The quality of strings for guitars: an experimental study

The object of the study was to correlate acoustical characteristics of a string (mainly sound levels and frequencies of the fundamental and overtones) to the subjective quality of “goodness”. A measuring set-up was built up for this purpose, and an experimental technique was developed. Twenty-four sets of strings from four different manufacturers were measured. At the same time, a simple psycho-acoustic test was conducted with thirty professional guitar players in order to test the reliability of the human judgement. The results show that the subjective evaluation of the “goodness” is quite reliable. Also, some relationships are found between sound levels of the fundamental and overtones, their frequencies and their spectral distribution and the mentioned “goodness”. More studies are required to validate the obtained results, and to relate other characteristics such as inharmonicity and decay-rate to the “goodness” of the string.     

Radiative transfer with anisotropic scattering in an isothermal slab

Two types of anisotropic scattering, linear anisotropic scattering and Rayleigh anisotropic scattering, are considered in the analysis of radiative transfer for an isothermal, plane-parallel medium confined between gray, diffuse walls. The problem is formulated in terms of a coupled pair of integral equations containing the intensity-moments as the unknown variables. These intensity-moments are shown to be the components of the source function. The set of equations is then solved both numerically and in closed form. The results reveal clearly the effects of anisotropic scattering on important characteristics such as heat flux directional emittance and incident radiant energy per unit area. These effects are well predicted by the approximate closed-form solution.     

Insight into the Structural Requirements of Protoporphyrino- gen Oxidase Inhibitors： Molecular Docking and CoMFA of Di- phenyl Ether, Isoxazole Phenyl, and Pyrazole Phenyl Ether

Protoporphyrinogen oxidase （PPO, EC 1.3.3.4） is one of the most significant targets for a large family of in- hibitors that may be used as herbicide, bactericide, fungicide, or photosensitizing activator to treat cancer through photodynamic therapy （PDT）. Molecular docking and CoMFA were combined in a multistep framework with the ultimate goal of identifying important factor contributing to the activity of PPO inhibitors. As a continuation of the previous research work on the development of new PPO inhibitors, the bioassay results indicated that good PPO in- hibitors were discovered in all of the three chemical series with ICs0 values ranging from 0.010 to 0.061 pmol·L ^-1. Using the crystal structure of tobacco mitochondrial PPO （mtPPO） as template, all the compounds were docked into the enzyme active site. The docking pose of each compound was subsequently used in a receptor-based alignment, leading to the development of a significant CoMFA model with r^2 value of 0.98 and q^2 （cross validation r^2） value of 0.63. This novel multistep framework gives insight into the and it can be extended to other classes of PPO inhibitors. In be particularly applicable in virtual screening procedures. structural characteristics for the binding of inhibitors, addition, the simplicity of the proposed approach may     

Nanoscopically resolved dynamic charge‐carrier distribution in operating interband cascade lasers

Dynamic charge carriers play a vital role in active photonic quantum/nanodevices, such as electrically pumped semiconductor lasers. Here we present a systematic experimental study of gain‐providing charge‐carrier distribution in a lasing interband cascade laser. The unique charge‐carrier distribution profile in the quantum‐well active region is quantitatively measured at nanometer scales by using a noninvasive scanning voltage microscopy technique. Experimental results clearly confirm the accumulation and spatial segregation of holes and electrons in the beating heart of the device. The measurement also shows that the charge‐carrier density is essentially clamped in the presence of stimulated emission at low temperatures. The threshold charge‐carrier density exhibits a linear but fairly weak temperature dependence, in contrast to the exponential temperature dependence of the threshold current. The experimental approach will lead to a deeper understanding of fundamental processes that govern the operation and performance of nanoelectronic devices, quantum devices and optoelectronic devices.

     

Preparation and crystal structure of binuclear chloro{6-[[chloro(triphenylphosphine)platinum](mesitylimino)methyl]pyridin-2-yl}bis(triphenylphosphine)platinum(II)

Treatment of N,N′-bis(mesityl)pyridine-2,6-carboxyimidoyl dichloride, 1, in toluene solution with [Pt(PPh₃)₄] at 100 °C afforded a novel platinacyclic compound, 3, in 63% yield, instead of the expected compound 2. The molecular and crystal structures of the title compound, 3, have been determined by the single crystal X-ray diffraction technique. The coordination geometries around the Pt atoms are distorted square-planar. In the crystal structure, the molecules are linked by a pair of C–H···N hydrogen bonds into a centrosymmetric dimer with an ring, centred at (1/2,1/2,1/2).     

Quadratic linear Keller maps of nilpotency index three

Let be a homogeneous polynomial map of degree d2 and a power linear map such that f and F_A are a generalized Gorni-Zampieri pair. We discuss the relation between the nilpotency indices of JH and J(Ay)^(d) and we show that f is linearly triangularizable if and only if F_A is linearly triangularizable. As a consequence, we show that a quadratic linear Keller map F_A=y+(Ay)⁽²⁾ with nilpotency index three, i.e., (J(Ay)⁽²⁾)³=0, is linearly triangularizable.     

A phenolic Schiff base for highly selective sensing of fluoride and cyanide via different channels

A chemosensor based on phenolic Schiff base bearing a pyrene group (sensor 1) has been synthesized and demonstrated. Sensor 1 showed a highly selective colorimetric response to fluoride anions based on a deprotonation process and fluorescent response to cyanide anions (606-fold fluorescence quantum yield enhancement) based on a cyclization process. Moreover, the cyclization of phenolic Schiff bases induced by cyanide could be used as a new way to synthesize 2-substituted benzoxazoles.     

Photocharacterization of Novel Ruthenium Dyes and Their Utilities as Oxygen Sensing Materials in Presence of Perfluorochemicals

Photophysical constants of three novel ruthenium dyes derived from tridentate pyridinediimine (pydim) ligands has been declared and their photoluminescent properties were investigated in solvents of dichloromethane (DCM), tetrahydrofuran (THF) and ethanol (EtOH) by UV-Visible absorption, emission and excitation spectra. The quantum yield, fluorescence decay time, molar extinction coefficient and Stoke’s shift values of the novel ruthenium complexes were determined. The perfluoro compound (PFC) nonadecafluorodecanoic acid which is also known as medical gas carrier has been used for the first time together with newly synthesized Ruthenium complexes in ethyl alcohol. The utilities of oxygen sensing materials were investigated in EtOH in presence of chemically and biochemically inert PFC.     

Mono-, and dibenzacridine imines. Synthesis of 1a,11b- dihydrobenz[c]azirino[α]acridine, 4b,5a-dihydrodibenz[c,h]- azirino[α]acridine and 1a,13b-dihydrodibenz[c,j]azirino[α]acridine

The syntheses of the K-imine derivatives of benz[c]acridine, dibenz[c,h]acridine and dibenz[a,h]acridine are described. The parent hydrocarbons 1, 6 and 11 were oxidized with sodium hypochlorite under phase transfer conditions to the corresponding K-oxides 4,9 and 14 , which in turn were reacted with sodium azide. The resulting azido alcohols were then cyclized with tributylphosphine to the title compounds 5,10 and 15.     

Mean-square torque of CO2 mixed with argon. interpretation in terms of intermolecular potentials

Spectral moments of CO₂ mixed with argon are measured for the v₃ vibration in the 5–300 bar range. The experimental values of the second moment are in excellent agreement with theory. The resulting mean-square torques are compared with those derived from potentials obtained with the electron gas model. One of these potentials is in satisfactory agreement with experiment.