Pulsating combustion: Theoretical and empirical substantiation of ecological effect

There are two primary parameters that characterize operation of modern energy generation units that burn fuel, namely - unit efficiency and the amount of noxious emissions. Usually units that operate at the maximum efficiency produce maximum potential emissions of noxious substances (as NOx) into the atmosphere. This work provides theoretical substantiation for control of the combustion process by superimposing controlled irregularities to the fuel supply rate in order to suppress NOx generation while retaining the unit's technical parameters and cost efficiency. The substantiation uses known empirically obtained NOx generation dependency from the air excess ratio. Evaluation of the generated NOx content was performed using numerical integration of the composed time sequences describing changes in the NOx concentration in the combustion products for various types of control actions. Evaluation of bands of operating frequencies for the proposed method of combustion control are presented. The proposed theoretical substantiation made it possible to determine conditions and technics for experimental work. © 2017 Author(s)

Frequency-domain analysis for pulsating combustion of gaseous fuel

Pulsating combustion is among combustion control methods used to suppress formation of NOx. Past experiments showed that the dependency of NOx content from pulsation rate has a minimum. A measuring unit was set up to study torch behavior in infrared band. To study pulsating combustion of gaseous fuel a thermographic camera was used. Thermographic sequences were recorded using the instrument FLIR 7700M with the resolution of 320×240 pixels at the frame rate of 412 Hz. The experiments resulted in obtaining thermographic sequences radiation intensity fields in the longitudinal section of the torch at different pulsation rates. The obtained raw data was preprocessed to obtain distributions of quantities of pixels corresponding to temperatures in each frame, as well as time-domain series for changes of the torch core longitudinal section area. Frequency-domain analysis was run for each time-domain series using Fast Fourier transform (FFT). The results demonstrate that the first maximum of spectral density coincides with the control action rate. The spectrum also contains pronounced second and third harmonics. For each spectrum of the time-domain series signal-to-noise ratio (SNR) was calculated. Comparison of different SNR shows that maximum impact of pulsation control on torch radiation intensity takes place at the on/off valve opening rate of 4 Hz. This method of torch diagnostics can be helpful for future studies and development of pulsating combustion control systems. © 2017 Author(s)

Pulsation-based method for reduction of nitrogen oxides content in torch combustion products

Out of all ways to fuel bum the torch combustion systems is used most often. Even though the processes in the steam boiler are stochastic, the system can be controlled rather easily by changing the flowrate of the air pumped into it and - in case of balanced flue units - exhausters load. Advantages offered by torch-based combustion systems are offset by a disadvantage resulted in oxidation of nitrogen contained in the air. This paper provides rationale for an NOx content reduction method that employs pulsation mode of fuel combustion; it also describes combustion control and monitoring system employed for implementation of this method. Described methodology can be used not only for pulsation combustion studies but also for studies of torches formed by conventional burning systems. The outcome of the experimental study supports the assumption that it is possible to create conditions for NOx content reduction in flue gases by means of cycling the fuel supply on/off valve at the rate of 6 Hz. © Published under licence by IOP Publishing Ltd

DYNAMICS OF IL12 CYTOKINE EXPRESSION IN HUMAN MACROPHAGES AFTER TREATMENT WITH DIOXIN

Interleukin IL-12 is a key proinflammatory cytokine, synthesized by macrophages, but the information concerning the dioxin effect on its expression is still fragmentary. The presence of previously identified potential dioxin responsive elements (DREs) in the regulatory regions of IL12A and IL12B genes, encoding IL-12 subunits IL-12p35 and IL-12p40, respectively, suggests direct activation of these genes by binding of the dioxin/AhR/ARNT complex to DREs. This work proves the binding capacity of these DREs by gel shift assay. The study of the dynamics of IL12A and IL12B gene expression in the human macrophage cell line U937 revealed no influence of dioxin on IL12A expression. In contrast, activation of IL12B gene expression with subsequent inhibition was noted. The observed dynamics can be explained by direct activation of the expression by the dioxin-containing complex and subsequent inhibition of the expression because of oxidative stress caused by dioxin. Thus, the well-known dioxin influence on the immune system can be associated with the difference in the dioxin effect on the expression dynamics of the genes encoding IL-12 subunits

Three-dimensional growth of breast cancer cells potentiates the anti-tumor effects of unacylated ghrelin and AZP-531

Breast cancer is the most common type of cancer in women and notwithstanding important therapeutic advances, remains the second leading cause of cancer-related death. Despite extensive research relating to the hormone ghrelin, responsible for the stimulation of growth hormone release and appetite, little is known of the effects of its unacylated form, especially in cancer. The present study aimed to characterize effects of unacylated ghrelin on breast cancer cells, define its mechanism of action, and explore the therapeutic potential of unacylated ghrelin or analog AZP-531. We report potent anti-tumor effects of unacylated ghrelin, dependent on cells being cultured in 3D in a biologically-relevant extracellular matrix. The mechanism of unacylated ghrelin-mediated growth inhibition involves activation of Gαi and suppression of MAPK signaling. AZP-531 also suppresses the growth of breast cancer cells in vitro and in xenografts, and may be a novel approach for the safe and effective treatment of breast cancer