A flow-through microfluidic chip for continuous dielectrophoretic separation of viable and non-viable human T-cells

Effective methods for rapid sorting of cells according to their viability are critical in T cells based therapies to prevent any risk to patients. In this context, we present a novel microfluidic device that continuously separates viable and non-viable T-cells according to their dielectric properties. A dielectrophoresis (DEP) force is generated by an array of castellated microelectrodes embedded into a microfluidic channel with a single inlet and two outlets; cells subjected to positive DEP forces are drawn toward the electrodes array and leave from the top outlet, those subjected to negative DEP forces are repelled away from the electrodes and leave from the bottom outlet. Computational fluid dynamics is used to predict the device separation efficacy, according to the applied alternative current (AC) frequency, at which the cells move from/to a negative/positive DEP region and the ionic strength of the suspension medium. The model is used to support the design of the operational conditions, confirming a separation efficiency, in terms of purity, of 96% under an applied AC frequency of 1.5 × 10⁶ Hz and a flow rate of 20 μl/h. This work represents the first example of effective continuous sorting of viable and non-viable human T-cells in a single-inlet microfluidic chip, paving the way for lab-on-a-chip applications at the point of need.     

Thermal,chemical, and mineralogical characterization of ceramic tobacco pipes from Cyprus

This study is focused on simultaneous thermoanalytical investigations by TG/DTG-DTA technique applied for characterization of samples collected from archaeological site of Nicosia, Cyprus, dating to seventeenth century and gave new information on the firing technology. The ceramic samples derived from Ottomanic tobacco pipes were characterized by the related techniques such as X-ray powder diffraction for the mineralogical composition, and inductively coupled plasma-atomic emission spectrometry and micro-X-ray fluorescence spectroscopic analysis for the chemical content. It was found that they consisted mainly of quartz, calcite, feldspars, and micas. For the majority of the investigated ceramic samples, the thermal behavior investigation collaborates with their mineralogical findings, and resulted to the firing temperature at ~700 °C, due to the existence of calcite. Only in two samples with very high content in quartz, absence of calcite, low amounts of adsorbed water and of total mass loss, and absence of micas, the firing process resulted up to 1000 °C.     

A study on the utility of bismuth-film electrodes for the determination of In(III) in the presence of Pb(II) and Cd(II) by square wave anodic stripping voltammetry

This work is an investigation into the utility of bismuth-film electrodes (BiFEs) for the determination of indium in the presence of cadmium and lead by square wave anodic stripping voltammetry (SWASV). The purpose of this study was to demonstrate that, after judicious choice of the associated chemical and instrumental conditions, it is possible to achieve satisfactory separation of the relevant stripping peak and, thus, to determine simultaneously trace concentrations of cadmium, lead and indium. It was conclusively demonstrated that a BiFE performed better than the equivalent mercury-film electrode (MFE) in this particular application.     

Hybrid artificial neural networks for efficient valuation of real options and financial derivatives

A hybrid valuation methodology is proposed and tested for improving the efficiency of contingent claims pricing by combining Artificial Neural Networks (ANN) and conventional parametric option pricing techniques. With one application on financial derivatives and one on real options the methods superiority is demonstrated. The resulting efficiency is instrumental for real time applications.MSC code: 90-08 Acknowledgements: Both authors are thankful for partial financial support to the HERMES European Center of Excellence on Computational Finance and Economics of the University of Cyprus and a University of Cyprus grant for research in ANNs and Derivatives, and to the anonymous referees for their helpful comments and discussions.     

On the spectrum of the Laplacian

In this article we prove a generalization of Weyl’s criterion for the essential spectrum of a self-adjoint operator on a Hilbert space. We then apply this criterion to the Laplacian on functions over open manifolds and get new results for its essential spectrum.     

In search for mixed transition metal/lanthanide single-molecule magnets: Synthetic routes to NiII/TbIII and NiII/DyIII clusters featuring a 2-pyridyl oximate ligand

Employing the mononuclear complex [Ni{(py)C(Me)NO}₂{(py)C(Me)NOH}] (1) as ‘ligand’ [(py)C(Me)NOH = methyl 2-pyridyl ketone oxime], the use of the ‘metal complexes as ligands’ approach has led to the synthesis of the mixed Ni^II/Ln^III complexes [NiTb{(py)C(Me)NO}₂(NO₃)₃{(py)C(Me)NOH}] (2), [Ni₂Ln₂{(py)C(Me)NO}₆(NO₃)₄] (Ln = Dy, 3; Ln = Tb, 4) and [Ni₂Tb{(py)C(Me)NO}₆](NO₃) (5). The structures of 2, 3, and 5, and the magnetic properties of 2 and 5 are briefly discussed.     

On conditions for optimality in least pth approximation withp → ∞

This paper presents a theoretical discussion of the necessary and sufficient conditions for optimality in generalized nonlinear leastpth approximation problems forp . In the limit, the conditions for a minimax approximation are derived, as is to be expected. Numerical examples involving the modeling of a linear time-invariant fourth-order system by a second-order model and the design of quarter-wave transmission-line transformers illustrate the results.This work was supported by the National Research Council of Canada under Grant No. A7239 and by a Frederick Gardner Cottrell Grant from the Research Corporation. This paper was presented at the 9th Annual Allerton Conference on Circuit and System Theory, Urbana, Illinois, October 6–8, 1971. The authors thank Mrs. J. R. Popovi for helping to correct Example 4.1.     

DFT and experimental investigation of catecholate derivatives of benzoic acid and pyridine

DFT calculations, at the B3LYP/TZVP level of theory for pyrocatechuic acid (2,3-dihydroxybenzoic acid, 2,3-DHBA), 2,3-dihydroxy-pyridine 2,3-DHPY and their ionized and oxidized forms, have been performed, in combination with experimental data. ¹H, ¹³C, 2D COSY NMR, IR and electronic spectra were coupled to the theoretical calculations. The geometrical parameters were checked by reported crystallographic data. The neutral form of pyrocatechuic acid is the most stable, regarding its ionized (mono-, di- or tri-anions) and oxidized ([2,3-DHBA-sqH]⁻, [2,3-DHBA-sq]²⁻, [2,3-DHBA-q]⁻) species. The most stable conformer 2,3-DHBA-H₃ displays the COOH– group co-planar to the catechol ring, hydrogen bonded with OH(2). In the [2,3-DHBA-H₂]⁻ the stable conformer shows the presence of protonated COOH, while OH(2) is ionized. The tri-anion is the form of 2,3-DHBA with the highest energy. Among the protonated semiquinone radical forms [2,3-DHBA-sqH]⁻, more stable is the OH(3)-oxidized, cited 21.3 kcal/mol lower in energy from the OH(2)-oxidized; in this latter the COO⁻ group lies perpendicular to the benzene ring. The same calculation procedure fitted on the oxygenated [2,3-DHBA-H-O₂]²⁻ shows a weak π-bonding between O(2) and dioxygen, strongly H–bonded to OH(3), while the C(2)–O bond order increases. The different way of 2,3-DHBA oxidation parallels the different, from 3,4-isomer, degradation products. Our DFT calculations show that the keto/enol tautomeric forms of the neutral 2,3-DHPY-H₂ differ by 5.02 kcal/mol. Both species give, upon ionization, the [2,3-DHPY-H]⁻ with the OH(2) deprotonated. The electronic density distribution of [2,3-DHPY-q] justifies further reactions (degradation or dienic addition) as experimentally observed.