Effects of surface ligands on the charge memory characteristics of CdSe/ZnS nanocrystals in TiO2 thin film

harge memory characteristics have been systematically studied based on colloidal CdSe/ZnS nanocrystal quantum dots (QDs) embedded in similar to 50 nm-thick TiO2 film. Ligand-capped QDs showed negligible electron charging effect, implying that the electron affinity of QDs was significantly decreased by surface dipole layer surrounding QDs. In contrast, the hole charging was affected by the carrier injection blocking effect of the surface ligands. Efficient electron and hole charging characteristics were realized by removing the surface ligands via H-2 plasma treatment.open4

Near-Infrared Coronagraphic Observations of the T Tauri Binary System UY Aur

We present a near-infrared image of UY Aur, a 0.9" separated binary system, using the Coronagraphic Imager with Adaptive Optics on the Subaru Telescope. Thanks to adaptive optics, the spatial resolution of our image was ~0.1" in the full width at half maximum of the point spread function, the highest achieved. By comparison with previous measurements, we estimated that the orbital period is ~1640 yrs and the total mass of the binary is ~1.73 solar mass. The observed H-band magnitude of the secondary varies by as much as 1.3 mag within a decade, while that of the primary is rather stable. This inconstancy may arise from photospheric variability caused by an uneven accretion rate or from the rotation of the secondary. We detected a half-ring shaped circumbinary disk around the binary with a bright southwest part but a barely detectable northeast portion. The brightness ratio is ~57. Its inner radius and inclination are about 520 AU and 42, respectively. The disk is not uniform but has remarkable features, including a clumpy structure along the disk, circumstellar material inside the inner cavity, and an extended armlike structure. The circumstellar material inside the cavity probably corresponds to a clump or material accreting from the disk onto the binary. The armlike structure is a part of the disk, created by the accretion from the outer region of the disk or encounters with other stellar systems.Comment: 16 pages, 6 figures; accepted for publication in A

Quantum-dot light-emitting diodes utilizing CdSe/ZnS nanocrystals embedded in TiO(2) thin film

Quantum-dot (QD) light-emitting diodes (LEDs) are demonstrated on Si wafers by embedding core-shell CdSe/ZnS nanocrystals in TiO(2) thin films via plasma-enhanced metallorganic chemical vapor deposition. The n-TiO(2)/QDs/p-Si LED devices show typical p-n diode current-voltage and efficient electroluminescence characteristics, which are critically affected by the removal of QD surface ligands. The TiO(2)/QDs/Si system we presented can offer promising Si-based optoelectronic and electronic device applications utilizing numerous nanocrystals synthesized by colloidal solution chemistry.open181

Management of chest keloids

Keloid formation is one of the most challenging clinical problems in wound healing. With increasing frequency of open heart surgery, chest keloid formations are not infrequent in the clinical practice. The numerous treatment methods including surgical excision, intralesional steroid injection, radiation therapy, laser therapy, silicone gel sheeting, and pressure therapy underscore how little is understood about keloids. Keloids have a tendency to recur after surgical excision as a single treatment. Stretching tension is clearly associated with keloid generation, as keloids tend to occur on high tension sites such as chest region. The authors treated 58 chest keloid patients with surgical excision followed by intraoperative and postoperative intralesional steroid injection. Even with minor complications and recurrences, our protocol results in excellent outcomes in cases of chest keloids

Magnetorotationally-Driven Galactic Turbulence and the Formation of Giant Molecular Clouds

Using local 3D MHD simulations, we investigate ways in which galactic turbulence associated with the magnetorotational instability (MRI) may influence the formation and properties of GMCs. Our disk models are vertically stratified and subject to uniform shear. Initial magnetic fields are weak and purely vertical. For simplicity, we adopt an isothermal equation of state. We find that MRI-driven turbulence develops rapidly, with the saturated-state Shakura & Sunyaev parameter alpha~(0.15-0.3) dominated by Maxwell stresses. Many of the dimensionless characteristics of the turbulence (e.g. the ratio of the Maxwell to Reynolds stresses) are similar to results from previous MRI studies of accretion disks, hence insensitive to the degree of vertical disk compression, shear rate, and the presence of self-gravity. The density-weighted velocity dispersions in non- or weakly self-gravitating disks are sigma_x ~ sigma_y ~ (0.4-0.6)c_s and sigma_z~(0.2-0.3)c_s, suggesting that MRI can contribute significantly to the observed level of galactic turbulence. The saturated-state magnetic field strength B ~ 2 \mu G is similar to typical galactic values. When self-gravity is strong enough, MRI-driven high-amplitude density perturbations are swing-amplified to form Jeans-mass (~10^7 Msun) bound clouds. Compared to previous unmagnetized or strongly-magnetized disk models, the threshold for nonlinear instability in the present models occurs for surface densities at least 50% lower, corresponding to the Toomre parameter Q_th~1.6. We present evidence that self-gravitating clouds like GMCs formed under conditions similar to our models can lose much of their original spin angular momenta by magnetic braking, preferentially via fields threading near-perpendicularly to their spin axes.Comment: 39 pages, 8 figures, to appear in ApJ, vol. 599, Dec. 20, 2003; For better postscript figures and mpeg animations, see http://cfa-www.harvard.edu/~wkim/FIGURE4

Evaluation of wet-cupping therapy for persistent non-specific low back pain: a randomised, waiting-list controlled, open-label, parallel-group pilot trial

<p>Abstract</p> <p>Background</p> <p>Persistent non-specific low back pain (PNSLBP) is one of the most frequently experienced types of back pain around the world. Wet-cupping is a common intervention for various pain conditions, especially in Korea. In this context, we conducted a pilot study to determine the effectiveness and safety of wet-cupping treatment for PNSLBP.</p> <p>Methods</p> <p>We recruited 32 participants (21 in the wet-cupping group and 11 in the waiting-list group) who had been having PNSLBP for at least 3 months. The participants were recruited at the clinical research centre of the Korea Institute of Oriental Medicine, Korea. Eligible participants were randomly allocated to wet-cupping and waiting-list groups. Following the practice of traditional Korean medicine, the treatment group was provided with wet-cupping treatment at two acupuncture points among the BL23, BL24 and BL25 6 times within 2 weeks. Usual care, including providing brochures for exercise, general advice for PNSLBP and acetaminophen, was allowed in both groups. Separate assessors participated in the outcome assessment. We used the 0 to100 numerical rating scale (NRS) for pain, the McGill Pain Questionnaire for pain intensity (PPI) and the Oswestry Disability Questionnaire (ODQ), and we assessed acetaminophen use and safety issues.</p> <p>Results</p> <p>The results showed that the NRS score for pain decreased (-16.0 [95% CI: -24.4 to -7.7] in the wet-cupping group and -9.1 [-18.1 to -0.1] in the waiting-list group), but there was no statistical difference between the groups (p = 0.52). However, the PPI scores showed significant differences between the two groups (-1.2 [-1.6 to -0.8] for the wet-cupping group and -0.2 [-0.8 to 0.4] for the waiting-list group, p < 0.01). In addition, less acetaminophen was used in the wet-cupping group during 4 weeks (p = 0.09). The ODQ score did not show significant differences between the two groups (-5.60 [-8.90 to -2.30] in the wet-cupping group and -1.8 [-5.8 to 2.2] in the waiting-list group, p = 0.14). There was no report of adverse events due to wet-cupping.</p> <p>Conclusion</p> <p>This pilot study may provide preliminary data on the effectiveness and safety of wet-cupping treatments for PNSLBP. Future full-scale randomised controlled trials will be needed to provide firm evidence of the effectiveness of this intervention.</p> <p>Trial Registration</p> <p>ClinicalTrials.gov: (Identifier: <a href="http://www.clinicaltrials.gov/ct2/show/NCT00925951">NCT00925951</a>)</p> <p>Date of trial registration: June 19th, 2009</p> <p>The date when the first patient was randomised: July 15th, 2009</p> <p>The date when the study was completed: November 27th, 2009</p

Coronary Computed Tomographic Angiography at 80 kVp and Knowledge-Based Iterative Model Reconstruction Is Non-Inferior to that at 100 kVp with Iterative Reconstruction

The aims of this study were to compare the image noise and quality of coronary computed tomographic angiography (CCTA) at 80 kVp with knowledge-based iterative model reconstruction (IMR) to those of CCTA at 100 kVp with hybrid iterative reconstruction (IR), and to evaluate the feasibility of a low-dose radiation protocol with IMR. Thirty subjects who underwent prospective electrocardiogram-gating CCTA at 80 kVp, 150 mAs, and IMR (Group A), and 30 subjects with 100 kVp, 150 mAs, and hybrid IR (Group B) were retrospectively enrolled after sample-size calculation. A BMI of less than 25 kg/m2 was required for inclusion. The attenuation value and image noise of CCTA were measured and the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated at the proximal right coronary artery and left main coronary artery. The image noise was analyzed using a non-inferiority test. The CCTA images were qualitatively evaluated using a four-point scale. The radiation dose was significantly lower in Group A than Group B (0.69 ± 0.08 mSv vs. 1.39 ± 0.15 mSv, p < 0.001). The attenuation values were higher in Group A than Group B (p < 0.001). The SNR and CNR in Group A were higher than those of Group B. The image noise of Group A was non-inferior to that of Group B. Qualitative image quality of Group A was better than that of Group B (3.6 vs. 3.4, p = 0.017). CCTA at 80 kVp with IMR could reduce the radiation dose by about 50%, with non-inferior image noise and image quality than those of CCTA at 100 kVp with hybrid IR

Random telegraph noise in metallic single-walled carbon nanotubes

We have investigated random telegraph noise (RTN) observed in individual metallic carbon nanotubes (CNTs). Mean lifetimes in high- and low-current states, shigh and slow, have been studied as a function of bias-voltage and gate-voltage as well as temperature. By analyzing the statistics and features of the RTN, we suggest that this noise is due to the random transition of defects between two metastable states, activated by inelastic scattering with conduction electrons. Our results indicate an important role of defect motions in the 1=f noise in CNTs.Comment: 4 page