Crack-free high-aspect ratio holes in glasses by top–down percussion drilling with infrared femtosecond laser GHz-bursts

We report novel results on top-down percussion drilling in different glasses with femtosecond laser GHz-bursts.Thanks to this particular regime of light–matter interaction,combining non-linear absorption and thermal cumulative effects,we obtained crack-free holes of aspect ratios exceeding 30 in sodalime and 70 in fused silica.The results are discussed in terms of inner wall morphology,aspect ratio and drilling speed.

Capacitor discharge percussion welding of pure aluminum wire to pure copper sheet

This paper presents the results of a research into capacitor discharge percussion welding （CDPW） of pure aluminum wires and pure copper sheets, using percussion welding power and special welding device. A lot of CDPW factors, which will affect aluminum and copper dissimilar bonding, are described and these parameters have also been optimized. The fracture pull, interface compounds, microstructure and hardness are all studied. The results show that aluminum wire welding to copper sheet can form a sound weld and in some conditions the fracture pull is similar to that of the pure aluminum wires. The capacitance, discharge voltage, wire taper angle and machine oil as welding assistant medium affect fracture pull. The intermetaUic compounds A12 Cu appears on the copper side of joint. Narrower heat-affected zone is observed.

Stability of rat models of fluid percussion-induced traumatic brain injury: comparison of three different impact forces

Fluid percussion-induced traumatic brain injury models have been widely used in experimental research for years. In an experiment, the stability of impaction is inevitably affected by factors such as the appearance of liquid spikes. Management of impact pressure is a crucial factor that determines the stability of these models, and direction of impact control is another basic element. To improve experimental stability, we calculated a pressure curve by generating repeated impacts using a fluid percussion device at different pendulum angles. A stereotactic frame was used to control the direction of impact. We produced stable and reproducible models, including mild, moderate, and severe traumatic brain injury, using the MODEL01-B device at pendulum angles of 6°, 11° and 13°, with corresponding impact force values of 1.0 ± 0.11 atm（101.32 ± 11.16 k Pa）, 2.6 ± 0.16 atm（263.44 ± 16.21 k Pa）, and 3.6 ± 0.16 atm（364.77 ± 16.21 k Pa）, respectively. Behavioral tests, hematoxylin-eosin staining, and magnetic resonance imaging revealed that models for different degrees of injury were consistent with the clinical properties of mild, moderate, and severe craniocerebral injuries. Using this method, we established fluid percussion models for different degrees of injury and stabilized pathological features based on precise power and direction control.

Study on the Mechanism of Fluid Percussion Injuries on Immune Cells

Background Traffic accidents,anti-terrorism,gas and chemical dangerous goods explosions,earthquake shock wave damage,and falling impacts in daily life and other events involving impact loads cause great harm to human organs and tissues,and even life-threatening.Such injuries are called impact damage.Although during the previous wars,the treatment of impact injuries has been greatly improved,and its treatment has been widely used in clinical practice.However,under the current development of society,the impact damage incident has not only been limited to the battlefield.Extreme organizations,frequent industrial production accidents,aircraft trains and other accidents have extended the impact damage incidents into daily society,seriously jeopardizing the health of civilians.Therefore,in order to better treat the injured organs under the impact load,such as the reconstruction and recovery of organ tissues,it is necessary to establish a corresponding system of clinical treatment methods for impact damage.In vitro models of traumatic injury are helping elucidate the pathobiological mechanisms responsible for dysfunction and delayed cell functional variation after mechanical stimulation of the single waveform pressure.It is likely that injury outcome is related to the biomechanical parameters of the traumatic event such as amplitudes and durations.However,the influence of impulsive pressure on endothelial function has not yet been fully studied in vitro.In this study,we developed a pressure loading device that produced positive by modifying an in vitro fluid percussion model and examined the effects of the pressures on macrophages’basic functions.Methods To model variations in the biomechanical injury parameters and simplify the experiment,single-use syringe was chosen to be the cell container and a drop hammer driven fluid percussion injury system(FPI)was designed and built to generate a single waveform with adjustable peak pressure and durations.Mice macrophage cells(Raw 264.7)were subjected to three types of the single positive pressure(120 kPa,550 kPa and 1 100 kPa).Every 12 hours we detected its basic functions(including phagocytosis and proliferative capacity)during the following 48 hours,also the immediate cell death.Results This single waveform pressure loading device could produce positive pressure with amplitudes of 70~1 200 kPa.After the pressure loading,there is no significant differences between the control cells and experiment cells.However,it does have a notable effect on its basic functions.The results showed that its phagocytosis and proliferative capacity were getting increased with a peak value on36 h and suddenly decreasing on 48 h.Moreover,these 4 regular curves are in proportion to the pressure.And the experimental results also indicate that the cell impact platform can achieve a single impact loading on the cells.The impact mainly causes the functional changes of RAW264.7 cells instead of directly causing its death.The cell proliferation activity and phagocytosis function are enhanced to some extent.Conclusions Those results indicate that single waveform pressure have a main effect on cell’s biological functions,not on cell death.And these effects on functions did have a regular functional rela-tionship.To explore more regular curves and the mechanism,we need more experiments such as genomics technical.

Acoustic Performance of Green Composites for Chinese Traditional Percussion Drums

Flax and jute fabrics are adopted to reinforce epoxy matrix composites in order to explore the feasibility of replacing wood in percussion instruments.The fabrics are treated with alkaline solutions to improve interfacial adhesion between fibers and epoxy.The composites are fabricated using the hand-lay and vacuum assisted resin infusion process.Acoustic dynamic moduli,acoustic radiation damping coefficients,and acoustic impedances of the composites are tested and compared with those of the wood regularly used to make the percussion instruments.It is found that the acoustic properties of the composites are within the range of those of the wood,indicating that it could be feasible to replace the wood with natural cellulose fiber reinforced composites in percussion instrument production.

THREE DIMENSIONAL DYNAMIC ELASTICPLASTIC ANALYSIS OF THE INTERACTION OF A SET OF PERCUSSION BITS WITH ROCK MASSES

A three dimensional dynamic elastic-plastic finite element analysis of the interaction of percussion bits with rock masses is presented. The dynamic contact problem was investigated with the numerical method developed for high velocity impact calculations[1]. The numerical analysis was carried out for three simultaneously loaded percussion bits arranged on a straight line on the rock surface, the loading time was kept constant throughout this work. The numerical calculation for various strengths of the dynamic load tm the percussion bits shows that a critical minimum dynamic load exists for the generation of plastic deformations in the rock. For this critical value of the load the maximum normal stress of the longitudinal wave in the percussion bit exceeds the yield stress of the rock mass.

Effects of Latin,Rock and African Percussion Music on Protein and Energy Metabolism in Cow

This study was conducted to study the effects of Latin,rock,and African percussion music on milk production performance in cow. 72 Holstein cows with similar milk yield,age,parity and lactation were randomly divided into four groups,namely the Latin music group,rock music group,African percussion music group and control group,each 18 cows. The pretrial period lasted for 7 d,and the formal trial period was 60 d. The music began to be played in test group from pretrial period,while the control group received routine feeding. Milk yield was measured every 20 d,and milk sample was collected once. The results showed that African percussion music could increase the contents of GLB,ALT and LDH in the serum of cow,and reduce the milk yield of cow. Rock music would increase the serum LDH content in cow and reduce the milk yield of cow.

KANE’S EQUATIONS FOR PERCUSSION MOTION OF VARIABLE MASS NONHOLONOMIC MECHANICAL SYSTEMS

In this paper,the Kane’s equations for the Routh’s form of variable massnonholonomic systems are established.and the Kane’s equations for percussion motionof variable mass holonomic and nonholonomic systems are deduced from them. Secondly,the equivalence to Lagrange’s equations for percussion motion and Kane’sequations is obtained,and the application of the new equation is illustrated by anexample.

New Properties of HM16 Ether, with Submicroparticles as Self-Functional Cells Interacting through Percussion Forces, Establishing Nature of Electrical Charges, including Gravitation

Article continues and complements our previous articles on the HM16 ether (ETH) model. Here, we describe the mechanism of occurrence of the submicroparticle (SMP). A general hypothesis, HFVI, is introduced for the modalities of interaction between two SMPs, based on periodic mechanical percussion forces, produced by fundamental vibrations FVs. A mechanism for describing the interaction between a SMPs and the ETH is presented. Positive and negative particles are defined by their membrane types of movement, such as +, −u/+, −v vibrations, and rotations at speeds +Ω/−Ω. The process of creating a pair of SMPs is discussed. Applying HFVI to the interaction between pairs of SMPs immobile in ETH, and considering longitudinal FVL, was obtained the forces of attraction/repulsion +FL21/–FL21, which correspond to the completed Coulomb force FCC including gravitation. The resultant FRL21 will form an oriented field of forces, which is a quasielectric field QE, equivalent to actual E electric field. Considering transversal FVT, was obtained the vibratory forces +, −FT21, whose resultant forms an vibrating field of forces, QHs, a quasimagnetic special field, which may explain some of the quantum properties of SMPs. Considering a mobile SMP, two new γ strains in ETH appear. Strains γL are created by the displacement of SMP with velocity V, whose force +, −FT12 is the support of a component of the magnetic field H (quasimagnetic field QH), giving the QHL component. Strains γR are created by the rotation of SMP with speed Ω, whose force +, −FR12 constitutes physical support of the component QHR of magnetic field H (i.e. QH). The creation of a photon PH is modelled as a special ESMP containing two zones of opposed rotations, and a mechanism is presented for its movement in the ETH with speed c based on the HS hypothesis of screwing in ETH, with frequency ν.

Experimental studies on rock failure mechanisms under impact load by single polycrystalline diamond compact cutter

Percussive drilling shows excellent potential for promoting the rate of penetration(ROP)in drilling hard formations.Polycrystalline diamond compact(PDC)bits account for most of the footage drilled in the oil and gas fields.To reveal the rock failure mechanisms under the impact load by PDC bits,a series of drop tests with a single PDC cutter were conducted to four kinds of rocks at different back rake angles,drop heights,drop mass,and drop times.Then the morphology characteristics of the craters were obtained and quantified by using a three-dimensional profilometer.The fracture micrographs can be observed by using scanning electron microscope(SEM).The distribution and propagation process of subsurface cracks were captured in rock-like silica glass by a high-speed photography system.The results can indicate that percussive drilling has a higher efficiency and ROP when the rock fractures in brittle mode.The failure mode of rock is related with the type of rock,the impact speed,and the back rake angle of the cutter.Both the penetration depth and fragmentation volume get the maximum values at a back rake angle of about 45°.Increasing the weight and speed of falling hammer is beneficial to improving the rock breaking effects and efficiency.The subsurface cracks under the impact load by a single PDC cutter is shaped like a clamshell,and its size is much larger than the crater volume.These findings can help to shed light on the rock failure mechanisms under the impact of load by a single PDC cutter and provide a theoretical explanation for better field application of percussive drilling.

Micro-macro fracture mechanism of heterogeneous granite in percussive drilling

The conventional rotary rock breaking method faces a technical bottleneck in improving the rate of penetration(ROP)in deep hard formations.Percussive drilling is the most potential approach to increase rock-breaking efficiency and ROP.However,the rock-breaking mechanism of percussive drilling is still unclear enough,especially the micro-fracture mechanism of rock under confining pressure(under lateral pressure and hydraulic pressure).In this paper,the impact rock breaking experiments by four kinds of Polycrystalline Diamond Compact(PDC)cutters are carried out using a drop-weight impact testing machine and an acoustic emission(AE)recording system,the influence of parameters such as cutter shape,rake angle,and impact energy on rock-breaking are systematically analyzed.This study includes a numerical simulation to examine the process of crack initiation,propagation,and cuttings formation during the impact process with the consideration of confining pressure.The results show the conicalshaped cutter is the most aggressive with high breaking efficiency.The penetration depth of the cutter is mainly influenced by the impact energy and cutter shape than the rake angle of the cutter.There exists critical impact energy makes the rock breaking efficiency the highest.The critical impact energy is about 40 J when using the conical-shaped cutter with a rake angle of 15°.The rock mainly failed in tensile mode,and the inter-grain crack is the main crack.Hydraulic pressure can inhibit the formation of horizontal cracks,while lateral pressure can inhibit the formation of vertical cracks and reduce the proportion of tensile cracks.The research results can provide some reference and basis for improving the rock-breaking efficiency in deep hard formations.

Polydatin prevents the induction of secondary brain injury after traumatic brain injury by protecting neuronal mitochondria

Polydatin is thought to protect mitochondria in different cell types in various diseases.Mitochondrial dysfunction is a major contributing factor in secondary brain injury resulting from traumatic brain injury.To investigate the protective effect of polydatin after traumatic brain injury,a rat brain injury model of lateral fluid percussion was established to mimic traumatic brain injury insults.Rat models were intraperitoneally injected with polydatin(30 mg/kg)or the SIRT1 activator SRT1720(20 mg/kg,as a positive control to polydatin).At 6 hours post-traumatic brain injury insults,western blot assay was used to detect the expression of SIRT1,endoplasmic reticulum stress related proteins and p38 phosphorylation in cerebral cortex on the injured side.Flow cytometry was used to analyze neuronal mitochondrial superoxide,mitochondrial membrane potential and mitochondrial permeability transition pore opened.Ultrastructural damage in neuronal mitochondria was measured by transmission electron microscopy.Our results showed that after treatment with polydatin,release of reactive oxygen species in neuronal mitochondria was markedly reduced;swelling of mitochondria was alleviated;mitochondrial membrane potential was maintained;mitochondrial permeability transition pore opened.Also endoplasmic reticulum stress related proteins were inhibited,including the activation of p-PERK,spliced XBP-1 and cleaved ATF6.SIRT1 expression and activity were increased;p38 phosphorylation and cleaved caspase-9/3 activation were inhibited.Neurological scores of treated rats were increased and the mortality was reduced compared with the rats only subjected to traumatic brain injury.These results indicated that polydatin protectrd rats from the consequences of traumatic brain injury and exerted a protective effect on neuronal mitochondria.The mechanisms may be linked to increased SIRT1 expression and activity,which inhibits the p38 phosphorylation-mediated mitochondrial apoptotic pathway.This study was approved by the Animal Care and Use Committee of the Southern Medical University,China(approval number:L2016113)on January 1,2016.

The pig as a preclinical traumatic brain injury model:current models,functional outcome measures,and translational detection strategies

Traumatic brain injury(TBI) is a major contributor of long-term disability and a leading cause of death worldwide. A series of secondary injury cascades can contribute to cell death, tissue loss, and ultimately to the development of functional impairments. However, there are currently no effective therapeutic interventions that improve brain outcomes following TBI. As a result, a number of experimental TBI models have been developed to recapitulate TBI injury mechanisms and to test the efficacy of potential therapeutics. The pig model has recently come to the forefront as the pig brain is closer in size, structure, and composition to the human brain compared to traditional rodent models, making it an ideal large animal model to study TBI pathophysiology and functional outcomes. This review will focus on the shared characteristics between humans and pigs that make them ideal for modeling TBI and will review the three most common pig TBI models–the diffuse axonal injury, the controlled cortical impact, and the fluid percussion models. It will also review current advances in functional outcome assessment measures and other non-invasive, translational TBI detection and measurement tools like biomarker analysis and magnetic resonance imaging. The use of pigs as TBI models and the continued development and improvement of translational assessment modalities have made significant contributions to unraveling the complex cascade of TBI sequela and provide an important means to study potential clinically relevant therapeutic interventions.

Selective CDK inhibitors:promising candidates for future clinical traumatic brain injury trials

Traumatic brain injury induces secondary injury that contributes to neuroinflammation, neuronal loss, and neurological dysfunction. One important injury mechanism is cell cycle activation which causes neuronal apoptosis and glial activation. The neuroprotective effects of both non-selective （Flavopiridol） and selective （Roscovitine and CR-8） cyclin-dependent kinase inhibitors have been shown across mukiple experimental traumatic brain injury models and species. Cyclin-depen- dent kinaseinhibitors, administered as a single systemic dose up to 24 hours after traumatic brain injury, provide strong neuroprotection-reducing neuronal cell death, neuroinflammation and neurological dysfunction. Given their effectiveness and long therapeutic window, cyclin-dependent kinase inhibitors appear to be promising candidates for clinical traumatic brain injury trials.

Cold water swimming pretreatment reduces cognitive deficits in a rat model of traumatic brain injury

A moderate stress such as cold water swimming can raise the tolerance of the body to potentially injurious events. However, little is known about the mechanism of beneficial effects induced by moderate stress. In this study, we used a classic rat model of traumatic brain injury to test the hypothesis that cold water swimming preconditioning improved the recovery of cognitive functions and explored the mechanisms. Results showed that after traumatic brain injury, pre-conditioned rats（cold water swimming for 3 minutes at 4℃） spent a significantly higher percent of times in the goal quadrant of cold water swim, and escape latencies were shorter than for non-pretreated rats. The number of circulating endothelial progenitor cells was significantly higher in pre-conditioned rats than those without pretreatment at 0, 3, 6 and 24 hours after traumatic brain injury. Immunohistochemical staining and Von Willebrand factor staining demonstrated that the number of CD34~＋ stem cells and new blood vessels in the injured hippocampus tissue increased significantly in pre-conditioned rats. These data suggest that pretreatment with cold water swimming could promote the proliferation of endothelial progenitor cells and angiogenesis in the peripheral blood and hippocampus. It also ameliorated cognitive deficits caused by experimental traumatic brain injury.

Effects of diazepam on glutamatergic synaptic transmission in the hippocampal CA1 area of rats with traumatic brain injury

The activity of the Schaffer collaterals of hippocampal CA3 neurons and hippocampal CA1 neurons has been shown to increase after lfuid percussion injury. Diazepam can inhibit the hy-perexcitability of rat hippocampal neurons after injury, but the mechanism by which it affects excitatory synaptic transmission remains poorly understood. Our results showed that diazepam treatment signiifcantly increased the slope of input-output curves in rat neurons after lfuid per-cussion injury. Diazepam signiifcantly decreased the numbers of spikes evoked by super stimuli in the presence of 15 μmol/L bicuculline, indicating the existence of inhibitory pathways in the injured rat hippocampus. Diazepam effectively increased the paired-pulse facilitation ratio in the hippocampal CA1 region following fluid percussion injury, reduced miniature excitatory postsynaptic potentials, decreased action-potential-dependent glutamine release, and reversed spontaneous glutamine release. These data suggest that diazepam could decrease the lfuid per-cussion injury-induced enhancement of excitatory synaptic transmission in the rat hippocampal CA1 area.

Effects of intrapulmonary percussive ventilation on airway mucus clearance: A bench model

AIM To determine the ability of intrapulmonary percussive ventilation(IPV) to promote airway clearance in spontaneously breathing patients and those on mechanical ventilation.METHODS An artificial lung was used to simulate a spontaneously breathing patient(Group 1), and was then connected to a mechanical ventilator to simulate a patient on mechanical ventilation(Group 2). An 8.5 mm endotracheal tube(ETT) connected to the test lung, simulated the patient airway. Artificial mucus was instilled into the mid-portion of the ETT. A filter was attached at both ends of the ETT to collect the mucus displaced proximally(mouth-piece filter) and distally(lung filter). The IPV machine was attached to the proximal end of the ETT and was applied for 10-min each to Group 1 and 2. After each experiment, the weight of the various circuit components were determined and compared to their dry weights to calculate the weight of the displaced mucus.RESULTS In Group 1(spontaneously breathing model), 26.8% ± 3.1% of the simulated mucus was displaced proximally, compared to 0% in Group 2(the mechanically ventilated model) with a P-value of < 0.01. In fact, 17% ± 1.5% of the mucus in Group 2 remained in the mid-portion of the ETT where it was initially instilled and 80% ± 4.2% was displaced distally back towards the lung(P < 0.01). There was an overall statistically significant amount of mucusmovement proximally towards the mouth-piece in the spontaneously breathing(SB) patient. There was also an overall statistically significant amount of mucus movement distally back towards the lung in the mechanically ventilated(MV) model. In the mechanically ventilated model, no mucus was observed to move towards the proximal/mouth piece section of the ETT. CONCLUSION This bench model suggests that IPV is associated with displacement of mucus towards the proximal mouthpiece in the SB patient, and distally in the MV model.

A Hydraulic Hammer Corer Utilizing Hydrostatic Energy for Hard Seafloor Sediment Coring

The paper presents the design and preliminary test results of a corer used for hard seafloor sediments sampling. Generally the sediment cores are provided by either gravity-type coting or deep-ocean drilling for a range of studies. However, in consideration of the operability and available sample length in collecting hard sediments, these methods exhibit no advantages. In this paper, a new corer which can exploit both hydrostatic energy and gravity energy for hard sediments coting is presented. The hydrostatic energy is provided by pressure differential between ambient seawater pressure and air pressure in an empty cavity. During sampling process, the corer penetrates into the sediment like a gravity corer and then automatically shifts to the percussion mode. The experiments in the laboratory indicate that the corer can complete 40 cycles in the sea with a cycle time of 2.8 seconds in percussion mode and impact the sample tube with the velocity of 0.2 m/s during each cycle. Besides, its adjustable falling velocity can make the corer achieve the maximum efficiency in coring different sediments.

An Analysis of the Origin of the Interaction Force between Electric Charges, including Justification of the ln<i>r</i>Term in the Completed Coulomb’s Law, in HM16 Ether

In this study, we demonstrate the correctness of our 2010 hypothesis regarding the need to complete Coulomb’s FC law with the term lnr, resulting in the completed FCC force. For this purpose, we consider the electrical interactions between charged microparticles (MPs), which develop as fundamental vibrations (FVs) in ether, producing the vibrational strains &epsilon;and &gamma;and the resulting stresses &sigma;and &tau;, as percussions of ether cells (ECs) upon the MP surface. The stresses &sigma;?and?&tau;produce a resultant force FP, due to the percussions which constitute the real electric force FCC. The spatial effect of ether on FP is demonstrated by an analytical method, considering the electrical interaction between MPs through various equidistant spatial paths li of FVs, modelled on the basis of the Huygens principle for waves. For this issue, we utilized a numerical calculation, which could be generalized. But this spatial effect of the ether leads at a very slow decreasing of the FP forces ratio rF when doubling the distance l, in contrast to Coulomb’s FC forces whose ratio rF?decreases accentuate with doubling l. Accordingly, the necessity of including the term ln r in the FCC force, which is limited to 1.0 for doubling l, at long distances, was justified.

Bifurcations and the penetrating rate analysis of a model for percussive drilling

In this paper, we investigate a low dimensional model of percussive drilling with vibro-impact to mimic the nonlinear dynamics of the bounded progression. Non- holonomity which arises in the stick-slip caused by the impact during drilling fails to be correctly identified via the classical techniques. A reduced model without non-holono- mity is derived by the introduction of a new state variable, of which averaging technique is employed successfully to detect the periodic motions. Local bifurcations are presented directly by using C-L method. Numerical simulations and the penetrating rate analysis along different choices of parame- ters have been carried out to probe the nonlinear behaviour and the optimal penetrating rate of the drilling system.