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https://www.readbyqxmd.com/read/28106419/probing-the-nodal-structure-of-landau-level-wave-functions-in-real-space
#1
J R Bindel, J Ulrich, M Liebmann, M Morgenstern
The inversion layer of p-InSb(110) obtained by Cs adsorption of 1.8% of a monolayer is used to probe the Landau level wave functions within smooth potential valleys by scanning tunneling spectroscopy at 14 T. The nodal structure becomes apparent as a double peak structure of each spin polarized first Landau level, while the zeroth Landau level exhibits a single peak per spin level only. The real space data show single rings of the valley-confined drift states for the zeroth Landau level and double rings for the first Landau level...
January 6, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28106047/scale-dependent-diffusion-anisotropy-in-nanoporous-silicon
#2
Daria Kondrashova, Alexander Lauerer, Dirk Mehlhorn, Hervé Jobic, Armin Feldhoff, Matthias Thommes, Dipanjan Chakraborty, Cedric Gommes, Jovana Zecevic, Petra de Jongh, Armin Bunde, Jörg Kärger, Rustem Valiullin
Nanoporous silicon produced by electrochemical etching of highly B-doped p-type silicon wafers can be prepared with tubular pores imbedded in a silicon matrix. Such materials have found many technological applications and provide a useful model system for studying phase transitions under confinement. This paper reports a joint experimental and simulation study of diffusion in such materials, covering displacements from molecular dimensions up to tens of micrometers with carefully selected probe molecules. In addition to mass transfer through the channels, diffusion (at much smaller rates) is also found to occur in directions perpendicular to the channels, thus providing clear evidence of connectivity...
January 20, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28100695/mapping-the-affinity-landscape-of-thrombin-binding-aptamers-on-2-f-ana-dna-chimeric-g-quadruplex-microarrays
#3
Jory Lietard, Hala Abou Assi, Irene Gómez-Pinto, Carlos González, Mark M Somoza, Masad J Damha
In situ fabricated nucleic acids microarrays are versatile and very high-throughput platforms for aptamer optimization and discovery, but the chemical space that can be probed against a given target has largely been confined to DNA, while RNA and non-natural nucleic acid microarrays are still an essentially uncharted territory. 2'-Fluoroarabinonucleic acid (2'F-ANA) is a prime candidate for such use in microarrays. Indeed, 2'F-ANA chemistry is readily amenable to photolithographic microarray synthesis and its potential in high affinity aptamers has been recently discovered...
January 18, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28097479/structural-and-cooperative-length-scales-in-polymer-gels
#4
Baudouin Géraud, Loren Jørgensen, Christophe Ybert, Hélène Delanoë-Ayari, Catherine Barentin
Understanding the relationship between the material structural details, the geometrical confining constraints, the local dynamical events and the global rheological response is at the core of present investigations on complex fluid properties. In the present article, this problem is addressed on a model yield stress fluid made of highly entangled polymer gels of Carbopol which follows at the macroscopic scale the well-known Herschel-Bulkley rheological law. First, performing local rheology measurements up to high shear rates ([Formula: see text] s(-1))and under confinement, we evidence unambiguously the breakdown of bulk rheology associated with cooperative processes under flow...
January 2017: European Physical Journal. E, Soft Matter
https://www.readbyqxmd.com/read/28093299/freeze-concentration-induced-plga-and-polystyrene-nanoparticle-aggregation-imaging-and-rational-design-of-lyoprotection
#5
Lin Niu, Jayanth Panyam
Long-term storage of stable nanoparticulate systems is critical to the utilization of nanotechnology in biomedical applications. Freeze-drying or lyophilization is the most commonly used approach to preparing stable injectable nano formulations. A detailed understanding of the freezing stress on nanoparticles is essential to the successful preservation of original particle attributes and to the development of reliable lyophilization processes. However, visualization of the freezing process and the underlying mechanisms that result in particle aggregation remains challenging...
January 13, 2017: Journal of Controlled Release: Official Journal of the Controlled Release Society
https://www.readbyqxmd.com/read/28091515/protein-crystal-nucleation-in-pores
#6
Christo N Nanev, Emmanuel Saridakis, Naomi E Chayen
The most powerful method for protein structure determination is X-ray crystallography which relies on the availability of high quality crystals. Obtaining protein crystals is a major bottleneck, and inducing their nucleation is of crucial importance in this field. An effective method to form crystals is to introduce nucleation-inducing heterologous materials into the crystallization solution. Porous materials are exceptionally effective at inducing nucleation. It is shown here that a combined diffusion-adsorption effect can increase protein concentration inside pores, which enables crystal nucleation even under conditions where heterogeneous nucleation on flat surfaces is absent...
January 16, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28081223/high-intensity-jump-training-is-tolerated-during-60-days-of-bed-rest-and-is-very-effective-in-preserving-leg-power-and-lean-body-mass-an-overview-of-the-cologne-rsl-study
#7
Andreas Kramer, Jakob Kümmel, Edwin Mulder, Albert Gollhofer, Petra Frings-Meuthen, Markus Gruber
PURPOSE: Space agencies are looking for effective and efficient countermeasures for the degrading effects of weightlessness on the human body. The aim of this study was to assess the effects of a novel jump exercise countermeasure during bed rest on vitals, body mass, body composition, and jump performance. METHODS: 23 male participants (29±6 years, 181±6 cm, 77±7 kg) were confined to a bed rest facility for 90 days: a 15-day ambulatory measurement phase, a 60-day six-degree head-down-tilt bed rest phase (HDT), and a 15-day ambulatory recovery phase...
2017: PloS One
https://www.readbyqxmd.com/read/28072809/optimal-angle-of-contralateral-oblique-view-in-cervical-interlaminar-epidural-injection-depending-on-the-needle-tip-position
#8
Jun Young Park, Myung-Hwan Karm, Doo Hwan Kim, Jae-Young Lee, Hye-Joo Yun, Jeong Hun Suh
BACKGROUND: Chronic neck and upper extremity pain associated with cervical origin is common, and cervical interlaminar epidural steroid injections (CILESIs) are frequently used to manage the symptoms of cervical spinal disorders. However, CILESIs are associated with risks such as dural puncture and cord injury. OBJECTIVES: We aimed to determine the optimal needle tip visualization, in order to minimize CILESIs-induced complications. STUDY DESIGN: Retrospective observational study...
January 2017: Pain Physician
https://www.readbyqxmd.com/read/28068091/investigation-of-transport-properties-of-water-methanol-solution-through-cnt-with-oscillating-electric-field
#9
Honglei Wang, Jin Shi, Guokui Liu, Yongqin Zhang, Jingjing Zhang, Shenmin Li
Molecular dynamics simulations were used to investigate the transport properties of water-methanol solutions getting through the carbon nanotube (CNT) with an oscillating electric field. Eight alternating electric fields with different oscillation periods were used in this work. Under the oscillating electric field, water molecules have the advantage of occupying CNT over methanol molecules. Meanwhile, the space occupancy of water-methanol solution in the CNT increases with the increasing of oscillating period...
January 9, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28067444/irreversible-conversion-of-a-water-ethanol-solution-into-an-organized-two-dimensional-network-of-alternating-supramolecular-units-in-a-hydrophobic-zeolite-under-pressure
#10
Rossella Arletti, Ettore Fois, Lara Gigli, Giovanna Vezzalini, Simona Quartieri, Gloria Tabacchi
Turning disorder into organization is a key issue in science. By making use of X-ray powder diffraction and modeling studies, we show herein that high pressures in combination with the shape and space constraints of the hydrophobic all-silica zeolite ferrierite separate an ethanol-water liquid mixture into ethanol dimer wires and water tetramer squares. The confined supramolecular blocks alternate in a binary two-dimensional (2D) architecture that remains stable upon complete pressure release. These results support the combined use of high pressures and porous networks as a viable strategy for driving the organization of molecules or nano-objects towards complex, pre-defined patterns relevant for the realization of novel functional nanocomposites...
January 9, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28067115/macro-porous-hydrogel-scaffolds-for-3-d-cell-culture-and-tissue-engineering
#11
Changjiang Fan, Dong-An Wang
Hydrogels have been promising candidate scaffolds for cell delivery and tissue engineering due to their tissue-like physical properties and capability for homogeneous cell loading. However, the encapsulated cells are generally entrapped and constrained in the submicron- or nano-sized gel networks, seriously limiting cell growth and tissue formation. Meanwhile, the spatially-confined settlement inhibits attachment and spreading of anchorage dependent cells, leading to their apoptosis. In recent years, macro-porous hydrogels have attracted increasing attention in use as cell delivery vehicles and tissue engineering scaffolds...
January 8, 2017: Tissue Engineering. Part B, Reviews
https://www.readbyqxmd.com/read/28066979/when-proteostasis-goes-bad-protein-aggregation-in-the-cell
#12
REVIEW
Mona Radwan, Rebecca J Wood, Xiaojing Sui, Danny M Hatters
Protein aggregation is a hallmark of the major neurodegenerative diseases including Alzheimer's, Parkinson's, Huntington's and motor neuron and is a symptom of a breakdown in the management of proteome foldedness. Indeed, it is remarkable that under normal conditions cells can keep their proteome in a highly crowded and confined space without uncontrollable aggregation. Proteins pose a particular challenge relative to other classes of biomolecules because upon synthesis they must typically follow a complex folding pathway to reach their functional conformation (native state)...
January 9, 2017: IUBMB Life
https://www.readbyqxmd.com/read/28059404/second-order-nlo-responses-of-two-cavity-inorganic-electrides-lin-b20h26-n-1-2-evolutions-with-increasing-excess-electron-number-and-various-b-b-connection-sites-of-b20h26
#13
Nana Ma, Jinjin Gong, Shujun Li, Jie Zhang, Yongqing Qiu, Guisheng Zhang
Confining excess electrons in a specific space is an effective strategy to design nonlinear optical (NLO) molecules. The complexants with excess electrons are usually organic compounds, but these compounds are thermally unstable and thus hardly meet the processing requirements of NLO materials. To obtain better thermostability and NLO response molecules, in this work, inorganic compounds of B20H26 isomers containing two cavities were proposed. With the two included cavities, B20H26 can be doped by one or two Li atoms to form electrides of Li@B20H26 and Li2@B20H26...
January 18, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28053350/quasi-one-dimensional-density-of-states-in-a-single-quantum-ring
#14
Heedae Kim, Woojin Lee, Seongho Park, Kwangseuk Kyhm, Koochul Je, Robert A Taylor, Gilles Nogues, Le Si Dang, Jin Dong Song
Generally confinement size is considered to determine the dimensionality of nanostructures. While the exciton Bohr radius is used as a criterion to define either weak or strong confinement in optical experiments, the binding energy of confined excitons is difficult to measure experimentally. One alternative is to use the temperature dependence of the radiative recombination time, which has been employed previously in quantum wells and quantum wires. A one-dimensional loop structure is often assumed to model quantum rings, but this approximation ceases to be valid when the rim width becomes comparable to the ring radius...
January 5, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28048952/adherens-junctions-modulate-diffusion-between-epithelial-cells-in-trichoplax-adhaerens
#15
Carolyn L Smith, Thomas S Reese
Trichoplax adhaerens is the sole named member of Placozoa, an ancient metazoan phylum. This coin-shaped animal glides on ventral cilia to find and digest algae on the substrate. It has only six cell types, all but two of which are incorporated into the epithelium that encloses it. The upper epithelium is thin, composed of a pavement of relatively large polygonal disks, each bearing a cilium. The lower epithelium is thick and composed primarily of narrow ciliated cells that power locomotion. Interspersed among these cells are two different secretory cells: one containing large lipophilic granules that, when released, lyse algae under the animal; the other, less abundant, is replete with smaller secretory granules containing neuropeptides...
December 2016: Biological Bulletin
https://www.readbyqxmd.com/read/28047812/su-g-jep2-09-minimal-skin-dose-increase-in-longitudinal-rotating-biplanar-linac-mr-systems-examination-of-radiation-energy-and-flattening-filter-design
#16
B Fallone, A Keyvanloo, B Burke, J St Aubin, D Baillie, K Wachowicz, B Warkentin, S Steciw
PURPOSE: To quantify increase in entrance skin-dose due to magnetic fields of the Alberta longitudinal linac-MR by examining the effect of radiation energy and flattening filter, using Monte Carlo calculations and accurate 3-D models of the magnetic field. METHODS: The 3-D magnetic fields generated by the bi-planar Linac-MR are calculated with FEM using Opera-3D. BEAMnrc simulates the particle phase-space in the presence of the rapidly decaying fringe field of 0...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047113/su-g-tep2-13-patient-specific-reduction-of-range-uncertainties-in-proton-therapy-by-proton-radiography-with-a-multi-layer-ionization-chamber
#17
S Deffet, P Farace, R Righetto, B Macq, F Vander Stappen
PURPOSE: The conversion from Hounsfield units (HU) to stopping powers is a major source of range uncertainty in proton therapy (PT). Our contribution shows how proton radiographs (PR) acquired with a multi-layer ionization chamber in a PT center can be used for accurate patient positioning and subsequently for patient-specific optimization of the conversion from HU to stopping powers. METHODS: A multi-layer ionization chamber was used to measure the integral depth-dose (IDD) of 220 MeV pencil beam spots passing through several anthropomorphic phantoms...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28046556/we-ab-209-09-optimization-of-rotational-arc-station-parameter-optimized-radiation-therapy
#18
P Dong, B Ungun, S Boyd, L Xing
PURPOSE: To develop a fast optimization method for station parameter optimized radiation therapy (SPORT) and show that SPORT is capable of improving VMAT in both plan quality and delivery efficiency. METHODS: The angular space from 0° to 360° was divided into 180 station points (SPs). A candidate aperture was assigned to each of the SPs based on the calculation results using a column generation algorithm. The weights of the apertures were then obtained by optimizing the objective function using a state-of-the-art GPU based Proximal Operator Graph Solver (POGS) within seconds...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28032993/nanoconfined-ionic-liquids
#19
Shiguo Zhang, Jiaheng Zhang, Yan Zhang, Youquan Deng
Ionic liquids (ILs) have been widely investigated as novel solvents, electrolytes, and soft functional materials. Nevertheless, the widespread applications of ILs in most cases have been hampered by their liquid state. The confinement of ILs into nanoporous hosts is a simple but versatile strategy to overcome this problem. Nanoconfined ILs constitute a new class of composites with the intrinsic chemistries of ILs and the original functions of solid matrices. The interplay between these two components, particularly the confinement effect and the interactions between ILs and pore walls, further endows ILs with significantly distinct physicochemical properties in the restricted space compared to the corresponding bulk systems...
December 29, 2016: Chemical Reviews
https://www.readbyqxmd.com/read/28031394/dose-dependent-progression-of-parkinsonism-in-manganese-exposed-welders
#20
Brad A Racette, Susan Searles Nielsen, Susan R Criswell, Lianne Sheppard, Noah Seixas, Mark N Warden, Harvey Checkoway
OBJECTIVE: To determine whether the parkinsonian phenotype prevalent in welders is progressive, and whether progression is related to degree of exposure to manganese (Mn)-containing welding fume. METHODS: This was a trade union-based longitudinal cohort study of 886 American welding-exposed workers with 1,492 examinations by a movement disorders specialist, including 398 workers with 606 follow-up examinations up to 9.9 years after baseline. We performed linear mixed model regression with cumulative Mn exposure as the independent variable and annual change in Unified Parkinson Disease Rating Scale motor subsection part 3 (UPDRS3) as the primary outcome, and subcategories of the UPDRS3 as secondary outcomes...
December 28, 2016: Neurology
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