一氧化氮对人肝癌细胞SMMC-7721辐射敏感性的增强效应

目的:观察一氧化氮对肿瘤细胞SMMC-7721辐射敏感性的作用效果。方法:实验于2005-06/09在兰州大学生命科学学院和中科院近代物理研究辐射医学实验室进行。处于对数生长期的肝癌细胞SMMC-7721,在用X射线照射前4h,换入含有0.1mmol/L硝普钠(一氧化氮的前体)的培养液,与对照组(不加硝普钠)一起,在200cGy/min的剂量率下,分别照射0,1,2,4,6,8Gy,换为正常培养液培养。用集落形成法计算细胞的存活率,用吖啶橙/溴乙啶双染法检测细胞的死亡情况,用流式细胞仪检测细胞周期。结果:①存活曲线细胞存活率随照射剂量增加而减少,硝普钠组细胞的克隆形成率低于对照组(2Gy时,P<0.01)。②细胞死亡百分率(坏死细胞与凋亡细胞总数/总细胞数):与照射剂量呈正相关,硝普钠组高于对照组(P<0.05)。对照组从(9.95±3.53)%(0Gy)逐渐升至(58.74±3.46)%(6Gy),而硝普钠组则从(18.53±12.02)%(0Gy)迅速升至(61.57±9.53)%(2Gy)。③细胞周期检测结果:对照组细胞经过X射线照射后,出现了G2/M期阻滞[从0Gy时(12.50±5.76)%逐渐增加到8Gy(40.36±2.74)%],而硝普钠组细胞在低剂量时主要表现为G0/G1期阻滞[0Gy:(16.06±7.19)%;2Gy:(17.93±0.92)%],而G2/M期阻滞仅在高剂量时明显[8Gy时为(50.10±3.93)%,P<0.05]。结论:经硝普钠产生的一氧化氮,通过与X射线协同作用,减少了肝癌细胞SMMC-7721的细胞存活率,促进细胞死亡,阻止细胞被阻滞至G2/M期,是一种有效的辐射增敏剂。

低速~(40)Ar~(17+)离子入射金属Be表面发射的近红外光谱线和X射线谱；Infrared Light and X-ray Emissions of ~(40)Ar~(17+) Impacting on Be Surface ；

用速度不同的(动能EK=272和357keV,速度v=1.14×106和1.72×106m/s)的高电荷态离子40Ar17+分别入射金属Be表面,同时测量这种相互作用过程中产生的近红外光谱线和X射线谱。实验结果表明,在低速范围内(速度小于玻尔速度vBohr=2.19×106m/s),速度较小的40Ar17+离子在到达金属的表面临界距离Rc到进入表面(2—3原子层)的进程中,形成了较多的高激发态Ar原子,其退激辐射较强的光谱线,进而验证了经典过垒模型。

齐40块蒸汽驱井组油层套管应力数值计算

将蒸汽驱汽窜形成的窜流温度场结果引入井筒应力分析模型中,利用有限元分析软件ANSYS进行了井筒在不同约束条件下的应力计算。计算结果表明,最大热应力都发生在套管内壁,且超过了N80套管的热弹性屈服极限,最大热膨胀都发生在温度变化过渡区,当油层上覆盖层为泥页岩时,其热应变达到了2%,远超过材料弹性极限应变0.3%,是诱发热采井套管变形损坏的主要原因。

Femtosecond optical Kerr effect study of Ge(10)AS(40)S(30)Se(20) film

The results of the femtosecond optical heterodyne detection of optical Kerr effect at 805 nm with the 80 fs ultrafast pulses in amorphous Ge10As40S30Se20 film is reported in this paper. The film shows an optical non-linear response of: 200 fs under ultrafast 80 fs-pulse excitation and the values of real and imaginary parts of non-linear susceptibility chi((3)) were 9.0 X 10(-12) and -4.0 X 10(-12) esu, respectively. The large third-order non-linearity and ultrafast response are attributed to the ultrafast distortion of the electron orbits surrounding the average positions of the nucleus of Ge, As, S and Se atoms. This Ge10As40S30Se20 chalcogenide glass would be expected as a promising material for optical switching technique. (c) 2005 Elsevier Ltd. All rights reserved.

Structural and optical properties of YAG : Ce3+ phosphors by sol-gel combustion method

High-quality Ce3+-doped Y3Al5O12 (YAG:Ce3+) phosphors were synthesized by a facile sol-gel combustion method. In this sol-gel combustion process, citric acid acts as a fuel for combustion, traps the constituent cations and reduces the diffusion length of the precursors. The XRD and FT-IR results show that YAG phase can form through sintering at 900 degrees C for 2 h. This temperature is much lower than that required to synthesize YAG phase via the solid-state reaction method. There were no intermediate phases such as YAlO3 (YAP) and Y4Al2O9 (YAM) observed in the sintering process. The average grain size of the phosphors sintered at 900-1100 degrees C is about 40 nm. With the increasing of sintering temperature, the emission intensity increases due to the improved crystalline and homogeneous distribution of Ce3+ ions. A blue shift has been observed in the Ce3+ emission spectrum of YAG:Ce3+ phosphors with increasing sintering temperatures from 900 to 1200 degrees C. It can be explained that the decrease of lattice constant affects the crystal field around Ce3+ ions. The emission intensity of 0.06Ce-doped YAG phosphors is much higher than that of the 0.04Ce and 0.02Ce ones. The red-shift at higher Ce3+ concentrations may be Ce-Ce interactions or variations in the unit cell parameters between YAG:Ce3+ and YAG. It can be concluded that the sol-gel combustion synthesis method provides a good distribution of Ce3+ activators at the molecular level in YAG matrix. (c) 2005 Elsevier B.V. All rights reserved.

长白山自然保护区北坡森林结构、植物多样性与碳储量40余年的变化

长白山自然保护区始建于1960年，位于北坡的红松针阔叶混交林森林生态系统是我国东北地区典型温带地带性森林植被之一，面临着全球气候变化和人类干扰的双重影响。 本研究以间隔43年的野外调查数据为基础，对1963年和2006年的长白山自然保护区北坡海拔800~1700m的森林植物群落进行对比分析，得到该区域的森林结构、植物多样性与碳储量的变化特点，讨论森林动态变化与人类活动、气候变化的关系，评价长白山自然保护区的保护效果： 对长白山北坡森林沿海拔梯度的森林结构和植物多样性的分析表明：群落的整体空间格局保存完好，植物种类变化不大，乔木层的建群种的种类基本不变，植物多样性与海拔高度呈负相关关系;林下层植物多样性受小环境影响，与海拔高度无明显相关。 以红松（Pinus koraiensis）针阔混交林、红松针叶混交林和云冷杉暗针叶林三种类型为单元分别研究各森林类型的多样性变化：α多样测度选择物种丰富度、Shannon-Wiener和Pielou均匀度指数，较好体现了样地内发生的多样性变化，灌木层和草本层多样性明显下降，一些稀有种和药用物种消失，红松等原优势物种有衰退趋势，阔叶树比例增大;β多样性测度选取Cody指数，体现出海拔梯度上的植被空间格局细节变化，演替层特别是阔叶树的物种更替变化有向高海拔移动的趋势。 对森林生态系统各层次碳储量进行估算：乔木层和灌木层采用维量法，对灌木层自建生长回归方程;草本层、枯枝落叶层采取收获法;植物细根采取根钻法;土壤采取土壤深度加权法。碳密度估算结果都与前人研究结果相似。各类型植被碳库总碳密度都达到170 t/hm2，远远高于国内平均森林植被碳库密度值44.9 t/hm2。 乔木层43年来的碳储量变化都无显著性差异，但仍表现出：阔叶树种碳储量上升，特别在高海拔类型这种变化更加明显;针叶树种碳储量在暗针叶林内大幅下降;树干的碳库分配比例都有所减少，表明植被碳库正存在向不稳定性方向发展的趋势。针阔混交林和暗针叶林的土壤碳储量，与植被碳库出现相反的变化趋势，整体碳库保持在一个相对平衡的状态。 推测造成这种变化的原因是：禁止砍伐等保护措施的实施，基本保存了乔木层垂直分布格局，而气候变暖使阔叶树种比例大幅增加，采集松籽等人类生产及旅游活动对林下层植被影响破坏较大。提议加强保护区内管理力度和规划，以减缓长白山北坡森林群落的不稳定变化趋势。

Meat and bone meal replacement in diets for juvenile gibel carp (Carassius auratus gibelio): effects on growth performance, phosphorus and nitrogen loading

A 11-week growth trial was conducted in a flow-through system with juvenile gibel carp Carassius auratus gibelio to evaluate the effects of gradual replacement of fish meal (FM) by meat and bone meal (MBM) on growth performance, phosphorus (P) and nitrogen (N) loading. Six isonitrogenous (crude protein: 410 g kg(-1)) and isoenergetic (gross energy: 18 kJ g(-1)) diets were formulated. FM was used as the control protein. In the other five diets, 20, 40, 60, 80 and 100% FM protein was substituted with MBM20, MBM40, MBM60, MBM80, MBM100, respectively. Total P content in the diets ranged from 16.0 to 28.3 g kg(-1) and the available P was 5.0-6.6 g kg(-1). The results showed that the best growth was achieved with fish fed on the control diet and MBM20. Final body weight, weight gain, feed efficiency, protein retention efficiency and energy retention efficiency decreased with increased dietary MBM. No significant differences were found in the feeding rate and hepatosomatic index between the groups. Apparent digestibility coefficient (ADC) of dry matter, protein and P decreased with increase in dietary MBM, while there were no significant differences in the ADC of energy. P and N retention decreased linearly while P and N loading increased linearly with the increased dietary MBM levels. No significant differences were observed in the activity of alkaline phosphatase, aspartate aminotransferase and alanine aminotransferase, as well as pyruvate kinase in liver or in serum. Total superoxide dismutase activity in MBM20 was significantly higher than that of MBM100.

40 Gb/s 光电探测器小信号测试法和大信号测试系统研究

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40-Gb/s Low Chirp Electroabsorption Modulator Integrated With DFB Laser

A 40-Gb/s monolithically integrated transmitter containing an InGaAsP multiple-quantum-well electroabsorption modulator (EAM) with lumped electrode and a distributed-feedback semiconductor laser is demonstrated. Superior characteristics are exhibited for the device, such as low threshold current of 20 mA, over 40-dB sidemode suppression ratio at 1550 nm, and more than 30-dB dc extinction ratio when coupled into a single-mode fiber. By adopting a deep ridge waveguide and planar electrode structures combined with buried benzocyclobutene, the capacitance of the EAM is reduced to 0.18 pF and the small-signal modulation bandwidth exceeds 33 GHz. Negative chirp operation is also realized when the bias voltage is beyond 1.6 V.

40-GHz wavelength tunable mode-locked SOA-based fiber laser with 40-nm tuning range

A 40-GHz wavelength tunable mode-locked fiber ring laser based oil cross-gain modulation in a semiconductor optical amplifier (SOA) is presented. Pulse trains with a pulse width of 10.5 ps at 40-GHz repetition frequency are obtained. The laser operates with almost 40-nm tuning range. The relationship between the key laser parameters and the output pulse characteristics is analyzed experimentally.

基于CLIGEN和GCM模型预测未来40年黄土丘陵沟壑区的气候变化——以安塞为例

为预测3种温室气体排放情景(A2、B2和GGa1)下未来40年黄土丘陵沟壑区的气候变化,利用安塞试验站1986—2003年的气候观测资料以及1986—2049年GCM(HadCM3)栅格数据,通过空间转换和时间转换,利用CLIGEN和GCM模型,预测未来40年以安塞为代表的黄土高原丘陵沟壑区的气候变化。结果表明:与当前条件相比,到2049年,A2、B2和GGa1 3种情景下预测的降雨量分别增加37%、22%和12%;3种情景下预测的最大月均降雨量出现在夏季;到2049年,A2、B2和GGa1 3种情景下预测的月均最低气温和月均最高气温皆增加,但差异不明显,年均最低气温和年均最高气温分别增加1.41~1.56℃和0.92~1.57℃。