The electrostatics of Einstein’s unified field theory

When sources are added at their right-hand sides, and g_(ik) is a priori assumed to be the metric, the equations of Einstein’s Hermitian theory of relativity were shown to allow for an exact solution that describes the general electrostatic field of n point charges. Moreover, the injunction of spherical symmetry of g_(ik) in the infinitesimal neighbourhood of each of the charges was proved to yield the equilibrium conditions of the n charges in keeping with ordinary electrostatics. The tensor g_(ik), however, cannot be the metric of the theory, since it enters neither the eikonal equation nor the equation of motion of uncharged test particles. A physically correct metric that rules both the behaviour of wave fronts and of uncharged matter is the one indicated by Hély.In the present paper it is shown how the electrostatic solution predicts the structure of the n charged particles and their mutual positions of electrostatic equilibrium when Hély’s physically correct metric is adopted.     

Unexpected density fluctuations in jammed disordered sphere packings

We computationally study jammed disordered hard-sphere packings as large as a million particles. We show that the packings are saturated and hyperuniform, i.e., that local density fluctuations grow only as a logarithmically augmented surface area rather than the volume of the window. The structure factor shows an unusual nonanalytic linear dependence near the origin, S(k) approximately |k|. In addition to exponentially damped oscillations seen in liquids, this implies a weak power-law tail in the total correlation function, h(r) approximately -r(-4), and a long-ranged direct correlation function c(r).     

A novel and highly efficient synthetic route to unsymmetrical organoselenides using cesium bases

A new and convenient one-pot method for the preparation of unsymmetrical selenides has been developed. In the presence of cesium hydroxide, molecular sieves, and DMF, benzeneselenol undergoes direct alkylation with various alkyl halides for the synthesis of alkyl phenyl selenides in moderate to excellent yields. Another method to prepare unsymmetrical organoselenides was also completed by coupling terminal alkynes with benzeneselenyl bromide. As an application, the synthesis of a selenopeptide was also accomplished. Furthermore, this methodology was extended to the synthesis of an organoselenide on solid support.     

Determination of creatinine in human serum by short-end injection capillary zone electrophoresis

A new ultra-rapid free-solution capillary zone electrophoresis method to measure serum creatinine is presented. Procedural parameters such as injection mode, concentration and pH of phosphate running buffer and acidic deproteinization of serum samples were investigated. Short-end injection permits a decrease of the analysis time by injecting samples at the outlet end of a silica capillary closest to the detection window, so reducing the migration distance. Thus, when a capillary with an effective length of 10.2 cm and a 40 mmol/L sodium phosphate buffer pH 2.35 was used, the obtained migration time of the creatinine peak was the shortest never described before, about 1.1 min. These conditions give a good reproducibility of the migration times (coefficient of variation, CV% < 0.5) and the peak areas (CV% < 2.8). Intra- and interassay CV were 3.06 and 6.26%, respectively, and analytical recovery was 99.4%. We compared our proposed method to Jaffé colorimetric assay, by measuring serum creatinine in 128 normal subjects. The obtained data were analyzed by the Passing and Bablok regression and Bland-Altman test. Creatinine concentration in healthy subjects was also used to investigate on its relationships with plasma thiols levels.     

Molecular organization and syn ? anti conformational equilibria in ethane-bridged bis(zinc porphyrin) floating films at the air-water interface

The behavior of the symmetrical ethane-bridged bis(Zn porphyrin) (1) has been investigated at the air-water interface. The molecular organization of floating films of pure 1 and its mixture with amphiphilic substances, such as arachidic acid and n-octadecylamine, was inspected by means of surface pressure-area isotherms, Brewster angle microscopy and reflection spectroscopy in the UV-Vis region. The overall results suggest the presence in all cases of mainly the anti conformer of 1 even when the dimer was spread on pure water, through the ligation of water molecules to the zinc atoms in the axial positions. It was also demonstrated for the first time that the syn-to-anti conformational transition of the porphyrin dimer can be accelerated by the ligation of suitable amphiphiles even at the liquid-air interface. In particular, it is noted that n-octadecylamine, and arachidic acid (to a lesser extent), added to the system as amphiphiles, drive the syn ? anti equilibrium of 1 towards the anti form through the axial ligation of the amino or carboxylate group to the zinc atoms.     

Optimization of high-order harmonic generation by adaptive control of a sub-10-fs pulse wave front

We present a method for the optimization of high-order harmonic generation based on wave-front correction of the driving laser beam. The technique exploits wave-front adaptive control by means of a deformable mirror, governed by an optimization procedure.     

Evaluation of teicoplanin chiral stationary phases of 3.5 and 5 microm inside diameter silica microparticles by polar-organic mode capillary electrochromatography

Different types of fused-silica capillaries of 75 microm inside diameter (ID) were packed, namely type A and B, and evaluated for the direct resolution of racemates of several basic compounds by enantioselective capillary electrochromatography (e-CEC). Type A was packed with a chiral stationary phase (CSP) containing teicoplanin (TE) mixed with silica microparticles (3:1 w/w) while type B contained only the TE-CSP. In both cases, particles of different sizes (3.5 and 5 microm ID) were employed. A polar-organic mobile phase containing methanol-acetonitrile (60-40% v/v and 0.05% w/v ammonium acetate was used. Several beta-blockers (alprenolol, oxprenolol, metoprolol, pindolol, salbutamol, propranolol, atenolol, acebutolol) were baseline-enantioresolved with both capillary types, in very short times.     

Reversible light-driven redox switching of multifunctional dipolar ruthenium(III/II) pentaammine(4,4'-bipyridinium) complexes

We report the first example of a molecular switch of multifunctional dipolar ruthenium(III/II) pentaammine-N-methyl-(4,4'-bipyridinium) complexes, exclusively driven by light. This is achieved by using a two-phase (water/benzene) system in which RuIII/II complexes are soluble only in the water phase. The reversible redox switching is triggered by the selective irradiation of the water and the benzene compartments with 254 and 528 nm light, respectively.