Statistical analysis of nitrogen use efficiency in Northeast China using multiple linear regression and Random Forest

Understanding the spatial-temporal dynamics of crop nitrogen(N)use efficiency(NUE)and the relationship with explanatory environmental variables can support land-use management and policymaking.Nevertheless,the application of statistical models for evaluating the explanatory variables of space-time variation in crop NUE is still under-researched.In this study,stepwise multiple linear regression(SMLR)and Random Forest(RF)were used to evaluate the spatial and temporal variation of NUE indicators(i.e.,partial factor productivity of N(PFPN);partial nutrient balance of N(PNBN))at county scale in Northeast China(Heilongjiang,Liaoning and Jilin provinces)from 1990 to 2015.Explanatory variables included agricultural management practices,topography,climate,economy,soil and crop types.Results revealed that the PFPN was higher in the northern parts and lower in the center of the Northeast China and PNBN increased from southern to northern parts during the 1990–2015 period.The NUE indicators decreased with time in most counties during the study period.The model efficiency coefficients of the SMLR and RF models were 0.44 and 0.84 for PFPN,and 0.67 and 0.89 for PNBN,respectively.The RF model had higher relative importance of soil and climatic covariates and lower relative importance of crop covariates compared to the SMLR model.The planting area index of vegetables and beans,soil clay content,saturated water content,enhanced vegetation index in November&December,soil bulk density,and annual minimum temperature were the main explanatory variables for both NUE indicators.This is the first study to show the quantitative relative importance of explanatory variables for NUE at a county level in Northeast China using RF and SMLR.This novel study gives reference measurements to improve crop NUE which is one of the most effective means of managing N for sustainable development,ensuring food security,alleviating environmental degradation and increasing farmer’s profitability.

Novel Zwitterionic Surfactants: Synthesis and Surface Active Properties of N-(3-Alkoxy-2-Hydroxypropyl)-N, N-Dimethyl glycine Betaines

Five new zwitterionic surfactants with long chain alkyl betaine structure incorporated with hydroxylpropyl group have been synthesized. Their structures were identified by elemental analysis, IR (HNMR)-H-1, and (CNMR)-C-13. Surface tension experiments showed that these surfactants have higher surface activity than those without hydroxypropyl group. The values of CMC and gamma(CMC) of these surfactants have been determined.

STUDY ON THE STRUCTURES OF COORDINATION COMPOUNDS OF N-(ortho-METHYL)-AND N-(ortho-METHOXY)-PHENYL IMINODIACETATO-Cu(Ⅱ)

The coordination compounds,{Cu[CH_3C_6H_4N(CH_2COO)_2]}.2H_2O and {Cu[CH_3OC_6H_4N(CH_2COO)_2]}.2H_2O,have been prepared and its crystal struc- tures determined.The final discrepancy factors are R=0.052,R_w=0.061 for (I)and R=0.052,R_w=0.039 for(Ⅱ).The geometry of the coordination poly- hedron with Cu(Ⅱ)is a distorted tetragonal pyramid for(Ⅰ)and an unsym- metrical and extended tetragonal bipyramid for(Ⅱ),respectively.The re- sults of EHMO calculations indicate that the ligand mainly provided the field with very few of its electrons being coordinated to the central atom.

SYNTHESIS OF N,N'-DISUBSTITUTED MONOTHIOXAMIDE AND STUDY OF THEIR REACTIONS WITH DIAMINES

In this paper, six N,N'-disubstituted aonothioxamides were synthesized and the reactions between these monothioxamines and diamines (1,2-diamino ethane and 1,3-diamino propane) were studied. Some new compounds were synthesized by using these reactions.

Novel Phosphonoacetic Acid Derivatives.Synthesis of N-(Ethoxycarbonylmethylphosphonyl)-α-Amino Esters and-α-Amino Phosphonic Acid Esters and Their Bioactivities

A series of novel phosphonoacetic acid derivatives, N-(ethoxycarbonylmethy-ethoxyphosphonyl)-α-amino acid esters and α-amino phosphonates, were synthesized via the reaction of the corresponding phosphonyl chloride with amino acid ester hydrochlorides or amino phosphonates in the presence of a base. The preliminary bioassay shows that some compounds show significant anti-viral activity against tobacco mosaic virus (TMV)

L_p(1≤p≤∞) APPROXIMATION BY AN n-DIMENSIONAL SUBSPACE ON A SET OF n+1 POINTS

Some new characterizations and immediate explicit expressions of best L(1≤p≤∞) approximation and their deviations by an n-dimensional subspace on a set of n+1 points are given.

Effect of N+ Beam Exposure on Superoxide Dismutase and Catalase Activities and Induction of Mn-SOD in Deinococcus Radiodurans

Though bacteria of the radiation-resistant Deinococcus radiodurans have a high resistance to the lethal and mutagenic effects of many DNA-damaging agents, the mechanisms involved in the response of these bacteria to oxidative stress are poorly understood. In this report, the superoxide dismutase (SOD) and catalase (CAT) activities produced by these bacteria were measured, and the change of SOD and CAT activities by 20 keV N+ beam exposure was examined. Their activities were increased by N+ beam exposure from 8x 1014 ions/cm2 to 6x1015 ions/cm2.The treatment of H2O2 and [ CHC13 +CH3 CH2OH ] and the measurement of absorption spectrum showed that the increase in SOD activity was resulted from inducible activities of MnSOD in D. radiodurans AS1.633 by N+ beam exposure . These results suggested that this bacteria possess inducible defense mechanisms against the deleterious effects of oxidization.

A MOLECULAR BEAM INVESTIGATION ON ACTIVATED CHEMISORPTION OF N_2 ON Ni SURFACE AND La FILM

The activated chemisorption of N2 on Ni （poly） and La film was performed on a molecular beam—surface scattering apparatus. Experimental results indicate that the initial sticking probability so increases linearly from 0 to 0.03 as normal component of translational energy of the molecuar beam En increases from 11.00 to 19.91 kcal/mol for N2/Ni system and S0 from 0 to 0. 10 as En from 10. 40 to 19.91 kcal/mol for N2/La system. The apparent activation energy △E are 6.16 kcal/mol and 5.30 kcal/mol for N2/Ni and N2/La systems respectively.

Effects of N on Electronic and Mechanical Properties of H-Type SiC

Structural, electronic and mechanical properties of the nH-SiC （n = 2, 4, 6, 8 and 10） polytypes are calculated by using the first-principles calculations based on the density-functional theory approach. The optimized lattice parameters of nH-SiC are in good agreement with the experimental data. The mechanical properties, including elastic constants, bulk modulus, Young＇s modulus, shear modulus and Poisson＇s ratio, are calculated. The analysis of elastic properties indicates that the effects of n on the mechanical properties of the five nil-SiC structures have no difference. The indirect band gap relationship for the live polytypes is Ebg2H 〉 Ebg4H 〉 Ebg6H 〉 Ebg10H 〉 EbgsH.

Research progress on the mechanism of N6-methylade-nosine methylation modification and proteolipid protein 1 gene in schizophrenia

Schizophrenia (SCZ) is a serious mental illness with unknown etiology, high recurrence rate and high disability rate, which has caused a great burden to individuals and society. There is no clear etiology and pathogenesis. Methylation of N6-methyladenosine (m6A) can regulate the nervous and mental system, and affect the function of the nervous system. Proteolipid protein 1 (PLP1) is a risk gene for schizophrenia. In this study we review the research progress on the pathogenesis of schizophrenia, m6A methylation, and PLP1 gene.

Fate of fertilizer nitrogen and residual nitrogen in paddy soil in Northeast China

The relationship between the fate of nitrogen (N) fertilizer and the N application rate in paddy fields in Northeast China is unclear,as is the fate of residual N.To clarify these issues,paddy field and15N microplot experiments were carried out in 2017 and 2018,with N applications at five levels:0,75,105,135 and 165 kg N ha–1(N0,N75,N105,N135 and N165,respectively).15N-labeled urea was applied to the microplots in 2017,and the same amount of unlabeled urea was applied in 2018.Ammonia (NH3) volatilization,leaching,surface runoff,rice yield,the N contents and15N abundances of both plants and soil were analyzed.The results indicated a linear platform model for rice yield and the application rate of N fertilizer,and the optimal rate was 135 kg N ha–1.N uptake increased with an increasing N rate,and the recovery efficiency of applied N (REN) values of the difference subtraction method were 45.23 and 56.98%on average in 2017and 2018,respectively.The RENwas the highest at the N rate of 135 kg ha–1in 2017 and it was insignificantly affected by the N application rate in 2018,while the agronomic efficiency of applied N (AEN) and physiological efficiency of applied N (PEN) decreased significantly when excessive N was applied.N loss through NH3volatilization,leaching and surface runoff was low in the paddy fields in Northeast China.NH3volatilization accounted for 0.81 and 2.99%of the total N application in 2017 and 2018,respectively.On average,the leaching and surface runoff rates were 4.45% and less than 1.05%,respectively,but the apparent denitrification loss was approximately 42.63%.The residual N fertilizer in the soil layer (0–40 cm) was 18.37–31.81 kg N ha–1in 2017,and the residual rate was 19.28–24.50%.Residual15N from fertilizer in the soil increased significantly with increasing N fertilizer,which was mainly concentrated in the 0–10 cm soil layer,accounting for 58.45–83.54% of the total residual N,and decreased with increasing depth.While the ratio of residual N in the 0–10 cm soil layer to that in the 0–40 cm soil layer was decreased with increasing N application.Furthermore,of the residual N,approximately 5.4%was taken up on average in the following season and 50.2%was lost,but 44.4%remained in the soil.Hence,the amount of applied N fertilizer should be reduced appropriately due to the high residual N in paddy fields in Northeast China.The appropriate N fertilizer rate in the northern fields in China was determined to be 105–135 kg N ha–1in order to achieve a balance between rice yield and high N fertilizer uptake.

Polarization-dependent ultrafast optical nonlinearities of N,N-dimethylformamide at 400 nm

Ultrafast optical nonlinearities of N,N-dimethylformamide(DMF)are studied by using polarized light at 400 nm.Both nonlinear refraction(NLR)and stimulated Rayleigh-wing scattering(SRWS)depend on the polarization state of incident beam,while two-photon absorption(TPA)changes negligibly with polarization state.The polarization dependence of SRWS originates from that of NLR via self-focusing effect.Third-order susceptibility elements of DMF were determined,and a method to distinguish the multi-photon absorption signal from SRWS in Z-scan is provided.These results are helpful for the nonlinear optical research of the novel materials dissolved in DMF.

Electron impact total(elastic+inelastic) cross sections with simple molecules consisting of N & O atoms at 100-1600eV

A model complex optical potential rewritten by the conception of bonded atom, which considers the overlapping effect of electron cloud, is employed to calculate the total (elastic + inelastic) cross sections with simple molecules (N2, O2, NO2, NO, N2O) consisting of N & O atoms over an incident energy range of 100 - 1600 eV by the use of additivity rule at Roothaan-Hartree-Fock level. In the study, the complex optical potential composed of static, exchange, correlation polarization plus absorption contributions firstly uses bonded-atom conception. The qualitative results are compared with experimental data and other calculations wherever available and good agreement is obtained. The total cross sections of electron-molecule scattering above 100 eV can be successfully calculated.

Diversity of supramolecular architecture of H_2salpn coordination compounds based on its flexibility

Two complexes, [ Cu （salpn） ] · NH （ CH3 ）2 （ 1 ） and [Ni （ salpn ）·H20] （ 2 ） （ H2 salpn = N, N-bis（salicylidene）-propane-1,3-diamine） were characterized by IR, element analysis and single crystal X-ray diffraction analysis. Crystal data for complex 1 ： monoclinic, P21/C, a = 1. 097 4×10^-7 cm, b=1.4806x10-7 cm, c=1.0315×10^-7 cm, β=94.43（3）°. The Cu （II） ion in complex 1 is four coordinated with distorted square planar coordination geometry. The crystal structure of com- plex 1 consists of [ Cu（salpn）] coordination complex and a guest molecule NH（ CH3 ）2 that can act as both H-bonding donor and acceptor and plays an important role in constructing supramolecular ar- chitecture. Crystal structure data for complex 2： orthorhombic, Pnma, a = 8. 676 3 ×10^-8 cm, b = 2. 414 5 ×10^-7 cm, c = 7. 538 8×10^-8 cm. The Ni（II） ion in complex 2 is five-coordinated with a but- terfly coordination geometry. The coordinated water molecule plays a key role in hydrogen-bonded networks.

Effect of Different Amendments on Nitrogen Conservation During Simulated Composting

The objectives of this study were to evaluate the effects of different dosages of three amendments—peat,superphosphate,mixture of Mg(OH)2+H3PO4(Magnesium Hydroxide and Phosphorus Acid)on N(Nitrogen)conservation.The simulated composting experiment was carried out in a constant temperature water bath with pig manure and corn straw.The results showed that the ammonia volatilization could be inhibited to some extent under the treatments with fixing agents.Under the same simulated composting conditions,the nitrogen fixation effect of the three kinds of fixatives with the same proportion was as follows:Mg(OH)2+H3PO4>superphosphate>peat.The fixation effect of N increased with the increase of the additives.The N fixation rate of Mg(OH)2+H3PO4 treatment was up to 66%.Compared with the CK(Control Group),the amount of cumulative ammonia emission decreased by 90.3% and the TN(Total Nitrogen)content increased by 39.31% in this treatment.Compared with other two kinds of fixing agents,Mg(OH)2+H3PO4 treatment could not only control N loss in composting process,improve the N nutrient content of compost products,but also could increase P(Phosphorus)and Mg(Magnesium)nutrients.Therefore,it had more popularization value and application prospect.

Accelerated Testing of Devices on Durability and Fatigue Failure

The problems of accelerated testing on durability are formulated and the basic definitions are given. The concept of so-called acceleration function is determined. In the case of linear model, integral function of distribution of time of failure-free operation of a device is determined on the basis of this concept. The criterions of linearity of acceleration function are formulated. The technique of accelerated testing is developed on the basis of correlation that conveys the generalized principle of Palmgren-Miner. This technique guarantees computation of reliability, when load increases permanently or stepwise.

Synthesis of N-(2-^(18)F-fluoropropionly)-Lglutamine and its biodistribution study in mice

Objective To synthesize18F labeled N-(2-18F-fluoropropionyl)-L-glutamine(18F-FPGLN)for tumor PET imaging,and to perform its biodistribution study on normal mice and PC-3 tumorbearing nude mice.Methods4-nitrophenyl-2-18F-fluropropionate(18F-NFP)was synthesized on the MF-2V-IT-I synthesizer and was

The crystal structure and conformation of N-[2,2-dimethyl-3-(2-methylpropenyl)-cyclopropylcarbonyl]-5-methylisoxazolin-3-one

The title compound has been synthesized and its crystal structure was determined by X-ray crystallographic method.The crystal is triclinic,space group P-1,with unit cell dimensions a=6.146 (5),b=8.473(6),c=14.383(5)(?);a=77.47(4),β=82.84(4),γ=69.00(8)°and Z=2.The results obtained reveal that the molecule of the title compound keeps a long conjugative system in- volving C=C double bond,cyclopropane ring,carbonyl group and isoxazolinone ring and adopts a low energy conformation including s-trans of C=C double bond,s-cis of carbonyl group with respect to the three-membered ring and like-s-trans of carbonyl group with the carbonyl group within the heterocyclic moiety.

Studies on sulfinato-dehalogenation XII.Sodium dithionite-initiated addition of N,N-diethyliododifluoroacetamide to multiple bonds

N,N-deithyl-iododifluoroacetamide 1 reacted with alkenes,alkynes in aqueous aceto- nitrile solutions of sodium dithionite and sodium hydrogen carbonate at room temperature to give the corresponding adducts,thus constituting a new method for introducing the CF_2 group into organic mol- ecules.Compound 1 reacted with conjugated olefins 2b,c to afford the iodine-free adducts 7b,c. The adducts 3d-f,from addition of 1 to alkenes 2d-f,could be converted into α,α-difluoro-γ- lactones 5d-f by treatment with silica gel.Compound 1 reacted with ethyl vinyl ether 2i to give aldehyde 8,and perfluoroalkyl or polyfluoroalkyl iodides reacted similarly.A radical mechanism was proposed for the addition reaction.Under the same condition,N,N-diethyl-bromodifluoroacetamide produced only the corresponding sulfinate Et_2NC(O)CF_2SO_2Na.