Rayleigh Light-scattering Technique Research Articles

Temperature induced multiple structure transformation and aggregation behaviors of amphiphilic acrylicpimaric acid polyglycol ester in water

In this work, amphiphilic acrylicpimaric acid polyglycol ester (APAPG) was synthesized by steglich esterification method. The structure transformation and aggregation behaviors of APAPG in water were investigated by Rayleigh light scattering (RLS) technique in a heating and cooling cycle. For concentration above critical micelle concentration (CMC), a reversible transition from micelle to aggregation was observed. The structure transformation process involved irreversible aggregation and disaggregation processes at low temperature and a reversible aggregation process at high temperature when the concentration closed to CMC. Accordingly, the information about each structure transformation behavior in the concentration far below CMC during heating process including individual unimers, aggregation and disaggregation were thoroughly revealed. However, the structure transformation behavior is irreversible in the cooling process. The structure transformation and aggregation behaviors were assessed by dynamic light scattering (DLS), microcalorimetry and scanning electron microscopy (SEM) techniques. The results indicate that the RLS technique can provide detailed information about structural evolution at molecular level of polymer chains.

Time-resolved velocity and concentration measurements in variable-viscosity turbulent jet flow

This paper addresses the ability to reliably measure the fluctuating velocity field in variable-viscosity flows (herein, a propane–air mixture), using hot-wire anemometry. Because the latter is sensitive to both velocity and concentration fluctuations, the instantaneous concentration field also needs to be inferred experimentally. To overcome this difficulty, we show that the hot-wire response becomes insensitive to the concentration of the field, when a small amount of neon is added to the air. In this way, velocity measurements can be made independently of the concentration field. Although not necessary to velocity measurements, Rayleigh light-scattering technique is also used to infer the local (fluctuating) concentration, and, therefore, the viscosity of the fluid. Velocity and concentration measurements are performed in a turbulent propane jet discharging into an air–neon co-flow, for which the density and viscosity ratios are 1.52 and 1/5.5, respectively. The Reynolds number (based on injection diameter and velocity) is 15400. These measurements are first validated: the axial decay of the mean velocity and concentration, as well as the lateral mean and RMS profiles of velocity and concentration, is in full agreement with the existing literature. The variable-viscosity flow along the axis of the round jet is then characterized and compared with a turbulent air jet discharging into still air, for which the Reynolds number (based on injection diameter and velocity) is 5400. Both flows have the same initial jet momentum. As mixing with the viscous co-flow is enhanced with increasing downstream position, the viscosity of the fluid increases rapidly for the case of the propane jet. In comparison with the air jet, the propane jet exhibits: (1) a lower local Reynolds number based on the Taylor microscale (by a factor of four); (2) a reduced range of scales present in the flow; (3) the isotropic form of the mean energy dissipation rate is first more enhanced and then drastically diminishes and (4) a progressively increasing local Schmidt number (from 1.36 to 7.5) for increasing downstream positions. Therefore, the scalar spectra exhibit an increasingly prominent Batchelor regime with a ~ k −1 scaling law. The experimental technique developed herein provides a reliable method for the study of variable-viscosity flows.

Determination of Protein in Milk Powder Using 2-Sulfophenylazo-Rhodanine as a Probe by the Enhanced Resonance Rayleigh Light-Scattering Technique

In this paper, the interaction between 2-sulfophenylazo-rhodanine and protein was investigated by Rayleigh light-scattering technique. Based on this, a novel method for the determination of protein was developed. The effects of different conditions, such as acidity and media, were investigated thoroughly, and the optimum conditions were confirmed. Bis(2-ethylhexyl)sulfosuccinate (AOT) microemulsion, which is introduced into the protein determination, markedly increased the sensitivity of the system by changing the microenvironment. In pH 2.80 Britton-Robinson buffer solution in the presence of AOT microemulsion, the detection limits of bovine serum albumin, human serum albumin, ovalbumin, and gamma-globulin are 5.4, 4.5, 9.8, and 10.1 ng/mL, respectively. The method developed in this paper has been applied to the determination of protein in milk powder with satisfactory results.

Determination of Trace Proteins by Rayleigh Light Scattering Technique with Indophenol Blue

The interaction of indophenol blue (IPB) with proteins in aqueous solution has been studied by optical absorption and Rayleigh light scattering (RLS) spectroscopy. At pH 3.8, the weak RLS of IPB is enhanced by proteins. Based on this phenomenon, a novel method for the determination of proteins at nanogram levels using the RLS technique is developed. The method is simple, practical and sensitive. The linear range is 0.25−20.9 µg mL−1 for BSA, and 0.25−17.6 µg mL−1 for HSA. The detection limits (S/N = 3) are 23 ng mL−1 for BSA and 22 ng mL−1 for HAS. The results for the determination of proteins in human serum samples are very close to those obtained by an established clinical method. There is very little interference from amino acids, metal ions or other coexisting compounds.

Sensitive determination of sulfate in drinks and vegetables digests by Rayleigh light scattering technique.

In this paper, a novel and sensitive method based on Rayleigh light scattering technique (RLS) was proposed for the determination of sulfate using a conventional spectrofluorometer. Sulfate was transformed to BaSO4 particles, which displayed intense light scattering in aqueous solutions. The effects of factors such as wavelength, acidity, stabilizers and interferents were studied in detail. The RLS intensity of the BaSO4 suspension was obtained in 0.1 mol L(-1) of [H+] and the addition of 2 mL of cationic polyacrylamide (CPAM) with 7.05 x 10(-3) mmol mL(-1) charged cations and 1.0 mL of BaCl2.2H2O (5.0%) at 510 nm. In the range of 8-400 microg mL(-1), RLS intensity was linear to the concentration of BaSO4, and the detection limit was 0.3 microg mL(-1). To determine the feasibility of the proposed method, some samples of water, drinks, and vegetables digests were analyzed, and the results were in agreement with the standard turbidimetric method. Good recovery results were also obtained in the range of 94-105%. Although this method was limited in stability, it was characterized with simplicity, sensitivity, reliability, and little interference.

Determination of nucleic acids with tetra-( N-hexadecylpyridiniumyl) porphyrin sensitized by cetyltrimethylammonium bromide (CTMAB) using a Rayleigh light-scattering technique

Using a common spectrofluorometer to measure the intensity of Rayleigh light-scattering (RLS), a method for determination of nucleic acids has been developed. At pH 10.24 and ionic strength 0.01 mol l −1 (NaCl), the Rayleigh light-scattering of the tetra-( N-hexadecylpyridiniumyl) porphyrin (TC 16PyP) is greatly enhanced by nucleic acids in the presence of cetyltrimethylammonium bromide (CTMAB), with the scattering peak located at 311.8 nm. The enhanced RLS intensity is in proportion to the concentration of calf thymus DNA (ctDNA) in the range 0.2–6.0 μg ml −1 and to that of fish sperm DNA (fsDNA) in the range 0.05–3.0 μg ml −1. The limits of detection are 0.016 μg ml −1 for calf thymus DNA and 0.023 μg ml −1 for fish sperm DNA when the concentration of TPP was chosen 2.0×10 −6 mol l −1. Four synthetic samples were determined satisfactorily.

Quantitative determination of proteins by the Rayleigh light-scattering technique after optimization of the derivation reaction with Arsenazo-DBS

This paper researched the determination of proteins with 2-(2-arsonophehenylazo)-7-[(2,6-dibromo-4-sulfophenylazo)-1,8-dihydroxynaphthalene-3,6-disulfonic acid (Arsenazo-DBS) by Rayleigh light-scattering (RLS). The reaction parameters, such as acidity, volume of buffer solution and concentration of Arsenazo-DBS, were examined by orthogonal array design (OAD). Under optimal conditions, the weak RLS of Arsenazo-DBS and BSA can be enhanced greatly and two enhanced RLS signals were produced at 340–350 and 400–420 nm. Based on this reaction, a new quantitative determination method for proteins has been developed. This method is proved to be very sensitive (the determination limits are 0.077 μg ml −1 for bovine serum albumen (BSA) and 0.074 μg ml −1 for human serum albumen (HSA)), rapid (<2 min), simple (one step) and tolerance of most interfering substances. The effects of different surfactants were also examined. The amount of proteins in human serum samples was determined and the maximum relative error was no more than 2% and the recovery was between 95 and 105%.

Study of the interaction of protein and dibromomethyl–Arsenazo–Al(III) by Rayleigh light-scattering technique

Based on the weak Rayleigh light scattering (RLS) of the complex of dibromomethyl (DBM)–Arsenazo–Al(III) which can be enhanced by the addition of protein in weak acidic solutions, a novel method for the determination of protein concentrations has been proposed by using a commonly used spectrofluorimeter. Four proteins, including bovine serum albumin (BSA), human serum albumin (HSA), lysozyme and egg albumin were tested. The dynamic range, for example HSA is 2.5–50.0 μg ml −1 and the 10 σ determination limit is 83 ng ml −1. This method has been applied to the determination of proteins in human serum samples, and the results are very close to those provided by clinical physicians. There is very little interference from amino acids, metal ions and other coexisting compounds. The assay is convenient, rapid, inexpensive and simple.

Microdetermination of proteins with the arsenazo-DBN-Al(III) complex by Rayleigh light-scattering technique and application of the method.

The determination of proteins with arsenazo-DBN and Al3+ by Rayleigh light-scattering (RLS) is described. The weak RLS of arsenazo-DBN and BSA can be enhanced greatly by addition of Al3+ in the pH range 5.3-7.0; this resulted in two enhanced RLS signals at 420-440 nm and 460-480 nm. The reaction between arsenazo-DBN, Al3+, and proteins was studied and a new method was developed for quantitative determination of proteins. This method is very sensitive (0.34-41.71 microg mL(-1) for bovine serum albumin, BSA, and 0.29-53.41 microg mL(-1) for human serum albumin, HSA), rapid (< 2 min), simple (one step), and tolerant of most interfering substances. The effects of different surfactants were also examined. When these proteins were determined in four human serum samples the maximum relative error was not more than 2% and the recovery was between 97 and 103%.

A sensitive and rapid method for the determination of protein by the resonance Rayleigh light-scattering technique with Pyrogallol Red.

The resonance Rayleigh light-scattering (RRLS) technique was used to develop a simple, sensitive and selective method for the determination of proteins. The method is based on the interaction between proteins and Pyrogallol Red (PR) in the pH range 3.6-4.2, which causes a substantial enhancement of the resonance scattering signal of PR in the wavelength range 300-450 nm with the maximum scattering peak located at 347 nm. With this method, 0.25-13 microg ml(-1) of bovine serum albumin (BSA), 0.25-10 microg ml(-1) of human serum albumin (HSA) and 0.25-13 microg ml(-1) of human immunoglobulin G (IgG) can be determined, and the detection limits, calculated as three times the standard deviation of nine blank measurements, for BSA, HAS and IgG were 51, 48 and 57 microg l(-1), respectively. Moreover, the method shows almost no protein-to-protein variability and is free from interference from many amino acids and metal ions. The method, with high sensitivity, selectivity and reproducibility, was satisfactorily applied to the determination of the total protein in human serum and saliva samples. Mechanism studies indicated that PR can bind to BSA depending mainly on electrostatic forces, and this interaction can encourage the J-aggregation of PR, which results in enhanced Rayleigh light-scattering in the PR-protein system.

The synthesis and application of 1-( o-nitrophenyl)-3-(2-thiazolyl)triazene for the determination of palladium(II) by the resonance enhanced Rayleigh light-scattering technique

The resonance Rayleigh light-scattering (RRLS) signal of a new triazene reagent; 1-( o-nitrophenyl)-3-(2-thiazolyl)triazene ( o-NPTT), was firstly synthesized and characterized in this paper at 500–600 nm wavelength range and can be enhanced remarkably by Pd 2+. According to this phenomenon, a new method was developed for the determination of Pd 2+ by the RRLS technique in the presence of Tween-80. The calibration graph showed good linearity over a concentration range of 5.0–700 μg l −1 with a detection limit of 1.0 μg l −1. There are almost no foreign ions interfered in the determination at a more than fivefold concentration of Pd 2+. The method is relatively sensitive, of good selectivity and has been successfully used for the determination of trace palladium in the slag of fertilizer factories and catalyst samples.

A Study on the Reaction of Protein with Arsenazo III by Rayleigh Light Scattering Technique

A new rayleigh light scattering (RLS) assay of protein was conducted in this paper. The weak RLS of arsenazo III can be enhanced greatly by the addition of proteins. Based on this, the reaction of arsenazo III and proteins was studied. A new quantitative determination method for proteins has been developed. This method is very sensitive (0.085(021.25 μg/mL for BSA), rapid (<1min), simple (one step) and free of interference from most diverse substances.

Reverse anisotropy of the diffusion coefficients in a polymeric nematic medium

Using a forced Rayleigh light-scattering technique, we have measured the mutual diffusion coefficients in a side-chain nematic polymer in the two directions parallel and perpendicular to the director, and observed an inverted anisotropy compared to conventional nematic media. These results are interpreted in terms of the influence of the chain backbone on the nematic medium, as regards both the sign of the anisotropy and the order of magnitude of the diffusion coefficients.

Origin of Thermal Conductivity Anisotropy in Liquid Crystalline Phases

Thermal conductivity measurements have been performed in nematic and smectic liquid crystalline phases by the forced Rayleigh light-scattering technique. Results show clearly that the thermal transport anisotropy is governed by the molecular shape anisotropy and by the molecular orientation but is independent of the smectic layer ordering.