Studies toward the total synthesis of armatol F: stereoselective construction of the C6 and C7 stereocenters and formation of the A-ring skeleton

Armatol F, isolated from the red alga Chondria armata as a polyether triterpene, has a solitary oxepane (A-ring) and a fused tricyclic ether moiety (BCD-ring). The A-ring features a rare cis-relationship between the hydroxy group at the quaternary carbon C6 and the carbon chain at C7. As part of our program toward the total synthesis of armatol F, a new stereoselective method for the construction of the C6 and C7 stereocenters has been developed based on chirality-transferring Ireland-Claisen rearrangement. The A-ring skeleton has also been synthesized from the rearrangement product by a process including ring-closing olefin metathesis.     

Intermolecular π‐stacking and F...F interactions of fluorine‐substituted meso‐alkynylporphyrin

Two C2‐symmetric meso‐alkynylporphyrins, namely 5,15‐bis[(4‐butyl‐2,3,5,6‐tetrafluorophenyl)ethynyl]‐10,20‐dipropylporphyrin, C₅₀H₄₂F₈N₄, (I), and 5,15‐bis[(4‐butylphenyl)ethynyl]‐10,20‐dipropylporphyrin, C₅₀H₅₀N₄, (II), show remarkable π–π stacking that forms columns of porphyrin centers. The tetrafluorophenylene moieties in (I) show intermolecular interactions with each other through the F atoms, forming one‐dimensional ribbons. No significant π–π interactions are observed in the plane of the phenylene and tetrafluorophenylene moieties in either (I) or (II). The molecules of both compounds lie about inversion centers.     

Perturbation theory analysis for electronic response of DNA base pairs

The electronic responses of duplex B-DNA sequences are investigated using perturbation theory analyses. The electronic polarizability and effective mass are computed for base pair doublets and triplets and the electronic structures are calculated according to density functional theory. High polarizability and a light effective mass are obtained in a sequence such as 5′-GGG-3′. The results indicate that the concentration of GC base pairs causes a high response of the electronic states, and molecular orbitals that are very responsive to the electric field tend to be reactive with other orbitals or conducting hole carriers. Furthermore, the interaction between the electronic states and a positively charged wavepacket is discussed, assuming hole injection in the DNA sequences. The sequence of 5′-GGG-3′ responds sensitively to the external hole approach, which is presumably injected to a guanine site.     

Fast image enlargement using predefined codebook and eigenspace backprojection for lost pixel

In this paper, a new image enlargement method applying the backprojection for lost pixel (BPLP) to the predefined codebook-based method is proposed. BPLP is a method for image restoration. In BPLP, the eigenspace reflecting the characteristics of an input image is generated from the remained pixels and is used to restore the missing pixels. In the proposed method, the eigenspace is replaced by one generated from the predefined codebook (PDC). PDC represents edge-blurring properties in a small image patch and consists of pairs of low- and high-frequency image patches on various edge patterns. By replacing the PDC-based estimation of lost high-frequency components with BPLP, a fast image enlargement method retaining its performance can be developed. Through some experiments, the effectiveness of the proposed method was demonstrated. Especially, it was confirmed that the processing time of the proposed method was shortened to about 1/50 that of the PDC-based method.     

Limit theorems for the pre-averaged Hayashi–Yoshida estimator with random sampling

We will focus on estimating the integrated covariance of two diffusion processes observed in a nonsynchronous manner. The observation data is contaminated by some noise, which possibly depends on the time and the latent diffusion processes, while the sampling times also possibly depend on the observed processes. In a high-frequency setting, we consider a modified version of the pre-averaged Hayashi–Yoshida estimator, and we show that such a kind of estimator has the consistency and the asymptotic mixed normality, and attains the optimal rate of convergence.     

A Gene-Editable Palladium-Based Bioorthogonal Nanoplatform Facilitates Macrophage Phagocytosis for Tumor Therapy

Macrophage phagocytosis of tumor cells has emerged as an attractive strategy for tumor therapy. Nevertheless, immunosuppressive M2 macrophages in the tumor microenvironment and the high expression of anti-phagocytic signals from tumor cells impede therapeutic efficacy. To address these issues and improve the management of malignant tumors, in this study we developed a gene-editable palladium-based bioorthogonal nanoplatform, consisting of CRISPR/Cas9 gene editing system-linked Pd nanoclusters, and a hyaluronic acid surface layer (HBPdC). This HBPdC nanoplatform exhibited satisfactory tumor-targeting efficiency and triggered Fenton-like reactions in the tumor microenvironment to generate reactive oxygen species for chemodynamic therapy and macrophage M1 polarization, which directly eliminated tumor cells, and stimulated the antitumor response of macrophages. HBPdC could reprogram tumor cells through gene editing to reduce the expression of CD47 and adipocyte plasma membrane-associated protein, thereby promoting their recognition and phagocytosis by macrophages. Moreover, HBPdC induced the activation of sequestered prodrugs via bioorthogonal catalysis, enabling chemotherapy and thereby enhancing tumor cell death. Importantly, the Pd nanoclusters of HBPdC were sufficiently cleared through basic metabolic pathways, confirming their biocompatibility and biosafety. Therefore, by promoting macrophage phagocytosis, the HBPdC system developed herein represents a highly promising antitumor toolset for cancer therapy applications.     

A catalytic enantioselective conjugate addition of cyanide to enones

The first synthetically useful catalytic enantioselective conjugate addition of cyanide to enones is described. The optimized conditions involved a Gd catalyst (5 or 10 mol %) derived from ligands 3 or 4 and a 1:1 ratio of TBSCN and 2,6-dimethylphenol. The reaction exhibited excellent to high enantioselectivity and a wide substrate scope. Moreover, the 1,4-adduct was exclusively produced over the 1,2-adduct. The complete regioselectivity was due both to stabilization of the 1,4-selective silylated polymetallic catalyst (7) using a TBS group and the ability of the asymmetric catalyst to promote retro-cyanation from the 1,2-adduct.     

Baryogenesis in false vacuum

The null result in the LHC may indicate that the standard model is not drastically modified up to very high scales, such as the GUT/string scale. Having this in the mind, we suggest a novel leptogenesis scenario realized in the false vacuum of the Higgs field. If the Higgs field develops a large vacuum expectation value in the early universe, a lepton number violating process is enhanced, which we use for baryogenesis. To demonstrate the scenario, several models are discussed. For example, we show that the observed baryon asymmetry is successfully generated in the standard model with higher-dimensional operators.