A facile method for the rapid and selective deprotection of methoxymethyl (MOM) ethers

We describe a rapid and efficient method for selective deprotection of methoxymethyl (MOM) ethers using ZnBr₂ and n-PrSH, which completely removed MOM from diverse MOM ethers of primary, secondary, and tertiary alcohols or phenol derivatives. The deprotection takes less than ten minutes with both high yield and selectivity in the presence of other protecting groups. In addition, the rapid deprotection of MOM ethers of tertiary hydroxyls in high yield with no epimerization allows MOM to be a suitable protecting group for tertiary alcohols.     

Some Continued Fractions in Ramanujan’s Lost Notebook

In this paper we first give the value of a periodic continued fraction which was recorded incorrectly by Ramanujan on page 341 of his lost notebook. Next, we describe several pairs of equivalent continued fractions in which one is the odd part of the other. One of the results is for the Rogers-Ramanujan continued fraction which was recently proved by Berndt and Yee. Finally, using the Bauer-Muir transformation we prove the equivalence of two continued fractions. One was recorded on page 44 in Ramanujan’s lost notebook, and the other is found in the unorganized pages at the end of Ramanujan’s second notebook.     

Charge-discharge characteristics of nanocrystalline Co3O4 powders via aerosol flame synthesis

Nanocrystalline Co₃O₄ powders were synthesized by aerosol flame synthesis (AFS) method for the anode of lithium ion batteries and the basic electrochemical properties were investigated. The effects of synthesis conditions and heat-treatment temperature on the morphology, crystallite size and electrochemical properties were investigated. As-prepared soot contained Co₃O₄, CoO and Co(OH)₂, which were eventually converted into cubic spinel Co₃O₄ by post heat treatment. The as-prepared particle size was in the range of 10-30 nm and grew to 50-85 nm by the heat treatment. With growing particle size and improved crystallinity, charge-discharge capacity and cycle performance were improved and the discharge capacity of the powder heat-treated at 700 °C was 571 mAh/g after 30 cycles, which was better than Co₃O₄ powder reported in the previous literature.     

Morphological and Structural Evolutions of Metal–Organic Framework Particles from Amorphous Spheres to Crystalline Hexagonal Rods

Compositions as well as morphologies and structures of particles are vital factors that define their properties and applications. However, the morphology and structure changes associated with the composition change of metal–organic frameworks (MOFs) are barely studied. Herein, we report the morphology and structure changes of MOF particles associated with the ratio of two organic linkers incorporated within MOF particles, when they are constructed from the reactions of In(NO₃)₃ in the presence of isophthalic acid (H₂IPA) and/or 1,4‐benzenedicarboxylic acid (H₂BDC). Two tendencies—the tendency of BDC and In³⁺ to form porous crystalline hexagonal rods, and the tendency of IPA and In³⁺ to form non‐porous amorphous spherical particles—compete during the formation of MOF particles. Eventually, the incorporated ratio of BDC and IPA within the MOF particles, and thus their morphology and porosity, are controlled by altering the relative amounts of H₂BDC and H₂IPA used during the reactions.     

Crystal forms of an angiotensin II receptor antagonist BR-A657

The compound BR-A657 is an angiotensin II receptor antagonist. The objective of this work was to investigate the existence of polymorphs and pseudopolymorphs of BR-A657 and the transformation of crystal forms. Three crystal forms of BR-A657 have been isolated by recrystallization and characterized by powder X-ray diffractometry, differential scanning calorimetry, and thermogravimetric analysis. After storage of three days at 0% RH (silica gel, 20°C), 52% RH (saturated solution of Na₂Cr₂O₇·2H₂O/20°C) and 95% RH (saturated solution of Na₂HPO₄/20°C), Forms 2 and 3 were transformed to Form 1.     

An efficient synthesis of ([F]fluoropropyl)quinoline-5,8-diones by rapid radiofluorination-oxidative demethylation

Since many molecules bearing quinoline-5,8-dione or fused 1,4-quinone moieties possess a wide spectrum of biological activities, efficient methods for incorporation of fluorine-18 (F-18) into quinoline-5,8-diones have received considerable attention in positron emission tomography (PET) molecular imaging studies. In this paper, we describe an efficient synthetic route for the regioselective preparation of fluoropropyl-substituted quinoline-5,8-diones on the C3, C4, and C6 positions by tert-alcohol media fluorination, followed by oxidative demethylation of the corresponding dimethoxy compound using N-bromosuccinimide (NBS) in the presence of catalytic amounts of sulfuric acid. Moreover, F-18 labeled [¹⁸F]fluoropropylquinoline-5,8-diones [¹⁸F]21-23 were prepared from the corresponding mesylate precursors by a method of rapid and efficient one-pot, two-step reactions: radiofluorination using TBA [¹⁸F]F generated under no-carrier-added (NCA) conditions; oxidative demethylation, resulting in a 45% radiochemical yield of [¹⁸F]21-23 (decay-corrected) with a total synthesis time (including HPLC purification) of 75 min and high radiochemical purity (>99%), as well as high specific activity (∼230 GBq/μmol).     

The promotion effect of catalytic activity by Ru substitution at the B site of La1−x Sr x Cr1−y Ru y O3−z for propane steam reforming

A series of La_1?x Sr _x Cr_1?y Ru _y O_3?δ (0.1 ≤ x ≤ 0.5, 0.05 ≤ y ≤ 0.15) materials was prepared by the sol–gel method to develop alternative catalysts for propane steam reforming. Catalyst characteristics were evaluated using physicochemical methods including X-ray diffraction, Brunauer–Emmett–Teller methods, H₂ temperature-programmed reduction, and thermogravimetry analysis (TGA). Effects of the amount of ruthenium (Ru) and strontium and the steam-to-carbon ratio (S/C) were investigated. An increase in Ru content led to increased propane conversion and H₂ yield, especially below 700 °C. Dramatic enhancement of catalytic activity was observed with La_0.8Sr_0.2Cr_0.85Ru_0.15O₃ under 600 °C, achieving propane conversion over 79% between 600 and 800 °C with maximum propane conversion and H₂ yield of 98.3% and 63.3%, respectively. Also, good resistance to carbon formation for the La_0.8Sr_0.2Cr_0.85Ru_0.15O₃ catalyst was confirmed by long-term testing and TGA analysis.

     

Ordered complex nanostructures from bimodal self-assemblies of diblock copolymer micelles with solvent annealing

We report the formation of ordered complex nanostructures from single-layered films of mixtures of polystyrene-poly(2-vinylpyridine) (PS-P2VP) and polystyrene-poly(4-vinylpyridine) (PS-P4VP) diblock copolymer micelles by THF (tetrahydrofuran) annealing. We first examined the influence of THF vapor on PS-P2VP and PS-P4VP micelles in their single-layered films. Due to the different solubility of PS-P2VP and PS-P4VP copolymers in THF, a hexagonal array of PS-P2VP micelles was changed into cylindrical nanodomains, but that of PS-P4VP micelles was not changed. The different influence of THF on PS-P2VP and PS-P4VP micelles was combined in single-layered films of mixtures of both micelles. For the purpose, we prepared mixture solutions of independently prepared small PS-P2VP and large PS-P4VP micelles. Then, bimodal self-assemblies of micelles were prepared from the mixtures, for which the hexagonal array of large PS-P4VP micelles was surrounded by small PS-P2VP micelles. When the bimodal self-assembly was annealed by THF vapor, PS-P2VP micelles were transformed into cylindrical nanodomains, but their reorganization was guided by hexagonally arranged PS-P4VP micelles. As a result, we were able to produce ordered complex nanostructures in the form of a hexagonal array of PS-P4VP micelles surrounded by PS-P2VP cylinders, which was further utilized for the synthesis of Au nanoparticles.     

On characterizations of real hypersurface in complex space form with Codazzi type structure Lie operator

In this paper, we prove that if $(\nabla _{X} L_{\xi })Y= (\nabla _{Y} L_{\xi })X$ holds on $M$ , then $M$ is a Hopf hypersurface, where $L_\xi $ denote the induced operator from the Lie derivative with respect to the structure vector field $\xi $ . We characterize such Hopf hypersurfaces of $M_n(c)$ .     

Single-cell analysis of multiple myelomas refines the molecular features of bortezomib treatment responsiveness

Both the tumor and tumor microenvironment (TME) are crucial for pathogenesis and chemotherapy resistance in multiple myeloma (MM). Bortezomib, commonly used for MM treatment, works on both MM and TME cells, but innate and acquired resistance easily develop. By single-cell RNA sequencing (scRNA-seq), we investigated bone marrow aspirates of 18 treatment-naïve MM patients who later received bortezomib-based treatments. Twelve plasma and TME cell types and their subsets were identified. Suboptimal responders (SORs) to bortezomib exhibited higher copy number alteration burdens than optimal responders (ORs). Forty-four differentially expressed genes for SORs based on scRNA-seq data were further analyzed in an independent cohort of 90 treatment-naïve MMs, where 24 genes were validated. A combined model of three clinical variables (older age, low absolute lymphocyte count, and no autologous stem cell transplantation) and 24 genes was associated with bortezomib responsiveness and poor prognosis. In T cells, cytotoxic memory, proliferating, and dysfunctional subsets were significantly enriched in SORs. Moreover, we identified three monocyte subsets associated with bortezomib responsiveness and an MM-specific NK cell trajectory that ended with an MM-specific subset. scRNA-seq predicted the interaction of the GAS6-MERTK, ALCAM-CD6, and BAG6-NCR gene networks. Of note, tumor cells from ORs and SORs were the most prominent sources of ALCAM on effector T cells and BAG6 on NK cells, respectively. Our results indicate that the complicated compositional and molecular changes of both tumor and immune cells in the bone marrow (BM) milieu are important in the development and acquisition of resistance to bortezomib-based treatment of MM.Subject terms: Myeloma, Cancer microenvironment