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Role of Tensile Stress in DNA Nanoresonators for Epigenetic Studies
No full textThe evaluation of epigenetic features such as DNA methylation is becoming increasingly important in many biochemical processes like gene expression and transcription as well as in several diseases like schizophrenia or diabetes. Here, we report that self-assembled nanomechanical resonators entirely composed of DNA molecules can be used to explore gross changes in DNA methylation levels (0-25-50%), while careful control of tensile stress is needed to reduce the variability of resonance frequency for rigorous quantification. The effect of the tensile stress retained by the suspended DNA nanoresonators on the application of the technique is extensively explored using a combination of laser Doppler vibrometry and atomic force spectroscopy. DNA nanoresonators are real-time, label-free sensors and could avoid chemical functionalization and sample amplification. Therefore, they may represent in the future a key complementary routine tool for global DNA methylation analysis needed to evaluate the consequences of environmental stresses on the human genome
Speed of sound measurements and derived third and fourth acoustic virial coefficients of supercritical neon
No full textWe report comprehensive and accurate measurements of the speed of sound in neon. These measurements were carried out by a double-path-length pulse-echo technique and cover the temperature range between 200 K and 420 K with pressures up to 100 MPa. The standard uncertainties are 1.9 mK in temperature, 22 parts in 106 in pressure and 35 parts in 106 in speed of sound. The third and fourth acoustic virial coefficients of neon were derived from the speed of sound data in the temperature range of the measurements by fitting a fourth-order acoustic virial expansion in pressure with the second acoustic virial coefficient constrained from first-principles calculations. To support our claimed uncertainty, we determined the ratio M / γ 0 between the molar mass M and the ideal-gas heat capacity ratio γ 0 of the neon sample with a relative standard uncertainty of 7.7 parts in 106 by additional speed of sound measurements using a spherical resonator at 273.16 K
Measurement Repeatability of a Supercapacitor Equivalent Circuit Parameters
No full textThe determination of the equivalent parameters of a supercapacitor requires the galvanostatic measurement of a charge and self-discharge cycle. If a more general determination is needed than that on the single cycle, it is necessary to take into account the repeatability of the charging and self-discharging cycles. A cycle for determining the parameters can also extend over a few hours for larger supercapacitors, also considering the time needed to identify the parameters. Therefore, having a large set of dozens of cycles including the parameters determination is definitely a time-consuming procedure. In this work, an efficient method for the repeatability assessment of the equivalent circuit parameters is proposed; this approach relies on a limited set of experimental curves and on a single parameter identification process
Spectrum of density, spin, and pairing fluctuations of an attractive two-dimensional Fermi gas
Get PDFEarly Biological Response to Poly(ε-Caprolactone)/Alumina-Toughened Zirconia Composites Obtained by 3D Printing for Peri-Implant Application
Get PDFUnveiling field-coupled nanocomputing: Leaning molecules to shape readable bits
Get PDFMolecular field-coupled nanocomputing (molFCN) encodes information in the molecule charge distribution and elaborates it through electrostatic coupling. Despite the advantageous sub-nanometric size and low-power dissipation, only a few attempts have been made to validate the technology experimentally. One of the obstacles is the difficulty in measuring molecule charges to validate information encoding or integrate molFCN with complementary-metal-oxide-semiconductor (CMOS). In this work, we propose a paradigm preserving the advantages of molFCN, which exploits the position of waiving molecules to augment the information encoding. We validate the paradigm, named bend-boosted molFCN, with density functional theory using 6-(ferrocenyl)hexanethiol cations. We demonstrate that the encoded information can be electrically read by constituting a molecular junction. The paradigm is compatible with the charge-based molFCN, thus acting as a readout system. The obtained results favor the experimental assessment of the molFCN principle through scanning probe microscopy techniques and the design of molFCN-CMOS heterogeneous circuits
Unperturbed Electric Field and Operator Current Towards Ground in HV Substations: a linear relationship between two measurements
No full textAs a part of the monitoring of the electric field (E-field) generated in HV substations, a proportionality was observed between the unperturbed E-field and the electric current flowing towards ground from the body of an operator equipped with insulating footwear, measured by an ammeter, in different substation locations. This proportionality cannot be assumed a priori, as the human body capacitive coupling with the HV and surround conductors in the complex substation layout can strongly vary, depending on the measurement point. In the paper, the validity of the proposed indirect approach is validated and quantified, considering an operator moving inside an HV substation. The rationale is discussed by a specific FEM analysis including an anthropomorphic body and confirmed through experimental validation measurement. The linear dependence between the unperturbed E-field and the current flowing from the operator to ground can help speed up and simplify the human exposure assessment to the E-field through indirect, but still sufficiently accurate measurements
Simplified modeling of implanted medical devices with metallic filamentary closed loops exposed to low or medium frequency magnetic fields
Get PDFBackground and objectives: Electric currents are induced in implanted medical devices with metallic fila-mentary closed loops (e.g., fixation grids, stents) when exposed to time varying magnetic fields, as those generated during certain diagnostic and therapeutic biomedical treatments. A simplified methodology to efficiently compute these currents, to estimate the altered electromagnetic field distribution in the bio-logical tissues and to assess the consequent biological effects is proposed for low or medium frequency fields.Methods: The proposed methodology is based on decoupling the handling of the filamentary wire and the anatomical body. To do this, a circuital solution is adopted to study the metallic filamentary implant and this solution is inserted in the electromagnetic field solution involving the biological tissues. The Joule losses computed in the implant are then used as a forcing term for the thermal problem defined by the bioheat Pennes' equation. The methodology is validated against a model problem, where a reference solution is available.Results: The proposed simplified methodology is proved to be in good agreement with solutions provided by alternative approaches. In particular, errors in the amplitude of the currents induced in the wires re-sult to be always lower than 3%. After the validation, the methodology is applied to check the interactions between the magnetic field generated by different biomedical devices and a skull grid, which represents a complex filamentary wire implant.Conclusions: The proposed simplified methodology, suitable to be applied to closed loop wires in the low to intermediate frequency range, is found to be sufficiently accurate and easy to apply in realistic exposure scenarios. This modeling tool allows analyzing different types of small implants, from coronary and biliary duct stents to orthopedic grids, under a variety of exposure scenarios.(c) 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/
Correlating the properties of near-room-temperature first- and second-order magnetocaloric materials
Get PDFSeveral magnetocaloric materials have been proposed since the discovery of the Giant Magnetocaloric Effect. Although some have great potential as magnetocaloric refrigerants or working materials in thermomagnetic motors/generators, only a few have been tested experimentally or had their properties incorporated into validated mathematical models. While experiments are limited by material costs and specialized equipment to determine magnetic field-dependent properties such as specific heat capacity and magnetization, the development of correlation methods must ensure data quality and resolution over a wide range of conditions to reduce interpolations errors. Aiming to keep the number of baseline experimental data points at a minimum, we propose a fitting procedure to correlate thermomagnetic quantities (i.e., isofield specific heat capacity, magnetization and isothermal entropy change) that is accurate at intermediate (i.e., not directly measured) temperatures and applied magnetic fields. The method has been applied to different first-order materials (La(Fe,Mn,Si)
H
and MnFeP
As
) and second-order materials (Gd and Gd
Y
) with a good reproducibility of the isofield specific heat capacity, entropy–temperature diagram, adiabatic temperature change and magnetization behavior around room temperature at applied fields between 0 and 2 T