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Modified Wood of Black Locust - Alternative to Honduran Rosewood in the Production of Xylophones

100%
Danihelová A., Čulík M., Němec M., Gejdoš M., Danihelová Z.
Acta Physica Polonica A
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2015
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vol. 127
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issue 1
106-109
EN
Traditionally, exotic hardwoods are used for the production of xylophone or concert marimba. Mainly the Honduran rosewood shows the optimal properties (high density, high modulus of elasticity, speed of sound, hardness, low damping) considering the required acoustic quality of the xylophone. The Honduran rosewood is listed in CITES Appendix II, therefore it is necessary to look for possibilities of its replacement by other wood species. However, the density, hardness and strength properties of the European wood species are rated less than Honduran rosewood. Therefore it is clear that there is a need to search for alternative of exotic wood. Our research indicates that the Honduran rosewood can be replaced by European wood species; however it is necessary to modify their properties. As convenient modification of domestic wood species appear: mechanical modification (densification), thermal modification or a combination of these two methods. Thus we can obtain wood with properties similar to the properties of exotic wood. The study presents the comparison of physical and acoustical characteristics of modified wood of Black locust with the characteristics of the Honduran rosewood. Also, the sound quality of xylophone made from Black locust wood before and after modification was investigated.
2
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Differences in the Modal and Structural Parameters of Resonance and Non-Resonance Wood of Spruce ({ em Picea abies} L.)

100%
Mania P., Fabisiak E., Skrodzka E.
Acta Physica Polonica A
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2015
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vol. 127
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issue 1
110-113
EN
Results of modal analysis and evaluation of cyclic inhomogeneity of wood and cell wall ultrastructure of a resonance and non-resonance spruce wood (Picea abies L.) are presented. The resonance wood came from a tree from Istebna, while the non-resonance wood came from a tree from the vicinity of Olsztyn. Modal analysis was made by a pulse excitation. The resonance and non-resonance wood differ in the fundamental modal parameters as well as in the number of vibrational modes. Macrostructural parameters of the wood samples were also measured. The angles of cellulose microfibrils in tangent walls of tracheids (microfibril angles or MFA) within individual annual rings were measured. The resonance wood was found to show high cyclic homogeneity of macro- and ultrastructural features.
3
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The Effect of Wood on the Sound Quality of Electric String Instruments

100%
Puszyński J., Moliński W., Preis A.
Acta Physica Polonica A
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2015
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vol. 127
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issue 1
114-116
EN
The objective of the study was to investigate the influence of wood species on sound timbre generated by electric string instruments. The obtained results allow to conclude that wood species have the largest influence on the specific sound loudness and it correlates with density and modulus of elasticity. The greater differences occur at lower frequencies. There was no correlation between signal recorded by microphone and pickup.
4
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Fifty Years of Study of the Piezoelectric Properties of Macromolecular Structured Biological Materials

80%
Kryszewski M.
Acta Physica Polonica A
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2004
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vol. 105
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issue 4
389-408
EN
The piezoelectricity of biopolymers was discovered by E. Fukada for wood and bone in the fifties. This paper induced a number of studies on piezoelectric behaviour of bone collagen and tendon in wet and dry conditions as well as in many biological substances: polysaccharides, proteins, and biodegradable, optically active oriented films of poly(L-lactic acid). The implantation of this polymer induced the growth of bone, possibly because the ionic current caused by piezoelectric polarization stimulated the activity of bone cells. The phenomenon of bone growth has been discussed in terms of application of various substances, particularly modified collagen. The healing process of bone growth is still open both from the view of mechanism and biocompatibilities of materials used for this purpose. Fukada's group has a leading position in these studies. The fifty years of study of piezoelectricity in biomaterials resulted in many important observations and indication for further promising experimental and theoretical studies which will help to discover new ways and new materials for the tissue reconstruction.
5
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Rheological Behavior of Modified Starch/EVA Blends

80%
Aydin I., Ergin M., Altun M.
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vol. 125
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issue 2
503-505
EN
There is a current research tendency towards the biodegradable thermoplastic materials from renewable resources since the environmental restraints play vital role in recent years. Starch is one of the renewable resources and abundantly available in the form of plant products. It is possible to blend starch with various thermoplastic materials to achieve such aims. In this study, an ethylene-vinyl acetate (EVA) copolymer resin (Luvax 40 W, DuPont) was blended with a modified starch (Maize Starch, Pendik Nisasta) in various amounts by means of a single screw extruder with different screw speeds. For this purpose, first starch was modified in a four neck spherical glass reactor. Modified starch was then blended with the EVA copolymer resin. Rheological analyses of these composites were performed by means of an AR G2 rheometer (TA Instruments) with parallel-plate geometry in a steady state condition. Rheological behavior and properties were recorded. The changes in viscosity with different temperatures, stress and strain dependence as well as general constitutive material behavior were determined in detail. As a result, the best formulation and process conditions were determined for the reasonable processability of starch/EVA blends from the obtained rheological data.
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