Parameters influencing the electrodeposition of a Ni-Cu coating on Fe powders. I. Effect of the electrolyte composition and current density

Electrochemical deposition of a two-component Ni-Cu coating onto Fe powder particles was studied by constant current electrolysis. The influence of the Ni(II) to Cu(II) salts ratio in the electrolyte, of the addition of sodium citrate as complexing agent to the electrolyte, and of the current density with respect to the total surface of compact and dispersed electrodes was studied. It was shown that the less noble Ni deposition is facilitated mainly by its large excess in the electrolyte and by an increase in current density. The addition of a complexing agent exhibits only a very slight influence on the coating composition but does suppress the spontaneous deposition of Cu. The current efficiencies of Ni, Cu and Ni-Cu deposition on the powder particles decrease with increasing sodium citrate concentration and current density.     

Synthesis,Crystal Structure and Electrochemical Behavior of a Fe(II) Complex of 8-Mercaptoquinoline (Hmtq) with Trimethylphosphite Participation

The mononuclear complex Fe(II)(mtq)₂{P(OCH₃)₃}₂ (Hmtq = 8-Mercaptoquinoline) with mixed N-heterocyclic thiolato and phosphite ligands was synthesized and characterized by X-ray crystallography and cyclic voltammetric measurement. The title complex crystallizes in the triclinic space group P-1 with a = 8.929(4), b = 9.965(3), c = 16.913(11) Å, α = 76.21(10), β = 80.89(10), γ= 68.010(10)°, V = 1351.2(11) ų. The Fe(II) atom exhibits an elongated octahedral geometry composed of N₂S₂P₂ donors. The equatorial plane is made up of two cis-oriented N donors from the thiolato ligands and two cis-oriented monodentate P(OCH₃)₃ ligands. The apical sites are occupied by two trans-oriented S atoms from the mtq^? ligands. The thione form is predominant coordination mode of 8-mercaptoquinoline with the N and S donors bound to the Fe(II) to form five-membered chelate rings. The structural feature of the mononuclear Fe(II) complex with mixed phosphite and thiolate ligands is summarized.     

Effect of the particle size and solids volume fraction on the thermal degradation behaviour of Invar 36 feedstocks

Degradation kinetics and the thermal stability of Invar 36 powder injection moulding feedstocks (PIM) based on cellulose acetate butyrate (CAB) and polyethylene glycol (PEG) binders were investigated using simultaneous thermogravimetric analysis (STA) and differential scanning calorimetry (DSC). The initial decomposition temperature (IDT) and the integral procedure decomposition temperature (IPDT) were used to analyse the thermal stability of the binder system as a function of the solid loading content and powder particle size. The degradation kinetics was studied, and the process apparent activation energies were assessed using isoconversional methods. All the methodologies revealed changes in the thermal degradation behaviours of the feedstocks for solid loadings that were previously determined to correspond to optimal solid loadings using other experimental procedures. The studies also contrast previous similar findings with a ceramic powder. Therefore these results strengthen the proposal of thermodynamic degradation studies of feedstocks as an alternative or complementary technique to determine optimal solid loading contents in metal injection moulding (MIM).     

Effect of ionic strength and ionic interactions on the oxidation of Fe(II)

The rates of oxidation of Fe(II) in NaCl and NaClO ₄ solutions were studied as a function of pH (6 to 9), temperature (5 to 25°C), and ionic strength (0 to 6m). The rates are second order with respect to [H⁺] or [OH^–] and independent of ionic strength and temperature. The overall rate of the oxidation is given by

Effect of grinding with hydroxypropyl cellulose on the dissolution and particle size of a poorly water-soluble drug.

A new benzofuroquinoline derivative, 3,9-bis(N,N-dimethylcarbamoyloxy)-5H-benzofuro[3,2-c]quinoli ne-6-one (KCA-098), shows poor oral absorption due to practical insolubility in water. In this study, a co-grinding technique employing a water-soluble polymer was used for improvement of the dissolution rate of KCA-098. Powder X-ray diffraction patterns and IR spectra of KCA-098 showed the conversion of the drug from a crystal state to an amorphous state by grinding with a polymer such as hydroxypropyl cellulose (HPC-SL) or polyvinylpyrrolidone (PVP K30). The particle size of KCA-098 was remarkably reduced to a submicron size by grinding with HPC-SL. The co-ground mixture with HPC-SL showed a rapid dissolution rate and maintained supersaturation for more than 1 h. On the other hand, the co-ground mixture with PVP K30 showed rapid dissolution and supersaturation for a shorter period. These data suggest that the rapid dissolution rate was obtained by the conversion of the drug particles from a crystal to amorphous state by grinding with water-soluble polymers and that a reduction in particle size to the submicron level led to the maintenance of supersaturation due to good dispersion.     

Effect of the pH on the complexation of Cu(II), Ni(II) and Fe(III) Ions by a vine leaf litter extract by fluorescence quenching

An extract of dead vine leaves (vitis viniferal) (VLE) was obtained by the extraction procedure for fulvic acids and its interaction (at a concentration of 25mg/L in 0.1 M KNO₃) with the Cu(II), Ni(II) and Fe(III) ions was studied in the pH range between 3 and 6. This interaction was monitored by synchronous molecular fluorescence, since bands due to the fluorescent ligands undergo quenching upon complex formation. After the chemometric isolation of the quenching profiles from the raw spectra by a self-modeling mixture analysis, SIMPLISMA, they were analyzed by two methods: (i) graphical procedures based on the Stern-Volmer model; and (ii) a non-linear least-squares procedure. For the Cu(II) and Ni(II) ions, the treatment by these two methods provided similar values both for the logarithm of the conditional stability constants (log Kc) and the percentage of fluorescent structures that do not participate in the complexation. The log Kc were (standard deviations in parenthesis): Cu(II) ion, 2.4 (3), 3.37(3), 4.4(1) and 4.92(9), respectively, for pH = 3, 4, 5 and 6; Ni(II)ion, 2.9(1), 3.3(2), and 4.09(3), respectively, for pH = 4, 5 and 6. For Fe(III) an interaction with VLE was observed, but no values for Kc could be obtained.     

Effect of temperature,particle size and percentage deacetylation on the adsorption of acid dyes on chitosan

The adsorption of five acidic dyes on chitosan—a by-product from waste crustacean shell—has been studied. The equilibrium data have been studied using Langmuir, Freundlich and Redlich-Peterson equations. The best correlations are obtained using the Langmuir isotherm suggesting the mechanism involves one process step of dyes complexing with the free amino group. The effect of chitosan particle size was investigated and showed an increase in adsorption capacity with decreasing particle size indicating that the available external surface was an important factor. Increasing solution temperature resulted in an increase in adsorption capacity indicating an exothermic process with a negative ΔH. Finally, the effect of varying the percentage degree of deacetylation showed that from 52% to 97% resulted in decrease in the dye adsorption capacity suggesting that more amorphisation may cause changes in the internal structure of chitosan and reduce the capacity.     

Effect of crystal form and particle size of titanium dioxide on the photodegradation behaviour of ethylene-vinyl acetate copolymer/low density polyethylene composite

The photodegradation behaviour of ethylene-vinyl acetate copolymer (EVA)/low density polyethylene (LDPE) composite containing four different types of titanium dioxide (TiO₂) was investigated through colour difference, Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and mechanical tests. The results showed that the performance losses of composites were qualitatively correlated with the degradation degree. The vinyl acetate (VA) groups in EVA were sensitive to UV light and the photodegradation mainly occurred in the amorphous region. The chain scission and annealing effect facilitated the secondary crystallization of composites. The heterogeneous nucleation effect of TiO₂ on the crystallization of composites was related to the particle size of TiO₂. The micro rutile TiO₂, micro anatase TiO₂ and their mixture (rutile/anatase = 13/87) exhibited a photo-stabilising effect, while the nano mixed crystals TiO₂ (rutile/anatase = 20/80) had an opposite effect.     

75例3岁以下营养不良儿血铅,锌,铜,铁,钙含量的变化

比较了７５例３岁以下营养不良儿与正常儿的全血铅、锌、铜、铁、钙含量，结果发现营养不良儿以上５种元素均较正常儿明显减少，经统计学处理有非常显著意义（Ｐ＜０．０１）．提示这５种元素与营养不良密切相关。Ⅲ度营养不良儿的血锌、铜、铁、钙含量又比Ⅰ、Ⅱ度营养不良儿明显降低．本组血铅含量虽然比本地区正常儿降低，但已高于国外内诊断标准，提示营养不良对铅的吸收可能较正常儿低，但对铅中毒易感性增高，也可能是营养不良生长发育障碍的原因之一。在治疗营养不良同时补充微量元素锌、铁、钙可以减少铅的吸收。     

Effect of synthesis parameters on the particle size, composition and colloid stability of polypyrrole–silica nanocomposite particles

 The effect of varying the oxidant, monomer and silica sol concentrations, silica sol diameter, polymerization temperature, stirring rate and oxidant type, on the particle size, polypyrrole content and conductivity of the resulting polypyrrole– silica colloidal nanocomposites has been studied. Surprisingly, nanocomposite formation appears to be relatively insensitive to most of the above synthesis parameters. One synthesis parameter which does have a significant and reproducible effect is the stirring rate: smaller, more monodisperse nanocomposite particles are obtained from rapidly stirred reaction solutions. However, this effect is only observed for the (NH₄)₂S₂O₈ oxidant. An alternative oxidant, H₂O₂/Fe³⁺, was found to give nanocomposites of similar particle size, polypyrrole content and conductivity to those obtained using the (NH₄)₂S₂O₈ oxidant. The colloid stability of these polypyrrole–silica nanocomposite particles depends on their silica content. The colloid stability of a silica-rich nanocomposite prepared using the (NH₄)₂S₂O₈ oxidant in the presence of electrolyte was comparable to that of a silica sol, whereas a polypyrrole-rich nanocomposite prepared using FeCl₃ had markedly poorer colloid stability under these conditions. These observations are consistent with a charge stabilization mechanism for these nanocomposite particles. Received: 5 March 1998 Accepted: 27 April 1998     

Effect of solvent on the construction of Co(II) coordination polymers containing a semi-rigid bis(benzimidazole) derivative: syntheses,structures, and properties

Two Co(II) coordination polymers, [CoL(npa)]·2H₂O (1) and [CoL(Hnpa)₂] (2) (L = 1,4-bis(5,6-dimethylbenzimidazole-1-yl)benzene, H₂npa = 5-nitroisophthalic acid), have been synthesized in different solvent systems and characterized by Infrared (IR) spectroscopy, elemental analysis, and powder and single crystal X-ray diffraction. Compound 1 was synthesized under solvothermal conditions with DMF as solvent and had a pair of L ligands adopting a μ₂-bridging mode and connecting two Co²⁺ cations to generate a 26-membered Co₂L₂ loop. The npa^2? link adjacent Co₂L₂ loops via a bis(monodentate) bridging mode to create a 1-D channel-like chain structure. Compound 2 was obtained under hydrothermal conditions, and the carboxylate of the monodeprotonated Hnpa^? adopt a μ₁-η^0?:?η¹ coordination to connect adjacent Co²⁺ cations into a 2-D polymeric layer. The μ₂-bridging L ligands connect adjacent 2-D [Co(Hnpa)]_n polymeric layers into a 3-D NaCl-like framework. The Co²⁺ cations and the L ligands in compounds 1 and 2 exhibit different coordination geometries and conformations. Effects of solvents on the construction of Co(II) coordination polymers were investigated. In addition, the electrochemical behavior of carbon paste electrodes containing 1 and 2 and the thermal stabilities of 1 and 2 were investigated.     

Effect of different molecular weights of polyethylene glycol as a plasticizer on the formulation of dry powder inhaler capsules: Investigation of puncturing size,morphologies, and surface properties

Today, the principle of research and development is pulmonary drug delivery due to the potential for maximizing therapeutic effects for patients by direct drug targeting the pathology site in the lungs. Amongst the convenient delivery alternatives, the Dry Powder Inhaler (DPI) is the preferred device to remedy a variety of diseases. In this regard, the fabrication and development of a novel formulation for DPI capsules have been studied. We investigated the effects of various parameters, such as percentages of polyethylene glycol (PEG), propylene glycol (PG), glycerol (Gly), brittleness, test conditions, and particle release of manufactured DPI capsules. The efficacy of each parameter was evaluated in detail to understand and address the consequences of the mentioned factors. The results illustrated that the lower molecular weight of PEGs presented the better plasticizing capability of gelatin. Owing to the hygroscopicity of the utilized plasticizer, polyethylene glycol 400 (PEG 400) increased the capsule flexibility for a longer time and its stability under environmental conditions in the gelatin capsule formulation. Likewise, no particle release was observed in the gelatin/PEG capsule. The prepared gelatin/PEG400 capsules were compared with pure gelatin and HPMC capsules. The capsules were evaluated in terms of loss on drying (LOD), surface morphology, roughness, and puncture type. The results show that using PEG-400 can lead to the production of capsules that have low moisture content and minimal interaction with APIs. In addition, gelatin/PEG capsules have no particles due to the smooth surface after the punching process. The as-produced capsules are not blocked again after punching, allowing the patient to take the drug completely. In fact, the present research provided substantial insight regarding the development of DPI formulation in capsule investigations on an industrial scale.     

Effect of adsorption site, size, and composition of Pt/Au bimetallic clusters on the CO frequency: a density functional theory study

Density functional theory (DFT) calculations were performed to investigate the C-O stretching frequency changes when a CO molecule was adsorbed to Pt/Au clusters of 2-4 atoms. Our calculations show that the adsorption site is the most sensitive quantity to the C-O stretching frequency shifts. All the bridge site adsorptions yield a CO frequency band of 1737-1927 cm-1 with the CO bond distance of 1.167-1.204 A regardless of cluster composition and size, and all the atop site adsorptions yield a CO frequency band of 2000-2091 cm-1 with the CO bond distance of 1.151-1.167 A. More detailed analysis of the two frequency bands shows that each band may consist of two emerging subbands with the lower frequencies corresponding to the CO adsorption to Pt atoms and the higher frequencies to the CO adsorption to Au atoms. The insensitivity of the CO frequency shift to the cluster size indicates that the trend discussed here for small clusters may be used to interpret the experimental observations for nanoparticles. Our results also illustrated that the Fourier transform infrared spectroscopy measurement may be used as a sensitive tool to identify adsorption sites of the Pt/Au nanoparticles using CO adsorption as the probe.     

Synthesis,crystal structure and magnetic properties of a new tri‐nuclear iron (II,III) complex,a precursor for the preparation of superparamagnetic Fe3O4 nanoparticles applicable in the removal of Cd2+

This study reports the structural and spectroscopic characterization of a novel metal organic compound formulated as [Fe (bpy)₃] [Fe (dipic)₂]₂.7H₂O ( 1 ) (dipic = pyridine‐2,6‐dicarboxylate and bpy = 2,2^′‐bipyridine). 1 was investigated by elemental analysis, FT‐IR spectroscopy, powder X‐ray diffraction and single crystal X‐ray diffraction (SC‐XRD), which revealed a triclinic structure of expected composition. Thermal degradation of 1 was also investigated. Complex 1 was used as a precursor to prepare superparamagnetic nanoparticles of Fe₃O₄ by thermal analysis. The obtained Fe₃O₄ was characterized by Fourier transformed infrared spectroscopy (FT‐IR), powder X‐ray diffraction (XRD) and scanning electron microscopy (SEM). Fe₃O₄ nanoparticles were used as a nano‐adsorbent to remove Cd²⁺ from water at room temperature. The results showed that this nano‐adsorbent is effective in removing Cd²⁺ from contaminated water sources, and that the maximal effectivity of adsorption occurs at pH = 6. Magnetic measurements of complex 1 and Fe₃O₄ nanoparticles at room temperature revealed paramagnetic and superparamagnetic behavior, respectively.     

Experimental investigation of the effect of initial fuel particle shape, size and bed temperature on devolatilization of single wood particle in a hot fluidized bed

Considerable amount of investigation on the subject of devolatilization of wood is found in the open literature. However, a systematic study of the effect of initial particle size and shape, and bed temperature on devolatilization time and char yield of wood in a hot fluidized bed is still missing. This paper attempts to fill this gap through a systematic experimental investigation to determine the devolatilization time and char yield of a typical woody biomass, “Casuarina equisetifolia” particles of different initial sizes and shapes at various fluidized bed temperatures. Experiments are conducted using 10, 15, 20, and 25 mm Casuarina wood particles of three shapes, namely, cube, cylinder, and sphere at bed temperatures of 1023, 1123, and 1223 K.It is found that the initial wood particle size has the strongest influence on devolatilization time followed by the shape of initial wood particle and the bed temperature. Correlation for devolatilization time (τ_d) as a function of initial wood particle size (d_eq), sphericity (?), and bed temperature (T_b), is developed using 573 experimental data points exhibiting a correlation coefficient of 0.96 and predictions falling well within a deviation band of ±20%. The predictions of the present correlation are compared with the predictions of the existing correlations in literature for conditions also out of the present study and the deviation is found to be ±30%.Char yield, defined as the ratio of the residual mass at the end of devolatilization process to the initial mass of the wood particle is found to be in the range of 9-14% for all sizes, shapes, and bed temperatures. Char yield does not depict any definite trend with the variation of initial particle size, shape and bed temperature.     

Effect of the cell type and cell density on the binding of living cells to a silica particle: an atomic force microscope study

We used the atomic force microscope to study how the cell type and the density of cells adsorbed at a substrate can affect the adhesion between a living cell and a model drug delivery system (DDS) carrier nano-particle. We used three different anchorage-dependent cells, i.e., a living mouse fibroblast cell (L929), a living human colon cancer cell (Caco2), and a living mouse malignant melanoma cell (B16F10). For the DDS model nano-particle, we used a silica colloid. In order to correlate the adhesion force with the cell types, the growth curve of the cells were determined with a haemocytometer. The shapes of the cells at the different stages were monitored by light microscopy, and the morphology of their surfaces obtained by tapping mode atomic force microscopy.

Force measurements showed that the Caco2 cell bound little to a silica particle, regardless of the cell density. The L929 cell bound well to a silica particle for low and high cell densities. The B16F10 cell bound little to a silica particle for low cell densities, but bound well for high cell densities. AFM images showed that the L929 cell did not contain folds. The B16F10 cells, however, displayed folds in the cell surface for low cell densities, but no folds in the cell for high cell densities. As literature also reported that the Caco2 cell contains folds, these results suggested that cells with folds showed less adhesion to a silica particle than cells without folds. The presence of folds in the cell presumably decreased the number of sites on the cell that could hydrogen bond or undergo van der Waals binding with the silanol groups of the silica particle.     

Fe(HSO4)3: An efficient, heterogeneous and reusable catalyst for the synthesis of 14-aryl- or alkyi-14H-dibenzo[a.j]xanthenes

Fe(HSO4)3 has been used as an efficient and reeyclable catalyst for the one-pot synthesis of 14-aryl- or alkyl-14H-dibenzo[a,j]xanthene derivatives by the reaction of 2-naphtol and aldehydes. Different types of aromatic and aliphatic aldehydes are used in the reaction and in all cases the products were obtained in good to excellent yields.     

Effect of the reaction parameters on the particle size in the dispersion polymerization of 2‐hydroxyethyl and glycidyl methacrylate in the presence of a ferrofluid

The precipitation of Fe₃O₄ from an aqueous solution with ammonium hydroxide produced nanoparticles that were coated with a layer of oleic acid [or, in some cases, poly(ethylene oxide) or poly(vinylpyrrolidone)] before their dispersion into the organic phase. The encapsulation of magnetite nanoparticles in poly(2‐hydroxyethyl methacrylate) or poly(2‐hydroxyethyl methacrylate‐co‐glycidyl methacrylate) microparticles was achieved by dispersion polymerization in toluene/2‐methylpropan‐1‐ol. Magnetic poly(glycidyl methacrylate) microparticles were obtained in the presence of poly(ethylene oxide) at the magnetite/monomer interface. The particles containing up to 20 wt % iron maintained their discrete nature and did not aggregate. The effect of the reaction medium polarity, the concentrations of the monomer, initiator, and stabilizer, and the temperature on the particle size, particle size distribution, and iron and oxirane group contents was studied. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1848–1863, 2003     

Poly(N-isopropylacrylamide). II. Effect of polymer concentration,temperature, and surfactant on the viscosity of aqueous solutions

The effects of polymer concentration, temperature, and surfactant on the rheological properties of poly(N-isopropylacrylamide), poly NIPAM, were studied. Below 28°C the viscosity decreased with increasing temperature according to the Arrhenius expression. However, at 29°C the viscosity increased to a maximum value at 32°C, the lower critical solution temperature (LCST) for aqueous polyNIPAM. Higher temperatures gave a much lower viscosity. This unusual rheological behavior was explained by the phase behavior of the polymer. Sodium dodecyl sulfate (SDS) binding to polyNIPAM increased the cloud point temperature (CPT) and attenuated the unusual rheological behavior of polyNIPAM in water. © 1993 John Wiley & Sons, Inc.