Unraveling Dynamical Heterogeneity in the Ionic Liquid 1-Butyl-3-methylimidazolium Chloride

Heterogeneous dynamics within a time range of nanoseconds was investigated by molecular dynamics (MD) simulations of 1 -butyl-3-methylimidazolium chloride ([bmim]Cl). After identifying groups of fast and slow ions, it was shown that the separation between the location of the center of mass and the center of charge of cations, d(CMCC), is a signature of such difference in ionic mobility. The distance d(CMCC) can be used as a signature because it relaxes in the time window of the dynamical heterogeneity. The relationship between the parameter dcmcc and conformations of the side alkyl chain in [bmim] is discussed. Since the relatively slow relaxation of dcmcc is a consequence of coexisting polar and nonpolar domains in the bulk, the MD simulations reveal a subtle interplay between structural and dynamical heterogeneity in ionic liquids.

Application of 1-Allyl-3-(1-butyl)imidazolium Chloride in the Synthesis of Cellulose Esters: Properties of the Ionic Liquid, and Comparison with Other Solvents

The ionic liquid (IL), 1-allyl-3-(1-butyl)imidazolium chloride (AlBuImCl), has been synthesized and its properties determined. Increase in the temperature increased its conductivity and decreased its density, polarity, and viscosity. Microcrystalline cellulose (MCC), dissolves in thisIL by heating at 80 degrees C; this did not affect its degree of polymerization, decreased its index of crystallinity (Ic), and changed in morphology after regeneration. Convenient acylation of MCC was achieved by using 50% excess anhydride at 80 degrees C, for 24 or 48 h for acetic and butyric anhydride, respectively. The composition of the mixed esters depended on the initial ratio of the anhydrides, and their order of addition.

First study on the thermo-solvatochromism in aqueous 1-(1-butyl)-3-methylimidazolium tetrafluoroborate: A comparison between the solvation by an ionic liquid and by aqueous alcohols

The thermo-solvatochrornic behaviors of 2,6-diphenyl-4-(2,4,6-triphenylpyridinium-1-yl) phenolate, RB; 2,6-dichloro-4-(2,4,6-triphenyloyridinium-1-yl) phenolate, WB; 2,6-dibromo-4-[(E)-2-(1-methylpyridinium-4-yl)ethenyl] phenolate, MePMBr(2); 2,6-dibromo-4-[(E)-2-(1-n-octylpyridinium-4-yl)ethenyl] phenolate, OcPMBr(2), have been investigated in binary mixtures of the ionic liquid, IL, 1-(1-butyl)-3-methylimidazolium tetrafluorborate, [BuMeIm][BF(4)], and water (W), in the temperature range from 10 to 60 degrees C. Plots of the empirical solvent polarities, ET (probe) in kcal mol(-1), versus the mole fraction of water in the binary mixture, chi(w) showed nonlinear, i.e., nonideal behavior. Solvation by these IL-W mixtures shows the following similarities to that by aqueous aliphatic alcohols: The same solvation model can be conveniently employed to treat the data obtained; it is based on the presence in the system-bulk medium and probe solvation shell of IL, W, and the ""complex"" solvent 1:1 IL-W. The origin of the nonideal solvation behavior appears to be the same, preferential solvation of the probe, in particular by the complex solvent. The strength of association of the IL-W complex, and the polarity of the IL are situated between the corresponding values of aqueous methanol and aqueous ethanol. Temperature increase causes a gradual desolvation of all probes employed. A difference between solvation by IL-W and aqueous alcohols is that probe-solvent hydrophobic interactions appear to play a minor role in case of the former mixture, probably because solvation is dominated by hydrogen-bonding and Coulombic interactions between the ions of the IL and the zwitterionic probes.

Raman spectra of polymer electrolytes based on poly(ethylene glycol) dimethyl ether, lithium perchlorate, and the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate

Raman spectra of polymer electrolytes based on poly(ethylene glycol) dimethyl ether (PEGdME) with LiClO(4), PEGdME/LiClO(4), and the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate, PEGdME/[bmim]PF(6), are compared. Raman spectroscopy suggests stronger interactions in PEGdME/LiClO(4) than PEGdmE/[bmim]PF(6), thus corroborating previous results obtained by molecular dynamics simulations. Quantum Chemistry methods have been used to calculate vibrational frequencies and the equilibrium structure of segments of the polymer chain around the cation. A consistent picture has been obtained from Raman spectroscopy, density functional theory (DFT) calculations, and molecular dynamics simulations for these polymer electrolytes. (C) 2010 Elsevier B.V. All rights reserved.

Aromatic nitro substitution reaction between 4-nitro-N-n-butyl-1,8-naphthalimide and n-heptanethiol in water-methanol binary mixtures

The second-order rate constants of thiolysis by n-heptanethiol on 4-nitro-N-n-butyl-1,8-naphthalimide (4NBN) are strongly affected by the water-methanol binary mixture composition reaching its maximum at around 50% mole fraction. In parallel solvent effects on 4NBN absorption molar extinction coefficient also shows a maximum at this composition region. From the spectroscopic study of reactant and product and the known H-bond capacity of the mixture a rationalization that involves specific solvent H-donor interaction with the nitro group is proposed to explain the kinetic data. Present findings also show a convenient methodology to obtain strongly fluorescent imides, valuable for peptide and analogs labeling as well as for thio-naphthalimide derivatives preparations. Copyright (C) 2008 John Wiley & Sons, Ltd.

Evaluation of n-Butyl Cyanoacrylate Adhesive in Rat Subcutaneous Tissue

Background Tissue adhesives have been widely used for wound closure, especially in children, because they are painless, fast, and easy to use and result in minimal scarring.Objective To analyze the biocompatibility of an adhesive based on n-butyl-cyanoacrylate in the subcutaneous tissue of rats.Materials and Methods Two surgical sites were prepared (approximately 3 cm apart): one on the left side of the animal and the other on the right side); polyethylene tubes were implanted in each surgical site. The tube on the left was filled with n-butyl-cyanoacrylate (treated group) and the tube on the right side was unfilled (control group). After 7, 30, and 120 days, the animals were killed, and the specimens were processed for histologic analysis.Results No significant inflammatory reaction occurred in the treated group, showing results similar to the control group.Conclusion This adhesive based on n-butyl-cyanoacrylate is biocompatible in the subcutaneous tissue of rats.

Long-term effects of developmental exposure to di-n-butyl-phthalate (DBP) on rat prostate: Proliferative and inflammatory disorders and a possible role of androgens

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Reproductive development and function of female rats exposed to di-eta-butyl-phthalate (DBP) in utero and during lactation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Functional and Morphological Reproductive Aspects in Male Rats Exposed to Di-n-Butyl Phthalate (DBP) in Utero and During Lactation

The potential adverse reproductive effects, with emphasis on the epididymis, of in utero and lactational exposure to 100 mg/kg/d di-n-butyl phthalate (DBP) in adult male rat offspring were investigated. The fetal testis histopathology was also determined. The selected endpoints included reproductive organ weights, sperm motility and morphology, sperm epididymal transit time, sperm quantity in the testis and epididymis, hormonal status, fetal testis and epididymal histopathology and stereology, and androgen receptor (AR), aquaporin 9 (AQP9), and Ki-67 immunoreactivities. Pregnant females were divided into two groups: control (C) and treated (T). The treated females received DBP (100 mg/kg/d, by gavage) from gestation day (GD) 12 to postnatal day (PND) 21, while control dams received the vehicle. Some pregnant dams were killed by decapitation on GD20, and testes from male fetuses were collected for histopathogy. Male rats from other dams were killed at PND 90. Fetal testes from treated group showed Leydig-cell clusters, presence of multinucleated germinative cells, and increase of the interstitial component. Testosterone levels and reproductive organ weights were similar between the treated and control adult groups. DBP treatment did not markedly affect relative proportions of epithelial, stromal, or luminal compartments in the epididymis; sperm counts in the testis and epididymis; sperm transit time; or sperm morphology and motility in adult rats. The AR and AQP9 immunoreactivities and proliferation index were similar for the two groups. These results showed that fetal testes were affected by DBP as evidenced by testicular histopathologic alterations, but reproductive parameters and epididymal structure/function were not significantly altered in the adult animals exposed to 100 mg/kg DBP in utero and during lactation.

Butyl hydroxytoluene (BHT)-induced oxidative stress: Effects on serum lipids and cardiac energy metabolism in rats

Recent lines of evidences indicate that several pathological conditions, as cardiovascular diseases, are associated with oxidative stress. In order to validate a butylated hydroxytoluene (BHT)-induced experimental model of oxidative stress in the cardiac tissue and serum lipids, 12 Wistar rats were divided into two groups, a control group and the BHT group, Which received BHT i.p. twice a week (1500 mg/kg body Weight) during 30 days. BHT group presented lower body weight gain and heart weight. BHT induced toxic effects on serum through increased triacylglycerols (TG), VLDL and LDL-cholesterol concentrations. The heart of BHT animals showed alteration of antioxidant defenses and increased concentrations of lipid hydroperoxides, indicating elevated lipoperoxidation. TG concentrations and lactate dehydrogenase activities were elevated in the cardiac Muscle of BHT animals. Thus, long-term administration of BHT is capable to induce oxidative and metabolic alterations similarly to some pathological disorders, constituting an efficient experimental model to health scientific research. (c) 2005 Elsevier GrnbH. All rights reserved.

Separation and partitioning of Green Fluorescent Protein from Escherichia coli homogenate in poly(ethylene glycol)/sodium-poly(acrylate) aqueous two-phase systems

The partitioning of Green Fluorescent Protein (GFP) in poly(ethylene glycol)/Na-poly(acrylate) aqueous two-phase systems (PEG/NaPA-ATPS) has been investigated. The aqueous two-phase systems are formed by mixing the polymers with a salt and a protein solution. The protein partitioning in the two-phase system was investigated at 25 degrees C. The concentration of the GFP was measured by fluorimetry. It was found that the partitioning of GFP depends on the salt type, pH and concentration of PEG. The data indicates that GFP partitions more strongly to the PEG phase in presence of Na2SO4 relative to NaCl. Furthermore, the GFP partitions more to the PEG phase at higher pH. The partition to the PEG phase is strongly favoured in systems with larger tie-line lengths (i.e. systems with higher polymer concentrations). The molecular weight of PEG is important since the partition coefficient (K) of GFP gradually decreases with increasing PEG size, from K ca. 300-400 for PEG 400 to K equal to 1.19 for PEG 8000. A separation process was developed where GFP was separated from a homogenate in two extraction steps: the GFP is first partitioned to the PEG phase in a PEG 3000/NaPA 8000 system containing 3 wt% Na2SO4, where the K value of GFP was 8. The GFP is then re-extracted to a salt phase formed by mixing the previous top-phase with a Na2SO4 solution. The K-value of GFP in this back-extraction was 0.22. The total recovery based on the start material was 74%. (c) 2008 Elsevier B.V. All rights reserved.

Plasmid DNA partitioning and separation using poly(ethylene glycol)/poly(acrylate)/salt aqueous two-phase systems

Phase diagrams of poly(ethylene glycol)/polyacrylate/Na2SO4 systems have been investigated with respect to polymer size and pH. Plasmid DNA from Escherichia coil can depending on pH and polymer molecular weight be directed to a poly(ethylene glycol) or to a polyacrylate-rich phase in an aqueous two-phase system formed by these polymers. Bovine serum albumin (BSA) and E. coil homogenate proteins can be directed opposite to the plasmid partitioning in these systems. Two bioseparation processes have been developed where in the final step the pDNA is partitioned to a salt-rich phase giving a total process yield of 60-70%. In one of them the pDNA is partitioned between the polyacrylate and PEG-phases in order to remove proteins. In a more simplified process the plasmid is partitioned to a PEG-phase and back-extracted into a Na2SO4-rich phase. The novel polyacrylate/PEG system allows a strong change of the partitioning between the phases with relatively small changes in composition or pH. (C) 2012 Elsevier B.V. All rights reserved.

Evaluation of the effect of hyoscine-N-butyl bromide on the cardiovascular actions of detomidine in the horse

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Absence of promoting potential of bracken fern (Pteridium aquilinum) in rat urinary bladder carcinogenesis induced by N-butyl-N-(4-hydroxybutyl)-nitrosamine and uracil

Conventional studies on bracken fern (Pteridium aquilinum; PA) carcinogenicity have used high dietary concentrations (around 30%) and long-term exposure (up to 52-70 weeks) without consideration of the multistep character of the chemical carcinogenesis process. The present study evaluated specifically the promoting potential of 3-5% dietary crude PA in the rat urinary bladder mucosa in a 32-week-long initiation-promotion assay for chemical carcinogenesis. Initiation of urothelial carcinogenesis was accomplished with N-butyl-N-(4-hydroxybutyl)-nitrosamine (BBN). Uracil (U) was provided through the diet in order to expand the population of initiated cells. Seven groups (C) of male Wistar rats were submitted to the following treatments: G1 = BBN (n = 8); G2 = U (n = 10); G3 = BBN-U (n = 9); G4 = BBN-PA-U-PA (n = 16); G5 = PA (n = 8); G6 = BBN-PA (n = 10); G7 = PA-U-PA (n = 12). At the end of the experiment rats presenting epithelial papillary or nodular hyperplasia (PNH), papillomas (PAP), or simultaneous PNH plus PAP numbered, respectively G1: 2-0-1; G2: 0-0-0; G3: 3-0-2; G4: 4-3-2; G5: 1-0-1; G6: 8-0-0; and G7: 0-0-0, with no significant differences in the incidence of lesions among the groups. More frequent and more severe lesions occurred in BBN-initiated animals, predominantly in those also exposed to uracil (G3 and G4). Low-dose crude bracken fern in the diet does not promote rat urinary bladder carcinogenesis after a 32-week period of exposure, even when the initiated urothelial cell population has been expanded through a mechanical stimulus. (C) 1995 Wiley-Liss, Inc.

The electrochemical cleavage of the nitrobenzoyl group from butyl nitrobenzoates in N,N-dimethylformamide

The applicability of the nitrobenzoyl group [NO2C6H4CO-] to protecting the functional hydroxyl group was investigated through study of the electrochemical behaviour of the butyl 4-, 3- and 2-nitrobenzoate compounds. These isomers are reduced in two cathodic steps. The first, at potentials of ca. -0.9 V vs. SCE, is attributed to the formation of rather stable anion radicals, involving one-electron transfer. The second, at potentials of ca. -1.7 V vs. SCE, occurs with a two-electron transfer in an ECE process, in which the dianion produced undergoes scission of the C-O bond giving n-butanoate ions with high yields (similar to 80%)