折反射周视系统研究进展与展望

折反射周视系统作为近十几年发展起来的一种新型周视视觉实现形式,相比相机旋转扫描、多相机图像拼接和鱼眼镜头大视场成像等常规方法,在小型化、结构灵活性、成本和实时性方面具有优势。本文综述了折反射周视系统的成像模型、系统标定、畸变校正和全视场清晰成像等基本问题研究状况,讨论了折反射周视系统在红外成像和立体视觉领域的扩展应用研究现状,最后总结了目前存在的问题,并提出未来折反射周视成像系统将围绕非单视点成像模型、提高空间分辨力的方法和处理算法实时实现开展研究。     

Possible ferromagnetism in MgO

We study the impact of vacancies on the magnetism of MgO and TiO₂ nanoparticles, and develop fist-principle calculations to ascertain the origin of the induced polarization. Theoretically, we expect ferromagnetism only for the case of MgO with cation defects. Experimentally, we observed a small magnetic signal probably due to imperfections in the lattice order, perhaps at the nanoparticles surface.     

Enhanced general analytical equation for the kinetics of the thermal degradation of poly(lactic acid) driven by random scission

An enhanced general analytical equation has been developed in order to evaluate the kinetic parameters of the thermal degradation of poly(lactic acid) (PLA) at various linear heating rates and at constant rate conditions. This improvement consisted of replacing the n-order conversion function by a modified form of the Sestak-Berggren equation f(α) = c(1?α)ⁿα^m, which led to better adjustment of experimental data, and also adequately represented the conventional mechanisms for solid-state processes. The kinetic parameters so obtained have been compared to those determined by conventional differential and isoconversional methods. Given that the thermal degradation of PLA has been argued to be caused by random chain scission reactions of ester groups, the conversion function (α) = 2(α^1/2?α), corresponding to a random scission mechanism, has been tested.     

类产碱假单胞菌XW-40发酵-生物转化级联产生D-脯氨酸

建立了一个新颖的用于产生D-脯氨酸的发酵-生物转化过程.发酵过程中,以DL-脯氨酸为发酵前体,类产碱假单胞菌XW-40利用L-对映体诱导产生脯氨酸脱氢酶,D-对映体完全保留.在最优条件下,发酵阶段产生6 g/L D-脯氨酸.生物转化过程中,细胞不经分离,发酵液直接作为反应介质.采用分批补料策略实现DL-脯氨酸中L-对映体的转化.DL-脯氨酸单批补料浓度为10 g/L,补料次数达到5批.通过发酵和生物转化的级联,累积的D-脯氨酸浓度达到31 g/L,ee99%.推测了生物转化过程中D-脯氨酸产生的反应机理.     

PQQ对四氯化碳和乙醇引起大鼠肝损伤的保护作用

将大鼠分成5组,采用灌胃方式,连续14d分别灌入PQQ－水溶液,PQQ-乙醇溶液,乙醇溶液和生理盐水溶液（阴性和阳性对照两组）,尔后,除阴性对照组外,均灌入CCL4,检测结果表明：PQQ可明显降低大鼠血清中GPT,GOT以及肝组织中MDA的含量,可减少轻肝细胞水变性,脂肪变性和肝细胞坏死的程度,由此说明：PQQ对CCl4和乙醇引起的肝损伤有一定的保护作用。     

Quantification of sterols, 5α- and 5β-stanols in sewage sludge, manure and soils amended with these both potential fertilizers

A method for the quantitative determination of sterols, 5α- and 5β-stanols is proposed to characterize the lipid fraction of two potential organic fertilizers, like sewage sludge and manure, as well as soils amended by them. It was possible to determine the kind of fertilizer added to the soil. Further studies were conducted to determine the accumulative effects of steroids in soils treated with manure and different doses of sewage sludge.     

主链含噁二唑的离子传导型聚对苯乙炔衍生物的合成及发光性能

通过共聚合将噁二唑结构单元引入苯乙炔(PPV)主链,以改进电子注入与传输性能;用离子传导型的聚氧乙烯(PEO)链作为高分子的侧链.用该种聚合物制作的发光二极管(LED)与不含噁二唑的同类结构的共轭聚合物相比,性能明显提高,并制作了发光电池(LEC),对其性能进行初步研究.     

Collective oscillations in quantum rings: A broken symmetry case

We present calculations within density functional theory of the ground state and collective electronic oscillations in small two-dimensional quantum rings. No spatial symmetries are imposed to the solutions and, as in a recent contribution, a transition to a broken symmetry solution in the intrinsic reference frame for an increasingly narrow ring is found. The oscillations are addressed by using real-time simulation. Conspicuous effects of the broken symmetry solution on the spectra are pointed out. Received 6 April 2000 and Received in final form 9 June 2000     

聚次甲基蓝膜的生长及性质

在铂电极和金电极上,次甲基蓝在低电位 0～－ 0.5 V范围内的氧化还原已有报导,它在 － 0.2 V处有可逆的氧化还原峰 [1,2].近来,已将次甲基蓝的氧化升高至 1.2 V（ vs Ag/AgCl参比电极）, 在玻炭电极上形成一层聚合物膜 [3],这种聚合物可被用来固定葡萄糖氧化酶制成葡萄糖生物传感器 [3].在扫描电位为－ 0.6～ 1.0 V（ vs SCE）范围内, 聚次甲基蓝膜的生长已通过电化学石英晶体微天平技术得到了证实,同时证实了,在氧化还原过程中阴离子能够在聚次甲基蓝膜中掺杂和去掺杂 [4].聚次甲基蓝在 pH为 2.0至 8.0范围内具有很好的电化学…     

Iron oxide nanoparticles hosted in silica aerogels

The investigated hybrid materials consist of non-agglomerated iron oxide particles hosted in silica aerogels. The composite material can be produced as a monolith, in any shape, and with different dilutions of the iron oxide phase. Two sol–gel chemistry routes have been followed: a solution of Fe(NO₃)₃·9H₂O has been added either to the silica gel or to the initial sol; in the latter, the iron salt provided the water required for the gel polymerisation. To obtain monolithic aerogels, the gels were dried by hypercritical solvent evacuation. On the other hand, some gels were dried by slow and controlled evaporation of the solvent, resulting in xerogels. Several heat treatments have been performed and the iron oxide particle phase, growth mechanism and crystallinity have been analysed. The composite materials were characterised by means of X-ray diffraction, M?ssbauer spectrometry and superconducting quantum interference device magnetometry. It was observed that the particle sizes (in the nanometre range) and the thermal stability of the iron oxide phases strongly depend on the preparation method that determines the microstructure of the host material. Consequently, the magnetic properties of the nanoparticles can be controlled via synthesis conditions, matrix properties and thermal treatments. Received: 5 March 2001 / Accepted: 16 June 2001 / Published online: 30 August 2001