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The purpose of this study is to attempt to compare experimental results for a number of models for the prediction of the drying time of new concrete floors. The investigated methods are the table method, the Swedish Concrete Association (SCA) method and the free computer programme TorkaS 3.2.

The comparison is based on moisture measurements of four different floor specimens. The specimens have different ratios (w/c = 0.38, 0.6 and 0.7).

The results show that there is a good agreement between the table method and the measured values on the specimens with high water-cement ratio (w/c = 0.6 and 0.7). However, the deviation becomes greater at lower water-cement ratio (w/c 0.38). TorkaS also resulted in a good agreement with the measurements. However, it is noted that as the drying time increases, the programme exhibits a slow dehydration trend at higher w/c ratios. The SCA method shows various results within the permissible deviation. Moreover, the moisture distribution in concrete with high w/c ratios is found to be mainly influenced by moisture diffusion and little by self-desiccation.

This study is limited to concrete slabs that are drying from one side in an enclosed building with an heating, ventilation and air conditioning (HVAC) system operating normally. Moreover, this study concerns concrete without special additives (e.g. silica fumes), which can be used in some specific cases to accelerate or retard the hydration (cure) process.

These compared methods are used widely in Sweden; therefore, it will be interesting to understand their applicability range. Another focus in this paper is to investigate how the effect of self-desiccation of concrete is related to the w/c ratios, taking into consideration the result of these prediction models.

The paper can suit academic researchers, as well as the commercial industries, in a sense that the comparative study will pave a way to the best method to be used for drying time estimation.

The paper contains new information and could be useful to researchers and commercial industries.

This chapter presents a case study on smallholder vulnerability and adaptation to long-term desiccation in the West African Sahel. Climatologists recognize Sahelian desiccation as a long-term multi-decadal dry period that persisted from roughly 1968 to 1995. This study draws on fine-scale ethnographic and daily rainfall data to elucidate local perspectives on this broad regional process. As such, this provides a window on the local lived experience of regional climate variability.

This study draws on multiple periods of ethnographic fieldwork in two different Mossi areas in north-central Burkina Faso (West Africa). Fieldwork consisted of key informant interviews, household surveys, and participant observation. The authors incorporate daily precipitation data from two meteorological stations provided by the General Directorate of Meteorology of Burkina Faso. Researchers assembled this data and graphed daily rainfall totals for individual rainfall seasons in the years preceding each period of fieldwork. The qualitative and quantitative data are analyzed by using a Sustainable Livelihoods (SL) framework.

The study finds that local perceptions of increased rainfall variability correspond to patterns evident in daily rainfall records for individual stations. Additionally, the authors document how rural producers are negatively affected by both intra-seasonal and multi-decadal rainfall variability. Mossi smallholders have adapted through new cropping patterns, livelihood diversification, and investments in agricultural intensification. These adaptations have been largely successful and could be adopted by other Sahelian groups in their efforts to adapt to climate change.

Fieldwork took place over several years in two different departments and five localities. The two anthropologists used a common livelihoods analytical framework but different research protocols over this time span. Thus, the data collection was not systematic across all locations and time periods. This limits the degree to which results are representative beyond surveyed localities at their respective points in time.

This study presents local views and perceptions of regional climate variability and ecological change. It is a rare bottom-up perspective supplemented with precipitation data.

The purpose of this paper is to evaluate the influence of a mixture of nutrient solution, bacteria and biofilm on the consolidation, unconfined compression and desiccation characteristics of two soils that could be used in waste containment applications.

Experimental work was conducted to investigate the influence of biofilm on the desiccation, strength and consolidation characteristics of two barrier soils. The soils were evaluated with water alone and with a biofilm solution composed of nutrients, bacteria and exopolymeric substances (EPS). These solutions were mixed with a locally available clay (“red bull tallow” (RBT)) as well as a mix of 65 percent sand and 35 percent bentonite (65‐35 Mix).

Reductions in strength and increases in ductility are observed with biofilm amendment for two soil types. The shear strength was reduced from 413 to 313 kPa and from 198 to 179 kPa for RBT and 65‐35 Mix, respectively. Desiccation tests reveal an increase in moisture retention for early time increments in amended specimens, while both increases and decreases are noted after extended drying. Increases in the rate of consolidation and modest decreases in the compression and swell index were observed. In particular, the consolidation coefficient was increased from 0.036 to 0.064 cm²/min and from 0.060 to 0.093 cm²/min for RBT and 65‐35 Mix, respectively.

These results are useful in establishing the broader impacts of using biofilm as an additive to increase the performance (e.g. reduce hydraulic conductivity and increase resistance to crack formation) of barrier materials in waste containment applications. Moreover, the data provide insight into the geotechnical implications of biofilm‐producing methanotrophic activity that occurs naturally in the covers of municipal solid waste landfills.

Very little research has been published on the influence of biofilm on the behavior of barrier materials in general, and on geotechnical properties in particular. This paper is unique in making the connection between methanotrophic activity, soil modification and barrier material performance.

In this chapter, the title theme of “Disaster by Design” is explored and justified. Even from early times, the Aral Region was subject to alterations of natural conditions due to human intervention, often deliberate and designed. After the final conquest by Russia, the region became a fixed colony as part of the Soviet Union, ripe for exploitation characteristic of the Soviet approach to nature broadly and to stigmatized areas specifically. The Aral region was selected for irrigated cotton and other cultivation even though the consequences for desiccation of the sea, desertification, and salinization were understood. The decision was so calculated that even a cost–benefit analysis was offered to show that the Aral fishery was worth but a fraction of the cotton potential. The destruction of the region was made possible by a Soviet system of central planning and peripheral control. The brief glimmer of hope for the region evidenced during glasnost was the only moment where the Aral's fate was not sealed. The outcome is a model of ecological disaster by design, an environmental injustice, and an indication of the abusive nature of authoritarian power.

Heat treatment, in view of later knowledge, is seen to have other effects than to destroy or lower the vitality of micro‐organisms initially present; there are the more obvious changes of flavour and of consistency brought about by the partial cooking, but there are also the possible lowering of the vitamin potency and the still more subtle changes in the salts which may, after heat treatment, be rendered less available than in the raw product. The importance of these considerations cannot be too much stressed when it is remembered that heat treatment is, generally speaking, an inherent stage in the process of canning. It is the heat treatment which preserves the goods, the sealing of the can being merely a means of prevent re‐contamination. The chemist, no less than the physiologist, has been much concerned with the changes in foods caused by heat treatment as a method of preservation, and, as a result of his investigation, there is now a better understanding of the changes which take place, with a consequent improvement in the methods of processing. For a number of years, however, this country, in common with many others, has relied, in so far as its supplies of meat are concerned, on products preserved by “cold,” and the freezing of beef, the chilling of mutton, have made available to us the cattle of the Argentine and the sheep of New Zealand. Initially the processes employed were crude, the post‐mortem changes were imperfectly understood, conditions of storage, before, during and after shipment, were haphazard, and the methods of defrosting far from scientific. How far the methods have advanced, and to what extent the scientist has been concerned in the elucidation of the many problems, will be realised from the reports of the Food Investigation Board. It is not suggested that all the advance is due to the work of the Low Temperature Station a Cambridge—much has been done in other countries‐but the investigations carried out by the scientists a this station have been fundamental. Food producers in America were the first to realise the importance of the latest development in freezing, the advent of the “ Quick Freezing Processes ” marking a distinct advance in technique. When cellular tissue is normally frozen and subsequently defrosted, rupture of the cells may have occurred and the structure of the substance consequently partially broken down. When, however, the tissue is quickly brought down to a very low temperature, it is found that in many cases this breakdown in tissue does not take place. These principles have been applied to commercial installations, and fish, meat, fruit and vegetables so treated show on defrosting remarkably little change in character. Preservation by desiccation is a method employed for certain materials with great success. Sun‐drying of fruits (sultanas and dates, to quote but two) and the sun‐drying of cereal products such as macaroni is still practised. An important industry concerned with the drying of milk has developed in most milk‐producing countries, whilst dried eggs and dried egg‐albumin form important items of commerce. It is obvious that the object of concentrating such substances as fruit juices, milk and vegetables and animal liquid extracts is ideally to reduce the water content and obtain a product which, when the water is ultimately restored, gives a solution or material having the original taste, aroma and food value. The effect of heat is often, however, to change these characteristics, and although by the use of a vacuum the temperature to which the substance is submitted is lowered, changes still take place, and much of the aroma depending on volatile constituents is lost. To a very great extent this has been overcome by a method of desiccation which is essentially partial freezing, a method which has not yet received much publicity as it has only lately emerged from the experimental stage. The practical application of this principle is due to Dr. G. A. Krause, of Munich, who has invented and designed a dual process of concentration. In this process the liquid is first concentrated by freezing out water as ice, which is removed by mechanical separation in a centrifuge. By ingenious mechanical and regenerative devices this process has been made extremely efficient, the losses being only 1–2 per cent. of the original juice, although the efficiency is not maintained when the solids‐content of the product has been raised to 40–50 per cent. This liquid is then further concentrated by evaporation at a low temperature, about 10°–15° C. The differential evaporation of water as compared with the aromatic flavour constituents occurs because the removal of water as vapour at this temperature depends solely on the rate of diffusion of the molecules into the gas space. As water has a small molecule compared with the large molecules of the esters, ethers and alcohols of the flavouring substances, it escapes more readily ; the conditions of evaporation as given in the patent are all designed to aid this escape. A reduction in pressure may be used to speed up the process without interfering with the differential diffusion, and the provision of an atmosphere of small molecules (e.g., hydrogen) also has the same effect. A large surface for the evaporation is made by spreading the liquid as a thin continuously renewed film. The condenser is situated very near the evaporating liquid to remove the water molecules quickly (a distance of 3 cm. is the maximum diffusion path). The atmosphere may be circulated or disturbed to hasten the diffusion and, most ingenious of all, it may be blown towards the evaporating liquid when, if a velocity is used just greater than that of the heavy molecules leaving a liquid surface, the loss of flavour may be entirely eliminated while the rate of water evaporation is only reduced by 10 per cent. By these means a concentrate containing as much as 65 per cent. solids and capable of storage without deterioration at ordinary temperatures may be prepared, and 80 per cent. of the original vitamins retained. The use of refrigeration in the preservation of food has necessitated the use of refrigerated transport to complete the links between producer, manufacturer, retailer and customer. The variety of commodities and the different conditions they need create varying demands on the methods of insulating and refrigerating transport vehicles. The British railways have 4,000 refrigerated railway vans, and such vans, containing perishable produce, came regularly to England from Austria and Italy by way of the train ferries. These vans are designed for fairly high temperatures, 35–40° F., and long hauls, and use ice as a refrigerant. At the other end of the scale is the road vehicle, which may have a temperature as low as 0° F., but is only on its journey about 12 hours. It is in these road vehicles that the greatest advances have been made, for conditions in England do not justify the railways in expenditure on elaborate equipment. The early road vehicles were insulated boxes on a lorry chassis and were refrigerated by ice and salt, which was “messy” and caused bad corrosion of the chassis. The introduction of an eutectic solution, virtually a mixture of a freezing salt and water in a definite proportion, which was frozen as a whole in a sealed tank, was made some few years ago. This removed the “messiness,” conserved the salt and produced greater efficiency and a more stable temperature.

This chapter provides a brief overview of our understanding of major public health challenges and environmental concerns in Karakalpakstan today, and highlights questions that still remain unanswered. As seen in the case of Muynak, the fishing town on the southern edge of the former Aral Sea, ecological disasters do not happen alone – they spur socioeconomic disasters that only heighten the health disasters. The loss of the sea, the loss of local livelihoods, and mass out-migration of the population, along with economic depression following the collapse of the Soviet Union, have adversely affected the community living in Muynak. They face major public health challenges, such as tuberculosis, multidrug resistant tuberculosis, and anemia as a result of their impoverishment. The desiccation of the Aral Sea is but one of the many disasters linked to intensive cotton cultivation in Uzbekistan. Pesticide contamination and the salinization of drinking water in Karakalpakstan are yet other environmental disasters that further threaten the health of the population and of future generations. Currently, there is an urgent need for greater international involvement and collaboration with Uzbeks to reverse the poor public health trends and to study the extent of environmental contamination in communities across Karakalpakstan, in order to reduce the health threats presented by these.

Much of the housing stock in the UK is built on shrinkable clay soils, particularly in the south‐east of the country. When the moisture content of the clay soils is reduced the clay shrinks causing downward movement. This extraction of moisture from the clay may occur in a number of ways, but the main causes are either prolonged periods of dry weather (a combination of high average temperatures and low average rainfall) or tree roots extracting the moisture from the soil in close proximity to a property. The most extreme cases occur when a combination of the two causes is evident. Over the past few years the UK has seen some of the driest periods of weather on record which has meant that clay soils have not been able to replenish their seasonal moisture loss during the winter months. This has caused an increase in the number of cracks appearing in properties and a rise in the number of subsidence claims made against insurance companies. If climatologists are right about global warming, then subsidence damage has become an endemic hazard of home ownership. Prolonged periods of dry weather will continue to cause serious and very expensive damage to the country’s housing stock. The annual subsidence bill of £300 million can only be reduced by improving education and communication within the construction industry and encouraging house owners to look after their investments more carefully. This paper attempts to identify how the cost of subsidence damage can be reduced despite the changes in climate conditions.

The investigation of root‐induced clay shrinkage cases can be difficult. The soil suction technique is an invaluable aid to correct diagnosis, quickly and cheaply. Incorrect diagnosis can be costly. This paper explains how new methods of soil testing can help.

Introduction As long ago as 18411 it was known that trees can cause movements of adjacent ground if the soil contains appreciable quantities of clay. However, it is in comparatively recent times that researchers in the UK have attempted to understand how the process of tree‐induced ground volume change comes about. In the first instance, studies were inspired at the Building Research Station, immediately following the Second World War, by investigations of claims for compensation for bomb damage that revealed the close proximity of trees to buildings that were remote from locations where bombs had fallen. These studies concentrated on establishing the ability of vegetation to dry the ground, and on determining the depth at which building foundations should be placed to prevent damaging movements occurring through the action of light vegetation. This early work also pointed out the risks of subsidence from tree root activity and the need for deeper, piled foundations when building close to trees. Though several BRS publications were issued, the problem was not widely appreciated.

Numerous problems have arisen in the application of freezing methods to the various types of food products. One problem is concerned with the determination of the direct effects of low temperatures upon the food itself and another problem is to determine the effects of low temperatures upon other factors which may in turn affect the quality of the food. We are especially interested in knowing the exact effects of freezing and other low temperatures upon the micro‐organisms associated with foods. Bacteria constitute the most significant group of micro‐organisms affecting the sanitation and keeping qualities of foods. Those bringing about the decomposition of food products, while they are many and vary greatly, depending upon the nature of the food, are chiefly organisms from the air, water and soil. The types of bacteria found in foods vary greatly in their action on the food and also in reaction or response to varying temperature conditions. The action of micro‐organisms on foods of high carbohydrate content results in fermentations, while the action of the micro‐organisms on foods of high protein content will result, chiefly, in putrefactive changes. The former type of change usually occurs at a more rapid rate, when conditions are favourable, but the latter change usually results in a more undesirable condition of the food. While certain types of bacteria grow best at temperatures well above human body temperatures and others even as low as the freezing point of water, a large majority of those found in foods and the ones normally responsible for the detrimental changes in foods, are active only between 50° and 100° F. It is this latter group which is most implicated in food spoilage and it is significant that this group will be most effectively suppressed by low temperatures. Bacteria are much less affected by low than by high temperatures. Cold alone does not kill most types of bacteria, but slows down their activities to such an extent that they multiply very slowly, if at all. Many bacteria will die off, however, when held at a temperature below that which permits growth and reproduction. Bacteria, generally speaking, will be more easily killed when frozen in pure water than when frozen in foods containing albuminous matter and fats. There are a few bacteria of the cold‐loving type, which may actually multiply and cause slow decomposition at temperatures of 0° C. or less, if substances in solution are present to depress the crystallising point of water. Cold not only retards the growth of bacteria by the direct physiological effect of slowing down the rate of metabolism, but also depresses bacterial activity through its effect on their water and food supplies. Bacteria cannot grow and multiply in a completely frozen or crystallised medium, since they are by nature aquatic and are unable to carry on their normal activities except in a liquid medium. There is no evidence that bacteria maintain a body temperature which would make water available from a completely frozen medium. Bacteria may only utilise food when it is in soluble form, and thus capable of diffusion through their semipermeable cell membranes. When the temperature is sufficiently low to cause the crystallisation of most of the water, the remaining constituents become relatively more concentrated and this will further suppress the activity of the bacterial cells by affecting their osmotic pressures. These effects are very similar to those of partial desiccation or drying. In the course of experimentation some very striking examples of bacterial resistance to low temperatures have been reported. Lactobacillus and aerobacter have been reported to survive in peas stored at −10° C. for two years; whilst bacteria of the genus Pseudomonas were reported to increase in numbers when stored at −4° C. In general it may be said that practically all pathogenic bacteria likely to be found in foods will die off rather rapidly at low temperatures. However, this should not be interpreted to mean that infected foods can be made safe by low temperatures alone. Among the disease producing bacteria transmitted through foods, those of special significance include the organisms and toxins of botulism, typhoid fever, the several organisms of food poisoning called ptomaine poisoning, belonging to the Salmonella group (Salmonella enteritidis, etc.), and various organisms causing infections of the general nature of dysenteries or summer complaints of infants and adults. Frozen foods present no greater threat of botulism than foods preserved by other methods, yet it has been shown that Clostridium botulinum spores may survive freezing at −16° C. for as long as 14 months. The vegetables when thawed become toxic in from three to six days. Experiments have shown that Clostridium botulinum in foods preserved by “quick freezing” and subsequent storage at temperatures below 10° C., show no toxin production for at least 30 days. The lower the temperature of storage the greater the protection against botulism. All foods in which Clostridium botulinum might be present, and which have not been thoroughly heated, should be refrigerated at or near the freezing point. All foods which may harbour the botulism organisms or toxins should be selected with special care, before they are frozen, and care should be taken to see that they are kept frozen until used by the customer. Frozen vegetables should be used immediately after thawing. Thawing and refreezing is always objectionable since such a practice leads to loss of quality, and since bacterial growth and activity may occur during the period of thawing. While the typhoid organisms (Eberthella typhosa) shows considerable variation in resistance to low temperatures, it has been shown that about 99 per cent. will be killed immediately by freezing. Temperatures below freezing apparently have little more effect than the freezing point temperature. Small numbers of the Salmonella and similar organisms of the food poisoning groups may survive in frozen foods for periods of several weeks. It has been shown, however, that no significant growth of activity of these organisms will occur if the foods are refrigerated at 5° C. (41° F.) or less. Moulds and yeasts are of relatively little importance in frozen foods, both from the standpoint of sanitation and food spoilage. While low temperatures will materially retard the rate of enzymatic changes within food products, there is evidence that such changes continue to take place in frozen foods, even considerably below the freezing point. These changes probably account, in part, for the fact that frozen foods once thawed, will decompose more rapidly than foods which have not been frozen.