603 research outputs found
Cultural Collapse and Contemporary Chinese Art
This essay is scripted in Chinese. The hand-written notes (by the beginning and the end of this essay) in the article are notes to the translator (to English) of this article; they are not pertinent to the body of the writing. (Jerry Wu\u2723).https://digital.kenyon.edu/zhoudocs/1149/thumbnail.jp
Experimental study on a solar-powered thermochemical sorption refrigeration system using strontium chloride/EG-ammonia working pair
An experimental intermittent thermochemical refrigeration system using strontium chloride (SrCl2)–ammonia reaction is described, which mainly consists of an adsorption bed and an evaporator/condenser. The strontium chloride is used as solid absorbent and ammonia as refrigerant. A kind of consolidated composite material based on expanded graphite and strontium chloride is developed firstly, then the composite material is filled into the adsorption bed. The process of desorption or regeneration of strontium chloride is driven by solar energy, and the temperature range of the heating fluid is from 90 to 110℃, which can be heated by solar energy collected by low cost solar flat plate collectors. In the evaporation–absorption process, the evaporating temperature is between -10 and -35℃. The theoretical analysis shows that this refrigeration system is technical feasibility
C2FTrans: Coarse-to-Fine Transformers for Medical Image Segmentation
Convolutional neural networks (CNN), the most prevailing architecture for
deep-learning based medical image analysis, are still functionally limited by
their intrinsic inductive biases and inadequate receptive fields. Transformer,
born to address this issue, has drawn explosive attention in natural language
processing and computer vision due to its remarkable ability in capturing
long-range dependency. However, most recent transformer-based methods for
medical image segmentation directly apply vanilla transformers as an auxiliary
module in CNN-based methods, resulting in severe detail loss due to the rigid
patch partitioning scheme in transformers. To address this problem, we propose
C2FTrans, a novel multi-scale architecture that formulates medical image
segmentation as a coarse-to-fine procedure. C2FTrans mainly consists of a
cross-scale global transformer (CGT) which addresses local contextual
similarity in CNN and a boundary-aware local transformer (BLT) which overcomes
boundary uncertainty brought by rigid patch partitioning in transformers.
Specifically, CGT builds global dependency across three different small-scale
feature maps to obtain rich global semantic features with an acceptable
computational cost, while BLT captures mid-range dependency by adaptively
generating windows around boundaries under the guidance of entropy to reduce
computational complexity and minimize detail loss based on large-scale feature
maps. Extensive experimental results on three public datasets demonstrate the
superior performance of C2FTrans against state-of-the-art CNN-based and
transformer-based methods with fewer parameters and lower FLOPs. We believe the
design of C2FTrans would further inspire future work on developing efficient
and lightweight transformers for medical image segmentation. The source code of
this paper is publicly available at https://github.com/xianlin7/C2FTrans
Development of small interfering RNA delivery system using PEI-PEG-APRPG polymer for antiangiogenic vascular endothelial growth factor tumor-targeted therapy
Zong-Xia Lu1, Li-Ting Liu1,2, Xian-Rong Qi11Department of Pharmaceutics, School of Pharmaceutical Sciences, Peking University, Beijing, People's Republic of China; 2Department of Pharmacy, School and Hospital of Stomatology, Peking University, Beijing, People's Republic of ChinaBackground: Small interfering RNA (siRNA) can silence target genes in the cytoplasm and be a major tool in gene therapy. Vascular endothelial growth factor (VEGF), a potent regulator of angiogenesis, is overexpressed in most tumors and is closely associated with tumor growth and metastasis. It has been shown that inhibition of VEGF expression by siRNA is an effective and useful method for antiangiogenic tumor therapy.Methods: In the present study, we synthesized a targeted delivery system of PEI-PEG-APRPG incorporating angiogenic vessel-homing Ala-Pro-Arg-Pro-Gly (APRPG) peptide into cationic polyethylenimine (PEI) via a hydrophilic poly(ethylene glycol) (PEG) spacer.Results: PEI-PEG-APRPG effectively condensed siRNA into 20–50 nm nanoparticles with a positive surface charge using a suitable N/P ratio. The siRNA/PEI-PEG-APRPG complex effectively enhanced the stability of siRNA in RNase A, and improved the proliferation-inhibiting ability and transfection efficiency of siRNA in vitro and tumor accumulation in vivo. In addition, the siRNA/PEI-PEG-APRPG complex exhibited high efficiency as antitumor therapy with regard to tumor growth, microvessel density, and VEGF protein and mRNA levels.Conclusion: These findings suggest that PEI-PEG-APRPG effectively delivers siRNA to tumors overexpressing VEGF and thereby inhibits tumor growth.Keywords: PEI-PEG-APRPG, VEGF siRNA, gene delivery, tumor-targeted, antiangiogenic therap
Network pharmacology and UPLC-Q-TOF/MS studies on the anti-arthritic mechanism of Pterocephalus hookeri
Purpose: To investigate the mechanism underlying the anti-arthritic properties of Pterocephalus hookeri used for treatment of rheumatoid arthritis (RA).Methods: Aqueous methanol extract of P. hookeri was analyzed using UPLC-Q-TOF/MS, a Waters Acquity UPLCR BEH C18 column (2.1 × 100 mm, 1.7 μm) and gradient elution with acetonitrile-formic acid-water. Targets and related pathways were predicted by PharmMapper database and Molecule Annotation System, respectively. The network was built with Cytoscape software.Results: Forty compounds were identified, comprising 17 iridoid glycosides, 7 phenolic acids, 13 triterpenes, and 3 other compounds. A total of 38 targets and 44 pathways associated with RA were obtained. These involved mainly MAPK signaling pathway, adherens junction, and colorectal cancer.Conclusion: These results from network pharmacology suggest that P. hookeri exerts therapeutic effect on RA via multiple components, multiple targets and multiple pathways.Keywords: Pterocephalus hookeri, Rheumatoid arthritis, UPLC-Q-TOF/MS, Chemical composition, Network pharmacolog
Triggers of Permo-Triassic boundary mass extinction in South China: the Siberian Traps or Paleo-Tethys ignimbrite flare-up?
(Methanol-κO)bis{2-methoxy-6-[(4-methylphenyl)iminiomethyl]phenolato-κ2 O,O′}tris(nitrato-κ2 O,O′)lanthanum(III)
The asymmetric unit of title compound, [La(NO3)3(C15H15NO2)2(CH3OH)], consists of two Schiff base 2-methoxy-6-[(4-methylphenyl)iminiomethyl]phenolato (HL) ligands, three independent nitrate anions and one methanol molecule coordinated to LaIII. The coordination environment of the LaIII ion is formed by eleven O atoms. Three bidentate nitrate anions coordinate to the LaIII ion, while two HL ligands chelate the metal center with O atoms from the phenolate and methoxy groups. The HL ligands are zwitterionic, with protonated imine N atoms. The coordination sphere is completed by one methanol molecule. The protonated imine N atoms are involved in intramolecular N—H⋯O hydrogen bonds with the phenoxy groups and nitrate ligands. One O atom of one nitrate group is disordered over two sites of equal occupancy
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