Novel Expansion/shrinkage Modulation of 2D Layered MOF Triggered by Clathrate Formation with CO(2) Molecules

Nano Letters. Nov, 2006  |  Pubmed ID: 17090095

Crystal-to-crystal transformation from a 3D interpenetrated-type MOF {[Cu(BF(4))(2)(bpy)(H(2)O)(2)] (bpy)} (1) to a 2D square-grid-type [Cu(BF(4))(2)(bpy)(2)] (2) (bpy = 4,4'-bipyridine) was observed. It was derived from dehydration and confirmed by in situ FT-IR, TG, and elemental analysis. Moreover, we elucidate the novel expansion/shrinkage dynamic modulation of 2 triggered by clathrate formation with gas molecules.

Coordination Symmetry-dependent Structure Restoration Function of One-dimensional MOFs by Molecular Respiration

The Journal of Physical Chemistry. B. Dec, 2006  |  Pubmed ID: 17181185

One-dimensional metal-organic compounds with cis, trans symmetry-controlled counter anions were synthesized (cis compound {[Cu(azpy)(H2O)2(OTs)2]*2H2O*(acetone)} (1) and trans compound {[Cu(H2O)4Cu(azpy)2(OTs)2(H2O)2]*2(OTs)*2H2O*2EtOH} (2)). Only 2, having trans conformation, exhibited a complete structure-restoration effect with a mechanism involving layering of molecular "bricks" of water and solvent molecules.

Adsorption of Water on Three-dimensional Pillared-layer Metal Organic Frameworks

Journal of Colloid and Interface Science. Oct, 2007  |  Pubmed ID: 17632118

We showed water adsorption isotherms at 303 K on water-resistant three-dimensional (3-D) pillared-layer metal organic frameworks (MOFs) with 1-D semi-rectangular pores, of which size depends on the length of ligand. The shapes of all three adsorption isotherms are type I by IUPAC classification showing strong water-MOFs interaction. The adsorbed amount of water molecules on the hydrophilic site of carboxylic group in 2-D sheets coincided with the crystal water amount. The adsorption on the hydrophilic sites occurs at similar relative pressure even if the used ligand is different.

Double-step Gas Sorption of a Two-dimensional Metal-organic Framework

Journal of the American Chemical Society. Oct, 2007  |  Pubmed ID: 17887754

Coordinated NH3-removal-induced Hydrogen Adsorption of Cu-complex Crystals

Langmuir : the ACS Journal of Surfaces and Colloids. Jan, 2008  |  Pubmed ID: 18047377

We synthesized a discrete type of organic-inorganic hybrid crystal [Cu(ina)2(NH3)2(H2O)2] (ina = isonicotinate). The monomer units connect to each other with hydrogen bonds and pi-pi interactions, forming a three-dimensional network. Removal of ammonia and water molecules by vacuum heating treatment induced a substantial change from nonporous to porous crystals. The resultant porous crystals can predominantly adsorb supercritical hydrogen rather than nitrogen vapor at 77 K.

Quantum Sieving Effect of Three-dimensional Cu-based Organic Framework for H2 and D2

Journal of the American Chemical Society. May, 2008  |  Pubmed ID: 18444644

The crystal structure of [Cu(4,4'-bipyridine) 2(CF 3SO 3) 2] n metal-organic framework (CuBOTf) of one-dimensional pore networks after pre-evacuation at 383 K was determined with synchrotron X-ray powder diffraction measurement. Effective nanoporosity of the pre-evacuated CuBOTf was determined with N 2 adsorption at 77 K. The experimental H 2 and D 2 adsorption isotherms of CuBOTf at 40 and 77 K were measured and then compared with GCMC-simulated isotherms using the effective nanoporosity. The quantum-simulated H 2 and D 2 isotherms at 77 K using the Feynman-Hibbs effective potential coincided with the experimental ones, giving a direct evidence on the quantum molecular sieving effect for adsorption of H 2 and D 2 on CuBOTf. However, the selectivity for the 1:1 mixed gas of H 2 and D 2 was 1.2. On the contrary, experimental H 2 and D 2 isotherms at 40 K had an explicit adsorption hysteresis, originating from the marked pore blocking effect on measuring the adsorption branch. The blocking effect for quantum H 2 is more prominent than that for quantum D 2; the selectivity for D 2 over H 2 at 40 K was in the range of 2.6 to 5.8. The possibility of the quantum molecular sieving effect for H 2 and D 2 adsorption on [Cu 3(benzene-1,3,5-tricarboxylate) 2(H 2O) 3] n of three-dimensional pore networks was also shown at 77 K.

Graded-index Plastic Optical Fiber Prepared by the Coextrusion Process

Applied Optics. Aug, 2008  |  Pubmed ID: 18670576

A graded-index plastic optical fiber (GI POF) has been proposed as the transmission medium to realize high-speed information transmission. We have succeeded in fabricating a GI POF by the dopant diffusion coextrusion process, a method that allows continuous fabrication of GI POF. Although it has been indicated that the refractive index distribution of GI POF fabricated by this process is formed by Fick diffusion with the diffusion coefficient dependent on dopant concentration, the method to control it remains unknown. The purposes of this study are to establish the technology of stable fabricating of GI POF by the coextrusion process and to analyze the bandwidth.

Functional Analysis of C2H2 Zinc Finger Transcription Factor CrzA Involved in Calcium Signaling in Aspergillus Nidulans

Current Genetics. Dec, 2008  |  Pubmed ID: 19002465

Calcium signaling systems are widely employed in eukaryotes and are implicated in the regulation of diverse biological processes. Calcineurin is an important signaling component, which mediates ion homeostasis and virulence in several fungi. Based on intensive studies conducted on budding yeast, transcription factor Crz1p is thought to be a target of calcineurin. To provide insight into calcium signaling, a Crz1p homolog (CrzA) in a filamentous fungus Aspergillus nidulans was identified and its function with special reference to calcium response was characterized. A crzA gene disruption mutant exhibited sensitivity to high concentrations of Mn(2+) and Ca(2+), and mediated the expression of P-type calcium-ATPase homologous genes. Comprehensive transcriptional analysis with DNA microarrays indicated that CrzA regulates the expression of a vacuolar Ca(2+)/H(+) exchanger gene in response to external calcium stimuli. It is suggested that the calcineurin-CrzA pathway is the mediator of Ca(2+) homeostasis in A. nidulans. Moreover, a crzA/hogA double mutant showed hypersensitivity to osmotic stress, indicating the importance of calcium homeostasis for adaptation to osmotic stress, a universal stress in filamentous fungi.

Reversible Structural Change of Cu-MOF on Exposure to Water and Its CO2 Adsorptivity

Langmuir : the ACS Journal of Surfaces and Colloids. Apr, 2009  |  Pubmed ID: 19271756

It is important to study the interaction between water molecules and a host structure for understanding the adsorption mechanism of metal-organic framework (MOF) materials. The evolution of the structure of a flexible Cu-MOF, {[Cu(bpy)(H2O)2(BF4)2](bpy)} (bpy=4,4'-bipyridine), upon dehydration and rehydration was studied by thermogravimetric analysis (TGA), infrared (IR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and water adsorption. A nearly reversible structural change was observed upon rehydration. More importantly, a unique CO2 "gate adsorption" phenomenon was observed despite the exposure of the Cu-MOF to water. This shows that the Cu-MOF has relatively good stability after exposure to water.

Elastic Layer-structured Metal Organic Frameworks (ELMs)

Journal of Colloid and Interface Science. Jun, 2009  |  Pubmed ID: 19383559

Elastic layer-structured metal organic frameworks (ELMs) having flexible two-dimensional structure show a gate phenomenon in sorption/desorption of simple gas molecules. The gate phenomenon is accompanied by expansion/shrinkage of the layers. The gas sorption/desorption is not based on a physical adsorption, but on a chemical reaction, which includes high cooperativity. The cooperative reaction could be analyzed thermodynamically. The gate phenomenon showed advantages in separation of CO2 from mixed gases and in storage of CH4 owing to easy release of absorbed molecules.

Metal-ion-dependent Gas Sorptivity of Elastic Layer-structured MOFs

Chemistry (Weinheim an Der Bergstrasse, Germany). Aug, 2009  |  Pubmed ID: 19569143

A Case of Reversible Hyposmia Associated with Mikulicz's Disease

Otolaryngology--head and Neck Surgery : Official Journal of American Academy of Otolaryngology-Head and Neck Surgery. Sep, 2009  |  Pubmed ID: 19716031

Innovative Radiographic System to Improve the Sharpness of Radiographs: Could a Phase-shift Effect Contribute to Improved Image-quality for Plain Computed Radiographs for General Use?

Japanese Journal of Radiology. Jan, 2010  |  Pubmed ID: 20112099

The aim of this study was to determine whether a high-resolution digital radiography system that was originally developed for mammography could be used for general radiographic purposes by means of a phantom test.

Changes in Cerebral Perfusion in Extremely LBW Infants During the First 72 H After Birth

Pediatric Research. Nov, 2010  |  Pubmed ID: 20657347

Cerebral perfusion and its relation with systemic circulation in extremely LBW (ELBW) infants in the early neonatal period are not well understood. The cerebral tissue oxygenation index (TOI) and cerebral fractional tissue oxygen extraction (FTOE) were monitored in stable 16 ELBW infants (GA <29 wk) using near-infrared spectroscopy (NIRS) at 3-6, 12, 18, 24, 36, 48, and 72 h after birth. The left ventricular end-systolic wall stress (ESWS), left ventricular ejection fraction (LVEF), left ventricular cardiac output (LVCO), and superior vena cava (SVC) flow were also measured simultaneously using echocardiography. The ESWS increased till 18 h and then decreased; LVEF, LVCO, and SVC flow decreased till 12 h and increased thereafter. The TOI decreased till 12 h and correlated with SVC flow; FTOE increased until 12 h and then decreased. These changes in variables of NIRS and echocardiographic measurements contrasted to changes in mean arterial blood pressure (MABP), which showed trends of continuous and gradual increase after birth. We conclude that even stable ELBW infants undergo evident transitional changes in cerebral oxygenation and perfusion in the early postnatal period, which may reflect changes in cardiac function and cardiac output.

Dynamic Changes in Dimensional Structures of Co-complex Crystals

Inorganic Chemistry. Oct, 2010  |  Pubmed ID: 20843060

A two-dimensional flexible porous coordination polymer (2D-PCP) that shows expansion/shrinkage structural transformation accompanied by molecular accommodation was synthesized by control of dimensionality in zero-dimensional and one-dimensional PCPs: The dynamic structural transformation cooperatively proceeds in the solid state with a drastic molecular rearrangement. Kinetics of the structural transformation was investigated.

Flexible Two-dimensional Square-grid Coordination Polymers: Structures and Functions

International Journal of Molecular Sciences. 2010  |  Pubmed ID: 21152303

Coordination polymers (CPs) or metal-organic frameworks (MOFs) have attracted considerable attention because of the tunable diversity of structures and functions. A 4,4'-bipyridine molecule, which is a simple, linear, exobidentate, and rigid ligand molecule, can construct two-dimensional (2D) square grid type CPs. Only the 2D-CPs with appropriate metal cations and counter anions exhibit flexibility and adsorb gas with a gate mechanism and these 2D-CPs are called elastic layer-structured metal-organic frameworks (ELMs). Such a unique property can make it possible to overcome the dilemma of strong adsorption and easy desorption, which is one of the ideal properties for practical adsorbents.

Successive Iterative Restoration Applied to Streak Artifact Reduction in X-ray CT Image of Dento-alveolar Region

International Journal of Computer Assisted Radiology and Surgery. Sep, 2011  |  Pubmed ID: 21207177

X-ray computed tomography (CT) images in the dento-alveolar region are sometimes rendered unusable for diagnostic purposes due to the appearance of streak artifacts. The purpose of the study is to reduce streak artifacts appeared on dental and maxillofacial X-ray CT images by the application of modified iterative restoration method.

A Clinical Study of Olfactory Dysfunction in Patients with Mikulicz's Disease

Auris, Nasus, Larynx. Jun, 2011  |  Pubmed ID: 21216547

Mikulicz's disease (MD) is differentiated from Sjögren's syndrome as an immunoglobulin G4 (IgG4) systemic disease. MD patients often report olfactory dysfunction (OD). To analyze cases of OD associated with MD, we studied clinicopathological and serological findings of MD patients.

Tuning of Gate Opening of an Elastic Layered Structure MOF in CO2 Sorption with a Trace of Alcohol Molecules

Langmuir : the ACS Journal of Surfaces and Colloids. Jun, 2011  |  Pubmed ID: 21534550

It is important to tune the sorption behavior of metal-organic framework (MOF) materials. Ethanol treatment on the hydrated form of [Cu(bpy)(2)(BF(4))(2)], which is a representative flexible MOF showing the fascinating gate phenomenon on CO(2) sorption, induces an easier dehydration and a significant decrease in the CO(2) gate pressure. The results of IR, X-ray diffraction (XRD), and X-ray absorption fine structure (XAFS) measurements indicated that water molecules in the lattice of the hydrated form can be removed even at room temperature after the ethanol treatment and the basic 2D layered structure remains with a slight interlayer expansion. The results of thermogravimetric (TG) and gas chromatograph/mass spectrometry (GC/MS) analyses and of CO(2) sorptions indicated that the change of the gate phenomenon was caused by a trace of residual ethanol molecules included in the structure. Similar phenomena were observed on alcohols with different polarity and molecular size.

Super Flexibility of a 2D Cu-based Porous Coordination Framework on Gas Adsorption in Comparison with a 3D Framework of Identical Composition: Framework Dimensionality-dependent Gas Adsorptivities

Journal of the American Chemical Society. Jul, 2011  |  Pubmed ID: 21671624

Selective synthetic routes to coordination polymers [Cu(bpy)(2)(OTf)(2)](n) (bpy = 4,4'-bipyridine, OTf = trifluoromethanesulfonate) with 2- and 3-dimensionalities of the frameworks were established by properly choosing each different solvent-solution system. They show a quite similar local coordination environment around the Cu(II) centers, but these assemble in a different way leading to the 2D and 3D building-up structures. Although the two kinds of porous coordination polymers (PCPs) both have flexible frameworks, the 2D shows more marked flexibility than the 3D, giving rise to different flexibility-associated gas adsorption behaviors. All adsorption isotherms for N(2), CO(2), and Ar on the 3D PCP are of type I, whereas the 2D PCP has stepwise gas adsorption isotherms, also for CH(4) and water, in addition to these gases. The 3D structure, having hydrophilic and hydrophobic pores, shows the size-selective and quadrupole-surface electrical field interaction dependent adsorption. Remarkably, the 2D structure can accommodate greater amounts of gas molecules than that corresponding to the inherent crystallographic void volume through framework structural changes. In alcohol adsorption isotherms, however, the 2D PCP changes its framework structure through the guest accommodation, leading to no stepwise adsorption isotherms. The structural diversity of the 2D PCP stems from the breathing phenomenon and expansion/shrinkage modulation.

Mucosal Immune Barrier and Antigen-presenting System in Human Nasal Epithelial Cells

Advances in Oto-rhino-laryngology. 2011  |  Pubmed ID: 21865683

The upper respiratory tract including the nasal cavity, which is the first site of invading antigen exposure, plays a crucial role in host defense via the mucosal immune response. The epithelium of nasal mucosa forms a continuous barrier against a wide variety of exogenous antigens. The epithelial barrier function is regulated in large part by the apical-most intercellular junction, referred to as the tight junction. Antigen-presenting cells, particularly dendritic cells (DCs), are known to play an important role in human nasal mucosa. Recently, the author and colleagues discovered a new mechanism for pathogen uptake in the nasal mucosa, by which DCs open the tight junctions between epithelial cells and send dendrites outside the epithelium to directly sample the pathogen. In order to preserve the integrity of the epithelial barrier and penetrate beyond well-developed epithelial tight junctions, DCs express tight junction proteins. We also found that these DCs are activated by nasal epithelial-derived TSLP induced by stimuli such as cytokines and Toll-like receptor ligands. In this lecture, I will talk about the novel mechanisms in host defense in terms of innate immunity of the nasal mucosa from the point of view of the mucosal barrier function.

Spontaneous Regression of Lung Lesions After Excision of the Submandibular Gland in a Patient with Chronic Sclerosing Sialadenitis

Auris, Nasus, Larynx. Apr, 2012  |  Pubmed ID: 21571470

Chronic sclerosing sialadenitis, which clinically resembles a salivary gland tumor, is considered a salivary gland lesion of the IgG4-related inflammatory disease. Corticosteroids are effective for the treatment of chronic sclerosing sialadenitis, but the natural clinical course of this disease is not fully understood. We report a 67-year-old man with chronic sclerosing sialadenitis who showed lung lesions, which spontaneously regressed without steroid therapy after excision of the submandibular gland. He presented with several weeks' history of continuous swelling in the right submandibular region. Physical examination showed a hard swelling of the right submandibular gland; the cytological finding was Papanicolaou class III. A chest X-ray demonstrated bilateral infiltration of the right middle and left lower lobes. The right submandibular gland was excised under general anesthesia for definite diagnosis, and histopathological examination revealed an IgG4-positive plasmacytic infiltration accompanied by periductal fibrosis and interlobular sclerosis, consistent with chronic sclerosing sialadenitis. Five months after operation, the lung lesions regressed spontaneously.