BEPC共振事例的碎裂特性

发现e⁺e^－→J/ψ→3g三胶子碎裂的末态强子多重数〈n〉满足与e⁺e^－→q₀q₀连续区事例相同的普适质量关系〈n〉=A2S+12I+1exp(–bm2).表明胶子、夸克碎裂成强子时有相同的规律性.同样可以把参数A解释为直生介子、重子多重数〈M〉+〈B〉.虽然对Υ→3g与连续区事例进行比较,末态重子多重数增高2.5倍,但是利用我们对J/ψ→3g共振区的计算研究,没有发现J/ψ→3g事例有类似的特征.     

Traveling wave tube measurements for low-frequency properties of underwater acoustic materials

A traveling wave tube measurement technique for measuring acoustic properties of underwater acoustic materials was developed.Water temperature and pressure environments of the ocean can be simulated in a water-filled tube,and the acoustic parameters of samples of underwater acoustic materials are measured in the range of low-frequency.A tested sample is located at central position of the tube.A pair of projectors is separately located at both ends of the tube.Using an active anechoic technique,the sound wave transmitting the tested sample is hardly reflected by the surface of secondary transducer.So the traveling sound field is built up in the tube.By separately calculating the transfer functions of every pair of double hydrophones in the sound fields from the both sides of the sample,its reflection coefficients and transmission coefficients are obtained.In the measurement system,the inside diameter of the tube isΦ208 mm,the working frequency range is from 100 to 4000 Hz,the maximum pressure is 5 MPa.The reflection coefficients and transmission coefficients of a water layer and a stainless steel layer samples are measured actually and calculated theoretically.The results show that the measured values are in good agreement with the values calculated,and the measurement uncertainty is not greater than 1.5 dB.     

The 1:1 adduct of 5‐methylbenzene‐1,3‐diol (orcin) and 1,4‐di­aza­bicyclo­[2.2.2]­octane

In the title adduct, C₆H₁₂N₂·C₇H₈O₂, the orcin and 1,4‐di­aza­bi­cyclo­[2.2.2]­octane moieties are held together by O—H⋯N hydrogen bonds. One‐dimensional chiral hydrogen‐bonded chains are formed along the b axis. Neighbouring chains are held together principally by van der Waals interactions and are interrelated by translation, resulting in a chiral layer.     

微电喷雾与纳电喷雾装置的制作

研制了实验室可自制的多种微／纳电喷雾喷头。喷头制作简单且易于操作,并利用利血平标准样品测试了各种微／纳电喷雾喷头的性能,显示了其高灵敏、低消耗的显著特点。     

一种超快时间分辨速度干涉仪的设计和理论研究

在单发、超快时间分辨的测量技术中,线性啁啾脉冲和光谱仪的结合使用是一种常见方法.本文以成像型光谱仪为记录系统,利用线性啁啾脉冲的频-时对应关系,设计了一种应用于自由面速度超快测量的速度干涉仪.理论研究了其工作原理和适用范围,该速度干涉仪可以实现皮秒量级的时间分辨,且速度灵敏度可调、易调,大大拓宽了速度干涉仪的应用范围.数值模拟了系统的测速过程,结果表明,重建速度信号与给定物体速度符合得很好,进一步验证了系统的可行性.     

Controlling two-dimensional electron localization via phase-controlled absorption and gain in the three-coupled quantum wells

We investigate two-dimensional (2D) electron localization via phase-controlled absorption and gain of a weak probe field in an asymmetric semiconductor three-coupled quantum well (TCQW) with a closed loop under the action of two orthogonal standing-wave fields. It is found that we can achieve high-precision and high-resolution 2D electron localization via properly varying the parameters of the system. The influences of direct one-photon transition and indirect three-photon transition on the precision of probe absorption–gain spectra are also discussed in details. Thus, the proposed scheme shows the underlying probability for the formation of the 2D electron localization in a solid.     

Strong enhancement of streaming current power by application of two phase flow

We show that the performance of a streaming-potential based microfluidic energy conversion system can be strongly enhanced by the use of two phase flow. Injection of gas bubbles into a liquid-filled channel increases both the maximum output power and the energy conversion efficiency. In single-phase systems the internal conduction current induced by the streaming potential limits the output power, whereas in a two-phase system the bubbles reduce this current and increase the power. In our system the addition of bubbles enhanced the maximum output power of the system by a factor of 74 and the efficiency of the system by a factor of 163 compared with single phase flow.     

New Efficient Synthesis of 5,6-Disubstituted-3-phenyl-1,2,3-triazolo[4,5-d]pyrimidin-7-ones via a Tandem Aza-Wittig Reaction

Twelve novel 5,6-disubstituted-3-phenyl-1,2,3-triazolo[4,5-d]pyrimidine-7-ones 5a–5l were designed and successfully synthesized via tandem aza-Wittig and annulation reactions of the corresponding iminophosphorances 2, aromatic isocyanate, and substituted thiophenols in satisfactory yields. The results from the preliminary bioassay indicated that some of these compounds possess inhibitory activities against the root and stalk of Brassica napus(rape) as well as Echinochloa crusgalli (barnyard grass) at the dosages of 100 mg/L and 10 mg/L, respectively.     

Supramolecular Architectures of Four New Transition Metal Complexes with 3‐[4‐(Carboxymethoxy)phenyl]propanoic Acid and N‐[4‐(Carboxymethoxy)phenyl]iminodiacetic Acid

Four new transition metal complexes: [Cu(Hcppa)₂(H₂O)₂] ( 1 ), [Co₂(cppa)₂(H₂O)₁₀] ( 2 ), [Co₃(cpia)₂(H₂O)₈] · 2H₂O ( 3 ) and [Ni₃(cpia)₂(H₂O)₁₂] · 6H₂O ( 4 ) {H₂cppa = 3‐(4‐(carboxymethoxy)phenyl]propanoic acid; H₃cpia = N‐[4‐(carboxymethoxy)phenyl]iminodiacetic acid} were synthesized and characterized. Complexes 1 and 2 show mononuclear structures, complexes 3 and 4 exhibit dinuclear structures. All complexes extend to 3D supramolecular networks through hydrogen bonds, of which complexes 3 and 4 display microporous structures. In complexes 2 – 4 the water clusters are trapped by the cooperative association of coordinate interactions as well as hydrogen bonds, forming different 1D metal‐water chain structures. Thermal stabilities of complexes 1 – 4 were discussed.     

Derivatization-independent cholesterol analysis in crude lipid extracts by liquid chromatography/mass spectrometry: applications to a rabbit model for atherosclerosis

Direct measurement of various sterols in crude lipid extracts in a single experiment from limited biological samples is challenging. Current mass spectrometry (MS) based approaches usually require chemical derivatization before subjecting to MS analysis. Here, we present a derivatization-independent method for analyzing various sterols, including cholesterol and its congeners, using liquid chromatography and atmospheric pressure chemical ionization mass spectrometry. Based on the specific tandem mass spectrometry pattern of cholesterol, multiple reaction monitoring (MRM) transitions were used to quantify free cholesterol and its fatty acyl esters. Several cholesterol oxidation products could also be measured using the upfront liquid chromatography separation and specific MRM transitions. The method was validated alongside established enzymatic assays in measuring total cholesterol. As a proof of concept, we analyzed plasma sterols in rabbits administrated with a high cholesterol diet (HCD) which is a classical atherosclerotic model. Free cholesterol, cholesterol esters, 7-hydroxycholesterol, and 7-ketocholesterol were elevated in plasma of rabbits on HCD. This method could also serve as an excellent tool for quantitative analysis of other sterols such as ergosterol and sitosterol in other organisms beside mammalian. In Saccharomyces cerevisiae, our results indicated dramatic increases of the ratio of ergosterol esters to free ergosterol in both yeh2Δ and tgl1Δ cells, which are consistent with the function of the respective enzymes.