Dielectric Properties of Aqueous Ionic Solutions. Parts I and II

Hasted, J. B.; Ritson, D. M.; Collie, C. H.

doi:10.1063/1.1746645

Cited by 679 publications

(295 citation statements)

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“…Dielectric properties of a commercial apple juice product were also measured over the 200 MHz to 20 GHz frequency range (Nelson and Bartley 2002). The temperature dependence of the dielectric properties of the apple juice at the higher frequencies is also very similar to that of pure liquid water, with the relaxation frequency for pure water shifting from below 20 GHz to higher frequencies as temperature increases (Hasted 1973). The electrical resistance, gloss and weight of eggplant during storage were determined using a galvanometer, a spectroradiometer and a precision electronic balance, respectively (Jha et al 2004).…”

Section: Fruits and Vegetablesmentioning

confidence: 95%

“…For salt contents greater than 2%, the predicted ε″ increased with temperature, which is in accord with the behaviour of aqueous salt solutions. Hasted et al (1948), Sun et al (1995) Soy protein isolate 200-2500 MHz concentration (5, 10…”

Section: Factors Affecting the Dielectric Propertiesmentioning

confidence: 99%

“…Salt ions can also affect the dielectric properties significantly, especially the dielectric loss factor and it is useful to study the dielectric properties of salt solutions (Hasted et al 1948;Sun et al 1995). The dielectric constants of the salt solutions decreased as temperature increased.…”

Section: Dairy Productsmentioning

confidence: 99%

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Measurement techniques and application of electrical properties for nondestructive quality evaluation of foods—a review

et al. 2011

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Non-destructive systems are recent trends for quality evaluation of fruits and vegetables. Information on post-harvest variations in electrical properties is needed to develop new instruments for this purpose. Electrical properties are finding increasing application in agriculture and food processing industries. Knowledge of dielectric properties of foods as a function of moisture content and temperature is essential in the design and control of drying systems. As simple, rapid and non-destructive measuring techniques, dielectric spectroscopy provides information about the dielectric response of materials to electromagnetic field. Electrical properties of agricultural materials have been of interest for many years. The interest in dielectric properties of materials has historically been associated with the design of electrical equipment. This review paper covers theoretical aspects of different electrical properties, their measurement techniques, applications of dielectric properties in agriculture/food processing sector and potential applications of thermal imaging (TI) for quality and safety assessment in food processing. The values of dielectric properties of a number of products including food grains, fruits and vegetables, and meat and meat products are presented in table form. This comprehensive coverage will be useful for academic, scientific and industrial community in treating and applying the facts in developing/testing new processes and products based on electromagnetic energy application.Keywords Electrical properties . Non-destructive . Measuring techniques . Dielectric constant . Loss factor . Thermal imaging technique . Food quality evaluationThe material investigation and moisture measurement using electromagnetic waves in wide spectrum serve for quality control and improvement in many branches like industry, forest and wood-working industry, civil engineering, agriculture, commerce and also foods e.g. for quality evaluation of meat, fruits, coffee etc (Hlavacova 2003; Venkatesh and Raghavan 2004). Non-destructive evaluation of quality based on constituents of fruits and vegetables has been successfully used (Chen et al. 1999;Jha et al. 2001;Kawano 1998). Electrical characteristics of agricultural materials have been of interest for many years (Nelson 2006) and are utilized in many areas of human activities. Techniques for non-destructive determination of quality and related characteristics of agricultural products are helpful to producers, handlers and processors . Permittivity and moisture can be closely correlated when water content is high. Knowledge of dielectric properties in partially frozen material is critical in determining the rates and uniformity of heating in microwave thawing. Electrical properties are important in processing foods with pulsed electric fields, ohmic heating, induction heating, radio frequency, and microwave heating. These properties are also useful in the detection of processing conditions or the quality of foods (Barbosa-Canovas et al. 2006). Considering ...

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Section: Fruits and Vegetablesmentioning

confidence: 95%

Section: Factors Affecting the Dielectric Propertiesmentioning

confidence: 99%

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Measurement techniques and application of electrical properties for nondestructive quality evaluation of foods—a review

et al. 2011

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“…In our PF-VISM, we construct analytic forms of the dielectric coefficient ε = ε(φ) to mimic experimental data, allowing the asymmetry with respect to φ ≈ 0 for the solvent region and φ ≈ 1 for the solute region. 98 We shall demonstrate that this may be a first step toward a detailed description of solute-solvent interfacial structures using an implicit-solvent approach.…”

Section: Introductionmentioning

confidence: 99%

“…98 This is related to the basic issue of defining a dielectric boundary. There are different kinds of solute-solvent interfaces; and most of them are defined using the fluctuating solvent density.…”

Section: Introductionmentioning

confidence: 99%

A self-consistent phase-field approach to implicit solvation of charged molecules with Poisson–Boltzmann electrostatics

Sun

Wen

Zhao³

et al. 2015

The Journal of Chemical Physics

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Dielectric boundary based implicit-solvent models provide efficient descriptions of coarse-grained effects, particularly the electrostatic effect, of aqueous solvent. Recent years have seen the initial success of a new such model, variational implicit-solvent model (VISM) McCammon Phys. Rev. Lett. 96, 087802 (2006) and J. Chem. Phys. 124, 084905 (2006)], in capturing multiple dry and wet hydration states, describing the subtle electrostatic effect in hydrophobic interactions, and providing qualitatively good estimates of solvation free energies. Here, we develop a phase-field VISM to the solvation of charged molecules in aqueous solvent to include more flexibility. In this approach, a stable equilibrium molecular system is described by a phase field that takes one constant value in the solute region and a different constant value in the solvent region, and smoothly changes its value on a thin transition layer representing a smeared solute-solvent interface or dielectric boundary. Such a phase field minimizes an effective solvation free-energy functional that consists of the solute-solvent interfacial energy, solute-solvent van der Waals interaction energy, and electrostatic free energy described by the Poisson-Boltzmann theory. We apply our model and methods to the solvation of single ions, two parallel plates, and protein complexes BphC and p53/MDM2 to demonstrate the capability and efficiency of our approach at different levels. With a diffuse dielectric boundary, our new approach can describe the dielectric asymmetry in the solute-solvent interfacial region. Our theory is developed based on rigorous mathematical studies and is also connected to the Lum-Chandler-Weeks theory (1999). We discuss these connections and possible extensions of our theory and methods. C 2015 AIP Publishing LLC. [http://dx

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Fluorescence in Organized Assemblies

Hinze¹

2000

Encyclopedia of Analytical Chemistry

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This article provides an overview of the general properties of organized assembly (ordered media) systems such as aqueous surfactant and bile salt micelles, lipid and surfactant vesicles (liposomes) and cyclodextrins (CDs) and summarizes their utilization to enhance the performance of analytical fluorescence measurements. In many instances, organic molecules and metal complex species, when included within a CD cavity or solubilized and bound to surfactant aggregates, exhibit enhanced fluorescence. This gives rise to improved detectability of such analytes. The altered microenvironment within the organized medium is capable of impeding the interfering action of other species (inorganic or organic) present in the sample matrix. This often can improve the selectivity of the analytical method. These benefits of improved sensitivity and selectivity arise from the compartmentalization, isolation and shielding of the excited singlet state of the guest analyte from quenching and nonradiative decay processes as well as prevent side reactions that otherwise can occur in bulk solution (or sample matrix). In addition, organic solvents or time‐consuming extraction steps can be avoided owing to the increased solubility of the nonpolar organic or inorganic reagents and/or analyte molecules in water in the presence of the organized medium; allowing for the use of an aqueous medium to perform the procedure. The possibility of conducting reactions and forming fluorescent organic or metal chelates in micellar (or other organized) media that are not observed in a bulk homogeneous solvent system serves to expand the scope of chemistries that one can consider using to design/develop new, unique and improved fluorescent assays. Numerous representative examples of fluorescent methods for determination of both organic and inorganic analytes are provided which serve to illustrate the advantages and benefits accrued from the use of the micelles, vesicles, liposomes or CDs in such procedures. Some experimental considerations and cautions to keep in mind when utilizing organized media are also delineated. An extensive reference section is provided so that the interested reader can easily refer to such for more detailed information on these systems and topics.

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Dielectric Properties of Aqueous Ionic Solutions. Parts I and II

Cited by 679 publications

References 14 publications

Measurement techniques and application of electrical properties for nondestructive quality evaluation of foods—a review

Measurement techniques and application of electrical properties for nondestructive quality evaluation of foods—a review

A self-consistent phase-field approach to implicit solvation of charged molecules with Poisson–Boltzmann electrostatics

Fluorescence in Organized Assemblies

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