Evidence of 3D Topological-Domain Dynamics in KTN:Li Polarization-Supercrystal Formation.

We experimentally and theoretically investigate thermal domain evolution in near-transition KTN:Li. Results allow us to establish how polarization supercrystals form, a hidden 3D topological phase composed of hypervortex defects. These are the result of six converging polarization vortices, each associated to one orientation of the 3D broken inversion symmetry. We also identify rescaling soliton lattices and domain patterns that replicate on different scales. Findings shed light on volume domain self-organization into closed-flux patterns and open up new scenarios for topologically protected noise-resistant ferroelectric memory bits.

Hot-Carrier Cooling Regulation for Mixed Sn-Pb Perovskite Solar Cells.

The rapid relaxation of hot carriers leads to energy loss in the form of heat and consequently restricts the theoretical efficiency of single-junction solar cells; However, this issue has not received much attention in tin-lead perovskites solar cells. Herein, tin(II) oxalate (SnC2O4) is introduced into tin-lead perovskite precursor solution to regulate hot-carrier cooling dynamics. The addition of SnC2O4 increases the length of carrier diffusion, extends the lifetime of carriers, and simultaneously slows down the cooling rate of carriers. Furthermore, SnC2O4 can bond with uncoordinated Sn2+ and Pb2+ ions to regulate the crystallization of perovskite and enable large grains. The strongly reducing properties of the C2O4 2- can inhibit the oxidation of Sn2+ to Sn4+ and minimize the formation of Sn vacancies in the resulting perovskite films. Additionally, as a substitute for tin(II) fluoride, the introduction of SnC2O4 avoids the carrier transport issues caused by the aggregation of F- ions at the interface. As a result, the SnC2O4-treated Sn-Pb cells show a champion efficiency of 23.36%, as well as 27.56% for the all-perovskite tandem solar cells. Moreover, the SnC2O4-treated devices show excellent long-term stability. This finding is expected to pave the way toward stable and highly efficient all-perovskite tandem solar cells.

Intense Wave Formation from Multiple Soliton Fusion and the Role of Extra Dimensions.

We experimentally and numerically explore the role of dimensionality in multiple (three or more) soliton fusion supported by nonreciprocal energy exchange. Three-soliton fusion into an intense wave is found when an extra dimension, with no broken inversion symmetry, is involved. The phenomenon is observed for 2+1D spatial waves in photorefractive crystals, where solitons are supported by a spatially local saturated Kerr-like self-focusing and fusion is driven by the leading nonlocal correction, the spatial analog of the nonlinear Raman effect.

Homologous Overexpression of Diacylglycerol Acyltransferase in Oleaginous Fungus Mucor circinelloides WJ11 Enhances Lipid Accumulation under Static Solid Cultivation.

Diacylglycerol acyltransferase (DGAT) catalyzes the binding of acyl-CoA to diacylglycerol to form triacylglycerol (TAG). Previous studies strongly indicate that DGAT2, rather than DGAT1, is crucial for TAG accumulation in the oleaginous fungus Mucor circinelloides. To increase the lipid content of M. circinelloides WJ11, McDGAT2 was overexpressed by homologous recombination; compared to the control strain Mc2075, transformants McDGAT2d showed a significant increase in biomass for both spores and mycelia (from 87.7 to 101.2 mg/g in spores and from 75.6 to 93.1 mg/g in mycelia). McDGAT2 overexpression under static solid fermentation gave a greater boost to lipid accumulation in mycelia than in spores. Total fatty acid content in mycelia increased by 68.0% (from 13.6 to 22.8%) and in spores by 26.3% (from 10.6 to 13.4%). However, under submerged fermentation, the lipid content of McDGAT2d was the same as the control, while biomass was slightly reduced. Transcriptomics showed that NADPH was derived mainly from the pentose phosphate pathway, acetyl-CoA was from multiple pathways, and leucine metabolism played an important role in substrate supply for fatty acid biosynthesis. Static solid fermentation may be the more suitable fermentation method for microbial oil production by filamentous fungi due to its lower fermentation costs.

Overexpression of Shinorhizobium meliloti flavohemoglobin improves cell growth and fatty acid biosynthesis in oleaginous fungus Mucor circinelloides.

Oxygen availability is a limiting factor for lipid biosynthesis in eukaryotic microorganisms. Two bacterial hemoglobins from Vitreoscilla sp. (VHb) and Shinorhizobium meliloti (SHb), which deliver oxygen to the respiratory chain to produce more ATP, were introduced into Mucor circinelloides to alleviate oxygen limitation, thereby improving cell growth and fatty acid production. The VHb and SHb genes were integrated into the M. circinelloides MU402 genome by homologous recombination. VHb and SHb protein expression was verified by carbon monoxide difference spectrum analysis. The biomass was increased by ~ 50% in the strain expressing SHb compared with VHb. The total fatty acid (TFA) content of the strain expressing SHb reached 15.7% of the dry cell weight (~ 40% higher than that of the control strain) during flask cultivation. The biomass and TFA content were markedly increased (12.1 g/L and 21.1% dry cell weight, respectively) in strains expressing SHb than strains expressing VHb during fermenter cultivation. VHb and SHb expression also increased the proportion of polyunsaturated fatty acids. Overexpressed bacterial hemoglobins, especially SHb, increased cell growth and TFA content in M. circinelloides at low and high aeration, suggesting that SHb improves fatty acid production more effectively than VHb in oleaginous microorganisms.

Evidence of Chaotic Dynamics in Three-Soliton Collisions.

We observe chaotic optical wave dynamics characterized by erratic energy transfer and soliton annihilation and creation in the aftermath of a three-soliton collision in a photorefractive crystal. Irregular dynamics are found to be mediated by the nonlinear Raman effect, a coherent interaction that leads to nonreciprocal soliton energy exchange. Results extend the analogy between solitons and particles to the emergence of chaos in three-body physics and provide new insight into the origin of the irregular dynamics that accompany extreme and rogue waves.

Direct Observation of Fractal-Dimensional Percolation in the 3D Cluster Dynamics of a Ferroelectric Supercrystal.

We perform percolation analysis of crossed-polarizer transmission images in a biased nanodisordered bulk KTN:Li perovskite. Two distinct percolative transitions are identified at two electric field thresholds. The low-field transition involves a directional fractal chain of dimension D=1.65, while the high-field transition has a dimension D>2. Direct cluster imaging in the volume is achieved using high-resolution orthographic 3D projections based on giant refraction. Percolation is attributed to a full-3D domain reorientation that mediates the transition from a ferroelectric supercrystal state to a disordered domain mosaic.

Soliton Maxwell demons and long-tailed statistics in fluctuating optical fields.

We demonstrate experimentally in biased photorefractive crystals that collisions between random-amplitude optical spatial solitons produce long-tailed statistics from input Gaussian fluctuations. The effect is mediated by Raman nonlocal corrections to Kerr self-focusing that turn soliton-soliton interaction into a Maxwell demon for the output wave amplitude.

Multi-responsive supramolecular organogel with a crystalline-like structure.

A multi-responsive cyclodextrin-based organogel with a crystalline-like structure is first reported. An amount of ß-cyclodextrin (ß-CD) and lithium chloride (LiCl) was added into N,N-dimethylformamide (DMF), and the system obtained could transform instantly from a transparent solution into a gel state by introducing ethylene diamine (EDA), and then the gel could turn into another precipitate-like gel by undergoing a heating-cooling process. Among a series of aliphatic amines, only EDA was found to be able to induce the gel formation. Both the gels possess crystalline-like structures in their morphology with sheet-like layers, in a highly-ordered channel-type packing mode, which were proved by OM, SEM, XRD, and FT-IR measurements. Furthermore, the gel could respond to H(+) and Cu(2+) by transforming into an amorphous precipitate. This research may pave the way for the design of novel smart materials.

Novel double phase transforming organogel based on ß-cyclodextrin in 1,2-propylene glycol.

This paper describes a novel double phase transforming organogel (gel-sol-gel') composed of nontoxic ß-cyclodextrin, potassium carbonate, and 1,2-propylene glycol. The gel-sol-gel' transforming processes are followed by a reversible gel-sol transforming process and an irreversible sol-gel' transforming process based on heating. The gel-sol-gel' transformation is accompanied by microstructure changes from nanospheres to nanorods. K(2)CO(3) plays a key role in associating supramolecular architectures of ß-cyclodextrin into a three-dimensional network. This work may bring further applications in the areas of smart materials, drug delivery systems, and biomaterials.

Ultraviolet band edge photorefractivity in LiNbO3:Sn crystals.

The ultraviolet (UV) band edge photorefractivity of Sn-doped LiNbO(3) (LN:Sn) at 325 nm has been investigated. A sharp decrease of beam distortion, which is accompanied by a significant increase in the photoconductivity, is observed in LN:Sn crystals with Sn-doping concentrations at or above 2.0 mol%. The diffraction efficiency, the holographic recording sensitivity and response rate, and the two-wave coupling gain coefficient are greatly enhanced when the Sn-doping concentration reaches 2.0 mol% or more. Unlike LiNbO(3) doped with Hf in which the UV gratings can be erased easily by a red beam, the UV gratings in LN:Sn can withstand long-term red beam illumination. Electrons are determined to be the dominant light-induced charge carriers responsible for the UV band edge photorefraction. The observed enhancement on the UV band edge photorefractivity is found to be associated with the showup of an absorption band around 325 nm in LN:Sn crystals with Sn-doping concentrations at or above 2.0 mol%.

Controlled transformation from nanorods to vesicles induced by cyclomaltoheptaoses (ß-cyclodextrins).

A modified cyclomaltoheptaose (ß-cyclodextrin) containing an anthraquinone moiety, mono[6-deoxy-N-n-hexylamino-(N'-1-anthraquinone)]-ß-cyclodextrin (1), which can self-assemble into nanorods in aqueous solution, was synthesized. Interestingly, upon the addition of natural cyclodextrin, the nanorods could transform into bilayer vesicles, which were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), dynamic light scattering (DLS), and epi-fluorescence microscopy (EFM). A transformation mechanism is suggested based on the results of (1)H NMR, 2D NMR ROESY, FTIR, and UV-vis spectra. The response of the vesicles to changing pH and adding Cu(2+) was also tested. Our research may pave the way to the development of new intelligent materials and biomaterials.

Successively-responsive drug-carrier vesicles assembled by 'supramolecular amphiphiles'.

Novel vesicles assembled by 'supramolecular amphiphiles' based on the inclusion complexes between 1 and ß-CDs (ß-CD and HP-ß-CD) were found to carry drugs and be successively-responsive to external stimuli for the first time. These vesicles were observed by TEM and SEM and confirmed by DLS. The formation patterns of 'supramolecular amphiphiles' characterized by UV and NMR can be controlled by choosing different hosts. Unlike traditional drug delivery and releasing systems, the 'useless' inclusion complexes 1·ß-CDs in thinking formula can assemble into vesicles to carry both cytotoxic 1 and drugs (piroxicam and ampicillin) at one time, confirmed by TEM, UV, and NMR data. Also the vesicles assembled by 1·ß-CDs can be successively-responsive to acidifying and oxidizing, and release drugs and cytotoxic compounds in order.

Reversible vesicles based on one and two head supramolecular cyclodextrin amphiphile induced by methanol.

Reversible vesicles based on supramolecular inclusion of hydroxypropyl-beta-CD (HPbetaCD) and N,N'-bis(ferrocenylmethylene)-diaminohexane (BFD) were prepared in water and methanol-water mixtures. The inclusion stoichiometry of HPbetaCD with BFD was in a molar ratio of 2:1, which could be named as 'two head' supramolecular amphiphile when the solvent was water. However, the inclusion stoichiometry of HPbetaCD with BFD would tend to be a molar ratio of 1:1 based on introduction of methanol to the solvent, especially when the volume ratio of methanol and water was more than 1:4, which could be named as 'one head' supramolecular amphiphile. The inclusion compounds could switch between 'one head' and 'two head' conformations by changing the methanol concentration of the solvents. The vesicles were also found to be responsive to the stimulus of external molecules. When the inclusion ability between HPbetaCD and an external guest was relatively stronger, the vesicles were easily destroyed. Furthermore, the vesicles disappeared after adding an oxidizing agent. NMR was used to confirm the conformation of the mixture of HPbetaCD and BFD in water. The structure and morphology of the vesicles were characterized by TEM and DLS. The vesicles may be used in smart materials, drug delivery and molecular recognition.

N-(Ferrocenylmethyl)-dodecan-1-amine.

The title compound, [Fe(C(5)H(5))(C(18)H(32)N)], was synthesized by the amination of ferrocenecarbaldehyde. In the complex, the two cyclo-penta-dienyl (Cp) rings are almost parallel with a dihedral angle of 1.36 (8)°, and are separated by a centroid-centroid distance of 3.299 (2) Å. In the crystal, adjacent mol-ecules are linked into a one-dimensional supra-molecular structure via weak C-H⋯π inter-actions between the Cp ring H atom and the Cp ring.

2-Isopropyl-3-methyl-quinoxaline 1,4-dioxide.

In the title compound, C(12)H(14)N(2)O(2), the quinoxaline ring system and the C atoms of the methylene and methyl substituents lie on a mirror plane. The crystal packing is stabilized by weak π-π inter-actions [centroid-centroid distance = 3.680 (7) Å].