Transport through a double barrier in Large Radius Carbon Nanotubes with a transverse magnetic field

We discuss the Luttinger Liquid behaviour of Large Radius Carbon Nanotube e.g. the Multi Wall ones (MWNT), under the action of a transverse magnetic field B. Our results imply a reduction with B in the value of the bulk critical exponent, α_bulk, for the tunneling density of states, which is in agreement with that observed in transport experiments. Then, the problem of transport through a Quantum Dot formed by two intramolecular tunneling barriers along the MWNT, weakly coupled to Tomonaga-Luttinger liquids is studied, including the action of a strong transverse magnetic field B. We predict the presence of some peaks in the conductance G versus B, related to the magnetic flux quantization in the ballistic regime, at a very low temperature T, and also at higher values of T, where the Luttinger behaviour dominates. The temperature dependence of the maximum G_max of the conductance peak according to the Sequential Tunneling follows a power law, G ∝T^γe-1 with γ_e linearly dependent on the critical exponent, α_end, strongly reduced by B.     

Methanol Mitigation during Manufacturing of Fruit Spirits with Special Consideration of Novel Coffee Cherry Spirits

Methanol is a natural ingredient with major occurrence in fruit spirits, such as apple, pear, plum or cherry spirits, but also in spirits made from coffee pulp. The compound is formed during fermentation and the following mash storage by enzymatic hydrolysis of naturally present pectins. Methanol is toxic above certain threshold levels and legal limits have been set in most jurisdictions. Therefore, the methanol content needs to be mitigated and its level must be controlled. This article will review the several factors that influence the methanol content including the pH value of the mash, the addition of various yeast and enzyme preparations, fermentation temperature, mash storage, and most importantly the raw material quality and hygiene. From all these mitigation possibilities, lowering the pH value and the use of cultured yeasts when mashing fruit substances is already common as best practice today. Also a controlled yeast fermentation at acidic pH facilitates not only reduced methanol formation, but ultimately also leads to quality benefits of the distillate. Special care has to be observed in the case of spirits made from coffee by-products which are prone to spoilage with very high methanol contents reported in past studies.     

Nanojunctions as logic operators for the spintronics

We propose two all-electrical nanodevices where the spin properties of an incoming electron are modified by the spin-orbit interaction (SOI), resulting in a transformation of the qubit state carried by the spin. Our proposal is essentially based on nanojunctions made of crossing quantum wires patterned in a two dimensional electron gas where the Rashba SOI is present. We investigate in detail the spin precession of one electron traveling in the proposed nanodevices. The nanojunctions acts as spin filters or ballistic spin rotators whose properties can be varied by tuning the strength of the SOI, by changing the geometry of the junctions. Two different basic mechanism in order to obtain in plane or out of the plane rotations are discussed. We show that, starting from the spin rotators, a large class of unitary transformations can be attained with one or more nanojunctions in series. By choosing appropriate parameters the spin transformations can be made unitary, which corresponds to lossless operators.     

Impedance spectroscopy of reactive polymers. 4. An improved experimental procedure for measurement of effective resistivity

Impedance spectroscopy of reactive systems, polymer-forming and non-polymer-forming alike, has been under active investigation in our laboratory for several years. In this article we describe an improved experimental procedure for the determination of fundamental dielectric properties during reaction. A series of experimental steps was established and is recommended in order to generate reproducible and reliable results. © 1996 John Wiley & Sons, Inc.     

Supersymmetry in Anti-de Sitter Space

We review the renormalization of the ground state solution of extended supergravity and super-symmetric Kaluza-Klein theories. The computation of an adiabatic expansion of the effective action to the one-loop order yields the result that a linear superfield insertion in the superpotential is needed, in order to renormalize the nonvanishing one-particle-irreducible one-point functions, whereas supersymmetry is preserved at each extremum of the effective potential. The calculation of the one-particle-irreducible two-and three-point functions shows that neither the mass nor the interaction lagrangians get renormalized to the one-loop order. We conclude that the one-loop effects proportional to the contraction parameter of the curved background space force a violation of the no-renormalization theorem.     

Biexcitons in artificial molecules with in-plane magnetic field

We theoretically investigate the effect of a magnetic field perpendicular to the tunneling direction on the ground-state properties of biexcitons in coupled quantum dots. The single-particle states are computed by numerically solving the 3D Scrödinger equation. The biexciton states are obtained by means of a configuration-interaction approach, which fully accounts for the intra- and inter-dot Coulomb correlations. We show that the biexciton ground state undergoes non-trivial transitions as a function of the applied magnetic field, which can be traced back to unexpected carrier localizations.     

Higher derivative modifications ofD=10 superspace Yang-Mills theories

We extend the superspace treatment of higher derivative supersymmetric Yang-Mills theories, emphasizing the role played by manifestD=10 Lorentz covariance and supersymmetry invariance. As an example, the superspace formulation of the effective action is considered for the massless fields in the open superstring, as well as in theSO(32) andE ₈×E₈ superstring theories. We show that there exists a unique modification of thef-tensor supercurrent which can provide the embedding of theO(α'³) string corrections in the slope parameter expansion for the Yang-Mills sector inD=10 superspace. The new correction term is relevant for the understanding of nonperturbative effects.     

Covalent decoration of multi-walled carbon nanotubes with silica nanoparticles

We describe a novel tunable approach for the synthesis of carbon nanotube-silica nanobead composites. The control of nanotube morphology and bead size coupled with the versatility of silica chemistry makes these structures an excellent platform for the development of biosensors, or for optical, magnetic and catalytic applications.