Corner-Turning Distance and Retonation Radius

All high explosives, at least the ones used in military applications, have a specific minimum detonation radius, R_min with which the detonation can change its direction through 90° or 180°. It is to be emphasized that this applies not only to thc so-called insensitive high explosives, but the sensitive explosives of course have smaller radii than the insensitive ones. The corner-turning distance, As, determined in the radial test, also corresponds to the minimum radius, R_min for the detonation wave to invert its direction through 180°. The radial test is a simple method, with regard to both design and analysis, that is suitable for determining the 90°-distance, or the minimum detonation radius, R_min.     

Enzymatic esterification of glycerol I. Lipase-catalyzed synthesis of regioisomerically pure 1,3-sn-diacylglycerols

Regioisomerically pure 1,3-sn-diacylglycerols are conveniently prepared in high yields (>80%) and in large quantities by enzymatic esterification of glycerol in the presence of various 1,3-selective lipases(Chromobacterium viscosum, Rhizopus delemar, Rhizomucor miehei) and a variety of different acyl donors like free fatty acids, fatty acid alkyl esters and vinyl esters. All reactions are carried out in aprotic organic solvents of low water content, namelyn-hexane, diethyl ether or tBuOMe. The creation of an artificial interphase between the solvent-immiscible hydrophilic glycerol and the hydrophobic reaction media by the adsorption of glycerol onto a solid support prior to use was essential for the success of these transformations. The effects of reaction conditions and the regioselectivities of the lipases on the product yields are described in detail.     

Processing of High-Density Submicrometer Al2O3 for New Applications

Sintered corundum components with submicrometer grain sizes exhibit properties which enable numerous new applications. Wet powder processing is developed to associate minimum grain sizes at highest densities with the lowest population of macrodefects. A closest ratio of powder particle size and sintered grain size is important for obtaining most fine-grained microstructures. This target was approached best by using powders with particle sizes in the range of 100–200 nm rather than with smaller nanoparticles.     

Alumina Grown during Deposition of Thermal Barrier Coatings on NiCrAlY

The microstructure of Al₂O₃ formed by oxidation of a model NiCrAlY alloy during electron-beam physical vapor deposition of ZrO₂–7.6 mol% YO_1.5 is examined and compared with that formed on the bare substrate. The growth rate, morphology, and chemical composition of the oxide vary among the different constituents of the alloy surface and are further influenced by the O₂ partial pressure and the physical presence of the thermal barrier coating (TBC) layer. These differences, however, are largely limited to the outer oxide layer. The interplay between the TBC and the growing oxide leads to the formation of a fine-grain Al₂O₃–ZrO₂"mixed zone" within the thermally grown oxide. A mechanism is outlined to explain this behavior, based on the dissolution of ZrO₂ in a transient Al₂O₃ structure growing by outward diffusion of Al, and its subsequent reprecipitation when the metastable phase transforms to the stable α-Al₂O₃ form.     

Aerobic Granular Sludge: Perspectives for Excess Sludge Management and Resource Recovery

Aerobic granular sludge (AGS) technology is gaining increasing interest globally. However, several aspects are still challenging its installation, as the integration into existing municipal wastewater treatment plants. The operation of AGS units in continuous flow mode could facilitate that integration; yet has only been experienced at lab and pilot scales. Further, handling of excess granular sludge constitutes a prominent challenge. Even that, adopting effective strategies for its management holds promising contributions to the circular economy by fostering the reuse and recovery of valuable resources. The recovery of phosphorus and alginate-like polymers holds significant commercial potential worldwide, with broad applications in agriculture, food, pharmaceuticals, and biotechnology.     

New Adhesion Promoters for Copper Leadframes and Epoxy Resin

New primer molecules have been synthesized to increase the adhesion strength between a copper leadframe and an epoxy molding compound in microelectronical devices. The coupling agents were preliminarily chemisorbed at the surface of copper plates via special binding groups like thiol, disulfide, ethylene diamine and phthalocyanine. Binding to the epoxy resin was performed via an hydroxyl group. Linear hydrocarbon spacers with various chain lengths connected the copper- and epoxy-binding groups. The self-assembled layers of the organic coupling agents at the metal surface were characterized by X-ray photoelectron spectroscopy. Thermogravimetric analysis was used to study the coating with respect to its corrosion oxidation inhibition. Shear tests clearly indicated that the coupling agents increase adhesion strength and are stable even in extreme humidity and thermal conditions in analogy to IPC-Level-1 pretreatment. Thus, delamination of the microelectronical packages was prevented.     

Oligosaccharide mimics containing galactose and fucose specifically label tumour cell surfaces and inhibit cell adhesion to fibronectin

With the aim of establishing a versatile and easy synthesis of branched saccharides for biological applications, we used molecular-dynamics simulations to model Lewis(y) to two classes of di- or triantennary saccharide mimetics. One set of mimetics was based on 1,3,5-tris(hydroxymethyl)cyclohexane (TMC) as the core, the other on furan, and both were derivatised with galactose and/or fucose. The TMC-based saccharides were biotinylated, while the furan disaccharides were treated with maleimide-activated biotin in a Diels-Alder fashion to yield oxazatricyclodecanes (OTDs). These were then assayed as cell-surface labels in human colon (SW480 and CaCo-2), liver (PLC), Glia (U333 CG 343) and ovary (SKOV-3) tumour cell lines. Discrete staining patterns were observed in all cells, usually at one or two poles of the cells, particularly with the asymmetric 3-beta-L-fucopyranosyloxymethyl-4-beta-D-galactopyranosyloxymethyl-OTD. Normal SV40-transformed fibroblasts (SV80) showed no staining. Adhesion of the highly metastatic mouse melanoma line B16 F10 to fibronectin was inhibited by 80 % by the TMC-digalactoside and by 30 % by 3,4-bis-(beta-D-galactopyranosyloxymethyl)furan. None of the saccharide mimetics inhibited the adhesion of the less metastatic B16 F1 line. Migration of B16 F10 cells through Matrigel was greatly inhibited by the TMC-digalactoside and weakly inhibited by the TMC-trigalactoside. The saccharide mimetics that had shown the best structural agreements with the terminal saccharides of Lewis(y) in the molecular dynamics simulation were also the most biologically potent compounds; this underlines the predictive nature of molecular dynamics simulations. The use of the non-saccharide cores enabled us to adapt spacer lengths and terminal saccharides to optimise the structures to bind more avidly to cell-surface lectins.     

Shaped Charge Optimisation against Bulging Targets

Equivalent to the results against explosive reactive armour sandwiches also bulging armours can be better defeated by high performance precision shaped charges compared to so‐called robust shaped charges. The shaped charges with larger liner angles or thicker liners have less jet tip velocities which results in less residual penetration capabilities.     

Photorheology of Fast UV‐Curing Multifunctional Acrylates

Summary: The fast photopolymerization of different multifunctional acrylates was analyzed by means of photorheology. The materials studied included a penta/hexaacrylate monomer and two different acrylated hyperbranched polymers. The sensitivity of the commercial rheometer was improved several‐fold, by a combination of an adaptive filter algorithm and improved data treatment, using powerful oversampling acquisition hardware. The novel set‐up was capable of monitoring up to a five orders of magnitude increase in shear modulus within short experiment timescales (about 10 s). The improvement in sensitivity and acquisition rate enabled the induction time, gelation, and vitrification of the multifunctional acrylates to be determined. In addition, the influence of UV intensity on stiffness build‐up within these materials was studied. In the case of the penta/hexaacrylate system, gelation and vitrification were detected as distinct events, in contrast to the second‐generation hyperbranched polyester, for which vitrification could not be identified. These findings are related to the difference in the glass transition temperature of the cured networks.

Absolute value of the complex shear modulus as a function of time for different acrylate monomers during UV curing.