Different Concentrations Of Zinc Research Articles

Long‐term incorporation of Selenium and Zinc in microalgae Isochrysis galbana and Nannochloropsis oculata and its effects on rotifer

Rotifers are widely used in hatcheries to feed small-sized aquatic larvae although one of their disadvantages is the lack of zinc and selenium 5- and 30-fold lower than in copepods, respectively. To improve the rotifers quality, different concentrations of zinc and selenium (2, 4, 5 and 10 mg L−1 of each mineral) were added to the medium of the microalgae Isochrysis aff. galbana and Nannochloropsis oculata for 4 days, and then the microalgae were harvested and concentrated to feed the rotifers. N. oculata accumulated a greater amount of Zn and Se into cells than I. galbana. The cell size of algae given 0, 2, and 4 mg L−1 of minerals did not change in both microalgae, but enrichment of the microalgae with the 5 and 10 mg L−1 decreased the sizes and paled the colour of cells and increased cell division. The 2 mg L−1 was the best group for rotifers in terms of growth (population density, number of eggs, egg ratio, Specific growth rate, the maximum number and doubling time), and contained the second-highest level of Zn (69.26 ± 0.60) and Se (103.5 ± 5.0) content within a safe limit. Thus, rotifers enriched with Se and Zn can be used as a mineral delivery method to cover the nutritional requirements of marine larvae.

Effect of Different Zinc Sources and Concentrations on the Biomass Yield of Saccharomyces cerevisiae Yeast.

Zinc incorporation and the growth of Saccharomyces cerevisiae were investigated in a culture supplemented with three inorganic zinc salts, i.e. zinc sulphate, zinc chloride and zinc nitrate. The cultivation was performed on a yeast extract peptone dextrose (YEPD) broth medium. The growth of yeast was carried out at different concentrations of zinc, i.e. 0, 30, 60, 90 and 120mg 100ml-1. It was found that the addition of different zinc sources at 30mg 100ml-1 concentration produced higher biomass yield ranging 1.00-1.03g from 100ml-1 of cultivation medium, while higher zinc concentration in the medium caused significantly lower yields of yeast biomass. The amount of zinc in yeast cells was determined by an atomic absorption spectrometer (AAS). The highest amount of zinc in yeast cells was achieved when added in the form of zinc sulphate at a concentration of 120mg 100ml-1. The increment of intracellular zinc was up to 9889.67mgkg-1 of biomass.

Response of Three Flax Genotypes (Linum usitatissimum L.) to Foliar Spraying with Different Concentration of Zinc and Boron under the Dryland Conditions of Nineveh Governorate

A field experiment was conducted during the winter season for the years 2018-2019 and 2019-2020 successively to study the effect of foliar application of zinc and boron on growth traits, yield components and quality of three flax genotypes (Lithuania, Ariana and Linot). The experiment included three concentrations of zinc (0,5 and 10 mg zinc/L) and three concentrations of boron (0, 6 and 12 mg boron/L) implemented according to the factorial experiment in a Completely Random Block Design. The main findings could be summarized as follows:- The results indicate that the Lenot genotype gave the highest values ​​for the traits of plant height, stem diameter, number of fruiting branches, number of capsules/plant, number of seeds/capsule, weight of thousand seeds, total seed yield (tons/ha) and oil yield (tons/ha). for seasons 2018-2019 and 2019-2020 respectively.Foliar application with zinc on plant leaves at a concentration of 5 mg zinc/liter led to a significant increase in plant height, number of fruiting branches, number of capsules/plant, number of seeds/capsule, weight of thousand seeds, total seed yield (tons/ha), oil yield (tons/ha) in both growing seasons.Adding boron application on plant leaves at a concentration of 6 mg boron/liter led to a significant increase in plant height, stem diameter, number of fruiting branches, number of capsules/plant, number of seeds/capsule, weight of thousand seeds, total seed yield (tons/ha) and oil yield (tons/ha) for seasons 2018-2019 and 2019-2020, respectively.In general, it can be concluded that the highest total yield of seeds per unit area can be achieved by planting Lenot genotype and adding zinc on plant leaves at a concentration of 5 mg/L and boron at a concentration of 6 mg/L with in Dryland Conditions of this study.

The Influence of Zinc and Heavy Metals in Feed and Water on the Quality of Cryopreserved Bull Semen

Abstract This study aimed to assess the influence of different concentrations of zinc (Zn), lead (Pb), mercury (Hg) and cadmium (Cd) found in the feed and water provided to bulls on the concentrations of these metals in cryopreserved bull semen, and to determine their influence onto semen quality parameters. Correlations between heavy metal concentrations in the semen and the quality parameters of semen as estimated by computer-assisted sperm analysis (CASA) and flow cytometry (FC) methods were determined. A total of 40 cryopreserved semen samples originating from bulls housed in 4 different centers for artificial insemination (A, B, C and D) were examined, making a total of 160 samples. The concentrations of metals and semen quality parameters were determined in cryopreserved semen of 10 bulls from each center, namely 4 samples from each bull. Concentrations of Zn, Pb, Hg and Cd in hay and concentrated feed were within the allowed limits as proposed by the National Research Council (NRC, 2000). A strong negative correlation was detected between curvilinear velocity (VCL) and Zn concentrations in the semen (P < 0.01; r = -0.772) in group D, and a positive correlation of VCL with Pb concentrations (P < 0.05 and r = 0.718) in group B. Mercury concentrations in cryopreserved semen correlated negatively to the percent of live sperm cells with intact acrosomes (V/IA: P < 0.05; r = -0.640) and positively with the percent of dead sperm cells with damaged acrosomes (D/DA: P < 0.01; r = 0.766) in group D. This finding confirms the hypothesis that Hg, even at low concentrations, may cause acrosome damage.

Imaging and detection of cell apoptosis byIn vitrophotodynamic therapy applications of zinc (II) phthalocyanine on human melanoma cancer

This study aims to investigate the photodynamic therapy (PDT) effects on MeWo (human melanoma cells) and HaCaT (normal human keratinocyte cells) by light stimulation of different concentrations of Zinc (II)-tetra-tert-butyl-phthalocyaninato (ZnPc). MTT viability assay data indicated that a 25 μM concentration of ZnPc is cytotoxic to the melanoma cancer cells while this concentration of ZnPc is not cytotoxic for the HaCaT cell line. Moreover, the results showed that photoactivated ZnPc at 12.5 μM concentration reduced the cell viability of the MeWo cell line to about 50 %. At this photosensitizing concentration, the efficacy of light doses of 20, 30, 40, and 50 J/cm2 was evaluated against MeWo and HaCaT cells. ZnPc at a concentration of 12.5 μM activated with a light dose of 50 J/cm2 was the most efficient for the killing of MeWo cells. In conclusion, the 12.5 μM of ZnPc with the treatment light dose of 50 J/cm2 from a RED light source was adequate to destroy MeWo cells by the ROS-induced apoptosis mechanism. It also exhibited low killing effects on healthy HaCaT cells. These findings are supported by the results of apoptosis with the Annexin V & Dead Cell Kit and fluorescence imaging.

Physiological, Biochemical and Energetic Characteristics of Torulaspora globosa, a Potential Producer of Biofuel

It was obtained that the yeast Torulaspora globosa VKPM Y-953 is suitable for the production of biodiesel fuel. Zinc plays an important regulatory role in the metabolism of the studied strain. The study of the growth parameters and the fatty acid profile of the yeast T. globosa showed that the limitation of its growth by ethanol, at different concentrations of zinc in the medium, considerably influences the chemical composition and the energy content of yeast cells, but not their yield by weight (Yx/s). The increased concentrations of zinc in the medium, in combination with the yeast growth limitation by ethanol, elevated the content of lipids in the cells by 28% and diminished the content of proteins by 14%. At the same time, the limitation of yeast growth by zinc decreased Yx/s and energy (ηX/S) by 2.6 and 3.1 times, respectively. In this case, the content of lipids in cells fell by 72%, while that of proteins rose by 65%. The fatty acid profile of the T. globosa cells was used to estimate the main characteristics of biodiesel (iodine value, cetane number, density, and kinematic viscosity). The biomass of T. globosa can also be used in agriculture as a feed additive rich in essential amino acids.

Effect of foliar application of zinc and boron on growth and yield of cauliflower (Brassica oleracea var.bortrytis L.)

The field experiment was carried out during rabi season of 2018-2019 at Research farm, Raja Balwant Singh College, Bichpuri Agra,(U.P) to study the effect of different concentrations of zinc and boron as foliar spray on the vegetative growth and yield of cauliflower (Brassica oleracea var.bortrytis). Nine treatments with three replications were evaluated in randomized block design. The results revealed that the maximum plant height (44.90 cm), diameter of stem (1.68cm), length (38.90 cm) and width (24.55 cm) of longest leaf were recorded with the foliar spray of 0.50% Zn + 0.2% boron solution .The maximum values of spread of plant along the row(53.51cm)and across the row (55.25 cm) and fully opened leaves per plant (12.94) were recorded with the foliar spray of 0.25% Zn +0.2% boron solution. The yield of cauliflower curd was recorded maximum (343.46 q ha-1) with foliar application of Zn (0.50%) + boron (0.2%). The increase in yield with this treatment was 23.9 % higher than obtained with control (277.13 q ha-1).The lower values of growth and yield attributes were recorded under control .In general combined application of zinc and boron was found significantly superior over their alone application

Biological and antibacterial properties of composite coatings on titanium surfaces modified by microarc oxidation and sol-gel processing.

The aim of this study was to assess the biological and antibacterial properties of composite coatings on titanium surfaces modified by microarc oxidation and sol-gel processing. A layer of hydroxyapatite (HA) with different concentrations of zinc (Zn) ions, prepared by the sol-gel method, was coated on microarc oxidized Ti (MAO-Ti) substrates. Five groups of specimens were tested. The microstructures, elemental compositions, and chemical phases of the composite coatings were investigated, and the biological and antibacterial properties of specimens were evaluated in vitro. The EDS and XRD results confirmed the composite coatings contained HA and Zn ions which was formed on titanium surfaces. The proliferation and ALP activity of BMSCs was significantly higher in group MAO-Ti+HA and MAO-Ti+HA+Zn(High), but MAO-Ti+HA+Zn(High) showed better antibacterial performance. The MAO-Ti substrate coated with the higher Zn concentration in the HA coating exhibited not only favorable biocompatibility, but also antibacterial action against Gram-negative anaerobic bacteria.

RESPONSE SOME QUALITY CHARACTERISTICS OF SUNFLOWER (Helianthus annuus L.) VARIETY TO ZINC SPRAYING

A field experiment was carried out in the Spring and Autumn seasons of 2018 in Al-Subaihat village (latitude 33° 21- N and longitude 43° 46- E) Fallujah city - Al-Anbar governorate in silty-loam soil. To study the effect of two factors which were foliar zinc application different concentration of zinc 0, 0.5, 1.0 and 1.5 kg Zn h1 in the form of aqueous zinc sulfate ZnSO4.7H2O (46% Zn) on the Qualitative Characteristics of three varieties of sunflower (Tarsan8018, Esahaqi 1 and Aqmar). The layout of experiment RCBD ,arrangemental in Factorial experimental units distributed (36 experimental units) with three replicates. The results showed significant different between cultivars in most of the studied traits. Aqmar gave the highest oil content of 54.14 and 51.40% for the both spring and autumn respectively. For the autumn season, Tarsan1018 cv. recorded highest mean percentage of unsaturated fatty acids in seeds about 91.73% for spring season, While Isahaqi 1 exceeded the highest mean of 90.91% for autumn season. Isahaki 1 plants recorded the highest average carbohydrate percentage of 14.70 and 14.97% Zinc spraying resulted in a significant increase in the seed oil percentage. The concentration of 1.5 kg Zn h-1 achieved the highest mean ( 51.56% ) in spring season , while concentration of 1.0 kg Zn E-1 achieved the highest mean capacity in the autumn season (48.79%) Concentration 0.5 kg Zn h-1 are highest percentage of unsaturated fatty acids was 91.01%. In the autumn season, while the concentration of 1.0 kg Zn h-1 achieved the highest average percentage of unsaturated acids in seeds was 90.56%, also the concentration of 1.0 kg Zn h-1 gave the highest percentage of oleic acid in oil was 68.48% and 27.92% for the two season respectively.

Photonic Crystal Fiber Sensor for Blood with Different Concentration of Zinc

Zinc is one of the important material in human blood because of its effect in defensive system work for properly and it plays an important role in growth, wound healing Medically zinc concentration effect directly in skin health so it's important to make a sensor for discover zinc and its concentration change in human blood for each of male and female. Optical fibers are used as a sensor for detecting zinc and its concentration by transmitted laser signal through the optical fiber by using different types (single mode fiber SMF, photonic crystal fiber PCF) by studying the results of output laser the detection can be seen for zinc concentration change, the design of small PCF which the same LMA_10 but smaller in its radius of core and cladding even the distance between cores. The smallest PCF size has the best detection for all zinc concentration change in blood all that was done by comsol Multiphysics 5.4 simulation program

Methylation-associated silencing of miR-193b improves the radiotherapy sensitivity of esophageal cancer cells by targeting cyclin D1 in areas with zinc deficiency

BackgroundAlthough radiotherapy is an important treatment mode for esophageal cancer (EC), the outcome remains unsatisfactory due to radioresistance, and the key cause of radiotherapy resistance is a change in the cell cycle. Zinc deficiency (ZD) has a significant influence on the cell cycle, and this effect is a common phenomenon in areas with a high incidence of esophageal cancer. MethodsRadioresistant sub-cell lines were established by exposing esophageal cancer cells to nine rounds of X-ray irradiation at a dose of 2 Gy. The cells were treated with a range of different concentrations of zinc and overexpression of miR-193b. And proliferation, colony formation, cell cycle and apoptosis assays were then conducted. Luciferase reporter assays were performed to confirm direct interactions between miR-193b and ZRT/IRT-like protein 5 (ZIP5) and between miR-193b and Cyclin D1. Analysis of clinical and follow-up data was performed using data obtained from 75 patients from Cixian, a well-known high incidence area of esophageal cancer. All these patients are unable to tolerate surgery due to their advanced age or advanced stage, and serum specimens were obtained before the patients received therapy. ResultsThe cell cycle of radioresistant cells is blocked in G0/G1 phase (from 50% to 68%). The expression level of Cyclin D1 was decreased and miR-193b was increased in radioresistant cells (P < 0.001). ZD decreased the proportion of cells in G0/G1 phase both in EC (from 50% to 32%) and radioresistant (from 68% to 47%) cells. And the radioresistance of these two cells were decreased. ZD increased the expression of Cyclin D1 (P < 0.001) and inhibited the level of miR-193b (P < 0.001). Up-regulation of miR-193b recovered the proportion of cells in G0/G1 phase and the radioresistance, meanwhile, recovered the altered expression levels of Cyclin D1 and miR-193b of these two cells by ZD. ZD enhanced DNMT activity both in EC (32%) and radioresistant (26%). And miR-193b was hypermethylated both in EC and radioresistant cells. MiR-193b suppressed Cyclin D1 expression by targeting the 3′UTR of Cyclin D1 mRNA. The expression level of miR-193b in the serum of patients was correlated with the disease control rate (DCR) and had a good diagnostic value for distinguishing DCR of EC patients (AUC = 0.710, 95%CI: 0.580–0.839, P = 0.003). And the level of miR-193b was correlated with overall survival (OS) (HR = 0.208, 95%CI: 0.094–0.464). ConclusionsThe methylation-mediated silencing of miR-193b in EC cells due to ZD increased the expression of ZIP5, and the overexpression of ZIP5 increased the intracellular zinc levels to maintain zinc homeostasis. Meanwhile, the silencing of miR-193b increased the sensitivity of radiotherapy by promoting the expression of Cyclin D1.

Zinc induced leucocyte anomalies in the fresh water teleost Clarias batrachus

Changes in Differential Leucocyte Count (DLC) were evaluated in the blood of the fish species Clarias batrachus and this was used as an in situ indicator of the species’ exposure to zinc.Due to feeding and living in the aquatic environments, fish are particularly vulnerable and are heavily exposed to pollution because they cannot escape from the detrimental effects of pollutants. In the present study, the effects of zinc on the DLC(small and large lymphocytes, neutrophils, monocytes, eosinphils and basophils) were examined under three different concentrations of zinc (1.00 ppm, 3.00 ppm and 6.00 ppm) during 7, 14, 21 and 28 days exposure period. During examination, the percentage of both lymphocytes were significantly lower as exposure time and concentration increased while in the case of neurtophils and monocytes, counts, were higher. Eosinophils showed slight increase whereas basophils showed fluctuations in their results. The study of this research infers that the essential metal in undesirable condition can affect the fish health. DLC represents a suitable biomarker of environmental health and provides a tool for biomonitoring water quality.

Determination of Antibiotic and Heavy Metal Resistance in Paenibacillus lautus 51ATA

Microbial and chemical contamination is one of the biggest environmental problems since exposure to pathogenic microorganisms, such as food poisoning bacteria and their biological by-products, are often associated with disease and allergic reactions. Paenibacillus lautus is an aerobic or facultative anaerobic opportunistic bacterial pathogen, which is found in a variety of sources. In this study, we isolated and characterized P. lautus from Niğde Province, which is a wastewater disposal area and therefore presents a great source of contamination. The bacterial isolate was grown, colony morphology and Gram-reactions were observed. Bacteria were identified by 16S rDNA sequencing analysis, which was performed using DNA samples isolated from pure cultures and amplified by polymerase chain reaction (PCR). Sequencing results were compared against known bacterial strains using BLAST (Basic Local Alignment Search Tool) across databases. Antibiotic resistance against 20 different antibiotics and heavy metal resistance against different concentrations of zinc, copper, iron, cobalt, chromium and silver containing compounds were tested via disk diffusion method. Inhibition zones were examined and minimum inhibitory concentrations were recorded. Our results indicated that P. lautus was resistant to a certain set of antibiotics, while it was sensitive against others. Similarly, the bacteria were resistant against high concentrations of most metals tested. In summary, this study provided the first data regarding the isolation and characterization of Paenibacillus lautus strain from a local source in Turkey, which will account as preliminary data and guide our future efforts to fight against microbial contaminations.

Long-Term Effects of Zinc Deficiency and Zinc Supplementation on Developmental Seizure-Induced Brain Damage and the Underlying GPR39/ZnT-3 and MBP Expression in the Hippocampus.

We previously illustrated that long-term upregulated expression of ZnT-3 in the hippocampus of rats that underwent neonatal seizures was restored by pretreatment with a ketogenic diet. It was recently demonstrated that upregulated expression of ZnT-3 was associated with increased concentrations of intracellular free zinc ions in an in vitro model of glutamate-induced hippocampal neuronal excitotoxic damage. However, there is still a lack of research on the effects of different concentrations of zinc in the diet on developmental convulsive brain injury. The aim of this study was to investigate the effects of different zinc concentrations in the diet on long-term neurobehavioral and seizure thresholds following lithium chloride-pilocarpine-induced developmental seizures. Sprague-Dawley rats (postnatal day 27, P27) were randomly assigned to one of six dietary groups for 4 weeks: normal zinc control group (Control group, 44 mg/kg Zn), Zn-deficient control group (ZD group, 2.7 mg/kg Zn), Zn supplemented control group (ZS group, 246 mg/kg Zn), pilocarpine-induced seizure plus regular zinc diet group (SE group, 44 mg/kg Zn), seizure plus low-zinc diet group (SE + ZD group, 2.7 mg/kg Zn), and seizure plus high-zinc diet group (SE + ZS group, 246 mg/kg Zn). Novel object recognition and passive avoidance tests were performed on rats at P42 and P56. After routine seizure threshold detection and Timm staining procedures at P57, expression of GPR39, ZnT-3, and MBP were detected in the hippocampus by Western blot analysis. The results revealed that the Zinc-deficient diet for 4 weeks aggravated the long-term adverse effects of developmental seizures, evidenced by weight, cognition, seizure threshold and serum zinc concentrations, which were paralleled by expression changes in hippocampal GPR39 and ZnT-3. In contrast, zinc supplementation for 4 weeks significantly improved damage-related changes described above and rescued the abnormal expression of GPR39, ZnT-3, and MBP in the hippocampus. Similar alterations between the expression pattern of MBP and aberrant sprouting of mossy fibers in the hippocampus may indicate that sprouting is a secondary pathological change caused by developmental brain damage rather than the cause of epileptogenesis. Up-regulation of MBP protein levels in the high zinc diet-treated seizure group as well as the corresponding improvement of cognitive impairment and reduced hippocampal mossy fiber regenerative sprouting, may represent a compensatory mechanism for neuronal membrane damage and repair.

Influence of combined sulfachloropyridazine sodium and zinc on enzyme activities and biogas production during anaerobic digestion of swine manure.

In order to study the influence of different concentrations of zinc and sulfachloropyridazine sodium (SCPS) on anaerobic digestion (AD) during biogas production, we determined the levels of urease, dehydrogenase activity, and volatile fatty acids (VFAs) in batch tests. The experiments were conducted in small AD devices at a temperature of 37 °C using swine manure and wheat straw as raw materials. Four digestion trials were performed using different zinc and SCPS contents: control digestion with no additives (CK), SCPS at 630 mg kg-1 dry weight (S), SCPS at 630 mg kg-1 with zinc at 500 mg kg-1 dry weight (SL), and SCPS at 630 mg kg-1 with zinc at 5,000 mg kg-1 dry weight (SH). The biogas accumulation under S was 1.7 times that with CK, while SL and SH produced 78% and 35% of that under S, respectively. Correlation analysis showed that the accumulated biogas was significantly negatively correlated (p < 0.05) with VFAs, and the urease activity was significantly negatively correlated (p < 0.01) with zinc and significantly positively correlated with VFAs (p < 0.05). The dehydrogenase activity was strongly correlated (p < 0.01) with the biogas accumulated during the AD of swine manure.

Implications in studies of environmental risk assessments: Does culture medium influence the results of toxicity tests of marine bacteria?

Two marine bacterial populations (Roseobacter sp. and Pseudomonas litoralis) were exposed to different concentrations of zinc (300, 625, 1250, 2000, 2500 and 5000 mg L−1) and cadmium (75, 250, 340, 500 and 1000 mg L−1) using two culture media (full nutrient Marine Broth 2216 “MB” and 1:10 (vol/vol) dilution with seawater of Marine Broth 2216 “MBSW”), in order to assess population responses depending on the culture medium and also potential adverse effects associated with these two metals. Different responses were found depending on the culture medium (Bacterial abundance (cells·mL−1), growth rates (μ, hours−1), and production of Extracellular Polysaccharides Substances (EPS) (μg glucose·cells−1). Results showed negative effects in both strains after the exposure to Zn treatments. Both strains showed highest metal sensitivity at low concentrations using both culture media. However, different results were found when exposing the bacterial populations to Cd treatments depending on the culture medium. Highest toxicity was observed using MB at low levels of Cd concentrations, whereas MBSW showed toxicity to bacteria at higher concentrations of Cd. Results not only showed adverse effects on Roseobacter sp. and Pseudomonas litoralis associated with the concentration of Zn and Cd, but also confirm that depending on the culture medium results can differ. This work suggests MBSW as an adequate culture medium to study metal toxicity bioassays in order to predict realistic effects on marine bacterial populations.

Acute Toxicity of Zinc Sulfate Heptahydrate (ZnSO4*7H2O) and Copper (II) Sulfate Pentahydrate (CuSO4*5H2O) on Freshwater Fish, Percocypris pingi

This study was carried out to determine acute toxicity of two heavy metals (zinc and copper) to fingerlings Percocypris pingi by static bioassays. The experimental fish were subjected to a range of concentrations of heavy metals. At different exposure periods (24 h, 48 h, 72 h and 96 h), the mortality rate were separately investigated. The median lethal concentration (LC50) was determined with Probit analysis. The LC50 values of zinc for the Percocypris pingi at 24 h, 48 h, 72 h and 96 h were 3.504 mg/L, 2.933 mg/L, 2.852 mg/L and 2.852 mg/L, respectively. But the LC50 values of copper at 24 h, 48 h, 72 h and 96 h were 1.730 mg/L, 1.389 mg/L, 1.340 mg/L and 1.340 mg/L, respectively. The heavy metals were ranked in order of toxicity: copper >zinc. The safe concentration of zinc and copper were 0.2852 mg/L and 0.1340 mg/L, respectively. Physicochemical parameters variables e.g. dissolve oxygen, total hardness, and ammonia nitrogen of aquaria were monitored under different concentrations of zinc (0, 1.60, 2.40, 3.20, 4.00, 4.80, 5.60) mg/L and copper (0, 0.60, 1.00, 1.40, 1.80, 2.20, 2.60) mg/L.

Preliminary study on the effects of heavy metals on the growth and some antioxidant enzymes in Arthrospira platensis‐M2 strain

SUMMARYIn this study, we have analyzed superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione reductase (GR) activities, biomass accumulation and chlorophyll‐a content in the Arthrospira platensis‐M2 strain grown at different concentrations of zinc (Zn), tin (Sn) and mercury (Hg). We found that there is a close relationship between chlorophyll‐a content and biomass accumulation in A. platensis‐M2 strain as a result of Zn, Sn and Hg exposures. Sn was found to be the most toxic heavy metal among others because of the continious inhibition of both biomass and chlorophyll‐a accumulation at 500 and 1000 μg mL−1 concentrations after the third day of the study, while they represented continuous increases at each Zn and Hg concentration over 7 days. Lower concentrations of Zn and Sn stimulate SOD and GR activities remarkably, probably due to oxidative stress caused by heavy metal toxicity. APX activity was significantly lowered by higher concentrations of the three metals used in this study. Our results suggest that higher heavy metal concentrations inhibited SOD, APX and GR activities but biomass and chlorophyll‐a accumulation endured in a time‐dependent manner, possibly due to some different defence mechanisms, which remain to be investigated.

Dry Biomass of the Amazonian Macrophyte Paspalun Repens for Evaluation as Adsorbent Material of Heavy Metals Zn and Cu

The present work aims at the preliminary evaluation of the Paspalun repens macrophyte dry biomass adsorbent material of zinc (Zn) and copper (Cu) metals from water. The diversity of Species is due to the extensive aquatic environment where it is inserted. The Paspalun repens species comes from the Buiucu lake located in the region of Parintins-Amazonas- Brazil. The macrophyte was dried in a mill and then a digestion through biomass microwaves was done before and after its exposure to the solutions containing different concentrations of zinc and copper (1.00, 1.50, 2.00, 3.00 mg mL-1 of metals) for a period of 48 hours. As a source of the metals, zinc sulfate (ZnSO4 7H2O) for zinc, and copper sulfate (CuSO4 5H2O) for copper were used as the source. As a result, the efficiency of Paspalun repens was observed in the metals removal, the highest removal percentage, of 29.67 and 37.07% in the leaves, whereas in the root it was 25.25 and 32.84% (at the concentration 1.0 and 2.0 mg/mL consequently), was of zinc, therefore the dry biomass of this species can be considered as a low cost alternative material in the removal of these heavy metals, contributing to the improvement of water quality.

Studies on ternary PbZnS films suited for optoelectronic applications

ABSTRACTThis paper reports the deposition and characterisation of spray-deposited ternary PbZnS thin films. PbZnS thin films were prepared with different concentrations of zinc (0, 1, 2, 3 and 4 wt-%). XRD studies reveal the polycrystalline nature of the films. The doped films exhibit face-centred cubic structure with a strong (2 0 0) preferential orientation similar to that of the undoped film. Lead sulphide (PbS) unit cell volume contracts with Zn doping. Transparency increases with Zn doping and optical band gap values of the PbZnS films coated with Zn concentration greater than 1 wt-% exhibit a blue shift which may be attributed to Moss–Burstein effect. Electrical studies reveal that all the films have resistivity in the order of 10−1 ohm-cm. The obtained results infer that Zn doping enhances the optical and electrical properties of pure PbS making the doped films suitable for optoelectronic applications.