Effect of TiO2 support on immobilization of cobalt porphyrin for electrochemical CO2 reduction

Electrochemical reduction of CO2 is a promising strategy to manage the global carbon balance by trans-forming CO2 into chemicals.The efficiency of CO2 electroreduction is largely dependent on the design of hybrid electrode where both support and catalyst govern the performance of the electrolyzer.In this work,TiO2 calcined at different temperatures,was used as a support for immobilization of cobalt tetraphenyl porphyrin (CoTPP) and its effect on CO2 reduction was studied.It is demonstrated that the crystalline phase of TiO2 and doping of TiO2 apparently affecting CO2 electroreduction.It is found that anatase phase exhibits higher activity and selectivity compared to futile due to the enhanced conductivity which in turn enables faster electron transfer between the support and CoTPP.As for dopants,the carbon dop-ing in anatase TiO2 is proven to further enhance its conductivity,consequently resulting in the enhanced performance.This study implies that the rational design of supports is important for the performance of the hybrid electrode towards electrochemical CO2 reduction.     

Modeling thermophoretic effects in solid-state nanopores

Local modulation of temperature has emerged as a new mechanism for regulation of molecular transport through nanopores. Predicting the effect of such modulations on nanopore transport requires simulation protocols capable of reproducing non-uniform temperature gradients observed in experiment. Conventional molecular dynamics (MD) method typically employs a single thermostat for maintaining a uniform distribution of temperature in the entire simulation domain, and, therefore, can not model local temperature variations. In this article, we describe a set of simulation protocols that enable modeling of nanopore systems featuring non-uniform distributions of temperature. First, we describe a method to impose a temperature gradient in all-atom MD simulations based on a boundary-driven non-equilibrium MD protocol. Then, we use this method to study the effect of temperature gradient on the distribution of ions in bulk solution (the thermophoretic effect). We show that DNA nucleotides exhibit differential response to the same temperature gradient. Next, we describe a method to directly compute the effective force of a thermal gradient on a prototypical biomolecule—a fragment of double-stranded DNA. Following that, we demonstrate an all-atom MD protocol for modeling thermophoretic effects in solid-state nanopores. We show that local heating of a nanopore volume can be used to regulate the nanopore ionic current. Finally, we show how continuum calculations can be coupled to a coarse-grained model of DNA to study the effect of local temperature modulation on electrophoretic motion of DNA through plasmonic nanopores. The computational methods described in this article are expected to find applications in rational design of temperature-responsive nanopore systems.     

Synthetic ion channels via self-assembly: a route for embedding porous polyoxometalate nanocapsules in lipid bilayer membranes

Porous polyoxometalate nanocapsules of Keplerate type are known to exhibit the functionality of biological ion channels; however, their use as an artificial ion channel is tempered by the high negative charge of the capsules, which renders their spontaneous incorporation into a lipid bilayer membrane unlikely. In this Letter we report coarse-grained molecular dynamics simulations that demonstrate a route for embedding negatively charged nanocapsules into lipid bilayer membranes via self-assembly. A homogeneous mixture of water, cationic detergent, and phospholipid was observed to spontaneously self-assemble around the nanocapsule into a layered, liposome-like structure, where the nanocapsule was enveloped by a layer of cationic detergent followed by a layer of phospholipid. Fusion of such a layered liposome with a lipid bilayer membrane was observed to embed the nanocapsule into the lipid bilayer. The resulting assembly was found to remain stable even after the surface of the capsule was exposed to electrolyte. In the latter conformation, water was observed to flow into and out of the capsule as Na(+) cations entered, suggesting that a polyoxometalate nanocapsule can form a functional synthetic ion channel in a lipid bilayer membrane.     

Electromodulated reflectance study of self-assembled Ge/Si quantum dots

We perform an electroreflectance spectroscopy of Ge/Si self-assembled quantum dots in the near-infrared and in the mid-infrared spectral range. Up to three optical transitions are observed. The low-energy resonance is proposed to correspond to a band-to-continuum hole transition in the Ge valence band. The other two modulation signals are attributed to the spatially direct transitions between the electrons confined in the L and Δ(4) valleys of the Ge conduction band, and the localized hole states at the Γ point.     

Li collection experiments on T-11M and T-10 in framework of Li closed loop concept

The concept of a steady state tokamak with plasma facing components (PFC) on the basis of liquid lithium circulation demands the decision of three tasks: lithium injection to the plasma, lithium ions collection before their deposition on the vacuum vessel and lithium returning to the injection zone. Main subject of paper is the investigations of Li collection by different types of limiters intersected the scrape-of-layer (SOL) in T-10 and T-11M tokamaks. For finding solution for this problem in T-11M and T-10, experiments have been applied with Li-, C-rail limiters and ring SS R-limiter-collector (T-11M). The efficiency of Li collection by limiters in T-11M and T-10 tokamaks was investigated by post mortem sample–witness analysis and (T-11M) by the use of the mobile graphite probe (limiter) as a recombination target in the stream of lithium ions. The characteristic depth of lithium penetration in the SOL area of T-11M is about 2 cm and 4 cm in SOL of T-10. The quantitative analysis of the sample–witnesses located on T-11M limiters showed that 60 ± 20% of the lithium injected during plasma operating of T-11M had been collected by limiters. It confirms an opportunity of the lithium ions collection by limiters in tokamak SOL.     

Hypersensitivity and Induced Radioresistance in Chinese Hamster Cells Exposed to Radiations with Different LET Values

We study the impact of radiation LET on manifestation of HRS/IRR response in Chinese hamster cells ovary cells exposed to radiations used in radiotherapy. Earlier we have investigated this response to carbon ions (455 MeV/amu) in the pristine Bragg curve plateau and behind the Bragg peak, ⁶⁰Co γ-rays, and 14.5 MeV neutrons. Now we present results of cytogenetic metaphase analysis in plateau-phase CHO-K1 cells irradiated with scanning beam protons (83 MeV) at doses < 1 Gy and additional data for 14.5 MeV neutrons. Dose curves for frequency of total chromosome aberrations (CA, protons), paired fragments (protons, neutrons), aberrant cells (neutrons) had typical HRS/IRR structure: HRS region (up to 0.1 and 0.15 Gy), IRR region (0.1–0.6 Gy and 0.15–0.35 Gy) for protons and neutrons, respectively, and regular dose dependence. Taken together with previous results, the data show that LET increase shifts the HRS upper border (from 0.08–0.1 Gy for γ-rays, protons and plateau carbons to 0.12–0.15 Gy for “tail” carbons and neutrons). The IRR regions shortens (0.52–0.4 γ-rays and protons, 0.25 plateau carbons, 0.2 Gy “tail” carbons and neutrons). CA level of IRR increases by 1.5–2.5 times for carbons as compared to γ-rays and protons. Outside HRS/IRR the yield of CA also enhanced with LET increase. The results obtained for different LET radiations suggest that CHO-K1 cells with G1-like CA manifested the general feature of the HRS/IRR phenomena.     

Honeycomb-supported perovskite catalysts for high-temperature processes

Pechini route [US Patent No. 3,330,697 (1967)] was used for supporting perovskite-like systems on thin-wall corundum honeycomb support to prepare catalysts for high-temperature processes of methane combustion and selective oxidation into syngas. In this preparation, the surface of corundum monoliths walls was shown to be covered by strongly adhering porous perovskite layer formed by rounded crystals. At high temperatures when pore diffusion is expected to affect catalysts performance in fast reactions, this spatial distribution of the active component could be attractive. In the kinetically controlled region of methane oxidation, samples prepared via Pechini route possess activity comparable with that of samples made via support wet impregnation with mixed nitrate solutions, when an active component is uniformly distributed across the wall thickness. Corundum-supported lanthanum manganite and ferrite are the most active in the reaction of methane combustion, while its selective oxidation into syngas effectively proceeds on supported lanthanum cobaltite and nickelates. Corundum-supported perovskites are more thermally stable as compared with those on γ-alumina support.     

Design rules for phase-matched terahertz surface electromagnetic wave generation by optical rectification in a nonlinear planar waveguide

The theory of guided waves in metal-dielectric planar multilayer structures is applied to reduce the loss and maximize optical nonlinearity for efficient terahertz-field generation in a surface electromagnetic wave by femtosecond laser pulses confined in a (chi)((2)) nonlinear planar waveguide. For typical parameters of thin-film polymer waveguides and metal-dielectric interfaces, the optimal size of the (chi)((2)) waveguide core providing the maximum efficiency of terahertz plasmon-field generation is shown to be less than the wavelength of the optical pump field.     

Depth estimation from single monocular images using deep hybrid network

Multimedia Tools and Applications - Depth estimation is a significant task in the robotics vision. In this paper, we address the depth estimation from a single monocular image, which is a...     

Micellar‐Mediated Block Copolymer Ordering Dynamics Revealed by In Situ Grazing Incidence Small‐Angle X‐Ray Scattering during Spin Coating

Spin coating is one of the most versatile methods to generate nanostructured block copolymer (BCP) thin films which are highly desired for many applications such as nanolithography or organic electronics. The self‐assembly pathways through phase separation, both in solvent and in bulk, strongly influence the final BCP structure obtained after spin coating. As a demonstration, the formation of highly ordered in‐plane lamellae is elucidated herein by using in situ grazing incidence small‐angle X‐ray scattering. A key step in this complex fast organization process is the formation of intermediate micellar phases triggered by solvent affinity toward one of the block. Indeed, directional coalescence of a short‐lived intermediate hexagonal structure of cylindrical micelles enables the development of a final highly ordered lamellar structure, predominantly oriented parallel to the substrate surface. These results suggest that the existence of such transient micellar phases is a crucial process in order to produce highly ordered structures with a specific orientation directly after the BCP thin film deposition; and should be the focus of further optimization for the directed self‐assembly and, more generally, in the bottom‐up nanostructure fabrication.