Aminopropylsilane treatment for the surface of porous glasses suitable for enzyme immobilisation

During silylation of porous glass with 3-aminopropyltriethoxysilane, the properties of the carrier affected the concentration of bound amino groups, the formation of aminopolysiloxane mono- or multilayer on the surface, and the hydrolytic stability of the layer formed. The influence of the carrier depended on the specific surface area and the size of pores. In contrast to silylation performed in organic solvents, in aqueous solutions a monolayer of aminopolysiloxane of high hydrolytic stability was formed on the surface of porous glass. Tetraethoxysilane modification of porous glass prior to silylation with aminosilane yields carriers of increased hydrolytic stability. Glucoamylase immobilised on carriers, that were modified in aqueous solutions, exhibit higher enzymatic activity.     

Fuzzy elements

On the basis of the theory of fuzzy sets, the fuzzy element concept is introduced. Several fuzzy elements are presented, and the stiffness matrix of fuzzy element is derived. These elements are used to modelling of infinite systems, and they don't affect the number of degrees of freedom of the system.     

A Poly(Propyleneimine) Dendrimer‐Based Polyplex‐System for Single‐Chain Antibody‐Mediated Targeted Delivery and Cellular Uptake of SiRNA

Therapeutics based on small interfering RNAs (siRNAs) offer a great potential to treat so far incurable diseases or metastatic cancer. However, the broad application of siRNAs using various nonviral carrier systems is hampered by unspecific toxic side effects, poor pharmacokinetics due to unwanted delivery of siRNA‐loaded nanoparticles into nontarget organs, or rapid renal excretion. In order to overcome these obstacles, several targeting strategies using chemically linked antibodies and ligands have emerged. This study reports a new modular polyplex carrier system for targeted delivery of siRNA, which is based on transfection‐disabled maltose‐modified poly(propyleneimine)‐dendrimers (mal‐PPI) bioconjugated to single chain fragment variables (scFvs). To achieve targeted delivery into tumor cells expressing the epidermal growth factor receptor variant III (EGFRvIII), monobiotinylated anti‐EGFRvIII scFv fused to a Propionibacterium shermanii transcarboxylase‐derived biotinylation acceptor (P‐BAP) is bioconjugated to mal‐PPI through a novel coupling strategy solely based on biotin–neutravidin bridging. In contrast to polyplexes containing an unspecific control scFv‐P‐BAP, the generated EGFRvIII‐specific polyplexes are able to exclusively deliver siRNA to tumor cells and tumors by receptor‐mediated endocytosis. These results suggest that receptor‐mediated uptake of otherwise noninternalized mal‐PPI‐based polyplexes is a promising avenue to improve siRNA therapy of cancer, and introduce a novel strategy for modular bioconjugation of protein ligands to nanoparticles.     

The influence of package-induced stresses on moulded Hall sensors

The output signals of moulded Hall sensors show changes in offset and sensitivity when the devices are affected by changing temperatures. This behaviour is a result of the differences in the thermal expansion behaviour of the package materials and is also affected by their time-dependent, viscous material properties. The stresses affected to the sensor’s sensitive layer will become effective via the piezo-Hall-effect as well as via piezo-resistivity which both change the sensitivity and the offset of the sensor’s output voltage. For modelling the stress in the sensitive area correctly it is indispensable to consider the visco-elastic and the visco-plastic behaviour of the materials constituting the package. Especially for very accurate sensors or components operating in harsh environments these effects must be regarded. In this work we investigate the thermo-mechanical stresses, which are induced in the sensitive layer of a moulded Hall sensor during the assembly process, the investigations were based mainly on finite-elements-simulations.     

New reference materials for electrochemical on-line sensors to measure steel bath composition

Further efforts have to be made to develop reliable sensors for on-line measurements in steel melts. Accurate performance of conventional sensors with a Cr-Cr₂O₃ reference over extended periods is disturbed by polarization effects mainly at the solid electrolyte/oxygen reference interface. A promising way to minimize or eliminate this problem is to reduce the flux of ionic oxygen across the solid electrolyte by applying oxygen references featuring oxygen potentials close to the actual oxygen potential of the steel melt. In search of oxygen references with 's lower than that of Cr-Cr₂O₃ mixtures, EMF measurements were made to determine the equilibrium oxygen pressures of the systems Cr-CaO-CaCr₂O₄, Cr-MgO-MgCr₂O₄, Cr-Y₂O₃-Y₂Cr₂O₆, and Nb-NbO. It is shown that the use of these reference materials enables correct on-line measurements in fully-killed steel baths over periods of 4 hours at least.     

LC multiblock copolymers containing polysulfone segments. I. Synthesis and morphology

Multiblock copolymers offer the possibility to combine the properties of different polymers. Thus, new materials with tailor-made unique properties are available by coupling of different suitable polymeric segments. The goal of the work discussed in this paper was to combine advantageous properties of liquid-crystalline polymers (LCP) with those of polysulfone (PSU). Therefore, liquid crystalline poly(ethylene terephthalate-co-1,4-oxybenzoates) were connected with PSU oligomers. Chemically homogeneous multiblock copolymers with high molecular weight were obtained by a melt transesterification procedure. It was demonstrated by wide angle x-ray scattering (WAXS), polarizing microscopy, transmission electron microscopy (TEM), and differential scanning calorimetry (DSC) that the properties of the multiblock copolymers (solid phase structure, phase behavior, morphology, glass transition, and melting behavior) can be balanced by the segment length of the incorporated blocks. The investigations clearly reveal the existence of a two-phase structure. However, a change of properties compared to the corresponding homopolymers refers to certain interactions between the phase due to the chemical connection of the LCP and PSU segments. © 1996 John Wiley & Sons, Inc.     

THERMODYNAMIC TREATMENT OF MULTICOMPONENT SYSTEMS USING INTERACTION PARAMETERS

1.IntroductionTheinteractiollparameterformalismwhichisexpressedintermsofaMacLaurinseriesexpansionforthepartialexcessfreeenergyisfrequentlyusedt0expressthethermodynamicpropertiesofdilutesoluti0ns,particularlyofmetals.However,theexperimentaldeterminationofinteractionparametersbeyondsecond-0rderisalm0stimpossibleinpracticeduetoamuchhigheraccuracyrequired.Activityc0efficients0fsolutesathighsoluteconcentrationshavesofarbeencalculatedbythefirst-orderinteractionparameters,thatis,basedonthesimplestca…