Μm Standard Deviation Research Articles

Biomass burning smoke aerosol properties measured during Fire Laboratory at Missoula Experiments (FLAME)

During the Fire Laboratory at Missoula Experiments (FLAME), we studied the physical, chemical, and optical properties of biomass burning smoke from the laboratory combustion of various wildland fuels. A good understanding of these properties is important in determining the radiative effects of biomass burning aerosols, with impacts on both local and regional visibility and global climate. We measured aerosol size distributions with two instruments: a differential mobility particle sizer (DMPS) and an optical particle counter (OPC). Volume size distributions from different burns varied from monomodal to multimodal, with geometric mean diameters ranging from 0.20–0.57 μm and geometric standard deviations ranging from 1.68–2.97. By reconciling the differences between the two sizing instruments, we estimated aerosol effective refractive indices with values ranging from 1.41 to 1.61. We reconstructed aerosol chemical composition for each burn using data from filters collected and analyzed with the Interagency Monitoring of Protected Visual Environments (IMPROVE) samplers and protocols. Aerosols were generally comprised of carbon with organic species accounting for the largest mass fraction in most cases. We used composition data to calculate aerosol density, which ranged from 1.22–1.92 g cm−3, and real and imaginary refractive indices, which had ranges of 1.55–1.80 and 0.01–0.50 respectively. Aerosol physical, chemical, and optical characterizations were combined to calculate dry mass scattering (MSE) and absorption (MAE) efficiencies at 532 nm. These parameters had values between 1.6–5.7 m2 g−1 and 0.04–0.94 m2 g−1.

Design and evaluation of single nozzle with a non-conductive tip for reducing applied voltage and pattern width in electrohydrodynamic jet printing (EHDP)

We investigated the effect of a non-conductive tip inserted into a capillary nozzle (inner diameter of 860 µm) on jet formation and pattern width in electrohydrodynamic jet printing. Simulated and experimental results showed that the non-conductive tip stabilized the jet, and reduced the effective nozzle diameter and the onset voltage needed for the cone-jet mode, by eliminating the backflow near the apex of the liquid cone while a tiny backflow away from the apex of the liquid cone still remained. Silver nanocolloid patterns with an average width of 18.5 µm (standard deviation: 1.5 µm) were obtained with an applied voltage of 2.7 kV, a flow rate of 3 µl min−1 and a stage velocity of 200 mm s−1.

Spawning Induction, Fecundity Estimation, and Larval Culture ofSpondylus calcifer(Carpenter, 1857) (Bivalvia: Spondylidae)

ABSTRACT In this study we describe spawning induction, fecundity estimation, and the early life history of the rock scallop Spondylus calcifer under laboratory conditions. We collected adults of S. calcifer from a natural stock in the Gulf of California, Mexico (28°37′N, 112°15′W). We induced spawning by means of thermal shocks (10°C magnitude) and estimated species fecundity as a function of size. We evaluated the effects on growth rate and final survival of larvae reared with 3 dietary treatments: (1) 30 cells/µL, (2) 50 cells/µL, and (3) 75 cells/µL. We reared larvae in 15-L containers at a density of 3 larvae/mL at 30°C, and renewed 100% of the water culture every 48 h. The diet comprised a combination (1:1) of Isochrysis galbana (clone T-ISO) and Chaetoceros calcitrans (clone C-CAL). Both females and males responded positively to thermal shock induction. Mean size of oocytes was 56.0 ± 4.2 µm (standard deviation; n = 30). Mean number of oocytes spawned was 48.9 × 106 ± 13.2 × 106 with the smallest fe...

Repeatability of Retinal Thickness Measurements Between Spectral-Domain and Time-Domain Optical Coherence Tomography Images in Macular Disease

To evaluate and compare the intra-session repeatability of retinal thickness measurements from the Topcon 3D OCT 1000 (Topcon Medical Systems; Paramus, NJ), a spectral-domain optical coherence tomography (SD-OCT) system, with the Stratus (Carl Zeiss Meditec, Inc., Dublin, CA), a time-domain OCT (TD-OCT) system, in eyes with retinal diseases. Repeated scans with both SD-OCT and TD-OCT were taken. Thickness measurements from high-quality scans were used to assess repeatability and compare measurements between the two instruments. Paired scans from 127 eyes were evaluated, of which 63 pairs were of high quality. Coefficients of repeatability and variation for the central subfield were 20.1 μm (2.6%) with SD-OCT and 27.4 μm (4%) with TD-OCT (P = .38). The mean difference in central subfield thickness between the two instruments was 24.5 μm (standard deviation = 20.9). Repeatability of retinal thickness measurements with the Topcon 3D OCT 1000 is comparable to the Stratus. The measurements of the two machines differ significantly and cannot be used interchangeably.

Comparison of central corneal thickness measurements with the Galilei dual Scheimpflug analyzer and ultrasound pachymetry

Purpose:To compare corneal pachymetry assessment by the Galilei dual Scheimpflug analyzer with that done by ultrasound (US) pachymetry.Materials and Methods:Forty six patients (92 eyes) were subjected to corneal pachymetry assessment by Galilei dual Scheimpflug analyzer and US. All the readings were taken by a single operator. Intraoperator repeatability for the Galilei was assessed by taking 10 readings in one eye each of 10 patients. To study the interoperator reproducibility for the Galilei, two observers took a single reading in both the eyes of 25 patients.Results:The mean central corneal thickness (CCT) measured by US was 541.83 ± 30.56 μm standard deviation (SD) and that measured by Galilei was 541.27 ± 30.07 μm (SD). There was no statistically significant difference between both the methods (P < 0.001). The coefficient of repeatability was 0.43% while the coefficient of reproducibility was 0.377% for the Galilei.Conclusion:Objective, noncontact measurement of the CCT with the Galilei dual Scheimpflug analyzer was convenient, had excellent intraoperator repeatability and interoperator reproducibility, and findings were similar to those obtained with standard US pachymetry.

Electrocatalytic oxidation and determination of hydrazine on nickel hexacyanoferrate nanoparticles-modified carbon ceramic electrode

In this study a carbon ceramic electrode (CCE) modified with nickel hexacyanoferrate (NiHCF) nanoparticles was developed. This electrode has a good sensitivity and electrocatalytic activity toward oxidation of hydrazine in a wide concentration range. The hydrazine oxidation mechanism on the electrode surface was investigated, which the overall number of electrons involved in the electrocatalytic oxidation was four. Detection limit of this electrode was 8 μM and relative standard deviation for 13 independent measurements was 5.77%. Finally the proposed electrode exhibited several advantageous features, including simple preparation, fast response time, good stability and repeatability. The electrode was successfully applied for determination of hydrazine in water samples.

On the nature of aerosols produced during a severe accident of a water-cooled nuclear reactor

Particle behaviour depends strongly on classic characteristics, e.g., size, and less macroscopic ones involving structure and composition these being especially important in situations of strong differential forces on a particle, i.e., surface impact or intensely-shearing flows. The former situation may lead to particle deposition or break-up and re-entrainment (with potential accident-management implications). This paper reviews information on aerosols from prototypical experiments identifying common features and typical variations. It emerges that a particle comprising one-third metal, one-third metal oxide and one-third a mixture of fission-product species would not be out of place in any potential reactor-accident sequence. Particle shapes appear relatively compact without branching chain-like structures. On size and structure, aerosols in the upstream part of the primary circuit would comprise a near-lognormal population with AMMD no more than 2 μm and geometric standard deviation around 2, particles comprising agglomerates of highly-coordinated clusters as small as 0.1 μm. In the containment, aerosols can typically be represented by primary-circuit particles and their agglomerates though particular circumstances (core–concrete interaction, hot-leg accident sequence) can alter this simple picture.

Human Nasal Cartilage Ultrastructure: Characteristics and Comparison Using Scanning Electron Microscopy

Human nasal cartilage is hyaline cartilage, although the function and loads placed on it are different depending on the location. We hypothesized that important differences exist between the nasal septal cartilage and lower lateral cartilage (LLC) ultrastructures. Such differences would be important in the field of cartilage engineering. Ten specimens (6 septum and 4 LLC) of cartilage from patients undergoing nasal surgery (rhinoplasty or septoplasty) were obtained and examined using scanning electron microscopy. Micrographs were then analyzed and measured using photograph analysis software. The collagen fibers of septal cartilage were found to be arranged in a mesh framework, with larger lacunae and thicker fibers measuring 3.18 microm (standard deviation = 0.75 microm), with a 99.9% confidence interval of 2.74 to 3.54 microm. LLC fibers, on the other hand, were arranged in less-organized sheets, with fibrous extensions, and had fewer, narrower lacunae. The fibers from the LLC averaged 2.29 microm, with a 99.9% confidence interval of 1.17 to 3.42 microm. Significant ultrastructural differences exist between the cartilage of the nasal septum and LLC. These are almost certainly the result of their embryologic origins and different forces placed on the structures they support. A less-organized pattern with smaller collagen fibers is present in the LLC versus the more-organized, layered, thicker collagen fibers of the septum. These differences may prove to be critical in the future of cartilage engineering.

An optical method for in situ characterization of fouling during filtration

AbstractIn dead‐end ultrafiltration, in situ characterization of fouling is of great importance to be able to evaluate cake properties during filtration runs. Moreover, local information is necessary to analyze and model the basic mechanisms involved in deposit formation. Many studies have investigated cake formation on flat‐sheet membranes but there is a lack of methods suitable for confined geometries such as inside‐out hollow‐fiber membranes. This study focuses on development and validation of an optical method using a laser sheet for in situ cake characterization in a narrow channel. The method enables the measurement of time‐variations of cross‐section cake thickness ranging from 10 μm to hundreds of micrometers with a 3 μm resolution and a 2.5 μm standard deviation. The reproducibility of the results and the order of magnitude are discussed on the basis of experimental results for clay suspensions. Limitations of the method are investigated; in the range of 0–2 g/l for clay suspensions, suspension concentration has no effect. Finally, future applications of the method as a tool for dead‐end fouling characterization are considered. © 2007 American Institute of Chemical Engineers AIChE J, 2007

A 6-Month Inhalation Study to Characterize the Toxicity, Pharmacokinetics, and Pharmacodynamics of Human Insulin Inhalation Powder (HIIP) in Beagle Dogs

The purpose of this study was to characterize the toxicity, pharmacokinetics, and pharmacodynamics of human insulin inhalation powder (HIIP) in beagle dogs when administered daily as an aerosolized dry powder formulation for 26 weeks via head-only inhalation. Conscious beagle dogs were exposed for 15 mins/day to an air control, placebo, maximal placebo (approximately three-fold the placebo dose), or one of three doses of HIIP (mean inhaled doses of 80, 240, or 701 microg/kg/day for the HIIP-low, HIIP-mid, and HIIP-high dose, respectively), The mass median aerodynamic diameters (MMAD) were between 2 and 3 microm and geometric standard deviation (GSD) values were approximately 2 across the groups, which is the ideal size range for favorable lung deposition. All groups were comprised of four dogs/sex, with the air control, HIIP-high, and maximal placebo groups having an additional two dogs/sex as recovery subgroups. Concentrations of serum insulin and glucose were determined from blood samples obtained following the first and last exposure for evaluation of the pharmacokinetics and pharmacodynamics of HIIP. Dose-related exposure (C(max), AUC) to inhaled insulin was observed with rapid absorption and no apparent gender differences or accumulation after repeated inhalation exposures for 26 weeks. The expected pharmacological effect of insulin was observed with dose-related decreases in serum glucose levels following HIIP administration. There were no toxic effects observed including no HIIP or placebo treatment-related effects on mean body weights, absolute body weight changes, clinical observations, food consumption, respiratory function parameters, ophthalmic examinations, electrocardiograms, heart rates, clinical pathology, or urinalysis. Similarly, there were no HIIP or placebo treatment-related effects on pulmonary assessments that included respiratory function parameters, bronchial alveolar lavage assessments, organ weights, or macroscopic and microscopic evaluations, including lung cell proliferation indices. HIIP was considered to have either low or no immunogenic potential in dogs. The no-observed-adverse-effect level (NOAEL) and maximum tolerated dose were the average inhaled dose of 701 microg insulin/kg/day.

Some ice nucleation characteristics of Asian and Saharan desert dust

Abstract. The large (7 m×4 m cylinder, 84 m3) AIDA (Aerosol Interactions and Dynamics in the Atmosphere) cloud chamber facility at Forschungszentrum, Karlsruhe, Germany was used to test the ice nucleating ability of two desert dust samples from the Sahara and Asia. Aerosol samples were lognormally distributed with a mode diameter of 0.4(±0.1) μm and geometric standard deviation of ~1.7(±0.2). At temperatures warmer than −40°C droplets were formed before ice crystals formed and there was generally no deposition nucleation observed. At temperatures colder than −40°C both dust samples exhibited dual nucleation events that were observed during the same expansion experiment. The primary nucleation event occurred at ice saturation ratios of 1.1 to 1.3 and is likely to be a deposition nucleation mode. The secondary nucleation event occurred at ice saturation ratios between 1.35 and 1.5. We cannot categorically determine whether this ice nucleation event is via a further deposition mode or a condensation mode, but the presence of some soluble material in the dust samples leads us to favour the latter process. The activated fractions of desert dust ranged from ~5–10% at −20°C to 20–40% at temperatures colder than −40°C. There was no obvious difference between the nucleation behaviour of the two dust samples.

Efficiency of the deposition mode ice nucleation on mineral dust particles

Abstract. The deposition mode ice nucleation efficiency of various dust aerosols was investigated at cirrus cloud temperatures between 196 and 223 K using the aerosol and cloud chamber facility AIDA (Aerosol Interaction and Dynamics in the Atmosphere). Arizona test dust (ATD) as a reference material and two dust samples from the Takla Makan desert in Asia (AD1) and the Sahara (SD2) were used for the experiments at simulated cloud conditions. The dust particle sizes were almost lognormally distributed with mode diameters between 0.3 and 0.5 μm and geometric standard deviations between 1.6 and 1.9. Deposition ice nucleation was most efficient on ATD particles with ice-active particle fractions of about 0.6 and 0.8 at an ice saturation ratio Si&lt;1.15 and temperatures of 223 and 209 K, respectively. No significant change of the ice nucleation efficiency was found in up to three subsequent cycles of ice activation and evaporation with the same ATD aerosol. This indicates that the phenomenon of preactivation does not apply to ATD particles. The desert dust samples SD2 and AD1 showed a significantly lower fraction of active deposition nuclei, about 0.25 at 223 K and Si&lt;1.35. For all samples the ice activated aerosol fraction could be approximated by an exponential equation as function of Si. This indicates that deposition ice nucleation on mineral particles may not be treated in the same stochastic sense as homogeneous freezing. The suggested formulation of ice activation spectra may be used to calculate the formation rate of ice crystals in models, if the number concentration of dust particles is known. More experimental work is needed to quantify the variability of the ice activation spectra as function of the temperature and dust particle properties.

Inhalable alginate nanoparticles as antitubercular drug carriers against experimental tuberculosis

Pharmacokinetic and chemotherapeutic studies have been carried out with aerosolised alginate nanoparticles encapsulating isoniazid (INH), rifampicin (RIF) and pyrazinamide (PZA). The nanoparticles were prepared by cation-induced gelification of alginate and were 235.5 ± 0 nm in size, with drug encapsulation efficiencies of 70–90% for INH and PZA and 80–90% for RIF. The majority of particles (80.5%) were in the respirable range, with mass median aerodynamic diameter of 1.1 ± 0.4 μm and geometric standard deviation of 1.71 ± 0.1 μm. The relative bioavailabilities of all drugs encapsulated in alginate nanoparticles were significantly higher compared with oral free drugs. All drugs were detected in organs (lungs, liver and spleen) above the minimum inhibitory concentration until 15 days post nebulisation, whilst free drugs stayed up to day 1. The chemotherapeutic efficacy of three doses of drug-loaded alginate nanoparticles nebulised 15 days apart was comparable with 45 daily doses of oral free drugs. Thus, inhalable alginate nanoparticles can serve as an ideal carrier for the controlled release of antitubercular drugs.

Optimization of the synthesis conditions of LiCoO 2 for lithium secondary battery by ultrasonic spray pyrolysis process

LiCoO 2 powders for lithium secondary battery were successfully prepared by the ultrasonic spray pyrolysis process. In this work, the statistical experimental design method was used to compare the characteristics (particle size, standard deviation, surface area, tab density) of the LiCoO 2 particles according to the four parameters (synthesis temperature, sintering temperature, sintering time, sintering heating rate). The optimal synthesis conditions for the synthesis of LiCoO 2 particles in ultrasonic spray pyrolysis process were to be obtained. The above-mentioned optimal conditions were used to prepare the particles with particle size 4.7 μm (standard deviation: ±1.3%) and the experimental results were in a good agreement with simulated values. The oxide powders were characterized by scanning electron microscopy, X-ray diffraction and electrochemical method including charge–discharge cycling. The characteristics as a cathode for lithium ion battery depended on the sintering temperature and sintering time. Consequently, LiCoO 2 powders made by the ultrasonic spray pyrolysis process displayed a good electrochemical performance and the experimental design method was well applied.

Sensitive Assay for Laboratory Evolution of Hydroxylases toward Aromatic and Heterocyclic Compounds

Powerful directed evolution methods have been developed for tailoring proteins to our needs in industrial applications. Here, the authors report a medium-throughput assay system designed for screening mutant libraries of oxygenases capable of inserting a hydroxyl group into a C-H bond of aromatic or O-heterocyclic compounds and for exploring the substrate profile of oxygenases. The assay system is based on 4-aminoantipyrine (4-AAP), a colorimetric phenol detection reagent. By using 2 detection wavelengths (509 nm and 600 nm), the authors achieved a linear response from 50 to 800 microM phenol and standard deviations below 11% in 96-well plate assays. The monooxygenase P450 BM-3 and its F87A mutant were used as a model system for medium-throughput assay development, identification of novel substrates (e.g., phenoxytoluene, phenylallyether, and coumarone), and discovery of P450 BM-3 F87A mutants with 8-fold improvement in 3-phenoxytoluene hydroxylation activity. This activity increase was achieved by screening a saturation mutagenesis library of amino acid position Y51 using the 4-AAP protocol in the 96-well format.

Characterization of MASDs of surface soils in north China and its influence on estimating dust emission

The micro-aggregated size distribution (MASD) of surface soil is an important parameter for modelling dust emission. However, there is no dataset of MASDs of all surface soil types in north China. The MASDs are here presented, measured by dry sieving, for typical surface soil samples, including sandy soil, gravelly sand soil, gravelly loam soil, loam soil and silt loam soil, collected from sandy deserts, Gobi deserts, oases, farmlands in steppe regions and steppe areas in north China. The MASDs of various surface soil types exhibit a combination of several log-normal distributions of five separated sizes with mean mass median diameters (MMDs) of 90, 210, 390, 600 and 980 μm, respectively, and mean standard deviations (SDs) of 1.25, 1.40, 1.25, 1.35 and 1.25 respectively. The log-normal distributions correspond to very fine sand, fine sand, medium sand, coarse sand and very coarse sand population. On the basis of characterization of the retrieved MASDs of various surface soil types in north China, dust emission fluxes are modelled by a dust production model (DPM model). It is shown that dust emission has been significantly influenced by MASDs. Fine sand and very fine sand are always associated with the highest dust emission fluxes. Emission fluxes of the medium sand, gravelly sand soil, gravelly loam soil and loam soil are lower than those of very fine sand and fine sand, but larger than those of the coarse sand. The differences in dust emission fluxes vary among the different soil types from 101 to 103 (μg · m−2 · s−1. Dust emission fluxes from sandy deserts and farmlands covered with sand sheets in north China rang from 101 to 104 μg · m−2 · s−1 while those from Gobi deserts, farmlands and steppes with gravelly desertification range from 101 to 102 μm · m−2 · s−1. The modelled results indicate that deserts and farmlands with sand are the major dust sources in north China.

Measured and Modeled Light Scattering Values for Dry and Hydrated Laboratory Aerosols*

Abstract Closure experiments were completed to compare measured and modeled aerosol optical properties and their dependence on controlled relative humidity (RH) and wavelength of light. NaCl, (NH4)2SO4, and NH4NO3 aerosol particles with approximate geometric mass mean diameters of 0.2 μm and geometric standard deviations of 1.7 were tested as part of this study. High evaporative losses (up to 40%) were observed for NH4NO3 aerosol at this particle size range due to heating, and the results from these tests have been excluded from the closure analysis. Aerosol optical properties were measured with a RH-scanning nephelometry system (humidograph) and modeled with a Mie–Lorentz light scattering model. Particle size distributions were measured with a scanning differential mobility analyzer. Closure between the measured and modeled values of the total light scattering coefficient (σsp), backscatter ratio (b), and Angstrom exponent (a) for dry (low RH) aerosols was achieved within 0.0%–5%, 4%–15%, and 3%–17%, res...

Preparation of a Hollow Microsphere Composed of Porous Organic-Inorganic Hybrid Wall in a W/O Microemulsion System

Abstract Hollow microspheres composed of organic-inorganic hybrid wall (polyorganosiloxane) have been synthesized as a new material in a W/O emulsion system from organosilanes. The average diameter of spheres for a typical run is 1.8 μm (standard deviation = 0.84) with a large spherical cavity in them and thermally stable at least up to 400 °C in air. The polyorganosiloxane wall is amorphous and becomes porous by treating at around 400 °C in air.

Factors Affecting the Deposition of Inhaled Porous Drug Particles

Recent findings indicate that the inhalation of large manufactured porous particles may be particularly effective for drug delivery. In this study, a mathematical model was employed to systematically investigate the effects of particle size, particle density, aerosol polydispersity, and patient ventilatory parameters on deposition patterns of inhaled drugs in healthy human lungs. Aerodynamically similar particles with densities of 0.1, 1.0, and 2.0 g/cm3 were considered. Particle size distributions were defined with mass median aerodynamic diameters (MMADs) ranging from 1 to 3 μm and geometric standard deviations ranging from 1.5 to 2.5, representing particles in the respirable size range. Breathing rates of 30 and 60 L/min with tidal volumes of 500 to 3000 mL were assumed, simulating shallow to deep breaths from a dry powder inhaler. Particles with a high density and a small geometric diameter had slightly greater deposition fractions than particles that were aerodynamically similar, but had lower density and larger geometric size (typical of manufactured porous particles). This can be explained by the fact that particles with a small geometric diameter deposit primarily by diffusion, which is a function of geometric size but is independent of density. As MMAD increased, the effect of density on deposition was less pronounced because of the decreased efficiency of diffusion for large particles. These data suggest that polydisperse aerosols containing a significant proportion of submicron particles will deposit in the pulmonary airways with greater efficiency than aerodynamically similar aerosols comprised of geometrically larger porous particles. © 2002 Wiley‐Liss Inc. and the American Pharmaceutical Association J Pharm Sci 91:1590–1600, 2002

REMOVAL DYNAMICS OF AIRBORNE ROAD DUST IN A VENTILATED AIRSPACE

ABSTRACT We derive a simple linear dynamic equation to describe the removal mechanisms of airborne road dust from a ventilated airspace. The dynamic equation is sufficiently to take into account the simultaneous removal effects of turbulent coagulation, turbulent diffusive deposition, gravitational sedimentation, and airflow pattern within a ventilated airspace. Three dimensionless parameters TC, TD, and GS that characterize the relative effects of turbulent coagulation, turbulent diffusive deposition and gravitational settling, respectively, in a ventilated airspace were introduced to generalize the removal dynamics of airborne road dust. An environmental chamber test was carried out not only to determine the particle size distributions but also to verify the removal dynamics of airborne road dust in a ventilated airspace. Our results demonstrate that there is no significant variation for particle size distributions of road dust obtained from urban and suburban areas in north Taiwan region and both followed a lognormal distribution with average geometric mean diameter of 1.08 ± 0.02 µm and geometric standard deviation of 2.59 ± 0.03. Measured values match the simulated values with an r 2 value of 0.93, whereas the overall RMSE value of 2.36 ± 1.05 mg m−3 is low, indicating that the ability to predict the removal dynamics of airborne road dust within a ventilated airspace using an average particle size based linear equation. Effects of TC, TD, GS, and various ventilation systems on the time-dependent road dust concentrations are also justified.