原子吸收光谱法测定内蒙古典型草原长期施用有机肥对土壤锰组分影响

采用改进的BCR连续提取,利用原子吸收光谱法测定了内蒙古草地施用羊粪试验11年后土壤中Mn组分。试验设置5个处理,分别施干羊粪0,50,250,750和1 500 g·m-2·yr-1。结果表明,以四步加和法与强酸直接消煮法测定的全Mn含量作为回收率,各处理回收率为91.4%～105.9%,加标回收率为97.2%～102.9%。长期大量施有机肥可提高0～5 cm土层植物可利用的交换态Mn含量47.89%,但还原态Mn和全Mn含量显著下降。施肥对0～5 cm土层Mn形态影响大于5～10 cm土层。研究结果对于土壤微量元素形态测定及草地养分管理具有一定的参考价值。     

Ag掺杂对p型Pb0.5Sn0.5Te化合物热电性能的影响规律

采用熔融缓冷技术制备了不同Ag掺杂量的p型Ag_x(Pb_0.5Sn_0.5)_1-xTe化合物,系统地研究了Ag掺杂对所得材料的相组成、微结构及其热电传输性能.Ag的掺入显著增加了材料的空穴浓度,但是材料的空穴浓度远小于Ag作为单电子受主时理论空穴浓度,且在掺杂量为5%时未出现任何第二相,这表明Ag在可能进入晶格间隙位置而作为电子施主,起到补偿作用.随着Ag掺杂量的增加,样品的电导率逐渐增加,而Seebeck系数表现出复杂的变化趋势:在低于450 K时逐渐增加,而在温度大于450 K时逐渐降低,这主要源于材料复杂的价带结构.由于空穴浓度的优化和重空穴带的主导作用,1%Ag掺杂样品获得最大的功率因子,在750 K可达2.1 mW.m^-1.K^-2.此外,Ag的掺入引入的点缺陷大幅散射了传热声子,使得晶格热导率随着Ag掺量的增加逐渐降低.结果1%Ag掺杂样品在750 K时获得了最大的热电优值ZT=1.05,相比未掺样品提高了近50%,这一数值同商业应用的p型PbTe材料的性能相当.但是Sn取代显著降低了有毒重金属Pb的用量,这对PbTe基材料的商业化应用及其环境相适性具有重要意义.     

Efficient continuous-wave eye-safe region signal output from intra-cavity singly resonant optical parametric oscillator

We report an efficient continuous-wave (CW) tunable intra-cavity singly resonant optical parametric oscillator based on the multi-period periodically poled lithium niobate and using a laser diode (LD) end-pumped CW 1064 nm Nd:YVO₄ laser as the pump source. A highly efficiency CW operation is realized through a careful cavity design for mode matching and thermal stability. The signal tuning range is 1401-1500 nm obtained by varying the domain period. The maximum output power of 2.2 W at 1500 nm is obtained with a 17.1 W 808 nm LD power and the corresponding conversion efficiency is 12.9%.     

CMOS电路总剂量效应最劣偏置甄别

采用电路分析和解析建模方法研究了CMOS电路中甄别总剂量效应最劣辐照与测试偏置的问题。通过引入小规模模拟电路和数字电路的例子进行具体分析,获取了不同电路的最劣偏置情况。对于数字电路,引入了敏感因子的概念用于定量计算不同辐照与测试偏置组合下电路的总剂量效应敏感程度。利用实测数据或电路仿真结果对甄别结果进行了一一验证,得到相一致的结论,证明了该研究思路的正确性。     

中温固体氧化物燃料电池的基本性质测量

介绍了固体氧化物燃料电池的工作原理,测量了中温薄膜固体氧化物燃料电池的开路电压、放电曲线及功率曲线,并分析了电池内阻随电流密度的变化.     

Enhancement of upconversion luminescence of YAlO3:Er3+ by Gd3+ doping

The upconversion luminescences of YAlO3:Er3+ phosphor co-doping with different Gd3+ concentrations are investigated under the excitation of 980- and 532-nm diode lasers. A near ultraviolet upconversion emission at 410 nm is observed in YAlO3 under 532-nm excitation. Moreover, the inactive Gd3+ ions can improve the upconversion intensity efficiently in a certain range of concentration. Under 980-nm excitation, the visible upconversion emissions at 546 and 646 nm are enhanced by about 10 and 8 times at the Gd3+ concentration of 40%, respectively. The upconversion emission at 410 nm under 532-nm excitation is also enhanced by 7 times. The substitution of Gd3+ ions for Y3+ sites changes the local symmetry of Er3+, leading to the improvement of upconversion efficiency.     

基于动态溶胀法制备中空聚合物微球

以表面带正电荷的m级聚苯乙烯微球为种子,经过甲苯、二乙烯基苯溶胀,聚合与包覆等过程制备了直径约5 m的中空聚合物微球。研究了溶剂类型、溶剂用量对动态溶胀法制备的中空聚合物微球粒径、分布和结构的影响,讨论了中空聚合物微球的形成机理。结果表明:添加一定量甲苯、二甲苯等挥发性溶剂是动态溶胀法形成中空聚合物微球的前提;甲苯用量越多,溶胀后形成的中空结构越明显,孔径越大;选择低溶解性的二甲苯溶剂更有利于中空结构的形成。     

Transfection using hydroxyapatite nanoparticles in the inner ear via an intact round window membrane in chinchilla

Hydroxyapatite nanoparticles (nHAT) are known to have excellent biocompatibility, and have attracted increasing attention as new candidates of non-viral vectors for gene therapy. In our previous studies, nHAT carrying a therapeutic gene and a reporter gene were successfully transfected into the spiral ganglion neurons in the inner ear of guinea pigs in vivo as well as in the cultured cell lines, although the transfection efficiencies were never higher than 30%. In this study, the surface modification of nHAT with polyethylenimine (PEI) was made (PEI–nHAT, diameter = 73.09 ± 27.32 nm) and a recombinant plasmid carrying enhanced green fluorescent protein (EGFP) gene and neurotrophin-3 (NT-3) gene was constructed as pEGFPC2–NT3. The PEI modified nHAT and the recombinant plasmid was then connected to form the nHAT-based vector–gene complex (PEI–nHAT–pEGFPC2–NT3). This complex was then placed onto the intact round window membranes of the chinchillas for inner ear transfection. Auditory brainstem response (ABR) was tested to evaluate auditory function. Green fluorescence of EGFP was observed using confocal microscopy 48 h after administering vector–gene complexes. There was no significant threshold shift in tone burst-evoked ABR at any tested frequency. Abundant, condensed green fluorescence was found in dark cells on both sides of the crista and around the macula of the utricle. Scattered EGFP signals were also detected in vestibular hair cells, some Schwann cells in the cochlear spiral ganglion region, some outer pillar cells in the organ of Corti, and a few cells in the stria vascularis. The density of green fluorescence-marked cells was obviously higher in the vestibular dark cell area than in other areas of the inner ear, suggesting that vestibular dark cells may have the ability to actively engulf the nHAT-based vector–gene complexes. Considering the high transfection efficiency in the vestibular system, PEI–nHAT may be a potential vector for gene therapy of inner ear diseases, especially vestibular disorders, and deserves further study.     

菱形纤芯光子晶体光纤色散与双折射特性分析

针对光子晶体光纤多零色散点、高双折射的应用要求, 设计了一种新型结构的光子晶体光纤, 其纤芯由位于菱形四个角上的圆形空气孔组成. 通过有限元数值分析方法对该种结构光子晶体光纤的色散特性和双折射特性进行数值仿真, 得到色散与波长、色散与纤芯圆孔尺寸、双折射与波长、双折射与纤芯圆孔尺寸的关系. 研究结果表明:在满足光纤传输功率要求的条件下, 光纤的双折射在d₁<0.8 μupm 时的性能较好. 同时, 该种结构的光子晶体光纤在芯区直径满足d₁=0.4 μupm或 d     

High-power ultraviolet 278 nm laser from fourth-harmonic generation of a Nd:YAG laser in CsB3O5

We demonstrate a high-power UV 278 nm laser by fourth-harmonic generation (FHG) of a 1112 nm Nd:YAG laser in a nonlinear optical (NLO) crystal CsB3O5 (CBO) for the first time, to our best knowledge. A 30 W level diode-pumped Q-switched Nd:YAG laser at 1112 nm with beam quality factor M2=1.2 was used as the fundamental light source at a pulse width of 500 ns. With an LiB3O5 crystal, the 1112 nm laser was first frequency-doubled to 556 nm with an average output power of 13.5 W. It was then frequency doubled again in a CBO crystal to obtain the FHG output at 278 nm. The maximum average output power of the 278 nm laser is up to 1.5 W. The results demonstrated that CBO crystal is a promising NLO material for UV high-power lasers below 300 nm.