Au20Si12: A hollow Catalan pentakis dodecahedron

A stable hollow Au₂₀Si₁₂ cage with I_h symmetry has been predicted using first-principles density functional theory. The stability of the cage-like Au₂₀Si₁₂ structure is verified by vibrational frequency analysis and molecular dynamics simulations. A relatively large highest occupied molecular orbital-lowest unoccupied molecular orbital gap of 1.057 eV is found. Electronic structure analysis shows that clearly p-d hybridizations between Si atoms and Au atoms are of great importance for the stability of Au₂₀Si₁₂ cage. The cage-like Au₂₀Si₁₂ structure may have potential applications in semiconductor industry and microelectronics.

[Significance of infusion of sodium bicarbonate in amniotic cavity under continuous internal fetal heart rate monitoring for management of fetal distress during labor]

OBJECTIVE

To investigate the effect of infusion of sodium bicarbonate in amniotic cavity and exchange of amniotic fluid for fetus with distress and acidosis.

METHODS

The patients included 40 cases of oligohydramnios with mild and serious abnormality of fetal heart rate and amniotic fluid contamination of degree II or more during the labor. The 40 cases had exchange of amniotic fluid with infusion under continuous monitoring. Twenty of them had infusion with 5% sodium bicarbonate into amniotic cavity; the other 20 cases received 5% sodium bicarbonate intravenous in fusion. After the labor all the patients had test of arterial blood gas in umbilical cord and the fetuses were evaluated with Apgar score.

RESULTS

(1) the effective rate was 88% in the group of infusion into amniotic cavity and 85% in the group of exchange of amniotic fluid. (2) The arterial blood pH, PO(2), HCO(3)(-), ABE, SBE in the group of amniotic cavity infusion with 5% sodium bicarbonate were all higher than group of IV infusion, however PCO(2) was significantly lower than the group of IV (P < 0.05).

CONCLUSION

Infusion into amniotic cavity and exchange of amniotic fluid is effective therapy for fetal distress due to oligohydramnios and can prevent meconium aspiration syndrome; infusion of antacids medicine (5% sodium bicarbonate) into amniotic cavity is effective and safe therapy for fetus with acidosis.