Chelation-photoelectric concept for fire detection

An exploratory study has been made of the adsorption of incipient combustion gases on metal surfaces and organic metal chelate coated metal surfaces. Data obtained in this study suggest that a smoke or fire detection system could be based on the adsorption-photoelectric effects observed. IIT Research Institute Note: This work was supported by the National Science Foundation, Washington, DC, through Contract No. NSF-C76-10255.     

A study of cooling water requirements for the protection of metal surfaces against thermal radiation

Among the hazards posed to storage tanks by thermal radiation are the effects of changes in the mechanical strength of the metal at high temperatures that may lead ultimately to failure. Alarge-scale experimental study has been made of the water cooling requirements for metal surfaces exposed to thermal radiation. A two meter square radiation furnace and commercial water spray equipment were used in the study, which included trials on both vertical and inclined target surfaces. Water application rates between 1.4 and 10.4 L/min per square meter and incident heat fluxes up to 70 kW per square meter were employed. The experimental work was supported by a theoretical model of the cooling process.The results indicate that a metal plate, exposed to a nearby radiating source, can be kept below the temperature at which its mechanical properties become impaired as long as a water film, of minimal thickness, can be maintained over it.     

Effects of coefficients of solar reflectivity and infrared emissivity on the temperature and heat flux of horizontal flat roofs of artificially conditioned nonresidential buildings

Nonresidential buildings such as shopping centers, supermarkets and factories are constructions characterized as having large roof surfaces in comparison to their external wall surfaces. When conditioned artificially, these buildings become great consumers of electricity. To reduce this consumption, insulation materials are usually used. Notwithstanding the effectiveness of such a procedure, both the cost and environmental issues (the heat-island effect) have been considered as limiting factors for its usage. In this study, we analyze the effect of the application of selective coatings (with very high reflectance for solar radiation and high emittance for infrared radiation) on the surface temperature of the roof and the heat flux that crosses it. Two roof concepts were considered, namely metal roofs both with and without conventional mass-insulation, i.e. an insulating board on the internal side or between two metal foils. The methodology adopted to solve the proposed problem was based on the heat transfer analysis of a roof composed of multiple layers. External air temperature and solar radiation are considered time-varying. The results obtained show the benefits of selective coatings in terms of reductions in both roof temperature and heat flux and, consequently, alleviation of the urban heat-island effect and reduction of electricity consumption.     

Microbial biosorption of copper and lead from aqueous systems

Biosorption of metal ions from aqueous systems was evaluated using a culture of acioic soil isolates grown in a completely mixed, aerobic, semi-batch culture reactor. The laboratory scale system was used to test single and bimetallic solutions of copper and lead with sulfates, chlorides, or nitrates. To elucidate the key factors influencing biosorption and to characterize metal uptake by cellular and extra cellular components of the microbial system, a dialysis testing procedure was developed. A direct contact technique was used to determine the rate of metal sorption on cellular surfaces. The effectiveness of biosorption was influenced by pH, initial metal concentrations, and anionic composition. Respirometric tests were carried out to identify potential inhibitory effects of metal accumulation on microbial oxygen uptake rates.     

变形链球菌在几种不同合金表面的黏附实验研究

目的：比较在相同培养条件下,变形链球菌在5种临床常用合金材料（镍铬合金、钴铬合金、金钯合金、74％金合金、86％金合金）表面的黏附情况。方法将5种合金、材料的试件（各5个）逐级打磨、抛光至粗糙度无差异,灭菌后分别置于含有变形链球菌的培养基内厌氧培养,48 h 后检测试件表面菌落生长数量。结果合金材料表面黏附的变形链球菌量：镍铬合金＞钴铬合金＞金钯合金＞74％金合金＞86％金合金。74％金合金组与86％金合金组间变形链球菌量差异无统计学意义（P ＞0．05）,其余各组间差异均有统计学意义（P ＜0．05）。结论贵金属修复体在控制变形链球菌黏附方面优于普通合金修复体,临床上可考虑尽量选用贵金属材料进行修复。     

Lead,iron, chromium and zinc in road runoff at Pullman,Washington

The inputs of iron, lead, chromium and zinc to a 0.6 acre road surface were investigated. The selection of a viaduct in Pullman, Washington as a study area permitted the exclusion of metal input from non-road surfaces. Dust and precipitation metal deposition rates were measured at the viaduct as well as at a control location. It was found that the primary source of metals at the road surface was the operation of motor vehicles. For three separate storm events, runoff samples were collected, flow was measured and runoff samples were analyzed for total solids, total metals and dissolved-colloidal metals. Less than 5 percent of each metal in the runoff samples existed in the dissolved-colloidal fraction. Mean concentrations of total metals in road runoff were 1.86, 89, 0.139 and 19.1 mg/l for Pb, Fe, Cr, and Zn, respectively. A mathematical model was developed allowing the estimation of metal loadings for a storm event typical of the area, given the total runoff volume for the particular storm event. It was also found that a residual amount of metals remains on the road surface after each storm.     

Fungi in a heavy metal precipitating stream in the Mansfeld mining district, Germany

Fungal growth on alder leaves was studied in two heavy metal polluted streams in central Germany. The aim of the study was to examine previously observed differences in leaf decomposition rates, heavy metal precipitation and fungal involvement in these processes at the microscopic level. Ergosterol analyses indicated that neither habitat was optimal for fungi, but leaves exposed at the less polluted site (H8) decomposed rapidly and were colonized externally and internally by fungi and other microorganisms. Leaves exposed at the more polluted site (H4) decomposed very slowly and fungal colonization was restricted to external surfaces. An amorphous organic layer, deposited within 24 h of exposure, quickly became covered with a pale blue-green crystalline deposit (zincowoodwardite) with significant amounts of Al, S, Cu and Zn, determined by energy dispersive X-ray spectroscopy (EDS). Scanning electron microscopy (SEM) analysis of the precipitate revealed a branching arrangement of the precipitated particles caused by the presence of fungal hyphae growing on the surface. Hyphae that were not disturbed by handling were usually completely encased in the precipitate, but hyphae did not contain EDS-detectable amounts of precipitate metals. Elemental analysis using inductively coupled plasma (ICP) atomic emission spectrometry and ICP mass spectrometry revealed continuing accumulation of Zn, Cu and several other metals/metalloids on and in leaves. The formation of metal precipitates on various artificial substrates at site H4 was much reduced compared to leaves, which we attribute to the absence of fungal colonization on the artificial substrates. We could not determine whether fungi accelerate the precipitation of heavy metals at site H4, but mycelial growth on leaves continues to create new surfaces and therefore thicker layers of precipitate on leaves compared to artificial substrates.     

Experimental study on low cycle fatigue strength of beam-to-column connections in steel bridge bents with different plate assembling and material mismatching

This study examined the effects of inherent defects due to plate assembling and material mismatched condition between base and weld metal on the fatigue strength of beam-to-column connections. Low cycle fatigue tests were carried out on specimens with different plate assembling systems and material mismatched conditions. The test results revealed that the global load-displacement relationships from specimens with different plate assembling systems and material mismatched conditions are similar, meaning these effects involve only local behavior of specimens. However, the fatigue strength of the specimens strongly depends on the location of defects resulting from plate assembling and mismatched conditions. The specimen with the undermatched conditions and the existing defect located closer to the corner of beam-to-column connection tends to have lower fatigue strength. The fracture surfaces indicated that failure patterns of specimen are different regarding mismatched conditions. While the crack propagated through the weld metal for the undermatched condition, it propagated towards the boundary between base and weld metal for overmatched condition. Elasto-plastic shell analysis was performed under the same condition as the experiments. And it is found that when evaluating fatigue strength of beam-to-column connections, the effects of plate assembling system and material mismatched condition should be considered.     

一种新型的夹芯结构

金属（铝壳,蜂房或金属泡沫核）或聚合物（复合面层,聚合物泡沫核）夹芯结构被认为是承受弯曲荷载的优化设计结构。本文在发挥金属性材料和聚合物材料优势的基础上,研制了一种新的混杂夹芯结构。这种新理念的结构中金属片用在外表面以加强刚度,轻质核与外壳粘结成整体。此外,还将复合层或木材层作为中间层以提高冲击阻力。制造这种新结构潜在的方法是基于真空压缩。对该结构的研究包含基于有限元分析的几种面层的理论构造,改进的简化方程,对典型案例的试验。     

Failures after sun exposure

At the Stockholm meeting of CIB commission W56 last year, this paper was presented by an executive of the Swedish firm Korrugal. It concerned the delamination of some metal‐skin panels — not those of this company — after exposure to sunlight and high temperatures; dark surfaces fared worse than light colours. The likeliest reason was the actual method of fabrication, for which further study and perhaps regulatory control should be welcomed, it is suggested.     

Determination of iron colloid size distribution in the presence of suspended cells: Application to iron deposition onto a biofilm surface

Transport and deposition of colloidal Fe, Mn and Al oxides play key roles in the cycling of toxic transition metals in aquatic environments because these colloids strongly bind transition metals. Further, attachment of biological cells and biofilm growth on surfaces can indirectly affect toxic metal distribution by influencing the deposition of colloidal oxides to surfaces. To elucidate the mechanisms governing these processes, deposition of colloidal oxides onto surfaces must be evaluated in the presence of suspended and adherent bacterial cells. Both particle size and concentration are expected to influence deposition. An experimental protocol was developed to determine the size distribution of iron colloids in mixtures with suspended cells. A Ti(III) reagent was used to reduce and dissolve colloidal Fe(III) from mixtures containing both suspended cells and Fe colloids. The size distribution of Fe(III) colloids in the original solution was then determined from the difference between size distributions before and after dissolution of Fe with Ti(III). The Ti(III) reagent dissolved over 95% of the Fe colloids without altering the size distribution of suspended bacterial cells, and the method accurately determined the size distribution of Fe colloids added to cell suspensions. The applicability of this protocol was tested by applying it to a study of the deposition of Fe(III) oxide particles onto glass surfaces with and without biofilms of the bacterium Burkholdaria cepacia 17616. Experimental results using a laboratory biofilm reactor indicated that the deposition rate of Fe(III) colloids was not significantly affected by the presence of B. cepacia biofilms or by the presence of previously deposited Fe. However, deposition of Fe to reactor surfaces other than the glass surfaces may have interfered with the analyses, and atomic absorption measurements showed a slight increase in Fe deposition onto glass surfaces with biofilms present. Fe deposition to the composite of all reactor surfaces increased with increasing colloidal particle size, indicating a dominance of interception and/or sedimentation in controlling Fe deposition on surfaces in the biofilm reactor.     

Ultrafine particles from electric appliances and cooking pans: experiments suggesting desorption/nucleation of sorbed organics as the primary source

Ultrafine particles are observed when metal surfaces, such as heating elements in electric appliances, or even empty cooking pans, are heated. The source of the particles has not been identified. We present evidence that particles >10 nm are not emitted directly from the heating elements or the metal surfaces. Using repeated heating of an electric burner, several types of cooking pans, and a steam iron, the increase in the number of particles (>10 nm) can be reduced to 0. After the devices are exposed to indoor air for several hours or days, subsequent heating results in renewed particle production, suggesting that organic matter has sorbed on their surfaces. Also, after a pan has been heated to the point that no increase in particles is observed, washing with detergent results in copious production of particles the next time the pan is heated. These observations suggest that detergent residue and organics sorbed from indoor air are the sources of the particles. We hypothesize that organic compounds are thermally desorbed from the hot surface as gaseous molecules; as they diffuse from the hot air near the pan into cooler air, selected compounds exceed their saturation concentration and nucleation occurs.     

Study of large elastic deflections of a thin sheet

The aim of the present investigation is to study the ‘blending band’ in-between two non-conforming cylindrical surfaces imposed on a planar thin elastic metal sheet. Initially, an experimental investigation was made over all the sheet, in order to make a survey of the bending and membrane stress and strain fields, principal curvatures, bending and membrane strain energy densities.

Secondly, a rational explanation was sought for the most important experimental results collected. In view of the obvious analytical difficulties involved in such an attempt, a simple geometrical approach was adopted. Under the limitations of a preliminary study, the expressions for some geometrical parameters and for the bending and membrane energies thus obtained, lead to results compatible with the experimental data.     

Development of multimetal binding model and application to binary metal biosorption onto peat biomass

Biosorption of Cr(3+), Cu(2+) and Cd(2+) from binary metal solutions onto peat in the batch systems was investigated at pH 4. The order of maximum uptake was Cr>or=Cu>Cd and maximum uptake levels of ca. 0.4 mmol/g were observed for chromium and copper while cadmium was taken up to a maximum of ca. 0.2 mmol/g. Co-ion competition resulted in up to 70 percent decrease of primary metal uptake. A novel approach to multicomponent sorption modelling involving regression to the total metal taken up was adopted. Two extended Langmuir-type models were found to exhibit good fit to the experimental data. Using the simpler model of these, three-dimensional sorption surfaces were generated which describe the metal uptake as a function of equilibrium concentrations of both metals. These methods allow prediction of metal uptakes over a continuum of concentrations of both metals in binary systems.     

考虑焊接热影响区软化的高强钢对接接头强度

为研究焊接热输入对调质态高强钢对接焊缝接头强度的影响,设计了对接焊缝接头的静力拉伸试验,进行了对接接头熔敷金属及热影响区(HAZ)硬度分布测试,并对影响接头强度的关键因素进行了参数分析。试验材料选取Q550和Q690两种调质态高强钢,采取气体保护焊分别以1.0、1.5kJ/mm和2.0kJ/mm三个等级焊接热输入,以涵盖常用焊接工艺参数。静力拉伸试验结果表明：对接焊缝接头的强度随焊接热输入的增大而下降;在焊接热输入1.0kJ/mm下,接头的破坏模式为母材处断裂,而在热输入1.5kJ/mm和2.0kJ/mm下,接头断裂均发生在热影响区处。通过硬度分布测试发现,接头的热影响区存在硬化区和软化区。随着热输入的增加,接头软化区范围增大、最小硬度下降,导致接头强度降低。静力拉伸试验的强度测试结果与硬度分布测试结果在宏观上相互印证。参数分析结果表明,热影响区中软化区与母材强度之比、相对软化宽度是决定接头强度的主要因素,且其与接头强度呈近似线性相关关系。     

Improvement of metal adsorption onto chitosan/Sargassum sp. composite sorbent by an innovative ion-imprint technology

Technology for immobilization of biomass has attracted a great interest due to the high sorption capacity of biomass for sequestration of toxic metals from industrial effluents. However, the currently practiced immobilization methods normally reduce the metal sorption capacities. In this study, an innovative ion-imprint technology was developed to overcome the drawback. Copper ion was first imprinted onto the functional groups of chitosan that formed a pellet-typed sorbent through the granulation with Sargassum sp.; the imprinted copper ion was chemically detached from the sorbent, leading to the formation of a novel copper ion-imprinted chitosan/Sargassum sp. (CICS) composite adsorbent. The copper sorption on CICS was found to be highly pH-dependent and the maximum uptake capacity was achieved at pH 4.7-5.5. The adsorption isotherm study showed the maximum sorption capacity of CICS of 1.08 mmol/g, much higher than the non-imprinted chitosan/Sargassum sp. sorbent (NICS) (0.49 mmol/g). The used sorbent was reusable after being regenerated through desorption. The FTIR and XPS studies revealed that the greater sorption of heavy metal was attributed to the large number of primary amine groups available on the surfaces of the ion-imprinted chitosan and the abundant carboxyl groups on Sargassum sp. Finally, an intraparticle surface diffusion controlled model well described the sorption history of the sorbents.     

Carbon and nitrogen stable isotopes and metal concentration in food webs from a mining-impacted coastal lagoon

Two food webs from the Mar Menor coastal lagoon, differing in the distance from the desert-stream through which mining wastes were discharged, were examined by reference to essential (Zn and Cu) and non-essential (Pb and Cd) metal concentrations and stable isotopes content (C and N). The partial extraction technique applied, which reflects the availability of metals to organisms after sediment ingestion, showed higher bioavailable metal concentrations in sediments from the station influenced by the mining discharges, in agreement with the higher metal concentrations observed in organisms, which in many cases exceeded the regulatory limits established in Spanish legislation concerning seafood. Spatial differences in essential metal concentrations in the fauna suggest that several organisms are exposed to metal levels above their regulation capacity. Differences in isotopic composition were found between both food webs, the wadi-influenced station showing higher delta(15)N values and lower delta(13)C levels, due to the discharge of urban waste waters and by the entrance of freshwater and allochthonous marsh plants. The linear-regressions between trophic levels (as indicated by delta(15)N) and the metal content indicated that biomagnification does not occur. In the case of invertebrates, since the "handle strategy" of the species and the physiological requirements of the organisms, among other factors, determine the final concentration of a specific element, no clear relationships between trophic level and the metal content are to be expected. For their part, fish communities did not show clear patterns in the case of any of the analyzed metals, probably because most fish species have similar metal requirements, and because biological factors also intervened. Finally, since the study deals with metals, assumptions concerning trophic transfer factors calculation may not be suitable since the metal burden originates not only from the prey but also from adsorption over the body surfaces and seawater ingestion.     

The effect of corrosion defects on the burst pressure of pipelines

The loss of metal in a pipeline due to corrosion usually results in localized pits with various depths and irregular shapes on its external and internal surfaces. The effect of external corrosion defects was studied via a series of small-scale experiments and through a nonlinear numerical model based on the finite element method. After calibration was conducted, based on the experimental results, the model was used to determine the burst pressure as a function of material and geometric parameters of different pipes and defects. This paper briefly summarizes these results, which are subsequently used to develop a simple procedure for estimating the burst pressure of corroded pipes.     

Understanding the physical processes of pollutant build-up and wash-off on roof surfaces

Pollutants originating with roof runoff can have a significant impact on urban stormwater quality. This signifies the importance of understanding pollutant processes on roof surfaces. Additionally, knowledge of pollutant processes on roof surfaces is important as roofs are used as the primary catchment surface for domestic rainwater harvesting. In recent years, rainwater harvesting has become one of the primary sustainable water management techniques to counteract the growing demand for potable water.This paper presents the outcomes of an in-depth research study into particulate matter build-up and wash-off for roof surfaces. In this research, particulate matter was considered as the indicator pollutant where the processes related to other pollutants can be predicted based on the understanding generated for particulate matter. The study outcomes confirm that the build-up process on roof surfaces is comparatively similar to road surfaces. However, particle loads collected from roofs were significantly less compared to road surfaces and much finer in texture. Wash-off from roofs also showed significant similarities to wash-off from roads. A relatively high concentration of particulate matter was noted during the initial part of storm events. Furthermore, the amount of particulate matter remaining on the roof surfaces was significantly high for less intense rain events.     

The Milgo experiment: an interview with Haresh Lalvani

For just less than a decade, Haresh Lalvani has been working on a series of projects with Milgo/Bufkin, a leading architectural metal-fabrication company, seeking to economically integrate the shaping and making of metal surfaces into elements that create a seamless whole. Here, John Lobell interviews Lalvani about his pioneering work with computer-aided design and manufacturing and how it has been informed by his development of the Morphological Genome, a universal code for mapping and manipulating form, whether natural or man-made. Copyright © 2006 John Wiley & Sons, Ltd.