Nitrogen transfer between N_2-fixing plant and non-N_2-fixing plant

The transfer mechanisms. calculating methods and ecological significance of nitrogen transfer between legumes and non-legumes are briefly reviewed. There are three pathways 0f nitrogen transf6r from legumes to neighboring non-legumes: (1) the nitrogen pass in soluble form from the donor legume root into the soil solution, move by diffusion or/and mass flow to the receiver root and be taken up by the latter, (2) nitrogen pass into the soil solution as before, be taken up and transported by mycorrhizal hyphae attached to the receiver roots,(3) if mycorrhizal hyphae form connections (bridges) between the two root systems, the nitrogen could pass into the fungus within the donor root and be transported into the receiver root without ever being in the soil solution. The mechanisms of nitrogen transfer between N2-fixing plants and non-N2-fixing plants are reviewed in terms of indirect and direct pathways. The indirect N-transfer process is related to the release of nitrogen from legumes(donor plants), the possible interaction of this nitrogen with soil, the decomposition and mineralization of legumes and tumover of nitrogen, the nitrogen absorbing and competing abilities of the legume and the non-legume (receiver plant). The direCt nitrogen transfer process is generally considered to be related to the nitrogen gradient and physiological imbalance between legumes and non-legumes, and when the donor legume lies in stressful stage (i.e. removal of shoots or attacked by insects), the nitrogen transfer can be improved significantly. Themethods of deterrnining nitrogen transfer (lndirect 15N-isotope. dilution method and direct 15N determination method) are evaluated, and their advantages and shortcomings are shown in this review.

Room Temperature Phosphorescence pH Switch Based on Photo-induced Electron Transfer

In this paper, photoinduced electron transfer(PET) phosphoroionophore, N-(1-bromo- 2-naphthylmethyl)-diethanolamine (BND) was synthesized and its phosphorescent characteristics were studied. The experimental results showed that strong phosphorescence could be observed in b-cyclodextrin aqueous solution only at low pH value. This system combined AND and NOT function to produce a three-input inhibit (INH) logic gate.

Theoretical Study on the Self, Water-assisted and Au-to-assisted Dimer Proton Transfer Reaction in the N-Hydroxy-Methylen-Formamide

The proton transfer in the isolated, mono and dehydrated forms, isolated dimers of N-Hydroxy Methylen Formamide (NHMF) have been completely investigated in the present study using Density Functional Theory (DFT), M?ller-Plesset perturbation (MP2) and Hartree-Fock (HF) methods with the 6-31G* and 6-311G* basis sets. The barrier heights for both H2O-assisted and auto-assistance reactions are significantly lower than that of the bare tautomerization reaction from NHMF to N-Formyl Formamide (NFF), implying the importance of the superior catalytic effect of H2O in the monomer of NHMF and important role of HOCH= N-COH for the intramolecular proton transfer.

Exploring the effect of aggregation-induced emission on the excited state intramolecular proton transfer for a bis-imine derivative by quantum mechanics and our own n-layered integrated molecular orbital and molecular mechanics calculations

We theoretically investigate the excited state intramolecular proton transfer(ESIPT) behavior of the novel fluorophore bis-imine derivative molecule HNP which was designed based on the intersection of 1-(hydrazonomethyl)-naphthalene-2-ol and 1-pyrenecarboxaldehyde. Especially, the density functional theory(DFT) and time-dependent density functional theory(TDDFT) methods for HNP monomer are introduced. Moreover, the "our own n-layered integrated molecular orbital and molecular mechanics"(ONIOM) method(TDDFT:universal force field(UFF)) is used to reveal the aggregation-induced emission(AIE) effect on the ESIPT process for HNP in crystal. Our results confirm that the ESIPT process happens upon the photoexcitation for the HNP monomer and HNP in crystal, which is distinctly monitored by the optimized geometric structures and the potential energy curves. In addition, the results of potential energy curves reveal that the ESIPT process in HNP will be promoted by the AIE effect. Furthermore, the highest occupied molecular orbital(HOMO) and lowest unoccupied molecular orbital(LUMO) for the HNP monomer and HNP in crystal have been calculated. The calculation demonstrates that the electron density decrease of proton donor caused by excitation promotes the ESIPT process. In addition, we find that the variation of atomic dipole moment corrected Hirshfeld population(ADCH) charge for proton acceptor induced by the AIE effect facilitates the ESIPT process. The results will be expected to deepen the understanding of ESIPT dynamics for luminophore under the AIE effect and provide insight into future design of high-efficient AIE compounds.

N-杂环的催化氧化脱氢的研究进展

由于氢气高质量能量密度(120MJ·kg^(-1))和无碳燃烧产物,其生产正越来越多地与过剩的可再生电力相结合。但是以氢作为储能介质仍然无法大规模利用,主要障碍在于氢不利的元素特性。N-杂环或其他能与氢气结合并在环境条件下储存的化合物,为克服经典的氢气储存加氢和脱氢释放有关的问题提出了一个替代方案。探索一种简单、高效、稳定和绿色的催化体系是实现这一典型转化的关键。总结了过去5年来开发Ru、Ni、Co、Fe和Mn催化剂与n杂环化合物催化氧化脱氢反应所取得的显著进展,期望这一领域的研究结果能够启发其他人进一步制备新型高效、可控和绿色的催化剂,用于氢的借用或氢气转移的应用,从而能够促进在不久的将来建立适合燃料电池的供氢体系。

N掺杂对Si-DLC薄膜的结构性能影响及摩擦机理研究

采用平板阴极等离子体增强化学气相沉积技术,通过调控N_(2)流量在GCr15基底上制备了系列硅氮共掺杂类金刚石碳基(Si/N-DLC)薄膜,分析探索N掺杂对于Si-DLC薄膜结构、力学性能和摩擦学行为的作用规律以及Si/NDLC薄膜的低摩擦磨损机理.结果表明:N元素的引入促进Si-DLC薄膜中sp^(2)-C结构的形成,降低了薄膜的硬度和弹性模量,但能大幅改善Si-DLC薄膜的韧性并增强结合(>20 N).更重要的是,N掺杂可有效降低Si-DLC薄膜的摩擦系数并改善其耐磨性能,摩擦系数和磨损率相较于Si-DLC薄膜分别降低了约26%和45%.其摩擦机理是类石墨碳(GLC)转移膜的形成使得摩擦界面发生转移,有效降低了Si/N-DLC薄膜的摩擦系数,并且依赖于摩擦界面的石墨化程度和氢含量.而磨损行为取决于其薄膜自身韧性和抵抗弹塑性变形的能力,磨痕内部脆性断裂缺口会造成转移膜的大面积破坏,加剧了黏着磨损.此外,确定了Si/N-DLC薄膜低摩擦(摩擦系数≤0.05)的最佳服役区间,相关结果为Si/N-DLC薄膜的结构性能调控和工程应用提供参考.

SERPINE1在胃癌中的表达及对胃癌细胞免疫逃逸和β-catenin/N-cadherin信号通路的作用机制研究

目的 探讨丝氨酸蛋白酶抑制剂E1(SERPINE1)在胃癌中的表达及对胃癌细胞免疫逃逸及β-连环蛋白/神经钙黏蛋白(β-catenin/N-cadherin)信号通路的作用机制。方法 选择2020年1月至2022年1月在定州市人民医院接受胃癌手术的78例患者作为研究对象,收集其胃癌组织及癌旁组织,采用免疫组织化学法检测组织中SERPINE1表达情况。采用人胃癌细胞系SGC-7901细胞,经不同处理后分为对照组(SGC-7901细胞)、oe-SERPINE1组(pcDNA3.1-SERPINE1载体)、oe-NC组(空pcDNA3.1载体)、SERPINE1 siRNA组(SERPINE1 siRNA)及si-NC组(si-NC)。采用实时荧光定量PCR法检测各组细胞中SERPINE1 mRNA的表达水平,采用Transwell法检测各组细胞的侵袭数目,采用划痕实验检测各组细胞的迁移距离,采用蛋白质印迹法检测各组细胞中程序性死亡受体-1(PD-1)、程序性死亡配体-1(PD-L1)、β-catenin、N-cadherin的蛋白表达水平。结果 胃癌组织和癌旁组织中SERPINE1阳性表达率分别为88.46%和19.23%,差异有统计学意义(P<0.05)。oe-NC组细胞的SERPINE1 mRNA表达水平、侵袭数目、迁移距离,以及PD-1、PD-L1、β-catenin、N-cadherin蛋白表达水平与对照组差异均无统计学意义(P均>0.05)。oe-SERPINE1组细胞的上述指标均较oe-NC组显著升高(P均<0.05)。si-NC组细胞的上述指标均较oe-SERPINE1组显著降低(P均<0.05)。SERPINE1siRNA组细胞的上述指标均较si-NC组显著降低(P均<0.05)。结论 SERPINE1在胃癌组织中呈高表达,下调SERPINE1表达可显著抑制胃癌细胞的侵袭和迁移,抑制PD-1、PD-L1表达从而阻止肿瘤细胞发生免疫逃逸,这与抑制β-catenin/N-cadherin信号通路的活性相关。

Transient Absorption Spectral Characterization of Electron Transfer between Fullerenes (C_(60)/C_(70)) and N,N,N′,N′-Tetra(p-methylphenyl)-4,4′-diamino-1,1′-diphenyl Sulphide (TPDAS)

In search of new systems with a photoexcited redox pair which exhibits a strong and stable photoinduced absorption band to understand the photophyscial and photochemical properties of electron transfer between fullerenes (C 60/C 70) and organic donor [N,N,N′,N′-tetra(p-methylphenyl)-4,4′-diamino-1,1′-diphenyl sulphide (TPDAS)], we studied characteristic absorption spectra in the near-IR region obtained from 532 nm nanosecond laser flash photolysis of a mixture of the fullerenes (C 60/C 70) and TPDAS in polar solvents. When fullerenes (C 60/C 70) were photoexcited, the rise of the radical anion of fullerenes (C 60/C 70) with the rapid decay of their excited triplet states were observed in benzonitrile. It can be deduced that the electron transfer reaction does take place from TPDAS to excited triplet state of fullerenes (C 60/C 70). The rate constants (k et) and quantum yields (Φ et) of this process have been also evaluated.

Transfer kinetics of phenol between aqueous phase and N,N-di(1-methyl-heptyl) acetamide in kerosene

The transfer kinetics of phenol between aqueous phase and N,N di(methyl heptyl) acetaminde (N503) in kerosene has been studied using Lewis cell technique. The effects of the factors including the concentrations of phenol in aqueous phase and organic phase, the concentration of N503 in organic phase, the acidity of aqueous phase, the stirring speed and the temperature on the rates of forward and backward extraction of phenol have been examined. The regularity of extraction rate has been obtained. According to experimental results, the rates of both forward and backward extraction of phenol might be controlled by diffusion process. The diffusion step of phenol from aqueous phase to interface for forward extraction and from interface to aqueous phase for backward extraction might be the rate controlling steps.

Preliminary Study on Strategic Water Transfer Project in Western China

Strategic Water Transfer Project of Western China will transfer water from the Dadu river, the Yalong river, the Jinsha river, the Lancang river and the Nujiang river to the Daliushu project as head work of main canal on the Yellow river. And then,the water will be diverted to Neimongol and Xinjiang Uygur autonomous regions,with transfered annual volume of water 80 billion m\+3. The project possesses great comprehensive benefit. The construction of the project will not only change the appearance of the whole Northwest China, but also open up a wide way for the sustainable development of China in future.

Fluorescent sensing of anions based on excited state intramolecular proton transfer in N-(3-hydroxy-2- naphthamido)-N′-phenylthiourea

A neutral N-amidothiourea-based excited state intramolecular proton transfer (ESIPT) anion receptor bearing an o-hydroxynaphthamide fluorophore and a thiourea binding site, N-(3-hydroxy-2-naphthamide)-N’-phenylthiourea (1a), was designed and synthesized. Fluorescence and absorption response of 1a toward anions were assessed in acetonitrile. IR and NMR experiments indicated that the "OH…O=C" intramolecular hydrogen bond (IHB) in 1a was weak so that it only exhibited the short-wavelength normal emission other than ESIPT fluorescence. Due to the high anion binding affinity of the N-amidothiourea binding site and the formation of a hydrogen binding network in the 1a-anion c omplex, 1a underwent structural change upon anion binding that strengthens the "OH…O=C" IHB, leading to the ESIPT and the observation of the long-wavelength ESIPT emission whereas the normal fluorescence is quenched. On the basis of NMR and fluorescence titrations and control experiments with model compounds, a sensing mechanism of the anion-binding-induced ESIPT was proposed.

THERMOSENSITIVITY OF NARROW-DISPERSED POLY(N-n-PROPYLACRYLAMIDE)PREPARED BY ATOM TRANSFER RADICAL POLYMERIZATION

Controlled polymerization of N-n-propylacrylamide was achieved by atom transfer radical polymerization(ATRP) in a N,N-dimethylformamide-water mixture(50 vol%)at room temperature with methyl 2-chloropropinonate as initiator and CuCl/tris(2-dimethylaminoethyl)amine as the catalytic system in a ratio of 1:1:1.High molecular weight homopolymers(up to 3.7×10~4)with narrow molecular weight distribution(less than 1.2)were obtained.The living character of the polymerization was further demonstrated by self-blocking...

燃料电池N型扰流式冷却流道设计及传热分析

质子交换膜燃料电池的功率密度越高,同体积下产生的废热越多,但冷却流道的体积却没有因此增加,甚至还有所减少。为了提升质子交换膜燃料电池内部冷却流道的传热性能,设计出一种N型扰流式冷却流道,采用数值模拟的方法,将扰流式流道与常规直流道进行对比分析。仿真结果表明:采用扰流式流道的燃料电池,在冷却水流速相同时有着更低的温度和更小的温差;冷却水流速增加,温度和温差降幅更大,但压降也更大。扰流式流道在低雷诺数条件下出现混沌对流,导致部分区域冷却水流向与温度发生突变,减小了场协同角,增强了传热能力。扰流式流道内冷却水能更快地吸收更多的热量,占用体积不变但传热性能更好,且结构简单,为冷却流道的设计提供一定的参考价值。

Synthesis of n-Butyl Acetate by Microwave Irradiation Under the Assistance of Solid-Liquid Phase Transfer Catalysis Without Solvent

Introduction Microwave irradiation has been very widely used in heating, cooking and brewing. Several papers which describe the use of domestic microwave ovens to perform rapid organic synthesis in solution have been published. The high heating efficiency gives rise to remarkable rate of reaction and dramatic reduction of reaction time. Nevertheless, its application seems to be limited to these procedures because of

Synthesis of optically active polymers bearing amino acid moieties by atom transfer radical polymerization

We report here an approach toward the synthesis of optically active polyacrylamide bearing amino acid moieties, poly[Nmethacryloyl L-leucine methyl ester] （PMALM）, with controlled average number molecular weight （Mn） and relatively narrow polydispersity index （PDI, Mw/Mn 〈 1.3） by atom transfer radical polymerization （ATRP） using initiating system methyl 2-bromopropionate/CuBr/tris（2-dimethylaminoethyl） amine. The optical properties of the resulting polymers were evaluated from specific optical rotation value and CD spectra.

Density Functional Theory Study on the Histidine-assisted Mechanism of Arylamine N-Acetyltransferase Acetylation

Arylamine N-acetyltransferases （NATs, EC 2.3.1.5） catalyze the N-acetylation of primary arylamines, and play a key role in the biotransformation and metabolism of drugs, carcinogens, etc. In this paper, three possible reaction mechanisms are investigated and the results indicate that if the acetyl group directly transfers from the donor to the acceptor, the high activation energies will make it hard to obtain the target products. When using histidine to mediate the acetylation process, these energies will drop in the 15-45 kJ/mol range. If the histidine residue is protonated, the corresponding energies will be decreased by about 35-87 kJ/mol. The calculations predict an enzymatic acetylation mechanism that undergoes a thiolate-imidazolium pair, which agrees with the experimental results very well.

Photoinduced Electron Transfer between N,N,N′,N′-Tetra-(p-methylphenyl)-4,4-diamino-1,1′-diphenyl Ether (TPDAE) and Fullerenes (C_(60)/C_(70)) by Laser Flash Photolysis

The photoinduced electron-transfer reaction of N,N,N′,N′-tetra-(p-methylphenyl)-4,4′-diamino-1,1′-diphenyl ether (TPDAE) and fullerenes (C 60/C 70) by nanosecond laser flash photolysis occurred in benzonitrile. Transient absorption spectral measurements were carried out during 532 nm laser flash photolysis of a mixture of the fullerenes (C 60/C 70) and TPDAE. The electron transfer from the TPDAE to excited triplet state of the fullerenes (C 60/C 70) quantum yields and rate constants of electron transfer from TPDAE to excited triplet state of fullerenes (C 60/C 70) in benzonitrile have been evaluated by observing the transient absorption bands in the near-IR region where the excited triplet state, radical anion of fullerenes (C 60/C 70) and radical cations of TPDAE are expected to appear.

创伤性老年患者急性肾损伤的预测价值分析

目的探讨几丁质酶3样蛋白1(CHI3L1)、中性粒细胞明胶酶相关脂质转载蛋白(NGAL)及N-乙酰-β-D-氨基葡萄糖苷酶(NAG)对老年创伤患者急性肾损伤(AKI)早期诊断的预测价值。方法老年创伤患者120例,在入科时收集血、尿标本,检测血清和尿CHI3L1、血清和尿NGAL、尿NAG浓度。每6 h记录尿量。入科同时检测血肌酐。采用logistic回归及ROC曲线分析CHI3L1、NGAL、NAG对老年AKI的预测作用。结果多因素logistic回归分析显示血清CHI3L1(SCHI3L1)与血清NGAL(SNGAL)是AKI发生的高危因素。ROC曲线显示预测老年创伤患者AKI的发生,SNGAL的AUC为0.819,SCHI3L1的AUC为0.729,SNGAL联合SCHI3L1的AUC为0.834。结论SCHI3L1与SNGAL是老年创伤患者AKI发生的高危因素,两者均可以预测其AKI的发生,以SNGAL的预测作用更明显,联合指标能提高预测准确率。

用^(15)N叶片标记法研究旱作水稻与花生间作系统中氮素的双向转移

在盆栽条件下 ,采用 1 5N叶片富积标记方法 ,研究了旱作水稻与花生间作系统氮素的双向转移及供氮水平对氮素转移的影响。结果表明 :在 15 kg hm- 2、75 kg hm- 2、 15 0 kg hm- 2等 3个氮肥水平下 ,间作水稻的干物质生物量和氮素吸收量分别为9.4 1g株 - 1、12 .0 6 g株 - 1、13.5 3g株 - 1和 2 0 7.35 mg株 - 1、2 4 1.81mg株 - 1、2 5 9.37mg株 - 1 ,分别比单作水稻增加了 2 1%～ 2 9%、7%～ 2 9%、18%～ 30 %和 4 3.4 3%、4 5 .72 %、32 .81% ,间作对水稻的干物质积累和氮素吸收量有显著促进作用。间作和单作系统中花生的干物质生物量和氮素吸收量间的差异均不显著 ;用花生叶片标记 1 5N试验表明 ,在 3个氮肥水平下花生体内的氮素中分别有 9.93%、5 .6 5 %、4 .2 2 %转移到了水稻植株体内 ,其转移量随土壤氮素水平的提高而降低 ;用水稻叶片标记 1 5N则分别有 4 .39%、2 .0 6 %、1.38%的水稻体内氮素转移到了花生植株体内 ,其转移量也随土壤氮素水平的提高而降低 ;用 1 5N叶片标记的方法证明花生与水稻旱作的间作系统中存在着氮素的双向转移 ,但净转移方向是由花生植株向水稻的氮素转移。对豆科与禾本科间作系统中氮素转移的机理、途径也做了分析和讨论。

低能N^+注入紫花苜蓿生物学效应初步研究

对N+注入紫花苜蓿Medicago sativa所引起生物学效应从生理生化层面进行了较系统的研究,结果显示:在低剂量范围内(0~2.08×1016N+/cm2),N+注入对紫花苜蓿种子存在当代刺激效应,所研究的几种生理生化指标相对CK都有所提高。剂量为6.24×1016~8.32×1016N+/cm2的N+注入对紫花苜蓿种子存在反常辐照损伤效应。即随着N+注入剂量增加,各生理生化指标先降,后升,再降。N+注入使紫花苜蓿过氧化物酶同工酶酶谱发生变异。处理组与对照组扩增出的相同谱带亦存在谱带荧光强度有差异的现象。另外,对N+注入束介导大豆基因组DNA转入紫花苜蓿做了初步研究,结果M2总性状突变率达到19.8%,并得到3株叶片粗蛋白含量较高的突变株(粗蛋白含量比对照高约0.5%)、1株高叶绿素含量的突变株(叶绿素含量比对照高33.3%)。