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Non-toxic Bi halides have great potential in the field of CO2 photoreduction, but strong charge localization limits their charge separation and transfer. In this study, a series of Cs3BiSbX9 (X = Cl, Br, I) perovskite quantum dots (PQDs) are synthesized by antisolvent recrystallization at room temperature, in which Cs3BiSbBr9 PQDs has high selectivity (94.51%) and yield (15.32 µmol g-1 h-1) of CO2 to CO. In situ DRIFTS and theoretical calculations suggest that the surface charge can be tailored by halogen modulation, allowing for the customization of intermediate species. The BiâBrâSb symmetric charge distribution induced by the halogen Br promotes the formation of bâHCOO and reduces the reaction energy barrier of the rate-limiting step, while the weak electronegativity of Cl and the high electronegativity of I leads to mâHCOO and âCOOH production, which are detrimental to CO generation. This work provides new insights into the design of halide alloy perovskites for CO2 photoreduction.
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We report a gallium phosphide-on-insulator (GaP-OI) photonic platform fabricated by an intermediate-layer bonding process aiming to increase the manufacture scalability in a low-cost manner. This is enabled by the "etch-n-transfer" sequence, which results in inverted rib waveguide structures. The shallow-etched 1.8â µm-wide waveguide has a propagation loss of 23.5â dB/cm at 1550â nm wavelength. Supercontinuum generation based on the self-phase modulation effect is observed when the waveguides are pumped by femtosecond pulses. The nonlinear refractive index of GaP, n2, is extracted to be 1.9 × 10-17â m2/W, demonstrating the great promise of the GaP-OI platform in third-order nonlinear applications.
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Óptica e Fotônica , Refratometria , Desenho de Equipamento , CostelasRESUMO
Due to the tremendous expectations placed on batteries to produce a reliable and secure product, fault detection has become a critical part of the manufacturing process. Manually, it takes much labor and effort to test each battery individually for manufacturing faults including burning, welding that is too high, missing welds, shifting, welding holes, and so forth. Additionally, manual battery fault detection takes too much time and is extremely expensive. We solved this issue by using image processing and machine learning techniques to automatically detect faults in the battery manufacturing process. Our approach will reduce the need for human intervention, save time, and be easy to implement. A CMOS camera was used to collect a large number of images belonging to eight common battery manufacturing faults. The welding area of the batteries' positive and negative terminals was captured from different distances, between 40 and 50 cm. Before deploying the learning models, first, we used the CNN for feature extraction from the image data. To over-sample the dataset, we used the Synthetic Minority Over-sampling Technique (SMOTE) since the dataset was highly imbalanced, resulting in over-fitting of the learning model. Several machine learning and deep learning models were deployed on the CNN-extracted features and over-sampled data. Random forest achieved a significant 84% accuracy with our proposed approach. Additionally, we applied K-fold cross-validation with the proposed approach to validate the significance of the approach, and the logistic regression achieved an 81.897% mean accuracy score and a +/- 0.0255 standard deviation.
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All-optical wavelength conversion technology based on four-wave mixing (FWM) effect is a promising development need of the modern high-speed optical signal processing system. In this work, we report on the polarization insensitive four-wave mixing based on graphene for all optical wavelength conversion. To overcome the polarization sensitivity of FWM, a dual-pump configuration was proposed based on the combination of graphene and the optical fibers. Our experimental results illustrate that by using the dual pump configuration, the FWM-based wavelength conversion efficiency, can be enhanced by graphene with about 8 dB when the state of polarization of the two pumps are parallel. This proposed all-optical wavelength converter based on graphene may provide a new approach for the next generation optical communications and signal processing.
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Here we propose a polarization-dependent gradient phase modulation strategy and fabricate a local polarization-matched metasurface to add/drop polarization multiplexed cylindrical vector beams (CVBs). The two orthogonal linear polarization states in CVB multiplexing will represent as radial- and azimuthal-polarized CVBs, which means that we must introduce independent wave vectors to them for adding/dropping the polarization channels. By designing the rotation angle and geometric sizes of a meta-atom, a local polarization-matched propagation phase plasmonic metasurface is constructed, and the polarization-dependent gradient phases were loaded to perform this operation. As a proof of concept, the polarization multiplexed CVBs, carrying 150-Gbit/s quadrature phase shift keying signals, are successfully added and dropped, and the bit error rates approach 1 × 10-6. In addition to representing a route for adding/dropping polarization multiplexed CVBs, other functional phase modulation of arbitrary orthogonal linear polarization bases is expected, which might find potential applications in polarization encryption imaging, spatial polarization shaping, etc.
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Dioxins in the sintering flue gas are usually removed through integrated elimination technologies by carbonaceous catalysts. However, the regeneration of the used catalyst is poorly investigated, leading to the risk of leakage of dioxins. Herein, the influences of cyclic regenerations on the dioxin removal performance of a catalyst (V2O5/AC) were investigated systematically with dibenzofuran (DBF) as a model pollutant. It was demonstrated that the adsorption capacity and oxidation activity of catalysts significantly declined after several regeneration cycles due to the decreasing external specific surface area and V5+, respectively. Compared with 79.12% DBF directly emitted from a regenerator during N2 regeneration, the emission of DBF was only 29.93% with the modification of the regeneration process through O2 addition and temperature adjustment. The possible regenerated products were also analyzed to disclose the transformation behaviors of DBF. The regeneration mechanisms of DBF followed the transformation pathway of dibenzofuranol, benzofuran, anhydride species, and ultimately to CO2 and H2O. Moreover, the accumulated heavy aromatics on the surface could be decomposed by introducing O2. This research provides a comprehensive understanding of dioxin transformation behavior and a theoretical basis for efficient control of dioxin removal in the whole integrated removal technologies.
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Dioxinas , Dibenzodioxinas Policloradas , Adsorção , Catálise , TemperaturaRESUMO
Sapphire fiber Bragg gratings (SFBGs) inscribed by using femtosecond laser point-by-point (PbP) technology typically have an extremely low reflectivity due to the limited cross-sectional area of refractive index modulations (RIMs) created in sapphire fiber. Hence, we propose and experimentally demonstrate a filamentation process for fabricating PbP SFBGs. This approach provides an efficient method for producing SFBGs at various Bragg wavelengths with a higher reflectivity, since the filament tracks could enlarge the cross-sectional area of RIMs. The influences of the pulse energy and the focal depth on the generation and morphology of the filament tracks were studied, and after optimizing these parameters, high-quality filament tracks with a length of 90 µm and a width of 1.4 µm were produced into sapphire fiber with a diameter of 100 µm. These filament tracks were precisely assembled in sapphire fiber, generating an SFBG with a reflectivity of 2.3%. The total fabrication time for this SFBG only requires ${\sim}{1.1}\;{\rm s}$. Subsequently, a wavelength-division-multiplexed (WDM) SFBG array consisting of five SFBGs was efficiently constructed. Moreover, the high-temperature response of the SFBG array was investigated and the experimental results showed that the SFBG array can withstand a high temperature of 1600°C. Such a WDM SFBG array could serve as quasi-distributed high-temperature sensor which will be promising in many areas, i.e., metallurgical, chemical, and aviation industries.
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Primary open-angle glaucoma (POAG) is the second leading cause of irreversible blindness worldwide. Increased endothelin-1 (ET-1) has been observed in aqueous humour (AH) of POAG patients, resulting in an increase in the out-flow resistance of the AH. However, the underlining mechanisms remain elusive. Using established in vivo and in vitro POAG models, we demonstrated that water channel Aquaporin 1 (AQP1) is down-regulated in trabecular meshwork (TM) cells upon ET-1 exposure, which causes a series of glaucomatous changes, including actin fibre reorganization, collagen production, extracellular matrix deposition and contractility alteration of TM cells. Ectopic expression of AQP1 can reverse ET-1-induced TM tissue remodelling, which requires the presence of ß-catenin. More importantly, we found that ET-1-induced AQP1 suppression is mediated by ATF4, a transcription factor of the unfolded protein response, which binds to the promoter of AQP1 and negatively regulates AQP1 transcription. Thus, we discovered a novel function of ATF4 in controlling the process of TM remodelling in ET-1-induced POAG through transcription suppression of AQP1. Our findings also detail a novel pathological mechanism and a potential therapeutic target for POAG.
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Fator 4 Ativador da Transcrição/metabolismo , Aquaporina 1/metabolismo , Endotelinas/metabolismo , Glaucoma de Ângulo Aberto/patologia , Malha Trabecular/metabolismo , Animais , Humor Aquoso/química , Cegueira/patologia , Linhagem Celular , Modelos Animais de Doenças , Regulação para Baixo , Regulação da Expressão Gênica/genética , Humanos , Coelhos , Transcrição Gênica/genéticaRESUMO
A non-diaphragm fiber gas pressure sensor based on a multimode interferometer (MI) using a hollow-core tube lattice fiber (HC-TLF) as a gas cell is proposed and experimentally demonstrated. The sensor is fabricated by fusion splicing a sandwich structure of a graded-index multimode fiber, HC-TLF, and lead-in/out single mode fiber. Several side-holes are drilled by using a femtosecond laser on the side wall of the HC-TLF to allow gas in and out of the fiber. The positions of side-hole in HC-TLF have been investigated during the experiments, which indicate that the highest gas pressure sensitivity existed as the side-hole located in the gap between adjacent cladding holes of the HC-TLF. The proposed structure exhibits a high sensitivity of 8.1 nm/MPa with the average gas fill time of 2.2 s. This sensor also has low temperature sensitivity and low temperature cross sensitivity of 12.3 pm/°C and 1.5 kPa/°C as the temperature rises to 400°C. In addition, the advantages of the gas pressure sensor, such as small size, rapid response, low temperature cross sensitivity, and simple fabrication process, make it suitable for high-pressure measurement in harsh conditions, e.g., downhole and ocean bottom.
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Taxane-based chemotherapy-loaded drug delivery systems have great potential for cancer treatment. The docetaxel (DTX)-loaded PAMAM-based poly (γ-benzyl-l-glutamate)-b-d-α-tocopheryl polyethylene glycol 1000 succinate (PAM-PBLG-b-TPGS) nanoparticles and the docetaxel (DTX)-loaded PAMAM-based poly (γ-benzyl-l-glutamate) (PAM-PBLG) nanoparticles were designed using a modified nanoprecipitation method. The particle size, encapsulation efficiency (EE), and in vitro release characteristics of the nanoparticles were tested. The effects of the two nanoparticles on the cellular uptake and cell viability on human cervical cancer cell line Hela and the human breast cancer cell line MCF-7 were compared. Furthermore, their antitumor efficiency was evaluated through in vivo tumour growth experiment in comparison with free DTX. PAM-PBLG-b-TPGS nanoparticles displayed high EE, smaller diameter, and a nice releasing profile. Besides, based on the high EE and 'self-controlled' drug release of the DTX-loaded PAM-PBLG-b-TPGS nanoparticles, they exhibited stronger cytotoxicity (lower survival rate) and higher uptake rate than DTX-loaded PAM-PBLG nanoparticles in Hela cells and MCF-7 cells. Furthermore, compared with DTX-loaded PAM-PBLG nanoparticles and free DTX, DTX-loaded PAM-PBLG-b-TPGS nanoparticles produced a potent anti-tumour effect. Thus, the DTX-loaded PAM-PBLG-b-TPGS nanoparticles provide a novel attractive nanocarrier for the DTX delivery of chemotherapy to human breast cancer cells and human cervical cancer cells.
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Antineoplásicos/administração & dosagem , Neoplasias da Mama/tratamento farmacológico , Docetaxel/administração & dosagem , Portadores de Fármacos/química , Neoplasias do Colo do Útero/tratamento farmacológico , Vitamina E/química , Animais , Antineoplásicos/farmacologia , Antineoplásicos/uso terapêutico , Neoplasias da Mama/patologia , Dendrímeros/química , Docetaxel/farmacologia , Docetaxel/uso terapêutico , Liberação Controlada de Fármacos , Feminino , Células HeLa , Humanos , Células MCF-7 , Camundongos Endogâmicos BALB C , Camundongos Nus , Neoplasias do Colo do Útero/patologiaRESUMO
Corn stalk lodging is caused by different factors, including severe wind storms, stalk cannibalization, and stalk rots, and it leads to yield loss. Determining how to rapidly evaluate corn lodging resistance will assist scientists in the field of crop breeding to understand the contributing factors in managing the moisture, chemical fertilizer, and weather conditions for corn growing. This study proposes a non-destructive and direction-insensitive method, using a strain sensor and two single axis angle sensors to measure the corn stalk lodging resistance in the field. An equivalent force whose direction is perpendicular to the stalk is utilized to evaluate the corn lodging properties when a pull force is applied on the corn stalk. A novel measurement device is designed to obtain the equivalent force with the coefficient of variation (CV) of 4.85%. Five corn varieties with two different planting densities are arranged to conduct the experiment using the novel measurement device. The experimental results show that the maximum equivalent force could reach up to 44 N. A strong relationship with the square of the correlation coefficient of 0.88 was obtained between the maximum equivalent forces and the corn field’s stalk lodging rates. Moreover, the stalk lodging angles corresponding to the different pull forces over a measurement time of 20 s shift monotonically along the equivalent forces. Thus, the non-destructive and direction-insensitive method is an excellent tool for rapid analysis of stalk lodging resistance in corn, providing critical information on in-situ lodging dynamics.
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The simultaneous removal of NOx and dioxins has been considered an economical and effective technology of controlling multipollutant flue gas in the context of "carbon peaking and carbon neutrality". However, this technology has not yet been implemented in practical situations, because the interactive relationship between the selective catalytic reduction (SCR) reaction and dioxin catalytic oxidation lacks a deep understanding, especially on a carbon-based catalyst. In this research, the influence of NO and NH3 on the oxidation characteristics and byproducts distribution of dibenzofuran (DBF) was studied on V2O5/AC catalyst. Results indicated that NH3 has a stronger inhibition effect for DBF catalytic oxidation than NO due to obvious competitive adsorption between NH3 and DBF on the V2O5/AC catalyst. In addition, although both NO and NH3 inhibit the complete degradation of DBF, their effects on the byproduct distribution are not consistent. NO primarily affects the level of oxygen-containing byproducts, while NH3 primarily affects the level of alkane byproducts. Furthermore, the SCR reaction activity demonstrated a reduction when DBF was present. The occupation of V2O5 sites by DBF and its oxidizing intermediates has hindered the production of monodentate nitrate and the reactivity of bridged nitrate, resulting in a decrease in SCR activity via the L-H mechanism. This work aims to provide theoretical guidance for simultaneous removal of NOx and dioxins in industrial fumes.
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Dioxins are high chlorine, toxic, and persistent organic pollutants that exert significant pressure on both human and the environment. From the analysis of current pollutant removal of the whole life cycle, such as integrated removal of NOx, SO2 and dioxins in a system, the dioxins oxidation activity as well as the distribution of oxidation products in the presence of SO2 are still a challenge. In this study, dibenzofuran (DBF) was regarded as a model dioxin compound, and V2O5/AC was used as a catalyst to investigate the impact of SO2 on degradation activity and the degradation path of DBF. Various characterization results showed that SO2 could promote the transformation of DBF to intermediates through a reaction with lattice oxygen and lower the apparent activated energy of DBF catalytic oxidation on V2O5/AC catalysts. The density functional theory (DFT) calculations confirmed that SO2 improved the oxidation ability of lattice oxygen on V2O5/AC. The ethyl hydrogen fumarate intermediate decreased and the small-molecule byproducts increased, providing further evidence that SO2 accelerates the degradation of DBF and its intermediates. However, the formation of VOSO4 would inevitably deteriorate the adsorption and oxidation abilities of V2O5/AC. A model is pioneered to describe the relationship between SO2 promotion and VOSO4 inhibition on DBF catalytic oxidation on a V2O5/AC catalyst. This study is expected to provide theoretical guidance for the collaborative abatement of multi-pollutants in flue gas.
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In order to pick up breath signal from correlated noise background of the pulse of heart and artery etc, an algorithm based on wavelet de-noising has been introduced. With wavelet db4, the raw signal was decomposed into the scale space of six layers; threshold treatment was done with the self-adaptive threshold created by Stein's Unbiased Risk Estimate; then the wavelet coefficients were reconstructed. The result showed that the noise was significantly depressed.
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Monitorização Fisiológica/instrumentação , Respiração , Sons Respiratórios , Processamento de Sinais Assistido por Computador , Algoritmos , Artefatos , Oscilação da Parede Torácica/métodos , Humanos , Monitorização Fisiológica/métodos , Análise de OndaletasRESUMO
Surface interface regulation is an important research content in the field of heterogeneous catalysis. To improve the interface interaction between the active component and matrix, tremendous efforts have been dedicated to tailoring the morphology, size, and structure of composite catalysts. In this work, we report a confinement strategy to synthesize a series of core-shell catalysts loaded with metal oxides on titania nanotubes (TNTs), which were applied to the selective catalytic reduction of NOx with ammonia. Interestingly, the core-shell catalyst with confinement of TNTs exhibited the remarkable activity at low temperature region, N2 selectivity and sulfur tolerance. Benefiting from the superior interfacial confinement characteristic of TNTs and Fe2O3, strong component interactions, the surface acid sites and strong oxidizability of MnOx were properly regulated, thus obtained the outstanding activity, N2 selectivity and provide chemical protection to effectively prevent SO2 poisoning. As far as the reaction mechanism, we found that the adsorption and reactivity of Lewis acid sites were the dominant factors affecting the activity in the NH3-SCR process by in situ DRIFT spectra. In general, our work provides an innovative strategy for constructing an TNTs-enwrapped nanocomposite with nano-confinement and core-shell structure to improve the low temperature SCR process.
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Mainly exposed crystal facets and controllable morphology play a key role in the final performance of the preparation of specific nanomaterials. In the present study, a metal-organic framework pyrolysis method without adding solvent modifiers was developed. By adding CO in the calcination atmosphere to change atmosphere ratio, Fe3O4 nanostructures are exposed with different crystal planes and evaluated their performance in NH3-SCR reaction. This study proves that SCR catalytic activity of Fe3O4 nanocrystals is dependent on morphology and crystal facet. Compared with materials exposed (100), catalysts with more (111) show stronger deNOx performance. The preferential exposure of Fe3O4 (111) crystal facets increases the concentration of adsorbed oxygen on the catalyst, showing higher surface acidity, and enhances the interaction among NO, O2 and catalyst, which is conducive to SCR reaction. This is supported by DFT calculations. The results present a great application prospect in preparing nanomaterials with specific crystal structures to effectively treat pollutants.
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Ternary composite with great modulation of electron transfers has attracted a lot of attention from the field of high-performance room-temperature (RT) gas sensing. Herein, walnut-like WO3-Ni-graphene ternary composites were successfully synthesized by the hydrothermal method for formaldehyde (HCHO) sensing at RT. The structural and morphological analyses were carried out by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). SEM and TEM studies confirmed that walnut-like WO3 nanostructures with an average size of 53 ± 23 nm were functionalized. The Raman and XPS results revealed that, due to the deformation of the O-W-O lattice, surface oxygen vacancies Ov and surface-adsorbed oxygen species Oc were present. The gas-sensing measurement shows that the response of the WO3-Ni-Gr composite (86.8%) was higher than that of the Ni-Gr composite (22.7%) for 500 ppm HCHO at RT. Gas-sensing enhancement can be attributed to a p-n heterojunction formation between WO3 and Ni-Gr, Oc, spill-over effect of Ni decoration, and a special walnut-like structure. Moreover, long term stability (%R = 61.41 ± 1.66) for 30 days and high selectivity in the presence of other gases against HCHO suggested that the proposed sensor could be an ideal candidate for future commercial HCHO-sensing in a real environment.
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As a member of the transition metal nitride material family, titanium nitride (TiN) quantum dots (QDs) have attracted great attention in optical and electronic fields because of their excellent optoelectronic properties and favorable stability. Herein, TiN QDs were synthesized and served as a saturable absorber (SA) for an ultrafast fiber laser. Due to the strong nonlinear optical absorption characteristics with a modulation depth of ~33%, the typical fundamental mode-locked pulses and harmonics mode-locked pulses can be easily obtained in an ultrafast erbium-doped fiber laser with a TiN-QD SA. In addition, at the maximum pump power, harmonic mode-locked pulses with a repetition rate of ~1 GHz (164th order) and a pulse duration of ~1.45 ps are achieved. As far as we know, the repetition rate is the highest in the ultrafast fiber laser using TiN QDs as an SA. Thus, these experimental results indicate that TiN QDs can be considered a promising material, showing more potential in the category of ultrafast laser and nonlinear optics.
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As formaldehyde is an extremely toxic volatile organic pollutant, a highly sensitive and selective gas sensor for low-concentration formaldehyde monitoring is of great importance. Herein, metal-organic framework (MOF) derived Pd/PdO@ZnO porous nanostructures were synthesized through hydrothermal method followed by calcination processes. Specifically, porous Pd/PdO@ZnO nanomaterials with large surfaces were synthesized using MOFs as sacrificial templates. During the calcination procedure, an optimized temperature of 500°C was used to form a stable structure. More importantly, intensive PdO@ZnO inside the material and composite interface provides lots of p-n heterojunction to efficiently manipulate room temperature sensing performance. As the height of the energy barrier at the junction of PdO@ZnO exponentially influences the sensor resistance, the Pd/PdO@ZnO nanomaterials exhibit high sensitivity (38.57% for 100 ppm) at room temperature for 1-ppm formaldehyde with satisfactory selectivity towards (ammonia, acetone, methanol, and IPA). Besides, due to the catalytic effect of Pd and PdO, the adsorption and desorption of the gas molecules are accelerated, and the response and recovery time is as small as 256 and 264 s, respectively. Therefore, this MOF-driven strategy can prepare metal oxide composites with high surface area, well-defined morphology, and satisfactory room-temperature formaldehyde gas sensing performance for indoor air quality control.
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Research on light modulation has typically examined the wavelength, intensity, and exposure time of light, and measured rhythm, sleep, and cognitive ability to evaluate the regulatory effects of light variables on physiological and cognitive functions. Although the frequency of light is one of the main dimensions of light, few studies have attempted to manipulate it to test the effect on brain activation and performance. Recently, 40-Hz light stimulation has been proven to significantly alleviate deficits in gamma oscillation of the hippocampus caused by Alzheimer's disease. Although this oscillation is one of the key functional characteristics of performing memory tasks in healthy people, there is no evidence that 40-Hz blue light exposure can effectively regulate brain activities related to complex cognitive tasks. In the current study, we examined the difference in the effects of 40-Hz light or 0-Hz light exposure on brain activation and functional connectivity during a recognition memory task. Through joint augmentation of visual area activation, 40-Hz light enhanced brain areas mostly in the limbic system that are related to memory, such as the hippocampus and thalamus. Conversely, 0-Hz light enhanced brain areas mostly in the prefrontal cortex. Additionally, functional connection analysis, with the hippocampus as the seed point, showed that 40-Hz light enhanced connection with the superior parietal lobe and reduced the connection with the default network. These results indicate that light at a frequency of 40 Hz can change the activity and functional connection of memory-related core brain areas. They also indicate that in the use of light to regulate cognitive functions, its frequency characteristics merit attention.