Effect of Incident Intensity on Films Growth in Pulsed Laser Deposition

Incident intensity, defined by the amount of particles deposited per pulse, is an important parameter in the film growth process of pulsed laser deposition （PLD）. Different from previous models, we investigate the irreversible and reversible growth processes by using a kinetic Monte Carlo method and find that island density and film morphology strongly depend on pulse intensity. At higher pulse intensities, lots of adatoms instantaneously diffuse on the substrate surface, and then nucleation easily occurs between the moving adatoms resulting in more smaller-size islands. In contrast, at the lower pulse intensities, nucleation event occurs preferentially between the single adatom and existing islands rather than forming new islands, and therefore the average island size becomes larger in this case. Additionally, our results show that substrate temperature plays an important role in film growth. In particular, it can determine the films shape and weaken the effect of pulse intensity on film growth at the lower temperatures by controlling the mobility rate of atoms. Our results can match the related theoretical and experimental results.     

甲酰胺与肌醇在氯化钠水溶液中的焓相互作用

应用等温流动微量热法测定298.15 K时甲酰胺与肌醇分子在不同浓度氯化钠水溶液中的混合过程焓变及其稀释焓, 根据McMillan-Mayer理论关联得到各级异系焓相互作用系数(h_xy, h_xxy及h_xyy). 结果表明, 甲酰胺与肌醇分子在氯化钠水溶液中的异系焓对相互作用系数h_xy均为负值, 并且随着氯化钠浓度的增加, h_xy的绝对值逐渐减小.     

Host–Guest Complexation of <Emphasis Type="Italic">β</Emphasis>-, <Emphasis Type="Italic">γ</Emphasis>-Cyclodextrin with Alkyl Trimethyl Ammonium Bromides in Aqueous Solution

As a continuation of our previous investigation, interactions between cyclodextrin (β-CD), γ-cyclodextrin (γ-CD) and alkyl trimethylammonium bromides in aqueous solutions have been studied with titration calorimetry and ¹H NMR at 298.15 K. The results are discussed in terms of the amphiphilic interaction of CD with surfactants and the iceberg structure formed by water molecules existing around the hydrophobic tail of surfactant molecules. The stoichiometry of the β-CD–surfactant system is 1:1 whereas that of the γ-CD–surfactant system is 1:2. The corresponding formation enthalpy (negative) of the complexes of the two systems decreases with an increase in the number of carbon atoms (n) in hydrophobic chain of surfactant molecule, C _n H_2n+1, whereas the entropy increases with the enlargement of n.     

Enthalpies of Dilution of D-p-Hydroxyphenylglycine in Buffer Solutions at Different pH

The effect of pH on the dilution enthalpies of D-p-hydroxyphenylglycine in phosphate buffer solutions has been investigated by isothermal titration microcalorimetry at 298.15 K. The corresponding homogeneous enthalpic interaction coefficients have been calculated according to the excess enthalpy concept. The results show that the enthalpies of dilution of D-p-hydroxyphenylglycine in phosphate buffer solutions at different pH are all positive. The overall trend is that enthalpies of dilution become more positive with an increase of pH, but there is a minimum of the enthalpy of dilution at pH = 7.0. The enthalpic pair interaction coefficients, h ₂, all have negative values. The results are interpreted from the point of view of solute-solute and solute-solvent interactions involved in the solvent effects.     

D-甘露醇与D-山梨醇在氯化钠水溶液中的稀释焓

应用等温流动微量热法测定了298.15 K时互为旋光异构体的D-甘露醇与D-山梨醇在不同浓度的氯化钠水溶液中的稀释焓, 利用 McMillan-Mayer 理论计算了D-甘露醇与D-山梨醇在不同浓度的氯化钠水溶液中的焓对相互作用系数. 结果表明, D-甘露醇和D-山梨醇在氯化钠水溶液中的焓对相互作用系数h2均为正值, h2的值随着氯化钠浓度的增加皆逐渐增大, 但D-山梨醇的焓对相互作用系数h2增大的速率[dh2 /dm(NaCl)]比 D-甘露醇的要大. 根据两多元醇分子构象结构的差异， 溶质-溶质相互作用和溶质-溶剂相互作用对结果进行了解释.     

不同结构的磷酸盐对凝胶体系中草酸钙晶体物相和相组成的影响

泌尿系结石的形成是一种病理性生物矿化过程，不同地区的结石发病率在3％～15％之间。且50％(美国)至80％(中国)的人会复发。结石中约70％以上为草酸钙(CaC2O4)结石。CaC2O4结石的形成与其热力学(过饱和度)和动力学(成核、生长和聚集)因素有关。由于结石患者尿液和正常人尿液中     

大孔Mo-Ni/Al2O3催化剂的催化裂化柴油加氢性能研究

采用三次纳米自组装合成法,制备了一种以二次纳米自组装Al₂O₃为主体的大孔主客体催化剂FA-40,具有0.78cm³·g^-1的孔容、114m₂·g^-1的比表面积、27nm的平均孔径、6.0nm和40nm的双峰孔结构、孔分布在10~100nm高度集中、低堆积密度为0.56g·cm^-3、活性金属含量高达35.70%。XRD和TEM分析结果显示,活性金属以直径小于2nm的微晶态纳米粒子形式均匀分散于主体表面。采用劣质催化裂化柴油进行20h加氢实验评价,反应趋于稳定时,FA-40的脱硫、脱氮及芳烃饱和率分别达到94.4%、95.5%和67.9%,与F-5相比分别提高了20%、80%和140%。300h的长周期加氢实验表明,FA-40具有良好的加氢性能。     

基于自交联杂萘联苯聚芳醚阴离子交换膜制备及其物理化学性质

以氯甲基杂环聚醚酮(CMPPEK)为原料,加入三乙胺进行铵化,并分别加入二乙烯三胺(DETA)和二乙胺(DEA),生成的仲胺基(或叔胺基)与邻近分子链氯甲基团进行自交联.经过制膜和离子交换反应,制备了DETA自交联杂萘联苯聚芳醚阴离子交换膜(DETA-QPPEK-OH)和DEA自交联杂萘联苯聚芳醚阴离子交换膜(DEA-QPPEK-OH).采用傅里叶变换红外(FTIR)光谱对制备自交联膜的化学结构进行表征.研究了DETA-QPPEK-OH和DEA-QPPEK-OH膜的理化性质,结果表明前者具有较低吸水率和更低溶胀度.通过研究DETAQPPEK-OH和DEA-QPPEK-OH膜的离子传导率随温度的变化规律,结果表明在80°C时其离子传导率分别达到0.060和0.028 S cm-1,表明本文制备的自交联膜具有较高离子传导率.此外还通过热重分析(TGA)对两类自交联膜的热稳定性进行了研究.     

大孔Mo-Ni/Al_2O_3催化剂的催化裂化柴油加氢性能研究

采用三次纳米自组装合成法,制备了一种以二次纳米自组装Al2O3为主体的大孔主客体催化剂FA-40,具有0.78 cm3·g-1的孔容、114 m2·g-1的比表面积、27 nm的平均孔径、6.0 nm和40 nm的双峰孔结构、孔分布在10~100 nm高度集中、低堆积密度为0.56 g·cm-3、活性金属含量高达35.70%。XRD和TEM分析结果显示,活性金属以直径小于2 nm的微晶态纳米粒子形式均匀分散于主体表面。采用劣质催化裂化柴油进行20 h加氢实验评价,反应趋于稳定时,FA-40的脱硫、脱氮及芳烃饱和率分别达到94.4%、95.5%和67.9%,与F-5相比分别提高了20%、80%和140%。300 h的长周期加氢实验表明,FA-40具有良好的加氢性能。     

Simultaneous Magneto-Optical Trapping of Fermionic ^40K and Bosonic ^87Rb Atoms

We report on simultaneous magneto-optical trapping of fermionic ^40K and bosonic 87Rb atoms. This trap is the first step towards quantum degenerate fermi gas ^40K. Laser lights for the two-species magneto-optical trap （MOT） are generated from diode lasers and tapered amplifier. The enriched ^40K dispenser is utilized in the experimental setup. We obtain up to 10^7 -10^8 ^40K and 10^8 -10^9 ^87Rb atoms respectively in the steady-state single-species MOT.