Top quark production in e+e- annihilation

We analyze the four-fermion reactions e+e- -> 4f containing a single top quark and three other fermions, a possible decay product of the resonant anti-top quark, in the final state. This allows us to estimate the contribution of the nonresonant Feynman graphs and effects related to the off mass shell production and decay of the top quark. We test the sensitivity of the total cross section at centre of mass energies in the t tbar threshold region and far above it to the variation of the top quark width. We perform calculation in an arbitrary linear gauge in the framework of the Standard Model and discuss an important issue of gauge symmetry violation by the constant top quark width.Comment: 9 pages, 2 figures. A revised version accepted for publication in the European Physical Journal C; a comment on the "fermion-loop scheme" modifie

Development of an electrochemical platform for the hemofiltration of platinum-based organometallic drugs

Cancerous diseases remain a major threat to human population causing millions of deaths every year. Chemotherapy, being a major treatment method, lacks selectivity towards cancerous cells what causes severe side effect in patients who underwent this treatment. Lower quality of life after chemotherapy stimulated research on technologies that could eliminate some of these drawbacks, but no breakthrough has been achieved yet. The overall aim of this project is to develop a novel concept of the electrochemical hemofiltration system for the removal of platinum-based anti-cancer drugs. Since this PhD thesis represents the first approach to develop the electrochemical hemofiltration system, it is mostly composed of systematic studies of aspects that are of key importance for the successful and safe performance of the system. The thesis is structured is the following way. Chapter 1 introduces a reader to the tackled problem and the state-of-the-art solutions. Chapter 2 presents the aims this thesis is aimed to accomplish. Chapter 3 includes a brief description of experimental techniques that were applied in the research project presents the aims this thesis is aimed to accomplish. Chapter 4 describes the electrochemical behaviour of cisplatin, a common anti-cancer drug, on the surface of gold. Chapter 5 describes factors that determine the stability of sulphur-based modifiers assembled on gold surface. Chapter 6 presents extensive studies on the coordination of cisplatin and other Pt-based molecules in both, homogeneous and heterogeneous phase. Finally, Chapter 7 concludes on the impact this work has on the electrochemical hemofiltration concept along with an insight into future directions of the project. This thesis provides proof-of-concept experiments that show a great potential of surface-modified electrode in capturing and quantification of Pt-based drugs in physiological medium

Factorizable electroweak O(alpha) corrections for top quark pair production and decay at a linear e+e- collider

We calculate the standard model predictions for top quark pair production and decay into six fermions at a linear e+ e- collider. We include the factorizable electroweak O(alpha) corrections in the pole approximation and QED corrections due to the initial state radiation in the structure function approach. The effects of the radiative corrections on the predictions are illustrated by showing numerical results for two selected six-fermion reactions e+ e- -> b nu_mu mu+ bar{b} mu- bar{nu_mu} and e+ e- -> b nu_mu mu+ bar{b} d bar{u}.Comment: 16 pages, 3 figures; a comment on the corrections that were not included in the paper and one reference added; accepted for publication in Eur. Phys. J.

Immunomagnetic detection of cancer cells in pleural effusion of generalized cancer

 Malignant pleural effusions (MPE) are a common clinical problem in patients with neoplastic disease. Pleural fluid cytology is the simplest definitive method for obtaining a diagnosis of MPE. We describe a method that may increase the cancer cell detection rate using immunomagnetic separation in MPE. In comparison to standard MPE cytodiagnostic methods, we report a more streamlined method of isolation living cells that are able to proliferate. These captured cells can then be used for additional downstream analysis e.g. chemosensitivity testing. Several case studies of MPE diagnostics using immunomagnetic separation are presented in the following report. The immunomagnetic separation of cancer cells from MPE could be used for more accurate staging of patients with routine effusions.

Phosphate-mediated electrochemical adsorption of cisplatin on gold electrodes

This manuscript reports the potential-dependent adsorption and deposition of cisplatin on polycrystalline gold electrode. It was found that this process is mediated by the adsorption of phosphate anions on the gold electrode and that the maximum coverage of Pt adsorbed is given by the maximum coverage of phosphate adsorbed at a given potential. The interaction of cisplatin with the phosphate groups was confirmed by in situ FTIR spectroscopy under external reflexion configuration. Quantitative analysis suggests that the stoichiometry of the phosphate species and the cisplatin adsorbed was 1:1. Moreover, the relationship between the charge of the Pt deposited and the charge of the electrochemical surface area of the Pt deposited on the gold electrodes indicates that 3D nanoclusters of a few atoms of Pt were formed over the gold electrode upon the electrochemical reduction of the adsorbed cisplatin.The Pt nanoclusters formed under these conditions were later evaluated for the oxidation of a monolayer of carbon monoxide. The Pt nanoclusters showed a high overpotential for the oxidation of the carbon monoxide monolayer and the high oxidation overpotential was attributed to the absence of adsorption sites for OH species on the Pt clusters: only at potentials where the OH species are adsorbed at the edge between the Pt nanocluster and the gold support, the oxidation of the carbon monoxide on the Pt nanoparticles takes place.Catalysis and Surface Chemistr

One-year outcomes after transcatheter insertion of an interatrial shunt device for the management of heart failure with preserved ejection fraction

Background—Heart failure with preserved ejection fraction has a complex pathophysiology and remains a therapeutic challenge. Elevated left atrial pressure, particularly during exercise, is a key contributor to morbidity and mortality. Preliminary analyses have demonstrated that a novel interatrial septal shunt device that allows shunting to reduce the left atrial pressure provides clinical and hemodynamic benefit at 6 months. Given the chronicity of heart failure with preserved ejection fraction, evidence of longer-term benefit is required. Methods and Results—Patients (n=64) with left ventricular ejection fraction ≥40%, New York Heart Association class II–IV, elevated pulmonary capillary wedge pressure (≥15 mm Hg at rest or ≥25 mm Hg during supine bicycle exercise) participated in the open-label study of the interatrial septal shunt device. One year after interatrial septal shunt device implantation, there were sustained improvements in New York Heart Association class (P<0.001), quality of life (Minnesota Living with Heart Failure score, P<0.001), and 6-minute walk distance (P<0.01). Echocardiography showed a small, stable reduction in left ventricular end-diastolic volume index (P<0.001), with a concomitant small stable increase in the right ventricular end-diastolic volume index (P<0.001). Invasive hemodynamic studies performed in a subset of patients demonstrated a sustained reduction in the workload corrected exercise pulmonary capillary wedge pressure (P<0.01). Survival at 1 year was 95%, and there was no evidence of device-related complications. Conclusions—These results provide evidence of safety and sustained clinical benefit in heart failure with preserved ejection fraction patients 1 year after interatrial septal shunt device implantation. Randomized, blinded studies are underway to confirm these observations

Polymer of Intrinsic Microporosity Induces Host-Guest Substrate Selectivity in Heterogeneous 4-Benzoyloxy-TEMPO-Catalysed Alcohol Oxidations

The free radical 4-benzoyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl (4B-TEMPO) is active as an electrocatalyst for primary alcohol oxidations when immobilised at an electrode surface and immersed into an aqueous carbonate buffer solution. In order to improve the catalytic process, a composite film electrode is developed based on (i) carbon microparticles of 2–12 μm diameter to enhance charge transport and (ii) a polymer of intrinsic microporosity (here PIM-EA-TB with a BET surface area of 1027 m2 g−1). The latter acts as a highly rigid molecular framework for the embedded free radical catalyst with simultaneous access to aqueous phase and substrate. The resulting mechanism for the oxidation of primary alcohols is shown to switch in reaction order from first to zeroth with increasing substrate concentration consistent with a kinetically limited process with competing diffusion of charge at the polymer layer-electrode interface (here the “LEk” case in Albery-Hillman notation). Reactivity optimisation and screening for a wider range of primary alcohols in conjunction with DFT-based relative reactivity correlation reveals substrate hydrophobicity as an important factor for enhancing catalytic currents. The PIM-EA-TB host matrix is proposed to control substrate partitioning and thereby catalyst reactivity and selectivity