Atomic Layer Deposition of Al2O3 on H-Passivated GeSi： Initial Surface Reaction Pathways with H/GeSi（100）-2 × 1

The reaction mechanisms of Al（CH3 ）3 （TMA） adsorption on H-passivated GeSi（100）-2 × 1 surface are investigated with density functional theory. The Si-Ge and Ge-Ge one-dimer cluster models are employed to represent the GeSi（100）-2 × 1 surface with different Ge compositions. For a Si-Ge dimer of a H-passivated SiGe surface, TMA adsorption on both Si-H^＊ and Ge-H^＊ sites is considered. The activation barrier of TMA with the Si-H^＊ site （1.2eV） is higher than that of TMA with the Ge-H^＊ site （0.91 eV）, which indicates that the reaction proceeds more slowly on the Si-H^＊ site than on the Ge-H^＊ site. In addition, adsorption of TMA is more energetically favorable on the Ge-Ge dimer than on the Si-Ge dimer of H-passivated SiGe.     

广东省南澳岛水产品中硼元素本底值测定研究

水产品中硼元素本底值背景资料对于判断水产品中是否添加硼砂或硼酸至关重要。采用ICP–MS法测定了广东省南澳岛海水养殖的315份不同水产品中的硼含量,为水产品质量安全检测提供本底值判断依据。结果显示,硼含量(mg/kg)由高到低依次为龙须菜干制品(152.324)、干海带(78.628)、龙须菜盐渍样(31.146)、龙须菜鲜样(24.168)、海洋杂草(18.983)、昆布(16.541)、新鲜海带(6.164)、贝类(5.351)、紫菜(4.541)、养殖区海水(4.311)、牡蛎(3.820)、虾类(3.662)、非养殖区海水(3.532)、螃蟹(3.038)、鲍鱼(2.119)、鱼类(2.056)。海洋藻类利用同化作用富集硼元素,而动物性水产品可利用异化作用将硼元素排出体外。     

食用植物油中胆固醇含量的快速测定

将食用植物油直接用无水乙醇完全溶解,经滤膜过滤后,用高效液相色谱法测定其中的胆固醇含量。HPLC条件：Diamonsil C18色谱柱（250mm×4．6mm,5μm）,100％甲醇为流动相,流速1．0mL／min,柱温38℃,检测波长208nm。方法的检出限为50mg／L,加标回收率在91．5％-101．4％之间,测定结果的相对标准偏差为2．12％-4．15％。该法适用于食用植物油中胆固醇含量的快速测定。     

GPC—HPLC—RP法检测熏烧烤肉制品中的苯并（a）芘

采用MPS全自动样品净化系统中的GPC凝胶渗透色谱净化熏烧烤肉制品中的苯并（a）芘（BaP）,并用高效液相色谱荧光法（HPLC—RP）测定BaP的含量。GPC条件：GPC凝胶渗透色谱柱,以环己烷-乙酸乙酯（体积比50：50）为流动相,流速4．7mL／min,收集时间为15—21min。HPLC条件：Diamonsil C18色谱柱（250mm×4．6mm,5μm）;流动相：乙腈-水（体积比88：12）,流速为1．0mL／min;柱温：30℃;进样量：10μL;激发波长：384nm;发射波长：406nm。该方法线性关系良好,加标回收率为82．4％～91.3％,相对标准偏差小于5％,检出限为0．15μg／kg。方法简化了手工操作,有效地去除了熏烧烤肉制品中的色素及脂肪干扰,可应用于熏烧烤肉制品中BaP的测定。     

Improvement of Atomic-Layer-Deposited Al2O3/GaAs Interface Property by Sulfuration and NH3 Thermal Nitridation

Fermi level pinning at the interface between high-h gate dielectric and GaAs induced by unstable native oxides is a major obstacle for high performance GaAs-based metal-oxide-semiconductor （MOS） devices. We demonstrate the improved Al2O3/GaAs interracial characteristics by （NH4）2S immersion and NH3 thermal pretreatment prior to A1203 deposition. X-ray photoelectron spectroscopy （XPS） analysis confirms that sulfuration of GaAs surface by （NH4 ）2S solution can effectively reduce As-O bonds while Ga-O bonds and elemental As still exist at Al2O3 /GaAs interface. However, it is found that N incorporation during the further thermal nitridation on sulfurated GaAs can effectively suppress the native oxides and elemental As in the sequent deposition of Al2O3. Atomic force microscopy （AFM） shows that the further thermal nitridation on sulfurated GaAs surface can also improve the surface roughness.     

离子色谱法测定水产品中甲醛次硫酸氢钠含量

提出了离子色谱法测定水产品中甲醛次硫酸氢钠残留量的方法。样品经0.01mol.L-1氢氧化钠溶液超声浸取,先后经C18固相萃取柱和IC-Ag固相萃取柱净化,萃取液以AS-11(250mm×4mm)为分析柱,不同浓度的氢氧化钾溶液梯度洗脱分离并用抑制型电导检测器测定甲醛次硫酸氢钠含量。甲醛次硫酸氢钠的质量分数在0.1～100mg.kg-1范围内与对应的峰面积呈线性关系,方法的检出限(3S/N)为0.05mg.kg-1。方法用于分析3种水产品样品,加标回收率在94.2%～103%之间,测定值的相对标准偏差(n=5)在2.4%～3.8%之间。     

Preparation of Ultra Low- k Porous SiOCH Films from Ring-Type Siloxane with Unsaturated Hydrocarbon Side Chains by Spin-On Deposition

An ultra-low-dielectric-constant （ultra low-k, or ULK） porous SiOCH film is prepared using a single ring-type siloxane precursor of the 2,4,6,8-tetravinyl-2,4,6,8-tetramethylcyclotetrasiloxane by means of spin-on deposition, followed by crosslinking reactions between the precursor monomers under UV irradiation. The as-prepared film has an ultra low k of 2.41 at 1 MHz due to incorporation of pores and hydrocarbon crosslinkages, a leakage current density of 9.86×10-7 A/cm2 at 1 MV/cm, as well as a breakdown field strength of ~1.5 MV/cm. Further, annealing at 300°C results in lower k （i.e., 1.94 at 1 MHz）, smaller leakage current density （2.96×10-7 A/cm2 at 1 MV/cm） and higher breakdown field strength （about 3.5 MV/cm）, which are likely caused by the short-ranged structural rearrangement and reduction of defects in the film. Finally, the mechanical properties and surface morphology of films are also evaluated after different temperature annealing.     

微波消解–ICP–AES法测定罗布麻叶中16种微量元素

建立微波消解–ICP–AES法测定罗布麻叶中Na,Ca,Mg,Fe,Al,P,Mn,Ni,Cu,Zn,Ti,Se,Ba,Pb,Sr,Cd 16种微量元素含量的方法。以HNO_3–H_2O_2–HF溶液(6∶4∶1)为消解体系,样品经微波消解后,用ICP–AES法对罗布麻叶中16种元素含量进行测定。各元素的质量浓度在0.01~1.00 mg/L范围内与光谱强度呈良好的线性关系,线性相关系数r>0.999,检出限在0.000 5~0.008 0 mg/kg之间。加标回收率为87.56%~101.47%,测定结果的相对标准偏差为1.2%~3.42%(n=6)。该方法操作简单,准确度好,灵敏度高,可用于罗布麻叶中微量元素分析。     

ICP–MS法同时测定儿童洗涤护肤产品中17种有毒有害元素

建立电感耦合等离子体质谱法同时测定儿童洗涤护肤产品中铝、锑、砷、钡、硼、镉、铬、钴、铜、铅、锰、汞、镍、硒、锶、锡和锌17种有毒有害元素的方法。样品采用微波消解法处理,通过在线内标及碰撞反应池技术校正基体效应,并优化了仪器的工作参数。测定锌的线性范围为5~1 000μg/L,砷、镉、铬、汞的线性范围为0.5~100μg/L,其它12种元素的线性范围为1~200μg/L,相关系数均在0.999以上,方法检出限为1.0~25.7μg/kg。加标平均回收率为88.6%~103.2%,测定结果的相对标准偏差均小于5%(n=6)。该方法快速、简便、准确,可应用于儿童洗涤护肤产品中有毒有害元素的测定。