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In this work, the mesomorphic, electro-optic and dielectric properties have been discussed in the light of molecular structure-property correlations of two chiral multilactate liquid crystalline materials possessing the orthogonal paraelectric Smectic A* phase, tilted ferroelectric Smectic C* phase and the tilted antiferroelectric Smectic CA* phase, over a substantially broad temperature range. Interestingly, a reasonably rare re-entrant Smectic C* phase (SmCre*) has also been identified in one of the investigated materials. These materials differ in their linkage groups (keto or ether) and an additional chiral unit in the terminal chain. The phase transition temperatures and transition enthalpies were determined from Polarizing Optical Microscopy and Differential Scanning Calorimetry (DSC) measurements. The compounds exhibit negative dielectric anisotropy (Δε) throughout the mesomorphic range (maximum −18 and −4 in SmA* for both the compounds) and moderately high values of spontaneous polarization (∼153 nC/cm2 in SmCre* phase). The temperature dependence of the response time (τ), bulk viscosity (η) and the activation energies (Ea) throughout the mesomorphic phase have been determined from the spontaneous polarization measurements. To emphasize the structure-property correlations in more detail, dielectric spectroscopy measurement has also been performed to measure the dielectric strength, dielectric loss, frequency dependent permittivities, relaxation time and relaxation frequencies. The clear evidence of the relatively rare SmCre* phase has also been confirmed from the temperature and frequency dependence of the dielectric permittivity. These results shed important light on the emergence of these materials as a smart alternative for their application in multicomponent mixtures targeted for advanced electro-optic and photonic devices.

Recent advancements in polymer science and manufacturing technologies triggered new developments of porous materials used for mitigating heat losses, such as thermal insulating polymeric foams. The major bottleneck in the optimization of these products, however, remains the absence of analytical methods able to scrutinize their large design space reasonably quickly and cost-effectively. This manuscript targets the paucity of data for polymeric foams by illustrating, at a proof-of-principle level, that several well-established analytical methods including optical microscopy, pycnometry, dielectric spectroscopy, thermogravimetric analysis, and nuclear magnetic resonance can be exploited for an extensive, yet logistically efficient, characterization of these materials. The purpose of this study is thus introducing an experimental platform for the characterization of market foam products and for the development of new polymeric foams with pore sizes that are particularly relevant for industrial and residential thermal insulation. Since this work introduces several new methodologies, it may be used as a guide for both laboratory users and specialists in the field, who may further improve the herein proposed experimental concepts.

This study focuses on the dielectric relaxation response of insulating liquids based on mineral oil and synthetic ester in a thermal field.The research also offers the dielectric relaxation response of the magnetic nanofluid based on the investigated synthetic ester. The reason for investigating the synthetic ester-based nanofluid is that the temperature characteristics of the mineral oil-based magnetic nanofluid have already been investigated in several studies. Nanofluid based on synthetic ester is not sufficiently explored in this regard. The behavior of insulating liquids in the thermal field is divided into two parts. The first one points to the effect of temperature on the dielectric properties of the insulating liquids in the range from 293.15 K to 363.15 K. The insulating liquids show relaxation processes in the investigated frequency spectrum (1 mHz–3 kHz), which are dependent on temperature. The logarithm of the relaxation frequency decreases linearly with decreasing temperature according to Arrhenius' law. Mineral oil has the highest value of activation energy. In the second part, the results are focused on the influence of the rate of temperature increase on the dielectric parameters and moisture content of the investigated fluids. A slower increase in temperature causes an increase in polarization losses and a reduction in the distribution of relaxation times. In the case of base oils, also a reduction in activation energy. The change in the heating rate of the investigated liquids does not affect their moisture. Changes in dielectric parameters are not caused by changes in the moisture of insulating liquids, but by thermal aging.

A novel ethylene-anisylpropylene copolymer was tested as a candidate material for intrinsically self-healing electrical insulation layers. In addition to the thermal and mechanical properties, the dielectric properties were studied before and after induced mechanical and electrical damage to the specimens. The material was tested according to the standards for electrical insulating materials, which require a detailed characterization of the dielectric properties. Nonstandardized tests of self-healing were also included in the testing. The results revealed that the tested material exhibited excellent dielectric parameters and reasonable thermal and mechanical properties. The self-healing tests of the material revealed a 38 % efficiency for recovery of the mechanical properties after the first damage, and this remained almost unchanged after the second and third damage. The first initial results also indicated that the material recovered, to some extent, its electrical insulation properties even after electrical breakdown. By comparing the dielectric strength of the pristine and self-healed specimens, a promising self-healing efficiency of 63 % was determined.

Due to their tailorable morphology, silica nanoparticles (SNPs) have recently attracted widespread attention because they can be used in many emerging areas. Over the past decade, important work has been done on novel processing methodologies to prepare SNPs, which have resulted in better control over the size, shape, porosity, and notable improvements in their physio-chemical properties. Microemulsions are a simple and widely used method of preparing silica nanoparticles. The method, however, still has several flaws, such as the inability to produce the expected silica nanoparticles even under carefully designed synthesis conditions. In order to effectively use silica nanoparticles (SNs) in catalyst, adsorption, polymer filler, optical devices, bio-imaging, drug delivery, and biomedical applications, it is becoming more and more crucial to have good control over their morphology, particle size, uniformity, and dispersity. It is therefore desirable to monitor the synthesis process in real time to unravel the mechanisms behind the formation of silica nanoparticles and to promote their controllable synthesis. It has always been a hot topic in nano science to apply microemulsions using different types of surfactants to inorganic nanomaterials. Despite this, very few studies have been performed on polymer-based microemulsions based on different ionic surfactants and their relative dielectric spectroscopy (DS). This review examines various synthesis techniques for producing well-dispersed SNs and hollow silica nanoparticles (HSNs) with adjustable dimensions ranging from a few to hundreds of nanometers of various mesostructures.

ABSTRACT: The nonhomogeneity of bovine colostrum leads to strong scattering effects for electromagnetic waves, which affects the application of electromagnetic spectroscopy in detecting colostrum. This work aimed to compare the performance of near-infrared spectroscopy (NIRS) and dielectric spectroscopy (DS) in quantitatively predicting the content of mature milk as an adulterant in colostrum. The near-infrared spectra in the range of 833 to 2,500 nm and the dielectric spectra in the range of 20 to 4,500 MHz of 150 adulterated colostrum samples containing 0 to 50% mature milk were analyzed. The different proportions of mature milk in colostrum significantly changed near-infrared and dielectric spectra. The principal component analysis score plot showed that both NIRS and DS could identify the proportion of mature milk in colostrum, but the 2 methods had different characteristics. Linear partial least squares regression and nonlinear least squares support vector machine (LSSVM) models based on near-infrared and dielectric spectra were established to identify doping proportions. The results showed that DS had better identification performance with a root-mean-square error of prediction of 4.9% and a residual prediction deviation of 3.441 by successive projection algorithm LSSVM, whereas NIRS was relatively weak with a root-mean-square error of prediction of 7.3% and a residual prediction deviation of 2.301 by full-spectra LSSVM. This work provides important insights for the quantitative prediction of nonhomogeneous liquid food by DS.

Pepsin as an aspartic acid protease member and one of the three foremost proteolytic enzymes in the digestive system is essential to be detected. An electrochemically polymerized tyrosine film on carbon paste electrode (pTyr/CPE) has been synthesized by electro-polymerization donating an affordable electrochemical sensor to sense salivary pepsin as a diagnostic technique for gastroesophageal reflux disease (GRD) due to saliva collection is non-invasive and relatively comfortable. The pTyr/CPE was applied for Voltammetric sensing of pepsin and its quantification in phosphate buffer solution of pH 2.0 (PBS). Scanning electron microscopy (SEM) was conducted to learn the surface morphology. Cyclic voltammetry (CV), differential pulse voltammetry (DPVs), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) were developed to realize the electrocatalytic activity of the sensor. The pTyr/CPE proceeded as a sensitive detector to pepsin with two linear ranges from 1 to 20 & 20 to 100 ng/mL donating two limits of detection as 0.5 & 0.09 ng/mL, respectively, and high selectivity toward pepsin, as well as stability and fast response of 1.5 s. Consequently, it is guessed that the pTyr/CPE sensor could be supportive for the initial diagnosis of GRD through the detection of pepsin in saliva. Finally, we quantified the pepsin levels in saliva samples of LPR patients (n = 2), showing that the results were agreeable with those from the electrochemical sensor., Competing Interests: Declaration of competing interest no conflict of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The utilization of biomimetic membranes supported by advanced self-assembled monolayers is gaining attraction as a promising sensing tool. Biomimetic membranes offer exceptional biocompatibility and adsorption capacity upon degradation, transcending their role as mere research instruments to open new avenues in biosensing. This study focused on anchoring a sparsely tethered bilayer lipid membrane onto a self-assembled monolayer composed of a biodegradable polymer, functionalized with poly(ethylene glycol)-cholesterol moieties, for lipid membrane integration. Real-time monitoring via quartz crystal microbalance, coupled with characterization using surface-enhanced infrared absorption spectroscopy and electrochemical impedance spectroscopy, provided comprehensive insights into each manufacturing phase. The resulting lipid layer, along with transmembrane pores formed by gramicidin A, exhibited robust stability. Electrochemical impedance spectroscopy analysis confirmed membrane integrity, successful pore formation, and consistent channel density. Notably, gramicidin A demonstrated sustained functionality as an ion channel upon reconstitution, with its functionality being effectively blocked and inhibited in the presence of calcium ions. These findings mark significant strides in developing intricate biodegradable nanomaterials with promising applications in biomedicine., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Crevice corrosion in modular taper junctions of hip or knee replacements using cobalt-chrome-molybdenum (CoCrMo) alloys remains a clinical concern. Non-mechanically-driven corrosion has been less explored compared to mechanically assisted crevice corrosion. This study hypothesized that solution chemistry within crevices, inflammation, and cathodic electrode potential shifts during fretting result in low pH and generate reactive oxygen species (ROS), affecting oxide film behavior. This study investigated how resistance and capacitance of the CoCrMo oxide film (i.e., corrosion resistance) are modified in simulated in vivo crevice environments of modular taper junctions. Six solutions were evaluated (two pH levels: 1 and 7.4 and four hydrogen peroxide (H 2 O 2 ) concentrations: 0, 0.001, 0.01 and 0.1 M). R p versus voltage and Mott-Schottky plots were created from symmetry-based electrochemical impedance spectroscopy (sbEIS). At pH 1, the semiconductor transition to p-type occurs at more anodic potentials and higher flat band potentials were found. H 2 O 2 decreased the flat band potential and slope in the Mott-Schottky plot. Higher H 2 O 2 in pH 7.4 solution significantly modified the oxide film, leading to increased donor density (p = 0.0004) and a 150-fold reduction in R p in the cathodic potential range at -1 V (p = 0.0005). The most unfavorable condition (0.1 M H 2 O 2 pH 1) resulted in a 250-fold lower resistance compared to phosphate buffered saline (PBS) pH 7.4 at -1 V (p = 0.0013). This study highlights the corrosion susceptibility of CoCrMo under adverse chemical and potential conditions, identifying increased defects in the oxide film due to ROS, hydrogen ions and electrode potential. STATEMENT OF SIGNIFICANCE: Corrosion of cobalt chrome molybdenum alloy caused by direct chemical attack in the crevice region of hip replacements, such as modular taper junctions, remains a clinical concern. The junction environment contains adverse chemical compositions, including high acidity and reactive oxygen species (ROS) due to inflammatory responses against the corrosion products. We simulate inflammatory environments with different pH levels and hydrogen peroxide, representative of ROS. We employ electrochemical impedance spectroscopy and apply stepwise voltage over the range induced by tribocorrosion processes. We relate the effect of adverse chemical components on corrosion and semiconducting behavior of the oxide film using Mott-Schottky analysis. This study shows how pH and ROS concentration compromises the oxide film potentially leading to non-mechanically induced corrosion., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Jeremy L. Gilbert: Consultant for Smith and Nephew, Exactech, Naples Hospital. Research support to Clemson from The Food and Drug Administration, Bayer Inc, and Ceramtech. Owner, Syracuse Biomaterials Company, LLC. Editor-in-Chief of Journal of Biomedical Materials Research – Part B: Applied Biomaterials, J Wiley and Sons, and member of the council of Society For Biomaterials. Hwaran Lee and Mike A. Kurtz: no conflicts., (Copyright © 2024 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

Background: Fluid overload (FO) subjects patients with severe aortic stenosis (AS) to increased risk for heart failure and death after valve replacement and can be objectively quantified using bioimpedance spectroscopy (BIS)., Objectives: The authors hypothesized that in AS patients with concomitant FO, BIS-guided decongestion could improve prognosis and quality of life following transcatheter aortic valve replacement (TAVR)., Methods: This randomized, controlled trial enrolled 232 patients with severe AS scheduled for TAVR. FO was defined using a portable whole-body BIS device according to previously established cutoffs (≥1.0 L and/or ≥7%). Patients with FO (n = 111) were randomly assigned 1:1 to receive BIS-guided decongestion (n = 55) or decongestion by clinical judgment alone (n = 56) following TAVR. Patients without FO (n = 121) served as a control cohort. The primary endpoint was the composite of hospitalization for heart failure and/or all-cause death at 12 months. The secondary endpoint was the change from baseline to 12 months in the Kansas City Cardiomyopathy Questionnaire., Results: The occurrence of the primary endpoint at 12 months was significantly lower in the BIS-guided vs the non-BIS-guided decongestion group (7/55 [12.7%, all deaths] vs 18/56 [32.1%, 9 hospitalizations for heart failure and 9 deaths]; HR: 0.36; 95% CI: 0.15-0.87; absolute risk reduction = -19.4%). Outcomes in the BIS-guided decongestion group were identical to the euvolemic control group (log-rank test, P = 0.7). BIS-guided decongestion was also associated with a higher increase in the Kansas City Cardiomyopathy Questionnaire score from baseline compared to non-BIS-guided decongestion (P = 0.001)., Conclusions: In patients with severe AS and concomitant FO, quantitatively guided decongestive treatment and associated intensified management post-TAVR was associated with improved outcomes and quality of life compared to decongestion by clinical judgment alone. (Management of Fluid Overload in Patients Scheduled for Transcatheter Aortic Valve Replacement [EASE-TAVR]; NCT04556123)., Competing Interests: Funding Support and Author Disclosures This study was supported by the Austrian Society of Cardiology. Dr Dannenberg has received consulting fees from Abbott; and has received educational grants from Edwards Lifesciences. Dr Kammerlander has received speaker fees from Bayer and Boehringer Ingelheim; has received advisory board honoraria from Boehringer Ingelheim; and has received research grants from Pfizer. Dr Hengstenberg has received proctoring/speaker fees from Boston Scientific and Edwards Lifesciences; and has received institutional research grants from Abbott, Boston Scientific, Edwards Lifesciences, and Medtronic). Dr Mascherbauer has received proctor fees from Abbott and Edwards Lifesciences; has received consulting fees from Boston Scientific, Edwards Lifesciences, and Shockwave Medical; and has received educational grants from Abbott, Boston Scientific, and Edwards Lifesciences. Dr Nitsche has received speaker fees/institutional research grants from Pfizer; and has received advisory board honoraria from Prothena). All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Recently, various biosensors based on odorant-binding proteins (OBPs) were developed for the detection of odorants and pheromones. However, important data gaps exist regarding the sensitive and selective detection of aldehydes with various carbon numbers. In this work, an OBP2a-based electrochemical impedance spectroscopy (EIS) biosensor was developed by immobilizing OBP2a on a gold interdigital electrode, and was characterized by EIS and atomic force microscopy. EIS responses showed the OBP2a-based biosensor was highly sensitive to citronellal, lily aldehyde, octanal, and decanal (detection limit of 10 -11  mol/L), and was selective towards aldehydes compared with interfering odorants such as small-molecule alcohols and fatty acids (selectivity coefficients lower than 0.15). Moreover, the OBP2a-based biosensor exhibited high repeatability (relative standard deviation: 1.6%-9.1 %, n = 3 for each odorant), stability (NIC declined by 3.6 % on 6th day), and recovery (91.2%-96.6 % on three real samples). More specifically, the sensitivity of the biosensor to aldehydes was positively correlated to the molecular weight and the heterocyclic molecule structure of the odorants. These results proved the availability and the potential usage of the OBP2a-based EIS biosensor for the rapid and sensitive detection of aldehydes in aspects such as medical diagnostics, food and favor analysis, and environmental monitoring., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Intense use of microbial cells in biotechnological production requires rapid methods to monitor bacterial growth online and analyze the regulation of microbial metabolic activity. Some details of metabolic activity are examined conventionally, by changing the concentration of nutrient medium components, the concentration of metabolites, the pH, the respiratory activity, and other variables. In this case, the set of variables used may turn out insufficient and a number of critical points of the control process will remain in the shadow. The enzymatic catalysis in the bacterial cell is accompanied by a redistribution of charges inside the cell and, therefore, may lead to a change in its electrophysical characteristics. Ideally, researchers should use structurally intact and metabolically undisturbed growing cells to fully understand the enzymatic processes in microbes. Electrophysical analysis, based on the study of cells as electrophysical objects and on the measurement of their polarization characteristics, is a new approach to assessing the intravital physiological variables of cells and their heterogeneity. This article describes the theoretical principles of electrophysical analysis of bacteria and shows the possibilities of methods for examining the metabolic status of bacteria.

The insulation integrity of power and instrumentation & control cables plays a crucial role in the safe and reliable operation of nuclear power plants. Different stresses affect the insulating materials of these cables, which significantly contribute the structural changes results in the polymeric insulation. Consequently, the polymer material loses its mechanical and electrical properties causing cable insulation degradation. In this work, samples of low voltage nuclear power cable have been studied with accelerated aging tests. Combined simultaneous thermal and mechanical stresses have been applied to all samples under study. While the samples being placed in an air circulating oven at 120 °C temperature, they are coiled on a cylinder with diameter of 15 cm. The dielectric properties, capacitance and dissipation factor were measured by frequency swapping from 100 mHz to 1 kHz using a commercial dielectric response analyzer. Also, the shore D hardness was measured to investigate the changes in the mechanical property of the test specimens. Over the whole frequency range, the capacitance showed a downward trend with aging. In addition, the tanδ increased with aging for frequencies higher 10 Hz. A correlation between tanδ at 100 Hz and the insulation hardness was obtained.

The shortwave infrared spectroscopy (SWIR) is the noble method which allows to evaluate the rotational relaxation time of water (RRTW) in a sample. Because SWIR requires the reference sample of pure water, the measurement temperature is limited only at above 0 °C. In this study, we expanded this temperature limitation of SWIR by using alternative reference solutions with freezing points below 0 °C, including sugar and glycerol solutions. The results showed that some reference sample solutions are useable for evaluating RRTW in samples below 0 °C. It was found that RRTW in solution measured by newly proposed SWIR agrees with RRTW measured by dielectric spectroscopy in 10% accuracy when it is shorter than 100psec., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

This study presents a simple, fast, and sensitive label-free sensing assay for the precise enumeration of modeled pathogenic Escherichia coli K12 (E. coli K12) bacteria for the first time. The method employs the covalent binding bacteriophage technique on the surface of a reversible addition-fragmentation chain transfer (RAFT) polymer film. The Nyquist plots obtained from electrochemical impedance spectroscopy (EIS) identified the charge transfer resistance R ct was calculated from a suitable electrochemical circuit model through an evaluation of the relevant parameter after the immobilization of the bacteriophage and the binding of specific E. coli K12. The impedimetric biosensor reveals specific and reproducible detection with sensitivity in the linear working range of 10 4.2 -10 7.0 CFU/mL, a limit of detection (LOD) of 10 1.3 CFU/mL, and a short response time of 15 min. The SERS response validates the surface roughness and interaction of the SERS-tag with E. coli K12-modified electrodes. Furthermore, the covalently immobilized active phage selectivity was proved against various non-targeting bacterial strains in the presence of targeted E.coli K12 with a result of 94 % specificity and 98 % sensitivity. Therefore, the developed phage-based electrode surface can be used as a disposable, label-free impedimetric biosensor for rapid and real-time monitoring of serum samples., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Multiple sclerosis (MS) is a severe progressive autoimmune-inflammatory, demyelinating process in the central nervous system (CNS) with heterogeneous neurological symptoms appearing as a consequence of myelin break down. Myelin basic protein (MBP) makes up to 30 % of the CNS myelin [1] and it is known to be released into the cerebrospinal fluid (CSF) as a bioindicator of MS. Autoimmune encephalomyelitis (EAE) is a mice model of MS widely used for research and development of new treatments [2]. Herein, MBP specific aptamer developed for possible therapeutic purposes in mouse model [3] was applied as a bioreceptor for MBP recognition. A nanobiosensor for MBP detection and monitoring was developed by using graphene oxide (GO) nanoparticles integrated onto the screen-printed carbon electrodes (SPCE) and aptamer immobilized to create a bioactive layer on the sensor surface for MBP binding. The measurements were carried out using electrochemical impedance spectrometry (EIS). Validation studies were carried out in a biological matrix (artificial CSF) containing MBP, and MSA. The aptasensor had LOD in artificial CSF 0.01 ng/mL and showed its usability in the concentration range of 0.01 … 64 ng/mL., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In this research, we fabricated a functional conductive nanocomposite with valuable properties through a chitin (CH) and cellulose (CE) polymerization process, incorporating ZnO/(0.1, 0.2, 0.3 mol.%) CuO bioactive nanoparticles. These bioactive nanoparticles, synthesized through sol-gel and polymerization interactions, greatly enhanced the structural, dielectric, and antimicrobial characteristics of CH-CE@ZnO/CuO conductive nanocomposites. The morphological analysis revealed that these nanoparticles, with diameters ranging from 11-25 nm, formed covalent bonds with the membrane matrix, bolstering the conductive nanocomposites ' structural integrity and dielectric performance. The dielectric properties of the conductive nanocomposites were significantly enhanced by the even distribution of ZnO/CuO nanoparticles within the CH-CE composite. Additionally, antimicrobial assessments demonstrated that the CH-CE@ZnO/CuO conductive nanocomposites displayed significant antibacterial properties against the Escherichia coli and Staphylococcus aureus, showcasing their potential as active packaging materials for electronic, biosensors, and sustainable applications., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In this article, the aging behavior of nuclear-grade low voltage cables, characterized by different geometries and insulation compositions, is investigated. Cables were subjected to radio-chemical aging at different dose rates (7 Gy/h, 66 Gy/h and 400 Gy/h), in order to simulate typical aging environments inside nuclear plants. The changes of insulation properties due to aging are investigated at different scales, aiming at highlighting possible correlations between molecular-scale properties and global macroscopic material behavior (e.g., mechanical and electrical ones). Microscale material behavior is investigated by means of FTIR spectroscopy and oxidation induction time (OIT) measurements, in order to evaluate material composition changes and material resistance to oxidation, respectively. On the other side, mechanical and electrical macroscopical properties are examined through tensile stress and dielectric spectroscopy measurements. It is found that aging is deeply influenced by the effect of additives (e.g. antioxidants) inside the insulation. In particular, the presence of antioxidants delays oxidation process allowing material modifications during the early aging states to be evaluated. Dielectric spectroscopy is demonstrated to properly follow all the stages of the degradation process, confirming its appropriateness as a non-destructive condition monitoring technique for cables. Finally, the evolution with aging of the dielectric response is associated with the variations of the considered chemical and mechanical properties, allowing the derivation of correlation master curves.

The so-called Fröhlich entropy is the entropy variation of a material under the application of an electric field. This quantity can be calculated, under suitable hypotheses, from the measured real part of the static dielectric function, when the imaginary part is negligible. Although Fröhlich entropy is defined for a biased sample, a straightforward physical interpretation correlates it to the state-of-order of the considered physical system in absence of field. When Fröhlich entropy is calculated from experimental results, its trend is able to give several information about the evolution in temperature of the explored compound, especially of its phase transition features. We here provide a comprehensive review of the physical systems (dipolar liquids and nematicons, organic molecular crystals, metallic nanoparticles, inorganic disordered ferroelectrics, etc.) where this approach has been exploited with the aim of evaluating their state of order and its temperature evolution. The variety of compounds where this method has been applied demonstrates that the estimation of the Fröhlich entropy can be considered a trustworthy tool for carrying out study on the state-of-order of different classes of materials. Indeed Fröhlich entropy evaluation can be considered a fruitful and reliable investigation technique which can be exploited alongside more usual experimental approaches.

In this work, nanocomposites, based on linear low‐density polyethylene (mLLDPE), produced by metallocene catalyst, were prepared and experimentally investigated by means of thermomechanical-electrical properties and Raman spectroscopy. In particular, scanning electron microscopy (SEM), broadband dielectric spectroscopy (BDS), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), tensile and creep testing have been carried out. Several types of carbonaceous nanomaterials, including carbon nanotubes (CNTs), carbon nanofibers (CNFs) and graphene nano-fillers (GO), which have attracted significant attention for a variety of applications, were employed for the preparation of hybrid and non-hybrid nanocomposites at various loadings. It was found that the simultaneous incorporation of two different nanofiller types into a polymeric matrix, revealed better thermomechanical performance, while in particular the combination of CNTs and GO exhibited a synergistic effect between the nanofillers, supported also by BDS and Raman results. Therefore, the results of the present study offer a new perspective for the potential of mLLDPE/hybrid nanocomposites in targeted applications.

In pavement engineering, a variety of promising application technologies are found relying on a thorough understanding of the intrinsic (mainly dielectric) electrical properties of asphalt binder and concrete materials. Meanwhile, the electrical properties of asphalt materials can be further enhanced by introducing conductive additives into and it has been brought to light that, the electrically conductive asphalt is becoming an emerging subject of interest that caters to the concept of a multifunctional pavement future. In context of these, this paper presents a holistic overview of the intrinsic and enhanced electrical properties of asphalt materials, including the theoretical analyses, as well as the corresponding applications in the practice. From such a state-of-the-art review, it is worth noting that: i) an improved understanding of asphalt material has been achieved by an in-depth examination of its electrical properties; ii) the increased significance of the research domain as a whole, and the key importance of multidisciplinary collaborations for future successes, have been indicated.

We present molecular dynamics (MD) trajectories of water solutions of eight zwitterionic amino-acids (L- form) glycine (GLY), alanine (ALA), proline (PRO), threonine (THR), leucine (LEU), glutamine (GLN), histidine (HIS) and tyrosine (TYR) using various force field (OPLS-AA, Amber99ff-SB, GROMOS96 54a7, CHARMM19) and water model (SPC/E, TIP3P) combinations. Additionally, we present OPLS-AA molecular dynamics (MD) trajectories for alanine (ALA), leucine (LEU), glutamine (GLN), and tyrosine (TYR) varying the values of major force field parameters: charge on all amino acid atoms, bond length (all amino acid bonds), Lennard-Jones potential epsilon parameter and stiffness of bond angles. Our data enable to uncover sensitivity of molecular dynamics derived analysis to variation of force field and water models and force field parameters. This data set was used to understand the effect of molecular dynamics parameters on dielectric properties of amino acid solutions [1].

In this study, we aimed to use electrical impedance spectroscopy (EIS) to assess the freeze-damage level of starches from potato tubers treated with multiple freezing-thawing (FT) cycles. The results showed that the relationship between the physicochemical properties of starches and the impedance characteristics of starch paste is temperature-dependent. As the temperature rises to 70-90 °C, the impedance modules show a significant correlation with the amylose and mineral contents, gelatinization and pasting properties, short-range ordered structure, relative crystallinity, and damage level within the range of 10-1 MHz (p < 0.01). This could be because FT leads to a reduction in amylose and ion content. Compared to a high level of freeze-damaged starch (FDS), a low level of FDS has less amylopectin and more amylose. Additionally, the ions could be typically evenly distributed throughout the unbranched linear amylose structure in starch paste. At the peak gelatinization temperature, the starch paste made from a low level of FDS exhibits a weakened network structure, allowing more unbound water for ion movement and enhancing electric conduction. In conclusion, EIS can predict the damage level and properties of FDS, which can benefit the frozen starchy food industry., Competing Interests: Declaration of competing interest The authors declare no conflicts of interest., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Real-time and continuous monitoring of lactate levels in sweat has been used as an indicator of physiological information to evaluate exercise outcomes and sports performance. We developed an optimal enzyme-based biosensor to detect the concentrations of lactate in different fluids (i.e., a buffer solution and human sweat). The surface of the screen-printed carbon electrode (SPCE) was first treated with oxygen plasma and then surface-modified by lactate dehydrogenase (LDH). The optimal sensing surface of the LDH-modified SPCE was identified by Fourier transform infrared spectroscopy and electron spectroscopy for chemical analysis. After connecting the LDH-modified SPCE to a benchtop E4980A precision LCR meter, our results showed that the measured response was dependent on the lactate concentration. The recorded data exhibited a broad dynamic range of 0.1-100 mM (R 2  = 0.95) and a limit of detection of 0.1 mM, which was unachievable without the incorporation of redox species. A state-of-the-art electrochemical impedance spectroscopy (EIS) chip was developed to integrate the LDH-modified SPCE for a portable bioelectronic platform in the detection of lactate in human sweat. We believe the optimal sensing surface can improve the sensitivity of lactate sensing in a portable bioelectronic EIS platform for early diagnosis or real-time monitoring during different physical activities., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

Epoxy networks of the diglycidyl ether of bisphenol A (DGEBA) were prepared using 3,3′- and 4,4′-diaminodiphenyl sulfone isomer crosslinkers. Secondary relaxations and the glass transitions of resultant networks were probed using broadband dielectric spectroscopy (BDS). A sub-Tg γ relaxation peak for both networks shifts to higher frequencies (f) with increasing temperature in Arrhenius fashion, both processes having the same activation energy and being assigned to phenyl ring flipping in DGEBA chains. A β relaxation is assigned to local motions of dipoles that were created during crosslinking reactions. 4,4′-based networks exhibited higher Tg relative to 3,3′-based networks as per dynamic mechanical as well as BDS analyses. The Vogel–Fulcher–Tammann–Hesse equation fitted well to relaxation time vs. temperature data and comparison of Vogel temperatures suggests lower free volume per mass for the 3,3′-based network. The Kramers–Krönig transformation was used to directly calculate dc-free ɛ″ vs. f data from experimental ɛ′ vs. f data. Distribution of relaxation times (DRT) curves are bi-modal for the 3,3′-crosslinked resin suggesting large-scale microstructural heterogeneity as opposed to homogeneity for the 4,4′-based network whose DRT consists of a single peak.

This manuscript demonstrates the molecular scale cure rate dependence of di-functional epoxide based thermoset polymers cured with amines. A series of cure heating ramp rates were used to determine the influence of ramp rate on the glass transition temperature (Tg) and sub-Tg transitions and the average free volume hole size in these systems. The networks were comprised of 3,3′-diaminodiphenyl sulfone (33DDS) and diglycidyl ether of bisphenol F (DGEBF) and were cured at ramp rates ranging from 0.5 to 20 °C/min. Differential scanning calorimetry (DSC) and NIR spectroscopy were used to explore the cure ramp rate dependence of the polymer network growth, whereas broadband dielectric spectroscopy (BDS) and free volume hole size measurements were used to interrogate networks’ molecular level structural variations upon curing at variable heating ramp rates. It was found that although the Tg of the polymer matrices was similar, the NIR and DSC measurements revealed a strong correlation for how these networks grow in relation to the cure heating ramp rate. The free volume analysis and BDS results for the cured samples suggest differences in the molecular architecture of the matrix polymers due to cure heating rate dependence.

Acinetobacter baumannii (A. baumannii) is responsible for various nosocomial infections, which is known as a clinically crucial opportunistic pathogen. Therefore, rapid detection of this pathogen is critical to prevent the spread of infection and appropriate treatment. Biological detection probes, such as aptamers and synthetic receptors can be used as diagnostic layers to detect bacteria. In this work, an electrochemical aptasensor was developed for the ultrasensitive detection of A. baumannii by electrochemical impedance spectroscopy (EIS). The aptamer was immobilized on the surface of a CSPE modified with the nanocomposite Fe 3 O 4 @SiO 2 @Glyoxal (Gly) for selective and label-free detection of A. baumannii. The charge transfers resistance (R ct ) between redox couple [Fe(CN) 6 3-/4- ] and the surface of aptasensor in the Nyquist plot of EIS study was used as electroanalytical signal for detection and determination of A. baumannii. The obtained results showed that the constructed aptasensor could specifically detect A. baumannii in the concentration range from 1.0 × 10 3 -1.0 × 10 8 Colony-forming unit (CFU)/mL and with a detection limit of 150 CFU/mL (S/N = 3). In addition to its sensitivity, the biosensor exhibits high selectivity over some other pathogens. Therefore, a simple, inexpensive, rapid, label-free, selective, and sensitive electrochemical aptasensor was developed to detect A. baumannii., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Lower yields and poorer quality of biopharmaceutical products result from cell death in bioreactors. Such cell death is commonly associated with programmed cell death or apoptosis. During apoptosis, caspases are activated and cause a cascade of events that eventually lead to cell destruction. We report on an impedance spectroscopy measurement technique for the detection of total caspase-9 in buffer and complex fluids, such as cell culture media. Enhanced sensitivity is achieved by leveraging the physiochemical properties of zinc oxide and copper oxide at the electrode-solution interface. Characterisation of the biosensor surface was performed using scanning electron microscopy and indirectly using an enzyme-linked immunosorbent assay. The characteristic biomolecular interactions between the target analyte and specific capture probe of the biosensor are quantified using non-faradaic electrical impedance spectroscopy (nfEIS). The proof-of-concept biosensor demonstrated a detection limit of 0.07 U/mL (0.032 µM) in buffer. The sensor requires a low sample volume of 50 μL without the need for sample dilution facilitating rapid analysis. Using a luminescence-based assay, the presence of active caspase-9 was detected in the culture media following exposure to a pro-apoptotic agent. We envision that the caspase-9 biosensor will be useful as a cell stress screening device for apoptosis monitoring., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

Differential scanning calorimeter and broadband dielectric spectroscopy in a broad range of temperatures (150-300 K) were employed to study the d-lyxose aqueous mixture at different hydration levels. Two relaxation processes were observed in all investigated d-lyxose aqueous mixtures. A relaxation process (process-I) usually known as the primary relaxation mode which is accountable for the collective motion of d-lyxose aqueous solution, was observed above the glass transition temperature (T g ). Below T g , another process designated as process-II was found which is mainly related to the water molecule relaxation inside the d-lyxose matrix. The average relaxation times as a function of temperature and dielectric strengths of both observed relaxation processes (I & II) were analyzed for all hydration levels in d-lyxose. It was identified that the relaxation amplitude of process-II in the d-lyxose aqueous mixture was increased drastically and their activation energies were found to be approximately independent of the content of water above critical concentration, x c  = 0.28. This suggests that the dynamical process observed above x c was dominated by the presence of water clusters. In the current aqueous mixture, the critical content of water (x c ) is slightly higher as compared to previously reported aqueous mixtures, indicating a more cooperative nature of water molecules with a d-lyxose matrix. Additionally, the T g of pure water was estimated at 128 ± 5.8 K from the extrapolation of DSC T g data of the d-lyxose aqueous solution by using the well-known Gordon-Taylor equation. Our current result gives further support to the well-accepted glass transition (T g ) of pure water., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

For patients receiving organ transplants, monitoring the blood concentration of MPA can provide timely information on whether MPA has reached the effective therapeutic window to better function while reducing the incidence of rejection or adverse reactions. In this study, an electrochemical sensor for the detection of MPA was built using a nanocomposite made of CS-MWCNT and AuNPs. At the same time, the high performance liquid phase (HPLC) method for MPA was established and compared with this sensor. The surface morphology, structure, and roughness of the material on the electrode were characterized by scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FTIR), and atomic force microscopy (AFM). In addition, the electrochemical behavior of the modified electrode was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The standard curve was obtained in blank plasma, not pure buffer solution. The peak current was linearly related to the MPA concentration in the linear range of 0.001-0.1 mM with a detection limit of 0.05 μM and good anti-interference ability. Moreover, the sensor was employed with success for the determination of MPA in rat plasma with good recovery. The electrochemical sensor presented here is eco-friendly, and sensitive, and offers a great possibility for practical applicability., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

This paper presents the development of low-cost, disposable impedance-based sensors for real-time, in-line monitoring of suspension cell culture. The sensors consist of electrical discharge machining (EDM) cut aluminum electrodes and polydimethylsiloxane (PDMS) spacers, both of which are low-cost materials that can be safely disposed of. Our research demonstrates the capability of these low-cost sensors for in-line, non-invasive monitoring of suspension cell growth in cell manufacturing. We use a hybrid equivalent circuit model to extract key features/parameters from intertwined impedance signals, which are then fed to a novel physics-inspired (gray-box) model designed for α-relaxation. This model determines viable cell count (VCC), a critical quality attribute (CQA) in cell manufacturing. Predicted VCC trends are then compared with image-based cell count data to verify their accuracy., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Chuck Zhang reports financial support was provided by US Food and Drug Administration. Chuck Zhang reports financial support was provided by National Science Foundation. Chuck Zhang has patent METHODS OF DETERMINING VIABLE CELL COUNT AND IMPEDANCE-BASED BIOSENSORS FOR THE SAME pending to GEORGIA TECH RESEARCH CORPORATION., (Copyright © 2023 Elsevier B.V. All rights reserved.)