Glycerol effects on the formation and rheology of cubic phase and related gel emulsion

We have investigated the effects of glycerol on the formation and rheological behavior of cubic phase (I(1)) and related O/I(1) gel emulsion in a water/C(12)EO(8)/dodecane system at 25 degrees C. The phase behavior of the water/C(12)EO(8)/dodecane system was studied by optical observation and structures of different liquid crystalline phases were identified by small-angle X-ray scattering (SAXS) techniques. Addition of dodecane (2 wt%) to aqueous solutions of C(12)EO(8) in a concentrated region (40 wt%) leads to the formation of the I(1) phase (which was absent without the addition of oil). The I(1) phase solubilized some amount of oil and at higher oil concentrations the I(1)+O phase was formed, allowing the preparation of O/I(1) gel emulsion. Rheological measurements have shown that the complex viscosity, |eta( *)|, of the I(1) phase is tremendously high ( approximately 10(7) Pas) and it increases with increasing oil concentration, attains a maximum value near the phase boundary, and then decreases drastically in the I(1)+O region. The increasing |eta( *)| or decreasing tandelta(G(')/G(')) can be ascribed with the interactions among the neighboring micelles. The decreasing trend of the |eta( *)| in the I(1)+O region is simply due to the low volume fraction of the I(1) phase. It has been shown that glycerol decreases the viscosity of the I(1) phase and related gel emulsion, which is due to the I(1)-hexagonal phase (H(1)) microstructural transition. Digital images show the physical appearance of the emulsion, which depends on the glycerol concentration changes from translucent to transparent.     

Micellization and Clouding Phenomenon of Phenothiazine Drug Promethazine Hydrochloride: Effect of NaCl and Urea Addition

Herein we report the micellization and clouding behavior of promethazine hydrochloride (PMT) in absence and presence of NaCl/ureas. The critical micelle concentration (CMC) of PMT is measured by conductivity method and the values decrease with increasing the NaCl concentration. With increasing the temperature, the CMC first increases then decreases. At 25°C, the maximum CMC values were obtained (with or without NaCl). The thermodynamic parameters are evaluated which indicate more stability of the PMT solution in presence of NaCl. PMT shows phase separation also. The cloud point (CP) of PMT decreases with increase in pH due to deprotonation of the drug molecules. Ureas decreased the CP and the behavior is explained on the basis of removal of water from the head group region.     

Synthesis and Characterization of Organosilicon Substituted Fluorenyl Derivatives

Friedel‐Crafts cycloalkylation of biphenyl with 2,3‐dichlorobutyltrichlorosilane(Cl₃Si‐CH₂CHClCHClCH₃) at a temperature of 100°C in the presence of anhydrous aluminum chloride catalyst gave cyclized product, 9‐methyl‐9‐(2‐trichlorosilylethyl)fluorene 1a , in 33% yield. Methylation of 1a with nucleophilic reagent such as methyl magnesium chloride, gave 9‐methyl‐9‐(2‐trimethylsilylethyl)fluorene 2 while bromination of 2 with excess amount of bromine in DMF resulted in 2,7‐dibromo‐9‐methyl‐9‐(2‐trichlorosilyl)fluorene 3 in good yield. All the compounds were structurally identified by GC/MS, ¹H and ¹³C‐NMR spectroscopy.     

Preparation of chitosan–polyethylene glycol coated cotton membranes for wound dressings: preparation and characterization

Cotton fabric was coated with chitosan (CS) and polyethylene glycol (PEG) followed by freeze‐drying. The influence of PEG on the physical characteristics and the surface morphology was investigated. The scanning electron microscopy of the coated fabric revealed a porous structure. The porosity of the material was 54–70% and the pore size was in the range of 75–120µm. The increase in the PEG content in the blend composition led to an enhanced destabilization of pores, leading to an increase in the pore size with elongated morphology. There seems to be phase separation between the two components which is an important factor for the observed behavior of the porous structure. The Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) showed that the CS and PEG have limited interaction. DSC suggested that addition of PEG to CS does not interfere with the crystallization behavior due to limited interaction with CS. The thermogravimetric analysis (TGA) showed that the membranes are thermally stable and PEG enhances the thermal stability of the CS coated membranes. The air and water permeability of the membranes tended to decrease with the increase in the PEG content. Copyright © 2008 John Wiley & Sons, Ltd.     

Application of microbioreactors in fermentation process development: a review

Biotechnology process development involves strain testing and improvement steps aimed at increasing yields and productivity. This necessitates the high-throughput screening of many potential strain candidates, a task currently mainly performed in shake flasks or microtiter plates. However, these methods have some drawbacks, such as the low data density (usually only end-point measurements) and the lack of control over cultivation conditions in standard shake flasks. Microbioreactors can offer the flexibility and controllability of bench-scale reactors and thus deliver results that are more comparable to large-scale fermentations, but with the additional advantages of small size, availability of online cultivation data and the potential for automation. Current microbioreactor technology is analyzed in this review paper, focusing on its industrial applicability, and directions for future research are presented.     

Photodegradation of the pharmaceuticals amoxicillin, bezafibrate and paracetamol by the photo-Fenton process—Application to sewage treatment plant effluent

Photodegradation of the pharmaceuticals amoxicillin (AMX), bezafibrate (BZF) and paracetamol (PCT) in aqueous solutions via the photo-Fenton process was investigated under black-light and solar irradiation. The influences of iron source, initial H₂O₂ concentration and matrix (distilled water and sewage treatment plant effluent) on degradation efficiency were discussed in detail. The results showed that (i) the degradation of the drugs was favored in the presence of potassium ferrioxalate (FeOx) in comparison to Fe(NO₃)₃; (ii) the increase of the H₂O₂ concentration improved the efficiency of AMX and BZF oxidation; however, the same was not observed for PCT; (iii) the influence of the matrix was observed for the degradation of BZF and PCT; (iv) under solar irradiation, the oxidation of the BZF and PCT is faster than under black-light irradiation. All these pharmaceuticals can be efficiently degraded employing the process evaluated.     

Synthesis and reactions of benzopentathiepin having hydroxyl group

The synthesis of benzopentathiepin having a hydroxyl group at the neighboring position of polysulfur ring was performed by demethylation of 6-ethyl-9-methoxybenzopentathiepin with hydrogenbromide. Benzotrithiole having hydroxyl group was not isolated at all. The hydroxyl group was also alkylated with alkyl iodide in the presence of weak base.     

Structural characterization of methanol substituted lanthanum halides

The first study into the alcohol solvation of lanthanum halide [LaX₃] derivatives as a means to lower the processing temperature for the production of the LaBr₃ scintillators was undertaken using methanol (MeOH). Initially the de-hydration of {[La(μ-Br)(H₂O)₇](Br)₂}₂ (1) was investigated through the simple room temperature dissolution of 1 in MeOH. The mixed solvate monomeric [La(H₂O)₇(MeOH)₂](Br)₃ (2) compound was isolated where the La metal center retains its original 9-coordination through the binding of two additional MeOH solvents but necessitates the transfer of the innersphere Br to the outersphere. In an attempt to in situ dry the reaction mixture of 1 in MeOH over CaH₂, crystals of [Ca(MeOH)₆](Br)₂ (3) were isolated. Compound 1 dissolved in MeOH at reflux temperatures led to the isolation of an unusual arrangement identified as the salt derivative {[LaBr_2.75·5.25(MeOH)]^+0.25 [LaBr_3.25·4.75(MeOH)]^−0.25} (4). The fully substituted species was ultimately isolated through the dissolution of dried LaBr₃ in MeOH forming the 8-coordinated [LaBr₃(MeOH)₅] (5) complex. It was determined that the concentration of the crystallization solution directed the structure isolated (4 concentrated; 5 dilute) The other LaX₃ derivatives were isolated as [(MeOH)₄(Cl)₂La(μ-Cl)]₂ (6) and [La(MeOH)₉](I)₃·MeOH (7). Beryllium Dome XRD analysis indicated that the bulk material for 5 appear to have multiple solvated species, 6 is consistent with the single crystal, and 7 was too broad to elucidate structural aspects. Multinuclear NMR (¹³⁹La) indicated that these compounds do not retain their structure in MeOD. TGA/DTA data revealed that the de-solvation temperatures of the MeOH derivatives 4–6 were slightly higher in comparison to their hydrated counterparts.