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Fe–N–C is hailed as the most promising candidate for replacing costly platinum-based catalysts for proton-exchange membrane fuel cells (PEMFCs) owing to their impressive catalytic activity and low cost. However, the durability of Fe–N–C catalysts remains a major challenge, primarily due to an insufficient understanding of their degradation mechanisms. In this study, we monitor the real-time changes in the electrode during the oxygen reduction reaction (ORR), shedding light on the potential-dependent degradation mechanisms inherent to Fe–N–C catalysts. Utilizing in-situdifferential electrochemical mass spectroscopy, we identify three distinct potential regions with varying degrees of performance loss, notably observing carbon corrosion signals at low potentials. Theoretical calculations and fluorescence probe experiments corroborate that degradation mechanisms at high potentials are primarily driven by strong oxidative potentials that overcome the carbon oxidation energy barrier, whereas the degradation at low potentials is predominantly caused by the high concentrations of reactive oxygen species (ROS) generated during the ORR. The potential-dependent carbon corrosion consequently leads to a similar dependence of demetallation of active sites on the working potential. This study offers a comprehensive understanding of the intrinsic interrelations among various degradation mechanisms, thus paving the way for enhancing the durability of Fe–N–C catalysts in PEMFC applications.

This study describes the synthesis, characterization, and reactivity of aluminum complexes containing the amine‐functionalized pyrrolylaldiminate ligand N‐(2‐dimethylaminoethyl)‐5‐tert‐butyl‐pyrrol‐2‐ylaldiminate ([PyImN]−). The condensation reaction of N,N‐dimethylethylenediamine with 5‐tert‐butylpyrrole‐2‐carbaldehyde in methanol at room temperature produces H[PyImN]. Alkane elimination reactions of MeAlCl2with H[PyImN] in toluene at 110°C and AlR3(R = Me, Et) with H[PyImN] in toluene at −35°C afford [PyImN]AlCl2and [PyImN]AlR2, respectively. Solution NMR studies reveal the coordination preferences of [PyImN]—whose hemilabile amine donor is bound to the aluminum center in [PyImN]AlCl2but unbound in [PyImN]AlR2(R = Me, Et). The catalytic activities of [PyImN]AlMe2in controlled ring‐opening polymerization of ε‐caprolactone are discussed. Aluminum complexes containing the amine‐functionalized pyrrolylaldiminate ligand N‐(2‐dimethylaminoethyl)‐5‐tert‐butyl‐pyrrol‐2‐ylaldiminate ([PyImN]−) have been prepared. Solution NMR studies reveal five‐coordinate [PyImN]AlCl2but four‐coordinate [PyImN]AlR2(R = Me, Et). Complex [PyImN]AlMe2is catalytically active in controlled ring‐opening polymerization of ε‐caprolactone under mild conditions.

ABSTRACTNeutron energy of deuterium-tritium (D-T) generator plays an important role for the application of nuclear energy and nuclear technology. Based on the deuterium energy losing in tritiated titanium (T-Ti) target and differential cross sections of D-T reaction, an improved theoretical formula for calculating the mean neutron energy irradiating a large solid angle sample was proposed. Besides that, the mean neutron energy was discussed under the actual experimental conditions. The results were compared to the reported ratio values of 90Zr(n,2 n)89m+gZr to 93Nb(n,2 n)92mNb reaction cross sections (‘Zr/Nb’ ratio methods) and published theoretical calculated results, respectively. The relative deviations between present work and the ‘Zr/Nb’ ratio methods are below 0.5% and a higher precision was obtained compared with previous published theoretical method. The present work lays a foundation for the application of D-T neutron source in nuclear technology such as nuclear reaction cross section measurement, calibration of neutron detector, and neutron irradiation tests, etc.

The back-streaming white-neutron beamline (Back-n) of the China Spallation Neutron Source is an essential neutron-research platform built for the study of nuclear data, neutron physics, and neutron applications. Many types of cross-sectional neutron-reaction measurements have been performed at Back-n since early 2018. These measurements have shown that a significant number of gamma rays can be transmitted to the experimental stations of Back-n along with the neutron beam. These gamma rays, commonly referred to as in-beam gamma rays, can induce a non-negligible experimental background in neutron-reaction measurements. Studying the characteristics of in-beam gamma rays is important for understanding the experimental background. However, measuring in-beam gamma rays is challenging because most gamma-ray detectors are sensitive to neutrons; thus, discriminating between neutron-induced signals and those from in-beam gamma rays is difficult. In this study, we propose the use of the black resonance filter method and a CeBr3scintillation detector to measure the characteristics of the in-beam gamma rays of Back-n. Four types of black resonance filters, 181Ta, 59Co, natAg, and natCd, were used in this measurement. The time-of-flight (TOF) technique was used to select the detector signals remaining in the absorption region of the TOF spectra, which were mainly induced by in-beam gamma rays. The energy distribution and flux of the in-beam gamma rays of Back-n were determined by analyzing the deposited energy spectra of the CeBr3scintillation detector and using Monte Carlo simulations. Based on the results of this study, the background contributions from in-beam gamma rays in neutron-reaction measurements at Back-n can be reasonably evaluated, which is beneficial for enhancing both the experimental methodology and data analysis.

Two novel glove‐shaped rhenium(I)‐based metallacycle complexes, composed of two bidentate ligands α,α′‐bis(benzimidazol‐1‐yl)‐meta(orortho)‐xylene(bbim) and a tetradentate ligand, 2,5‐pyrazinedicarboxylate(pzdc) with two Re(I) metal centers each are developed and reported. The opening and closure motion of the metaxylene‐linked metallacycle complex were studied via variable temperature proton nuclear magnetic resonance spectroscopy experiment, as well as density functional theory calculation. Our results indicate that the motion of the “capping” phenyl moiety in bbim is accompanied by the swing of the two benzimidazol groups. Both complexes show two different emission bands when excited at two different wavelengths, a violation of the Kasha's rule. Theoretical calculation indicate that the lower‐energy transitions are metal–ligand charge transfer bands, arising from electrons localized to one of the two Re(I) centers to the pzdc ligand, while the higher‐energy ones are assigned to a ligand–ligand charge‐transfer excitation from bbim to pzdc. Results from excited‐state optimized structures confirm that the higher‐energy excitation leads to a closure of the molecule with meta‐bbim, a desirable “molecular catcher” behavior. Our findings provide an important insight for a strategy to design a light‐activated molecular catcher for many interesting applications. Two glove‐shaped rhenium(I)‐based metallacycle complexes were studied with their opening and closure motion characterized. The dual emission observed at different excitation wavelength were found to be associated with different location in the excitation, and a closure movement is associated with the higher energy excitation.

Aluminum is the primary structural material in nuclear engineering, and its cross section induced by 14-MeV neutrons is of great significance. To address the issue of insufficient accuracy for the 27Al(n,2n)26Alreaction cross section, the activation method and accelerator mass spectrometry (AMS) technique were used to determine the 27Al(n,2n)26Alcross section, which could be used as a D-T plasma ion temperature monitor in fusion reactors. At the China Academy of Engineering Physics, neutron activation was performed using a K-400 neutron generator produced by the T(d,n)4Hereaction. The 26Al/27Alisotope ratios were measured using the newly installed GYIG 1 MV AMS at the Institute of Geochemistry, Chinese Academy of Sciences. The neutron flux was monitored by measuring the activity of 92mNbproduced by the 93Nb(n,2n)92mNbreaction. The measured results were compared with available data in the experimental nuclear reaction database, and the measured values showed a reasonable degree of consistency with partially available literature data. The newly acquired cross-sectional data at 12 neutron energy points through systematic measurements clarified the divergence, which has two different growth trends from the existing experimental values. The obtained results are also compared with the corresponding evaluated database, and the newly calculated excitation functions with TALYS-1.95 and EMPIRE-3.2 codes, the agreement with CENDL-3.2, TENDL-2021 and EMPIRE-3.2 results are generally acceptable. A substantial improvement in the knowledge of the 27Al(n,2n)26Alreaction excitation function was obtained in the present work, which will lay the foundation for the diagnosis of the fusion ion temperature, testing of the nuclear physics model, evaluation of nuclear data, etc.

Treatment of PtMe3I in tetrahydrofuran with either in situ prepared [R-PNP]Li ([R-PNP]−= [(R2P-o-C6H4)2N]−; R = Ph, iPr) or H[R-PNP] in the presence of triethylamine at room temperature affords quantitatively fac-[R-PNP]PtMe3. Thermolysis of fac-[R-PNP]PtMe3in benzene solutions generates mer-[R-PNP]PtMe3and ultimately [R-PNP]PtMe and ethane. Complexes mer-[R-PNP]PtMe3represent the first meridional trialkylplatinum(IV) derivatives to date.

In situ lithiation of HN(o‐C6H4PPh2)2(H[1a]) or HN(o‐C6H4PiPr2)2(H[1b]) with nBuLi in THF at −35°C followed by addition of [Ir(μ‐Cl)(COD)]2(COD = 1,5‐cyclooctadiene) in toluene at −35°C generates 5‐coordinate [1a]Ir(η4‐COD) (2a) or 4‐coordinate [1b]Ir(η2‐COD) (2b), respectively. Oxidative addition of N‐H in H[1b] to [Ir(μ‐Cl)(COD)]2affords square pyramidal [1b]Ir(H)(Cl) (3b). Metathetical reaction of 3bwith LiBHEt3in the presence of 1 atm of H2in toluene produces [1b]Ir(H)2(4b). Both 2aand 4bare active for catalytic hydrogenation of olefins and alkynes under extremely mild conditions. Amido PNP complexes of iridium are active in catalytic hydrogenation of olefins and alkynes with dihydrogen under extremely mild conditions.

The queue percentile formulation adopted in the 2010 Highway Capacity Manual (HCM) is empirically based. It contains an overly simplified functional form and parameters such that the accuracy of the back-of-queue percentile estimates is compromised. In view of this, the author applies the Delta method to derive the uncertainty formulation of back-of-queue through the first-order Taylor expansion approximation, assuming that the source of uncertainty comes from arrival flow, saturation flow and, for actuated controller, green time variability from vehicle actuation. As multiplication of the independent, positive random variables results in a lognormal distributed outcome, the back-of-queue percentile is quantified as a lognormal predictive interval function. The simulation study shows that the proposed back-of-queue predictive interval is much more accurate than the HCM counterpart in most of the cases evaluated based on the Kolmogorov–Smirnov goodness-of-fit test. The proposed formulations can be used to quantify the back-of-queue predictive interval for both pre-timed and actuated control, whereas HCM is indifferent to the type of control. As expected, the variability of back-of-queue from the actuated control is less than the pre-timed control in unsaturated condition. The predictive interval profiles become identical when the degree of saturation approaches to unity and maxes out the green time.

A benchmark experiment on 238U slab samples was conducted using a deuterium–tritium neutron source at the China Institute of Atomic Energy. The leakage neutron spectra within energy levels of 0.8–16 MeV at 60° and 120° were measured using the time-of-flight method. The samples were prepared as rectangular slabs with a 30 cm square base and thicknesses of 3, 6, and 9 cm. The leakage neutron spectra were also calculated using the MCNP-4C program based on the latest evaluated files of 238U evaluated neutron data from CENDL-3.2, ENDF/B-VIII.0, JENDL-5.0, and JEFF-3.3. Based on the comparison, the deficiencies and improvements in 238U evaluated nuclear data were analyzed. The results showed the following. (1) The calculated results for CENDL-3.2 significantly overestimated the measurements in the energy interval of elastic scattering at 60° and 120°. (2) The calculated results of CENDL-3.2 overestimated the measurements in the energy interval of inelastic scattering at 120°. (3) The calculated results for CENDL-3.2 significantly overestimated the measurements in the 3–8.5 MeV energy interval at 60° and 120°. (4) The calculated results with JENDL-5.0 were generally consistent with the measurement results.

A series of zwitterionic aluminum complexes of the type AlX[(2‐O‐3,5‐tBu2C6H2)3PZ] (AlX [O3PZ]; X = Cl, Me, Et, and iBu; Z = H, Me) containing C3‐symmetric, formally dianionic, facially tridentate ligands [O3PZ]2−were prepared and structurally characterized. Although serendipitous, these complexes can be readily synthesized by partial protonolysis of AlX3with equal molar (2‐HO‐3,5‐tBu2C6H2)3P (H3[O3P]) or [(2‐HO‐3,5‐tBu2C6H2)3p.m.e](OTf) ({H3[O3PMe]}OTf) in THF at 25°C or elevated temperatures. Alcoholysis of AlMe[O3PMe] (2) with an excess amount of MeOH in refluxing toluene generates AlOMe[O3PMe] (10). Salt metathesis of AlCl[O3PMe] (6) with nBuM (M = Li, MgCl) and NaOR (R = tBu, Ph) in ethereal solutions affords AlnBu[O3PMe] (9) and AlOR[O3PMe] (R = tBu (11), Ph (12)), respectively. Reactivity of 10, 11, and 12with respect to catalytic ring‐opening polymerization of ε‐caprolactone is assessed. A number of zwitterionic organoaluminum complexes of formally dianionic homoscorpionate ligands [(2‐O‐3,5‐tBu2C6H2)3PZ]2−(Z = H, Me) were readily prepared from serendipitous protonolysis of trialkylaluminum with equal molar (2‐HO‐3,5‐tBu2C6H2)3P and [(2‐HO‐3,5‐tBu2C6H2)3PMe](OTf).

The chemistry of anilido phosphine complexes has been popularized since 2003 when N-arylation of the parent o-anilinophosphine was made possible. This Highlight Review summarizes the cumulative progress made in nickel chemistry, paying particular attention to oxidative addition, reductive elimination, CO insertion, olefin insertion, β-hydrogen elimination, metathetical reaction, arene C-H activation, and their collaborative applications to Kumada-type cross coupling catalysis.The chemistry of anilido phosphine complexes has been popularized since 2003 when N-arylation of the parent o-anilinophosphine was made possible. This Highlight Review summarizes the cumulative progress made in nickel chemistry, paying particular attention to oxidative addition, reductive elimination, CO insertion, olefin insertion, β-hydrogen elimination, metathetical reaction, arene C-H activation, and their collaborative applications to Kumada-type cross coupling catalysis.

Sodium borosilicate glasses are candidate materials for high-level radioactive waste vitrification; therefore, understanding the irradiation effects in model borosilicate glass is crucial. Effects of electronic energy deposition and nuclear energy deposition induced by the impact of heavy ions on the hardness and Young’s modulus of sodium borosilicate glass were investigated. The work concentrates on sodium borosilicate glasses, henceforth termed NBS1 (60.0% SiO2, 15.0% B2O3, and 25.0% Na2O in mol%). The NBS1 glasses were irradiated by P, Kr, and Xe ions with 0.3 MeV, 4 MeV, and 5 MeV, respectively. The hardness and Young’s modulus of ion-irradiated NBS1 glasses were measured by nanoindentation tests. The relationships between the evolution of the hardness, the change in the Young’s modulus of the NBS1 glasses, and the energy deposition were investigated. With the increase in the nuclear energy deposition, both the hardness and Young’s modulus of NBS1 glasses dropped exponentially and then saturated. Regardless of the ion species, the nuclear energy depositions required for the saturation of hardness and Young’s modulus were apparent at approximately 1.2 × 1020keV/cm3and 1.8 × 1020keV/cm3, respectively. The dose dependency of the hardness and Young’s modulus of NBS1 glasses was consistent with previous studies by Peuget et al. Moreover, the electronic energy loss is less than 4 keV/nm, and the electronic energy deposition is less than 3.0 × 1022keV/cm3in this work. Therefore, the evolution of hardness and Young’s modulus could have been primarily induced by nuclear energy deposition.

Cross-sections of the (n,2n) reactions for neodymium (Nd) isotopes induced by 14 MeV neutrons were measured in this work by using the activation and relative methods. The measured cross-sections of the 150Nd(n,2n)149Nd, 148Nd(n,2n)147Nd, and 142Nd(n,2n)141Nd reactions were 1854 ± 81, 1789 ± 119, and 1559 ± 98 mb, respectively, at a neutron energy of 14.2 ± 0.2 MeV, and 1485 ± 74, 1726 ± 85, and 1670 ± 119 mb, respectively, at 14.9 ± 0.2 MeV. The results were compared with the experimental values from the reported literature, with the evaluated data from the ENDF/B-VII.1, CENDL-3.1, and JENDL-4.0 libraries, and with the curves calculated by the Talys-1.8 code.

The first example of cobalt-catalyzed selective hydrogenation of nitriles to secondary imines is reported. The results demonstrate the significantly different selectivity compared with the previously reported cobalt catalytic system during the nitrile hydrogenation. A variety of aromatic and aliphatic nitriles are hydrogenated to the corresponding secondary imines.

The reaction of AlCl3with [(2-HO-3,5-tBu2C6H2)3P] (H3[O3P]) results in AlCl[O3PH] ([O3PH]2–= [(2-O-3,5-tBu2C6H2)3PH]2–), which is a zwitterionic molecule containing an unprecedented C3-symmetric but formally dianionic chelate. Derivatization of [O3PH]2–gives [O3PR]2–(R = hydrocarbon), demonstrating the development of a novel class of long elusive scorpionates.

Knowledge of actinides (n,f) fission process induced by neutron is of importance in the field of nuclear power and nuclear engineering, especially for reactor applications. In this work, fission characteristics of 238U(n,f) reaction induced by D-T neutron source were simulated with Geant4 code from multiple perspectives, including the fission production yields, total nubar, kinetic energy distribution, fission neutron spectrum and cumulative γ-ray spectrum of the fission products. The simulation results agree well with the experimental nuclear reaction data (EXFOR) and evaluated nuclear data (ENDF). Mainly, this work was to examine the rationality of the parametric nuclear fission model in Geant4 and to direct our future experimental measurements for the cumulative fission yields of 238U(n,f) reaction.

Identifying the coupling relationships between gusts at different altitudes of weather systems over land is essential to recognize the inherent energy transfer patterns of different types of windy weather systems and design civil structures and infrastructures. Using the time‐lagged convergent cross‐mapping (LCCM) and data obtained from the 356‐m‐high Shenzhen Meteorological Gradient Tower, we present an observational study of the gusts and momentum flux of two super typhoons (STs) and two squall lines (SLs). Compared to STs, the gusts in SLs are characterized by high amplitude bursts and first occur near the surface. Bivariate toy models and observational data showed that LCCM reliably identifies coupling relationships in the nonlinear system. Subsequently, we systematically demonstrated that LCCM can identify long‐distance interactions of multilevel gusts in different types of gale weather systems. Finally, the downward transportation of energy in ST was verified from the perspective of wind structure and turbulent vertical flux. The upper‐level STs gusts varied ahead of the lower‐level gusts, whereas the SLs showed the opposite result, which is consistent with the coupling relationship obtained by the LCCM method. The results of the study are expected to enhance the understanding of the characteristics of multilevel energy transfer of TC and SL boundary layers over land, provide useful information for validating numerical weather prediction models of damaging weather systems, and facilitate gale hazard prevention in coastal regions. Typhoon and squall line are two different weather systems. Although they both produce strong gusts, the characteristics of gusts induced by them are quite different. Understanding the difference of energy transportation in vertical direction in the different weather systems is of great significance for the application of wind energy, the wind resistance design of buildings and the development of early warning systems of gusts. An advanced mathematical method is used to capture the interaction between gusts at different altitudes. It is found that during the typhoon, the variation of upper gust is generally earlier than that of lower gust, and the energy is generally transferred from top to bottom. While during the squall line, the result is opposite. The difference in the internal structure of the two weather systems may be the reason for this result. Gusts in squall lines exerts abrupt changes, whereas gusts changes in typhoons are relatively steadyThe occurrence of gusts in the high level (320 m) is prior to that in lower level (10 m) in typhoons, while the opposite in squall linesThe coupling relationships between gusts at different heights are determined by the vertical structure of typhoons and squall lines Gusts in squall lines exerts abrupt changes, whereas gusts changes in typhoons are relatively steady The occurrence of gusts in the high level (320 m) is prior to that in lower level (10 m) in typhoons, while the opposite in squall lines The coupling relationships between gusts at different heights are determined by the vertical structure of typhoons and squall lines

Flow-induced vibration occurs widely in flow pipelines, and pipeline vibration signals have various frequency characteristics corresponding to different flow regimes. Therefore, an novel noninvasive approach to flow regime identification for wet gas flow in a horizontal pipeline is presented in this paper. The vibration signals were collected by a transducer installed on external wall of pipeline. Empirical mode decomposition (EMD) was used to decompose the vibration signal into different intrinsic mode functions (IMFs), and then the kurtosis of each IMF component for each experimental data was calculated. Finally, the IMF kurtosis feature vector was input to the support vector machine (SVM) to identify three typical flow regimes for wet gas flow including stratified/stratified wavy flow, annular/annular mist flow and slug flow in a horizontal pipeline 50 mm in diameter. The experimental results show that the proposed approach can identify flow regimes effectively, and the identification rate is 80.6%.

The preparation and characterization of zinc complexes supported by potentially tridentate biphenolate phosphane ligands are reported. The in situ prepared dilithium complexes of 2,2′‐tert‐butylphosphanylbis(4,6‐di‐tert‐butylphenolate) ([LtBu]2–) and 2,2′‐phenylphosphanylbis(4,6‐di‐tert‐butylphenolate) ([LPh]2–) react with ZnCl2in tetrahydrofuran (THF) to produce lithium zincates Zn[LtBuLi(THF)]2and Zn[LPhLi(THF)]2, respectively, regardless of the stoichiometry of the starting materials. Alkane elimination reactions of ZnEt2with one equiv. of H2LtBuor H2LPhin THF generate Zn2(LtBu)2(THF) or Zn2(LPh)2(THF)2, whereas those employing two equiv. of the protio ligands afford Zn(LtBuH)2(MeCN) or Zn(LPhH)2(MeCN), respectively. The X‐ray structures of Zn[LtBuLi(THF)]2, Zn2(LtBu)2(THF), Zn2(LPh)2(THF)2, and Zn(LtBuH)2(MeCN) are presented.

In the present work, ZnO nanostructures with tunable size were successfully synthesized on non-seeded Cu substrates by a simple electrodeposition method. The effects of growth conditions on the morphology of the products were studied in detail by scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The as-prepared products exhibited flake-like morphology when the concentration of ZnCl2 was higher enough, while the products showed flower-like morphology when the concentration was lower enough. Field emission investigation indicated that the nanoflowers exhibited good emission properties. The ZnO nanoflowers show potential application as field emitters.

In this paper, one-dimensional ZnS nanostructures were fabricated in a conventional tube furnace by physical vapor deposition method using commercial ZnS powder as the starting materials. The morphologies, microstructures of the products were characterized. The results revealed that the products showed different morphology in different deposition temperature area. The growth mechanisms of the products were also discussed. The nanowires and triangular nanosheets formed via a vapor-liquid-solid process, while the nanobelts formed via a vapor-solid process. The key factors which influenced the morphologies of the products were discussed.

With the lesson from the overturning accident of single-pier bridge and based on the analysis on the size and distribution mode of the load on the bridge surface when the ramp bridge of Tianjin segment in the Jin-Jin Expressway collapsed, this Article drafts the load size and distribution mode are (possibly undertaking up to 4x165t load) studied out for analysis and design of single pier bridge of pier-girder consolidation for the analysis on the calculation of the overturning resistance for single-column girder, and analyzes the overturning resistance capacity of single-column girder with pier-girder consolidation according the planned load size and distribution mode. In addition, this Article proposes the reinforcement measures by adding the column supports at the horizontal direction of the single-column pier, thus effectively improving the overturning resistance capacity of main girder. This Article may be used as the reference for the study of overturning resistance and the reinforcement of single-column pier bridge.

The preparation and characterization of lithium and iron(II) complexes containing a potentially tridentate biphenolate phosphane ligand are reported. Deprotonation of 2,2′‐phenylphosphanyl‐bis(4,6‐di‐tert‐butylphenol) (H2LPh) with one or two equivalents of nBuLi in diethyl ether solutions at –35 °C produces binuclear {Li(HLPh)(OEt2)}2or tetranuclear Li4(LPh)2(OEt2)3, respectively. An X‐ray study of {Li(HLPh)(OEt2)}2showed it to be a Ci‐symmetric dimer composed of two Li(HLPh)(OEt2) units linked with dative O–Li bonds involving phenolate oxygen donor atoms whereas that of Li4(LPh)2(OEt2)3revealed a C2‐symmetric structure in which the two biphenolate phosphane ligands are linked with four lithium atoms that bind to three diethyl ether molecules. Treatment of FeCl2with one or two equivalents of Na2(LPh)(DME)2in THF at –35 °C generates binuclear Fe2(LPh)2(THF)2or mononuclear Fe(HLPh)2(THF)2, respectively. The two iron(II) centers in Fe2(LPh)2(THF)2are antiferromagnetically coupled.

A series of amido phosphinimine ligands of the type [(NAr1)‐o‐(Ph2P=NAr2)C6H4]–(2a: Ar1= 2,6‐C6H3iPr2, Ar2= 2,6‐C6H3iPr2; 2b: Ar1= 2,6‐C6H3iPr2, Ar2= 2,4,6‐C6H2Me3; 2c: Ar1= 2,6‐C6H3Me2, Ar2= 2,4,6‐C6H2Me3), which are electronic variations of monoanionic β‐diketiminates, have been employed to examine the coordination chemistry of zinc. Alkane elimination reactions of ZnR2(R = Me, Et) with H[2a–c] in toluene or ethereal solutions at –35 °C afforded cleanly the corresponding organozinc complexes [2a–c]ZnMe (3a–c) and [2a–c]ZnEt (4a–c). Deprotonation of H[2a–c] with nBuLi at –35 °C generated [2a–c]Li (5a–c), which may be isolated as either solvent‐free complexes or solvated adducts depending on the reaction solvents employed (toluene, OEt2, or THF). Metathetical reactions of 5a·OEt2with Zn(OAc)2in THF at –35 °C produced [2a]Zn(OAc) (6a). These amido phosphinimine derivatives all display solution Cssymmetry on the NMR timescale. The mononuclear nature of the three‐coordinate alkyls 3–4and four‐coordinate acetate 6awas confirmed by single‐crystal X‐ray diffraction analyses. Interestingly, the alkyl complexes 3a–cand 4a–care all active initiators for the catalytic ring‐opening polymerization of ϵ‐caprolactone, whereas the acetate 6ais comparatively inactive.

Along with the economical and the industrialization development, The development domain of rheology will be expanded. At present There are many researches about rock rheological, but the existing model Cannot completely, indication properties of rock, Especially the nonlinear rheological model and rock creep constitutive model of accelerating rheological phase of the study is scarce. After viewing a large number of the composition of rheological models and their laws in current papers, we find out what they are common and give the simplified method of creep equation and relaxation equation .Then we propose the inverse method to establish the new nonlinear rheological element model and the constitutive equation method. This paper focuses on establishing a new method of rheological model which provide technical support.

The present paper gives a detailed inferential reasoning to a new mathematical model for structural strength indicator of soil under dynamic load, which is established on the base of law of conservation of energy and strain energy transformed principle. Through dynamic triaxial test, it points out that the relation of principal stress difference and accumulation subsidence quantity exists threshold value and calculates the structural strength indicator change rule. According to the analysis of structural strength indicator variation rule, it lays emphasis on uniformity of structural strength indicator variation rule under different vibration times and draws the conclusion which is the increasing of the structural strength indicator.

A series of diamagnetic divalent nickel complexes supported by a tridentate amido diphosphine ligand [N(o. 6H4PR2)2]- ([R-PNP]- R = Ph, iPr, Cy) have been prepared and characterized. Deprotonation of H[Ph-PNP], H[iPr-PNP], and H[Cy-PNP] with n-BuLi in ethereal solutions at −35 °C produced the lithium complexes [Ph-PNP]Li(THF)2, [iPr-PNP]Li(solv) (solv = THF, Et2O), and [Cy-PNP]Li(solv) (solv = THF, Et2O), respectively. The reactions of [R-PNP]Li(solv)n with NiCl2(DME) in THF at −35 °C generated [R-PNP]NiCl, which was then reacted with a variety of Grignard reagents to afford the corresponding hydrocarbyl complexes [R-PNP]NiR‘ (R = Ph, R‘ = Me, Et, n-Bu, i-Bu, n-hexyl, CH2SiMe3, Ph; R = iPr, R‘ = Me, Et, n-Bu; R = Cy, R‘ = Me, Et, n-Bu). Of particular interest among the compounds isolated are alkyl complexes that contain β-hydrogen atoms. Treatment of the hydrocarbyl complexes with halogenated hydrocarbons such as dichloromethane, benzyl bromide, and phenyl iodide produced the corresponding nickel halide derivatives. The chloride complexes [Ph-PNP]NiCl, [iPr-PNP]NiCl, and [Cy-PNP]NiCl are all active catalyst precursors for Kumada coupling reactions, including those of alkyls containing β-hydrogen atoms. In addition to spectroscopic data for all new compounds, X-ray structures of [Cy-PNP]Li(OEt2), [Ph-PNP]NiCl, [Ph-PNP]NiBr, [Ph-PNP]NiMe, [Ph-PNP]Ni(n-Bu), [Ph-PNP]NiCH2SiMe3, [iPr-PNP]NiCl, [iPr-PNP]NiMe, [iPr-PNP]Ni(n-Bu), and [Cy-PNP]NiMe are presented.

Estimating incident-induced delay on freeways is important for measuring the impacts of incidents. Information regarding delay can be used for transportation planning or the assessment of traffic improvement projects. Traditional delay estimation methods cannot account for the stochastic attributes of dynamic traffic networks. Introducing the incident duration model and the reduced capacity model into the traditional deterministic queuing model allows researchers to understand better the stochastic characteristics of dynamic networks and to develop a new stochastic incident-induced delay model. The mean delay, the variance of delay, and the expected total delay are estimated on the basis of the proposed model. The analysis shows that the deterministic queuing model can estimate the mean delay as well as the stochastic delay model, but it seriously underestimates the variance of delay and the expected total delay in dynamic networks, which are found to be dominated by incident duration. In addition, depending on the parameter values in the probability distribution of incident duration and reduced capacity, the standard deviation of delay can be higher than the mean delay.

The palladium-catalyzed aryl amination of 1-bromo-2-fluorobenzene with N,N-dimethylethylenediamine quantitatively produces N-dimethylaminoethyl-2-fluoroaniline, which subsequently reacts with KPPh2in 1,4-dioxane to afford N-dimethylaminoethyl-2-diphenylphosphinoaniline HPNN. The reactions of trialkylaluminium with HPNN in toluene generate the corresponding aluminium dialkyl complexes PNNAlR2R Me, Et, i-Bu. The solution NMR spectroscopic and X-ray crystallographic studies are indicative of a trigonal bipyramidal geometry for these aluminium complexes in which the amino nitrogen atom is transto the phosphorus donor of the PNN−ligand. This study presents rare examples of structurally characterized, five-coordinate aluminium hydrocarbyl complexes supported by phosphine-derived ligands.

Delay minimization is one of the most commonly used criteria for optimizing performance of signalized intersections in unsaturated conditions. Under over-saturated conditions, however, minimizing delay alone may not be efficient since queue spillbackmay predominantly impose adverse effects on the system performance. Consequently, queue management becomes important under over-saturated conditions in addition to delay minimization. The paper adapts multi-criteria decision making (MCDM) methods, including deviation minimization and compromise programming, to develop signal control strategies and investigate the system performance of signalized intersections under different traffic scenarios. It is found that two methods are capable of generating effective timing solutions fairly close to Pareto optimality.

An innovative modeling framework to estimate household trip rates using 1995 Nationwide Personal Transportation Survey data is presented. A generalized linear model with a mixture of negative binomial probability distribution functions was developed on the basis of characteristics observed from the empirical distribution of household daily trips. This model provides a more flexible framework and a better model specification for analyzing household-specific trip production behavior. Compared with traditional least squares-based regression models, the parameter estimates from the proposed model are more efficient. Although the mean accuracies from the two modeling approaches are comparable, the mixed generalized linear model is more robust in identifying outliers due to its unsymmetric prediction bounds derived from more correct model specification.

In previous real-time flow prediction studies, the emphasis was placed on the prediction accuracy of the model. The accuracy of the prediction bounds (or limits), on the other hand, was largely ignored. Prediction bounds are, however, important input parameters in such applications as real-time stochastic traffic control, incident detection, and route guidance in the context of dynamic traffic assignment. The objectives of this study are to explore the statistical nature of traffic flows when aggregated at short time intervals and to examine the potential of using the generalized linear model in the dynamic setting to predict traffic flows and provide prediction bounds. Specifically, this study derives recursive algorithms based on the quasi-likelihood principle and performs on-line, multiple-step-ahead predictions of short-term arrival flows for signalized intersections. Preliminary results are presented using a simulated data set from CORSIM and a real data set collected from signalized intersections.

Previous research efforts on developing traffic flow models to account for traffic flow dynamics over transportation networks have centered on macroscopic high-order models. It is unclear whether traffic flow dynamics can be well described using a high-order model formulation, but for real-time traffic control, it is important to have tractable yet accurate models. Described here is a set of tractable traffic flow models based on the Markovian compartment concept. The basic models can be further modified to produce effects analogous to high-order models in capturing unstable traffic behavior during congestion. Special treatments are also made to account for the effects of conflicting flow on the predicted turning exit flow at intersection approaches. The proposed models are evaluated using field data. The results indicate that all the model parameters, including traffic flow parameters and gap acceptance parameters, are reasonably estimated, and the underlying models provide good fits to the field data.

In China's reform program over the last ten years, reforms began in the countryside. The tremendous achievements that resulted have captured the attention of all people around the world and have made them sit up and take notice. Today, the agricultural sphere is once again the hotbed of reform and development in our country; the leadership at the highest level of authority has resolved that we must strengthen our work in agriculture, and, by adopting solid and effective measures, strive to have a good harvest in agriculture over these next two years.

1.On the basis of clinical observations of more than 300 cases of pulmonary paragonimiasis since 1948, of which some 40 cases are followed up for more than 3 years up to 10 years, we think, in order to understand the entire clinical course of lung fluke disease, it is reasonable and advisable to divide into three stages as follows: 1. stage of migrating larvae; 2. stage of mature worms, and 3. stage of recovery.2.The clinical manifestations of the first stage which may develop one month longer after infection, are pleurisy with or without effusion, often bilateral, seropneumothorax, transient pneumonic or bronchopneumonic infiltrations, pericarditis, subcutaneous creeping tumors and other extrapulmonary infestations having clinical symptoms of abdominal pain, chest pain, cough, blood streaked sputum and general malaise. The first stage lasts 3 months to almost one year or even more.3.The main clinical feature of the second stage is recurrent bloody, characteristically chocolate-colored sputum with ova in the sputum and nodular or cystic nodular shadows with changeable degree of perifocal infiltrations demonstrated in serial chest x-ray films. Secondary pleurisy, often encapsulated and with turbid effusion, or pyopneumothorax may be noted at this stage. The duration of the second stage is quite variable, partly depends on the efficacy of the treatment.4.At the third stage, all clinical symptoms and signs disappear with resultant complete disappearance of abnormal chest x-ray findings seen during the second stage. Residual hard nodule or even calcified spot as well as fibrotic lesions may remain.5.In the present paper, the entire clinical features of each stage have been discussed in detail including symptoms and signs, serial chest x-ray findings, laboratory data, diagnostic as well as differential diagnostic clues of lung fluke disease. Extrapulmonary manifestation and treatment are mentioned briefly.

The amido diphosphine complexes PNPPtMe and PNPPtOTf, where PNP−is bis2-diphenylphosphinophenylamide, effectively activate the benzene C–H bond in the presence of an appropriate Lewis acid or base, leading to the formation of PNPPtPh quantitatively.

Two cases of urinary extravasation with hydronephrosis suspected by ultrasound studies and confirmed by radionuclide scans are reported. The value of ultrasound studies in patients with renal transplantation has been reported previously but studies in patients without transplantation are described rarely. Ureteral obstruction with hydronephrosis may cause urinary extravasation. The possibility of urinary extravasation or urinoma should be considered if a sonolucent lesion is seen around a hydronephrotic kidney and a renal scan with 99mtechnetium diethylenetriaminepentaacetic acid may confirm the finding.

Interleukin (IL)-27 is a novel cytokine secreted by stimulation of antigen-presenting cells. No previous studies currently reported the role of IL-27 in the carcinogenesis of osteosarcoma. We aimed to investigate the association of IL-27 polymorphisms and serum IL-27p28 with osteosarcoma risk in a Chinese population.

For Abstract see ChemInform Abstract in Full Text.

For Abstract see ChemInform Abstract in Full Text.