Graph-based optimization of five-axis machine tool movements by varying tool orientation

There is a relatively vast class of tool path optimization methods that minimize cost functions depending on a whole tool path. In these methods, cost functions are usually limited to convex function because the used optimization approaches cannot either handle nonsmooth functions or perform with an acceptable computational time. This paper describes a developed optimization method that finds a sequence of tool orientations that can minimize various cost functions including displacement of machine rotary axes. Every posture, tool feasible orientation can be represented in discrete fashion as nodes of a directed graph in which the edge weights denote an objective. Shortest paths are sought iteratively by applying Dijkstra’s algorithms and narrowing intervals of feasible tool orientations around the previous solution. The developed algorithm is a derivative-free optimization method working in a linear time.     

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A 4-Week Diet Low or High in Advanced Glycation Endproducts Has Limited Impact on Gut Microbial Composition in Abdominally Obese Individuals: The deAGEing Trial

Dietary advanced glycation endproducts (AGEs), abundantly present in Westernized diets, are linked to negative health outcomes, but their impact on the gut microbiota has not yet been well investigated in humans. We investigated the effects of a 4-week isocaloric and macronutrient-matched diet low or high in AGEs on the gut microbial composition of 70 abdominally obese individuals in a double-blind parallel-design randomized controlled trial ({"type":"clinical-trial","attrs":{"text":"NCT03866343","term_id":"NCT03866343"}}NCT03866343). Additionally, we investigated the cross-sectional associations between the habitual intake of dietary dicarbonyls, reactive precursors to AGEs, and the gut microbial composition, as assessed by 16S rRNA amplicon-based sequencing. Despite a marked percentage difference in AGE intake, we observed no differences in microbial richness and the general community structure. Only the Anaerostipes spp. had a relative abundance >0.5% and showed differential abundance (0.5 versus 1.11%; p = 0.028, after low- or high-AGE diet, respectively). While the habitual intake of dicarbonyls was not associated with microbial richness or a general community structure, the intake of 3-deoxyglucosone was especially associated with an abundance of several genera. Thus, a 4-week diet low or high in AGEs has a limited impact on the gut microbial composition of abdominally obese humans, paralleling its previously observed limited biological consequences. The effects of dietary dicarbonyls on the gut microbiota composition deserve further investigation.     

Structural and morphological characterization of cerium oxide nanocrystals prepared by hydrothermal synthesis

Colloidal cerium oxide (CeO2) nanocrystals prepared by hydrothermal synthesis were characterized by high-resolution transmission electron microscopy (HRTEM) and three-dimensional electron tomography (3D-ET). HRTEM images of individual CeO2 nanocrystals were then simulated by Blochwave and multislice simulations to determine the atomic arrangement and terminating atoms. The edge length distributions were between 5.0 and 8.0 nm with an average edge length of 6.7 nm. The HRTEM images showed that the CeO2 particles were slightly truncated revealing {220} facets. 3D-ET revealed that the CeO2 nanocrystals exposed predominantly {200} cubic facets. The nanocrystals were truncated at the corners exposing {111} octahedral facets and at the edges {220} dodecahedral facets. Furthermore, 3D-ET revealed the presence of some tetragonal-shaped CeO2 nanocrystals.     

Lead-Free,Luminescent Perovskite Nanocrystals Obtained through Ambient Condition Synthesis

Heterovalently substituting toxic lead is an increasingly popular design strategy to obtain environmentally sustainable variants of the exciting material class of halide perovskites. Perovskite nanocrystals (NCs) obtained through solution-based methods exhibit exceedingly high optical quality. Unfortunately, most of these synthesis routes still require reaction under inert gas and at very high temperatures. Herein a novel synthesis routine for lead-free double perovskite (LFDP) NCs is presented. An approach based upon the hot injection and ligand-assisted reprecipitation (LARP) methods to achieve a low-temperature and ambient atmosphere-based synthesis for manganese-doped Cs₂NaBiCl₆ NCs is presented. Mn incorporation is critical for the otherwise non-emissive material, with a 9:1 Bi:Mn precursor ratio maximizing the bright orange photoluminescence (PL) and quantum yield (QY). Higher synthesis temperatures slightly increase the material's performance, yet NCs synthesized at room temperature are still emissive, highlighting the versatility of the synthetic approach. While the material's indirect bandgap limits its appeal for optoelectronics, this feature could benefit photocatalysis due to longer carrier lifetimes. Moreover, the developed synthesis is facile and can rapidly be adapted to other more viable material compositions and up-scaled to realize applications directly.     

Highly Substituted Carboxymethyl Starch

Carboxymethyl starches (CMS) with a degree of substitution (DS) in the range of 0.5 to 1.5 and reagent yields about 70% were synthesised under heterogeneous reaction conditions. Starting from a standard procedure for manufacturing low substituted CMS the molar ratios of the reagents were increased. Under these conditions starch particles agglomerated during the reaction and the stirrer stopped. The reaction conditions (pulp density, addition of dispersing and water binding agents, pressure, sequence of reagents addition, reaction time, temperature, starch variety, etc.) were varied to find the best process conditions for optimum reaction efficiencies and product properties. If an amylose‐free starch, e.g. waxy corn starch is used as starting material, the obtained products are completely soluble in water to form a clear solution. The products are good viscosity regulators. Using a 2% aqueous solution a wide range of viscosity (1–90 000 mPa s) can be adjusted. The calcium‐binding capacity and the biodegradability of the products were investigated.     

Reciprocative sliding friction and wear properties of electrical discharge machined ZrO2‐based composites

Hot‐pressed, laboratory‐made, ZrO₂‐based composites with 40 vol. % WC, TiCN or TiN were surface finished by electrical discharge machining in order to compare their reciprocating sliding friction and wear response against WC–6wt%Co cemented carbide in unlubricated conditions. Sliding experiments were performed using a Plint TE77 pin‐on‐flat wear test rig, revealing a strong impact of the secondary phase on the tribological behaviour of the ZrO₂‐based composites. The worn surfaces and wear debris were characterised by scanning electron microscopy, energy dispersive X‐ray analysis and surface topography scanning, pointing out abrasion, polishing and adhesion as main wear mechanisms. The most favourable friction and wear characteristics were encountered with ZrO₂–WC composites compared to the other grades with equal amount of volumetric secondary phase. Copyright © 2009 John Wiley & Sons, Ltd.