Microwave Dielectric Response of Bovine Milk as Pregnancy Detection Tool in Dairy Cows.

The most reliable methods for pregnancy diagnosis in dairy herds include rectal palpation, ultrasound examination, and evaluation of plasma progesterone concentrations. However, these methods are expensive, labor-intensive, and invasive. Thus, there is a need to develop a practical, non-invasive, cost-effective method that can be implemented on the farm to detect pregnancy. This study suggests employing microwave dielectric spectroscopy (MDS, 0.5-40 GHz) as a method to evaluate reproduction events in dairy cows. The approach involves the integration of MDS data with information on milk solids to detect pregnancy and identify early embryonic loss in dairy cows. To test the ability to predict pregnancy according to these measurements, milk samples were collected from (i) pregnant and non-pregnant randomly selected cows, (ii) weekly from selected cows (n = 12) before insemination until a positive pregnancy test, and (iii) daily from selected cows (n = 10) prior to insemination until a positive pregnancy test. The results indicated that the dielectric strength of Δε and the relaxation time, τ, exhibited reduced variability in the case of a positive pregnancy diagnosis. Using principal component analysis (PCA), a clear distinction between pregnancy and nonpregnancy status was observed, with improved differentiation upon a higher sampling frequency. Additionally, a neural network machine learning technique was employed to develop a prediction algorithm with an accuracy of 73%. These findings demonstrate that MDS can be used to detect changes in milk upon pregnancy. The developed machine learning provides a broad classification that could be further enhanced with additional data.

The effect of ionic redistributions on the microwave dielectric response of cytosol water upon glucose uptake.

The sensitivity of cytosol water's microwave dielectric (MD) response to D-glucose uptake in Red Blood Cells (RBCs) allows the detailed study of cellular mechanisms as a function of controlled exposures to glucose and other related analytes like electrolytes. However, the underlying mechanism behind the sensitivity to glucose exposure remains a topic of debate. In this research, we utilize MDS within the frequency range of 0.5-40 GHz to explore how ionic redistributions within the cell impact the microwave dielectric characteristics associated with D-glucose uptake in RBC suspensions. Specifically, we compare glucose uptake in RBCs exposed to the physiological concentration of Ca2+ vs. Ca-free conditions. We also investigate the potential involvement of Na+/K+ redistribution in glucose-mediated dielectric response by studying RBCs treated with a specific Na+/K+ pump inhibitor, ouabain. We present some insights into the MD response of cytosol water when exposed to Ca2+ in the absence of D-glucose. The findings from this study confirm that ion-induced alterations in bound/bulk water balance do not affect the MD response of cytosol water during glucose uptake.

Microwave Dielectric Relaxation of Univalent and Bivalent Electrolyte Solutions.

The microwave dielectric relaxation of aqueous solutions of univalent (KCl, NaCl, NaI) and bivalent (CaCl2, MgCl2) electrolytes at concentrations between 0.1 and 1 M at 25 °C was investigated using a vector network analyzer (0.5≤ ν ≤ 40 GHz). The spectra of these electrolyte systems are characterized by a symmetrical broadening of the main relaxation peak and were fitted using the Cole-Cole equation. In our analysis, we provide insights into the underlying physics of the relaxation events at microscopic and mesoscopic scales by using a 3D phase space trajectory that is based on the interactions of the relaxing dipole units with their surroundings and Frohlich's B function. The effect of the solutes on the H-bond network of water with increasing concentration is evident in the microwave dielectric spectra through decreasing dielectric strengths and relaxation times. It was found that the number of perturbed water molecules is higher in the case of bivalent electrolytes and appears to be proportional to the ionic radius. In our approach, the particular dependence between the broadening parameter α and the relaxation times τ reflects the rate of interactions between the elementary dipole units and their surroundings. We provide a quantitative analysis of the level of perturbation caused by the presence of ions in the hydrogen-bond network of water. It was found that the H-bonded network of water is highly perturbed in univalent systems compared to bivalent systems due to weaker bonded hydration shells. Finally, we found significant differences between the dielectric response of NaCl and NaI. The differences, originating in the counterions Cl- and I-, which are characterized by large ionic radii and consequently weaker electric fields in their vicinity, confirm that the effect of weakly hydrated ions should not be neglected in microwave dielectric spectra analysis.

The Impact of Ca2+ on Intracellular Distribution of Hemoglobin in Human Erythrocytes.

The membrane-bound hemoglobin (Hb) fraction impacts red blood cell (RBC) rheology and metabolism. Therefore, Hb-RBC membrane interactions are precisely controlled. For instance, the signaling function of membrane-bound deoxy-Hb and the structure of the docking sites in the cytosolic domain of the anion exchanger 1 (AE-1) protein are well documented; however, much less is known about the interaction of Hb variants with the erythrocyte's membrane. Here, we identified factors other than O2 availability that control Hb abundance in the membrane-bound fraction and the possible variant-specific binding selectivity of Hb to the membrane. We show that depletion of extracellular Ca2+ by chelators, or its omission from the extracellular medium, leads to membrane-bound Hb release into the cytosol. The removal of extracellular Ca2+ further triggers the redistribution of HbA0 and HbA2 variants between the membrane and the cytosol in favor of membrane-bound HbA2. Both effects are reversible and are no longer observed upon reintroduction of Ca2+ into the extracellular medium. Fluctuations of cytosolic Ca2+ also impact the pre-membrane Hb pool, resulting in the massive transfer of Hb to the cellular cytosol. We hypothesize that AE-1 is the specific membrane target and discuss the physiological outcomes and possible clinical implications of the Ca2+ regulation of the intracellular Hb distribution.

NextGEM: Next-Generation Integrated Sensing and Analytical System for Monitoring and Assessing Radiofrequency Electromagnetic Field Exposure and Health.

The evolution of emerging technologies that use Radio Frequency Electromagnetic Field (RF-EMF) has increased the interest of the scientific community and society regarding the possible adverse effects on human health and the environment. This article provides NextGEM's vision to assure safety for EU citizens when employing existing and future EMF-based telecommunication technologies. This is accomplished by generating relevant knowledge that ascertains appropriate prevention and control/actuation actions regarding RF-EMF exposure in residential, public, and occupational settings. Fulfilling this vision, NextGEM commits to the need for a healthy living and working environment under safe RF-EMF exposure conditions that can be trusted by people and be in line with the regulations and laws developed by public authorities. NextGEM provides a framework for generating health-relevant scientific knowledge and data on new scenarios of exposure to RF-EMF in multiple frequency bands and developing and validating tools for evidence-based risk assessment. Finally, NextGEM's Innovation and Knowledge Hub (NIKH) will offer a standardized way for European regulatory authorities and the scientific community to store and assess project outcomes and provide access to findable, accessible, interoperable, and reusable (FAIR) data.

The Nature of the Low-Temperature Crossover of Water in Hard Confinement.

The dynamics of water confined in mesoporous MIP (2-3 nm pores in size) with silica gel (secondary silica; further, the abbreviation SG will be used) and MAP (10-35 nm pores in size) without SG borosilicate glasses have been studied by broadband dielectric spectroscopy (BDS), nuclear magnetic resonance (NMR), and differential scanning calorimetry (DSC). MIP samples contain secondary silica inside the pores and provide a confinement size of about 2-3 nm, whereas MAP samples are free of secondary silica and provide a confinement size of about 10-35 nm. It is shown by BDS and NMR techniques that water exhibits a dynamic crossover of around 180 K when it is confined in MIP samples. By contrast, water confined in larger pores (MAP) does not exhibit any changes in its relaxation behavior. It is also shown that the crossover temperature depends on the hydration level (the higher the hydration level, the lower the crossover temperature). Below the crossover temperature, we find that water reorientation is isotropic (NMR) and that the temperature-dependent dielectric relaxation strength (BDS) follows the tendency expected for a solid-like material. In contrast, water reorientation is related to long-range diffusion above the crossover temperature, and the dielectric relaxation strength follows the tendency expected for a liquid-like material. Furthermore, the calorimetric results are compatible with crossing a glass transition near 180 K. Finally, the results are discussed within the Gibbs-Thomson model. In this framework, the crossover could be related to ice crystals melting.

The dielectric response of hydrated water as a structural signature of nanoconfined lichen melanins.

Lichens are unique symbiotic organisms from a mutually beneficial alliance of fungi and algae/cyanobacteria that successfully survive extreme temperatures and drought conditions. Most probably such extraordinary vitality of lichens is underlain by melanins, one of the main structural and chemical lichen components, and their mutual relationship with residual water. In this paper, we propose mechanisms, which allow lichens to store up the extra water in their structure. Melanins that are constituents of the cortical lichen layer and presumably contribute to unique water-lichen interactions are chosen for physical experiments in a wide temperature domain. Two melanin pigments extracted from different lichens are studied here - eumelanin from Lobaria pulmonaria and allomelanin from Cetraria islandica. To investigate the inner melanin structure and water-melanin interactions, FTIR and BDS techniques are applied. The BDS technique was used in a wide temperature region of 123-293 K for melanins with various hydration levels. The relaxation processes related to the confinement of supercooled water - in melanins are observed and discussed in details. At medium and high hydration levels, the relaxation process in two melanins of different chemical compositions and supramolecular structures exhibits a well-known crossover that was already observed in many types of confinements. The analysis of FTIR and BDS results helps to clarify the lichen-water interaction processes.

The inhibition of glucose uptake to erythrocytes: microwave dielectric response.

Dielectric spectroscopy has been used in the study and development of non-invasive glucose monitoring (NIGM) sensors, including the range of microwave frequencies. Dielectric relaxation of red blood cell (RBC) cytosolic water in the microwave frequency band has been shown to be sensitive to variations in the glucose concentration of RBC suspensions. It has been hypothesized that this sensitivity stems from the utilization of D-glucose by RBCs. To verify this proposition, RBCs were pretreated with inhibitors of D-glucose uptake (cytochalasin B and forskolin). Then their suspensions were exposed to different D-glucose concentrations as measured by microwave dielectric spectroscopy (MDS) in the 500 MHz-40 GHz frequency band. After incubation of RBCs with either inhibitor, the dielectric response of water in the cytoplasm, and specifically its relaxation time, demonstrated minimal sensitivity to the change of D-glucose concentration in the medium. This result allows us to conclude that the sensitivity of MDS to glucose uptake is associated with variations in the balance of bulk and bound RBC cytosolic water due to intracellular D-glucose metabolism, verifying the correctness of the initial hypothesis. These findings represent a further argument to establish the dielectric response of water as a marker of glucose variation in RBCs.

Emission from human skin in the sub THz frequency band.

Recently published Radiometric measurements of human subjects in the frequency range 480-700 GHz, demonstrate the emission of blackbody radiation from the body core, rather than the skin surface. We present a detailed electromagnetic simulation of the dermis and epidermis, taking into account the presence of the sweat duct. This complex structure can be considered as an electromagnetic bio-metamaterial, whereby the layered structure, along with the topology of the sweat duct, reveals a complex interference pattern in the skin. The model is capable of accurately representing the skin greyness factor as a function of frequency and this is confirmed by radiometry of living human skin.

Hydration of methemoglobin studied by in silico modeling and dielectric spectroscopy.

The hemoglobin concentration of 35 g/dl of human red blood cells is close to the solubility threshold. Using microwave dielectric spectroscopy, we have assessed the amount of water associated with hydration shells of methemoglobin as a function of its concentration in the presence or absence of ions. We estimated water-hemoglobin interactions to interpret the obtained data. Within the concentration range of 5-10 g/dl of methemoglobin, ions play an important role in defining the free-to-bound water ratio competing with hemoglobin to recruit water molecules for the hydration shell. At higher concentrations, hemoglobin is a major contributor to the recruitment of water to its hydration shell. Furthermore, the amount of bound water does not change as the hemoglobin concentration is increased from 15 to 30 g/dl, remaining at the level of ∼20% of the total intracellular water pool. The theoretical evaluation of the ratio of free and bound water for the hemoglobin concentration in the absence of ions corresponds with the experimental results and shows that the methemoglobin molecule binds about 1400 water molecules. These observations suggest that within the concentration range close to the physiological one, hemoglobin molecules are so close to each other that their hydration shells interact. In this case, the orientation of the hemoglobin molecules is most likely not stochastic, but rather supports partial neutralization of positive and negative charges at the protein surface. Furthermore, deformation of the red blood cell shape results in the rearrangement of these structures.

The AC conductivity of human sweat ducts as the dominant factor in the sub-THz reflection coefficient of skin.

The helical nature of human sweat ducts, combined with the morphological and dielectric properties of skin, suggests electromagnetic activity in the sub-THz frequency band. A detailed electromagnetic simulation model of the skin, with embedded sweat ducts, was created. The model includes realistic dielectric properties based on the measured water content of each layer of skin, derived from Raman Spectroscopy. The model was verified by comparing it to measurements of the reflection coefficient of the palms of 13 volunteers in the frequency band 350-410 GHz. They were subjected to a measurement protocol intended to induce mental stress, thereby also activating the sweat glands. The Galvanic Skin Response was concurrently measured. Using the simulation model the optimal ac-conductivity for each measurement was found. The range of variation for all subjects was found to be from 100 S/m to a maximum value of 6000 S/m with averages of 1000 S/m. These are one order of magnitude increase from the accepted values for water at these frequencies (~100 s/m at 100 GHz). Considering the known biochemical mechanism for inducing perspiration, we conclude that these ac-conductivity levels are probably valid, even though the real time measurements of sweat ac-conductivity levels inside the duct are inaccessible.

Prediction of the structure and refractive index profile of fused fiber-optic components: A numerical and experimental study.

We report a generic theoretical framework for accurate simulation of the temporal and spatial evolution of fused fiber-optic components, fabricated by the "heat and pull" technique. The methodology is based on the solution of quasi-3D incompressible Navier-Stokes equations formulated for immiscible two-phase flow. The two-phase interface is resolved by employing an interface tracking approach combined with the immersed boundary method. The model facilitates accurate spatiotemporal prediction of the evolution of both the external shape of the optical component and the internal dopant concentration during fabrication. Validation of the model was obtained by extensive comparison to experimental results. The model was found to be a convenient theoretical tool that may reliably facilitate the design and fabrication process of a wide spectrum of optic components.

Oxygenation state of hemoglobin defines dynamics of water molecules in its vicinity.

This study focuses on assessing the possible impact of changes in hemoglobin (Hb) oxygenation on the state of water in its hydration shell as it contributes to red blood cell deformability. Microwave Dielectric Spectroscopy (MDS) was used to monitor the changes in interactions between water molecules and Hb, the number of water molecules in the protein hydration shell, and the dynamics of pre-protein water in response to the transition of Hb from the tense (T) to the relaxed (R) state, and vice versa. Measurements were performed for Hb solutions of different concentrations (5 g/dl-30 g/dl) in phosphate-buffered saline buffer. Cole-Cole parameters of the main water relaxation peak in terms of interactions of water molecules (dipole-dipole/ionic dipole) during the oxygenation-deoxygenation cycle were used to analyze the obtained data. The water mobility-represented by α as a function of ln τ-differed dramatically between the R (oxygenated) state and the T (deoxygenated) state of Hb at physiologically relevant concentrations (30 g/dl-35 g/dl or 4.5 mM-5.5 mM). At these concentrations, oxygenated hemoglobin was characterized by substantially lower mobility of water in the hydration shell, measured as an increase in relaxation time, compared to deoxyhemoglobin. This change indicated an increase in red blood cell cytosolic viscosity when cells were oxygenated and a decrease in viscosity upon deoxygenation. Information provided by MDS on the intraerythrocytic water state of intact red blood cells reflects its interaction with all of the cytosolic components, making these measurements powerful predictors of the changes in the rheological properties of red blood cells, regardless of the cause.

Physiological Monitoring and Hearing Loss: Toward a More Integrated and Ecologically Validated Health Mapping.

With an ongoing shift from managing disease toward the inclusion of maintaining health and preventing disease, the world has seen the rise of increasingly sophisticated physiological monitoring and analytics. Innovations range from wearables, smartphone-based spot monitoring to highly complex noncontact, remote monitoring, utilizing different mechanisms. These tools empower the individual to better navigate their own health. They also generate powerful insights towards the detection of subclinical symptoms or processes via existing and novel digital biomarkers. In that context, a topic that is receiving increasing interest is the modulation of human physiology around an individual "baseline" in everyday life and the impact thereof on other sensorineural body functions such as hearing. More and more fully contextualized and truly long-term physiological data are becoming available that allows deeper insights into the response of the human body to our behavior, immediate environment and the understanding of how chronic conditions are evolving. Hearing loss often goes hand in hand with chronic conditions, such as diabetes, cognitive impairment, increased risk of fall, mental health, or cardiovascular risk factors. This inspires an interest to not only look at hearing impairment itself but to take a broader view, for example, to include contextualized vital signs. Interestingly, stress and its physiological implications have also been shown to be a relevant precursor to hearing loss and other chronic conditions. This article deduces the requirements for wearables and their ecosystems to detect relevant dynamics and connects that to the need for more ecologically valid data towards an integrated and more holistic mapping of hearing characteristics.

Dielectric spectra broadening as a signature for dipole-matrix interactions. V. Water in protein solutions.

In this paper, the fifth of our series focused on the dielectric spectrum symmetrical broadening of water, we consider the solutions of methemoglobin (MetHb) in pure water and in phosphate-buffered saline (PBS). The universal character of the Cole-Cole dielectric response, which reflects the interaction of water dipoles with solute molecules, was described in Paper I [E. Levy et al., J. Chem. Phys. 136, 114502 (2012)]. It enables the interpretation of the dielectric data of MetHb solutions in a unified manner using the previously developed 3D trajectory method driven by the protein concentration. It was shown that protein hydration is determined by the interaction of water dipoles with the charges and dipoles located on the rough surfaces of the protein macromolecules. In the case of the buffered solution, the transition from a dipole-charged to a dipole-dipole interaction with the protein concentration is observed {see Paper III [A. Puzenko et al., J. Chem. Phys. 137, 194502 (2012)]}. A new approach is proposed for evaluating the amount of hydration water molecules bounded to the macromolecule that takes into account the number of positive and negative charges on the protein's surface. In the case of the MetHb solution in PBS, the hydration of the solvent ions and their interaction with charges on the protein's surface are also taken into consideration. The difference in hydration between the two solutions of MetHb is discussed.

The dielectric spectroscopy of human red blood cells during 37-day storage: ß-dispersion parameterization.

This study exploits dielectric spectroscopy to monitor the kinetics of red blood cells (RBC) storage lesions, focusing on those processes linked to cellular membrane interface known as ß-dispersion. The dielectric response of RBC suspensions, exposed to blood-bank cold storage for 37 days, was studied using time-domain dielectric spectroscopy in the frequency range 500 kHz to 200 MHz. The measured dielectric processes are characterized by their dielectric strength (Δε) and their relaxation times (τ). Changes in the dielectric properties of the RBC suspensions, due to storage-related biophysical changes, were evaluated. For a quantitative characterization of RBC vitality, we characterized the shape of fresh and stored RBC and measured their deformability as expressed by their average elongation ratio, which was achieved under a shear stress of 3.0 Pa. During the second week of storage, an increment in the evolution of the relaxation times and in the dielectric permittivity strength of about 25% was observed. We propose that the characteristic increment of ATP, during the second and third weeks of storage, is responsible for the raise of the specific capacitance of cell membrane, which in turn explains the changes observed in the dielectric response when combined with the influence of the shape changes.

Water is a biomarker of changes in the cellular environment in live animals.

The biological processes that are associated with the physiological fitness state of a cell comprise a diverse set of molecular events. Reactive oxygen species (ROS), mitochondrial dysfunction, telomere shortening, genomic instability, epigenetic changes, protein aggregation, and down-regulation of quality control mechanisms are all hallmarks of cellular decline. Stress-related and decline-related changes can be assayed, but usually through means that are highly disruptive to living cells and tissues. Biomarkers for organismal decline and aging are urgently needed for diagnostic and drug development. Our goal in this study is to provide a proof-of-concept for a non-invasive assay of global molecular events in the cytoplasm of living animals. We show that Microwave Dielectric Spectroscopy (MDS) can be used to determine the hydration state of the intracellular environment in live C. elegans worms. MDS spectra were correlative with altered states in the cellular protein folding environment known to be associated with previously described mutations in the C. elegans lifespan and stress-response pathways.

Continuous noninvasive glucose monitoring; water as a relevant marker of glucose uptake in vivo.

With diabetes set to become the number 3 killer in the Western hemisphere and proportionally growing in other parts of the world, the subject of noninvasive monitoring of glucose dynamics in blood remains a "hot" topic, with the involvement of many groups worldwide. There is a plethora of techniques involved in this academic push, but the so-called multisensor system with an impedance-based core seems to feature increasingly strongly. However, the symmetrical structure of the glucose molecule and its shielding by the smaller dipoles of water would suggest that this option should be less enticing. Yet there is enough phenomenological evidence to suggest that impedance-based methods are truly sensitive to the biophysical effects of glucose variations in the blood. We have been trying to answer this very fundamental conundrum: "Why is impedance or dielectric spectroscopy sensitive to glucose concentration changes in the blood and why can this be done over a very broad frequency band, including microwaves?" The vistas for medical diagnostics are very enticing. There have been a significant number of papers published that look seriously at this problem. In this review, we want to summarize this body of research and the underlying mechanisms and propose a perspective toward utilizing the phenomena. It is our impression that the current world view on the dielectric response of glucose in solution, as outlined below, will support the further evolution and implementation toward practical noninvasive glucose monitoring solutions.

Dielectric response of hydrated water as a structural component of nanofibrillated cellulose (NFC) from different plant sources.

The current work illuminates the interplay between nanofibrillated cellulose (NFC) films and hydrated water. The NFC films from three sources of technological importance, i.e. cotton, wood and flax, are compared. It is shown that cellulose materials present slight variations in supramolecular structure depending on the plant origin. The structural differences determine both quantity and state of the water adsorbed by cellulose. Dielectric spectroscopy was employed to study the state of hydrated water as a probe of both the overall and specific marks of NFCs' structure. The measurements, carried out in the wide frequency (10-2Hz -106Hz) and temperature (123 K-293 K) ranges, revealed the formation of non-interactive water clusters at low water content. At high water content, additional states of water were identified: Water in saturated glass-forming solution and bulk. These water states were shown to be determined by the NFC's structure and morphology.