Although the quantum efficiencies of quantum dots (QDs) are approaching unity through advances in the synthesis of QD materials, their luminescence efficiencies after mixing with resin and thermal curing for white light-emitting diodes (LEDs) are seriously lowered because of aggregation and oxidation of QDs and poor adhesion of QDs to the resin. To overcome these problems, QD-layer-encapsulated and phenyl-functionalized silica (SQS(Ph)) spheres were synthesized and applied for white LEDs, whereby the QDs were homogeneously distributed at radial equidistance from the center and near the surface of approximately 100 nm-sized silica spheres and the surface was functionalized with phenylethyl groups. The inter-core distances of QDs were over ∼14 nm, which is over the limit (<10 nm) for Förster resonance energy transfer (FRET) that leads to photoluminescence (PL) reduction. This hierarchical nanostructure excludes a chance of FRET between QDs and provides the QDs a gradually refractive index matching environment, which yields ∼4-fold enhanced PL in SQS(Ph). More importantly, the SQS(Ph) acquired a highly adhesive property to silicone resin due to their phenyl functional group matching, which resulted in remarkably improved light extraction in white LEDs. When incorporated along with a yellow-emitting Y3Al5O12:Ce(3+) (YAG:Ce) phosphor and silicone resin on blue LED chips, the SQS(Ph) spheres presented significantly improved performance [luminous efficiency (LE) = 58.2 lm W(-1); colour rendering index Ra = 81.8; I/I0 = 0.98 after 60 h operation] than their original QDs (LE = 39.6 lm W(-1); Ra = 78.1; I/I0 = 0.91 after 60 h operation) under a forward bias current of 60 mA.

Commercial ELISA kits for substance P (SubP), which are helpful for the clinical diagnosis of acute myocardial infarction, are limited in efficacy because of low sensitivity. A highly sensitive immunoassay was developed using silica spheres encapsulating a quantum dot-layer (SQS) and labeling antibodies, on a Parylene A-modified plate. The high sensitivity was possible by taking advantage of the enhanced photoluminescence of the SQS and dense immobilization of SubP on a Parylene A-modified plate. Glutaraldehyde was used for cross-linking of SQS to the anti-SubP antibody and SubP to the Parylene A coating. The SQS-linked immunosorbent assay (SQSLISA) was optimized and validated. The dynamic range for the assay was 1-10000 pg/mL with a linear correlation factor of 0.9992 when the competitive SQSLISA was employed. The intra- and interday accuracies were 93-100% and 87-122%, respectively. The reproducibility was lower than 11%. The developed method was applied to clinical samples collected from healthy controls (n = 30) and acute myocardial infarction (n = 16) and it displayed a high correlation with the commercial ELISA kit, with a limit of detection that was 30-fold lower. Clinical sample analysis confirmed that SubP is a promising diagnostic marker for acute myocardial infarction. The SQSLISA is expected to be a practical and useful assay tool.

We present a novel, direct approach to hybridize hydrophobic quantum dot (QD) nanocrystals with colloidal silica (A) via van der Waals (vdW) force only. The A is constructed by aggregation of 15-25 nm sized hydrophobic silica nanoparticles with octadecyl groups. For hybridization, the hydrophobic QDs sit on the crevices of A via reinforced vdW force by interdigitation of long-chained hydrocarbons along the enlarged contact area of the crevices. The hybrids (B) are easily encapsulated with silica with/without functional groups, yielding QD-layer-incorporated silica particles (C) with greatly enhanced PL (up to 690%) and astonishing photostability compared with their free QDs under an identical QD concentration. This approach is simple, novel, versatile, and extended to the cases of three different sized QDs. The hydrophobic product C with phenylethyl groups is applicable to fabricate a white LED, and its hydrophilic analogues can be a promising material for bioapplications.

The present study examined the 2017 Times Higher Education annual rankings for Japanese institutions of higher learning. Based on the analytic model as mapped out previously using Canadian data, we offered a similar protocol for the top 100 institutions of higher education in Japan. Three analyses showed that: (a) overall rank correlated with individual index ranks for 9 of the 13 indices, (b) the schools appearing among the top institutions overall ranked significantly better on 8 of the 13 indices compared to schools appearing among the bottom institutions overall, and (c) schools were empirically grouped into four meaningful families or clusters whose constituent members shared a comparable profile of indices. We offer a juxtaposition of the present results to annual evaluations from Canada’s institutions of higher learning. The wider implications include an international comparison of institutions of higher learning, a proposed analysis protocol that Japanese education administrations may further pursue, and a categorical breakdown of educational institutions in Japan. Directions for future research are outlined.