Microcalorimetric investigation of the toxic action of Cr(VI) on the metabolism of Tetrahymena thermophila BF5 during growth

Tetrahymena thermophila BF5 produce heat by metabolism and movement. Using a TAM air isothermal microcalorimeter, the power-time curves of the metabolism of T thermophila BF5 during growth were obtained and the action on them by the addition of Cr(VI) were studied. The morphological change with Cr(VI) coexisted and biomass change during the process of T thermophila BF5 growth were studied by light microscope. Chromium has been regarded as an essential trace element for life. However, hexavalent chromium is a known carcinogen, mutagen, cytotoxicant and strong oxidizing agent. Cr(VI) of different concentration have different effects on T thermophila BF5 growth with the phenomenon of low dose stimulation (0-3 x 10(-5) mol L-1) and high dose inhibition (3 x 10(-5) to 2.4 x 10(-4) mol L-1). The relationship between the growth rate constant (k) and c is a typical U-shaped curve, which is a characteristic of hormesis. T thermophila BF5 cannot grow at all when the concentration of Cr(VI) is up to 2.4 x 10(-4) mol L-1. The microscopic observations agree well with the results obtained by means of microcalorimetry. And T thermophila BF5 had obviously morphological changes by the addition of Cr(VI). (c) 2006 Elsevier B.V. All rights reserved.

Oscillatory change of SR-protein kinase activities during oocyte maturation meiosis in fish

The SR-protein kinase activity was analyzed and the cytological changes were observed during oocyte maturation in bisexual transparent color crucian carp ( Carassius auratus color variety). The results revealed that the SR-protein kinase activity was sensitive to the artificially induced spawning hormones, and the change of oscillatory activity was similar to that of the maturation-promoting factor (MPF) kinase that regulates meiotic cell cycle in fish.

Donor-donor binding in In2O3: Engineering shallow donor levels

Using first-principles band structure methods, we investigate the interactions between different donors in In2O3. Through the formation energy and transition energy level calculations, we find that an oxygen-vacancy creates a deep donor level, while an indium-interstitial or a tin-dopant induces a shallow donor level. The coupling between these donor levels gives rise to even shallower donor levels and leads to a significant reduction in their formation energies. Based on the analysis of the PBE0-corrected band structure and the molecular-orbital bonding diagram, we demonstrate these effects of donor-donor binding. In addition, total energy calculations show that these defect pairs tend to be more stable with respect to the isolated defects due to their negative binding energies. Thus, we may design shallow donor levels to enhance the electrical conductivity via the donor donor binding.

寡聚核苷酸与中药化学成分的相互作用研究

药物分子与生物分子的相互作用是分子水平上研究药物构效关系及药物筛选的基础。测定形成的非共价复合物及其稳定性是研究药物与靶分子相互作用的关键。单链和双链DAN与小分子的相互作用提供了包括抗癌、抗病毒及抗菌在内的大量治疗药物的作用机理。本论文选择合成了与SARS病毒和肿瘤相关的寡聚核昔酸靶分子，利用质谱高灵敏、专一性、快速、化学计量的特点，研究靶分子与临床上确有疗效的抗病毒、抗肿瘤中药中几大类化学成分的相互作用，探讨它们相互作用的规律，通过相互作用强度的比较，考察这些中药化学成分在抗病毒、抗肿瘤方面的可能活性。在单链寡聚核营酸靶分子（RNA，DNA）与皂昔类化合物的相互作用的研究中，首先建立了区分皂普类异构体的高分辨电喷雾质谱及多级串联质谱的分析方法，通过皂普准分子离子在CID谱中产生的碎片离子，可以提供皂昔昔元、糖基类型、糖链的连接位点，为类似化合物的异构体的区分提供了一个简捷、灵敏、准确的分析方法。考察了实验条件对单链寡聚核营酸靶分子（RNA，DNA）与中药化学成分相互作用的影响；在皂营、黄酮类化合物与单链寡聚核昔酸靶分子的作用研究中，发现非共价作用强度的大小与普元、糖链的结构有关，包括昔元的类型、轻基的数目、糖链的长短，以及糖链上甲基取代的位置。单链寡聚核普酸靶分子与生物碱的相互作用研究表明，相互作用亲和力的大小与生物碱的碱性强弱有关，季胺型生物碱的作用最强，如巴马汀、药根碱、小巢碱与靶分子均生成了较强的非共价复合物。与昔类、内酩、酚类等成分的相互作用同样与其结构密切相关。双链DNA与生物碱类化合物的相互作用研究发现，它们与生物碱的作用强度与双链DNA的AF碱基对富有或GC-碱基对富有有关，且复合物离子的CID断裂途径不同。生物碱化合物的结构不同，其作用强度存在较大差异。述研究结果建立了核昔酸与中药化学成分相互作用研究的软电离质谱方法，利用该方法的研究结果，可以为中药活性成分的初步筛选提供一条可以借鉴的途径。

AIGaN/GaN HEMTs Power Amplifier MIC with Power Combining at C-Band

A power amplifier MIC with power combining based on AlGaN/GaN HEMTs was fabricated and measured. The amplifier consists of four 10×120μm transistors. A Wilkinson splitters and combining were used to divide and combine the power. By biasing the amplifier at V_(DS) =40V, I(DS)= 0. 9A, a maximum CW output power of 41. 4dBm with a maximum power added efficiency (PAE) of 32. 54% and a power combine efficiency of 69% was achieved at 5. 4GHz.

AlGaInP LED with surface structure of two-dimensional photonic crystal

Some progress in the research of GaN based LED with photonic crystal structure has been made recently. Based on the photonic crystal's photonic band gap effect and photon grating diffraction principle, the extraction efficiency of LED with photonic crystal can be improved. In this paper, the restriction on AlGaInP LED's extraction efficiency is analyzed, and the photonic crystal is introduced in to the AlGaInP LED to improve the extraction efficiency. The theoretical analyses and the experiment results show that the output luminous intensity of LED with photonic crystal is improved by 16%, which results from some effect of the GaN based LED with photonic crystal.

40 Gbits/s all-optical clock recovery for degraded signals using an amplified feedback laser

All-optical clock recovery for the return-to-zero modulation format is demonstrated experimentally at 40 Gbits/s by using an amplified feedback laser. A 40 GHz optical clock with a root-mean-square (rms) timing jitter of 130 fs and a carrier-to-noise ratio of 42 dB is obtained. Also, a 40 GHz optical clock with timing jitter of 137 fs is directly recovered from pseudo-non-return-to-zero signals degraded by polarization-mode dispersion (PMD). No preprocessing stage to enhance the clock tone is used. The rms timing jitter of the recovered clock is investigated for different values of input power and for varying amounts of waveform distortion due to PMD.

etl workflow analysis and verification using backwards constraint propagation

University of Twente; Centre for Telematics and Information Technology; Netherlands Organisation for Scientific Research; Jacquard; Capgemini