I-V characteristics of single electron tunneling from symmetric and asymmetric double-barrier tunneling junctions

Copyright 2007 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Applied Physics Letters, 90(22), 223112, 2007 and may be found at http://dx.doi.org/10.1063/1.274525

Fabrication of nanoscale gaps using a combination of self-assembled molecular and electron beam lithographic techniques

Copyright 2006 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Applied Physics Letters, 88(22), 223111, 2006 and may be found at http://dx.doi.org/10.1063/1.220920

Reservoir Computing Approach to Robust Computation using Unreliable Nanoscale Networks

As we approach the physical limits of CMOS technology, advances in materials science and nanotechnology are making available a variety of unconventional computing substrates that can potentially replace top-down-designed silicon-based computing devices. Inherent stochasticity in the fabrication process and nanometer scale of these substrates inevitably lead to design variations, defects, faults, and noise in the resulting devices. A key challenge is how to harness such devices to perform robust computation. We propose reservoir computing as a solution. In reservoir computing, computation takes place by translating the dynamics of an excited medium, called a reservoir, into a desired output. This approach eliminates the need for external control and redundancy, and the programming is done using a closed-form regression problem on the output, which also allows concurrent programming using a single device. Using a theoretical model, we show that both regular and irregular reservoirs are intrinsically robust to structural noise as they perform computation

Nanoscale Electronic Inhomogeneity in In2Se3 Nanoribbons Revealed by Microwave Impedance Microscopy

Driven by interactions due to the charge, spin, orbital, and lattice degrees of freedom, nanoscale inhomogeneity has emerged as a new theme for materials with novel properties near multiphase boundaries. As vividly demonstrated in complex metal oxides and chalcogenides, these microscopic phases are of great scientific and technological importance for research in high-temperature superconductors, colossal magnetoresistance effect, phase-change memories, and domain switching operations. Direct imaging on dielectric properties of these local phases, however, presents a big challenge for existing scanning probe techniques. Here, we report the observation of electronic inhomogeneity in indium selenide (In2Se3) nanoribbons by near-field scanning microwave impedance microscopy. Multiple phases with local resistivity spanning six orders of magnitude are identified as the coexistence of superlattice, simple hexagonal lattice and amorphous structures with 100nm inhomogeneous length scale, consistent with high-resolution transmission electron microscope studies. The atomic-force-microscope-compatible microwave probe is able to perform quantitative sub-surface electronic study in a noninvasive manner. Finally, the phase change memory function in In2Se3 nanoribbon devices can be locally recorded with big signal of opposite signs.Comment: 11 pages, 4 figure

食塩過剰摂取防止に関する調理学的研究(第2報) : めん類の調理による食塩量の検討

"1)乾めんの食塩量は1.5～8.2%の間でかなり差がみられ,手打ちめんは機械打ちめんの約2倍量であった. 2)ゆでめんの食塩量は乾めんの約1/10となり,各めん間の食塩含有量の差は小さくなった.また,水さらし操作により,わずかながら食塩量は減少したが乾めん時に食塩量の多かっためんは水さらし後も他に比べて食塩量が多かった. 3)最終調理後の食塩量は,いずれのめんについても煮こみめんが最大で,次いでかけめん,つけめんで調理方法による影響が大きかった.すなわち,その食塩量は調味液の食塩量,調理時の温度および時間等に大きく影響を受けると考えられる. 4)めん料理において,めんのみ喫食する場合に比べ,汁もめんも全て喫食する場合に食塩摂取量は2～3倍に増大する.なお,本研究は日本家政学会第31回総会において発表した.終りに臨み,本研究にご協力いただきました伊藤博美・加藤紀子・木子あけみ.・小林恵子・吉川澄子諸氏に感謝いたします.

Quantum Conductance in Memristive Devices: Fundamentals, Developments, and Applications

Quantum effects in novel functional materials and new device concepts represent a potential breakthrough for the development of new information processing technologies based on quantum phenomena. Among the emerging technologies, memristive elements that exhibit resistive switching, which relies on the electrochemical formation/rupture of conductive nanofilaments, exhibit quantum conductance effects at room temperature. Despite the underlying resistive switching mechanism having been exploited for the realization of next-generation memories and neuromorphic computing architectures, the potentialities of quantum effects in memristive devices are still rather unexplored. Here, a comprehensive review on memristive quantum devices, where quantum conductance effects can be observed by coupling ionics with electronics, is presented. Fundamental electrochemical and physicochemical phenomena underlying device functionalities are introduced, together with fundamentals of electronic ballistic conduction transport in nanofilaments. Quantum conductance effects including quantum mode splitting, stability, and random telegraph noise are analyzed, reporting experimental techniques and challenges of nanoscale metrology for the characterization of memristive phenomena. Finally, potential applications and future perspectives are envisioned, discussing how memristive devices with controllable atomic-sized conductive filaments can represent not only suitable platforms for the investigation of quantum phenomena but also promising building blocks for the realization of integrated quantum systems working in air at room temperature.status: publishe

Multifunctionality of silver closo-boranes

Silver compounds share a rich history in technical applications including photography, catalysis, photocatalysis, cloud seeding and as antimicrobial agents. Here we present a class of silver compounds (Ag2B10H10 and Ag2B12H12) that are semiconductors with a bandgap at 2.3?eV in the green visible light spectrum. The silver boranes have extremely high ion conductivity and dynamic-anion facilitated Ag(+) migration is suggested based on the structural model. The ion conductivity is enhanced more than two orders of magnitude at room temperature (up to 3.2?mS?cm(-1)) by substitution with AgI to form new compounds. Furthermore, the closo-boranes show extremely fast silver nano-filament growth when excited by electrons during transmission electron microscope investigations. Ag nano-filaments can also be reabsorbed back into Ag2B12H12. These interesting properties demonstrate the multifunctionality of silver closo-boranes and open up avenues in a wide range of fields including photocatalysis, solid state ionics and nano-wire production

Mechanically-Controlled Binary Conductance Switching of a Single-Molecule Junction

Molecular-scale components are expected to be central to nanoscale electronic devices. While molecular-scale switching has been reported in atomic quantum point contacts, single-molecule junctions provide the additional flexibility of tuning the on/off conductance states through molecular design. Thus far, switching in single-molecule junctions has been attributed to changes in the conformation or charge state of the molecule. Here, we demonstrate reversible binary switching in a single-molecule junction by mechanical control of the metal-molecule contact geometry. We show that 4,4'-bipyridine-gold single-molecule junctions can be reversibly switched between two conductance states through repeated junction elongation and compression. Using first-principles calculations, we attribute the different measured conductance states to distinct contact geometries at the flexible but stable N-Au bond: conductance is low when the N-Au bond is perpendicular to the conducting pi-system, and high otherwise. This switching mechanism, inherent to the pyridine-gold link, could form the basis of a new class of mechanically-activated single-molecule switches

The correlation between colorectal cancer rates of proliferation and apoptosis and systemic cytokine levels; plus their influence upon survival

Colorectal cancer development is associated with a shift in host immunity with suppression of the cell-mediated immune system (CMI) and a predominance of humoral immunity (HI). Tumour progression is also associated with increased rates of cell proliferation and apoptosis. The aim of this study was to investigate whether these factors correlate and have an influence upon prognosis. Long-term follow-up was performed on 40 patients with colorectal cancer who had levels of tumour necrosis factor (TNF)-α, interferon (IFN)-γ and interleukin (IL)-10 measured from stimulated blood cultures before surgery. Their archived tumour specimens were analysed to determine a Ki-67-derived proliferation index (PI) and a M30-derived apoptosis index (AI). Tumour necrosis factor-α levels negatively correlated to tumour proliferation (ρ=−0.697, P=0.01). Interleukin-10 levels had a positive correlation with tumour proliferation (ρ=0.452, P=0.05) and apoptosis (ρ=0.587, P=0.01). Patient survival correlates to tumour pathological stage (P=0.0038) and vascular invasion (P=0.0014). An AI⩽0.6% and TNF-α levels ⩾8148 pg ml−1 correlate to improved survival (P=0.032, P=0.021). Tumour proliferation and apoptosis correlate to progressive suppression of the CMI-associated cytokine TNF-α and to and higher levels of IL-10. Survival is dependent upon the histological stage of the tumour, vascular invasion, rates of apoptosis and proliferation and systemic immunity which are all interconnected

Distinct and Overlapping Effector Functions of Expanded Human CD4+, CD8α+ and CD4-CD8α- Invariant Natural Killer T Cells

CD1d-restricted invariant natural killer T (iNKT) cells have diverse immune stimulatory/regulatory activities through their ability to release cytokines and to kill or transactivate other cells. Activation of iNKT cells can protect against multiple diseases in mice but clinical trials in humans have had limited impact. Clinical studies to date have targeted polyclonal mixtures of iNKT cells and we proposed that their subset compositions will influence therapeutic outcomes. We sorted and expanded iNKT cells from healthy donors and compared the phenotypes, cytotoxic activities and cytokine profiles of the CD4+, CD8α+ and CD4−CD8α− double-negative (DN) subsets. CD4+ iNKT cells expanded more readily than CD8α+ and DN iNKT cells upon mitogen stimulation. CD8α+ and DN iNKT cells most frequently expressed CD56, CD161 and NKG2D and most potently killed CD1d+ cell lines and primary leukemia cells. All iNKT subsets released Th1 (IFN-γ and TNF-α) and Th2 (IL-4, IL-5 and IL-13) cytokines. Relative amounts followed a CD8α>DN>CD4 pattern for Th1 and CD4>DN>CD8α for Th2. All iNKT subsets could simultaneously produce IFN-γ and IL-4, but single-positivity for IFN-γ or IL-4 was strikingly rare in CD4+ and CD8α+ fractions, respectively. Only CD4+ iNKT cells produced IL-9 and IL-10; DN cells released IL-17; and none produced IL-22. All iNKT subsets upregulated CD40L upon glycolipid stimulation and induced IL-10 and IL-12 secretion by dendritic cells. Thus, subset composition of iNKT cells is a major determinant of function. Use of enriched CD8α+, DN or CD4+ iNKT cells may optimally harness the immunoregulatory properties of iNKT cells for treatment of disease