Abstract: This application provides methods and compositions related to constructing nucleic acid hydrogels (e.g., RNA hydrogels) having repetitive monomer units, each monomer unit includes one or more G-quadruplex sequences. These G-quadruplex sequences cross-link the nucleic acid concatemer such that it self-assembles into a hydrogel under appropriate conditions. In some embodiments, each monomeric unit of the nucleic acid concatemer comprises a coding sequence for polypeptide of interest; and the nucleic acid hydrogel formed by the nucleic acid concatemer can be used for expressing the polypeptide in high quantities. In some embodiments, at least two RNA concatemers comprising G-quadruplex sequences are produced, one further comprising a spacer and the other further comprising a sequence encoding a polypeptide of interest. These two RNA concatemers are combined and self assembled to form a single, wideband RNA hydrogel.

Abstract: A memory card changer is disclosed. The memory card changer can include a connection unit, which interchanges the data with the host device, a slot unit, which attaches and detaches a plurality of memory cards and a processing unit, which controls the host device to recognize individual storage capacities of the memory cards individually or collectively, in which each of the plurality of memory cards have been inserted in the slot unit. The memory card changer of the present invention can use the plurality of memory cards having smaller storage capacities as memory of large capacity.