Changes In Relaxation Times Research Articles

Enantiospecific Response in Cross-Polarization Solid-State Nuclear Magnetic Resonance of Optically Active Metal Organic Frameworks.

We report herein on a NMR-based enantiospecific response for a family of optically active metal-organic frameworks. Cross-polarization of the 1H-13C couple was performed, and the intensities of the 13C nuclei NMR signals were measured to be different for the two enantiomers. In a direct-pulse experiment, which prevents cross-polarization, the intensity difference of the 13C NMR signals of the two nanostructured enantiomers vanished. This result is due to changes of the nuclear spin relaxation times due to the electron spin spatial asymmetry induced by chemical bond polarization involving a chiral center. These experiments put forward on firm ground that the chiral-induced spin selectivity effect, which induces chemical bond polarization in the J-coupling, is the mechanism responsible for the enantiospecific response. The implications of this finding for the theory of this molecular electron spin polarization effect and the development of quantum biosensing and quantum storage devices are discussed.

Insight into the glucose cosolvent induced gelation of κ-carrageenan by broadband dielectric spectroscopy

To gain insight into the mechanism of glucose cosolvent induced gelation of κ-carrageenan, the sol to gel transition of κ-carrageenan with 0–40 wt% glucose and the water molecular dynamics of these κ-carrageenan/glucose gels are studied by broadband dielectric spectroscopy. A dielectric relaxation caused by counterion fluctuation was observed in the radio frequency range. Its dielectric increment and relaxation time change with temperature and glucose concentrations, and meaning the glucose concentration does not affect the chain conformation of κ-carrageenan in sol state, but affects its chain conformation in gel state. During cooling, the conductivity decreases and an inflection point appears which shifts to higher temperature with glucose concentration. This proves the glucose induced gelation of κ-carrageenan changed. An obvious relaxation from the contributions of free water and bound water also be observed in the microwave frequency range. Its dielectric increment and relaxation time change with glucose concentrations. Based on dielectric increment, the molar concentration of bound water molecules is obtained by the aid of Cavell equation. The change of molar concentration of bound water molecules with glucose concentration supports the hypothesis about glucose cosolvent binding to κ-carrageenan gel.

Age-Related Changes in Relaxation Times, Proton Density, Myelin, and Tissue Volumes in Adult Brain Analyzed by 2-Dimensional Quantitative Synthetic Magnetic Resonance Imaging.

Quantitative synthetic magnetic resonance imaging (MRI) enables the determination of fundamental tissue properties, namely, T1 and T2 relaxation times and proton density (PD), in a single scan. Myelin estimation and brain segmentation based on these quantitative values can also be performed automatically. This study aimed to reveal the changes in tissue characteristics and volumes of the brain according to age and provide age-specific reference values obtained by quantitative synthetic MRI. This was a prospective study of healthy subjects with no history of brain diseases scanned with a multidynamic multiecho sequence for simultaneous measurement of relaxometry of T1, T2, and PD. We performed myelin estimation and brain volumetry based on these values. We performed volume-of-interest analysis on both gray matter (GM) and white matter (WM) regions for T1, T2, PD, and myelin volume fraction maps. Tissue volumes were calculated in the whole brain, producing brain parenchymal volume, GM volume, WM volume, and myelin volume. These volumes were normalized by intracranial volume to a brain parenchymal fraction, GM fraction, WM fraction, and myelin fraction (MyF). We examined the changes in the mean regional quantitative values and segmented tissue volumes according to age. We analyzed data of 114 adults (53 men and 61 women; median age, 66.5 years; range, 21-86 years). T1, T2, and PD values showed quadratic changes according to age and stayed stable or decreased until around 60 years of age and increased thereafter. Myelin volume fraction showed a reversed trend. Brain parenchymal fraction and GM fraction decreased throughout all ages. The approximation curves showed that WM fraction and MyF gradually increased until around the 40s to 50s and decreased thereafter. A significant decline in MyF was first noted in the 60s age group (Tukey test, P < 0.001). Our study showed changes according to age in tissue characteristic values and brain volumes using quantitative synthetic MRI. The reference values for age demonstrated in this study may be useful to discriminate brain disorders from healthy brains.

Observation of Energy-Dependent Carrier Scattering in Conducting Polymer Nanowire Blends for Enhanced Thermoelectric Performance.

Without sacrificing the intrinsic softness and flexibility of conducting polymers, their blends have been demonstrated to be promising to improve thermoelectric properties of conducting polymers. However, the underlying mechanism for the thermoelectric enhancement is hitherto far from clear and is worthy of being explored deeply. In this work, we report novel conducting polymer nanowire blends by physically mixing poly(3,4-ethylenedioxythiophene) (PEDOT) nanowires and polypyrrole (PPy) nanowires. By carefully tuning the energetic structure of PPy nanowires (nanofillers), the Seebeck coefficients and power factors of nanowire blends are surprisingly increased by ∼20 and ∼32% (compared to PEDOT nanowires), respectively. By means of first-principles calculations and experimental characterizations, we qualitatively confirm that the improved thermoelectric property is a consequence of a built-in energy barrier at nanowire interfaces rather than the commonly used doping/de-doping effect. Subsequently, we further employ the Kang-Snyder transport model and quantitatively demonstrate that the energy barrier involves energy-dependent carrier scattering (thus, a change of total relaxation time) at nanowire heterojunctions, which contributes to the enhanced Seebeck coefficients and power factors. Our work sheds light on the mechanism that can be adopted to design soft but high-performance thermoelectric materials with conducting polymer blends.

Early stratification of radiotherapy response by activatable inflammation magnetic resonance imaging

Tumor heterogeneity is one major reason for unpredictable therapeutic outcomes, while stratifying therapeutic responses at an early time may greatly benefit the better control of cancer. Here, we developed a hybrid nanovesicle to stratify radiotherapy response by activatable inflammation magnetic resonance imaging (aiMRI) approach. The high Pearson’s correlation coefficient R values are obtained from the correlations between the T1 relaxation time changes at 24–48 h and the ensuing adaptive immunity (R = 0.9831) at day 5 and the tumor inhibition ratios (R = 0.9308) at day 18 after different treatments, respectively. These results underscore the role of acute inflammatory oxidative response in bridging the innate and adaptive immunity in tumor radiotherapy. Furthermore, the aiMRI approach provides a non-invasive imaging strategy for early prediction of the therapeutic outcomes in cancer radiotherapy, which may contribute to the future of precision medicine in terms of prognostic stratification and therapeutic planning.

Water status and dynamics of high-moisture Mozzarella cheese as affected by frozen and refrigerated storage

High-moisture Mozzarella is one of the most exported cheeses worldwide, but affected by short shelf-life. Freezing can help to reduce waste, but its effect on quality needs to be considered. In this study, the physico-chemical changes of Mozzarella occurring during frozen storage and subsequent refrigerated storage (after thawing) were evaluated. Frozen cheeses stored at −18 °C between 1 and 4 months showed microstructural damage and different physical, textural, sensory properties. With NMR relaxometry it was possible to observe freeze-related dehydration of caseins, by measuring the changes in water relaxation times within the matrix. These modifications were confirmed by microstructural observations that showed the formation of larger serum channels in samples subjected to freezing, compared with fresh cheeses. Sensory evaluation showed skin peeling off in frozen samples. By observing the changes at various length scales it was therefore possible to identify the critical points affecting HM Mozzarella cheese quality during frozen storage.

Three-Dimensional Surface-Based Analysis of Cartilage MRI Data in Knee Osteoarthritis: Validation and Initial Clinical Application.

Traditional quantitative analysis of cartilage with MRI averages measurements (eg, thickness) across regions-of-interest (ROIs) which may reduce responsiveness. To validate and describe clinical application of a semiautomated surface-based method for analyzing cartilage relaxation times ("composition") and morphology on MRI, 3D cartilage surface mapping (3D-CaSM). Validation study in cadaveric knees and prospective observational (cohort) study in human participants. Four cadaveric knees and 14 participants aged 40-60 with mild-moderate knee osteoarthritis (OA) and 6 age-matched healthy volunteers, imaged at baseline, 1, and 6 months. 3D spoiled gradient echo, T1 rho/T2 magnetization-prepared 3D fast spin echo for mapping of T1 rho/T2 relaxation times and delayed gadolinium enhanced MRI of cartilage (dGEMRIC) using variable flip angle T1 relaxation time mapping at 3T. 3D-CaSM was validated against high-resolution peripheral quantitative computed tomography (HRpQCT) in cadaveric knees, with comparison to expert manual segmentation. The clinical study assessed test-retest repeatability and sensitivity to change over 6 months for cartilage thickness and relaxation times. Bland-Altman analysis was performed for the validation study and evaluation of test-retest repeatability. Six-month changes were assessed via calculation of the percentage of each cartilage surface affected by areas of significant change (%SC), defined using thresholds based on area and smallest detectable difference (SDD). Bias and precision (0.06 ± 0.25 mm) of 3D-CaSM against reference HRpQCT data were comparable to expert manual segmentation (-0.13 ± 0.26 mm). 3D-CaSM demonstrated significant (>SDD) 6-month changes in cartilage thickness and relaxation times in both OA participants and healthy controls. The parameter demonstrating the greatest 6-month change was T2 relaxation time (OA median %SC [IQR] = 8.8% [5.5 to 12.6]). This study demonstrates the construct validity and potential clinical utility of 3D-CaSM, which may offer advantages to conventional ROI-based methods. 2. 2. J. Magn. Reson. Imaging 2020;52:1139-1151.

‘Quasi-Tricritical’ and Glassy Dielectric Properties of a Nematic Liquid Crystalline Material

Results of dielectric studies in the nematic and isotropic liquid phases of pentylcyanobiphenyl (5CB), a model rod-like liquid crystalline material, are shown. They are based on the discussion of the evolution of dielectric constant ( ε ), its changes under the strong electric field (nonlinear dielectric effect, NDE), and finally, the primary relaxation time. It is shown that changes in ε T and NDE are entirely dominated by the impact of pretransitional fluctuations (pre-nematic and pre-isotropic, respectively) which are associated with the weakly discontinuous character of the isotropic–nematic phase transition. This influence also extends for the low-frequency, ionic species dominated, region. Notable, that the derivative-based and distortions sensitive analysis revealed the tricritical nature of the I-N transition. Although the glass transition in 5CB occurs in the deeply supercooled state at T g ≈ − 68 ° C , the dynamics (changes of the primary relaxation time) follow a previtreous pattern both in the isotropic and in the nematic phase. Finally, the discussion of the ’molecular’ vs. ‘quasi-critical’ characterizations of the isotropic and nematic phases is presented. It shows the evident prevalence of the ‘quasi-critical-picture’, which offers the consistent temperature parameterization in the total tested temperature range.

A novel MRI analysis for assessment of microvascular vasomodulation in low-perfusion skeletal muscle

Compromised microvascular reactivity underlies many conditions and injuries, but its assessment remains difficult, particularly in low perfusion tissues. In this paper, we develop a new mathematical model for the assessment of vasomodulation in low perfusion settings. A first-order model was developed to approximate changes in T1 relaxation times as a result of vasomodulation. Healthy adult rats (N = 6) were imaged on a 3-Tesla clinical MRI scanner, and vasoactive response was probed on gadofosveset using hypercapnic gases at 20% and 5% CO2 to induce vasoconstriction and vasodilation, respectively. MRI included dynamic 3D T1 mapping and T1-weighted images during gas challenge; heart rate was continuously monitored. Laser Doppler perfusion measurements were performed to corroborate MRI findings. The model was able to identify hypercapnia-mediated vasoconstriction and vasodilation through the partial derivative frac{partial {T}_{1}}{partial t}. MRI on animals revealed gradual vasoconstriction in the skeletal muscle bed in response to 20% CO2 followed by gradual vasodilation on transitioning to 5% CO2. These trends were confirmed on laser Doppler perfusion measurements. Our new mathematical model has the potential for detecting microvascular dysfunction that manifests in the early stages across multiple metabolic and ischemic pathologies.

Inhibition of normal and waxy corn starch retrogradation by sodium borohydride

After gelatinization, starch is prone to retrograde during storage, and it is a notorious challenge to inhibit starch retrogradation in papermaking, textile, and construction fields. This work aimed to develop a new method for inhibiting the retrogradation of normal corn starch (CS) and waxy corn starch (WCS) by sodium borohydride (NaBH4). Differential scanning calorimetry analysis suggested that addition of 2.0% (at dry starch basis, w/w) NaBH4 can completely inhibit WCS retrogradation. X-ray diffraction results showed that, as the NaBH4 concentration increased, the crystallinity of CS and WCS gradually decreased. After seven days of storage at 4 °C, the relative crystallinity of CS and WCS with 2.0% NaBH4 decreased by 62.22% and 100%, respectively. Low field nuclear magnetic resonance analysis showed that the incorporation of NaBH4 remarkably affected the change of relaxation time(T2). The T2 changes in the gelatinized CS and WCS with 2.0% NaBH4 were much lower than gelatinized CS and WCS without NaBH4. The addition of NaBH4 led to a reduction in the hydrogen bonding of CS and WCS, which was confirmed by Fourier transform infrared spectroscopy (FTIR). It was concluded that the addition of 2.0% NaBH4 can significantly inhibit the retrogradation of CS and WCS.

Assessment of Meniscal Healing Status by Magnetic Resonance Imaging T2 Mapping After Meniscal Repair

Background: Although the sensitivity and specificity of magnetic resonance imaging (MRI) for the diagnosis of primary meniscal tears are high, these values are lower for the assessment of healing status of repaired menisci. Purpose: To compare the accuracy of MRI T2 mapping and conventional MRI in assessing meniscal healing after repair. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: Patients who underwent meniscal repair with concurrent anterior cruciate ligament reconstruction between 2012 and 2016 and had a follow-up second-look arthroscopy were enrolled. The patients were divided into healed and incompletely/not healed groups based on the second-look arthroscopy findings. For the repaired menisci, the following were compared between the groups, (1) Stoller and Crues classification on conventional MRI with a proton density-weighted fat-saturated sequence and (2) the remaining colored meniscal tear line on T2 mapping coincident with the high signal line showing the primary tear on conventional MRI were compared. The change of T2 relaxation time (ΔT2) of the colored meniscal tear line pre- to postoperatively was compared between the groups. The mean T2 relaxation time of the whole area of the postoperative meniscus at each slice was also compared with that of control menisci to assess the whole quality of the repaired meniscus. Results: A total of 26 menisci from 24 knees were assessed (16 healed menisci, 10 incompletely/not healed menisci). According to the Crues classification on conventional MRI, 8 of 16 healed menisci and 3 of 10 incompletely/not healed menisci improved from grade 3 to 2, with there being no significant difference between the groups (P = .43). However, the colored meniscal tear line remained in only 3 of the 16 healed menisci as compared with 9 of the 10 incompletely/not healed menisci, and the presence of this colored line allowed differentiation between healed menisci and incompletely/not healed menisci (sensitivity, 81.3%; specificity, 90.0%; odds ratio, 39.0; P = .001). The mean (SD) ΔT2 was −31.1 ± 3.2 and −19.9 ± 4.4 ms in the healed and incompletely/not healed groups, respectively (P < .001). Receiver operating characteristic curve analysis showed a cutoff ΔT2 value of −22.3 ms for separation of meniscal healing (P < .001). The T2 relaxation times of the whole area of the repaired menisci were 31.7 ± 3.4 and 32.8 ± 3.8 ms in the healed and incompletely/unhealed groups, respectively (P = .69), with these values being significantly longer than the 26.9 ± 2.2 ms in the controls (P < .001). Conclusion: MRI T2 mapping allowed the differentiation of healing status after meniscal repair, with high sensitivity and specificity as compared with conventional MRI.

Combination of MRI and SEM to Assess Changes in the Chemical Properties and Permeability of Porous Media due to Barite Precipitation

The understanding of the dissolution and precipitation of minerals and its impact on the transport of fluids in porous media is essential for various subsurface applications, including shale gas production using hydraulic fracturing (“fracking”), CO2 sequestration, or geothermal energy extraction. In this work, we conducted a flow through column experiment to investigate the effect of barite precipitation following the dissolution of celestine and consequential permeability changes. These processes were assessed by a combination of 3D non-invasive magnetic resonance imaging, scanning electron microscopy, and conventional permeability measurements. The formation of barite overgrowths on the surface of celestine manifested in a reduced transverse relaxation time due to its higher magnetic susceptibility compared to the original celestine. Two empirical nuclear magnetic resonance (NMR) porosity–permeability relations could successfully predict the observed changes in permeability by the change in the transverse relaxation times and porosity. Based on the observation that the advancement of the reaction front follows the square root of time, and micro-continuum reactive transport modelling of the solid/fluid interface, it can be inferred that the mineral overgrowth is porous and allows the diffusion of solutes, thus affecting the mineral reactivity in the system. Our current investigation indicates that the porosity of the newly formed precipitate and consequently its diffusion properties depend on the supersaturation in solution that prevails during precipitation.

Magnetic softness, dynamic magnetization, and relaxation behavior of FeSiBC amorphous alloys

The variation of dynamic coercivity, core loss, permeability (μ′), and relaxation behavior with annealing temperature, frequency as well as magnetic field magnitude (Hm) for the FeSiBC amorphous alloy was systematically studied. It can be found that the dynamic coercivity (Hcd) of 6.2 A/m at 1.0 T and 50 Hz is much larger than the static coercivity (Hcs) of 1.7 A/m for the optimally annealed Fe78Si8B13C1 alloy. The increase of Hcd with the increases in frequency can be ascribed to the difficulty of domain wall motion and magnetization rotation as frequency elevates. The dynamic magnetization analysis reveals that μ′ goes up and attains a peak value as Hm increases to about 25 A/m in the low frequency range, while the μ′ does not depend on Hm in the high frequency range (f > 10 kHz). In addition, the change of magnetic relaxation time with annealing temperature and filed magnitude is discussed.

Monitoring real‐time curing of epoxies in situ using single‐sided NMR

AbstractAdhesively bonded joints using epoxy are widely used in aircraft and aerospace structures. Quality control and defect detection during epoxy curing in such applications is critical. We used single‐sided nuclear magnetic resonance (NMR) to nondestructively probe and spatially resolve the change in the characteristic NMR relaxation time (T2) of epoxies during curing on a substrate. Time‐dependent T2 values were fit to a Weibull function to model temporal changes in the NMR measurables. Our results demonstrate that the reduction in molecular mobility of various epoxy/curing agent mixtures occurs more rapidly at the interface than in the bulk. Further use of single‐sided NMR to acquire spatially resolved T2 data will provide a route for elucidatory epoxy curing studies. © 2020 Wiley Periodicals, Inc. J. Polym. Sci. 2020, 58, 616–623

Probing renal blood volume with magnetic resonance imaging

Damage to the kidney substantially reduces life expectancy. Renal tissue hypoperfusion and hypoxia are key elements in the pathophysiology of acute kidney injury and its progression to chronic kidney disease. In vivo assessment of renal haemodynamics and tissue oxygenation remains a challenge. Blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI) is sensitive to changes in the effective transversal relaxation time (T2 *) in vivo, and is non-invasive and indicative of renal tissue oxygenation. However, the renal T2 * to tissue pO2 relationship is not governed exclusively by renal blood oxygenation, but is affected by physiological confounders with alterations in renal blood volume fraction (BVf) being of particular relevance. To decipher this interference probing renal BVf is essential for the pursuit of renal MR oximetry. Superparamagnetic iron oxide nanoparticle (USPIO) preparations can be used as MRI visible blood pool markers for detailing alterations in BVf. This review promotes the opportunities of MRI-based assessment of renal BVf. Following an outline on the specifics of renal oxygenation and perfusion, changes in renal BVf upon interventions and their potential impact on renal T2 * are discussed. We also describe the basic principles of renal BVf assessment using ferumoxytol-enhanced MRI in the equilibrium concentration regimen. We demonstrate that ferumoxytol does not alter control of renal haemodynamics and oxygenation. Preclinical applications of ferumoxytol enhanced renal MRI as well as considerations for its clinical implementation for examining renal BVf changes are provided alongside practical considerations. Finally, we explore the future directions of MRI-based assessment of renal BVf.

Thermal transport properties of GaN with biaxial strain and electron-phonon coupling

Strain inevitably exists in practical GaN-based devices due to the mismatch of lattice structure and thermal expansion brought by heteroepitaxial growth and band engineering, and it significantly influences the thermal properties of GaN. In this work, thermal transport properties of GaN considering the effects from biaxial strain and electron-phonon coupling (EPC) are investigated using the first principles calculation and phonon Boltzmann transport equation. The thermal conductivity of free GaN is 263 and 257 W/mK for in-plane and cross-plane directions, respectively, which are consistent better with the experimental values in the literature than previous theoretical reports and show a nearly negligible anisotropy. Under the strain state, thermal conductivity changes remarkably. In detail, under +5% tensile strain state, average thermal conductivity at room temperature decreases by 63%, while it increases by 53% under the −5% compressive strain, which is mostly attributed to the changes in phonon relaxation time. Besides, the anisotropy of thermal conductivity changes under different strain values, which may result from the weakening effect from strain induced piezoelectric polarization. EPC is also calculated from the first principles method, and it is found to decrease the lattice thermal conductivity significantly. Specifically, the decrease shows significant dependence on the strain state, which is due to the relative changes between phonon-phonon and electron-phonon scattering rates. Under a compressive strain state, the decreases of lattice thermal conductivity are 19% and 23% for in-plane and cross-plane conditions, respectively, comparable with those under a free state. However, the decreases are small under the tensile strain state, because of the decreased electron-phonon scattering rates and increased phonon anharmonicity.

Water–fat separation in spiral magnetic resonance fingerprinting for high temporal resolution tissue relaxation time quantification in muscle

PurposeTo minimize the known biases introduced by fat in rapid T1 and T2 quantification in muscle using a single‐run magnetic resonance fingerprinting (MRF) water–fat separation sequence.MethodsThe single‐run MRF acquisition uses an alternating in‐phase/out‐of‐phase TE pattern to achieve water–fat separation based on a 2‐point DIXON method. Conjugate phase reconstruction and fat deblurring were applied to correct for B 0 inhomogeneities and chemical shift blurring. Water and fat signals were matched to the on‐resonance MRF dictionary. The method was first tested in a multicompartment phantom. To test whether the approach is capable of measuring small in vivo dynamic changes in relaxation times, experiments were run in 9 healthy volunteers; parameter values were compared with and without water–fat separation during muscle recovery after plantar flexion exercise.ResultsPhantom results show the robustness of the water–fat resolving MRF approach to undersampling. Parameter maps in volunteers show a significant (P < .01) increase in T1 (105 ± 94 ms) and decrease in T2 (14 ± 6 ms) when using water–fat‐separated MRF, suggesting improved parameter quantification by reducing the well‐known biases introduced by fat. Exercise results showed smooth T1 and T2 recovery curves.ConclusionWater–fat separation using conjugate phase reconstruction is possible within a single‐run MRF scan. This technique can be used to rapidly map relaxation times in studies requiring dynamic scanning, in which the presence of fat is problematic.

Experiment on determination of ethanol chemical shift and concentration of ethanol solution based on nuclear magnetic resonance instrument

In this designing experiment, a nuclear magnetic resonance instrument was used to study the chemical shift properties of ethanol based on the principle of magnetic shielding effect. At the same time, the nuclear magnetic resonance method was used to study the transverse relaxation time and signal strength of ethanol aqueous solution in the range of 5%to 40%. The relationship between different mass fraction of ethanol-aqueous solution and nuclear magnetic resonance signal intensity, relaxation time and solution concentration were analysed. According to the results, due to the limitation of experimental instruments, no regular changes were observed. The results show that the addition of copper sulphate can increase the ethanol content and the effect of the ethanol content on the lateral relaxation time: the ethanol content varies between 5% and 40%, and the lateral relaxation time changes from 8.42ms to 40.35ms.According to the experimental results, the empirical formulas of the concentration and lateral relaxation time of ethanol aqueous solution with fixed amount of copper sulphate were fitted. Using this relationship, the NMR measurement of the concentration of ethanol-water solution can be achieved, which provides a new method for the convenient and accurate measurement of the concentration of ethanol solution.

Quantification of magnetic nanoparticles by compensating for multiple environment changes simultaneously.

The quantification of magnetic nanoparticles is important for many applications, especially for in vivo biosensing. The magnetization harmonics used in spectroscopy of magnetic nanoparticles can be used to estimate nanoparticle number or weight. However, other effects such as temperature or relaxation time change can also influence the nanoparticle magnetization. Therefore, it is necessary to compensate for these factors when estimating the amount of magnetic nanoparticles. This paper shows through simulation that a two-dimensional scaling method can be used to improve the accuracy of nanoparticle quantification, especially when multiple effects are present which can influence the nanoparticle magnetization. Finally, an experiment was performed on a Magnetic Spectroscopy of Brownian motion (MSB) apparatus to demonstrate this method, and nanoparticle weight was determined with a mean error of 1.3 ng (1.81%).

Measurement of bioimpedance and application of Cole model to study the effect of moisturizing cream on human skin

A non-invasive method of measuring bioimpedance is presented to study the effect of moisturizing cream on human skin. A novel two-electrode system is developed to get electrical access at the area of interest on human skin. Controlled experiments are conducted for a duration of 47 days. Bioimpedance is measured by LCR meter in the frequency range of 1 Hz to 5 kHz. The measured impedance is then fitted with the Cole model and the relevant Cole parameters are extracted. Analysis of variance is performed on the Cole parameters to gain statistical relevance. It is found that one of the Cole parameters, namely the relaxation-time changes significantly due to the treatment of the skin with a moisturizing cream at more than 95% confidence level. The relaxation-time increases sharply during the treatment period and drops sharply in the post-treatment period. The effectiveness of the two types of cream is studied. The gender distinguishability during the application of a moisturizing cream is also studied. A very generic bioimpedance measurement method to assess the physiological condition of local skin is demonstrated here and the method has potential application in human skin related diseases and treatments.