Burst Energy Research Articles

Guidewire electrosurgery-assisted trans-septal puncture.

Electrifying a coronary guidewire may be a simple escalation strategy when trans-septal needle puncture is unsuccessful. Radiofrequency energy to facilitate trans-septal puncture through a dedicated device is costly and directly through a trans-septal needle may be less safe. Our technique overcomes these limitations. The technique was used in patients when trans-septal needle penetration failed despite excessive force or tenting of the atrial septum. A coronary guidewire, connected to an electrosurgery pencil, was advanced through the trans-septal needle, dilator, and sheath to perforate the interatrial septum during a short burst of radiofrequency energy. With the guidewire tip no longer "active," the dilator and sheath were advanced safely over the wire into the left atrium. In posthoc validation, radiofrequency assisted Brockenbrough needle and coronary guidewire punctures were made in freshly explanted pig hearts and compared under microscopy. Eight patients who required trans-septal access for structural intervention were escalated to a guidewire electrosurgery strategy. Six patients had thickened fibrotic septum and two had prior surgical patch repair. Crossing was successful in all patients with no procedure related complications. The size of punctures (1.11 ± 0.40mm vs 0.37 ± 0.08mm, P = .009) and blanched penumbra (3.62 ± 1.23mm vs 0.72 ± 0.29mm, P = .003) in pig atrial septum were larger with an electrified needle than electrified guidewire. The hole generated by the electrified guidewire was smaller than by the nonelectrified needle. When conventional trans-septal puncture fails, a coronary guidewire can be used to deliver brief radiofrequency energy safely and effectively. This technique is inexpensive and accessible to operators.

A new energy index for evaluating the tendency of rockburst and its engineering application

Based on energy-transfer analysis of triaxial unloading tests under four different controlling conditions, the rock burst energy release rate (RBERR)-an energy index combining the local energy release rate (LERR) and the limit energy storage rate (LESR), was proposed. LERR refers to the values of the elastic strain energy release of an element after brittle failure, which indicates that RBERR>0 can be used to determine whether the element belongs to an excavation damage zone. RBERR was implemented to simulate the evolution process of rock damage and failure with advancing excavation face. The results predicted using RBERR were consistent with those obtained from an actual rockburst. In addition, a synthesis method based on microseismic (MS) monitoring information and RBERR simulation analysis was implemented for the Huainan coal mine. A study on the spatial- temporal evolutional laws of MS events built relationships between MS monitoring information and excavation process and; consequently, the potential danger areas of rockburst were determined. RBERR was used to analyze the location and intensity of rockburst in potential danger areas, which could be valuable in the design of rockburst- resistant measures in deep- buried construction.

Simultaneous X-Ray, Gamma-Ray, and Radio Observations of the Repeating Fast Radio Burst FRB 121102

Abstract We undertook coordinated campaigns with the Green Bank, Effelsberg, and Arecibo radio telescopes during Chandra X-ray Observatory and XMM-Newton observations of the repeating fast radio burst FRB 121102 to search for simultaneous radio and X-ray bursts. We find 12 radio bursts from FRB 121102 during 70 ks total of X-ray observations. We detect no X-ray photons at the times of radio bursts from FRB 121102 and further detect no X-ray bursts above the measured background at any time. We place a 5σ upper limit of 3 × 10−11 erg cm−2 on the 0.5–10 keV fluence for X-ray bursts at the time of radio bursts for durations ms, which corresponds to a burst energy of 4 × 1045 erg at the measured distance of FRB 121102. We also place limits on the 0.5–10 keV fluence of 5 × 10−10 and 1 × 10−9 erg cm−2 for bursts emitted at any time during the XMM-Newton and Chandra observations, respectively, assuming a typical X-ray burst duration of 5 ms. We analyze data from the Fermi Gamma-ray Space Telescope Gamma-ray Burst Monitor and place a 5σ upper limit on the 10–100 keV fluence of 4 × 10−9 erg cm−2 (5 × 1047 erg at the distance of FRB 121102) for gamma-ray bursts at the time of radio bursts. We also present a deep search for a persistent X-ray source using all of the X-ray observations taken to date and place a 5σ upper limit on the 0.5–10 keV flux of 4 × 10−15 erg s−1 cm−2 (3 × 1041 erg s−1 at the distance of FRB 121102). We discuss these non-detections in the context of the host environment of FRB 121102 and of possible sources of fast radio bursts in general.

Effects of Pulsed Versus Conventional Versus Combined Radiofrequency for the Treatment of Trigeminal Neuralgia: A Prospective Study

Background: During radiofrequency bursts of energy are applied to nervous tissue. The clinical advantages of this treatment remain unclear. Objectives: We compared the effectiveness and pain relief for idiopathic trigeminal neuralgia (TN) after continuous radiofrequency (CRF), pulsed radiofrequency (PRF), and combined continuous and pulsed radiofrequency (CCPRF) treatment of the Gasserian ganglion (GG). Study Design: We conducted a randomized prospective study. Forty-three patients were included. Eleven patients were treated with PRF at 42°C for 10 minutes (PRF group), 12 patients received CRF for 270 seconds at 75 °C (CRF group), and 20 patients received PRF for 10 minutes at 42°C followed by CRF for at 60°C for 270 seconds (CCPRF group). Setting: Assuit University Hospital, Pain and Neurology outpatient clinics. Methods: Patients were assessed for pain, satisfaction, and consumption of analgesics at baseline and 7 days, one month, 6 months, 12 months, and 24 months after the procedure. The incidence of complications, anesthesia dolorosa, weakness of muscles of mastication, numbness, and technical complications, was evaluated after the procedure. Results: Excellent pain relief was achieved after 6, 12, and 24 months, respectively in 95%, 85%, and 70% of patients with CCPRF; 75%, 75%, and reduced to 50% among patients with CRF; and 82%, reduced to 9.1%, and 0% of patients with PRF. No complications were recorded in 75% of patients in the CCPRF and PRF groups. There was one case of anesthesia dolorosa, 4 cases of masseter muscle weakness, and 5 cases of severe numbness recorded in the CRF group. Limitation: There was a small number of patients in each group. Conclusion: The best results were observed in the CCPRF group, followed by the CRF group, and then the PRF group.

Numerical Simulation of Combined Water Injection in Deep Coal Seam and Its Field Application for Dust Suppression and De-stressing: A Case Study at Dongtan Coal Mine, China

In order to achieve the best effects of water injection in coal seam, ANSYS software, which combines stress–strain relationship with computational fluid dynamics, was used to simulate the pressure and velocity field of coal seam under water injection pressures of 20 and 3 MPa for determining the optimal injection parameters. Simulation results showed that the high pressure could significantly enhance the wetting effect of coal, and that the water dilutive wet coal range under 20 MPa was about 1.93 times larger than that under 3 MPa. On this basis, the high and low pressure combined coal seam water injection technique was designed and applied to the #1305 fully mechanized top coal caving face in the Dongtan coal mine, and dust concentration and rock burst energy in the working face before and after water injection were statistically tested. It was found that the average reduction rates of total dust and respirable dust were 52.96 and 53.84% respectively, and that the released energy of a single rock burst was controlled within 105 J after adopting the combined technique. It is believed that the combined water injection technique has an obvious effect on dust control and rock burst prevention.

Influence of envelope waveform on ITD sensitivity of neurons in the auditory midbrain.

Interaural time differences (ITDs) conveyed by the modulated envelopes of high-frequency sounds can serve as a cue for localizing a sound source. Klein-Hennig et al. (J Acoust Soc Am 129: 3856, 2011) demonstrated the envelope attack (the rate at which stimulus energy in the envelope increases) and the duration of the pause (the interval between successive envelope pulses) as important factors affecting sensitivity to envelope ITDs in human listeners. Modulated sounds with rapid attacks and long pauses produce the lowest ITD discrimination thresholds. The duration of the envelope's sustained component (sustain) and the rate at which stimulus energy falls at the offset of the envelope (decay) are only minor factors. We assessed the responses of 71 single neurons, recorded from the midbrains of 15 urethane-anesthetized tri-colored guinea pigs, to envelope shapes in which the four envelope components, i.e., attack, sustain, decay, and pause, were systematically varied. We confirmed the importance of the attack and pause components in generating ITD-sensitive responses. Analysis of neural firing rates demonstrated more neurons (49/71) show ITD sensitivity in response to "damped" stimuli (fast attack and slow decay) compared with "ramped" stimuli (slow attack and fast decay) (14/71). Furthermore, the lowest threshold for the damped stimulus (91 μs) was lower by a factor of 4 than that for the temporally reversed ramped envelope shape (407 μs). The data confirm the importance of fast attacks and optimal pause durations in generating sensitivity to ITDs conveyed in the modulated envelopes of high-frequency sounds and are incompatible with models of ITD processing based on the integration of sound energy over time.NEW & NOTEWORTHY Using single-neuron electrophysiology, we show that the precise shape of a sound's "energy envelope" is a critical factor in determining how well midbrain neurons are able to convey information about auditory spatial cues. Consistent with human behavioral performance, sounds with rapidly rising energy and relatively long intervals between energy bursts are best at conveying spatial information. The data suggest specific sound energy patterns that might best be applied to hearing devices to aid spatial listening.

Effect of yield curves and porous crush on hydrocode simulations of asteroid airburst

AbstractSimulations of asteroid airburst are being conducted to obtain best estimates of damage areas and assess sensitivity to variables for asteroid characterization and mitigation efforts. The simulations presented here employed the ALE3D hydrocode to examine the breakup and energy deposition of asteroids entering the Earth's atmosphere, using the Chelyabinsk meteor as a test case. This paper examines the effect of increasingly complex material models on the energy deposition profile. Modeling the meteor as a rock having a single strength can reproduce airburst altitude and energy deposition reasonably well but is not representative of real rock masses (large bodies of material). Accounting for a yield curve that includes different tensile, shear, and compressive strengths shows that shear strength determines the burst altitude. Including yield curves and compaction of porous spaces in the material changes the detailed mechanics of the breakup but only has a limited effect on the burst altitude and energy deposition. Strong asteroids fail and create peak energy deposition close to the altitude at which ram dynamic pressure equals the material strength. Weak asteroids, even though they structurally fail at high altitude, require the increased pressure at lower altitude to disrupt and disperse the rubble. As a result, a wide range of weaker asteroid strengths produce peak energy deposition at a similar altitude.

The Advancing Role of Neuromodulation for the Management of Chronic Treatment-Refractory Pain.

Neuropathic pain is a common cause of disability and health care utilization. While judicious pharmacotherapy and management of comorbid psychological distress can provide for improved quality of life, some patients with treatment-refractory disease require more invasive therapies. Spinal cord stimulation can provide for improvement in pain and decrease in medication utilization, with level 1 evidence supporting its use across various pain etiologies including persistent postoperative neuropathic pain, complex regional pain syndrome, chronic inoperable limb ischemia, treatment refractory angina, and painful diabetic neuropathy. These procedures can be done with acceptably low morbidity and provide a cost-effective solution for those patients in whom medical therapies have failed. Technological innovation in lead design, implantable pulse generator capability, and stimulation algorithms and parameters may further enhance the success of this therapy. Neuromodulation of distal targets such as dorsal root ganglion may permit greater anatomic specificity of the therapy, whereas subthreshold stimulation with high-frequency or burst energy delivery may eliminate noxious and off-target paresthesiae. Such new technologies should be subject to rigorous evaluation as their mechanisms of action and long-term outcomes remain hitherto undefined.

A phase coherence approach to identifying co-located earthquakes and tremor

We present and use a phase coherence approach to identify seismic signals that have similar path effects but different source time functions: co-located earthquakes and tremor. The method used is a phase coherence-based implementation of empirical matched field processing, modified to suit tremor analysis. It works by comparing the frequency-domain phases of waveforms generated by two sources recorded at multiple stations. We first cross-correlate the records of the two sources at a single station. If the sources are co-located, this cross-correlation eliminates the phases of the Green’s function. It leaves the relative phases of the source time functions, which should be the same across all stations so long as the spatial extent of the sources are small compared with the seismic wavelength. We therefore search for cross-correlation phases that are consistent across stations as an indication of co-located sources. We also introduce a method to obtain relative locations between the two sources, based on back-projection of interstation phase coherence. We apply this technique to analyse two tremor-like signals that are thought to be composed of a number of earthquakes. First, we analyse a 20 s long seismic precursor to a M 3.9 earthquake in central Alaska. The analysis locates the precursor to within 2 km of the mainshock, and it identifies several bursts of energy—potentially foreshocks or groups of foreshocks—within the precursor. Second, we examine several minutes of volcanic tremor prior to an eruption at Redoubt Volcano. We confirm that the tremor source is located close to repeating earthquakes identified earlier in the tremor sequence. The amplitude of the tremor diminishes about 30 s before the eruption, but the phase coherence results suggest that the tremor may persist at some level through this final interval.

The sound of avalanches: from a global to a local perspective.

We present an experimental study aiming to understand the local origin of the acoustic bursts recorded globally during a two-dimensional shear experiment of a granular medium. In order to explain the power-law distribution of energy of these events (also called avalanches), the analysis focuses on their acoustic frequencies. Experiments with single grains have also been performed, trying to separate the contributions related to collision between neighbours from shear movements between grains. Preliminary results indicate that both frictional sliding and collision-like mechanisms are involved in the origin of the acoustic bursts. The evolution of the structure of the medium around a large acoustic burst is analysed both with high resolution and high-speed imaging. The energy of the acoustic bursts seems related to single and well-localised events with very large variations in energy. However, these local reorganisation processes may eventually bring the global relaxation of the system, which is also captured by a force drop in the resistance to shear.

Introduction: New Directions in Kentucky Sport History

Introduction:New Directions in Kentucky Sport History Andrew Doyle (bio) While few can doubt the outsized importance of sports in American culture, sport history was virtually ignored as a field of academic study for most of the twentieth century. Sport seemed one of the more trivial aspects of society: it was the "toy department of life," according to sportswriter Jimmy Cannon. The growing emphasis on social history in the 1970s and 1980s led to a burst of creative energy in the field of sport history, but there remained an implicit and sometimes explicit defensiveness in much of the early literature in the field. Yet, as the field has grown in size and scope, sport historians have demonstrated that it provides a useful, and in some ways unparalleled, means of exploring political, social, and economic configurations, cultural expression, and hierarchies of race and gender dominance. Any human activity that has commanded the attention of huge audiences across time and across cultures is, by definition, a worthy field of study. The power of sports to attract collective focus and stir human passions has grown dramatically over the course of the modern era, as has its power to change the relations of individuals to their societies and to one another. The symbiotic relationship between mass media and spectator sports was established in the late nineteenth century, and this has only grown in scope with the qualitative and quantitative expansion of the media landscape from print to electronic to digital. For the present, anyway, there is no end in sight. Jackie Robinson's desegregation of baseball was clearly a landmark [End Page 461] event in U.S. history, the annual spectacle of the Super Bowl speaks to who we are as a society and culture, and the Olympic Games and World Cup are events of global political, cultural, and economic significance. Spectator sports with mass audiences are clearly worthy subjects for the historian's focus, but sporting practices rooted in communities the world over provide other rich avenues of historical analysis. The competitive and non-competitive sporting pastimes of diverse human communities reflect value systems that often thrive in the interstices of a hegemonic culture. Sport thus offers a means of examining the sources and expressions of cultural power. It is a form of mass entertainment that both reflects and helps to shape the values of any society, past or present. Like such scripted forms as television, movies, and popular music, sport is an expression of social power and cultural values, but unlike them, sporting competition is unscripted. The passion and excitement of the arena is not a product of a filmmaker's artistry; the physical struggle of competition is real, as are the injuries. Both elite athletes and their fans experience the joys of winning and the pain of losing. They both share in the fleeting moments when a world record performance transcends previous human limits. A dramatic seventh game in a championship series and a Tuesday night game between two mid-major college basketball teams are each genuine in a way that is unmatched in any other form of mass entertainment. While sport holds no attraction for many, untold millions find no other form of entertainment that touches their spirit as deeply. Others find in sport an expression of group identity, especially marginalized groups who have used sport to challenge existing hierarchies of power. However, the fundamental reality of competition is true for those who compete at a much lower level or for those who compete only against their personal limitations. This was true for women in the early twentieth century who dared to play baseball or ice hockey, African American community groups who sponsored baseball leagues in the Jim Crow South, an ordinary worker who through-hikes the Appalachian Trail, or a weekend fitness enthusiast who builds her [End Page 462] strength and endurance in order to face the challenge of a triathlon. They all find something in sport that they can find in no other human endeavor, and historians have produced valuable scholarship on these and myriad other athletic activities. In this age of transnational and global history, there are still valuable perspectives to be gained by focusing on a...

Soliton interaction and further merging in normal-dispersion fiber lasers modeled with the cubic-quintic CGLE

We study the interaction and merging of optical solitons in normal-dispersion fiber lasers within the framework of the cubic-quintic complex Ginzburg–Landau equation (CGLE). We start finding homogeneous analytic solutions to this equation that are used in numerical simulations to build interacting kinks that lead to the formation of stable solitons. We then study numerically the interaction and merging of these solitons and characterize this process using moments such as the energy and momentum along the fiber. We have found that the merging process occurs only for small enough values of the initial distance (that depends on the phase difference) between solitons, otherwise they repel each other monotonically. The structure of the merging process shows a double peaked energy burst and (depending on the phase difference) a gain and/or loss of momentum. Finally, we propose a fitting model for isolated solitons in order to find a suitable analytical representation for the attractive interaction law before their merging.

Gravitational wave memory: A new approach to study modified gravity

It is well known that two types of gravitational wave memory exist in general relativity (GR): the linear memory and the nonlinear, or Christodoulou, memory. These effects, especially the latter, depend on the specific form of the Einstein equation. It can then be speculated that, in modified theories of gravity, the memory can differ from the GR prediction and provides novel phenomena to study these theories. We support this speculation by considering scalar-tensor theories, for which we find two new types of memory: the T memory and the S memory, which contribute to the tensor and scalar components of a gravitational wave, respectively. Specifically, the former is caused by the burst of energy carried away by scalar radiation, while the latter is intimately related to the no scalar hair property of black holes in scalar-tensor gravity. We estimate the size of these two types of memory in gravitational collapses and formulate a detection strategy for the S memory, which can be singled out from tensor gravitational waves. We show that (i) the S memory exists even in spherical symmetry and is observable under current model constraints, and (ii) while the T memory is usually much weaker than the S memory, it can become comparable in the case of spontaneous scalarization.

Laboratory study of low-β forces in arched, line-tied magnetic flux ropes

The loss-of-equilibrium is a solar eruption mechanism whereby a sudden breakdown of the magnetohydrodynamic force balance in the Sun's corona ejects a massive burst of particles and energy into the heliosphere. Predicting a loss-of-equilibrium, which has more recently been formulated as the torus instability, relies on a detailed understanding of the various forces that hold the pre-eruption magnetic flux rope in equilibrium. Traditionally, idealized analytical force expressions are used to derive simplified eruption criteria that can be compared to solar observations and modeling. What is missing, however, is a validation that these idealized analytical force expressions can be applied to the line-tied, low-aspect-ratio conditions of the corona. In this paper, we address this shortcoming by using a laboratory experiment to study the forces that act on long-lived, arched, line-tied magnetic flux ropes. Three key force terms are evaluated over a wide range of experimental conditions: (1) the upward hoop force; (2) the downward strapping force; and (3) the downward toroidal field tension force. First, the laboratory force measurements show that, on average, the three aforementioned force terms cancel to produce a balanced line-tied equilibrium. This finding validates the laboratory force measurement techniques developed here, which were recently used to identify a dynamic toroidal field tension force that can prevent flux rope eruptions [Myers et al., Nature 528, 526 (2015)]. The verification of magnetic force balance also confirms the low-β assumption that the plasma thermal pressure is negligible in these experiments. Next, the measured force terms are directly compared to corresponding analytical expressions. While the measured and analytical forces are found to be well correlated, the low-aspect-ratio, line-tied conditions in the experiment are found to both reduce the measured hoop force and increase the measured tension force with respect to analytical expectations. These two co-directed effects combine to generate laboratory flux rope equilibria at lower altitudes than are predicted analytically. Such considerations are expected to modify the loss-of-equilibrium eruption criteria for analogous flux ropes in the solar corona.

Direct SAR mapping by thermoacoustic imaging: A feasibility study.

To develop a new method capable of directly measuring specific absorption rate (SAR) deposited in tissue using the thermoacoustic signal induced by short radiofrequency (RF) pulse excitation. A detailed model based on the thermoacoustic wave generation and propagation is presented. We propose a new concept for direct measurement of SAR, to be used as a safety assessment/monitoring tool for MRI. The concept involves the use of short bursts of RF energy and the measurement of the resulting thermoacoustic excitation pattern by an array of ultrasound transducers, followed by image reconstruction to yield the 3D SAR distribution. We developed a simulation framework to model this thermoacoustic SAR mapping concept and verified the concept in vitro. Simulations show good agreement between reconstructed and original SAR distributions with an error of 4.2, 7.2, and 8.4% of the mean SAR values in axial, sagittal, and coronal planes and support the feasibility of direct experimental mapping of SAR distributions in vivo. The in vitro experiments show good agreement with theory (r2 = 0.52). A novel thermoacoustic method for in vivo mapping of local SAR patterns in MRI has been proposed and verified in simulation and in a phantom experiment. Magn Reson Med 78:1599-1606, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

“Coming to Terms with the Past Will Allow One to Continue”: Interview with Leyla Bouzid about As I Open My Eyes

“Coming to Terms with the Past Will Allow One to Continue”: Interview with Leyla Bouzid about As I Open My Eyes Olivier Barlet Translated by Beti Ellerson In French theaters on December 23, 2015, As I Open My Eyes is an event: the revelation of a young Tunisian filmmaker and a film of great significance. This interview, which focuses particularly on the cinematic gesture, is a useful way of measuring its importance. Olivier Barlet: Why the title As I Open My Eyes? Leyla Bouzid: It reflects the eighteen-year-old character Farah as she opens her eyes to life, but also it is about her raised consciousness throughout the film. It also relates to the emerging awareness of her mother. Similarly, it is about a country opening its eyes to its reality. And in a more down-to-earth way, it is the title of a recurring song in the film. OB: With Farah, is it not the opportunity for you to show what you have lived, your youth? LB: It has often been said and believed that the Tunisia under Ben Ali was cool; however, I grew up in an environment where this was not the case. When the revolution took place, I had a strong urge to return to this period. OB: The film is constructed on the contrasting elements of the vitality of Farah and her band on the one hand and the concessions of the other adults on the other. But one wonders whether the adult element will gradually take over in terms of safeguarding this vital energy that will become the revolution. [End Page 207] LB: This very forceful momentous energy is at the heart of the film and was the basis of the artistic choices at all levels. For me, this burst of energy will gradually contaminate the generation of adults, the city, etc., though constantly confronted with attempts to stifle it. Everyone will try to tame this energy. Will this energy be ultimately crushed? This is the suspense of the film. OB: You mention the artistic choices. They are indeed striking, in the way of filming the concerts with Farah’s constant fluctuations. LB: Yes, the film has this energy that takes it to a final calm. In writing the script, I cut the scenes as short as possible, which gives this sense of energy. For the group, there could have been a fake band with perfect playback, but I wanted to capture that live energy, perhaps with off-key notes and a bit on the rough side. We dialogued a great deal with the cinematographer and musician regarding the rehearsal and concert scenes. OB: You’re not a musician, though the music and songs have an important place in the film. What was your experience in this context? LB: It was the big challenge of the film! The music is very relevant: a song can spread very quickly without the authorities able to control it. I wrote suggestive texts, with emotional color for each song, and during the preparation stage, I went to see a friend, Ghassen Amami, who writes beautiful lyrics in Tunisian. Some were written in one setting and others after going back and forth. For the musicians, I wanted an electric rock band with electric oud, but that would be an acoustic mix of rock and electronic music with the energy of popular traditional Tunisian music, of mezoued, of mensiettes, etc. 1 I met a lot of musicians but only through a chance encounter I was able to find Khyam Allami, who is Syrian and has lived a bit in Tunisia. He is an oud virtuoso but also has the rock band Alif Ensemble. We shared the same interest in grouping influences within the same momentum. He put himself into the skin of a young Tunisian of 2010 and it was very productive. He wrote the music, especially for the voice of Baya Medhaffar, who played the role of Farah. He also helped me during the casting, worked with the musicians at rehearsals, was present during the shooting of the music scenes, ensured that the performances took place live, was there during the sound mixing, etc. And, as he...

Analysis of fractal characteristic of fragments from rock burst tests under different loading rates

Original scientific paper Rock burst is a common serious geological hazard in underground engineering, which seriously affects the progress of projects. The mechanism of rock burst can be explained by the distribution law of rock fragments and its fractal characteristics. A simulation experiment of rock burst was conducted with the granite samples under a biaxial loading machine system to analyze the fractal characteristics of the fragments from rock burst tests. The granite fragments were collected and divided into coarse, medium, fine, and micro grains by a screening method. The number and mass distribution of the fragments in different size ranges were also analyzed. The fractal dimensions of the rock fragments were calculated by the mass-granularity distribution method. Results show that the loading rate is proportional to the damage degree of rock burst; the mass of rock burst debris increases with the increase in loading rate, which indicates that a high loading rate leads to considerable rock damage. A high loading rate also results in small proportions of fine and medium grains and a large proportion of coarse grain, with no significant change in the micro grain. Under the high-loading-rate condition, the fractal dimensions of rock fragments are small, but the released energy of rock burst is large. The conclusions obtained in this study confirm the feasibility of reducing the risk of rock burst by adjusting the excavation rate in engineering practice and provide the basis for further study on the mechanism of rock burst.

Tectonic tremor and slow slip along the northwestern section of the Mexico subduction zone

The southwestern coast of Mexico is marked by active subduction of the Rivera and Cocos plates, producing megathrust earthquakes that tend to recur every 50–100 yr. Herein, we use seismic and GPS data from this region to investigate the potential relationship between earthquakes, tectonic (non-volcanic) tremor, and transient slip along the westernmost 200 km of the Mexico subduction zone. Visual examination of seismograms and spectrograms throughout the 18-month-long MARS seismic experiment reveals clear evidence for frequent small episodes of tremor along the Rivera and Cocos subduction zones beneath the states of Jalisco, Colima, and Michoacán. Using a semi-automated process that identifies prominent energy bursts in envelope waveforms of this new data, analyst-refined relative arrival times are inverted for source locations using a 1-D velocity model. The resulting northwest–southeast trending linear band of tremor is located downdip from the rupture zones of the 1995 Mw 8.0 Colima–Jalisco and 2003 Mw 7.2 Tecoman subduction-thrust earthquakes and just below the regions of afterslip triggered by these earthquakes. Despite the close proximity between tremor and megathrust events, there is no evidence that the time since the last great earthquake influences the spatial or temporal pattern of tremor. A well-defined gap in the tremor beneath the western Colima Graben appears to mark a separation along the subducted Rivera–Cocos plate boundary. From the position time series of 19 continuous GPS sites in western Mexico, we present the first evidence that slow slip events occur on the Rivera plate subduction interface. Unlike the widely-recorded, large-amplitude, slow slip events on the nearly horizontal Cocos plate subduction interface below southern Mexico, slow slip events below western Mexico have small amplitudes and are recorded at relatively few, mostly coastal stations. The smaller slow slip beneath western Mexico may be due to the steeper dip, causing a narrower zone where the conditions for slow slip are met. The prominent afterslip following the M=8 1995 Colima–Jalisco and M=7.2 2003 Tacoma megathrust earthquakes may also shrink the area available for episodic slow slip.

Electroporation-assisted inactivation of Escherichia coli using nisin-loaded pectin nanoparticles

Abstract Pulsed electric fields (PEF) trigger the electroporation phenomenon in cell membranes, which has found many biotechnological applications including food processing. Nisin is a prominent lantibiotic widely used as a food preservative due to its high potency against many bacteria; its efficacy depends on various environmental factors and nisin resistance is a common problem. In this work we have applied novel nisin-loaded pectin nanoparticles in combination with sub-microsecond and microsecond range electroporation for inactivation of nisin-resistant Escherichia coli. The 5–30 kVcm− 1 square wave 1 kHz pulse bursts of 250 ns, 500 ns, and 100 μs were used. The PEF treatment combined with nisin nanoparticles further improved the inactivation efficacy (up to 3.7 log reduction) compared to separate procedures (up to 1.5 log reduction); this effect is scalable and does not depend on the cell concentration. Industrial relevance We have designed experiments and provided data that has direct application in food preservation and processing. Nisin is a prominent lantibiotic that is widely used as a food preservative due to its high potency against many bacteria. Nevertheless, its efficacy depends on various environmental factors and the nisin resistance is a common problem. We have used the pectin encapsulation that allowed addressing the susceptibility of nisin to environmental factors such as pH or food composition, while the PEF technology enabled a non-thermal increase of the membrane permeabilization and overcoming the nisin-resistance of the bacteria. We have also shown that the only reason to use submicrosecond pulses instead of the microsecond ones for eradication of the bacteria is the possible minimization of energy costs for generation of PEF. If the total energy of the pulse burst is the same the inactivation efficacy is also identical.

Lithium-Ion Capacitor Based on Electrodes Constructed Via Electrostatic Spray Deposition

Conventional Electrochemical double-layer capacitors (EDLCs) are well suited as power devices that can provide large bursts of energy in short time periods. However, their relatively poor energy densities hinder their application in devices that require a simultaneous supply of both high energy and high power. In the wake of addressing this shortcoming of EDLCs, the concept of hybridization of lithium-ion batteries (LIBs) and EDLCs has gained significant scientific interest in past few years. Such a device, generally referred to as the “lithium-ion capacitor” typically utilizes a lithium intercalating electrode along with a fast charging capacitor electrode in a lithium-containing electrolyte. Herein we have constructed a lithium ion capacitor comprising a Li4Ti5O12 –TiO2 (LTO-TiO2) anode and a graphene and carbon nanotube (G-CNT) composite cathode using electrostatic spray deposition (ESD). The morphology and material properties were studied using scanning and transmission electron microscopy and X-ray diffraction studies, respectively. Electrochemical characterization was thereafter carried out for both the half cells as well as full cells.