MiHOS: an approach to support handling the mismatches between system requirements and COTS products

In the process of selecting Commercial Off-The-Shelf (COTS) products, it is inevitable to encounter mismatches between system requirements and COTS products. These mismatches occur as a result of an excess or shortage of the COTS attributes. This paper proposes a decision support approach, called MiHOS (Mismatch Handling for COTS Selection), that aims at addressing COTS mismatches during and after the selection process. MiHOS can be integrated with existing COTS selection methods at two points: (1) For evaluating COTS candidates: MiHOS estimates the anticipated fitness of the candidates if their mismatches are resolved. This helps to base our COTS selection decisions on the fitness that the candidates will eventually have if selected. (2) Mismatch resolution after selecting a COTS product: MiHOS suggests alternative plans for resolving the most appropriate mismatches using suitable actions, such that the most important risk, technical, and resource constraints are met. A case-study is used to illustrate MiHOS and to discuss its added value.

Synthese von ω-Acetyl-α-methylenpolyencarbonsäureestern

Synthesis of ω-Acetyl-α-methylenpolyene Carboxylic Esters The α-methylenpolyene carboxylic acids 1 and 2 are highly active against Gram-positive bacteria. If this activity arises from an interference with the cell membranes, then an abrupt change in biological properties is to be expected with growing chain length of simple model compounds. To make these tests possible, we describe here the synthesis of a series of homologue esters of type 40 . Their synthesis was achieved by Wittig reactions of polyene αω-dialdehydes 6 with acetyl-methylentriphenylphosphoran 5a and the protected carboxy-methylmethylen triphenylphosphonium salt 8 .     

Synthesis of thymosin β4Xen and its comparison with the natural tritetraconpeptide

Thymosin β₄^Xen, a 43 residue peptide recently isolated from Xenopus laevis, was synthesized by automatic solid phase procedure and compared with the natural product, isolated from the ovaries of Xenopus laevis For the synthesis N-methylpyrrolidone was chosen as solvent instead of the commonly used dimethylformamide because this solvent seems to be superior for solid phase peptide synthesis due to the favorable swelling properties of the polystyrene resin in this solvent and its dissolving power against the resin-bound peptide which reduces intermolecular aggregation. With acetic anhydride/pyridine and hydroxysuccinimide acetate two different acetylation reagents were tested for the final acetylation step, which gave both comparable results as shown by analytical HPLC investigations. The crude synthetic product was purified by HPLC, confirmed by ASA and LD-MS and was identical compared with the natural thymosin β₄^Xen     

Hyaluronan-coated poly(propylene imine) dendrimers as biomimetic nanocarriers of doxorubicin

A coating technology based on low molecular weight hyaluronic acid (HA) and ferulic acid (FA) was applied to the coating of low generation poly(propylene imine) dendrimers through a biocompatible hexa(ethylene glycol) spacer. The ensuing HA-FA-HEG-PPID dendrimeric materials showed interesting loading capability (between 7.65% and 9.08%) regarding anticancer agent doxorubicin, and their interactions with the drug appeared to hamper the drug release in the physiological environment. Thus, the stable nanostructured loaded delivery systems were able to internalize into cells expressing the HA receptor CD44 and to demonstrate high cytotoxicity comparable to that shown by equivalent amounts of free doxorubicin. Thus, HA-FA-HEG-PPID dendrimeric materials were proposed as biocompatible drug carriers capable of transporting anticancer doxorubicin to tumor cells.     

Characteristic Properties of an End Burning Grain with Smoke Reduced Ferrocene Containing Composite Propellant

Design, formulation and properties of an end burning grain are described which works for underwater propulsion operating at the level of 1200 N thrust for 20 s burning time. To avoid cavitational noise the formation of hot particles must be prevented. For this reason a smoke reduced composite propellant based on AP/HTPB with 86% energetic solids including 14% HMX and with 1% ferrocene derivative was adapted to grain size and motor configuration. For inhibition a pyrolytically stabilized polyurethane insulation was applied. The thermal insulation was made from a stiff high temperature resistant phenolic resin. The propellant exhibited a smooth burning behaviour with good processibility and mechanical properties. The desired performance was delivered at 120 bar operating pressure connected to 165 mm grain diameter and 93% thrust efficiency. Looking closer to the system it was found that part of the ferrocene derivative and plasticizer migrated from the propellant block to the inhibition layer. In the course of migration a small change of burning but a larger change of mechanical properties occurred in the boundary of the propellant. Despite these disadvantages burning times of 5 s and 10 s had been successfully realized with a case bonded configuration. For larger grain sizes, however, cracks occurred around the surface of the cylindrical propellant block. Calculation of the mechanical stresses which built up upon thermal shrinkage after curing and cooling showed values higher than the mechanical strength of the propellant could fit. These problems finally were overcome by a free standing grain. It led to a successful function of the motor for burning times of 20 s and more.     

cis/trans-Isomerisierung von 2,2′-Diethyl-5,5′-dimethoxy-4,4′-binaphthyliden-1,1′-dion über eine radikalische Zwischenstufe

cis/trans-Isomerization of 2,2′-Diethyl-5,5′-dimethoxy-4,4′-binaphthylidene-1,1′-dione from a Radical Intermediate The ¹H-NMR spectrum of 2,2′-diethyl-5,5′-dimethoxy-4,4′-binaphthylidene-1,1′-dione ( 1 ) shows flat-topped peaks at room temperature. At higher temperatures sharp peaks are observed while at deep temperatures the spectrum consists of two separated sets of lines. We propose a cis/trans-isomerization with coalescence at room temperature. The rate constants of this isomerization were obtained by dynamic line shape analysis, and an energy barrier of about 74 kJ mol⁻¹ was calculated. The intermediate biradical was proved by ESR spectroscopy.     

Partially Bio-Based Polyester Bead Foams via Extrusion Foaming of Poly(butylene terephthalate)/Poly(butylene furanoate) Blends

The interest in bio-based alternatives to classical polyesters such as poly(ethylene terephthalate) (PET) and poly(butylene terephthalate) (PBT) is steadily growing to achieve a more sustainable approach to polymer materials. In this study, PBT/poly(butylene furanoate) (PBF) blends are prepared, characterized and extrusion foamed. PBF as a bio-based polyester offers two advantages. The ecological footprint of the material is reduced, and additionally, it can be used in Diels-Alder reactions at the blend surface to support fusion of the foamed beads. The blending behavior of the polyesters is investigated using samples prepared in a microcompounder, particularly focused on the miscibility of the blends and transesterification reactions. The blends are thermodynamically immiscible but show a certain degree of transesterification according to nuclear magnetic resonance (NMR) spectroscopy. The morphology of blend beads produced by an extrusion foaming process is analyzed regarding their cell density, cell size distribution, and open-cell content. It is shown that PBF has a positive effect on the bead foam morphology. The use of a bifunctional linker designed for chemical fusion of the bead surfaces allows to obtaining of molded parts, in contrast to beads containing pure PBT.     

Enzymatic Late-Stage Halogenation of Peptides

The late-stage site-selective derivatisation of peptides has many potential applications in structure-activity relationship studies and postsynthetic modification or conjugation of bioactive compounds. The development of orthogonal methods for C−H functionalisation is crucial for such peptide derivatisation. Among them, biocatalytic methods are increasingly attracting attention. Tryptophan halogenases emerged as valuable catalysts to functionalise tryptophan (Trp), while direct enzyme-catalysed halogenation of synthetic peptides is yet unprecedented. Here, it is reported that the Trp 6-halogenase Thal accepts a wide range of amides and peptides containing a Trp moiety. Increasing the sequence length and reaction optimisation made bromination of pentapeptides feasible with good turnovers and a broad sequence scope, while regioselectivity turned out to be sequence dependent. Comparison of X-ray single crystal structures of Thal in complex with d -Trp and a dipeptide revealed a significantly altered binding mode for the peptide. The viability of this bioorthogonal approach was exemplified by halogenation of a cyclic RGD peptide.