AN INVESTIGATION OF THE EFFECT OF FORMALDEHYDE SPECIES ON ENVIRONMENTAL MEASUREMENT METHODS UNDER AMBIENT CONDITIONS

Species variations in formaldehyde solutions and gases were investigated by means of infrared spectral analysis. Double beam infrared spectrometry in conjunction with sodium chloride wafer technique and solvent compensation technique were employed. Formaldehyde species in various solutions were investigated. Formalin 37% was stable for many months. Refrigeration had no effects on its stability. Spectral changes were detected in 1000 ppm formaldehyde solutions. The absorbances of very diluted solutions up to 100 ppm were lower than the detection limit of the instruments. Solvent compensation improved resolution, but was associated with an observed lack of repeatability. Formaldehyde species in animal chambers containing animals and in mobile home air were analyzed with the infrared spectrophotometer equipped with a 10 cm gas cell. Spectra were not different from the spectrum of clean air. A portable single beam infrared spectrometer with a 20 meter pathlength was used for reinvestigation. Indoor formaldehyde could not be detected in the spectral; conversely, an absorption peak at 3.58 microns was found in the spectra of 3 and 15 ppm formaldehyde gas in animal chambers. This peak did not appear in the spectrum of the control chamber. Because of concerns over measurement bias among various analytical methods for formaldehyde, side-by-side comparisons were conducted in both laboratory and field measurements. The chromotropic acid method with water and 1% sodium bisulfite as collection media, the pararosaniline method, and a single beam infrared spectrometer were compared. Measurement bias was elucidated and the extent of the effects of temperature and humidity was also determined. The problems associated with related methods were discussed. ^

Diagenetic alteration of organic matter in DSDP Leg 57 Holes

I analyzed Leg 57 sediments organogeochemically and spectroscopically. Organic carbon and extractable organic matter prevail from the Pliocene to the Miocene. Humic acids occur widely from the Pleistocene to the lower Miocene and one portion of the Oligocene. The absence of humic acids in Oligocene and Cretaceous samples suggests that humic acids had changed to kerogen. Visible spectroscopic data reveal that humic acids in this study have a low degree of condensed aromatic-ring system, which is a feature of anaerobic conditions during deposition, and that chlorophyll derivatives that had at first combined with humic acids moved to the solvent- soluble fraction during diagenesis. The elemental compositions of humic acids show high H/C and O/C ratios, which seem appropriate to a stage before transformation to kerogen. The relation between the linewidths and g-values on the electron spin resonance data indicates that the free radicals in humic acids are quite different from those in kerogen. The low spin concentrations of kerogen and the yields of humic acids up to the lower Miocene demonstrate that organic matter in these sediments is immature. The foregoing indicate the necessity to isolate humic acids even in ancient rocks in the study of kerogen.

Healthy aging : Free time of adults

El trabajo que aquí se presenta surge de la necesidad de conceptualizar y profundizar sobre el uso productivo del tiempo libre de las personas adultas mayores. Se llevará a cabo una aproximación teórica sobre las diferentes concepciones de tiempo libre y ocio como dimensiones interdisciplinarias que involucran elementos referidos al entorno en donde personas y comunidades buscan integrarse en un tiempo y espacio determinado

Healthy aging : Free time of adults

El trabajo que aquí se presenta surge de la necesidad de conceptualizar y profundizar sobre el uso productivo del tiempo libre de las personas adultas mayores. Se llevará a cabo una aproximación teórica sobre las diferentes concepciones de tiempo libre y ocio como dimensiones interdisciplinarias que involucran elementos referidos al entorno en donde personas y comunidades buscan integrarse en un tiempo y espacio determinado

Healthy aging : Free time of adults

El trabajo que aquí se presenta surge de la necesidad de conceptualizar y profundizar sobre el uso productivo del tiempo libre de las personas adultas mayores. Se llevará a cabo una aproximación teórica sobre las diferentes concepciones de tiempo libre y ocio como dimensiones interdisciplinarias que involucran elementos referidos al entorno en donde personas y comunidades buscan integrarse en un tiempo y espacio determinado

Volume of natural gas within gas-hydrate and free-gas occurrences in ODP Leg 164 sites

Leg 164 of the Ocean Drilling Program was designed to investigate the occurrence of gas hydrate in the sedimentary section beneath the Blake Ridge on the southeastern continental margin of North America. Sites 994, 995, and 997 were drilled on the Blake Ridge to refine our understanding of the in situ characteristics of natural gas hydrate. Because gas hydrate is unstable at surface pressure and temperature conditions, a major emphasis was placed on the downhole logging program to determine the in situ physical properties of the gas hydrate-bearing sediments. Downhole logging tool strings deployed on Leg 164 included the Schlumberger quad-combination tool (NGT, LSS/SDT, DIT, CNT-G, HLDT), the Formation MicroScanner (FMS), and the Geochemical Combination Tool (GST). Electrical resistivity (DIT) and acoustic transit-time (LSS/SDT) downhole logs from Sites 994, 995, and 997 indicate the presence of gas hydrate in the depth interval between 185 and 450 mbsf on the Blake Ridge. Electrical resistivity log calculations suggest that the gas hydrate-bearing sedimentary section on the Blake Ridge may contain between 2 and 11 percent bulk volume (vol%) gas hydrate. We have determined that the log-inferred gas hydrates and underlying free-gas accumulations on the Blake Ridge may contain as much as 57 trillion m**3 of gas.

Theoretical analysis and numerical verification of the consistency of viscous smoothed-particle-hydrodynamics formulations in simulating free-surface flows

The theoretical formulation of the smoothed particle hydrodynamics (SPH) method deserves great care because of some inconsistencies occurring when considering free-surface inviscid flows. Actually, in SPH formulations one usually assumes that (i) surface integral terms on the boundary of the interpolation kernel support are neglected, (ii) free-surface conditions are implicitly verified. These assumptions are studied in detail in the present work for free-surface Newtonian viscous flow. The consistency of classical viscous weakly compressible SPH formulations is investigated. In particular, the principle of virtual work is used to study the verification of the free-surface boundary conditions in a weak sense. The latter can be related to the global energy dissipation induced by the viscous term formulations and their consistency. Numerical verification of this theoretical analysis is provided on three free-surface test cases including a standing wave, with the three viscous term formulations investigated.

Bernstein polynomials in element-free Galerkin method

In the recent decades, meshless methods (MMs), like the element-free Galerkin method (EFGM), have been widely studied and interesting results have been reached when solving partial differential equations. However, such solutions show a problem around boundary conditions, where the accuracy is not adequately achieved. This is caused by the use of moving least squares or residual kernel particle method methods to obtain the shape functions needed in MM, since such methods are good enough in the inner of the integration domains, but not so accurate in boundaries. This way, Bernstein curves, which are a partition of unity themselves,can solve this problem with the same accuracy in the inner area of the domain and at their boundaries.

Analytic free-form lens design for tracking integration in concentrating photovoltaics

In this work the concept of tracking integration in concentrating photovoltaics (CPV) is revisited and developed further. With respect to conventional CPV, tracking integration eliminates the clear separation between stationary units of optics and solar cells, and external solar trackers. This approach is capable of further increasing the concentration ratio and makes high concentrating photovoltaics (> 500x) available for single-axis tracker installations. The reduced external solar tracking effort enables possibly cheaper and more compact installations. Our proposed optical system uses two laterally moving plano-convex lenses to achieve high concentration over a wide angular range of ±24°. The lateral movement allows to combine both steering and concentration of the incident direct sun light. Given the specific symmetry conditions of the underlying optical design problem, rotational symmetric lenses are not ideal for this application. For this type of design problems, a new free-form optics design method presented in previous papers perfectly matches the symmetry. It is derived directly from Fermat's principle, leading to sets of functional differential equations allowing the successive calculation of the Taylor series coeficients of each implicit surface function up to very high orders. For optical systems designed for wide field of view and with clearly separated optical surfaces, this new analytic design method has potential application in both fields of nonimaging and imaging optics.

Physical parameters in relation to physiological changes of avocado during ripening (20ºc) and cold storage (6ºc) in different conditions.

The application of the response of fruits to low energy for mechanical impacts is described, for evaluation of post-harvest ripening of avocadoes of the variety "Hass". An impactor of 50g of weight, provided with an accelerometer, and free-falling from a height of 4 cm, is used; it is interfaced to a computer and uses a special software for retrieving and analyzing the deceleration data. Impact response parameters of individual fruits were compared to firmness of the pulp, measured by the most used method of double-plate puncture, as well as to other physical and physiological parameters: color, skin puncture ethylene production rate and others. Two groups of fruits were carefully selected, stored at 6º C (60 days) and ripened at 20ºC (11 days), and tested during the storage period. It is shown that, as in other types of fruits, impact response can be a good predictor of firmness in avocadoes, obtaining the same accuracy as with destructive firmness measurements. Mathematical and multiple regression models are calculated and compared to measured data, with which a prediction of storage period can be made for these fruits.

Soft solution fluorine-free synthesis of anatase nanoparticles with tailored morphology

TiO2 nanoparticles with tailored morphology have been synthesized under exceptionally soft conditions. The strategy is based on the use of a non-aqueous alcoholic reaction medium in which water traces, coming either from the air (atmospheric water) or from an ethanol–water azeotropic mixture (ethanol 96%), are incorporated in order to accelerate hydrolysis of the Ti–precursor. Moreover, organic surfactants have been used as capping agents so as to tailor crystal growth in certain preferential directions. Combinations of oleic acid and oleylamine, which lead to the formation of another surfactant, dioleamide, are employed instead of fluorine-based compounds, thus increasing the sustainability of the process. As a result, TiO2 nanostructured hierarchical microspheres and individual nanoparticles with exposed high-energy facets can be obtained at atmospheric pressure and temperatures as low as 78 °C.

Flammability conditions for ultra-lean hydrogen premixed combustion based on flame-ball analyses

It has been reasoned that the structures of strongly cellular flames in very lean mixtures approach an array of flame balls, each burning as if it were isolated, thereby indicating a connection between the critical conditions required for existence of steady flame balls and those necessary for occurrence of self-sustained premixed combustion. This is the starting assumption of the present study, in which structures of near-limit steady sphericosym-metrical flame balls are investigated with the objective of providing analytic expressions for critical combustion conditions in ultra-lean hydrogen-oxygen mixtures diluted with N2 and water vapor. If attention were restricted to planar premixed flames, then the lean-limit mole fraction of H2 would be found to be roughly ten percent, more than twice the observed flammability limits, thereby emphasizing the relevance of the flame-ball phenomena. Numerical integrations using detailed models for chemistry and radiation show that a onestep chemical-kinetic reduced mechanism based on steady-state assumptions for all chemical intermediates, together with a simple, optically thin approximation for water-vapor radiation, can be used to compute near-limit fuel-lean flame balls with excellent accuracy. The previously developed one-step reaction rate includes a crossover temperature that determines in the first approximation a chemical-kinetic lean limit below which combustión cannot occur, with critical conditions achieved when the diffusion-controlled radiation-free peak temperature, computed with account taken of hydrogen Soret diffusion, is equal to the crossover temperature. First-order corrections are found by activation-energy asymptotics in a solution that involves a near-field radiation-free zone surrounding a spherical flame sheet, together with a far-field radiation-conduction balance for the temperature profile. Different scalings are found depending on whether or not the surrounding atmosphere contains wáter vapor, leading to different analytic expressions for the critical conditions for flame-ball existence, which give results in very good agreement with those obtained by detailed numerical computations.

A free real-time hourly tilted solar irradiation data Website for Europe

The engineering of solar power applications, such as photovoltaic energy (PV) or thermal solar energy requires the knowledge of the solar resource available for the solar energy system. This solar resource is generally obtained from datasets, and is either measured by ground-stations, through the use of pyranometers, or by satellites. The solar irradiation data are generally not free, and their cost can be high, in particular if high temporal resolution is required, such as hourly data. In this work, we present an alternative method to provide free hourly global solar tilted irradiation data for the whole European territory through a web platform. The method that we have developed generates solar irradiation data from a combination of clear-sky simulations and weather conditions data. The results are publicly available for free through Soweda, a Web interface. To our knowledge, this is the first time that hourly solar irradiation data are made available online, in real-time, and for free, to the public. The accuracy of these data is not suitable for applications that require high data accuracy, but can be very useful for other applications that only require a rough estimate of solar irradiation.