Determination of polar drug residues in sewage and surface water applying liquid chromatography-tandem mass spectrometry

A simple and rapid method is presented for the trace-level analysis of 10 polar pharmaceutical residues in various types of water samples from the aquatic environment. Using this method, the pharmaceuticals and several drug metabolites can be analyzed in drinking and surface waters and in wastewater (treated and untreated sewage) at concentrations down to 0.01 microg/L. Samples are prepared by a simple in situ derivatization enabling the preconcentration of very polar metabolites by automated solid-phase extraction. The analytes were separated by liquid chromatography with tandem mass spectrometric detection and quantified by comparison with an internal standard. Limits of quantification were between 0.01 and 0.02 microg/L for three phenazone-type pharmaceuticals, six of their metabolites, and the antiepileptic drug carbamazepine. Except for dimethylaminophenazone, recoveries for all analytes were between 87 and 117% for raw and purified sewage, groundwater, and surface and drinking water. Investigations of some environmental samples revealed that sewage and surface water treatment causes a slight reduction of the concentrations of some analytes whereas other compounds were persistent during water treatment. Thus, some compounds were detected at the low-microgram per liter level in sewage effluents of wastewater treatment plants in Berlin (Germany) and were also found at high-nanogram per liter concentrations in Berlin surface water samples.     

Site‐Specific SERS Assay for Survivin Protein Dimer: From Ensemble Experiments to Correlative Single‐Particle Imaging

An assay for Survivin, a small dimeric protein which functions as modulator of apoptosis and cell division and serves as a promising diagnostic biomarker for different types of cancer, is presented. The assay is based on switching on surface‐enhanced Raman scattering (SERS) upon incubation of the Survivin protein dimer with Raman reporter‐labeled gold nanoparticles (AuNP). Site‐specificity is achieved by complexation of nickel‐chelated N‐nitrilo‐triacetic acid (Ni‐NTA) anchors on the particle surface by multiple histidines (His₆‐tag) attached to each C‐terminus of the centrosymmetric protein dimer. Correlative single‐particle analysis using light sheet laser microscopy enables the simultaneous observation of both elastic and inelastic light scattering from the same sample volume. Thereby, the SERS‐inactive AuNP‐protein monomers can be directly discriminated from the SERS‐active AuNP‐protein dimers/oligomers. This information, i.e. the percentage of SERS‐active AuNP in colloidal suspension, is not accessible from conventional SERS experiments due to ensemble averaging. The presented correlative single‐particle approach paves the way for quantitative site‐specific SERS assays in which site‐specific protein recognition by small chemical and in particular supramolecular ligands can be tested.     

Controlling a supplier’s subcontracting decisions through contractual enforcement or economic incentives

Suppliers often subcontract part of their workload to other suppliers, and manufacturers might suffer severe consequences if they do not anticipate their suppliers’ incentives to subcontract. In this paper, we study the case where a manufacturer outsources two tasks to a top-tier supplier. The manufacturer must decide whether it should design a contract that enforces that the different tasks are completed by the appropriate suppliers, and when it is preferable to use economic incentives to manipulate the top-tier supplier’s subcontracting behaviour. We find that when the cost difference between suppliers of different tiers is small and the correlation between the risks associated with the two tasks is minimal, the manufacturer can benefit from designing a contract that ensures the preferred subcontracting behaviour, if the cost of enforcing such a contract is not too high. However, when such enforcement cost is substantial, the manufacturer might be better off manipulating the top-tier supplier’s economic incentives.     

Characterization of Electrodeposited CuInSe2 Thin Films for Photovoltaic and Photoelectrochemical Applications

CuInSe₂ (CIS) thin films were deposited galvanostatically as well as potentiostatically by an aqueous method. The films were characterized with respect to their structural, opto-electronic and photoelectrochemical properties for application in photovoltaic and photoelectrochemical cells. The film properties depend on parameters like electrode potential, current density, deposition temperature and post-deposition heat treatment. The photoelectrochemical characterization of the film showed that electrodeposited CIS films may be used as photodiodes for hydrogen production by a photocatalytic method. The carrier concentration and flatband potential were determined from C-V measurement, and conductivity type was determined from photoelectrochemical characterization. The annealed films showed N_A = 6×l0¹⁸ cm^× and flat band potential V^B = 0.15 eV.     

Mechanical design of a 3-stage ADR for the Astro-H mission

The X-ray micro-calorimeter array in the Soft X-ray Spectrometer (SXS) instrument on Astro-H will be cooled by a 3-stage adiabatic demagnetization refrigerator (ADR). The ADR consists of two mechanically independent assemblies. When integrated with a mounting structure and the detector assembly, they form a self-contained unit that will be inserted into the top end of a liquid helium tank. The unique configuration requires many components and sub-assemblies to be thermally isolated from their structural mount. Normally in an ADR this is limited to suspending cold salt pills within their (much warmer) magnets, but in the case of SXS, it also involves one ADR stage being supported by, but thermally isolated from, the helium tank. This paper will describe the complex thermal and mechanical design of the SXS ADR, and summarize vibration and mechanical properties tests that have been performed to validate the design.     

A review on process-induced distortions of carbon fiber reinforced thermosets for large-scale production

During the manufacturing process of carbon fiber reinforced plastics, residual stresses and shape distortions occur. Analytical or numerical models can be employed to accurately predict these stresses and deformations. For a virtual compensation of a part’s geometry, an understanding of the main driving mechanisms behind process-induced distortions is essential. The present study shows main sources as well as influencing factors on stresses and distortions that arise during large-scale production of composites based on thermoset resin systems. Besides basic information on the thermal, chemical and mechanical behavior of thermoset resins and carbon fibers, state-of-the-art numerical approaches are reviewed with a focus on finite element discretization and constitutive modeling. Current virtual compensation strategies as well as possible influences of the forming operation are discussed. Finally, a conclusion is drawn that includes recommendations for future developments in the field of process-induced distortions.     

Microalgae as a potential source for biodiesel production: techniques,methods, and other challenges

This paper reviews some of the most important aspects of microalgae as a potential source for biodiesel production. Microalgae are photosynthetic microorganisms that can grow rapidly in a variety of environments because of their unicellular or multicellular structure depending on the species. They have the advantage of self‐reproduction using solar energy and converting it into chemical energy via photosynthesis. This process concludes a full cycle in a few days, obtaining higher lipid yields than terrestrial crops. This review shows several techniques and some methodologies used in the biodiesel production process from microalgae as well as the challenges that must be overcome for large‐scale process and in bio‐refineries. Copyright © 2016 John Wiley & Sons, Ltd.     

A feature-based classification of formal verification techniques for software models

Software and Systems Modeling - Software models are the core development artifact in model-based engineering (MBE). The MBE paradigm promotes the use of software models to describe structure and...