STUDY ON THERMAL DECOMPOSITION KINETICS OF URUSHIOL METAL CHELATE POLYMERS

The thermal decomposition kinetics of urushiol-Cu, urushiol-Nd and urushiol-Ti chelatepolymers has been studied by non-isothermal thermogravimetry. The results suggest that thethermal decomposition kinetics of three chelate polymers are all of first order. Their averageactivation energy values of the thermal decomposition calculated by Ozawa-(I) method are 110,79, 136. 98 and 163. 64 kJ mol^(-1) respectively, which increase linearly with the metal valence of themetal chelate polymers

THE MECHANISM OF SURFACE METALLIZATION OF POLYVINYL ALCOHOL COMPLEX METAL CHELATE FILMS

A novel method for preparing metalllzed film has been studied.The reduction process and properties of the poly(vinyl alcohol)(PVA)were probed by several analytic means.According to the etudies,a mechanism for the polymer surface reduction metallization was proposed and proved.

pH-metric and thermodynamic studies of rare earth metal chelates

Proton ligand stability constants of hydroxybenzoic acid containing nitro group （2-Hydroxy-4-nitrobenzoic acid and 3-Hydroxy-4- nitrobenzoic acid） were determined through lrving-Rossoti pH titration technique. The stability constants of rare earth metal chelates containing 2-Hydroxy-4-nitrobenzoic acid and 3-Hydroxy-4-nitrobenzoic acid as ligands were studied in aqueous medium at different ionic strength （p=0.01, 0.05 and 0.1 mol/L） and temperatures （298, 308 and 318± 0.1 K）. The values of stability constant were evaluated through different computational methods like successive approximation, least square treatment, correction term method, and convergence method. The observed value of thermodynamic parameters （△G°, △H° and △S°） favors the complex formation between metal and ligands. The order of stabifity constant was found to be Pr（III）〈Nd（III）〈Sm（III）〈Tb（III）〈Ho（III）〈Er（III） as reported by Stagg and Powell.

Synthesis and Characterization of Some Transition Metal Chelates of 5-(1-Hydroxy-6-Naphthylazo-3-Sodium Sulphonate) Thiobarbituric (L_1) and Barbituric (L_2) Acids

Some transition metal chelates of two ligands L1 and L2 were prepared and characterized by elemental analysis. The IR and 1H NMR spectra of several chelates of two ligands L1 and L2 showed the involvement of the azo group in chelation with the transition metaI ions, in most of the studied chelates, and that the two ligands L1 and L2 showed the involvement of the azo group in chelation with the transition metal ions, in most of the studied chelates, and that the two ligands L1 and L2 were coordinated either in the enol or the keto form. IR spetra also showed that Fe(III)-, Ni(II)-, Mn(II)-, VO(II)-L1 and Cu(II)-L2 chelates behaved in a bidentate manner, in contrast with the two (1:1) M:L cobalt chelates with the two ligands are tridentate.TG analysis indicated the presence of three to twelve water molecules of hydration eliminated on heating up to 150℃ and one or two coordinated water molecules removed at 150~180℃.The octahedral structure is proposed fOr all the chelates, except Cu(II)-L2 and Ni(II)-L1 chelates which have square planar geometry, based on their electronic spectra

Size-Controllable Metal Chelates as Both Light Scattering Centers and Electron Collection Layer for High-Performance Polymer Solar Cells

An electron collection layer(ECL)between a photoactive overlay and an electrode plays a crucial role in optimizing the light field and charge extraction in bulk-heterojunction(BHJ)polymer solar cells(PSCs).However,the typical thickness of the photoactive layer is thinner than its optical path lengths,limiting further improvement of light absorption and device performance.

Air-Stable Ultrabright Inverted Organic Light-Emitting Devices with Metal Ion-Chelated Polymer Injection Layer

Here,this work presents an air-stable ultrabright inverted organic lightemitting device(OLED)by using zinc ionchelated polyethylenimine(PEI)as electron injection layer.The zinc chelation is demonstrated to increase the conductivity of the PEI by three orders of magnitude and passivate the polar amine groups.With these physicochemical properties,the inverted OLED shows a record-high external quantum efficiency of 10.0% at a high brightness of 45,610 cd m^(-2) and can deliver a maximum brightness of 121,865 cd m^(-2).Besides,the inverted OLED is also demonstrated to possess an excellent air stability(humidity,35%)with a half-brightness operating time of 541 h@1000 cd m^(-2) without any protection nor encapsulation.

Metal chelate affinity to immobilize horseradish peroxidase on functionalized agarose/CNTs composites for the detection of catechol

The paper reports a novel amperometric biosensor for catechol based on immobilization of a highly sensitive horseradish peroxidase by affinity interactions on metal chelate-functionalized agarose/carbon nanotubes composites. Metal chelate affinity takes advantage of the affinity of Ni2＋ ions to bind strongly and reversibly to histidine or cysteine tails found on the surface of the horseradish peroxidase. Thus, enzymes with such residues in their molecules can be easily attached to functionalized aga- rose/carbon nanotubes composites support containing a nickel chelate. Linear sweep voltammograms and amperometry are used to study the proposed electrochemical biosensor. Catechol is determined by direct reduction of biocatalytically liberated quinone species at -0.05 V （vs. SCE）. The effect ofpH, applied electrode potential and the concentration of H2O2 on the sensitivity of the biosensor has been investigated. The performance of the proposed biosensor is tested using four different phenolic compounds, showing very high sensitivity, in particular, the linearity of cateehol is observed from 2.0 × 10-8 to 1.05×10-5 M with a detection limit of 5.0×10-9 M.

Structure of Copper Chelate of 2-Hydroxy-4-methylthiobutanoic Acid as Trace Mineral Additive in Animal Feeding

The chelate complex of Cu2＋ with 2-hydroxy-（4-methylthio）butanoate（MHA-H, the anion derived from the so-called methionine hydroxy-analogue, largely used in animal nutrition as a source of methionine, MHA） is an efficient, bioavailable trace mineral additive for animal feeding. The structure of MHA-H copper chelate was investigated by single-crystal X-ray diffraction. The crystal structure（C10H18Cu O6S2, 1, monoclinic, space group P21/c, Z = 2, a = 16.158（4）, b = 4.9733（12）, c = 9.159（2） ？, β = 104.786（4）°） exhibits that two MHA-H ligands coordinate with a CuII ion to form a square-planar environment completed to an octahedron through interaction with carbonyl oxygens of neighboring molecules, which expand to constitute a two-dimensional sheet coordination network. And a separation between the hydrophilic and lipophilic moieties like micelles was found in the packing structure. X-ray powder diffraction and thermogravimetric analysis were used to study the phase purity of the bulk sample and thermostability of complex 1, respectively.

Synthesis and Characteristics of A Novel Heavy Metal Ions Chelator

Polyacrylamide-urea-sulfanilamide（PUS） was prepared as a novel heavy metal ions chelator and successfully used to simultaneously remove heavy metals from wastewater effluents.The effects of reaction parameters（sodium hydroxide,material ratio,temprature and contact time） were monitored to specify the best synthesis conditions.PUS was chemically characterized by means of infrared spectroscopy（FTIR） and ultraviolet-visible（UV-Vis）.The simultaneous chelation performance of PUS towards selected heavy metals ions,Ni2＋,Cu2＋,Pb2＋,Zn2＋,Cd2＋ was discussed,showing that Ni2＋,Cu2＋,Pb2＋,Zn2＋ could be better chelated.It is indicated that the synthesized PUS is a potential remediation material when used for the treatment of wastewater containing metal ions.

Chelation in Metal Intoxication XLIV: Efficacy of α-Mercapto β-(5-Substituted, 2-Furyl) Acrylic Acids in Mobilizing Intracellularly Bound Cadmium in Rat

The efficacy of α mercapto β (2_furyl) acrylic acid (MFA), α mercapto β (5_sodiumsulfonate, 2_furyl) acrylic acid (MSFA) and α mercapto β (5_acetoxymethyl, 2_furyl) acrylic acid (MAFA) to mobilize intracellularly bound cadmium in liver and kidney was investigated in rats pre_exposed to cadmium. MFA was effective in reducing cadmium levels of hepatic and renal supernatant cytosolic fraction (SCF) while MSFA and MAFA were effective in lowering cadmium levels of renal SCF and hepatic SCF respectively. All the chelating agents also enhanced the excretion of cadmium more in feces than in urine. However, substitution on the furan ring lowered cadmium mobilizing efficacy of the parent compound, MFA. The treatment with MFA did not affect the status of endogenous zinc and copper while the treatment with MSFA and MAFA enhanced their excretion. MSFA increased hepatic and renal zinc and renal copper while MAFA increased their copper levels.

Study on Treatment of Heavy Metals in Fly Ash by a Chelating Agent

The fly ash from two municipal solid waste incineration plants in Shanghai was treated by the self-developed organic composite chelating agent. The results indicated that the stabilization effect of Pb in the fly ash by the composite chelating agent was the best,and the proportions of its easily leaching form in the two kinds of fly ash decreased from 29. 60% and 27. 49% to 3. 05% and 0. 29% respectively. The leaching toxicity of stabilized fly ash was lower than the limits of Standard for Pollution Control on the Landfill Site of Municipal Solid Waste（ GB 16889- 2008）,so it can be landfilled separately in the landfill site of municipal solid waste.

Advances in the study of Alzheimer's disease

Alzheimer＇ s disease （AD） is the most common cause of dementia, and the only treatment currently available for the disease is acetylcholinesterase inhibitors. Recent progress in understanding the molecular and cellular pathophysiology of Alzheimer＇s disease has suggested possible pharmacological interventions, including acetylcholineseterase inhibitors; secretase inhibitors; cholesterol lowering drugs; metal chelators and amyloid immunization. The objective of this paper is to review the main drugs possibly used for AD and their future therapeutic effects.

DFT Investigation of Chelation of Divalent Cations by Some 4-Benzylidenamino-4,5-Dihydro-lH-1,2,4- Triazol-5-One Derivatives

The complexation of BDHTD （4-benzylidenamino-4,5-dihydro-lH-l,2,4-triazol-5-one derivatives） by divalent doubly charged metal ions M2＋ （M = Mg, Ca, Fe and Cu） has been investigated using the density functional method B3LYP. Two distinct coordination modes （k2-O,O and k2-O,N） have been taken into account. Geometry optimizations have been performed in gas-phase and solution-phase： acetonitrile and DMF （N,N-dimethylformamide） with the basis set 6-31G（d,p）. The B3LYP method was also used to calculate the stability and free energies of the 24 complexes of BDHTD with metal ions M2＋ （M = Mg, Ca, Fe and Cu） respectively in gas-phase and solution-phase： acetonitrile and DMF. Results indicate that k2-O,N structures are most stable in gas-phase. The influence of substitution on the stability is sensitive in solution-phase. The interaction energies of complexation process in various media have been calculated at B3LYP/6-31G（d,p） and CCSD（T） level. The MIA （metal ion affinity） of BDHTD with M2＋ （M = Mg, Ca, Fe and Cu） in various media has been explored. The results show that the M1A highly varies with the coordination mode and substitution effect. From the calculated Gibb energies of complexation in various media, it is revealed that the complexation is possible in gas in acetonitrile. The ligand＇s affinity toward individual cation M2＋ （M = Mg, Ca, Fe and Cu） has been analysed. A significant reduce of BDEs observed confirms the decrease of the antioxidant activity by the metal chelation. The charge transfer induced by metal chelation is examined using the NBO analysis.

Phenolic Contents and Antioxidant Activities of Green Tea with and without Lemon

Tea is the most widely consumed beverage throughout the world, after water and is considered as a good antioxidant nutrient against free radical reactions. Lemons are citrus fruits that are very common in many parts of the world and are well known for their health benefits. In this study, different assays were used to evaluate total phenolic content and antioxidant activities of green tea with and without lemon. Our results showed that green tea with lemon has higher phenolic content, stronger reducing power than green tea without lemon;and exhibits a significant inhibition of 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and hydrogen peroxide (H2O2). However, both samples exhibited high ferrous chelating activity with no significant difference among each other indicating a good antioxidant potential for both. This is a comparative study between green tea and green tea supplemented with lemon. The study contributes to a better understanding about how the addition of supplements like lemon might influence the antioxidant activity of tea.

Metal chelation reduces skin epithelial inflammation and rescues epithelial cells from toxicity due to thermal injury in a rat model

Background:One of the most pervasive complications of burn injury is wound progression,characterized by continuous tissue destruction in untreated wounds,which leads to wound infection,inflammation,oxidative stress and excessive scar formation.We determined whether additional tissue destruction could be attenuated with Livionex formulation(LF)lotion,which contains a metal-chelating agent and reduces inflammation in burn wounds.Methods:We subjected male Sprague Dawley rats to a 2%total body surface area(TBSA)burn using a brass comb model and topically applied LF lotion(containing ethylenediaminetetraacetic acid and methyl sulfonyl methane)to the affected area every 8 hours over 3 days.Inflammatory cytokine levels,cell apoptosis and wound healing were compared in LF lotion-treated and untreated rats.Statistical analysis was performed using a one-way analysis of variance in conjunction with Tukey’s post-hoc test.Results:Serum inflammatory cytokines were not detectable after 3 days,suggesting that small burn wounds induce only an immediate,localized inflammatory response.Microscopy revealed that LF lotion improved burn site pathology.Deoxynucleotidyl transferase biotin-d-UTP nick-end labeling staining showed reduced cell death in the LF-treated samples.LF lotion prevented the spread of tissue damage,as seen by increased amounts of Ki-67-positive nuclei in the adjacent epidermis and hair follicles.Tumor necrosis factor-alpha,interleukin-6 and inducible nitric oxide synthase levels in LF-treated skin sections from burned rats were comparable to the levels observed in unburned control sections,indicating that LF lotion reduces inflammation in and around the burn site.Conclusions:These results establish LF lotion as a therapeutic agent for reducing inflammatory stress,cell death and tissue destruction when applied immediately after a burn injury.Further studies of LF lotion on large TBSA burns will determine its efficacy as an emergency treatment for reducing long-term morbidity and scarring.

Fast removal of heavy metal ions and phytic acids from water using new modified chelating fiber

The graft copolymerization of acrylic acid（AA） onto polyethylene glycol terephthalate（PET） fiber initialed by benzoy peroxide （BPO） was carried out in heterogeneous media.Moreover,modification of the grafted PET fiber（PET-AA） was done by changing the carboxyl group into acylamino group through the reaction with dimethylamine.The modified chelating fiber（NDWJN1） was characterized using elementary analysis,SEM and FT-IR spectroscopy.Adsorption kinetic curves indicated that NDWJNl could fast remove heavy metal ions and phytic acids from water effectively.Furthermore,batch kinetic studies indicated that heavy metal ions adsorbed to NDWJNl could be filted well by both pseudo-first-order and pseudo-second-order adsorption equations,but the intra-particle diffusion played a dominant role in the adsorption of phytic acids.

New generation Amberlite XAD resin for the removal of metal ions: A review

The direct determination of toxic metal ions, in environmental samples, is difficult because of the latter＇s presence in trace concentration in association with complex matrices, thereby leading to insufficient sensitivity and selectivity of the methods used. The simultaneous removal of the matrix and preconcentration of the metal ions, through solid phase extraction,serves as the promising solution. The mechanism involved in solid phase extraction（SPE）depends on the nature of the sorbent and analyte. Thus, SPE is carried out by means of adsorption, ion exchange, chelation, ion pair formation, and so forth. As polymeric supports, the commercially available Amberlite resins have been found very promising for designing chelating matrices due to its good physical and chemical properties such as porosity, high surface area,durability and purity. This review presents an overview of the various works done on the modification of Amberlite XAD resins with the objective of making it an efficient sorbent. The methods of modifications which are generally based on simple impregnation, sorption as chelates and chemical bonding have been discussed. The reported results, including the preconcentration limit, the detection limit, sorption capacity, preconcentration factors etc., have been reproduced.

Determination of Tetracyclines in Honey Using Liquid Chromatography with Ultraviolet Absorbance Detection and Residue Confirmation by Mass Spectrometry

A determination method has been optimized and validated for the simultaneous analysis of tetracycline （TC）, oxytetracycline （OTC）, chlortetracycline （CTC） and doxycycline （DC） in honey. Tetracyclines （TCs） were removed from honey samples by chelation with metal ions bound to small Chelating Sepharose Fast Flow columns and eluted with Na2EDTA-Mcllvaine pH 4.0 buffers. Extracts were further cleaned up by Oasis HLB solid-phase extraction （SPE）, while other solid-phase extraction cartridges were compared. Chromatographic separation was achieved using a polar end-capped C 18 column with an isocratic mobile phase consisting of oxalic acid, acetonitrile and methanol. LC with ultraviolet absorbance at 355 nm resulted in the quantitation of all four tetracycline residues from honey samples fortified at 15, 50, and 100 ng/g, with liner ranges for tetracyclines of 0.05 to 2 μg/mL. Mean recoveries for tetracyclines were greater than 50% with R.S.D. values less than 10% （n= 18）. Detection limits of 5, 5, 10, 10 ng/g for oxytetracycline, tetracycline, chlortetracycline and doxycycline, respectively and quantitation limits of 15 ng/g for all the four tetracyclines were determined. Direct confirmation of the four residues in honey （2-50 ng/g） was realized by liquid chromatography-tandem mass spectrometry （LC/MS/MS）. The linear ranges of tetracyclines determined by LC/MS/MS were between 5 to 300 ng/mL, with the linear correlation coefficient r〉 0.995. The limits of detection of 1 to 2 ng/g were obtained for the analysis of the TCs in honey.

Investigation of hydrolysis conditions and properties on protein hydrolysates from flatfish skin

Response surface method （RSM）, based on Box-Behnken design, was used to optimize the enzymatic hydrolysis conditions of flatfish skin protein hydrolysates （FSPH）. Among the tested proteases, the combination of nutrase and trypsin was selected. The optimal hydrolysis conditions were as follows： pH 7.3, temperature 51.8℃, and the enzyme/substrate （E/S） ratio 2.5; under these conditions, the maximum peptide yield （PY） was 69.41 =1：0.43%. The physiochemical analysis showed that the amino acids （His, Asp and Glu） of FSPH accounted for 18.15%, and FSPH was a mixture of polypeptides mostly distributed among 900-2000 Da. FSPH could exhibit a 93% chelating effect on ferrous ion at a concentration of 400 gg/mL, and also a notable reducing power. This study showed bioprocess for the production of FSPH for the first time, which had a good potential for valuable ingredients in the food, cosmetic and medicine industries.

Synthesis, Structural Characterization, and Antimicrobial Activities of Mn（II）, Co（II）, Ni（II）, Cu（ll） and Zn（II） Complexes of Triazole-based Azodyes

The synthesis and characterization of new transition metal complexes of Mn（ll）, Co（II）, Ni（II）, Cu（II） and Zn（II） with 3-（2-hydroxynaph-l-ylazo）-1,2,4-triazole （HL1） and 3-（2-hydroxy-3-carboxynaph-l-ylazo）-1,2,4-triazole （HL2） have been carried out. Their structures were confirmed by elemental analyses, thermal analyses, spectral and magnetic data. The IR and 1H NMR spectra indicated that HL1 and HL2 coordinated to the metal ions as bidentate monobasic ligands via the hydroxyl O and azo N atoms. The UV-Vis, ESR spectra and magnetic moment data revealed the formation of octahedral complexes [MnL1（AcO）（H2O）3] （1）, [CoL1（AcO）（HzO）3]·H2O （2）, [MnL2- （AcO）（H20）3] （6） and [CoL2（AcO）（H2O）3] （7）, [NiL1（AcO）（H2O）] （3）,[ZnLI（AcO）（HzO）]·H2O （5）, [NiL2- （AcO）（H2O）] （8）, [ZnL2（AcO）（H2O）]·H2O （10） have tetrahedral geometry, whereas [CuLI（AcO）（H2O）2] （4） and [CuL2（AcO）（H2O）2]·5H2O （9） have square pyramidal geometry.. The mass spectra of the complexes under EI-con- ditions showed the highest peaks corresponding to their molecular weights, based on the atomic weights of 55Mn, 59Co, 58Ni, 63Cu and 64Zn isotopes; besides, other peaks containing other isotopes distribution of the metal. Kinetic and thermodynamic parameters of the thermal decomposition stages were computed from the thermal data using Coats-Redfern method. HL2 and complexes 6--10 were found to have moderate antimicrobial activities against Staphylococcus＇ aureus （gram positive）, Escherichia coli （gram negative） and Salmonella sp bacteria, and antifungal activity against Fusarium oxysporum, Aspergillus niger and Candida albicans. Also, in most cases, metallation increased the activity compared with the free ligand.