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Dark field microscopy

Daniele Pullini, Mauro Francesco Sgroi, Agnes Nora Mahmoud, Nicolas Gauquelin, Lorenzo Maschio, Anna Maria Ferrari, Rik Groenen, Cas Damen, Guus Rijnders, Karel H W van den Bos, Sandra Van Aert, Johan Verbeeck
Heterostructures formed by La0.7Sr0.3MnO3/ZnO (LSMO/ZnO) interfaces exhibit extremely interesting electronic properties making them promising candidatea for novel oxide p-n junctions with multifunctional features. In this work, the structure of the interface is studied through a combined experimental/theoretical approach, . Hetero-structures were grown epitaxially and homogeneously on 4" silicon wafers, characterized by advanced electron microscopy imaging and spectroscopy, and simulated by ab-initio DFT calculations...
May 25, 2017: ACS Applied Materials & Interfaces
Monika Tomczyk, Daniel G Stroppa, Ian M Reaney, Paula M Vilarinho
BiFeO3 (BFO) thin films were grown by chemical solution deposition on a range of electrodes to determine their role in controlling the phase formation and microstructure of the films. The crystallization on oxide electrodes followed the sequence: amorphous → Bi2O2(CO3) → perovskite, while those on Pt crystallized directly from the amorphous phase. IrO2 electrodes promoted perovskite phase formation at the lowest temperature and LaNiO3 additionally induced local epitaxial growth. All compositions exhibited fully coherent Fe-rich precipitates within the grain interior of the perovskite matrix, whereas the incoherent Bi2Fe4O9 second phase was also observed at the grain boundaries of BFO grown on Pt electrodes...
May 24, 2017: Physical Chemistry Chemical Physics: PCCP
Xu Wang, Lin-Ying Du, Meng Du, Chao Ma, Jie Zeng, Chun-Jiang Jia, Rui Si
A low-concentration cobalt (∼6 at%) and manganese (∼3 at%) bimetallic oxide catalyst supported on ceria nanorods (CoMnOx/CeO2), as well as its related single metal oxide counterparts (CoOx/CeO2 and MnOx/CeO2) was synthesized via a deposition-precipitation approach. The fresh samples after air-calcination at 400 °C were tested under the reaction conditions of CO oxidation, and showed the following order of reactivity: CoMnOx/CeO2 > CoOx/CeO2 > MnOx/CeO2. X-ray diffraction (XRD) and transmission electron microscopy (TEM) data identified that the structure of the CeO2 support was maintained during deposition of metal (Co, Mn) ions while the corresponding vis-Raman spectra verified that more oxygen vacancies were created after deposition-precipitation than those in pure ceria nanorods...
May 24, 2017: Physical Chemistry Chemical Physics: PCCP
A I Grudyanov, O N Tkacheva, A T Khatagov
The study included 55 patients (24 men and 31 women aged 30-70 years) with chronic periodontal disease and atherosclerosis of brachiocephalic arteries (BCA). Patients in group 1 received only conservative treatment for periodontal disease, while in group 2 both conservative and surgical treatment were performed. The values were evaluated at baseline and 6 months after treatment. Capillaroscopy and laser Doppler flowmetry showed an improvement in periodontal regional vascular network. The level of IL-6 decreased by 3...
2017: Stomatologii︠a︡
Y Daiko, J Schmidt, G Kawamura, S Romeis, D Segets, Y Iwamoto, W Peukert
Surface defects of ZnO nanoparticles were induced via mechanical stressing using a Turbula shaker mixer and a planetary ball mill, and the possibilities for surface modification and functionalization of the ZnO nanoparticles were exemplified by sulfur doping of activated ZnO. Raman spectroscopy reveals that the formation of oxygen vacancies (VO) does not only occur under high stressing conditions in a planetary ball mill but even upon rather 'mild stressing' in the shaker mixer. The temporal evolution of the vacancy concentration in ZnO stressed under different conditions can be described by a model that accounts for stress number and vacancy diffusion with diffusion coefficients of VO of 3...
May 17, 2017: Physical Chemistry Chemical Physics: PCCP
Ira V Rozhdestvenskaya, Enrico Mugnaioli, Marco Schowalter, Martin U Schmidt, Michael Czank, Wulf Depmeier, Andreas Rosenauer
Denisovite is a rare mineral occurring as aggregates of fibres typically 200-500 nm diameter. It was confirmed as a new mineral in 1984, but important facts about its chemical formula, lattice parameters, symmetry and structure have remained incompletely known since then. Recently obtained results from studies using microprobe analysis, X-ray powder diffraction (XRPD), electron crystallography, modelling and Rietveld refinement will be reported. The electron crystallography methods include transmission electron microscopy (TEM), selected-area electron diffraction (SAED), high-angle annular dark-field imaging (HAADF), high-resolution transmission electron microscopy (HRTEM), precession electron diffraction (PED) and electron diffraction tomography (EDT)...
May 1, 2017: IUCrJ
Joep L Peters, Karel H W van den Bos, Sandra Van Aert, Bart Goris, Sara Bals, Daniël Vanmaekelbergh
We present a study of the relation between the surface chemistry and nanocrystal shape of PbSe nanocrystals with a variable Pb-to-Se stoichiometry and density of oleate ligands. The oleate ligand density and binding configuration are monitored by nuclear magnetic resonance and Fourier transform infrared absorbance spectroscopy, allowing us to quantify the number of surface-attached ligands per NC and the nature of the surface-Pb-oleate configuration. The three-dimensional shape of the PbSe nanocrystals is obtained from high-angle annular dark field scanning transmission electron microscopy combined with an atom counting method...
May 9, 2017: Chemistry of Materials: a Publication of the American Chemical Society
Han Wu, Yu-Qi Zhang, Min-Biao Hu, Li-Jun Ren, Yue Lin, Wei Wang
Clusters are an important class of nanoscale molecules or superatoms that exhibit an amazing diversity in structure, chemical composition, shape, and functionality. Assembling two types of clusters is creating emerging cluster-assembled materials (CAMs). In this paper, we report an effective approach to produce quasi two-dimensional (2D) CAMs of two types of spherelike clusters, polyhedral oligomeric silsesquioxanes (POSS), and polyoxometalates (POM). To avoid macrophase separation between the two clusters, they are covalently linked to form a POM-POSS cocluster with Janus characteristics and a dumbbell shape...
May 15, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Adam W Wood, Weixin Chen, Honghyuk Kim, Yingxin Guan, K Forghani, A Anand, T F Kuech, L J Mawst, S E Babcock
The effects of a 45 min anneal at 800 °C on the physical properties and microstructure of a five-period GaAs1-x Bi x /GaAs1-y Bi y superlattice with y ≠ x were studied using room-temperature photoluminesence spectroscopy, high-resolution x-ray diffraction, high-angle annular-dark-field scanning transmission electron microscopy (HAADF-STEM), and atom probe tomography (APT). The anneal resulted in a substantial increase of the photoluminesence intensity over that observed in the as-deposited sample, indicating annihilation of non-radiative recombination centers and stability of the superlattice structure during the anneal...
May 26, 2017: Nanotechnology
Jian-Hua Chen, Xin Zheng, Xiu-Qin Liu
BACKGROUND: Diagnosis of syphilis is difficult. Follow-up and therapy evaluation of syphilitic patients are poor. Little is known about positron emission tomography (PET) in syphilis. This review was to systematically review usefulness of PET for diagnosis, disease extent evaluation, follow-up, and treatment response assessment in patients with syphilis. METHODS: We searched PubMed, EMBASE, SCOPUS, Cochrane Library, Web of Science,, and three Chinese databases (SinoMed, Wanfang, and CNKI) for English and Chinese language articles from inception to September 2016...
May 5, 2017: Chinese Medical Journal
Lei Shao, Zhifang Wang, Feifei Wang, Jiaru Huang, Xiaoping Zhu
OBJECTIVE: To investigate the structural response of diaphragm and soleus of the rat after mechanical ventilation (MV), and to explore the specific mechanism of the dysfunction of both muscles. METHODS: Sixteen male Sprague-Dawley (SD) rats were randomly divided into control group and MV group, with 8 rats in each group. Rats in MV group were treated with controlled ventilation and maintained anesthesia, and those in control group were only anesthetized without MV and maintained anesthesia...
January 2017: Zhonghua Wei Zhong Bing Ji Jiu Yi Xue
Lewys Jones, Sigurd Wenner, Magnus Nord, Per Harald Ninive, Ole Martin Løvvik, Randi Holmestad, Peter D Nellist
Annular dark-field scanning transmission electron microscopy is a powerful tool to study crystal defects at the atomic scale but historically single slow-scanned frames have been plagued by low-frequency scanning-distortions prohibiting accurate strain mapping at atomic resolution. Recently, multi-frame acquisition approaches combined with post-processing have demonstrated significant improvements in strain precision, but the optimum number of frames to record has not been explored. Here we use a non-rigid image registration procedure before applying established strain mapping methods...
April 15, 2017: Ultramicroscopy
Patrícia Diogo, Chantal Fernandes, Francisco Caramelo, Marta Mota, Isabel M Miranda, M A F Faustino, M G P M S Neves, Marciana P Uliana, Kleber T de Oliveira, João M Santos, Teresa Gonçalves
Endodontic biofilms eradication from the infected root canal system remains as the primary focus in endodontic field. In this study, it was assessed the efficacy of antimicrobial Photodynamic Therapy (aPDT) with the Zn(II)chlorin e6 methyl ester (Zn(II)e6Me) activated by red light against monospecies and mixed biofilms of Enterococcus faecalis and Candida albicans. The results were compared with the ones obtained with Rose Bengal (RB), Toluidine Blue-O (TBO), the synthetic tetracationic porphyrin (TMPyP) as well as classical endodontic irrigants (3% NaOCl, 17% EDTA and 2% CHX)...
2017: Frontiers in Microbiology
Jon Ustarroz, Bart Geboes, Hans Vanrompay, Kadir Sentosun, Sara Bals, Tom Breugelmans, Annick Hubin
Nanoporous Pt nanoparticles (NPs) are promising fuel cell catalysts due to their large surface area and increased electrocatalytic activity toward the oxygen reduction reaction (ORR). Herein, we report on the influence of the growth mechanisms on the surface properties of electrodeposited Pt dendritic NPs with large surface areas. The electrochemically active surface was studied by hydrogen underpotential deposition (H UPD) and compared for the first time to high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) quantitative 3D electron tomography of individual nanoparticles...
May 3, 2017: ACS Applied Materials & Interfaces
Anthony D Fouad, Shelly Teng, Shelley H Pu, Julian R Mark, Moyu Fu, Kevin Zhang, Jonathan Huang, David M Raizen, Christopher Fang-Yen
The roundworm Caenorhabditis elegans is widely used as a model for studying conserved pathways for fat storage, aging, and metabolism. The most broadly used methods for imaging fat in C. elegans require fixing and staining the animal. Here, we show that dark field images acquired through an ordinary light microscope can be used to estimate fat levels in worms. We define a metric based on the amount of light scattered per area, and show that this light scattering metric is strongly correlated with worm fat levels as measured by Oil Red O staining across a wide variety of genetic backgrounds and feeding conditions...
April 12, 2017: G3: Genes—Genomes—Genetics
A Gama, E M Carrillo-Casas, R Hernández-Castro, V A Vázquez-Aceituno, S Toussaint-Caire, J Xicohtencatl-Cortes, R Fernández-Martínez, G Moreno-Coutiño
Syphilis is a systemic and sexually transmitted infection caused by Treponema pallidum ssp. pallidum. This spirochete causes different clinical and subclinical stages depending on the duration of infection and immune status of the host. Several tests have been developed for diagnosis, and are classified into direct and indirect methods. The first one includes dark field microscopy, direct fluorescent antibody test in fluids or tissue, and molecular biology techniques. In the indirect method (serologic), the routine tests are used, and are divided in two categories: non-treponemal and treponemal ones...
January 1, 2017: International Journal of STD & AIDS
Mykhailo Barchuk, Mykhaylo Motylenko, Gleb Lukin, Olf Pätzold, David Rafaja
The microstructure of polar GaN layers, grown by upgraded high-temperature vapour phase epitaxy on [001]-oriented sapphire substrates, was studied by means of high-resolution X-ray diffraction and transmission electron microscopy. Systematic differences between reciprocal-space maps measured by X-ray diffraction and those which were simulated for different densities of threading dislocations revealed that threading dislocations are not the only microstructure defect in these GaN layers. Conventional dark-field transmission electron microscopy and convergent-beam electron diffraction detected vertical inversion domains as an additional microstructure feature...
April 1, 2017: Journal of Applied Crystallography
Han Yu, Quan Sun, Jinghuan Yang, Kosei Ueno, Tomoya Oshikiri, Atsushi Kubo, Yasutaka Matsuo, Qihuang Gong, Hiroaki Misawa
We investigated the grating effect in complex gold dolmen structures, in which multiple plasmon modes are present due to plasmon hybridization, experimentally from both the far field and the near field. In particular, the near-field properties were investigated using photoemission electron microscopy, and it was demonstrated that two hybridized plasmon modes on the dolmen structures could be influenced by the grating effect. For comparison, we also investigated the grating effect in arrays of simple nanoblocks and heptamer structures, which were supposed to support a strong bright plasmon mode and a strong dark plasmon mode, respectively, in the near field...
March 20, 2017: Optics Express
C Coll, E Barrigón, L López-Conesa, J Rebled, L Barrutia, I Rey-Stolle, S Estradé, C Algora, F Peiró
We report on the effect of Sb on the microstructure of GaInP layers grown by metal organic vapor phase epitaxy (MOVPE). These layers exhibit a CuPtB single variant ordering due to the intentional misorientation of the substrate (Ge(001) substrates with 6° misorientation towards the nearest [111] axis). The use of Sb as a surfactant during the GaInP growth does not modify the type of ordering, but it is found that the order parameter (η) decreases with increasing Sb flux. Dark field microscopy reveals a variation of the angle of the antiphase boundaries (APBs) with Sb amount...
April 12, 2017: Physical Chemistry Chemical Physics: PCCP
Giuseppe Antonacci
Brillouin microscopy is a non-contact and label-free technique for mapping fundamental micro-mechanical properties in the volume of biological systems. Specular reflections and elastic scattering easily overwhelm the weak Brillouin spectra due to the limited extinction of virtually imaged phased array spectrometers, thereby affecting the image acquisition. In this Letter, a dark-field method was demonstrated to reject the elastic background light using an annular illumination and a confocal detection. To validate the method, images of polystyrene and liquid samples were obtained using both a confocal and the dark-field system...
April 1, 2017: Optics Letters
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