Evaluation of Stereolithography-Based Additive Manufacturing Technology for BaTiO3 Ceramics at 465 nm

A piezoceramic BaTiO3 material that is difficult for 3D printing was tested with a homemade laser-based stereolithography (SLA) setup. The high light absorbance of BaTiO3 in the spectral range of 350–410 nm makes this material hardly usable with most commercial SLA 3D printers. The typical polymerization depth of BaTiO3 ceramic pastes in this spectral range hardly reaches 30–50 µm for 40 vol % powder loading. A spectral change to 465 nm was realized in this work via a robot-based experimental SLA setup to improve the 3D printing efficiency. The ceramic paste was prepared from a preconditioned commercial BaTiO3 powder and used for 3D printing. The paste’s polymerization was investigated with variation of powder fraction (10–55 vol %), speed of a laser beam (1–10 mm/s, at constant laser power), and a hatching spacing (100–1000 µm). The polymerization depths of over 100 µm were routinely reached with the 465 nm SLA for pastes having 55 vol % powder loading. The spectral shift from 350–410 nm spectral region to 465 nm reduced the light absorption by BaTiO3 and remedied the photopolymerization process, emphasizing the importance of comprehensive optical analysis of prospective powders in SLA technology. Two multi-layered objects were 3D-printed to demonstrate the positive effect of the spectral shift.

Fauna and Ecology of Dipterous (Díptera, Muscidae) Livestock Biocenoses of Ukraine

The biology and ecology of parasitic insects are closely related to the life of people, and the leading role belongs to animal husbandry. It is difficult to overestimate the negative influence of parasitic dipterans on productive animals, especially during the season of their mass reproduction and distribution. The work aimed to study the species composition of Diptera in different livestock biocenoses in eastern and central Ukraine. Entomological nets and traps were used to capture zoophilic flies, the number of insects was determined using the fly index, and luminescent markers TAT 33 with a powder fraction of 30 microns. The collected insects were identified according to the existing modern identifiers. As a result of the studies, the presence of Musca domestica (Linnaeus, 1758) was determined in all livestock facilities for keeping animals and birds. The largest number of house flies was noted in the facilities for keeping sows with suckling pigs (312.0±35.3) and fattening animals (277.5±6.1). M. domestica, M. autumnalis, and S. calcitrans accounted for 75.57% of the entire complex of zoophilic flies. The species M. vitripennis, M. tempestiva, L. irritans, H. atripalpis also occupied an important place among the species that form the entomoparasitocenosis (18.91%). In pasture biotopes, two species of flies (Ortellia caesarion Meigen and Ortellia cornicina Fabr.) have been identified. They do not attack animals, but are mineralisers of cattle feces. Luminiferous marker L-1 basic green (TAT 33) fixes well on insects and lasts for 5 days. The density of the fly population in the pig houses is 36% higher than in the calf houses. The results obtained are the basis for the development of innovative, scientifically grounded schemes for control and the fight against parasitic insects at livestock enterprises

Fused Filament Fabrication of NiTi Components and Hybridization with Laser Powder Bed Fusion for Filigree Structures

The present study introduces an approach to the powder metallurgical shaping of a pseudo-elastic nickel–titanium (NiTi 44 alloy) combining two different additive manufacturing (AM) processes, namely fused filament fabrication (FFF) and laser powder bed fusion (LPBF), by manufacturing filigree structures on top of sintered FFF parts. Both processes start with commercial gas atomized NiTi powder, which is fractionated into two classes. Using the fine fraction with particle sizes <15 µm, robust thermoplastic filaments based on a non-commercial binder system were produced and processed to different auxetic and non-auxetic geometries employing a commercial standard printer. FTIR analysis for thermal decomposition products was used to develop a debinding regime. After sintering, the phase transformation austenite/martensite was characterized by DSC in as sintered and annealed state. Precipitates resulting from residual impurities were detected by micrographs and XRD. They led to an increased transformation temperature. Adjusting the oxygen and carbon content in the alloy remains a challenging issue for powder metallurgical processed NiTi alloys. Filigree lattice structures were built onto the surfaces of the sintered FFF parts by LPBF using the coarser powder fraction (15–45 µm). A good material bond was formed, resulting in the first known NiTi hybrid, which introduces new production and design options for future applications.

Lipid-lowering and anti-lipase properties of powder fractions of Dichrostachys glomerata fruits

Background: Fruits of Dichrostachys glomerata have in the last ten years benefited from special attention as a lipid-lowering plant. Recent studies show that biological activities of some plants depend on granulometry of their powder particles. Aims and Objective: The purpose of this study was to assess antihyperlipidemic, hypolipidemic, and anti-lipase properties of powder fractions of the fruits of Dichrostachys glomerata. Materials and Methods: The groups of rats on which the antihyperlipidemic test was done were fed with High Fat Diet and supplemented with powder fractions: ≥180μm, 212–180μm, 315–212μm, ≥315 μm and unsieved powder of Dichrostachys glomerata fruits at dose of 250 mg/kg for four weeks. For the hypolipidemic test, the diet was changed to normal diet and the powder fraction: 212 – 180μm, was given to rats for four weeks. Lipase inhibitory activity was determined using olive oil as substrate. Results: The antihyperlipidemic test showed that powder fractions reduced levels of total cholesterol, LDL-Cholesterol and triglycerides, groups taken powder fractions 212 –180µm and <180µm, presented the lowest values. HDL-Cholesterol levels increased, significant increases were observed in groups fed with powder fractions 315–212µm, 212–180µm, <180µm and unsieved powder. Concerning hypolipidemic test, powder fraction 212–180 µm decreased levels of total cholesterol, LDL-Cholesterol and triglycerides. 86.43% of the activity of pancreatic lipase was reduced to a concentration of 25mg/ml with an IC50 of 5mg/ml. Conclusion: Antihyperlipidemic properties of Dichrostachys glomerata fruits depended on powder fractions. Fraction 180-212μm exhibits hypolipidemic effects. The inhibition of pancreatic lipase is one of the mechanisms which could explain lipid- lowering properties of Dichrostachys glomerata fruits.

The Historic Avalanche that Destroyed the Village of Àrreu in 1803, Catalan Pyrenees

The purpose of the present study was to reconstruct the avalanche which destroyed the village of Àrreu in 1803 to solve the unknowns about this historic event, and in a broader context, to improve the knowledge about these low-frequency avalanches in the Pyrenees. To this end, a multidisciplinary approach was carried out by searching in historical sources and databases, reviewing aerial imagery, surveying the site for terrain and vegetation inspection, using dendrogeomorphological analysis, and interviewing local people, to finally apply SAMOS-AT computational simulations and the statistical α-β model. In the Monars avalanche path, 5 major avalanche events were identified, including the one in 1803. Most of these events were dense flow avalanches, but evidence of powder-fraction effects was deduced from the vegetation survey. Frequency analyses assigned a return period of more than 100 years to the 1803 event. Historical information suggests that a succession of avalanches is necessary for an event to reach the hamlet. Simulations indicate that a single avalanche of destructive size 5 would be sufficient to cause the catastrophe, and, at the same time, it would travel 1 km further down along the Àrreu river to the main valley (Noguera Pallaresa).

Effect of Powder Fraction 09CrNi2MoCu on the Structure and Properties of the Obtained Samples Using the Direct Laser Deposition

One of the disadvantages of using steel powders is the difficulty of producing such materials. In this article, steel powders from various manufacturers were discussed. The analysis of the surface, powder particles and the distribution of the fractional composition and the possibility of reuse was carried out. Direct laser deposition modes, using different laser power, were designed. From the obtained modes, tensile and impact bending samples were grown, and a comparative analysis of the obtained results was carried out.

Peat Fibers and Finely Ground Peat Powder for Application in Asphalt

In this study, the feasibility of a natural peat fiber and finely ground peat powder as a modifier for bitumen was investigated. Initially, the as-received peat material was characterized in detail: the material was ground to various degrees, separated into fiber and powder fractions, and the gradation of the powder fraction as well as the size of the fibers were determined. A possible solubility in bitumen, the moisture content, and the density of both fractions were evaluated, and a limited chemical characterization of the fibers was conducted. Secondly, the rheological behavior of the powder and the fibers when blended with bitumen was evaluated. Additionally, a limited asphalt study was conducted. The rheological data showed the stiffening effects of the powder fraction and the presence of a fiber network, which were obvious as a plateau modulus towards lower frequencies. The fiber network was strain-dependent and showed elastic effects. This was further confirmed by the multiple stress creep recovery (MSCRT) tests. These tests also indicated that the fibers should improve the rutting resistance, although it was not possible to confirm this in asphalt rutting tests. Asphalt drainage tests demonstrated that adding dry peat, whether this is ground or not, is effective in reducing the binder drainage. However, the data also revealed that the amount of added peat fibers and powder should be limited to avoid difficulties in the compaction of these asphalt mixes.

Adoption and Evaluation of a sample Pretreatment Protocol for Radiocarbon Dating of Cremated Bones at HEKAL

ABSTRACTA comparative study was undertaken to adopt and evaluate a radiocarbon (14C) preparation procedure for accelerator mass spectrometry (AMS) measurements of cremated bones at our laboratory, including different types of archaeological samples (cremated bone, bone, charcoal, charred grain). All 14C analyses were performed using the EnvironMICADAS AMS instrument at the Hertelendi Laboratory of Environmental Studies (HEKAL) and the ancillary analyses were also performed at the Institute for Nuclear Research (ATOMKI). After the physical and chemical cleaning of cremated bones, CO2 was extracted by acid hydrolysis followed by sealed-tube graphitization and 14C measurement. The supplementary δ13C measurements were also performed on CO2 gas while FTIR was measured on the powder fraction. Based on the FTIR and 14C analyses, our chemical pretreatment protocol was successful in removing contamination from the samples. Good reproducibility was obtained for the 0.2–0.3 mm fraction of blind-tested cremated samples and a maximum age difference of only 150 yr was found for the remaining case studies. This confirms the reliability of our procedure for 14C dating of cremated bones. However, in one case study, the age difference of 300 yr between two cremated fragments originating from the same urn shows that other processes affecting the cremated samples in the post-burial environment can substantially influence the 14C age, so caution must be exercised.

Studies on Grinding and Extraction of Oil from Fenugreek (Trigonella foenum-graecum) Seed

Fenugreek (Trigonella foenum-graecum) seed known for its many medicinal properties is studied for its grinding characteristics in an impact-type hammer mill. The particle size distribution (PSD) data of powder was found to regress very well with well-known mathematical Rosin–Rammler–Bennet model. Several statistical parameters of the PSD such as mass relative span, size guide number, skewness, uniformity index, uniformity coefficient were also estimated. Weight mean diameter for the entire range of grinding was between 395.8 and 620.8 µm. Specific energy consumption (32.4–115.2 kJ/kg) increased linearly with increase in size reduction ratio (4.53–7.10). Fenugreek powder fraction with less than 200 µm resulted in highest oil yield. Oil yield was found increasing with increase in size reduction ratio.

Synthesis and Characterization of Polymer Nanocomposites Containing Fe- 40 at.% Si Powder Particles Prepared by High Energy Ball Mill

Fe‒Si alloys are widely used as transformer magnets and magnetic cores because of their excellent soft magnetic properties. Fe60Si40 powders were milled in a high energy planetary ball mill (Rctsch PM400) under argon atmosphere at different time of milling. The metal powders obtained have an average diameter d50 of 2.5 to 6 um. The introduction of Si into Fe can result in a decrease of magnetic anisotropy (therefore leading to a decrease of coercivity). The nanocomposite magnetic cores were made from the Fe60Si40 powder obtained by high energy ball milling for different milling time. The particles of powder were mixed with unsaturated polyester (UP) to obtain toroidal cores. The polymerization process was made under a magnetic field H-500 Am. and ensured a preferential orientation of powder particles. Influences of the metallic powder fraction on soft magnetic properties as well as thermal increase under isothermal conditions were investigated along with the possibility to control these properties with the size and amount of powder fraction. It was also found that the soft magnetic properties of the polymer composites can be controlled in a wide range and depends on the mass fraction of the metallic powder Fe60Si40 in the composite, on shape and size of the powder particles and their orientation in the composite.