Hydrodynamic Characterization of a Column-type Prototype Bioreactor

Agro-food industrial processes produce a large amount of residues, most of which are organic. One of the possible solutions for the treatment of these residues is anaerobic digestion in bioreactors. A novel 18-L bioreactor for treating waste water was designed based on pneumatic agitation and semispherical baffles. Flow patterns were visualized using the particle tracer technique. Circulation times were measured with the particle tracer and the thermal technique, while mixing times were measured using the thermal technique. Newtonian fluid and two non-Newtonian fluids were used to simulate the operational conditions. The results showed that the change from Newtonian to non-Newtonian properties reduces mixed zones and increases circulation and mixing times. Circulation time was similar when evaluated with the thermal and the tracer particle methods. It was possible to predict dimensionless mixing time (θ _m) using an equivalent Froude number (Fr _eq).     

Charge localization in stacked radical cation DNA base pairs and the benzene dimer studied by self-interaction corrected density-functional theory

The incomplete cancellation of the electron self-interaction can be a serious shortcoming of density-functional theory especially when treating odd-electron systems. In this work, several popular and potentially viable correction schemes are applied in order to characterize the electronic structure of stacked molecular pairs, consisting of a neutral molecule and adjacent radical cation, as a function of separation distance. The unphysical sharing of the positive charge between adjacent molecules separated by 6-7 A is corrected for by applying a new empirical scheme proposed by VandeVondele and Sprik [Phys. Chem. Chem. Phys. 2005, 7, 1363] with a unique choice of parameters. This method is subsequently applied to characterize the electronic structure of two neighboring guanines excised from a canonical Arnott B-DNA structure and will be used in future investigations of certain model DNA fibers.     

New approach to the numerical solution of forward-backward equations

This paper is concerned with the approximate solution of functional differential equations having the form: x′(t) = αx(t) + βx(t - 1) + γx(t + 1). We search for a solution x, defined for t ∈ [−1, k], k ∈ ℕ, which takes given values on intervals [−1, 0] and (k-1, k]. We introduce and analyse some new computational methods for the solution of this problem. Numerical results are presented and compared with the results obtained by other methods.      

Magneto-optical properties of Cd(1-x)Mn(x)S nanoparticles: influences of magnetic doping, Mn2+ ions localization, and quantum confinement

Cd(1-x)Mn(x)S nanoparticles (NPs) were successfully grown in a glass matrix and investigated by optical absorption (OA), magnetic circularly polarized photoluminescence (MCPL) measurements, and magnetic force microscopy (MFM). The room temperature OA spectra have revealed the formation of two groups of Cd(1-x)Mn(x)S NPs with different sizes: bulk-like nanocrystals (NCs) and quantum dots (QDs). The MCPL spectra were recorded at 2.0 K with several magnetic fields up to 15 T, allowing a detailed comparison between the degrees of circular polarization of the two groups of NPs. The different behaviours of magneto-optical properties of bulk-like NCs and QDs were explained by taking into account a considerable alteration of exchange interaction between the carrier spins and the substitutional doping magnetic ions incorporated into the NPs. As a main result, we have demonstrated that self-purification is the dominant mechanism that controls the doping in semiconductor QDs grown by the melting-nucleation synthesis approach due to the relatively high temperature that was used in thermal annealing of samples.     

TOF-SIMS study of cystine and cholesterol stones

Two different human stones, cystine and cholesterol from the kidney and gall bladder, were examined by time-of-flight secondary ion mass spectrometry using Ga(+) primary ions as bombarding particles. The mass spectra of kidney stone were compared with those measured for the standard compounds, cystine and cysteine. Similar spectra were obtained for the stone and cystine. The most important identification was based on the existence of the protonated molecules [M + H](+) and deprotonated molecules [M-H](-). The presence of cystine salt was also revealed in the stone through the sodiated cystine [M + Na](+) and the associated fragments, which might be due to the patient treatment history. In the gallstone, the deprotonated molecules [M-H](+) of cholesterol along with relatively intense characteristic fragments [M-OH](+) were detected.     

Thioorthoesters in the activated Pictet-Spengler cyclization. Synthesis of 1-thiosubstituted tetrahydroisoquinolines and carboncarbon bond formation via sulfonyl iminium ions generated from N,S-sulfonyl acetals

The elaboration of 1-alkylthio- and 1-arylthio-tetrahydroisoquinolines by means of the activated Pictet-Spengler reaction of N-sulfonyl-β-phenethylamines with thioorthoesters as electrophiles, and their use as sulfonyl iminium ion precursors for carboncarbon bond formation, leading to 1-substituted tetrahydroisoquinoline derivatives, is reported.     

Hartog’s Type Extension Theorem in Some Piecewise Constant Structure Relations For Metamonogenic Functions of First Order

The main purpose of this paper is to study a Hartog’s type extension theorem for a more general class of functions, called, metamonogenic and multi-metamonogenic functions, with a Clifford type algebraic structure, called, some piecewise constant structure relations.     

1.1 MW peak-power, 7 W average-power, high-spectral-brightness, diffraction-limited pulses from a photonic crystal fiber amplifier

We report a large-core, Yb-doped photonic crystal fiber amplifier generating diffraction-limited (M2 = 1.04), approximately 0.45 ns, approximately 8 GHz linewidth pulses with energies of 540 microJ, peak power in excess of 1.1 MW, and average power of approximately 7.2 W at a repetition rate of 13.4 kHz. The pulse peak spectral brightness exceeds 10 kW/(sr Hz cm2) and is the highest generated by a fiber source, to our knowledge.