Varying Volume Ratios Research Articles

A Thermodynamic Approach for Assessing the Environmental Exposure of Chemicals Absorbed to Microplastic

The environmental distribution and fate of microplastic in the marine environment represents a potential cause of concern. One aspect is the influence that microplastic may have on enhancing the transport and bioavailability of persistent, bioaccumulative, and toxic substances (PBT). In this study we assess these potential risks using a thermodynamic approach, aiming to prioritize the physicochemical properties of chemicals that are most likely absorbed by microplastic and therefore ingested by biota. Using a multimedia modeling approach, we define a chemical space aimed at improving our understanding of how chemicals partition in the marine environment with varying volume ratios of air/water/organic carbon/polyethylene, where polyethylene represents a main group of microplastic. Results suggest that chemicals with log KOW > 5 have the potential to partition >1% to polyethylene. Food-web model results suggest that reductions in body burden concentrations for nonpolar organic chemicals are likely to occur for chemicals with log KOW between 5.5 and 6.5. Thus the relative importance of microplastic as a vector of PBT substances to biological organisms is likely of limited importance, relative to other exposure pathways. Nevertheless, a number of data-gaps are identified, largely associated with improving our understanding of the physical fate of microplastic in the environment.

Electrochemical characterization and photovoltaic performance of the binary ionic liquid electrolyte of 1-methyl-3-propylimidazolium iodide and 1-ethyl-3-methylimidazolium tetrafluoroborate for dye-sensitized solar cells

Determination of triiodide diffusion coefficient, charge-transfer resistance and photovoltaic performance of the binary ionic liquid electrolyte of 1-methyl-3-propylimidazolium iodide (MPII) and 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF 4) for dye-sensitized solar cells (DSSCs) were performed at varying volume ratios of MPII/EMIMBF 4. Compared to pure MPII ionic liquid, the addition of EMIMBF 4 not only increased triiodide diffusion coefficient, but also decreased charge-transfer resistance at Pt/electrolyte interface, leading to the notably improved photovoltaic performance of DSSC. The highest photoelectric conversion efficiency of 4.99% was obtained under light intensity of 100 mW/cm 2 for the DSSC with the binary MPII/EMIMBF 4 ionic liquid electrolyte when the volume ratio of MPII/EMIMBF 4 was 50/50, which was much higher than that of pure MPII ionic liquid electrolyte (2.6%).

Experimental study of internal acoustic field generated by oil separator component of refrigeration cycle

Compressed air experiments are conducted to investigate the internal acoustic field generated by the simple top insert edge and the oil separator model of refrigeration cycle system. The acoustic characteristic of flow through the insert edge was found to be broadband with no discrete tones. Furthermore, some tones were captured in the internal oil separator model but the insert edge had no impact on these whistle peaks. Different whistle tone modes are captured with the varying volume ratios (VRs) of oil separator model. These whistle peaks are not related to the resonance of oil separator model but agreed well with the modes calculated by the Rossiter's modified formula. The whistle noise generation mechanism is regarded to be a feedback loop of flow-acoustic interaction in the fluctuated shear layer.

Oxidation-reduction potential in saline water reverse osmosis membrane desalination and its potential use for system control

Chlorination and dechlorination are required in most saline water (brackish and seawater) reverse osmosis membrane desalination processes, regardless of whether a membrane or conventional chemical conditioning is employed as a pre-treatment. Wastage of chemicals occurs when the dosing process is not automated. Titrations of chlorinated water (using sodium hypochlorite) with sodium meta-bisulfite were undertaken using water of different salinities, which were obtained by varying volume ratios of seawater to deionized water (4:0, 3:1, 2:2, 1:3 and 0:4). Changes in reduction and oxidation potential (ORP) were studied with variations in chlorine doses (0 to 5 mg L-1NaOCl) and salinities. As expected, the ORP values were greater at higher than at lower chlorine doses for any given water. The greater the ratio of seawater to deionized water, the lower was the ORP value, with a difference of greater than 100 mV between the deionised water and the seawater at a high chlorine dosage. The results suggest that the ORP level would be lower for seawater than for brackish water in control of chlorine dose. The ORP decreased with sodium meta-bisulfite addition at high chlorine dosages ≤2 mg l -1) while the opposite was observed at low chlorine dosages (≥1 mg L-1). Free chlorine disappeared instantly following sodium meta-bisulfite addition. As more than 80% of the added chlorine was diminished in the seawater, 2 mg L-1 sodium meta-biosulfite was sufficient to reduce free residual chlorine to less than 0.1 mg L-1 as required for most of the cellulose acetate RO membrane in seawater desalination. To be safe and cost-efficient, a chemical dose controller can be developed using the ORP titration information.

Shape- and Size-Dependent Refractive Index Sensitivity of Gold Nanoparticles

Gold nanoparticles of different shapes and sizes, including nanospheres, nanocubes, nanobranches, nanorods, and nanobipyramids, were dispersed into water-glycerol mixtures of varying volume ratios to investigate the response of their surface plasmon peaks to the refractive index of the surrounding medium. The refractive index sensitivities and figures of merit were found to be dependent on both the shape and the size of the Au nanoparticles. The index sensitivities generally increase as Au nanoparticles become elongated and their apexes become sharper. Au nanospheres exhibit the smallest refractive index sensitivity of 44 nm/RIU and Au nanobranches exhibit the largest index sensitivity of 703 nm/RIU. Au nanobipyramids possess the largest figures of merit, which increase from 1.7 to 4.5 as the aspect ratio is increased from 1.5 to 4.7.

Highly active mixed-phase TiO2 photocatalysts fabricated at low temperatureand the correlation between phase compositionand photocatalytic activity

The idea of varying volume ratio of water to ethanol in solvent was firstly employed to yield phase composition controllable mixed-phase titanium dioxide (TiO2) photocatalysts via a low temperature solvothermal route at 353 K. It was found that anatase contents increase from 0 to 100% with increase of ethanol contents in solvent. The mixed-phase TiO2 with 60% anatase content exhibited the best photocatalytic activity in photodecomposing formaldehyde (FAD) under UV light irradiation, which increases by about 270 or 400% in comparison with single rutile or anatase TiO2, and is slightly better than commercial mixed-phase TiO2 (P25). The synergistic effect in mixed-phase TiO2 including antenna effect by rutile phase and the activation effect by anatase phase was observed. Further, partially quantitive correlation between phase composition and photocatalytic activity was ascribed to maximizing the synergistic effect and an optimal value of anatase content about 60% in mixed-phase TiO2 photocatalyst was therefore suggested.

Donnan dialysis with anion-exchange membranes in a water desalination system

Donnan dialysis with an anion-exchange membrane is proposed as a pretreatment step in a water desalination system. The process replaces anions that cause the precipitation of sediments with neutral chloride anions. Water after Donnan dialysis mainly contains soluble chloride salts that should cause no scaling problems during electrodialytic desalination. The first part of the paper deals with Donnan dialysis of one- and multi-component solutions. Two anion-exchange membranes were examined with different concentrations of the receiver and varying volume ratio of the streams. The results show high efficiency of anion removal. Then, results of electrodialysis of the “raw” multi-component solution and the solution previously treated with Donann dialysis are presented and compared. Preliminary replacement of sulphates and bicarbonates with chloride anions ensures lower energy consumption and higher fluxes during subsequent electrodialysis. It also results in a shorter process time.

Method for Estimating Complex Permittivity Based on Measuring Effective Permittivity of Dielectric Mixtures in Radio Frequency Band

This paper proposes a method for estimating the complex permittivity of a small quantity of a sample such as a biological membrane. The feature of this method is that a material with art unknown complex permittivity is mixed with a material with a known complex permittivity in a number of volume ratios. The unknown complex permittivity is estimated by measuring the effective permittivity of the mixtures and by using the mixing formula, which is applied to the composite material. The validity of this estimation method is evaluated using a phospholipid, which is the primary constituent of a biological membrane, in the frequency range from 0.8 GHz to 6 GHz. We confirm that the measured effective permittivity of the phospholipid mixtures, which comprise the phospholipid and Ringer's solution in a number of volume ratios, corresponds to that of the Lichtenecker formula. Additionally, by preparing a number of samples with varying volume ratios the estimation error can be decreased. This estimation method is considered to be effective in the measurement of the complex permittivity for a biological membrane.

WE-E-J-6C-04: The Effect of Heterogeneous and Nonlinear Material Properties On Organ Deformation

Purpose: The purpose of this research is to investigate the effect of intra‐organ heterogeneous material properties on finite element model (FEM)‐based deformable image registration.Method and Materials: Heterogeneities were included in the organ of interest, the liver for this initial study, in two ways: 1) by randomly distributing spheres of varying size (diameter: 0.5 – 1.5 cm) and number (19 – 79) throughout the liver and 2) by creating a single sub‐volume of varying volume ratio (23 – 92%) by contracting the liver contour by varying amounts. A large number of simulation parameters were investigated, including Poisson's ratio (v = 0.2 – 0.499), elastic modulus (E = 1 – 100 kPa), and hyperelastic properties (0.1 – 660% variations corresponding to 1 – 100 kPa) for varying volume ratios (3 – 92%) of the heterogeneous volume. The Taguchi method was used to investigate the contribution of each parameter to the average difference between the deformations of heterogeneous liver and those of the reference homogeneous liver.Results: The contributions of Poisson's ratio of the liver and heterogeneous volume sharply decreased and exponentially increased, respectively, as a function of the volume ratio of heterogeneous volume. The maximum contribution (20 – 51%) of the elastic modulus of heterogeneous volume was exhibited at the volume ratio of 54 to 67%. The result also indicates that the maximum average differences and 3‐σ differences ranged from 1.2 to 2.4 mm (percent contribution: 28 – 55%) and 1.75 to 4.2 mm (percent contribution: 42 – 97%), respectively. Conclusion: This study indicates that the variations of the deformation by the material uncertainties are not negligible, but this parametric approach can be applied to extract the quantitative effects of the significant material parameters on the deformation of a heterogeneous liver having various material uncertainties. Conflict of Interest: Research supported in part by a grant from Varian Medical Systems.

Microencapsulation of human growth hormone within biodegradable polyester microspheres: Protein aggregation stability and incomplete release mechanism

Recombinant human growth hormone (rhGH) was encapsulated within poly(d,l-lactic-co-glycolic acid) microspheres by a double emulsion solvent evaporation method. A mixture of methylene chloride and ethyl acetate in varying volume ratios was used for the microsphere preparation. Protein release profiles from three different microsphere formulations demonstrated initial burst effects ranging from 28.2% to 54.7% after a 1-day incubation and exhibited no further significant releases up to 19 days. This was because the encapsulated rhGH with the microspheres was largely aggregated in a noncovalent fashion during the formulation. Nonaggregated water soluble rhGH species within the microspheres are likely to be responsible for the rapid release upon incubation. The initially released rhGH in the incubation medium, however, was composed of mostly monomer species with a small amount of dimer as probed by size-exclusion chromatography. Circular dichroism spectra of the initially released rhGH in the medium revealed that the conformation of the released rhGH was correctly folded relative to that of native rhGH, with little variation in α-helix contents depending on the formulations. The “nonrelease” mechanism after the initial burst release was attributed to nonspontaneously dissociable noncovalent protein aggregation and surface adsorption of rhGH present within the microspheres. © 1999 John Wiley & Sons, Inc. Biotechnol Bioeng 65: 659–667, 1999.

Microencapsulation of human growth hormone within biodegradable polyester microspheres: protein aggregation stability and incomplete release mechanism.

Recombinant human growth hormone (rhGH) was encapsulated within poly(D,L-lactic-co-glycolic acid) microspheres by a double emulsion solvent evaporation method. A mixture of methylene chloride and ethyl acetate in varying volume ratios was used for the microsphere preparation. Protein release profiles from three different microsphere formulations demonstrated initial burst effects ranging from 28.2% to 54.7% after a 1-day incubation and exhibited no further significant releases up to 19 days. This was because the encapsulated rhGH with the microspheres was largely aggregated in a noncovalent fashion during the formulation. Nonaggregated water soluble rhGH species within the microspheres are likely to be responsible for the rapid release upon incubation. The initially released rhGH in the incubation medium, however, was composed of mostly monomer species with a small amount of dimer as probed by size-exclusion chromatography. Circular dichroism spectra of the initially released rhGH in the medium revealed that the conformation of the released rhGH was correctly folded relative to that of native rhGH, with little variation in alpha-helix contents depending on the formulations. The "nonrelease" mechanism after the initial burst release was attributed to nonspontaneously dissociable noncovalent protein aggregation and surface adsorption of rhGH present within the microspheres.

Correlation of mass transfer coefficients for tellurium(IV) extraction with instantaneous reaction in a modified Lewis cell

Mass transfer of Te(IV) between an aqueous and organic phase was studied in a modified Lewis cell. The organic phase was composed of tri-n butyl phosphate as extractant in de-aromatized kerosene at varying volume ratios. Experimental data were correlated in the form of Sherwood number, Schmidt number of the aqueous phase and Reynolds number and viscosity ratio by dimensional analysis. The correlation obtained is: k 1L D =0.187Sc 0.33 1Re 0.97 μ 2 μ 1 1.6 1+ Re 2μ2 Re 1μ1

Analytical and preparative high-performance liquid chromatography of gangliosides.

Analytical and preparative procedures are described for high-performance liquid chromatography (HPLC) fractionation of gangliosides without previous derivatization. These procedures make use of a reversed-phase Lichrosorb RB-8 or mu Bondapak RP-18 column, and of a mixture of acetonitrile and 5 mM phosphate buffer, at fixed or varying volume ratios, as solvent system. Peak elution from the column is monitored by flow through reading of absorbance at 195 nm. Under all the described conditions HPLC is capable of resolving all common gangliosides and of separating each of them into four molecular species containing C18-sphingosine, C18-sphinganine, C20-sphingosine, or C20-sphinganine. The analytical method has been successfully applied to fractionation of ganglioside mixtures from calf brain and to verification of homogeneity of single-ganglioside preparations. It is suitable for quantitative purposes, with high sensitivity (detection limit, 0.1 nmole) and precision (SD less than 10% of mean values in the concentration range 0.1-50 nmoles). The semipreparative method, which provides successive cycles of analysis in a fully automated way, enables the preparation in 2-4 days of 100-mg amounts of each molecular species starting from single gangliosides, like GM1 and GD1a. The preparative method makes use of acetonitrile-phosphate buffer-tetrahydrofuran as eluting solvent, and requires the addition to the starting ganglioside of the corresponding radioactive compound as tracer. This procedure, applied to GM1 ganglioside, is devised for processing up to 50 mg of ganglioside per analysis.

A study of the compatibility of synthetic rubbers with phenolic resins

The compatibility has been studied of two types of synthetic rubbers with two types of phenolic resins by measuring the heat effect of mixing of their equiponderant solutions in varying volume ratios. The measurements were made in an adiabatic calorimeter. On the basis of the calorimeter curves obtained in the study, compatibility has been established for all the components under investigation over a wide range of ratios. It has also been demonstrated that the method is applicable to such mixtures independent of the volume ratio of the main components.

Preparation and properties of titanium arsenates

Amorphous titanium arsenates have been prepared by mixing solutions of titanic chloride and sodium arsenate of different concentrations and in varying volume ratios. The material prepared by mixing 0·05M titanic chloride and 0·05M sodium arsenate in the ratio 1 : 1 was studied in detail for its ion exchange capacity, stability, thermogravimetry, pH-titration curve and K d values. The structures of one sample was established tentatively and its utility demonstrated by separating Pb(II) from Cu(II), Zn(II), Mg(II) and Ga(III).