Aluminum porphyrins with quaternary ammonium halides as catalysts for copolymerization of cyclohexene oxide and CO2: metal–ligand cooperative catalysis

Bifunctional AlIII porphyrins with quaternary ammonium halides, 2-Cl and 2-Br, worked as excellent catalysts for the copolymerization of cyclohexene oxide (CHO) and CO2 at 120 °C. Turnover frequency (TOF) and turnover number (TON) reached 10 000 h−1 and 55 000, respectively, and poly(cyclohexene carbonate) (PCHC) with molecular weight of up to 281 000 was obtained with a catalyst loading of 0.001 mol%. In contrast, bifunctional MgII and ZnII counterparts, 3-Cl and 4-Cl, as well as a binary catalyst system, 1-Cl with bis(triphenylphosphine)iminium chloride (PPNCl), showed poor catalytic performances. Kinetic studies revealed that the reaction rate was first-order in [CHO] and [2-Br] and zero-order in [CO2], and the activation parameters were determined: ΔH‡ = 12.4 kcal mol−1, ΔS‡ = −26.1 cal mol−1 K−1, and ΔG‡ = 21.6 kcal mol−1 at 80 °C. Comparative DFT calculations on two model catalysts, AlIII complex 2′ and MgII complex 3′, allowed us to extract key factors in the catalytic behavior of the bifunctional AlIII catalyst. The high polymerization activity and carbonate-linkage selectivity originate from the cooperative actions of the metal center and the quaternary ammonium cation, both of which facilitate the epoxide-ring opening by the carbonate anion to form the carbonate linkage in the key transition state such as TS3b (ΔH‡ = 13.3 kcal mol−1, ΔS‡ = −3.1 cal mol−1 K−1, and ΔG‡ = 14.4 kcal mol−1 at 80 °C)

A Potassium Diboryllithate: Synthesis, Bonding Properties, and the Deprotonation of Benzene

A potassium diboryllithate (B2LiK) was synthesized and structurally characterized. DFT calculations, including NPA and AIM analyses of B2LiK, revealed ionic interactions between the two bridging boryl anions and Li+ and K+. Upon standing in benzene, B2LiK deprotonated the solvent to form a hydroborane and a phenylborane. On the basis of DFT calculations, a detailed reaction mechanism, involving deprotonation and hydride/phenyl exchange processes, is proposed. An NBO analysis of the transition state for the deprotonation of benzene suggests that the deprotonation should be induced by the coordination of benzene to the K+.A â LiK â of work: A potassium diboryllithate, B2LiK, was synthesized and structurally characterized. The bonding situation in this compound was examined by NMR, XRD, NPA, and AIM analyses. B2LiK is able to deprotonate benzene with concomitant formation of phenylborane as the major product. A detailed reaction mechanism based on DFT calculations suggests that the deprotonation of benzene should be initiated by a transition state involving the coordination of benzene to K+.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137264/1/anie201605005_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137264/2/anie201605005-sup-0001-misc_information.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137264/3/anie201605005.pd

Gravitational fermion creation during an anisotropic phase of cosmological expansion

The free Dirac equation is solved in a Bianchi Type I space-time, which represents a homogeneous but anisotropic universe, to show the creation of fermionic particles. It is found that unlike in the isotropic case, massless fermion production is possible. An estimate of the energy density of massless particles created during an early anisotropic phase of cosmological expansion is shown to cause substantial back-reaction on the gravitational field. The potential relevance to dark matter particle production, primordial magnetogenesis, and early universe cosmology is discussed briefly.Comment: Accepted for publication in Physical Review

Human iPSC-derived renal collecting duct organoid model cystogenesis in ADPKD

腎集合管オルガノイドを用いた多発性嚢胞腎モデルの作製 iPS創薬により治療薬候補を発見、治験開始へ. 京都大学プレスリリース. 2023-12-01.Developing more advanced renal organoids to model polycystic kidney disease. 京都大学プレスリリース. 2023-12-01.In autosomal dominant polycystic kidney disease (ADPKD), renal cyst lesions predominantly arise from collecting ducts (CDs). However, relevant CD cyst models using human cells are lacking. Although previous reports have generated in vitro renal tubule cyst models from human induced pluripotent stem cells (hiPSCs), therapeutic drug candidates for ADPKD have not been identified. Here, by establishing expansion cultures of hiPSC-derived ureteric bud tip cells, an embryonic precursor that gives rise to CDs, we succeed in advancing the developmental stage of CD organoids and show that all CD organoids derived from PKD1−/− hiPSCs spontaneously develop multiple cysts, clarifying the initiation mechanisms of cystogenesis. Moreover, we identify retinoic acid receptor (RAR) agonists as candidate drugs that suppress in vitro cystogenesis and confirm the therapeutic effects on an ADPKD mouse model in vivo. Therefore, our in vitro CD cyst model contributes to understanding disease mechanisms and drug discovery for ADPKD

Association between PPARGC1A polymorphisms and the occurrence of nonalcoholic fatty liver disease (NAFLD)

<p>Abstract</p> <p>Background</p> <p>Genetic factors as well as environmental factors are important in the development of NAFLD and in this study we investigated associations between polymorphisms of peroxisome proliferators-activated receptor γ coactivator 1α polymorphism (<it>PPARGC1A</it>) and NAFLD.</p> <p>Aims</p> <p>We recruited 115 patients with biopsy-proven NAFLD, 65 with NASH and 50 with simple steatosis, and 441 healthy control subjects and investigated 15 SNPs of <it>PPARGC1A</it>.</p> <p>Results</p> <p>SNP rs2290602 had the lowest <it>p </it>value in the dominant mode (<it>p </it>= 0.00095), and the odds ratio for NAFLD (95% CI) was 2.73 (1.48 – 5.06). rs2290602 was significantly associated with NAFLD even when the most conservative Bonferroni's correction was applied (<it>p </it>= 0.0143). The frequency of the T allele of rs2290602 was significantly higher in the NASH patients than in the control subjects (<it>p </it>= 0.00093, allele frequency mode), and its frequency in the NASH patients tended to be higher than in the simple steatosis patients (<it>p </it>= 0.09). The results of the real-time RT-PCR study showed that intrahepatic mRNA expression of <it>PPARGC1A </it>was lower in the TT group than in the GG or GT group at SNP rs2290602 (p = 0.0454).</p> <p>Conclusion</p> <p>This is the first study to demonstrate a significant association between genetic variations in <it>PPARGC1A </it>and NAFLD. This finding suggested that <it>PPARGC1A </it>polymorphism and lower expression of <it>PPARGC1A </it>mRNA in the liver are an important genetic contribution to etiology of NAFLD.</p

Various Problems Concerning the Construction of a WWW Japanese-Language Corpus― The Current State and Future Prospects of Japanese-Language Corpus Research ―

The objective of this paper is to discuss various problems that arise when Japanese-language text that is circulating on the World-Wide Web （WWW）is utilized as a corpus. First of all, our review of previous research relating to Japanese-language corpora showed that research into the application of the WWW as a Japanese-language corpus has still not been tackled sufficiently. We then studied all of the research papers that were presented at national conventions over a two-year period for one Japanese academic society relating to information and education. As a result, it became clear that although there have been several research projects into the use of text-mining methods, there has been almost no research relating to WWW Japanese-language corpora. In the light of these findings, we considered the various problems that might arise during research into WWW Japanese-language corpora. In other words, some of the points that we need to consider include: 1） sample bias, 2）the self-images projected by authors, 3）proof of the validity of such contents, 4）the large numbers of submissions by the same people, 5）the fact that data management including the revision and update of such contents is often done at the individual level, and 6）plagiarism of written works and quoting from other sites. Thus, although sample bias does remain, we can say that the Internet gives us the first opportunity in history to accumulate vast quantities of personally-published data. We have become able to utilize the Internet both quantitatively and qualitatively as a modern intellectual resource. Once we have clarified suitable methods for using this intellectual resource as a target of research in analysis, we should be able to engage in research towards structuring a WWW Japanese-language corpus in the future