Browsing by Author "Zhang, P."

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Open Access
CdSe/CdMnS nanoplatelets with bilayer core and magnetically doped shell exhibit switchable excitonic circular polarization: Implications for lasers and light-emitting diodes
(American Chemical Society, 2020-03) Najafi, A.; Tarasek, S.; Delikanlı, Savaş; Zhang, P.; Norden, T.; Shendre, S.; Sharma, Manoj; Bhattacharya, A.; Taghipour, Nima; Pientka, J.; Dedmir, Hilmi Volkan; Thomay, T.
We utilized time-resolved photoluminescence (TRPL) spectroscopy to study the excitonic circular polarization (PX) from CdSe/CdMnS core/shell nanoplatelets (NPLs) with a bilayer core. This allows an extensive study of the emission dynamics as a function of magnetic field, temperature, doping concentration, and excitation wavelength. In the presence of an external magnetic field, pulsed excitation below the shell gap results in near-zero excitonic circular polarization PX at all time delays. In contrast, pulsed excitation with photon energy larger than the shell gap results in a rapid (100 ps) buildup of the excitonic circular polarization which subsequently remains constant at a level of up to 40%. We propose a model to describe the dynamics which takes into account the exchange interaction between carrier and magnetic ion (Mn) spins. The studied system exhibits a fast switchable excitonic circular polarization, implying possible applications in lasers and light emitting diodes.
Open Access
Human STAT3 variants underlie autosomal dominant hyper-IgE syndrome by negative dominance
(Rockefeller University Press, 2021-06-17) Asano, T.; Khourieh, J.; Zhang, P.; Rapaport, F.; Spaan, A. N.; Li, J.; Lei, W. T.; Pelham, S. J.; Hum, D.; Chrabieh, M.; Han, J. E.; Guérin, A.; Mackie, J.; Gupta, S.; Saikia, B.; Baghdadi, J. E. I.; Fadil, I.; Bousfiha, A.; Habib, T.; Marr, N.; Ganeshanandan, L.; Peake, J.; Droney, L.; Williams, A.; Celmeli, F.; Hatipoglu, N.; Özçelik, Tayfun; Picard, C.
Most patients with autosomal dominant hyper-IgE syndrome (AD-HIES) carry rare heterozygous STAT3 variants. Only six of the 135 in-frame variants reported have been experimentally shown to be dominant negative (DN), and it has been recently suggested that eight out-of-frame variants operate by haploinsufficiency. We experimentally tested these 143 variants, 7 novel out-of-frame variants found in HIES patients, and other STAT3 variants from the general population. Strikingly, all 15 out-of-frame variants were DN via their encoded (1) truncated proteins, (2) neoproteins generated from a translation reinitiation codon, and (3) isoforms from alternative transcripts or a combination thereof. Moreover, 128 of the 135 in-frame variants (95%) were also DN. The patients carrying the seven non-DN STAT3 in-frame variants have not been studied for other genetic etiologies. Finally, none of the variants from the general population tested, including an out-of-frame variant, were DN. Overall, our findings show that heterozygous STAT3 variants, whether in or out of frame, underlie AD-HIES through negative dominance rather than haploinsufficiency.
Open Access
Inborn errors of OAS–RNase L in SARS-CoV-2–related multisystem inflammatory syndrome in children
(American Association for the Advancement of Science (AAAS), 2022-12-20) Lee, D.; Pen, J. L.; Yatim, A.; Dong, B.; Aquino, Y.; Ogishi, M.; Pescarmona, R.; Talouarn, E.; Rinchai, D.; Zhang, P.; Perret, M.; Liu, Z.; Jordan, L.; Bozdemir, S. E.; Bayhan, G. I.; Beaufils, C.; Bizien, L.; Bisiaux, A.; Lei, W.; Hasan, M.; Chen, J.; Gaughan, C.; Asthana, A.; Libri, V.; Luna, Joseph M.; Jaffré, Fabrice; Hoffmann, H.; Michailidis, E.; Moreews, M.; Seeleuthner, Y.; Bilguvar, K.; Mane, S.; Flores, C.; Zhang, Y.; Arias, A. A.; Bailey, R.; Schlüter, A.; Milisavljevic, B.; Bigio, B.; Voyer, T. L.; Materna, M.; Gervais, A.; Moncada-Velez, M.; Pala, F.; Lazarov, T.; Levy, R.; Neehus, A.; Rosain, J.; Peel, J.; Chan, Y.; Morin, M.; Pino-Ramirez, R. M.; Belkaya, Serkan; Lorenzo, L.; Anton, J.; Delafontaine, S.; Toubiana, J.; Bajolle, F.; Fumadó, V.; DeDiego, M. L.; Fidouh, N.; Rozenberg, F.; Pérez-Tur, J.; Chen, S.; Evans, T.; Geissmann, F.; Lebon, P.; Weiss, S. R.; Bonnet, D.; Duval, X.; Cohort§, C.; Effort, C.; Pan-Hammarström, Q.; Planas, A. M.; Meyts, I.; Haerynck, F.; Pujol, A.; Sancho-Shimizu, V.; Dalgard, C.; Bustamante, J.; Puel, A.; Boisson-Dupuis, S.; Boisson, B.; Maniatis, T.; Zhang, Q.; Bastard, P.; Notarangelo, L.; Béziat, V.; Diego, R.; Rodriguez-Gallego, C.; Su, H. C.; Lifton, R. P.; Jouanguy, E.; Cobat, A.; Alsina, L.; Keles, S.; Haddad, E.; Abel, L.; Belot, A.; Quintana-Murci, L.; Rice, C. M.; Silverman, R. H.; Zhang, S.; Casanova, J.
Multisystem inflammatory syndrome in children (MIS-C) is a rare and severe condition that follows benign COVID-19. We report autosomal recessive deficiencies of OAS1, OAS2, or RNASEL in five unrelated children with MIS-C. The cytosolic double-stranded RNA (dsRNA)-sensing OAS1 and OAS2 generate 2'-5'-linked oligoadenylates (2-5A) that activate the single-stranded RNA-degrading ribonuclease L (RNase L). Monocytic cell lines and primary myeloid cells with OAS1, OAS2, or RNase L deficiencies produce excessive amounts of inflammatory cytokines upon dsRNA or severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) stimulation. Exogenous 2-5A suppresses cytokine production in OAS1-deficient but not RNase L-deficient cells. Cytokine production in RNase L-deficient cells is impaired by MDA5 or RIG-I deficiency and abolished by mitochondrial antiviral-signaling protein (MAVS) deficiency. Recessive OAS-RNase L deficiencies in these patients unleash the production of SARS-CoV-2-triggered, MAVS-mediated inflammatory cytokines by mononuclear phagocytes, thereby underlying MIS-C.
Open Access
Inborn errors of type I IFN immunity in patients with life-threatening COVID-19
(American Association for the Advancement of Science, 2020) Zhang, Q.; Liu, Z.; Moncada-Velez, M.; Chen, J.; Ogishi, M.; Bigio, B.; Yang, R.; Arias, A. A.; Zhou, Q.; Han, J. E.; Özçelik, Tayfun; Uğurbil, A. C.; Zhang, P.; Rapaport, F.; Li, J.; Spaan, A. N.
Clinical outcomes of human severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection range from silent infection to lethal coronavirus disease 2019 (COVID-19). Epidemiological studies have identified three risk factors for severe disease: being male, being elderly, and having other medical conditions. However, interindividual clinical variability remains huge in each demographic category. Discovering the root cause and detailed molecular, cellular, and tissue- and body-levelmechanismsunderlying life-threatening COVID-19 is of the utmost biological and medical importance.
Open Access
Magneto-optical studies of CdSe/CdMnS/CdS core/multi-shell colloidal nanoplatelets
(SPIE, 2016) Petrou, A.; Scrace, T. A.; Murphy, J. R.; Zhang, P.; Norden, T.; Zhang, T.; Thomay, T.; Cartwright, A. N.; Delikanlı, Savaş; Akgül, Mehmet Zafer; Demir, Hilmi Volkan
We studied the photoluminescence (PL)) from CdSe/CdMnS/CdS core/multi-shell colloidal nanoplatelets, a versatile platform to study the interplay of optical properties and nanomagnetism. The photoluminescence (PL) exhibits σ+ polarization in the applied magnetic field. Our measurement detects the presence of even a single magnetic monolayer shell. The PLL consists of a higher and a lower energy component; the latter exhibits a circular polarization peak. The time-resolved PL (trPL) shows a red shift as function of time delay. At early (later) times the trPL spectra coincide with the high (low) energy PL component. A model is proposed to interpret these results.
Open Access
Mn2+-doped CdSe/CdS core/multishell colloidal quantum wells enabling tunable carrier-dopant exchange interactions
(American Chemical Society, 2015) Delikanlı, S.; Akgül, M. Z.; Murphy, J. R.; Barman, B.; Tsai, Y.; Scrace, T.; Zhang, P.; Bozok, B.; Hernández-Martínez, P.L.; Christodoulides, J.; Cartwright, A. N.; Petrou, A.; Demir, Hilmi Volkan
In this work, we report the manifestations of carrier-dopant exchange interactions in colloidal Mn2+-doped CdSe/CdS core/multishell quantum wells. The carrier-magnetic ion exchange interaction effects are tunable through wave function engineering. In our quantum well heterostructures, manganese was incorporated by growing a Cd0.985Mn0.015S monolayer shell on undoped CdSe nanoplatelets using the colloidal atomic layer deposition technique. Unlike previously synthesized Mn2+-doped colloidal nanostructures, the location of the Mn ions was controlled with atomic layer precision in our heterostructures. This is realized by controlling the spatial overlap between the carrier wave functions with the manganese ions by adjusting the location, composition, and number of the CdSe, Cd1-xMnxS, and CdS layers. The photoluminescence quantum yield of our magnetic heterostructures was found to be as high as 20% at room temperature with a narrow photoluminescence bandwidth of ∼22 nm. Our colloidal quantum wells, which exhibit magneto-optical properties analogous to those of epitaxially grown quantum wells, offer new opportunities for solution-processed spin-based semiconductor devices. © 2015 American Chemical Society.
Open Access
Time resolved photoluminescence study of magnetic CdSe/CdMnS/CdS core/multi-shell nanoplatelets
(SPIE, 2017) Murphy, J. R.; Delikanlı, Savaş; Zhang, T.; Scrace, T. A.; Zhang, P.; Norden, T.; Thomay, T.; Cartwright, A. N.; Demir, Himli Volkan; Petrou, A.
Colloidal semiconductor nanoplatelets (NPLs) are quasi 2D-nanostructures that are grown and processed inexpensively using a solution based method and thus have recently attracted considerable attention. We observe two features in the photoluminescence spectrum, suggesting two possible recombination channels. Their intensity ratio varies with temperature and two distinct temperature regions are identified; a low temperature region (10K < T < 90K) and a high temperature region (90K < T < 200K). This ratio increases with increasing temperature, suggesting that one recombination channel involves holes that are weakly localized with a localization energy of 0.043meV. A possible origin of these localized states are energy-variations in the xy-plane of the nanoplatelet. The presence of positive photoluminescence circular polarization in the magnetically-doped core/multi-shell NPLs indicates a hole-dopant exchange interaction and therefore the incorporated magnetic Manganese ions act as a marker that determines the location of the localized hole states.1 Time-resolved measurements show two distinct timescales (τfast and τslow) that can be modeled using a rate equation model. We identify these timescales as closely related to the corresponding recombination times for the channels. The stronger hole localization of one of these channels leads to a decreased electron-hole wave function overlap and thus a decreased oscillator strength and an increased lifetime. We show that we can model and understand the magnetic interaction of doped 2D-colloidal nanoplatelets which opens a pathway to solution processable spin controllable light sources. Copyright © 2017 SPIE.
Open Access
Time-resolved photoluminescence study of CdSe/CdMnS/CdS core/multi-shell nanoplatelets
(American Institute of Physics Inc., 2016) Murphy, J. R.; Delikanli S.; Scrace, T.; Zhang, P.; Norden, T.; Thomay, T.; Cartwright, A. N.; Demir, Hilmi Volkan; Petrou, A.
We used photoluminescence spectroscopy to resolve two emission features in CdSe/CdMnS/CdS and CdSe/CdS core/multi-shell nanoplatelet heterostructures. The photoluminescence from the magnetic sample has a positive circular polarization with a maximum centered at the position of the lower energy feature. The higher energy feature has a corresponding signature in the absorption spectrum; this is not the case for the low-energy feature. We have also studied the temporal evolution of these features using a pulsed-excitation/time-resolved photoluminescence technique to investigate their corresponding recombination channels. A model was used to analyze the temporal dynamics of the photoluminescence which yielded two distinct timescales associated with these recombination channels. The above results indicate that the low-energy feature is associated with recombination of electrons with holes localized at the core/shell interfaces; the high-energy feature, on the other hand, is excitonic in nature with the holes confined within the CdSe cores.
Open Access
X-linked recessive TLR7 deficiency in ~1% of men under 60 years old with life-threatening COVID-19
(American Association for the Advancement of Science (AAAS), 2021-08-20) Asano, T.; Boisson, B.; Onodi, F.; Matuozzo, D.; Moncada-Velez, M.; Renkilaraj, M. R. L. M.; Zhang, P.; Meertens, L.; Bolze, A.; Materna, M.; Korniotis, S.; Gervais, A.; Talouarn, E.; Bigio, B.; Seeleuthner, Y.; Bilguvar, K.; Zhang, Y.; Neehus, AL.; Ogishi, M.; Pelham, SJ.; Le Voyer, T.; Rosain, J.; Philippot, Q.; Soler-Palacin, P.; Colobran, R.; Martin-Nalda, A.; Riviere, J. G.; Tandjaoui-Lambiotte, Y.; Chaibi, K.; Shahrooei, M.; Darazam, I. A.; Olyaei, NA.; Mansouri, D.; Palabiyik, F.; Özçelik, Tayfun; Novelli, G.; Novelli, A.; Casari, G.; Aiuti, A.; Carrera, P.; Bondesan, S.; Barzaghi, F.; Rovere-Querini, P.; Tresoldi, C.; Franco, J. L.; Rojas, J.; Reyes, LF.; Bustos, IG.; Arias, AA.; Morelle, G.; Kyheng, C.; Troya, J.; Planas-Serra, L.; Schluter, A.; Gut, M.; Pujol, A.; Allende, L. M.; Rodriguez-Gallego, C.; Flores, C.; Cabrera-Marante, O.; Pleguezuelo, DE.; de Diego, R. P.; Keles, S.; Aytekin, G.; Akcan, O. M.; Bryceson, Y. T.; Bergman, P.; Brodin, P.; Smole, D.; Smith, C. I. E.; Norlin, A. C.; Campbell, T. M.; Covill, LE.; Hammarstrom, L.; Pan-Hammarstrom, Q.; Abolhassani, H.; Mane, S.; Marr, N.; Ata, M.; Al Ali, F.; Khan, T.; Spaan, A. N.; Dalgard, C. L.; Bonfanti, P.; Biondi, A.; Tubiana, S.; Burdet, C.; Nussbaum, R.; Kahn-Kirby, A.; Snow, AL.; Bustamante, J.; Puel, A.; Boisson-Dupuis, S.; Zhang, S. Y.; Beziat, V.; Lifton, R. P.; Bastard, P.; Notarangelo, L. D.; Abel, L.; Su, H. C.; Jouanguy, E.; Amara, A.; Soumelis, V.; Cobat, A.; Zhang, Q.; Casanova, J. L.
Autosomal inborn errors of type I IFN immunity and autoantibodies against these cytokines underlie at least 10% of critical COVID-19 pneumonia cases. We report very rare, biochemically deleterious X-linked TLR7 variants in 16 unrelated male individuals aged 7 to 71 years (mean, 36.7 years) from a cohort of 1202 male patients aged 0.5 to 99 years (mean, 52.9 years) with unexplained critical COVID-19 pneumonia. None of the 331 asymptomatically or mildly infected male individuals aged 1.3 to 102 years (mean, 38.7 years) tested carry such TLR7 variants (P = 3.5 × 10−5). The phenotypes of five hemizygous relatives of index cases infected with SARS-CoV-2 include asymptomatic or mild infection (n = 2) or moderate (n = 1), severe (n = 1), or critical (n = 1) pneumonia. Two patients from a cohort of 262 male patients with severe COVID-19 pneumonia (mean, 51.0 years) are hemizygous for a deleterious TLR7 variant. The cumulative allele frequency for deleterious TLR7 variants in the male general population is <6.5 × 10−4. We show that blood B cell lines and myeloid cell subsets from the patients do not respond to TLR7 stimulation, a phenotype rescued by wild-type TLR7. The patients’ blood plasmacytoid dendritic cells (pDCs) produce low levels of type I IFNs in response to SARS-CoV-2. Overall, X-linked recessive TLR7 deficiency is a highly penetrant genetic etiology of critical COVID-19 pneumonia, in about 1.8% of male patients below the age of 60 years. Human TLR7 and pDCs are essential for protective type I IFN immunity against SARS-CoV-2 in the respiratory tract.