A regioselectivity switch in Pd-catalyzed hydroallylation of alkynes.

By exploiting the reactivity of a vinyl-Pd species, we control the regioselectivity in hydroallylation of alkynes under Pd-hydride catalysis. A monophosphine ligand and carboxylic acid combination promotes 1,5-dienes through a pathway involving isomerization of alkynes to allenes. In contrast, a bisphosphine ligand and copper cocatalyst favor 1,4-dienes via a mechanism that involves transmetalation. Our study highlights how to access different isomers by diverting a common organometallic intermediate

Generalized Category Discovery with Decoupled Prototypical Network

Generalized Category Discovery (GCD) aims to recognize both known and novel categories from a set of unlabeled data, based on another dataset labeled with only known categories. Without considering differences between known and novel categories, current methods learn about them in a coupled manner, which can hurt model's generalization and discriminative ability. Furthermore, the coupled training approach prevents these models transferring category-specific knowledge explicitly from labeled data to unlabeled data, which can lose high-level semantic information and impair model performance. To mitigate above limitations, we present a novel model called Decoupled Prototypical Network (DPN). By formulating a bipartite matching problem for category prototypes, DPN can not only decouple known and novel categories to achieve different training targets effectively, but also align known categories in labeled and unlabeled data to transfer category-specific knowledge explicitly and capture high-level semantics. Furthermore, DPN can learn more discriminative features for both known and novel categories through our proposed Semantic-aware Prototypical Learning (SPL). Besides capturing meaningful semantic information, SPL can also alleviate the noise of hard pseudo labels through semantic-weighted soft assignment. Extensive experiments show that DPN outperforms state-of-the-art models by a large margin on all evaluation metrics across multiple benchmark datasets. Code and data are available at https://github.com/Lackel/DPN.Comment: Accepted by AAAI 202

Synthetic Polypeptide Derived from Viral Macrophage Inflammatory Protein II Inhibit VEGF Production of Human Glioma U87 Cells through SDF-1α/CXCR4-Mediated AKT Signaling Pathway

Purpose: To evaluate the effect of synthetic polypeptide (N15P) derived from viral macrophage inflammatory protein II (vMIP-II) on the secretion of vascular endothelial growth factor (VEGF) as well as investigate the signaling pathways involved in stromal cell-derived factor-1α(SDF-1α)/CXC Chemokin Receptor 4 (CXCR4) axis-induced VEGF in glioblastoma U87 cells.Methods: Glioblastoma U87 cells were exposed to SDF-1á, N15P with various concentrations. The expression of CXCR4, SDF-1α and VEGF mRNA were assessed by RT-PCR, while expression level of VEGF was tested by ELISA and protein kinase B (Akt) phosphorylation detected by Western blot.Results: The results showed that CXCR4, SDF-1α, VEGF are expressed in human glioblastoma U87 cell lines. SDF-1α caused a dose-dependent sensitivity of cell proliferation with a maximum effect at 15 µmole/ml, while N15P decreased cell viability in U87 cells in a dose-dependent manner. SDF-1α stimulated the activation of VEGF, and N15P inhibited the activation of VEGF with or without SDF-1α stimulation. VEGF production in U87 cells was associated with Akt pathway. These changes in intracellular processes were blocked by N15P in a dose-dependent manner.Conclusion: The results suggest that N15P suppress SDF-1α/CXCR4  Mediated VEGF production through Akt signaling pathway and this may be a potent therapeutic strategy in glioblastoma.Keywords: Viral macrophage, Inflammatory protein II, Glioblastoma, CXC chemokin receptor 4, Stromal cell-derived factor-1α, Protein kinase

Principle Study of a Semi-active Inerter Featuring Magnetorheological Effect

Inerters are two-terminal mass elements in which the forces applied at the terminals are proportional to relative acceleration between the nodes. The volume and weight of inerters are much smaller than those of any conventional mass element for the same force, which is beneficial for engineering applications. The inerter in mechanical systems corresponds completely to the capacitor in electrical systems, which makes it more convenient to do related investigations based on mechanical-electrical analogies. A semi-active inerter (SAI) featuring a magnetorheological (MR) effect with tunable inertance is proposed, designed, and investigated to enhance the performance of the passive inerters. The proposed SAI consists of a flywheel, a flywheel housing, a ball screw, a connection sleeve, bearings, upper and lower covers, excitation coils, and MR fluid. MR fluid fulfilled in the flywheel housing of the SAI is energized by the excitation coils with applied current, and correspondingly the mechanical characteristics of the SAI are tunable via the applied current. The mathematical model and the mechanical performance of the SAI are established and tested, respectively. The nonlinearity of the experimental results is analyzed and the non-linear model of the SAI is further established. The preliminary principle verification of the continuous adjustment of the equivalent inertance of the SAI is conducted using the non-linear model. Moreover, a compensator is proposed to address the problem of the phase difference between the controllable force and the real output force of the SAI, and continuous inertance adjustment of the SAI with a compensator is realized

Synthetic Polypeptide Derived from Viral Macrophage Inflammatory Protein II Inhibit the Uninfected CD4+ T Cells Apoptosis Induced by HIV-1 Extracellular Nef

Purpose: To evaluate the potential role and cellular mechanism of the CXCR4 antagonist (N15P) derived from the N-terminal of viral macrophage inflammatory protein-II (vMIP-II) on the apoptosis induced by HIV-1 extracellular nef protein in vitro.Method: Peripheral blood mononuclear cells (PBMCs) and Jurkat cells were treated with HIV-1 nef protein alone or together with N15P at different doses and time points. The competitive binding effect of N15P against nef was assessed via radioligand binding assays. Apoptosis was evaluated via terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling (TUNEL) assay. The level of nuclear FOXO3a and phospho-FOXO3a was assessed by Western blotting.Results: The interaction of 125I-nef with Jurkat cells was inhibited by N15P in a dose-dependent manner, with IC50 value of 0.3516 ng/ml. N15P protect against nef protein-induced apoptosis in a timeand concentration- dependent manner. The proapoptotic effect of extracellular nef protein in cells was associated with FOXO3a pathway and the changes in intracellular processes were blocked by N15P in a dose-dependent manner.Conclusion: N15P inhibits the apoptosis of uninfected CD4+ T lymphocytes induced by HIV-1 extracellular nef protein. Therefore, N15P is a potential effective CXCR4 antagonist in the course of HIV and could prevent or delay the onset of AIDS.Keywords: HIV-1, Nef, vMIP-II, Bystander lymphocytes, Apoptosis, FOXO3a, CXCR4 antagonist, Macrophage, Inflammatio