Aplicação de indentação instrumentada na caracterização mecânica de poliuretana derivada de óleo de mamona

Neste trabalho são investigadas as propriedades mecânicas de poliuretana derivada do óleo de mamona, utilizando a técnica de indentação instrumentada com penetradores de geometrias piramidal e esférica. Foi analisada a influência da forma do penetrador utilizado nos ensaios de indentação instrumentada para se obter valores das propriedades mecânicas de polímero derivado de óleo de mamona. Os penetradores utilizados são de pontas piramidais dos tipos Berkovich e canto de cubo e esférico de raio igual a 150 μm em um Nanoindenter XP TM com cargas aplicadas entre 1 e 200 mN. As penetrações variam de acordo com o formato do penetrador, sendo maiores para pontas agudas. A dureza e o módulo de elasticidade foram determinados, utilizando o método de Oliver e Pharr. Verificou-se que os valores medidos para a dureza são maiores para penetradores mais agudos. Os valores obtidos com a ponta piramidal Berkovich foram de 0,14 GPa para pequenas penetrações e 0,12 GPa para maiores penetrações. Já os valores obtidos com ponta canto de cubo foram 25 a 30% maiores. Isso está relacionado com os volumes das regiões que apresentam deformações plásticas elevadas, no caso de penetradores agudos comparados com os volumes das regiões que sofrem deformações viscoelásticas. A viscosidade aparente determinada, utilizando penetrador esférico em testes de força aplicada constante, é igual a (22 ± 2) × 10(12) Pa.s.

Influence of Phase Inversion on the Formation and Stability of One-Step Multiple Emulsions

A novel method of preparation of water-in-oil-in-micelle-containing water (W/O/W(m)) Multiple emulsions using the one-step emulsification method is reported. These multiple emulsions were normal (not temporary) and stable over a 60 day test period. Previously, reported multiple emulsion by the one-step method were abnormal systems that formed at the inversion point of simple emulsion (where there is an incompatibility in the Ostwald and Bancroft theories, and typically these are O/W/O systems). Pseudoternary phase diagrams and bidimensional process-composition (phase inversion) maps were constructed to assist in process and composition optimization. The surfactants used were PEG40 hydrogenated castor oil and sorbitan oleate, and mineral and vegetables oils were investigated. Physicochemical characterization studies showed experimentally, for the First time, the significance of the ultralow surface tension point oil multiple emulsion formation by one-step via phase inversion processes. Although the significance of ultralow surface tension has been speculated previously, to the best of our knowledge, this is the first experimental confirmation. The multiple emulsion system reported here was dependent not only upon the emulsification temperature, but also upon the component ratios, therefore both the emulsion phase inversion and the phase inversion temperature were considered to fully explain their formation. Accordingly, it is hypothesized that the formation of these normal multiple emulsions is not a result of a temporary incompatibility (at the inversion point) during simple emulsion preparation, as previously reported. Rather, these normal W/O/W(m) emulsions are a result of the simultaneous occurrence of catastrophic and transitional phase inversion processes. The formation of the primary emulsions (W/O) is in accordance with the Ostwald theory and the formation of the multiple emulsions (W/O/W(m)) is in agreement with the Bancroft theory.

Quantitative image analysis as a tool for Yarrowia lipolytica dimorphic growth evaluation in different culture media

Yarrowia lipolytica, a yeast strain with a huge biotechnological potential, capable to produce metabolites such as γ-decalactone, citric acid, intracellular lipids and enzymes, possesses the ability to change its morphology in response to environmental conditions. In the present study, a quantitative image analysis (QIA) procedure was developed for the identification and quantification of Y. lipolytica W29 and MTLY40-2P strains dimorphic growth, cultivated in batch cultures on hydrophilic (glucose and N-acetylglucosamine (GlcNAc) and hydrophobic (olive oil and castor oil) media. The morphological characterization of yeast cells by QIA techniques revealed that hydrophobic carbon sources, namely castor oil, should be preferred for both strains growth in the yeast single cell morphotype. On the other hand, hydrophilic sugars, namely glucose and GlcNAc caused a dimorphic transition growth towards the hyphae morphotype. Experiments for γ-decalactone production with MTLY40-2P strain in two distinct morphotypes (yeast single cells and hyphae cells) were also performed. The obtained results showed the adequacy of the proposed morphology monitoring tool in relation to each morphotype on the aroma production ability. The present work allowed establishing that QIA techniques can be a valuable tool for the identification of the best culture conditions for industrial processes implementation.

Riqueza em óleo nas sementes, amêndoas e cascas das bagas de mamona

This paper is a joined publication of the Depts. of Genetics and of Technology, of the E. S. A. "Luiz de Queiroz", Universidade de São Paulo, and deals with the variation of the percentage oil content in the whole seeds, the embryos and the seed-coat of 28 varieties of castor-beans (Ricinus communis, L.). Primarily, the authors, as a justification of this paper, make reference to the applications which castor-oil has in industry, medicine, etc. In accordance with the weight of 100 seeds, the varieties of castor-beans were classified into 3 classes : small seeds (100 seeds less than 30 g), medium seeds (100 seeds between 30 g and 60) and large seeds (100 seeds more than 60 g). The percentage of oil in the seed, embryo and seed-coat, the dimensions of the seeds and the weight of 100 seeds are given for every variety in table 1. In order to obtain an estimate of the variability for the methods of determination of the oil percentage, in the 3 differents parts of the seeds and also in the 3 groups of seeds, the coefficient of variability was calculate (table 2). It is showed that the variation in the seed and embryo is low and that in the seed-coat is very high. The analysis of variance, with regard to the difference among the 3 types of seeds (small, medium and large), among the 3 parts of the seed (whole seed, embryo and seed-coat) and residual error, is given in table 3. Only, the oil content of whole seeds among types of seeds was significant at the 5% level. The t test among the correspondent means is not significant for the difference between medium and large seeds is significant between both these types (medium and large) and small seeds. The fiducial limits in relation to the mean of the oil percentage in the 3 differents types of seed, show that there is one variety (n. 1013-2), which has a percentage of oil, in the medium type of seed, significantly at the 5% level (table 4), higher than the general mean. Since the distribution of the percentage of oil in the seedcoat is discontinuous, 5 groups were established (table 5). All the differences between groups are significant (table 6). For practical purposes, when we have to remove the seed coat, one should eliminate those varieties which loose at least 3% of oil by this procedure. There is a significant linear correlation at 5% level between the percentage of oil in the seed and in the embryo, of the smali and medium type of seeds (table 7), and also, when taking the 3 types together (lower part of table 7), one finds that the same is true. Also, the correlation between the percentages of oil in the embryo and in the seed-coat of the 3 types together is significant at 5% level. According to the results obtained in relation to the percentage in 28 varieties studied, it can be recommended, for breeding purposes, to work only with those varieties which belong to the medium and the large types of seeds.

Effect of brushwood transposition on the leaf litter arthropod fauna in a cerrado area

The results of ecological restoration techniques can be monitored through biological indicators of soil quality such as the leaf litter arthropod fauna. This study aimed to determine the immediate effect of brushwood transposition transferred from an area of native vegetation to a disturbed area, on the leaf litter arthropod fauna in a degraded cerrado area. The arthropod fauna of four areas was compared: a degraded area with signal grass, two experimental brushwood transposition areas, with and without castor oil plants, and an area of native cerrado. In total, 7,660 individuals belonging to 23 taxa were sampled. Acari and Collembola were the most abundant taxa in all studied areas, followed by Coleoptera, Diptera, Hemiptera, Hymenoptera, and Symphyla. The brushwood transposition area without castor oil plants had the lowest abundance and dominance and the highest diversity of all areas, providing evidence of changes in the soil community. Conversely, the results showed that the presence of castor oil plants hampered early succession, negatively affecting ecological restoration in this area.

Quantificação do linalol no óleo essencial da Aniba duckei Korstermans utilizando uma nova coluna capilar POLYH4-MD em Cromatografia Gasosa

In the present work a polyurethane polymer derived from castor oil was used as stationary phase for capillary gas chromatography. The polymer was obtained by reaction of hydroxylated compound and isocynate (NCO), forming urethane. Columns of 7 m x 0,25 mm were then coated with this stationary phase (film thickness of 0,25 µm) using static coating method. The Grob test was also performed. Samples of essential oil of the Aniba duckei Korstermans was then analysed in POLYH4-MD capillary column in order to evaluate its chromatographic perfomance. The linalool was found to be the major component and has been used as compound of departure for many important syntheses. Results show that the experimental columns give higher resolution and can be employed for analysis of essentials oils.

Epoxidação do óleo de mamona e derivados empregando o sistema catalítico VO(acac)2/TBHP

The alternative system VO(acac)2/TBHP was investigated for the epoxidation reaction of castor oil and its derivatives. Results of 88% of conversion, 73% of epoxidation and 82% of selectivity were obtained for the system containing 20% excess of TBHP and 1% of VO(acac)2 catalyst, during 3 h under toluene reflux. The product was characterized by GC/MS as methyl-cis-9, 10-epoxi, 12-hydroxystearate and quantitative ¹H NMR was used to calculate the data above. Preliminary results indicate that the heterogeneous system VO(acac)2 grafted on K10 clay can also promote epoxidation of castor oil.

Sintesis de poliuretanos a partir de polioles obtenidos a partir del aceite de higuerilla modificado por transesterificación con pentaeritritol

Castor oil was reacted by transesterification with various percentages in mass of pentaerythritol to obtain different esters of pentaerythritol. Alternatively, glycerol was also used instead of pentaerythritol for the same reaction in order to establish comparative reference products. The products of the reactions were characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy in order to detect and quantify (in terms of the molecular mass and structural information) the components of the products obtained. Analysis for hydroxyl value, acid value, viscosity and specific gravity were used to complete the characterization of the polyols obtained and also of the original castor oil. The polymer characterization was accomplished by tensile stress-strain tests, Shore A hardness, thermogravimetric analysis and chemical resistance to solvents.

Poliuretanos elastoméricos obtenidos a partir de aceite de ricino y almidón de yuca original y modificado con anhídrido propiónico: síntesis, propiedades fisicoquímicas y fisicomecánicas

Chemical modification of cassava starch was conducted through an acylation reaction by using pyridine and propionic anhydride to replace the functional groups of starch. Polyurethane elastomers were prepared using suspensions of the mixture obtained from castor oil and yucca starch that was modified by a propionic anhydride reaction. The suspensions were characterized by means of tests based on The Fourier Transform Infrared Spectroscopy and the Hydroxyl Index. The castor oil-AMP suspensions were used for the PU synthesis. The PUs were characterized by their physical-mechanical properties like tension- deformation and Shore A. hardness, thermal gravimetric analysis and swelling test. The density cross-linking of from swelling tests was determined by applying the Flory-Rehner equation.

Preparação e caracterização de suspensões coloidais de nanocarreadores lipídicos contendo resveratrol destinados à administração cutânea

Solid lipid nanoparticles (SLN), nanoemulsions (NE), and microemulsions (ME) were prepared by the hot solvent diffusion method, using tristearin or castor oil as oily phase, and soy lecithin and Solutol HS 15 as surfactants. Mean particle sizes ranged from 20 to 215 nm and negative zeta potentials were obtained for all nanocarriers. A HPLC method used to determine resveratrol was specific, linear, exact and precise. The entrapment efficiency was high for all formulations. However, resveratrol content was significantly varied among the lipid nanocarriers. Lipid nanocarrier containing hydrogels exhibiting pseudoplastic behavior were obtained after incorporation of hydroxyethylcellulose in the colloidal dispersions.

Adhesivos tipo poliuretano obtenidos a partir de aceite de ricino y almidón químicamente modificados

This study reports the preparation of polyurethane adhesives using polyols obtained from castor oil modified by a transesterification reaction with pentaerythritol and starch modified by glycosylation. The physical properties of the polyols such as hydroxyl value were determined and the infrared spectroscopic analysis of the polyols reported. The effect of varying the hydroxyl value in the polyols on physical properties of polyurethane coatings on wood and steel panels was determined. The characterization of polyurethane coatings carried out by IR spectroscopic analysis, scratch hardness resistance, impact resistance, lap shear strength, T-peel strength measurements, solvent resistance and chemical resistant determination were reported.

Síntese de poliuretanos modificados por óleo de mamona empregados em materiais energéticos

The aim of this work was to synthesize a polyurethane polymer matrix using castor oil as a polymer chain modifier, whose characteristics can be adjusted for use as a binder in the manufacture of energetic materials such as propellant and pyrotechnics for aerospace use. We attempted the partial substitution of hydroxyl-terminated polybutadiene (HTPB), a pre-polymer commonly used as a starting polyol in obtaining energetic matrix composites. Thermoanalytical techniques were employed to characterize the material based on castor oil and the unmodified HTPB. The results showed similar behaviors, confirming the possibility of their use as polymer matrix composites through the proposed adaptations.

Poliuretanos obtenidos a partir de aceite de higuerilla modificado y poli-isocianatos de lisina: síntesis, propiedades mecánicas y térmicas y degradación in vitro

Biodegradable polyurethanes (PUR) were prepared from polyols derived from castor oil by transesterification of pentaerythritol-modified castor oil and lysine polyisocyanates (LDI and LTI). The polyurethanes obtained were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA), and dynamic mechanical thermal analysis (DMTA). The mechanical behavior of the polyurethanes was measured by Shore A hardness and tensile testing (stress-strain curves). The biodegradable nature of the material was determined by contact angle, water absorption tests, and in vitro degradation in PBS solution. This study aims to examine the effect of the structure and functionality of diisocyanate on the mechanical properties and in vitro degradation of the material. The results were compared with homologous materials obtained from isophorone diisocyanate (IPDI) used in previous works. The objective was to evaluate candidate materials that can be potentially used in tissue engineering.

Antinociceptive effects of Cremophor EL orally administered to mice

Surfactants are frequently used to improve solubilization of lipophilic drugs. Cremophor EL (CrEL) is a polyoxyethylated castor oil surfactant used to solubilize water-insoluble drugs such as anesthetic, antineoplastic, immunosuppressive and analgesic drugs, vitamins and new synthetic compounds, including potential analgesics. The antinociceptive effect of CrEL (3.2, 6.4 and 10.6 g/kg, in 10 ml/kg body weight, by gavage) on the abdominal writhing response induced by intraperitoneal administration of acetic acid (0.8%, 10 ml/kg body weight) and on the tail immersion test was investigated in mice. Control animals received castor oil (10 ml/kg body weight) or saline (0.9% NaCl, 10 ml/kg body weight). CrEL reduced nociception in a dose-dependent manner in both tests. At 10.6 g/kg, CrEL caused antinociception similar to that induced by dipyrone (300 mg/kg, by gavage) in the abdominal writhing test, and antinociception similar to that induced by morphine (20 mg/kg, by gavage) in the tail immersion test. The effect of castor oil was similar to that of saline in both assays. These data indicate that the appropriate controls should be used when evaluating the effects of potential antinociceptive agents dissolved in CrEL.

Effect of (-)-∆9-tetrahydrocannabinoid on the hepatic redox state of mice

(-)-∆9-Tetrahydrocannabinol (∆9-THC), a psychoactive component of marijuana, has been reported to induce oxidative damage in vivo and in vitro. In this study, we administered ∆9-THC to healthy C57BL/6J mice aged 15 weeks in order to determine its effect on hepatic redox state. Mice were divided into 3 groups: ∆9-THC (N = 10), treated with 10 mg/kg body weight ∆9-THC daily; VCtrl (N = 10), treated with vehicle [1:1:18, cremophor EL® (polyoxyl 35 castor oil)/ethanol/saline]; Ctrl (N = 10), treated with saline. Animals were injected ip twice a day with 5 mg/kg body weight for 10 days. Lipid peroxidation, protein carbonylation and DNA oxidation were used as biomarkers of oxidative stress. The endogenous antioxidant defenses analyzed were glutathione (GSH) levels as well as enzyme activities of superoxide dismutase, catalase, glutathione S-transferase, glutathione reductase, and glutathione peroxidase (GPx) in liver homogenates. The levels of mRNA of the cannabinoid receptors CB1 and CB2 were also monitored. Treatment with ∆9-THC did not produce significant changes in oxidative stress markers or in mRNA levels of CB1 and CB2 receptors in the liver of mice, but attenuated the increase in the selenium-dependent GPx activity (Δ9-THC: 8%; VCtrl: 23% increase) and the GSH/oxidized GSH ratio (Δ9-THC: 61%; VCtrl: 96% increase), caused by treatment with the vehicle. Δ9-THC administration did not show any harmful effects on lipid peroxidation, protein carboxylation or DNA oxidation in the healthy liver of mice but attenuated unexpected effects produced by the vehicle containing ethanol/cremophor EL®.