Benzyl 3-dehydr­oxy-1,2,5-oxadiazolo[3′,4′:2,3]oleanolate

The title compound, C37H50N2O3, is a benzyl ester derivative of oleanolic acid, a penta­cyclic triterpene, with a five-membered oxadiazole ring fused to the ring A. The triterpene A and C rings adopt slightly distorted half-chair conformations, whereas the remaining three six-membered rings are in chair forms

Mechanism of Klebsiella pneumoniae resistance to carbapenem antibiotics

Purpose: To investigate the mechanism of action of Klebsiella pneumoniae (Kpn) resistance to carbapenem. Methods: The susceptibility of six Klebsiella pneumoniae strains to antibiotics was determined using KB assay. Six isolated strains which were resistant to carbapenem were identified and collected using modified Hodge test. The phenotypes of metal enzyme were evaluated by ethylene diamine tetraacetic acid (EDTA) disk diffusion method. The genes for beta-lactamases, including KPC gene, were examined. Results: The six carbapenem-resistant strains of Klebsiella pneumoniae were resistant to imipenem, meropenem and aztreonam, but were sensitive to amikacin, fosfomycin, minocycline, and polymyxin. The six pathogens did not produce metal enzyme, but they produced carbapenemases. Moreover, the six strains partially carried blaTEM or blaSHV gene, but all had blaKPC-2 gene. Conclusion: These results suggest that the pathogens that contain blaKPC-2 gene may be involved in the mechanism of Klebsiella pneumoniae (Kpn) resistance to carbapenem

CSPM: A Contrastive Spatiotemporal Preference Model for CTR Prediction in On-Demand Food Delivery Services

Click-through rate (CTR) prediction is a crucial task in the context of an online on-demand food delivery (OFD) platform for precisely estimating the probability of a user clicking on food items. Unlike universal e-commerce platforms such as Taobao and Amazon, user behaviors and interests on the OFD platform are more location and time-sensitive due to limited delivery ranges and regional commodity supplies. However, existing CTR prediction algorithms in OFD scenarios concentrate on capturing interest from historical behavior sequences, which fails to effectively model the complex spatiotemporal information within features, leading to poor performance. To address this challenge, this paper introduces the Contrastive Sres under different search states using three modules: contrastive spatiotemporal representation learning (CSRL), spatiotemporal preference extractor (StPE), and spatiotemporal information filter (StIF). CSRL utilizes a contrastive learning framework to generate a spatiotemporal activation representation (SAR) for the search action. StPE employs SAR to activate users' diverse preferences related to location and time from the historical behavior sequence field, using a multi-head attention mechanism. StIF incorporates SAR into a gating network to automatically capture important features with latent spatiotemporal effects. Extensive experiments conducted on two large-scale industrial datasets demonstrate the state-of-the-art performance of CSPM. Notably, CSPM has been successfully deployed in Alibaba's online OFD platform Ele.me, resulting in a significant 0.88% lift in CTR, which has substantial business implications

Effect of dexmedetomidine on blood T cell proliferation, T cell subsets and phagocytic function of alveolar macrophages in young rats subjected to splenectomy

Purpose: To study the effect of dexmedetomidine on blood T cell proliferation, T cell subsets and phagocytosis of alveolar macrophages in young rats undergoing splenectomy. Methods: Fifty-four healthy male rats were used for the establishment of an animal model of splenectomy. The young rats were randomly assigned to control, model (untreated) and medication groups, each with 18 rats. The rats in the control and model groups were given physiological saline at a dose of 10 ml/kg, while those in the treatment group were injected with dexmedetomidine at a dose of 50 µg/kg. All treatments were given intraperitoneally (i.p.). T cell proliferation, T cell subset level, phagocytic index and degree of phagocytosis of alveolar macrophages were compared among the rat groups. Results: Relative to control, CD4+, CD8+ and CD4+/CD8+ levels in model and medication groups decreased significantly (p < 0.05). CD4+ and CD8+ levels were lower in the medication group than in model group. Phagocytic index and degree of phagocytosis of alveolar macrophages in model and medication groups were significantly lower than those in the control group, while phagocytic index and degree of phagocytosis of alveolar macrophages in the medication group of rats were smaller than those in model rats (p < 0.05). Conclusion: Dexmedetomidine significantly reduces immune function in splenectomy rats. However, it should be used with caution in patients with splenectomy

Structural reconstruction of the catalytic center of LiPDF through multiple scattering calculation with MXAN

Abstract Peptide deformylase (PDF, EC 3.5.1.27) is essential for the normal growth of eubacterium but not for mammalians. Recently, PDF has been studied as a target for new antibiotics. In this paper, X-ray absorption spectroscopy was employed to determine the local structure around the zinc ion of PDF from Leptospira Interrogans in dry powder, because it is very difficult to obtain the crystallized sample of Li PDF. We performed X-ray absorption near edge structure (XANES) calculation and reconstructed successfully the local geometry of the active center, and the results from calculations show that a water molecule (Wat1) has moved towards the zinc ion and lies in the distance range to coordinate with the zinc ion weakly. In addition, the sensitivity of theoretical spectra to the different ligand bodies was evaluated in terms of goodness-of-fit