Introducing a Novel Innovative Technique for the Recording and Interpretation of Dynamic Coronary Angiography.

In the study of coronary artery disease (CAD), the mechanism of plaque formation and development is still an important subject for investigation. A limitation of current coronary angiography (CAG) is that it can only show static images of the narrowing of arterial channels without identifying the mechanism of the disease or predicting its progression or regression. To address this limitation, the CAG technique has been modified. The new approach emphasizes identifying and analyzing blood flow patterns, employing methodologies akin to those used by hydraulic engineers for fluid or gas movement through domestic or industrial pipes and pumps. With the new technique, various flow patterns and arterial phenomena-such as laminar, turbulent, antegrade, retrograde, and recirculating flow and potentially water hammer shock and vortex formation-are identified, recorded, and classified. These phenomena are then correlated with the presence of lesions at different locations within the coronary vasculature. The formation and growth of these lesions are explained from the perspective of fluid mechanics. As the pathophysiology of CAD and other cardiovascular conditions becomes clearer, new medical, surgical, and interventional treatments could be developed to reverse abnormal coronary flow dynamics and restore laminar flow, leading to improved clinical outcomes.

A new device to treat ping-pong skull fractures: The hammer puller technique. A comparative analysis using a realistic simulation model.

Background: This study aims to describe a new surgical technique for the treatment of ping-pong skull fractures and to evaluate its efficacy in a realistic simulation model compared to the dissector elevation technique. Methods: A total of 64 fractures were obtained using 16 model units, each with four fractures (two frontal and two parietal). The hammer puller technique was applied for left-sided fractures and the dissector technique for right-sided fractures. The variables evaluated were fracture repair time, fracture volume, fracture corrected volume, and fracture correction percentage. Fractures were separated into groups according to the surgical technique used (hammer or dissector) and the bone fractured (frontal or parietal). Statistical analysis was performed with Jamovi® software (version 2.3) using Student's t-test. Results: A complete degree of fracture correction was achieved with both techniques, demonstrating a sufficient performance in the correction of the deformity. The hammer technique was shown to be faster in correcting frontal bone depressions with 20.1 ± 7.8 s compared to 31.3 ± 4.7 s for the dissector technique, P < 0.001. There was no statistically significant difference for parietal applications (P = 0.405). Conclusion: This study describes a new minimally invasive surgical technique for the treatment of ping-pong fractures. Comparative analysis showed that both techniques were equally effective but that the hammer puller technique was more efficient than the dissector elevation technique, especially for frontal bone fractures.

Method to determine instantaneous transient responses in pressurized pipes from transfer functions and state space for evaluation of leak signals.

This article addresses the impact of transient pressure anomalies in hydraulic systems, triggered by the opening or closing of valves or pumps, instantly disturbing the line of hydraulic gradient (LGH). This variation in pressure has significant consequences both in hydraulic and structural terms for water networks. Most of the existing techniques to detect transients in water distribution systems use asynchronous methods, generating timeless information that limits the response capacity in critical situations. Therefore, an automatic transient detection system based on the Internet of Things (IoT) is proposed, capable of identifying overpressure or underpressure pulses in soft real-time, activating alarms to facilitate decision-making. This approach helps maintain the safety of the water distribution system and prevent leaks in the network. Furthermore, a model of the transient behavior of pressure and flow is presented by linearizing the water hammer equations from the Laplace transform, thus generating a transfer function that describes the algebraic relationship between the outlet and inlet of the hydraulic system.•The transient analysis of the hydraulic system prototype underscores its high sensitivity to initial conditions, attributed to turbulence. This observation suggests the possible presence of a dynamic strange attractor related to water hammer phenomena in pressure pipes.•The methodology involving transfer functions and state-space models enables the assessment of how leaks impact the transient responses of the system, including the magnitude, duration, and frequency of disturbances generated by them.•The proposed method introduces a dynamic transfer function capable of identifying instantaneous changes over time in terms of flow and pressure.

Percutaneous distal bicortical proximal phalanx osteotomy for second toe deformities - A two-year prospective cohort study.

PURPOSE: The main purpose of our study was to evaluate satisfaction, recurrence, bone union and other complications after a minimum of two years follow-up in patients who had percutaneous claw and hammer (CHT) second toe correction utilizing a novel distal and bicortical proximal phalanx osteotomy (DBPPO). METHODS: A minimum two-year follow-up prospective cohort study was conducted on consecutive patients with symptomatic CHT deformities of the second toe corrected with percutaneous surgery. Primary outcomes included satisfaction, recurrence, bony union, and other complication rates specific to the second toe deformity correction. Secondary outcomes included Metatarsophalangeal-Interphalangeal AOFAS scale and Visual Analogue Scale (VAS). RESULTS: Between January and October 2020, 34 patients (43 feet) were clinically and radiologically evaluated pre and postoperatively at a mean of 26.6 months. Thirty-eight feet (88.4 %) were satisfied or very satisfied with their second toe deformity correction and 41 feet (95.3 %) would undergo surgery on this toe again. No deformity recurrence requiring revision was found. There were two complications (4.7 %): one toe (2.3 %) with persistent numbness and one (2.3 %) had a simple infection that resolved with oral antibiotics. All 43 s toe osteotomies demonstrated bony consolidation. Stiffness was reported in nine second toes (20.9 %), seven of them (77.8 %) having a rigid pre-operative deformity. Secondary outcomes demonstrated significant improvement in the mean ( ± standard deviation) AOFAS score which increased from 47.5 ± 17.9 preoperatively to 95.7 ± 7.7 postoperatively (p < .001). Mean VAS significantly improved from 4.9 ± 2.5 preoperatively to 0.3 ± 1.3 postoperatively (p < .001). CONCLUSION: Percutaneous treatment of claw and hammer second toe deformities utilizing a DBPPO resulted in high levels of satisfaction with bony consolidation, no recurrence and low complication rates at two years follow-up. LEVEL OF EVIDENCE: Level II - Prospective cohort study.

Dynamic characterization of water hammer in gangue fly ash slurry pipelines during valve closure.

In the process of coal-filling mining, the gangue fly-ash slurry (GFS) needs to be transported over a long distance to reach the gobs. The abrupt closure of the valve during the transportation of GFS can result in a water hammer that significantly endangers the stability and safety of the pipeline transport system. To study the fluctuations in pressure induced by abrupt closure of the valve, experiments on the rheological parameters of gangue-coal ash slurry were conducted. Transient numerical simulations were carried out using the computational fluid dynamics method for various valve closing times. The results indicate that, with the increase of slurry concentration, the yield stress of the slurry significantly increases. When the concentration exceeds 76%, the increase in yield stress reaches 38.4% and 35.1%, respectively. Upon valve closure, the internal pressure of the slurry in the pipeline exhibits periodic dynamic oscillations. As the duration of valve closure increases, the frequency of periodic water hammer events decreases. The maximum water hammer pressure caused by valve closure decreases with the increasing distance between the valve and the closure point. At the same time, the intensity of maximum water hammer pressure fluctuations increases with the increase in slurry concentration and flow velocity in the pipeline. The results can provide references for water hammer protection and pipeline selection during the transportation of backfill slurry in mining.

Suicide by a construction nail fired from a pistol.

Penetrating head injury to accomplish suicide by a non-ammunition-related projectile discharged from a nail-gun is a very rare entity. The authors describe even much rarer, and the first reported case of a suicide penetrating head injury by a construction nail discharged from a blank cartridge of a pistol. The absence of beveling and muzzle impression, the non-ejection of the discharged cartridge, and the exit of just the tip of the nail from the other side of wound were the atypical features in this firearm fatality sustained at a contact-range. The entry wound prototypes like abrasion and grease collar, and blackening were absent. An improvisation to insert a construction nail into the chamber of firearm, for utilization as a projectile was another unique highlight here. The deceased was a construction builder. Being debt-ridden, he probably could not manage to purchase even one live cartridge for his licensee pistol to bring suicidal ideation to culmination.

Between the hammer and the anvil: An unusual power hammer fatality.

Power hammers are mechanised forging devices that constitute a pivotal part of steel manufacturing. Power hammer-associated injuries are a rare occurrence. We report a noteworthy case of a 52-year-old man who sustained a high-energy penetrating injury while working with a power (counterblow) hammer. The man used a sizable disc-shaped metallic object to dislodge the forging wedged in the machine by applying the force of the striking ram on it. On impact, the object ejected and struck the man in the right lateral portion of the chest. The autopsy disclosed extensive damage to the thoracic and abdominal organs. The cause of death was opined to be exsanguination due to penetrating trauma of the heart and transection of the descending aorta. The investigation confirmed a breach of safety regulations. To the best of our knowledge, this is the first power (counterblow) hammer-related fatality in medico-legal literature.

Ultrasonography-Based Quantitative Evaluation of Second Metatarsophalangeal Joint Instability in Female Patients With Hallux Valgus.

BACKGROUND: Patients with moderate to severe hallux valgus (HV) sometimes exhibit second metatarsophalangeal (MTP) joint dislocation. Second MTP joint instability due to plantar plate (PP) injury has been suggested as one of the causes. However, there have been no reports that quantitatively evaluate this instability. This study aimed to evaluate second MTP joint instability in patients with HV without dislocation via ultrasonography and investigate its relationship with the presence of PP injury or foot form. METHODS: Between May 2018 and July 2023, symptomatic female patients with HV without any lesser toe deformity were included in this study. Second MTP joint instability was defined as the dorsal displacement ratio (DDR) of the passively subluxated proximal phalangeal articular surface on the metatarsal head articular surface. The presence of PP injury was assessed using ultrasonography. Foot "form" was determined by measuring standard foot bony angles on weight-bearing foot-ankle radiographs. The relationship between DDR or PP injury and radiographic measurements was investigated. RESULTS: Sixty-four patients (100 feet) were included. The average DDR of the second MTP joint in patients with HV without dislocation was 35.7%. There was an increase in the probability of PP injury, above a cutoff DDR value r of 35.4% (area under the curve = 0.712). The sensitivity, specificity, positive predictive value, and negative predictive value for the presence of PP injury based on this cutoff level were 63.9%, 74.4%, 79.6%, and 56.9%, respectively. Metatarsalgia was reported in 21 feet (21.0%), of which 15 feet (71.4%) showed PP injury. An increase in DDR was weakly associated with increased metatarsus adductus angle and decreased second metatarsal height. CONCLUSION: In female patients with HV without second MTP dislocation, we found ultrasonographic evidence of second MTP plantar plate injury and joint instability to be a relatively common finding with a high prevalence in those with localized metatarsalgia. LEVEL OF EVIDENCE: Level II, development of diagnostic criteria based on consecutive patients.

Experimental Study on Dynamic Characteristics of Damaged Post-Tensioning Concrete Sleepers Using Impact Hammer.

Concrete sleepers in operation are commonly damaged by various internal and external factors, such as poor materials, manufacturing defects, poor construction, environmental factors, and repeated loads and driving characteristics of trains; these factors affect the vibration response, mode shape, and natural frequency of damaged concrete sleepers. However, current standards in South Korea require only a subjective visual inspection of concrete sleepers to determine the damage degree and necessity of repair or replacement. In this study, an impact hammer test was performed on concrete sleepers installed on the operating lines of urban railroads to assess the field applicability of the modal test method, with the results indicating that the natural frequency due to concrete sleeper damage was lower than that of the undamaged state. Furthermore, the discrepancy between the simulated and measured natural frequencies of the undamaged concrete sleeper was approximately 1.87%, validating the numerical analysis result. The natural frequency of the damaged concrete sleepers was lower than that of the undamaged concrete sleeper, and cracks in both the concrete sleeper core and the rail seat had the lowest natural frequency among all the damage categories. Therefore, the damage degrees of concrete sleepers can be quantitatively estimated using measured natural-frequency values.

Sudden pump stop may cause air release in oxygenators, 'The Hammer Effect ': An in vitro evaluation.

BACKGROUND: Oxygenators, as used in cardiopulmonary bypass (CPB) circuits, are components with good air removal properties. However, under some conditions the semipermeable characteristics of hollow fibers allow air to accidentally enter the blood side of the CPB circuit. This may occur when a fluid in motion is stopped suddenly by which the rapid change in momentum may cause a relative negative pressure drop, the so-called hammer effect. The hammer effect is not yet described in literature related to CPB. The aim of this in vitro study was to reproduce the hammer effect. METHODS: The in vitro setup consisted of a CPB circuit with a fully occluded roller pump and one of four test oxygenators. The hammer test was performed by a sudden pump stop. The pressure wave was measured and after the test the residual air present in the oxygenator was forced into the arterial line and measured with a bubble detector. RESULTS: We showed that a sudden pump stop could lead to the hammer effect, represented as a relative negative pressure drop in the arterial line. This hammer effect resulted in air release through the semipermeable fibers as we showed in two of the four tested brands of oxygenators. CONCLUSIONS: We conclude that the hammer effect may occur before connection of the CPB system to the patient, and this may result in air release into the arterial blood side of the oxygenator. The hammer effect can be caused by clamping of the tubing in combination with a centrifugal pump, or by suddenly stopping the roller pump. With this study we would like to raise awareness of the hammer effect.

Evaluation of Pipe Thickness by Magnetic Hammer Test with a Tunnel Magnetoresistive Sensor.

A new nondestructive inspection method, the magnetic hammer test (MHT), which uses a compact and highly sensitive tunnel magnetoresistance (TMR) sensor, is proposed. This method complements the magnetic flux leakage method and eliminates the issues of the hammer test. It can therefore detect weak magnetic fields generated by the natural vibration of a pipe with a high signal-to-noise ratio. In this study, several steel pipes with different wall thicknesses were measured using a TMR sensor to demonstrate the superiority of MHT. The results of the measurement show that wall thickness can be evaluated with the accuracy of several tens of microns from the change in the natural vibration frequency of the specimen pipe. The pipes were also inspected underwater using a waterproofed TMR sensor, which demonstrated an accuracy of less than 100 µm. The validity of these results was by simulating the shielding of magnetic fields and vibration of the pipes with the finite element method (FEM) analysis. The proposed noncontact, fast, and accurate method for thickness testing of long-distance pipes will contribute to unmanned, manpower-saving nondestructive testing (NDT) in the future.

Improvement of the Technology of Precision Forging of Connecting Rod-Type Forgings in a Multiple System, in the Aspect of the Possibilities of Process Robotization by Means of Numerical Modeling.

The study refers to the application of numerical modeling for the improvement of the currently realized precision forging technology performed on a hammer to produce connecting rod forgings in a triple system through the development of an additional rolling pass to be used before the roughing operation as well as preparation of the charge to be held by the robot's grippers in order to implement future process robotization. The studies included an analysis of the present forging technology together with the dimension-shape requirements for the forgings, which constituted the basis for the construction and development of a thermo-mechanical numerical model as well as the design of the tool construction with the consideration of the additional rolling pass with the use of the calculation package Forge 3.0 NxT. The following stage of research was the realization of multi-variant numerical simulations of the newly developed forging process with the consideration of robotization, as a result of which the following were obtained: proper filling of the tool impressions (including the roller's impression) by the deformed material, the temperature distributions for the forging and the tools as well as plastic deformations (considering the thermally activated phenomena), changes in the grain size as well as the forging force and energy courses. The obtained results were verified under industrial conditions and correlated with respect to the forgings obtained in the technology applied so far. The achieved results of technological tests confirmed that the changes introduced into the tool construction and the preform geometry reduced the diameter, and thus also the volume, of the charge as well as provided a possibility of implementing robotization and automatization of the forging process in the future. The obtained results showed that the introduction of an additional rolling blank resulted in a reduction in forging forces and energy by 30% while reducing the hammer blow by one. Attempts to implement robotization into the process were successful and did not adversely affect the geometry or quality of forgings, increasing production efficiency.

Performance Assessment of Pneumatic-Driven Automatic Valves to Improve Pipeline Fault Detection Procedure by Fast Transient Tests.

The use of fast transients for fault detection in long transmission networks makes the generation of controlled transients crucial. In order to maximise the information that can be extracted from the measured pressure time history (pressure signal), the transients must meet certain requirements. In particular, the manoeuvre that generates the transient must be fast and repeatable, and must produce a pressure wave that is as sharp as possible, without spurious pressure oscillations. This implies the use of small-diameter valves and often pneumatically operated automatic valves. In the present work, experimental transient tests are carried out at the Water Engineering Laboratory (WEL) of the University of Perugia using a butterfly valve and a ball pneumatic-driven valve to generate pressure waves in a pressurised copper pipe. A camera is used to monitor the valve displacement, while the pressure is measured by a pressure transducer close to the downstream end of the pipe where the pneumatic valve is installed. The experimental data are analysed to characterise the valve performance and to compare the two geometries in terms of valve closing dynamics, the sharpness of the generated pressure wave and the stability of the pressure time history. The present work demonstrates how the proposed approach can be very effective in easily characterising the transient dynamics.

Fabrication of nano-hammer shaped CuO@HApNWs for catalytic degradation of tetracycline.

With widespread and excessive use of antibiotics in medicine, poultry farming, and aquaculture, antibiotic residues have become a significant threat to both eco-environment and human health. In this paper, using hydroxyapatite nanowires (HApNWs) as an ecologically compatible carrier, a novel nano-hammer shaped conjunction with HApNW conjugating CuO microspheres (CuO@HApNWs) was successfully synthesized by in-situ agglomeration method. The catalytic degradation performance of the nano-hammer shaped CuO@HApNWs with Fenton-like activation was investigated by using tetracycline (TC) as a representative antibiotic pollutant. Remarkably, it exhibited excellent catalytic activity, which the removal rate of TC got to 92.0% within 40 min, and the pseudo-second-order reaction kinetic constant was 18.33 × 10-3 L mg-1·min-1, which was 26 times and 5 times than that of HApNWs and CuO, respectively. Furthermore, after recycling 6 times, the degradation efficiency of TC still remained above 85 %. Based on radical scavenger tests and electron paramagnetic resonance (EPR) spectroscopy, it demonstrated that the excellent activity of CuO@HApNWs was mainly attributed to the fact that Fenton-like activation promotes the circulation of Cu2+ and Cu+, the generated main active oxygen species (•OH and O2-•) achieve efficient degradation of TC. In summary, the nano-hammer shaped CuO@HApNWs could be in-situ synthesed, and used as an eco-friendly Fenton-like catalyst for effectively catalytic degradation of organic pollutants, which has great potential for wastewater treatment.

Multimodality imaging review of ulnar nerve pathologies.

The ulnar nerve is the second most commonly entrapped nerve after the median nerve. Although clinical evaluation and electrodiagnostic studies remain widely used for the evaluation of ulnar neuropathy, advancements in imaging have led to increased utilization of these newer / better imaging techniques in the overall management of ulnar neuropathy. Specifically, high-resolution ultrasonography of peripheral nerves as well as MRI has become quite useful in evaluating the ulnar nerve in order to better guide treatment. The caliber and fascicular pattern identified in the normal ulnar nerves are important distinguishing features from ulnar nerve pathology. The cubital tunnel within the elbow and Guyon's canal within the wrist are important sites to evaluate with respect to ulnar nerve compression. Both acute and chronic conditions resulting in deformity, trauma as well as inflammatory conditions may predispose certain patients to ulnar neuropathy. Granulomatous diseases as well as both neurogenic and non-neurogenic tumors can also potentially result in ulnar neuropathy. Tumors around the ulnar nerve can also lead to mass effect on the nerve, particularly in tight spaces like the aforementioned canals. Although high-resolution ultrasonography is a useful modality initially, particularly as it can be helpful for dynamic evaluation, MRI remains most reliable due to its higher resolution. Newer imaging techniques like sonoelastography and microneurography, as well as nerve-specific contrast agents, are currently being investigated for their usefulness and are not routinely being used currently.

Reconstruction of the ulnar artery in Guyon's canal with an arterial graft: Anatomical study.

Ulnar artery thrombosis in Guyon's canal can lead to vascular insufficiency in the fingers. The recommended treatment is resection and reconstruction of the pathological area. A bypass may be necessary, which may be venous or arterial. Arterial bypasses have better long-term patency; however, they are a source of donor-site complications. We carried out an anatomical study on 11 upper limbs and 7 lower limbs from cadavers to identify a technically accessible arterial graft, of a diameter suitable for bypassing the ulnar artery in Guyon's canal and with acceptable scar sequelae (few predicted postoperative complications, discreet size and/or location of scar). Three grafts were considered: anterior interosseous artery, radial recurrent artery and descending genicular artery. The various grafts were dissected and harvested from cadaver specimens, then their lengths and diameters were measured. The diameter of the candidate grafts was compared to the diameter of the distal ulnar artery. The diameter of the descending genicular artery matched the ulnar artery better than the radial recurrent artery or the anterior interosseous artery (103% vs 44% and 67%, respectively). Mean graft length was 6.6 cm. The anatomical configuration of the descending genicular artery allowed Y-shaped bypasses to be performed. Harvesting this artery appears to cause little damage and allows bypasses up to 6 cm to be performed. Despite its smaller diameter making it necessary to perform a microvascular size adjustment, the anterior interosseous artery is a candidate graft because it is long enough (119 mm) and located near the surgical site. LEVEL OF EVIDENCE: V.

The use of an Intra-medullary fusion system in hammer toe surgery; mid-term follow-up.

Objectives: To assess the efficacy of a new hammer-toe locking fusion system. METHODS: The retrospective study was conducted at Kutahya Evliya Çelebi Education and Research Hospital, and comprised data from March 2014 to January 2017 of patients of either gender with hammer toe deformity. The American Orthopaedic Foot and Ankle Society and visual analogue scale scoring systems were used. Radiological evaluation was also used to determine the lateral interphalangeal angle measurements. All patients were subjected to hammer toe surgery using new two-block interlocking fusion system, and were followed up for about 2 years. SPSS 25.0 for windows was used for analysis. RESULTS: According to gender, 13(65%) of patients were female and 7(35%) of patients were male. The overall mean age was 51.5±16.31 years (range: 20-72 years). Of all the surgeries, 9(45%) were performed on the right foot, and 11(55%) on the left foot. The follow-ups ranged 21-32 months. Compared to baselines values, American Orthopaedic Foot and Ankle Society scale and visual analogue scale scores significantly improved post intervention (p<0.05). CONCLUSIONS: Significantly favourable outcomes were noted, indicating the efficacy of the fusion process.

Fistulized Pseudoaneurysm Associated with Hypothenar Hammer Syndrome to the Skin in a 12-Year-Old Patient: A Case Report.

In this case, we present a condition where the extension of the hamate hook in the Guyon canal can damage the ulnar artery or its branches, leading to the development of an aneurysm or pseudoaneurysm. The patient, a 12-year-old female, presented to our clinic with a complaint of an uncontrolled palm lump that has been growing for several months and began to bleed in a pulsatile manner after trauma. She was an amateur volleyball player who trained twice weekly for two hours. Color Doppler ultrasound examination revealed a 1.1×0.8 cm pseudoaneurysm in a branch of the ulnar artery. Aneurysmectomy and primary repair were performed. Timely diagnosis and treatment planning are crucial for ulnar artery pseudoaneurysms or aneurysms to prevent ischemic events in a later period.

Noise Exposure and Hearing Loss among Workers at a Hammer Forge Company.

The National Institute for Occupational Safety and Health (NIOSH) evaluated continuous and impact noise exposures and hearing loss among workers at a hammer forge company. Full-shift personal noise exposure measurements were collected on forge workers across 15 different job titles; impact noise characteristics and one-third octave band noise levels were assessed at the forge hammers; and 4,750 historic audiometric test records for 483 workers were evaluated for hearing loss trends. Nearly all workers' noise exposures exceeded regulatory and/or recommended exposure limits. Workers working in jobs at or near the hammers had full-shift time-weighted average noise exposures above 100 decibels, A-weighted. Impact noise at the hammers reached up to 148 decibels. Analysis of audiometric test records showed that 82% of workers had experienced a significant threshold shift, as defined by NIOSH, and 63% had experienced a standard threshold shift, as defined by the Occupational Safety and Health Administration (OSHA). All workers with an OSHA standard threshold shift had a preceding NIOSH significant threshold shift which occurred, on average, about 7 years prior. This evaluation highlights forge workers' exposures to high levels of noise, including impact noise, and how their hearing worsened with age and length of employment.

Did Early Pleistocene hominins control hammer strike angles when making stone tools?

In the study of Early Pleistocene stone artifacts, researchers have made considerable progress in reconstructing the technical decisions of hominins by examining various aspects of lithic technology, such as reduction sequences, hammer selection, platform preparation, core management, and raw material selection. By comparison, our understanding of the ways in which Early Pleistocene hominins controlled the delivery and application of percussive force during flaking remains limited. In this study, we focus on a key aspect of force delivery in stone knapping, namely the hammerstone striking angle (or the angle of blow), which has been shown to play a significant role in determining the knapping outcome. Using a dataset consists of 12 Early Pleistocene flake assemblages dated from 1.95 Ma to 1.4 Ma, we examined temporal patterns of the hammer striking angle by quantifying the bulb angle, a property of the flake's Hertzian cone that reflects the hammer striking angle used in flake production. We further included a Middle Paleolithic flake assemblage as a point of comparison from a later time period. In the Early Pleistocene dataset, we observed an increased association between the bulb angle and other flake variables related to flake size over time, a pattern similarly found in the Middle Paleolithic assemblage. These findings suggest that, towards the Oldowan-Acheulean transition, hominins began to systematically adjust the hammer striking angle in accordance with platform variables to detach flakes of different sizes more effectively, implying the development of a more comprehensive understanding of the role of the angle of blow in flake formation by ∼1.5 Ma.