On the Validity and Applicability of Models of Negative Capacitance and Implications for MOS Applications

The observation of room temperature sub-60 mV/dec subthreshold slope (SS) in MOSFETs with ferroelectric (FE) layers in the gate stacks or in series with the gate has attracted much attention. Recently, we modeled this effect in the framework of a FE polarization switching model. However, there is a large amount of literature attributing this effect to a stabilization of quasi-static (QS) negative capacitance (NC) in the FE. The technological implications of a stabilized non-switching (NS) QSNC model vs a FE switching model are vastly different; the latter precluding applications to sub-60 mV/dec SS scaled CMOS due to speed limitations and power dissipated in switching. In this letter, we provide a thorough analysis assessing the foundations of models of QSNC, identifying which specific assumptions (ansatz) may be unlikely or unphysical, and analyzing their applicability. We show that it is not reasonable to expect QSNC for two separate capacitors connected in series (with a metal plate between dielectric (DE) and FE layers). We propose a model clarifying under which conditions a QS "apparent NC" for a FE layer in a FE-DE bi-layer stack may be observed, quantifying the requirements of strong interface polarization coupling in addition to capacitance matching. In this regime, our model suggests the FE layer does not behave as a NC layer, simply, the coupling leads to both the DE and FE behaving as high-k DE with similar permittivities. This may be useful for scaled EOT devices but does not lead to sub-60 mV/dec SS.Comment: Version published in Appl. Phys. Let

Antioxidant Capacities and Phenolic Levels of Different Varieties of Serbian White Wines

The biologically active compounds in wine, especially phenolics, are responsible for reduced risk of developing chronic diseases (cardiovascular disrease, cancer, diabetes, etc.), due to their antioxidant activities. We determined the contents of total phenolics (TP) and total flavonoids (TF) in selected Serbian white wines by colorimetric methods. Total antioxidant activity (TAA) of the white wines was analyzed using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity assay. Međaš beli had the highest content of TP, TF and TAA. The radical scavenging capacity (RSC) and total antioxidant activity (TAA) of white wines were 15.30% and 1.055 mM Trolox equivalent, respectively. Total phenolic (TP) and total flavonoid (TF) contents in white wines ranged from 238.3 to 420.6 mg gallic acid equivalent per L of wines and 42.64 to 81.32 mg catechin equivalent per L of wines, respectively. A high and significant correlation between antioxidant activity and total phenolic content was determined in wines (R2 = 0.968, p < 0.01). For the individual polyphenols determination we used a high performance liquid chromatography (HPLC)-diode array detection (DAD) technique. The majority of white wine polyphenols was represent by four hydroxycinnamic acids (HCAs)

Cosmic string parameter constraints and model analysis using small scale Cosmic Microwave Background data

We present a significant update of the constraints on the Abelian Higgs cosmic string tension by cosmic microwave background (CMB) data, enabled both by the use of new high-resolution CMB data from suborbital experiments as well as the latest results of the WMAP satellite, and by improved predictions for the impact of Abelian Higgs cosmic strings on the CMB power spectra. The new cosmic string spectra (presented in a previous work) were improved especially for small angular scales, through the use of larger Abelian Higgs string simulations and careful extrapolation. If Abelian Higgs strings are present then we find improved bounds on their contribution to the CMB anisotropies, f10< 0.095, and on their tension, G\mu< 0.57 x 10^-6, both at 95% confidence level using WMAP7 data; and f10 < 0.048 and G\mu < 0.42 x 10^-6 using all the CMB data. We also find that using all the CMB data, a scale invariant initial perturbation spectrum, ns=1, is now disfavoured at 2.4\sigma\ even if strings are present. A Bayesian model selection analysis no longer indicates a preference for strings.Comment: 8 pages, 3 figures; Minor corrections, matches published versio

Post-peak fracture behavior during direct shear tests of rock joints

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Oxygen Transport in Tissue Engineering Systems: Cartilage and Myocardium

Efficient transport of oxygen is one of the main requirements in tissue engineering systems in order to avoid cell death in the inner tissue regions and support uniform tissue regeneration. In this paper, we review approaches to design of tissue engineering systems with adequate oxygen delivery for cultivation of cartilage and myocardium, two distinctly different tissue types with respect to the tissue structure and oxygen requirements. Mathematical modeling was used to support experimental results and predict oxygen transport within the cultivated tissues and correlate it to the cell response and tissue properties

Immobilization of cells by electrostatic droplet generation: a model system for potential application in medicine

The process of electrostatic extrusion as a method for cell immobilization was investigated that could be used for potential applications in medicine. An attempt was made to assess the effects of cell addition and polymer concentration on the overall entrapment procedure, ie, on each stage of immobilization: polymer-cell suspension rheological characteristics, electrostatic extrusion process, and the process of gelation. The findings should contribute to a better understanding of polymer–cell interactions, which could be crucial in possible medical treatments. Alginate–yeast was used as a model system for carrier-cells. The electrostatic extrusion was considered as a complex two-phase flow system and the effects of cell and alginate concentrations on the resulting microbead size and uniformity were assessed. Under investigated conditions, microbeads 50–600 μm in diameter were produced and the increase in both alginate and cell concentrations resulted in larger microbeads with higher standard deviations in size. We attempted to rationalize the findings by rheological characterization of the cell–alginate suspensions. Rheological characterization revealed non-Newtonian, pseudoplastic behavior of cell-alginate suspensions with higher viscosities at higher alginate concentrations. However, the presence of cells even at high concentrations (5×108 and 1×109 cells/mL) did not significantly affect the rheological properties of Na-alginate solution. Lastly, we investigated the kinetics of alginate gelation with respect to the quantity of Ca2+ ions and cell presence. The gelation kinetics were examined under conditions of limited supply with Ca2+ ions, which can be essential for immobilization of highly sensitive mammalian cells that require minimal exposure to CaCl2 solution. The molar ratio of G units to Ca2+ ions of 3.8:1 provided complete crosslinking, while the increase in alginate concentration resulted in prolonged gelation times but higher strength of the resulting gel. The cell presence decreased the rate of network formation as well as the strength of the obtained Ca-alginate hydrogel

Modeling Single Electron Transfer in Si:P Double Quantum Dots

Solid-state systems such as P donors in Si have considerable potential for realization of scalable quantum computation. Recent experimental work in this area has focused on implanted Si:P double quantum dots (DQDs) that represent a preliminary step towards the realization of single donor charge-based qubits. This paper focuses on the techniques involved in analyzing the charge transfer within such DQD devices and understanding the impact of fabrication parameters on this process. We show that misalignment between the buried dots and surface gates affects the charge transfer behavior and identify some of the challenges posed by reducing the size of the metallic dot to the few donor regime.Comment: 11 pages, 7 figures, submitted to Nanotechnolog

Morphometric analysis of mandibular canal: clinical aspects

Results of morphometric analysis of the mandibular canal (MC), carried out on 105 conserved mandibles, 70 being dentate and 35 edentate, was performed. The analysis was carried out on consecutive sections, at mutual intervals of 0.5 cm. In the mandibular ramus sections were carried out obliquely, approximately in the frontal plane, and horizontally, from mandibular foramen to the lowest region of the vertical part of the MC (all together two sections). In the mandibular corpus, consecutive transversal sections were carried out between existing teeth, or at mutual intervals of 0.5 cm in edentate regions.The obtained results pointed out the very close relationship between the MC and lingual cortical plate of the mandibular ramus. In its horizontal part, the average diameter of the MC was 2.6 mm. It was situated more lingually in the molar region; towards the front, it approached the vestibular cortical plate, being closest to it in the region of the second premolar. Similar relationships of the MC and both cortical plates existed in edentate jaws. Relationships of the MC and tooth root apices varied; however, the MC was closest to the apices of the third molar. Mesially from the mental foramen, a clearly defined incisive canal was present in 92% of the dentale mandibles, but only in 31% of the edentate ones. The nearest to the incisive canal was the apex of the first premolar.The authors point out the importance of presented results in everyday practice, especially in oral and maxillofacial surgery. Having in mind the existing relationship between the MC and neighbouring structures, it is possible to avoid the injury of its content during several oral surgical procedures in mandibular ramus and corpus.L’analyse morphométrique du canal mandibulaire (CM) a été faite sur 105 mandibules conservées. Parmices mandibules, 70 étaient partiellement édentées et 35 totalement édentées. Les distances du CM de la couche compacte osseuse de la mandibule et des apex des racines dentaires ont été mesurées sur les coupes successives pratiquées à une distance de 0,5 cm. Dans la région de la branche montante mandibulaire les coupes successives ont été pratiquées suivant le plan horizontal, de l'orifice postérieur du canal mandibulaire à la terminaison de la partie verticale du CM. La région du corps mandibulaire a été traitée par des coupes verticales. Ces sections ont été faites successivement à travers l’espace entre chaque deux dents ou à une distance de 0,5 cm dans les régions édentées.Les résultats obtenus montrent que le CM se dirige obliquement de haut en bas et en avant, très proche de la lame osseuse linguale. Dans la partie horizontale son diamètre est de 2,6 mm en moyenne. Dans la région des dents molaires le CM est très proche de la lame osseuse linguale; en cheminant en avant, le CM s’approche de la lame osseuse buccale dont il est le plus proche dans la région de la P2. Dans les mandibules édentées, le CM a des rapports semblables.La distance du CM des apex des racines dentaires est variable, pourtant il est le plus proche des apex des racines de la M3. Mésialement du trou mentonnier, le canal incisif était clairement individualisé dans 92% des mandibules avec la denture conservée, et dans 31% des mandibules édentées. La première prémolaire était la plus proche du canal incisif.Les auteurs montrent l’importance des résultats présentés pour la stomatologie clinique, surtout pour la chirurgie orale et maxillofaciale. Compte tenu des rapports du CM avec les structures voisines on peut éviter des lésions de son contenu au cours de certaines interventions chirurgicales sur la branche montante et sur le corps de la mandibule