Induced Zinc Loss Produces Heterogenous Biological Responses in Melanoma Cells

Zinc levels in serum and/or tissue are reported to be altered in melanoma with unknown effects on melanoma development and biology. The purpose of this study was to examine the effects of acute chelation of free intracellular zinc pools in melanoma cell lines Bowes and A375, as well as selected melanoma tissue explants with high or low intracellular free zinc. Zinc chelating agent TPEN at the concentration of 25 µM was employed during 48 h, which significantly reduced intracellular free zinc while decreasing melanoma cell proliferation, inducing G1/S arrest and cell damage leading to mitochondrial, caspase-dependent apoptosis. Chelation of free zinc was also associated with increased generation of superoxide in cell lines but not marked lysosomal membrane damage. Conversely, melanoma explant cultures mostly displayed time-dependent loss of lysosomal membrane integrity in the presence of slowly growing superoxide levels. Loss of free zinc-dependent p53 activity was similarly disparate in individual melanoma models. Surviving melanoma cells were arrested in the cell cycle, and varying proportions of them exhibited features characteristic of premature senescence, which increased in time despite zinc reloading. The present results show that melanoma cells with varying free zinc levels respond to its acute loss in a number of individual ways, reflecting activated mechanisms including oxidative stress, lysosomal damage, and p53 activity leading to heterogenous outcomes including cell death, transient, and/or permanent cell cycle arrest and premature senescence.     

New voltage-mode universal filter and sinusoidal oscillator using only single DBTA

In this article, a new voltage-mode second-order universal frequency filter and sinusoidal oscillator using only single differential-input buffered and transconductance amplifier (DBTA) is presented. The proposed voltage-mode filter structure using single DBTA and four passive elements can provide all standard filter functions, i.e. low-, band-, high-pass, band-stop, and all-pass without changing the circuit topology and enables independent control of the quality factor Q using single passive element. The circuit requires the minimal number of active and passive elements with no conditions for component matching. By slight modification of the proposed filter structure, the new DBTA-based sinusoidal oscillator is easily obtained. The oscillation condition and the oscillation frequency are independently adjustable by different virtually grounded passive elements. The proposed sinusoidal oscillator employs only grounded capacitors. The passive and active sensitivities of all the proposed circuit configurations are low. PSPICE simulations using a BJT realisation of DBTA and experimental results based on commercially available amplifiers OPA860 and MAX436 are included, which prove the workability of the proposed circuits.     

Voltage-mode multifunction filter with mutually independent Q and \omega _0 control feature using VDDDAs

The paper focuses on the application possibilities of the newly presented voltage differencing active building block called voltage differencing differential difference amplifier. Using this active element, a multifunction frequency filter is designed featuring the possibility of mutually independent control of quality factor Q and characteristic frequency \(\omega _0\) by means of active elements. The structure of the filter is based on the idea of the Akerberg-Mossberg (AM) filter, i.e. the integrators in the structure are always realized only by two active elements. This fact results in better phase compensation for the filter. Compared to the AM opamp based filter, the newly proposed structure features high-impedance inputs, low-impedance output, and all basic frequency responses. The performance of the proposed structure has been verified by SPICE simulations using the TSMC \(0.18\,\upmu \hbox {m}\) level-7 SCN018 CMOS process parameters with \(\pm 0.9\,\hbox {V}\) supply voltage.     

New resistorless and electronically tunable realization of dual-output VM all-pass filter using VDIBA

In this paper, a new active element called voltage differencing inverting buffered amplifier (VDIBA) is presented. Using single VDIBA and a capacitor, a new resistorless voltage-mode (VM) first-order all-pass filter (APF) is proposed, which provides both inverting and non-inverting outputs at the same configuration simultaneously. The pole frequency of the filter can be electronically controlled by means of bias current of the internal transconductance. No component-matching conditions are required and it has low sensitivity. In addition, the parasitic and loading effects are also investigated. By connecting two newly introduced APFs in open loop a novel second-order APF is proposed. As another application, the proposed VM APF is connected in cascade to a lossy integrator in a closed loop to design a four-phase quadrature oscillator. The theoretical results are verified by SPICE simulations using TSMC 0.18 μm level-7 CMOS process parameters with ±0.9 V supply voltages. Moreover, the behavior of the proposed VM APF was also experimentally measured using commercially available integrated circuit OPA860 by Texas Instruments.     

Cyberbullying,cyber aggression and their impact on the victim – The teacher

This paper focuses on the results of the national research of cyberbullying of Czech teachers, which was realized in year 2016 in the entire Czech Republic. The research focused on impact of cyberbullying on teachers – especially in emotional, physiological and behavioural area. The research involved a total of 5136 primary and secondary school teachers from all regions of the Czech Republic. The research has shown that a fifth of respondents (21.73%) has experienced a cyber-attack on their person, however cyberbullying during the last 12 months lasting over 1 week was confirmed only by 3.52% of the total number of respondents.     

Polynomial time solution to minimum forwarding set problem in wireless networks under disk coverage model

In this paper, we consider a practical problem, called Minimum Forwarding Set Problem (MFSP), that emerges within the context of implementing (energy efficient) communication protocols for wireless ad hoc or sensor networks. For a given node v, MFSP asks for a minimum cardinality subset of 1-hop neighbors of v to cover v’s 2-hop neighbors. MFSP problem is also known as multi-point relay (MPR) problem. It is shown to be an NP-complete problem for its general case that does not consider the coverage characteristics of wireless transmissions. In this paper, we present two polynomial time algorithms to solve the MFSP problem under disk coverage model for wireless transmissions. In our earlier work, we presented a polynomial time algorithm for this problem under unit disk coverage model. In the current work, we present several observations on the geometric characteristics of wireless transmissions under disk coverage model and build two alternative dynamic programming based solutions with different run time and space complexities to the problem. Disk coverage model is a more general model because it allows nodes to use arbitrary power levels for transmissions. As a result, the presented algorithms provide a more practical solution that can be used as a building block for energy efficient communication protocols designed for wireless ad hoc and sensor networks.     

Understanding the Chena Hot Springs,Alaska, geothermal system using temperature and pressure data from exploration boreholes

Chena Hot Springs is a small, moderate temperature, deep circulating geothermal system, apparently typical of those associated to hot springs of interior Alaska. Multi-stage drilling was used in some exploration boreholes and was found to be useful for understanding subsurface flow characteristics and developing a conceptual model of the system. The results illustrate how temperature profiles illuminate varying pressure versus depth characteristics and can be used alone in cases where staged drilling is not practical. The extensive exploration activities helped define optimal fluid production and injection areas, and showed that the system could provide sufficient hot fluids (∼57 °C) to run a 400-kWe binary power plant, which came on line in 2006.     

使用DSC简化功率因数校正

本文描述了运用平均电流模式控制技术来设计和实现全数字功率因数校正（PFC）电路的方法。所述设计中数字信号控制器（DSc）的输入信号与通过升压电感的电流、升压转换器输出电容两端的直流母线电压,以及经整流的交流输入电压成正比,由DSC提供脉宽调制信号来控制PFC开关的导通时间。此技术旨在简化PFC,因而可整合于数字电源转换和电机控制应用中。     

An automated HPLC determination of meticlorpindol in eggs with UV absorbance detection, using on-line dialysis and pre-concentration as sample clean-up; occurrence in and carry over to eggs

Summary A fully automated HPLC determination of the coccidiostat meticlorpindol in whole egg, egg white and yolk is described. The sample homogenate is dialysed online against water. The dialysate is concentrated on-line on a short reversed-phase (RP) column. The contents of this column are transferred to the reversed-phase analytical column by means of the mobile phase. Meticlorpindol is detected using an absorbance detector at 270 nm. Linear calibration graphs are obtained in the range 40–900 ng/g in whole egg and egg white (detection limit 10 ng/g) and 80–1800 ng/g in yolk (detection limit 20 ng/g). Out of 111 commercially obtained egg samples 12 contained meticlorpindol with levels varying from 10 to 433 ng/g. A group of laying hens, kept in cages, received 10 mg/kg of Lerbek (meticlorpindol and methylbenzoquate; Dow Chemical) in the feed for 10 days. Meticlorpindol residues in the eggs rose to a level of 622 ng/g. Meticlorpindol was found in the eggs until 6 days after withdrawal of the medicated feed. Another group received 110 mg/kg in the feed. Meticlorpindol residues rose to levels of 4480 ng/g in the eggs, 5880 ng/g in the egg white and 2660 ng/g in the yolk. Meticlorpindol was found in the eggs and the egg white until 14 days and in the yolk until 8 days after withdrawal of the medicated feed.

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Eine automatisierte HPLC-Methode zur Bestimmung von Meticlorpindol in Eiern mit UV-Detektion und Probenaufarbeitung mit direkter Dialyse und direkter Vorkonzentrierung; Übertragung (Carry-over) und Vorkommen in Eiern

Zusammenfassung Mit dem beschriebenen Verfahren können Rückstände von Meticlorpindol in Eiern, Eiklar und Dotter automatisch bestimmt werden. Homogenisierte Proben werden gegen Wasser dialysiert. Das Dialysat wird an einer Vorkonzentrierungssäule konzentriert. Mit der mobilen Phase wird das Konzentrat auf die analytische Säule gebracht. Der Nachweis wird mit einem UV-Absorption-Detektor ausgeführt (Wellenlänge 270 nm). Der Zusammenhang zwischen Meßwert und Meticlorpindolgehalt ist linear in dem Bereich von 40 bis 900 ng/g Meticlorpindol in Vollei und Eiklar (Nachweisgrenze etwa 10 ng/g) und von 80 bis 1800 ng/g in Dotter (Nachweisgrenze etwa 20 ng/g). Bei der Untersuchung von 111 Handelsproben wurden in 12 Proben Rückstände von Meticlorpindol nachgewiesen mit Konzentrationen zwischen 10 und 433 ng/g. Eine Gruppe von Legehennen erhielt 10 mg/kg Lerbek (Meticlorpindol und Methylbenzoquate; Dow Chemical) im Futter während 10 Tagen. Die Eier wiesen bis zum 6. Tag nach dem Absetzen des Futterzusatzes nachweisbare Meticlorpindol-Rückstände auf (Höchstgehalt 622 ng/g in Vollei). Eine zweite Gruppe erhielt 110 mg/kg im Futter. In den Volleiproben und Eiklarproben dieser Gruppe konnten bis zum 14. Tag nach dem Absetzen Rückstände von Meticlorpindol nachgewiesen werden (Höchstgehalte 4480 und 5880 ng/g), in den Dotterproben bis zum 8. Tag (Höchstgehalt 2660 ng/g).