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Dark field microscopy

Xuan Cao, Gang Lei, Jingjing Feng, Qi Pan, Xiaodong Wen, Yan He
Creating color difference and improving the color resolution in digital imaging is crucial for better application of color analy-sis. Herein, a novel color modulation analysis strategy was developed by using a homemade tunable multiband laser illumi-nation device, in which the portions of R, G, and B components of the illumination light are discretionarily adjustable, and hence the sample color could be visually modulated continuously in the RGB color space. Through this strategy, the color appearance of single gold nanorods (AuNRs) under dark-field microscopy, was migrated from the spectrally insensitive red region to the spectrally sensitive green-yellow-red region...
January 15, 2018: Analytical Chemistry
Matthias D Koch, Alexander Rohrbach
Mechanical manipulation of single cytoskeleton filaments and their monitoring over long times is difficult because of fluorescence bleaching or phototoxic protein degradation. The integration of label-free microscopy techniques, capable of imaging freely diffusing, weak scatterers such as microtubules (MTs) in real-time, and independent of their orientation, with optical trapping and tracking systems, would allow many new applications. Here, we show that rotating-coherent-scattering microscopy (ROCS) in dark-field mode can also provide strong contrast for structures far from the coverslip such as arrangements of isolated MTs and networks...
January 9, 2018: Biophysical Journal
Maximilian Lasserus, Martin Schnedlitz, Daniel Knez, Roman Messner, Alexander Schiffmann, Florian Lackner, Andreas W Hauser, Ferdinand Hofer, Wolfgang E Ernst
Alloying processes in nanometre-sized Ag@Au and Au@Ag core@shell particles with average radii of 2 nm are studied via high resolution Transmission Electron Microscopy (TEM) imaging on in situ heatable carbon substrates. The bimetallic clusters are synthesized in small droplets of superfluid helium under fully inert conditions. After deposition, they are monitored during a heating cycle to 600 K and subsequent cooling. The core-shell structure, a sharply defined feature of the TEM High-Angle Annular Dark-Field images taken at room temperature, begins to blur with increasing temperature and transforms into a fully mixed alloy around 573 K...
January 10, 2018: Nanoscale
David B Litt, Matthew Jones, Mario Hentschel, Ying Wang, Sui Yang, Hyun Dong Ha, Xiang Zhang, A Paul Alivisatos
Metamaterials are architectures that interact with light in novel ways by virtue of symmetry manipulation, and have opened a window into studying unprecedented light-matter interactions. However, they are commonly fabricated via lithographic methods, are usually static structures, and are limited in how they can react to external stimuli. Here we show that by combining lithographic techniques with DNA-based self-assembly methods, we can construct responsive plasmonic metamaterials that exhibit the plasmonic analog of an effect known as electromagnetically induced transparency (EIT), which can dramatically change their spectra upon motion of their constituent parts...
January 5, 2018: Nano Letters
Kemar R Reid, James R McBride, Nathaniel J Freymeyer, Lucas B Thal, Sandra J Rosenthal
Thick-shell (> 5 nm) InP-ZnSe colloidal quantum dots (QDs) grown by a continuous-injection shell growth process are reported. The growth of a thick crystalline shell is attributed to the high temperature of the growth process and the relatively low lattice mismatch between the InP core and ZnSe shell. In addition to a narrow ensemble photoluminescence (PL) line-width (~ 40 nm), ensemble and single particle emission dynamics measurements indicate that blinking and Auger recombination are reduced in these heterostructures...
December 28, 2017: Nano Letters
Suresh Kumar Chakkarapani, Peng Zhang, Seong Ho Kang
A fluorescence-free real-time three-dimensional (3D) super-localization method for the analysis of 3D structure of organelles (e.g., mitochondria-associated endoplasm reticulum [mito-ER] contacts) in live single cells under physiological conditions was developed with dual-wavelength enhanced dark-field microscopy. The method was applied to live single cells under physiological conditions to analyze the complex 3D mito-ER contact region by choosing an optimum nanotag with distinct scattering properties. Combining dual-view with enhanced dark-field microscopy provided concurrent images of different scattering wavelengths of nanotag-labeled mitochondria and ER...
December 22, 2017: Analytical and Bioanalytical Chemistry
Dinesh Kumar, Gaurav Kumar, Veena Agrawal
The present study was carried out to evaluate the larvicidal potential of methanol, hexane, acetone, chloroform, and aqueous bark extracts of Holarrhena antidysenterica (L.) Wall. and silver nanoparticles (AgNPs) synthesized using aqueous bark extract against the third instar larvae of Aedes aegypti L. and Culex quinquefasciatus Say. AgNPs were prepared by adding 10 ml of aqueous bark extract in 90 ml of 1 mM silver nitrate (AgNO3) solution. After 5 min of mixing, a change in color from yellow to dark brown occurred indicating the synthesis of AgNPs...
December 17, 2017: Parasitology Research
Zhongju Ye, Lin Wei, Xuyao Zeng, Rui Weng, Xingbo Shi, Naidong Wang, Langxing Chen, Lehui Xiao
Exploring the diffusion dynamics of viral capsid proteins (VCP) functionalized nanocarrier on living cell membrane could provide plenty of kinetic information for the better understanding of their biological functionality. Gold nanoparticles are excellent core material of nanocarrier because of the good bio-compatibility as well as versatile surface chemistry. However, due to the strong scattering background from subcellular organelles, it is a grand challenge to selectively image individual nanocarrier on living cell membrane...
December 15, 2017: Analytical Chemistry
Shan-Shan Li, Wen-Yi Zhou, Yi-Xiang Li, Min Jiang, Zheng Guo, Jinhuai Liu, Xing-Jiu Huang
Nanocrystals generally suffer from the agglomeration because of the spontaneous reduction of the system surface energy, resulting in blocking the active sites from reacting with target ions and then severely reducing the electrochemical sensitivity. In this article, a highly ordered self-assembled monolayer array is successfully constructed using ~14 nm Co0.6Fe2.4O4 nanocubes uniformly and controllably distributing on the surface of working electrode (glass carbon plate). The large area and high exposure of the surface defects on Co0...
December 13, 2017: Analytical Chemistry
Martin Wiemann, Antje Vennemann, Franziska Blaske, Michael Sperling, Uwe Karst
The distribution of silver (Ag) into remote organs secondary to the application of Ag nanoparticles (Ag-NP) to the lung is still incompletely understood and was investigated in the rat with imaging methods. Dose-finding experiments were carried out with 50 nm- or 200 nm-sized polyvinyl pyrrolidine (PVP)-coated Ag-NP using alveolar macrophages in vitro and female rats, which received Ag-NP via intratracheal instillation. In the main study, we administered 37.5-300 µg per rat lung of the more toxic Ag50-PVP and assessed the broncho-alveolar lavage fluid (BALF) for inflammatory cells, total protein and fibronectin after three and 21 days...
December 12, 2017: Nanomaterials
I Vieira, J Klemm-Toole, E Buchner, D L Williamson, K O Findley, E De Moor
A new approach for non-isothermal tempering analysis utilizing dilatometry is proposed and was carried out on a medium carbon steel with high silicon and additions of Mo and V for secondary hardening. The method includes a second non-isothermal step performed with the same heating rate (2 °C/min) used for the first step in order to create a baseline for analysis. The results were correlated with several other characterization techniques. Mössbauer spectroscopy confirmed the formation of transition carbides by auto-tempering as well as the presence of retained austenite decomposition (stage II) and cementite precipitation (stage III), which demonstrated significant overlap...
December 11, 2017: Scientific Reports
Shrok Allami, Zainab D Abid Ali, Ying Li, Hayder Hamody, Basher Hasan Jawad, Li Liu, Tianshu Li
A ZnO branched-nanowire (BNW) photoanode was doped with N for use in a photoelectrochemical cell (PEC) to generate H2 from water splitting. First, ZnO BNWs were synthesized by chemical bath deposition method. Two experimental methods were used for N-doping: the time-controlled direct-current glow discharge plasma (DCGDP) and the DC magnetron plasma (DCMP) methods, to optimize N-doping of the NW structure. X-ray photoelectron spectroscopy (XPS) provided the N distribution and atomic percentage in the BNWs. The XPS results confirmed that N distribution into ZnO BNWs occurred by N substitution of O sites in the ZnO structure and through well-screened molecular N2...
October 2017: Heliyon
Exequiel Scialfa, Sylvia Grune, Bibiana Brihuega, Pablo Aguirre, Marina Rivero
Ten Leptospira spp. strains were isolated from water samples from Nievas stream, Olavarría, Buenos Aires province (Argentina). The isolates showed the typical motility and morphology of the genus Leptospira under dark field microscopy, developing in liquid EMJH medium after eight days of incubation at 13°C and 30°C. All isolates were negative by the Multiple Locus Variable Number Tandem Repeat Analysis (MLVA). Molecular identification by 16S rRNA gene sequencing identified all isolates as nonpathogenic leptospires...
November 29, 2017: Revista Argentina de Microbiología
Sindhu Kumari, Junyuan Gao, Richard T Mathias, Xiurong Sun, Amizhdini Eswaramoorthy, Nicholas Browne, Nigel Zhang, Kulandaiappan Varadaraj
Purpose: The objective of this study was to understand the molecular and physiologic mechanisms behind the lens cataract differences in Aquaporin 0-knockout-Heterozygous (AQP0-Htz) mice developed in C57 and FVB (lacks beaded filaments [BFs]) strains. Methods: Lens transparency was studied using dark field light microscopy. Water permeability (Pf) was measured in fiber cell membrane vesicles. Western blotting/immunostaining was performed to verify expression of BF proteins and connexins...
December 1, 2017: Investigative Ophthalmology & Visual Science
Xing Wu, Chen Luo, Peng Hao, Tao Sun, Runsheng Wang, Chaolun Wang, Zhigao Hu, Yawei Li, Jian Zhang, Gennadi Bersuker, Litao Sun, Kinleong Pey
The interface between III-V and metal-oxide-semiconductor materials plays a central role in the operation of high-speed electronic devices, such as transistors and light-emitting diodes. The high-speed property gives the light-emitting diodes a high response speed and low dark current, and they are widely used in communications, infrared remote sensing, optical detection, and other fields. The rational design of high-performance devices requires a detailed understanding of the electronic structure at this interface; however, this understanding remains a challenge, given the complex nature of surface interactions and the dynamic relationship between the morphology evolution and electronic structures...
November 27, 2017: Advanced Materials
John Dosch, Elise Hadley, Cal Wiese, Marissa Soderberg, Tori Houwman, Kai Ding, Alexandra Kharazova, John L Collins, Bart van Knippenberg, Carl Gregory, Alexander Kofman
Cancer stem cells resemble normal tissue-specific stem cells in many aspects, such as self-renewal and plasticity. Like their non-malignant counterparts, cancer stem cells are suggested to exhibit a relative quiescence. The established cancer cell lines reportedly harbor slow-proliferating cells that are positive for some cancer stem cells markers. However, the fate of these cells and their progeny remains unknown. We used time-lapse microscopy and the contrast-based segmentation algorithm to identify and monitor actively dividing and non-dividing cells in human osteosarcoma MG-63 cell line...
November 23, 2017: Cell Cycle
Ramachandran Ishwarya, Baskaralingam Vaseeharan, Subramanian Kalyani, Balan Banumathi, Marimuthu Govindarajan, Naiyf S Alharbi, Shine Kadaikunnan, Mohammed N Al-Anbr, Jamal M Khaled, Giovanni Benelli
The bioactivity of semiconductor nanocomplexes has been poorly studied in the field of pesticide science. In this research, the synthesis of zinc nanoparticles was accomplished through new effortless green chemistry process, using the Ulva lactuca seaweed extract as a reducing and capping agent. The production of U. lactuca-fabricated ZnO nanoparticles (Ul-ZnO Nps) was characterized by powder X-ray diffraction (XRD), UV-visible, Fourier transform infrared (FTIR) spectroscopy, selected area electron diffraction (SAED) analysis and transmission electron microscopy (TEM)...
November 7, 2017: Journal of Photochemistry and Photobiology. B, Biology
Meng Li Liu, Hong Yan Zou, Chun Mei Li, Rong Sheng Li, Cheng Zhi Huang
Selenium nanoparticles (SeNPs) with strong green scattering light serving as light scattering nanoprobes for dark-field microscopy imaging are developed for the first time. The SeNPs show good stability, excellent biocompatibility, and high light-producing power, and can precisely and specifically target cancer cells with overexpressed nucleolin (NCL) after modification with aptamers, revealing that the SeNPs can act as a good light scattering nanoprobe for bioimaging and biolabeling.
November 22, 2017: Chemical Communications: Chem Comm
Fozia Shaheen, Muhammad Hammad Aziz, Muhammad Fakhar-E-Alam, Muhammad Atif, Mahvish Fatima, Riaz Ahmad, Atif Hanif, Saqib Anwar, Fatima Zafar, Ghazanfar Abbas, Syed Mansoor Ali, Mukhtar Ahmed
Graphene-based materials have garnered significant attention because of their versatile bioapplications and extraordinary properties. Graphene oxide (GO) is an extremely oxidized form of graphene accompanied by the functional groups of oxygen on its surface. GO is an outstanding platform on which to pacify silver nanoparticles (Ag NPs), which gives rise to the graphene oxide-silver nanoparticle (GO-Ag) nanocomposite. In this experimental study, the toxicity of graphene oxide-silver (GO-Ag) nanocomposites was assessed in an in vitro human breast cancer model to optimize the parameters of photodynamic therapy...
November 21, 2017: Nanomaterials
Lennart Duschek, Andreas Beyer, Jan Oliver Oelerich, Kerstin Volz
Knowledge of the microscopic elemental composition of multinary III/V semiconductor materials is crucial to the development of functionalized opto-electronic devices. Well-proven composition analysis methods, such as high resolution X-ray diffraction (HRXRD), fail to determine the elemental composition when more than three atomic species are involved. In this work we propose a procedure for the composition analysis of multinary III/V semiconductors at atomic resolution using high angle annular dark field (HAADF) scanning transmission electron microscopy (STEM) image simulations...
November 9, 2017: Ultramicroscopy
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