Increase In Ethylene Glycol Concentration Research Articles

Microscopic picture of water-ethylene glycol interaction near a model DNA by computer simulation: Concentration dependence, structure, and localized thermodynamics.

It is known that crowded molecular environment affects the structure, thermodynamics, and dynamics of macromolecules. Most of the previous works on molecular crowding have majorly focused on the behavior of the macromolecule with less emphasis on the behavior of the crowder and water molecules. In the current study, we have precisely focused on the behavior of the crowder, (ethylene glycol (EG)), salt ions, and water in the presence of a DNA with the increase of the EG concentration. We have probed the behavior of water and crowder using molecular dynamics (MD) simulation and by calculating localized thermodynamic properties. Our results show an interesting competition between EG and water molecules to make hydrogen bonds (H-bond) with DNA. Although the total number of H-bonds involving DNA with both EG and water remains essentially same irrespective of the increase in EG concentration, there is a proportional change in the H-bonding pattern between water-water, EG-EG, and EG-water near DNA and in bulk. At low concentrations of EG, the displacement of water molecules near DNA is relatively easy. However, the displacement of water becomes more difficult as the concentration of EG increases. The density of Na+ (Cl-) near DNA increases (decreases) as the concentration of EG is increased. The density of Cl- near Na+ increases with the increase in EG concentration. It was also found that the average free energy per water in the first solvation shell increases with the increase in EG concentration. Putting all these together, a microscopic picture of EG, water, salt interaction in the presence of DNA, as a function of EG concentration, has emerged.

The effect of ethylene glycol on pore arrangement of anodic aluminium oxide prepared by hard anodization.

The influence of the addition of ethylene glycol (EG) on the pore self-ordering process in anodic aluminium oxide (AAO) membranes prepared by hard anodization (HA) was investigated. It was illustrated that EG has a substantial effect on the pore arrangement of AAO, and it was found that a smaller pore size can be obtained with an EG concentration reaching 20 wt% in aqueous electrolyte. The number of estimated defects of AAO increases significantly with an increase in EG concentration to 50 wt%. Excellent ordering of pores was realized when the samples were anodized in the 30 wt%-EG-containing aqueous electrolyte.

The phase equilibria of multicomponent gas hydrate in methanol/ethylene glycol solution based formation water

In this paper, the three-phase coexistence points are generated for multicomponent gas hydrate in methanol (MeOH) solution for (0.05, 0.10, 0.15, and 0.35) mass fraction and ethylene glycol (EG) solution for (0.05, 0.10, 0.15, 0.35, 0.40 and 0.55) mass fraction. The phase equilibrium curves of different system were obtained by an isochoric pressure-search method on high pressure apparatus. The phase equilibrium regions of multicomponent gas hydrate were measured using the same composition of natural gas distributed in the South China Sea. And the different concentration solutions were prepared based formation water. The experimental data were measured in a wide range temperature from 267.74 to 298.53K and a wide range pressure from 4.22MPa to 34.72MPa. The results showed that the hydrate phase equilibrium curves shifted to the inhibition region in accordance with the increased inhibitor concentration. In addition, the equilibrium temperature would decrease about 2.7K when the concentration of MeOH increased 0.05 mass fraction. Besides, the suppression temperature was 1.25K with the 0.05 mass fraction increase of EG concentration in the range of 0.05 mass fraction to 0.15 mass fraction. While in high EG concentration region, the suppression temperature was 3.3K with the same increase of EG concentration (0.05 mass fraction).

Experimental investigation of aircraft spray cooling system with different heating surfaces and different additives

As an efficient cooling method for high heat flux, spray cooling has a great application potential on aircraft directed energy weapon cooling. Based on the analysis of previous research results, an experimental system of open loop spray cooling was established. Four different surfaces and two additives were applied and spray cooling performance including surface heat flux, surface temperature and heat transfer coefficient was experimentally investigated with water as the cooling medium. The experimental results indicate that among the four surfaces, drilling surface has the highest heat transfer coefficient and combined surface has the highest cooling efficiency. Meanwhile heat transfer can be enhanced by adding potassium chloride to a certain concentration and then deteriorated with higher concentration; heat transfer is deteriorated with the increase of ethylene glycol concentration. Therefore for aircraft spray cooling system combined surface should be applied for its advantages of low surface temperature and high cooling efficiency while ethylene glycol is preferred to improve the application range of the system in consideration of the corrosion of salt solution.

Cosolvent effect on the aggregation of amphipathic highly branched diblock polyether in aqueous solution

An amphipathic highly branched diblock polyether, PA60-2-40, was synthesized via anion ring-opening polymerization of propylene oxide (PO) and ethylene oxide (EO), using phenol-amine resin (PA) as the initiator. The molecular structure was confirmed by FT-IR and 1H NMR. The surface tension and fluorescence spectroscopy measurements provide information about the effect of cosolvents on the critical micelle concentration (CMC) and the standard Gibbs energy (ΔGomic). The cosolvents have a significant effect on the CMC of PA60-2-40; the CMC first decreases and then increases with increasing content of n-pentanol, but with an increase of ethylene glycol concentration, there is durative decrease of the CMC. The micellization becomes more spontaneous in the presence of cosolvents with more hydroxyl groups, but the CMC does not monotonically increase or decrease with the increasing carbon chain length of aliphatic monohydric alcohols. The values of surface activity parameters (Гmax, Amin and ∆Gomic) calculated all coincide with the results of the experiment. Additionally, TEM and DLS demonstrate that the size of the micelles can be changed by the addition of alcohols, but the aggregation morphology will not change.

Corrosion and self‐healing behaviour of AZ91D magnesium alloy in ethylene glycol/water solutions

AbstractCorrosion behaviour of magnesium alloy‐based engine parts in cooling system is an urgent fundamental issue in automotive field where magnesium alloys are increasingly used. In the present work, the corrosion behaviour of AZ91D magnesium alloys in various ethylene glycol/water solutions was studied by electrochemical measurements and immersion tests at room temperature. The surfaces of the samples after immersion tests were examined using scanning electron microscope (SEM) and X‐ray diffraction (XRD). The results showed that the corrosion rates of AZ91D magnesium alloys decreased with the increase of ethylene glycol concentration in ethylene glycol/water solutions and the corrosion process was dominated by pitting corrosion. A continuous protective film transferred from corrosion products was formed on the corroded surface after sufficient immersion duration in ethylene glycol/water solutions, which is able to heal the corrosion pits. The self‐healing behaviour inhibited the further corrosion of AZ91D magnesium alloy.

Influence of ethylene glycol on CaCO 3 particles formation via carbonation in the gas–slurry system

Calcium carbonate precipitation was investigated in the gas–slurry system in the reaction of calcium hydroxide and carbon dioxide. The precipitation process was occurred in the presence of ethylene glycol (EG). The used organic additive changed the viscosity of reactive mixture, the solubility of carbon dioxide and the solubility of calcium carbonate which influence CaCO 3 precipitation conditions. The course of reaction was monitored by conductivity probe. The increase concentration of ethylene glycol in the reactive mixture caused higher CO 2 usage to achieve the end point of reaction. Calcium carbonate was precipitated as calcite and produced CaCO 3 particles formed agglomerates in all experiments. The size of obtained CaCO 3 particles decreased when the EG concentration increased from 0% to 15% (by vol.). The further increase of EG concentration in solution up to 20% resulted in an increase of the size of CaCO 3 particles.

Goat and sheep ovarian tissue cryopreservation: Effects on the morphology and development of primordial follicles and density of stromal cell

The effect of exposure to cryoprotectant and cryopreservation of goat and sheep ovarian cortical fragments on the morphology of primordial follicles, stromal cell density and follicular development was performed. Goat and sheep ovarian fragments were exposed to 1.0 or 1.5 M ethylene glycol (EG) for 5, 10 or 20 min, followed or not by conventional cryopreservation. Follicular morphology and stromal cell density were evaluated by means of classical histological analysis. In addition, ovarian fragments were cultured for 1 or 7 days after cryopreservation to evaluate follicular development. Both exposure to cryoprotectant and cryopreservation of goat and sheep ovarian tissue did affect the morphology of primordial follicles and stromal cell density, except when goat ovarian tissue was exposed to EG for 5 min. Although exposure time did not influence follicular morphology in both species, increase in the exposure time from 5 to 20 min did reduce goat stromal cell density. Increase in EG concentration from 1.0 to 1.5 M did result in the decrease of the percentage of goat morphologically normal primordial follicles evaluated after exposure only. In vitro culture of frozen–thawed goat and sheep ovarian tissue showed that exposure to 1.0 M, for 10 min, before freezing of goat and sheep ovarian tissue does not impair follicular developmental capacity. In addition, stromal cell density may play a role in follicular survival and development after cryopreservation of ovarian tissue.

Effects of coolant chemistry on corrosion of 3003 aluminum alloy in automotive cooling system

AbstractIn this work, effects of coolant chemistry, including concentrations of chloride ions and ethylene glycol and addition of various ions, on corrosion of 3003 Al alloy were investigated by electrochemical impedance spectroscopy measurements and scanning electron microscopy characterization. In chloride‐free, ethylene glycol–water solution, a layer of Al‐alcohol film is proposed to form on the electrode surface. With the increase of ethylene glycol concentration, more Al‐alcohol film is formed, resulting in the increase in film resistance and charge‐transfer resistance. In the presence of Cl− ions, they would be involved in the film formation, decreasing the stability of the film. In 50% ethylene glycol–water solution, the threshold value of Cl− concentration for pitting initiation is within the range of 100 ppm to 0.01 M. When the ethylene glycol concentration increases to 70%, the threshold Cl− concentration for pitting is from 0.01 to 0.1 M. In 100% ethylene glycol, there is no pitting of 3003 Al alloy even at 0.1 M of Cl−. Even a trace amount of impurity cation could affect significantly the corrosion behavior of 3003 Al alloy in ethylene glycol–water solution. Addition of Zn2+ is capable of increasing the corrosion resistance of Al alloy electrode, while Cu2+ ions containing in the solution would enhance corrosion, especially pitting corrosion, of Al alloy. The effect of Mg2+ on Al alloy corrosion is only slight.

Pervaporation performance of chitosan–poly(acrylic acid) polyelectrolyte complex membranes for dehydration of ethylene glycol aqueous solution

Polyelectrolyte complex membranes (PECM) composed of chitosan (CS) and poly(acrylic acid) (PAAc) were prepared by blending two polymer solutions with different ratios for pervaporative dehydration of ethylene glycol (EG) aqueous solution. The composition and morphology of CS–PAAc polyelectrolyte complex membrane were characterized by Fourier transform-infrared (FT-IR) and scanning electron microscope (SEM). The mechanical properties and thermal stability of the membrane were tested by universal testing machine and thermogravimetric analysis (TGA), respectively. Effects of PAAc content, EG concentration in the feed, operating temperature and feed flow rate on pervaporation performance of the membrane were systematically investigated. Among all the concerned membranes, PECM60/40 exhibited the highest separation performance with a H 2O/EG separation factor of 105 and a flux of 216 g/m 2 h at 70 °C for 80 wt% EG aqueous solution. With the increase of operating temperature and feed flow rate, permeation flux increased but separation factor decreased. With the increase of EG concentration in feed solution, the permeation of flux of water decreased, and the flux of EG first increased and then decreased while the separation factor firstly decreased sharply but then fluctuated around 80.

Dielectric Studies of Glycine–Ethylene Glycol–Water Solutions Using Time Domain Reflectometry

Time domain reflectometry (TDR) has been used for dielectric relaxation measurements on the glycine–ethylene glycol–water ternary system (TDR) at 25, 30, 35, and 40°C in the frequency range from 10 MHz to 10 GHz. Glycine–ethylene glycol–water solutions are prepared with different concentrations of ethylene glycol (0, 5, 10, 15, 20, and 30%) and also for different glycine molar concentrations (0, 0.2, 0.4, 0.6, 0.8, and 1 M). The dielectric relaxation parameters are measured for aqueous glycine solutions also to compare the results with those for the glycine–ethylene glycol–water ternary system. For all the solutions considered, only one relaxation peak was observed in this frequency range. The complex permittivity spectra for the aqueous glycine solutions can be well described by the Cole–Davidson expression, whereas that for the ternary system can be well described by the Havriliak–Negami expression. The logarithm of the relaxation time log(τ) shows a nonlinear relation with the glycine molar concentration that implies a change in the relaxation mechanism with glycine concentration. The dielectric strength Δe increases with an increase in glycine molar concentration, whereas it decreases with an increase in ethylene glycol concentration.

ゾル‐ゲル法によるアルミナ薄膜中の空孔径制御

The alumina thin films were prepared by the sol-gel method using aluminium nitrate dissolved in 1, 3butanediol solution. The thin films usually had a homogeneous and flat surface structure. However, the surface structure of the films obtained after the immersion in an ethylene glycol and water mixed solution at 100°C changed to the sponge-like surface texture which was composed of fibrillar particle. The Al/Si intensity ratio of the thin films on a glass substrate measured by XRFS increased with the concentration of an ethylene glycol in immersion solution and reached to an approximately constant value above 22 mol%. The crystal structure of alumina after immersion changed into the amorphous from boehmite with an increase in ethylene glycol concentration. The addition of ethylene glycol has an effect upon the growth of the fibrillar particle which composes thin films. Therefore, ethylene glycol in the immersion solution restrains the peptisation of alumina particle and the production of boehmite by the hydration and enhances the growth of fibrillar particle. It was found that the vacant size in the thin films could be controlled by the ethylene glycol concentration in the immersion solution.

The Effect of Ethylene Glycol on the Thermal Denaturation of Ribonuclease A and Chymotrypsinogen A as Measured by Differential Scanning Calorimetry

Abstract The thermal denaturation of ribonuclease A(RNase A) and chymotrypsinogen A in aqueous solutions of ethylene glycol (EG) was investigated by differential scanning calorimetry at several pH values in the acidic region. The calorimetric enthalpies of denaturation, ΔHd, of these proteins increased monotonously with increasing the EG concentration under all the conditions studied. These proteins, however, differed from one another in the variation of the denaturation temperature, Td, with the addition of EG. The Td of chemotrypsinogen decreased slightly with an increase in EG concentration under all the conditions, producing a greater effect at high pH. The Td of RNase A, on the other hand, was almost independent of the EG content at pH 3.8, while at pH 2 and 3, the Td increased slightly with increasing the EG concentration and decreased slightly at pH 5. That is, EG stabilized or unstabilized these proteins against thermal denaturation, in a way which seemed to be dependent on temperature rather than the pH. The standard thermodynamic parameters for denaturation, ΔG°, ΔH°, and ΔS°, which were calculated using Td and ΔH° and assuming a constant heat capacity change, suggested that the slight increase or decrease in ΔG° induced by EG is attributed to whether ΔH° increases as much as ΔS° does or not. These results may be explained on the basis of the effect of EG on the solvation around hydrophobic groups of the protein. The EG effect may depends on the structural properties of proteins such as hydrophobicity and polarity, as well as on temperature.

Agar derivatives for chromatography, electrophoresis and gel-bound enzymes : IV. Benzylated dibromopropanol cross-linked sepharose as an amphophilic gel for hydrophobic salting-out chromatography of enzymes with special emphasis on denaturing risks

The preparation of benzylated covalently cross-linked Sepharose 2B is described. Such gel was analyzed for its degree of substitution, and gels with three different degrees of substitution were used in chromatographic experiments with dextranase, α-amylase, lactate dehydrogenase, α-chymotrypsin and trypsin. Yields and chromatographic patterns for different eluting systems were determined. It was found that gradients combining an increase in ethylene glycol concentration with a decrease in salt concentration gave better results than did pure salt gradients. No denaturation was observed for dextranase or α-amylase, but the other enzymes tested were partly denatured. The most severe denaturation was observed for lactate dehydrogenase desorbed from the highest substituted gels, although the enzyme was highly active in the adsorbed state. The results and the use of amphophilic gels are discussed.