A Method of Discharge Estimation Based on Lateral Velocity Distribution Function Applied To Ultrasonic Velocity Meter System

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Butterfly-Shaped Diphenylpyrimidine Molecule: Tunable Photophysical Properties by Molecular Self-Assembly Pathways

To understand the relationships between chemical structures, molecular packing structures, and photophysical properties of organic materials, a butterfly shaped diphenylpyrimidine molecule (abbreviated as DPP-6C12) was newly synthesized [Park, M.; Choi, Y.-J.; Kim, D.-Y.; Hwang, S.-H.; Jeong, K.-U. Cryst. Growth Des. 2015, 15, 900–906]. By breaking the molecular symmetry and coplanarity of DPP-6C12, peculiar monotropic phase transitions were observed. Based on two-dimensional wide-angle X-ray diffraction and selected area electron diffraction, the molecular packing structures of ordered phases were identified, which were further confirmed by the computer simulations in the real and reciprocal spaces. Finally, we demonstrated that the photophysical properties of DPP-6C12 can be tuned by controlling the molecular packing structures with simple thermal treatments

Characteristics of Atmospheric Pollutants in Paddy and Dry Field Regions: Analyzing the Oxidative Potential of Biomass Burning

This study aimed to identify the characteristics of atmospheric pollutants emitted by agricultural activities and to evaluate factors that may cause harm to human health. For the research, atmospheric pollutants were measured over the course of a year in representative rice farming and field crop farming areas in South Korea. The results confirmed that the characteristics of atmospheric pollutants in agricultural areas are influenced by the nature of agricultural activities. Specifically, when comparing rice paddies and field crop areas, during summer, the correlation between oxidative potential and levoglucosan—a marker for biomass burning—weakens due to less burning activity in the rice-growing season, leading to lower oxidative potential despite different PM2.5 across areas. The study also finds that methyl sulfonic acid, indicating marine influence, plays a big role in keeping oxidative potential low in summer. This suggests that the main causes of PM2.5-related health risks in the area are from biomass burning and external sources, with burning being a significant factor in increasing oxidative potential. Based on these results, it is hoped that measures can be taken in the future to reduce atmospheric pollutants in agricultural areas

Unique Monotropic Phase Transition Behaviors of a Butterfly-Shaped Diphenylpyrimidine Molecule

The physical properties of two-dimensional disc-shaped aromatic carbon molecules strongly depend on the molecular packing structures. A butterfly-shaped diphenylpyrimidine molecule (DPP-6C12) was synthesized by covalently attaching two tridodecyl benzoate tails (6C12) at the both sides of the diphenylpyrimidine (DPP) moiety. Unique phase transition behaviors of DPP-6C12 and their origins were investigated with the combined techniques of thermal, scattering, spectroscopic, and microscopic analyses. On the basis of the experimental results and analyses, it was realized that a butterfly-shaped DPP-6C12 formed three ordered phases: a plastic crystal phase (PK), a crystal phase (K), and a liquid crystal phase (Φ). By breaking the molecular symmetry and coplanarity of DPP-6C12, peculiar monotropic phase transition behaviors were observed. The stable Φ mesophase was formed either by a slow heating above the metastable PK phase or by an isothermal annealing between <i>T</i>_Φ and <i>T</i>_K. The stable K phase was only formed by a slow heating from the preordered Φ mesophase, and the formation of the K phase directly from the isotropic state (I) was forbidden because the nucleation barrier from I to K was too high to be overcome via thermal annealing

Photoresponsive Carbohydrate-based Giant Surfactants: Automatic Vertical Alignment of Nematic Liquid Crystal for the Remote-Controllable Optical Device

Photoresponsive carbohydrate-based giant surfactants (abbreviated as CELA<i>_n</i>D-OH) were specifically designed and synthesized for the automatic vertical alignment (VA) layer of nematic (N) liquid crystal (LC), which can be applied for the fabrication of remote-controllable optical devices. Without the conventional polymer-based LC alignment process, a perfect VA layer was automatically constructed by directly adding the 0.1 wt % CELA₁D-OH in the N-LC media. The programmed CELA₁D-OH giant surfactants in the N-LC media gradually diffused onto the substrates of LC cell and self-assembled to the expanded monolayer structure, which can provide enough empty spaces for N-LC molecules to crawl into the empty zones for the construction of VA layer. On the other hand, the CELA₃D-OH giant surfactants forming the condensed monolayer structure on the substrates exhibited a planar alignment (PA) rather than a VA. Upon tuning the wavelength of light, the N-LC alignments were reversibly switched between VA and PA in the remote-controllable LC optical devices. Based on the experimental results, it was realized that understanding the interactions between N-LC molecules and amphiphilic giant surfactants is critical to design the suitable materials for the automatic LC alignment

Hierarchical Striped Walls Constructed by the Photopolymerization of Discotic Reactive Building Blocks in the Anisotropic Liquid Crystal Solvents

A triphenylene-based reactive mesogenic molecule (abbreviated as HABET) was newly designed and synthesized as a programmed building block to construct the striped walls by the photopolymerization in the anisotropic liquid crystal (LC) solvents. On the basis of thermal, scattering and microscopic analyses, it was found that HABET formed three ordered structures: a columnar hexagonal LC phase (Φ_H), a tilted columnar hexagonal LC phase (Φ_T) and a highly ordered columnar oblique crystal phase (Φ_OK). The microscopic molecular orientations in the hierarchical superstructures were controlled in the anisotropic LC solvents with the help of surface anchoring forces, while the dimensions of the striped wall morphologies were determined by the patterned photomasks. The long axis of self-assembled columns in the striped walls was perpendicular to the surface alignment direction regardless of the photomask direction. Additionally, it was realized that the shapes of water drops as well as the surface water contact angles can be tuned by the hierarchical superstructures and morphologies of the polymerized HABET networks. The anisotropic hierarchical superstructures and morphologies concurrently fabricated during the polymerization in the anisotropic LC medium can offer a potential pathway for liquid transportation in the microfluidic devices

Construction of Polymer-Stabilized Automatic MultiDomain Vertical Molecular Alignment Layers with Pretilt Angles by Photopolymerizing Dendritic Monomers under Electric Fields

The synthesized itaconic acid-based dendritic amphiphile (Ita3C₁₂) monomers and the methacryl polyhedral oligomeric silsesquioxane (MAPOSS) cross-linkers were directly introduced for the construction of automatic vertical alignment (auto-VA) layers in the host nematic liquid crystal (NLC) medium. The auto-VA layer can be stabilized by irradiating UV light. For the automatic fabrication of a polymer-stabilized multidomain VA (PS auto-MDVA) layer with a pretilt angle, Ita3C₁₂ and MAPOSS were photopolymerized under the electric field by irradiating UV light on the multidomain electrode cell. Mainly because of the pretilted NLC at zero voltage, the electro-optic properties of the PS auto-MDVA cell were dramatically improved. From the morphological observations combined with surface chemical analyses, it was found that various sizes of protrusions on the solid substrates were automatically constructed by the two-step mechanisms. We demonstrated the PS auto-MDVA cell with the enhancement of electro-optic properties as a single-step process and investigated how the protrusions were automatically developed during the polymer stabilization

Pyrene-Based Asymmetric Supramolecule: Kinetically Controlled Polymorphic Superstructures by Molecular Self-Assembly

To understand the kinetically controlled polymorphic superstructures of asymmetric supramolecules, a pyrene-based asymmetric supramolecule (abbreviated as Py3M) was newly synthesized by connecting two pyrene headgroups (Py) to a biphenyl-based dendritic tail (3M) with an iso­phthala­mide connector. On the basis of thermal, microscopic, spectroscopic, and scattering results, it was realized that Py3M exhibited the monotropic phase transition between a stable crystalline phase (K1) and a metastable crystalline phase (K2). This monotropic phase transition behavior was mainly originated from the competitions of intra- and intermolecular interactions (π–π interactions and hydrogen bonds) as well as from the nanophase separations. From the two-dimensional (2D) wide-angle X-ray diffraction patterns and transmission electron microscopy images of the self-assembled Py3M superstructures, it was found that Py3M formed two synclinically tilted crystalline superstructures: the 6.75 and 4.4 nm periodicities of layered structures for K1 and K2 phases, respectively. The stable K1 phase was predominantly induced by the π–π interactions between pyrenes, while the intermolecular hydrogen bonds between iso­phthala­mides were the main driving forces for the formation of the metastable K2 phase. Ultraviolet–visible and photoluminescence experiments indicated that the photophysical properties of Py3M were directly related to their molecular packing superstructures

Azobenzene Molecular Machine: Light-Induced Wringing Gel Fabricated from Asymmetric Macrogelator

To develop light-triggered wringing gels, an asymmetric macrogelator (1AZ3BP) was newly synthesized by the chemically bridging a photoisomerizable azobenzene (1AZ) molecular machine and a biphenyl-based (3BP) dendron with a 1,4-phenylenediformamide connector. 1AZ3BP was self-assembled into a layered superstructure in the bulk state, but 1AZ3BP formed a three-dimensional (3D) network organogel in solution. Upon irradiating UV light onto the 3D network organogel, the solvent of the organogel was squeezed and the 3D network was converted to the layered morphology. It was realized that the metastable 3D network organogels were fabricated mainly due to the nanophase separation in solution. UV isomerization of 1AZ3BP provided sufficient molecular mobility to form strong hydrogen bonds for the construction of the stable layered superstructure. The light-triggered wringing gels can be smartly applied in remote-controlled generators, liquid storages, and sensors