Help Of Dynamic Light Research Articles

Storage and Temperature Stability of Emulsified Biodiesel-Diesel Blends.

The scarcity of fossil fuel has led to the recent worldwide commercialization of biodiesel-blended diesel. The benefits associated with emulsion fuels have encouraged researchers to study the blended emulsified fuels in diesel engines. Recent results show the effectiveness of blended emulsified fuels in terms of better fuel economy and less harmful emissions. Investigation on the stability of these blended emulsified fuels during storage in the fuel tank is equally crucial for commercialization and practical application. A systematic study on the storage stability of water in biodiesel/diesel blend nanoemulsions (nEs) is presented in this work. A mixture of two biodegradable surfactants, Span 80 and Tween 80, is used to stabilize the nEs. The nEs are formulated by subjecting a mixture of 5 vol % of each surfactant, 5 vol % of water, and 85 vol % of pure or blended diesel to high shear homogenization at 5000 rpm for 2 min. Storage stability of the emulsified fuels is studied for 65 days at 25 °C with the help of dynamic light scattering and viscosity measurements. The mean droplet size increases, and the stability decreases with an increase in the biodiesel concentration. The smallest mean droplet size is 32 nm for emulsified fuel using pure diesel, and these emulsions remain stable for 65 days. No macroscopic phase separation is observed for any sample aged for 24 days. A moderate increment in droplet sizes is observed during this period. The droplet size increases significantly when more than 15 vol % biodiesel is used in the fuel blend. Those samples show stratification after 65 storage days. An increment in the zero-shear viscosity of the samples over aging helps hinder the rapid coalescence of the droplets, thus preventing phase separation. Furthermore, the thermal stability of the samples is also investigated at elevated temperatures up to 50 °C. The nEs are found to be highly stable within this temperature range and showed a moderate change in mean droplets size, especially when the concentration of biodiesel in the emulsified fuel blend is less than 15 vol %.

Functional and Rheological Properties of Vicia faba L. Protein Isolates.

A protein isolate (85.5%) was obtained from the Vicia faba L. seeds. The main protein fraction, typical for the seeds of this plant, was found to be most numerous: Legumin (35 kDa) and Vicilin (45 kDa). The hydrodynamic and surface properties of isolate aqueous solutions were studied with the help of dynamic light scattering, -potential, and tensometry in a wide range of concentrations and pH conditions. Selected functional properties, like foaming and emulsifying abilities, were studied. An increase of water solubility was shown with a raising pH, as well as a water holding capacity (WHC). The protein isolate showed a tendency to decrease the surface tension of water solutions, with high hydrophobicity and a negative charge of the isolate enhancing the foaming and emulsifying properties. The analysis of the concentration and the pH influence on selected functional properties indicated alkaline conditions as favorable for good foaming and emulsifying properties of the isolate and affected on their rheological properties.

Influence of montmorillonite/carbon nanotube hybrid nanofillers on the properties of poly(lactic acid)

Multi-walled carbon nanotube (MWCNT) and montmorillonite (Mt) are used as reinforcing fillers in polymers. Achieving homogeneous distribution of the reinforcing nanoparticles without agglomerates in polymeric matrices continues to be an important topic in materials science. In this study, hybrid Mt/MWCNT nanofiller was prepared after determining the most stable composition with the help of dynamic light scattering (DLS). The hybrid Mt/MWCNT was characterized via X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) spectroscopy. The Mt/MWCNT hybrid fillers were incorporated in poly(lactic acid) (PLA) at concentrations of 0.5, 1 and 2 wt%, by a two-step procedure of solution and melt mixing, and their physicochemical, thermal, mechanical and morphological properties were evaluated. The physicochemical studies suggested strong hybrid-polymer interaction. The structural analyzes confirmed synergy between nanoclay and carbon nanotubes in achieving homogeneous dispersion of Mt/MWCNT nanoparticles in the PLA matrix. The thermal characterizations depicted that the Mt./MWCNT hybrid nanofillers synergistically restricted the PLA segment motions and promoted the crystallization of the polymer matrix. The mechanical properties of PLA/Mt/MWCNT nanocomposites were improved, confirming the reinforcing effect of the Mt/MWCNT hybrid on PLA matrix.

Fabrication of antimicrobial curcumin stabilized platinum nanoparticles and their anti-liver fibrosis activity for potential use in nursing care

Platinum and Curcumin conjugation using green chemistry is an attempt to enhance the curcumin effectiveness as an anti-fibrosis. In this study, Platinum and curcumin were conjugated to direct curcumin into the liver. Curcumin platinum nanoparticles (C-PtNPs) were formed by changing curcumin concentration at pH 10. The successful formation of C-PtNPs was recognized with the help of Fourier transform infrared (FTIR) and UV–visible spectrophotometers. The particle size and morphology were studied with the help of dynamic light scattering (DLS) and High-resolution transmission electron microscopy (HR-TEM) respectively. The antimicrobial activity of C-PtNPs, was examined against gram positive and gram negative bacteria. Moreover, the NIH/3 T3 cells were used to test the C-PtNPs activity of modifying initial fibrosis indication. The favorable condition for the synthesis of CPt-NPs was by using curcumin 1.5 mM at pH 10. When compared with free curcumin, C-Pt-NPs exhibited higher activity for decreased production of collagen by NIH/3 T3 cells. Altogether, the formation of C-PtNPs by conjugation of platinum to curcumin is assuring for the curcumin directing to treat the hepatic fibrosis.

Naringin-Chalcone Bioflavonoid-Protected Nanocolloids: Mode of Flavonoid Adsorption, a Determinant for Protein Extraction.

In order to highlight the applications of bioflavonoids in materials chemistry, naringin and its chalcone form were used in the nanomaterial synthesis to produce flavonoid-conjugated nanomaterials in aqueous phase. Chalcone form proved to be excellent reducing as well as stabilizing agent in the synthesis of monodisperse Au, Ag, and Pd nanoparticles (NPs) of ∼5–15 nm, following in situ reaction conditions where no external reducing or stabilizing agents were used. The mechanism of NP surface adsorption of flavonoid was determined with the help of dynamic light scattering and zeta potential measurements. Surface-adsorbed flavonoids also allowed NPs to easily transfer into the organic phase by using aqueous insoluble ionic liquid. Pd NPs attracted the excessive amount of surface adsorption of both naringin as well as its chalcone form that in turn drove Pd NPs in self-assembled state in comparison to Au or Ag NPs. An amount of surface-adsorbed flavonoids selectively determined the extraction of protein fractions from complex zein corn starch protein solution. Self-assembled Pd NPs with a large amount of surface-adsorbed naringin preferentially extracted zein fraction of higher molar mass, whereas Au and Ag NPs almost equally extracted the zein fractions of lower molar masses.

Micellization behavior of anionic surface active ionic liquid 1-butyl-3-methylimidazolium dodecylbenzenesulfonate in aqueous solutions of nonionic polymer polyethylene glycol: Insights into competing mechanisms

In this study, an understanding of interactions among the anionic surface active ionic liquid (SAIL) 1-butyl-3-methylimidazolium dodecylbenzenesulfonate [C4mim][DBS] and non-ionic low molecular weight polymer polyethylene glycol 400 (PEG 400) in aqueous solution has been developed systematically. Various techniques such as tensiometry, conductivity, dynamic light scattering (DLS), nephelometric turbidity and rheology have been employed to understand the exquisite interplay of different competing mechanisms prevailing between these unlike molecules in bulk as well as in the interfacial region. Surface activity of the current systems at air-aqueous interface have been evaluated using by deriving various important surface parameters, such as surface excess concentration (Гmax), surface pressure at interface (Πcmc), minimum area occupied by one molecule of SAIL at air-solvent interface (Αmin), adsorption efficiency (pC20) and surface tension at critical micelle concentration (cmc) (γcmc). Also, the thermodynamic parameters such as standard free energy of micellization (ΔGm°), standard enthalpy of micellization (ΔHm°) and standard entropy of micellization (ΔSm°) have been evaluated from conductivity measurements. The process of micellization has been found to be exothermic and spontaneous thermodynamically in presence of PEG supported by gain in entropy. The values of critical micelle concentration (cmc) decrease with increase in concentration of PEG which signals towards the predominance of ion-dipole interactions as well as hydrophobic interactions. However, at the higher concentration (0.045 g/L PEG), the cmc has been found to increase due to modification in surface and bulk structure of system. These results have been confirmed by the electrical conductivity measurements. The aggregate formation has also been tracked with the help of dynamic light scattering and nephelometric turbidimetry which provides useful information regarding the complexation dynamics. The rheological measurements have been carried out with the intent of understanding the complex behavior of these SAIL-polymer systems.

Large-scaled clusters in aqueous glucose solutions

The presence of large-scaled clusters with sizes of larger than 100 nm in aqueous glucose solutions has been revealed with the help of dynamic light scattering. These clusters have been assumed to be ordered regions, in which α-glucose molecules separated by water molecules have predominantly the same orientation.

Anti HIV nanoemulsion formulation: Optimization and in vitro–in vivo evaluation

The objective of the present work is to develop a dose adjustable nanotechnology based liquid formulation of efavirenz with improved bioavailability for HIV therapy. Nanoemulsion of efavirenz was developed using phase inversion composition method with the help of ternary phase diagram. Globule size of the o/w nanoemulsion was studied with the help of dynamic light scattering and further confirmed with TEM analysis. Optimized formulations were subjected for in vitro dissolution studies and in vivo studies were done in rats to calculate pharmacokinetics parameters and compared with efavirenz suspension. TEM results revealed that the globule size of optimized formulation was less than 30 nm. In vitro release profile showed more than 80% release within 6 h which was highly significant (p>0.05) and pharmacokinetic studies also proved a promising in vivo absorption profile when compared to the efavirenz suspension. The developed nanoemulsion proved to be an effective dose adjustable formulation of efavirenz for pediatric HIV therapy.

DNA-Directed Self-Assembly of Graphene Oxide with Applications to Ultrasensitive Oligonucleotide Assay

Controlled graphene or its derivatives' assembly is of growing interest in many areas. However, achieving control over their assembly into precise and predictable architectures has been challenging and is still a bottleneck to their utilization. Herein, we report for the first time the use of DNA hybridization for the controllable assembly of a graphene nanosheet. Moreover, with the help of dynamic light scattering technique, we extended the above studies by exploiting the DNA-graphene dispersed sheets as highly ultrasensitive detection of oligonuleotides for the fabrication of a novel biosensing strategy, which shows high sensitivity and excellent selectivity. This work will show a new general route to graphene-based lamellar composite materials and would bring about advances in the research of graphene-based biofunctional materials for specific applications in biodiagnostics, nanoelectronics, and bionanotechnology.

Dynamic light scattering by κ- and λ-carrageenan solutions

The intensity correlation functions of κ- and λ-carrageenan in various salt solutions and at different concentrations have been determined with the help of dynamic light scattering. From the first cumulant of these correlation functions the values of the translational diffusion coefficients D have been derived. They increase with macromolecular concentration. The extrapolated values to infinite dilution of the diffusion coefficients increase with increasing salt concentration as expected from the salt concentration dependence of the r.m.s. radii of gyration determined previously by static light scattering. The translational diffusion coefficient of λ-carrageenan in 0.1 m NaCl is smaller than the corresponding value for the κ species. This is consistent with the difference in contour length and linear charge density of the two samples used. No satisfactory interpretation for the concentration dependence of the diffusion coefficient seems to be possible at present. Although current theories for the macromolecular and salt concentration dependence of D, taking into account charge effects, seem to be applicable, they do not allow for a consistent interpretation of the data. No specific difference between the solution behavior of κ- and λ-carrageenan has been detected.