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131.
Sumit Kumar Michele Merelli Wojciech Danowski Petra Rudolf Ben L. Feringa Ryan C. Chiechi 《Advanced materials (Deerfield Beach, Fla.)》2019,31(15)
This paper describes the reversible chemical locking of sypiropyran switches bound to metallic surfaces to enable the encoding of nonvolatile information. Data are encoded spatially by selectively locking the spiropyran moieties in their merocyanine form using a combination of exposure to acid and UV light. Without exposure to acid, the merocyanine form spontaneously converts back to the spiropyran form. Bits are resolved by defining the regions of the monolayer that are exposed to acid, using a “soft punchcard” fabricated from a silicone elastomer. Information is read by measuring the tunneling charge–transport through the monolayer using eutectic Ga–In top‐contacts. The merocyanine form is more than three orders of magnitude more conductive than the spiropyran form, allowing the differentiation of bits. Photoelectron spectroscopy shows that the monolayers are undamaged by exposure to light, acid, base, and applied bias, enabling proof‐of‐concept devices in which an 8‐bit ASCII encoded six‐character string is written, erased, and rewritten. 相似文献
132.
The wide adoption of path‐tracing algorithms in high‐end realistic rendering has stimulated many diverse research initiatives. In this paper we present a coherent survey of methods that utilize Monte Carlo integration for estimating light transport in scenes containing participating media. Our work complements the volume‐rendering state‐of‐the‐art report by Cerezo et al. [ CPP*05 ]; we review publications accumulated since its publication over a decade ago, and include earlier methods that are key for building light transport paths in a stochastic manner. We begin by describing analog and non‐analog procedures for free‐path sampling and discuss various expected‐value, collision, and track‐length estimators for computing transmittance. We then review the various rendering algorithms that employ these as building blocks for path sampling. Special attention is devoted to null‐collision methods that utilize fictitious matter to handle spatially varying densities; we import two “next‐flight” estimators originally developed in nuclear sciences. Whenever possible, we draw connections between image‐synthesis techniques and methods from particle physics and neutron transport to provide the reader with a broader context. 相似文献
133.
Recently researchers have started employing Monte Carlo‐like line sample estimators in rendering, demonstrating dramatic reductions in variance (visible noise) for effects such as soft shadows, defocus blur, and participating media. Unfortunately, there is currently no formal theoretical framework to predict and analyze Monte Carlo variance using line and segment samples which have inherently anisotropic Fourier power spectra. In this work, we propose a theoretical formulation for lines and finite‐length segment samples in the frequency domain that allows analyzing their anisotropic power spectra using previous isotropic variance and convergence tools. Our analysis shows that judiciously oriented line samples not only reduce the dimensionality but also pre‐filter C0 discontinuities, resulting in further improvement in variance and convergence rates. Our theoretical insights also explain how finite‐length segment samples impact variance and convergence rates only by pre‐filtering discontinuities. We further extend our analysis to consider (uncorrelated) multi‐directional line (segment) sampling, showing that such schemes can increase variance compared to unidirectional sampling. We validate our theoretical results with a set of experiments including direct lighting, ambient occlusion, and volumetric caustics using points, lines, and segment samples. 相似文献
134.
Mariusz Mital Kosma Szutkowski Karolina Bossak-Ahmad Piotr Skrobecki Simon C. Drew Jarosaw Poznaski Igor Zhukov Tomasz Frczyk Wojciech Bal 《International journal of molecular sciences》2020,21(23)
The A peptide is a major beta-amyloid species in the human brain, forming toxic aggregates related to Alzheimer’s Disease. It also strongly chelates Cu(II) at the N-terminal Phe-Arg-His ATCUN motif, as demonstrated in A and A model peptides. The resulting complex resists ROS generation and exchange processes and may help protect synapses from copper-related oxidative damage. Structural characterization of Cu(II)A complexes by NMR would help elucidate their biological function, but is precluded by Cu(II) paramagneticism. Instead we used an isostructural diamagnetic Pd(II)-A complex as a model. To avoid a kinetic trapping of Pd(II) in an inappropriate transient structure, we designed an appropriate pH-dependent synthetic procedure for ATCUN Pd(II)A, controlled by CD, fluorescence and ESI-MS. Its assignments and structure at pH 6.5 were obtained by TOCSY, NOESY, ROESY, H-C HSQC and H-N HSQC NMR experiments, for natural abundance C and N isotopes, aided by corresponding experiments for Pd(II)-Phe-Arg-His. The square-planar Pd(II)-ATCUN coordination was confirmed, with the rest of the peptide mostly unstructured. The diffusion rates of A, Pd(II)-A and their mixture determined using PGSE-NMR experiment suggested that the Pd(II) complex forms a supramolecular assembly with the apopeptide. These results confirm that Pd(II) substitution enables NMR studies of structural aspects of Cu(II)-A complexes. 相似文献
135.
Da-Jhan Chiu Ying Li Chi-Kuang Feng Mu-Rong Yang Ko-Shao Chen Wojciech Swieszkowski 《Journal of Polymer Research》2017,24(12):227
Hydroxyapatite (HA) hybridized poly(N-isopropylacrylamide)-co-acrylic acid (PNIPAM-co-AAc) hydrogel on thermoplastic polyurethane (TPU) were successfully prepared via photocatalytic polymerization technique. Low temperature plasma processing of HMDSZ and O2 plasma were deposition on substrate. The HA/hydrogel were stabilized by HA of which the wettability was modified by calcium nitrate and ammonium phosphate dibasic. The HA gradually increases with the increase of time cycles. The deposition of organic silicone group by the HMDSZ on the TPU substrate is hydrophobic surface. When deposition of O2, the water contact angles (WCA) was changed to <10° and surface hydrophilicity. The materials were characterized by OM, SEM, FT-IR, XPS and XRD. The results showed that the NIPAM: AAc (1:1 mol) polymers possess macropores ranging from 2 to 20 μm, and their large numbers of carboxyl groups and hydroxyl groups result in a favorable adsorption capacity for HA. Swelling studies indicated that NIPAM: AAc (1:1 mol) was 446 ± 0.3%. This work provided a promising alternative method for the fabrication of polymer materials with tunable and interconnected pores structures for the HA. 相似文献
136.
Zurek WH Dorner U 《Philosophical transactions. Series A, Mathematical, physical, and engineering sciences》2008,366(1877):2953-2972
We extend the theory of symmetry-breaking dynamics in non-equilibrium second-order phase transitions known as the Kibble-Zurek mechanism (KZM) to transitions where the change of phase occurs not in time but in space. This can be due to a time-independent spatial variation of a field that imposes a phase with one symmetry to the left of where it attains critical value, while allowing spontaneous symmetry breaking to the right of that critical borderline. Topological defects need not form in such a situation. We show, however, that the size, in space, of the 'scar' over which the order parameter adjusts as it 'bends' interpolating between the phases with different symmetries follows from a KZM-like approach. As we illustrate on the example of a transverse quantum Ising model, in quantum phase transitions this spatial scale--the size of the scar--is directly reflected in the energy spectrum of the system: in particular, it determines the size of the energy gap. 相似文献
137.
Zaleszczyk W Janik E Presz A Dłuzewski P Kret S Szuszkiewicz W Morhange JF Dynowska E Kirmse H Neumann W Petroutchik A Baczewski LT Karczewski G Wojtowicz T 《Nano letters》2008,8(11):4061-4065
It is shown that the growth of II-VI diluted magnetic semiconductor nanowires is possible by the catalytically enhanced molecular beam epitaxy (MBE). Zn(1-x)MnxTe NWs with manganese content up to x=0.60 were produced by this method. X-ray diffraction, Raman spectroscopy, and temperature dependent photoluminescence measurements confirm the incorporation of Mn(2+) ions in the cation substitutional sites of the ZnTe matrix of the NWs. 相似文献
138.
Nanoengineered biodegradable constructs based on synthetic and natural polymers enriched with hydroxyapatite (HA) nanoparticles have been found to mimic the extracellular matrix of bone tissue. The main objective of this study was to create biocomposite nanostructured scaffolds by incorporating collagen and HA nanoparticles into poly(L-lactic acid)-co-poly(?-caprolactone) by electrospinning. The fiber diameter of the composite PLCL/Col and PLCL/Col/HA fibers was smaller compared to PLCL. In vitro biocompatibility of the scaffolds studied using human fetal osteoblasts and EDX analysis showed high deposition of calcium on PLCL/Col/HA. The results shows that PLCL/Col/HA nanofibrous constructs have huge potential as substrates for bone regeneration. 相似文献
139.
Chen CW Suchanek WL Shuk P Byrappa K Oakes C Riman RE Brown K Tenhuisen KS Janas VF 《Journal of materials science. Materials in medicine》2007,18(7):1413-1421
The role of citrate washing on the physical and chemical characteristics of magnesium-substituted apatites (HAMgs) was performed.
HAMgs were synthesized by a mechanochemical–hydrothermal route at room temperature in as little as 1 h, which is five times
faster than our previous work. Magnesium-substituted apatites had concentrations as high as 17.6 wt% Mg with a corresponding
specific surface area (SSA) of 216 m2/g. A systematic study was performed to examine the influence of increasing magnesium content on the physical and chemical
characteristics of the reaction products. As the magnesium content increased from 0 to 17.6 wt%, magnesium-doped apatite crystallite
size decreased from 12 to 8.8 nm. The Mg/(Mg + Ca) ratio in the product was enriched relative to that used for the reacting
precursor solution. During mechanochemical–hydrothermal reaction, magnesium doped apatites co-crystallize with magnesium hydroxide.
Citrate washing serves to remove the magnesium hydroxide phase. The concomitant increase in surface area results because of
the removal of this phase. Possible mechanisms for magnesium hydroxide leaching are discussed to explain the measured trends. 相似文献
140.
RAPD with microsatellite as a tool for differentiation of Candida genus yeasts isolated in brewing 总被引:3,自引:0,他引:3
Walczak E Czaplińska A Barszczewski W Wilgosz M Wojtatowicz M Robak M 《Food microbiology》2007,24(3):305-312
Fifteen wild yeast strains were isolated in two factories of a lager brewing company in Poland. Their identification with API 32C system showed mainly the presence of Candida sake species (7/15). To differentiate the isolates, randomly amplified polymorphic DNA (RAPD) with (GTG)(5), (GAC)(5), (GACA)(4) microsatellite primers and M13 core sequence (5'-GAG GGT GGC GGT TCT-3') were chosen. The results of patterns similarity are presented as dendrograms for each RAPD analysis and for overall patterns. On the overall patterns, all isolates identified as C. sake, except Strain No. 1, were regrouped in one cluster. Collection strain C. sake CBS 617 was similar in 46% to the cluster with six isolates (Strain Nos. 3, 6, 8, 11, 13, 14). The second reference strain C. sake CBS 159 and the Strain No. 1 were regrouped with other Candida species (collection strains) showing, respectively, only 20% and 42% of similarity to other C. sake strains. The similarity based on the overall dendrogram between isolate Nos. 3, 6, 8, 11, 13, 14 and C. sake CBS 617 was 49%. Between those strains and other Candida, the similarity was only 37%. 相似文献