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"Timing gate"

Mrwan Alayed, M Jamal Deen
Diffuse optical spectroscopy (DOS) and diffuse optical imaging (DOI) are emerging non-invasive imaging modalities that have wide spread potential applications in many fields, particularly for structural and functional imaging in medicine. In this article, we review time-resolved diffuse optical imaging (TR-DOI) systems using solid-state detectors with a special focus on Single-Photon Avalanche Diodes (SPADs) and Silicon Photomultipliers (SiPMs). These TR-DOI systems can be categorized into two types based on the operation mode of the detector (free-running or time-gated)...
September 14, 2017: Sensors
Dmitry A Kalashnikov, Elizaveta V Melik-Gaykazyan, Alexey A Kalachev, Ye Feng Yu, Arseniy I Kuznetsov, Leonid A Krivitsky
Interaction of light with media often occurs with a femtosecond response time. Its measurement by conventional techniques requires the use of femtosecond lasers and sophisticated time-gated optical detection. Here we demonstrate that by exploiting quantum interference of entangled photons it is possible to measure the dephasing time of a resonant media on the femtosecond time scale (down to 100 fs) using accessible continuous wave laser and single-photon counting. We insert a sample in the Hong-Ou-Mandel interferometer and observe the modification of the two-photon interference pattern, which is driven by the coherent response of the medium, determined by the dephasing time...
September 13, 2017: Scientific Reports
Chengzhi Jin, Ruilin Guan, Jingheng Wu, Bo Yuan, Lili Wang, Juanjuan Huang, Hui Wang, Liangnian Ji, Hui Chao
A series of NIR-emitting iridium(iii) complexes were developed for multimodal phosphorescence imaging (NIR imaging, phosphorescence lifetime imaging and time-gated imaging) of mitochondria in living cells, 3D multicellular spheroids (MTCCs) and hippocampus slice under two-photon excitation.
September 6, 2017: Chemical Communications: Chem Comm
Bogdan Cojocaru, Daniel Avram, Vadim Kessler, Vasile Parvulescu, Gulaim Seisenbaeva, Carmen Tiseanu
Despite considerable research, the location of an aliovalent dopant into SnO2 nanoparticles is far to be clarified. The aim of the present study on trivalent lanthanide doped SnO2 is to differentiate between substitutional versus interstitial and surface versus bulk doping, delineate the bulk and surface defects induced by doping and establish an intrinsic dopant distribution. We evidence for the first time a complex distribution of intrinsic nature composed of substitutional isolated, substitutional associates with defects as well as surface centers...
August 29, 2017: Scientific Reports
Tianlie Luo, Jingwen Chen, Bo Song, Hua Ma, Zhiqiang Fu, Willie J G M Peijnenburg
Singlet oxygen ((1)O2) can be photogenerated by photoactive xenobiotics and is capable of causing adverse effects due to its electrophilicity and its high reactivity with biological molecules. Detection of the production and distribution of (1)O2 in living organisms is therefore of great importance. In this study, a luminescent probe ATTA-Eu(3+) combined with time-gated luminescence imaging was adopted to detect the distribution and temporal variation of (1)O2 photoinduced by fluoroquinolone antibiotics and carboxylated/aminated graphenes in Daphnia magna...
July 29, 2017: Aquatic Toxicology
Zhiying Feng, Peng Tao, Liang Zou, Pengli Gao, Yuan Liu, Xing Liu, Hua Wang, Shujuan Liu, Qingchen Dong, Jie Li, Bingshe Xu, Wei Huang, Wai-Yeung Wong, Qiang Zhao
Real-time monitoring of the contents of molecular oxygen (O2) in tumor cells is of great significance in early diagnosis of cancer. At the same time, the photodynamic therapy (PDT) could be realized by highly toxic singlet oxygen ((1)O2) generated in situ during the O2 sensing, making it one of the most promising methods for cancer therapy. Herein, the iridium(III) complex cored hyperbranched phosphorescent conjugated polymer dots with the negative charges for hypoxia imaging and highly efficient PDT was rationally designed and synthesized...
August 30, 2017: ACS Applied Materials & Interfaces
Kristian J Sexton, Yan Zhao, Scott C Davis, Shudong Jiang, Brian W Pogue
The design of fluorescence imaging instruments for surgical guidance is rapidly evolving, and a key issue is to efficiently capture signals with high ambient room lighting. Here, we introduce a novel time-gated approach to fluorescence imaging synchronizing acquisition to the 120 Hz light of the room, with pulsed LED excitation and gated ICCD detection. It is shown that under bright ambient room light this technique allows for the detection of physiologically relevant nanomolar fluorophore concentrations, and in particular reduces the light fluctuations present from the room lights, making low concentration measurements more reliable...
May 1, 2017: Biomedical Optics Express
Jason T Sengel, Mark I Wallace
Electroporation is a common tool for gene transfection, tumour ablation, sterilization and drug delivery. Using experimental methods, we explore the temperature dependence of electropore formation in a model membrane system (droplet-interface bilayers), using optical single-channel recording to image the real-time gating of individual electropores. We investigate the influence of the agarose substrate on electropores formed in this system. Furthermore, by examining the temperature-dependent kinetics of pore opening and closure we are able to estimate a barrier to pore opening in 1,2-diphytanoyl-sn-glycero-3-phosphocholine (DPhPC) membranes to be 25...
August 5, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
J G Porquez, R A Cole, J T Tabarangao, A D Slepkov
We present a simple technique that significantly enhances the interaction of pump pulses with a supercontinuum Stokes generated by a particular nonlinear fiber for time-gated experiments such as coherent anti-Stokes Raman scattering (CARS). The enhancement is achieved through a synchronized power-tuning/time delay scheme that we call spectral surfing. In this Letter, we introduce spectral surfing and demonstrate how its application to an economical CARS hypermicroscopy scheme increases the brightness, contrast, and spectral scanning range, while potentially reducing sample light exposure...
June 15, 2017: Optics Letters
Marco Baù, Marco Ferrari, Vittorio Ferrari
A technique for contactless electromagnetic interrogation of AT-cut quartz piezoelectric resonator sensors is proposed based on a primary coil electromagnetically air-coupled to a secondary coil connected to the electrodes of the resonator. The interrogation technique periodically switches between interleaved excitation and detection phases. During the excitation phase, the resonator is set into vibration by a driving voltage applied to the primary coil, whereas in the detection phase, the excitation signal is turned off and the transient decaying response of the resonator is sensed without contact by measuring the voltage induced back across the primary coil...
June 2, 2017: Sensors
Yusuke Fujii, Taeko Matsuura, Seishin Takao, Yuka Matsuzaki, Takaaki Fujii, Naoki Miyamoto, Kikuo Umegaki, Kentaro Nishioka, Shinichi Shimizu, Hiroki Shirato
For proton spot scanning, use of a real-time-image gating technique incorporating an implanted marker and dual fluoroscopy facilitates mitigation of the dose distribution deterioration caused by interplay effects. This study explored the advantages of using a real-time-image gating technique, with a focus on prostate cancer. Two patient-positioning methods using fiducial markers were compared: (i) patient positioning only before beam delivery, and (ii) patient positioning both before and during beam delivery using a real-time-gating technique...
July 1, 2017: Journal of Radiation Research
Sebastián A Díaz, Guillermo Lasarte Aragonés, Susan Buckhout-White, Xue Qiu, Eunkeu Oh, Kimihiro Susumu, Joseph S Melinger, Alan L Huston, Niko Hildebrandt, Igor L Medintz
Semiconductor nanocrystals or quantum dots (QDs) should act as excellent Förster resonance energy transfer (FRET) acceptors due to their large absorption cross section, tunable emission, and high quantum yields. Engaging this type of FRET can be complicated due to direct excitation of the QD acceptor along with its longer excited-state lifetime. Many cases of QDs acting as energy transfer acceptors are within time-gated FRET from long-lifetime lanthanides, which allow the QDs to decay before observing FRET...
May 3, 2017: Journal of Physical Chemistry Letters
Zhichao Dai, Lu Tian, Bo Song, Xiangli Liu, Jingli Yuan
Rapid, multiplexed, sensitive and specific identification and quantitative detection of nitric oxide (NO) are in great demand in biomedical science. Herein, a novel multifunctional probe based on the intramolecular LRET (luminescence resonance energy transfer) strategy, TRP-NO, was designed for the highly sensitive and selective ratiometric and luminescence lifetime detection of lysosomal NO. Before reaction with NO, the emission of the rhodamine moiety in TRP-NO is switched off, which prevents the LRET process, so that the probe emits only the long-lived Tb(3+) luminescence...
March 1, 2017: Chemical Science
Hua Ma, Bo Song, Yuanxiu Wang, Deyuan Cong, Yufei Jiang, Jingli Yuan
We have developed a ratiometric time-gated luminescence sensory system for in vivo imaging of hypochlorous acid (HClO) by preparing a dual-emissive nanoarchitecture of europium- and terbium-complex-modified silica nanoparticles. The design of this nanoarchitecture is based on our new finding that the strong, long-lived luminescence of the β-diketonate-Eu(3+) complex can be rapidly and selectively quenched by HClO. Therefore, the β-diketonate-Eu(3+) complex was decorated on the surface of the silica nanoparticles for responding to HClO, while a HClO-insensitive luminescent terbium complex was immobilized in the inner solid core of the nanoparticles to serve as an internal standard...
January 1, 2017: Chemical Science
Dian Chen, Qingwen Liu, Zuyuan He
For a distributed fiber-optic vibration sensor (DFVS), the vibration signal extracted from the phase of backscattering has a linear response to the applied vibration, and is more attractive than that from the intensity term. However, the large phase noise at a random weak-fading-point seriously limits the sensor's credibility. In this paper, a novel phase-detection DFVS is developed, which effectively eliminates the weak-fading-point. The relationship between phase noise and the intensity of backscattering is analyzed, and the inner-pulse frequency-division method and rotated-vector-sum method are introduced to effectively suppress phase noise...
April 3, 2017: Optics Express
Xue Qiu, Jiajia Guo, Zongwen Jin, Igor L Medintz, Niko Hildebrandt
Multiplexed photoluminescence (PL) detection plays an important role in chemical and biological sensing. Here, it is shown that time-gated (TG) detection of a single terbium-donor-based Förster resonance energy transfer (FRET) pair can be used to selectively quantify low nanomolar concentrations of multiple DNAs or microRNAs in a single sample. This study demonstrates the applicability of single-TG-FRET-pair multiplexing for molecular (Tb-to-dye) and nanoparticle (Tb-to-quantum-dot) biosensing. Both systems use acceptor-sensitization and donor-quenching for quantifying biomolecular recognition and modification of the donor-acceptor distance for tuning the PL decays...
April 3, 2017: Small
Margaret L Aulsebrook, Suvendu Biswas, Franklin M Leaver, Michael R Grace, Bim Graham, Amy M Barrios, Kellie L Tuck
A bimetallic terbium(iii)/copper(ii) complex (Tb-1·Cu2+) for the time-gated luminescent detection of hydrogen sulfide in aqueous samples is reported. The probe shows excellent selectivity towards HS(-) over various anions and cations, including the ions common to natural waterways and waste water samples, displaying a 73-fold increase in luminescence in the presence of sulfide. The probe exhibits extremely fast reaction times and a low limit of detection (130 nM). The probe was used to quantify sulfide in an industrial "sour water" sample, with the result in excellent agreement with those from two independent assay methods (methylene blue and AzMC)...
March 31, 2017: Chemical Communications: Chem Comm
Long-Jyun Su, Meng-Shiue Wu, Yuen Yung Hui, Be-Ming Chang, Lei Pan, Pei-Chen Hsu, Yit-Tsong Chen, Hong-Nerng Ho, Yen-Hua Huang, Thai-Yen Ling, Hsao-Hsun Hsu, Huan-Cheng Chang
Cell therapy is a promising strategy for the treatment of human diseases. While the first use of cells for therapeutic purposes can be traced to the 19th century, there has been a lack of general and reliable methods to study the biodistribution and associated pharmacokinetics of transplanted cells in various animal models for preclinical evaluation. Here, we present a new platform using albumin-conjugated fluorescent nanodiamonds (FNDs) as biocompatible and photostable labels for quantitative tracking of human placenta choriodecidual membrane-derived mesenchymal stem cells (pcMSCs) in miniature pigs by magnetic modulation...
March 30, 2017: Scientific Reports
Quankun Gao, Wenzhu Zhang, Bo Song, Run Zhang, Weihua Guo, Jingli Yuan
Considering the important roles of biothiols in lysosomes of live organisms, and unique photophysical/photochemical properties of ruthenium(II) complexes, a novel ruthenium(II) complex, Ru-2, has been developed as a molecular probe for phosphorescence and time-gated luminescence assay of biothiols in human sera, live cells, and in vivo. Ru-2 is weakly luminescent due to the effective photoinduced electron transfer (PET) from Ru(II) luminophore to electron acceptor, 2,4-dinitrobenzene-sulfonyl (DNBS). In the presence of biothiols, such as glutathione (GSH), cysteine (Cys), and homocysteine (Hcy), the emission of Ru-2 solution was switched ON, as a result of the cleavage of quencher to form the product, Ru-1...
March 31, 2017: Analytical Chemistry
Stefan Altmann, Max Spielmann, Florian Engel, Rainer Neumann, Steffen Ringhof, Doris Oriwol, Sascha Haertel
The purpose of this study was to quantify the effect of different timing light heights on sprint time and the validity of measurement. Two single beam timing gate systems were used to measure 30-m sprint time (splits at 5 m and 10 m) in 15 healthy and physically active male subjects. System 1 was set up at a height of 0.64 m, system 2 at 0.25 m (initial timing light) and 1.00 m (each following timing light), respectively. Participants performed three valid trials. The recordings of a high-speed video camera were used as a reference...
March 8, 2017: Journal of Strength and Conditioning Research
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