578 research outputs found

    On the Synthesis of Isomeric Dithiophene Analogues of Phenathridine- N-oxides

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    Six of nine o,o\u27-formylnitrobithienyls have been synthesized by the tetrakis(triphenylphosphine)palladium(O)-catalyzed coupling of the three o-bromonitrothiophenes with two of the three o-formylthiopheneboronic acids with sodium carbonate or sodium bicarbonate as base and an ethylene glycol dimethyl ether-water mixture as solvent. In the reaction with 3-formyl-2-thiopheneboronic acid, the coupling was carried out by using triethylamine as base and N,N-dimethylformamide as solvent in an attempt to avoid the facile deboronation of 3-formyl-2-thiopheneboronic acid, but without success. Reduction of the o,o\u27-formylnitrobithienyls gave high yields of the N-oxides of the six isomeric dithienopyridines, which are analogues of phenanthridine-N-oxide. A direct synthesis of one of the dithienopyridines, dithieno[2,3-c:2\u27,3\u27-c]-pyridine, was achieved by the palladium(O)-catalyzed coupling of 2,3-dibromothiophene with 2-formyl-3-thiopheneboranic acid to 3-bromo-2\u27-formyl-2,3\u27- -bithienyl, which was transformed to the 3-azido-2\u27-formyl-2,3\u27- -bithienyl, which upon reduction with hydrogen sulfide underwent ring closure to the phenanthridine analogue

    Fuzzy Multi-Objectives Topology Optimization of Slider Pallet in the Picking Machine of Camellia Fruit

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    In order to improve the dynamic characteristics of the slider pallet in the camellia fruit picking machine under the traditional empirical design and to lighten the weight, a fuzzy multi-objective topology optimization design method was proposed. In this paper, a static and dynamic topology optimization mathematical model was constructed by the compromise programming method, and the weight coefficients of each sub-objective were dynamically assigned by the fuzzy satisfaction variable weight coefficient method, and then the fuzzy multi-objective topology optimization design of the slider pallet for bending condition, bending-torsional complex condition, inertia condition and the first three orders of dynamic frequency was performed. The optimization results showed that the weight of the optimized slider pallet was reduced by 19.4%, and the first-order modal frequency was increased by 5.0%, second order modal frequency increased by 6.6%, third order modal frequency increased by 8.2%; the maximum deformation and maximum stress were increased, but still met the design requirements

    Where to Go Next for Recommender Systems? ID- vs. Modality-based Recommender Models Revisited

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    Recommendation models that utilize unique identities (IDs) to represent distinct users and items have been state-of-the-art (SOTA) and dominated the recommender systems (RS) literature for over a decade. Meanwhile, the pre-trained modality encoders, such as BERT and ViT, have become increasingly powerful in modeling the raw modality features of an item, such as text and images. Given this, a natural question arises: can a purely modality-based recommendation model (MoRec) outperforms or matches a pure ID-based model (IDRec) by replacing the itemID embedding with a SOTA modality encoder? In fact, this question was answered ten years ago when IDRec beats MoRec by a strong margin in both recommendation accuracy and efficiency. We aim to revisit this `old' question and systematically study MoRec from several aspects. Specifically, we study several sub-questions: (i) which recommendation paradigm, MoRec or IDRec, performs better in practical scenarios, especially in the general setting and warm item scenarios where IDRec has a strong advantage? does this hold for items with different modality features? (ii) can the latest technical advances from other communities (i.e., natural language processing and computer vision) translate into accuracy improvement for MoRec? (iii) how to effectively utilize item modality representation, can we use it directly or do we have to adjust it with new data? (iv) are there some key challenges for MoRec to be solved in practical applications? To answer them, we conduct rigorous experiments for item recommendations with two popular modalities, i.e., text and vision. We provide the first empirical evidence that MoRec is already comparable to its IDRec counterpart with an expensive end-to-end training method, even for warm item recommendation. Our results potentially imply that the dominance of IDRec in the RS field may be greatly challenged in the future

    Effects of fertilizer application schemes and soil environmental factors on nitrous oxide emission fluxes in a rice-wheat cropping system, east China

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    Nitrous oxide (N2O) is a potent greenhouse gas (GHG) with agricultural soils representing its largest anthropogenic source. However, the mechanisms involved in the N2O emission and factors affecting N2O emission fluxes in response to various nitrogenous fertilizer applications remain uncertain. We conducted a four-year (2012–2015) field experiment to assess how fertilization scheme impacts N2O emissions from a rice-wheat cropping system in eastern China. The fertilizer treatments included Control (CK), Conventional fertilizer (CF), CF with shallow-irrigation (CF+SI), CF with deep-irrigation system (CF+DI), Optimized fertilizer (OF), OF with Urease inhibitor (OF+UI), OF with conservation tillage (OF+CT) and Slow-release fertilizer (SRF). N2O emissions were measured by a closed static chamber method. N2O emission fluxes ranged from 0.61 μg m-2 h-1 to 1707 μg m-2 h-1, indicating a significant impact of nitrogen fertilizer and cropping type on N2O emissions. The highest crop yields for wheat (3515–3667 kg ha-1) and rice (8633–8990 kg ha-1) were observed under the SRF and OF+UI treatments with significant reduction in N2O emissions by 16.94–21.20% and 5.55–7.93%, respectively. Our findings suggest that the SRF and OF+UI treatments can be effective in achieving maximum crop yield and lowering N2O emissions for the rice-wheat cropping system in eastern China

    Apelin protects auditory cells from cisplatin-induced toxicity in vitro by inhibiting ROS and apoptosis

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    Apelin, a specific endogenous ligand of the G protein-coupled receptor APJ, suppresses oxidative stress and apoptosis in vitro and in vivo. The current study explored whether Apelin protects against toxicity induced by the anticancer drug cisplatin in vitro, and the possible mechanisms that underlie this protective effect. The results showed that Apelin was expressed in the mouse auditory cell line HEI-OC1 and in cochlear hair cells (HCs) and was significantly downregulated by cisplatin, whereas pre-treatment with exogenous Apelin significantly reduced cisplatin-induced apoptosis, and thus protected HEI-OC1 cells and cochlear HCs from cisplatin-induced injury. Furthermore, Apelin reduced reactive oxygen species (ROS) generation, rescued mitochondrial membrane potential disruption, inhibited JNK signaling and attenuated the expression of pro-apoptotic factors in HEI-OC1 cells and in cochlear explants treated with cisplatin. Our findings suggest that Apelin could be used as an otoprotective agent for the prevention of cisplatin-induced ototoxicity

    PINCH1 Is Transcriptional Regulator in Podocytes That Interacts with WT1 and Represses Podocalyxin Expression

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    Background: PINCH1, an adaptor protein containing five LIM domains, plays an important role in regulating the integrin-mediated cell adhesion, migration and epithelial-mesenchymal transition. PINCH1 is induced in the fibrotic kidney after injury, and it primarily localizes at the sites of focal adhesion. Whether it can translocate to the nucleus and directly participate in gene regulation is completely unknown. Methodology/Principal Findings: Using cultured glomerular podocytes as a model system, we show that PINCH1 expression was induced by TGF-β1, a fibrogenic cytokine that promotes podocyte dysfunction. Interestingly, increased PINCH1 not only localized at the sites of focal adhesions, but also underwent nuclear translocation after TGF-β1 stimulation. This nuclear translocation of PINCH1 was apparently dependent on the putative nuclear export/localization signals (NES/NLS) at its C-terminus, as deletion or site-directed mutations abolished its nuclear shuttling. Co-immunoprecipitation and pull-down experiments revealed that PINCH1 interacted with Wilms tumor 1 protein (WT1), a nuclear transcription factor that is essential for regulating podocyte-specific gene expression in adult kidney. Interaction of PINCH1 and WT1 was mediated by the LIM1 domain of PINCH1 and C-terminal zinc-finger domain of WT1, which led to the suppression of the WT1-mediated podocalyxin expression in podocytes. PINCH1 also repressed podocalyxin gene transcription in a promoter-luciferase reporter assay. Conclusion/Significance: These results indicate that PINCH1 can shuttle into the nucleus from cytoplasm in podocytes, wherein it interacts with WT1 and suppresses podocyte-specific gene expression. Our studies reveal a previously unrecognized, novel function of PINCH1, in which it acts as a transcriptional regulator through controlling specific gene expression. © 2011 Wang et al
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