A high precision calibration of the nonlinearity in the energy response of the Daya Bay Reactor Neutrino Experiment’s antineutrino detectors is presented in detail. The energy nonlinearity originates ...from the particle-dependent light yield of the scintillator and charge-dependent electronics response. The nonlinearity model is constrained by γ calibration points from deployed and naturally occurring radioactive sources, the β spectrum from 12B decays, and a direct measurement of the electronics nonlinearity with a new flash analog-to-digital converter readout system. Less than 0.5% uncertainty in the energy nonlinearity calibration is achieved for positrons of kinetic energies greater than 1 MeV.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Porous perovskite lanthanum ferrites (LaFeO3) powders were synthesized under the different pH value by sol-gel technique and self-propagating combustion method. After the characterization with XRD, ...SEM, VSM, nitrogen adsorption-desorption isotherm and UV–Vis spectroscopy, the magnetic properties, photocatalytic activity and gas-sensing performance are discussed in detail. All LaFeO3 samples exhibit ferromagnetism for the spin mismatch due to oxygen vacancies. LaFeO3 powders present the good photocatalytic performance to MB and could be easily separated by magnetic separation technique after photocatalysis. Furthermore, the LaFeO3 gas sensors exhibited the considerable sensitivity to ethanol gas. Among all samples, LF-1 (LaFeO3 powders prepared at pH = 1) present the highest removal rate of MB (68%), the largest saturation magnetization (4.57 emu/g) and the best gas response to ethanol. The highest response for LF-1 sensor reaches (263.4) at the optimized operating temperature of 250 °C to 100 ppm ethanol gas, which should be attributed to the higher oxygen vacancies.
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•Porous LaFeO3 powders were prepared by sol-gel method.•Samples present the high surface area due to porous microstructures.•Ferromagnetism of LaFeO3 powders results from oxygen vacancies.•The lower bandgap lead to the highest photocatalytic activity of LF-1 to MB.•Surface area, bandgap and oxygen vacancies greatly affects the gas-sensing performance.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Brain inflammation is a primary pathological driving force of many neurodegenerative disorders. In the destructive process, pro-inflammatory cytokines (IL-1β and TNF-α), are robustly released, ...affecting normal neural progenitor cell (NPC) differentiation, and resulting in a vast number of astrocytes and a diminished neural population. A counteractive mechanism is still unknown. In this study, we have identified a link between brain inflammation and the signal transducer and activator of transcription 3 (STAT3) pathway: IL-1β and TNF-α induce STAT3 activation in NPCs. Then to investigate STAT3's effects on NPC fate, we observed that an inhibition of STAT3 expression by siRNA inhibited astrocytic differentiation and increased neuronal differentiation of human NPCs in fetal bovine serum (FBS)-induced astrocyte differentiation condition. Furthermore, STAT3-targeting siRNA abrogated IL-1β and TNF-α-induced astrocyte differentiation and partially restored neuronal differentiation. Elimination of STAT3 expression also countered IL-1β and TNF-α-induced inhibition of proneural bHLH genes, mammalian achaete-schute homologue-1 (Mash1), Neurogenin1 (Ngn1), and Neurogenin2 (Ngn2). These data suggest that a suppression of STAT3 during brain inflammation would inhibit astrogliogenesis and promote neurogenesis. Thus, STAT3 could be a potential target of drug therapy for neurodegenerative disorders.
We present a new determination of the smallest neutrino mixing angle θ_{13} and the mass-squared difference Δm_{32}^{2} using a final sample of 5.55×10^{6} inverse beta-decay (IBD) candidates with ...the final-state neutron captured on gadolinium. This sample is selected from the complete dataset obtained by the Daya Bay reactor neutrino experiment in 3158 days of operation. Compared to the previous Daya Bay results, selection of IBD candidates has been optimized, energy calibration refined, and treatment of backgrounds further improved. The resulting oscillation parameters are sin^{2}2θ_{13}=0.0851±0.0024, Δm_{32}^{2}=(2.466±0.060)×10^{-3} eV^{2} for the normal mass ordering or Δm_{32}^{2}=-(2.571±0.060)×10^{-3} eV^{2} for the inverted mass ordering.
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The growth process is crucial to achieve large-sized and high-quality aluminum nitride (AlN) crystals through the physical vapor transport (PVT) method. To investigate the influence of parameters on ...the growth of AlN crystals, a series of quasi-steady numerical simulations on the temperature distribution, growth rate, and partial pressure of Al vapor inside the growth cell were conducted based on a self-developed finite element mass transfer module in the COMSOL package, which considers the partial pressure of gas phases, for different growth temperatures and crucible positions. The simulation results show that increasing the growth temperature significantly augments the partial pressure of Al vapor and the growth rate in the growth cell. Simultaneously, variation of the crucible position substantially alters the temperature distribution and the transport direction of Al vapor inside the crucible. A novel heat sink on the top of the crucible was designed to impair the phenomenon of uneven crystal growth on the surface of the seed caused by the nonuniform radial temperature distribution. Compared to the original crucible, the radial temperature gradient of the optimized crucible was reduced by 37%, and the uniformity of seed surface growth was improved by 89%. This work guides the design of a novel crystal growth furnace and the preparation of high-quality AlN single crystals by the PVT method.
A novel heat sink at the top of the crucible improves the seed surface growth uniformity by 89%.
A search for a time-varying ν¯e signal was performed with 621 days of data acquired by the Daya Bay Reactor Neutrino Experiment over 704 calendar days. The time spectrum of the measured ν¯e flux ...normalized to its prediction was analyzed with a Lomb-Scargle periodogram, which yielded no significant signal for periods ranging from 2 hours to nearly 2 years. The normalized time spectrum was also fit for a sidereal modulation under the Standard Model Extension (SME) framework to search for Lorentz and CPT violation (LV-CPTV). Limits were obtained for all six flavor pairs e¯μ¯,e¯τ¯, μ¯τ¯, e¯e¯,μ¯μ¯ and τ¯τ¯ by fitting them one at a time, constituting the first experimental constraints on the latter three. Daya Bay’s high statistics and unique layout of multiple directions from three pairs of reactors to three experimental halls allowed the simultaneous constraint of individual SME LV-CPTV coefficients without assuming others contribute negligibly, a first for a neutrino experiment.
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Photodynamic Therapy Dougherty, Thomas J.; Gomer, Charles J.; Jori, Giulio ...
JNCI : Journal of the National Cancer Institute,
06/1998, Volume:
90, Issue:
12
Journal Article
Peer reviewed
Open access
Photodynamic therapy involves administration of a tumorlocalizing photosensitizing agent, which may require metabolic synthesis (i.e., a prodrug), followed by activation of the agent by light of a ...specific wavelength. This therapy results in a sequence of photochemical and photobiologic processes that cause irreversible photodamage to tumor tissues. Results from preclinical and clinical studies conducted worldwide over a 25-year period have established photodynamic therapy as a useful treatment approach for some cancers. Since 1993, regulatory approval for photodynamic therapy involving use of a partially purified, commercially available hematoporphyrin derivative compound (Photofrin®) in patients with early and advanced stage cancer of the lung, digestive tract, and genitourinary tract has been obtained in Canada, The Netherlands, France, Germany, Japan, and the United States. We have attempted to conduct and present a comprehensive review of this rapidly expanding field. Mechanisms of subcellular and tumor localization of photosensitizing agents, as well as of molecular, cellular, and tumor responses associated with photodynamic therapy, are discussed. Technical issues regarding light dosimetry are also considered. J Natl Cancer Inst 1998;90:889-905
A new orthorhombic phase of the multiferroic BiFeO3 has been created via strain engineering by growing it on a NdScO(3)(110)(o) substrate. The tensile-strained orthorhombic BiFeO3 phase is ...ferroelectric and antiferromagnetic at room temperature. A combination of nonlinear optical second harmonic generation and piezoresponse force microscopy revealed that the ferroelectric polarization in the orthorhombic phase is along the in-plane {110}(pc) directions. In addition, the corresponding rotation of the antiferromagnetic axis in this new phase was observed using x-ray linear dichroism.
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