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Confined Spaces

E Werner, G K Cheong, D Gupta, K D Dorfman, B Mehlig
Experiments measuring DNA extension in nanochannels are at odds with even the most basic predictions of current scaling arguments for the conformations of confined semiflexible polymers such as DNA. We show that a theory based on a weakly self-avoiding, one-dimensional "telegraph" process collapses experimental data and simulation results onto a single master curve throughout the experimentally relevant region of parameter space and explains the mechanisms at play.
December 29, 2017: Physical Review Letters
Mickaël Ménand, Matthieu Sollogoub, Bernard Boitrel, Stéphane Le Gac
Access to allosteric enzyme mimics that ideally associate communicating compartments for catalysis and regulation is still challenging. Whereas a sandwich "cavity-catalyst-cavity" approach, developed mainly with cyclodextrins and porphyrins, appears promising, its counterpart with hexaphyrins featuring rich conformation, aromaticity and coordination behavior has not been prospected at all. We thus developed sandwich hybrids made of two cyclodextrins triply-linked on each side of a hexaphyrin. The latter displays switchable oxidation states with interconvertible conformations (28π antiaromatic and 26π aromatic each adopting rectangular and dumbbell forms)...
January 11, 2018: Chemistry: a European Journal
Yu Kou, Lin-Bing Sun
Noble-metal nanoparticles have attracted great attention because of their excellent catalytic activity. However, the activity of noble-metal nanoparticles is severely dependent on the size of the metal nanoparticles. Therefore, regulation of the nanoparticle size is of great importance. Herein we report an efficient strategy for the first time to regulate the size of platinum (Pt) nanoparticles in a typical mesoporous silica SBA-15 by using the confined spaces. The Pt-containing precursor is introduced to the confined spaces between the template and silica walls in as-prepared SBA-15 by grinding...
January 10, 2018: Inorganic Chemistry
Jeremy Cure, Hala Assi, Kévin Cocq, Lorena Marín, Katia Fajerwerg, Pierre Fau, Eric Beche, Yves J Chabal, Alain Esteve, Carole Rossi
The integration of high-purity nano-objects on substrates remains a great challenge for addressing scaling-up issues in nanotechnology. For instance, grafting gold nanoparticles (NPs) on zinc oxide films, a major step process for catalysis or photovoltaic applications, still remains difficult to master. We report a modified photo-deposition (P-D) approach that achieves tight control of the NPs size (7.5 ± 3 nm), shape (spherical), purity, and high areal density (3500 ± 10 NPs/m2) on ZnO films. This deposition method is also compatible with large ZnO surface areas...
January 9, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Wenlong Zhang, Guoying Deng, Bo Li, Xinxin Zhao, Tao Ji, Guosheng Song, Zhiyin Xiao, Qing Cao, Jingbo Xiao, Xiaojuan Huang, Guoqiang Guan, Rujia Zou, Xinwu Lu, Junqing Hu
The applications of inorganic theranostic agents in clinical trials are generally limited to their innate non-biodegradability and potential long-term biotoxicity. To address this problem, herein via a straightforward and tailored space-confined on-substrate route, we obtained rhenium trioxide (ReO3) nanocubes (NCs) that display a good biocompatibility and biosafety. Importantly, their aqueous dispersion has high localized surface plasmon resonance (LSPR) absorbance in near-infrared (NIR) region different from previous report, which possibly associates with the charge transfer and structural distortion in hydrogen rhenium bronze (HxReO3), as well as ReO3's cubic shape...
December 27, 2017: Biomaterials
Mary T Doolin, Kimberly M Stroka
The in vivo microenvironment is critical for providing physico-chemical signaling cues which ultimately regulate human mesenchymal stem cell (hMSC) behavior in clinically-relevant applications. hMSCs experience mechanical confinement of the cell body and nucleus in 3D tissues during homing and in porous tissue engineered scaffolds, yet the effects of this mechanical cue on hMSC migration are not known. Here, we use a microchannel device to systematically examine the effect of confinement on hMSC migration and cytoskeletal organization...
January 6, 2018: Cytoskeleton
Charles Cherqui, Guoliang Li, Jacob A Busche, Steven C Quillin, Jon P Camden, David J Masiello
Facile control of the radiative and nonradiative properties of plasmonic nanostructures is of practical importance to a wide range of applications in the biological, chemical, optical, information, and energy sciences. For example, the ability to easily tune not only the plasmon spectrum but also the degree of coupling to light and/or heat, quality factor, and optical mode volume would aid the performance and function of nanophotonic devices and molecular sensors that rely upon plasmonic elements to confine and manipulate light at nanoscopic dimension...
January 9, 2018: Journal of Physical Chemistry Letters
Costas Nikiforidis, Dimitris Karefyllakis, Stavroula Salakou, J Harry Bitter, Atze Jan Van der Goot
Proteins and phenols coexist in the confined space of plant cells leading to reactions between them which result in new covalently bonded complex molecules. This kind of reactions has been widely observed during storage and processing of plant materials. However, the nature of the new complex molecules and their physico-chemical properties are largely unknown. Therefore we investigated the structural characteristics of covalent bonded complexes between highly pure sunflower protein isolate (SFPI, 94 wt%) and the dominant phenol in the confined space of a sunflower seed cell (chlorogenic acid, CGA)...
January 4, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Michael Duss, Livia Salvati Manni, Laurent Moser, Stephan Handschin, Raffaele Mezzenga, Henning J Jessen, Ehud M Landau
The unique molecular architecture of lipidic cubic phases (LCPs) and their cubosome dispersions comprise a well-defined, curved bilayer that spans the entire 3-D material space, encompassing a network of two periodic, curved and non-intersecting three-dimensional aqueous channels. The ensuing large lipid/water interfacial area renders these biomaterials an interesting matrix for the lateral immobilization of organocatalysts to catalyze organic reactions in confined water. Herein, we report for the first time the design, synthesis, assembly and characterization of catalytically active LCPs and cubosomes, and demonstrate their applicability as self-assembled, biomimetic and recyclable nanoreactor scaffolds...
January 9, 2018: ACS Applied Materials & Interfaces
Xingyue Qian, Junfei Ding, Jianli Zhang, Yue Zhang, Yining Wang, Erjun Kan, Xin Wang, Junwu Zhu
The exploration of highly active catalysts for hydrogen evolution reaction (HER) is beneficial to realize high catalytic activity and enhance kinetics for water splitting. Herein, flower-like molybdenum disulfide/carbon nitride (MoS2/C3N4) nanosheets with thickness of 4.6 nm and enlarged interlayer spacing of 0.64 nm were synthesized via a facile hydrothermal method. As expected, the ultrathin thickness endowed MoS2/C3N4 with abundant active sites, ensuring outstanding catalytic activity and excellent stability for HER in alkaline electrolyte...
January 8, 2018: Nanoscale
Ashley T Tucker, Sean P Leonard, Cory D DuBois, Gregory A Knauf, Ashley L Cunningham, Claus O Wilke, M Stephen Trent, Bryan W Davies
Peptides have great potential to combat antibiotic resistance. While many platforms can screen peptides for their ability to bind to target cells, there are virtually no platforms that directly assess the functionality of peptides. This limitation is exacerbated when identifying antimicrobial peptides because the phenotype, death, selects against itself and has caused a scientific bottleneck that confines research to a few naturally occurring classes of antimicrobial peptides. We have used this seeming dissonance to develop Surface Localized Antimicrobial Display (SLAY), a platform that allows screening of unlimited numbers of peptides of any length, composition, and structure in a single tube for antimicrobial activity...
January 3, 2018: Cell
Xiang Ye, Leland Mayne, Zhong-Yuan Kan, S Walter Englander
We used hydrogen exchange-mass spectrometry (HX MS) and fluorescence to compare the folding of maltose binding protein (MBP) in free solution and in the GroEL/ES cavity. Upon refolding, MBP initially collapses into a dynamic molten globule-like ensemble, then forms an obligatory on-pathway native-like folding intermediate (1.2 seconds) that brings together sequentially remote segments and then folds globally after a long delay (30 seconds). A single valine to glycine mutation imposes a definable folding defect, slows early intermediate formation by 20-fold, and therefore subsequent global folding by approximately twofold...
January 2, 2018: Proceedings of the National Academy of Sciences of the United States of America
Shengnan Gao, Jiang Zhu, Yifu Zhang, Qiushi Wang, Xuyang Jing, Changgong Meng
Calcein-Ca (II), Zn (II) and Al (III) complexes were successfully intercalated into interlayer surfaces of layered silicate magadiite and fluorescence properties of organic metal-chelates in the confined spaces were investigated. Structures, compositions and morphologies of the intercalated magadiites were adequately studied by tests, including X-ray diffraction, energy-dispersive X-ray spectrometer, elemental mapping, X-ray photoelectron spectroscopy, inductively coupled plasma atomic emission spectroscopy, Fourier-transform infrared spectra, ultraviolet-visible spectroscopy, thermo-gravimetric analysis, differential thermal analysis and scanning electron microscopy...
November 2017: Royal Society Open Science
Hao Wang, Weimin Cheng, Biao Sun, Haiming Yu, Hu Jin
To understand the impacts of the axial-to-radial airflow quantity ratio (denoted as R) and the suction distance (denoted as Ds) on air curtain dust control in a fully mechanized coal face, the 3down610 coal face in Jiangzhuang coal mine was numerically simulated in this study. A mathematic model was established to describe the airflow migration and dust diffusion in a coal face, and a scaled physical model was constructed. The comparison between simulation results and field measurements validated the model and the parameter settings...
December 30, 2017: Environmental Science and Pollution Research International
F Hu, Suprem R Das, Y Luan, T-F Chung, Y P Chen, Z Fei
We report a systematic plasmonic study of twisted bilayer graphene (TBLG)-two graphene layers stacked with a twist angle. Through real-space nanoimaging of TBLG single crystals with a wide distribution of twist angles, we find that TBLG supports confined infrared plasmons that are sensitively dependent on the twist angle. At small twist angles, TBLG has a plasmon wavelength comparable to that of single-layer graphene. At larger twist angles, the plasmon wavelength of TBLG increases significantly with apparently lower damping...
December 15, 2017: Physical Review Letters
Patrick Bruns, Brigitte Röder
Exposure to audiovisual stimuli with a consistent spatial misalignment seems to result in a recalibration of unisensory auditory spatial representations. The previous studies have suggested that this so-called ventriloquism aftereffect is confined to the trained region of space, but yielded inconsistent results as to whether or not recalibration generalizes to untrained sound frequencies. Here, we reassessed the spatial and frequency specificity of the ventriloquism aftereffect by testing whether auditory spatial perception can be independently recalibrated for two different sound frequencies and/or at two different spatial locations...
December 28, 2017: Psychological Research
Zhijun Yan, Xiaobin Jiang, Yan Dai, Wu Xiao, Xiangcun Li, Naixu Du, Gaohong He
In this paper, double carbon shell hollow spheres which provide macropores (mC) for ultrasmall Fe3O4 nanoparticle (10-20nm) encapsulation individually were first prepared (Fe3O4@mC). The well-constructed Fe3O4@mC electrode materials offer the feasibility to study volume change, aggregation and pulverization process of the active Fe3O4 nanoparticles for Li-ion storage in a confined space. Fe3O4@mC exhibits excellent electrochemical performances, and delivers a high capacity of 645 mA h g-1 at 2 A g-1 after 1000 cycles...
December 27, 2017: ACS Applied Materials & Interfaces
Tatsuma Matsuda, Kentaro Horiguchi, Yoshinori Higuchi, Toyoyuki Hanazawa, Yoshitaka Okamoto, Yasuo Iwadate
Tension pneumosella (TP) is a rare entity reported as the invagination of the sphenoid sinus mucosa into the skull base after endonasal transsphenoidal surgery. Few studies have reported on TP, and in these studies, invagination is confined to either the intrasellar or suprasellar area. We encountered a case of unexpected prominent TP toward the intracranial space 5 years after endoscopic endonasal transsphenoidal surgery (EETS) for a nonfunctioning pituitary adenoma. In addition, we present a hypothesis of the underlying mechanism by a pressure gradient change between the extracranial and intracranial space in TP formation...
December 27, 2017: Laryngoscope
Hans Gollwitzer, Ingo J Banke, Johannes Schauwecker, Ludger Gerdesmeyer, Christian Suren
Ischiofemoral impingement (IFI) is a rare cause of hip pain defined by a narrowing of the space between the lateral aspect of the os ischium and the lesser trochanter of the femur. Several underlying anatomic, functional and iatrogenic pathologies have been identified for symptomatic IFI in native hip joints and after total hip arthroplasty. Clinical symptoms vary but most commonly consist of pain of the lower buttock and groin including the inner thigh, and a snapping or clunking phenomenon is often reported...
December 2017: Journal of Hip Preservation Surgery
P Avanzini, V Pelliccia, G Lo Russo, G A Orban, G Rizzolatti
Here we show how anatomical and functional data recorded from patients undergoing stereo-EEG can be used to decompose the cortical processing following nerve stimulation in different stages characterized by specific topography and time course. Tibial, median and trigeminal nerves were stimulated in 96 patients, and the increase in gamma power was evaluated over 11878 cortical sites. All three nerve datasets exhibited similar clusters of time courses: phasic, delayed/prolonged and tonic, which differed in topography, temporal organization and degree of spatial overlap...
December 14, 2017: NeuroImage
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