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Muon spin relaxation (μSR) experiments on single crystals of the structurally perfect triangular antiferromagnet YbMgGaO4 indicate the absence of both static long-range magnetic order and spin freezing down to 0.048 K in a zero field. Below 0.4 K, the μ+ spin relaxation rates, which are proportional to the dynamic correlation function of the Yb3+ spins, exhibit temperature-independent plateaus. All these μSR results unequivocally support the formation of a gapless U(1) quantum spin liquid ground state in the triangular antiferromagnet YbMgGaO4. [ABSTRACT FROM AUTHOR]

Nickel(II) complexes with pyrazole-based ligands are widely employed in catalysis of ethylene oligomerization and subsequent Friedel-Crafts alkylation of toluene. We have prepared ten new nickel(II) dibromide complexes with various substituted bis(azolyl)methanes. They have been characterized using ¹H NMR, IR, high resolution mass spectrometry and elemental analysis. The structures of three complexes have been unambiguously established using X-ray diffraction. It was found that these complexes in the presence of Et2AlCl or Et3Al2Cl3 are active both in ethylene oligomerization and Friedel-Crafts alkylation processes (activity up to 3720 kgoligomer·mol[Ni] -1·h-1). The use of Et3Al2Cl3 results in a higher share of alkylated products (up to 60%). Moreover, catalytic systems activated with Et3Al2Cl3 produced small amounts of odd carbon number olefins (up to 0.8%). The Friedel-Crafts alkylation was used as a trap for previously undetected short-chain odd carbon number olefins (C3 and C5). [ABSTRACT FROM AUTHOR]

A polymer pair composed of poly(N-isopropylacrylamide-co-2-hydroxyethyl methacrylate terminated oligo(L-lactide)) (poly(NIPAAm-co-HEMA-OLLA)) graft random copolymer and poly(D-lactide) (PDLA) homopolymer was self-assembled into micelles with a diameter around 100 nm through the stereocomplexation between the OLLA branches of the graft copolymer and the PDLA homopolymer. The specific intermolecular stereocomplexation was considered as the powerful ordered aggregation force in the micelle cores. The shell's component of poly(NIPAAm-co-HEMA) and its thermosensitivity were proved by 1H nuclear magnetic resonance (NMR) and dynamic light scattering (DLS), respectively. The incorporation of PDLA homopolymer into the graft copolymer affected the micelle size and the critical micelle concentration (CMC). The incorporation of even a small quantity (11 wt%) of PDLA into the graft copolymer micelles resulted in a great decrease of the micelle size. For the graft copolymer with low per cent grafting of 18%, the size of the corresponding micelles decreased slightly even if the PDLA content increased up to 33 wt%. For the graft copolymer with high per cent grafting of 58%, with the further increase of PDLA content, the size of the corresponding micelles at first decreased further and then began to increase. The molecular weight of the PDLA did not significantly affect the micelle size. The polymer pair micelles all showed lower CMC than that of the pure graft copolymer micelles. The higher the PDLA content in the polymer pair micelles, the lower the CMC. TEM results showed that the micelles had core-shell structure and that the polymer pair micelles exhibited a higher chain density in the core than that of the pure graft copolymer micelles. [ABSTRACT FROM AUTHOR]

The accumulation of high levels of adenosine in tumors activates A2A and A2B receptors on immune cells and inhibits their ability to suppress tumor growth. Deletion of adenosine A2A receptors (A2AARs) has been reported to activate antitumor T cells, stimulate dendritic cell (DC) function, and inhibit angiogenesis. In this study, we evaluated the effects of intermittent intratumor injection of a nonselective adenosine receptor antagonist, aminophylline (AMO; theophylline ethylenediamine) and, for the first time to our knowledge, a selective A2BAR antagonist, ATL801. AMO and ATL801 slowed the growth of MB49 bladder and 4T1 breast tumors in syngeneic mice and reduced by 85% metastasizes of breast cancer cells from mammary fat to lung. Based on experiments with A2AAR-/- or adenosine A2B receptor-/- mice, the effect of AMO injection was unexpectedly attributed to A2BAR and not to A2AAR blockade. AMO and ATL801 significantly increased tumor levels of IFN-γ and the IFN-inducible chemokine CXCL10, which is a ligand for CXCR3. This was associated with an increase in activated tumor-infiltrating CXCR3+ T cells and a decrease in endothelial cell precursors within tumors. Tumor growth inhibition by AMO or ATL801 was eliminated in CXCR3-/- mice and RAG1-/- mice that lack mature T cells. In RAG1-/- mice, A2BAR deletion enhanced CD86 expression on CD11b- DCs. Bone marrow chimera experiments demonstrated that CXCR3 and A2BAR expression on bone marrow cells is required for the antitumor effects of AMO. The data suggest that blockade of A2BARs enhances DC activation and CXCR3-dependent antitumor responses. [ABSTRACT FROM AUTHOR]

The authors discusses issues related to the preventive chemotherapy with praziquantel advocated by the World Health Organization for the global control of schistosomiasis. They tackle studies that show the effectiveness of preventive chemotherapy in reducing the prevalence and intensity of infection and control morbidity, and concerns on inadequate drug coverage.

Chronic infectious diseases have a substantial impact on the human B cell compartment including a notable expansion of B cells here termed atypical B cells (ABCs). Using unbiased single-cell RNA sequencing (scRNA-seq), we uncovered and characterized heterogeneities in naïve B cell, classical memory B cells, and ABC subsets. We showed remarkably similar transcriptional profiles for ABC clusters in malaria, HIV, and autoimmune diseases and demonstrated that interferon-γ drove the expansion of ABCs in malaria. These observations suggest that ABCs represent a separate B cell lineage with a common inducer that further diversifies and acquires disease-specific characteristics and functions. In malaria, we identified ABC subsets based on isotype expression that differed in expansion in African children and in B cell receptor repertoire characteristics. Of particular interest, IgD + IgM lo and IgD - IgG + ABCs acquired a high antigen affinity threshold for activation, suggesting that ABCs may limit autoimmune responses to low-affinity self-antigens in chronic malaria., (Copyright © 2021 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).)