Investigation of fluidized bed behaviour using electrical capacitance tomography

The temporal and cross-sectional distributions of particles in a 127 mm diameter fluidized bed have been obtained using a new generation, high-speed electrical capacitance tomography. Two planes of eight electrodes were used and mounted at 160 and 660 mm from the gas distributor which was a 3 mm thick porous plastic plate (maximum pore size of 50-70 μ m). 3 mm diameter, nearly-spherical polyethylene granules made up the bed. Experiments at sampling frequencies of 200-2000 cross-sections per second and gas superficial velocities from just below the minimum fluidization to 83% above minimum fluidization velocities were used. The time series of the cross-sectional average void fractions have been examined both directly and in amplitude and frequency space. The last two used probability density functions and power spectral densities. The information gathered shows that the fluidized bed was operating in the slugging mode, which is not surprising given the size of the particles. It has been found that an increase in the excess gas velocity above the minimum fluidization velocity resulted in an increase in the mean void fraction, an increase in the length and velocity of the slug bubbles as well as the bed height, and a slight decrease in the slug frequency. The results are presented in a level of detail suitable for comparison with later numerical simulation.     

Modification and ionic stimulation of hollow fiber membrane by electric field for water treatment

Hollow fiber membrane (HF) is considered one of the prevalent materials for water treatment; its effectiveness is controlled by permeation and mechanical characteristics. In this study, HF membrane surface was stimulated using electrochemical technique, where binary system of stainless steel cylinder and graphite rod electrodes was used into electrolytic solution of sodium acetate 0.1 M as electrolyte. Two pH of acidic medium (pH = 3.5) and alkaline medium (pH = 8.5) were prepared and different potential between 2 and 10 V were applied. EDX analysis of HF membrane surface revealed the formation of sodium ions on the surface of HF membrane with maximum content of Na⁺ ions 1.84%. Also, HF membrane surface showed variation of roughness (R _a) as, HF membrane surface may undergo distortion by using aggressive conditions of high electric potential (7.5–10 V), The measured raw HF membrane (R _a) was 34.8 nm, while, after electrochemical modification in alkaline medium R _a showed higher values 36, 37, and 41 nm using 2, 2.5, and 5 V, respectively. While, after electrochemical modification in acidic medium (R _a) showed 35, 39, 42, 49, 52 nm for 2, 2.5, 5, 7.5, and 10 V, respectively. Moreover, tensile strength Young's modulus, break stress and break strain were measured after electrochemical modification in both acidic and alkaline mediums and maximum porosity value 76.84% was observed after 30 min in acidic medium.     

The Effect of Spray-Freeze Drying of Montmorillonite on the Morphology,Dispersion, and Crystallization in Polypropylene Nanocomposites

The spray-freeze drying (SFD) technique was applied to sonicated aqueous suspensions of spray-dried montmorillonite clay (MMT) to produce highly porous agglomerates (SFD-MMT). Both MMT (used as a reference) and SFD-MMT were subsequently incorporated in polypropylene (PP) via melt compounding to produce 2 wt % nanocomposites with and without maleic anhydride grafted polypropylene (PP-g-MA). Polypropylene nanocomposites containing SFD-MMT exhibited thinner silicate flake layers compared to large agglomerates in PP/MMT nanocomposites. SFD-MMT particles became even more finer in the presence of PP-g-MA (i.e., in PP/PP-g-MA /SFD-MMT) where it hindered PP crystallization instead of serving as nucleation sites for the PP crystallization during rapid cooling. SFD-MMT improved the thermal stability of PP/PP-g-MA by 30°C compared to only 5–8°C for MMT/nanocomposites. MMT acts as a heterogeneous nucleating agent in the nucleation-controlled PP nanocomposites, but the hindrance effect was observed for the PP/PP-g-MA with SFD-MMT. PP/PP-g-MA/SFD-MMT exhibited twice the edge surface energy as compared to PP/PP-g-MA/MMT. The incorporation of both types of MMT raised the tensile moduli of PP and PP/PP-g-MA, with no improvement in their tensile strength and a decrease in the elongation at break. The PP/PP-g-MA/SFD-MMT showed brittle failure. POLYM. ENG. SCI., 60:168–179, 2020. © 2019 Society of Plastics Engineers     

纯烤烟(SVC)最新发展技术--第一部分

Part 1. Basic Principles This is the first article in a series of three that is based on Dr. Abdallah's presentation at China Tobacco Society Convention, December 11-13, 2003, in Shanghai. The series discusses the contributions of manufacturing in general, and blending and processing in particular, to the development of premium costeffective lower-tar SVC products with acceptable smoking qualities.     

Isolation and analysis of macromolecular fractions responsible for the surface properties in native Champagne wines

Macromolecules present in Champagne wines from the three grape varieties Pinot Noir, Meunier and Chardonnay, were isolated by ultra-concentration on 10 K molecular weight cut-off (MWCO) membranes, then purified by dia-filtration and freeze-dried. Measurements of the surface activity of reconstituted wines from the resulting dry ultra-concentrates by ellipsometry showed the formation of adsorption layers analogous to those observed at the surface of native wines, and responsible for their foam stability. Sequential fractionation of Pinot Noir at decreasing MWCO within the 10–30 K and 30–100 K molecular weight range showed the formation of adsorption layers with both fractions. NMR and chemical analysis indicated that all fractions were mainly composed of polysaccharides and proteins. Monosaccharide analysis gave mannose, galactose, arabinose and glucose as the prominent constituting sugars. Careful bottle rinsing was found to enable thorough macromolecule recovery.     

Synthesis,Biological Evaluation of 1,1‐Diarylethylenes as a Novel Class of Antimitotic Agents

The cytotoxic activities of 23 new isocombretastatin A derivatives with modifications on the B‐ring were investigated. Several compounds exhibited excellent antiproliferative activity at nanomolar concentrations against a panel of human cancer cell lines. Compounds isoFCA‐4 ( 2 e ), isoCA‐4 ( 2 k ) and isoNH₂CA‐4 ( 2 s ) were the most cytotoxic, and strongly inhibited tubulin polymerization with IC₅₀ values of 4, 2 and 1.5 μM , respectively. These derivatives were found to be 10‐fold more active than phenstatin and colchicine with respect to growth inhibition but displayed similar activities as tubulin polymerization inhibitors. In addition, cell cycle arrest in the G₂/M phase and subsequent apoptosis was observed in three cancer cell lines when treated with these compounds. The disruptive effect of 2 e , 2 k and 2 s on the vessel‐like structures formed by human umbilical vein endothelial cells (HUVEC) suggest that these compounds may act as vascular disrupting agents. Both compounds 2 k and 2 s have the potential for further prodrug modification and development as vascular disrupting agents for treatment of solid tumors.     

Microstructure and mechanical properties of AlN films obtained by plasma enhanced chemical vapor deposition

AlN films were prepared with a microwave plasma enhanced chemical vapor deposition reactor working at different process temperatures in order to obtain polycrystalline 〈0001〉 oriented films for piezoelectric applications. The films developed were characterized in terms of microstructure, composition, and mechanical properties. Crystalline development and a single orientation were obtained at high temperatures, where at the same time an increase in mechanical intrinsic stresses was observed. Well crystallized 〈0001〉 films were obtained at temperature as low as 500 °C. Furthermore, the evolution of microstructure with thickness at higher temperatures showed a single 〈0001〉 orientation with progressive increase of the texture as the thickness increased. This fact was related with changes in the observed microstructure along the film z-axis, evaluated by high resolution transmission electronic microscopy and selected area electron diffraction. Although orientation dispersion of these films, evidenced by the rocking curves FWHM, remained relatively high (>9°), they can be regarded as promising for piezoelectric applications. Annealing tests conducted at relatively high temperatures with films deposited at low temperature indicated that thermal effects have only a major effect during the film growth for the temperature values employed.     

Heritability of changes in genetic evaluations of dairy bulls from first to later records of daughters

Objectives of this study were to investigate changes in predicted transmitting abilities (PTA) of yields from evaluations based on first records to evaluations based on first and later records of daughters and determine whether these changes are heritable. Data were USDA sire evaluations of July 1989 through May 2000 on Holstein bulls in standard progeny testing programs. Changes in PTA for milk, fat, and protein from evaluations based on first records of daughters to evaluations on first and second were obtained on 2001 bulls. These were divided into two sets: subset 1 (n = 889) included bulls first evaluated before 1995 and subset 2 (n = 1112) included bulls first evaluated in 1995 and later. Changes in PTA from first-record evaluation to most recent evaluation (May 2000) were obtained on 2524 bulls first evaluated in 1995 or later. Mean changes in PTA for bulls first evaluated in 1995 and later were smaller than mean changes for bulls evaluated earlier but standard deviations were similar. Regressions of changes in PTA on changes in parent average showed that a change of 1.0 kg in parent average resulted in 1.1 to 1.2 kg change in PTA. Heritabilities estimated with animal model ranged from 0.14 to 0.23 for changes from first-record evaluation to evaluation on first and second, and 0.27 to 0.35 for changes from first-record evaluation to most recent evaluation. Heritabilities of this magnitude allow for identifying bulls that decrease in PTA.     

Bioequivalence of two brands of ciprofloxacin 750 mg tablets (Sarf and Ciprobay) in healthy human volunteers

An open, randomized, two-way crossover study was carried out in 28 healthy volunteers at Gulf Pharmaceutical Industries (Julphar), as a joint venture with Saqr Hospital, Ras Al-Khaimah, UAE. The two commercial brands used were Sarf (Julphar, UAE) as test and Ciprobay (Bayer AG, Germany) as reference product. The drug was administered to each subject with 240 mL of water after an overnight fasting in two treatment days separated by a one-week washout period. After dosing, serial blood samples were collected for a period of 24 hr and serum was separated and analyzed for ciprofloxacin using a sensitive, reproducible, and accurate high-performance liquid chromatography (HPLC) method with ultraviolet (UV) detection. Various pharmacokinetic parameters, including AUC0-t, AUC0-infinity, Cmax, Tmax, t1/2, and lambdaz, were determined from ciprofloxacin serum concentration-time profiles for both formulations and found to be in good agreement with reported values. The parameters AUC0-t, AUC0-infinity, and Cmax were tested for bioequivalence after log-transformation of data. No significant difference was found based on analysis of variance (ANOVA); the 90% confidence intervals (95.73-107.62%, 94.98-108.26%, 92.80-103.90% for AUC0-t, AUC0-infinity, Cmax, respectively) for the test/reference ratios of these parameters were within the bioequivalence acceptance range of 80-125%. Based on this data, it is concluded that both formulations are bioequivalent and are interchangeable in medical practice.