Synthesis and Chiroptical Properties of Binaphthyl-Hinged [5]Helicenes

The synthesis, structure, and circularly polarized luminescence (CPL) of two types of shape-persistent [5]helicenes, hinged by a tethered (−OCH₂CH₂O−) or untethered (−OCH₃) binaphthyl, are reported. The binaphthyl tethering system facilitated an effective Wittig ring-closure reaction in the synthesis of a macrocyclic precursor, which could be easily converted to the title compound via successive photocyclization. The tethered groups were replaced with untethered −OCH₃ groups by treatment with BBr₃ followed by methylation. Both compounds exhibited similar spectra, and their longest wavelength absorption band with a low intensity was attributed to the transition from HOMO to LUMO+1. These compounds exhibited CPL with higher dissymmetry factors g_lum values than unlocked helicenes.     

Effect of ultrasound assisted konjac glucomannan treatment on properties of chicken plasma protein gelation

The effect of ultrasound assisted konjac glucomannan treatment on the properties of chicken plasma protein gelation was investigated in this study. There were four gelation groups as follows: untreated plasma protein gelation (Control), gelation added konjac glucomannan (KGG), gelation by ultrasound treatment alone (UG) and gelation added konjac glucomannan combined with ultrasound treatment (KGUG). The data showed that the gelation strength and water-holding capacity of the treated groups were significantly increased compared with those of Control. The strongest bonding water was present in KGUG, followed by KGG and UG in low-field nuclear magnetic resonance. The storage energy (G′) and loss energy modulus (G″) of KGUG showed the largest rheological properties, and the G′ value was higher than that of G″. Furthermore, the elastic and gelatinous properties of UG, KGG and KGUG played a dominant role in viscoelasticity. After konjac glucomannan addition, the particle size of KGG increased significantly. Compared with that of the Control and KGG, the average particle size of UG and KGUG decreased significantly after ultrasound treatment. The hydrophobicity and disulfide bonds mainly affected the formation of heat-induced gelation in these four groups. Furthermore, KGUG with the highest hydrophobicity and disulfide bonds revealed the best stability. Therefore, the gelation of chicken plasma protein by ultrasound assisted konjac glucomannan treatment had excellent gelling properties.     

Property ∏σ and tensor products of operator algebras

In this paper, we introduce Property ∏σ of operator algebras and prove that nest subalgebras and the finite-width CSL subalgebras of arbitrary von Neumann algebras have Property ∏σ.Finally, we show that the tensor product formula alg ML1-(×)algNL2 = algM-(×)N(L1 (×) L2) holds for any two finite-width CSLs L1 and L2 in arbitrary von Neumann algebras M and N, respectively.     

Level algebras with bad properties

This paper can be seen as a continuation of the works contained in the recent article (J. Alg., 305 (2006), 949-956) of the second author, and those of Juan Migliore (math. AC/0508067). Our results are:

1). There exist codimension three artinian level algebras of type two which do not enjoy the Weak Lefschetz Property (WLP). In fact, for , we will construct a codimension three, type two -vector of socle degree such that all the level algebras with that -vector do not have the WLP. We will also describe the family of those algebras and compute its dimension, for each .

2). There exist reduced level sets of points in of type two whose artinian reductions all fail to have the WLP. Indeed, the examples constructed here have the same -vectors we mentioned in 1).

3). For any integer , there exist non-unimodal monomial artinian level algebras of codimension . As an immediate consequence of this result, we obtain another proof of the fact (first shown by Migliore in the above-mentioned preprint, Theorem 4.3) that, for any , there exist reduced level sets of points in whose artinian reductions are non-unimodal.

     

Highly-sensitive electrochemical sensing platforms for food colourants based on the property-tuning of porous carbon

It is very challenging to develop highly-sensitive analytical platforms for toxic synthetic colourants that widely added in food samples. Herein, a series of porous carbon (PC) was prepared using CaCO₃ nanoparticles (nano-CaCO₃) as the hard template and starch as the carbon precursor. Characterizations of scanning electron microscopy and transmission electron microscopy indicated that the morphology and porous structure were controlled by the weight ratio of starch and nano-CaCO₃. The electrochemical behaviours of four kinds of widely-used food colourants, Sunset yellow, Tartrazine, Ponceau 4R and Allura red, were studied. On the surface of PC samples, the oxidation signals of colourants enhanced obviously, and more importantly, the signal enhancement abilities of PC were also dependent on the starch/nano-CaCO₃ weight ratio. The greatly-increased electron transfer ability and accumulation efficiency were the main reason for the enhanced signals of colourants, as confirmed by electrochemical impedance spectroscopy and chronocoulometry. The prepared PC-2 sample by 1:1 starch/nano-CaCO₃ weight ratio was more active for the oxidation of food colourtants, and increased the signals by 89.4-fold, 79.3-fold, 47.3-fold and 50.7-fold for Sunset yellow, Tartrazine, Ponceau 4R and Allura red. As a result, a highly-sensitive electrochemical sensing platform was developed, and the detection limits were 1.4, 3.5, 2.1 and 1.7 μg L⁻¹ for Sunset yellow, Tartrazine, Ponceau 4R and Allura red. The practical application of this new sensing platform was demonstrated using drink samples, and the detected results consisted with the values that obtained by high-performance liquid chromatography.     

金纳米棒基智能复合纳米水凝胶的研究进展

金纳米棒(AuNRs)基智能复合纳米水凝胶是一类结合了AuNRs和智能纳米水凝胶两者独特性能的智能纳米材料,其最大特点是可通过外界刺激来调节AuNRs的多种性能,或通过测定其性能变化来感知外界刺激。本文首先介绍了目前文献报道的核壳结构型、无规充填型、草莓型三种形态结构的AuNRs基智能复合纳米水凝胶的特点及其合成方法。然后,总结了金纳米棒基智能复合纳米水凝胶的性能与应用研究进展。最后,对其未来的研究方向和发展前景作出了展望。     

α-Fe2O3磁性微球的合成及磁性能

以氯化铁（FeCl3·6H2O）和氨水（NH3·H2O）为原料,以十六烷基三甲基溴化铵（CTAB）为表面活性剂,采用沉淀法制备了氧化铁磁性微球.所得样品用XRD、SEM及SQUID-VSM等手段进行了表征.结果表明,所得氧化铁磁性微球为斜方六面体结构,其粒径大小在0.5-1.5μm范围,其剩余磁感应强度为0.06emu/g,矫顽力为1700Oe,表现出一定的铁磁性.     

On local spectral properties of complex symmetric operators

In this paper we study properties of complex symmetric operators. In particular, we prove that every complex symmetric operator having property (β) or (δ) is decomposable. Moreover, we show that complex symmetric operator T has Dunford?s property (C) and it satisfies Weyl?s theorem if and only if its adjoint does.     

汉麻-一种高值特种生物质资源及应用

汉麻作为一种特种生物资源,其开发涉及到众多产业,它的产业化将对国民经济建设产生深远的影响。本文在研究汉麻种植及纤维结构与性能的基础上,在汉麻纤维精细化加工、汉麻秆的产业应用、汉麻籽的综合利用等方面进行了深入的研究,为汉麻全面综合利用打下了坚实的基础。依托综合利用技术的研究成果,正在国内建立世界上第一个汉麻产业化基地,将...     

约化Banach 代数的谱不变性和双曲群

主要研究了可数离散群的性质 SRD, 并证明了具有性质 SRD的群上的速降函数全体组成的空间是约化Banach代数 谱不变的稠密子代数. 最后作为例子给出了双曲群具有性质 SRD.