Observation of the Exotic 0_{2}

We report here the first observation of the 0_{2}^{+} state of ^{8}He, which has been predicted to feature the condensatelike α+^{2}n+^{2}n cluster structure. We show that this state is characterized by a spin parity of 0^{+}, a large isoscalar monopole transition strength, and the emission of a strongly correlated neutron pair, in line with theoretical predictions. Our finding is further supported by the state-of-the-art microscopic α+4n model calculations. The present results may lead to new insights into clustering in neutron-rich nuclear systems and the pair correlation and condensation in quantum many-body systems under strong interactions.

New

The discrepancy between observations from γ-ray astronomy of the ^{60}Fe/^{26}Al γ-ray flux ratio and recent calculations is an unresolved puzzle in nuclear astrophysics. The stellar ß-decay rate of ^{59}Fe is one of the major nuclear uncertainties impeding us from a precise prediction. The important Gamow-Teller strengths from the low-lying states in ^{59}Fe to the ^{59}Co ground state are measured for the first time using the exclusive measurement of the ^{59}Co(t,^{3}He+γ)^{59}Fe charge-exchange reaction. The new stellar decay rate of ^{59}Fe is a factor of 3.5±1.1 larger than the currently adopted rate at T=1.2 GK. Stellar evolution calculations show that the ^{60}Fe production yield of an 18 solar mass star is decreased significantly by 40% when using the new rate. Our result eliminates one of the major nuclear uncertainties in the predicted yield of ^{60}Fe and alleviates the existing discrepancy of the ^{60}Fe/^{26}Al ratio.

Observation of enhanced monopole strength and clustering in (12)Be.

In a recent breakup-reaction experiment using a Be12 beam at 29 MeV/nucleon, the 0+ band head of the expected He4+He8 molecular rotation was clearly identified at about 10.3 MeV, from which a large monopole matrix element of 7.0±1.0 fm2 and a large cluster-decay width were determined for the first time. These findings support the picture of strong clustering in Be12, which has been a subject of intense investigations over the past decade. The results were obtained thanks to a specially arranged detection system around zero degrees, which is essential in determining the newly emphasized monopole strengths to signal the cluster formation in a nucleus.

[Study on the reaction between 3-amino-6-dimethylamino-2-methlphenazine hydrochloride and deoxyribonucleic acid].

The interaction of deoxyribonucleic acid (DNA) and 3-amino-6-dimethylamino-2-methlphenazine hydrochloride (ZR) was investigated by UV spectrophotometric method in solution (pH 7.4). When DNA was added into ZR solution, the red color was observed, which indicated formation of the DNA-ZR complex. The maximum absorption of the complex was 520 nm with the apparent molar absorptivity of epsilon = 1.5 x 10(6) mol-1.L.cm-1. The maximum absorption of the complex was shifted 70 nm than with ZR. The maximum binding number is n = 303. The basic reaction conditions were investigated. It is found that sodium chloride concentration of the solution has significant effect on the sensitivity of DNA-ZR complex. The Scatchard model is appropriate in the treatment of data obtained here.

A study on the interaction between concanavalin A and glycogen by light scattering technique and its analytical application.

The mixture of concanavalin A (Con A) and glycogen shows strong light scattering character. Based on it, the interaction between Con A and glycogen was studied on a common spectrofluorimeter by light scattering technique. Many factors affecting the light scattering intensity (LSI), such as pH, temperature, reaction time, ion strength and the denaturing agent of protein were studied in detail. Experimental results showed that the LSI reached its maximum after mixing Con A with glycogen for about 20 min in pH 7.4 Tris-HCl buffer at 37 degrees C. The results also suggested that the conformation of Con A was critical for its unique binding affinity to glycogen. Electrostatic forces should not be the primary interaction between glycogen and Con A. Under proper experimental conditions, the determination method for glycogen by light scattering technique was developed. The glycogen determination can be performed in the range of 0.48-32.0, 0.50-32.0 and 0.32-24.0 mug/ml for Rabbit liver glycogen (RL Gly), Oyster glycogen (O Gly) and Clam Glycogen (C Gly), respectively. The influence of co-existing substances such as proteins, mono- and di-saccharides and metal ions was evaluated, and little interference came from the foreign substances. The determinations of glycogen in synthetic samples demonstrated that the recovery rate was in the range of 98.1-103% and the relative standard deviations (RSD) were lower than 5.0%.

The specificity of a chlorphenamine-imprinted polymer and its application.

A chlorphenamine-imprinted polymer was prepared in this study. Chromatographic analysis showed that the retentivity and selectivity of the imprinted polymer were greatly strengthened through molecular imprinting. As a consequence, chlorphenamine could be easily separated from diphenhydramine. Ionic interaction was proved to be the main power for the imprinted polymer to bind chlorphenamine. The strong extraction ability of the imprinted polymer for chlorphenamine in aqueous solution was evaluated further. It was shown that chlorphenamine, as low as 0.02 mumol l(-1), could be concentrated by 50 times with a recovery of more than 90% at pH 5. This study gave the potential of using the imprinted polymer for solid-phase extraction of practical samples.

Determination for micro amounts of nucleic acids by a resonance light scattering technique with dequalinium chloride.

Based on the strong enhancement effect of nucleic acids on resonance light scattering of dequalinium chloride, the determination method for micro amounts of nucleic acids has been developed. Under the experimental conditions (5.0x10(-5) mol l(-1) dequalinium, pH 7.0, at room temperature) the linear range of this assay is 0.04-10.0 mug ml(-1) for calf thymus DNA and fish sperm DNA, and 0.04-35.0 mug ml(-1) for yeast RNA. The detection limits (3sigma) are 6.2 ng ml(-1) for calf thymus DNA, 7.4 ng ml(-1) for fish sperm DNA, and 7.0 ng ml(-1) for yeast RNA, respectively. Almost no interference can be observed from ionic strength, proteins, nucleoside, and most of the metal ions. Six synthetic samples were determined satisfactorily.

Molecular spectroscopy study of the reaction of nucleic acids with brilliant cresol blue.

The interaction of brilliant cresol blue (BCB) with nucleic acids in aqueous solution has been studied by spectrophotometry and Rayleigh light scattering (RLS) spectroscopy. Under suitable conditions, the RLS spectra of BCB changed significantly due to the presence of nucleic acids. RLS intensity of BCB at 364 nm is greatly enhanced with the addition of nucleic acids, and a new RLS peak is observed at 552 nm. This peak is about half the intensity of that at 364 nm. The results of this study show that BCB interacts with DNA possibly due to the cooperative effect of electrostatic attraction, intercalation, coordination and hydrophobic effect. Under optimum conditions, the increase of RLS at 364 nm of a BCB solution is proportional to the concentration of nucleic acids added. This result is the basis for a new RLS method for determination of nucleic acids. The linear range of ctDNA, fsDNA and yRNA is 0.12-4.70, 0.11-4.64 and 0.43-7.07 microg ml(-1), respectively.

Rayleigh light scattering study on the reaction of nucleic acids and methyl violet.

A new quantitative determination method for nucleic acids in aqueous solutions, based on the enhancement of Rayleigh light scattering of methyl violet by nucleic acids, has been developed. The sensitivity of the assay allows amounts of nucleic acids as little as 100 ng/ml to be quantitated reliably. In addition to its high sensitivity, this method has other advantages: rapidity of reaction (<5 min), simplicity of operation (one-step assay), commonality of spectrofluorimeter and reagents, stability of mixtures formed, and reproducibility. Under the experimental conditions, there is little or no interference from proteins, nucleosides, and most metal ions. Interference by a few metal ions, detergents, and some salts can be minimized by dilution. The method can also be used to determine the total amount of nucleic acids without the arduous choice of standard and difficult separation of DNA and RNA.

Determination of protein by its enhancement effect on the Rayleigh light scattering of carboxyarsenazo.

This is the first report on the determination of proteins based on the interaction with carboxyarsenazo (CAA) by Rayleigh light scattering (RLS). At pH 4, the weak RLS of CAA can be enhanced greatly by the addition of proteins, resulting in three characteristic peaks. Based on this, the interactions of CAA with nine kinds of proteins were studied and a new quantitative determination method for proteins has been developed. This method is very sensitive (0.10-15.3 mug ml(-1) for bovine serum albumin (BSA)), rapid (<2 min), simple (one step), tolerant of most interfering substances, and gives a close value to that of the Coomassie brilliant blue (CBB) method in the determination of proteins in human serum. Thus, the CAA assay can be useful for routine analytical purposes and may overcome some of the limitations of other currently employed methods. Mechanism studies show that the three RLS peaks correspond to the absorption valleys of the CAA-protein complex.

A linear regression method for the study of the Coomassie brilliant blue protein assay.

The interactions of Coomassie brilliant blue G-250 (CBB) with bovine serum albumin (BSA) and gamma-globulin at low pH are investigated by a spectrophotometric method. It is considered that the binding of CBB to protein is because of the weak interactions (ionic, van der Waals, hydrogen bonding, and hydrophobic). The solution equilibria involving the binding of three dye species (blue, green, and red) to protein are treated in the same way as Ringbom model used in the treatment of complexation in analytical chemistry. Based on this treatment, the formation of an isosbestic point in the absorption spectra of CBB-BSA mixtures is discussed, two mathematical models for the description of the CBB protein assay are developed. The first model is a nonlinear equation which is rigorous in theory but unreliable in use because of its optimization procedure. The second model based on an approximation is a linear equation, it allows to estimate apparent binding constant, maximum binding number, and molar absorptivity of bound dye from assay data by a linear regression method. The results of the linear regression operations are reasonable and in agreement with experimental findings. Factors which influence the sensitivity of the CBB protein assay are studied using this method. Ionic strength and acidity are found to have significant effect on the binding of CBB to protein.

Enhancement of Rayleigh light scattering of acid chrome blue K by proteins and protein assay by the scattering technique.

Rayleigh light scattering of Acid Chrome Blue K (ACBK) is enhanced greatly by proteins. Based on this, a method for protein assay in aqueous solution was developed. This assay matches the sensitivity of the colorimetric dye-binding method with a linear range of 0.136-10.88 micrograms ml-1. The measurements can be made easily on a common fluorimeter. The reaction between ACBK and proteins is completed in 2 min and the scattered light signal is stable for at lest 3 h. Protein-to-protein variability is encountered in this method as in many other protein assays. There is little or no interference from amino acids, most metal ions and complexing agents (e.g., EDTA). Interferences from salts, urea and detergents can be minimized by dilution.

Determination of nanograms of nucleic acids by their enhancement effect on the resonance light scattering of the cobalt(II)/4-[(5-chloro-2-pyridyl)azo]-1,3-diaminobenzene complex.

Using a common spectrofluorometer to measure the intensity of resonance light-scattering, a method for determination of nucleic acids in the nanogram range has been developed. In the pH range 11.5-12.0, the resonance light-scattering of the binary complex of cobalt(II)/ 4-[(5-chloro-2-pyridyl)azo]-1,3-diaminobenzene (5-Cl-PADAB) is greatly enhanced by nucleic acids, with the maximum scattering peak located at 547.0 nm. The enhanced intensity of resonance light-scattering is in proportion to the concentration of calf thymus DNA in the range 0-400 ng/mL and to that of fish sperm DNA and yeast RNA in the range 0-300 ng/mL. The limits of detection are 1.4 ng/mL for calf thymus DNA, 0.8 ng/ mL for fish sperm DNA, and 1.3 ng/mL for yeast RNA. Precision at 200 ng/mL for the three nucleic acids is 1.9%, 2.0%, and 0.8%, respectively. Six synthetic samples were determined satisfactorily. Mechanism studies showed that the nature of the reaction is that the binary complex of Co(II)/5-Cl -PADAB reacts with single-stranded nucleic acid, and the enhancement effect of nucleic acids on the resonance light scattering of the binary complex is due to the stacking of the binary complex on nucleic acids, which act as a template.

Determination of nucleic acids by a resonance light-scattering technique with alpha, beta, gamma, delta-tetrakis[4-(trimethylammoniumyl)phenyl]porphine.

The resonance light-scattering technique, using a spectrofluorometer, was first developed as a sensitive instrumental analysis method. At pH 7.48 and ionic strength 0.004, the extent of light-scattering of alpha, beta, gamma, delta-tetrakis[4-(trimethylammoniumyl)phenyl]porphine (TAPP) is enhanced by nucleic acids near 432 nm. There are linear relationships between the enhanced extents of light-scattering and the concentrations of nucleic acids in the range of 1.8 x 10(-7)-10.8 x 10(-7) M for calf thymus and fish sperm DNA and in the range of 1.8 x 10(-7)-1.8 x 10(-6) M for yeast RNA. The limit of determination (3 sigma) is 4.1 x 10(-8) M for calf thymus DNA, 4.6 x 10(-8) M for fish sperm DNA, and 6.7 x 10(-8) M for yeast RNA. Mechanism study indicates that nucleic acids react with the title porphyrin in two modes, depending on the concentrations of nucleic acids. When the molar ratio of nucleic acids to TAPP is smaller than 4:1, the hypochromicity and fluorescence quenching of TAPP by nucleic acids appear, and the enhancement of resonance light-scattering can be observed. When the molar ratio of nucleic acids to TAPP is larger than 4:1, a new fluorescent complex is formed.

Microdetermination of proteins by resonance light scattering spectroscopy with bromophenol blue.

Reaction of bromophenol blue with proteins results in an enhanced resonance light scattering at 334 nm. Based on this, a new quantitative determination method for proteins in the aqueous solution is established. This assay is characterized by high sensitivity (0.34-18.7 microg/ml), short reaction time (>2 min), and simplicity (a one-step assay). Due to protein-to-protein variability, this method gave results higher than that of the bromocresol green assay in detection of human serum albumin.

Fluorometric determination for micro amounts of albumin and globulin fractions without separation by using alpha, beta, gamma, delta-tetra(4'-carboxyphenyl)porphin.

A simultaneous determination of micro amounts of albumin and globulin fractions by fluorometry with only reagent alpha,beta,gamma,delta-tetra(4'-carboxyphenyl)porphin (TCPP) in the aqueous solution has been developed. Under the experimental conditions (5.6 x 10(-7) mol/liter of TCPP, pH 3.0, and at room temperature), the linear range of this assay was 0.09-12 microgram/ml and the detection limits (3 S/N) were 60 ng/ml for albumin and 90 ng/ml for globulin, respectively. The human serum samples were measured satisfactorily by using this method.

The interaction of Bromophenol Blue with proteins in acidic solution.

The interactions of Bromophenol Blue (BPB) with bovine serum albumin and gamma-globulin in acidic solutions were investigated by a spectrophotometric method. It was considered that the electrostatic force is the main binding force, and that the color change during the combination is due to the transformation of dye species of free acidic form into bound basic form as well as to the bathochromic and hyperchromic effects of conjugation. The formation of an isosbestic point in the absorption spectra was explained based on a new consideration about the solution equilibria. Two conditional constants, apparent binding constant and maximum binding number, were defined to express the binding ability of a dye to a certain protein under a given set of conditions, and two linear regression equations were derived to determine these two parameters and the molar absorptivity of bound dye. The Scatchard model is not appropriate in the treatment of data obtained here. The factors which influence the sensitivity of a dye binding protein assay were discussed, and the Sandell index was used to express the sensitivity of protein detection. It was found that sodium chloride concentration and acidity of the solutions have significant effect on the sensitivity of BPB protein assay.