Showing papers by "Sungkyunkwan University published in 2013"
TL;DR: This paper demonstrates highly efficient solar cells exhibiting 12.3% in a power conversion efficiency of under standard AM 1.5, for the most efficient device, as a result of tunable composition for the light harvester in conjunction with a mesoporous TiO2 film and a hole conducting polymer.
Abstract: Chemically tuned inorganic–organic hybrid materials, based on CH3NH3(═MA)Pb(I1–xBrx)3 perovskites, have been studied using UV–vis absorption and X-ray diffraction patterns and applied to nanostructured solar cells. The band gap engineering brought about by the chemical management of MAPb(I1–xBrx)3 perovskites can be controllably tuned to cover almost the entire visible spectrum, enabling the realization of colorful solar cells. We demonstrate highly efficient solar cells exhibiting 12.3% in a power conversion efficiency of under standard AM 1.5, for the most efficient device, as a result of tunable composition for the light harvester in conjunction with a mesoporous TiO2 film and a hole conducting polymer. We believe that the works highlighted in this paper represent one step toward the realization of low-cost, high-efficiency, and long-term stability with colorful solar cells.
4,065 citations
Harvard University1, Seoul National University2, Kindai University3, Sungkyunkwan University4, Institut Gustave Roussy5, Peter MacCallum Cancer Centre6, Heidelberg University7, Trinity College, Dublin8, Joseph Fourier University9, University of Colorado Boulder10, The Chinese University of Hong Kong11, McGill University12, Memorial Sloan Kettering Cancer Center13, Pfizer14
TL;DR: Crizotinib is superior to standard chemotherapy in patients with previously treated, advanced non-small-cell lung cancer with ALK rearrangement and greater improvement in global quality of life with crizotinIB than with chemotherapy.
Abstract: BACKGROUND: In single-group studies, chromosomal rearrangements of the anaplastic lymphoma kinase gene (ALK ) have been associated with marked clinical responses to crizotinib, an oral tyrosine kinase inhibitor targeting ALK. Whether crizotinib is superior to standard chemotherapy with respect to efficacy is unknown. METHODS: We conducted a phase 3, open-label trial comparing crizotinib with chemotherapy in 347 patients with locally advanced or metastatic ALK-positive lung cancer who had received one prior platinum-based regimen. Patients were randomly assigned to receive oral treatment with crizotinib (250 mg) twice daily or intravenous chemotherapy with either pemetrexed (500 mg per square meter of body-surface area) or docetaxel (75 mg per square meter) every 3 weeks. Patients in the chemotherapy group who had disease progression were permitted to cross over to crizotinib as part of a separate study. The primary end point was progression-free survival. RESULTS: The median progression-free survival was 7.7 months in the crizotinib group and 3.0 months in the chemotherapy group (hazard ratio for progression or death with crizotinib, 0.49; 95% confidence interval [CI], 0.37 to 0.64; P<0.001). The response rates were 65% (95% CI, 58 to 72) with crizotinib, as compared with 20% (95% CI, 14 to 26) with chemotherapy (P<0.001). An interim analysis of overall survival showed no significant improvement with crizotinib as compared with chemotherapy (hazard ratio for death in the crizotinib group, 1.02; 95% CI, 0.68 to 1.54; P=0.54). Common adverse events associated with crizotinib were visual disorder, gastrointestinal side effects, and elevated liver aminotransferase levels, whereas common adverse events with chemotherapy were fatigue, alopecia, and dyspnea. Patients reported greater reductions in symptoms of lung cancer and greater improvement in global quality of life with crizotinib than with chemotherapy. CONCLUSIONS: Crizotinib is superior to standard chemotherapy in patients with previously treated, advanced non-small-cell lung cancer with ALK rearrangement. (Funded by Pfizer; ClinicalTrials.gov number, NCT00932893.) Copyright © 2013 Massachusetts Medical Society.
3,074 citations
TL;DR: In this paper, a layered sandwich-type architecture is proposed for next-generation dye-sensitized solar cells, which consists of a bicontinuous three-dimensional nanocomposite of mesoporous (mp)-TiO2,w ith CH 3NH3PbII3 perovskite as light harvester, as well as a polymeric hole conductor.
Abstract: Inorganic‐organic hybrid structures have become innovative alternatives for next-generation dye-sensitized solar cells, because they combine the advantages of both systems. Here, we introduce a layered sandwich-type architecture, the core of which comprises a bicontinuous three-dimensional nanocomposite of mesoporous (mp)-TiO2 ,w ith CH 3NH3PbI3 perovskite as light harvester, as well as a polymeric hole conductor. This platform creates new opportunities for the development of low-cost, solution-processed, high-efficiency solar cells. The use of a polymeric hole conductor, especially poly-triarylamine, substantially improves the open-circuit voltage V oc and fill factor of the cells. Solar cells based on these inorganic‐organic hybrids exhibit a short-circuit current density Jsc of 16.5 mA cm 22 , Voc of 0.997 V and fill factor of 0.727, yielding a power conversion efficiency of 12.0% under standard AM 1.5 conditions.
2,461 citations
TL;DR: The spectroscopic identification in a monolayer MoS(2) field-effect transistor of tightly bound negative trions, a quasiparticle composed of two electrons and a hole is reported, which has no analogue in conventional semiconductors.
Abstract: The appealing electronic properties of the monolayer semiconductor molybdenum disulphide make it a candidate material for electronic devices. The observation of tightly bound trions in this system—which have no analogue in conventional semiconductors—opens up possibilities for controlling these quasiparticles in future optoelectronic applications.
2,447 citations
Panos Deloukas1, Stavroula Kanoni1, Christina Willenborg2, Martin Farrall3 +201 more•Institutions (64)
TL;DR: An association analysis in CAD cases and controls identifies 15 loci reaching genome-wide significance, taking the number of susceptibility loci for CAD to 46, and a further 104 independent variants strongly associated with CAD at a 5% false discovery rate (FDR).
Abstract: Coronary artery disease (CAD) is the commonest cause of death. Here, we report an association analysis in 63,746 CAD cases and 130,681 controls identifying 15 loci reaching genome-wide significance, taking the number of susceptibility loci for CAD to 46, and a further 104 independent variants (r(2) < 0.2) strongly associated with CAD at a 5% false discovery rate (FDR). Together, these variants explain approximately 10.6% of CAD heritability. Of the 46 genome-wide significant lead SNPs, 12 show a significant association with a lipid trait, and 5 show a significant association with blood pressure, but none is significantly associated with diabetes. Network analysis with 233 candidate genes (loci at 10% FDR) generated 5 interaction networks comprising 85% of these putative genes involved in CAD. The four most significant pathways mapping to these networks are linked to lipid metabolism and inflammation, underscoring the causal role of these activities in the genetic etiology of CAD. Our study provides insights into the genetic basis of CAD and identifies key biological pathways.
1,518 citations
TL;DR: In this article, the perovskite CH3NH3PbX3 (X = Cl, Br, or I) sensitizer made a breakthrough in solid-state mescoscopic solar cells, where the first record efficiency of around 10% was reported in 2012 using submicrometer-thick TiO2 film sensitized with CH 3NH3pbI3. A rapid increase in efficiency approaching 14% followed shortly.
Abstract: Recently, perovskite CH3NH3PbI3 sensitizer has attracted great attention due to its superb light-harvesting characteristics. Organometallic or organic materials were mostly used as sensitizers for solid-state dye-sensitized solar cells at early stages. Inorganic nanocrystals have lately received attention as light harvesters due to their high light-absorbing properties. Metal chalcogenides have been investigated with solid-state dye-sensitized solar cells; however, the best power conversion efficiency was reported to be around 6%. CH3NH3PbX3 (X = Cl, Br, or I) perovskite sensitizer made a breakthrough in solid-state mescoscopic solar cells, where the first record efficiency of around 10% was reported in 2012 using submicrometer-thick TiO2 film sensitized with CH3NH3PbI3. A rapid increase in efficiency approaching 14% followed shortly. In this Perspective, recent progress in perovskite-sensitized solid-state mesoscopic solar cells is reviewed. On the basis of the recent achievements, a power conversion eff...
1,275 citations
TL;DR: The ability of these ultrathin, mechanically compliant, biocompatible devices to afford minimally invasive operation in the soft tissues of the mammalian brain foreshadow applications in other organ systems, with potential for broad utility in biomedical science and engineering.
Abstract: Successful integration of advanced semiconductor devices with biological systems will accelerate basic scientific discoveries and their translation into clinical technologies. In neuroscience generally, and in optogenetics in particular, the ability to insert light sources, detectors, sensors, and other components into precise locations of the deep brain yields versatile and important capabilities. Here, we introduce an injectable class of cellular-scale optoelectronics that offers such features, with examples of unmatched operational modes in optogenetics, including completely wireless and programmed complex behavioral control over freely moving animals. The ability of these ultrathin, mechanically compliant, biocompatible devices to afford minimally invasive operation in the soft tissues of the mammalian brain foreshadow applications in other organ systems, with potential for broad utility in biomedical science and engineering.
1,006 citations
TL;DR: This work demonstrates field-effect transistors with MoS2 channels, hBN dielectric, and graphene gate electrodes, and takes advantage of the mechanical strength and flexibility of these materials to create flexible and transparent FETs that show unchanged performance up to 1.5% strain.
Abstract: Atomically thin forms of layered materials, such as conducting graphene, insulating hexagonal boron nitride (hBN), and semiconducting molybdenum disulfide (MoS2), have generated great interests recently due to the possibility of combining diverse atomic layers by mechanical “stacking” to create novel materials and devices. In this work, we demonstrate field-effect transistors (FETs) with MoS2 channels, hBN dielectric, and graphene gate electrodes. These devices show field-effect mobilities of up to 45 cm2/Vs and operating gate voltage below 10 V, with greatly reduced hysteresis. Taking advantage of the mechanical strength and flexibility of these materials, we demonstrate integration onto a polymer substrate to create flexible and transparent FETs that show unchanged performance up to 1.5% strain. These heterostructure devices consisting of ultrathin two-dimensional (2D) materials open up a new route toward high-performance flexible and transparent electronics.
1,004 citations
TL;DR: A continuous drop of voltage with increasing nanorod length correlated with charge generation efficiency rather than recombination kinetics with impedance spectroscopic characterization displaying similar recombination regardless of the nanorods length.
Abstract: We report a highly efficient solar cell based on a submicrometer (∼0.6 μm) rutile TiO2 nanorod sensitized with CH3NH3PbI3 perovskite nanodots. Rutile nanorods were grown hydrothermally and their lengths were varied through the control of the reaction time. Infiltration of spiro-MeOTAD hole transport material into the perovskite-sensitized nanorod films demonstrated photocurrent density of 15.6 mA/cm2, voltage of 955 mV, and fill factor of 0.63, leading to a power conversion efficiency (PCE) of 9.4% under the simulated AM 1.5G one sun illumination. Photovoltaic performance was significantly dependent on the length of the nanorods, where both photocurrent and voltage decreased with increasing nanorod lengths. A continuous drop of voltage with increasing nanorod length correlated with charge generation efficiency rather than recombination kinetics with impedance spectroscopic characterization displaying similar recombination regardless of the nanorod length.
893 citations
TL;DR: It is shown that the elastic stiffness of CVD-graphene is identical to that of pristine graphene if postprocessing steps avoid damage or rippling, and its strength is only slightly reduced despite the existence of grain boundaries.
Abstract: Pristine graphene is the strongest material ever measured. However, large-area graphene films produced by means of chemical vapor deposition (CVD) are polycrystalline and thus contain grain boundaries that can potentially weaken the material. We combined structural characterization by means of transmission electron microscopy with nanoindentation in order to study the mechanical properties of CVD-graphene films with different grain sizes. We show that the elastic stiffness of CVD-graphene is identical to that of pristine graphene if postprocessing steps avoid damage or rippling. Its strength is only slightly reduced despite the existence of grain boundaries. Indentation tests directly on grain boundaries confirm that they are almost as strong as pristine. Graphene films consisting entirely of well-stitched grain boundaries can retain ultrahigh strength, which is critical for a large variety of applications, such as flexible electronics and strengthening components.
763 citations
TL;DR: A fingerprint of the charge accumulation in high density of states of the perovskite absorber material has been observed at the capacitance of the samples, indicating that it constitutes a new kind of photovoltaic device, differentiated from sensitized solar cells, which will require its own methods of study, characterization and optimization.
Abstract: Photovoltaic conversion requires two successive steps: accumulation of a photogenerated charge and charge separation. Determination of how and where charge accumulation is attained and how this accumulation can be identified is mandatory for understanding the performance of a photovoltaic device and for its further optimization. Here we analyse the mechanism of carrier accumulation in lead halide perovskite, CH3NH3PbI3, thin-absorber solar cells by means of impedance spectroscopy. A fingerprint of the charge accumulation in high density of states of the perovskite absorber material has been observed at the capacitance of the samples. This is, as far as we know, the first observation of charge accumulation in light-absorbing material for nanostructured solar cells, indicating that it constitutes a new kind of photovoltaic device, differentiated from sensitized solar cells, which will require its own methods of study, characterization and optimization.
TL;DR: Addition of cetuximab to capecitabine-cisplatin provided no additional benefit to chemotherapy alone in the first-line treatment of advanced gastric cancer in the EXPAND trial.
Abstract: Summary Background Patients with advanced gastric cancer have a poor prognosis and few efficacious treatment options. We aimed to assess the addition of cetuximab to capecitabine-cisplatin chemotherapy in patients with advanced gastric or gastro-oesophageal junction cancer. Methods In our open-label, randomised phase 3 trial (EXPAND), we enrolled adults aged 18 years or older with histologically confirmed locally advanced unresectable (M0) or metastatic (M1) adenocarcinoma of the stomach or gastro-oesophageal junction. We enrolled patients at 164 sites (teaching hospitals and clinics) in 25 countries, and randomly assigned eligible participants (1:1) to receive first-line chemotherapy with or without cetuximab. Randomisation was done with a permuted block randomisation procedure (variable block size), stratified by disease stage (M0 vs M1), previous oesophagectomy or gastrectomy (yes vs no), and previous (neo)adjuvant (radio)chemotherapy (yes vs no). Treatment consisted of 3-week cycles of twice-daily capecitabine 1000 mg/m 2 (on days 1–14) and intravenous cisplatin 80 mg/m 2 (on day 1), with or without weekly cetuximab (400 mg/m 2 initial infusion on day 1 followed by 250 mg/m 2 per week thereafter). The primary endpoint was progression-free survival (PFS), assessed by a masked independent review committee in the intention-to-treat population. We assessed safety in all patients who received at least one dose of study drug. This study is registered at EudraCT, number 2007-004219-75. Findings Between June 30, 2008, and Dec 15, 2010, we enrolled 904 patients. Median PFS for 455 patients allocated capecitabine-cisplatin plus cetuximab was 4·4 months (95% CI 4·2–5·5) compared with 5·6 months (5·1–5·7) for 449 patients who were allocated to receive capecitabine-cisplatin alone (hazard ratio 1·09, 95% CI 0·92–1·29; p=0·32). 369 (83%) of 446 patients in the chemotherapy plus cetuximab group and 337 (77%) of 436 patients in the chemotherapy group had grade 3–4 adverse events, including grade 3–4 diarrhoea, hypokalaemia, hypomagnesaemia, rash, and hand-foot syndrome. Grade 3–4 neutropenia was more common in controls than in patients who received cetuximab. Incidence of grade 3–4 skin reactions and acne-like rash was substantially higher in the cetuximab-containing regimen than in the control regimen. 239 (54%) of 446 in the cetuximab group and 194 (44%) of 436 in the control group had any grade of serious adverse event. Interpretation Addition of cetuximab to capecitabine-cisplatin provided no additional benefit to chemotherapy alone in the first-line treatment of advanced gastric cancer in our trial. Funding Merck KGaA.
TL;DR: Transparent strain sensors based on graphene were fabricated in a form of rosette on a flexible plastic or stretchable rubber substrate by using reactive ion etching and stamping techniques.
TL;DR: It is suggested that autophagy deficiency and subsequent mitochondrial dysfunction promote Fgf21 expression, a hormone the authors consequently term a 'mitokine', and together these processes promote protection from diet-induced obesity and insulin resistance.
Abstract: Despite growing interest and a recent surge in papers, the role of autophagy in glucose and lipid metabolism is unclear. We produced mice with skeletal muscle–specific deletion of Atg7 (encoding autophagy-related 7). Unexpectedly, these mice showed decreased fat mass and were protected from diet-induced obesity and insulin resistance; this phenotype was accompanied by increased fatty acid oxidation and browning of white adipose tissue (WAT) owing to induction of fibroblast growth factor 21 (Fgf21). Mitochondrial dysfunction induced by autophagy deficiency increased Fgf21 expression through induction of Atf4, a master regulator of the integrated stress response. Mitochondrial respiratory chain inhibitors also induced Fgf21 in an Atf4-dependent manner. We also observed induction of Fgf21, resistance to diet-induced obesity and amelioration of insulin resistance in mice with autophagy deficiency in the liver, another insulin target tissue. These findings suggest that autophagy deficiency and subsequent mitochondrial dysfunction promote Fgf21 expression, a hormone we consequently term a 'mitokine', and together these processes promote protection from diet-induced obesity and insulin resistance.
TL;DR: JX-594 demonstrated oncolytic and immunotherapy MOA, tumor responses and dose-related survival in individuals with HCC, and subject survival duration was significantly related to dose.
Abstract: Oncolytic viruses and active immunotherapeutics have complementary mechanisms of action (MOA) that are both self amplifying in tumors, yet the impact of dose on subject outcome is unclear. JX-594 (Pexa-Vec) is an oncolytic and immunotherapeutic vaccinia virus. To determine the optimal JX-594 dose in subjects with advanced hepatocellular carcinoma (HCC), we conducted a randomized phase 2 dose-finding trial (n=30). Radiologists infused low- or high-dose JX-594 into liver tumors (days 1, 15 and 29); infusions resulted in acute detectable intravascular JX-594 genomes. Objective intrahepatic Modified Response Evaluation Criteria in Solid Tumors (mRECIST) (15%) and Choi (62%) response rates and intrahepatic disease control (50%) were equivalent in injected and distant noninjected tumors at both doses. JX-594 replication and granulocyte-macrophage colony-stimulating factor (GM-CSF) expression preceded the induction of anticancer immunity. In contrast to tumor response rate and immune endpoints, subject survival duration was significantly related to dose (median survival of 14.1 months compared to 6.7 months on the high and low dose, respectively; hazard ratio 0.39; P=0.020). JX-594 demonstrated oncolytic and immunotherapy MOA, tumor responses and dose-related survival in individuals with HCC.
TL;DR: These non-volatile memory devices, based on field-effect transistors with large hysteresis, consisting entirely of stacked two-dimensional materials show high mobility, high on/off current ratio, large memory window and stable retention, providing a promising route towards flexible and transparent memory devices utilizing atomically thin two- dimensional materials.
Abstract: Atomically thin two-dimensional materials have emerged as promising candidates for flexible and transparent electronic applications. Here we show non-volatile memory devices, based on field-effect transistors with large hysteresis, consisting entirely of stacked two-dimensional materials. Graphene and molybdenum disulphide were employed as both channel and charge-trapping layers, whereas hexagonal boron nitride was used as a tunnel barrier. In these ultrathin heterostructured memory devices, the atomically thin molybdenum disulphide or graphene-trapping layer stores charge tunnelled through hexagonal boron nitride, serving as a floating gate to control the charge transport in the graphene or molybdenum disulphide channel. By varying the thicknesses of two-dimensional materials and modifying the stacking order, the hysteresis and conductance polarity of the field-effect transistor can be controlled. These devices show high mobility, high on/off current ratio, large memory window and stable retention, providing a promising route towards flexible and transparent memory devices utilizing atomically thin two-dimensional materials.
University of Birmingham1, Wayne State University2, National Taiwan University3, Chang Gung University4, Pusan National University5, Samsung Medical Center6, University of Paris-Est7, Sungkyunkwan University8, Kindai University9, Sichuan University10, Mahidol University11, Russian Academy12, Kyungpook National University13, Bristol-Myers Squibb14
TL;DR: Brivanib had an acceptable safety profile, but was less well-tolerated than sorafenib, and both agents had similar antitumor activity, based on secondary efficacy end points.
Abstract: Purpose Brivanib is a dual inhibitor of vascular-endothelial growth factor and fibroblast growth factor receptors that are implicated in the pathogenesis of hepatocellular carcinoma (HCC). Our multinational, randomized, double-blind, phase III trial compared brivanib with sorafenib as first-line treatment for HCC. Patients and Methods Advanced HCC patients who had no prior systemic therapy were randomly assigned (ratio, 1:1) to receive sorafenib 400 mg twice daily orally (n = 578) or brivanib 800 mg once daily orally (n = 577). Primary end point was overall survival (OS). Secondary end points included time to progression (TTP), objective response rate (ORR), disease control rate (DCR) based on modified Response Evaluation Criteria in Solid Tumors (mRECIST), and safety. Results The primary end point of OS noninferiority for brivanib versus sorafenib in the per-protocol population (n = 1,150) was not met (hazard ratio [HR], 1.06; 95.8% CI, 0.93 to 1.22), based on the prespecified margin (upper CI limit for ...
TL;DR: In this article, a detailed description of the analysis used by the CMS Collaboration in the search for the standard model Higgs boson in pp collisions at the LHC, which led to the observation of a new boson.
Abstract: A detailed description is reported of the analysis used by the CMS Collaboration in the search for the standard model Higgs boson in pp collisions at the LHC, which led to the observation of a new boson. The data sample corresponds to integrated luminosities up to 5.1 inverse femtobarns at sqrt(s) = 7 TeV, and up to 5.3 inverse femtobarns at sqrt(s) = 8 TeV. The results for five Higgs boson decay modes gamma gamma, ZZ, WW, tau tau, and bb, which show a combined local significance of 5 standard deviations near 125 GeV, are reviewed. A fit to the invariant mass of the two high resolution channels, gamma gamma and ZZ to 4 ell, gives a mass estimate of 125.3 +/- 0.4 (stat) +/- 0.5 (syst) GeV. The measurements are interpreted in the context of the standard model Lagrangian for the scalar Higgs field interacting with fermions and vector bosons. The measured values of the corresponding couplings are compared to the standard model predictions. The hypothesis of custodial symmetry is tested through the measurement of the ratio of the couplings to the W and Z bosons. All the results are consistent, within their uncertainties, with the expectations for a standard model Higgs boson.
TL;DR: It is shown that EZH2 binds to and methylates STAT3, leading to enhanced STAT3 activity by increased tyrosine phosphorylation of STAT3.
TL;DR: In a study of Y(4260) → π+ π- J/φ decays, a structure is observed in the M(π(±)J/ψ) mass spectrum with 5.2σ significance that can be interpreted as a new charged charmoniumlike state.
Abstract: The cross section for ee+ e- → π+ π- J/ψ between 3.8 and 5.5 GeV is measured with a 967 fb(-1) data sample collected by the Belle detector at or near the Υ(nS) (n = 1,2,…,5) resonances. The Y(4260) state is observed, and its resonance parameters are determined. In addition, an excess of π+ π- J/ψ production around 4 GeV is observed. This feature can be described by a Breit-Wigner parametrization with properties that are consistent with the Y(4008) state that was previously reported by Belle. In a study of Y(4260) → π+ π- J/ψ decays, a structure is observed in the M(π(±)J/ψ) mass spectrum with 5.2σ significance, with mass M = (3894.5 ± 6.6 ± 4.5) MeV/c2 and width Γ = (63 ± 24 ± 26) MeV/c2, where the errors are statistical and systematic, respectively. This structure can be interpreted as a new charged charmoniumlike state.
TL;DR: In this paper, a self-assembled reduced graphene oxide (RGO)/MnO2/GrMoO(2) composite was used as a positive electrode and a RGO/MoO3 composite as a negative electrode in safe aqueous Na2SO4 electrolyte.
Abstract: Asymmetric supercapacitors with high energy density are fabricated using a self-assembled reduced graphene oxide (RGO)/MnO2 (GrMnO(2)) composite as a positive electrode and a RGO/MoO3 (GrMoO(3)) composite as a negative electrode in safe aqueous Na2SO4 electrolyte. The operation voltage is maximized by choosing two metal oxides with the largest work function difference. Because of the synergistic effects of highly conductive graphene and highly pseudocapacitive metal oxides, the hybrid nanostructure electrodes exhibit better charge transport and cycling stability. The operation voltage is expanded to 2.0 V in spite of the use of aqueous electrolyte, revealing a high energy density of 42.6 Wh kg(-1) at a power density of 276 W kg(-1) and a maximum specific capacitance of 307 F g(-1), consequently giving rise to an excellent Ragone plot. In addition, the GrMnO(2)//GrMoO(3) supercapacitor exhibits improved capacitance with cycling up to 1000 cycles, which is explained by the development of micropore structures during the repetition of ion transfer. This strategy for the choice of metal oxides provides a promising route for next-generation supercapacitors with high energy and high power densities.
TL;DR: In this paper, two-particle angular correlations for charged particles emitted in pPb collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV are presented.
Radboud University Nijmegen1, University of Picardie Jules Verne2, Karolinska Institutet3, French Institute of Health and Medical Research4, Instituto Adolfo Lutz5, Complutense University of Madrid6, Autonomous University of Madrid7, University of Colorado Denver8, Health Protection Agency9, Statens Serum Institut10, Trinity College, Dublin11, National Taiwan University12, University of Warsaw13, Ontario Ministry of the Environment14, University of Zagreb15, University of the Witwatersrand16, Sungkyunkwan University17, University of Freiburg18, Federal University of São Paulo19, Norwegian Institute of Public Health20, University of Toronto21, University of Bordeaux22, Guy's and St Thomas' NHS Foundation Trust23, United Hospitals24, Pasteur Institute25, National Health Laboratory Service26, Greenslopes Private Hospital27, Autonomous University of Barcelona28, University of Calgary29, National Institute for Health and Welfare30, Medical University of Warsaw31, Oregon Health & Science University32
TL;DR: A snapshot of NTM species distribution demonstrates that the species distribution among NTM isolates from pulmonary specimens in the year 2008 differed by continent and differed by country within these continents.
Abstract: A significant knowledge gap exists concerning the geographical distribution of nontuberculous mycobacteria (NTM) isolation worldwide. To provide a snapshot of NTM species distribution, global partners in the NTM-Network European Trials Group (NET) framework (www.ntm-net.org), a branch of the Tuberculosis Network European Trials Group (TB-NET), provided identification results of the total number of patients in 2008 in whom NTM were isolated from pulmonary samples. From these data, we visualised the relative distribution of the different NTM found per continent and per country. We received species identification data for 20 182 patients, from 62 laboratories in 30 countries across six continents. 91 different NTM species were isolated. Mycobacterium avium complex (MAC) bacteria predominated in most countries, followed by M. gordonae and M. xenopi. Important differences in geographical distribution of MAC species as well as M. xenopi, M. kansasii and rapid-growing mycobacteria were observed. This snapshot demonstrates that the species distribution among NTM isolates from pulmonary specimens in the year 2008 differed by continent and differed by country within these continents. These differences in species distribution may partly determine the frequency and manifestations of pulmonary NTM disease in each geographical location.
TL;DR: A deep understanding of the shape-dependent catalytic properties, together with an ability to experimentally maneuver the shape of metal nanocrystals, will eventually lead to rational design of advanced catalysts with substantially enhanced performance.
Abstract: Palladium is a marvelous catalyst for a rich variety of reactions in industrial processes and commercial devices. Most Pd-catalyzed reactions exhibit structure sensitivity, meaning that the activity or selectivity depends on the arrangement of atoms on the surface. Previously, such reactions could only be studied in ultrahigh vacuum using Pd single crystals cut with a specific crystallographic plane. However, these model catalysts are far different from real catalytic systems owing to the absence of atoms at corners and edges and the extremely small specific surface areas for the model systems. Indeed, enhancing the performance of a Pd-based catalyst, in part to reduce the amount needed of this precious and rare metal for a given reaction, requires the use of Pd with the highest possible specific surface area. Recent advances in nanocrystal synthesis are offering a great opportunity to investigate and quantify the structural sensitivity of catalysts based on Pd and other metals. For a structure-sensitive reaction, the catalytic properties of Pd nanocrystals are strongly dependent on both the size and shape. The shape plays a more significant role in controlling activity and selectivity, because the shape controls not only the facets but also the proportions of surface atoms at corners, edges, and planes, which affect the outcomes of possible reactions. We expect catalysts based on Pd nanocrystals with optimized shapes to meet the increasing demands of industrial applications at reduced loadings and costs. In this Account, we discuss recent advances in the synthesis of Pd nanocrystals with controlled shapes and their resulting performance as catalysts for a large number of reactions. First, we review various synthetic strategies based on oxidative etching, surface capping, and kinetic control that have been used to direct the shapes of nanocrystals. When crystal growth is under thermodynamic control, the capping agent plays a pivotal role in determining the shape of a product by altering the order of surface energies for different facets through selective adsorption; the resulting product has the lowest possible total surface energy. In contrast, the product of a kinetically controlled synthesis often deviates from the thermodynamically favored structure, with notable examples including nanocrystals enclosed by high-index facets or concave surfaces. We then discuss the key parameters that control the nucleation and growth of Pd nanocrystals to decipher potential growth mechanisms and build a connection between the experimental conditions and the pathways to different shapes. Finally, we present a number of examples to highlight the use of these Pd nanocrystals as catalysts or electrocatalysts for various applications with structure-sensitive properties. We believe that a deep understanding of the shape-dependent catalytic properties, together with an ability to experimentally maneuver the shape of metal nanocrystals, will eventually lead to rational design of advanced catalysts with substantially enhanced performance.
TL;DR: A new pathway is reported to greatly reduce the graphene nucleation density from ~10(6) to 4 nuclei cm(-2), enabling the growth of giant single crystals of monolayer graphene with a lateral size up to 5 mm and Bernal-stacked bilayers graphene with the lateral sizes up to 300 μm, both the largest reported to date.
Abstract: The growth of large-domain single crystalline graphene with the controllable number of layers is of central importance for large-scale integration of graphene devices. Here we report a new pathway to greatly reduce the graphene nucleation density from ~10(6) to 4 nuclei cm(-2), enabling the growth of giant single crystals of monolayer graphene with a lateral size up to 5 mm and Bernal-stacked bilayer graphene with the lateral size up to 300 μm, both the largest reported to date. The formation of the giant graphene single crystals eliminates the grain boundary scattering to ensure excellent device-to-device uniformity and remarkable electronic properties with the expected quantum Hall effect and the highest carrier mobility up to 16,000 cm(2) V(-1) s(-1). The availability of the ultra large graphene single crystals can allow for high-yield fabrication of integrated graphene devices, paving a pathway to scalable electronic and photonic devices based on graphene materials.
TL;DR: This newly synthesized pyrene derivative holds promise as a HTM for highly efficient perovskite-based solar cells, comparable to that of the well-studied spiro-OMeTAD.
Abstract: A set of three N,N-di-p-methoxyphenylamine-substituted pyrene derivatives have successfully been synthesized and characterized by 1H/13C NMR spectroscopy, mass spectrometry, and elemental analysis. The optical and electronic structures of the pyrene derivatives were adjusted by controlling the ratio of N,N-di-p-methoxyphenylamine to pyrene, and investigated by UV/vis spectroscopy and cyclic voltammetry. The pyrene derivatives were employed as hole-transporting materials (HTMs) in fabricating mesoporous TiO2/CH3NH3PbI3/HTMs/Au solar cells. The pyrene-based derivative Py-C exhibited a short-circuit current density of 20.2 mA/cm2, an open-circuit voltage (Voc) of 0.886 V, and a fill factor of 69.4% under an illumination of 1 sun (100 mW/cm2), resulting in an overall power conversion efficiency of 12.4%. The performance is comparable to that of the well-studied spiro-OMeTAD, even though the Voc is slightly lower. Thus, this newly synthesized pyrene derivative holds promise as a HTM for highly efficient perovs...
TL;DR: The high capacitance, high energy density, and power density of the coaxial fiber supercapacitor are attributed to not only high effective surface area due to its coaxial structure and bundle of the core electrode, but also all-carbon materials electrodes which have high conductivity.
Abstract: We report a coaxial fiber supercapacitor, which consists of carbon microfiber bundles coated with multiwalled carbon nanotubes as a core electrode and carbon nanofiber paper as an outer electrode. The ratio of electrode volumes was determined by a half-cell test of each electrode. The capacitance reached 6.3 mF cm–1 (86.8 mF cm–2) at a core electrode diameter of 230 μm and the measured energy density was 0.7 μWh cm–1 (9.8 μWh cm–2) at a power density of 13.7 μW cm–1 (189.4 μW cm–2), which were much higher than the previous reports. The change in the cyclic voltammetry characteristics was negligible at 180° bending, with excellent cycling performance. The high capacitance, high energy density, and power density of the coaxial fiber supercapacitor are attributed to not only high effective surface area due to its coaxial structure and bundle of the core electrode, but also all-carbon materials electrodes which have high conductivity. Our coaxial fiber supercapacitor can promote the development of textile ele...
TL;DR: Galvanic replacement reactions provide a simple and versatile route for producing hollow nanostructures with controllable pore structures and compositions and were demonstrated in metal oxide nanocrystals as well.
Abstract: Galvanic replacement reactions provide a simple and versatile route for producing hollow nanostructures with controllable pore structures and compositions. However, these reactions have previously been limited to the chemical transformation of metallic nanostructures. We demonstrated galvanic replacement reactions in metal oxide nanocrystals as well. When manganese oxide (Mn3O4) nanocrystals were reacted with iron(II) perchlorate, hollow box-shaped nanocrystals of Mn3O4/γ-Fe2O3 ("nanoboxes") were produced. These nanoboxes ultimately transformed into hollow cagelike nanocrystals of γ-Fe2O3 ("nanocages"). Because of their nonequilibrium compositions and hollow structures, these nanoboxes and nanocages exhibited good performance as anode materials for lithium ion batteries. The generality of this approach was demonstrated with other metal pairs, including Co3O4/SnO2 and Mn3O4/SnO2.
TL;DR: In the biochar yield, the influence of the inert and lignin contents was significant, and PKS biochar had dense matrix with few large pores, while the elemental composition and pH of biochars were compared.
TL;DR: This paper found that credit rating agencies tend to award relatively high ratings to firms with good social performance and that the individual components of CSR that relate to primary stakeholder management (i.e., community relations, diversity, employee relations, environmental performance, and product characteristics) matter most in explaining firms' creditworthiness.
Abstract: This study provides evidence on the relationship between corporate social responsibility (CSR) and firms’ credit ratings. We find that credit rating agencies tend to award relatively high ratings to firms with good social performance. This pattern is robust to controlling for key firm characteristics as well as endogeneity between CSR and credit ratings. We also find that CSR strengths and concerns influence credit ratings and that the individual components of CSR that relate to primary stakeholder management (i.e., community relations, diversity, employee relations, environmental performance, and product characteristics) matter most in explaining firms’ creditworthiness. Overall, our results suggest that CSR performance conveys important non-financial information that rating agencies are likely to use in their evaluation of firms’ creditworthiness, and that CSR investments—particularly those that extend beyond compliance behavior to reflect what is desired by society—can lead to lower financing costs resulting from higher credit ratings.