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- 2018
- ac-dc difference
- Thermal transfer standard
- inductive voltage
- uncertainty budget
- pulse-driven ac Josephson voltage standard
- Measurement and Control Technology and Instruments
- National Institute of Metrology
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Quantumness in light harvesting is determined by vibrational dynamics
摘要： We demonstrate for the multi-level spin-boson (MLSB) Hamiltonian, typically used to describe biological light-harvesting, that the distinction between quantum and classical dynamics is determined entirely by the thermal environment. In particular, any MLSB model featuring classical interactions with a classical bath is exactly equivalent in its absorption and energy transfer dynamics to a classical model involving coupled harmonic oscillators. This result holds in the linear response regime for both pulsed and incoherent excitation. In the biological context, this finding highlights the centrality of vibrational dynamics in determining the 'quantumness' of photosynthetic light-harvesting, particularly in the creation of the photosynthetic energy funnel where excitation energy concentrates near the reaction center via a series of downhill energy transfer events. These findings support the idea that this energy funnel is exclusively quantum-mechanical in origin, although it need not rely on entanglement.
关键词： vibrational dynamics,energy transfer,photosynthesis,quantumness,light harvesting,spin-boson model
更新于2025-09-23 15:23:52
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Towards the Development of Photo‐Reactive Ruthenium(II) Complexes Targeting Telomeric G‐Quadruplex DNA
摘要： The design and characterization of new ruthenium(II) complexes aimed at targeting G-quadruplex DNA is reported. Importantly, these complexes are based on oxidizing 1,4,5,8-tetraazaphenanthrene (TAP) ancillary ligands known to favour photo-induced electron transfer (PET) with DNA. The photochemistry of complexes 1–4 has been studied by classical methods, which revealed two of them to be capable of photo-abstracting an electron from guanine. From studies of the interactions with DNA through luminescence, circular dichroism, bio-layer interferometry, and surface plasmon resonance experiments, we have demonstrated the selectivity of these complexes for telomeric G-quadruplex DNA over duplex DNA. Preliminary biological studies of these complexes have been performed: two of them showed remarkable photo-cytotoxicity towards telomerase-negative U2OS osteosarcoma cells, whereas very low mortality was observed in the dark at the same photo-drug concentration.
关键词： ruthenium complexes,photo-electron transfer,photocytotoxicity,G-quadruplexes,DNA structures
更新于2025-09-23 15:23:52
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Effect of H?SO? Solution Treating on the Adhesion, Charge Transfer and Catalytic Performance of Screen‐Printed PEDOT:PSS
摘要： Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) films screen-printed on fluorine-doped tin oxide (FTO) substrates, to improve their charge transfer efficiency. Different H2SO4 solutions including concentrated H2SO4 and H2SO4 diluted with H2O or dimethyl sulfoxide (DMSO) were adopted during the post-treatment. The adhesion of the as-treated films was evaluated by adhesive tape peeling tests, the surface morphology and vertical charge transfer from the films to the substrates were investigated by current-sensing atomic force microscopy, and the catalytic activities toward I3- reduction of PEDOT:PSS films were characterized via electrochemical measurements. It is discovered that selecting proper H2SO4 solutions is crucial to improve the charge transfer efficiency and catalytic performance while maintaining the reliable adhesion of the film on the substrates, and H2SO4/DMSO performs best as the solution for post-treatment. A schematic mechanism was proposed based on different interactions among solution, PEDOT:PSS and the substrate in the case of various post-treatment solutions.
关键词： charge transfer,poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate),screen printing,catalysis,post-treatment
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE 20th International Workshop on Multimedia Signal Processing (MMSP) - Vancouver, BC, Canada (2018.8.29-2018.8.31)] 2018 IEEE 20th International Workshop on Multimedia Signal Processing (MMSP) - Deep Transfer Learning for Hyperspectral Image Classification
摘要： Hyperspectral image (HSI) includes a vast quantities of samples, large number of bands, as well as randomly occurring redundancy. Classifying such complex data is challenging, and the classification performance generally is affected significantly by the amount of labeled training samples. Collecting such labeled training samples is labor and time consuming, motivating the idea of borrowing and reusing labeled samples from other pre-existing related images. Therefore transfer learning, which can mitigate the semantic gap between existing and new HSI, has recently drawn increasing research attention. However, existing transfer learning methods for HSI which concentrated on how to overcome the divergence among images, may neglect the high level latent features during the transfer learning process. In this paper, we present two novel ideas based on this observation. We propose constructing and connecting higher level features for the source and target HSI data, to further overcome the cross-domain disparity. Different from existing methods, no priori knowledge on the target domain is needed for the proposed classification framework, and the proposed framework works for both homogeneous and heterogenous HSI data. Experimental results on real world hyperspectral images indicate the significance of the proposed method in HSI classification.
关键词： supervised classification,salient samples,Hyperspectral image,Transfer learning
更新于2025-09-23 15:23:52
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Band gap analysis of periodic structures based on cell experimental frequency response functions (FRFs)
摘要： An approach is proposed to estimate the transfer function of the periodic structure, which is known as an absorber due to its repetitive cells leading to the band gap phenomenon. The band gap is a frequency range in which vibration will be inhibited. A transfer function is usually performed to gain band gap. Previous scholars regard estimation of the transfer function as a forward problem assuming known cell mass and stiffness matrices. However, the estimation of band gap for irregular or complicated cells is hardly accurate because it is difficult to model the cell exactly. Therefore, we treat the estimation as an inverse problem by employing modal identification and curve fitting. A transfer matrix is then established by parameters identified through modal analysis. Both simulations and experiments have been performed. Some interesting conclusions about the relationship between modal parameters and band gap have been achieved.
关键词： Band gap,Periodic structure,Transfer matrix,Parameter identification,Modal analysis
更新于2025-09-23 15:23:52
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Solar Heterogeneous Photocatalytic Oxidation for Water and Wastewater Treatment: Problems and Challenges
摘要： Solar operation of heterogeneous photocatalytic oxidation reactors is looked at as a sustainable process for water and wastewater treatment, because it does not consume electric power and chemicals. However, there are still problems for technical-scale application. The problems addressed in this article are large area demand, water evaporation from open reactors and lack of simple photocatalyst recovery. An optimum solar reactor type is the parabolic compound collector reactor with borosilicate glass tubes. Challenges for further research are improvement in mass transfer as well as identification of novel photocatalysts which make use also of visible light, are efficient and stable, and are easy to be produced in an economically feasible way. Also the combination of photocatalysts with adsorbents is promising. Although membrane filtration processes have been successfully combined with solar photocatalytic oxidation and represent a safe barrier against spreading photocatalyst nanoparticles into the aquatic environment, more simple and less energy-consuming methods for photocatalyst recovery would be desirable.
关键词： Photocatalyst recovery,Novel photocatalysts,Solar photocatalytic oxidation,Photocatalysis adsorption hybrid process,Mass transfer
更新于2025-09-23 15:23:52
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Self-Luminescing Theranostic Nanoreactors with Intraparticle Relayed Energy Transfer for Tumor Microenvironment Activated Imaging and Photodynamic Therapy
摘要： The low tissue penetration depth of external excitation light severely hinders the sensitivity of fluorescence imaging (FL) and the efficacy of photodynamic therapy (PDT) in vivo; thus, rational theranostic platforms that overcome the light penetration depth limit are urgently needed. To overcome this crucial problem, we designed a self-luminescing nanosystem (denoted POCL) with near-infrared (NIR) light emission and singlet oxygen (1O2) generation abilities utilizing an intraparticle relayed resonance energy transfer strategy. Methods: Bis[3,4,6-trichloro-2-(pentyloxycarbonyl) phenyl] oxalate (CPPO) as a chemical energy source with high reactivity toward H2O2, poly[(9,9’-dioctyl-2,7-divinylene-?uorenylene)-alt-2-methoxy-5-(2-ethyl-hexyloxy)-1,4-phenylene] (PFPV) as a highly efficient chemiluminescence converter, and tetraphenylporphyrin (TPP) as a photosensitizer with NIR emission and 1O2 generation abilities were coencapsulated by self-assembly with poly(ethyleneglycol)-co-poly(caprolactone) (PEG-PCL) and folate-PEG-cholesterol to form the POCL nanoreactor, with folate as the targeting group. A series of in vitro and in vivo analyses, including physical and chemical characterizations, tumor targeting ability, tumor microenvironment activated imaging and photodynamic therapy, as well as biosafety, were systematically investigated to characterize the POCL. Results: The POCL displayed excellent NIR luminescence and 1O2 generation abilities in response to H2O2. Therefore, it could serve as a speci?c H2O2 probe to identify tumors through chemiluminescence imaging and as a chemiluminescence-driven PDT agent for inducing tumor cell apoptosis to inhibit tumor growth due to the abnormal overproduction of H2O2 in the tumor microenvironment. Moreover, the folate ligand on the POCL surface can further improve the accumulation at the tumor site via a receptor-mediated mechanism, thus enhancing tumor imaging and the therapeutic effects both in vitro and in vivo but without any observable systemic toxicity. Conclusion: The nanosystem reported here might serve as a targeted, smart, precise, and noninvasive strategy triggered by the tumor microenvironment rather than by an outside light source for cancer NIR imaging and PDT treatment without limitations on penetration depth.
关键词： chemiluminescent imaging,H2O2,self-luminescing theranostic nanoreactors,intraparticle relayed energy transfer,PDT
更新于2025-09-23 15:23:52
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Entanglement generation between distant parties via disordered spin chains
摘要： We study the emergence of bipartite entanglement between a pair of spins weakly connected to the ends of a linear disordered X Y spin-1/2 channel. We analyze how their concurrence responds to structural and on-site fluctuations embodied by long-range spatially-correlated sequences. We show that the end-to-end entanglement is very robust against disorder and asymmetries in the channel provided that the degree of correlations are strong enough and both entangling parties are tuned accordingly. Our results offer further alternatives in the design of stable quantum communication protocols via imperfect spin channels.
关键词： Quantum entanglement,Quantum state transfer,Anderson localization
更新于2025-09-23 15:23:52
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Photonics of tetramethoxy-1,4-distyrylbenzene
摘要： Photonics of tetramethoxy-1,4-distyrylbenzene in MeCN was studied by absorption, luminescence, and laser kinetic spectroscopies. Photoinduced transformations of the compound in question involve cis—trans-isomerization, intersystem crossing, fast and delayed fluorescence, and electron transfer. The ground-state structure and vibrational spectrum, as well as the energies and structures of excited singlet and triplet states were calculated by the DFT/PBE and TDDFT/PBE0 methods. The assignment of vibronic bands in the absorption spectra was made and the energies of corresponding transitions were calculated.
关键词： triplet state,trans—cis-photoisomerization,electron transfer,delayed fluorescence
更新于2025-09-23 15:23:52
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Mass Spectrometric Imaging Reveals Photocatalytic Degradation Intermediates of Aromatic Organochlorines Resulting from Interfacial Photoelectron Transfer and Hydroxyl Radical Abstraction on Semiconductor Nanoparticles
摘要： Organochlorines are highly persistent and toxic contaminants that are widely distributed and accumulated in various aquatic or soil environments as well as food chains. Heterogeneous photocatalytic degradation of such pollutants by using semiconductor nanoparticles has been recognized as one of the effective purification ways. Understanding of degradation mechanisms and designing of highly efficient semiconductor nanoparticles require structural identification of various degradation intermediates that are difficult to achieve with current spectroscopic techniques. Herein a mass spectrometric approach was developed to tackle interfacial photoelectron transfer and hydroxyl radical abstraction on different semiconductor nanoparticles. Chlorobenzenes (including hexachlorobenzene and chlorothalonil) adsorbed on the surfaces of nanoparticles were found to instantly undergo dechlorination and ring dissociation through photoelectron capture dissociation and abstraction of a chlorine atom from aromatic C-Cl bond by hydroxyl radicals. Different intermediates have been unambiguously identified with experimental evidences provided by a Q-TOF mass spectrometer. It has been demonstrated that both electron density around atoms and steric effects of side chains contribute to the site selectivity for photoelectron capture and hydroxyl radical abstraction. But the energies needed for chemical bond cleavages and the stabilization of acquired charges play important roles in degradation efficiency. By using mass spectrometric imaging, photocatalytic differences of different semiconductor nanoparticles have been revealed.
关键词： Photoelectron Capture Dissociation,Interfacial Photoelectron Transfer,Chlorobenzenes,Mass Spectrometry,Hydroxyl Radical
更新于2025-09-23 15:23:52