Dry Duration Research Articles

Rehydrated Air-Dried Pap Smears as an Alternative to Wet-Fixed Smears

To assess the effect of rehydration on air-dried Pap smears and to compare them with conventional, wet-fixed smears. Paired cervical smears were obtained from 419 women. One set was labelled "Routine" (fixed immediately in 95% ethanol) and the other, "Rehydrated" (air-dried, rehydrated and then fixed). The latter were further subdivided into groups A-F depending on the duration of air drying. The staining quality of the smears was assessed, after adequate blinding to remove bias, and graded. The chi 2 test was performed to compare parameters in the two sets of smears. Of the 397 pairs found to have adequate cellularity, 6% of the Routine group and 4% of the Rehydrated were "unsatisfactory due to poor fixation." Smears rehydrated within two hours of air drying as well as those refrigerated within two hours and rehydrated after 48 hours produced a staining quality as good as that of the conventional, wet-fixed smears. Rehydration caused lysis of red blood cells in the background. Rehydration of air-dried Pap smears within two hours of preparation produces staining quality equal or superior to that of conventional, wet fixed ones. It has the added advantage of being less cumbersome for the clinical personnel involved in smear making.

Influence of Drying Procedure on the Mesoporosity and Surface Fractal Dimensions of Silica Xerogels Prepared with Different Agitation Methods

Silica xerogels were prepared by thermal drying wet gels in an electric oven (70°C) after certain duration of ambient drying, and the relevant effect is investigated on the mesopore structures and surface fractal dimensions of the resultant xerogels. The silica gels were derived from a hydrochloric acid-catalyzed TEOS (tetraethylorthaosilicate) system, and both magnetic stirring and ultrasonic vibration were adopted during sol preparation. The percentage mesoporosity and surface fractal dimensions are evaluated using image analysis methods, based on FE-SEM (field emission gun-scanning electron microscopy) images. The results show that the mesoporosity of the resultant xerogels decreases with the duration of ambient drying for samples prepared using magnetic stirring and low-intensity ultrasonic vibration, while samples subjected to high-intensity ultrasound show a somewhat reverse trend. Samples prepared with magnetic stirring have almost constant surface fractal dimensions (nearly 3), irrespective of the ambient drying before thermal drying. The surface fractal dimensions of samples prepared using ultrasound increase with the duration of ambient drying.

Freeze‐drying using vacuum‐induced surface freezing

A method of freezing during freeze‐drying, which avoids undercooling of a solution and allows growth of large, dendritic ice crystals, was investigated. Aqueous solutions of mannitol, sucrose, or glycine were placed under a chamber vacuum of approximately 1 mbar at a shelf temperature of + 10°C. Under these conditions, the solutions exhibit surface freezing to form an ice layer of approximately 1–3 mm thickness. On releasing the vacuum and lowering the shelf temperature to below the freezing point of the ice in the solution, crystal growth occurs to yield large, chimney‐like ice crystals. The duration of primary drying of a frozen cake—as measured by using inverse comparative pressure measurement—was up to 20% shorter than when using a “moderate” freezing procedure (2 K shelf temperature per min). With mannitol, however, the residual moisture content of the final dried product was higher than with moderate freezing, and with sucrose and glycine there was no difference. These findings are related to the structures of the dried cakes formed during freezing, as examined by light microscopy and wide‐angle X‐ray diffraction. The introduction of an annealing step (4 h at a shelf temperature slightly above the onset melting point of the ice in the frozen cake) combined with the vacuum‐induced surface freezing procedure maintains the rapid primary drying and produces a low residual moisture (0.2%) for the freeze‐dried mannitol solution.

Dry season survival, diapause duration and timing of diapause termination in the millet stem borer, Coniesta ignefusalis (Hampson) (Lepidoptera: Pyralidae) in Northern Ghana

Studies were conducted between 1996 and 1997 in Northern Ghana on the dry season survival tactics of the millet stem borer Coniesta ignefusalis (Hampson). Results confirmed that the main survival tactic employed by the insect was larval diapause, which lasts from November to May the following year. In both years, diapause termination occurred in the field 4-6 weeks after the resumption of the rains, depending on the year and location. Larval mortality rate was high during diapause with peaks occurring towards the end of the dry season in May. During the 2 years, larval populations declined by at least 50% between the start of diapause and its termination. No parasitoids were encountered during the study period, suggesting that biocontrol agents are probably not very important in the population dynamics of the insect. The implications of these findings for management of the pest are discussed.

Calcining silica gels at different drying stages

Silica gels derived from an acid-catalyzed tetraethyl orthosilicate (TEOS) system were calcined after different duration of ambient drying, and their mesopore structure and surface fractal dimensions are investigated. The largest mesopore porosity is found in the sample with long period of ambient drying, while the sample calcined without drying exhibits the lowest surface fractal dimensions.

Diversity and structure of turtle assemblages: associations with wetland characters across a floodplain landscape

We studied 24 wetlands along a 296‐km portion of the lower Missouri River floodplain, USA during 1996–1998. Our goal was to examine relationships between wetland characters and freshwater turtle diversity. We collected data on a total of 2201 individual captures of six freshwater turtle species. Ten species variables (richness, evenness, proportion of lentic species combined, proportion of lotic species combined, and proportions of six individual species) described the turtle assemblage structure and were associated with six broad wetland categories (remnant oxbow, remnant slough, connected scour, isolated scour, temporary farmed, and temporary not farmed) as well as with six abiotic (water depth, distance from the river, duration dry, duration flooded, size, and turbidity) and two biotic (primary and secondary productivity) wetland characters. Repeated‐measures MANOVA and ANOVA revealed highest diversity in remnant sloughs and oxbows as well as in newly created scour wetlands and lowest diversity in temporary wetlands. Multiple regressions and correlations indicated that the single most important wetland characteristic for high turtle diversity was a low annual duration of drying. Oxbows supported the highest proportions of lentic turtles; while connected scours supported the highest proportions of lentic turtles. Lentic species proportions were highest in wetlands that were frequently flooded, relatively distant from the Missouri River, and insect rich, while lotic species proportions were highest in wetlands that were turbid, close to the river, and relatively insect poor. The cohabitation patterns of several turtle species suggest that direct or indirect interactions between species may affect assemblage structure. Based on our broad array of wetlands, we identified crucial wetland types and characteristics that were associated with maximum diversity for freshwater turtles. Empirical studies similar to ours across broad landscapes are needed for a variety of wetland floral and faunal groups before sound conservation and management recommendations can be formulated.

Specifics of drying of building ceramics made using lubricant-coolant waste

Based on a study of the main physicochemical processes in the clay — water — surfactant system, the paper shows the possibility of using coolant-lubricant liquids in the production of building ceramics without significant changes in the technological process. In this way the duration of drying is reduced, heat energy is saved, and the amount of waste is decreased.

Modeling Polydimethylsiloxane Degradation Based on Soil Water Content

Polydimethylsiloxane (PDMS) is a widely used silicone polymer that is introduced into wastewater treatment systems where it is removed with sludge. PDMS subsequently enters the terrestial environment as a result of sludge amendment to soil. Laboratory studies have shown that PDMS extensively breaks down into monomeric units when in contact with dry soils. The byproducts of hydrolysis eventually biodegrade or evaporate. The objective of this study was to develop a computer model that can predict the degree of PDMS breakdown based on level and duration of soil drying under different climatic conditions. The framework of the model was the SHAW (Simultaneous Heat and Water) model that predicts daily water content distribution in soil over the course of a year. The soil water contents predicted from the SHAW model were then linked to PDMS degradation rate data for various soils to predict soil and climate impacts on PDMS losses. Field testing of the model at Columbus, OH showed that the model was able to predict the general trends in PDMS degradation over 2 years. Predicted PDMS concentrations remaining in the 0−10 cm depth 2 years after sludge addition were 19.8 mg/kg of soil compared to the measured values of 23.0 mg/kg of soil. The sensitivity analysis of the model showed that >95% of PDMS degraded at the soil surface in Bayamon sandy clay loam (San Juan, PR), Miamian loam (Columbus, OH), and Wedowee sandy clay loam (Athens, GA) soils within 365 days after application. However in some years, >50% of applied PDMS was still remaining at 2.5-cm depth 365 days after its application. At any given day, there was less PDMS remaining in soil at San Juan, PR, and at Athens, GA, than at Columbus, OH. This is because of (1) higher rates of PDMS degradation in Bayamon and Wedowee soils than in Miamian soil and (2) better soil drying conditions in Puerto Rico and Georgia than in Ohio.

HOT AIR AND MICROWAVE DRYING OF ONIONS: A COMPARATIVE STUDY

ABSTRACT This comparative study of conventional (hot air) drying and microwave drying of the onion was carried out on a hot air pilot plant drier for conventional drying where all characteristics (temperature, humidity, and velocity) could be adjusted and controlled. A data logger connected to a computer captured all data. And for microwave drying, a drying tunnel Fitted with a forward/backward movement was used. Mass loss and product surface temperature were monitored for both processing. Factors controlled where: frequency of movement, microwave power, air extraction rate. Other elements included shape (slices/pieces) and variety of product Drying duration and maximum drying rate constituted comparative criterion for the processes. Quality was measured by the reducing sugars and polyfructans content. Analysis of variance for the microwave drying process suggests that the effective factors were microwave power followed by onion variety and shape respectively. For quality criterion by far the most effective was variety, followed by the interaction of shape and the forward-backward movement of the conveyor. For conventional drying the most effective factor was air temperature for drying duration, and variety for maximum drying rate.

Wet and dry epoch durations of spatially averaged rain rate, their probability distributions and scaling properties

This article is concerned with the notion of duration of wet and dry epochs in stochastic processes of spatially averaged (instantaneous) rain rate over a given region. Gamma, Lognormal, and Inverse Gaussian parametric families of probability distributions have been considered as candidate models for the distribution of such durations. Goodness of these model's fit to data of dry and wet epoch durations obtained from real time series of spatially averaged rain rate, has been tested with Pearson's \(\chi ^2\)-test. The parameters of each of these models have been estimated by maximum likelihood and method of moments, based on TOGA-COARE measurements of tropical rainfall. The hypotheses of independence and identical distribution (i.i.d.) among durations of dry or wet epochs have also been tested using a certain version of the Wald-Wolfowitz test. Finally, the effect of spatial scale on the moments of dry and wet epoch durations has also been investigated, pointing to self-similarity of the underlying random structures over space. The main result of this study is that among the three candidate models, Inverse Gaussian is the one conforming most adequately with all the classical testing criteria implemented here, and also with the newly established scaling behavior of both dry and wet epoch duration processes over space. This is a remarkable finding, considering that the Inverse Gaussian family has recently been also justified from a theoretical viewpoint as a reasonable model for the probability distributions of dry and wet epoch durations.

The responses of Briza media and Koeleria macrantha to drought and re‐watering

1. To test whether differences in response to drought can help to explain the differing distributions of Briza media and Koeleria macrantha, changes in their leaf growth and water relations during soil drying were measured. After droughting, plants were re‐watered and recovery recorded. 2. Leaf growth of the two species showed a similar sensitivity to drought with respect to duration of soil drying and soil moisture content. 3. In both species tiller base relative water content (RWC) was maintained at similar levels to controls until soil moisture content had fallen to less than 9%. This may aid survival in habitats subject to periodic droughting by preventing damage to the meristems. 4. Briza media did not respond to re‐watering. However, plants of K. macrantha re‐grew after periods of over 20 days of drought, when tiller base RWCs had fallen as low as 13%. This ability to resurrect may explain the occurrence of K. macrantha in xeric calcicolous grasslands subject to episodes of severe droughting, from which B. media is absent.

Influence of pre‐storage drying conditions and duration of storage on the effectiveness of root inoculum of Glomus aggregation 1

A greenhouse experiment was undertaken to evaluate the influence of pre‐storage drying treatments and duration of storage on the effectiveness of root inoculum of Glomus aggregatum. Conditions under which roots were dried prior to storage had little or no effect on the level of arbuscular mycorrhizal (AM) effectiveness measured in terms of pinnule phosphorus (P) content of Leucaena leucocephala leaves after the first 14 days of storage. As duration of storage was further prolonged the time required by root inocula for initiating AM effectiveness and attaining peak levels of effectiveness was progressively prolonged relative to that required by the crude inoculum. However, the two sources of inoculum had similar peak AM effectiveness in many instances. Roots dried in the greenhouse or in the oven at 40°C were significantly inferior to that dried at 60°C. Root inocula stimulated growth of the indicator plant to the same extent as the crude inoculum after 14 days of storage. However, the effectiveness of root inocula in stimulating growth declined with further increase in duration of storage. Among root inocula tested, that dried at 60°C prior to storage was relatively more effective than that dried in the greenhouse or in the oven at 40°C. The overall inferiority of root inocula to that of the crude inoculum appears to be related to loss of viability of root inocula with increase in duration of storage.

EXPERIMENTAL ANALYSIS OF DESICCATION CRACK PROPAGATION IN CLAY LINERS1

ABSTRACT: A laboratory investigation on a scaled model of a landfill liner was conducted to provide data regarding the occurrence and extent of desiccation cracking of prototype liners. The crack intensity factor, CIF, was introduced as a descriptor of the extent of surficial cracking. CIF is defined as the ratio of the surface crack area A, to the total surface area of the clay liner, At. A computer aided image analysis program was used to determine CII’ values from scanned photographs of the desiccation process. The variation of the CII’ was related to duration of drying and measured soil moisture suctions.The soil of this investigation experienced significant cracking, with crack widths approaching 10 mm in the first drying cycle and penetration through the entire 16 cm thickness. Crack propagation was limited to a very intense period of the desiccation process. Nearly 90 percent of the crack development occurred during a 19‐hour time period, although the total duration of the desiccation cycle was approximately 170 hours. The soil moisture suction changed by only 2 bars during the period of rapid crack growth, although it changed by more than 40 bars during the period of reduced growth.

Freeze-Drying of tert-Butyl Alcohol/Water Cosolvent Systems: Effects of Formulation and Process Variables on Residual Solvents

□ The objective of this study was to identify significant formulation and processing variables affecting levels of tert-butyl alcohol (TBA) and isopropyl alcohol (IPA) in freeze-dried solids prepared from TBA/water cosolvent systems. The variables examined were the physical state of the solute (crystalline vs amorphous), initial TBA concentration, freezing rate, cake thickness, and the temperature and duration of secondary drying. Sucrose and glycine were used as models for noncrystallizing and crystallizing solutes, respectively. The TBA concentration above which eutectic crystallization takes place was determined by differential scanning calorimetry. Model formulations were subjected to extremes of freezing rate by either dipping in liquid nitrogen or by slowly freezing on the shelf of a freeze-dryer. Dynamics of solvent loss during secondary drying was determined by withdrawing samples as a function of time at different shelf temperatures using a thief system. On the basis of these studies, the most important determinant of residual TBA level is the physical state of the solute. Freeze-dried glycine contained very low levels of residual TBA (0.01–0.03%) regardless of freezing rate or initial TBA concentration. For freeze-dried sucrose, residual TBA levels were approximately 2 orders of magnitude higher and were significantly affected by initial TBA concentration and freezing rate. For the sucrose/TBA/water system, relatively low residual TBA levels were obtained when the initial TBA level was above the threshold concentration for eutectic crystallization of TBA, whereas samples freeze-dried from solutions containing TBA concentrations below this threshold contained significantly higher levels of TBA. Residual IPA levels increased continuously with initial concentration of TBA in the sucrose/TBA/water system. Formulations of sucrose/TBA/water which were frozen rapidly contained residual TBA levels which were approximately twice those measured in the same formulation after slow freezing and drying under the same conditions. For the sucrose/ TBA/water system, the temperature and time of secondary drying had only minimal influence on residual TBA in the freeze-dried solid. At low initial TBA concentrations (2%), residual TBA increases with increased cake thickness, perhaps because of the influence of depth of fill on effective freezing rate.

Power-law Relationship in Describing Temporal and Spatial Precipitation Pattern in Turkey

Wet and dry spell properties of monthly rainfall series at five meteorology stations in Turkey are examined by plotting successive wet and dry month duration versus their number of occurrences on the double-logarithmic paper. Straight line relationships on such graphs show that power-laws govern the pattern of successive persistent wet and dry monthly spells. Functional power law relationships between the number of dry and wet spells for a given monthly period are derived from the available monthly precipitation data. The probability statements for wet and dry period spells are obtained from the power law expressions. Comparison of power-law behaviours at five distinct sites in Turkey provides useful interpretation about the temporal and spatial rainfall pattern. As in temperate areas such as Turkey the rainfall amounts change mostly due to one-month-long dry or wet spells.

Un test d'humidification-séchage pour les blocs de terre comprimée et stabilisée au ciment

A method to characterise the durability of the cement-stabilised compressed earth blocks which TC 164-EBM is committed to developing is described in a report [1] presented at the 49th Technical Session of the RILEM General Council. The objective is to develop a wetting-drying test on cylindrical cement-stabilised compressed earth samples to determine the decrease in their compressive strength. This artificial ageing test is defined by three parameters: the duration of immersion, the duration of drying and the number of cycles. For the experimental approach to these three parameters, this method anticipates a study of the evolution of the compressive strength of 2 series of cylindrical samples having different strengths after curing, according to the duration of immersion, the duration of drying and the number of cycles. This report presents results for the constants: drying temperature (70°C) and relative humidity (40%).

Energy dispersive X-ray fluorescence spectrometry of major tissues of silky fowls.

This report is to survey elements in frozen or freeze-dried samples of major organs of silky fowls with energy dispersive X-ray fluorescence spectrometer (EDXRF). There was not essential difference between frozen and freeze-dried samples. Of major elements, P. S, K, and Cl were always detected and Mn, Fe, Ca, and Zn were detectable in certain organs. Iodine was detected in thyroid glands. Occasionally Br was detected. The duration of freeze drying, 24 hr or 7 days, did not make significant difference in elemental analysis.

Introduction of Statistical Treatment to Critical Heat Flux Model Based on Macrolayer Dryout.

prediction of pool boiling critical heat flux is studied in this paper. Statistical variances of macrolayer thickness and hovering period of vapor mass are introduced to the conventional macrolayer dry out model. Assumed thickness is twice as thick as the conventional model which coincides with those measured with electrical resistance probes. The effect of distribution function shape is investigated for different skewness factors, which indicates negligible effect even for superheat higher than the critical. As variance of either of hovering period or macrolayer thickness increases, boiling curve is rounded off at the top and critical heat flux decreases for the same averages. When the standard deviation is assumed to be 15-20% of mean value, predicted critical heat flux and dry duration ratio coincide with experiments. These facts show that the macrolayer dry out model is experimentally supported.

Tissue preparation for immunocytochemistry.

AIMS: To investigate the effect of tissue preparation on immunostaining and to establish whether there is a standard tissue preparation schedule that allows optimal demonstration of all antigens. METHODS: Blocks...

Development of a simulation tool to enable optimisation of the energy consumption of the industrial timber-drying process

Reducing the liquid content of green products is an important step in the manufacture of many products. Process conditions in the drying phase have significant influences on the quality of the end product and on energy consumption and required manufacturing time. Effective optimisation of the drying process requires accurate representation of the drying product and its interaction with its environment. The development of a computer simulation tool to analyse the industrial batch timber drying process is outlined. A detailed finite difference product model describing the heat and mass transfers within a plank during drying is described. It is integrated with a customised CFD code characterising the process conditions within the drying chamber. Simulation output from the integrated model is used to generate a macroscopic representation of the product in its drying environment. This representation is included as a component in a modular industrial installation simulation environment. Analysis with this global model can lead to optimisation of energy consumption of the industrial timber drying process whilst maintaining product quality and acceptable drying duration.