Single crystalline and nearly monodisperse In2O3 nanocrystals with both dot and flower shapes were synthesized in a simple reaction system. This system used indium carboxylates as the precursors with or without alcohol as the activating reagents in a hydrocarbon solvent under elevated temperatures. Limited ligand protection (LLP) led to three-dimensional (3D) oriented attachment of nanodots, resulting in 3D nanoflowers. When the system had sufficient ligand protection for the nanocrystals, nanodots were found to be the stable products. The diameters of nearly monodisperse nanodots and nanoflowers were varied in a range from approximately 5 to approximately 15 nm and approximately 15 to approximately 60 nm, respectively. The simple reaction system made it possible to have a systematic study of the reaction mechanisms along with the growth kinetics of nanocrystals. Hydrolysis and alcoholysis were identified as the major paths for this system, as opposed to pyrolysis. Both nearly monodispersed nanodots and nanoflowers can be made through either of the reaction pathways. Hydrolysis was found as a reversible pathway, and alcoholysis was confirmed to be irreversible. Consequently, a sufficient amount of alcohol was able to force the yield of nanocrystals, both dots and flowers, to unity.

Visual color changes between 300 and 510 K were observed in the photoluminescence (PL) of colloidal InP/ZnS core-shell nanocrystals. A subsequent study of PL spectra in the range 2-510 K and fitting the temperature dependent line shift and line width to theoretical models show that the dominant (dephasing) interaction is due to scattering by acoustic phonons of about 23 meV. Low temperature photoluminescence excitation measurements show that the excitonic band gap depends approximately inversely linearly on the quantum dot size d, which is distinctly weaker than the dependence predicted by current theories.

Colloidal nanocrystals with controlled size and shape play a key role in nanotechnology. [1][2][3] Organometallic [4][5][6] and related alternative (or so-called greener) [7][8][9][10] synthetic methods at elevated temperatures in non-aqueous solvents are the current mainstream strategies for producing high-quality nanocrystals. The ability to control the size and size distribution of nanodots using these strategies is reasonably well developed. Also, advances in the formation of 1D nanocrystals have recently been reported. [5,[11][12][13][14] These 1D structures offer a unique technical potential that is inaccessible with the corresponding 0D nanocrystals. Reports on the synthesis of complex 3D nanostructures, however, remain uncommon. [15][16][17][18][19] Most of these structures are grown on substrates, are large in size, and/or are polycrystalline. Herein, we demonstrate that, by simply reducing the degree of ligand protection to the domain of limited ligand protection (LLP), the existing mainstream synthetic chemistry for 0D and 1D nanocrystals-more specifically, the greener approaches-can also produce high-quality complex 3D nanostructures, such as crystalline nanoflowers. Unlike the formation of tetrapods of II-VI semiconductors with specific crystal structures, [15,20] we reveal that LLP coupled with 3D oriented attachment can be applied in the preparation of nanocrystals with different compositions, crystal structures, and physical (magnetic and electronic) properties.The LLP strategy was first applied to the In 2 O 3 nanocrystal system, and it was not clear if the 3D oriented attachment caused by LLP would be limited to certain crystal structures and compositions. Herein, we intend to clarify the generality of the LLP strategy. A detailed account of the nanocrystal growth mechanism will be reported separately. [21]

No abstract

Objective: To assess the diagnostic performance of angle measurements from anterior segment optical coherence tomography (AS-OCT) images for identifying eyes with narrow angles. Methods: We conducted a community-based crosssectional study of individuals 50 years or older who had phakic eyes and who underwent AS-OCT imaging in the dark by a single operator and gonioscopy by an ophthalmologist masked to AS-OCT findings. An eye was considered to have narrow angles if the posterior pigmented trabecular meshwork was not visible for at least 180°on gonioscopy. Horizontal AS-OCT images were analyzed for the following measurements using customized software: angle opening distance (AOD) at 250, 500, and 750 µm from the scleral spur; trabecular-iris space area (TISA) at 500 and 750 µm; and angle recess area (ARA) at 750 µm. Areas under the receiver operating characteristic curves (AUCs) were generated for AOD, TISA, and ARA to assess the performance of these measurements in detecting eyes with narrow angles. Results: Of 2047 individuals examined, 582 were excluded mostly because of poor image quality or inability to locate the scleral spur. Of the remaining 1465 participants, 315 (21.5%) had narrow angles on gonioscopy. Mean (SD) age was 62.7 (7.7) years, 54.1% were women, and 90.0% were Chinese. The AUCs were highest for AOD750 in the nasal (0.90 [95% confidence interval, 0.89-0.92]) and temporal (0.91 [0.90-0.93]) quadrants. Conclusions: The AOD750 is the most useful angle measurement for identifying individuals with gonioscopic narrow angles in gradable AS-OCT images. Poor definition of the scleral spur precludes quantitative analysis in approximately 25% of AS-OCT images.

No abstract

Colloidal InP/ZnS core-shell nanocrystals were prepared via a non-organometallic approach in a noncoordinating solvent. The energy shift and line broadening of the e 1 -h 1 (HOMO-LUMO) transition have been investigated using photoluminescence studies in the temperature range 300-525 K. The energy of the e 1 -h 1 transition decreases with increasing temperature due to the exciton-phonon interaction and has been fitted to phenomenological equations, from which the Huang-Rhys factor and the average phonon energy are extracted. The photoluminescence line width increases with temperature and is analyzed with respect to the standard equation describing the temperature dependence of the width of the lowest-lying exciton. The results show that, in the temperature range 300-525 K, the variation of both the energy band gap and the photoluminescence line broadening are predominantly due to coupling of the e 1 -h 1 transition to the acoustic phonons.

IMPORTANCE Glaucoma represents a major public health challenge in an aging population. The Tanjong Pagar Eye Study reported the prevalence and risk factors of glaucoma in a Singapore Chinese population in 1997, which established the higher rates of blindness in this population.OBJECTIVES To determine the prevalence and associated risk factors for glaucoma among Chinese adults in Singapore and to compare the results with those of the 1997 study. DESIGN, SETTING, AND PARTICIPANTS In a population-based survey of 4605 eligible individuals, we selected 3353 Chinese adults 40 years or older from the southwestern part of Singapore. Participants underwent examination at a single tertiary care research institute from February 9, 2009, through December 19, 2011. EXPOSURES All participants underwent slitlamp ophthalmic examination, applanation tonometry, measurement of central corneal thickness, gonioscopy, and a dilated fundus examination. MAIN OUTCOMES AND MEASURES Glaucoma as defined by the International Society of Geographical and Epidemiological Ophthalmology guidelines and age-standardized prevalence estimates computed as per the 2010 Singapore Chinese census. Blindness was defined as logMAR visual acuity of 1.00 (Snellen equivalent, 20/200 or worse).RESULTS Of the 3353 respondents, 134 (4.0%) had glaucoma, including primary open-angle glaucoma (POAG) in 57 (1.7%), primary angle-closure glaucoma (PACG) in 49 (1.5%), and secondary glaucoma in 28 (0.8%). The age-standardized prevalence (95% CI) of glaucoma was 3.2% (2.7%-3.9%); POAG, 1.4% (1.1%-1.9%); and PACG, 1.2% (0.9%-1.6%). In a multivariate model, POAG was associated with being older and male and having a higher intraocular pressure. Of the 134 participants with glaucoma, 114 (85.1%; 95% CI, 78.1%-90.1%) were not aware of their diagnosis. Prevalence (95% CI) of blindness caused by secondary glaucoma was 14.3% (5.7%-31.5%), followed by 10.2% (4.4%-21.8%) for PACG and 8.8% (3.8%-18.9%) for POAG. We could not identify a difference in the prevalence of glaucoma compared with the 3.2% reported in 1997 (difference, −0.04%; 95% CI, −1.2 to 1.2; P = .97). CONCLUSIONS AND RELEVANCEThe prevalence of glaucoma among Singapore Chinese likely ranges from 2.7% to 3.9%, with secondary glaucoma being the most visually debilitating type. We could not identify a difference compared with previous studies approximately 12 years earlier. We report a high proportion of previously undiagnosed disease, suggesting the need to increase public awareness of this potentially blinding condition.