Synthesis of crystalline beta-FeSi2 under high-temperature and high-pressure.

In this paper, we report the synthesis of crystalline beta-FeSi2 via the reaction of Si and Fe powders under high-temperature and high-pressure. X-ray diffraction and Raman scattering results confirm formation of the beta-FeSi2 phase. Scanning electron microscopy, high-resolution transmission electron microscopy, and selected-area electron diffraction patterns show that the beta-FeSi2 phase coexists with Si phase with small nanocrystal sizes. The formation of the beta-FeSi2 phase is a result of Si diffusion into Fe region. The obtained results suggest that the removal of Si phase can be reached through increasing Fe content and prolonging the duration of high-pressure thermal treatment.

Evaluation for synergistic suppression of T cell responses to minor histocompatibility antigens by chloroquine in combination with tacrolimus and a rapamycin derivative, SDZ-RAD.

The 4-aminoquinolines, chloroquine and hydroxychloroquine, can suppress chronic graft-versus-host disease (GVHD) following blood and marrow transplantation (BMT) in mice and humans, respectively. We hypothesized that chloroquine in combination with tacrolimus and the rapamycin derivative SDZ-RAD can synergistically suppress T cell responses and antigen-presenting cell (APC) function in vitro. We used the APC-dependent C57BL/6 anti-BALB.B T cell response and APC-independent anti-CD3epsilon antibody-induced response to evaluate the role of synergism between chloroquine and tacrolimus or SDZ-RAD on each component of a T cell response to minor histocompatibility antigens. We found that chloroquine with tacrolimus had a greater synergistic suppression of APC-dependent compared to the APC-independent T cell responses, with a combination index (CIx) for 50% inhibition by mean effect analysis of 0.16 and 0.50, respectively (a lower number indicates greater suppression). By contrast, chloroquine with SDZ-RAD had a similar CIx between the two responsed 0.50 vs0.45) suggesting only T cell suppression. Synergy between chloroquine and SDZ-RAD involved a direct effect on T cell cytokine production, whereas synergism between chloroquine and tacrolimus was due to an effect on both T cells and APCs. We conclude that the renal-sparing 4-aminoquinolines may be used syneristically with immunosuppressive drugs currently used for BMT.

Studies on the reactogenicity and immunogenicity of the BRD-2 and RA27/3 live attenuated rubella vaccines.

A study to compare the reactogenicity and immunogenicity of the BRD-2 and RA27/3 rubella vaccine strains was conducted in GuangXi, China in 1982. Ninety eight susceptible children between two and six years of age, with haemagglutination inhibition (HI) antibody titres of less than 10, were inoculated with RA27/3 vaccine strain. A similar group of 103 children were inoculated with BRD-2 vaccine strain; 110 uninoculated children served as a control group. The percentages of children who had fever reactions were 30.09% for RA27/3, 20.04% for BRD-2, and 24.50% for the uninoculated group. Neither vaccine evoked a high fever reaction. For both vaccines, the seroconversion rates estimated 42 days after immunization were 100%. The geometric mean titre of HI antibody was 144.4 +/- 2.04 for recipients of RA27/3, and 116.1 +/- 2.0 for those vaccinated with BRD-2. The rate of excretion of virus from the nose and throat was 26.67% for the recipients of RA27/3 and 23.08% for those who received BRD-2. No vaccine virus was isolated from the uninoculated susceptibles who were in close contact with the vaccinated children. Furthermore, the latter group remained seronegative when tested after 42 days of contact with the vaccinated. Hence, it appears that both RA27/3 and BRD-2 vaccine viruses have no capacity for being transmitted to unvaccinated contacts. In susceptible adolescents immunized with the BRD-2 vaccine viruses have no capacity for being transmitted to unvaccinated contacts. In susceptible adolescents immunized with the BRD-2 vaccine strain, a mild febrile reaction was observed.(ABSTRACT TRUNCATED AT 250 WORDS)