Learning experiences and identity development of Japanese nursing students through study abroad: a qualitative analysis.

OBJECTIVES: This study aimed to qualitatively analyze the experiences and perceptions of students at a nursing college in Japan who studied abroad in Asia and North America, thereby identifying the full range of benefits of study abroad programs for Japanese nursing students. METHODS: We conducted a qualitative analysis of the reflection papers and free-response questionnaire items completed by 50 Japanese undergraduate nursing students who participated in 9 study abroad programs in Asia and North America. Content analysis of the data proceeded from typological and deductive to data-driven and inductive, recursively and collaboratively. RESULTS: The results reveal perceived benefits in the areas of English language proficiency and motivation; knowledge of nursing practices, healthcare systems, and global health; cultural awareness and sensitivity; and various types of identity development (second-language motivation and identity, national/ethnic identity, professional identity, identity as a global citizen, and personal growth). It was also shown that students' perceptions of what they learned or gained varied according to the specific characteristics of each study abroad program. CONCLUSIONS: Study abroad experiences are often critical turning points that enhance nursing students' identity formation in the context of multiple and overlapping communities of practice. They also enhance core elements of the educational mission of a nursing college, particularly relating to liberal arts and internationalization. These findings can inform the development of assessment tools to be used in conjunction with study abroad programs at nursing colleges.

Direction control of quasi-stokeslet induced by thermoplasmonic heating of a water vapor microbubble.

We investigate the control of flow direction around a water vapor bubble using the thermoplasmonic effect of a gold nanoisland film (GNF) under laser irradiation with multiple spots. By focusing a laser spot on the GNF immersed in degassed water, a water vapor bubble with a diameter of ~10 µm is generated. Simultaneously, a sub laser spot was focused next to the bubble to yield a temperature gradient in the direction parallel to the GNF surface. Consequently, rapid flow was generated around the bubble, whose flow direction was dependent on the power of the sub laser spot. The observed flow was well-described using a stokeslet; the latter contained components normal and parallel to the GNF surface and was set to 10 µm above the GNF. This technique allows us to apply a significant force on the microfluid at the vicinity of the wall in the direction parallel to the wall surface, where the flow speed is generally suppressed by viscosity. It is expected to be useful for microfluidic pumping and microfluidic thermal management.

Investigation of transition from thermal- to solutal-Marangoni flow in dilute alcohol/water mixtures using nano-plasmonic heaters.

We experimentally investigated Marangoni flows around a microbubble in diluted 1-butanol/water, 2-propanol/water, and ethanol/water mixtures using the thermoplasmonic effect of gold nanoisland film. A laser spot on the gold nanoisland film acted as a highly localized heat source that was utilized to generate stable air microbubbles with diameters of 32-48 µm in the fluid and to induce a steep temperature gradient on the bubble surface. The locally heated bubble has a flow along the bubble surface, with the flow direction showing a clear transition depending on the alcohol concentrations. The fluid is driven from the hot to cold regions when the alcohol concentration is lower than the transition concentration, whereas it is driven from the cold to hot regions when the concentration is higher than the transition concentration. In addition, the transition concentration increases as the carbon number of the alcohol decreases. The observed flow direction transition is explained by the balance of the thermal- and solutal-Marangoni forces that are cancelled out for the transition concentration. The selective evaporation of the alcohol at the locally heated surface allows us to generate stable and rapid thermoplasmonic solutal-Marangoni flows in the alcohol/water mixtures.

Quasi-stokeslet induced by thermoplasmonic Marangoni effect around a water vapor microbubble.

Rapid Marangoni flows around a water vapor microbubble (WVMB) is investigated using the thermoplasmonic effect of a gold nanoisland film (GNF). By focusing a laser onto the GNF, a stable WVMB with a diameter of ~10 µm is generated in degassed water, while an air bubble generated in non-degassed water is larger than 40 µm. Under continuous heating, the WVMB involves significantly rapid Marangoni flow. This flow is well-described by a stokeslet sat ~10 µm above the surface of GNF, from which the maximum flow speed around the WVMB is estimated to exceed 1 m/s. This rapid flow generation is attributed to the small bubble size, over which the temperature is graded, and the superheat at the bubble surface in contact with the GNF. It is expected to be useful not only for microfluidic mixing but also for fundamental research on viscous flow induced by a single stokeslet.

Surface segregation in a binary mixture of ionic liquids: Comparison between high-resolution RBS measurements and moleculardynamics simulations.

Surface structure of equimolar mixture of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C2C1Im][Tf2N]) and 1-ethyl-3-methylimidazolium tetrafluoroborate ([C2C1Im][BF4]) is studied using high-resolution Rutherford backscattering spectroscopy (HRBS) and molecular dynamics (MD) simulations. Both HRBS and MD simulations show enrichment of [Tf2N] in the first molecular layer although the degree of enrichment observed by HRBS is more pronounced than that predicted by the MD simulation. In the subsurface region, MD simulation shows a small depletion of [Tf2N] while HRBS shows a small enrichment here. This discrepancy is partially attributed to the artifact of the MD simulations. Since the number of each ion is fixed in a finite-size simulation box, surface enrichment of particular ion results in its artificial depletion in the subsurface region.

Perfect Composition Depth Profiling of Ionic Liquid Surfaces Using High-resolution RBS/ERDA.

In order to reveal the surface structures of large molecular ionic liquids (ILs), the near-surface elemental depth distributions of 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([CnC1Im][Tf2N], n = 2, 6, 10) were studied using high-resolution Rutherford backscattering spectroscopy (HRBS) in combination with high-resolution elastic recoil detection analysis (HR-ERDA). The elemental depth profiles of all constituent elements, including hydrogen, were derived from HR-ERDA/HRBS measurements, so that the profiles would reproduce both HR-ERDA and HRBS spectra simultaneously. The derived elemental depth profiles agree with state-of-the-art molecular dynamics simulations, indicating the feasibility of this method. A controversy concerning the preferential orientation of [C2C1Im] at the surface has been resolved by this new combination analysis; namely, the [C2C1Im] cation has a preferential orientation with the ethyl chain pointing towards the vacuum in the topmost molecular layer.

Surface structure of imidazolium-based ionic liquids: Quantitative comparison between simulations and high-resolution RBS measurements.

Elemental depth profiles of 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([CnMIM][TFSI], n = 4, 6, 8) are measured using high-resolution Rutherford backscattering spectroscopy (HRBS). The profiles are compared with the results of molecular dynamics (MD) simulations. Both MD simulations and HRBS measurements show that the depth profiles deviate from the uniform stoichiometric composition in the surface region, showing preferential orientations of ions at the surface. The MD simulations qualitatively reproduce the observed HRBS profiles but the agreement is not satisfactory. The observed discrepancy is ascribed to the capillary waves. By taking account of the surface roughness induced by the capillary waves, the agreement becomes almost perfect.

Tracing temperature in a nanometer size region in a picosecond time period.

Irradiation of materials with either swift heavy ions or slow highly charged ions leads to ultrafast heating on a timescale of several picosecond in a region of several nanometer. This ultrafast local heating result in formation of nanostructures, which provide a number of potential applications in nanotechnologies. These nanostructures are believed to be formed when the local temperature rises beyond the melting or boiling point of the material. Conventional techniques, however, are not applicable to measure temperature in such a localized region in a short time period. Here, we propose a novel method for tracing temperature in a nanometer region in a picosecond time period by utilizing desorption of gold nanoparticles around the ion impact position. The feasibility is examined by comparing with the temperature evolution predicted by a theoretical model.

Surface structures of binary mixtures of imidazolium-based ionic liquids using high-resolution Rutherford backscattering spectroscopy and time of flight secondary ion mass spectroscopy.

Surface structures of binary mixtures of imidazolium-based ionic liquids having a common anion (bis(trifluoromethanesulfonyl)imide ([TFSI]), namely [C2MIM]1-x[C10MIM]x[TFSI] (x = 0.5 and 0.1), are studied using high-resolution Rutherford backscattering spectroscopy (HRBS) and time of flight secondary ion mass spectroscopy (TOF-SIMS). Although both measurements show surface segregation of [C10MIM] the degrees of the segregation are different. The surface fraction xsurf of [C10MIM] is estimated to be 0.6 ± 0.05 and 0.18 ± 0.02 by HRBS for x = 0.5 and 0.1, respectively. On the other hand, TOF-SIMS indicates much stronger surface segregation, namely xsurf = 0.83 ± 0.03 and 0.42 ± 0.04 for x = 0.5 and 0.1, respectively. The observed discrepancy can be attributed to the difference in the probing depth between HRBS and TOF-SIMS. The observed surface segregation can be roughly explained in terms of surface tension.

Photoacoustic emission from Au nanoparticles arrayed on thermal insulation layer.

Efficient photoacoustic emission from Au nanoparticles on a porous SiO(2) layer was investigated experimentally and theoretically. The Au nanoparticle arrays/porous SiO(2)/SiO(2)/Ag mirror sandwiches, namely, local plasmon resonators, were prepared by dynamic oblique deposition (DOD). Photoacoustic measurements were performed on the local plasmon resonators, whose optical absorption was varied from 0.03 (3%) to 0.95 by varying the thickness of the dielectric SiO(2) layer. The sample with high absorption (0.95) emitted a sound that was eight times stronger than that emitted by graphite (0.94) and three times stronger than that emitted by the sample without the porous SiO(2) layer (0.93). The contribution of the porous SiO(2) layer to the efficient photoacoustic emission was analyzed by means of a numerical method based on a one-dimensional heat transfer model. The result suggested that the low thermal conductivity of the underlying porous layer reduces the amount of heat escaping from the substrate and contributes to the efficient photoacoustic emission from Au nanoparticle arrays. Because both the thermal conductivity and the spatial distribution of the heat generation can be controlled by DOD, the local plasmon resonators produced by DOD are suitable for the spatio-temporal modulation of the local temperature.

Heat-generating property of a local plasmon resonator under illumination.

We have investigated the heat generation from gold nanoparticles resulting from their local plasma resonance. We have demonstrated the self-assembly of Au nanoparticle arrays/dielectric layer/Ag mirror sandwiches, i.e., a local plasmon resonator, using a dynamic oblique deposition technique. The thicknesses of the Au and dielectric layers were changed combinatorially on a single substrate. As a result, local plasmon resonator chips were successfully fabricated. Because of strong interference, their optical absorption can be controlled between 0.0% and 97% in the near-IR region, depending on the thickness of the dielectric layer. We evaluated the heat generation from Au nanoparticles by measuring the temperature of water with which a cell prepared on a chip is filled under laser illumination. The change in the water temperature is proportional to the optical absorption of the local plasmon resonator chips. This suggests that the photothermal conversion efficiency can be controlled by interference. These features make the application of the local plasmon resonator to nanoheaters, which can spatiotemporally control heat generation, suitable.

Observation of surface structure of 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide using high-resolution Rutherford backscattering spectroscopy.

The surface structures of 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C(n)MIM][TFSI], n=2,4,6) are studied by high-resolution Rutherford backscattering spectroscopy. The average composition of the surface molecular layer is very close to the stoichiometric composition, showing that neither ion is enriched in the surface layer. A detailed analysis indicates that both cations and anions have preferential molecular orientations at the surface. The alkyl chains of the [C(n)MIM] cations protrude to the vacuum and the CF(3) groups of the [TFSI] anions are also pointing toward the vacuum. While the orientation of the [TFSI] anion becomes weaker with increasing alkyl-chain length, the protrusion of the alkyl chain occurs irrespective of the chain length. It was also found that the N(SO(2))(2) moiety is located nearly at the same depth as the imidazolium ring, suggesting that one of oxygen atoms in [TFSI] is bonded to the hydrogen of the C(2) carbon atom of the imidazolium ring.

Analysis of ultra-thin HfO(2)/SiON/Si(001): comparison of three different techniques.

Composition depth profiling of HfO(2) (2.5 nm)/SiON (1.6 nm)/Si(001) was performed by three diffetent analytical techniques: high-resolution Rutherford backscattering spectroscopy (HRBS), angle-resolved X-ray photoelectron spectroscopy (AR-XPS) and high-resolution elastic recoil detection (HR-ERD). By comparing these results we found the following: (1) HRBS generally provides accurate depth profiles. However, care must be taken in backgroud subtraction for depth profiling of light elements. (2) In the standard AR-XPS analysis, a simple exponential formula is often used to calculate the photoelectron escape probability. This simple formula, however, cannot be used for the precise depth profiling. (2) Although HR-ERD is the most reliable technique for the depth profiling of light elements, it may suffer from multiple scattering, which deteriorates the depth resolution, and also may cause a large background.

Observation of surface structure of 1-butyl-3-methylimidazolium hexafluorophosphate using high-resolution Rutherford backscattering spectroscopy.

The surface structure of 1-butyl-3-methylimidazolium hexafluorophosphate is studied by high-resolution Rutherford backscattering spectroscopy (HRBS) at room temperature. Elemental depth profiles are derived from the observed HRBS spectrum through spectrum simulation. While the obtained carbon profile has a sharp peak at the surface, the nitrogen profile shows a broader peak at a depth approximately 0.3 nm. These observations indicate that the butyl chain protrudes from the bulk liquid to the vacuum at the surface. The profiles of phosphorous and fluorine also have a broad peak at almost the same depth as the nitrogen profile, indicating that the anions are located near the imidazolium rings. These results are in good agreement with recent molecular dynamics simulations.

Observation of molecular ordering at the surface of trimethylpropylammonium bis(trifluoromethanesulfonyl)imide using high-resolution rutherford backscattering spectroscopy.

The surface structure of trimethylpropylammonium bis(trifluoromethanesulfonyl)imide ([TMPA] [TFSI]) is studied by high-resolution Rutherford backscattering spectroscopy at room temperature. The results provide direct evidence of the molecular ordering at the surface. The C1 conformer of the [TFSI] anion is dominant among two stable conformers, and the anions are oriented with their CF3 groups pointing toward the vacuum in the outermost molecular layer. The anions in the second molecular layer also show preferred orientation although it is rather weak.

Ag nanorod arrays tailored for surface-enhanced Raman imaging in the near-infrared region.

Using a dynamic oblique angle deposition technique, we demonstrate the direct formation of Ag nanorods with quasi-parallel major axes on a template layer of oxide having a strongly anisotropic surface morphology. The optical properties of the nanorods are tuned by varying the deposition conditions without any pre- or post-treatment, and the resulting Ag nanorod arrays exhibit high surface-enhanced Raman scattering (SERS) activity. In addition to high macroscopic uniformity over a large area, our nanorod arrays contain a high density of isolated nanorods. Using the optimum Ag nanorod arrays, the SERS imaging of the microdroplets of a rhodamine 6G solution is successfully demonstrated. The space resolution of the imaging is of the order of at least a few µm. These features are suitable for the SERS imaging of biomaterials.

Au nanorod arrays tailored for surface-enhanced Raman spectroscopy.

We have demonstrated surface-enhanced Raman spectroscopy (SERS) on arrays of Au nanorods aligned in line by a dynamic oblique deposition technique. For light polarized along the major axes of the nanorods, the plasma resonance of the Au nanorods has been tuned to a wavelength suitable for Raman spectroscopy. Raman scattering on the discrete nanorods is significantly enhanced compared with that on semicontinuous Au films. Since the preparation process is physically bottom-up, it is robust in its selection of the materials and is useful for providing SERS sensors at low cost.