Effect of stress corrosion cracking at various strain rates on the electrochemical corrosion behavior of Mg-Zn-In-Sn alloy

This study is aimed to determine the effect of stress corrosion with low strain rates on the electrochemical properties of alloy electrode. Stress corrosion cracking tests of Mg-Zn-In-Sn alloy in 3.5 wt.% sodium chloride solutions at 25℃ were performed. The effects of the electrochemical properties under the stress corrosion with low strain rates were investigated. The microstructures of cross section were observed by optical microscope. The results showed that the ultimate tensile strengths of Mg-Zn-In-Sn alloy increased and the strain decreased as the strain rates increased. Open circuit potentials (OCP) of Mg-Zn-In-Sn alloy electrode possess stability and the loop currents (LC) were improved with the increasing of stress in the elastic zone. The variation of OCP and LC did not change with the increasing of strain-rate. The microstructure of cross section observing revealed the mechanism of OCP and LC changing.     

Influence of MBBR carrier geometrical properties and biofilm thickness restraint on biofilm properties, effluent particle size distribution, settling velocity distribution, and settling behaviour

The relatively poor settling characteristics of particles produced in moving bed biofilm reactor (MBBR) outline the importance of developing a fundamental understanding of the characterization and settleability of MBBR-produced solids. The influence of carrier geometric properties and different levels of biofilm thickness on biofilm characteristics, solids production, particle size distribution (PSD), and particle settling velocity distribution (PSVD) is evaluated in this study. The analytical ViCAs method is applied to the MBBR effluent to assess the distribution of particle settling velocities. This method is combined with microscopy imaging to relate particle size distribution to settling velocity. Three conventionally loaded MBBR systems are studied at a similar loading rate of 6.0 g/(m² •day) and with different carrier types. The AnoxK™ K5 carrier, a commonly used carrier, is compared to so-called thickness-restraint carriers, AnoxK™ Z-carriers that are newly designed carriers to limit the biofilm thickness. Moreover, two levels of biofilm thickness, 200 μm and 400 μm, are studied using AnoxK™ Z-200 and Z-400 carriers. Statistical analysis confirms that K5 carriers demonstrated a significantly different biofilm mass, thickness, and density, in addition to distinct trends in PSD and PSVD in comparison with Z-carriers. However, in comparison of thickness-restraint carriers, Z-200 carrier results did not vary significantly compared to the Z-400 carrier. The K5 carriers showed the lowest production of suspended solids (0.7 ± 0.3 g-TSS/day), thickest biofilm (281.1 ± 8.7 µm) and lowest biofilm density (65.0 ± 1.5 kg/m³). The K5 effluent solids also showed enhanced settling behaviour, consisting of larger particles with faster settling velocities.     

Injuries and risk-taking behaviours in Portuguese adolescents: Highlights from the health behaviour in school-aged children survey

Aim

Injuries in adolescence are an important public health problem and a major cause of morbidity and mortality in this age group. This study aimed to determine the behaviour profile associated to risk of injury and the differences between genders, region and ethnic origin.

Methods

A cross-sectional study design of a nationally representative sample of 1581 adolescents of the Portuguese Health Behaviour in School-Aged Children study.

Results

An occurrence of one injury-related event in the previous year was reported by 21.4% of the respondents and 5.9% referred having more than one injury-related event. Boys reported higher frequency of those events when compared to girls, and non-Portuguese subjects referred higher frequency of events. Scoring higher in violence-related behaviour and psychosomatic complaints was associated to higher chances of referring more than one injury-related event.

Conclusion

Gender, social background and behaviour profile are factors that seem to influence the risk of injuries. This information should guide those involved in the planning of injuries prevention programs in youth.     

The influence of place attachment, and moral and normative concerns on the conservation of native vegetation: A test of two behavioural models

This study examines the influence of place attachment, values, beliefs and personal norms about environmental action on the conservation of native vegetation in two primary production settings in South Australia. We use regression and multiple mediation analyses to test a base model of pro-environmental behaviour which includes variables from value-belief-norm (VBN) theory and then compare it to an expanded model which includes the same variables and five dimensions of place attachment. The expanded model including place attachment explained up to twice the amount of variance in native vegetation planting than the base model when controlling for all variables preceding behaviour, but the overall explanatory power was low (<22%). Place attachment had a stronger influence on the antecedents of behaviour compared with the behaviour itself, particularly nature bonding which was a significant moderate predictor of both personal norms and awareness of consequences in the two study regions. We assert that place attachment has statistically significant direct and indirect effects on variables included in VBN theory. Future studies may reveal stronger effects in settings where there are fewer resource and monetary costs associated with pro-environmental behaviour.     

Prediction of metal-adsorption behaviour in the remediation of water contamination using indigenous microorganisms

In recent years, the adsorption of heavy metal cations onto bacterial surfaces has been studied extensively. This paper reports the findings of a study conducted on the heavy metal ions found in mine effluents from a mining plant where Co²⁺ and Ni²⁺ bearing minerals are processed. Heavy metal ions are reported to be occasionally present in these mine effluents, and the proposed microbial sorption technique offers an acceptable solution for the removal of these heavy metals. The sorption affinity of microorganisms for metal ions can be used to select a suitable microbial sorbent for any particular bioremediation process. Interactions of heavy metal ions (Co²⁺ and Ni²⁺) and light metal ions (Mg²⁺ and Ca²⁺) with indigenous microbial cells (Brevundimonas spp., Bacillaceae bacteria and Pseudomonas aeruginosa) were investigated using the Langmuir adsorption isotherm, pseudo second-order reaction kinetics model and a binary-metal system. Equilibrium constants and adsorption capacities derived from these models allowed delineation of the effect of binding affinity and metal concentration ratios on the overall adsorption behaviour of microbial sorbents, as well as prediction of performance in bioremediation systems. Although microbial sorbents used in this study preferentially bind to heavy metal ions, it was observed that higher concentrations (>90 mg/?) of light metal ions in multi-metal solutions inhibit the adsorption of heavy metal ions to the bacterial cell wall. However, the microbial sorbents reduced Ni²⁺ levels in the mine-water used (93–100% Ni²⁺ removal) to below the maximum acceptable limit of 350 μg/?, established by the South African Bureau of Standards. Competition among metal ions for binding sites on the biomaterial surface can occur during the bioremediation process, but microbial sorption affinity for heavy metal ions can enhance their remediation in dilute (<5 mg/? heavy metal) wastewaters.     

Using a fire propagation model to assess the efficiency of prescribed burning in reducing the fire hazard

We examined how fire hazard was affected by prescribed burning and fuel recovery over the first six years following treatment. Eight common Mediterranean fuel complexes managed by means of prescribed burning in limestone Provence (South-Eastern France) were studied, illustrating forest and woodland, garrigue and grassland situations. The coupled atmosphere-wildfire behaviour model FIRETEC was used to simulate fire behaviour (ROS, intensity) in these complex vegetations. The temporal threshold related to the effectiveness of prescribed burning in reducing the fire hazard was assessed from derivated fuel dynamics after treatment. The study showed that prescribed burning treatment was effective for the first two years in most of the Mediterranean plant communities analysed. Thereafter, all forests and shrublands were highly combustible with a fire line intensity of more than 5000 kW/m except for pine stands with or without oak (medium intensity of 2000 kW m⁻¹ 3 years after treatment). Low fire line intensity (900 kW m⁻¹) was obtained for grassland which was entirely treatment-independent since the resprouter hemicryptophyte, Brachypodium retusum, is highly resilient to fire. Fire behaviour was greatly affected by fuel load accumulation of Quercus ilex in woodland, and by standing necromass of Rosmarinus officinalis in treated garrigue. Pure pine stands with shrub strata similar to garrigue showed a lower fire intensity due to wind speed decrease at ground level under tree canopy, underlining the advantage of maintaining a proportion of canopy cover in strategic fuel-break zones.     

Hearing Protectors: Topicality and Research Needs

Occupational noise specialists do not generally recommend hearing protection devices (HPDs) as a preferred solution to noise risk prevention. Nevertheless, these devices are widely used and are in fact often necessary. Selection of an HPD should take into account comfort and the capacity for perceiving external signals, when they are worn. Current European regulations require that HPD attenuation be considered, when comparing noise exposure to limit values. However, HPD attenuation is effectively unknown under real-world conditions. Some methods are designed to give approximate attenuation values and these provide results within a wide statistical range. Field measurement methods and current standards have been developed to deal with this situation. The specific characteristic of impulse noise requires establishment of dedicated criteria and tools for HPD selection and testing. This paper introduces a number of avenues for research, which could be of assistance in improving HPD selection, qualification and design.     

Investigation and identification of factors affecting migrating peasant workers’ usage of safety footwear in the Chinese construction industry

A sample of 300 migrating peasant workers from 15 Chinese building construction sites completed a demographic questionnaire to investigate the usage of safety footwear. The survey form was constructed based on the theory of planned behaviour, and a total of 12 questions focusing on the workers’ past experience, attitudes, subjective norms and perceived behavioural control were included in the survey. It was found that 92% of the participants did not wear safety footwear while working on construction sites, although more than 91% of them believed that safety footwear would protect the foot from injury; none of the participants had been provided free safety footwear by their employer. Regression analysis shows that employers’ attitude is the most important factor affecting their usage of safety footwear, ‘providing free safety footwear’ and ‘comfortability of the safety footwear’ ranking second and third respectively.     

Best practice measures assessment for construction and demolition waste management in building constructions

Currently the construction and demolition (C&D) waste collection system in Spain is managed in a decentralized manner by each sub-contracted company. This lack of comprehensive strategy for C&D waste management causes a confusing and sometimes individual attitude regarding the different measures for C&D waste. Therefore effective waste management should be enforced. Construction stakeholders have wide range of best practices in C&D waste management that can be implemented, so they need to be assessed for their effectiveness.The aim of this research study is to assist construction stakeholders in making a decision on C&D waste management. This paper carries out a survey conducted among the construction agents in order to evaluate the effectiveness of 20 best practice measures regarding C&D waste management, identifying the most suitable types of building constructions to implement these practices and also the advantages and drawbacks of their performance in a building construction project.Results of this study show that among the highly effective best practices are: the use of industrialized systems and the contract of suppliers managing the waste. In addition, distributing small containers in the work areas is also another high valued practice, although only 36% of respondents usually implement this measure in their works.     

阻燃纯棉织物的研究与发展

对阻燃纯棉织物的国内外研究现状、生产和应用中存在的问题，进行了论述，并提出了今后的发展方向