Analysis of volatile components by direct injection of real-life samples by using a programmed-temperature vaporizer

A Chromatographic method is presented which allows the analysis of the volatile components of real-life samples without requiring the previous isolation and concentration of the compounds of interest. A programmed-temperature vaporizer (PTV) is used to enable the direct injection of the sample. A comparison of the proposed method with one involving a liquid-liquid extraction of the sample is also included.     

Solar light induced removal of arsenic from contaminated groundwater: the interplay of solar energy and chemical variables

The removal of arsenic by solar oxidation in individual units (SORAS) is currently being explored as a possible economic and simple technology to treat groundwater in Bangladesh and India. Hydroarsenicism affects also large regions of America, especially Argentina, Chile, Mexico and Peru. In this paper, the efficiency of arsenic removal by solar oxidation coupled with precipitation of iron (hydr)oxide, was assessed under various experimental conditions, both on samples of synthetic water and of groundwater of the province of Tucumán (Argentina). The results demonstrate that the underlying chemistry is very complex, and the efficiency is affected often in unpredictable ways by changes in the chemical matrix, or by changes in the operative conditions. Oxides generated from ferrous salts are more efficient than solids formed by hydrolysis of Fe(III); alkalinity contents (bicarbonate) is also important to permit the adequate precipitation. Addition of small amounts of citric acid (lemon juice) is beneficial, but at larger concentrations the effect is negative, probably because of interference in the formation of the solid. The effect of solar irradiation is variable, depending on the other experimental conditions. Although it is possible to remove As partially without solar irradiation under certain special conditions, a procedure versatile enough to cope with waters of different compositions must be based in the use of solar energy. Light plays the role of accelerating the oxidation of As(III) to As(V), and also affects the nature of the solid and, hence, its sorptive properties. The rationale of the effect of light is therefore appreciably more complex than in the case of heterogeneous photocatalysis with TiO₂.     

Induced expression of bacterial β-glucosidase activity in saccharomyces

The bglA gene which encodes a β-glucosidase from Bacillus polymyxa, has been expressed in Saccharomyces cerevisiae under control of the yeast CYC-GAL promoter. Strains have been constructed which carry the gene in different locations: in a multicopy plasmid, a single integration at the URA3 locus, or multiple integrations at the RDN1 locus. Integrative transformation at RDN1 yielded genetically stable clones with a high level of β-glucosidase activity. Coordinated overexpression of the GAL4 inducer protein further increased the level of enzyme activity, although eventually caused the lysis of the cultures. Diploid, triploid and tetraploid strains derived from the transformants with multiple integrations were constructed and expression of β-glucosidase activity in different conditions of growth was assayed. While per-cell activity increased with ploidy, specific activity was about the same in strains of equivalent genotype regardless of ploidy. Genetically stable and regulated expression in Saccharomyces of β-glucosidase activity is interesting for the development of strains able to ferment β-glycosidic sugars (i.e. cellobiose and lactose). From another point of view, the bglA product proved to be a convenient reporter enzyme to monitor heterologous gene expression.     

Microcutting culture and morpho-physiological changes during acclimation in two Lycium chilense cytotypes.

Lycium chilense, a deciduous perennial shrub, is one of the endangered native species of Patagonia due to sheep overgrazing. Chances of recolonization by seeds are scarce due to the limited density of propagules in the soil and very specific requirements for germination. The objective was to develop an in vitro propagation protocol that would help to perform reestablishment of this species in degraded areas of the Patagonian steppe. Seeds came from two provenances with different somatic number due to differences in ploidy level. Defoliated microcuttings were planted in test tubes with different growing media and taken to a growth chamber. Rooting percentage did not differ between origins, but higher values were encountered for medium without hormones. Subcultures increased significantly rooting percentage and reduced time to rooting. The leaves from micropropagated plants were thinner, did not exhibit hairs, and had poorly developed palisade parenchyma and less epicuticular waxes. In vitro leaves had lower stomatal density and their stomata were less functional when compared to acclimated leaves. A repopulation program of Lycium chilense based on microcutting culture, specially using subcultures, is feasible.     

Complex structure and catalytic hydrogen ion reduction in Ni (II)-glutathione system

Polarographic studies on the reduction of hydrogen ions in the presence of Ni(II)-glutathione complexes revealed for alkaline solutions two catalytic waves. The catalytic reduction of hydrogen occurs only in the presence of square planar complexes which seem to be responsible for the catalysis. Besides the planar structure the metal-sulphur bond is necessary for the latter process.     

New Spectrophotometric System to Segregate Tissues in Mandarin Fruit

The knowledge of the electrical properties of the fruit tissues and their relation with the structural and compositional properties opens an endless number of opportunities in the development and design of industrial equipment for quality and process control. Nowadays, one of the main industrial issues is the detection of seeds inside the fruit, which could be possible with an electrical study of each tissue as a first step of the development of non-destructive sensors. In this context, a deep study of the dielectric properties of mandarin fruit tissues, coupled with a _w, X _w, pH, maturity index, cryo-SEM, and optical measurements, was performed. Dielectric properties were studied in radiofrequency and microwave ranges. α-, β-, and γ-dispersions and their relaxation parameters were obtained, described, and related to the chemical parameters. Finally, a tool, based on the relaxation dielectric constant in γ-dispersion able to determine the moisture content of the mandarin fruit tissues, has been developed.     

Cooperative learning strategies to teach nutrition to geriatric nursing staff

The objective of this study was to test the hypothesis that cooperative learning strategies will help to increase nutrition knowledge of nurses and nursing assistants caring for the elderly in different institutional communities of the Basque Country, Spain. The target population was a sample of volunteers, 16 nurses and 28 nursing assistants. Training consisted of 12 nutrition education sessions using cooperative strategies conducted over a period of 3 consecutive weeks. The assessment instruments included two pretest and two posttest questionnaires with questions selected in multiple-choice format. The first questionnaire was about general knowledge of applied nutrition (0-88 point scale) and the second one on geriatric nutrition knowledge (0-18 point scale). Data were analyzed using SPSS vs. 11.0. The outcomes indicated a significant increase in general nutrition knowledge (difference between the pre- and post-test mean score: 14.5+/-10.1; P<0.001) and in geriatric nutrition knowledge for all participants (difference between the pre- and post-test mean score: 4.6+/-4.6; P<0.001). So the results indicated that cooperative learning strategies could improve the nutrition knowledge of nursing staff. Additionally, the results of this study provide direction to continuing nutrition education program planners regarding appropriate content and methodology for programs.     

Modeling of the internal fields distribution in human inner hearing system exposed to 900 and 1800 MHz

This paper investigates the internal electric and magnetic field distribution and the specific absorption rate (SAR) values in a magnetic resonance imaging-based model of the inner hearing system exposed to 900 and 1800 MHz. The internal fields distributions were calculated using the Finite Integration Technique. The estimation of the field values was evaluated along lines passing through that target organ, specifically from the vestibular to the cochlear region and from the apex to the base of the cochlea. The specific findings are: 1) higher internal fields strength and SAR value in the vestibular region rather than in the auditory region, especially for the inner ear closer to the external source; 2) higher internal fields strength in the basal and apical region of the cochlea than in the middle one; 3) local differences in the internal fields distribution and SAR value, comparing the head models including or not the inner auditory system model; 4) results' variability evaluated by changing the head-source mutual position and the dielectric properties of the inner hearing system.     

面向永恒的建筑

每座建筑的位置一般不会改变,改变的是它所经历的沧海桑田。无论是应用一套方案复制多个建筑,还是实现建筑的多样化,只有建筑方案的存在是短暂的,而建筑本身往往会长存于世,见证着它周围社会及文化的变迁。这意味着建筑必须面对时间的流逝做出抉择——何时该随之改变,何时该保持不变,何时该果断谢幕。一些建筑（以及更多的城市开发区）往往要比它们的建筑师的寿命更长,因而对建筑而言,未来不过是另一个现在的翻版。此外,原有的（文化）基础也是建筑所必须面对的。或被动或主动,建筑总是将自己置身于艰难的位置,要面对过去的一切。而最终,使用者检验建筑要花费的正是时间,正是从建筑竣工的那一刻起,它也在以某种方式控制着自己发展的节奏。那么,我们能否设计时间呢？本文将通过横向剖析,透过与时间概念的关系,来审视新近的西班牙建筑。