Values Of Relaxation Time Research Articles

Relationship between the major parameters of warm-blooded organisms' life activity and the properties of aqueous salt solutions

<abstract> <p>We are devoted to the physical analysis of the habitat area of warm-blooded organisms – humans and many mammals. For this purpose, the establishment of equilibrium distribution of carbon dioxide in aqueous solutions of salts in contact with atmospheric air starting from some time is investigated. More precisely, the relaxation time of carbon dioxide, as a function of temperature and pH, is investigated. It is found that the pH-relaxation time <italic>τ<sub>S</sub></italic> is a very nontrivial function of temperature, pH values, and NaCl salt concentration. It was assumed that the minimum value of pH relaxation time corresponds to the optimal rate of physical processes in living matter. Using this selection principle and our experimental data, we have shown that the optimal temperature for human and mammalian life activity is close to <italic>T<sub>o</sub></italic> ≈ 37 °C. The lower and upper temperature limits for their possible activity are close to <italic>T<sub>l</sub></italic> ≈ 30 °C and <italic>T<sub>u</sub></italic> ≈ 42 °C, respectively. The optimal value of <italic>pH</italic><sub>o</sub>, determined by the same selection principle, also becomes true if supplemented by the influence of albumin and other proteins.</p> </abstract>

Нарушение закона броуновской релаксации для частиц феррита кобальта в воде

In the temperature range 0–90°C, the dynamic susceptibility of three samples of a magnetic fluid based on cobalt ferrite particles stabilized in water with a double layer of a surfactant was meas-ured. The first layer of the stabilizer was formed of auric acid molecules. The second layer consisted of a mixture of lauric acid and sodium dodecyl sulfate. The liquid samples had a small (about 10%) volume fraction of particles in order to reduce the influence of interparticle interactions and eliminate non-Newtonian rheological properties. The main parameter in which the samples differed was viscosity. It was changed by adding a small amount of polyvinyl alcohol. For all samples, in the studied temperature range the frequency dependence of the dynamic susceptibility had a quasi-Debye form with a pronounced maximum for the imaginary part. The value of the magnetization relaxation time was determined from the frequency of the maximum on the imaginary part of the dynamic susceptibility. As a result, the dependences of themagnetization relaxation time on tem-perature were obtained. To analyze the results obtained, viscosities of the samples were measured. All samples exhibited the properties of Newtonian fluids –the value of dynamic viscosity did not depend on the shear rate. The obtained results on the dynamic susceptibility and viscosity were compared by plotting relaxation times as a function of the ratio ofdynamic viscosity to absolute temperature. The resulting dependences do not fit on one universal straight line, as it is supposed to be according to the theory. The actual graph looks like a family of three different curves that di-verge as viscosity increases. In order to assess the influence of Néel relaxation on the resulting sus-ceptibility, the dynamic susceptibility of a frozen sample of the magnetic fluid was measured. The resulting susceptibility value was about 3% of the initial susceptibility of the liquid sample. Thus, despite the insignificant contribution of the Néel mechanism of magnetization relaxation to the dy-namic susceptibility, it is impossible to explain the obtained measurement results on the basis of the Brownian relaxation mechanism alone.

Penetrant shape effects on activated dynamics and selectivity in polymer melts and networks based on self-consistent cooperative hopping theory.

We generalize and apply the microscopic self-consistent cooperative hopping theory for activated penetrant dynamics in polymer melts and crosslinked networks to address the role of highly variable non-spherical molecular shape. The focus is on vastly different shaped penetrants that have identical space filling volume in order to isolate how non-spherical shape explicitly modifies dynamics over a wide range of temperature down to the kinetic glass transition temperature. The theory relates intramolecular and intermolecular structure and kinetic constraints, and reveals how different solvation packing of polymer monomers around variable shaped penetrants impact penetrant hopping. A highly shape-dependent penetrant activated relaxation, including alpha time decoupling and trajectory level cooperativity of the hopping process, is predicted in the deeply supercooled regime for relatively larger penetrants which is sensitive to whether the polymer matrix is a melt or heavily crosslinked network. In contrast, for smaller size penetrants or at high/medium temperatures the effect of isochoric penetrant shape is relatively weak. We propose an aspect ratio variable that organizes how penetrant shape influences the activated relaxation times, leading to a (near) collapse or master curve. The relative absolute values of the penetrant relaxation time (inverse hopping rate) in polymer melts versus in crosslinked networks are found to be opposite when compared at a common absolute temperature versus when they are compared at a fixed value of distance from the glass transition based on the variable Tg/T with Tg the glass transition temperature. Quantitative comparison with recent diffusion experiments on chemically complex molecular penetrants of variable shape but fixed volume in crosslinked networks reveals good agreement, and testable new predictions are made. Extension of the theoretical approach to more complex systems of high experimental interest are discussed, including applications to realize selective transport in membrane separation applications.

Utilizing a novel T1rho method to detect spinal degeneration via magnetic resonance imaging

Spinal degeneration has been linked to critical conditions such as osteoarthritis in adults aged 40+; while this condition is considered to be irreversible, we took interest in magnetic resonance imaging (MRI) for early detection of the condition. Ultimately, our purpose was to determine the effectiveness of a relatively novel T1rho method in the early detection of spinal degeneration, and we hypothesized that the early to mild progression of spinal degeneration would affect T1rho values following an MRI scan. This research utilized increasing trypsin injection dosage (0.1–0.2 mL/kg), an enzyme known to artificially simulate spinal degeneration, in the discs of a swine spinal specimen (a standard spinal cord injury model) to observe the stages of spinal degeneration at a faster pace. As it is known that increased trypsin injections would directly advance spinal degeneration, we corresponded 0.1 mL/kg trypsin-treated discs to early degeneration and 0.2 mL/kg to mild degeneration. We then scanned the treated swine spine using MRI and analyzed its quantitative T1rho (spin-lattice relaxation time) values at advancing stages of spinal degeneration. We found that T1rho values from the MRI did increase from 0.1 mL/kg of trypsin (early degeneration) to 0.2 mL/kg (mild degeneration). We were able to identify a direct correlation between T1rho values and progressing stages of spinal degeneration. Because other methods such as T1 mapping, T2 mapping, and diffusion imaging have faced limitations in diagnosing spinal degeneration, this T1rho method could prove valuable to future research and diagnosis of spinal degeneration.

Augmented thermoelectric performance of LiCaX (X = As, Sb) Half Heusler compounds via carrier concentration optimization

The present study is focussed on the detailed physical insight into the structural, thermal, and dynamical properties of 8-valence electron Half Heusler (HH) compounds LiCaX (X = As, Sb) using Density functional theory. The thermal and dynamic stabilities of the compounds are assessed via ab-initio molecular dynamic simulations and phonon dispersion calculations, respectively. The Tran-Blaha modified Becke Johnson potential is used to accurately predict the band gap of investigated compounds. It is found that they are indirect band gap semiconductors with band gaps of 2.52 eV (LiCaAs) and 2.09 eV (LiCaSb). The transport parameters are obtained for p-type and n-type doping at temperatures ranging from 300 K to 800 K by solving the Boltzmann Transport equation. The deformation potential theory is employed to calculate the temperature dependent relaxation time for both compounds. The results of the various thermoelectric parameters obtained using actual values of time-dependent relaxation time are compared with that calculated under constant relaxation time approximation. The maximum power factor is 10.95 × 1011 (4.99 × 1011) Wm−1K−2s−1 for p-type (n-type) LiCaAs and 12.53 × 1011 (5.30 × 1011) Wm−1K−2s−1 for p-type (n-type) LiCaSb at optimized carrier concentration. The obtained low lattice thermal conductivities for LiCaSb (0.66 Wm−1K−1) and LiCaAs (0.88 Wm−1K−1) are explicated it in terms of different phonon modes. The Figure of Merit at 800 K for p-type (n-type) LiCaAs is as high as 0.90 (0.73) and 0.93 (0.84) for LiCaSb at optimum carrier concentration ∼1020 cm−3 (∼1019 cm−3), which has been experimentally realized in other 8-valence electron Li-based HH compounds. The good thermoelectric performance of p-type LiCaX in comparison to n-type suggests that p-type LiCaX alloys are viable candidates for high temperature energy harvesting applications.

The capacitance/conductance and surface state intensity characteristics of the Schottky structures with ruthenium dioxide-doped organic polymer interface

The electrical behaviors of the Schottky structures with a ruthenium dioxide (RuO2) doped-polyvinyl chloride (PVC) interface were executed with a wide frequency range (from 1 kHz to 5 MHz) and voltages. The interface was obtained by dispersing RuO2 nanopowder as colloidal particles into the PVC organic polymer using the ultrasonic irradiation method. The capacitance/conductance and surface state intensity (Nss) effects of this interface on the structure have been widely discussed. Remarkable increases in capacitance (C) and conductance (G/ω) values were found, especially in the depletion zone. The series resistance of the structure (Rs) value decreases strongly with increasing frequency for + 3.5 V, down to a value of approximately 48.43 Ω at 5 MHz. Furthermore, the effect of the Rs is seen in the Cc and Gc/ω curves in the weak and strong accumulation regions. While the maximum value of the Nss is 1.42 × 1013 eV−1.cm−2 at 0.478 eV, its minimum value is 1.23 × 1013 eV−1.cm−2 at 0.540 eV. The relaxation time (τ) values change from 2.40 × 10−5 to 2.03 × 10−4 s in exponentially increasing values. It can be stated that there is an inverse relationship between the τ and distribution of the Nss values. These distributions vary depending on the applied voltage and frequency.

Diagnostic value of T2 relaxation time for hepatic iron grading in rat model of fatty and fibrotic liver.

The objective of this study was to assess the quantitative diagnostic value of T2 relaxation time for determining liver iron grades in the presence of fat and fibrosis. Sixty Sprague-Dawley (SD) male rats were randomly divided into control (10 rats) and model (50 rats) groups. The model group of coexisting iron, steatosis, and liver fibrosis was induced by intraperitoneal injection of carbon tetrachloride (CCl4) dissolved in edible vegetable oil (40% v/v). The control group received an intraperitoneal injection of 0.9% saline. All rats underwent multi-echo gradient and spin echo (M-GRASE) magnetic resonance imaging, and the T2 relaxation time of the liver was measured. The rats were killed immediately after imaging, and liver specimens were extracted for histological evaluation of steatosis, iron, and fibrosis. The relationship and differences between T2 relaxation time and liver fibrosis stage, as well as the pathological grade of hepatic steatosis, were assessed by Spearman's rank correlation coefficient, non-parametric Mann-Whitney test, and the Kruskal-Wallis test. The area under the receiver operating characteristic curve and interaction analysis were used to quantify the diagnostic performance of T2 relaxation time for detecting different degrees of liver iron grades. Six normal control rats and 34 model rats were included in this study. Fibrosis stages were F0 (n = 6), F1 (n = 6), F2 (n = 8), F3 (n = 10), and F4 (n = 10). Steatosis grades were S0 (n = 5), S1 (n = 8), S2 (n = 12), and S3 (n = 15). Hepatocyte or Kupffer cell iron grades were 0 (n = 7), 1 (n = 9), 2 (n = 12), 3 (n = 10), and 4 (n = 2). The liver fibrosis stages were positively correlated with the iron grades (P < 0.01), and the iron grades and fibrosis stages were negatively correlated with the T2 relaxation time (P < 0.01). The T2 relaxation times exhibited strongly significant differences among rats with different histologically determined iron grades (P < 0.01). Pairwise comparisons between each grade of liver iron indicated significant differences between all iron grades, except between grades 0 and 1, and between grades 1 and 2 (P > 0.05). The T2 relaxation time of the liver had an area under the receiving operating characteristic curve (AUC) of 0.965 (95% CI 0.908-0.100, P < 0.001) for distinguishing rats with a pathological grade of hepatic iron (grade ≥ 1) from those without, an AUC of 0.871 (95% CI 0.757-0.985, P < 0.001) for distinguishing rats with no iron overload (grade ≤ 1) from rats with moderate or severe iron overload (grade ≥ 2), and an AUC of 0.939 (95% CI 0.865-1.000, P < 0.001) for distinguishing rats with no to moderate iron overload (grade ≤ 2) from rats with severe iron overload (grade 3). The interaction of different pathological grades of iron, steatosis, and fibrosis has a negligible influence on the T2 relaxation time (P > 0.05). In conclusion, T2 relaxation time can assess histologically determined liver iron grades, regardless of coexisting liver steatosis or fibrosis; therefore, it is suitable for distinguishing between the presence and absence of iron deposition and it is more accurate for higher iron grading.

Hall current effect in bioconvection Oldroyd-B nanofluid flow through a porous medium with Cattaneo-Christov heat and mass flux theory

Bioconvection due to microorganisms is important area of research, considerably importance for environment and sustainable fuel cell technologies. Buongiorno nanofluid model for Cattaneo-Christov heat and mass flux theory taken into account the Oldroyd-B nanofluid and gyrotactic microorganisms in a rotating system with the effects of Hall current, and Darcy porous medium is scrutinized. The constitutive equations of the problem are transformed into nondimensional equations with the help of similarity transformations. Homotopy analysis method is used to obtain the solution. Graphs and table support the comprehesive representation of the achieved results. Radial velocity is reduced with the increasing values of relaxation time, retardation time and magnetic field parameters while heat transfer is augmented with thermal relaxation time parameter. The nanoparticles concentration is reduced with the increasing values of Schmidt number and the gyrotactic microorganisms concentration is enhanced with the increasing values of Peclet number. A nice agreement is obtained while comparing the present results numerically with the published results. The proposed mathematical model is used in biochemical engineering, meteorology, power and transportation production, optoelectronic and sensing microfabrication.

Design Principles of Responsive Relaxometric 19F Contrast Agents: Evaluation from the Point of View of Relaxation Theory and Experimental Data.

19F magnetic resonance imaging (MRI) is a promising tool in medical diagnostics. An important class of 19F MRI contrast agents is based on paramagnetic resonance enhancement. This effect allows an improvement in sensitivity by increasing the number of scans per unit of time or facilitates the development of responsive contrast agents that are based on changes in relaxation rates as a detection principle. In this work, Bloch-Redfield-Wangsness relaxation theory was used to predict the relaxation properties of existing lanthanoid and transition metal complexes of fluoroorganic ligands and to evaluate several design strategies for responsive contrast agents. Electron-nucleus dipole-dipole, Curie relaxation, and contact interactions were included in the model. Potential significance of chemical shift anisotropy-anisotropic dipolar shielding cross-correlation was discussed. The calculated and experimental results were well aligned. The presented model, along with the optimized field-dependent values of electronic relaxation times, could be used for the preliminary selection of the optimal metal ion for applications in 19F MRI. The results indicate potential advantages of other metal ions in addition to Gd3+ particularly Cu2+, Mn2+, Ni2+, Fe3+, and other lanthanoids as a part of 19F contrast agents.

Quantitative synthetic MRI for predicting locally advanced rectal cancer response to neoadjuvant chemoradiotherapy.

To investigate the value of pre-treatment quantitative synthetic MRI (SyMRI) for predicting a good response to neoadjuvant chemoradiotherapy (nCRT) in patients with locally advanced rectal cancer. This prospective study enrolled 63 patients with locally advanced rectal cancer scheduled to undergo preoperative chemoradiotherapy from January 2019 to June 2021. T1 relaxation time (T1), T2 relaxation time (T2), proton density (PD) from synthetic MRI, and apparent diffusion coefficient (ADC) from diffusion-weighted imaging (DWI) were measured. Independent-sample t-test, the Mann-Whitney U test, the Delong test, and receiver operating characteristic curve (ROC) analyses were used to predict the pathologic complete response (pCR) and T-downstaging. Among the 63 patients, 19 (30%) achieved pCR and 44 (70%) did not, and 24 (38%) achieved T-downstaging, while 44 (62%) did not. The mean T1 and T2 values were significantly lower in the pCR group compared with those in the non-pCR group and in the T-downstage group compared with those in the non-T-downstage group (all p < 0.05). There were no significant differences in the PD and ADC values between the two groups. There were no significant differences between the mean values of T1 and T2 for predicting pCR after CRT (AUC, 0.767 vs. 0.831, p = 0.37). There were no significant differences between the AUC values of T1 and T2 values for the assessment of post-CRT T-downstaging (AUC, 0.746 vs. 0.820, p = 0.506). In patients with locally advanced rectal cancer, the synthetic MRI-derived T1 relaxation time and T2 relaxation time values are promising imaging markers for predicting a good response to neoadjuvant chemoradiotherapy. • Mean T1 and T2 values were significantly lower in the pathologic complete response group and the T-downstage group. • There were no significant differences in the proton density and apparent diffusion coefficient values between the two groups.

GREEN SYNTHESIS OF CHROMIUM OXIDE NANOPARTICLES - STUDY OF ITS ANTIBACTERIAL, PHOTOCATALYTIC AND THERMODYNAMIC PROPERTIES

An endeavor has been made to report the herbal synthesis of chromium oxide (Cr2O3) nanoparticles using aqueous extract of nigella sativa seed extract as a capping agent and chromic sulphateas a precursor material. The structural, morphological and optical properties of the Cr2O3 nanoparticles were analyzed by X - ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and UV- Visible spectroscopy. The antibacterial efficacy of chromium oxide nanoparticles was tested against Staphylococcus aureus, Klebsiella pneumonia and Pseudomonas aeruginosa. The photocatalytic activity of biosynthesized Cr2O3 nanoparticles was evaluated by degrading methylene blue dye and Congo red dye under the irradiation of visible light. Apart from this, ultrasonic velocity, density and viscosity were measured for different concentrations of Cr2O3 nanofluid using ultrasonic techniques. Thermoacoustical such as adiabatic compressibility, free length, acoustic impedance, relaxation time and absorption coefficient values are computed from the measured data and the results are interpreted in terms of particle - fluid interactions.

Low-Field NMR Analyses of Gels and Starch-Stabilized Emulsions with Modified Potato Starches

Many different biopolymers are used to stabilize emulsions, of which starch is of particular concern. To improve the characteristics and technical utility of native starch, various types of changes can be made. This article is a report describing the molecular dynamics of water by the low-field nuclear magnetic resonance (LF NMR) of chemically (E 1412 and E 1420) and physically modified starch (LU 1432) gels and the effect of their use on the stability of oil/water emulsions obtained using bovine and porcine fats. The analysis of changes in spin–spin and spin–lattice relaxation times over time showed that the presence of the type of starch modification significantly affects the values of T1 and T2 relaxation times, as well as the correlation times. Research on time-related changes in water binding in oil-in-water emulsions showed that potato starch modified by chemical methods can be used as an emulsifier. Compared to physically modified starch, chemically modified starches have a much better water-binding capacity.

Textural and rheological properties of mulberry leather (pestil) produced with whole grain flours

This research aimed to determine the effects of different levels (6, 9%) of starch, wheat flour, wheat bran and whole grain flours (oat, barley, rye and wheat) on the textural and rheological properties of the mulberry leather (pestil). The highest hardness, consistency, cohesiveness and viscosity index values were determined in the mixture sample (an intermediate product in the pestil production) which containing starch, while the lowest values were determined in the samples containing wheat bran. Mixture samples containing both 6% and 9% wheat bran had generally the lowest elastic (G′) and viscous (G″) modulus values, while starch containing herle samples showed significantly higher modulus values compared to other flours. Changes in the rheological properties of the mixture samples were generally reflected in the pestil samples similarly. In general, hardness, cohesiveness and chewiness from Texture Profil Analyses (TPA) parameters of pestil samples increased with the increase of the amount of added starch, wheat bran and whole grain flours while adhesiveness decreased. With the increase in the flour level included in the formulation, the relaxation time value increased in the pestil samples containing starch and oat flour. While the breaking force values of all samples increased with the increase in the flour level added to the pestil formulations the extensibility values a general decrease occurred. In conclusion, because the flours used in the production of pestil have significant and different effects on the textural properties, while producing pestil with high fiber content using whole grain flours, it is possible to provide the desired textural properties by adjusting the addition level.

Thermally radiated micro-polar fluid with space-dependent heat source: Modified Cattaneo-Christov heat flux theory

The principle aim is to investigate the micro-inertia for vertex viscosity effects that were utilized about design to act on heat energy. Heat transfer was imposed out that unsteady distributed stagnation point flow by micro-polar fluid. That define the energy equation, Cattaneo-Christov heat flux figure was used for formal Fourier's law. Effects on exponential space-dependent heat source and linear thermal radiation were more comprise on the interpreted model. Numerical technique finite element method was occupied about the results to ordinary differential equations that were acquired against governing partial differential equations below the convenient equal transformations. This flow reach toward the departure domain displayed the absorbed flow aspect and opposite flow aspect susceptible on that physical parameters elaborate into the analysis. In view of acquired results, we observed that thermal profile downturn about extra sizably higher values of relaxation time, during increase into increasing radiation factor. An increase in vertex viscosity increases angular motion. Moreover, space-dependent heat digestion is extra applicable about cooling process. That more, the acceptance of current results was entire as growing analogy into actual circulated work.

Evaluation of the differentiation of benign and malignant breast lesions using synthetic relaxometry and the Kaiser score.

ObjectiveTo investigate whether there is added value of quantitative parameters from synthetic magnetic resonance imaging (SyMRI) as a complement to the Kaiser score (KS) to differentiate benign and malignant breast lesions.Materials and methodsIn this single-institution study, 122 patients who underwent breast MRI from March 2020 to May 2021 were retrospectively analyzed. SyMRI and dynamic contrast-enhanced MRI were performed using a 3.0-T system. Two experienced radiologists independently assigned the KS and measured the quantitative values of T1 relaxation time (T1), T2 relaxation time (T2), and proton density (PD) from SyMRI. Pathology was regarded as the gold standard. The diagnostic values were compared using the appropriate statistical tests.ResultsThere were 122 lesions (86 malignant and 36 benign) in 122 women. The T1 value was identified as the only independent factor for the differentiation of malignant and benign lesions. The diagnostic accuracy of incorporating the T1 into the KS protocol (T1+KS) was 95.1% and 92.1% for all lesions (ALL) and The American College of Radiology (ACR) Breast Imaging Reporting and Data System (BI-RADS) category 4 lesions, respectively, which was significantly higher than that of either T1 (ALL: 82.8%, P = 0.0001; BI-RADS 4: 78.9%, P = 0.002) or KS (ALL: 90.2%, P = 0.031; BI-RADS 4: 84.2%, P = 0.031) alone. The sensitivity and specificity of T1+KS were also higher than those of the T1 or KS alone. The combined diagnosis could have avoided another 15.6% biopsies compared with using KS alone.ConclusionsIncorporating T1 into the KS protocol improved both the sensitivity and specificity to differentiate benign and malignant breast lesions, thus avoiding unnecessary invasive procedures.

Ex-vivo human pancreatic specimen evaluation by 7 Tesla MRI: a prospective radiological-pathological correlation study

To compare the characteristics detected by 7Tesla (7T) MR and the histological composition of ex-vivo specimens from lesions diagnosed at preoperative CT scan as Pancreatic Ductal Adenocarcinoma (PDAC). Ten pancreatic specimens were examined. The 7T imaging protocol included both morphologic and quantitative sequences; the latter was acquired by conventional methods and a novel multiparametric method, the magnetic resonance fingerprinting (MRF) sequence. Two radiologists reviewed the images to: (1) evaluate the quality of the morphological and quantitative sequences by assigning an "image consistency score" on a 4-point scale; (2) identify the lesion, recording its characteristics; (3) perform the quantitative analysis on "target lesion" and "non target tissue". Finally, the specimen was analysed by two pathologists. Seven out of 10 lesions were PDAC, 2/10 were biliary carcinomas, whereas one lesion was an ampullary adenocarcinoma. The quality of the morphological sequences was judged "excellent". The "image consistency score" for the conventional quantitative sequences and MRF were 2.8 ± 0.42 and 2.9 ± 0.57; the "overall MR examination score" was 3.5 ± 0.53. A statistical correlation was found between the relaxation time values of conventional and MRF T1-weighted sequences (p < 0.0001), as well as between conventional and MRF fat- and water-fraction maps (p < 0.05). The "target lesion" and "non target tissue" relaxation time values were statistically different according to conventional T1-, T2-weighted, and MRF T1-weighted sequences. Conventional T1-, T2-weighted sequences and MRF derived relaxometries may be useful in differentiating between tumour and non-target pancreatic tissue. Moreover, the MRF sequence can be used to obtain reliable relaxation time data.

Dielectric relaxation and thermodynamical parameters of hydrogen bonded complexes for Heptanamide and Pentanamide with halogenated phenols in benzene

In the experiment and dielectric relaxation setup at 303 K, X-band (9.34 GHz) and J-band (7.22 GHz) microwave benches were employed. In benzene, dielectric experiments were done on hydrogen-bonded complexes of Heptanamide and Pentanamide with 4-bromophenol, 4-chlorophenol, 4-iodophenol, and 4-fluorophenol. Microwave dielectric spectra for binary mixtures of alkanamides with Halogenated phenols have been determined over the frequency range of 10 MHz to 20 GHz at 303 K. Dielectric properties such as (ε׳), (ε''), (ε0) and (ε∞) have been investigated. The geometries are optimized at B3LYP with 6-311G++ basis set. Dipole moments of the binary mixtures are calculated from the dielectric data using Higasi’s method and compared with the theoretical results. The relaxation periods (τ0) for ternary liquid combinations were measured using Higasi's approach. According to the ternary data, the relaxation time is highest for 1:1 complexes. According to the system under examination, the relaxation time value increases as the concentration of solute increases. For various ternary mixes and molecular conformations of these systems, the relaxation periods (τ0) of the two bands are compared. The dielectric relaxation energy parameters of thermodynamics (ΔFε, ΔHε, ΔSε) of amides with halogenated phenols in benzene were calculated and compared to the associated viscosity parameters.

Impedance spectroscopy, electronic transport, and dielectric relaxation studies in methylene green organic semiconductor for photovoltaic application

Organic electronic technologies are widely used in our daily life. Methylene green (MG) is a promising organic dye due to many potential properties such as easy processing, high flexibility, non-toxic, high stability, etc In our study, the dielectric properties, impedance spectroscopy, and AC conductivity of bulk MG samples have been studied in temperatures up to 453 K and in frequencies up to 5 MHz. The Impedance spectroscopy studies for our investigated bulk samples showed a single semicircle in the complex impedance spectra indicating multi-relaxation behavior. The DC conductivity shows activation and indicates that MG behaves like an organic semiconductor. It was found that the AC conductivity for MG bulk samples increased rapidly with frequency increasing. The conduction mechanism of σ AC was affected by the model of barrier hopping. An analysis of the dielectric constant is performed assuming the Maxwell-Wagner-Sillar type polarization is dominant at low frequency and high temperature. The calculated values of relaxation time and activation energies are 1.45 × 10−15 s and 0.65 eV, respectively. Our research findings candidate MG bulk samples in various photovoltaic applications such as organic light-emitting diodes.

Efficacy of fetal left ventricular modified myocardial performance index in predicting adverse perinatal outcomes in intrahepatic cholestasis of pregnancy.

SUMMARYOBJECTIVE:This study aimed to evaluate the effectiveness of fetal left ventricular modified myocardial performance index in predicting adverse perinatal outcomes for intrahepatic cholestasis of pregnancy.METHODS:A cross-sectional study was conducted, including 51 women with intrahepatic cholestasis of pregnancy and 80 healthy controls. Using Doppler ultrasonography, E-wave, A-wave, isovolumetric contraction time, isovolumetric relaxation time, and ejection time were recorded and the left ventricular modified myocardial performance index was measured.RESULTS:Findings showed that the mean left ventricular modified myocardial performance index, isovolumetric contraction time, and isovolumetric relaxation time values were statistically significantly higher while the ejection time and E/A ratios were statistically significantly lower in the intrahepatic cholestasis of pregnancy group than the control group. In the intrahepatic cholestasis of pregnancy group, a statistically significant positive correlation was found between left ventricular modified myocardial performance index and adverse perinatal outcomes in the intrahepatic cholestasis of pregnancy group (r=0.478, p<0.001), while a statistically significant negative correlation was found between the E/A ratio and adverse perinatal outcomes (r=-0.701, p<0.001).CONCLUSIONS:For intrahepatic cholestasis of pregnancy cases, high fetal left ventricular modified myocardial performance index values were an indicator of ventricular dysfunction, and this correlated with negative perinatal outcomes.

Structural-Temporal Peculiarities of Dynamic Deformation of Layered Materials.

The temporal nature of static and dynamic deformation of fibre metal laminates is discussed here. The aim of the study is to verify the proposed innovate model using layered composites. The modified relaxation model is based on the earlier formulated plasticity relaxation model for homogeneous materials. The proposed relaxation model makes it possible to describe the deformation of the layered composites from elastic to irreversible deformation, finalised by the failure moment. The developed approach allows us to consider the effects of the transition from static to dynamic loading. This means that the model-calculated dynamic limiting characteristics of the metal and the strength of brittle materials will have a determining character, depending on the loading history. The verification of the model using a glass fibre reinforced aluminium composite, glass fibre reinforced titanium composite, carbon fibre reinforced aluminium composite, and Kevlar fibre reinforced aluminium composite with different thickness ratios between metal and polymer layers is given. It is shown that the theoretical deformation curves of the metal composites at the various strain rates, finalised by brittle fracture of the polymer layers or continued irreversible deformation of remaining unbroken metal layers with destroyed polymer (fibre/epoxy) layers, are predicted. Based on the same structural−temporal parameters for five (Ti/GFRP (0/90)/Ti/GFRP(90/0)/Ti) and three (Ti/GFRP(0/90/90/0)/Ti) layers glass fibre reinforced titanium composites and the polymer layers, one-stage and two-stage stress drops during the irreversible deformation of the composite under static and dynamic loading are simulated. The change of the multi-stage fracture of the composite from static to dynamic loading and the fracture characteristic times of the polymer (100 s and 15,400 s) and the metal (8.4 ms) are correlated. Continued plastic deformation of the composite after fracture of the polymer layers is related with different values of the characteristic relaxation times of the polymer (fibre/epoxy) and the metal layers.