Solvent-dependent fluorescence behaviour of imide-fused [n]phenacenes (n = 3, 5, 7).

Imide-fused [n]phenacenes (nPDIs, n = 3, 5, 7) were systematically synthesised and their electronic features were investigated by electrochemical and electronic spectral measurements. nPDIs showed two reduction waves attributed to formation of radical ions and dianions. 3PDI produced blue fluorescence independent of solvent polarity. In contrast, 5PDI and 7PDI displayed marked positive solvatofluorochromism due to intramolecular charge transfer characters between the imide moieties and phenacene π cores in the excited state. The spectral features were analyzed by the Lippert-Mataga relationship and theoretical calculations.

Thermosensitive visible-light-excited visible-/NIR-luminescent complexes with lanthanide sensitized by the π-electronic system through intramolecular H-bonding.

Visible-luminescent lanthanide (LnL) complexes with a highly planar tetradentate ligand were successfully developed for a visible-light solid-state excitation system. L was designed by using two 2-hydroxy-3-(2-pyridinyl)-benzaldehyde molecules bridged by ethylenediamine, which was then coordinated to a series of Ln ions (Ln = Nd, Sm, Eu, Gd, Tb, Dy, and Yb). From the measurement of single-crystal X-ray analysis of EuL, two phenolic O atoms and two imine N atoms in L were coordinated to the Eu ion, and each π-electronic system took coplanar with the edged-pyridine moiety through an intramolecular hydrogen bond. The enol group on the phenolic skeleton changed to the keto form, and the pyridine was protonated. Thus, intramolecular proton transfer occurred in L after the complexation. Other complexes take isostructure. The space group is P-1, and the c-axis shrinks with decreasing temperature without a phase transition in EuL. The yellow color caused by the planar structure of L can sensitize ff emission by visible light, and the luminescence color of each complex depends on central Ln ions. Furthermore, a phosphorescence band also appeared at rt with ff emission in LnL. Drastic temperature dependence of luminescence was clarified quantitatively.

Seasonal variation in the prevalence of Gram-negative bacilli in sputum and urine specimens from outpatients and inpatients.

Objectives: To determine whether the prevalence of gram-negative bacilli (GNB; Pseudomonas aeruginosa, Klebsiella pneumoniae, and Escherichia coli) in sputum and urine specimens from outpatients and inpatients differed by season and according to temperature and humidity changes. Methods: In this retrospective study, microbiologic data for adult patients from 2008 to 2019 were retrieved from the electronic database of a hospital in Japan. Data were categorized by specimen type (sputum and urine) and specimen collection (outpatient and inpatient). Associations between variables were assessed using Spearman's rank correlation coefficients. Differences between groups were assessed using Pearson's chi-square test and analysis of discrete variance. Results: Among inpatients, the frequencies of P. aeruginosa and K. pneumoniae isolation from sputum specimens were higher in summer and autumn. The frequency of P. aeruginosa isolation from urine specimens was higher in autumn. These seasonal trends were observed in specimens from both outpatients and inpatients. No seasonal trend was observed in the frequency of E. coli isolation. Mean monthly temperature was positively correlated with the frequency of isolating P. aeruginosa (r=0.2198, p=0.0081) and K. pneumoniae (r=0.3443, p=0.00002) from sputum as well as with the frequency of isolating K. pneumoniae (r=0.1905, p=0.0222) from urine. Mean monthly humidity was positively correlated with the frequency of isolating K. pneumoniae (r=0.2602, p=0.0016) from sputum. Conclusions: GNB were isolated more frequently in summer and autumn than in other seasons. These seasonal trends were observed for both outpatient and inpatient specimens. Seasonality should be considered for optimal infection control of GNB in hospitals.

Transparent dynamic metasurface for a visually unaffected reconfigurable intelligent surface: controlling transmission/reflection and making a window into an RF lens.

Reconfigurable intelligent surfaces (RISs) that dynamically manipulate scattered waves have attracted much attention regarding accommodating coverage holes in wireless communication systems using radio wave frequencies higher than millimeter waves. RISs generally actualized through metasurface technologies must be visually unaffected so that they can be installed in various locations such as existing walls and glass windows in environments where propagation should be controlled. We propose a novel method that dynamically controls scattering characteristics of metasurfaces while achieving a large area and high optical transparency. For transparency in the visible light range, we use transparent glass as a substrate and meshed metal patterns. Furthermore, by stacking a metasurface substrate onto another transparent substrate and controlling the interlayer distance, we achieve dynamic control of the scattered waves over a large area in the 28-GHz band. Fabricated prototypes successfully operate when switching transmission and reflection modes, exhibiting extremely low loss of less than -1 dB. In metasurface lenses that can be attached to glass windows in outdoor-to-indoor scenarios, the lens gain of 25.4 dB is achieved for a static lens, and dynamic switching operation between single focus and dual focus is also successfully verified for a dynamic lens.

Photochemical synthesis and device application of acene-phenacene hybrid molecules, dibenzo[n]phenacenes (n = 5-7).

Dibenzo[n]phenecenes (DBnPs, n = 5-7) were conveniently synthesised through Mallory photocyclization as the key step. Effective mobilities of single-crystal field-effect transistors of DBnPs were evaluated to demonstrate that C2h-symmetrical DB6P shows higher performance than C2v-symmetrical DB5P and DB7P.

Mechanomics Biomarker for Cancer Cells Unidentifiable through Morphology and Elastic Modulus.

Cellular mechanical properties are potential cancer biomarkers used for objective cytology to replace the current subjective method relying on cytomorphology. However, heterogeneity among intra/intercellular mechanics and the interplay between cytoskeletal prestress and elastic modulus obscured the difference detectable between malignant and benign cells. In this work, we collected high density nanoscale prestress and elastic modulus data from a single cell by AFM indentation to generate a cellular mechanome. Such high dimensional mechanome data was used to train a malignancy classifier through machine learning. The classifier was tested on 340 single cells of various origins, malignancy, and degrees of similarity in morphology and elastic modulus. The classifier showed instrument-independent robustness and classification accuracy of 89% with an AUC-ROC value of 93%. A signal-to-noise ratio 8 times that of the human-cytologist-based morphological method was also demonstrated, in differentiating precancerous hyperplasia cells from normal cells derived from the same lung cancer patient.

Bottlebrush polymer-reinforced transparent multiphase plastics with enhanced thermal stability.

Bottlebrush polymers (BPs) are highly tunable with regard to their glass transition temperature, refractive index, and shape. Herein, well-defined BPs were implemented as soft fillers to toughen multiphase plastics without loss of transparency and thermal stability, providing superior fracture toughness than a conventional linear polymer (LP). This study discloses a novel application of BPs and paves the way toward their further development.

Multiscale analysis of mechanical behavior of multilayer steel structures fabricated by wire and arc additive manufacturing.

The mechanical behavior of multilayer steel structures fabricated via wire and arc additive manufacturing (WAAM) has been investigated from the multiscale perspective. The multimaterial WAAM approach can control a heterogeneous structure and improve its mechanical properties. In this study, WAAM equipment based on plasma arc welding was used to fabricate two pairs of single- and duplex-phase multilayer steel structures using austenitic and martensitic stainless steel wires. The heterogeneity of these structures was characterized through micro-indentation tests. In addition, tensile tests of the multilayer structures were conducted to evaluate the effect of heterogeneity on macroscopic material properties. The deformation behavior of the heterogeneous multilayer steel structures was investigated by comparison with the finite element simulations of tensile tests in which the finite element models were created according to the estimated local elastoplastic properties from the results of micro-indentation tests. The micro-indentation tests revealed that the local mechanical properties significantly change during WAAM in cases where martensitic stainless steel wire was used. Additionally, strain-induced transformation plasticity was particularly observed in duplex cases, caused by the metastable austenite phase formed according to the thermal history and through the mixing of alloy elements. Thus, the heterogeneity of the multilayer steel structures became more complicated than its design, and consequently, its macroscopic mechanical properties exceeded the upper and lower bounds of a micromechanic estimation. The results show the potential to fabricate a structure having a unique mechanical behavior via the multimaterial WAAM approach.

Stress mapping reveals extrinsic toughening of brittle carbon fiber in polymer matrix.

We conducted an in situ study on CFRP fracturing process using atomic-force-microscopy-based stress-sensitive indentation. Tensile stress distribution during fracture initiation and propagation was directly observed quantitatively. It led to a discovery that previously believed catastrophic fracture of individual carbon fiber develops in a controllable manner in the polymer matrix, exhibiting 10 times increase of fracture toughness. Plastic deformation in crack-bridging polymer matrix was accounted for the toughening mechanism. The model was applied to explain low temperature strength weakening of CFRP bulk material when matrix plasticity was intentionally 'shut down' by cryogenic cooling.

Timing of male territorial flight and foraging of the large carpenter bee Xylocopa appendiculata related to serotonin in the brain.

To determine how males of the large carpenter bee, Xylocopa appendiculata, maximize access to females while minimizing energy cost and acquiring energy for territorial flights, we investigated the times of territorial flights by males and foraging by males and females. Males were present continuously in territories from 8:00 to 12:00. They approached, chased, and excluded conspecific males from their territories. In the laboratory, males showed higher locomotor and flight activities in the morning and lower activities in the afternoon. Both males and females visited flowers from 8:00 to 16:00, but the most frequent visits were earlier in females (10:00-12:00) than in males (12:00-13:00). Relative body weights in territorial males often increased. These results indicate that the males time their territorial flights to maximize contact with females and obtain nectar as fuel between and after the territorial flights. The time-related territorial flight in males might be based on a time-keeping system in the brain. Brain levels of serotonin and its precursor tryptophan were significantly higher in males collected at 16:00 than at 11:00, suggesting a relation between time-related territorial flight and serotonin synthesis in the brain.

Alkyl Chain Length- and Polymorph-Dependent Photomechanochromic Fluorescence of Anthracene Photodimerization in Molecular Crystals: Role of the Lattice Stiffness.

Anthracene-pentiptycene hybrid systems 1-Cn, where n refers to the number of carbon atoms in the linear alkyl chain, crystallize in three different polymorphs, denoted Y (yellow), G (green), and B (blue) forms in terms of the fluorescence color. While all Y-form crystals show the same yellow-to-blue fluorescence color response to the photomechanical stress generated by the anthracene [4+4] photodimerization reaction, the four G forms exhibit distinct photomechanofluorochromism (PMFC): from green to blue for G-1-C4, to orange for G-1-C7, to red for G-1-C8, and to red then blue for G-1-C9, and the B forms show no photochromic activity. The intriguing RGB three-color PMFC and abnormal topochemical reactivity of G-1-C9 are attributed to inherent softness of the crystal lattice.

Combined Experimental and Theoretical Studies on Planar Chirality of Partially Overlapped C2-Symmetric [3.3](3,9)Dicarbazolophanes.

Partially overlapped dicarbazolophanes exhibit a planar chirality. In this study, C2-symmetrical [3.3](3,9)dicarbazolophane derivatives (CZ1-CZ3) have been optically resolved by preparative chiral high-performance liquid chromatography for the first time. In their circular dichroism (CD) spectra, moderate Cotton effects (CEs) were observed for their 1Lb and 1La transitions (|Δε| = 10-12 and 51-57 M-1 cm-1, respectively), while intense CEs were notified in their 1B transitions (|Δε| = 156-216 M-1 cm-1), absorption dissymmetry (gabs) factors being in orders of 10-2. Circularly polarized luminescence spectrum was also obtained for cyanamide derivative CZ1, with a comparative luminescence dissymmetry (glum) factor of 0.013. A computational investigation was applied to address the factors for such remarkable chiroptical responses in these dicarbazolophanes of planar chirality. Absolute configurations were unambiguously determined by the comparison of experimental and theoretical CD spectra, which was affirmed by the X-ray crystal structural analysis of enantiomerically pure sulfonamide derivative CZ2.

Facile synthesis of picenes incorporating imide moieties at both edges of the molecule and their application to n-channel field-effect transistors.

Picene derivatives incorporating imide moieties along the long-axis direction of the picene core (C n -PicDIs) were conveniently synthesized through a four-step synthesis. Photochemical cyclization of dinaphthylethenes was used as the key step for constructing the picene skeleton. Field-effect transistor (FET) devices of C n -PicDIs were fabricated by using ZrO2 as a gate substrate and their FET characteristics were investigated. The FET devices showed normally-off n-channel operation; the averaged electron mobility (µ) was evaluated to be 2(1) × 10-4, 1.0(6) × 10-1 and 1.4(3) × 10-2 cm2 V-1 s-1 for C4-PicDI, C8-PicDI and C12-PicDI, respectively. The maximum µ value as high as 2.0 × 10-1 cm2 V-1 s-1 was observed for C8-PicDI. The electronic spectra of C n -PicDIs in solution showed the same profiles irrespective of the alkyl chain lengths. In contrast, in thin films, the UV absorption and photoelectron yield spectroscopy (PYS) indicated that the lowest unoccupied molecular orbital (LUMO) level of C n -PicDIs gradually lowered upon the elongation of the alkyl chains, suggesting that the alkyl chains modify intermolecular interactions between the C n -PicDI molecules in thin films. The present results provide a new strategy for constructing a high performance n-channel organic semiconductor material by utilizing the electronic features of phenacenes.

Lanthanide Luminescence Enhancement of Core-Shell Magnetite-SiO2 Nanoparticles Covered with Chain-Structured Helical Eu/Tb Complexes.

Oligomeric-brush chains of helical lanthanide (Ln) complexes retain their structural and luminescent behavior after coating onto magnetic nanoparticles (MNPs) consisting of Fe3O4 covered with silicate. It is one of the type of bifunctional NPs exhibiting luminescence of Ln and superparamagnetism of Fe3O4. In comparison to a simple monolayer of complexes adsorbed on a modified surface, a layer made of luminescent chains allowed us to obtain a more intensive red/green luminescence originating from Eu3+/Tb3+ ions, and at the same time, no visible increase in particle size (compared to Fe3O4@silica particles) was observed. The luminescent properties of the Tb3+ complex were altered by MNPs; the decrease of the luminescence was not as large as expected, the excitation spectrum changed significantly, and the average luminescence lifetime was much longer at room temperature. Surprisingly, this phenomenon was not observed at 77 K and also did not occur for the Eu3+ complexes. The possibility to stack building blocks in a chain using complexes of different lanthanide ions can be used to design novel multifunctional nanosystems.

Blue fluorescence from N,O-coordinated BF2 complexes having aromatic chromophores in solution and the solid state.

We prepared amide-heterocycle (HC) compounds having various aromatic π-electron systems (Ar), such as phenyl, naphthyl, furyl, thienyl and phenanthryl moieties, and converted them as ligands to difluoroboronated complexes, Ar@HCs. Blue fluorescence from Ar@HCs was observed in solution and the solid state, and the fluorescence quantum yields (Φf) and lifetimes (τf) were determined. The Φf values in CHCl3 were as small as 0.1 except for the phenanthrene derivatives (0.4-0.6). Observation of the triplet-triplet absorption upon laser flash photolysis of Ar@HCs in solution indicated that the fluorescence process competes with intersystem crossing to the triplet state. Blue fluorescence in the solid state was observed with the Φf values of 0.3-0.7. Based on the crystallographic data, the relationship between the crystal structures and emission features of Ar@HCs in the solid state is discussed.

Suitability Evaluation of LaNi5 as Hydrogen-Storage-Alloy Actuator by In-Situ Displacement Measurement during Hydrogen Pressure Change.

The swelling ability of LaNi5 for application to hydrogen-storage-alloy (HSA) actuator is discussed through the measurement of the swelling ratio in hydrogen. The HSA actuator is driven by hydrogen pressure change causing the swelling of HSA. LaNi5 is one of the candidate materials for HSA actuators as well as palladium. Some prototypes of HSA actuators using LaNi5 have been fabricated; however, the kinetic swelling ability of LaNi5 itself has been not investigated. In this paper, the authors investigated the static and kinetic swelling ability of LaNi5 powder under hydrogen atmosphere. The results showed that the swelling ratio increased by 0.12 at the phase transition pressure. Response time decreased with an increase in the charged pressure during absorption, while it remained constant during discharge. Reaction kinetics revealed that these swelling behaviors were explained by hydrogen absorption and lattice expansion. The swelling ability of LaNi5 was also compared with that of palladium. The results show that LaNi5 swells 1.8 times more than palladium under 0.5 MPa. LaNi5 is suitable for an actuator driven repeatedly under more than the phase transition pressure. Palladium can be used for one-way-operation actuator even under 0.1 MPa since its response time during the evacuation was much longer than during the pressurization.

Stress dependence of indentation modulus for carbon fiber in polymer composite.

Elastic modulus measured through atomic force microscopy (AFM)-based indentation on single carbon fiber (CF) is found with dependence on lateral applied stress. An in situ indentation experiment inside a high-resolution transmission electron microscope was performed to quantitatively understand this phenomenon by observing microstructure change in the indented area. Change of graphitic basal plane misalignment angle during indentation was linked to a continuous change of modulus with the help of finite element simulation. The established relationship between modulus and indentation force was further used to calculate residual stress distribution in CF imbedded in a CF reinforced polymer composite using the AFM indentation technique. The stress-induced formation of nanoscale defects in the CF and their transformation into fracture were directly characterized.

Total Synthesis of Sialyl Inositol Phosphosphingolipids CJP-2, CJP-3, and CJP-4 Isolated from Feather Star Comanthus japonica.

The first total synthesis of three echinodermatous sialyl inositol phosphosphingolipids, which exhibit unusual neuritogenic activity in the absence of nerve growth factor, are reported. Highlights of the syntheses include 9- O-methylation on sialic acid, inter-residual amide bond formation between sialic acid residues, and highly stereo- and regioselective sialylation of inositol. A key phosphodiester linkage between the mono-, di-, and trisialyl inositols and ceramide was formed at a late state employing the phosphoramidite method.

Alkyl chain elongation and acyl group effects in a series of Eu/Tb complexes with hexadentate π-electronic skeletons and their enhanced luminescence in solutions.

Five Eu complexes with long alkyl chain groups, abbreviated as EuLCx ("x" indicates the number of methylene groups: x = 8, 12, 14, 18, and 22), were synthesized to evaluate their structural and luminescence properties in chloroform. The mother helicate Eu complex, EuL, which has two bipyridine moieties bridged by an ethylenediamine, has been previously reported. A reduced form in which the azomethine groups of L also coordinated to the Eu ion, EuLH, was newly prepared. EuLH also adopts a helicate molecular structure based on single crystal X-ray structural analysis. The amine hydrogens of the bridging ethylenediamine of LH are active sites for substitution and were exchanged with five different alkyl chains to form EuLCx. Luminescence band positions and shapes of EuLCx in chloroform were completely identical, with a quantum yield of 37.1 ± 1.2 and a lifetime of around 1.25 ms. This indicates that the environments surrounding the Eu ion in the various complexes are all similar. Luminescence quantum yields of TbLH and TbLC18 are also strengthened, 48.7% in acetonitrile and 55% in chloroform, respectively. Potential energy surfaces were also described by using density functional theory, suggesting the possibility of a 1 : 2 complex of Eu and the ligand as a main luminescent species in solutions. This 1 : 2 complexation forms Eu-oxygen coordination using acyl groups. It indicates that the acyl group modification results in a different structure from the mother complexes.

Blue Fluorescence from BF2 Complexes of N,O-Benzamide Ligands: Synthesis, Structure, and Photophysical Properties.

Small molecules having intense luminescence properties are required to promote biological and organic material applications. We prepared five types of benzamides having pyridine, pyridazine, pyrazine, and pyrimidine rings and successfully converted them into three types of the difluoroboronated complexes, Py@BAs, as novel blue fluorophores. Py@BA having a pyridine moiety (2-Py@BA) showed no fluorescence in solution, whereas Py@BAs of pyridazine and pyrazine moieties (2,3-Py@BA and 2,5-Py@BA, respectively) emitted blue fluorescence with quantum yields of ca. 0.1. Transient absorption measurements using laser flash photolysis of the Py@BAs revealed the triplet formation of 2,3- and 2,5-Py@BAs, while little transient signal was observed for 2-Py@BA. Therefore, the deactivation processes from the lowest excited singlet state of fluorescent 2,3- and 2,5-Py@BAs consist of fluorescence and intersystem crossing to the triplet state while that of the nonfluorescent Py@BA is governed almost entirely by internal conversion to the ground state. Conversely, in the solid state, 2-Py@BA emitted intense fluorescence with a fluorescence quantum yield as high as 0.66, whereas 2,3- and 2,5-Py@BAs showed fluorescence with quantum yields of ca. 0.2. The crystal structure of 2-Py@BA took a herringbone packing motif, whereas those for 2,3- and 2,5-Py@BAs were two-dimensional sheetlike. On the basis of the difference in crystal structures, the emission mechanism in the solid state was discussed.