Cooperative formation of porous silica and peptides on the prebiotic Earth.

Modern technology has perfected the synthesis of catalysts such as zeolites and mesoporous silicas using organic structure directing agents (SDA) and their industrial use to catalyze a large variety of organic reactions within their pores. We suggest that early in prebiotic evolution, synergistic interplay arose between organic species in aqueous solution and silica formed from rocks by dynamic dissolution-recrystallization. The natural organics, for example, amino acids, small peptides, and fatty acids, acted as SDA for assembly of functional porous silica structures that induced further polymerization of amino acids and peptides, as well as other organic reactions. Positive feedback between synthesis and catalysis in the silica-organic system may have accelerated the early stages of abiotic evolution by increasing the formation of polymerized species.

Self-emitting blue and red EuOX (X = F, Cl, Br, I) materials: band structure, charge transfer energy, and emission energy.

Self-emitting blue and red EuOX (X = F, Cl, Br, and I) were successfully synthesized and characterized. Far-infrared and Raman measurements revealed that the vibration modes prominently reflected the Eu-O and Eu-X bond characters of these materials. X-ray photoelectron spectroscopy (XPS) of the red-emitting EuOX compounds showed that Eu exclusively existed as Eu3+, while in the blue-emitting EuOX, a mixed Eu3+/Eu2+ state was observed. For the red-emitting EuOX (X = F, Cl, and Br), the maximum wavelengths of the charge-transfer (CT) bands were red-shifted: F → Cl → Br (282, 320, and 330 nm for F, Cl, and Br, respectively). Using one-electron spin-polarized band structure calculations, it was verified that the red-shift of the CT energy from F to Br in EuOX was mainly due to the relative positions of the halogen orbital energies being gradually increased, following the trend in their electronegativity. For the blue-emitting EuOX (X = Cl, Br, and I), the emission band maxima were red-shifted from Cl to I (409, 414, and 432 nm for Cl, Br, and I, respectively), which was quite opposite to the trend predicted based on the spectrochemical series in crystal field theory, which was in good agreement with the previous results of the calculated 5d → 4f transition energies of the Eu2+ activator based on the crystal field theory. Through photoluminescence, UV-visible absorbance, and XPS, it was elucidated that the red emission due to Eu3+ was strongly masked by the intensified blue emission associated with the small amount of Eu2+ in the blue-emitting EuOX (X = Cl, Br, and I). These materials may provide a platform for modeling new phosphors for application in solid-state lighting.

Tracking Single DNA Nanodevices in Hierarchically Meso-Macroporous Antimony-Doped Tin Oxide Demonstrates Finite Confinement.

Housing bio-nano guest devices based on DNA nanostructures within porous, conducting, inorganic host materials promise valuable applications in solar energy conversion, chemical catalysis, and analyte sensing. Herein, we report a single-template synthetic development of hierarchically porous, transparent conductive metal oxide coatings whose pores are freely accessible by large biomacromolecules. Their hierarchal pore structure is bimodal with a larger number of closely packed open macropores (∼200 nm) at the higher rank and with the remaining space being filled with a gel network of antimony-doped tin oxide (ATO) nanoparticles that is highly porous with a broad size range of textual pores mainly from 20-100 nm at the lower rank. The employed carbon black template not only creates the large open macropores but also retains the highly structured gel network as holey pore walls. Single molecule fluorescence microscopic studies with fluorophore-labeled DNA nanotweezers reveal a detailed view of multimodal diffusion dynamics of the biomacromolecules inside the hierarchically porous structure. Two diffusion constants were parsed from trajectory analyses that were attributed to free diffusion (diffusion constant D = 2.2 µm2/s) and to diffusion within an average confinement length of 210 nm (D = 0.12 µm2/s), consistent with the average macropore size of the coating. Despite its holey nature, the ATO gel network acts as an efficient barrier to the diffusion of the DNA nanostructures, which is strongly indicative of physical interactions between the molecules and the pore nanostructure.

Unusual Changes in Electronic Band-Edge Energies of the Nanostructured Transparent n-Type Semiconductor Zr-Doped Anatase TiO2 (Ti1-xZrxO2; x < 0.3).

By the establishment of highly controllable synthetic routes, electronic band-edge energies of the n-type transparent semiconductor Zr-doped anatase TiO2 have been studied holistically for the first time up to 30 atom % Zr, employing powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, nitrogen gas sorption measurements, UV/vis spectroscopies, and Mott-Schottky measurements. The materials were produced through a sol-gel synthetic procedure that ensures good compositional homogeneity of the materials, while introducing nanoporosity in the structure, by achieving a mild calcination condition. Vegard's law was discovered among the homogeneous samples, and correlations were established between the chemical compositions and optical and electronic properties of the materials. Up to 20% Zr doping, the optical energy gap increases to 3.29 eV (vs 3.19 eV for TiO2), and the absolute conduction band-edge energy increases to -3.90 eV (vs -4.14 eV). The energy changes of the conduction band edge are more drastic than what is expected from the average electronegativities of the compounds, which may be due to the unnatural coordination environment around Zr in the anatase phase.

Nanoporous delafossite CuAlO2 from inorganic/polymer double gels: a desirable high-surface-area p-type transparent electrode material.

Nanoporous structures of a p-type semiconductor, delafossite CuAlO(2), with a high crystallinity have been fabricated through an inorganic/polymer double-gel process and characterized for the first time via Mott-Schottky measurements. The effect of the precursor concentration, calcination temperature, and atmosphere were examined to achieve high crystallinity and photoelectrochemical properties while maximizing the porosity. The optical properties of the nanoporous CuAlO(2) are in good agreement with the literature with an optical band gap of 3.9 eV, and the observed high electrical conductivity and hole concentrations conform to highly crystalline and well-sintered nanoparticles observed in the product. The Mott-Schottky plot from the electrochemical impedance spectroscopy studies indicates a flat-band potential of 0.49 V versus Ag/AgCl. It is concluded that CuAlO(2) exhibits band energies very close to those of NiO but with electrical properties very desirable in the fabrication of photoelectrochemical devices including dye-sensitized solar cells.

High performance CNT point emitter with graphene interfacial layer.

Carbon nanotubes (CNTs) have great potential in the development of high-power electron beam sources. However, for such a high-performance electronic device, the electric and thermal contact problem between the metal and CNTs must be improved. Here, we report graphene as an interfacial layer between the metal and CNTs to improve the interfacial contact. The interfacial graphene layer results in a dramatic decrease of the electrical contact resistance by an order of 2 and an increase of the interfacial thermal conductivity by 16%. Such a high improvement in the electrical and thermal interface leads to superior field emission performance with a very low turn-on field of 1.49 V µm(-1) at 10 µA cm(-2) and a threshold field of 2.00 V µm(-1) at 10 mA cm(-2), as well as the maximum current of 16 mA (current density of 2300 A cm(-2)).

Twistable and bendable actuator: a CNT/polymer sandwich structure driven by thermal gradient.

We demonstrate a novel configuration of an electrothermal actuator (ETA), which is based on a polydimethylsiloxane (PDMS) slab sandwiched by upper and lower active layers of CNT-PDMS composite. When only one active layer of a single sandwich structure ETA is heated and the other is not, there exists a thermal gradient in the direction of the slab thickness, resulting in bending motion toward the unheated side. Moreover, a dual sandwich structure ETA, consisting of two parallel assembled sandwich structures on the same body, has the unique ability to act with a twisting motion as the two ETAs bend in opposite directions. We expect the advent of the bendable and twistable actuator to break new ground in ETAs.

Synthesis and Characterization of Dispersible Geopolymer Nanoaggregates.

We present a simple synthetic route to submicron-sized both potassium- and sodium-based geopolymer nanoaggregates whose nanostructure is suitable for applications in polymer composites. The new synthetic method is based on the chemical mechanism of geopolymer formation in which the extent of cross-liking of geopolymer primary particles is dependent of the alkali concentration and the relative amount of water in the precursor mixture. The products exhibited ∼50-60 nm-sized primary particles along with ∼15-20 nm-sized smaller particles. The external surface areas of the products were high, up to 231 m2/g, especially for the sodium-based geopolymer. The primary particles are fused together to form aciniform nanoaggregates with average size of about 400 nm and mesopore volume up to about 0.59 cm3/g. The zeta potential of the nanoaggregates was below ‒ 40 mV in the pH range of 5.7-12, demonstrating that the particles are stable in this pH region and do not undergo aggregation and/or agglomeration. All these characteristics make the new material favorable in application of the material in nanofiller application.

Crystal-like growth of a metal oxide/CNT composite fiber with electroplated "seed" from a CNT-dispersed nonaqueous electrolyte.

A fabrication technique is developed for the preparation of metal oxide/CNT composites. An essential feature of the technique lies in the use of nonaqueous electrolyte in place of the usual aqueous electrolyte, which ensures well-dispersed CNTs without surfactants. After a "seed" is formed by electroplating on the anode, the seed is simply pulled up at a certain speed to grow a 1D CNT composite structure. The technique leads to a uniform distribution of metal oxide and a high weight fraction of CNT in the composite structure. Moreover, the conductivity of the composite is much higher than that of the CNT fibers fabricated with polymer.

Selective oxidation of n-buthanol to butyraldehyde over MnCo2O4 spinel oxides.

Partial oxidation of n-butanol to butyraldehyde, propionaldehyde and acetaldehyde over MnCo2O4 spinel oxides has been investigated. Physicochemical characteristics of samples, prepared by co-precipitation with different amounts of precipitating agent, were studied by XRD, N2 adsorption-desorption isotherms, FT-IR, SEM and XPS. The ratio between the precipitating agent and the precursors has a considerable influence both on the structure, which is evidenced by XRD, due to switching from a crystalline structure to an amorphous one and on the surface (XPS) by an obvious change in the ratio Co3+/Co2+ and Mn4+/Mn3+ and in the content of oxygen vacancies. The reaction rate is not influenced by the oxygen pressure, emphasizing that n-butanol oxidation occurs through the Mars van Krevelen mechanism. The conversion of n-butanol and yield of butyraldehyde are directly proportional to the cobalt content on the surface, while the propionaldehyde yield is proportional to the Mn4+/Mn3+ ratio.

Synthesized Geopolymers Adsorb Bacterial Proteins, Toxins, and Cells.

Pore-forming and hemolytic toxins are bacterial cytotoxic proteins required for virulence in many pathogens, including staphylococci and streptococci, and are notably associated with clinical manifestations of disease. Inspired by adsorption properties of naturally occurring aluminosilicates, we engineered inexpensive, laboratory-synthesized, aluminosilicate geopolymers with controllable pore and surface characteristics to remove pathogenic or cytotoxic material from the surrounding environment. In this study, macroporous and mesoporous geopolymers were produced with and without stearic acid surface modifications. Geopolymer binding efficacies were assessed by measuring adsorption of methicillin-resistant Staphylococcus aureus (MRSA) culture filtrate proteins, α-hemolysin and streptolysin-O toxins, MRSA whole cells, and antibiotics. Macroporous and mesoporous geopolymers were strong non-selective adsorbents for bacterial protein, protein toxins, and bacteria. Although some geopolymers adsorbed antibiotics, these synthesized geopolymers could potentially be used in non-selective adsorptive applications and optimized for adsorption of specific biomolecules.

Optimal illumination for discriminating objects with different spectra.

Color differences are determined by illumination, the spectral reflectance of objects, and the spectral sensitivity of the imaging sensor. We explore the optimal illumination conditions that best separate one object from another. Given two objects with distinct spectra, we derive the optimal illumination spectrum to maximize their color distance with a plain RGB camera. In practice, it is crucial to compose the most appropriate illuminations using available lighting sources, since creating an arbitrary illumination spectrum is unrealistic. Therefore, we derive the optimal linear combination of the provided illumination sources. Finally, we verify the effectiveness of the methods through experiments.

Molybdenum Dopped Copper Ferrites as Active Catalysts for Alcohols Oxidative Coupling.

Copper ferrites dopped with molybdenum were studied in an oxidative coupling reaction between methanol and ethanol in the gas phase. The catalysts have been characterized by X-ray diffraction, where the presence of ferrite, magnetite, and tenorite phases was observed; scanning electron microscopy; UV-Vis spectroscopy; and Fourier-transform infrared spectroscopy, which highlighted the presence of octahedral coordination of isolated molybdena species. The catalyst with the highest activity in this reaction and with the highest selectivity to hydroxyacetone is the one that presents Lewis sites with weak acidity. The methyl and ethyl acetate selectivities are directly proportional to the Cu/Fe ratio. It has been observed that the presence of reduced copper sites is responsible for the selectivity in esters, while the presence of reduced iron and molybdenum sites is responsible for the acetol production.

Combined epidural adhesiolysis and balloon decompression can be effective in intractable lumbar spinal stenosis patients unresponsive to previous epidural adhesiolysis.

Moderate evidence exists regarding percutaneous epidural adhesiolysis (PEA) being an effective treatment for lumbar spinal stenosis (LSS). Although PEA is successfully performed using balloon-less epidural catheters, many patients with severe adhesions cannot obtain satisfactory results. Combined treatment with balloon-inflatable catheters for PEA and balloon decompression recently demonstrated sufficient pain relief and functional improvement in patients with intractable LSS. We compared the effects of PEA and balloon decompression in patients with intractable LSS who did not undergo PEA and those who were unresponsive to previous PEA with a balloon-less catheter.We examined 315 patients who underwent PEA and balloon decompression with balloon-inflatable catheters. Patients with intractable LSS were divided into those without previous PEA (No-PEA) and those unresponsive to previous PEA using balloon-less catheters (Prev-PEA). The numeric rating scale, Oswestry disability index, and global perceived effect of satisfaction scale were measured at 0, 1, 3, and 6 months after the intervention. Responder analysis was performed based on changes in measured scales and indices.A successful treatment response was observed at 1, 3, and 6 months after the intervention in 56.4%, 42.7%, and 32.9%, respectively, of the No-PEA group and in 48.9%, 37.8%, and 25.6%, respectively, of the Prev-PEA group. No significant between-group differences were detected. Pain intensities and functional status improved and were maintained throughout follow-up after PEA with balloon decompression using balloon-inflatable catheters.This modality may represent a useful alternative to overcome the limitations of preexisting adhesiolysis procedures.

Predictors of Response to a Medial Branch Block: MRI Analysis of the Lumbar Spine.

The aim of this study was to determine the association between radiologic spinal pathology and the response to medial branches block (MBB). This retrospective observational study compared 165 patients. A successful response was defined as ≥30% or a 2-point reduction in the numeric rating scale (NRS) compared with the baseline at the 1-month follow-up. The facet angle, facet angle difference, facet joint degeneration, disc height and spondylolisthesis grade were analyzed from an MRI at the L3 to S1 levels. Univariate and multivariate logistic regression analyses were used to evaluate independent factors associated with a successful response of MBB. In the univariate analysis, the disc height at L5-S1 and facet angle difference at L3-4 were lower in the positive responders (p = 0.022 and p = 0.087, respectively). In the multivariate analysis, the facet angle difference at L3-4 and disc height at L5-S1 were independent factors associated with a successful response (odds ratio = 0.948; p = 0.038 and odds ratio = 0.864; p = 0.038, respectively). In patients with a degenerative disc at L5-S1, MBB can lead to a good response for at least one month. In patients with facet tropism at L3-4 level, the response to MBB after one month is likely to be poor.

Two-dimensional superdegeneracy and structure-magnetism correlations in strong ferromagnet, Mn2Ga5.

The ferromagnetic intermetallic compound Mn2Ga5 has been synthesized and characterized by single-crystal X-ray diffraction study and by magnetic property measurements. The compound, with the Mn2Hg5-type structure, exhibits a saturated magnetic moment of 2.71 muB per formula unit with T(C) approximately = 450 K. The electronic structure of the compound was analyzed by employing FPLO, LMTO, and the extended Hückel tight-binding calculations. The nonmagnetic electronic structure of Mn2Ga5 reveals remarkably flat degenerate (superdegenerate) bands in the vicinity of the Fermi level but only in the a*b*-plane of the Brillouin zone. The resulting high density of the states at the Fermi level, DOS(E(F)), is consistent with the Stoner condition for the observed itinerant electron ferromagnetism. Detailed orbital analysis shows an intriguing structure-magnetism correlation, as the superdegeneracy is found to be a consequence of the unique atomic arrangement and bond angles in the structure.

Nature of Stoner condition for metallic ferromagnetism.

For proper applications of the Stoner condition, we describe the assumptions in its underlying theory and their implications that need to be considered in practice. The nature of Stoner exchange parameters is examined based on spin-polarization perturbational orbital theory and a connection has been made in understanding the parameters with both local spin density and Hartree-Fock approximations via a self-interaction-corrected local spin density (SIC-LSD) exchange-correlation functional.

Orbital interpretation of kinetic energy density and a direct space comparison of chemical bonding in tetrahedral network solids.

We present how the kinetic energy density (KED) can be interpreted on the basis of the orbital interactions within the Kohn-Sham theory and propose how to utilize a direct space function in chemical bonding analysis, the relative entropy density (RED), which is constructed from the KED, the Thomas-Fermi KED (TF-KED), and the electron density. From the detailed analysis of the KED of wave functions and the TF-KED from the free electron model, it is shown that the RED can reveal the nodal properties of individual wave functions and provide a variationally meaningful way of accumulating chemical bonding information from the wave functions, hence allowing quantitative bonding analysis in direct space. To substantiate the proposal, the RED function has been tested on the tetrahedral network solids, including the group 14 elements and the III-V binary compounds with the zinc blende structure. The direct space maps of the RED quantitatively reflect the trend in metallicity and the polarity of their two-center, two-electron bonds in terms of the absolute values of the RED, the location of the minimum values, and the behavior of the deformation from the spherical symmetry of the atomic RED.

Retrodiscal epidural balloon adhesiolysis through Kambin's triangle in chronic lumbar spinal stenosis: A retrospective analysis and technical considerations.

A previous study showed that transforaminal balloon adhesiolysis via the safe triangle was effective in lumbar spinal stenosis. However, retrodiscal pathology is difficult to treat with this method. Therefore we attempted retrodiscal balloon adhesiolysis via Kambin's triangle. The design of our study is a retrospective analysis. The setting of our study is a tertiary, interventional pain management practice, speciality referral center.The primary indication for this procedure is radicular pain arising from ipsilateral retrodiscal pathology. Medical records were reviewed of patients who received retrodiscal decompression with a transforaminal balloon inflatable catheter between January 1, 2016 and July 31, 2017. The intervention was conducted by 2 well-trained pain specialists. The introducer needle was positioned at Kambin's triangle. Adhesiolysis was performed using a balloon filled with radiocontrast media. After balloon adhesiolysis, an agent containing lidocaine and dexamethasone was injected through the introducer sheath. Numeric rating scale pain scores were obtained 1 and 3 months after the procedure.The mean pre-procedure numeric rating scale score was 7.05 ±â€Š1.40. After 1 and 3 months, the mean scores were 3.91 ±â€Š2.20 and 3.77 ±â€Š2.11, respectively. No patient had significant complications. Also, technical considerations were discussed.Chronic pain due to lumbar central stenosis, especially ipsilateral retrodiscal pathology, can be reduced by retrodiscal balloon adhesiolysis through Kambin's triangle. Although this study is limited by its retrospective design, the results suggest that this procedure is a useful treatment due to its ease of performance and cost-effectiveness.

Superior ion release properties and antibacterial efficacy of nanostructured zeolites ion-exchanged with zinc, copper, and iron.

Antimicrobial zeolites ion-exchanged with inexpensive transition metal ions (such as zinc, copper, and iron) are critically important for a broader adoption of the materials for public health applications. Due to the high surface area and small particle sizes, nanozeolites are particularly promising in enhancing the efficacy of the zeolite-based antimicrobial materials. By using highly-crystalline nanostructured zeolites (FAU) with textural mesoporosity, we report a comprehensive study on the materials characteristics of zinc-, copper-, and iron-ion exchanged nanozeolites, the ion release properties, and antibacterial efficacy against methicillin-resistant Staphylococcus aureus (MRSA), as well as a comparison of the properties to those obtained for the corresponding microsized zeolites. Superior ion release properties were observed for both zinc and copper ion-exchanged nanostructured zeolite X, with ion release up to 73% for zinc and 36% for copper of their initial loadings, as compared to 50% and 12%, respectively, for the corresponding microsized zeolites, validating the importance of nanostructuring for enhanced ion diffusion through zeolite pore channels. The 2 hours minimum bactericidal concentration (MBC) in saline for the copper ion-exchanged nanostructured zeolite X was 32 µg mL-1, half the corresponding microsized zeolite X MBC of 64 µg mL-1. Our results established nanostructured zeolite X as a superior host material for metal ion-based antimicrobials, with the aforementioned improvements for copper-exchanged nanozeolites compared to previous studies.