Influence of velocity and surface temperature of alumina particles on the properties of plasma sprayed coatings

In this paper are described the main characteristics of the plasma spraying process of alumina deposits, i.e., the temperature and flow field of the plasma jets obtained with the classical spraying torches, the injection of the particles into the plasma jet, the particle surface temperature and velocities in the plasma (measured for calibrated alumina particles), and the coating generation. The measurements on the alumina particles are compared with the predictions of a mathematical model. The experimental and computed particle velocities are in rather good agreement. However, this is not the case for the particle surface temperature. Possible reasons for the discrepancy are proposed (influence of the carrier gas, thermophoretic forces, and poor penetration of the particles into the plasma core even for an injection velocity twice that of the optimal calculated one, as shown by recent measurements). Finally the correlations between the particle velocities and surface temperature, and the properties of the alumina coating (porosity, crystal structure, mechanical properties) are studied.     

Transport efficiency in femtosecond laser ablation inductively coupled plasma mass spectrometry applying ablation cells with short and long washout times

Relative mass transport efficiencies of near infrared (λ = 795 nm) femtosecond laser generated brass aerosols in helium were measured by ICP-MS applying different ablation cells with short and long washout times. It was found that the transport efficiencies are independent of the cell used within the mutual experimental uncertainties. This finding was confirmed by additional measurements providing the absolute particle mass transport efficiencies of femtosecond laser ablation in He. Here, the transport efficiencies were determined by weighing the samples before and after ablation with a micro-balance, collecting the particles by low-pressure impaction, and evaluating the impacted masses quantitatively by total reflection X-ray fluorescence. Within the experimental uncertainties (± 9–19%) the same absolute transport efficiency (about 77%) was found for all cells applied. This efficiency value can be regarded as a lower limit of the absolute mass transport efficiency since mass losses in the impactor are difficult to quantify.     

INTROMISSION OF WATER-REPELLENT AND HYDROSCOPIC PROPERTIES SIMULTANEOUSLY TO PP BY PLASMA DISCHARGE METHOD

Plasma-induced surface graft copolymerization of acrylic acid on polypropylene non-woven fabric (PP-g-AA) and polypropylene membrane were reported. The extents of grafting were controlled by the plasma and polymerization condition. Hexadecyltrimethyl ammonium bromide was then coupled with the carboxyl group of PP-g-AA to obtain a polyion complex (PIC). At last, CF4 plasma was used to give PICs hydrophobic property. The moisture regain and water-repellency of the processed PICs was investigated. The surfaces were characterized using ATR FT-IR and XPS. The result indicates that the products have very high ability to adsorb moisture, even better than cotton fiber. At the same time, the products show excellent hydrophobic property, which can‘t be wetted by those reagents whose surface tensions were higher than 327mN/m.     

Screening, library-assisted identification and validated quantification of 23 benzodiazepines, flumazenil, zaleplone, zolpidem and zopiclone in plasma by liquid chromatography/mass spectrometry with atmospheric pressure chemical ionization

A liquid chromatographic/mass spectrometric assay with atmospheric pressure chemical ionization (LC/APCI-MS) is presented for fast and reliable screening and identification and also for precise and sensitive quantification in plasma of the 23 benzodiazepines alprazolam, bromazepam, brotizolam, camazepam, chlordiazepoxide, clobazam, clonazepam, diazepam, flunitrazepam, flurazepam, desalkylflurazepam, lorazepam, lormetazepam, medazepam, metaclazepam, midazolam, nitrazepam, nordazepam, oxazepam, prazepam, temazepam and tetrazepam, triazolam, their antagonist flumazenil and the benzodiazepine BZ1 (omega 1) receptor agonists zaleplone, zolpidem and zopiclone. It allows confirmation of the diagnosis of an overdose situation and monitoring of psychiatric patients' compliance. The analytes were isolated from plasma using liquid-liquid extraction and were separated on a Merck LiChroCART column with Superspher 60 RP Select B as the stationary phase. Gradient elution was performed using aqueous ammonium formate and acetonitrile. After screening and identification in the scan mode using the authors' LC/MS library, the analytes were quantified in the selected-ion monitoring mode. The quantification assay was fully validated. It was found to be selective proved to be linear from sub-therapeutic to over therapeutic concentrations for all analytes, except bromazepam. The corresponding reference levels the assay's accuracy and precision data for all studied substances are listed. The accuracy and precision data were within the required limits with the exception of those for bromazepam. The analytes were stable in frozen plasma for at least 1 month. The validated assay was successfully applied to several authentic plasma samples from patients treated or intoxicated with various benzodiazepines or with zaleplone, zolpidem or zopiclone. It has proven to be appropriate for the isolation, separation, screening, identification and quantification of the drugs mentioned above in plasma for clinical toxicology, e.g. in cases of poisoning, and forensic toxicology, e.g. in cases of driving under the influence of drugs.     

A comparative study between inductively and capacitively coupled plasma deposited polystyrene films: chemical and morphological characterizations

Thin polystyrene films were deposited on stainless steel substrates by capacitively and inductively coupled radio frequency glow discharge plasma, in order to compare their chemical and morphological properties. The films were characterized by Fourier‐transform infrared spectroscopy (FTIR), X‐Ray photoelectron spectroscopy (XPS), time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS), atomic force microscopy (AFM) and scanning electron microscope (SEM). Wettability properties were also determined by contact angle measurements. Ageing effect was studied by analysing films aged for 15 min and for 1 week. Results from both capacitively and inductively plasma polymerized polystyrene (pPS) films aged for 15 min showed that the chemical structure of the bulk, chemical composition of the surface (depth < 10 nm) and wettability properties were rather similar. Only their microstructures were very different: the pPS_capa film's microstructure showed homogeneous distribution of spherical particles of about 100 nm in diameter but the pPS_ind film's microstructure seemed to be mainly influenced by the surface of the metallic substrate: orientated ‘lamellae‐like layers’ of polymers were observed on each metallic grain. Ageing for 1 week in ambient air induced low oxygen uptake in the surface of both pPS films. The pPS_ind topmost surface (depth < 3 nm) was more oxidized than that of pPS_capa but no modification of the chemical structure of the bulk or of the morphology was noticed after ageing. Copyright © 2006 John Wiley & Sons, Ltd.     

激光等离子体反应生成的AgP+n、AumP+n的结构分析

原子簇化合物的合成方法,由于条件限制,只有B、C、St等非金属元素与过渡金属袈基化合物等较为成熟．贵金属原子簇的合成则较困难．然而,应用激光等离子体反应,可使周期表内几乎所有元素都生成原子簇,为原子簇的生成与研究提供了一条新途径．该方法生成的原子簇在飞行时间质谱仪上可记录到一系列信号,某些信号呈现区域极大（或被称为‘匈数’吵］．郑兰芬等用纯化的红磷粉分别与金粉、银粉混合,在激光等离子作源飞行时间质谱仪上得到一系列谱图【2］：ig与P作用只得到单核xg与P形成的lgy：iE离子簇．谱图较简单,＊沪X最大可达叱叱…     

Heat transfer from a rarefied plasma flow to a metallic or nonmetallic particle

Heat transfer from a plasma flow to a metallic or nonmetallic spherical particle is studied in this paper for the extreme case of free-molecule flow regime. Analytical expressions are derived for the heat flux due to, respectively, atoms, ions, and electrons and for the floating potential on the sphere exposed to a two-temperature plasma flow. It has been shown that the local or average heat flux density over the whole sphere is independent of the sphere radius and approximately in direct proportion to the gas pressure. The presence of a macroscopic relative velocity between the plasma and the sphere causes substantially nonuniform distributions of the local heat flux and enhances the total heat flux to the sphere. The heat flux is also enhanced by the gas ionization. Appreciable difference between metallic and nonmetallic spheres is found in the distributions along the oncoming flow direction of the floating potential and of the local heat flux densities due to ions and electrons. The total heat flux to the whole sphere is, however, almost the same for these different spheres. For a fixed value of the electron temperature, the heat flux decreases with increasing temperature ratio T_e/T_h.     

液-液萃取电感耦合等离子体质谱法测定天然水中痕量稀土元素

建立了以单、二（2－乙基己基）磷酸酯混合螯合剂的庚烷溶液作为萃取剂，6.0mol/L HCl反萃取预分离富集，In和Rh做内,ICP-MS测定天然水中15种稀土元素的分析方法。方法的富集倍数为200倍，各元素的检出限范围在0.01-1.8ng/L之间，相对标准偏差RSD＜5％，萃取回收率＞93％。     

Determination of clindamycin in animal plasma by high-performance liquid chromatography combined with electrospray ionization mass spectrometry

A method for the quantification of clindamycin in animal plasma using high-performance liquid chromatography combined with electrospray ionization mass spectrometry (LC/ESI-MS/MS) is presented. Lincomycin is used as the internal standard. The sample preparation includes a simple deproteinization step with trichloroacetic acid. Chromatographic separation is achieved on an RP-18 Hypersil column using gradient elution with 0.01 M ammonium acetate and acetonitrile as mobile phase. Good linearity was observed in the range 0-10 microg ml(-1). The limit of quantification of the method is 50 ng ml(-1) and the limit of detection is 1.3 ng ml(-1). The method was shown out to be of use for pharmacokinetic studies of clindamycin formulations in dogs.     

Slurry nebulization ICP-AES spectrometry method for the determination of tin in organotin(IV) complexes

This paper proposes a quick, novel method for tin determination in organotin chemicals by slurry nebulization inductively coupled plasma atomic emission (ICP-AES) spectrometry. The method was tested by the measurement of five organotin carboxylate complexes of known composition for obtaining simple stoichiometric data. The slurries were prepared by first dissolving the organotins in an adequate solvent (methanol, pyridine or acetone) well miscible with water and then adding this solution drop-by-drop to a 0.005% TX-100 tenzide solution while maintaining intensive mixing. Dynamic laser light scattering experiments showed that the average equivalent particle size in the resulting slurry was ≈0.3 μm for all samples and solvents. Under suitable ICP-AES measuring conditions, the signal recoveries were found to be between 101.8 and 106.6%, which allowed direct nebulization and calibration against aqueous solutions. Typically, 70 μg l⁻¹ detection limit and 1–5% relative S.D. on five replicates can be achieved by the described method.