SU-57 – An aluminosilicogermanate with a DFT topology and variable composition

An aluminosilicogermanate with a DFT zeotype framework (denoted as SU-57) was synthesized for the first time by ethanol-assisted hydrothermal synthesis at 160 and 170 °C. The compound was characterized by single crystal and powder X-ray diffraction, scanning and transmission electron microscopy, energy dispersive spectroscopy (EDS), thermogravimetry (TG) and solid state nuclear magnetic resonance (NMR) spectroscopy. SU-57 crystallizes in space group P4₂/n with estimated a ≈ 10.38–10.46 Å, c ≈ 8.88–8.91 Å, V ≈ 957–975 Å³. It has variable Al–Si–Ge composition with an approximate formula |C₂H₁₀N₂| [Al(Si_xGe_1?x)O₄]₂ (x ≈ 0.3–0.9), which results in a super-structure originated from different cation occupancies of the two unique tetrahedral (T) sites. Single crystal X-ray structure refinements, together with results from X-ray powder diffraction (XRPD) and EDS analysis, showed that (i) the AlO₄ and (Si, Ge)O₄ tetrahedra are only partially ordered over the DFT framework and do not follow a strict alternating manner. (ii) Al resides predominantly on one T site and Si and Ge predominantly on the other. (iii) The Al cation concentration (Al/(Al + Si + Ge)) is nearly constant and slightly less than 50 at%, while the Si and Ge cation concentrations vary over a large range. (iv) Al and Ge occupy both T sites. The cation disorder was confirmed by ²⁷Al and ²⁹Si solid state NMR. TG analysis and in situ XRPD showed that SU-57 was stable up to 375 °C in N₂ atmosphere.     

Discovery of Ligands for the Human Intestinal Di‐/Tripeptide Transporter (hPEPT1) Using a QSAR‐Assisted Virtual Screening Strategy

The discovery of novel ligands for the hPEPT1 transporter is reported. By exploiting a fast and rigorously validated QSAR model in combination with the distance in activity‐centered chemical space (DACCS) approach, a database of commercially available compounds (Sigma–Aldrich) was screened for virtual hits. Twelve compounds were then purchased and characterized in an apical [¹⁴C]Gly‐Sar uptake competition assay. Four compounds displayed affinity in the medium‐to‐high range. A simple benzophenone derivative displayed high affinity with a sub‐millimolar binding constant (K_i=0.24 mM ). The results of this study will serve as starting points for future projects, including the design and synthesis of compound libraries that seek to systematically explore the fundamental requirements for binding and transport by hPEPT1.     

Comparison of tenocytes and mesenchymal stem cells seeded on biodegradable scaffolds in a full-size tendon defect model

In order to investigate cell-based tendon regeneration, a tendon rupture was simulated by utilizing a critical full-size model in female rat achilles tendons. For bridging the defect, polyglycol acid (PGA) and collagen type I scaffolds were used and fixed with a frame suture to ensure postoperatively a functional continuity. Scaffolds were seeded with mesenchymal stem cells (MSC) or tenocytes derived from male animals, while control groups were left without cells. After a healing period of 16 weeks, biomechanical, PCR, histologic, and electron microscopic analyses of the regenerates were performed. Genomic PCR for male-specific gene was used to detect transplanted cells in the regenerates. After 16 weeks, central ossification and tendon-like tissue in the superficial tendon layers were observed in all study groups. Biomechanical test showed that samples loaded with tenocytes had significantly better failure strength/cross-section ratio (P < 0.01) compared to MSC and the control groups whereas maximum failure strength was similar in all groups. Thus, we concluded that the application of tenocytes improves the outcome in this model concerning the grade of ossification and the mechanical properties in comparison to the use of MSC or just scaffold materials.     

Patterns-based evaluation of open source BPM systems: The cases of jBPM,OpenWFE, and Enhydra Shark

In keeping with the proliferation of free software development initiatives and the increased interest in the business process management domain, many open source workflow and business process management systems have appeared during the last few years and are now under active development. This upsurge gives rise to two important questions: What are the capabilities of these systems? and How do they compare to each other and to their closed source counterparts? In other words: What is the state-of-the-art in the area?. To gain an insight into these questions, we have conducted an in-depth analysis of three of the major open source workflow management systems – jBPM, OpenWFE, and Enhydra Shark, the results of which are reported here. This analysis is based on the workflow patterns framework and provides a continuation of the series of evaluations performed using the same framework on closed source systems, business process modelling languages, and web-service composition standards. The results from evaluations of the three open source systems are compared with each other and also with the results from evaluations of three representative closed source systems: Staffware, WebSphere MQ, and Oracle BPEL PM. The overall conclusion is that open source systems are targeted more toward developers rather than business analysts. They generally provide less support for the patterns than closed source systems, particularly with respect to the resource perspective, i.e. the various ways in which work is distributed amongst business users and managed through to completion.     

Closed loop experiment design for linear time invariant dynamical systems via LMIs

All stationary experimental conditions corresponding to a discrete-time linear time-invariant causal internally stable closed loop with real rational system and feedback controller are characterized using the Youla-Kucera parametrization. Finite dimensional parametrizations of the input spectrum and the Youla-Kucera parameter allow a wide range of closed loop experiment design problems, based on the asymptotic (in the sample size) covariance matrix for the estimated parameters, to be recast as computationally tractable convex optimization problems such as semi-definite programs. In particular, for Box-Jenkins models, a finite dimensional parametrization is provided which is able to generate all possible asymptotic covariance matrices. As a special case, the very common situation of a fixed controller during the identification experiment can be handled and optimal reference signal spectra can be computed subject to closed loop signal constraints. Finally, a brief numerical comparison with closed loop experiment design based on a high model order variance expression is presented.     

Characterization and catalytic properties of perovskites with nominal compositions La1-xSrxAl1-2yCuyRuyO3

Nine different metal oxide catalysts were prepared by impregnating alumina washcoats with water solutions containing La³⁺, Sr²⁺, Cu²⁺ and Ru³⁺ ions and calcining them at 900°C. The produced samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) studies combined with energy-dispersive spectroscopy (EDS) analysis, X-ray powder diffraction and specific surface area measurements. A perovskite phase of the nominal composition La_1-xSr_xAl_1-2yCu_yRu_yO₃ was found in all samples, in increasing amount in the samples with increasing contents of strontium and ruthenium. The catalysts were evaluated with respect to light-off temperatures and redox characteristics using two gas mixtures, one containing NO/CO/C₃H₆/O₂/N₂ and the other NO/CO/N₂. The light-off temperatures for nitric oxide reduction decreased from 534 to 333°C for the catalysts without and with strontium and ruthenium, respectively. In the presence of oxygen the conversion of nitric oxide declined rapidly under oxidative conditions whereas in absence of oxygen this decline was less pronounced and found to be linear over the entire redox interval studied. These studies suggest that the perovskite phase takes an active part in the conversion of nitric oxide and carbon monoxide to nitrogen and carbon dioxide.     

Comment on “Pulsed Laser Deposition and Properties of Mn+1AXx Phase Formulated Ti3SiC2 Thin Films”

A recent paper by Hu et al. claimed synthesis of the MAX-phase Ti₃SiC₂at 100–300 °C using pulsed laser deposition. In this comment, we find that the evidence presented by Hu et al. is insufficient to show Ti₃SiC₂ formation. In fact, there is a simpler interpretation of their results from X-ray diffraction and transmission electron microscopy, namely that the material produced is a cubic TiC-based compound.     

Self-controlled visual discrimination learning of group-housed dwarf goats (Capra hircus): Behavioral strategies and effects of relocation on learning and memory.

In most studies on animal learning, individual animals are tested separately in a specific learning environment and with a limited number of trials per day. An alternative approach is to test animals in a familiar environment in their social group. In this study, the authors--applying a fully automated learning device--investigated voluntary, self-controlled visual shape discrimination learning of group-housed dwarf goats (Capra hircus). The majority of the tested goats showed successful shape discrimination, which indicates the adaptive value of an effective learning strategy. However, in each group, a few individual goats developed behavioral strategies different from shape discrimination to get reward. Relocation impairs memory retrieval (probably by attention shifting) only temporarily for previously learnt shapes. The results demonstrate the usefulness of a self-controlled learning paradigm to assess learning abilities of social species in their normal social settings. This may be especially relevant for captive animals to improve their welfare. (PsycINFO Database Record (c) 2010 APA, all rights reserved)