bluuebunny/crossref_metadata_2025_split huggingface dataset:
In situ
SEM
dynamic investigation of charging kinetics in insulating materials
Authors: Sao Joao Sergio , Mekni Omar , Goeuriot Dominique , Damamme Gilles 
Published: December 2016

Dielectric breakdown constitute an important limitation in the use of insulating materials since it causes its damage. This catastrophic phenomenon (Figure 1) is obviously an important failure in the levels of equipment requiring some insulation safety or ensuring their proper functioning. This causes some technological problems associated with the manufacture and use of insulating materials in several industrial sectors like in microelectronics, high voltage electric energy transport and spacecraft. The choice of insulating material for those applications is related to the corresponding breakdown voltage value which limits their use. To improve the resistance to dielectric breakdown, it is imperative to understand and control the cause of this damage process reducing the reliability of some instrumentation. It is well known that breakdown is correlated with the presence of space charge within the insulators. Indeed, breakdown is related to a fast relaxation (detrapping) of trapped charge. Commonly, this space charge can be determined by the SEMME method (Scanning Electron Microscope Mirror Effect) which quantifies the final trapped charge amount. The purpose of this work is to develop a technique using a specific arrangement in the SEM chamber (Figure 2) in order to characterize the trapped charge dynamic by ICM (Induced Current Method). This technique allows enhancing the understanding of trapping phenomenon, spreading and stability of trapped charges
The experiments were carried out in a FESEM (Field Emission Scanning Electron Microscope) Carl Zeiss SUPRA 55 VP using a specific configuration in the SEM sample holder (Figure 3). It permits to measure separately and simultaneously the influence current and the conduction current and tracing back to the trapped charge temporal evolution during (charging) and after (charge decay) electrons irradiation (Figure 4). Thereafter, the used technique of two injections separated by a pause time was a powerful method for monitoring and understanding the dynamics of the trapped and released charges in insulating materials. These results open the way for the establishment of a conventional characterization procedure, which will be useful in different contexts of use of insulating materials. The studied materials are α‐alumina and Yttria Stabilized Zirconia (YSZ) polycrystalline ceramics. Since the dielectric and electrical properties of an insulating material are highly dependent on its microstructure, the grain size effect and MgO doping effect are then studied and discussed. Via the developed technique, the microstructure ‐ dielectric rigidity correlations could be well justified.
Quantitative
3D
analysis of huge nanoparticles assemblies
Authors: Zanaga Daniele , Bleichrodt Folkert , Altantzis Thomas , Winckelmansa Naomi , Palenstijn Willem Jan , Sijbers Jan , de Nijs Bart , van Huis Marijn A. , Liz‐Marzán Luis M. , van Blaaderen Alfons , Batenburg K. Joost , Van Tendeloo Gustaaf , Bals Sara 
Published: December 2016

Nanoparticle assemblies attract increasing interest because of the possibility of tuning their properties by adjusting the overall size and shape, the stacking of the individual nanoparticles, and the distances between them.[1]
Transmission electron microscopy is an important technique to characterize materials at the nanometer scale and below. However, it conventionally only allows for the acquisition of two‐dimensional (2D) projections of three‐dimensional (3D) objects, which is not sufficient for a quantitative characterization of complex 3D nanostructures. Electron tomography has therefore been developed to overcome this strict limitation, becoming a versatile and powerful tool, increasingly used in the field of materials science.[2]
For the characterization of nano‐assemblies, electron tomography is nowadays a standard technique, yielding a 3D description of the morphology and inner structure.[3] Despite the valuable information that can be obtained, as the synthetized systems become more complex, an accurate characterization of the structure becomes more demanding. For example, 3D reconstructions based on classical algorithms, suffer from a number of restrictions that hamper an accurate characterization of closed‐packed nanoparticles assemblies.
Here, we present a novel approach that enables us to determine the coordinates of each nanoparticle in an assembly, even when the assembly consists of up to 10,000 (spherical) particles.[4, 5] This technique will have a major impact as it enables a straightforward quantification of inter‐particle distances and 3D symmetry of the stacking. Furthermore, the outcome of these measurements can be used as an input for modelling studies that predict the final 3D structure as a function of the parameters used during the synthesis.
Effect of trace elements on the material properties of an aluminium casting alloy
Authors: Schroettner Hartmuth , Pabel Thomas , Petkov Tose , Mertschnigg Sabrina , Rossmann‐Perner Anita 
Published: December 2016

The aim of the project is to determine the fundamentally effects of impurities and individual micro‐alloying elements (eg. as vanadium V, titanium Ti, calcium Ca, zirconium Zr, potassium K, phosphorus P and others) or combinations of these trace elements in aluminum alloys and their impact on the quality of aluminum castings.
As a result, limit values and tolerances for individual impurities (trace elements) should be defined and determined. Further on practical study methods should be developed that support on the one hand a reliable series production of high‐quality alloys and castings and on the other hand the procurement of aluminum alloys by the foundries.
The casting trials in industry‐related standards were performed on the base of a high purity alloy AlSi7Mg0,3 with systematic addition (30ppm, 300ppm, 3000ppm) of micro‐alloying elements, controlled by chemical analysis with an emission spectrometer.
Technological properties as flowability, hot crack susceptibility and shrinkage cavity formation were evaluated. Static and dynamic material testing, like tensile tests, hardness measurements and Woehler curves was implemented. The thermo‐physical properties as specific heat capacity, thermal expansion, temperature conductivity, density and heat conductivity were measured.
Phase calculations by ThermoCalc‐Software, to simulate the formation of intermetallic phases and their impact on the microstructure are compared to classical metallography and additional SEM/TEM‐investigations.
SEM/EDXS/EBSD‐measurements for the micro‐characterization of the structure and the composition of the intermetallic phases are made on cross sections (figures 1‐4).
Out from regions/phases of interest TEM‐lamellas are prepared with the FIB‐technique and transferred to TEM for using EDXS/EELS/EFTEM and diffraction methods for the nano‐characterization of these phases.
Transmission imaging of biological tissue with the Delft multi‐beam
SEM
Authors: Zuidema Wilco , Ren Yan , Hoogenboom Jacob , Hagen Cees , Kruit Pieter 
Published: December 2016

A major bottleneck for large‐scale and volume EM is the imaging speed. The total acquisition time needed for a single sample can easily take days, or even weeks using standard single‐beam SEM's. Multi‐beam microscopes have been developed to increase imaging speed[1,2], but it remains a challenge to achieve electron detection similar to a regular SEM in terms of signal type, contrast and resolution.
We have developed a SEM employing 196 electron beams using a standard column of a FEI Nova NanoSEM 200. The 196 electron beams are generated from a single high‐brightness Schottky electron source, making use of a square aperture lens array grid of 14 by 14 holes. Modified source optics allows focusing of all beams in the sample plane, with the same probe current and probe size as in a single‐beam SEM. Both secondary and transmission electron signals can be detected in the system, of which an overview is shown in figure 1. For the detection of the transmitted electrons, the sample of interest is placed on a scintillating screen and the light generated by each beam is collected through an optical objective lens. This light is focused on a CMOS camera placed outside the SEM chamber and the image is produced through online processing of the intensity of each beam. An example of rat pancreas tissue imaged by this method is shown in figure 2. The secondary electrons are focused on a scintillating screen in the variable aperture plane, making use of a retarding lens and the electron optics used for the focusing of the primary beams. This signal is again focused on a CMOS camera and the same process for imaging is performed as for the transmitted electrons.
We present proof‐of‐principle results showing that sub‐10nm resolution can be obtained for transmission imaging of stained rat pancreas tissue. We will discuss our efforts towards improving the detection methods and the data processing speed. Furthermore, work will be shown on quantifying and comparing the signals obtained from secondary, transmitted and backscattered electrons on stained tissue sections, as imaged by a conventional SEM.
Microscopy Image Browser: an open‐source platform for segmentation and analysis of multidimensional datasets
Authors: Belevich Ilya , Joensuu Merja , Kumar Darshan , Vihinen Helena , Jokitalo Eija 
Published: December 2016

Understanding the structure – function relationship of cells and cell organelles in their natural context requires multidimensional imaging. Recent technical advances especially in multimodal 3D‐5D imaging techniques have enabled a new insight into the morphology of tissues, cells and organelles. As the performance and access to such techniques are improving, the amounts of collected data are growing exponentially posing a question about effective processing, visualization, and analysis of these large datasets. Quite often the detailed analysis of multidimensional data is impossible without segmentation of objects of interest out of the volume (creating of a model). Usually the segmentation is the most time consuming and challenging part of the image analysis routine. For example, it may take up to a month to properly segment a single electron tomogram. The slowness of the process is caused by two main factors: limited number of good software tools (even commercial ones) and segmentation algorithms that can be applied to facilitate the modeling. As a result, the real potential of the collected data is not completely realized.
Here, we present a free user‐friendly software package (Microscopy Image Browser, MIB) for effective segmentation and image processing of multidimensional datasets that improves and facilitates the full utilization of acquired data and enables quantitative analysis of morphological features. MIB is written in Matlab language which is familiar to many researchers and available for main common operating systems (Windows, Mac and Linux); alternatively MIB is also distributed as a standalone package for both Windows and Mac OS. The access to the code and the open‐source environment enables fine tuning and possibility of adding new plug‐ins to customize MIB for specific needs of any research project.
Even though the focus of the program is 3D segmentation of electron microscopy datasets, MIB is rather universal and can be used to perform segmentation, analysis and visualization of 2D‐4D datasets obtained by light microscopy.
We already utilized MIB in more than 10 scientific research projects, where it allowed us to facilitating the segmentation part of the image processing workflow significantly. Here we demonstrate its successful application by presenting results of segmentation and quantification of cells and different cellular organelles imaged using various electron and light microscopy techniques.
Cryo‐
TEM
observations and Xray mapping of polyoxometalate / polystyrene hybrid nanoparticles with surface reactivity
Authors: de La Haye Jennifer Lesage , Guigner Jean‐Michel , Hasenknopf Bernold , Lacôte Emmanuel , Rieger Jutta 
Published: December 2016

Polyoxometalates (POMs) are metal‐oxygen clusters which can store electrons without altering their structure, so they are suitable for application in catalysis and materials science. In this project, we wished to synthesize surface catalytically active polystyrene‐polyoxometalate (PS‐POM) composite latexes through radical emulsion polymerization of styrene in water in the presence of amphiphilic POMs.
We used TEM analyses to demonstrate that polystyrene nanoparticles were stabilized by the POMs cluster at their surface. First, cryo TEM was used in order to determine the nanoparticles' shape and size. Secondly the photo‐catalytic activity of the POMs was evaluated. Upon UV irradiation, POMs can be photo‐reduced, in presence of organic molecules (acting as sacrificial electrons donors). According to the literature, the POMs attached to the PS surface should be able to transfer their captured electrons to metal ions, such as silver ions, to generate metals nanoparticles. We tested this benchmark reaction in the presence of our hybrid latexes. By Cryo TEM, we observed that nanoparticles were formed as expected in short reaction times, and that they were only present at the surface of PS‐POM composite latexes. In addition, Xray mapping at room temperature confirmed the presumed structure of the hybrid particles: POM clusters were only located at the particle surface by the detection of W atoms present in the used POM.
Gas
TEM
holder for in‐situ biasing and heating experiments
Authors: Vicarelli Leonardo , Zandbergen Henny 
Published: December 2016

We present our custom designed Gas Transmission Electron Microscopy (TEM) holder for in‐situ electrical, gas and heating experiments. The holder is currently compatible with FEI machines, but it can be easily redesigned for other transmission electron microscopes. The holder has a sliding cassette at the sample position (Figure 1, left side), which can be manually opened and closed through a rotating knob, located at the opposite end of the TEM holder. Closing the cassette will ensure complete gas sealing around the sample, up to a pressure difference of 1 atm (respect to the microscope vacuum). One gas line is used for both inlet and outlet.
The beam is blocked when the cassette is closed, meaning that it is not possible to acquire live imaging during the gas flow. However, this configuration is very practical from the point of view of sample loading and unloading, as it only takes a few minutes to replace the sample, without any O‐rings or complicated sealing mechanisms. Moreover, the sample does not need to be exposed to air after the gas reaction, which gives a relevant advantage over ex‐situ measurements.
The TEM holder also has 10 electrical feedthroughs, which can be used for in‐situ electrical biasing experiments. Four of these electrical contacts can be used for in‐situ heating, in combination with our custom made MEMS heaters [1] (Figure 1, right side), capable of reaching 1000 K in vacuum and 700 K in 1 atm Argon environment.
As a first application of our gas TEM holder, we exposed freestanding multilayer graphene to 1 atm of Hydrogen and simultaneously heated the sample at 550 K for a few minutes. As we can see from Figure 2, this high‐pressure hydrogen annealing resulted in isotropic etching of graphene, with formation of round holes, approximately 80 nm in diameter. Further experiments will be performed to evaluate the etching rate and the isotropicity/anisotropicity as function of temperature, pressure and gas composition.
A morphological approach for texture detection, application to SEM stereo reconstruction
Authors: Drouyer Sébastien , Beucher Serge , Bilodeau Michel , Moreaud Maxime , Sorbier Loïc 
Published: December 2016

3D surface reconstruction from multiple SEM images has been widely addressed in the scientific literature. Different approaches exist, most of them use variants of Digital Image Correlation (DIC) [1][2].DIC methods perform well on textured areas of images but provide limited results on uniform or flat zones. Approaches using segmentation techniques, that match discernible regions of images, provide a solution to solve this problem on low‐textured regions [3]. However, these methods are more computationally expensive and are less accurate than DIC on textured areas. Our objective is therefore to combine these two methods. One preliminary step is to differentiate textured areas, where DIC can be used, from low‐textured areas, where segmentation techniques are needed. This step will be addressed in this paper, and we propose a new approach using morphological operators to do that.Our approach uses the watershed operator with morphological gradient and markers obtained with h‐minima [4]. On each region, average gradient value is computed. Automatic thresholding and post processing using opening by criteria [5] is then performed to differentiate textured areas from low‐textured ones.Comparison of our approach with more standard methods of texture detection such as local entropy of local variance calculations [6] will be presented.A major benefit of our approach is that transition between textured areas and low‐textured ones strongly follow real contours of flat zones, limiting interpolation problems between DIC and methods using segmentation techniques.We will illustrate our texture detection algorithm by applying it on 3D surface reconstruction with SEM images of crystals of zeolites and catalyst with alumina supports.
Transmission Electron Microscopy of a Poorly Soluble Drug, Felodipine
Authors: S'ari Mark , Cattle James , Brown Andy , Rik Brydson , Hondow Nicole , Blade Helen , Cosgrove Steve , Hughes Les 
Published: December 2016

Many drugs that are currently in development exhibit poor dissolution properties due to low solubility. To increase the solubility of these drugs different technologies have been developed including solid dispersions, nano‐crystals and lipid formulations. Use of solid dispersions can increase solubility by dispersing a drug within an amorphous polymer matrix, inhibiting re‐crystallisation from the amorphous phase. This can be achieved by hot‐melt extrusion (HME), spray drying and co‐precipitation [1].
Transmission electron microscopy can be used to analyse different phases and morphologies within a solid dispersion which may not be found using conventional bulk techniques such as powder X‐ray diffraction, differential scanning calorimetry and Fourier transform infra‐red spectroscopy [2]. However, organic compounds can be easily damaged when exposed to the electron beam causing structural change, so low dose exposure is necessary to limit any damage that occurs [3].

The research here investigates a model system involving the drug felodipine and the copolymer copovidone. Solid dispersions of 15% and 50% felodipine were prepared by HME and then milled to form a powder. This powder was then dispersed in water, 3‐4 droplets were placed onto separate copper continuous carbon TEM grids and left to dry. These were then examined by TEM, operated at 200kV, equipped with a CCD camera. The electron flux was set between 0.007 ‐ 0.040 e
−
Å
2
s
−1
to limit any damage which may be caused by the high energy electrons [3].

The results show that within the 50% solid dispersions different morphologies and phases can be found, most areas show near amorphous diffraction patterns (Figure 1) but some show single crystal patterns (Figure 2). This suggests that the felodipine and copovidone are not always molecularly mixed and that small amounts of the felodipine had recrystallised after the initial HME process. Similarly, the 15% mixture had areas with varied morphologies and showed some signs of phase separation. The next step will be to quantify the identified phase fractions (amorphous, single crystal and nano‐crystalline) within these solid dispersions.
Quasi‐Nanofluidic liquid cell for in situ liquid Trasmission Electron Microscopy
Authors: Lagana Simone , Mikkelsen Esben Kirk , Sun Hongyu , Marie Rodolphe , Mølhave Kristian 
Published: December 2016

In this work we present a new microfabricated nanochannel device for in situ liquid TEM based on wafer bonding (Fig.1a). A schematic depiction of the chip cross section is presented in Fig.1b. The cell system was fabricated with a new direct bonding technique linking the adhesion properties of Silicon Rich Nitride (SiNx)/Stoichiometric Silicon Nitride (Si
3
N
4
) within atomic layer deposition (ALD) of Al
2
O
3
tuned for this application to provide low temperature bonding. The liquid vessel is designed with multiple nanochannels on a suspended membrane area, with tunable liquid layer thickness ~100 nm and silicon nitride windows ~ 50 nm. The channel design of the system improves the control of the top and bottom membrane bulging compared to commercial liquid cell devices and is hence expected to improve the area with high spatial resolution achievable in liquid TEM imaging. Our nanofluidic system together with a custom‐made flow holder will give further control of liquid conditions dynamically varying experimental conditions.

The liquid cell was first tested by optical fluorescence microscopy using a solution of 10 nm quantum dots (QD) and as depicted in Fig.2. Flow and diffusive motion of the QDs could be followed. In a Tecnai TEM at 200 kV, a solution of 30 mM HAuCl
4
was sealed in the channel with epoxy glue and upon TEM irradiation gold particles in average size between 5 and 15 nm were nucleated along the channels (Fig.3a). Sometimes rocking particle motion was observed, confirming their enclosure within the liquid layer (Fig.3b). In our design membranes are inner bending on each other and plastically deformed due to the extremely high (>12 bar) capillary force. Thus, a thin layer of water < 100 nm is trapped among the membranes. In contrast with other recent liquid vessels
[1]
, our nanofluidic system points toward higher resolution since liquid thickness [2], biomineralization synthesis
[3]
, liquid phase displacement and in liquid holography.