Comparative effects of cement,coal dust and fly‐ash on H. Abelmoschus

Three types of dusts, i.e. cement, coal and fly‐ash were applied daily at the rate of two grams per square metre per day to 15 days old plants for a period of one month. Visible foliar symptom, photosynthetic pigment content and dry weight were taken as parameters. Small chlorotic spots and marginal chlorosis appeared in leaves sprayed with cement and coal dust respectively. Cement dust was more toxic to chlorophylls than coal dust, while a slight increase was noted in case of fly‐ash. Carotenoids were relatively unaffected by dust pollution.     

By‐products formation in catalytic combustion of aromatic compounds over a pt‐based catalyst

By‐products formation in the catalytic combustion of different aromatic compounds has been experimentally investigated. A commercial Pt‐based catalyst, in the shape of a short monolith, has been employed. Toluene, styrene, o‐xylene and cumene have been tested at low concentrations for conversions in the range 5–50%. The results confirm the formation of benzene in the combustion of toluene and styrene, as previously observed by other researchers, but in a very small amount; testing cumene, significant amounts of acetone have been found in the outlet flow. Some hypothesis about the reaction mechanism are put forward.     

Forest exploitation in Cameroon (1884–1994): an oxymoron of top‐down and bottom‐up forest management policy approaches

Forest exploitation in Cameroon goes back to the pre‐colonial period when early ethnic settlers used the ‘law of status’ system to manage land and forests in the territory. With the arrival of colonial powers, beginning with the Germans in 1884, the law of status system was replaced by top‐down state‐centred management system. This top‐down management system was inherited by post‐colonial authorities and enforced until 1994 when a new forestry law was launched, based on bottom‐up management system. This paper reviews all these three systems. Communities are not benefiting from an actual bottom‐up management system. The author argues that the forests sector in Cameroon needs a new management paradigm.     

Geo‐environmental characteristics of modified and ordinary bentonitic soils exposed to MTBE

Methyl tertiary‐butyl ether (MTBE) is the most common oxygenated fuel additive used to increase the octane rating and enhance the combustion efficiency of gasoline. This product is characterized as a harmful compound by the US EPA and has been shown to be a health threatening contaminant for human beings. The most contingent route for MTBE to enter the environment is its leaking from underground storage tanks (USTs). To avoid soil and groundwater contaminations because of leaking of MTBE, we investigated the performance of both modified and ordinary bentonite clays as liner systems at USTs sites in this study. Modified bentonites are synthesized by changing the original metallic cations in the structure of bentonite particles, thus converting the bentonite from hydrophilic to organophilic nature. In this research both modified and ordinary bentonites were investigated to evaluate MTBE adsorption efficiencies. As permeability is a major parameter in measuring contaminants flow in soils, tests were conducted to measure the permeability characteristic of bentonites. X‐ray diffraction (XRD) analyses were also carried out to evaluate the adsorption of MTBE to bentonites. The results indicated that basal spacing of modified bentonite particles was increased from 28.64 to 42.32 Å, thus showing MTBE adsorption to the soil. In terms of permeability tests, modified bentonites showed much lower permeability values compared to ordinary bentonites (1.9 order of magnitude reduction) when exposed to MTBE. Modified clays are a viable option for use as liner system material at MTBE contaminated sites.     

Effect of ethanol on the performance,emission and combustion characteristics of a compression ignition engine fuelled with vegetable oil–diesel blend

Experimental work had been carried out to analyse the effect of ethanol on the performance, emission and combustion characteristic of vegetable oil–diesel blend (50% vol. rapeseed oil and 50% vol. diesel fuel). The vegetable oil–diesel–ethanol blended fuels were prepared by using microemulsification technique and the main properties were measured. The results showed that, with the increase in ethanol volume fraction in the blends, the viscosity and density were decreased and close to those of diesel fuel. The combustion started later; the peak cylinder pressure, peak heat release rate varied significantly under different operating conditions and the corresponding crank angles of the peak values were retarded. There were slightly higher brake-specific fuel consumptions. Smoke and nitrogen oxide emissions were observed to reduce, but carbon monoxide and hydrocarbon emissions were found slightly higher with the increase of ethanol volume fraction under all ranges of engine operating conditions.     

Estimating Undrained Shear Strength of Soft Clay Ground Improved by Pre-Loading with PVD — Case History in Bangkok—

The installment of pre-fabricated vertical drain (PVD) combined with pre-loading is an efficient way to gain the prescribed strength and compressibility of very soft clay over a short period of time. This note describes case histories of such improvement performed in Bangkok. The change in undrained shear strength, s_u, before and after the ground improvement was investigated at two sites in Bangkok area by means of field vane test (FVT) and flat dilatometer test (DMT). The results of FVT showed that the s_u value of soft Bangkok clay increased over nearly the full depth down to the tip of the PVDs. It is also demonstrated that DMT may be a useful tool for promptly assessing the change of s_u in soft clay due to pre-loading. Applicability of the SHANSEP method in estimating the profile of s_u with depth in recently overconsolidated clay ground after pre-loading is also discussed.     

Women's self‐perception: an inter‐sector comparison of construction,legal and nursing professionals

The issue of gender in the construction industry has received considerable attention. However, most of the research has been from a male perspective and has considered how male perceptions of females act as an impediment to women's career progression. An understanding of women's self‐perception is important because it helps to explain how women make sense of the barriers and challenges they face in a male dominated culture and how they seek to attain positive outcomes for themselves. A comparison of women in the construction industry with women in other male‐dominated (legal) and female‐dominated (nursing) industries reveals little variation in self perceptions. Indeed, women in the construction industry emerge relatively positively, with the highest overall level of self‐esteem. This is encouraging and surprising, given the considerable evidence of significant barriers to entry and career progression for women in the construction industry, compared to other industries. It indicates that the construction industry is not a special case and that support strategies used in other industries are directly transferable, although the culture of the construction industry may make them more difficult to implement.     

Australian project time‐cost analysis: Statistical analysis of intertemporal trends

In statistical analysis of intertemporal movements in time–cost relationships via the Bromilow model it is shown that for Ng et al.’s (2001) Australian data, the K value is not significantly different from unity. This is utilized to develop a new and simpler ratio measure of the time–cost relationship, which has the advantage of being obtainable for each project. A scatter plot and a statistical analysis of the project ratios indicate significant yearly fluctuations but no underlying trend. Assuming similar characteristics of the data from previous studies, equivalent average ratios are estimated and plotted, confirming Ng et al.’s visual appearance of a possible downward trend. However, the statistical analysis is inconclusive on the issue, there being insufficient data (six points) for a full analysis.     

May land use change reduce the water deficiency problem caused by reduced brown coal mining in the state of Brandenburg?

Surface mining alters the water regime not only locally, but also regionally. The reduced brown coal mining in the south-east of the state Brandenburg (Germany) leads to decreasing river discharge and consequently to a shortage in the water supply. Land use change is one possible option to counteract this development. In this simulation study, we explored the impact of temporary and permanent set-aside of arable land on Brandenburg’s regional water balance. Temporary and permanent set-aside were considered as major measures towards deintensification of agriculture. Simulations were performed using the regional ecohydrological model SWIM, which integrates hydrological processes, vegetation growth, erosion and nutrient dynamics. The model was used to simulate the consequences of different land use change scenarios on main components of the regional water balance. Changes in the use of arable land altered clearly its water balance. The impact of these changes on the regional water balance for Brandenburg did not exceed ±10% for its single components. Opposite tendencies were established in the simulations by contrasting effects of temporary and permanent set-aside of arable cropland. While temporary set-aside increased runoff from the whole area up to 6.7% due to lower evapotranspiration and higher soil moisture in arable land, the conversion of agricultural land within river corridors to meadows had an opposite effect on regional runoff (6.9% decrease) due to higher water retention coefficients and higher evapotranspiration losses. Therefore, only temporary set-aside may compensate to some extent for the anticipated decrease in river discharge.     

Fractionation of total water soluble aluminium in extracts from peat and sand soil samples by ion‐exchange method followed by GF AAS

This study attempted the use ion‐exchange resins in order to fractionate total water soluble aluminium in extracts collected over acidic peat and alkaline sand soils. Extraction was performed in neutral and acidic conditions in order to imitate the behaviour of natural or acid rains. The total aluminium content in soil extracts and fractions was determined by graphite furnace atomic absorption spectrometry (GF AAS). In order to retain aqua Al³⁺ and hydroxycomplexes of aluminium Chelex 100 was used. It was found that fractionation of the aluminium in extracts depends strictly on the type of soil. When neutral spring water was used for the extraction the content of water soluble aluminium was found to be over two times higher in case of peat soil when compared with sand soil extract. Acidification of water by addition of HNO₃ and H₂SO₄ (2:1) pronounced in much extend the extraction efficiency of aluminium only form sand soils (over 10 times) but did not change proportion in fractionation of the particular aluminium species. Admittedly in the case of peat soils no significant increase in total aluminium content was observed but the concentration of cationic forms in acidic extract increased twofold when compared with the neutral extract.     

Safety climate in conditions of construction subcontracting: a multi‐level analysis

A multi‐level safety climate model was tested in the Australian construction industry. Subcontracted workers’ perceptions of the organizational safety response (OSR) and supervisor safety response (SSR) in their own organization and that of the principal contractor were measured using a safety climate survey administered at a large hospital construction project in Melbourne. One hundred and fourteen construction workers completed the survey, representing nine subcontractors engaged at the project. Two requisite conditions for the existence of group‐level safety climates, i.e. (1) within‐group homogeneity; and (2) between‐group variation were satisfied for perceptions of subcontractors’ OSR and SSR. This supports the contention that subcontractors working in a single construction project exhibit a unique group‐level safety climate. Subcontracted workers also discriminated between group‐level safety climates (i.e. the SSR) in their own and in the principal contractor’s organizations. The results suggest some cross‐level influence. Perceptions of the SSR were positively predicted by perceptions of the OSR in both the principal and subcontractor organizations. Perceptions of the OSR of the principal contractor were also a significant predictor of the perceived OSR and SSR in the subcontractor organizations. Perceptions of the subcontractors’ SSR were a significant predictor of the rate of lost‐time and medical treatment incidents reported by the subcontractor. Although perceptions of the principal contractor’s SSR were not directly related to subcontractors’ injury rates, they were a significant predictor of subcontractors’ SSR, revealing an indirect link. The results suggest that supervisory personnel (e.g. foremen and leading hands) play an important role in shaping safety performance in subcontracted workgroups.     

Trading properties after the earthquake: the rebuilding of eighteenth‐century Lisbon

This paper introduces the innovative system used in the reconstruction of Lisbon after the 1755 earthquake. Its findings are based on original documents that offer a detailed picture of the principles and methods established to convert the land and properties of the old city into the new and standardized gridded Plan. Implemented in the mid‐eighteenth century, the methodical system outlined was, undoubtedly, an important point of reference for the large‐scale urban improvement and redevelopment operations that would follow in nineteenth‐century Europe.     

Self-ignition of natural fuels: Can wildfires of carbon-rich soil start by self-heating?

Carbon-rich soils, like histosols or gelisols, cover more than 3% of the Earth's land surface, and store roughly three times more carbon than the Earth's forests. Carbon-rich soils are reactive porous materials, prone to smouldering combustion if the inert and moisture contents are low enough. An example of soil combustion happens in peatlands, where smouldering wildfires are common in both boreal and tropical regions. This work focuses on understanding soil ignition by self-heating, which is due to spontaneous exothermic reactions in the presence of oxygen under certain thermal conditions. We investigate the effect of soil inorganic content by creating under controlled conditions soil samples with inorganic content (IC) ranging from 3% to 86% of dry weight: we use sand as a surrogate of inorganic matter and peat as a surrogate of organic matter. This range is very wide and covers all IC values of known carbon-rich soils on Earth. The experimental results show that self-heating ignition in different soil types is possible, even with the 86% inorganic content, but the tendency to ignite decreases quickly with increasing IC. We report a clear increase in ambient temperature required for ignition as the IC increases. Combining results from 39 thermostatically-controlled oven experiments, totalling 401 h of heating time, with the Frank-Kamenetskii theory of ignition, the lumped chemical kinetic and thermal parameters are determined. We then use these parameters to upscale the laboratory experiments to soil layers of different thicknesses for a range of ambient temperatures ranging from 0 °C to 40 °C. The analysis predicts the critical soil layer thicknesses in nature for self-ignition at various possible environmental temperatures. For example, at 40 °C a soil layer of 3% inorganic content can be ignited through self-heating if it is thicker than 8.8 m, but at 86% IC the layer has to be 1.8 km thick, which is impossible to find in nature. We estimate that the critical IC for a ambient temperature of 40 °C and soil thickness of 50 m is 68%. Because those are extreme values of temperature and thickness, no self-heating ignition of soil can be expected above the 68% threshold of inorganic content. This is the first in-depth experimental quantification of soil self-heating and shows that indeed it is possible that wildfires are initiated by self-heating in some soil types and conditions.     

Photodegradation of selected β-blockers in aqueous fulvic acid solutions: kinetics, mechanism, and product analysis

The photodegradation of the widely used β-blockers atenolol and metoprolol were investigated in the presence of fulvic acid (FA) under simulated sunlight. Both atenolol and metoprolol undergo indirect photodegradation in the FA solutions. The triplet excited state of FA (³FA^∗) was verified to be main reactive species responsible for the photosensitized degradation of β-blockers. An electron transfer mechanism for the interaction between β-blockers and ³FA^∗ was proposed on the basis of a series of experiments. Magnetic property of metal ions exhibited significant impact on photosensitized degradation. Diamagnetic metal ions such as Mg²⁺, Ca²⁺, Zn²⁺, and Al³⁺ negligibly affected the degradation. In contrast, paramagnetic metal ions including Mn²⁺, Cu²⁺, Fe³⁺, and Cr³⁺ markedly inhibited the reactions in the order of Cr³⁺ < Fe³⁺ < Cu²⁺ < Mn²⁺. The inhibition was related to the complexation ability with FA. By LC-ESI-MS/MS analysis, deisopropyl-atenolol (metoprolol) was identified as the main photosensitized product. The degradation pathways of β-blockers involving electron transfer processes were proposed. This finding strongly suggests that ³FA^∗ was important reactive species for the degradation of β-blockers in natural waters.     

Tempo-spatial characteristics and influential factors of rockburst:a case study of transportation and drainage tunnels in Jinping Ⅱ hydropower station

Jinping Ⅱ hydropower station is located in a high in-situ stress region in Southwest China. During the excavations of the transportation and drainage tunnels, more than 460 rockburst events were recorded in the transportation tunnel and 110 in the drainage tunnel, which has a serious and negative influence on the tunnels' construction and the safety of staff and equipment. In the paper, the characters of rockburst patterns are analyzed for the transportation and drainage tunnels. The results are illustrated...     

An analysis of sustainable development and environmental protection in postcommunist countries: the case of croatia‐a view point

The paper analyses the origins, the definitions, and the implementation of sustainable development in the post‐communist countries of Central and Eastern Europe, using Croatia as an example. The overview of events in environmental concern world‐wide, in the last 25 years, shows that there is evidence of fast changes which have left the former communist countries behind. The major concern of the paper is the lack of an agreed upon definition and criteria on what sustainable development actually represents, and why it is still an odd subject in the Central and Eastern European region. Five recognition criteria described in the open literature are compared with the situation in the region. Using the examples of implementation of new UN Conventions, accepted at the UNCED Conference in Rio de Janeiro in 1992, the paper discusses the shortcomings and obstacles to current policies of sustainability.     

Input structure of the construction industry: a cross‐country analysis, 1968–90

During the past several decades, globalization has led to the integration of product markets. Rapid increases in cross‐border economic, social, technological and cultural exchange have become the key elements of knowledge diffusion and thus technology spillovers among countries. As a result, the debate as to whether absolute convergence occurs at the cross‐country level has increasingly attracted the attention of researchers. The aim of this study is to examine the changes in the input structure of the construction industry in nine developed countries between the late 1960s and 1990 and to evaluate whether convergence occurs at input industry level. The analysis of the technical coefficients for 35 industries reveals that, across countries and over time, not only the key inputs but also the new high and low input industries are similar. The estimation of variance factors on the other hand suggests that (1) during the sample period, the input structure of the industry is dominated by divergence rather than convergence; (2) among the input industries, services in particular tend for convergence; and (3) manufacturing inputs provide a mixed picture where only a few inputs show convergence and the remaining inputs show in general weak divergence.     

Effect of temperature on the soil–water retention characteristics in unsaturated soils: Analytical and experimental approaches

In unsaturated soil mechanics, the soil–water retention curve (SWRC) continues to play an important role, since it provides the necessary links between the properties and behaviour of unsaturated soils with a variety of engineering challenges. The temperature has been identified as the main factor influencing SWRC as compared to a variety of other parameters. The goal of this research is to describe theoretical and experimental aspects of the temperature effect on unsaturated soil water retention phenomena. Theoretically, a brief review of the constitutive laws governing the thermal-hydro-mechanical (THM) behaviour of unsaturated soils is presented, along with links between variations in suction with water content, temperature, and void ratio. It also provides a broad framework that would to be well adapted to describing many specific circumstances. Through a closed-form predictive relationship that is developed in this framework, the effect of temperature is examined. By using this relationship, the soil–water retention curve at arbitrary temperature could be determined from one at a reference temperature, therefore significantly decreasing the number of tests necessary to describe the thermo-hydro-mechanical behaviour of a soil. Besides, the SWRC of kaolinite clay was also measured at three different temperatures in an experimental program. The test findings reveal that when the temperature rises, the SWRC decreases significantly. The experimental results were then integrated with sixteen other available data sets covering a wide range of soil types, densities, and suction to create a complete verification program for analytical models. The proposed model has a good performance and reliability in forecasting the fluctuation of non-isothermal SWRC than any existing model, according to statistical assessment results. The analytical model can be used to examine the thermo-hydro-mechanical characteristics of unsaturated soils in numerical simulations.     

Peri‐urban informal housing development in Victorian England: the contribution of freehold land societies

Self‐help housing in peri‐urban areas (usually outside municipal boundaries) is a feature, not only of rapidly urbanizing countries now in the South, but was also in Victorian England, where it was often initiated by freehold land societies, created by the Chartist movement in order to expand the franchise. These bodies bought and subdivided land for sale to their members, and laid out roads, using legal powers conferred upon the building societies. The societies made a significant contribution to housing for the urban working class, and preceded the garden city and town planning movement promoted by Liberal politicians. A case study is presented of one successful provincial society, the Ipswich and Suffolk Freehold Land Society.     

America's high‐level nuclear waste repository: a case study of environmental science and public policy

The disposal of high‐level commercial nuclear wastes, the so‐called spent fuel, is one of the most politically and ethically complex environmental issues. A series of actions taken over past decades has resulted in plans to dispose of spent fuels in geologic repositories. This decision has ignited numerous controversies, especially concerning where the repositories should be located. This siting controversy has been “settled” for the time being by a federal law that designates Yucca Mountain in southern Nevada as the preferred location. However, the decision: (a) is inconsistent with the National Environmental Act as a comprehensive policy act, (b) does not reflect full consideration of value‐laden public policy issues, and (c) adds to credibility problems confronting the US Department of Energy and therefore contributes to controversies surrounding the agency's decisions. Aspects of how this decision came about and how it is being implemented provide an interesting case study of how our society is presently dealing with scientifically, politically, and ethically complex technological problems.