Circular causality and indeterminism in machines for design

Presenting a hard-to-predict typography-varying system predicated on Nazi-era cryptography, the Enigma cipher machine, this paper illustrates conditions under which unrepeatable phenomena can arise, even from straight-forward mechanisms. Such conditions arise where systems are observed from outside of boundaries that arise through their observation, and where such systems refer to themselves in a circular fashion. It argues that the Enigma cipher machine is isomorphous with Heinz von Foersters portrayals of non-triviality in his non-trivial machine (NTM), but not with surprising human behaviour, and it demonstrates that the NTM does not account for spontaneity as it is observed in humans in general.     

Starch Phosphate Hydrogels. Part I: Synthesis by Mono‐phosphorylation and Cross‐linking of Starch

Starch‐based hydrogels were synthesized by cross‐linking monostarch monophosphates (MSMP) with different di‐ and tricarboxylic acids such as succinic, adipic or citric acid. Phosphorylation of starch was performed in a semi‐dry process using a mixture of primary and secondary sodium phosphates. The phosphorus content and degree of substitution of phosphate groups (DS_P) of the resulting MSMP were determined using a photometric method. For structural characterization of starch phosphates ³¹P NMR was used. Investigations showed that MSMP hydrogels were strong water absorbing polymer networks with a free swelling capacity (FSC) of up to 185 g water / g dry hydrogel.     

适度硬化表面淬火钢的加工和应用(一)

表面淬火钢的硬化程度对变速器零件的加工和应用起到决定性的作用.硬化程度主要取决于材料的化学成分,是选择表面淬火钢淬火温度的主要标准,因为稳定的材料质量是高效率大规模生产的保证.顶端淬火样品的变形和热处理条件对测量结果具有决定性的影响.由于明显的不确定性,必须考虑到顶端淬火试验测定的硬化程度和材料化学成分之间的不同.在狭窄的硬化程度范围内对表面淬火钢的热处理确保了可预测和可再现的大规模生产.一些实例表明,由于稍稍偏离所需的硬化程度范围造成不规则的热处理变形,并因成本问题而被放弃.     

The transition between high and low wear regimes under multidirectional reciprocating sliding

The wear phenomena and wear characteristics of reciprocating sliding wear with superimposed lateral vibrations were investigated using a ball-on-disc tribometer. The tribometer enabled two orthogonal oscillations, whereas one oscillation had a constant amplitude of 1 mm (primary oscillation) and the other one had a variable amplitude from 0 to 20.2 μm (secondary oscillation). Ball and disc were made of AISI 52100 steel. The ball surface was polished and the disc surface was unidirectionally grinded parallel to the direction of primary oscillation. Two regimes with different wear rates were found, being separated by a characteristic transition amplitude of 2.7 ± 0.4 μm in the secondary oscillation. This transition correlated with a change of wear mechanisms from tribochemically to mechanically dominated wear. A wear model based on surface topography and particle motion was developed. The wear model is able to predict the value of the transition amplitude by means of characteristic topographical data and the size of wear particles.     

REPLACE: a strategy for iterative design of cyclin-binding groove inhibitors

We describe a drug-design strategy termed REPLACE (REplacement with Partial Ligand Alternatives through Computational Enrichment) in which nonpeptidic surrogates for specific determinants of known peptide ligands are identified in silico by using a core peptide-bound protein structure as a design anchor. In the REPLACE application example, we present the effective replacement of two critical binding motifs in a lead protein-protein interaction inhibitor pentapeptide with more druglike phenyltriazole and diphenyl ether groups. These were identified through docking of fragment libraries into the volume of the cyclin-binding groove of CDK2/cyclin A vacated through truncation of the inhibitor peptide-binding determinants. Proof of concept for this strategy was obtained through the generation of potent peptide-small-molecule hybrids and by the confirmation of inhibitor-binding modes in X-ray crystal structures. This method therefore allows nonpeptide fragments to be identified without the requirement for a high-sensitivity binding assay and should be generally applicable in replacing amino acids as individual residues or groups in peptide inhibitors to generate pharmaceutically acceptable lead molecules.     

Engineering Potato Virus X Particles for a Covalent Protein Based Attachment of Enzymes

Plant virus nanoparticles are often used to display functional amino acids or small peptides, thus serving as building blocks in application areas as diverse as nanoelectronics, bioimaging, vaccination, drug delivery, and bone differentiation. This is most easily achieved by expressing coat protein fusions, but the assembly of the corresponding virus particles can be hampered by factors such as the fusion protein size, amino acid composition, and post‐translational modifications. Size constraints can be overcome by using the Foot and mouth disease virus 2A sequence, but the compositional limitations cannot be avoided without the introduction of time‐consuming chemical modifications. SpyTag/SpyCatcher technology is used in the present study to covalently attach the Trichoderma reesei endoglucanase Cel12A to Potato virus X (PVX) nanoparticles. The formation of PVX particles is confirmed by western blot, and the ability of the particles to display Cel12A is demonstrated by enzyme‐linked immunosorbent assays and transmission electron microscopy. Enzymatic assays show optimal reaction conditions of 50 °C and pH 6.5, and an increased substrate conversion rate compared to free enzymes. It is concluded that PVX displaying the SpyTag can serve as new scaffold for protein display, most notably for proteins with post‐translational modifications.     

Modelling for hydrogen diffusion in metals with traps revisited

A rigorous concept for diffusion of hydrogen is presented that allows for the role of trapping and/or hydrostatic stress. Nonlinear partial differential equations for the concentration of freely diffusing hydrogen in the lattice and for the total concentration of hydrogen both in the lattice and traps are derived. A generalized chemical diffusion coefficient can be deduced and is compared with reported relations from the literature. Simulation results are presented for different amounts of traps and their different energetic levels (depths), both for hydrogen concentration profiles and the total amount of hydrogen in the case of charging or discharging a cylindrical specimen. A significant charging/discharging asymmetry occurs for high hydrogen concentrations and high amounts of traps of sufficient depth. Comparisons of the chemical diffusion coefficient with experimental results from the literature are also presented.     

Laser heating of uncoated optics in a convective medium

Powerful, long-pulse lasers have a variety of applications. In many applications, optical elements are employed to direct, focus, or collimate the beam. Typically the optic is suspended in a gaseous environment (e.g., air) and can cool by convection. The variation of the optic temperature with time is obtained by combining the effects of laser heating, thermal conduction, and convective loss. Characteristics of the solutions in terms of the properties of the optic material, laser beam parameters, and the environment are discussed and compared with measurements at the Naval Research Laboratory, employing kW-class, 1 μm wavelength, continuous wave lasers and optical elements made of fused silica or BK7 glass. The calculated results are in good agreement with the measurements, given the approximations in the analysis and the expected variation in the absorption coefficients of the glasses used in the experiments.