Mechanical compression management of the right middle cerebral artery inferior trunk using a stent during coil embolization of middle cerebral artery aneurysms:A case report and literature review

Endovascular coil embolization is a minimally invasive,rapid,and effective method for the treatment of intracranial aneurysms.However,complications associated with coil embolization,such as intraoperative aneurysm rupture or arterial occlusion,should be promptly managed during the procedure to avoid catastrophic consequences.This study presents a case of mechanical compression management of the right middle cerebral artery(MCA)inferior trunk during coil embolization for bilateral MCA aneurysms.The inferior trunk of the right MCA was abruptly occluded due to mechanical compression during coil embolization of the right MCA bifurcation aneurysm.A Solitaire AB stent(4×20 mm,Covidien/Medtronic,Dublin,Ireland)was implanted in the inferior trunk of the right MCA after tirofiban was injected via a microcatheter,and the right inferior trunk was recanalized.The patient also underwent coil embolization of the left MCA bifurcation aneurysm,without any complications.It is crucial to recognize compressive occlusion of adjacent aneurysm branches to avoid severe complications during intracranial aneurysm embolization.Stent placement is a rescue treatment option for recanalization of an occluded artery.

Utilization of mechanical compression as a disinfestation technique for Hessian fly(Mayetiola destructor(say))in timothy hay:Field test

Baled timothy hay underwent testing at a hay processing plant in Canada to determine if mechanical compression(rebaling)could be used as a disinfestation protocol for Hessian fly(Mayetiola destructor(Say))puparia.Pressure sensitive films were randomly placed throughout the hay material,on the chamber walls,and in different orientations,to assess the hay compaction unit’s ability to induce the required pressure to crash a Hessian fly puparium in the hay.Attached to the pressure films were organdy cages containing wheat seedlings infested with Hessian fly puparia.The variables which were tested included the hold time(0.5 and 2.0 s),applied pressure(10.34 and 12.41 MPa),and timothy hay quality(low-moisture first cut,high-moisture first cut and high-moisture second cut hay).A total of 36 tests were conducted.For each test,10 Hessian fly cages and 10 pressure sensitive films were used.Each test cage contained approximately 168.56 Hessian fly puparia,translating into a total Hessian fly count of 60681 for the entire field test.Analysis of the pressure sensitive films showed that 100%of the hay experienced at least 200 kPa(29 psi)of pressure.Following the 75-day post experiment emergence period,0.0066%of the puparia survived,which may be due to the fact that the emerged puparia might have not been crushed and not subjected to a pressure of at least 20.6 kPa.The applied pressures affected Hessian fly emergence by considerably reducing the number of puparia that emerged.However,Hessian fly emerged from one of the cages in two tests.Most of the Hessian fly puparia were destroyed irrespective of the applied pressure,hold time or hay quality.

Ion dynamics into different pore size distributions in supercapacitors under compression

Compressing supercapacitor(SCs)electrode is essential for improving the energy storage characteristics and minimizing ions’distance travel,faradaic reactions,and overall ohmic resistance.Studies comprising the ion dynamics in SC electrodes under compression are still rare.So,the ionic dynamics of five aqueous electrolytes in electrodes under compression were studied in this work for tracking electrochemical and structural changes under mechanical stress.A superionic state is formed when the electrode is compressed until the micropores match the dimensions with the electrolyte’s hydrated ion sizes,which increases the capacitance.If excessive compression is applied,the accessible pore regions decrease,and the capacitance drops.Hence,as the studied hydrated ions have different dimensions,the match between ion/pore sizes differs.To the LiOH and NaClO4electrolytes,increasing the pressure from 60 to 120 and 100 PSI raised the capacitance from 13.5 to 35.2 F g^(-1)and 30.9 to 39.0 F g^(-1),respectively.So,the KOH electrolyte with the lowest and LiCl with the biggest combination of hydrated ion size have their point of maximum capacitance(39.5 and 36.7F g^(-1))achieved at 140 and 80 PSI,respectively.To LiCl and KCl electrolytes,overcompression causes a drop in capacitance higher than 23%.

A Chest Compression Quality Evaluation Using Mechanical Chest Compressions under Different Working Situations in the Ambulance

Objectives: The aim of this study was to analyze the quality of chest compressions in different working situations pertaining to ambulance crews using either standard chest compressions (S-CC) or LUCAS mechanical chest compressions (L-CC) in a manikin setting. Participants and Methods: Cardiopulmonary resuscitation (CPR) was performed using a compression to ventilation ratio of 30:2 with both S-CC and L-CC. Quality parameters were collected using a modified manikin enabling impedance measurements. The evaluation was performed in two manikin scenarios: Scenario 1 evaluated ten minutes of CPR on the ground and Scenario 2 assessed six minutes of CPR in different settings relevant to work in the ambulance. Quality parameters compared were: time to apply LUCAS, hands-off fraction, number of correct chest compressions and the rate of compressions. Results: In Scenario 1 the hands-off fraction was higher when S-CC was performed (S-CC group 29% vs. L-CC 16%, P = 0.003). We found a higher number of chest compressions (S-CC = 913 vs. L-CC = 831, P = 0.0049) and a higher rate of chest compressions (S-CC = 118 vs. L-CC = 99, P < 0.0001) in the S-CC group. In Scenario 2 we noted a higher hands-off fraction for S-CC (39% vs. L-CC = 19%, P = 0.003), but a higher number of compressions given during S-CC ((n = 504) vs. L-CC (n = 396) P = 0.0002). Conclusion: Mechanical chest compression with the LUCAS 2TM device enables ambulance personnel to provide high quality chest compression even while transporting the patient.

Design and Analysis on Compression Mechanism of Small Square Bales of Sugarcane Leaf Baler

With more and more attention paid to comprehensive utilization of agricul-tural biomass resources, environment pol ution caused by large-scale burning of sug-arcane leaves can be effectively avoided, and it is urgent to resolve storage issue of sugarcane leaf. Through referring to the relevant domestic baler models and re-search findings, preliminary design and analysis were conducted on key components compression mechanism of smal sugarcane leaf baler, involving the open compres-sion principle for sugarcane leaf square baler, determination of the crank slider-type compression mechanism and the main parameters such as crank length, compres-sion frequency, feed rate and feed inlet length. Based on SolidWorks software, this paper established the 3-dimensional models of slider-crank type compression mech-anism, and imported it into ADMAMS software for the motion simulation analysis, to establish the foundation for the design and manufacture of subsequent smal sugar-cane leaf square baler prototype.

Mechanical cardiopulmonary resuscitation for patients with cardiac arrest

BACKGROUND：Although modern cardiopulmonary resuscitation （CPR） substantially decreases the mortality induced by cardiac arrest, cardiac arrest still accounts for over 50% of deaths caused by cardiovascular diseases. In this article, we address the current use of mechanical devices during CPR, and also compare the CPR quality between manual and mechanical chest compression. METHODS：We compared the quality and survival rate between manual and mechanical CPR, and then reviewed the mechanical CPR in special circumstance, such as percutaneous coronary intervention, transportation, and other fields. RESULTS：Compared with manual compression, mechanical compression can often be done correctly, and thus can compromise survival; can provide high quality chest compressions in a moving ambulance; enhance the flow of blood back to the heart via a rhythmic constriction of the veins; allow ventilation and CPR to be per formed simultaneously. CONCLUSION：Mechanical devices will be widely used in clinical practice so as to improve the quality of CPR in patients with cardiac arrest.

Varying of up-conversion nanoparticles luminescence from the muscle tissue depth during the compression

The current work is focused on the study of optical clearing of skeletal muscles under local compression.The experiments were performed on in vitro bovine skeletal muscle.The time dependence of optical clearing was studied by monitoring the luminescence intensity of NaYF_(4)∶Er,Yb upconverting particles located under tissue layers.This study shows the possibility to use upconverting nanoparticles(UCNPs)both for studying the dynamics of the optical clearing of biological tissue under compression and to detect moments of cell wall damage under excessive pressure.The advantage of using UCNPs is the presence of several bands in their luminescence spectra,located both at close wavelengths and far apart.

Mechanical properties of cement mortar in sodium sulfate and sodium chloride solutions

To investigate the mechanical properties of cement mortar in sodium sulfate and sodium chloride solutions, uniaxial compression test and ultrasonic test were performed. Test results show that the relative dynamic elastic modulus, the mass variation,and the compressive strength of cement mortar increase first, and then decrease with increasing erosion time in sodium sulfate and sodium chloride solutions. The relative dynamic elastic moduli and the compressive strengths of cement mortars with water/cement ratios of 0.55 and 0.65 in sodium sulfate solution are lower than those in sodium chloride solution with the same concentration at the420 th day of immersion. The compressive strength of cement mortar with water/cement ratio of 0.65 is more sensitive to strain rate than that with water/cement ratio of 0.55. In addition, the strain-rate sensitivity of compressive strength of cement mortar will increase under attacks of sodium sulfate or sodium chloride solution.

Investigate the Effect of the Magnetic Field on the Mechanical Properties of Silicone Rubber-Based Anisotropic Magnetorheological Elastomer during Curing Process

In this investigation,a new silicone rubber-based MRE material was prepared to be used as a forming medium in manufacturing thin-walled complexshaped Ni-based tubes through the bulging process.Thus,it is significant to investigate the effect of magnetic field intensity,magnetic field loading time,and angle on the mechanical properties of the prepared MRE material during the curing process.The obtained results showed that increasing the magnetic field intensity during the curing process can improve the orientation of the chain structure in the elastomer matrix effectively.However,its mechanical properties are the best under the corresponding magnetic field intensity of 321 mT.Besides,by extending the magnetic field loading time in the curing process,the orientation of the chain structure was optimized,at the same time,the mechanical properties were also improved,and the best loading time is about 20–25 min.By changing the loading angle of the magnetic field during the curing process,the mechanical properties of the MRE were improved.When the loading angle of the magnetic field is 90°,the elastomer showed the best compression mechanical properties and excellent compression reversibility.Besides,for the anisotropic MRE material,the performance with magnetic compression is always better than that without magnetic compression.

Analysis of an Evaporator-condenser-separated Mechanical Vapor Compression System

An evaporator-condenser-separated mechanical vapor compression (MVC) system was presented. The better effect of descaling and antiscaling was obtained by the new system. This study focused on the method of thermodynamic analysis, and the energy and exergy flow diagrams were established by using the first and second law of thermodynamics analysis. The results show that the energy utilization rate is very high and the specific power consumption is low. Exergy analysis indicates that the exergy efficiency is low, and the largest exergy loss occurs within the evaporator-condenser and the compressor.

Experimental investigation on the energy evolution of dry and water-saturated red sandstones

In order to investigate the effect of water content on the energy evolution of red sandstone, the axial loading–unloading experiments on dry and water-saturated sandstone samples were conducted, and the distribution and evolution of elastic energy and dissipated energy within the rock were measured.The results show that the saturation process from dry to fully-saturated states reduces the strength, rigidity and brittleness of the rock by 30.2%, 25.5% and 16.7%, respectively. The water-saturated sample has larger irreversible deformation in the pre-peak stage and smaller stress drop in the post-peak stage.The saturation process decreases the accumulation energy limit by 38.9%, but increases the dissipated energy and residual elastic energy density, thus greatly reducing the magnitude and rate of energy release. The water-saturated sample has lower conversion efficiency to elastic energy by 3% in the prepeak region; moreover, the elastic energy ratio falls with a smaller range in the post-peak stage.Therefore, saturation process can greatly reduce the risk of dynamic disaster, and heterogeneous water content can lead to dynamic disaster possibly on the other hand.

Effect of suppressing dust by multi-direction whirling air curtain on fully mechanized mining face

A combined method of numerical simulation and field testing was adopted in this study in the interest of solving the problem of hard to control high concentrate dusts on a fully mechanized mining face. In addi- tion, the dust suppression effect of a multi-direction whirling air curtain was studied in this paper. Under the influence of the wall attachment effect, the compressed air which blows out from the two-phase or three-phase radial outlets on the generator of the air curtain can form a multi-direction whirling air curtain, which can cover the whole roadway section of a fully mechanized mining face. The traditional method of controlling dust is a forcing system with exhaust overlap which has the major disadvantage of lacking a jet effect and consequently results in poor dust control. It is difficult to form the air flow field within the range of Lp ≤ 5√S. However, due to the effect of this novel system, the radial airflow can be turned into axial airflow allowing fresh air to flow through the length of the heading. The air flow field which is good at controlling dust diffusion can be formed 12.8 m from the heading face. Furthermore, the field measurement results show that before the application of a multi-direction whirling air curtain, the dust concentration is 348.6 mg/m^3 and 271.4 mg/m^3 respectively at the roadway cross-section measurement points which are 5 m and 10 m from the heading face. However, after the application of the multi-direction whirling air curtain, the dust concentration is only 61.2 mg/m3 and 14.8 mg/m^3, respectively. Therefore, the dust control effect of a multi-direction whirling air curtain is obvious.

Strain-rate Sensitivity of Aluminum 2024-T6/TiB_2 Composites and Aluminum 2024-T6

Strain-rate sensitivities of 55vol%-65vol% aluminum 2024-T6/TiB2 composites and the corresponding aluminum 2024-T6 matrix were investigated using split Hopkinson pressure bar method. The experimental results showed that 55vol%-65vol% aluminum 2024-T6/TiB2 composites exhibited significant strain-rate sensitivities, which were three times higher than the strain-rate sensitivity of the aluminum 2024-T6 matrix. The strain-rate sensitivity of the aluminum 2024-T6 matrix composites rose obviously with increasing reinforcement content（up to 60%）, which agreed with that from the previous researches. But it decreased as the ceramic reinforcement content reached 65%. After high strain rates compression, a large number of dislocations and micro-cracks were found inside the matrix and the Ti B2 particles, respectively. These micro-cracks can accelerate the brittle fracture of the composites. The aluminum 2024-T6/Ti B2 composites showed various fracture characteristics and shear instability was the predominant failure mechanism under dynamic loading.

COMPRESSIVE COMMINUTION MECHANISM OF PARTICLE BEDS

Granular material mechanics,finite element analysis and crushing theory are applied to study the compressive comminution mechanism of particle beds in this paper.This is a new method by which we have established an equivalent model of granular material,determined the values and distributions of contact forces and discovered a crushing law.The model has been tested on the newly designed equipment and proved to be correct.Some new characteristics and laws of compressive comminution of particle beds have been found.

Enhanced Strength and Ductility Due to Microstructure Refinement and Texture Weakening of the GW102K Alloy by Cyclic Extrusion Compression

The cyclic extrusion compression （CEC） was applied to severely deform the as-extruded GW102K （Mg- 10.0Gd-2.0Y-0.5Zr, wt%） alloy at 350, 400, and 450 ℃, respectively. The microstructure, texture, and grain boundary character distribution of the CECed alloy were investigated in the present work. The mechan- ical properties were measured by uniaxial tension at room temperature. The crack initiation on the longitudinal section near the tensile fracture-surface was investigated by high-resolution scanning elec- tron microscopy （SEM）. The result shows that the microstructure was dramatically refined by dynamic recrystallization （DRX）. The initial fiber texture was disintegrated and obviously weakened. The 8-passes/ 350 ℃ CECed alloy exhibited yield strength of 318 MPa with an elongation-to-fracture of 16.8%, increased by 41.3% and 162.5%, respectively. Moreover, the elongation-to-fracture of the 8-passes/450 ℃ CECed alloy significantly increased more than 3 times than that of the received alloy. The cracks were mainly initi- ated at twin boundaries and second phase/matrix interfaces during tensile deformation. The microstructure refinement was considered to result in the dramatically enhanced of the strength and ductility. In ad- dition, the texture randomization during CEC is beneficial for enhancing ductility. The standard positive Hall-Petch relationships have been obtained for the CECed GW102K alloy.