Selection of Planar Chiral Conformations between Pillar[5,6]arenes Induced by Amino Acid Derivatives in Aqueous Media

Chiral α-amino acids play critical roles in the metabolic process in nearly all life forms. So far, chiral recognition of α-amino acids has mainly focused on the determination of l /d enantiomers. Herein, selection of planar chiral conformations between water-soluble pillar[5]arene WP5 and pillar[6]arene WP6 was observed due to α-side chain or ethyl ester moieties of l -α-amino acid ethyl ester hydrochlorides binding with WP5 and WP6 , respectively. Therefore, α-side chain and ethyl ester moieties of l -α-amino acid ethyl ester hydrochlorides were recognized by observing the induced CD signal and its inversion. This is a rare example of being able to detect the chiral region around α-carbon of a chiral α-amino acid molecule.     

Multilevel Chirality Transfer from Amino Acid Derivatives to Circularly Polarized Luminescence-Active Nanoparticles in Aqueous Medium

Chirality at different levels is widely observed in nature, but the clue to connect it all together, and the way chirality transfers among different levels are still obscure. Herein, a l -/d -lysine-based self-assembly system was constructed, in which two-step chirality transfer among three different levels was observed in aqueous solution. The chirality originated from the point chirality of amino acid derivatives l -/d -PyLys hydrochloride, and was transferred to the planar conformational chirality of water-soluble pillar[5]arene pR-/pS-WP5. Then, with the aid of pR-/pS-WP5, nanoparticles were formed that exhibited L-/R-handed circularly polarized luminescence with a dissymmetry factor of up to ±0.001, arising from pyrene chiral excimers. This multilevel chirality transfer not only provides a perspective to trace potential clues, and to pursue certain ways by which the chirality transfers, but also offers a strategy to create controllable CPL emission in aqueous media.     

A gram-scale laboratory synthesis of Annonaceous acetogenin mimic AA005

AA005(1),a potent anticancer mimicking molecule of natural Annonaceous acetogenin,features a central C₂-symmetric triglycol moiety and three stereogenic centers.To support ongoing animal studies,a scalable 10-step synthesis of AA005(1) has been studied,optimized and accomplished in this work,starting from commercially available economic materials ethylene glycol and(R)-epichlorohydrin.A regio-and stereo-controlled BF₃·Et₂O-promoted epoxide opening of(R)-epichlorohydrin with ethylene glycol was investigated,optimized and successfully applied to the scalable preparation of the crucial fragment 6 a with C₂-symmetry.Further successive epoxide openings elaborated both two side chains and the whole skeleton with proper nucleophiles and electrophiles.Comparison and optimization of the reaction sequences finally led to completion of a new multi-gram synthesis ofAA005(1) with satisfactory enantiomeric and diastereomeric purity.     

二氧化钛纳米棒的制备及抗菌性能研究

通过一种简单的水热法制备了TiO2纳米棒。采用微量稀释法研究TiO2纳米棒对绿脓杆菌的抗菌性能,细菌菌落计数基于光密度测试在96孔细胞培养板上生长的细菌给出。抗菌结果表明,TiO2纳米棒对革兰氏阴性菌（绿脓杆菌）表现出明显的抗菌效率。TiO2纳米棒对绿脓杆菌的抗菌效率达到95.2%。结论：TiO2纳米棒具有优异的抗菌性能。     

Structural and magnetic properties of single-crystalline Co-doped barium titanate nanoparticles

Undoped and Co-doped BaTiO₃ nanoparticles were synthesized by a one-step sol-precipitation method. For all the samples, X-ray diffraction showed characteristic diffraction lines for BaTiO₃ without the indication of secondary phases. High-resolution transition electron microscopy images showed that BaTiO₃ nanoparticles exhibit the nature of single-crystal. Magnetometry revealed that all the Co-doped BaTiO₃ samples show paramagnetic behaviors and Co ions in BaTiO₃ are present as isolated paramagnetic centers. This is contrasted to several reported cases of ferromagnetism in Co-doped BaTiO₃.     

Hybrids of LiMn2O4 nanoparticles anchored on carbon nanotubes/graphene sheets as long-cycle-life cathode material for rechargeable hybrid aqueous batteries

Journal of Solid State Electrochemistry - A hybrid LiMn2O4-graphene-carbon nanotubes (LMO-GN-CNT) material is synthesized successfully by a facile hydrothermal method. The 15-nm-nanosized LiMn2O4...     

Biological experimental demonstration of bifurcations from bursting to spiking predicted by theoretical models

A series of bifurcations from period-1 bursting to period-1 spiking in a complex (or simple) process were observed with increasing extra-cellular potassium concentration during biological experiments on different neural pacemakers. This complex process is composed of three parts: period-adding sequences of burstings, chaotic bursting to chaotic spiking, and an inverse period-doubling bifurcation of spiking patterns. Six cases of bifurcations with complex processes distinguished by period-adding sequences with stochastic or chaotic burstings that can reach different bursting patterns, and three cases of bifurcations with simple processes, without the transition from chaotic bursting to chaotic spiking, were identified. It reveals the structures closely matching those simulated in a two-dimensional parameter space of the Hindmarsh–Rose model, by increasing one parameter \(I\) and fixing another parameter \(r\) at different values. The experimental bifurcations also resembled those simulated in a physiologically based model, the Chay model. The experimental observations not only reveal the nonlinear dynamics of the firing patterns of neural pacemakers but also provide experimental evidence of the existence of bifurcations from bursting to spiking simulated in the theoretical models.