非洲猪瘟疫情形势下生长育肥猪饲养管理关键技术

育肥猪的科学饲养与管理直接影响猪场经济效益,非洲猪瘟疫情形势下的育肥猪生产更是充满挑战与压力。文章旨在针对生长育肥猪养殖的基本环节及操作要点,从环境控制、科学饲养与管理、严格防疫等方面阐述了育肥猪养殖的关键技术,为非洲猪瘟疫情防控形势下的生猪保供复产提供技术支撑。

Hierarchical and self-supporting honeycomb LaNi_5 alloy on nickel foam for overall water splitting in alkaline media

Ni-based metallic foams possessing large specific surfaces and open cell structures are of specific interest as catalysts or catalyst carriers for electrolysis of water.Traditional fabrication of Nickel foam limits the element modification choices to several inert transition metals only on polymer foam precursor and subsequent preparation of foam-based catalysts in aqueous solution or organic electrolyte.To expand the modification horizon,molten salt with wide electrochemical window and fast ion diffusion can achieve the reduction of highly active elements.Herein,we reported is a general and facile method to deposit directly of highly reactive element La and prepare hierarchical honeycomb LaNi_(5) alloy on Ni foam(ho-LaNi_(5)/NF).This self-supporting electrode presents excellent electrical coupling and conductivity between the Ni foam and LaNi_(5),which provides a 3D self-supported heterostructure with outstanding electrocatalytic activity and excellent durability for the hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).It exhibits excellent overpotential(1.86 V)comparable to commercial coupled IrO_(2)//Pt/C(1.85 V)at a high current density of 100 m A cm^(-2).This work may pave the way for fabricating novel 3D self-supported honeycomb alloy that can be applied as electrode for usage of clean energy.

Germylene-Fe complexes caused by heterometallic coupling and investigation into the 3d-4p bonding

The interpretation of heterometallic bonding nature is a basic work of inorganic chemistry.By means of intermetallic substitution of germylene anions with iron halide complexes CpFe(CO)_(2)I andβ-diketiminato Fe^Ⅱchloride,the ferrogermylene complexes 3a,3b and 4a were synthesized and structurally characterized.The structural and IR characterizations show the presence of the Ge←Feπbackbonding in molecules 3a,3b and 4a.The computational works on frontier molecular orbitals and their comparison of energy states confirmed thatσdonation andπbackbonding are both weak in these molecules,despite three complexes have longer Ge-Fe bonds,whose strength decreases slightly with the degressive electron density around Fe environment in a sequence from 3a,3b to 4a.

金属有机骨架材料在锕系阳离子吸附应用中的构效关系

近年来,随着核能在我国的崛起和发展,开发简单、高效、应用性强的吸附材料用于锕系阳离子的吸附分离变得愈加迫切.金属有机框架材料(metal-organic frameworks,MOFs)由于其合成简单、结构可控、功能易调、孔隙率高、比表面积大等特点被认为在锕系阳离子吸附分离领域具有广阔的应用前景.本文从材料设计角度出发,综述了MOFs用于锕系阳离子吸附分离的最新研究进展,着重讨论了表面修饰、缺陷、功能复合、金属节点等对MOFs吸附性能的影响,以厘清MOFs材料在锕系阳离子吸附应用中的构效关系.最后,提出了目前MOFs用于锕系阳离子吸附分离存在的问题,并对未来的相关研究方向进行了展望.

Efficacious selective separation of U(Ⅵ) over Mo(Ⅵ) using novel 2,9-diamide-1,10-phenanthroline ligands: Liquid-liquid extraction and coordination chemistry

Uranium and molybdenum are important strategic elements. The production of ^(99)Mo and the hydrometallurgical process of uranium ore face difficult problems of separation of uranium and molybdenum.In this study, the four phenanthroline diamide ligands were synthesized, and extraction and stripping experiments were performed under different conditions to evaluate the potential application of these ligands for separation of U(Ⅵ) over Mo(Ⅵ). With the growth of alkyl chain, the solubility of ligands could be greatly improved, and the separation effect of U(Ⅵ) over Mo(Ⅵ) gradually increased. The SF_(U/Mo) were around 10,000 at 4 mol/L HNO3. Three stripping agents were tested with the stripping efficiency of Na_(2)CO_(3)(5%) > H_(2)O > HNO_(3)(0.01 mol/L). The stripping percentages of the three stripping agents were all close to unity, indicating that the ligands had the potential to be recycled. The chemical stoichiometry of U(Ⅵ) complexes with ligands was evaluated as 1:1 using electrospray ionization mass spectrometry,ultraviolet visible spectroscopy and single-crystal X-ray diffraction. The consistency between theoretical calculation and experimental results further explains the coordination mechanism.

Magnetic KIT-6 nano-composite and its amino derivatives as convenient adsorbent for U(Ⅵ)sequestration

Although mesoporous silica with magnetically hybridized two-dimensional channel structures has been well studied in recent years,it remains a challenge to fabricate the counterpart with macroporous three-dimensional cubic structures since the highly acidic preparation conditions lead to dissolution of magnetic particles.Herein,we successfully prepared magnetic KIT-6 nano-composite and its amino derivatives by bearing acid-resistant iron oxide.The prepared materials exhibited excellent properties for U(VI)ions removal from aqueous solutions under various conditions.The experimental data show that the U(VI)adsorption features fast adsorption kinetics,high adsorption capacity and ideal selectivity toward U(VI).The adsorption process is of spontaneous and endothermic nature and ionic strength independence,and the adsorbents can be easily regenerated by acid treatment.Compared to pristine KIT-6,the introduction of magnetism does not reduce the efficiency of the material to remove U(VI)while exerting its role as a recovery adsorbent.The findings of this work further demonstrate the potential broad application prospects of magnetic hybrid mesoporous silica in radionuclide chelation.

Heterostructure engineering of MoS_(2)/Mo_(2)CT_(x) nanoarray via molten salt synthesis for enhanced hydrogen evolution reaction

Two-dimensional layered transition metal carbides(MXenes),have huge potential advantage for applications in hydrogen evolution reaction(HER).However,the hindered hydrogen evolution at large current densities and the instability of MXenes during HER remains major challenges.Herein,we report the MoS_(2)/Mo_(2)CT_(x) nanoarray with aerophobic structure via molten salt synthesis.In situ vertical distribution of MoS_(2)nanoarray on the surface of Mo_(2)CT_(x) accelerates hydrogen gas release from the electrode,exhibiting significantly enhanced catalytic activity and stability to bare MoS_(2)and Mo_(2)CT_(x).The MoS_(2)/Mo_(2)CT_(x) nanoarray possesses excellent stability at100 mA/cm^(2)for 100 h with only 3%overpotential increase.Our work provides guidance for developing high-stability MXene-based catalysts by virtue of in situ bonding between nanoarray and MXene.

Synthesis of novel nanomaterials and their application in efficient removal of radionuclides

With the development of nuclear energy, large amounts of radionuclides are inevitably released into the natural environment. It is necessary to eliminate radionuclides from wastewater for the protection of environment. Nanomaterials have been considered as the potential candidates for the effective and selective removal of radionuclides from aqueous solutions under complicated conditions because of their high specific surface area, large amounts of binding sites, abundant functional groups, pore-size controllable and easily surface modification. This review mainly summarized the recent studies for the synthesis, fabrication and surface modification of novel nanomaterials and their applications in the efficient elimination and solidification of radionuclides,and discussed the interaction mechanisms from batch experiments, spectroscopy analysis and theoretical calculations. The sorption capacities with other materials, advantages and disadvantages of different nanomaterials are compared, and at last the perspective of the novel nanomaterials is summarized.

Easily prepared and stable functionalized magnetic ordered mesoporous silica for efficient uranium extraction

Functionalized magnetic Fe_3O_4@SiO_2 composite nanoparticles were prepared by simply embedding iron oxide nanoparticles into MCM-41 through one-step synthesis process, followed by aminopropyls grafting on the mesopore channels, aiming to efficiently and conveniently uptake U(VI) from aqueous solution. The resultant material possesses highly ordered mesoporous structure with large surface area, uniform pore size, excellent thermal stability, quick magnetic response, and desirable acids resistance, confirmed by Fourier transform infrared spectroscopy(FTIR), scanning electron microscopy(SEM), N_2 adsorption/desorption experiments, powder X-ray diffraction(PXRD), and thermogravimetric analysis(TGA). Detailed U(VI) sorption test indicated that this material is indeed an effective U(VI) sorbent with fast sorption kinetics of less than 2 h, large sorption capacity of 160 mg/g at p H 5.0±0.1, and desirable selectivity towards U(VI) ions over a range of competing metal ions. The absorbed U(VI) can be easily desorbed by 0.01 mol/L or more concentrated HNO_3 solution, and the reclaimed sorbent can be reused with no obvious decrease of sorption capacity even after 4 sorption-desorption cycles. The present results suggest the vast opportunities of this kind of magnetic composite on the solid-phase extraction of U(VI).

Kinetics process of Tb(Ⅲ)/Tb couple at liquid Zn electrode and thermodynamic properties of Tb-Zn alloys formation

Electrochemical properties of rare-earth elements in the LiCl-KCl eutectic are important for the pyrometallurgical recycling process of spent nuclear fuels. In this work, the electrochemical properties of Tb(Ⅲ)/Tb(0) couple were studied by the cyclic voltammetry(CV) at a liquid Zn pool electrode. The results showed that this electrochemical reaction is quasi-reversible with mixed reversible diffusion control and the charge transfer control. The diffusion coefficient of Tb(Ⅲ) was determined to be in the order of ~10.5 cm2 s.1. Moreover, kinetic parameters, such as the standard rate constants(ks) and charge transfer coefficient(α) for the electroreduction of Tb(Ⅲ) to Tb(0) at the liquid Zn electrode, were calculated by the Nicholson method at 873 K. Additionally, it was found that Tb-Zn intermetallic compounds were easily to be formed in the measurements. Hence, the reduction process of Tb(Ⅲ)/Tb(0) couple on the Zn-coated Mo electrode was also studied to obtain more information of the Tb-Zn intermetallic compounds. Electrochemical signals stemming from various intermetallic compounds associated with TbZn12, Tb2Zn17, Tb13Zn58, Tb3Zn11, TbZn3, TbZn2 and TbZn, were observed. The thermodynamic data were thereafter estimated by applying the emf method at 823–923 K. The standard formation Gibbs energies and the standard equilibrium constant of each Tb-Zn intermetallic compounds were also calculated. Finally, enthalpies and entropies of formation and the apparent standard potentials of various Tb-Zn intermetallic compounds were also obtained.

Phosphonate-Decorated Covalent Organic Frameworks for Actinide Extraction: A Breakthrough Under Highly Acidic Conditions

Although solid-phase extraction is a useful approach for metal ion separation from aqueous solutions,existing sorbents suffer from low extraction effici-encies and/or instability when in contact with strong acidic media.We report here the first study on rational design and fabrication of phosphonate-decorated covalent organic frameworks,COF-IHEP1 and COF-IHEP2,for efficient and selective extraction of of uranium(VI)[U(VI)]and plutonium(IV)[Pu(IV)]from highly acidic solutions.

Facile Access to Uranium and Thorium Phosphaethynolate Complexes Supported by Tren: Experimental and Theoretical Study

The issue of covale nee of acti nide complexes remai ns con troversial to date.The in troducti on of 2-phosphaethy nolate anion into acti・nide complexes is expected to in vestigate the reaction mode and the bon ding property.Herei n,we describe the function alizatio n of An(Tren^(TIPS))CI(1:An=U;2:An=Th)precursors with NaOCP(dioxane)_(2.5) through salt-elimination method leading to the formation of the corresponding uranium and thorium phosphaethynolate species:[U(Tren^(TIPS))(OCP)]⑶and[Th(Tren^(TIPS))(OCP)](4).

Professor Zhifang Chai:Scientific contributions and achievements

Prof.Zhifang Chai,born in October 1942,is a radioanalytical chemist working at the Institute of High Energy Physics,Chinese Academy of Sciences and Soochow University.He graduated from Fudan University in 1964.As an Alexander von Humboldt Foundation fellow,he worked at Cologne University,Germany from1980 to 1982.

Theoretical studies on the complexation of Eu(Ⅲ) and Am(Ⅲ) with HDEHP： structure, bonding nature and stability

Separation of trivalent lanthanides(Ln(Ⅲ)) and actinides(An(Ⅲ)) is a key issue in the advanced spent nuclear fuel reprocessing. In the well-known trivalent actinide lanthanide separation by phosphorus reagent extraction from aqueous komplexes(TALSPEAK) process, the organophosphorus ligand HDEHP(di-(2-ethylhexyl) phosphoric acid) has been used as an efficient reagent for the partitioning of Ln(Ⅲ) from An(Ⅲ) with the combination of a holdback reagent in aqueous lactate buffer solution. In this work, the structural and electronic properties of Eu^(3+) and Am^(3+) complexes with HDEHP in nitric acid solution have been systematically explored by using scalar-relativistic density functional theory(DFT). It was found that HDEHP can coordinate with M(Ⅲ)(M=Eu, Am) cations in the form of hydrogen-bonded dimers HL_2^-(L=DEHP), and the metal ions prefer to coordinate with the phosphoryl oxygen atom of the ligand. For all the extraction complexes, the metal-ligand bonds are mainly ionic in nature. Although Eu(Ⅲ) complexes have higher interaction energies, the HL_2^- dimer shows comparable affinity for Eu(Ⅲ) and Am(Ⅲ) according to thermodynamic analysis, which may be attributed to the higher stabilities of Eu(Ⅲ) nonahydrate. It is expected that this work could provide insightful information on the complexation of An(Ⅲ) and Ln(Ⅲ) with HDEHP at the molecular level.

Hierarchical assembly of uranyl metallacycles involving macrocyclic hosts

Actinide metallacycles are an emerging class of functional coordination assemblies,but multi-level assembly from metallacycle units toward hierarchical supramolecular structures are still rarely investigated.In this work,we put forward a novel supramolecular inclusion-based method through introducing two macrocyclic hosts,cucurbit[7]uril(CB[7])and cucurbit[8]uril(CB[8])to facilitate hierarchical assembly of uranyl metallacycles with higher complexity,and successfully prepare two different kinds of uranyl metallacycle-based complexes with intriguing hierarchical structures,a CB[7]-based four-member molecular necklace([4]MN)and a CB[8]-involved ring-in-ring supramolecular polymer chain.The results obtained here prove the feasibility of supramolecular inclusion for regulating coordination assembly of uranyl metallacycles and related hierarchical structures.It is believed that this method can be used to achieve the construction of actinide coordination assemblies with higher structural complexity.

Towards understanding the correlation between UO_2^(2+) extraction and substitute groups in 2,9-diamide-1,10-phenanthroline

2,9-Diamide-1,10-phenanthroline(DAPhen)ligands represent a new family of tetradentate extractants given their strong affinity to actinides and the CHON principle.Among this family,N,N′-diethyl-N,N′-ditolyl-2,9-diamide-1,10-phenanthroline(Et-TolDAPhen),initially reported by us,exhibits excellent selectivity towards actinides(U,Th,Am,Pu)over lanthanides and thus can be potentially applied in the group actinide extraction(GANEX)process for the group separation of actinides.In this article,by tailoring the lengths of alkyl chains,we synthesized other four DAPhen ligands with different substitute groups in the diamide moieties,and characterized the relationship between properties and substitute groups of DAPhen ligand.The extraction results show that three of the ligands exhibit high performance in UO_2^(2+)extraction from an acidic solution and the extracted UO_2^(2+)can be easily stripped by only using ultrapure water.Spectrophotometry titration confirms that UO_2^(2+)combined with all the four ligands in 1:1 mode.The extended X-ray absorption finestructure(EXAFS)study shows that six donor atoms comprise the first equatorial shell of the UO_2^(2+)ions bonded by the DAPhen ligands,among which two nitrogen and two oxygen atoms are from the DAPhen ligand,while other two oxygen atoms are from one nitrate ions.This article promises to provide basic data for assessing the feasibility of this kind of DAPhen ligands applied in actinides separation from nuclear wastes.

Two tetravalent uranium silicate and germanate crystals with three membered single-ring by molten salt method:K_(2)USi_(3)O_(9)and Cs_(2)UGe_(3)O_(9)

Two tetravalent uranium silicate and germanate M_(2)U^(Ⅳ)T_(3)O_(9)(M=K,Cs;T=Si,Ge)crystals were crystalized under inert gas by molten salt flux growth method.K_(2)USi_(3)O_(9)(1)crystallizes in the monoclinic space group P1_(21)/n1 with lattice parameters a=7.1076?,b=10.4776?,c=12.2957?,γ=120°and V=915.67?^(3).Cs_(2)UGe_(3)O_(9)(2)crystallizes in a hexagonal space group P-6 with lattice constants of a=7.5138?,b=7.5138?,c=11.0114?,γ=120°and V=538.38?^(3).Bond valence calculations indicate tetravalent uranium in both structures,which contain three-membered single-ring T_(3)O_(9)^(6-) trimers.K_(2)USi_(3)O_(9) is the first uranium silicate that contains the Si_(3)O_(9)^(6-) trimers.

Temperature-responsive alkaline aqueous biphasic system for radioactive wastewater treatment

The treatment of anionic ^(99)TcO_(4)^(-)in the waste tank with high alkalinity is still very challenging.In this work,a new temperature-responsive alkaline aqueous biphasic system(ABS)based on(tri-n–butyl)-ntetradecyl phosphonium chloride(P_(44414)Cl)was developed to remove radioactive ^(99)TcO_(4)^(-).The phase transition mechanism was studied by cloud point titration,small-angel X-ray scattering,dynamic light scattering,and molecular dynamic simulations.As the Na OH concentration or temperature increased,the P_(44414)^(+)micelle could grow and aggregate.This micelle showed a particularly high affinity toward ReO_(4)^(-)/^(99)TcO_(4)^(-)compared to other competing anions and could directly extract more than 98.6%of ^(99)TcO_(4)^(-)from simulated radioactive tank waste supernatant.Furthermore,the loaded ^(99)TcO_(4)^(-)could be easily stripped by using concentrated nitric acid rather than metal salt-based reductants.This work clearly demonstrates that the alkaline ABS is a promising separation system for solving the technetium problem in the alkaline waste tank.

A ternary mechanism for the facilitated transfer of metal ions onto metal–organic frameworks: implications for the "versatility" of these materials as solid sorbents

Although metal–organic frameworks offer a new platform for developing versatile sorption materials,yet coordinating the functionality,structure and component of these materials remains a great challenge.It depends on a comprehensive knowledge of a“real sorption mechanism”.Herein,a ternary mechanism for U(Ⅵ)uptake in metal–organic frameworks was reported.Analogous MIL-100s(Al,Fe,Cr)were prepared and studied for their ability to sequestrate U(Ⅵ)from aqueous solutions.As a result,MIL-100(Al)performed the best among the tested materials,and MIL-100(Cr)performed the worst.The nuclear magnetic resonance technique combined with energy-dispersive X-ray spectroscopy and zeta potential measurement reveal that U(Ⅵ)uptake in the three metal–organic frameworks involves different mechanisms.Specifically,hydrated uranyl ions form outer-sphere complexes in the surface of MIL-100s(Al,Fe)by exchanging with hydrogen ions of terminal hydroxyl groups(Al-OH_(2),Fe-OH_(2)),and/or,hydrated uranyl ions are bound directly to Al(Ⅲ)center in MIL-100(Al)through a strong inner-sphere coordination.For MIL-100(Cr),however,the U(Ⅵ)uptake is attributed to electrostatic attraction.Besides,the sorption mechanism is also pH and ionic strength dependent.The present study suggests that changing metal center of metal–organic frameworks and sorption conditions alters sorption mechanism,which helps to construct effective metal–organic frameworks-based sorbents for water purification.

Highly delocalized endohedral metal in Gd@C2v（9）-C82 metallofullerenes co-crystallized with α-Se

A new Gd@C2v（9）-C82·2.5（S8）·0.5（CS2） co-crystal was prepared for the first time and characterized by single-crystal X-ray diffraction （XRD）. The analysis dearly showed that, even though the C2v（9）-C82 cage is fully ordered, the endohedral Gd atoms are highly disordered. This result indicates the presence of highly delocalized endohedral Gd atoms, which has never been reported before. Density functional theory （DFT） calculations were used to rationalize the XRD results. The calcula- tions reveal the presence of two local energy minima, a and b, with the latter existing as four conformers b1-b4. Whereas the energy difference between the two minima is calculated only - 10 kcal/mol, their interconversion is almost impossible due to a high energy barrier, of up to 35.98 kcal/mol. This suggests the existence of multiple low-energy positions for the endohedral Gd atom. In addition, a remarkable electron transfer from the C2d9）-C82 cage to the S8 moieties was demonstrated, which might result in a modified endohedral environment and further contribute to the occurrence of delocalized endohedral Gd atoms.