Search results

The purpose of this paper is to examine naturally occurring episodes of aggressive interaction among adolescents in residential correctional programmes. The aims of our study were twofold. First, the development of a new camera-glasses method, and second, the method's applicability in the study of aggressive adolescents in residential care.

Based on a mobile assessment strategy, the paper developed a new methodology for in-the-field recording of environmental conditions in which aggressive behaviour arises. The authors used glasses with an inbuilt camera worn by research subjects to record observational data. In the particular study presented here the authors used camera-glasses to observe the material and social environments of eight aggressive adolescents in a residential treatment programme and of a contrast group of four non-aggressive adolescents living at home.

The crucial methodological findings are that camera-glasses successfully record the social and physical environments of aggressive adolescents from their perspective in relation to their environment and interlocutors, and that the camera-glasses method does not generate high reactivity. The results show that aggressive adolescents in residential care use direct and reactive forms of aggression, and that their aggressive behaviours occur predominantly in settings with limited adult supervision. In residential care aggressive behaviour is, paradoxically, an effective strategy for individuals to gain regard and social status among peers and to push their interests among staff.

An obvious limitation is the reliance on a small sample which limits the generalisation of the results.

For residential facilities it is crucial to reduce the occurrence of low supervised social situations in order to minimise peer contagion. Furthermore, staff and educators need to be trained to use deescalating response strategies when dealing with adolescents’ aggressive behaviour, precisely deescalating strategies which neither involve acquiescence nor surrender to pressure.

Our investigations demonstrate that the camera-glasses method is a promising new assessment technique which has applicability in various fields of adolescent research.

The General Aggression Model (GAM) by Anderson & Bushman (2002) reveals the great depth of research on internal processes. Research on naturally occurring aggressive interaction episodes in specific material and social environments, however, is still largely lacking. How can information about environmental requirements and social processes relevant to aggression be acquired methodically? Based on an ambulatory assessment strategy, we discuss various apparatus‐based and direct observation strategies. Finally, we introduce an innovative methodology for recording in the field the environmental conditions in which aggressive behaviour arises, using the technical device of glasses with an inbuilt camera. Our investigations so far show that the camera‐glasses method is a promising new data collection technique that can be applied fruitfully in various fields of aggression research.

Important reserves of oil and gas, which are left to be discovered and produced, are mainly concentrated in challenging locations and under severe conditions such as high pressure (HP)/high temperature (HT). The presence of aggressive environments including H₂S, CO₂ and chlorides plus HP/HT causes a series of corrosion problems, which cost the oil industry billions of dollars a year. Thus, there is an increasing challenge for tubes (i.e. oil country tubular goods, for short, OCTG) used in producing oil and gas. The purpose of this study is to summarize different kinds of corrosion problems and their mitigation, to more efficiently protect OCTG from corrosion.

To effectively select proper mitigation methods, the mechanism of corrosion must be understood, which can be classified into four categories: sweet corrosion, sour corrosion, galvanic corrosion and microbiologically induced corrosion. Also, the effects of environmental and material factors on the corrosion rate are presented. Subsequently, current technology of mitigating these corrosion problems has been discussed, including the development of materials, application of chemical inhibitors and application of protective layers.

It is stressed that limits exist for each individual mitigation method; therefore, a careful balance between economic life of OCTG and safety in operation is required.

The main purpose of this essay is to give a brief review and detailed introduction and analysis about those technologies.

Several process stages in the pulp and paper industry are undergoing changes. This is done partly for optimization, and partly to discontinue the use of substances hazardous to the environment. A side effect of these measures is that the problem of corrosion has increased. Explains why certain environments in the pulp and paper industry represent corrosion risks, with some examples given of corrosion failures, and suggests appropriate materials for these process stages.

The purpose of this paper is to evaluate the performance of polypropylene glycol (PPG), as a corrosion inhibitor for aluminium corrosion in 0.5 M H₂SO₄ solution at 303-333 K and the effect of addition of iodide ions on the corrosion inhibition efficacy of PPG.

The corrosion inhibition performance of PPG alone and on addition of iodide ions in the acid medium was evaluated using weight loss and electrochemical [electrochemical impedance spectroscopy (EIS), linear polarisation resistance (LPR) and potentiodynamic polarization (PDP)] methods as well as surface analysis approach at 303-333 K. The morphology of the corroding aluminium surface without and with the additives was visualised using scanning electron microscopy (SEM). The trend of inhibition efficiency with temperature was used to propose the mechanism of inhibition and type of adsorption.

Results obtained showed that PPG moderately retarded the corrosion of Al in 0.5 M H₂SO₄ solution. Addition of KI to PPG is found to synergistically improve the inhibitive ability of PPG. From the variation of inhibition efficiency, K_ads, and E_a, with rise in temperature, physisorption mechanism is proposed for the adsorption of PPG and PPG + KI onto the Al surface in 0.5 M H₂SO₄ solution. Polarisation results showed that PPG and PPG + KI acted as mixed type inhibitor. The adsorption of PPG and PPG + KI, respectively, onto the metal surface followed El-Awady et al. adsorption isotherm model. SEM and water contact angle analysis confirmed the adsorption of PPG and PPG + KI on Al surface.

The research is limited to aqueous acid environment in aerated condition, and all tests were performed under static conditions.

The use of PPG as corrosion inhibitor for Al corrosion in acidic medium were reported for the first time. The results suggest that iodide ions could be used to enhance corrosion protection ability of PPG which could find practical application in corrosion control in aqueous acidic environment. The data obtained would form part of database on the synergistic effect of iodide ions addition to polymer to control acid-induced corrosion of metal.

The use of PPG as corrosion inhibitor for Al corrosion in acidic medium were reported for the first time. The results suggest that iodide ions could be used to enhance corrosion protection ability of PPG which could find practical application in corrosion control in aqueous acidic environment. The data obtained would form part of database on the synergistic effect of iodide ions addition to polymer to control acid-induced corrosion of metal.

In tomorrow's world there will be more attention paid to the conservation of materials and energy. Energy is often a significant input in the production of materials. A greater realisation of the degradation mechanisms (and particularly corrosion) must be achieved in that corrosion is ‘an insidious consumer of our stocks of raw materials, a squanderer of our productive capacity and a dissipator of the fruits of our labours’. In real terms it costs about 4 per cent of the GNP of the UK, USA, or Japan and this is wasted ‘labour’. Another way of looking at these figures is to remember that a third of all the steel produced in the UK in one year goes to back to rust within the year.

Performance of the structure depends on design, construction, environment, utilization and reliability aspects. Other factors can be controlled by adopting proper design and construction techniques, but the environmental factors are difficult to control. Hence, mostly in practice, the environmental factors are not considered in the analysis and design appropriately; however, their impact on the performance of the structures is significant along with the design life. It is in this light that this paper aims to perform the time-dependent performance analysis of reinforced concrete structures majorly considering environmental factors.

To achieve the intended objective, a simply supported reinforced concrete beam was designed and detailed as per the Euro Code (EC2). The time-dependent design parameters, corrosion parameters, creep and shrinkage were identified through thorough literature review. The common empirical equations were modified to consider the identified parameters, and finally, the time-dependent performance of reinforced concrete beam was performed.

Findings indicate that attention has to be paid to appropriate consideration of the environmental effect on reinforced concrete structures. In that, the time-dependent performance of reinforced concrete beam significantly decreases with time due to corrosion of reinforcement steel, creep and shrinkage.

However, the Euro code, Ethiopian code and Indian code threat the exposure condition of reinforced concrete by providing corresponding concrete cover that retards the corrosion initiation time but does not eliminate environmental effects. The results of this study clearly indicate that the capacity of reinforced concrete structure degrades with time due to corrosion and creep, whereas the action on the structure due to shrinkage increases. Therefore, appropriate remedial measures have to be taken to control the defects of structures due to the environmental factors to overcome the early failure of the structure.

The purpose of this study is to improve the surface electrical conductivity and corrosion resistance of AISI430 stainless steel (430 SS) as bipolar plates for direct formic acid fuel cell (DFAFC).

The niobium diffusion layers have been successfully synthesized on 430 SS substrate by the plasma surface diffusion alloying technique under different diffusion alloying time.

The surface morphology of Nb-modified 430 SS prepared under the diffusion alloying time of 2 h is more homogeneous, relatively sleek and compact without surface micropore and other common surface blemishes. The potentiostatic and potentiodynamic polarization measurements manifest that Nb-modified 430 SS prepared under the diffusion alloying time of 2 h enormously ameliorate the corrosion resistance of bare 430 SS compared with other Nb-modified 430 SS samples and its corrosion current density is maintained at −1.4 µA cm⁻² in simulated anodic environment of DFAFC (0.05 M H₂SO₄ + 2 ppm HF + 10 M formic acid at 50 °C).

The effect of diffusion alloying time on the corrosion resistance and surface conductivity of Nb-modified 430 SS has been carefully studied. The Nb-modified 430 SS samples prepared at the diffusion alloying time of 2 h have the best surface electrical conductivity and corrosion resistance in the simulated anodic environment of DFAFC.

The purpose of this study is to prepare core-shell ferrites/kaolin pigments and compare their efficiency in protecting metal substrates to original ferrites. The new pigments are based on precipitating a shell of different ferrites that comprise only 10-20 per cent of the whole pigment on kaolin (core), which is a cheap and abundant ore comprising 80-90 per cent of the prepared pigment. These new pigments combine the properties of both its core and shell counter-parts, exhibiting improved corrosion protection properties. Furthermore, the pigments are represented as efficient, economically feasible and eco-friendly with comparable efficiency to that of original ferrites in protecting steel substrates.

The new pigments were characterized using different analytical and spectrophotometric techniques, e.g. transmission electron microscopy, energy-dispersive X-ray analysis and X-ray fluorescence. The pigments were then incorporated in epoxy-based paint formulations. The physico-mechanical properties of dry films and their corrosion properties were tested using accelerated laboratory tests in 3.5 per cent NaCl for 28 days.

The results of this study revealed that ferrite/kaolin core-shell pigments performance was almost close to that of the ferrite pigments in the protection of steel, and, at the same time, they confirmed good physico-mechanical properties.

These pigments can be applied in other polymer composites, e.g. rubber and plastics, as fillers and reinforcing agents.

Ferrite and ferrite/kaolin are environmentally friendly pigments, and they can impart high anticorrosive behavior to paint films with concomitant cost savings.