3,5-二甲基吡唑的硝化抑制效果

本文采用室内培养、盆栽和田间试验相结合的方法，对3,5-二甲基吡唑的硝化抑制效果进行了初步探讨。结果表明，3,5-二甲基吡唑（DMP）的施用可以显著抑制土壤硝化作用的进行，其抑制效果受其本身用量及氮素用量的影响显著。但在常规氮施用量下，占纯氮量1.0%的DMP即可以起到显著的硝化抑制效果。在等N量和等抑制剂用量下，DMP的抑制效果显著优于双氰胺，而与3,4-二甲基吡唑磷酸盐效果相当。 对与氮转化有关的土壤酶活性影响结果表明，DMP只在施用后1～2天内对土壤脲酶活性具有短暂的抑制作用，但可较长时间显著抑制土壤硝酸还原酶活性，提高土壤亚硝酸还原酶活性。由于DMP的施用对土壤或肥料氮转化的有效调控，促进了作物对氮素的吸收累积，在生育期较长的水稻上效果更加显著。与对照相比，氮肥表观利用率提高了12.51%，水稻籽粒粗蛋白含量提高了6.24%。同时由于DMP的施用使土壤硝氮累积量显著降低，因此，土壤酸化程度及硝酸盐向土体下层的淋移趋势明显减缓。 对DMP施用后土壤微生物群落动态及微生物活性的研究结果表明，适量DMP的施用不会对表征土壤环境质量变化的土壤生物化学特性产生负面影响，而是通过专性抑制土壤氨氧化菌群落的增殖来实现其硝化抑制作用的，且对参与土壤氮素转化的亚硝酸氧化细菌和反硝化细菌影响很小。因此，DMP将是未来一种具有一定发展前景的土壤硝化作用的专一性抑制剂。

1-羟甲基-3,5-二甲基吡唑(DMHMP)的硝化抑制效应初探

采用室内好气培养方法,以DCD为参比对象研究了新型硝化抑制剂1-羟甲基-3,5-二甲基吡唑(DMHMP)对土壤硝化作用的影响。研究结果表明,DMHMP同DCD一样对土壤硝化作用有明显的抑制效应,主要表现在三个方面:(1)可使土壤NH4+-N含量在整个培养期内显著高于不添加抑制剂的对照处理(P<0.01);(2)使土壤NO3--N含量显著低于对照处理(P<0.01);(3)添加硝化抑制剂处理土壤的pH下降幅度和速度均较对照处理有所降低.当添加DMHMP的量与DCD相等时,其硝化抑制作用不如DCD,而当其添加量为DCD的2倍时,其硝化抑制效果明显优于DCD.在培养的第7天至第21天之间,DMHMP具有最优的硝化抑制效应。

3,5-二甲基吡唑对尿素氮转化及NO_3~--N淋溶的影响

采用室内培养和田间试验相结合的方法,探讨了新型硝化抑制剂3,5-二甲基吡唑(DMP)对尿素氮转化及玉米田硝酸盐淋溶损失的影响.结果表明,DMP对尿素水解仅起短暂的抑制作用,但可在较长时间内显著抑制土壤铵的氧化,且随DMP用量的增加,抑制效应显著增强.培养第10 d时,DMP各处理(0.002 5、0.01及0.025 g/kg)的土壤NH4+-N累积量分别比CK提高了5.17、9.36和11.04倍,而NO3--N累积量于培养第14 d时差异最大,与CK相比分别降低了33.30%、61.19%和73.72%(p<0.01).土壤NO2--N只在尿素施用前期有少量累积,但第3 d DMP各处理土壤NO2--N含量降低幅度达95.77%~96.13%;土壤矿质氮总量于10 d以后,随DMP用量的增加,显著降低,而DMP1处理的土壤微生物量N在培养14~56 d期间显著提高.连续2 a的玉米田间试验原位取土测定结果表明,2004和2005年,DMP的施用使作物根系密集层以下(40~100 cm)土层的NO3--N累积总量分别比CK降低了28.77%和44.70%.因此,硝化抑制剂DMP与尿素配合施用是调控氮素转化、缓解氮肥污染的有效措施.

3,5-二甲基吡唑磷酸盐(DMPZP)对土壤硝化作用的影响

采用好气培养法,以双氰胺(DCD)为参比对象研究了新型吡唑类硝化抑制剂3,5-二甲基吡唑磷酸盐(DMPZP)对土壤硝化作用的影响.结果表明,DMPZP对土壤中的铵氧化作用有较强的抑制效果,在施用量为1.0%(纯N含量)时能显著提高土壤中的NH4+-N浓度,降低NO3--N浓度.DMPZP的硝化抑制效应随用量的增加而增强,相同质量的DMPZP的硝化抑制效果不及DCD,而DCD又不及2倍质量的DMPZP,但等摩尔数(物质量)的DMPZP硝化抑制效果明显优于DCD.DMPZP在施用后的第7天至第14天的硝化抑制作用最强,与不添加抑制剂的处理相比,DMPZP添加量为1.0%和2.0%(纯N含量)时的表观硝化率在第7天和第14天分别降低了29.3%、41.7%和18.6%、34.3%;在此期间,添加DMPZP处理的硝化抑制率均高于30%.DMPZP的施用还可减缓土壤pH的降低速率,但施用DMPZP和DCD对土壤pH的影响差异不显著.

邻苯二酚2,3-双加氧酶基因克隆、定位和高效表达

采用特异性引物 ,以菲、芘降解菌株ZL5的代谢性质粒为模板 ,扩增出邻苯二酚 2 ,3-双加氧酶 (C2 3O)基因 .将该基因和表达载体pET - 30a(+)连接 ,转化E .coliJM10 9(DE3) ,获得了高效表达的转化子 .SDS -PAGE结果表明 ,转化子的C2 3O蛋白不仅在细胞内存在 ,而且能被分泌到胞外 ,薄层扫描显示 ,转化子细胞内和细胞外表达蛋白总量占细胞总蛋白的 4 2 % .酶活分析表明 ,分布在转化子细胞内、外的表达蛋白都具有较高的C2 3O比活力 .Southern杂交将菌株ZL5的C2 3O基因定位在内生质粒的不同酶切片段上 .图 5表 1参 12

Ring-Enlargement of Dimethylaminopropenoyl Cyclopropanes: An Efficient Route to Substituted 2,3-Dihydrofurans

A convenient and efficient synthesis of substituted dihydrofurans is developed via ring-enlargement of 1-dimethylaminopropenoyl-1-carbamoyl/benzoyl cycloproparres catalyzed by ammonium acetate in acetic acid with high regio- and stereoselectivity. Some of the newly synthesized substituted dihydrofurans are subjected to further synthetic transformation in the presence of NaOH (aq) in ethanol to afford the corresponding 5-aryl-2,3-dihydrofuro[3,2-c]pyfidin-4(5H)-ones in high yields.

Preparation and characterization of poly(piperazineamide) composite nanofiltration membrane by interfacial polymerization of 3,3 ',5,5 '-biphenyl tetraacyl chloride and piperazine

Most nanofiltration (NF) membranes are composite and have a polyamide thin film prepared by interfacial polymerization. Their performances mainly correlate the structure of the thin film and monomers used for its preparation. In this work, a novel thin-film composite (TFC) nanofiltration membrane was successfully prepared from 3,3',5,5'-biphenyl tetraacyl chloride (mm-BTEC) and piperazine (PIP) through interfacial polymerization. Attenuated reflectance infrared (ATR-IR) and X-ray photoelectronic spectroscopy (XPS) were used to characterize the chemical composition of the membrane surface. The membrane performance was optimized by studying preparation parameters including monomer concentration, reaction time, and pH of aqueous phase.

Investigation of 3,3 ',5,5 '-tetramethylbenzidine as colorimetric substrate for a peroxidatic DNAzyme

in this Work, the suitability of 3,3',5,5'-tetramethylbenzidine sulfate (TMB) as the substrate of a DNAzyme catalytic system composed of a guanine-quadruplex DNA molecule and hemin was investigated. In the presence of H2O2, the hemin-DNA complex catalyzes the oxidation of TMB to produce two colored products, much like a peroxidase. The color-generating activity of this system could be influenced by several factors such as buffer type, pH value, DNA sequence, reaction time, and concentrations of both the hemin and H2O2. To illustrate the utility of this catalytic system, we designed a colorimetric assay, in which a synthetic oligonucleotide with a sequence complementary to the G-quadruplex DNA was used as the target. A detection limit of 1.86 nM was obtained. Our data have shown that TMB was an excellent colorimetric indicator that reported the peoxidase activities of the widely studied hemin-G-quadruplex DNAzyme system.

Facile shape-controlled synthesis of luminescent europium benzene-1,3,5-tricarboxylate architectures at room temperature

The large-scale synthesis of the metal-organic framework Eu(1,3,5-BTC)center dot 6H(2)O nanocrystallites with delicate morphologies such as sheaflike, butterflylike, and flowerlike superstructures composed of nanowires have been realized via a simple solution phase method at room temperature. Time-dependent experiments indicate that these superstructures were constructed by the splitting crystal growth mechanism, as has been noted in some minerals in nature. The synthetic parameters such as reaction time, concentration and molar ratio of reactants, surfactant, and reaction temperature all affected the morphology of the Eu(1,3,5-BTC)center dot 6H(2)O architectures. These well-arranged architectures exhibit red emission corresponding to the D-5(0) -> F-7(2) transition of the Eu3+ ions under UV light excitation, and the lifetime is determined to be about 0.22 ms.

Coordination-Induced Formation of One-Dimensional Nanostructures of Europium Benzene-1,3,5-tricarboxylate and Its Solid-State Thermal Transformation

Novel one-dimensional europium benzene-1,3,5-tricarboxylate compressed nanorods have been synthesized oil it large scale through direct precipitation in solution phase under moderate conditions without the assistance of any surfactant, catalyst, or template. The obtained nanorods have widths of about 50-100 not, thicknesses of 10-20 nm, and lengths ranging from a few hundred nanometers to several micrometers. X-ray powder diffraction. elemental analysis, Fourier transform infrared Studies, and thermogravimetric and differential thermal analysis show that the nanorods have the structural formula of Eu(1,3,5-BTC)center dot 6H(2)O. Upon UV excitation, these nanorods exhibit a highly efficient luminescence. which comes from the Eu3+ ions. Moreover, Eu2O3 nanorods Could also be obtained via a thermal decomposition method using the corresponding complex as a precursor. This synthetic route is promising for the preparation of other one-dimensional crystalline nanomaterials because of its simplicity and the low cost of the starting reagents.

New process for the preparation of 3,5-dihydroxy-1-pentylbenzene

A new process for the preparation of 3,5-dihydroxy-1-pentylbenzene, which is used as medicinal intermediate and raw material for the synthesis of HIV restrainer, is proposed in this paper. Technical 3,5-dimethoxybenzoic acid reacted with lithium hydride to form a salt (I) which acylated n-butyllithium directly to give 1-(3,5-dimethoxyphenyl)-1-pentanone (II) in 85.06% yield. Then (II) was reduced through a Wolff-K-Huangminglong reaction at 210 degrees C to give 3,5-dimethoxy-1-pentylbenzene (III). Finally, (III) refluxed with melt pyridine hydrochloride at 200 degrees C for 2 h to afford the target product 3,5-dihydroxy-1-pentylbenzene (IV). The total yield of (IV) amounted to 61.50% and its mass percentage was 98.22%. The products were characterized by means of IR, H-1-NMR, GC and HLPC-MS. The results indicated that this synthetic route was feasible, characterized by simple process and higher yield, and superior to the published ones.

Polyamide thin film composite membranes prepared from 3,4',5-biphenyl triacyl chloride, 3,3',5,5'-biphenyl tetraacyl chloride and m-phenylenediamine

Two novel of tri- and tetra-functional biphenyl acid chloride: 3,4',5-biphenyl triacyl chloride (BTRC) and 3,3',5,5'-biphenyl tetraacyl chloride (BTEC), were synthesized, and used as new monomers for the preparations of the thin film composite (TFC) reverse osmosis (RO) membranes. The TFC RO membranes were prepared on a polysulfone supporting film through interfacial polymerization with the two new monomers and m-phenylenediamine (MPD). The membranes were characterized for the permeation properties, chemical composition, d-space between polymer chains, hydrophilicity, membrane morphology including top surface and cross-section. Permeation experiment was employed to evaluate the membranes performance including salt rejection and water flux. The surface structure and chemical composition of membranes were analyzed by attenuated total reflectance infrared (ATR-IR) and X-ray photoelectronic spectroscopy (XPS). The results revealed that the active layer of membranes was composed of highly cross-linked aromatic polyamide with the functional acylamide (-CONH-) bonds. The TFC membranes prepared from biphenyl acid chloride exhibit higher salt rejection compared with that prepared from trimesoyl chloride (TMC) at the expanse of some flux.

Efficient synthesis of trimethylsilyl-substituted dithieno[2,3-b:3',2'-d]thiophene,tetra[2,3-thienylene] and hexa[2,3-thienylene] from substituted [3,3']Bithiophenyl

Efficient synthetic procedures for the preparation of beta-trithiophenes (dithieno[2,3-b:3',2'-d]thiophene) and two macrocyclic compounds, tetra[2,3-thienylene] and hexa[2,3-thienylene] bearing trimethylsilyl (TMS) groups from 2,2'-dibromo-5,5'-bistrimethylsilanyl[3,3']bithiophenyl are reported. The UV-Vis spectra property and crystal structures of these macrocyclic oligothiophenes are described.

Crystal structures of EtEDTB center dot 1.4C(2)H(5)OH center dot 5H(2)O and H4EtEDTB(ClO4)(4)center dot C2H5OH (EtEDTB=N, N, N ', N '-tetrakis[2-(1-ethylbenzimidazolyl)methyl]-1,2-ethanediamine)

The crystal structures of EtEDTB.1.4C(2)H(5)OH.5H(2)O 1 and H4EtEDTB(ClO4)(4).C2H5OH 2 (EtEDTB = N, N,N',N'-tetrakis[2-(1-ethylbenzimidazolyl)methyl]-1,2-ethanediamine) have been determined by single-crystal X-ray diffraction method. Compound 1 crystallizes in the space group P(1) over bar with a = 11.489(2), b = 11.866(3), c = 12.002(3) Angstrom, alpha = 97.47(2), beta = 114.564(13), gamma = 114.11(2)degrees, V = 1266.6(5) Angstrom(3), Z = 1, M-r = 847.48, D-c = 1.111 g/cm(3), F(000) = 456 and mu(MoKalpha) = 0.076 mm(-1). A total of 5207 reflections were measured for 1, of which 4323 were independent. The structure of 1 was solved by direct methods and refined by full-matrix least-squares technique to the final R = 0.0706 and wR = 0.1802 for 1318 observed reflections with I > 2sigma(I). In the structure of 1, centrosymmetric EtEDTB molecules are linked by hydrogen bonds through water and ethanol to form 2-dimensional network. Compound 2 crystallizes in the space group C2/c with a = 24.260(5), b = 13.040(3), c = 17.680(4) Angstrom, beta = 97.50(3)degrees, V = 5545.2(2) Angstrom(3), Z = 4, M-r = 1140.80, D-c = 1.366 g/cm(3), F(000) = 2384 and mu(MoKalpha) = 0.289 mm(-1).