bluuebunny/crossref_metadata_2025_split huggingface dataset:
In situ High Temperature
ESEM
study of carbon nanotubes reactivity under oxidative conditions
Authors: Mehedi Hassan‐Al , Podor Renaud , Ravaux Johann , Michel Thierry , Tahir Said , Yazda Khadija , Odorico Michael , Jourdain Vincent 
Published: December 2016

Due to their extraordinary mechanical, electrical, optical, thermal … properties, single wall carbon nanotubes (SWCNTs) have attracted tremendous studies in the last 20 years. However, most of these properties are closely related with the defects present in the carbon layer and with the chirality of the SWNCTs. Two specific studies have been performed in order to better understand the high temperature behavior of SWCNTs, using the high temperature device attached with the environmental scanning electron microscope (HT‐ESEM mode).
SWCNTs imaging (Fig. 1): Isolated SWCNTs cannot be observed directly in the HT‐ESEM due to the relatively poor resolution of this technique. The SWCNTs are deposited on an insulating substrate and low voltage (1‐3kV) charge contrast imaging is used to directly observe the CNTs. While the ESEM is not supposed to operate in such high voltage conditions at high temperature, aligned CNTs images have been recorded under various gas compositions and pressures using the gaseous secondary electron detector. These images have demonstrated the possibility to observe the SWCNTs at high temperature in the ESEM and have opened the path for further in situ experiments in the microscope chamber.
We studied the chemical reactivity of individual single‐walled carbon nanotubes on oxide substrates toward oxygen etching using HT‐ESEM (Fig. 2) coupled with AFM observations. Our in situ observations show that the reactivity of carbon nanotubes on substrates is different from that of free‐standing ones. In particular, semiconducting nanotubes appear as or slightly more reactive than metallic ones, showing that the nanotube type has a secondary influence compared with that of the substrate. In addition, carbon nanotubes are not progressively etched from their ends as frequently assumed but disappear segment by segment. Atomic force microscopy before and after oxidation reveals that nanotube oxidation proceeds first by a local cutting leading to two separate nanotube segments, which is then followed by a rapid etching of the segment that has been electrically disconnected from others. In addition, our study shows that exposure to electron and laser beams can strongly increase the chemical reactivity of single‐walled carbon nanotubes on substrates. These results are rationalized by considering i) the effect of substrate‐trapped charges on the nanotube density of states close to the Fermi level, and ii) the effect of electron and laser beams on the density of these surface charges.
A new method for quantitative
XEDS
tomography of complex hetero‐nanostructures
Authors: Zanaga Daniele , Altantzis Thomas , Polavarapu Lakshminarayana , Liz‐Marzán Luis M. , Freitag Bert , Bals Sara 
Published: December 2016

Over the last decades, electron tomography based on HAADF‐STEM has evolved into a standard technique to investigate the morphology and inner structure of nanomaterials. The HAADF‐STEM intensity depends on sample thickness but also scales with the atomic number Z and therefore, chemical compositions can be studied from these three‐dimensional (3D) reconstructions.[1] Nevertheless, it is not straightforward to interpret the gray levels in a 3D HAADF‐STEM reconstruction, when mixing of elements is expected or elements with atomic number Z close to each other are present.
In an increasing number of recent studies, X‐ray Energy Dispersive Spectroscopy (XEDS) has been combined with tomography to understand complex nanostructure morphology and composition in 3D.[2] These studies rely on newly developed XEDS detectors such as the Super‐X detection system, which consists of four individual detectors, symmetrically arranged around the TEM sample.[3] By using the Super‐X detector, one is able to overcome problems that were previously related to extreme shadowing of the XEDS signal caused by the sample‐detector configuration. Although this problem can be largely overcome, some shadowing effects remain, as illustrated in Figure 1. Since such shadowing effects vary for different tilt angles, the XEDS will also depend on the tilt angle and the projection principle for electron tomography is no longer fulfilled. Because of this problem and the low signal‐to‐noise ratio, typical of XEDS mapping, it remains challenging to obtain quantitative information by 3D XEDS and further progress is required.
Here, we propose an alternative approach to optimize the reconstruction of an XEDS tomography series by minimizing the impact of shadowing effects and improving the spatial resolution. The method is based on the synergistic combination of HAADF‐STEM tomography and XEDS quantitative mapping.[4‐5] HAADF‐STEM yields a relatively high signal‐to‐noise ratio, enabling an accurate reconstruction of the morphology. XEDS, on the other hand, yields chemical information, but the limited amount of data that can be usually collected, hampers a good morphological reconstruction. As a proof of principle, we apply our methodology to a nanostructure containing a mix of Au and Ag atoms. It should be mentioned that the approach we propose here enables quantitative 3D chemical characterization of a broad variety of nanostructures.
Cost effective implementation of nanoparticle size measurement for regulation purposes
Authors: Müller Philipp , Wohlleben Wendel , Wieczorek Thorsten , Wagner Thorsten 
Published: December 2016

While nano‐scaled intermediate and consumer products are omnipresent in many industries, a huge challenge consists in the development of methods that reliably identify, characterize and quantify nanomaterials both as a substance and in various matrices. For product registration purposes, the European Commission proposed a definition of nanomaterial [1] which requires a quantitative size determination of the primary particles of a sample down to sizes of 1 nm. According to [1] a material is defined as nano if 50% of the primary particles are observed to comprise a smallest dimension <100 nm. The NanoDefine project [5] was set up to develop and validate a robust, readily implementable and cost‐effective measurement approach to obtain a quantitative particle size distribution and to distinguish between nano and non‐nano materials according to the definition [1].
In the present study the mean particle size derived from Brunauer, Emmet, Teller (BET) surface measurement by gas adsorption is systematically compared with the particle size derived from TEM images by manual and automated image evaluation. A correlation between mean particle diameters of 10 different organic pigments is given in figure 1. Automated and manual image evaluation lead to consistent results for the D50 particle size (red and blue bars). Automated TEM image evaluation was accomplished by a software package developed within the NanoDefine project which will soon be available as public ImageJ‐Plugin [2,3]. Samples were carefully selected to represent typical organic pigment particles of different grinding degrees. Figure 2 shows TEM images of such a series of pigment grades. The red ellipses mark the result of the automated particle detection using direct ellipse fitting. The length of the minor axis of each ellipsis was taken as approximation for the particles minimum feret diameter.
In the present study a tiered approach for particle classification is proposed. BET measurements can be used for a coarse classification of the material including a categorization into nano/non‐nano [4]. The presented data help to define the thresholds for this surface‐based classification. Automated evaluation of TEM images improves this classification with reliable results for the number‐based particle distribution within some remaining constraints. The according limitations are elaborated in the present study by comparison with the D50 size values determined by manually evaluation of TEM images.
Imaging of deformation of a polypropylene separator due to immersion in electrolyte or due to heating
Authors: takata keiji 
Published: December 2016

Pore size of separators is one of the most important factors for Li‐ion batteries. The separator must electrically isolate the anode and the cathode of the battery, but should allow Li ions to pass through easily. Large pores degrade the extent of isolation but small pores degrade the permeability; thus, a balance is needed for optimal performance. The pore size of the separator is determined well before its incorporation into the battery, but the pore size may not be maintained in the electrolyte. We, therefore, observed the structures of the separator before and after immersion in the electrolyte.
Figures 1(a) and 1(b) show atomic force microscopy (AFM) images of a 25‐mm‐thick single‐layer polypropylene separator before and after immersion in the electrolyte, respectively. The figures clearly show the lamellar alignment and the the fibrillae between the lamellae. The spacing between the lamellar layers was around 0.8 mm before immersion, but expanded to 1.4 mm after immersion. The pores expanded like sponge when they immersed in the liquid electrolyte. Expansion of the separator occurs when it is bound tightly inside the battery. Thus, expansion of the pores of the separator must be considered while fabricating good batteries.
One of the most important abilities of the separator is a shutdown ability. When a large current flows between the electrodes, the resultant heating partially melts the separator, and fills the pores. As a result, Li ions cannot pass through the portion of the separator, and the large current is shut down. Thus, shutdown by melting of the separator is an important factor for safety. To investigate melting of the separator, we observed the separator while heating.
AFM images obtained at 398 K show the deformation of the separator. Expansion of the lamellar layers and the filled pores were imaged. The melting band normal to the lamellar layers was extended in the direction of the fibrillae. The melting bands should be formed by fusion of the fibrillae and lamellae, and by conjunction. Partial melting around 390 K is adequate for shutdown. These results prove the good performance of the separator.
Direct visualization and quantification of three‐dimensional ferritin crystallization on the nanoscale
Authors: Houben Lothar , Weissman Haim , Wolf Sharon , Rybtchinski Boris 
Published: December 2016

We present the proof of concept that a real space tomography approach can be used for the quantification of local ordering in tiny crystals of ferritin. This work is driven by the need for a fundamental understanding of crystal growth of weakly interacting proteins on a molecular level. At present, only tentative ideas exist about interactions in particular in solution and during crystallization. Offering simplicity and controllability the condensation of ferritin molecules from solution was chosen as an ideal system to get insight into the nucleation and crystallisation mechanism that leads to ordered crystals.
The approach involves cryo‐fixation of aging stages of ferritin condensation from solution and subsequent three‐dimensional scanning transmission electron miscoscopy (STEM) tomography (Fig. 1a). Cryo‐STEM tomograms were recorded and analysed to yield the three‐dimensional ferritin particle coordinates for the real‐space refinement of the structure of ferritin agglomerates. 3D pair correlation functions for ordered nanocrystals of a few hundred ferritin particles reproduce well and up to higher coordination shells the crystal structure that was reported from synchrotron experiments on macrocrystals. The local order within ferritin agglomerates is further refined quantitatively by order parameter mapping with the resolution of a single lattice site based on a data‐base correlation technique (Fig. 1b).
UHVEM
observation for the dual structure in spheroidal graphite of cast irons
Authors: Maeda Hidefumi , Inoue Kanako , Sugiyama Akira , Yasuda Hidehiro 
Published: December 2016

The phenomenon that spheroidal graphite cast iron was formed by adding magnesium (Mg) was discovered in 1949 [1][2]. Since then, a number of researches have been made on this subject. Due partly to increase in research on the graphite‐spheroidizing, there are various theories such as interfacial energy theory, nuclear theory, bubble theory,,, etc. Among them interfacial energy theory is becoming dominant as of now [3]. However the role of Mg as the graphite‐spheroidizing agent has not been yet identified. And Mg particle is often observed inside of spheroidal graphite experimentally. In order to get the information on the internal structure of spheroidal graphite in cast iron, Ultra‐High Voltage Electron Microscopy (UHVEM) observation was carried out.
The composition of the cast iron in this experiment was FCD450 (Fe:Bal., C:3.645, Si:2.533, Mg:0.0464, Mn:0.368, P:0.018, S:0.0114, Cu:0.176 (wt%), Yodoshi Co.). The position of Mg in spheroidal graphite was predicted from a surface observation result by EPMA. Focused ion beam (FIB) cut out into approximately rectangular parallelepiped shape carbon sample from a spheroidal graphite of FCD450. This sample was observed by UHVEM in Osaka Univ. at 2.0MeV.
Figure 1 shows a bright field image (BFI) of the internal structure of spheroidal graphite. The electron beam in acceleration voltage of 2MeV was transmitted approximately 8μm thickness of graphite (inclination of the incident beam: 30°). Figure 1 indicated that whole area was graphite including the internal structure of spheroidal graphite roughly composed of a core region surrounded by annual rings of a layered intermediate region (central domain) and a layered outer region with some radial factors (covering domain).
Only the covering domain has the radial and superimposed contrast. This radial factor originates from the metal inclusion that grew radially from the central domain. The shape of the external region of the central domain (without superimposed contrast) could be regarded as the almost truth sphere, which might become core for growing graphite crystal spherically. Primary crystal of graphite might be spheroidized by the solidification in liquid state, and crystal growth of graphite reaches the eutectic point at the external region of the central domain. After that, the covering domain formed by the cooperation growth between graphite and austenite.
The spheroidal graphite in cast iron has the dual structure consisting of a spherical central domain and a covering domain. This obtained data using by UHVEM has provided new knowledge of the internal structure of spheroidal graphite in cast iron. And this study might provide important visual data to identify a role of the Mg in the graphite‐spheroidizing of cast iron.
In‐situ thermal measurements with high spatial resolution in the TEM
Authors: Voskanian Norvik , Cumings John , Olsson Eva 
Published: December 2016

With the constant miniaturization of electronics, the thermal management issue is becoming the main limiting factor in dictating device performance [1]. Therefore, the study of thermodynamics is of practical interest as well as fundamental scientific interest. However, measuring temperature at these dimensions is difficult due to the increasing influence of the employed measurement tools and therefore new techniques need to be developed. One such technique, Electron Thermal Microscopy (EThM), has been previously used to study heat dissipation in nanowires and carbon nanotubes supported on SiN substrate [3, 4].
EThM is an in‐situ thermal imaging technique using the Transmission Electron Microscope (TEM) and relies on the observation of the solid to liquid phase transition of indium islands and provides a binary temperature map with 50nm spatial resolution[2]. The indium islands, thermally evaporated on the back of the substrate, as seen in the bright‐field TEM image in Figure 1a, melt once heated to 429K. This solid to liquid phase transition is easily observed in the TEM, when operating in the appropriate dark‐field conditions (Figure 1b), at which the molten islands appear bright compared to the solid ones. In addition, the presence of a high melting point thin oxide layer on the indium preserves the structure of the islands and allows the thermometry technique to be used repeatedly over a large experimental range.
Two factors contribute to the observed temperature of the system; the heat source and the efficiency of the heat transfer mechanism to the lower temperature reservoir. Here we present the work on joule heated Pd nanowires supported on SiN substrate and use the EThM technique to evaluate the thermal properties of the device. The measured temperature and the efficiency of the heat transfer mechanism can be quantified in terms of the thermal conductivity of the different materials within the device and their thermal boundary resistances. Conventionally, the thermal transport in dielectrics, such as SiN, is phonon mediated. However, as the dimensions approach the mean free path of the phonons, new modasses of heat dissipation may dominate. Combining our experimental thermal measurements (Figure 1c) with simulations (Figure 1d), based on finite element analysis, we have explored different modes of thermal transport and show that the conventional phonon mediated thermal transport is not sufficient to explain the observed temperature gradient across the SiN, indicating that an additional mode is active.
Mapping the plasmonic modes of silver nanoparticle aggregates
Authors: Diaz‐Egea Carlos , Abargues Rafael , Martínez‐Pastor Juan P , Sigle Wilfried , van Aken Peter A. , Molina Sergio I 
Published: December 2016

The optical properties of the noble metal nanoparticles (NPs) are dominated by localized surface plasmon resonances (LSPR) [1]. A spherical NP suspended in vacuum would present a LSPR mode that can be modelled as a dipole, hence called dipolar mode. When NPs are close enough to each other, they couple splitting the plasmonic modes of the same order and creating two new modes, the bonding dipolar plasmonic mode (BDP), and the antibonding dipolar plasmonic mode (ADP) [2]. The BDP is a low‐energy mode while the ADP resonates at a value slightly higher than the dipolar mode of a sphere. The exact energy value for both modes depends on the inter‐particle distance, being smaller as they are closer to each other [3]. It also depends on the aspect ratio of the group with lower energy values as the aspect ratio gets larger [4]. The third conditioning factor is the geometric shape of the cluster. In the same way that triangular NPs have plasmonic modes at lower energies than a sphere [5], a triangular or rhomboidal shaped group of NPs shows plasmonic modes at smaller energies than a spherical one [6].
In this work, silver NPs were created and were forced to cluster. Samples were taken at different stages of the aggregation process. They were analyzed at a large scale by UV‐Vis spectroscopy (UV‐Vis) and at nanometre scale by energy‐filtering transmission electron microscopy (EFTEM). The individual, dipolar mode was clearly identified for isolated NPs corresponding to the early stages of the clustering process. As bigger clusters are created, the collective modes become more apparent.
This work was supported by the Spanish MINECO (projects TEC2014‐53727‐C2‐1‐R, 2‐R and CONSOLIDER INGENIO 2010 CSD2009‐00013), Generalitat Valenciana (PROMETEOII/2014/059) and Junta de Andalucía (PAI research group TEP‐946). The research leading to these results has received funding from the European Union Seventh Framework Program [FP/2007/2013] under Grant Agreement No. 312483 (ESTEEM2) and H2020 Program (PROMIS ITN European network).
Novel in vivo imaging techniques to visualise renal morphology and function in acute kidney injury
Authors: Liang Xiaowen , Wang Haolu , Gravot Germain , Liu Xin , Roberts Michael 
Published: December 2016

Introduction

The medical uses of optical imaging are revolutionizing medicine; optical imaging is undergoing explosive growth fuelled by advances in high‐sensitivity detectors. These light based systems utilise multiphoton microscopy (MPM) to provide high resolution and quantitative imaging of cellular metabolism in
in situ
and
in vivo
biological tissues and organs – in space (three dimensions), in time, in spectra, and in fluorescence anisotropy (i.e. a total of 6 dimensions). MPM allows
in vivo
visualisation of intact kidney tissue at the single cell resolution, which is solved a long‐standing critical technical barrier in renal research to study several complex and inaccessible cell types and anatomical structures. In this study, MPM was employed to visualise morphology changes and study the functions of acute kidney injury (AKI).

Methods
Glycerol‐inducedAKI model (elevated serum creatinine) can be used to mimic rhabdomyolysis, which was developed in male C57BL/6 mice (8–12 weeks) byintramuscular injection of50% (v/v) glycerol /PBS (10 ml/kg) into the left hind leg. The control mice were injected by PBS using the same method. After 24 hours, kidneys were exposed to image using MPM for morphology examination in both groups. Since Rhodamine 123 (RH123) is a marker to measure P‐glycoprotein (P‐gp) transporter function, it was intravenously injected into control and AKI mice and imaged by MPM to evaluate the P‐gp transporter function. Using a bolus injection of FITC labelled inulin, rapid quantification of glomerular filtration rate (GFR) was determined in both groups by directly imaging of inulin clearance from glomerulus. A LaVision Biotec Nikon MPM was used to image RH123 excretion from tubules. GFR was measured using a DermanInspect system equipped with the ultrashort (85 fs pulse width, 80 MHz repetition rate) pulsed mode‐locked tunable Ti:sapphire laser (Mai Tai, Spectra Physics, 25 Mountain View, USA).

Results
The MPM imagesdirectly showed morphology changes in AKI mice compared to control group, where acute injury of tubular cells as indicated by reduced autofluorescence and cellular vacuolation (Fig.1). Intravital imaging showed that RH123 was rapidly excreted from tubules in control group but slowly eliminated from AKI model (Fig. 2), indicating P‐gp transporter dysfunction in glycerol‐induced AKI. As shown in Fig, 3, reduced glomerular permeability was also observed in AKI model, where FITC‐labelled inulin (red color) was quickly cleared from glomerular at 30 mins after injection in control group, while fluorescence from FITC‐labelled inulin was retained in glomerular in AKI model.

Conclusion
This advanced imaging techniquecan be used to rapiddiagnosis and quantification of AKIinduced morphology andfunctional changes.