藻类叶绿素荧光对除草剂生物毒性响应特性的研究

以蛋白核小球藻、铜绿微囊藻、斜生栅藻为敏感藻,研究了莠去津、敌稗、敌草隆、灭草松四种除草剂及其混合剂对藻类光合特性的影响规律,实验同时确定了三种微藻荧光对除草剂的最佳响应时间。实验结果表明,除草剂显著降低了藻细胞类囊体膜中光系统Ⅱ的最大光合效率(Fv/Fm)、实际光合效率(Y(Ⅱ))、绝对电子传递速率(ETR)和光化学猝灭系数(qP),而非光化学猝灭系数(qN)呈现上升趋势,400 μg·L-1敌草隆使蛋白核小球藻Fv/Fm参数值下降了41%。实验选用的三种实验藻在四种除草剂单独和混合胁迫下均发生了不同程度的光抑制效应,表现出光合效率、电子传递速率、光合活性的降低和光保护能力的增强,藻类自身具有一定的光保护机制可以降低除草剂的影响。除草剂能够影响藻细胞叶绿素荧光强度,其中灭草松对蛋白核小球藻的影响最为显著,在400 μg·L-1灭草松影响下蛋白核小球藻的叶绿素荧光强度下降了44%。     

基于光诱导荧光技术的浮游植物光合作用活性原位测量方法

根据浮游植物在不同光照下的荧光诱导特性,研究了叶绿素荧光作为浮游植物光合作用探针的特点,提出了原位测量活体叶绿素荧光值Ft和Fm获取浮游植物光合作用活性的方法。以淡水湖泊浮游植物中的普通小球藻、铜绿微囊藻和梅尼小环藻为实验对象,将原位测量方法得到的数据和实验室水样荧光仪的测试结果进行对比分析,结果表明:普通小球藻、梅尼小环藻和铜绿微囊藻的两组测试结果之间的相关系数分别为0.977 8,0.867 8和0.776 8,研究为进一步实现水体浮游植物光合作用活性的快速连续原位测量提供了方法。     

基于色素特征荧光光谱的浮游植物分类测量方法

光合作用色素组成是浮游植物分类的重要依据。通过对蓝藻、绿藻、硅藻、甲藻和隐藻等5个门类浮游植物三维荧光光谱的差异性分析,提取了与叶绿素a、叶绿素b、叶绿素c、类胡萝卜素、藻蓝蛋白和藻红蛋白等光合色素相关的36个特征荧光光谱点,提出了基于色素特征荧光光谱的不同门类浮游植物分类测量方法。对铜绿微囊藻、小球藻、桅杆藻、光甲藻和卵形隐藻的实验结果表明:色素特征荧光光谱法对5种藻类纯种样品的测量误差分别为5.15%、5.63%、7.90%、4.85%、6.55%,对优势藻类(质量分数高于50%)的测量误差分别为7.96%、8.69%、5.44%、10.78%、15.57%,对劣势藻类(质量分数低于30%)的测量误差分别为18.29%、17.52%、20.01%、29.11%、20.14%,测量结果准确度达到了三维荧光光谱法水平,但数据量和计算时间仅是三维荧光光谱法的1.1%和2.2%,是一种快速有效的浮游植物分类测量方法。     

同步扫描荧光光谱对水体四种重金属离子毒性的研究

采用三维荧光光谱和Δλ=20nm同步扫描荧光光谱技术研究Hg2+,Cd2+,Cu2+,Zn2+胁迫作用下蛋白核小球藻(Chlorella pyrenoidosa)荧光光谱的变化情况,两种光谱技术得到了较为一致的结论:即胁迫作用96h后,蛋白核小球藻荧光中心处的荧光值显著降低,四种重金属离子对藻细胞光合系统的叶绿素a和叶绿素b造成了严重的破坏。进一步分析四种重金属离子浓度与由同步扫描荧光光谱得到的藻荧光猝灭效率I0/I的相关性可知:重金属离子的毒性与荧光猝灭效率I0/I呈正相关关系,均随重金属离子浓度和胁迫时间的增加而增强。对某一种重金属而言,同步扫描荧光光谱可实现藻细胞对该重金属毒性的评价。与三维荧光光谱相比,同步扫描荧光光谱具有耗时少、对特定荧光中心选择性高等优点,是研究水体有毒污染物毒性的有利工具。     

基于叶绿素荧光诱导动力学曲线的光合作用参数反演算法研究

快相叶绿素荧光诱导曲线中蕴含着丰富光合作用信息。该信息可以反映出植物的生存状态、病理以及受到胁迫时的生理变化趋势等多种信息。通过采集藻类荧光及诱导光信号, 拟合快相叶绿素荧光动力学曲线。基于最小二乘拟合方法,提出自适应最小误差逼近的方法对快相叶绿素荧光动力学曲线进行多元非线性回归拟合,实现F_o（固定荧光）、F_m（最大荧光产率）、σ_PSII（PSII的功能吸收截面）等细节参数的反演。实现了蛋白核小球藻光合作用参数反演,并实验了在Cu2+胁迫环境下,蛋白核小球藻的生理变化趋势。     

OJIP荧光动力学曲线J、I点特征时间确定方法

OJIP荧光动力学被广泛应用于藻类光合作用研究,而在常用的OJIP曲线分析中,常将J、I点的特征时间固定,忽略了藻类种类对J、I点特征时间的影响,这会造成J、I点荧光强度计算结果的偏差,直接影响测量结果的准确性。鉴于此,提出使用三级指数函数逼近OJIP曲线的方法动态获取J、I点的特征时间。不同藻种的J、I点的特征时间和二氯苯基二甲脲（DCMU）胁迫下J点特征时间实验的测试结果表明：所提方法能够有效获得不同藻类J、I点的特征时间,二形栅藻、蛋白核小球藻、普通小球藻和新月筒柱藻J点的特征时间分别为2.22,1.52,1.33,1.01 ms, I点的特征时间分别为28.80,27.15,29.90,15.28 ms,多次计算结果的相对标准偏差均小于10%,具有较好的一致性;在DCMU浓度（质量浓度）分别为10,20,40μg/L的毒性胁迫实验条件下,所提方法计算的普通小球藻的J点特征时间分别为1.25,1.18,1.10 ms,相对标准偏差为12.03%。此外,利用所提方法计算得到的光合活性参数V_J与DCMU浓度之间具有良好的毒性剂量-效应关系,相关性系数R^...     

快相与弛豫荧光动力学植物光合作用参数反演方法

根据生物膜能流理论和电子传递模型,结合快相与弛豫两种激发条件,对复杂的光合作用过程进行分析并简化计算,提出植物光合作用参数反演方法。利用滑动窗口斜率判定法确定最大荧光产率;利用线性最小二乘算法解析快相荧光过程获得光化学量子效率和功能吸收截面;利用离散迭代算法解析弛豫荧光过程获得质体醌平均还原时间常数。对对数生长期以及铜离子胁迫条件下的平裂藻和斜生栅藻进行实验测量,结果表明该方法反演结果具有良好的稳定性和重复性,光化学量子效率、功能吸收截面和质体醌平均还原时间常数的测量结果相对标准偏差分别为1.25%、1.50%和1.83%,其中光化学量子效率与脉冲振幅调制技术的测量结果线性相关系数达到0.9714。该方法为研究植物生理研究提供一种光学分析手段。     

基于多任务卷积神经网络的浮游藻类群落识别方法

针对混合浮游藻类群落离散三维荧光光谱特征识别,对比分析了简单卷积神经网络(PlainCNN)和文本卷积神经网络(TextCNN)模型对5种常见门类藻(铜绿微囊藻、斜生栅藻、菱形藻、楯形多甲藻和隐藻)混合数据的种类识别准确率及浓度测量精度。结果表明,在藻类独立识别及浓度回归分析中,PlainCNN模型对测试集的平均识别准确率和浓度输出结果的平均均方误差分别为90%和0.052,均优于TextCNN模型。为了同时实现混合藻类种类识别和浓度分析,基于PlainCNN模型提出了多任务卷积神经网络PlainCNN-MT模型。该模型对混合藻类种类识别的平均准确率提高至95%,浓度输出结果的平均均方误差降低至0.039,表明多任务卷积神经网络在浮游藻类群落识别与定量分析中更具优势。     

不同生境条件下藻蓝蛋白活体荧光光谱特性研究

蓝藻生物量检测技术发展是应对目前频繁发生的水华事件的重要环节。藻蓝蛋白作为蓝藻的特异性蛋白,在一定程度上比叶绿素更能准确反应自然水体中的蓝藻生物量,因而成为蓝藻生物量检测技术的重要指标。本文利用三维荧光光谱技术,以不同光照、不同生长期的铜绿微囊藻、鱼腥藻活体为研究对象,比较了单点法和包络法两种光谱解析方法的可靠性,探究了不同生境条件下的藻蓝蛋白活体荧光光谱特性。结果表明：(1)荧光光谱强度随生长期延长而增大;(2)采用包络法解析藻蓝蛋白特征荧光光谱的方法比单点法更为可靠;(3)在不同生境条件下,铜绿微囊藻藻蓝蛋白活体荧光激发波长基本保持614 nm、发射波长基本保持654 nm不变,鱼腥藻藻蓝蛋白活体荧光激发波长随生长期在610和620 nm之间波动减小,发射波长随生长期在650和660 nm之间波动增大。这种波动与藻种样品颗粒度大小和光谱扫描模式有关。该研究结果为发展蓝藻生物量活体荧光监测技术发展提供了实验基础。     

不同磷浓度培养条件下铜绿微囊藻高光谱特征研究

铜绿微囊藻(Microcystis aeruginosa)是国内湖泊蓝藻水华中的常见藻种,在实验室光照培养箱中对其进行培养,使用GER1500光谱仪在自然光照下采集藻液的光谱数据,研究了不同磷浓度培养基条件下铜绿微囊藻的生长规律以及培养周期内藻液的光谱变化特征,结果表明,其他条件相同情况下,低磷浓度(≤10μg.L-1)成为铜绿微囊藻生长繁殖的限制性因素,随着培养时间的不断增加,铜绿微囊藻藻液的光谱曲线在550,610,660,700～710,760nm附近等一些波段呈现出明显的变化特征。     

Hybrid Wavelength and Code Division Multiple Access in Optical Networks

A review of schemes for multiple access in fiber optic networks shows that a hybrid of wavelength and code division multiple access (WCDMA) combines the best features of both. In particular, the hybrid scheme retains the large information carrying capacity of wavelength division multiple access (WDMA) and flexibility of code division multiple access (CDMA). In this paper WDMA, optical CDMA (OCDMA), and WCDMA networks are discussed. In OCDMA networks, concept of incoherent and coherent coding including inverse decoding and matched filter is introduced. The delay performance of both WDMA and WCDMA networks, under the simple suboptimum access protocols based on cyclic search, is computed. It has been shown quantitatively that tuning delay significantly affects the delay performance of both WDMA and WCDMA networks. Futhermore, delay performance of WCDMA networks is always better than the WDMA networks for the same tuning delay, load, and number of users.     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Femtosecond Transform-Limited Pulse Generation by Compensating for the Linear Chirp of SPM Spectra in Dispersion Shifted Fibers

A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Theoretical analysis and simulation of conjugate heights for dual-conjugate AO system in lidar

A multi-conjugate adaptive optics （MCAO） can offer a possibility of widening field of view （FOV） characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle＇s expressions of two deformable mirrors （DMs） MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.     

Quick single-photon detector with many avalanche photo diodes working on the time division

Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.     

Research on beamforming method for dual-line array with space mismatch between the two line arrays

The performance of port/starboard discrimination of dual-line array will be seriously degraded when the space between the two line arrays of the dual-line array is mismatched. The directivity function of the delay-sum and delay-subtract beamforming is deduced and the port/starboard discrimination of the delay-sum and delay-subtract beamforming is also studied both under the ideal status and the status under which the space between the two line arrays of the dual-line array is mismatched. Analysis results show the delay-subtract beamforming has better performance of port/starboard discrimination. At last, the sea trial results demonstrate the theoretical results.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

Retrieval of ultraviolet skylight radiances and O3 slant column densities from balloon-borne limb spectrometer

With a novel light-weight and absolutely calibrated ultraviolet （UV） spectrometer, UV skylight radiances and O3 slant column densities are measured by balloon-borne limb measurements in Xinjiang area, China. UV skylight radiances measured at the height of 31 km are compared with the results from Modtran in the wavelength range from 290 to 420 nm. O3 slant column densities are derived from radiance spectra in the Huggins bands （320 - 335 nm） using differential optical absorption spectroscopy method. And the parameter exhibits a good correlation with the same value simulated by radiative transfer model （Tracy）. The O3 profile simultaneously measured by an O3 sonde is used as input in Tracy calculations. The O3 sonde is launched on the same balloon.