Near axisymmetric partial wetting using interface-localized liquid dielectrophoresis

The wetting of solid surfaces can be modified by altering the surface free energy balance between the solid, liquid, and vapour phases. Liquid dielectrophoresis (L-DEP) can produce wetting on normally non-wetting surfaces, without modification of the surface topography or chemistry. L-DEP is a bulk force acting on the dipoles of a dielectric liquid and is not normally considered to be a localized effect acting at the interface between the liquid and a solid or other fluid. However, if this force is induced by a non-uniform electric field across a solid -liquid interface, it can be used to enhance and control the wetting of a dielectric liquid. Recently, it was reported theoretically and experimentally that this approach can cause a droplet of oil to spread along parallel interdigitated electrodes thus forming a stripe of liquid. Here we show that by using spiral shaped electrodes actuated with four 90º successive phase shifted signals, a near axisymmetric spreading of droplets can be achieved. Experimental observations show that the induced wetting can achieve film formation, an effect not possible with electrowetting. We show that the spreading is reversible thus enabling a wide range of partial wetting droplet states to be achieved in a controllable manner. Furthermore, we find that the cosine of the contact angle has a quadratic dependence on applied voltage during spreading and deduce a scaling law for the dependence of the strength of the effect on the electrode size

Uncertainties in linear energy transfer spectra measured with track-etched detectors in space

Polyallyldiglycol carbonate-based track-etched detectors can measure linear energy transfer (LET) spectra of charged particles. Accuracy of the spectra is affected by many factors whose effects are difficult to quantify. Typically, only uncertainty arising from the randomness of particle detection is reported in scientific literature. The aim of this paper is to classify the sources of uncertainties of an LET spectrum measurement and provide a simple model for the calculation of the combined uncertainty. The model was used for a spectrum measured with the track-etched detector (Harzlas TD-1) on board of the International Space Station from May-October 2009. For some spectrum bins the largest contribution to the combined uncertainty came from the uncertainty arising from the randomness of particle detection. For other bins it came from the uncertainty of the calibration curve. Contribution from the cross talk between bins was small for most of the bins as the width of the bins was relatively large compared to the intrinsic resolution of the track-etched detector. The analysis showed that sources of uncertainties other than the randomness of particle detection should not, in general, be neglected

Measurement of dose equivalent distribution on-board commercial jet aircraft

The annual effective doses of aircrew members often exceed the limit of 1 mSv for the public due to the increased level of cosmic radiation at the flight altitudes, and thus, it is recommended to monitor them [International Commission on Radiation Protection. 1990 Recommendations of the International Commission on Radiological Protection. ICRP Publication 60. Ann. ICRP 21(1–3), (1991)]. According to the Monte Carlo simulations [Battistoni, G., Ferrari, A., Pelliccioni, M. and Villari, R. Evaluation of the doses to aircrew members taking into consideration the aircraft structures. Adv. Space Res. 36, 1645–1652 (2005) and Ferrari, A., Pelliccioni, M. and Villari, R. Evaluation of the influence of aircraft shielding on the aircrew exposure through an aircraft mathematical model. Radiat. Prot. Dosim. 108(2), 91–105 (2004)], the ambient dose equivalent rate H_ ð10Þ depends on the location in the aircraft. The aim of this article is to experimentally evaluate H_ ð10Þ on-board selected types of aircraft.The authors found that H_ ð10Þ values are higher in the front and the back of the cabin and lesser in the middle of the cabin. Moreover, total dosimetry characteristics obtained in this way are in a reasonable agreement with other data, in particular with the above-mentioned simulations

Dose Distribution Outside the Target Volume for 170-Mev Proton Beam

Dose delivered outside the proton field during radiotherapy can potentially lead to secondary cancer development. Measurements with a 170-MeV proton beam were performed with passive detectors (track etched detectors and thermoluminescence dose-meters) in three different depths along the Bragg curve. The measurement showed an uneven decrease of the dose outside of the beam field with local enhancements. The major contribution to the delivered dose is due to high-energy protons with linear energy transfer (LET) up to 10 keV mu m(-1). However, both measurement and preliminary Monte Carlo calculation also confirmed the presence of particles with higher LET

Epithelial cells modulate genes associated with NF kappa B activation in co-cultured human macrophages

Macrophages located in airways and the alveolar space are continually exposed to different signals from the respiratory mucosa. In this respect, epithelial cells represent an important source of cytokines and mediators modulating the state of activation and/or differentiation of mononuclear phagocytes. Many of the proinflammatory genes induced in macrophages during immune and immunopathological reactions are regulated by transcription factor NF kappa B. The aim of our study was to characterize changes in the expression of genes associated with NF kappa B activation and signalling in THP-1 human macrophages co-cultured with A549 respiratory epithelial cells. At least 4-fold upregulation of mRNA level was found in 29 of 84 tested genes including genes for multiple cytokines and chemokines, membrane antigens and receptors, and molecules associated with NF kappa B signalling. The mRNA induction was confirmed at the level of protein expression by evaluating the release of IL-6 and IL-8 and by ICAM-1 expression. Blocking of one NFκB subunit by p65 siRNA inhibited the production of IL-6 in both cell types while IL-8 release from THP-1 cells did not seem to be affected. We conclude from our data that unstimulated respiratory epithelial cells regulate genes associated with NF kappa B dependent immune responses in human macrophages and that these interactions may play a key role in immediate responses in the respiratory mucosa

The Best possible Time resolution: How precise could a Radiocarbon dating method be?

Today, accelerator mass spectrometry (AMS) technology enables us to carry out very precise measurements of radiocarbon (C-14). Unfortunately, due to fluctuations in the C-14 calibration curve, the resulting calibrated time intervals vary from decades up to centuries in calibrated age. Within a time scale of several decades, we can find several time intervals on the C-14 calibration curve which correspond with periods of rapid increases in atmospheric (CO2)-C-14 activity. Some of these "high slope" parts of the calibration curve could be used for fine time resolution for radiocarbon dating of individual samples. Nevertheless, there are certain limitations owing to the properties of the samples measured. We have prepared a time-resolution curve for the C-14 dating method, applying calibration curve IntCal13 and assuming an uncertainty of C-14 analyses +/- 15 yr BP (for recent samples). Our curve of the time resolution covers the last 50 ka. We found several time intervals with time resolution below 50 yr BP for the last 3 ka. Several time intervals which can enable substantially better time resolution compared to neighboring parts of the calibration curve were also found for periods older than 3 ka.OP RDE, MEYS [CZ.02.1.01/0.0/0.0/16_019/0000728]; Nuclear Physics Institute of the Czech Academy of SciencesCzech Academy of Sciences [RVO61389005]; Czech Republic Grant AgencyGrant Agency of the Czech Republic [17-22102s, GA18-11004S]; European UnionEuropean Union (EU); State of Hungary; European Regional Development FundEuropean Union (EU) [GINOP-2.3.2-15-2016-00009]Open access articleThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]