Insulated π-Conjugated Azido Scaffolds for Stepwise Functionalization via Huisgen Cycloaddition on Metal Oxide Surfaces.

In organic-inorganic hybrid devices, fine interfacial controls by organic components directly affect the device performance. However, fabrication of uniformed interfaces using π-conjugated molecules remains challenging due to facile aggregation by their strong π-π interaction. In this report, a π-conjugated scaffold insulated by covalently linked permethylated α-cyclodextrin moiety with an azido group is synthesized for surface Huisgen cycloaddition on metal oxides. Fourier-transformed infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy confirm the successful immobilization of the insulated azido scaffold on ZnO nanowire array surfaces. Owing to the highly independent immobilization, the scaffold allows rapid and complete conversion of the surface azido group in Huisgen cycloaddition reactions with ethynyl-terminated molecules, as confirmed by FT-IR spectroscopy monitoring. Cyclic voltammetry analysis of modified indium tin oxide substrates shows the positive effects of cyclic insulation toward suppression of intermolecular interaction between molecules introduced by the surface Huisgen cycloaddition reactions. The utility of the scaffold for heterogeneous catalysis is demonstrated in electrocatalytic selective O2 reduction to H2O2 with cobalt(II) chlorin modified fluorine doped tin oxide electrode and photocatalytic H2 generation with iridium(III) dye-sensitized Pt-loaded TiO2 nanoparticle. These results highlight the potential of the insulated azido scaffold for a stepwise functionalization process, enabling precise and well-defined hybrid interfaces.

Observation of anisotropic magneto-Peltier effect in nickel.

The Peltier effect, discovered in 1834, converts a charge current into a heat current in a conductor, and its performance is described by the Peltier coefficient, which is defined as the ratio of the generated heat current to the applied charge current1,2. To exploit the Peltier effect for thermoelectric cooling or heating, junctions of two conductors with different Peltier coefficients have been believed to be indispensable. Here we challenge this conventional wisdom by demonstrating Peltier cooling and heating in a single material without junctions. This is realized through an anisotropic magneto-Peltier effect in which the Peltier coefficient depends on the angle between the directions of a charge current and magnetization in a ferromagnet. By using active thermography techniques3-10, we observe the temperature change induced by this effect in a plain nickel slab. We find that the thermoelectric properties of the ferromagnet can be redesigned simply by changing the configurations of the charge current and magnetization, for instance, by shaping the ferromagnet so that the current must flow around a curve. Our experimental results demonstrate the suitability of nickel for the anisotropic magneto-Peltier effect and the importance of spin-orbit interaction in its mechanism. The anisotropic magneto-Peltier effect observed here is the missing thermoelectric phenomenon in ferromagnetic materials-the Onsager reciprocal of the anisotropic magneto-Seebeck effect previously observed in ferromagnets-and its simplicity might prove useful in developing thermal management technologies for electronic and spintronic devices.

Publisher Correction: Observation of anisotropic magneto-Peltier effect in nickel.

In this Letter, owing to an error during the production process, 'θH' was incorrectly written as 'θΗH' six times in the paragraph starting "Up to now,…". These errors have been corrected online.

Observation of the Anisotropic Magneto-Thomson Effect.

We report the observation of the anisotropic magneto-Thomson effect (AMTE), which is one of the higher-order thermoelectric effects in a ferromagnet. Using lock-in thermography, we demonstrated that in a ferromagnetic NiPt alloy, the cooling or heating induced by the Thomson effect depends on the angle between the magnetization direction and the temperature gradient or charge current applied to the alloy. AMTE observed here is the missing ferromagnetic analog of the magneto-Thomson effect in a nonmagnetic conductor, providing the basis for nonlinear spin caloritronics and thermoelectrics.

Seebeck-driven transverse thermoelectric generation.

When a temperature gradient is applied to a closed circuit comprising two different conductors, a charge current is generated via the Seebeck effect1. Here, we utilize the Seebeck-effect-induced charge current to drive 'transverse' thermoelectric generation, which has great potential for energy harvesting and heat sensing applications owing to the orthogonal geometry of the heat-to-charge-current conversion2-9. We found that, in a closed circuit comprising thermoelectric and magnetic materials, artificial hybridization of the Seebeck effect into the anomalous Hall effect10 enables transverse thermoelectric generation with a similar symmetry to the anomalous Nernst effect11-27. Surprisingly, the Seebeck-effect-driven transverse thermopower can be several orders of magnitude larger than the anomalous-Nernst-effect-driven thermopower, which is clearly demonstrated by our experiments using Co2MnGa/Si hybrid materials. The unconventional approach could be a breakthrough in developing applications of transverse thermoelectric generation.

Thermoelectric Polarization Transport in Ferroelectric Ballistic Point Contacts.

We formulate a scattering theory of polarization and heat transport through a ballistic ferroelectric point contact. We predict a polarization current under either an electric field or a temperature difference that depends strongly on the direction of the ferroelectric order and can be detected by its magnetic stray field and associated thermovoltage and Peltier effect.

Sm-Co-based amorphous alloy films for zero-field operation of transverse thermoelectric generation.

Transverse thermoelectric generation using magnetic materials is essential to develop active thermal engineering technologies, for which the improvements of not only the thermoelectric output but also applicability and versatility are required. In this study, using combinatorial material science and lock-in thermography technique, we have systematically investigated the transverse thermoelectric performance of Sm-Co-based alloy films. The high-throughput material investigation revealed the best Sm-Co-based alloys with the large anomalous Nernst effect (ANE) as well as the anomalous Ettingshausen effect (AEE). In addition to ANE/AEE, we discovered unique and superior material properties in these alloys: the amorphous structure, low thermal conductivity, and large in-plane coercivity and remanent magnetization. These properties make it advantageous over conventional materials to realize heat flux sensing applications based on ANE, as our Sm-Co-based films can generate thermoelectric output without an external magnetic field. Importantly, the amorphous nature enables the fabrication of these films on various substrates including flexible sheets, making the large-scale and low-cost manufacturing easier. Our demonstration will provide a pathway to develop flexible transverse thermoelectric devices for smart thermal management.

Theory of Transport in Ferroelectric Capacitors.

The spontaneous order of electric and magnetic dipoles in ferroelectrics and ferromagnets even at high temperatures is both fascinating and useful. Transport of magnetism in the form of spin currents is vigorously studied in spintronics, but the polarization current of the ferroelectric order has escaped attention. We therefore present a time-dependent diffusion theory for heat and polarization transport in a planar ferroelectric capacitor with parameters derived from a one-dimensional phonon model. We predict steady-state Seebeck and transient Peltier effects that await experimental discovery.

Transport phenomena in spin caloritronics.

The interconversion between spin, charge, and heat currents is being actively studied from the viewpoints of both fundamental physics and thermoelectric applications in the field of spin caloritronics. This field is a branch of spintronics, which has developed rapidly since the discovery of the thermo-spin conversion phenomenon called the spin Seebeck effect. In spin caloritronics, various thermo-spin conversion phenomena and principles have subsequently been discovered and magneto-thermoelectric effects, thermoelectric effects unique to magnetic materials, have received renewed attention with the advances in physical understanding and thermal/thermoelectric measurement techniques. However, the existence of various thermo-spin and magneto-thermoelectric conversion phenomena with similar names may confuse non-specialists. Thus, in this Review, the basic behaviors, spin-charge-heat current conversion symmetries, and functionalities of spin-caloritronic phenomena are summarized, which will help new entrants to learn fundamental physics, materials science, and application studies in spin caloritronics.

Simultaneous harvesting of radiative cooling and solar heating for transverse thermoelectric generation.

For any thermoelectric effects to be achieved, a thermoelectric material must have hot and cold sides. Typically, the hot side can be easily obtained by excess heat. However, the passive cooling method is often limited to convective heat transfer to the surroundings. Since thermoelectric voltage is proportional to the temperature difference between the hot and cold sides, efficient passive cooling to increase the temperature gradient is of critical importance. Here, we report simultaneous harvesting of radiative cooling at the top and solar heating at the bottom to enhance the temperature gradient for a transverse thermoelectric effect which generates thermoelectric voltage perpendicular to the temperature gradient. We demonstrate this concept by using the spin Seebeck effect and confirm that the spin Seebeck device shows the highest thermoelectric voltage when both radiative cooling and solar heating are utilized. Furthermore, the device generates thermoelectric voltage even at night through radiative cooling which enables continuous energy harvesting throughout a day. Planar geometry and scalable fabrication process are advantageous for energy harvesting applications.

Observation of the Magneto-Thomson Effect.

We report the observation of the higher-order thermoelectric conversion based on a magneto-Thomson effect. By means of thermoelectric imaging techniques, we directly observed the temperature change induced by the Thomson effect in a polycrystalline Bi_{88}Sb_{12} alloy under a magnetic field and found that the magnetically enhanced Thomson coefficient can be comparable to or even larger than the Seebeck coefficient. Our experiments reveal the significant contribution of the higher-order magnetothermoelectric conversion, opening the door to "nonlinear spin caloritronics."

Preservation of the nipple-areola complex in skin-sparing mastectomy for early breast cancer.

PURPOSE: Skin-sparing mastectomy (SSM) enables a radical cure of breast cancer while overcoming the cosmetic issues related to surgery. We review our experience of performing SSMs and assess whether preservation of the nipple-areola complex (NAC) could have been an option for some patients who underwent SSM. METHODS: The subjects of this retrospective study were women who underwent SSM that utilized four incision types; namely, the so-called tennis racket incision, a periareolar and midaxillary incision, an areola-sparing and midaxillary incision, and a small transverse elliptical incision. We assessed whether preservation of the NAC would have been an option in SSM, based on histologic examination of three serial cut surfaces of the specimen around the nipple, ruling out the option when evidence of the malignant lesion/s was found in at least one of the following locations: in the nipple, within a 1-cm radius from the base of the nipple, or within 1 cm from the surface of the NAC. RESULTS: We performed 193 SSMs. The cumulative 10-year local disease-free survival rate was 98%, with 89% of patients reporting levels of satisfaction with the reconstructed breast, of excellent, very good, or good. We evaluated that 70 of the 193 procedures could have been performed as nipple-sparing mastectomy (NSM). CONCLUSIONS: The outcomes of SSM in this series were excellent and NSM might have been an option for about one-third of the patients.

Deionization of Dopants in Silicon Nanofilms Even with Donor Concentration of Greater than 10(19) cm(-3).

Understanding the dopant properties in heavily doped nanoscale semiconductors is essential to design nanoscale devices. We report the deionization or finite ionization energy of dopants in silicon (Si) nanofilms with dopant concentration (ND) of greater than 10(19) cm(-3), which is in contrast to the zero ionization energy (ED) in bulk Si at the same ND. From the comparison of experimentally observed and theoretically calculated ED, we attribute the deionization to the suppression of metal-insulator transition in highly doped nanoscale semiconductors in addition to the quantum confinement and the dielectric mismatch, which greatly increase ED in low-doped nanoscale semiconductors. Thus, for nanoscale transistors, ND should be higher than that estimated from bulk Si dopant properties in order to reduce their resistivity by the metal-insulator transition.

Magnon Polarons in the Spin Seebeck Effect.

Sharp structures in the magnetic field-dependent spin Seebeck effect (SSE) voltages of Pt/Y_{3}Fe_{5}O_{12} at low temperatures are attributed to the magnon-phonon interaction. Experimental results are well reproduced by a Boltzmann theory that includes magnetoelastic coupling. The SSE anomalies coincide with magnetic fields tuned to the threshold of magnon-polaron formation. The effect gives insight into the relative quality of the lattice and magnetization dynamics.

Impact of physical activity on nonalcoholic steatohepatitis in people with nonalcoholic simple fatty liver: A prospective cohort study.

Preventing nonalcoholic simple fatty liver (NASFL) from progressing to nonalcoholic steatohepatitis (NASH) is a key to avoiding cirrhosis. Physical activity (PA) may help manage fatty liver; however, there is a lack of prospective studies showing an association between PA and NASH. Our current prospective study investigated whether PA prevents NASFL from progressing to NASH. Study data were obtained from the health check-up program of Meiji Yasuda Shinjuku Medical Center in Tokyo, Japan. From a baseline survey between 2005 and 2007, 1149 people with NASFL met eligibility criteria including low alcohol consumption. We followed participants until 2014 assessing liver status via ultrasound and liver enzyme levels, including alanine aminotransferase (ALT) and aspartate aminotransferase (AST). We classified participants with fatty liver and higher levels of either ALT or AST as having NASH. Through a self-reported questionnaire, we classified PA into three intensities: moderate low-intensity PA (MLPA, 3-5 METs), moderate high-intensity PA (MHPA, 5-7 METs), and vigorous-intensity PA (VPA, ≥7 METs). During a mean follow-up of 4.2years (4804person-years), 318 of the 1149 participants (27.7%) progressed from NASFL to NASH. A multivariate-adjusted Cox model showed a significant preventive effect of VPA on progression to NASH (HR=0.55, 95% CI=0.32-0.94) and no significant associations between MLPA (HR=1.01, 95% CI=0.79-1.30) or MHPA (HR=0.97, 95% CI=0.66-1.42) and progression to NASH. Only VPA prevented NASFL from progressing to NASH; MLPA and MHPA had no preventive effect on NASH. Higher intensity PA may be needed to manage NASH.

Modulation of thermoelectric power factor via radial dopant inhomogeneity in B-doped Si nanowires.

We demonstrate a modulation of thermoelectric power factor via a radial dopant inhomogeneity in B-doped Si nanowires. These nanowires grown via vapor-liquid-solid (VLS) method were naturally composed of a heavily doped outer shell layer and a lightly doped inner core. The thermopower measurements for a single nanowire demonstrated that the power factor values were higher than those of homogeneously B-doped Si nanowires. The field effect measurements revealed the enhancement of hole mobility for these VLS grown B-doped Si nanowires due to the modulation doping effect. This mobility enhancement increases overall electrical conductivity of nanowires without decreasing the Seebeck coefficient value, resulting in the increase of thermoelectric power factor. In addition, we found that tailoring the surface dopant distribution by introducing surface δ-doping can further increase the power factor value. Thus, intentionally tailoring radial dopant inhomogeneity promises a way to modulate the thermoelectric power factor of semiconductor nanowires.

Clinical relevance and low tumor-initiating properties of oligometastatic breast cancer in pulmonary metastasectomy.

Metastatic breast cancer is a systemic disease. However, certain subsets of patients, such as those with oligometastatic breast cancer (OMBC), have long-term survival prospects. Our aim was to evaluate the clinical relevance of OMBC in pulmonary metastasectomy of recurrent breast cancer. We also investigated lung metastases for the prevalence of CD44+/CD24-/low tumor cells and evaluated their prognostic significance. We reviewed data from a registry of breast cancer patients with lung metastases who underwent pulmonary metastasectomy at Jikei University Hospital. We analyzed prognostic factors for overall survival (OS) and progression-free survival (PFS) after metastasectomy and examined the prognostic difference between OMBC and non-OMBC patients. CD44+/CD24-/low tumor cells were detected by immunohistochemical analysis of lung metastases sites. Among 17 breast cancer patients with lung metastasis, 5-year OS and PFS rates were 72 and 36 %, respectively. Better OS was observed among patients with OMBC. Patients with OMBC, estrogen receptor-positive cells, and disease-free intervals of >8 years had better PFS. The presence of CD44+/CD24-/low tumor cells influenced progression after lung metastasectomy, with median PFS of only 6 months in patients with a high prevalence of cancer-initiating cells. CD44+/CD24-/low cells with cancer-initiating properties were present in only 9 % ± 3 of patients with OMBC, but were found in 73 % ± 12 of patients with non-OMBC. Pulmonary metastasectomy may be a treatment option for OMBC patients with lung metastases. Better prognosis of OMBC may be associated with low levels of cancer-initiating cells.

Clinical comparison of four types of skin incisions for skin-sparing mastectomy and immediate breast reconstruction.

PURPOSE: Skin-sparing mastectomy (SSM) and immediate breast reconstruction (IBR) has become popular as an effective procedure for patients with early breast cancer. We herein report an overview of the four types of skin incisions used for SSM. METHODS: The records of 111 consecutive breast cancer patients, who received SSM and IBR from 2003 to 2012, were reviewed retrospectively. Four types of skin incisions were used. Type A was the so-called tennis racquet incision, type B was a periareolar incision and mid-axillary incision, type C was the so-called areola-sparing with mid-axillary incision and type D was a small transverse elliptical incision and transverse axillary incision. RESULTS: Twenty-six type A, 59 type B, 20 type C and six type D incisions were made. The average blood loss and average length of the operation during SSM were not significantly different between the four approaches. The average areolar diameter was 35 mm for type A, B and D incisions, and 45 mm for type C. There was a need for postoperative nipple-areolar complex plasty (NAC-P) in 75 % of the cases following type A, B and D incisions, and 35 % of the cases treated using type C incisions. CONCLUSION: The type C incision is superior with regard to the cost and cosmetic outcomes, because fewer of these patients request postoperative NAC-P.

Detection of PPB-Level H2S Concentrations in Exhaled Breath Using Au Nanosheet Sensors with Small Variability, High Selectivity, and Long-Term Stability.

The continuous monitoring of hydrogen sulfide (H2S) in exhaled breath enables the detection of health issues such as halitosis and gastrointestinal problems. However, H2S sensors with high selectivity and parts per billion-level detection capability, which are essential for breath analysis, and facile fabrication processes for their integration with other devices are lacking. In this study, we demonstrated Au nanosheet H2S sensors with high selectivity, ppb-level detection capability, and high uniformity by optimizing their fabrication processes: (1) insertion of titanium nitride (TiN) as an adhesion layer to prevent Au agglomeration on the oxide substrate and (2) N2 annealing to improve nanosheet crystallinity. The fabricated Au nanosheets successfully detected H2S at concentrations as low as 5.6 ppb, and the estimated limit of detection was 0.5 ppb, which is superior to that of the human nose (8-13 ppb). In addition, the sensors detected H2S in the exhaled breath of simulated patients at concentrations as low as 175 ppb while showing high selectivity against interfering molecules, such as H2, alcohols, and humidity. Since Au nanosheets with uniform sensor characteristics enable easy device integration, the proposed sensor will be useful for facile health checkups based on breath analysis upon its integration into mobile devices.