抑制剂对尿素转化及土壤中氮的影响研究

以草甸棕壤为基质进行室内培养试验结果表明,脲酶抑制剂与硝化抑制剂配合使用,明显地抑制了NH4+-N向NO3--N的转化。NBPT+DCD处理效果最好,可延缓硝态氮的释放高峰达40天以上;H1和HA都表现出较强的硝化抑制作用。H3和H2对硝态氮基本无影响。

影响土壤N_2O排放和CH_4吸收的主控因素的研究(英文)

本文于2000年7月,在实验室模拟条件下,以长白山阔叶红松林鲜土壤为对象,采用正交试验设计法对土壤进行培养实验,研究了影响土壤N2O排放和CH4吸收的主要因素。考察了温度、水分、pH值、NH4+及NO3-五因素对森林土壤N2O排放和CH4吸收的影响。实验结果显示:在本试验设计的因素、水平条件下,N2O排放速率、CH4吸收速率二者均与土壤pH值和温度这两个因素呈显著正相关。并且N2O排放速率与CH4吸收速率间呈显著线性正相关关。

与氮转化有关的土壤酶活性对抑制剂施用的响应

利用室内模拟培养试验 ,研究好气条件下施用尿素后土壤脲酶、硝酸还原酶、亚硝酸还原酶和羟胺还原酶活性对脲酶抑制剂氢醌 (HQ)与硝化抑制剂包被碳化钙 (ECC)和双氰胺 (DCD)组合 (HQ +ECC、HQ +DCD)的响应 .结果表明 ,HQ +DCD组合与其它抑制剂处理相比能更有效地降低土壤脲酶活性 ,增加硝酸还原酶、亚硝酸还原酶、羟胺还原酶活性 .不同处理土壤脲酶、亚硝酸还原酶和羟胺还原酶活性与土壤NH4 + 、NO3-、NH3 挥发和N2 O排放速率间存在不同形式的显著相关关系 .土壤脲酶、亚硝酸还原酶和羟胺还原酶活性之间亦存在不同形式的显著正相关关系 .

新型二维异核配位聚合物{[NdBi(cydta)(NO_3)_2(H_2O)_4]·2.5H_2O}_n的晶体结构与热分解

由Bi(Hcydta).5H2O和Nd(NO3).6H2O按1︰1的物质的量比,在水溶液中合成了含Bi(III)-Nd(III)的异核配位聚合物{[(NO3)Nd(H2O)4(μ3-cydta)Bi(μ-ONO2)].2.5H2O}n.用元素分析、红外光谱、热重-差热和X射线单晶衍射等手段对标题配合物的组成和结构进行了表征.该配合物属三斜晶系,空间群P1,晶胞参数:a=0.9235(3)nm,b=1.0902(4)nm,c=1.4253(5)nm,α=71.840(4)°,β=86.877(4)°,γ=76.991(4)°,Z=2,Mr=936.65,V=1.3284(8)nm3,Dc=2.342g.cm-3,μ=8.646mm-1,F(000)=900,最终偏离因子R1=0.0406,wR2=0.1124.在该配合物中,铋(III)与配体cydta4-的4O2N和1个硝酸根中1个O原子以及邻位分子的硝酸根形成8配位的畸变双帽三棱柱.钕(III)与4个水分子的O,1个硝酸根中2个O以及来自3个不同配体cydta4-的桥联羧基O结合,形成9配位的三帽三棱柱构型.羧酸根在Bi—Nd和硝酸根在Bi—Bi间的桥联作用...

Sonochemical synthesis of monodispersed KY3F10 : Eu3+ nanospheres with bimodal size distribution

Monodispersed KY3F10:Eu3+ nanospheres with bimodal size distribution have been successfully synthesized via a facile and efficient sonochemical method in a surfactant-free system. Rare-earth nitrate (Y, Eu)(NO3)(3) and potassium fluoborate (KBF4) were used as precursors. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and photoluminescence (PL) spectra were used to characterize the samples.

Facile synthesis and luminescence properties of octahedral YVO4:Eu3+ microcrystals

Uniform octahedral YVO4:Eu3+ microcrystals have been successfully prepared through a designed two-step hydrothermal conversion method. One-dimensional precursor Y4O(OH)(9)NO3 was first prepared through a simple hydrothermal process without using any surfactant, catalyst or template. Subsequently, well-defined octahedral YVO4 was synthesized at the expense of the precursor during a hydrothermal conversion process. XRD results demonstrate that the diffraction peaks of the final product can be well indexed to the pure tetragonal phase of YVO4.

Solvent impregnated resin prepared using task-specific ionic liquids for rare earth separation

A novel bifunctional task-specific ionic liquid (TSIL), i.e. [trialkylmethylammonium][sec-nonylphenoxy acetate] ([A336] [CA-100]) was impregnated on intermediate polarized XAD-7 resin, and the prepared solvent impreganated resin (SIR) was studied for rare earth (RE) separation. Adsorption ability of the SIR was indicated to be obviously higher than that prepared by [A336][NO3] because of the functional anion of [A336][CA-100]. Adsorption kinetics, adsorption isotherm, separation and desorption of the SIR were also studied.

Poly[[diaqua-mu-4,4 '-bipyridine-dinitratodi-mu-L-tyrosinato-dicopper(II)]: a chiral two-dimensional coordination polymer

The title compound, [Cu-2(C9H10NO3)(2)(NO3)(2)(C10H8N2)-(H2O)(2)](n), contains Cu-II atoms and L-tyrosinate (L-tyr) and 4,4'-bipyridine (4,4'-bipy) ligands in a 2:2:1 ratio. Each Cu atom is coordinated by one amino N atom and two carboxylate O atoms from two L-tyr ligands, one N atom from a 4,4'-bipy ligand, a monodentate nitrate ion and a water molecule in an elongated octahedral geometry. Adjacent Cu atoms are bridged by the bidentate carboxylate groups into a chain. These chains are further linked by the bridging 4,4'-bipy ligands, forming an undulated chiral two-dimensional sheet. O-H center dot center dot center dot O and N-H center dot center dot center dot O hydrogen bonds connect the sheets in the [100] direction. This study offers useful information for the engineering of chiral coordination polymers with amino acids and 4,4'-bipy ligands by considering the ratios of the metal ion and organic components.

Carbon dioxide/propylene oxide coupling reaction catalyzed by chromium salen complexes

A series of chromium/Schiff base complexes N,N'-bis(salicylidene)-1,2-phenylenediamino chromium(III) X were prepared and employed for the alternating copolymerization of carbon dioxide with racemic propylene oxide in the presence of (4-dimethylamino)pyridine. The effect of the complex structure and reaction conditions on the catalytic activity, the poly(propylene carbonate)/cyclic carbonate (PPC/PC) selectivity, and the polymer head-to-tail linkages was examined. The experiments indicated that N,N'-bis(3,5-di-tert-butylsalicylidene)-1,2-phenylenediamino chromium(III) (NO3) exhibited the highest PPC/PC selectivity as well as polymer head-to-tail linkages and N,N'-bis(3,5-dichlorosalicylidene)-1,2-phenylenediimino chromiu(III) (NO3) possessed the highest catalytic activity among these chromium/Schiff base complexes. The structure of the produced copolymer was characterized by the IR, H-1 NMR, and C-13 NMR measurements.

Spindle-like Lanthanide Orthovanadate Nanoparticles: Facile Synthesis by Ultrasonic Irradiation, Characterization, and Luminescent Properties

A general and facile ultrasonic irradiation method has been established for the synthesis of the lanthanide orthovanadate LnVO(4) (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) nanoparticles from an aqueous solution of Ln(NO3)(3) and NH4VO3 without any surfactant or template. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and photoluminescence (PL) spectra as well as kinetic decays were employed to characterize the as-prepared products. Ultrasonic irradiation has a strong effect on the morphology of the LnVO(4) nanoparticles. The SEM and TEEM images illustrate that the as-formed LnVO(4) particles have a spindle-like shape with an equatorial diameter of 30-70 nm and a length of 100-200 am, which are the aggregates of even.

Alternating copolymerization of carbon dioxide and propylene oxide by single-component cobalt salen complexes with various axial group

A series of single-component cobalt salen complexes, N,N'-bis(salicylidene)-1,2phenylenediamino cobaltIII X(X = Cl (1a), Br (1b), NO3 (1c), CF3COO (1d), BF4 (le), and N3 (If)) (SalphCoX), were prepared for alternating copolymerization of carbon dioxide and propylene oxide(PO) under mild condition. The axial anion X group of the SalenphCoX played important role in tailoring the catalytic activity, polymeric/cyclic carbonate selectivity, as well as stereochemistry of carbonate unit sequence in the polymer chain. SalenphCoX with an electron-withdrawing axial X group (complex 1c) was an ideal catalyst for the copolymerization of CO2 and PO to selectively produce polycarbonate with similar to 99% carbonate linkage and over 81% head-to-tail structure.

Highly Uniform Gd(OH)(3) and Gd2O3:Eu3+ Nanotubes: Facile Synthesis and Luminescence Properties

Uniform Gd(OH)(3) nanotubes have been prepared via a simple wet-chemical route at ambient pressure and low temperature, without any catalysts, templates, or substrates, in which Gd(NO3)(3) was used as the gallium source and ammonia as the alkali. SEM and TEM images indicate that the as-obtained Gd(OH)3 entirely consists of uniform nanotubes in high yield with diameters of about 40 nm and lengths of 200-300 nm. The temperature-dependent morphological evolution and the formation mechanism of the Gd(OH)(3) nanotubes were investigated in detail. Furthermore, the Gd2O3 and Eu3+-doped Gd2O3 nanotubes, which inherit their parents' morphology, were obtained during a direct annealing process in air. The corresponding Gd2O3:Eu3+ nanotubes exhibit the strong red emission corresponding to the D-5(0)-F-7(2), transition of the Eu3+ ions under UV light or low-voltage electron beam excitation, which might find potential applications in the fields such as light-emitting phosphors, advanced flat panel displays, or biological labeling.

Facile Surfactant- and Template-Free Synthesis and Luminescent Properties of One-Dimensional Lu2O3:Eu3+ Phosphors

Uniform Lu2O3:Eu3+ nanorods and nanowires have been successfully prepared through a simple solution-based hydrothermal process followed by a subsequent calcination process without using any surfactant, catalyst, or template. On the basis of X-ray diffraction, thermogravimetric analysis and differential scanning calorimetry, and Fourier transform infrared spectroscopy results, it can be assumed that the as-obtained precursors have the structure formula of Lu4O(OH)(9)(NO3), which is a new phase and has not been reported. The morphology of the precursors could be modulated from nanorods to nanowires with the increase of pH value using ammonia solution. The as-formed precursors could transform to cubic Lu2O3:Eu3+ with the same morphology and a slight shrinkage in size after an annealing process, Both the Lu2O3:Eu3+ nanorods and nanowires exhibit the strong red emission corresponding to the D-5(0)-F-7(2) transition of the Eu3+ ions under UV light excitation or low-voltage electron beam excitation.

3D 异金属Bi(III)-Pr(III)配位聚合物的合成、晶体结构和热稳定性

在水溶液中合成了双金属配位聚合物({[(NO3)(H2O)3Pr(μ4-Hedta)Bi-(NO3)2].2H2O}2)n,并通过元素分析、红外光谱和X射线单晶衍射等手段进行了表征.该配合物为单斜晶系,P2(1)/n空间群,a=1.26831(18)nm,b=0.82189(12)nm,c=2.3755(3)nm,β=105.055(2)°,R=0.0429,V=2.3913(6)nm3,Z=4.Bi(Ⅲ)-Pr(Ⅲ)间通过配阴离子Hedta3-中4个羧基的桥联作用构建配合物的3D结构.TG-DSC结果表明,该配合物热分解经历脱水、配体分解以及盐分解过程,残余物为Bi-Pr-O的三元复合氧化物.

离子液基体系Cyanex923(925)/[C_8mim][PF_6]和TBP/[A336][NO_3]萃取钪的研究

对Cyanex923(925)/[C8mim][PF6]和TBP/[A336][NO3]两个离子液基体系在萃取Sc(Ⅲ)中的应用进行了研究。实验表明,由于空间位阻较小,Cyanex923在[C8mim][PF6]中对Sc(Ⅲ)的萃取能力明显优于Cyanex925。温度对Cyanex923/[C8mim][PF6]体系萃取Sc(Ⅲ)的影响较小。与[C8mim][PF6]相反,[A336][NO3]在水中的浓度随酸度增加逐步减少。TBP/[A336][NO3]对Sc(Ⅲ)具有较高的萃取率。