196,324 research outputs found
Hydrogeology of non-salt Gachsaran Formation in Iran: an example from the Zagros Range-Tang sorkh Valley
No full textThe study area of Tang sorkh Aquifer is located on the northern flank of the Derak anticline, a part of the Zagros Mountain Range, in the central-south of Iran. The study area is limited to undifferentiated non-salt Gachsaran Formation (NSGF), mainly composed of alternative layers of marl and marlstone, and gypsum. This paper is focused on the hydrogeological and hydrochemistry characteristics of the NSGF. A detailed geological cross section, perpendicular to the strike of the GF was prepared by detailed field surveying. The thickness of GF is 1,268 m, with 82 alternative units of marl, marlstone, gypsum, sandstone and limestone. The sub-aquifers are limited to four limestone, five gypsum, and one gypsum-halite units. The waters of these sub-aquifers emerge as springs or seepage into the Tang sorkh River (TR). The average discharge of springs emerging from limestone and gypsum units ranges between 0.3–8.4 and 0.5–0.75 l s−1, respectively. The source for sub-aquifers is mainly recharge from precipitation or river water. Marly layers disconnect the hydraulic connection between the sub-aquifers, directing the general flow parallel to the strikes. The lack of sinkholes and caves in the gypsum units is due to the small thickness of sub-aquifers, and consequently, low amounts of recharge water. The springs are classified into four groups based on their lithology, electrical conductivity, type of water, and trend of ion-concentration. The type of water in most of the springs is calcium-sulfate. The electrical conductivity is the main parameter to differentiate the hydrochemistry of the groups. The hydrochemistry of springs depends on the recharge from the TR, and the lithology of sub-aquifers and their adjacent units
The Oligocene Avaj volcanic – plutonic complex of Central Iran: A record of magma evolution and mineral equilibria
No full textThe Avaj Oligocene volcanic – plutonic complex is part of extensive Cenozoic magmatic activity within the Urumieh-Dokhtar magmatic arc of Iran. We use whole rock geochemistry, mineral compositions and crystal size distributions (CSD) in a suite of co-genetic basalt, basaltic andesite and gabbro to determine their petrogenesis. Ca-rich cores in plagioclase (An79-86) overlap empirically modelled compositions, indicating equilibrium crystallization from melts represented by the whole-rock compositions. Clinopyroxene compositions (Mg# 74–80) are compatible with mildly fractionated mantle-derived magmas in an arc setting. Mineral-melt equilibrium is inferred from high Al contents and close correspondence between the measured DiHd and predicted KdFe–Mg (0.23–0.32) in clinopyroxenes, and Kd(Plg/melt)(An–Ab) values of plagioclase cores (0.11–0.15). Clinopyroxene-melt thermometers indicate crystallization at 1119–1173 °C for volcanic and 1099–1134 °C for plutonic rocks. Plagioclase crystal core saturation temperatures range from 1088–1162 °C (volcanic) and 1121–1163 °C (plutonic); these values overlap calculated mineral-melt equilibrium temperatures. Plagioclase CSDs are nearly straight for both volcanic and plutonic samples, with higher nucleation density and steeper slopes for the plutonic samples. Major element variations suggest the Avaj rocks represent co-genetic magmas related by fractional crystallization of the observed mineral phases. We suggest minor crustal assimilation occurred during ascent from a deeper reservoir to a shallower one; CSD data indicate longer magma residence time for plagioclase in the plutonic samples (∼117 years) compared to the residence time of basaltic samples (∼13 years)
Recycled mantle source for porphyry mineralization: U−Pb and Re−Os geochronology, and S–Pb–Cu isotopic constraints from the Urumieh-Dokhtar magmatic arc, central Iran
No full textThe Urumieh-Dokhtar magmatic arc (UDMA) hosts some of the world-class porphyry copper deposits in Iran.
Here, we present high-resolution geochronological and stable isotope data to gain insights into the timing and
source of the metallogeny of Kahang porphyry Cu deposit. Zircon U-Pb data show crystallization age of ca. 15
Ma age for the host porphyry intrusion and Re-Os geochronology yields 14.5 Ma from the molybdenite associated
with the ores. Sulfur isotope values on the sulphide minerals range from - 1.6 ‰ to + 2.1 ‰, indicating a
magmatic source for sulfur. Lead isotopic compositions of the S-bearing minerals are akin to those of the
intrusive rocks, suggesting that the metal was likely sourced from mantle reservoirs. We propose a model for the
UDMA involving slab break-off during the maturity of arc magmatism from the syn- to post-collisional stages of
orogenesis. The δ65Cu data trace a systematic change from the barren to the fertile magmas. We suggest that
partial melting of the sub-continental lithospheric mantle that has previously been refertilized of Cu through time
as the potential source for the formation of ore-bearing magmas
Comprehensive hydrogeological study of the Nubian aquifer System, Northeast Africa
No full textThe Nubian Aquifer System (NAS) is one of the largest known deep aquifers, with an area of 1.7 Mkm2 and a maximum depth of 4000 m. It is located in North-East Africa and shared between Egypt, Libya, Chad, and Sudan countries. The sediments deposited inside intra-cratonic basins from the Precambrian to the Quaternary. The NAS consists of the Nubian sandstone aquifer (NSA) overlain by the Post Nubian limestone aquifer (PNLA) in northern portion of the basin. This study provides a comprehensive review of the NAS including sedimentary basin evolution, geology, geomorphology, current and past climate, hydrogeology, general flow direction, water balance, hydrochemistry, water resources management and permissible exploitation period. The primary mechanisms behind the formation of the deep NAS involve the weathering of granitic igneous rock around the basin, low compressibility sandstone and displacement of saline water trapped during deposition by precipitation since one million years ago. The general flow direction is from the southern heights northward, reaching to a depth of 3500 m below sea level, eventually discharging into the Qattara Depression and the Mediterranean Sea during the pre-development period and in local low-lying oases. The NAS has discovered through hydrocarbon exploration. The Total Freshwater Storage Volume (TFSV) is estimated to be about 500 trillion m3 before exploitation. In 2006, groundwater extraction was 2.17 billion m3. Overexploitation without a scientific plan resulted in drying springs, decreasing water levels and quality, land subsidence and intrusion of saltwater from the Mediterranean Sea. The groundwater age is between 4,000 and 50,000 years at a depth fewer than 750 m and up to one million years at lower depth. Therefore, the majority of the aquifer's TFSV is nonrenewable. The lack of systematic, reliable, locally and timescale distributed data are the main challenge of hydrological studies, especially in water balance estimation. TDS varies from 70 to 8500 mg/l, with the NSA water quality generally better than the PNLA. Some parts of the aquifer have reported heavy elements, including lead, manganese, cadmium, chromium and iron. As the NAS is predominantly nonrenewable, only a small percentage of the TFSV, termed the Permissible Exploited Storage Volume (PESV), can be safely exploited in the future. However, determining the extent, location, and implementation plan for the PESV raises critical questions. In addressing these urgent inquiries, the comprehensive review presented in this paper should be regarded as an initial and crucial step in developing a reliable physics-based numerical model of the NAS aquifer system. This model will allow to explore sustainable management practices that effectively address potential challenges
Promising future for biodiesel: Superstructure optimization from feed to fuel
No full textA superstructure model for maximizing the profit of biodiesel production is presented in this work. The superstructure encompasses a wide range of feedstocks (e.g., waste cooking oil, tallow, rapeseed oil and algae), conventional reaction and separation equipment (e.g., continuous stirred tank reactor, decanter and vacuum distillation) and intensified operation units such as membrane reactor and reactive distillation column. The superstructure model is implemented in Advanced Interactive Multidimensional Modeling (AIMMS). The results present an optimal design of a biodiesel production process from waste cooking oil and tallow with a heterogeneous acid catalyst, a reactive distillation column and additional purification steps for producing pure glycerol which is 40% higher in price than technical glycerol. The total annual profit of the biodiesel production from waste cooking oil is 828,697 USD and from tallow is 976,450 USD. The results show that the combination of feedstock selection and implementation of advanced processing technologies to improve biodiesel production can be achieved with the superstructure optimization method
Antimicrobial and antioxidant activities of fermented meat patty with Lactobacillus strains
No full textThe effect of fermentation by Lactobacillus fermentum PTCC 1638, Lactobacillus plantarum subsp. plantarum PTCC 1745 and Lactobacillus sakei subsp. sakei PTCC 1712 on antimicrobial activity against Alternaria alternate PTCC 5224, Aspergillus parasiticus PTCC 5018, Staphylococcus aureus ATCC 25923, Escherichia coli O157 H7 ATCC 35150 and Salmonella Typhimurium ATCC 14028 as well as antioxidant properties (carbonyl assay, peroxide and anisidine value) in a beef patty during 24 h of fermentation and further storage at 4°C for 8 days were investigated. Results indicated that L. plantarum subsp. plantarum had the highest radical scavenging activity (54.3±1.7%) before fermentation. During the fermentation process, DPPH and ABTS activities of the meat patty were improved in comparison to the control. The highest antioxidative value was observed for L. plantarum subsp. plantarum. All of three strains had a strong antimicrobial effect against pathogenic bacteria and fungi. Oxidation products were enhanced in fermented and non-fermented samples. However, the increasing trend of the oxidation process was mitigated in all fermented samples. In particular, the lowest protein and lipid oxidation values were observed in the samples treated by L. plantarum subsp. plantarum. Generally speaking, fermentation improves the antioxidative and antimicrobial effect of meat patty and lengthens its storage period
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
An integrated approach for characterization of a fractured-rock carbonate aquifer in the Zagros Region of Iran
No full textKarst aquifers typically exhibit a wide range of dissolution effects that include end-members of matrix, fracturedrock, and conduit-dominated types. This study employs an integrated approach involving geological studies, hydrogeological assessments, hydrochemical and isotopic analysis, and dye tracer tests to investigate the Sarvak limestone aquifer (SLA) in the Zagros Region, southwest Iran. Key characteristics of the SLA include numerous stratification boundaries, thin limestone layers with intercalated siliceous and marl impurities, extensive joint and fracture networks, predominant autogenic recharge, and absence of notable point recharge features (e.g., sinkholes, dolines), and the exchange flow with the Bakhtiari River (B-R) has made it a unique aquifer. Numerous pieces of evidence, such as low spatial and temporal changes in groundwater level, insignificant seasonal variations in the hydrochemical and isotopic composition of water samples, and the supersaturation state of groundwater with calcite and dolomite minerals, suggested a slow flow regime in many parts of the SLA. This regime is characterized by low velocity and long residence time of groundwater. The results reveal that despite the high solubility of carbonate rocks, extensive joint networks can limit significant karst development, leading to fluid flow behavior similar to that of fractured-rock aquifers. Therefore, SLA can be considered a fractured rock and karst aquifer. The identified paths with fast flow in the dam area are unremarkable and cannot provide a large portion of the Pelle Khan Spring discharge
Nutritional composition and antioxidant activity of vobla roach (Rutilus rutilus caspicus) muscle tissue exposed to heavy metals
No full textThe present study was carried out to study the toxic effects of different sublethal concentrations of cadmium chloride and lead salts [CdCl2 and Pb(NO3)2] on lipid, carbohydrate, protein contents and antioxidant enzymes of vobla-roach (Rutilus rutilus caspicus), a common Caspian fish species, in laboratory bioassays. R. rutilus caspicus was exposed to various sublethal concentrations of CdCl2 and Pb(NO3)2, i.e. 0.75, 1.5 and 2.25 mg L-1 for 24, 48, 72 and 96 hr. Then, the fishes
were sacrificed and muscle was collected for the determination of carbohydrates, lipids, proteins, lipid peroxidation (LPO), catalase (CAT) and superoxide dismutase (SOD) activities. The results showed that the maximum decrease in lipid, carbohydrate and protein contents were observed 96 hr after treatment with 2.25 mg L-1 of Pb(NO3)2 (55.76%, 46.25% and 48.81%, respectively). Furthermore, antioxidant enzyme activities increased when fishes were exposed to cadmium
and lead. The maximum increase in the lipid peroxidation and superoxide dismutase was recorded at 96 hr after treatment with 2.25 mg L-1 of Pb(NO3)2 (184.47 % and 110.52 %, respectively). According to the results, catalase activity decreased with increasing concentration of heavy metals and exposure duration. The maximum decrease in catalase activity was observed 96 hr after treatment with 2.25 mg L-1 of Pb(NO3)2 (81.21 %). In general, both heavy metals were
highly toxic in muscle of R. rutilus caspicus, with lead showing higher toxicity then cadmium in terms of nutritional parameters and antioxidant enzyme activity
Titanate nanotubes–incorporated poly(vinyl alcohol) mixed matrix membranes for pervaporation separation of water-isopropanol mixtures
No full text
Mixed matrix membranes (MMMs) base on poly(vinyl alcohol) (PVA) incorporated with titanate nanotubes (TNTs), cross-linked with glutaraldehyde, were prepared. The hydrothermally synthesized TNTs and the membranes were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffractometer (XRD), Thermogravimetric analysis (TGA), Field emission scanning electron microscope (FESEM), and tensile strength analyses. The prepared nanocomposite membranes were used for dehydration of isopropanol by pervaporation process. The effects of the weight fraction of TNTs, feed temperature, and concentration on the performance of the membranes were investigated. The results indicated that incorporation of hydrophilic TNTs could effectively improve the separation performance of PVA membranes in terms of both permeability and separation factor. Based on the results, the separation factor of all nanocomposite membranes was increased. Moreover, the membrane containing 4 wt% of TNTs exhibited the highest separation factor value of 5520, while the maximum value of flux was about 0.126 kg/m
2
h for the membrane containing 10 wt% TNTs. So, there was about 794% and 741% enhancement in separation factor and flux respectively, compared to the pristine PVA membranes. Consequently, the results confirm incorporating TNTs in the PVA matrix could improve the separation of water from isopropanol aqueous solutions effectively due to the intrinsic hydrophilicity and special structure of TNTs.
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