There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

J. Appl. Cryst.の発刊に際して

A fundamental aim in the field of catalysis is the development of new modes of small molecule activation. One approach toward the catalytic activation of organic molecules that has received much attention recently is visible light photoredox catalysis. In a general sense, this approach relies on the ability of metal complexes and organic dyes to engage in single-electron-transfer (SET) processes with organic substrates upon photoexcitation with visible light.

Many of the most commonly employed visible light photocatalysts are polypyridyl complexes of ruthenium and iridium, and are typified by the complex tris(2,2′-bipyridine) ruthenium(II), or Ru(bpy)32+ (Figure 1). These complexes absorb light in the visible region of the electromagnetic spectrum to give stable, long-lived photoexcited states.1,2 The lifetime of the excited species is sufficiently long (1100 ns for Ru(bpy)32+) that it may engage in bimolecular electron-transfer reactions in competition with deactivation pathways.3 Although these species are poor single-electron oxidants and reductants in the ground state, excitation of an electron affords excited states that are very potent single-electron-transfer reagents. Importantly, the conversion of these bench stable, benign catalysts to redox-active species upon irradiation with simple household lightbulbs represents a remarkably chemoselective trigger to induce unique and valuable catalytic processes.






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Figure 1


Ruthenium polypyridyl complexes: versatile visible light photocatalysts.

/pdf/visible-light-photoredox-catalysis-with-transition-metal-5d1oxrsczo.pdf

Visible Light Photoredox Catalysis with Transition Metal Complexes: Applications in Organic Synthesis

Two new Cα-tetrasubstituted α-amino acids (2R,3S)-((1R,2S,5R)-2-isopropyl-5-methylcyclohexyl) 2-(4-bromophenyl)-3-(tert-butoxycarbonylamino)-tetrahydrofuran-3-carboxylate and (2S,3R)-((1R,2S,5R)-2-isopropyl-5-methylcyclohexyl) 2-(4-bromophenyl)-3-(tert-butoxycarbonylamino)-tetrahydrofuran-3-carboxylate were synthesized and characterized by NMR, MS, elemental analysis and X-ray.

https://www.mdpi.com/1422-8599/2009/1/M594/pdf

Synthesis of (2R,3S)-((1R,2S,5R)-2-isopropyl-5-methylcyclohexyl) 2-(4-bromophenyl)-3-(tert-butoxy-carbonylamino)-tetrahydrofuran-3-carboxylate and (2S,3R)-((1R,2S,5R)-2-isopropyl- 5-methylcyclohexyl)2-(4- bromophenyl)-3-(tert-butoxycarbonylamino)-tetrahydrofuran-3-carboxylate

The hydrogen-bond-guided self-assembly of 5'-ribonucleotides bearing adenine(A), cytosine (C), uracil (U), or guanine (G) bases from aqueous solution on a lipid-like surface decorated with synthetic bis(Zn(II)-cyclen) (cyclen=1,4,7,10-tetraazacyclodododecane) metal-complex receptor sites is described. The process was studied by using surface plasmon resonance spectroscopy. The data show that the mechanism of nucleotide binding to the 2D template is influenced by the chemistry of the bases and the pH value of the solution. In a neutral solution of pH 7.5, the process is cooperative and selective with respect to Watson-Crick pairs (A-U and C-G), which form stable double planes in accordance with the Chargaff rule. In a more acidic solution at pH 6.0, the interactions between complementary partners become non-cooperative and the surface also stabilizes mismatched and wobble pairs due to the pH-induced changes in the receptor coordination state. The results suggest that hydrogen bonding plays a key role in the self-assembly of complementary nucleotides at the lipid-like interface, and the cooperative character of the process stems from the ideal matching of the orientation and chemistry of all the interacting components with respect to each other in neutral solution.

Hydrogen‐Bond‐Guided Self‐Assembly of Nucleotides on a Receptor‐Array Surface

Co-embedding of an amphiphilic non-chiral hydrolysis catalyst with amphiphilic chiral additives into the membrane of a phospholipid vesicle induces different rates of ester hydrolysis for enantiomeric amino acid esters.

/pdf/enantioselective-ester-hydrolysis-by-an-achiral-catalyst-co-23qqa59z58.pdf

Enantioselective ester hydrolysis by an achiral catalyst co-embedded with chiral amphiphiles into a vesicle membrane

4 Flavin photocatalysis

We report here a new synthetic route to highly-substituted tetraazamacrocycles. Raney nickel hydrogenation of macrocyclic phenylenediamine–acetylacetone condensation products gives cyclams in high yield with complexes all-cis stereoselectivity. The extensive C-substitution of the cyclam 2a changes its ligand properties markedly. The X-ray structure analyses of NiII, CuII, and ZnII complexes of 2a reveals a deviation of the metal ion coordination geometry from the usual square-planar arrangement. This may account for the differences in the redox properties of the NiII and CuII complexes of 2a leads to more positive oxidation and reduction potentials compared to the analogous unsubstituted cyclam complexes. While the binding constant between Zn(ClO4)2 and 2a is lower by a factor of 105 compared to cyclam, the subsequent binding of uridine to the zinc-cyclam complexes in methanol/water is slightly stronger in the case of 2a · Zn(ClO4)2].

Burkhard König

Papers

Synthesis of (2R,3S)-((1R,2S,5R)-2-isopropyl-5-methylcyclohexyl) 2-(4-bromophenyl)-3-(tert-butoxy-carbonylamino)-tetrahydrofuran-3-carboxylate and (2S,3R)-((1R,2S,5R)-2-isopropyl- 5-methylcyclohexyl)2-(4- bromophenyl)-3-(tert-butoxycarbonylamino)-tetrahydrofuran-3-carboxylate

Hydrogen‐Bond‐Guided Self‐Assembly of Nucleotides on a Receptor‐Array Surface

Enantioselective ester hydrolysis by an achiral catalyst co-embedded with chiral amphiphiles into a vesicle membrane

4 Flavin photocatalysis

Highly Substituted Cyclams: Stereoselective Synthesis and Coordination Properties