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The main process that ensures the production of bread as a marketable product is the external thermal energy supply during baking. This process is accompanied by a complex physical phenomenon - moisture exchange between the dough-bread with the external environment and the steam-air environment of the baking chamber, as well as internal heat and mass transfer in the heated dough piece. At the same time, biochemical processes associated with the transformation of starch and proteins. Taking into account that the main factor realizing the efficiency and quality indicators of baked bread is heat exchange in the dough piece, in this article, taking into account the peculiarities of the dynamics of the heat transfer phenomenon, a quantitative analysis of the course of this process is carried out. In this work, in contrast to the results obtained by other researchers in the field of calculating the processes of heat treatment of food products, a quantitative analysis of the process is proposed based on a new methodological approach to the problem of physical and mathematical substantiation of the heat transfer process in a dough piece. That can be effectively used in the simulation of innovative samples of baking equipment.

In this work, it is shown that intensive treatment of dispersed systems with ultrasound is an effective method for enhancing the interaction of particles and polymer with the subsequent formation of adsorption layers of high thickness and strength. This makes possible to obtain highly stable dispersed systems with a modified surface of the solid phase. The studies proved the important role of intensive ultrasonic action for controlling the properties of the nanoparticles surface in heterophase systems. It is shown that an increase in the activity of the surface of nanoparticles as a result of ultrasonic treatment is of great importance for the study of their antibacterial activity: after ultrasonic activation, nanoparticles are more active in interaction with cell membranes.

Recent discoveries in nonlinear optical properties of nanoparticle colloids make actual the challenge to lower the energy threshold of phase conjugation and move it into the domain of shorter pulse widths. A novel effect of the stimulated Rayleigh-Mie scattering (SRMS) in two-photon absorbing nanocolloids is considered as a promising answer to this challenge. We report the results of experimental and theoretical study of the two-photon-assisted SRMS in Ag and ZnO nanocolloids in the nanosecond-to-picosecond pulse width domain. For 12 ns 0.527 μm laser pulses, the four-wave mixing SRMS scheme provides lasing and amplification of backscattered anti-Stokes signal in Ag nanocolloids in toluene at the threshold 0.2 mJ and the spectral shifts up to 150 MHz. For 100 ps 0.532 μm pulses, we observed for the first time efficient (over 50% in signal-to-pump ratio of pulse energies) SRMS backscattering of the anti-Stokes signal in Ag nanocolloids in toluene and predominantly Stokes signal in ZnO nanocolloids in water, with the spectral shifts up to 0.25 cm−1. We develop the first order-in-perturbation model of the four-wave mixing two-photon absorption-assisted SRMS process which shows that at nanosecond pulses, amplification is predominantly due to the thermal-induced coherent oscillations of polarization while the slow temperature wave acts also as a dynamic spatial grating which provides a self-induced optical cavity inside the interaction region. At a picosecond pulse width, according to our model, the spectral overlap between pump and signal pulses results in formation of only the dynamic spatial temperature grating, and we succeeded at recovering the linear growth of the spectral shift with the pump power near the threshold. [ABSTRACT FROM AUTHOR]

It was presented the data on the thicknesses of the adsorbed polymer layer, which were obtained for copper phthalocyanine (CuPc) pigment dispersions under ultrasonic processing conditions. The thicker adsorption layers, which are observed in ultrasound systems, confirm the fact that the activation of the surface of the pigment occurs under the action of ultrasonic energy. The course and efficiency of adsorption of the polymer onto the pigment surface were quantified by electrokinetic measurements of the amplitude of sound (EIAZ). It became possible to obtain a more detailed picture of the pigment-polymer interactions and the adsorption mechanism of the copolymer based on the data on the dynamic mobility, obtained as a result of electrokinetic measurements of the amplitude of the sound. For aqueous dispersions of CuPc, stabilized with a copolymer of poly (acrylic acid) -poly (isobornyl acrylate) (PiBA-PAA), it was established the saturation concentrations of polymeric surfactant. Thus, the ultrasonic treatment allows to obtain stable, highly dispersed pigment suspensions with a modified pigment surface, which opens up new prospects for a more effective change in the surface of the pigment. [ABSTRACT FROM AUTHOR]

This paper discusses the study of the shapes and sizes of polymer droplets formed during the phase separation of their solutions with increasing temperature, as well as the parameters of the transitional layers of polymer condensing on the droplet surface formed during this process. For the study, a copolymer of polyethylene oxide and polypropylene oxide was chosen, whose behavior in aqueous solutions and the change in hydrophilic-hydrophobic balance depends on temperature. It has been established that the application of the method of digital image processing allows the introduction of the quantitative criterion - image intensity of a photo. For a more detailed study of the behavior of polymer molecules at the phase boundary, depending on the temperature, the studies of the temperature-dependent behavior of a number of polymers of different composition and structure have been carried out. The use of the digital image processing method for polymer droplets makes it possible to determine the parameters of droplets and their transition layers, to determine the dynamics of nucleation and droplet growth and density changes in the transition layer by the image intensity parameter. The paper has found out that embryos of pluronic are unevenly distributed by volume of solution with the presence of zones with a maximum number of molecules and a zone with a minimum of assembly of molecules. The practical value of the work is in the fact that the results of the study can be used to assess the dynamics of the separation of polymer solutions without involving the time-consuming and expensive instrumental methods of physical and chemical analysis. [ABSTRACT FROM AUTHOR]

The influence of the ultrasonic treatment of block copolymer solution on its solid-liquid interface behavior was investigated in detail. The surface modification of titanium dioxide nanoparticles in aqueous dispersions of specially tailor-made periodic acrylic acid/isobutylene copolymer by ultrasonic treatment was studied in order to get new approaches for the creation of hybrid composite materials or polymer coatings. The pigment surface modification by the above copolymer was comparatively investigated regarding conventional adsorption as contrasted to an ultrasonic treatment assisted procedure. The course and efficiency of the polymer adsorption onto the pigment surface were quantified by electrokinetic sonic amplitude measurements. The higher efficiency of the pigment surface coating by the copolymer as achieved by ultrasonic treatment in comparison to conventional adsorption is a consequence of ultrasonically induced pigment surface activation. Two perspective avenues of the utilization of the discovered effects for creation of organic-inorganic composite materials are anticipated: the nanoparticles could first be treated by ultrasound in the presence of polymers and so create a surface modifying coating and the second option is an entrainment of the nanoparticles into the monomer matrix which can be polymerized afterward yielding a polymer with immobilized nanoparticles. [ABSTRACT FROM AUTHOR]

Two new methods of preparation of nanocrystalline scintillators are described. Laser ablation of microscopic powders immersed in optically transparent liquid was used to produce spherical nanoparticles, which preserved the initial compositions. Electric arc discharge between electrodes of definite metals immersed in water solutions of different salts produces a vast variety of scintillating compounds with nanoscopic dimensions and morphologies having crystallographic symmetry of the corresponding equilibrium phases. A wide range of different compositions and structures of tungsten oxides are obtained during one synthesis process, which is due to variety of temperatures and other conditions around the arc channel. It was found that the light emission spectroscopy of the discharge is a rather informative method of diagnostics of the process of the nanoparticle synthesis inside the discharge chamber. The synthesis of nanoscintillators by arc discharge turned out to be rather efficient and capable to create nanocrystalline scintillators of easily regulated compositions. Hydrogen injection into nanoparticles of tungsten oxide is detected by light emission and infrared absorption spectroscopy. Hydrogenated nanoscintillators obtained by this method are interesting for registration of fast neutrons. [ABSTRACT FROM AUTHOR]

Stimulated Rayleigh-Mie scattering (SRMS) in two-photon absorption liquids is realized by a Fourier-transform-limited pulsed Nd-glass laser. For the first time, to the best of our knowledge, we have measured anti-Stokes spectral shifts of SRMS in toluene and hexane colloids of Ag nanoparticles, as well as in pure toluene. These values appreciably exceed the Rayleigh line width in those liquids. The four-wave mixing method is applied both experimentally and theoretically to display the process as Rayleigh-induced parametric generation. We show that the amplification effect is provided predominantly by thermally induced coherent polarization oscillations, while an interference-assisted thermal grating provides formation of a self-induced optical cavity inside the interaction region.