The unique optical properties of metals are at the core of many areas of research and applications, including plasmonics, metamaterials, superlensing and subdiffraction focusing, optical antennas and ...surface enhanced Raman scattering. One important length scale inherent in metamaterials and plasmonics research activities in the microwave, terahertz, infrared, visible and ultraviolet ranges is the skin depth of metal, which remains at the submicrometre level throughout the broad spectral range. One prominent question is whether terahertz electromagnetic waves can be controlled on the nanoscale to achieve new functionalities in the sub-skin-depth regime. Here, we show that a λ/30,000 slit on metal film acts as a nanogap-capacitor charged by light-induced currents, enhancing the electric field by orders of magnitudes.
Pulp-dentin Regeneration Cao, Y.; Song, M.; Kim, E. ...
Journal of Dental Research,
11/2015, Volume:
94, Issue:
11
Book Review, Journal Article
Peer reviewed
The goal of regenerative endodontics is to reinstate normal pulp function in necrotic and infected teeth that would result in reestablishment of protective functions, including innate pulp immunity, ...pulp repair through mineralization, and pulp sensibility. In the unique microenvironment of the dental pulp, the triad of tissue engineering would require infection control, biomaterials, and stem cells. Although revascularization is successful in resolving apical periodontitis, multiple studies suggest that it alone does not support pulp-dentin regeneration. More recently, cell-based approaches in endodontic regeneration based on pulpal mesenchymal stem cells (MSCs) have demonstrated promising results in terms of pulp-dentin regeneration in vivo through autologous transplantation. Although pulpal regeneration requires the cell-based approach, several challenges in clinical translation must be overcome—including aging-associated phenotypic changes in pulpal MSCs, availability of tissue sources, and safety and regulation involved with expansion of MSCs in laboratories. Allotransplantation of MSCs may alleviate some of these obstacles, although the long-term stability of MSCs and efficacy in pulp-dentin regeneration demand further investigation. For an alternative source of MSCs, our laboratory developed induced MSCs (iMSCs) from primary human keratinocytes through epithelial-mesenchymal transition by modulating the epithelial plasticity genes. Initially, we showed that overexpression of ΔNp63α, a major isoform of the p63 gene, led to epithelial-mesenchymal transition and acquisition of stem characteristics. More recently, iMSCs were generated by transient knockdown of all p63 isoforms through siRNA, further simplifying the protocol and resolving the potential safety issues of viral vectors. These cells may be useful for patients who lack tissue sources for endogenous MSCs. Further research will elucidate the level of potency of these iMSCs and assess their transdifferentiation capacities into functional odontoblasts when transplanted into the root canal microenvironment.
Nano‐embossed hollow spherical (NeHS) TiO2 that features both good light scattering and charge generation shows a very promising performance in high‐efficiency dye‐sensitized solar cells. A bilayered ...film structure having the bifunctional NeHS TiO2 particulate film as an overlayer exhibits conversion efficiencies as high as 10.34 % under AM‐1.5G one sun light intensity.
Pulp capping, or placing dental materials directly onto the vital pulp tissues of affected teeth, is a dental procedure that aims to regenerate reparative dentin. Several pulp capping materials are ...clinically being used, and calcium ion (Ca2+) released from these materials is known to mediate reparative dentin formation. ORAI1 is an essential pore subunit of store-operated Ca2+ entry (SOCE), which is a major Ca2+ influx pathway in most nonexcitable cells. Here, we evaluated the role of ORAI1 in mediating the odontogenic differentiation and mineralization of dental pulp stem cells (DPSCs). During the odontogenic differentiation of DPSCs, the expression of ORAI1 increased in a time-dependent manner. DPSCs knocked down with ORAI1 shRNA (DPSC/ORAI1sh) or overexpressed with dominant negative mutant ORAI1E106Q (DPSC/E106Q) exhibited the inhibition of Ca2+ influx and suppression of odontogenic differentiation and mineralization as demonstrated by alkaline phosphatase (ALP) activity/staining as well as alizarin red S staining when compared with DPSCs of their respective control groups (DPSC/CTLsh and DPSC/CTL). The gene expression for odontogenic differentiation markers such as osteocalcin, bone sialoprotein, and dentin matrix protein 1 (DMP1) was also suppressed. When DPSC/CTL or DPSC/E106Q cells were subcutaneously transplanted into nude mice, DPSC/CTL cells induced mineralized tissue formation with significant increases in ALP and DMP1 staining in vivo, whereas DPSC/E106Q cells did not. Collectively, our data showed that ORAI1 plays critical roles in the odontogenic differentiation and mineralization of DPSCs by regulating Ca2+ influx and that ORAI1 may be a therapeutic target to enhance reparative dentin formation.
Bisphosphonate-related osteonecrosis of the jaw (BRONJ) commonly occurs in individuals receiving bisphosphonates (BPs) with clinical manifestations of the exposed necrotic bone. Although defective ...wound healing of soft tissue is frequently, if not always, observed in BRONJ, the effects of BPs on oral soft tissue or cells remain unknown. To investigate the effects of BPs on cells of oral mucosal tissue, we studied the effect of pamidronate (PAM), one of the BPs most commonly administered to cancer patients, on the phenotypes of normal human oral keratinocytes (NHOK) and fibroblasts (NHOF). When exposed to PAM at 10 µM, NHOK, not NHOF, underwent senescence: NHOK overexpressed senescence-associated β-galactosidase (SA-β-Gal), p16INK4A, IL-6, and IL-8. When exposed to a higher level (50 µM) of PAM, NHOK maintained senescent phenotypes, but NHOF underwent apoptosis. PAM-induced senescence in NHOK is mediated, in part, via geranylgeranylation of the mevalonate pathway. Our in vitro 3D oral mucosal tissue construction studies further demonstrated that PAM induced senescence and impaired re-epithelialization of oral mucosa. Analysis of these data indicates that premature senescence of oral mucosal cells and subsequent defective soft-tissue wound healing might be partly responsible for the development of BRONJ in individuals receiving PAM or other BPs.
Recently, Lee et al reported a new grading system for the lumbar spinal foraminal stenosis. They considered the type of stenosis, the amount of fat obliteration, and the presence of nerve root ...compression. Our aim was to evaluate whether a new MR imaging grading system correlated with symptoms and neurologic signs and could replace the previous grading system.
We examined 91 patients (M/F = 49:42; mean age, 50 years) who visited our institution and underwent MR imaging of the L-spine and were evaluated by 2 musculoskeletal radiologists. The presence and grade of lumbar foraminal stenosis at the maximal narrowing point was assessed according to the new grading system suggested by Lee et al (Lee system) and the Wildermuth grading system (Wildermuth system). Results were correlated with clinical manifestations and neurologic physical examination. Statistical analysis was performed by using κ statistics, categoric regression analysis, and nonparametric correlation analysis (Spearman correlation).
Interobserver agreement in the grading of foraminal stenosis between the 2 readers was substantially correlated (κ of Lee system = 0.767, κ of Wildermuth system = 0.734). The Rs for reader 1 and reader 2 between the Lee system and the Wildermuth system were 0.880 and 0.885, between Lee system and PNM were 0.715 and 0.604, and between the Wildermuth system and PNM were 0.800 and 0.680. For patients younger than 50 years of age, the R between the Lee and Wildermuth systems was higher than that for patients 50 years or older, but the Rs between the grading system and PNM were lower in the younger group than in the older group. The Rs of the Wildermuth system with PNM were higher in the older group than in the younger group; the differences between the Rs of the Lee system with PNM and the Wildermuth system with PNM were higher in the older group (0.016 young versus 0.130 old and 0.008 versus 0.107).
Interobserver agreement of the Lee system was slightly higher than the Wildermuth system and substantially correlated. Both systems are good for evaluation of lumbar spinal foraminal stenosis, but the Lee system showed slightly better interobserver agreement and good clinical correlation in the younger group of patients.
Cosmic-ray proton and helium spectra have been measured with the balloon-borne Cosmic Ray Energetics And Mass experiment flown for 42 days in Antarctica in the 2004-2005 austral summer season. ...High-energy cosmic-ray data were collected at an average altitude of ~38.5 km with an average atmospheric overburden of ~3.9 g cm--2. Individual elements are clearly separated with a charge resolution of ~0.15 e (in charge units) and ~0.2 e for protons and helium nuclei, respectively. The measured spectra at the top of the atmosphere are represented by power laws with a spectral index of --2.66 ? 0.02 for protons from 2.5 TeV to 250 TeV and --2.58 ? 0.02 for helium nuclei from 630 GeV nucleon--1 to 63 TeV nucleon--1. They are harder than previous measurements at a few tens of GeV nucleon--1. The helium flux is higher than that expected from the extrapolation of the power law fitted to the lower-energy data. The relative abundance of protons to helium nuclei is 9.1 ? 0.5 for the range from 2.5 TeV nucleon--1 to 63 TeV nucleon--1. This ratio is considerably smaller than the previous measurements at a few tens of GeV nucleon--1.
We present new measurements of the energy spectra of cosmic-ray (CR) nuclei from the second flight of the balloon-borne experiment Cosmic-Ray Energetics And Mass (CREAM). The instrument included ...different particle detectors to provide redundant charge identification and measure the energy of CRs up to several hundred TeV. The measured individual energy spectra of C, O, Ne, Mg, Si, and Fe are presented up to ~1014 eV. The spectral shape looks nearly the same for these primary elements and it can be fitted to an E -2.66 +/- 0.04 power law in energy. Moreover, a new measurement of the absolute intensity of nitrogen in the 100-800 GeV/n energy range with smaller errors than previous observations, clearly indicates a hardening of the spectrum at high energy. The relative abundance of N/O at the top of the atmosphere is measured to be 0.080 +/- 0.025 (stat.)+/-0.025 (sys.) at ~800 GeV/n, in good agreement with a recent result from the first CREAM flight.
CH3NH3PbI3 perovskite solar cells with a mesoporous TiO2 layer and spiro-MeOTAD as a hole transport layer (HTL) with three different CH3NH3I concentrations (0.032 M, 0.044 M and 0.063 M) were ...investigated. Strong variations in crystal size and morphology resulting in diversified cell efficiencies (9.2%, 16.9% and 12.3%, respectively) were observed. The physical origin of this behaviour was analysed by detailed characterization combining current-voltage curves with photo- and electroluminescence (PL and EL) imaging as well as light beam induced current measurements (LBIC). It was found that the most efficient cell shows the highest luminescence and the least efficient cell is most strongly limited by non-radiative recombination. Crystal size, morphology and distribution in the capping layer and in the porous scaffold strongly affect the non-radiative recombination. Moreover, the very non-uniform crystal structure with multiple facets, as evidenced by SEM images of the 0.032 M device, suggests the creation of a large number of grain boundaries and crystal dislocations. These defects give rise to increased trap-assisted non-radiative recombination as is confirmed by high-resolution μ-PL images. The different imaging techniques used in this study prove to be well-suited to spatially investigate and thus correlate the crystal morphology of the perovskite layer with the electrical and radiative properties of the solar cells and thus with their performance.
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