Direct structure-determination of nodavirus in solution by x-ray ensemble diffraction microscopy

Abstract

The structures of biomacromolecules are conventionally characterized by crystallography and cryogenic electron microscopy . The requirements of sample preparation limit the understanding of the specimens in their native states. Small-angle x-ray scattering (SAXS) has the capability of obtaining structural information from biological specimens in solution. However, resolving the structure from the acquired one-dimensional (1D) diffraction data requires the prior knowledge of the sample, and no unique solution can be guaranteed. Coherent diffraction imaging (CDI) provides excellent uniqueness in 2D/3D phase retrieval while the resolution is restricted by the poor signal-to-noise ratio at high-angle scattering. Here we combine CDI and SAXS to directly image a 19-nm-sized nodavirus particle in solution and determine the core-shell density distribution at a 1.3 nm pixel resolution. With 77,170 diffraction patterns summarized from randomly distributed nodavirus particles, the structural information can be obtained from the diffraction intensity alone without preknowledge. The hollow density distribution of a nodavirus particle revealed by our reconstruction is consistent with the structural determinations from crystallography and cryogenic electron microscopy. We believe this work represents a new protocol for characterizing the structures of macromolecules in solution from accumulated x-ray scattering data.

Development and Evaluation of a Retrieval-Augmented Large Language Model Framework for Ophthalmology

“…The augmentation of LLMs with knowledge bases has been used by other studies as well, which underscores the pivotal role of effective knowledge base utilization. Although GPT-4, with knowledge base assistance, continues to stand as the foremost competitive large model, the support of knowledge base enables other open-source large models to rival the performance of GPT-4 in certain domains, which is consistent with our research findings. However, our study presents several strengths, including a more comprehensive evaluation methodology, reduced computational expenses, and localized deployment to address privacy concerns.…”

“…Although our 13B model necessitates substantial computational resources, its deployment potentially remains viable in health care and research settings, offering effective handling of intricate medical tasks. Recent research has emphasized techniques for enriching LLMs with information sourced from internet searches to furnish clinically tailored responses . However, in our approach, we prioritize precision and extensively use a comprehensive knowledge base to bolster LLMs, thereby elevating medical reliability.…”

Toggling Near‐Field Directionality via Polarization Control of Surface Waves

“…[ 53–59 ] That is, this waveguide in free space only supports TM surface waves if or TE surface waves if . [ 53,59 ] For our proposed geometry, we have for the meta‐based metasurface (Note S1, Supporting Information) and for the doped graphene. Since Im(σ gra ) is sensitive to μ c , the sign of Im(σ total ) can be actively toggled by tuning the chemical potential μ c of graphene.…”

“…In principle, the polarization of surface waves in the graphene‐metasurface waveguide is determined by the sign of Im(σ total ). [ 53–59 ] That is, this waveguide in free space only supports TM surface waves if or TE surface waves if . [ 53,59 ] For our proposed geometry, we have for the meta‐based metasurface (Note S1, Supporting Information) and for the doped graphene.…”

Technical analysis of development of a frequency conversion measurement device for transmission tower grounding resistance

“…When struck by lightning, lightning currents can be introduced into the earth through the grounding system. If the grounding resistance of the transmission tower is too large, a large potential will be generated at some positions of the lightning protection line of the transmission tower, and a counterattack overvoltage will occur, which directly affects the operation safety of the transmission line [2] . To this end, necessary measures need to be taken to reduce the grounding resistance of transmission towers and reduce the occurrence of transmission line operation accidents.…”