An inequality for the modified Selberg zeta-function

The Ramanujan Journal - We consider the absolute values of the modified Selberg zeta-function at places symmetric with respect to the critical line. We prove an inequality for the modified Selberg...     

Ag/DNQ-novolac-based nanocomposite films for controllable UV lithography morphological patterning

In this study, the detailed characterisation of silver (Ag) nanoparticles/polymer nanocomposite chemical structure and morphology of grating has been carried out. Scanning electron microscopy measurements show spherical shape of Ag nanoparticles (40–80 nm in diameter) prepared in chloroform by reduction of silver nitrate. In the positive photoresist based on 2-diazo-2H-naphthalen-1-one (DNQ)–novolac, Ag nanoparticles were deposited from organic colloidal solution. The content of nanoparticles in the polymer matrix was varied by increasing the concentration of Ag colloidal solution. Grating was formed by contact lithography. The quantification of Ag nanoparticles and chemical analysis of Ag/DNQ-novolac-based nanocomposite was performed by means of energy dispersive X-ray analyzer and SEM/EDS. In order to study the effect of Ag nanoparticles on the DNQ-novolac-based nanocomposite structure, investigations with Fourier transform infrared spectroscopy were conducted. Ag nanoparticles cause changes associated with substituent-sensitive out-of-plane C–H bending vibrations of aromatic ring. Ag/DNQ-novolac-based nanocomposite film surface morphology and grating topography imaging were performed using atomic force microscopy. Added Ag nanoparticles change the geometrical parameters of the gratings. The split of corrugations was achieved in Ag/DNQ-novolac-patterned films. Their morphology can be tailored by altering the content of Ag nanoparticles.     

A central limit theorem for coefficients of the modified Borwein method for the calculation of the Riemann zeta-function

Lithuanian Mathematical Journal - The paper extends the study of the modified Borwein method for the calculation of the Riemann zeta-function. We present an alternative perspective on the proof of...     

Characterization of Plasma Polymerized Hexamethyldisiloxane Films Prepared by Arc Discharge

Herein, we present a simple method for fabricating plasma polymerized hexamethyldisiloxane films (pp-HMDSO) possessing superhydrophobic characteristics via arc discharge. The pp-HMDSO films were deposited on a soda–lime–silica float glass using HMDSO monomer vapor as a precursor. A detailed surface characterization was performed using scanning electron microscopy and atomic force microscopy. The growth process of the pp-HMDSO films was investigated as a function of deposition time from 30 to 300 s. The non-wetting characteristics of the pp-HMDSO films were evaluated by means of contact angle (CA) measurements and correlated with the morphological characteristics, as obtained from microscopy measurements. The deposited films were found to be nano-structured and exhibited dual-scale roughness with the static CA values close to 170°. Fourier transform infrared spectroscopy analysis was carried out to investigate chemical and functional properties of these films. Methyl groups were identified spectroscopically to be present within the pp-HMDSO films and were proposed to result in the low surface energy of material. The synergy between the dual-scale roughness and low surface energy resulted in the superhydrophobic characteristics of the pp-HMDSO films. A possible mechanism for the pp-HMDSO film formation is proposed.     

Mixed-Stable Models: An Application to High-Frequency Financial Data

The paper extends the study of applying the mixed-stable models to the analysis of large sets of high-frequency financial data. The empirical data under review are the German DAX stock index yearly log-returns series. Mixed-stable models for 29 DAX companies are constructed employing efficient parallel algorithms for the processing of long-term data series. The adequacy of the modeling is verified with the empirical characteristic function goodness-of-fit test. We propose the smart-Δ method for the calculation of the α-stable probability density function. We study the impact of the accuracy of the computation of the probability density function and the accuracy of ML-optimization on the results of the modeling and processing time. The obtained mixed-stable parameter estimates can be used for the construction of the optimal asset portfolio.     

Synthesis and characterization of layered double hydroxides with different cations (Mg,Co, Ni,Al), decomposition and reformation of mixed metal oxides to layered structures

Three layered double hydroxides (LDH) [Mg_1−xAl_x(OH)₂]^x+(A^m−)_x/m]·nH₂O and [M^II _1−xM^III _x (OH)₂]^x+(A^m−)_x/m]·nH₂O (M^II — Mg, Co, Ni; MIII — Al; A — CO₃ ²⁻) were successfully synthesized by the low supersaturation method. The as-synthesized LDH samples were thermally decomposed and the derived mixed metal oxides reformed back to layered structures in water and magnesium nitrate media at different temperatures. All synthesized samples were characterized by X-ray diffraction (XRD) analysis, thermogravimetric (TG) analysis, X-ray fluorescence (XRF) analysis and scanning electron microscopy (SEM). The results of XRD and XRF analyses showed that single-phase layered double hydroxides were formed during synthesis and reformation. It was demonstrated, that a partially substituted by cobalt and nickel LDH samples also show memory effect. The crystallite size of regenerated LDH depends on the regeneration media, temperature and chemical composition. The LDH samples after regeneration consist of large particles with sharp edges along with a large amount of smaller particles     

Electrodeposition of Mo-Se thin films from a sulfamatic electrolyte

Mo-Se thin films have been electrodeposited on conducting tin oxide (SnO₂) coated glass substrates from a sulfamatic solution containing Na₂MoO₄ and H₂SeO₃ under potentiostatic conditions. The deposition potential varied from –0.6 V to –0.9 V, at a deposition temperature of 20–40 °C and pH 6.5. X-ray diffraction analysis revealed that the overall composition of the films deposited is consistent with the formation of MoO₂ and MoSe₂. The lattice parameters of the as-deposited MoSe₂ are a=b=3.2340 Å and c=13.2859 Å, which fits a hexagonal structure.