Optimized allylamine deposition for improved pluripotential cell culture

Deposition of allylamine (ALL) by plasma enhanced chemical vapor deposition has been optimized on silicon based models. Simultaneous energy recoil detection analysis and Rutherford backscattering spectra show that 100 W deposition is ideal in terms of polymerized film formation and H content while, lower or higher power induce reduced film retention or excessive cross linking, respectively. Surface composition of the ALL film was further probed by X-ray photoelectron spectroscopy revealing a monocomponent N 1s spectrum compatible with the presence of primary amines. Optimized ALL films were applied to polycaprolactone (PCL) surfaces after Ar plasma activation with implications in the chemistry and wettability of this biocompatible polymer. Human mesenchymal stem cells (hMSCs) were cultured on ALL coated PCL surface and controls. ALL functionalized PCL was found to be especially attractive for the formation of confluent monolayers of hMSCs after 72 h of culture.     

Dynamics and control of solar thermochemical reactors

A general dynamic model for solar-driven thermochemical processes is formulated based on unsteady mass and energy conservation equations coupled to the reaction kinetics. It is applied to two pertinent high-temperature thermochemical reactors for fuel production that make use of concentrated solar energy as the source of process heat, namely: an indirectly irradiated batch-operated packed bed reactor for the carbothermic reduction of zinc oxide, and a directly irradiated continuously operated particle flow reactor for the steam-gasification of petcoke. Model parameter identification and validation is accomplished by comparing numerically simulated and experimentally measured temperatures and outlet product concentrations. A linear feedback controller was implemented using the LQG/LTR design method. Simulations of the controlled reactor system with real solar irradiation data indicates improved quality and steadiness of product composition throughout transient solar input phases and superior solar-to-chemical energy conversion efficiency.     

Using electrophoretic deposition to identify protein charge in biological medium

Protein adsorption is the first step involved in establishing a suitable integration between a biomaterial and host tissue. It is therefore of highest interest to know the electric charge of proteins present in the relevant medium to be able to predict the behaviour of cells on given surfaces. In this study, electrophoretic deposition (EPD) was used as a simple method to identify the charge of proteins present in biological medium. In the model experiment carried out here, EPD was conducted using a biological medium containing 10% fetal calf serum (FCS) and the charge of the protein was determined by examining the migration of the protein in the EPD cell under a certain applied voltage. In addition, the suitability of EPD of proteins to deliver tailored surfaces for enhanced bioactivity or for controlled deposition of protein films on metallic surfaces was explored.     

The effect of the particle size and the morphology of alumina powders on the processing of green bodies by electrophoretic deposition

The electrophoretic deposition (EPD) method was investigated for the preparation of compacts from nanosized alumina powders. Ethanol suspensions of commercially available nanosized transition alumina and α-alumina powders were used. In addition, submicron powders were also considered for comparison. Besides the influence of operational pH change, the influence of the addition of three different surfactants – two branched polyethylene imines with molecular masses 1800 and 10,000, and citric acid—on the zeta-potential of the particles in ethanol and afterwards on the EPD was investigated.The packing density of the green parts prepared by the EPD of nanosized α-alumina powders at 30 V/cm was low (the green density was 27 vol. % of the theoretical density—TD), and a bimodal pore size distribution was observed. In contrast, the packing density in deposits made with the transition alumina nanopowder was much higher (the green density was 42 vol. % of the TD) and a monomodal distribution of pores was observed. In general, for all the deposits made from nanosized alumina powders, the particle-packing density was found to be lower than for those made from the submicron alumina powders (a green density equal to 59 vol. % of the TD).     

Mycotoxins produced by Fusarium genus in maize: determination by screening and confirmatory methods based on liquid chromatography tandem mass spectrometry

A confirmatory method for fusariotoxin analysis in maize meal, based on liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS), was developed, and compared with a previously published screening method, based on the same technique. By eluting selectively from a Carbograph-4 clean-up cartridge trichothecenes, fumonisins and macrocyclic lactones, and optimizing LC–MS/MS conditions for every chemical class, a sensitive and reliable determination was performed. Method quantification limits for confirmatory and screening methods were in the range 0.001–0.019 mg/kg and 0.003–0.125 mg/kg, respectively.     

Language/Action Meets Organisational Semiotics: Situating Conversations with Norms

Virtual professional communities require a strong co-evolution of their social and information systems. To ensure that the evolutionary process of their socio-technical systems is viable, a legitimate user-driven specification process is required. Such a process helps to ensure the meaningfulness and acceptability of specification changes. A specification method supporting this process should be grounded in the neo-humanist paradigm so that subjectivist and conflict aspects receive proper attention. Two related subfields of information science that have roots in this paradigm are the Language/Action Perspective (LAP) and organisational semiotics (OS). The RENISYS method for specification of the socio-technical systems of virtual professional communities is presented. It combines aspects from both LAP and OS, by building on work done in the DEMO (LAP) and MEASUR (OS) methodologies. It thus provides an operationalization of neo-humanist ideals that can help to extend theoretical and empirical research.     

Spectral domain analysis of conducting patches of arbitrarygeometry in multilayer media using the CG-FFT method

A conjugate gradient-fast Fourier transform (CG-FFT) scheme for analyzing finite, flat, metallic patches in multilayer structures is presented. Rooftop and razor-blade functions are considered as basis and testing functions, respectively. An equivalent periodic problem in both domains (real and spectral) is obtained and solved. Aliasing problems are avoided by performing a window on the Green's function. The spectral domain periodicity makes it feasible to take into account almost all the harmonics and to reduce the ripple in the computed current distributions. Nearly all the operations are performed in the spectral domain, including Green's function computations. Several results of convergence rates, current distributions and radar cross-section (RCS) values are given and compare favorably with measurements or results obtained by other methods