Fabrication and Magnetic Properties of Co-Doped TiO2 Powders Studied by Nuclear Magnetic Resonance

Co0.04 Ti0.96O2 powders are fabricated by sol-gel method. The structure and magnetic properties are investigated under different annealing conditions systematically with emphasis on the influence of oxygen pressure. Pure anatase structure was acquired for all the samples annealed at 450℃ for one hour. The samples annealed in air exhibit evident room-temperature ferromagnetism (RTFM) with a small magnetic moment of 0.029μB per Co atom and coercivity Hc of 26 Oe, while the samples annealed in vacuum have strong RTFM with a larger magnetic moment of 1.18μB per Co atom and Hc of 430 Oe. The zero-field spin echo nuclear magnetic resonance spectrum of ^59Co is obtained to prove the existence of Co dusters in the latter samples, implying that the Co dusters are responsible for the strong RTFM in the samples annealed in vacuum. No Co cluster could be observed using both XPS and NMR techniques in the samples annealed in air, implying that the RTFM found in these sample sis intrinsic.     

加强学法指导 探讨复习新路

加强学法指导探讨复习新路王新（山东省高密市第三中学２６１５１９）近几年，数学高考发扬稳定的传统，创新的风格，考能力的特色，命题正越来越有利于高校选拔有学习潜能的优秀新生，突出试题的选拔功能，同时也为中学数学教学以及教研教改，提供了一个深层次的探究课题...     

超高效液相色谱-串联质谱法测定莲藕、莲叶、莲子、田泥与田水中12种农药残留

建立了莲藕、莲叶、莲子肉、莲子壳、田泥和田水中12种农药残留的分析方法。固体样品采用乙腈-水混合提取,氯化钠盐析后离心,分取乙腈提取液过Pesti Carb固相萃取柱净化洗脱,水样采用C18固相萃取柱直接富集净化洗脱,洗脱液浓缩定容后经超高效液相色谱-串联质谱(UPLC-MS/MS)基质外标法定量,并对12种农药的质谱裂解、基质效应进行了探讨。12种农药在0. 005(0. 010)~2. 500 mg/L范围内均呈线性关系,相关系数(r~2)大于0. 97;在低、中、高加标浓度下,莲叶、莲藕、莲子肉和莲子壳中12种化合物的平均加标回收率(A. R.)为75. 6%~116%,相对标准偏差(RSD)为1. 3%~25. 1%;田泥中除咪鲜胺之外,其余化合物的A. R.为64. 6%~104%,RSD为0. 9%~9. 5%;田水中除噻虫胺在低浓度、咪鲜胺和茚虫威在中、高加标浓度下的A. R.70%外,其余化合物的A. R.为71. 2%~101%,RSD为0. 9%~16. 9%。除田水中噻虫胺外,其余方法定量下限均不大于0. 01 mg/kg和0. 1μg/L。采用该法进行了莲藕田撒施10%异草松·异丙甲草胺·扑草净颗粒剂后的最终残留试验,结果表明:以有效成分剂量630 g a. i./ha和945 g a. i./ha施用1次后,异草松和异丙甲草胺在莲藕、莲子和莲叶中均无残留,扑草净在莲藕、莲子壳、莲子肉和莲叶样品中的残留量分别不超过0. 022、0. 166、0. 012、0. 181 mg/kg。     

引入Sb降低CZTS硒化温度的研究

采取直接在Cu_2ZnSnS_4(CZTS)驱体溶液中溶解锑基化合物的方法于CZTS中引入Sb,探究了不同浓度Sb的引入对于CZTS薄膜太阳能电池的影响.研究结果表明Sb的引入能够显著降低CZTS的硒化温度至470℃.同时XRD和SEM表征测试结果表明随着Sb引入浓度的增加,低温下制备的CZTS薄膜的结晶性得到了逐渐的增强.EQE测试结果表明Sb引入之后CZTS薄膜太阳能电池的光响应也得到了提升,最终能够大幅提升CZTS薄膜太阳能电池的各项光伏性能参数,在4%(物质的量分数) Sb的引入量时得到了7.72%的效率.     

薄层色谱法检测磺胺二甲基嘧啶中杂质

建立限量检测磺胺二甲基嘧啶中杂质的方法.用薄层色谱法,使用两种展开剂系统分步同向展开对样品中的杂质进行检测.本法能简便有效地检测出磺胺二甲基嘧啶中各种可能杂质.     

Surface plasmon enhanced photoluminescence in amorphous silicon carbide films by adjusting Ag island film sizes

Ag island films with different sizes are deposited on hydrogenated amorphous silicon carbide (α-SiC:H) films, and the influences of Ag island films on the optical properties of the α-SiC:H films are investigated. Atomic force microscope images show that Ag nanoislands are formed after Ag coating, and the size of the Ag islands increases with increasing Ag deposition time. The extinction spectra indicate that two resonance absorption peaks which correspond to out-of-plane and in-plane surface plasmon modes of the Ag island films are obtained, and the resonance peak shifts toward longer wavelength with increasing Ag island size. The photoluminescence (PL) enhancement or quenching depends on the size of Ag islands, and PL enhancement by 1.6 times on the main PL band is obtained when the sputtering time is 10 min. Analyses show that the influence of surface plasmons on the PL of α-SiC:H is determined by the competition between the scattering and absorption of Ag islands, and PL enhancement is obtained when scattering is the main interaction between the Ag islands and incident light.     

Influence of substrate bias voltage on the microstructure of nc-SiOx:H film

Amorphous silicon oxide containing nanocrystalline silicon grain(nc-SiO_x:H) films are prepared by a plasmaenhanced chemical vapor deposition technique at different negative substrate bias voltages.The influence of the bias voltage applied to the substrate on the microstructure is investigated.The analysis of x-ray diffraction spectra evidences the in situ growth of nanocrystalline Si.The grain size can be well controlled by varying the substrate bias voltage,and the largest size is obtained at 60 V.Fourier transform infrared spectra studies on the microstructure evolutions of the nc-SiO_x:H films suggest that the absorption peak intensities,which are related to the defect densities,can be well controlled.It can be attributed to the fact that the negative bias voltage provides a useful way to change the energies of the particles in the deposition process,which can provide sufficient driving force for the diffusion and movement for the species on the growing surface and effectively passivate the dangling bonds.Also the larger grain size and lower band gap,which will result in better photosensitivity,can also be obtained with a moderate substrate bias voltage of 60 V.     

一种新型介孔空腔二氧化硅纳米微球的制备与缓释行为

本文用十六烷基三甲基溴化铵(CTAB)作为试剂,通过软模板法合成介孔二氧化硅,利用在合成过程中,由伪莫尔转动所引起的微粒内部的大量缺陷,通过溶剂抽提,形成了具有空腔结构的介孔二氧化硅纳米微球.采用透射电子显微镜(TEM)、X射线粉末衍射仪(XRD)、N2吸附-脱附等手段对产物的形貌和结构进行了详细的表征.并以溴甲酚绿作为目标物,通过改变压强和温度,调节溴甲酚绿进入空心SiO2微球中的不同部位,对所制备的空腔介孔二氧化硅微球进行染料的装载和释放试验.结果显示该微球腔壁具有可渗透性和缓释性,而且在负压蒸发溶剂的情况下可以得到较高的药物负载量和极大地提高缓释性能.     

过氧化苯甲酰的光敏电荷转移分解反应及引发甲基丙烯酸甲酯的聚合

The mechanism of photosensitized decomposition of benzoyl peroxide by several anthracene derivatives has been studied. It comfirms that the photosensitized process is carried out by electron transfer.It is discovered that benzoyl peroxide can be decomposed by sensitizer of different anthracene derivatives which are used either electron donor or acceptor and the active radical which produces in this reaction can initiate the polymerization of MMA. It is considered that the BPO with positive charge in the charge transfer complex is easier to decompose into radical than that with negative charge,so the rate (Rp) of polymerzation of MMA in-itiated by the system of DCA/BPO has higher value than others.     

以构象概念为主线的高分子物理教学实践

提出以构象概念作为教学主线,论述了构象概念的意义以及构象概念与力学状态、橡胶弹性、取向态、流变性和凝聚态的内在关系。