Isothermal Volume Research Articles

Delivering Volumetric Hyperthermia to Head and Neck Cancer Patient-Specific Models Using an Ultrasound Spherical Random Phased Array Transducer.

In exploring adjuvant therapies for head and neck cancer, hyperthermia (40-45 °C) has shown efficacy in enhancing chemotherapy and radiation, as well as the delivery of liposomal drugs. Current hyperthermia treatments, however, struggle to reach large deep tumors uniformly and non-invasively. This study investigates the feasibility of delivering targeted uniform hyperthermia deep into the tissue using a non-invasive ultrasound spherical random phased array transducer. Simulations in 3D patient-specific models for thyroid and oropharyngeal cancers assessed the transducer's proficiency. The transducer consisting of 256 elements randomly positioned on a spherical shell, operated at a frequency of 1 MHz with various phasing schemes and power modulations to analyze 40, 41, and 43 °C isothermal volumes and the penetration depth of the heating volume, along with temperature uniformity within the target area using T10, T50, and T90 temperatures, across different tumor models. Intensity distributions and volumetric temperature contours were calculated to define moderate hyperthermia boundaries. The results indicated the array's ability to produce controlled heating volumes from 1 to 48 cm3 at 40 °C, 0.35 to 27 cm3 at 41 °C, and 0.1 to 8 cm3 at 43 °C. The heating depths ranged from 7 to 39 mm minimum and 52 to 59 mm maximum, measured from the skin's inner surface. The transducer, with optimal phasing and water-cooled bolus, confined the heating to the targeted regions effectively. Multifocal sonications also improved the heating homogeneity, reducing the length-to-diameter ratio by 38% when using eight foci versus a single one. This approach shows potential for treating a range of tumors, notably deep-seated and challenging oropharyngeal cancers.

General Trends in the Compression of Glasses and Liquids

The present work relates the isothermal volumes of silicate glasses and melts to the combined ionic volumes of their chemical constituents. The relation is an extension of a relation that has already been established for crystalline oxides, silicates, alumosilicates, and other materials that have O2− as a constituent anion. The relation provides constraints on bond coordination, indicates pressure-induced changes in coordination in melts and glasses and interatomic distances, and quantifies the extent of transitory regions in pressure-induced coordination changes.

Structural Consequences of Different Metal Compositions in the Doped Spin‐Crossover Crystals [FezM1−z(bpp)2][BF4]2 (M = Ni, Zn; bpp = 2,6‐Bis{pyrazol‐1‐yl}pyridine)

Variable temperature crystallographic characterization of [FezZn1‒z(bpp)2][BF4]2 (bpp = 2,6‐bis{pyrazol‐1‐yl}pyridine; z = 0.88, 0.72 and 0.27) and [FezNi1‒z(bpp)2][BF4]2 (z = 0.83, 0.72 and 0.32) is presented. Comparison with previously published data confirms the isothermal unit cell volume change during spin‐crossover (ΔVSCO) behaves differently in the Zn‐ and Ni‐doped crystals. For the FeZn crystals, the relationship between ΔVSCO and z is continuous for z ≥ 0.3 but is steeper than expected, so ΔVSCO ≈ 0 for z = 0.27. In contrast ΔVSCO in the FeNi materials shows only a small variation between 0.83 ≥ z ≥ 0.46, before decreasing more strongly at higher dilution. ΔVSCO in each FeZn crystal is smaller than for its FeNi analogue with a similar composition. As well as the dopant ion ionic radius, the smaller ΔVSCO for the Zn‐doped materials reflects their T½ values, which are lower than for their FeNi counterparts. The contribution of T½ to this behavior is especially evident at high metal dilution.

Systematic thermodynamic and experimental studies for recovering indium and tin from indium tin oxide waste target with hydrogen

Resource utilization of waste indium tin oxide (ITO) can not only avoid the hazards of electronic waste, but also realize the recycling of dispersed metal indium (In). However, the current carbon thermal reduction process has the problems of high energy consumption and large carbon emissions. In this study, the feasibility and specific advantages of hydrogen reduction of waste ITO were explored by using high energy density and non-polluting H2 as reducing agent. The reduction process was thermodynamically analyzed by isothermal equation and molecular interaction volume model (MIVM), and the thermodynamic analysis results were verified by systematic experimental study. Experimental results showed that the reduction ratio of waste ITO can reach 99.43% under optimal conditions of 1173 K, 120 min, and 0.3 mol/L H2 flow rate, which indicated that the reduction process is feasible and efficient. Compared with vacuum carbothermal reduction process, hydrogen reduction process can reduce carbon emissions from the source, and theoretical energy consumption can be reduced by 70.12%. This work proposes a new method for recycling waste ITO that can reduce energy consumption and carbon emissions, providing further opportunities for the recycling of indium resources and the green economy of the electronics industry.

PVT Properties of Binary Systems of Poly(ethylene glycol mono-4-octylphenyl ether) with Anisole or Benzyl Alcohol at Pressures up to 50 MPa

Densities were determined experimentally for the binary mixtures of poly(ethylene glycol mono-4-octylphenyl ether) (PEGOPE) + anisole or benzyl alcohol at 298.15–348.15 K and pressures from 0.1 to 50 MPa. All of the excess volumes are negative over the whole experimental conditions, indicating that the hydrogen-bonding effect is dominant in these two binary systems. Those isothermal and isobaric excess volumes correlate well with the Redlich–Kister equation. The specific volumes of the pure components and their mixtures were correlated with the Schotte and Flory–Orwoll–Vrij (FOV) equations of state to average absolute relative deviations (AARDs) no greater than 0.03%.

Evidence of Self-Association and Conformational Change in Nisin Antimicrobial Polypeptide Solutions: A Combined Raman and Ultrasonic Relaxation Spectroscopic and Theoretical Study

The polypeptide Nisin is characterized by antibacterial properties, making it a compound with many applications, mainly in the food industry. As a result, a deeper understanding of its behaviour, especially after its dissolution in water, is of the utmost importance. This could be possible through the study of aqueous solutions of Nisin by combining vibrational and acoustic spectroscopic techniques. The velocity and attenuation of ultrasonic waves propagating in aqueous solutions of the polypeptide Nisin were measured as a function of concentration and temperature. The computational investigation of the molecular docking between Nisin monomeric units revealed the formation of dimeric units. The main chemical changes occurring in Nisin structure in the aqueous environment were tracked using Raman spectroscopy, and special spectral markers were used to establish the underlying structural mechanism. Spectral changes evidenced the presence of the dimerization reaction between Nisin monomeric species. The UV/Vis absorption spectra were dominated by the presence of π → π* transitions in the peptide bonds attributed to secondary structural elements such as α-helix, β-sheets and random coils. The analysis of the acoustic spectra revealed that the processes primarily responsible for the observed chemical relaxations are probably the conformational change between possible conformers of Nisin and its self-aggregation mechanism, namely, the dimerization reaction. The activation enthalpy and the enthalpy difference between the two isomeric forms were estimated to be equal to ΔH1* = 0.354 ± 0.028 kcal/mol and ΔH10 = 3.008 ± 0.367 kcal/mol, respectively. The corresponding thermodynamic parameters of the self-aggregation mechanism were found to be ΔH2* = 0.261 ± 0.004 kcal/mol and ΔH20 = 3.340 ± 0.364 kcal/mol. The effect of frequency on the excess sound absorption of Nisin solutions enabled us to estimate the rate constants of the self-aggregation mechanism and evaluate the isentropic and isothermal volume changes associated with the relaxation processes occurring in this system. The results are discussed in relation to theoretical and experimental findings.

NMR Studies of Aromatic Ring Flips to Probe Conformational Fluctuations in Proteins.

Aromatic residues form a significant part of the protein core, where they make tight interactions with multiple surrounding side chains. Despite the dense packing of internal side chains, the aromatic rings of phenylalanine and tyrosine residues undergo 180° rotations, or flips, which are mediated by transient and large-scale "breathing" motions that generate sufficient void volume around the aromatic ring. Forty years after the seminal work by Wagner and Wüthrich, NMR studies of aromatic ring flips are now undergoing a renaissance as a powerful means of probing fundamental dynamic properties of proteins. Recent developments of improved NMR methods and isotope labeling schemes have enabled a number of advances in addressing the mechanisms and energetics of aromatic ring flips. The nature of the transition states associated with ring flips can be described by thermodynamic activation parameters, including the activation enthalpy, activation entropy, activation volume, and also the isothermal volume compressibility of activation. Consequently, it is of great interest to study how ring flip rate constants and activation parameters might vary with protein structure and external conditions like temperature and pressure. The field is beginning to gather such data for aromatic residues in a variety of environments, ranging from surface exposed to buried. In the future, the combination of solution and solid-state NMR spectroscopy together with molecular dynamics simulations and other computational approaches is likely to provide detailed information about the coupled dynamics of aromatic rings and neighboring residues. In this Perspective, we highlight recent developments and provide an outlook toward the future.

Exploring the influence of urea on the proton-transfer reaction in aqueous amine solutions with Raman and ultrasonic relaxation spectroscopy

A combined ultrasonic and vibrational spectroscopic approach is performed, which allows measuring all the kinetic and thermodynamic parameters associated with the proton-transfer mechanisms taking place in the ternary urea- 1,1,3,3-tetramethylguanidine (TMG) -water system. The addition of urea affects extensively the already existing proton-transfer reaction that occurs when guanidine is dissolved in water. An almost perfect agreement is found between measured sound absorption dispersion and that predicted by a single Debye-type relaxation process, which can be attributed to the protonation reaction of either urea or guanidine. The experimental and theoretically predicted Raman spectra confirm the protonation of urea when added in the guanidine-water binary system. By comparing the relaxation spectra obtained for urea and amine, we observe a difference in the amplitude by several orders of magnitude, which means that since urea is the one with the higher amplitude, its protonation is the dominant contribution in the acoustic spectra of the ternary system. From the isothermal standard volume change in the ternary system with increasing urea concentration, the concentration dependence of the sound velocity, density, kinematic viscosity and classical absorption coefficient, it is evident that the addition of urea makes it difficult for the water molecules to accommodate the molecules of TMG. Urea restrains more water molecules away from the amine and breaks down the associated network of the binary system driving it to a less rigid one.

Direct observation of reversible liquid–liquid transition in a trehalose aqueous solution

Water forms two glassy waters, low-density and high-density amorphs, which undergo a reversible polyamorphic transition with the change in pressure. The two glassy waters transform into the different liquids, low-density liquid (LDL) and high-density liquid (HDL), at high temperatures. It is predicted that the two liquid waters also undergo a liquid-liquid transition (LLT). However, the reversible LLT, particularly the LDL-to-HDL transition, has not been observed directly due to rapid crystallization. Here, I prepared a glassy dilute trehalose aqueous solution (0.020 molar fraction) without segregation and measured the isothermal volume change at 0.01 to 1.00 GPa below 160 K. The polyamorphic transition and the glass-to-liquid transition for the high-density and low-density solutions were examined, and the liquid region where both LDL and HDL existed was determined. The results show that the reversible polyamorphic transition induced by the pressure change above 140 K is the LLT. That is, the transition from LDL to HDL is observed. Moreover, the pressure hysteresis of LLT suggests strongly that the LLT has a first-order nature. The direct observation of the reversible LLT in the trehalose aqueous solution has implications for understanding not only the liquid-liquid critical point hypothesis of pure water but also the relation between aqueous solution and water polyamorphism.

Isothermal crystallization behavior of undercooled liquid Pd40Cu30Ni10P20 in terms of crystal growth, overall volume crystallization kinetics and their relation to the viscosity temperature dependence

Abstract The crystallization behavior of undercooled liquid Pd40Cu30Ni10P20 metallic alloy has been studied with the aid of differential scanning calorimetry, optical metallography, and electron microscopy methods. The crystallization occurs as a single-stage process starting preferably on the surface of casting voids in the sample volume and on the outer sample cutting planes. The linear crystal growth velocity of crystallizing cells was measured at several constant temperatures in the range 590 –620 K. It is constant at constant temperatures and its temperature dependence is in good agreement with the theoretical concepts of Uhlmann using the temperature dependence of the viscosity of the alloy studied. A differential scanning calorimetry study of isothermal overall volume transformation kinetics of samples pre-annealed at 600 K for 600 s was carried out at several constant temperatures. The experimental data are interpreted on the basis of the equation of Kolmogorov-Avrami-Johnson-Mehl for the case of three-dimensional growth of a fixed number of pre-existing nuclei. The possibility to revitrify the crystallized samples by their melting in differential scanning calorimeter, followed by quick cooling with cooling rate of 5 K τ– 1 is shown. The volume transformation kinetics of revitrified samples has been also studied.

Deployable ultrasound applicators for endoluminal delivery of volumetric hyperthermia

Purpose To investigate the design of an endoluminal deployable ultrasound applicator for delivering volumetric hyperthermia to deep tissue sites as a possible adjunct to radiation and chemotherapy. Method This study considers an ultrasound applicator consisting of two tubular transducers situated at the end of a catheter assembly, encased within a distensible conical shaped balloon-based reflector that redirects acoustic energy distally into the tissue. The applicator assembly can be inserted endoluminally or laparoscopically in a compact form and expanded after delivery to the target site. Comprehensive acoustic and biothermal simulations and parametric studies were employed in generalized 3D and patient-specific pancreatic head and body tumor models to characterize the acoustic performance and evaluate heating capabilities of the applicator by investigating the device at a range of operating frequencies, tissue acoustic and thermal properties, transducer configurations, power modulation, applicator positioning, and by analyzing the resultant 40, 41, and 43 °C isothermal volumes and penetration depth of the heating volume. Intensity distributions and volumetric temperature contours were calculated to define moderate hyperthermia boundaries. Results Parametric studies demonstrated the frequency selection to control volume and depth of therapeutic heating from 62 to 22 cm3 and 4 to 2.6 cm as frequency ranges from 1 MHz to 4.7 MHz, respectively. Width of the heating profile tracks closely with the aperture. Water cooling within the reflector balloon was effective in controlling temperature to 37 °C maximum within the luminal wall. Patient-specific studies indicated that applicators with extended OD in the range of 3.6–6.2 cm with 0.5–1 cm long and 1 cm OD transducers can heat volumes of 1.1–7 cm3, 3–26 cm3, and 3.3–37.4 cm3 of pancreatic body and head tumors above 43, 41, and 40 °C, respectively. Conclusion In silico studies demonstrated the feasibility of combining endoluminal ultrasound with an integrated expandable balloon reflector for delivering volumetric hyperthermia in regions adjacent to body lumens and cavities.

Heat transportation enrichment and elliptic cylindrical solution of time-dependent flow

The main focus of this article is to examine the effects of heat transfer for a compressible time-dependent laminar flow pass the two distinctly positioned elliptic cylinders. The Mac number is chosen below 0.3 to keep the flow laminar. The heat transfer feature has been added and coupled with the laminar flow. The heat transfer feature adjusted for constant pressure. The arising Naiver-Stokes equations have been addressed numerically. The mesh has also been created and its entities have been elaborated statistically. The outcomes of velocity distribution, pressure distribution, 2D temperature plots, isothermal contours, drag coefficient, streamlines, and surface volume of fluid are discussed. The BDF technique has been employed to tackle the problem numerically. It was observed that the velocity profile at the boundaries of the elliptic cylinder has a maximum value, 3.85 m/s. The pressure distribution is observed maximum around elliptic cylinders. The heat transfer coefficient has maximum values at the upper and lower boundaries, the maximum temperature value observed is 290K. The isothermal contours, streamlines, and velocity volume were also studied. The drag coefficient is observed increasing but the drag force is decreasing. The mathematical modeling of the current problem has been designed in COMSOL.

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Woodceramics are porous carbon or hybrid materials, derived from woody materials impregnated with a thermosetting resin and vacuum carbonized at a high temperature. Woodceramics have become commercially valuable as these are used in many appliances such as heaters, gas filters, absorbents, humidity and temperature sensors. Hence, this study aimed to determine the suitable conditions for producing woodceramics from various materials and their potential applications. The Specific Surface Area (SSA), pore volume, pore diameter, and adsorption isotherm of woodceramics made from Bamboo, Pine, Eucalyptus, Rubberwood, and Oil Palm shell particleboards were obtained using the Brunauer-Emmett-Teller (BET) method. The average pore diameter is classified as being mesoporous (2-50 nm). The SSA and adsorption isotherm results of the woodceramics made from Eucalyptus showed that these species can be used as an activated charcoal and their volume electrical resistivity is similar to that of a semiconductor. When carbonized at maximum temperatures of 800 °C and 1,000 °C, the electromagnetic shielding effectiveness (ESE) of woodceramics was approximately 20-60 dB within a frequency range of 800-2,200 MHz. This ESE   was higher than that woven from boron carbon fiber, carbon boron, and stainless steel fiber filled thermoplastics. Moreover, the woodceramics production cost was lower than that of using the commercial materials.Â

Effect of dilution of nonpolar solvents (CCl4 and C6H6) on densities and excess molar volumes of methanol + 1-butanol mixtures over the temperature range 293.15–308.15 K

Methanol and 1-butanol have philicity to each other but their binary mixing features were very rarely discussed. Non-linear density-composition plots of methanol + 1-butanol (M-B) binary mixtures indicates non-ideal mixing of the two alcohols. Excess molar volume (VmE) remains positive over the entire composition range. The VmE isotherms in the temperature range from 293.15 K to 308.15 K are measured at 5 K intervals exhibit maxima at xmethanol ~ 0.6, indicating maximum no of H-Bonds among the solvents are formed at this composition. No change in maxima position indicate no significant structural change with temperature. Due to different sizes of alkyl groups “hydrophobic-like” interactions for methanol have been proposed to explain positive VmE. Neat 1-butanol when diluted with CCl4 or C6H6 (nonpolar diluents) exhibits positive VmE is an indication of segregation of its molecules due to their weak mutual interactions. On the other hand, negative VmE for methanol upon adding the diluents suggests oligomer formation in it. Also, the binary mixtures of the alcohol and the diluents addition to neat alcohols results in non-linear density isotherms for methanol and negative VmE while for butanol, linear density isotherms and positive VmE was observed. This behavior should suggest that M-B molecules do not tend to congregate with each other rather methanol-methanol (M-M) association is preferred.

Study and optimization of Diels-Alder reaction of piperine in aqueous ionic solutions using Gn.HCl as a catalyst

Study and optimization of Diels-Alder reaction of piperine in aqueous ionic solutions using Gn.HCl as a catalyst

Entropic analysis of bistability and the general evolution criterion.

We present a detailed study of the entropy production, the entropy exchange and the entropy balance for the Schlögl model of chemical bi-stability for both the clamped and volumetric open-flow versions. The general evolution criterion (GEC) is validated for the transitions from the unstable to the stable non-equilibrium stationary states. The GEC is the sole theorem governing the temporal behavior of the entropy production in non-equilibrium thermodynamics, and we find no evidence for supporting a "principle" of maximum entropy production. We use stoichiometric network analysis (SNA) to calculate the distribution of the entropy production and the exchange entropy over the elementary flux modes of the clamped and open-flow models, and aim to reveal the underlying mechanisms of dissipation and entropy exchange.

A Thermophysical Perspective of the Inter-relationship between Debye Temperature and Electron Density

A comprehensive thermophysical analysis of the linkage between the Debye temperature θD and electron density ne has been presented. Assuming that the Debye cut-off frequency ωD is related to the effective oscillation frequency ω of screened ion cores of a metallic material, a simple analytical relationship could be established between θD, bonding electron density ne, and materials density ρm. Alternately, it is possible to establish a consistent set of electron density n e values using θD, which in the case of pure metals is shown to exhibit a linear scaling with Miedema’s thermochemical electron density n e M values. The temperature, pressure, and composition dependencies of θD are addressed uniformly in terms of isobaric and isothermal volume variations of ne; besides, invoking the subregular solution formalism for expressing composition-induced molar volume variation simple approximations for melting temperature Tm and vibrational entropy $$ S_{T}^{\text{o}} $$ have been suggested in terms of electron density. Estimates of θD, $$ S_{298}^{\text{o}} $$ , and average sound velocity have been obtained for metastable bcc U1−xZrx solid solution.

DEVELOPMENT OF WOODCERAMICS FROM TROPICAL FLORA

Woodceramics are porous carbon or hybrid materials, derived from woody materials impregnated with a thermosetting resin and vacuum carbonized at a high temperature. Woodceramics have become commercially valuable as these are used in many appliances such as heaters, gas filters, absorbents, humidity and temperature sensors. Hence, this study aimed to determine the suitable conditions for producing woodceramics from various materials and their potential applications. The Specific Surface Area (SSA), pore volume, pore diameter, and adsorption isotherm of woodceramics made from Bamboo, Pine, Eucalyptus, Rubberwood, and Oil Palm shell particleboards were obtained using the Brunauer-Emmett-Teller (BET) method. The average pore diameter is classified as being mesoporous (2-50 nm). The SSA and adsorption isotherm results of the woodceramics made from Eucalyptus showed that these species can be used as an activated charcoal and their volume electrical resistivity is similar to that of a semiconductor. When carbonized at maximum temperatures of 800 °C and 1,000 °C, the electromagnetic shielding effectiveness (ESE) of woodceramics was approximately 20-60 dB within a frequency range of 800-2,200 MHz. This ESE   was higher than that woven from boron carbon fiber, carbon boron, and stainless steel fiber filled thermoplastics. Moreover, the woodceramics production cost was lower than that of using the commercial materials.Â

Силы, порождающие кристаллизационную дифференциацию, и эволюция состава расплава на примере плагиоклаза

Crystallization differentiation processes in the melt volume are investigated for albite-anorthite continuous solid solution series. It has shown that crystallization differentiation occurs in the isothermal melt volume due to hydrodynamic instability of the melt/solid particles system. The time of particle settling in a 10 cm thick melt layer is estimated for different particle sizes. In terrestrial conditions, the existence of large melt volumes with long lifetime is possible in the case of a long-lived heat source of high thermal power. This source is a mantle thermochemical plume with a mushroom-shaped head. The particle settling time is estimated for the melt layer thickness, i. e. plume head thickness equal to 10 km. A calculation technique is presented for composition of the melt remaining after settling of plagioclase particles. The results of calculations of changes in the melt composition due to crystallization differentiation at a temperature T = 1410 °C and a pressure P = 6,3 kbar are presented. For a melt whose composition corresponds to N 47,5 (weight percentage of anorthite is 47,5 %), the oxide content in the settled plagioclase, the composition of the melt in its intercrystalline spaces, and the residual melt composition are calculated. At constant temperature, the crystallization differentiation of the melt whose composition corresponds to plagioclase leads to the compositional changes in the initial melt. Calculations of the melt composition have shown that the melt is depleted in anorthite component owing to settling of plagioclase particles. The composition of plagioclase therewith shifts to the liquidus line, reaching its limit on this line

Describing function of the pneumatic flapper-nozzle valve

Abstract This paper addresses the mass flow rate characteristic of a pneumatic valve set in the frequency domain. The valve set consists of a flapper-nozzle type valve and a constant isothermal volume chamber. It represents a part of the control system of the pneumatic parallel robot platform. Different flow regimes are analyzed because of air compressibility. The nonlinearity originating from the mass flow rate characteristic is approximated by the sinusoidal input describing function. Analytical determination of the describing function in a general case is not possible. However, the equivalent nonlinearity and the corresponding Hammerstein model can be introduced for a certain flow regime. In that case, the describing function of nonlinearity can be determined analytically. Amplitude and frequency responses show that the nonlinearity becomes more prominent at smaller frequencies and higher amplitudes of the exogenous signal. Analytical results show good agreement with the experimental results.