Potassium-based algorithm allows correction for the hematocrit bias in quantitative analysis of caffeine and its major metabolite in dried blood spots

Although dried blood spot (DBS) sampling is increasingly receiving interest as a potential alternative to traditional blood sampling, the impact of hematocrit (Hct) on DBS results is limiting its final breakthrough in routine bioanalysis. To predict the Hct of a given DBS, potassium (K+) proved to be a reliable marker. The aim of this study was to evaluate whether application of an algorithm, based upon predicted Hct or K+ concentrations as such, allowed correction for the Hct bias. Using validated LC-MS/MS methods, caffeine, chosen as a model compound, was determined in whole blood and corresponding DBS samples with a broad Hct range (0.18-0.47). A reference subset (n = 50) was used to generate an algorithm based on K+ concentrations in DBS. Application of the developed algorithm on an independent test set (n = 50) alleviated the assay bias, especially at lower Hct values. Before correction, differences between DBS and whole blood concentrations ranged from -29.1 to 21.1 %. The mean difference, as obtained by Bland-Altman comparison, was -6.6 % (95 % confidence interval (CI), -9.7 to -3.4 %). After application of the algorithm, differences between corrected and whole blood concentrations lay between -19.9 and 13.9 % with a mean difference of -2.1 % (95 % CI, -4.5 to 0.3 %). The same algorithm was applied to a separate compound, paraxanthine, which was determined in 103 samples (Hct range, 0.17-0.47), yielding similar results. In conclusion, a K+-based algorithm allows correction for the Hct bias in the quantitative analysis of caffeine and its metabolite paraxanthine

Hexagonal-boron nitride substrates for electroburnt graphene nanojunctions

We examine the effect of a hexagonal boron nitride (hBN) substrate on electron transport through graphene nanojunctions just before gap formation. Junctions in vacuum and on hBN are formed using classical molecular dynamics to create initial structures, followed by relaxation using density functional theory. We find that the hBN only slightly reduces the current through the junctions at low biases. Furthermore due to quantum interference at the last moments of breaking, the current though a single carbon filament spanning the gap is found to be higher than the current through two filaments spanning the gap in parallel. This feature is present both in the presence of absence of hBN

Electron and heat transport in porphyrin-based single-molecule transistors with electro-burnt graphene electrodes

We have studied the charge and thermal transport properties of a porphyrin-based single-molecule transistor with electro-burnt graphene electrodes (EBG) using the nonequilibrium Green’s function method and density functional theory. The porphyrin-based molecule is bound to the EBG electrodes by planar aromatic anchor groups. Due to the efficient π–π overlap between the anchor groups and graphene and the location of frontier orbitals relative to the EBG Fermi energy, we predict HOMO-dominated transport. An on–off ratio as high as 150 is predicted for the device, which could be utilized with small gate voltages in the range of ±0.1 V. A positive thermopower of +280 μV/K is predicted for the device at the theoretical Fermi energy. The sign of the thermopower could be changed by tuning the Fermi energy. By gating the junction and changing the Fermi energy by +10 meV, this can be further enhanced to +475 μV/K. Although the electrodes and molecule are symmetric, the junction itself can be asymmetric due to different binding configurations at the electrodes. This can lead to rectification in the current–voltage characteristic of the junction

Oligoyne molecular junctions for efficient room temperature thermoelectric power generation

Understanding phonon transport at a molecular scale is fundamental to the development of high-performance thermoelectric materials for the conversion of waste heat into electricity. We have studied phonon and electron transport in alkane and oligoyne chains of various lengths and find that, due to the more rigid nature of the latter, the phonon thermal conductances of oligoynes are counterintuitively lower than that of the corresponding alkanes. The thermal conductance of oligoynes decreases monotonically with increasing length, whereas the thermal conductance of alkanes initially increases with length and then decreases. This difference in behavior arises from phonon filtering by the gold electrodes and disappears when higher-Debye-frequency electrodes are used. Consequently a molecule that better transmits higher-frequency phonon modes, combined with a low-Debye-frequency electrode that filters high-energy phonons is a viable strategy for suppressing phonon transmission through the molecular junctions. The low thermal conductance of oligoynes, combined with their higher thermopower and higher electrical conductance lead to a maximum thermoelectric figure of merit of ZT = 1.4, which is several orders of magnitude higher than that of alkanes

Enhancing the thermoelectric figure of merit in engineered graphene nanoribbons

We demonstrate that thermoelectric properties of graphene nanoribbons can be dramatically improved by introducing nanopores. In monolayer graphene, this increases the electronic thermoelectric figure of merit ZTe from 0.01 to 0.5. The largest values of ZTe are found when a nanopore is introduced into bilayer graphene, such that the current flows from one layer to the other via the inner surface of the pore, for which values as high as ZTe = 2.45 are obtained. All thermoelectric properties can be further enhanced by tuning the Fermi energy of the leads

Target detection through quantum illumination

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, February 2012."February 2012." Cataloged from PDF version of thesis.Includes bibliographical references (p. 69-70).Classical target detection can suffer large error probabilities in noisy and lossy environments when noise photons are mistaken for signal photons reflected from an object. It has been shown theoretically that the correlation between entangled photons can be used to better discriminate between the signal photons reflected by an object and noise photons, thus reducing the probability of error [13, 15, 17, 7, 6]. This thesis presents the first experimental implementation of target detection enhanced by quantum illumination (QI). Nondegenerate, time entangled signal and idler beams are created through Type-O spontaneous parametric downconversion (SPDC). The signal is attenuated and combined with large levels of noise. The signal is phase modulated to improve the observation by shifting it from DC to 16 kHz. The return signal and idler are recombined in an optical parametric amplifier (OPA) which captures the phase correlation between the two beams. It is found that only 10% of the total signal and idler photons interact at the OPA due to the multi-mode nature of the SPDC emission which does not match the pump spatial mode and thus experience lower gains at the OPA. Considering only the power interacting at the OPA, the signal-to-noise ratio (SNR) of QI agrees with the theoretical model.by Sara L. Mouradian.M.Eng

Breakdown of Curly Arrow Rules in Anthraquinone

Understanding and controlling quantum interference QI in single molecules is fundamental to the development of QI based single molecule electronics. Over the past decade, simple rules such as counting rules, curly arrow rules, circuit rules and more recently magic ratio rules have been developed to predict QI patterns in polycyclic aromatic hydrocarbons. These rules have been successful in explaining observed electronic transport properties of molecular junctions and provide helpful design tools for predicting properties of molecules before their synthesis. Curly arrow rules are widely used by chemists, material scientists and physicists to predict destructive QI. Here we examine the validity of curly arrow rules in fully conjugated anthracene and dihydroxyanthracene, cross‐conjugated anthraquinone and broken conjugated dihydroanthracene attached to graphene or gold electrodes through pi‐pi stacking or thiol and Au‐C anchors. For the first time, we demonstrate that curly arrow rules break down in molecular junctions formed by cross‐conjugated anthraquinone. In contrast with the destructive QI predicted by curly arrow rules for a meta connected anthraquinone core, we demonstrate that QI is constructive. This behavior is independent of the choice of electrode material or anchor groups. This is significant, because by changing the redox state of meta connected dihydroxyanthracene to form meta connected anthraquinone, the conductance of the junction increases by couple of orders of magnitude due to the cross over form constructive to destructive QI. This opens new avenues for realization of quantum interference based single molecule switches

La singularité de la prose mythologique de Madame Flore dans la Pugnition de l'amour contempné (1540) : étude sur l'antérotisme floréen

Cette étude montre en quoi la prose mythologique de madame Flore est singulière en étudiant l'antérotisme de La Pugnition de l'Amour contempné (1540). Elle constitue la première recherche qui porte spécifiquement sur cet état de l'oeuvre plutôt que sur les Comptes amoureux (s. d.) et postule que, des deux états de l'oeuvre de madame Flore, les Comptes amoureux représentent le second état à l'encontre de ce qu'une certaine critique affirme. Ce mémoire apporte un argument de poids en faveur de la préseance de la publication de La Pugnition de l'Amour contempné (1540) sur les Comptes amoureux [1542] en raison de la cohérence de l'idéologie amoureuse antérotique qui traverse La Pugnition et qui fait justement défaut aux contes plus disparates des Comptes amoureux, ouvrage davantage préoccupé par la dénonciation de l'« impareil » mariage entre vieux barbons et jeunes tendrons. Ce mémoire, qui cherche aussi à mettre au jour les lignes directrices de la pensée mythologique de celle qui dit les désirs des femmes émanant d'une société chrétienne qui voudrait les voir chastes et pudiques, se subdivise en quatre chapitres. Le premier étudie le langage mythologique qui voit le jour à la Renaissance, sous le règne de François 1er. Le deuxième retrace les origines gréco-romaines du concept d'Anteros ainsi que des traditions qui en découlent. Le troisième analyse trois traditions antérotiques à la Renaissance avec leurs antécédents médiévaux. Ces trois traditions sont: l'antérotisme vengeur des amours méprisées, l'antérotisme contre l'amour humain et l'antérotisme de l'amour réciproque (ou Contramour). Le quatrième chapitre, quant à lui, étudie l'antérotisme des quatre contes et des parties lacunaires de La Pugnition pour montrer que, d'un côté, ce premier état de l'oeuvre présente la tradition antérotique en faisant du dieu Amour un dieu vengeur des amours méprisées, associant ainsi sa divinité à Anteros, et que de l'autre, il présente la tradition contre l'amour humain non pas sous la forme du dieu Amour, mais sous la forme d'un personnage, Cebille, qui se refuse obstinément à l'amour.\ud L'étude que nous présentons ici redonnera, c'est notre souhait, envie à la critique contemporaine de réétudier pour elle-même et dans une autre perspective l'édition souvent méprisée (parce que considérée incomplète) de La Pugnition et, par extension, motivera quelques férus de littérature renaissante à s'intéresser à ce courant quelque peu trop méconnu par la critique contemporaine qu'est l'antérotisme alors qu'Anteros vivait sous diverses formes sous la plume des poètes et prosateurs de la Renaissance. À la lumière de cette étude, il sera, pour d'autres aimants du sujet floréen, à nouveau opportun de chercher à savoir qui, de tous les renaissants érudits et amateurs d'Anteros, pourrait se cacher derrière le pseudonyme probable de madame Flore. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : Madame Jane ou Jeanne Flore, La Pugnition de l'Amour contempné, Comptes amoureux, Langage, Mythologie, Antérotisme, Anteros, Eros, Contramour, Amour, Marguerite de Navarre, Renaissance, XVIe siècle

Magic ratios for connectivity-driven electrical conductance of graphene-like molecules

Experiments using a mechanically-controlled break junction and calculations based on density functional theory demonstrate a new magic ratio rule (MRR),which captures the contribution of connectivity to the electrical conductance of graphene-like aromatic molecules. When one electrode is connected to a site i and the other is connected to a site i' of a particular molecule, we assign the molecule a magic integer Mii'. Two molecules with the same aromatic core, but different pairs of electrode connection sites (i,i' and j,j' respectively) possess different magic integers Mii' and Mjj'. Based on connectivity alone, we predict that when the coupling to electrodes is weak and the Fermi energy of the electrodes lies close to the centre of the HOMO-LUMO gap, the ratio of their conductances is equal to (Mii' /Mjj')2. The MRR is exact for a tight binding representation of a molecule and a qualitative guide for real molecules