Reduced graphene oxides: the thinnest and most lightweight materials with highly efficient microwave attenuation performances of the carbon world

In this work, reduced graphene oxide (r-GO) and graphite nanosheet (GN) were obtained via the chemical approach. Furthermore, r-GO composites and GN composites were prepared with a paraffin wax host. r-GO composites show high dielectric properties and electromagnetic interference shielding efficiency (EMI SE). Compared with the GN composites, the loss tangent and EMI SE of the r-GO composites with the same mass ratio are enhanced ∼5 to 10 times and ∼3 to 10 times, respectively. The enhanced attenuation capacity arises from higher specific surface area, clustered defects and residual bonds of the r-GOs, which increase the polarization loss, scattering and conductivity of the composite. Moreover, the higher conductivity of r-GO composites leads to higher EMI SE compared with that of GN composites. These results suggest that r-GOs are highly promising fillers for microwave attenuation in the carbon family and that r-GO composites are high-performance EMI shielding materials with application anticipated to many fields.

Antigenic analysis of recent H1N1 influenza viruses with monoclonal antibodies

Antigenic analysis of recently isolated H1 influenza viruses was performed using haemagglutination inhibition (HI) assay with monoclonal antibodies to the haemagglutinin (HA) subunit. Tests using monoclonal antibodies against the HA of the A/England/333/80 (H1N1) and A/Yamagata/120/86 (H1N1) viruses revealed that the major antigenic drift occurred in 1985 or 1986 and A/Dunedin/6/83-like virus became a major strain after 1986.

Epitope changes on the haemagglutinin molecule of recently isolated H1N1 influenza viruses

We have studied changes of epitopes on the haemagglutinin molecule (HA) of H1N1 influenza viruses isolated between 1977 and 1986. For this purpose monoclonal antibodies (MAbs) were raised against the HA of the influenza A/England/333/80 and A/Yamagata/120/86 strain viruses. In order to define the amino acid residues responsible for the change of epitopes, we prepared several HA cDNAs modified by site-directed mutagenesis and cloned them into a simian virus 40 expression vector (SVHA). The substitution of glycine with serine at position 125c (suffix indicates presence in H1 but not in H3 subtype HAs) on the HA of the influenza A/USSR/90/77 strain virus resulted in the loss of epitope 110 (epitopes were named after MAbs) and created new epitopes 139 and 15, which were observed on the HA of A/England/333/80 and a few isolates from 1983. These new epitopes disappeared from the HA in some of the isolates in 1983 and most of the isolates in 1984 and 1986. The disappearance of epitopes 139 and 15 seems to be associated with the loss of epitope W18, which was identified on the HA of A/USSR/90/77. We suggested previously that amino acid residue 189 was involved in epitope W18. We therefore expressed an HA protein with two amino acid substitutions at positions 189 and 125c and found that the conversion of glutamine to lysine at position 189 in SVHA-67 prevented the expression of epitopes 139 and 15.

Time-lapse microcinematographic and phase contrast studies on the cell reformation of Chirocephalus yolk granules in vitro

In this article we report on a time-lapse microcinematographic and phase contrast study of the cell reformation of yolk granules which were isolated from mature oocytes in the genital sac of the middle female intersex of Chirocephalus nankinensis. The observations on yolk granules were made in fixed positions and the morphological changes of cell reformation were continuously recorded in vitro. The transformation of yolk granules into cellular structures may be tentatively described as follows: At the early stages in culture, it can be seen that the granular or bubbly structures gradually appear within the hyaloid and homogeneous yolk granules; the appearance of yolk granules gradually changes from elliptical into round shape. With further transformation, their appearances in general take the shape of oblate spheroids, their size is smaller than before and inside the yolk granules their granular and bubbly structures become more and more obvious. Finally, the nuclear and cellular structures can be seen in these transforming yolks. By means of time-lapse microcinematographic and phase contrast examinations in fixed positions, single yolk granules obtained from the mature oocyte with little amounts of adhering cytoplasm are continuously recorded and have been shown to occur, steadily and gradually build up cellular structures by self-organization and self-assembly. Up to the present, we have cultured these kinds of cellular organizations repeatedly. Therefore, it can be concluded that the existence of cell reformation on the basis of yolk granules according to the dynamic morphological changes is an objective reality.