Red green blue emissive lead sulfide quantum dots: heterogeneous synthesis and applications

Hou, Bo,Cho, Yuljae,Kim, Byung-Sung,Ahn, Docheon,Lee, Sanghyo,Park, Jong Bae,Lee, Young-Woo,Hong, John,Im, Hyunsik,Morris, Stephen M.,Sohn, Jung Inn,Cha, SeungNam,Kim, Jong Min Royal Society of Chemistry 2017 Journal of Materials Chemistry C Vol.5 No.15

<P>Visible emission colloidal quantum dots (QDs) have shown promise in optical and optoelectronic applications. These QDs are typically composed of relatively expensive elements in the form of indium, cadmium, and gallium since alternative candidate materials exhibiting similar properties are yet to be realized. Herein, for the first time, we report red green blue (RGB) photoluminescences with quantum yields of 18% from earth-abundant lead sulfide (PbS) QDs. The visible emissive property is mainly attributed to a high degree of crystallinity even for the extremely small QD sizes (1-3 nm), which is realized by employing a heterogeneous reaction methodology at high growth temperatures (>170 °C). We demonstrate that the proposed heterogeneous synthetic method can be extended to the synthesis of other metal chalcogenide QDs, such as zinc sulfide and zinc selenide, which are promising for future industrial applications. More importantly, benefiting from the enlarged band gaps, the as-prepared PbS solar cells show an impressive open circuit voltage (∼0.8 V) beyond that reported to date.</P>

Enhanced charge carrier transport properties in colloidal quantum dot solar cells <i>via</i> organic and inorganic hybrid surface passivation

Hong, John,Hou, Bo,Lim, Jongchul,Pak, Sangyeon,Kim, Byung-Sung,Cho, Yuljae,Lee, Juwon,Lee, Young-Woo,Giraud, Paul,Lee, Sanghyo,Park, Jong Bae,Morris, Stephen M.,Snaith, Henry J.,Sohn, Jung Inn,Cha, Se Royal Society of Chemistry 2016 Journal of materials chemistry. A, Materials for e Vol.4 No.48

<▼1><P>We report a PbS QD hybrid passivation structure to eliminate trap sites while increasing charge extraction in QD solar cells.</P></▼1><▼2><P>Colloidal quantum dots (CQDs) are extremely promising as photovoltaic materials. In particular, the tunability of their electronic band gap and cost effective synthetic procedures allow for the versatile fabrication of solar energy harvesting cells, resulting in optimal device performance. However, one of the main challenges in developing high performance quantum dot solar cells (QDSCs) is the improvement of the photo-generated charge transport and collection, which is mainly hindered by imperfect surface functionalization, such as the presence of surface electronic trap sites and the initial bulky surface ligands. Therefore, for these reasons, finding effective methods to efficiently decorate the surface of the as-prepared CQDs with new short molecular length chemical structures so as to enhance the performance of QDSCs is highly desirable. Here, we suggest employing hybrid halide ions along with the shortest heterocyclic molecule as a robust passivation structure to eliminate surface trap sites while decreasing the charge trapping dynamics and increasing the charge extraction efficiency in CQD active layers. This hybrid ligand treatment shows a better coordination with Pb atoms within the crystal, resulting in low trap sites and a near perfect removal of the pristine initial bulky ligands, thereby achieving better conductivity and film structure. Compared to halide ion-only treated cells, solar cells fabricated through this hybrid passivation method show an increase in the power conversion efficiency from 5.3% for the halide ion-treated cells to 6.8% for the hybrid-treated solar cells.</P></▼2>

Epithelial-to-mesenchymal transition drives a pro-metastatic Golgi compaction process through scaffolding protein PAQR11

Tan, Xiaochao,Banerjee, Priyam,Guo, Hou-Fu,Ireland, Stephen,Pankova, Daniela,Ahn, Young-ho,Nikolaidis, Irodotos Michail,Liu, Xin,Zhao, Yanbin,Xue, Yongming American Society for Clinical Investigation 2017 The Journal of clinical investigation Vol.127 No.1

<P>Tumor cells gain metastatic capacity through a Golgi phosphoprotein 3-dependent (GOLPH3-dependent) Golgi membrane dispersal process that drives the budding and transport of secretory vesicles. Whether Golgi dispersal underlies the pro-metastatic vesicular trafficking that is associated with epithelial-to-mesenchymal transition (EMT) remains unclear. Here, we have shown that, rather than causing Golgi dispersal, EMT led to the formation of compact Golgi organelles with improved ribbon linking and cisternal stacking. Ectopic expression of the EMT-activating transcription factor ZEB1 stimulated Golgi compaction and relieved microRNA-mediated repression of the Golgi scaffolding protein PAQR11. Depletion of PAQR11 dispersed Golgi organelles and impaired anterograde vesicle transport to the plasma membrane as well as retrograde vesicle tethering to the Golgi. The N-terminal scaffolding domain of PAQR11 was associated with key regulators of Golgi compaction and vesicle transport in pull-down assays and was required to reconstitute Golgi compaction in PAQR11-deficient tumor cells. Finally, high PAQR11 levels were correlated with EMT and shorter survival in human cancers, and PAQR11 was found to be essential for tumor cell migration and metastasis in EMT-driven lung adenocarcinoma models. We conclude that EMT initiates a PAQR11-mediated Golgi compaction process that drives metastasis.</P>

Assessing the Practical Differences in LDL-C Estimates Calculated by Friedewald, Martin/Hopkins, or NIH Equation 2: An Observation Cross-Sectional Study

Inga Wang,Mohammad H Rahman,Stephen Hou,Hui-Wen Lin 한국지질동맥경화학회 2023 지질·동맥경화학회지 Vol.12 No.3

Objective: Low-density lipoprotein-cholesterol (LDL-C) remains a clinically important cholesterol target in primary prevention of atherosclerotic cardiovascular disease. The present study aimed to assess the practical differences among three equations utilized for the estimation of LDL-C: the Friedewald, the Martin/Hopkins, and the NIH equation 2. Methods: Blood lipid measurements from 4,556 noninstitutionalized participants, aged 12 to 80, were obtained from the 2017-2020 National Health and Nutrition Examination Survey study. We 1) assessed the differences between three calculated LDL-C estimates, 2) examined the correlations between LDL-C estimates using correlation coefficients and regression, and 3) investigated the degree of agreement in classifying individuals into the LDL-C category using weighted Kappa and percentage of agreement. Results: The differences in LDL-C estimates between equations varied by sex and triglyceride levels (p<0.001). Overall, the mean of absolute differences between Friedewald and Martin/Hopkins was 3.17 mg/dL (median=2.0, 95% confidence interval [CI] [3.07–3.27]). The mean of absolute differences between Friedewald and NIH Equation 2 was 2.08 mg/dL (median=2.0, 95% CI [2.03–2.14]). Friedewald correlated highly with Martin/Hopkins (r=0.991, rho=0.989) and NIH Equation 2 (r=0.998, rho=0.997). Cohen’s weighted Kappa=0.92 between Friedewald and Martin/Hopkins, and 0.95 between Friedewald and NIH equation 2. The percentage of agreement in classifying individuals into the same LDL-C category was 93.0% between Friedewald and Martin/Hopkins, and 95.4% between Friedewald and NIH equation 2. Conclusion: Understanding the practical differences in LDL-C calculations can be helpful in facilitating decision-making during a paradigm shift.

Consecutive Junction-Induced Efficient Charge Separation Mechanisms for High-Performance MoS₂/Quantum Dot Phototransistors

Pak, Sangyeon,Cho, Yuljae,Hong, John,Lee, Juwon,Lee, Sanghyo,Hou, Bo,An, Geon-Hyoung,Lee, Young-Woo,Jang, Jae Eun,Im, Hyunsik,Morris, Stephen M.,Sohn, Jung Inn,Cha, SeungNam,Kim, Jong Min American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.44

<P>Phototransistors that are based on a hybrid vertical heterojunction structure of two-dimensional (2D)/quantum dots (QDs) have recently attracted attention as a promising device architecture for enhancing the quantum efficiency of photodetectors. However, to optimize the device structure to allow for more efficient charge separation and transfer to the electrodes, a better understanding of the photophysical mechanisms that take place in these architectures is required. Here, we employ a novel concept involving the modulation of the built-in potential within the QD layers for creating a new hybrid MoS<SUB>2</SUB>/PbS QDs phototransistor with consecutive type II junctions. The effects of the built-in potential across the depletion region near the type II junction interface in the QD layers are found to improve the photoresponse as well as decrease the response times to 950 μs, which is the faster response time (by orders of magnitude) than that recorded for previously reported 2D/QD phototransistors. Also, by implementing an electric-field modulation of the MoS<SUB>2</SUB> channel, our experimental results reveal that the detectivity can be as large as 1 × 10<SUP>11</SUP> jones. This work demonstrates an important pathway toward designing hybrid phototransistors and mixed-dimensional van der Waals heterostructures.</P> [FIG OMISSION]</BR>

The impact of microphysical schemes on hurricane intensity and track

Tao, Wei-Kuo,Shi, Jainn Jong,Chen, Shuyi S.,Lang, Stephen,Lin, Pay-Liam,Hong, Song-You,Peters-Lidard, Christa,Hou, Arthur Springer-Verlag 2011 Asia-Pacific Journal of Atmospheric Sciences Vol.47 No.1

Highly stable 3D porous heterostructures with hierarchically-coordinated octahedral transition metals for enhanced performance supercapacitors

Hong, John,Lee, Young-Woo,Ahn, Docheon,Pak, Sangyeon,Lee, Juwon,Jang, A-Rang,Lee, Sanghyo,Hou, Bo,Cho, Yuljae,Morris, Stephen M.,Shin, Hyeon Suk,Cha, SeungNam,Sohn, Jung Inn,Kim, Jong Min Elsevier 2017 Nano energy Vol.39 No.-

<P><B>Abstract</B></P> <P>Designing and tailoring the assembly of complex ternary transition metal oxide (TTMO) structures are a key step in the pursuit of high performance pseudo-capacitive materials for the development of next-generation energy storage devices. Here, we present uniquely assembled 3D porous heterostructures with hierarchically-coordinated TTMOs, comprising the multiply interconnected primary nanoporous frameworks of ZnCo<SUB>2</SUB>O<SUB>4</SUB>/NiMoO<SUB>4</SUB> core-shell structures and the secondary protruding structures of NiMoO<SUB>4</SUB> layered nanosheets. By benefiting from the combination of hierarchically cooperative two TTMOs, the developed 3D ZnCo<SUB>2</SUB>O<SUB>4</SUB>/NiMoO<SUB>4</SUB> heterostructures with their stable, porous, and conductive features exhibit robust pseudo-capacitive performance with high capacitances of 6.07Fcm<SUP>–2</SUP> and 1480.48Fg<SUP>–1</SUP> at 2mAcm<SUP>–2</SUP> as well as an excellent cycling stability of 90.6% over 15,000 cycles. Moreover, an asymmetric supercapacitor device can deliver a high energy density of 48.6Whkg<SUP>–1</SUP> and a power density of 2820Wkg<SUP>–1</SUP>. The superior pseudo-capacitive energy storage characteristics are strongly attributed to the interconnected 3D nanoporous network architectures of the TTMOs along with the secondary layered nanosheets that provide 1) the enlarged surface area with the high conductivity, 2) the facile and multi-access ion paths, and 3) the favorable structural stability. Combined, these results highlight the importance of novel nanostructure design in maximizing the pseudo-capacitive performance and provide a viable way to develop new electrode materials.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A hierarchically-coordinated two TTMOs based heterostructures were proposed and synthesized. </LI> <LI> The TTMOs showed multiple interconnected nanoporous architecture and protruding nanosheets. </LI> <LI> The resultant electrode exhibited high capacitance with ultra-high cyclability. </LI> <LI> The full cell demonstrated superior energy and power densities. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Genetic determinants of heel bone properties: genome-wide association meta-analysis and replication in the GEFOS/GENOMOS consortium

Moayyeri, Alireza,Hsu, Yi-Hsiang,Karasik, David,Estrada, Karol,Xiao, Su-Mei,Nielson, Carrie,Srikanth, Priya,Giroux, Sylvie,Wilson, Scott G.,Zheng, Hou-Feng,Smith, Albert V.,Pye, Stephen R.,Leo, Paul J IRL Press 2014 Human molecular genetics Vol.23 No.11

<P>Quantitative ultrasound of the heel captures heel bone properties that independently predict fracture risk and, with bone mineral density (BMD) assessed by X-ray (DXA), may be convenient alternatives for evaluating osteoporosis and fracture risk. We performed a meta-analysis of genome-wide association (GWA) studies to assess the genetic determinants of heel broadband ultrasound attenuation (BUA; <I>n</I> = 14 260), velocity of sound (VOS; <I>n</I> = 15 514) and BMD (<I>n</I> = 4566) in 13 discovery cohorts. Independent replication involved seven cohorts with GWA data (<I>in silico n</I> = 11 452) and new genotyping in 15 cohorts (<I>de novo n</I> = 24 902). In combined random effects, meta-analysis of the discovery and replication cohorts, nine single nucleotide polymorphisms (SNPs) had genome-wide significant (<I>P</I> < 5 × 10<SUP>−8</SUP>) associations with heel bone properties. Alongside SNPs within or near previously identified osteoporosis susceptibility genes including <I>ESR1</I> (6q25.1: rs4869739, rs3020331, rs2982552), <I>SPTBN1</I> (2p16.2: rs11898505), <I>RSPO3</I> (6q22.33: rs7741021), <I>WNT16</I> (7q31.31: rs2908007), <I>DKK1</I> (10q21.1: rs7902708) and <I>GPATCH1</I> (19q13.11: rs10416265), we identified a new locus on chromosome 11q14.2 (rs597319 close to <I>TMEM135</I>, a gene recently linked to osteoblastogenesis and longevity) significantly associated with both BUA and VOS (<I>P</I> < 8.23 × 10<SUP>−14</SUP>). In meta-analyses involving 25 cohorts with up to 14 985 fracture cases, six of 10 SNPs associated with heel bone properties at <I>P</I> < 5 × 10<SUP>−6</SUP> also had the expected direction of association with any fracture (<I>P</I> < 0.05), including three SNPs with <I>P</I> < 0.005: 6q22.33 (rs7741021), 7q31.31 (rs2908007) and 10q21.1 (rs7902708). In conclusion, this GWA study reveals the effect of several genes common to central DXA-derived BMD and heel ultrasound/DXA measures and points to a new genetic locus with potential implications for better understanding of osteoporosis pathophysiology.</P>