The effect of O2 impurities on the low temperature radial thermal expansion of bundles of closed single-walled carbon nanotubes

The effect of oxygen impurities upon the radial thermal expansion (ar) of bundles of closed single-walled carbon nanotubes has been investigated in the temperature interval 2.2-48 K by the dilatometric method. Saturation of bundles of nanotubes with oxygen caused an increase in the positive ar-values in the whole interval of temperatures used. Also, several peaks appeared in the temperature dependence ar(T) above 20 K. The low temperature desorption of oxygen from powders consisting of bundles of single-walled nanotubes with open and closed ends has been investigatedComment: 7 pages, 3 figure

Quantum effects in the radial thermal expansion of bundles of single-walled carbon nanotubes doped with 4He

The radial thermal expansion (ar) of bundles of single-walled carbon nanotubes saturated with 4He impurities to the molar concentration 9.4% has been investigated in the interval 2.5-9.5 K using the dilatometric method. In the interval 2.1-3.7 K (ar) is negative and is several times higher than the negative (ar) for pure nanotube bundles. This most likely points to 4He atom tunneling between different positions in the nanotube bundle system. The excess expansion was reduced with decreasing 4He concentration.Comment: 4 pages, 1 figure, will be published in Fiz.Nizk Temp. #7, 201

Marriage & Family Therapy Students Learning Qualitative Research: Frameworks Identified Through Participatory-Observation

In this study, we used participant-observation to achieve grounded theory as we constructed a model outlining how marriage and family therapy graduate students learn qualitative research methods. We identified three major learning frameworks: Pragmatism, Ethics/Morality, and Identity of the Researcher. We also found that certain learning modalities are most congruent for students holding these major frameworks. “Critical learning incidences” appeared to cause a shift or r e -balancing of students ’ frameworks as they learn qualitative research. Application of these findings may help guide instructors who are teaching students with little previous exposure qualitative methodology. Recommendations for future research are also included

Thermal expansion of organic superconductor k-(D4-BEDT-TTF)2Cu{N(CN)2}Br. Isotopic effect

Linear thermal expansion coefficient (LTEC) of single crystal k-(D4-BEDT-TTF)2Cu[N(CN)2]Br was studied across the crystal layers in the temperature range 2-290 K using the method of precise capacitive dilatometry. Below Tc = 11,6 K the LTEC of the sample had a small negative value, which is apparently due to the transition from the paramagnetic metal in the superconducting state. There was a bend of temperature dependence of the LTEC, which shows broad peak around 40 K and can be attributed to the elastic lattice anomaly around the end-point of Mott boundary. A sharp jump in the LTEC values and hysteresis was observed in the area of Tg ~ 75-77 K, what is likely explained by the transition in a glass-like state. The isotope effect in the thermal expansion is discusses, which manifested itself in a shift of the phase transitions in comparison with fully deuterated BEDT-TTF sample.Comment: 11 pages, 6 figure

4He Sorption in Graphene Oxide at Low Temperatures

The sorption and subsequent desorption of 4He gas by grapheme oxide (GO) and hydrazine-reduced grapheme oxide (RGO-Hz) powders have been investigated in the temperature interval 2 – 25 K. It is found that the Hz-reduction of GO increases the sorptive capacitance of RGO-Hz by a factor of 3.3 in com-parison with GO. It is assumed that the sorptive capacity of the RGO-Hz sample increases because the O2-containing groups are removed in the process of Hz-reduction of GO, which makes the interlayer space ac-cessible for sorption When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3520