Liquid crystalline of a new carbosilane dendrimer of the second generation (D2) containing thirty-six 4-nitroazobenzene groups in its periphery was characterized by means of polarizing optical micrograph, DSC and WAXD. Mesogenic compound M5 exhibits threaded, schlieren and inversion lines texture of the nematic phase on the cooling from isotropic phase to solidified temperature. Dendrimer D2 shows the focal conic fan-shaped texture of the smectic A phase on the heating course from 69 to 187 degreesC and on the cooling course from 183 to 64 degreesC. After cooling, the smectic E(SE) phase with a texture of the focal conic fan-shape with stripes and concentric arcs appears from smectic A(SA) phase. Phase behavior of dendrimer D2 in liquid crystalline state was K69S(A)187I182S(A)57S(E)47K. The isotropic-smectic A transition enthalpy, smectic A-smectic E transition enthalpy and isotropic-smectic A transition entropy were 1.8, 4.5 and 4.0 J/(K (.) mol), respectively, and were in agreement with or close to those of small molecular liquid crystal.

Mass spectrometric-based techniques possesses advantages such as directness, simplicity, rapid and economy in study of biomacromolecule. In the past decade, matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) and electrospay ionization mass spectrometry (ESI-MS) have made important contributions to the field of immunology. The article reviews the application of mass spectrometric-based techniques to study the structures of immune molecules such as antigens, antibodies, antigen-antibody complexes and protein epitopes. The contents are divided into four main aspects: the analyses of molecular mass, post translational modifications, heterogeneity and conformations of immune molecules; mass mapping of proteolysis products and sequencing by tandem mass spectrometry; confirming of antigen-antibody complexes; sequencing B-cell or T-cell epitopes in proteins. These results are important for understanding immune functions of immune molecules, showing promise for the early diagnosis of disease associated with viral and bacterial infection and developing novel therapeutics and vaccines.

The divergent synthesis of a new carbosilane liquid-crystalline(LC) dendrimer(D1) was described. Twelve 4-hexyloxyazobenzene groups (M3) were used as mesogenic fragments and-attached to its periphery. Structure and properties of D1 were characterized by means of elemental analysis, H-1 NMR, IR, UV, MALDI-TOF-MS, polarizing optical micrograph, DSC and WAXD. D1 is a nematic liquid crystal, which is the same as M3. The mesomorphic behaviour of the dendrimer depends on that of the mesogenic units. Phase behavior of D1 is K92N126I124N78K. m. p. of Ell is 24-30 degreesC lower than that of M3, its clearing temperature is 13-8 degreesC higher than that of M3 and its mesophase region is 30 similar to 38 degreesC wider than that of M3. The clearing enthalpy of D1 accords with the value that is commonly found for n-i phase transition in LC and LC polymers. This may be due to the deformation of branched dendrimer D1 which can be change to fit into the anisotropic LC phase structure. Eight extinguished brushes emanating from a stationary point are observed, corresponding to the high-strength disclination of S = + 2 of dendrimer.

The divergent synthesis of a new carbosilane liquid crystalline(LC) dendrimer of the second generation(D2) was described. Thirty-six 4-hexyloxyazobenzene groups (M3) were used as mesogenic fragments and attached to its periphery. The structure and properties of D2 were characterized by elementary analysis, H-1 NMR, MALDI-TOF-MS, IR, UV, polarizing optical micrograph, DSC and WAXD. It is argued that mesophase of nematic type is realized. It is shown that the mesophase type of the dendrimer D2 and D1 essentially depends on the chemical nature of the mesogenic groups and is the same as that of mesogenic unites. The phase behavior of D2 in LC state is K90N105H11N75K. The melting point of D2 decreases 26-33 degreesC than that of M3, the temperature at its clear point decreases 3-15 degreesC than that of M3 and its mesophase region is enlarged 11-30 degreesC than that of M3. The melting point of D2 decreases 2-3 degreesC than that of D1, the temperature at its clear point decreases 11-21 degreesC than that of D1 and its mesophase region decreases 8-19 degreesC than that of D1.

The divergent synthesis of a new carbosilane liquid crystalline (LC) dendrimer (D2) of the second generation is described. Thirty. six 4-butoxyazobenzene groups (NO) are used as mesogenic fragments and attached in its periphery. Structure and properties of D2 were characterized by elemental analysis, H-1 NMR, MAIDI-TOF-MS, IR, UV, polarizing optical micrograph, DSC and WAXD. Similar to NB, D2 is a nematic liquid crystal. The mesomorphic state of the dendrimer of second generation (D2) depends on that of mesogenic units. Phase behavior of D2 in LC state is K85N107I103N69K. The melting point of D2 is 27similar to41degreesC less than that of M5, the clearing point of D2 is 17similar to18degreesC less than that of M5 and the mosophase region of D2 is 10similar to23degreesC greater than that of M5. The melting point of D2 is 2similar to3degreesC greater than that of D1, the clearing point of D2 is 26similar to29degreesC less than that of D1 and the mesophase region is 29similar to31degreesC less than that of D1. Six extinguished brushes emanating from a stationary point were observed, corresponding to the high-strength disclination of S = +3/2 of dendrimer D2.

A divergent synthesis of a new carbosilane liquid crystalline (LC) dendrimer of the third generation (W) is described. 4-Butoxyazobenzene groups (NO) are used as mesogenic fragments and attached in its periphery. Structure and properties of D3 were characterized by elemental analysis, H-1 NMR, MALDI-TOF-MS, IR, UV, polarizing optical micrograph, DSC and WAXD. Similar to NO, D3 is nematic liquid crystal. The mesomorphic state of dendrimer depends on that of mesogenic units. Phase behavior of D3 in LC state is K79N126I116N. The melting point of D3 is 33 degreesC lower than that of M5. The clearing point of D3 is 2 T higher than that of M5. The mesophase region of D3 is 35 degreesC wider than that of M5.

The divergent synthesis of a new carbosilane liquid crystalline (LC) dendrimer of the first generation (D1) is described. Twelve 4-nitroazobenzene are used as mesogenic fragments and attached in its periphery and fourcarbosilane as core. Structure and properties of D1 were characterized by elemental analysis, H-1 NMR, MALDITOF-MS, IR, UV-vis, polarizing optical micrograph, DSC and WAXD. Mesogenic compound NU exhibits nematic and dendrimer D1 reveals cholesteryl and smectic E liquid crystalline state. Phase behavior of D1 in LC state is K70Ch188I185Ch58S(E)48K.

The acid effects of some proteins on measuring their molecular weights were studied using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry ( MALDI-TOF-MS) and electrospray ionization mass spectrometry (ESI-MS). It was found that the signal intensity was enhanced through adjusting the acid concentration in some protein samples. In this paper, both MALDI-MS and ESI-MS was applied to examine the molecular weights of several standard proteins. And the proper acid concentration was detected in these spectra. In the meanwhile, it demonstrates that some associations of proteins in solution can be preserved into the gas phase and observed by the "soft ionization" mass spectrometry.

The endrohel metallofullerene, Gd@C-82, Gd@C-80, Gd-2@C-80 were synthesized by using K-H method. The technique of two-step of high pressure and high temperature extraction with 1, 3, 5-trimethylbenzene (first step) and pyridine(second step) has been successfully utilized to extract metallofullerene of Gd@C-82 The gas-phase negative ions of fullerenes C-n(n= 60, 70, 78, 82, 84...) and metallofullerene (Gd@C-82) have been studied by the ESI-MS, REC-MS and MALDI-TOF-MS. The differences among the mass spectra of ESI-MS, REC-MS and MALDI-TOF-MS have been observed and explained. In contrast to the empty fullerene C-82 , the metallofullerene Gd@C-82 should have a larger HOMO-LUMO gap. Experimental results suggest that Gd@C-82 is polarized and Gd3+ located in the off-center position of C-82 cage after Gd3+ is trapped into C-82 cage.

Rabies virus was used as the antigen to immunize laying chickens. Anti-rabies virus immunoglobulin Y(IgY) was isolated from yolks of the eggs laid by these chickens using a two-step salt precipitation and one-step gel filtration protocol. The purified IgY was reduced with dithiothreitol, and heavy chains (HC) and light chains (LC) were obtained. In addition, the purified IgY was digested with pepsin and the fragment with specific antigen binding properties (Fab) was produced. Using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOFMS), the average molecular weights of IgY, HC, LC, and Fab were determined as 167 250, 65 105, 18 660, and 45,359 Da, respectively. IgY has two structural differences compared with mammalian IgGs. First, the molecular weight of the heavy chain of IgY is larger than that of its mammalian counterpart, while the molecular weight of the light chain of IgY is smaller. Second, upon pepsin digestion, anti-rabies virus IgY is degraded into Fab, in contrast to mammalian IgG, which has been reported to be degraded into F(ab')(2) under the same conditions.

Combination of affinity extraction procedures with mass spectrometric analyses is termed affinity-directed mass spectrometry, a technique that has gained broad interest in immunology and is extended here with several improvements from methods used in previous studies. A monoclonal antibody was immobilized on a nitrocellulose (NC) membrane, allowing the corresponding antigen to be selectively captured from a complex solution for analysis by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). This method was also used to rapidly determine the approximate binding region responsible for the antibody/antigen interaction. The tryptic fragments of antigen protein in buffer were applied to the antibody immobilized on NC film and allowed to interact. The NC film was then washed to remove salts and other unbound components, and subjected to analysis by MALDI-TOFMS. Using interferon-alpha(2a) and anti-interferon-alpha(2a) monoclonal antibody IgG as a model system, we successfully extracted the antigen protein and determined the approximate binding region for the antigen/antibody interaction (i.e., the tryptic fragment responsible).

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MAIDI-TOF-MS) was used for analysis of poly(arylene phosphonate) cyclic oligomers. A comparison was made by using 1,8,9-dithranol, 2,5-dihydroxybenzoic acid and retinoic acid as the matrix. The result showed that the retinoic acid produced the strongest ion signals under the conditions used. Different salts of metals were used as the cationization agents to examine the effect on the cyclic oligomers. It was found that the salts could produce metal-cyclic oligomer cation spectra and lithium was the stronger one than those of silver so, the suitable matrix and cationization agent for the new cyclic oligmer were obtained. They were very effective for the analysis of poly(arylene phosphonate) cyclic oligomer.

Monodispersed polyaniline oligomers was studied by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS), It is found that MALDI-TOF-MS is not only a direct, accurate and rapid tool for the analysis of monodispersed polyaniline oligomers, but also a useful technique for the design of synthetic route.

Recent advances in the gas - phase reaction of aromatics with cationic electrophiles are reviewed. The overall substitution reaction is analyzed in terms of its elementary steps. Mechanistic studies have been focused on the structure and reactivity of covalent and non - covalent ionic intermediates, which display a rich chemistry and provide benchmark reactivity models. Particular attention has been devoted to proton transfer reactions, which may occur intra or intermolecularly in arenium intermediates.

Using matrix-assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS). The homogeneities and molecular weights of three arginine esterases from snake venom, which possessing therapeutic use in myocardial infarction, were determined and compared, MALDI-TOF-MS is possessed of high accuracy, high sensitivity and rapidity. MALDI-TOF-MS and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) can provide complementary and confirmatory results information. MALDI-TOF-MS can be directly used as an important method for the purification of snake venom complexes successfully.

The matrix-assisted laser desorption ionization mass spectrometry (MALDI-TOF-MS) spectra of four enzymes (PLA, AEase, Fibrolase, L-a.a. oxidase) in Agkistrodon blomhoffii Ussurensis venom, were given and interpreted. The experiment data showed that MALDI-TOF-MS can be used directly in enzyme analysis with high sensitivity and rapidity. In addition, the results were better than those from sodium dodecyl sulfate-polyacrylamide.

The cyclic aryletherketone( sulfone) oligomers containing hexafluoroisopropylidene unit were characterized by matrix-assisted laser desorption ionization time-of-night mass spectrometry(MALDI-TOF-MS) using Na+ and Ag+ as cationization agents. The affinities of cyclic oligomers to the cation were studied. The analysis result showed that 1,8,9-dithranol, in the presence of silver trifluoroacetate, was very effective for the characterization of cyclic arylether ketone ( sulfone) containing hexafluoroisopropylidene unit.