Chiral (1S)- and (1R)-camphyl α-diimine nickel complexes were synthesized respectively with (1S)-(+) camphorquinone and (1R)-(−) camphorquinone as raw reagents and used as catalyst precursors for olefin polymerizations. It is found that the ligand chirality has no influence on catalytic activity and regioselectivity for olefin polymerizations. Ethylene, propylene, 1-hexene, and 4-methyl-1-pentene polymerizations with the camphyl α-diimine nickel activated by AlEt2Cl can exhibit some living characteristics under the optimized conditions. The resultant polypropylenes and poly(1-hexene)s have significantly narrow molecular weight distributions (PDI < 1.2) in a wide temperature range, even at an elevated temperature of 70 °C. Sustainable period of the linear relationship of M n vs polymerization time depends on temperature for propylene and 1-hexene polymerizations. Additionally, high 1,3-enchainment fraction of 45% is observed even at −60 °C for propylene polymerization using the camphyl α-diimine catalyst due to 2,1-insertion of propylene and chain walking.

All manipulations involving air-and moisture-sensitive compounds were carried out under an atmosphere of dried and purified nitrogen with standard vacuum-line, Schlenk, or glovebox techniques. MaterialsSolvents were purified by standard procedures. 2-Pyridinecarboxaldehyde (99%), 2-benzoylpyridine (98%), 2-bromomesitylene (98%), 2,6-diisopropylaniline (98%), 2,6-dimethylaniline (98%) 2,4,6-trimethylaniline (98%), 4-fluoro-2,6-dimethylaniline (98%) and aniline (98%) were purchased from Aldrich Chemical and used without further purification. Trimethylaluminium (TMA，98%) was purchased from Acros. (DME)NiBr 2 was synthesized by the reaction of 1,2-dimethoxyethane with anhydrous nickel(II) bromide, according to the reported procedures. 6a Methylaluminoxane (MAO) was prepared by partial hydrolysis of trimethylaluminum (TMA) in toluene at 0-60 °C with Al 2 (SO 4 ) 3 ⋅18H 2 O as the water source. The initial [H 2 O]/[Al] in molar ratio was 1.3. Polymerization-grade ethylene and extra-pure-grade nitrogen (99.999%)were further purified before feeding into the reactor by passing them through a DC-IB gas purification instrument. Ligands L1 and L6, and the corresponding nickel complexes 1 and 6 were synthesized by our reported methord. 14 Other commercially available reagents were purchased and used without purification. CharacterizationElemental analyses were performed with a Vario EL series elemental analyzer.Mass spectra were obtained using fast atom bombardment (FAB) LCQ DECA XP or

The field-induced soft smart materials are a kind of soft matter whose macroscopic properties (mechanical, or optical) can be significantly and actively controlled and manipulated by external fields such as magnetic field, electric field, temperature or light. In this paper, we briefly review the research and application progress of the field-induced soft smart materials in recent years and discuss the development problems and trend in this research area. In particular, we focus on three typical field-induced soft materials of smart materials: magnetorheological fluid, electrorheological fluid, and temperature and light sensitive polymer gel.

Field practices show the adaptability of the water displacement curve at the ultra-high water-cut stage is poor. The authors first proposed a new water displacement curve, and then put forward a new method to obtain the parameters in the new curve equation. Then a new characterization equation to describe the relationship between water-oil relative permeability ratio and water saturation is proposed, which is the new water displacement curve's theoretical basis. Finally, based on the case study it is proved that the new curve are more accurate in predicting the development performance at the ultra-high water-cut stage.

SUMMARY Compared with surface waves, guided waves are rarely applied in near-surface investigation. The main reason may lie in the complexity of their dispersion curves. Besides, the study and understanding of guided wave dispersion characteristics are now also inadequate and not deep enough. In this paper, we derived the complete theoretical dispersion curves of P–SV-wave and pure P-wave systems in layered media based on the transmission matrix method and obtained the relative displacement amplitude coefficients at the free surface as a function of frequency and phase velocity for both surface and guided waves. By assigning the value of relative displacement amplitude coefficient to the corresponding point (f,v) on dispersion curve, we got a multi-information diagram called relative amplitude dispersion map (RADM). As a unified description of surface and guided waves, RADM not only shows the velocity–frequency relationship but also represents the polarized energy ratio at the free surface by display colours. The accuracy of RADM was proved by synthetic seismic records, in which RADMs fit well with the corresponding dispersion energy of surface and guided waves. In addition, we designed six models with different Poisson's ratio (PR) and different layer numbers for comparison. It shows that the dispersive vertical-to-horizontal amplitude ratio of guided waves is complex and discontinuous in RADM, which brings great difficulty for mode identification and even affects the subsequent inversion. Tests also show that for high PR layers, the trends of guided P–SV-wave dispersion curves are basically consistent with those of pure P wave. With the decrease of PR, dispersion curves of guided P–SV wave gradually deviate from those of pure P wave. However, RADMs can be greatly consistent with the dispersion energy in either case. This is of great significance for the inversion of near-surface P and S velocities by using dispersion relationships of multimode surface and guided waves.