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Abstract

The densification behavior of H13 tool steel powder by dual speed laser scanning strategy have been characterized for selective laser melting process, one of powder bed fusion based metal 3d printing. Under limited given laser power, the laser re-melting increases the relative density and hardness of H13 tool steel with closing pores. The single melt-pool analysis shows that the pores are located on top area of melt pool when the scanning speed is over 400 mm/s while the low scanning speed of 200 mm/s generates pores beneath the melt pool in the form of keyhole mode with the high energy input from the laser. With the second laser scanning, the pores on top area of melt pools are efficiently closed with proper dual combination of scan speed. However pores located beneath the melt pools could not be removed by second laser scanning. When each layer of 3d printing are re-melted, the relative density and hardness are improved for most dual combination of scanning. Among the scan speed combination, the 600 mm/s by 400 mm/s leads to the highest relative density, 99.94 % with hardness of 53.5 HRC. This densification characterization with H13 tool steel laser re-melting can be efficiently applied for tool steel component manufacturing via metal 3d printing.

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Authors and Affiliations

Im Doo Jung
Jungho Choe
Jaecheol Yun
Sangsun Yang
Dong-Yeol Yang
Yong-Jin Kim
Ji-Hun Yu
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Abstract

Electric guitar manufacturers have used tropical woods in guitar production for decades claiming it as beneficiary to the quality of the instruments. These claims have often been questioned by guitarists but now, with many voices raising concerns regarding the ecological sustainability of such practices, the topic becomes even more important. Efforts to find alternatives must begin with a greater understanding of how tonewood affects the timbre of an electric guitar. The presented study examined how the sound of a simplified electric guitar changes with the use of various wood species. Multiple sounds were recorded using a specially designed test setup and their analysis showed differences in both spectral envelope and the generated signal level. The differences between the acoustic characteristics of tones produced by the tonewood samples explored in the study were larger than the just noticeable differences reported for the respective characteristics in the literature. To verify these findings an informal listening test was conducted which showed that sounds produced with different tonewoods were distinguishable to the average listener.
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Bibliography

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Authors and Affiliations

Jan Jasiński
1
Stanisław Oleś
1
Daniel Tokarczyk
1
Marek Pluta
1

  1. Department of Mechanics and Vibroacoustics, AGH University of Science and Technology, Cracow, Poland
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Abstract

By providing the body with essential nutrients, colostrum plays an immune and immunostimulating function. Colostrum quality depends on multiple factors, including microbial presence. This study aimed to explore the effect of non-aureus staphylococci on colostrum quality. Physical and chemical properties, fatty acid profile of cow colostrum were determined. In our study, we identified three non- aureus staphylococci species in the colostrum: S. sciuri, S. xylosus and S. warneri. The percentage of dry matter in staphylococci positive and negative colostrum samples did not differ significantly. Contents of fat, protein, and lactose in the colostrum were similar. The content of butyric (С4:0) and capric (С10:0) acids was significantly higher in the colostrum fat from samples positive for non- aureus staphylococci. Total bacterial count was lower in non- aureus staphylococci positive samples, while pH increased. The percentage of β-casein was lower in colostrum with a positive culture for non- aureus staphylococci.
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Authors and Affiliations

A. Pikhtirova
1
E. Pecka-Kiełb
2
A. Zachwieja
3
J. Bujok
2
F. Zigo
4

  1. Sumy State University, Department of Public Health, Rymskogo-Korsakova 2, Sumy 40007, Ukraine
  2. Wroclaw University of Environmental and Life Sciences, Department of Biostructure and Animal Physiology, Norwida 31, Wroclaw 50-375, Poland
  3. Wroclaw University of Environmental and Life Sciences, Department of Cattle Breeding and Milk Production, Chełmońskiego 38c, Wroclaw 51-630, Poland
  4. University of Veterinary Medicine and Pharmacy, Department of Animal Breeding, Komenskeho 73, Kosice 041 81, Slovak Republic
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Abstract

The main focus of this work was the effect of chemical alkaline treatment on Himalayan nettle fibre extraction and the characterization analysis of surface-modified nettle fibre. Nettle fibre is an eco-friendly material naturally grown in the Himalayan hills of India, and it is replacing man-made fibres. The fibres are primarily bound to each other and, in turn, to the core of the plant with pectin, lignin, and gums, which begin to break down through fungal, bacterial, enzymes and chemical treatment action. The stem from the nettle plant is fibrous and has a high-quality fibre to develop nettle yarn, which is utilized to make clothes and handicrafts, mostly aimed at generating livelihood opportunities for the rural tribe’s people. This method of extraction is an effective chemical treatment for enhancing interfacial adhesion between nettle fibres and the epoxy, which is one of the significant challenges to their usage in textiles. In this paper, nettle fibres treated with chemicals such as 1% sodium hydroxide (NaOH), 0.5% sodium sulphite (Na2SO3), 0.05% ethylenediaminetetraacetic acid (EDTA), and 2% acetic acid (CH3COOH). The impact of bacterial and chemical treatments on nettle fibre and untreated nettle fibre was characterized by Fourier transform infrared spectroscopy (FTIR) analysis, which is used to study the functional elements, Scanning electron microscopy (SEM) images revealed that there is a fibre breaking mechanism and cross-section of yarn twist formation, physical and mechanical characteristics were then determined for fibre tensile strength, fibre length, Young’s modulus, elongation break, fineness, and moisture content.
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Authors and Affiliations

R. Deepa
1
ORCID: ORCID
K. Kumaresan
1
ORCID: ORCID
K. Saravanan
2
ORCID: ORCID

  1. Bannari Amman Institute of Technology, Department of Electronics and Instrumentation Engineering, Sathyamangalam, Erode-638401, Tamilnadu, India
  2. Bannari Amman Institute of Technology, Department of Fashion Technology, Sathyamangalam, Erode-638401, Tamilnadu, India

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