In this study,we attempted to investigate the spatial gradient distributions of thermal shock-induced damage to granite with respect to associated deterioration mechanisms.First,thermal shock experiments were conducte...In this study,we attempted to investigate the spatial gradient distributions of thermal shock-induced damage to granite with respect to associated deterioration mechanisms.First,thermal shock experiments were conducted on granite specimens by slowly preheating the specimens to high temperatures,followed by rapid cooling in tap water.Then,the spatial gradient distributions of thermal shock-induced damage were investigated by computed tomography(CT)and image analysis techniques.Finally,the influence of the preheating temperature on the spatial gradients of the damage was discussed.The results show that the thermal shock induced by rapid cooling can cause more damage to granite than that induced by slow cooling.The thermal shock induced by rapid cooling can cause spatial gradient distributions of the damage to granite.The damage near the specimen surface was at a maximum,while the damage inside the specimen was at a minimum.In addition,the preheating temperature can significantly influence the spatial gradient distributions of the thermal shock-induced damage.The spatial gradient distribution of damage increased as the preheating temperature increased and then decreased significantly over 600C.When the preheating temperature was sufficiently high(e.g.800C),the gradient can be ignored.展开更多
AIM To investigate the pathogenic effect ofSEB and D-GalN on liver and the protection ofcyclosporin A, the relationship between hepaticapoptosis and necrosis and the possiblemechanism of acute hepatic necrosis.METHODS...AIM To investigate the pathogenic effect ofSEB and D-GalN on liver and the protection ofcyclosporin A, the relationship between hepaticapoptosis and necrosis and the possiblemechanism of acute hepatic necrosis.METHODS After staphylococcal enterotoxin B(SEB ) mixed with D--galactosamine (D-GaiN )were injected intraperitoneally into Balb/c miceand those previously treated with cyclosporin A,blood samples were collected and livers wereisolated at 2, 6, 12 and 24 h. Patterns othepatocellular death were studiedmorphologically and biochemically, circulatingcytokines (TNF-a, IFN--y ) and mice mortalitywithin 24h was assessed.RESU’LTS The SEB could induce the typicalapoptotic changes of hepatocytes, the D-GaiNcould induce hepatocytes apoptosis anddegeneration at the same time, and the micehaving received the SEB + D-GaiN injectionsdeveloped apoptosis at 2 and 6 h, but after 12 hhepatocytes were characterized by severein jury, whereas all the examinations in thecyclosporin A treated mice were normal.CONCLUSION Hepatic cell apoptosis might berelated to necrosis, and massive hepatocyteapoptosis is likely the initiating step of acutehepatic necrosis in mice. The effects induced bySEB and D--GaiN on hepatocytes might bemediated by T cells, and could be prevented bycyclosporin A.展开更多
The low laser induced damage threshold of the KH2PO4 crystal seriously restricts the output power of inertial confinement fusion.The micro-waviness on the KH2PO4 surface processed by single point diamond turning has a...The low laser induced damage threshold of the KH2PO4 crystal seriously restricts the output power of inertial confinement fusion.The micro-waviness on the KH2PO4 surface processed by single point diamond turning has a significant influence on the damage threshold.In this paper,the influence of micro-waviness on the damage threshold of the KH2PO4 crystal and the chief sources introducing the micro-waviness are analysed based on the combination of the Fourier modal theory and the power spectrum density method.Research results indicate that among the sub-wavinesses with different characteristic spatial frequencies there exists the most dangerous frequency which greatly reduces the damage threshold,although it may not occupy the largest proportion in the original surface.The experimental damage threshold is basically consistent with the theoretical calculation.For the processing parameters used,the leading frequency of micro-waviness which causes the damage threshold to decrease is between 350-1 μm-1 and 30-1 μm-1,especially between 90-1 μm-1 and 200-1 μm-1.Based on the classification study of the time frequencies of microwaviness,we find that the axial vibration of the spindle is the chief source introducing the micro-waviness,nearly all the leading frequencies are related to the practical spindle frequency（about 6.68 Hz,400 r/min） and a special middle frequency（between 1.029 Hz and 1.143 Hz）.展开更多
The structural damage to vascular endothelial cell In a recent article in the journal Brain Injury, four potential hypotheses for delayed neurological disorders following lightning and electrical injury were suggested...The structural damage to vascular endothelial cell In a recent article in the journal Brain Injury, four potential hypotheses for delayed neurological disorders following lightning and electrical injury were suggested （Reisner, 2013）. The phenomenon of delayed neurodegenerative syndromes following lighting and electrical injury has been known since the early 1930s （Critchley, 1934）, but to the present day, the mechanisms involved have been poorly un- derstood. An initial and still plausible theory is that the electrical insult causes damage to the vascular structures feeding the spinal cord via damage to vascular endothelial cells （Farrell and Starr, 1968）.展开更多
Polished fused silica samples were etched for different durations by using hydrofluoric（HF） acid solution with HF concentrations in an ultrasonic field. Surface and subsurface polishing residues and molecular struct...Polished fused silica samples were etched for different durations by using hydrofluoric（HF） acid solution with HF concentrations in an ultrasonic field. Surface and subsurface polishing residues and molecular structure parameters before and after the etching process were characterized by using a fluorescence microscope and infrared（IR） spectrometer, respectively. The laser induced damage thresholds（LIDTs） of the samples were measured by using pulsed nanosecond laser with wavelength of 355 nm. The results showed that surface and subsurface polishing residues can be effectively reduced by the acid etching process, and the LIDTs of fused silica are significantly improved. The etching effects increased with the increase of the HF concentration from 5 wt.% to 40 wt.%. The amount of polishing residues decreased with the increase of the etching duration and then kept stable. Simultaneously, with the increase of the etching time, the mechanical strength and molecular structure were improved.展开更多
The protective effect of biphenyl dimethyl dicarboxylate (DDB) on chemically induced damages was studied in isolated suspended rat hepatocytes. The experimental results showed that DDB (200μg/106 cells) efficiently p...The protective effect of biphenyl dimethyl dicarboxylate (DDB) on chemically induced damages was studied in isolated suspended rat hepatocytes. The experimental results showed that DDB (200μg/106 cells) efficiently protected the hepatocytes against carbon tetrachloride (CC14 10 mrnol.L-1) and D-galactosamine (1 mmol.L-1) induced damages. Membranal lipid peroxidation (malondialdehyde, MDA formation) and glutamic pyruvic transaminase (GPT) release from the hepatocytes were markedly decreased. The damage of the cell surfaces of the hepatocytes were also reduced as seen under a scanning electron microscope (SEM). Pretreatment with DDB (300 mg-kg-1) orally ameliorated the reduction of liver glycogen and blood glucose caused by ip injection of D-galactosamine (800 mg-kg-1) in mice. When normal rats were given DDB 300 mg-kg-1 once daily for 10 d, the free ribosomal protein and RNA in the liver increased significantly. These results indicate that DDB is of beneficial effects on both damaged and normal hepatocytes.展开更多
Rare earth doped B2O3-Al2O3-SiO2 glass （RExBAS, x=5, 10, 20; RE=La, Sm） were prepared by solid state reaction method. Optical transmission spectra of such glass were characterized by ultraviolet spectrometers, and 1...Rare earth doped B2O3-Al2O3-SiO2 glass （RExBAS, x=5, 10, 20; RE=La, Sm） were prepared by solid state reaction method. Optical transmission spectra of such glass were characterized by ultraviolet spectrometers, and 1064 nm laser induced damage performance was investigated through the method of ＂1-on-1＂. The results indicated that there was a strong absorptive peak near 1064 nm in SmxBAS glass, the peak was enhanced with increasing x. While LaxBAS glass was transparent to 1064 nm laser, at the same time, the results of laser induced damage showed that the anti-laser induced damage performance of such glass was strengthened with the addition of rare earth oxide. Furthermore, the laser induced damage threshold （LIDT） of SmxBAS glass was significantly higher than that of LaxBAS glass. Consequently, Sm^3＋ doping was favor in the improvement of anti-laser induced damage performance for BAS glass.展开更多
The highly charged ion Ar^12＋ with an energy of 3 Me V is used for irradiating metallic glass （Cu47Zr45Al8）98.5Y1.5 and polycrystalline metallic W at the irradiation fluences of 1× 10^14 ions/cm2, 1 × 10^...The highly charged ion Ar^12＋ with an energy of 3 Me V is used for irradiating metallic glass （Cu47Zr45Al8）98.5Y1.5 and polycrystalline metallic W at the irradiation fluences of 1× 10^14 ions/cm2, 1 × 10^15 ions/cm^2 and 1 × 10^16 ions/cm^2. The main structure of metallic glass remains an amorphous phase under different irradiation fluences according to x-ray diffraction analysis. The scanning electron microscope observation on the morphologies indicates that no significant irradiation damage occurs on the surface and cross section of the metallic glass sample after different fluences of irradiation, while a large area of irregular cracks and holes were observed on the surface of metallic W at a fluence of 1 ×10^16 ions/cm^2, with cracks and channel impairments at a certain depth from the surface. The root-mean-square （rms） roughness of metallic glass increases with increasing fluence of Ar^12＋, while the reflectance decreases with increasing irradiation fluence. A nano-hardness test shows that the hardness of metallic glass decreases after irradiation. Under certain a higher capability of resistance to Ar^12＋ irradiation in conditions, metallic glass （Cu47 Zr45Al8 ）98.5 Y1.5 exhibits comparison with polycrystalline W.展开更多
Traumatic cerebral or spinal cord injury induced by military,traffic,and sports accidents,falls or environmental and anthropogenic catastrophes are among main causes of people mortality and disability,especially in yo...Traumatic cerebral or spinal cord injury induced by military,traffic,and sports accidents,falls or environmental and anthropogenic catastrophes are among main causes of people mortality and disability,especially in young and middle age men（Kobeissy,2015）.Axon transection,or axotomy,occurs in wounds and during surgery.展开更多
The present study was performed to determine the influence of lipid peroxidation and perturbance of Ca2+ homeostasis on liver damage induced by 2-chloro-1, 3-butadiene (CBD) and the protective effects of vitamin E in ...The present study was performed to determine the influence of lipid peroxidation and perturbance of Ca2+ homeostasis on liver damage induced by 2-chloro-1, 3-butadiene (CBD) and the protective effects of vitamin E in Wistar rats. Animals were given intraperitoneally different doses (8,40 or 200 mg·kg-1 daily) of CBD for 21 days, and the following dose-dependent events were observed: liver damage, significant increase in liver lipid peroxides, and decreases in activities of erythrocytic glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD). The pretreatment of rats with vitamin E (po 150 mg·kg-1) before administering CBD (iP 60 mg·kg-1 ) daily for 21 days prevented the following CBD-induced changes, the increase in serum cholylglycine (CG), hepatic LP, hepatic mitochondrion LP, hepatic oxidized glutathione (GSSG) (while the significant increase of reduced glutathione (GSH) was not affected) and the decrease in activities of erythrocytic SOD and hepatic mitochondrial calcium sequestration. These results suggest that lipid peroxidation and perturbance of Ca2+ homeostasis appear to contribute to the hepatotoxicity of CBD, and vitamin E might prevent the liver damage induced by CBD. The decrease in activities of GSH-Px and SOD in erythrocytes might be used as biomarkers for adverse effects of CBD on defense system against lipid peroxidation.展开更多
Authors have conducted experiments to measure blast induced rock mass damage at L＆T-（Singoli-Bhatwari Hydro-Power Project SBHP） Rudraprayag. Repetitive NX size rock core up to 5.0 m depth were taken from side wall ...Authors have conducted experiments to measure blast induced rock mass damage at L＆T-（Singoli-Bhatwari Hydro-Power Project SBHP） Rudraprayag. Repetitive NX size rock core up to 5.0 m depth were taken from side wall and face with triple tube core barrel drill. CR （core recovery） and RQD （rock quality designation） of the rock cores is computed to evaluate effect of blasting on the surrounding rock mass. RQD and CR values for the initial one meter from the line of excavation in each case reflect maximum damage due to blast. RQD for initial one meter reduced to as high as 40% of the average RQD. The rock samples were also tested using ultrasonic techniques. Ultrasonic tests on NX size core reveal that the 2.0 m of the zone surrounding the opening are adversely affected by the tunnel excavation blasting process. The ultrasonic velocities reduce to approx. 80% of the average values in the initial 0.5 m from the excavation line.展开更多
The KH2PO4 crystal is a key component in optical systems of inertial confinement fusion （ICF）. The microwaviness on a KH2PO4 crystal surface is strongly related to its damage threshold which is a key parameter for a...The KH2PO4 crystal is a key component in optical systems of inertial confinement fusion （ICF）. The microwaviness on a KH2PO4 crystal surface is strongly related to its damage threshold which is a key parameter for application. To study the laser induced damage mechanism caused by microwaviness, in this paper the near-field modulation properties of microwaviness to the incident wave are discussed by the Fourier modal method. Research results indicate that the microwaviness on the machined surface will distort the incident wave and thus lead to non-uniform distribution of the light intensity inside the crystal; in a common range of microwaviness amplitude, the light intensity modulation degree increases about 0.03 whenever the microwaviness amplitude increases 10 nm; 1 order diffraction efficiencies are the key factors responsible for light intensity modulation inside the crystal; the light intensity modulation is just around the microwaviness in the form of an evanescent wave, not inside the crystal when the microwaviness period is below 0.712μm; light intensity modulation degree has two extreme points in microwaviness periods of 1.064μm and 1.6μm, remains unchanged between periods of 3μm and 150μm, and descends above the period of 150μm to 920μm.展开更多
We present a fully three-dimensional kinetic framework for modeling intense short pulse lasers interacting with dielectric materials.Our work modifies the open-source particle-in-cell code EPOCH to include new models ...We present a fully three-dimensional kinetic framework for modeling intense short pulse lasers interacting with dielectric materials.Our work modifies the open-source particle-in-cell code EPOCH to include new models for photoionization and dielectric optical response.We use this framework to model the laser-induced damage of dielectric materials by fewcycle laser pulses.The framework is benchmarked against experimental results for bulk silica targets and then applied to model multi-layer dielectric mirrors with a sequence of simulations with varying laser fluence.This allows us to better understand the laser damage process by providing new insight into energy absorption,excited particle dynamics and nonthermal excited particle distributions.We compare common damage threshold metrics based on the energy density and excited electron density.展开更多
The laser-induced damage threshold(LIDT)of optical elements is a critical limitation in advancing nextgeneration spaceborne laser technologies.Transient mechanisms in multiple-pulse damage dynamics have been recognize...The laser-induced damage threshold(LIDT)of optical elements is a critical limitation in advancing nextgeneration spaceborne laser technologies.Transient mechanisms in multiple-pulse damage dynamics have been recognized,but significant gaps remain in understanding these processes.In this study,we introduce a practice time interval(Δt_(p))-dependent damage metric.Using a double-pulse double-probe experimental configuration,we systematically examine the double-pulse damage dynamics and relaxation process.The first pulse induces localized modifications that initiate a relaxation process,accumulating material damage caused by the subsequent pulse.Our results show that this relaxation lasts~500 ns for surface damage and is on a several millisecond scale for bulk damage.The second pulse induces more pronounced modifications and damage whenΔt_(p)is less than100 ns,dominated by nonlinear phenomena like multiphoton absorption due to temporally overlapping pulses.Conversely,forΔt_(p)>100 ns,thermal accumulation via phonon relaxation predominates.Additionally,the critical energy density for damage correlates positively with LIDT asΔt_(p)increases,reflecting the reduced thermal and mechanical stress influence.These findings highlight the dynamic competition between nonlinear and thermal effects in multiple-pulse laser interactions,providing practical strategies for designing optical components with high damage thresholds and developing high-performance optical systems.展开更多
A comparison is made of several plasma-induced damage（PID） measurement techniques.A novel PID mechanism using high-density plasma（HDP） inter-metal dielectric（IMD） deposition is proposed.The results of a design o...A comparison is made of several plasma-induced damage（PID） measurement techniques.A novel PID mechanism using high-density plasma（HDP） inter-metal dielectric（IMD） deposition is proposed.The results of a design of experiment（DOE） on Ar pre-clean minimizing PID are presented.For HDP oxide deposition,the plasma damage is minimal,assuring minimal exposure time of the metal line to the plasma using a maximal deposition to sputter ratio.This process induces less PID than classic SOG processing.Ar pre-clean induces minimal plasma damage using minimal process time,high ion energy and high plasma power.For metal etching,an HDP etch is compared to a reactive ion etch,and the impact of the individual process steps are identified by specialized antenna structures.The measurement results of charge pumping,breakdown voltage and gate oxide leakage correlate very well.On metal etching,the reactive ion etching induces less plasma damage than HDP etching.For both reactors, PID is induced only in the metal over-etch step.展开更多
Leakage currents accelerate surface degradation of metal contacts via small scale arcing across lubricating films,but recent observations suggest that metallic nanoparticle additives in lubricants may be useful to imp...Leakage currents accelerate surface degradation of metal contacts via small scale arcing across lubricating films,but recent observations suggest that metallic nanoparticle additives in lubricants may be useful to improve contact performance.These findings prompted a study that examined electrically induced surface pitting of steel contacts in the presence of several lubricating greases including some containing nanometer-sized colloidal silver(Ag)particles.Reciprocating rolling sphere-on-disk experiments were conducted under electro-tribological loads employing polyurea greases derived from mineral and synthetic base oils with and without additives.Friction forces and electrical resistance were monitored continuously during the tests;surface changes were characterized by means of optical spectroscopy,stylus profilometry,and scanning electron microscopy(SEM)including compositional analysis using energy dispersive spectroscopy(EDS).The observations demonstrate that surface pitting induced by arcing occurs mainly at the points were the rolling motion changes direction and that eroded metal is deposited along the wear grove.Micron-sized pits are formed which contain carbon and oxygen indicating that arcing causes decomposition of the hydrocarbon lubricants.Numerous findings indicate a significant inhibition of pitting is induced by the Ag nanoparticles;some greases containing other additives exhibit a similar,although less pronounced,effect.展开更多
Blasting is widely used in hard rock tunnel excavation but often deteriorates the mechanical properties of the rock mass,forming a disturbance zone associated with energy evolution in the surrounding rock.In high-stre...Blasting is widely used in hard rock tunnel excavation but often deteriorates the mechanical properties of the rock mass,forming a disturbance zone associated with energy evolution in the surrounding rock.In high-stress environments,this disturbance zone poses risks of engineering disasters like rock bursts.Previous studies confirm that optimizing the energy release process is an effective strategy for rock burst control.This research focuses on enhancing energy path optimization by analyzing parameters affecting the formation of the disturbance zone.Specifically,we conducted a sensitivity analysis of key blasting parameters,including caving hole spacing,caving blasting load,smooth blasting burden,hole spacing,and smooth blasting load.By exploring the impact of caving and smooth blasting under varied design conditions,we developed a method to control rock bursts through staged energy release,gradually disturbing the surrounding rock.Results indicate that aligning the disturbance zones induced by caving and smooth blasting can regulate the energy release process effectively,a staged and controlled energy release process is proposed to modulate the distribution and timing of strain energy dissipation,thereby reducing the risk of dynamic failure.This approach presents a novel method for managing rock burst tendencies in high-stress rock tunnel excavations.展开更多
Radiotherapy is an effective local tumor ablation modality that can be used for the treatment of hepatocellular carcinoma(HCC)in specific clinical situations.Tumor cell ablation is facilitated through targeted ionizin...Radiotherapy is an effective local tumor ablation modality that can be used for the treatment of hepatocellular carcinoma(HCC)in specific clinical situations.Tumor cell ablation is facilitated through targeted ionizing radiation to directly induce DNA damage in cancer cells,which typically have dysfunctional DNA repair systems.In addition to direct tumor ablation,radiotherapy can also induce immunogenic cell death,release tumor-associated neoantigens,and promote dendritic cell activation.This type of immunogenic cell death can also significantly alter the tumor microenvironment,enhancing T-cell infiltration and reducing tumor-associated immune suppression.展开更多
Objective To investigate the protective effect of Pglycoprotein up-regulated by ulinastatin(UTI)on HK-2cells during paraquat(PQ)-induced injury and its underlying mechanisms.Methods The research was divided into two p...Objective To investigate the protective effect of Pglycoprotein up-regulated by ulinastatin(UTI)on HK-2cells during paraquat(PQ)-induced injury and its underlying mechanisms.Methods The research was divided into two parts.The first part of the research was divided into normal control group,PQ group,UTI+PQ group,UTI control group.The second part of the research was divided into negative virus group(including展开更多
To assess the long-term durability of waste-modified binder and asphalt mixtures as sustainable pavement solutions,their performance against the most dominant environmentally induced distresses in the extreme weather ...To assess the long-term durability of waste-modified binder and asphalt mixtures as sustainable pavement solutions,their performance against the most dominant environmentally induced distresses in the extreme weather environments is studied.This is critical for utilization of such solutions since many roads can be subject to flood,high UV and extreme temperatures.This review focuses on crumb rubber modified binder(CRMB)and recycled plastic-modified binder(RPMB)to enhance their performance predictability and support their broader use in pavements.While the immediate benefits are well-documented,a focused review on the mechanisms of environmental degradation and their impact on performance is lacking.CRMB exhibits unique ageing mechanisms,displaying resistance to oxidative,thermal,and UV ageing,offering promise for enhancing asphalt durability in harsh environments.In contrast,when exposed to UV,RPMB tends to present a complex interplay of factors influenced by polymer type,dosage,and environmental conditions that variability would affect the reliability of the product and thus suggests the need for further research.Moisture-induced distress in CRMB and RPMB asphalt mixtures is also considered,highlighting the challenges and opportunities for improving moisture susceptibility of these binders.In the literature,chemical interaction between crumb rubber and binder enhances aggregate adhesion,while undissolved crumb rubber particles may hinder it;however,consensus is lacking on their collective impact alongside other mixture parameters on the moisture resistance of asphalt.Asphalt mixtures with recycled plastics have shown acceptable moisture resistance;however,further research is needed to understand the interplay between recycled plastic properties(polarity,melting point,chemical structure)and mixture characteristics(plastic content,mixing method,temperature)to enhance reliability.展开更多
基金funded by the National Natural Science Foundation of China,China(Grant Nos.51778021,51627812 and 51678403)。
文摘In this study,we attempted to investigate the spatial gradient distributions of thermal shock-induced damage to granite with respect to associated deterioration mechanisms.First,thermal shock experiments were conducted on granite specimens by slowly preheating the specimens to high temperatures,followed by rapid cooling in tap water.Then,the spatial gradient distributions of thermal shock-induced damage were investigated by computed tomography(CT)and image analysis techniques.Finally,the influence of the preheating temperature on the spatial gradients of the damage was discussed.The results show that the thermal shock induced by rapid cooling can cause more damage to granite than that induced by slow cooling.The thermal shock induced by rapid cooling can cause spatial gradient distributions of the damage to granite.The damage near the specimen surface was at a maximum,while the damage inside the specimen was at a minimum.In addition,the preheating temperature can significantly influence the spatial gradient distributions of the thermal shock-induced damage.The spatial gradient distribution of damage increased as the preheating temperature increased and then decreased significantly over 600C.When the preheating temperature was sufficiently high(e.g.800C),the gradient can be ignored.
文摘AIM To investigate the pathogenic effect ofSEB and D-GalN on liver and the protection ofcyclosporin A, the relationship between hepaticapoptosis and necrosis and the possiblemechanism of acute hepatic necrosis.METHODS After staphylococcal enterotoxin B(SEB ) mixed with D--galactosamine (D-GaiN )were injected intraperitoneally into Balb/c miceand those previously treated with cyclosporin A,blood samples were collected and livers wereisolated at 2, 6, 12 and 24 h. Patterns othepatocellular death were studiedmorphologically and biochemically, circulatingcytokines (TNF-a, IFN--y ) and mice mortalitywithin 24h was assessed.RESU’LTS The SEB could induce the typicalapoptotic changes of hepatocytes, the D-GaiNcould induce hepatocytes apoptosis anddegeneration at the same time, and the micehaving received the SEB + D-GaiN injectionsdeveloped apoptosis at 2 and 6 h, but after 12 hhepatocytes were characterized by severein jury, whereas all the examinations in thecyclosporin A treated mice were normal.CONCLUSION Hepatic cell apoptosis might berelated to necrosis, and massive hepatocyteapoptosis is likely the initiating step of acutehepatic necrosis in mice. The effects induced bySEB and D--GaiN on hepatocytes might bemediated by T cells, and could be prevented bycyclosporin A.
基金Project supported by the National Natural Science Foundation of China (Grant No. 50875066)
文摘The low laser induced damage threshold of the KH2PO4 crystal seriously restricts the output power of inertial confinement fusion.The micro-waviness on the KH2PO4 surface processed by single point diamond turning has a significant influence on the damage threshold.In this paper,the influence of micro-waviness on the damage threshold of the KH2PO4 crystal and the chief sources introducing the micro-waviness are analysed based on the combination of the Fourier modal theory and the power spectrum density method.Research results indicate that among the sub-wavinesses with different characteristic spatial frequencies there exists the most dangerous frequency which greatly reduces the damage threshold,although it may not occupy the largest proportion in the original surface.The experimental damage threshold is basically consistent with the theoretical calculation.For the processing parameters used,the leading frequency of micro-waviness which causes the damage threshold to decrease is between 350-1 μm-1 and 30-1 μm-1,especially between 90-1 μm-1 and 200-1 μm-1.Based on the classification study of the time frequencies of microwaviness,we find that the axial vibration of the spindle is the chief source introducing the micro-waviness,nearly all the leading frequencies are related to the practical spindle frequency（about 6.68 Hz,400 r/min） and a special middle frequency（between 1.029 Hz and 1.143 Hz）.
文摘The structural damage to vascular endothelial cell In a recent article in the journal Brain Injury, four potential hypotheses for delayed neurological disorders following lightning and electrical injury were suggested （Reisner, 2013）. The phenomenon of delayed neurodegenerative syndromes following lighting and electrical injury has been known since the early 1930s （Critchley, 1934）, but to the present day, the mechanisms involved have been poorly un- derstood. An initial and still plausible theory is that the electrical insult causes damage to the vascular structures feeding the spinal cord via damage to vascular endothelial cells （Farrell and Starr, 1968）.
基金Project supported by the China Postdoctoral Science Foundation(Grant No.2016M592709)the National Natural Science Foundation of China(Grant No.51535003)
文摘Polished fused silica samples were etched for different durations by using hydrofluoric（HF） acid solution with HF concentrations in an ultrasonic field. Surface and subsurface polishing residues and molecular structure parameters before and after the etching process were characterized by using a fluorescence microscope and infrared（IR） spectrometer, respectively. The laser induced damage thresholds（LIDTs） of the samples were measured by using pulsed nanosecond laser with wavelength of 355 nm. The results showed that surface and subsurface polishing residues can be effectively reduced by the acid etching process, and the LIDTs of fused silica are significantly improved. The etching effects increased with the increase of the HF concentration from 5 wt.% to 40 wt.%. The amount of polishing residues decreased with the increase of the etching duration and then kept stable. Simultaneously, with the increase of the etching time, the mechanical strength and molecular structure were improved.
文摘The protective effect of biphenyl dimethyl dicarboxylate (DDB) on chemically induced damages was studied in isolated suspended rat hepatocytes. The experimental results showed that DDB (200μg/106 cells) efficiently protected the hepatocytes against carbon tetrachloride (CC14 10 mrnol.L-1) and D-galactosamine (1 mmol.L-1) induced damages. Membranal lipid peroxidation (malondialdehyde, MDA formation) and glutamic pyruvic transaminase (GPT) release from the hepatocytes were markedly decreased. The damage of the cell surfaces of the hepatocytes were also reduced as seen under a scanning electron microscope (SEM). Pretreatment with DDB (300 mg-kg-1) orally ameliorated the reduction of liver glycogen and blood glucose caused by ip injection of D-galactosamine (800 mg-kg-1) in mice. When normal rats were given DDB 300 mg-kg-1 once daily for 10 d, the free ribosomal protein and RNA in the liver increased significantly. These results indicate that DDB is of beneficial effects on both damaged and normal hepatocytes.
基金the Natural Science Fund of Jangsu Provinence (BK2004121) Trans-Century Training Programme Foundation for the Talents by the Chinese Ministry of Education
文摘Rare earth doped B2O3-Al2O3-SiO2 glass （RExBAS, x=5, 10, 20; RE=La, Sm） were prepared by solid state reaction method. Optical transmission spectra of such glass were characterized by ultraviolet spectrometers, and 1064 nm laser induced damage performance was investigated through the method of ＂1-on-1＂. The results indicated that there was a strong absorptive peak near 1064 nm in SmxBAS glass, the peak was enhanced with increasing x. While LaxBAS glass was transparent to 1064 nm laser, at the same time, the results of laser induced damage showed that the anti-laser induced damage performance of such glass was strengthened with the addition of rare earth oxide. Furthermore, the laser induced damage threshold （LIDT） of SmxBAS glass was significantly higher than that of LaxBAS glass. Consequently, Sm^3＋ doping was favor in the improvement of anti-laser induced damage performance for BAS glass.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11079012 and 11375037the National Basic Research Program of China under Grant No 2010CB832901
文摘The highly charged ion Ar^12＋ with an energy of 3 Me V is used for irradiating metallic glass （Cu47Zr45Al8）98.5Y1.5 and polycrystalline metallic W at the irradiation fluences of 1× 10^14 ions/cm2, 1 × 10^15 ions/cm^2 and 1 × 10^16 ions/cm^2. The main structure of metallic glass remains an amorphous phase under different irradiation fluences according to x-ray diffraction analysis. The scanning electron microscope observation on the morphologies indicates that no significant irradiation damage occurs on the surface and cross section of the metallic glass sample after different fluences of irradiation, while a large area of irregular cracks and holes were observed on the surface of metallic W at a fluence of 1 ×10^16 ions/cm^2, with cracks and channel impairments at a certain depth from the surface. The root-mean-square （rms） roughness of metallic glass increases with increasing fluence of Ar^12＋, while the reflectance decreases with increasing irradiation fluence. A nano-hardness test shows that the hardness of metallic glass decreases after irradiation. Under certain a higher capability of resistance to Ar^12＋ irradiation in conditions, metallic glass （Cu47 Zr45Al8 ）98.5 Y1.5 exhibits comparison with polycrystalline W.
基金Supported by the Ministry of Education and Science of Russia grants 6.4951.2017/6.7 and 6.6З24.2017/8.9
文摘Traumatic cerebral or spinal cord injury induced by military,traffic,and sports accidents,falls or environmental and anthropogenic catastrophes are among main causes of people mortality and disability,especially in young and middle age men（Kobeissy,2015）.Axon transection,or axotomy,occurs in wounds and during surgery.
文摘The present study was performed to determine the influence of lipid peroxidation and perturbance of Ca2+ homeostasis on liver damage induced by 2-chloro-1, 3-butadiene (CBD) and the protective effects of vitamin E in Wistar rats. Animals were given intraperitoneally different doses (8,40 or 200 mg·kg-1 daily) of CBD for 21 days, and the following dose-dependent events were observed: liver damage, significant increase in liver lipid peroxides, and decreases in activities of erythrocytic glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD). The pretreatment of rats with vitamin E (po 150 mg·kg-1) before administering CBD (iP 60 mg·kg-1 ) daily for 21 days prevented the following CBD-induced changes, the increase in serum cholylglycine (CG), hepatic LP, hepatic mitochondrion LP, hepatic oxidized glutathione (GSSG) (while the significant increase of reduced glutathione (GSH) was not affected) and the decrease in activities of erythrocytic SOD and hepatic mitochondrial calcium sequestration. These results suggest that lipid peroxidation and perturbance of Ca2+ homeostasis appear to contribute to the hepatotoxicity of CBD, and vitamin E might prevent the liver damage induced by CBD. The decrease in activities of GSH-Px and SOD in erythrocytes might be used as biomarkers for adverse effects of CBD on defense system against lipid peroxidation.
文摘Authors have conducted experiments to measure blast induced rock mass damage at L＆T-（Singoli-Bhatwari Hydro-Power Project SBHP） Rudraprayag. Repetitive NX size rock core up to 5.0 m depth were taken from side wall and face with triple tube core barrel drill. CR （core recovery） and RQD （rock quality designation） of the rock cores is computed to evaluate effect of blasting on the surrounding rock mass. RQD and CR values for the initial one meter from the line of excavation in each case reflect maximum damage due to blast. RQD for initial one meter reduced to as high as 40% of the average RQD. The rock samples were also tested using ultrasonic techniques. Ultrasonic tests on NX size core reveal that the 2.0 m of the zone surrounding the opening are adversely affected by the tunnel excavation blasting process. The ultrasonic velocities reduce to approx. 80% of the average values in the initial 0.5 m from the excavation line.
基金Project supported by the National Natural Science Foundation of China (Grant No.50875066)the National High Technology Research and Development Program of China (Grant No.2009AA044305)
文摘The KH2PO4 crystal is a key component in optical systems of inertial confinement fusion （ICF）. The microwaviness on a KH2PO4 crystal surface is strongly related to its damage threshold which is a key parameter for application. To study the laser induced damage mechanism caused by microwaviness, in this paper the near-field modulation properties of microwaviness to the incident wave are discussed by the Fourier modal method. Research results indicate that the microwaviness on the machined surface will distort the incident wave and thus lead to non-uniform distribution of the light intensity inside the crystal; in a common range of microwaviness amplitude, the light intensity modulation degree increases about 0.03 whenever the microwaviness amplitude increases 10 nm; 1 order diffraction efficiencies are the key factors responsible for light intensity modulation inside the crystal; the light intensity modulation is just around the microwaviness in the form of an evanescent wave, not inside the crystal when the microwaviness period is below 0.712μm; light intensity modulation degree has two extreme points in microwaviness periods of 1.064μm and 1.6μm, remains unchanged between periods of 3μm and 150μm, and descends above the period of 150μm to 920μm.
基金funded by DOE STTR grant No.DE-SC0019900in part funded by the UK EPSRC grants EP/G054950/1,EP/G056803/1,EP/G055165/1 and EP/M022463/1
文摘We present a fully three-dimensional kinetic framework for modeling intense short pulse lasers interacting with dielectric materials.Our work modifies the open-source particle-in-cell code EPOCH to include new models for photoionization and dielectric optical response.We use this framework to model the laser-induced damage of dielectric materials by fewcycle laser pulses.The framework is benchmarked against experimental results for bulk silica targets and then applied to model multi-layer dielectric mirrors with a sequence of simulations with varying laser fluence.This allows us to better understand the laser damage process by providing new insight into energy absorption,excited particle dynamics and nonthermal excited particle distributions.We compare common damage threshold metrics based on the energy density and excited electron density.
基金National Key Research and Development Program of China(2021YFB3601402)National Natural Science Foundation of China(61975153)。
文摘The laser-induced damage threshold(LIDT)of optical elements is a critical limitation in advancing nextgeneration spaceborne laser technologies.Transient mechanisms in multiple-pulse damage dynamics have been recognized,but significant gaps remain in understanding these processes.In this study,we introduce a practice time interval(Δt_(p))-dependent damage metric.Using a double-pulse double-probe experimental configuration,we systematically examine the double-pulse damage dynamics and relaxation process.The first pulse induces localized modifications that initiate a relaxation process,accumulating material damage caused by the subsequent pulse.Our results show that this relaxation lasts~500 ns for surface damage and is on a several millisecond scale for bulk damage.The second pulse induces more pronounced modifications and damage whenΔt_(p)is less than100 ns,dominated by nonlinear phenomena like multiphoton absorption due to temporally overlapping pulses.Conversely,forΔt_(p)>100 ns,thermal accumulation via phonon relaxation predominates.Additionally,the critical energy density for damage correlates positively with LIDT asΔt_(p)increases,reflecting the reduced thermal and mechanical stress influence.These findings highlight the dynamic competition between nonlinear and thermal effects in multiple-pulse laser interactions,providing practical strategies for designing optical components with high damage thresholds and developing high-performance optical systems.
文摘A comparison is made of several plasma-induced damage（PID） measurement techniques.A novel PID mechanism using high-density plasma（HDP） inter-metal dielectric（IMD） deposition is proposed.The results of a design of experiment（DOE） on Ar pre-clean minimizing PID are presented.For HDP oxide deposition,the plasma damage is minimal,assuring minimal exposure time of the metal line to the plasma using a maximal deposition to sputter ratio.This process induces less PID than classic SOG processing.Ar pre-clean induces minimal plasma damage using minimal process time,high ion energy and high plasma power.For metal etching,an HDP etch is compared to a reactive ion etch,and the impact of the individual process steps are identified by specialized antenna structures.The measurement results of charge pumping,breakdown voltage and gate oxide leakage correlate very well.On metal etching,the reactive ion etching induces less plasma damage than HDP etching.For both reactors, PID is induced only in the metal over-etch step.
文摘Leakage currents accelerate surface degradation of metal contacts via small scale arcing across lubricating films,but recent observations suggest that metallic nanoparticle additives in lubricants may be useful to improve contact performance.These findings prompted a study that examined electrically induced surface pitting of steel contacts in the presence of several lubricating greases including some containing nanometer-sized colloidal silver(Ag)particles.Reciprocating rolling sphere-on-disk experiments were conducted under electro-tribological loads employing polyurea greases derived from mineral and synthetic base oils with and without additives.Friction forces and electrical resistance were monitored continuously during the tests;surface changes were characterized by means of optical spectroscopy,stylus profilometry,and scanning electron microscopy(SEM)including compositional analysis using energy dispersive spectroscopy(EDS).The observations demonstrate that surface pitting induced by arcing occurs mainly at the points were the rolling motion changes direction and that eroded metal is deposited along the wear grove.Micron-sized pits are formed which contain carbon and oxygen indicating that arcing causes decomposition of the hydrocarbon lubricants.Numerous findings indicate a significant inhibition of pitting is induced by the Ag nanoparticles;some greases containing other additives exhibit a similar,although less pronounced,effect.
基金The Fundamental Research.Funds for Central.Public Welfare Research Institutes(Grant No.CKSF2023308/YT,CKSF2023316/YT,CKSF20241017/YT)National Natural Science Foundation of China(52109148,52279093).
文摘Blasting is widely used in hard rock tunnel excavation but often deteriorates the mechanical properties of the rock mass,forming a disturbance zone associated with energy evolution in the surrounding rock.In high-stress environments,this disturbance zone poses risks of engineering disasters like rock bursts.Previous studies confirm that optimizing the energy release process is an effective strategy for rock burst control.This research focuses on enhancing energy path optimization by analyzing parameters affecting the formation of the disturbance zone.Specifically,we conducted a sensitivity analysis of key blasting parameters,including caving hole spacing,caving blasting load,smooth blasting burden,hole spacing,and smooth blasting load.By exploring the impact of caving and smooth blasting under varied design conditions,we developed a method to control rock bursts through staged energy release,gradually disturbing the surrounding rock.Results indicate that aligning the disturbance zones induced by caving and smooth blasting can regulate the energy release process effectively,a staged and controlled energy release process is proposed to modulate the distribution and timing of strain energy dissipation,thereby reducing the risk of dynamic failure.This approach presents a novel method for managing rock burst tendencies in high-stress rock tunnel excavations.
文摘Radiotherapy is an effective local tumor ablation modality that can be used for the treatment of hepatocellular carcinoma(HCC)in specific clinical situations.Tumor cell ablation is facilitated through targeted ionizing radiation to directly induce DNA damage in cancer cells,which typically have dysfunctional DNA repair systems.In addition to direct tumor ablation,radiotherapy can also induce immunogenic cell death,release tumor-associated neoantigens,and promote dendritic cell activation.This type of immunogenic cell death can also significantly alter the tumor microenvironment,enhancing T-cell infiltration and reducing tumor-associated immune suppression.
文摘Objective To investigate the protective effect of Pglycoprotein up-regulated by ulinastatin(UTI)on HK-2cells during paraquat(PQ)-induced injury and its underlying mechanisms.Methods The research was divided into two parts.The first part of the research was divided into normal control group,PQ group,UTI+PQ group,UTI control group.The second part of the research was divided into negative virus group(including
基金supported by A (Research) Project Contract under NTG-CDU Partnership Agreement 2017-2024grateful for the financial support provided by the Northern Territory Government.
文摘To assess the long-term durability of waste-modified binder and asphalt mixtures as sustainable pavement solutions,their performance against the most dominant environmentally induced distresses in the extreme weather environments is studied.This is critical for utilization of such solutions since many roads can be subject to flood,high UV and extreme temperatures.This review focuses on crumb rubber modified binder(CRMB)and recycled plastic-modified binder(RPMB)to enhance their performance predictability and support their broader use in pavements.While the immediate benefits are well-documented,a focused review on the mechanisms of environmental degradation and their impact on performance is lacking.CRMB exhibits unique ageing mechanisms,displaying resistance to oxidative,thermal,and UV ageing,offering promise for enhancing asphalt durability in harsh environments.In contrast,when exposed to UV,RPMB tends to present a complex interplay of factors influenced by polymer type,dosage,and environmental conditions that variability would affect the reliability of the product and thus suggests the need for further research.Moisture-induced distress in CRMB and RPMB asphalt mixtures is also considered,highlighting the challenges and opportunities for improving moisture susceptibility of these binders.In the literature,chemical interaction between crumb rubber and binder enhances aggregate adhesion,while undissolved crumb rubber particles may hinder it;however,consensus is lacking on their collective impact alongside other mixture parameters on the moisture resistance of asphalt.Asphalt mixtures with recycled plastics have shown acceptable moisture resistance;however,further research is needed to understand the interplay between recycled plastic properties(polarity,melting point,chemical structure)and mixture characteristics(plastic content,mixing method,temperature)to enhance reliability.
