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Author: Grafiati
Published: 18 May 2024

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1

Khokarale, Santosh Govind, Piotr Jablonski, Dariush Nikjoo, Van Minh Dinh, Ola Sundman, Knut Irgum, and Jyri-Pekka Mikkola. "Poly (Vinylidene Difluoride) Polymer in 1-Ethyl-3-methylimidazolium Acetate and Acetic Acid Containing Solvents: Tunable and Recoverable Solvent Media to Induce Crystalline Phase Transition and Porosity." Sustainable Chemistry 3, no. 4 (October 29, 2022): 455–74. http://dx.doi.org/10.3390/suschem3040028.

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In this report, 1-ethyl-3-methylimidazolium acetate, [EMIM][AcO] ionic liquid (IL) and acetic acid (AA) comprised solvents were used for the thermal treatment of poly (vinylidene difluoride), PVDF. Here, besides the various combinations of IL and AA in solvents, the pure IL and AA were also applied as a solvent upon thermal treatments. The samples obtained after the treatment were analysed for structural and crystalline phase changes, porosity, and molecular weight distribution with various analytical techniques. The Kamlet-Taft parameters measurement of the IL and AA containing solvents with different solvatochromic dyes was also performed to examine their solvent properties and correlate with the properties of the treated PVDF materials. The treatment of PVDF with pure IL results in the formation of highly carbonaceous material due to extensive dehydroflurination (DHF) as well as possibly successive cross-linking in the polymer chains. Upon IL and AA combined solvent treatment, the neat PVDF which composed of both α- and β crystalline phases was transformed to porous and β-phase rich material whereas in case of pure AA the non-porous and pure α-phase polymeric entity was obtained. A combined mixture of IL and AA resulted in a limited the DHF process and subsequent cross-linking in the polymer chains of PVDF allowed the formation of a porous material. It was observed that the porosity of the thermally treated materials was steadily decreasing with increase in the amount of AA in solvents composition and solvent with an AA:IL mole ratio of 2:1 resulted in a PVDF material with the highest porosity amongst the applied solvents. A recovery method for the IL and AA combined solvent after the thermal treatment of PVDF was also established. Hence, with varying the type of solvents in terms of composition, the highly carbonaceous materials as well as materials with different porosities as well as crystalline phases can be obtained. Most importantly here, we introduced new IL and AA containing recoverable solvents for the synthesis of porous PVDF material with the electroactive β-phase.
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2

Bhattarai, Ajaya, Kavita Pathak, and Bikash Dev. "Micellization behavior of mixed surfactants in pure water and methanol-water mixed solvent media by density methods." BIBECHANA 13 (December 3, 2015): 114–20. http://dx.doi.org/10.3126/bibechana.v13i0.13887.

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The properties of anionic-rich and cationic-rich mixtures of dodecyltrimethylammonium bromide (DTAB) and sodium dodecylsulfate (SDS) in pure water and methanol-water mixed solvent media were studied using density measurements at room temperature. The results showed that density increases with increasing concentration of surfactant mixture over the entire concentration range investigated in pure water and in the given mixed solvent media and which are found to decrease with an increase in the volume fraction of methanol in the solvent composition. The critical micelle concentration increases with the increase in volume fraction of methanol for both the anionic-rich (SDS-DTAB) and cationic-rich (DTAB-SDS) systems.BIBECHANA 13 (2016) 114-120
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3

Journal, Baghdad Science. "Study the Effect of solvent on the Optical Properties Performance of active polymeric laser media." Baghdad Science Journal 4, no. 3 (September 2, 2007): 387–92. http://dx.doi.org/10.21123/bsj.4.3.387-392.

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The paper include studies the effect of solvent of dye doped in polymeric laser sample which manufactured in primo press way, which is used as an active (R6G) tunable dye lasers. The remarks show that, when the viscosity of the solvent (from Pure Water to Ethanol), for the same concentration and thickness of the performance polymeric sample is increased, the absorption spectrum is shifts towards the long wave length (red shift), & towards short wave length (blue shift) for fluorescence spectrum, also increased the quantum fluorescence yield. The best result we obtained for the quantum fluorescence yield is (0.882) with thickness (0.25mm) in Ethanol solvent in concentration (2*10-3mole/liter), while when we used the Pure Water as a solvent, we found that the best quantum fluorescence yield is (0.72) at the same thickness & concentration of the sample.
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4

Ghigo, Giovanni, Matteo Bonomo, Achille Antenucci, Chiara Reviglio, and Stefano Dughera. "Copper-Free Halodediazoniation of Arenediazonium Tetrafluoroborates in Deep Eutectic Solvents-like Mixtures." Molecules 27, no. 6 (March 15, 2022): 1909. http://dx.doi.org/10.3390/molecules27061909.

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Deep Eutectic Solvent (DES)-like mixtures, based on glycerol and different halide organic and inorganic salts, are successfully exploited as new media in copper-free halodediazoniation of arenediazonium salts. The reactions are carried out in absence of metal-based catalysts, at room temperature and in a short time. Pure target products are obtained without the need for chromatographic separation. The solvents are fully characterized, and a computational study is presented aiming to understand the reaction mechanism.
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5

Hirotsu, Shunsuke. "Phase Transition of a Polymer Gel in Pure and Mixed Solvent Media." Journal of the Physical Society of Japan 56, no. 1 (January 15, 1987): 233–42. http://dx.doi.org/10.1143/jpsj.56.233.

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6

Minò, Antonio, Giuseppe Cinelli, Francesco Lopez, and Luigi Ambrosone. "Optical Behavior of Nile Red in Organic and Aqueous Media Environments." Applied Sciences 13, no. 1 (January 3, 2023): 638. http://dx.doi.org/10.3390/app13010638.

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A simple model is proposed to calculate the dimerization constant of a dye in non-aqueous solvents. Alkan-1ols of the formula H–(CH2)n–OH are used to study the spectroscopic behavior of Nile Red dye. The number n varied from 1 to 8 to modulate the medium hydrophobicity. Generally, Nile red is used to localize lipid droplets within cells. This molecule is non-fluorescent in water and other polar solvents but undergoes fluorescence enhancement and large absorption and emission blue shifts in non-polar environments. The calculated equilibrium constants suggest that the aggregation process is solvent-assisted. The absorption and fluorescence emission spectra reveal a marked red shift, which is studied by breaking the wavelength of the maximum band into two terms, showing the contribution of the solvent and the effect of the dye concentration. Both contributions were investigated as a function of the number n, and it was found that alkan-1ols with large n tend to aggregate and produce a smaller red shift. Conversely, it was also noticed that short-chain alkan-1ols stabilize the excited state of the dye via H-bond and the red shift increases. The hydrophilicity of the medium was found to be modulated by adding pure water, in a controlled way, to the binary systems dye–H–(CH2)n–OH (n = 1–8). The quantification of solvent hydrophilicity is described with the ratio R = water moles/alcohol moles. From this investigation, we realized that the absorption spectra values are strictly connected with the R parameter. In this context, we realized that fluorescence emission spectra allow us to determine the adjustable parameters.
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7

Hassan, Ahmed, H. A. Azab, S. A. El Gyar, and Z. A. Khafagy. "Medium effect on the second-stage dissociation constant of N-(2-acetamido)imino diacetic acid (H2ADA)." Canadian Journal of Chemistry 70, no. 6 (June 1, 1992): 1684–87. http://dx.doi.org/10.1139/v92-211.

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The second-stage dissociation constant values of N-(2-acetamido)imino diacetic acid (H2ADA) were determined at 25 ± 0.1 °C by potentiometric titration in different mixed-solvent mixtures (methanol, ethanol, dimethylformamide (DMF), dimethyl sulfoxide (DMSO), acetone, and dioxane). It was observed that the pKa value is slightly influenced as the solvent is enriched in methanol and ethanol, and remains practically constant in the presence of different amounts of DMF and DMSO. A prounounced change in the pKa value was observed as the solvent is enriched in acetone or dioxane. These results are discussed in terms of various solvent characteristics. It is concluded that the electrostatic effect has only a relatively small influence on the dissociation equilibrium of the imino group [Formula: see text]. Other solvent effects such as solvent basicity, different stabilization of the free base of the conjugate acid by hydrogen bonding interactions in aquoorganic solvent media relative to pure aqueous media, as well as proton–solvent interaction play an important role in the acid dissociation equilibrium.
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8

Su, Chien-You, Han-Liou Yi, Li-Duan Tsai, Ming-Chou Chen, and Chi-Chung Hua. "Solution properties of imidazolium-based amphiphilic polyelectrolyte in pure- and mixed-solvent media." Physical Chemistry Chemical Physics 21, no. 7 (2019): 3960–69. http://dx.doi.org/10.1039/c8cp07027j.

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9

Bhattarai, Ajaya, Sujit Kumar Shah, Ashok Kumar Yadav, and Janak Adhikari. "Effect of solvent composition on the critical micelle concentration of sodium deoxycholate in ethanol-water mixed solvent media." BIBECHANA 9 (December 10, 2012): 63–68. http://dx.doi.org/10.3126/bibechana.v9i0.7176.

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The precise measurement of the specific conductivity of sodium deoxycholate in pure water and ethanolwater mixed solvent media containing 0.10 and 0.20 volume fraction of ethanol at 303.15 K are reported. The concentration were varied from ~ 0.01 mol L-1 to ~ 0.0002 mol L-1.The conductivity of sodium deoxycholate decreases with the increase in the volume fraction of ethanol. The critical micelle concentration of sodium deoxycholate increases with the increase in the volume fraction of ethanol. DOI: http://dx.doi.org/10.3126/bibechana.v9i0.7176 BIBECHANA 9 (2013) 63-68
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10

Bhattarai, Ajaya, Sujit Kumar Shah, and Ashok Kumar Yadav. "Effect of Solvent Composition on the Critical Micelle Concentration of Cetylpyridinium Chloride in Ethanol-Water Mixed Solvent Media." Nepal Journal of Science and Technology 13, no. 1 (January 21, 2013): 89–93. http://dx.doi.org/10.3126/njst.v13i1.7446.

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The accurate measurement of the specific conductivity of cetylpyridinium chloride in pure water and ethanol-water mixed solvent media containing 0.10, 0.20, 0.30 and 0.40 volume fraction of ethanol at room temperature are reported. The concentrations were varied from ~ 0.005 mol l-1 to ~ 0.0002 mol l-1.The conductivity of cetylpyridinium chloride decreases with the increase in the volume fraction of ethanol. The critical micelle concentration of cetylpyridinium chloride increases with the increase in the volume fraction of ethanol. Nepal Journal of Science and Technology Vol. 13, No. 1 (2012) 89-93 DOI: http://dx.doi.org/10.3126/njst.v13i1.7446
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11

Journal, Baghdad Science. "Study the Effect of thickness on the Optical Properties Performance of active polymeric laser media." Baghdad Science Journal 5, no. 2 (June 1, 2008): 211–16. http://dx.doi.org/10.21123/bsj.5.2.211-216.

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The paper include study the effect thickness of the polymeric sample which is manufactured by thermo press way. The sample was used as an active tunable R6G laser media. The remarks show that, when the thickness of the samples is increased, with the same concentration, the spectrum will shift towards the short wavelength, & the quantum fluorescence yield will increased. The best result we obtained for the quantum fluorescence yield is (0.68) at the sample, with thickness (0.304mm) in Ethanol solvent, while when we used the Pure Water as a solvent, we found that the best quantum fluorescence yield is (0.63) at (0.18mm) thickness of the sample.
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12

Bhattarai, Ajaya, and Sanjay Neupane. "Effects of concentration and solvent composition on the electrical conductivity of sodium bromide in pure water and ethanol-water mixed solvent media." Kathmandu University Journal of Science, Engineering and Technology 8, no. 2 (January 3, 2013): 1–6. http://dx.doi.org/10.3126/kuset.v8i2.7318.

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Precise measurements on the conductivity of Sodium Bromide in pure water and ethanol-water mixed solvent media containing 0.10, 0.20, 0.30, 0.40, 0.50 and 0.60 volume fractions of ethanol at room temperature are reported. The concentrations were varied from ~ 0.010 to ~ 0.10 mol.L-1. The results showed a sharp increase in the conductivity with increasing electrolyte concentration. The conductivity of electrolyte decreases with increase in the amount of ethanol.Kathmandu University Journal of Science, Engineering and Technology Vol. 8, No. II, December, 2012, 1-6 DOI: http://dx.doi.org/10.3126/kuset.v8i2.7318
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13

Petukhov, Dmitrii I., Dmitrii A. Buldakov, Alexey A. Tishkin, Alexey V. Lukashin, and Andrei A. Eliseev. "Liquid permeation and chemical stability of anodic alumina membranes." Beilstein Journal of Nanotechnology 8 (March 6, 2017): 561–70. http://dx.doi.org/10.3762/bjnano.8.60.

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A study on the chemical stability of anodic alumina membranes and their performance in long-term water and organic solvent permeation experiments is reported. Anodic alumina possesses high stability for both protonic and aprotonic organic solvents. However, serious degradation of the membrane occurs in pure water, leading to a drastic decrease of permeance (over 20% of the initial value after the passing of 0.250 m3/m2 of pure water). The drying of the membrane induces further permeance drop-off. The rate of membrane degradation strongly depends on the pH of the penetrant solution and increases in basic media. According to 27Al NMR and thermogravimetry results, the degradation of the membranes is associated with the dissolution of water-soluble [Al13O4(OH)24(H2O)12]7+ polyhydroxocomplexes and their further redeposition in the form of [Al(OH)4]−, resulting in channels blocking. This process intensifies in basic pH due to the high positive charge of the anodic alumina surface. An approach for improving anodic aluminum oxide stability towards dissolution in water by carbon CVD coating of the membrane walls is suggested.
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14

Chanfreau, Sebastien, Liang-Nian He, and Bing Yu. "Electrochemical Behaviour Of Ferrocene/Ferricinium Redox System In Pure And CO2 Saturated [C6MIM][PF6]." ASEAN Journal of Chemical Engineering 11, no. 2 (February 11, 2012): 53. http://dx.doi.org/10.22146/ajche.50063.

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The electrochemical behaviour of ferrocene has been studied in green solvent combining pure ionic liquid and CO2. Experimental results were achieved for the Fc/Fc+ (ferrocene/ferricinium ion) oxidation/reduction in pure and CO2 saturated 1-hexyl-3-methylimidazolium hexafluorophosphate ([C6MIM][PF6]) over the temperature range from 298.15 K to 323.15 K. Peak shaped voltammograms were obtained and usual electrochemical parameters were calculated in order to classify electron process at the electrode. Diffusion coefficients of electroactive species were determined in the order of 10-11 m2 s-1 using the Randles–Ševcík relationship. Mass transport was also favoured by both increases in temperature and dilution of CO2 in the media.
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15

Zytner, Richard, Nihar Biswas, and Jatinder K. Bewtra. "Adsorption and desorption of perchloroethylene in soils, peat moss, and granular activated carbon." Canadian Journal of Civil Engineering 16, no. 6 (December 1, 1989): 798–806. http://dx.doi.org/10.1139/l89-123.

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Studies were conducted to evaluate the adsorption–desorption isotherms of a common dry cleaning solvent, perchloroethylene (PCE), in soils, peat moss, and granular activated carbon. The results obtained followed the Freundlich Isotherm, and the organic carbon content of the media was the most significant controlling factor in the adsorption–desorption process. The peat moss exhibited the highest residual saturation concentration for pure PCE amongst all the media tested. The desorption studies indicated that PCE had medium mobility in soil and was not significantly affected by moderate changes in pH. Key words: adsorption, desorption, Freundlich Isotherm, granular activated carbon, peat moss, perchloroethylene, soils.
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16

M. Hussein, Fawziea, Amel S. Merzah, and Zaid Waadulla Rashad. "PREPARATION OF PVC HOLLOW FIBER MEMBRANE USING (DMAC/ACETONE)." Iraqi Journal of Chemical and Petroleum Engineering 15, no. 4 (December 30, 2014): 81–87. http://dx.doi.org/10.31699/ijcpe.2014.4.8.

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Membrane manufacturing system was operated using dry/wet phase inversion process. A sample of hollow fiber membrane was prepared using (17% wt PVC) polyvinyl chloride as membrane material and N, N Dimethylacetamide (DMAC) as solvent in the first run and the second run was made using (DMAC/Acetone) of ratio 3.4 w/w. Scanning electron microscope (SEM) was used to predict the structure and dimensions of hollow fiber membranes prepared. The ultrafiltration experiments were performed using soluble polymeric solute poly ethylene glycol (PEG) of molecular weight (20000 Dalton) 800 ppm solution 25 °C temperature and 1 bar pressure. The experimental results show that pure water permeation increased from 25.7 to 32.2 (L/m2.h.bar) by adding acetone to the dope solution, while rejection decreased from 91.8 to 63.2%.
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17

Luiz, Marta, María I. Gutiérrez, Graciela Bocco, and Norman A. García. "Solvent effect on the reactivity of monosubstituted phenols towards singlet molecular oxygen (O2(1Δg)) in alkaline media." Canadian Journal of Chemistry 71, no. 8 (August 1, 1993): 1247–52. http://dx.doi.org/10.1139/v93-160.

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The influence of solvent polarity on the dye-sensitized photooxidation (singlet molecular oxygen (O2(1Δg)) mediated) of a series of para-substituted phenolates was studied. Kinetic evidence obtained shows that the overall and the pure chemical interactions, phenolate–O2(1Δg), depend on the solvent polarity in a different way. This is clearly reflected in the efficiency of O2(1Δg) photooxidation of the substrates: surprisingly, the photooxidation quantum yield increases as the overall quenching rate constant decreases. The substrate photooxidation quantum yields obtained ranged from 0.05 to 0.15, the upper limit corresponding to a moderately polar medium (a benzene–methanol mixture) and the lower to an aqueous medium. We conclude that a high solvent polarity favours only the obtainment of the encounter complex (O2(1Δg)–phenolate), whereas the reactive step is affected in much the same way as those processes where charges are neutralized along the reaction pathway. The results obtained are discussed in terms of a partly polar excited state complex between O2(1Δg) and the phenolates. The rate constant for the reactive pathway in both organic and aqueous media is correlated with the Hammet-type substituent constant R−.
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18

Mączka, Wanda, Katarzyna Wińska, Małgorzata Grabarczyk, and Barbara Żarowska. "Biotransformation of α-Acetylbutyrolactone in Rhodotorula Strains." International Journal of Molecular Sciences 19, no. 7 (July 20, 2018): 2106. http://dx.doi.org/10.3390/ijms19072106.

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Due to its structural similarity, the α’-1′-hydroxyethyl-γ-butyrolactone obtained by reduction of (±)-α-acetyl-γ-butyrolactone may have a similar function in the body to γ-butyrolactone (GBL). In the work presented, biotransformation of α-acetyl-γ-butyrolactone by three Rhodotorula strains was performed obtaining enantiomerically enriched alcohol. The process was carried out in growing and resting cultures. We studied how both media composition and organic solvent volume affected stereoselectivity and effectiveness of biotransformation. After 2 h, the enantiomerically pure (3R, 1′S)-α’-1′-hydroxyethyl-γ-butyrolactone was obtained using the R. marina AM77 strain in YPG (Yeast extract-Peptone-Glucose) medium enriched with 5% glycerol. To our best knowledge there is no previous information in the literature about the (±)-α-acetyl-γ-butyrolactone biotransformation performed in medium with addition of organic and deep eutectic solvents.
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19

Jeliński, Tomasz, Maciej Przybyłek, Magdalena Mianowana, Kinga Misiak, and Piotr Cysewski. "Deep Eutectic Solvents as Agents for Improving the Solubility of Edaravone: Experimental and Theoretical Considerations." Molecules 29, no. 6 (March 12, 2024): 1261. http://dx.doi.org/10.3390/molecules29061261.

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In this study, both practical and theoretical aspects of the solubility of edaravone (EDA) in Deep Eutectic Solvents (DESs) were considered. The solubility of edaravone in some media, including water, can be limited, which creates the need for new efficient and environmentally safe solvents. The solubility of EDA was measured spectrophotometrically and the complex intermolecular interactions within the systems were studied with the COSMO-RS framework. Of the four studied DES systems, three outperformed the most efficient classical organic solvent, namely dichloromethane, with the DES comprising choline chloride and triethylene glycol, acting as hydrogen bond donor (HBD), in a 1:2 molar proportion yielding the highest solubility of EDA. Interestingly, the addition of a specific amount of water further increased EDA solubility. Theoretical analysis revealed that in pure water or solutions with high water content, EDA stacking is responsible for self-aggregation and lower solubility. On the other hand, the presence of HBDs leads to the formation of intermolecular clusters with EDA, reducing self-aggregation. However, in the presence of a stoichiometric amount of water, a three-molecular EDA–HBD–water complex is formed, which explains why water can also act as a co-solvent. The high probability of formation of this type of complexes is related to the high affinity of the components, which exceeds all other possible complexes.
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20

Farhan, Laith Warid, Faleh H. M. Almahdawi, and Adel Sherif Hammadi. "Dissolving Precipitated Asphaltenes Inside Oil Reservoirs Using Local Solvents." Iraqi Journal of Chemical and Petroleum Engineering 21, no. 1 (March 29, 2020): 45–52. http://dx.doi.org/10.31699/ijcpe.2020.1.7.

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There are several oil reservoirs that had severe from a sudden or gradual decline in their production due to asphaltene precipitation inside these reservoirs. Asphaltene deposition inside oil reservoirs causes damage for permeability and skin factor, wettability alteration of a reservoir, greater drawdown pressure. These adverse changing lead to flow rate reduction, so the economic profit will drop. The aim of this study is using local solvents: reformate, heavy-naphtha and binary of them for dissolving precipitated asphaltene inside the oil reservoir. Three samples of the sand pack had been prepared and mixed with a certain amount of asphaltene. Permeability of these samples calculated before and after mixed with asphaltenes. Then, the permeability of samples calculated after solvents injection into that porous media. After that, all the values of samples permeability converted to average permeability damage compared with the pure samples. The results show the average permeability damage of samples that mixed with 20 gm was 24 %, but after reformate injected reduced to 14 %. After injected heavy naphtha to porous media, the average permeability reduced only to 17%. The binary solvent had been prepared from reformatted mixed with heavy naphtha gained the best results because it dropped the average permeability damage to 10%.
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21

Alatas, Fikri, Fahmi Abdul Azizsidiq, Titta Hartyana Sutarna, Hestyari Ratih, and Sundani Nurono Soewandhi. "Perbaikan Kelarutan Albendazol Melalui Pembentukan Kristal Multikomponen dengan Asam Malat." Jurnal Farmasi Galenika (Galenika Journal of Pharmacy) (e-Journal) 6, no. 1 (March 7, 2020): 114–23. http://dx.doi.org/10.22487/j24428744.2020.v6.i1.14998.

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An effort to improve the solubility of albendazole (ABZ), an anthelmintic drug has been successfully carried out through the formation of multicomponent crystal with dl-malic acid (MAL). Construction of phase solubility curve of ABZ in MAL solution and crystal morphological observations after recrystallization in the acetone-ethanol (9:1) mixture were performed for initial prediction of multicomponent crystal formation. ABZ-MAL multicomponent crystal was prepared by wet grinding or also known as solvent-drop grinding (SDG) with acetone-ethanol (9:1) mixture as a solvent followed by characterization of the multicomponent crystal formation by powder X-ray diffraction and Fourier transform infrared (FTIR) methods. The solubility of ABZ-MAL multicomponent crystal was tested in water at ambient temperature and in pH 1.2, 4.5 and 6.8 of buffered solutions at 37°C. The phase solubility curve of the ABZ in the MAL solution showed type Bs. The ABZ-MAL mixture has a different crystalline morphology than pure ABZ and MAL after recrystallization in the acetone-ethanol mixture (9:1). The powder X-ray diffraction pattern and the FTIR spectrum of ABZ-MAL from SDG different from intact ABZ and MAL powder X-ray diffraction patterns and these results can indicate the ABZ-MAL multicomponent crystal formation. The ABZ-MAL multicomponent crystal has better solubility than pure ABZ in all media used. These results can be concluded that ABZ-MAL multicomponent crystal can be prepared by solvent-drop grinding method with acetone-ethanol (9:1) mixture as a solvent and can increase the solubility of albendazole.
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Przybyłek, Maciej, Tomasz Jeliński, Magdalena Mianowana, Kinga Misiak, and Piotr Cysewski. "Exploring the Solubility Limits of Edaravone in Neat Solvents and Binary Mixtures: Experimental and Machine Learning Study." Molecules 28, no. 19 (September 29, 2023): 6877. http://dx.doi.org/10.3390/molecules28196877.

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This study explores the edaravone solubility space encompassing both neat and binary dissolution media. Efforts were made to reveal the inherent concentration limits of common pure and mixed solvents. For this purpose, the published solubility data of the title drug were scrupulously inspected and cured, which made the dataset consistent and coherent. However, the lack of some important types of solvents in the collection called for an extension of the available pool of edaravone solubility data. Hence, new measurements were performed to collect edaravone solubility values in polar non-protic and diprotic media. Such an extended set of data was used in the machine learning process for tuning the parameters of regressor models and formulating the ensemble for predicting new data. In both phases, namely the model training and ensemble formulation, close attention was paid not only to minimizing the deviation of computed values from the experimental ones but also to ensuring high predictive power and accurate solubility computations for new systems. Furthermore, the environmental friendliness characteristics determined based on the common green solvent selection criteria, were included in the analysis. Our applied protocol led to the conclusion that the solubility space defined by ordinary solvents is limited, and it is unlikely to find solvents that are better suited for edaravone dissolution than those described in this manuscript. The theoretical framework presented in this study provides a precise guideline for conducting experiments, as well as saving time and resources in the pursuit of new findings.
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Hasan, Chowdhury Md Monirul, Sheikh Aftabuddin, Miskat Sharif, and Mala Khan. "Triacylglycerol Profile of a Microalga Chlorococcum Sp. as a Potential Biofuel Feedstock." Journal of Bangladesh Academy of Sciences 40, no. 2 (December 22, 2016): 147–53. http://dx.doi.org/10.3329/jbas.v40i2.30770.

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Chlorococcum sp. has been studied as its possibility for biofuel feedstock. This alga was grown in Zarrouk media. After harvesting, lipid extraction was done by pure n-hexane and mixture of chloroform: methanol (2 : 1)) and hexane: ethanol (3 : 1). Highest oil recovery (21.20%) derived from chloroform: methanol (2 : 1) solvent system from dry biomass whereas the lowest (2.83%) came from n-hexane: ethanol solvent system from wet biomass. GC/MS used for the analysis of extracted lipid revealed that, palmitic acid methyl ester (C17H34O2), 9-octadecenoic acid methyl ester (C19H36O2) were major contents of this biofuel. The acquired fatty acid profile indicates that Chlorococcum sp. could be used as promising biofuel feedstock in near future.Journal of Bangladesh Academy of Sciences, Vol. 40, No. 2, 147-153, 2016
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24

Niraula, Tulasi Prasad, Ajaya Bhattarai, and Sujeet Kumar Chatterjee. "Critical micelle concentration of sodium dodecyl sulphate in pure water and in methanol-water mixed solvent media in presence and absence of KCl by surface tension and viscosity methods." BIBECHANA 11 (May 10, 2014): 103–12. http://dx.doi.org/10.3126/bibechana.v11i0.10388.

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Careful measurements of surface tension and viscosity of sodium dodecyl sulphate (SDS) in presence and absence of KCl in pure water and methanol-water mixed solvent media containing 0.1, 0.2, 0.3 and 0.4 volume fractions of methanol at 308.15 K are reported. The concentration of KCl is 0.01M. The concentration of SDS varies from 4.86×10-3 to 29.56×10-3 mol.l-1. The critical micelle concentration (cmc) increases with increase in percentage of methanol and decreases with addition of salt. DOI: http://dx.doi.org/10.3126/bibechana.v11i0.10388 BIBECHANA 11(1) (2014) 103-112
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GAVEAU, B., and M. MOREAU. "RESONANCE EFFECTS FOR CHEMICAL REACTIVITY IN COMPLEX MEDIA." International Journal of Bifurcation and Chaos 04, no. 05 (October 1994): 1297–309. http://dx.doi.org/10.1142/s0218127494000988.

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We study the effect of the stochastic time variations of the environment on the reaction rate constant of an elementary chemical reaction. The reaction is modelled by a one-dimensional stochastic process, which can belong to a very broad class. The short-range fluctuating interactions between the reacting complex and the solvent molecules are simulated by dichotomous barriers obeying a Poisson process, which can hinder the process. Then we relate the overall reaction constant to the reaction constant of the pure reactive process, in the absence of the barriers. We give exact results in the case of one and two barriers, and a complete analysis of the overall reaction constant, or equivalently of the overall transmission probability of the system, is presented. In particular we show that, under certain conditions, a stochastic resonance occurs, in the sense that the transmission probability can be maximized by a convenient choice of the parameters of the barriers. In this case, the fluctuating barriers increase this transmission probability with respect to its value for the purely reactive process.
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26

Wilcke, Tobias, Alexandru Postole, Marcel Krüsmann, Matthias Karg, and Thomas J. J. Müller. "Amphipolar, Amphiphilic 2,4-diarylpyrano[2,3-b]indoles as Turn-ON Luminophores in Acidic and Basic Media." Molecules 27, no. 7 (April 6, 2022): 2354. http://dx.doi.org/10.3390/molecules27072354.

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A versatile amphiphilic pyrano[2,3-b]indole for halochromic turn-ON luminescence in acidic or basic media is accessed by an insertion-coupling-cycloisomerization and adjusting solubilizing and phenolic functionalities. While almost non-emissive in neutral solutions, treatment with acids or bases like trifluoroacetic acid (TFA) or 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) reveals distinct luminescence at wavelengths of 540 nm or 630 nm in propan-2-ol, respectively. Turn-ON emission can be detected at pH values as mild as pH = 5.31 or 8.70. Quantum yields in propan-2-ol are substantial for protonated (Φf = 0.058) and deprotonated (Φf = 0.059) species. Photometrically, pKa1 of 3.5 and pKa2 of 10.5 were determined in propan-2-ol. With lipophilic polyether sidechains and hydrophilic protonation and deprotonation sites the molecule can be regarded as amphipolar, which results in good solubility properties for different organic solvents. In aqueous media, an organic co-solvent like propan-2-ol (35%) or tetrahydrofuran (25%) is needed, and the solution can be diluted with pure water without precipitation of the compound. At higher concentrations of water, a turbid solution is formed, which indicates the formation of micellar structures or clusters. With dynamic light scattering we could show that these clusters increase in size with increasing water content.
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Al Nuss, Raghad, and Hind El Zein. "Cefdinir Inclusion in Mesoporous Silica as Effective Dissolution Enhancer with Improved Physical Stability." Journal of Pharmacy and Nutrition Sciences 11 (October 21, 2021): 73–86. http://dx.doi.org/10.29169/1927-5951.2021.11.10.

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Objective: The objective of this research was to enhance the physical stability and the dissolution rate of cefdinir, a BCS class IV drug, characterized by low and variable bioavailability due to both its low solubility and low permeability. Methods: Cefdinir was loaded into the mesoporous silica (SBA-15), by using the solvent immersion method starting from different organic solvents. And then formula (F3), which exhibited the highest loading percentage, was selected to study its drug release in media with different pH (1.2, 4.5, and 6.8), and has been fully characterized by using: Fourier Transform Infrared Spectroscopy (FT-IR) Spectroscopy, Differential Scanning Calorimetry, Powder X-ray Diffraction, and has been subjected to accelerated stability tests using different temperatures and relative humidity. Drug release kinetics were studied by using the following models: Probit, Gompertz, Weibull, and Logistic. Results: The results showed a remarkable dissolution improvement of cefdinir from the loaded silica in comparison to the crystalline drug at the different studied media. Drug release behaviors were well simulated by the Weibull model for F3 in all studied media and for pure Cefdinir in phosphate buffer only, and by the Gompertz function for pure Cefdinir in HCl buffer and Acetate buffer. FTIR results showed hydrogen bonds formed between the drug and silica, DSC and PXRD results revealed the transformation of cefdinir into an amorphous form upon adsorption. Stability studies under different conditions revealed the ability of mesoporous silica to maintain the amorphous state of the drug, which has been formed upon adsorption, and to prevent re-organization in the crystal nucleus of the drug molecules. Conclusion: Thus, loading cefdinir onto mesoporous silica can be used as a promising method to enhance drug dissolution, and maintain the physical stability of its amorphous form.
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28

Boulafrouh, Lamia, Stéphanie Boudesocque, Aminou Mohamadou, and Laurent Dupont. "Separation of Co(II) and Ni(II) Using an Analog of Glycine-Betaine Based on Task-Specific Ionic Liquids." Separations 10, no. 5 (May 11, 2023): 305. http://dx.doi.org/10.3390/separations10050305.

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A series of salts based on ethyl ester glycine-betaine derivatives, viz tri(n-pentyl)[2-ethoxy-2-oxoethyl]ammonium bromide, have been synthesized. These cations generate hydrophobic ionic liquids (ILs) with bis(trifluoromethylsulfonyl)imide (Tf2N−) or dicyanamide (Dca−) anions. These new analogues of glycine-betaine-based ionic liquids (AGB-ILs) were characterized using spectroscopic methods (IR, 1H, and 13C NMR) and elemental analysis. These AGB-ILs were used for the selective separation of Ni(II) and Co(II) in saline media using pure ILs phase or ILs diluted in organic solvent. Interestingly, extraction of Co(II) and Ni(II) in Dca-based AGB-ILs can be enhanced using salts with chaotropic anions such as NaNO3 (E > 90% for Co(II) and E = 85% for Ni(II)). Tf2N−-based ionic liquids do not extract Ni(II) or Co(II) even in NaCl 4M. Dca−-based ILs lead to a quasi-quantitative extraction of Co(II), while extraction of Ni(II) is limited to a few percent (17%) leading to separation factors higher than 100, ensuring a good separation of both metals. Cobalt could be back-extracted from the ionic liquid phase with water or with an aqueous solution of Na2SO4, which limits the release of the AGB cation in aqueous media, thus preserving its integrity. Results obtained by AGB-ILs diluted in organic solvent were comparable to those obtained with the pure AGB-ILs phase, indicating that this strategy can be deployed on systems working continuously out of equilibrium since the extraction mechanisms involve fast equilibria.
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29

Chen, Ying, Nana Xia, Yuewang Liu, and Pu Wang. "Efficient Biocatalytic Preparation of Optically Pure (R)-1-[4-(Trifluoromethyl)phenyl]ethanol by Recombinant Whole-Cell-Mediated Reduction." Catalysts 9, no. 4 (April 25, 2019): 391. http://dx.doi.org/10.3390/catal9040391.

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(R)-1-[4-(Trifluoromethyl)phenyl]ethanol is an important pharmaceutical intermediate of a chemokine CCR5 antagonist. In the present study, a bioprocess for the asymmetric reduction of 4-(trifluoromethyl)acetophenone to (R)-1-[4-(trifluoromethyl)phenyl]ethanol was developed by recombinant Escherichia coli cells with excellent enantioselectivity. In order to overcome the conversion limitation performed in the conventional buffer medium resulting from poor solubility of non-natural substrate, we subsequently established a polar organic solvent-aqueous medium to improve the efficacy. Isopropanol was selected as the most suitable cosolvent candidate, based on the investigation on a substrate solubility test and cell membrane permeability assay in different organic solvent-buffer media. Under the optimum conditions, the preparative-scale asymmetric reduction generated a 99.1% yield with >99.9% product enantiomeric excess (ee) in a 15% (v/v) isopropanol proportion, at 100 mM of 4-(trifluoromethyl)acetophenone within 3 h. Compared to bioconversion in the buffer medium, the developed isopropanol-aqueous system enhanced the substrate concentration by 2-fold with a remarkably improved yield (from 62.5% to 99.1%), and shortened the reaction time by 21 h. Our study gave the first example for a highly enantioselective production of (R)-1-[4-(trifluoromethyl)phenyl]ethanol by a biological method, and the bioreduction of 4-(trifluoromethyl)acetophenone in a polar organic solvent-aqueous system was more efficient than that in the buffer solution only. This process is also scalable and has potential in application.
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30

Nazeer, Muhammad Anwaar, Emel Yilgor, Mustafa Baris Yagci, Ugur Unal, and Iskender Yilgor. "Effect of reaction solvent on hydroxyapatite synthesis in sol–gel process." Royal Society Open Science 4, no. 12 (December 2017): 171098. http://dx.doi.org/10.1098/rsos.171098.

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Synthesis of hydroxyapatite (HA) through sol–gel process in different solvent systems is reported. Calcium nitrate tetrahydrate (CNTH) and diammonium hydrogen phosphate (DAHP) were used as calcium and phosphorus precursors, respectively. Three different synthesis reactions were carried out by changing the solvent media, while keeping all other process parameters constant. A measure of 0.5 M aqueous DAHP solution was used in all reactions while CNTH was dissolved in distilled water, tetrahydrofuran (THF) and N , N -dimethylformamide (DMF) at a concentration of 0.5 M. Ammonia solution (28–30%) was used to maintain the pH of the reaction mixtures in the 10–12 range. All reactions were carried out at 40 ± 2°C for 4 h. Upon completion of the reactions, products were filtered, washed and calcined at 500°C for 2 h. It was clearly demonstrated through various techniques that the dielectric constant and polarity of the solvent mixture strongly influence the chemical structure and morphological properties of calcium phosphate synthesized. Water-based reaction medium, with highest dielectric constant, mainly produced β-calcium pyrophosphate (β-CPF) with a minor amount of HA. DMF/water system yielded HA as the major phase with a very minor amount of β-CPF. THF/water solvent system with the lowest dielectric constant resulted in the formation of pure HA.
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31

Howlader, Md Sariful Islam, Jayanta Kishor Chakrabarty, Khandokar Sadique Faisal, Uttom Kumar, Md Raihan Sarkar, and Mohammad Firuz Khan. "Enhancing dissolution profile of diazepam using hydrophilic polymers by solid dispersion technique." International Current Pharmaceutical Journal 1, no. 12 (November 1, 2012): 423–30. http://dx.doi.org/10.3329/icpj.v1i12.12453.

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The aim of the present study was to improve the solubility and dissolution rate of a poorly water-soluble drug by a solid dispersion technique, in order to investigate the effect of these polymers on release mechanism from solid dispersions. Diazepam was used as a model drug to evaluate its release characteristics from different matrices. Solid dispersions were prepared by using polyethylene glycol 6000 (PEG-6000), HPMC, HPC and Poloxamer in different drug-to-carrier ratios (1:2, 1:4, 1:6, 1:8, 1:10). The solid dispersions were prepared by solvent method. The pure drug and solid dispersions were characterized by in vitro dissolution study. Distilled water was used as dissolution media, 1000 ml of distilled water was used as dissolution medium in each dissolution basket at a temperature of 37°C and a paddle speed of 100 rpm. The very slow dissolution rate was observed for pure Diazepam and the dispersion of the drug in the polymers considerably enhanced the dissolution rate. This can be attributed to improved wettability and dispersibility, as well as decrease of the crystalline and increase of the amorphous fraction of the drug. SEM (Scanning Electron microscope) studies shows that the solid dispersion having a uniform dispersion. Solid dispersions prepared with PEG-6000, Poloxamer showed the highest improvement in wettability and dissolution rate of Diazepam. Solid dispersion containing polymer prepared with solvent method showed significant improvement in the release profile as compared to pure drug, Diazepam.DOI: http://dx.doi.org/10.3329/icpj.v1i12.12453 International Current Pharmaceutical Journal 2012, 1(12): 423-430
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32

Mączka, Wanda, Katarzyna Wińska, Małgorzata Grabarczyk, and Barbara Żarowska. "Yeast-Mediated Stereoselective Reduction of α-Acetylbutyrolactone." Applied Sciences 8, no. 8 (August 9, 2018): 1334. http://dx.doi.org/10.3390/app8081334.

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α’-1’-Hydroxyethyl-γ-butyrolactone—a product of reduction of α-acetylbutyrolactone possesses two stereogenic centres and two reactive functionalities (an alcohol and an ester group). Additionally, this compound has a similar structure to γ-butyrolactone (GBL) which is psychoactive. In the present work, biotransformation using seven yeast strains was used to obtain anti stereoisomers of α’-1’-hydroxyethyl-γ-butyrolactone. The process was carried out in both growing and resting culture. The effect of media composition and organic solvent addition on stereoselectivity and effectiveness of biotransformation was also studied. After one day of transformation, optically pure (3R,1’R)-hydroxylactone was obtained by means of Yarrowia lipolytica P26A in YPG medium (yeast extract (1%), peptone (2%) and glucose (2%)). In turn, the use of resting cells culture of Candida viswanathi AM120 in the presence of 10% DES (deep eutectic solvent) allowed us to obtain a (3S,1’S)-enantiomer with de = 85% (diastereomeric excess) and ee 76% (enantiomeric excess).
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33

Elfita, Elfita, Muharni Muharni, Munawar Munawar, and Septa Aryani. "SECONDARY METABOLITE FROM ENDOPHYTIC FUNGI Aspergillus niger OF THE STEM BARK OF KANDIS GAJAH (Garcinia griffithii)." Indonesian Journal of Chemistry 12, no. 2 (June 4, 2012): 195–200. http://dx.doi.org/10.22146/ijc.21363.

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Garcinia griffithii are known as kandis gajah including the Garcinia genus. This plant has been traditionally used by local communities Sarasah Bonta, Lembah Arau, West Sumatra, to treat various diseases including gout. Aspergillus niger was isolated from the tissues of the stem bark of Garcinia griffithii. The fungi strain was identified base on colony and cell morphology characteristic. Aspergillus niger cultured in media 5L Potatos Dextose Broth (PDB) for 8 weeks and filtered. Media that already contains secondary metabolites are partitioned using ethyl acetate solvent in 5 L (twice), followed by evaporation. Furthermore, the extract is separated by chromatographic techniques to obtain a pure compound of white crystal. The molecular structures of isolated compounds are determined by spectroscopic methods including IR, 1H-NMR, 13C-NMR, HMQC, HMBC, and COSY. The compound was determined as phenolic (1).
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34

Li, Xianxue. "Solvothermal synthesis and characterization of well-dispersed cerium-doped Y2SiO5 phosphor particles." International Journal of Materials Research 112, no. 10 (October 1, 2021): 812–16. http://dx.doi.org/10.1515/ijmr-2021-8281.

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Abstract Well-dispersed cerium-doped Y2SiO5 (Ce:YSO) phosphor particles with spherical morphology and good luminescence intensity have been achieved by a solvothermal method with ethanol and water as solvent media. X-ray diffraction, Fourier transform infrared spectroscopy, fluorescence spectrophotometry and transmission electron microscopy were employed to characterize the as-synthesized Ce:YSO precursor and powders. The results showed that pure-phase Ce:YSO powders with a mean particle size of about 162 nm were accurately available at 310°C and above. The fluorescence ability and persistent luminescence decay properties of the Ce:YSO powders were also studied, and the excellent fluorescence properties could be attributed to the homogeneous Ce:YSO particles obtained through the solvothermal method.
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35

Barros, Marisa C. F., Ana C. F. Ribeiro, and Cecília I. A. V. Santos. "An Assessment of the Chemical Compatibility of Viton Fluoropolymers and Some Harsh Organic Liquid Mixtures." Processes 11, no. 7 (July 13, 2023): 2088. http://dx.doi.org/10.3390/pr11072088.

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The molecular transport of a series of industrial solvent mixtures into O-rings of Viton fluoropolymers was studied. Sorption, diffusion, and permeation of the individual liquids toluene, cyclohexane, and methanol, and their binary and ternary mixtures, were evaluated from the solvent uptake using a gravimetric method. From the sorption results, the diffusion coefficients were calculated using Fick’s equation. A numerical method was employed to calculate the liquid concentration profiles in cylinder-shaped polymers. The desorption mechanism was also evaluated. The composition dependence of sorption, diffusion, and permeation was assessed, and the results were analysed in terms of potential interactions between polymer and penetrant molecules. Observed sorption of methanol and methanol mixtures by the polymer was very high, in some cases higher than for pure liquids. In general, the amount of methanol present in the mixture determined its diffusion coefficient. Methanol showed the smallest solubility coefficient within the polymer, but due to its high mobility and permeability, it was shown to be the liquid that flows faster through Viton fluoropolymers. Flows of toluene and cyclohexane are still considerable, notwithstanding that this fluoropolymer is usually indicated as hydrocarbon resistant. This is an important fact to keep in mind when choosing sealings for applications with a mix of solvent media.
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36

Yu, Hou Lin, Wenliang Shi, Shuaishuai Li, Junma Zhang, Xiaobo Zhang, Huaping Wu, Tingyu Zhao, and Aiping Liu. "Solvent-mediated crystalline phases of NixSy anchored on rGO sheets as electrocatalysts for hydrogen evolution application." Functional Materials Letters 12, no. 01 (January 21, 2019): 1850089. http://dx.doi.org/10.1142/s1793604718500893.

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A facile, one-pot solvent-mediated hydrothermal process was adopted to prepare nickel sulfide nanoparticles decorated on reduced graphene oxide (NixSy/rGO) as electrocatalysts for hydrogen evolution reaction (HER). The designed solvent (ethylene glycol and deionized water) played a decisive role in controlling both crystalline phase and morphology of NixSy/rGO composites, leading to pure [Formula: see text]-NiS nanoparticles uniformly distributed on rGO sheets under suitable volume ratio of ethylene glycol and deionized water (2:1). The optimized [Formula: see text]-NiS/rGO showed prominent HER catalytic performance with a rather small Tafel slope of 93[Formula: see text]mV/decade and prominent current density of 10[Formula: see text]mA/cm2 at the overpotential of 177[Formula: see text]mV in alkaline environments when compared to pristine [Formula: see text]-NiS and NiS2/rGO catalysts. The excellent catalytic performance and long-term durability even after 8000 cycles confirmed the potential of [Formula: see text]-NiS/rGO composites as efficient electrocatalysts for HER in the alkaline media.
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37

A. R. Rassoul, G., and Ali A. A. Hadi. "Drag Reduction of Crude Oil Flow in Pipelines Using Sodium Dodecyl Benzene Sulfonate Surfactant." Iraqi Journal of Chemical and Petroleum Engineering 8, no. 2 (June 30, 2007): 29–34. http://dx.doi.org/10.31699/ijcpe.2007.2.5.

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In the present work, a closed loop circulation system consist of three testing sections was designed and constructed. The testing sections made from (3m) of commercial carbon steel pipe of diameters(5.08, 2.54 and 1.91 cm) . Anionic surfactant (SDBS )with concentrations of (50, 100, 150, 200 and 250 ppm) was tested as a drag reducing agent. The additive(SDBS)studied using crude oil from south of Iraq. The flow rates of crude oil were used in 5.08 and 2.54 cm I.D. pipes are (1 - 12) m3/hr while (1-6) m3/hr were used in 1.91 cm J .D. pipe . Percentage drag reduction (%Dr) was found to increase by increasing solution velocity, pipe diameter and additives concentration (i.e. increasing Renolds number). Also it was found that there is no change in apparent physical properties (viscosity) of crude oil after the addition of SDBS. The higher value of drag reduction of 54% in 5.08 cm I.D. was observed using 250 ppm SDBS surfactant dissolved in the used crude oil at flow rate of 12 m3/hr. Friction factor was calculated from experimental data. The friction factors values for pure solvent lies near or at Blasius asymptote suggested for flow of Newtonian fluids. After the addition of small amount of SDBS, the friction factor values were positioned below Blasius asymptote toward Virk maximum drag reduction asymptote, which was never reached.
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38

Vedernikova, Anna A., Mikhail D. Miruschenko, Irina A. Arefina, Anton A. Babaev, Evgeniia A. Stepanidenko, Sergei A. Cherevkov, Igor G. Spiridonov, et al. "Dual-Purpose Sensing Nanoprobe Based on Carbon Dots from o-Phenylenediamine: pH and Solvent Polarity Measurement." Nanomaterials 12, no. 19 (September 23, 2022): 3314. http://dx.doi.org/10.3390/nano12193314.

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Today, the development of nanomaterials with sensing properties attracts much scientific interest because of the demand for low-cost nontoxic colloidal nanoprobes with high sensitivity and selectivity for various biomedical and environment-related applications. Carbon dots (CDs) are promising candidates for these applications as they demonstrate unique optical properties with intense emissions, biocompatibility, and ease of fabrication. Herein, we developed synthesis protocols to obtain CDs based on o-phenylenediamine with a variety of optical responses depending on additional precursors and changes in the reaction media. The obtained CDs are N-doped (N,S-doped in case of thiourea addition) less than 10 nm spherical particles with emissions observed in the 300–600 nm spectral region depending on their chemical composition. These CDs may act simultaneously as absorptive/fluorescent sensing probes for solvent polarity with ∆S/∆ENT up to 85, for ∆ENT from 0.099 to 1.0 and for pH values in the range of 3.0–8.0, thus opening an opportunity to check the pH in non-pure water or a mixture of solvents. Moreover, CDs preserve their optical properties when embedded in cellulose strips that can be used as sensing probes for fast and easy pH checks. We believe that the resulting dual-purpose sensing nano probes based on CDs will have high demand in various sensing applications.
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39

Rajab, Nawal Ayash. "PREPARATION AND IN VITRO EVALUATION OF LACIDIPINE ORAL LIQUID SOLID TABLET AS AN APPROACH OF SOLUBILITY AND DISSOLUTION RATE ENHANCEMENT." International Journal of Applied Pharmaceutics 10, no. 1 (January 6, 2018): 145. http://dx.doi.org/10.22159/ijap.2018v10i1.22313.

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Objective: The aim of the present study was to prepare a new liquid-solid tablet to enhance the dissolution and bioavailability of a poor water soluble calcium channel blocker lacidipine.Methods: Firstly, solubility study of lacidipine in different media of water-miscible non-volatile solvents as tween 20, tween 80, propylene glycol, liquid paraffin, PEG200, PEG400, and PEG600 was investigated to select the most suitable solvent. A mathematical model was applied to calculate the appropriate amount of carrier and coating material.Four liquid-solid tablets of 6 mg lacidipine were prepared by dissolving the drug in the previously chosen water miscible non-volatile solvents, then a binary mixture of the carrier (Avicel PH 102) and coating material (Aerosil 200) at a ratio of 45:1 was used in all preparation since it gave the optimal flow property. Croscarmellose and magnesium stearate were incorporated in all prepared formulas as super disintegrant and lubricant respectively. On the other hand, directly compressed lacidipine tablet of the same previous composition without the addition of any non-volatile solvent was prepared for comparism study. Both characterizations of powder mixture and post-compression tablet evaluations were done. Differential scanning calorimetry (DSC) and fourier transform infrared spectroscopy (FTIR) were investigated for the pure drug, physical mixture, and selected liquid-solid tablet to exclude any drug-excipients interaction.Results: The obtained results indicated that PEG 200 was the most suitable solvent with lacidipine solubility of 2.81 mg/ml. Flowability of all the prepared formulas was found to be within the specification limits. The liquid-solid tablet formula with PEG 200 at 10% w/w lacidipine was the most suitable one in the term of disintegration time (21±0.2 second), 100% of drug release within 10 min, and with accepted other tablet properties.DSC thermograms for both physical mixture of selected liquisolid system and its tablets illustrated the formation of lacidipine amorphous solid solution. The absence of chemical interaction between drug and other formula components was confirmed by remaining all characteristic peaks of lacidipine in all investigated FTIR spectra.Conclusion: Liquid-solid tablet was considered as a promising system to enhance solubility and dissolution rate of poor-water soluble lacidipine.
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40

Harifi-Mood, Ali Reza, and Aazam Jafarinejad. "Solvent Polarity, Hydrogen-Bonding and Solvophobicity Effects on the Nucleophilic Substitution of Benzenesulfonyl Chloride with Aniline in Aqueous and Non-Aqueous Solutions of Methanol." Progress in Reaction Kinetics and Mechanism 36, no. 4 (November 2011): 361–70. http://dx.doi.org/10.3184/146867811x13103063831450.

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The reaction between benzensulfonyl chloride and aniline was studied in various compositions of methanol with ethyl acetate, propan-2-ol and water at 25° C. Second-order rate coefficients of this reaction were determined; those in pure solvents were in the order of water > methanol >propan-2-ol> ethyl acetate. Rates decreased sharply with the mole fraction of ethyl acetate in methanol- ethyl acetate mixtures and showed an increasing trend with water content in methanol-water mixtures. Linear free energy relationship regressions showed that the polarity, hydrogen-bond donor ability and hydrophobicity of the media were the main factors affecting the reaction rate coefficient.
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41

Biswas, Shanta, Taslim U. Rashid, Abul K. Mallik, Md Minhajul Islam, M. Nuruzzaman Khan, Papia Haque, Mala Khan, and Mohammed Mizanur Rahman. "Facile Preparation of Biocomposite from Prawn Shell Derived Chitosan and Kaolinite-Rich Locally Available Clay." International Journal of Polymer Science 2017 (2017): 1–8. http://dx.doi.org/10.1155/2017/6472131.

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A novel composite material was prepared from prawn shell derived chitosan (CHT) and locally available kaolinite-rich modified Bijoypur clay (MC) using a facile technique in which dilute acetic acid was used as a solvent for dissolving chitosan and composite fabrication whereas distilled water was used for preparing the clay dispersion. Bijoypur clay mainly consists of kaolinite clay mineral and it was modified with the dodecyl amine to make it organophilic. Morphology and properties of the composites (different weight ratio of MC and CHT) have been studied and compared with those of pure CHT and MC. Purification and modification of Bijoypur clay were investigated by X-ray diffraction (XRD), X-ray fluorescence (XRF), and Fourier transformed infrared spectroscopy (FTIR) analyses. The fabrication of CHT-MC composites was confirmed by FTIR analysis. Thermogravimetric analysis (TGA) and differential scanning colorimetry (DSC) were used to investigate the thermal stability of the composites. It was observed that dispersed clay improves the thermal stability and enhances the hardness of the matrix systematically with the increase of clay loading. In this study, a better insolubility in both acidic and alkaline media of the composites is also observed compared to pure chitosan.
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42

Ramamurthy. "Achiral Zeolites as Reaction Media for Chiral Photochemistry." Molecules 24, no. 19 (October 2, 2019): 3570. http://dx.doi.org/10.3390/molecules24193570.

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Obtaining enantiomerically-enriched photoproducts from achiral reactants has been a long-sought goal. The various methods developed to achieve chiral induction in photoproducts during the last fifty years still suffer from a lack of predictability, generality, and simplicity. With the current emphasis on green chemistry, obtaining enantiomerically enriched products via photochemistry is a likely viable alternative for the future. Of the various approaches developed during the last three decades, the one pioneered in the author’s laboratory involved the use of commercially-available and inexpensive achiral zeolites as the media. This approach does not use any solvent for the reaction. Examples from these studies are highlighted in this article. Since no chiral zeolites were available, when the work was initiated in the author’s laboratory, commercially-available zeolites X and Y were modified with chiral inductors so that the reaction space becomes chiral. The results obtained established the value of chirally-modified, commercial zeolites as media for achieving chiral induction in photochemical reactions. A recent report of the synthesis of a chiral zeolite is likely to stimulate zeolite-based chiral photochemistry in synthesizing enantiomerically-pure organic molecules. The availability of chiral zeolites in future is likely to energize research in this area. Our earlier observations on this topic, we believe, would be valuable for progress of the field. Keeping this in mind, I have summarized the work carried out in our laboratory on chiral photochemistry on chirally-modified zeolites. This review does not include examples where high chiral induction has been obtained via a strategy that examines molecules appended with chiral auxiliary within achiral and chirally-modified zeolites. The latter approach yields products with diastereomeric excess >80%.
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43

Kiliç, Hasan, and Er Birol. "Potentiometric investigation of acid-base equilibria of two new pyrimidine derivatives in various methanol-water media." Journal of the Serbian Chemical Society 71, no. 1 (2006): 43–54. http://dx.doi.org/10.2298/jsc0601043k.

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The acid-base properties of 1-amino-5-benzoyl-4-phenyl-1H-pyrimidine-2-one (L1) and 1-amino-5-benzoyl-4-phenyl-1H-pyrimidine-2-thione (L2) were investigated potentiometrically at an ionic strength of 0.10M(LiCl) in 19.8, 33.6 and 55.9 % (v/v) methanol-water mixtures at 25.0 ? 0.1 ?C. The apparent dissociation constants (psKa) were calculated for the di-protonated form (L1H2+2 and L2H2+2) of pyrimidine bases, using a software package TITFIT, which were then extrapolated to pure water to derive the dissociation constants in aqueous solution (pKa). The aqueous pKa constants were found to be: L1, pKa1 = 3.76 and pKa2 = 6.95; L2, pKa1 = 3.57 and pKa1 = 6.90. At pH <- 2.00, the dominant species in solution were the protonated form of the amino group substituted at the 1-position, while at a pH around 5.00, they were the protonated form of the pyrimidine ring nitrogen at the 3-position. An effect of intramolecular hydrogen bonding on the psKa values was observed with L1 but not L2. The effects of molecular structure and solvent medium on the psKa values are also discussed.
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44

Vimalson, D. Christopher, S. Parimalakrishnan, N. S. Jeganathan, and S. Anbazhagan. "SOLID DISPERSION TECHNIQUE TO ENHANCE THE SOLUBILITY AND DISSOLUTION OF FEBUXOSTAT AN BCS CLASS II DRUG." International Journal of Applied Pharmaceutics 11, no. 1 (January 9, 2019): 241. http://dx.doi.org/10.22159/ijap.2019v11i1.30539.

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Objective: The present study was aimed to enhance the solubility of poorly water-soluble drug (BCS Class II) Febuxostat using water-soluble polymers.Methods: Pre-formulation studies like drug excipient compatibility studies by Fourier-transform infrared spectroscopyDifferential scanning calorimetry and determination of saturation solubility of drug individually in various media like distilled water and pH 7.4 phosphate buffer. Solid dispersions of Febuxostat was prepared using Polyethylene glycol (PEG 6000) (fusion method) and Polyvinyl pyrrolidone (PVP K30) (solvent evaporation method) in various ratios like 1:1, 1:2, 1:3 and 1:4 separately. The formulated solid dispersions were evaluated for percentage yield, drug content and in vitro dissolution studies.Results: From the results of pre-formulation studies it was revealed that there was no interaction between drug and excipients and the pure drug was poorly soluble in water. The percentage yield of all formulations was in the range of 54-78 %, and drug content was in the range of 43-78 mg. The solid dispersion containing polyvinylpyrrolidone K 30 in 1:4 ratio showed the highest amount of drug release at the end of 30 min than other formulations.Conclusion: Finally it was concluded that solid dispersion prepared with PVP K-30 in 1:4 ratio by solvent evaporation method was more soluble than by fusion method.
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45

Elfita, Elfita, Muharni Muharni, Munawar Munawar, Salni Salni, and Ade Oktasari. "Senyawa Antimalaria dari Jamur Endofitik Tumbuhan Sambiloto (Andographis paniculata Nees)." Jurnal Natur Indonesia 13, no. 2 (November 21, 2012): 123. http://dx.doi.org/10.31258/jnat.13.2.123-129.

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Plants have been the chief source of compounds of medicine for thousand of years. Plants are also the source ofmany medicines for the majority of the world’s population. The role of biotechnology is very important for multiplying,conserving the spesies, and enhancing the production of secondary metabolites. Endophytic are microbes thatinhabit plants are currently considered to be a wellspring of novel secondary metabolites offering the potensial formedical and industrial exploitation. Plants with ethnobotanical history, for example sambiloto (Andographispaniculata Nees) are likely candidates for finding bioactive compounds. Isolation begin with cultivation of Aspergillusflavus fungi in 2 liter of Potato Dextrose Broth media for four weeks. Media is extracted into the solvent n-hexaneand ethylacetate following by evaporation. Ethylacetate extracts were separated by chromatography techniquesin order to get pure compound in the form of white crystal. Phytochemical tests showed that the isolated compoundis alkaloid. The molecular structure of the isolated compound was determined based on spectroscopic data,including UV, IR, 1H-NMR, 13C-NMR, HMQC, and HMBC spectrum. The compound was determined as7-hydroxypiranopiridin-4-on with molecule formula C8H7NO2 (Mr=149). The compound has antimalarial activityagainst Plasmodium falciparum 3D7, with IC50 values 0,201 μM.
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46

Angar, Nour-Elhouda, and Djamel Aliouche. "Deswelling of Hydrogels in Aqueous and Polyethylene Glycol Solutions. A New Approach for Drug Delivery Application." Periodica Polytechnica Chemical Engineering 62, no. 2 (November 23, 2017): 137. http://dx.doi.org/10.3311/ppch.11132.

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To enhance the properties of pure poly(acrylamide) hydrogel, diprotic maleic acid co-monomer was included into the reaction mixture during hydrogel synthesis. These hydrogels have been shown important swelling in distilled water and deswelling in acidic solution. In present work, we based on these considerations to study the deswelling behaviour of poly(acrylamide-co-maleic acid) hydrogels in different media (air, polyethylene glycol 200 (PEG200), acidic solution). Hydrogels of poly(acrylamide) and its copolymers with maleic acid were prepared by copolymerization and chemical crosslinking with methylene bisacrylamide. The obtained hydrogels have shown substantial mass swelling in distilled water and shrinking in acidic solution and PEG200. Results showed that the PEG200 was a better solvent for hydrogel deswelling and possibly will be used for gel drying. The swelling and deswelling kinetics were described by second-ordered and first-ordered models, respectively. BSA desorption in PEG200 was also studied.
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47

Punjungsari, Tyas Nyonita. "CHARACTERIZATION OF SULFATE REDUCING BACTERIA FROM BIOFILM SULFATE REDUCTION AND CU PRECIPITATION BIOREACTOR (BATCH CULTURE)." JARES (Journal of Academic Research and Sciences) 2, no. 2 (May 4, 2018): 1. http://dx.doi.org/10.35457/jares.v2i2.400.

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The biofilm is a microbial community structure formed on the zeolite surface in a sulfate reduction bioreactor and Cu deposition using a SRB consortium . The biofilm soluble microbial solvent is expected to have the capability in sulfate reduction and Cu deposition. Characterization of isolates is required for the optimization of pure culture . The aim of this study is to isolate and characterize the biofilm sulfate reducing bacteria in the sulfate reduction bioreactor and the precipitation of Cu in Batch Culture by a consortium of Sulfate Reducing Bacteria. The method used in this study cultivation was done by using postgate B medium, isolation was done by diluting biofilm on NaCl salt, bacteria grown on NB and postgate B media, characterization done by morphology and biochemistry. There were 3 isolates of B1 (Metylobacterium ), B3 ( Desulfucoccus ), and B2 ( Desulfobacter ). B3 ( Desulfococcus) has the best ability to reduce sulfate and Cu precipitation.Keywords : Sulfur Reducing Bacteria (SRB), Biofilm, Sulfate, Cu. Received: 26 August, 2017; Accepter: 10 September, 2017
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48

Punjungsari, Tyas Nyonita. "CHARACTERIZATION OF SULFATE REDUCING BACTERIA FROM BIOFILM SULFATE REDUCTION AND CU PRECIPITATION BIOREACTOR (BATCH CULTURE)." Journal of Academic Research and Sciences (JARES) 2, no. 2 (May 4, 2018): 1. http://dx.doi.org/10.30957/jares.v2i2.400.

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The biofilm is a microbial community structure formed on the zeolite surface in a sulfate reduction bioreactor and Cu deposition using a SRB consortium . The biofilm soluble microbial solvent is expected to have the capability in sulfate reduction and Cu deposition. Characterization of isolates is required for the optimization of pure culture . The aim of this study is to isolate and characterize the biofilm sulfate reducing bacteria in the sulfate reduction bioreactor and the precipitation of Cu in Batch Culture by a consortium of Sulfate Reducing Bacteria. The method used in this study cultivation was done by using postgate B medium, isolation was done by diluting biofilm on NaCl salt, bacteria grown on NB and postgate B media, characterization done by morphology and biochemistry. There were 3 isolates of B1 (Metylobacterium ), B3 ( Desulfucoccus ), and B2 ( Desulfobacter ). B3 ( Desulfococcus) has the best ability to reduce sulfate and Cu precipitation.Keywords : Sulfur Reducing Bacteria (SRB), Biofilm, Sulfate, Cu. Received: 26 August, 2017; Accepter: 10 September, 2017
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49

Montes-Albino, Gina, Marco Gálvez-Saldaña, Boris Renteria-Beleño, and Oscar Perales-Pérez. "Effect of the Type of Solvent and Bi-Stoichiometric Excess on the Purity of Nanocrystalline Bismuth Ferrite Single Phase." MRS Proceedings 1454 (2012): 45–50. http://dx.doi.org/10.1557/opl.2012.1232.

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ABSTRACTThe main challenge associated with the synthesis of pure bismuth ferrite (BFO) is the extremely high stability of parasitic or secondary phase Bi-oxides, which contaminates the single ferrite phase and affects the corresponding functional properties. Therefore, any attempt to determine the optimum synthesis conditions conducive to the inhibition of the formation of those impurity phases becomes indispensable. Accordingly, the present work addresses the systematic evaluation of the type of solvent and synthesis parameters to exclusively produce the BFO structure. Nanocrystalline BFO powders were synthesized after thermal treatment of the solid intermediates formed in ethylene glycol and acetic acid media. The experimental work also considered the effect of the excess of Bi species with respect to the BiFeO3stoichiometry and the annealing of the intermediates at different temperatures. The structure formation was confirmed by XRD analysis and magnetic properties were studied by VSM. X-ray diffraction analyses confirmed that powders exhibiting single phase BFO structure were produced after annealing the intermediate which was formed in acetic acid for one hour at 700°C. The average crystallite size and lattice parameter were calculated to be approximately 40 nm and 5.36 Å, respectively. It was also found that the synthesis under 7% of Bi-stoichiometric excess inhibited the formation of the parasitic phases after annealing the intermediate produced in ethylene glycol medium. The saturation magnetization of the powders annealed at 700°C were 0.15 emu/g and 0.17 emu/g when the BFO intermediates were formed in ethylene glycol and acetic acid media, respectively. The corresponding coercivity values were 6 Oe and 21 Oe.
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50

Raeside, J. I., R. L. Renaud, R. M. Friendship, and M. W. Khalil. "Secretion of 19-hydroxyandrostenedione and 19-hydroxytestosterone by porcine Leydig cells in vitro and in vivo." Journal of Endocrinology 137, no. 2 (May 1993): 281–89. http://dx.doi.org/10.1677/joe.0.1370281.

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ABSTRACT 19-Hydroxytestosterone and 19-hydroxyandrostenedione have been identified as secretory products of the testes in the mature male domestic pig. Their isolation and identification were made by reverse-phase high-performance liquid chromatography and capillary gas chromatography-mass spectrometry (CGC-MS) of extracts from testicular vein blood and media of incubations with Leydig cells. Blood was collected from veins on the surface of the testes of anaesthetized boars. Collagenase-dispersed Percoll-purified cells (> 90% pure) were incubated (20 × 106 cells/flask) with androstenedione (8·75 μmol/l) or [3H]androstenedione (5 × 106 c.p.m.) for < 60 min. Steroids were recovered from plasma or media by solid-phase extraction and the unconjugated fractions chromatographed isocratically in two solvent systems (acetonitrile: water, 37:63 (v/v) and methanol: water, 70:30 (v/v)) before CGC-MS analysis. 19-Hydroxy-testosterone was present in greater quantities than 19-hydroxyandrostenedione in testicular vein blood; it was also seen as a quantitatively significant metabolite of unlabelled and radioactive androstenedione in the incubation studies. The demonstration of the secretion of 19-hydroxyandrogens from porcine testes thus raises questions concerning the physiological significance of a testicular, rather than an adrenal, secretion of these compounds. Journal of Endocrinology (1993) 137, 281–289
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