Copper Absorption Research Articles

Influence of electrical fields enhanced phytoremediation of multi-metal contaminated soil on soil parameters and plants uptake in different soil sections

The influence of electrical fields on phytoremediation of multi-metal (Cd, Cu, and Zn) naturally contaminated soils has been investigated based on different soil sections. After ryegrass and hybrid penisetum were sowed for 30 d, electrical fields were applied during 30 days with the switching polarity every 30 min and continuing for 16 h d−1. After electrokinetic (EK) assisted phytoremediation process, soil electrical conductivity (EC) in anode section and available soil potassium (K) in cathode section were obviously elevated. Plants biomass in middle and cathode sections were increased in both plants, especially in middle section the overall biomass of hybrid penisetum increased by 68.8%. The influence of electrical field on the contents of heavy metals in plants was different depending on the species of plants, kind of heavy metals and soil section. For Cd, Cu, and Zn co-contaminated soils, shoot metals accumulation in middle section in both plants were improved at least about 20% (with the exception of Zn in ryegrass). Electrical fields had the most significant effect on copper absorption by ryegrass and shoot Cu accumulation were elevated 32.5% in all the section. The soil EC maybe an important factor that affected electrical fields enhanced plants growth, plant metals concentrations and remediation efficiency.

Dietary Iron Intake in Excess of Requirements Impairs Intestinal Copper Absorption in Sprague‐Dawley Rat Dams, Causing Copper Deficiency in Neonatal Pups

Consumption of a high-iron diet by previously iron-deficient rat dams causes copper insufficiency; however, pathophysiological outcomes in their offspring are unknown. We hypothesized that high-iron consumption by dams would also lead to copper depletion in suckling pups. Accordingly, 8-9-week-old, pregnant Sprague-Dawley rats were randomized and initially fed a low-Fe diet for ≍7 days (to induce iron deficiency), and then switched to one of five AIN-93G-based diets, with variable iron levels (normal [80 ppm] to high [up to 1600 ppm]) and marginal copper content (2 ppm; normal is 6-7 ppm). Dams were fed these diets throughout the remainder of pregnancy and during lactation, until the termination of the experiments (when suckling pups were 13-15 days of age). Subsequently, hematological parameters and serum and tissue iron concentrations were measured, and copper biomarker analyses were performed. Intestinal 64Cu absorption and tissue distribution in dams, and 64Cu delivery to the suckling pups, were also assessed. Results showed that serum para-phenylenediamine (pPD) oxidase activity (reflecting serum ceruloplasmin [Cp]) was suppressed (p<0.05) in dams consuming 5-fold excess iron and in pups suckling dams that consumed iron at 10-fold excess. Hepatic nonheme iron concentrations increased in dams and pups (p<0.05) as dietary iron levels increased (possibly due to inhibition of Cp activity, which is required for iron release from hepatocytes). When dams consumed iron at 20-fold above requirements, pup growth was impaired (p<0.05), possibly due to copper depletion, as also indicated by decreases in erythrocyte SOD activity (which accurately reflects copper status) (p<0.05). Moreover, in iron-supplemented dams, intestinal copper (64Cu) absorption and 64Cu activity in blood, liver, and spleen were all decreased (p<0.05). A similar trend was also noted in pups suckling dams consuming exces iron, with 64Cu accumulation in blood, liver, and spleen (p<0.05) being lower than in controls. We conclude that maternal intake of excessive iron (~10-fold above the dietary recommendation) impairs absorption of dietary copper and concomitantly depletes copper in neonatal pups. Low milk copper content was the most likely explanation for this outcome, although this remains to be experimentally proven.

Intestinal uptake of Cu by processes that do not involve copper transporter 1 (CTR1), as determined with Caco2 cell monolayers

Dietary copper absorption across the apical brush border of intestinal cells involves several uptake systems, yet in mammals, only one gene product (CTR1) has as yet been identified as specific for copper uptake across the cell plasma membrane of intestinal and other cells. Some studies have suggested that the important iron uptake system, divalent metal transporter 1 (DMT1), is also involved, and yet another, uncharacterized chloride-dependent system has been implicated. CTR1 takes up Cu(I), and it is generally accepted that dietary copper is first reduced by cell surface reductases before entering the enterocyte. Uptake of Cu(I) by CTR1 is inhibited by Ag(I), while Fe(III) and Cu(II) compete for reduction by the reductases in the brush border. Using Caco2 cell monolayers with tight junctions grown in bicameral chambers, we determined that, whether given as Cu(I) or Cu(II), only about one third of copper uptake was inhibited by an excess of Ag(I), implying that CTR1 accounts for only a portion of intestinal copper uptake. Rates of Cu uptake were measured by following accumulation of radioactive Cu over 60 min in cells and the basal medium (equivalent to blood fluid) after application of 67Cu-labeled Cu(II)-nitrilotriacetate (5 uM) to the apical surface, and were calculated in terms of % dose/h/mg cell protein. Our finding implied that CTR1 does not account for most of the uptake carried out by the enterocytes. Measuring uptake of Cu(II) in the presence of an excess of Fe(III) – to prevent reduction of Cu(II), failed to inhibit copper uptake, implying that not all copper needs to be reduced prior to uptake. To further investigate the chloride-dependent process, reported by Zimnicka et al.[1]) the effects of substituting sulfate for chloride in the culture medium was examined. Chloride-dependent uptake was measured by the fall in uptake rate when sulfate was substituted for chloride, and the effects of substituting with other halides was also examined. We found that substitution of sulfate for chloride reduced rates of copper uptake about 30%, and that the effects of Ag(I) and sulfate substitution were additive. Substituting bromide for chloride made no difference, while iodide substitution actually doubled uptake rates. Thus, a halide dependent system may also be prominent in mediating intestinal copper absorption. Effects of altering the nutritional iron status of the Caco2 cell monolayer was also examined. Pretreatment with excess iron (3 days with 5 uM ferric ammonium citrate) reduced expression of CTR1 and DMT1 mRNAs (determined by qPCR relative to 18S rRNA) but had little effect on rates of copper uptake. However, 48 h depletion of iron with desferrioxamine increased rates of copper uptake. As expected, this also increased expression of mRNA for DMT1. However, the iron deficiency also enhanced expression of CTR1. We conclude that at least in this intestinal model, CTR1 and a halide-dependent uptake process each account for about one third of Cu uptake; that CTR1 expression is enhanced by iron deficiency – which would explain increased uptake of copper in that condition; and that a Cu(II) uptake system may also be present. [1]Zimnicka et al. (2011) Am J Physiol Cell Physiol 300: C588–C599.

Defining Post‐transcriptional Regulation of the Copper Transporter ATP7A in Skeletal Muscle Cells

Copper is an important trace nutrient that functions as an enzyme cofactor and signaling molecule. Copper is also toxic, so intracellular copper must be tightly regulated by transporters and chaperones. In most cells, copper export is mediated by the trans-Golgi copper transporter, ATP7A, which provides copper to secreted cupro-enzymes. Loss of ATP7A causes Menkes disease, wherein dietary copper absorption is impaired, cellular copper homeostasis is disrupted, and secreted cupro-enzymes are not supplied with copper. One symptom of Menkes disease is muscle weakness, which is largely unexplained. Skeletal muscle is a post-mitotic tissue comprised of multi-nucleated myofibers and can be regenerated by a closely-associated pool of stem cells. Few studies have focused on ATP7A in skeletal muscle. Our previous work showed that total cellular copper, ATP7A levels, and Atp7a mRNA stability increase during muscle cell differentiation. Here, we used an immortalized muscle cell line, C2C12, to demonstrate that Atp7a mRNA is stabilized in higher copper concentrations in undifferentiated muscle cells. We used a candidate-based approach to identify RNA binding proteins that regulate the Atp7a mRNA. Candidates were chosen based on previously described interaction with Atp7a mRNA and other copper homeostasis gene transcripts, their potential ability to bind copper, and their role in muscle development. With these criteria, we identified PTBP1 as a candidate. Using RNA immunoprecipitation, we confirmed that PTBP1 binds Atp7a mRNA in C2C12 cells. We used siRNA to knock down Ptbp1 in C2C12 myoblasts and detected increased Atp7a mRNA and protein levels. Our work further defines the post-transcriptional regulation of Atp7a and identifies PTBP1 as a potential regulator of copper homeostasis.

Bandgap Energy of TiO₂/M-Chlorophyll Material (M=Cu²⁺, Fe³⁺)

The bandgap energy (Egap) of TiO2 material modified with metal-chlorophyll complex compounds (M = Cu2+, Fe3+) was observed. Chlorophyll (Chl) was isolated from cassava leaves, and its UV-Vis spectra showed absorption peaks in the Soret band region (410 nm) and in the Q band region (665 nm), which is the typical peak of chlorophyll. Copper(II)-chlorophyll complex was prepared from the reaction between chlorophyll and CuSO4.5H2O, while the iron(III)-chlorophyll was synthesized from chlorophyll and FeCl3.6H2O in methanol solvent under reflux at 65°C. The presence of copperand iron metals in the chlorophyll metal complexes was identified using Atomic Absorption Spectroscopy in methanol solution. The absorption of copper measured in Cu2+-Chl was 0.0488 (0.4805 mg/L), while the iron atom in Fe3+-Chl was 0.0050 (0.0195 mg/L). The UV-vis spectra demonstrate the hypsochromic shift of the Soret band to 405 nm (Cu2+-Chl) and 402 nm (Fe3+-Chl). The Infrared spectra of chlorophyll after being complexed with copper(II) shows the increase of vibrational absorption wavenumber of the C=N group from 1225.06 cm-1 to 1241.94 cm-1 indicates the coordination of the metal ion on the N atom in the pyrrole ring. The shift in the absorption band on the Fe3+-Chl spectrum was seen for the C=O ester group from 1720.49 cm-1 to 1721.10 cm-1 indicating the metal ion bonding in the C=O group of esters. The DR-UVis analysis of TiO2/metal-chlorophyll shows a bathochromic shift towards the visible light region. By using the Tauc plot method, it was observed that the Egap of TiO2 reduces from 3.08 eV to 2.89 eV and 2.93 eV in the compound of TiO2/Cu2+-Chl and TiO2/Fe3+-Chl, respectively.

Сравнительный анализ химического состава растительного сырья некоторых представителей родов Narcissus L. и Camassia Lindl.

Abstract. Purpose. Heavy metals can have a negative effect on plants, animals and humans if their concentration exceeds certain limits. Therefore, it is important to establish the characteristics of the accumulation of heavy metals and to determine the elemental composition of aboveground (leaves) and underground (bulbs) organs in plant samples of 8 varieties of Narcissus hybridus hort. (Actaea, Arctic Gold, Cassata, Quail, Sir Winston Churchill, White Lady, Calgary, Pink Parasol) and Camassia cusickii S. Wats. in the urbanized environment of the city of Ufa (Republic of Bashkortostan). Methods. The study of the elemental composition of the samples was carried out according to the method of quantitative chemical analysis “Determination of As, Pb, Cd, Sn, Cr, Cu, Fe, Mn and Ni in laboratory samples of food products and food raw materials by the atomic absorption method with electrothermal atomization No. M-02-1009-08”. Scientific novelty. This work is the first to analyze the results of the content of individual elements in aboveground and underground organs in samples of cultivated floral and ornamental plants in the forest-steppe zone of the Bashkir Ural. Results. It was found that the content of nickel, copper, cadmium, lead, magnesium, iron, chromium in all the samples studied does not exceed the standards specified in the State Pharmacopoeia of the Russian Federation (SP RF). The arsenic content exceeds the standards specified in the SP RF by 3.4 times. Revealed a high intensity of biological absorption of copper. The peculiarity of the accumulation of individual elements by different taxa of the studied plants is noted. It has been established that the concentrations of As, Cu, Pl, Mn, Fe in the aboveground organs are higher than in the underground part of plants; the ratio of the content of Ni, Cr, Cd in aboveground and underground organs is the same. As a result of these studies, it was recommended to use the studied cultivars as a phytoremediator of arsenic.

Phytoremediation Potential of E. camaldulensis and M. alba for Copper, Cadmium, and Lead Absorption in Urban Areas of Faisalabad City, Pakistan

Soil pollution by heavy metals from industrial and anthropogenic activities is prevalent and a serious threat to ecosystems and humans. To immobilize heavy metal toxicity using trees is an effective and low-cost method for soil remediation. The present study was aimed to assess the most suitable bioindicator of trace elements including copper (Cu), cadmium (Cd), and lead (Pb) among Morus alba and Eucalyptus camaldulensis plant species at seven different sites in Faisalabad, an industrial city of Pakistan during the summer and winter seasons. Samples from the leaf, bark, deposited dust, and soil of both subjected species was collected for the assessment of metals accumulation. The recorded data showed that the trend of heavy metal concentration in soil, deposited dust, bark, and the leaf of both species was Pb > Cu > Cd. Generally, the maximum concentration of Cd, Cu, and Pb was recorded at the building material processing area during both seasons in both subjected species. Moreover, the highest concentration of Cd and Pb was recorded in leaf samples, while the highest concentration of Cu was recorded in dust samples. These results suggesting the idea that tree leaves can be used as a good indicator of Cd, and Pb concentration. In the case of Cu, a highly significant correlation (P < 0.05) was found between Cu concentration in deposited dust and leaves of both species during both growing seasons, indicating that the main source of Cu accumulation is atmospheric dust. Moreover, the summer season was more sensitive for the exposure of Cd, Cu, and Pb while, M. alba was proved as a good bioindicator and bioaccumulator for all recorded heavy metals during both seasons. According to the obtained results, M. alba trees are more likely to capture Cd, Cu, and Pb from the air, so planting these trees in industrial areas with such atmosphere pollutants would be beneficial.

534 Persistent Copper and Zinc Deficiency in Excess of 30 Days Post Burn Injury

Abstract Introduction Copper and zinc deficiencies are common after burn injury, with the lowest levels usually occurring within seven days. Both trace elements are important for wound healing, but due to competition for absorption in the small intestine, oral replacement of zinc and copper may not be sufficient. Nutritional guidelines recommend copper and zinc replacement for up to 30 days, but little data is available to guide long-term trace element replacement. Methods This case series includes four patients with 15% or larger total body surface area burns who had hypocupremia at least 30 days after admission despite receiving at least the recommended daily allowance of copper via tube feeds. Results In two patients, copper levels increased following discontinuation of oral zinc tablets. However, one patient had continued hypocupremia and increasing zinc levels while receiving zinc only from tube feeds, suggesting this amount of zinc may decrease dietary copper absorption. For one patient with 95% TBSA burns, hypocupremia was associated with polyneuropathy and osteopenia. Another patient experienced an acute drop in zinc levels associated with bacteremia and sepsis. Conclusions In this case series, hypocupremia was associated with anemia and zinc deficiency with poor wound healing. Additional multicenter practice reviews of copper and zinc supplementation in burn centers would be beneficial.

Dietary Iron Intake in Excess of Requirements Impairs Intestinal Copper Absorption in Sprague Dawley Rat Dams, Causing Copper Deficiency in Suckling Pups

Physiologically relevant iron-copper interactions have been frequently documented. For example, excess enteral iron inhibits copper absorption in laboratory rodents and humans. Whether this also occurs during pregnancy and lactation, when iron supplementation is frequently recommended, is, however, unknown. Here, the hypothesis that high dietary iron will perturb copper homeostasis in pregnant and lactating dams and their pups was tested. We utilized a rat model of iron-deficiency/iron supplementation during pregnancy and lactation to assess this possibility. Rat dams were fed low-iron diets early in pregnancy, and then switched to one of 5 diets with normal (1×) to high iron (20×) until pups were 14 days old. Subsequently, copper and iron homeostasis, and intestinal copper absorption (by oral, intragastric gavage with 64Cu), were assessed. Copper depletion/deficiency occurred in the dams and pups as dietary iron increased, as evidenced by decrements in plasma ceruloplasmin (Cp) and superoxide dismutase 1 (SOD1) activity, depletion of hepatic copper, and liver iron loading. Intestinal copper transport and tissue 64Cu accumulation were lower in dams consuming excess iron, and tissue 64Cu was also low in suckling pups. In some cases, physiological disturbances were noted when dietary iron was only ~3-fold in excess, while for others, effects were observed when dietary iron was 10–20-fold in excess. Excess enteral iron thus antagonizes the absorption of dietary copper, causing copper depletion in dams and their suckling pups. Low milk copper is a likely explanation for copper depletion in the pups, but experimental proof of this awaits future experimentation.

Impact of Wastewater and Canal Water Irrigation on the Accumulation of Copper in Maize and Millet of Different Districts of Punjab Pakistan

In current work, we examined the absorption of metal Copper in generally grown food crops (Maize &amp; Millet), cultivated in the waste water irrigated different Districts of Punjab, Pakistan. Analyzed samples of Water, Soil, shoot and grain were processed through atomic absorption spectrometric method. Our findings of Copper in water and Shoot were highest for Millet of Sargodha, irrigated with wastewater (1.69 mg/kg and 1.43 mg/kg respectively). In soil and grain samples maximum absorption of Cu was obtained in the waste water irrigated Maize (Sargodha) and Millet (Sheikhupura). Overall, Cu level was within the acceptable parameters set by FAO/WHO (2001). In this study, we also find out different indices such as Enrichment factor, Translocation factor, Pollution Load Index, Bio-concentration factor, Daily intake of metal and Health Risk Index. The study determined that frequently intake of waste watered forages in experimenting zone may carry possible health uncertainties in inhabitants.

Preparation, Two-Photon Absorption, and Bioimaging Application of a Curcumin-Based Copper(II) Complex

A new multi-branched model Cu(II) complex based on curcumin, namely CuL2(I) (НL = (1E,4Z,6E)-1,7-bis(4-(4-bromobutoxy)-3-methoxyphenyl)-5-hydroxyhepta-1,4,6-trien-3-one, C29H34O6Br2), was prepared and its two-photon absorption (TPA) properties were described in the femtosecond regime. The experimental results showed that complex I exhibited relatively strong and wide-dispersed two-photon activities in the near-infrared (NIR) regime and the calculated TPA cross section of complex I was as high as 872 GM (1 GM = 10−50 cm4 s photon−1) in DMF. Additionally, complex I revealed its potential application as a biological fluorescent probe due to its good photo-physical properties and low cytotoxicity, as well as excellent stability and specificity for optical imaging of tumors. Complex I was characterized by single crystal X-ray diffraction too (CIF file CCDC no. 1412447).

Accumulation of heavy metals in the organs of herbaceous plants

The purpose of the work is to establish the characteristics of the accumulation of heavy metals of aboveground and underground organs in plant samples of 8 varieties of Narcissus hybridus and Camassia cusickii in the urbanized environment of the city of Ufa. The study of the elemental composition of the samples was carried out according to the method of quantitative chemical analysis ‘Determination of As, Pb, Cd, Sn, Cr, Cu, Fe, Mn and Ni in laboratory samples of food products and food raw materials by the atomic absorption method with electrothermal atomization’. It was found that the content of nickel, copper, cadmium, lead, magnesium, iron, chromium in all the samples studied does not exceed the standards specified in the State Pharmacopoeia of the Russian Federation (SP RF). The arsenic content exceeds the standards specified in the SP RF by 3.4 times. Revealed a high intensity of biological absorption of copper. It has been established that the concentrations of As, Cu, Pl, Mn, Fe in the aboveground organs are higher than in the underground part of plants; the ratio of the content of Ni, Cr, Cd in aboveground and underground organs is the same.

Regulation of murine copper homeostasis by members of the COMMD protein family.

ABSTRACTCopper is an essential transition metal for all eukaryotes. In mammals, intestinal copper absorption is mediated by the ATP7A copper transporter, whereas copper excretion occurs predominantly through the biliary route and is mediated by the paralog ATP7B. Both transporters have been shown to be recycled actively between the endosomal network and the plasma membrane by a molecular machinery known as the COMMD/CCDC22/CCDC93 or CCC complex. In fact, mutations in COMMD1 can lead to impaired biliary copper excretion and liver pathology in dogs and in mice with liver-specific Commd1 deficiency, recapitulating aspects of this phenotype. Nonetheless, the role of the CCC complex in intestinal copper absorption in vivo has not been studied, and the potential redundancy of various COMMD family members has not been tested. In this study, we examined copper homeostasis in enterocyte-specific and hepatocyte-specific COMMD gene-deficient mice. We found that, in contrast to effects in cell lines in culture, COMMD protein deficiency induced minimal changes in ATP7A in enterocytes and did not lead to altered copper levels under low- or high-copper diets, suggesting that regulation of ATP7A in enterocytes is not of physiological consequence. By contrast, deficiency of any of three COMMD genes (Commd1, Commd6 or Commd9) resulted in hepatic copper accumulation under high-copper diets. We found that each of these deficiencies caused destabilization of the entire CCC complex and suggest that this might explain their shared phenotype. Overall, we conclude that the CCC complex plays an important role in ATP7B endosomal recycling and function.

Recovery of valuable metals from spent mobile phone printed circuit boards using biochar in indirect bioleaching

Improving the bioleaching efficiency of metals from spent mobile phone printed circuit boards (PCBs) in a short time has been of major interest in recent years. In this paper, a novel cheap catalyst (oak wood biochar) was used to improve the copper and nickel bioleaching efficiency from spent mobile phone PCBs. The biochar was derived from oak wood through slow pyrolysis at a low temperature of 500 °C for 1h. The results of RSM optimization indicated that the optimum conditions to maximize copper and nickel recovery were 1.6 g/L biochar and 16 g/L pulp density. The findings indicated that compared to without the presence of biochar, the leach yields of copper and nickel were high. As much as 98% of copper and 82% of nickel were leached by indirect bioleaching under optimum conditions. The better performance in the presence of biochar is due to both galvanic interactions between biochar and solid waste. The biochemical characterization of bioleaching solution suggested that the high concentration of biochar (> 1.6 g/L) led to copper absorption by functional groups on the surface of biochar. Compared to chemical leaching, the bioleaching has better performance. Under optimum conditions, the copper and nickel recovery by indirect bioleaching was 36% and 64% more than that by chemical leaching. Also, it is found that biochar has a positive effect on the chemical leaching process. Therefore, in this paper, the function of biochar was elaborated not only in bio-hydrometallurgy but also in the hydrometallurgy process.

The copper(II)-binding tripeptide GHK, a valuable crystallization and phasing tag for macromolecular crystallography.

The growth of diffraction-quality crystals and experimental phasing remain two of the main bottlenecks in protein crystallography. Here, the high-affinity copper(II)-binding tripeptide GHK was fused to the N-terminus of a GFP variant and an MBP-FG peptide fusion. The GHK tag promoted crystallization, with various residues (His, Asp, His/Pro) from symmetry molecules completing the copper(II) square-pyramidal coordination sphere. Rapid structure determination by copper SAD phasing could be achieved, even at a very low Bijvoet ratio or after significant radiation damage. When collecting highly redundant data at a wavelength close to the copper absorption edge, residual S-atom positions could also be located in log-likelihood-gradient maps and used to improve the phases. The GHK copper SAD method provides a convenient way of both crystallizing and phasing macromolecular structures, and will complement the current trend towards native sulfur SAD and MR-SAD phasing.

Molybdenum Exposure in Drinking Water Vs Feed Impacts Apparent Absorption of Copper Differently in Beef Cattle Consuming a High-Forage Diet.

Twelve Angus steers were utilized to investigate the influence of molybdenum (Mo) in drinking water or feed on apparent absorption and retention of copper (Cu) and Mo. Steers were fed a low-quality grass hay diet for 14days. Steers were then housed in individual metabolism stalls and blocked by body weight and dry matter intake (DMI) and randomly assigned within block to one of three treatments. Treatments consisted of (1) control (no supplemental Mo), (2) 5.0mg Mo/kg DM from sodium molybdate dihydrate (Mo-diet), and (3) 1.5mg Mo/L from sodium molybdate dihydrate delivered in the drinking water (Mo-water). Total fecal and urine output were then collected for 5days. Dry matter, Cu and water intake, and DM digestibility were similar across treatments. Molybdenum intake was greater (P < 0.05) in Mo-water and Mo-diet steers when compared to controls but similar between Mo-water and Mo-diet steers. Apparent absorption and retention of Cu were greater (P < 0.05) in controls when compared to Mo-diet supplemented steers. Apparent absorption and retention of Cu in steers in the Mo-water treatment did not differ from controls or those receiving the Mo-diet. Molybdenum-diet and Mo-water supplemented steers had similar apparent absorption and retention of Cu. Apparent absorption and retention of Mo (% of Mo intake) was greater in controls when compared to Mo-supplemented steers. These data indicate that Mo consumed in water may impact Cu absorption and retention to a lesser extent than Mo supplemented in the diet.

Highly conductive and strong CuSn0.3 alloy processed via laser powder bed fusion starting from a tin-coated copper powder

Despite the high demand, the successful fabrication of fully dense, highly conductive, and strong copper components via laser powder bed fusion (LPBF) is not readily evident. This is mainly due to the low optical absorption of copper, which inhibits the complete melting of copper powders when using commercially available fiber-laser-based LPBF machines. Accordingly, this article proposes a novel approach of using optically absorptive metal-coated copper powders for the fabrication of fully dense, highly conductive, and strong copper components via LPBF. To validate this approach, the surface of the copper powder is modified by applying a very thin (62 ± 14 nm) layer of metallic tin via an immersion plating technique. The application of only a 0.28 wt% of metallic tin coating significantly improved the room temperature powder optical absorption by ∼170 % at the fiber laser wavelength. Consequently, crack-free and fully dense copper parts combining high thermal conductivity of 334 ± 4 (W/(m·K)) and electrical conductivity of 80 ± 1 % international annealed copper standard (%IACS) with a good tensile strength of 256 ± 14 MPa, yield strength of 203 ± 4 MPa, and ductility of 21 ± 2 % have been fabricated using a fiber laser with an output laser power of 500 W. Furthermore, the article also describes the negative influence of the presence of a high amount of (0.091 wt%) sulfur, which originates from the organic additives during sub-optimal coating conditions, on the LPBF processing behavior of CuSn alloys. As such, high sulfur-containing tin-coated copper powders do not allow the fabrication of fully dense parts due to the occurrence of solidification cracks and the formation of pores. Subsequently, the optimum tin coating methodology, which limits the amount of sulfur below 0.0025 wt%, is described. The use of sulfur-free powder is recommended for the successful LPBF processing of fully dense parts made of copper and copper alloys.

МОДЕЛЮВАННЯ ПОГЛИНАННЯ МІДІ СІЛЬСЬКОГОСПОДАРСЬКИМИ РОСЛИНАМИ В СУЧАСНИХ УМОВАХ ВИРОЩУВАННЯ

Моделювання є одним із основних методів дослідження у сучасній екологічній науці. В рамках роботи, за допомогою математичної моделі, яка дозволяє урахувати рослинні, грунтові, кліматичні та агротехнічні характеристики, виконано моделювання поглинання одного з найбільш токсичних важких металів, до якого відноситься мідь, рослинами цукрового буряку в умовах Херсонської області. Розрахунки проводилися за осередніними даними багатолітнього періоду спостереження, з урахуванням вмісту міді у орному шарі грунту( чорноземи південні), особливостей поглинання міді рослиною та умов вирощування. При цьому виконано аналіз вмісту міді за останні 23 роки . Відзначено, що за останні 5 років спостерігається значне зменшення вмісту міді у грунтах Херсонської області, мабуть за рахунок зменшення використання мінеральних добрив та хімічних засобів захисту рослин, до складу яких входить велика кількість важких металів ( у тому числі міді). Моделювання поглинання виконано для однієї з найбільш розповсюджених та культивуємих сільськогосподарських рослин, до якої належить цукровий буряк. Це питання є досить актуальним завдяки тому, що продуктом переробки цієї культури є продукти харчування, які можуть вміщувати важки метали і визначати екологічну чистоту продукції.

Zinc Therapy in Early Alzheimer's Disease: Safety and Potential Therapeutic Efficacy.

Zinc therapy is normally utilized for treatment of Wilson disease (WD), an inherited condition that is characterized by increased levels of non-ceruloplasmin bound (‘free’) copper in serum and urine. A subset of patients with Alzheimer’s disease (AD) or its prodromal form, known as Mild Cognitive Impairment (MCI), fail to maintain a normal copper metabolic balance and exhibit higher than normal values of non-ceruloplasmin copper. Zinc’s action mechanism involves the induction of intestinal cell metallothionein, which blocks copper absorption from the intestinal tract, thus restoring physiological levels of non-ceruloplasmin copper in the body. On this basis, it is employed in WD. Zinc therapy has shown potential beneficial effects in preliminary AD clinical trials, even though the studies have missed their primary endpoints, since they have study design and other important weaknesses. Nevertheless, in the studied AD patients, zinc effectively decreased non-ceruloplasmin copper levels and showed potential for improved cognitive performances with no major side effects. This review discusses zinc therapy safety and the potential therapeutic effects that might be expected on a subset of individuals showing both cognitive complaints and signs of copper imbalance.

Sulphide‐induced stress corrosion cracking and hydrogen absorption of copper in deoxygenated water at 90°C

AbstractStress corrosion cracking (SCC) of oxygen‐free phosphorous‐alloyed copper was investigated in sulphide‐ and chloride‐containing deoxygenated water at 90°C with sulphide concentrations of 0.001 and 0.00001 M. Several intergranular defects were found in the specimen exposed to the high sulphide environment. Similar defects were not found in the low sulphide environment, where only slight corrosion on grain boundaries and slip lines occurred. Hydrogen content measurements show an increase in hydrogen uptake of the plastically deformed specimens, which is dependent on the sulphide concentration and on plastic deformation of copper. However, the highest hydrogen content was measured in friction stir welds, welded in air without shielding gas, and tested in the high sulphide environment. The embedded oxide particles in the weld metal act as local hydrogen trapping sites and selectively react with the sulphide solution. A relatively thick air‐formed oxide film covers the copper canisters when deposited, which transforms into a sulphide film in the repository conditions. Thus, some of the coupon specimens were pre‐oxidised. The conversion of the pre‐existing Cu2O film into Cu2S film occurs quickly and the transformation is almost 100% efficient. The structure and properties of the Cu2S films, susceptibility of copper to sulphide‐induced SCC and hydrogen uptake of copper in reducing, anoxic repository conditions are discussed.