The Atmospheric Scanning Electron Microscope with open sample space observes dynamic phenomena in liquid or gas

Although conventional electron microscopy (EM) requires samples to be in vacuum, most chemical and physical reactions occur in liquid or gas. The Atmospheric Scanning Electron Microscope (ASEM) can observe dynamic phenomena in liquid or gas under atmospheric pressure in real time. An electron-permeable window made of pressure-resistant 100 nm-thick silicon nitride (SiN) film, set into the bottom of the open ASEM sample dish, allows an electron beam to be projected from underneath the sample. A detector positioned below captures backscattered electrons. Using the ASEM, we observed the radiation-induced self-organization process of particles, as well as phenomena accompanying volume change, including evaporation-induced crystallization. Using the electrochemical ASEM dish, we observed tree-like electrochemical depositions on the cathode. In silver nitrate solution, we observed silver depositions near the cathode forming incidental internal voids. The heated ASEM dish allowed observation of patterns of contrast in melting and solidifying solder. Finally, to demonstrate its applicability for monitoring and control of industrial processes, silver paste and solder paste were examined at high throughput. High resolution, imaging speed, flexibility, adaptability, and ease of use facilitate the observation of previously difficult-to-image phenomena, and make the ASEM applicable to various fields.     

Practical limitations of superresolution imaging due to conventional sample preparation revealed by a direct comparison of CLSM,SIM and dSTORM

We evaluate the suitability of conventional sample preparation and labelling methods for two superresolution techniques, structured illumination microscopy and direct stochastic optical reconstruction microscopy, by a comparison to established confocal laser scanning microscopy. We show that SIM is compatible with standard fixation procedures and immunofluorescence labelling protocols and improves resolution by a factor of two compared to confocal laser scanning microscopy. With direct stochastic optical reconstruction microscopy, fluorophores can theoretically be localized with much higher precision. However, in practice, with indirect immunofluorescence labelling density can be insufficient due to the bulky probes to reveal biological structures with high resolution. Fine structures like single actin fibres are in fact resolved with direct stochastic optical reconstruction microscopy when using small affinity probes, but require proper adjustment of the fixation protocol. Finally, by a direct comparison of immunofluorescent and genetic labelling with fluorescent proteins, we show that target morphology in direct stochastic optical reconstruction microscopy data sets can differ significantly depending on the labelling method and the molecular environment of the target.     

Molecular Transport of Aromatic Solvents through Oil Palm Micro Fiber Filled Natural Rubber Composites: Role of Fiber Content and Interface Adhesion on Transport

Cellulose micro fiber reinforced natural rubber composites were prepared and the diffusion and transport of aromatic solvents through these composites were studied in the temperature range 30–70°C. The diffusion parameters were investigated with special reference to the effect of fiber loading, penetrant size, temperature and interphase adhesion. The effect of chemical treatments on solvent uptake was also analyzed. The transport coefficients such as diffusion, permeation and sorption coefficients were determined to evaluate the influence of interphase adhesion on transport properties. The van't Hoff relationship was used to determine the thermodynamic parameters. The first order kinetic rate constant was evaluated. Finally, experimental results of the sorption properties of the composites were compared with theoretical predictions.     

Effect of Texture and Surface Chemistry of Palm Nut Hull Activated Carbon on the Adsorption of Pigments and Free Fatty Acids from Vegetable Oils

Activated carbons were produced from palm nut hull,which is a waste material of palm oil extraction industries.Activated carbons having various pore size distri...     

Replacing of glass fibres with seed oil palm fibres for tribopolymeric composites

Abstract

In the current study, the possibility of replacing woven glass fibres (WGFs) with seed oil palm fibres (SOPFs) as reinforcements for tribopolymeric composites is investigated. Mainly, two different polyester composites based on woven glass reinforced polyester (WGRP) and seed oil palm reinforced polyester (SOPRP) are developed. Different volume fractions (25, 35, and 45 vol.-%) of SOPFs were considered. The experiments were performed using a block on disc (BOD) machine and the tests were conducted under dry contact condition against smooth stainless steel counterface at 2˙8 m s^–1 sliding velocity, 20 N applied load for different sliding distances (up to 5 km). The wear mechanism was categorised using a Scanning Electron Microscope (SEM). The results revealed that the steady state was reached after 4 km sliding distance for both WGRP and SOPRP composites. Seed oil palm reinforced polyester composites showed very high friction coefficient compared to WGRP. 35 vol.-% SOPRP composite exhibited a promising wear result, i.e. SOPFs are possible to replace WGFs in polymeric composites reinforcements whereas the wear resistance of the synthetic and natural composite were almost the same. The wear mechanisms for SOPRP composites were predominated by microcracks, deformation and pulledout of fibres while in the WGRP composite, abrasive nature was observed.     

Live-cell super-resolution imaging goes multicolor

New resolutions: The combined use of photoactivatable fluorescent proteins and synthetic fluorophores considerably expands our options for multicolor super-resolution fluorescence imaging and enables for the first time the simultaneous imaging of more than two proteins with subdiffraction optical resolution in living cells.     

Unsupervised multi class segmentation of 3D images with intensity inhomogeneities

Intensity inhomogeneities in images cause problems in gray-value based image segmentation since the varying intensity often dominates over gray-value differences of the image structures. In this paper we propose a novel biconvex variational model that includes the intensity inhomogeneities to tackle this task. We combine a total variation approach for multi class segmentation with a multiplicative model to handle the inhomogeneities. In our model we assume that the image intensity is the product of a smoothly varying part and a component which resembles important image structures such as edges. Therefore, we penalize in addition to the total variation of the label assignment matrix a quadratic difference term to cope with the smoothly varying factor. A critical point of the resulting biconvex functional is computed by a modified proximal alternating linearized minimization method (PALM). We show that the assumptions for the convergence of the algorithm are fulfilled. Various numerical examples demonstrate the very good performance of our method. Particular attention is paid to the segmentation of 3D FIB tomographical images serving as a motivation for our work.     

基于PALM OS5的USB主机端协议栈的实现

针对目前PALMOS5操作系统还不能支持USB-HOST功能的问题,提出一种基于PALMOS5的USB主机端协议栈的实现方案。该文首先讨论在PDA上开发USB-HOST功能的必要性,并提出解决方案的总体架构。接着针对该总体构架的每一个部分具体分析其实现,并分析方案的可扩展能力,最后通过实现对USB存储设备的支持来验证方案的可行性。     

Reduction of coherent artefacts in super‐resolution fluorescence localisation microscopy

Super‐resolution localisation microscopy techniques depend on uniform illumination across the field of view, otherwise the resolution is degraded, resulting in imaging artefacts such as fringes. Lasers are currently the light source of choice for switching fluorophores in PALM/STORM methods due to their high power and narrow bandwidth. However, the high coherence of these sources often creates interference phenomena in the microscopes, with associated fringes/speckle artefacts in the images. We quantitatively demonstrate the use of a polymer membrane speckle scrambler to reduce the effect of the coherence phenomena. The effects of speckle in the illumination plane, at the camera and after software localisation of the fluorophores, were characterised. Speckle phenomena degrade the resolution of the microscope at large length scales in reconstructed images, effects that were suppressed by the speckle scrambler, but the small length scale resolution is unchanged at ～30 nm.     

Hundred‐Thousand light holes push nanoscopy to go parallel

With the application of the elements of all major super‐resolution techniques including stimulated emission depletion, structure illumination microscopy, and photo‐activated localization microscopy, the incoherent crossed standing‐wave microscopy achieves parallel super‐resolution imaging. Microsc. Res. Tech., 78:8–10, 2015. © 2014 Wiley Periodicals, Inc.