Multiple Shape Manipulation of Azobenzene-Containing Polyimide by Combining Shape Memory Effect, Photofixity, and Photodeformation.

The integration of different shape manipulation could greatly expand the versatility and functionality of smart materials, for which the achievement of synergism of different shape control is crucial. Here, we seek to create one kind of polyimide with integrated multiple shape manipulations by constructing the chemical network bearing azobenzene as a side chain. Trifunctional cross-linkers serving as net points of the chemical network render polyimide thermal-induced shape memory effects, which enables shape transformation. Azobenzene as a photoresponsive group is employed to achieve the photofixity and reversible photodeformability. Such photosensitive behaviors are independent of molecular prealignment and remain available after thermally shaping and fixing. As a result, these noninterfering performances induced by heat and light allow us to arbitrarily combine them to meet different needs. By integrating different shape manipulations, various shape changes and functional execution are conveniently achieved. The combination of the shape memory effect with photofixity enables the setting of diverse shapes, while the merging of it with reversible deformation facilitates the construction of actuators capable of executing functions. This study provides a new approach for the preparation of multifunctional actuators and has potential applications in the field of intelligent drivers.

Photovoltaic properties in an orthorhombic Fe doped KTN single crystal.

Since the domain wall photovoltaic effect (DW-PVE) is reported in BiFeO3 film, the investigations on photovoltaic properties in ferroelectrics have appealed more and more attention. In this work, we employed two Fe doped KTa1-xNbxO3 (Fe:KTN) single crystals in tetragonal phase and orthorhombic phase, respectively, possessing similar net polarization along [001]C direction, to quantize the contribution on photovoltaic properties from bulk photovoltaic effect (BPVE) and DW-PVE in Fe:KTN. The results show that there are significant enhancements of open-circuit voltages (VOC = -6.0 V, increases over 440%) and short-circuit current density (JSC = 18.5 nA cm-2, increases over 1580%) in orthorhombic Fe:KTN with engineer-domain structure after poled, corresponding to 14.2 mV and 2.2 mV for the single domain wall and bulk region under illumination of 405 nm light (100 mW). It reveals that DW-PVE plays a major role in KTN-based ferroelectrics, indicating an orthorhombic Fe:KTN single crystal is one of the potential photovoltaic materials.

A novel approach for the removal of radiocesium from aqueous solution by ZSM-5 molecular sieve.

Finding an approach for pretreatment of radionuclides from contaminated water are interesting topics of research. In present work, the ZSM-5 molecular sieve was characterized with different techniques such as zeta potential, SEM, FT-IR and XRD to clarify the surface properties of sample and applied as a sorbent to concentrate and recover Cs(I) from aqueous solution. The effect of environmental conditions such as contact time, ionic strength, content of sorbent and solution pH on Cs(I) uptake were optimized using batch techniques. Different kinetic and isotherm models were utilized to evaluate the experimental data and the correlation parameters were obtained. Based on the sorption/desorption experiment, it can be deduced that the ZSM-5 molecular sieve has potential application for the rapid and quantitative recovery of radiocesium from wastewater.

Analysis of Technetium Species and Fractions in Natural Seaweed Using Biochemical Separation and ICP-MS Measurement.

An extremely high accumulation and retention of technetium in marine plants, especially brown seaweed, makes it a unique bioindicator of technetium. In the present work, a novel approach was developed for the speciation analysis of technetium in seaweed, wherein a series of biochemical separations was exploited to isolate different species of technetium. Inductively coupled plasma mass spectrometry (ICP-MS) was applied for the measurement of 99Tc after thorough radiochemical preconcentration and purification. The results show that the distribution of technetium species in seaweed is relatively dispersive. Besides the inorganic species of TcO4-, most of technetium (>75%) combined with organic components of seaweed such as algin, cellulose, and pigment. This investigation could provide important fundamental knowledge for studying the processes and mechanisms of 99Tc accumulation in the natural seaweed.

Rare earth-modified kaolin/NaY-supported Pd-Pt bimetallic catalyst for the catalytic combustion of benzene.

A new type of porous kaolin/NaY composite (KL-NY) with a large specific surface area and large pore sizes was synthesized through a one-step crystallization process, and rare earth-modified KL-NY-supported Pd-Pt catalysts were studied for benzene combustion. The results indicated that the pore volume and specific surface area of KL-NY after calcination and crystallization were 0.298 cm(3)/g and 365 m(2)/g, respectively, exhibiting appropriate pore structure and good thermal stability. Catalysts with rare earth metals greatly enhanced the activity of Pd/KL-NY, and the addition of Pt and Ce into the Pd catalyst improved the catalytic activity as well as the stability. The catalyst with an optimal Ce content and Pt/Pd molar ratio (0.2%Pd-Pt (6:1)/6%Ce/KL-NY) demonstrated the best activity for the complete oxidation of benzene at 230 °C, and the catalyst above maintained the 100% benzene conversion for 960 h.

Dracotanosides A-D, spermidine glycosides from Dracocephalum tanguticum: structure and amide rotational barrier.

Four new spermidine glycosides, dracotanosides A-D (1-4), have been isolated from Dracocephalum tanguticum. These molecules represent the first spermidine glycosides from this plant genus. The structures, including absolute configurations, were determined by spectroscopic and chemical methods. The amide bond rotational barrier of aglycone 1a was calculated by density functional theory (DFT) computation.