Enabling controlled dispersion in polyethylene nanocomposites using small‐angle scattering

In this article, we present some key results that demonstrate the useful application of light scattering to characterize the dispersion of nanoparticles in polymer matrix, using polyethylene nanocomposite as an example. Our results show that the dispersions of nanoparticles in polyethylene nanocomposite, that influence the thermomechanical properties of polyethylene nanocomposites, can be characterized by using small angle light scattering. This proposition is motivated by recent synthetic and morphological characterization progress towards achieving ideally dispersed polyethylene nanocomposites. Our results are significant because it is shown that using light, size and shape features that correlate well with the scanning electron microscopy observations of nanoparticle dispersion can be obtained using our unique vertical light scattering set‐up. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

The impact of supply base complexity on disruptions and performance: the moderating effects of slack and visibility

In the face of increasing supply base complexity, organisations have to develop new ways to manage or mitigate risk. This paper investigates the impact of four dimensions of complexity on the frequency of disruptions and plant performance. We apply insights from organisational information processing theory to understand how organisations can mitigate against the impact of more frequent disruptions. We test the moderating effects of slack resources as a means to absorb the effects of disruptions and supply visibility as a means to improve the ability to handle disruptions. The model is tested with data from 264 supply chain management professionals. Our findings broadly support the original hypotheses and suggest that supply base complexity can increase the frequency of disruptions and reduce plant performance but that slack resources and visibility can help to mitigate the effects. The study offers valuable insights into the management of supply base complexity.     

Profiling of bioactive compounds in cultivars of Runner and Valencia peanut market-types using liquid chromatography/APCI mass spectrometry

Peanuts are classified into four market-types (Runners, Spanish, Virginia and Valencia). Studies on their phytochemical composition have focused mainly on market-types other than Valencia. The objectives of this study are to evaluate the phytochemical composition of cultivars of Valencia and Runner market-types. Extracts of 25 peanut cultivars of Runner and Valencia market-types were analysed using HPLC-DAD-MS analysis. Results showed major differences in UV profile of the market-types. A major peak with m/z 317 identified as isorhamnetin was present only in Valencia cultivars while its glycoside (isorhamnetin-3-O-rutinoside) having m/z 625 was identified in both market-types. Genistein, daidzein, rutin, quercetin and trans-resveratrol were also identified and quantified. Genistein and daidzein concentrations (0.03 mg/100 g) were similar in both market-types. trans-Resveratrol and rutin were significantly (p < 0.05) higher in Runner cultivars while quercetin was 10-fold higher (0.60 ± 0.04 mg/100 g) in Valencia cultivars making them a better source of this phytochemical.     

In vitro stability and compatibility of tenecteplase in central venous access devices

Central venous access devices (CVADs) aid in the delivery of nutritional support, infusion therapy, and hemodialysis. Maintaining continuous flow through these devices is challenging, because they are susceptible to complications such as thrombi occlusion. Therefore, CVADs may require treatment with anticoagulant or thrombolytic agents. Using these agents as locking solutions has been widely investigated; however, few publications have described the compatibility of the therapeutic with the CVAD itself. The objective of this investigation was to evaluate the in vitro stability and compatibility of a thrombolytic biologic agent, tenecteplase, with various CVAD materials. Tenecteplase was reconstituted to 1 mg/mL with either sterile water for injection or bacteriostatic water for injection (0.9% benzyl alcohol) then incubated in glass vials, polysulfone/silicone vascular access ports, and polyurethane or silicone catheters for up to 96 hours. Biochemical assays including protein monomer, protein one-chain, and in vitro bioactivity were used to assess tenecteplase's compatibility with the investigated diluents and materials every 24 hours. Antimicrobial testing was also performed for up to 28 days on bacteriostatic water for injection-reconstituted samples only. Our results showed tenecteplase to be compatible with both types of diluents (in glass vials) and catheters for up to 72 hours. Furthermore, tenecteplase was compatible with the polysulfone/silicone vascular access ports for up to 24 hours. Finally, bacteriostatic water for injection-reconstituted tenecteplase effectively met USP criteria for the inhibition of growth of micro-organisms. This study serves as an example of a best practice to evaluate the in vitro stability and compatibility of a biologic agent with CVAD materials.     

Purification and characterization of a second aminopeptidase (pepC-like) from Lactobacillus delbrueckii subsp. bulgaricus B14

A second aminopeptidase was purified from cell-free extracts of Lactobacillus delbrueckii subsp. bulgaricus B14 by ammonium sulphate precipitation and two steps of anion-exchange chromatography. After SDS polyacrylamide-gel electrophoresis in the presence of β-mercaptoethanol, one protein band was detected at 54 kDa. The same molecular mass was estimated by gel filtration. SDS polyacrylamide-gel electrophoresis in the absence of β-mercaptoethanol resulted in a single band at 220 kDa, indicating that the enzyme forms complexes of four molecules under non-reducing conditions. Activity was markedly increased by reducing and metal-chelating agents. Thiol-group inhibitors, such as iodoacetic acid, inhibited the enzyme strongly. In contrast to Mg²⁺ and Ca²⁺, which had slightly activating effects, other divalent cations reduced enzyme activity at a concentration of 1 mM. The aminopeptidase showed highest activity at 50°C and pH 6·5–7 and hydrolyzed a wide range of di- and tripeptides. The most suitable substrates were Leu-Gly, Leu-Gly-Gly, Ala-Ala-Ala, and Met-Gly-Gly. For Leu-Gly and Leu-Gly-Gly, K_m-values of 1·81 mM and 2·17 mM and turnover numbers of 870 s⁻¹ were calculated, with a maximal rate of hydrolysis (V_max) of 4600 and 2780 μmol/min per mg of protein, respectively. The aminopeptidase did not cleave Lys-pNA, a substrate hydrolyzed by all type-‘N’ aminopeptidases from lactic acid bacteria with high velocities. It compared well, however, with pepC found in Lactococcus.     

Probing Cell‐Type‐Specific Intracellular Nanoscale Barriers Using Size‐Tuned Quantum Dots

The compartmentalization of size‐tuned luminescent semiconductor nanocrystal quantum dots (QDs) in four distinctive cell lines, which would be representative of the most likely environmental exposure routes to nanoparticles in humans, is studied. The cells are fixed and permeabilized prior to the addition of the QDs, thus eliminating any cell‐membrane‐associated effects due to active QD uptake mechanisms or to specificity of signaling routes in different cell types, but leaving intact the putative physical subcellular barriers. All quantitative assays are performed using a high content analysis (HCA) platform, thereby obtaining robust data on large cell populations. While smaller QDs 2.1 nm in diameter enter the nuclei and localize to the nucleoli in all cell types, the rate and dynamics of their passage vary depending on the cell origin. As the QD size is increased to 4.4 nm, penetration into the cell is reduced but each cell line displays its own cutoff size thresholds reflecting cell‐type‐determined cytoplasmic and nuclear pore penetration specificity. These results give rise to important considerations regarding the differential compartmentalization and susceptibility of organs, tissues, and cells to nanoparticles, and may be of prime importance for biomedical imaging and drug‐delivery research employing nanoparticle‐based probes and systems.     

Wertsch?pfung im Mobilfunkmarkt

In recent years competitive pressure in mobile markets has increased remarkably. New business models and thus new actors have entered the market. This contribution analyzes the reconfiguration of value structures and strategies in mobile markets. For this purpose, mobile network operators?? service portfolio is analyzed on the basis of a worldwide survey, and the relevant current and future value creation activities are identified with consideration of additional actors and influence factors. On that basis, roles are developed, linked with regard to value flows and combined to a reference model for the mobile market value net. Subsequently, scenario planning is used to develop a set of criteria for the construction of corresponding future scenarios and the application of the reference model is demonstrated with such a scenario.