Effect of nitrogen on deposition and field emission properties of boron-doped micro-and nano-crystalline diamond films

In this paper,we report the effect of nitrogen on the deposition and properties of boron doped diamond films synthesized by hot filament chemical vapor deposition.The diamond films consisting of micro-grains(nano-grains) were realized with low(high) boron source flow rate during the growth processes.The transition of micro-grains to nano-grains is speculated to be strongly(weekly) related with the boron(nitrogen) flow rate.The grain size and Raman spectral feature vary insignificantly as a function of the nitrogen introduction at a certain boron flow rate.The variation of electron field emission characteristics dependent on nitrogen is different between microcrystalline and nanocrystalline boron doped diamond samples,which are related to the combined phase composition,boron doping level and texture structure.There is an optimum nitrogen proportion to improve the field emission properties of the boron-doped films.

Effect of Nitrogen on the Degradation of Cypermethrin and Its Metabolite 3-Phenoxybenzoic Acid in Soil

Increasing use of pyrethroid insecticides has resulted in concerns regarding potential effects on human health and ecosystems. Cypermethrin and its metabolite 3-phenoxybenzoic acid(PBA) have exerted adverse biological impacts on the environment;therefore,it is critically important to develop different methods to enhance their degradation. In this study,incubation experiments were conducted using samples of an Aquic Inceptisol supplied with nitrogen(N) in the form of NH4NO3 at different levels to investigate the effect of nitrogen on the degradation of cypermethrin and PBA in soil. The results indicated that appropriate N application can promote the degradation of cypermethrin and PBA in soil. The maximum degradation rates were 80.0% for cypermethrin after 14 days of incubation in the treatment with N at a rate of 122.1 kg ha-1 and 41.0% for PBA after 60 days of incubation in the treatment with N at a rate of 182.7 kg ha-1. The corresponding rates in the treatments without nitrogen were 62.7% for cypermethrin and 27.8% for PBA. However,oversupplying N significantly reduced degradation of these compounds. Enhancement of degradation could be explained by the stimulation of microbial activity after the addition of N. In particular,dehydrogenase activities in the soil generally increased with the addition of N,except in the soil where N was applied at the highest level. The lower degradation rate measured in the treatment with an oversupply of N may be attributed to the microbial metabolism shifts induced by high N.

Synergistic Effects of Nitrogen Amendments and Ethylene on Atmospheric Methane Uptake under a Temperate Old-growth Forest

An increase in atmospheric nitrogen (N) deposition can promote soil acidification, which may increase the release of ethylene (C2H4) under forest floors. Unfortunately, knowledge of whether increasing N deposition and C2H4 releases have synergistic effects on soil methane (CH4) uptake is limited and certainly deserves to be examined. We conducted some field measurements and laboratory experiments to examine this issue. The addition of (NH4)2SO4 or NH4Cl at a rate of 45 kg N ha-1 yr-1 reduced the soil CH4 uptake under a temperate old-growth forest in northeast China, and there were synergistic effects of N amendments in the presence of C2H4 concentrations equal to atmospheric CH4 concentration on the soil CH4 uptake, particularly in the NH4Cl-treated plots. Effective concentrations of added C2H4 on the soil CH4 uptake were smaller in NH+4 -treated plots than in KNO3-treated plots. The concentration of ca 0.3 μl C2H4 L-1 in the headspace gases reduced by 20% soil atmospheric CH4 uptake in the NH4Cl-treated plots, and this concentration was easily produced in temperate forest topsoils under short-term anoxic conditions. Together with short-term stimulating effects of N amendments and soil acidification on C2H4 production from forest soils, our observations suggest that knowledge of synergistic effects of NH+4 , rather than NO3- , amendments and C2H4 on the in situ soil CH4 uptake is critical for understanding the role of atmospheric N deposition and cycling of C2H4 under forest floors in reducing global atmospheric CH4 uptake by forests. Synergistic functions of NH4+ -N deposition and C2H4 release due to soil acidification in reducing atmospheric CH4 uptake by forests are discussed.

Effects of lanthanum(Ⅲ) on nitrogen metabolism of soybean seedlings under elevated UV-B radiation

The hydroponic culture experiments of soybean bean seedlings were conducted to investigate the effect of lanthanum(La)on nitrogen metabolism under two different levels of elevated UV-B radiation(UV-B,280-320 nm).The whole process of nitrogen metabolism involves uptake and transport of nitrate,nitrate assimilation,ammonium assimilation,amino acid biosynthesis,and protein synthesis. Compared with the control,UV-B radiation with the intensity of low level 0.15 W/m^2 and high level 0.45 W/m^2 significantly affected the whole nitrogen metabolism in soybean seedlings(p<0.05).It restricted uptake and transport of NO_3^-,inhibited activity of some key nitrogen-metabolism-related enzymes,such as:nitrate reductase(NR)to the nitrate reduction,glutamine systhetase(GS)and glutamine synthase(GOGAT)to the ammonia assimilation,while it increased the content of free amino acids and decreased that of soluble protein as well.The damage effect of high level of UV-B radiation on nitrogen metabolism was greater than that of low level. And UV-B radiation promoted the activity of the anti-adversity enzyme glutamate dehydrogenase(GDH),which reduced the toxicity of excess ammonia in plant.After pretreatment with the optimum concentration of La(20 mg/L),La could increase the activity of NR, GS,GOGAT,and GDH,and ammonia assimilation,but decrease nitrate and ammonia accumulation.In conclusion,La could relieve the damage effect of UV-B radiation on plant by regulating nitrogen metabolism process,and its alleviating effect under low level was better than that under the high one.

Study on Removal Effect of Ammonia Nitrogen in Sewage by the Mixed Substrate

Red brick,cement brick and ceramsite were taken as the substrate of constructed wetland,and removal effect of ammonia nitrogen by the mixed substrate under different combination manners and aeration condition was explored. Research results showed that cement brick had the best removal effect on ammonia nitrogen,followed by red brick and ceramsite; aeration was favorable for the removal of ammonia nitrogen by each substrate and the mixed substrate; removal rate sequence of ammonia nitrogen by each mixed substrate was red brick + cement brick > red brick + cement brick + ceramsite > cement brick + ceramsite > red brick + ceramsite; the combination of red brick + cement brick had the best removal effect on ammonia nitrogen in domestic sewage. Comprehensively considering,the mixed substrate of red brick + cement brick has better stability and higher ammonia nitrogen removal rate,and it is suitable as the mixed adsorption substrate of constructed wetland.

Clear felling and burning effects on soil nitrogen transforming bacteria and actinomycetes population in Chittagong University campus, Bangladesh

The effect of forests clear felling and associated burning on the population of soil nitrogen transforming bacteria and actinomycetes are reported at three pair sites of Chittagong University campus, Bangladesh in monsoon tropical climate. Clear felled area or burnt site and 15-21 year mixed plantation of native and exotic species, situated side by side on low hill having Typic Dystrochrepts soil was represented at each pair site. At all the three pair sites, clear felled area or burnt site showed very significantly (p≤0.001) lower population of actinomycetes, Rhizobium, Nitrosomonas, Nitrobacter and ammonifying as well as denitrifying bacteria compared to their adjacent mixed plantation. From environmental consideration, this finding has implication in managing natural ecosystem.

Interference effects on the photoionization cross sections between two neighbouring atoms:nitrogen as an example

Interference effects on the photoionization cross sections between two neighbouring atoms are considered based on the coherent scattering of the ionized electrons by the two nuclei when their separation is less than or comparable to the de Broglie wave length of the ionized electrons.As an example,the single atomic nitrogen ionization cross section and the total cross sections of two nitrogen atoms with coherently added photoionization amplitudes are calculated from the threshold to about 60 A (1 A=0.1 nm) of the photon energy.The photoionization cross sections of atomic nitrogen are obtained by using the close-coupling R-matrix method.In the calculation 19 states are included.The ionization energy of the atomic nitrogen and the photoionization cross sections agree well with the experimental results.Based on the R-matrix results of atomic nitrogen,the interference effects between two neighbouring nitrogen atoms are obtained.It is shown that the interference effects are considerable when electrons are ionized just above the threshold,even for the separations between the two atoms are larger than two times of the bond length of N 2 molecules.Therefore,in hot and dense samples,effects caused by the coherent interference between the neighbours are expected to be observable for the total photoionization cross sections.

A new sulfur-doped source and synergistic effect with nitrogen for carbon dots produced from glucose

The nitrogen and sulfur co-doped carbon dots(N, S-CDs) with increased luminescence were synthesized by a hydrothermal process in one green pot by using glucose, and a new sulfur-doping source of sodium sulfite was developed.The synergistic effect of the N and S groups was well discussed through the structure analysis of Fourier transform infrared spectra and x-ray photoelectron spectra. The surface states of N, S-CDs embody more complicated functional groups, and S element exists as –SSO3, –C–SO3, and SO-42groups due to the introduction of sodium sulfite. The sulfur-containing groups passivate the surface of the CDs, and the relatively high sulfur groups may reduce the non-radiation centers. The fluorescence is affected by the hydroxyl group of the solvent. The quenching of Fe3+ ion to fluorescence and the sensitivity of fluorescence to p H were also investigated.

Biological effects of implantation and penetration of nitrogenion beams on wheat seeds

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玉米大豆间作干物质积累和氮磷吸收利用的边际效应

【目的】研究间作对玉米大豆干物质积累及氮磷吸收利用特性的影响机制,对实现玉米、大豆间作高产高效具有重要指导意义。【方法】试验设玉米单作、大豆单作、玉米大豆间作3种种植方式,分别测定玉米大口期、吐丝期和成熟期的植株氮磷积累量和大豆开花期、结荚期和成熟期的植株氮磷积累量,研究间作对玉米、大豆不同器官干物质积累及氮磷吸收积累特性,明确氮磷吸收利用的边际效应。【结果】与单作相比,间作降低了玉米干物质和氮磷的积累,促进了根系吸收氮向籽粒的分配;降低了大豆干物质积累,尤其对中行的影响大于边行,边行干物质、氮磷积累体现边际效应优势;与单作体系相比,间作使玉米大豆植株茎叶营养器官氮转移量均减少,分别降低22.13%、29.85%,转运氮对玉米籽粒氮的贡献率分别下降5.11%、17.45%,且根系吸收氮对籽粒氮的贡献率均高于转运氮对籽粒氮的贡献率。间作能够有效提高系统氮利用效率,较玉米、大豆单作分别提高2.34%、4.62倍,使系统氮效率较单作大豆提高26.82%,较单作玉米降低10.16%,玉米在系统产量中占主导地位,占系统产量的82.27%,土地当量比(LER)达到1.47,系统产量为13110 kg/hm^(2),较单作玉米下降3.96%。【结论】间作优势主要在于促进根系吸收氮向籽粒的分配,提高氮的利用效率。

An Experimental Observation of the Thermal Effects and NO Emissions during Dissociation and Oxidation of Ammonia in the Presence of a Bundle of Thermocouples in a Vertical Flow Reactor

Ammonia (NH3) dissociation and oxidation in a cylindrical quartz reactor has been experimentally studied for various inlet NH3 concentrations (5%, 10%, and 15%) and reactor temperatures between 700 K and 1000 K. The thermal effects during both NH3 dissociation (endothermic) and oxidation (exothermic) were observed using a bundle of thermocouples positioned along the central axis of the quartz reactor, while the corresponding NH3 conversions and nitrogen oxides emissions were determined by analysing the gas composition of the reactor exit stream. A stronger endothermic effect, as indicated by a greater temperature drop during NH3 dissociation, was observed as the NH3 feed concentration and reactor temperature increased. During NH3 oxidation, a predominantly greater exothermic effect with increasing NH3 feed concentration and reactor temperature was also evident;however, it was apparent that NH3 dissociation occurred near the reactor inlet, preceding the downstream NH3 and H2 oxidation. For both NH3 dissociation and oxidation, NH3 conversion increased with increasing temperature and decreasing initial NH3 concentration. Significant levels of NOX emissions were observed during NH3 oxidation, which increased with increasing temperature. From the experimental results, it is speculated that the stainless-steel in the thermocouple bundle may have catalysed NH3 dissociation and thus changed the reaction chemistry during NH3 oxidation.

早熟甘蓝型油菜不同生育阶段氮素亏缺与补偿效应研究

为探明早熟油菜不同生育阶段氮素亏缺与补偿效应,以赣油105为试验材料,通过盆栽方式,分别于苗期、越冬期、抽薹期、初花期及终花期进行不施氮、后一生育阶段等量和加倍恢复供氮处理试验,分析了不同处理下早熟甘蓝型油菜的产量及其相关性状、干物质量、氮素吸收与利用效率等指标。结果表明:越冬期至抽薹期氮素亏缺对早熟甘蓝型油菜干物质生产积累影响较大,其加倍施氮处理较等量施氮处理下的总干物质量增加了7.71%;越冬前和初花后氮素亏缺对早熟甘蓝型油菜单株籽粒产量影响较小;越冬期缺氮显著降低了早熟油菜的株高和一次有效分枝数,抽薹期缺氮对单株有效角果数影响最大;早熟油菜产量相关性状及干物质量均存在一定的氮素亏缺补偿效应,各指标补偿效应的大小及补偿有效期存在一定的差异;越冬期至抽薹期保证氮素的充分供应对早熟油菜的氮肥吸收利用效率可起到优化的效果。综上,本研究初步确定了早熟甘蓝型油菜越冬期至抽薹期是氮素需求的关键期和敏感期,初花期是氮素补偿的有效关键期。

氮素转化菌群对牛粪好氧堆肥的保氮效果

为探明氮素转化微生物菌群对牛粪好氧堆肥效果的影响,以牛粪和玉米秸秆为原料,以添加自行研制的复合微生物菌群为接种组,以添加同等体积的无菌水为对照组,研究不同处理下堆体温度、pH值、电导率、总氮含量、硝态氮含量、铵态氮含量及种子发芽指数等指标的变化。结果表明:在试验中,按照10 mL·kg^(-1)的比例添加自行研制的微生物菌群进行牛粪好氧堆肥能够使堆肥的最高温度较对照组上升5.8℃,缩短升温延滞期,提前4 d进入高温期(>50℃),且高温期持续的时间延长4 d,加快牛粪堆料的腐熟;同时,能够固定堆料中的氮素,堆肥结束后,接种组的总氮含量较对照组增加8.14%,氨气减排29.02%。

不同秸秆还田方式下黑土玉米田肥料氮素去向

探究不同秸秆还田方式下肥料氮在连续两季作物系统中的去向,为黑土地保护下的氮肥管理提供重要依据。于2020—2021年在吉林梨树开展大田微区试验,设置无秸秆还田(CK)、深翻还田(DTS)、免耕覆盖还田(NTS)3种秸秆还田方式,每种方式下设置2个施氮水平:180 kg·hm^(-2)(N1)和270 kg·hm^(-2)(N2)。结果表明:当季和第二季玉米成熟期植株氮分别有38.0%~46.8%和12.9%~18.6%来源于^(15)N标记氮肥。肥料氮当季平均利用、残留和损失率分别为32.4%~43.9%、32.8%~51.4%和13.2%~32.7%,秸秆覆盖配施适量氮肥(180 kg·hm^(-2))处理下肥料氮当季利用率显著提高29.5%,而秸秆深翻还田则使肥料氮在土壤中的残留率显著增加18.6%。当季施用肥料氮仍有8.5%~14.9%被第二季玉米吸收利用,两季累积利用率达40.9%~58.8%,在高氮(270 kg·hm^(-2))下秸秆深翻还田显著提高肥料氮的第二季利用率及累积利用效率。综上,秸秆覆盖还田配施适量氮肥有利于提高肥料利用效率,而秸秆深翻还田更有利于高施氮量下土壤对肥料氮的保持,增加其被下季作物利用的机会,两者均能显著减少氮的损失。

基于EFDC模型的表面流人工湿地水力性能和净化效果影响因素分析

为探究长宽比、水深和水力负荷对表面流人工湿地水力性能和净化效果的影响及其定量关系,采用EFDC(environmental fluid dynamics Code)模型建立表面流人工湿地水动力-水质耦合模型并对模型进行率定和验证,基于构建的模型设置3因素6水平的全因子模拟试验,通过分析216组试验结果研究湿地长宽比、水深和水力负荷及其交互作用对湿地水力性能和净化效果的影响,进而采用多元非线性回归模型将多因子影响与7个评价指标之间建立定量关系。结果表明:长宽比、水深和水力负荷之间的交互作用对水力性能和净化效果均有显著影响(P<0.05)。构建的参数与评价指标的回归模型说明水力效率、有效容积率和莫里尔离散指数与长宽比呈指数相关,总氮浓度去除率与水深呈指数相关,回归方程的建模决定系数均大于0.9,经试验数据验证的相对误差在20%以下,说明模型是可靠的。研究可为表面流人工湿地设计和运行提供依据。

Effects of NO_x and SO_2 in cathode stream on the performance of PEMFC

The effects of NOx(in a ratio of NO∶NO2=9∶1) and SO2in cathode streamonthe performance of a single proton ex-change membrane fuel cell(PEMFC) were investigated.NOxwith concentrations of 1×10-3%(in volume,the same as fol-lows),1.4×10-2%and 1×10-3%could cause significant detri mental effects on the cell performance.However,nearly com-plete recovery of the cell performance could be observed after NOxwas shut off and purged with clean air.The electrochemicalmeasurements suggested that thei mpacts of NOxresulted mainlyfromthe superposition of the oxygen reduction reaction(ORR),NOand HNO2oxidation reactions,and the increased cathodic i mpedance.Trace SO2with concentrations of 5×10-6%,5×10-3%,2×10-4%and 3.2×10-4%influenced the cell muchseverer,which could be attributed toits strong adsorption onthesurface of Pt atoms.The cell performance could not be completely recovered after purged with clean air and cyclic voltammetry(CV) tests,due to the changes of electrochemical i mpedance spectroscopy(EIS) and electrochemical active surface(EAS) causedby surface state change after SO2exposure.

不同水氮供应对富士苹果品质产量和果园氮排放的影响

【目的】针对黄土高原旱地苹果园灌水施肥利用率低、氮排放污染严重等现状,探讨不同水氮供应对富士苹果品质、产量的影响,以及果园土壤氨挥发和氧化亚氮排放上的差异,为农业合理施加氮肥和用水量提供一定的参考。【方法】于2022年以短枝富士苹果树为材料,以灌水和施氮量为变量,设置5个不同灌水处理:(W5)100%~-90%θ_(田)、(W4)90%~-80%θ_(田)、(W3)80%~-70%θ_(田)、(W2)70%~-60%θ_(田)、(W1)60%~-50%θ_(田),施氮量设置5个处理:N1(150 kg/ha)、N2(300 kg/ha)、N3(450 kg/ha)、N4(600 kg/ha)、N5(750 kg/ha),分析不同处理苹果生理指标、产量性状及土壤氮素排放的变化。【结果】不同施肥灌水处理下苹果新梢生长长度随灌水量和施氮量的增加而增加;施肥后发生了明显的气态氮排放,在施肥后1周内出现挥发速率峰值。氮素添加明显增加了NH_(3)挥发累积量,而灌水量的增加则呈现降低趋势。NH_(3)挥发最大量为W1N5,其整个生育观测收集阶段挥发总量达到了187.07 kg·hm^(-2);N_(2)O排放通量的峰值在施氮后立即出现,会在第3~4 d达到排放速率高峰,氮肥施入量越多,N_(2)O排放损失量越高,施氮量相同的水平下,灌水越少N_(2)O排放越高。W1N5的N_(2)O排放速率达到最高,整个生育观测收集阶段排放总量达到了578.92 g·hm^(-2);不同水氮供应的果实横纵径、单果质量、大果率、可溶性固形物质量分数与酸度、产量之间均呈显著(P<0.05)和极显著(P<0.01)正相关关系。氮素利用率与横径、大果率、可溶性固形物质量分数、产量之间存在显著正相关关系。因此,水氮利用率与果实品质和产量之间关系密切。最高产量在N3水平获得,N5造成苹果小幅度减产,W4N3处理可以维持苹果产量、提高品质、获得更高的水氮利用效率;建立灌溉量(W)、施氮量(N)与苹果产量之间的二次多项式拟合水氮效应方程为:Y=-0.1511N^(2)-1.2403W^(2)-0.0753WN+162.6075N+547.3469W-4.1108×10^(4),理论最高产量对应水氮用量为施氮486.78 kg·hm^(-2),灌水205.87 mm,最高产量54811.49 kg·hm^(-2)。【结论】综合考虑苹果增产、减少气态氮排放、提高水氮利用率的前提和回归方程的拟合情况,推荐灌水水平为(W4)90%~80%θ_(田)、施氮水平为450 kg·hm~2是黄土高原地区苹果最优的处理组合。

不同补料方式对好氧颗粒污泥合成PHA的影响

为提高好氧颗粒污泥(AGS)合成聚羟基脂肪酸酯(PHA)的产量,探究了4种不同补料方式(未补料、好氧0h补料、好氧0.5h补料和好氧1h补料)对AGS合成PHA的影响,同时考察了此过程中AGS的碳氮磷去除效能以及微生物群落结构变化.结果表明,补料能够提高AGS合成PHA的含量,在好氧1h补料时AGS合成PHA的含量最高,为125.06mg/g;同时补料时间会影响AGS的脱氮除磷性能,当补料时间由好氧0h延迟至好氧1h时,AGS的总氮去除率由(87.49±5.49)%降至(67.60±16.24)%,溶解性正磷酸盐(SOP)去除率由(94.08±1.42)%降至(62.91±15.33)%.且不同补料时间条件下,AGS的微生物群落结构变化较大,合成PHA的优势菌群差异较大,在未补料和好氧0h补料条件下,优势菌为既能合成PHA同时能够脱氮或除磷的不动杆菌属(Acinetobacter);在好氧1h补料条件下中,优势菌为能合成PHA的噬氢菌属(Hydrogenophaga)和黄杆菌属(Flavobacterium).

水体与沉积物中氮、硫的还原过程及相互作用机理研究进展

针对日益严峻的氮、硫污染问题,综述了NO_(3)^(-)/SO_(4)^(2-)的同步还原过程,总结了该过程中不同形态氮、硫物质间的相互作用机理。指出今后的研究重点在于:探究NO_(3)^(-)/SO_(4)^(2-)发生同步化学还原的可能性,研究在化学还原条件与生物还原条件共存情况下NO_(3)^(-)/SO_(4)^(2-)的还原路径,以及化学还原与生物还原对NO_(3)^(-)/SO_(4)^(2-)同步还原的贡献及影响;进一步剖析NO_(3)^(-)抑制SO_(4)^(2-)还原作用的过程,明确其抑制机理及可能发生的相互作用;深入研究硫自养反硝化、硫驱动的异化NO_(3)^(-)还原为NH_(4)^(+)(DNRA)和硫酸盐还原厌氧氨氧化(SRAO)等同步脱氮除硫工艺及其耦合关系,不断优化工艺运行条件,为工业化应用奠定基础。