Absolute Filter Research Articles

In vitro comparison of heliox and oxygen in aerosol delivery using pediatric high flow nasal cannula

Drug administration via high flow nasal cannula (HFNC) has been described in pediatrics but the amount of albuterol delivery with an HFNC is not known. The purpose of this study is to quantify aerosol delivery with heliox and oxygen (O(2)) in a model of pediatric ventilation. A vibrating mesh nebulizer (Aeroneb Solo, Aerogen) was placed on the inspiratory inlet of a heated humidifier and heated wire circuit attached to a pediatric nasal cannula (Optiflow, Fisher & Paykel). Breathing parameters were tidal volume (V(t)) 100 ml, respiratory rate (RR) 20/min, and I-time of 1 sec. Albuterol sulfate (2.5 mg/3 ml) was administered through a pediatric HFNC with O(2) (100%) and heliox (80/20% mixture). A total of 12 runs, using O(2) and heliox were conducted at 3 and 6 L/min (n = 3). Drug was collected on an absolute filter, eluted and measured using spectrophotometry. The percent inhaled dose (mean ± SD) was similar with heliox and O(2) at 3 L/min (11.41 ± 1.54 and 10.65 ± 0.51, respectively; P = 0.465). However at 6 L/min drug deposition was ≥ 2-fold greater with heliox (5.42 ± 0.54) than O(2) (1.95 ± 0.50; P = 0.01). Using a pediatric model of HFNC, reducing delivered flow from 6 to 3 L/min increased inhaled albuterol delivery ≥ 2-fold but eliminated the increase in inhaled drug efficiency associated with heliox.

Effect of vaccination of pigs against experimental infection with high and low virulence Mycoplasma hyopneumoniae strains

This study investigated the infection pattern and lung lesion development in pigs caused by a low and highly virulent Mycoplasma hyopneumoniae strain at 4 and 8 weeks (w) post infection (PI). It also determined the efficacy of a commercial inactivated whole-cell vaccine against infection with each one of these M. hyopneumoniae strains. Ninety piglets free of M. hyopneumoniae were selected, and 40 of them were randomly vaccinated during their first week of life. At weaning, all piglets were allocated to 10 different groups and housed in pens with absolute filters. At 4 weeks of age, pigs were inoculated intratracheally with either a highly virulent M. hyopneumoniae strain, a low virulent strain or with sterile culture medium. Half of all animals were euthanized at 4w PI, while the remaining half was euthanized at 8w PI. Coughing was assessed daily, and lung lesions, immunofluorescence (IF), bacteriological analysis and nested PCR were assessed after necropsy. It was demonstrated that contrary to the highly virulent strain, the low virulent strain required more than 4 weeks PI (commonly accepted as the standard infection model) to reach maximum clinical symptoms. Vaccination significantly reduced clinical symptoms, macroscopic and microscopic lung lesions in pigs infected with the highly virulent strain. This effect was more pronounced at 4 than at 8 weeks PI. Protective efficacy was also observed in pigs infected with the low virulent strain, but the effect was less pronounced than on the highly virulent strain.

Influence of TiO2Additive on Vaporization of Potassium during Straw Combustion

In this work, the influence of TiO2 on the vaporization of K during combustion of straw under fixed bed condition was investigated experimentally. Controlled combustion experiments with a varied amount of TiO2 in straw pellets were performed in an 8 kW pellet burner together with sampling of particles (impactor and absolute filter), analysis of the flue gas composition (Fourier transform infrared, FTIR), and chemical analyses of the collected particles and bottom ash (inductively coupled plasma-atomic emission spectroscopy (ICP-AES), scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS), and X-ray diffraction (XRD)). The experimental results showed that the vaporization of K from the fuel bed was significantly reduced when TiO2 was used as an additive. The vaporization of K was reduced by ∼40−50% for an optimal amount of TiO2 additive. The optimal added TiO2 for the straw used in this work corresponds to a Ti/K (wt) ratio between ∼0.6−1.0. If more TiO2 was added to the fuel, the release of K to the gas phase was not further reduced and unreacted TiO2 was found in the bottom ash.

Remediation of asbestos containing materials by Joule heating vitrification performed in a pre-pilot apparatus

A remediation method for asbestos containing materials based on vitrification by Joule heating is presented. Crystal phase transformations of several asbestos minerals were investigated. The vitrification technology on a pre-pilot scale was applied to cement-asbestos pipes containing simultaneously chrysotile and crocidolite. The progressive heating up to 1600 °C led to the complete melting of fibrous minerals and the rapid cooling of the melt formed a monolithic glass. Mineralogical (XRD) and morphological (SEM) analysis showed absence of crystalline phases within the glass. The external part of the Joule heated volume was not melted but lacked asbestos because of an irreversible thermal conversion of asbestos and silicate minerals into high temperature silicates (enstatite and diopside). An absolute filter integrated in the gas effluent treatment system avoided the release of asbestos fibres during the vitrification process. This process assured the complete remediation of asbestos containing materials and its scaling up to the field application could be a suitable industrial treatment of tons of material.

Proving the possibility of physical removal of particulate matter with the SJAC-technology

Particulate matter emissions from shipping affect air quality in port areas. Physical removal of par ticulate matter is difficult due to the small size of particles. In this ar ticle the so-called Steam Jet Aerosol Collector (SJAC) is introduced; a novel technique to enlarge particulate matter, facilitating its physical removal. Results are presented from experiments conducted on a pilot-scale test facility.The SJAC-technology shows potential in combination with a cyclone having a maximum number removal efficiency of 33%, as measured with an SMPS and a maximum mass removal efficiency of 24%, as measured with an absolute filter at 110°C (383K). Further system development is however necessary.

Treatment of Seawater With Cartridge Filtration–A Field Trial

Summary In offshore operations, seawater is often injected to maintain reservoir pressure for enhanced oil recovery. A sulfate-reducing membrane (SRM) is typically used to reduce the sulfate content in the seawater from 2900 mg/L to less than 50 mg/L to prevent souring of the reservoir by sulfate reducing bacteria and formation of barium and strontium sulfate scale when seawater is mixed with formation water. A two-cartridge in-series filtration pilot unit installed on a deepwater platform in the Gulf of Mexico (GOM) has demonstrated that cartridge filtration can be used upstream of the SRM to pretreat seawater to meet the SRM feed seawater specification of a silt density index (SDI) <5 and a nephelometric turbility unit (NTU) < 1. Scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) was used to determine the composition of the material deposited on the surface of a used cartridge filter. From the SEM/EDS results, it was concluded that the filters were blocked predominantly by coccoliths (calcium compounds), diatoms (silicon compounds), iron oxide corrosion products, and broken, crushed marine debris, that formed a fine-grained membrane cake on the filters. It was found that a two-filter in-series configuration is a better seawater filtration system than using a single filter if seawater with an SDI <3.5 is required. With the installation of a 50-micron nominal filter upstream of a 10-micron absolute filter, the service life of a 10-micron filter was increased by 20 times.

Microbiological surveillance of hospital ventilation systems in departments at high risk of nosocomial infections.

The air in hospital wards with patients at high risk (Surgeries, Intensive Care Units and Bone Marrow Transplant Centers) has been surveyed less than the one in Operating Rooms. Therefore in this study we considered useful to verify the microbic contamination of the air of those wards evaluating the consistency of ventilation systems in relation also to the presence and location of HEPA absolute filters. Seven departments of Genoese San Martino Hospital at high risk of infection were taken into account. In there, environmental investigations have been performed by air samplings and by analyzing bacterial and fungal growth on plates after an incubation period. Almost 60% of all samples taken in wards yielded a positive result and the average values of bacterial and aspergillar charges measured at air flow emission openings decisively exceed the ones considered standard in operating rooms. Still, the average values of airborne bacterial charges were significantly higher in those wards equipped with central filters (p < 0.001), while as far as the aspergillar charge is concerned, no statistically relevant differences were noticed. In wards with ventilation system, the bacterial charge value raises from the emission grids to the middle of the room and to the aspiration grids, while the ward not equipped with a ventilation system presents in the middle of the room an average bacterial charge 2 to 10 times higher than the one in other wards. The average values regarding bacterial and aspergillar charges resulted quite high in all the departments surveyed. Nevertheless, if we take into account ventilation systems equipped with absolute filters HEPA located centrally or peripherally, it can be outlined that the air quality from the point of view of both microbic and aspergillar contamination turns out to be decisively better in systems with peripheral filters. Moreover, a compared analysis of the three Hematology wards allows us to infer that the presence of artificial ventilation systems can lower the bacterial and fungal compared with a ward with natural ventilation.

Aerosol Profile Extracted from Spacers as a Determinant of Actual Dose

We propose a novel method to evaluate the efficacy of a pressurized metered dose inhaler (pMDI) in combination with a spacer, by not only considering the total dose extractable from the spacer but also the dependence of dose on the volume available for aerosol inhalation. We studied volume-dependence of aerosol concentration during extraction from two commonly used plastic spacers (150 ml AerochamberPlus; 750 ml Volumatic) after a single puff of a 100 microg salbutamol pMDI (HFA-Ventolin), using laser photometric measurements. After a delay of is in each spacer, the aerosol peak dose for AerochamberPlus was 2-fold that for Volumatic (p < 0.001), with the peak appearing well within the first 0.5 L even for the largest spacer. The opposite dose relationship is reached when considering total cumulative dose, which was 2-fold higher for Volumatic than for AerochamberPlus (p < 0.001); >95% of total cumulative dose was extracted well within 3 L for the largest spacer. The 2-fold cumulative dose relationship was confirmed by chemical assay on an absolute filter [AerochamberPlus: 21.4+/-3.2 (SD) microg; Volumatic: 43.8+/-9.1 (SD) microg]. Actual aerosol dose available to patients during inhalation via spacers can only be done on the basis of a quantification of aerosol peak dose and cumulative dose as a function of extracted volume.

Image reconstruction techniques using projection data from transmission method

This paper gives a brief description of a filter back projection (FBP) and Algebraic Reconstruction techniques (ART), which are used for reconstruction of projected data obtained from transmission measurements. Both techniques are tested by reconstructing a simulated object, showing that the FBP technique yields images with better resolution and higher contrast, thus resulting in more accurate information than obtained by ART. Experimental data has been obtained for unheated and heated ordinary and heavy concrete samples by transmission measurements using a thermal neutron beam emitted from the spallation neutron source SINQ at PSI, Switzerland. The data are used to reconstruct the images of the examined samples using the FBP technique with different filter functions, including the Shepp Logan filter function produces images of higher contract, more smoothing and slightly better resolution than those obtained using the absolute filter function. Based on these images the samples were investigated for water content, cracks, homogeneity, etc.

Long-term temporal stability of the National Institute of Standards and Technology spectral irradiance scale determined with absolute filter radiometers.

The temporal stability of the National Institute of Standards and Technology (NIST) spectral irradiance scale as measured with broadband filter radiometers calibrated for absolute spectral irradiance responsivity is described. The working standard free-electron laser (FEL) lamps and the check standard FEL lamps have been monitored with radiometers in the ultraviolet and the visible wavelength regions. The measurements made with these two radiometers reveal that the NIST spectral irradiance scale as compared with an absolute thermodynamic scale has not changed by more than 1.5% in the visible from 1993 to 1999. Similar measurements in the ultraviolet reveal that the corresponding change is less than 1.5% from 1995 to 1999. Furthermore, a check of the spectral irradiance scale by six different filter radiometers calibrated for absolute spectral irradiance responsivity based on the high-accuracy cryogenic radiometer shows that the agreement between the present scale and the detector-based scale is better than 1.3% throughout the visible to the near-infrared wavelength region. These results validate the assigned spectral irradiance of the widely disseminated NIST or NIST-traceable standard sources.

Adaptation of Planetary Atmospheres Modeling Methods for Analysis of Coma Dust Optical Properties in Comet C/1995 O1 (Hale–Bopp): I

Incipient attempts to apply a single-scattering polarized radiative transfer code along with planetary atmospheres spectrum synthesis procedures to photometric analyses of coma dust optical properties in Comet Hale–Bopp have lead to results which are consistent with other independent derivations of dust physical properties like particle composition, size, number densities, and ejection speeds. In the present optical modeling, preperihelion absolute filter photometry of Hale–Bopp's inner coma is compared with synthesized spectra of candidate haze particles. The calculations have demonstrated that the reflectances of crystalline olivine aerosols with effective radii of about 0.15 μm are compatible with the comet's λ ≈ 0.4–0.7 μm spectrum. A good fit to Hale–Bopp's continuum spectrum is achieved with a high preponderance of these bright, submicrometer-sized particles.

In Vitro Determination of Inhaled Mass and Particle Distribution for Budesonide Nebulizing Suspension

ABSTRACT Nebulized delivery of aerosols to the lung is a complex process dependent on the device, the drug preparation, the patient's breathing pattern and other factors. It is difficult to predict drug delivery in advance and most delivery systems are studied empirically on the bench. To standardize the delivery of aerosolized budesonide suspension, we measured the quantity of drug delivered to the patient mouthpiece using a piston pump as a model of patient breathing and absolute filters. The mass of aerosol at the mouthpiece (the inhaled mass) was determined by high-pressure liquid chromatography (HPLC). The aerodynamic properties of the nebulized budesonide particles were determined by cascade impaction and HPLC. Because the drug is used to treat children, the bench model was based on a pediatric breathing pattern, that is, a tidal volume of 200 mL, a breathing frequency of 25 per minute, and a duty cycle of 0.5. Twenty-seven nebulizer/compressor combinations were studied. Inhaled mass varied over...

Aerosol Delivery During Continuous Nebulization

Continuous administration of aerosolized beta 2-agonists has been suggested as an effective treatment for severe reversible airways disease. To facilitate continuous therapy and avoid a feed system for small-volume nebulizers (SVNs), a large-volume medication nebulizer (Vortran HEART) was developed. The goal of this study was to determine actual drug delivery of the HEART and conventional SVNs for both adult and pediatric breathing patterns. Output studies were conducted on comparable samples of CIS-US AeroTech II and Hospitak PowerMist SVNs and Vortran HEART large-volume continuous nebulizers. To duplicate clinical aerosol delivery via an aerosol mask, drug particles were inhaled through the mouth of a model of a human face for two test breathing patterns (adult = tidal volume (Vt) of 500 mL, 20 breaths/min, duty cycle of 40%; pediatric = VT of 100 mL, 35 breaths/min, duty cycle of 40%), generated by a ventilator. Radiolabeled particles of saline solution, confirmed to behave identically to albuterol, were collected on absolute filters at the mouth of the face to measure the actual mass of albuterol particles delivered to the airway opening. The AeroTech II and PowerMist SVNs delivered 5.14 and 3.74 mg/h, respectively, for the adult breathing pattern and 2.97 and 2.48 mg/h, respectively, for the pediatric breathing pattern. Drug delivery rates of the HEART were a function of drug concentration and ranged from 0.87 to 3.48 mg/h for the adult breathing pattern. For the pediatric breathing pattern, drug delivery rate was a function of drug concentration and inspired minute ventilation and ranged from 0.41 to 1.83 mg/h. Our data demonstrate that drug delivery to the patient, expressed as inhaled mass over time, is similar for continuous nebulization (HEART system) and intermittently filled SVNs. In addition, for all nebulizers, the influence of the pediatric breathing pattern needs to be considered. Continuous nebulization permits the redistribution of health-care personnel and may reduce the costs of therapy.

Cross Absolute Filter for Removing Speckle Noise from Interference Patterns

A new algorithm for speckle noise removal from interference patterns is proposed. The method, called cross absolute filter (CAF), is especially well suited for noisy interferograms with phase error pixels. Extensive computer simulations performed on both digitally generated fringes and experimental data show that CAF performs better than classical median-type filters, preserving more subtle details.

Melt-blown cartridge technology

Historically, thermally bonded or melt-blown depth cartridges were defined as nominal filters, and the term ‘absolute filter’ was reserved for surface cartridge types. With the arrival of improved manufacturing techniques, however, absolute ratings can now be achieved with depth filters. In this article, Chris Faulder, European product manager for Parker Hannifin's Fulflo Division, explains the changes in definition, and outlines the benefits of both types of filter for the chemical process industry.

Pulmonary deposition of aerosolised pentamidine using a new nebuliser: efficiency measurements in vitro and in vivo

The therapeutic efficacy of nebulised pentamidine in the prophylaxis of Pneumocystis carinii pneumonia (PCP) depends on the absolute pulmonary deposition of the drug. We studied the performance of a new nebuliser (Pentasave) by comparison both in vitro and in vivo with a standard nebuliser (Respirgard II). In vitro, deposition of pentamidine labelled with technetium-99m human serum albumin was measured indirectly by capturing inhaled particles on an absolute filter and measuring radioactivity with a gamma camera. The nebulisers were initially assessed with a pentamidine dose of 100 mg in 5 ml at 44 psi and an air flow of 10 l/min for Respirgard II and 16 l/min for Pentasave. Nebuliser output, expressed as the percentage of the initial nebuliser radioactivity captured by the inhalation filter, was 15% +/- 2% (mean +/- SD) for Respirgard II, and significantly increased to 23% +/- 3% for an initial version and to 33% +/- 2% for the final version of Pentasave. Measurements with a gamma camera in a group of ten patients with human immunodeficiency virus infection were made in vivo. The results revealed that pulmonary drug distributions are good using both Respirgard II and Pentasave. The literature reports that once-monthly pulmonary deposition of 9 mg pentamidine seems enough to produce prophylactic effects against Pneumocystis carinii. We measured pulmonary pentamidine deposition of 20.22 +/- 4.31 mg (mean +/- SD) using Respirgard II (with 300 mg in 5 ml) and of 16.00 +/- 7.18 mg using Pentasave (with 150 mg in 6 ml). These findings show that the therapeutic dose of pentamidine (9 mg) was widely exceeded with both nebulisers. Further investigations might demonstrate that about 200 mg and 125 mg pentamidine for Respirgard II and Pentasave, respectively, will achieve a pulmonary deposition of therapeutic dose, allowing significant savings in terms of drug and expense.

Adaptation of a glow discharge mass spectrometer in a glove-box for the analysis of nuclear materials

A VG9000 glow discharge mass spectrometer has been modified for the direct analysis of solid nuclear samples within a glove-box environment. Because containment is needed for the analysis of this kind of material, the glove-box encloses all parts of the instrument that come into contact with the sample, namely the ion source chamber, sample interlock and associated pumping system. External modifications eliminate outside contamination by the fitting of absolute filters on all source supplies. Internally, the design of the ion source has been altered to minimize the number of operations performed inside the glove-box thereby simplifing operation and routine maintenance. These modifications retain the ion extraction and focusing properties of the instrument. The data presented show that there is no compromise in the analytical performance of the instrument when placed in the glove-box. Data representative of nuclear materials is also shown.

A frequency reference photonic integrated circuit for WDM with low polarization dependence

A photonic circuit implementing ten frequency reference filters for narrow-channel wavelength division multiplexing (WDM) has been fabricated. A diluted multiquantum-well waveguide structure is shown to yield a very low TE/TM polarization dependence of 1 AA, as well as improved absolute frequency control and reproducibility. A standard deviation in absolute filter wavelength of 3.33 AA is measured on a random set of devices from a 2-in wafer. The ten channels are evenly spaced by 7.2 AA. Such filters can be used to lock tunable lasers to a set of reference frequencies for WDM applications. The demonstrated diluted multiquantum-well waveguide structure with low birefringence and improved absolute wavelength control could potentially be used in other WDM integrated circuits requiring tight wavelength tolerance and polarization insensitivity. >

Equipment

Pall has expanded its Profile range of absolute rated depth filters with the introduction of the Profile Star filter.

Aerosol Delivery During Mechanical Ventilation: A Predictive In-Vitro Lung Model

to compare aerosol delivery from a standard (Bennett) nebulizer, a submicronic (Ultravent) nebulizer, a metered dose inhaler (MDI) plus small holding chamber, and an MDI plus large holding chamber, using a laboratory model simulating a mechanically ventilated patient. saline solution (for the nebulizers) and fenoterol MDI's were radiolabelled and the model set up. After 15 minutes nebulization, or after single puffs from MDI, 1 minute static images were taken of the filter (representing the 'lungs'). Radioactivity in the filter was then counted and expressed as a percentage of the initial radioactivity in the nebulizer, or per puff from MDI. Counts were also made of the endotracheal tube (ETT) and chamber in a subgroup of studies. radioactivity delivered to the filter from MDI plus large chamber (30.3 ± 7.4%) (mean ± 1SD) and MDI plus small chamber (27.7 ± 5.1%) was significantly greater than from Bennett (4.6 ± 2.1%) and Ultravent (1.3 ± 0.4%) nebulizers. In experiments using MDI plus small chamber there was 52.1 ± 5.8% deposition into the chamber, and 5.9 ± 2.0% deposition onto the ETT. In experiments using Bennett nebulizer there was 2.3 ± 1.0% deposition to the ETT. Comparison of 'lung' inhalation from Bennett nebulizer between experiments with and without humidity was 4.6 ± 2.1% and 7.8 ± 0.5% respectively (p = 0.002). 1) Delivery of aerosol to the model lung is greater using MDI plus chamber than using nebulizer. 2) There is no significant difference in activity delivered to the filter between MDI using either size of chamber. 3) Much of the initial aerosol remains in the nebulizer or chamber, and less in the ETT. 5) Warming and humidification of the inspired gas reduces the amount of available aerosol towards the level of lung deposition seen in clinical studies. 4) Deposition to filter of both 99mTechnetium sulphur colloid (99mTc-SC) and 99mTechnetium pertechnetate (99mTcO4) from a nebulized saline solution was reduced by approximately 50% when fenoterol was added to the solution. As this difference was similar for both compounds, proportional differences of deposition between the devices tested here remain unchanged. 6) Lung models such as the one described in this study receive approximately 3 times as much on the filter as deposits in the lungs In human studies, for all devices. This is likely due in part to impaction of all the aerosol on the absolute filter in the model, but exhalation of part of the inhaled aerosol in human studies. 7) Further efforts must be made to develop models that more closely mimic human physiology in mechanically ventilated patients.