Augmented reality (AR) devices, as smart glasses, enable users to see both the real world and virtual images simultaneously, contributing to an immersive experience in interactions and visualization. ...Recently, to reduce the size and weight of smart glasses, waveguides incorporating holographic optical elements in the form of advanced grating structures have been utilized to provide light-weight solutions instead of bulky helmet-type headsets. However current waveguide displays often have limited display resolution, efficiency and field-of-view, with complex multi-step fabrication processes of lower yield. In addition, current AR displays often have vergence-accommodation conflict in the augmented and virtual images, resulting in focusing-visual fatigue and eye strain. Here we report metasurface optical elements designed and experimentally implemented as a platform solution to overcome these limitations. Through careful dispersion control in the excited propagation and diffraction modes, we design and implement our high-resolution full-color prototype, via the combination of analytical-numerical simulations, nanofabrication and device measurements. With the metasurface control of the light propagation, our prototype device achieves a 1080-pixel resolution, a field-of-view more than 40°, an overall input-output efficiency more than 1%, and addresses the vergence-accommodation conflict through our focal-free implementation. Furthermore, our AR waveguide is achieved in a single metasurface-waveguide layer, aiding the scalability and process yield control.
Cavities within proteins that are strictly apolar typically appear to be empty. It has been suggested, however, that water molecules may be present within such cavities but are too disordered to be ...seen in conventional crystallographic analyses. In contrast, it is argued here that solvent mobility will be limited by the size of the cavity and for this reason high‐occupancy solvent in cavities of typical volume should be readily detectable using X‐ray crystallography. Recent experimental studies of cavity hydration are reviewed. Such studies are consistent with theoretical predictions that it is energetically unfavorable to have a single water molecule in an apolar cavity. As apolar cavities become larger, a point is reached where it is favorable to have the cavity occupied by a cluster of mutually H‐bonded water molecules. The exact size of such a cavity in a protein is yet to be verified.
Enzymes BN tricked: High‐resolution protein crystallography indicates that unnatural 1,2‐dihydro‐1,2‐azaborines bind inside the nonpolar cavity of T4 lysozyme L99A (see picture) in a fashion that is ...very similar to the binding of their “natural” all‐carbon isosteres. These studies show that 1,2‐azaborines can serve as boron‐containing, hydrophobic arene mimics in biomedical research.
Informal caregivers (ICs) are forced to make adaptive lifestyle changes to meet the significant demand of caring for loved ones who are terminally ill. Open-ended questions were administered with 26 ...ICs who cared for loved ones diagnosed with terminal illnesses whose prognosis was less than six months. The results add substantive information to parsimonious literature and demonstrate a correlation with existing studies that coincide with the debilitating effects that caregiving has on the informal carer. The study clarifies the complexities of the caregiving role characterized by the involvement that may adversely affect socialization, physical health conditions, and marital dynamics, among other areas of the IC's personal life.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK, VSZLJ
18.
Proteins under pressure Matthews, Brian W.
Proceedings of the National Academy of Sciences - PNAS,
05/2012, Letnik:
109, Številka:
18
Journal Article
Aminopeptidase N from Escherichia coli is a major metalloprotease that participates in the controlled hydrolysis of peptides in the proteolytic pathway. Determination of the 870-aa structure reveals ...that it has four domains similar to the tricorn-interacting factor F3. The thermolysin-like active site is enclosed within a large cavity with a volume of 2,200 ų, which is inaccessible to substrates except for a small opening of approximately 8-10 Å. The substratebased inhibitor bestatin binds to the protein with minimal changes, suggesting that this is the active form of the enzyme. The previously described structure of F3 had three distinct conformations that were described as "closed," "intermediate," and "open." The structure of aminopeptidase N from E. coli, however, is substantially more closed than any of these. Taken together, the results suggest that these proteases, which are involved in intracellular peptide degradation, prevent inadvertent hydrolysis of inappropriate substrates by enclosing the active site within a large cavity. There is also some evidence that the open form of the enzyme, which admits substrates, remains inactive until it adopts the closed form.
E. coli β-galactosidase is a tetramer of four identical 1023-amino acid chains. Each chain consists of five domains, the third of which is an eight-stranded
α
/
β
barrel that comprises much of the ...active site. This site does, however, include elements from other domains and other subunits. The N-terminal region of the polypeptide chains help form one of the subunit interfaces. Taken together these features provide a structural basis for the well-known property of α-complementation. Catalytic activity proceeds via the formation of a covalent galactosyl intermediate with Glu537, and includes ‘shallow’ and ‘deep’ modes of substrate binding.
To cite this article: B.W. Matthews, C. R. Biologies 328 (2005).
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