Ultra-directional high-efficient chiral silicon photonic circuits

Chiral light matter interaction enables new fundamental researches and applications of light. The interaction has traditionally faced challenges in low directionality and efficiency based on spin orbit interaction of light in microscopic waveguides. It is pivotal to exploit photonic integrated circuits to efficiently engineer photonic chiral behavior. Here, we present ultra directional high efficient chiral coupling in silicon photonic circuits based on low order to high order mode conversion and interference. We show that the directionality of chiral coupling, in principle, can approach minus/plus 1 with circular polarization inputs, benefited from the underlying mechanism of complete destructive and constructive interference. The chiral coupling efficiency can exceed 70%, with negligible scattering to nonguided modes, much higher than conventional coupling mechanisms. Moreover, the chiral silicon photonic circuits can function as a perfect 3 dB power splitter for arbitrarily linear polarization inputs, and also open up the possibility of on chip chirality determination to further flourish the development of chiral optics

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Highly Substituted Cyclopentane–CMP Conjugates as Potent Sialyltransferase Inhibitors

Sialylconjugates on cell surfaces are involved in many biological events such as cellular recognition, signal transduction, and immune response. It has been reported that aberrant sialylation at the nonreducing end of glycoconjugates and overexpression of sialyltransferases (STs) in cells are correlated with the malignance, invasion, and metastasis of tumors. Therefore, inhibitors of STs would provide valuable leads for the discovery of antitumor drugs. On the basis of the transition state of the enzyme-catalyzed sialylation reaction, we proposed that the cyclopentane skeleton in its two puckered conformations might mimic the planar structure of the donor (CMP-Neu5Ac) in the transition state. A series of cyclopentane-containing compounds were designed and synthesized by coupling different cyclopentane α-hydroxyphosphonates with cytidine phosphoramidite. Their inhibitory activities against recombinant human ST6Gal-I were assayed, and a potent inhibitor <b>48</b><i><b>l</b></i> with a <i>K</i>_i of 0.028 ± 0.006 μM was identified. The results show that the cyclopentanoid-type compounds could become a new type of sialyltransferase inhibitors as biological probes or drug leads

2-(1<i>H</i>-2-Benzimidazolyl)-6-(1-(arylimino)ethyl)pyridyl Iron(II) and Cobalt(II) Dichlorides: Syntheses, Characterizations, and Catalytic Behaviors toward Ethylene Reactivity

A series of tridentate N̂N̂N iron(II) and cobalt(II) dichloride complexes bearing 2-(1H-2-benzimidazolyl)-6-(1-(arylimino)ethyl)pyridines were synthesized and characterized by elemental and spectroscopic analyses. Single-crystal X-ray diffraction studies of representative examples of the cobalt and iron complexes confirm distorted bipyramidal geometry around the metal center. Upon coordination of a methanol solvent molecule, a geometry change to distorted octahedral was observed. The steric and electronic effects on catalytic activity are evaluated for different substituents in the arylimino part of the ligand: Me, Et, iPr, Cl, and Br in ortho- and Me and H in para-position. On treatment with methylaluminoxane (MAO) or modified MAO (MMAO), the iron(II) complexes exhibited good activities of up to 106 g·mol−1(Fe)·h−1 for ethylene oligomerization and moderate activities for polymerization, while cobalt(II) complexes showed moderate activities for ethylene dimerization. The best activities were observed with iron complexes with bulky iPr groups in the aryl moiety. In comparison to the analogues containing the 2-(1-alkyl-2-benzimidazolyl)-6-(1-(arylimino)ethyl)pyridines, the iron complexes bearing 2-(1H-2-benzimidazolyl)-6-(1-(arylimino)ethyl)pyridines showed the best activity toward ethylene reactivity

2-(1<i>H</i>-2-Benzimidazolyl)-6-(1-(arylimino)ethyl)pyridyl Iron(II) and Cobalt(II) Dichlorides: Syntheses, Characterizations, and Catalytic Behaviors toward Ethylene Reactivity

A series of tridentate N̂N̂N iron(II) and cobalt(II) dichloride complexes bearing 2-(1H-2-benzimidazolyl)-6-(1-(arylimino)ethyl)pyridines were synthesized and characterized by elemental and spectroscopic analyses. Single-crystal X-ray diffraction studies of representative examples of the cobalt and iron complexes confirm distorted bipyramidal geometry around the metal center. Upon coordination of a methanol solvent molecule, a geometry change to distorted octahedral was observed. The steric and electronic effects on catalytic activity are evaluated for different substituents in the arylimino part of the ligand: Me, Et, iPr, Cl, and Br in ortho- and Me and H in para-position. On treatment with methylaluminoxane (MAO) or modified MAO (MMAO), the iron(II) complexes exhibited good activities of up to 106 g·mol−1(Fe)·h−1 for ethylene oligomerization and moderate activities for polymerization, while cobalt(II) complexes showed moderate activities for ethylene dimerization. The best activities were observed with iron complexes with bulky iPr groups in the aryl moiety. In comparison to the analogues containing the 2-(1-alkyl-2-benzimidazolyl)-6-(1-(arylimino)ethyl)pyridines, the iron complexes bearing 2-(1H-2-benzimidazolyl)-6-(1-(arylimino)ethyl)pyridines showed the best activity toward ethylene reactivity

Reconfigurable integrated full-dimensional optical lattice generator

Optical lattices with periodic potentials have attracted great attention in modern optics and photonics, enabling extensive applications in atomic manipulation, optical trapping, optical communications, imaging, sensing, etc. In the last decade, the generation of optical lattices has been widely investigated by various approaches such as multi-plane-wave interferometer, beam superposition, spatial light modulators, nanophotonic circuits, etc. However, all of the previous state-of-the-art works are restricted to only one or two dimensions of the light field, which cannot fulfill the increasing demand on complex light manipulation. Full-dimensional and dynamic control of the light field, including spatial amplitude, phase and polarization, is quite challenging and indispensable for the generation of sophisticated optical lattices. Here, we propose and demonstrate a reconfigurable integrated full-dimensional optical lattice generator, i.e. a photonic emitting array (PEA) enabling reconfigurable and full-dimensional manipulation of optical lattices, in which 4x4 photonic emitting units (PEUs) with 64 thermo-optic microheaters are densely integrated on a silicon chip. By engineering each PEU precisely with independent and complete control of optical properties of amplitude, phase and polarization, various optical vortex lattices, cylindrical vector beam lattices, and vector vortex beam lattices can be generated and reconfigured in the far field. The demonstrated integrated optical lattice generator paves the way for the miniaturization, full-dimensional control and enhanced flexibility of complex light manipulation

A Potent, Water-Soluble and Photoinducible DNA Cross-Linking Agent

Water-soluble DNA cross-linking phenol and biphenol derivatives 3 and 6 have been synthesized by a Mannich reaction. Both of them can cross-link DNA by photoactivation using visible light (wavelength > 400 nm). Compound 6 can cross-link DNA at pH 5.0 and 7.7, whereas no cross-link was observed at pH 10.0. Density functional theory (DFT) calculation indicated that 6 displays a twist structure. Therefore, it could bind to DNA naturally and has potent property to cross-link DNA after photoactivation

Genetic diversity and trap success of sub-population B from 1984 to 1990.

<p>a)–f) yearly, g)–l) spring and autumn genetic diversity (<i>Na</i>, <i>Ne</i>, <i>I</i>, <i>He,</i> and <i>Ho</i>) and trap success (T%) of sub-population B from 1984 to 1990. <i>Na</i>, <i>Ne</i>, <i>I</i>, <i>He</i>, and <i>Ho</i>: see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0054171#pone-0054171-g002" target="_blank">figure 2</a>.</p

Variation of Genetic Diversity in a Rapidly Expanding Population of the Greater Long-Tailed Hamster (<em>Tscherskia triton</em>) as Revealed by Microsatellites

<div><p>Genetic diversity is essential for persistence of animal populations over both the short- and long-term. Previous studies suggest that genetic diversity may decrease with population decline due to genetic drift or inbreeding of small populations. For oscillating populations, there are some studies on the relationship between population density and genetic diversity, but these studies were based on short-term observation or in low-density phases. Evidence from rapidly expanding populations is lacking. In this study, genetic diversity of a rapidly expanding population of the Greater long-tailed hamsters during 1984–1990, in the Raoyang County of the North China Plain was studied using DNA microsatellite markers. Results show that genetic diversity was positively correlated with population density (as measured by % trap success), and the increase in population density was correlated with a decrease of genetic differentiation between the sub-population A and B. The genetic diversity tended to be higher in spring than in autumn. Variation in population density and genetic diversity are consistent between sub-population A and B. Such results suggest that dispersal is density- and season-dependent in a rapidly expanding population of the Greater long-tailed hamster. For typically solitary species, increasing population density can increase intra-specific attack, which is a driving force for dispersal. This situation is counterbalanced by decreasing population density caused by genetic drift or inbreeding as the result of small population size. Season is a major factor influencing population density and genetic diversity. Meanwhile, roads, used to be considered as geographical isolation, have less effect on genetic differentiation in a rapidly expanding population. Evidences suggest that gene flow (Nm) is positively correlated with population density, and it is significant higher in spring than that in autumn.</p> </div

Genetic diversity and trap success of the whole population from 1984 to 1990.

<p>a)–f) yearly, g)–l) spring and autumn genetic diversity (<i>Na</i>, <i>Ne</i>, <i>I</i>, <i>He</i>, and <i>Ho</i>) and trap success (T%) of the whole population from 1984 to 1990. <i>Na</i>, <i>Ne</i>, <i>I</i>, <i>He</i>, and <i>Ho</i>: see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0054171#pone-0054171-g002" target="_blank">figure 2</a>.</p