Processing of AlSi9Cu3 alloy by selective laser melting

ABSTRACT

Additive manufacturing of Al-alloys allows the production of components with a complicated structured shape, geometry composed by lattice structures, internal cooling, etc. The portfolio of Al-alloys for metal additive manufacturing is still under development and is strongly limited, compared to the conventional technology. The alloy AlSi9Cu3 is used in many applications, but its processing details are still missing. The main aim of this paper is to describe the laser process parameters for AlSi9Cu3, processed by SLM technology and manufactured from two powders of different shapes and particle sizes. The tested process parameters were laser power, laser speed, and hatch distance in the range of 100–400?W, 200–1500?mm?·?s^?1 and 90–150?µm. These were tested using a single-track and cube test. Microstructure, mechanical properties and the fatigue of SLM samples were analysed and compared with as-casted material.     

Competitive hydrogenation of olefinic substrates on a Pt/SiO2 catalyst

The effect of structure of substrates and solvents on the process of competitive hydrogenation of binary mixtures of olefinic substrates in the liquid state on 5% Pt/SiO₂ catalyst has been investigated. The hydrogenations were carried out at 20°C under atmospheric pressure of hydrogen in the absence of solvent, in methanol and in cyclohexane; one series was also performed in sec-butanol and in tert-butanol. Selectivity changed markedly owing to the different adsorptivity of the substrates. In more polar solvents hydrogenation of less polar substates was relatively preferred.     

Activity of ruthenium hydrogenation catalysts in copper(II) formate decomposition

Charcoal-, silica-, alumina- and titanium(IV) oxide-supported ruthenium catalysts, prepared by conventional impregnation and incipient wetness methods from a ruthenium(III) oxide precursor were tested in copper(II) formate decomposition in aqueous solution. Such a reaction was found to be an efficient and simple activity test of charcoal-supported catalysts. The application of this reaction for a bimetallic ruthenium–copper catalyst preparation was also suggested. Experimental results were compared with those obtained using commercial catalysts and ruthenium black.     

Shorter unentangled proofs for ground state connectivity

Can one considerably shorten a proof for a quantum problem by using a protocol with a constant number of unentangled provers? We consider a frustration-free variant of the \(\textsf {QCMA}\)-complete ground state connectivity (GSCON) problem for a system of size n with a proof of superlinear size. We show that we can shorten this proof in \(\textsf {QMA}(2)\): There exists a two-copy, unentangled proof with length of order n, up to logarithmic factors, while the completeness–soundness gap of the new protocol becomes a small inverse polynomial in n.     

FPGA-based module for SURF extraction

We present a complete hardware and software solution of an FPGA-based computer vision embedded module capable of carrying out SURF image features extraction algorithm. Aside from image analysis, the module embeds a Linux distribution that allows to run programs specifically tailored for particular applications. The module is based on a Virtex-5 FXT FPGA which features powerful configurable logic and an embedded PowerPC processor. We describe the module hardware as well as the custom FPGA image processing cores that implement the algorithm’s most computationally expensive process, the interest point detection. The module’s overall performance is evaluated and compared to CPU and GPU-based solutions. Results show that the embedded module achieves comparable distinctiveness to the SURF software implementation running in a standard CPU while being faster and consuming significantly less power and space. Thus, it allows to use the SURF algorithm in applications with power and spatial constraints, such as autonomous navigation of small mobile robots.     

A Sensor Placement Algorithm for a Mobile Robot Inspection Planning

In this paper, we address the inspection planning problem to ??see?? the whole area of the given workspace by a mobile robot. The problem is decoupled into the sensor placement problem and the multi-goal path planning problem to visit found sensing locations. However the decoupled approach provides a feasible solution, its overall quality can be poor, because the sub-problems are solved independently. We propose a new randomized approach that considers the path planning problem during solution process of the sensor placement problem. The proposed algorithm is based on a guiding of the randomization process according to prior knowledge about the environment. The algorithm is compared with two algorithms already used in the inspection planning. Performance of the algorithms is evaluated in several real environments and for a set of visibility ranges. The proposed algorithm provides better solutions in both evaluated criterions: a number of sensing locations and a length of the inspection path.     

Proteome Profiling of PMJ2-R and Primary Peritoneal Macrophages

In vitro models are often used for studying macrophage functions, including the process of phagocytosis. The application of primary macrophages has limitations associated with the individual characteristics of animals, which can lead to insufficient standardization and higher variability of the obtained results. Immortalized cell lines do not have these disadvantages, but their responses to various signals can differ from those of the living organism. In the present study, a comparative proteomic analysis of immortalized PMJ2-R cell line and primary peritoneal macrophages isolated from C57BL/6 mice was performed. A total of 4005 proteins were identified, of which 797 were quantified. Obtained results indicate significant differences in the abundances of many proteins, including essential proteins associated with the process of phagocytosis, such as Elmo1, Gsn, Hspa8, Itgb1, Ncf2, Rac2, Rack1, Sirpa, Sod1, C3, and Msr1. These findings indicate that outcomes of studies utilizing PMJ2-R cells as a model of peritoneal macrophages should be carefully validated. All MS data are deposited in ProteomeXchange with the identifier PXD022133.     

Cyclopentadienyl-Based Anticancer Drugs: Improvement of Cytotoxic Activity through Functionalisation of the π Ligand

Cytotoxic complexes containing molybdenum are widely studied as a potential substitution for commercially used drugs that often suffer from pronounced side effects and cellular resistance. Compounds of the type [(η⁵-Cp′)Mo(CO)₂(^N,NL)][BF₄], where Cp is cyclopentadienyl and ^N,NL is a bidentate ligand, are well known for their strong anticancer activity. It is a generally accepted paradigm that the nature of the coordinated ^N,NL ligand has a major impact on the cytotoxicity. In this study, a series of new functionalised Cp complexes of molybdenum was synthesised from derivatised fulvenes as π-ligand precursors. Indeed, the coordination sphere‘s modulation by various N,N-chelating ligands afforded species active toward leukemic cell line MOLT-4 with IC₅₀ values depending on the character of the N,N-chelator used. However, following study clearly showed that functionalisation of the Cp ring with an amine moiety considerably improved cytotoxicity. These results are of crucial importance for the future design of highly active cytotoxic drugs, as modification of cyclopentadienyl is believed to have a minor effect on biological activity.     

Gas‐Liquid Mass Transfer Rates and Impeller Power Consumptions for Industrial Vessel Design

Volumetric mass transfer coefficients (k_La) and power input (P) are often the key parameters in the design of gas‐liquid contactors. However, due to the limitations of most measurement methods, there is a lack of reliable data for predicting k_La for non‐coalescent batches under high energy dissipation rates. Accurate k_La and P correlations are proposed. The reliability of the correlations is ensured by using experimental data from a wide range of process conditions conducted in multiple‐impeller vessels of both laboratory scale and pilot scale, and including both non‐coalescent and coalescent batches. Applying the proposed correlations, the scale‐up and optimization of industrial vessels can be performed more accurately.