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ABSTRACTA collaborative exercise is presented where different numerical methods were used to recreate the forces acting on a ship model while executing captive model tests along a channel which has an unsteady cross section (dock opening). Such a layout is typical for a harbour environment. The unsteady nature of the cross section leads to peak values in forces, sinkage and free surface deformations. Experimental tests were conducted by Flanders Hydraulics (with the co-operation of Ghent University). Numerical contributions involve three potential flow methods (Strathclyde University and Pinkster Marine Hydrodynamics) and one RANS method (Federal Waterways Engineering and Research Institute of Germany). All methods are capable of qualitatively predicting the water level variations and sinkage and trim of the vessel. RANS has a better capability of predicting the unsteady sway force and yaw moment acting on the ship including sinkage and trim, but it comes at a much higher computational cost.

Many efforts have been made to improve the neuron integration efficiency on neuromorphic chips, such as using emerging memory devices and shrinking CMOS technology nodes. However, in the fully connected (FC) neuromorphic core, increasing the number of neurons will lead to a square increase in synapse & dendrite costs and a high-slope linear increase in soma costs, resulting in an explosive growth of core hardware costs. We propose a co-designed neuromorphic core (SRCcore) based on the quantized spiking neural network (SNN) technology and compact chip design methodology. The cost of the neuron/synapse module in SRCcore weakly depends on the neuron number, which effectively relieves the growth pressure of the core area caused by increasing the neuron number. In the proposed BICS chip based on SRCcore, although the neuron/synapse module implements 1∼16 times of neurons and 1∼66 times of synapses, it only costs an area of 1.79 × 107 F2, which is 7.9%∼38.6% of that in previous works. Based on the weight quantization strategy matched with SRCcore, quantized SNNs achieve 0.05%∼2.19% higher accuracy than previous works, thus supporting the design and application of SRCcore. Finally, a cross-modeling application is demonstrated based on the chip. We hope this work will accelerate the development of cortical-scale neuromorphic systems.

Objectives: To determine the association between printing works and nasopharygeal carcinoma as well as other diseases. Methods: Demographic data were obtained for those who had worked in a particular newspaper [...]

In the Earth's magnetotail, magnetic reconnection releases stored magnetic energy and drives magnetospheric convection. The rate at which magnetic flux is transferred from the reconnection inflow to outflow regions is determined by the reconnection electric field Er, which is often referred to as the unnormalized reconnection rate. To better quantify the efficiency of reconnection, this electric field Eris often normalized by the characteristic Alfvén speed and the reconnecting magnetic field. This parameter is generally called the normalized or dimensionless reconnection rate R. In this paper, we employ a two‐dimensional fully kinetic simulation to model a magnetotail reconnection event with weak geomagnetic activity (<200 nT of the AEindex) observed by the Magnetospheric Multiscale (MMS) mission on 11 July 2017. We obtain Rand Erfrom direct measurements in the diffusion region and indirect measurements of the rate at the separatrix using a recently proposed remote sensing technique. The measured normalized rate for this MMS event is R∼0.15–0.2, consistent with theoretical and simulation models of fast collisionless reconnection. This corresponds to an unnormalized rate of Er∼2–3 mV/m. Based on quantitative consistencies between the simulation and the MMS observations, we conclude that our estimates of the reconnection rates are reasonably accurate. Given that past studies have found Erof the order ∼10 mV/m during strong geomagnetic substorms, these results indicate that the local Erin magnetotail reconnection may be an important parameter controlling the amplitude of geomagnetic disturbances. Reliable reconnection rates are obtained based on virtual observations in a fully kinetic simulation of an MMS tail reconnection eventThe normalized rates obtained from the simulation and MMS data are 0.15–0.2, indicating the occurrence of fast reconnectionThe observed unnormalized rate is 2–3 mV/m, while higher rates were observed in other events with stronger geomagnetic activities

The amyloid-β protein (Aβ) protein plays a pivotal role in the pathogenesis of Alzheimer’s disease (AD). It is believed that Aβ deposited in the brain originates from the brain tissue itself. However, Aβ is generated in both brain and peripheral tissues. Whether circulating Aβ contributes to brain AD-type pathologies remains largely unknown. In this study, using a model of parabiosis between APPswe/PS1dE9 transgenic AD mice and their wild-type littermates, we observed that the human Aβ originated from transgenic AD model mice entered the circulation and accumulated in the brains of wild-type mice, and formed cerebral amyloid angiopathy and Aβ plaques after a 12-month period of parabiosis. AD-type pathologies related to the Aβ accumulation including tau hyperphosphorylation, neurodegeneration, neuroinflammation and microhemorrhage were found in the brains of the parabiotic wild-type mice. More importantly, hippocampal CA1 long-term potentiation was markedly impaired in parabiotic wild-type mice. To the best of our knowledge, our study is the first to reveal that blood-derived Aβ can enter the brain, form the Aβ-related pathologies and induce functional deficits of neurons. Our study provides novel insight into AD pathogenesis and provides evidence that supports the development of therapies for AD by targeting Aβ metabolism in both the brain and the periphery.

A remote sensing technique to infer the local reconnection electric field based on in situ multipoint spacecraft observation at the reconnection separatrix is proposed. In this technique, the increment of the reconnected magnetic flux is estimated by integrating the in‐plane magnetic field during the sequential observation of the separatrix boundary by multipoint measurements. We tested this technique by applying it to virtual observations in a two‐dimensional fully kinetic particle‐in‐cell simulation of magnetic reconnection without a guide field and confirmed that the estimated reconnection electric field indeed agrees well with the exact value computed at the X‐line. We then applied this technique to an event observed by the Magnetospheric Multiscale mission when crossing an energetic plasma sheet boundary layer during an intense substorm. The estimated reconnection electric field for this event is nearly 1 order of magnitude higher than a typical value of magnetotail reconnection. Magnetic reconnection is an important phenomenon in space plasmas that explosively releases the accumulated magnetic energy. In the Earth's magnetotail, it is known that the released energy by this process leads to aurora substorms. The rate of reconnection, which defines how efficiently the magnetic flux is transferred at the central reconnection region called the diffusion region, is a key parameter to explore such reconnection physics. However, it is very challenging to directly measure this parameter by observing the small‐scale diffusion region in situ. Thus, in this paper, we propose a new remote sensing technique that infers the reconnection rate along the boundary of the whole reconnection region called the separatrix from in situ measurements. In this technique, by observing how rapidly the magnetic flux passes through the separatrix, the rate can be remotely inferred even outside the diffusion region. We confirmed the adequacy of this technique by testing it in a kinetic simulation, and then applied it to a latest observation event by the MMS spacecraft during an intense substorm. The result shows a remarkably high rate. This indicates the positive correlation between the reconnection rate and the substorm strength and strongly motivates future survey using the technique proposed in this paper. A remote sensing technique is proposed to estimate the reconnection electric field using in situ multipoint observations at the separatrixThe proposed technique is successfully applied to virtual observations in a 2‐D fully kinetic particle‐in‐cell simulationThe technique is also applied to a magnetotail MMS event during an intense substorm, and the result shows a large reconnection electric field

This paper investigates the acceleration resistance of a vessel in shallow waters using potential flow and CFD methods. Results indicated a pronounced resistance peak near the critical depth Froude number. The peak’s location and magnitude were sensitive to acceleration intensity and water depth. Excellent agreement between potential flow and CFD methods was found in low and high depth Froude number ranges, suggesting their effectiveness and cost-efficiency. However, non-linear effects affected the resistance peak’s magnitude and position, leading to slight disagreements between the methods. The solvers’ variation was observed to be sensitive to the investigated parameters.

To solve the toxicity problem of blue light emissive three-dimensional lead halide perovskite, zero-dimensional lead-free hybrid halides with low cost and high emission efficiency have become one of the most promising solid-state light emitting materials. Herein, by utilizing discrete [ZnBr4]2−tetrahedrons as optical center, a new series of organic–inorganic hybrid zinc halides of AZnBr4(A = NMPz, MPz, and AMPd) were presented as blue light emitters. Excitingly, these zero dimensional halides exhibit bright blue-light emission with the highest photoluminescence quantum yield of 17.28%, acting as down-conversion phosphors to assembly high-performance white-light emitting diode.

The NASA Magnetospheric Multiscale mission has made in situ diffusion region and kinetic‐scale resolution measurements of asymmetric magnetic reconnection for the first time, in the Earth's magnetopause. The principal theoretical tool currently used to model collisionless asymmetric reconnection is particle‐in‐cell simulations. Many particle‐in‐cell simulations of asymmetric collisionless reconnection start from an asymmetric Harris‐type magnetic field but with distribution functions that are not exact equilibrium solutions of the Vlasov equation. We present new and exact equilibrium solutions of the Vlasov‐Maxwell system that are self‐consistent with one‐dimensional asymmetric current sheets, with an asymmetric Harris‐type magnetic field profile, plus a constant nonzero guide field. The distribution functions can be represented as a combination of four shifted Maxwellian distribution functions. This equilibrium describes a magnetic field configuration with more freedom than the previously known exact solution and has different bulk flow properties. Magnetic reconnection is a fundamental phenomenon in space science and is currently a subject of intense study. During a reconnection event, stored energy that had been bound up in stressed electromagnetic fields is released in the form of heat and the kinetic energy of particles. The NASA MMS mission is currently making measurements of these phenomena in the Earth's Magnetosphere, with unprecedented levels of accuracy and resolution. Our work presents a theoretical model of a structure in space known as an asymmetric current sheet such as the MMS mission encounters during a reconnection event. The model can be implemented into computer simulations, with which to compare to the results from MMS satellite data. This will help us understand the fundamental physics of asymmetric magnetic reconnection. New exact Vlasov‐Maxwell equilibria for 1D asymmetric current sheetsWritten as a combination of four shifted Maxwellian distribution functionsSelf‐consistent with asymmetric magnetic field, temperature, density, and pressure profiles

Temporal, spatial, and velocity‐space variations of electron phase space density are measured observationally and compared for the first time using the four magnetospheric multiscale (MMS) spacecraft at Earth's magnetopause. Equipped with these unprecedented spatiotemporal measurements offered by the MMS tetrahedron, we compute each term of the electron Vlasov equation that governs the evolution of collisionless plasmas found throughout the universe. We demonstrate how to use single spacecraft measurements to improve the resolution of the electron pressure gradient that supports nonideal parallel electric fields, and we develop a model to intuit the types of kinetic velocity‐space signatures that are observed in the Vlasov equation terms. Furthermore, we discuss how the gradient in velocity‐space sheds light on plasma energy conversion mechanisms and wave‐particle interactions that occur in fundamental physical processes such as magnetic reconnection and turbulence. Measuring spatial and temporal variations of space plasmas usually requires choosing between the following two approaches: (a) measure how the quantity of interest changes in time as the plasma flows past a single spacecraft, or (b) compare measurements of the quantity gathered from multiple, spatially separated spacecraft. The first approach requires measurements at two different times from the same spatial location, while the second requires simultaneous measurements taken from multiple spatial points. There are advantages and disadvantages to each of these existing approaches. While single‐spacecraft measurements may be gathered at high time resolution, a known limitation of single‐point data sets is the inability to distinguish between spatial and temporal variations: both a thin, slow‐moving structure and a thick, fast‐moving one could produce the same measured time series of a quantity when sampled at only a single spatial location. In many situations, multipoint measurements, such as those provided by NASA's Magnetospheric Multiscale (MMS) four‐spacecraft mission enable us to overcome that limitation; however, oftentimes electron‐scale structures of interest are even smaller than the close inter‐spacecraft separation of MMS, which means typical techniques for estimating spatial gradients from the four spacecraft also become inaccurate for those events. In this paper, we present a new approach for quantifying variations in a collisionless plasma that only requires information about the plasma particles and fields taken at a singlepoint in time and space. Temporal, spatial, and velocity‐space derivatives of electron phase space density are computed and compared for the first time using the Magnetospheric Multiscale spacecraftSingle‐spacecraft measurements show how parallel electric fields are balanced by electron pressure gradients at Earth's magnetopauseA simplified form of the electron distribution function provides intuition for interpreting nongyrotropic velocity‐space structures Temporal, spatial, and velocity‐space derivatives of electron phase space density are computed and compared for the first time using the Magnetospheric Multiscale spacecraft Single‐spacecraft measurements show how parallel electric fields are balanced by electron pressure gradients at Earth's magnetopause A simplified form of the electron distribution function provides intuition for interpreting nongyrotropic velocity‐space structures

A novel concept for simplification of heat treatment process in a tool steel by the addition of aluminium has been proposed in this research. The addition of 1.08 wt-% aluminium leads to an approximately fully pearlitic state, of which the cementite lamellae are largely spheroidised. Excessive addition of 1.58 wt-% aluminium would result in the formation of a large amount of δ-ferrite. These results are mainly attributed to the synthetic effect of aluminium on the driving force of pearlite transformation and the inter-spacing distance between the proeutectoid carbides. The mechanical properties’ analyses show that aluminium has promising potential to substantially simplify the processing method for developing a relative low-cost mould steel without the concomitant mechanical properties’ reductions.

Epitheliotropic intestinal T-cell lymphoma (EITL, also known as type II enteropathy-associated T-cell lymphoma) is an aggressive intestinal disease with poor prognosis and its molecular alterations have not been comprehensively characterized. We aimed to identify actionable easy-to-screen alterations that would allow better diagnostics and/or treatment of this deadly disease. By performing whole-exome sequencing of four EITL tumor-normal pairs, followed by amplicon deep sequencing of 42 tumor samples, frequent alterations of the JAK-STAT and G-protein-coupled receptor (GPCR) signaling pathways were discovered in a large portion of samples. Specifically, STAT5B was mutated in a remarkable 63% of cases, JAK3 in 35% and GNAI2 in 24%, with the majority occurring at known activating hotspots in key functional domains. Moreover, STAT5B locus carried copy-neutral loss of heterozygosity resulting in the duplication of the mutant copy, suggesting the importance of mutant STAT5B dosage for the development of EITL. Dysregulation of the JAK-STAT and GPCR pathways was also supported by gene expression profiling and further verified in patient tumor samples. In vitro overexpression of GNAI2 mutants led to the upregulation of pERK1/2, a member of MEK-ERK pathway. Notably, inhibitors of both JAK-STAT and MEK-ERK pathways effectively reduced viability of patient-derived primary EITL cells, indicating potential therapeutic strategies for this neoplasm with no effective treatment currently available.

By close inspection of the well polished cross-sections, two categories of interfaces were classified, namely, adhesive bonding between veneering porcelains and zirconia or alumina cores versus reactive bonding between veneering porcelains and cores of glass infiltrated alumina or lithium disilicate based glass ceramics. Argon ion beam cross-section polishing technique was applied to achieve gentle and fine polishing required for high resolution interfacial characterisation by scanning electron microscopy. The observations suggest that it is desirable to enhance the interfacial reactive bonding in order to avoid delamination in alumina and zirconia based composites.

TiC reinforced Ni based coating on Ti–6Al–4V was produced by laser cladding using colloidal graphite powder and pure nickel powder. The microstructure was characterised by SEM, energy dispersive spectroscopy and X-ray diffraction. Microhardness and dry sliding wear properties were investigated, and the results showed that diffusion of the substrate atoms had caused significant in situgrowth of TiC and solid solution strengthening in the coating. TiC was polyhedron and petaline shaped. After laser cladding, the microhardness profile presented novel changes with depth in the coating. The TiC reinforced Ni based coating had good wear resistance on ball on disc dry sliding wear testing. Abrasive wear was the main mechanism.

Pt‐SnOxnanoparticles were synthesized by the ethylene glycol (EG) method in solution of H2PtCl6and SnCl2, with the same concentrations of Pt and Sn, but different pH values. The pH value after the end of platinum reduction reaction was not changed any more, except that a certain amount of water was added to deposit the Pt‐SnOxnanoparticles on the carbon support. The pre‐nanocatalysts were characterized by X‐ray photoelectron spectroscopy (XPS) to investigate the contents of Pt and Sn, and their catalytic activities for ethanol electrooxidation were tested by cyclic voltammetry (CV). The result was that the Sn contents were increasing as the Pt/Sn atomic ratios of 2.2, 2.6, 5.1, 7.4, 8.7, with the decreasing end pH values of 4.5, 5.0, 5.5, 6.5, 7.5, and the Pt contents became less than the addition in the preparation solution while the end pH values were <5.5, but the catalytic activities for ethanol electrooxidation were not so much regularly changed. Besides, from the end pH value of 5.5 to the increasing 9.0, all the platinum nanoparticles could be completely deposited on the carbon support, under the condition that only a certain amount of water was added.

Matching the assistant characters of an electric power steering (EPS) system so that the vehicle achieves a high performance is one of the key technologies in EPS design. A study on the matching strategy of EPS assistant characters is conducive to obtaining a good ‘vehicle performance’ earlier in the design process. This paper describes a method for designing the assistant characters of an EPS system based on the vehicle’s inherent ‘road feel’ denoted here as the steering torque gradient at a 0gor 0.1glateral acceleration under the condition that the steering system is not a power-assisted system. With the aim of obtaining the vehicle’s inherent road feel, the relations between the steering resistant torque and the vehicle’s travel states are analysed on the basis of a two-wheel vehicle model with a uniform normal tyre force distribution in steady state circle cornering. It is found that the vehicle’s inherent road feel decreases with increasing speed especially in the low-speed regions. The matching strategy of EPS assistant characters based on the vehicle’s inherent road feel is presented and illustrated by designing the assistant characters of a sample EPS system utilized in a passenger car. It is found that the EPS system designed by this strategy can supply a good steering feel to the driver.

A new combined process that integrates electrical discharge milling and mechanical grinding is presented. The process is able effectively to machine a large surface area on SiC ceramic with a good surface quality and low cost. The effects of machining conditions on the material removal rate, relative electrode wear ratio, and surface roughness were investigated. The surface microstructures machined by the new process were observed by a scanning electron microscope (SEM), an X-ray diffraction, and an energy dispersive spectrometer. The SEM micrographs show that the surfaces machined at rough machining mode and semi-finish machining mode are characterized by an uneven fusing structure, globules of debris, shallow craters, and micropores; the surface machined at finish machining mode is smooth, and covered by fewer little craters and pockmarks.

AbstractExternal wrist fixators have been widely used to stabilize distal radial fractures. Ideally an external fixator would create a stable environment for the fracture to heal while allowing proper mobility for the wrist. However, this has been a great challenge to the designers.The current study aimed to develop a bridging wrist external fixator that is easy for surgeons to create a stable environment for the fracture to heal while allowing proper wrist mobility for rehabilitative purposes. The kinematic geometry of the wrist-fixator system was described using loop equations defined by homogeneous transformation matrices (HTM) of the joints involved, and was evaluated numerically for a set of system parameters that are determined by surgeons during surgery. The results were validated with geometric models and computer simulation. The contributions of individual clinical parameters to the kinematic geometry of the wrist-fixator system were also analyzed using the Taguchi method.Adequate pin placement and hinge alignment function were found to be critical for the postoperative bridged wrist motion. The results of the current study will be helpful for surgeons to perform fixation using the new wrist fixator and for designers to design new fixators in the future.

AbstractKnowledge of the control of the musculoskeletal system in patients with knee osteoarthritis (OA) during gait is helpful for the development of intervention programs in the management of these patients. The current study aimed to investigate the leg and joint stiffness, aswell as the associated joint kinematics and kinetics, in patients with bilateral medial knee OA during gait. Joint angles, moments and stiffness, as well as leg stiffness from fifteen patients with bilateral knee OA and fifteen normal controls during level walking, were obtained and their values at the beginning and end of single leg stance were compared using a t-test.Patients with knee OA were found to modulate their leg and joint stiffness through acquired specific biomechanical strategies in order to maintain normal temporal-spatial patterns of gait. During weight acceptance, they increased their leg stiffness with increased knee stiffness but unalterd hip and ankle stiffness. During weight release, they modulated their hip and ankle kinetics with increased knee and ankle stiffness to improve the control stability of the limb with unaltered leg stiffness. It is suggested that muscle strengthening exercise intervention and/or rehabilitation for patients with knee OA should focus on activities that develop and/or maintain functions not only of the knee, but also of the overall lower extremity.

The technique of electrical discharge milling insulating ceramics with instantaneous high temperature generated by a discharge channel flowing along a workpiece surface has been developed by the authors. The process uses a thin copper sheet fed to the tool electrode along the workpiece surface as the assisting electrode, using a water-based emulsion as the machining fluid. It is able effectively to machine a large surface area on insulating ceramics, as well as other advanced non-conductive materials such as cubic boron nitride (CBN) and polycrystalline diamond (PCD). The mathematical models of thermal eroding non-conductive Al2O3ceramic with a single pulse discharge are esta lished. The thermal erosion characteristics of insulating Al2O3ceramic with a single pulse discharge have been numerically simulated. The numerical simulation results have been validated by experiment.

K2Zn3(P2O7)2was synthesized by solid state reaction and its crystal structure was determined by ab initiomethod from powder X-ray diffraction (XRD) data. The title compound was determined to be orthorhombic with space group P212121, Z=4, and lattice parameters a=12.901(8) ?, b=10.102(6) ?, and c=9.958(1) ?. Values of lattice parameters from 303 to 573 K were measured by temperature-dependent XRD. Thermal expansion coefficients ?0, lattice parameters, and cell volume at 0 K were determined to be ?0(a)=1.62327?10?4/K, a0=12.855(4) ?, ?0(b)=1.17921?10?4/K, b0=10.070(8) ?, ?0(c)=2.62364?10?4/K, c0=9.880(4) ?, and ?0(V)=6.599?10?2/K, V0=1278.967(0) ?3. The specific heat equation as a function of temperature was determined to be Cp=0.77115+0.00231T?1241.60027T?2?1.4133?10?6T2(J/K g), for temperatures from 198 to 710 K. The melting point estimated from the ?-DTA heating curve is 795 ?C.

This work was undertaken to discuss in depth the vital differences in the morphological development during synthesis, and properties of starch‐g‐poly‐(vinyl acetate) copolymers using two different initiators, potassium persulfate (KPS) and ceric ammonium nitrate (CAN). KPS‐initiated system gave relatively low values of grafting ratio and grafting efficiency, indicating a great tendency for the formation of poly(vinyl acetate) homopolymer (PVAc). Yet, higher values were seen for the CAN‐initiated system. Transmission electron microscope observations indicated a relatively broad distribution of latex particles for the KPS‐initiated system. The surface potential of latex particles was about −3.5 mV, which turned out to be insufficient to maintain stability of latex particles. On the other hand, a uniform particle size distribution was found for the CAN‐initiated system, as the surface potential of latex particles was 21.5 mV. Moreover, radicals on starch molecules were generated directly through a redox reaction with positively charged ceric ion. The hydrophobic PVAc chains were thus grafted on starch, resulting in an amphiphilic graft copolymer, which provides a sufficient stabilization degree as a role of surfactant to render a relatively uniform distribution of latex particles. The synthesized starch‐g‐poly(vinyl acetate) copolymers were further converted to starch‐g‐poly(vinyl alcohol) through saponification, which were subjected to evaluations regarding the biodegradation and cell culture capability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3017–3027, 2006

A short, efficient synthetic route has been developed for the preparation of 2,7-dibromospiro[fluorene-9,9‘-(2‘,7‘-di-n-octyloxyxanthene)], which was subsequently polymerized with the corresponding diborolane through Suzuki coupling to afford a fluorene-based homopolymer, PSFX, that contains a spiroxanthene group functionalized on the C-9 position of each fluorene repeat unit. Single-crystal X-ray diffraction analysis of the dibromo monomer revealed that the spiro-fused fluorene and xanthene moieties lie perpendicular to one another. As a consequence of the incorporation of the spiro pendant group, PSFX possesses a high glass transition temperature and good thermal stability while displaying its stable blue emission in the solid state. A light-emitting diode device prepared using PSFX as the emitting layer exhibits an efficient, stable blue emission; it has a turn-on voltage of 6 V and a maximum external quantum efficiency of 1.74% ph/el. Even when the brightness was increased up to 10³ cd/m² (ca. 11 V), the CIE color coordinates of the resulting EL spectrum remained in the deep-blue region (0.15, 0.07) and the device's efficiency was 1.33% ph/el.

A series of cylcopalladated complexes containing a six-membered chelating ring with the general formula [Pd(Cl)(k²N,C-CH2C6H2(Me)2CH&dbd;NAr)]2 [where Ar = 2,6-(Me)2C6H3− (3a); 2,6-(ⁱPr)2C6H3− (3b)] and the related phosphine-substituted species [PdCl(k²N,C-CH2C6H2(Me)2CH&dbd;NAr)(PR3)] [Ar = 2,6-(Me)2C6H3−, R = Cy (5a); Ar = 2,6-(ⁱPr)2C6H3, R = Cy (5b); Ar = 2,6-(Me)2C6H3−, R = Ph (5c); Ar = 2,6-(ⁱPr)2C6H3−, R = Ph (5d)] have been synthesized. In addition, an ortho-metalated complex [PdCl(k²N,C-C6H4CH&dbd;N(2,6-ⁱPr2C6H3))(PCy3)] (7) was prepared by a similar manner. Crystal structures of 3a, 5b,c, and 7 have been determined. The use of these palladium complexes as catalysts for Suzuki−Miyaura coupling reaction of aryl halides with arylboronic acids in ethanol solution was examined. It is found that this series of palladacycles are considerably active under aerobic conditions. Typically, the best activity (TON ≈ 10⁶) is seen with 3a,b in the coupling reaction of aryl bromide with phenylboronic acid. However, a TEM study showed that the palladium nanoparticles were formed under the reaction conditions, which might be the active species for the catalysis.

Dimerization of terminal arylalkynes at ambient temperature catalyzed by Rh(CO)(PPh3)2Cl (2) in the presence of MeI leads to formation of enyne with high conversion and high regio- and stereoselectivity. A rhodium intermediate captured from oxidative addition of MeI was used for dimerization of alkyne with selectivity controlled by the use of solvents. In aprotic solvent (such as acetone, CH2Cl2, or THF) dimerization of terminal alkynes HC&tbd1;C(p-C6H4X) (1, X = H, a; NO2, b; C(O)H, c; Me, d; CN, e; NMe2, f; CF3, g; F, h; Br, i; I, j) leads to the (E)-1,4-disubstituted enynes 6 (a−k) in high selectivity. However, when MeOH is used as a solvent, the dimerization of 1-arylalkynes containing an electron-withdrawing group affords selectively the (Z)-1,4-disubstituted enyne 8. Requirement of the presence of MeI for this conversion indicates that the process presumably involves initially a six-coordinated rhodium methylacetylide intermediate. Oxidative addition of ICH2CN to 2 yielded the catalytically inactive six-coordinated complex Rh(CO)(PPh3)2(C&tbd1;CPh)(I)(CH2CN) (5a). The analogous complex 5b with a p-nitro group on the phenyl acetylide ligand is characterized by X-ray diffraction analysis.

Electrophilic addition of organic halides to [Ru]CN (1; [Ru] = Cp(PPh3)2Ru) gave the cationic isocyanide complexes {[Ru]CNCH2R}X (R = CN, 2a; R = CH&dbd;CH2, 2b; R = Ph, 2c), which reacted with base (n-Bu4NOH or n-Bu4NF) to give the three-membered-ring azirinyl complexes. For the azirinyl complex with a phenyl group 3c, three isomers, assigned as ruthenium 2H- and 1H-azirinyl complexes, are observed at −20 °C. Reaction of the methyl isocyanoacetate complex {[Ru]C&tbd1;NCH2COOMe}X (2d) with n-Bu4NOH causes hydrolysis of the ester group to give the ruthenium oxazolone complex 4d. The insertion of the C&dbd;O group of acetone, aldehyde, ester, and amide into the C−C bond of the three-membered azirinyl ring of 3a−c yields a variety of five-membered oxazolinyl complexes 5−7. The regiospecificity of the insertion differs from that observed in the photochemically induced carbonyl insertion in the organic azirine system. The diastereoselectivity in the formation of 5−7 is controlled by steric effects. In the formation of the pentamethylcyclopentadienyl oxazolinyl ruthenium complex 7a*, the intermediate 8a* is isolated before cyclization. Molecular structures of 7a* and 8a* have been determined by single-crystal X-ray diffraction analysis. Treatment of 7 with hydride gave [Ru]CN and alcohol.

The mild and efficient reaction between triethyl phosphite and benzylic azides allows us not only to construct rotaxanes in high yield from dibenzo[24]crown-8 (DB24C8) and dibenzylammonium (DBA⁺)-derived threads but also to incorporate di(p-toluidine)[24]crown-8, which binds DBA⁺ ions much more weakly than does DB24C8, into a corresponding [2]rotaxane.

Peptide nucleic acid (PNA) presents a versatile scaffold for chemical modifications that may benefit its solubility and hybridization properties, conjugation chemistry, cell membrane permeability, and so forth. We have employed straightforward chemical methods for the synthesis of PNA monomers containing C5-or C6-modified pyrimidines.The C5-modified pyrimidines are based on 5-hydroxymethyl-uracil or cytosine, or are achieved by cross-coupling from the 5-iodonucleobase derivatives, while C6 modifications are accessed from 6-carboxyuracil (orotic acid). We have also developed an on-resin activation/conversion of uracil-containing PNA oligomers to N4-cytosine-containing derivatives.

A direct method of surface silyl modification and simultaneous surfactant removal of mesoporous silica is investigated in its physicochemical details. Twelve different silanes of various functionalities are studied. The method employs an alcohol solution of silanes to allow the simultaneous surfactant/silyl exchange process, which results in a more uniform monolayer coverage of the surface and a higher amount of surface attachments of silane. We vary the solution concentration of silanes to study the effect on loadings. It is found that the variation of the surface loading of the silyl group follows a Langmuir adsorption model closely. The method gives one a well-controlled monolayer coverage of the surface. The loadings are determined by the exchange equilibrium. Fittings of the loading data to Langmuir adsorption isotherms give one the adsorption equilibrium constants and maximum surface loadings. We categorize the silanes into three different groups according to the values of the equilibrium constants and discuss them with respect to molecular structures. We also report on the extensive characterizations of the surface-functionalized mesoporous materials, such as nitrogen adsorptions, X-ray diffraction, ²⁹Si magic-angle spinning NMR, ¹³C magic-angle spinning NMR, and IR spectroscopy. The method provides one with a convenient and highly controllable approach to the surface functionalization of mesoporous silica.

The first isolation of the monotelluride-bridged chromium carbonyl complexes [Et4N]2[Te{Cr(CO)5}n] (n = 3, [Et4N]2[1]; n = 2, [Et4N]2[2]) has been achieved from the reaction of Te powder with 3 equiv of Cr(CO)6 in the presence of [Et4N]Br in concentrated KOH/EtOH solution. According to X-ray analysis, anion 1 displays a pyramidal geometry with the Te atom bonded to three Cr(CO)5 fragments and anion 2 exhibits a nonlinear structure with the Te atom coordinated with two Cr(CO)5 moieties. Complex 1 can transform to 2 in the presence of Cr(CO)6/KOH/EtOH solution. Conversely, 2 can convert back to 1 upon the reaction with Cr(CO)6 in MeCN. Interestingly, the novel C−O activation of MeOH is observed when 1 was treated with NaOH/MeOH solution at 70 °C, giving the Te-methylated product [Et4N][MeTe{Cr(CO)5}2] ([Et4N][3]). Complex 2 is reactive toward some organic solvents. It can react with CH2Cl2 to form the CH2-bridged tetrachromium complex [Et4N]2[CH2{TeCr2(CO)10}2] ([Et4N]2[4]) and can transform to the known tetrachromium tritelluride complex [Et4N]2[Te3{Cr(CO)5}4], in MeOH solution. Besides, we also found that 2 can undergo oxidative coupling with [Cu(MeCN)4]BF4 in MeOH to form the dimeric open cluster [Te2{Cr(CO)5}4]^2- and can react with NaOH in MeOH to give the dimeric ring complex [Te2Cr4(CO)18]^2-. Complexes 1−4 are fully characterized by spectroscopic methods and single-crystal X-ray analysis. This paper describes that complexes 1 and 2 are important intermediates for a series of tellurium-containing polychromium complexes, and the interesting structural features of the resultant new polychromium carbonyl complexes are compared as well.

Two bulky phosphino−pyridine ligands (6-mesityl-2-((diarylphosphino)methyl)pyridine, P~N) were successfully prepared by means of Suzuki coupling of mesitylboronic acid with 6-bromo-2-picoline followed by phosphinylation. These ligands readily form the palladium and nickel complexes upon treatment with (COD)PdMeCl and (DME)NiBr2, respectively. These P~N chelating Pd(II) and Ni(II) complexes were characterized by both spectral data and X-ray crystallography. The coordination geometry around the metal center is square planar for the Pd(II) complexes and tetrahedral for the Ni(II) complexes. The cationic methylpalladium(II) complexes showed poor activity in the catalytic polymerization of ethylene, but the nickel complexes were highly active with the activation of MAO. The nickel complexes catalyzed the polymerization of ethylene with an Al/Ni ratio of 150, whereas di- and trimerization was observed when the Al/Ni ratio is 500. The obtained polyethylenes are highly crystalline.

Dinuclear ruthenium cyclopropenyl complexes {[Ru]C&dbd;C(CHR)}2C6H4 ([Ru] = (η⁵-C5H5)(PPh3)2Ru, R = CN, 3a; R = CH2&dbd;CH2, 3b; R = Ph, 3c) are prepared by deprotonation of corresponding vinylidene complexes {[Ru]&dbd;C&dbd;C(CH2R)}2C6H4²⁺ (2). For the vinylidene complex 2d (R = CO2Me) with an ester group, the deprotonation reaction leads to formation of the dinuclear bis-furyl complex {[Ru]C&dbd;C(CH&dbd;C(O)OMe)}2C6H4 (5d). Electrophilic addition of TCNQ to both three-membered rings of 3a yields the zwitterionic bis-vinylidene complex {[Ru]&dbd;C&dbd;C[CH(TCNQ)CN]}2C6H4 (4a), which, in the presence of MeOH/n-Bu4NOH, gives the methoxy-substituted bis-cyclopropenyl complex {[Ru]C&dbd;C(C(OMe)CN)}2C6H4 (6a). The proton-induced demethoxylation of 6a generates {[Ru]CC(C(CN))}2C6H4²⁺ (7a). The reaction of TMSN3 with 3a gives the bis-tetrazolate complex {[Ru](N4C)CH(CH2CN)}2C6H4 (8a). Trinuclear tris-cyclopropenyl complexes {[Ru]C&dbd;C(CHR)C6H4C&tbd1;C}3C6H3 (R = CN, 11a; R = CH2&dbd;CH2, 11b; R = Ph, 11c) are obtained from deprotonation of {1,3,5-{[Ru]&dbd;C&dbd;C(CH2R)C6H4C&tbd1;C}3C6H3}³⁺ (10). Complex 2b is characterized by X-ray diffraction analysis, and other complexes are characterized by spectroscopic methods.

Both deuterium-labeled experimental and NMR spectroscopic analyses of poly(vinyl ether) offer the mechanistic insight into the polymerization, indicating that the cationic palladium aqua imine−phosphine complexes [(P~N)PdMe(H2O)]BF4 (P~N = o-C6H4(PPh2)(N&dbd;CHAr)) promote the reaction via proton-transfer initiation. Insertion of vinyl ether into the Pd−Me bond in [(P~N)PdMe(H2O)]BF4 does not proceed, but the single insertion of the same substrate into the Pd−acetal bond of [(P~N)PdCOCH3(L)]BF4 provides the stable inserted product [(P~N)PdCH(OEt)CH2COCH3]BF4, which has been characterized by an X-ray structural determination. However, these palladium complexes do not catalyze the polymerization or copolymerization of vinyl ether and carbon monoxide.

Palladium complexes containing the [(RO)nC6H5-nC&dbd;]N(C6H4PPh2-o) (P~N~O) ligand were synthesized, and the hemilability of the coordinating oxygen donors toward the metal center was studied. In the case of oxygen being a ether functionality (R = Me), acetonitrile readily replaces the tridentate ether donor in [Pd(P~N~O)Me]BF4 (1) to yield [Pd(P~N~O)(MeCN)Me]BF4 (2). The labile nature of the ether donor assists the complex 1 in catalyzing the oligomerization of ethylene. Presumably, the temporary coordination of the ether donor to the vacant site during migratory insertion suppresses the β-elimination, which allows the elongation of the alkyl chain.

Formation of [η⁵:η¹-C5H4C(CH3)&dbd;C(Ph)C(O)](PPh3)2Ru (3a) from the reaction of (η⁵-C5H4COCH3)(PPh3)2RuCl (2a) with PhC&tbd1;CH proceeds via the vinylidene intermediate [(η⁵-C5H4COCH3)(PPh3)2Ru&dbd;C&dbd;CHPh]Cl (4a). In this reaction the oxygen atom of the pendant acetyl group in the cyclopentadienyl ligand of 4a is transferred to Cα of the vinylidene ligand, and this transfer is accompanied by formation of a C&dbd;C bond, giving 3a. Treatment of 2a with LiC&tbd1;CPh affords (η⁵-C5H4C(CCPh)(OH)CH3)(PPh3)2RuCl (6a), and passing 6a through a column packed with alumina also gives 3a. The latter transformation involves a new migration of an acetylide group from exocyclic Cα of a substituted cyclopentadienyl ligand to the Ru center followed by the same oxygen transfer process. The metal acetylide (η⁵-C5H4COCH3)(BINAP)RuC&tbd1;CPh (5c), resulting from the same migration but with no oxygen transfer, is isolated when two PPh3 ligands are replaced by BINAP. The structures of complexes 3a and 6b, a chirophos analogue of 6a, have been determined by X-ray diffraction analysis.

A series of chiral oxovanadium(IV) complexes derived from tridentate N-3,5-substituted and N-3,4-benzo- and N-5,6-benzo-salicylidene-α-amino acids can serve as efficient catalysts for the enantioselective oxidative couplings of various 3-, 6-, and 7-substituted 2-naphthols under O2. The best scenario involves the use of a vanadyl complex arising from 2-hydroxy-1-naphthaldehyde and valine (or phenylalanine) in CCl4, leading to BINOLs in good yields (75−100%) and with enantioselectivities of up to 68%.

Isopiestic measurements have been made for the systems {NaCl +BaCl2+mannitol(sat)(aq)}and {KCl +glycine +mannitol(sat)(aq)}atT=298.15 K. The results agree well with the linear relations for the saturated systems published previously and indicate that if the unsaturated subsystem { (B +C)(aq), where B and C represent the unsaturated solutes} conforms to Zdanovskii’s rule and the Stokes and Robinson relation, then the saturated system { (B +C +A2(sat))(aq), where A2denotes the saturated solute} obeys the relations for the saturated systems.

Treatment of [Cp(dppe)(CO)Mo&dbd;C&dbd;C(Ph)CH2CH&dbd;CH2]I (2) with MeONa caused nucleophilic attack to occur at the terminal CO ligand. This is followed by a coupling reaction of the resulting carbomethoxy group with Cα of the vinylidene ligand accompanied with coordination of the terminal olefin to afford Cp(dppe)MoC(COOMe)&dbd;C(Ph)CH2CH&dbd;CH2 (5). Similar coupling was observed when [Cp(dppe)(CO)Mo&dbd;C&dbd;C(Ph)CH2Ph]I (3) was treated with MeONa, but the reaction afforded the neutral allylic complex Cp(dppe)Mo[CH(COOMe)C(Ph)CHPh] (6). The structures of complexes 5 and 6 have been determined by X-ray diffraction analysis.