BACKGROUND The diagnosis of peripheral arteriopathy in the diabetic foot is complicated by diabetes and its advanced complications.It has been found that diabetic foot can be categorized into arterial stenosis and non...BACKGROUND The diagnosis of peripheral arteriopathy in the diabetic foot is complicated by diabetes and its advanced complications.It has been found that diabetic foot can be categorized into arterial stenosis and non-arterial stenosis,both of which have significant differences in hemodynamic characteristics.AIM To evaluate the early hemodynamic changes in diabetic foot patients with nonarterial stenosis and arterial stenosis treated by tibial transverse transport(TTT)using high-frequency color Doppler ultrasonography(HFCDU)and a laser Doppler flowmeter.METHODS Twenty-five patients with Wagner grades 3-5 diabetic foot ulcers were treated with TTT,and the wound healing time and rate were recorded.Patients were grouped according to the results of preoperative lower-extremity ultrasonography.Cases with≥50%stenosis in any of the femoral,popliteal,posterior tibial,anterior tibial,and peroneal arteries of the affected limb were classified as the arterial stenosis group(n=16);otherwise,they were classified as the nonarterial stenosis group(n=9).Before and one month after surgery,HFCDU was used to evaluate the degree of lower limb artery lesions and hemodynamic changes in patients.The degree of femoral-popliteal atherosclerotic stenosis,the degree of vascular stenosis and occlusion of the lower-knee outflow tract,and the degree of medial arterial calcification were scored;the three scores were added together to obtain the total score of lower extremity arteriopathy.PeriScanPIM3,a laser Doppler flowmeter system,was used to detect alterations in plantar microcirculation before and 1 mo after surgery.Wound healing and hemodynamic indices were compared between the two groups.RESULTS The wound healing time of the diabetic foot was significantly shorter in the nonarterial stenosis group than in the arterial stenosis group(47.8±13 vs 85.8±26,P<0.05),and the wound healing rate of both groups was 100%.The preoperative total lower extremity arteriopathy scores were lower in the nonarterial stenosis group than those in the arterial stenosis group(18.89±8.87 vs 24.63±3.52,P<0.05).The nonarterial stenosis group showed higher preoperative popliteal artery(POA)blood flow than the arterial stenosis group(204.89±80.76 cc/min vs 76.75±48.49 cc/min,P<0.05).Compared with the baseline(before surgery),the postoperative POA blood flow of the affected limb in the nonarterial stenosis group decreased one month after surgery(134.11±47.84 cc/min vs 204.89±80.76 cc/min,P<0.05),while that in the arterial stenosis group increased(98.44±30.73 cc/min vs 61.69±21.70 cc/min,P<0.05).Although the POA blood flow in the arterial stenosis group was obviously improved one month after surgery,it was still lower than that in the nonarterial stenosis group(98.44±30.73 cc/min vs 134.11±47.84 cc/min,P<0.05).The nonarterial stenosis group had higher preoperative plantar microcirculation than the arterial stenosis group(56.1±9.2 vs 33.2±7.5,P<0.05);compared with the baseline,the plantar microcirculation in the arterial stenosis group was significantly improved one month after surgery(51.9±7.2,P<0.05),while that in the nonarterial stenosis group was reduced(35.9±7.2,P<0.05).CONCLUSION Based on preoperative HFCDU findings,diabetic foot patients can be divided into two categories:Those with nonarterial stenosis and those with arterial stenosis,with obvious differences in hemodynamic changes in the early postoperative period between them.In the early stage after TTT,the blood flow volume and velocity and the plantar microcirculation perfusion of the affected limb of the diabetic foot with nonarterial stenosis decreased compared with the baseline,while those of the diabetic foot with arterial stenosis improved significantly compared with the baseline,although both had smoothly healed diabetic foot ulcers.展开更多
BACKGROUND： At present, inhalation of nitrogen monoxidum （NO） or other angiotenic is widely used to cure hypoxic pulmonary artery hypertension. In addition, recent researches demonstrate that postganglionic fiber o...BACKGROUND： At present, inhalation of nitrogen monoxidum （NO） or other angiotenic is widely used to cure hypoxic pulmonary artery hypertension. In addition, recent researches demonstrate that postganglionic fiber of stellate ganglion can regulate contents of blood vessel endothelium-calcitonin gene-related peptide （BVE-CGRP） and nitricoxide synthase （NOS） in lung tissue. Therefore, stellate ganglion which is blocked with the local anesthetic may cause therapeutic effects on hypoxic pulmonary artery hypertension. OBJECTIVE： To observe the effects of stellate block on calcitonin gene-related peptide （CGRP） of vasodilation factors, prostacyclin, endothelin-i of vasoconstriction factors, thromboxan, blood vessel endothelium-nitricoxide synthase （BVE-NOS） and mean arterial pressure of lung tissue in rabbits with hypoxic pulmonary artery hypertension. DESIGN： Randomly controlled animal study. SETTING： Neurological Institute of Taihe Hospital Affiliated to Yunyang Medical College. MATERIALS： A total of 24 adult Japanese rabbits of both genders and weighing 2.3 - 2.6 kg were provided by Animal Experimental Center of Hubei Academy of Medical Science. SP kit was provided by Beijing Zhongshan Biotechnology Co., Ltd.; moreover, kits of endothelin-1, CGRP, prostacyclin and thromboxan were provided by Radioimmunity Institute, Scientific and Technological Developing Center, General Hospital of Chinese PLA, and color image analytical system （Leica-Q500IW） was made in Germany. METHODS：The experiment was carried out in the Neurological Institute of Taihe Hospital affiliated to Yunyang Medical College from February to December 2002. ① Rabbits were performed with aseptic manipulation to exposure left stellate ganglion and then it was put in epidural catheter for 1 week. In addition, one end of epidural catheter was fixed near by stellate ganglion and the other end was fixed through dorsal neck. All rabbits were randomly divided into 4 groups, including normal control group, stellate block group, hypoxia group and hypoxia ＋ stellate block group, with 6 in each group. Rabbits in the normal control group were perfused with saline through epidural catheter with 0.5 mL once for three times per day and 3 successive days in total; in addition, rabbits in the stellate block group were perfused with 2.5 g/L bupivacaine through epidural catheter with 0.5 mL once for three times per day and 3 successive days in total. Rabbits in the hypoxia group were used to establish hypoxic pulmonary artery hypertension models. That was to say, the experimental rabbits were put in hypoxic box （containing sodalime and calcium chloride to absorb CO2 and water） and given various flows of oxygen and nitrogen through the two lateral wells simultaneously. And then, oxygen was monitored with oxygen-concentration monitoring device to control the concentration in （10±2）% for 8 hours per day and 2 successive weeks in total. Rabbits in the hypoxia ＋ stellate block group were used to establish hypoxia models as the same as those in the hypoxia group. Two weeks later, 2.5 g,/L bupivacaine was pushed into epidural catheter with 0.5 mL once for three times per day and 3 successive days in total. Breast was directly opened to measure mean pulmonary artery pressure.② 6 mL blood was collected through pulmonary arterial duct to measure levels of plasma CGRP, prostacyclin, endothelin-I and thromboxane with radio-immunity technique; meanwhile, immunohistochemical staining was used to observe the changes of BVE-NOS content of the experimental rabbits in all groups. MAIN OUTCOME MEASURES： Changes of CGRP, prostacyclin, endothelin-1 and thromboxane and BVE-NOS. RESULTS： A total of 24 experimental rabbits were involved in the final analysis. ①As compared with those in the normal control group, hypoxic pulmonary artery hypertension of the experimental rabbits was higher in the hypoxia group and hypoxia ＋ stellate block group after hypoxia [（3.8±0.30）, （3.16±0.45）, （2.60± 0.27） kPa, P 〈 0.05, 0.01]; CGRP was lower [（68.20 ±8.78）, （108.24 ±14.35）, （130.25 ±22.70） ng/L, P 〈 0.05, 0.01]; prostacyclin was lower [（94.45± 10.68）, （98.77± 12.31）, （155.27±20.67） ng/L, P 〈 0.01]; endothelin-1 was higher [（184.7±29.66）, （115.27± 13.62）, （98.20±11.52）, ng/L, P 〈 0.05, 0.01]; thromboxan was higher [（226.27 ±30.46）, （207.67 ±27.32）, （124.25 ± 16.89） ng/L, P 〈 0.01 ]. As compared with that in hypoxia group, hypoxic pulmonary artery hypertension was decreased in hypoxia ＋ stellate block group （P 〈 0.05）, CGRP was increased （P 〈 0.01）, and endothelin-1 was decreased remarkably （P 〈 0.05）. ② Level of BVE-NOS of the experimental rabbits was higher in stellate block group, hypoxia group and hypoxia ＋ stellate block group than that in the normal control group [（0.25±0.06）, （0.27±0.07）, （0.46± 0.12）, （0.14±0.03）, P 〈 0.05], and NOS level was higher in the hypoxia ＋ stellate block group than that in hypoxia group （P 〈 0.05）. CONCLUSION： Mean arterial pressure is decreased in rabbits with hypoxic pulmonary artery hypertension after stellate block and level of endothelin-1 is also decreased; however, levels of CGRP and NOS are increased respectively.展开更多
Stimulation of unconsolidated formations via horizontal wells has seen its vast implementation in the recent development of heavy oil reservoir to save the time and cost of preheating the reservoir before the steam-as...Stimulation of unconsolidated formations via horizontal wells has seen its vast implementation in the recent development of heavy oil reservoir to save the time and cost of preheating the reservoir before the steam-assisted gravity drainage(SAGD)process.A mathematical approach was proposed in this research that fully couples the hydraulic,mechanical and thermal responses of unconsolidated sandstone formations and also applies failure criteria for describing either shear dilation or tensile parting mechanism that generates microcracks.The approach was implemented to predict the porothermoelastic response of a pair of SAGD wells subject to injection and subsequent micro-fracturing using hot water.It was found that the predicted bottom hole pressures(BHPs)match closely with the field observed data.An elliptical dilation zone developed around the dual wells with relatively high pore pressure,porosity,permeability and temperature,implying good interwell hydraulic communication between both wells.The activation of microcracks dramatically accelerated the dissipation of pore pressure across the entire formation depth and also facilitated heat convection in between the dual wells,though to a lesser extent.In summary,the approach provides a convenient means to assist field engineers in the optimization of injection efficiency and evaluation of interference among multiple horizontal wells.展开更多
BACKGROUND Complex hypospadias is a surgical challenge.AIM To present the long-term outcomes of two-stage repair of complex hypospadias using a scrotal septal flap.METHODS This was a retrospective study of patients wi...BACKGROUND Complex hypospadias is a surgical challenge.AIM To present the long-term outcomes of two-stage repair of complex hypospadias using a scrotal septal flap.METHODS This was a retrospective study of patients with complex hypospadias who were operated on between January 1st,2001,and January 1st,2019,at a single hospital using a scrotal septal flap(two-stage surgery)or prepuce flap(one-stage surgery;control group).In the scrotal group,the urethra was first repaired using oral mucosa;in the second stage,a scrotal septal flap was used as a second impermeable layer.Maximal/average urinary flow rates after surgery were compared.All patients were followed for≥6 mo(range:6-96 mo).RESULTS Ninety-seven patients were included(46 in the scrotal group and 51 in the prepuce group).The maximal urinary flow rate was 15.4±2.1 mL/s in the scrotal group and 14.3±3.0 mL/s in the control group(P=0.035).The average urinary flow rate was 8.4±2.3 mL/s in the scrotal group and 7.5±1.5 mL/s in the control group(P=0.019).The proportion of patients achieving good therapeutic effects was higher in the scrotal group than in the control group[24(52.2%)vs 16(31.4%),P=0.042;34(73.9%)vs 25(49.0%),P=0.014].The scrotal flap two-stage surgery was independently associated with a higher maximal urinary flow rate(OR=2.416,95%CI:1.026-5.689,P=0.044)and with a higher average flow rate(OR=2.484,95%CI:1.054-5.854,P=0.038).CONCLUSION In complex hypospadias,a scrotal septal flap could be a versatile and reliable option for resurfacing the penis.展开更多
Increasing the phonon scattering center by adding nanoparticles to thermoelectric materials is an effective method of regulating the thermal conductivity.In this study,a series of Ca3 Co_(4)O_(9)/x wt.%CNTs(x=0,3,5,7,...Increasing the phonon scattering center by adding nanoparticles to thermoelectric materials is an effective method of regulating the thermal conductivity.In this study,a series of Ca3 Co_(4)O_(9)/x wt.%CNTs(x=0,3,5,7,10)polycrystalline ceramic thermoelectric materials by adding carbon nanotubes(CNTs)were prepared with sol-gel method and cold-pressing sintering technology.The results of x-ray diffraction and field emission scanning electron microscopy show that the materials have a single-phase structure with high orientation and sheet like microstructure.The effect of adding carbon nanotubes to the thermoelectric properties of Ca_(3)Co_(4)O_(9)was systematically measured.The test results of thermoelectric properties show that the addition of carbon nanotubes reduces the electrical conductivity and Seebeck coefficient of the material.Nevertheless,the thermal conductivity of the samples with carbon nanotubes addition is lower than that of the samples without carbon nanotubes.At 625 K,the thermal conductivity of Ca3 Co_(4)O_(9)/10 wt.%CNTs sample is reduced to0.408 W·m^(-1)·K^(-1),which is about 73%lower than that of the original sample.When the three parameters are coupled,the figure of merit of Ca_(3)Co_(4)O_(9)/3 wt.%CNTs sample reaches 0.052,which is 29%higher than that of the original sample.This shows that an appropriate amount of carbon nanotubes addition can reduce the thermal conductivity of Ca_(3)Co_(4)O_(9)ceramic samples and improve their thermoelectric properties.展开更多
In this study,the dynamic compressive response behavior of a body-centered cubic(BCC)single-phase TiZrNbV refractory high-entropy alloy(RHEA)was investigated under impact at speeds of 313-1584 m s^(-1)using two-stage,...In this study,the dynamic compressive response behavior of a body-centered cubic(BCC)single-phase TiZrNbV refractory high-entropy alloy(RHEA)was investigated under impact at speeds of 313-1584 m s^(-1)using two-stage,gas-gun-driven,high-speed plate-impact experiments;recovery sample analysis;and theoretical calculations.The strain rate and pressure were approximately 10^(7) s^(−1) and 5.07-29.37 GPa,respectively.The results showed that the TiZrNbV RHEA had a Hugoniot elastic limit of 4.12-5.86 GPa and a spall strength of 1.84-2.03 GPa.The initial yield strength of the alloy showed a strong strain-rate dependence and could be described by the modified Zerilli-Armstrong model,while the phonon-damping effect was the main reason for its high strain-rate sensitivity.Microstructural analysis showed that the dynamic deformation of the TiZrNbV RHEA was controlled by the dislocation slip,dislocation proliferation,intersection of the deformation bands,and grain refinement.The analysis also showed that the intergranular,transgranular,and mixed-type cracks dominated the spall failure of the material.The dynamic Hall-Petch effect and pinning from the lattice distortion led to high dynamic yield strength.The critical strain rate for the phonon drag effect was positively related to the relative atomic mass and local strain field of the metals.Within the experimental loading range,the RHEA showed good structural stability,and simultaneously,the theoretical calculation method for the equation of state based on a cold-energy mixture could accurately predict its shock-response behavior.The valence-electron concentration(VEC)had a direct effect on the shock-compression properties of the HEAs;higher VEC implied more difficulty in compressing the HEAs.The findings of this study provide insights into understanding the mechanical response characteristics of RHEAs under extreme conditions such as high-speed impact and ultrahigh strain-rate loading.展开更多
Activity hijacking is one of the most powerful attacks in Android. Though promising, all the prior activity hijacking attacks suffer from some limitations and have limited attack capabilities. They no longer pose secu...Activity hijacking is one of the most powerful attacks in Android. Though promising, all the prior activity hijacking attacks suffer from some limitations and have limited attack capabilities. They no longer pose security threats in recent Android due to the presence of effective defense mechanisms. In this work, we propose the first automated and adaptive activity hijacking attack, named VenomAttack, enabling a spectrum of customized attacks (e.g., phishing, spoofing, and DoS) on a large scale in recent Android, even the state-of-the-art defense mechanisms are deployed. Specifically, we propose to use hotpatch techniques to identify vulnerable devices and update attack payload without re-installation and re-distribution, hence bypassing offline detection. We present a newly-discovered flaw in Android and a bug in derivatives of Android, each of which allows us to check if a target app is running in the background or not, by which we can determine the right attack timing via a designed transparent activity. We also propose an automated fake activity generation approach, allowing large-scale attacks. Requiring only the common permission INTERNET, we can hijack activities at the right timing without destroying the GUI integrity of the foreground app. We conduct proof-of-concept attacks, showing that VenomAttack poses severe security risks on recent Android versions. The user study demonstrates the effectiveness of VenomAttack in real-world scenarios, achieving a high success rate (95%) without users’ awareness. That would call more attention to the stakeholders like Google.展开更多
A 12-wk trial was conducted to compare the tolerance of tilapia to high carbohydrate and high lipid diets.Three isonitrogenous and isoenergetic diets,whose carbohydrate and lipid levels were the following:35.0%and 8%(...A 12-wk trial was conducted to compare the tolerance of tilapia to high carbohydrate and high lipid diets.Three isonitrogenous and isoenergetic diets,whose carbohydrate and lipid levels were the following:35.0%and 8%(control),44.2%and 4%(D1,high carbohydrate),and 25.8%and 12%(D2,high lipid),respectively.Three hundred tilapias(27±0.11 g)were fed the diets for 10 wk(4 replicates per group);72 fish from the D1 group were continually fed the D1(D1D1)and 72 fish from the D2 were continually fed the D2(D2D2)diet for 2 wk(3 replicates each group)to evaluate the tilapia's capacity to tolerate high carbohydrate and high lipid diets,respectively.Another 36 fish from D1 group were continually fed D2(D1D2)for comparison with D1D1 and D2D2 groups.In phase 1,hepatosomatic index,liver triglycerides(TG),glucose tolerance(GT)and crude protein in the whole body in D1 group were higher than those in D2 group(P<0.05).During phase 2,D1D1 group had lower feed intake and weight gain,as well as lower serum total protein and albumin than that of D2D2 group(P<0.05),while its liver glycogen was significantly higher than that in D1D2 and D2D2 groups(P<0.05).Moreover,serum glucose and GT were higher in D1D1 and D1D2 groups than those in D2D2 group(P<0.05).By contrast,D2D2 group had significantly higher intraperitoneal fat,subcutaneous adipose tissue(SCAT)and liver TG than those in D1D1 group(P<0.05).The mRNA expression of brain npy,hepatic nrf2,gst1 and hepatic transcriptomic data showed that immune-related genes(gama,mrc2,mhc2 and cd163),were downregulated in D1D1 group compared to D2D2 and D1D2 groups.Taken together:1)tilapia have higher tolerance to a high lipid diet than high carbohydrate diet;2)despite retention of glucose tolerance,the continuous feeding of D1 diet impaired tilapia's appetite,weight gain rate and host immune response;3)specific distri-bution of fat in intraperitoneal regions,SCAT and liver may be a risk-avoidance strategy in tilapia in response to a continuous D2 diet.展开更多
Hydrocephalus is often treated with a cerebrospinal fluid shunt(CFS) for excessive amounts of cerebrospinal fluid in the brain.However,it is very difficult to distinguish whether the ventricular enlargement is due to ...Hydrocephalus is often treated with a cerebrospinal fluid shunt(CFS) for excessive amounts of cerebrospinal fluid in the brain.However,it is very difficult to distinguish whether the ventricular enlargement is due to hydrocephalus or other causes,such as brain atrophy after brain damage and surgery.The non-trivial evaluation of the consciousness level,along with a continuous drainage test of the lumbar cistern is thus clinically important before the decision for CFS is made.We studied 32 secondary mild hydrocephalus patients with different consciousness levels,who received T1 and diffusion tensor imaging magnetic resonance scans before and after lumbar cerebrospinal fluid drainage.We applied a novel machine-learning method to find the most discriminative features from the multi-modal neuroimages.Then,we built a regression model to regress the JFK Coma Recovery Scale-Revised(CRS-R) scores to quantify the level of consciousness.The experimental results showed that our method not only approximated the CRS-R scores but also tracked the temporal changes in individual patients.The regression model has high potential for the evaluation of consciousness in clinical practice.展开更多
Ga-based liquid metal has drawn attention in the field of interface science due to its large deformability.However, the spreading and shaping of liquid metal still remain a huge challenge to be solved owing to its lar...Ga-based liquid metal has drawn attention in the field of interface science due to its large deformability.However, the spreading and shaping of liquid metal still remain a huge challenge to be solved owing to its large surface tension.Here, an intriguing synergistic oxidation-driven liquid metal fractal phenomenon was discovered and the general mechanisms were interpreted, which provides a new strategy for manipulating liquid metal.Experimental results demonstrate that the liquid metal placed on the graphite plate exhibited fractal characteristics with the addition of hydrogen peroxide.Here, it is of significance that hydrogen peroxide and graphite plates synergistically oxidize liquid metal.In addition, we predicted that liquid metal fractals can also be achieved on other eligible substrates based on the proposed general mechanism, which was confirmed by relevant experiments.Furthermore, the fractal dimensions of liquid metal fractal pattern were obtained and evaluated, distinguishing the synergistic oxidation-driven liquid metal fractals from the voltage-driven liquid metal fractals.Besides, we initially gave the best concentration range in which dendritic fractals can occur in order to guide practice.The ability to achieve liquid metal fractals promises rich opportunities in freely driving the liquid metal for soft machines and manufacturing the shape-reconfigurable electronic circuits.展开更多
The hydrodynamic characteristics of hybrid fluid made of liquid metal/aqueous solution are elementary in the design and operation of conductive flow in a variety of newly emerging areas such as chip cooling, soft robo...The hydrodynamic characteristics of hybrid fluid made of liquid metal/aqueous solution are elementary in the design and operation of conductive flow in a variety of newly emerging areas such as chip cooling, soft robot, and biomedical practices. chemical properties, such as In terms of physical and density, thermal conductivity and electrical conductivity, their huge differences between the two fluidic phases remain a big challenge for analyzing the hybrid flow behaviors. Besides, the liquid metal immersed in the solution can move and deform when administrated with non-contact electromagnetic force, or even induced by redox reaction, which is entirely different from the cases of conventional contact force. Owing to its remarkable capability in flow and deformation, liquid metal immersed in the solution is apt to deform on an extremely large scale, resulting in marked changes on its boundary and interface. However, the working mechanisms of the movement and deformation of liquid metal lack appropriate models to describe such scientific issues via a set of well-established unified equations. To promote investigations in this important area, the present paper is dedicated to summarizing this unconventional hydrodynamics from experiment, theory, and simulation. Typical experimental phenomena and basic working mechanisms are illustrated, followed by the movement and deformation theories to explain these phenomena. Several representative simulation methods are then proposed to tackle the governing functions of the electrohydrodynamics. Finally, prospects and challenges are raised, offering an insight into the new physics of the hybrid fluid under applied fields.展开更多
Recent years have witnessed a rapid development of deformable devices and epidermal electronics that are in urgent request for flexible batteries.The intrinsically soft and ductile conductive electrode materials can o...Recent years have witnessed a rapid development of deformable devices and epidermal electronics that are in urgent request for flexible batteries.The intrinsically soft and ductile conductive electrode materials can offer pivotal hints in extending the lifespan of devices under frequent deformation.Featuring inherent liquidity,metal-licity,and biocompatibility,Ga-based room-temperature liquid metals(GBRTLMs)are potential candidates to fulfill the requirement of soft batteries.Herein,to illustrate the glamour of liquid components,high-temperature liquid metal batteries(HTLMBs)are briefly summarized from the aspects of principle,application,advantages,and drawbacks.Then,Ga-based liquid metals as main working electrodes in primary and secondary batteries are reviewed in terms of battery configurations,working mechanisms,and fiinctions.Next,Ga-based liquid metals as auxiliary working electrodes in lithium and nonlithium batteries are also discussed,which work as functional self-healing additives to alleviate the degradation and enhance the durability and capacity of the battery system.After that,Ga-based liquid metals as interconnecting electrodes in multi-scenarios including photovoltaics solar cells,generators,and supercapacitors(SCs)are interpreted,respectively.The summary and perspective of Ga-based liquid metals as diverse battery materials are also focused on.Finally,it was suggested that tremendous endeavors are yet to be made in exploring the innovative battery chemistry,inherent reaction mechanism,and multifunctional integration of Ga-based liquid metal battery systems in the coining future.展开更多
Using scanning, transmission electron microscopy and aberration-corrected scanning transmission electron microscopy, we have studied the interactions between dislocations and twins in impact deformed polysynthetic twi...Using scanning, transmission electron microscopy and aberration-corrected scanning transmission electron microscopy, we have studied the interactions between dislocations and twins in impact deformed polysynthetic twinned TiAl crystal. The 1/3 < 111] and 1/6 < 211] step dislocations on coherent twin boundaries reveal the interactions of glissile 1/2 < 101> dislocations with the coherent twin boundaries.An abnormal stacking fault was found adjacent to the coherent twin boundary. It has the same stacking sequence but different atom species in the [110] direction with an additional displacement of 1/4[110]in two neighboring {111} layers, and is likely induced by the slip of a 1/12[112](i.e. 1/4[110] + 1/6[211])dislocation.展开更多
Liquid metal(LM)is a type of metal or alloy that has a low melting point near room temperature and exhibits the properties of both liquids and metals.Such unconventional materials have been gaining increasing attentio...Liquid metal(LM)is a type of metal or alloy that has a low melting point near room temperature and exhibits the properties of both liquids and metals.Such unconventional materials have been gaining increasing attention within the scientific and industrial communities.Recently,fiber-shaped LM and its composites have especially attracted diverse interest owing to their unique merits,such as excellent conductivity,intrinsic stretchability,facile phase transition,and the ability to be woven or knitted into smart fabrics.This review is dedicated to summarizing different aspects of LM-based fibers,such as their material components,fabrication and design strategies,and remarkable applications by way of their representative properties.Typical fabrication approaches,such as 3D printing of pure LM wire,coating the LM shell on the surface of the fiber,injecting a LM core into hollow fibers,and spinning of LM and polymer hybrids have been comparatively illustrated.Moreover,emerging applications that primarily utilize LM fibers have been demonstrated.Finally,future directions and opportunities in the field are discussed.This categorization of LM fibers is expected to facilitate further investigation and practice in the coming society.展开更多
The paper presents a novel control design,which is based on the idea of active disturbance rejection control(ADRC),for a kind of flexible aerocraft whose contolled variable cannot be measured directly.Since the origin...The paper presents a novel control design,which is based on the idea of active disturbance rejection control(ADRC),for a kind of flexible aerocraft whose contolled variable cannot be measured directly.Since the original frame of ADRC can-not be directly applied,the paper puts forward a new extended state observer(ESO)and the corresponding ADRC law.In order to assign the poles of the closed loop system to ideal positions such that the vibration can be quickly suppressed,an elastic damping term is added into feedback law.The advantages of the new ESO for fectively estimating both the rigid mode and elastic mode from the measurements are discussed.Moreover,the analysis on the stabiliy.the relative stability and the steady state of the closed-loop system is given.Finally,the efectiveness and robustness of the proposed ADRC are verified by simulations.展开更多
A Ta wire-reinforced Zr-based bulk metallic glass composite with a new type of structure was prepared successfully by the method of liquid metal infiltration. Ta wires distribute uniformly in the metallic glass matrix...A Ta wire-reinforced Zr-based bulk metallic glass composite with a new type of structure was prepared successfully by the method of liquid metal infiltration. Ta wires distribute uniformly in the metallic glass matrix in the form of spirals. The composite exhibits two yield stages under compressive stress, and the samples are compressed into thin pancakes. The micro-cracks originate at the interface between the Ta wire and the metallic glass matrix and propagate perpendicularly to the interface, which then induce multiple shear bands in the metallic glass matrix due to the stress concentration. Shear cracks form in the metallic glass matrix during the continued loading process as a result of the interaction of shear bands. Deformation bands of Ta wires occur under the impact of shear bands. The local stress fields in the composite are changed obviously due to the introduction of the spiral-formed reinforcements. The investigation of the deformation behavior and mechanism suggests a new method for the application of bulk metallic glass composites as the structural materials.展开更多
基金the General Project of Hubei Provincial Department of Health,No.WJ2021M139.the People's Hospital of Wuhan University(Approval No.WDRY2022-K200).
文摘BACKGROUND The diagnosis of peripheral arteriopathy in the diabetic foot is complicated by diabetes and its advanced complications.It has been found that diabetic foot can be categorized into arterial stenosis and non-arterial stenosis,both of which have significant differences in hemodynamic characteristics.AIM To evaluate the early hemodynamic changes in diabetic foot patients with nonarterial stenosis and arterial stenosis treated by tibial transverse transport(TTT)using high-frequency color Doppler ultrasonography(HFCDU)and a laser Doppler flowmeter.METHODS Twenty-five patients with Wagner grades 3-5 diabetic foot ulcers were treated with TTT,and the wound healing time and rate were recorded.Patients were grouped according to the results of preoperative lower-extremity ultrasonography.Cases with≥50%stenosis in any of the femoral,popliteal,posterior tibial,anterior tibial,and peroneal arteries of the affected limb were classified as the arterial stenosis group(n=16);otherwise,they were classified as the nonarterial stenosis group(n=9).Before and one month after surgery,HFCDU was used to evaluate the degree of lower limb artery lesions and hemodynamic changes in patients.The degree of femoral-popliteal atherosclerotic stenosis,the degree of vascular stenosis and occlusion of the lower-knee outflow tract,and the degree of medial arterial calcification were scored;the three scores were added together to obtain the total score of lower extremity arteriopathy.PeriScanPIM3,a laser Doppler flowmeter system,was used to detect alterations in plantar microcirculation before and 1 mo after surgery.Wound healing and hemodynamic indices were compared between the two groups.RESULTS The wound healing time of the diabetic foot was significantly shorter in the nonarterial stenosis group than in the arterial stenosis group(47.8±13 vs 85.8±26,P<0.05),and the wound healing rate of both groups was 100%.The preoperative total lower extremity arteriopathy scores were lower in the nonarterial stenosis group than those in the arterial stenosis group(18.89±8.87 vs 24.63±3.52,P<0.05).The nonarterial stenosis group showed higher preoperative popliteal artery(POA)blood flow than the arterial stenosis group(204.89±80.76 cc/min vs 76.75±48.49 cc/min,P<0.05).Compared with the baseline(before surgery),the postoperative POA blood flow of the affected limb in the nonarterial stenosis group decreased one month after surgery(134.11±47.84 cc/min vs 204.89±80.76 cc/min,P<0.05),while that in the arterial stenosis group increased(98.44±30.73 cc/min vs 61.69±21.70 cc/min,P<0.05).Although the POA blood flow in the arterial stenosis group was obviously improved one month after surgery,it was still lower than that in the nonarterial stenosis group(98.44±30.73 cc/min vs 134.11±47.84 cc/min,P<0.05).The nonarterial stenosis group had higher preoperative plantar microcirculation than the arterial stenosis group(56.1±9.2 vs 33.2±7.5,P<0.05);compared with the baseline,the plantar microcirculation in the arterial stenosis group was significantly improved one month after surgery(51.9±7.2,P<0.05),while that in the nonarterial stenosis group was reduced(35.9±7.2,P<0.05).CONCLUSION Based on preoperative HFCDU findings,diabetic foot patients can be divided into two categories:Those with nonarterial stenosis and those with arterial stenosis,with obvious differences in hemodynamic changes in the early postoperative period between them.In the early stage after TTT,the blood flow volume and velocity and the plantar microcirculation perfusion of the affected limb of the diabetic foot with nonarterial stenosis decreased compared with the baseline,while those of the diabetic foot with arterial stenosis improved significantly compared with the baseline,although both had smoothly healed diabetic foot ulcers.
基金the Key Technology Development Foundation of Hubei Province, No. 20002B33
文摘BACKGROUND： At present, inhalation of nitrogen monoxidum （NO） or other angiotenic is widely used to cure hypoxic pulmonary artery hypertension. In addition, recent researches demonstrate that postganglionic fiber of stellate ganglion can regulate contents of blood vessel endothelium-calcitonin gene-related peptide （BVE-CGRP） and nitricoxide synthase （NOS） in lung tissue. Therefore, stellate ganglion which is blocked with the local anesthetic may cause therapeutic effects on hypoxic pulmonary artery hypertension. OBJECTIVE： To observe the effects of stellate block on calcitonin gene-related peptide （CGRP） of vasodilation factors, prostacyclin, endothelin-i of vasoconstriction factors, thromboxan, blood vessel endothelium-nitricoxide synthase （BVE-NOS） and mean arterial pressure of lung tissue in rabbits with hypoxic pulmonary artery hypertension. DESIGN： Randomly controlled animal study. SETTING： Neurological Institute of Taihe Hospital Affiliated to Yunyang Medical College. MATERIALS： A total of 24 adult Japanese rabbits of both genders and weighing 2.3 - 2.6 kg were provided by Animal Experimental Center of Hubei Academy of Medical Science. SP kit was provided by Beijing Zhongshan Biotechnology Co., Ltd.; moreover, kits of endothelin-1, CGRP, prostacyclin and thromboxan were provided by Radioimmunity Institute, Scientific and Technological Developing Center, General Hospital of Chinese PLA, and color image analytical system （Leica-Q500IW） was made in Germany. METHODS：The experiment was carried out in the Neurological Institute of Taihe Hospital affiliated to Yunyang Medical College from February to December 2002. ① Rabbits were performed with aseptic manipulation to exposure left stellate ganglion and then it was put in epidural catheter for 1 week. In addition, one end of epidural catheter was fixed near by stellate ganglion and the other end was fixed through dorsal neck. All rabbits were randomly divided into 4 groups, including normal control group, stellate block group, hypoxia group and hypoxia ＋ stellate block group, with 6 in each group. Rabbits in the normal control group were perfused with saline through epidural catheter with 0.5 mL once for three times per day and 3 successive days in total; in addition, rabbits in the stellate block group were perfused with 2.5 g/L bupivacaine through epidural catheter with 0.5 mL once for three times per day and 3 successive days in total. Rabbits in the hypoxia group were used to establish hypoxic pulmonary artery hypertension models. That was to say, the experimental rabbits were put in hypoxic box （containing sodalime and calcium chloride to absorb CO2 and water） and given various flows of oxygen and nitrogen through the two lateral wells simultaneously. And then, oxygen was monitored with oxygen-concentration monitoring device to control the concentration in （10±2）% for 8 hours per day and 2 successive weeks in total. Rabbits in the hypoxia ＋ stellate block group were used to establish hypoxia models as the same as those in the hypoxia group. Two weeks later, 2.5 g,/L bupivacaine was pushed into epidural catheter with 0.5 mL once for three times per day and 3 successive days in total. Breast was directly opened to measure mean pulmonary artery pressure.② 6 mL blood was collected through pulmonary arterial duct to measure levels of plasma CGRP, prostacyclin, endothelin-I and thromboxane with radio-immunity technique; meanwhile, immunohistochemical staining was used to observe the changes of BVE-NOS content of the experimental rabbits in all groups. MAIN OUTCOME MEASURES： Changes of CGRP, prostacyclin, endothelin-1 and thromboxane and BVE-NOS. RESULTS： A total of 24 experimental rabbits were involved in the final analysis. ①As compared with those in the normal control group, hypoxic pulmonary artery hypertension of the experimental rabbits was higher in the hypoxia group and hypoxia ＋ stellate block group after hypoxia [（3.8±0.30）, （3.16±0.45）, （2.60± 0.27） kPa, P 〈 0.05, 0.01]; CGRP was lower [（68.20 ±8.78）, （108.24 ±14.35）, （130.25 ±22.70） ng/L, P 〈 0.05, 0.01]; prostacyclin was lower [（94.45± 10.68）, （98.77± 12.31）, （155.27±20.67） ng/L, P 〈 0.01]; endothelin-1 was higher [（184.7±29.66）, （115.27± 13.62）, （98.20±11.52）, ng/L, P 〈 0.05, 0.01]; thromboxan was higher [（226.27 ±30.46）, （207.67 ±27.32）, （124.25 ± 16.89） ng/L, P 〈 0.01 ]. As compared with that in hypoxia group, hypoxic pulmonary artery hypertension was decreased in hypoxia ＋ stellate block group （P 〈 0.05）, CGRP was increased （P 〈 0.01）, and endothelin-1 was decreased remarkably （P 〈 0.05）. ② Level of BVE-NOS of the experimental rabbits was higher in stellate block group, hypoxia group and hypoxia ＋ stellate block group than that in the normal control group [（0.25±0.06）, （0.27±0.07）, （0.46± 0.12）, （0.14±0.03）, P 〈 0.05], and NOS level was higher in the hypoxia ＋ stellate block group than that in hypoxia group （P 〈 0.05）. CONCLUSION： Mean arterial pressure is decreased in rabbits with hypoxic pulmonary artery hypertension after stellate block and level of endothelin-1 is also decreased; however, levels of CGRP and NOS are increased respectively.
基金the financial support from the National Major Science and Technology Projects of China(Grant No.2017ZX05009-003)the National Natural Science Foundation of China(No.51404281)
文摘Stimulation of unconsolidated formations via horizontal wells has seen its vast implementation in the recent development of heavy oil reservoir to save the time and cost of preheating the reservoir before the steam-assisted gravity drainage(SAGD)process.A mathematical approach was proposed in this research that fully couples the hydraulic,mechanical and thermal responses of unconsolidated sandstone formations and also applies failure criteria for describing either shear dilation or tensile parting mechanism that generates microcracks.The approach was implemented to predict the porothermoelastic response of a pair of SAGD wells subject to injection and subsequent micro-fracturing using hot water.It was found that the predicted bottom hole pressures(BHPs)match closely with the field observed data.An elliptical dilation zone developed around the dual wells with relatively high pore pressure,porosity,permeability and temperature,implying good interwell hydraulic communication between both wells.The activation of microcracks dramatically accelerated the dissipation of pore pressure across the entire formation depth and also facilitated heat convection in between the dual wells,though to a lesser extent.In summary,the approach provides a convenient means to assist field engineers in the optimization of injection efficiency and evaluation of interference among multiple horizontal wells.
基金Special Research Fund for Plastic Surgery Hospital,Chinese Academy of Medical Sciences and Peking Union Medical College,No.B2018009Beijing Municipal Science&Technology Commission-Functional Urethral Reconstruction of Hypospadias by Tissue Transplantation,No.Z161100000516015.
文摘BACKGROUND Complex hypospadias is a surgical challenge.AIM To present the long-term outcomes of two-stage repair of complex hypospadias using a scrotal septal flap.METHODS This was a retrospective study of patients with complex hypospadias who were operated on between January 1st,2001,and January 1st,2019,at a single hospital using a scrotal septal flap(two-stage surgery)or prepuce flap(one-stage surgery;control group).In the scrotal group,the urethra was first repaired using oral mucosa;in the second stage,a scrotal septal flap was used as a second impermeable layer.Maximal/average urinary flow rates after surgery were compared.All patients were followed for≥6 mo(range:6-96 mo).RESULTS Ninety-seven patients were included(46 in the scrotal group and 51 in the prepuce group).The maximal urinary flow rate was 15.4±2.1 mL/s in the scrotal group and 14.3±3.0 mL/s in the control group(P=0.035).The average urinary flow rate was 8.4±2.3 mL/s in the scrotal group and 7.5±1.5 mL/s in the control group(P=0.019).The proportion of patients achieving good therapeutic effects was higher in the scrotal group than in the control group[24(52.2%)vs 16(31.4%),P=0.042;34(73.9%)vs 25(49.0%),P=0.014].The scrotal flap two-stage surgery was independently associated with a higher maximal urinary flow rate(OR=2.416,95%CI:1.026-5.689,P=0.044)and with a higher average flow rate(OR=2.484,95%CI:1.054-5.854,P=0.038).CONCLUSION In complex hypospadias,a scrotal septal flap could be a versatile and reliable option for resurfacing the penis.
基金supported by the National Natural Science Foundation of China(Grant No.51836009)。
文摘Increasing the phonon scattering center by adding nanoparticles to thermoelectric materials is an effective method of regulating the thermal conductivity.In this study,a series of Ca3 Co_(4)O_(9)/x wt.%CNTs(x=0,3,5,7,10)polycrystalline ceramic thermoelectric materials by adding carbon nanotubes(CNTs)were prepared with sol-gel method and cold-pressing sintering technology.The results of x-ray diffraction and field emission scanning electron microscopy show that the materials have a single-phase structure with high orientation and sheet like microstructure.The effect of adding carbon nanotubes to the thermoelectric properties of Ca_(3)Co_(4)O_(9)was systematically measured.The test results of thermoelectric properties show that the addition of carbon nanotubes reduces the electrical conductivity and Seebeck coefficient of the material.Nevertheless,the thermal conductivity of the samples with carbon nanotubes addition is lower than that of the samples without carbon nanotubes.At 625 K,the thermal conductivity of Ca3 Co_(4)O_(9)/10 wt.%CNTs sample is reduced to0.408 W·m^(-1)·K^(-1),which is about 73%lower than that of the original sample.When the three parameters are coupled,the figure of merit of Ca_(3)Co_(4)O_(9)/3 wt.%CNTs sample reaches 0.052,which is 29%higher than that of the original sample.This shows that an appropriate amount of carbon nanotubes addition can reduce the thermal conductivity of Ca_(3)Co_(4)O_(9)ceramic samples and improve their thermoelectric properties.
基金This study was financially supported by the Hunan Provin-cial Natural Science Foundation of China(Grant No.2022JJ10058)the National Natural Science Foundation of China(Grant Nos.12072369 and 52171166).The authors thank Dr.Xuehao Zheng from the ZKKF(Beijing)Science and Technology Company of China for supporting the SEM and TEM analyses.The authors would like to acknowledge Dr.Xiang Wu from KAIPLE Centre for Microscopy,Characterisation&Analysis(CMCA)of China for supporting the EBSD analyzes.
文摘In this study,the dynamic compressive response behavior of a body-centered cubic(BCC)single-phase TiZrNbV refractory high-entropy alloy(RHEA)was investigated under impact at speeds of 313-1584 m s^(-1)using two-stage,gas-gun-driven,high-speed plate-impact experiments;recovery sample analysis;and theoretical calculations.The strain rate and pressure were approximately 10^(7) s^(−1) and 5.07-29.37 GPa,respectively.The results showed that the TiZrNbV RHEA had a Hugoniot elastic limit of 4.12-5.86 GPa and a spall strength of 1.84-2.03 GPa.The initial yield strength of the alloy showed a strong strain-rate dependence and could be described by the modified Zerilli-Armstrong model,while the phonon-damping effect was the main reason for its high strain-rate sensitivity.Microstructural analysis showed that the dynamic deformation of the TiZrNbV RHEA was controlled by the dislocation slip,dislocation proliferation,intersection of the deformation bands,and grain refinement.The analysis also showed that the intergranular,transgranular,and mixed-type cracks dominated the spall failure of the material.The dynamic Hall-Petch effect and pinning from the lattice distortion led to high dynamic yield strength.The critical strain rate for the phonon drag effect was positively related to the relative atomic mass and local strain field of the metals.Within the experimental loading range,the RHEA showed good structural stability,and simultaneously,the theoretical calculation method for the equation of state based on a cold-energy mixture could accurately predict its shock-response behavior.The valence-electron concentration(VEC)had a direct effect on the shock-compression properties of the HEAs;higher VEC implied more difficulty in compressing the HEAs.The findings of this study provide insights into understanding the mechanical response characteristics of RHEAs under extreme conditions such as high-speed impact and ultrahigh strain-rate loading.
基金supported by the National Natural Science Foundation of China (Grant Nos. 62072309 and 6171101225).
文摘Activity hijacking is one of the most powerful attacks in Android. Though promising, all the prior activity hijacking attacks suffer from some limitations and have limited attack capabilities. They no longer pose security threats in recent Android due to the presence of effective defense mechanisms. In this work, we propose the first automated and adaptive activity hijacking attack, named VenomAttack, enabling a spectrum of customized attacks (e.g., phishing, spoofing, and DoS) on a large scale in recent Android, even the state-of-the-art defense mechanisms are deployed. Specifically, we propose to use hotpatch techniques to identify vulnerable devices and update attack payload without re-installation and re-distribution, hence bypassing offline detection. We present a newly-discovered flaw in Android and a bug in derivatives of Android, each of which allows us to check if a target app is running in the background or not, by which we can determine the right attack timing via a designed transparent activity. We also propose an automated fake activity generation approach, allowing large-scale attacks. Requiring only the common permission INTERNET, we can hijack activities at the right timing without destroying the GUI integrity of the foreground app. We conduct proof-of-concept attacks, showing that VenomAttack poses severe security risks on recent Android versions. The user study demonstrates the effectiveness of VenomAttack in real-world scenarios, achieving a high success rate (95%) without users’ awareness. That would call more attention to the stakeholders like Google.
基金funded by National Key R&D Program of China(2018YFD0900400)Guangdong Basic and Applied Basic Research Foundation(2019A1515110115).
文摘A 12-wk trial was conducted to compare the tolerance of tilapia to high carbohydrate and high lipid diets.Three isonitrogenous and isoenergetic diets,whose carbohydrate and lipid levels were the following:35.0%and 8%(control),44.2%and 4%(D1,high carbohydrate),and 25.8%and 12%(D2,high lipid),respectively.Three hundred tilapias(27±0.11 g)were fed the diets for 10 wk(4 replicates per group);72 fish from the D1 group were continually fed the D1(D1D1)and 72 fish from the D2 were continually fed the D2(D2D2)diet for 2 wk(3 replicates each group)to evaluate the tilapia's capacity to tolerate high carbohydrate and high lipid diets,respectively.Another 36 fish from D1 group were continually fed D2(D1D2)for comparison with D1D1 and D2D2 groups.In phase 1,hepatosomatic index,liver triglycerides(TG),glucose tolerance(GT)and crude protein in the whole body in D1 group were higher than those in D2 group(P<0.05).During phase 2,D1D1 group had lower feed intake and weight gain,as well as lower serum total protein and albumin than that of D2D2 group(P<0.05),while its liver glycogen was significantly higher than that in D1D2 and D2D2 groups(P<0.05).Moreover,serum glucose and GT were higher in D1D1 and D1D2 groups than those in D2D2 group(P<0.05).By contrast,D2D2 group had significantly higher intraperitoneal fat,subcutaneous adipose tissue(SCAT)and liver TG than those in D1D1 group(P<0.05).The mRNA expression of brain npy,hepatic nrf2,gst1 and hepatic transcriptomic data showed that immune-related genes(gama,mrc2,mhc2 and cd163),were downregulated in D1D1 group compared to D2D2 and D1D2 groups.Taken together:1)tilapia have higher tolerance to a high lipid diet than high carbohydrate diet;2)despite retention of glucose tolerance,the continuous feeding of D1 diet impaired tilapia's appetite,weight gain rate and host immune response;3)specific distri-bution of fat in intraperitoneal regions,SCAT and liver may be a risk-avoidance strategy in tilapia in response to a continuous D2 diet.
基金supported by the National Natural Science Foundation of China (81571025 and 81702461)the National Key Research and Development Program of China (2018YFC0116400)+6 种基金the International Cooperation Project from Shanghai Science Foundation (18410711300)Shanghai Science and Technology Development Funds (16JC1420100)the Shanghai Sailing Program (17YF1426600)STCSM (19QC1400600, 17411953300)the Shanghai Pujiang Program (19PJ1406800)the Shanghai Municipal Science and Technology Major Project (No.2018SHZDZX01) and ZJlabthe Interdisciplinary Program of Shanghai Jiao Tong University。
文摘Hydrocephalus is often treated with a cerebrospinal fluid shunt(CFS) for excessive amounts of cerebrospinal fluid in the brain.However,it is very difficult to distinguish whether the ventricular enlargement is due to hydrocephalus or other causes,such as brain atrophy after brain damage and surgery.The non-trivial evaluation of the consciousness level,along with a continuous drainage test of the lumbar cistern is thus clinically important before the decision for CFS is made.We studied 32 secondary mild hydrocephalus patients with different consciousness levels,who received T1 and diffusion tensor imaging magnetic resonance scans before and after lumbar cerebrospinal fluid drainage.We applied a novel machine-learning method to find the most discriminative features from the multi-modal neuroimages.Then,we built a regression model to regress the JFK Coma Recovery Scale-Revised(CRS-R) scores to quantify the level of consciousness.The experimental results showed that our method not only approximated the CRS-R scores but also tracked the temporal changes in individual patients.The regression model has high potential for the evaluation of consciousness in clinical practice.
基金supported by the National Natural Science Foundation of China Key Project (91748206)Dean’s Research Fundingthe Frontier Project of the Chinese Academy of Sciences
文摘Ga-based liquid metal has drawn attention in the field of interface science due to its large deformability.However, the spreading and shaping of liquid metal still remain a huge challenge to be solved owing to its large surface tension.Here, an intriguing synergistic oxidation-driven liquid metal fractal phenomenon was discovered and the general mechanisms were interpreted, which provides a new strategy for manipulating liquid metal.Experimental results demonstrate that the liquid metal placed on the graphite plate exhibited fractal characteristics with the addition of hydrogen peroxide.Here, it is of significance that hydrogen peroxide and graphite plates synergistically oxidize liquid metal.In addition, we predicted that liquid metal fractals can also be achieved on other eligible substrates based on the proposed general mechanism, which was confirmed by relevant experiments.Furthermore, the fractal dimensions of liquid metal fractal pattern were obtained and evaluated, distinguishing the synergistic oxidation-driven liquid metal fractals from the voltage-driven liquid metal fractals.Besides, we initially gave the best concentration range in which dendritic fractals can occur in order to guide practice.The ability to achieve liquid metal fractals promises rich opportunities in freely driving the liquid metal for soft machines and manufacturing the shape-reconfigurable electronic circuits.
基金This work was partially supported by the National Natural Science Foundation of China Key Project （Grant No. 91748206）, the Dean＇s Research Funding and the Frontier Project of the Chinese Academy of Sciences, as well as Beijing Municipal Science （Grant No. z151100003715002）.
文摘The hydrodynamic characteristics of hybrid fluid made of liquid metal/aqueous solution are elementary in the design and operation of conductive flow in a variety of newly emerging areas such as chip cooling, soft robot, and biomedical practices. chemical properties, such as In terms of physical and density, thermal conductivity and electrical conductivity, their huge differences between the two fluidic phases remain a big challenge for analyzing the hybrid flow behaviors. Besides, the liquid metal immersed in the solution can move and deform when administrated with non-contact electromagnetic force, or even induced by redox reaction, which is entirely different from the cases of conventional contact force. Owing to its remarkable capability in flow and deformation, liquid metal immersed in the solution is apt to deform on an extremely large scale, resulting in marked changes on its boundary and interface. However, the working mechanisms of the movement and deformation of liquid metal lack appropriate models to describe such scientific issues via a set of well-established unified equations. To promote investigations in this important area, the present paper is dedicated to summarizing this unconventional hydrodynamics from experiment, theory, and simulation. Typical experimental phenomena and basic working mechanisms are illustrated, followed by the movement and deformation theories to explain these phenomena. Several representative simulation methods are then proposed to tackle the governing functions of the electrohydrodynamics. Finally, prospects and challenges are raised, offering an insight into the new physics of the hybrid fluid under applied fields.
基金supported by the National Natural Science Foundation of China(Grant No.91748206)the National Key Research and Development Program of China(No.2020YFC0122301).
文摘Recent years have witnessed a rapid development of deformable devices and epidermal electronics that are in urgent request for flexible batteries.The intrinsically soft and ductile conductive electrode materials can offer pivotal hints in extending the lifespan of devices under frequent deformation.Featuring inherent liquidity,metal-licity,and biocompatibility,Ga-based room-temperature liquid metals(GBRTLMs)are potential candidates to fulfill the requirement of soft batteries.Herein,to illustrate the glamour of liquid components,high-temperature liquid metal batteries(HTLMBs)are briefly summarized from the aspects of principle,application,advantages,and drawbacks.Then,Ga-based liquid metals as main working electrodes in primary and secondary batteries are reviewed in terms of battery configurations,working mechanisms,and fiinctions.Next,Ga-based liquid metals as auxiliary working electrodes in lithium and nonlithium batteries are also discussed,which work as functional self-healing additives to alleviate the degradation and enhance the durability and capacity of the battery system.After that,Ga-based liquid metals as interconnecting electrodes in multi-scenarios including photovoltaics solar cells,generators,and supercapacitors(SCs)are interpreted,respectively.The summary and perspective of Ga-based liquid metals as diverse battery materials are also focused on.Finally,it was suggested that tremendous endeavors are yet to be made in exploring the innovative battery chemistry,inherent reaction mechanism,and multifunctional integration of Ga-based liquid metal battery systems in the coining future.
基金Foundation of China (Grant Nos. 51390473 and 51771203)the Key Research Program of Frontier Sciences, Chinese Academy of Sciences+1 种基金the National Key Research and Development Plan (Grant No. 2016YFB0701304)the Fundamental Research Fund for the Central Universities (Grant No. N140108001)
文摘Using scanning, transmission electron microscopy and aberration-corrected scanning transmission electron microscopy, we have studied the interactions between dislocations and twins in impact deformed polysynthetic twinned TiAl crystal. The 1/3 < 111] and 1/6 < 211] step dislocations on coherent twin boundaries reveal the interactions of glissile 1/2 < 101> dislocations with the coherent twin boundaries.An abnormal stacking fault was found adjacent to the coherent twin boundary. It has the same stacking sequence but different atom species in the [110] direction with an additional displacement of 1/4[110]in two neighboring {111} layers, and is likely induced by the slip of a 1/12[112](i.e. 1/4[110] + 1/6[211])dislocation.
基金supported by the National Nature Science Foundation of China under Key Project#91748206Shuimu Tsinghua Scholarship and China Postdoctoral Science Foundation:2021M691707.
文摘Liquid metal(LM)is a type of metal or alloy that has a low melting point near room temperature and exhibits the properties of both liquids and metals.Such unconventional materials have been gaining increasing attention within the scientific and industrial communities.Recently,fiber-shaped LM and its composites have especially attracted diverse interest owing to their unique merits,such as excellent conductivity,intrinsic stretchability,facile phase transition,and the ability to be woven or knitted into smart fabrics.This review is dedicated to summarizing different aspects of LM-based fibers,such as their material components,fabrication and design strategies,and remarkable applications by way of their representative properties.Typical fabrication approaches,such as 3D printing of pure LM wire,coating the LM shell on the surface of the fiber,injecting a LM core into hollow fibers,and spinning of LM and polymer hybrids have been comparatively illustrated.Moreover,emerging applications that primarily utilize LM fibers have been demonstrated.Finally,future directions and opportunities in the field are discussed.This categorization of LM fibers is expected to facilitate further investigation and practice in the coming society.
基金This work was supported by the National Key R&D Program of China(No.2018YFA0703800)the National Center for Mathematics and Interdisciplinary Sciences,Chinese Acad-emy of Sciences.
文摘The paper presents a novel control design,which is based on the idea of active disturbance rejection control(ADRC),for a kind of flexible aerocraft whose contolled variable cannot be measured directly.Since the original frame of ADRC can-not be directly applied,the paper puts forward a new extended state observer(ESO)and the corresponding ADRC law.In order to assign the poles of the closed loop system to ideal positions such that the vibration can be quickly suppressed,an elastic damping term is added into feedback law.The advantages of the new ESO for fectively estimating both the rigid mode and elastic mode from the measurements are discussed.Moreover,the analysis on the stabiliy.the relative stability and the steady state of the closed-loop system is given.Finally,the efectiveness and robustness of the proposed ADRC are verified by simulations.
基金This work was supported by the National Natural Science Foundation of China （51434008 （U1435204）, 51531005）, the China＇s Manned Space Station Project （Mission No： TGJZS00-2-RW024）, Dongguan Innovative Research Team Program （2014607134）, Shenyang Key R ＆ D and Technology Transfer Pro-gram （Z17-7-001）, Seed Fund Project of Shenyang National University Science and Technology Zone （20151019001） and Dou-ble-hundred Program of Shenyang Science and Technology Innova-tion Project （Y17-2-036）.
文摘A Ta wire-reinforced Zr-based bulk metallic glass composite with a new type of structure was prepared successfully by the method of liquid metal infiltration. Ta wires distribute uniformly in the metallic glass matrix in the form of spirals. The composite exhibits two yield stages under compressive stress, and the samples are compressed into thin pancakes. The micro-cracks originate at the interface between the Ta wire and the metallic glass matrix and propagate perpendicularly to the interface, which then induce multiple shear bands in the metallic glass matrix due to the stress concentration. Shear cracks form in the metallic glass matrix during the continued loading process as a result of the interaction of shear bands. Deformation bands of Ta wires occur under the impact of shear bands. The local stress fields in the composite are changed obviously due to the introduction of the spiral-formed reinforcements. The investigation of the deformation behavior and mechanism suggests a new method for the application of bulk metallic glass composites as the structural materials.
