[Objective] The aim was to get optimized conditions for date powder with good color and taste.[Method] The pectinase enzymolysis and vacuum freeze-drying technology were used in the extract process of date powder.[Res...[Objective] The aim was to get optimized conditions for date powder with good color and taste.[Method] The pectinase enzymolysis and vacuum freeze-drying technology were used in the extract process of date powder.[Result] The production boasts of superior quality were with rich fragrance and uniform particle under certain process conditions.The optimized conditions for pectinase enzymolysis were:the amount of pectinase reached to 0.1% of that of date syrup,enzymolysis temperature and time were 50 ℃ and 50 min respectively,the pH value was 4.0.The optimized conditions for vaccum freeze-drying were:10% altodextrin,three times volumn of water with the thickness of 7 mm.[Conclusion] The optimized conditions were obtained in this study to produce instant date powder from Ziziphus jujuba.展开更多
Colonoscopy represents a safe procedure that is widely used in medical practice either to diagnose or treat various gastrointestinal diseases.During the last few years,the incidence rate of perforations in colonoscopi...Colonoscopy represents a safe procedure that is widely used in medical practice either to diagnose or treat various gastrointestinal diseases.During the last few years,the incidence rate of perforations in colonoscopic procedures has increased,especially in therapeutic colonoscopies.The recent advancements in endoscopic techniques and gastrointestinal tumoral resection procedures such as endoscopic mucosal resection,endoscopic full-thickness resection,and endoscopic submucosal dissection(ESD)could be a risk factor for this increased risk.The incidence rate of mortality of serious colonoscopic perforations is 7.1%.The management plan for these perforations starts with conservative treatment in mild cases,endoscopic closure,and surgical management in severe cases.Recently,endoluminal vacuum therapy was found to be effective in the management of colorectal perforations and this has been reported in multiple case reports.This editorial provides an overview of the current guidelines for the management of iatrogenic colorectal perforations.These insights are from the perspectives of endoscopists and gastroenterologists.We also present a management algorithm based on the guidelines of the European Society of Gastrointestinal Endoscopy,the American Gastroenterological Association,and the World Society of Emergency Surgery.We also discussed in brief the use of endoluminal vacuum therapy in colorectal perforations.展开更多
Vacuum pressure vessels are one of the critical components in the aerospace field,and understanding the mechanical behavior feature is particularly important for safe operation.Therefore,it is meaningful to obtain the...Vacuum pressure vessels are one of the critical components in the aerospace field,and understanding the mechanical behavior feature is particularly important for safe operation.Therefore,it is meaningful to obtain the stress and strain distributions in the key positions of the vacuum tank,which can contribute to the safe performance assessment,operation efficiency,and fault analysis.Hence,this paper provides the distribution characteristics and variation rules of stress and tank strain of vacuum under different internal and external pressures through the elastic theoretical analysis and iteration method.The quasi-distributed fiber Bragg grating(FBG)sensors and the layout on the vacuum pressure vessel have thus been designed to monitor the whole vacuum extraction and loss process under three different loading conditions.Data analysis based on the theoretical results and monitoring information has further been conducted to validate the effectiveness of the proposed monitoring method for possible leakage defects.Research results indicate that the continuously monitoring data can quite sensitively and accurately characterize the microstrain variation features of the vacuum tank at different vacuum stages,and the loading-induced vibration effect should be carefully considered during the data interpretation.The study can provide scientific support for the vacuum loss state monitoring and safe performance assessment of the vacuum pressure vessels.展开更多
The low-melting glass of Bi2O_(3)-B2O_(3)-SiO_(2)(BiBSi)system was used for the first time for laser sealing of vacuum glazing.Under the condition of constant boron content,how the structure and properties vary with B...The low-melting glass of Bi2O_(3)-B2O_(3)-SiO_(2)(BiBSi)system was used for the first time for laser sealing of vacuum glazing.Under the condition of constant boron content,how the structure and properties vary with Bi/Si ratio in low-melting glass was investigated.In addition,the relationships between laser power,low-melting glass solder with different Bi/Si ratios and laser sealing shear strength were revealed.The results show that a decrease in the Bi/Si ratio can cause a contraction of the glass network of the low-melting glass,leading to an increase of its characteristic temperature and a decrease of its coefficient of thermal expansion.During laser sealing,the copper ions in the low-melting glass play an endothermic role.A change in the Bi/Si ratio will affect the valence state transition of the copper ions in the low-melting glass.The absorbance of the low-melting glass does not follow the expected correlation with the Bi/Si ratio,but shows a linear correlation with the content of divalent copper ions.The greater the concentration of divalent copper ions,the greater the absorbance of the low-melting glass,and the lower the laser power required for laser sealing.The shear strength of the low melting glass solder after laser sealing was tested,and it was found that the maximum shear strength of Z1 glass sample was the highest up to 2.67 MPa.展开更多
BACKGROUND A case study of multiple distinct levels of skipped thoracolumbar spine infection was reported in which 13 successful vacuum sealing drainage(VSD)surgeries were treated.CASE SUMMARY The patient underwent a ...BACKGROUND A case study of multiple distinct levels of skipped thoracolumbar spine infection was reported in which 13 successful vacuum sealing drainage(VSD)surgeries were treated.CASE SUMMARY The patient underwent a total of 13 procedures within our medical facility,including five performed under local anesthesia and eight performed under general anesthesia.The source of the ailment was ultimately identified as Enterobacter cloacae.After the last procedure,the patient's symptoms were alleviated,and the recovery process was satisfactory.Three months post-operation,the Japanese Orthopaedic Association scores had improved to 100%.Imageological examination revealed a satisfactory position of internal fixation,and the abnormal signals in the vertebral body and intervertebral space had been eliminated when compared to the pre-operative results.CONCLUSION The study demonstrates that the extreme lateral approach debridement combined with multiple VSD operations is a secure and successful method of treatment for recurrent spinal infection,providing an alternative to traditional surgery.展开更多
Background: The maternal and neonatal morbidity caused by prolonged labour, maternal exhaustion and other factors push clinicians to speed up the delivery process by employing equipment such as vacuum suction or force...Background: The maternal and neonatal morbidity caused by prolonged labour, maternal exhaustion and other factors push clinicians to speed up the delivery process by employing equipment such as vacuum suction or forceps to save the newborn. The purpose of this study was to determine the prevalence of vacuum-assisted vaginal delivery (VAVD) and its associated short-term maternal and neonatal outcomes at Ndola Teaching Hospital. Methods: A retrospective cross-sectional descriptive study through the analysis of routine data for women with singleton-term pregnancies who delivered by vacuum compared with spontaneous vaginal delivery was done at a tertiary hospital for the years 2020 and 2021. Chi-square and Logistic regression were used to investigate factors of vacuum delivery and to adjust for potential confounders. Results: Results showed that VAVD was mostly performed in women who had delayed second stage of labour (25.4%), maternal exhaustion (16.0%), foetal distress in the second stage of labour (12.3%). The overall VAVD prevalence was 3.7% (581/15591). Logistic regression showed that multiparous women were noted to be 87.5% (aOR 0.125;95% CI 0.025 - 0.629;p = 0.012) less likely to undergo VAVD compared to nulliparous women. Registrars were almost 6 times (aOR 5.650;95% CI 1.458 - 22.222, p = 0.012) more likely to conduct VAVD compared to midwives. Episiotomy was 3 times (aOR 3.390;95% CI 1.185 - 9.524;p Conclusion: The findings indicate the underutilisation of VAVD at NTH based on the low prevalence of 3.7%. VAVD outcomes were affected by multiparity, skill level and Episiotomy procedure, in addition, VAVD influenced admission to the NICU. Hence, there is a need to increase skills in VAVD among first-line healthcare workers such as midwives and intern doctors.展开更多
Based on the numerical solution of the time-dependent Dirac equation,we propose a method to observe in real time the ac Stark shift of a vacuum driven by an ultra-intense laser field.By overlapping the ultra-intense p...Based on the numerical solution of the time-dependent Dirac equation,we propose a method to observe in real time the ac Stark shift of a vacuum driven by an ultra-intense laser field.By overlapping the ultra-intense pump pulse with another zeptosecond probe pulse whose photon energy is smaller than 2mc^(2),electron–positron pair creation can be controlled by tuning the time delay between the pump and probe pulses.Since the pair creation rate depends sensitively on the instantaneous vacuum potential,one can reconstruct the ac Stark shift of the vacuum potential according to the time-delay-dependent pair creation rate.展开更多
Establishing a base on the Moon is one of the new goals of human lunar exploration in recent years.Sintered lunar regolith is one of the most potential building materials for lunar bases.The physical,mechanical and th...Establishing a base on the Moon is one of the new goals of human lunar exploration in recent years.Sintered lunar regolith is one of the most potential building materials for lunar bases.The physical,mechanical and thermal properties of sintered lunar regolith are vital performance indices for the structural design of a lunar base and analysis of many critical mechanical and thermal issues.In this study,the HUST-1 lunar regolith simulant(HLRS)was sintered at 1030,1040,1050,1060,1070,and 1080℃.The effect of sintering temperature on the compressive strength was investigated,and the exact value of the optimum vacuum sintering temperature was determined between 1040 and 1060℃.Then,the microstructure and material composition of vacuum sintered HLRS at different temperatures were characterized.It was found that the sintering temperature has no significant effect on the mineral composition in the temperature range of 1030-1080℃.Besides,the heat capacity,thermal conductivity,and coefficient of thermal expansion(CTE)of vacuum sintered HLRS at different temperatures were investigated.Specific heat capacity of sintered samples increases with the increase of test temperature within the temperature range from-75 to 145℃.Besides,the thermal conductivity of the sintered sample is proportional to density.Finally,the two temperatures of 1040 and 1050℃were selected for a more detailed study of mechanical properties.The results showed that compressive strength of sintered sample is much higher than tensile strength.This study reveals the effects of sintering temperature on the physical,mechanical and thermal properties of vacuum sintered HLRS,and these material parameters will provide support for the construction of future lunar bases.展开更多
In this paper,we study the one-dimensional motion of viscous gas near a vacuum,with the gas connecting to a vacuum state with a jump in density.The interface behavior,the pointwise decay rates of the density function ...In this paper,we study the one-dimensional motion of viscous gas near a vacuum,with the gas connecting to a vacuum state with a jump in density.The interface behavior,the pointwise decay rates of the density function and the expanding rates of the interface are obtained with the viscosity coefficientμ(ρ)=ρ^(α)for any 0<α<1;this includes the timeweighted boundedness from below and above.The smoothness of the solution is discussed.Moreover,we construct a class of self-similar classical solutions which exhibit some interesting properties,such as optimal estimates.The present paper extends the results in[Luo T,Xin Z P,Yang T.SIAM J Math Anal,2000,31(6):1175-1191]to the jump boundary conditions case with density-dependent viscosity.展开更多
Manufacturing process,diffusion co-efficient and areal capacity are the three main criteria for regulating thick electrodes for lithium-ion batteries(LIBs).However,simultaneously regulating these criteria for LIBs is ...Manufacturing process,diffusion co-efficient and areal capacity are the three main criteria for regulating thick electrodes for lithium-ion batteries(LIBs).However,simultaneously regulating these criteria for LIBs is desirable but remains a significant challenge.In this work,niobium pentoxide(Nb_(2)O_(5))anode and lithium iron phosphate(LiFePO_(4))cathode materials were chosen as the model materials and demonstrate that these three parameters can be simultaneously modulated by incorporation of micro-carbon fibers(MCF)and carbon nanotubes(CNT)with both Nb_(2)O_(5) and LFP via vacuum filtration approach.Both as-prepared MNC-20 anode and MLC-20 cathode achieves high reversible areal capacity of≈5.4 m A h cm^(-2)@0.1 C and outstanding Li-ion diffusion coefficients of≈10~(-8)cm~2 s~(-1)in the half-cell configuration.The assembled MNC-20‖MLC-20 full cell LIB delivers maximum energy and power densities of244.04 W h kg^(-1)and 108.86 W kg^(-1),respectively.The excellent electrochemical properties of the asprepared thick electrodes can be attributed to the highly conductive,mechanical compactness and multidimensional mutual effects of the MCF,CNT and active materials that facilitates rapid Li-ion diffusion kinetics.Furthermore,electrochemical impedance spectroscopy(EIS),symmetric cells analysis,and insitu Raman techniques clearly validates the enhanced Li-ion diffusion kinetics in the present architecture.展开更多
A double-well potential model is proposed for the pionic deuterium that enables to calculate the energy split, the potential barrier height and estimate the pion tetrahedron edge length. We propose that pion tetrahedr...A double-well potential model is proposed for the pionic deuterium that enables to calculate the energy split, the potential barrier height and estimate the pion tetrahedron edge length. We propose that pion tetrahedrons, π<sup>Td</sup> = u<sub>d</sub>~</sup>dũ, play a central role in the Yukawa interaction by enabling quark exchange reactions between protons and neutrons by tunneling through a potential barrier. A vacuum polarization Feynman diagram is proposed for the π<sup>Td</sup> having chains of fermion loops for the two valence quarks and anti-quarks connected by gluons. With a higher order vacuum polarization diagram, the d and u quark loops are interleaved and the chiral symmetry is broken dynamically. The proposed π<sup>Td</sup> vacuum polarization integral does not diverge in both the IR and UV limits and vanishes in the limit of an infinite pion tetrahedron condensate. We propose a new Delbruck scattering Feynman diagram that includes d and u quark and anti-quark interleaved loops. We further propose that conversion of gravitons to photons may occur via quark and anti-quark loops that describe the pion tetrahedrons dynamics in the vacuum and may also transfer gravitational waves.展开更多
A vacuum ultraviolet(VUV)spectroscopy with a focal length of 1 m has been engineered specifically for observing edge impurity emissions in Experimental Advanced Superconducting Tokamak(EAST).In this study,wavelength c...A vacuum ultraviolet(VUV)spectroscopy with a focal length of 1 m has been engineered specifically for observing edge impurity emissions in Experimental Advanced Superconducting Tokamak(EAST).In this study,wavelength calibration for the VUV spectroscopy is achieved utilizing a zinc lamp.The grating angle and charge-coupled device(CCD)position are carefully calibrated for different wavelength positions.The wavelength calibration of the VUV spectroscopy is crucial for improving the accuracy of impurity spectral data,and is required to identify more impurity spectral lines for impurity transport research.Impurity spectra of EAST plasmas have also been obtained in the wavelength range of 50–300 nm with relatively high spectral resolution.It is found that the impurity emissions in the edge region are still dominated by low-Z impurities,such as carbon,oxygen,and nitrogen,albeit with the application of fulltungsten divertors on the EAST tokamak.展开更多
Understanding the coking behaviors has been considered to be really essential for developing better vacuum residue processing technologies.A battery of thermal cracking tests of typical vacuum residue at 410℃ with va...Understanding the coking behaviors has been considered to be really essential for developing better vacuum residue processing technologies.A battery of thermal cracking tests of typical vacuum residue at 410℃ with various reaction time were performed to evaluate the coke formation process.The total yields of ideal components including naphtha,atmospheric gas oil(AGO)and vacuum gas oil(VGO)of thermal cracking reactions increased from 10.89%to 40.81%,and the conversion ratios increased from8.05%to 43.33%with increasing the reaction time from 10 to 70 min.The asphaltene content increased from 12.14%to a maximum of 22.39%and then decreased,and this maximum of asphaltene content occurred at the end of the coking induction period.The asphaltenes during the coking induction period,at the end and after coking induction period of those tested thermal cracking reactions were characterized to disclose the structure changing rules for coke formation process,and the coke formation pathways were discussed to reveal the coke formation process at molecular level.展开更多
In this study, the mechanisms of the anode phenomena and anode erosion with various contact materials were investigated. Arc parameters were calculated, and the anode temperature was predicted with a transient self-co...In this study, the mechanisms of the anode phenomena and anode erosion with various contact materials were investigated. Arc parameters were calculated, and the anode temperature was predicted with a transient self-consistent model. The simulation results predicted a constricted arc column and obvious anode phenomena in Cu–Cr alloy contacts than in W–Cu alloy contacts.This observation could be the reason for the concentrated anode erosion in Cu–Cr alloys. For the contacts made by pure tungsten(W) and W–Cu alloy, the anode temperature increased rapidly because of the low specific heat of W. However, the maximum energy flux from the arc column to the anode surface was lower than in other cases. The simulation results were compared with experimental results.展开更多
Magnesium and magnesium thin alloy films were deposited using a thermionic vacuum arc(TVA),which has multiple applications in the field of metallic electrodes for diodes and batteries or active corrosion protection.An...Magnesium and magnesium thin alloy films were deposited using a thermionic vacuum arc(TVA),which has multiple applications in the field of metallic electrodes for diodes and batteries or active corrosion protection.An improved laser-induced TVA(LTVA)method favors the crystallization processes of the deposited magnesium-based films because the interaction between laser and plasma discharge changes the thermal energy during photonic processes due to the local temperature variation.Plasma diagnosis based on current discharge measurements suggests an inelastic collision between the laser beam and the atoms from the plasma discharge.The morphology and surface properties of the obtained thin films differ between these two methods.While the amorphous character is dominant for TVA thin films,enabling a smooth surface,the LTVA method produces rough surfaces with prominent crystallinity,less hydrophobic character and lower surface energy.The smooth surfaces obtained by the TVA methods produce metallic electrodes with good electrical contact,ensuring better diodes and battery charge transport.Both methods allow uniform magnesium alloys to be obtained,but the laser used in the LTVA on the discharge plasma controls the added metal or element ratio.展开更多
The Theory of General Singularity is presented, unifying quantum field theory, general relativity, and the standard model. This theory posits phonons as fundamental excitations in a quantum vacuum, modeled as a Bose-E...The Theory of General Singularity is presented, unifying quantum field theory, general relativity, and the standard model. This theory posits phonons as fundamental excitations in a quantum vacuum, modeled as a Bose-Einstein condensate. Through key equations, the role of phonons as intermediaries between matter, energy, and spacetime geometry is demonstrated. The theory expands Einsteins field equations to differentiate between visible and dark matter, and revises the standard model by incorporating phonons. It addresses dark matter, dark energy, gravity, and phase transitions, while making testable predictions. The theory proposes that singularities, the essence of particles and black holes, are quantum entities ubiquitous in nature, constituting the very essence of elementary particles, seen as micro black holes or quantum fractal structures of spacetime. As the theory is refined with increasing mathematical rigor, it builds upon the foundation of initial physical intuition, connecting the spacetime continuum of general relativity with the hydrodynamics of the quantum vacuum. Inspired by the insights of Tesla and Majorana, who believed that physical intuition justifies the infringement of mathematical rigor in the early stages of theory development, this work aims to advance the understanding of the fundamental laws of the universe and the perception of reality.展开更多
A novel micro-nano Ti−10Cu−10Ni−8Al−8Nb−4Zr−1.5Hf filler was used to vacuum braze Ti−47Al−2Nb−2Cr−0.15B alloy at 1160−1220℃ for 30 min.The interfacial microstructure and formation mechanism of TiAl joints and the rel...A novel micro-nano Ti−10Cu−10Ni−8Al−8Nb−4Zr−1.5Hf filler was used to vacuum braze Ti−47Al−2Nb−2Cr−0.15B alloy at 1160−1220℃ for 30 min.The interfacial microstructure and formation mechanism of TiAl joints and the relationships among brazing temperature,interfacial microstructure and joint strength were emphatically investigated.Results show that the TiAl joints brazed at 1160 and 1180℃ possess three interfacial layers and mainly consist of α_(2)-Ti_(3)Al,τ_(3)-Al_(3)NiTi_(2) and Ti_(2)Ni,but the brazing seams are no longer layered and Ti_(2)Ni is completely replaced by the uniformly distributed τ_(3)-Al_(3)NiTi_(2) at 1200 and 1220℃ due to the destruction of α_(2)-Ti_(3)Al barrier layer.This transformation at 1200℃ obviously improves the tensile strength of the joint and obtains a maximum of 343 MPa.Notably,the outward diffusion of Al atoms from the dissolution of TiAl substrate dominates the microstructure evolution and tensile strength of the TiAl joint at different brazing temperatures.展开更多
The vacuum-assisted prefabricated horizontal drain offers a promising method for strengthening soil slurry,allowing simultaneous filling and vacuum-dewatering via staged construction.However,there is limited research ...The vacuum-assisted prefabricated horizontal drain offers a promising method for strengthening soil slurry,allowing simultaneous filling and vacuum-dewatering via staged construction.However,there is limited research on the unique characteristics of staged filling.This study aims to investigate the vacuum consolidation process of staged-filled soil slurry through laboratory model tests and numerical simulations,also assessing the impact of anionic polyacrylamide.Comparative analyses are conducted between vacuum consolidation with and without anionic polyacrylamide,as well as self-weight consolidation without anionic polyacrylamide.Results reveal contour lines of excess pore pressure,water content,and soil strength forming an ellipse around the prefabricated horizontal drain board.During the consolidation process,a higher degree of consolidation,lower water content,and higher soil strength were observed closer to the prefabricated horizontal drain board.After treatment,the uppermost filling layer exhibits an average water content that was approximately 40%higher than the lower filling layer,and its average strength was about 60%lower.This discrepancy is primarily due to the absence of sealing on the top surface and the relatively short vacuum consolidation time caused by staged filling.The introduction of anionic polyacrylamide-induced flocculation significantly improves the initial consolidation rate but minimally affects the dewatering capacity of vacuum preloading.Using flocculant can enhance both the staged filling rate and soil strength(by 1e2 times).Additionally,employing a staggered arrangement between different prefabricated horizontal drain layers is advisable to prevent top-down penetration in areas with low soil strength.展开更多
The trajectory of the compact torus(CT)within a tokamak discharge is crucial to fueling.In this study,we developed a penetration model with a vacuum magnetic field region to accurately determine CT trajectories in tok...The trajectory of the compact torus(CT)within a tokamak discharge is crucial to fueling.In this study,we developed a penetration model with a vacuum magnetic field region to accurately determine CT trajectories in tokamak discharges.This model was used to calculate the trajectory and penetration parameters of CT injections by applying both perpendicular and tangential injection schemes in both HL-2A and ITER tokamaks.For perpendicular injection along the tokamak's major radius direction from the outboard,CTs with the same injection parameters exhibited a 0.08 reduction in relative penetration depth when injected into HL-2A and a 0.13reduction when injected into ITER geometry when considering the vacuum magnetic field region compared with cases where this region was not considered.In addition,we proposed an optimization method for determining the CT's initial injection velocity to accurately calculate the initial injection velocity of CTs for central fueling in tokamaks.Furthermore,this paper discusses schemes for the tangential injection of CT into tokamak discharges.The optimal injection angle and CT magnetic moment direction for injection into both HL-2A and ITER were determined through numerical simulations.Finally,the kinetic energy loss occurring when the CT penetrated the vacuum magnetic field region in ITER was reduced byΔEk=975.08 J by optimizing the injection angle for the CT injected into ITER.These results provide valuable insights for optimizing injection angles in fusion experiments.Our model closely represents actual experimental scenarios and can assist the design of CT parameters.展开更多
The development of advanced aircraft relies on high performance thermal-structural materials,and carbon/carbon com-posites(C/C)composited with ultrahigh-temperature ceramics are ideal candidates.However,the traditiona...The development of advanced aircraft relies on high performance thermal-structural materials,and carbon/carbon com-posites(C/C)composited with ultrahigh-temperature ceramics are ideal candidates.However,the traditional routes of compositing are either inefficient and expensive or lead to a non-uniform distribution of ceramics in the matrix.Compared with the traditional C/C-ZrC-SiC composites prepared by the reactive melt infiltration of ZrSi_(2),C/C-ZrB_(2)-ZrC-SiC composites prepared by the vacuum infiltration of ZrB_(2) combined with reactive melt infiltration have the higher content and more uniform distribution of the introduced ceramic phases.The mass and linear ablation rates of the C/C-ZrB_(2)-ZrC-SiC composites were respectively 68.9%and 29.7%lower than those of C/C-ZrC-SiC composites prepared by reactive melt infiltration.The ablation performance was improved because the volatilization of B_(2)O_(3),removes some of the heat,and the more uniformly distributed ZrO_(2),that helps produce a ZrO2-SiO2 continu-ous protective layer,hinders oxygen infiltration and decreases ablation.展开更多
基金Supported by Key Projects of Henan Institute of Science and Technology (06013)
文摘[Objective] The aim was to get optimized conditions for date powder with good color and taste.[Method] The pectinase enzymolysis and vacuum freeze-drying technology were used in the extract process of date powder.[Result] The production boasts of superior quality were with rich fragrance and uniform particle under certain process conditions.The optimized conditions for pectinase enzymolysis were:the amount of pectinase reached to 0.1% of that of date syrup,enzymolysis temperature and time were 50 ℃ and 50 min respectively,the pH value was 4.0.The optimized conditions for vaccum freeze-drying were:10% altodextrin,three times volumn of water with the thickness of 7 mm.[Conclusion] The optimized conditions were obtained in this study to produce instant date powder from Ziziphus jujuba.
文摘Colonoscopy represents a safe procedure that is widely used in medical practice either to diagnose or treat various gastrointestinal diseases.During the last few years,the incidence rate of perforations in colonoscopic procedures has increased,especially in therapeutic colonoscopies.The recent advancements in endoscopic techniques and gastrointestinal tumoral resection procedures such as endoscopic mucosal resection,endoscopic full-thickness resection,and endoscopic submucosal dissection(ESD)could be a risk factor for this increased risk.The incidence rate of mortality of serious colonoscopic perforations is 7.1%.The management plan for these perforations starts with conservative treatment in mild cases,endoscopic closure,and surgical management in severe cases.Recently,endoluminal vacuum therapy was found to be effective in the management of colorectal perforations and this has been reported in multiple case reports.This editorial provides an overview of the current guidelines for the management of iatrogenic colorectal perforations.These insights are from the perspectives of endoscopists and gastroenterologists.We also present a management algorithm based on the guidelines of the European Society of Gastrointestinal Endoscopy,the American Gastroenterological Association,and the World Society of Emergency Surgery.We also discussed in brief the use of endoluminal vacuum therapy in colorectal perforations.
基金supported by the Provincial Scientific Projects of Gansu(22YF7GA182)Innovation Foundation of Provincial Education Department of Gansu(2024B-005)Fundamental Research Funds for the Central Universities(No.lzujbky-2024-05).
文摘Vacuum pressure vessels are one of the critical components in the aerospace field,and understanding the mechanical behavior feature is particularly important for safe operation.Therefore,it is meaningful to obtain the stress and strain distributions in the key positions of the vacuum tank,which can contribute to the safe performance assessment,operation efficiency,and fault analysis.Hence,this paper provides the distribution characteristics and variation rules of stress and tank strain of vacuum under different internal and external pressures through the elastic theoretical analysis and iteration method.The quasi-distributed fiber Bragg grating(FBG)sensors and the layout on the vacuum pressure vessel have thus been designed to monitor the whole vacuum extraction and loss process under three different loading conditions.Data analysis based on the theoretical results and monitoring information has further been conducted to validate the effectiveness of the proposed monitoring method for possible leakage defects.Research results indicate that the continuously monitoring data can quite sensitively and accurately characterize the microstrain variation features of the vacuum tank at different vacuum stages,and the loading-induced vibration effect should be carefully considered during the data interpretation.The study can provide scientific support for the vacuum loss state monitoring and safe performance assessment of the vacuum pressure vessels.
基金Funded by the National Natural Science Foundation of China(No.52472012)Opening Project of State Silica-Based Materials Laboratory of Anhui Province(No.2022KF11)the Research and Development of Glass Powder for Laser Sealing and Its Sealing Technology(No.K24556)。
文摘The low-melting glass of Bi2O_(3)-B2O_(3)-SiO_(2)(BiBSi)system was used for the first time for laser sealing of vacuum glazing.Under the condition of constant boron content,how the structure and properties vary with Bi/Si ratio in low-melting glass was investigated.In addition,the relationships between laser power,low-melting glass solder with different Bi/Si ratios and laser sealing shear strength were revealed.The results show that a decrease in the Bi/Si ratio can cause a contraction of the glass network of the low-melting glass,leading to an increase of its characteristic temperature and a decrease of its coefficient of thermal expansion.During laser sealing,the copper ions in the low-melting glass play an endothermic role.A change in the Bi/Si ratio will affect the valence state transition of the copper ions in the low-melting glass.The absorbance of the low-melting glass does not follow the expected correlation with the Bi/Si ratio,but shows a linear correlation with the content of divalent copper ions.The greater the concentration of divalent copper ions,the greater the absorbance of the low-melting glass,and the lower the laser power required for laser sealing.The shear strength of the low melting glass solder after laser sealing was tested,and it was found that the maximum shear strength of Z1 glass sample was the highest up to 2.67 MPa.
基金Supported by Natural Science Foundation of Shandong Province,No.ZR2023MH331.
文摘BACKGROUND A case study of multiple distinct levels of skipped thoracolumbar spine infection was reported in which 13 successful vacuum sealing drainage(VSD)surgeries were treated.CASE SUMMARY The patient underwent a total of 13 procedures within our medical facility,including five performed under local anesthesia and eight performed under general anesthesia.The source of the ailment was ultimately identified as Enterobacter cloacae.After the last procedure,the patient's symptoms were alleviated,and the recovery process was satisfactory.Three months post-operation,the Japanese Orthopaedic Association scores had improved to 100%.Imageological examination revealed a satisfactory position of internal fixation,and the abnormal signals in the vertebral body and intervertebral space had been eliminated when compared to the pre-operative results.CONCLUSION The study demonstrates that the extreme lateral approach debridement combined with multiple VSD operations is a secure and successful method of treatment for recurrent spinal infection,providing an alternative to traditional surgery.
文摘Background: The maternal and neonatal morbidity caused by prolonged labour, maternal exhaustion and other factors push clinicians to speed up the delivery process by employing equipment such as vacuum suction or forceps to save the newborn. The purpose of this study was to determine the prevalence of vacuum-assisted vaginal delivery (VAVD) and its associated short-term maternal and neonatal outcomes at Ndola Teaching Hospital. Methods: A retrospective cross-sectional descriptive study through the analysis of routine data for women with singleton-term pregnancies who delivered by vacuum compared with spontaneous vaginal delivery was done at a tertiary hospital for the years 2020 and 2021. Chi-square and Logistic regression were used to investigate factors of vacuum delivery and to adjust for potential confounders. Results: Results showed that VAVD was mostly performed in women who had delayed second stage of labour (25.4%), maternal exhaustion (16.0%), foetal distress in the second stage of labour (12.3%). The overall VAVD prevalence was 3.7% (581/15591). Logistic regression showed that multiparous women were noted to be 87.5% (aOR 0.125;95% CI 0.025 - 0.629;p = 0.012) less likely to undergo VAVD compared to nulliparous women. Registrars were almost 6 times (aOR 5.650;95% CI 1.458 - 22.222, p = 0.012) more likely to conduct VAVD compared to midwives. Episiotomy was 3 times (aOR 3.390;95% CI 1.185 - 9.524;p Conclusion: The findings indicate the underutilisation of VAVD at NTH based on the low prevalence of 3.7%. VAVD outcomes were affected by multiparity, skill level and Episiotomy procedure, in addition, VAVD influenced admission to the NICU. Hence, there is a need to increase skills in VAVD among first-line healthcare workers such as midwives and intern doctors.
基金supported by the National Natural Science Foundation of China(Grant Nos.12304341 and 11974419)the National Key R&D Program of China(Grant Nos.2021YFA1601700 and 2018YFA0404802)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDA25051000).
文摘Based on the numerical solution of the time-dependent Dirac equation,we propose a method to observe in real time the ac Stark shift of a vacuum driven by an ultra-intense laser field.By overlapping the ultra-intense pump pulse with another zeptosecond probe pulse whose photon energy is smaller than 2mc^(2),electron–positron pair creation can be controlled by tuning the time delay between the pump and probe pulses.Since the pair creation rate depends sensitively on the instantaneous vacuum potential,one can reconstruct the ac Stark shift of the vacuum potential according to the time-delay-dependent pair creation rate.
基金supported by the National Key Research and Development Program of China(Nos.2021YFF0500300 and 2023YFB3711300)the Strategic Research and Consulting Project of the Chinese Academy of Engineering(Nos.2023-XZ-90 and 2023-JB-09-10).
文摘Establishing a base on the Moon is one of the new goals of human lunar exploration in recent years.Sintered lunar regolith is one of the most potential building materials for lunar bases.The physical,mechanical and thermal properties of sintered lunar regolith are vital performance indices for the structural design of a lunar base and analysis of many critical mechanical and thermal issues.In this study,the HUST-1 lunar regolith simulant(HLRS)was sintered at 1030,1040,1050,1060,1070,and 1080℃.The effect of sintering temperature on the compressive strength was investigated,and the exact value of the optimum vacuum sintering temperature was determined between 1040 and 1060℃.Then,the microstructure and material composition of vacuum sintered HLRS at different temperatures were characterized.It was found that the sintering temperature has no significant effect on the mineral composition in the temperature range of 1030-1080℃.Besides,the heat capacity,thermal conductivity,and coefficient of thermal expansion(CTE)of vacuum sintered HLRS at different temperatures were investigated.Specific heat capacity of sintered samples increases with the increase of test temperature within the temperature range from-75 to 145℃.Besides,the thermal conductivity of the sintered sample is proportional to density.Finally,the two temperatures of 1040 and 1050℃were selected for a more detailed study of mechanical properties.The results showed that compressive strength of sintered sample is much higher than tensile strength.This study reveals the effects of sintering temperature on the physical,mechanical and thermal properties of vacuum sintered HLRS,and these material parameters will provide support for the construction of future lunar bases.
基金supported by the NSFC(11931013)the GXNSF(2022GXNSFDA035078)。
文摘In this paper,we study the one-dimensional motion of viscous gas near a vacuum,with the gas connecting to a vacuum state with a jump in density.The interface behavior,the pointwise decay rates of the density function and the expanding rates of the interface are obtained with the viscosity coefficientμ(ρ)=ρ^(α)for any 0<α<1;this includes the timeweighted boundedness from below and above.The smoothness of the solution is discussed.Moreover,we construct a class of self-similar classical solutions which exhibit some interesting properties,such as optimal estimates.The present paper extends the results in[Luo T,Xin Z P,Yang T.SIAM J Math Anal,2000,31(6):1175-1191]to the jump boundary conditions case with density-dependent viscosity.
基金supported by the Science and Technology Innovation Program of Hunan Province(2022WZ1012)the Hunan Joint International Laboratory of Advanced Materials and Technology for Clean Energy(2020CB1007)the Natural Science Foundation of Guangzhou(202201020147)。
文摘Manufacturing process,diffusion co-efficient and areal capacity are the three main criteria for regulating thick electrodes for lithium-ion batteries(LIBs).However,simultaneously regulating these criteria for LIBs is desirable but remains a significant challenge.In this work,niobium pentoxide(Nb_(2)O_(5))anode and lithium iron phosphate(LiFePO_(4))cathode materials were chosen as the model materials and demonstrate that these three parameters can be simultaneously modulated by incorporation of micro-carbon fibers(MCF)and carbon nanotubes(CNT)with both Nb_(2)O_(5) and LFP via vacuum filtration approach.Both as-prepared MNC-20 anode and MLC-20 cathode achieves high reversible areal capacity of≈5.4 m A h cm^(-2)@0.1 C and outstanding Li-ion diffusion coefficients of≈10~(-8)cm~2 s~(-1)in the half-cell configuration.The assembled MNC-20‖MLC-20 full cell LIB delivers maximum energy and power densities of244.04 W h kg^(-1)and 108.86 W kg^(-1),respectively.The excellent electrochemical properties of the asprepared thick electrodes can be attributed to the highly conductive,mechanical compactness and multidimensional mutual effects of the MCF,CNT and active materials that facilitates rapid Li-ion diffusion kinetics.Furthermore,electrochemical impedance spectroscopy(EIS),symmetric cells analysis,and insitu Raman techniques clearly validates the enhanced Li-ion diffusion kinetics in the present architecture.
文摘A double-well potential model is proposed for the pionic deuterium that enables to calculate the energy split, the potential barrier height and estimate the pion tetrahedron edge length. We propose that pion tetrahedrons, π<sup>Td</sup> = u<sub>d</sub>~</sup>dũ, play a central role in the Yukawa interaction by enabling quark exchange reactions between protons and neutrons by tunneling through a potential barrier. A vacuum polarization Feynman diagram is proposed for the π<sup>Td</sup> having chains of fermion loops for the two valence quarks and anti-quarks connected by gluons. With a higher order vacuum polarization diagram, the d and u quark loops are interleaved and the chiral symmetry is broken dynamically. The proposed π<sup>Td</sup> vacuum polarization integral does not diverge in both the IR and UV limits and vanishes in the limit of an infinite pion tetrahedron condensate. We propose a new Delbruck scattering Feynman diagram that includes d and u quark and anti-quark interleaved loops. We further propose that conversion of gravitons to photons may occur via quark and anti-quark loops that describe the pion tetrahedrons dynamics in the vacuum and may also transfer gravitational waves.
基金partially supported by National Natural Science Foundation of China(Nos.U23A2077,12175278,12205072)the National Magnetic Confinement Fusion Science Program of China(Nos.2019YFE0304002,2018YFE0303103)+2 种基金the Comprehensive Research Facility for Fusion Technology Program of China(No.2018-000052-73-01-001228)Major Science and Technology Infrastructure Maintenance and Reconstruction Projects of the Chinese Academy of Sciences(2021)the University Synergy Innovation Program of Anhui Province(No.GXXT2021-029)。
文摘A vacuum ultraviolet(VUV)spectroscopy with a focal length of 1 m has been engineered specifically for observing edge impurity emissions in Experimental Advanced Superconducting Tokamak(EAST).In this study,wavelength calibration for the VUV spectroscopy is achieved utilizing a zinc lamp.The grating angle and charge-coupled device(CCD)position are carefully calibrated for different wavelength positions.The wavelength calibration of the VUV spectroscopy is crucial for improving the accuracy of impurity spectral data,and is required to identify more impurity spectral lines for impurity transport research.Impurity spectra of EAST plasmas have also been obtained in the wavelength range of 50–300 nm with relatively high spectral resolution.It is found that the impurity emissions in the edge region are still dominated by low-Z impurities,such as carbon,oxygen,and nitrogen,albeit with the application of fulltungsten divertors on the EAST tokamak.
文摘Understanding the coking behaviors has been considered to be really essential for developing better vacuum residue processing technologies.A battery of thermal cracking tests of typical vacuum residue at 410℃ with various reaction time were performed to evaluate the coke formation process.The total yields of ideal components including naphtha,atmospheric gas oil(AGO)and vacuum gas oil(VGO)of thermal cracking reactions increased from 10.89%to 40.81%,and the conversion ratios increased from8.05%to 43.33%with increasing the reaction time from 10 to 70 min.The asphaltene content increased from 12.14%to a maximum of 22.39%and then decreased,and this maximum of asphaltene content occurred at the end of the coking induction period.The asphaltenes during the coking induction period,at the end and after coking induction period of those tested thermal cracking reactions were characterized to disclose the structure changing rules for coke formation process,and the coke formation pathways were discussed to reveal the coke formation process at molecular level.
基金supported by the Sichuan Science and Technology Program (No. 2024NSFSC0867)National Natural Science Foundation of China (No. 52377157)。
文摘In this study, the mechanisms of the anode phenomena and anode erosion with various contact materials were investigated. Arc parameters were calculated, and the anode temperature was predicted with a transient self-consistent model. The simulation results predicted a constricted arc column and obvious anode phenomena in Cu–Cr alloy contacts than in W–Cu alloy contacts.This observation could be the reason for the concentrated anode erosion in Cu–Cr alloys. For the contacts made by pure tungsten(W) and W–Cu alloy, the anode temperature increased rapidly because of the low specific heat of W. However, the maximum energy flux from the arc column to the anode surface was lower than in other cases. The simulation results were compared with experimental results.
基金funded by CCDI-UEFISCDI project number PN-III-P2-2.1-PED-2021-0828,within PNCDI III and by the program Johannes Amos Comenius(cofunded by the European Union)QM4ST,project number CZ.02.01.01/00/22_008/0004572.
文摘Magnesium and magnesium thin alloy films were deposited using a thermionic vacuum arc(TVA),which has multiple applications in the field of metallic electrodes for diodes and batteries or active corrosion protection.An improved laser-induced TVA(LTVA)method favors the crystallization processes of the deposited magnesium-based films because the interaction between laser and plasma discharge changes the thermal energy during photonic processes due to the local temperature variation.Plasma diagnosis based on current discharge measurements suggests an inelastic collision between the laser beam and the atoms from the plasma discharge.The morphology and surface properties of the obtained thin films differ between these two methods.While the amorphous character is dominant for TVA thin films,enabling a smooth surface,the LTVA method produces rough surfaces with prominent crystallinity,less hydrophobic character and lower surface energy.The smooth surfaces obtained by the TVA methods produce metallic electrodes with good electrical contact,ensuring better diodes and battery charge transport.Both methods allow uniform magnesium alloys to be obtained,but the laser used in the LTVA on the discharge plasma controls the added metal or element ratio.
文摘The Theory of General Singularity is presented, unifying quantum field theory, general relativity, and the standard model. This theory posits phonons as fundamental excitations in a quantum vacuum, modeled as a Bose-Einstein condensate. Through key equations, the role of phonons as intermediaries between matter, energy, and spacetime geometry is demonstrated. The theory expands Einsteins field equations to differentiate between visible and dark matter, and revises the standard model by incorporating phonons. It addresses dark matter, dark energy, gravity, and phase transitions, while making testable predictions. The theory proposes that singularities, the essence of particles and black holes, are quantum entities ubiquitous in nature, constituting the very essence of elementary particles, seen as micro black holes or quantum fractal structures of spacetime. As the theory is refined with increasing mathematical rigor, it builds upon the foundation of initial physical intuition, connecting the spacetime continuum of general relativity with the hydrodynamics of the quantum vacuum. Inspired by the insights of Tesla and Majorana, who believed that physical intuition justifies the infringement of mathematical rigor in the early stages of theory development, this work aims to advance the understanding of the fundamental laws of the universe and the perception of reality.
基金the National Natural Science Foundation of China(No.51865012)the Natural Science Foundation of Jiangxi Province,China(No.20202BABL204040)+3 种基金the Open Foundation of National Engineering Research Center of Near-net-shape Forming for Metallic Materials,China(No.2016005)the Science Foundation of Educational Department of Jiangxi Province,China(No.GJJ170372)the GF Basic Scientific Research Project,China(No.JCKY2020205C002)the Civil Population Supporting Planning and Development Project,China(No.JPPT125GH038).
文摘A novel micro-nano Ti−10Cu−10Ni−8Al−8Nb−4Zr−1.5Hf filler was used to vacuum braze Ti−47Al−2Nb−2Cr−0.15B alloy at 1160−1220℃ for 30 min.The interfacial microstructure and formation mechanism of TiAl joints and the relationships among brazing temperature,interfacial microstructure and joint strength were emphatically investigated.Results show that the TiAl joints brazed at 1160 and 1180℃ possess three interfacial layers and mainly consist of α_(2)-Ti_(3)Al,τ_(3)-Al_(3)NiTi_(2) and Ti_(2)Ni,but the brazing seams are no longer layered and Ti_(2)Ni is completely replaced by the uniformly distributed τ_(3)-Al_(3)NiTi_(2) at 1200 and 1220℃ due to the destruction of α_(2)-Ti_(3)Al barrier layer.This transformation at 1200℃ obviously improves the tensile strength of the joint and obtains a maximum of 343 MPa.Notably,the outward diffusion of Al atoms from the dissolution of TiAl substrate dominates the microstructure evolution and tensile strength of the TiAl joint at different brazing temperatures.
基金supported by the Research Grants Council of Hong Kong Special Administrative Region Government of China(Grant Nos.15210322 and R5037-18)the financial support(Grant No.86902-00000240)from Shenzhen University.
文摘The vacuum-assisted prefabricated horizontal drain offers a promising method for strengthening soil slurry,allowing simultaneous filling and vacuum-dewatering via staged construction.However,there is limited research on the unique characteristics of staged filling.This study aims to investigate the vacuum consolidation process of staged-filled soil slurry through laboratory model tests and numerical simulations,also assessing the impact of anionic polyacrylamide.Comparative analyses are conducted between vacuum consolidation with and without anionic polyacrylamide,as well as self-weight consolidation without anionic polyacrylamide.Results reveal contour lines of excess pore pressure,water content,and soil strength forming an ellipse around the prefabricated horizontal drain board.During the consolidation process,a higher degree of consolidation,lower water content,and higher soil strength were observed closer to the prefabricated horizontal drain board.After treatment,the uppermost filling layer exhibits an average water content that was approximately 40%higher than the lower filling layer,and its average strength was about 60%lower.This discrepancy is primarily due to the absence of sealing on the top surface and the relatively short vacuum consolidation time caused by staged filling.The introduction of anionic polyacrylamide-induced flocculation significantly improves the initial consolidation rate but minimally affects the dewatering capacity of vacuum preloading.Using flocculant can enhance both the staged filling rate and soil strength(by 1e2 times).Additionally,employing a staggered arrangement between different prefabricated horizontal drain layers is advisable to prevent top-down penetration in areas with low soil strength.
基金supported by the National Magnetic Confinement Fusion Science Program of China(Nos.2022YFE03100004 and 2022YFE03060003)National Natural Science Foundation of China(Nos.12375226,12175227 and 11875255)the China Postdoctoral Science Foundation(No.2022M723066).
文摘The trajectory of the compact torus(CT)within a tokamak discharge is crucial to fueling.In this study,we developed a penetration model with a vacuum magnetic field region to accurately determine CT trajectories in tokamak discharges.This model was used to calculate the trajectory and penetration parameters of CT injections by applying both perpendicular and tangential injection schemes in both HL-2A and ITER tokamaks.For perpendicular injection along the tokamak's major radius direction from the outboard,CTs with the same injection parameters exhibited a 0.08 reduction in relative penetration depth when injected into HL-2A and a 0.13reduction when injected into ITER geometry when considering the vacuum magnetic field region compared with cases where this region was not considered.In addition,we proposed an optimization method for determining the CT's initial injection velocity to accurately calculate the initial injection velocity of CTs for central fueling in tokamaks.Furthermore,this paper discusses schemes for the tangential injection of CT into tokamak discharges.The optimal injection angle and CT magnetic moment direction for injection into both HL-2A and ITER were determined through numerical simulations.Finally,the kinetic energy loss occurring when the CT penetrated the vacuum magnetic field region in ITER was reduced byΔEk=975.08 J by optimizing the injection angle for the CT injected into ITER.These results provide valuable insights for optimizing injection angles in fusion experiments.Our model closely represents actual experimental scenarios and can assist the design of CT parameters.
文摘The development of advanced aircraft relies on high performance thermal-structural materials,and carbon/carbon com-posites(C/C)composited with ultrahigh-temperature ceramics are ideal candidates.However,the traditional routes of compositing are either inefficient and expensive or lead to a non-uniform distribution of ceramics in the matrix.Compared with the traditional C/C-ZrC-SiC composites prepared by the reactive melt infiltration of ZrSi_(2),C/C-ZrB_(2)-ZrC-SiC composites prepared by the vacuum infiltration of ZrB_(2) combined with reactive melt infiltration have the higher content and more uniform distribution of the introduced ceramic phases.The mass and linear ablation rates of the C/C-ZrB_(2)-ZrC-SiC composites were respectively 68.9%and 29.7%lower than those of C/C-ZrC-SiC composites prepared by reactive melt infiltration.The ablation performance was improved because the volatilization of B_(2)O_(3),removes some of the heat,and the more uniformly distributed ZrO_(2),that helps produce a ZrO2-SiO2 continu-ous protective layer,hinders oxygen infiltration and decreases ablation.
