Nanoparticle Superlattices Driven by Linker-Mediated Covalent Bonding Interaction.

The stability of the nanoparticle superlattice (NPSL) is essential for realizing its broad spectrum of potential applications. Here, we report a linker-mediated covalent bonding interaction method for the synthesis of highly stable NPSLs. Adipic acid is used as a linker molecule which connects two Au NPs functionalized with 6-mercaptohexanol through esterification reactions in the presence of H2SO4. As-prepared NPSLs are mostly fcc Wulff polyhedra with a fairly narrow size distribution and are highly stable in solvents of different polarities and pHs (0-14) as well as in dry conditions and at temperatures as high as 175 °C. The formation of NPSLs involves random homogeneous nucleation simultaneously accompanied by growth, a gradual change of the growth mode from reaction-controlled to diffusion-controlled with time, and the oriented attachments of small crystals. The size of the NPSL can be easily tuned by the concentration of linker molecules and the reaction temperature.

Evaluation of the efficacy and safety of Yukwool-tang for major depressive disorder in women: A randomized, double blinded, placebo-controlled, parallel trial.

BACKGROUND: Major depressive disorder (MDD) occurs more often in women than that in men due to various complex causes. This study aimed to evaluate the effectiveness and safety of Yukwool-tang (YWT) for MDD in women. METHODS: A total of 72 patients diagnosed with MDD and Korean version of the Hamilton Depression Rating Scale (K-HDRS) ≥ 14 points were randomly assigned to the YWT or placebo group, and 1 bottle (30 mg) of No-S solution and placebo was administered to the YWT and placebo groups, respectively, orally thrice a day for 8 weeks. The evaluation was conducted through K-HDRS, Korean version of the Beck Depression Inventory (BDI-K), Korean version of the Beck Hopelessness Scale (K-BHS), Korean version of the Insomnia Severity Index (ISI-K), State-Trait Anxiety Inventory (STAI-K), EuroQol-5 dimension (EQ-5D), and Pattern Identifications Tool for Depression (PITD). Fifty patients completed the trial. RESULTS: In the YWT group, the K-HDRS, BDI-K, K-BHS, ISI-K, STAI-K, and EQ-5D scores changed significantly at the 8th week, but there were no significant differences with the placebo. In subgroup analysis, the K-BHS score with an initial K-HDRS score < 18 points was significantly decreased compared to placebo at the 12th week (P < .05). In the YWT group, the ratio of Stagnation of Liver Gi () was the highest, but Dual Deficiency of the Heart and Spleen () became the highest after administration, which was also the highest in the placebo group both before and after administration. CONCLUSION: YWT improved depression and accompanying symptoms in women with MDD, although it was not significant compared to placebo, and it might be effective in improving the degree of hopelessness. The effect of YWT will become relatively clear through further research that can overcome certain limitations.

Expanded Orientation of Urban Public Health Policy in the Climate Change Era: Response to and Prevention of Heat Wave in Paris and Seoul: A Brief Review.

The policies of response to and prevention of heat waves in France in 2003 and in South Korea in 2018 were compared and reviewed to see how public health policy orientation was being expanded in connection with urban and social policies. The statistics of the patients with heat illness and resulted death in France in 2003 and South Korea in 2018 were analyzed. The results and limitations of the French and Korean responses to heat waves were compared and discussed. The heat wave in France in 2003 caused an excess death of 14,802. The 2018 heat wave in South Korea resulted in 4,526 cases of heat illness and 48 deaths. France's National Heat wave Plan established in 2004 introduced the warning system and strengthened support for the vulnerable. The heat wave in South Korea in 2018 revealed the success and limitations of the national measures that have been gradually implemented since the mid-2000s. Both France and South Korea are making efforts in preventing heat illness and managing health risk through the warning systems, providing public and social support for the vulnerable, and expanding urban infrastructure. Paris puts priority on the long-term prevention of heat wave, in the wider context of climate change response, while Seoul shows a relatively strong point in immediate infrastructural expansion. In order to respond to the climate crisis and the following health risk, public health policies need to be contrived with deeper connection with urban social policies for sustainable development.

Clinical Characteristics of Macrolide-Refractory Mycoplasma pneumoniae Pneumonia in Korean Children: A Multicenter Retrospective Study.

Mycoplasma pneumoniae is a major causative pathogen of community-acquired pneumonia in children, and the treatment of choice is macrolides. There is an increasing trend in reports of refractory clinical responses despite macrolide treatment due to the emergence of macrolide-resistant M. pneumoniae. Early discrimination of macrolide-refractory M. pneumoniae pneumonia (MrMP) from macrolide-sensitive M. pneumoniae pneumonia (MSMP) is vital; however, testing for macrolide susceptibility at the time of admission is not feasible. This study aimed to identify the characteristics of MrMP in Korean children, in comparison with those of MSMP. In this multicenter study, board-certified pediatric pulmonologists at 22 tertiary hospitals reviewed the medical records from 2010 to 2015 of 5294 children who were hospitalized with M. pneumoniae pneumonia and administered macrolides as the initial treatment. One-way analysis of variance and the Kruskal-Wallis test were used to compare differences between groups. Of 5294 patients (mean age, 5.6 years) included in this analysis, 240 (4.5%), 925 (17.5%), and 4129 (78.0%) had MrMP, macrolide-less effective M. pneumoniae pneumonia, and MSMP, respectively. Compared with the MSMP group, the MrMP group had a longer fever duration, overall (13.0 days) and after macrolide use (8.0 days). A higher proportion of MrMP patients had respiratory distress, pleural effusion, and lobar pneumonia. The mean aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, and C-reactive protein levels were the highest in the MrMP group, along with higher incidences of extrapulmonary manifestations and atelectasis (during and post infection). Pre-existing conditions were present in 17.4% (n = 725/4159) of patients, with asthma being the most common (n = 334/4811, 6.9%). This study verified that MrMP patients show more severe initial radiographic findings and clinical courses than MSMP patients. MrMP should be promptly managed by agents other than macrolides.

Spontaneous Formation of Highly Stable Nanoparticle Supercrystals Driven by a Covalent Bonding Interaction.

Nanoparticle supercrystals (NPSCs) are of great interest as materials with emergent properties. Different types of intermolecular forces, such as van der Waals interaction and hydrogen bonding, are present in the NPSCs fabricated to date. However, the limited structural stability of such NPSCs that results from the weakness of these intermolecular forces is a challenge. Here, we report a spontaneous formation of NPSCs driven by covalent bonding interactions, a type of intramolecular force much stronger than the above-mentioned intermolecular forces. A model solution-phase anhydride reaction is used to form covalent bonds between molecules grafted on the surface of gold nanoparticles, resulting in three-dimensional NPSCs. The NPSCs are very stable in different solvents, in dried conditions, and at temperatures as high as 160 °C. In addition to this, the large library of covalent-bond-forming reactions available and the low cost of reactants make the covalent bonding approach highly versatile and economical.

Comparative finite element analysis of mandibular posterior single zirconia and titanium implants: a 3-dimensional finite element analysis.

PURPOSE: Zirconia has exceptional biocompatibility and good mechanical properties in clinical situations. However, finite element analysis (FEA) studies on the biomechanical stability of two-piece zirconia implant systems are limited. Therefore, the aim of this study was to compare the biomechanical properties of the two-piece zirconia and titanium implants using FEA. MATERIALS AND METHODS: Two groups of finite element (FE) models, the zirconia (Zircon) and titanium (Titan) models, were generated for the exam. Oblique (175 N) and vertical (175 N) loads were applied to the FE model generated for FEA simulation, and the stress levels and distributions were investigated. RESULTS: In oblique loading, von Mises stress values were the highest in the abutment of the Zircon model. The von Mises stress values of the Titan model for the abutment screw and implant fixture were slightly higher than those of the Zircon model. Minimum principal stress in the cortical bone was higher in the Titan model than Zircon model under oblique and vertical loading. Under both vertical and oblique loads, stress concentrations in the implant components and bone occurred in the same area. Because the material itself has high stiffness and elastic modulus, the Zircon model exhibited a higher von Mises stress value in the abutments than the Titan model, but at a level lower than the fracture strength of the material. CONCLUSION: Owing to the good esthetics and stress controllability of the Zircon model, it can be considered for clinical use.

Preparation of Hot-Melt Extruded Dosage Form for Enhancing Drugs Absorption Based on Computational Simulation.

The aim of this study was to control the dissolution rate and permeability of cilostazol. To enhance the dissolution rate of the active pharmaceutical ingredient (API), hot-melt extrusion (HME) technology was applied to prepare a solid dispersion (SD). To control permeability in the gastrointestinal tract regardless of food intake, the HME process was optimized based on physiologically based pharmacokinetic (PBPK) simulation. The extrudates were produced using a laboratory-scale twin-screw hot-melt extruder with co-rotatory screws and a constant feeding rate. Next, for PBPK simulation, parameter-sensitive analysis (PSA) was conducted to determine the optimization approach direction. As demonstrated by the dissolution test, the solubility of extrudate was enhanced comparing cilostazol alone. Based on the PSA analysis, the surfactant induction was a crucial factor in cilostazol absorption; thus, an extrudate with an even distribution of lipids was produced using hot-melt extrusion technology, for inducing the bile salts in the gastrointestinal tract. In vivo experiments with rats demonstrated that the optimized hot-melt extruded formulation was absorbed more rapidly with lower deviation and regardless of the meal consumed when compared to marketed cilostazol formulations.

Electromagnetic and optical responses of a composite material comprising individual single-walled carbon-nanotubes with a polymer coating.

The composites and thin films comprising individual single-walled carbon nanotubes with a polymer coating (p-CNTs) have been prepared and their electromagnetic responses have been studied in a wide range from low-frequency (25-107 Hz) up to the infrared region. In spite of the high volume fraction of the nanotubes (up to 3.3%), the polymer coating prevents direct p-CNT contacts and the formation of the percolation network in those composites, so that p-CNTs interact only via the electromagnetic coupling. Thereby it is an ideal model system to verify experimentally the fundamental issues related to carbon nanotube electromagnetics, such as the influence of inter-tube electron tunneling on the localized plasmon resonance in the terahertz range, or the infrared absorption enhancement of polymer molecules attached to the nanotube surface. Along with addressing the fundamentals, applied carbon nanotube electromagnetics got insights important for the applications of p-CNT based composites as dielectric media in the terahertz regime. In particular, we found that the real part of the permittivity of the p-CNT film in the terahertz range is rather competitive, i.e. 8-13, however the loss tangent is not so small (0.4-0.6) as has been predicted. The way to increase p-CNT terahertz performance is also discussed.

Annual and seasonal patterns in etiologies of pediatric community-acquired pneumonia due to respiratory viruses and Mycoplasma pneumoniae requiring hospitalization in South Korea.

BACKGROUND: Community-acquired pneumonia (CAP) is one of the leading worldwide causes of childhood morbidity and mortality. Its disease burden varies by age and etiology and is time dependent. We aimed to investigate the annual and seasonal patterns in etiologies of pediatric CAP requiring hospitalization. METHODS: We conducted a retrospective study in 30,994 children (aged 0-18 years) with CAP between 2010 and 2015 at 23 nationwide hospitals in South Korea. Mycoplasma pneumoniae (MP) pneumonia was clinically classified as macrolide-sensitive MP, macrolide-less effective MP (MLEP), and macrolide-refractory MP (MRMP) based on fever duration after initiation of macrolide treatment, regardless of the results of in vitro macrolide sensitivity tests. RESULTS: MP and respiratory syncytial virus (RSV) were the two most commonly identified pathogens of CAP. With the two epidemics of MP pneumonia (2011 and 2015), the rates of clinical MLEP and MRMP pneumonia showed increasing trends of 36.4% of the total MP pneumonia. In children < 2 years of age, RSV (34.0%) was the most common cause of CAP, followed by MP (9.4%); however, MP was the most common cause of CAP in children aged 2-18 years of age (45.3%). Systemic corticosteroid was most commonly administered for MP pneumonia. The rate of hospitalization in intensive care units was the highest for RSV pneumonia, and ventilator care was most commonly needed in cases of adenovirus pneumonia. CONCLUSIONS: The present study provides fundamental data to establish public health policies to decrease the disease burden due to CAP and improve pediatric health.

Micelle-Assisted Formation of Nanoparticle Superlattices and Thermally Reversible Symmetry Transitions.

Nanoparticle superlattices (NPSLs) are of great interest as materials with designed emerging properties depending on the lattice symmetry as well as composition. The symmetry transition of NPSLs depending on environmental conditions can be an excellent ground for making new stimuli-responsive functional materials. Here, we report a spherical micelle-assisted method to form exceptionally ordered NPSLs which are inherently sensitive to environmental conditions. Upon mixing functionalized gold nanoparticles (AuNPs) with a nonionic surfactant spherical micellar solution, NPSLs of different symmetries such as NaZn13, MgZn2, and AlB2-type are formed depending on the size ratio between micelles and functionalized AuNPs and composition. The NPSLs formed by the spherical micelle-assisted method show thermally reversible order-order (NaZn13-AlB2) and order-disorder (MgZn2-isotropic) symmetry transitions, which are consistent with the Gibbs free energy calculations for binary hard-sphere model. This approach may open up new possibilities for NPSLs as stimuli-responsive functional materials.

Anisotropic interaction driven surface modulation on spray-dried microgranules.

Rapid evaporation of solvent from spray colloidal droplets induces directed self-assembly among the nanoparticles, eventually interlocking them into correlated granular structures. In this work, it is demonstrated that anisotropy in colloidal interparticle interaction plays a key role in governing the surface topology of spray-dried granules. Colloidal dispersion comprised of spherical nanosilica (NS) and cylindrical carbon nanotubes (CNT) was chosen as a model system in this regard. For identical polarities of the colloidal components, granules with prominent wrinkle-like modulations are obtained, which is in drastic contrast with the case of opposite polarities. The extent of surface modulation depends on the relative concentration of CNT with respective to NS. A plausible mechanism for the formation of surface modulation is elucidated on the basis of the evolving anisotropic interparticle interactions during assembly. Electron microscopy, small-angle scattering, Raman spectroscopic techniques have been used for quantitative characterization of these micro-granules.

Multifunctional effects of a modification of SLA titanium implant surface with strontium-containing nanostructures on immunoinflammatory and osteogenic cell function.

This study investigated the effects of surface modification of clinically available sandblasted/acid-etched (SLA) titanium oral implants with strontium (Sr)-containing nanostructures on both early immunoinflammatory macrophage cell functions and osteogenic stem cell functions. The goal was to provide insight for future surface engineering of titanium implants with multifunctional effects, that is, tissue healing capacity at both the nonosteogenic cell centered initial stage and the subsequent osteogenic cell-governed later stage-osseointegration process. The Sr-containing nanostructure was prepared in on the SLA-type implant surface by wet chemical treatment. The results showed that Sr modification is favorable for early macrophage cell functions and increases osteogenic capacity of the SLA surface. Surface Sr modification notably upregulated regenerative macrophage phenotype expression and anti-inflammatory cytokine IL10 production while suppressing inflammatory cytokine TNFα. Sr incorporation enhanced certain early cellular events of ST2 stem cells such as early cellular spreading and critical integrin gene expression, which in turn notably increased osteogenic differentiation (osteogenesis-related phenotype gene expression and osteocalcin production) when combined with the microstructured SLA implant surface. Surface modification of SLA-type implants with Sr-containing nanostructures demonstrated the ability to favorably influence early immunoinflammatory macrophage cell functions and the functionality of osteogenesis cells, resulting in an enhanced osseointegration outcome. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 3009-3020, 2018.

Porous Silica-Coated Gold Sponges with High Thermal and Catalytic Stability.

A method to fabricate porous silica-coated Au sponges that show high thermal and catalytic stability has been developed for the first time. The method involves dense surface functionalization of Au sponges (made by self-assembly of Au nanoparticles) with thiolated poly(ethylene glycol) (SH-PEG), which provides binding and condensation sites for silica precursors. The silica coating thickness can be controlled by using SH-PEG of different molecular weights. The silica-coated Au sponge prepared by using 5 kDa SH-PEG maintains its morphology at temperature as high as 700 °C. The calcination removes all organic molecules, resulting in porous silica-coated Au sponges, which contain hierarchically connected micro- and mesopores. The hierarchical pore structures provide an efficient pathway for reactant molecules to access the surface of Au sponges. The porous silica-coated Au sponges show an excellent catalytic recyclability, maintaining the catalytic conversion percentage of 4-nitrophenol by NaBH4 to 4-aminophenol as high as 93% even after 10 catalytic cycles. The method may be applicable for other porous metals, which are of great interests for catalyst, fuel cell, and sensor applications.

Spontaneous hybrids of graphene and carbon nanotube arrays at the liquid-gas interface for Li-ion battery anodes.

We demonstrate that hybrid structures of graphene and single-walled carbon nanotubes (SWNTs) are precisely controlled at the liquid-gas interface. The functionalized SWNT Langmuir monolayers anchor single-layer graphene nanosheets (GNSs) suspended in water via Coulomb interaction at the interface. This GNS/SWNT hybrid multilayer electrode can be a promising anode material for Li-ion batteries, offering high specific capacity, outstanding power capability, and excellent cyclability.

In Vitro-In Vivo Correlation Using In Silico Modeling of Physiological Properties, Metabolites, and Intestinal Metabolism.

BACKGROUND: Recently, pharmaceutical research has focused on in vitro-in vivo correlation as a novel challenge, and in silico modeling has been an important component. As in silico models are highly representative of practical use, regulatory agencies such as the US Food and Drug Administration and European Medicines Agency have recognized and utilized in silico modeling as a useful tool; this allows pharmaceutical organizations to use Physiologically Based Pharmacokinetic (PBPK) models for decision-making, which may aid the financial efficiency of a clinical trial. However, some studies have shown differences of up to approximately 40% in pharmacokinetic parameters such as area under the curve or maximum serum concentration between observed and simulated data. METHODS: Gastroplus™ was used to demonstrate current PBPK simulation. 46 research papers were compared with each other's applications of PBPK simulation. RESULTS: To improve the accuracy of simulation, additional factors may need to be considered, such as precise volume of gastrointestinal sections, specific metabolism of the target drug, and physicochemical data of drug metabolites. Furthermore, the results of these simulations would be extremely valuable to the relevant applications. Simulation programs using Advanced Compartmental Absorption and Transit (ACAT)/PBPK modeling could be a powerful tool for companies performing pre-clinical experiments, and could provide a solution for the ethical issues and economic constraints of clinical trials. CONCLUSION: If in silico modeling produced more precise results that could closely match clinical data, it could be more readily used to screen drug pharmacodynamics in bodily systems, and the efficiency of clinical trials would be improved. However, simulation programs are currently limited in their accuracy of pharmacodynamic predictions. In developing new drugs, pharmaceutical companies should address this issue in order to improve in silico/PBPK modeling in the future.

Hierarchically self-assembled hexagonal honeycomb and kagome superlattices of binary 1D colloids.

Synthesis of binary nanoparticle superlattices has attracted attention for a broad spectrum of potential applications. However, this has remained challenging for one-dimensional nanoparticle systems. In this study, we investigate the packing behavior of one-dimensional nanoparticles of different diameters into a hexagonally packed cylindrical micellar system and demonstrate that binary one-dimensional nanoparticle superlattices of two different symmetries can be obtained by tuning particle diameter and mixing ratios. The hexagonal arrays of one-dimensional nanoparticles are embedded in the honeycomb lattices (for AB2 type) or kagome lattices (for AB3 type) of micellar cylinders. The maximization of free volume entropy is considered as the main driving force for the formation of superlattices, which is well supported by our theoretical free energy calculations. Our approach provides a route for fabricating binary one-dimensional nanoparticle superlattices and may be applicable for inorganic one-dimensional nanoparticle systems.Binary mixtures of 1D particles are rarely observed to cooperatively self-assemble into binary superlattices, as the particle types separate into phases. Here, the authors design a system that avoids phase separation, obtaining binary superlattices with different symmetries by simply tuning the particle diameter and mixture composition.

Green Synthesis of High-Purity Mesoporous Gold Sponges Using Self-Assembly of Gold Nanoparticles Induced by Thiolated Poly(ethylene glycol).

A facile and green synthesis method for mesoporous gold sponges has been developed, which involves a simple mixing of a very small amount of thiolated-poly(ethylene glycol) (SH-PEG) and citrate-covered gold nanoparticles (Au NPs) in aqueous solution at room temperature. While SH-PEG molecules have been widely used as biocompatible hydrophilic capping agents for Au NPs for stable dispersion in aqueous solution, here they are used as destabilizing agents. When SH-PEG molecules are mixed with citrate-covered Au NPs at the molar ratio ranging from 3 to 20 (SH-PEG/Au NP), mesoporous gold sponges with randomly interconnected 3D network structures are formed within 2 to 3 h. This is driven by the destabilization of negatively charged citrate molecules on Au NPs by a small number of SH-PEG molecules bonded on the particle surface, which results in the decrease in zeta potential and thus the assembly of Au NPs into porous sponges. The use of very low concentration of SH-PEG (ca. 20-200 nM) in aqueous solution at room temperature makes the method highly eco-friendly as well as results in high-purity as-synthesized gold sponges (98.7 wt %). The mesoporous gold sponges fabricated with the present method exhibit a high SERS activity, making them highly applicable for sensitive SERS detection of molecules.

Selective distributions of functionalized single-walled carbon nanotubes in a polymeric reverse hexagonal phase.

We have investigated the distributions of individually isolated and hydrophilically functionalized single-walled carbon nanotubes (p-SWNTs) in the Pluronic L121-water system at the reverse hexagonal phase using small-angle X-ray scattering (SAXS) and contrast-matched small-angle neutron scattering (SANS) measurements. As the p-SWNT-L121-water system is transitioned from the lamellar phase to the reverse hexagonal phase with temperature, p-SWNTs which were selectively distributed in the polar layers of the lamellar structure become selectively distributed in the cylindrical polar cores of the reverse hexagonal structure, forming a hexagonal array of p-SWNTs. This was clearly confirmed by the contrast-matched SANS measurements. The selective distribution of p-SWNTs in the reverse hexagonal phase is driven by the selective affinity of p-SWNTs to the polar domains of the block copolymer system. The method demonstrated in this study provides a new route for fabricating ordered SWNT superstructures and may be applicable for inorganic 1D nanoparticles such as semiconducting, metallic and magnetic nanorods which are of great interest.

Isolation of Legionella pneumophila from cooling towers, public baths, hospitals, and fountains in Seoul, Korea, from 2010 to 2012.

Legionnaire's disease is associated with a high mortality rate. The authors collected 3,495 water samples in Seoul, Korea, between 2010 and 2012 from public facilities (cooling towers, public baths, hospitals, and decorative fountains), which are considered the major habitats of Legionella pneumophila. In all, 527 (15.1%) isolates of L. pneumophila were obtained by microbial culture and polymerase chain reaction. Serological diagnosis and pulsed-field gel electrophoresis (PFGE) analysis were performed for the samples. The authors categorized the samples into four groups (A-D) on the basis of PFGE results. The analysis revealed that cooling towers containing the most samples with L. pneumophila serogroup 1 constituted the highest proportion of isolate. Samples from public facilities and serogroups could be distinctively classified by PFGE patterns. Thus, it is expected that source-specific features revealed through PFGE and serological analyses could serve as the basis for effectively coping with future outbreaks of L. pneumophila.

Highly ordered and highly aligned two-dimensional binary superlattice of a SWNT/cylindrical-micellar system.

We report a highly ordered intercalated hexagonal binary superlattice of hydrophilically functionalized single-walled carbon nanotubes (p-SWNTs) and surfactant (C12 E5 ) cylindrical micelles. When p-SWNTs (with a diameter slightly larger than that of the C12 E5 cylinders) were added to the hexagonally packed C12 E5 cylindrical-micellar system, p-SWNTs positioned themselves in such a way that the free-volume entropies for both p-SWNTs and C12 E5 cylinders were maximized, thus resulting in the intercalated hexagonal binary superlattice. In this binary superlattice, a hexagonal array of p-SWNTs is embedded in a honeycomb lattice of C12 E5 cylinders. The intercalated hexagonal binary superlattice can be highly aligned in one direction by an oscillatory shear field and remains aligned after the shear is removed.