Cryopreservation of cultivated and wild potato varieties by droplet vitrification: effect of subculture of mother-plants and of preculture of shoot tips

In this paper, we studied the effect of subculture of mother-plants and of preculture of shoot tips of two potato varieties (Dejima, cultivated and STN13, wild) cryopreserved using the droplet-vitrification technique. The subculture conditions (light intensity, aeration and planting density) significantly affected survival of both non-cryopreserved and cryopreserved shoot-tips in both varieties. The subculture duration and the position of the shoot tips on the axis of the in vitro plantlets had a significant (P<0.0001) effect on survival of cryopreserved shoot tips. The optimal subculture duration was 7 and 5 weeks and the optimal size of shoot tips was 1.5-2.0 and 1.0-1.5 mm for var. Dejima and STN13, respectively. Survival of cryopreserved shoot tips was influenced by the sucrose concentration in the preculture medium and the preculture duration. The highest survival of cryopreserved shoot tips was observed after preculture with 0.3 M sucrose for 8 h followed by 0.7 M sucrose for 18 h. These results indicate that the parameters of the subculture of mother-plants and of preculture of shoot tips should be carefully optimized, especially in the case of wild species.     

Study of Nanocrystalline BiMnO3‐‐PbTiO3: Synthesis,Structural Elucidation,and Magnetic Characterization of the Whole Solid Solution

In the last ten years, the study and the search for new multiferroic materials have been a major challenge due to their potential applications in electronic technology. In this way, bismuth‐containing perovskites (BiMO₃), and particularly those in which the metal M position is occupied by a magnetically active cation, have been extensively investigated as possible multiferroic materials. From the point of view of synthesis, only a few of the possible bismuth‐containing perovskites can be prepared by conventional methods but at high pressures. Herein, the preparation of one of these potential multiferroic systems, the solid solution xBiMnO₃‐(1?x)PbTiO₃ by mechanosynthesis is reported. Note that this synthetic method allows the oxides with high x values, and more particularly the BiMnO₃ phase, to be obtained as nanocrystalline phases, in a single step and at room temperature without the application of external pressure. These results confirm that, in the case of Bi perovskites, mechanosynthesis is a good alternative to high‐pressure synthesis. These materials have been studied from the point of view of their structural characteristics by precession electron diffraction and magnetic property measurements.     

A Super-Wide Bore DNP System for Multiple Sample Polarization: Cryogenic Performance and Polarization at Low Temperature

The volume of polarized sample and the delay required between successive polarizations of samples represent serious constraints for dynamic nuclear polarization (DNP) applications. With these limitations in mind, a DNP polarizer, based on a super-wide bore (150-mm diameter) vertical magnet operating at 3.35?T, was designed. The working diameter for loading/unloading samples is equal to 46?mm and the microwave cavity can accommodate up to three samples. The cryostat can be cooled to 4.2?K in typically 2?h and filled with liquid helium in 1?h. Once filled with liquid helium, the cryostat hold time is on the order of 4?h and a minimum temperature of 1.19?K can be reached. In situ polarization levels at low temperature were measured between 5 and 10?% in single and multiple samples of ¹³C-labeled urea and glycine.     

π‐Expanded α,β‐Unsaturated Ketones: Synthesis,Optical Properties,and Two‐Photon‐Induced Polymerization

A library of π‐expanded α,β‐unsaturated ketones was designed and synthesized. They were prepared by a combination of Wittig reaction, Sonogashira reaction, and aldol condensation. It was further demonstrated that the double aldol condensation can be performed effectively for highly polarized styrene‐ and diphenylacetylene‐derived aldehydes. The strategic placement of two dialkylamino groups at the periphery of D ‐π‐A‐π‐D molecules resulted in dyes with excellent solubility. These ketones absorb light in the region 400–550 nm. Many of them display strong solvatochromism so that the emission ranges from 530–580 nm in toluene to the near‐IR region in benzonitrile. Ketones based on cyclobutanone as central moieties display very high fluorescence quantum yields in nonpolar solvents, which decrease drastically in polar media. Photophysical studies of these new functional dyes revealed that they possess an enhanced two‐photon absorption cross section when compared with simpler ketone derivatives. Due to strong polarization of the resulting dyes, values of two‐photon absorption cross sections on the level of 200–300 GM at 800 nm were achieved, and thanks to that as well as the presence of the keto group, these new two‐photon initiators display excellent performance so that the operating region is 5–75 mW in some cases.     

Structure of Diacetato bis (2,4,6 Trimethyl Pyridine) Copper(II)

(2.4.6 trimethyl pyridine)₂ Cu(CH₃COO)₂ has been obtained as violet needles by slow evaporation. The crystals belong to the monoclinic system, space group P2_1/C with two molecules in a unit cell of dimension: a = 7.842 (1), b = 16.384 (2), c = 8.320 (2) Å, β = 101.91 (1)°. The structure was solved by heavy atom method and refined by a least squares method (R = 0.029). The coordination of copper is 4 + 2. The atom arrangements of this structure is very near to the copper acetate one solvated by one water molecule and two 3.4 dimethyl pyridine molecules.