Constant Values Research Articles

Interaction of the Polymeric Layer Derived from 3-(4-Trifluoromethyl)-phenyl)-thiophene with Synthetic Stimulants on the Phase Boundary

Modification of an electrode surface with a selective layer leads to amplification of the electrochemical signal. A film derived from electrochemically oxidized 3-(4-trifluoromethyl)-phenyl)-thiophene deposited on a graphite electrode (ThPhCF3/G) was used to estimate the affinity for synthetic stimulants (2-aminoindane, buphedrone, naphyrone) using a combination of square wave voltammetry and electrochemical impedance spectroscopy. The modified surface was characterized using Raman spectroscopy, which confirmed that the presence of the –PhCF3 group is important for the recognition of synthetic stimulants. The determined values of the adsorption constants (Kads) showed the significance of charge–transfer and/or hydrogen bond interactions between—PhCF3 groups in the polymeric film and the analyte of interest: buphedrone (9.79 × 105) < naphyrone (1.57 × 106) < 2-AI (1.87 × 106). Compared to electrodes modified with nanomaterial, PThPhCF3/G-electrodes showed the highest sensitivity in concentration range of 1–11 μmol L−1 at neutral pH and a possibility of detection of 0.43–0.56 μg mL−1 (sr = 0.05–0.12). The analytical performance of ThPhCF3/G promises good perspectives for the detection of synthetic stimulants in forensic samples without prior pretreatment.

Composition of the Water Dimer and the Heterodimers of Water with N2 and O2 in Earth's Atmosphere.

The mole fractions χ and number concentrations n of the water dimer and the heterodimers H2O-N2 and H2O-O2 in Earth's atmosphere are reported up to 20 km. The water dimer data is obtained from published values of the equilibrium constant based on the water equation of state. The mixed equilibrium constants for the heterodimers are obtained from the respective second virial coefficients using an approach introduced by Stogryn and Hirschfelder that extracts the components pertaining to pairwise interactions producing bound and metastable dimers. From these calculations, χ and n for the water dimer and the (H2O)(N2) and (H2O)(O2) heterodimers at standard sea level are 1.79(6) × 10-5, 4.77(12) × 10-5 and 9.90(5) × 10-6 and 4.55(15) × 1014, 1.23(3) × 1016 and 2.56(1) × 1015, respectively. Analytical expressions are provided for these quantities for altitudes between 0-20 km and temperatures from 200-300 K. Sea level values of χ and n are given for two specific locations.

De novo design and preparation, structural details, and cytotoxic response of a new water soluble (2,2′–bipy)–(phenylalaninato)–μ–chlorido–copper(II) drug candidate against resistant cancer cells

A new water soluble (2,2′–bipyridine)–(phenylalaninato)–μ–chlorido–copper(II) complex was synthesized using ancillary ligands, l-phenylalanine, and 2,2-bipyridine as a chemotherapeutic anticancer agent. The complex was characterized by employing various spectroscopic (UV–visible, FT-IR, EPR, elemental analysis) and single crystal X-ray diffraction technique which revealed the structure of crystal as monoclinic with P21 space group. The interaction studies of the complex with therapeutic drug target, ct-DNA were caried out using various complimentary biophysical techniques, and the corroborative results of these experiments revealed that complex binds avidly through non-covalent electrostatic binding mode in the groove region of DNA. The binding propensity was quantified by calculating the intrinsic binding constant values (Kb and Ksv) which were found to be 3.1 (±0.95) × 105M−1 and 0.4 (±0.05) × 103M−1, respectively. The cleavage studies of copper(II) based drug candidate 1 with pBR322 plasmid DNA were performed in concentration dependent manner and it was demonstrated that complex was capable of conversion of supercoiled form SC (Form I) into nicked form NC (Form II) upon incubation of 3 μM concentration, implicating efficient single strand cleavage of DNA helix. The mechanistic cleavage studies were also performed in the presence various activators viz., DMSO, NaN3, SOD, and H2O2 and the strong inhibition of cleavage process was observed in presence of NaN3 and SOD that suggested an oxidative pathway (Fenton's mechanism) for the Cu(II) complex. The cytotoxicity of the complex was evaluated by SRB assay against the resistant cancer cell lines, viz., Hop-62, MCF-7, AW13516, MDA-MB-231, and SiHa. The cytotoxicity activity demonstrated good therapeutic potency against all the tested cell lines with GI50 value of <10 μM.

Modified holographic Ricci interacting dark energy models: dynamical system analysis and Bayesian comparison

We perform a dynamical system analysis and a Bayesian model selection for a new set of interacting scenarios in the framework of modified holographic Ricci dark energy (MHR-IDE) models. The dynamical analysis shows a modified radiation epoch and a late-time attractor corresponding to an accelerated phase of holographic dark energy. In the Bayesian comparison, we use a combination of background data including type Ia supernovae, cosmic chronometers, the local value of the Hubble constant, baryon acoustic oscillations, and cosmic microwave background data. We find evidence against all the MHR-IDE scenarios studied in comparison with the Λ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\varLambda $$\\end{document}CDM when the full joint analysis is considered.

Charge Transfer Kinetics in Halide Perovskites: On the Constraints of Time-Resolved Spectroscopy Measurements.

Understanding photophysical processes in lead halide perovskites is an important aspect of optimizing the performance of optoelectronic devices. The determination of exact charge carrier extraction rate constants remains elusive, as there is a large and persistent discrepancy in the reported absolute values. In this review, we concentrate on experimental procedures adopted in the literature to obtain kinetic estimates of charge transfer processes and limitations imposed by the spectroscopy technique employed. Time-resolved techniques (e.g., transient absorption-reflection and time-resolved photoluminescence spectroscopy) are commonly employed to probe charge transfer at perovskite/transport layer interfaces. The variation in sample preparation and measurement conditions can produce a wide dispersion of the measured kinetic parameters. The selected time window and the kinetic fitting model employed introduce additional uncertainty. We discuss here evaluation strategies that rely on multiexponential fitting protocols (regular or stretched) and show how the dispersion in the reported values for carrier transfer rate constants can be resolved.

Automated method for designing extractive dividing wall columns used to separate minimum azeotropic mixtures with a heavy entrainer

Despite that the extractive divided wall column (E-DWC), which is one of the best examples of process intensification, has already found an industrial application, its design remains a new area of research. None of the few studies that have been published in the literature present a method for designing an E-DWC. Therefore, the first and fully automated design method, for the separation of minimum boiling azeotropic mixtures with a heavy entrainer (class (1.0–1a)-m1) using an extractive dividing wall column, is developed in this work. The developed method is based on the values of the phase equilibrium constant along the sides of composition simplex, with the help of the composition profile properties in the infinitely sharp splits mode and difference point equations. The efficiency of this new design method was tested on the separation of two ternary azeotropic mixtures that belong to class 1.0–1a-m1. The results show that the column trajectories, along the E-DWC, obtained by the rigorous simulation are in very good agreement with those calculated by the new design method. These results prove the reliability and accuracy of the new method.

First Principles Calculations of Novel Binary Transition Metal Oxides NaCr0.5X0.5O2 (X = Y, Tc, Rh) for Na-Ion Batteries

Recently, layered transition metal oxides have demonstrated voltage windows favorable for use as cathodes in sodium-ion batteries, leading to increased specific capacity and energy density. Here, NaCr0.5Y0.5O2, NaCr0.5Tc0.5O2, and NaCr0.5Rh0.5O2 were studied by using first-principles calculations to elucidate their properties. There is a trigonal arrangement in the structure of both pure and substituted NaCrO2. Structural characteristics reveal the ferromagnetic behavior of these compounds (NaCr0.5X0.5O2; X = Y, Tc, Rh). We calculated the density of states and spin-polarized electronic band structures for the three compounds tested. NaCr0.5Y0.5O2 and NaCr0.5Rh0.5O2 exhibit diluted magnetic semiconductor (DMS) behavior, while NaCr0.5Tc0.5O2 has half-metallic (HM) behavior. The substitutional material’s ferromagnetic nature is confirmed by the negative values of the exchange constants (Nօ α and Nօ β). The fractional value of the magnetic moment also confirms the DMS nature of NaCr0.5Y0.5O2 and NaCr0.5Rh0.5O2, while the HM behavior is confirmed by the integral value of the magnetic moment for NaCr0.5Tc0.5O2. The thermoelectric characteristics were computed using the BoltzTraP code. Alectrochemical analysis of NaCr0.5Y0.5O2 showed a theoretical discharge capacity of 400 mhAg−1 and an average intercalation voltage of 4.87 V, calculated from the total energies of the optimized compounds and their de-sodianted phases. These theoretical computations demonstrate that the binary layered TM oxides studied are appropriate substances to employ in coin cell fabrication as cathodes.

NONLINEAR DYNAMICS METHODS APPLICATIONS TO PRODUCT LIFECYCLE MANAGEMENT

The research being carried out is aimed at applying nonlinear dynamics methods in product life cycle management to improve communication between processes and achieve environmental sustainability. The purpose of the article is to create a nonlinear mathematical model for analysing product lifecycle management. Chaotic nonlinear dynamical processes of product lifecycle are deterministic but have the property that even small uncertainties in initial conditions lead to exponentially growing errors in the management that limit long-term forecasts. The emergence of chaotic behaviour in processes of product lifecycle was explored, focusing on fluctuations. The study employed methods such as systems analysis, correlation analysis, nonlinear dynamics, and the Surrogate model of chaotic Lorenz waterwheel. It was identified that sharp technological innovations as the primary drivers of short-term fluctuations impacting fixed efficiency and effectiveness of product life cycle process development. The resulting nonlinear dynamic model allowed for flexible operation, transitioning between equilibrium, periodic, and chaotic states based on coefficient values for asset growth rates and time constants reflecting product life cycle process dynamics. The research results are valuable for companies seeking to reduce their environmental impact and implement circular economy principles.

Stability of asymmetric Schwarzschild–Rindler–de Sitter thin shell wormhole

The paper examines the dynamics of asymmetric thin shell wormholes that connect two distinct spacetimes using the cut and paste technique. The focus is on analyzing the linear stability of these wormholes by considering radial perturbations and utilizing the modified generalized Chaplygin gas equation of state. The specific case of an asymmetric wormhole connecting Schwarzschild–Rindler spacetime to Schwarzschild–Rindler–de Sitter space–time is analyzed using this formalism. Our investigation uncovers the existence of both stable and unstable regions, which are contingent upon the appropriate selection of various parameters within the metric spacetime and equation of state. Additionally, we determine that stability regions exist as a consequence of the square speed of sound. By increasing the value of the cosmological constant, the stability region is expanded. Furthermore, the stability regions are augmented by the influence of Rindler parameters, while the stability regions are also affected by adjustments in the equation of state parameters, leading to their enlargement.

Condensation of refractory minerals on igneous compact type A Ca‐Al‐rich inclusion from Northwest Africa 7865 CV chondrite

AbstractA melilite‐rich, compact type A Ca‐Al‐rich inclusion (CAI), KU‐N‐02, from the reduced CV3 chondrite Northwest Africa 7865, is mantled by an åkermanite‐poor layer. We carried out a combined study of petrographic observations and in situ O and Al–Mg isotopic measurements for KU‐N‐02. The core shows a typical texture of igneous compact type A CAIs. The mantle consists of spinel, åkermanite‐poor melilite, and perovskite. Individual mantle melilite crystals show reverse zoning toward the crystal grain boundary, in contrast to core melilite crystals showing normal zoning. The O isotopic compositions of the minerals in KU‐N‐02 plot along the carbonaceous chondrite anhydrous mineral line on a three O‐isotope diagram. The mantle and core spinel crystals are uniformly 16O‐rich (Δ17O ~ −23‰). The mantle melilite crystals exhibit variable O isotopic compositions ranging between Δ17O ~ −2‰ and −9‰, in contrast to the uniformly 16O‐poor (Δ17O ~ −2‰) core melilite. The mantle melilite crystals also exhibit variable δ25Mg values (δ25MgDSM‐3 ~ −2‰ to +3‰) compared with the nearly constant δ25Mg values of the core melilite (δ25MgDSM‐3 ~ +2‰). The mantle minerals are likely to have formed by condensation from the solar nebular gas after core formation. The Al–Mg mineral isochrons of the core and mantle give initial 26Al/27Al ratios of (4.66 ± 0.15) × 10−5 and (4.74 ± 0.14) × 10−5, respectively. The age difference between the core and mantle formation is estimated to be within ~0.05 Myr, implying that both melting and condensation processes in the variable O isotopically solar nebular environments occurred within a short time during single CAI formation.

Impact of Bi2O3 on the Structural, Optical, Radiation Shielding, and Dielectric Analysis of Lead Borosilicate Glasses Doped with TiO2

Objective: The principal aim of this investigation was to assess the impact of bismuth oxide on the optical properties, radiation shielding characteristics, and dielectric behavior of lead borosilicate glasses doped with titanium oxide at a low concentration. Method: We intended to utilize the conventional rapid melt quenching method to produce glasses with the following chemical composition: 25 PbO+ 15 B2O3 + 0.1 TiO2 + (59.9-x) SiO2 : x Bi2O3(0≤x≤12). Findings: XRD and SEM analyses were used to confirm the samples' non-crystalline properties, while DTA investigations were used to evaluate the samples' ability to form glass. The numerous structural elements were identified through the utilization of FT–IR and Raman analyses. The optical characteristics of glasses are determined by optical absorption studies. The findings derived from optical absorption spectral analyses revealed a progressive increase in the concentration of octahedral Ti4+ ions with the mol% Bi2O3 concentration. In order to analyse the glasses' dielectric properties, an impudence analyser was employed. The results obtained from these inquiries indicate that glasses do contain Bi2O3 at concentrations lower than 12 mol% experience a progressive increase in dielectric constant values. Further investigation is conducted into the radiation shielding properties of the glasses. Novelty: The findings indicate that the values of the glasses' optical band gap, radiation shielding ability, dielectric constant, and thermal stability are all directly correlated with their Bi2O3 concentration. Keywords: FT­IR, Raman, OBG, MAC, Activation Energy

Control system optimisation of biodiesel-based gas turbine for ship propulsion

&lt;p&gt;Reducing a gas emission of shipping transportations become a main goal of international maritime organization to achieve a clean energy. One of best scenarios to achieve this goal is to shift a fossil fuel to a renewable energy-based fuel of a ship propulsion. This paper studies an optimization of a control system of the renewable-based small gas turbine engine for the ship propulsion. Proposed control system consists of a proportional-integral with engine performance limiters to avoid an engine damage. Proportional-integral gains are tuned by a whale optimization algorithm. A gain scheduling analysis of a step response is performed to obtain a searching area of tuning parameters and values of constant gains. In this step, the gains are modeled as function of plant variables. After the searching area is obtained, the proportional-integral gains are optimized using the whale optimization algorithm while the additional gains are set as constant values. Using this scenario, stable and optimal gains have been successfully achieved. Results show that the proposed method has better performance than that of the previous methods, i.e. gain scheduling and gain scheduling optimized by the whale optimization algorithm. The proposed method has lowest fitness value and does not have an overshoot problem.&lt;/p&gt;

Finite algebras in the design of multivariate cryptography algorithms

A new approach to the design of multivariate public-key cryptalgorithms is introduced. It envisages using non-linear mappings defined as squaring and cubic operations in finite fields represented as finite algebras. The developed approach allows significant reduction of the size of public key and thereby make post-quantum algorithms of multivariate cryptography much more practical. In the developed algorithms, the secret key includes a set of values of structural constants that determine the modifications of the finite fields used and the coefficients in the set of sixth degree polynomials that make up the public key

Ударное возбуждение магнитоупругой системы периодической последовательностью сверхкоротких импульсов поля

The nonlinear magnetization precession in normal magnetized ferrite film which has magnetic, elastic and magnetoelastic properties is investigated. The excitation field is presented as a vibration on resonance frequency which is modulated by short pulses which frequency is more lower than resonance frequency. It is proposed the formation procedure of periodic succession of ultra-short pulses by the involution to even degree of modulation signal sine. It is found two different cases of excitation: first when modulate pulse duration is larger than initial signal period and second when modulate pulse duration is smaller than initial signal period. In the first case the modulated signal has the form of main frequency vibrations tandem and in the second case the modulated signal has the form of unit sign-variation pulse. It is investigated the time development of magnetic and elastic vibrations whish are firmed by excitation field. It is shown that in the first case the magnetization vibrations at first hat sharp jump to upward and after this decreases by exponent. In this case the elastic vibrations after the same jump at first increases and then decreases by exponent. The elastic vibrations behaviour is interpret as energy pump from magnetic system to elastic system. In the second case the initial jump both vibrations is absent. It is investigated the degree modulation index influence to excited vibrations. It is shown that by increasing of this index the amplitude of magnetic and elastic vibrations decreases. It is investigated the magnetization excited vibrations character by different degree of magnetoelastic connection. It is introduced the coefficient multiple of magnetoelastic constant which is equal to ratio of considered constant to value of magnetoelastic constant of yttrium iron garnet. It is shown that by increasing of multiple coefficient the magnetization vibrations period is increased. It is found the sharp increasing the period by determined value of multiple coefficient which has a threshold character. It is investigated the excitation of magnetization in large time interval when the multiple coefficient is above the threshold value. It is found the principle difference between two cases when pulse duration is large or smaller as alternating field period. It is shown that in the first case the magnetization vibrations has the character of equilibrium position precession in conditions of orientational transition. In the second case the magnetization vibrations has the form of periodic re-orientational jumps from one equilibrium position to another. It is mentioned some properties of observed phenomena and proposed some recommendations for further investigations.

Experimental Investigation of The Effects of Biodiesel/Methanol Mixtures on Diesel Fuel on Engine Performance and Emission Values in A Diesel Engine.

In internal combustion engines, operating conditions, engine design and fuel properties are closely related to efficiency. The alternative fuel used in diesel engines is expected to improve performance and emission values. Biodiesel is widely used to improve the fuel properties of alcohol and diesel. In this study, the effects of diesel, diesel-methanol, diesel-biodiesel, diesel-biodiesel-methanol mixtures are examined. Engine performance and exhaust emission tests were carried out on a three-cylinder, four-stroke diesel engine at a constant speed of 1500 rpm and five different loads: no load, 25%, 50%, 75% and 90%. Since constant speed and torque values could not be obtained in the no-load condition (T0) in the studies, the values at T0 were not used in the comparisons. As experimental data, thermal efficiency, CO, HC, CO2, NO emission values, in-cylinder pressure values and heat release rate values were examined. In experimental studies, the effects of adding different amounts of biodiesel and methanol on engine performance and emission values were compared with diesel.

Flavonoids as dual-action agents for anticancer and anti-tooth caries: a molecular docking and dynamics simulation on MMP2 inhibition

Objective: Cancer pathogenesis is linked to matrix metalloproteinase-2 (MMP2). Numerous studies have indicated an elevated expression of MMP2 in the tissue microenvironment of different cancers, including breast, oral, prostate, ovarian, colorectal, bladder, lung, and hepatocellular carcinoma. The significant role of MMP2 in the degradation of organic compounds in dentin, causing dental caries, has been indicated by accumulating evidence. This study explored the possibility of using flavonoids as natural compounds capable of inhibiting MMP2 to meet the need for new and potent MMP2 inhibitors. Methods: The AutoDock software evaluated the binding energies between selected flavonoids and the MMP2 catalytic domain and ranked the ligands based on their inhibition constant (Ki) values and Gibbs free binding energy scores. The Discovery Studio Visualizer tool demonstrated how the highest-ranked flavonoids interact with the MMP2. Molecular dynamics was conducted for the most potent MMP2 inhibitor in a 100 ns computer simulation. Results: Kaempferol 3-rutinoside-7-sophoroside demonstrated an inhibitory effect against MMP2 with a Ki value and ΔGbinding score of 209.92 fM and −17.30 kcal/mol, respectively. This flavonoid was able to restrict MMP2 activity within a femtomolar range. This study identified eight flavonoids with Ki values in the picomolar range. According to the study, the docked pose of kaempferol 3-rutinoside-7-sophoroside within the MMP2 catalytic domain reached stability after a simulation of ~60 nanoseconds. Conclusion: Inhibition of MMP2 by flavonoids, notably kaempferol derivatives, might be an effective therapeutic strategy for cancer treatment.

Effects of peptides and probiotics supplementation via diet on blood parameters and growth performance of Piaractus brachypomus during the growth-out phase.

There is no evidence of peptides-probiotics symbiosis as supplements in aquafeeds. To evaluate the effect of peptides and probiotics supplementation via diet on blood parameters and growth performance of juvenile Piaractus brachypomus, an Amazonian fish, during the growth-out phase. 120 juvenile P. brachypomus (242.77 g) were placed into twelve 200-l tanks (10 fish/tank), housed in an indoor open system with constant water renovation (flow rate:1.50 l/minute). The experiment used a completely randomized design with a 4 × 5 factorial arrangement [4 doses of supplementation (CD: commercial diet; PepD: CD+1.50% of peptides per CD weight; ProD: CD+40.00 ml of activated probiotics per kg of diet (Lactobacillus spp., Rhodopseudomonas spp., Saccharomycetes spp.); PepProD: CD+Pep+Pro); 5 sampling times (zero, second, fourth, sixth, and eighth week); n = 3]. Fish were fed twice a day at a feeding rate of 1% of body weight. At each sampling time, blood was collected and fish were measured for growth performance analysis. Data were analyzed by using two-way ANOVA and Tukey's test (p < 0.05). The values of hematocrit (18.31%), leukocytes (1,216.67 mm3), neutrophils (81.27%), lymphocytes (18.73%), albumin (1.08 g/dl), relative growth rate (1.002%/day), and the Fulton allometric condition factor (2.03) remained constant throughout the experiment (p > 0.05). Plasma glucose decreased for all fish in the second week (59.56 mg/dl); then, that level increased in fish fed with the CD (89.00 mg/dl), while fish fed with PepD, ProD, and PepProD showed constant values (57.22 mg/dl). The plasma protein levels were constant in fish fed with the PepD and PepProD, (p > 0.05), while fish fed with the CD and ProD showed non-constant and higher values. At the end of the trial, fish fed with the PepProD showed the highest weight gain and the lowest feed conversion rate (39.66 g; 0.97). It is possible to maintain the stability of plasma glucose and plasma protein by supplementing diets with peptides, but the peptides-probiotics symbiosis administrated via diet contributes to maintaining the stability of plasma glucose and plasma protein and to improve the growth performance of juvenile P. brachypomus during the growth-out phase.

Interactions between quercetin and surfactants/solvents

The quercetin/surfactant/solvent systems are investigated using UV–VIS techniques. The reversed micelles (empty and containing water in their core) formed by Dioctyl sodium sulfosuccinate and Tween 60 (surfactants) in 1,4-dioxane and acetone (solvents) have been used to mimic in a simple way certain structural aspects of natural membranes, especially their hydrophobic parts. The micellar solutions were employed to study interactions with quercetin to check its location in micelles. Obtained results allowed to point that the quercetin molecules’ preferred location in studied micelles is palisade layer. Furthermore, the distribution constant, and binding constant values of quercetin in the examined systems have been calculated.

Complex viscosity and cohesive energy density of mixtures of sodium hyaluronate and hypromellose for medical devices

In the present study binary formulations of sodium hyaluronate (▪) and hypromellose (▪) were proposed as medical devices in the field of eye surgeries. Viscoelasticity is tested directly on binary solutions while the rheological behavior in the human eye is mimicked by monitoring the viscoelasticity of ternary mixtures ▪/▪/▪. Both binary and ternary formulations were rheologically characterized at 25∘C and 37∘C by means of measurements in the oscillatory regime. Amplitude sweep tests revealed that the range of linear viscoelasticity is strongly dependent on the concentration of ▪. For the proposed formulations, it was ascertained that the cohesive energy density at 37∘C decreases as ▪ concentration surges; in contrast, at 25∘C we detected an increase of cohesive energy were detected. At ▪ mass fraction of α1, the two obtained values were comparable. Frequency sweep tests revealed the pseudoplastic character of the binary formulations. In order to fit the complex viscosity modules, the Carreau-Yasuda model was modified. Numerical analysis of the results indicates that the best-fit to the model is obtained when the characteristic parameters take constant values, i.e. n=0 and m=1, regardless of the composition of the formulation. This implies that the modulus of complex viscosity decays hyperbolically. Frequency sweep tests on the ternary formulations were analyzed in terms of both the modulus of complex viscosity to confirm the previous scientific evidence together with an investigation of the phase shift angle between the viscous and elastic components. The results indicate that the addition of water has a different impact on the structure and the cohesion of the mixture at different temperatures. These results suggest that the ternary mixture structure can be sensitively modulated by temperature and the content of water.

Adaptive continuation based smooth -norm approximation for compressed sensing MR image reconstruction.

There are a number of algorithms for smooth -norm (SL0) approximation. In most of the cases, sparsity level of the reconstructed signal is controlled by using a decreasing sequence of the modulation parameter values. However, predefined decreasing sequences of the modulation parameter values cannot produce optimal sparsity or best reconstruction performance, because the best choice of the parameter values is often data-dependent and dynamically changes in each iteration. We propose an adaptive compressed sensing magnetic resonance image reconstruction using the SL0 approximation method. The SL0 approach typically involves one-step gradient descent of the SL0 approximating function parameterized with a modulation parameter, followed by a projection step onto the feasible solution set. Since the best choice of the parameter values is often data-dependent and dynamically changes in each iteration, it is preferable to adaptively control the rate of decrease of the parameter values. In order to achieve this, we solve two subproblems in an alternating manner. One is a sparse regularization-based subproblem, which is solved with a precomputed value of the parameter, and the second subproblem is the estimation of the parameter itself using a root finding technique. The advantage of this approach in terms of speed and accuracy is illustrated using a compressed sensing magnetic resonance image reconstruction problem and compared with constant scale factor continuation based SL0-norm and adaptive continuation based -norm minimization approaches. The proposed adaptive estimation is found to be at least twofold faster than automated parameter estimation based iterative shrinkage-thresholding algorithm in terms of CPU time, on an average improvement of reconstruction performance 15% in terms of normalized mean squared error. An adaptive continuation-based SL0 algorithm is presented, with a potential application to compressed sensing (CS)-based MR image reconstruction. It is a data-dependent adaptive continuation method and eliminates the problem of searching for appropriate constant scale factor values to be used in the CS reconstruction of different types of MRI data.