A study of the analytical behaviour of selected synthetic and naturally occurring coumarins using liquid chromatography, ion trap mass spectrometry, gas chromatography and polarography and the construction of an appropriate database for coumarin characterisation

The aim of this paper is to provide analytical chemical information on a range of naturally occurring and synthetic coumarins. This analytical chemical information on liquid chromatography-electrospray ionisation-mass spectrometry (HPLC-ESI-MS), ion trap mass spectrometry (ESI-MSⁿ), gas chromatography-flame ionisation detection (GLC-FID) and polarographic behaviour is then incorporated into a database which is of use in identifying unknown coumarins isolated from natural sources. This paper is also concerned with understanding the effect of functional groups in coumarins on their analytical chemical behaviour using the above techniques.     

Double optical waveguide in Cu-doped KNSBN crystal formed by MeV boron ion implantation

We reported for what is to be believed the first time a double optical waveguide in a Cu-doped potassium sodium strontium barium niobate (KNSBN) crystal formed by double boron ion implantation. The energy and dose of B⁺ and B³⁺ ions were (3+6) MeV and (2+2)×10¹⁴ ions/cm², respectively. The refractive index profile of the waveguide showed a double-barrier confined shape, which suggested the formation of a two-layer waveguide structure. The two waveguide layers were with thickness of 2.6 and 2 μm, respectively, which was in a good agreement with the parameters obtained from transport and range of ions in matter 98 (TRIM) code simulation. The nuclear energy loss distribution of the MeV B ions implanted into this crystal had a similar shape to that of the waveguide index profile, which means an inherent relationship between the waveguide formation and the energetic energy deposition.     

AMMONIUM TREATMENT OFNATURAL CLINOPTILOLITE AND ITS CHARACTER OF ION-EXCHANGE

1NTRODUCTIONAsoneofnutritionalelementsforcrops,potassiumsaltshaveusedwidelyinmanyfields.TheapplicationofpotassiumsaltshasbeenpaidmoreattentioninChinabecauseofthelackofnaturalpotassiumresources.Onehasknowntheionexchangecharacterofnaturalzeoliteanditsapplicationforalongtime,especiallytheselectiveionexchangepropertiesofnaturalclinoptiloliteforK ,bywhichthepotassiumrecoverywasinvestigatedfromseawaterandothernaturalbitt.,.[l--3J.Inpreviousstudies,NaCIhasbeenusedasatypechangeagentofzeolite,bu…     

Hyperfine structure and isotope shifts in the 5d6s2 a2D3/2--5d6s(a3D)6p z4F5/2 ° transition of Hf II

The hyperfine structure and isotope shifts of the transition between the 5d6s² a²D_3/2 ground state and the 5d6s(a³D)6p z⁴F_5/2 ^° excited state of singly ionized hafnium at \lambda=340 nm have been investigated by laser spectroscopy using a radio-frequency quadrupole ion trap. The magnetic dipole coupling constant A and electric quadrupole coupling constant B of the two atomic levels for both stable isotopes ¹⁷⁷Hf and ¹⁷⁹Hf are determined. The changes of mean square nuclear charge radii \delta[ r²] of the stable Hf isotopes and the radioactive isotope ¹⁷²Hf (T_1/2=1.87a) have been extracted from the data. This revised version was published online in August 2006 with corrections to the Cover Date.     

线型离子阱中冷却离子所需高纯度氦气的渗透与实验

利用氦的渗透性质,向超高真空系统中充入高纯度氦缓冲气体,可以降低离子阱中囚禁离子的运动速度,减小二级多普勒频移,增加离子的存储时间,提高线型离子阱微波频标的稳定度.实验上得到了氦气渗透的实验参数、特性以及对系统真空度的影响、实现了用温度调节精确的控制充入氦气的分压强.     

离子束和等离子体对聚醚型聚氨酯表面的联合影响

首先采用等离子聚合法使六甲基二硅氧烷沉积于聚醚型聚氨酯表面，再利用硅离子以不同的剂量时表面进行轰击。结果表明：在2×10(15)cm(-2)剂量下注入使材料表面的凝血时间从6分钟提高到16．8分钟，同时表面浸润性也明显改善，而且这些性能的变化要比单纯注入的更稳定和更有规律。X射线光电子能谱分析表明：离子束和等离子体的联合处理不仅打断了表面的一些化学键，而且在表面形成了诸如Si-N，O-Si-O基团以及硅原子。这些结构上的变化会影响生物医学性能。     

氢离子敏场效应晶体管工作机理及其界面电势差温度特性的探讨

本文运用表面基模型分析了氢离子敏场效应晶体管的工作机理,推导了敏感膜与溶液间的界面电势差及其温度系数,提出了经典的Nernst方程是表面基密度趋于无穷时的一种极限形式.界面电势差及其温度系数的实验数据与通过表面基模型分析得出的结论相吻合,为该模型的正确性提供了论据.     

季铵酚离子在水／硝基苯界面的转移

油/水界面上的电化学研究是近年来电化学研究中的一个新领域,对膜电化学的发展具有重要意义。目前研究油/水界面电化学中普遍使用循环伏安(CV)法和循环线扫电流计时电位(CLC)法。有关抗生素在油/水界面的转移已有报导,本文用CLC法和CV法对肌肉松弛剂季铵酚离子在水/硝基苯界面的转移行为进行了研究。 所用三碘季铵酚为中国科学院生物化学研究所生产的化学试剂,其他试剂及仪器均与前文相同     

Rapid thermal annealing of dual Si and P implants in InP

In this study we evaluate the effects of dual implantation with different doses of Si and P on dopant activation efficiency and carrier mobility in InP:Fe. The implants were activated by a rapid thermal annealing step carried out in an optimized phosphoruscontaining ambient. For high dose implants (10¹⁴–10¹⁵ cm⁻²), which are typically employed for source/drain regions in FETs, dual implantation of equal doses of Si and P results in a higher sheet carrier concentration and lower sheet resistance. For 10¹⁴ cm⁻² Si implants at 150 keV, the optimal P co-implant dose is equal to the Si dose for most anneal temperatures. We obtain an activation efficiency of ∼70% for dual implanted samples annealed at 850° C for 10 sec. The high activation efficiencies and low sheet resistances obtained in this study emphasize the importance of stoichiometry control through the use of P co-implants and a phosphorus-containing ambient during the thermal processing of InP.