Single Hole Research Articles

High-speed drill craniostomy as a minimally invasive method of chronic subdural hematoma management. Preliminary results of a pilot study

Objectives: The objective of this study was to assess the safety and efficiency of minimally invasive high-speed drill craniostomy in the treatment of chronic subduralhematomas.Study design: The study was designed as a retrospective case series study.Patients and Methods: The patients with compressive chronic subdural hematomas were treated by minimally invasive high-speed craniostomy performed underlocal anesthesia or conscious sedation. A minimal skin incision was followed by a single high-speed drill hole placement in the frontal or parietal region, over the area of maximal hematoma thickness. After hematoma aspiration, a 1.9 mm silicone catheter was placed in subdural space and connected to gravity-assisteddrainage. Patients were ambulatory immediately after surgery. Data on clinical course and outcome were recorded and analyzed.Results: There were 23 patients (5 female, 21.7%) included in the study. The median patient age was 77.5 years (interquartile range 67 - 83). Six (26.1%) of the patients had bilateral subdural hematomas. Septated/multiloculated hematomas were observed in 6 (26.1%) patients. Heterodense hematomas denoting more recent bleeding were recorded in 16 (69.5%) patients. The median duration of subdural drainage was 4 days (interquartile range 3 to 5). The median length of hospital stay was 9.5 days (interquartile range 6 - 16). One patient died of sepsis following a nosocomial respiratory infection. One patient developed a wound infection with subdural empyema, requiring subsequent craniotomy. One patient had deep venous thrombosis and pulmonary embolism. In all patients, postoperative CT scans showed a significant reduction of hematoma volume and midline shifting. No postoperative seizures were observed.Conclusion: High-speed drill craniostomy is a safe, simple, straightforward, and effective treatment for the management of chronic subdural hematomas, including multiloculated and heterodense lesions. Elderly patients could most benefit from such a procedure, avoiding general anesthesia, prolonged intracranial procedures, and lengthy hospital stays.

Numerical investigation of an improved deep-hole presplitting method based on notched blasting for deep-buried high sidewall structures

Under high stress conditions, the local stress concentration in the high sidewall structure of a deeply buried powerhouse is obvious, and sidewall presplitting formation is significantly affected. For deep hole presplitting blasting (DHPB) widely used in underground powerhouse, the non-uniform stress characteristics of DHPB were first revealed through three-dimension (3D) numerical simulation, and three crack formation modes were subsequently classified. Afterwards, an improved excavation method of notched blasting fusion to DHPB was proposed to reduce the difficulty and inhomogeneity of DHPB brought by complex stress environment. A single hole 3D model was used to confirm the stronger guiding effect of notched blasting on crack expansion when the maximum principal stress direction is different from its. And the feasibility of the improved presplitting method on high sidewalls is pointed out by 3D numerical simulation. The results show that, for DHPB, the stress concentration at sidewall foot induced by powerhouse excavation causes a gradual change in its stress environment, and the horizontal lateral pressure coefficient (Ratio of transverse to axial) decreases with hole depth basically, while there may be a principal stress direction dividing point with a coefficient of 1.0. The direction of crack formation near the top of presplitting holes tends to be lateral to the powerhouse, whereas that near the bottom of presplitting holes tends to be axial to the powerhouse. This effect is exacerbated further by continuous undercutting of the lower and middle parts, resulting in more uneven pre-cracking of DHPB. The improved excavation method based on notched blasting can ensure that the notched direction is the dominant crack expansion direction among both notch cutting and maximum principal stress direction, weaken the influence of uneven stress environment on the presplitting formation, and re-achieve the good crack formation between holes of DHPB.

Plume characterization of a waveguide ECR thruster

A circular waveguide electron cyclotron resonance plasma thruster prototype driven by microwaves at 5.8 GHz (80–300 W) is characterized. The magnetic field is generated by a combination of Sm-CoYXG32 magnets and an electromagnet, which enables the tuning of the resonance position and magnetic nozzle shape. The main plasma plume properties are analyzed by using electrostatic probes when the mass flow rate (Xenon), microwave power, electromagnet current, and propellant injector design are varied. An estimation of the propulsive performance of the device is also presented. Results show that a single radial injector hole is not sufficient for a symmetric ion current profile and that magnetic nozzle shape and strength tuning can significantly affect the divergence angle and thruster floating potential. A utilization efficiency of up to 70% and electron temperatures of up to 16 eV have been measured.

Improving CO2 photoconversion with ionic liquid and Co single atoms

Photocatalytic CO2 conversion promises an ideal route to store solar energy into chemical bonds. However, sluggish electron kinetics and unfavorable product selectivity remain unresolved challenges. Here, an ionic liquid, 1-ethyl-3-methylimidazolium tetrafluoroborate, and borate-anchored Co single atoms were separately loaded on ultrathin g-C3N4 nanosheets. The optimized nanocomposite photocatalyst produces CO and CH4 from CO2 and water under UV–vis light irradiation, exhibiting a 42-fold photoactivity enhancement compared with g-C3N4 and nearly 100% selectivity towards CO2 reduction. Experimental and theoretical results reveal that the ionic liquid extracts electrons and facilitates CO2 reduction, whereas Co single atoms trap holes and catalyze water oxidation. More importantly, the maximum electron transfer efficiency for CO2 photoreduction, as measured with in-situ μs-transient absorption spectroscopy, is found to be 35.3%, owing to the combined effect of the ionic liquid and Co single atoms. This work offers a feasible strategy for efficiently converting CO2 to valuable chemicals.

Space-Confined Carbon-Doped Pd Nanoparticles as a Highly Efficient Catalyst for Selective Phenol Hydrogenation

Pd-based catalysts have been widely applied in hydrogenation reactions for production of both bulk and fine chemicals; however, selective and efficient hydrogenation of substrates with multiple functional groups is challenging. Here, we synthesize the C-doped Pd NPs confined in the hollow-structured carbons with a closed shell (C-Pd@HCS), a single hole in the shell (C-Pd@HCH), and a bowl-like shell (C-Pd@HCB). Based on the three comparative samples, void-confinement effects in phenol hydrogenation are investigated. It is found that the reaction rate of phenol hydrogenation is always decelerated gradually in the order of C-Pd@HCS > C-Pd@HCH > C-Pd@HCB, regardless of what reaction conditions are applied. The highest rate over C-Pd@HCS should be related to the void-confinement effect induced by its closed space. Moreover, the selectivity toward cyclohexanone over C-Pd@HCS/HCH/HCB is always higher than 95% due to the C-doped Pd NPs (hindering the Pd β-hydride formation and disfavoring the cyclohexanone adsorption as revealed by experimental and theoretical results).

Gravitational Waves from the Merger of Two Primordial Black Hole Clusters

The orbital evolution of a binary system consisting of two primordial black hole clusters is investigated. Such clusters are predicted in some theoretical models with broken symmetry in the inflation Lagrangian. A cluster consists of the most massive central black hole surrounded by many smaller black holes. Similar to single primordial black holes, clusters can form gravitationally bounded pairs and merge during their orbital evolution. The replacement of single black holes by such clusters significantly changes the entire merger process and the final rate of gravitational wave bursts in some parameter ranges (with sufficiently large cluster radii). A new important factor is the tidal gravitational interaction of the clusters. It leads to an additional dissipation of the orbital energy, which is transferred into the internal energy of the clusters or carried away by black holes flying out of the clusters. Comparison with the data of gravitational-wave telescopes allows one to constrain the fractions of primordial black holes in clusters, depending on their mass and compactness. Even the primordial black hole fraction in the composition of dark matter ≃1 turns out to be compatible with LIGO/Virgo observational data, if the black holes are in clusters.

Testing the black hole area law with Event Horizon Telescope

Hawking's black hole area theorem can be tested by monitoring the evolution of a single black hole over time. Using current imaging observations of two supermassive black holes M87* and Sgr A* from the Event Horizon Telescope (EHT), we find their horizon area variation fractions are consistent with the prediction of the black hole area law at the confidence level. We point out that whether the black hole area law is valid or not could be determined by future high-precision EHT observations of Sgr A*.

Laser ultrasonic imaging of subsurface defects with the linear sampling method.

Laser ultrasonics is a remote nondestructive evaluation technique suitable for real-time monitoring of fabrication processes in semiconductor metrology, advanced manufacturing, and other applications where non-contact, high fidelity measurements are required. Here we investigate laser ultrasonic data processing approaches to reconstruct images of subsurface side drilled holes in aluminum alloy specimens. We demonstrate through simulation that the model-based linear sampling method (LSM) can perform accurate shape reconstruction of single and multiple holes and produce images with well-defined boundaries. We experimentally confirm that LSM produces images that represent the internal geometric features of an object, some of which may be missed by conventional imaging.

Grouting mechanism and experimental study of goaf considering filtration effect.

The filtration effect significantly affects the gangue slurry velocity and concentration, making it difficult to evaluate the gangue slurry diffusion range. Based on the Darcy seepage law, a seepage theoretical calculation model is established considering the filtration time and space effect. And the "water-cement ratio change matrix" in the seepage process of coal gangue slurry is deduced, revealing the basic mechanism of the porous media filtration effect, and the water-cement ratio gradually increases in the seepage process of gangue slurry. The visual test platform for slurry diffusion in goaf was independently developed for testing. The active heating optical fiber method (AHFO) was used to monitor the flow and diffusion of coal gangue slurry in the collapse zone of goaf, and the gravity gradient and water cement ratio of slurry in goaf were measured. The law of particle sedimentation in the gangue slurry flow process under the filtration effect was revealed, and engineering verification was carried out. The results show that the average slope of the gangue slurry in the gangue accumulation is 6.34%, and the overall flow law of the gangue slurry in the goaf is the first longitudinal expansion and then transverse diffusion. The water-cement ratio near the grouting mouth is smaller than the initial water-cement ratio, the near-end water-cement ratio is smaller, and the far-end water-cement ratio is larger. During on-site filling, the accumulated grouting volume of a single hole is 700 m3, and the gangue slurry diffusion distance is greater than 45m, indicating that the gangue slurry has good fluidity.

Pomiar zużycia energii w trakcie cyklu wiercenia termicznego

The work presents the issue of measuring and analyzing energy consumption during a thermal drilling cycle. A research stand based on a CNC lathe was presented, the equipment of which was an experimental energy consumption system based on an electricity meter and a force gauge. The measuring devices used allowed for recording the load on the power grid, the load on the machine tool drives, the axial force, the drill braking torque, the current rotation of the machine tool spindle, the position of the drill in relation to the workpiece and the values of auxiliary parameter registers in the strategy of adaptive feed control. Two cases of a drilling cycle were considered: making a single hole and making a series of holes in one cycle. Five feed control strategies were tested during the drilling cycle, including adaptive feed control and a recursive feed optimization method. For comparison, holes were also made with traditional HSS twist drills. Based on the obtained test results, it can be concluded that the friction drilling method can be included in the energy-saving methods of making holes in thin-walled elements.

Cocoons, Fungi, Nematodes, Rhizoids, Annelids, Eggs, Arthropoda in Gale Crater, Mars?

White and dark gray oblong-ovoid cocoon-egg-like forms (“cocoon-eggs”), less than a mm in diameter, many with a single hole in one end, and some with unidentifiable specimens protruding from (exiting or entering) these holes, were photographed on mudstone in Gale Crater, Mars, on Sol 1302. If biological some of these cocoon-eggs may be frozen, fossilized or have already “hatched” or undergone metamorphosis. Specimens resembling segmented and tubular worms and rhizoids and those with multiple appendages (Arthropoda) were also photographed on these and other substrates on Mars, including on Sols 130, 132, 302, 551, 553, 808, 809, 868, 906, 1280, 1921, in Gale Crater. Many Sol 1302 “cocoon-eggs” are embedded in substrate that appears to consist entirely of a coral-stromatolite-like mass of worm- and larvae-like forms; and similar worm and segmented larvae forms appear in the interior of three semi-transparent ovoid structures. Embedded in the soil surrounding these “cocoon-eggs” are numerous concave patches reminiscent of dried “egg-yolk,” cocoon remnants or fungus, and that may represent the final stage of “cocoon” collapse and disintegration; or they are fungal in origin. Some of the segmented and tubular worm-like forms may include rhizoids and tubular fungi. Ovoids with open apertures may be evidence of fungal sporing. The possibility that fungus and diverse species and their “cocoons” share the same substrate is supported by what appears to be cyanobacteria, worms, insecta (arthropoda), and stalks topped by ovoids or ovoid-shaped microbialite-like sediment. Fungi, lichens, cyanobacteria, stromatolites and arthropoda have been previously reported in other areas of Gale Crater, whereas fungal “puffballs” and specimens attached to rocks with stalks and topped with mushroom-like caps have been observed in Meridiani Planum. The possibility these specimens are abiogenic cannot be ruled out. The evidence, in our view, arguably supports the hypotheses that various organisms colonized Mars in the ancient or recent past.

A prospective randomized controlled trial of the effect of the number of burr hole on chronic subdural hematoma recurrence: An institutional experience

ObjectiveThe purpose of this study was to compare the effect of single burr hole (SBH) versus double burr hole (DBH) drainage on the recurrence rate of chronic subdural hematoma (CSDH). MethodForty-four patients undergoing burr hole craniostomy (BHC) between July 2022 and December 2022 were enrolled in a randomized clinical trial (RCT) comparing SBH to DBH surgeries. The primary endpoint of this study was the recurrence rate of CSDH. Radiological characteristics such as midline shift, thickness, volume, density, type of hematoma, brain atrophy and so on were secondary endpoints. ResultsForty-four patients participated in this study. Twenty-two hematomas underwent SBH craniostomy, and the other 22 had DBH craniostomy. The mean age in the SBH and DBH groups were 68.59 ± 7.94 and 69.54 ± 10.58, respectively. In each group, the proportion of males (SBH=16; DBH=15) was higher than that of females (SBH=6; DBH=7). The mean surgery time in the SBH group was significantly less than in the DBH group (p = 0.001). However, the two groups had no statistically significant difference in the CSDH recurrence rate (p = 0.312). ConclusionOur findings showed that SBH craniostomy is equally effective as DBH craniostomy at draining hematomas and does not increase the recurrence rate. Contrarily, the SBH craniostomy had a shorter surgical duration than the DBH craniostomy. As a result, we recommend SBH surgeries for all patients, with emphasis on the elderly and those with severe comorbidities, as well as in situations with few surgical facilities and a high patient admission rate.

Mode locking of hole spin coherences in CsPb(Cl, Br)3 perovskite nanocrystals

The spin physics of perovskite nanocrystals with confined electrons or holes is attracting increasing attention, both for fundamental studies and spintronic applications. Here, stable {{{{{{{rm{CsPb}}}}}}}}{({{{{{{{{rm{Cl}}}}}}}}}_{0.56}{{{{{{{{rm{Br}}}}}}}}}_{0.44})}_{3} lead halide perovskite nanocrystals embedded in a fluorophosphate glass matrix are studied by time-resolved optical spectroscopy to unravel the coherent spin dynamics of holes and their interaction with nuclear spins of the 207Pb isotope. We demonstrate the spin mode locking effect provided by the synchronization of the Larmor precession of single hole spins in each nanocrystal in the ensemble that are excited periodically by a laser in an external magnetic field. The mode locking is enhanced by nuclei-induced frequency focusing. An ensemble spin dephasing time {T}_{2}^{ * } of a nanosecond and a single hole spin coherence time of T2 = 13 ns are measured. The developed theoretical model accounting for the mode locking and nuclear focusing for randomly oriented nanocrystals with perovskite band structure describes the experimental data very well.

Flexible neuroendoscopy for endoscopic third ventriculostomy and fourth ventricular arachnoid cyst fenestration in an infant.

Arachnoid cysts of the fourth ventricle are rarely reported. Management options include CSF diversion, cyst fenestration, or cyst excision. Fenestration can be done via open microsurgical technique or endoscopically with or without simultaneous third ventriculostomy; and both rigid and flexible endoscopy have been used successfully. However, application of this treatment modality in pediatric patients is not well described. Therefore, to their knowledge, the authors report the first successful treatment of a fourth ventricular arachnoid cyst with a single frontal burr hole entry point for third ventriculostomy and fourth ventricular arachnoid cyst fenestration performed using flexible neuroendoscopy. The patient was a 13-month-old boy presenting with progressive macrocephaly. The authors review their technique, discuss special considerations when using this approach, and include an annotated intraoperative video for demonstration to help instruct and guide management. The authors demonstrate with an example that a single frontal burr hole entry point for flexible endoscopic third ventriculostomy and navigation through a dilated cerebral aqueduct for fourth ventricular arachnoid cyst fenestration is a viable treatment for symptomatic fourth ventricular arachnoid cysts in children.

Hydrodynamical Simulations of Black Hole Binary Formation in AGN Disks

We study close encounters between two single black holes (BHs) embedded in an AGN disk using a series of global 2D hydrodynamics simulations. We find that when the disk density is sufficiently high, bound BH binaries can be formed by the collision of their circum-single disks. Our analysis demonstrates that, after a BH pair passes the pericenter of their relative trajectory, post-collision gas drag may slow down the BHs, possibly forcing the two BHs to stay tightly bound. A binary formed by a close encounter can have a compact semimajor axis, large eccentricity, and retrograde orbital angular momentum. We provide a fitting formula that can accurately predict whether a close encounter can form a binary based on the gas mass and the incoming energy of the encounter. This fitting formula can be easily implemented in other long-term simulations that study the dynamical evolution of BHs in active galactic nucleus disks.

A Comparison Of Single And Multiple Jets In Terms Of Aeration Efficiency

Water treatment is required to meet the needs of an ever-increasing population. A variety of aeration strategies can be used to aerobically maintain liquid waste by supplying an adequate supply of oxygen to microorganisms present in the organic content of wastewater. In this investigation, seven different screens with single and multiple holes totaling 30.75 cm2 were used. The screens were designed to accommodate a variety of jet counts. The influence of variables such as the number of jets, discharge, and froude no on aeration efficiency was studied. The discharge rates of 4.750 l/s, 3.84 l/s, and 3.41 l/s were tested on each screen. The results suggest that the variables studied had a significant impact on aeration efficiency.

Ferrets (Mustela furo) Are Aware of Their Dimensions.

Self-awareness is a complex phenomenon expressed as the ability of an individual to separate "self-entity" from "other entity". One of its earliest evolutionary components is body size awareness, namely, the ability to consider the boundaries of one's own body as factors influencing interaction with surrounding objects. For ferrets, Mustela furo, the task requiring the penetration of various holes is ecologically relevant. We designed an experimental study in which the ferrets were supposed to select one opening out of three to get the bait. The first experiment was aimed at studying whether ferrets would prefer the holes basing on the hole size. In the second experiment, we tested the ferrets' ability to select a single passable hole on the first try while the impassable ones were larger in area. Results from the first experiment show that when choosing from the three passable openings, the animals preferred the shortest path to the bait and ignored the size of the holes. In the second experiment, all tested ferrets preferred to penetrate the passable opening on the first attempt, even though the areas of the two impenetrable ones were larger. We argue that these data indicate that ferrets are aware of their own body size.

Finite Element Analysis of Split Sleeve Cold Expansion Process on Multiple Hole Aluminum Alloy.

Multiple cold expansion holes are widely used in connection areas of aircraft structures, in order to achieve uniform load transfer of the skin or connection parts. Split sleeve cold expansion (SSCE) is widely used to enhance the fatigue life of fastener holes by applying compressive residual stresses around the holes. In this study, the finite element method (FEM) was used to research the distribution and variation of residual stresses along the hole edges of 7075AA single-hole and multi-hole cold expansion (CE) specimens. Full-field strain measurements of single-hole and multi-hole specimens were performed using two-dimensional digital image correlation (DIC), and the residual stress and strain at the hole edge of the specimens measured by FEM and DIC were compared. FEM results shows that the maximum circumferential and radial residual stresses of three-hole specimens with three-hole spacing are increased by 5.37% and 31.53% compared with single-hole specimens. The maximum circumferential residual stress of three-hole specimens with four-hole spacing increases by 7.25% compared with a single hole, but the radial residual stress decreases by 12.98%. In addition, for three-hole specimens with hole spacing three times the hole diameter, the strengthening effect of SSCE in the order of middle hole, then left hole, and, finally, right hole is better than that of SSCE in the order of left to right hole. FEM and DIC full-field strain results are basically consistent.

Tunable hole spin-photon interaction based on g -matrix modulation

The large spin-orbit interaction of holes in semiconductors is key to achieving strong spin-photon coupling in spin circuit-QED experiments. Here, the authors show that for a single hole this coupling is ``reciprocally sweet'', meaning that the coupling can be tuned from fully transverse (allowing coherent spin rotations) to fully longitudinal (modulating the spin resonance frequency). Based on the longitudinal coupling, the authors highlight how distant spin-spin coupling and parametrically driven spin readout can be achieved.

Effect of optimized repaired structure with a hole on crack turning and fatigue life

A method for artificially promoting crack turning is introduced. By placing a crack-absorbing hole near the patch, the dual purpose of improving the crack deflection angle and prolonging the remaining lifespan of the repaired structure was achieved. Important components behind the patch were protected as well. The influence of the location and size of a single hole on the stress concentration and crack propagation path of an optimized repaired structure was studied using the finite element method. Simultaneously, the stress influence coefficient was introduced to characterize the “attraction” effect of stress at the edge of the opening on the crack propagation path. The results showed that the optimized patch size and the existence of holes led to the deflection of cracks toward the holes and a larger residual fatigue life. When the relative hole radius was 2.22%, the relative hole axial distance was 4% and the relative hole horizontal distance was 15.56% (with a relative patch width, length, and thickness of 35.7%, 50%, and 83.3%, respectively). The deflection angle increased and the residual fatigue life improved.