Real-Time Monitoring of Adsorption-Induced Scrolling of Colloidal Inorganic Nanosheets.

Inorganic nanotubes have attracted much attention due to their unique physicochemical properties. Nanotubes can be prepared by scrolling exfoliated nanosheets under ambient conditions. However, how the nanosheet scrolled in its colloidal state has not been experimentally visualized. In this paper, we directly observed the scrolling process of nanosheets upon adsorption of organic cations. Exfoliated flat nanosheets of niobate and clay in aqueous colloids were found to scroll by adding organic cations, such as exfoliation reagents, to the colloids. Employment of cationic stilbazolium dye enabled in situ observation of the dye adsorption and scrolling by optical microscopy based on changes in color and morphology of the nanosheets. The scrolling was promoted for nanosheets adsorbed with a stilbazolium dye with a longer alkyl chain, suggesting that the interaction between the hydrophobic parts of the dye cations is the driving force of the scrolling. This finding should encourage research on the formation of nanotubes from nanosheets and also provides important guidelines for the selection of appropriate exfoliation reagents when exfoliating nanosheets from layered crystals.

Noninvasive Three-dimensional Assessment of Single Molecular Crystals Using Multiphoton Microscopic Observation and Their Deformation-induced Emission Characteristics.

Distinguishing the luminescence contribution from the surface and bulk of a crystal is a long-standing challenge in crystal materials. Herein, three-dimensional, multiphoton, luminescence microscope imaging of the elastic molecular single crystal 1,4-bis(4-methylthien-2-yl)-2,3,5,6-tetrafluorobenzene, was conducted. Further, the luminescence contribution from the surface and bulk of the crystal was experimentally distinguished. Strong luminescence was observed only from the surface of the crystal, while the bulk did not emit strongly. Furthermore, the surface and bulk luminescence behavior responded well to the mechanical shape change of the crystal; i.e., strong luminescence was observed for the elongated side of the crystal.

Formation of a Giant Anisotropically Ordered Assembled Structure of Inorganic Nanosheets through an Optically Induced Stream.

Formation of a desirable submillimeter-scaled assembled structure of particles in the colloid is a difficult subject in colloidal chemistry. Herein, a submillimeter-scaled ordered assembled structure consisting of highly anisotropic two-dimensional plate-like particles, niobate nanosheets, was obtained through an optical manipulation technique that was assisted by a scattering-force-induced stream. A 532 nm continuous wave laser beam with a power of 400 mW was used to illuminate a liquid crystalline niobate nanosheet colloid from the bottom side of a sample cell, inducing the stream of oriented nanosheets toward the upper side of the sample cell. As a result, a 200 µm ordered assembled structure consisting of oriented nanosheets was formed. The assembled structure was also characterized by two-dimensional anisotropy, reflecting that the highly anisotropic morphologies of each nanosheet and the shape of that structure were dependent on the polarization of incident illumination. This study has revealed a new noncontact and on-demand way to obtain submillimeter-scaled ordered anisotropic colloidal assembled structures of nanosized particles such as nanosheets, contributing to fundamental materials science and expanding the utilities of nanosheets.

Food appearance affects reward-related brain activity in healthy adults: a functional magnetic resonance imaging study.

A good appearance of food increases appetite. A new food product called iEat® resembles the appearance and softness of familiar foods. Previous studies have reported that iEat® foods increase appetite. However, the neuronal substrates underlying the increase in appetite following the observation of iEat® foods remain unknown. In the present study, the brain activity of 20 healthy adults during the visual presentation of iEat® and pureed foods and non-food objects was examined using functional magnetic resonance imaging. Compared with pureed foods and non-food objects, iEat® foods showed significantly greater activation in regions of the brain reward system, such as the amygdala, ventral striatum and orbital frontal cortex. In addition, individual differences in the activity of the left amygdala were positively correlated with subjective appetite ratings. These results suggest that the good appearance of foods, such as iEat® foods, may be useful for stimulating the appetite of patients with poor appetite.

Systematic Control of Structural and Photophysical Properties of π-Extended Mono- and Bis-BODIPY Derivatives.

A series of π-extended mono- and bis-BODIPY (BODIPY=boron-dipyrromethene) derivatives, namely, benzo[a]phenanthrene-fused BODIPY (Phena-Mono-BDP), benzo[a]anthracene-fused BODIPY (Ant-Mono-BDP), and dibenz[a,h]anthracene (DBA)-bridged bis-BODIPY (Ant-Bis-BDP), were designed and synthesized to examine their structural, electrochemical, and photophysical properties. Single-crystal X-ray crystallographic analyses demonstrated the planar configuration of Ant-Mono-BDP, in contrast to that of nonplanar Phena-Mono-BDP, whereas Ant-Bis-BDP has a DBA-centered planar configuration and two terminal nonplanar units of BODIPYs. The oxidation and reduction potentials agree with the estimated energies obtained through DFT calculations. The localized HOMO and LUMO states suggested the intramolecular charge-transfer characteristics in these BODIPY derivatives. The absorption spectra of these compounds extended up to the near-IR region. Strong redshifted trends of fluorescence spectra were observed in Ant-Bis-BDP with increasing solvent polarity, as supported by the differences in dipole moments estimated from Lippert-Mataga plots. To evaluate the excited-state dynamics of these molecules, the fluorescence quantum yield (ΦFL ) of Ant-Bis-BDP dramatically increased in the range from 0.05 to 0.86, with decreasing solvent polarity. Finally, the efficient two-photon absorption cross section of Ant-Bis-BDP (ca. 1200 GM at λ=1000 nm) was also obtained by considering the large π-extended structure (acceptor-donor-acceptor type).

Microscope Observation of Morphology of Colloidally Dispersed Niobate Nanosheets Combined with Optical Trapping.

Although inorganic nanosheets prepared by exfoliation (delamination) of layered crystals have attracted great attention as 2D nanoparticles, in situ real space observations of exfoliated nanosheets in the colloidally dispersed state have not been conducted. In the present study, colloidally dispersed inorganic nanosheets prepared by exfoliation of layered niobate are directly observed with bright-field optical microscopy, which detects large nanosheets with lateral length larger than several micrometers. The observed nanosheets are not strictly flat but rounded, undulated, or folded in many cases. Optical trapping of nanosheets by laser radiation pressure has clarified their uneven cross-sectional shapes. Their morphology is retained under the relation between Brownian motion and optical trapping.

Ferroelectric Behavior of a Hexamethylenetetramine-Based Molecular Perovskite Structure.

We report the development of a molecular ferroelectric material inspired by the hexamethylenetetramine (hmta) non-centrosymmetric molecular rotator. The bromide salt of diprotonated hmta (hmtaH2 ) crystalized as (hmtaH2 )(NH4 )Br3 in a metal-free ABX3 perovskite-type structure, in which the A and B sites are occupied by hmtaH2 2+ and ammonium cations, respectively. The compound crystallized in the Pma2 polar space group. A distorted polar perovskite structure formed owing to the distortion of {(NH4 )Br6 } octahedrons that are stabilized through the formation of NH⋅⋅⋅Br hydrogen bonds and the orientational ordering of positive charges on the non-centrosymmetric hmtaH2 molecules. This spontaneous polarization exhibited ferroelectric behavior with a nominally high Curie temperature (>400 K), in which the electrical switching of polarization originates from the rotation of the hmtaH2 unit.

The emergent intramolecular hydrogen bonding effect on the electronic structures of organic electron acceptors.

A new strategy for controlling the electron-accepting ability of an anthraquinone (AQ)-based π-molecular system is proposed to take advantage of intramolecular hydrogen bonding interactions. The electron-accepting properties of AQ are enhanced by the introduction of bulky arylsulfonamide groups into AQ derivatives due to the formation of effective intramolecular N-HO hydrogen bonding interaction and stabilization of the anion radical state even in solution.

A biphenyl type two-photon fluorescence probe for monitoring the mitochondrial membrane potential.

Here we describe the design and synthesis of a bifunctional two-photon fluorescence probe, N,N'-|dimethyl-4,4'-(biphenyl-2,1-ethenediyl)dipyridinium hexafluorophosphate (BP6). HeLa, Hek293, and Paramecium caudatum cells were stained with BP6. BP6 accumulated on the mitochondria of all three cell types when the mitochondrial membrane potential was high. As the mitochondrial membrane potential decreased following the addition of carbonyl cyanide m-chlorophenyl hydrazine, BP6 moved from the mitochondria to the nucleus in a reversible manner, depending on the mitochondrial membrane potential status. The maximum value of the two-photon absorption cross-section of BP6 is 250 GM (1 GM=1×10(-50) cm(4) s molecules(-1) photon(-1)). This value is 3 and 30 times larger, respectively, than that of the conventional mitochondria selective probes, rhodamine 123 and green fluorescence protein. These results suggest that BP6 should be useful for monitoring mitochondrial membrane potential by two-photon excitation.

Dynamic behavior, electrochromism, and two-photon absorption of dicyanomethylenated quinacridone.

Molecular structures of dicyanomethylenated quinacridone (1) as a solid and in solution were examined on the basis of single-crystal X-ray structural analysis, temperature-dependent (1)H NMR in CD2Cl2, and theoretical calculations. Crystal 1 had a curved, butterfly-shaped molecular structure. Thermally activated flipping between the curved, butterfly-shaped structure and an armchair structure occurred in solution. Electrochemical reduction triggered a dynamic change from the curved, butterfly-shaped conformation in the neutral state to a planar conformation in the dianion state, which represented electrochromic behavior with electrochemical bistability. A large two-photon absorption cross section of compound 1 was observed in the resonance-enhancement region of 423 GM (1 GM = 1 × 10(-50) cm(4) s photon(-1) molecule(-1)) at 710 nm. Multiple donor-acceptor charge-transfer pathways of molecule 1 enhanced two-photon absorption.

Subarachnoid hemorrhage secondary to a ruptured middle cerebral aneurysm in a patient with osteogenesis imperfecta: a case report.

BACKGROUND: Osteogenesis imperfecta (OI) is a heterogeneous group of inherited disorders that occur owing to the abnormalities in type 1 collagen, and is characterized by increased bone fragility and other extraskeletal manifestations. We report the case of a patient who was diagnosed with OI following subarachnoid hemorrhage (SAH) secondary to a ruptured saccular intracranial aneurysm (IA). CASE PRESENTATION: A 37-year-old woman was referred to our hospital because of sudden headache and vomiting. She was diagnosed with SAH (World Federation of Neurosurgical Society grade 2) owing to an aneurysm of the middle cerebral artery. She then underwent surgical clipping of the aneurysm successfully. She had blue sclerae, a history of several fractures of the extremities, and a family history of bone fragility and blue sclerae in her son. According to these findings, she was diagnosed with OI type 1. We performed genetic analysis for a single nucleotide G/C polymorphism (SNP) of exon 28 of the gene encoding for alpha-2 polypeptide of collagen 1, which is a potential risk factor for IA. However, this SNP was not detected in this patient or in five normal control subjects. Other genetic analyses did not reveal any mutations of the COL1A1 or COL1A2 gene. The cerebrovascular system is less frequently involved in OI. OI is associated with increased vascular weakness owing to collagen deficiency in and around the blood vessels. SAH secondary to a ruptured IA with OI has been reported in only six cases. CONCLUSION: The patient followed a good clinical course after surgery. It remains controversial whether IAs are caused by OI or IAs are coincidentally complicated with OI.

The size control of nano-cluster formed on an inorganic nanosheet/cationic organic molecule hybrid Langmuir-Blodgett film.

Organic molecules adsorbed on an inorganic nanosheet often form a nanometer-sized cluster. In this study, we propose novel strategy for controlling the cluster size. We fabricated hybrid Langmuir-Blodgett (LB) films consisting of N-n-octadecyl-4-[2-(4-dimethylaminophenyl)ethenyl]-pyridinium bromide and a clay mineral, sodium montmorillonite, with varying subphase temperature. As a result, the size of the clusters was found to be decreased from 300 nm to 50 nm by increasing the subphase temperature from 10 degrees C to 40 degrees C.

Beneficial effect of selective intra-arterial infusion of fasudil hydrochloride as a treatment of symptomatic vasospasm following SAH.

INTRODUCTION: We envisage the efficacy and safety of intra-arterial infusion of fasudil hydrochloride (IAF) for symptomatic vasospasm (SVS) after subarachnoid hemorrhage (SAH). We compared results obtained from the groups that received selective IAF (a microcatheter inserted in intracranial arteries) and nonselective IAF (a microcatheter inserted in the cervical arteries). Glasgow Outcome Scale (GOS) value and computed tomographic (CT) score were used to evaluate clinical outcome and the extent of infarction due to delayed vasospasm. MATERIAL AND METHODS: Over 2 years, 113 patients with SAH underwent clipping or coiling. Among them, 31 patients (27.4%) developed SVS. We performed nonselective IAF in 10 patients and selective IAF in 10 other patients. Eleven patients with SVS were treated without IAF. The data were statistically analyzed. RESULT: By univariate linear regression analysis, IAF negatively correlated with CT score (p = 0.016), but IAF was significantly correlated with GOS (p = 0.035). By multiple regression analysis, Hunt and Kosnik grade and CT score significantly correlated with GOS. DISCUSSION: CT score significantly correlated with functional outcome. Although IAF, both selective and nonselective, was significantly effective for the treatment of delayed vasospasm, the former seemed to be more beneficial.

NIR-II-Excitable Dye-Loaded Nanoemulsions for Two-Photon Microscopy Imaging of Capillary Blood Vessels in the Entire Hippocampal CA1 Region of Living Mice.

For in vivo two-photon fluorescence microscopy (2PM) imaging, the development of techniques that can improve the observable depth and temporal resolution is an important challenge to address biological and biomedical concerns such as vascular dynamics in the deep brain (typically the hippocampal region) of living animals. Improvements have been achieved through two approaches: an optical approach using a highly tissue-penetrating excitation laser oscillating in the second near-infrared wavelength region (NIR-II, 1100-1350 nm) and a chemical approach employing fluorescent probes with high two-photon brightness (characterized by the product of the two-photon absorption cross section, σ2, and the fluorescence quantum yield, Φ). To integrate these two approaches, we developed a fluorescent dye exhibiting a sufficiently high σ2Φ value of 68 Goeppert-Mayer units at 1100 nm. When a nanoemulsion encapsulating >1000 dye molecules per particle and a 1100 nm laser were employed for 2PM imaging, capillary blood vessels in almost the entire hippocampal CA1 region of the mouse brain (approximately 1.1-1.5 mm below the surface) were clearly visualized at a frame rate of 30 frames s-1 (averaged over eight frames, practically 3.75 frames s-1). This observable depth and frame rate are much higher than those in previous reports on 2PM imaging. Furthermore, this nanoemulsion allowed for the visualization of blood vessels at a depth of 1.8 mm, corresponding to the hippocampal dentate gyrus. These results highlight the advantage of combining bright probes with NIR-II lasers. Our probe is a promising tool for studying the vascular dynamics of living animals and related diseases.

High-throughput walkthrough detection portal for counter terrorism: detection of triacetone triperoxide (TATP) vapor by atmospheric-pressure chemical ionization ion trap mass spectrometry.

With the aim of improving security, a high-throughput portal system for detecting triacetone triperoxide (TATP) vapor emitted from passengers and luggage was developed. The portal system consists of a push-pull air sampler, an atmospheric-pressure chemical ionization (APCI) ion source, and an explosives detector based on mass spectrometry. To improve the sensitivity of the explosives detector, a novel linear ion trap mass spectrometer with wire electrodes (wire-LIT) is installed in the portal system. TATP signals were clearly obtained 2 s after the subject under detection passed through the portal system. Preliminary results on sensitivity and throughput show that the portal system is a useful tool for preventing the use of TATP-based improvised explosive devices by screening persons in places where many people are coming and going.

Ferroelectric columnar assemblies from the bowl-to-bowl inversion of aromatic cores.

Organic ferroelectrics, in which the constituent molecules retain remanent polarization, represent an important topic in condensed-matter science, and their attractive properties, which include lightness, flexibility, and non-toxicity, are of potential use in state-of-the-art ferroelectric devices. However, the mechanisms for the generation of ferroelectricity in such organic compounds remain limited to a few representative concepts, which has hitherto severely hampered progress in this area. Here, we demonstrate that a bowl-to-bowl inversion of a relatively small organic molecule with a bowl-shaped π-aromatic core generates ferroelectric dipole relaxation. The present results thus reveal an unprecedented concept to produce ferroelectricity in small organic molecules, which can be expected to strongly impact materials science.

Enhanced photodegradation of organic dyes adsorbed on a clay.

The interaction of three photoactive organic dyes, Rhodamine B, Rhodamine 6G and a stilbazolium derivative 4'-dimethylamino-N-methyl-4-stilbazolium with synthetic sodium-saponite has been examined by UV-visible absorption spectroscopy. In all cases, bathochromic shifts and the reduction of peak absorbance for the dyes were observed in the absorption spectra at a low dye concentration (25% adsorption of the cation exchange capacity (CEC) of the clay), although the shape and the width of their absorption bands were similar to those in aqueous solution. This absorption behavior indicates that the organic dye molecules adsorbed onto the surface of the negatively charged clay particles and the adsorbed molecules were well dispersed. The photodegradation of the organic dyes in aqueous solution and in the clay suspension has been also examined by the irradiation of a laser beam at a wavelength of 532 nm. We have found that the hybridization of the organic dyes with the exfoliated clay particles largely enhanced a photodegradation. The clay particles acted as a catalyst even at a high concentration such as approximately 300% of CEC.

Two-photon absorption properties of azulenyl compounds having a conjugated ketone backbone.

Two-photon absorption (TPA) properties of newly synthesized conjugated ketone derivatives that include nonalternant azulenyl moieties in the pi-conjugation system, alpha,alpha'-bis(1-azulenylidene)cyclopentanone (1Az), alpha,alpha'-bis(2-azulenylidene)cyclopentanone (2Az), and alpha,alpha'-bis(6-azulenylidene)cyclopentanone (6Az) are reported. TPA spectra of these azulenyl compounds were measured using the open-aperture Z-scan method with a femtosecond laser. The TPA cross section at the peak position (sigma(2)peak) of 1Az was found to be the largest among the three azulenyl compounds, which is almost 7 times larger than that of the alpha,alpha'-bis(1-naphthylidene)cyclopentanone (1Nph), an alternant isomer of 1Az with the same number of pi-electrons. The small detuning energies of the azulenyl compounds compared to those of 1Nph were responsible for the large TPA cross sections. We report that a compound having an azulenyl moiety can be a promising TPA material.

Bright and two-photon active red fluorescent dyes that selectively move back and forth between the mitochondria and nucleus upon changing the mitochondrial membrane potential.

Since mitochondrial dysfunction was discovered to be the underlying cause of several severe diseases, fluorescent probes with excellent optical properties for visualising and monitoring the mitochondrial membrane potential (MMP) (a parameter of mitochondrial vitality) have been in high demand. Herein, we present novel pyrene-based dyes exhibiting remarkably large two-photon absorption around 900 nm and bright red emission around 620 nm (two-photon brightness (Φσ2) = 425-525 GM), with selective localisation to the mitochondria or nucleus in response to changes in the MMP, providing several advantages over traditional MMP-monitoring probes such as Rhodamine 123 (Φσ2 = 64 GM). The intracellular behavior of the new dyes was investigated in detail. The driving forces for the dyes to dissociate from the mitochondria and migrate toward the nucleus upon decreasing the MMP were two key molecular characteristics: the dyes' permeability to mitochondrial membranes and their affinity to nuclear DNA. The results provide significant insights into improving the molecular design of the dyes.

Tunable High-Pressure Field Operating on a Cationic Biphenyl Derivative Intercalated in Clay Minerals.

We propose a methodology for applying a pseudo uniaxial pressure to an organic molecule under ordinary temperature and pressure, namely by intercalation into smectites. The pseudo pressure on a biphenyl derivative (BP) was estimated from the averaged dihedral angle around the central bond of BP. In a high hydrostatic pressure field, biphenyl takes a planar conformation. In the interlayer space of synthetic saponite (SSA), the averaged dihedral angle of BP at a loading level of 27% versus the cation exchange capacity was ~26.3°, which indicates that the pseudo pressure applied to BP in the SSA interlayer space corresponds to 0.99 GPa. The high pseudo-pressure field in the interlayer space of SSA was also confirmed by absorption measurements. The dihedral angle around the central bond of the biphenyl moiety decreased to enhance the planarity of the molecule, mainly in response to the electrostatic force that operates between the negatively charged SSA layer and the interlayer cation. The pseudo pressure operating on BP in the smectite interlayer space could be controlled by varying the smectite layer charge density and/or the BP loading level. By using this methodology, controllable pseudo high-pressure properties of organic molecules can be obtained at ordinary temperatures and pressures.