Proportion Of Zn Research Articles

The Chemical and Rheological Properties of Corn Extrudates Enriched with Zn- and Se-Fortified Wheat Flour

This paper analyzed the influence of the addition of Zn- and Se-fortified wheat flour to corn extrudates on viscosity, total starch content, starch damage, and bioavailability of zinc and selenium. Fortified wheat flour was added to corn grits in 90:10, 80:20, 70:30, and 60:40 ratios at three extrusion temperature profiles: 140/170/170 °C, 150/180/180 °C, and 160/190/190 °C. Viscosity values decreased significantly at different extrusion temperature profiles and at different proportions of wheat. The extrusion process increased the starch content, regardless of the extrusion temperature, and decreased it by adding different proportions of flour enriched with zinc and selenium. The starch damage increased with extrusion, without significant changes with extrusion temperature increment. The addition of different proportions of Zn- and Se-fortified wheat flour reduced starch damage values proportionally to the added content of enriched wheat. Increasing the temperature and the proportions, the total zinc content in the extrudates increased. Zinc bioavailability increased with increasing extrusion temperature. As for selenium, the total content increased by proportion increment but decreased with an increase in the extrusion temperature, though there were no significant differences in selenium bioavailability regardless of changes in extrusion temperature or the proportion of enriched wheat.

Zinc speciation in highly weathered tropical soils affected by large scale vegetable production

Agriculture in highly weathered tropical soils often requires considerable application of lime and fertilizers to ensure satisfactory plant nutrient levels. The consequences of these continue long-term applications is not well understood may induce changes in soil chemical properties, the abundance, and speciation of potentially toxic trace element and as well as of micronutrients in agriculture soils. In this study, we evaluated the adsorption (at pH 5) and speciation of Zn in tropical soils (both agricultural and native vegetation) as a function of fertilization and contact time using chemical fractionation analyses and X-ray absorption spectroscopy. The soils overall had high Zn adsorption capacities (∼ 700 mg kg-1), but the agricultural soil was approximately 30 % higher than of the soil under native vegetation, and the proportion of Zn in the mobile fraction was 35 % in native vegetation and 21 % in agricultural soils. Zn speciation via linear combination analysis showed a strong relationship with soil mineralogical composition and reveled that Zn associated with organic matter decreased while Zn associated with P increased after the conversion of soils from native vegetation to highly fertilized soil. Aluminosilicate soil minerals were identified as major sinks of soil Zn, accounting for 34 % of total Zn retention regardless of soil origin and land use. Association of Zn with phosphate (i.e., hopeite) was observed in the agricultural soil samples, which might be an unexpected Zn-bearing mineral in highly weathered tropical soils and could have impacts on Zn plant nutrition.

Mechanical properties of larval mouthparts of the antlion Euroleon nostras (Neuroptera: Myrmeleontidae) and their correlation with cuticular material composition

The diversity of insects can be explained by their ability to fill various ecological niches, which includes the foraging from diverse sources. The cuticle-based feeding structures interact with the food and show adaptations in shape, material composition and mechanical properties to it. In this study, we focus on the mouthparts of a very prominent ambush predator, the antlion larvae of Euroleon nostras. By nanoindentation, we tested the hardness and the Young’s modulus of the mouthparts, which are significantly harder and stiffer than other insect cuticle structures. To gain insight into the origins of the high values, we studied the degree of tanning using confocal laser scanning microscopy. Additionally, we determined the content of transition and alkaline earth metals by energy dispersive X-ray spectroscopy. We found that the proportions of Zn, Mn, Fe, Cu, Ca, Mg, and Si correlate with the mechanical property values. We also conducted experiments on the breaking stress, the puncturing and biomechanical behaviour of the jaws, which highlighted their extraordinary strength. These findings are not only valuable for biologists, but also for material scientists, as they contribute to our understanding of the origins of mechanical property heterogeneities in insect cuticle.

Boosting photocatalytic hydrogen production based on amino acid derived Zn-MOF/CdS composite photocatalysts

The utilization of solar energy to decompose water and produce hydrogen is one of the important strategies to solve the problems of ecological environment and energy crisis. Herein, a series of CdS-modified Metal-Organic Frameworks (MOFs) composites Zn(LFor)-MOF/CdS were successfully prepared through the reaction of N-(4-pyridine-methyl)-l-valine·HCOONa (NaLFor), Zn acetates, and CdS nanoparticles. The composite Zn(LFor)-MOF/CdS exhibit a very high photocatalytic performance for hydrogen production from water cracking under visible light irradiation, which is superior to the pristine MOF and cadmium sulfide materials. The hydrogen production based on different proportions of Zn(LFor)-MOF/CdS materials were investigated, and the prepared Zn(LFor)-MOF/CdS (4:1) material showed excellent hydrogen evolution performance with the hydrogen yield reaching 267.6 μmol/h. Zn(LFor)-MOF/CdS (4:1) has a high photocurrent intensity, which can effectively inhibit the photoelectron-hole recombination, improve the electron-hole transport ability at the interface, accelerate the electron migration, which makes this material a high hydrogen production photocatalytic activity.

Properties of Cu/Zn+15%SAC0307+15%Cu/Al joints by different ultrasonic-assisted degrees

PurposeThis paper aims to investigate the effects of different ultrasonic-assisted loading degrees on the microstructure, mechanical properties and the fracture morphology of Cu/Zn+15%SAC0307+15%Cu/Al solder joints.Design/methodology/approachA new method in which 45 μm Zn particles were mixed with 15% 500 nm Cu particles and 15% 500 nm SAC0307 particles as solders (SACZ) and five different ultrasonic loading degrees were applied for realizing the soldering between Cu and Al at 240 °C and 8 MPa. Then, SEM was used to observe and analyze the soldering seam, interface microstructure and fracture morphology; the structural composition was determined by EDS; the phase of the soldering seam was characterized by XRD; and a PTR-1102 bonding tester was adopted to test the average shear strength.FindingsThe results manifest that Al–Zn solid solution is formed on the Al side of the Cu/SACZ/Al joints, while the interface IMC (Cu5Zn8) is formed on the Cu side of the Cu/SACZ/Al joints. When single ultrasonic was used in soldering, the interface IMC (Cu5Zn8) gradually thickens with the increase of ultrasonic degree. It is observed that the proportion of Zn or ZnO areas in solders decreases, and the proportion of Cu–Zn compound areas increases with the variation of ultrasonic degree. The maximum shear strength of joint reaches 46.01 MPa when the dual ultrasonic degree is 60°. The fracture position of the joint gradually shifts from the Al side interface to the solders and then to the Cu side interface.Originality/valueThe mechanism of ultrasonic action on micro-nanoparticles is further studied. By using different ultrasonic loading degrees to realize Cu/Al soldering, it is believed that the understandings gained in this study may offer some new insights for the development of low-temperature soldering methodology for heterogeneous materials.

Transformation of zinc oxide nanoparticles in the presence of aluminum oxide with pre-sorbed phosphorus ligands

Naturally occurring oxides could react with zinc oxide (ZnO) nanoparticles (NPs) and then change its transformation and toxicity to ecological receptors. The reaction may be affected by a variety of environmental factors, yet the relevant processes and mechanisms are limitedly investigated. Natural prevalent ligands, as an important factor, can sorb on natural oxide minerals and change its surface property, finally affecting ZnO NP transformation. This study investigated the interactions of ZnO NPs with phosphorus ligands (i.e., phytate and orthophosphate) pre-sorbed γ-alumina (γ-Al2O3) via batch experiments and multi-technique analyses. A limited amount of aqueous Zn2+ is observed when the concentration of ZnO NPs is relatively low (<64.8 mg L−1) in the presence of phytate pre-sorbed γ-Al2O3. Solid Zn(II) species includes binary/ternary surface Zn(II) complexes on γ-Al2O3 with minor amounts of zinc phytate precipitates. As the concentration of ZnO NPs increases, surface Zn(II) complexes gradually transform into zinc phytate and Zn−Al layered double hydroxide (Zn−Al LDH) precipitates. The quantitative analysis indicates that, as the concentration of ZnO NPs increases from 32.4 to 388.8 mg L−1, the proportion of Zn(II) species as binary/ternary surface complexes decreases from 81.9 to 30.2%; and the proportion as zinc phytate and Zn−Al LDH increases from 17.9 to 27.6% and 0 to 43.8%, respectively. The pre-sorption of orthophosphate can also inhibit ZnO NP transformation into Zn−Al LDH precipitates on γ-Al2O3. This study suggests that natural ligands pre-existed on natural oxide minerals could greatly influence the solubility, stability, transformation, and fate of easily dissoluble metal oxides (e.g., ZnO) in the environments.

Teksturalna i senzorska svojstva ekstrudiranih kukuruznih snack proizvoda s dodatkom pčenice obogaćane cinkom i selenom

The aim of this paper was to investigate the influence of Zn‐ and Se‐fortified wheat flour addition to the corn grits at 90:10, 80:20, 70:30, 60:40 ratios on the hardness, fracturability, expansion ratio, bulk density, color, and sensory attributes of the extrudates. Extrusion was performed at three temperature profiles: 140/170/170 °C, 150/180/180 °C, and 160/190/190 °C. With an increase in the proportion of Zn‐ and Se‐ fortified wheat flour and temperature increase, all observed physical characteristics of extrudates decreased. The lightness of all the samples increased after the extrusion. The total color change increased with the addition of Zn‐ and Se‐fortified wheat flour. Sensory characteristics showed that the samples with a lower percentage of added Zn‐ and Se‐fortified wheat flour had better scores and acceptability, compared to the samples with a higher fortification ratio.

Effect of zinc substitution on the physical and electrochemical properties of mesoporous SnO2 nanoparticles

In this work, the effect of substitution of zinc (Zn2+) ions on structural, optical, morphological and electrochemical properties of mesoporous tin dioxide (SnO2) nanoparticles (NPs) was analyzed. The XRD spectra revealed a significant reduction in crystallite size scale down from 17 to 39 nm when the proportion of Zn was increased. The Field Emission Scanning Electron Microscopy (FE-SEM) and transmission electron microscope (TEM) images authenticated the uniformity of the size and shape of as prepared Zn substituted SnO2 NPs. From the porosity measurements using N2 sorption isotherms, it was found that the synthesized particles were porous in nature and the corresponding BET surface area was found to increase with the increase in the dopant percentage and the BET surface area was found to vary in the range of 36–40 m2/g for higher percentage of dopants. The Electrochemical impedance spectroscopy (EIS) denoted a significant decrease in charge transfer resistance (RCT) indicating an improved electrochemical performance of the electrode.

Soil Nutrients Effects on the Performance of Durum Wheat Inoculated with Entomopathogenic Fungi

Entomopathogenic fungi (EFs) are widely used as biological control agents. However, some strains of Beauveria bassiana and Metarhizium brunneum can also promote plant growth and increase nutrient uptake. We examined the effects of soil properties on the performance of Triticum durum inoculated by seed dressing with these EFs and grown on 12 agricultural soils. The plants were supplied with all nutrients except P and Zn (essential for yield and the grain quality of wheat). Fungal inoculation increased the grain yield and harvest index significantly with B. bassiana (17% and 14%, respectively) but not with M. brunneum (6% and 6%, respectively). The increase in grain yield was positively and moderately correlated with the soil available phosphorus (POlsen) in plants inoculated with B. bassiana and with the soil content in poorly crystalline Fe oxides with M. brunneum. In addition, the increase in aerial dry matter resulting from inoculation with B. bassiana was negatively correlated with soil available Zn. Furthermore, the observed increase in grain yields due to fungal inoculation resulted in P and Zn grain dilution (grain nutrient concentrations decrease). Inoculation with B. bassiana increased grain Zn uptake and the proportion of Zn in grain relative to that in aerial dry matter. Success in the mutualistic relationship between EF and wheat plants depends on the fungal strain and soil properties.

Contamination and ecological risk assessment of the Red Sea coastal sediments, southwest Saudi Arabia

The level of heavy metals (HMs) in coastal sediments has attracted the environmental researchers due to their persistence, abundance, biomagnification and toxicity. The present study was conducted to assess the contamination and ecological risk assessment of HMs in Jazan coastal sediments, Red Sea, Saudi Arabia utilizing pollution indices and multivariate statistical analyses. A total of 32 surface samples were collected for Cu, Sb, Zn, Cr, Cd, Pb, Fe, Co, Ni, Al, and total organic matter analysis using an atomic absorption spectrophotometer. The results indicate the following descending order of metal concentrations: Al > Fe > Cr > Cu > Zn > Ni > Co > Pb > Cd > Sb. Average level of Cd is significantly higher than those from many neighboring and worldwide coastal sediments; and recorded very severe enrichment, severe contamination and very high risk in the investigated sediments. The pollution indices and statistical analyses revealed that proportion of Zn, Fe, Ni, Cr, Al, Cu, Sb and Pb were formed from lithogenic sources of weathering Quaternary units and atmospheric deposition. Most of the Cd, Sb, and Pb levels were derived from anthropogenic sources of industrial, agricultural, and fishing activities. The higher contribution of organic matter may be attributed to the mangrove roots and organic fertilizers; and played a key role in adsorbing, transferring and accumulating of elements.

Lossy Mode Resonance Generation on Sputtered Aluminum-Doped Zinc Oxide Thin Films Deposited on Multimode Optical Fiber Structures for Sensing Applications in the 1.55 µm Wavelength Range

In this work, we demonstrated lossy mode resonance (LMR) generation in optical fiber structures based on multimode fibers coated with aluminum-doped zinc oxide (AZO) films. AZO thin films were deposited by using radio frequency magnetron sputtering. In order to exhibit the usefulness of the LMR effect for sensing applications in optical fiber based systems, the deposition conditions of the AZO film coatings were set to obtain the second LMR order within the 1.55 µm wavelength range. An optical transmission configuration setup was used to investigate the LMR effect on fiber structures based on the use of no-core and cladding-removed multimode fibers coated with AZO films synthesized from metallic sputtering targets with different proportions of Zn:Al, 92:8% and 98:2%, at atomic concentrations. The optical and electrical/chemical features of the AZO films were characterized with UV–vis and XPS spectroscopy, respectively. The optical response of the proposed sensing configuration to refractive index (RI) variations was experimentally demonstrated. For the best approach, the sensitivity of wavelength displacement to RI variations on the liquid surrounding media was found to be 1214.7 nm/RIU.

Efficient phloem remobilization of Zn protects apple trees during the early stages of Zn deficiency.

Apple trees are extensively cultivated worldwide but are often affected by zinc (Zn) deficiency. Limited knowledge regarding Zn remobilization within fruit crops has hampered the development of efficient strategies for providing adequate amounts of Zn. In the present study, Zn distribution and remobilization were compared among apple trees cultivated under different Zn conditions. Without Zn application, plants showed visible symptoms of Zn deficiency at the shoot tips after 1 year but appeared to grow normally during the first 6 months (early stage of Zn deficiency). Compared with apple plants under sufficient Zn treatment, plants suffering from early-stage Zn deficiency showed preferential Zn distribution to young leaves and higher Zn levels in phloem, demonstrating that hidden Zn deficiency triggers a highly efficient remobilization of Zn in this species. The in vivo Zn-nicotianamine complex in phloem tissues, combined with the significant enhanced expression of MdNAS3 and MdYSL6, suggested a positive role for nicotianamine in the phloem remobilization of Zn. These results strongly suggest that a proportion of Zn in the old leaves of apple trees can be efficiently remobilized by phloem transport to the shoot tips, partially in the form of Zn-nicotianamine, thus protecting apple trees against the early stages of Zn deficiency.

Effects of Myo-inositol Hexakisphosphate on Zn(II) Sorption on γ-Alumina: A Mechanistic Study

Myo-inositol hexakisphosphate (IHP), a most common organic phosphorus in many soils, can strongly interact with aluminum (Al) oxides and influence the fate of metal ions. In this study, the effects of presorbed IHP on γ-Al2O3 (γ-alumina) surfaces on Zn(II) sorption were investigated in batch experiments using a combination of powder X-ray diffraction (XRD), in situ attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), 31P and 27Al solid-state nuclear magnetic resonance spectroscopies (NMR), and Zn K-edge extended X-ray absorption fine structure spectroscopy (EXAFS). The results of the batch experiments show that the presorption of IHP increases the sorption density of Zn(II) on γ-Al2O3 surfaces. The XRD data indicate that the presorption of IHP hinders the formation of Zn–Al layered double hydroxide (LDH) precipitates by raising the critical concentration of Zn(II) required to precipitate the complex. Solid-state NMR spectra further suggest that the chemical environment and speciation of IHP presorbed change, i.e., from inner-sphere surface complexes to ternary surface complexes and to zinc phytate precipitates (Zn-IHP) with the increase in Zn(II) concentration or pH. Linear combination fittings (LCFs) of the EXAFS spectra indicate that the proportion of Zn(II) in binary or ternary surface complexes decreases and that in Zn–Al LDH increases with increasing concentration of Zn(II) at pH 7. Furthermore, the order at which IHP and Zn are added in the reaction can influence the cosorption mechanism. At pH 7, more binary or ternary Zn surface complexes and Zn-IHP form, and less Zn–Al LDH precipitates form if Zn is added first. These results demonstrate that both the timing and concentration of IHP and divalent metals have sweeping influences on their solubility and speciation and these intricacies need to be taken into consideration toward predicting their fates in the environment.

Constructing and enhanced degradation rate of N-AZO/TiO2 core/shell nanocomposite by idiopathic molecular cladding process

The N - AZO / TiO 2 heterogeneous nanocomposite with core/shell structure revealed a better photocatalytic activity than the single N - AZO nanocrystals (NCs) even though it has a good photocatalytic effect. The recombination degree of photo-induced electrons and holes reduced significantly after molecular TiO 2 layer composited on the surface of N - AZO NCs. From the experiment of degrading rhodamine B solution (2 × 10-5 g/L) under solar light, the optimum photocatalytic efficiency was the N - AZO / TiO 2 composite prepared by idiopathic molecule-cladding (IMC) process and the best proportion of Zn / Ti was 2:1 in our research, which improved by 67% than pure N - AZO . Moreover, the N - AZO / TiO 2 composite prepared by IMC process achieved a molecular combination level between the two components, which not only can improve the immobility of composite structure, but also can make the photogenerated electrons and holes transport easier.

Geology, mineral chemistry and formation conditions of calc-silicate minerals of Astamal Fe-LREE distal skarn deposit, Eastern Azarbaijan Province, NW Iran

The Astamal Fe-LREE skarn deposit is the largest iron skarn in NW Iran. It is a unique case, as a distal skarn deposit which crops out approximately 600m from the associated Oligo-Miocene granodioritic pluton. This deposit formed in the south-southwest of the pluton where fractures and faults within the Upper Cretaceous volcano-sedimentary host rocks acted as conduits for the mineralizing fluids. The deposit contains three iron ore bodies: southern, northern and eastern. The main mineral assemblage within the ore zones is characterized by magnetite, pyrrhotite and pyrite, with lesser quantities of chalcopyrite, hematite, goethite and limonite. The skarn minerals predominantly comprise garnet, epidote, actinolite, calcite, quartz, clinopyroxene and chlorite (in order of abundance). Retrograde alteration is strongly developed in the skarn zone where most of the garnet has been pervasively altered to secondary minerals (e.g. epidote, calcite and quartz) both in the rims and the cores whereas the majority of the clinopyroxene has been replaced by a hydrous retrograde mineral assemblage (e.g. tremolite, actinolite and chlorite). Garnets with andradite–grossular compositions are the dominant mineral in the skarn zone, which are generally isotropic with a narrow compositional range along the growth lines (Adr94.3–64.5Grs21.9–2.7Alm11.1–0.2). These garnets are Fe-rich and have high Fe/(Fe+Al) ratios (between 0.96 and 0.78). Cu and Ni are enriched in the garnets. This suggests that these elements were enriched in the hydrothermal fluids from which the garnet precipitated. This is supported by the presence of chalcopyrite and Ni-bearing massive magnetite in the study area, which also suggests that Cu and Ni were enriched in the late stage ore-bearing hydrothermal fluids. Clinopyroxene with a hedenbergitic composition is generally homogenous and has particularly high Fe/Fe+Mg ratios (between 0.99 and 0.86) and is poor in TiO2, MnO and Cr2O3. High Zn concentrations were also detected in the clinopyroxenes (up to 1044ppm), despite an absence of significant Zn mineralization (such as sphalerite) in the district. Therefore, it is believed that the proportion of Zn in the hydrothermal fluids decreased significantly from the time of clinopyroxene formation to the period of the sulfide deposition phase. Allanite and LREE-bearing epidotes are the main LREE bearing minerals in this deposit. The epidote is also Fe-rich with high Fe/(Fe+Al) ratios (between 0.32 and 0.44). Due to a lack of replacement texture between both garnet and clinopyroxene and garnet and actinolite (which is formed by alteration of clinopyroxene), it is believed that these two minerals have grown simultaneously and are coexisting minerals. In the Astamal skarn, these minerals can be stable and coexisting at temperatures between 490 and 560°C and LogƒO2=−16 to −31.

Deposition of zinc–zinc phosphate composite coatings on aluminium by cathodic electrochemical treatment

The role of cathodic electrochemical treatment as an energy efficient and eco-friendly method to deposit zinc–zinc phosphate composite coatings on Al is addressed. The deposition of zinc–zinc phosphate composite coatings was carried out under galvanostatic conditions using an electrolyte solution containing 5g/l of ZnO and 12ml/l of o-phosphoric acid (85%), maintained at 27±1°C and two graphite disc anodes, placed on the two sides of the Al cathode. The applied current density (5 to 50mA/cm2), pH of the electrolyte (1.50, 2.30 and 3.00), treatment time (5 to 60min) and concentration of ZnO (1 to 5g/l) were used as the process variables. The methods of evaluation include, assessment of colour and uniformity by visual observations, adhesion by pull-off adhesion test, coating weight by a measure of gain in weight after deposition, morphological features by scanning electron microscopy, chemical composition by energy dispersive X-ray analysis and phase contents by X-ray diffraction studies. The corrosion resistance of the coatings, in 3.5% NaCl, was evaluated by potentiodynamic polarisation studies. The findings of this study reveal that the surface morphology, phase content and corrosion resistance of the composite coatings largely depend on the proportions of Zn and zinc phosphate in them. The cathodic electrochemical treatment method provides ample avenues to manipulate the volume fraction of Zn and zinc phosphate in the resultant composite coatings by a careful choice of the process parameters and hence, it is possible to deposit coatings on Al with varying degrees of corrosion protection.

Single crystalline In–Ga–Zn oxide films grown from c-axis aligned crystalline materials and their transistor characteristics

In this study, we analyzed the crystallinity of c-axis aligned crystalline In–Ga–Zn oxide (CAAC-IGZO) and single crystalline (sc) IGZO films. CAAC-IGZO films were formed on (111)-oriented yttria-stabilized-zirconia substrates by magnetron sputtering using a target. Sc-IGZO films were obtained by annealing CAAC-IGZO films at 1200 °C. The proportion of Zn in the composition changed during growth of the films, and as a result, sc-InGaO3(ZnO)3 films were obtained. By using CAAC-IGZO films as the starting material, sc-IGZO films were formed even without a ZnO layer. This is presumably because the CAAC-IGZO film originally exhibits c-axis orientation. In addition, the characteristics of transistors fabricated using sc-IGZO and CAAC-IGZO films were compared, and no significant difference in current drivability, i.e., field-effect mobility, was observed between the different transistors. In this sense, CAAC-IGZO films that require no high temperature annealing are favorable for industrialization.

Impacts of phosphorus and zinc levels on phosphorus and zinc nutrition and phytic acid concentration in wheat (Triticum aestivum L.)

Zinc (Zn) and phytic acid content in grain crops are directly related to their nutritional quality and therefore human health. To investigate the nutritional influences of phosphorus (P) and Zn levels on wheat (Triticum aestivum L.), plants were grown hydroponically to maturity in chelator-buffered solutions. Appropriate amounts of P, coupled with sufficient Zn, increased P and Zn concentrations in wheat grain. The Zn supply decreased both phytic acid and the molar ratios of phytic acid to Zn in wheat grain with respect to the Zn(0) treatment. Furthermore, proportions of Zn and P content in the grain relative to that of the whole plant were improved. With increasing P, the proportion of Zn and P content in the grain relative to the whole plant decreased. P and Zn acted antagonistically in roots. Excess P inhibited Zn uptake in roots, while Zn decreased the transfer of P from roots to shoots. For P that had been transported to the shoots, supplemental Zn facilitated its transfer to the grain. Excess P decreased the distribution of Zn in grain, while Zn enhanced the uptake of Zn and P in grain, The combined application of Zn fertilizer with the extensive use of P fertilizer can effectively increase the P and Zn concentration and Zn bioavailability of wheat grain, and hence Zn nutritional quality.

Zinc distribution and speciation in Arabidopsis halleri × Arabidopsis lyrata progenies presenting various zinc accumulation capacities

The purpose of this study was to investigate the relationship between the chemical form and localization of zinc (Zn) in plant leaves and their Zn accumulation capacity. An interspecific cross between Arabidopsis halleri sp. halleri and Arabidopsis lyrata sp. petrea segregating for Zn accumulation was used. Zinc (Zn) speciation and Zn distribution in the leaves of the parent plants and of selected F(1) and F(2) progenies were investigated by spectroscopic and microscopic techniques and chemical analyses. A correlation was observed between the proportion of Zn being in octahedral coordination complexed to organic acids and free in solution (Zn-OAs + Zn(aq)) and Zn content in the leaves. This pool varied between 40% and 80% of total leaf Zn depending on the plant studied. Elemental mapping of the leaves revealed different Zn partitioning between the veins and the leaf tissue. The vein : tissue fluorescence ratio was negatively correlated with Zn accumulation. The higher proportion of Zn-OAs + Zn(aq) and the depletion of the veins in the stronger accumulators are attributed to a higher xylem unloading and vacuolar sequestration in the leaf cells. Elemental distributions in the trichomes were also investigated, and results support the role of carboxyl and/or hydroxyl groups as major Zn ligands in these cells.

Uptake of zinc from zinc sulfate and zinc proteinate by ovine ruminal and omasal epithelia1,2

Uptake and transport of Zn from (65)Zn-labeled ZnSO(4) and Zn proteinate (ZnProt) by ruminal and omasal epithelia were examined by using a parabiotic chamber system. Uptake was measured during a 4-h incubation with 10, 20, or 200 microM Zn as ZnSO(4) or ZnProt in the mucosal buffer (pH 6.0, Krebs-Ringer phosphate). Zinc uptake and transport were also evaluated after simulated ruminal digestion. Buffered ruminal fluid contained a feed substrate and 10 or 200 microM added Zn as ZnSO(4) or ZnProt. In a preliminary experiment, uptake of Zn by omasal tissue was low; thus, the remaining experiments were conducted solely with ruminal epithelium. Incubations to determine the effect of time on Zn uptake from mucosal buffer containing 20 microM added Zn as ZnSO(4) or ZnProt resulted in increased (P < 0.01) Zn uptake as incubation time increased from 30 to 240 min. Zinc uptake was also greater (P = 0.02) from mucosal buffer containing ZnProt compared with ZnSO(4). Zinc uptake from incubations containing 10 or 200 microM was affected by source x concentration (P = 0.05) and concentration x time (P < 0.01) interactions. With 10 microM Zn, uptake was not influenced by Zn source, whereas when 200 microM Zn was added, Zn uptake from ZnProt was greater than from ZnSO(4). Increasing incubation time resulted in increased Zn uptake with 200 microM Zn in the mucosal buffer; however, with 10 microM Zn, uptake did not change after 30 min. After simulated ruminal fermentation, the proportion of Zn in a soluble form was influenced by a source x concentration interaction (P = 0.03). After 18 h of incubation, the proportion of Zn that was soluble was not different between ZnProt and ZnSO(4) in buffered ruminal fluid that contained 10 microM added Zn, but was greater for ZnProt compared with ZnSO(4) with 200 microM Zn in the incubation. Zinc uptake from the aqueous fractions of simulated ruminal digestions containing 200 microM added Zn was greater (P < 0.01) than from those containing 10 microM added Zn. Zinc transport, based on detection of (65)Zn in serosal buffer, did not occur in any of the experiments. The results of the current experiments suggest that absorption of Zn into the bloodstream does not occur from the ruminant foresto-mach; however, Zn uptake occurs in ruminal tissue and is greater from ZnProt than from ZnSO(4).