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Amplification-free and direct fluorometric determination of telomerase activity in cell lysates using chimeric DNA-templated silver nanoclusters
摘要： A fluorogenic probe has been developed for determination of telomerase activity using chimeric DNA-templated silver nanoclusters (AgNCs). The formation of AgNCs was investigated before (route A) and after (route B) telomerase elongation reaction. Both routes caused selective quenching of the yellow emission of the AgNCs (best measured at excitation/emission wavelength of 470/557 nm) in telomerase-positive samples. The quenching mechanism was studied using synthetically elongated DNA to mimic the telomerase-catalyzed elongation. The findings show that quenching is due to the formation of parallel G-quadruplexes with a –TTA– loop in the telomerase elongated products. The assay was validated using different cancer cell extracts, with intra- and interassay coefficients of variations of <9.8%. The limits of detection for MCF7, RPMI 2650 and HT29 cell lines are 15, 22 and 39 cells/μL. This represents a distinct improvement over the existing telomeric repeat amplification protocol (TRAP) assay in terms of time, sensitivity and cost.
关键词： Biomarker,Telomers,HT29,Biosensor,G-quadruplex,MCF7,AgNCs,TRAP,RPMI 2650,Cancer probe
更新于2025-09-23 15:23:52
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Thermoluminescent behavior of UV and γ rays irradiated Eu2+ and Er3+doped silicate phosphors
摘要： This paper reports the structural, morphological and thermoluminescent studies of Eu2+ and Er3+ ions activated ASiO3 (A= Ca, Ba, Sr) phosphors synthesized via conventional solid state reaction method. The impurity ions concentration of both Eu2+ and Er3+ ions varies from 0 mol% to 1 mol%. The study of crystallographic traits of the synthesized phosphors is done by Powder X-Ray Diffraction (PXRD) analysis. The crystalline nature, phase purity and appreciable homogeneity of the synthesized phosphors were confirmed by this study. The distinct morphological and topographical features were studied through Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM). The thermoluminescent (TL) behavior of ultraviolet (UV) irradiated and gamma irradiated ASiO3:Eu2+, Er3+ (A= Ca, Ba, Sr) phosphors were studied here and the various kinetic parameters were estimated by Computerised glow curve deconvolution (CGCD) technique and peak shape method. The UV and gamma irradiated phosphors exhibit second order kinetics. The high values of activation energy (~ 3 eV) confirm the trapping of electrons in deep trap centers. The incorporation of doping ions into the host lattice causes non-valence substitutions at the substitutional sites. This increases the number of defects and vacancies in the phosphors and more trap centers were generated. The increased TL intensity and high temperature glow peaks confirm the same. The synthesized phosphors show enhanced TL characteristics, efficient trapping mechanism and low fading effects. These characteristics confirm the suitability of the synthesized phosphors for TL mapping and sensing applications.
关键词： Alkaline earth silicates,Thermoluminscence,Activation energy,Trap depth,Order of kinetics.
更新于2025-09-23 15:23:52
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Correlation of afterglow, trap states and site preference in RE2O3:1%Eu (RE=Lu, Y, Sc) single crystal scintillators
摘要： RE2O3:1%Eu (RE=Lu, Y, Sc) single crystals were grown by the optical floating zone method. Correlated measurements of afterglow curves, thermoluminescence, photoluminescence decay, and radioluminescence curves were performed. It is found that the afterglow intensity of Sc2O3:Eu is much lower than the other two compounds and Y2O3:Eu presents a slightly lower afterglow intensity than Lu2O3:Eu. It is discussed in the light of the influence of trap states and site preference in the RE2O3:Eu. The afterglow difference between Sc2O3:Eu and other two compounds mainly comes from the disappearance of Schottky defect in Sc2O3:Eu. While the afterglow difference between Y2O3:Eu and Lu2O3:Eu probably ascribes to the lower S6 site ratio in Y2O3:Eu. Their photoluminescence and other radioluminescence properties were also measured and compared.
关键词： afterglow,trap state,RE2O3:Eu,site preference
更新于2025-09-23 15:23:52
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Critical impact of gate dielectric interfaces on the trap states and cumulative charge of high-performance organic thin field transistors
摘要： In the operation of OFETs, the electrical properties are strongly dependent on the merits of the constituting layers and the formed interfaces. Here we study the trap states variations at the interface between the organic semiconductor pentacene and polymer insulators. With ZrO2 dielectric modified by polymers and find a 10 × decrease in the density of trap states at the semiconductor/insulator interface, bring about the charge carrier mobility increase from 0.058 cm2/Vs to 0.335 cm2/Vs. In addition, when compare to the thicker films at the same applied gate voltage, the thinner film would lead to enhanced coupling capability and more charges cumulative cumulated at the channel region, which is pivotal for optimizing the performance of OFETs. The results prove that the property of the insulator layer could impact largely on the device performance.
关键词： Organic thin film transistor,Cumulative charge,Insulator/semiconductor interface,Trap states
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE International Power Electronics and Application Conference and Exposition (PEAC) - Shenzhen, China (2018.11.4-2018.11.7)] 2018 IEEE International Power Electronics and Application Conference and Exposition (PEAC) - Investigation of Temperature-Dependent Electrical Behavior and Trap Effect in AlGaN/GaN HEMT
摘要： Temperature-dependent electrical behavior and trap effect in AlGaN/GaN high-electron mobility transistors (HEMT) were investigated at temperatures ranging from 25°C to 125°C. The experiment results show that transfer curves negatively shift and transconductance degrades with the increase in temperature at DC and pulsed conditions, meanwhile, gate leakage current increases significantly. Besides, the shift variation of pulsed transfer curves becomes larger at the elevated temperature and static bias states. This mechanism could be attributed to the enhancement of electron-assisted tunneling ability and easily escaping from the traps for trapped electrons at higher temperature. These traps were confirmed on the base of low frequency noise technique under different temperatures, and the extracted activation energy is 0.521eV for the present devices. The above results may provide useful guidance for design and application of the AlGaN/GaN HEMT.
关键词： Trap Effect,GaN,HEMT,Low Frequency Noise,Temperature
更新于2025-09-23 15:23:52
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A cryogenic cylindrical ion trap velocity map imaging spectrometer
摘要： A cryogenic cylindrical ion trap velocity map imaging spectrometer has been developed to study photodissociation spectroscopy and dynamics of gaseous molecular ions and ionic complexes. A cylindrical ion trap made of oxygen-free copper is cryogenically cooled down to ～7 K by using a closed cycle helium refrigerator and is coupled to a velocity map imaging (VMI) spectrometer. The cold trap is used to cool down the internal temperature of mass selected ions and to reduce the velocity spread of ions after extraction from the trap. For CO2+ ions, a rotational temperature of ～12 K is estimated from the recorded [1 + 1] two-photon dissociation spectrum, and populations in spin-orbit excited X2Πg,1/2 and vibrationally excited states of CO2+ are found to be non-detectable, indicating an efficient internal cooling of the trapped ions. Based on the time-of-flight peak profile and the image of N3+ ions, the velocity spread of the ions extracted from the trap, both radially and axially, is interpreted as approximately ±25 m/s. An experimental image of fragmented Ar+ from 307 nm photodissociation of Ar2+ shows that, benefiting from the well-confined velocity spread of the cold Ar2+ ions, a VMI resolution of Δv/v ～ 2.2% has been obtained. The current instrument resolution is mainly limited by the residual radial speed spread of the parent ions after extraction from the trap.
关键词： cryogenic ion trap,velocity map imaging,ion cooling,photodissociation,spectroscopy
更新于2025-09-23 15:23:52
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Use of Camera Traps Provides Insight into the Feeding Ecology of Red Foxes (<i>Vulpes vulpes</i>)
摘要： Red Foxes (Vulpes vulpes) often carry food items to caching sites and while making provisioning trips to litters. This behaviour provides opportunities to use camera traps to record Red Foxes carrying food that is likely prey. As part of a larger study using camera-trap surveys to monitor carnivore populations at Great Swamp National Wildlife Refuge, New Jersey, our cameras also recorded Red Foxes carrying food items allowing us to gain insight into the feeding ecology of this predator. Camera traps documented Red Foxes carrying food 71 times; items included mammals (78.9%), birds (19.7%), and fish (1.4%). Small mammals (unknown rodent or soricid species [23.9%] and voles [Microtus or Clethrionomys spp.; 5.6%]) were the most common groups of food items and Muskrat (Ondatra zibethicus; 15.5%) was the most common food item identified to species. Our surveys corroborate traditional diet assessments (e.g., scat analysis) of Red Foxes in North America, identifying them as a generalist forager that typically consumes smaller mammals. We also highlight the potential to apply camera trapping as a supplemental technique for gaining additional insight into the feeding ecology of this predator.
关键词： Vulpes vulpes,Great Swamp National Wildlife Refuge,prey,Red Fox,diet,Camera trap
更新于2025-09-23 15:22:29
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Shallow and deep trap levels in X-ray irradiated β-Ga2O3: Mg
摘要： The results of the investigation of thermostimulated luminescence (TSL) and photoconductivity (PC) of the X-ray irradiated undoped and Mg2+ doped β-Ga2O3 single crystals are presented. Three low-temperature peaks at 116 K, 147 K and 165 K are observed on the TSL glow curves of undoped crystals. The high-temperature TSL peaks at 354 K and 385 K are dominant in Mg2+ doped crystals. The correlation between doping with Mg2+ ions and the local energy levels of the intrinsic structural defects of β-Ga2O3, which are responsible for the TSL peaks and PC, is established. The nature of TSL peaks and the appropriate photoconductivity excitation bands are discussed.
关键词： Photoconductivity,β-Ga2O3,Single crystal,Activation energy,Trap levels,Thermostimulated luminescence
更新于2025-09-23 15:22:29
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Investigation of Trap-Induced Threshold Voltage Instability in GaN-on-Si MISHEMTs
摘要： It is shown that an EC–0.90 eV trap in commercial AlGaN/GaN MISHEMTs grown on a Si (111) substrate is responsible for a ?1.8-V threshold voltage (VT) instability using a combination of defect spectroscopy and double-pulsed current–voltage measurements. The EC ? 0.90 eV trap is located in the GaN buffer and is emptied by high drain biases in pinch-off, which raises the trap above the Fermi level in the GaN buffer. This trap also exhibits both fast and slow recovery processes that are explained by the availability of free electrons throughout the depth of the GaN buffer and the trapping process that depletes the free electron concentration. TCAD modeling is used to demonstrate this process and also to show why there is not a significant increase in buffer leakage current after the large negative VT shift due to this trap. This demonstrates that optimizing buffer designs are critical for ideal device performance.
关键词： deep-level transient spectroscopy (DLTS),isothermal,GaN-on-Si,threshold voltage instability,metal-insulator-semiconductor high electron mobility transistors (MISHEMTs),Capture process,trap
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE 2nd International Conference on Dielectrics (ICD) - Budapest (2018.7.1-2018.7.5)] 2018 IEEE 2nd International Conference on Dielectrics (ICD) - Improving Surface flashover Performance of LDPE by Dopamine Based on Bionic Technology
摘要： In this paper, dc vacuum surface flashover properties of low density polyethylene (LDPE) film covered with dopamine (Dp)-silver (Ag)-Dopamine (Dp) sandwich structure on the surface by immersing LDPE in dopamine solution(6h), silver nitrate (0.5h, 1h, 2h, 4h) and dopamine (24h) solution in order was researched. Scanning electron microscopic (SEM), surface potential decay (SPD) and Keithley 6517B were used as characterization methods to evaluate surface morphology, surface trap distribution and surface conductivity separately. These parameters may reveal the influence mechanism of Dp-Ag-Dp sandwich structure on samples surface. SEM images shows that nano-Ag particles attaching on the surface of samples and their size and quantity become larger with silver nitrate solution immersing time prolonging. SPD results indicates that both shallow and deep trap depth move to the deeper direction with increasing modification time, while shallow trap and deep trap density decreases first and then increases with the increase of treating time. Surface conductivity enlarges over silver nitrate processing time. For dc vacuum surface flashover voltage, the results presents that its value increases with silver nitrate treatment time when the samples were soaked in silver nitrate solution for less than 2h. It can be concluded that by modifying surface parameters like trap distribution and surface conductivity covering LDPE film surface with dopamine-silver-dopamine sandwich structure can change dc vacuum surface flashover performance.
关键词： trap distribution,dc surface flashover,dopamine
更新于2025-09-23 15:22:29