In-Situ Formed Type I Nanocrystalline Perovskite Film for Highly Efficient Light-Emitting Diode.

Excellent color purity with a tunable band gap renders organic-inorganic halide perovskite highly capable of performing as light-emitting diodes (LEDs). Perovskite nanocrystals show a photoluminescence quantum yield exceeding 90%, which, however, decreases to lower than 20% upon formation of a thin film. The limited photoluminescence quantum yield of a perovskite thin film has been a formidable obstacle for development of highly efficient perovskite LEDs. Here, we report a method for highly luminescent MAPbBr3 (MA = CH3NH3) nanocrystals formed in situ in a thin film based on nonstoichiometric adduct and solvent-vacuum drying approaches. Excess MABr with respect to PbBr2 in precursor solution plays a critical role in inhibiting crystal growth of MAPbBr3, thereby forming nanocrystals and creating type I band alignment with core MAPbBr3 by embedding MAPbBr3 nanocrystals in the unreacted wider band gap MABr. A solvent-vacuum drying process was developed to preserve nanocrystals in the film, which realizes a fast photoluminescence lifetime of 3.9 ns along with negligible trapping processes. Based on a highly luminescent nanocrystalline MAPbBr3 thin film, a highly efficient green LED with a maximum external quantum efficiency of 8.21% and a current efficiency of 34.46 cd/A was demonstrated.

Long-term stable stacked CsPbBr3 quantum dot films for highly efficient white light generation in LEDs.

We report highly efficient ethyl cellulose with CsPbBr3 perovskite QD films for white light generation in LED application. Ethyl cellulose with CsPbBr3 quantum dots is applied with Sr2Si5N8 : Eu2+ red phosphor on an InGaN blue chip, achieving a highly efficient luminous efficacy of 67.93 lm W-1 under 20 mA current.

High power laser-driven ceramic phosphor plate for outstanding efficient white light conversion in application of automotive lighting.

We report on Y3Al5O12: Ce(3+) ceramic phosphor plate (CPP) using nano phosphor for high power laser diode (LD) application for white light in automotive lighting. The prepared CPP shows improved luminous properties as a function of Ce(3+) concentration. The luminous properties of the Y3Al5O12: Ce(3+) CPP nano phosphor are improved when compared to the Y3Al5O12: Ce(3+) CPP with bulk phosphor, and hence, the luminous emittance, luminous flux, and conversion efficiency are improved. The Y3Al5O12: Ce(3+) CPP with an optimal Ce(3+) content of 0.5 mol % shows 2733 lm/mm(2) value under high power blue radiant flux density of 19.1 W/mm(2). The results indicate that Y3Al5O12: Ce(3+) CPP using nano phosphor can serve as a potential material for solid-state laser lighting in automotive applications.

Parental artistic drawings of the fetus before and after 3-/4-dimensional ultrasonography.

OBJECTIVE: The purpose of this study was to assess the impact of 3-/4-dimensional ultrasonography (3D/4DUS) on parental impressions of their fetus using preexamination and postexamination parental drawings. METHODS: One hundred one parents (32 male and 69 female) were asked to draw pictures of their fetus immediately before and after undergoing 3D/4DUS. A drawing assessment instrument was used to evaluate the fetal anatomy by 4 reviewers. Overall descriptive quality and a comparison of before and after images were assessed. RESULTS: Reviewers judged the drawings as significantly different in 23% to 56% of cases, slightly different in 41% to 64%, and having no significant difference in 2% to 22%; some difference was identified in at least 78%. Reviewers familiar with ultrasonography were able to correctly predict which picture was drawn first in 78%. Differences identified were related to extremity positioning, personalized uterine environment, and artistic nature. No significant difference in the overall total scoring for anatomic differentiation before and after 3D/4DUS was found. A trend in drawing less anatomic structures after 3D/4DUS was discovered. Significantly fewer people drew hair after 3D/4DUS (P<.01) even when they had drawn hair before the 3D/4DUS. Similar significant differences were seen for the lower extremities (P<.01), with less detail being presented after the 3D/4DUS. CONCLUSIONS: Differences were seen between drawings made before and after 3D/4DUS by parents. Drawings after 3D/4DUS emphasized structures seen during the 3D/4DUS examination and were more reality based, whereas drawings before 3D/4DUS were more iconographic and based on preconceived anatomic knowledge.

Preexamination and postexamination assessment of parental-fetal bonding in patients undergoing 3-/4-dimensional obstetric ultrasonography.

OBJECTIVE: The purpose of this study was to determine whether there is a change in parental bonding and couples' attitudes toward their fetus after undergoing 3-/4-dimensional ultrasonography (3D/4DUS). METHODS: Sixty-five fathers and 124 mothers were asked to fill out a maternal-fetal attachment questionnaire relating to how they felt about their fetus before and after 3D/4DUS and to mark on a line indicating their feelings about the ultrasonography experience. In addition, 135 parents filled out a positive feelings questionnaire consisting of 5 sections assessing their feelings about the fetus. The 3D/4DUS examination included rendering of the fetal face, limbs, and thorax. RESULTS: One hundred forty-two patients filled out all questions and were analyzed for the total attachment score. The difference of the total score for the maternal-fetal attachment questionnaire before and after 3D/4DUS had a z value of 5.6 for all patients and was statistically significant (P < .0001). In analyzing each question, 5 were found to have a statistically significantly different score for women, but only 2 were found so for men. The scores for the line, before and after 3D/4DUS, showed a significant difference for men but not women. The women studied did not show a change using this instrument because their median response was at the maximum measurement before their sonograms. The positive feelings questionnaire showed a statistically significant change for women in all sections but for men in only 2. CONCLUSIONS: Parents have a change in attitude regarding their fetus after undergoing 3D/4DUS. Mothers showed an increase in bonding to their fetus after 3D/4DUS in more categories than fathers.

Isolated echogenic foci in the left upper quadrant of the fetal abdomen: are they significant?

OBJECTIVES: To evaluate fetuses with echogenic foci in the left upper quadrant of the abdomen by sonographic examination. METHODS: Between November 2000 and October 2001, we prospectively assessed fetuses with echogenic foci in the abdominal left upper quadrant on routine prenatal sonography. The location, number, and size of the foci were analyzed, and in utero and postpartum follow-up scans were performed. A pediatrician evaluated the perinatal outcome. RESULTS: Twenty-six fetuses had 35 echogenic foci in the left upper quadrant of the abdomen at gestational ages of 20 to 37 weeks. The locations of the foci along the stomach, spleen, and the left lobe of the liver were found on sonography and measured 2 to 5 mm. Of the 16 fetuses who had follow-up scans in utero, 7 had disappearance of the foci. Postpartum follow-up scans were performed in 12 cases. Among them, 9 neonates had no lesions, and 3 had echogenic foci of a size and appearance similar to those seen prenatally in the left lobe of the liver. Only 1 of 4 patients who had TORCH (toxoplasmosis, other, rubella, cytomegalovirus, and herpes simplex) titers evaluated had elevated immunoglobulin G levels; no patient had any sign of infection after birth. All fetuses had a normal postnatal outcome. CONCLUSIONS: Many echogenic foci in the left upper quadrant of the fetal abdomen will disappear, and the outcome is promising even when the lesion persists after birth.

Gender differences in the corpus callosum of neonates.

The gender difference of corpus callosum is a long standing controversy. Some investigators have reported that adult females have a more bulbous splenium and larger area relative to brain size, but others failed to replicate this. Few studies have reported on sexual dimorphism during development. Midsagittal ultrasonographs were obtained through the anterior fontanelle of healthy Korean neonates (100 males, 100 females) and were analyzed with NIH Image. The total area of corpus callosum and sub-regions of corpus callosum showed no gender differences. However, the male corpus callosum had significantly more height than that of the female whereas there was no difference in width of the corpus callosum. The estimated average thickness of corpus callosum was greater in the female splenium.