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PubMed2001

Dynamic light scattering measurements of particle size development in aqueous humic materials.

Dynamic light scattering (DLS) has been used to monitor changes in aggregate sizes of aqueous humic materials as a function of solution properties. Humic and fulvic acids were dissolved at relatively low concentrations (15-30 mg L(-1)) in solutions of different temperature, cation and ethanol content, and pH. The results could be explained in terms of intramolecular contraction and intermolecular aggregation of humic polymers. The former were prevalent in soil humic acids, and less so in aquatic humic acids and fulvic acids. Increasing the temperature of humic solutions generally led to an increase in particle sizes, which was ascribed to an effect akin to surfactant clouding. The addition of cations led to either contraction or expansion, depending on the charge and concentration of the ion, and the nature of the humic material. Reducing the pH initially caused contraction, followed by growth and precipitation in more highly acidic media.

Benzopyrans↗

PubMed1985

Drug absorption from inhalation aerosols administered by positive-pressure ventilation. II: Effect of disodium fluorescein aerosol particle size on fluorescein absorption kinetics in the beagle dog respiratory tract.

Solid, polydispersed disodium fluorescein aerosols (MMDae = 1.1, 3.5, and 4.4 micron) were administered under the same respiratory regime, direct to the respiratory tracts of two beagle dogs by positive-pressure ventilation. Subsequent to aerosol administration, plasma fluorescein concentrations were determined after sampling from an indwelling cannula. The amount absorbed as a function of time was estimated from these and additional data collected from intravenous control experiments in the same animals. Fluorescein absorption from the respiratory tract was apparently a first-order process, the rate increasing directly with the bioavailable dose. First-order rate constants differed but appeared unrelated to aerosol particle size, possibly reflecting similarities in their regional deposition in the canine lung. The average value for the absorption half-lives in the dogs were 19.3 and 12.2 min, showing that even lipophobic solutes such as the fluorescein dianion, are absorbed extremely rapidly via the lung. In one dog, the rate constant for fluorescein absorption after intratracheal instillation of a solution of the disodium salt was within the range of those following aerosol administration. Possible explanations are discussed.

Absorption↗

PubMed2003

Effect of improving glycemic control on low-density lipoprotein particle size in type 2 diabetes.

The current study sought to assess the effect of improving glycemic control in type 2 diabetes on the components of diabetic dyslipidemia, especially low-density lipoprotein (LDL) size. A total of 33 type 2 diabetic patients (48.5% women, age 59.6 +/- 11.1 years, body mass index [BMI] 28.9 +/- 4.9, diabetes duration 6 [0 to 40] years, 40.7% on insulin) were seen at the hospital because of poor glycemic control (hemoglobin A(1c) [HbA(1c)] 10.33% +/- 1.89%). Triglyceride, LDL-cholesterol (LDLc, Friedewald/ ultracentrifugation), high-density lipoprotein HDL-cholesterol (HDLc, direct method), apolipoproteins AI (apoAI) and B (apoB) (immunoturbidimetry), and LDL size (gradient gel electrophoresis) were measured at baseline and after improvement in glycemic control (decrease >/= 1 percentage point in HbA(1c) and final HbA(1c) </= 8%). Improvement in glycemic control (HbA(1c) 7.01% +/- 0.63%, P <.0005 v baseline) after a follow-up of 3.5 (range, 1 to 13) months resulted in a significant reduction in LDLc (3.34 +/- 1.02 v 3.62 +/- 1.15 mmol/L, P <.05) and apoB (1.07 +/- 0.25 v 1.17 +/- 0.29 g/L, P <.01) and an increase in HDLc (1.21 +/- 0.32 v 1.13 +/- 0.34 mmol/L, P <.05) and apoAI (1.36 +/- 0.24 v 1.27 +/- 0.24 mmol/L, P < 0.01) in the whole group, and an increase in LDL particle size (25.61 +/- 0.53 v 25.10 +/- 0.31 nm, P <.005) in the 14 patients showing LDL phenotype B at baseline. No significant changes were seen in body weight or BMI. We conclude that improvement of glycemic control in type 2 diabetes improves most of the components of diabetic dyslipidemia, including a shift towards larger LDL particles in subjects with phenotype B.

Aged↗

PubMed2001

Smaller LDL particle size in women with polycystic ovary syndrome compared to controls.

OBJECTIVE: Women with polycystic ovary syndrome (PCOS) have an increased risk of cardiovascular disease. The contribution of lipid abnormalities to this higher risk, in particular atherogenic modifications of low density lipoprotein (LDL) such as a shift towards smaller LDL, has not been properly explored. We aimed to examine LDL size variation in relation to androgens and other risk factors in women with PCOS. DESIGN: Comparison of clinical and biochemical measurements in women with PCOS and women with normal ovarian function, of similar age and body mass index (BMI). PATIENTS: Thirty-one women with PCOS and 27 controls were studied. Patients were recruited from the outpatient endocrine clinic. MEASUREMENTS: Fasting total cholesterol, triglycerides (TG), high density lipoprotein (HDL), LDL, glucose, insulin, gonadotrophins, androgens, oestradiol, 17 OH progesterone and SHBG were measured. LDL particle diameter was calculated based on distance travelled in polyacrylamide native gels. Recumbent blood pressure was measured automatically. RESULTS: LDL particle size appeared to be significantly smaller in hyperandrogenic PCOS as compared to regularly cycling women (P = 0006), independent of variations in lipid levels. SHBG was the only independent predictor of LDL size in this population, with a strong correlation, which persisted after adjustment for all confounding variables. CONCLUSIONS: Our results suggest that androgen excess and mild insulin-resistance (both responsible for lower SHBG) may have an early modifying effect on low density lipoprotein size in polycystic ovary syndrome women. The denser pattern observed in polycystic ovary syndrome women could by itself constitute a higher cardiovascular risk, even in the absence of overt dyslipidaemia, and contribute to the excess risk of cardiovascular disease reported in this syndrome.

Adult↗

PubMed2002

The relationship of particle size to olfactory nerve uptake of a non-soluble form of manganese into brain.

The essential element, manganese, can produce chronic neuromotor impairment related to basal ganglia (BG) damage when it is presented in excessive quantities. The uptake and elimination patterns of manganese following ingestion have been well studied and, under normal conditions, excretion appears to keep manganese levels under tight control. Less is known about inhalation exposure, but it has been proposed that the lung might serve as a long-term reservoir for manganese transport into blood. Recent data suggest that a third route of exposure, transport by the olfactory nerve directly to the brain, might have importance in toxicology since such a route would bypass liver uptake and biliary excretion of manganese. In this study, we sought to determine how particle size and the use of a poorly soluble form of manganese might influence net systemic absorption of manganese dust and the potential role of the olfactory nerve in transport of manganese dioxide. Rats were exposed in nose-only exposure chambers to manganese dioxide (MnO2) aerosols of 1.3 and 18 microm mass median aerodynamic diameter (MMAD). The concentration of aerosols was kept constant at 3 mg/m3 as Mn. Following 15 days of exposure (five times per week for 3 weeks), rats were euthanized and tissues harvested for manganese determination carried out by graphite furnace atomic absorption spectroscopy. Small-particle MnO2 exposure resulted in an elevation in olfactory bulb manganese concentration, presumably through uptake by the olfactory nerve, but the effect was highly variable. While small increases in cortical and neostriatal manganese levels were also observed in these rats, they did not reach statistical significance. By contrast, there was no evidence of olfactory nerve MnO2 uptake in rats receiving the large-particle exposure.

Administration, Inhalation↗

PubMed1997

Beneficial effects of alcohol withdrawal on LDL particle size distribution and oxidative susceptibility in subjects with alcohol-induced hypertriglyceridemia.

LDL subclass pattern B, reported to have a higher prevalence in hypertriglyceridemics (HTGs), is considered to be associated with an increased risk for coronary artery disease, and the small dense LDL characteristic of this pattern is susceptible to oxidative modification. Alcohol is considered one of the most frequent causes of increases in plasma triglyceride (TG) levels. We investigated the effects of alcohol withdrawal on LDL subclass distribution and oxidizability in drinkers with different plasma TG levels. Thirty-seven male subjects with relatively heavy alcohol-consumption habits were divided into four groups; normotriglyceridemic (NTG)/withdrawal (n = 11), NTG/control (n = 8), hypertriglyceridemic (HTG)/withdrawal (n = 10), and HTG/control (n = 8). Both withdrawal groups abstained form alcohol for 4 weeks, while the control subjects maintained their usual intake of alcohol. Peak LDL particle diameter (PPD) was smaller in the combined HTG groups than in the combined NTG groups before abstinence, although PPD increased significantly (P < .01) from 25.5 to 26.1 nm in the HTG/withdrawal group. Before abstinence, lag times preceding LDL oxidation in the combined HTG groups were shorter than in the combined NTG groups; after withdrawal, lag time was prolonged significantly (P < .01) from 49.9 to 57.3 minutes in the HTG-withdrawal group. No significant changes in PPD and lag time were observed in the other three groups. Significant correlations (P < .05) were observed between the change (delta) in the lag time and delta TG and between delta lag time and delta PPD. We conclude that in alcohol-induced HTG subjects, alcohol withdrawal has beneficial effects on the LDL profile by shifting the particle size from smaller to larger and decreasing its susceptibility to oxidation.

Adult↗

PubMed2004

Intake, ingesta retention, particle size distribution and digestibility in the hippopotamidae.

Although several aspects of the digestive physiology of the hippopotamidae-non-ruminating foregut fermenters-have been described, ingesta kinetics and passage characteristics of these species are not well understood. The most outstanding feature of the hippo digestive physiology reported so far is the very long mean ingesta retention times (MRTs) measured by Foose [Foose, T., 1982. Trophic strategies of ruminant versus nonruminant ungulates. PhD dissertation, University of Chicago, Chicago.]. Since those data had been investigated with animals without water access, we intended to measure MRT in hippos which were allowed to enter water pools during the night. MRT parameters as well as dry matter (DM) digestibility were determined in four common (Hippopotamus amphibius) and four pygmy hippos (Hexaprotodon liberiensis) on two different diets each using cobalt ethylendiamintetraacetate (Co-EDTA) as a fluid, chromium (Cr)-mordanted fibre (<2 mm) as a particle and acid detergent lignin (ADL) as an internal digestibility marker. Four of the animals additionally received cerium (Ce)-mordanted fibres (2-10 mm) as particle markers. Total MRTs for fluids and particles ranged between 20-35 and 48-106 h in the common and between 13-39 and 32-107 h in the pygmy hippos. The difference between fluid and particle retention was greater than usually reported in ruminants. Excretion patterns of the markers differed from those usually observed in ruminants but resembled those reported for macropods (kangaroos), indicating a plug-flow reactor-like physiology in the hippo forestomach (FRST). This finding complements other described similarities between the macropod and the hippo forestomach. The measurements of larger particle retention profiles suggest that in the hippo, larger particles might be excreted either faster or at the same rate as smaller particles, indicating a general difference between ruminants and hippos with respect to differential particle retention. The digestive physiology of hippos is characterised by a generally low food intake, long ingesta retention times and dry matter digestibilities lower than reported in ruminants. Moderate digestibilities in spite of long retention times might be the result of the generally high average ingesta particle size in hippos. The comparatively easy management of pygmy hippos, together with the significant correlations between food intake, MRT and digestibility in the pygmy hippos of this study, recommends this species for further studies on the interplay of these parameters in herbivore digestive physiology.

Animals↗

PubMed1988

Changes of HDL subfraction concentration and particle size by intralipid in vivo.

The effects of the artificial triglyceride-phospholipid emulsion (10% intralipid) on HDL subfraction were studied in vivo. After a 14-h fast, subjects received intralipid via a 4-h infusion. Serum lipoproteins were analyzed before and at 4 and 6 h after the start of the infusion. At 4-h the following acute changes by infusion were observed. Triglyceride, phospholipid, free cholesterol, and esterified cholesterol in chylomicrons and VLDL increased. HDL2 as well as triglyceride, phospholipid, free cholesterol and protein within the HDL2 increased, while HDL3 decreased. An increase in HDL3 triglyceride was observed. The masses of apo A-I and A-II in the HDL2 density interval rose while these parameters fell in HDL3. There were decreases of apo C-II and C-III in the HDL subfractions and elevations in chylomicrons and VLDL. The particle size of the HDL subfractions increased. However, most of these acute changes at 4 h tended to disappear by 6 h. These results suggest that there is exchange of lipids and reversible transfer of apo C-II and C-III between HDL subfractions and intralipid, and conversion of HDL3 to HDL2 followed by the reverse conversion of HDL2 to HDL3 as the synthetic emulsion is cleared from the plasma.

Adult↗

PubMed2006

Rosiglitazone increases LDL particle size and buoyancy and decreases C-reactive protein in patients with type 2 diabetes on statin therapy.

A substantial number of individuals with type 2 diabetes mellitus (T2DM) demonstrate a predominance of small dense low-density lipoprotein (sdLDL), which is associated with an increased risk of cardiovascular disease (CVD). In some cases, sdLDL persists after treatment with a statin to reduce levels of LDL. The effect of the addition of a thiazolidinedione, rosiglitazone (RSG) (4 mg/day or 8 mg/day) to statin therapy on LDL phenotype and C reactive protein (CRP) levels was investigated in a 12- week, placebo-controlled study of 72 T2DM patients who were well controlled and on a statin, but who had persistently predominant sdLDL. Addition of RSG 8 mg to statin therapy significantly increased LDL buoyancy (relative flotation +0.014, p = 0.003) and LDL particle size (+4.2A, p = 0.001) from baseline and relative to the change with placebo (+0.014 and +3.8A; p = 0.03 and p = 0.04, respectively), and was associated with a non-significant decrease in sdLDL. RSG 8 mg moderately, but significantly, increased total cholesterol (by 12.2%, p = 0.004), LDL-cholesterol (11.2%, p = 0.02) and intermediate-density lipoprotein (IDL)-cholesterol from baseline but did not increase total or LDL apolipoprotein B. RSG 4 mg and 8 mg significantly reduced CRP compared with placebo (-44.9% and -48.0%; p = 0.008 and p = 0.004, respectively), and significantly reduced insulin resistance and fasting plasma glucose from baseline. Addition of RSG to statin therapy may further reduce cardiovascular risk by improving the LDL phenotype, as well as reducing insulin resistance and CRP levels. However, the increase in IDL may be proatherogenic and must be considered when assessing the benefits of rosiglitazone.

Blood Glucose↗

PubMed1996

Availability for poults of phosphorus from meat and bone meals of different particle sizes.

Two experiments were conducted to compare the dietary availability of P from meat and bone meal (MBM) with that of P from dicalcium phosphate (DP) for poults. Two batches of the same MBM were tested. The batches differed in fineness of grind; one was passed through a 10-mesh screen (openings of 2.03 mm) (MBM1O) and the other through a 12-mesh screen (openings of 1.91 mm) (MBM12). In Experiments 1 and 2, the low-P basal diets contained, by analysis, 0.54% P (0.2% nonphytate P) and 0.64% P (0.3% nonphytate P), respectively. Each batch of MBM and DP were included in isocaloric, equinitrogenous diets to obtain increments of 0.1, 0.2, 0.3, and 0.4% P added to the basal diet. Three pens, each containing seven poults, were assigned to each of the 13 dietary treatments. Poults were fed the diets from 5 to 11 and 6 to 13 d of age in Experiments 1 and 2, respectively. Regression analyses of the data showed that increases in BW and tibia ash were linearly related (P </= 0.01) to percentage dietary P and to quantity of P consumed. Common intercept multiple linear regression was used to derive relative availabilities (RA) with DP assigned a value of 100. On the basis of BW gains, RA of MBM1O and MBM12 ranged from 99.1 to 105.5, depending on the independent variable and the experiment. Similarly, on the basis of tibia ash, RA ranged from 97.3 to 104.8. None of the RA differed (P > 0.05) from 100. Thus, the RA of P from MBM tested were equal to that of P from DP, and particle size of the MBM did not affect RA of P.

Animals↗

PubMed2006

Critical particle size for fractionation by deterministic lateral displacement.

The fractionation of small particles in a liquid based on their size in a micropost array by deterministic lateral displacement was recently demonstrated with unprecedented resolution (L. R. Huang, E. C. Cox, R. H. Austin and J. C. Sturm, Science, 2004, 304, 987-990, ). In this paper, we present a model of how the critical particle size for fractionation depends on the micropost geometry, depending specifically on the gap between posts, the offset of posts in one row with respect to another, and whether the fluid is driven by hydrodynamics or by electroosmosis. In general the critical particle diameter is much smaller than the gap, which prevents clogging. The model is supported by data with particles from 2.3 to 22 microm.

Chemical Fractionation↗

PubMedDate not supplied

Particle size characterizations of copper and zinc oxide exposures of employees working in a nonferrous foundry using cascade impactors.

This study characterized exposures to copper and zinc oxide as respirable or nonrespirable using personal impactors and compared the results with previous findings obtained using cyclones. Twenty-five sets of air samples were taken over a 10-month period using single jet cascade impactors. Five to six stages were used to capture and classify aerosols according to their aerodynamic diameter (d(ae)). These ranged from < 0.5 microm to > 10 microm d(ae). Twenty-two air samples were taken on employees casting brass alloys, and three samples were taken in areas in the vicinity where employees routinely worked. Twenty-one air samples were taken during the casting of a single brass alloy (containing 70% copper and 30% zinc), and the remaining samples were obtained from employees casting two different brass alloys: a nearly pure copper alloy and a nickel-copper alloy. The results indicated that 55-96% (by mass) of all copper aerosols collected had a d(ae) > or = 10 microm. More than 85% (by mass) of all copper exposures were estimated as nonrespirable using the current ACGIH-CEN-ISO definition. Zinc oxide aerosols were collected at all stages of the impactors, with significant amounts found to have a d(ae) > or = 10 microm. More than 60% (by mass) of all zinc oxide exposures were estimated to be nonrespirable. A comparison of data collected using impactors and cyclones demonstrated that cyclones could be used to differentiate larger aerosol particles from fumes, rather than requiring the use of impactors. It is recommended that appropriate particle size selective sampling methods be used to classify exposures of metals to dusts and fumes.

Aerosols↗

PubMed2005

A new immunomodulatory function of low-viscous konjac glucomannan with a small particle size: its oral intake suppresses spontaneously occurring dermatitis in NC/Nga mice.

BACKGROUND: Konjac glucomannan (GM) is a well-known dietary fiber with various beneficial functions: the higher viscosity displayed the stronger potency. However, the high-viscous GM powders, ordinary konjac powder and highly purified GM were mostly unsuitable for the application to various food industries. Our aims are to develop new physiological functions of low-viscous GM powder, pulverized GM or re-granulated fine GM, using a murine model of atopic dermatitis. METHODS: Male 4-week-old NC/Nga mice were fed for 8 weeks on diets containing 5% of two high-viscous and two low-viscous GM powders, respectively. RESULTS: Striking suppression against the aggravation of dermatitis, the increase in scratching behaviors, and the rise in IgE levels was recognized only in mice fed on the pulverized GM diet, but not in mice fed on the other GM diets or a control diet. Eczema prevention in the fine GM-fed mice was accompanied by a significant decrease in their plasma IFN-gamma levels, a positive regulatory cytokine for atopic skin inflammation. CONCLUSION: Only the pulverized GM possessed the ability to suppress the development of dermatitis in NC/Nga mice. This is the new immunomodulatory function of low-viscous GM with a small particle size.

Administration, Oral↗

PubMed1998

Effect of particle size and charge on the disposition of lipid carriers after intratumoral injection into tissue-isolated tumors.

PURPOSE: Pharmacokinetic properties of various lipid carriers (liposome and emulsions) after intratumoral injection were studied in perfusion experiments using tissue-isolated tumor preparations of Walker 256 carcinosarcoma. METHODS: Four types of lipid carriers, large emulsion (254 nm), small emulsion (85 nm), neutral liposomes (120 nm) and cationic liposomes (125 nm) were prepared. We quantified their recovery from the tumor, leakage from the tumor surface and venous outflow after intratumoral injection into perfused tissue-isolated tumors, and analyzed venous appearance curves based on a pharmacokinetic model. RESULTS: In contrast to the small emulsion and neutral liposomes, which immediately appeared in the venous outflow perfusate following intratumoral injection, the appearance of the cationic liposomes and the large emulsion was highly restricted, clearly demonstrating that intratumoral clearance of these formulations can be greatly retarded by the cationic charge and large particle size, respectively. The venous appearance rate-time profiles were fitted to equations derived from a two-compartment model by nonlinear regression analysis. When the calculated parameters were compared among these four formulations, the venous appearance rate did not exhibit such a large difference; however, the rate of transfer from the injected site to the compartment which involves clearance by venous outflow was all very different. CONCLUSIONS: The results of this study indicate that the determining factor which alters the pharmacokinetic properties of these lipid carriers after intratumoral injection is not the rate of transfer from the interstitial space to the vascular side but the rate of intratumoral transfer from the injection site to the well-vascularized region.

Animals↗

PubMed1999

The effect of particle size of whole-grain flour on plasma glucose, insulin, glucagon and thyroid-stimulating hormone in humans.

OBJECTIVE: Although it is well known that consumption of whole-grain foods with higher fiber content results in beneficial health effects, most Americans usually prefer bread made with white flour. Changes in bread texture and undesirable intestinal responses have been reported as reasons for avoiding consumption of whole-grain foods or high-fiber menus. The purpose of this study was to determine whether consumption of bread made with ultra-fine-ground whole-grain wheat flour retained beneficial effects while reducing undesirable effects. METHODS: Twenty-six men and women, 31 to 55 years of age, consumed glucose solutions or bread made with traditional white, conventional whole-grain wheat (WWF), or ultra-fine whole-grain wheat (UFWF) flour (1 g carbohydrate/kg body weight) in a Latin square design after two days of controlled diet. The effect on glycemic response was determined by comparing blood variables, after a tolerance test with white bread, WWF bread, and UFWF bread, with those after a glucose tolerance test. RESULTS: Men and women had similar responses to all tolerances except postprandial TSH. Glucose and insulin levels one half hour after the glucose load were significantly higher than after any of the bread tolerances. Glucose, but not insulin, areas under the curve were significantly higher after the glucose load than areas after the three breads. Consumption of UFWF resulted in glucose and insulin responses, as well as areas under the curve, similar to those after consumption of conventional whole-wheat bread. CONCLUSION: The particle size of whole grain wheat flour did not substantially affect glycemic responses.

Adult↗

PubMed2006

Influence of particle size on the quantitative determination of salicylic acid in a pharmaceutical ointment using FT-Raman spectroscopy.

A second order polynomial calibration model was developed and statistically validated for the direct and non-destructive quantitative analysis - without sample preparation - of the active pharmaceutical ingredient (API) salicylic acid in a pharmaceutical ointment using FT-Raman spectroscopy. The calibration curve was modeled by plotting the peak intensity of the vector normalized spectral band between 757 and 784cm(-1) against the known salicylic acid concentrations in standards. At this band, no spectral interferences from the ointment vehiculum (white vaseline) are observed. For the validation of the polynomial model, its fit and its predictive properties were evaluated. The validated model was used for the quantification of 25 ointments, compounded by different retail pharmacists. The same standards and samples were used, both for development and validation of a regression model and for quantitative determination by HPLC - with sample preparation - as described for the related substances of salicylic acid in the Ph. Eur. IV. The quantification results obtained by the FT-Raman method corresponded with the HPLC results (p=0.22), provided that the particle size of salicylic acid in the standards is the same as in the analyzed samples. The non-destructive FT-Raman method is a reliable alternative for the destructive HPLC method, as it is faster and does not require sample pre-treatment procedures.

Calibration↗

PubMed2002

Assessment of the influence of media particle size on the biofiltration of odorous exhaust ventilation air from a piggery facility.

Two pilot scale biofiltration systems were constructed and installed at the University College Dublin Research Farm, Lyons Estate. Experimental units consisting of two pens in a 12 pen pig house were sealed off from other pens. Air from each pen was extracted and treated separately in two biofiltration systems. Wood chips larger than 20 mm were selected as the medium for biofiltration system 1, whereas chips of between 10 and 16 mm were used in biofiltration system 2. The moisture content of the media was maintained at 69+/-4% (w.w.b.) using a load cell method. The volumetric loading rates ranged from 769 to 1847 m3 [gas] m(-1) [medium] h(-1) over a 63-day experimental period. Both biofilters reduced odour between 88% and 95%. Ammonia removal efficiencies ranged from 64% to 92% and 69% to 93%, for biofiltration systems 1 and 2, respectively. Sulphur-containing compounds were reduced between 9-66%, and -147-51% across biofiltration systems 1 and 2. The pH of the biofilters' leachate remained between 6 and 8. Pressure drop for biofilter 2 was 16 Pa greater than that of biofilter I at the maximum volumetric loading rate of 1847 m3 [gas] m(-3) [medium] h(-1). It is recommended that a wood chip media particle size greater than 20 mm be used for large scale operation of a biofiltration system on intensive pig production facilities to reduce the development of anaerobic zones and to minimize pressure drop on the system fans.

Air Pollutants↗

PubMed1993

The effect of vacuum cleaners on the concentration and particle size distribution of airborne cat allergen.

BACKGROUND: Vacuum cleaners are essential for the removal of dust from the surface of carpets; however, they may also contribute to airborne dust both by leakage through the cleaner and disturbance of floor dust. METHODS: The present studies used established techniques for measuring airborne Fel d I to study the effects of vacuum cleaners on airborne cat allergen under laboratory conditions and in houses with cats. Nine different models were loaded with dust containing 50 mg Fel d I and run for 15 minutes in a laboratory room (volume approximately 18 m3). Leakage was expressed as the airborne concentration of allergen in nanograms per cubic meter. RESULTS: Cleaners incorporating a double-thickness dust bag either did not leak, that is, less than 0.4 ng Fel d I/m3 or had minor leakage approximately 5 ng/m3. Vacuum cleaners with single-thickness paper bags leaked more, that is, 15 to > 90 ng/m3 with the exception of the cleaner with an efficient outer bag. Detailed studies on a vacuum cleaner that leaked showed that placing dust in the bag, replacing the dust bag with a double-thickness bag, and placing an electrostatic filter over the exhaust reduced levels from greater than 90 ng/m3 to less than 2 ng/m3. Two water-filter vacuum cleaners each emitted cat allergen (up to > 100 ng/m3) with a mean of approximately 90% on particles less than 2.5 microns diameter. This emission could be almost completely controlled by taping electrostatic filter paper over the air outlet. CONCLUSIONS: In houses with cats, different models of vacuum cleaners could either reduce or increase total airborne allergen, and could also selectively increase certain particle sizes. These results suggest that cat allergen is a good model for studying the effectiveness of vacuum cleaners recommended to allergic patients.

Air Pollution, Indoor↗