AIM To evaluate the differences in acute kidney injury(AKI) between acute-on-chronic liver failure(ACLF) and decompensated cirrhosis(DC) patients. METHODS During the period from December 2015 to July 2017, 280 patient...AIM To evaluate the differences in acute kidney injury(AKI) between acute-on-chronic liver failure(ACLF) and decompensated cirrhosis(DC) patients. METHODS During the period from December 2015 to July 2017, 280 patients with hepatitis B virus(HBV)-related ACLF(HBV-ACLF) and 132 patients with HBV-related DC(HBV-DC) who were admitted to our center were recruited consecutively into an observational study. Urine specimens were collected from all subjects and the levels of five urinary tubular injury biomarkers were detected,including neutrophil gelatinase-associated lipocalin(NGAL), interleukin-18(IL-18), liver-type fatty acid binding protein(L-FABP), cystatin C(CysC), and kidney injury molecule-1(KIM-1). Simultaneously, the patient demographics, occurrence and progression of AKI, and response to terlipressin therapy were recorded. All patients were followed up for 3 mo or until death after enrollment. RESULTS AKI occurred in 71 and 28 of HBV-ACLF and HBV-DC patients, respectively(25.4% vs 21.2%, P = 0.358). Among all patients, the levels of four urinary biomarkers(NGAL, CysC, L-FABP, IL-18) were significantly elevated in patients with HBV-ACLF and AKI(ACLF-AKI), compared with that in patients with HBV-DC and AKI(DC-AKI) or those without AKI. There was a higher proportion of patients with AKI progression in ACLF-AKI patients than in DC-AKI patients(49.3% vs 17.9%, P = 0.013). Fortythree patients with ACLF-AKI and 19 patients with DC-AKI were treated with terlipressin. The response rate of ACLFAKI patients was significantly lower than that of patients with DC-AKI(32.6% vs 57.9%, P = 0.018). Furthermore, patients with ACLF-AKI had the lowest 90 d survival rates among all groups(P < 0.001).CONCLUSION AKI in ACLF patients is more likely associated with structural kidney injury, and is more progressive, with a poorer response to terlipressin treatment and a worse prognosis than that in DC patients.展开更多
Carbon-based anode materials are widely used in various battery energy storage systems due to their low cost,wide source,high conductivity and easy morphology control.However,current commercially available anode mater...Carbon-based anode materials are widely used in various battery energy storage systems due to their low cost,wide source,high conductivity and easy morphology control.However,current commercially available anode materials as active materials for lithium-/sodium-ion batteries generally suffer from large volume changes and poor rate performance.In response,we synthesized defect-rich N,S co-doped two dimensional(2D)nanosheet-assembled porous carbon microspheres(N,S-PCS)via simple hydrothermal,carbonization and etching process based on the principle of Schiff base reaction.The N,S-PCS structure is thus constructed by removing Fe7S8 nanoparticles from the carbon skeleton to form porous microspheres with N,S doping.Therefore,the micromorphology characteristic,pore structure and electroconductivity of carbon materials are effectively optimized via heteroatom doping and surface engineering.As expected,the prepared N,S-PCS electrodes exhibit excellent electrochemical performance in both lithium-ion and sodium-ion batteries.For lithium-ion batteries,it achieves reversible capacities of 1045 and 237 mAh g^(-1) at 0.1 and 20 A g^(-1),respectively.For sodium-ion batteries,it shows good cycling stability with a capacity of 157 mAh g^(-1) after 500 cycles at 1 A g^(-1).Experimental and theoretical calculation results confirm that the N,S co-doping strategies help to improve the structural stability,shorten the ion diffusion paths,and promote the reaction kinetics,thus achieving excellent electrochemical performance.This work is instructive for the practical application of nonmetal doping functionalized porous carbon structures for metal-ion batteries.展开更多
A visual and tactile multisensory integrated system is essential for human walking due to the demand for real-time interactions between perception and action.Here,a piezoresistor and MoS_(2)field effect transistor are...A visual and tactile multisensory integrated system is essential for human walking due to the demand for real-time interactions between perception and action.Here,a piezoresistor and MoS_(2)field effect transistor are combined to construct an artificial integration nervous system to simulate perception and synaptic plasticity.The key characteristics of synaptic plasticity are successfully demonstrated by individual pressure signals,individual optical signals,the synergy of optical and pressure signals,which are based on the electron trapping–detrapping mechanism at the MoS_(2)/SiO_(2)interface.We demonstrate that perception under synergy is stronger than perception under optical or pressure signal alone,which is similar to a biological system.Moreover,various distinguishable motion scenarios(combination of the following conditions:external lighting environment of day or night,flat or rough road,movement state of walking or running)are simulated and verified by adjusting the amplitude and frequency of the optical and pressure signals.展开更多
The contradiction between the high number of visually handicapped people and the scarcity of guide dogs has stimulated the demand for electronic guide dogs(EGDs).Here,we demonstrate an EGD by leveraging piezoresistors...The contradiction between the high number of visually handicapped people and the scarcity of guide dogs has stimulated the demand for electronic guide dogs(EGDs).Here,we demonstrate an EGD by leveraging piezoresistors on a MoS_(2)/Ge heterostructure for simultaneous pressure-sensing and optical-sensing functions.The device has excellent gating capability and exhibits large positive and negative photoresponses under visible(532 nm,182 A/W)and infrared(1550 nm,37 A/W)illumination.These characteristics allow the device to efficiently classify different obstacles at all times of day using pressure and light signals.The device reaches nearly 100%accuracy after 48 training sessions when used to classify frequent scenes.The device adopts passive and active detection modes during the day and night,respectively,which improves the battery life of the EGD.This work provides a significant reference for the future design of EGDs,which may help a greater number of visually impaired people by reducing the cost of such devices.展开更多
An intricate relationship exists and interactions occur between gut microbiota and colorectal cancer(CRC).Radical surgery combined with adjuvant chemotherapy(AC) serves as the mainstream therapeutic scheme for most CR...An intricate relationship exists and interactions occur between gut microbiota and colorectal cancer(CRC).Radical surgery combined with adjuvant chemotherapy(AC) serves as the mainstream therapeutic scheme for most CRC patients.The current research was conducted to assess the effect of surgery or chemotherapy on gut microbiota.Forty-three CRC patients who received radical surgery and AC were enrolled.Fecal samples were collected preoperatively,postoperatively,and after the first to fifth cycles of postoperative chemotherapy.The microbial community of each sample was analyzed using high throughput 16S rRNA amplicon sequencing.Compared with preoperative samples,fecal samples collected postoperatively exhibited a significant decrease of obligate anaerobes,tumor-related bacteria,and butyric acid-producing bacteria.However,a significant increase of some conditional pathogens was observed.In addition,the AC regimen(CapeOx) was found to alter intestinal microbiota dramatically.In particular,several changes were observed after chemotherapy including an increase of pathogenic bacteria,the "rebound effect" of chemotherapy-adapted bacteria,the shift of lactate-utilizing microbiota from Veillonella to Butyricimonas and Butyricicoccus,as well as the decrease of probiotics.Both radical surgery and CapeOx chemotherapy exert a non-negligible effect on the gut microbiota of CRC patients.Microbiota-based intervention may be beneficial for patients during postoperative clinical management.展开更多
Active control of metamaterial properties with high tunability of both resonant intensity and frequency is essential for advanced terahertz(THz) applications, ranging from spectroscopy and sensing to communications.Am...Active control of metamaterial properties with high tunability of both resonant intensity and frequency is essential for advanced terahertz(THz) applications, ranging from spectroscopy and sensing to communications.Among varied metamaterials, plasmon-induced transparency(PIT) has enabled active control with giant sensitivity by embedding semiconducting materials. However, there is still a stringent challenge to achieve dynamic responses in both intensity and frequency modulation. Here, an anisotropic THz active metamaterial device with an ultrasensitive modulation feature is proposed and experimentally studied. A radiative-radiative-coupled PIT system is established, with a frequency shift of 0.26 THz in its sharp transparent windows by polarization rotation. Enabled by high charge-carrier mobility and longer diffusion lengths, we utilize a straightforwardly spincoated MAPbI3 film acting as a photoactive medium to endow the device with high sensitivity and ultrafast speed.When the device is pumped by an ultralow laser fluence, the PIT transmission windows at 0.86 and 1.12 THz demonstrate a significant reduction for two polarizations, respectively, with a full recovery time of 561 ps. In addition, we numerically prove the validity that the investigated resonator structure is sensitive to the optically induced conductivity. The hybrid system not only achieves resonant intensity and frequency modulations simultaneously, but also preserves the all-optical-induced switching merits with high sensitivity and speed, which enriches multifunctional subwavelength metamaterial devices at THz frequencies.展开更多
The year 2019 marks the 10th anniversary of the first report of ultrafast fiber laser mode-locked by graphene.This result has had an important impact on ultrafast laser optics and continues to offer new horizons.Herei...The year 2019 marks the 10th anniversary of the first report of ultrafast fiber laser mode-locked by graphene.This result has had an important impact on ultrafast laser optics and continues to offer new horizons.Herein,we mainly review the linear and nonlinear photonic properties of two-dimensional(2D)materials,as well as their nonlinear applications in efficient passive mode-locking devices and ultrafast fiber lasers.Initial works and significant progress in this field,as well as new insights and challenges of 2D materials for ultrafast fiber lasers,are reviewed and analyzed.展开更多
Due to the unique anisotropic chemical and physical properties,two-dimensional(2D)layered materials such as IV-VI monochalcogenides with puckered honeycomb structure,have received considerable interest recently.Among ...Due to the unique anisotropic chemical and physical properties,two-dimensional(2D)layered materials such as IV-VI monochalcogenides with puckered honeycomb structure,have received considerable interest recently.Among the IV-VI layered MX(M=Ge,Sn;X=Se,S)compounds,germanium sulfide(Ge S)stands out for its strongest anisotropic thermal conductivities and figure-of-merit values.Additionally,the layer-independent direct energy bands(Eg^1.6 e V,E1~2.1 e V)of Ge S flake provide excellent insights into further applications as visible photodetectors.Herein,the polarization-tunable nonlinear absorption(NA)patterns of Ge S flake have been systematically investigated.Specifically both the polarization-dependent Raman spectroscopy and the linear absorption(LA)spectroscopy were employed to characterize the lattice orientation and absorption edges of the251-nm Ge S flake.Considering the low damage threshold of Ge S flake,the Ge S/graphene heterostructure was fabricated to increase the threshold without changing the nonlinear properties of Ge S.Our NA results demonstrated that a 600-nm femtosecond laser with different polarizations would excite the saturated-absorption(SA)effect along armchair and reversesaturated-absorption(RSA)effect along zigzag in the Ge S/graphene heterostructure.Moreover,the function of the polarization-based Ge S/graphene heterostructure all-optical switch was experimentally verified.Notably,thanks to the polarization-dependent NA patterns(SA/RSA)of Ge S,the"ON"and"OFF"states of the all-optical switch can be accomplished by high and low transmittance states of continuous-wave laser(532 nm,80 n W),whose state can be controlled by the polarization of femtosecond switching laser(600 nm,35 fs,500 Hz,12 GW cm-2).The ON/OFF ratio can achieve up to 17%by changing polarization,compared with the ratios of 3.0%by increasing the incident power of switching light in our experiment.The polarization-tunable absorption patterns introduced in this work open up real perspectives for the next-generation optoelectronic devices based on Ge S/graphene heterostructure.展开更多
Metamaterials play an important role in the modulation of amplitude and group delay in the terahertz(THz)regime on account of their optical properties,which are rare in natural materials.Here an ultrafast anisotropic ...Metamaterials play an important role in the modulation of amplitude and group delay in the terahertz(THz)regime on account of their optical properties,which are rare in natural materials.Here an ultrafast anisotropic switch of the plasmon-induced transparency(PIT)effect is experimentally and numerically demonstrated by metamaterial devices composed of two pairs of planar split-ring resonators and a pair of closed-ring resonators.By integration with a germanium(Ge)film,a recovery time of 3 ps and a decay constant of 785 fs are realized in the metadevice.Stimulated by the exterior optical pump,the PIT windows at different frequencies are switched off with an excellent property of slow light for vertical and horizontal THz polarizations,realizing an astonishing modulation depth as high as 99.06%.This work provides a new platform for ultrafast anisotropic metadevices tunable for amplitude and group delay.展开更多
We experimentally demonstrate for the first time an active all-optical ultrafast modulation of electromagnetically induced transparency-like effect in a hybrid device of sapphire/Si/metamaterial. From numerical simula...We experimentally demonstrate for the first time an active all-optical ultrafast modulation of electromagnetically induced transparency-like effect in a hybrid device of sapphire/Si/metamaterial. From numerical simulations, it can be deducted that the tuning process is attributed to the coupling between the dark mode existing in split-ring resonators and the bright mode existing in cut wire resonators. The transmission amplitude modulation is accompanied by the slow-light effect. In addition, the ultrafast formation process is measured to be as fast as 2 ps. This work should make an important contribution to novel chip-scale photonic devices and terahertz communications.展开更多
The layered MoS2 has recently attracted significant attention for its excellent nonlinear optical properties.Here,the ultrafast nonlinear optical (NLO)absorption and excited carrier dynamics of layered MoS2(monolayer,...The layered MoS2 has recently attracted significant attention for its excellent nonlinear optical properties.Here,the ultrafast nonlinear optical (NLO)absorption and excited carrier dynamics of layered MoS2(monolayer,3-4 layers,and 6-8 layers)are investigated via Z-scan and transient absorption spectra.Our experimental results reveal that NLO absorption coefficients of these MoS2 increase from-27×10^3cm/GW to -11×10^3cm/GW with more layers at 400-nm laser excitation,while the values decrease from 2.0×10^3cm/GW to 0.8×10^3cm/GW at 800nm.In addition, at high pump fluence,when the NLO response occurs,the results show that not only the reformation of the excitonic bands,but also the recovery time of NLO response decreases from 150ps to lOOps with an increasing number of layers,while the reductive energy of A excitonic band decreases from 191.TmeV to 51.1meV.The intriguing NLO response of MoS2 provides excellent potentials for the next-generation optoelectronic and photonic devices.展开更多
Broadband transient reflectivity traces were measured for Bi_2 Se_3 thin films with various substrates via a 400 nm pump–white-light-probe setup. We have verified the existence of a second Dirac surface state in Bi_2...Broadband transient reflectivity traces were measured for Bi_2 Se_3 thin films with various substrates via a 400 nm pump–white-light-probe setup. We have verified the existence of a second Dirac surface state in Bi_2 Se_3 and qualitatively located it by properly analyzing the traces acquired at different probe wavelengths. Referring to the band structure of Bi_2 Se_3, the relaxation mechanisms for photo-excited electrons with different energies are also revealed and studied. Our results show a second rise of the transient reflection signal at the time scale of several picoseconds. The types of substrate can also significantly affect the dynamics of the rising signal. This phenomenon is attributed to the effect of lattice heating and coherent phonon processes. The mechanism study in this work will benefit the fabrication of high-performance photonic devices based on topological insulators.展开更多
Standing on the potential for high-speed modulation and switching in the terahertz (THz) regime, all-optical approaches whose response speeds mainly depend on the lifetime of nonequilibrium free carriers have attracte...Standing on the potential for high-speed modulation and switching in the terahertz (THz) regime, all-optical approaches whose response speeds mainly depend on the lifetime of nonequilibrium free carriers have attracted a tremendous attention. Here, we establish a novel bi-direction THz modulation experiment controlled by femtosecond laser for new functional devices. Specifically, time-resolved transmission measurements are conducted on a series of thin layers Bi2Se3 films fabricated straightforwardly on AI2O3 substrates, with the pump fluence range from 25(iJ/cm2 to 200 |iJ/cm2 per pulse. After photoexcitation, an ultrafast switching of THz wave with a full recovery time of ?1 Ops is observed. For a longer timescale, a photoinduced increase in the transmitted THz amplitude is found in the 8 and 10 quintuple layers (QL) BizSR, which shows a thickness-dependent topological phase transition. Additionally, the broadband modulation effect of the 8 QL Bi2Se3 film is presented at the time delays of 2.2ps and 12.5ps which have a maximum modulation depth of 6.4% and 1.3% under the pump fluence of 200(iJ/cm2, respectively. Furthermore, the absorption of a optical phonon at 1.9 THz shows a time-dependent evolution which is consistent with the cooling of lattice temperature.展开更多
A series of symmetrical peptidomimetics (3-8) based on cysteine-modified cyclo(L-Lys-L-Lys)s were synthesized, and their gelation capability in organic solvents was dominated by fluorenylmethyloxycarbonyl (Fmoc)...A series of symmetrical peptidomimetics (3-8) based on cysteine-modified cyclo(L-Lys-L-Lys)s were synthesized, and their gelation capability in organic solvents was dominated by fluorenylmethyloxycarbonyl (Fmoc) and triphenylmethyl (Trt) protecting groups and the exchange of thiol-to-disulfide as well. The peptidomimetics holding Trt (3 and 4) showed no gel performance, while the Fmoc groups promoted 5 and 6 to give rise to thermo-reversible organogels in a number of organic solvents. The self-assembled fibrillar networks were distinctly evidenced in the organogels by transmission electron micros- copy (TEM) and scanning electron microscopy (SEM) observations. Fourier transform infrared spectroscopy (FT-IR) and fluorescence analyses revealed that the hydrogen bonding and ^-rt stacking play as major driving forces for the self-assembly of these organogelators. A 13-turn secondary structure was deduced for the organogel of 6 by virtue of X-ray diffraction, FT-IR and circular dichroism (CD) measurements, and an interdigitated bilayer structure was also presented.展开更多
We present a theoretical analysis of a novel multi-channel light amplification photonic system on chip,where the nonlinear Raman amplification phenomenon in the silicon(Si)wire waveguide is considered.Particularly,a c...We present a theoretical analysis of a novel multi-channel light amplification photonic system on chip,where the nonlinear Raman amplification phenomenon in the silicon(Si)wire waveguide is considered.Particularly,a compact and temperature insensitive Mach–Zehnder interferometer filter working as demultiplexer is also exploited,allowing for the whole Si photonic system to be free from thermal interference.The propagation of the multi-channel pump and Stokes lights is described by a rigorous theoretical model that incorporates all relevant linear and nonlinear optical effects,including the intrinsic waveguide optical losses,first-and second-order frequency dispersion,self-phase and cross-phase modulation,phase shift and two-photon absorption,free-carriers dynamics,as well as the inter-pulse Raman interaction.Notably,to prevent excessive drift of the transmission window of the demultiplexer caused by ambient temperature variations and high thermo-optical coefficient of Si,an asymmetric waveguide width is adopted in the upper and lower arms of each Mach–Zehnder interferometer lattice cell.A Chebyshev half-band filter is utilized to achieve a flat pass-band transmission,achieving a temperature sensitivity of<1.4 pm=K and over 100 K temperature span.This all-Si amplifier shows a thermally robust behavior,which is desired by future Si-on-insulator(SOI)applications.展开更多
基金Supported by the Innovation Team Development Plan of the Ministry of Education,No.IRT_14R20National Natural Science foundation of China,No.81571989
文摘AIM To evaluate the differences in acute kidney injury(AKI) between acute-on-chronic liver failure(ACLF) and decompensated cirrhosis(DC) patients. METHODS During the period from December 2015 to July 2017, 280 patients with hepatitis B virus(HBV)-related ACLF(HBV-ACLF) and 132 patients with HBV-related DC(HBV-DC) who were admitted to our center were recruited consecutively into an observational study. Urine specimens were collected from all subjects and the levels of five urinary tubular injury biomarkers were detected,including neutrophil gelatinase-associated lipocalin(NGAL), interleukin-18(IL-18), liver-type fatty acid binding protein(L-FABP), cystatin C(CysC), and kidney injury molecule-1(KIM-1). Simultaneously, the patient demographics, occurrence and progression of AKI, and response to terlipressin therapy were recorded. All patients were followed up for 3 mo or until death after enrollment. RESULTS AKI occurred in 71 and 28 of HBV-ACLF and HBV-DC patients, respectively(25.4% vs 21.2%, P = 0.358). Among all patients, the levels of four urinary biomarkers(NGAL, CysC, L-FABP, IL-18) were significantly elevated in patients with HBV-ACLF and AKI(ACLF-AKI), compared with that in patients with HBV-DC and AKI(DC-AKI) or those without AKI. There was a higher proportion of patients with AKI progression in ACLF-AKI patients than in DC-AKI patients(49.3% vs 17.9%, P = 0.013). Fortythree patients with ACLF-AKI and 19 patients with DC-AKI were treated with terlipressin. The response rate of ACLFAKI patients was significantly lower than that of patients with DC-AKI(32.6% vs 57.9%, P = 0.018). Furthermore, patients with ACLF-AKI had the lowest 90 d survival rates among all groups(P < 0.001).CONCLUSION AKI in ACLF patients is more likely associated with structural kidney injury, and is more progressive, with a poorer response to terlipressin treatment and a worse prognosis than that in DC patients.
基金supported by the National Natural Science Foundation of China(21905152 and 52302273)the Youth Innovation Team Project for Talent Introduction and Cultivation in Universities of Shandong Province+2 种基金the Taishan Scholar Project of Shandong Province of China(tsqn202211160 and tsqn202312199)the China Postdoctoral Science Foundation(2022M713249)the Shandong Provincial Natural Science Foundation of China(ZR2023QE176)。
文摘Carbon-based anode materials are widely used in various battery energy storage systems due to their low cost,wide source,high conductivity and easy morphology control.However,current commercially available anode materials as active materials for lithium-/sodium-ion batteries generally suffer from large volume changes and poor rate performance.In response,we synthesized defect-rich N,S co-doped two dimensional(2D)nanosheet-assembled porous carbon microspheres(N,S-PCS)via simple hydrothermal,carbonization and etching process based on the principle of Schiff base reaction.The N,S-PCS structure is thus constructed by removing Fe7S8 nanoparticles from the carbon skeleton to form porous microspheres with N,S doping.Therefore,the micromorphology characteristic,pore structure and electroconductivity of carbon materials are effectively optimized via heteroatom doping and surface engineering.As expected,the prepared N,S-PCS electrodes exhibit excellent electrochemical performance in both lithium-ion and sodium-ion batteries.For lithium-ion batteries,it achieves reversible capacities of 1045 and 237 mAh g^(-1) at 0.1 and 20 A g^(-1),respectively.For sodium-ion batteries,it shows good cycling stability with a capacity of 157 mAh g^(-1) after 500 cycles at 1 A g^(-1).Experimental and theoretical calculation results confirm that the N,S co-doping strategies help to improve the structural stability,shorten the ion diffusion paths,and promote the reaction kinetics,thus achieving excellent electrochemical performance.This work is instructive for the practical application of nonmetal doping functionalized porous carbon structures for metal-ion batteries.
基金the National Key Research and Development Program of China(No.2019YFB2204400)the Natural Science Basic Research Program of Shaanxi(No.2022JQ-650).
文摘A visual and tactile multisensory integrated system is essential for human walking due to the demand for real-time interactions between perception and action.Here,a piezoresistor and MoS_(2)field effect transistor are combined to construct an artificial integration nervous system to simulate perception and synaptic plasticity.The key characteristics of synaptic plasticity are successfully demonstrated by individual pressure signals,individual optical signals,the synergy of optical and pressure signals,which are based on the electron trapping–detrapping mechanism at the MoS_(2)/SiO_(2)interface.We demonstrate that perception under synergy is stronger than perception under optical or pressure signal alone,which is similar to a biological system.Moreover,various distinguishable motion scenarios(combination of the following conditions:external lighting environment of day or night,flat or rough road,movement state of walking or running)are simulated and verified by adjusting the amplitude and frequency of the optical and pressure signals.
基金supported by the National Natural Science Basic Research Program of Shaanxi(No.2022JQ-650)the Natural Science Foundation of China(NSFC)(No.62204188)the Cooperation Program of XDU-Chongqing IC Innovation Research Institute(No.CQIRI-CXYHT-2022-13)。
文摘The contradiction between the high number of visually handicapped people and the scarcity of guide dogs has stimulated the demand for electronic guide dogs(EGDs).Here,we demonstrate an EGD by leveraging piezoresistors on a MoS_(2)/Ge heterostructure for simultaneous pressure-sensing and optical-sensing functions.The device has excellent gating capability and exhibits large positive and negative photoresponses under visible(532 nm,182 A/W)and infrared(1550 nm,37 A/W)illumination.These characteristics allow the device to efficiently classify different obstacles at all times of day using pressure and light signals.The device reaches nearly 100%accuracy after 48 training sessions when used to classify frequent scenes.The device adopts passive and active detection modes during the day and night,respectively,which improves the battery life of the EGD.This work provides a significant reference for the future design of EGDs,which may help a greater number of visually impaired people by reducing the cost of such devices.
基金supported by the National Natural Science Foundation of China (81230057, 81372615, 81472262 and 81200264)the Emerging Cutting-Edge Technology Joint Research Projects of Shanghai (SHDC12012106)+2 种基金Tongji University Subject Pilot Program (162385)Lijieshou Intestinal Barrier Foundation (LJS-201701)Specialized Research Fund for the Combine Traditional Chinese and Western Medicine in General Hospital of Shanghai (ZHYY-ZXYJHZX-1-201704)
文摘An intricate relationship exists and interactions occur between gut microbiota and colorectal cancer(CRC).Radical surgery combined with adjuvant chemotherapy(AC) serves as the mainstream therapeutic scheme for most CRC patients.The current research was conducted to assess the effect of surgery or chemotherapy on gut microbiota.Forty-three CRC patients who received radical surgery and AC were enrolled.Fecal samples were collected preoperatively,postoperatively,and after the first to fifth cycles of postoperative chemotherapy.The microbial community of each sample was analyzed using high throughput 16S rRNA amplicon sequencing.Compared with preoperative samples,fecal samples collected postoperatively exhibited a significant decrease of obligate anaerobes,tumor-related bacteria,and butyric acid-producing bacteria.However,a significant increase of some conditional pathogens was observed.In addition,the AC regimen(CapeOx) was found to alter intestinal microbiota dramatically.In particular,several changes were observed after chemotherapy including an increase of pathogenic bacteria,the "rebound effect" of chemotherapy-adapted bacteria,the shift of lactate-utilizing microbiota from Veillonella to Butyricimonas and Butyricicoccus,as well as the decrease of probiotics.Both radical surgery and CapeOx chemotherapy exert a non-negligible effect on the gut microbiota of CRC patients.Microbiota-based intervention may be beneficial for patients during postoperative clinical management.
基金National Natural Science Foundation of China(NSFC)(11802339,11804387,11805276,61801498,61805282)Scientific Researches Foundation of National University of Defense Technology(ZK16-03-59,ZK18-01-03,ZK18-03-22,ZK18-03-36)+4 种基金Natural Science Foundation of Hunan Province(2016JJ1021)Open Director Fund of State Key Laboratory of Pulsed Power Laser Technology(SKL2018ZR05)Open Research Fund of Hunan Provincial Key Laboratory of High Energy Technology(GNJGJS03)Opening Foundation of State Key Laboratory of Laser Interaction with Matter(SKLLIM1702)Youth Talent Lifting Project(17-JCJQ-QT-004)
文摘Active control of metamaterial properties with high tunability of both resonant intensity and frequency is essential for advanced terahertz(THz) applications, ranging from spectroscopy and sensing to communications.Among varied metamaterials, plasmon-induced transparency(PIT) has enabled active control with giant sensitivity by embedding semiconducting materials. However, there is still a stringent challenge to achieve dynamic responses in both intensity and frequency modulation. Here, an anisotropic THz active metamaterial device with an ultrasensitive modulation feature is proposed and experimentally studied. A radiative-radiative-coupled PIT system is established, with a frequency shift of 0.26 THz in its sharp transparent windows by polarization rotation. Enabled by high charge-carrier mobility and longer diffusion lengths, we utilize a straightforwardly spincoated MAPbI3 film acting as a photoactive medium to endow the device with high sensitivity and ultrafast speed.When the device is pumped by an ultralow laser fluence, the PIT transmission windows at 0.86 and 1.12 THz demonstrate a significant reduction for two polarizations, respectively, with a full recovery time of 561 ps. In addition, we numerically prove the validity that the investigated resonator structure is sensitive to the optically induced conductivity. The hybrid system not only achieves resonant intensity and frequency modulations simultaneously, but also preserves the all-optical-induced switching merits with high sensitivity and speed, which enriches multifunctional subwavelength metamaterial devices at THz frequencies.
基金National Natural Science Foundation of China(11802339,11804387,11805276,61801498,61805282)China Postdoctoral Innovation Science Foundation(BX20180373)+5 种基金Scientific Researches Foundation of National University of Defense Technology(ZK16-03-59,ZK18-01-03,ZK18-03-22,ZK18-03-36)Natural Science Foundation of Hunan Province(2016JJ1021)Open Director Fund of State Key Laboratory of Pulsed Power Laser Technology(SKL2018ZR05)Open Research Fund of Hunan Provincial Key Laboratory of High Energy Technology(GNJGJS03)Opening Foundation of State Key Laboratory of Laser Interaction with Matter(SKLLIM1702)Youth Talent Lifting Project(17-JCJQ-QT-004)。
文摘The year 2019 marks the 10th anniversary of the first report of ultrafast fiber laser mode-locked by graphene.This result has had an important impact on ultrafast laser optics and continues to offer new horizons.Herein,we mainly review the linear and nonlinear photonic properties of two-dimensional(2D)materials,as well as their nonlinear applications in efficient passive mode-locking devices and ultrafast fiber lasers.Initial works and significant progress in this field,as well as new insights and challenges of 2D materials for ultrafast fiber lasers,are reviewed and analyzed.
基金financial support from the National Natural Science Foundation of China(11802339,11805276,61805282,61801498,11804387,and 11902358)the Scientific Researches Foundation of National University of Defense Technology(ZK16-03-59,ZK18-01-03,ZK18-03-36,and ZK18-03-22)+4 种基金the Natural Science Foundation of Hunan province(2016JJ1021)the Open Director Fund of State Key Laboratory of Pulsed Power Laser Technology(SKL2018ZR05)the Open Research Fund of Hunan Provincial Key Laboratory of High Energy Technology(GNJGJS03)the Opening Foundation of State Key Laboratory of Laser Interaction with Matter(SKLLIM1702)the Youth Talent Lifting Project(17-JCJQ-QT004)。
文摘Due to the unique anisotropic chemical and physical properties,two-dimensional(2D)layered materials such as IV-VI monochalcogenides with puckered honeycomb structure,have received considerable interest recently.Among the IV-VI layered MX(M=Ge,Sn;X=Se,S)compounds,germanium sulfide(Ge S)stands out for its strongest anisotropic thermal conductivities and figure-of-merit values.Additionally,the layer-independent direct energy bands(Eg^1.6 e V,E1~2.1 e V)of Ge S flake provide excellent insights into further applications as visible photodetectors.Herein,the polarization-tunable nonlinear absorption(NA)patterns of Ge S flake have been systematically investigated.Specifically both the polarization-dependent Raman spectroscopy and the linear absorption(LA)spectroscopy were employed to characterize the lattice orientation and absorption edges of the251-nm Ge S flake.Considering the low damage threshold of Ge S flake,the Ge S/graphene heterostructure was fabricated to increase the threshold without changing the nonlinear properties of Ge S.Our NA results demonstrated that a 600-nm femtosecond laser with different polarizations would excite the saturated-absorption(SA)effect along armchair and reversesaturated-absorption(RSA)effect along zigzag in the Ge S/graphene heterostructure.Moreover,the function of the polarization-based Ge S/graphene heterostructure all-optical switch was experimentally verified.Notably,thanks to the polarization-dependent NA patterns(SA/RSA)of Ge S,the"ON"and"OFF"states of the all-optical switch can be accomplished by high and low transmittance states of continuous-wave laser(532 nm,80 n W),whose state can be controlled by the polarization of femtosecond switching laser(600 nm,35 fs,500 Hz,12 GW cm-2).The ON/OFF ratio can achieve up to 17%by changing polarization,compared with the ratios of 3.0%by increasing the incident power of switching light in our experiment.The polarization-tunable absorption patterns introduced in this work open up real perspectives for the next-generation optoelectronic devices based on Ge S/graphene heterostructure.
基金National Natural Science Foundation of China(11802339,11804387,11805276,11902358,61801498,61805282)Scientific Researches Foundation of National University of Defense Technology(ZK16-03-59,ZK18-01-0,ZK18-03-22,ZK18-03-36)+5 种基金Natural Science Foundation of Hunan Province(2016JJ1021)Open Director Fund of State Key Laboratory of Pulsed Power Laser Technology(SKL2018ZR05)Open Research Fund of Hunan Provincial Key Laboratory of High Energy Technology(GNJGJS03)Opening Foundation of State Key Laboratory of Laser Interaction with Matter(SKLLIM1702)Youth Talent Lifting Project(17-JCJQ-QT-004)The authors are grateful to Prof.LeiShi from Fudan University for providing the FDTD software.
文摘Metamaterials play an important role in the modulation of amplitude and group delay in the terahertz(THz)regime on account of their optical properties,which are rare in natural materials.Here an ultrafast anisotropic switch of the plasmon-induced transparency(PIT)effect is experimentally and numerically demonstrated by metamaterial devices composed of two pairs of planar split-ring resonators and a pair of closed-ring resonators.By integration with a germanium(Ge)film,a recovery time of 3 ps and a decay constant of 785 fs are realized in the metadevice.Stimulated by the exterior optical pump,the PIT windows at different frequencies are switched off with an excellent property of slow light for vertical and horizontal THz polarizations,realizing an astonishing modulation depth as high as 99.06%.This work provides a new platform for ultrafast anisotropic metadevices tunable for amplitude and group delay.
基金supported by the National Natural Science Foundation of China (NSFC)(Nos. 11802339,11805276,61805282,61801498,11804387,and 11902358)the Scientific Researches Foundation of National University of Defense Technology (Nos. ZK16-03-59,ZK18-01-03,ZK18-03-36,ZK18-03-22)+5 种基金the Natural Science Foundation of Hunan Province (No. 2016JJ1021)the Hunan Provincial Innovation Foundation for Postgraduate (No. CX2018B006)the Open Director Fund of State Key Laboratory of Pulsed Power Laser Technology (No. SKL2018ZR05)the Open Research Fund of Hunan Provincial Key Laboratory of High Energy Technology (No. GNJGJS03)the Open Foundation of State Key Laboratory of Laser Interaction with Matter(No. SKLLIM1702)the Youth Talent Lifting Project(No. 17-JCJQ-QT-004)。
文摘We experimentally demonstrate for the first time an active all-optical ultrafast modulation of electromagnetically induced transparency-like effect in a hybrid device of sapphire/Si/metamaterial. From numerical simulations, it can be deducted that the tuning process is attributed to the coupling between the dark mode existing in split-ring resonators and the bright mode existing in cut wire resonators. The transmission amplitude modulation is accompanied by the slow-light effect. In addition, the ultrafast formation process is measured to be as fast as 2 ps. This work should make an important contribution to novel chip-scale photonic devices and terahertz communications.
文摘The layered MoS2 has recently attracted significant attention for its excellent nonlinear optical properties.Here,the ultrafast nonlinear optical (NLO)absorption and excited carrier dynamics of layered MoS2(monolayer,3-4 layers,and 6-8 layers)are investigated via Z-scan and transient absorption spectra.Our experimental results reveal that NLO absorption coefficients of these MoS2 increase from-27×10^3cm/GW to -11×10^3cm/GW with more layers at 400-nm laser excitation,while the values decrease from 2.0×10^3cm/GW to 0.8×10^3cm/GW at 800nm.In addition, at high pump fluence,when the NLO response occurs,the results show that not only the reformation of the excitonic bands,but also the recovery time of NLO response decreases from 150ps to lOOps with an increasing number of layers,while the reductive energy of A excitonic band decreases from 191.TmeV to 51.1meV.The intriguing NLO response of MoS2 provides excellent potentials for the next-generation optoelectronic and photonic devices.
基金supported by the Opening Foundation of State Key Laboratory of High Performance Computing(Nos.201601-01,201601-02,and 201601-03)the Scientific Researches Foundation of National University of Defense Technology(No.zk16-03-59)+3 种基金the Open Research Fund of State Key Laboratory of Pulsed Power Laser Technology(No.SKL2017KF06)the Director Fund of State Key Laboratory of Pulsed Power Laser Technology(No.SKL2018ZR05)the Funds for International Cooperation and Exchange of National Natural Science Foundation of China(Nos.61120106 and 60921062)the National Natural Science Foundation of China(Nos.11802339 and 11805276)
文摘Broadband transient reflectivity traces were measured for Bi_2 Se_3 thin films with various substrates via a 400 nm pump–white-light-probe setup. We have verified the existence of a second Dirac surface state in Bi_2 Se_3 and qualitatively located it by properly analyzing the traces acquired at different probe wavelengths. Referring to the band structure of Bi_2 Se_3, the relaxation mechanisms for photo-excited electrons with different energies are also revealed and studied. Our results show a second rise of the transient reflection signal at the time scale of several picoseconds. The types of substrate can also significantly affect the dynamics of the rising signal. This phenomenon is attributed to the effect of lattice heating and coherent phonon processes. The mechanism study in this work will benefit the fabrication of high-performance photonic devices based on topological insulators.
文摘Standing on the potential for high-speed modulation and switching in the terahertz (THz) regime, all-optical approaches whose response speeds mainly depend on the lifetime of nonequilibrium free carriers have attracted a tremendous attention. Here, we establish a novel bi-direction THz modulation experiment controlled by femtosecond laser for new functional devices. Specifically, time-resolved transmission measurements are conducted on a series of thin layers Bi2Se3 films fabricated straightforwardly on AI2O3 substrates, with the pump fluence range from 25(iJ/cm2 to 200 |iJ/cm2 per pulse. After photoexcitation, an ultrafast switching of THz wave with a full recovery time of ?1 Ops is observed. For a longer timescale, a photoinduced increase in the transmitted THz amplitude is found in the 8 and 10 quintuple layers (QL) BizSR, which shows a thickness-dependent topological phase transition. Additionally, the broadband modulation effect of the 8 QL Bi2Se3 film is presented at the time delays of 2.2ps and 12.5ps which have a maximum modulation depth of 6.4% and 1.3% under the pump fluence of 200(iJ/cm2, respectively. Furthermore, the absorption of a optical phonon at 1.9 THz shows a time-dependent evolution which is consistent with the cooling of lattice temperature.
基金the National Natural Science Foundation of China (21174018)
文摘A series of symmetrical peptidomimetics (3-8) based on cysteine-modified cyclo(L-Lys-L-Lys)s were synthesized, and their gelation capability in organic solvents was dominated by fluorenylmethyloxycarbonyl (Fmoc) and triphenylmethyl (Trt) protecting groups and the exchange of thiol-to-disulfide as well. The peptidomimetics holding Trt (3 and 4) showed no gel performance, while the Fmoc groups promoted 5 and 6 to give rise to thermo-reversible organogels in a number of organic solvents. The self-assembled fibrillar networks were distinctly evidenced in the organogels by transmission electron micros- copy (TEM) and scanning electron microscopy (SEM) observations. Fourier transform infrared spectroscopy (FT-IR) and fluorescence analyses revealed that the hydrogen bonding and ^-rt stacking play as major driving forces for the self-assembly of these organogelators. A 13-turn secondary structure was deduced for the organogel of 6 by virtue of X-ray diffraction, FT-IR and circular dichroism (CD) measurements, and an interdigitated bilayer structure was also presented.
基金This work was supported by the National Natural Science Foundation of China(No.11902358)the Scientific Researches Foundation of National University of Defense Technology(Nos.ZK18-03-36 and ZK18-01-03).
文摘We present a theoretical analysis of a novel multi-channel light amplification photonic system on chip,where the nonlinear Raman amplification phenomenon in the silicon(Si)wire waveguide is considered.Particularly,a compact and temperature insensitive Mach–Zehnder interferometer filter working as demultiplexer is also exploited,allowing for the whole Si photonic system to be free from thermal interference.The propagation of the multi-channel pump and Stokes lights is described by a rigorous theoretical model that incorporates all relevant linear and nonlinear optical effects,including the intrinsic waveguide optical losses,first-and second-order frequency dispersion,self-phase and cross-phase modulation,phase shift and two-photon absorption,free-carriers dynamics,as well as the inter-pulse Raman interaction.Notably,to prevent excessive drift of the transmission window of the demultiplexer caused by ambient temperature variations and high thermo-optical coefficient of Si,an asymmetric waveguide width is adopted in the upper and lower arms of each Mach–Zehnder interferometer lattice cell.A Chebyshev half-band filter is utilized to achieve a flat pass-band transmission,achieving a temperature sensitivity of<1.4 pm=K and over 100 K temperature span.This all-Si amplifier shows a thermally robust behavior,which is desired by future Si-on-insulator(SOI)applications.