Effects of Different Nitrogen Application Methods on Enzyme Activities in Leaves at Late Growth Stage of Spring Maize

[Objective] This paper aimed at exploring the effects of different nitrogen application methods on the enzyme activities of leaves at ear position in late growth stage of maize. [Method] By pot experiment, the superoxide dismutase （SOD） activity, peroxidase （POD） activity, malonyl dialdehyde （MDA） content and soluble protein content were determined. [Result] At the filling stage and ripening stage, with the increasing of nitrogen application rate, MDA content gradually decreased, while SOD activity, POD activity and soluble protein content increased. MDA content with two topdressing nitrogen was lower than that with one top dressing nitrogen at the same nitrogen application rate, while SOD activity, POD activity and soluble protein content with two topdressing nitrogen were higher than that with one topdressing nitrogen. [Conclusion] Different nitrogen application methods have relatively significant effects on the MDA content, SOD activity, POD activity and soluble protein content, which is of certain directive significance for preventing spring maize prematuration.

Leaching and Transformation of Nitrogen Fertilizers in Soil After Application of N with Irrigation: A Soil Column Method

A soil column method was used to compare the effect of drip fertigation (the application of fertilizer through drip irrigation systems, DFI) on the leaching loss and transformation of urea-N in soil with that of surface fertilization combined with flood irrigation (SFI), and to study the leaching loss and transformation of three kinds of nitrogen fertilizers (nitrate fertilizer, ammonium fertilizer, and urea fertilizer) in two contrasting soils after the fertigation. In comparison to SFI, DFI decreased leaching loss of urea-N from the soil and increased the mineral N (NH4+-N + NO3- -N) in the soil. The N leached from a clay loam soil ranged from 5.7% to 9.6% of the total N added as fertilizer, whereas for a sandy loam soil they ranged between 16.2% and 30.4%. Leaching losses of mineral N were higher when nitrate fertilizer was used compared to urea or ammonium fertilizer. Compared to the control (without urea addition), on the first day when soils were fertigated with urea, there were increases in NH4+-N in the soils. This confirmed the rapid hydrolysis of urea in soil during fertigation. NH4+-N in soils reached a peak about 5 days after fertigation, and due to nitrification it began to decrease at day 10. After applying NH4+-N fertilizer and urea and during the incubation period, the mineral nitrogen in the soil decreased. This may be related to the occurrence of NH4+-N fixation or volatilization in the soil during the fertigation process.

Effect of drip irrigation method, nitrogen source, and flushing schedule on emitter clogging

Field experiments were carried out at the National Research Center farm, Nubaria area, Behura Governorate, Egypt, to study the effect of nitrogen source, flushing schedule and irrigation method on emitter clogging. Peanut Giza 5 variety (Arachishy pogaea L.) was planted in sandy soil during two successive growing seasons (2010-2011) in the 1st week of May and harvested after 130 days. Treatments used are: 1) two irrigation methods: surface drip irrigation and sub-surface drip irrigation (SDI;SSDI), 2) nitrogen source (NS):NH4NO3, (NH4)2SO4 and Ca(NO3)2 (NS1, NS2 and NS3) and 3) flushing number (FL) 0, 1 and 4 (FL1, FL2;FL3). The experiments design was split-split plot and three replicates were used. Data obtained were subjected to statistical analysis. The main effects of treatments used on clogging per cent could be written the following ascending orders: SDI 3 2 1, NS1 2 3. Concerning the 1st interaction the following ascending orders denote their effects on clogging percent: SDI × FL3 2 1, SDI × NS1 2 3, SSDI × FL3 2 1, SSDI × NS1 2 3, FL1 × NS1 1 × NS2 1 × NS3, FL2 × NS1 2 × NS2 2 × NS3 and FL3 × NS1 3 × NS2 3 × NS3. The differences between any two treatments and/or any two interactions in clogging percent were significant at the 5% level. The effect of the 2nd interaction on clogging percent was significant at the 5% level. The maximum value of clogging (20.18%) and the lowest one (3.9%) were archived in the interactions: SSDI × FL1 × NS3 and SDI × FL3 × NS1, respectively.

Effects of Tillage Methods on Soil Organic Carbon and Total Nitrogen Content in the Loess Plateau

In order to determine whether long-term no-tillage operation in the loess plateau threatens soil fertility and crop yield,a suitable high-yield and efficient tillage technology system was established.In the Changwu loess plateau agri-Gecological experiment station of the Northwest A&F University of Changwu County,Shaanxi Province,the no-tillage experimental field for three consecutive years was selected.In September 2015,no-tillage,tillage,and rotary tillage were carried out before winter wheat was sowed.After the harvest of winter wheat in2016,soil organic carbon,total nitrogen and wheat yield in 0-30 cm soil layers under different tillage methods were analyzed.The results showed that the soil organic carbon and total nitrogen contents in the 0-30 cm soil layer decreased along the profile under the three tillage methods.In this study,the soil organic carbon and total nitrogen content in the 0-10 cm soil layer under different tillage methods were no-tillage>rotary tillage>tillage,the actual yield of winter yield in one hectare was tillage>rotary tillage>no-tillage,and there was significant difference in the actual yield of winter wheat only between the no-tillage and tillage.

Effect of nitrogen introduction methods on the microstructure and properties of gradient cemented carbides

Gradient cemented carbides with the surface depleted in cubic phases were prepared following normal powder metallurgical pro-cedures.Gradient zone formation and the influence of nitrogen introduction methods on the microstructure and performance of the alloys were investigated.The results show that the simple one-step vacuum sintering technique is doable for producing gradient cemented carbides.Gradient structure formation is attributed to the gradient in nitrogen activity during sintering,but is independent from nitrogen introduced methods.A uniform carbon distribution is found throughout the materials.Moreover,the transverse rupture strength of the cemented carbides can be increased by a gradient layer.Different nitrogen carriers give the alloys distinguishing microstructure and mechanical properties,and a gradient alloy with ultrafine-TiC0.5N0.5 is found optimal.

Deconvolution Method for Determination of the Nitrogen Content in Cellulose Carbamates

Cellulose carbamates (CC) were synthesized with microcrystalline cellulose as raw materials. The Fourier transform infrared spectra of CC with different nitrogen content were recorded. The accurate results of the nitrogen content for CC can be obtained by using the deconvolution method when the nitrogen content is less than 3.5%. The relationship between the nitrogen content and the absorption intensity ratio of the corresponding separated absorption peaks in FTIR spectra has been expressed bg an equation precisely.

Modified Conway Method for soil available nitrogen testing

The ideal reducing reagent in testing available nitrogen of soil by Conway Methodis Devard‘s alloy.The optimum ratio of soil:Devard’s alloy:1.0N NaOH solution is 5.0g:0.2g:5ml.When reaction goes on at 30℃ for 4 hours,the rate of soil NO3-N reduction is about 90%,and the recovery rate of soil NH4-N is about 95%.Some organic nitrogen can be measured at thesame time.This method is defined as the Modified Conway Method and the soil N-min is r=0.982（n=10）.In predicting soil nitrogen supplying power,the Modified Conway Method takesonly 1/6 of time needed by Conway Method.The Modified Conway Method can also be used forthe measure of soil N-min.

Synthesis of large diamond crystals containing high-nitrogen concentration at high pressure and high temperature using Ni-based solvent by temperature gradient method

This paper reprots that with Ni-based catalyst/solvent and with a dopant of NAN3, large green single crystal diamonds with perfect shape are successfully synthesized by temperature gradient method under high pressure and high temperature in a China-type cubic anvil high-pressure apparatus （SPD-6 × 1200）, and the highest nitrogen concentration reaches approximately 121-1257 ppm calculated by infrared absorption spectra. The synthesis conditions are about 5.5 CPa and 1240-1300 ℃. The growth behaviour of diamond with high-nitrogen concentration is investigated in detail. The results show that, with increasing the content of NaN3 added in synthesis system, the width of synthesis temperature region for growth high-quality diamonds becomes narrower, and the morphology of diamond crystal is changed from cube-octahedral to octahedral at same temperature and pressure, the crystal growth rate is slowed down, nevertheless, the nitrogen concentration doped in synthetic diamond increases.

A NEW FACILE METHOD FOR THE SYNTHESIS OF AZACROWN ETHERS BY USING BENZYLSULFONAMIDE AS A SOURCE OF NITROGEN

Benzylsulfonamide was used as a source of nitrogen in the syn- thesis of azacrown ethers,and the cyclic intermediates were easily deben- zylsulfonylated by treating with CaF_2/H_2SO_4 to afford the azacrown ethers.

Effects of dense planting patterns on photosynthetic traits of different vertical layers and yield of wheat under different nitrogen rates

A two-year field experiment was conducted to measure the effects of densification methods on photosynthesis and yield of densely planted wheat.Inter-plant and inter-row distances were used to define ratefixed pattern(RR)and row-fixed pattern(RS)density treatments.Meanwhile,four nitrogen(N)rates(0,144,192,and 240 kg N ha-1,termed N0,N144,N192,and N240)were applied with three densities(225,292.5,and 360×10^(4)plants ha^(-1),termed D225,D292.5,and D360).The wheat canopy was clipped into three equal vertical layers(top,middle,and bottom layers),and their chlorophyll density(Ch D)and photosynthetically active radiation interception(FIPAR)were measured.Results showed that the response of Ch D and FIPAR to N rate,density,and pattern varied with different layers.N rate,density,and pattern had significant interaction effects on Ch D.The maximum values of whole-canopy Ch D in the two seasons appeared in N240 combined with D292.5 and D360 under RR,respectively.Across two growing seasons,FIPAR values of RR were higher than those of RS by 29.37%for the top layer and 5.68%for the middle layer,while lower than those of RS by 20.62%for the bottom layer on average.With a low N supply(N0),grain yield was not significantly affected by density for both patterns.At N240,increasing density significantly increased yield under RR,but D360 of RS significantly decreased yield by 3.72%and 9.00%versus D225 in two seasons,respectively.With an appropriate and sufficient N application,RR increased the yield of densely planted wheat more than RS.Additionally,the maximum yield in two seasons appeared in the combination of D360 with N144 or N192 rather than of D225 with N240 under both patterns,suggesting that dense planting combined with an appropriate N-reduction application is feasible to increase photosynthesis capacity and yield.

Structural regulation strategies of nitrogen reduction electrocatalysts

Ammonia is a carrier of high energy density and a good hydrogen storage substance.The Haber-Bosch process accounts for 90%of the world's ammonia production,which relies on natural gas and fossil resources as energy sources,not only polluting the ecological environment,but also accelerating the consumption of resources.To explore new ways to synthesize ammonia and reduce carbon emissions,electrocatalytic nitrogen reduction reaction(NRR)to produce ammonia has been emerged owing to the advantages of environmental protection,low energy consumption and mild reaction conditions.Here,we systematize the NRR mechanisms,including dissociation mechanism,association mechanism(involving distal pathway,alternative path,and enzymatic mechanism),and Mars-van Krevelen mechanism.Then,theoretical calculations,performance parameters,synthesis methods,and types of NRR electrocatalysts are introduced in detail.Moreover,effective strategies to optimize the electronic structures of NRR electrocatalysts are emphatically discussed,including d-band center modulation(involving monoatomic dispersion,doping strategy,defect engineering,interface engineering,and strain effect),p-band center modulation,and other regulation strategies(involving construction of heterojunction,electron spin state modulation,phase interface engineering,and lithium ion mediation).Furthermore,we introduce NRR-related cell design and development.In addition,we evaluate relevant NRR experimental techniques,including N adsorption characterization techniques and methods for identification of active sites.Finally,the future challenges and opportunities concerning the improvement of NRR catalysts are outlined.

Numerical Predictions of Laminar Forced Convection Heat Transfer with and without Buoyancy Effects from an Isothermal Horizontal Flat Plate to Supercritical Nitrogen

Numerical predictions are made for Laminar Forced convection heat transfer with and without buoyancy effects for Supercritical Nitrogen flowing over an isothermal horizontal flat plate with a heated surface facing downwards.Computations are performed by varying the value ofΔT from5 to 30 K and P_(∞)/P_(cr)ratio from1.1 to 1.5.Variation of all the thermophysical properties of supercritical Nitrogen is considered.The wall temperatures are chosen in such a way that two values of Tw are less than T∗(T*is the temperature at which the fluid has a maximum value of Cp for the given pressure),one value equal to T∗and two values greater than T∗.Three different values of U∞are used to obtain Re∞range of 3.6×10_(4)to 4.74×10^(5)for forced convection without buoyancy effects and Gr_(∞)/Re^(2)_(∞)range of 0.011 to 3.107 for the case where buoyancy effects are predominant.Six different forms of correlations are proposed based on numerical predictions and are compared with actual numerical predictions.It has been found that in all six forms of correlations,the maximum deviations are found to occur in those cases where the pseudocritical temperature TT∗lies between the wall temperature and bulk fluid temperature.

倒置A^(2)/O+A生化法+膜法+磁混凝法污水处理工程实例

采用“倒置A^(2)/O+A生化法+膜法+磁混凝物化法”组合工艺处理污水,分析了工艺特点,并详述了主要构筑物及设备参数。该组合工艺处理效果优良,除磷脱氮效果好,出水COD、TP、NH_(3)-N、TN月均值分别为28、0.2、0.3、6.06mg/L,达到了DB32/1072—2018《太湖地区城镇污水处理厂及重点工业行业主要水污染物排放限值》其他区域污染物排放标准,其中COD、TP和NH_(3)-N三个指标达到了GB3838—2002《地表水环境质量标准》Ⅳ类水排放标准。

麦季耕作方式和玉米季氮肥用量对旱地麦-玉两熟区玉米产量和氮素利用的影响

【目的】在旱地麦-玉两熟区,关于麦季耕作方式与玉米季氮肥用量如何共同影响玉米产量及氮素利用效率的综合性研究相对较少。我们运用熵权法和TOPSIS法建立了综合评价模型,评价各处理方案间的差异,为麦-玉两熟区玉米高产高效生产提供理论依据。【方法】2020—2022年,在典型旱地麦-玉两熟区河南省洛阳市孟津区小浪底镇开展二因素裂区田间定位试验,以麦季旋耕(RT)、翻耕(PT)和深松(SS)3种耕作方式为主区,以玉米季基施氮0 kg/hm^(2)(N0)、150 kg/hm^(2)(N150)、210 kg/hm^(2)(N210)和270 kg/hm^(2)(N270)4个氮肥用量为副区,研究不同处理对玉米产量及其构成因素、成熟期地上部干物质和氮素积累量以及氮素利用效率的影响,并使用熵权法和TOPSIS法建模选优。【结果】麦季耕作方式和玉米季氮肥用量及二者互作对玉米产量、产量构成要素、干物质积累量、氮素积累量和氮素利用效率均有显著影响。与RT和PT处理相比,SS处理玉米平均产量分别提高10.4%和7.8%,干物质积累量分别提高12.4%和6.7%,氮肥偏生产力、氮肥农学效率、氮肥贡献率分别提高14.4%和10.3%、77.5%和50.9%、52.7%和34.5%。相同耕作方式下,随着氮肥用量的增加,玉米产量、干物质积累量、氮素积累量、氮肥农学效率和氮肥贡献率均表现为先增加后稳定,而氮肥吸收效率和氮肥偏生产力逐渐降低。与N270处理相比,N210处理玉米产量、干物质积累量、氮素积累量、氮素内在效率和氮肥贡献率在3年中均无显著差异,但氮肥吸收效率、氮肥偏生产力和氮肥农学效率分别显著提高29.2%、30.1%和33.0%。从互作效应看,3年中SSN210处理的产量、干物质积累量和氮素积累量虽与SSN270无显著差异,但均显著高于其他处理,平均增幅分别为10.1%~70.4%、7.0%~59.2%和6.1%~65.3%;氮肥农学效率除2021年低于SSN150处理外,其余年份均显著高于其他处理14.8%~237.9%;3年平均氮肥内在效率和氮肥贡献率也均高于其他处理。运用TOPSIS法进行综合评价后发现,在同一施氮量下3年中综合评价值均表现为SS>PT>RT,在同一耕作方式下均以N210处理显著高于其他氮肥用量处理,互作条件下均以SSN210处理最高。【结论】麦季深松配合玉米季施氮210 kg/hm^(2),是实现旱地麦-玉两熟区玉米高产高效的有效途径。

耕作方式和生物炭用量对冬小麦产量、土壤氮碳的影响

为探讨旋耕和深松条件下生物炭施用量对冬小麦产量和土壤碳氮的影响,探寻冬小麦最佳耕作方式和生物炭施用量组合,2021-2023年通过二因素随机区组试验,设置旋耕和深松两种耕作方式,以及0、4.5和9 t·hm^(-2)三个生物炭施用水平,比较分析了不同处理间冬小麦产量和土壤碳氮的差异。结果表明,耕作方式和生物炭施用量对麦田土壤硝态氮残留量、总碳含量、全氮含量和微生物量碳、氮含量均有显著影响,两者的交互作用对土壤全氮含量和微生物量碳含量的影响分别在2022和2023年均达到显著水平。在0~20 cm土层,与旋耕相比,深松下土壤总碳含量和全氮含量分别提高13.9%和29.5%,同时深松对20~30 cm土层土壤微生物量碳、氮含量均有促进作用,使土壤硝态氮残留量显著降低8.5%。与不施生物炭相比,施用生物炭对0~30 cm土层土壤微生物量碳、氮含量均有促进作用,并减少0~50 cm土层土壤硝态氮残留量,使总碳和全氮含量增加22.4%和6.7%。在2022和2023年,深松下冬小麦产量较旋耕均显著增加,增幅分别为15.8%和12.0%,其中SSB2处理产量均最高。综合分析表明,深松+9 t·hm^(-2)生物炭效果最好,是高产和提高土壤肥力的耕作与生物碳施用组合,可以应用推广。

氮掺杂蓝色荧光碳点探针测定替加环素

构建基于N-CDs为荧光探针的简便、有效且灵敏度高的替加环素(TIGE)荧光检测体系,用于注射用TIGE和人血浆样品中TIGE的定量分析。以一水柠檬酸和L-谷胱甘肽为原料,采用熔融法合成了一种氮掺杂的蓝色荧光碳点(N-CDs),并对其结构和性能进行了详细表征。以N-CDs为荧光探针,进一步探讨N-CDs与TIGE的相互作用和猝灭机制。并用于注射用替加环素和人血浆样品中TIGE的定量分析。当TIGE浓度在0.1~25μg·mL^(-1)范围内时,体系的荧光猝灭效率(F0-F)/F0与替加环素浓度(CTIGE)之间呈良好的线性关系,线性拟合方程为y=0.01923 CTIGE+0.07893,R^(2)=0.993。根据3σ/S计算得出本方法检测TIGE的检测限为0.092μg·mL^(-1)(n=13)。

Nutrient Release Characteristics of Vinyl Chloride-Vinyl acetate Copolymers Coated SlowRelease Nitrogen Fertilizer and Its Effect on Soil Mineral Nitrogen

[Objective] The aim was to explore release characteristics of vinyl chlo- ride-vinyl acetate copolymer controlled-release N fertilizer and the effects on minerat nitrogen in soils. [Method] Vinyl chloride-vinyl acetate copolymer and hydroxyl-modi- fied VCNAc were taken as coating materials to prepare slow release fertilizer. Nutri- ent release characteristics of VC/VAc slow release fertilizer was evaluated by water immersion method and the effects of VC/VAc slow release fertilizer on mineral ni- trogen were researched by pot experiment. [Result] The release periods of VC-VAc controlled-release urea and hydroxyl-modified VC/VAc coated urea were 60 and 50 d, respectively. Furthermore, the content of ammonium nitrogen reached the peak on the 30th d and the content of nitrate nitrogen reached the peak on the 60th d in soils in treatments with VCNAc and hydroxyl-modified VC/VAc; the content of nitrate nitrogen rose again on the 120th d in the treatment with VC/VAc. In terms of wheat yield, different treatments showed insignificant differences and rice yield in the treatment with VCNAc was significantly higher than that in the treatment with hy- droxyl-modified VCNAc （P〈0.05）. [Conclusion] The release days of slow controlled- release fertilizer vary upon pot experiment method and water immersion method. Slow controlled-release fertilizer is not suitable for monoculture, due to long fertilizer efficiency, but multiple cropping would be optimal for its role to be fully exploited.

深部中阶煤孔结构的压汞—液氮联合表征及孔隙分形特征

为研究深部中阶煤的孔隙结构特征与孔隙分形规律,利用压汞法和液氮吸附法对沈阳红阳三矿、开滦林西矿、淮南新集二矿和平顶山平煤六矿等典型深部开采矿区的主采煤层煤样进行了孔径、孔容、比表面积等参数测试,基于Menger海绵模型和FHH模型进行了孔隙分形规律的研究。结果表明:(1)基于压汞法的孔隙结构参数测试中平均孔径31.10~34.70 nm,总孔容0.0483~0.0594 mL/g,总比表面积5.5909~7.6528 m^(2)/g,得出典型深部开采矿区的主采煤层孔隙发育比较接近;孔容分布以大孔孔容占主导,微孔与过渡孔孔容比重相当,中孔的孔容分布相对较小,表明大孔孔隙连通性较好,中孔较为闭塞;比表面积分布以微孔为主,占比达70%以上,而中孔和大孔的比重甚微,可见微孔吸附能力最强,不利于深部煤层瓦斯治理;Menger海绵模型分形维数介于2.6~3之间,表明孔隙形状很不规则,孔隙较为复杂,整体上孔隙表面较为粗糙。(2)基于液氮吸附法测试的有效孔径范围为3~177 nm,总孔容与比表面积不同的矿区差异明显,孔容分布以过渡孔和中孔为主,微孔分布较低,大孔为0,表明利用液氮吸附法对于中孔、过渡孔有很好的表征,而难以表征大孔结构,且微孔的孔隙连通性较差;比表面积分布中主要为过渡孔、微孔和中孔,大孔为0,其中以过渡孔为主,且其吸附能力也较强;FHH模型分形维数介于2.0~2.7,结构较为简单规则。(3)讨论了深部中阶煤孔隙结构差异性,其中压汞法和液氮法的孔隙结构参数(比表面积、孔容)随埋深的增加均呈非线性的凹曲线变化;Menger海绵模型与FHH模型分形维数则随埋深的增加呈凸曲线的变化趋势。

硅胶吸附剂吸附分离柴油中芳烃研究

通过金属离子改性和无机酸改性的方式,制得不同孔径分布的硅胶吸附剂,采用静态吸附法和动态脉冲法,研究吸附剂对柴油中芳烃和烷烃的分离特性。结果表明:硅胶吸附剂对双环芳烃的选择性大于单环芳烃;随着芳烃侧链碳数的增加,吸附剂对芳烃的选择性降低;当存在含硫化合物时,吸附剂对芳烃的选择性几乎不变;当存在含氮化合物时,吸附剂对单环芳烃的选择性降低;在60~170℃内,随着吸附温度的升高,各组分的保留体积减小,吸附脱附速率加快,确定100~140℃为最佳分离温度;随着吸附剂孔径的增大,组分的传质速率增大,吸附剂对组分的分离度减小;改性后,吸附剂的传质性能提高,对芳烃组分的分离度提高。对于吸附剂A,当吸附剂孔径从2.2 nm增加到2.4 nm时,对长侧链烷基苯的选择性提高。