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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Epidural blood patch treatment of diplopia that developed after headache resolution in a patient with spontaneous intracranial hypotension.

Sudden headache onset may rarely be caused by spontaneous intracranial hypotension (SIH). Other associated symptoms in patients with SIH are nausea, vomiting, vertigo, hearing alteration, and visual disturbance. This case report describes a 43-year-old female diagnosed with SIH who developed diplopia after resolution of an abrupt-onset headache, which was managed with conservative treatments, including bed rest and hydration. She was also diagnosed with secondary right sixth cranial nerve palsy. Although conservative management relieved her headache, the diplopia was not fully relieved. Application of an autologous epidural blood patch successfully relieved her diplopia, even after 14 days from the onset of visual impairment.

Ultrasound-Guided Genicular Nerve Block for Knee Osteoarthritis: A Double-Blind, Randomized Controlled Trial of Local Anesthetic Alone or in Combination with Corticosteroid.

BACKGROUND: Recently, several studies suggested that radiofrequency (RF) ablation of the genicular nerves is a safe and effective therapeutic procedure for intractable pain associated with chronic knee osteoarthritis (OA). Diagnostic genicular nerve block (GNB) with local anesthetic has been generally conducted before making decisions regarding RF ablation. Although GNB has been recently performed together with corticosteroid, the analgesic effects of corticosteroids for treating chronic pain remain controversial. OBJECTIVES: The current study aims to assess the effects of combining corticosteroids and local anesthesia during ultrasound-guided GNB in patients with chronic knee OA. STUDY DESIGN: A randomized, double-blinded institutional study. SETTING: This study took place at Asan Medical Center in Seoul, Korea. METHODS: Forty-eight patients with chronic knee OA were randomly assigned to either the lidocaine alone group (n = 24) or lidocaine plus triamcinolone (TA) group (n = 24) before ultrasound-guided GNB. Visual analog scale (VAS), Oxford Knee Score (OKS), and global perceived effects (7-point scale) were assessed at baseline and at 1, 2, 4, and 8 weeks after the procedure. RESULTS: The VAS scores were significantly lower in the lidocaine plus TA group than in the lidocaine alone group at both 2 (P < 0.001) and 4 (P < 0.001) weeks after GNB. The alleviation of intense pain in the lidocaine plus TA group was sustained up to 2 weeks after the procedure, in accordance with the definition of a minimal clinically important improvement. Although a similar intergroup difference in OKSs was observed at 4 weeks (P < 0.001), the clinical improvement in functional capacity lasted for only one week after the reassessment of OKSs, in accordance with a minimal important change. No patient reported any postprocedural adverse events during the follow-up period. LIMITATIONS: The emotional state of the patients, which might affect the perception of knee pain, was not evaluated. The follow-up period was 2 months; this period might be insufficient to validate the short-term effects of GNB. CONCLUSIONS: Ultrasound-guided GNB, when combined with a local anesthetic and corticosteroid, can provide short-term pain relief. However, the clinical benefit of corticosteroid administration was not clear in comparison with local anesthesia alone. Given the potential adverse effects, corticosteroids might not be appropriate as adjuvants during a GNB for chronic knee OA.The study protocol was approved by our institutional review board (2012-0210), and written informed consent was obtained from all patients. The trial was registered with the Clinical Research Information Service (KCT 0001139). KEY WORDS: Chronic pain, knee osteoarthritis, genicular nerve block, ultrasound, corticosteroid, local anesthetic, visual analog scale, Oxford Knee Score.

Template-free synthesis and structural evolution of discrete hydroxycancrinite zeolite nanorods from high-concentration hydrogels.

We report the synthesis and characterization of hydroxycancrinite zeolite nanorods by a simple hydrothermal treatment of aluminosilicate hydrogels at high concentrations of precursors without the use of structure-directing agents. Transmission electron microscopy (TEM) analysis reveals that cancrinite nanorods, with lengths of 200-800 nm and diameters of 30-50 nm, exhibit a hexagonal morphology and are elongated along the crystallographic c direction. The powder X-ray diffraction (PXRD), Fourier transform infrared (FT-IR) and TEM studies revealed sequential events of hydrogel formation, the formation of aggregated sodalite nuclei, the conversion of sodalite to cancrinite and finally the growth of cancrinite nanorods into discrete particles. The aqueous dispersion of the discrete nanorods displays a good stability between pH 6-12 with the zeta potential no greater than -30 mV. The synthesis is unique in that the initial aggregated nanocrystals do not grow into microsized particles (aggregative growth) but into discrete nanorods. Our findings demonstrate an unconventional possibility that discrete zeolite nanocrystals could be produced from a concentrated hydrogel.

Silver-Ion-Exchanged Nanostructured Zeolite X as Antibacterial Agent with Superior Ion Release Kinetics and Efficacy against Methicillin-Resistant Staphylococcus aureus.

As antibiotic resistance continues to be a major public health problem, antimicrobial alternatives have become critically important. Nanostructured zeolites have been considered as an ideal host for improving popular antimicrobial silver-ion-exchanged zeolites, because with very short diffusion path lengths they offer advantages in ion diffusion and release over their conventional microsized zeolite counterparts. Herein, comprehensive studies are reported on materials characteristics, silver-ion release kinetics, and antibacterial properties of silver-ion-exchanged nanostructured zeolite X with comparisons to conventional microsized silver-ion-exchanged zeolite (∼2 µm) as a reference. The nanostructured zeolites are submicrometer-sized aggregates (100-700 nm) made up of primary zeolite particles with an average primary particle size of 24 nm. The silver-ion-exchanged nanostructured zeolite released twice the concentration of silver ions at a rate approximately three times faster than the reference. The material exhibited rapid antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA) with minimum inhibitory concentration (MIC) values ranging from 4 to 16 µg/mL after 24 h exposure in various growth media and a minimum bactericidal concentration (MBC; >99.9% population reduction) of 1 µg/mL after 2 h in water. While high concentrations of silver-ion-exchanged nanostructured zeolite X were ineffective at reducing MRSA biofilm cell viability, efficacy increased at lower concentrations. In consideration of potential medical applications, cytotoxicity of the silver-ion-exchanged nanostructured zeolite X was also investigated. After 4 days of incubation, significant reduction in eukaryotic cell viability was observed only at concentrations 4-16-fold greater than the 24 h MIC, indicating low cytotoxicity of the material. Our results establish silver-ion-exchanged nanostructured zeolites as an effective antibacterial material against dangerous antibiotic-resistant bacteria.

Enhancing Photocurrent Generation in Photosynthetic Reaction Center-Based Photoelectrochemical Cells with Biomimetic DNA Antenna.

Three- to four-times higher performance of biohybrid photoelectrochemical cells with photosynthetic reaction centers (RC) has been achieved by using a DNA-based biomimetic antenna. Synthetic dyes Cy3 and Cy5 were chosen and strategically placed in the anntena in such a way that they can collect additional light energy in the visible region of the solar spectrum and transfer it to RC through Förster resonance energy transfer (FRET). The antenna, a DNA templated multiple dye system, is attached to each Rhodobacter sphaeroides RC near the primary donor, P, to facilitate the energy transfer process. Excitation with a broad light spectrum (approximating sunlight) triggers a cascade of excitation energy transfer from Cy3 to Cy5 to P, and also directly from Cy5 to P. This additional excitation energy increases the RC absorbance cross-section in the visible and thus the performance of the photoelectrochemical cells. DNA-based biomimetic antennas offer a tunable, modular light-harvesting system for enhancing RC solar coverage and performance for photoelectrochemical cells.

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.

Equipment-Free Deposition of Graphene-Based Molybdenum Oxide Nanohybrid Langmuir-Blodgett Films for Flexible Electrochromic Panel Application.

The potential electrochromic application of graphene-based nanohybrids is hampered by the challenges in interfacing the electrochromic nanoparticles with graphene at atomic scale and in fabricating their thin film on the substrate through a scalable method. In an effort to overcome these challenges, we demonstrate a highly dispersible graphene-based molybdenum oxide nanohybrid (mRGO-MoO3-x) for flexible electrochromic application. With only a squeeze pipet, mRGO-MoO3-x could be deposited with a high coverage on various substrates through a scalable equipment-free Langmuir-Blodgett film deposition method. By taking advantage of high transmittance benefited from its remarkable thinness, the mRGO-MoO3-x Langmuir-Blodgett film shows a superior reversible electrochromic property with high coloration efficiency on both hard and flexible substrates.

Photocurrent Generation by Photosynthetic Purple Bacterial Reaction Centers Interfaced with a Porous Antimony-Doped Tin Oxide (ATO) Electrode.

The ability to exchange energy and information between biological and electronic materials is critical in the development of hybrid electronic systems in biomedicine, environmental sensing, and energy applications. While sensor technology has been extensively developed to collect detailed molecular information, less work has been done on systems that can specifically modulate the chemistry of the environment with temporal and spatial control. The bacterial photosynthetic reaction center represents an ideal photonic component of such a system in that it is capable of modifying local chemistry via light-driven redox reactions with quantitative control over reaction rates and has inherent spectroscopic probes for monitoring function. Here a well-characterized model system is presented, consisting of a transparent, porous electrode (antimony-doped tin oxide) which is electrochemically coupled to the reaction center via a cytochrome c molecule. Upon illumination, the reaction center performs the 2-step, 2-electron reduction of a ubiquinone derivative which exchanges with oxidized quinone in solution. Electrons from the electrode then move through the cytochrome to reoxidize the reaction center electron donor. The result is a facile platform for performing redox chemistry that can be optically and electronically controlled in time and space.

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.