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https://www.readbyqxmd.com/read/28214624/effect-of-cobalt-loading-on-the-solid-state-properties-and-ethyl-acetate-oxidation-performance-of-cobalt-cerium-mixed-oxides
#1
M Konsolakis, S A C Carabineiro, G E Marnellos, M F Asad, O S G P Soares, M F R Pereira, J J M Órfão, J L Figueiredo
Cobalt-cerium mixed oxides were prepared by the wet impregnation method and evaluated for volatile organic compounds (VOCs) abatement, using ethyl acetate (EtAc) as model molecule. The impact of Co content on the physicochemical characteristics of catalysts and EtAc conversion was investigated. The materials were characterized by various techniques, including N2 adsorption at -196°C, scanning electron microscopy (SEM), X-ray diffraction (XRD), H2-temperature programmed reduction (H2-TPR) and X-ray photoelectron spectroscopy (XPS) to reveal the structure-activity relationship...
February 10, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28208292/nanoviscosity-measurements-revealing-domain-formation-in-biomimetic-membranes
#2
Imad Younus Hasan, Adam Mechler
Partitioning of lipid molecules in biomimetic membranes is a model system for the study of naturally occurring domains, such as rafts, in biological membranes. The existence of nanometer scale membrane domains in binary lipid mixtures has been shown with microscopy methods; however, the nature of these domains has not been established unequivocally. A common notion is to ascribe domain separation to thermodynamic phase equilibria. However, characterizing thermodynamic phases of single bilayer membranes has not been possible due to their extreme dimensions: the size of the domains falls to the order of tens to hundreds of nanometers whereas the membrane thickness is only a few nanometers...
February 7, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28207240/interfaces-in-heterogeneous-catalysts-advancing-mechanistic-understanding-through-atomic-scale-measurements
#3
Wenpei Gao, Zachary D Hood, Miaofang Chi
Developing novel catalysts with high efficiency and selectivity is critical for enabling future clean energy conversion technologies. Interfaces in catalyst systems have long been considered the most critical factor in controlling catalytic reaction mechanisms. Interfaces include not only the catalyst surface but also interfaces within catalyst particles and those formed by constructing heterogeneous catalysts. The atomic and electronic structures of catalytic surfaces govern the kinetics of binding and release of reactant molecules from surface atoms...
February 16, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28206764/host-guest-chemistry-at-integrated-porous-space-formed-by-molecular-self-assembly-at-liquid-solid-interfaces
#4
Kohei Iritani, Kazukuni Tahara, Steven De Feyter, Yoshito Tobe
Host-guest chemistry in two-dimensional space, that is physisorbed monolayers of a single atom or a single molecular thickness on surfaces, has become a subject of intense current interest because of perspectives for various applications in molecular-scale electronics, selective sensors, and tailored catalysis. Scanning tunneling microscopy, with which we can visualize molecules in actual space, has been used as a powerful tool. For more than a decade, we have been investigating the self-assembly of a series of triangle-shaped molecules with a phenylene-ethynylene macrocycle, called dehydrobenzo[12]annulenes (DBAs), substituted by six flexible alkyl chains, forming hexagonal porous 2D molecular networks via van der Waals interactions between interdigitated alkyl chains at the interface of organic solvent and graphite...
February 16, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28198806/arrays-of-individual-dna-molecules-on-nanopatterned-substrates
#5
Roland Hager, Alma Halilovic, Jonathan R Burns, Friedrich Schäffler, Stefan Howorka
Arrays of individual molecules can combine the advantages of microarrays and single-molecule studies. They miniaturize assays to reduce sample and reagent consumption and increase throughput, and additionally uncover static and dynamic heterogeneity usually masked in molecular ensembles. However, realizing single-DNA arrays must tackle the challenge of capturing structurally highly dynamic strands onto defined substrate positions. Here, we create single-molecule arrays by electrostatically adhering single-stranded DNA of gene-like length onto positively charged carbon nanoislands...
February 13, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28198180/engineering-recombinant-virus-like-nanoparticles-from-plants-for-cellular-delivery
#6
Lou Brillault, Philippe V Jutras, Noor Dashti, Eva C Thuenemann, Garry Morgan, George P Lomonossoff, Michael J Landsberg, Frank Sainsbury
Understanding capsid assembly following recombinant expression of viral structural proteins is critical to the design and modification of virus-like nanoparticles for biomedical and nanotechnology applications. Here, we use plant-based transient expression of the Bluetongue virus (BTV) structural proteins, VP3 and VP7, to obtain high yields of empty and green fluorescent protein (GFP)-encapsidating core-like particles (CLPs) from leaves. Single-particle cryo-electron microscopy of both types of particles revealed considerable differences in CLP structure compared to the crystal structure of infection-derived CLPs; in contrast, the two recombinant CLPs have an identical external structure...
February 15, 2017: ACS Nano
https://www.readbyqxmd.com/read/28196307/molecule-counts-in-localization-microscopy-with-organic-fluorophores
#7
Mike Heilemann, Franziska Fricke, Christos Karathanasis, Gerhard Hummer
Single-molecule localization microscopy (SMLM) can be used to count fluorescently labeled molecules even when they are not individually resolved. We demonstrate SMLM molecule counting for nucleic acids labeled with the organic fluorophore Alexa Fluor 647 and imaged under photoswitching conditions. From the observed distributions of the number of fluorophore blinking events, we extracted the number of fluorophores per spot using a statistical model. We validate the molecule counting method for single Alexa Fluor 647 fluorophores, and for trimers of Alexa Fluor 647 constructed on a DNA origami structure...
February 14, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28195127/a-novel-application-of-non-destructive-readout-technology-to-localisation-microscopy
#8
Samuel F H Barnett, Mary Snape, C Neil Hunter, Miguel A Juárez, Ashley J Cadby
The fitting precision in localisation microscopy is highly dependent on the signal to noise ratio. To increase the quality of the image it is therefore important to increase the signal to noise ratio of the measurements. We present an imaging system for localisation microscopy based on non-destructive readout camera technology that can increase the signal to noise ratio of localisation based microscopy. This approach allows for much higher frame rates through subsampling a traditional camera frame. By matching the effective exposure to both the start time and duration of a single molecule we diminish the effects of read noise and temporal noise...
February 14, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28194956/direct-imaging-of-single-plasmonic-metal-nanoparticles-in-capillary-with-laser-light-sheet-scattering-imaging
#9
Xuan Cao, Jingjing Feng, Qi Pan, Bin Xiong, Yan He, Edward S Yeung
Understanding the heterogeneous distribution of the physical and chemical properties of plasmonic metal nanoparticles is fundamentally important to their basic and applied research. Traditionally, they are obtained either indirectly via bulk spectroscopic measurements plus electron microscopic characterizations, or through single molecule/particle imaging of nanoparticles immobilized on planar substrates. In this study, by using light-sheet scattering microscopy with a supercontinuum white laser, highly sensitive imaging of individual MNPs flowing inside a capillary, driven by either pressure or electric field, was achieved for the first time...
February 13, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28192299/single-molecule-analysis-of-fluorescent-carbon-dots-towards-localization-based-super-resolution-microscopy
#10
Navneet C Verma, Syamantak Khan, Chayan K Nandi
The advancement of high-resolution bioimaging has always been dependent on the discovery of bright and easily available fluorescent probes. Fluorescent carbon nanodots, an interesting class of relatively new nanomaterials, have emerged as a versatile alternative due to their superior optical properties, non-toxicity, cell penetrability and easy routes to synthesis. Although a plethora of reports is available on bioimaging using carbon dots, single-molecule-based super-resolution imaging is rare in the literature...
October 11, 2016: Methods and Applications in Fluorescence
https://www.readbyqxmd.com/read/28191929/stop-frame-filming-and-discovery-of-reactions-at-the-single-molecule-level-by-transmission-electron-microscopy
#11
Thomas W Chamberlain, Johannes Biskupek, Stephen T Skowron, Alexander V Markevich, Simon Kurasch, Oliver Reimer, Kate Walker, Graham A Rance, Xinliang Feng, Klaus Müllen, Andrey Turchanin, Maria A Lebedeva, Alexander Majouga, Valentine Georgievich Nenajdenko, Ute Kaiser, Elena Besley, Andrei N Khlobystov
We report an approach - named chemTEM - to follow chemical transformations at the single-molecule level with the electron beam of a transmission electron microscope (TEM) applied as both a tuneable source of energy and a sub-Angstrom imaging probe. Deposited on graphene, disk-shaped perchlorocoronene molecules are precluded from intermolecular interactions. This allows monomolecular transformations to be studied at the single-molecule level in real time and reveals chlorine elimination and reactive aryne formation as a key initial stage of multi-step reactions initiated by the 80 keV e-beam...
February 13, 2017: ACS Nano
https://www.readbyqxmd.com/read/28191924/control-of-an-unusual-photo-claisen-rearrangement-in-coumarin-caged-tamoxifen-through-an-extended-spacer
#12
Pamela T Wong, Edward W Roberts, Shengzhuang Tang, Jhindan Mukherjee, Jayme Cannon, Alyssa J Nip, Kaitlin Corbin, Matthew F Krummel, Seok Ki Choi
The use of coumarin caged molecules has been well documented in numerous photocaging applications including for the spatiotemporal control of Cre-estrogen receptor (Cre-ERT2) recombinase activity. In this article, we report that 4-hydroxytamoxifen (4OHT) caged with coumarin via a conventional ether linkage led to an unexpected photo-Claisen rearrangement which significantly competed with the release of free 4OHT. The basis for this unwanted reaction appears to be related to the coumarin structure and its radical-based mechanism of uncaging as it did not occur in ortho-nitrobenzyl (ONB) caged 4OHT that was otherwise linked in the same manner...
February 13, 2017: ACS Chemical Biology
https://www.readbyqxmd.com/read/28186771/contact-forces-between-single-metal-oxide-nanoparticles-in-gas-phase-applications-and-processes
#13
Samir Salameh, Monique A van der Veen, Michael Kappl, J Ruud van Ommen
In this work we present a comprehensive experimental study to determine the contact forces between individual metal oxide nanoparticles in the gas-phase using atomic force microscopy. In addition, we determined the amount of physisorbed water for each type of particle surface. By comparing our results with mathematical models of the interaction forces, we could demonstrate that classical continuum models of van der Waals and capillary forces alone cannot sufficiently describe the experimental findings. Rather, the discrete nature of the molecules has to be considered, which leads to ordering at the interface and the occurrence of solvation forces...
February 10, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28181801/optokinetically-encoded-nanoprobe-based-multiplexing-strategy-for-microrna-profiling
#14
Sungi Kim, Jeong-Eun Park, Woosung Hwang, Jinyoung Seo, Young-Kwang Lee, Jae-Ho Hwang, Jwa-Min Nam
Multiplexed real-time analysis on multiple interacting molecules and particles is needed to obtain information on binding patterns between multiple ligands and receptors, specificity of bond formations and interacting pairs in a complex medi-um, often found in chemical and biological systems, and difference in binding affinity and kinetics for different binding pairs in one solution. In particular, multiplexed profiling of microRNA (miRNA) in a reliable, quantitative manner is of great demand for the use of miRNA in cell biology, biosensing and clinical diagnostic applications, and accurate diagnosis of cancers with miRNA is not possible without detecting multiple miRNA sequences in a highly specific manner...
February 9, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28181501/surface-single-molecule-dynamics-controlled-by-entropy-at-low-temperatures
#15
J C Gehrig, M Penedo, M Parschau, J Schwenk, M A Marioni, E W Hudson, H J Hug
Configuration transitions of individual molecules and atoms on surfaces are traditionally described using an Arrhenius equation with energy barrier and pre-exponential factor (attempt rate) parameters. Characteristic parameters can vary even for identical systems, and pre-exponential factors sometimes differ by orders of magnitude. Using low-temperature scanning tunnelling microscopy (STM) to measure an individual dibutyl sulfide molecule on Au(111), we show that the differences arise when the relative position of tip apex and molecule changes by a fraction of the molecule size...
February 9, 2017: Nature Communications
https://www.readbyqxmd.com/read/28180226/facile-fabrication-of-sudan-red-particle-microcapsules-by-a-polymerizable-gemini-surfactant-and-molecular-assembly-mechanisms
#16
Yaqian Wu, Haike Yan, Xuefeng Shi, Jinben Wang
An efficient method was developed to encapsulate water insoluble organic particles of Sudan red III (SR) in aqueous suspensions by using a polymerizable cationic gemini surfactant, 1,3-bis(N,N-dimethyl-N-cetylammonium)-2-(propylacrylate dibromide) (AGC16). The AGC16 coated SR microcapsules (AGC16@SR) were prepared by absorption of AGC16 on the surface of SR, followed by in situ homopolymerization (PAGC16). Several measurements, including transmission and scanning electron microscopy, isothermal titration calorimetry, zeta potential, electron paramagnetic resonance and small angle X-ray scattering, were performed to determine the adsorption amount of AGC16, and the layer structures and the molecular assembly mechanism in the AGC16@SR and PAGC16@SR systems, respectively...
February 9, 2017: Soft Matter
https://www.readbyqxmd.com/read/28170269/nanomechanical-characterization-of-micellar-surfactant-films-via-atomic-force-microscopy-at-a-graphite-surface
#17
Benjamin L Micklavzina, Shengwei Zhang, Hao He, Marjorie L Longo
In this work, we study the mechanical properties of sodium dodecyl sulfate (SDS) and dodecylamine hydrochloride (DAH) micellar films at a graphite surface via atomic force microscopy (AFM). Breakthrough forces for these films were measured using silicon nitride cantilevers and were found to be 1.1 ± 0.1 nN for a 10 mM DAH film and 3.0 ± 0.3 nN for a 10 mM SDS film. For 10 mM SDS films, it was found that the addition of 1.5 mM of NaCl, Na2SO4, or MgCl2 produced a 50-70% increase in the measured breakthrough force...
February 20, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28170245/direct-pathway-to-molecular-photodissociation-on-metal-surfaces-using-visible-light
#18
Emiko Kazuma, Jaehoon Jung, Hiromu Ueba, Michael Trenary, Yousoo Kim
We demonstrate molecular photodissociation on single-crystalline metal substrates, driven by visible-light irradiation. The visible-light-induced photodissociation on metal substrates has long been thought to never occur, either because visible-light energy is much smaller than the optical energy gap between the frontier electronic states of the molecule or because the molecular excited states have short lifetimes due to the strong hybridization between the adsorbate molecular orbitals (MOs) and metal substrate...
February 17, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28170150/double-strand-breaks-in-a-genome-sized-dna-caused-by-ultrasound-high-frequency-pulsing-induces-greater-damage-than-cw-sonication-and-low-frequency-pulsing-causes-less-damage
#19
Takahiro Kenmotsu, Rinko Kubota, Yusuke Yamashita, Yuko Yoshikawa, Kenji Yoshida, Yoshiaki Watanabe, Tadayuki Imanaka, Kenichi Yoshikawa
DNA double-strand breaks (DSBs) caused by ultrasound were evaluated in a quantitative manner through the use of single-molecule observation with fluorescence microscopy. We compared the effect of time-interval, or pulse, sonication to that of continuous wave (CW) sonication at a fixed frequency of 30 kHz. Pulses caused fewer DSBs than CW sonication, under the same total input energy of ultrasound, when the pulse repetition period was above the order of a second(s). In contrast, pulses caused more DSBs than CW sonication for a pulse width shorter than a second(s)...
February 7, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28168258/spectroscopic-and-microscopic-investigations-of-tautomerization-in-porphycenes-condensed-phases-supersonic-jets-and-single-molecule-studies
#20
P Fita, L Grill, A Listkowski, H Piwoński, S Gawinkowski, M Pszona, J Sepioł, E Mengesha, T Kumagai, J Waluk
We describe various experimental approaches that have been used to obtain a detailed understanding of double hydrogen transfer in porphycene, a model system for intramolecular hydrogen bonding and tautomerism. The emerging picture is that of a multidimensional tautomerization coordinate, with several vibrational modes acting as reaction-promoters or inhibitors through anharmonic intermode coupling. Tunnelling processes, coherent in the case of isolated molecules and incoherent in condensed phases, are found to play a major role even at elevated temperatures...
February 7, 2017: Physical Chemistry Chemical Physics: PCCP
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