Quantum wire network with magnetic flux

The charge transport and the noise of a quantum wire network, made of three semi-infinite external leads attached to a ring crossed by a magnetic flux, are investigated. The system is driven away from equilibrium by connecting the external leads to heat reservoirs with different temperatures and/or chemical potentials. The properties of the exact scattering matrix of this configuration as a function of the momentum, the magnetic flux and the transmission along the ring are explored. We derive the conductance and the noise, describing in detail the role of the magnetic flux. In the case of weak coupling between the ring and the reservoirs, a resonant tunneling effect is observed. We also discover that a non-zero magnetic flux has a strong impact on the usual Johnson–Nyquist law for the pure thermal noise at small temperatures.     

International nanotechnology development in 2003: Country,institution, and technology field analysis based on USPTO patent database

Nanoscale science and engineering (NSE) have seen rapid growth and expansion in new areas in recent years. This paper provides an international patent analysis using the U.S. Patent and Trademark Office (USPTO) data searched by keywords of the entire text: title, abstract, claims, and specifications. A fraction of these patents fully satisfy the National Nanotechnology Initiative definition of nanotechnology (which requires exploiting specific phenomena and direct manipulation at the nanoscale), while others only make use of NSE tools and methods of investigation. In previous work we proposed an integrated patent analysis and visualization framework of patent content mapping for the NSE field and of knowledge flow pattern identification until 2002. In this paper, the results are updated for 2003, and the new trends are presented.     

Connecting NSF funding to patent innovation in nanotechnology (2001–2004)

Nanotechnology research has experienced growth rapid in knowledge and innovations; it also attracted significant public funding in recent years. Several countries have recognized nanotechnology as a critical research domain that promises to revolutionize a wide range of fields of applications. In this paper, we present an analysis of the funding for nanoscale science and engineering (NSE) at the National Science Foundation (NSF) and its implications on technological innovation (number of patents) in this field from 2001 to 2004. Using a combination of basic bibliometric analysis and content visualization tools, we identify growth trends, research topic distribution, and the evolution in NSF funding and commercial patenting activities recorded at the United States Patent Office (USPTO). The patent citations are used to compare the impact of the NSF-funded research on nanotechnology development with research supported by other sources in the United States and abroad. The analysis shows that the NSF-funded researchers and patents authored by them have significantly higher impact based on patent citation measures in the four-year period than other comparison groups. The NSF-authored patent impact is growing faster with the lifetime of a patent, indicating the long-term importance of fundamental research.     

Lithium–sulfur redox: challenges and opportunities

Mechanistic and kinetic insights into the lithium–sulfur (Li–S) redox processes are essential to fundamentally increase the utilization of active material and further realize the practical applications of Li–S batteries. In this article, recent advances of in situ/operando characterizations of Li–S reaction processes and mechanism are presented, revealing the multistep transformations of S species. Interfacial visualization, from the whole interface to nanometer scale, provides specific evidence of sulfur distribution, polysulfide diffusion, and lithium sulfide precipitation. Moreover, the development of efficient electrocatalysts to improve the reaction kinetics are additionally presented and discussed. Although the understanding of the mechanism of the Li–S redox processes has improved in recent times, additional efforts are required for the scale-up production and practical applications of Li–S batteries.     

Torsion-complete and algebraically compact groups with compact endomorphism rings

We give a complete characterization of torsion-complete and algebraically compact abelian groups whose endomorphism rings admit a compact ring topology.     

Surface morphology and amide concentration depth profile of aminolyzed poly(ethylene terephthalate) films

Surface of biaxially oriented poly(ethylene terephthalate) films was chemically modified by exposure to ethylenediamine (EDA), triethylenetetramine (TETA), and tetraethylenepentamine (TEPA) for different treatment times. Variable angle attenuated total reflection Fourier transform infrared (ATR‐FTIR) spectroscopy was used in conjunction with weight loss measurements, scanning electron microscopy (SEM), and atomic force microscopy to establish the surface modification and to draw the depth profile of the newly created species, with emphasis on amide group. A clear differentiation was found between the effects of the three amines studied: EDA produces the highest amidation degree but, because of its deep penetration into the film, leads to delamination of rather thick layers, TETA reacts at and near surface and develops surface cracks without delamination, and TEPA is the mildest reactant, generating amide groups on the surface without visible deterioration of the sample. It was proved that the amide II absorption band became weaker with increasing analyzed depth, with a pronounced heterogeneity near the surface. SEM micrographs showed the development of cracks onto the surface at longer aminolysis time, which allowed a better understanding of ATR‐FTIR observations. Assuming an exponential decay for the depth profile spectrally obtained, the surface concentration of amide groups and the decay constant were determined for the amines and reaction times used. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Synthesis of Some Flame-Retardants Containing Phosphorus and Halogen

Polyphosphonates, one of the longest known classes of organophosphonic compounds, are of interest because they can confer low flammability, plasticity, thermal stability, and lubrication properties on polymers.     

Cherenkov Radiation in Moving Medium

Cherenkov radiation in uniformly moving homogeneous isotropic medium without dispersion is studied. Formula for the spectrum of Cherenkov radiation of fermion was derived for the case when the speed of the medium is less than the speed of light in this medium at rest. The properties of Cherenkov spectrum are investigated.     

Stability constants of complexes formed by new Schiff-base lariat ethers derived from 4,13-diaza-18-crown-6 with Ag+, Pb2+, Cu2+ cations determined by competitive potentiometry

The stability of complexes formed by a series of Schiff-base lariat ethers, derived from 4,13-diaza-18-crown-6, 1 with Ag⁺, Pb²⁺, Cu²⁺ cations, has been comparatively determined, in methanol: dichloromethane solution. We present here the synthesis and an interesting competitive potentiometry method useful for the stability constant determination for a new family of Schiff-base bibracchial lariat ethers. The stability constants and the selectivity in competitive complexation of Ag⁺, Pb²⁺ and Cu²⁺ cations by macrocyclic receptors 1–7 (L), can be accurately evaluated and species distribution diagrams can be calculated for individual system. In all cases further functionalization of bibracchial lariat ethers 2–7 is accompanied by an increasing of the selectivity, relative to the complexes of the initial 4,13-diaza-18-crown-6 macrocycle 1.