Different Types Of Bedding Research Articles

Cooling Effectiveness of the Sustainable Cooling Solution for Cattle: Case Study in Poland

Recently, the dairy sector has been ever more affected by global warming. This study aimed to test a novel conductive cooling system for cattle that was successfully implemented and evaluated under summer thermally challenging weather conditions in Poland. The system consists mainly of the chiller, tank, and chilled water-driven mattress, designed to prioritize animal well-being. The experimental evaluation was carried out on three Friesian dry cows, housed on different types of bedding—commercial water mattress, straw, and cooling water mattress—and supplied with water at 10 °C (day) and 16 °C (night). The cooling water mattress’ surface temperature was twice as low as that of the commercial water mattress. The animal’s thermal comfort was assessed with physiological and behavioral reactions. The cooling effect on animals’ bodies was demonstrated with a lower reticulorumen temperature of the cooled cow (p < 0.05) than the reference ones. The local effect of cooling was proved with an 8 °C-lower skin temperature after the cow’s resting period. The presented study opens a new research direction toward dairy cattle’s welfare, sustainability, and the food–energy–water nexus, based on potential energy and water savings.

Peculiarities of rearing poultry by floor method on deep bedding

In poultry rearing on deep bedding systems, microorganisms that cause infectious diseases develop within the bedding. This study aimed to determine the physical properties and microbial accumulation capacity of different types of bedding. Methods used included thermo-programmed desorption mass spectrometry, microbiological methods, and scanning electron microscopy. The hygroscopic properties of straw bedding deteriorated by 269.90% from the seventh to the fortysecond day. In the experimental room, where a dry disinfectant was added to the straw bedding, the hygroscopic capacity was 86.70% at the end of the experiment, a difference of 183.2%. Wood shavings bedding, with the addition of disinfectant, exhibited a water absorption capacity 102.82% higher than the control on the forty-second day. Granulated bedding with disinfectant retained moisture 150.33% better compared to the control. At the end of the experiment, the pH of straw bedding was 8.13 in the control group compared to 7.56 in the treated group; for wood shavings was 7.95 versus 7.16; and for granule was 7.35 versus 6.35, due to the use of the disinfectant. At the conclusion of the experiment, granulated bedding exhibited the lowest pH compared to straw and wood shavings, affecting the growth and reproduction of microorganisms. Monitoring of microorganisms in the bedding revealed the presence of bacteria: Escherichia coli, Salmonella typhimurium, Salmonella pullorum, Clostridium perfringens, Staphylococcus aureus, Klebsiella pneumonia, Listeria monocytogenes, as well as microscopic fungi: Fusarium sporotrichioides, Aspergillus niger, and Eimeria oocysts. The use of disinfectant reduced bacterial contamination of straw bedding by 12.35-199.19%, fungal contamination by 633.91-1959.14%, and Eimeria by 676.50%. In the wood shavings bedding, bacterial contamination was reduced by 32.84-257.93%, fungal contamination by 487.08-1098.4%, and Eimeria by 570.21%. Granulated bedding showed reduced bacterial accumulation by 50.93-228.87%, fungal accumulation by 169.89-500.9%, and Eimeria by 301.56%. The practical significance of this study lies in the improved physical properties of poultry bedding and the reduction in bacterial, fungal, and Eimeria oocyst accumulation

Research on the influence of stress on the penetration behavior of hydraulic fracture: Perspective from failure type of beddings

The failure types of bedding determine the penetration behavior of hydraulic fracture. A stratum model containing bedding was established based on the 3D block distinct element method to explore the penetration behavior of hydraulic fractures with different types of bedding. The mechanics of hydraulic fractures penetrating the shear- failure bedding plane and tensile-failure bedding plane were analyzed. The results showed that the shear-failure bedding plane was more difficult to expand than the tensile-failure bedding plane after the hydraulic fracture turns to bedding plane. The initial stress magnitude controls the expansion difficulty of hydraulic fractures, and the high stress magnitude attenuated penetration behavior. The vertical stress affected the shear failure by increasing the shear strength of the bedding plane. It affected the tensile failure by increasing the initiation stress of the bedding plane. The effect of horizontal stress on the penetration behavior included the influence on the initiation stress of vertical joints and the enhancement of the interference stress on the horizontal bedding plane. The conclusions can provide the guidance for hydraulic fracturing in reservoir with bedding planes.

The effects of different types of bedding on the performance, skeletal and behavioral characteristics, hygienic and immunity conditions of suckling Holstein calves

To investigate the effects of bedding types on the performance, skeletal and behavioral characteristics, health and immunity conditions of suckling Holstein calves, an experiment was conducted in a completely randomized design using 80 Holstein calves. The calves were distributed over 5 treatments and 4 replicates (each replicate included 2 male and 2 female calves). The 5 experimental treatments werechaff, straw, bagasse, sand, or mat. The results showed that the highest feed intake was related to the sand and chaff beddings and the highest weight gain (P<0.05) was found for the chaff, straw and sandbeddings . Withers height was highest and lowest for straw and mat treatments, respectively (P<0.05). The longest standing and resting times in calf behavior (P<0.05) were found for the sand and straw treatments, respectively. In cleanness, nose, eye, and joint scorings, the highest amount of con-tamination was related (P<0.05) to the mat and sand treatments . For immunity parameters, bagasse treatment showed the highest level of eosinophils (P<0.05) compared to the other treatments. Accord-ing to the results, it can be concluded that the straw bedding has better characteristics for growth, be-havior, and health of calves compared to the other beddings.

Beds, overlays and mattresses for preventing and treating pressure ulcers: an overview of Cochrane Reviews and network meta-analysis.

Beds, overlays and mattresses for preventing and treating pressure ulcers: an overview of Cochrane Reviews and network meta-analysis.

Water Production from Air Using Multi-Shelves Solar Glass Pyramid System.(Dept.M)

The capability of the glass pyramid shape with multi-shelf solar system to extract water from humid air is explored. Two pyramids were used with different types of beds on the shelves. The beds are saturated with 30% concentrated Calcium Chloride solution. The pyramid sides were opened at night to allow the bed saturated with moist air and closed during the day to extract the moisture from the bed by solar radiation. The bed in the first pyramid was made of saw wood while it is made of only clothes in the second pyramid with the same dimensions. The system was experimentally investigated at different climatic conditions to study the effect of pyramid shape on the absorption and regeneration processes. Preliminary results have shown that the cloths bed absorbs more solution (9 kg) as compared to the saw wood bed (8 kg), Adopting this approach produce 2.8 Liter/day.m2. The use of the pyramid shape with four glass surfaces and multi-shelves enhances the produced water by about 90-95 % compared with solar desiccant/collector system with horizontal and corrugated beds. Results shows also that the clothes bed has higher productivity than that of saw wood bed by about 5% This is due mainly to the greater carrying solution at the onset of the experimental work. The obtained results may help in designing more efficient system.

Bacterial concentrations in bedding and their association with dairy cow hygiene and milk quality

Comparison of bacterial counts (BCs) among common bedding types used for dairy cows, including straw, is needed. There is concern that the microbial content of organic bedding is elevated and presents risks for dairy cow udder health and milk quality. The objectives of this study were to investigate: (1) % DM and BCs (Streptococcus spp., all gram-negatives and specifically Klebsiella spp.) in different types of bedding sampled, and to investigate housing and farm management factors associated with % DM and BCs; (2) if bedding type was associated with hygiene of cow body parts (lower-legs, udder, upper-legs and flank) and housing and management factors associated with hygiene and (3) bedding types associated with higher BCs in cow milk at the farm level and bulk tank milk and management factors that were associated with highest BCs. Seventy farms (44 free-stall and 26 tie-stall) in Ontario, Canada were visited 3 times, 7 days apart from October 2014 to February 2015. At each visit, composite samples of unused and used bedding were collected for % DM determination and bacterial culture. Used bedding samples were collected from the back third of selected stalls. Data were analyzed using multivariable linear mixed models. Bedding classification for each farm were: new sand (n = 12), straw and other dry forage (n = 33), wood products (shavings, sawdust; n = 17) and recycled manure solids (RMSs)-compost, digestate (n = 8). In used bedding, across all bedding samples, sand was driest, compared to straw and wood, and RMS; higher % DM was associated with lower Streptococcus spp. count. Streptococcus spp. and all Gram-negative bacteria counts increased with increasing days since additional bedding was added. Gram-negative bacteria counts in used bedding varied with type: RMS = 16.3 ln colony-forming units (cfu)/mL, straw = 13.8 ln cfu/mL, new sand = 13.5 ln cfu/mL, and wood = 10.3 ln cfu/mL. Klebsiella spp. counts in used bedding were lower for wood products (5.9 ln cfu/mL) compared to all other bedding types. Mean cow SCC tended to be higher on farms with narrower stalls. Farms with mattress-based stalls had a higher prevalence of cows with dirty udders compared to those using a deep bedding system (often inorganic sand). Wider stalls were associated with lower bulk milk bacteria count. Lower % DM of used bedding was associated with higher bulk milk bacteria count. In conclusion, bedding management may have a profound impact on milk quality, bacterial concentrations in the bedding substrates, and cow hygiene.

Influence of bedding and backfill soil type on deformation of buried sewage pipeline

Abstract In the paper, the influence of different types of bedding and backfill soil surrounding underground sewage duct on its deformation was analysed. Impact of increased soil lateral pressure was examined by considering the construction of an embankment nearby the underground pipeline. Numerical computations of three different variants of bedding and backfill soil surrounding the pipe were carried out. Displacements and deformation of the pipe were calculated using the finite element method with adoption of elastic-perfectly plastic constitutive model of soil. Subsequent stages of the construction were taken into account. Shear strength reduction method was applied to evaluate the factor of safety of the entire system. Finally, the results and conclusions were depicted.

Cross-sectional study of the prevalence of and risk factors for hoof disorders in horses in The Netherlands

Information is scarce on the prevalence of hoof disorders in horses. In this study, we examined the prevalence of and risk factors for hoof disorders in a population of horses in The Netherlands. In a group of 942 randomly selected horses, hoof health was scored during regular foot trimming (one horse/farm). Hooves were assessed for the occurrence of one of 12 hoof disorders by a group of 21 certified farriers in two periods i.e. winter and summer of 2015.The mean age of the group of horses was 11.2±5.6years. They were mainly used for recreation (28.2%), dressage (26.8%), other disciplines (such as carriage driving and breeding) (18.7%), showjumping (17.6%) or combinations of these activities (8.6%). The horse farms studied were evenly distributed throughout the country. The horses were housed on different types of bedding, including straw (51.0%), shavings (17.5%), flax (16.1%) or other materials (11.0%), or were kept at pasture (4.4%).In 85% of the horses, at least one hoof disorder was observed during regular foot trimming. Most of the lesions were mild. The most frequently diagnosed hoof disorders were: thrush (T; 45.0%); superficial hoof wall cracks (SHWC; 30.4%); growth rings (GR; 26.3%); and sole bruises (SB; 24.7%). Less frequently observed hoof disorders included: perforating hoof wall cracks (PHWC; 16.4%); white line disease (WLD; 17.8%); and white line widening (WLW; 11.8%). Horizontal hoof cracks (5.2%), chronic laminitis (3.9%), quarter cracks (2.7%), keratoma (1.8%) and frog cancer (1.0%) were less frequently observed.Factors significantly associated with the occurrence of thrush comprised a wet stable floor (OR 1.6 and 2.9, for somewhat wet to wet respectively, compared to dry), the use of straw as bedding (OR=1.5, compared to flax), the housing strategy (e.g. permanent housing in contrast to permanent pasturing) (OR=1.7) and poor horn quality (OR=3.4). A higher prevalence of WLD was associated with less frequent hoof picking (OR=2.1 if performed weekly instead of daily), the use of flax bedding (OR=2.1, compared to straw) and poor horn quality (OR=8.1). A higher prevalence of SB was observed in horses used for multiple disciplines (OR=3.5, compared to dressage), with white-coloured hooves (OR=5.0, compared to black hooves), with longer intervals between trimming sessions (OR=4.8 in case of 8–10 weeks compared to weekly) and with poor horn quality (OR=5.4). A higher prevalence of WLW was observed in older horses (OR=15.5 for horses >19years, compared to <5years), in those with longer intervals between trimming sessions (OR=1.8 in case of 8–10 weeks compared to weekly), and in certain breeds (OR=3.2 for Friesian horses, 2.9 for Welsh ponies and 13.1 for Shetland ponies, all compared to Dutch Warmblood).In conclusion, although most of the hoof disorders identified were only in a mild stage, still an unexpectedly high prevalence of hoof disorders was observed during regular hoof trimming. Analysis of the data showed that some parameters, such as the use of flax bedding, may be protective for certain hoof disorders but a risk factor for others. This study provides useful guidelines for monitoring hoof health, reducing lameness and optimizing equine welfare.

Anatomical characteristics of teats and premilking bacterial counts of teat skin swabs of primiparous cows exposed to different types of bedding

Bacterial populations of teat skin are associated with risk of intramammary infection and may be influenced by anatomical characteristics of teats. The objective of this study was to evaluate associations of selected anatomical characteristics of teats with bacterial counts of teat skin of cows exposed to different types of bedding. Primarily primiparous Holstein cows (n = 128) were randomly allocated to 4 pens within a single barn. Each pen contained 1 type of bedding [new sand (NES), recycled sand (RS), deep-bedded manure solids (DBMS), and shallow-bedded manure solids over foam core mattresses (SBMS)]. During a single farm visit udders (n = 112) were scored for hygiene and 1 front (n = 112) and 1 rear teat (n = 111) of each enrolled cow were scored for hyperkeratosis (HK). Teat length, teat barrel diameter, and teat apex diameter were measured and teat skin swabs were systematically collected for microbiological analysis. Linear type evaluation data for udders of each cow were retrieved for each cow. Teat position (front or rear) was associated with occurrence of clinical mastitis during the 12 mo before the farm visit and more cases occurred in front quarters. The proportion of udders that were classified as clean (score 1 or 2) was 68, 82, 54, and 95% for cows housed in pens containing NES, RS, SBMS, and DBMS, respectively. No association was found between HK score and teat position and no association was found between HK score and teat skin bacterial count. Bacterial counts of teat skin swabs from front teats of cows in pens containing RS and SBMS were significantly less than those of rear teats of cows in pens containing DBMS or NES. Teat skin bacterial counts were significantly greater for swabs obtained from teats of cows with udder hygiene scores of 3 and 4 as compared with swabs obtained from cows with cleaner udders. Of all udder conformation traits evaluated, only narrower rear teat placement was positively associated with bacterial counts on teat skin.

Flow dynamics on a porous medium

In this paper, which can be regarded as a companion of that by Corvaro et al. (2010), experimental results on the internal flow kinematics of waves which propagate on different types of beds, focusing on the nearbed dynamics induced by a porous bed, are illustrated and analyzed. The porous bed induces a major attenuation in the upstream-to-downstream direction of both wave height (≈30%) and internal flow velocity (≈50% for the maximum and minimum phases). The relationship between the wave height and the internal flow attenuation has been analyzed by means of wave energy arguments. We also found that the averaged reduction of mean flow between the smooth and porous-bed cases is approximately of 45% and 55%, respectively, for the horizontal and vertical velocity components. The stronger reduction of the vertical velocity is due to a significant variation of this velocity profile with respect to what occurs on an impermeable bed. An optical technique is used to extract the flow velocity from suitable video images; the wave dynamics on the porous medium is analyzed by evaluating the mean wave flow, the turbulence and the vorticity fields over the layer. The turbulence, indirectly characterized in terms of instantaneous velocity spectra, is found to be largely confined within the bottom boundary layer, located at a position deeper than the peaks of the mean flow. From the analyses of the instantaneous velocity spectra a clear anisotropy and inhomogeneity are found for the nearbed turbulence. This is confirmed by the presence, in the bottom boundary layer, of elongated coherent vortical structures whose intensity is the maximum during the wave crest and trough phases.

Husbandry risk factors associated with hock pododermatitis in UK pet rabbits (Oryctolagus cuniculus)

Pododermatitis, often called ‘sore hocks’, is a chronic, granulomatous, ulcerative dermatitis which most commonly affects the plantar aspect of the caudal metatarsal and tarsal areas. Pododermatitis is a common clinical...

Gas and particle concentrations in horse stables with individual boxes as a function of the bedding material and the mucking regimen1

The aim of this study was to compare different types of bedding and mucking regimens used in horse stables on the generation of airborne particulate matter <10 microm (PM10) and 3 biogenic gases (carbon dioxide, nitrous oxide, and especially ammonia). Three separate experiments were undertaken. The experiments were carried out in an enclosed stable (9.7 m long, 8.7 m wide, and 3.5 m high) that had 5 single boxes housing 4 horses. The measuring instruments were set up in the middle of one side of the stable. In Exp. 1, 3 types of bedding material (wheat straw, straw pellets, and wood shavings) used for horses were assessed according to their ammonia generation. Each type of bedding was used for 2 wk, with 3 repetitions. The mean ammonia concentrations within the stable were 3.07 +/- 0.23 mg/m(3) for wheat straw, 4.79 +/- 0.23 mg/m(3) for straw pellets, and 4.27 +/- 0.17 mg/m(3) for wood shavings. In Exp. 2, the effects of the mucking regimen on the generation of ammonia and PM10 from wheat straw (the bedding with the least ammonia generation in the previous experiment) were examined using 3 different daily regimens: 1) no mucking out, 2) complete mucking out, and 3) partial mucking out (removing only feces). The mean ammonia concentrations in the stable differed significantly among all 3 mucking regimens (P < 0.05). The greatest values were recorded when the stalls were mucked out completely every day [least squares means (LSM) = 2.25 +/- 0.1 mg/m(3)]. No mucking out resulted in an LSM of 1.92 +/- 0.1 mg of ammonia/m(3), whereas an LSM of 1.54 +/- 0.1 mg of ammonia/m(3) was found when the partial mucking out method was used. No mucking out also resulted in significantly less average PM10 (124.4 +/- 13.4 microg/m(3)) than in the other 2 regimens (P < 0.05). In Exp. 3, a 6-wk bedding regimen without mucking out was evaluated with regard to gas and airborne particle generation. The ammonia values were found not to increase constantly during the course of the 6-wk period. The average weekly values for PM10 also did not increase constantly but varied between approximately 90 and 140 microg/m. It can be concluded from the particle and gas generation patterns found in the results of all 3 experiments that wheat straw was the most suitable bedding of the 3 types investigated and that mucking out completely on a daily basis should not be undertaken in horse stables.

The Pavlovian power of palatable food: lessons for weight-loss adherence from a new rodent model of cue-induced overeating

ObjectiveRelapsing to overeating is a stubborn problem in obesity treatment. We tested the hypothesis that context cues surrounding palatable food (PF) intake have the power to disrupt caloric regulation even of less PF. Context cues are non-food cues that are in the environment where PF is habitually eaten.DesignRats were conditioned to associate intake of Oreo cookies as the PF to cages with distinct context cues that differed from cues in cages were they were only given chow. PF naturally stimulated greater caloric intake. The rats were then tested in the PF cage with only chow available to determine if the PF-paired cues, alone, could elicit overeating of plain chow.SubjectsNon food-deprived female Sprague-Dawley rats.MeasurementsIntake of plain chow under PF-paired cues vs. chow-paired cues was compared. This was also measured in tests that included a morsel of PF as a priming stimulus. We also controlled for any effect of binge-prone vs. binge–resistant status to predict cued-overeating.ResultsRats consumed significantly more chow when exposed to context cues previously paired with PF than with chow (p<0.01). This effect occurred using various cues (e.g., different types of bedding or wallpaper). The effect was strengthened by priming with a morsel of PF (p<0.001) and was unaffected by baseline differences in propensity to binge on PF.ConclusionContext-cues associated with PF intake can drive overeating even of a less PF and abolish the ability of rats to compensate for the calories of a PF primer. Just as drug-associated context cues can reinstate drug-addiction relapse, PF-paired cues may trigger overeating relapses linked to weight regain and obesity. This model should help identify the reflex-like biology that sabotages attempts to adhere to healthy reduced calorie regimens and call greater attention to the cue-factor in the treatment of binge-eating and obesity.

Water production from air using multi-shelves solar glass pyramid system

The capability of the glass pyramid shape with a multi-shelf solar system to extract water from humid air is explored. Two pyramids were used with different types of beds on the shelves. The beds are saturated with 30% concentrated Calcium Chloride solution. The pyramid sides were opened at night to allow the bed saturated with moist air and closed during the day to extract the moisture from the bed by solar radiation. The bed in the first pyramid was made of saw wood while it is made of only cloth in the second pyramid with the same dimensions. The system was experimentally investigated at different climatic conditions to study the effect of pyramid shape on the absorption and regeneration processes. Preliminary results have shown that the cloths bed absorbs more solution (9 kg) as compared to the saw wood bed (8 kg). Adopting this approach produces 2.5 L/day m 2. The use of the pyramid shape with four glass surfaces and multi-shelves enhances the produced water by 90–95% compared with solar desiccant/collector system with horizontal and corrugated beds. Results also show that the clothes bed has higher productivity than that of saw wood bed by about 5%. This is due mainly to the greater carrying solution at the onset of the experimental work. The obtained results may help in designing more efficient system.

The formation of a suspension bed on dual flow distributors

The formation of suspension beds on a dual flow distributor was studied using mono-sized particles (group D, Geldart, 1973). Three stages are experienced during the formation of a suspension bed: the induced, the growing and the final stage. The discharge mechanisms are raining, weeping, dumping (I) and dumping (II). The operating variables of a suspension bed are the opening ratio of the distributor ( m), the solids feeding rate ( F), the normalised air velocity through the hole ( U o/ U t, where U t is the terminal velocity of a single sphere in the air), the ratio of the diameter of the hole of the perforated plate to the size of the particle ( d o/ d p), and the density of the particles ( ρ p). Their influences on the formation of a suspension bed were examined. Five different types of beds were formed depending on the combination of the operating variables; these can be catagorised as dilute beds, oscillating shallow beds, bubbling beds, slugging beds and flooding beds. The ranges for stable operating conditions using 2-mm polystyrene spheres are mapped, which have the following ranges: 0.31≤ m≤0.52; 0.082 kg/s·m 2≤ F≤0.455 kg/s·m 2 and 0.8≤ U o/ U t≤1.25. A model was developed to simulate the growth of the bed in terms of the net pressure drop across the bed. There is a good qualitative agreement between the experimental pressure drop and model predictions.

Relationship between the conditions of lower airways in healthy horses, environmental factors and air quality in stables

In 6 healthy Haflinger horses stabled in individual boxes, different types of bedding (husk, straw and woodshavings) and hay (dry and soaked) were periodically changed. After each test period (45 days) bronchoalveolar lavage (BAL) was carried out for each horse, and the BAL fluid (BALF) withdrawn was submitted for citological and microbiological evaluation. The environmental dust burden was evaluated by means of an air filtration system and an optical counter with laser diode. Dust particles were sorted in eight size classes ranging from 0.3 to >20 μm. Qualitative evaluation of dust components was achieved by means of a Surface air system sampler (Sas). Total dust, which ranged from 0.03 mg/m3 to 0.40 mg/m3, prooved highly related with mast cell differential count (r = 0.61; P = 0.03). Besides, BALF mastcells differential count decreased significantly when hay was soaked. BALF alveolar macrophages showed a negative relationship with particles ranging from 1 to 2 μm (r = –0.55; P = 0.05) and from 2 to 5 μm (r = –0.61; P = 0.03), considered as respirable fraction (RF). It was concluded that even in healthy horses the investigated factors may play an important role in lower airways condition.

Sheepskins and bedding in childhood, and the risk of development of bronchial asthma

Sheepskin bedding might increase house dust mite exposure and so explain some of the increasing prevalence of severity of childhood asthma. Relationships between use of different types of bedding, and diagnoses of asthma, symptoms of wheezing, skin prick test evidence of house dust mite sensitivity, and airway responsiveness to methacholine, were examined retrospectively in a birth cohort of children followed longitudinally to age 15 years. In the whole cohort, no associations were identified to suggest a causal relationship between use of any type of bedding and development of features of asthma. Although not an a priori hypothesis, we noted that among children with a family history of atopic disease, those who were house dust mite sensitive were more likely to have used an innerspring mattress (29.6% vs 10.2% who had not used an innerspring mattress, p = 0.005). In this subgroup, increased airway responsiveness and mite sensitivity were significantly associated with use of innerspring mattresses, although whether this is a causal or secondary association is not certain. Use of a sheepskin in the bed in early childhood was not an additional risk factor for the development of asthma.

Fire testing of bed assemblies of reduced flammability

Bed assemblies of reduced flammability and suitable for hospital use were evaluated in triplicate, full-scale burning tests in a room corridor test rig. Smoke temperatures, volume and density, and carbon monoxide, carbon dioxide and oxygen concentrations were recorded continuously. The composition of the bed assemblies was varied to assess different types of bedding (polyester, modacrylic and flame-retarded cotton), mattresses (DHSS contract and PU barrier foam types) and bed bases (wire and solid supports). A limited test programme was carried out with non-fire-retardant cotton bedding and pillow cases.

A GENERALIZED APPROACH TO FLOW THROUGH FIXED BEDS FLUIDIZATION AND HINDERED SEDIMENTATION

A generalized approach for a unified description of flow through mono and polydisperse uniform fixed and distended beds, particulate fluidization and hindered sedimentation is presented. Drag forces exerted by fluids on individual particles are used to evaluate friction factors and pressure drops across fixed beds. Extended definitions of drag coefficient and of its correlation with Reynolds number are evaluated and compared with literature data. It is shown that the new approach can be used reliably for creeping and turbulent flows, and also that it applies to the full range of packing densities which characterize dispersions and different types of beds comprising spherical particles. Finally effect of size distribution, bed structure, and particle segregation, on pressure drop, and implication of the new model for analysis of onset of fluidization are considered.