Surface active ionic liquids: Study of the micellar properties of 1-(1-alkyl)-3-methylimidazolium chlorides and comparison with structurally related surfactants

The impetus for the increasing interest in studying surface active ionic liquids (SAILs; ionic liquids with long-chain ""tails"") is the enormous potential for their applications, e.g., in nanotechnology and biomedicine. The progress in these fields rests on understanding the relationship between surfactant structure and solution properties, hence applications. This need has prompted us to extend our previous study on 1-(1-hexadecyl)-3-methylimidazolium chloride to 1-(1-alkyl)-3-methylimidazolium chlorides, with alkyl chains containing 10, 12, and 14 carbons. In addition to investigating relevant micellar properties, we have compared the solution properties of the imidazolium-based surfactants with: 1-(1-alkyl)pyridinium chlorides, and benzyl (2-acylaminoethyl)dimethylammonium chlorides. The former series carries a heterocyclic ring head-group, but does not possess a hydrogen that is as acidic as H2 of the imidazolium ring. The latter series carries an aromatic ring, a quaternary nitrogen and (a hydrogen-bond forming) amide group. The properties of the imidazolium and pyridinium surfactants were determined in the temperature range from 15 to 75 degrees C. The techniques employed were conductivity, isothermal titration calorimetry, and static light scattering. The results showed the important effects of the interactions in the interfacial region on the micellar properties over the temperature range studied. (C) 2011 Elsevier Inc. All rights reserved.

Micellar properties of surface active ionic liquids: A comparison of 1-hexadecyl-3-methylimidazolium chloride with structurally related cationic surfactants

Ionic liquids, ILs, carrying long-chain alkyl groups are surface active, SAIIs. We investigated the micellar properties of the SAIL 1-hexadecyl-3-methylimidazolium chloride, C(16)MeImCl, and compared the data with 1-hexadecylpyridinium chloride, C(16)PYCl, and benzyl (3-hexadecanoylaminoethyl)dimethylammonium chloride, C(15)AEtBzMe(2)Cl. The properties compared include critical micelle concentration, cmc; thermodynamic parameters of micellization; empirical polarity and water concentrations in the interfacial regions. In the temperature range from 15 to 75 degrees C, the order of cmc in H(2)O and in D(2)O is C(16)PYCl > C(16)MeImCl > C(15)AEtBzMe(2)Cl. The enthalpies of micellization, Delta H(mic)(degrees), were calculated indirectly from by use of the van`t Hoff treatment; directly by isothermal titration calorimetry, ITC. Calculation of the degree of counter-ion dissociation, alpha(mic), from conductivity measurements, by use of Evans equation requires knowledge of the aggregation numbers, N(agg), at different temperatures. We have introduced a reliable method for carrying out this calculation, based on the volume and length of the monomer, and the dependence of N(agg) on temperature. The N(agg) calculated for C(16)PyCl and C(16)MeImCl were corroborated by light scattering measurements. Conductivity- and ITC-based Delta H(mic)(degrees) do not agree; reasons for this discrepancy are discussed. Micelle formation is entropy driven: at all studied temperatures for C(16)MeImCl; only up to 65 degrees C for C(16)PyCl; and up to 55 degrees C for C(15)AEtBzMe(2)Cl. All these data can be rationalized by considering hydrogen-bonding between the head-ions of the monomers in the micellar aggregate. The empirical polarities and concentrations of interfacial water were found to be independent of the nature of the head-group. (C) 2010 Elsevier Inc. All rights reserved.

Espectroscopia de correlação bidimensional generalizada e sample-sample aplicada ao estudo da tripsina pancreática bovina

Pós-graduação em Biofísica Molecular - IBILCE

Interpretation of the temperature dependence of equilibrium and rate constants

The objective of this review is to draw attention to potential pitfalls in attempts to glean mechanistic information from the magnitudes of standard enthalpies and entropies derived from the temperature dependence of equilibrium and rate constants for protein interactions. Problems arise because the minimalist model that suffices to describe the energy differences between initial and final states usually comprises a set of linked equilibria, each of which is characterized by its own energetics. For example, because the overall standard enthalpy is a composite of those individual values, a positive magnitude for AHO can still arise despite all reactions within the subset being characterized by negative enthalpy changes: designation of the reaction as being entropy driven is thus equivocal. An experimenter must always bear in mind the fact that any mechanistic interpretation of the magnitudes of thermodynamic parameters refers to the reaction model rather than the experimental system For the same reason there is little point in subjecting the temperature dependence of rate constants for protein interactions to transition-state analysis. If comparisons with reported values of standard enthalpy and entropy of activation are needed, they are readily calculated from the empirical Arrhenius parameters. Copyright (c) 2006 John Wiley & Sons, Ltd.

Measurement and correlation of the solubility of telmisartan (form A) in nine different solvents from 277.85 to 338.35 K

The solubility of telmisartan (form A) in nine organic solvents (chloroform, dichloromethane, ethanol, toluene, benzene, 2-propanol, ethyl acetate, methanol and acetone) was determined by a laser monitoring technique at temperatures from 277.85 to 338.35 K. The solubility of telmisartan (form A) in all of the nine solvents increased with temperature as did the rates at which the solubility increased except in chloroform and dichloromethane. The mole fraction solubility in chloroform is higher than that in dichloromethane, which are both one order of magnitude higher than those in the other seven solvents at the experimental temperatures. The solubility data were correlated with the modified Apelblat equation and λh equations. The results show that the λh equation is in better agreement with the experimental data than the Apelblat equation. The relative root mean square deviations (σ) of the λh equation are in the range from 0.004 to 0.45 %. The dissolution enthalpies, entropies and Gibbs energies of telmisartan in these solvents were estimated by the Van’t Hoff equation and the Gibbs equation. The melting point and the fusion enthalpy of telmisartan were determined by differential scanning calorimetry.

Determinação da energia de ativação e pureza de medicamentos de referência, genérico e similar utilizando técnicas termoanalíticas

In this work, the reference drugs, generic and similar to the active ingredients acetylsalicylic acid, paracetamol, captopril, hydrochlorothiazide and mebendazole were purchased from local pharmacies and studied by thermogravimetry (TG) and Differential Scanning Calorimetry (DSC). Thermal decomposition was assessed to obtain from the Ozawa method the activation energy in inert atmosphere (nitrogen), using three different heating ratios (5, 10 and 20 o C min-1). The pharmaceutical formulation of the AAS reference was the one who presented different from the others (generic and similar) Thermogravimetric profile indicating likely interaction between the active ingredient and excipients. Was observed at the heating rate of the inverse temperature that no linearity of the data, ie, there was no correlation between the percentage of mass loss and the activation energy involved in the thermal decomposition of the pharmaceutical formulation of the AAS reference log graph. The analysis by differential scanning calorimetry was performed in nitrogen atmosphere with a heating rate of 10 ° C min-1. In the analysis of these same drugs, the data curves found on the melting point were, except for hydrochlorothiazide, are consistent with the literature. Hydrochlorothiazide presented a melting point well below that found in the literature, which may be justified due to the interaction of the active ingredient with the excipient lactose. In the study of purity, using the Van't Hoff equation, the reference drugs hydrochlorothiazide and mebendazole reference generic and showed similar impurity content below the limit established that this equation must be greater than 2.5 mol%

Nurses’ clinical communication skills

Abstract Background: Providing nursing care involves an interpersonal relationship between the nurse and the patient which is created through communication. The importance of clinical communication skills is a current priority when it comes to health care workers’ education and training and has been attracting more and more attention. As a consequence clinical communication skills are now present in more and more academic programmes. Objectives: To assess nurses’ clinical communication skills; to identify the variables that might inluence the clinical communication skills; to analyse nurses’ perspective regarding the training in the clinical communication ield. Material and methods: Quantitative, non-experimental, descriptive and correlational and crosssectional study. We used the questionnaire to collect socio-demographic and professional data, and the Clinical Communication Skills Scale based on the Kalamazoo Consensus Statement (KCS)1,2 and which had already been used in Portugal.3 The sample was formed by 275 practitioner nurses who have been working in health care institutions located in the center of Portugal. Results: The Scale we used presents 5 factors that explain 64.33% of the total variation: To in‑ volve the patient; To facilitate dialogue; To understand concerns; To communicate in an asser‑ tive way; To carry out the interview. The majority of the nurses consider that the training they had in the communication skills ield during their nursing course was good or very good, however we could see that 23.3% think it was mediocre. Almost all of them (98.9%) agree that there should be a better and more speciic training in the ield of clinical communication skills as far, as nurses as concerned. Nurses who had training in this area, older nurses, those who work directly with patients and those who have been working for a longer period of time show better communication skills. Conclusion: Although they think that the training they has was good, we could conirm that there was a deicit in nurses’ clinical communication skills and that nurses themselves refer they need more training in this area. Data point out to a more signiicant investment in clinical communication as far as nurses’ training is concerned and they suggest the promotion of lifelong learning opportunities in this area.

Correlation between Hoff test performance, body composition and aerobic and anaerobic fitness in professional soccer players

Purpose The purpose of the study was to investigate a possible association between the distance covered in the Hoff test with parameters of maximal oxygen uptake (V_O2MAX), anaerobic threshold, anaerobic fitness, and body composition of professional adult soccer players. Methods Twenty-five professional soccer players (20 ± 3 years) participated in the study. On different days the athletes performed: a graded incremental exercise test in a laboratory to measure V_O2MAX; a specific soccer field test called the Hoff test; a running anaerobic sprint test (RAST); an incremental test on an oval circuit to determine the velocity relative to anaerobic threshold (VAnT) and an estimation of body composition. Results The average V_O2MAX corresponded to 4.1 ± 0.1 L min-1 (54.1 ± 1.2 mL kg-1 min-1 ). The average distance covered during the Hoff test was 1,442.4 ± 30.0 m. The distance covered during the Hoff test showed significant correlations with absolute and expressed in an appropriated scale V_O2MAX (r = 0.44, p = 0.02; r = 0.42, p = 0.02, respectively) while no significant differences were found with body composition, VAnT and RAST variables. Conclusions The present study demonstrated that the distance covered during the Hoff test has weak correlation with V_O2MAX determined in treadmill running, and no correlation with VAnT, body composition and RAST outcomes, probably due to the non-specificity of the proposed tests when associated with the Hoff test.

Utilização da distância total percorrida no teste específico de hoff como preditor da velocidade de limiar anaeróbio no futebol

OBJECTIVE: To verify the use of maximal running distance performed on Hoff test to predict the anaerobic threshold speed (sAnT). METHODS: Ten young soccer players (age of 17 ± 1 years and body mass of 64.3 ± 2.1 kg) were subjects of the study. The subjects performed 12-min test, lactate minimum test to estimate the anaerobic threshold speed and a field test called Hoff. The purpose of Hoff test was to cover the maximum distance during a period of 10min moving a soccer ball through the track by dribbling. RESULTS: The distance covered during 12-min was 2673.2 ± 64.7 m, the sAnT was 11.6 ± 0.3 km.h-1 and distance covered during test Hoff test was 1458.7 ± 49.6 m. The distance covered during Hoff test was not significantly correlated with sAnT (r = -0.20; P > 0.05) and distance covered during 12-min test (r = -0.15; P > 0.05). The sAnT did not differ of speed correspondent 90% at 12-min speed and they were statistically correlated (r = 0.65). CONCLUSION: Thus, we concluded that maximal distance covered during Hoff test cannot provides a valid prediction of the anaerobic threshold speed.

Identificação de bandas espectrais para detecção de cultura de cana-de-açúcar sadia e doente utilizando câmara hiperespectral embarcada em VANT

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Montagem e avaliação de um sistema de varredura a LASER embarcado em VANT

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Montagem e avaliação de um sistema de varredura a LASER embarcado em VANT

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Johann Hoff und Johann Hoff, oder: Die Wunder des Malz-Extracts : ägyptische Burleske mit antiken Couplets in 1 Akt

von Eduard Hermann Schaute

Joseph Frölig : Privelegierter Sau-Magen und Hoff-Narr

Original knapp beschnitten

Karl Pichler, Philipp Hoff

Signatur des Originals: S 36/F01513