Metal organic frameworks (MOFs) are porous solids that are potential high performance carbon capture materials. We have mined a hypothetical MOF database for structures that have exceptional low-pressure CO2 adsorption properties. We have applied the REPEAT method to generate accurate atomic charges that regenerate the ab initio electrostatic potential. We show that large scale screening at high accuracy is feasible for thousands of structures. We identify promising synthesis targets, like a simple combination of chrysene linker and vanadium inorganic unit, and examine in detail structural features that make better performing MOFs from those that would not be synthesisable. We find that, although screening large numbers of hypothetical structures is necessary to provide experimental targets, there are limitations to the suggestion of using the this database directly for synthesis targets and propose improvements and constraints that should be incorporated into the design of further generations of such a building-block algorithm to reach the accuracy required for high-quality CO2 adsorption simulation.

The paper describes a virtual OLED (Organic Light-Emitting Diode) laboratory designed to introduce young people to one of the most contemporary devices and technologies which is heavily used in many gadgets familiar to every teenager. In order to make learning science and engineering fun, such an introduction is made in an interactive multimedia-rich format. In the context of touch screen displays for mobile phones., tablets and TVs, the fundamental principles underlying the design, application, and production of OLEDs and OLED-based devices are demonstrated and explained. The lab enables students to practice preparing an OLED and operating an active matrix OLED (AMOLED) online in a virtual environment.

The influence of oxygen content on containerless solidification of Zr80Pt20 alloy has been studied by using conical nozzle levitation (CNL) technique. The doping level of oxygen from 41 to 5450 ppm mass oxygen (PMO) affects the undercooling of the liquid Zr80Pt20 alloy. Time-resolved synchrotron x-ray diffraction revealed that the quasicrystalline (QC) phase precipitated as a primary phase during solidification of the Zr80Pt20 alloy. The amount of the QC phase depends on the oxygen content in the alloy. This indicates that the doping level of oxygen in Zr80Pt20 alloy can be related to the metastable phase formation as well as the glass-formation ability.

Asymmetric (10L) XRD peaks have been employed as a measure of epitaxial quality for aluminum nitride (AlN) nucleation layers (NL) deposited on sapphire substrate. Epitaxial AlN films have been deposited on 2-6” sapphire substrate by reactive sputtering. FWHM of AlN (103) and (105) were found to be an excellent indicator of quality of AlN films for GaN growth. AlN films produced nucleation layers with highly reproducible microstructure and GaN film growth. NLs had in-plane and out-of-plane texture as evident by the pole-figure results and selected area diffraction pattern. Based on electron microscopy results, AlN film thickness for complete atomic ordering was estimated to be 6-7 nm and most of the edge dislocations were seen in the first 20 nm of the film. Excellent thickness and texture uniformity were seen on planar and patterned sapphire substrates. A compressive stress of 2.9±0.2 GPa was seen in our BKM films. The maximum screw and edge dislocation densities of films were found to be ∼3 x 108 cm−2 and ∼9 x 109 cm−2 respectively. The root mean square roughnesses of A-polar films were found to be < 0.3 nm.

Bi2Se3 thin films are imaged in the near-field using spectroscopic scattering type near-field optical microscopy (s-SNOM) at mid infrared laser wavelength region (9-11μm). Single phases Bi2Se3 thin film structures were prepared by mechanical exfoliation on silicon wafers. We report size and wavelength dependent near-field interaction contrasts in both optical amplitude and phase. We show that near-field optical imaging allows material specific identification and characterization of Bi2Se3 exfoliated samples including the confirmation of residual tape presence or removal in stacked films. We describe an alternative “shear exfoliation” sample preparation method which reliably deposits Bi2Se3 without the possibility of adhesive contaminants.

A dislocation-density based crystalline plasticity and specialized finite-element formulations were used to study the behavior of energetic crystalline aggregates. The energetic crystalline material studied was RDX (cyclotrimethylene trinitramine) with a polymer binder and different void porosities. The aggregate was subjected to different dynamic pressures, and the analyses indicate that maximum temperature increases, constrained dislocation densities, and plastic strain accumulations occurred around the void peripheries, which affected overall deformation behavior. These regions of extreme temperature rise and thermal decomposition can result in hot spot formation.

Liposome was synthesized by using mixture of dipalmitoylphosphatidylcholine and cholesterol in the ultrapure water or physiological saline. Phase transformation temperature and vibrational mode of dipalmitoylphosphatidylcholine molecule were detected by using transmission Fourier-transform infrared spectroscopy for aqueous solution, which we developed. The liposomes were fixed on an amorphous carbon mesh for ultra-high resolution transmission electron microscopy observation and stained with platinum thymidine blue. As-prepared liposomes reinforced with cholesterol were spherical in shape with size larger than 100 nm in diameter and still stable in the vacuum. Under the strong electron irradiation condition, the solution enclosed in the liposomes became unstable and then collapsed. On the other hand, the liposome synthesized in the physiological saline sometimes contains crystallized salt. As a result, the liposome shows proper strength to hold wet material in itself in a vacuum and can be used for the transmission electron microscopy observation.

Transparent films of platinum nanoparticles on graphene nanohybrids were synthesized in a two-step process. Reduction of homogeneously dispersed Pt precursor and graphene in water and solution coating/annealing afforded thin films with high catalytic performance as counter electrodes in dye-sensitized solar cells (DSSC). The requisite dispersant consisting of poly(oxyethylene)-(POE) segments and cyclic imide functionalities allowed the in-situ reduction of dihydrogen hexachloroplatinate by ethanol and the formation of nanohybrids of graphene-supported Pt nanoparticles at 4.0 nm diameter. Characterizations of polymeric dispersants by Fourier-transform infrared spectroscopy, thermogravimetric analysis, and nanohybrids by transmission electron microscope were performed. After screening various compositions of Pt/graphene, the nanohybrid film at the specific ratio of 5/1 by weight was fabricated into a counter electrode (CE) for DSSC by the solution casting method. The evaluation of cell performance demonstrated the most improved power conversion efficiency of 8.00%. This is significant achievement in comparison with 7.14% for the DSSC with the conventional platinum sputtered CE. Furthermore, the solution casting method allows the preparation of transparent CE films that are suitable for using as rear-illuminated DSSC. The approach was proven to be feasible by measuring the cell efficiency under rear light illumination. The power efficiency up to 7.01%, comparable to 8.00% by a normally front illumination, has been accomplished. In contrast, the rear illumination at merely 2.36% efficiency was obtained for the DSSC with sputtered platinum CE. Analyses of cyclic voltammetry, electrochemical impedance spectra were well correlated to the high efficiency of the performance caused by this nanohybrid film.

We have studied CuLi0.08Mg1.92 and determined that the compound reacts with hydrogen to form CuLi0.08Mg1.92H5 [1]. Additionally, we have proposed the compound as a negative electrode material which is the main purpose of the present study. Moreover, we have observed that the latter compound acts as a catalyst in the formation of MgH2, LiH, TiH2 [2] and hydrogen desorption. In this work, first principles and phonon calculations were performed in order to establish the reactions occurring at the negative electrode of a Li conversion battery in presence of CuLi0.08Mg1.92H5 and (Li) – solid solution of Mg in Li – approximately Li2Mg3. We have calculated the minimum theoretical specific capacity to be 1156 mAh/g (for an anode with 100% of CuLi0.08Mg1.92H5) and the △Eeq = 0.81 V (vs. Li+/Li) at 298 K. Furthermore, we have determined all the reactions occurring in the referred system and its sequence using Inelastic Incoherent Neutron Scattering (IINS) and X-Ray Diffraction (XRD).

The mechanical properties of ZnO nanowires are the “enabling factor” for piezotronic nanogenerators. Examining the size effects entail the determination of both elastic (i.e. the Young’s Modulus, E) and failure strength (e.g. fracture, fatigue, buckling, etc.) properties of ZnO nanostructures for nanogenerators. An investigation directed to both types of effects is presented here for the first time. On one hand the strength size effects are pointed out and discussed in the framework of a generalized Weibull framework that is set forward for ZnO NWs. On the other hand, the implications of the size effects on elasticity properties are discussed and quantified using numerical simulations. The results demonstrate that the stiffening of smaller NWs can adversely affect the performance in a non-negligible manner, suggesting that both mechanical size-effects have to be considered for design purposes.

In this study, the failure mechanisms of graphene under sliding are examined using atomistic simulations. A 6nm diameter diamond tip is slid (at a controlled normal load) over a graphene monolayer that is adhered to a semi-infinite silicon substrate. The impact of tip adhesion on the wear and frictional behavior of graphene is studied by comparing two diamond tips, one of which has been hydrogen-passivated and the other which is bare carbon. By contrasting the passivated and unpassivated tips, the interplay of adhesive and abrasive wear on the graphene membrane can also be compared. The results of this work indicate that chemical bonding between the tip and the graphene greatly exacerbates tearing in the graphene monolayer by plowing ahead of the indenter, causing material build-up and increasing effective contact area.

In this paper, we developed textile-based sensors for measuring vital signs. We fabricated conductive fiber made from organic conjugated polymers without the use of inorganic materials. While the tensile strength of pure poly-3,4-ethylenedioxythiophene/poly-4-styrene sulfonic acid (PEDOT/PSS) fiber was low, it was unsuitable to fabricate textile-based devices. To avoid this drawback, we examined the composite fibers composed of PEDOT/PSS and poly(vinyl alcohol) (PVA) to obtain good mechanical properties as well as a high electronic conductivity. PVA was used as a matrix component to connect colloidal PEDOT/PSS particles within the fibers. We succeeded continuous and uniform spinning from the mixed solution of PEDOT/PSS and PVA through the modified wet spinning process. Tensile strength of the composite fiber increased to twice that consisted only of PEDOT/PSS. In addition, the electric conductivity increased about three times by the combination with PVA. Textiles made of conductive fibers behaved as flexible electrodes for the detection of heartbeat.

We are interested in designing nanostructured biomaterials using nanoscopic building blocks such as functionalized nanotubes and lipid molecules. In our earlier work, we summarized the multiple control parameters which direct the equilibrium morphology of a specific class of nanostructured biomaterials. Individual lipid molecules were composed of a hydrophilic head group and two hydrophobic tails. A bare nanotube encompassed an ABA architecture, with a hydrophobic shaft (B) and two hydrophilic ends (A). We introduced hydrophilic hairs at one end of the tube to enable selective transport through the channel. The dimensions of the nanotube were set to minimize its hydrophobic mismatch with the lipid bilayer. We used a Molecular Dynamics-based mesoscopic simulation technique called Dissipative Particle Dynamics which simultaneously resolves the structure and dynamics of the nanoscopic building blocks and the hybrid aggregate. The amphiphilic lipids and functionalized nanotubes self-assembled into a stable hybrid vesicle or a bicelle in the presence of a hydrophilic solvent. We showed that the morphology of the hybrid structures was directed by factors such as the temperature, the rigidity of the lipid molecules, and the concentration of the nanotubes. Another type of hybrid nanostructured biomaterial could be multi-component lipid bilayers. In this paper, we present approaches to design hybrid nanostructured materials using multiple lipid species with different chemistries and molecular chain stiffness.

The preparation of site-specific atom-probe tomography (APT) samples containing localized features has become possible with the use of focused ion beams (FIBs). This technique was used to achieve the analysis of surface oxides and oxidized grain boundaries in this paper. Transmission electron microscopy (TEM), providing microstructural and chemical characterization of the same features, has also been used, revealing crucial additional information.

The study of grain boundary oxidation in stainless steels and nickel-based alloys is required in order to understand the mechanisms controlling stress corrosion cracking in nuclear reactors. Samples oxidized under simulated pressurized water reactor primary water conditions were used, and FIB lift-out TEM and APT specimens containing the same oxidized grain boundary were prepared and fully characterized. The results from both techniques were found fully consistent and complementary.

Chromium-rich spinel oxides grew at the surface and into the bulk material, along grain boundaries. Nickel was rejected from the oxides and accumulated ahead of the oxidation front. Lithium, which was present in small quantities in the aqueous environment during oxidation, was incorporated in the oxide. All phases were accurately quantified and the effect of different experimental parameters were analysed.

The paper presents the brief information on particular results of experimental studies dealing with the problems of properties of materials based on fibre-cement and fibre-concrete composites, which are being recently developed, tested and verified, to use them in the plated components of load-carrying structures of building constructions. The problems mentioned are solved in the co-operation with the company of the Research Institute of Building Materials Inc. (“VUSTAH a.s.”) at Brno city in the Czech Republic. The attention is paid to two basic types of material: (i) fibre-cement composite used for the slab components intended for vertical or horizontal building or technology structures, such as permanent shuttering of bridges, timber floor structures and slab flooring, the wall cladding of buildings and formwork of components in manufacturing plants of the concrete units; (ii) glass-fibre-concrete composite mainly intended for the building façade claddings, but also for the objects of daily use. The experimental verification has been mainly oriented to the investigation of physical-mechanical properties, like as the tensile-bending strength, as well as the corresponding modulus of elasticity.

As an important method for preparing ordered mesoporous polymer and carbon, organic template directed self-assembly is facing challenges because of the weak non-covalent interactions between the organic templates and the building blocks. Herein we developed a novel synthetic procedure based on a reactive template-induced self-assembly to construct ordered mesoporous framework. The aldehyde end-group of reactive template can react with the building blocks (i.e., resol) to form a stable covalent bond during the self-assembly process. This leads to an enhanced interaction between resol and template and thus achieves the formation of ordered mesostructure.

The growth mechanism of large-size domains in PbTiO3/SrTiO3 heteroepitaxial thin films was examined using annular bright field (ABF) – scanning transmission electron microscopy and geometric phase analysis (GPA). {101} domain walls surrounded 90° domains. The large 90° domain grows by the coalescence of the nano-size domains of less than 5 nm width. A strain map obtained from the GPA of ABF-STEM image showed that 90° domains interacted elastically and attractively with edge dislocations at PbTiO3/SrTiO3 interface through simple shear strain.