Fire Performance of External Thermal Insulation Composite System (ETICS) Facades with Expanded Polystyrene (EPS) Insulation and Thin Rendering

External Thermal Insulation Composite System (ETICS) facades with expanded polystyrene (EPS) insulation and thin rendering are applied frequently in buildings. Considering high combustibility of EPS, with these facades concerns also arise regarding spread of a possible fire between neighbouring compartments of high-rise buildings. Fire tests of two large-scale facades were performed to study two parameters presumably influencing significantly the fires of such facades in real-life settings, i.e. incident heat flux upon the facade’s surface (IHFFS) and damage of the facade’s render (the latter being a consequence of poor or unfinished construction work, ageing or fire-induced thermal strain). The first facade was rendered fully and was exposed to moderately-fast increasing IHFFS. In the second (partially unrendered) facade case the IHFFS progressed faster. The facade flame body (temperatures and shape) was monitored by thermocouples, photo and video cameras. For detection of melting of EPS and internal burning, thermocameras were used within the facades areas outside the visible plume. In the plume zone, however, a group of thermocouples was embedded inside EPS and the shapes (plateaus and slopes) of the collected time-temperature graphs were observed for these purposes. The IHFFS imposed on the facades during fire testing were estimated by numerical calculations. In both cases the first pronounced render crack was evolved at the estimated average between-windows IHFFS of around 30 kW/m\(^2\) and was followed by internal burning of EPS. While the latter did not seem to spread across the facade for the fully-rendered facade, a fast fire spread was detected for the second specimen.     

Retrieval of suspended particulate matter concentrations in the Danube River from Landsat ETM data

Alternations in river channel morphology result in a disturbed natural transport of suspended particulate matter (SPM). Suspended particulate matter serves as a transport medium for various pollutants, e.g. heavy metals. It is therefore important to understand how artificial obstructions alter the natural transport of suspended matter. Measurements of SPM in rivers are traditionally carried out during in situ sampling campaigns, which can provide only a limited view of the actual spatial distribution of suspended matter over large distances. Several authors have studied how space-borne remote sensing could be used for mapping of water quality in standing waters, but with only little attention paid to rivers. This paper describes the methodology how a Landsat ETM image was used to map the spatial patterns of SPM in the Slovak portion of the Danube River. Results of our investigation reveal that the Danube River in Slovakia exhibits gradual longitudinal decrease in concentrations of SPM. Based on a strong relationship between the Landsat near-infrared band (TM4) and field measurements, we developed a map of suspended particulate matter in the Danube River with a standard error (SE) of 2.92 mg/L. This study aims to show how archived satellite data and historical water quality data can be used for monitoring of SPM in large rivers. A methodology describing the minimum samples required for sufficiently accurate results is discussed in this paper also.     

Evaluation of directional mesh bias in concrete fracture simulations using continuum damage models

In the present comparative study, we investigate the influence of directional mesh bias on the results of failure simulations performed with isotropic and anisotropic damage models. Several fracture tests leading to curved crack trajectories are simulated on different meshes. The isotropic damage model with a realistic biaxial strength envelope for concrete is highly sensitive to the mesh orientation, even for fine meshes. The sensitivity is reduced if the definition of the damage-driving variable (equivalent strain) is based on the modified von Mises criterion, but the corresponding biaxial strength envelope is not realistic for concrete. The anisotropic damage models used in this study capture reasonably well arbitrary crack trajectories even if the biaxial strength envelope remains close to typical experimental data. Their superior performance can be at least partially attributed to their ability to capture dilatancy under shear, which is revealed by a comparative analysis of the behavior of individual models under shear with restricted or free volume expansion.     

短流程制备镁合金板材的研究进展

镁合金板材在汽车、通讯、航空航天等领域有着巨大的应用潜力,而短流程环境友好的材料加工技术正逐渐成为国内外学者关注的焦点之一.系统介绍了镁合金板材短流程制备工艺的技术特点,综述了短流程镁板材制备的最新研究进展,分析了各工艺下板材的性能与微观组织,指出了短流程镁板材制备技术进一步发展的方向.     

From enzyme to zymogen: engineering Vip2, an ADP-ribosyltransferase from Bacillus cereus, for conditional toxicity

The adenosine diphosphate (ADP)-ribosyltransferase, Vip2 (vegetative insecticidal protein), from Bacillus cereus in combination with another protein from the same organism, Vip1, has insecticidal activity against western corn rootworm larvae. The Vip2 protein exerts its intracellular poisoning effect by modifying actin and preventing actin polymerization. Due to the nature of this toxin, expression of Vip2 in planta is lethal. In this work, we attempted to build an enzyme precursor (proenzyme, zymogen) that would silently reside in one biological system (e.g. plants or yeast) and be activated in the other (insect larvae). Our approach involved engineering a random propeptide library at the C-terminal end of Vip2 and selecting for malfunctional enzyme variants in yeast. A selected proenzyme (proVip2) possesses reduced enzymatic activity as compared with the wild-type Vip2 protein, but remains a potent toxin toward rootworm larvae. In addition, upon analysis of the digestive fate of the engineered enzyme precursor in rootworm larvae, we demonstrated that 'zymogenized' Vip2 can be proteolytically activated by rootworm digestive enzyme machinery. This report represents an example of applying a protein engineering strategy for the creation of a plant-tolerated, zymogen-like form of an otherwise toxic protein. This approach may outline a novel path to address challenges associated with utilizing toxic proteins in certain biotechnological applications.     

Diesel bus emissions measured in a tunnel study

The emission factors of a bus fleet consisting of approximately 300 diesel-powered buses were measured in a tunnel study under well-controlled conditions during a 2-d monitoring campaign in Brisbane. Particle number and mass concentration levels of submicrometer particles and PM2.5 were monitored by SMPS and DustTrak instruments at the tunnel's entrance and exit, respectively. Correlation between DustTrak and TEOM response to diesel emissions was assessed, and the DustTrak results were recalculated into TEOM equivalent data. The mean value of the number and mass emission factors was (3.11+/-2.41) x 10(14) particles km(-1) for submicrometer particles and 583+/-451 mg km(-1) for PM2.5 (DustTrak), respectively. TEOM PM2.5 equivalent emission factor was 267+/-207 mg km(-1). The results are in good agreement with the emission factors determined from steady-state dynamometer testing of 12 buses from the same Brisbane City bus fleet. The results indicate that when carefully designed, both approaches, the dynamometer and on-road studies, can provide comparable results, applicable for the assessment of the effect of traffic emissions on airborne particle pollution. A brief overview of emission factors determined from other on-road and dynamometer studies reported in the literature as well as with the regulatory values used for the vehicle emission inventory assessment is presented and compared with the results obtained in this study.     

In vivo visualization of cells labeled with superparamagnetic iron oxides by a sub-millisecond gradient echo sequence

Object

In vivo magnetic resonance imaging (MRI) of iron-labeled pancreatic islets (PIs) transplanted into the liver is still challenging in humans. The aim of this study was to develop and evaluate a double contrast method for the detection of PIs labeled with superparamagnetic iron oxide (SPIO) nanoparticles.

Materials and methods

A double-echo three-dimensional (3D) spoiled gradient echo sequence was adapted to yield a sub-millisecond first echo time using variable echo times and highly asymmetric Cartesian readout. Positive contrast was achieved by conventional and relative image subtraction. Experiments for cell detection efficiency were performed in vitro on gelatin phantoms, in vivo on a Lewis rat and on a patient 6 months after PI transplantation.

Results

It was demonstrated that the proposed method can be used for the detection of transplanted PIs with positive contrast in vitro and in vivo. For all experiments, relative subtraction yielded comparable and in some cases better contrast than conventional subtraction. For the first time, positive contrast imaging of transplanted human PIs was performed in vivo in patients.

Conclusion

The proposed method allows 3D data acquisition within a single breath-hold and yields enhanced contrast-to-noise ratios of transplanted SPIO labeled pancreatic islets relative to negative contrast images, therefore providing improved identification.     

Assessment of Slovak population exposure to lead

Exposure of the Slovak Republic population to lead from food and drinks was studied. Calculations were done using 150,000 food, plant and animal raw materials, and drinks sampled in 1986–2002. Estimates of exposure to lead from actual and model consumption patterns were calculated for an average inhabitant and compared with the provisional tolerable weekly intake (PTWI) value. Existing knowledge and experience from projects run since 1991, as well as information from the database of the Centre for Evaluation of Contaminant Occurrence, located at the Food Research Institute in Bratislava, were utilized. The estimated exposure of the population to lead seems to be persistently low with a tendency to a slight decrease, especially in recent years. The exposure doses estimated for the last 6 years using the mean and median values show that the weekly intake of lead from food and drinks represents 22.3 to 14.1% PTWI and 12.2 to 7.2% PTWI, respectively.     

Satureja horvatii essential oil: In vitro antimicrobial and antiradical properties and in situ control of Listeria monocytogenes in pork meat

The dominant compounds in Satureja horvatii oil were p-cymene (33.14%), thymol (26.11%) and thymol methyl ether (15.08%). The minimum inhibitory concentration (MIC) varied from 0.03 to 0.57 mg/mL for bacteria, and from 0.56 to 2.23 mg/mL for yeast strains, while minimum bactericidal/yeast-cidal concentration (MBC/MYC) varied from 0.07 to 1.15 mg/mL and 1.11 to 5.57 mg/mL for bacteria and yeasts, respectively. The antiradical potential of the essential oil was evaluated using hydroxyl radical (•OH) generated in Fenton reaction. The meat preserving potential of essential oil from Satureja horvatii was investigated against L. monocytogenes. Essential oil successfully inhibited development of L. monocytogenes in pork meat. Sensorial evaluation on flavor and color of meat was performed. The color and flavor of meat treated with essential oil improved after 4 days of storage. S. horvatii essential oil can act as a potent inhibitor of food spoiling microorganisms, in meat products and also can be a useful source of natural antioxidants.