Rheological Characterization of Hydrophylic Gels

Rheological characteristics of gels were studied, with the focus on their use as a cosmetic base. Some ideal characteristics can be predicted by the rheological characterization, such as the performance, with easy application and without dripping or forming lumps and bubbles. Moreover, it is possible to detect signs of physical instability. The gels were prepared with sodium carboxymethyl cellulose 3% and 5%, with Carbopol 940 (INCI: Carbomer) and with Carbopol Ultrez (INCI: Acrylates/C10-30 alkyl acrylate crosspolymer). The tests performed were yield stress, stress sweep and creep and recovery. The gel with 3% of sodium carboxymethyl cellulose presented the most appropriated behavior and can be indicated as the most suitable cosmetic base.

Rheological Analysis of Water Clay Compositions in Order to Investigate Mudflows Developing in Canals

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

Chemical communication in Apis mellifera: Temporal modulation of alarm behaviors

The effect of pheromones and their chemical analogues in honeybee alarm behaviors was studied in observation boxes. Defensive behaviors, as follows: a) attraction to scent source, b) elevation of wings in 'V', c) abdomen elevation, d) abdomen elevation and pumping and e) first leg pair elevation had been temporarily registered when the following compounds were presented: isoamyl alcohol, octyl alcohol, benzyl alcohol, n-butyl acetate, n-octyl acetate, isopentyl acetate, benzyl acetate and 2-heptanone. The results were as follows: 1. the bees elicited some characteristic behaviors when chemical alarm messages were presented, 2. agression (stinging) was not completed with any compound tested, probably because there was not a target (visual stimulus), 3. in all situations the attraction to scent source was low, 4. all the behaviors were elicited in a temporarily different way, 5. the compounds that elicited stronger responses and a greater number of the investigated behaviors were: isopentyl acetate, 2-heptanone, octyl acetate and n-octyl alcohol. In all situations, the first behavior response (and the most intense one) was the elevation and pumping the abdomen. This suggests that the chemical message was promptly recognized and then transmitted to each worker. So, the results obtained in the present work, suggest that chemical alarm messages may be recognized by different mechanisms of neural integration.

Rheological properties of tin oxide suspensions

The rheological properties of tin oxide slurries were studied experimentally and theoretically. The deflocculants used were ammonium polyacrilate (PAA) and the copolymer poly(vinyl butyral-co-vinyl alcohol-co-vinyl acetate) (PVB-PVA-PVAc), in water and ethanol, respectively. The amount of deflocculant was optimized for different solid contents by means of viscosity measurements. In spite of the high stability of PVB-dispersed slurries, a high solid concentration was not obtained. On the other hand, a slurry with a 56.4 vol.% of solids was attained when PAA was used. A theoretical study of the adsorption of PAA in its dissociated (basic solution) and non-dissociated (acidic solution) forms on SnO 2 (110) is presented. This analysis was made by means of the PM3 method using a large cluster Sn 15O 28 for the surface model. The calculated adsorption energy is larger for the ionized PAA than for the non-ionized form, indicating that alkaline slurries favor PAA adsorption on the SnO 2 surface. © 2002 Elsevier Science Ltd. All rights reserved.

Influence of carrageenan and total solids content on the rheological properties of lactic beverage made with yogurt and whey

The purpose of this work was to study the influence of carrageenan level (X 1) and total solids content of yogurt/whey mixture (X 2) on starter culture fermentation time, physicochetnical properties (pH, fat and total solids contents) and rheological characteristics of lactic beverages using response surface methodology. The physicochemical characteristics of the lactic beverages were similar to those of commercial products. All beverages showed non-Newtonian fluid behavior with thixotropy and yield stress. The total solids content of the lactic beverages had a greater influence on the rheological behavior of these products than the carrageenan level. Wide ranges of consistency measurements were observed by varying the stabilizer level and total solids content.

Morphological, mechanical and rheological properties of nylon 6/acrylonitrile-butadiene-styrene blends compatibilized with MMA/MA copolymers

The morphological, mechanical and rheological properties of nylon 6/acrylonitrile-butadiene-styrene blends compatibilized with MMA-MA [poly(methyl methacrylate-comaleic anhydride)] copolymers were studied. A twin screw extruder was used for melt-blended the polymers and the injection moulding process was used to mold the samples. The main focus was on nylon 6/ ABS blends compatibilized with one MMA-MA copolymer. This copolymer has PMMA segments that appear to be miscible with the styrene-acrylonitrile (SAN) phase of ABS and the anhydride groups can react with amine end groups of the nylon 6 (Ny6) to form graft copolymers at the interface between Ny6 and ABS rich phases. Tensile and impact and morphological properties were enhanced by the incorporation of this copolymer. Transmission electron microscopy (TEM) observations revealed that the ABS domains are finely dispersed in nylon 6 matrix and led to the lowest ductile-brittle transition temperatures and highest impact properties. It can be concluded that the MMA-MA copolymer is an efficient alternative for the reactive compatibilization and can be used as a compatibilizer for nylon 6/ABS blends.© 2003 Kluwer Academic Publishers.

Effect of lithium doping on the evolution of rheological and structural properties during gelation of siloxane-poly(oxypropylene) nanocomposites

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

Simultaneous effects of total solids content, milk base, heat treatment temperature and sample temperature on the rheological properties of plain stirred yogurt

Response surface methodology was used to establish a relationship between total solids content, milk base, heat treatment temperature, and sample temperature, and consistency index, flow behaviour index, and apparent viscosity of plain stirred yogurts. Statistical treatments resulted in developments of mathematical models. All samples presented shear thinning fluid behaviour. The increase of the content of total solids (9.3-22.7 %) and milk base heat treatment temperature (81.6-98.4°C) resulted in a significant increase in consistency index and a decrease in flow behaviour index. Increase in the sample temperature (1.6-18.4°C) caused a decrease in consistency index and increase in flow behaviour index. Apparent viscosity was directly related to the content of total solids. Rheological properties of yogurt were highly dependent on the content of total solids in milk.

Prevalence and associated factors for suicidal ideation and behaviors in obsessive-compulsive disorder

Introduction: Patients with obsessive-compulsive disorder (OCD) have historically been considered at low risk for suicide, but recent studies are controversial. Objective: To study the prevalence of suicidal thoughts and attempts in OCD patients and to compare those with and without suicidality according to demographic and clinical variables. Methods: Fifty outpatients with primary OCD (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition) from a Brazilian public university were evaluated. The Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) was used to assess OCD severity, the Beck Depression Inventory to evaluate depressive symptoms and the Alcohol Use Disorders Identification Test to assess alcohol problems. Results: All patients had obsessions and compulsions, 64% a chronic fluctuating course and 62% a minimum Y-BOCS score of 16. Half of the patients presented relevant depressive symptoms, but only three had a history of alcohol problems. Seventy percent reported having already thought that life was not worth living, 56% had wished to be dead, 46% had suicidal ideation, 20% had made suicidal plans, and 10% had already attempted suicide. Current suicidal ideation occurred in 14% of the sample and was significantly associated with a Y-BOCS score ≥16. Previous suicidal thoughts were associated with a Beck Depression Inventory score ≥19. Conclusion: Suicidally has been underestimated in OCD and should be investigated in every patient, so that appropriate preventive measures can be taken.

Effects of the density, aviary type, breed, and age on the behaviors of laying hens kept in cages

An experiment was carried out in order to investigate the behaviors of laying hens due to the environmental factors of: density inside of the cage, aviary type, breed, and age. The experiment was configured as a factorial 4x2x2x2 study, with treatments being four different ages, two different breeds, two different cage densities, and two different aviaries. The birds' behaviors were recorded using video cameras installed in the cages, using samples of 15 minutes recorded from 12 PM to 4 PM. The observed behaviors, frequency and duration of behaviors (measured in seconds) were identified and noted related to each bird. The study was initiated in March 2007, during four non-consecutive weeks. The observed behaviors were: opening wings, stretching, threatening, ruffling feathers, drinking water, aggressive pecking, eating, running, lying down, stretching head out of the cage, preening, mounting, prostrating, and doing nothing (inactivity). Due to the non-normality of the data recorded, the Kruskal-Wallis statistical test of the MINITAB Statistical Software® was used to compare the medians of the variables. For breed factor, only the durations of the eating presented significant differences (p-value< 0.05). For cage density, there was a significant median difference (p-value< 0.05) for almost all behaviors observed. The average length of time of behaviors was higher for the lowest cage density. However, the frequency of behaviors was lmerfor the lowest cage density. The frequency of the behaviors to preen feathers, to lie down, to drink water and to stretch the head were higher in the aviary, where the groups of birds were smaller. The observed behaviors were particularly affected by experimental factors cage density, and aviary type, which directly affects the available space for each bird.

The thermal, rheological and structural properties of cassava starch granules modified with hydrochloric acid at different temperatures

Starch is arguably one of the most actively investigated biopolymer in the world. In this study, the native (untreated) cassava starch granules (Manihot esculenta, Crantz) were hydrolyzed by standard hydrochloric acid solution at different temperatures (30 °C and 50 °C) and the hydrolytic transformations were investigated by the following techniques: simultaneous thermogravimetry-differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC), as well as non-contact atomic force microscopy (NC-AFM), X-ray diffraction (XRD) powder patterns, and rapid viscoamylographic analysis (RVA). After the treatment with hydrochloric acid at different temperatures, the thermal stability, a gradual loss of pasting properties (viscosity), alterations in the gelatinization enthalpy (ΔHgel), were observed. The use of NC-AFM and XRD allowed the observation of the surface morphology and topography of the starch granules and changes in crystallinity of the granules, respectively. © 2012 Elsevier B.V. All rights reserved.

Determination of the Real Influence of the Addition of Four Thickening Agents in Creams Using Rheological Measurements

This study aimed to characterize different emulsions obtained by the addition of four thickening agents, using rheological measurements, beyond analyzing the emulsions by polarized light microscopy looking for liquid crystals on them. The addition of these four thickening agents did not modify the base emulsion rheology, only an improvement in the sensory of the formulation was verified. The polarized light microscopy showed the formation of liquid crystalline structures in all the formulations, thus, the thickening agents did not influence in this parameter too. However, the emulsions could be considered appropriated for cosmetic purposes, probably being highly physically stable. © 2013 Copyright Taylor and Francis Group, LLC.

Effect of Various Thickening Agents on the Rheological Properties of Oil-in-Water Emulsions Containing Nonionic Emulsifier

The knowledge of rheological characteristics can indicate the emulsions properties, thus, nowadays rheology is used in the cosmetic and pharmaceutical industries, even to study the influence of rheological additives on them. Ten emulsions were prepared with 5% and 10% of nonionic emulsifier. Two of them were used as controls while in the others were added thickening agents. Rheological analyses were performed. The results showed that all emulsions are non-Newtonian, thixotropics and viscoelastics fluids. The thickening agents could modify the rheological characteristics of the emulsions and knowing the influence of them is easy to adopt one to reach the desirable performance. © 2013 Copyright Taylor and Francis Group, LLC.

Predation-risk effects of predator identity on the foraging behaviors of frugivorous bats

Predators directly and indirectly affect the density and the behavior of prey. These effects may potentially cascade down to lower trophic levels. In this study, we tested the effects of predator calls (playbacks of bird vocalizations: Tyto alba, Speotyto cunicularia, and Vanellus chilensis), predator visual stimuli (stuffed birds) and interactions of visual and auditory cues, on the behavior of frugivore phyllostomid bats in the field. In addition, we tested if the effects of predation risk cascade down to other trophic levels by measuring rates of seed dispersal of the tree Muntingia calabura. Using video recording, we found that bats significantly decreased the foraging frequency on trees when a visual cue of T. alba was present. However, no stimuli of potential predatory birds, including vocalization of T. alba, affected bat foraging frequency. There was a change in bat behavior during 7 min, but then their frequency of activity gradually increased. Consequently, the presence of T. alba decreased by up to ten times the rate of seed removal. These results indicate that risk sensitivity of frugivorous phyllostomid bats depends on predator identity and presence. Among the predators used in this study, only T. alba is an effective bat predator in the Neotropics. Sound stimuli of T. alba seem not to be a cue of predation risk, possibly because their vocalizations are used only for intraspecific communication. This study emphasizes the importance of evaluating different predator stimuli on the behavior of vertebrates, as well as the effects of these stimuli on trait-mediated trophic cascades. © 2013 Springer-Verlag Berlin Heidelberg.

The who start study suicidal behaviors across different areas of the world

Background: The World Health Organization (WHO) study entitled Suicide Trends in At-Risk Territories (START) is an international multisite initiative that aims to stimulate suicide research and prevention across different areas of the globe. A central component of the study is the development of registration systems for fatal and nonfatal suicidal behaviors. Aims: This paper provides an overview of the data collected on suicidal behaviors from the participating locations in the START study. Method: Descriptive statistics on the data are presented in terms of age, sex, and method. Results: Agreater proportion of suicide deaths occurred among males. In all areas except the Philippines more females than males engaged in nonfatal suicidal behaviors. Compared to Australia, Italy, New Zealand, the Philippines, and Hong Kong SAR, in the Pacific Islands suicide most often occurs in younger age groups. Results indicate notable variations between countries in choice of method. A greater proportion of suicides occurred by hanging in Pacific Islands, while inhalation of carbon monoxide, use of firearms, ingestion of chemicals and poisons, and drug overdose were the most frequent methods of choice in other areas. Conclusion: The information drawn from this study demonstrates the enormous variation in suicidal behavior across the areas involved in the START Study. Further research is needed to assess the reliability of the established data-recording systems for suicidal behaviors. The baseline data established in START may allow the development of suicide prevention initiatives sensitive to variation in the profile of suicide across different locations. © 2013 Hogrefe Publishing.