Solution-processed organic spin-charge converter

Conjugated polymers and small organic molecules are enabling new, flexible, large-area, low-cost optoelectronic devices, such as organic light-emitting diodes, transistors and solar cells. Owing to their exceptionally long spin lifetimes, these carbon-based materials could also have an important impact on spintronics, where carrier spins play a key role in transmitting, processing and storing information. However, to exploit this potential, a method for direct conversion of spin information into an electric signal is indispensable. Here we show that a pure spin current can be produced in a solution-processed conducting polymer by pumping spins through a ferromagnetic resonance in an adjacent magnetic insulator, and that this generates an electric voltage across the polymer film. We demonstrate that the experimental characteristics of the generated voltage are consistent with it being generated through an inverse spin Hall effect in the conducting polymer. In contrast with inorganic materials, the conducting polymer exhibits coexistence of high spin-current to charge-current conversion efficiency and long spin lifetimes. Our discovery opens a route for a new generation of molecular-structure-engineered spintronic devices, which could lead to important advances in plastic spintronics.

Spin-pump-induced spin transport in p-type Si at room temperature

A spin battery concept is applied for the dynamical generation of pure spin current and spin transport in p-type silicon (p-Si). Ferromagnetic resonance and effective s-d coupling in Ni(80)Fe(20) results in spin accumulation at the Ni(80)Fe(20)/p-Si interface, inducing spin injection and the generation of spin current in the p-Si. The pure spin current is converted to a charge current by the inverse spin Hall effect of Pd evaporated onto the p-Si. This approach demonstrates the generation and transport of pure spin current in p-Si at room temperature.

Spin pumping driven by bistable exchange spin waves

Spin pumping driven by bistable exchange spin waves is demonstrated in a Pt/Y3Fe5O12 film under parametric excitation. In the Pt/Y3Fe5O12 film, the spin pumping driven by parametric excitation selectively enhances the relaxation of short-wavelength exchange spin waves, indicating strong coupling between the exchange spin waves and spin currents at the interface through efficient spin transfer. The parametric spin pumping, furthermore, allows direct access to nonlinear spin wave dynamics in combination with the inverse spin Hall effect, revealing unconventional bistability of the exchange spin waves.

Observation of the inverse spin Hall effect in silicon

The spin–orbit interaction in a solid couples the spin of an electron to its momentum. This coupling gives rise to mutual conversion between spin and charge currents: the direct and inverse spin Hall effects. The spin Hall effects have been observed in metals and semiconductors. However, the spin/charge conversion has not been realized in one of the most fundamental semiconductors, silicon, where accessing the spin Hall effects has been believed to be difficult because of its very weak spin–orbit interaction. Here we report observation of the inverse spin Hall effect in silicon at room temperature. The spin/charge current conversion efficiency, the spin Hall angle, is obtained as 0.0001 for a p-type silicon film. In spite of the small spin Hall angle, we found a clear electric voltage due to the inverse spin Hall effect in the p-Si film, demonstrating that silicon can be used as a spin-current detector.

The spin Hall effect is a spin current induced by an electric current, and its occurrence in semiconductors is a promising route to controlling spins and their transport. Here, the inverse spin Hall effect, in which an electric current is induced by a spin current, is observed in silicon for the first time.

Dietary intake of vitamin B12 and folic acid is associated with lower blood pressure in Japanese preschool children

BACKGROUND

An elevated plasma homocysteine level is an independent risk factor for high blood pressure and cardiovascular disease, and its level is regulated by three vitamins; vitamin B6, B12, and folic acid. Until now, the association between the intake of these vitamins and blood pressure has been examined only in adult populations. We purposed to examine the association between dietary intake of these three vitamins and blood pressure of young children.

METHODS

We conducted a cross-sectional study at Japanese preschools in 2006. Blood pressure was measured among 418 children aged 3-6 years. Diets including vitamins were assessed by a 3-day dietary record. We compared the blood pressure levels among the four groups defined according to quartile of energy-adjusted vitamin intake by using analysis of covariance after controlling for age, sex, and body mass index.

RESULTS

The mean systolic blood pressure was 6.6 mm Hg lower and the mean diastolic blood pressure was 5.7 mm Hg lower in the highest quartile than in the lowest quartile of vitamin B12 intake (P for trend was <0.001 and 0.006, respectively). The mean systolic blood pressure was 4.1 mm Hg lower in the highest quartile than in the lowest quartile of folic acid intake (P for trend = 0.004). Vitamin B6 intake was not significantly associated with blood pressure.

CONCLUSIONS

The data suggest that high intakes of folic acid and vitamin B12 are associated with lower levels of blood pressure among preschool children.

The diagnostic accuracy of high-resolution endoscopy, autofluorescence imaging and narrow-band imaging for differentially diagnosing colon adenoma

BACKGROUND AND STUDY AIMS

Conventional colonoscopy can result in unnecessary biopsy or endoscopic resection due to its inability to distinguish adenomas from hyperplastic polyps. This study therefore evaluated the efficacy of high-resolution endoscopy (HRE), autofluorescence imaging (AFI), and narrow-band imaging (NBI) in discriminating colon adenoma from hyperplastic polyps.

PATIENTS AND METHODS

This was a prospective multicenter study in patients undergoing AFI and NBI examinations. HRE, AFI, and NBI images were classified into two groups based on morphological characteristics, the predominant color intensities, and the visibility of meshed capillary vessels, respectively. Each of the endoscopic photographs were independently evaluated by a single endoscopist. The images were then assessed by three specialists and three residents, the latter having performed < 500 colonoscopies and < 30 NBI and AFI examinations. Diagnostic test statistics were calculated to compare the accuracy in differentiating colon adenoma from hyperplastic polyps for each method.

RESULTS

A total of 183 patients were enrolled in the study and 339 adenomas and 85 hyperplastic polyps were identified. AFI and NBI could distinguish adenoma from hyperplastic polyps with an accuracy of 84.9 % and 88.4 %, respectively, whereas HRE exhibited an accuracy of 75.9 %. In the 358 lesions in which the AFI diagnosis was consistent with that of NBI, the accuracy, sensitivity, and specificity were high, at 91.9 %, 92.7 %, and 92.9 %, respectively. During the study comparing specialists and residents, AFI and NBI dramatically improved the diagnostic accuracy of residents from 69.1 % to 86.1 % and 84.7 %, respectively.

CONCLUSIONS

Both AFI and NBI are considered to be feasible tools that can discriminate colon adenoma from hyperplastic polyps, and their use may be particularly beneficial for less-experienced endoscopists.

Superelastic effect in polycrystalline ferrous alloys

In superelastic alloys, large deformation can revert to a memorized shape after removing the stress. However, the stress increases with increasing temperature, which limits the practical use over a wide temperature range. Polycrystalline Fe-Mn-Al-Ni shape memory alloys show a small temperature dependence of the superelastic stress because of a small transformation entropy change brought about by a magnetic contribution to the Gibbs energies. For one alloy composition, the superelastic stress varies by 0.53 megapascal/°C over a temperature range from -196 to 240°C.

Relationship of intake of plant-based foods with 6-n-propylthiouracil sensitivity and food neophobia in Japanese preschool children

BACKGROUND/OBJECTIVES

Diets rich in plant-based foods such as vegetables, fruits and soy foods have been suggested to have beneficial effects on health. However, phytochemicals contained in plant-based foods are generally bitter and acrid. We investigated whether intake of vegetables, fruits and soy foods is associated with sensitivity to bitterness and reluctance to eat new foods (food neophobia) in Japanese preschool children.

SUBJECTS/METHODS

Subjects of this cross-sectional study were healthy Japanese, 167 boys and 156 girls, aged 4-6 years. Intake of vegetables, fruits and soy foods was estimated from 3-day dietary records. Subjects were classified as either tasters or non-tasters of 6-n-propylthiouracil (PROP) based on their ability to taste 0.56 mmol/l PROP. Information on each child's age, height, weight, food neophobia status and food variety, as well as maternal diet and parental control over the child's eating, was obtained by a parent-administered questionnaire. Food neophobia was assessed using the Child Food Neophobia Scale (CFNS).

RESULTS

A high intake of vegetables was significantly associated with a low CFNS score in boys after controlling for covariates (P=0.0008). Among the boys, soy food intake was significantly higher in PROP non-tasters than in tasters, except those with low CFNS scores (P=0.0019). High intake of soy foods was significantly associated with a low neophobia score in PROP tasters but not in non-tasters (P=0.0024).

CONCLUSIONS

These data suggest that sensitivity to bitter taste and food neophobia may influence the consumption of vegetables and soy foods among Japanese preschool boys.