A potentiometric study of some solution equilibria involving biological ligands and transition metal ions

The formation constants for several metal ion-ligand complexes have been measured by glass electrode potentiometry in aqueous solution at 37°C using an ionic background of 150mM sodium perchlorate. The three topics comprising this thesis are (i) a study of the reaction of several metal ions, namely Co(II), Ni(II), Cu(II) and Zn(II), with ligands such as adeninate, cyclohexylamine and cyclopentylamine. These were studied in order to gain experience in the techniques of potentiometry and computation. (ii) The second topic, which comprises the major portion of the thesis, involved the in vitro study of zinc complexes with a series of ligands which can be divided into two groups; those containing only oxygen donor groups (acetate, galacturonate, hydroxybutyrate, malate, malonate, oxalate, salicylate and tartarate) and those which contain oxygen and nitrogen donor groups (glycinate, glycylglycinate and glycylglycylglycinate); the purpose of this investigation being to suggest the best zinc supplementing drug for treating zinc deficiency conditions. Hydroxybutyrate and galacturonate are suggested to be the most promising ligands for zinc absorption. (iii) Finally, computer simulation models of equilibria involving zinc and ligands in intestinal solution were used to correlate the rate of growth of turkey poults with the type of metal-ligand complexing occurring in intestinal fluid

Analysis of meteorology-chemistry interactions during air pollution episodes using online coupled models within AQMEII Phase-2

This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).This study reviews the top ranked meteorology and chemistry interactions in online coupled models recommended by an experts’ survey conducted in COST Action EuMetChem and examines the sensitivity of those interactions during two pollution episodes: the Russian forest fires 25 Jul -15 Aug 2010 and a Saharan dust transport event from 1 Oct -31 Oct 2010 as a part of the AQMEII phase-2 exercise. Three WRF-Chem model simulations were performed for the forest fire case for a baseline without any aerosol feedback on meteorology, a simulation with aerosol direct effects only and a simulation including both direct and indirect effects. For the dust case study, eight WRF-Chem and one WRF-CMAQ simulations were selected from the set of simulations conducted in the framework of AQMEII. Of these two simulations considered no feedbacks, two included direct effects only and five simulations included both direct and indirect effects. The results from both episodes demonstrate that it is important to include the meteorology and chemistry interactions in online-coupled models. Model evaluations using routine observations collected in AQMEII phase-2 and observations from a station in Moscow show that for the fire case the simulation including only aerosol direct effects has better performance than the simulations with no aerosol feedbacks or including both direct and indirect effects. The normalized mean biases are significantly reduced by 10-20% for PM10 when including aerosol direct effects. The analysis for the dust case confirms that models perform better when including aerosol direct effects, but worse when including both aerosol direct and indirect effects, which suggests that the representation of aerosol indirect effects needs to be improved in the model.Peer reviewedFinal Published versio

Microstrip antennas with ring hybrid feeding structures for in-band full-duplex applications

The information age has led to crowding of the consumer wireless network as more devices are using the same, limited frequency band. Currently these devices must operate at two frequencies, one to transmit, and one to receive, due to their compact nature. Were they to do both at the same frequency, there would be a high level of self-interference, in which the receive signal of a device would carry much of the transmit signal of that very same device because of the nearness of the signal. If this issue could be resolved such that each device could both transmit and receive at one frequency at any time, the capacity of these crowded wireless networks could be theoretically doubled. Such operation is known as in-band full-duplex. Presented here are three microstrip antenna system designs for use in in-band full-duplex applications. The radiating elements of the design are two monopoles, a probe-fed patch, and an aperture-fed patch, respectively. All three designs utilize a 180° ring hybrid element to reduce self-interference between a transmit and receive port. They are designed to operate in the 2.4 GHz WLAN band. The monopole design has a bandwidth of 100 MHz (4.2%), the probe-fed patch design 60 MHz (2.5%) and the aperture-fed patch design 40 MHz (1.7%). Measured in a reflective environment, throughout the operational band the monopole design has measured isolation below -35 dB, the probe-fed patch design -30 dB, and the aperture-fed patch design -45 dB. However, the peak measured isolation is instead -45 dB for the monopole design, -50 dB for the probe-fed patch design, and -60 dB for the aperture-fed patch design. All three designs offer reasonable gain and good radiation patterns that act omnidirectional or semi-omnidirectional. They are more compact than other antenna system designs meant to reduce self-interference that accomplish similar levels of reduction. These other attempts will be discussed in brief. Due to high levels of isolation and good efficiency, the designs also offer envelope correlation coefficients well below the accepted 0.3 threshold for multiple-input multiple-output designs, used here to quantify our simultaneous transmit and receive design

New Directions : Understanding interactions of air quality and climate change at regional scales

The estimates of the short-lived climate forcers’ (SLCFs) impacts and mitigation effects on the radiation balance have large uncertainty because the current global model set-ups and simulations contain simplified parameterizations and do not completely cover the full range of air quality-climate interactions (AQCI). Most AQCI studies to date used coarse grid models that cannot adequately resolve the highest SLCFs concentrations in the densest source regions and mesoscale circulations/processes (Anderson et al., 2003). Therefore, the radiative and vertical transport impacts and associated air quality issues in coarse grid models are likely to be under-represented at the regional and local scales. Since AQCI can be locally predominant due to the heterogeneity in emissions loading and process interactions, regional models capable of capturing AQCI are critically needed so that the cumulative effects on larger scale radiative forcing of the earth-atmosphere can be accurately assessed. Regional models include detailed physical, dynamical, and chemical formulations. However, the credibility of these models in properly simulating AQCI has not been critically assessed, a necessary step before they could be used more confidently for developing effective regulatory policies.Peer reviewe