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Valveless piezoelectric pumps have the advantages of simple fabrication, lower cost, and high cleanliness. Valveless piezoelectric pump compared with valved piezoelectric pump, the backflow phenomenon is more serious, which greatly limits the application in reality. In this paper, a valveless piezoelectric pump with an inner triangle structure is proposed to increase to the resistance of reverse flow by the inner concave triangle structure to achieve the purpose of reducing backflow. The factors influencing the efficiency of forward flow were analyzed by theoretical modeling. Then, the flow resistance of this valveless piezoelectric pump is numerically calculated by finite element analysis. Finally, the output performance of the pump was experimentally investigated. The experimental results show that when the number of concave triangles in the flow channel are two, the inclination angle (B) are 45°, and the height are 3 mm, the performance of this valveless piezoelectric pump is optimal, and the flow rate and pressure reach 190.86 ml/min and 673 Pa respectively. This study provides some valuable insights to improve its performance and practice. This piezoelectric micropump could generate large flow rates and output pressures with great advantages in the fields of mechanical lubrication and biomedicine. [ABSTRACT FROM AUTHOR]

The ultrasonic attenuation measurement was used to analyze the particle size of heavy oil in water dispersion system for the first time. The particle size and particle size distribution of the 70% dispersion system (Venezuela heavy oil/water) under different conditions were determined. The results show that the ultrasonic attenuation spectrum of the crude heavy oil and water at different frequencies is obviously different. The ultrasonic attenuation method was able to characterize the particle size and particle size distributions of heavy oil/water dispersion. The particle size distribution of the Venezuela heavy oil/water dispersion is uniform and the average particle size is about 100 µm. Whereby 80% particle size of the system is between 60 µm–178 µm and only less than 10% of the particle size is more than 180 µm or less than 55 µm. Moreover, the measurement tendencies of ultrasonic attenuation method are consistent with the results of apparent viscosity. It indicates that the ultrasonic attenuation method can be regarded as an effective approach to determine particle size of heavy oil/water dispersion, which should have high value of application in the online detection in petroleum industry. [ABSTRACT FROM AUTHOR]

Abstract: Well-defined PNNCN pincer ruthenium complexes bearing both strong phosphine and weak oxazoline donors were developed. These easily accessible complexes exhibit significantly better catalytic activity in transfer hydrogenation of ketones compared to their PN3P analogs. These reactions proceed under mild and base-free conditions via protonation–deprotonation of the ‘NH’ group in the aromatization–dearomatization process. [Copyright &y& Elsevier]

Dehydrogenative homocoupling of primary alcohols to formestersand coupling of amines to form imines was accomplished using a classof novel pincer ruthenium complexes. The reactivities of the rutheniumpincer complexes for the direct coupling of amines to form imineswere enhanced by introducing an imine arm to the pincer ligand. Selectiveoxidation of benzylamines to imines was achieved using aniline derivativesas the substrate and solvent. [ABSTRACT FROM AUTHOR]

Abstract: A dearomatized complex [RuH(PN3P)(CO)] (PN3P N, N′-bis(di-tert-butylphosphino)-2,6-diaminopyridine) (3) was prepared by reaction of the aromatic complex [RuH(Cl)(PN3P)(CO)] (2) with t-BuOK in THF. Further treatment of 3 with formic acid led to the formation of a rearomatized complex (4). These new complexes were fully characterized and the molecular structure of complex 4 was further confirmed by X-ray crystallography. In complex 4, a distorted square-pyramidal geometry around the ruthenium center was observed, with the CO ligand trans to the pyridinic nitrogen atom and the hydride located in the apical position. The dearomatized complex 3 displays efficient catalytic activity for hydrogen transfer of ketones in isopropanol. [Copyright &y& Elsevier]

Abstract: Several non-metallocene-type titanium(IV) complexes containing phenoxy-phosphine or thiophenoxy-phosphine ligands of type, (2-R 1-4-R 2-6-PPh2-C6H2X)2TiCl2 (2a: X = O, R 1 = R 2 = t-Bu; 2b: X = O, R 1 = R 2 = cumyl; 2c: X = S, R 1 = SiMe3, R 2 = H) have been synthesized by treating TiCl4 with the corresponding ligands 2-R 1-4-R 2-6-PPh2-C6H2XH in the presence of n-BuLi. The complexes 2a–c were investigated as the catalysts for ethylene with 1-hexene and/or polar alkenes copolymerizations. The catalytic activity and the comonomer incorporation were highly dependent upon catalyst and reaction conditions employed. Among these complexes, 2a can not only promote ethylene/1-hexene living copolymerization at room temperature, but also can utilize ethylene with methyl 10-undecenoate copolymerization. [Copyright &y& Elsevier]

A series of novel titanium(IV) complexes combining a phosphine oxide‐bridged bisphenolato ligand TiCl2{2,2′‐OP‐R3 (4‐R2‐6‐R1‐C6H2O)2}(THF) (6a: R1 = tBu, R2 = H, R3 = Ph; 6b: R1 = Ph, R2 = H, R3 = Ph; 6c: R1 = R2 = tBu, R3 = Ph; 6d: R1 = R2 = cumyl, R3 = Ph; 6e: R1 = tBu, R2 = H, R3 = PhF5) were prepared by the reaction of corresponding bisphenolato ligands with TiCl4 in THF. X‐ray analysis reveals that complex 6a adopts distorted octahedral geometry around the titanium center. These catalysts were performed for ethylene polymerization in the presence of modified methyaluminoxane (MMAO). The effects of reaction parameters on ethylene polymerization behaviors, such as cocatalyst concentration, polymerization temperature, and reaction time were studied in detail. In general, these new complexes exhibited high catalytic activity, good temperature tolerance, and long lifetime for ethylene polymerization. The resulting polymers possess high molecular weight, unimodal distribution, and linear structure. © Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7062–7073, 2008 [ABSTRACT FROM AUTHOR]

The design of novel pincer ligands is described. [ABSTRACT FROM AUTHOR]