High-Mobility p-Type and n-Type Copper Nitride Semiconductors by Direct Nitriding Synthesis and In Silico Doping Design.

Thin-film photovoltaics (PV) have emerged as a technology that can meet the growing demands for efficient and low-cost large-scale cells. However, the photoabsorbers currently in use contain expensive or toxic elements, and the difficulty in bipolar doping, particularly in a device structure, requires elaborate optimization of the heterostructures for improving the efficiency. This study shows that bipolar doping with high hole and electron mobilities in copper nitride (Cu N), composed solely of earth-abundant and environmentally benign elements, is readily available through a novel gaseous direct nitriding reaction applicable to uniform and large-area deposition.

Three-input gate logic circuits on chemically assembled single-electron transistors with organic and inorganic hybrid passivation layers.

Single-electron transistors (SETs) are sub-10-nm scale electronic devices based on conductive Coulomb islands sandwiched between double-barrier tunneling barriers. Chemically assembled SETs with alkanethiol-protected Au nanoparticles show highly stable Coulomb diamonds and two-input logic operations. The combination of bottom-up and top-down processes used to form the passivation layer is vital for realizing multi-gate chemically assembled SET circuits, as this combination enables us to connect conventional complementary metal oxide semiconductor (CMOS) technologies via planar processes.

Strong evidence for d-electron spin transport at room temperature at a LaAlO/SrTiO interface.

A d-orbital electron has an anisotropic electron orbital and is a source of magnetism. The realization of a two-dimensional electron gas (2DEG) embedded at a LaAlO/SrTiO interface surprised researchers in materials and physical sciences because the 2DEG consists of 3d-electrons of Ti with extraordinarily large carrier mobility, even in the insulating oxide heterostructure. To date, a wide variety of physical phenomena, such as ferromagnetism and the quantum Hall effect, have been discovered in this 2DEG system, demonstrating the ability of d-electron 2DEG systems to provide a material platform for the study of interesting physics.

Polar Spinel-Perovskite Interfaces: an atomistic study of Fe3O4(111)/SrTiO3(111) structure and functionality.

Atomic resolution scanning transmission electron microscopy and electron energy loss spectroscopy combined with ab initio electronic calculations are used to determine the structure and properties of the Fe3O4(111)/SrTiO3(111) polar interface. The interfacial structure and chemical composition are shown to be atomically sharp and of an octahedral Fe/SrO3 nature. Band alignment across the interface pins the Fermi level in the vicinity of the conduction band of SrTiO3.

Atomic and electronic structure of twin growth defects in magnetite.

We report the existence of a stable twin defect in Fe3O4 thin films. By using aberration corrected scanning transmission electron microscopy and spectroscopy the atomic structure of the twin boundary has been determined. The boundary is confined to the (111) growth plane and it is non-stoichiometric due to a missing Fe octahedral plane.

New functionalities in abundant element oxides: ubiquitous element strategy.

While most ceramics are composed of ubiquitous elements (the ten most abundant elements within the Earth's crust), many advanced materials are based on rare elements. A 'rare-element crisis' is approaching owing to the imbalance between the limited supply of rare elements and the increasing demand. Therefore, we propose a 'ubiquitous element strategy' for materials research, which aims to apply abundant elements in a variety of innovative applications.

Two-dimensional confinement of 3d{1} electrons in LaTiO_{3}/LaAlO{3} multilayers.

We report spectroscopic ellipsometry measurements of the anisotropy of the interband transitions parallel and perpendicular to the planes of (LaTiO3)n(LaAlO3)5 multilayers with n=1-3. These provide direct information about the electronic structure of the two-dimensional (2D) 3d{1} state of the Ti ions. In combination with local density approximation, including a Hubbard U calculation, we suggest that 2D confinement in the TiO2 slabs lifts the degeneracy of the t{2g} states leaving only the planar d{xy} orbitals occupied.

Spectroscopic evidence for competing reconstructions in polar multilayers LaAlO3/LaVO3/LaAlO3.

We have studied the valence redistribution of V in LaAlO(3)/LaVO(3)/LaAlO(3) trilayers, which are composed of only polar layers grown on SrTiO3 (001) substrates, by core-level photoemission spectroscopy. We have found that the V valence is intermediate between V3+ and V4+ for thin LaAlO3 cap layers, decreases with increasing cap-layer thickness, and finally recovers the bulk value of V3+ at approximately 10 unit-cell thickness. In order to interpret these results, we propose that the atomic reconstruction of the polar LaAlO3 surface competes with the purely electronic V valence change so that the polar catastrophe is avoided at the cost of minimum energy.

Vanishing hall coefficient in the extreme quantum limit in photocarrier-doped SrTiO3.

We explore the extreme quantum limit of photogenerated electrons in quantum paraelectric SrTiO3. This regime is distinct from conventional semiconductors, due to the large electron effective mass and large dielectric constant. At low temperature, the magnetoresistance and Hall resistivity saturate at a high magnetic field, deviating from conventional behavior.

Epidemiologic and clinical survey of victims of centipede stings admitted to Hospital Vital Brazil (São Paulo, Brazil).

We retrospectively analyzed 98 proven cases of centipede stings admitted to Hospital Vital Brazil, Butantan Institute, São Paulo, Brazil, between 1990 and 2007. Most stings occurred at the metropolitan area of São Paulo city (n=94, 95.9%), in the domiciles of patients (n=67, 68.

Polar discontinuity doping of the LaVO_{3}/SrTiO_{3} interface.

We have investigated the transport properties of LaVO_{3}/SrTiO_{3} Mott-insulator-band-insulator heterointerfaces for various configurations. The (001)-oriented n-type VO_{2}/LaO/TiO_{2} polar discontinuity is conducting, exhibiting a LaVO3 thickness-dependent metal-insulator transition and low temperature anomalous Hall effect. The (001) p-type VO_{2}/SrO/TiO_{2} interface, formed by inserting a single layer of bulk metallic SrVO3 or SrO, drives the interface insulating.

Nanometer scale electronic reconstruction at the interface between LaVO3 and LaVO4.

Electrons at interfaces, driven to minimize their free energy, are distributed differently than in bulk. This can be dramatic at interfaces involving heterovalent compounds. Here we profile an abrupt interface between V 3d2 LaVO3 and V 3d0 LaVO4 using electron energy loss spectroscopy.

Narrow photoemission peak at the Fermi level in Fe/Cu(111).

We have studied electronic states of Fe adatoms deposited on Cu(111) by photoemission spectroscopy and have found a narrow peak at the Fermi level in the Fe 3d spectral function. The Fe 3d spectral function would be consistent with the Anderson impurity model, which has been widely used for the interpretation of bulk Ce and Yb compounds. This result indicates a strong reduction of hybridization between the Fe 3d state and the conduction-band states and an enhancement of effective Coulomb interaction for the Fe 3d electrons in an Fe adatom on Cu(111).

Muscle oxygenation trends during constant work rate cycle exercise in men and women.

Purpose: To examine the relationship between muscle oxygenation and arteriovenous oxygen difference [(a - v)O2diff)] at four constant rate workloads in healthy men and women and to compare these responses between the genders.

Methods: Nineteen men and 14 women consented to perform an incremental test to identify the lactic acidosis threshold (LAT) and maximal aerobic power (VO2max) and an intermittent constant work rate test at an oxygen uptake corresponding to 40% LAT, 80% LAT, 25% LAT-VO2max, and 50% LAT-VO2max. Each exercise interval was 5 min long followed by 2 min of recovery.

Detection of ventilatory threshold using near infrared spectroscopy in men and women.

The onset of anaerobic (lactate) metabolism during incremental exercise, which may be a result of an imbalance between tissue oxygen supply and demand, has been associated with the gas exchange ventilatory threshold (VT). This study was designed to examine whether near infrared spectroscopy (NIRS) could be used to detect the VT in healthy subjects. Twenty-one men and 19 women completed incremental cycle ergometry during which NIRS measurements were obtained from the right vastus lateralis and gas exchange measurements were monitored simultaneously using a metabolic cart.

Effect of electro-motor stimulation on the power production of a maximally stretched muscle.

Unlabelled: The effect of electro-motor stimulation (EMS) upon the increase in power production of the tibialis anterior muscle (TA) of healthy individuals in both the maximally stretched (ST group) and shortened (SH group) positions was investigated. The effect of cross-education upon the contralateral muscle was also examined. EMS with a frequency of 50 hertz, a duration of 0.