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The dust produced by the electric arc method in the ferrochrome factory contains high amounts of hexavalent chromium, which has a high solubility in water and causes high environmental pollution. The present research has proposed a new method for neutralization of hexavalent chromium present in ferrochrome dust in solution environment by using chemical precipitation method. After checking conventional and non-conventional additives for neutralization by co-precipitation method, Iron sulfate is added to the aforementioned wastewater before release into the environment as a reducing agent of hexavalent chromium to trivalent chromium. Next, calcium sulfate was used as a stable complex forming factor in the system to remove chromium. XRD and XRF analyzes were used to characterize the dust and UV-Visible to determine the amount of chromium removed from the wastewater. The results showed that for 100 g/l of dust dissolved in water, adding 30 g of iron sulfate in the first stage and 20 g of calcium sulfate in the second stage reduces the content of hexavalent chromium from high values to below 10 ppm. Easy, high speed, cheapness and availability of additives are the merits of this method.


 

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Dispersion type of layered clay plated in aqueous media creates different structures and affects the final properties of its suspension. On the other hand, the presence of different electrolytes in some industrial applications affects the stability of clay suspensions. Considering the application of clay nanoparticles in various industries and the importance of this subject, in this research, the effect of preparation method, nanoparticle concentration, type and ionic strength of electrolytic medium and time elapsed on the stability behavior of laponite nanoparticles suspensions were studied. The results showed that preparing of the suspensions indirectly, results in more stable samples. It was observed that with increasing of sodium chloride concentration, the repulsion between the clay plates decreased and the phase separation and instability of the suspensions increased at higher NaCl concentrations. Furthermore, it was seen that in all electrolyte media, gel-like structure develop with increasing of nanoparticle concentration. In presence of bi-valance CaCl2 salt, most of suspensions were unstable and have two phases and increasing of this salt concentration had not significant effect on their stability. In electrolyte media containing mono- and bi- valance salts (studied in this research), concentration of calcium cation determines the type of stability behavior of laponite nanoparticles suspensions.

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Adequate calcium ( Ca ) intake during the crucial growing years maximizes peak bone mass and thus delays the onset of osteoporosis later in life. In addition, Ca plays a protective role against essential hypertension and colorectal cancer. Dairy products, a naturally rich Ca source, are the major source of Ca in our diet. However many people avoid consuming milk, because of economical problems and who are lactose intolerant. For these people, Cafortified nondairy foods can be a significant source of Ca. A number of foods, including bread, staple food, can be fortified with Ca. In this study, formulation and production of fortified Barbari bread with different Ca sources was investigated. In order to, different kind of Barbari breads were prepared with flour fortified with two food-grade inorganic Ca sources such as Ca carbonate and Ca sulfate. Ca was added to flour at two levels: 500 and 1000 mg/ 100 g of flour. one bread was also prepared using ordinary flour. Results of Farinograph and Extensograph tests indicated strength of dough. Results of Farinograph test indicated that the percent of absorbed water, dough development time, dough stability and valorimeter value will increase by adding Ca, while the degree of dough softening in 10 and 20 minates, will reduce. Also atomic absorption spectrophotometry test showed that retaining of Ca in breads was significant ( P< 0.01).CaCO3 and CaSO4 are preffered sources of Ca for the fortification of cereal-based foods as they had no adverse affect on bread quality but CaCO3 is higher in Ca than CaSO4. It is also less expensive. For these reasons, Ca carbonate is a preffered Ca source for fortifying bread.

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Thermolysin is a thermostable protease produced by Bacillus thermoproteolyticus. This enzyme is industrially applicable especially for peptide synthesis. Due to industrial applications, numerous investigations have been performed on thermolysin. In the present study, the role of calcium on thermal, acidic pH, denaturant (urea and SDS) and salt stabilities was studied. In the absence of calcium, t1/2 at 80, 85 and 90 ÛC was 7, 3 and 1 min, respectively. However, in the presence of 10 mM calcium, t1/2 at the same temperatures was >95, 45 and 16 min, respectively. On the other hand, calcium had marginal effect on the pH stability of enzyme. The analyses revealed that SDS and urea contrarily affect on the enzyme stability. The concentration of SDS by which the enzyme activity diminished by half was 0.1 and 0.9 (%W/V) in the presence and absence of calcium, respectively. Oppositely, urea did not reduced and even promoted the enzyme activity in both conditions. Stability of thermolysin in NaCl up to 3M was slightly increased in the presence of calcium while slightly decreased in the absence of calcium. At higher concentrations of NaCl, however, the stability was decreased in both conditions. These results reveal that thermal and SDS stability of thermolysin are strongly Ca-dependent, stability against NaCl and urea are moderately Ca-dependent, and its acidic pH stability is Ca-independent.

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Beauveria spp. as entomopathogenic fungi have extremely diverse insect host ranges.Here, a comparative transcript analysis of a Bassiasin I (BSNI), a Dipeptidyl peptidase (DPP), a Cytochrom P450 monooxygenase (CYP52), a Mitogen activated protein kinase (MAPK), and a Neuronal calcium sensor 1 (NCS) in two isolates of Beauveria bassiana., with low and high virulence, were carried out. For this, induction media, containing isolated cuticles from four insects, and a check medium lacking any cuticular extract were prepared and isolates were allowed to grow on them. Interestingly, up-regulation of BSNI and DPP in induction media was noted in comparison to the check, following normalization with γ-ACTIN. CYP52 was up-regulated in synthetic medium in comparison to cuticular extract. MAPK expression was greater in most virulent isolate once compared with the low virulent isolate. The expression of MAPK was greater in the presence of Caliptamus italicus cuticles and synthetic medium as opposed to others. NCS expression remained on changed in all media tested and can be suggested as a reference gene in transcriptomics of Beauveria spp. genes in future.  

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  In this experiment the effects of preharvest calcium chloride and postharvest hot water treatment as well as the use of polyethylene bags for packaging on the quality improvement of pomegranate fruit during cold storage were studied. For this purpose Calcium chloride was sprayed at two levels on August 2004 (1% and 2%). Pomegranate fruits of Malas - Torsh cv. was harvested at fully ripen stage and treated with hot water (45, 50 and 55C for 20 minutes, 1 minute and 30 second espectively). Thereafter each fruit was warped up in a polyethylene bag and stored in cool store room with 1C and relative humidity of 85% for 3 months. The experiments were conducted using a completely randomized design of three replicates. The results indicated that fruits wrapped with polyethylene had a significant effect on preventing weight loss, improving the appearance as well as marketability of fruits during storage, while showing no effect on pH, TSS and fruit dry matter. Also it was observed that fruits treated in 50'C hot water showed significant improvement of quality while treatment with 45C hot water failed to show such effects. In total, a combination of Calcium chloride and polyethylene bag packaging along with 50C hot water treatment caused improvement in the general quality of stored fruit and decreased fungi infection and chilling index.

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Effects of fortification Setareh flour with iron, folic acid, zinc and calcium on chemical properties (dry gluten, wet gluten, gluten index, protein and zeleny value), rheologocal properties (water absorption, dough strength, dough extensibility, dough loses after 10 and 20 minutes, resistance to extensibility, extensibility index, maximum height of curve and energy), was considered in Barbary breads and compared with control treatment. In this study we have 4 treatments as follows: 1- Setareh pure flour without any fortificant/ as control. 2- Flour which fortified with low dosage of fortificants : (ferrous sulfate 20, folic acid 1.5, zinc oxide 20 and calcium carbonate 900 p.p.m). 3- Flour which fortified with middle dosage of fortificants : (ferrous sulfate 30, folic acid 2, zinc oxide 30 and calcium carbonate 1200 p.p.m). 4- Flour which fortified with high dosage of fortificants : (ferrous sulfate 40, folic acid 2.5, zinc oxide 40 and calcium carbonate 1500 p.p.m). Statistical data have shown that, in all mentioned properties flour treatments fortified with minimum and middle amounts of fortificants had better results than the flour which fortified with maximum amounts of fortificants. Minimum and middle treatments didn’t have any significant differences, so with due attention to international organizations (WHO, FAO) and provide vital micronutrients for body, we propose middle treatment.

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Sugar beet molasses is a well-known, inexpensive and available carbon source for microbial cell growth. Its sugar components are used to produce energy for microbial growth and non-sugar components, especially nitrogen components, have important roles in improvement of cell growth. On the other hand, immobilization of whole cell is establishment and physical limitation of intact cells in specific space that keeps their catalytic activity and provides the possibility of reuse of the cells. This technique allows continuous and accelerated biological processes. It also improves production efficiency and quality and simplifies recycling of product. Immobilized living cells, as controlled catalysts, are able to perform one-step enzymatic reaction and continuous fermentative processes. In this research, E.coli cells were immobilized in calcium alginate hydrogels and using sugar beet molasses as carbon source, were applied for tryptophan production reaction in the presence of its precursors, serine and indole. In comparison between free biocatalysts and immobilized bacterial cells that entrapped in alginate gels, indicated that larger amounts of amino acids (about 42/9%) can produce in calcium alginate. Also the production reaction was followed up for 9 sequential cycles, and results showed that the cells could produce tryptophan amino acid under above conditions. Use of sugar beet molasses (by-product of agriculture industries) for growth of microbial cells and tryptophan production, causes decrease in production cost and more economical production of tryptophan by immobilized E. coli.

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In this investigation levels of calcium were measured on the flag leaves of the suscepti-ble spring wheat cultivar Thatcher and its near-isogenic line that has Yr-18 gene-mediated durable adult-plant resistance (APR ). The results showed that crystals of vari-ous shapes were frequently present on the infected leaf areas in the spring wheat that has the APR to stripe rust. Crystals were characterized with an energy-dispersive X-ray mi-croanalayser in conjunction with scanning electron microscopy (SEM). More calcium was mobilized into infected areas of the resistance line than into the susceptible genotype. The level of calcium in the non-infected areas of both resistant and susceptible hosts and on the infected areas of the susceptible genotype were nearly the same. The results indicated that calcium mobilization in the resistant near isogenic line upon infection with P. stri-iformis correlated with the elicitation of a defense response conditioned by the Yr-18 gene. This is the first report on the mobilization of calcium in a cereal-rust pathosystem as part of a resistance response.

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The effect of 1,25-dihydroxycholecalciferol [1,25-(OH)2 D3 ] supplementation on laying hen diets was evaluated using diets high and low in Ca (3.0% and 1.8% ) and high and low in P( 0.52% and 0.33% ). Since two levels of 1,25- (OH)2 D3 supplementation (0 and 5 µg/kg diet ) were applied, the experiment was a 2 X 2 X 2 factorial arrangement in a com-pletely randomized design using nine individually housed hens per each 8 treatments (72 in total). The hens were fed the diets for 28 days and records were kept on body weight, egg production, feed intake, egg weight, and egg specific gravity. At the end of the ex-periment, the hens were bled for plasma Ca and P determination and after being eutha-nased the left tibia removed for bone ash measurement. The corn-soybean meal based diet contained 0.1% Cr2O3 as an indicator for determining Ca, P and phytate phosphorus re-tention at 14 and 28 days. 1, 25-Dihydroxycholecalciferol supplementation had no effect on hen weight, egg production or feed intake. However, large increases in egg specific gravity were obtained when 1, 25-(OH)2 D3 was fed to hens receiving the low Ca diet. All of the treatments had significant effects on bone ash. The greatest effect of 1, 25-(OH)2 D3 on bone ash was obtained in those hens fed the high Ca and P diet that was then supple-mented with 1,25-(OH)2 D3 (49.3% vs 53.9% bone ash). At day 14, the high Ca diets de-creased phytate P retention while at d 28 the high P diets decreased phytate P retention.

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  The probiotic, Lactobacillus acidophilus PTCC 1643 was encapsulated in calcium alginate beads with the objective of enhancing survival during exposure to the adverse conditions of the gastro-intestinal tract. The probitic was incubated in simulated gastro-intestinal conditions for 0, 30, 60, 90 and 120 min. at 37 ^oC.  The survivability of the probiotic, L. acidophilus PTCC 1643 was expressed as the destructive value (D-value). Particle size distribution was measured using laser diffraction technique. bead appearance was observed by scanning electron microscopy (SEM). The alginate coat prevented acid-induced reduction of the probiotic in simulated gastric juice (pH 1.5, 2 h), resulting in significantly (P < 0.05) higher numbers of survivors due to retarding the permeation of the gastric fluid into the cells. After sequential incubation in simulated gastric (60 min) and intestinal juices (pH 7.25, 2 h), number of surviving cells were 6.5 log cfu ml ^-1 for encapsulated L. acidophilus while 2.3 log cfu ml ^-1 was obtained for free cells.

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Confocal laser scanning microscopy (CLSM) is a revolutionary advance in the field of light microscopy which, in recent years, has been used on interaction studies between host and pathogen. This study carried out on the flag leaves of the susceptible spring wheat cultivar (Triticum aestivum L.) known as Thatcher and its near isogenic line with the Yr-18 adult-plant resistance gene to stripe rust fungus (Puccinia striiformis f. sp. tritici), by confocal laser scanning microscopy. A suspension of fresh urediniospores of stripe rust, isolate SR99-UA (race, 70E 128) in a light mineral oil ( Soltrol, 170 ) was sprayed on the flag leaves in vitro, then four segments were sampled at 2, 4, 8, 12 and 18 days after inocu-lation. These segments were further divided into 1-2 cm. For detailed observation, two fluorescent dyes Acridin orange and X-Rodamin-1, known to be nucleic acid and calcium binding probes, were used, respectively. CLSM made it possible to visualize host/pathogen interaction in serial without sectioning at a three dimensional level from adaxial to aboxial leaves. According to the results, no difference in pre-penetration behav-ior of the fungus in the two genotypes was observed. During the early stages of penetra-tion, host cell necrosis was occasionally seen only on the resistant genotype. Few dead cells were observed on the susceptible host 12-18 days after inoculation. However, by this time, the resistant host had a markedly high number of dead cells; there were numerous ne-crotic areas or pustules resembling hypersensitive response. In the infected areas and around the pustules of the resistant host a remarkable red color was observed by the presence of a thick fluorescence rich calcium layer. The intensity of calcium fluorescence in the non-infected areas of both genotypes and in the infected areas of the susceptible host were nearly the same, indicating calcium mobilization as part of the defensive re-sponse in resistant near isogenic lines containing the gene Yr-18. This result indicated that calcium mobilization at the point of challenge by the pathogen played an important role in the near isogenic resistance line of Thatcher in the wheat stripe rust pathosystem. This is the first report on calcium mobilization in a cereal rust pathosystem as a part of the re-sistance response.

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Aim: Fire is one of the most important ecological disturbances in rangelands which change the characteristics of vegetation and soil. Up to now few studies have been conducted to study the short-term effects of fire on soil and vegetation in semi-arid shrubland. The positive or negative effects of fire on soil and vegetation of rangeland have been investigated in this research.
Materials and Methods: Soil pH, electrical conductivity (EC), total potassium (K), calcium (Ca), sodium (Na), and magnesium (Mg) content were selected as soil attributes and vegetation richness, diversity and density (percent
ground cover) as vegetation properties. Vegetation and soil sampling was performed based on systematic randomized method along 3 transects (The length of transects in the control and burnt area was 100 m and the distance between each plots was 10 m). Information about vegetation traits (production, density, diversity, richness and evenness) were recorded in 1 m² plots. Soil samples were taken at two depths of 0-15 and 15-30 cm by auger.
Findings: Compared to unburnt rangeland, the percentage of vegetation (16.30 %), production (20.47 Kg ha^-1) and density of vegetation (6.74 %) in burnt region have been decreased significantly (P<0.05).
Conclusion: The results of the present study had shown a significant decrease in species diversity and richness in burnt rangeland. There were not any positive effects of fire on soil or vegetation cover in studied area.

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 Aspergillus flavus is one of the important species of molds that can produce toxins during improper storage of wheat grains. In this study, different amounts of calcium oxide (0, 0.5, and 1%) were mixed with wheat samples containing mold spores. After 20 days, the samples were exposed to gamma radiation (0, 5, 10, 15, and 20 KGy). The presence of A. flavus, Aflatoxin B₁ (AFB₁), aflatoxin B₂ (AFB₂), aflatoxin G₁ (AFG₁), and aflatoxin G₂ (AFG₂) was assessed in samples. The results indicated that the effects of calcium oxide, gamma irradiation, and their interactions were significant on A. flavus, AFB₁, and AFB₂ contamination. Furthermore, other toxins like AFG₁ and AFG₂ were not found in the samples. An additional reduction in AFB₁ and AFB₂ was observed when irradiation was accompanied by Cao, and the maximum inhibition of aflatoxin production was achieved at 0.5% CaO. Consequently, based on the standard maximum limit of 10 KGy for cereals, the findings of this research suggest that 0.5% of calcium oxide and 10 KGy of irradiation could be applied in the storage of wheat grains to mitigate A. flavus, AFB₁, and AFB₂.

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Iran is one of the most important fig producer countries around the world. Intermediate moisture fig is a processed product. One problem about intermediate moisture fig is that the color will be changed and transmute to brown during storage after processing. The purpose of this research was to study soaking temperature and time effects and to evaluate the effects of calcium chloride, cysteine, sodium metabisulphite and citric acid in various concentrations on prevention of semi-moisture fig browning at room temperature. Chemical compounds (protein, total sugar, fat, fiber and moisture) of fig samples were determined. In order to prepare product five different periods of time(3, 6, 9, 12, 15 min) and five different degrees of temperature (20, 40, 60, 80, 100°C) based on central composite rotational design were used. Samples were kept in room temperature for 2 weeks to evaluate the effects of soaking parameters on color and texture of product. After that moisture, color and texture of samples were determined. First different solution of calcium chloride (0.6, 1, 1.5, 2% w/w), citric acid (0.5, 1, 2, 3%w/w), cysteine (0.05, 0.07, 0.2, 0.5%w/w) and sodium metabisulphite (500, 800, 1000 and 1200 ppm ) were prepared. Dried figs were dipped in prepared solutions and water was used to evaluate control samples to optimize the time and temperature, then color of the samples were measured in specific period of time during four months. Results showed that temperature of 60°C and 3min interval provided 20% moisture in the product which assessed as the best moisture content for preserving color and texture. The most desirable L value was obtained using citric acid (1, 2, 3%w/w) and Calcium chloride (1.5%w/w). However sodium metabisulphite and cysteine in concentration of 0.07%, 0.05%, 0.2% showed significant difference with control, the results were not satisfactory. Results showed that using suitable temperature in rehydration of fig to inactivate poly phenol oxidase and chemical treatments to postpone and reduce the browning reaction rate were effective.    

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The changes of total calcium content of Persian sturgeon, Acipenser persicus follicles were investigated during different stages of germinal vesicle migration. Total calcium content increased during maturation and ripening of the oocytes i.e. migration of nucleus toward the animal pole. According to data, the total calcium of follicles with Polarization Index (PI: the ratio of the distance of the germinal vesicle from the animal pole over the animal-vegetal oocyte diameter×100) less than 5.2 (group I) were significantly higher than those in groups with 5.7< PI< 8.1 (group II) and PI> 9.4 (group III). Also, there were no significant differences observed in total calcium content of follicles with PI> 9.4 (group III) and follicles retained for 20 days in body cavity with PI> 10.5 (group IV). As well, there was a significant negative relationship observed between PI values and total calcium content of follicles. It is concluded that calcium is accumulated during the final oocyte maturation in Persian sturgeon.

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In this research the effect of both calcium carbonate nanoparticles and PP-g-MA ones on impact strength and Young’s modulus of Polypropylene (PP) are investigated experimentally. Two kinds of CaCO3 nanoparticles (monolayer-coated and uncoated) are used to investigate the effect of surface treatment of nanoparticles on the mechanical properties of these composites. All samples are mixed in a co-rotating twin screw extruder and are formed into standard tensile and impact bars using the injection molding method. The effect of surface modification of nanoparticles and presence of PP-g-MA on the dispersion of calcium carbonate nanoparticles in polypropylene matrix are studied by field emission scanning electron microscopy (FESEM). The results show a good agreement between the TGA analysis and the related theory. The results also show that surface modification of calcium carbonate nanoparticles and also the PP-g-MA are affective in improving the distribution and dispersion of nanoparticles in the PP matrix. Increasing of the calcium carbonate nanoparticles improves both the impact strength and the Young's modulus of polypropylene. The more the PP-g-MA is added to PP matrix the more the impact strength of the samples increases and the less their Young's modulus decreases.