Search results for "Screen"
showing 10 items of 1374 documents
Stereocontrol in Diphenylprolinol Silyl Ether Catalyzed Michael Additions : Steric Shielding or Curtin-Hammett Scenario?
2017
The enantioselectivity of amine-catalyzed reactions of aldehydes with electrophiles is often explained by simple steric arguments emphasizing the role of the bulky group of the catalyst that prevents the approach of the electrophile from the more hindered side. This standard steric shielding model has recently been challenged by the discovery of stable downstream intermediates, which appear to be involved in the rate-determining step of the catalytic cycle. The alternative model, referred to as Curtin-Hammett scenario of stereocontrol, assumes that the enantioselectivity is related to the stability and reactivity of downstream intermediates. In our present computational study, we examine th…
Are credit screening contracts designed for men?
2022
AbstractAccess to credit is key to succeed in business. Theoretical models of credit under asymmetric information classify borrowers and grant or deny credit, typically based on incentive-compatible contracts with collateral. However, if women are particularly risk averse, female borrowers may be wrongly classified and denied credit. We conduct in three countries a laboratory experiment to study this systematic gender difference. Results show that incentive-compatible contracts with collateral fail to disclose women’s private information, while disclosing men’s private information. We suggest that banks should incorporate the gender difference in risk attitudes to avoid the glass ceiling in…
Multicellular tumor spheroids: an underestimated tool is catching up again.
2009
The present article highlights the rationale, potential and flexibility of tumor spheroid mono- and cocultures for implementation into state of the art anti-cancer therapy test platforms. Unlike classical monolayer-based models, spheroids strikingly mirror the 3D cellular context and therapeutically relevant pathophysiological gradients of in vivo tumors. Some concepts for standardization and automation of spheroid culturing, monitoring and analysis are discussed, and the challenges to define the most convenient analytical endpoints for therapy testing are outlined. The potential of spheroids to contribute to either the elimination of poor drug candidates at the pre-animal and pre-clinical …
A convolutional neural network for virtual screening of molecular fingerprints
2019
In the last few years, Deep Learning (DL) gained more and more impact on drug design because it allows a huge increase of the prediction accuracy in many stages of such a complex process. In this paper a Virtual Screening (VS) procedure based on Convolutional Neural Networks (CNN) is presented, that is aimed at classifying a set of candidate compounds as regards their biological activity on a particular target protein. The model has been trained on a dataset of active/inactive compounds with respect to the Cyclin-Dependent Kinase 1 (CDK1) a very important protein family, which is heavily involved in regulating the cell cycle. One qualifying point of the proposed approach is the use of molec…
Unusual resistive states of multiband superconductors in the effective field theory approach
2020
Starting from the microscopic approach based on multiband Keldysh-Usadel kinetic theory we derive the minimal field-theoretical model equivalent to the time-dependent Ginzburg-Landau theory. We discuss the properties of resistive states determined by the ratio of electric field relaxation length to the superconducting coherence length. In contrast to the well-studied single-band systems we find that this ratio can vary in wide limits in multiband superconductors. As a result, the properties of resistive states in multiband superconductors can be tuned by the microscopic parameters such as the ratio of diffusion coefficients and pairing constants in different bands. As an example we consider…
Resistive state triggered by vortex entry in YBa 2 Cu 3 O 7−δ nanostructures
2014
We have realized YBa2Cu3O7-delta nanowires and nano Superconducting Quantum Interference Devices (nanoSQUID). The measured temperature dependence of the wire resistances below the superconducting transition temperature has been analyzed using a thermally activated vortex entry model valid for wires wider than the superconducting coherence length. The extracted zero temperature values of the London penetration depth, lambda(0) similar or equal to 270 +/- 15 nm, are in good agreement with the value obtained from critical current modulations as a function of an externally applied magnetic field in a nanoSQUID implementing two nanowires.
Phase Slip Phenomena in Ultra-Thin Superconducting Wires
2006
We present results on phase-slip phenomena in a superconducting wire which can be considered as quasi-one dimensional (1D) if its characteristic transverse dimension \( \sqrt \sigma\) (√ being the cross section) is smaller than the coherence length Λ(T). The shape of the bottom part of the resistive transition R(T) of a 1D superconducting strip is described by the model of phase slips activation. If the wire is infinitely long, then there is always a finite probability that a small part of the sample is instantly driven normal.
Resistive State of Superconductor-Ferromagnet-Superconductor Josephson Junctions in the Presence of Moving Domain Walls
2019
We describe resistive states of the system combining two types of orderings---a superconducting and a ferromagnetic one. It is shown that in the presence of magnetization dynamics such systems become inherently dissipative and in principle cannot sustain any amount of the superconducting current because of the voltage generated by the magnetization dynamics. We calculate generic current-voltage characteristics of a superconductor-ferromagnet-superconductor Josephson junction with an unpinned domain wall and find the low-current resistance associated with the domain wall motion. We suggest the finite slope of Shapiro steps as the characteristic feature of the regime with domain wall oscillat…
Experimental Study of the Fluctuation-Governed Resistive State in Quasi-One-Dimensional Superconductors
2011
Physical properties of quasi-one-dimensional superconducting channels (nanowires) can differ significantly from those of bulk superconductors. The reason behind is the impact of thermal and quantum fluctuations. In the particular case of resistive measurements the fluctuations may significantly broaden the superconducting transition R(T). Here we review the activities in the field with main emphasis on experiment, while brief theoretical background is also presented.
Low-Frequency Imaginary Impedance at the Superconducting Transition of 2H - NbSe2
2020
The superconducting transition leads to a sharp resistance drop in a temperature interval that can be a small fraction of the critical temperature ${T}_{c}$. A superconductor exactly at ${T}_{c}$ is thus very sensitive to all kinds of thermal perturbation, including the heat dissipated by the measurement current. We show that the interaction between electrical and thermal currents leads to a sizable imaginary impedance at frequencies of the order of tens of hertz at the resistive transition of single crystals of the layered material $2H$-${\mathrm{Nb}\mathrm{Se}}_{2}$. We explain the result using models developed for transition-edge sensors. By measuring under magnetic fields and at high cu…