6,657 results match your criteria dielectric constant

An affinity prediction approach for the ligand of E3 ligase Cbl-b and an insight into substrate binding pattern.

Bioorg Med Chem 2021 Apr 2;38:116130. Epub 2021 Apr 2.

State Key Laboratory of Natural Medicines, and Jiang Su Key Laboratory of Drug Design and Optimization, China Pharmaceutical University, Nanjing 210009, China; Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing 210009, China. Electronic address:

Protein-protein interactions (PPIs) are essentially fundamental to all cellular processes, so that developing small molecule inhibitors of PPIs have great significance despite representing a huge challenge. Studying PPIs with the help of peptide motifs could obtain the structural information and reference significance to reduce the difficulty in the development of small molecules. Computational methods are powerful tools to characterize peptide-protein interactions, especially molecular dynamics simulation and binding free energy calculation. Read More

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Mobile Protons Limit the Stability of Salt Bridges in the Gas Phase: Implications for the Structures of Electrosprayed Protein Ions.

J Phys Chem B 2021 Apr 13. Epub 2021 Apr 13.

Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada.

Electrosprayed protein ions can retain native-like conformations. The intramolecular contacts that stabilize these compact gas-phase structures remain poorly understood. Recent work has uncovered abundant salt bridges in electrosprayed proteins. Read More

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Understanding ball milling mechanochemical processes with DFT calculations and microkinetic modeling.

ChemSusChem 2021 Apr 12. Epub 2021 Apr 12.

Institute of Chemical Research of Catalonia: Institut Catala d'Investigacio Quimica, -, SPAIN.

Mechanochemistry is an emerging field with many potential applications in sustainable chemistry. But despite the growing interest on the field, its underlying mechanistic foundations are not fully understood yet. This work presents the application of computational tools, such as DFT calculations in continuum and microkinetic modeling, to the analysis of mechanically activated procedures. Read More

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Performance matching between the surface structure of cucumber powdery mildew in different growth stages and the properties of surfactant solution.

Pest Manag Sci 2021 Apr 9. Epub 2021 Apr 9.

College of Chemistry and Materials Science, Shandong Agricultural University, Tai'an, Shandong, 271018, People's Republic of China.

Background: Understanding the performance matching of pesticide droplets on surface of cucumber leaves modified by powdery mildew is of practical importance for the agricultural sector. Herein, the surface texture and wettability of cucumber leaves covered by powdery mildew were systematically examined using parameters such as micromorphology, physicochemical properties and liquid droplet contact angle measurements.

Results: Our results show that powdery mildew growth can be divided into four distinct stages according to the surface texture characteristics of the diseased cucumber leaves. Read More

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Bayesian unsupervised learning reveals hidden structure in concentrated electrolytes.

J Chem Phys 2021 Apr;154(13):134902

Department of Physics, University of Cambridge, CB3 0HE Cambridge, United Kingdom.

Electrolytes play an important role in a plethora of applications ranging from energy storage to biomaterials. Notwithstanding this, the structure of concentrated electrolytes remains enigmatic. Many theoretical approaches attempt to model the concentrated electrolyte by introducing the idea of ion pairs, with ions either being tightly "paired" with a counter-ion or "free" to screen charge. Read More

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Accuracy trade-off between one-electron and excitonic spectra of cuprous halides in first-principles calculations.

J Chem Phys 2021 Apr;154(13):134704

State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China.

Because of the sophisticated error cancellation in the density functional theory (DFT)-based calculations, a theoretically more accurate input would not guarantee a better output. In this work, our first-principles GW plus Bethe-Salpeter equation calculations using pseudopotentials show that cuprous halides (CuCl and CuBr) are such extreme cases for which a better one-electron band is not accompanied with a better exciton binding energy. Moreover, we find that the exchange interaction of Cu core electrons plays a crucial role in their ground-state electronic properties, especially in the energy gap and macroscopic dielectric constant. Read More

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The structural, electronic, and optical properties of hydrofluorinated germanene (GeHF): a first-principles study.

J Mol Model 2021 Apr 6;27(5):123. Epub 2021 Apr 6.

Department of Electronics Engineering, Indian Institute of Technology (Indian School of Mines), Dhanbad, 826004, India.

The structural, electronic, and optical properties of hydrofluorinated germanene have been studied with different occupancy ratios of fluorine and hydrogen. The hybridization of H-1 s and Ge-4p orbitals in hydrogenated germanene and F-2p and Ge-4p orbitals in fluorinated germanene plays a significant role in creating an energy bandgap. The binding energy and phonon calculations confirm the stability of hydrofluorinated germanene decreases with the increase of the F to H ratio. Read More

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A procedure and device for determining complex material permittivity using the free-space resonance method.

Rev Sci Instrum 2021 Mar;92(3):035104

Chengdu Enchi Microwave Technology Co., Ltd., Chengdu, China.

The essential technologies of the complex permittivity of microwave dielectric materials are systematically designed, and the complex permittivity of materials is tested nondestructively by the free-space resonance method. A testing system was built by using a mobile surveying platform, and the complex dielectric constant of the material in the X band was nondestructively tested by using the algorithm of variable physical cavity length and constant physical cavity length. Focusing on the impact of variable physical cavity length on the test results, the cavity calibration technology is proposed to reduce the influence on the complex dielectric constant test of materials. Read More

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Demystifying the Stern layer at a metal-electrolyte interface: Local dielectric constant, specific ion adsorption, and partial charge transfer.

J Chem Phys 2021 Mar;154(12):124701

Department of Chemical and Environmental Engineering, University of California, Riverside, Riverside, California 92521, USA.

Electric double layer (EDL) represents one of the most basic concepts in electrochemistry and is pertinent to diverse engineering applications ranging from electrocatalysis to energy storage. Whereas phenomenological and coarse-grained models have been long established to describe ionic distributions in the diffuse layer, a faithful prediction of the physicochemical properties of the electrode-electrolyte interface from a molecular perspective remains a daunting challenge. In this work, we investigate the charging behavior of an Ag (111) electrode in NaF aqueous solutions leveraging experimental results and theoretical calculations based on the classical density functional theory for ion distributions in the diffuse layer and on the joint density functional theory (JDFT) for the electronic structure. Read More

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Effect of Cu Ions Implantation on Structural, Electronic, Optical and Dielectric Properties of Polymethyl Methacrylate (PMMA).

Polymers (Basel) 2021 Mar 22;13(6). Epub 2021 Mar 22.

Nuclear and Radiological Control Unit, King Abdulaziz City for Science and Technology (KACST), Riyadh 11442, Saudi Arabia.

In this work, the effect of ion bombardment on the optical properties of Polymethylmethacrylate (PMMA) was studied. Polymer samples were implanted with 500 keV Cu ions with a fluence ranging from 1 × 10 to 1 × 10 ions/cm. X-ray Diffractometer (XRD) study indicated a relatively lower variation with a higher dose of ions. Read More

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Skin-Inspired Pressure Sensor with MXene/P(VDF-TrFE-CFE) as Active Layer for Wearable Electronics.

Nanomaterials (Basel) 2021 Mar 12;11(3). Epub 2021 Mar 12.

Department of Polymer Science & Engineering and Key Laboratory of High Performance Polymer Materials & Technology of MOE, School of Chemistry & Chemical Engineering, Nanjing University, Nanjing 210023, China.

Multi-functional electronic skin is of paramount significance for wearable electronics in health monitoring, medical analysis, and human-machine interfacing systems. In order to achieve the function of natural skin, mechanical sensing with high sensitivity is an important feature of electronic skin. Inspired by the spinosum structure under the skin, herein, we fabricate a new capacitive pressure sensor with two-dimensional transition-metal carbides and nitrides (MXene) and ferroelectric polymer (P(VDF-TrFE-CFE)) as an active layer and micropatterned Cr-Au deposited on polydimethylsiloxane as flexible electrodes. Read More

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Development of a Solid and Flexible Matching Medium for Microwave Medical Diagnostic Systems.

Diagnostics (Basel) 2021 Mar 19;11(3). Epub 2021 Mar 19.

Faculty of Natural and Mathematical Sciences, King's College London, Strand, London WC2R 2LS, UK.

This paper reports the development of a new composite material as a matching medium for medical microwave diagnostic systems, where maximizing the microwave energy that penetrates the interrogated tissue is critical for improving the quality of the diagnostic images. The proposed material has several advantages over what is commonly used in microwave diagnostic systems: it is semi-flexible and rigid, and it can maximize microwave energy coupling by matching the tissue's dielectric constant without introducing high loss. The developed matching medium is a mirocomposite of barium titanate filler in polydimethylsiloxane (PDMS) in different weight-based mixing ratios. Read More

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Full Ground Ultra-Wideband Wearable Textile Antenna for Breast Cancer and Wireless Body Area Network Applications.

Micromachines (Basel) 2021 Mar 19;12(3). Epub 2021 Mar 19.

Communications Sensing and Imaging Group, James Watt School of Engineering, University of Glasgow, Scotland G12 8QQ, UK.

Wireless body area network (WBAN) applications have broad utility in monitoring patient health and transmitting the data wirelessly. WBAN can greatly benefit from wearable antennas. Wearable antennas provide comfort and continuity of the monitoring of the patient. Read More

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Studies on Surfactants, Cosurfactants, and Oils for Prospective Use in Formulation of Ketorolac Tromethamine Ophthalmic Nanoemulsions.

Pharmaceutics 2021 Mar 30;13(4). Epub 2021 Mar 30.

Drug Discovery, Delivery and Patient Care (DDDPC) Theme, Department of Pharmacy, Kingston University, Kingston upon Thames, London KT1 2EE, UK.

Nanoemulsions (NE) are isotropic, dispersions of oil, water, surfactant(s) and cosurfactant(s). A range of components (11 surfactants, nine cosurfactants, and five oils) were investigated as potential excipients for preparation of ketorolac tromethamine (KT) ocular nanoemulsion. Diol cosurfactants were investigated for the effect of their carbon chain length and dielectric constant (DEC), Log , and HLB on saturation solubility of KT. Read More

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Comparison of the Dielectric Properties of Ecoflex with L,D-Poly(Lactic Acid) or Polycaprolactone in the Presence of SWCN or 5CB.

Materials (Basel) 2021 Mar 31;14(7). Epub 2021 Mar 31.

Institute of Physics, Jagiellonian University, S. Lojasiewicza 11, 30-348 Krakow, Poland.

The main goal of this paper was to study the dielectric properties of hybrid binary and ternary composites based on biodegradable polymer Ecoflex, single walled carbon nanotubes (SWCN), and liquid crystalline 4'-pentyl-4-biphenylcarbonitrile (5CB) compound. The obtained results were compared with other created analogically to Ecoflex, hybrid layers based on biodegradable polymers such as L,D-polylactide (L,D-PLA) and polycaprolactone (PCL). Frequency domain dielectric spectroscopy (FDDS) results were analyzed taking into consideration the amount of SWCN, frequency, and temperature. Read More

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Signal Amplification in an Optical and Dielectric Biosensor Employing Liquid Crystal-Photopolymer Composite as the Sensing Medium.

Biosensors (Basel) 2021 Mar 13;11(3). Epub 2021 Mar 13.

Institute of Imaging and Biomedical Photonics, College of Photonics, National Yang Ming Chiao Tung University, Guiren District, Tainan 71150, Taiwan.

An optical and dielectric biosensor based on a liquid crystal (LC)-photopolymer composite was established in this study for the detection and quantitation of bovine serum albumin (BSA). When the nematic LC E7 was doped with 4-wt.% NOA65, a photo-curable prepolymer, and photopolymerized by UV irradiation at 20 mW/cm for 300 s, the limit of detection determined by image analysis of the LC optical texture and dielectric spectroscopic measurements was 3400 and 88 pg/mL for BSA, respectively, which were lower than those detected with E7 alone (10 μg/mL BSA). Read More

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Green Natural Rubber Composites Reinforced with Black/White Rice Husk Ashes: Effects of Reinforcing Agent on Film's Mechanical and Dielectric Properties.

Polymers (Basel) 2021 Mar 13;13(6). Epub 2021 Mar 13.

Bio-Circular-Green-Economy Technology & Engineering Center, BCGeTEC, Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok 10330, Thailand.

Green natural rubber (NR) composites reinforced with black rice husk ash (BRHA)/white rice husk ash (WRHA), using alginate as a thickening and dispersing agent and crosslinking by CaCl, was developed to improve mechanical, chemical and dielectric properties of NR-based films by using a latex aqueous microdispersion process. A maximum of 100 per hundred rubbers (phr) of rice husk ashes (RHAs) could be integrated in NR matrix without phase separation. Mechanical properties of the composite films were considerably enhanced, compared to the neat NR film. Read More

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Preparation and Characterization of CCTO/PDMS Dielectric Elastomers with High Dielectric Constant and Low Dielectric Loss.

Polymers (Basel) 2021 Mar 29;13(7). Epub 2021 Mar 29.

School of Materials Science and Engineering, Harbin University of Science and Technology, No. 52 Xuefu Road, Nangang District, Harbin 150040, China.

Dielectric elastomer (DE) is a type of electric field type electroactive polymer material that can produce greater deformation under the action of an electric field and has a faster recovery speed. It has the advantages of high energy density, large strain, low quality, and commercialization, and has become the most widely concerned and researched electroactive polymer material. In this study, copper calcium titanate (CCTO) particles with a large dielectric constant were selected as the filling phase, and a silicone rubber (PDMS) with better biocompatibility and lower elastic modulus was used as the matrix to prepare CCTO/PDMS, which is a new type of dielectric elastomer material. Read More

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Case Study of Polyvinylidene Fluoride Doping by Carbon Nanotubes.

Materials (Basel) 2021 Mar 15;14(6). Epub 2021 Mar 15.

Department of Physics, Faculty of Electrical Engineering and Communication, Brno University of Technology, Technická 2848/8, 616 00 Brno, Czech Republic.

Modern material science often makes use of polyvinylidene fluoride thin films because of various properties, like a high thermal and chemical stability, or a ferroelectric, pyroelectric and piezoelectric activity. Fibers of this polymer material are, on the other hand, much less explored due to various issues presented by the fibrous form. By introducing carbon nanotubes via electrospinning, it is possible to affect the chemical and electrical properties of the resulting composite. Read More

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Facile Use of Silver Nanoparticles-Loaded Alumina/Silica in Nanofluid Formulations for Enhanced Catalytic Performance toward 4-Nitrophenol Reduction.

Int J Environ Res Public Health 2021 Mar 15;18(6). Epub 2021 Mar 15.

Department of Physics, SCSVMV Deemed University, Kanchipuram 631561, India.

The introduction of toxic chemicals into the environment can result in water pollution leading to the degradation of biodiversity as well as human health. This study presents a new approach of using metal oxides (AlO and SiO) modified with a plasmonic metal (silver, Ag) nanoparticles (NPs)-based nanofluid (NF) formulation for environmental remediation purposes. Firstly, we prepared the AlO and SiO NFs of different concentrations (0. Read More

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Microfluidic Modules Integrated with Microwave Components-Overview of Applications from the Perspective of Different Manufacturing Technologies.

Sensors (Basel) 2021 Mar 2;21(5). Epub 2021 Mar 2.

Department of Microsystems, Faculty of Microsystem Electronics and Photonics, Wrocław University of Science and Technology, 50-370 Wrocław, Poland.

The constant increase in the number of microfluidic-microwave devices can be explained by various advantages, such as relatively easy integration of various microwave circuits in the device, which contains microfluidic components. To achieve the aforementioned solutions, four trends of manufacturing appear-manufacturing based on epoxy-glass laminates, polymer materials (mostly common in use are polydimethylsiloxane (PDMS) and polymethyl 2-methylpropenoate (PMMA)), glass/silicon substrates, and Low-Temperature Cofired Ceramics (LTCCs). Additionally, the domains of applications the microwave-microfluidic devices can be divided into three main fields-dielectric heating, microwave-based detection in microfluidic devices, and the reactors for microwave-enhanced chemistry. Read More

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Effect of Buffer Layer Capacitance on the Electrical Characteristics of Ferroelectric Polymer Capacitors and Field Effect Transistors.

Materials (Basel) 2021 Mar 8;14(5). Epub 2021 Mar 8.

Department of Creative Convergence Engineering, Hanbat National University, Yuseong-gu, Daejeon 34158, Korea.

We demonstrated the effect of a buffer layer on the electrical characteristics of ferroelectric polymer capacitors and field-effect transistors. Various polymer materials with a dielectric constant between 2 and 42 were used to form buffer layers with a similar thicknesses, but with different capacitances. In order to evaluate the characteristics of the ferroelectrics with a buffer layer, the polarization-voltage characteristics of the capacitor, the transfer characteristics, and the retention characteristics of the transistors were investigated. Read More

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Effective Permittivity of a Multi-Phase System: Nanoparticle-Doped Polymer-Dispersed Liquid Crystal Films.

Molecules 2021 Mar 7;26(5). Epub 2021 Mar 7.

Department of Physics, University Politehnica of Bucharest, Splaiul Independentei 313, 060042 Bucharest, Romania.

This paper studies the effective dielectric properties of heterogeneous materials of the type particle inclusions in a host medium, using the Maxwell Garnet and the Bruggeman theory. The results of the theories are applied at polymer-dispersed liquid crystal (PDLC) films, nanoparticles (NP)-doped LCs, and developed for NP-doped PDLC films. The effective permittivity of the composite was simulated at sufficiently high frequency, where the permittivity is constant, obtaining results on its dependency on the constituents' permittivity and concentrations. Read More

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Transference Number Determination in Poor-Dissociated Low Dielectric Constant Lithium and Protonic Electrolytes.

Polymers (Basel) 2021 Mar 14;13(6). Epub 2021 Mar 14.

Oil and Gas Institute-National Research Institute, Lubicz 25a Str., 31-503 Cracow, Poland.

Whereas the major potential of the development of lithium-based cells is commonly attributed to the use of solid polymer electrolytes (SPE) to replace liquid ones, the possibilities of the improvement of the applicability of the fuel cell is often attributed to the novel electrolytic materials belonging to various structural families. In both cases, the transport properties of the electrolytes significantly affect the operational parameters of the galvanic and fuel cells incorporating them. Amongst them, the transference number (TN) of the electrochemically active species (usually cations) is, on the one hand, one of the most significant descriptors of the resulting cell operational efficiency while on the other, despite many years of investigation, it remains the worst definable and determinable material parameter. Read More

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Simultaneous Stabilization of the Solid/Cathode Electrolyte Interface in Lithium Metal Batteries by a New Weakly Solvating Electrolyte.

Small 2021 Apr 1:e2100133. Epub 2021 Apr 1.

Department of Chemistry, Kunsan National University, Gunsan, Jeonbuk, 54150, Republic of Korea.

So far, the practical application of Li metal batteries has been hindered by the undesirable formation of Li dendrites and low Coulombic efficiencies (CEs). Herein, 1,2-diethoxyethane (DEE) is proposed as a new electrolytic solvent for lithium metal batteries (LMBs), and the performances of 1.0 m LiFSI in DEE are evaluated. Read More

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