Low-pressure pneumoperitoneum with abdominal wall lift in laparoscopic total mesorectal excision for rectal cancer:initial experience

AIM To evaluate the safety and feasibility of a new technology combining low-pressure pneumoperitoneum(LPP) and abdominal wall lift(AWL) in laparoscopic total mesorectal excision(TME) for rectal cancer.METHODS From November 2015 to July 2017,26 patients underwent laparoscopic TME for rectal cancer using LPP(6-8 mm Hg) with subcutaneous AWL in Qilu Hospital of Shandong University,Jinan,China.Clinical data regarding patients' demographics,intraoperative monitoring indices,operation-related indices andpathological outcomes were prospectively collected.RESULTS Laparoscopic TME was performed in 26 cases(14 anterior resection and 12 abdominoperineal resection) successfully,without conversion to open or laparoscopic surgery with standard-pressure pneumoperitoneum.Intraoperative monitoring showed stable heart rate,blood pressure and paw airway pressure.The mean operative time was 194.29 ± 41.27 min(range:125-270 min) and 200.41 ± 20.56 min(range:170-230 min) for anterior resection and abdominoperineal resection,respectively.The mean number of lymph nodes harvested was 16.71 ± 5.06(range:7-27).There was no positive circumferential or distal resection margin.No local recurrence was observed during a median follow-up period of 11.96 ± 5.55 mo(range:5-23 mo).CONCLUSION LPP combined with AWL is safe and feasible for laparoscopic TME.The technique can provide satisfactory exposure of the operative field and stable operative monitoring indices.

Process Optimization for AZ91 Mg-alloy Low-pressure EPC Process

The influence of a key process variable on the mold filling characteristics of AZ91 Mg-alloy was studied in the low pressure EPC process.The applied flow quantity of insert gas from 1 to 5 m~3/h associated with the pressurizing rate in the low pressure EPC casting process was considered for rectangle and L-shape plate casting. The experimental results show that there is an optimal flow quantity of insert gas for good mold filling characteristics in AZ91 Mg-alloy low-pressure EPC process. The optimal flow quantity of insert gas for the specimens is 3 to 4 m~3/h. Either less or higher than the optimal flow quantity of insert gas would lead to misrun defects or folds, blisters and porosity defects. The practice of hub casting confirmed that the low-pressure EPC process with an optimal processing variable exemplified as 4 m~3/h gas flow quantity was capable of producing complicated magnesium castings without misrun defects.

Numerical simulation and analysis of lithium plasma during low-pressure DC arc discharge

Alkali metal DC arc discharge has the characteristics of easy ionization,low power consumption,high plasma temperature and ionization degree,etc,which can be applied in aerospace vehicles in various ways.In this paper,we calculate the physical property parameters of lithium vapor,one of the major alkali metals,and analyze the discharge characteristics of lithium plasma with the magnetohydrodynamic(MHD)model.The discharge effects between constant current and voltage sources are also compared.It is shown that the lithium plasma of DC arc discharge has relatively high temperature and current density.The peak temperature can reach tens of thousands of K,and the current density reaches 6 x 107 A m 2.Under the same rated power,the plasma parameters of the constant voltage source discharge are much higher than those of the constant current source discharge,which can be used as the preferred discharge mode for aerospace applications.

An Experimental and Numerical Study on the Cleaning of Pleated Bag Filters Using Low-Pressure Pulsed-Jets

Pulsed-jet cleaning is recognized as the most efficient method to regenerate bag dust collectors traditionally used in industrial processes to control the emission of particulates.In this study,non-woven needle felt filter bags with and without a film coating material have been analyzed considering different geometries(different number N of pairs of pleated filter bag sides)in the frame of dedicated low-pressure pulsed-jet cleaning experiments.The flow structure inside the bag and the response characteristics of its wall have also been analyzed numerically through a computational fluid-dynamics/structural-dynamics(CFD-CSD)unidirectional fluid-solid coupling method.As shown by the experiments,the peak pressure(P_(0))on the wall of the filter bag with N=8 and 12 is higher,which indicates dust can be removed more effectively in these cases.The peak pressure on the wall increases first and then decreases along the direction of the bag length,while the peak pressure of the pleated filter bag with nonwoven needled felt film coating is greater than that without film coating.A comprehensive analysis of the time variation of acceleration,deformation,strain,stress and other factors,has led to the conclusion that the pleated filter bag with N=12 would be the optimal choice.

The mechanism study of low-pressure air plasma cleaning on large-aperture optical surface unraveled by experiment and reactive molecular dynamics simulation

Low-pressure air plasma cleaning is an effective method for removing organic contaminants on large-aperture optical components in situ in the inertial confinement fusion facility.Chemical reactions play a significant role in plasma cleaning,which is a complex process involving abundant bond cleavage and species generation.In this work,experiments and reactive molecular dynamics simulations were carried out to unravel the reaction mechanism between the benchmark organic contaminants of dibutyl phthalate and air plasma.The optical emission spectroscopy was used to study the overall evolution behaviors of excited molecular species and radical signals from air plasma as a reference to simulations.Detailed reaction pathways were revealed and characterized,and specific intermediate radicals and products were analyzed during experiments and simulation.The reactive species in the air plasma,such as O,HO_(2)and O_(3)radicals,played a crucial role in cleaving organic molecular structures.Together,our findings provide an atomic-level understanding of complex reaction processes of low-pressure air plasma cleaning mechanisms and are essential for its application in industrial plasma cleaning.

A LOW-PRESSURE AND ONE-STEP METHOD FOR THE SYNTHESIS OF ALKYLIDYNETRICOBALT NONACARBONYL CLUSTERS:RCCo_8(CO)_9

Metal clusters RCCo_3(CO)_9(R-H,C1,Br,CH_3,Ph) were prepared in 18.8-57.3% yields from the reaction of cobalt(Ⅱ)salt and RCX_a under mild PTC conditions(latm CO,25℃).The cobalt salt was reduced to Co(CO)_4 in the presence of Na_3S_2O_4.

Neutrons in a nanosecond low-pressure discharge in deuterium

Stable neutron generation with a yield of ~1.2×10^(4) neutrons per pulse was obtained during d(d,n)^(3)He reaction initiated by the high-voltage nanosecond discharge in a gap with a potential tungsten cylinder(anode)and a grounded deuterated zirconium plate(cathode)filled with deuterium at a pressure of ~10^(2) Pa.Estimated duration of the neutron pulse was ~1.5 ns.Less intensive neutron emission was registered without deuterated plate.Splashing of material of the tungsten electrode was observed during the high-voltage nanosecond discharge in the deuterium,hydrogen,helium and argon at pressures of 10^(2)-10^(4) Pa.

Microstructure and Properties of Low-pressure Cold Sprayed Al-based Composite Coatings on Magnesium Alloy Surface

Pure Al and Al-30%Al_(2)O_(3)composite coatings are prepared on the surface of AZ31B magnesium alloy by low-pressure cold spraying.The morphology and structure of the coatings are analyzed by scanning electron microscope (SEM),energy dispersive spectroscopy (EDS),and X-ray diffraction (XRD),and the effects of the addition of Al_(2)O_(3)on the microstructure of the Al-based coatings are discussed.The mechanical properties and corrosion resistance of the coatings are fully evaluated by the micro-hardness tester,electronic tensile machine,and electrochemical workstation.The results show that the coating structure is more uniform and denser,and the porosity is significantly reduced after the addition of Al_(2)O_(3).The interfaces between the coatings and the magnesium alloy substrate are distinct,and the coatings and the substrate are mechanically combined.Compared with the pure Al coating,the microhardness of the Al-Al_(2)O_(3)composite coating is increased to 61.1 HV_(0.2),and the bonding strength reaches above 53.1 MPa.The self-corrosion potential of the two coatings is higher than that of the magnesium alloy,and the self-corrosion current density is significantly lower than that of the magnesium alloy substrate.The Al-based coatings prepared by low-pressure cold spraying have high hardness,good bonding strength,and good corrosion resistance,which can be used for the repair and protection of magnesium alloy structural parts.

Simulation of propagation of the HPM in the low-pressure argon plasma

The propagation of the high-power microwave（HPM） with a frequency of 6 GHz in the lowpressure argon plasma was studied by the method of fluid approximation.The two-dimensional transmission model was built based on the wave equation,the electron drift-diffusion equations and the heavy species transport equations,which were solved by means of COMSOL Multiphysics software.The simulation results showed that the propagation characteristic of the HPM was closely related to the average electron density of the plasma.The attenuation of the transmitted wave increased nonlinearly with the electron density.Specifically,the growth of the attenuation slowed down as the electron density increased uniformly.In addition,the concrete transmission process of the HPM wave in the low-pressure argon plasma was given.

Controlling secondary flow in high-lift low-pressure turbine using boundary-layer slot suction

The design of high-lift Low-Pressure Turbines(LPTs)causes the separation of the boundary layer on the suction side of the blade and leads to a strong secondary flow.This present study aims to minimize secondary losses through endwall slot suction and incoming wakes in a front-loaded high-lift LPT cascade with Zweifel of 1.58 under low Reynolds number of 25000.Two slotted schemes for the boundary layer of the endwall were designed(Plan A and Plan B),and the effects of suction mass flow on secondary flow were studied.The underlying physics of the endwall boundary layer of the suction and secondary flow under unsteady wakes was discussed.The results show that slot suction at the endwall boundary layer can significantly suppress the secondary flow by removing low-momentum fluids.Plans A and B significantly reduced the secondary kinetic energy by 44.2%and 36.9%,respectively,compared with the baseline cascade at the suction mass flow ratios of 1%.With an increase in the mass flow ratio of suction,the secondary flow was gradually reduced in both Plans A and B.It is more beneficial to control the secondary flow to destroy the intersection of the pressure side and suction side of the horseshoe vortex before it develops into a passage vortex.Under unsteady wakes,the combined effects of incoming wakes and endwall boundary layer suction can further suppress the secondary flow at the suction mass flow ratios of 2%for Plan A,because the positive and negative vorticity inside upstream wakes accelerated the mixing of the main flow and secondary flow and thus increased the energy of secondary vortices.

Characteristics and mathematical models of the thin-layer drying of paddy rice with low-pressure superheated steam

Drying paddy with low-pressure superheated steam(LPSS)can effectively increase theγ-aminobutyric acid content in paddy.This study aimed to investigate the characteristics and mathematical models(MMs)of thin-layer drying of paddy with LPSS.The experimentally obtained data werefitted by nonlinear regression with 5 MMs commonly used for thin-layer drying to calculate the goodness of fit of the MMs.Then,the thin-layer drying of paddy with LPSS was modeled with two machine learning methods as a Bayesian regularization back propagation(BRBP)neural network and a support vector machine(SVM).The results showed that paddy drying with LPSS is a reduced-rate drying process.The drying temperature and operating pressure have a significant impact on the drying process.Under the same pressure,increasing the drying temperature can accelerate the drying rate.Under the same temperature,increasing the operating pressure can accelerate the drying rate.The comparison of the model evaluation indexes showed that 5 common empirical MMs(Hederson and Pabis,Page,Midilli,Logarithmic,and Lewis)for thin-layer drying can achieve excellent fitting effects for a single experimental condition.However,the regression fitting of the indexes by calculating the coefficient(s)of each model showed that the empirical MMs produce poor fitting effects.The BRBP neural network-based model was slightly better than the SVM-based model,and both were significantly better than the empirical MM(the Henderson and Pabis model),as evidenced by a comparison of the training root mean square error(RMSE),testing RMSE,training mean absolute error(MAE),testing MAE,training R2,and testing R2 of the Henderson and Pabis model,the BRBP neural network model,and the SVM-based model.This results indicate that the MMs established by the two machine learning methods can better predict the moisture content changes in the paddy samples dried by LPSS.

Effects of Low-pressure Annealing on the Performance of 3D Printed CF/PEEK Composites

The interlayer bonding properties are normally unsatisfying for 3D printed composites owing to the layer-by-layer formation process.In this study,low-pressure annealing was performed on 3D printed carbon fiber reinforced polyether ether ketone(CF/PEEK)to improve the interlayer bonding strength.The effects of annealing parameters on the mechanical properties and microstructure were studied.The results showed that the interlaminar shear strength(ILSS)of CF/PEEK improved by up to 55.4%after annealing.SEM and𝜇-CT were also applied to reveal the reinforcing mechanism.This improvement could mainly be attributed to the increased crystallinity of the CF/PEEK after annealing.Additionally,annealing reduced the porosity of the printed CF/PEEK and improved the fiber-resin interface.This resulted in a reduction in the stress concentration areas during loading,thereby enhancing the interlayer bonding strength of CF/PEEK.

Optimizing the low-pressure carburizing process of 16Cr3NiWMoVNbE gear steel

Compared with the traditional atm ospheric carburization, low-pressure carburization has the benefits of producing no surface oxidation and leaving fine, uniformly dispersed carbides in the carburized layer. However, the process param eters for low-pressure carburization of 16Cr3NiWMoVNbE steel have yet to be optimized. Thus, we use the saturation-value method to optimize these parameters for aviation-gear materials. Toward this end, the m icrostructure and properties of 16Cr3NiWMoVNbE steel after different carburization processes are studied by optical microscopy, scanning electron microscopy, transm ission electron microscopy, and electron probe microanalysis. Considering the saturated austenite carbon concentration, we propose a model of carbon flux and an alloy coefficient for low -pressure carburization to reduce the carbon concentration in austenite and avoid the surface carbide network. At the early stage of carburization (30 s), the gas-solid interface has a higher concentration gradient. The averaging method is not ideal in practical applications, but the carbon flux measured by using the segm ented average m ethod is 2.5 times that measured by the overall average method, which is ideal in practical applications. The corresponding carburization tim e is reduced by 60%. By using the integral average method, the actual carburization time increases, which leads to the rapid form ation of carbide on the surface and affects the entire carburization process. Nb and Wcombine with C to form carbides, which hinders carbon diffusion and consumes carbon, resulting in a sharp decrease in the rate of C diffusion in austenite (the diffusion rate is reduced by 52% for 16Cr3NiWMoVNbE steel). By changing the diffusion coefficient model and comparing the hardness gradient of different processes, the depth of the actual layer is found to be very similar to the design depth.

Unsteady wakes-secondary flow interactions in a high-lift low-pressure turbine cascade

Detailed experimental measurements were conducted to study the interactions between incoming wakes and endwall secondary flow in a high-lift Low-Pressure Turbine(LPT)cascade.All of the measurements were conducted in both the presence and absence of incoming wakes,and numerical analysis was performed to elucidate the flow mechanism.With increasing Reynolds number,the influence of the incoming wakes on suppressing the secondary flow gradually increased owing to the greater influence of incoming wakes on reducing the negative incidence angle at higher Reynolds numbers,leading to a lower blade loading near the leading edge and suppression of the Pressure Side(PS)leg of the horseshoe vortex.However,the effect of unsteady wakes on suppressing the profile losses gradually became weaker owing to the reduced size of the Suction Side(SS)separation bubble and increased mixing loss in the free-flow region at high Reynolds numbers.Incoming wakes clearly improved the aerodynamic performance of the low-pressure turbine cascade at low Reynolds numbers of 25,000 and 50,000.In contrast,at the high Reynolds number of 100,000,the profile loss at the midspan and mass-averaged total losses downstream of the cascade were higher in the presence of wakes than in the absence of wakes,and the unsteady wakes exerted a negative influence on the aerodynamic performance of the LPT cascade.

Development of a new high-shear and low-pressure grinding wheel and its grinding characteristics for Inconel718 alloy

Nickel-based alloy has been widely used due to its outstanding mechanical properties.However, Nickel-based alloy is a typical difficult-to-machine material, which is a great constrain for its application in the manufacturing field. To improve the surface quality of the ground workpiece, a new high-shear and low-pressure grinding wheel, with high ratio of tangential grinding force to normal grinding force, was fabricated for the grinding of selective laser melting(SLM) manufactured Inconel718 alloy. The principle of high-shear and low-pressure grinding process was introduced in detail, which was quite different from the conventional grinding process. The fabrication process of the new grinding wheel was illustrated. A serial of experiments with different processing parameters were carried out to investigate the grinding performance of the developed grinding wheel via analyzing surface roughness and surface morphology of the ground workpiece.The optimal processing parameters of high-shear and low-pressure grinding were obtained. The surface roughness of ground workpiece was reduced to 0.232 μm from the initial value of 0.490 μm under the optimal grinding conditions. It was found that the initial scratches on the ground workpiece were almost completely removed after the observations with the metalloscopy and the fieldemission scanning electron microscopy(FE-SEM). The capability of the newly developed highshear and low-pressure grinding wheel was validated.

Non-equilibrium phase diagram of stationary states for low-pressure diamond growth

Now, it is well known that stable diamond growth and etching of graphite can berealized simultaneously under low pressures, but it is difficult to explain by classicalthermodynamics.Based on the non-equilibrium thermodynamic coupling theorem. low-pressure diamondgrowth can be explained clearly as follows:The change of Gibbs free energy (G) is the criterion of reaction direction at constant tem-perature and pressure. Therefore,

A projective ternary phase diagram of stationary non-equilibrium states for low-pressure diamond growth

SINCE 1980,activated low-pressure diamond growth by chemical vapor deposition(CVD)pro-cess has been one of the worldwide interesting projects.However,in the last decades severalthermodynamic explanations were unsatisfactory.Bachmann et al.summarized a lot ofpublished experimental data into an empirical ternary carbon-hydrogen-oxygen(C-H-O)

LPCS Ni-Zn-Al_(2)O_(3) Intermediate Layer Enhanced SPS NiCr-Cr_(3)C_(2) Coating with Higher Corrosion and Wear Resistances

The double-layer NiCr-Cr_(3)C_(2)/Ni-Zn-Al_(2)O_(3) coatings with sufficient corrosion and wear resistance were prepared on low carbon steel substrates.The intermediate layers Ni-Zn-Al_(2)O_(3) were fabricated by using low-pressure cold spray (LPCS) method to improve the salt fog corrosion resistance properties of the supersonic plasma spray (SPS) NiCr-Cr_(3)C_(2) coatings.The friction and wear performance for the double-layer and single-layer NiCr-Cr_(3)C_(2) coatings were carried out by line-contact reciprocating sliding,respectively.Combined with the coating surface analysis techniques,the effect of the salt fog corrosion on the tribological properties of the double-layer coatings was studied.The results showed that the double-layer coatings exhibited better wear resistance than that of the single-layer coatings,due to the better corrosion resistance of the intermediate layer;the wear mass losses of the double-layer coatings was reduced by 70%than that of the single layer coatings and the wear mechanism of coatings after salt fog corrosion conditions is mainly corrosion wear.

Analysis of the Heavy Rainfall Process in Mangshi City on August 8, 2023

On August 7,2023,Mangshi City,Dehong Prefecture experienced a local heavy rainstorm,and the geological disaster caused by the heavy rainfall caused casualties and property losses.Based on the real-time observation data of automatic stations,Doppler weather radar detection and meteorological risk warning products,the disaster situation,social impact,forecast and early warning service,causes of heavy precipitation and forecast and early warning inspection were summarized and analyzed.The results show that the heavy rainfall was prominent locally,lasted for a long time and accumulated a large amount of rainfall.There were biases in model products,and it was difficult for forecasters to make subjective corrections in complex terrain.The analysis ideas and focus points of heavy rainfall forecast,the improvement ideas and technical schemes of forecast deviation,and the improvement ideas and suggestions of services were summarized.It provides a reference for the forecast and early warning of severe weather in the future.

Theoretical analyses on the one-dimensional charged particle transport in a decaying plasma under an electrostatic field

The spatiotemporal evolutions of a one-dimensional collisionless decaying plasma bounded by two electrodes with an externally applied electrostatic field are studied by theoretical analyses and particle-in-cell(PIC)simulations with the ion extraction process in a laser-induced plasma as the major research background.Based on the theoretical analyses,the transport process of the charged particles including electrons and ions can be divided into three stages:electron oscillation and ion matrix sheath extraction stage,sheath expansion and ion rarefaction wave propagation stage and the plasma collapse stage,and the corresponding criterion for each stage is also presented.Consequently,a complete analytical model is established for describing the ion extraction flux at each stage during the decaying of the laser-induced plasmas under an electrostatic field,which is also validated by the PIC modeling results.Based on this analytical model,influences of the key physical parameters,including the initial electron temperature and number density,plasma width and the externally applied electric voltage,on the ratio of the extracted ions are predicted.The calculated results show that a higher applied electric potential,smaller initial plasma number density and plasma width lead to a higher ratio of the extracted ions during the first stage;while in this stage,the initial electron temperature shows little effect on it.Meanwhile,more ions will be extracted before the plasma collapse once a higher electric potential is applied.The theoretical model presented in this paper is helpful not only for a deep understanding to the charged particle transport mechanisms for a bounded decaying plasma under an applied electrostatic field,but also for an optimization of the ion extraction process in practical applications.