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1.
Daryl L. Roberts 《Aerosol science and technology》2013,47(11):1119-1129
We describe a general theory of multi-nozzle cascade impactor stages and show how testers of inhaled drug products, such as metered-dose or dry-powder inhalers, can decide, solely from the stage nozzle dimensions, whether any used impactor is satisfactorily operating within its expected aerodynamic performance range. We first account for the realistic shape of particle collection efficiency curves and show that the effective diameter, described by Roberts and Romay (2005), is sufficiently accurate as the primary indication of the aerodynamic performance.To ensure that a used impactor is performing in the same aerodynamic range allowed for new impactors, one must also satisfy the other, more secondary factors of cascade impaction aerodynamics, most notably the distance to the collection surface relative to the nozzle diameter. We show what this constraint means in practice for used Next Generation Impactors (NGIs; Marple et al. 2003a, b; 2004), and show that partially occluded nozzles are the most likely nozzles to fail this test.Applying this principle that used impactors should perform in the same aerodynamic range as new impactors, we derive constraints on the nozzle diameters of any used NGI (Table 6, main text). We can partially apply this principle to other common impactors used for inhaler testing, such as the Andersen and the Marple-Miller, but are hindered by the absence of a published acceptable range for the distance to the impaction collection surface and by the limited published information on the shape of their stage collection efficiency curves. 相似文献
2.
《Journal of Sulfur Chemistry》2013,34(5):549-558
Synthesis of a new class of 1, 3-thiazolidine nucleoside analogs is described. Reaction of 2-amino-2-deoxy-D-glucopyranose hydrochloride 2 with carbon disulfide yielded 5-hydroxy-4-(D-arabino-1, 2, 3, 4-tetrahydroxybutyl)-thiazolidin-2-thione 3, which on acetylation yielded 5-acetoxy-4-(D-arabino-1, 2, 3, 4-tetraacetoxy-butyl)-thiazolidin-2-thione 4. The acetylated sugar 4 reacted with hydrazonoyl chlorides 1a–f, affording the 5-acetoxy-4-(D-arabino-1, 2, 3, 4-tetraacetoxybutyl)-spiro-1 3thiazolidine-2,2′ -1 3 4thiadiazole derivatives 8a–f. The antibacterial activity of the novel 1, 3-thiazolidine-2,2′ -spiro- 1 3 4thiadiazole nucleoside analogs is highlighted. All compounds with free NH group in the thiazolidine series 8a–f showed significant biological activity against all the standard strains. 相似文献
3.
This paper describes the usefulness of one-dimensional diffusion-ordered NMR spectroscopy (1D-DOSY) in investigating dynamics and interactions of molecules in solution as well as in analyzing the structure of molecules. We synthesized the three imines, N-benzylidene-4-methylbenzene-Sulfonamide (1), N-(4-chloro-benzylidene)4-methyl-benzene-sulfonamide (2), and N- (4-methoxybenzylidene)-4-methyl-benzene sulfonamide (3), and acetophenone (4) and its three derivatives, 4-chloroacetophenone (5), 4-nitro-acetophenone (6), and 4-methoxyaceto -phenone (7). 1D-DOSY was applied to a mixture of compounds (1), (2), and (3) and to a mixture of compounds (4), (5), (6), and (7). Although 1 H NMR chemical shifts of the molecules in the mixtures resembled one another in the surrounding, we could distinguish signals of the individual molecules in each mixture on the basis of the NMR data and the values of the diffusion coefficient. Also, we could found the correlation of the measured diffusion coefficients and the calculated molecular volumes. 相似文献
4.
The numerical models for predicting the collection efficiency of particles in the size range of 0.3 ~ 10.0 μm in electrostatic precipitators (ESPs) have been well developed. However, for nanoparticles, or particles with the diameter below 100 nm, the existing models can't predict the collection efficiency very well because the electric field and ion concentration distribution were not simulated, or charging models were not adopted appropriately to calculate particle charges. In this study, a 2-D numerical model was developed to predict the nanoparticle collection efficiency in single-stage wire-in-plate ESPs. Laminar flow field was solved by using the Semi-Implicit Method for Pressure-Linked Equation (SIMPLER Method), while electric field strength and ion concentration distribution were solved based on Poisson and diffusion-convection equations, respectively. The charged particle concentration distribution and the particle collection efficiency were then calculated based on the convection-diffusion equation with particle charging calculated by Fuchs diffusion charging theory. The simulated collection efficiencies of 6–100 nm nanoparticles were compared with the experimental data of Huang and Chen (2002) for a wire-in-plate dry ESP (aerosol flow rate: 100 L/min, applied voltage: ?15.5 ~ –21.5 kV). Good agreement was obtained. The simulated particle collection efficiencies were further shown to agree with the experimental data obtained in the study for a wire-in-plate wet ESP (Lin et al. 2010) (aerosol flow rate: 5 L/min, applied voltage: +3.6 ~+4.3 kV) using monodisperse NaCl particles of 10 and 50 nm in diameter. It is expected that the present model can be used to facilitate the design of ESPs for nanoparticle control and electrostatic nanoparticle samplers. 相似文献
5.
Ronald G. Harvey Qing Dai Chongzhao Ran Keunpoong Lim Ian Blair Trevor M. Penning 《Polycyclic Aromatic Compounds》2013,33(5):371-391
Syntheses are reported for: (1) adducts of the quinone metabolites of benzo[a]pyrene (BPQ) and benz[a]anthracene (BAQ) with 2′-deoxyadenosine and 2′-deoxyguanosine; (2) 15 N-labelled analogs of these adducts (four or five nitrogen atoms 15 N-labelled); (3) depurinated adducts of BPQ and BAQ with adenine or guanine covalently linked to the N7 or N9 positions of the purine bases; (4) 13 C-labelled derivatives of benzo[a]pyrene, BPQ, benzo[a]pyrene trans-7,8-dihydrodiol, and the benzo[a]pyrene anti-diol epoxide (with 13 C-atoms at the 5- and 11-positions); and (5) depurinated adducts formed by reactions of the benzo[a]pyrene radical-cation at the C 8 -, N 7 -, and N 9 -positions of adenine and guanine. 相似文献
6.
An aerosol dynamics model for dry deposition process is developed based on the moment method. Since it is hard to fully apply the moment method to the widely used dry deposition velocity expressions based on the resistance theory, the dry deposition velocity expression by Raupach et al. (2001) is used. Detailed deposition mechanisms such as Brownian diffusion, gravitational settling, and impaction are considered in the expression. To verify the validity of the derived dynamic equation, aerosol dynamics for the dry deposition process is estimated with the expressions of Raupach et al. (2001), of Wesely (1989) modified for particles (Seinfeld and Pandis 1998), in CMAQ, and with constant value used in RAINS-ASIA. Those expressions give different dynamics. Generally, the result for this study is between the result of modified Wesely's expression and CMAQ. When using the modified Wesely's expression with the number of sections being equal or smaller than 10, the resultant size distribution does not give the peak shape accurately. 相似文献
7.
《Journal of Sulfur Chemistry》2013,34(4-5):381-391
Pyridine-2(1H)-thione 1 reacted with phenyl isothiocyanate to give pyrido[2,3-d]pyrimidine derivative 3. Compound 3 reacted with halogen containing compounds 4a–d and methyl iodide in dimethylformamide/potassium hydroxide solution at room temperature to give 2,7-bisalkylthiopyrido[2,3-b]pyrimidine derivatives 5a–d and 9, respectively. Compounds 5a–d could be cyclized into thienopyrido[2,3-d]pyrimidine derivatives 6a–d by boiling with ethanolic potassium hydroxide solution. Compound 6a reacted with acetic anhydride or formic acid and gave the corresponding pyrimido[4″,5″:4′,5′]thieno[3′,2′:5,6]pyrido[2,3-d]pyrimidine derivatives 8a,b. Compound 9 reacted with hydrazine hydrate to yield pyrazolo[4′,3′:5,6]pyrido[2,3-d]pyrimidine derivative 11 which could be reacted with nitrous acid and dimethylformamide-dimethylacetal (DMF-DMA) and gave the final isolable products corresponding to the pyrazolo[4′,3′:5,6]pyrido[2,3-d]tetrazolo-[5,1-b]pyrimidine and pyrimido[1″,2″:1′,5′]pyrazolo[4′,3′:5,6]pyrido[2,3-d]1 2 4triazolo-[4,3-b] pyrimidine derivatives 13 and 17, respectively. Compound 11 also reacted with some β-dicarbonyl compounds such as acetylacetone (18) and ethyl acetoacetate (20) to yield the corresponding pyrimido[1″,2″:1′,5′]pyrazolo[4′,3′:5,6]pyrido[2,3-d]pyrimidine derivatives 19 and 21, respectively. Finally, compound 11 reacted with chloroacetyl chloride (22) to give the corresponding imidazo[1″′,2″′:1″,5″]pyrazolo[4″,3″:5′,6′]pyrido[3′,2′:5,6]pyrimido[2,1-c]1 2 4triazine derivative 23. 相似文献
8.
《分离科学与技术》2012,47(2):264-276
A group of nearly forty-eight (48) of surfactants based on ionic liquids (ILs) has been described. The physicochemical and interfacial behavior for several of these IL-based surfactants has been reported since 2004. This review attempts to summarize the important applications that IL-based surfactants have had in analytical chemistry and separation science. Thus, they have been successfully used as extractant systems as substitutes to conventional organic solvents in extraction schemes, or by modifying the chemical structure of conventional extractant sorbents. The analytical performance of these novel IL-based surfactants has been shown to be better than conventional solvents and even better than conventional cationic surfactants. IL-based surfactants have also been used as mobile phase and stationary phase modifiers in high-performance liquid chromatography (HPLC), as modifiers of the electrokinetic chromatographic (EKC) medium, or as the micellar component in capillary electrophoresis (CE). Thus, IL-based surfactant methods constitute a promising and developing area within separation science. 相似文献
9.
S. J. Dunnett X. Wen S. K. Zaripov R. S. Galeev M. V. Vanunina 《Aerosol science and technology》2013,47(7):490-502
The performance of an idealized spherical sampler facing both vertically upwards and downwards in calm air is studied numerically. To describe the air flow around the sampler, both potential and viscous flow models have been adopted. The equations of particle motion are then solved to calculate the aspiration efficiency. The dependence of the aspiration efficiency upon the various parameters of importance in calm air sampling are investigated and compared where possible with the experimental work of Su and Vincent (2003, 2004a, b). It is found that in the case of upwards sampling the bluntness of the sampler only has a significant effect upon aspiration for large sampling velocities, values that would not generally be physically realistic. In the case of downwards sampling an important non-dimensional quantity, B 2 R C , is identified, where B represents the sampler bluntness and R C represents the gravitational effects. This quantity determines the physical conditions for which aspiration will not occur and also the limiting values of the aspiration efficiency when aspiration does occur. In the case of low sampling velocities a difference is noted between experimental and numerical results for aspiration efficiency raising the need for more experimental data in this area. For both upwards and downwards sampling the semi-empirical models of Su and Vincent (2004b) have been modified to account for the information gained from the study. This is particularly important in the downwards sampling case where the modified model is found to agree particularly well with the results obtained. 相似文献
10.
The hypothesis that hydroxylation of the 7-methyl group is the first step in metabolic activation of 7,12-dimethylbenz[a]anthracene (DMBA) was advanced over three decades ago (1, 2). A considerable body of evidence supports the hypothesis (3). A chemical model for the oxidative metabolism of DMBA may be useful in understanding the mechanism of metabolic activation of DMBA and other methylated carcinogenic hydrocarbons, particularly the first step. Here we show that a nonenzymatic one-electron oxidation pathway transforms DMBA to carcinogenic alcohol and meso-aldehyde metabolites. The results are consistent with the hypothesis that hydroxylation of the 7-methyl and/or 12-methyl groups is the first metabolic step in DMBA activation. The hypothesis predicts that hydroxylation of other meso-methyl-substituted hydrocarbons is the first essential step in the metabolic activation of methylated carcinogenic hydrocarbons. 相似文献
11.
Abstract We present a geometrical method for analyzing sequential estimating procedures. It is based on the design principle of the second-order efficient sequential estimation provided in Okamoto et al. (1991). By introducing a dual conformal curvature quantity, we clarify the conditions for the covariance minimization of sequential estimators. These conditions are further elaborated for the multidimensional curved exponential family. The theoretical results are then numerically examined by using typical statistical models, von Mises-Fisher, and hyperboloid models. 相似文献
12.
Abstract We discuss the performance of “closed-end” fluctuation tests, used to detect changes in the structural stability of a model, in the case where the time horizon is large and the observations do not possess high enough moments. It is demonstrated via a simulation study that, in the latter case, the choice of the boundary function should take into account the number of moments existing; otherwise the actual size of the test may exceed the nominal level. We suggest an alternative “open-end” fluctuation procedure and study its asymptotic behavior. It turns out that if an improper boundary function is chosen, then the null hypothesis may be rejected even if it is true. This means that an appropriate choice of the boundary function requires some prior information about the tail heaviness of the observations. This is different from the cumulative sum-based monitoring schemes suggested by Chu et al. (1996) and further studied by Horváth et al. (2004). 相似文献
13.
A variant of the Vienna DMA (Winklmayr et al. 1991; Reischl et al. 1997) with inner and outer electrode radii of 25 and 33 mm, and a conventional trumpet inlet diameter of 97 mm has been tested. It incorporates a reduced pressure drop sheath gas exhaust system that enables reaching flow rates approaching 4000 L/min. Several new additional flow features are included to delay the transition to turbulent conditions. A cylindrical geometry with a DMA length L of 97 mm (distance between the aerosol inlet and outlet slits) is seen to keep the flow laminar up to the highest Reynolds number achieved, though showing slight signs of flow quality deterioration at about Re = 20,000. An equally long DMA with an inner electrode shaped as a 5° cone caped by a spherical dome remains stable up to the highest Reynolds number achieved. It is expected to continue this trend to considerably higher flow rates. Both these long configurations exhibit line widths close to the ideal Brownian diffusion limit, reaching FWHH of 4% for a particle mass diameter of 1 nm. A short DMA with an axial length L of 18 mm and an inner electrode shaped as a 5° cone caped by an ellipse of 3/2 aspect ratio remains also laminar at the highest speeds attained, and exhibits FWHH as small as 2.4%. It departs moderately from ideal behaviour at small flow rates, presumably due to its non-cylindrical geometry. More serious departures observed at high Reynolds numbers may perhaps be due to flow unsteadiness radiated into the working section by sound waves from the turbulent exhaust region. This is the first report of a DMA capable of excellent resolution at 1 nm, yet with a sufficiently wide and long working section to enable (in principle) covering the size range up to 100 nm. 相似文献
14.
Shyamal K. De 《Sequential Analysis》2013,32(1):87-111
Abstract In this work, we present a modified three-stage sampling procedure to construct fixed-width confidence intervals of the common variance of equicorrelated normal distributions. We derive the exact distribution of the stopping variable of this sampling scheme and also the exact distribution of the estimator of the common variance at stopping. The modified three-stage sampling substantially reduces the expected sample size compared to that of the two-stage sampling scheme of Haner and Zacks (2013). The coverage probabilities of the proposed interval estimators are computed exactly and are compared with the coverage probabilities obtained by two-stage sampling. We derive exact formulae for the functionals of the stopping variable and the estimator of the common variance at stopping. 相似文献
15.
We have designed modified two-stage and purely sequential strategies to estimate the difference of location parameters from two independent negative exponential populations having unknown but proportional scale parameters under a modified Linex loss function. This article extends one-sample methodologies of Mukhopadhyay and Bapat (2016, Sequential Analysis). Some preliminary results are established along the lines of Mukhopadhyay and Hamdy (1984, Canadian Journal of Statistics) and Mukhopadhyay and Darmanto (1988, Sequential Analysis). We have resorted to Mukhopadhyay and Duggan (1997, Sankhya, Series A) in developing asymptotic second-order properties for the modified two-stage methodology and to nonlinear renewal theory of Lai and Siegmund (1977, 1979, Annals of Statistics) and Woodroofe (1977, Annals of Statistics) in addressing analogous properties under the purely sequential methodology. Then, we supplement with extensive sets of data analysis via computer simulations validating that both modified two-stage and purely sequential methods perform very well. Both methodologies are also illustrated and implemented using real datasets from cancer studies and reliability analysis. 相似文献
16.
《Journal of Sulfur Chemistry》2013,34(2):223-229
Herein, the chemistry of 2-aminothiophenol has been utilized in the synthesis of several interesting products such as oxidation and reaction with π-deficient compounds. On oxidizing 2-aminothiophenol by sodium hypochlorite furnishes 2-[(2-aminophenyl)-dithio]aniline. Treatment of the obtained product with acetyl chloride affords N-(2-[2-(acetylamino)-phenyl-disulphanyl)-phenyl]acetamide. Reaction of the former acetamide with POCl3 yields 2-methyl-1,3-benzothiazole. Moreover, (3,4,8,9)-dibenzo-2,7-dithia-5,10-diaza4 4 4propellane is formed on reacting the target 2-aminothiophenol with cyclohexane-1,2-dione, whereas its reactions with electron π-acceptors such as 2,3-dichloro-1,4-naphthoquinone (DCHNQ), 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), tetra-cyanoethylene (TCNE), and 1-(dicyanomethylen)acenaphthen-2-one yield various heterocycles. 相似文献
17.
18.
Dong Keun Song Hyuksang Chang Sang Soo Kim Kikuo Okuyama 《Aerosol science and technology》2013,47(8):701-712
The effect of Brownian diffusive particle trajectory of nanoparticles on the transfer function of the low pressure Differential Mobility Analyzer (LPDMA) was evaluated by a numerical simulation of the Langevin dynamic equation. The results of the simulation were compared with previously reported experimental results (Seto et al. 1997; Seol et al. 2000) and Stolzenburg's transfer function (1988). As the operational pressure decreased, the peak and FWHM (full width of the transfer function at half of its maximum) values of transfer function, as calculated by numerical simulation, were increased, which was not evident from Stolzenburg's transfer function. In comparison with the experiments of Seto et al., discrepancies in the higher electrical mobility regime than from central mobility were found, which could be caused by the incomplete flow control of their LPDMA. However, the transfer function, as calculated by numerical simulation was in good agreement with experimental results reported by Seol et al., performed with the improved LPDMA at well-controlled operation conditions. 相似文献
19.
Jamel Madiouli Jalila Sghaier Jean-José Orteu Laurent Robert Didier Lecomte Habib Sammouda 《Drying Technology》2013,31(12):1358-1364
A novel non-intrusive technique (stereo-correlation) was used to determine the apparent volume of a banana in convective drying condition. The volume was calculated using the 3D Digital Image Correlation method (3D-DIC), which provides the 3D shape of the banana during drying. The combination of this technique and mass measurement allows the calculation of the porosity using the model of Katekawa and Silva[ 1 ] and the graphical interpretation presented by Madiouli et al.[ 2 ] The banana shows an ideal shrinkage at the beginning of drying but stops shrinking at low moisture content, thus increasing the porosity up to 30–35%. The comparison of the experimental shrinkage and the calculated porosity with the experiments deduced from the literature enables us to conclude the effectiveness of the 3D-DIC technique as well as the porosity calculation model. 相似文献
20.
Atmospheric aerosols are one of the least understood components of the climate system and incur adverse health effects on susceptible populations. Organic aerosols can make up as much as 80% of atmospheric aerosols (Lim and Turpin 2002), and so its quantification and characterization plays an important role in reducing our uncertainty with regards to aerosol impacts on health and climate. As the number of organic molecules in the atmosphere are diverse in number (Hamilton et al. 2004), we advance a functional group representation of organic molecules as measured by Fourier transform infrared spectroscopy (FTIR) to characterize the chemical composition of particle samples. This study describes and evaluates the algorithm introduced by Russell et al. (2009) for apportionment and quantification of oxygenated (carbonyl and hydroxyl) functional groups from infrared absorption spectra. Molar absorptivities for carbonyl and hydroxyl bonds in carboxylic groups are obtained for several dicarboxylic compounds, and applied to a multifunctional compound and mixture to demonstrate the applicability of this method for more complex samples. Furthermore, functional group abundances of two aldehydic compounds, 2-deoxy-d-ribose and glyceraldehyde, atomized from aqueous solution are in quantitative agreement with number of bonds predicted after transformation of these compounds into diols. The procedure for spectra interpretation and quantitative analysis is described through the context of an algorithm in which contributions of background and analyte absorption to the infrared spectrum are apportioned by the superposition of lineshapes constrained by laboratory measurements. Copyright 2013 American Association for Aerosol Research 相似文献