Foam Plugs Research Articles

Atmospheric toxaphene in the high Arctic

The lack of information on seasonal variation of toxaphene (polychlorobornanes) in the arctic atmosphere has prompted a study in the Canadian north. Using high volume impactors with a 10 μm diameter size-selective inlet for particles and a collection cartridge consisting of a glass fiber filter followed by two polyurethane foam plugs, weekly samples were collected at Alert N.W.T. on a routine basis during the first six months of 1992. Samples were extracted and analysed by GC-ECD and confirmed by low and high resolution GC-MS. Total toxaphene concentrations ranged from < 1.6 to 27 pg m −3. They were lowest in January and rose to a peak in June at the end of the measurement period. GC-MS showed that in general, fewer chlorobornanes were observed in the PUF samples than in the technical toxaphene standard and the less volatile components of each homolog group (with longer GC retention times) were reduced in their relative proportions. Samples were dominated by hepta- and octachlorobornanes. Routine analysis by GC-ECD with occasional confirmatory analysis by higher resolution GC-MS techniques is a promising practical approach to atmospheric toxaphene measurements in remote areas.

Practical method for monitoring polychlorinated dibenzo- p-dioxins and polychlorinated dibenzofurans in the atmosphere

A practical method is described for monitoring tetra- to octachlorodibenzo- p-dioxins (T 4-O 8CDDs) and tetra- to octachlorodibenzofurans (T 4-O 8CDFs) in atmospheric samples at ground level. The substances in air were sampled on quartz fibre and polyurethane foam plugs by using a high-volume air sampler. The sample congeners were extracted with acetone, washed with sulphuric acid after transfer into a hexane layer, fractionated by silica gel and alumina column chromatography and subsequently analysed by gas chromatography—mass spectrometry. Thirty three peaks found for 47 congeners out of 49 T 4- O 8CDDs and 58 peaks found for 82 congeners out of 89 T 4-O 8CDFs could be monitored.

Multiyear Evaluation of the Effects of Nosema locustae (Microsporidia: Nosematidae) on Rangeland Grasshopper (Orthoptera: Acrididae) Population Density and Natural Biological Controls

A 3-yr evaluation of the biological control agent Nosema locustae Canning on grasshoppers was conducted on the National Wildlife Refuge at Maxwell, NM. Six O.1-ha plots were treated with the microsporidian in 1988; grasshopper densities were monitored in treatment and control plots through 1990. In 1988, there was a significant time-by-treatment interaction; grasshopper densities were significantly reduced for several weeks, with as much as 50% reduction by the end the season. Infections were highest 6 to 8 wk after treatment. Infection rates differed significantly across developmental stages and subfamilies. Melanoplinae were most heavily infected and suffered the greatest rate of mortality. Three additional orthopteran species were added to the host range of N. locustae . In the treated plots, in 1988, bird densities were significantly higher, and the parasitic wasp Scelio opacus (Provancher) was significantly more frequent in egg pods. Spores of N. loeustae were present in unhatched eggs and early instar nymphs, but no spores were observed on egg pods or foam plugs. In June of 1989, density of the treated population was similar to that of the controls, but from mid-July through mid-August the population density was significantly lower in the treated plots. Based on infection and demographic data, this second-year population suppression seems to have been the result of N.loeustae . In 1990, treated and control populations did not differ significantly, and both were reduced below the standard treatment threshold of 9.6 grasshoppers per square meter.

Design of a hearing test probe using active acoustic noise attenuation

Most hearing tests today are done in soundproof rooms. A method is proposed for conducting tests in a regular room while using a hearing test probe with active acoustic noise attenuation. The system consists of passive and active attenuation parts. The passive attenuation is achieved by a foam plug placed in the ear canal. The active attenuation is achieved by using two mini-microphones, a receiver and a DSP board. The first microphone is placed at the ear canal entrance and receives the acoustic noise. It then transfers the noise to the DSP board (with the TMS320, placed in a PC), which by using an adaptive algorithm transmits the antinoise signal to the receiver placed in the ear canal. The second microphone is placed near the receiver and produces the error signal to the adaptive process. The system was analyzed on a larger scale acoustic model and a 20- to 40-dB noise attenuation was achieved for tones up to 4 kHz (not including the plug passive attenuation). Theoretical analysis of the acoustic filter transfer function (from the outer microphone to the inner microphone) was done using computer simulation, and showed good agreement with measurement. Implementation of the system for broadband noise attenuation will be discussed. Preliminary results have shown that the characteristics and configuration of the acoustic probe and the DSP controller specifications have to be considered.

Effect of Starch Encapsulation and Temperature on Volatilization of Atrazine and Alachlor

AbstractVolatilization of agricultural chemicals is one process whereby chemicals may enter into parts of the environment where they were not intended. Starch encapsulation of pesticides has been proposed as a way of modifying pesticide behavior in the soil environment. This study was conducted to assess how starch encapsulation and temperature affect volatilization of atrazine [6‐chloro‐N‐ethyl‐N′‐(1‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine] and alachlor [2‐chloro‐N‐(2,6‐diethylphenyl)‐N‐(methoxymethyl)acetamide]. Volatilization was measured using agroecosystem chambers as model systems. Herbicides were applied at rates of 1.7 kg ha−1 for atrazine and 2.8 kg ha−1 for alachlor, as either a commercial formulation or a starch encapsulated formulation, to the surface of moist soils maintained at temperatures of 15, 25 and 35°C. Air was drawn through the chambers (2.5 m3 min−1) and herbicide in the vapor phase was trapped in polyurethane foam plugs. Volatilization of both herbicides increased as temperature increased. Volatilization of atrazine was less when applied as starch‐encapsulated formulation than the commercial formulation. After 35 d cumulative volatilization of atrazine ranged from &lt;1% of that applied as starch‐encapsulated formulation at 15°C, to 14% of that applied as the commercial formulation at 35°C. Cumulative volatilization of alachlor was greater when applied as starch‐encapsulated formulation than as the commercial formulation. After 35 d, cumulative volatilization of alachlor ranged from &gt;2% of that applied as either formulation at 15°C to 32% of that applied as starch encapsulated formulation at 35°C. Differences in volatilization behavior between these herbicides are likely to be due to differences in chemical properties of these herbicides.

環境水中のダイオキシン類の分析方法について 水試料からの抽出方法

This paper reviews analytical methods, especially those involving sample preconcentration, for the determination of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) in environmental water samples. In general, the analysis of these compounds is difficult, due to a combination of their generally low environmental levels and their physio-chemical properties e.g. low aqueous solubility and strong preference for particulate absorption. A large volume liquid liquid extraction and preconcentration system using an adsorbent resin e.g. XAD, C18, or a polyurethane foam plug, to extract PCDD/PCDFs from water samples has been reported. To separate the“truly dissolved” PCDD/PCDFs from that adsorbed by particulate matter in large volume of water, continuous centrifugation or filtration is available. Since there is little published data in this area, it is necessary to develop a reliable and easy to use preconcentration system in order to collect reliable data on PCDD/DF concentrations in natural water and so elucidate the behaviour of these chemicals in the environment.

Laboratory evaluation of polyurethane foam-granular adsorbent sandwich cartridges for collecting chlorophenols from air

Adsorbent traps containing 5-6g of Tenax-GC sandwiched between two 3-cm-thick polyurethane foam (PFU) plugs were used to collect six di- to tetrachlorophenols from 285-380m 3 of analyte-spiked air. Laboratory experiments were conducted by vaporizing known quantities of chlorophenols into a clean airstream for sampling by a General Metal Works PS-1 high-volume air sampler at 20 o C

Novel uses of cyanoacrylate adhesives — polycyanoacrylate foams

Cyanoacrylate polymer foams can be obtained by blending cyanoacrylate monomer with an appropriate solvent and a polymerization initiator. Foaming takes place in seconds at room temperature. Various monomers, solvents and initiators were tested and best performance compositions and ratios were determined. The resultant foams are lightweight and can occupy volume up to 30 times that of the original cyanoacrylate monomer. The onset time and temperature of foaming can be regulated in wide ranges. Odourless foaming compositions were obtained. The cyanoacrylate foam and foaming process can be used for a variety of medical applications such as broken-limb support, and blood vessel and Fallopian tube sealing. They are especially suitable for stoppage of fluid flow in industrial pipelines, e.g., gas mains. The foam plug can be collapsed at a later stage and fluid fluid restored.

Field worker exposure to selected insecticides applied to corn via center-pivot irrigation.

Field workers were monitored for dermal and respiratory exposure to chlorpyrifos (with and without crop oil), carbaryl, and permethrin at reentry intervals of 2, 4, 8, 24, and 48 h after application. Insecticides were applied to R3 stage corn through an overhead center-pivot irrigation system. Dermal exposure was measured by analyzing 18 gauze pads attached to the clothing of workers to represent human body regions. Hand exposure was determined using cotton gloves. Respiratory exposure was determined using portable air samplers equipped with polyurethane foam plugs to trap ambient insecticide residues. Gas liquid chromatography was used to quantify residues of chlorpyrifos and permethrin in gauze pads, gloves, and foam plugs. Carbaryl residues in pads, gloves, and foam plugs were analyzed using high-performance liquid chromatography. Highest dermal and respiratory exposures were found at the 2-h reentry interval. Exposures decreased as reentry interval increased. Dermal exposure was primarily confined to the hands. Residues detected by air samplers ranged from 0 to 0.03 micrograms/liter. Based on the estimated percentages of acute toxic dose (all less than 0.00038%), the risk of acute toxicity to workers at the intervals studied was low.

Exposure of applicators and residents to chlordane and heptachlor when used for subterranean termite control.

Research was conducted to assess dermal and respiratory exposure to applicators from chlordane and heptachlor used for subterranean termite control and exposure to residents of treated homes. Dermal exposure of 29 applicators was evaluated by using gauze pads attached to outer and inner clothing at selected body regions. Respiratory exposure of applicators was monitored with personnel-type air samplers worn during application periods. Air samplers were equipped with polyurethane foam plugs to trap airborne chlordane and heptachlor. Exposure of residents was measured by sampling ambient air of 19 homes treated with the termiticides. Electric air samplers equipped with foam plugs were used to monitor ambient air from the basement, the kitchen, and one bedroom at: 24 h prior to termiticide application, during application, and post-application at 24 h, 1 wk, and monthly for 6 mo. Applicator dermal exposure was estimated based on exposure rates to each body region. Respiratory exposure was estimated based on termiticide concentrations in the air and on the ventilation rate of a person doing light work. Residents' exposure was estimated based on the amount of termiticide present in ambient air. Results indicated that applicator exposure rates to chlordane and heptachlor were 2.54 and 1.88 micrograms/kg/h, respectively. Residents were exposed to less than 0.69 and 2.86 micrograms/m3 of chlordane and heptachlor, respectively. During this research, the application of termiticide containing chlordane and heptachlor posed minimal risk in terms of acute exposure to either the applicators or the residents of the treated homes.

Parallel sampling for dioxins using various sampling techniques at a swedish municipal solid waste incinerator

Parallel sampling was carried out in a Swedish municipal solid waste (MSW) incinerator, on two consecutive days, with five different sampling techniques. The samples were analysed for chlorinated dioxins (PCDDs) and chiorodibenzofurans (PCDFs) at two laboratories, one in Sweden and the other in Germany. Two different spiking protocols were used, both including pre-sampling or clean-up spikes from each homolog group of the tetra to octa CDDs and CDFs. Comparable results were obtained for all five sampling methods for the emission data and the recoveries for all pre-sampling spikes were above 50%. The agreement between the two laboratories was good. The different sampling methods resulted in very similar congener distributions (congener profiles) or isomer distributions (isomer patterns). However, the sampling techniques differ considerably in the distribution of PCDDs/PCDFs in various sampling compartments. The sampling techniques where large contribution of PCDDs and PCDFs could be found in the wash solvent may suffer from losses and/or cross-contamination problems unless the washing is carried out properly. The use of a cooled probe in combination with an adsorption (polyurethane foam plug) or absorption (ethoxyethanol) trap, where the main portion of the PCDDs and PCDFs were found in the condensate, is considered as a convenient and efficient sampling technique.

A Detached Shoot Technique To Evaluate the Reaction of Peanut Genotypes to Sclerotinia Minor1

Abstract The cut ends of 15-cm-long shoot tips from 15 peanut genotypes were immersed individually in 1 × 14 cm test tubes containing Hoagland's solution. Shoots were supported by foam plugs leaving about 12 cm extending above the foam plugs. All leaves were removed leaving about 1 cm of each petiole on the shoot. A 4-mm-mycelial plug of Sclerotinia minor, taken from the periphery of a 2-day old culture grown on potato dextrose agar containing 100 ug/ml streptomycin sulfate (SPDA), was placed between the stem and a petiole in the middle of the shoot. Tubes with shoots were then placed in a polyethylene enclosure on a greenhouse bench where the day and night temperature were 29 ± 2C and 25 ± 2C, respectively. Relative humidity (RH) was maintained at 95 to 100% by lining the bottom of the enclosure with wet burlap. Lesions appeared on shoot tips 3 days after inoculation, and their length was measured at various times. Genotypes with the least percent of symptomatic stems also had the lowest rates of lesion expansion. Two weeks after inoculation, tubes were drained, and shoots remained in the chamber at about 60–70% RH to allow sclerotial production. Sclerotia from each shoot were removed, counted, and their viability determined by germination on SPDA at 25 ± 2C in darkness. This method was effective in differentiating the reaction of peanut genotypes to infection by S. minor.

Parallel Sampling for Dioxins Using Various Sampling Techniques At a Swedish Municipal Solid Waste Incinerator

Parallel sampling was carried out in a Swedish municipal solid waste (MSW) incinerator, on two consecutive days, with five different sampling techniques. The samples were analysed for chlorinated dioxins (PCDDs) and chlorodibenzofurans (PCDFS) at two laboratories, one in Sweden and the other in Germany. Two different spiking protocols were used, both including pre-sampling or clean-up spikes from each homolog group of the tetra to octa CDDs and CDFs. Comparable results were obtained for all five sampling methods for the emission data and the recoveries for all pre-sampling spikes were above 50%. The agreement between the two laboratories was good. The different sampling methods resulted in very similar congener distributions (congener profiles) or isomer distributions (isomer patterns). However, the sampling techniques differ considerably in the distribution of PCDDs/PCDFs in various sampling compartments, The sampling techniques where large contribution of PCDDs and PCDFs could be found in the wash solvent may suffer from losses and/or cross-contamination problems unless the washing is carried out properly. The use of a cooled probe in combination with an adsorption (polyurethane foam plug) or absorption (ethoxyethanol) trap, where the main portion of the PCDDs and PCDFs were found in the condensate, is considered as a convenient and efficient sampling technique.

A Controlled Investigation of In-Field Attenuation Performance of Selected Insert, Earmuff, and Canal Cap Hearing Protectors

A field study assessed the actual spectral noise attenuation achieved by 40 industrial workers wearing four different hearing protection devices (HPDs) while on the job. The effect of two different HPD fitting procedures (subject fit vs. trained fit) on attenuation performance over two three-week periods of protector use was determined. Subjects were retrieved from their workplaces without prior knowledge of when they were to be tested and were not permitted to readjust the fit of their HPDs. Attenuation data were then collected using psychophysical procedures testing real ear attenuation at threshold. Statistical analyses indicated that the earplugs' attenuation significantly improved when training for proper fitting was used, whereas the earmuff and the ear canal cap were relatively insensitive to the training effect. The training was most effective for a slow-recovery foam plug over the three-week period. Results confirmed that laboratory protocols designed to simulate workplace influences on attenuation may not be relied on to yield reasonable estimates of field protection performance of HPDs, particularly for earplugs; however, the laboratory results were much better predictors of field protection for the earmuff. This study also demonstrated that the labeled manufacturers' noise reduction ratings (NRRs) substantially overestimated the actual field attenuation performance.

Real-Ear Attenuation under Laboratory and Industrial Test Conditions as Provided by Selected Hearing Protectors

To determine if controlled laboratory measurement procedures could yield realistic estimates of actual hearing protector performance achieved in the workplace, laboratory and field studies were performed using a like set of test protocols and hearing protection devices (HPDs). The laboratory experiment, using 40 naive subjects, investigated the effects of HPD wearing time, activity movement, and 2 fitting conditions (naive subject-fit vs. trained subject-fit), on spectral attenuation afforded by a slow-recovery foam earplug, premolded plug, foam cushion earmuff, and the muff worn over the foam plug. The field study, using 40 noise-exposed industrial workers, determined the protection obtained over 6 weeks of HPD use in 5 industrial workplaces. Statistical contrasts of mean data across frequency showed that the laboratory post-activity task (i.e., worst case) attenuation results overestimated the field attenuation by 8.3 dB (under the subject-fit) and 5.7 dB (under the trained-fit) for the user-molded foam plug, and by 10 dB and 6 dB, respectively, for the premolded plug. The laboratory results provided a much better prediction of field protection for the earmuff than for the plugs. Because of the discrepancies in prediction accuracy for different types of HPDs, schemes which have been proposed to “derate” the manufacturers' attenuation data by a constant factor across protectors are not justifiable.

Detoxification and Evaluation of Foam Supports for Aeroponically Grown Soybean

Polyurethane‐based foam plugs used as supports for aeroponically grown soybean plants [Glycine mu (L.) Merr.] contain a phytotoxic compound. Plugs were detoxified after soaking in 1.0 M NaOH for 1 h and then in 950 mL L−1 ethanol for 12 h. Five additional foam materials were evaluated as substitutes for polyurethane foam plugs. Four of the five foams tested (reticulated ether‐based foam, etbafoam, Dowstrand foam, and L/C 200 foam) were nontoxic to soybean plants. Of these, reticulated ether‐based foam (39.4 or 31.4 pores cm−l) had physical properties similar to polyurethane foam and is recommended as a substitute for this material.

Hearing protector attenuation performance under different simulated work and fitting conditions

Four hearing protectors—a foam‐cushion earmuff, foam and triple‐flanged polymer earplugs, and an earmuff over foam earplug combination—were evaluated to determine the effects of wearing time, movement activity, and fitting procedure on spectral attenuation. Using a psychophysical real‐ear‐attenuation‐at‐threshold measurement procedure (as per ANSI S12.6‐1984), attenuation data were collected from 40 naive subjects before, during, and after the activity movement tasks, which induced highly kinematic subject movements. Loss in attenuation over the 2‐h wearing period was up to 6 dB for all devices except the foam earplug, and all protectors except the earmuff significantly improved protection (from 4 to 14 dB) at 1000 Hz and below due to trained fitting. The foam plug benefited more than other devices from the training for proper fitting but was resilient to subject movement. [Work supported by NIOSH‐NIH.]

Attenuation Performance of Four Hearing Protectors under Dynamic Movement and Different User Fitting Conditions

An experiment was conducted to determine the effects of movement activities and alternative fitting procedures on protection levels afforded by four hearing protection devices (HPDs). Psychophysical attenuation measurements at nine one-third-octave bands from 125 to 8000 Hz were obtained prior to, during, and following a 2-hr wearing stint that included periods of either highly kinematic but controlled work activity or vigorous temporomandibular movement. The 40 subjects, who were nonusers of HPDs, initially fit the protectors according to either the instructions on the package (i.e., subject fit) or after receiving interactive training on proper fit (i.e., trained fit). Thereafter no further protector adjustments were allowed during the wearing period. The subject-fit condition resulted in significantly lower protection levels, from 4 to 14 dB, at 1000 Hz and below for a premolded polymer earplug, a user-molded foam earplug, and a double protector consisting of a muff over the foam plug. The muff alone was significantly more resilient to fitting effects on attenuation than were the plugs. Movement activity caused up to a 6-dB significant reduction in frequency-specific attenuation over time for the premolded plug, muff, and muff-plug combination. The compliant foam earplug was largely resistant to either type of movement effect but did benefit more than the other devices from use of the trained-fit procedure. Implications of the results for hearing protector testing protocol, device selection, and user training are discussed.

The biocompatibility of compressed collagen foam plugs

The tissue reaction to reexpanded, purified bovine collagen sponge placed percutaneously into the lung, pleural space, liver, kidney, and muscle was studied in dogs and rabbits. In addition, the biocompatibility and radiopacity of tantalum-treated collagen foam plugs was examined. No adverse effects were found. We believe that collagen plugs may be of use in occluding needle tracts from biopsy sites to prevent complications such as bleeding or pneumothoraces.

Studies on sampling methods for PCDDs and PCDFs in stack emission

Polychlorinated dibenzo- p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in stack emission exist both as vapor and sorbed onto the surface of particles. The partition between the two phases is of a dynamic nature and changes rapidly with temperature. When monitoring stack emissions, a sampling method must be used that efficiently collects both phases as well as any condensation aerosol formed in the sampling train. In this study, the two sampling methods used in Sweden, the cooled probe polyurethane foam plug (PUFP) sampling train and the sampling train recommended by the Swedish Environmental Protection Board has been tested for particle collection ability. The results show that an aerosol filter has to be introduced after the condensor in order to collect particle bound PCDDs and PCDFs efficiently.