The physico-chemical properties of the medium, and consequently the ultrasonic velocity and attenuation, are highly dependent on the sample temperature. The ultrasonic velocity decreases with increasing temperature in fats and oils (McClements, 1997). The influence of temperature on attenuation is scarcely reported in the literature. Figure 2 shows the variation of velocity and attenuation with the temperature for oil fried 2, 10 and 16 h. The ultrasonic velocity decreases linearly with temperature as reported by other authors (McClements, 1997; Benedito et al., 2001). The average slope of the linear relationships was -3,4 m s -1 ºC -1 , very close to that reported by McClements (1997) for liquid oils (-3,3 m s -1 ºC -1 ). The decrease of the attenuation with the temperature is probably due to the decrease of viscosity.
The evolution of temperature versus microwave treatment time is shown in Figure 1 for flours with 13% to 25% moisture contents. In the first 20 s of treatment the flours had got 59ºC and 72ºC, respectively. After 2 ½ min and 2 min (for 13 and 25% moisture) both flours attained a constant temperature around 95ºC and 97ºC, respectively, leading to a plateau value as found by other authors (Lewandowicz et al. 1997). Lewandowicz et al. (1997) reported that the plateau interval length increased with the rise in moisture content and also when the sample was introduced in sealed containers instead of open ones; the sealed beakers used were covered by these authors with a perforated polyethylene foil that probably allowed some water loss during heat treatment. As can be concluded from the temperature-time responses, all the attained plateau temperature values were always below 100ºC (presumably due to the ‘colling effect’ from water evaporation), with water acting as ‘protector’ of the flour constituents. This relatively low temperature probably explains the smaller changes in the physico-chemical properties of the heat-treated flours.
The reason for choosing the theme "Modern physico-chemical analysis of drinking water from Ceyranbatan reservoir" was to explore highly toxic heavy and other metals, which pose a threat to human health using the most modern equipment such as “ICP-MS” In addition, other important traces compounds in drinking water were also considered.
Wood properties are also affected by silvicultural practices (Gonçalves et al. 2004). A lower planting den- sity reduces competition for light, nutrients and water, thereby affecting the volume and density of the wood produced. Likewise, soil fertilization affects vessel frequency and fibre wall thickness, hence wood density (Lima et al. 2010). In addition, the forestry regime governs wood properties. According to Zobel and Buijtenen (2012), the physico-chemical properties of woods of the same age do not usually display any large differences between coppice and/or high forest management. However, Zbonak et al. (2007) found that coppice wood is less dense than that produced from a high forest. Many studies have been carried out on eucalyptus cop- picing, but mainly focusing on tree growth. Very few studies have analyzed wood properties with this type of management (Zbonak et al. 2007, Zobel and Buijtenen 2012). More specifically for E. robusta, studies involving high forest wood have mainly focused on physical and mechanical properties (Carvalho et al. 2016, Jiofack-Tafokou 2008) and not on the physico-chemical properties of coppice wood, yet properties such as density greatly influence charcoal quality (Gough et al. 1989).
Vernal pools are temporary wetlands result of the flooding of shallow basins when temperature is sufficiently warm for the growth of vegetation that has adapted and evolved under this especific conditions. The destruction of these ecosystems in Baja California is imminent, mostly by land development. Protection and conservation in Mexico is difficult because there is scarce information about their biology, although there is some foreing information without impact in our country, about their rare and endemic plants. We compiled information and search for eleven vernal pool´s endemic and rare flora in Northwestern Baja Californa, Mexico, studied their actual ocurrence and the distribution of nine plant species and their relation with physico-chemical soil properties: pH, Cation Capacity Interchange, Electric Conductivity, Organic Matter and Nutrients. We sampled four areas: Mesa de Jesús María, Valle de las Palmas, Valle de Guadalupe, and Colonet. For the entire region, the rare and endemics are: Centromadia perennis, Deschampsia dantonoides, Eryngium aristulatum var. parishii, Myosurus minimus ssp. apus, Navarretia fossalis, Orcuttia californica, Pogogyne sp. (in Valle de las Palmas), Plagiobothriys bracteatus, and P. leptocladus. Historical data and those obtained in this study suggest differences between coastal and inland localities, according to the composition of rare and endemic species, in need of further study of other localities. Relying previous studies C. perennis and Pogogyne sp. nov . showed a highly restricted distribution. It was determined that there is no direct correlation between the distribution of species and soil properties, so we suggest more attention to the biology of each species and habitat historical aspects.
analyzed for chemical, thermal and functional properties as well as proximate analysis, organic elemental analysis, FT-IR, thermogravimetric, DSC, monosaccharide determination, solubility, rheology and emulsifying and foaming properties. Finally, some applications of the mucilage in the food industry were studied. Firstly, the mucilage was used to produce edible films and also a dairy dessert was produced where the commercial stabilizer was totally replaced with the mucilage from chia seeds. Edible films were obtained using a blend of the mucilage and whey protein concentrate in proportions 1:3 and 1:4 at pH 7 and 10 using glycerol as plasticizer. Transmission electron microscopy was used to investigate each dispersion from the previously formed film and each edible film was also observed by scanning electron microscopy while physical properties, color, opacity, moisture content, solubility, water vapour barrier and mechanical properties, were analyzed for. Finally, a dairy dessert was formulated using a commercial formula and subsequently was subjected to sensory evaluation with triangular and preference test, rheological characterization, syneresis, color and viscosity.
From this perspective, the Agüera is a stream where geology, topography, climate and human activities interact to produce broad spatial differences in a relatively small area. Temporal variability is also important, but at some scales more than at some others. Seasonal variations are relatively small as a result of the mild climate, but floods can occur at any time of the year, affecting both the physico-chemical characteristics of the water and the benthic communities, and making the Agüera stream an unpredictable environment. Harshness, variability, heterogeneity and predictability are key factors of the habitat, that provides the templet for ecological strategies in such a way that organisms adapt their life hitories to optimise their reproductive sucess (S OUTHWOOD , 1977; T OWNSEND et al., 1997). In general, invertebrates adapt by adjusting the number of generations per year and the timing of reproduction to the local conditions (G ILLER & M ALMQVIST , 1998). Unpredictable habitats
In this work, the influence of copper on the structural and catalytic properties of the samples was studied. The precursors, the mixed oxides and the samples reduced have been characterized by different physico-chemical methods, such as X-ray powdered diffraction (XRD), infrared (FT- IR), X-ray photoelectron spectroscopy (XPS), diffuse reflectance UV–vis (DR), thermogravimetric analysis (TGA), differential thermal analysis (DTA) and determina- tion of specific surface area.
Teak wood grown in Brazil has shorter cutting cycles when compared to its pays of origin due to the favorable edaphoclimatic conditions and silvicultural treatments; however, the juvenile wood exhibits a high proportion of sapwood, which has physical, chemical and aesthetic properties (color and design) quite different from heartwood. Teak heartwood has a good dimensional stability and high natural durability due to the presence of some substances such as caoutchouc, a latex responsible for the resistance to water absorption (Yamamoto et al. 1998); tectoquinone, 2-hydroxymethyl anthraquinone and lapachol, preservatives of phenolic nature present in the wood cells (Niamké et al. 2011). Teak sapwood exhibits light color, lower extractive content and low durability. Heat treatments allow to standardize the color of teak pieces containing heartwood/sapwood (Lopes et al. 2014) and in this way add value to the final product. Heat treatments cause physico-chemical modification at different levels depending on the characteristics of the material, therefore studies on the heat-treated sapwood and heartwood will contribute to a better understanding about the wettability of the surface of the heat- treated teak wood.
In order to check the stability of the catalyst and its resistance against deactivation phenomena, a long-time on stream experiment was carried out, comprising 260 hours of continuous operation. Figure 7 depicts the FAME yield results monitored during the overall experiment. Results confirm that particulate Zr-SBA-15 material is a quite robust and active catalyst in biodiesel production form waste cooking oil, since no evidence of catalytic deactivation is detected during the whole experiment. On average, the substrate stream is converted to provide 96% of FAME yield, which is sustained during the overall catalytic text. After time of stream, the agglomerated catalyst was recovered and without any treatment was analyzed to check the integrity of the physicochemical properties. Unless for the textural properties, the physico-chemical properties obtained by the characterization of the used catalyst (Table 3), are quite close to those obtained for the fresh particulate material, confirming the good stability of this catalyst. Mass zirconium loading of 7.2 % and acid capacity of 0.171 mmol H + per gram was obtained for the used catalyst which evidence that metal content and acid sites concentration of the Zr-SBA-15 catalyst were preserved after the catalytic cycle. In the case of the textural properties, the differences found between the fresh and the used particulate catalysts were ascribed to some loss in the microporous fraction of the pelletized material. This fraction of the porous structure of the SBA-15 materials does not play any important role in the conversion of bulky substrates such as triglycerides, and thus, this variation between the fresh and the used samples does not affect the catalytic performance of the pelletized Zr-SBA-15 material.
Water quality parameters and phyto- plankton assemblage: The phytoplankton assemblage of Oyun reservoir shows the res- ervoir to be eutrophic and its fluctuation is in response to seasonal concentration of nutrients, grazing pressure by biotic organisms and the reservoir hydrology. Nuisance conditions asso- ciated with high phytoplankton diversity and productivity were absent from the reservoir probably due to its shallow depth and high mixing volume. This made the water quality to be good in relation to phytoplankton composi- tion. The water quality of Oyun reservoir as assessed from the physico-chemical proper- ties compared well with the ranges found in other Nigerian reservoirs (Kemdirim 1990, Akinbuwa 1992). It also fell within the range of allowable limits recognized by WHO (1997) and NIS (2007).
Abstract: Soil dehydrogenase activity is a good indicator of overall microbial activity in soil, and it can serve as a good indicator of soil condition. However, seasonal changes in soil moisture content may have an effect on soil dehydrogenase activity, making an accurate assessment of soil condition difficult. In this study, we attempted to determine the significance of soil dehydrogenase activity for assessing soil condition, and we attempted to find a way to account for the influence of soil moisture content on soil dehydrogenase activity. Soils were sampled in dry evergreen forest (original vegetation), bare ground (severely degraded) and Acacia plantation plots established on bare ground in 1986 and 1987 in Sakaerat, Thailand. Soil physico-chemical characteristics and dehydrogenase activity in the Acacia plantation soil had few differences from those in the evergreen forest soil. Soil dehydrogenase activity varied significantly between the bare ground and the forests regardless of the season (wet or dry), while the season did not produce a significant variation in soil dehydrogenase activity, as determined by repeated measures analysis of variance (p=0.077). The physico-chemical data provided the first principal component as a good measure of soil fertility. Values of soil dehydrogenase activity significantly cor- related to scores of the soil samples of the first principal component (R=0.787, p<0.001). We found that soil dehydrogenase activity is a useful indicator of the extent of soil degradation and the rehabilitative effects of reforestation in this part of Thailand. Rev. Biol. Trop. 57 (1-2): 223-234. Epub 2009 June 30.
The greatest growth of inhibition rate of P. subcapitata was present in the bioassay of the sample point from Capiza, seeing that the physico-chemical parameters pH, TSS (total suspended solids), Manganese and Iron surpass the EQS (Peruvian National standards of environment) for water (Table 1), with the regression and correlation analysis, a relation highly significant (F= 65.562; P < 0.01) was determined between the physicochemical parameters pH, Mn, TSS and the growth of inhibition percentage of P. subcapitata. The relation between the variables is high, explained by the Pearson correlation coefficient (r=0.98).
This constitutes a biodiversity hotspot with high levels of biodiversity and endemism; unfortunately, is also a poorly known area, especially on its microbial diversity. In this study, we assessed cultivable soil bacterial diversity and distribution from lowlands to highlands (34 to 3 990m.a.s.l.). Soil physico-chemical parameters and forest types across the different altitudes were characterized and correlated with bacterial distribution and diversity. Microbes from the soil samples were grown in Nutrient, Muller Hinton and Luria-Bertani agar plates and were initially characterized using biochemical methods. Parameters like dehydrogenase and urease activi- ties, temperature, moisture content, pH, carbon content, bulk density of the sampled soil were measured for each site. Representative isolates were also subjected to 16S rDNA sequence analysis. A total of 155 cultivable bacte- rial isolates were characterized which were analyzed for richness, evenness and diversity indices. The tropical and sub-tropical forests supported higher bacterial diversity compared to temperate pine, temperate conifer, and sub-alpine rhododendron forests. The 16S rRNA phylogenetic analysis revealed that Firmicutes was the most common group followed by Proteobacteria and Bacteroidetes. Species belonging to the genera Bacillus and Pseudomonas were the most abundant. Bacterial CFU showed positive but insignificant correlation with soil parameters like pH (r=0.208), soil temperature (r=0.303), ambient temperature (r=0.443), soil carbon content (r=0.525), soil bulk density (r=0.268), soil urease (r=0.549) and soil dehydrogenase (r=0.492). Altitude (r=- 0.561) and soil moisture content (r=-0.051) showed negative correlation. Altitudinal gradient along with the veg- etation and soil physico-chemical parameters were found to influence bacterial diversity and distribution. This study points out that this is a biome with a vast reservoir of bacteria which decrease with increasing altitudes, and highlights the microbiological importance of the poorly studied Eastern Himalayan range, justifying efforts to explore the prevalence of novel species in the biome. Rev. Biol. Trop. 61 (1): 467-490. Epub 2013 March 01. Key words: cultivable bacteria, Eastern Himalyan range, tropical region, altitude, 16S rRNA, diversity indices.