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2 2011

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Factors influencing winter home ranges and activity patterns of raccoon dogs Nyctereutes procyonoides in a high-altitude area of Japan

100%

Seki Y. , Koganezawa M.

Acta Theriologica

2011

tom 56

nr 2

Between October 2006 and June 2007, we radio-tracked six adult raccoon dogs Nyctereutes procyonoides (Gray, 1834) in a high-altitude area of Japan to determine which factors influenced home ranges, daily movements, and activity patterns of Japanese raccoon dogs, with an emphasis on the winter season. The home-range sizes for the six individuals were smaller in winter than in autumn. In winter, the daily movement distances significantly decreased in response to decreasing temperature and increasing snow depth, suggesting these environmental factors contributed to a decrease in the home-range sizes during this period. Moreover, during daytime, raccoon dogs were more active in winter than in the snow-free periods (autumn and spring), and the proportion of the daytime movement distances to the total daily movement distances significantly increased as the mean daily air temperatures decreased. Therefore, it appears that the raccoon dogs in our study area passed the winter by minimizing their energy expenditure by restricting their movements when temperatures were at their lowest and snow depth was highest, and by moving more during the daytime when temperatures were higher.

Preparation and mechanical properties of graphite filled HDPE nanocomposites

51%

Sarikanat M. , Sever K. , Erbay E. , Güner F. , Tavman I. , Turgut A. , Seki Y. , Özdemir I.

Archives of Materials Science and Engineering

2011

tom Vol. 50, nr 2

120-124

Purpose: The design and manufacture of lightweight polymer composites with high electrical and thermal conductivity have been a research focus in recent years. In this study, tensile strength and modulus of elasticity of nanocomposites formed by high density polyethylene (HDPE) matrix and graphite powder filler material were determined. Design/methodology/approach: In this study the conductive filler was graphite with an average particle size of 400 nm and purity of 99.9%, the matrix material was high density polyethylene (HDPE) with a density of 0.968 g/cm3 and a melt index of 5.8 g/10 min, supplied by Petkim A.Ş.- Izmir. Nanocomposites containing up to 30 weight percent of graphite powder filler material were prepared by mixing them in a Brabender Plasticorder at 180°C for 15 minutes. Tensile strength and modulus of elasticity of nanocomposites formed were determined as functions of graphite powder content. Findings: An increase in tensile strength and modulus of elasticity was observed with increasing graphite powder content from 0 to 6%. However, for further increasing the graphite content, tensile strength decreases while modulus of elasticity continued to increase in the composite. Practical implications: Since natural graphite (NG) has a high electrical conductivity at room temperature, it is considered an ideal candidate for manufacturing conductive polymer composites. The recent advancement of nano-scale compounding technique enables the preparation of highly electrically conductive polymeric nanocomposites with low loading of conductive fillers. Nanocomposites may offer enhanced physical features such as increased stiffness, strength, barrier properties and heat resistance, without loss of impact strength in a very broad range of common synthetic or natural polymers. Originality/value: To see the effect of conducting fillers on mechanical properties of HDPE based nanocomposites, graphite particle 400 nm in size were used.