Effect of Temperature on the Yields of Final Products in the γ-Radiolysis of Formaldehyde Solutions in C1–C3 Alkanols

The effect of temperature on the yields of 1,2-alkanediols in the -radiolysis of the methanol(or ethanol)–formaldehyde (0.9 M) systems and on the yields of 1,2-alkanediols, carbonyl compounds, methanol, and ethanol in the -radiolysis of the 1-propanol(or 2-propanol)–formaldehyde (1 M) systems was studied over the range 373–473 K. It was found that the temperature dependence of the yields of 1,2-butanediol and 2-methyl-1,2-propanediol exhibited maximums at 423 and 373 K, respectively.     

Effect of Ionic Strength and Temperature on the Protonation of Oxidized Glutathione

The protonation constants for oxidized glutathione, H _i−1L^(4−i+1)−, K _i ^H=[H _i L⁽⁴⁻ⁱ⁾⁻]/[H _i−1L^(4−i+1)−][H⁺] i=1,2,…,6 have been measured at 5, 25 and 45 °C as a function of the ionic strength (0.1 to 5.4 mol⋅[kg(H₂O)]⁻¹) in NaCl solutions. The effect of ionic strength on the measured protonation constants has been used to determine the thermodynamic values (K _i ^H0) and the enthalpy (ΔH _i ) for the dissociation reaction using the SIT model and Pitzer equations. The SIT (ε) and Pitzer parameters (β ⁽⁰⁾, β ⁽¹⁾ and C) for the dissociation products (L⁴⁻, HL³⁻, H₂L²⁻, H₃L⁻, H₄L, H₅L⁺, H₆L²⁺) have been determined as a function of temperature. These results can be used to examine the effect of ionic strength and temperature on glutathione in aqueous solutions with NaCl as the major component (body fluids, seawater and brines).     

Effect of Temperature on the Solubility of Short-Chain Carboxylic Acids in Water

The aqueous solubilities of pentanoic and hexanoic acids were measured between 298.15 and 333.15 K at intervals of 5.00 K. Nonlinear dependences were found for the variation of solubility with temperature. The temperature dependences of the solubility of the acids in water are described by nonlinear van’t Hoff plots. Experimental data were fitted by the method of least-squares to a second-order polynomial equation, which was then used to determine the differential solution enthalpies at selected temperatures. The values for the apparent Gibbs energy and the apparent entropy of solution are calculated.     

The Role of ΔFosB on the Pro-survival Effect of PTHrP in Goat Mammary Epithelial Cells

The mechanism of regulation mammary epithelial cell number in ruminant is not fully understood, but is thought to be dependent on the balance of cell proliferation and cell apoptosis. Parathyroid hormone-related protein (PTHrP) could express in mammary epithelial cells and breast cancer cells, and has been reported to regulate cell survival. Here, we showed that PTHrP induced cell proliferation and increased the expression of CyclinD1 and proliferating cell nuclear antigen (PCNA) in goat mammary epithelial cells (GMEC). PTHrP increased the mRNA levels of anti-apoptosis genes Bcl-2 and Bcl-xl, and protected GMEC from apoptosis. We also found ΔFosB, an alternative splicing of finkel-biskis-jinkins murine osteosarcoma B (fosB), inhibited GMEC apoptosis, and induced cell proliferation with increased Bcl-2/Bax and Bcl-xl/Bax ratios. Interestingly, ΔFosB could further promote the pro-survival effect of PTHrP, and the Bcl-2/Bax and Bcl-xl/Bax ratios showed higher levels. We conclude that the pro-survival role of PTHrP in GMEC may be regulated by ΔFosB.     

Effect of Hydrogenation on Ring C of Flavonols on Their Affinity for Bovine Serum Albumin

In this paper, the effect of hydrogenation on ring C of flavonols on the affinity for bovine serum albumin was investigated. Two differently substituted B-ring hydroxylation flavonols (myricetin and quercetin) and their dihydrides (dihydromyricetin and dihydroquercetin) were used to study their affinities for BSA by quenching the intrinsic BSA fluorescence in solution. From the spectra, the bimolecular quenching constants, the binding constants, the number of binding sites and the binding distances were calculated. The hydroxylation on ring B and hydrogenation on ring C of flavonols significantly affected the binding/quenching process; in general, the hydroxylation increased the affinity and the hydrogenation decreased the affinity. For myricetin and quercetin, the binding constants (K _a) for BSA were 1.84×10⁸ L⋅mol⁻¹ and 3.83×10⁷ L⋅mol⁻¹. For dihydromyricetin, the binding constant was 1.36×10⁴ L⋅mol⁻¹, while dihydroquercetin hardly quenched the BSA intrinsic fluorescence. These results showed that hydrogen bonding and conjugative effects may play an important role in binding of flavonols to BSA. These results also showed that the properties of flavonols are related to their chemical structure.     

Study on the Synergism Effect of Lomefloxacin and Ofloxacin for Bovine Serum Albumin in Solution by Spectroscopic Techniques

Both lomefloxacin (LOM) and ofloxacin (OFL) have a powerful ability to quench the fluorescence of bovine serum albumin (BSA). The fluorescence quenching action is much stronger when the two drugs coexist. The synergism between LOM and OFL was studied using fluorescence and ultraviolet spectroscopy under imitated physiological conditions. The results show that static quenching and non-radiation energy transfer are the main reasons for the fluorescence quenching. The synergism results in both the reduction of the binding stability between drugs and BSA and an increase of the free drug concentration, which will increase the efficacy of drugs. The thermodynamic parameters at different temperatures were calculated and the binding distances r between the drugs and BSA were obtained based on Försters theory of non-radiation energy transfer. The synchronous fluorescence spectra indicated that the effect of synergism affected the conformation of BSA.     

Effect of the Charge and the Nature of Both Cations and Anions on the Solubility of Zwitterionic Amino Acids,Measurements and Modeling

The effect of the charge and the nature of both the cations and the anions of some electrolytic salts: sodium fluoride (NaF), potassium fluoride (KF), sodium bromide (NaBr), potassium bromide (KBr), sodium iodide (NaI), potassium iodide (KI), sodium sulfate (Na₂SO₄), potassium sulfate (K₂SO₄), calcium chloride (CaCl₂), and barium chloride (BaCl₂), on the solubility of zwitterionic amino acids (glycine, DL-alanine, DL-valine, and DL-serine) in aqueous solutions at 298.15 K are studied and discussed. A salting-in effect is observed for all amino acids under investigation with all electrolytes used in the present study, except for DL-alanine and DL-valine in aqueous solutions containing sodium fluoride where a salting-out effect was observed. The orders of the effect of the nature and the charge of both the anions and the cations are: F^- < Cl^- < Br^- < I^- < NO₃^- < SO₄^2-\mathrm{F}^{-}<{}\mathrm{Cl}^{-}<{}\mathrm{Br}^{-}<{}\mathrm{I}^{-}<\mathrm{NO}_{3}^{-}<{}\mathrm{SO}_{4}^{2-} with both sodium and potassium cations; Na⁺<K⁺<Ca²⁺<Ba²⁺ with chloride anion.     

Effect of pressure on the solubility of naphthalene in water at 25°C

Solubility of naphthalene in water was measured at 25°C and pressures up to 200 MPa. The solubility decreased with increasing pressure. From the pressure coefficient of the solubility, the volume change V accompanying the dissolution was estimated as 13.8±0.4 cm ³ -mol ^–1 . Further we estimated the volume change V _CH accompanying hydrophobic hydration as –0.1±0.6 cm ³ -mol ^–1 using the V value, the molar volume of crystalline naphthalene, and the partial molar volume of naphthalene in n-heptane. This V _CH is much larger (i.e., less negative) than that for hydrophobic hydration of alkyl-chain compounds and suggests that the hydration structure of naphthalene differs from that of alkyl-chain compounds.     

Microwave frequency effects on dielectric properties of some common solvents and on microwave-assisted syntheses: 2-Allylphenol and the C12–C2–C12 Gemini surfactant

Microwave radiation emitted at a frequency of 915 MHz and 5.8 GHz from a newly fabricated single-mode resonance microwave apparatus is herein proposed for use in microwave-assisted organic syntheses. The usefulness of 5.8-GHz microwaves is demonstrated by the solvent-free synthesis of 2-allylphenol through a Claisen rearrangement process, and by the synthesis of the C₁₂–C₂–C₁₂ Gemini surfactant in ethanol solvent undertaken to verify the usefulness of the 915-MHz frequency. These two model reactions have shown the advantage of these two microwave frequencies in that the observed efficiencies were greater than when employing the more commonly used 2.45-GHz microwaves. Dielectric parameters (dissipation factor: tan δ, dielectric constant: ε′, and dielectric loss: ε′′) have also been assessed for water and 22 common organic solvents typically used in organic syntheses, together with the temperature dependence of the dielectric parameters. Temperature–time profiles have been determined and rates of increase of temperature computed. The 5.8-GHz microwaves were effective in heating non-polar solvents, while the 915-MHz microwave frequency was most suitable for heating the alcohols.     

Effect of Solvent Characteristics on the Photophysics of Hydroxyl Aromatic Compounds

The effect of solvent characteristics on the absorption and emission properties of 1- and 2-naphthols have been studied and the results interpreted in terms of the general and specific solute-solvent interactions. Measurements were performed in several solvents and analysis of the absorption and emission wavelengths were made using Lippert’s model for general solvent effects. A near linear relationship between the Stokes shift (D[`(n)]\Delta\bar{\nu}) and the orientation polarizability (Δf) were observed for both 1- and 2-naphthols in most of the alkanols, thus showing evidence of a general solvent effect. However, in 1,4-dioxane–water mixtures the plots deviate from linearity indicating the dominance of specific solvent effects that are not included in Lippert’s equation. In the case of interactions between the fluorophores and dioxane–water mixtures, excess Stokes’ shifts are observed in the order of dioxane composition 10%>20%>30%>50%>60%>80%. This may be due to excited state proton transfer (ESPT) and the involvement of hydrogen bonding between the protic group of the fluorophore and the solvents.     

Effect of Dissolved CO_2 and Tetrahydrofuran on the Polymerization of Acrylic Acid

Recently,c0mpressedgaseshavebeenusedins0megasantisolventprocesses,suchasfractionati0n0fnaturaIproducts,recrystallization0forganicandin0rganicmaterials,andpolymerpr0cessing'2.WestudiedtheeffectofthedissovledsupercriticaICO=andTHFonthep0lymerizati0n0fAA.Itwasn0tfoundintheliterature.ExperimentalOnemlacrylicacidmonomer,O.O20ginitiator2,2'-azobis(is0butyronitrile)(AlBN),anddesiredam0unt0fTHFwereaddedintoanopticalcelloflOml.CO,wascharged,stirreduntilvap0r-liquidequilibriumwasreachedatabout30…     

Effect of Amines on the Surface Charge Properties of Iron Oxides

Specific studies detailing the effects of amines, used as pH control agents for corrosion inhibition in power plants, on the surface charge of iron oxides provide data to assess the mechanism of how these amines impact deposition rate. The current study was undertaken in order to determine accurately the dissociation constants of the relevant amines at Pressurized Water Reactor (PWR) operating conditions and to investigate the effect of sorption of two of these amines (morpholine and dimethylamine) by magnetite. The acid-dissociation equilibria of morpholine (MOR), dimethylamine (DMA) and ethanolamine (ETA) were measured potentiometrically with a hydrogen-electrode concentration cell (HECC) from 0 to 290 °C in sodium trifluoromethanesulfonate (NaTr) solutions at ionic strengths up to 1 mol⋅kg⁻¹. Magnetite surface titrations were performed at an ionic strength of 0.03 mol⋅kg⁻¹ (NaTr medium) in the presence or absence of morpholine and dimethylamine buffers over a wide range of pH and total amine concentrations at 150–250 °C. D.A. Palmer is retired.     

Adsorption and Inhibition Effect of Benzaldehyde Schiff Bases on Mild Steel Corrosion in 1 M HCl Medium

This article has been retracted.     

Cosolvent Effect on the Tautomerism of Ethyl Acetoacetate in Supercritical CO_2

There are some unique advantages for chemical reactions in SCFs. For example, reaction rates, yields, and selectivity can be tuned by pressure or small amount of cosolvent. SCFs can be used to replace environmentally undesirable solvents. It is not surprised that in recent years the use of SCFs as solvents for chemical reaction media has received much attention. However, mechanism for the effect of pressure and cosolvents on chemical reactions is not very clear. Tautomeric reactions are id…     

Effect of the Size of Polyacrylamide-Stabilized Palladium Nanoparticles Supported on γ-Fe2O3 on Their Catalytic Properties in the Hydrogenation of Phenylacetylene

Theoretical and Experimental Chemistry - Hydrogenation catalysts derived from palladium nanoparticles varying in size supported on maghemite (γ-Fe2O3) were obtained by varying the...     

Effect of Reaction Temperature and Pressure on the Metathesis Reaction between Ethene and 2-Butene to Propene on the WO3/Al2O3-HY Catalyst

Effect of reaction temperature and pressure on the metathesis reaction between ethene and 2-butene to propene was studied on the WO3/γ-Al2O3-HY catalyst. The activity is found to increase with elevated temperature and reaches a plateau at 150-240℃. After that, the activity undergoes a remarkable decrement at too high temperature. The effect of temperature is elucidated by the oxidation state of tungsten species. The evaluation results also indicate that the stability is dependent on this reaction parameter. Medium pressure (0.5-0.8 MPa) is favorable for stability, while atmospheric pressure or too high pressure (>1.0 MPa) deteriorates the stability. For explanation, UV Vis, FT-IR, O2-TPO, and TG techniques are used to characterize the spent catalysts.     

Effect of pulegone and pulegone oxide on the corrosion of steel in 1?M HCl

The inhibitive action of pulegone and pulegone oxide toward acid corrosion of steel in molar hydrochloric acid was studied by weight loss measurements, potentiodynamic polarization, and impedance spectroscopy (EIS) methods. The pulegone is extracted starting from oil of Pennyroyal Mint (Mentha pulegium). The natural compound was found to delay the corrosion rate. The pulegone oxide is prepared by oxidation of pulegone. The inhibition efficiency was found to increase with the inhibitor content to attain 81 and 75% at 5 g dm⁻³ for pulegone and pulegone oxide. The increase in temperature leads to an increase in the inhibition efficiency of the natural compared.     

Effect of the Grignard Reagent on the X→Csp Migration of the MR3 Group in HC≡CCH2XMR3 Compounds

The effect of the Grignard compounds (EtMgBr, PhMgBr, t-BuMgCl, cyclo-C₆H_{1 1}MgBr, and PhCÍÄCMgBr) on the isomerization of HCÍÄCCH₂XMR₃ into R₃MCÍÄCCH₂XH (M = Si, Ge; X = O, S) was studied. The efficiency of the 1,4-(Xarr;Csp)-migration of the R₃M group was shown to depend on the nucleophilicity of the Grignard compound and nature of the MÄX bond.