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Ni2+ and Cu2+ are the major heavy metal ions in electroplating wastewater of Hong Kong. In the present study, Pseudomonas putida 5-x cell biomass was used to remove Ni2+ from electroplating effluent. Ni2+ adsorption capacity of P. putida 5-x cell biomass cultured in sulphate-limiting medium was found to be minimum in early logarithmic growth phase, and maximum of 28.1 mg g(-1) in late stationary growth phase. Pretreated cells by 0.1 mol L(-1) HCl could greatly enhance the Ni2+ adsorption capacity of cell biomass from 28.1 to 36.7 mg g(-1) and had no significant effect on biomass loss. The adsorption process of P. putida 5-x fresh cells and pretreated cell all could be expressed with Freundlich isotherm. TEM analyses indicated that acidic pretreatment degraded the superficial layer-capsule outside of the fresh cell to improve the adsorption capacity of cell to Ni2+. The Ni2+ bound by P. putida 5-x cell biomass could be efficiently recovered using 0.1 mol L(-1) HCl, and the cell biomass could be reused at least five cycles for Ni2+ removal and recovery with 93% above removal efficiency and 98% above recovery rate. Owing to the Cu2+ presented in electroplating wastewater inhibiting Ni2+ adsorption process by P. putida 5-x cell biomass, two-stage biosorption processes should be designed to remove and recover Cu2+ and Ni2+ sequentially from electroplating effluent.
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PMID:Ni2+ removal and recovery from electroplating effluent by Pseudomonas putida 5-x cell biomass. 1268 May 80

The extraction behavior and phase behavior of TOPO (or TRPO)-kerosene/HCl-ZrOCl(2) systems have been investigated. The middle phase with bicontinuous structure is first used as both the Zr(IV) source and the template to prepare mesoporous material just by precipitation with aqua ammonia under low temperature. By this method, crystal mesoporous ZrO(2) powders with average d-values of 6.3 and 7.48 nm, respectively, have been obtained. TG-DTA, TEM, and XRD are adopted for the characterization of the synthesized sample.
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PMID:Preparation of mesoporous ZrO2 with the middle phase formed in a trioctyl (or alkyl) phosphinic oxide-kerosene/HCl-ZrOCl2 extraction system. 1292 70

Use of a dialkoxysilane-containing, condensable alanine amphiphile with a cleavable hexadecyl ester tail (1) as a "lizard" template for sol-gel synthesis results in the formation of a mesoporous silicate (2) whose channels are filled with an organic group of the template. Treatment of 2 with aqueous HCl allows selective cleavage of the ester moiety to leave nanochannels (3) whose surface is densely covered with alanine-CO2H. According to XRD and TEM, 2, on conversion into 3, can preserve its regular hexagonal structure. 3 displays a clear N2 adsorption/desorption isotherm with a BET surface area of 536 m2 g-1. 3 can also adsorb a basic guest such as NH3 up to 0.7 mmol g-1, which is 7 times greater than that observed for mesoporous silica obtained by calcination of 2.
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PMID:A condensable amphiphile with a cleavable tail as a "Lizard" template for the sol-gel synthesis of functionalized mesoporous silica. 1474 44

Natural bentonite spent in the process of plant oil bleaching was used as an initial material for preparation of carbon-mineral adsorbents. The spent bleaching earth was treated using four procedures: T (thermal treatment); H (hydrothermal treatment); C (thermal treatment with addition of CCl4 vapor); M (modification of porous structure). Raw bentonite, RB (raw bleaching earth), and carbon materials prepared using plant oil were compared. The physicochemical characteristics of the adsorbents were determined using different methods: nitrogen adsorption/desorption, XRD, TEM, and MS-TPD. Carbon-mineral adsorbents contain from 5.23 to 19.92% C (w/w) and carbon adsorbents include from 84.2 to 91.18% C (w/w). Parallel processes of organic substance carbonization, porous structure modification, sublimation or evaporation of metal chlorides, and removal of hydrogen chloride take place during pyrolysis of waste mineral materials in the CCl4 atmosphere.
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PMID:Carbon-mineral adsorbents prepared by pyrolysis of waste materials in the presence of tetrachloromethane. 1575 82

The purpose of this study was to investigate the nasal absorption characteristics of a series of anti-allergic drugs across the human nasal epithelial cell monolayer, which was passage cultured by the liquid-covered culture (LCC) method on Transwell. Characterization of this cell culture model was achieved by bioelectric measurements and morphological studies. The passages 2--4 of cell monolayers exhibited the TEER value of 1731+/-635 Omega cm(2) after 2 days of seeding and maintained high TEER value for 4--6 days. Morphological study by TEM and SEM showed the existence of the tight junctions, and the cuboidal shaped epithelial cells monolayer. A series of anti-allergic drugs, albuterol hemisulfate, albuterol, fexofenadine HCl, dexamethasone, triamcinolon acetonide, and budesonide were selected as model compounds for transport studies. All the drugs were assayed using reversed-phase HPLC under isocratic conditions. Results indicated that within the logP (apparent 1-octanol/water partition coefficient) range from --1.58 (albuterol) to 3.21 (budesonide), there existed 100-fold difference in the apparent permeability coefficients (P(app)). A log-linear relationship was shown between the drug logP and the P(app) across passaged human nasal epithelial monolayers. The amount of fexofenadine HCl and dexamethasone across passaged human nasal cell monolayers was concentration-dependent in the direction of apical to basolateral. The direction dependent transport studies were investigated among all these drugs and no significant difference in the two directions was observed. In conclusion, this LCC passaged human nasal epithelial culture model may be a useful in vitro model for studying the passive transport processes in nasal drug delivery.
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PMID:Transport of anti-allergic drugs across the passage cultured human nasal epithelial cell monolayer. 1608 22

The purpose of this work was to investigate the physical properties of drug-loaded poly(methacrylic acid-g-ethylene glycol) {P(MAA-g-EG)} particles, their biocompatibility with the gastrointestinal tract of rats and also the effects of these particles on the tight junctions of the rat intestinal epithelium. Model drugs such as diltiazem HCl, diclofenac Na, ciprofloxacin HCl and isoniazid were used in this study. P(MAA-g-EG) particles were prepared by free radical solution polymerization of methacrylic acid (MAA) and poly(ethylene glycol) (PEG). The loading efficiency of the model drugs in the particles and in vitro release profiles were investigated in pH 7.4 phosphate buffer and in gradually pH changing buffers (pH 1.2, 5.8, 6.8 and 7.4). The stability of free particles and drug-loaded particles was established by Fourier transform infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC). In conclusion, P(MAA-g-EG) particles controlled the release rate of small molecular weight model drugs according to the pH of the medium. Stability of those particles loaded with drugs did not change in accelerated stability conditions. Histopathological results indicated that loading drugs to the particles prevented cell and tissue damage after 20 h. Free particles showed no change of tight junctions after 2 and 10 h. The results of TEM showed that increasing the amount of P(MAA-g-EG) particles from 100 to 385 mg clearly opened the tight junction, but with serious epithelial cell disruption.
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PMID:Release behaviour and biocompatibility of drug-loaded pH sensitive particles. 1642 23

The evolution of the solution microstructures during the formation of the hexagonal mesoporous material SBA-15 was studied by direct imaging and freeze-fracture replication cryo-TEM. A reaction mixture was sampled at different times after the addition of tetramethoxyorthosilane (TMOS) to an acidic solution of Pluronic P123 held at 50 degrees C. Solution microstructures were detected by direct imaging cryo-TEM in the time window of 6.5-40 min after the addition of the TMOS (t = 0). The micrographs revealed that the initial spheroidal micelles evolve into threadlike micelles, which become longer and straighter with time. Then bundles with the dimensions similar to those found in the final material appeared, although there was no sign of a hexagonal arrangement up to 40 min. Due to the appearance of a precipitate at 40 min the sample became too viscous, preventing clear observation of its content. To observe the structures present after 40 min, freeze-fracture replication was carried out as well. Such samples were collected also at 22 min and showed the presence of threadlike micelles in agreement with the direct imaging cryo-TEM micrographs. The 2 h samples showed some areas of hexagonal ordered structures, which become very clear at 2 h 50 min. The cryo-TEM measurements were carried out under the same reaction conditions used in earlier in situ EPR experiments, thus allowing us to correlate molecular level events with the microstructure shape evolutions. This showed that the elongation of the micelles is a consequence of a reduction of the polarity and the water content within the micelles due to silicate adsorption and polymerization. Similar experiments were carried out also on SBA-15 prepared with HCl and TMOS at 35 degrees C. The appearance of threadlike micelles, followed by clustering of the TLMs, was observed under these conditions as well, but the reaction rate was faster. This suggests that the observed mechanism for the formation of SBA-15 is general.
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PMID:Resolving intermediate solution structures during the formation of mesoporous SBA-15. 1652 18

A double-tail amine oxide surfactant, di-n-decylmethylamine oxide (2C10MAO), was prepared, and the effects of protonation on aggregate structure were examined by small-angle neutron scattering (SANS), cryo-transmission electron microscopy (cryo-TEM), turbidity, electric conductivity, and solubilization of an oil-soluble dye at various degrees of neutralization, X, defined as the mole ratio of HCl/2C10MAO. The surfactant makes an L(2) phase in the nonprotonated state (X = 0) in water. The L(2) phase is in equilibrium with an aqueous L(1) phase. On protonation, unilamellar vesicles (ULVs) are formed over a wide range of compositions (0.05 < X< 0.4-0.5 at C = 10 mM) as observed by cryo-TEM. At X = 0.2, the ULV is stable over a wide concentration range (3 mM < or = C < 0.1 M), but an L(alpha) phase replaces the vesicle phase at C > 0.1 M. SANS results show that the mean radius of the ULV is about 25 nm and the bilayer thickness is about 2 nm, consistent with the extended configuration of the alkyl chains of the surfactant. An important contribution to the enhanced stability of the bilayer structures over the L(2) phase is suggested to be the translational entropy of the counterions. The enhanced stability of the bilayers diminishes as the counterion concentration increases either by an increase of X or by the addition of a salt. When the counterion concentration exceeds a critical value, the ULV solutions transform into the L(2) phase (or L(2)/L(1) two-phase system at low surfactant concentrations). The critical composition X is about 0.4-0.5 in water, but it is below 0.4 in D(2)O. The critical NaCl concentration is below 5 mM at X = 0.2. The stability of ULVs against multilamellar vesicles is ascribed partly to undulation forces and partly to the adjustable nature of the spontaneous curvature of amine oxide monolayers. The characteristics of the ULV of the surfactant remain the same within a temperature range 25-50 degrees C at X = 0.2. An iridescent lamellar phase and possibly an L(3) phase were observed in a very narrow X range (0 < X < 0.02) prior to the vesicle phase.
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PMID:Charge-induced unilamellar vesicle formation and phase separation in solutions of Di-n-decylmethylamine oxide. 1670 80

Surface-modified gold nanoparticles have pronounced benefits in the biomedical field due to their significant interaction with delivery materials. In the present study we used hydrophobically-modified polycations (i.e., N-acylated chitosan) to stabilize gold nanoparticles. Aliphatic hydrophobic groups, having carbon chains of different lengths, were first grafted onto the backbone of chitosan by N-acylation with fatty-acid chlorides in order to increase its hydrophobicity. Gold nanoparticles stabilized with native chitosan and N-acylated chitosan were prepared by the graft-onto approach. Chemical modification and its quantification were studied by Fourier-transform infrared (FT-IR) spectroscopy. Further, the stabilized gold nanoparticles were characterized by different physico-chemical techniques such as UV-Vis, FT-IR, TEM, TGA and DLS. Spectral studies of gold nanoparticles show the backbone and the side chain functional groups of chitosan were not cleaved during the conjugation process. TEM observations revealed that the modified chitosan gold nanoparticles were well dispersed and spherical in shape with average size around 10-12 nm in triply-distilled water at pH 7.4, whereas the native chitosan gold nanoparticles appeared as clusters with 9.9 nm as average diameter and were dispersed only in dilute HCl. The size of modified chitosan gold nanoparticles varied depending on the length of grafting molecules.
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PMID:Stabilization of gold nanoparticles by hydrophobically-modified polycations. 1680 Jan 56

Acidic surfactants, single- and bi-2-methylheptanol polyethenoxy ether phosphate esters, H2PO3(OCH2CH2)nOCH2CH2CH2CH2CH2CH(CH3)2 (u-MHPEPE) and HPO3[(OCH2CH2)nOCH2CH2CH2CH2CH2CH(CH3)2]2 (d-MHPEPE), where n approximately 4, were synthesized. Phase behavior of u- and d-MHPEPE (u- and d-MHPEPE mixtures were abbreviated as MHPEPE) mixtures in aqueous solutions and vesicle formation were determined. Surface tension measurements showed that u-MHPEPE and MHPEPE have low surface tensions at critical micelle concentrations. gamma(cmc)=29.0 mNm(-1) and cmc=16.0 mmolL(-1) for u-MHPEPE, MHPEPE has two transition points suggesting the mixtures of u- and d-MHPEPE with gamma(cmc1)=30.5 mNm(-1) and cmc1=4.0 mmolL(-1), and gamma(cmc2)=27.3 mNm(-1) and cmc2=42.0 mmolL(-1). These values, specific gamma(cmc), are much lower than those of traditionally cationic or anionic surfactants such as cetyltrimethylammonium bromide (CTAB, gamma(cmc)=37.1 mNm(-1) at cmc=0.92 mmolL(-1)) and sodium dodecyl sulfate (SDS, gamma(cmc)=39.0 mNm(-1) at cmc=8.1 mmolL(-1)). Rich phase behavior was observed with increasing MHPEPE concentration, an isotropic L(1)-phase (micelle solution), an unstable emulsion-region (with time, the samples separate into two-phase), a transparently bluish and birefringent Lalpha-phase up to 200 mmol L(-1) with unilamellar and multilamellar vesicles. These unilamellar and multilamellar vesicles were demonstrated by using staining transmission electron microscopy (staining-TEM), which were compared to freeze-fracture TEM (FF-TEM). The vesicle-phase is stable for at least 1 year. Vesicle formation possibly could be explained in harmonization of the hydrophobic force of acidic surfactant tails, the hydrogen bonding (H-bonding) and the electrostatic interaction among polar headgroups of PEO ether phosphate ester. Phase transition from the flow birefringent unilamellar vesicles induced by addition of HCl, NaCl, NaOH, and increasing temperature has been observed. Surprisingly, for u-MHPEPE or d-MHPEPE in water, we just observed L1-phase (micelle solution) with increasing u-MHPEPE or d-MHPEPE concentration.
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PMID:A promising system of mixed single- and double-short-tailed PEO ether phosphate esters: phase behavior and vesicle formation. 1688 36


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