Effect of Weak Light on the Peroxidation of Membrane_Lipid of Cherry Leaves

The effect of weak light on the peroxidation of membrane_lipid of one_year_old cherries ( Prunus pseudocerasus L. 'Laiyang') was studied by whole_tree shading. The results showed that the net photosynthetic rate of cherry leaves under weak light was remarkably lower; the activity peroxidase (POD) increased when light intensity decreased; the activity of catalase (CAT) showed an opposite trend, and it was positively correlated with light intensity; the activity of superoxide dismutase (SOD) increased under 366 μmol·m -2 ·s -1 and 533.8 μmol·m -2 ·s -1 light intensity, but decreased under 228.8 μmol·m -2 ·s -1 and 83.9 μmol·m -2 ·s -1 light intensity. A remarkable increase of malondialdehyde (MDA), a product of membrane_lipid peroxidation, was also observed in cherry leaves when treated with weak light, indicating more serious peroxidation in the membrane.

Effects of Weak Light on the Ultrastructural Variations of Phloem Tissues in Source Leaves of Three-Year-Old Nectarine Trees(Prunus persica L.var. nectarina Ait.)

Leaves from three_year_old solar greenhouse nectarine trees ( Prunus persica L. var. nectarina Ait. “Zao Hong Yan”) were used as materials in this study. It was the first time that the ultrastructural characteristics of phloem tissues of source leaves were observed and compared in normal and weak light intensities using the transmission electron microscopy. Results showed that the average diameters of companion cells (CC) and sieve elements (SE) of all kinds of veins were bigger in normal than that in weak light intensity, indicating that light could influence the cell development and growth. Dense cytoplasm with abundant mitochondria, endoplasmic reticulums, multivesicular bodies, vesicles and plastids were observed in normal light intensity. On the contrary, CC with small vacuolar structures and few mitochondrias, endoplasmic reticulums were shown in weak light. Misalignment of grana thylakoid margins of nectarine leaves also was seen in weak light. The sieve pores of SEs were obstructed in weak light. Chloroplasts with numerous starch grains and few mitochondrias were noticed in the mesophyll cell (MES) surrounding the bundle sheath in weak light. The storage of starch grains appeared to result from an unbalance between photosynthate production and export of photosynthates. This observation provided a strong support to the point that most leaves export the most of assimilates in the light time. Plasmodesmal densities between SE/CC, CC/PP (phloem parenchyma cell), PP/PP and PP/BSC (bundle_sheath cell) decreased in weak light. Plasmodesmata were observed between CC/SE (NS) (nacreous_walled sieve element), PP/BSC in branch veins in normal light intensity, but not in weak light. Thus apoplasmic pathway may be the main mode of transport of assimilates in weak light, however symplasmic pathway may be the main mode of transport of assimilates in normal light intensity. These results demonstrated that the solar greenhouse nectarine trees could be adapted to the weak light via the ultrastructure variation of phloem tissues of the source leaves.

Effects of Weak Light on Starch Accumulation and Starch Synthesis Enzyme Activities in Rice at the Grain Filling Stage

Dynamic changes of starch, amylose, sucrose contents and the activities of starch synthesis enzymes under shading treatments alter flowering were studied using two rice varieties IR72 （indica） and Nipponbare （japonica） as materials. Under shading treatments, the starch, amylose and sucrose contents decreased, while ADP-glucose pyrophosphorylase （ADPGPPase） activity only changed a little, soluble starch synthase activity and granule bound starch synthase activity decreased, soluble starch branching enzyme （SSBE, Q-enzyme） activity and granule bound starch branching enzyme （GBSBE, Q-enzyme） activity increased, and starch debranching enzyme （DBE, R-enzyme） activity varied with varieties. Correlation analyses showed that the changes of starch content were positively and significantly correlated with the changes of sucrose content in the weak light. Both ADPGPPase activity and SSBE activity were positively and significantly correlated with starch accumulation rate. It was implied that the decline of starch synthase activities was related to the decrease of starch content and the increase of the activity of starch branching enzyme played an important role in the decrease of the ratio of amylose to the total starch under the weak light.

Accumulation and Gene Expression of Anthocyanin in Storage Roots of Purple-Freshed Sweet Potato [Ipomoea batatas (L.) Lam] Under Weak Light Conditions

Anthocyanidin in plants, an important pigment, is of great interest to researchers, consumers, and commercial entities due to its physiological functions. Anthocyanin content and mRNA levels of anthocynin biosynthesis genes were investigated in storage root of different purple-fleshed sweet potatoes (PFSP) genotypes to understand the regulation mechanism of anthocyanin under weak light conditions. Anthocyanin content, its amount of accumulation, and the expression of CHS, DFR, F3H, GT, and ANS genes in the PFSP storage root under weak light conditions were studied. The results demonstrated that the anthocyanin content of the treatments was decreased and was obviously lower than that of the control until 30 days after shading in Ayamurasaki, while it was lower than that of the control from the beginning of shading in Jishu 18. Their accumulation rates of both treatmeants were lower than its control before 10-20 d of shading in Jishu 18, while those of Ayamurasaki weren't in their treatments. This indicated that Jishul 8 is more sensitive to light as compared to Ayamuraska. Under the different weak light conditions, mRNA levels for ibCHS, ibF3H, ibDFR, and ibANS were obviously decreased, while the expression of ibGT was increased. These results indicated that anthocyanin content was regulated by light at the mRNA levels and the enzymatic level in sweet potato. Therefore, the development dynamic response to anthocyanin content varied in different genotypes of PFSP, and mRNA levels of anthocyanin biosynthesis were inhibited under the weak light condition.

Effect of Weak Light on the Photoassimilates Distribution and Transformation of Young Grape Plants

The effect of weak light on the photoassimilates distribution and transformation of young Jingyu grape plants ( Vitis vinefera L. cv. Jingyu) were studied by shading. Compared to the grape grown under natural light intensity environment, the net photosynthetic rate diurnal variation curve of experimental plants grown in weak light intensity environment was remarkably lower. Its leaf and stem biomass ratio increased when light intensity decreased, the root and new shoot biomass ratio showed an opposite trend. The 14 C-photoassimilates was mostly distributed to young leaves and stem, a little was distributed to root. The metabolism of 14C-photoassimilates distributed to the entire grape body were also changed under weak light intensity environment.

Self-powered broadband kesterite photodetector with ultrahigh specific detectivity for weak light applications

Kesterite Cu_(2)ZnSn(S,Se)_(4)(CZTSSe)is a promising candidate for photodetector(PD)applications thanks to its excellent optoelectronic properties.In this work,a green solution-processed spin coating and selenization-processed thermodynamic or kinetic growth of high-quality narrow bandgap kesterite CZTSSe thin film is developed.A self-powered CZTSSe/CdS thin-film PD is then successfully fabricated.Under optimization of light absorber and heterojunction interface,especially tailoring the defect and carrier kinetics,it can achieve broadband response from300 to 1300 nm,accompaniedwith a high responsivity of 1.37A/W,specific detectivity(D*)up to 4.0×10^(14)Jones under 5 nW/cm^(2),a linear dynamic range(LDR)of 126 dB,and a maximum Ilight/Idark ratio of 1.3×10^(8)within the LDR,and ultrafast response speed(rise/decay time of 16 ns/85 ns),representing the leading-level performance to date,which is superior to those of commercial andwell-researched photodiodes.Additionally,an imaging system with a 905nm laser is built for weak light response evaluation,and can respond to 718 pW weak light and infrared imaging at a wavelength as low as 5 nW/cm2.It has also been employed for photoplethysmography detection of pulsating signals at both the finger and wrist,presenting obvious arterial blood volume changes,demonstrating great application potential in broadband and weak light photodetection scenarios.

All-inorganic CsAgBiBr/Cu SCN-based photodetectors for weak light imaging

Weak light imaging has drawn more and more attention because of its promising potential for practical applications in security monitoring and space exploration. In this work, all-inorganic Cs2AgBiBr6 double perovskite-based self-powered photodetectors containing inorganic copper thiocyanate(CuSCN) as hole-transport layers(HTLs) are successfully fabricated and applied for weak light imaging,which is the first report on the weak light imaging application of all-inorganic lead-free perovskite photodetectors. CuSCN films with favorable optical property and hole extraction capability are prepared via a cost efficient and fast solvent removal method, demonstrating the potential for high-performance perovskite-based devices as transparent components. It is revealed that the band alignment of the device is effectively optimized with the presence of CuSCN HTLs,which can availably transport holes while block electrons at the Cs2AgBiBr6/CuSCN interface, resulting in remarkable improvement of photoresponse performance. The responsivity and detectivity are 0.34 A W^-1 and 1.03×10^13 Jones,respectively. In particular, the light current has a boost of almost 10 times. Furthermore, the photodetectors are integrated into a self-built light detection imaging system utilizing the focused laser scanning imaging mode. With illumination of as low as 5 nW cm^-2(405 nm), the image involving graphics and words with a size of 5 cm×5 cm can still be distinctly recognized. These results suggest the promising potential of all-inorganic perovskite-based devices for weak light detection and imaging applications.

Spatial weak-light ring soliton in self-assembled quantum dots

By using semiclassical theory combined with multiple-scale method, we analytically study the linear absorption and the nonlinear dynamical properties in a lifetime broadened Λ-type three-level self-assembled quantum dots. It is found that this system can exhibit the transparency, and the width of the transparency window becomes wider with the increase of control light field. Interestingly, a weak probe light beam can form spatial weak-light dark solitons. When it propagates along the axial direction, the soliton will transform into a steady spatial weak-light ring dark soltion. In addition, the stability of two-dimensional spatial optical solitons is testified numerically.

50份加工型辣椒DH系苗期耐低温弱光综合评价

以前期利用花药培养技术创制的50份加工型辣椒DH系为试验材料,以SPAD值、F_(v)/F_(m)、根系直径、茎叶干质量、根系干质量、整株干质量和根冠比7个指标的耐低温弱光指数为评价指标,采用模糊隶属函数和聚类分析法对其进行耐低温弱光综合评价。结果表明:50份DH系的耐低温弱光模糊隶属函数综合指数范围在0.20~0.76之间,聚类分析可将其分为两大类,根据耐低温弱光指数特点和模糊隶属函数综合指数可确定第Ⅱ类有7份DH系为耐低温弱光材料,即H201605-8、H201604-4-1、H201612-4-1、H201605-7、H201612-4、H201605-34和H201604-18。50份加工型辣椒DH系间耐低温弱光性差异较大,可作为相关机理研究的试验材料;筛选出的7份耐低温弱光DH系为培育适合设施栽培的优良辣椒新品种提供了材料基础,也为定向培育抗非生物逆境辣椒种质新材料提供了参考。

弱光下锑基太阳电池的光谱响应与性能优化

锑基薄膜太阳电池因其制备方法简单,原材料丰富,光电性能稳定等优点而得到了快速发展。其中锑基吸光层材料(硫化锑、硫硒化锑、硒化锑)具有高吸收系数特点,因而在室内或者水下等弱光条件下具有相当大的应用潜力。通过构造两种衰减光谱以研究新型锑基薄膜太阳电池在弱光下的光电响应。首先通过厚度调节硒化锑太阳电池的吸光能力,发现当吸光层厚度较薄时,电池的光电转换效率存在较大差值;而当吸光层厚度过厚时,电池性能又因载流子复合的增大而降低。在吸光层厚度处于合适的0.4~1.2μm之间时,硒化锑太阳电池在长波衰减光谱和短波衰减光谱下都能获得高于16%的转换效率。然后通过硒含量调节锑基太阳电池的光谱吸收范围,发现长波衰减光谱下,锑基太阳电池的器件性能显著高于标准光谱,并且在20%~40%硒含量下能够获得最佳的转换效率。而在短波衰减光谱下,锑基太阳电池的最佳性能出现在硒含量为60%的情况下。因而在弱光条件下,锑基太阳电池的最佳硒含量需要通过具体的光谱特性确定。最后研究了两种衰减光谱下,硫化锑/硒化锑双结叠层太阳电池的光谱响应特性。发现在短波衰减光谱下,叠层太阳电池效率会随着总厚度的增加而增加。而在长波衰减光谱下,叠层太阳电池的最佳性能能够一直保持在较高水平。当叠层电池总厚度为2μm,且硫化锑顶电池厚度在0.5~1.2μm之间时,器件在两种衰减光谱下都能够实现光谱能量在两个子电池中的合理分配,使得叠层电池效率能够保持在20%以上。通过该研究对锑基太阳电池器件结构的合理设计,能够保证单结和双结器件在不同弱光条件下的高性能输出,为高环境适应性的锑基薄膜太阳电池的研发提供技术支持。

LEGAN:一种新的暗弱光照图像增强算法

针对暗弱光照图像所存在的亮度、对比度、信噪比低,以及噪声污染大等问题,提出了一种新的暗弱光照图像增强算法LEGAN。该算法将图像输入至所提伽马曲线估计网络求得包含伽马参数的特征图,再经过LEB模块增强亮度,并通过级联LEB的方式迭代增强结果。采用基于PatchGAN的全局-局部判别器结构来提高图像分辨率和恢复图像细节。通过引入感知损失来限制真实标签和输出结果之间的差距,利用照明平滑度损失保持相邻像素之间的单调性关系,同时结合空间一致性损失来增强图像的空间相关性。实验结果表明,相比于现今大多数主流增强算法,该算法的细节还原度相对较高,且能有效避免增强后的图像出现局部亮度不佳等问题。

弱光及干旱条件下AMF对切花月季光合和AsA-GSH循环的影响

旨在探究弱光及干旱条件下丛枝菌根真菌(AMF)对切花月季光合、AsA-GSH循环以及渗透调节物质的影响。盆栽条件下设置100%全光照(L1)、50%全光照(L2)2个光照处理组,80%土壤持水量(W1)和40%土壤持水量(W2)2个水分处理组,接种AMF[变形球囊霉(Glomus versiforme)+异形根孢囊霉(Rhizophagus irregularis)]及不接种对照(CK)共8个处理。结果表明,AMF能够侵染切花月季根系,显著提高切花月季生长品质。弱光和/或干旱胁迫下,与不接种对照相比,接种AMF能有效地促进切花月季叶片的净光合速率(P_(n))、蒸腾速率(T_(r))、气孔导度(G_(s))和水分利用效率(WUE)增加,降低细胞间隙CO_(2)浓度(C_(i));在L2W2处理条件下,与不接种对照相比,接种AMF使切花月季叶片中的抗坏血酸过氧化物酶(APX)、谷胱甘肽还原酶(GR)、单脱氢抗坏血酸还原酶(MDAR)和脱氢抗坏血酸还原酶(DHAR)活性分别提高5.2%、15.4%、21.7%和35.9%;接种AMF的抗坏血酸(AsA)含量与对照处理无显著差异,还原型谷胱甘肽(GSH)含量提高8.1%,GSH/GSSG比值增加7.9%;接种AMF后切花月季丙二醛(MDA)含量显著降低,可溶性糖、可溶性蛋白和脯氨酸(Pro)含量明显增加。结论认为AMF通过维持AsA/DHA和GSH/GSSG的稳定,提高AsA-GSH循环中相关酶活性,增加切花月季叶片可溶性糖、可溶性蛋白和脯氨酸含量而降低MDA含量来适应水分和光照的变化,形成适应光照和水分条件变化的生理生态对策来改善切花月季生长品质。

基于YOLOv5水下目标检测算法研究与改进

在水下目标生物的检测过程中,由于水下环境恶劣,水中光线衰弱,以及大多水下生物以小目标的形态出现等问题,使得目前的水下目标检测带来了精度损失问题,为解决相应问题,给出了一种基于YOLOv5s改进的YOLOv5s-water算法来解决。首先通过STR(Swin-Transformer)旋转窗口来对YOLOv5s的主干层(Backbone)部分进行更改,提高模型的泛化能力,进而解决水下环境恶劣以及检测目标形态变化带来的问题。使用FReLU激活函数与CBAM注意力神经机制结合成的FCM注意力机制,将其嵌入到YOLOv5s的骨干网(Neck)部分,以用来突出目标特征并抑制次要信息,从而提高算法精度,加强小目标的特征提取。小目标检测方面,在YOLOv5结构上增加小目标检测头,以提高感受野,进而提高小目标的检测精度。仿真和实验结果表明:所提方法相较于YOLOv5s检测准确率P上升1.47%,精确度mAP@0.5上升2.76%,小目标检测效果明显,证明了方法的有效性。

基于深度学习的水下激光通信系统弱光信号检测方法研究

水下激光通信系统弱光信号受到频谱和多径干扰,检测的精度不高,为了提高水下激光通信的稳定性,提出基于深度学习的水下激光通信系统弱光信号检测方法。采用空间波束形成方法构建水下激光通信采集和多层频谱分解模型,实现信号的波束特征增强处理,结合时间反转技术估计弱光信号的射频标签分布信息和多径信息,采用多径衰落抑制实现对水下激光通信系统的弱光信号增强处理,利用深度学习算法进行弱光信号检测过程中的寻优控制,使得整个信号检测过程保证在恒虚警概率。仿真结果表明,该方法进行水下激光通信系统弱光信号检测对多径衰落的抑制能力较好,不同信噪比环境下误码率较低,当信噪比增大至90 dB时,其误码率仅为10-5,且其检测时间小于10 ms,优于对比方法,具有更大的应用价值。

用于超构表面衍射光帆光力测量的扭秤设计

基于超构表面技术的衍射光帆在矢量光场的作用下,其最大加速度、自稳定推进力和姿态可控性可以得到提高。在真空环境中,精确测量衍射光帆在矢量光场作用下产生的光力对建立完整的空间动力学模型至关重要。基于扭秤弱力测量技术,本文分别设计了面向形状规则与不规则的衍射光帆的光力测量扭秤。对于形状规则的光帆,可通过严格控制扭秤的尺寸及各部件相对位置误差等方法提高测量精度,该扭秤理论测量误差为0.55‰。形状不规则光帆样品的转动惯量及误差难以精确计算,通过在扭秤上增加可随时取放的标准球,标准球的转动惯量可以通过其几何尺寸及位置严格计算,测量扭秤在有无标准球的状态下的周期即可以给出其受到的光力大小。本研究提升了光力测量实验的效率和灵活性,为光帆推进、空间碎片轨道操控等应用提供数据支撑。

一种适用于监控系统中弱光条件的光伏逐日系统

太阳能是当前具有代表性的绿色能源之一,固定式光伏支架由于安装方向固定,光伏面板无法始终朝向太阳,而光伏逐日系统的监控系统对于跟踪其性能和确保高效运行至关重要。因此,该文提出一种基于监控系统中可适用于弱光条件下的光伏逐日系统,采用信捷XC3 PLC承担其主要程序控制任务,利用光敏传感器收集各个方向的光强差值,通过程序计算出最佳光照角度,进而驱动电机调整为最佳照射角度,将云量和天气预报数据集成到监测系统中,以预测阳光变化并相应地辅助逐日系统运行。大幅提高光电转化率。

基于四电平编码与弱光通信的极低功耗传光式电流互感器

针对传光式电流互感器高压侧现有的母线取能和激光供能方式存在供电死区、能量转换效率低、使用寿命不足等问题,提出一种基于四电平编码与弱光通信的极低功耗光电传输系统方案。首先,设计三态门电路将信号采集模块的采样时钟和数据信号叠加为一个四电平信号。然后,利用超高亮度且极低功耗的LED将四电平信号转换为光信号并通过光纤传输至低压侧。最后,在低压侧通过高灵敏度雪崩光电二极管探测器进行弱光检测后输入解码电路实现信号解码。将极低功耗光电传输系统应用于传光式电流互感器中进行实验验证,测量结果满足0.2级精度要求,系统高压侧的平均功耗可降低至3.91 mW,保证测量精度的同时大幅降低了功耗。由于高压侧的功耗极低,故可采用大容量电池或小功率光伏系统等可靠供能方案,从而解决了高压侧的供能问题,提高了系统的稳定性和可靠性。

花后弱光对软质小麦籽粒产量与淀粉品质的影响

为探明花后弱光胁迫对软质小麦籽粒产量、淀粉粒度分布及黏度参数的影响,以软质小麦品种荃麦725和扬麦15为材料,在小麦开花后设置3个弱光处理即S1(遮光10%)、S2(遮光20%)、S3(遮光30%)处理,以自然光照条件为对照,分析花后不同程度弱光条件下软质小麦籽粒产量、淀粉粒度分布与黏度参数的差异。结果表明,与对照相比,花后弱光降低了小麦粒重、穗粒数和产量,提高了籽粒蛋白质含量,但使籽粒淀粉含量、籽粒蛋白质和淀粉积累量显著减少。花后弱光降低了软质小麦B型淀粉粒(粒径≤10μm)体积、表面积百分比,增加了A型淀粉粒(粒径>10μm)体积、表面积百分比,对A、B型淀粉粒数目百分比无显著影响。在B型淀粉粒中,弱光对粒径0.1~2.8μm的淀粉粒体积百分比的影响较粒径2.8~10μm的淀粉粒大。在A型淀粉粒中,弱光对粒径>22μm的淀粉粒体积百分比的影响大于粒径10~22μm的淀粉粒。弱光导致小麦籽粒淀粉峰值黏度、低谷黏度、最终黏度、稀懈值、回升值等参数显著下降。花后弱光虽然可增加软质小麦籽粒蛋白质含量,但显著降低籽粒淀粉含量以及蛋白质和淀粉积累量,不利于粒重与产量形成;弱光对B型淀粉粒的影响大于A型淀粉粒,会降低B型淀粉粒体积和表面积占比,但可增加A型淀粉粒体积和表面积占比,降低淀粉峰值黏度等参数。

弱光照图像的模糊细节自调节增强测试与仿真

由于自然光具有较强的随机性,低光照条件下相机采集的图像较为模糊,难以获取细节信息。为此,提出弱光照图像模糊细节自调节增强方法。在非局部均衡滤波算法中引入相似度阈值函数,去除弱光照模糊图像噪声,采用分数阶全变差模型和非局部全变差模型,建立弱光照模糊图像去模糊模型,对模糊图像去模糊处理,将预处理后弱光照图像输入多尺度融合卷积神经网络模型,通过全局路径和局部路径提取并融合图像特征,实现弱光照图像模糊细节自调节增强。实验结果表明,所提方法在合成图像增强中均方误差更小、结构相似度和峰值信噪比更高,在真实图像增强中自然图像质量评价度量和对比度增益更高、熵值更接近于8,图像处理时间更短,仅为0.745ms。

微生物活化钾长石对玉米抗弱光低温逆境的研究初报

解钾菌活化钾长石的肥效不仅与微生物的活化效果有关,还与微生物的抗光温逆境功能有关。在3个恒温光照培养箱分别设置了弱光、全光和弱光低温条件下的玉米苗栽培试验,比较化肥(氯化钾)、微生物活化钾长石和化学活化钾长石在不同光温条件下的肥效。结果表明:微生物活化钾长石在全光和弱光条件下的肥效均优于化肥的,揭示了微生物不仅能活化矿质营养,还具有抗光温逆境的功能;在弱光条件下,微生物活化钾长石处理的玉米鲜质量和干质量较优,表明微生物分泌物提供的有机碳营养可补充弱光下光合产物的亏缺,其优势得以凸显;在全光条件下,化学活化钾长石处理的玉米鲜质量和干质量较高,表明全光条件下的光合产物较弱光条件下的有大幅增加,使碳亏缺大为缓解,其肥效得以更好地发挥;就抗光温逆境而言,化肥处理仍然不具有微生物活化的优势。