Shape, size, hydration and flow behavior of nitrocellulose lacquer emulsion in absence and presence of urea

Viscometric and optical microscopic experiments, performed on nitrocellulose lacquer emulsions in the absence (Emulsion I) and presence (Emulsion II) of urea, indicate that in aqueous concentrated solutions at 30 C the emulsion droplets are spherical and non-spherical in shape, respectively. Assuming spherical shape for both emulsions, the size and volume of the aggregated particle (Mv), radius of gyration (Rg), hydrodynamic radius (Rh), diffusion coefficient (D), the correlation time for aggregate rotation (Tr), translational diffusion (TD) and effective aggregation time (Ta) have been derived. The viscosity data for both emulsions were analyzed in terms of the Einstein, Moulik and Jones-Dole equations. Emulsion II was more hydrated than Emulsion I, although the intrinsic viscosity (η) of Emulsion II is nearly 1.5 times greater than that of Emulsion I. The Huggins and Thomas equations have been compared for both emulsions, and it has been concluded, in light of the proposed Huggins-Thomas-Mandal equation, that the Thomas constant k1 should be 12.50 for perfect spherical shape of the particles in dilute solutions, instead of the 10.05 originally proposed by Thomas

Polyethylene Glycol-Modified Layered Double Hydroxides: Synthesis, Characterization, and Study on Adsorption Characteristics for Removal of Acid Orange II from Aqueous Solution

The present study aimed to improve the adsorption characteristics of the pristine layered double hydroxide (LDH) by physicochemical modification using polyethylene glycol (PEG(400)), a nontoxic hydrophilic polymer. With this objective, LDH was synthesized and modified with different concentrations of PEG(400). The PEG-modified LDHs (LDH/PEGs) were characterized using X-ray diffraction, thermogravimetric analysis, Brunauer-Emmett-Teller surface area and porosity measurement, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and zeta potential measurements. The adsorption properties of the pristine LDH (PLDH) and the LDH/PEGs were studied for the removal of Acid Orange II from water, and the results were compared. The PLDH treated with 15% PEG solution showed similar to 30% increase in adsorption capacity as compared to the PLDH. The adsorption isotherm data were analyzed using Langmuir, Freundlich, and Temkin isotherm models. The values of thermodynamic parameters such as Delta S and Delta H showed the spontaneous and endothermic nature of the adsorption process. The adsorption kinetics data for both PLDH and the LDH/PEG adsorbents presented a good fit to the pseudo-second-order kinetic model

A simple method for Bachmann's bundle pacing with indigenous modification of J-stylet

AbstractBackgroundPacing in the Bachmann's bundle (BB) area (upper atrial septum) appears superior to right atrial appendage or free wall stimulation for the prevention of paroxysmal atrial fibrillation in patients with atrial conduction delay. However, insertion of active fixation lead in the upper atrial septal position is difficult and time consuming with conventional stylet, inhibiting application of this pacing method in routine practice.MethodsThe technique of positioning the atrial lead in BB with hand-made stylet is presented with emphasis on electrocardiographic P-wave pattern and fluoroscopic landmarks.ResultsThe results demonstrate an acute implantation and short-term success of BB pacing of 14 patients out of 15 patients without major complications. Pacing parameters at implantation and 3 months postprocedure were noted which were within normal limits.ConclusionThese favorable initial results indicate that the positioning of active fixation atrial lead in BB with fluoroscopic landmarks is feasible and reproducible with a simple technique

Retrospect, resurgence and prospects of micelles

Recent studies on micellar systems were systematically overviewed, paying special attention to Gemini surfactants, mixed micelles, clouding phenomena and microemulsions. Gemini surfactants are surfactants that have two hydrophilic groups and two hydrophobic groups per amphiphilic molecule, rather than the single hydrophilic and single hydrophobic group of conventional surfactants. The greater efficiency and effectiveness of geminis over comparable conventional surfactants make them more cost effective as well as environmentally desirable. Mixed micelles have received wide attention for several decades, both in theoretical studies and in practical applications, because of their distinctive behaviour in comparison with normal micellar systems. Clouding (cloud point, CP) is a well known phenomenon observed in non-ionic surfactants. For charged micelles (i.e., ionic surfactants), the phenomenon rarely occurs, however, under special conditions, the CP in ionic surfactant solutions is observed. Some amphiphilic drugs, like ionic surfactants, also undergo pH-, concentration-, and temperature- dependent phase separation. It was observed that their CP can vary with additives. Due to their unique properties, namely, thermodynamic stability, ultralow interfacial tension, large interfacial area and the ability to solubilize otherwise immiscible liquids, microemulsions have attained increasing significance both in basic research and in industry. The uses and applications of microemulsions have been numerous. Several reviews on micellar systems and their applications have been published. However, this topic is developing quite rapidly and it is hoped that this review will help newcomers in the field as well as those already involved in this field

Hepatocyte growth factor incorporated chitosan nanoparticles augment the differentiation of stem cell into hepatocytes for the recovery of liver cirrhosis in mice

<p>Abstract</p> <p>Background</p> <p>Short half-life and low levels of growth factors in the niche of injured microenvironment necessitates the exogenous and sustainable delivery of growth factors along with stem cells to augment the regeneration of injured tissues.</p> <p>Methods</p> <p>Here, recombinant human hepatocyte growth factor (HGF) was incorporated into chitosan nanoparticles (CNP) by ionic gelation method and studied for its morphological and physiological characteristics. Cirrhotic mice received either hematopoietic stem cells (HSC) or mesenchymal stemcells (MSC) with or without HGF incorporated chitosan nanoparticles (HGF-CNP) and saline as control. Biochemical, histological, immunostaining and gene expression assays were carried out using serum and liver tissue samples. One way analysis of variance was used for statics application</p> <p>Results</p> <p>Serum levels of selected liver protein and enzymes were significantly increased in the combination of MSC and HGF-CNP (MSC+HGF-CNP) treated group. Immunopositive staining for albumin (Alb) and cytokeratin 18 (CK18), and reverse transcription-polymerase chain reaction (RT-PCR) for Alb, alpha fetoprotein (AFP), CK18, cytokeratin 19 (CK19) ascertained that MSC-HGF-CNP treatment could be an effective combination to repopulate liver parenchymal cells in the liver cirrhosis. Zymogram and western blotting for matrix metalloproteinases 2 and 9 (MMP2 and MMP9) revealed that MMP2 actively involved in the fibrolysis of cirrhotic tissue. Immunostaining for alpha smooth muscle actin (αSMA) and type I collagen showed decreased expression in the MSC+HGF-CNP treatment. These results indicated that HGF-CNP enhanced the differentiation of stem cells into hepatocytes and supported the reversal of fibrolysis of extracellular matrix (ECM).</p> <p>Conclusion</p> <p>Bone marrow stem cells were isolated, characterized and transplanted in mice model. Biodegradable biopolymeric nanoparticles were prepared with the pleotrophic protein molecule and it worked well for the differentiation of stem cells, especially mesenchymal phenotypic cells. Transplantation of bone marrow MSC in combination with HGF-CNP could be an ideal approach for the treatment of liver cirrhosis.</p

Physico-chemical studies of micelle formation on sepia cartilage collagen solutions in acetate buffer and its interaction with ionic and nonionic micelles

Sepia cartilage collagen (pepsin-extracted) in acetate buffer (pH = 2.98) forms micelles at a particular concentration below which they do not normally form. The critical micelle concentration (cmc) of the collagen was determined in buffer as well as in SDS, cetyltrimethylammonium bromide (CTAB) and Tween-80 micellar environments at different temperatures. Mutual interaction of collagen micelles with the ionic and nonionic micelles through the formation of the mixed micelle concept has also been found. The cmc of collagen decreased in the presence of SDS and Tween-80 micelles whereas it increased in the presence of CTAB micelles. This clearly suggests that the micelle formation of collagen is facilitated by the presence of SDS and Tween-80 and hindered by CTAB micelles. The various thermodynamic parameters were estimated from viscosity measurements and the transfer of collagen into the micelles of various surfactants and the reverse phenomenon was analyzed. This analysis has also been modelled conceptually as a different phase and the results have supported the above phenomenon. Our thermodynamic results are also able to predict the exact denaturation temperature as well as the structural order of water in the collagen in various environments. The hydrated volumes, Vh, of collagen in the above environments and intrinsic viscosity were also calculated. The low intrinsic viscosity, [&#951;], of collagen in an SDS environment compared to buffer and other surfactant environments suggested more workable systems in cosmetic and dermatological skin care preparations. The one and two-hydrogen-bonded models of this collagen in various environments have been analyzed. The calculated thermodynamic parameters varied with the concentration of collagen. The change of thermodynamic parameters from coil-coil to random-coil conformation upon denaturation of collagen were calculated from the amount of proline and hydroxyproline residues and compared with viscometric results. Thermodynamic results suggest that the stability of the collagen in the additive environments is in the following order: SDS &#62; Tween-80 &#62; buffer &#62; CTAB

The formation of copper oxide nanorods in the presence of various surfactant micelles

Copper oxide nanorods with average diameters and lengths of ca. 8 nm and 400 nm, respectively, have been prepared by a simple onestep solid-state reaction in the presence of various surfactant micelles. The effect of three different surfactants viz., SDS, CTAB and Triton X-100 and their critical micellar concentration (CMC) on the formation of nanorods has been studied using XRD, TEM, DSC and XPS techniques. It is found that the formation of the nanorods in the presence of SDS micelles is better with higher thermal stability and possessing lower binding energy with regard to Cu2p peak