Precise control of quantum dot location within the P3HT-b-P2VP/QD nanowires formed by crystallization-driven 1D growth of hybrid dimeric seeds.

Herein, we report a simple fabrication of hybrid nanowires (NWs) composed of a p-type conjugated polymer (CP) and n-type inorganic quantum dots (QDs) by exploiting the crystallization-driven solution assembly of poly(3-hexylthiophene)-b-poly(2-vinylpyridine) (P3HT-b-P2VP) rod-coil amphiphiles. The visualization of the crystallization-driven growth evolution of hybrid NWs through systematic transmission electron microscopy experiments showed that discrete dimeric CdSe QDs bridged by P3HT-b-P2VP polymers were generated during the initial state of crystallization. These, in turn, assemble into elongated fibrils, forming the coaxial P3HT-b-P2VP/QDs hybrid NWs. In particular, the location of the QD arrays within the single strand of P3HT-b-P2VP can be controlled precisely by manipulating the regioregularity (RR) values of P3HT block and the relative lengths of P2VP block. The degree of coaxiality of the QD arrays was shown to depend on the coplanarity of the thiophene rings of P3HT block, which can be controlled by the RR value of P3HT block. In addition, the location of QDs could be regulated at the specific-local site of P3HT-b-P2VP NW according to the surface characteristics of QDs. As an example, the comparison of two different QDs coated with hydrophobic alkyl-terminated and hydroxyl-terminated molecules, respectively, is used to elucidate the effect of the surface properties of QDs on their nanolocation in the NW.

Expression, purification and characterization of human vacuolar-type H(+)-ATPase subunit d1 and d2 in Escherichia coli.

Vacuolar-type H(+)-ATPase (V-ATPase) is a multi-subunit proton pump. The proton pump is essential for the regulation of pH in various eukaryotic cellular processes. Among the 14 subunits that constitute V-ATPase, d subunit mediates coupling between cytosolic and membrane domains. Whereas d1 is expressed ubiquitously in various types of cells, its isoform d2 is only expressed in specific cells or tissues. To characterize these isoforms, we expressed and purified the isoforms of human V-ATPase d subunits using Escherichia coli over-expression system. Subunit d1 and d2 were purified as homogeneous monomers as demonstrated by dynamic light scattering (DLS) analysis. Secondary structures of d subunits were estimated to be composed of 73% α-helix and 2% ß-sheet, as analyzed using circular dichroism (CD) analysis. Although sequence identity and secondary structures of d subunits were highly similar, the relative stability against thermal stress was higher for d1 than d2. Efficient expression and purification of d subunits, together with biophysical and biochemical characterization, presented in this study is expected to facilitate further structural analysis to clarify specific inter-molecular interactions involved in multi-subunit assembly and regulation of H(+) transporters.

Cation disordering by rapid crystal growth in olivine-phosphate nanocrystals.

On the basis of Pauling's first rule for ionic bonding, the coordination number of cations with oxygen anions can be determined by comparison of their relative ionic size ratio. In contrast to simple oxides, various site occupancies by multicomponent cations with similar sizes usually occur in complex oxides, resulting in distinct physical properties. Through an unprecedented combination of in situ high-temperature high-resolution electron microscopy, crystallographic image processing, geometric phase analysis, and neutron powder diffraction, we directly demonstrate that while the initial crystallites after nucleation during crystallization have a very high degree of ordering, significant local cation disordering is induced by rapid crystal growth in Li-intercalation metal-phosphate nanocrystals. The findings in this study show that control of subsequent crystal growth during coarsening is of great importance to attain a high degree of cation ordering, emphasizing the significance of atomic-level visualization in real time.

Assessment of Morphologic Change of Mandibular Condyle in Temporomandibular Joint Osteoarthritis Patients with Stabilization Splint Therapy: A Pilot Study.

(1) Background: The purpose of this study was to evaluate the 3-dimensional bony changes of the mandibular condyle in temporomandibular joints-osteoarthritis (TMJ-OA) patients treated with stabilization splint (SS) therapy using shape correspondence analysis. (2) Methods: A total of 27 adult patients (2 men and 25 women) with a mean age of 24.6 ± 3.9 years were included in this study. All patients were diagnosed with TMJ-OA and were treated with an SS. Cone-beam computed tomography data of the condylar head before and after SS therapy from 42 condyles (15 bilateral and 12 unilateral TMJ-OA) were used for the analysis. For the performance shape correspondence analysis (SPHARM-PDM), statistical differences were performed using the one-way analysis of variance and Scheffe post hoc tests. (3) Results: After SS treatment in TMJ-OA patients, bone resorption of the condyle head surface was predominant in the anterosuperior, superolateral, and superior areas, and bone formation was superior in the lateral, medial, posterosuperior, and posteromedial areas. The change in the condylar volume between the two groups was not statistically significant. (4) Conclusions: After SS treatment in TMJ-OA patients, there was both bone resorption and bone formation on the mandibular condyle head surface, which induced morphological changes in the condyle head.

A long-term longitudinal study of the osteoarthritic changes to the temporomandibular joint evaluated using a novel three-dimensional superimposition method.

The aim of this study was to assess the changes in individual condyles from 5 to 8 years in patients with temporomandibular joint (TMJ) osteoarthritis using 3-dimensional cone beam computed tomography (3D CBCT) reconstruction and superimposition. To assess the longitudinal TMJ changes, CBCT was performed at initial (T0) and final (T2) timepoints that were at least 5 years apart and at a middle (T1) timepoint. To improve the accuracy, we used a novel superimposition method that designated areas of coronoid process and mandibular body. The differences in the resorption and apposition amounts were calculated between each model via maximum surface distances. The greatest resorption and apposition observed were - 7.48 and 2.66 mm, respectively. Evaluation of the changes in each condyle showed that osteoarthritis leads to both resorption and apposition. Resorption was mainly observed in the superior region, while high apposition rates were observed (in decreasing order) in the posterior, lateral, and anterior regions. The medial parts showed greater apposition than the lateral parts in all regions. Our superimposition method reveals that both resorption and apposition were observed in condyles with TMJ osteoarthritis, and resorption/apposition patterns depend on the individual condyle and its sites.

Structure analysis of inorganic crystals by energy-filtered precession electron diffraction.

We performed structure analysis of Si single crystal and CaMoO(4) inorganic crystal by energy-filtered precession electron diffraction (PED). Structure analysis was performed using conventional selected area electron diffraction, PED and energy-filtered PED (EF-PED). The EF-PED method proved to be advantageous in determining the crystal structures and accurate cell parameters of inorganic crystals due to resolution enhancement by sharpening the peak shapes and reducing inelastic scattering. Among the EF-PED methods, zero-loss PED was most useful for structure analysis by minimizing inelastic scattering intensities, while plasmon-loss PED could be used effectively to determine crystal symmetry by closely observing the conditions of forbidden reflections.

Growth of close-packed crystalline polypyrrole on graphene oxide via in situ polymerization of two-monomer-connected precursors.

Synthesis of a two-dimensional (2D) highly crystalline composite, P(Py:BPDSA:Py)-GO, from the growth of a close-packed polymer crystal, P(Py:BPDSA:Py), on graphene oxide (GO) sheets via in situ polymerization of two-monomer-connected precursors (TMCPs, Py:BPDSA:Py), in which two pyrrole (Py) molecules are linked through a connector (4,4'-biphenyldisulfonic acid) (BPDSA), is reported. When the TMCP is polymerized on GO, it leads to an exceptionally ordered structure determined by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) studies. X-ray crystallography of the composite shows crystalline peaks with d spacings in the [100] direction. Transmission electron microscopy (TEM) analysis indicates that the composite has a face-centered cubic (FCC) crystal structure. Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS) show that this composite with a well-defined nanostructure was successfully synthesized. Nitrogen adsorption-desorption isotherms show that this composite, P(Py:BPDSA:Py)-GO, has an improved specific surface area (71 m2 g-1) compared to that of P(Py:BPDSA:Py) (3.1 m2 g-1). The electrochemical properties of the composite studied by cyclic voltammetry indicates a specific capacitance of 480 F g-1 without an additional conducting material such as carbon black, suggesting its use as a pseudocapacitor.

In situ dynamic HR-TEM and EELS study on phase transitions of Ge2Sb2Te5 chalcogenides.

The phase transition phenomena of Ge2Sb2Te5 chalcogenides were investigated by in situ dynamic high-resolution transmission electron microscopy (HR-TEM) and electron energy loss spectroscopy (EELS). A 300kV field emission TEM and a 1250kV high voltage TEM were employed for the in situ heating experiments from 20 to 500 degrees C for undoped and 3wt% nitrogen-doped Ge2Sb2Te5 thin films deposited by DC sputtering. Crystallization of amorphous Ge2Sb2Te5 to its cubic structure phase started at 130 degrees C and then rapid crystal growth developed from cubic to hexagonal phase in the range of 130-350 degrees C; finally, the hexagonal crystals started to melt at 500 degrees C. For nitrogen-doped Ge2Sb2Te5, its crystallization from amorphous film occurred at higher temperature of ca. 200 degrees C, and the cubic and hexagonal phases were usually formed simultaneously without significant growth of crystals at further heating to 400 degrees C. EELS measurements showed that the electronic structures of Ge, Sb and Te stayed almost the same regardless of the amorphous, FCC and hexagonal phases. The nitrogen doped in Ge2Sb2Te5 was confirmed to exist as a nitride. Also, the doped nitrogen distributed homogeneously in both amorphous and crystalline phases. Localization of doped nitrogen was not found in the grain boundary of crystallized phases. The dynamic process of phase transition was enhanced by high-energy electron irradiation. Peeling of atomic layers in nitrogen-doped Ge2Sb2Te5 film was detected during heating assisted with electron beam irradiation.

Correction: Correlative microscopy of the constituents of a dinosaur rib fossil and hosting mudstone: Implications on diagenesis and fossil preservation.

[This corrects the article DOI: 10.1371/journal.pone.0186600.].

Quantitative evaluations of a high-voltage multiscan CCD camera.

Electron detection characteristics such as modulation transfer function (MTF), detection quantum efficiency (DQE), dynamic range, linearity, average gain, and uniformity of a high-voltage multiscan CCD (HV-MSC, 1K x 1K pixels) camera were evaluated. This camera was used as a major recording medium in a high-voltage electron microscope (HVEM) installed at the Korea Basic Science Institute (KBSI). In spite of the high energy of the incident electrons, the overall properties of the HV-MSC camera were comparable to other CCD cameras for a low-voltage electron microscope (LVEM). In order to take full advantages of the properties of the HV-MSC camera for atomic resolution electron microscopy, we discuss optimal experimental conditions based on the detection properties.

Immunohistochemical and electron microscopic study of the meridian-like system on the surface of internal organs of rats.

Threadlike structures on the surfaces of mammalian internal organs were recently observed, and they can be the anatomical basis of the meridian-like network of internal organs as detected by the Bi-Digital O-Ring test imaging method. Morphological and histological studies were performed to reveal their novel features by using confocal and electron microscopy, and there is evidence that reveals that they have a ductal structure in which some liquid flows. They form a part of the network of acupuncture meridians that is thought to be a circulatory system distributed throughout an animal body. In order to confirm further the circulatory function it was necessary to provide evidences for the existence of endothelial cells at the inner boundaries of the microchannels that form the threadlike ducts. In this work we performed immunohistochemical studies for the identification of endothelial cells. In addition, we identified the extracellular matrices between the microchannels in the threadlike structure by using antifibronectin, elastin, laminin, and collagen type IV. Since immunohistochemical data are not sufficient for definite proof we supplemented the analysis with ultra structural information by using transmission electron microscopy (TEM). Yet TEM images show only ultrathin sections (50 nm) of a specimen, we needed to take 3-dimentional images to provide a visual demonstration of the microchannels in the threadlike ducts. We conducted high voltage electron microscopic studies for this purpose and obtained corroborating tomograms that exhibit the microchannels. In conclusion, the meridian-like tissues are ducts with microchannels, which implies the circulatory function of the acupuncture meridian network.

Disparities in correlating microstructural to nanostructural preservation of dinosaur femoral bones.

Osteohistological researches on dinosaurs are well documented, but descriptions of direct correlations between the bone microstructure and corresponding nanostructure are currently lacking. By applying correlative microscopy, we aimed to verify that well-preserved osteohistological features correlate with pristine fossil bone nanostructures from the femoral bones of Koreanosaurus boseongensis. The quality of nanostructural preservation was evaluated based on the preferred orientation level of apatite crystals obtained from selected area electron diffraction (SAED) patterns and by measuring the "arcs" from the {100} and {002} diffraction rings. Unlike our expectations, our results revealed that well-preserved microstructures do not guarantee pristine nanostructures and vice versa. Structural preservation of bone from macro- to nanoscale primarily depends on original bioapatite density, and subsequent taphonomical factors such as effects from burial, pressure, influx of external elements and the rate of diagenetic alteration of apatite crystals. Our findings suggest that the efficient application of SAED analysis opens the opportunity for comprehensive nanostructural investigations of bone.

Correlative microscopy of the constituents of a dinosaur rib fossil and hosting mudstone: Implications on diagenesis and fossil preservation.

We have applied correlative microscopy to identify the key constituents of a dorsal rib fossil from Koreanosaurus boseongensis and its hosting mudstone discovered at the rich fossil site in Boseong, South Korea, to investigate the factors that likely contributed to diagenesis and the preservation of fossil bone. Calcite and illite were the commonly occurring phases in the rib bone, hosting mudstone, and the boundary region in-between. The boundary region may have contributed to bone preservation once it fully formed by acting as a protective shell. Fluorapatite crystals in the rib bone matrix signified diagenetic alteration of the original bioapatite crystals. While calcite predominantly occupied vascular channels and cracks, platy illite crystals widely occupied miniscule pores throughout the bone matrix. Thorough transmission electron microscopy (TEM) study of illite within the bone matrix indicated the solid-state transformation of 1M to 2M without composition change, which was more evident from the lateral variation of 1M to 2M within the same layer. The high level of lattice disordering of 2M illite suggested an early stage of 1M to 2M transformation. Thus, the diagenetic alteration of both apatite and illite crystals within the bone matrix may have increased its overall density, as the preferred orientation of apatite crystals from moderate to strong degrees was evident despite the poor preservation of osteohistological features. The combined effects of rapid burial, formation of a boundary region, and diagenesis of illite and apatite within the bone matrix may have contributed to the rib bone preservation.

Impact of activator type on the immobilisation of lead in fly ash-based geopolymer.

Immobilisation of heavy metals in geopolymers has attracted attention as a potential means of treating toxic wastes. Lead is known to be effectively immobilised in a geopolymer matrix, but detailed explanation for the mechanisms involved and the specific chemical form of lead are not fully understood. To reveal the effect of the activator types on the immobilisation of lead in geopolymers, 0.5 and 1.0wt% lead in the form of lead nitrate was mixed with fly ash and alkaline activators. Different alkaline activators (either combined sodium hydroxide and sodium silicate or sodium aluminate) were used to achieve the target Si:Al ratios 2.0 and 5.0 in geopolymers. Zeolite was formed in aluminate-activated geopolymers having a Si:Al ratio of 2.0, but the zeolite crystallization was suppressed as lead content increased. No specific crystalline phase of lead was detected by X-ray diffraction, electron diffraction or FT-IR spectrometry. In fact, double Cs corrected TEM analysis revealed that lead was evenly distributed with no evidence of formation of a specific lead compound. A sequential extraction procedure for fractionation of lead showed that lead did not exist as an exchangeable ion in geopolymers, regardless of activator type used. Aluminate activation is shown to be superior in the immobilisation of lead because about 99% of extracted lead existed in the oxidizing and residual fractions.

Close-packed polymer crystals from two-monomer-connected precursors.

The design of crystalline polymers is intellectually stimulating and synthetically challenging, especially when the polymerization of any monomer occurs in a linear dimension. Such linear growth often leads to entropically driven chain entanglements and thus is detrimental to attempts to realize the full potential of conjugated molecular structures. Here we report the polymerization of two-monomer-connected precursors (TMCPs) in which two pyrrole units are linked through a connector, yielding highly crystalline polymers. The simultaneous growth of the TMCP results in a close-packed crystal in polypyrrole (PPy) at the molecular scale with either a hexagonal close-packed or face-centred cubic structure, as confirmed by high-voltage electron microscopy, and the structure that formed could be controlled by simply changing the connector. The electrical conductivity of the TMCP-based PPy is almost 35 times that of single-monomer-based PPy, demonstrating its promise for application in diverse fields.

Langmuir monolayers of Co nanoparticles and their patterning by microcontact printing.

In this paper, we describe an easy and reliable method for the production of patterned monolayers of Co nanoparticles. A two-dimensional monolayer of Co nanoparticles is fabricated by spreading a nanoparticle solution over an air-water interface and then transferring it to a hydrophobic substrate by using the Langmuir-Blodgett (LB) method. Transmission electron microscopy (TEM) was used to show that, with increasing surface pressure, the Co nanoparticles become well-organized into a Langmuir monolayer with a hexagonal close-packed structure. By controlling the pH of the subphase, it was found that a monolayer of Co nanoparticles with long-range order could be obtained. Further, by transferring the Langmuir monolayer onto a poly(dimethoxysilane) (PDMS) mold, the selective micropatterning of the Co nanoparticles could be achieved on a patterned electronic circuit. The electronic transport properties of the Co nanoparticles showed the ohmic I-V curve.

Gene delivery of PAMAM dendrimer conjugated with the nuclear localization signal peptide originated from fibroblast growth factor 3.

Polyamidoamine (PAMAM) is one of the widely employed non-viral vectors in gene therapy research, and shows excellent biocompatibility and relatively low cytotoxicity. However, it has poor transfection efficiency compared with that of polyethylenimine (PEI, 25 kDa). To enhance the gene expression efficiency, we introduced the RRRK peptide from mouse fibroblast growth factor 3 (FGF3) to PAMAM, which is a known nuclear localization signal (NLS). We synthesized PAMAM-KRRR and PAMAM-RRRK to verify the difference of the induced functional status from reversal of the N-terminus. PAMAM containing the FGF3 peptide showed a transfection efficiency corresponding to that of PEI in HEK293, and HeLa cells, and showed much higher gene expression capacity than that of PEI in NIH3T3 cells with relatively decreased cytotoxicity. These results imply that introduction of the FGF 3 peptide has the potential to provide a novel PAMAM-based vector by enhancing its gene expression efficiency.

Ectopic presence of tooth within the mandibular condyle.

This article describes the case of a 41-year-old woman who presented with the complaint of crepitation sound and mild pain in the left temporomandibular joint area. Panoramic radiographs taken to rule out degenerative or arthritic changes in the joints demonstrated a radiopaque mass within the left condyle. Cone beam computed tomography scans revealed an ectopic tooth located centrally within the left condyle. Thus, while considered rare, the mandibular condyle can be a possible location of an ectopic tooth.

Molecular level ordering in poly(2-vinylpyridine).

The reaction between atactic poly(2-vinylpyridine) and 1,4-dibromobutane leads to formation of long-range 3D molecular ordering in polymer chains mainly because the side group (pyridine) of the polymer chain changes to a syndotactic configuration. This may enable the production of functional molecular devices that operate on a 3D atomic scale.