Optimal dietary copper requirements and relative bioavailability for weanling pigs fed either copper proteinate or tribasic copper chloride

Background: The objective of this study was to determine the effects of supplementing Cu on growth performance, Cu metabolism and Cu-related enzyme activities of weanling pigs fed diets with two different Cu sources, and to estimate optimal Cu requirements and relative bioavailability from these two sources for pigs.Methods: Weanling pigs were allocated to 14 treatments arranged factorially, including 6 added Cu levels(5, 10,20, 40, 80, 160 mg/kg), and 2 mineral sources(tribasic Cu chloride, TBCC and copper proteinate, Cu Pro), as well as one negative control(0 mg/kg added Cu level) and one maximum allowed level treatment(200 mg/kg TBCC) for the entire 38-d experiment. Growth performance, mineral status and enzyme activities were measured at the end of this study.Results: Increasing levels of Cu showed linear and quadratic responses(P < 0.01) for final BW, ADG and FCR regardless of the sources. Supplementation with TBCC(> 80 mg/kg) and Cu Pro(> 20 mg/kg) significantly decreased(P < 0.05) diarrhea incidence of weanling pigs. There were linear and quadratic increases(P < 0.01) in bile, hepatic,and intestinal Cu concentrations, fecal Cu contents, and plasma enzyme activities(alkaline phosphatase,ceruloplasmin, Cu, Zn-Superoxide dismutase(Cu/Zn SOD), and glutathione peroxidase), whereas plasma malondialdehyde decreased(P < 0.01) linearly and quadratically as dietary Cu level increased. Similarly, pigs fed Cu Pro absorbed and retained more Cu and excreted less Cu than those fed TBCC when supplemented 80 mg/kg and above. Optimal dietary Cu requirements for pigs from 28 to 66 d of age estimated based on fitted broken-line models(P < 0.05) of bile Cu, plasma Cu/Zn SOD and growth performance were 93–140 mg/kg from TBCC, and 63–98 mg/kg from Cu Pro accordingly. According to slope ratios from multiple linear regression, the bioavailability value of Cu Pro relative to TBCC(100%) was 156–263%(P < 0.01).Conclusion: The findings indicated that Cu recommendation from current NRC(5–6 mg/kg) was not sufficient to meet the high requirement of weanling pigs. Cu from Cu Pro was significantly more bioavailable to weanling pigs than TBCC in stimulating growth and enzyme activities, decreasing diarrhea frequency and fecal Cu contents to the environment.

Effect of noncovalent complexations on coordination interactions in a tricomponent system ofβ-cyclodextrin,copper chloride and hexamethylene tetramine

This study reveals that the noncovalent complexation betweenβ-CD and Cu（HMTA）^（2＋） makes a positive contribution to the coordination interaction between Cu^（2＋） and HMTA in a tricomponent system.Besides,mono- and binuclear complexes：[β-CDCu]~＋ and[Cu·β-CDCu]~＋ were observed under the condition of ESI-MS.

Deprotection of t-Butyldimethylsiloxy (TBDMS) Protecting Group with Catalytic Copper (II) Chloride Dihydrate

t-Butyldimethylsilyl (TBDMS) ether can be cleaved upon refluxing in acetone/H2O (95 : 5) in the presence of a catalytic amount of copper (II) chloride dihydrate (5 mmol %).

Oxidation of 2,2'-Dihydroxy-3,3'-di-tert-buty-5,5'-dimethoxyl-biphenyl to 3,3'-Di-tert-butylbiphenyl-2,5,2',5'-diquinone with Copper(Ⅱ)Chloride as Catalyst:Synthesis,Structure and Spectral Properties of Diquinone

Use of free air as oxidant and copper（II）chloride as catalyst,3,3＇-di-tert-butylbi-phenyl-2,5,2＇,5＇-diquinone（BBDQ）was prepared via catalytic oxidation of 2,2＇-dihydroxy-3,3＇-di-tert-butyl-5,5＇-dimethoxy-biphenyl（di-BHA）.The yield of reaction attained 95% and the selectivity for BBDQ was 100%.The single-crystal X-ray diffraction analysis reveals that the dihedral angle between two rings（benzene rings for di-BHA and quinone rings for BBDQ）changes from 89.8 to 45.3o,indicating the steric hindrance effects of methyl disappear in the oxidation process.The crystal structures of di-BHA and BBDQ are further confirmed by their spectral characterizations.The probable mechanism for this oxidation process is also discussed.

Dissolution of Nickel in Copper Residue Generated from Nickel Matte Refining

The dissolution behavior of nickel during the oxygen chloride leaching of the copper residue was investigated.Technological variables of the leaching,including oxygen flow rate,concentrations of chloride and sulfuric acid,and temperature,were discussed.

Synthesis and Crystal Structure of Cobalt(Ⅱ) and Copper(Ⅱ) Complexes Involving L-Aamino Alcohols

Two novel L-amino alcohol coordination cobalt and copper complexes I and Ⅱ were obtained separately from the direct reaction of L-plenylglycinol with Co（Ⅱ） acetate tetrahydrate in anhydrous ethanol and L-leucinol with Cu（Ⅱ） chloride dihydrate in anhydrous methanol. The structures of I and Ⅱ were determined by single-crystal X-ray diffraction and further characterized by elemental analysis and IR. For I： [Co3（C51H66N3O16）]2（OAc）, monoclinic, space group P21, a = 15.022（3）, b = 14.242（3）, c = 28.922（6） A, β = 98.944（4）°, V = 6112（2） A3, Z = 4, Dc = 1.339 g/cm^3, the final R = 0.0860 for 21906 observed reflections with I 〉 2（I）. For Ⅱ： Cu2[C24H58N4O7Cl]Cl, orthorhombic, space group P212121, a = 6.1861（13）, b = 20.838（4）, c = 28.274（6） , V = 3644.6（13） 3, Z = 4, Dc = 1.310 g/cm^3, the final R = 0.0642 for 11106 observed reflections with I 〉 2（I）. The complexes were then used to catalyze the Henry reaction and catalytic activity determined by 1H NMR.

Electron-deficient Cu site catalyzed acetylene hydrochlorination

Rational design of catalytic sites to activate the C≡C bond is of paramount importance to advance acetylene hydrochlorination. Herein, Cu sites with electron-rich and electron-deficient states were constructed by controlling the impregnation solutions. The π electrons flowing from acetylene to Cu site are facilitated over the electron-deficient Cu sites, achieving high activation of C≡C bond. The contradiction between the increased activation of acetylene required for enhanced catalytic activity and the resistance of Cu site to reduction by acetylene required for maintaining catalytic stability can be balanced by establishing strong interactions of Cu site with pyrrolic-N species. The catalytic activity displays a volcano shape scaling relationship as a function of Cu particle size. Tribasic copper chloride is concomitantly generated with the construction of electron-deficient Cu sites. The H–Cl bond of HCl can be activated over the tribasic copper chloride, accelerating the surface reaction of vinyl chloride production. This strategy of inducing electron deficiency provides new insight into the rational design of catalysts for the synthesis of vinyl chloride with a high catalytic performance.

Synthesis and Structural Characterization of Di(2-amino-5-methyl-1,8-naphthyridin-1-ium-7-carboxylato)dichlorocuprate(Ⅱ) Dihydrate

Di（2-amino-5-methyl-1,8-naphthyridin-1-ium-7-carboxylato）dichlorocuprate（Ⅱ） di- hydrate has been prepared from 5,7-dimethyl-1,8-naphthyridine-2-amine, CuCl2·2H2O and concentrated hydrochloride acid, and its structure was determined by X-ray diffraction at 298 K. The compound （C20H22Cl2CuN6O6, Mr = 576.88） crystallizes in monoclinic, space group P21/n with a = 9.102（9）, b = 12.150（12）, c = 10.619（10） A,β = 91.20°, V= 1174.1（19） A^3, Z= 2, Dc= 1.632 g/cm^3, F（000） = 590,μ = 1.208 mm^-1, R = 0.0392 and wR = 0.0984. The Cu^2＋ ion is six-coordinated by two nitrogen and two oxygen atoms from two different naphthyridine ligands at the equatorial positions together with two chloride ions located at the axial positions.

Highly efficient solvent-free synthesis of quinazolin-4(3H)-ones and 2,3-dihydroquinazolin-4(1H)-ones using tetrabutylammonium bromide as novel ionic liquid catalyst

A simple and efficient procedure for the synthesis of 2-arylquinazolin-4（3H）-ones has been developed through cyclocondensation of 2-aminobenzamide with aromatic aldehydes using tetrabutylammonium bromide（TBAB） as novel neutral ionic liquid catalyst in the presence of copper（Ⅱ） chloride（CuCl;） as oxidizing agent under solvent-free conditions at 100℃.In the absence of CuCl;and under a nitrogen atmosphere,the unoxidized intermediates,2-aryl-2,3-dihydroquinazolin-4（1H）-ones,were isolated. Treatment of these intermediates with CuCl;in TBAB media gave the oxidized products 2-arylquinazolin-4（3H）-ones.On the other hand,cyclocondensation of 2-aminobenzamide with aromatic aldehydes in TBAB under microwave irradiation directly gave 2- arylquinazolin-4（3H）-ones.

Chlorine-induced mixed valence of CuO_(x)/C to promote the electroreduction of carbon dioxide to ethylene

Electrochemical conversion of CO_(2)(CO_(2)RR)into high-value fuel is identified as one of the promising approaches to achieve carbon neutrality.The synthesis of high-efficiency CO_(2)reduction electrocatalysts with high C_(2):C_(1) selectivity remains a field of intense interest.Previous studies have shown that the presence of Cu(I)is beneficial for the reduction of CO_(2)into C_(2)products.However,the stable presence of Cu(I)remains controversial,especially in the negative potential window.Here we report a simple and easily scalable catalyst precursor Cu_(2)(OH)_(3)Cl/C,which automatically forms in-situ chlorine-doped Cu/Cu_(2)O heterointerface during electrocatalysis.The catalyst not only exhibits a Faradaic efficiency of 33.03%but also provides a long-term stability of Cu^(+),gaining a stable electrolysis of 11 h,with an ethylene/methane ratio over 50.The experimental results and mechanistic studies confirm that the presence of Cl^(-)inhibits the reduction of Cu^(+),inducing the formation of Cu^(0)/Cu^(+),and reduces the reaction energy of the intermediate ^(*)CO dimerization,thereby facilitating the formation of C_(2)products.This work provides a feasible way to synthesize copper ions with long-term and stable positive charge in CO_(2)RR and expands a new way to synthesize ethylene industrial products in the future.