Zhikuan Zhang

The coronavirus membrane protein (M) is the most abundant viral structural protein and plays a central role in virus assembly and morphogenesis. However, the process of M protein-driven virus assembly are largely unknown. Here, we report the cryo-electron microscopy structure of the SARS-CoV-2 M protein in two different conformations. M protein forms a mushroom-shaped dimer, composed of two transmembrane domain-swapped three-helix bundles and two intravirion domains. M protein further assembles

Toll-like receptor 7 (TLR7) is an innate immune receptor for single-stranded RNA (ssRNA) and has important roles in infectious diseases. We previously reported that TLR7 shows synergistic activation in response to two ligands, guanosine and ssRNA. However, the specific ssRNA sequence preference, detailed recognition mode of TLR7 and its ligand, and molecular determinants of TLR7 and TLR8 selectivity remain unknown. Here, we report on TLR7 from a large-scale crystallographic study combined with a

In this letter, a self-aligned recessed source/drain (ReS/D) ultrathin body (UTB) silicon-on-insulator (SOI) MOS technology is proposed and demonstrated. The thick diffusion regions of ReS/D are placed on a recessed trench, which is patterned on the buried oxide and go under the SOI film. The new structure reduces the parasitic S/D resistance without increasing the gate-to-drain Miller capacitance, which is the major advantage over the elevated S/D structure. Fabrication details and experimental

The history of mankind has been plagued by the tug of war with viral infections. Toll-like receptors (TLRs) and other receptors of the innate immune system constitute an early defense system against invading viruses by recognizing the viral genetic material, the nucleic acids (NAs). Agonistic ligands of NA-sensing TLRs play an emerging role in the treatment of viral diseases, demonstrating a crucial role of these receptors. Recently, crystal structures have afforded new insights into TLR recogni

The high-affinity immunoglobulin E (IgE) receptor (FcεRI) drives type I hypersensitivity in response to allergen-specific IgE. FcεRI is a multimeric complex typically composed of one α, one β, and two disulfide-linked γ subunits. The α subunit binds to the fragment crystallizable (Fc) region of IgE (Fcε), whereas the β and γ subunits mediate signaling through their intracellular immunoreceptor tyrosine-based activation motifs (ITAMs). Here, we report cryo-electron microscopy (cryo-EM) structures

The advantages of using elevated S/D formed on oxide shallow trench isolation are studied in detail. By careful design, the short channel short channel effects can be suppressed by the elevated source/drain (S/D) structure. In addition, the S/D region parasitic capacitance is significantly suppressed by the silicon-on-insulator (SOI)-like S/D structure. Tradeoff between series resistance and gate-to-drain Miller capacitance can be achieved by carefully selecting the gate spacer thickness. With c

In this work, a self-aligned recessed source/drain (ReS/D) ultra-thin body (UTB) SOI MOS technology is proposed and demonstrated. The thick diffusion regions of the ReS/D are placed on a recessed trench, which is patterned on the buried oxide and go under the SOI film. The new structure reduces the parasitic source/drain resistance without increasing the gate-to-drain Miller capacitance, which is the major advantage over the elevated source/drain structure. The scalability of the UTB MOSFETs and

As MOSFET feature sizes are scaled to the deep sub-0.1 /spl mu/m regime, ultra-shallow source/drain extensions and heavily doped halos are required to suppress short-channel effects. These structures result in high series resistance and parasitic capacitance. A source/drain-on-insulator (SDOI) structure with elevated source/drain combined with an oxide isolation, formed by a shallow trench process underneath the source/drain region, is reported to be a potential solution to simultaneously reduce

The effects of grain boundaries on the performance of super TFTs formed by MILC are studied. The existence of grain boundaries in the channel region will cause subthreshold hump, early punchthrough or device degradation, depending on the direction of the grain boundaries. The probability for the channel region of a TFT to cover multiple grains decrease significantly when the device is scaled down, thus resulting in better device performance and higher uniformity. A novel method to measure the gr

Source/drain engineering for extremely scaled MOSFETs by Zhikuan Zhang thesis 2005 xi, 133 leaves : ill. ; 30 cm As MOSFET feature sizes are scaled down to the deep sub-tenth micron regime, serious degradation of MOSFET device performance due to…Read more ›