Room-temperature electric field control of spin filtering efficiency for enhanced modulation of optical spin polarization in a defect-functional 0D-2D hybrid nanostructure.

In order to accomplish spin-based photoelectric information processing, it is necessary to modulate electron spin polarization in III-V semiconductor quantum dots (QDs) using an electric field. However, there is a principal limitation to the spin polarization degree and its control range, as the electron spin polarization is rapidly lost during injection into the QDs at room temperature (RT). Here, electric field control of optical spin polarization in the range of 15-40% is demonstrated at RT using InAs QDs tunnel-coupled with a defect-functional GaNAs quantum well (QW) spin filter. This compares with an electric field control of 1-4% for InAs QDs tunnel-coupled with an InGaAs QW. Transient polarization in the range of 30-60% is also obtained in the ultrafast time domain of less than 100 ps, the degree of polarization depending on the electric field. The enhanced polarization control is achieved by tuning the amplified spin polarization of electrons tunnel-injected from the GaNAs QW into QDs via the electric-field-dependent spin-filtering efficiency of GaNAs. These findings will provide a new way to extensively modulate the electron spin polarization in opto-semiconductors, by electric-field-induced on/off switching of spin amplification.

Vapor-Induced Assembly of a Platinum(II) Complex Loaded on Layered Double Hydroxide Nanoparticles.

Invited for the cover of this issue is the group of Masaki Yoshida and Masako Kato at Hokkaido University/Kwansei Gakuin University. The image depicts the changes in the assembly of PtII complexes with humidity on layered double hydroxide (LDH) nanoparticles, resulting in a drastic emission color change from green to orange. Read the full text of the article at 10.1002/chem.202301993.

Vapor-Induced Assembly of a Platinum(II) Complex Loaded on Layered Double Hydroxide Nanoparticles.

Controlled self-assembly of PtII complexes is key to the development of optical and stimuli-responsive materials, but designing and precisely controlling them is still difficult owing to weak intermolecular interactions. Herein, we report the successful water-vapor-induced assembly of an anionic PtII complex [Pt(CN)2 (ppy)]- (Hppy=2-phenylpyridine) electrostatically loaded onto cationically charged layered double hydroxide (LDH) nanoparticles consisting of Mg2+ and Al3+ ions. When the PtII complexes were densely loaded onto the LDH nanoparticles, the assembly was maintained, even in dilute aqueous media. In the case of sparse loading, the PtII complexes were loaded discretely in the dry state; however, when water vapor was adsorbed, the increased mobility of the PtII complexes led to their assembly on the LDH nanoparticles. The presence of water vapor led to a drastic change in luminescence from green to orange.

Electric-Field-Effect Spin Switching with an Enhanced Number of Highly Polarized Electron and Photon Spins Using p-Doped Semiconductor Quantum Dots.

Electric-field-effect spin switching with an enhanced number of highly polarized electron and photon spins has been demonstrated using p-doped semiconductor quantum dots (QDs). Remote p-doping in InGaAs QDs tunnel-coupled with an InGaAs quantum well (QW) significantly increased the circularly polarized, thus electron-spin-polarized, photoluminescence intensity, depending on the electric-field-induced electron spin injection from the QW as a spin reservoir into the QDs. The spin polarity and polarization degree during this spin injection can be controlled by the direction and the strength of the electric field, where the spin direction can be reversed by excess electron spin injection into the QDs via spin scattering at the QD excited states. We found that the maximum degrees of both parallel and antiparallel spin polarization to the initial spin direction in the QW can be enhanced by p-doping. The doped holes without spin polarization can effectively contribute to this electric-field-effect spin switching after the initial electron spin injection selectively removes the parallel hole spins. The optimized p-doping induces fast spin reversals at the QD excited states with a moderate electric-field application, resulting in an efficient electric-field-driven antiparallel spin injection into the QD ground state. Further excess hole doping prevents this efficient spin reversal due to multiple electron-hole spin scattering, in addition to a spin-state filling effect at the QD excited states, during the spin injection from the QW into the QDs.

Intense Red-Blue Luminescence Based on Superfine Control of Metal-Metal Interactions for Self-Assembled Platinum(II) Complexes.

A series of assembled PtII complexes comprising N-heterocyclic carbene and cyanide ligands was constructed using different substituent groups, [Pt(CN)2 (R-impy)] (R-impyH+ =1-alkyl-3-(2-pyridyl)-1H-imidazolium, R=Me (Pt-Me), Et (Pt-Et), i Pr (Pt-i Pr), and t Bu (Pt-t Bu)). All the complexes exhibited highly efficient photoluminescence with an emission quantum yield of 0.51-0.81 in the solid state at room temperature, originating from the triplet metal-metal-to-ligand charge transfer (3 MMLCT) state. Their emission colors cover the entire visible region from red for Pt-Me to blue for Pt-t Bu. Importantly, Pt-t Bu is the first example that exhibits blue 3 MMLCT emission. The 3 MMLCT emission was proved and characterized based on the temperature dependences of the crystal structures and emission properties. The wide-range color tuning of luminescence using the 3 MMLCT emission presents a new strategy of superfine control of the emission color.

Evaluation of Regional Vulnerability to Disasters by People of Ishikawa, Japan: A Cross Sectional Study Using National Health Insurance Data.

The 2013 Partial Amendment of the Disaster Countermeasures Basic Law mandated that a roster of vulnerable persons during disasters be created, and further development of evacuation support is expected. In this study, the number of vulnerable people living in target analytical areas are identified in terms of neighborhood units by using the National Health Insurance Database to create a realistic and efficient evacuation support plan. Later, after considering the "vulnerability" of an area to earthquake disaster damage, a quantitative evaluation of the state of the disaster is performed using a principle component analysis that further divided the analytical target areas into neighborhood units to make a detailed determination of the number of disaster-vulnerable persons, the severity of the disaster, etc. The results of the disaster evaluation performed after considering the vulnerability of an area are that 628 disaster-vulnerable persons live in areas with a relatively higher disaster evaluation value.

Nanometer scale fabrication and optical response of InGaN/GaN quantum disks.

In this work, we demonstrate homogeneously distributed In0.3Ga0.7N/GaN quantum disks (QDs), with an average diameter below 10 nm and a high density of 2.1 × 10(11) cm(-2), embedded in 20 nm tall nanopillars. The scalable top-down fabrication process involves the use of self-assembled ferritin bio-templates as the etch mask, spin coated on top of a strained In0.3Ga0.7N/GaN single quantum well (SQW) structure, followed by a neutral beam etch (NBE) method. The small dimensions of the iron cores inside ferritin and nearly damage-free process enabled by the NBE jointly contribute to the observation of photoluminescence (PL) from strain-relaxed In0.3Ga0.7N/GaN QDs at 6 K. The large blueshift of the peak wavelength by over 70 nm manifests a strong reduction of the quantum-confined Stark effect (QCSE) within the QD structure, which also agrees well with the theoretical prediction using a 3D Schrödinger equation solver. The current results hence pave the way towards the realization of large-scale III-N quantum structures using the combination of bio-templates and NBE, which is vital for the development of next-generation lighting and communication devices.

Light-emitting devices based on top-down fabricated GaAs quantum nanodisks.

Quantum dots photonic devices based on the III-V compound semiconductor technology offer low power consumption, temperature stability, and high-speed modulation. We fabricated GaAs nanodisks (NDs) of sub-20-nm diameters by a top-down process using a biotemplate and neutral beam etching (NBE). The GaAs NDs were embedded in an AlGaAs barrier regrown by metalorganic vapor phase epitaxy (MOVPE). The temperature dependence of photoluminescence emission energies and the transient behavior were strongly affected by the quantum confinement effects of the embedded NDs. Therefore, the quantum levels of the NDs may be tuned by controlling their dimensions. We combined NBE and MOVPE in a high-throughput process compatible with industrial production systems to produce GaAs NDs with tunable optical characteristics. ND light emitting diode exhibited a narrow spectral width of 38 nm of high-intensity emission as a result of small deviation of ND sizes and superior crystallographic quality of the etched GaAs/AlGaAs layer.

Minimally invasive radioguided parathyroidectomy for hyperparathyroidism.

Clinical or subclinical hyperparathyroidism (HPT) is one of the most common endocrine disorders. In patients with HPT who meet the indications for parathyroidectomy, complete surgical resection of all hyperfunctioning parathyroid tissue is essential for the curative treatment. The conventional surgical approach is bilateral neck exploration, whereas minimally invasive parathyroidectomy has been made possible by the introduction of (99m)Tc-sestamibi scintigraphy for preoperative localization of parathyroid adenomas. In minimally invasive surgery, the surgeon expects some modalities that predict complete resection of all hyperfunctioning parathyroid glands. The prevalence rate of (99m)Tc-sestamibi scanning for single parathyroid adenoma was widely accepted as 85-95%. Moreover, the recent developing technology of semiconductor electronics has produced useful portable gamma-probes. Intraoperative navigation using these devices provides the possibility of easy and definitive identification of parathyroid nodules during the operation. In minimally invasive radioguided parathyroidectomy using gamma-probe, different protocols are based on different timing and doses of tracer injected. Each procedure is technically easy, safe, with a low morbidity rate, and has better cosmetic results and lower overall cost than conventional bilateral neck exploration. We have applied this technique in selected patients and achieved success comparable to that achieved with contemporaneously performed standard neck exploration. In the hands of a competent surgeon, the use of sestamibi scanning and radioguided parathyroidectomy in appropriately selected patients is a useful technique.

Is the diameter or chirality distribution of single-walled carbon nanotubes selected in the synthesis process?

Based on recent theoretical photoluminescence intensity calculations, the population densities of sixteen semiconducting single-walled carbon nanotubes grown by alcohol catalytic chemical vapor deposition were estimated for two different temperatures. The profiles of population density merely as functions of tube-diameter or chiral angle are found to be widely scattered. However, systematic profiles are detectable when separately split into (2n + m), (n + 2m) and (n - m) family arrays. Apart from these well-knit family behaviors, the population densities of the group of nanotubes forming another three possible series [viz. constant-n, constant-m and constant-(n + m)] also show evidence of good correlations. Hence, a two-dimensional chiral-zone selective growth principle is hypothesized.

[Observations on three dimensional images for cracks of doweled teeth--comparison of images from specimen sections and dental tomograms from small three dimensional X-ray CT].

PURPOSE: Intraoral views of teeth with dowel and post hole taken by small three-dimensional X-ray CT (3DX) were compared with three-dimensional images from specimen sections of the same extracted teeth. This comparison shows the usefulness of 3DX for examination of cracked teeth in the oral cavity. MATERIALS AND METHODS: After taking dental tomographic images using 3DX for fractured teeth in the oral cavity, the fractured teeth were extracted and three-dimensional images for them and their cracks were obtained from a set of photographed sections. Then both sets of three-dimensional images for the fractured teeth were compared in terms of the form and region of the cracks. DISCUSSION: The tooth cracks were observed at the root face region in the intraoral view. Also, in the extracted teeth, fracture lines were recognized from the three-dimensional images. Moreover, a discontinuous image was obtained in teeth from the dental tomographic image using 3DX. This discontinuous image in teeth was observed in the same region and direction as the cracks of the three dimensional image from specimen sections of the extracted teeth. CONCLUSIONS: The discontinuous images of teeth in the dental tomographic images from 3DX were observed in the same region and direction as the cracks of teeth in the three-dimensional images from specimen sections of the extracted teeth. It was confirmed that dental tomographic images from 3DX are useful for finding cracks in living teeth. However, dental tomographic images from small three-dimensional X-ray CT are not perfectly reliable because the discontinuous image is not found in some teeth where the cracks are recognized by images from specimen sections after extraction.

Are there significant benefits of minimally invasive endoscopic thyroidectomy?

Minimally invasive surgery using endoscopic vision is widely employed for the treatment of thyroid diseases. We have performed endoscopic thyroidectomy by the axillary approach (axillary approach) and video-assisted thyroidectomy via a 3 cm cervical incision (video-assisted approach). In this study, we evaluated the efficacy of these two procedures. Each procedure was performed in 20 consecutive consenting patients. The degree of invasiveness after surgery was compared using postoperative results. The amount of pain and satisfaction with surgery was evaluated by grade (1-5) using a patient questionnaire. All thyroidectomies were completed successfully. No recurrent laryngeal nerve palsies occurred. Operating time for the video-assisted approach was significantly shorter than that for the axillary approach (p < 0.01). The amount of pain for the axillary approach on 1, 3, and 5 days after operation, respectively, was graded 3.2+/-0.7, 2.1+/-0.6, and 1.6+/-0.7 compared to 2.7+/-1.1, 1.7+/-0.7, and 1.1+/-0.2 for the video-assisted approach. The postoperative course was significantly less painful in patients undergoing the video-assisted approach on postoperative days 3 and 5 (p < 0.01). The degrees of satisfaction for the axillary approach and the video-assisted procedure were 1.2+/-0.4 and 2.4+/-1.0, respectively (p < 0.01). The video-assisted approach is less "invasive" than the axillary approach, but the axillary approach may be indicated for patients who are anxious about the visible cosmetic results.

Clinical benefits in endoscopic thyroidectomy by the axillary approach.

BACKGROUND: Surgical treatments for thyroid diseases require skin incisions that can result in prominent scars, complaints resulting from adhesions, hypesthesia, and paresthesia in the neck. We have developed an endoscopic thyroidectomy using an axillary approach. In this article, we compare our original technique with conventional open surgery from the aspects of surgical invasiveness and patients' complaints after surgery. STUDY DESIGN: Each procedure was performed in 20 patients with follicular tumors. The two groups were similar for age, gender, and the mean diameter of the thyroid tumor. No statistically significant difference in the final pathological diagnosis was found between the two groups. Surgical invasiveness and patients' complaints after surgery were compared using results of the operation and a questionnaire. RESULTS: The operating time for open surgery was significantly shorter than that for endoscopic surgery (p < 0.01). In the endoscopic surgery group, the patient questionnaires revealed that 4 patients had severe anterior chest pain on the first postoperative day. The postoperative pain decreased after, and we could not find any difference between the two groups with regard to postoperative pain. Three months after surgery, one patient who had received an endoscopic procedure complained of slight hypesthesia, and none of the patients complained of discomfort while swallowing. Among the patients who underwent open surgery, 13 patients (65%; p < 0.01) complained of hypesthesia or paresthesia and 6 patients (30%; p < 0.05) complained of discomfort while swallowing. All of the patients treated using the endoscopic procedure were satisfied with the cosmetic results, but 15 patients who underwent open surgery complained of unsatisfactory cosmetic results (p < 0.01). CONCLUSIONS: The incidence of postoperative complaints after endoscopic surgery is considerably lower than that after open surgery.

Direct mini-incision parathyroidectomy.

We describe our technique for performing a mini-incision parathyroidectomy in patients with hyperparathyroidism. Since our procedure differs from conventional parathyroidectomy in requiring a 2- or 3-cm skin incision and no raising of skin flap, this technique resulted in a good cosmetic status and less invasiveness. Hypesthesia or paresthesia in the neck and discomfort while swallowing related to a large skin incision and raising of skin flap are minimized. Although the cosmetic results of endoscopic techniques are better than those of our procedures, endoscopic instruments remain traumatic, can easily inflict iatrogenic lesions to parathyroid adenomas and enhance the risk of tumor cell exfoliation, especially if the parathyroid adenoma is manipulated by the instruments. Our surgical procedure can be less technically demanding and time-consuming. Although the number of patients whom we have treated in this manner is still small, we believe that our new procedure constitutes a useful surgical treatment for hyperparathyroidism.

Direct mini-incision thyroidectomy.

We recently developed a new surgical technique for carrying out thyroidectomy, to minimize surgical invasiveness and improve the cosmetic result. Our procedure differs from conventional thyroidectomy in requiring a 3-cm skin incision and no raising of the skin flap. Since this technique decreased tissue trauma by obviating unnecessary neck exploration, hypesthesia or paresthesia in the neck and discomfort while swallowing, related to a large skin incision and raising of the skin flap, are minimized. Since thyroidectomy is performed after delivering the thyroid gland through the small skin incision, sufficient exposure for dissection of the pretracheal and paratracheal space can be obtained. Therefore, injuring the recurrent laryngeal nerve and the parathyroid gland can be avoided. Although the number of patients that we have treated in this manner is still small, we believe that our new procedure constitutes a useful surgical treatment for patients with thyroid disease.