Vehicle Load Estimation Using the Reaction Force of a Vertical Displacement Sensor Based on Fiber Bragg Grating.

Accurately calculating the vehicle load acting on a bridge at any one time is crucial to determining the integrity and safety of the bridge. To ensure this integrity and safety, information on the types, characteristics, and load of vehicles that regularly cross the bridge is very important in terms of its structural adequacy and maintenance. In this study, the vehicle load that a bridge will be subjected to was estimated using the reaction force response at the support. To estimate this response to the reaction force, a vertical displacement sensor, developed based on Fiber Bragg Grating (FBG), was applied to the Eradi Quake System (EQS), a commercially available bridge bearing. This vertical displacement sensor can measure the vertical load and has the advantage of being easy to attach and detach. To verify the performance and accuracy of this sensor, this study conducted numerical analysis and vehicle loading tests. It found that the vehicle load can be estimated from the reaction force response, as measured by the vertical displacement sensor on the bridge.

Non-Contact Water Level Response Measurement of a Tubular Level Gauge Using Image Signals.

The occurrence of excessive fluid sloshing during an earthquake can damage structures used to store fluids and can induce secondary disasters, such as environmental destruction and human casualties, due to discharge of the stored fluids. Thus, to prevent such disasters, it is important to accurately predict the sloshing behavior of liquid storage tanks. Tubular level gauges, which visually show the fluid level of a liquid storage tank, are easy to install and economical compared to other water level gauges. They directly show the fluid level and can be applied for various fluids because they can be constructed with various materials according to the fluid characteristics and the intended use. Therefore, in this study, the shaking table test was conducted to verify the validity of the method for measuring the water level response of the tubular level gauge installed on a liquid storage tank using image signals. In addition, image enhancement methods were applied to distinguish between the float installed in the tubular level gauge and the gray level of the background.

Chiral templating of self-assembling nanostructures by circularly polarized light.

The high optical and chemical activity of nanoparticles (NPs) signifies the possibility of converting the spin angular momenta of photons into structural changes in matter. Here, we demonstrate that illumination of dispersions of racemic CdTe NPs with right- (left-)handed circularly polarized light (CPL) induces the formation of right- (left-)handed twisted nanoribbons with an enantiomeric excess exceeding 30%, which is ∼10 times higher than that of typical CPL-induced reactions. Linearly polarized light or dark conditions led instead to straight nanoribbons. CPL 'templating' of NP assemblies is based on the enantio-selective photoactivation of chiral NPs and clusters, followed by their photooxidation and self-assembly into nanoribbons with specific helicity as a result of chirality-sensitive interactions between the NPs. The ability of NPs to retain the polarization information of incident photons should open pathways for the synthesis of chiral photonic materials and allow a better understanding of the origins of biomolecular homochirality.

Enzymatic formation of carbohydrate rings catalyzed by single-walled carbon nanotubes.

Macrocyclic carbohydrate rings were formed via enzymatic reactions around single-walled carbon nanotubes (SWNTs) as a catalyst. Cyclodextrin glucanotransferase, starch substrate and SWNTs were reacted in buffer solution to yield cyclodextrin (CD) rings wrapped around individual SWNTs. Atomic force microscopy showed the resulting complexes to be rings of 12-50 nm in diameter, which were highly soluble and dispersed in aqueous solution. They were further characterized by Raman and Fourier transform infrared spectroscopy and molecular simulation using density functional theory calculation. In the absence of SWNT, hydrogen bonding between glucose units determines the structure of maltose (the precursor of CD) and produces the curvature along the glucose chain. Wrapping SWNT along the short axis was preferred with curvature in the presence of SWNTs and with the hydrophobic interactions between the SWNTs and CD molecules. This synthetic approach may be useful for the functionalization of carbon nanotubes for development of nanostructures.

One-pot synthesis of multifunctional Au@graphene oxide nanocolloid core@shell nanoparticles for Raman bioimaging, photothermal, and photodynamic therapy.

The paper reports a facile one-pot synthesis of core@shell nanoparticles (NPs) composed of Au core and graphene oxide nanocolloid (GON) shell. Unique properties of Au NPs and GON can be incorporated into a single nanohybrid structure to provide desirable functions for theranosis such as localized surface plasmon resonance, Raman scattering, amphiphilic surface, and photothermal conversion. Synthesis of Au@GON NPs is achieved by simple one-pot reaction in aqueous phase utilizing GON as a reducing and stabilizing agent without any additional reducing agent. The zinc phthalocyanine, a photosensitizer, loaded Au@GON NPs show excellent multifunctional properties for combinational treatment of photothermal and photodynamic therapy in addition to Raman bioimaging with low cytotoxicity.

Bio-inspired Hierarchical Nanowebs for Green Catalysis.

Bio-inspired 3D hierarchical nanowebs are fabricated using silicon micropillars, carbon nanotubes (CNT), and manganese oxide. The Si pillars act as artificial branches for growing CNTs and the secondary metal coating strengthens the structures. The simple but effective structure provides both chemical and mechanical stability to be used as a green catalyst for recycling waste polymers into raw materials.

In-vitro cytotoxicity assessment of carbon-nanodot-conjugated Fe-aminoclay (CD-FeAC) and its bio-imaging applications.

We have investigated the cytotoxic assay of Fe-aminoclay (FeAC) nanoparticles (NPs) and simultaneous imaging in HeLa cells by photoluminescent carbon nanodots (CD) conjugation. Non-cytotoxic, photostable, and CD NPs are conjugated with cationic FeAC NPs where CD NPs play a role in bio-imaging and FeAC NPs act as a substrate for CD conjugation and help to uptake of NPs into cancer cells due to positively charged surface of FeAC NPs in physiological media. As increase of CD-FeAC NPs loading in HeLa cell in vitro, it showed slight cytotoxicity at 1000 µg/mL but no cytotoxicity for normal cells up to concentration of 1000 µg/mL confirmed by two 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and neutral red (NR) assays, with further observations by 4',6-diamidino-2-phenylindole (DAPI) stained confocal microscopy images, possessing that CD-FeAC NPs can be used as potential drug delivery platforms in cancer cells with simultaneous imaging. Graphical abstract CD conjugation with organo-building blocks of delaminated FeAC NPs.

Hydrogen-induced morphotropic phase transformation of single-crystalline vanadium dioxide nanobeams.

We report a morphotropic phase transformation in vanadium dioxide (VO2) nanobeams annealed in a high-pressure hydrogen gas, which leads to the stabilization of metallic phases. Structural analyses show that the annealed VO2 nanobeams are hexagonal-close-packed structures with roughened surfaces at room temperature, unlike as-grown VO2 nanobeams with the monoclinic structure and with clean surfaces. Quantitative chemical examination reveals that the hydrogen significantly reduces oxygen in the nanobeams with characteristic nonlinear reduction kinetics which depend on the annealing time. Surprisingly, the work function and the electrical resistance of the reduced nanobeams follow a similar trend to the compositional variation due mainly to the oxygen-deficiency-related defects formed at the roughened surfaces. The electronic transport characteristics indicate that the reduced nanobeams are metallic over a large range of temperatures (room temperature to 383 K). Our results demonstrate the interplay between oxygen deficiency and structural/electronic phase transitions, with implications for engineering electronic properties in vanadium oxide systems.

Probing the photothermally induced phase transitions in single-crystalline vanadium dioxide nanobeams.

Using Raman spectroscopy, we demonstrated photothermally induced crystallographic phase transitions of vanadium dioxide (VO2) nanobeams clamped to and free-standing on a substrate. Compared to the temperature-dependent Raman measurements, the laser-power-dependent Raman characteristics provide substantial evidence for the photothermal origin of the phase transitions of the VO2 nanobeams. The laser power necessary to cause phase transitions in the free-standing nanobeam was approximately eight times smaller than the laser power used in the substrate-clamped nanobeam. Our study will enhance the understanding of the complex phase transitions of strongly correlated oxides and thereby provide a foundation for engineering desirable properties in novel devices.

Surfactant size effect on surface-enhanced Raman scattering intensity from silver nanoparticles.

We report on the synthesis of two types of Ag nanoparticles (NPs) and the influence of adsorbed surfactant size on the NP surface for surface-enhanced Raman scattering (SERS) signals. Both particles were of similar size and morphology but were covered by surfactants of different sizes; one surfactant was sodium citrate (molecular weight: 258) and the other was sodium polyacrylate (molecular weight: 2100). For SERS measurement, 4-mecapobenzoic acid and 4-naphthalene thiol as Raman-active dyes were immobilized on the surface of each AgNP. The signals from Raman-active dyes on AgNPs covered with citrate displayed 10 times higher intensity than those from polyacrylate-stabilized AgNPs. Elemental analysis (EA) revealed that the average weight percentage of sulfur is 0.94 wt% and 0.12 wt% for citrate-stabilized and polyacrylate-stabilized AgNPs, respectively. The sulfur content difference was attributed to the size of the existing surfactant influencing the ligand exchange by steric hindrance and subsequently the amount of sulfur content of the particles. These experimental results suggest that the size of initial surfactant should be taken into account when synthesizing a metal particle for enhancing SERS signal.

Synthesis and assembly of colloidal particles with sticky dimples.

The preparation of anisotropic colloidal particles by a simple yet versatile temperature-controlled swelling process is described. The resulting polymeric particles feature a surface dimple, the size and shape of which were determined by the amount of oil captured in particles and the interfacial tension between the three phases: polystyrene (PS), decane, and the suspending medium. Following the removal of free or physically adsorbed surfactant from the swollen particles, hydrophobic dimples were produced upon evaporation of the oil phase. We demonstrate the spontaneous assembly of these 'dimpled particles' into dumbbell shapes or trimers through a site-selective hydrophobic interaction.

Thermally modulated multilayered graphene oxide for hydrogen storage.

We have obtained high pressure H(2) isotherms with respect to the interlayer distance of multilayered graphene oxide (GO) modulated by thermal annealing. The maximum storage capacity is 4.8 (0.5) wt% at 77 K (298 K) and at 9.0 MPa pressure. We found the optimum GO interlayer distance for maximum H(2) uptake at 6.5 Å, similar to the predicted distances from first-principles calculations for graphite materials. Our results reveal that multilayered GO can be a practical material of choice to allow the use of graphene as a hydrogen storage material, provided that only small amounts of O and OH functional groups exist as spacers on GO sheets.

Multimodal Encapsulation to Selectively Permeate Hydrogen and Engineer Channel Conduction for p-Type SnOx Thin-Film Transistor Applications.

It has been challenging to synthesize p-type SnOx (1 < x < 2) and engineer the electrical properties such as carrier density and mobility due to the narrow processing window and the localized oxygen 2p orbitals near the valence band. Herein, we report on the multifunctional encapsulation of p-SnOx to limit the surface adsorption of oxygen and selectively permeate hydrogen into the p-SnOx channel for thin-film transistor (TFT) applications. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) measurements identified that ultrathin SiO2 as a multifunctional encapsulation layer effectively suppressed the oxygen adsorption on the back channel surface of p-SnOx and selectively diffused hydrogen across the entire thickness of the channel. Encapsulated p-SnOx-based TFTs demonstrated much enhanced channel conductance modulation in response to the gate bias applied, featuring higher on-state current and lower off-state current (on/off ratio > 103), field effect mobility of 3.41 cm2/(V s), and threshold voltages of ∼5-10 V. The fabricated devices show minimal deviations as small as ±6% in the TFT performance parameters, which demonstrates good reproducibility of the fabrication process. The relevance between the TFT performance and the effects of hydrogen permeation is discussed in regard to the intrinsic and extrinsic doping mechanisms. Density functional theory calculations reveal that hydrogen-related impurity complexes are in charge of the enhanced channel conductance with gate biases, which further supports the selective permeation of hydrogen through a thin SiO2 encapsulation.

Touchable 3D hierarchically structured polyaniline nanoweb for capture and detection of pathogenic bacteria.

A bacteria-capturing platform is a critical function of accurate, quantitative, and sensitive identification of bacterial pathogens for potential usage in the detection of foodborne diseases. Despite the development of various nanostructures and their surface chemical modification strategies, relative to the principal physical contact propagation of bacterial infections, mechanically robust and nanostructured platforms that are available to capture bacteria remain a significant problem. Here, a three-dimensional (3D) hierarchically structured polyaniline nanoweb film is developed for the efficient capture of bacterial pathogens by hand-touching. This unique nanostructure ensures sufficient mechanical resistance when exposed to compression and shear forces and facilitates the 3D interfacial interactions between bacterial extracellular organelles and polyaniline surfaces. The bacterial pathogens (Escherichia coli O157:H7, Salmonella enteritidis, and Staphylococcus aureus) are efficiently captured through finger-touching, as verified by the polymerase chain reaction (PCR) analysis. Moreover, the real-time PCR results of finger-touched cells on a 3D nanoweb film show a highly sensitive detection of bacteria, which is similar to those of the real-time PCR using cultured cells without the capturing step without any interfering of fluorescence signal and structural deformation during thermal cycling.

A facile hydrothermal synthesis of highly luminescent NaYF4:Yb3+/Er3+ upconversion nanoparticles and their biomonitoring capability.

Using a facile hydrothermal procedure, hydrophilic NaYF4: Yb3+/Er3+ nanoparticles (NPs) have been prepared as lanthanide-doped upconversion (UC) materials exhibiting different morphologies, crystal phases and luminescence intensity. The upconversion nanoparticles (UCNP) were characterized by means of electron microscopy and spectroscopy, X-ray diffraction (XRD) and photoluminescence analysis. The molar concentration of reactants and volumes of NaF affect the shapes and uniformity of the synthesized NPs. These parameters also have influence on crystal phase and luminescence intensity of the NPs. Adjusting hydrothermal reaction time and dopant concentration also enable the synthesis of NPs with strong UC luminescence. The as-prepared UCNP showed cellular nontoxicity to HeLa cells, and thus they are capable as promising agents for biological imaging.

Morphological evolution of upconversion nanoparticles and their biomedical signal generation.

Advancements in the fabrication of upconversion nanoparticles (UCNPs) for synthetic control can enable a broad range of applications in biomedical systems. Herein, we experimentally verified the role of the hydrothermal reaction (HR) time in the synthesis of NaYF4:20%Yb3+/3%Er3+ UCNPs on their morphological evolution and phase transformation at different temperatures. Characterizations of the as-prepared UCNPs were conducted using X-ray diffraction (XRD), electron microscopy and spectroscopy, and thermogravimetric and upconversion (UC) luminescence analysis. We demonstrated that determining the optimal HR time, also referred to here as the threshold time, can produce particles with good homogeneity, hexagonal phase, and UC luminescence efficiency. Subsequently, the polymer coated UCNPs maintained their original particle size distribution and luminescence properties, and showed improved dispersibility in a variety of solvents, cellular nontoxicity, in vitro bioimaging, and biocompatibility as compared to the bare UCNP. Besides this, polyacrylic acid conjugated UCNPs (UCNP@PAA) also revealed the strong anticancer effect by conjugating with doxorubicin (DOX) as compared to the free DOX. Based on these findings, we suggest that these particles will be useful in drug-delivery systems and as in vivo bioimaging agents synchronously.

Reducing Agent-Assisted Excessive Galvanic Replacement Mediated Seed-Mediated Synthesis of Porous Gold Nanoplates and Highly Efficient Gene-Thermo Cancer Therapy.

Porous Au nanoplates (pAuNPs) were manufactured by a reducing agent-assisted galvanic replacement reaction on Ag nanoplates using a seed-mediated synthetic approach. Two core additives, poly(vinylpyrrolidone) and l-ascorbic acid, prevented fragmentation and proceeded secondary growth. By controlling the concentration of the additives and the amount of replacing ion AuCl4-, various nanostructures including nanoplates with holes, nanoframes, porous nanoplates, and bumpy nanoparticles with unity and homogeneity were synthesized. The present synthetic method is advantageous, because it can be used to manufacture pAuNPs with ease, robustness, and convenience. The prepared pAuNPs exhibited a highly efficient photothermal conversion effect and cargo loading capacity on exposed surfaces by Au-thiol linkage. By using dual cargo mixed loading of the hepatitis C virus (HCV) targeting gene drug DNAzyme and cell-penetrating peptide TAT onto the surface of the pAuNPs and photothermal conversion-mediated hyperthermic treatment, successful gene-thermo therapy against HCV genomic human hepatocarcinoma cells were demonstrated.

Synthesis of upconversion nanoparticles conjugated with graphene oxide quantum dots and their use against cancer cell imaging and photodynamic therapy.

Multifunctional nanocomposite has a huge potential for cell imaging, drug delivery, and improving therapeutic effect with less side effects. To date, diverse approaches have been demonstrated to endow a single nanostructure with multifunctionality. Herein, we report the synthesis and application of core-shell nanoparticles composed with upconversion nanoparticle (UCNP) as a core and a graphene oxide quantum dot (GOQD) as a shell. The UCNP was prepared and applied for imaging-guided analyses of upconversion luminescence. GOQD was prepared and employed as promising drug delivery vehicles to improve anti-tumor therapy effect in this study. Unique properties of UCNPs and GOQDs were incorporated into a single nanostructure to provide desirable functions for cell imaging and drug delivery. In addition, hypocrellin A (HA) was loaded on GOQDs for photo-dynamic therapy (PDT). HA, a commonly used chemotherapy drug and a photo-sensitizer, was conjugated with GOQD by π-π interaction and loaded on PEGylated UCNP without complicated synthetic process, which can break structure of HA. Applying these core-shell nanoparticles to MTT assay, we demonstrated that the UCNPs with GOQD shell loaded with HA could be excellent candidates as multifunctional agents for cell imaging, drug delivery and cell therapy.

Surface-Modified Mesh Filter for Direct Nucleic Acid Extraction and its Application to Gene Expression Analysis.

Rapid and convenient isolation of nucleic acids (NAs) from cell lysate plays a key role for onsite gene expression analysis. Here, this study achieves one-step and efficient capture of NA directly from cell lysate by developing a cationic surface-modified mesh filter (SMF). By depositing cationic polymer via vapor-phase deposition process, strong charge interaction is introduced on the surface of the SMF to capture the negatively charged NAs. The NA capturing capability of SMF is confirmed by X-ray photoelectron spectroscopy, fluorescent microscopy, and zeta potential measurement. In addition, the genomic DNAs of Escherichia Coli O157:H7 can be extracted by the SMF from artificially infected food, and fluorescent signal is observed on the surface of SMF after amplification of target gene. The proposed SMF is able to provide a more simplified, convenient, and fast extraction method and can be applied to the fields of food safety testing, clinical diagnosis, or environmental pollutant monitoring.

Graphene growth from reduced graphene oxide by chemical vapour deposition: seeded growth accompanied by restoration.

Understanding the underlying mechanisms involved in graphene growth via chemical vapour deposition (CVD) is critical for precise control of the characteristics of graphene. Despite much effort, the actual processes behind graphene synthesis still remain to be elucidated in a large number of aspects. Herein, we report the evolution of graphene properties during in-plane growth of graphene from reduced graphene oxide (RGO) on copper (Cu) via methane CVD. While graphene is laterally grown from RGO flakes on Cu foils up to a few hundred nanometres during CVD process, it shows appreciable improvement in structural quality. The monotonous enhancement of the structural quality of the graphene with increasing length of the graphene growth from RGO suggests that seeded CVD growth of graphene from RGO on Cu surface is accompanied by the restoration of graphitic structure. The finding provides insight into graphene growth and defect reconstruction useful for the production of tailored carbon nanostructures with required properties.