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771.
Kenny NA Warland JS Brown RD Gillespie TG 《International journal of biometeorology》2008,52(6):491-503
The complexities of the interactions between long- and short-wave radiation fluxes and the human body make it inherently difficult to estimate precisely the total radiation absorbed (R) by a human in an outdoor environment. The purpose of this project was to assess and compare three methods to estimate the radiation absorbed by a human in an outdoor environment, and to compare the impact of applying various skin and clothing albedos (alpha ( h )) on R. Field tests were conducted under both clear and overcast skies to evaluate the performance of applying a cylindrical radiation thermometer (CRT), net radiometer, and a theoretical estimation model to predict R. Three albedos were evaluated: light (alpha ( h ) = 0.57), medium (alpha ( h ) = 0.37), and dark (alpha ( h ) = 0.21). During the sampling periods, the range of error between the methods used to estimate the radiation absorbed by a cylindrical body under clear and overcast skies ranged from 3 to 8%. Clothing and skin albedo had a substantial impact on R, with the mean change in R between the darkest and lightest albedos ranging from 115 to 157 W m( - 2) over the sampling period. Radiation is one of the most important variables to consider in outdoor thermal comfort research, as R is often the largest contributor to the human energy balance equation. The methods outlined and assessed in this study can be conveniently applied to provide reliable estimates of the radiation absorbed by a human in an outdoor environment. 相似文献
772.
John R. Barton Andreas Schneider Johannes Jager 《The International Journal of Life Cycle Assessment》2002,7(1):11-17
Establishing BAT (Best Available Techniques) for processes subject to IPPC is a new barrier and one that processes in the
development stage need to be aware of. For multi-functional processes, the sectorial approach adopted under IPPC (Integrated
Pollution Prevention and Control) increases the potential problems. Life Cycle Assessment (LCA) is an established tool to
assist establishing BAT but is difficult to apply in its full form at the Research and Development (R&D) stage. A review of
LCA in the context of a case study, the Trefoil kiln process, concludes that it has the flexibility to cope with multi-functionality
and that use of key environmental issues and key indicators could overcome the informational gaps. Environmental burdens can
be presented appropriately provided the research identifies appropriate allocation methods. The use of LCA thinking provided
useful insight on the content of the research programme. 相似文献
773.
Maja Berden-Zrimec Jasmina Kožar Logar Alexis Zrimec Luka Drinovec Mladen Franko Alenka Malej 《Central European Journal of Biology》2009,4(3):313-320
A new approach to the studies of the microalgal cell lysis by utilizing a combination of two complementary methods is presented.
Delayed fluorescence (DF) is a measure of the living algal biomass, detecting only cells with active photosynthesis. Thermal
lens spectrometry (TLS) detects the total pigment amount released from lysed cells. Both methods select for photosynthetic
organisms, reducing possible background from other sources (e.g. heterotrophic bacteria, zooplankton, and abiotic substances).
The DF/TLS method was tested with a laboratory Skeletonema costatum culture exposed to a geometric dilution series of the
lysing factor poly- APS. The exposure resulted in similar EC50 values for DF intensity, TLS and dissolved esterase activity of 0.8±0.2, 1.77±0.35, and 1.25±0.1 mg poly-APS l−1, respectively. The combined DF/TLS method enabled a rapid evaluation of the living vs. dead cells without any sample pretreatment
or manipulation. 相似文献
774.
A thermal therapy for cancer in skin tissue is numerically investigated using three bioheat conduction models, namely Pennes, thermal wave and dual-phase lag models. A laser is applied at the surface of the skin for cancer ablation, and the temperature and thermal damage distributions are predicted using the three bioheat models and two different modeling approaches of the laser effect. The first one is a prescribed surface heat flux, in which the tissue is assumed to be highly absorbent, while the second approach is a volumetric heat source, which is reasonable if the scattering and absorption skin effects are of similar magnitude. The finite volume method is applied to solve the governing bioheat equation. A parametric study is carried out to ascertain the effects of the thermophysical properties of the cancer on the thermal damage. The temperature distributions predicted by the three models exhibit significant differences, even though the temperature distributions are similar when the laser is turned off. The type of bioheat model has more influence on the predicted thermal damage than the type of modeling approach used for the laser. The phase lags of heat flux and temperature gradient have an important influence on the results, as well as the thermal conductivity of the cancer. In contrast, the uncertainty in the specific heat and blood perfusion rate has a minor influence on the thermal damage. 相似文献
775.
Preparation and characterization of cross-linked enzyme aggregates (CLEA) of subtilisin for controlled release applications 总被引:1,自引:0,他引:1
Enzyme stabilization is one of the major challenges in the biocatalytic process optimization. Subtilisin was aggregated using ammonium sulphate and polyethylene glycol with surfactants like triton X-100 and tween 20. The resultant aggregates on cross-linking with glutaraldehyde produced insoluble and catalytically active enzyme. The effect of pH, temperature, kinetic parameter, thermal stability and stability in organic solvents were studied. The cross-linked enzyme aggregates (CLEA) exhibited broad pH optima of 9.0 and higher temperature optima of 70 degrees C. Reusability and surface morphology of the CLEA were also studied. CLEA of subtilisin has good stability in nonpolar organic solvents, such as hexane, and cyclohexane and it has high thermal stability up to 60 degrees C and therefore can be used as a catalyst for the biotransformation of compounds which are not soluble in aqueous medium. The CLEAs were entrapped in the hydrogel composite beads of alginate:guar gum (3:1) which were resistant to low pH conditions in the stomach and thus was found to be useful for the oral drug delivery. This process can be used to deliver the protein and peptide drugs which involve high concentrations at the delivery stage, and which usually degrades in the stomach before reaching the jejunum. Application of these pH-sensitive beads for the controlled release of subtilisin in vitro was studied and found to be a feasible strategy. 相似文献
776.
Several experiments have shown that during propagation of the action potential in axons, thermal energy is locally exchanged.
In this paper, we use a simple model based on statistical physics to show that an important part of this exchange comes from
the physics of the effusion. We evaluate, during the action potential propagation, the variation of internal energy and of
the energy associated with the chemical potential of the effusion of water and ions to extract the thermal energy exchanged.
The temperature exchanged is then evaluated on the area where the action potential is active. Results give a good correspondence
between experimental work and this model, showing that an important part of the thermal energy exchange comes from the statistical
cooling power of the effusion. 相似文献
777.
In this work, we continue our studies on the thermal prebiotic oligomerization of amino acids. The next step is to consider all four types of electromagnetic interactions that our model may admit. In addition, only the polymerization of amino acids via the formation of diketopiperazine, which arises from the cyclodehydration of two amino acids, will be considered. By assuming that only one residue group of two will predominate in the diketopiperazine molecule, it is possible to reduce the three-body problem to a simpler situation with the two objects that we have already solved. 相似文献
778.
The inclusion compounds of carvone enantiomers in cylcomaltoheptaose (beta-cyclodextrin, betaCD) are studied at defined temperatures above room temperature and in relation to H-->D and D-->H exchanges. Loss of water molecules and release of carvone molecules from the betaCD cavity are caused by increase of temperature above room temperature and are measured by the integrated intensities of the O-H and C-H Raman stretching bands, respectively. In turn, H-->D and D-->H exchanges are monitored by the integrated intensities of the O-H and O-D Raman stretching bands, respectively. All of these processes were followed in real time with a Raman spectrometer equipped with CCD detection. The results indicate that distinct carvone enantiomers lead to the formation of different betaCD inclusion hydrates that have different water content and hydration structures. In particular, the results suggest that SCarv-betaCD has a greater water content, dehydrates strongly for temperatures above room temperature, and exchanges protons faster than the RCarv-betaCD complex. 相似文献
779.
Fluorescent and haptenized, monofunctionally binding platinum compounds are increasingly used for chemically labeling nucleic acids for hybridization detection purposes. Here we analyze in detail the effect of labeling density of the cyanin-3 and -5 platinum DNA adducts on fluorescence and thermal stability. We also analyzed the kinetics of the reaction of the cyanin platinum compounds with DNA. The data provided are important for the design of optimal platinum DNA labeling and hybridization conditions for fluorescence hybridization applications. 相似文献
780.
Computer prediction of human thermoregulatory and temperature responses to a wide range of environmental conditions 总被引:1,自引:0,他引:1
A mathematical model for predicting human thermal and regulatory responses in cold, cool, neutral, warm, and hot environments
has been developed and validated. The multi-segmental passive system, which models the dynamic heat transport within the body
and the heat exchange between body parts and the environment, is discussed elsewhere. This paper is concerned with the development
of the active system, which simulates the regulatory responses of shivering, sweating, and peripheral vasomotion of unacclimatised
subjects. Following a comprehensive literature review, 26 independent experiments were selected that were designed to provoke
each of these responses in different circumstances. Regression analysis revealed that skin and head core temperature affect
regulatory responses in a non-linear fashion. A further signal, i.e. the rate of change of the mean skin temperature weighted
by the skin temperature error signal, was identified as governing the dynamics of thermoregulatory processes in the cold.
Verification and validation work was carried out using experimental data obtained from 90 exposures covering a range of steady
and transient ambient temperatures between 5°C and 50°C and exercise intensities between 46 W/m2 and 600 W/m2. Good general agreement with measured data was obtained for regulatory responses, internal temperatures, and the mean and
local skin temperatures of unacclimatised humans for the whole spectrum of climatic conditions and for different activity
levels.
Received: 20 November 2000 / Revised: 24 April 2001 / Accepted: 14 May 2001 相似文献