Cu In Combination Research Articles

Effects of elevated temperature and copper exposure on the physiological state of the coral Galaxea fascicularis

The co-occurrence of elevated seawater temperature and local stressors (heavy metal contamination) affects the ecophysiology of phototrophic species, and represents a risk to the environmental quality of coral reefs. Therefore, we investigated the effects of both Cu alone and Cu in combination with elevated temperature (ET) on the physiology of the coral Galaxea fascicularis, and measured the parameters related to the photo-physiology and oxidative state. G.fascicularis is one of the dominant coral species in the South China Sea which exhibits strong adaptability to environmental stress. We exposed the common coral species G.fascicularis to a series of environmentally relevant concentrations of Cu at 29 °C (normal temperature, NT) and 32 °C (elevated temperature, ET) for 96 h. Single polyps were used in the experiments, which reduced individual variability when compared to the coral colonies. The results suggested that: i) Cu or ET had significant negative effects on the actual operating ability of photosystem Ⅱ (PSII), but not on the maximal chlorophyll fluorescence in darkness (Fv/Fm). ii) Symbiodiniaceae density was significantly reduced by high Cu concentrations, for Cu-NT and Cu-ET, a high concentration of Cu (40 μg/L) significantly impacted Symbiodiniaceae density, causing a 75.4% and 81.0% decrease, respectively. iii) the content of malondialdehyde (MDA) in coral tissues increased significantly under Cu-ET. iv) a certain range of copper concentration (25–30 μg/L) increased the pigment content of the Symbiodiniacea. Our results indicated that the combined stressors of Cu and ET made the coral tissue sloughed, caused the coral tissue damaged by lipid oxidation, reduced the photosynthetic capacity of the Symbiodiniacea, and led to the excretion of Symbiodiniacea.

Effects of Rare Earth Metal Promotion over Zeolite-Supported Fe-Cu-Based Catalysts on the Light Olefin Production Performance in Fischer-Tropsch Synthesis.

Fischer-Tropsch synthesis (FTS), a significant reaction for effective H2 utilization, is a promising approach for direct production of light olefins from syngas (H2 + CO). For the FT-Olefin process, an efficient catalyst restricting the product distribution of FTS to light olefins is required. Aligned with this goal, we synthesized 24 catalysts comprising Fe and Cu in combination with rare earth metals (La, Ce, Nd, Ho, Er) and zeolite supports (ultrastable Y and mordenite). FT-Olefin performances of these catalysts were screened using a high-throughput test system at atmospheric pressure, and then promising catalysts were tested under high pressure in a conventional test system. Results show that Nd increases selectivity to light olefins and Ho suppresses C5+ and coke formation. It is also demonstrated that zeolite-metal interaction, leading to a mixture of both acidic and basic sites, is significant in increasing light olefin production. The mordenite-supported 20 wt % Fe, 0.5 wt % Cu, and 0.5 wt % Ho catalyst provides the highest light olefin yield with the lowest coke and heavier hydrocarbon selectivity.

The Dietary Supplementation of Copper and Zinc Nanoparticles Improves Health Condition of Young Dairy Calves by Reducing the Incidence of Diarrhoea and Boosting Immune Function and Antioxidant Activity.

This study was conducted to evaluate the effect of nano copper (nano Cu) and nano zinc (nano Zn) supplementation on the biomarkers of immunity and antioxidant and health status attributes in young dairy calves. Twenty-four young cattle calves were randomly assigned into four groups (6 calves per group) on a body weight and age basis for a period of 120days. The feeding regimen was the same in all the groups except that these were supplemented with 0.0mg nano Cu and nano Zn (control), 10mg nano Cu (nanoCu10), 32mg nano Zn (nanoZn32), and a combination of nano Cu and nano Zn (nanoCu10 + nanoZn32) per kg dry matter (DM) basis in four respective groups. Supplementation of nano Cu along with nano Zn improves immune response which was evidenced from higher immunoglobulin G (IgG), immunoglobulin M (IgM), immunoglobulin A (IgA), total immunoglobulin (TIg), and Zn sulphate turbidity (ZST) units and lower plasma concentrations of tumour necrosis factor-α (TNF-α) and cortisol in the nanoCu10 + nanoZn32 group. There was no effect of treatment on the plasma concentrations of immunoglobulin E (IgE) and interferon-gamma (IFN-γ). Antioxidant status was also better in the nanoCu10 + nanoZn32 group as evidenced by lower concentrations of malondialdehyde (MDA) and higher activity of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), ceruloplasmin (Cp), and total antioxidant status (TAS). However, treatment did not exert any effect on catalase (CAT) activity. Although the nano Cu or nano Zn supplementation, either alone or in combination, did not exert any effect on growth performance or body condition score (BCS), the frequency of diarrhoea and incidence of diarrhoea were lower, while faecal consistency score (FCS) and attitude score were better in the nanoCu10 + nanoZn32 groups. In the control group, one calf was found affected with joint illness and two calves were found affected with navel illness. During the experimental period, none of the calves in all four groups were found to be affected by pneumonia. The findings of this study revealed that dietary supplementation of nano Cu in combination with nano Zn improved the health status of young dairy calves by improving immunity and antioxidant status.

ALDH1A1 Gene Expression and Cellular Copper Levels between Low and Highly Metastatic Osteosarcoma Provide a Case for Novel Repurposing with Disulfiram and Copper.

Aldehyde dehydrogenase 1A1 (ALDH) is a cancer stem cell marker highly expressed in metastatic cells. Disulfiram (Dis) is an FDA-approved antialcoholism drug that inhibits ALDH and has been studied as a candidate for drug repurposing in multiple neoplasia. Dis cytotoxicity in cancer cells has been shown to be copper-dependent, in part due to Dis's ability to function as a bivalent metal ion chelator of copper (Cu). The objectives of this research were to test ALDH expression levels and Cu concentrations in sarcoma patient tumors and human osteosarcoma (OS) cell lines with differing metastatic phenotypes. We also sought to evaluate Dis + Cu combination therapy in human OS cells. Intracellular Cu was inversely proportional to the metastatic phenotype in human OS cell lines (SaOS2 > LM2 > LM7). Nonmetastatic human sarcoma tumors demonstrated increased Cu concentrations compared with metastatic tumors. qPCR demonstrated that ALDH expression was significantly increased in highly metastatic LM2 and LM7 human OS cell lines compared with low metastatic SaOS2. Tumor cells from sarcoma patients with metastatic disease displayed significantly increased ALDH expression compared with tumor cells from patients without metastatic disease. Serum Cu concentration in canine OS versus normal canine patients demonstrated similar trends. Dis demonstrated selective cytotoxicity compared with human multipotential stromal cells (MSCs): Dis-treated OS cells demonstrated increased apoptosis, whereas MSCs did not. CuCl2 combined with Dis and low-dose doxorubicin resulted in a superior cytotoxic effect in both SaOS2 and LM7 cell lines. In summary, ALDH gene expression and Cu levels are altered between low and highly metastatic human OS cells, canine samples, and patient tumors. Our findings support the feasibility of a repurposed drug strategy for Dis and Cu in combination with low-dose anthracycline to specifically target metastatic OS cells.

Recent progress in CO2 reduction using bimetallic electrodes containing copper

Rising levels of carbon dioxide in the atmosphere have precipitated considerable research efforts aimed at generating energy from renewable sources, such that consuming this energy does not lead to further increases in atmospheric CO2. Simultaneously, atmospheric CO2 represents a useful feedstock for the storage of renewably-generated energy, in particular through electroreduction of CO2 powered by renewables to give hydrocarbon fuels that when burned do not increase net CO2 levels in the atmosphere. In order to bring such renewable-powered production of hydrocarbons from CO2 to reality, improved electrocatalysts for carbon dioxide reduction are required. For example, Cu is the only single metal that demonstrates appreciable Faradaic efficiency for CO2 reduction products that are reduced by more than two-electrons, but pure Cu is not an especially active or selective catalyst for this process. Hence there has been considerable interest in making bimetallic catalysts using Cu in combination with other metals in order to find systems that can reduce CO2 to products such as methane, methanol, ethanol and beyond. In this minireview, we give an overview of recent progress in CO2 electroreduction using bimetallic cathodes composed of copper and various other metals in combination, with a particular focus on studies going beyond two-electron reduction products from the last two years.

Counteracting the Negative Effects of Copper Limitations Through the Biostimulatory Action of a Tropical Plant Extract in Grapevine Under Pedo-Climatic Constraints

In southern Mediterranean areas, vineyards are facing the combination of increasing air temperature, drought and frequency of extreme events (e.g., heat waves) due to climate change. Since most of the berry growth and ripening phases occur during the aridity period, such environmental constraints are responsible for limitations in yield and berry quality. Within this scenario, to achieve vineyard sustainability, renewed approaches in vineyard management have been proposed and the use of plant biostimulants seems a prominent and environmental friendly practice. The aim of this study was to test four combinations of a tropical plant extract and conventional chemicals for disease control on morpho-anatomical, physiological, biochemical and berry quality inVitis viniferaL. subsp.vinifera“Aglianico.” In particular, we aimed to evaluate the possibility to counteract the negative effects of the reductions in copper distribution, by applying the tropical plant extract enriched with: micronutrients, enzymes involved in the activation of natural defense, aminoacids, and vitamins. The halved dose of Cu in combination with the tropical plant extract allowed maintaining a reduced vegetative vigor. In the second year of treatment, the addition of the plant extract significantly improved leaf gas exchanges and photochemistry as well as the synthesis of photosynthetic pigments. At berry level, the plant extract induced an increase in phenolics accompanied by a decrease in soluble sugars. The overall results showed that the expected differences in growth performance and productivity in vines are linked to different eco-physiological and structural properties induced by the various treatments. The tropical plant extract also primed plant defenses at the leaf and fruit levels, mainly due to modifications of some structural and biochemical traits, respectively.

Combined effects of nanoplastics and copper on the freshwater alga Raphidocelis subcapitata

Nanoplastics are recognized as able to interact with other pollutants including heavy metals, and with natural organic matter, with implications for the potential risks to biota. We investigated the interaction of carboxylated polystyrene nanoparticles (PS–COOH NPs) with copper (Cu) and algal exudates (EPS) and how such interaction could affect Cu toxicity towards the freshwater microalga Raphidocelis subcapitata. PS–COOH NPs behavior in the presence of Cu and EPS was determined by dynamic light scattering (DLS), while PS–COOH NPs surface interaction with Cu ions and EPS was investigated by fluorimetric analysis. ICP-MS was used to test Cu ion adsorption to PS–COOH NPs in the presence and absence of algae. The interaction between PS–COOH NPs and the algal cell wall was assessed by fluorescence microscopy. Short- and long-term toxicity tests were carried out in parallel to assess the impact of PS–COOH NPs on algal growth. Results showed altered nanoparticle surface charge and hydrodynamic diameter following algal EPS exposure, supporting the hypothesis of a protein corona formation. In contrast, no absorption of Cu ions was observed on PS–COOH NPs, either in the presence or absence of algae. No differences on algal growth inhibition were observed between exposure to Cu only, and to Cu in combination with PS–COOH NPs, in short-term as well as long-term tests. However, after 72 h of exposure, the adsorption of PS-COOH NPs to algal cell walls appeared to correspond to morphological alterations, revealing potential disturbances in the mitotic cycle. Our findings confirm the ability of PS–COOH NPs to interact with EPS as shown for other nanomaterials. Environmentally realistic exposure scenarios are thus needed for evaluating nanoplastic toxicity, as nanoparticles will not maintain their pristine nature once released into natural media. Prolonged exposure and use of different end-points such as cell morphological changes and EPS production seem more reliable for the investigation of nanoplastic/algal cell interactions which can drive food chain transfer of nanoplastics and ultimately toxicity.

Oxidative and haemostatic effects of copper, manganese and mercury, alone and in combination at physiologically relevant levels: An ex vivo study.

Water contamination with metals due to anthropogenic activity is increasing and subsequent exposure increases the risk of associated toxicity. Exposure is not limited to a single metal but usually involves mixtures of different metals at different concentrations. Little is known about the contribution of this type of exposure, in humans, to the development of non-communicable diseases such as cardiovascular disease, and an increased risk to thrombosis. The World Health Organization has established limits for metal levels in drinking water and this includes levels for copper (Cu), manganese (Mn) and mercury (Hg). In this study, at 100X these limits, the ability of the metals' oxidative effects as catalysts of the Fenton reaction and/or ability to bind glutathione (GSH) were determined. The haemostatic effects of these metals, alone and in combination, at the World Health Organization limit were then evaluated. The ultrastructural and viscoelastic alterations of exposed ex vivo whole blood were also evaluated using scanning electron microscopy and thromboelastography® (TEG), respectively. Cu, alone and in combination with Mn and/or Hg, induced hydroxyl radical formation and reduced GSH levels. Ex vivo exposure caused deformation of erythrocytes and accelerated platelet activation especially for Cu, alone and in combination, with Mn. Reduction in the lysis potential of the clot was also observed for all combinations, especially Cu in combination with Hg as well as Mn alone. Although the TEG findings were not statistically significant, the trends indicate that the exposure to these metals, alone and in combination, adversely affects thrombus formation in ex vivo blood, thereby potentially increasing the risk in exposed individuals for thrombosis.

Response of NAC transcription factor genes against chromium stress in sunflower (Helianthus annuus L.)

Abiotic stresses, such as heavy metals, adversely affect the living groups including plants. It should be ensured that plants are resistant to environmental stresses in order to increase their growth and development. In this sense, it is an important step for agriculture identify stress-related genes whose tolerance against environmental stresses can be increased. NAC transcription factor (TF) genes provide plant growth and development as well as regulate abiotic stress responses. Therefore, this study was conducted to determine expression levels of NAC TF genes (TF ID: Han682, Han2027 and Han2724) against chromium (Cr; 1 mM) stress in sunflower tolerant to heavy metals. The effects of copper (Cu; 0,25 mM), which are micronutrient elements, and exogenous ascorbic acid (AsA; 200 mg/L) treatments on the expression of these genes and some stress parameters such as chlorophyll amount, leaf relative water content, cell membrane damage are examined. According to the results obtained, Cr stress decreased chlorophyll content and leaf water content and increased cell membrane damage. Treatment of AsA and Cu in combination with Cr reduced toxicity by decreasing cell membrane damage by increasing chlorophyll content and leaf relative water content. The results obtained show that Cu and AsA can equally improve Cr stress. Expression profiles of NAC TF genes obtained by quantitative real-time PCR (q-PCR) were changed with plant tissues. NAC TF genes, which are upregulated with Cr stress in the root, have been determined to be a heavy metal response gene.

Copper supplementation in drinking water reverses dietary iron overload‐induced anemia and cardiac hypertrophy in mice

Our previous studies showed that high‐iron (0.88% carbonyl iron) diet feeding of mice and rats lead to impaired growth, severe anemia, tissue copper depletion and cardiac hypertrophy.1,2 Interestingly, these pathophysiological perturbations were prevented by addition of extra copper to the high Fe diet, indicating the role of copper deficiency in the pathogenesis. The current study was undertaken to test the hypothesis that dietary copper supplementation to Fe overload mice could restore systemic copper status, and reverse the anemia and cardiac hypertrophy. Weanling, male C57BL/6 mice were fed AIN‐93G‐based diets containing adequate (~8 ppm) Cu in combination with adequate (~80 ppm) or high (~8000 ppm) Fe for 4 weeks. Then, the mice were given 20 mg/L Cu (as Cu sulfate) in drinking water for another 3 weeks. Subsequently, the iron and copper‐related phenotype of the mice was assessed. High‐Fe diet fed mice showed a significant growth impairment and systemic Cu deficiency, accompanied by severe anemia, decreased serum ceruloplamine (Cp) activity and cardiac hypertrophy. Cu replenishment via drinking water corrected the deficits in hemoglobin (Hb), hematocrit (HCT) and serum Cp levels, restored tissue Cu status, and reversed cardiac hypertrophy. It was further found that high‐Fe feeding significantly impaired intestinal Cu absorption, and disturbed Cu tissue distribution. This study demonstrates that high Fe consumption blocks intestinal Cu absorption, leading to a systemic Cu deficiency which resulted in a severe anemia and cardiac hypertrophy in mice. Cu supplementation corrects these physiologic perturbations. These observations provided further evidence of physiologically‐relevant iron‐copper interactions in mammals.Support or Funding InformationSupported by NIH grant 1R01 DK074867 (to J.F.C.).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Advancement of puberty and enhancement of seminal characteristics by supplementation of trace minerals to bucks

Attainment of puberty in animals is dependent on their age, body weight, nutritional status, genetic and environmental conditions. Nutritionally, organic minerals are suggested to improve semen production, sperm motility and male fertility. In this context, role of organic zinc (Zn) and copper (Cu) in advancing male puberty and semen characters in Osmanabadi goats were studied. Forty one (n = 41) bucks (Aged 5 months) were divided into ten groups and the dietary treatments comprised of a control group (basal diet; without additional trace mineral supplementation) and nine treatment groups that received, in addition to the basal diet, various doses of trace minerals (mg) on per kg dry matter basis, organic Zn as low Zn20, medium Zn40 and high Zn60, organic Cu as low Cu12.5, medium Cu25, high Cu37.5 and combination of organic Zn + Cu as low Zn20 + Cu12.5, medium Zn40 + Cu25, high Zn60 + Cu37.5, respectively fed for a period of 8 months. Bucks fed organic trace minerals reached puberty 28–35 days earlier than control group. In addition, improvement (P < .01) in testosterone hormone (ng/ml) levels (control: 1.63 ± 0.07 VS Zn60: 2.54 ± 0.02; Cu12.5: 6.17 ± 0.05; Cu25: 3.01 ± 0.04; Cu37.5: 2.39 ± 0.06; Zn20 + Cu12.5: 1.94 ± 0.02; Zn60 + Cu37.5: 2.44 ± 0.16 at 240 days), semen production capacity (sperm concentration, volume, mass motility) and semen quality (higher progressive motility, velocity, sperm membrane integrity and acrosome integrity) were observed in supplemented groups (P < .05) than the control bucks. The present study demonstrated that, additional feeding of organic Zn and Cu to growing male goats advanced onset of puberty and improved quantitative and qualitative semen characteristics. The results also implied that the organic Cu had a significant effect on overall performances of bucks as compared to Zn alone or Zn and Cu in combination.

Evaluating the Effectiveness of Essential Oils and Combination of Copper and Lactic Acid on the Growth of E. coli O157:H7 in Laboratory Medium.

In this study, we compared the effectiveness of armoise and clove bud essential oils (EOs) and the combination of low concentrations of copper (Cu) and lactic acid (LA) against E. coli O157:H7 in a laboratory medium. Three strains of Escherichia coli O157:H7 (ATCC700599, ATCC51659, and ATCC43895) were used in this study. Antibacterial activity was determined by measuring the turbidity of a broth medium and by determination of bacterial populations. Our results showed that armoise (0.15% v/v), clove bud (0.1% v/v) EOs, or Cu (50 ppm) in combination with LA (0.2% v/v) caused a minimum 5.0 log reduction of E. coli O157:H7 in the laboratory medium. Cu in combination with LA may thus be preferable to EOs in food in order to control the growth of foodborne pathogens. In addition, the combination treatment of Cu and LA could provide the food industry with a practical approach to reducing the risk of foodborne pathogens.

Responses of the sea anemone, Exaiptasia pallida, to ocean acidification conditions and copper exposure

Ocean acidification (OA) is a growing concern due to its deleterious effects on aquatic organisms. Additionally, the combined effects of OA and other local stressors like metal pollution are largely unknown. In this study, we examined physiological effects in the sea anemone, Exaiptasia pallida after exposure to the global stressor carbon dioxide (CO2), as well as the local stressor copper (Cu) over 7 days. Cu accumulated in the tissues of E. pallida in a concentration-dependent manner. At some time points, sea anemones exposed to 1000ppm CO2 had higher tissue Cu concentrations than those exposed to 400ppm CO2 at the same Cu exposure concentrations. In general, the activities of all anti-oxidant enzymes measured (catalase, CAT; glutathione peroxidase, GPx, glutathione reductase, GR) increased with exposure to increasing Cu concentrations. Significant differences in GR, CAT and to some degree GPx activity, were observed due to increasing CO2 exposure in control treatments. Sea anemones exposed to Cu in combination with higher CO2 generally had higher anti-oxidant enzyme activities than those exposed to the same concentration of Cu and lower CO2. Activity of the enzyme, carbonic anhydrase (CA), involved in acid-base balance, was significantly decreased with increasing Cu exposure. At the two lowest Cu concentrations, the extent of CA inhibition was lessened with increasing CO2 concentration. These results provide insight into toxic mechanisms of both Cu and CO2 exposure to the sensitive cnidarian E. pallida and have implications for environmental exposure of multiple contaminants.

In vitro effects of selenium on copper-induced changes in lipid metabolism of grass carp (Ctenopharyngodon idellus) hepatocytes.

The present study was performed to evaluate the in vitro effects of selenium (Se) supplementation to prevent copper (Cu)-induced changes in lipid metabolism of hepatocytes from grass carp (Ctenopharyngodon idellus). Four groups (control and 100 μM Cu in combination with 0, 5, and 10 μM Se, respectively) were chosen. Compared with the control, activities of glucose 6-phosphatedehydrogenase, 6-phosphogluconate dehydrogenase, malic enzyme, and carnitine palmitoyltransferase I (CPT I) of all three Cu-exposed groups at 24 and 48 h were significantly greater. However, among three Cu-exposed groups, increasing Se concentration tended to increase activities of G6PD and ME at 24 h and 6PGD activity at 24 and 48 h but decreased CPT I activity at 24 h. Compared with the control, Cu exposure alone, or in combination with Se, downregulated mRNA levels of sterol regulatory element-binding protein-1 (SREBP-1c), fatty acid synthase (FAS), acetyl-CoA carboxylase, peroxisome proliferator activated receptor alpha (PPARα), CPT I, and hormone-sensitive lipase (HSL) at 24 h as well as SREBP-1c, FAS, and ACC mRNA levels at 48 h. However, upregulated mRNA levels of PPARα, CPT I, and HSL, as well as decreased triglyceride content, were recorded at 48 h. Thus, although toxic at greater levels, lower levels of Se provided significant protection against Cu-induced changes in lipid metabolism. For the first time, our study indicates the dose- and time-dependent effects of Se addition on changes in lipid metabolism induced by Cu in fish hepatocytes and provides new insights into Se-Cu interaction at both enzymatic and molecular levels.

Investigation of Cu-Based Infiltration Coatings for Metal-Supported SOFC

Metal-supported solid oxide fuel cells are candidates for the next generation of SOFCs. However, the cell design with an FeCr/YSZ-based anode backbone suffers from corrosion when the cells are run at high fuel utilization, which limits the long term durability. In this work, new infiltration coatings based on Cu in combination with Ni:Ce0.8Gd0.2O1.9 (Ni:CGO) have been studied. The candidates for a corrosion resistant coating should limit the formation of Cr2O3 on the surface of FeCr particles. Promising fuel cell performance with an ASR of 0.5 Ωcm2 was obtained at 650 ºC with H2 as fuel. However, various analysis techniques showed no improved corrosion resistance with the addition of a Cu coating.

Modeling of Cu-linked rectification devices by varying torsion angles

Using the nonequilibrium Green's function (NEGF) method in combination with the density functional theory (DFT), we have analyzed the rectifying performance in Cu-linked molecular devices by varying torsion angles (?=0?---90?). The linking effect of Cu atom has been investigated by calculating current-voltage (I-V) characteristics, rectification performance, transmission functions, projected density of states (PDOS), and molecular projected self-consistent Hamiltonian (MPSH). Present calculations revealed that linking of Cu in combination with conjugated dithiocarboxylate (-CS2) and standard thiol linkers significantly affects the metal-molecule coupling asymmetry, and thus the rectifying behavior in molecular devices. Further, the subsequent studies show that the left-right combination of -CS2 linker and Cu atom displays higher rectification ratio at various torsion angles in gold---biphenyl---gold junctions than thiol and Cu linkers. The calculated results are helpful not only in predicting an optimal combination of linking groups for realistic applications but also provide the way for better control of rectification effects in molecular devices.

24-Epibrassinolide regulates photosynthesis, antioxidant enzyme activities and proline content of Cucumis sativus under salt and/or copper stress

Brassinosteroids have been extensively used to overcome various abiotic stresses. But its role in combined stress of salt and excess copper remains unexplored. Seeds of two cultivars (Rocket and Jumbo) of Cucumis sativus were grown in sand amended with copper (100 mg kg(-1)), and developed seedlings were exposed to salt stress in the form of NaCl (150 mM) at the 30-day stage of growth for 3 days. These seedlings were subsequently sprayed with 0 or 0.01 μM of 24-epibrassinolide (EBL) at the 35-day stage. The plants exposed to NaCl and Cu in combination exhibited a significant decline in fresh and dry mass of plant, chlorophyll content, activities of carbonic anhydrase, net photosynthetic rate and maximum quantum yield of the PSII primary photochemistry followed by NaCl and Cu stress alone, more severely in Jumbo than in Rocket. However, the follow-up treatment with EBL to the stressed and nonstressed plant improved growth, chlorophyll content, carbonic anhydrase activity and photosynthetic efficiency, and further enhanced the activity of various antioxidant enzymes viz. catalase, peroxidase and superoxide dismutase and content of proline at the 40-day stage of growth, and the response of the hormone was more effective in Rocket than in Jumbo. The elevated level of antioxidant enzymes as well as proline could have conferred tolerance to the NaCl- and/or Cu-stressed plants resulting in improved growth, water relations and photosynthetic attributes. Furthermore, antioxidant enzyme activity and proline content were more enhanced in Rocket than in Jumbo cultivar.

Influence of Al on resistance and power durability of Cu-based SAW metallizations

In this paper we show an improvement of the power durablity of surface acoustic wave finger electrodes using a metallization layerstack based on Cu in combination with thin Al layers. We investigate the sheet resistance at different annealing temperatures in samples with varying Al layer thicknesses up to 10 nm. The power durability of samples with a very thin Al layer has been increased by ≈ 2 dBm compared with pure Cu metallization. TEM investigation on these samples also shows their thermal stability (after annealing) up to 450°C.

Heavy metal effects on P, Ca, Mg, and total protein contents in embryonic pleopodal eggs and stage-1 juveniles of freshwater crayfish Astacus leptodactylus (Eschscholtz, 1823)

To determine the potential biochemical effects of heavy metal pollution on aquatic organisms, pleopodal eggs, and stage-1 juveniles of the freshwater crayfish, Astacus leptodactylus (Eschscholtz, 1823), was exposed to a non-essential (Cd) and an essential (Cu) metal, either singly or in combination. Three different sublethal doses (0.1, 0.5, and 1 ppm) and 1 interaction dose (0.1 ppm Cu + 0.1 ppm Cd) were used to evaluate the accumulation and toxicity. The effects of 2 doses of metals on P, Ca, total protein, and Mg contents in the embryonic pleopodal eggs and in stage-1 juveniles were examined by an autoanalyzer. The same analyses were also performed on recently spawned eggs through the transition to the first juvenile stage (3 weeks). Ten eggs or stage-1 juveniles were sampled during the 3-week period to measure the bioaccumulation of metals. Cd and Cu levels in the eggs and recently spawned eggs were determined by flame atomic absorption spectrophotometer (FAAS). The results showed that both Cd and Cu accumulated in eggs and in stage-1 juveniles. The results also indicated that metal interactions also occurred, which in this case were probably antagonistic. A comparison of the effects of Cd alone with those of Cd+Cu in combination showed that the mixture was more toxic than Cd alone, but not more toxic than Cu alone. Cd also affected the Ca level in the eggs. The level of Mg increased, while the levels of P, Ca, and total protein decreased in pleopodal eggs exposed to different doses of Cu and Cd. All biochemical parameters and protein levels measured were affected by both metals.

Development of post-CMP cleanup processing for Cu/low-k devices

In recent years, Cu/low-k damascene (buried interconnects) processing, which uses Cu interconnects with low-dielectric-constant (low-k) films, has emerged as a way to satisfy the requirements for making devices ultrasmall, high-speed, and usable in ultralarge-scale integration (ultra-LSI). However, the use of Cu in combination with new materials to make the low-k films has led to difficulties in developing a process for cleaning after post-chemical-mechanical planarization (CMP). One of these problems is the presence of hydrophobic residuals on the low-k films, for whose removal many slurries (polishing agents) and cleaning fluids have been developed. In our work, we have combined these slurries and cleaning fluids, and investigated the effectiveness of the combinations in cleaning low-k films, allowing us to develop an optimum process. We determined the defect counts for TEOS, Cu, and two kinds of low-k films, and measured the level of contamination of the low-k film contaminant by spots of Cu, from which we identified cleaning fluid that performed best. We also confirmed that the performance of the cleaning fluids was different depending on the choice of slurry. We then used our optimum process to formulate a fabrication scheme for devices with the Cu/low-k structure, fabricated a set of devices, and investigated their electrical characteristics. Because of the significant reduction we observed in leakage currents between circuit lines to below 10−9 to 10−10A/m, we argue that our process can be used to fabricate ultra-LSI device ensembles under real conditions. © 2006 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 89(11): 19–30, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.20187