Evidence for Diffusion-Controlled Hydrocarbon Selectivities in the Fischer�CTropsch Synthesis Over Cobalt Supported on Ordered Mesoporous Silica

A series of four cobalt-based catalysts (two of which promoted with ruthenium) supported on SiO₂ or SBA-15 were prepared and tested in the Fischer?CTropsch synthesis at industrially relevant process conditions (483 K, 20 bar, H₂/CO ratio = 2.1, pellet size: 53?C90 ??m). The catalysts were characterized by N₂-adsorption, X-ray diffraction (XRD), temperature-programmed reduction (TPR), H₂-chemisorption and transmission electron microscopy (TEM). Ru as promoter enhanced the activity but not the selectivity to long-chain hydrocarbons ( $ {\text{S}}_{{{\text{C}}_{ 5+ } }} $ ). The $ {\text{S}}_{{{\text{C}}_{ 5+ } }} $ values of the SBA-supported catalysts were very low, especially at low conversion levels (i.e. low water partial pressure), suggesting that CO diffusion limitation increased the H₂/CO ratio inside the 1-dimensional (1-D) porous network. A superimposition of the selectivity results on the correlations found in our recent study, derived for Co-based catalysts supported on ??-Al₂O₃, ??-Al₂O₃ and TiO₂ free from diffusion limitations, was made. While the SiO₂-supported catalysts with a 3-D porous structure followed the correlations, the SBA-catalysts deviated significantly at low conversions, giving a further indication that the selectivity results of these catalysts were affected by CO diffusion limitations. Hence, it may be concluded that the kinetically significant diffusion distances (i.e. those long enough to cause an intrapore H₂/CO ratio higher than that of the bulk gas phase) are probably much shorter for 1-D porous networks than for conventional 3-D supports. This is explained by a significantly lower effective diffusivity in 1-D porous networks. The potential of using the correlations between non-ASF distributed hydrocarbons and C₅₊, to give insight on the occurrence of diffusion limitations, was confirmed by superimposing data from the literature that were anticipated to be influenced by CO diffusion limitations.     

Multivalent presentation of mannose on hyperbranched polyglycerol and their interaction with concanavalin A lectin

We describe the synthesis of multivalent mannose derivatives by using hyperbranched polyglycerols (hPG) as a scaffold with different linker structures. Grafting of protected mannose (Man) units is achieved by using Cu(I) -catalyzed Huisgen click chemistry with either an anomeric azide or propargyl ether onto complementarily functionalized alkyne or azido polymer surfaces. NMR spectroscopy, dynamic light scattering (DLS), IR spectroscopy, size-exclusion chromatography (SEC), and elemental analysis have been used to characterize the hPG-Man compounds. The surface availability and bioactivity of Man-modified polymers were evaluated by using a competitive surface plasmon resonance (SPR)-based binding assay by interactions of the glycopolymers with concanavalin A (Con A), a lectin that binds mannose containing molecules. The results indicated that the novel glycoarchitectures presented in this work are efficient inhibitors of Con A-mannose recognition and resulted in inhibitor concentrations (mean IC(50)) from the micro- to the nanomolar range, whereas the corresponding monovalent mannoside (methyl-Man) requires millimolar concentrations. The results provide an interesting structure-activity relationship for libraries of materials that differ in the linkage of the sugar moiety presented on a biocompatible polyglycerol scaffold.     

Comparative Study of the Electrical Properties and Characteristics of Thermally Sprayed Alumina and Spinel Coatings

In this study, APS and HVOF processes have been used to prepare alumina (Al₂O₃) and magnesium spinel (MgAl₂O₄) coatings designed for insulating applications. The electrical characteristics, i.e., dielectric strength and electrical resistance (electrical resistivity) were investigated using different methods: dielectric breakdown test, direct current (DC) measurements, and electrochemical impedance spectroscopy (EIS). The electrical resistance was measured at room temperature at different relative humidity (RH) levels (from 6% RH to 95% RH) as well as at 200 °C. The coating microstructure, phase composition, and water vapor sorption were studied. Differences in the electrical insulating properties due to the different coating system characteristics are discussed. Of the coatings and conditions investigated in this study, the HVOF spinel coatings showed superior dielectric breakdown strength and electrical resistance stability at high humidity levels.     

Microscopic differential cell counts in milk for the evaluation of inflammatory reactions in clinically healthy and subclinically infected bovine mammary glands

Somatic cell count (SCC) is generally regarded as an indicator of udder health. A cut-off value of 100×10(3) cells/ml is currently used in Germany to differentiate between normal and abnormal secretion of quarters. In addition to SCC, differential cell counts (DCC) can be applied for a more detailed analysis of the udder health status. The aim of this study was to differentiate somatic cells in foremilk samples of udder quarters classified as normal secreting by SCC <100×10(3) cells/ml. Twenty cows were selected and 72 normal secreting udder quarters were compared with a control group of six diseased quarters (SCC >100×10(3) cells/ml). In two severely diseased quarters of the control group (SCC of 967×10(3) cells/ml and 1824×10(3) cells/ml) Escherichia coli and Staphylococcus aureus were detected. DCC patterns of milk samples (n = 25) with very low SCC values of ≤6·25×10(3)cells/ml revealed high lymphocyte proportions of up to 92%. Milk cell populations in samples (n = 41) with SCC values of (>6·25 to ≤25)×10(3) cells/ml were also dominated by lymphocytes (mean value 47%), whereas DCC patterns of milk from udder quarters (n = 6) with SCC values (>25 to ≤100)×10(3)cells/ml changed. While in samples (n = 3) with SCC values of (27-33)×10(3) cells/ml macrophages were predominant (35-40%), three milk samples with (43-45)×10(3) cells/ml indicated already inflammatory reactions based on the predominance of polymorphonuclear leucocytes (PMN) (54-63%). In milk samples of diseased quarters PMN were categorically found as dominant cell population with proportions of ≥65%. Macrophages were the second predominant cell population in almost all samples tested in relationship to lymphocytes and PMN. To our knowledge, this is the first study evaluating cell populations in low SCC milk in detail. Udder quarters classified as normal secreting by SCC <100×10(3) cells/ml revealed already inflammatory processes based on DCC.     

Combined heat and power in the Swedish district heating sector—impact of green certificates and CO2 trading on new investments

Combined heat and power (CHP) has been identified by the EU administration as an important means of reducing CO₂-emissions and increasing the energy efficiency. In Sweden, only about one third of the demand for district heat (DH) is supplied from CHP. This share could be significantly larger if the profitability of CHP generation increased. The objective of this study was to analyse the extent to which the profitability for investments in new CHP plants in the Swedish DH sector have changed thanks to the recently implemented trading schemes for green certificates (TGCs) and CO₂ emissions (TEPs). The analysis was carried out using a simulation model of the Swedish DH sector in which the profitability of CHP investments for all DH systems, with and without the two trading schemes applied, is compared. In addition, a comparison was made of the changes in CHP generation, CO₂ emissions, and operation costs if investments are made in the CHP plant shown to be most profitable in each system according to the model. The study shows that the profitability of investments in CHP plants increased significantly with the introductions of TGC and TEP schemes. If all DH utilities also undertook their most profitable CHP investments, the results indicate a major increase in power generation which, in turn, would reduce the CO₂ emissions from the European power sector by up to 13 Mton/year, assuming that coal condensing power is displaced.     

Short-term impact of green certificates and CO2 emissions trading in the Swedish district heating sector

Swedish district-heating (DH) systems use a wide range of energy sources and technologies for heat-and-power generation. This provides the DH utilities with major flexibility in changing their fuel and technology mix when the economic conditions for generation change. Two recently introduced policy instruments have changed the DH utilities’ costs for generation considerably; the tradable green-certificate (TGC) scheme introduced in 2003 in Sweden, and the tradable greenhouse-gas emission permit (TEP) scheme introduced in the EU on January 1, 2005. The objective of this study is to analyse how these two trading schemes impact on the operation of the Swedish DH sector in terms of changes in CHP generation, CO₂ emissions, and operating costs. The analysis was carried out by comparing the most cost-effective operation for the DH utilities, with and without, the two trading schemes applied, using a model that handles the Swedish DH-sector system-by-system. It was found that the volume of renewable power generated in CHP plants only increased slightly owing to the TGC scheme. The TGC and the TEP schemes in force together, however, nearly doubled the renewable power-generation. CO₂ emissions from the DH sector may either increase or decrease depending on the combination of TGC and TEP prices. The overall CO₂ emissions from the European power-generation sector would, however, be reduced for all price combinations assuming that increased Swedish CHP generation replaces coal-condensing power (coal-fired plants with power generation only) in other European countries. The trading schemes also lower the operational costs of the DH sector since the cost increase owing to the use of more expensive fuels and the purchase of TEPs is outweighed by the increased revenues from sales of electricity and TGCs.     

Toward clinical proteomics on a next-generation sequencing platform

We report the first next generation sequencing (NGS) application to identify and quantify proteins. Customization of protein specific aptamers enabled direct conversion of serum protein information into NGS read outs. The intrinsic ability of aptamer sequencing to highly multiplex protein detection and quantification, together with the prospect of DNA sequencing further evolving into a commodity technology, could constitute the core of a novel, universal diagnostics paradigm.     

Masking misfit in confirmatory factor analysis by increasing unique variances: A cautionary note on the usefulness of cutoff values of fit indices.

Fit indices are widely used in order to test the model fit for structural equation models. In a highly influential study, Hu and Bentler (1999) showed that certain cutoff values for these indices could be derived, which, over time, has led to the reification of these suggested thresholds as “golden rules” for establishing the fit or other aspects of structural equation models. The current study shows how differences in unique variances influence the value of the global chi-square model test and the most commonly used fit indices: Root-mean-square error of approximation, standardized root-mean-square residual, and the comparative fit index. Using data simulation, the authors illustrate how the value of the chi-square test, the root-mean-square error of approximation, and the standardized root-mean-square residual are decreased when unique variances are increased although model misspecification is present. For a broader understanding of the phenomenon, the authors used different sample sizes, number of observed variables per factor, and types of misspecification. A theoretical explanation is provided, and implications for the application of structural equation modeling are discussed. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Rotationally invariant similarity measures for nonlocal image denoising

Many natural or texture images contain structures that appear several times in the image. One of the denoising filters that successfully take advantage of such repetitive regions is NL means. Unfortunately, the block matching of NL means cannot handle rotation or mirroring. In this paper, we analyse two natural approaches for a rotationally invariant similarity measure that will be used as an alternative to, respectively a modification of the well-known block matching algorithm in nonlocal means denoising. The first approach is based on moment invariants whereas the second one estimates the rotation angle, rotates the block via interpolation and then uses a standard block matching. In contrast to the standard method, the presented algorithms can find similar regions or patches in an image even if they appear in several rotated or mirrored instances. Hence, one can find more suitable regions for the weighted average and yield improved results.     

Formation of Well‐Ordered Heterojunctions in Polymer:PCBM Photovoltaic Devices

The nanoscale morphology in polymer:PCBM based photovoltaic devices is a major contributor to overall device performance. The disordered nature of the phase‐separated structure, in combination with the small length scales involved and the inherent difficulty of reproducing the exact morphologies when spin‐coating and annealing thin blend films, have greatly hampered the development of a detailed understanding of how morphology impacts photo­voltaic device functioning. In this paper we demonstrate a double nano­imprinting process that allows the formation of nanostructured polymer:PCBM heterojunctions of composition and morphology that can be selected independently. We fabricated photovoltaic (PV) devices with extremely high densities (10¹⁴ mm^?2) of interpenetrating nanoscale columnar features (as small as 25 nm; at or below the exciton diffusion length) in the active layer. By comparing device results of different feature sizes and two different polymer:PCBM combinations, we demonstrate how double imprinting can be a powerful tool to systematically study different parameters in polymer photovoltaic devices.