Functional organisation of the endomembrane network in the digestive gland of the Venus flytrap: revisiting an old story with a new microscopy toolbox

Up-to-date imaging approaches were used to address the spatiotemporal organisation of the endomembrane system in secretory cells of Dionaea muscipula. Different ‘slice and view’ methodologies were performed on resin-embedded samples to finally achieve a 3D reconstruction of the cell architecture, using ultrastructural tomography, array tomography, serial block face-scanning electron microscopy (SBF-SEM), correlation, and volume rendering at the light microscopy level. Observations of cryo-fixed samples by high-pressure freezing revealed changes of the endomembrane system that occur after trap activation and prey digestion. They provide evidence for an original strategy that adapts the secretory machinery to a specific and unique case of stimulated exocytosis in plant cells. A first secretion peak is part of a rapid response to deliver digestive fluids to the cell surface, which delivers the needed stock of digestive materials ‘on site’. The second peak of activity could then be associated with the reconstruction of the Golgi apparatus (GA), endoplasmic reticulum (ER) and vacuolar machinery, in order to prepare for a subsequent round of prey capture. Tubular continuum between ER and Golgi stacks observed on ZIO-impregnated tissues may correspond to an efficient transfer mechanism for lipids and/or proteins, especially for use in rapidly resetting the molecular GA machinery. The occurrence of one vacuolar continuum may permit continuous adjustment of cell homeostasy. The subcellular features of the secretory cells of Dionaea muscipula outline key innovations in the organisation of plant cell compartmentalisation that are used to cope with specific cell needs such as the full use of the GA as a protein factory, and the ability to create protein reservoirs in the periplasmic space. Shape-derived forces of the pleiomorphic vacuole may act as signals to accompany the sorting and entering flows of the cell.     

Common Mode Voltage Reduction Using 3D-SVPWM for 3-level CI-NPC Inverter with Hybrid Energy System

This paper elucidates Common Mode Voltage (CMV) reduction in transformerless 3-phase 3-level Coupled Inductor Neutral Point (CI-NPC) Clamped Inverter with Hybrid Energy System. The three dimensional Space Vector Pulse Width Modulation (3D-SVPWM) with Nearest State Vector (NSV) is implemented to reduce the CMV by proper selection of medium, large and small vectors in 3D cubic space region. This NSV scheme in addition to CMV reduction, reduces the capacitor voltage balancing issues and minimizes switching losses. The proposed control provides full utilization of dc link voltage with reduced harmonics. This 3-level CI-NPC inverter is energized by hybrid energy source which includes photovoltaic system and wind energy system. The results obtained for the proposed scheme through simulation and experimental setup is compared with the conventional 2D-SVPWM and 3D-SVPWM scheme. From the compared results it is evident that the proposed scheme reduces CMV to a larger extent than 2D and 3D-SVPWM control. The simulation and experimental results are verified using matlab-simulink and FPGA-Spartan-6 controller respectively.     

In situ electrodeposition of nickel cobalt selenides on FTO as an efficient counter electrode for dye-sensitized solar cells

Construction of transition metal selenides with high electrocatalytic performance is of significant importance, but it is still a challenge to develop the corresponding counter electrodes (CEs) by an electrodeposition technique. In the present work, nickel cobalt selenide (Ni_xCo_ySe) films are prepared in situ on fluorine-doped tin oxide (FTO) glasses through a potential reversal electrodeposition technique. The morphology and electronic structure of Ni_xCo_ySe films can be tuned by controlling the Ni/Co molar ratio in electroplating solution. Specially, Ni_xCo_ySe-6 film (the Ni/Co molar ratio of 1:1) with the optimized interaction between the Ni and Co elements displays numerous particles composed of sheets attached with nanocrystals, resulting in the more electrocatalytic active sites. Benefiting from the unique morphology and optimized synergistic effect, Ni_xCo_ySe-6 CE exhibits superior electrocatalytic activity for the triiodide reduction. Then, the dye-sensitized solar cell (DSC) fabricated by Ni_xCo_ySe-6 CE has demonstrated a power conversion efficiency (PCE) over 7.40%, which is higher than that of platinum (Pt)-based device (6.32%). Furthermore, Ni_xCo_ySe-6 array CE is also prepared by using polystyrene array as template. The PCE of the DSC with Ni_xCo_ySe-6 array CE reaches its maximum value of 7.64% and 20.9% larger than that of Pt-based device.     

川西廊坊式街市探析

文章通过对保存完整的川西小镇黄龙溪这一街道，民居，寺庙有机整体的分析，阐述了颇具地方特色的廓坊街市的空间形态特征。根据黄龙溪浓郁的乡土文化特点，提出如何继承与开发这一质朴的建筑文化遗产。     

纳秒脉冲触发的阵列微空心阴极放电特性

阵列微空心阴极(MHC)是一种在同一个阴极结构上加工多个微孔形成微孔阵列,实现大面积高电子密度的放电微等离子体结构。相比直流触发模式,纳秒短脉冲触发阵列微空心阴极,可以显著地减少直流触发时的电流热负荷效应,提高放电电流和放电能量。本文利用自行研制的纳秒脉冲电源,实现对阵列微空心阴极在氩气下进行脉冲放电,研究其脉冲条件下的放电特性;其次,研究其在纳秒脉冲下多孔阵列的同步放电问题,并通过加入预触发结构,有效改善其同步特性;最后,利用光纤式发射光谱仪进行氩气下氩发射光谱测量,并对纳秒放电等离子体进行光谱诊断。     

机动式车载自适应光学波前处理器的设计

为满足机动式车载自适应光学系统的需求,设计了专用的波前处理器。该波前处理器采用波前处理主板、波前处理子板和DA转化板相结合的硬件架构,由光纤作为通信载体。在满足功能需求的同时提高了系统的可靠性;波前处理器是自适应光学系统闭环控制的运算中心,其运算延时直接影响系统的控制带宽。本文提出一种基于FPGA的多线流水自适应光学实时波前处理方法,实现了波前斜率计算、复原运算和控制运算。结果表明:对于两级精密跟踪,97个子孔径以及97单元变形镜的自适应光学系统,系统处理延时为506.25μs,满足系统1 500Hz的实时波前处理需求。     

球面上微透镜阵列超精密慢伺服加工精度影响因素的研究

超精密慢伺服车削可加工出高精度的连续和非连续自由曲面,但是在微透镜阵列的加工过程中,不同位置的透镜加工精度也不同,个别子透镜的质量降低可能引起整个功能部件的失效。为了研究曲面上微透镜阵列超精密慢伺服加工精度的影响因素,本文采用实验的方法分析基面几何形状和子透镜位置对球面上微透镜阵列慢伺服车削加工精度的影响,通过在三种不同球径的基面上加工微透镜阵列,并使用Bruker GT-X白光干涉仪测量所加工的基面和微透镜阵列,分析了不同基面上不同位置的子镜表面粗糙度和形状精度的变化趋势。实验结果表明,同一基面上不同位置的子透镜,慢伺服车削加工表面微观形貌不同,表面粗糙度和形状精度也不同;基面的几何形状也会影响子镜的加工精度,当基面球径从50 mm增大至150 mm时,外圈子镜的表面粗糙度从75.78 nm(Ra)变小为69.08 nm(Ra)。在超精密慢伺服加工微透镜阵列过程中,必须考虑基面几何形状和子透镜位置两个因素对加工精度的影响,这将有助于提高微透镜阵列加工精度的一致性并保证微透镜阵列功能的有效性。     

BGA焊球视觉检测算法及系统设计

为了实现对BGA焊球的自动检测,建立了自动视觉检测系统。对系统所采用的焊球特征进行提取及缺陷识别,基于高斯混合模型的分类器对检测算法进行研究。根据焊球的形状和尺寸特征设计了焊球缺陷识别和分类算法,并以锡多、锡少和毛刺缺陷为例,分析典型缺陷的识别算法。以焊球形状的圆度和特征区域的面积等特征参数为评价标准,构建二维特征空间。在二维特征空间线性组合的基础上,构建基于高斯混合模型的分类器。构建了训练样本集,并对该分类器进行训练,根据训练结果并结合应用实际修正了模型,并采用测试集对该分类器进行测试验证。实验结果表明,焊球缺陷检测算法的准确度为97.06%,漏判率为0%,检测可靠度为100%。该视觉检测系统满足了工程运用中对识别准确度、稳定性、可靠性等方面的要求。     

An array waveguide probe for detection,location and sizing of surface cracks in metals

The paper describes the development of a novel microwave probe for detection, location and sizing of surface cracks in metals. The probe utilizes the inherent mutual coupling in an array structure to determine crack alignment, placement and dimensions. The main feature of the probe is its ability to electronically scan the region of concern, thus avoiding the large inspection time and unwanted noise experienced in the conventional mechanical scanning. Theoretical and experimental results are presented for a prototype two-cell array probe when scanning a metallic specimen containing a long surface crack. It is shown that the probe is capable of determining the orientation, location and dimensions of surface cracks of a few millimeters depth.     

A DNA macro-array to simultaneously identify 32 meat species in food samples

Considering the recent cases of meat adulteration and fraud, efficient and accurate analytical methods are needed for the specific identification of meat species as a key importance to maintain consumers' trust and to comply with various local labelling legislations. As a reference approach, the application of PCR to meat speciation is always limited to few species, whereas there is a strong need to broaden the number of identified meat species. PCR was here associated with a commercial DNA macro-array spotted with meat-specific capture probes, allowing the simultaneous identification of 32 meat species on 8 samples per chip support. Tested on pure meat samples, spiked samples, proficiency test samples, and processed samples, the method showed high specificity on the targeted species and allowed a sensitivity down to 1% (w/w). Easy-to-use, fast and cost-efficient, this multi-screening approach is fit-for-purpose as a tool to detect meat substitution or adulteration for meat testing laboratories.