[Raman spectroscopic study on the fluid effects in dissolution and phase transition mechanisms of gypsum].

Raman spectroscopic studies on the process of dissolution and phase transition of gypsum in different fluids were taken. Gypsum took phase transition to be anhydrite in the range from 170 degrees C to 190 degrees C in pure water, and no more change happened with decreasing temperature to room temperature. Gypsum took phase transition to be anhydrite in the range from 170 degrees C to 190 degrees C too in Na2 SO4 solution, but anhydrite can regain to be gypsum when temperature decreases to room temperature. The process of phase transition of gypsum in pure water is not reversible, but it happens in Na2 SO4 solution. The study shows that fluid effects can influence the dissolution and phase transition mechanisms of minerals and cannot be ignored.

[Research on the experiment of hydrogen isotope fractionation using diamond anvil cell and Raman spectra].

Hydrothermal diamond-anvil cell and Raman spectroscopy were used to measure the hydrogen isotope fractionation factor between gypsum and liquid water. Hydrogen isotopes of deuterium (D) and hydrogen (H) show the largest relative mass difference in all stable isotope systems. The exchange reaction between D and H would easily take place and the extent of exchange would be larger than others under same condition. So we selected the hydrogen isotopes for the investigation. The concept of fractionation factor is the quotient of ratios of heavy and light isotopes in different minerals, and can be expressed as alpha(A-B) = R(A)/R(B). There is a linear relationship between ratio of Raman peak intensities and ratio of corresponding amount of substances. So the fractionation factor between gypsum and heavy water can be expressed as [formula: see text] The experimental study for the isotope fractionation is based on the dissolution and recrystallization of minerals in aqueous solutions. The process can reach the total isotope fractionation equilibrium and get isotope fractionation factors with different temperatures. Compared with other methods, chemical synthesis one has following advantages: (1) short time for the experiment; (2) no problem about the equilibrium for isotope exchanges. It was proved that the new method would be more convenient and reliable for obtaining the isotopic fractionation factor compared with previous ways.

[Research on Raman spectra of calcite phase transition at high pressure].

The present research studied the process of phase transition from calcite-I to calcite-III under the condition of high hydrostatic pressure using hydrothermal diamond anvil cell and Raman spectrum technique. The hydrothermal diamond anvil cell is the most useful instrument to observe sample in-situation under high temperature and high pressure. The authors can get effective results from this instrument and pursue further research. The method of Raman spectra is the most useful measure tool and it can detect the material according to the spectrum. The result shows that three characteristic Raman peaks of calcite-I move to high-position with adding pressure. Water media in system becomes frozen at the pressure of 1103 MPa, and there is no change in the structure of calcite-I. The abrupt change of characteristic Raman peaks of calcite-I happens when the system pressure reaches 1752 MPa, and changed characteristic Raman peaks explain that calcite-I changes to calcite-III. There are two types of calcite-III, and type A happens in the system because of the effect of hydrostatic pressure. The characteristic Raman peak in different areas of minerals shows that the degree of phase transition becomes larger from inner part to edge part. The research also shows the advantage of hydrothermal diamond anvil cell and Raman spectrum for qualitative analysis of mineral structure using in-situ technique.

[Research on Raman spectra of benzoic acid during decarboxylic process].

The present research studied benzoic acid change in water and its Raman spectra in temperature rising period using hydrothermal diamond anvil cell and Raman spectrum technique. The hydrothermal diamond anvil cell is the most useful instrument to observe sample in-situation under high temperature and high pressure. The authors can get effective results from this instrument and pursue further research. The method of Raman spectra is the most useful measure tool and it can detect the material according to the spectrum. The result showed that there was no change in characteristic vibrational Raman peak of benzoic acid in the lower temperature period and there was no reaction between benzoic acid and water. In the process of temperature rising period, the characteristic vibrational Raman peak of benzoic acid became weaker. During the process, benzoic acid began to dissolve in water, but no chemical reaction happened. The reason for weaker Raman peak of benzoic acid is the dissolution. The characteristic vibrational Raman peak of carboxyl disappeared at 150 degrees C, which showed that decarboxylic reaction occurred on benzoic acid. But the main Raman peak of benzoic acid existed which showed that no chemical reaction existed. And then benzoic acid disappeared when temperature ascended to 170 degrees C. When the temperature of system dropped to room temperature, a kind of crystal appeared. The characteristic vibrational Raman peak of this kind of crystal showed that the crystal contained benzene ring, showing that dutrex appeared. At the same time the authors did not find the characteristic vibrational Raman peak of carboxyl, so the crystal was not benzoic acid. The whole research showed that: dutrex can disappear and be regained in the process of dissolution and recrystallization, but carboxyl cannot.

[Research on Raman spectra of heavy water at high pressure].

The present work studies the Raman spectra of heavy water at pressure from 0.1 MPa to 800 MPa at ambient temperature using the method of diamond anvil cell and Raman spectrum technique. The result shows that the Raman peak of heavy water moves to lower frequency, and the linear relationship exists between Raman shift and pressure. There is no abrupt change in Raman shift, indicating that no phase transition occurs. Raman peak of heavy water is separated, corresponding to O-D vibration inside D2O molecule as the higher frequency peak and to hydrogen bond among D2O molecules as the lower frequency peak. Research on the characters of these two kinds of Raman spectra indicates that the area of lower frequency peak for hydrogen bond among D2O molecules exhibits different changes at different pressures, and the influence of pressure on hydrogen bond among D2O molecules is not unchangeable. The area of Raman spectra peak reflects the amount of vibrations which result in the Raman spectra peak, and the change in the area of Raman spectra peak reflects the change in the amount of special vibration. Because of the strong interaction between hydrogen bonds among D2O molecules, the molecules of D2O are apt to form the symmetrical dimensional structures of tetrahedron which consists of five molecules of D2O. So the biggest area of Raman spectra peak represents the most stable structure that is the symmetrical dimensional structures of tetrahedron consisting of five molecules of D2O. This result proves that the most stable structure is existent.

Increased sensitivity for detecting avian influenza-specific antibodies by a modified hemagglutination inhibition assay using horse erythrocytes.

The hemagglutination inhibition (HI) assay is a widely used serological method to measure the levels of protective antibody responses against influenza viruses. However, the traditional HI assay which uses chicken erythrocytes is not sufficiently sensitive for detecting HI antibodies specific to avian influenza viruses. Previously, it was demonstrated that employing an assay using horse erythrocytes was able to increase the sensitivity of HI assay. The current report describes further optimization of this modified HI assay. It was shown that this method was able to increase detection of HI activities in rabbit sera immunized with H5 HA antigens, and proved that this increased sensitivity is useful in dissecting the strain specificity of HI antibody responses. In addition, the modified HI assay using horse erythrocytes increased the sensitivity of detecting HI antibodies specific for three major serotypes of avian influenza viruses, H5, H7 and H9, in people who may have asymptomatic infection with avian influenza viruses. Based on these results, the optimized use of horse erythrocytes should be standard practice for detecting HI activities against avian influenza viruses.

Novel DNA vaccine based on hepatitis B virus core gene induces specific immune responses in Balb/c mice.

AIM: To investigate the immunogenicity of a novel DNA vaccine, pSW3891/HBc, based on HBV core gene in Balb/c mice. METHODS: A novel DNA vaccine, pSW3891/HBc, encoding HBV core gene was constructed using a vector plasmid pSW3891. Balb/c mice were immunized with either pSW3891/HBc or empty vector DNA via gene gun. IgG anti-HBc responses in mouse sera were demonstrated by ELISA. Specific cytotoxicity of cytotoxic T lymphocytes (CTLs) of mice was quantitatively measured by lactate dehydrogenase release assay. RESULTS: HBcAg was expressed effectively in 293T cell line transiently transfected with pSW3891/HBc. Strong IgG anti-HBc responses were elicited in mice immunized with pSW3891/HBc. The end-point titers of anti-HBc reached the highest 1:97,200, 4 wk after the third immunization. The specific CTL killing with the highest specific lysis reached 73.25% at effector:target ratio of 20:1 in mice that received pSW3891/HBc DNA vaccine. CONCLUSION: pSW3891/HBc vaccination elicits specific anti-HBc response and induces HBc-specific CTL response in immunized Balb/c mice.

[Immunogenicity of new DNA vaccine encoding for hepatitis B virus core antigen].

OBJECTIVES: To observe immunogenicity of new DNA vaccine encoding for hepatitis B virus core antigen (HBcAg). METHODS: A new DNA vaccine (pSW3891/HBc) encoding for hepatitis B virus core antigen was constructed using plasmid pSW3891 which can be used in human. Control and experiment groups of Balb/c mice were immunized with pSW3891 or pSW3891/HBc by gene gun. Anti-HBc in sera of mice was tested by ELISA (enzyme linked immune sorbent assay). Specific cytotoxicity of cytotoxic T lymphocyte (CTL) of mice was detected by LDH release assay. RESULTS: pSW3891/HBc can express in 293T cell line effectively. Mice immunized with pSW3891/HBc showed strong anti-HBc response and specific high cytotoxicity of CTL. CONCLUSION: pSW3891/HBc induced significantly humoral and cellular immune responses in Balb/c mice.

Immunogenicities of Env glycoproteins from circulating HIV-1 isolates in China focusing on the strategy of "DNA prime plus protein boost".

BACKGROUND: The adenovirus-based HIV-1 vaccine developed by Merck Company suffered from an unexpected failure in September 2007. This generated a big shift in the strategy of HIV vaccine development with renewed focus on the induction of neutralizing antibodies. A major challenge in developing an HIV-1 vaccine is to identify immunogens and adopt delivery methods that can elicit broadly neutralizing antibodies against primary isolates of different genetic subtypes. METHODS: Most circulating HIV-1 isolates in China are composed of clades Thai-B, CRF_BC and CRF01_AE. In order to construct DNA vaccines against these 3 HIV-1 subtypes, DNA vaccines carrying the gp120 regions from HIV-1 isolates of GX48(AE), GX79(AE), NX22(BC), GS22(BC), HN24(Thai-B) were constructed. Expression of gp120 from these DNA vaccines was detected by Western blotting in transiently transfected 293T cells. Pilot immunizations of New Zealand white rabbits were performed using the strategy of "DNA prime plus protein boost" and the neutralizing antibody response was detected in a Tzm-bl cell based assay against different HIV-1 strains. RESULTS: Response of gp120-specific antibody was relatively low after DNA primes (mean titer = 10(4.72)); however, the titer of gp120-specific antibody went up with 2 protein boosts (mean titer = 10(6.81)). Above all, neutralizing antibody (Nab) titers induced by this combined approach were much better than those elicited by DNA or protein used alone (P < 0.01). Neutralizing activities of immunized rabbit sera against several pseudoviruses and laboratorial strains were evaluated, most rabbit sera primed with monovalent vaccine were capable of neutralizing only 1 of 5 viruses, however, sera primed with the polyvalent DNA vaccines were able to neutralize at least 2 of 5 viruses. CONCLUSION: Polyvalent DNA prime plus protein boost is an effective immunization strategy to broaden the neutralization breadth and further research should be performed on the basis of this pilot study.