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Early gastric cancer detection in high-risk patients: a multicentre randomised controlled trial on the effect of second-generation narrow band imaging
摘要： Objective early detection of gastric cancer has been the topic of major efforts in high prevalence areas. Whether advanced imaging methods, such as second-generation narrow band imaging (2g- nBi) can improve early detection, is unknown. Design This open-label, randomised, controlled tandem trial was conducted in 13 hospitals. Patients at increased risk for gastric cancer were randomly assigned to primary white light imaging (Wli) followed by secondary 2g- nBi (Wli group: n=2258) and primary 2g- nBi followed by secondary Wli (2g- nBi group: n=2265) performed by the same examiner. suspected early gastric cancer (egc) lesions in both groups were biopsied. Primary endpoint was the rate of egc patients in the primary examination. The main secondary endpoint was the positive predictive value (PPV) for egc in suspicious lesions detected (primary examination). results egcs were found in 44 (1.9%) and 53 (2.3%; p=0.412) patients in the Wli and 2g- nBi groups, respectively, during primary egD. in a post hoc analysis, the overall rate of lesions detected at the second examination was 25% (n=36/145), with no significant differences between groups. PPV for egc in suspicious lesions was 13.5% and 20.9% in the Wli (50/371 target lesions) and 2g- nBi groups (59/282 target lesions), respectively (p=0.015). Conclusion The overall sensitivity of primary endoscopy for the detection of egc in high- risk patients was only 75% and should be improved. 2g- nBi did not increase egc detection rate over conventional Wli. The impact of a slightly better PPV of 2g- nBi has to be evaluated further.
关键词： positive predictive value,narrow band imaging,early gastric cancer,detection rate,white light imaging
更新于2025-09-19 17:13:59
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Numerical Prediction and Experimental Validation of Multiple Phosphor White LED Spectrum
摘要： White LEDs with single phosphor usually have poor color rendering capability. The emission spectra of the blue LED and the yellow phosphor are narrow as compared with the reference light sources. The red light output is particular low. The color of the objects illuminated by such light source appear not accurate nor natural. Though the luminous efficiency is high, such poor color rendering light sources are not suitable for most general lighting applications. To improve the color rendering properties, multiple phosphors with different emission spectra should be used. For instance, a certain amount of red or orange phosphors may be used to mix with yellow phosphor to broaden the overall spectrum. In this paper, a numerical model is proposed to predict the emission spectra of LEDs with multiple phosphors. The model has considered the excitation and emission spectra of the phosphors, the mixing ratio and re-absorption between the phosphors. To validate the model, white light LEDs with multiple phosphors are fabricated. The spectra are measured and compared with the modeling results. It is found that the proposed model can estimate the emission spectra of LEDs with multiple phosphors with a high degree of accuracy.
关键词： Color Rendering,Spectrum Prediction,Phosphor Characterizations,White Light LED,Multiple Phosphors
更新于2025-09-19 17:13:59
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Silica nanoparticles assisted preparation of reddish-yellow emitting Eu2+ activated remote-type CaSrSiO4 phosphor for warm white LED applications
摘要： A reddish-yellow emitting silicate-based remote phosphor has been developed via the wet-solid phase reaction technique. By employing silica nanoparticles (200 nm), Eu2+ doped CaSrSiO4 phosphor was developed and its e?cacy has been examined thoroughly. The developed remote phosphor can get excited over a broad region of the spectrum ranging from ultraviolet to blue (250–500 nm) and as generates a reddish-yellow emission peaked at 580 nm covering a broad range of spectral components (450–800 nm) with a quantum e?ciency of 52%. The thermoluminescence studies of developed remote phosphor exhibit 50% of the stable emission up to 200 °C without any shift in the emission wavelength. The developed remote phosphor was then utilized for the making of a proto-type LED using 450 nm blue-emitting commercial LED. The output emission from the proto-type LED con?rms the production of e?cient warm white light with CCT < 5000 K and CRI > 85.
关键词： Phosphor,LED,Warm white light,Remote phosphor
更新于2025-09-19 17:13:59
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Hue‐ and Chromaticity‐Based Exploration of Surface Complexation‐Induced Tunable Emission from Non‐Luminescent Quantum Dots
摘要： Herein we report the use of a hue parameter of HSV (Hue, Saturation and Value) color space—in combination with chromaticity color coordinates—for exploring the complexation-induced luminescence color changes, ranging from blue to green to yellow to white, from a non-luminescent Fe-doped ZnS quantum dot (QD). Importantly, the surface complexation reaction helped a presynthesized non-luminescent Fe-doped ZnS QD to glow with different luminescence colors (such as blue, cyan, green, greenish-yellow, yellow) by virtue of the formation of various luminescent inorganic complexes (using different external organic ligands), while the simultaneous blue- and yellow-emitting complex formation on the surface of non-luminescent Fe-doped ZnS QD led to the generation of white light emission, with a hue mean value of 85 and a chromaticity of (0.28,0.33). Furthermore, the surface complexation-assisted incorporation of luminescence properties to a non-luminescent QD not only overcomes their restricted luminescence-based applications such as light-emitting, biological and sensing applications but also bring newer avenues towards unravelling the surface chemistry between QDs and inorganic complexes and the advantage of having an inorganic complex with QD for their aforementioned useful applications.
关键词： quantum dots,inorganic complexes,photoluminescence,hue,chromaticity,white light emission
更新于2025-09-19 17:13:59
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Experimental study of the effects of femtosecond laser power on the induced-plasma geometry, supercontinuum white light generation and conical emission in air
摘要： This paper presents the experimental investigation of the changes in the geometrical shape of femtosecond laser-induced plasma in air under different laser power, and its effects on supercontinuum white light generation and conical emission. When a femtosecond laser is focused into a tiny spot in air, optical breakdown of air molecules occurs and this leads to the generation of plasma filament whose geometrical size and shape depend on laser power. This process is then followed by two light-emitting processes, namely supercontinuum white light generation and conical emission, both of which scatter light that reveals the characteristics of the plasma filament. Our experiment shows that the laser-induced plasma becomes thinner and longer at high average laser power but appears thick and round at lower laser power. At higher laser power, conical emission which scatters laser light in the forward direction dominates the scattering process while at lower laser power, it is the scattering of supercontinuum white light in all directions that plays a bigger role. The intricate rainbow-like pattern formed on a white screen located far away in the forward direction reveals sophisticated nonlinear optical processes that take place in conical emission which slowly diminishes as the laser power is gradually reduced.
关键词： Femtosecond laser,conical emission,laser-induced plasma,supercontinuum white light
更新于2025-09-19 17:13:59
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Facile Preparation of Stable Solid-State Carbon Quantum Dots with Multi-Peak Emission
摘要： Aggregation-caused quenching (ACQ) effect, known as the main cause to restrain solid-state luminescence of carbon quantum dots (CQDs), hinders further application of CQDs in white light-emitting diodes (WLED). Here, a complex of CQDs and phthalimide crystals (CQDs/PC) was prepared through a one-step solvothermal method. CQDs/PC prevented CQDs from touching directly by embedding the CQDs in phthalimide crystal matrix in situ, which effectively reduced the ACQ effect. Furthermore, CQDs/PC exhibited multi-peak fluorescence spectra that span the green, yellow and orange spectral regions. Finally, a WLED fabricated based on CQDs/PC achieved a color-rendering index of 82 and a correlated color temperature of 5430 K. This work provides a quick and effective strategy to apply CQDs to WLED.
关键词： solid-state luminescence,multi-peak emission,yellow carbon quantum dots,white light-emitting diode
更新于2025-09-19 17:13:59
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Tunable LED Lighting with Five Channels of RGCWW for High Circadian and Visual Performances
摘要： In this study, red, green, cyan, warm white and cool white (RGCWW) LEDs are individually controlled to simulate dynamic daylight. The spectral power distributions (SPDs) are measured for both the daylight and the mixed white light. The correlated color temperature (CCT), circadian action factor (CAF) curves in the daytime of the mixed white LED almost overlap to those of daylight with a small error of about 1%. The CIE chromaticity coordinates of the mixed white light are distributed along the Planckian locus with a little deviation below 0.003. Also, its color rendering index (CRI) is above 90. The RGCWW five-chip LEDs of high circadian and visual performances will benefit to synchronize circadian rhythm in closed environment during long time without daylight, combined with better mood and alertness. The simulation errors and development trend of the mixed lighting are discussed.
关键词： mixed white light,circadian rhythm,circadian action factor,color rendering index,light emitting diode
更新于2025-09-16 10:30:52
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Pyrene-based hyperbranched porous polymers with doped Ir(piq)2(acac) red emitter for highly efficient white polymer light-emitting diodes
摘要： Here, we designed and prepared a series of hyperbranched porous polymers constructed using fluorene branches and pyrene core, and all hyperbranched porous polymers exhibit intense blue fluorescence, good morphological stability, and high thermal stability. Further, it is found that the aperture sizes for hyperbranched porous polymers can be adjusted by simply changing the content of pyrene and fluorene in the synthesis process. When the feed ratios of pyrene in the total polymers is 15 mol%, the optimized aperture size was obtained, which is slightly larger than the maxlength of complementary red emitter Bis(1-phenylisoquinoline)(acetylacetonate) iridium (III) (Ir(piq)2acac), indicating the Ir(piq)2acac can well distributed in the apertures of hyperbranched porous polymers in co-doped film of Ir(piq)2acac and hyperbranched porous polymers. The fabricated polymer-light-emitting diode (PLED) with such co-doped film as light-emitting layer realizes good white emission with almost equal blue and red emission intensity from hyperbranched porous polymers and Ir(piq)2acac. The balanced electroluminescent (EL) spectra contribute to ideal Commission Internationale de l’Eclairage (CIE) coordinate of (0.326, 0.374) located at white light zone. In addition, the device also achieves high device performance with maximum luminance and current efficiency reaching 5369 cd/m2 and 8.35 cd/A, respectively. We believe that such porous-structure polymers have huge potential applications in the development of highly efficient white PLEDs with reducing production cost.
关键词： White light,Electroluminescence spectra,Polymer light-emitting diodes,Hyperbranched porous polymers
更新于2025-09-16 10:30:52
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Analysis of the Heat Affected Zone and Surface Roughness during Laser Micromachining of Metals
摘要： The current research focuses on the characterization of the produced heat affected zone when laser heats AISI H13 steel, AISI 1045 steel and Ti6Al4V alloy workpieces via finite element simulations and experimental investigation. The surface roughness designedly varies on the surface of the samples and its influence on the absorption of laser light is investigated. Experiments are conducted at 1-4 W laser power and for two scanning speeds of 2 and 100 mm/min. A 3D transient thermo-structural finite element model for a moving Gaussian laser heat source is developed to simulate the micromachining process and predict the depth and width of the heat affected zone. The Johnson-Cook material model that takes into account the effect of plastic strain, strain rate and temperature, along with a fracture model, is adapted to the simulations. A good agreement between the experimental data and the simulation results is found. The depth and width of the heat affected zone strongly depend on the laser parameters and material properties of the irradiated samples. This study constitutes the basis to the optimization and improvement of the laser assisted micromachining process parameters and provides key insights on the roughness-absorptivity relation for the three metallic materials.
关键词： finite element method,heat affecting zone,white-light interferometry,laser heating
更新于2025-09-16 10:30:52
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White light continuum in negative hollow-core fiber filled with inert gases
摘要： As of the writing of this work, generation of white light continuum (WLC) in hollow-core photonic crystal ˉbers (HCPCF) ˉlled with gases is being thoroughly researched. These structures allow the possibility of adjusting light generation properties by changing the ˉll gas pressure. Kagom(cid:1)e hollow-core PCF and silica capillaries have been used to study the nonlinear e?ects in gases as they facilitate exploring these weak properties. In this paper, we numerically analyze the generation of WLC in a new type of hollow-core PCF, called negative curvature hollow-core ˉber (NCHCF), itself ˉlled with di?erent inert gases. We show that this type of ˉber is a better alternative to the Kagom(cid:1)e and capillary ˉbers because it exhibits low losses and the WLC spectrum generated presents a relatively °at wavelength span from around 400 nm to 2400 nm under certain circumstances.
关键词： inert gases,white light continuum,Nonlinear optics
更新于2025-09-16 10:30:52