N－硫代磷酰基磺酰脲的合成及除草活性研究

Ｎ－硫代磷酰基磺酰脲的合成及除草活性研究金桂玉,赵国锋,郑健禺（南开大学元素有机化学研究所,天津,３０００７１）关键词硫代磷酰胺,Ｎ－硫代酰基磺酰脲,除草活性磺酰脲类化合物作为高效除草剂已得到广泛地应用和开发［１～７］．为寻找具有除草活性的新化合物,...     

Influence of surface charges on the emission polarization properties of single CdSe/CdS dot-in-rods

We report an experimental investigation of the influence of surface charges on the emission polarization properties of single CdSe/CdS dot-in-rods (DRs), which is important for their polarization-based practical applications. By covering the single DRs with N-type semiconductor indium tin oxide (ITO) nanoparticles, the surface of single DRs is charged by ITO through interfacial electron transfer. This is confirmed by the experimental observations of the reduced photoluminescence intensities and lifetimes as well as the suppressing blinking. It is found that the full width at half maximum of histogram of polarization degrees of the single DRs is broadened from 0.24 (on glass) to 0.41 (in ITO). In order to explain the exprimental results, the band-edge exciton fine structure of single DRs is calculated by taking into account the sample parameters, the emission polarization, and the surface charges. The calculation results show that the level ordering of the emitting states determines the polarization degrees tending to increase or decrease under the influence of surface electrons. The surface electrons can induce an increase in the spacing between the emitting levels to change the populations and thus change the polarization degrees. In addition, different numbers of surface electrons may randomly distribute on the long CdSe/CdS rods, leading to the heterogeneous influences on the single DRs causing the broadening of polarization degrees also.     

Effect of compensation doping on the electrical and optical properties of mid-infrared type-II InAs/GaSb superlattice photodetectors

This paper presents a theoretical study on the electrical and optical properties of mid-infrared type-II InAs/GaSb superlattices with different beryllium concentrations in the InAs layer of the active region. Dark current, resistance-area product, absorption coefficient and quantum efficiency characteristics are thoroughly examined. The superlattice is residually n-type and it becomes slightly p-type by varying beryllium-doping concentrations, which improves its electrical performances. The optical performances remain almost unaffected with relatively low p-doping levels and begin to deteriorate with increasing p-doping density. To make a compromise between the electrical and optical performances, the photodetector with a doping concentration of 3 × 1015 cm-3 in the active region is believed to have the best overall performances.     

Influence of annealing treatment on as-grown Ib-type diamond crystal at a high temperature and high pressure

In this paper,we report on the influence of annealing treatment on as-grown Ib-type diamond crystal under high pressure and high temperature in a china-type cubic anvil high-pressure apparatus.Experiments are carried out at a pressure of 7.0 GPa and temperatures ranging from 1700 C to 1900 C for 1 h.Annealing treatment of the diamond crystal shows that the aggregation rate constant of nitrogen atoms in the as-grown Ib-type diamond crystal strongly depends on diamond morphology and annealing temperature.The aggregation rate constant of nitrogen remarkably increases with the increase of annealing temperature and its value in octahedral diamond is much higher than that in cubic diamond annealed at the same temperature.The colour of octahedral diamond crystal is obviously reduced from yellow to nearly colorless after annealing treatment for 1 h at 1900 C,which is induced by nitrogen aggregation in a diamond lattice.The extent of nitrogen aggregation in an annealed diamond could approach approximately 98% indicated from the infrared absorption spectra.The micro-Raman spectrum reveals that the annealing treatment can improve the crystalline quality of Ib-type diamond characterized by a half width at full maximum at first order Raman peak,and therefore the annealed diamond crystals exhibit nearly the same properties as the natural IaA-type diamond stones of high quality in the Raman measurements.     

Gain-assisted indented plasmonic waveguide for low-threshold nanolaser applications

A subwavelength plasmonic indented waveguide with an active InGaAsP core is proposed.The characteristics of the gap plasmon mode and gain required for lossless propagation are investigated and analyzed by the finite element method.We numerically calculate the normalized mode areas and percentages of energy confined in InGaAsP and metal for plasmonic nanolaser applications.It is shown that the indentation of the sidewalls has an optimal value for which the lasing threshold gain is minimal.The structure could enable low-threshold subwavelength lasing and applications for optoelectronic integrated circuits.     

Thermal Entanglement Between Atoms in the Four-Cavity Linear Chain Coupled by Single-Mode Fibers

Natural thermal entanglement between atoms of a linear arranged four coupled cavities system is studied. The results show that there is no thermal pairwise entanglement between atoms if atom-field interaction strength f or fiber-cavity coupling constant J equals to zero, both f and J can induce thermal pairwise entanglement in a certain range. Numerical simulations show that the nearest neighbor concurrence C_AB is always greater than alternate concurrence C_AC in the same condition. In addition, the effect of temperature T on the entanglement of alternate qubits is much stronger than the nearest neighbor qubits.     

The Michael reaction catalyzed by KF/basic alumina under ultrasound irradiation

The Michael reaction of chalcones as acceptors with various active methylene compounds such as diethyl malonate, nitromethane, cyclohexanone, ethyl acetoacetate and acetylacetone as donors catalyzed by KF/basic alumina results in adducts in high yield within a shorter time under ultrasound irradiation.     

Improved synthesis of 2,2'-arylmethylene bis(3-hydroxy-5,5-dimethyl-2-cyclohexene-1-one) derivatives catalyzed by urea under ultrasound

Synthesis of 2,2′-arylmethylene bis(3-hydroxy-5,5-dimethyl-2-cyclohexene-1-one) derivatives catalyzed by urea via the condensation of aromatic aldehydes and 5,5-dimethyl-1,3-cyclohexanedione was carried out in 80-98% yields at 50 °C in aqueous media under ultrasound. This method provides several advantages such as environment friendliness, high yields and simple work-up procedure.     

Direct measurement of the surface dynamics of supercooled liquid-glycerol by optical scanning a film

The surface dynamics of supercooled liquid-glycerol is studied by scanning the thickness of the glycerol film with single photon detection. Measurements are performed at room temperature well above the glycerol's glass transition temperature. It is shown that the surface dynamics of the glycerol film is very sensitive to the temperature. The linear relationship between the thickness of the film and the viscosity predicted by the Vogel--Fulcher--Tammann--Hesse (VFTH) law is also presented experimentally.     

(+)-O-萘基环状磷酰二胺酯的合成、晶体结构及绝对构型

合成了目标化合物(+)-O-萘基环状磷酰二胺酯,其结构由¹HNMR,³¹PNMR及元素分析确定,并在273K下进行了X射线衍射晶体结构分析.该化合物晶体属正交晶系,P2₁2₁2₁空间群,晶胞参数a=1.0028(4)nm,b=1.1406(4)nm,c=2.4455(8)nm,V=2.7971(18)nm₃,Z=4,Dc=1.212g/cm³,F(000)=1088,μ=0.129mm^-1.晶体的结构收敛最终偏离因子R和wR分别为0.0585和0.0827.Flackx参数为0.03(12).目标化合物中磷原子的绝对构型为S.