Zinc Compounds

Surface-modifi ed quantum dots (QDs) are extensively used as fl uorescent labels for sensing and biosensing events. [ 1 , 2 ] Fluorescence resonance energy transfer (FRET) or electron-transfer quenching of the QDs are two fundamental photophysical mechanisms to probe sensing processes at the surface of the QDs. [ 2 , 3 ] Indeed, these photophysical mechanisms were implemented to detect ions, [ 4 ] to follow pH changes, [ 5 ] and to detect molecular substrates, such as saccharides or neurotransmitters. [ 6 ] Similarly, QDs have been widely used for biosensing, and different luminescence sensors that follow the formation of antigen-antibody complexes, [ 7 ] DNA hybridization [ 8 , 9 ] and aptamer-substrate complexes [ 10 ] were reported. Also, QDs have been extensively used to follow biocatalytic transformations and to quantitatively probe the substrates of enzymes. [ 9 , 11 ] Here we wish to report on the use of chemically modifi ed CdSe/ZnS QDs as fl uorescent probes for the analysis of explosives, and specifi cally, the detection of trinitrotoluene (TNT) or trinitrotriazine (RDX). The QDs are functionalized with electron donating ligands that bind nitro-containing explosives, exhibiting electron acceptor properties, to the QDs surfaces, via supramolecular donor-acceptor interactions. The concentration of the explosive substrates at the QDs via the donor-acceptor complexes leads to the quenching of the luminescence of the QDs, thus allowing the quantitative analysis of the substrates. The sensitivities of the QDs sensors are controlled by the electron donating properties of the capping layer that modifi es the particles. The rapid and sensitive analysis of nitroaromatic explosives attracts substantial recent efforts, and different optical [ 12 ] or electrochemical [ 13 ] TNT or RDX sensors were reported. Other sensors for explosives include surface acoustic wave (SAW) systems, where piezoelectric crystal coated with absorbing materials such as carbowax [ 14 ] or cyclodextrin polymers, [ 15 ] were

Intrahippocampal injections of zinc chloride (5-10 nmol) caused a discrete lesion in the rat hippocampus, involving all neuronal perikarya. In addition to the necrosis, the lesion was also characterized by a decrease in staining of the neuropil, the presence of pyknotic neurons, and occasionally infarction. Pathological changes occurred within 8 h of an injection, and neuronal loss, as judged by the loss of Nissl staining, was complete within 24 h. On the other hand, the loss of acidophilic staining of the neurons was more gradual, as acid fuchsin staining was still present in neurons in the periphery of the damaged area 4 days later. In comparison with an excitotoxic lesion, glial infiltration into the damaged area was minimal, even up to 3 weeks later, suggesting that some glial cell toxicity also occurred.

A novel biocompatible chitosan passivated manganese doped zinc sulfide (Mn doped ZnS) nanophosphor has been synthesized through a simple aqueous precipitation reaction. Upon excitation with ultraviolet light, the quantum dots (QDs) emit an orange luminescence peaking at 590 nm, which is visible to the naked eye. These chitosan coated Mn doped ZnS QDs can have potential applications in bio-labeling, particularly in fluorescence-based imaging. One of the envisioned applications of these QDs is in improving the conventional, organic dye-reliant Fluorescence in situ Hybridization (FISH) technique, a widely used method for microbial detection. Here we demonstrate that the chitosan-capped Mn doped ZnS QDs are suitable for this purpose.

Background: Zinc carnosine (ZnC) is a health food product claimed to possess health-promoting and gastrointestinal supportive activity. Scientific evidence underlying these claims is, however, limited. Aim: To examine the effect of ZnC on various models of gut injury and repair, and in a clinical trial. Methods: In vitro studies used pro-migratory (wounded monolayer) and proliferation ([ 3 H]-thymidine incorporation) assays of human colonic (HT29), rat intestinal epithelial (RIE) and canine kidney (MDCK) epithelial cells. In vivo studies used a rat model of gastric damage (indomethacin/restraint) and a mouse model of small-intestinal (indomethacin) damage. Healthy volunteers (n = 10) undertook a randomised crossover trial comparing changes in gut permeability (lactulose:rhamnose ratios) before and after 5 days of indomethacin treatment (50 mg three times a day) with ZnC (37.5 mg twice daily) or placebo coadministration. Results: ZnC stimulated migration and proliferation of cells in a dose-dependent manner (maximum effects in both assays at 100 mmol/l using HT29 cells), causing an approximate threefold increase in migration and proliferation (both p,0.01). Oral ZnC decreased gastric (75% reduction at 5 mg/ml) and small-intestinal injury (50% reduction in villus shortening at 40 mg/ml; both p,0.01). In volunteers, indomethacin caused a threefold increase in gut permeability in the control arm; lactulose:rhamnose ratios were (mean (standard error of mean)) 0.35 (0.035) before indomethacin treatment and 0.88 (0.11) after 5 days of indomethacin treatment (p,0.01), whereas no significant increase in permeability was seen when ZnC was coadministered. Conclusion: ZnC, at concentrations likely to be found in the gut lumen, stabilises gut mucosa. Further studies are warranted.

Zinc (Zn) is essential for swine and poultry and native Zn concentrations in feedstuffs are too low to meet their Zn requirement. Dietary Zn bioavailability is affected by phytate, phytase and Zn supplemented in organic form is considered as more bioavailable than inorganic sources. A meta-analysis using GLM procedures was processed using broiler and piglet databases to investigate, within the physiological response of Zn, (1) the bioavailability of inorganic and organic Zn sources (Analysis I); (2) the bioavailability of native and inorganic Zn dependent from dietary phytates, vegetal and supplemental phytase activity (Analysis II). Analysis I: the bioavailability of organic Zn relative to inorganic Zn sources ranged, depending on the variable, from 85 to 117 never different from 100 (P> 0.05). The coefficients of determination of the regressions were 0.91 in broilers and above 0.89 in piglets. Analysis II: in broilers, bone Zn was explained by supplemental Zn (linear and quadra...

Composite polymer particles consisting of a solid poly(acrolein-co-styrene) core and a poly (N-vinylcaprolactam) (PVCL) polymer shell doped with CdSe/ZnS semiconductor quantum dots (QDs) were fabricated. The temperature response of the composite particles was observed as a decrease in their hydrodynamic diameter upon heating above the lower critical solution temperature of the thermosensitive PVCL polymer. Embedding QDs in the PVCL shell yields particles whose fluorescence is sensitive to temperature changes. This sensitivity was determined by the dependence of the QD fluorescence intensity on the distances between them in the PVCL shell, which reversibly change as a result of the temperature-driven conformational changes in the polymer. The QD-containing thermosensitive particles were assembled with protein molecules in such a way that they retained their thermosensitive properties, including the completely reversible temperature dependence of their fluorescence response. The composite particles developed can be used as local temperature sensors, as carriers for biomolecules, as well as in biosensing and various bioassays employing optical detection schemes.

Trichomonas vaginalis, Ecto-ATPase, Ecto-phosphatase, Galactose This work describes the ability of living Trichomonas vaginalis to hydrolyze extracellular ATP (164.0 ð 13.9 nmol Pi / h ¥ 10 7 cells). This ecto-enzyme was stimulated by ZnCl 2 , CaCl 2 and MgCl 2 , was insensitive to several ATPase and phosphatase inhibitors and was able to hydrolyze several nucleotides besides ATP. The activity was linear with cell density and with time for at least 60 min. The optimum pH for the T. vaginalis ecto-ATPase lies in the alkaline range. d-galactose, known to be involved in adhesion of T. vaginalis to host cells, stimulated this enzyme by more than 90%. A comparison between two strains of T. vaginalis showed that the ecto-ATPase activity of a fresh isolate was twice as much as that of a strain axenically maintained in culture, through daily passages, for several years. The results suggest a possible role for this ecto-ATPase in adhesion of T. vaginalis to host cells and in its pathogenicity.

Fluorescence molecular imaging is rapidly increasing its popularity in image guided surgery applications. To help develop its full surgical potential it remains a challenge to generate dual-emissive imaging agents that allow for combined visible assessment and sensitive camera based imaging. To this end, we now describe multispectral InP/ZnS quantum dots (QDs) that exhibit a bright visible green/yellow exciton emission combined with a long-lived far red defect emission. The intensity of the latter emission was enhanced by X-ray irradiation and allows for: 1) inverted QD density dependent defect emission intensity, showing improved efficacies at lower QD densities, and 2) detection without direct illumination and interference from autofluorescence.

This document is the author's final manuscript version of the journal article, incorporating any revisions agreed during the peer review process. There may be differences between this and the publisher's version. You are advised to consult the publisher's version if you wish to cite from this article.

The first stages of the synthesis of ZnO nanoparticles by forced hydrolysis of ZnCl2 with NaOH and water in ethanol have been investigated using UV-Vis spectrophotometry. At sufficiently low water concentrations, focusing of the nanoparticle size distribution was observed during the nucleation and growth phase, followed by a defocusing phase when coarsening becomes significant. During nucleation and growth, only the smaller particles grow while the larger particles have an essentially zero growth rate, indicating that the growth rate decreases rapidly with particle size. As the average particle size remains nearly constant in this regime, the absorbance increase with time can be used to determine the nucleation rate. The nucleation rate was found to depend on both the water concentration and the reactant concentrations. The results are discussed in terms of a mechanism where water determines the precursor formation kinetics thus controlling the nucleation rate.The first stages of the synthesis of ZnO nanoparticles by forced hydrolysis of ZnCl2 with NaOH and water in ethanol have been investigated using UV-Vis spectrophotometry. At sufficiently low water concentrations, focusing of the nanoparticle size distribution was observed during the nucleation and growth phase, followed by a defocusing phase when coarsening becomes significant. During nucleation and growth, only the smaller particles grow while the larger particles have an essentially zero growth rate, indicating that the growth rate decreases rapidly with particle size. As the average particle size remains nearly constant in this regime, the absorbance increase with time can be used to determine the nucleation rate. The nucleation rate was found to depend on both the water concentration and the reactant concentrations. The results are discussed in terms of a mechanism where water determines the precursor formation kinetics thus controlling the nucleation rate. Electronic supplementary information (ESI) available: Figures illustrating the time dependence of (a) the absorbance maximum and (b) λ1/2 for different [NaOH]/[ZnCl2] ratios at a fixed water concentration of 100 mM and 1 mM ZnCl. See DOI: 10.1039/c0nr00439a

The reaction of zinc chloride, acetate, or perchlorate with two bis(thioscmicarbazones) of 2,6diacetylpyridine [H2daptsc = 2,6-diacetylpyridine bis(thiosemicarbazone) and H2dapipt = 2,6diacetylpyridine bis(hydrazinopyruvoylthiosemicarbazone)] leads to the formation of four novel complexes that have been characterized by spectroscopic studies (NMR, IR) and biological properties. The crystal structures of the two compounds--[Zn(daptsc)]2-2DMF (1) and [Zn(H2dapipt)(OH2)2](CIO4)2.3H20 (2)--also have been determined by x-ray methods from diffractometer data, Compound (1) is dimeric and the two zinc atoms have a distorted octahedral coordination. The ligand is deprotonated. In compound (2), the coordination geometry about zinc is pentagonal--bipyramidal and the ligand is in the neutral form. The molecular structure of (2) consists of cations [Zn(H2dapipt)(OH2)2] 2+, C104 disordered anions, and three water molecules of solvation.

A method is presented to prepare nanocrystalline α-Zn2SiO4 with the smallest crystal size reported so far for this system. Our approach combines the advantages of organometallic single-source precursor routes with aerosol processing techniques. The chemical design of the precursor enables the preferential formation of pure zinc silicates. Since gas-phase synthesis reduces intermolecular processes, and keeps the particles small, zinc silicate was synthesized from the volatile organometallic precursor [{MeZnOSiMe3}4], possessing a Zn-methyl- and O-silyl-substituted Zn4O4-heterocubane framework (cubane), under oxidizing conditions, using the chemical vapor synthesis (CVS) method. The products obtained under different process conditions and their structural evolution after sintering were investigated by using various analytical techniques (powder X-ray diffraction, transmission electron microscopy, EDX analysis, solid-state NMR, IR, Raman, and UV/Vis spectroscopy). The deposited aerosol obtained first (processing temperature 750 °C) was amorphous, and contained agglomerates with primary particles of 12 nm in size. These primary particles can be described by a [Zn-O-Si] phase without long-range order. The deposit obtained at 900 °C contained particles with embedded nanocrystallites (3–5 nm) of β-Zn2SiO4, Zn1.7SiO4, and ZnO in an amorphous matrix. On further ageing, the as-deposited particles obtained at 900 °C form α-Zn2SiO4 imbedded in amorphous SiO2. The crystallite sizes and primary particle sizes in the formed α-Zn2SiO4 were found to be below ∼50 nm and mainly spherical in morphology. A gas-phase mechanism for the particle formation is proposed. In addition, the solid-state reactions of the same precursor were studied in detail to investigate the fundamental differences between a gas-phase and a solid-state synthesis route.

The development of metal-containing pharmaceuticals as insulin-mimetics has been the object of recent worldwide research. We have examined a series of zinc(II) and molybdenum(VI) complexes with model O,S-donor ligands (thiomaltol and 1,2-dimethyl-3-hydroxypyridine-4-thione (DMHTP)) and the corresponding O,O-analogues (maltol and DMHP) for their insulin-mimetic activity. Aimed at getting structure-activity relationships, some physical-chemical properties were also studied, such as metal-complex formation, speciation at different pH conditions and ligand lipophilicity. The Zn-complexes exhibit considerably higher insulin-mimetic activity than the corresponding Mo-analogues. Particularly, the bis(thiomaltolato)zinc(II) complex reveals a very high activity, ascribed to the effect of the thione p character and to the soft nature of the sulfur donor atom enhancing the Zn(II)-ligand affinity and the ligand/complex lipophilicity, two determinant parameters for delivering the metal-drug into the cells. Hence, these preliminary studies indicate that the Zn(thiomaltol) 2 complex can be considered a potential drug candidate for treatment of diabetes mellitus, upon in vivo evaluations.

The clinical efficacy of current antidepressant therapies is unsatisfactory; antidepressants induce a variety of unwanted effects, and, moreover, their therapeutic mechanism is not clearly understood. Thus, a search for better and safer agents is continuously in progress. Recently, studies have demonstrated that zinc and magnesium possess antidepressant properties. Zinc and magnesium exhibit antidepressant-like activity in a variety of tests and models in laboratory animals. They are active in forced swim and tail suspension tests in mice and rats, and, furthermore, they enhance the activity of conventional antidepressants (e.g., imipramine and citalopram). Zinc demonstrates activity in the olfactory bulbectomy, chronic mild and chronic unpredictable stress models in rats, while magnesium is active in stress-induced depression-like behavior in mice. Clinical studies demonstrate that the efficacy of pharmacotherapy is enhanced by supplementation with zinc and magnesium. The antidepre...

Introduction – Zinc is an essential micronutrient for plants, animals and humans; on the other hand, it is a pollutant. Zinc is released into the aquatic environment through several industrial activities, such as mining, metal coating, battery production and also ceramic, wood, fabric, drug, sun blocks and deodorant industry. Human exposure to these heavy metals at significant levels can cause serious health effects. Accumulated zinc at human body can lead to health problems as " metal-fume fever " , nausea, diarrhoea, depression, lethargy, and neurological signs, such asseizures and ataxia [1–3]. Consequently, removal of zinc from wastewater is necessary to ensure adequately treated effluent quality for various uses. The permissible ion concentration level in drinking water as set by World Health Organization (WHO) is 5 mg/L for zinc. In this study, perlite and chitosan dispersed perlite were used as the adsorbent. Perlite is a naturally occurring dense glassy volcanic rock which includes mainly fused sodium potassium aluminium silicate (greater than 70%) and 3–5% water. Silanol groups can form on the perlite surface providing various adsorption properties. Chitosan, poly(D-glucosamine), is obtained by deacetylation of chitin. Chitosan is a natural biopolymer, hydrophilic, and has the ability to form complexes with metals. It is also a non-toxic, biodegradable and biocompatible material. It contains primary amino groups, which are useful for chemical modifications [4]. In this study, batch studies were performed to investigate the effects of various experimental parameters on zinc removal such as pH, initial zinc concentration, contact time, adsorbent ratio. Equilibrium isotherms of batch system were also analyzed by Langmuir, Freundlich, Temkin and Dubinin-Redushkevich isotherm models. 2. Experimental-In this study, chitosan was dispersed on perlite to enhance the accessibility of OH and amine groups for adsorption of zinc ions. Chitosan coated perlite was prepared as spherical beads. Batch studies were performed to investigate the effects of various experimental parameters on zinc removal. From 0.5g/L to 12.5 g/L perlit and chitosan dispersed perlite were used as adsorbent to find the optimum zinc removal. Contact time experiments were run between 3-72 h. pH experiments were run between pH 4-10. To obtain the adsorption isotherms, initial zinc solution concentration was changed between 0.005-0.04 M. Zinc concentrations were measured by spectrophotometer (Jenway 6305 UV Spectrophotometer) according to zincon method. 3. Results and Discussion – Adsorption capacity of perlite was found %54 according to zincon method. 72 h end-over-end shaking was enough to reach the adsorption equilibrium. The maximum zinc adsorption was occurred at pH 7.5-8.0. Whereas with chitosan dispersed perlite, zinc was adsorbed at the range of %78 and zinc adsorption with chitosan dispersed perlite was reached maximum at pH =5.5-6. Zinc adsorption isotherm was obtained by changing the initial zinc concentration. Temkin isotherm model was fitted well with experimental parameters for both of the adsorbents. Maximum zinc uptake was found 1197 mg/L and 1941 mg/L for perlite and chitosan dispersed perlite, respectively. 4. Conclusions – Maximum zinc removal was observed in the presence of chitosan dispersed perlite. Temkin isotherm model described well zinc removal on the both perlite and chitosan dispersed perlite single layer zinc adsorption. Chitosan coated perlite was showed higher zinc adsorption compared with perlite.

ZnO nanowires (NWs) with a ZnS coating are synthesized in order to modify the surface without changing the diameter of the NWs. They have the wurtzite ZnO at the core and a cubic ZnS at the outer layer. The NWs show a sharp ultraviolet and a broad visible emission of the photoluminescence spectra. Surface modification has led to a change in the position of the maxima of the visible emission in ZnO-ZnS NWs. The photocarrier relaxation under steady UV illumination occurs in ZnO NW arrays but is absent in ZnO-ZnS NW arrays. The dark current value for both type of NWs are similar, whereas the photocurrent value is much higher in the surface-modified NWs. Higher photocurrent value indicates a transport of the photogenerated carriers from the ZnS layer to ZnO during UV illumination. The carrier transport mechanism is proposed through a model.

Background. Cosmetic products are not tested with the same rigour as medical treatments, but recent high-quality studies have shown significant reductions in changes of skin ageing with use of cosmetic antiageing products. Aim. To test whether a cosmetic 'anti-spot' two-step treatment containing a complex of seaweed-derived oligosaccharide and zinc would produce a significant improvement in mild acne. Methods. A double-blind, vehicle-controlled trial of this treatment was performed for 8 weeks on 60 age-matched participants with mild acne. They were divided into two groups: 30 participants were treated with vehicle control and 30 with the active treatment containing a seaweed-derived oligosaccharide complexed with 0.1% zinc pyrrolidone. Results. After 8 weeks, both groups had a reduction in comedones, papules and pustules, and this was significantly greater in the active than control group at 2, 4 and 8 weeks.

It is generally accepted that the amino acid reagent consisting of 1,2-indanedione and a catalytic amount of zinc chloride, referred to as IND-Zn, is the single best method for the detection of latent fingermarks on paper substrates and that ninhydrin is of limited value when used in sequence after this reagent. However, recent research has suggested that the sequence 1,8-diazafluoren-9-one (DFO) followed by ninhydrin may actually produce a greater number of fingermarks than IND-Zn on its own or IND-Zn followed by ninhydrin.

Observation by transmission electron microscopy, coupled with morphometric analysis and estimation procedure, revealed unique ultrastructural features in 25.94% of noradrenaline (NA)-containing granules and 16.85% of adrenaline (A)-containing granules in the rat adrenal medulla. These consisted of evaginations of the granule limiting membrane to form budding structures having different morphology and extension. In 14.8% of NA granules and 12.0% of A granules, outpouches were relatively short, looked like small blebs emerging from the granule surface and generally contained electron-dense material. A proportion of 11.2% of NA granules and 4.9% of A granules revealed the most striking ultrastructural features. These secretory organelles presented thin, elongated, tail-like or stemlike appendages, which were variably filled by chromaffin substance and terminated with spherical expansions of different electron density. A cohort of vesicles of variable size (30-150 nm in diameter) and content was found either close to them or in the intergranular cytosol. Examination of adrenal medullary cells fixed by zinc iodide-osmium tetroxide (ZIO) revealed fine electron dense precipitates in chromaffin granules, budding structures as well as cytoplasmic vesicles. These data indicate that a common constituent is revealed by the ZIO histochemical reaction in chromaffin cells. As catecholic compounds are the main tissue targets of ZIO complexes, catecholamines are good candidates to be responsible for the observed ZIO reactivity. This study adds further to the hypothesis that release of secretory material from chromaffin granules may be accomplished by a vesiclular transport mechanism typical of piecemeal degranulation.

The wet mechanochemical procedure for the capping of the CdS and CdS/ZnS quantum dot nanocrystals is reported. l-cysteine and polyvinylpyrrolidone (PVP) were used as capping agents. When using l-cysteine, the dissolution of cadmium(II) was almost none for CdS/ZnS nanocrystals. Moreover, prepared CdS- and CdS/ZnS-cysteine nanosuspensions exhibited unimodal particle size distributions with very good stability, which was further supported by the zeta potential measurements. The Fourier-transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy showed the successful embedment of cysteine into the structure of the nanocrystals. Additionally, the optical properties were examined, and the results showed that the cysteine nanosuspension has promising fluorescence properties. On the other hand, PVP was not determined to be a very suitable capping agent for the present system. In this case, the release of cadmium(II) was higher in comparison to the l-cysteine capped samples. The nanosuspensions were successfully used for in vitro studies on selected cancer cell lines. Using fluorescence microscopy, it was evidenced that the nanocrystals enter the cell and that they can serve as imaging agents in biomedical applications.

The use of plant extract in the synthesis of nanostructured materials can be a cost effective and eco-friendly approach. In this paper we report the biosynthesis of zinc oxide nanoparticles using Citrus aurantifolia extracts. Spherical zinc oxide nanoparticles were produced using different concentration of zinc acetate which was used as the zinc source. FESEM imaging showed the formation of nanoparticles in the size range of 50-200 nm. XRD analysis revealed wurtzite hexagonal ZnO with preferential orientation at (1 0 0) reflection plane. The room temperature PL spectroscopy showed little variation for samples deposited with different zinc acetate concentration. Peak due to V o +, Vo, hole trapped at Vo, O i and hydroxyl groups were observed with slight variation in peak position. The synthesis of zinc oxide nanoparticles using the citrus extracts were found to be comparable to those obtained from conventional reduction methods using hexamethylenetetramine or cetyltrimethylammonium bromide and can be an excellent alternative for the synthesis of ZnO nanoparticles using biomaterials. © 2012 Elsevier Ltd and Techna Group S.r.l.

With controlled nanometre-sized pores and surface areas of thousands of square metres per gram, metal-organic frameworks (MOFs) may have an integral role in future catalysis, filtration and sensing applications. In general, for MOF-based device fabrication, well-organized or patterned MOF growth is required, and thus conventional synthetic routes are not suitable. Moreover, to expand their applicability, the introduction of additional functionality into MOFs is desirable. Here, we explore the use of nanostructured poly-hydrate zinc phosphate (α-hopeite) microparticles as nucleation seeds for MOFs that simultaneously address all these issues. Affording spatial control of nucleation and significantly accelerating MOF growth, these α-hopeite microparticles are found to act as nucleation agents both in solution and on solid surfaces. In addition, the introduction of functional nanoparticles (metallic, semiconducting, polymeric) into these nucleating seeds translates directly to the fabrication of functional MOFs suitable for molecular size-selective applications.

Utilization of agrowaste materials for the production of activated carbon, as an excellent adsorbent with large surface area, is well established industrially, for dephenolation of wastewater. In the present work, dried pods of Prosopis cineraria-a novel and low-cost agrowaste material-were used to prepare activated carbons by zinc chloride activation. Batch adsorption experiments were carried out to study the effects of various physicochemical parameters such as initial phenol concentration, adsorbent dose, initial solution pH, and temperature. Pseudo-first-order second-order and diffusion kinetic models were used to identify the possible mechanisms of such adsorption process. The Langmuir and Freundlich equations were used to analyze the adsorption equilibrium. Maximum removal efficiency of 86 % was obtained with 25 mgL −1 of initial phenol concentration. The favorable pH for maximum phenol adsorption was 4.0. Freundlich equation represented the adsorption equilibrium data more ideally than the Langmuir. The maximum adsorption capacity obtained was 78.32 mg g −1 at a temperature of 30°C and 25 mgL −1 initial phenol concentration. The adsorption was spontaneous and endothermic. The pseudo-second-order model, an indication of chemisorption mechanism, fitted the experimental data better than the pseudo-first-order Lagergren model. Regeneration of spent activated carbon was carried out using Pseudomonas putida MTCC 2252 as the phenol-degrading microorganism. Maximum regeneration up to 57.5 % was recorded, when loaded phenol concentration was 25 mgL −1 . The data obtained in this study would be useful in designing and fabricating an efficient treatment plant for phenol-rich effluents.

Spinels form an interesting class of compounds, finding applications in metal-ion batteries and as catalysts for metal−air batteries and fuel cells. Here, we report a fast, template-free solution combustion method to synthesize nanoscale zinc spinels for applications as cathodes in low-cost aqueous zinc-ion batteries and oxygen reduction reaction (ORR) catalysts. It leads to the formation of phase-pure spinels with near spherical nanoscale morphology. Three spinelsZnCo 2 O 4 (ZCO), ZnMn 2 O 4 (ZMO), and ZnMnCoO 4 (ZMCO)were investigated. ZMO and, for the first time, ZMCO were observed to show reversible Zn (de)insertion involving Mn 4+ /Mn 3+ redox couple with a first discharge capacity of 109.4 mAh/g (i.e., >99% of theoretical capacity). Further, these Zn-based spinels showed appreciable oxygen reduction reaction (ORR) electrocatalytic activity. The ORR activity in alkaline solution was characterized by cyclic voltammetry (CV) and linear sweep voltammetry (LSV) using a rotating disk electrode (RDE) and was observed to be comparable to Pt/C with similar chronoamperometric stability. This enhanced ORR activity can be rooted to the optimal tuning of Co 3+ −O bond strength because of the presence of Mn 3+. This work presents a robust synthesis route to prepare ZnMnCoO 4 spinel acting as an economic cathode material for large-scale Zn-ion batteries for grid storage applications as well as an efficient and stable alternate ORR catalyst in alkaline solution.

Fluoride toothpastes in conjunction with tooth brushing are used to clean teeth, control plaque build-up and for anti-caries benefits. Toothpastes are designed with attractive flavours and appearances to encourage regular prolonged use to maximise these benefits. The incorporation of additional ingredients into toothpaste is a convenient way to provide supplementary protection that fits into people's everyday oral care routine. Such ingredients should not compromise the primary health benefits of toothpaste nor discourage its use. o-Cymen-5-ol and zinc chloride have been incorporated into a sodium fluoride (NaF) ⁄ silica toothpaste at 0.1%w ⁄ w and 0.6%w ⁄ w respectively to provide additional benefits. These include improved gingival health maintenance, in terms of the reduction of plaque, gingival index and bleeding, and an immediate and long lasting reduction in volatile sulfur compounds (VSCs) measured on breath. These benefits can be attributed to the antimicrobial and neutralisation actions of the toothpaste. The use of established fluoride models demonstrated no compromise in NaF bioavailability. The toothpaste was formulated without compromising product aesthetics. The combination of o-cymen-5-ol and zinc chloride in toothpaste gave superior maintenance of gingival health and reduction in malodour related VSCs without compromising the primary health benefits of the toothpaste or diminishing attributes preferred for the product's use.

In this study the effects of initial concentration of Fe(II) and Fe(III) ions as well as initial pH on the bioleaching of a low-grade sphalerite ore in a leaching column over a period of 120 days with and without bacteria were investigated. Four different modifications of medium were used as column feed solutions to investigate the effects of initial concentration of Fe(II) and Fe(III) ions on zinc extraction. The experiments were carried out using a bench-scale, column leaching reactor, which was inoculated with mesophilic iron oxidizing bacteria, Acidithiobacillus ferrooxidans, initially isolated from the Sarcheshmeh chalcopyrite concentrate (Kerman, Iran). The effluent solutions were periodically analyzed for Zn, total Fe, Fe(II) and Fe(III) concentrations as well as pH values. Bacterial population was measured in the solution (free cells). Maximum zinc recovery in the column was achieved about 76% using medium free of initial ferrous ion and 11.4 g/L of ferric ion (medium 2) at pH 1.5. The extent of leaching of sphalerite ore with bacteria was significantly higher than that without bacteria (control) in the presence of ferrous ions. Fe(III) had a strong influence in zinc extraction, and did not adversely affect the growth of the bacteria population.

The development of metal-containing pharmaceuticals as insulin-mimetics has been the object of recent worldwide research. We have examined a series of zinc(II) and molybdenum(VI) complexes with model O,S-donor ligands (thiomaltol and 1,2-dimethyl-3-hydroxypyridine-4-thione (DMHTP)) and the corresponding O,O-analogues (maltol and DMHP) for their insulin-mimetic activity. Aimed at getting structure-activity relationships, some physical-chemical properties were also studied, such as metal-complex formation, speciation at different pH conditions and ligand lipophilicity. The Zn-complexes exhibit considerably higher insulin-mimetic activity than the corresponding Mo-analogues. Particularly, the bis(thiomaltolato)zinc(II) complex reveals a very high activity, ascribed to the effect of the thione p character and to the soft nature of the sulfur donor atom enhancing the Zn(II)-ligand affinity and the ligand/complex lipophilicity, two determinant parameters for delivering the metal-drug into the cells. Hence, these preliminary studies indicate that the Zn(thiomaltol) 2 complex can be considered a potential drug candidate for treatment of diabetes mellitus, upon in vivo evaluations.

The rising trend of antibiotic resistance in acne and rosacea across the world has prompted scientists to look for options to circumvent this trend. 1 Though isotretinoin is a good alternative, we feel that zinc, if used with the proper base, may be of help both in inflammatory acne and to prevent resistance in patients with acne. 2,3 The study by Bamford et al. 4 where the use of oral zinc sulfate was not associated with significant improvement in rosacea severity over a 90-day trial is contrary to existing literature, though this can be explained by the difference in population race/ethnicity and dietary conditions. We feel that the issue of the effects of zinc in acne vulgaris and rosacea should focus on the preparation of zinc used. The available preparations include zinc acetate, zinc octoate, zinc citrate, zinc picolinate, zinc ascorbate, zinc gluconate, and methionine-bound zinc. 1,3,5 The newer zinc formulations are better dissolved in the stomach and more completely absorbed, making it possible to administer lower doses of zinc, with better gastrointestinal acceptability. 3,5 Our premise is that the bioavailability of zinc in oral preparations is crucial for its response in acne and/or rosacea, and methionine-bound zinc could have Figure 2 A depiction of the varied modes of action of zinc in acne, note the pronounced anti-inflammatory effect. ICAM, intercellular adhesion molecules; IL, interleukin; LFA, lymphocyte function-associated antigen; NK, natural killer (cells); PMN, polymorphonuclear leukocyte; TNF, tumor necrosis factor

In the primary structure of protein kinase C, the presence of a putative metal-binding site has been suggested (Parker, P. J., Coussens, L., Totty, N., Rhee, L., Young, S., Chen, E., Stabel, S., Waterfield, M. D., and Ullrich, A. (1986) Science 233,853-859). In the present report, we demonstrate that the most abundant intracellular heavy metal, zinc, can increase the activity of cytosolic protein kinase C. Zinc reversibly binds the enzyme to plasma membranes, and it may contribute to the calcium-induced binding as well. The intracellular heavy metal chelator N,N,N',N'-tetrakis(2pyridylmethyl) ethylenediamine prevents the phorbol ester-and antigen-induced translocation of protein kinase C. This effect can be totally reversed by the concomitant addition of Zn2+, while Fez+ and Mn2+ are only partially counteractive. Our results suggest that zinc can activate protein kinase C and contributes to its binding to plasma membranes in T lymphocytes induced by Ca", phorbol ester, or antigen.

Specialty chemicals based on renewable resources are desirable commodities due to their ecofriendly nature and "green" product characteristics. These chemicals can demonstrate physical and chemical properties comparable to those of conventional petroleum-based products. Suitably functionalized amines in the triacylglycerol structure can function as an antioxidant, as well as an antiwear/antifriction agent. In addition, the amphiphilic nature of seed oils makes them an excellent candidate as base fluid. The reaction of amine and epoxidized seed oils in the presence of a catalyst almost always leads to different intra/intermolecular cross-linked products. In most cases, the triacylglycerol structure is lost due to disruption of the ester linkage. Currently, there is no reported literature describing the aminolysis of vegetable oil without cross-linking. Here the epoxy group of the epoxidized soybean oil has been selectively reacted with amines to give amine-functionalized soybean oil. The optimization procedure involved various amines and catalysts for maximum aminolysis, without cross-linking and disruption of the ester linkage. Diethylamine and ZnCl 2 were found to be the best. NMR, IR, and nitrogen analysis were used to characterize the products.

The main theme of this chapter concerns the precise biochemical mechanisms involved in stages up to, and including, gastrointestinal absorption of vitamins and certain selected minerals. Essential data regarding sequential events, immediately following absorption of these micronutrients, are also included. There is reference to water-soluble vitamins that are, in general, either coenzymes in various metabolic reactions or carriers of certain biochemical groupings. In contrast, fat-soluble vitamins frequently function as integral components of cell membranes; they, too, receive ample attention. It is appropriate, nevertheless, to recognize that some minerals required in very small amounts are closely allied biochemically with particular vitamins; these specific associations are apportioned emphasis at relevant places in the text. Although predominant discussion centres on the physiological state, clinical reference is necessarily made to gastrointestinal disorders in which imbalance of vitamins and minerals consequently results in an additional detrimental impact on health. the vitamins, together with a select group of inorganic elements and the factors that, in turn, modify them.

In this study, utilization of a solid waste as raw material for activated carbon production was investigated. For this purpose, activated carbons were produced from chromium and vegetable tanned leather shaving wastes by physical and chemical activation methods. A detailed analysis of the surface properties of the activated carbons including acidity, total surface area, extent of microporosity and mesoporosity was presented. The activated carbon produced from vegetable tanned leather shaving waste produced has a higher surface area and micropore volume than the activated carbon produced from chromium tanned leather shaving waste. The potential application of activated carbons obtained from vegetable tanned shavings as adsorbent for removal of water pollutants have been checked for phenol, methylene blue, and Cr(VI). Adsorption capacities of activated carbons were found to be comparable to that of activated carbons derived from biomass.

We define ''dual fingerprint reagents'' as chemical formulations that produce with latent fingerprints in one stage impressions that are both colored and fluorescent. Solutions containing ninhydrin and group IIb metal salts appear to be true dual reagents. Application of these formulations to latent fingerprints on paper is as efficient as the two-step process beginning with ninhydrin and followed by treatment with metal salt. In the color mode, fingerprint detectability with the two ninhydrin-metal salt reagents (one with zinc chloride and the other with cadmium chloride) is comparable with that of ninhydrin itself, in spite of the difference in color. The sensitivity is significantly higher in the fluorescence mode. To view the latent impressions the exhibits are treated with ninhydrin-metal salt reagents and observed under white light illumination and under fluorescence conditions. Cooling to liquid nitrogen temperature enhances the fluorescence considerably. In the shorter wavelength domain, ninhydrin-metal salt reagents exhibit higher sensitivity than the recently reported dual reagent, genipin. The latter is advantageous, however, in the longer wavelength domain, on paper items with strong self-fluorescence, such as brown wrapping paper or paper printed with fluorescent ink. Upon reduction of the ninhydrin concentration 10-fold, ninhydrin-metal salt formulations become purely fluorogenic reagents; no color is noticed but the fluorescence is as intense as with concentrated solutions. Working at lower concentrations is an advantage from ecological and economical viewpoints.

The role of Thiobacillus ferrooxidans in bacterial leaching of mineral sulfides is controversial. Much of the controversy is due to the fact that the solution conditions, especially the concentrations of ferric and ferrous ions, change during experiments. The role of the bacteria would be more easily discernible if the concentrations of ferric and ferrous ions were maintained at set values throughout the experimental period. In this paper we report results obtained by using the constant redox potential apparatus described previously (P. I. Harvey and F. K. Crundwell, Appl. Environ. Microbiol. 63:2586-2592, 1997). This apparatus is designed to control the redox potential in the leaching compartment of an electrolytic cell by reduction or oxidation of dissolved iron. By controlling the redox potential the apparatus maintains the concentrations of ferrous and ferric ions at their initial values. Experiments were conducted in the presence of T. ferrooxidans and under sterile conditions....

Studies on the Merrill-Crowe process as applied to silver recovery have shown that one half of the used zinc powder is wasted in water reduction at high cyanide concentrations, while the other half reduces silver ions from the cyanide solution. However, the cementation mechanisms as an electrochemical process taking place on the zinc surface do not explain the split of the electric current resulting from the anodic dissolution of zinc into two equal values. This study demonstrates that the mechanism for silver precipitation at high and low cyanide concentrations differs considerably. At low cyanide concentrations cementation is essentially an electrochemically-controlled process following a shrinking-core behavior. At high cyanide concentrations, the process seems not to be electrochemically controlled. The areas for zinc dissolution and silver deposition are not connected by an electrical-conducting medium and reduction of silver-cyano complex ions takes place by hydrogen adsorbed onto silver growing outward from the cementing zinc particles. The results are based on scanning electron microscopy of solids recovered from cementations in stirred reactors and in situ observations by optical microscopy of the cementation process on the edge of thin zinc disks in cyanide solutions.

Interest in taking advantage of the unique spectral properties of semiconductor quantum dots (QDs) has driven their widespread use in biological applications such as in vitro cellular labeling/imaging and sensing. Despite their demonstrated utility, concerns over the potential toxic effects of QD core materials on cellular proliferation and homeostasis have persisted, leaving in question the suitability of QDs as alternatives for more traditional fluorescent materials (e.g., organic dyes, fluorescent proteins) for in vitro cellular applications. Surprisingly, direct comparative studies examining the cytotoxic potential of QDs versus these more traditional cellular labeling fluorophores remain limited. Here, using CdSe/ZnS (core/shell) QDs as a prototypical assay material, we present a comprehensive study in which we characterize the influence of QD dose (concentration and incubation time), QD surface capping ligand and delivery modality (peptide or cationic amphiphile transfection r...