Iron- and bismuth-catalyzed asymmetric Mukaiyama aldol reactions in aqueous media

We have developed asymmetric Mukaiyama aldol reactions of silicon enolates with aldehydes catalyzed by chiral Fe II and Bi III complexes. Although previous reactions often required relatively harsh conditions, such as strictly anhydrous conditions, very low temperatures (-78 C), etc., the reactions reported herein proceeded in the presence of water at 0 C. To find appropriate chiral water-compatible Lewis acids for the Mukaiyama aldol reaction, many Lewis acids were screened in combination with chiral bipyridine L1, which had previously been found to be a suitable chiral ligand in aqueous media. Three types of chiral catalysts that consisted of a Fe II or Bi III metal salt, a chiral ligand (L1), and an additive have been discovered and a wide variety of substrates (silicon enolates and aldehydes) reacted to afford the desired aldol products in high yields with high diastereo- and enantioselectivities through an appro- priate selection of one of the three catalytic systems. Mechanistic studies elucidated the coordination environments around the Fe II and Bi III centers and the effect of additives on the chiral catalysis. Notably, both Brønsted acids and bases worked as efficient additives in the Fe II-catalyzed reactions. The assumed catalytic cycle and transition states indicated important roles of water in these efficient asymmetric Mukaiyama aldol reactions in aqueous media with the broadly applicable and versatile catalytic systems

Product gas analysis of laminar premixed ammonia-methane flames in stagnation flows

Ammonia is a promising hydrogen energy vector and a carbon-free fuel; hence the use of ammonia-hydrocarbon fuel blends can be viewed as an intermediate step towards a hydrogen economy. The characterization of methane-ammonia emissions is essential for designing combustors for a broader range of fuels while fulfilling strict NOx emission requirements and global warming targets. The product gas trends of laminar premixed ammonia-methane flames at atmospheric pressure were studied for 0.1 to 0.6 ammonia heat ratios at the operable range of equivalence ratios. Gases including NO, N2O, NO2, HCN, CO and NH3 were measured using the dual dilution gas method and compared against numerical predictions. Experimental results showed the highest NO emissions at approximately 8,000 ppm for the 0.3 and 0.4 ammonia heat ratios, reducing twofold at the extreme heat ratio conditions. The optimal condition for reducing NOx emissions while maintaining low unburnt NH3 was found to occur at a 1.20 equivalence ratio for higher ammonia ratios, moving incrementally closer towards 1.35 as the methane ratio was increased. These results can aid a further reaction model analysis due to the availability of stain stabilised stagnation flame models in numerical software

Long-term effectiveness of right septal pacing vs. right apical pacing in patients with atrioventricular block

AbstractBackgroundLong-term right ventricular apical (RVA) pacing increases the risk of heart failure (HF) by inducing ventricular dyssynchronization. Although recent studies suggest that right ventricular septal (RVS) pacing results in improved short-term outcomes, its long-term effectiveness remains unclear.Methods and resultsThis study investigated 149 consecutive patients who underwent implantation of a dual chamber pacemaker for atrioventricular block with either RVS-pacing between July 2007 and June 2010 or RVA-pacing between January 2003 and June 2007. The endpoint was defined as death and hospitalization due to heart failure (HF). The rates of mortality and hospitalization due to HF were significantly lower in the RVS-pacing group than that in the RVA-pacing group (event free RVS: 1 year, 98% and 2 years, 98%; RVA: 1 year, 85% and 2 years, 81%; p<0.05). None of the patients died from HF in the RVS-pacing group, while 4 patients died from HF in the RVA-pacing group within 2 years after pacemaker implantation. The paced QRS interval was significantly shorter with RVS pacing than with RVA pacing at different times after pacemaker implantation (RVS: immediately 157.8±24.0ms, after 3 months 157.3±17.5ms, after 6 months 153.6±21.7ms, after 12 months 153.6±19.4ms, after 24 months 149.3±24.0ms vs. RVA: immediately 168.3±23.7ms, after 3 months 168.7±26.0ms, after 6 months 168.0±22.8ms, after 12 months 171.2±22.3ms, after 24 months 176.1±25.5ms; p<0.05).ConclusionsRVS pacing is feasible and safe with more favorable clinical benefits than RVA pacing

Comparative genomic analysis of 1047 completely sequenced cDNAs from an Arabidopsis-related model halophyte, Thellungiella halophila

<p>Abstract</p> <p>Background</p> <p><it>Thellungiella halophila </it>(also known as <it>T. salsuginea</it>) is a model halophyte with a small size, short life cycle, and small genome. <it>Thellungiella </it>genes exhibit a high degree of sequence identity with Arabidopsis genes (90% at the cDNA level). We previously generated a full-length enriched cDNA library of <it>T. halophila </it>from various tissues and from whole plants treated with salinity, chilling, freezing stress, or ABA. We determined the DNA sequences of 20 000 cDNAs at both the 5'- and 3' ends, and identified 9569 distinct genes.</p> <p>Results</p> <p>Here, we completely sequenced 1047 <it>Thellungiella </it>full-length cDNAs representing abiotic-stress-related genes, transcription factor genes, and protein phosphatase 2C genes. The predicted coding sequences, 5'-UTRs, and 3'-UTRs were compared with those of orthologous genes from Arabidopsis for length, sequence similarity, and structure. The 5'-UTR sequences of <it>Thellungiella </it>and Arabidopsis orthologs shared a significant level of similarity, although the motifs were rearranged. While examining the stress-related <it>Thellungiella </it>coding sequences, we found a short splicing variant of <it>T. halophila </it><it>salt overly sensitive 1 </it>(<it>ThSOS1</it>), designated <it>ThSOS1S</it>. ThSOS1S contains the transmembrane domain of ThSOS1 but lacks the C-terminal hydrophilic region. The expression level of <it>ThSOS1S </it>under normal growth conditions was higher than that of <it>ThSOS1</it>. We also compared the expression levels of Na⁺-transport-system genes between <it>Thellungiella </it>and Arabidopsis by using full-length cDNAs from each species as probes. Several genes that play essential roles in Na⁺excretion, compartmentation, and diffusion (<it>SOS1</it>, <it>SOS2</it>, <it>NHX1</it>, and <it>HKT1</it>) were expressed at higher levels in <it>Thellungiella </it>than in Arabidopsis.</p> <p>Conclusions</p> <p>The full-length cDNA sequences obtained in this study will be essential for the ongoing annotation of the <it>Thellungiella </it>genome, especially for further improvement of gene prediction. Moreover, they will enable us to find splicing variants such as <it>ThSOS1S </it>(AB562331).</p

Molecular Transformation of 2-Methylazulenes: An Efficient and Practical Synthesis of 2-Formyl- and 2-Ethynylazulenes

First published: 09 Jan 20182-Formylazulene derivatives have been obtained in good yields by the reactions of 2-methylazulenes with N,N-dimethylformamide dimethyl acetal, followed by oxidative cleavage of the intermediately formed enamines with NaIO4. Vilsmeier formylation of 1-phenyl-3-methylazulenes also afforded the corresponding 2-formylazulenes in moderate yields. The treatment of a 2-methylazulene derivative bearing a formyl group at the 1-position with sodium methoxide led, through a self-condensation reaction, to a trans-1-(azulen-1-yl)-2-(azulen-2-yl)ethylene derivative, the structure of which was verified by single-crystal X-ray diffraction analysis. The 2-formylazulenes obtained were transformed into 2-ethynylazulenes in good yields by a modified Seyferth-Gilbert reaction. The reactivity of a 1-iodoazulene bearing a 2-formyl function in palladium-catalyzed cross-coupling reactions has also been examined.ArticleEUROPEAN JOURNAL OF ORGANIC CHEMISTRY. 2018(9):1145-1157 (2018)journal articl

Engineering a novel multifunctional green fluorescent protein tag for a wide variety of protein research.

BACKGROUND: Genetically encoded tag is a powerful tool for protein research. Various kinds of tags have been developed: fluorescent proteins for live-cell imaging, affinity tags for protein isolation, and epitope tags for immunological detections. One of the major problems concerning the protein tagging is that many constructs with different tags have to be made for different applications, which is time- and resource-consuming. METHODOLOGY/PRINCIPAL FINDINGS: Here we report a novel multifunctional green fluorescent protein (mfGFP) tag which was engineered by inserting multiple peptide tags, i.e., octa-histidine (8xHis), streptavidin-binding peptide (SBP), and c-Myc tag, in tandem into a loop of GFP. When fused to various proteins, mfGFP monitored their localization in living cells. Streptavidin agarose column chromatography with the SBP tag successfully isolated the protein complexes in a native form with a high purity. Tandem affinity purification (TAP) with 8xHis and SBP tags in mfGFP further purified the protein complexes. mfGFP was clearly detected by c-Myc-specific antibody both in immunofluorescence and immuno-electron microscopy (EM). These findings indicate that mfGFP works well as a multifunctional tag in mammalian cells. The tag insertion was also successful in other fluorescent protein, mCherry. CONCLUSIONS AND SIGNIFICANCE: The multifunctional fluorescent protein tag is a useful tool for a wide variety of protein research, and may have the advantage over other multiple tag systems in its higher expandability and compatibility with existing and future tag technologies