering their quality and suspended loads, has been evaluated. Using this background, three sites (including basins and check dam) for artificial recharge are suggested in the north and northeast of the area, where the thickness of coarse alluvium is greatest. On the basis of the collected data, (1) the rate of recharge that can be achieved at the three sites is approximately 2.2 million m³ per year, (2) the cost–benefit ratio is 1:1.32, and (3) the analysis suggests that the project could recover the investment within 3 years.     

Assessing and Modeling the Impacts of Wetland Land Cover Changes on Water Provision and Habitat Quality Ecosystem Services

Natural Resources Research - Understanding the spatial–temporal dynamics of wetland land cover (LC) changes and their impacts on ecosystem services (ESs) is essential for wetland conservation...     

An analysis of the optical light curve of the X-ray binary 3U 1653+35

The purpose of this paper is to provide an estimate of several parameters of X-ray binary system 3U 1653+35, based a study of the optical light curve of the companion of HZ Her.The introductory section gives a general outline of the problem and deals with the general method of estimation of the parameters. In Section 2, the reflection effect in close binary systems is demonstrated in the end of this section we first introduce a new method of evaluation of reflection effect in close binary systems. Section 3 gives an analysis of the optical curve of the X-ray binary system 3U 1653+35, and general discussion.     

Microwave links: The future for urban rainfall measurement?

Microwave links are ideally suited to the urban environment, since there are many suitable vandal-free locations to which the receiver and transmitter can be attached. A signal sent along a link is received with reduced power as a consequence of scattering and absorption by intervening water droplets. Thus a measurement of the power loss can be transformed into a measure of total path rainfall. This paper discusses the requirements for the estimation process to be accurate. The paper presents results using a single frequency, together with the improved results from a dual-frequency link. Potential future applications of microwave links are presented.     

Spatial changes of Extended De Martonne climatic zones affected by climate change in Iran

In order to better understand the effect associated with global climate change on Iran’s climate condition, it is important to quantify possible shifts in different climatic types in the future. To this end, monthly mean minimum and maximum temperature, and precipitation from 181 synoptic meteorological stations (average 1970–2005) have been collected from the meteorological organization of Iran. In this paper, to study spatial changes of Iran’s climatic zones affected by climate changes, Extended De Martonne’s classification (originally formulated by De Martonne and extended by Khalili (1992)) was used. Climate change scenarios were simulated in two future climates (average conditions during the 2050s and the 2080s) under each of the SRES A1B and A2, for the CSIRO-MK3, HadCM3, and CGCM3 climate models. Coarse outputs of GCMs were downscaled by delta method. We produced all maps for three time periods (one for the current and two for the future) according to Extended De Martonne’s classification. Finally, for each climatic zone, changes between the current and the future were compared. As the main result, simulated changes indicate shifts to warmer and drier zones. For example, in the current, extra arid-cold (A1.1m2) climate is covering the largest area of the country (21.4 %), whereas in both A1B and A2 scenarios in the 2050s and the 2080s, extra arid-moderate (A1.1m3) and extra arid-warm (A1.1m4) will be the climate and will occupy the largest area of the country, about 21 and 38 %, respectively. This analysis suggests that the global climate change will have a profound effect on the future distribution of severe aridity in Iran.     

Fat mobilization in water restricted Awassi ewes supplemented with vitamin C

The current study was designed to assess the effect of water restriction on fat metabolism in Awassi ewes orally supplemented with different levels of vitamin C. Experiment 1 (24 days) included four groups, four animals in each, with one group as control receiving daily water. The three remaining groups were watered once every four days, with the third and fourth groups receiving a daily oral dose of 3 g and 5 g vitamin C, respectively. Experiment 2 (21 days) was similarly designed except that the last group was administered one 10 g vitamin C oral dose at the beginning and at the middle of the experiment. Water restriction induced a reduction in feed intake and consequently weight loss in both experiments. Fat cell diameter, insulin, leptin, T3 and T4 concentrations tended to decrease in water restricted animals with or without vitamin C, while fatty acids and cholesterol increased. The observed changes reflect fat mobilization in water restricted Awassi ewes, which seemed to be correlated with insulin and leptin levels. Furthermore, fat mobilization reflected by high fatty acid and low leptin concentrations seemed to be more enhanced by daily supplementation of vitamin C than by the singular high dosages repeated twice, however further research is needed to confirm this observation.