Staged self-assembly: nanomanufacture of arbitrary shapes with <Emphasis Type="Italic">O</Emphasis>(1) glues

We introduce staged self-assembly of Wang tiles, where tiles can be added dynamically in sequence and where intermediate constructions can be stored for later mixing. This model and its various constraints and performance measures are motivated by a practical nanofabrication scenario through protein-based bioengineering. Staging allows us to break through the traditional lower bounds in tile self-assembly by encoding the shape in the staging algorithm instead of the tiles. All of our results are based on the practical assumption that only a constant number of glues, and thus only a constant number of tiles, can be engineered. Under this assumption, traditional tile self-assembly cannot even manufacture an n × n square; in contrast, we show how staged assembly in theory enables manufacture of arbitrary shapes in a variety of precise formulations of the model.

Structural and magnetic properties of Pr–Ni substituted Ca0.5Ba0.5Fe12O19 hexa-ferrite nanoparticles

Effect of Pr–Ni substitution on structural and magnetic properties of Ca_0.5Ba_0.5−xPr_xNi_yFe_12−yO₁₉ (x=0.00–0.10 and y=0.00–1.00) prepared by the sol–gel auto combustion method were investigated. The XRD analysis confirmed the single phase M-type hexa-ferrite structure. The lattice parameters were found to increase as Pr–Ni content increases, which is attributed to the ionic size of the implicated cations. The Pr–Ni seems to be completely soluble in the lattice. Transmission electron microscopy reveals that the grain size decreases with increase of Pr–Ni substitution. The coercivity and remanent magnetization ranges from 1511 to 1925 (Oe) and 21.4 to 26.5 (emu/g), respectively. The coercivity values of all the samples fall in the range of M-type hexa-ferrites.     

Feasibility of MRI in the diagnosis of acute diverticulitis: initial results

Purpose: The purpose of this study was to evaluate MRI as a diagnostic tool in patients with suspected acute sigmoid diverticulitis. Furthermore, we sought to develop an optimal imaging protocol in these patients.Patients and methods: Eleven patients with suspected acute diverticulitis were included in the study. All patients were imaged in a 1.0 T clinical scanner using a body-array coil. Imaging sequences were single-shot TSE, HASTE-, STIR- and TrueFisp-sequence. All were obtained in the frontal plane. The diagnosis was verified by a single experienced investigator, using ultrasound, and overall clinicopathological outcome.Results: MRI enabled visualization of signs of an acute diverticulitis in all patients. However, the diagnosis of acute diverticulitis was obtained in 10 patients only. The mean imaging time was 17.5 ± 5.5 min. STIR- and TrueFisp-sequences alone displayed all findings, e.g pericolonic exsudation, edema and segmental narrowing, whereas SSTSE and HASTE-sequences showed no additional information. Therefore, it appeared that the imaging protocol could be restricted to STIR- and TrueFisp-sequences.Conclusion: MRI is feasible as a fast, accurate and investigator-independent diagnostic tool in patients with suspected acute diverticulitis. To prove its value in comparison to computed tomography or ultrasound, further studies are needed.     

The effect of glandular tissue on digestion in the sheep

Digestibility and nitrogen balance trials were carried out with sheep to investigate the action of a commercial food additive, desiccated glandular tissue, on the digestion of hay and mixed hay and barley diets. Use of the additive led to small increases in the apparent digestibility of dietary organic constituents including crude fibre, nitrogen and, in some diets, ether extract. In a second series of experiments with rumen-cannulated sheep the effects of the additive on rumen fermentation were examined using a variety of diets. Supplementation of the diet, in most instances, was associated with an increase in rumen pH and in the proportion of butyric acid in the mixture of short-chain fatty acids in the rumen.     

Vanadium Oxide Based Nanostructured Materials: Novel Oxidative Dehydrogenation Catalysts

Novel vanadium oxide based catalyst derived from the open-framework solid, [Co₃V₁₈O₄₂(H₂O)₁₂(XO₄)]·24 H₂O (X = V, S) (1) catalyses oxidative dehydrogenation of propane to propylene. Catalyst activity was evaluated in the temperature range 250–400 °C with varying gas hourly space velocity (GHSV). At 350 °C and GHSV of 9786 h^?1 and at 1.3% propane conversion the selectivity to propylene was 36.8%. The major products obtained were propylene and CO _x (CO₂ and CO). The ratio of the propylene to CO _x depended directly on the catalytic sites present. Thus, as the amount of the catalyst was decreased, the conversion decreased with an increase in the propylene selectivity and a decrease in the selectivity to carbon oxides—CO _x . The catalyst has been characterized by temperature programmed reduction and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS).     

An improved modeling method to determine the model parameters of photovoltaic (PV) modules using differential evolution (DE)

To accurately model the PV module, it is crucial to include the effects of irradiance and temperature when computing the value of the model parameters. Considering the importance of this issue, this paper proposes an improved modeling approach using differential evolution (DE) method. Unlike other PV modeling techniques, this approach enables the computation of model parameters at any irradiance and temperature point using only the information provided by the manufacturer’s data sheet. The key to this improvement is the ability of DE to simultaneously compute all the model parameters at different irradiance and temperature. To validate the accuracy of the proposed model, three PV modules of different types (multi-crystalline, mono-crystalline and thin-film) are tested. The performance of the model is evaluated against the popular single diode model with series resistance R_s. It is found that the proposed model gives superior results for any irradiance and temperature variations. The modeling method is useful for PV simulator developers who require comprehensive and accurate model for the PV module.     

Systematic MIMO OFDM transceiver implementation for MPSoCs: a nucleus based approach

In this paper, we analyze the potential as well as the limitations of multiprocessor system-on-chip (MPSoC) platforms when implementing software defined radio (SDR) applications for wireless communications. Suitable MPSoCs contain a potentially heterogeneous multi-core computing cluster and can be further equipped with application specific accelerators. The physical layer of a MIMO OFDM transceiver, for which the IEEE 802.11n standard serves as reference, is investigated in this work. To maintain portability, the platform independent algorithmic kernels (Nuclei) are identified first. In the following case study, efficient implementations (Flavors) of these Nuclei are implemented on an MPSoC platform. Resultant algorithmic performance (e.g., frame-error-rate) as well as the system performance (e.g., latency and throughput) are discussed.     

An inorganic–organic hybrid material with a novel oxometallic framework: Hydrothermal synthesis and characterization of [Zn3O3(C13H14N2)3]V6O15

A new hybrid material [Zn₃O₃(C₁₃H₁₄N₂)₃]V₆O₁₅ (1) with extended framework structure has been synthesized hydrothermally and characterized by vibrational spectroscopy, thermogravimetry and complete single crystal X-ray diffraction analysis. The compound has a complex three-dimensional covalent framework structure. It exhibits a fully oxidized novel oxometallic framework containing 10-membered {V₄ZnO₅} oxometalate rings and 4,4′-trimethylene dipyridine ligands (C₁₃H₁₄N₂) that connect pairs of crystallographically equivalent zinc atoms. The extended structure of 1 may also be viewed as containing a framework of corner-sharing {VO₄} and {ZnO₂N₂} polyhedra together with 4,4’-trimethylene dipyridine ligands linking zinc centers. The hybrid material is thermally stable up to 323 °C. It contains metal centers and coordination geometry that make it a potentially attractive model compound for investigating the structures of metallo-organic biomolecules by use of solid state NMR spectroscopic techniques. Crystal data for C₃₉H₄₂N₆O₁₈V₆Zn₃: monoclinicic P2₁, a = 10.9894(9) Å, b = 18.1493 (15) Å, c = 13.0903 (11) Å, β = 109.8880(10)°, V = 2455.1(4) Å³, Z = 2, D_calc. = 1.873 Mg/m³.