Stability improvement of 40Ca+ optical clock by using a transportable ultra-stable cavity.

The instability of the clock laser is one of the primary factors limiting the instability of the optical clocks. We present an ultra-stable clock laser based on a 30-cm-long transportable cavity with an instability of ∼3 × 10-16 at 1 s-100 s. The cavity is fixed by invar poles in three orthogonal directions to restrict the displacement, meeting the requirements of transportability and low vibration sensitivity. By applying the ultra-stable laser to a transportable 40Ca+ optical clock with a systematic uncertainty of 4.8 × 10-18 and using the real-time feedback algorithm to compensate the linear shift of the clock laser, the short-term stability of the transportable 40Ca+ optical clock has been greatly improved from 4.0×10-15/τ/s to 1.16×10-15/τ/s, measured at ∼100 s-1000 s of averaging time, enriching its applications in metrology, optical frequency comparison, and time keeping.

Manipulation of Hierarchical Chiral Self-assembly and Anion Recognition by Supramolecular Systems of ß-Glucopyranoside, Pillar[5]arenes, and Polyoxometalates.

Hierarchical chiral structures have broad applications in optical devices, asymmetric catalysis, and biological systems. The delicate balance of various interactions are key to the self-assembly of chiral structures. Herein, a ternary co-assembly consisting of cationic pillar[5]arenes (P5As), anionic ß-glucopyranoside (ßGlcD/ßGlcL), and Anderson-type polyoxometalates (POMs) were constructed. Through adjusting the stoichiometry of ßGlcD, the assemblies were effectively controlled to form hierarchical nano-leaf assemblies with twisted nanoribbons in a homochiral direction. The co-assemblies exhibit strong Cotton effects, and successfully induced the chirality of Anderson-type POMs. More interestingly, by changing the central metal in Anderson-type POMs (XMo6 O24 3- (X=Cr, Al, and Ga)), even though the three clusters have the same numbers of charge and size, the hierarchical chirality of the related assemblies varied in the morphology of the assemblies and the Cotton effect in the CD spectra. Results in theoretical calculations and ITC titration indicates that the tiny difference in long-range electrostatic interaction would result in the anion recognition of POMs, modulated by ßGlcD through host-guest inclusion and hydrogen bonding in the assembly process.

OsDOF11 Promotes Crown Root Formation via Cytokinin in Oryza Sativa.

BACKGROUND: Crown root is the main part of root system, which performs an important role in rice growth and development, especially in nutrition and water assimilation. Previously, we reported negative feedback regulation loop between Oryza sativa DNA BINDING WITH ONE FINGER 11 (OsDOF11) and cytokinin by Oryza sativa CYTOKININ OXIDASE/DEHYDROGENASE 4 (OsCKX4) in rice development. METHODS: Reverse transcription quantitative RT-PCR analyses was used to analyze the related gene transcript level. Nitrogen and hormone were measured by CHN-Nitrogen analyser and Liquid chromatography mass spectrometer, respectively. Exogenous application of cytokinin and [13C] sucrose labeled stable isotope uptake experiments help us to explain the relationship between OsDOF11 and cytokinin. RESULTS: We demonstrate the role of OsDOF11 in root development. We note that the loss function of OsDOF11 displays the reduced crown roots number, low activity of nitrogen assimilation and low content of cytokinin and auxin. The expression level of WUSCHEL-related homeobox (OsWOX11), A-type response regulator 2 (OsRR2), OsRR3, and OsCKX4 were decreased in osdof11-1, as well as in OsDOF11 RNA interference 9 mutants (RNAi-9 lines). Through Exogenous application of multiple concentrations of cytokinin as treatment to osdof11-1 mutant, RNAi-9 lines, and wild type (WT). We found that the crown roots number of osdof11-1 plants were rescued as the cytokinin concentration increased gradually from 1 µM to 10 µM, but the effect was weaker in RNAi-9 line. And cytokinin inhibited sucrose uptake activity from Murashige-Skoog medium with 3.0% sucrose (MS30) by OsDOF11 in rice root. CONCLUSIONS: OsDOF11 promotes crown root formation via cytokinin in oryza sativa. These results provide a physiological basis for further analysis of the OsDOF11 function of in rice root development.

An Electrochemical Cholesteric Liquid Crystalline Device for Quick and Low-Voltage Color Modulation.

We demonstrate a method for fabricating a prototype reflective display device that contains cholesteric liquid crystal (LC) as an active component. The cholesteric LC is composed of a nematic LC 4'-pentyloxy-4-cyanobiphenyl (5OCB), redox-responsive chiral dopant (FcD), and a supporting electrolyte 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (EMIm-OTf). The most important component is FcD. This molecule changes its helical twisting power (HTP) value in response to redox reactions. Therefore, in situ electrochemical redox reactions in the LC mixture allow for the device to change its reflection color in response to electrical stimuli. The LC mixture was introduced, by a capillary action, into a sandwich-type ITO glass cell comprising two glass slides with patterned indium tin oxide (ITO) electrodes, one of which was coated with poly(3,4-ethylenedioxythiophene)-co-poly(ethylene glycol) doped with perchlorate (PEDOT+). Upon application of +1.5 V, the reflection color of the device changed from blue (467 nm) to green (485 nm) in 0.4 s. Subsequent application of 0 V made the device recover the original blue color in 2.7 s. This device is characterized by its fastest electrical response and lowest operating voltage among any previously reported cholesteric LC device. This device could pave the way for the development of next generation reflective displays with low energy consumption rates.

Guest Controlled Pillar[5]arene and Polyoxometalate Based Two-Dimensional Nanostructures toward Reversible Iodine Capture.

The two-dimensional (2D) nanostructures comprised of polyoxometalate based building blocks are of great value in nanoarchitectures, which have unique properties and widespread potential applications, but it is still challenging in mature preparation. Herein a new strategy to build Cr(III) centered Anderson type polyoxometalate 2D nanostructures based on the modulation of host-guest interaction between cationic pillar[5]arenes and sodium dodecyl sulfonate (SDS) in aqueous media was exploited in this work. Through regulating stoichiometry of SDS, the morphology of assemblies vary from nanobones to 2D nanosheets. The fine assembled structure was discovered by combined 1H NMR, SAXS, and element analyses. The nanomaterials can be used as adsorbents for I2 in various solutions, including n-hexane, cyclohexane, water, and chloroform, where the polyoxometalates play a key role in the effective adsorption of iodine since they can expand the interspace between pillar[5]arenes in the as-prepared nanostructure. Furthermore, such adsorbents are easily regenerated and reused as iodine can be released spontaneously from nanobones@I2 and nanosheets@I2 solids when being immersed in dimethyl sulfoxide.

A Supramolecular Catalyst Self-Assembled From Polyoxometalates and Cationic Pillar[5]arenes for the Room Temperature Oxidation of Aldehydes.

Oxidizing aldehydes to generate carboxylic acids is a crucial reaction in nature and in chemical industry. The aldehyde oxidation, an easily achieved process in liver cells, is inert toward autoxidation in industrial production and difficultly achieved under enzymatic condition (in water, at pH 7, at room temperature). Herein, we prepared a supramolecular catalyst which are nanospheres assembled in aqueous media by chromium centered Anderson polyoxometalates Na3[CrMo6O18(OH)3] (namely, CrMo6) and cationic pillar[5]arenes (namely, P5A) with 10 positive charges which can be used as the phase transfer catalysts (PTCs). This supramolecular catalyst was exploited on aldehydes oxidation under enzymatic condition with relatively good conversion. Through DLS monitoring, the diameters of nanospheres were variable while changing the charge ratios of the ionic complexes (P5A-CrMo6), and it is probably because of the closer charge ratios causing the more compact assemblies. Also, the nano-morphologies were monitored by TEM and SEM, and the nanostructures were characterized by zeta potential, the X-ray energy-dispersive spectroscopy (EDS), elemental analysis.

The proton-controlled synthesis of unprecedented diol functionalized Anderson-type POMs.

By addition of excess acid into the reaction mixture, a series of organically-derived Anderson-type polyoxometalates, {[R1CR2(CH2O)2]CrMo6O18(OH)4}(3-), with diols as the ligands are reported herein. Such a diol functionalization mode not only works for some specific triol ligands but also can readily be extended to the diol ligands, which will greatly enrich the species of alkoxo-derivatized Anderson POM clusters.