AIM: To study liver cell apoptosis caused by the toxicity of selenium and observe the alteration of choline compounds using in vitro 9.4T high resolution magnetic resonance spectroscopy. METHODS: Twenty male Wistar ra...AIM: To study liver cell apoptosis caused by the toxicity of selenium and observe the alteration of choline compounds using in vitro 9.4T high resolution magnetic resonance spectroscopy. METHODS: Twenty male Wistar rats were randomly divided into two groups. The rats in the treatment group were intraperitoneally injected with sodium selenite and the control group with distilled water. All rats were sacrifi ced and the livers were dissected. 1H-MRS data were collected using in vitro 9.4T high resolution magnetic resonance spectrometer. Spectra were processed using XWINNMR and MestRe-c 4.3. HE and TUNEL staining was employed to detect and confi rm the change of liver cells. RESULTS: Good 1H-MR spectra of perchloric acid extract from liver tissue of rats were obtained. The conventional metabolites were detected and assigned. Concentrations of different ingredient choline compounds in treatment group vs control group were as follows: total choline compounds,5.08 ± 0.97 mmol/L vs 3.81 ± 1.16 mmol/L (P = 0.05); and free choline,1.07 ± 0.23 mmol/L vs 0.65 ± 0.20 mmol/L (P = 0.00). However,there was no statistical signif icance between the two groups. The hepatic sinus and cellular structure of hepatic cells in treatmentgroup were abnormal. Apoptosis of hepatic cells was confi rmed by TUNEL assay. CONCLUSION: High dose selenium compounds can cause the rat liver lesion and induce cell apoptosis in vivo. High resolution 1H-MRS in vitro can detect diversified metabolism. The changing trend for different ingredient of choline compounds is not completely the same at early period of apoptosis.展开更多
AIM: To evaluate the feasibility of quantifying liver choline concentrations in both normal and apoptotic rabbit livers in vivo, using 1H magnetic resonance spectroscopy (1H-MRS). METHODS: 1H-MRS was performed in 18 r...AIM: To evaluate the feasibility of quantifying liver choline concentrations in both normal and apoptotic rabbit livers in vivo, using 1H magnetic resonance spectroscopy (1H-MRS). METHODS: 1H-MRS was performed in 18 rabbits using a 1.5T GE MR system with an eight-channel head/neck receiving coil. Fifteen rabbits were injected with sodium selenite at a dose of 10 μmol/kg to induce the liver cell apoptosis. Point-resolved spectroscopy sequencelocalized spectra were obtained from 10 livers once before and once 24 h after sodium selenite injection in vivo. T1 and T2 relaxation time of water and choline was measured separately in the livers of three healthy rabbits and three selenite-treated rabbits. Hematoxylin and eosin and dUTP-biotin nick end labeling (TUNEL) staining was used to detect and confirm apoptosis. Choline peak areas were measured relative to unsuppressed water using LCModel. Relaxation attenuation was corrected using the average of T1 and T2 relaxation time. The choline concentration was quantified using a formula, which was tested by a phantom with a known concentration. RESULTS: Apoptosis of hepatic cells was confirmed by TUNEL assay. In phantom experiment, the choline concentration (3.01 mmol/L), measured by 1H-MRS, was in good agreement with the actual concentration (3 mmol/L). The average T1 and T2 relaxation time of choline was 612 ± 15 ms and 74 ± 4 ms in the control group and 670 ± 27 ms and 78 ± 5 ms in apoptotic livers in vivo, respectively. Choline was quantified in 10 rabbits, once before and once after the injection with sodium selenite. The choline concentration decreased from 14.5 ± 7.57 mmol/L before sodium selenite injection to 10.8 ± 6.58 mmol/L (mean ± SD, n = 10) after treatment (Z = -2.395, P < 0.05, two-sample paired Wilcoxon test). CONCLUSION: 1H-MRS can be used to quantify liver choline in vivo using unsuppressed water as an internal reference. Decreased liver choline concentrations are found in sodium selenite-treated rabbits undergoing liver cell apoptosis.展开更多
Direct photon to chemical energy conversion using semiconductor–electrocatalyst–electrolyte interfaces has been extensively investigated for more than a half century. Many studies have focused on screening materials...Direct photon to chemical energy conversion using semiconductor–electrocatalyst–electrolyte interfaces has been extensively investigated for more than a half century. Many studies have focused on screening materials for efficient photocatalysis. Photocatalytic efficiency has been improved during this period but is not sufficient for industrial commercialization. Detailed elucidation on the photocatalytic water splitting process leads to consecutive six reaction steps with the fundamental parameters involved: The photocatalysis is initiated involving photophysics derived from various semiconductor properties(1: photon absorption, 2: exciton separation). The generated charge carriers need to be transferred to surfaces effectively utilizing the interfaces(3: carrier diffusion, 4: carrier transport). Consequently, electrocatalysis finishes the process by producing products on the surface(5: catalytic efficiency, 6: mass transfer of reactants and products). Successful photocatalytic water splitting requires the enhancement of efficiency at each stage. Most critically, a fundamental understanding of the interfacial phenomena is highly desired for establishing "photocatalysis by design" concepts, where the kinetic bottleneck within a process is identified by further improving the specific properties of photocatalytic materials as opposed to blind material screening. Theoretical modeling using the identified quantitative parameters can effectively predict the theoretically attainable photon-conversion yields. This article provides an overview of the state-of-the-art theoretical understanding of interfacial problems mainly developed in our laboratory.Photocatalytic water splitting(especially hydrogen evolution on metal surfaces) was selected as a topic,and the photophysical and electrochemical processes that occur at semiconductor–metal, semiconductor–electrolyte and metal–electrolyte interfaces are discussed.展开更多
Historical optical data are combined on the BL Lac object OQ 530. Verifying the existence of correlations among the flux variations in different bands serves as an important tool to investigate emission processes. To ...Historical optical data are combined on the BL Lac object OQ 530. Verifying the existence of correlations among the flux variations in different bands serves as an important tool to investigate emission processes. To examine the possible existence of a lag between variations in different optical bands from this source, a statistical analysis is performed through the discrete correlation function (DCF) method and the z -transformed discrete correlation function (ZDCF) method. Monte Carlo simulations called "flux redistribution/random subset selection" (FR/RSS) are performed to obtain statistically meaningful values for the cross-correlation time lags and their related uncertainties. The analysis confirms that the variations in different optical light curves are strongly correlated, with zero-lag within the errors. Long term variability of color indexes is also analyzed. The result suggests a strong correlation between color index and brightness. A clear bluer-when-brighter chromatism is found, in the sense that the spectrum steepens as the brightness decreases.展开更多
Balancing the risks and benefits of organophosphate pesticides(OPs)on human and environmental health relies partly on their accurate measurement.A highly sensitive fluorescence anti-quenching multi-residue bio-barcode...Balancing the risks and benefits of organophosphate pesticides(OPs)on human and environmental health relies partly on their accurate measurement.A highly sensitive fluorescence anti-quenching multi-residue bio-barcode immunoassay was developed to detect OPs(triazophos,parathion,and chlorpyrifos)in apples,turnips,cabbages,and rice.Gold nanoparticles were functionalized with monoclonal antibodies against the tested OPs.DNA oligonucleotides were complementarily hybridized with an RNA fluorescent label for signal amplification.The detection signals were generated by DNA-RNA hybridization and ribonuclease H dissociation of the fluorophore.The resulting fluorescence signal enables multiplexed quantification of triazophos,parathion,and chlorpyrifos residues over the concentration range of 0.01-25,0.01-50,and 0.1-50 ng/mL with limits of detection of 0.014,0.011,and 0.126 ng/mL,respectively.The mean recovery ranged between 80.3% and 110.8% with relative standard deviations of 7.3%-17.6%,which correlate well with results obtained by liquid chromatography-tandem mass spectrometry(LC-MS/MS).The proposed bio-barcode immunoassay is stable,reproducible and reliable,and is able to detect low residual levels of multi-residue OPs in agricultural products.展开更多
The recombination loss of photo-carriers in photocatalytic systems fatally determines the energy conversion efficiency of photocatalysts.In this work,an electrostatic field was used to inhibit the recombination of pho...The recombination loss of photo-carriers in photocatalytic systems fatally determines the energy conversion efficiency of photocatalysts.In this work,an electrostatic field was used to inhibit the recombination of photo-carriers in photocatalysts by separating photo-holes and photo-electrons in space.As a model structure,(010)facet-exposed BiVO_(4)nanowires were grown on PDMS-insulated piezo-substrate of piezoelectric transducer(PZT).The PZT substrate will generate an electrostatic field under a certain stress,and the photocatalytic behavior of BiVO_(4) nanowires is influenced by the electrostatic field.Our results showed that the photocatalytic performance of the BiVO_(4) nanowires in CO_(2)reduction in the negative electrostatic field is enhanced to 5.5-fold of that without electrostatic field.Moreover,the concentration of methane in the products was raised from 29% to 64%.The enhanced CO_(2) reduction efficiency is mainly attributed to the inhibited recombination loss of photo-carriers in the BiVO_(4) nanowires.The increased energy of photo-carriers and the enhanced surface absorption to polar molecules,which are CO in this case,were also play important roles in improving the photocatalytic activity of the photocatalyst and product selectivity.This work proposed an effective strategy to improve photo-carriers separation/transfer dynamics in the photocatalytic systems,which will also be a favorable reference for photovoltaic and photodetecting devices.展开更多
The license plate recognition system(LPRS)has been widely adopted in daily life due to its efficiency and high accuracy.Deep neural networks are commonly used in the LPRS to improve the recognition accuracy.However,re...The license plate recognition system(LPRS)has been widely adopted in daily life due to its efficiency and high accuracy.Deep neural networks are commonly used in the LPRS to improve the recognition accuracy.However,researchers have found that deep neural networks have their own security problems that may lead to unexpected results.Specifically,they can be easily attacked by the adversarial examples that are generated by adding small perturbations to the original images,resulting in incorrect license plate recognition.There are some classic methods to generate adversarial examples,but they cannot be adopted on LPRS directly.In this paper,we modify some classic methods to generate adversarial examples that could mislead the LPRS.We conduct extensive evaluations on the HyperLPR system and the results show that the system could be easily attacked by such adversarial examples.In addition,we show that the generated images could also attack the black-box systems;we show some examples that the Baidu LPR system also makes incorrect recognitions.We hope this paper could help improve the LPRS by realizing the existence of such adversarial attacks.展开更多
Results Sixty-one cancer survivors and 183 matched non-cancer patients were screened from 2,828 COVID-19 infected patients admitted to 4 hospitals in Wuhan,China.The median ages of the cancer survivor cohort and non-c...Results Sixty-one cancer survivors and 183 matched non-cancer patients were screened from 2,828 COVID-19 infected patients admitted to 4 hospitals in Wuhan,China.The median ages of the cancer survivor cohort and non-cancer patient cohort were 64.0(55.0–73.0)and 64.0(54.0–73.5),respectively(P=0.909).Cancer survivors reported a higher incidence of symptom onset than non-cancer patients.Fever(80.3%vs.65.0%;P=0.026)was the most prevalent symptom,followed by cough(65.6%vs.37.7%;P<0.001),myalgia,and fatigue(45.9%vs.13.6%;P<0.001).The risks of the development of severe events(adjusted hazard ratio[AHR]=1.25;95%confidence interval[CI]:0.76–2.06;P=0.378)and mortality(relative risk[RR]=0.90,95%CI:0.79–1.04;P=0.416)in the cancer survivor cohort were comparable to those of the matched non-cancer patient cohort.However,the cancer survivor cohort showed a higher incidence of secondary infection(52.5%vs.30.1%;RR=1.47,95%CI:1.11–1.95;P=0.002)and a prolonged viral RNA shedding duration(32 days[IQR 26.0–46.0]vs.24.0 days[IQR 18.0–33.0];AHR=0.54;95%CI:0.38–0.80;P<0.05).Conclusion Compared to non-cancer patients,cancer survivors with COVID-19 exhibited a higher incidence of secondary infection,a prolonged period of viral shedding,but comparable risks of the development of severe events and mortality.It is helpful for clinicians to take tailored measures to treat cancer survivors with COVID-19.展开更多
There are two different dust storms in Northeast China, normal dust and alkali dust, from Kerqin sand land and Songnen saline land. As well as visible damages of the dust storms, there are some invisible influences. T...There are two different dust storms in Northeast China, normal dust and alkali dust, from Kerqin sand land and Songnen saline land. As well as visible damages of the dust storms, there are some invisible influences. The authors provide evidences that the bacteria carried by dusts from remote area should not be ignored, but the damages of the alkali dusts are still not clear.展开更多
To measure the equivalent ratio distribution of the two-stage lean premixed(DLP)flame,we propose using acetone/toluene planar laser-induced fluorescence(PLIF)technology to simultaneously measure the concentrations of ...To measure the equivalent ratio distribution of the two-stage lean premixed(DLP)flame,we propose using acetone/toluene planar laser-induced fluorescence(PLIF)technology to simultaneously measure the concentrations of the two components.Appropriate excitation laser wavelength and filters are used to assess the influence of acetone and toluene on each other’s fluorescence signal at room temperature.Experimental results show that acetone has a strong absorption effect on toluene’s fluorescence signal,the effective absorption cross-section is 5.77×10-20 cm-2.Acetone has an obvious quenching effect on the toluene fluorescence signal,and the Stern–Volmer coefficient is 0.50 kPa-1.The collisions between the molecules of toluene and acetone will lead to the enhancement of the fluorescence signal of acetone,and the enhancement coefficient is exponential with the acetone’s concentration.The quantitative relationship between the fluorescence intensity and the concentrations of the two tracers is obtained by establishing the photophysical model of toluene and acetone’s fluorescence signals.展开更多
Gastric cancer(GC)was referred to a malignant tumor of the digestive tract originating from the epithelium of gastric mucosa.Transcription factor DLX5 was verified as an oncogene in various types of tumors,while miR-3...Gastric cancer(GC)was referred to a malignant tumor of the digestive tract originating from the epithelium of gastric mucosa.Transcription factor DLX5 was verified as an oncogene in various types of tumors,while miR-376a-3p was speculated as a tumor suppressor.Based on the bioinformatics database,we hypothesized that miR-376a participated in the regulation of GC development by targeting DLX5.Compared with adjacent tissue,a significant increase of DLX5 expression was determined in GC tissues,but the expression level is significantly reduced in miR-376a.Similar expression signature of DLX5 and miR-376a was also determined between 4 GC cells(HGC,SGC,MGC,and AGS cell lines)and GES cell line.The level of DLX5 was notably reduced in HGC and MGC cell lines after miR-376a-3p overexpression,and increased after miR-376a-3p inhibition.Then,the inhibition role of miR-376a-3p on DLX5 was further proved by dualluciferase reporter assay.Gain-of-function experiments showed that upregulation of miR-376a-3p in GC cells could inhibit the ability of epithelial-mesenchymal transition,proliferation,and invasion,and enhance the GC cell apoptosis level.However,these roles of miR-376a-3p could be abolished by DLX5 overexpression.This study confirmed that reduction of miR-376a-3p expression level in GC cells would lead to the increase in cell growth and invasion,indicating that upregulation of miR-376a-3p might have a potential therapeutic role on GC.展开更多
The origin of ultra high energy cosmic rays (UHECRs) is still an open question in astroparticle physics. TeV blazars are a small group of active galactic nuclei (AGNs). They all have been observed in TeV gamma ray ban...The origin of ultra high energy cosmic rays (UHECRs) is still an open question in astroparticle physics. TeV blazars are a small group of active galactic nuclei (AGNs). They all have been observed in TeV gamma ray band, and show violent variabilities in flux at all wavelengths. So it is believed that they have abilities to produce UHECRs. To judge whether the TeV blazars can be the candidates of the origin of UHECRs, we collect the information of emission region of 38 TeV blazars, and estimate the maximum energy that the charged particle can be accelerated there. The results show that TeV blazars have abilities to accelerate cosmic rays to the energy above 1018?eV, some even higher than 1020?eV, and they may be the sources of UHECRs.展开更多
We report the detection of aγ-ray bubble spanning at least 100deg2 in ultra-high energy(UHE)up to a few PeV in the direction of the star-forming region Cygnus X,implying the presence super PeVatron(s)accelerating pro...We report the detection of aγ-ray bubble spanning at least 100deg2 in ultra-high energy(UHE)up to a few PeV in the direction of the star-forming region Cygnus X,implying the presence super PeVatron(s)accelerating protons to at least 10 PeV.A log-parabola form with the photon indexΓ(E)=(2.71±0.02)+(0.11±0.02)×log10(E/10 TeV)is found fitting the gamma-ray energy spectrum of the bubble well.UHE sources,“hot spots”correlated with very massive molecular clouds,and a quasi-spherical amorphousγ-ray emitter with a sharp central brightening are observed in the bubble.In the core of~0.5°,spatially associating with a region containing massive OB association(Cygnus OB2)and a microquasar(Cygnus X-3),as well as previously reported multi-TeV sources,an enhanced concentration of UHEγ-rays is observed with 2 photons at energies above 1 PeV.The general feature of the bubble,the morphology,and the energy spectrum,are reasonably reproduced by the assumption of a particle accelerator in the core,continuously injecting protons into the ambient medium.展开更多
Flame features and dynamics are important to the explanation and prediction of a lean blowout(LBO)phenomenon.In this paper,recognition of near-LBO flame features and oscillation characterization methods were proposed ...Flame features and dynamics are important to the explanation and prediction of a lean blowout(LBO)phenomenon.In this paper,recognition of near-LBO flame features and oscillation characterization methods were proposed based on flame spectroscopic images.High-speed planar laser-induced fluorescence measurements of OH were used to capture unique dynamic features such as the local extinction and reignition feature and entrained reactant pockets.The Zernike moment demonstrated a good performance in recognition of stability and near-LBO conditions,though the geometric moment had more advantages to characterize frequency characteristics.Low-frequency oscillations,especially at the obvious self-excited oscillation frequency around 200 Hz,were found when approaching an LBO condition,which can be expected to be used as a novel prediction characteristic parameter of the flameout limit.Proper orthogonal decomposition(POD)and dynamic mode decomposition(DMD)were used to conduct dynamic analysis of near-LBO flames.POD modes spectra showed the unique frequency characteristics of stable and near-LBO flames,which were basically in line with those at the heat-release frequency.The primary POD modes demonstrated that the radial vibration mode dominated in a stable flame,while the rotation mode was found to exist in a near-LBO flame.Analysis of modal decomposition showed that flame shedding and agminated entrained reactant pockets were responsible for generating self-excited flame oscillations.展开更多
The Large High Altitude Air Shower Observatory(LHAASO)has three sub-arrays,KM2A,WCDA,and WFCTA.The flux variations of cosmic ray air showers were studied by analyzing the KM2A data during a thunderstorm on June 10,202...The Large High Altitude Air Shower Observatory(LHAASO)has three sub-arrays,KM2A,WCDA,and WFCTA.The flux variations of cosmic ray air showers were studied by analyzing the KM2A data during a thunderstorm on June 10,2021.The number of shower events that meet the trigger conditions increases significantly in atmospheric electric fields,with a maximum fractional increase of 20%.The variations in trigger rates(increases or decreases)were found to be strongly dependent on the primary zenith angle.The flux of secondary particles increased significantly,following a trend similar to that of shower events.To better understand the observed behavior,Monte Carlo simulations were performed with CORSIKA and G4KM2A(a code based on GEANT4).We found that the experimental data(in saturated negative fields)were in good agreement with the simulations,assuming the presence of a uniform electric field of-700 V/cm with a thickness of 1500 m in the atmosphere above the observation level.Due to the acceleration/deceleration by the atmospheric electric field,the number of secondary particles with energy above the detector threshold was modified,resulting in the changes in shower detection rate.展开更多
Dear Editor,The conductive nanomaterials,such as carbon nanotubes(CNTs),have attracted much attention in biomedical applications.Particularly,it has been found that CNTs can promote the electrical activity of cardiomy...Dear Editor,The conductive nanomaterials,such as carbon nanotubes(CNTs),have attracted much attention in biomedical applications.Particularly,it has been found that CNTs can promote the electrical activity of cardiomyocytes,but little is known about the mechanism.^(1,2)To better understand the CNTs’biological effects on cardiomyocytes and the underlying mechanism.展开更多
Miniaturized gas pumps based on electromagnetic effect have been intensively studied and widely applied in industries.However,the electromagnetic effect-based gas pumps normally have large sizes,high levels of noises ...Miniaturized gas pumps based on electromagnetic effect have been intensively studied and widely applied in industries.However,the electromagnetic effect-based gas pumps normally have large sizes,high levels of noises and high power consumption,thus they are not suitable for wearable/portable applications.Herein,we propose a high-flowrate and high-pressure load valveless piezoelectric micropump with dimensions of 16 mm*16 mm*5 mm.The working frequency,vibration mode and displacement of the piezoelectric actuator,the velocity of gas flow,and the volume flowrate of the micropump are analyzed using the finite element analysis method.The maximum vibration amplitude of the piezoelectric actuator reaches~29.4μm.The output gas flowrate of the pump is approximately 135 mL/min,and the maximum output pressure exceeds 40 kPa.Then,a prototype of the piezoelectric micropump is fabricated.Results show that performance of the micropump is highly consistent with the numerical analysis with a high flowrate and pressure load,demonstrated its great potential for wearable/portable applications,especially for blood pressure monitoring.展开更多
To reveal the physical mechanism of laser ablation and establish the prediction model for figuring the surface of fused silica, a multi-physical transient numerical model coupled with heat transfer and fluid flow was ...To reveal the physical mechanism of laser ablation and establish the prediction model for figuring the surface of fused silica, a multi-physical transient numerical model coupled with heat transfer and fluid flow was developed under pulsed CO_2 laser irradiation. The model employed various heat transfer and hydrodynamic boundary and thermomechanical properties for assisting the understanding of the contributions of Marangoni convention,gravitational force, vaporization recoil pressure, and capillary force in the process of laser ablation and better prediction of laser processing. Simulation results indicated that the vaporization recoil pressure dominated the formation of the final ablation profile. The ablation depth increased exponentially with pulse duration and linearly with laser energy after homogenous evaporation. The model was validated by experimental data of pulse CO_2 laser ablation of fused silica. To further investigate laser beam figuring, local ablation by varying the overlap rate and laser energy was conducted, achieving down to 4 nm homogenous ablation depth.展开更多
基金The National Natural Science Foundation of China,No.30570480
文摘AIM: To study liver cell apoptosis caused by the toxicity of selenium and observe the alteration of choline compounds using in vitro 9.4T high resolution magnetic resonance spectroscopy. METHODS: Twenty male Wistar rats were randomly divided into two groups. The rats in the treatment group were intraperitoneally injected with sodium selenite and the control group with distilled water. All rats were sacrifi ced and the livers were dissected. 1H-MRS data were collected using in vitro 9.4T high resolution magnetic resonance spectrometer. Spectra were processed using XWINNMR and MestRe-c 4.3. HE and TUNEL staining was employed to detect and confi rm the change of liver cells. RESULTS: Good 1H-MR spectra of perchloric acid extract from liver tissue of rats were obtained. The conventional metabolites were detected and assigned. Concentrations of different ingredient choline compounds in treatment group vs control group were as follows: total choline compounds,5.08 ± 0.97 mmol/L vs 3.81 ± 1.16 mmol/L (P = 0.05); and free choline,1.07 ± 0.23 mmol/L vs 0.65 ± 0.20 mmol/L (P = 0.00). However,there was no statistical signif icance between the two groups. The hepatic sinus and cellular structure of hepatic cells in treatmentgroup were abnormal. Apoptosis of hepatic cells was confi rmed by TUNEL assay. CONCLUSION: High dose selenium compounds can cause the rat liver lesion and induce cell apoptosis in vivo. High resolution 1H-MRS in vitro can detect diversified metabolism. The changing trend for different ingredient of choline compounds is not completely the same at early period of apoptosis.
基金Supported by Grants from Medical Scientific Research Foundation of Guangdong Province, China, No. B2008128National Natural Science Foundation of China, No. 30930027 and No. 60971075, in part
文摘AIM: To evaluate the feasibility of quantifying liver choline concentrations in both normal and apoptotic rabbit livers in vivo, using 1H magnetic resonance spectroscopy (1H-MRS). METHODS: 1H-MRS was performed in 18 rabbits using a 1.5T GE MR system with an eight-channel head/neck receiving coil. Fifteen rabbits were injected with sodium selenite at a dose of 10 μmol/kg to induce the liver cell apoptosis. Point-resolved spectroscopy sequencelocalized spectra were obtained from 10 livers once before and once 24 h after sodium selenite injection in vivo. T1 and T2 relaxation time of water and choline was measured separately in the livers of three healthy rabbits and three selenite-treated rabbits. Hematoxylin and eosin and dUTP-biotin nick end labeling (TUNEL) staining was used to detect and confirm apoptosis. Choline peak areas were measured relative to unsuppressed water using LCModel. Relaxation attenuation was corrected using the average of T1 and T2 relaxation time. The choline concentration was quantified using a formula, which was tested by a phantom with a known concentration. RESULTS: Apoptosis of hepatic cells was confirmed by TUNEL assay. In phantom experiment, the choline concentration (3.01 mmol/L), measured by 1H-MRS, was in good agreement with the actual concentration (3 mmol/L). The average T1 and T2 relaxation time of choline was 612 ± 15 ms and 74 ± 4 ms in the control group and 670 ± 27 ms and 78 ± 5 ms in apoptotic livers in vivo, respectively. Choline was quantified in 10 rabbits, once before and once after the injection with sodium selenite. The choline concentration decreased from 14.5 ± 7.57 mmol/L before sodium selenite injection to 10.8 ± 6.58 mmol/L (mean ± SD, n = 10) after treatment (Z = -2.395, P < 0.05, two-sample paired Wilcoxon test). CONCLUSION: 1H-MRS can be used to quantify liver choline in vivo using unsuppressed water as an internal reference. Decreased liver choline concentrations are found in sodium selenite-treated rabbits undergoing liver cell apoptosis.
基金supported by funding from King Abdullah University of Science and Technology(KAUST)
文摘Direct photon to chemical energy conversion using semiconductor–electrocatalyst–electrolyte interfaces has been extensively investigated for more than a half century. Many studies have focused on screening materials for efficient photocatalysis. Photocatalytic efficiency has been improved during this period but is not sufficient for industrial commercialization. Detailed elucidation on the photocatalytic water splitting process leads to consecutive six reaction steps with the fundamental parameters involved: The photocatalysis is initiated involving photophysics derived from various semiconductor properties(1: photon absorption, 2: exciton separation). The generated charge carriers need to be transferred to surfaces effectively utilizing the interfaces(3: carrier diffusion, 4: carrier transport). Consequently, electrocatalysis finishes the process by producing products on the surface(5: catalytic efficiency, 6: mass transfer of reactants and products). Successful photocatalytic water splitting requires the enhancement of efficiency at each stage. Most critically, a fundamental understanding of the interfacial phenomena is highly desired for establishing "photocatalysis by design" concepts, where the kinetic bottleneck within a process is identified by further improving the specific properties of photocatalytic materials as opposed to blind material screening. Theoretical modeling using the identified quantitative parameters can effectively predict the theoretically attainable photon-conversion yields. This article provides an overview of the state-of-the-art theoretical understanding of interfacial problems mainly developed in our laboratory.Photocatalytic water splitting(especially hydrogen evolution on metal surfaces) was selected as a topic,and the photophysical and electrochemical processes that occur at semiconductor–metal, semiconductor–electrolyte and metal–electrolyte interfaces are discussed.
基金Supported by the National Natural Science Foundation of China (Grant No. 10975145)funded by Fuyang Normal College, the Research Foundation of the Department of Education of Anhui Province (KJ2010B159)
文摘Historical optical data are combined on the BL Lac object OQ 530. Verifying the existence of correlations among the flux variations in different bands serves as an important tool to investigate emission processes. To examine the possible existence of a lag between variations in different optical bands from this source, a statistical analysis is performed through the discrete correlation function (DCF) method and the z -transformed discrete correlation function (ZDCF) method. Monte Carlo simulations called "flux redistribution/random subset selection" (FR/RSS) are performed to obtain statistically meaningful values for the cross-correlation time lags and their related uncertainties. The analysis confirms that the variations in different optical light curves are strongly correlated, with zero-lag within the errors. Long term variability of color indexes is also analyzed. The result suggests a strong correlation between color index and brightness. A clear bluer-when-brighter chromatism is found, in the sense that the spectrum steepens as the brightness decreases.
基金supported by the Central Public Interest Scientific Institution Basal Research Fund for the Chinese Academy of Agricultural Sciences(Grant No.:Y2021PT05)National Institute of Environmental Health Science Superfund Research Program(Grant No.:P42 ES004699)+1 种基金National Academy of Sciences(Subaward No.:2000009144)Ningbo Innovation Project for Agro-Products Quality and Safety(Grant No.:2019CXGC007).
文摘Balancing the risks and benefits of organophosphate pesticides(OPs)on human and environmental health relies partly on their accurate measurement.A highly sensitive fluorescence anti-quenching multi-residue bio-barcode immunoassay was developed to detect OPs(triazophos,parathion,and chlorpyrifos)in apples,turnips,cabbages,and rice.Gold nanoparticles were functionalized with monoclonal antibodies against the tested OPs.DNA oligonucleotides were complementarily hybridized with an RNA fluorescent label for signal amplification.The detection signals were generated by DNA-RNA hybridization and ribonuclease H dissociation of the fluorophore.The resulting fluorescence signal enables multiplexed quantification of triazophos,parathion,and chlorpyrifos residues over the concentration range of 0.01-25,0.01-50,and 0.1-50 ng/mL with limits of detection of 0.014,0.011,and 0.126 ng/mL,respectively.The mean recovery ranged between 80.3% and 110.8% with relative standard deviations of 7.3%-17.6%,which correlate well with results obtained by liquid chromatography-tandem mass spectrometry(LC-MS/MS).The proposed bio-barcode immunoassay is stable,reproducible and reliable,and is able to detect low residual levels of multi-residue OPs in agricultural products.
基金financially supported by the National Natural Science Foundation of China(21607066,51972153)Natural Science Foundation of Gansu Province of China(21JR7RA469)the Fundamental Research Funds for the Central Universities(lzujbky-2021-76).
文摘The recombination loss of photo-carriers in photocatalytic systems fatally determines the energy conversion efficiency of photocatalysts.In this work,an electrostatic field was used to inhibit the recombination of photo-carriers in photocatalysts by separating photo-holes and photo-electrons in space.As a model structure,(010)facet-exposed BiVO_(4)nanowires were grown on PDMS-insulated piezo-substrate of piezoelectric transducer(PZT).The PZT substrate will generate an electrostatic field under a certain stress,and the photocatalytic behavior of BiVO_(4) nanowires is influenced by the electrostatic field.Our results showed that the photocatalytic performance of the BiVO_(4) nanowires in CO_(2)reduction in the negative electrostatic field is enhanced to 5.5-fold of that without electrostatic field.Moreover,the concentration of methane in the products was raised from 29% to 64%.The enhanced CO_(2) reduction efficiency is mainly attributed to the inhibited recombination loss of photo-carriers in the BiVO_(4) nanowires.The increased energy of photo-carriers and the enhanced surface absorption to polar molecules,which are CO in this case,were also play important roles in improving the photocatalytic activity of the photocatalyst and product selectivity.This work proposed an effective strategy to improve photo-carriers separation/transfer dynamics in the photocatalytic systems,which will also be a favorable reference for photovoltaic and photodetecting devices.
基金This work is supported by the National Natural Science Foundation of China under Grant Nos.U1636215,61902082the Guangdong Key R&D Program of China 2019B010136003National Key R&D Program of China 2019YFB1706003.
文摘The license plate recognition system(LPRS)has been widely adopted in daily life due to its efficiency and high accuracy.Deep neural networks are commonly used in the LPRS to improve the recognition accuracy.However,researchers have found that deep neural networks have their own security problems that may lead to unexpected results.Specifically,they can be easily attacked by the adversarial examples that are generated by adding small perturbations to the original images,resulting in incorrect license plate recognition.There are some classic methods to generate adversarial examples,but they cannot be adopted on LPRS directly.In this paper,we modify some classic methods to generate adversarial examples that could mislead the LPRS.We conduct extensive evaluations on the HyperLPR system and the results show that the system could be easily attacked by such adversarial examples.In addition,we show that the generated images could also attack the black-box systems;we show some examples that the Baidu LPR system also makes incorrect recognitions.We hope this paper could help improve the LPRS by realizing the existence of such adversarial attacks.
基金Supported by grants from the SGC’s Rapid Response Funding for Bilgateral Collaborative Emergence COVID-19 Project between China and Germany(No.C-0065)COVID-19 Emergency Project of Huazhong University of Science and Technology(No.2020kfyXGYJ062)Hepatobiliary and Pancreatic Cancer Grant,Hubei Chen Xiaoping Science and Technology Development Foundation(No.CXPJJH12000001-2020344).
文摘Results Sixty-one cancer survivors and 183 matched non-cancer patients were screened from 2,828 COVID-19 infected patients admitted to 4 hospitals in Wuhan,China.The median ages of the cancer survivor cohort and non-cancer patient cohort were 64.0(55.0–73.0)and 64.0(54.0–73.5),respectively(P=0.909).Cancer survivors reported a higher incidence of symptom onset than non-cancer patients.Fever(80.3%vs.65.0%;P=0.026)was the most prevalent symptom,followed by cough(65.6%vs.37.7%;P<0.001),myalgia,and fatigue(45.9%vs.13.6%;P<0.001).The risks of the development of severe events(adjusted hazard ratio[AHR]=1.25;95%confidence interval[CI]:0.76–2.06;P=0.378)and mortality(relative risk[RR]=0.90,95%CI:0.79–1.04;P=0.416)in the cancer survivor cohort were comparable to those of the matched non-cancer patient cohort.However,the cancer survivor cohort showed a higher incidence of secondary infection(52.5%vs.30.1%;RR=1.47,95%CI:1.11–1.95;P=0.002)and a prolonged viral RNA shedding duration(32 days[IQR 26.0–46.0]vs.24.0 days[IQR 18.0–33.0];AHR=0.54;95%CI:0.38–0.80;P<0.05).Conclusion Compared to non-cancer patients,cancer survivors with COVID-19 exhibited a higher incidence of secondary infection,a prolonged period of viral shedding,but comparable risks of the development of severe events and mortality.It is helpful for clinicians to take tailored measures to treat cancer survivors with COVID-19.
文摘There are two different dust storms in Northeast China, normal dust and alkali dust, from Kerqin sand land and Songnen saline land. As well as visible damages of the dust storms, there are some invisible influences. The authors provide evidences that the bacteria carried by dusts from remote area should not be ignored, but the damages of the alkali dusts are still not clear.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51536002,61405048,and 91441130)。
文摘To measure the equivalent ratio distribution of the two-stage lean premixed(DLP)flame,we propose using acetone/toluene planar laser-induced fluorescence(PLIF)technology to simultaneously measure the concentrations of the two components.Appropriate excitation laser wavelength and filters are used to assess the influence of acetone and toluene on each other’s fluorescence signal at room temperature.Experimental results show that acetone has a strong absorption effect on toluene’s fluorescence signal,the effective absorption cross-section is 5.77×10-20 cm-2.Acetone has an obvious quenching effect on the toluene fluorescence signal,and the Stern–Volmer coefficient is 0.50 kPa-1.The collisions between the molecules of toluene and acetone will lead to the enhancement of the fluorescence signal of acetone,and the enhancement coefficient is exponential with the acetone’s concentration.The quantitative relationship between the fluorescence intensity and the concentrations of the two tracers is obtained by establishing the photophysical model of toluene and acetone’s fluorescence signals.
基金This work was supported by the Nature Science Foundation of China(81972320).
文摘Gastric cancer(GC)was referred to a malignant tumor of the digestive tract originating from the epithelium of gastric mucosa.Transcription factor DLX5 was verified as an oncogene in various types of tumors,while miR-376a-3p was speculated as a tumor suppressor.Based on the bioinformatics database,we hypothesized that miR-376a participated in the regulation of GC development by targeting DLX5.Compared with adjacent tissue,a significant increase of DLX5 expression was determined in GC tissues,but the expression level is significantly reduced in miR-376a.Similar expression signature of DLX5 and miR-376a was also determined between 4 GC cells(HGC,SGC,MGC,and AGS cell lines)and GES cell line.The level of DLX5 was notably reduced in HGC and MGC cell lines after miR-376a-3p overexpression,and increased after miR-376a-3p inhibition.Then,the inhibition role of miR-376a-3p on DLX5 was further proved by dualluciferase reporter assay.Gain-of-function experiments showed that upregulation of miR-376a-3p in GC cells could inhibit the ability of epithelial-mesenchymal transition,proliferation,and invasion,and enhance the GC cell apoptosis level.However,these roles of miR-376a-3p could be abolished by DLX5 overexpression.This study confirmed that reduction of miR-376a-3p expression level in GC cells would lead to the increase in cell growth and invasion,indicating that upregulation of miR-376a-3p might have a potential therapeutic role on GC.
文摘The origin of ultra high energy cosmic rays (UHECRs) is still an open question in astroparticle physics. TeV blazars are a small group of active galactic nuclei (AGNs). They all have been observed in TeV gamma ray band, and show violent variabilities in flux at all wavelengths. So it is believed that they have abilities to produce UHECRs. To judge whether the TeV blazars can be the candidates of the origin of UHECRs, we collect the information of emission region of 38 TeV blazars, and estimate the maximum energy that the charged particle can be accelerated there. The results show that TeV blazars have abilities to accelerate cosmic rays to the energy above 1018?eV, some even higher than 1020?eV, and they may be the sources of UHECRs.
基金supported in China by the National Key R&D Program of China(2018YFA0404201,2018YFA0404202,2018YFA0404203,and 2018YFA0404204)the National Natural Science Foundation of China(12105294,12022502,12261160362,12205314,U1931201,and U2031105)+1 种基金the Youth Innovation Promotion Association of Chinese Academy of Sciences(2022010)in Thailand by the National Science and Technology Development Agency(NSTDA)and National Research Council of Thailand(NRCT):High-Potential Research Team Grant Program(N42A650868).
文摘We report the detection of aγ-ray bubble spanning at least 100deg2 in ultra-high energy(UHE)up to a few PeV in the direction of the star-forming region Cygnus X,implying the presence super PeVatron(s)accelerating protons to at least 10 PeV.A log-parabola form with the photon indexΓ(E)=(2.71±0.02)+(0.11±0.02)×log10(E/10 TeV)is found fitting the gamma-ray energy spectrum of the bubble well.UHE sources,“hot spots”correlated with very massive molecular clouds,and a quasi-spherical amorphousγ-ray emitter with a sharp central brightening are observed in the bubble.In the core of~0.5°,spatially associating with a region containing massive OB association(Cygnus OB2)and a microquasar(Cygnus X-3),as well as previously reported multi-TeV sources,an enhanced concentration of UHEγ-rays is observed with 2 photons at energies above 1 PeV.The general feature of the bubble,the morphology,and the energy spectrum,are reasonably reproduced by the assumption of a particle accelerator in the core,continuously injecting protons into the ambient medium.
基金supported by the Heilongjiang Provincial Natural Science Foundation of China(No.LH2021F028)。
文摘Flame features and dynamics are important to the explanation and prediction of a lean blowout(LBO)phenomenon.In this paper,recognition of near-LBO flame features and oscillation characterization methods were proposed based on flame spectroscopic images.High-speed planar laser-induced fluorescence measurements of OH were used to capture unique dynamic features such as the local extinction and reignition feature and entrained reactant pockets.The Zernike moment demonstrated a good performance in recognition of stability and near-LBO conditions,though the geometric moment had more advantages to characterize frequency characteristics.Low-frequency oscillations,especially at the obvious self-excited oscillation frequency around 200 Hz,were found when approaching an LBO condition,which can be expected to be used as a novel prediction characteristic parameter of the flameout limit.Proper orthogonal decomposition(POD)and dynamic mode decomposition(DMD)were used to conduct dynamic analysis of near-LBO flames.POD modes spectra showed the unique frequency characteristics of stable and near-LBO flames,which were basically in line with those at the heat-release frequency.The primary POD modes demonstrated that the radial vibration mode dominated in a stable flame,while the rotation mode was found to exist in a near-LBO flame.Analysis of modal decomposition showed that flame shedding and agminated entrained reactant pockets were responsible for generating self-excited flame oscillations.
基金Supported in China by National Key R&D program of China(2018YFA0404201,2018YFA0404202,2018YFA0404203,2018YFA0404204)NSFC(U2031101,11475141,12147208)in Thailand by RTA6280002 from Thailand Science Research and Innovation。
文摘The Large High Altitude Air Shower Observatory(LHAASO)has three sub-arrays,KM2A,WCDA,and WFCTA.The flux variations of cosmic ray air showers were studied by analyzing the KM2A data during a thunderstorm on June 10,2021.The number of shower events that meet the trigger conditions increases significantly in atmospheric electric fields,with a maximum fractional increase of 20%.The variations in trigger rates(increases or decreases)were found to be strongly dependent on the primary zenith angle.The flux of secondary particles increased significantly,following a trend similar to that of shower events.To better understand the observed behavior,Monte Carlo simulations were performed with CORSIKA and G4KM2A(a code based on GEANT4).We found that the experimental data(in saturated negative fields)were in good agreement with the simulations,assuming the presence of a uniform electric field of-700 V/cm with a thickness of 1500 m in the atmosphere above the observation level.Due to the acceleration/deceleration by the atmospheric electric field,the number of secondary particles with energy above the detector threshold was modified,resulting in the changes in shower detection rate.
基金supported by the National Natural Science Foundation of China(Grant Nos.31830030)National Key Research and Development Program of China(Grant Nos.2017YFA0106100)Joint Fund project of National Natural Science Foundation of China(Grant Nos.U21A20394).
文摘Dear Editor,The conductive nanomaterials,such as carbon nanotubes(CNTs),have attracted much attention in biomedical applications.Particularly,it has been found that CNTs can promote the electrical activity of cardiomyocytes,but little is known about the mechanism.^(1,2)To better understand the CNTs’biological effects on cardiomyocytes and the underlying mechanism.
基金This work was funded by the National Natural Science Foundation of China(No.61827086,61974037,62175045)the National Key R&D Program of China(No.2021YFB3602200)+2 种基金the NSFC-Zhejiang Joint Fund for the Integration of Industrialization and Information(No.U20A20172)the Zhejiang Province Key R&D programs(No.2021C05004,No.2023C01192)The work was supported by the Fundamental Research Funds for the Provincial Universities of Zhejiang(GK239909299001-001,GK229909299001-408).
文摘Miniaturized gas pumps based on electromagnetic effect have been intensively studied and widely applied in industries.However,the electromagnetic effect-based gas pumps normally have large sizes,high levels of noises and high power consumption,thus they are not suitable for wearable/portable applications.Herein,we propose a high-flowrate and high-pressure load valveless piezoelectric micropump with dimensions of 16 mm*16 mm*5 mm.The working frequency,vibration mode and displacement of the piezoelectric actuator,the velocity of gas flow,and the volume flowrate of the micropump are analyzed using the finite element analysis method.The maximum vibration amplitude of the piezoelectric actuator reaches~29.4μm.The output gas flowrate of the pump is approximately 135 mL/min,and the maximum output pressure exceeds 40 kPa.Then,a prototype of the piezoelectric micropump is fabricated.Results show that performance of the micropump is highly consistent with the numerical analysis with a high flowrate and pressure load,demonstrated its great potential for wearable/portable applications,especially for blood pressure monitoring.
基金supported by the National Basic Research Program(No.2016YFB1102704)the Youth Innovation Promotion Association,CAS
文摘To reveal the physical mechanism of laser ablation and establish the prediction model for figuring the surface of fused silica, a multi-physical transient numerical model coupled with heat transfer and fluid flow was developed under pulsed CO_2 laser irradiation. The model employed various heat transfer and hydrodynamic boundary and thermomechanical properties for assisting the understanding of the contributions of Marangoni convention,gravitational force, vaporization recoil pressure, and capillary force in the process of laser ablation and better prediction of laser processing. Simulation results indicated that the vaporization recoil pressure dominated the formation of the final ablation profile. The ablation depth increased exponentially with pulse duration and linearly with laser energy after homogenous evaporation. The model was validated by experimental data of pulse CO_2 laser ablation of fused silica. To further investigate laser beam figuring, local ablation by varying the overlap rate and laser energy was conducted, achieving down to 4 nm homogenous ablation depth.
