105 research outputs found
Chlorine and Bromine Isotope Fractionation of Halogenated Organic Pollutants on Gas Chromatography Columns
Compound-specific chlorine/bromine isotope analysis (CSIA-Cl/Br) has become a
useful approach for degradation pathway investigation and source appointment of
halogenated organic pollutants (HOPs). CSIA-Cl/Br is usually conducted by gas
chromatography-mass spectrometry (GC-MS), which could be negatively impacted by
chlorine and bromine isotope fractionation of HOPs on GC columns. In this
study, 31 organochlorines and 4 organobromines were systematically investigated
in terms of Cl/Br isotope fractionation on GC columns using GC-double focus
magnetic-sector high resolution MS (GC-DFS-HRMS). On-column chlorine/bromine
isotope fractionation behaviors of the HOPs were explored, presenting various
isotope fractionation modes and extents. Twenty-nine HOPs exhibited inverse
isotope fractionation, and only polychlorinated biphenyl-138 (PCB-138) and
PCB-153 presented normal isotope fractionation. And no observable isotope
fractionation was found for the rest four HOPs, i.e., PCB-101,
1,2,3,7,8-pentachlorodibenzofuran, PCB-180 and 2,3,7,8-tetrachlorodibenzofuran.
The isotope fractionation extents of different HOPs varied from below the
observable threshold (0.50%) to 7.31% (PCB-18). The mechanisms of the on-column
chlorine/bromine isotope fractionation were tentatively interpreted with the
Craig-Gordon model and a modified two-film model. Inverse isotope effects and
normal isotope effects might contribute to the total isotope effects together
and thus determine the isotope fractionation directions and extents. Proposals
derived from the main results of this study for CSIA-Cl/Br research were
provided for improving the precision and accuracy of CSIA-Cl/Br results. The
findings of this study will shed light on the development of CSIA-Cl/Br methods
using GC-MS techniques, and help to implement the research using CSIA-Cl/Br to
investigate the environmental behaviors and pollution sources of HOPs.Comment: 30 pages, 5 figure
34. 上肢のentrapment neuropathy手術例について(第520回千葉医学会例会 整形外科例会)
<p>No.8 nozzle assembly; flow rate 15 L/s; ambient pressure 30 MPa; ambient temperature = jet temperature = 373 K. In cross sections, dimensionless radius is the distance from the inner wall to the measure point divided by the total length between inner and outer wall. The tangential velocity has large gradients near both sides of inner and outer walls.</p
Point-Bind & Point-LLM: Aligning Point Cloud with Multi-modality for 3D Understanding, Generation, and Instruction Following
We introduce Point-Bind, a 3D multi-modality model aligning point clouds with
2D image, language, audio, and video. Guided by ImageBind, we construct a joint
embedding space between 3D and multi-modalities, enabling many promising
applications, e.g., any-to-3D generation, 3D embedding arithmetic, and 3D
open-world understanding. On top of this, we further present Point-LLM, the
first 3D large language model (LLM) following 3D multi-modal instructions. By
parameter-efficient fine-tuning techniques, Point-LLM injects the semantics of
Point-Bind into pre-trained LLMs, e.g., LLaMA, which requires no 3D instruction
data, but exhibits superior 3D and multi-modal question-answering capacity. We
hope our work may cast a light on the community for extending 3D point clouds
to multi-modality applications. Code is available at
https://github.com/ZiyuGuo99/Point-Bind_Point-LLM.Comment: Work in progress. Code is available at
https://github.com/ZiyuGuo99/Point-Bind_Point-LL
Photochromic Fluorescent Probe Strategy for the Super-resolution Imaging of Biologically Important Biomarkers
Here, we report a β-galactosidase (β-Gal)-responsive photochromic fluorescent probe, NpG, that was designed to prebind to human serum albumin (HSA) to form the probe/protein hybrid, NpG@HSA. The formation of NpG@HSA led to an increase in fluorescence emission (520 nm) corresponding to the binding of the fluorescent naphthalimide unit with HSA. In addition, this enabled visualization of the spiropyran fluorescence emission in aqueous media. Our probe/protein hybrid approach afforded a unique imaging platform with enhanced cell permeability and solubility that was capable of visualizing the cellular uptake of NpG@HSA before its activation by β-Gal. The β-Gal-mediated cleavage of the galactose unit within the NpG@HSA hybrid resulted in the formation of NpM@HSA and an increase in red fluorescence emission (620 nm). The resultant merocyanine unit was then able to undergo photoisomerization (merocyanine ↔ spiropyran) to facilitate STORM (i.e., stochastic optical reconstruction microscopy) imaging with minimal phototoxicity and excellent photostability/reversibility. Using STORM, NpG@HSA was able to determine the subcellular distribution of β-Gal activity between cell lines with nanoscale precision. We believe that this system represents a versatile imaging platform for the design of photochromic fluorescent probes suitable for illuminating the precise location of disease-specific biomarkers in various cellular processes.</p
Construction of a cross-species cell landscape at single-cell level.
Individual cells are basic units of life. Despite extensive efforts to characterize the cellular heterogeneity of different organisms, cross-species comparisons of landscape dynamics have not been achieved. Here, we applied single-cell RNA sequencing (scRNA-seq) to map organism-level cell landscapes at multiple life stages for mice, zebrafish and Drosophila. By integrating the comprehensive dataset of > 2.6 million single cells, we constructed a cross-species cell landscape and identified signatures and common pathways that changed throughout the life span. We identified structural inflammation and mitochondrial dysfunction as the most common hallmarks of organism aging, and found that pharmacological activation of mitochondrial metabolism alleviated aging phenotypes in mice. The cross-species cell landscape with other published datasets were stored in an integrated online portal-Cell Landscape. Our work provides a valuable resource for studying lineage development, maturation and aging
Chiral profiling of azole antifungals in municipal wastewater and recipient rivers of the Pearl River Delta, China
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