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881.
Miguel Almeida José Raul Azinheira Jorge Barata Kouamana Bousson Rita Ervilha Marta Martins Alexandra Moutinho José Carlos Pereira João Caldas Pinto Luís Mário Ribeiro Jorge Silva Domingos Xavier Viegas 《Fire Technology》2017,53(2):553-575
The most common location for campsites is in forested or arborous areas. Given the regular use of combustible material by campers and the frequent use of campfires to cook, campsites become areas with a high propensity for the occurrence of fires. Moreover, fires occurring close to campsites can cause evacuations, disturbing their regular activities and jeopardizing tourism and likewise economic activities. While some campsites have tents and caravans within a secure distance of each other, many other campsites have the tents and caravans very concentrated in a limited area, making it much easier for fire to spread from a tent to the next. Despite the occurrence of several of these events, the associated risk is currently not well studied or documented. The work presented in this paper was performed within the Portuguese research project FireCamp, whose main purpose was the analysis and documentation of the fire risk in campsites. Several topics were addressed and some of them will be presented within this paper, specifically: (1) understanding of the mechanisms associated to burning tents; (2) analysis of the combustibility of typical accessories used in campsites such as tents, sleeping bags or camping mattresses; (3) characterization of a campsite fuel cover and its surroundings via image analysis taken by unmanned aerial vehicles; and (4) modeling of fire spread in campsites. A pilot study was carried out between 2011 and 2014 in the Campsite of Côja, in Arganil—Coimbra—Portugal. Taking into consideration that external fires frequently threaten these sites, complementary to the analysis of the fuel distribution inside the campsite, the land use analysis in the surrounding area is also of great interest. Thus, a fuel map of the Campsite of Côja was produced based on a high-resolution map of the area obtained by aerial photography produced by drones. Based on this fuel map, a stochastic model was set up to predict the fire spread in the covered area. The results obtained in this pilot study are hereby presented. Additionally, several laboratory tests were carried out in order to analyze the high calorific values (HCV) and the time to ignition (TTI) of the materials of typical camping accessories. The values of HCV found are in the range of 22.45–45.45 MJ kg?1 and the values of TTI found are in the range of 118–224 s. These values show a high propensity for these materials to spread fire. Real tents with and without typical accessories inside (e.g., sleeping bags) were burnt in controlled environment in order to determine the mass loss decay, the increase of temperature and the convective airflows produced. Due to the convective flow inside the tent, these parameters were not considered as valid but these tests were important to understand the mechanisms associated to the burning of tents and the risk associated. The presence of combustible material inside a tent was found to be of high importance in order to sustain the combustion. 相似文献
882.
Catalytic methods are important tools for the synthesis of C-C bonds under mild and ambient conditions. Palladium chemistry predominates in this area because it offers the opportunity to form several different types of bonds in one pot. Palladium can also tolerate a variety of functional groups. Among the many investigations of catalytic aryl-aryl couplings, the most successful technique has been the Suzuki reaction, which uses an arylboronic acid to attack an aryl-Pd bond. This Account reports our methodology, based on the cooperative action of Pd and norbornene, that achieves selective aryl-aryl coupling through C-halide and C-H activation. We are primarily interested in Pd-catalyzed sequential reactions. These reactions combine palladium as an inorganic catalyst and a strained olefin such as norbornene as an organic catalyst and can lead to biphenyl derivatives. While the palladium facilitates C-C bond formation through C-halide and C-H activation, the norbornene contributes to the construction of a palladacycle, an intermediate structure that controls and directs the subsequent reaction steps selectively. To achieve regioselective arylation at the carbon ortho to the original C-halide bond, palladacycles require an additional ortho substituent (R(1)). The palladacycle opens, giving rise to a biphenylylnorbornylpalladium complex. Because of the steric hindrance exerted by the two ortho groups, norbornene deinsertion readily occurs to form a biphenylylpalladium complex. Thus, norbornene acts as a removable scaffold. We used this biphenylylpalladium species to form C-C (with olefins, alkynes, or arylboronic acids) or C-H bonds (by hydrogenolysis). Using nonidentical aryl or heteroaryl halides, we also formed a biaryl-bonded Pd species able to undergo the final termination reaction (C-C, C-N, or C-O bond formation) either inter- or intramolecularly. We used this method to synthesize a variety of aromatic and heteroaromatic compounds. We also obtained the key metallacycle able to selectively direct the reactions by replacing norbornene with an aryl-bonded aminocarbonyl group. This method provided a diverse series of condensed heterocycles. 相似文献
883.
Arroyo M Rocandio AM Ansotegui L Pascual E Martínez de la Pera C 《Archivos latinoamericanos de nutrición》2008,58(1):27-32
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. 相似文献
884.
Milk fat is a complex mixture of geometric and positional isomers of monounsaturated and polyunsaturated, including short-,
long- and branch-chain fatty acids (FAs). There has been partial success to resolve this mixture of FAs using different GC
temperature programs, or a combination of GC isothermal and temperature programs. To overcome the problem associated with
overlapping isomers prior silver-ion separation was recommended. However, this procedure is time consuming and not practical
for routine analysis. In addition, previous methods focused mainly on the trans and cis isomers of 18:1. The present method takes advantage of differences in the relative elution times between different types
of FAs. The method involved analyzing each milk fat using the same highly polar 100-m capillary column and GC instrument,
and conducting two separations using temperature programs that plateau at 175 and 150 °C. The relative shift among the geometric
and positional isomers at these two temperature settings was enough to permit identification of most of the trans and cis 16:1, 18:1 and 20:1, the c/t-18:2 and the c/c/t-18:3 isomers found in milk fat. The identity of these FAs was confirmed by prior separation of the total fatty acid methyl
esters (FAMEs) of milk fat using Ag+-SPE columns, and comparing the fractions to the total milk fat. The Ag+-SPE technique was modified to obtain pure saturated, trans- and cis-monounsaturated and diunsaturated FAMEs. By combining the results from these two separate GC analyses, knowing the elution
order, it was possible to determine most of the geometric and positional isomers of 16:1, 18:1, 20:1, 18:2 and 18:3 without
a prior silver-ion separation. Only few minor FAs could not be resolved, notable the conjugated linoleic acid isomers that
still required the complimentary Ag+-HPLC separation. The two GC temperature programs have been successfully used to routinely analyze most FA isomers in total
milk and beef fats in about 200 min without the use of prior silver-ion separations. 相似文献
885.
Elevated PBDE levels in pet cats: sentinels for humans? 总被引:1,自引:0,他引:1
Dye JA Venier M Zhu L Ward CR Hites RA Birnbaum LS 《Environmental science & technology》2007,41(18):6350-6356
Co-incident with the introduction of polybrominated diphenyl ethers (PBDEs) into household materials nearly 30 years ago, feline hyperthyroidism (FH) has increased dramatically. Risk of developing FH is associated with indoor living and consumption of canned catfood. We hypothesized that increases in FH were, in part, related to increased PBDE exposure, with key routes of exposure being diet and ingestion of house dust. This study was designed to determine whether body burdens of PBDEs in hyperthyroid (HT) cats were greater than that of young or sick non-HT cats. Serum samples and clinical information were collected from 23 cats. Serum and dry and canned cat food were analyzed for PBDEs. A spectrum of BDE congeners was detected in all cats, with BDE-47, 99, 207, and 209 predominating. Mean +/- standard error (and median) cumulative sigma PBDE serum concentrations of young, old non-HT, and HT cats were 4.3 +/- 1.5 (3.5), 10.5 +/- 3.5 (5.9), and 12.7 +/- 3.9 (6.2) ng/mL, respectively. Due to high variability within each group, no association was detected between HT cats and sigma PBDE levels. Indicative of age- or disease-dependent changes in PBDE metabolism, BDE-47/99 ratios were inversely correlated with age, and 47/99 and 100/ 99 ratios in HT cats were significantly lower than those in the other cats. Overall, sigma PBDE levels in cats were 20- to 100-fold greater than median levels in U.S. adults. Our results support the hypothesis that cats are highly exposed to PBDEs; hence, pet cats may serve as sentinels to better assess human exposure and adverse health outcomes related to low-level but chronic PBDE exposure. 相似文献
886.
Deperas J Szluinska M Deperas-Kaminska M Edwards A Lloyd D Lindholm C Romm H Roy L Moss R Morand J Wojcik A 《Radiation protection dosimetry》2007,124(2):115-123
The aim of biological dosimetry is to estimate the dose and the associated uncertainty to which an accident victim was exposed. This process requires the use of the maximum-likelihood method for fitting a calibration curve, a procedure that is not implemented in most statistical computer programs. Several laboratories have produced their own programs, but these are frequently not user-friendly and not available to outside users. We developed a software for fitting a linear-quadratic dose-response relationship by the method of maximum-likelihood and for estimating a dose from the number of aberrations observed. The program called as CABAS consists of the main curve-fitting and dose estimating module and modules for calculating the dose in cases of partial body exposure, for estimating the minimum number of cells necessary to detect a given dose of radiation and for calculating the dose in the case of a protracted exposure. The program is freely available at http://www.pu.kielce.pl/ibiol/cabas. 相似文献
887.
Parazzini M Tognola G Franzoni C Grandori F Ravazzani P 《IEEE transactions on bio-medical engineering》2007,54(1):39-48
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. 相似文献
888.
Marta Pozo Gil 《Architectural Design》2013,83(3):48-55
Architect Marta Pozo Gil , who leads the Sustainability Department at MVRDV, draws on a correlation between people's retreat indoors, with urban populations becoming increasingly divorced from nature, and the growing ambitions for ‘green’ cities and the ensuing benefits they bring to our quality of life. How might it, though, be possible to realise such a vision? Pozo Gil describes some of MVRDV's lesser-known projects that weave nature into the city. 相似文献
889.
Marina Rigau Mireia Olivan Marta Garcia Tamara Sequeiros Melania Montes Eva Colás Marta Llauradó Jacques Planas Inés de Torres Juan Morote Colin Cooper Jaume Reventós Jeremy Clark Andreas Doll 《International journal of molecular sciences》2013,14(6):12620-12649
In order to successfully cure patients with prostate cancer (PCa), it is important to detect the disease at an early stage. The existing clinical biomarkers for PCa are not ideal, since they cannot specifically differentiate between those patients who should be treated immediately and those who should avoid over-treatment. Current screening techniques lack specificity, and a decisive diagnosis of PCa is based on prostate biopsy. Although PCa screening is widely utilized nowadays, two thirds of the biopsies performed are still unnecessary. Thus the discovery of non-invasive PCa biomarkers remains urgent. In recent years, the utilization of urine has emerged as an attractive option for the non-invasive detection of PCa. Moreover, a great improvement in high-throughput “omic” techniques has presented considerable opportunities for the identification of new biomarkers. Herein, we will review the most significant urine biomarkers described in recent years, as well as some future prospects in that field. 相似文献
890.
Marta Prasek Ewa Sawosz Slawomir Jaworski Marta Grodzik Teresa Ostaszewska Maciej Kamaszewski Mateusz Wierzbicki Andre Chwalibog 《Nanoscale research letters》2013,8(1):251
Platinum nanoparticles (NP-Pt) are noble metal nanoparticles with unique physiochemical properties that have recently elicited much interest in medical research. However, we still know little about their toxicity and influence on general health. We investigated effects of NP-Pt on the growth and development of the chicken embryo model with emphasis on brain tissue micro- and ultrastructure. The embryos were administered solutions of NP-Pt injected in ovo at concentrations from 1 to 20 μg/ml. The results demonstrate that NP-Pt did not affect the growth and development of the embryos; however, they induced apoptosis and decreased the number of proliferating cells in the brain tissue. These preliminary results indicate that properties of NP-Pt might be utilized in brain cancer therapy, but potential toxic side effects must be elucidated in extensive follow-up research. 相似文献