bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of elemental composition of Fe1‐xNix and Si1‐xGex alloy thin films by electron probe microanalysis and micro‐focus X‐ray fluorescence
Authors: Hodoroaba Vasile‐Dan , Terborg Ralf , Boehm Stephan , Kim Kyung Joong
Published: June 2020

The present study reports on results of analysis of the elemental composition of thin films by electron probe microanalysis with energy dispersive (ED‐EPMA) X‐ray spectrometry in conjunction with the dedicated thin‐film analysis software package Stratagem and by X‐ray fluorescence in its version with a micro‐focus X‐ray fluorescence (μ‐XRF) source attached to a scanning electron microscope (SEM). Two thin‐film systems have been analyzed: Fe1‐xNix on silicon wafer and Si1‐xGex on Al2O3 substrate, in both cases the layers being grown to a thickness of about 200 nm by ion beam sputter deposition. Samples of five different atomic fractions have been produced and analyzed for each thin‐film system. Moreover, reference samples with certified elemental composition and thickness have been also available. This study is part of an interlaboratory comparison organized in the frame of standardization technical committee ISO/TC 201 “Surface chemical analysis.” Two laboratories have been analyzed by ED‐EPMA (one laboratory standardless and one laboratory using both standardless and with standards variants) and one laboratory by μ‐XRF (standardless and with standards). All the elemental compositions obtained with different methods are in very good agreement for the complete two sets of five samples each.
Effect of Ball Milling and Oxidation on Dispersibility and Dispersion Stability of Multiwalled Carbon Nanotubes in High Viscous Heat Exchange Fluids
Authors: Vishal Chachin , Raju Chinthalapati Siva Kesava , Krishna Kanala Raghava , Raman Ravishankar , Rao Bojja Ramachandra , Kanaparthi Ramesh
Published: June 2020

Multiwalled carbon nanotubes (MWCNTs) tend to agglomerate resulting in poor dispersion in most of the common solvents due to possessing long tubular structure, high Vander Waal force of attractions and poor interfacial interactions with the surrounding matrix. To improve the dispersion stability, MWCNT, were subjected to ball milling with 300 rpm for 1 h to reduce the length of the MWCNT to improve the functional groups to the MWCNT wall during chemical functionalization. MWCNTs were subjected to thermal oxidation in air at different temperatures before acid treatment to remove the amorphous carbon from MWCNT. Morphology studies of MWCNTs nanofluids were carried out by using a SEM and TEM methods to characterize the surface deformity of MWCNT structure and extent of defect formation, respectively. FT IR and XRD methods were used for the identification of different functional groups and crystalline nature of pristine, ball milled and oxidized MWCNT, respectively. Raman spectroscopy was applied to measure the relative intensities (ID/IG) to estimate the defect ratios. Preparation of nanofluid by dispersing high defect ratio MWCNTs with a concentration of 100 ppm in the base fluid by the ultra‐sonication method. Nanofluids dispersion stability and cycle stability were studied by using UV‐Visible spectroscopy and MWCNTs treated with combined ball milling and oxidation method have exhibited high stability and high dispersibility.
Novel γ‐Al2O3 Supported Low Concentrated Pd Nanoalloy Catalyst for Improved Hydrogenation Ability of 2‐Methylfuran
Authors: Shang Fangfang , Yu Haoxuan , Chu Qingyan , Yang Haiyu , Wang Ping , Cui Hongyou , Wang Ming
Published: June 2020

Pd−Al was constructed to deal with the issue that cyclic unsaturated compounds are unstable in hydrogenation reaction. Hydrogenation of 2‐methylfuran as a probe reaction in the fixed‐bed reactor afforded up to 99.9% yield and 100% chemo‐selectivity requiring only 100 °C and 2 MPa pressure. Compared with the previous hydrogenation catalyst, such as Ni based catalyst, Pd−Al nanoalloy catalyst employs better performance. Enhancement of catalytic activity, selectivity and stability was attributed to the construction of nano‐effect and Pd−Al alloy structure with low loading amount of Pd. Furthermore, Pd−Al nanoalloy catalyst presented excellent catalytic stability in hydrogenation reaction running for 150 h. Finally, a feasible mechanism of the reaction was proposed and proved by collecting intermediate.
Preparation of Maleimide‐Based Enediynes with Propargyl Ester for Efficient Tumor Cell Suppression
Authors: Chen Huimin , Li Baojun , Zhang Mengsi , Lu Haotian , Wang Yue , Wang Wenbo , Ding Yun , Hu Aiguo
Published: June 2020

Acyclic enediynes are much easier to be synthesized comparing to natural or synthetic cyclic enediynes. However, the conditions for their thermal reactions to produce free radicals through Bergman cyclization (BC) are typically demanding, limiting their applications as antitumor agents. On the other hand, the acyclic compounds with enyne‐allene structures prone to proceed through Myers‐Saito cyclization (MCS) under much milder conditions. Therefore, it is vital to design acyclic enediynes which can permit propargyl‐allenyl rearrangement and then undergo MSC at low temperature for antitumor applications. In this work, we synthesized a series of maleimide‐based enediyne compounds with propargyl ester functionalities. The facile propargyl‐allenyl tautomerization assisted by the maleimide group enabled the formation of enyne‐allene structures and the subsequent occurrence of MSC. The generation of free radicals, which further raised the reactive oxygen species level in physiological environments, was confirmed by electron paramagnetic resonance analysis. The highly reactive radicals showed excellent DNA‐cleaving ability as confirmed with DNA gel electrophoresis. In addition, this kind of acyclic enediynes effectively inhibited the proliferation of HeLa cells with half inhibition concentration down to submicromolar level, comparable or even superior to many clinically used antitumor agents, showing promising application aspect.
Gluconate‐Stabilized Silver Nanoparticles as pH Dependent Dual‐Nanosensor for Quantitative Evaluation of Methionine and Cysteine
Authors: Khan Shamim Ahmed , Choudhury Rupasree , Majumdar Moumita , Nandi Nishithendu Bikash , Roy Shaktibrata , Misra Tarun Kumar
Published: June 2020

Silver nanoparticles (AgNPs) based naked‐eye and spectrophotometric dual‐nanosensor for two most important biothiols: methionine and cysteine would be highly useful for an analyst. We have explored potential use of gluconate‐stabilized AgNPs (Glu‐AgNPs) for such unique purpose. Simply, aggregation of Glu‐AgNPs by the analyte, methionine/cysteine technique was adopted. Gluconate ions make the AgNPs anionic in nature. The anionic Glu‐AgNPs, as a pH‐ dependent nanosensor are selective to sensing methionine and cysteine over other amino acids in aqueous solution. By tuning pH of the particles’ solution we have at different demonstrated that the equilibria components of methionine/cysteine at different pH may play guiding roles in aggregating the particles, consequently in selectivity and sensitivity of the nanosensor. The LOL, LOQ, and LOD for methionine are 42, 9.89 and 2.97 μM, and for cysteine are 1.4, 0.49 and 0.14 μM, respectively. The interactions of cysteine (Kasso, 3.07x105 M−1) with the anionic Glu‐AgNPs are greater than that of methionine (Kasso, 1.635x104 M−1). Overall, the recovery results from the real samples: urine, blood serum and aCsF are excellent, which may make the developed nanosensor attractive to an analyst.
Peroxy‐Benzoic Acid Mediated Domino C[sp2] Hydroxylation /Annulation of Enaminones for the Synthesis of 3‐Hydroxy Chromones
Authors: Gudipati Ramakrishna , Kandula Venu , Raghavulu K. , Basavaiah K. , Yennam Satyanarayana , Behera Manoranjan
Published: June 2020

An efficient, facile, and clean synthesis of various 3‐hydroxy‐chromones (3‐hydroxy‐4H‐chromene‐4‐ones) via enamino ketone followed by cyclization using m‐chloroperbenzoic acid (MCPBA) has been described. The significant features of this method include simple method, high purity and excellent regio‐selectivity of the products. This is the first report for the two step one pot synthesis of 3‐hydroxyl chromone using MCPBA.
In Situ Grown Single‐Atom Cobalt on Polymeric Carbon Nitride with Bidentate Ligand for Efficient Photocatalytic Degradation of Refractory Antibiotics
Authors: Yang Yang , Zeng Guangming , Huang Danlian , Zhang Chen , He Donghui , Zhou Chengyun , Wang Wenjun , Xiong Weiping , Song Biao , Yi Huan , Ye Shujing , Ren Xiaoya
Published: June 2020

Semiconductor photocatalysis is a promising technology to tackle refractory antibiotics contamination in water. Herein, a facile in situ growth strategy is developed to implant single‐atom cobalt in polymeric carbon nitride (pCN) via the bidentate ligand for efficient photocatalytic degradation of oxytetracycline (OTC). The atomic characterizations indicate that single‐atom cobalt is successfully anchored on pCN by covalently forming the CoO bond and CoN bond, which will strengthen the interaction between single‐atom cobalt and pCN. This single‐atom cobalt can efficiently expand optical absorption, increase electron density, facilitate charge separation and transfer, and promote OTC degradation. As the optimal sample, Co(1.28%)pCN presents an outstanding apparent rate constant for OTC degradation (0.038 min−1) under visible light irradiation, which is about 3.7 times than that of the pristine pCN. The electron spin resonance (ESR) tests and reactive species trapping experiments demonstrate that the 1O2, h+, •O2−, and •OH are responsible for OTC degradation. This work develops a new way to construct single‐atom‐modified pCN and provides a green and highly efficient strategy for refractory antibiotics removal.
Synthesis, Structures, and Antibacterial Activities of Four Similar 1D Metal‐organic Polymers with Different Metal Ions
Authors: Wang Yufei , Khan Misbha Rafiq , Niu Xiaoge , Zhang Wenjing , Li Yulin , Li Bohan , Hao Yaping , Li Jinpeng , Liu Zhongyi
Published: June 2020

Four similar 1D metal‐organic polymers [Cd(impc)2(H2O)2]n (1), [Co(impc)2(H2O)2]n (2), [Mn(impc)2(H2O)2]n (3), and {[Cu(impc)2]·[jy2H2O}n (4) based on an asymmetric 5‐(1H‐imidazole‐l‐yl)‐3‐pyridinecarboxylic acid (Himpc) were prepared hydrothermally and structurally characterized. According to the frontier molecular orbital (FMOs) calculations, the photoluminescence of 1 should be assigned as the n→π* transition. The antibacterial properties of 1–4 were studied. 1 exhibited good antibacterial activities towards B. subtilis and S. aureus with the smallest MIC value of 2 μg·mL–1. Compared with CoII, MnII and CuII ions, the polymer with CdII ion has the better antibacterial activity. Our work preliminarily reveals that the metal ions also have different influences on antibacterial activities of complexes.
Preparation and Crystal Structure of a New Uranyl Sulfate Templated by a Bis‐isothiouronium Cation
Authors: Charkin Dmitri O. , Bezzubov Stanislav I. , Siidra Oleg I. , Borisov Artem S. , Kalmykov Stepan N.
Published: June 2020

Crystals of a new uranyl sulfate (C2N4H8S2)[UO2(SO4)2]·0.3H2O (1) templated by a relatively rare bis‐isothiouronium cation, were formed upon evaporation of aqueous solutions containing uranyl acetate, thiourea, and excess sulfuric acid. The new compound is orthorhombic, P212121, a = 6.928(2) Å, b = 13.398(3) Å, c = 15.225(3) Å, Z = 2. Its crystal structure is comprised of [UO2(SO4)2] moieties linked by hydrogen bonds formed between the template cations and terminal oxygen atoms of the sulfate tetrahedra. The C2N4H8S22+ template is most likely formed in situ during a redox reaction between uranyl cation and thiourea in a strongly acidic medium, with UO22+ partially reduced to U4+.
Spectral Field Campaigns: Planning and Data Collection
Authors: Schweiger Anna K.
Published: June 2020

This chapter focuses on planning field campaigns and data collection relevant to plant biodiversity. Particular emphasis is placed on sampling spectra of plants across scales, from the leaf to the canopy and airborne level, considering the issue of matching ecological data with spectra. The importance of planning is highlighted from the perspective of the long-term sustainability of a project, which includes using and contributing to the development of standards for project documentation and archiving. These issues are critical to biodiversity researchers involved in data collection in situ and via remote sensing (RS).
Phase transitions in a three-dimensional analogue of Klebanov-Strassler
Authors: Elander Daniel , Faedo Antón F. , Mateos David , Subils Javier G.
Published: June 2020

Abstract

We use top-down holography to study the thermodynamics of a one-parameter family of three-dimensional, strongly coupled Yang-Mills-Chern-Simons theories with M-theory duals. For generic values of the parameter, the theories exhibit a mass gap but no confinement, meaning no linear quark-antiquark potential. For two specific values of the parameter they flow to an infrared fixed point or to a confining vacuum, respectively. As in the Klebanov-Strassler solution, on the gravity side the mass gap is generated by the smooth collapse to zero size of a cycle in the internal geometry. We uncover a rich phase diagram with thermal phase transitions of first and second order, a triple point and a critical point.
Dark photon dark matter in the presence of inhomogeneous structure
Authors: Witte Samuel J. , Rosauro-Alcaraz Salvador , McDermott Samuel D. , Poulin Vivian
Published: June 2020

Abstract

Dark photon dark matter will resonantly convert into visible photons when the dark photon mass is equal to the plasma frequency of the ambient medium. In cosmological contexts, this transition leads to an extremely efficient, albeit short-lived, heating of the surrounding gas. Existing work in this field has been predominantly focused on understanding the implications of these resonant transitions in the limit that the plasma frequency of the Universe can be treated as being perfectly homogeneous, i.e. neglecting inhomogeneities in the electron number density. In this work we focus on the implications of heating from dark photon dark matter in the presence of inhomogeneous structure (which is particularly relevant for dark photons with masses in the range 10
−15 eV ≲ m

A′
≲ 10
−12 eV), emphasizing both the importance of inhomogeneous energy injection, as well as the sensitivity of cosmological observations to the inhomogeneities themselves. More specifically, we derive modified constraints on dark photon dark matter from the Ly-α forest, and show that the presence of inhomogeneities allows one to extend constraints to masses outside of the range that would be obtainable in the homogeneous limit, while only slightly relaxing their strength. We then project sensitivity for near-future cosmological surveys that are hoping to measure the 21cm transition in neutral hydrogen prior to reionization, and demonstrate that these experiments will be extremely useful in improving sensitivity to masses near ∼ 10
−14 eV, potentially by several orders of magnitude. Finally, we discuss implications for reionization, early star formation, and late-time y-type spectral distortions, and show that probes which are inherently sensitive to the inhomogeneous state of the Universe could resolve signatures unique to the light dark photon dark matter scenario, and thus offer a fantastic potential for a positive detection.
The monodromy groups of lisse sheaves and overconvergent F-isocrystals
Authors: D’Addezio Marco
Published: June 2020

It has been proven by Serre, Larsen–Pink and Chin, that over a smooth curve over a finite field, the monodromy groups of compatible semi-simple pure lisse sheaves have “the same” $$\pi _0$$

π
0

and neutral component. We generalize their results to compatible systems of semi-simple lisse sheaves and overconvergent F-isocrystals over arbitrary smooth varieties. For this purpose, we extend the theorem of Serre and Chin on Frobenius tori to overconvergent F-isocrystals. To put our results into perspective, we briefly survey recent developments of the theory of lisse sheaves and overconvergent F-isocrystals. We use the Tannakian formalism to make explicit the similarities between the two types of coefficient objects.
Analyse der Spontanmotorik im 1. Lebensjahr: Markerlose 3-D-Bewegungserfassung zur Früherkennung von Entwicklungsstörungen
Authors: Parisi Carmen , Hesse Nikolas , Tacke Uta , Pujades Rocamora Sergi , Blaschek Astrid , Hadders-Algra Mijna , Black Michael J. , Heinen Florian , Müller-Felber Wolfgang , Schroeder A. Sebastian
Published: June 2020

Kinder mit motorischer Entwicklungsstörung profitieren von einer frühen Entwicklungsförderung. Eine frühe Diagnosestellung in der kinderärztlichen Vorsorge (U2–U5) kann durch ein automatisiertes Screening verbessert werden. Bisherige Ansätze einer automatisierten Bewegungsanalyse sind jedoch teuer und aufwendig und nicht in der Breite anwendbar. In diesem Beitrag soll ein neues System zur Videoanalyse, das Kinematic Motion Analysis Tool (KineMAT) vorgestellt werden. Es kann bei Säuglingen angewendet werden und kommt ohne Körpermarker aus. Die Methode wird anhand von 7 Patienten mit unterschiedlichen Diagnosen demonstriert.

Mit einer kommerziell erhältlichen Tiefenbildkamera (RGB-D[Red-Green-Blue-Depth]-Kamera) werden 3‑minütige Videosequenzen von sich spontan bewegenden Säuglingen aufgenommen und mit einem virtuellen Säuglingskörpermodell (SMIL[Skinned Multi-infant Linear]-Modell) in Übereinstimmung gebracht. Das so erzeugte virtuelle Abbild erlaubt es, beliebige Messungen in 3‑D mit hoher Präzision durchzuführen. Eine Auswahl möglicher Bewegungsparameter wird mit diagnosespezifischen Bewegungsauffälligkeiten zusammengeführt.

Der KineMAT und das SMIL-Modell erlauben eine zuverlässige, dreidimensionale Messung der Spontanaktivität bei Säuglingen mit einer sehr niedrigen Fehlerrate. Basierend auf maschinellen Lernalgorithmen kann der KineMAT trainiert werden, pathologische Spontanmotorik automatisiert zu erkennen. Er ist kostengünstig und einfach anzuwenden und soll als Screeninginstrument für die kinderärztliche Vorsorge weiterentwickelt werden.
Resistance of different wood-based materials against mould fungi: a comparison of methods
Authors: Imken Arne A.P. , Brischke Christian , Kögel Sebastian , Krause Kim C. , Mai Carsten
Published: June 2020

Wood-based materials are generally prone to colonization by mould fungi and other discoloring microorganisms, but their resistance to fungal discoloration varies. Different standardized test methods for determining the susceptibility to mould fungi have been used to evaluate various wood-based materials, but the obtained results suggest that mould resistance depends on the method applied. Therefore, this study aimed at a comparative evaluation of two commonly used methods for determining the mould resistance of wood-based materials, i.e. the chamber method according to BS 3900—Part G6 and the malt agar plate method according to ISO 16869. Solid wood, wood fiber insulation boards and wood polymer composites were inoculated, incubated for different time intervals, and assessed with regard to superficial mould growth. Mould growth ratings obtained with the two methods did not correlate well, neither within one type of material nor across different materials, which can be attributed to higher moisture contents and additional nutrients available for the specimens in the agar plate test compared to those in the chamber test. It was concluded, that the experimental set up could have an overriding effect on the results of mould resistance tests.
Development of a capillary electrophoresis–mass spectrometry method for the analysis of metformin and its transformation product guanylurea in biota
Authors: Knoll Sarah , Jacob Stefanie , Mieck Susanna , Triebskorn Rita , Braunbeck Thomas , Huhn Carolin
Published: June 2020

A method with capillary electrophoresis coupled to mass spectrometry was optimized to determine the uptake of metformin and its metabolite guanylurea by zebrafish (Danio rerio) embryos and brown trout (Salmo trutta f. fario) exposed under laboratory conditions. Metformin was extracted from fish tissues by sonication in methanol, resulting in an absolute recovery of almost 90%. For the extraction of guanylurea from brown trout, solid-phase extraction was implemented with a recovery of 84%. The use of a mixture of methanol and glacial acetic acid as a non-aqueous background electrolyte was vital to achieve robust analysis using a bare fused-silica capillary with an applied voltage of +30 kV. Problems with adsorption associated with an aqueous background electrolyte were eliminated using a non-aqueous background electrolyte made of methanol/acetic acid (97:3) with 25 mM ammonium acetate (for zebrafish embryos) or 100 mM ammonium acetate (for brown trouts), depending on the sample complexity and matrix influences. High resolution and high separation selectivity from matrix components were achieved by optimization of the ammonium acetate concentration in the background electrolyte. An extensive evaluation of matrix effects was conducted with regard to the complex matrices present in the fish samples. They required adapting the background electrolyte to higher concentrations. Applying this method to extracts of zebrafish embryos and brown trout tissue samples, limits of detection for both metformin and guanylurea in zebrafish embryos (12.2 μg/l and 15 μg/l) and brown trout tissues (15 ng/g and 34 ng/g) were in the low μg/l or ng/g range. Finally, metformin and guanylurea could be both quantified for the first time in biota samples from exposure experiments.
Work above shoulder level and shoulder complaints: a systematic review
Authors: Wærsted Morten , Koch Markus , Veiersted Kaj Bo
Published: June 2020

Objective

To investigate the association and the exposure–response relationship between work above shoulder height and shoulder pain or disorders.

Methods

A systematic search was performed in Medline, Embase, and Health and Safety Science Abstracts. Included were articles with prospective cohort, case–control, cross-sectional, or intervention study designs. Quality assessment was based on an evaluation scheme adjusted to study design and normalized to 100%. The cut-off for sufficient quality to include articles was above 40% and cut-off for high-quality articles was above 50% of maximal score. The level of strength of evidence for an association between exposure and effect was assessed according to the GRADE guidelines.

Results

Thirty-four articles were included. Articles that document large effects (higher risk estimates; OR ≥ 2) have higher quality score, include analyses of severe arm elevation, more often use clinical outcome, and report an exposure–response relationship compared to studies reporting lower risk estimates. The studies that reported large effects were all significant.

An exposure–response relationship was found in many high-quality studies when relating exposure intensity of arm elevation (level of arm elevation, amplitude) as well as duration of arm elevation, especially > 90°.

Conclusion

We conclude on a limited evidence for an association between arm elevation at work and shoulder disorders. Severe arm elevation with elbows above shoulder level (i.e., > 90°) shows a moderate evidence for an association with shoulder disorders.
Evidence for 9R-SiC?
Authors: Kaiser U. , Chuvilin A. , Kyznetsov V. , Butenko Y.
Published: June 2020

Complementary to our first paper on the origin of threefold contrast on SiC high resolution transmission electron microscopy (HRTEM) images, we now provide an example of threefold contrast produced by a stacking layer sequence which corresponds to one unit cell of the 9R polytype.
Scattering Cross Sections in Electron Microscopy and Analysis
Authors: Rez Peter
Published: June 2020

The scattering cross section is the fundamental measure of the strength of a scattering interaction. All scattering in electron microscopy arises from the Coulomb interaction, and scattering cross sections, whether elastic or inelastic, will therefore all have common features. Simple forms of both elastic and inelastic cross sections are reviewed in the context of high resolution and analytical microscopy. Some recent developments, such as the calculation of Fano resonances in electron energy loss spectra of transition metals and rare earth elements are also discussed.
Differential Image Distortion Correction
Authors: Pollak C. , Stubbings T. , Hutter H.
Published: June 2020

Imaging techniques often suffer from distortion effects. Former methods of reducing these distortions have been based either on improving the imaging technique (i.e., to avoid distortions) or on the use of reference samples (i.e., to determine the distortion field by imaging of a known structure. We present a novel method of correcting image distortion by evaluating the imaged position changes due to two small sample position shifts. The algorithm allows us to calculate a vector field, which enables us to determine the “undistorted” position of any point of the image. The presented method has very low presuppositions about the sample, requires no reference samples, and is applicable to any type of image distortion. In addition to the presentation of the method's theoretical basis and a description of the computational method, we present corrected secondary ion mass spectroscopy (SIMS) images of a regular structure (a copper grid) as well as a stochastic distribution (sodium impurities) to show the results of empirical data.
Electron Beam Current Loss at the High-Vacuum– High-Pressure Boundary in the Environmental Scanning Electron Microscope
Authors: Danilatos Gerasimos D. , Phillips Matthew R. , Nailon John V.
Published: June 2020

A significant loss in electron probe current can occur before the electron beam enters the specimen chamber of an environmental scanning electron microscope (ESEM). This loss results from electron scattering in a gaseous jet formed inside and downstream (above) the pressure-limiting aperture (PLA), which separates the high-pressure and high-vacuum regions of the microscope. The electron beam loss above the PLA has been calculated for three different ESEMs, each with a different PLA geometry: an ElectroScan E3, a Philips XL30 ESEM, and a prototype instrument. The mass thickness of gas above the PLA in each case has been determined by Monte Carlo simulation of the gas density variation in the gas jet. It has been found that the PLA configurations used in the commercial instruments produce considerable loss in the electron probe current that dramatically degrades their performance at high chamber pressure and low accelerating voltage. These detrimental effects are minimized in the prototype instrument, which has an optimized thin-foil PLA design.
Design and Applications of Environmental Cell Transmission Electron Microscope for In Situ Observations of Gas–Solid Reactions
Authors: Sharma Renu
Published: June 2020

The environmental transmission electron microscopy (E-TEM) is a budding technique for in situ study of gas–solid chemical reactions with numerous applications. Recent improvements in the design have made it possible not only to obtain atomic level information but also the chemical information during the reaction by incorporating an imaging filter or electron energy-loss spectrometer to an E-TEM. We have been involved in modifying a couple of microscopes to incorporate environmental cells in order to convert them into E-TEMs. These microscopes have been used to obtain atomic level information of the structural and chemical changes during dynamic processes by in situ electron diffraction, high-resolution imaging, and electron energyloss spectroscopy. The applications include, but are not limited to, oxidation, reduction, polymerization, nitridation, dehydroxylation, hydroxylation, chemical vapor deposition, etc. We report recent developments in the design and application along with the limitations of an E-TEM.
Site-specific Transmission Electron Microscope Characterization of Micrometer-sized Particles Using the Focused Ion Beam Lift-out Technique
Authors: Lomness Janice K. , Giannuzzi Lucille A. , Hampton Michael D.
Published: June 2020

Micrometer sized particles have been studied to show that a high-quality transmission electron microscope (TEM) specimen can be produced, without the use of embedding media, from a site-specific region of chosen particles using the focused ion beam (FIB) lift-out (LO) technique. The uniqueness of this technique is that site-specific TEM LO specimens may be obtained from particles and from regions which are smaller than the conventional ∼10–20 μm × 5 μm × ∼0.1 μm dimensions of the LO specimen. The innovative FIB LO procedures are described in detail and TEM images of electron transparent specimens obtained from specific micrometer-sized particles are presented.
Atomic-scale Study of a Transition Phase Precipitate and Its Interfacial Chemistry in an Fe−15 at.% Mo−5 at.% V Alloy
Authors: Isheim Dieter , Hellman Olof C. , Seidman David N. , Danoix Frédéric , Bostel Alain , Blavette Didier
Published: June 2020

A Mo-rich precipitate in an Fe-rich matrix and the heterophase interface bounding the precipitate have been examined on an atomic scale by three-dimensional atom-probe (3DAP) microscopy and transmission electron microscopy (TEM). The Mo-rich precipitate was generated by isothermal solid-state decomposition at 500°C of an Fe-15 at.% Mo-5 at.% V alloy. After this heat treatment, TEM reveals a characteristic modulated strain contrast structure. The precipitate has a composition of Mo-13.0 at.% Fe-4.9 at.% V as measured by 3DAP microscopy. The alloy decomposes at a nearly constant 5 at.% V, constituting a metastable tie-line between Fe-rich and Mo-rich bcc solid solutions. The formation of the equilibrium intermetallic phases is kinetically impeded. A local vanadium enrichment of 21 at.% is detected at the interface of the precipitate in a matrix region about 0.27 nm or 1–2 atomic layers in thickness. The corresponding value of the Gibbsian interfacial excess of vanadium is 3.3 ± 1.3 nm−2.
Atomic Force Microscopy and Scanning Electron Microscopy Reveal Genome–dependent Ultrastructure of Seed Surface
Authors: Guha T. , Bhar R. , Ganesan V. , Sen A. , Brahmachary R.L.
Published: June 2020

Both scanning electron microscopy (SEM) and contact mode imaging via atomic force microscopy (AFM) have been utilized to elucidate the ultrastructure of mung bean seed surfaces. The results indicate: 1) that AFM is useful in the examination of seed surface ultrastructure ex-vaccuo without the need for additional complex preparative procedures; and 2) that both the cotyledon and seed coat of different strains of mung beans bear specific ultrastructural details unique to each strain. To our knowledge, these are the first AFM images of seed surfaces.
Nondestructive Angle-resolved X-ray Depth Profiling: Interpretation of Angle-resolved Profiles Using a Monte Carlo Approach
Authors: Wilkinson David K. , Loveday Daniel A. , Prutton Martin
Published: June 2020

A technique has been developed for the interpretation of composition-depth profiles from angleresolved X-ray data using a Monte Carlo electron scattering simulation. This is a nondestructive depth profiling procedure. Software has been developed that uses a Monte Carlo scattering simulation to generate the signal intensity from a multilayer sample for any combination of primary beam angle of incidence and take-off angle to the X-ray detector. An interactive C++ application uses this simulation to interpret measured angle-resolved depth profiles. The method has been tested using a custom-made Ag/Al “staircase” sample containing two layers each of Ag and Al. Using the technique, it is possible to quantify the composition-depth profile for the two- and three-layer “steps” of the sample. Qualitative information may be gained about the four-layer area of the sample.
A Few Examples of Electron Microanalysis of Art Objects at the Boston
Museum of Fine Arts
Authors: Ogilvie Robert E.
Published: June 2020

Examples of a few objects are presented, where the electron microprobe
has proved that it can provide the conservator and the curator with
information that will help in evaluating the authenticity of a particular
art object. They will also obtain a better understanding of how an object
was fabricated and what materials it was made from. The results of the
analysis of paint samples, samples from metal artifacts, as well as
specimens from marble sculptures, are described.
X-ray Crystal Spectrometers and Monochromators in Microanalysis
Authors: Wittry David B. , Barbi Nicholas C.
Published: June 2020

Castaing’s successful implementation and application of the electron
probe microanalyzer in 1950 stimulated a flurry of development activity
around the world. The later versions of this instrument represented a truly
international effort, with significant contributions by scientists from
Europe, Asia, and North America. If the probe-forming system of the
instrument was its heart, the X-ray wavelength spectrometer was its soul.
This article reviews some of the history of spectrometer
developments—lthrough the “golden years” of microprobe development, namely
the dozen or so years following the publication of Castaing’s thesis, to the
present. The basic physics of spectrometer and crystal design is reviewed.
Early experimental devices, such as those developed by Castaing, Borovskii,
Wittry, Duncumb, and Ogilvie are reported. Examples of commercial
spectrometers such as those by ARL, MAC, Microspec, and Peak are described.
Recent developments such as the combination of grazing-incidence optics with
flat crystal spectrometers are noted, and the properties and uses of doubly
curved crystals are discussed. Finally, the continued development of doubly
curved crystal configurations, such as the “Wittry geometry” for scanning
monochromators, and point-to-point focusing diffractors for producing small
monochromatic X-ray probes to provide improved detection limits for
microanalysis are considered.
Castaing’s Electron Microprobe and Its Impact on Materials
Science
Authors: Newbury Dale E.
Published: June 2020

The development of the electron microprobe by Raymond Castaing provided
a great stimulus to materials science at a critical time in its history. For
the first time, accurate elemental analysis could be performed with a
spatial resolution of 1 µm, well within the dimensions of many
microstructural features. The impact of the microprobe occurred across the
entire spectrum of materials science and engineering. Contributions to the
basic infrastructure of materials science included more accurate and
efficient determination of phase diagrams and diffusion coefficients. The
study of the microstructure of alloys was greatly enhanced by electron
microprobe characterization of major, minor, and trace phases, including
contamination. Finally, the electron microprobe has proven to be a critical
tool for materials engineering, particularly to study failures, which often
begin on a micro-scale and then propagate to the macro-scale with
catastrophic results.
Keynote Address: The Time of Pioneers
Authors: Philibert Jean
Published: June 2020

This article, dedicated to the memory of the late professor Raimond
Castaing, will evoke the birth and the first developments of electron probe
microanalysis in France.
Modification of a Commercial Atomic Force Microscope for Nanorheological Experiments: Adsorbed Polymer Layers
Authors: Notley Shannon M. , Craig Vincent S. J. , Biggs Simon
Published: June 2020

The atomic force microscope (AFM) has previously been applied to the measurement of surface
forces (including adhesion and friction) and to the investigation of material properties, such as hardness. Here
we describe the modification of a commercial AFM that enables the stiffness of interaction between surfaces
to be measured concurrently with the surface forces. The stiffness is described by the rheological phase
difference between the response of the AFM tip to a driving oscillation of the substrate. We present the
interaction between silica surfaces bearing adsorbed polymer, however, the principles could be applied to a wide
variety of materials including biological samples.
Multiple Beam Interference Confocal Microscopy: Tool for Morphological Investigation of a Living Spermatozoon
Authors: Joshi N.V. , Medina H.
Published: June 2020

The interference pattern obtained from a multiple internal reflection of a spermatozoon, sandwiched between the glass plate and the cover plate, was focused on the objective of a scanning confocal microscope. According to optical path differences, morphological details were revealed. The combined features, namely improved resolution in z axis, originating from the interference pattern and the optical sectioning of the confocal scanning system, enhanced the resolution and contrast in an impressive manner. These features permitted unprecedented images of the spermatozoon to be obtained at 0.1 μm optical sectioning and reconstruction of three-dimensional (3-D) images. With the help of optical sectioning, it was possible to estimate the thickness and the morphological details of the spermatozoon.
The Application of Digital Volume Correlation (DVC) to Evaluate Strain Predictions Generated by Finite Element Models of the Osteoarthritic Humeral Head
Authors: Kusins Jonathan , Knowles Nikolas , Columbus Melanie , Oliviero Sara , Dall’Ara Enrico , Athwal George S. , Ferreira Louis M.
Published: June 2020

Continuum-level finite element models (FEMs) of the humerus offer the ability to evaluate joint replacement designs preclinically; however, experimental validation of these models is critical to ensure accuracy. The objective of the current study was to quantify experimental full-field strain magnitudes within osteoarthritic (OA) humeral heads by combining mechanical loading with volumetric microCT imaging and digital volume correlation (DVC). The experimental data was used to evaluate the accuracy of corresponding FEMs. Six OA humeral head osteotomies were harvested from patients being treated with total shoulder arthroplasty and mechanical testing was performed within a microCT scanner. MicroCT images (33.5 µm isotropic voxels) were obtained in a pre- and post-loaded state and BoneDVC was used to quantify full-field experimental strains (≈ 1 mm nodal spacing, accuracy = 351 µstrain, precision = 518 µstrain). Continuum-level FEMs with two types of boundary conditions (BCs) were simulated: DVC-driven and force-driven. Accuracy of the FEMs was found to be sensitive to the BC simulated with better agreement found with the use of DVC-driven BCs (slope = 0.83, r2 = 0.80) compared to force-driven BCs (slope = 0.22, r2 = 0.12). This study quantified mechanical strain distributions within OA trabecular bone and demonstrated the importance of BCs to ensure the accuracy of predictions generated by corresponding FEMs.
Effect of Yttrium Additions in Relation to Oxygen Content on Glass Formation in the Zr50Cu40Al10 Alloy
Authors: Pajor Krzysztof , Kozieł Tomasz , Rutkowski Bogdan , Cios Grzegorz , Błyskun Piotr , Tyrała Dorota , Bała Piotr , Zielińska-Lipiec Anna
Published: June 2020

The effect of yttrium additions on the glass formation of the Zr50Cu40Al10 alloy with high oxygen content was investigated. Unlike other reports showing the positive effect of alloying Zr-based alloys with a few percent of rare earth elements, we examined the Y-to-oxygen ratios. As calculated, a stoichiometric amount of yttrium (2808 at ppm) is required to bind all the oxygen (4212 at ppm) to form the Y2O3. Additionally, the influence of half (1404 at ppm) and double stoichiometric (5616 at ppm) levels of yttrium, with respect to the measured oxygen content to be bound was evaluated. The Y-doped alloys were synthesized by arc melting, followed by suction casting into copper molds with conical and rod cavities. The critical diameter of the undoped alloy was below 3 mm, while stoichiometric and double stoichiometric yttrium concentrations allowed to obtain 5 and 7 mm diameter glassy samples, respectively. Microstructure observations confirmed the scavenging effect of yttrium, leading to the formation of a cubic (

$$ Ia\bar{3} $$

I
a

3

¯

space group) yttrium sesquioxide. The glass forming ability of the alloys was additionally determined based on differential thermal analysis, allowing to propose the best indicator for the studied Zr-Cu-Al alloys.
High resolution strain mapping of a single axially heterostructured nanowire using scanning X-ray diffraction
Authors: Hammarberg Susanna , Dagytė Vilgailė , Chayanun Lert , Hill Megan O. , Wyke Alexander , Björling Alexander , Johansson Ulf , Kalbfleisch Sebastian , Heurlin Magnus , Lauhon Lincoln J. , Borgström Magnus T. , Wallentin Jesper
Published: June 2020

Axially heterostructured nanowires are a promising platform for next generation electronic and optoelectronic devices. Reports based on theoretical modeling have predicted more complex strain distributions and increased critical layer thicknesses than in thin films, due to lateral strain relaxation at the surface, but the understanding of the growth and strain distributions in these complex structures is hampered by the lack of high-resolution characterization techniques. Here, we demonstrate strain mapping of an axially segmented GaInP-InP 190 nm diameter nanowire heterostructure using scanning X-ray diffraction. We systematically investigate the strain distribution and lattice tilt in three different segment lengths from 45 to 170 nm, obtaining strain maps with about 10−4 relative strain sensitivity. The experiments were performed using the 90 nm diameter nanofocus at the NanoMAX beamline, taking advantage of the high coherent flux from the first diffraction limited storage ring MAX IV. The experimental results are in good agreement with a full simulation of the experiment based on a three-dimensional (3D) finite element model. The largest segments show a complex profile, where the lateral strain relaxation at the surface leads to a dome-shaped strain distribution from the mismatched interfaces, and a change from tensile to compressive strain within a single segment. The lattice tilt maps show a cross-shaped profile with excellent qualitative and quantitative agreement with the simulations. In contrast, the shortest measured InP segment is almost fully adapted to the surrounding GaInP segments.
Structure, morphology, and microwave dielectric properties of SmAlO3 synthesized by stearic acid route
Authors: Li Jiamao , Zhang Chuimin , Liu Hui , Qiu Tai , Fan Chuangang
Published: June 2020

A rapid and facile approach was developed for the synthesis of ultrafine SmAlO3 powders through the combustion of stearic acid precursors. The obtained products were characterized by typical techniques including X-ray diffraction (XRD), Fourier Transform Infrared (FT-IR), thermogravimetric and differential thermal analysis (TG-DTA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) to analyze the phase composition and microstructure. The dielectric characteristics of SmAlO3 microwave ceramics, using the as-obtained products as original materials, were also studied. Compared with the conventional solid-state reaction method, the synthesis temperature was dramatically reduced to 750 °C. The large-size sheet structure was composed of a number of micro/nano-scale crystallites, which were mostly irregular in shape due to the mutual growth and overlapping shapes of adjacent grains. The SmAlO3 ceramics with high density and uniform microstructure were obtained after sintering at 1500 °C for 4 h due to the favorable sintering activity of the as-synthesized powders. In addition, desired dielectric properties at microwave frequencies (dielectric constant εr = 20.22, quality factor Q·f = 74110 GHz, and a temperature coefficient of resonant frequency τf = −74.6 ppm/°C) were achieved.
Real-Time Influence Maximization in a RTB Setting
Authors: Dupuis David , du Mouza Cédric , Travers Nicolas , Chareyron Gaël
Published: June 2020

To maximize the impact of an advertisement campaign on social networks, the real-time bidding (RTB) systems aim at targeting the most influential users of this network. Influence maximization (IM) is a solution that addresses this issue by maximizing the coverage of the network with top-k influencers who maximize the diffusion of information. Associated with online advertising strategies at Web scale, RTB is faced with complex ad placement decisions in real time to deal with a high-speed stream of online users. To tackle this issue, IM strategies should be modified in order to integrate RTB constraints. While most traditional IM methods deal with static sets of top influencers, they hardly address the dynamic influence targeting issue by integrating short time decision, no interchange and stream’s incompleteness. This paper proposes a real-time influence maximization approach which takes influence maximization decisions within a real-time bidding environment. A deep analysis of influence scores of users over several social networks is presented as well a strategy to guarantee the impact of an IM strategy in order to define the budget of an ad campaign. Finally, we offer a thorough experimental process to compare static versus dynamic IM solutionswrt. influence scores.
Normalised degree variance
Authors: Smith Keith M. , Escudero Javier
Published: June 2020

Finding graph indices which are unbiased to network size and density is of high importance both within a given field and across fields for enhancing comparability of modern network science studies. The degree variance is an important metric for characterising network degree heterogeneity. Here, we provide an analytically valid normalisation of degree variance to replace previous normalisations which are either invalid or not applicable to all networks. It is shown that this normalisation provides equal values for graphs and their complements; it is maximal in the star graph (and its complement); and its expected value is constant with respect to density for Erdös-Rényi (ER) random graphs of the same size. We strengthen these results with model observations in ER random graphs, random geometric graphs, scale-free networks, random hierarchy networks and resting-state brain networks, showing that the proposed normalisation is generally less affected by both network size and density than previous normalisation attempts. The closed form expression proposed also benefits from high computational efficiency and straightforward mathematical analysis. Analysis of 184 real-world binary networks across different disciplines shows that normalised degree variance is not correlated with average degree and is robust to node and edge subsampling. Comparisons across subdomains of biological networks reveals greater degree heterogeneity among brain connectomes and food webs than in protein interaction networks.