O utjecaju pojedinih parametara ložišta izvedenih iz Rothermelovog modela ravnoteže toplinske energije na stopu širenja požara

We analysed the role of some fuel bed properties on forest fire-spread rate based on the thermal energy balance upon which the well-known fire-spread rate model of Rothermel (1972) was developed, showing that neither fuel bed height, load or density directly influence the thermal energy balance. The influence of such parameters, often inferred from empirical descriptions of spread rate, must result from indirect effects on heat transfer mechanisms. The fraction of heat transferred from the flame to the unburned fuel depends mostly on fuel moisture content and is independent of spread rate and flame geometry. Because empirical models usually implicitly assume the underlying mechanisms of fire spread for describing fire behaviour, this study results can assist at idealizing and delineating future experiments and approaches.Analizirana je uloga pojedinih svojstava ložišta u stopi širenja šumskog požara, na temelju ravnoteže toplinske energije, iz koje je razvijen poznati Rothermelov model širenja požara (1972), pokazujući da niti visina ložišta, jednako kao ni količina i gustoća ne utječu izravno na ravnotežu toplinske energije. Utjecaj tih parametara, često izvedenih iz empirijskih opisa stope širenja, nužno proizlazi iz neizravnih utjecaja na mehanizme prijenosa topline. Udio topline prenesen iz plamena na nesagorijelo gorivo, pretežno ovisi o sadržaju vlage u gorivu te je neovisan od stope širenja te oblika plamena. S obzirom na to da empirijski modeli uglavnom impliciraju mehanizme širenja požara u opisivanju njegovog ponašanja, rezultati ove studije mogu biti od pomoći u osmišljavanju i ocrtavanju budućih eksperimenata i pristupa

Hydration of Barium Monohydroxide in (H2O)1-3 Clusters: Theory and Experiment

The ionization energies (IEe´s) of small BaOH(H2O)m clusters (m = 1-3), as generated in a laser vaporization-supersonic expansion source have been determined by laser photoionization experiments over the 3.65?4.55 eV energy range. Complementary ab initio studies show that the IEe´s are in good agreement with computed adiabatic ionization energies, and that BaOH(H2O)m structures with a direct coordination of the Ba atom to water molecules are favored over those that are characterized by H-bonded networks involving H2O molecules and the OH group of BaOH. Additional calculations have been performed on the hydration energies for the most stable isomers of the relevant BaOH(H2O)1-3 clusters. A comparison is made between the closed-shell title system and the results of related theoretical studies on the open-shell alkali monohydroxides, which allows for an interpretation of the opposite trends that are found in the cluster size dependence of the vertical ionization energies for both series of systems, and highlights the role of the BaOH unpaired electron in its ionization process. Altogether, the present evidence suggests for the initial steps of the BaOH hydration process to be dominated by electrostatic and polarization interactions between the Ba+ and OH? ion cores, which become both increasingly solvated upon sequential addition of water molecules.Fil: Cabanillas Vidosa, Ivan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Rossa, Maximiliano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto de Investigaciones En Físicoquímica de Córdoba; ArgentinaFil: Pino, Gustavo Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto de Investigaciones En Físicoquímica de Córdoba; ArgentinaFil: Ferrero, Juan Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto de Investigaciones En Físicoquímica de Córdoba; ArgentinaFil: Cobos, Carlos Jorge. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentin

MKK3/6-p38 MAPK Signaling Is Required for IL-1β and TNF-α-Induced RANKL Expression in Bone Marrow Stromal Cells

Coupled bone turnover is directed by the expression of receptor-activated NF-κB ligand (RANKL) and its decoy receptor, osteoprotegerin (OPG). Proinflammatory cytokines, such as interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) induce RANKL expression in bone marrow stromal cells. Here, we report that IL-1β and TNF-α-induced RANKL requires p38 mitogen-activating protein kinase (MAPK) pathway activation for maximal expression. Real-time PCR was used to assess the p38 contribution toward IL-1β and TNF-α-induced RANKL mRNA expression. Steady-state RANKL RNA levels were increased approximately 17-fold by IL-1β treatment and subsequently reduced ∼70%–90% when p38 MAPK was inhibited with SB203580. RANKL mRNA stability data indicated that p38 MAPK did not alter the rate of mRNA decay in IL-1β-induced cells. Using a RANKL-luciferase cell line receptor containing a 120-kB segment of the 5' flanking region of the RANKL gene, reporter expression was stimulated 4–5-fold by IL-1β or TNF-α treatment. IL-1β-induced RANKL reporter expression was completely blocked with specific p38 inhibitors as well as dominant negative mutant constructs of MAPK kinase-3 and -6. In addition, blocking p38 signaling in bone marrow stromal cells partially inhibited IL-1β and TNF-α-induced osteoclastogenesis in vitro. Results from these studies indicate that p38 MAPK is a major signaling pathway involved in IL-1β and TNF-α-induced RANKL expression in bone marrow stromal cells.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63223/1/jir.2006.26.719.pd

Animal Models to Study Host-Bacteria Interactions Involved in Periodontitis

Animal models have distinct advantages because they can mimic cellular complexities that occur in humans in vivo and are often more accurate than in vitro studies that take place on plastic surfaces with limited numbers of cell types present. Furthermore, cause and effect relationships can be established by applying inhibitors or activators or through the use of genetically modified animals. Such gain or loss of function studies are often difficult to achieve in human clinical studies, particularly in obtaining target tissue due to important ethical considerations. Animal models in periodontal disease are particularly important at this point in the development of the scientific basis for understanding the predominant pathological processes. Periodontal disease can be broken down into discrete steps, each of which may be studied separately depending upon the animal model. These steps involve the development of a pathogenic biofilm, invasion of connective tissue by bacteria or their products, induction of a destructive host response in connective tissue and limitation of are pair process that follows tissue breakdown. Animal studies can test hypotheses related to each of these steps, and should be evaluated by their capacity to test a specific hypothesis rather than recapitulating all aspects of periodontal disease. Thus, each of the models described below can be adapted to test discrete components of the pathological process of periodontal disease, but not necessarily all of them

A mechanics-based model for simulation and control of flexible needle insertion in soft tissue

AbstractIn needle-based medical procedures, beveled-tip exible needles are steered inside soft tissue with the aim of reaching pre-dened target locations. The efciency of needle-based interventions depends on accurate control of the needle tip. This paper presents a comprehensive mechanics-based model for simulation of planar needle insertion in soft tissue. The proposed model for needle deection is based on beam theory, works in real-time, and accepts the insertion velocity as an input that can later be used as a control command for needle steering. The model takes into account the effects of tissue deformation, needle-tissue friction, tissue cutting force, and needle bevel angle on needle deection. Using a robot that inserts a exible needle into a phantom tissue, various experiments are conducted to separately identify different subsets of the model parameters. The validity of the proposed model is veried by comparing the simulation results to the empirical data. The results demonstrate the accuracy of the proposed model in predicting the needle tip deection for different insertion velocities. I

Analysis of glucose carbon fluxes in continuous cultures of Bacillus thuringiensis

The glucose carbon fluxes in continuous cultures of Bacillus thuringiensis grown in a complex medium have been studied as a function of the growth rate. The results are discussed in the light of a growth model. From reduced nicotinamide adenine dinucleotide (NADH) and carbon balances it was determined that the fraction of glucose consumed for biomass synthesis decreased with the growth rate, while the glucose flux through the tricarboxylic acid (TCA) cycle diminished after a threshold value of D=0.34 h-1, where D=dilution rate. At the highest growth rate tested, glucose was used almost exclusively as the energy source, via fermentative pathways, which indicates that the yeast extract was used as the carbon source. The specific rate of oxygen consumption increased with growth even after the beginning of the accumulation of acids, indicating that the respiratory chain was not saturated. The results suggest that there is a mismatch between glycolysis and TCA cycle capacity, depending on the growth rate. Furthermore, values of (P/O) ratio and mATP are presented, where (P/O) is mole of ATP formed per gram atom oxygen consumed by the respiratory chains and mATP is the maintenance requirement for ATP.Centro de Investigación y Desarrollo en Fermentaciones Industriale

Responses of Rhopalosiphum padi (L.) (Homoptera: Aphididae) on different wheat cultivars under laboratory conditions

Bird cherry-oat aphid, Rhopalosiphum padi (L.), a polyphagous species with a worldwide distribution, is an important pest of wheat as well as the main vector of barley yellow dwarf virus. The development, survivorship, and life table parameters of R.padi were evaluated in a growth chamber on seven wheat cultivars as follows: ACA 315, Baguette 12 P, BioInta 1002, BioInta 2004, Buck Meteoro, Klein Yarará and LE 2330 at controlled conditions (20±1°C; about 70% RH; 14h photophase). The development times of immatures ranged from 6.6 days on Buck Meteoro to 9.9 days on ACA315, whereas immature survival was 90 to 100%. The intrinsic rate of increase (rm) for ACA 315, Baguette 12 P and BioInta 2004 were the highest. Jackknife estimates of rm ranged from 0.327 to 0.204 females/female/day on BioInta 1002 and ACA315, respectively. The mean population generation times (T) on these hosts ranged from 10.91 to 19.66 days. The highest net reproductive rate (R0) were on BioInta 2004 (98.98 females/female/generation) and the lowest on BioInta 1002, Buck Meteoro, Klein Yarará and LE 233 (35.32 to 39.59). Because of the high coefficient of determination (pseudo-R2) values in Gompertz and Weibul models, survival data from different cultivars had a good fit to both models. The results pointed ACA 315, Baguette 12 P and partially BioInta 2004 as the least suitable host plants, indicating that they were the most resistant to R. padi among the cultivars we tested.Inst. de Microbiología y Zoología Agrícola IMyZAFil: La Rossa, Francisco Ruben. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Microbiología y Zoología Agrícola; ArgentinaFil: Giudici, Albano Cesar. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Microbiología y Zoología Agrícola; ArgentinaFil: Vasicek, Araceli. Universidad Nacional de La Plata. Facultad de Ciencias Agrarias y Forestales. Cátedra de Zoología Agrícola; ArgentinaFil: López, María Carolina. Universidad Nacional de La Plata. Facultad de Ciencias Agrarias y Forestales. Cátedra de Zoología Agrícola; ArgentinaFil: Bainotti, Carlos Tomas. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Marcos Juárez; Argentin

Clopidogrel Enhances Periodontal Repair in Rats Through Decreased Inflammation

Aim We hypothesized that platelet inactivation induced by drugs might interfere with periodontal repair in experimental periodontitis by suppressing the release of biological mediators from platelets at the site of injury. Material and Methods 60 rats were randomly assigned to 6 groups (n=10) and ligatures were placed around lower first molars of three groups. The other three groups were used as negative controls. Ligatures were removed after 10 days of periodontitis induction and all groups were submitted to treatment with aspirin (Asp) (30 mg/kg), clopidogrel (Clop) (75 mg/kg) or NaCl 0.9% intragastrically once daily for 3 days. Periodontal tissue was assessed by the measurement of CXCL12, CXCL4, CCL5 and PDGF by ELISA; histomorphometric analysis of PMN infiltration, attachment loss, bone loss and osteoclast numbers and quantification of blood vessels by imunnohistochemistry. Results During periodontal repair and treatment with NaCl 0.9%, CCL5 was decreased and CXCL12 increased when compared to negative control groups. Asp and Clop did not affect CCL5 expression, decreased CXCL12 but only Clop decreased CXCL4 and PDGF content compared to saline-treated animals. Clop increased blood vessel number, reduced PMN count, and decreased attachment and bone loss, also decreased osteoclast number in animals submitted or not to periodontal repair. Conclusion Systemic administration of Clop during 3 days improved the repair process associated with experimental periodontal disease, suggesting that it may have therapeutic value under situations where tissues undergo a transition from inflammation to repair

Effect of host plant on biology and life table parameters of Sipha maydis (Pass.) (Hemiptera: Aphididae)

Sipha (Rugsia) maydis (Pass.) is an important pest of wheat and it has been reported throughout the Mediterranean region, into Central and South Asia, South Africa, South America and North America The development, survivorship, and life table parameters of R. padi were evaluated in a growth chamber on seven wheat cultivars as follows: ACA 315, Baguette 12 P, BioINTA 1002, BioINTA 2004, Buck Meteoro, Klein Yarará and LE 2330 at controlled conditions (20±1°C; about 70% RH; 14 h photophase). The development time of immature stage was ca. 8-9 d on cv. ACA 315, BioINTA 1002, Buck Meteoro, Klein Yarará and LE 2330, while those on cvs BioINTA 2004 and Baguette 12 P was ca. 11-12 d. The immature survival ranged from 90 to 100%. The intrinsic rate of increase (rm) for ACA 315 and BioINTA 2004 were the highest. Jackknife estimates of rm on all cultivars ranged from 0.199 to 0.093 females/female/day on ACA 315 and LE 2330, respectively. The mean generation times (T) ranged from 22.82 d on Baguette 12 P to 15.09 d on Klein Yarará. The highest net reproductive rate (R0) were on ACA 315 and Baguette 12 P (59.80 and 53.25 females/female/generation, respectively). Because of the high coefficient of determination (pseudo-R2) values in Gompertz and Weibull models, survival data from different cultivars had a good fit to both models. The results pointed LE 2330, Klein Yarará and partially BioINTA 1002 as the least suitable host plants, indicating that they were the most resistant to S. maydis among the cultivars tested.Inst. de Microbiología y Zoología Agrícola IMyZAFil: La Rossa, Francisco Ruben. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Microbiología y Zoología Agrícola; ArgentinaFil: Giudici, Albano Cesar. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Microbiología y Zoología Agrícola; ArgentinaFil: Vasicek, Araceli. Universidad Nacional de La Plata. Facultad de Ciencias Agrarias y Forestales. Cátedra de Zoología Agrícola; ArgentinaFil: López, María Carolina. Universidad Nacional de La Plata. Facultad de Ciencias Agrarias y Forestales. Cátedra de Zoología Agrícola; ArgentinaFil: Bainotti, Carlos Tomas. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Marcos Juárez; Argentin

Pinturas pigmentadas con magnetita dopada : evaluación preliminar de propiedades anticorrosivas

RESUMEN: La magnetita pura y las magnetitas dopadas con cobre y cromo se sintetizaron a escala de laboratorio. El comportamiento relativo de estos productos como pigmentos anticorrosivos se comparó con la hematita disponible comercialmente (óxido rojo del hierro). Se prepararon mezclas especiales de los pigmentos con resina epoxy libre de solvente manteniendo el contenido del volumen de pigmento cerca del valor práctico crítico. El propósito es distinguir la acción inhibidora de los pigmentos con poca influencia de las características de la barrera de la resina epóxica. El comportamiento de las mezclas aplicadas sobre el acero se caracterizó mediante exposición acelerada al aire libre, en pruebas alternadas de inmersión y en condiciones de inmersión total. Esta última prueba se supervisó con medidas de potencial y de impedancia de circuito abierto, y fueron complementadas con evaluación de películas libres. Los resultados demuestran que la magnetita no es un pigmento inerte, y que la presencia de elementos dopantes puede mejorar el comportamiento de las pinturas anticorrosivas de magnetita. Basados en esos resultados, se sugirió una formulación completa con pigmento de magnetita, solvente y aditivos y se evaluó en laboratorio, teniendo como objetivo el uso posible como pintura anticorrosivaABSTRACT: Pure magnetite and magnetite doped with three different concentrations of chromium and copper was lab synthesized. The relative performance of these products as anticorrosive pigments is compared with commercially available hematite (red iron oxide). Special mixtures of the pigments with a solventless epoxy binder were prepared maintaining the pigment volume contents near the practical critical value. The purpose was to distinguish the inhibitive action of pigments with the least possible influence from the barrier properties of the epoxy resin. The performance of mixtures applied on mild steel is characterized in accelerated outdoor exposure, in alternated immersion tests and in total immersion conditions. The latter test was monitored with open circuit potential and impedance measurements. Complementary tests with freestanding films were also performed. The results show that magnetite is not an inert pigment, Therefore presence of doping elements can improve the performance of anticorrosive magnetite paints. Based on this result, a complete formulation with pigment, solvent and additives is suggested and preliminarily tested in the lab aiming at producing an anticorrosive primer