Modeling and optimization of a modified iron-yoked electromagnetic propulsion system using the gravitational search algorithm.

Potential uses for electromagnetic launchers in defense systems, space exploration, and transportation have recently emerged. In addition, this accelerator has many applications, such as deploying small satellites into low-earth orbit and accelerating high-speed trains (e.g., bullet trains and Hyperloop) with a low-cost propulsion system instead of expensive linear motors, particularly in space applications. Therefore, the full capability and optimization of these launchers' efficiency are still required. Therefore, this paper focuses on presenting a new design to decrease the coil's magnetic circuit reluctance and boost the magnetic flux lines by adding a laminated iron yoke surrounding the coil. This design makes the inductance value of the iron-yoked accelerator twice the inductance in case of the absence of the iron-yoke at its peak. Additionally, the initial inductance of the iron-yoked accelerator is approximately 65% higher than that of the coil without the iron yoke. Consequently, the modified design proposed an efficiency of 17.5%, which represents a 60% improvement over the efficiency of the regular accelerator. In addition, the introduced design eliminates the suck-back force using a fast-switching device (IGBT) to switch the coil off when the projectile reaches half of the coil. Moreover, a mathematical model for the iron-yoked accelerator is built on MATLAB Simulink and validated experimentally. An artificial intelligence optimization technique, the gravitational search algorithm (GSA), is used to optimize the accelerator parameters, such as the number of turns, capacitor value, and capacitor voltage. Finally, the experimental evaluation of the GSA-optimized system demonstrated an additional 15% enhancement in efficiency, bringing the total efficiency to 20%.

Effects of Processing Method and Parameters on the Wall Thickness of Gas-Projectile-Assisted Injection Molding Pipes.

Gas-Projectile-Assisted Injection Molding (G-PAIM) is a new injection molding process derived from the Gas-Assisted Injection Molding (GAIM) process by introducing a projectile to it. In this study, the short-shot method and the overflow method of both the G-PAIM and GAIM processes were experimentally compared and investigated in terms of the wall thickness of the pipes and its uniformity. The results showed that the wall thickness of the G-PAIM molded pipe was thinner and more uniform than that of the GAIM molded pipe, and the wall thickness of the pipe molded by the Gas-Projectile-Assisted Injection Molding Overflow (G-PAIM-O) process was the most uniform. For the G-PAIM-O process, the influence of processing parameters, including melt temperature, gas injection delay time, gas injection pressure, melt injection pressure and mold temperature, on the wall thickness and uniformity of the G-PAIM-O pipes were studied via the single-factor experimental method. It was found that the effects of gas injection delay time and gas injection pressure on the wall thickness of the G-PAIM-O pipes were relatively significant. The wall thickness of the pipes increased with the increase in gas injection delay time and decreased with the increase in gas injection pressure. The melt temperature, melt injection pressure and mold temperature had little effect on the wall thickness of the G-PAIM-O pipes. In general, the wall thickness uniformity of the G-PAIM-O pipes was slightly affected by these processing parameters.

Additive Manufacturing and Combustion Characteristics of Polyethylene Oxide/Aluminum/Copper Oxide-Based Energetic Nanocomposites for Enhancing the Propulsion of Small Projectiles.

The application of nanoscale energetic materials (nEMs) composed of metal and oxidizer nanoparticles (NPs) in thermal engineering systems is limited by their relatively high sensitivity and complex three-dimensional (3D) formability. Polymers can be added to nEMs to lower the sensitivity and improve the formability of 3D structures. In this study, the effect of the addition of polyethylene oxide (PEO; polymer) on the combustion characteristics of aluminum (Al; fuel)/copper oxide (CuO; oxidizer)-based nEMs is investigated. With an increase in the PEO content, the resulting PEO/nEM composites are desensitized to relatively high electrical spark discharges. However, the maximum explosion-induced pressure decreases significantly, and the combustion flame fails to propagate when the PEO content exceeds 15 wt.%. Therefore, the optimal PEO content in a nEM matrix must be accurately determined to achieve a compromise between sensitivity and reactivity. To demonstrate their potential application as composite solid propellants (CSPs), 3D-printed disks composed of PEO/nEM composites were assembled using additive manufacturing. They were cross-stacked with conventional potassium nitrate (KNO3)/sucrose (C12H22O11)-based disk-shaped CSPs in a combustion chamber of small rocket motors. Propulsion tests indicated that the specific impulse of KNSU/PEO/nEM (nEMs: 3.4 wt.%)-based CSPs was at a maximum value, which is approximately three times higher than that of KNSU CSPs without nEMs. This suggests that the addition of an optimized amount of polymer to nEMs is beneficial for various CSPs with compromised sensitivity and reactivity and excellent 3D formability, which can significantly enhance the propulsion of small projectiles.

Fijadores externos para tratar fractura mandibular causada por herida de arma de fuego. Reporte de caso / External fxators as treatment for mandibular fracture caused by gunshot wound. Case report

Introducción: las heridas por proyectil de arma de fuego en la región craneofacial provocan daños funcionales devastadoras y deformidades estéticas, que se suman al trauma psicológico al momento del regreso a la vida cotidiana de un paciente. Por esta razón, la reconstrucción adecuada es esencial para una rehabilitación integral. La fijación externa es un método de reducción cerrada de fracturas que implica el uso de tornillos para manipular segmentos sueltos de hueso, que luego se fijan mediante conexiones externas. Es importante recalcar que las fracturas mandibulares causadas por proyectil de arma de fuego son un reto para este tipo de tratamiento. Objetivo: presentar el caso de un paciente con fractura mandibular por proyectil de arma de fuego tratado con fijadores externos y revisión de la literatura sobre este tipo de tratamiento. Caso clínico: paciente masculino de 19 años que presentó fractura de rama mandibular izquierda causado por proyectil de arma de fuego; la fractura se manejó mediante la colocación de fijación intermaxilar con arcos barra tipo Erich y fijación externa durante 3 meses. Como parte del resultado, el paciente presentó una correcta oclusión dentaria y mantiene sus movimientos mandibulares sin ninguna limitación. Esto demuestra que la reducción cerrada y fijación externa debe mantenerse en el arsenal terapéutico debido a sus adecuados resultados comprobados en la literatura y en este caso. Ahora bien, aunque la reducción abierta y fijación interna con material de osteosíntesis hace parte del manejo idóneo para todo tipo de fractura, todos los casos requieren ser individualizados.

Background: wounds from a frearm projectile in the craniofacial region cause devastating functional damage and aesthetic deformities, along with psychological trauma when returning to daily life. This is why proper reconstruction is essential for comprehensive rehabilitation. External fxation is a method of closed fracture reduction that involves the use of screws to manipulate loose segments of bone that are then fxed using external connections. Objective: to present the case of a patient with a mandibular fracture caused by a frearm projectile treated with external fixators and review the literature. Clinical case: a 19-year-old male patient who presented a fracture of the left mandibular ramus caused by a frearm projectile, the fracture was managed by placing intermaxillary fxation with Erich-type bar arches and external fixation for 3 months. The patient presented a correct dental occlusion and maintains his mandibular movements without any limitation. Conclusion: mandibular fractures caused by frearm projectiles are a challenge for treatment. Open reduction and internal fixation with osteosynthesis material is the ideal management for all types of fractures, however, all cases must be individualized, and it must be considered that closed reduction and external fxation must remain in our therapeutic arsenal due to their adequate results verifed in the literature and in our case.

Heridas atípicas producidas por proyectil de arma de fuego Reporte de caso / Atypical wounds caused by firearm projectile Case report

Resumen Las heridas por proyectil de arma de fuego se definen como los efectos que producen sobre el organismo los disparos realizados con armas cargadas de proyectiles o diversos tipos de pólvora u otros explosivos. La valoración médico legal en estos casos, en personas vivas, se realiza en la Sección Clínica Médico Forense del Departamento de Medicina Legal del Organismo de Investigación Judicial, esta incluye la historia médico legal, el examen físico, el análisis de documentos médicos aportados, pericias conexas efectuadas y revisión de bibliografía, esto para tener todos los elementos de juicio que permitan realizar un análisis objetivo y basado en la evidencia científica, y así poder responder a las interrogantes de la Autoridad Judicial. El presente artículo abarca algunos de los aspectos principales a tomar en cuenta ante hallazgos atípicos de los orificios de entrada y salida de los proyectiles, mediante la presentación y abordaje de un caso clínico.

Abstract Firearm projectile injuries are defined as the effects produced on the body by shots fired with weapons loaded with projectiles or various types of gunpowder or other explosives. The legal medical assessment in these cases, in living persons, is carried out in the Forensic Medical Clinical Section of the Department of Legal Medicine of the Organismo de Investigación Judicial, this includes the legal medical history, physical examination, analysis of medical documents provided, expert carried out and bibliography review, this to have all the elements of judgment that allow an objective analysis based on scientific evidence, and thus be able to answer the questions of the Judicial Authority. This article covers some of the main aspects to be considered when faced with atypical findings of the entry and exit holes of the projectiles, through the presentation and approach of a clinical case. Ver bases de datos

Self-Healability of Poly(Ethylene-co-Methacrylic Acid): Effect of Ionic Content and Neutralization.

Self-healing polymers such as poly(ethylene-co-methacrylic acid) ionomers (PEMAA) can heal themselves immediately after a projectile puncture which in turn lowers environmental pollution from replacement. In this study, the thermal-mechanical properties and self-healing response of a library of 15 PEMAA copolymers were studied to understand the effects of the ionic content (Li, Na, Zn, Mg) and neutralization percentage (13 to 78%) on the results. Differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and tensile testing were used to study the thermo-mechanical properties of PEMAA copolymers while the self-healing response was studied using the projectile test. Puncture sites were observed using scanning electron microscopy (SEM) and the healing efficiency was quantitatively measured using the water leakage test. Five different self-healing responses were observed and correlated to ionic content and neutralization. At high neutralization, divalent neutralizing ions (Zn and Mg) that have stronger ionic interactions exhibited brittle responses during projectile testing. PEMAA samples neutralized with Mg and Li at low concentrations had a higher healing efficiency than PEMAA samples neutralized with Zn and Na at low neutralization. The PEMAA copolymers with higher tensile stress and two distinct peaks in the graph of loss factor versus temperature that indicate the presence of sufficient ionic aggregate clusters had improved healing efficiency. By increasing the neutralization percentage from 20% to 70%, the tensile strength and modulus of the samples increased and their self-healability generally increased. Among the investigated samples, the copolymer with ~50% neutralization by Li salt showed the highest healing efficiency (100%). Overall, the strength and elastic response required for successful self-healing responses in PEMAA copolymers are shown to be governed by the choice of ion and the amount of neutralization.

Neurosurgery during the Greco-Italian War (World War II): the management of war-related head injuries at the Italian field hospital of Sinanaj in Albania.

During the Greco-Italian War (World War II [WWII], 1940-1941), an Italian field hospital was set up in Sinanaj, Albania. The hospital's military surgeons carefully collected information about the characteristics and management of patients with war-related injuries. In 1942, they published a detailed report, with a section dedicated to the management of war-related head injuries. The aim of this report is to analyze that section, to describe the characteristics and neurosurgical management of war-related head injuries, and to depict the status of war neurosurgery in the Royal Italian Army during WWII. The analysis revealed that, during the Greco-Italian War (November 1940-April 1941), 149 patients with war-related head injuries were admitted to the Sinanaj hospital, and 48 patients underwent surgery. Head injuries were caused by bomb fragments in 126 patients, bullets in 5 patients, and other causes (falls from height, vehicle accidents, or rock fragments) in 18 patients. Six patients (12.5%) died after surgery. Before surgery, patients underwent resuscitation with blood transfusions and fluid. Preoperatively, a plain head radiograph was usually acquired to locate metallic and bone fragments. The surgical technique consisted of craniotomy or craniectomy, aggressive debridement of metallic and bone fragments, and watertight dural closure. Surgical drainage, overall aseptic technique, serial spinal taps, and perioperative antibiotics were used to prevent infections. The surgical aims and technique used by the Italian surgeons for the management of head injuries were similar to those of the Allied surgeons during WWII. Operative mortality was also comparable. Although the surgical technique for war-related head injuries has evolved since WWII, many aspects of the technique used by the Italian and Allied surgeons during WWII are still in the standard of care today.

Thermal Energy Analysis of Projectiles during Ricochetting Using a Thermal Camera.

This paper presents the results of a study of the hazards of ground ignition and/or explosion when various small-calibre projectiles struck various solid materials placed on a test stand in environments at risk of ignition (fire) or explosion (ricochets and projectile penetration of obstacles). For projectile ricochetting tests, the following were used: an armour plate, concrete, sidewalk and granite slabs, etc., and various small-calibre projectiles: 7.62 × 51 mm SWISS PAP, 7.62 × 51T, 7.62 × 51 mm M80, 7.62 × 54R B-32, 7.62 × 54R LPS and .308 Win. Norma Ecostrike. Projectiles impacts were recorded with a high-speed camera (50,400 fps) and thermal cameras (660 fps) and (2615 fps). The ignition capability of solid flammable materials during projectile ricochetting was studied, and the temperatures and surface areas of isotherms were measured as a function of time. From the spherical distribution of thermal energy radiation in space, their volumes, masses of air occupying the studied area, masses of projectile disintegrating into fragments (after impact), thermal energies during projectile ricochetting, histograms of area temperatures and temperatures were calculated. This energy was compared with the minimum ignition energy of the selected gases and liquid vapours, and the ignition temperature were determined. The probabilities of some of the selected gases and liquid vapours which can ignite or cause an explosion were determined. The thermal energies of the 7.62 × 54R B-32 (3400-9500 J) and 7.62 × 51T (2000-3700 J) projectiles ricochetting on the Armox 600 plate was sufficient to ignite (explode) propane-butane gas. The thermal energy of 7.62 × 54R B-32 projectiles ricochets on the non-metallic components (800-1200 J) was several times lower than that of projectiles ricochets on an Armox 600 plate (3400-9500 J). This is due to the transfer of much of the kinetic energy to the crushing of these elements.

Lesión del nervio ciático mayor por proyectil de escopeta / Lesion of the major sciatic nerve due to a shotgun projectile

Se describe el caso clínico de un paciente de 26 años de edad, atendido en la consulta de Ortopedia y Traumatología del Centro de Diagnóstico Integral Salvador Allende de Caracas, en la República Bolivariana de Venezuela, quien desde hacía 6 meses había recibido un disparo de escopeta en la cara posterior de ambos muslos. Esta vez acudió a consulta con dolor intenso en el miembro inferior izquierdo, sobre todo por debajo de la rodilla, acompañado de parestesias en la zona de inervación de ambas ramas de bifurcación del nervio ciático. Se pudo comprobar que el joven presentaba múltiples impactos de proyectiles en la cara posterior de ambos muslos y marcha claudicante. Los estudios radiográficos confirmaron la presencia de 8 proyectiles, 2 en el muslo derecho y 6 en el izquierdo. En la vista lateral se observó que uno de ellos se encontraba a una profundidad que se correspondía con la región anatómica del nervio ciático izquierdo. Para la intervención quirúrgica se utilizó anestesia local, sedación y un intensificador de imágenes. Con la cooperación del paciente se pudo extraer el proyectil alojado en el epineuro del ciático sin complicaciones. A los 3 meses habían desaparecido las molestias y pudo reincorporarse a sus actividades habituales.

The case report of a 26 years patient is described. He was assisted in the Orthopedics and Traumatology Service of Salvador Allende Integral Diagnostic Center from Caracas, in the Bolivian Republic of Venezuela who had received a shotgun shot in the posterior face of both thighs 6 months ago. This time he went to visit the doctor with intense pain in the left inferior member, mainly below the knee, accompanied by paresthesias in the innervation area of both bifurcation branches of the sciatic nerve. It could be demonstrated that the young man presented multiple projectile impacts in the posterior face of both thighs and hesitating gait. The radiographic studies confirmed the presence of 8 projectiles, two in the right thigh and 6 in the left one. In the lateral view it was observed that one of them was at a depth that matched with the anatomical region of the left sciatic nerve. Local anesthesia, sedation and an images intensifier were used for the operation. The projectile located in the epineurium of the sciatic nerve could be removed with the patient cooperation without complications. After 3 months the discomfort had disappeared and he could return to his usual activities.

Effect of Heat Input on the Ballistic Performance of Armor Steel Weldments.

The purpose of this study is to examine the projectile penetration resistance of the base metal and heat-affected zones of armor steel weldments. To ensure the proper quality of armor steel welded joints and associated ballistic protection, it is important to find the optimum heat input for armor steel welding. A total of two armor steel weldments made at heat inputs of 1.29 kJ/mm and 1.55 kJ/mm were tested for ballistic protection performance. The GMAW welding carried out employing a robot-controlled process. Owing to a higher ballistic limit, the heat-affected zone (HAZ) of the 1.29 kJ/mm weldment was found to be more resistant to projectile penetration than that of the 1.55 kJ/mm weldment. The ballistic performance of the weldments was determined by analyzing the microstructure of weldment heat-affected zones, the hardness gradients across the weldments and the thermal history of the welding heat inputs considered. The result showed that the ballistic resistance of heat affected zone exist as the heat input was decreased on 1.29 kJ/mm. It was found that 1.55 kJ/mm does not have ballistic resistance.

Fracturas Mandibulares Conminutadas por Impacto de Proyectil Balístico: resultados Clínicos de Tratamiento Con Método de Fijación Alternativo / Mandibular Fractures Comminuted by Ballistic Projectile Impact: clinical Results of Treatment with Alternative Fixation Method

Las fracturas mandibulares conminutadas por impacto de proyectil balístico son un desafío terapéutico debido a la presencia de múltiples fragmentos óseos y el compromiso a nivel de periostio, plano muscular y mucoso. Su tratamiento inicial requiere de una estabilización de las urgencias médico - quirúrgicas y posteriormente tratar los segmentos óseos fracturados. La fijación externa con tutores mandibulares permite estabilizar los segmentos mandibulares de forma cerrada manteniendo así la viabilidad de los fragmentos sin interrumpir su suministro de sangre. El objetivo de este trabajo es presentar los resultados post operatorios obtenidos en tres casos clínicos de pacientes con diagnóstico de fractura mandibular conminutada por trauma por impacto de proyectil balístico, tratados por un método alternativo a los tutores de fijación externa convencional.

Comminuted mandibular fractures from ballistic missile impact are a therapeutic challenge due to the presence of multiple bone fragments and the involvement of periosteum, muscle and mucous membrane. Their initial treatment requires emergency medical and surgical stabilization and later treatment of the fractured bone segments. External fixation with mandibular stakes makes it possible to stabilize the mandibular segments in a closed manner, thus maintaining the viability of the fragments without interrupting their blood supply. The aim of this work is to present the post-surgical results obtained in three clinical cases of patients with diagnosis of comminuted mandibularfracture by ballistic missile impact, treated by an alternative method to the conventional external fixation tutors.

"Bone-shot fracture" - An unusual iliac wing fracture caused by a projectile of autologous bone fragment. A case report.

CASE: A young adult male sustained a high-energy crash suffering multiple injuries including a comminuted right femoral shaft fracture and an ipsilateral iliac wing fracture. The iliac fracture was caused by a femoral fragment which was projected and pierced the iliac wing. The patient underwent surgery with retrieval of the femoral fragment and fixation of the iliac and femoral fractures. The lesions healed uneventfully. CONCLUSION: This is the first reported case of an iliac fracture caused by a projectile of autologous bone. High-energy trauma may present unusual or never seen injury patterns to the trauma surgeon.

Perforation of Double-Spaced Aluminum Plates by Reactive Projectiles with Different Densities.

Perforation behavior of 3 mm/3 mm double-spaced aluminum plates by PTFE/Al/W (Polytetrafluoroethylene/Aluminum/Tungsten) reactive projectiles with densities ranging from 2.27 to 7.80 g/cm3 was studied experimentally and theoretically. Ballistic experiments show that the failure mode of the front plate transforms from petalling failure to plugging failure as projectile density increases. Theoretical prediction of the critical velocities for the reactive projectiles perforating the double-spaced plates is proposed, which is consistent with the experimental results and well represents the perforation performance of the projectiles. Dimensionless formulae for estimating the perforation diameter and deflection height of the front plates are obtained through dimensional analysis, indicating material density and strength are dominant factors to determine the perforation size. High-speed video sequences of the perforation process demonstrate that high-density reactive projectiles make greater damage to the rear plates because of the generation of projectile debris streams. Specifically, the maximum spray angle of the debris streams and the crater number in the debris concentration area of the rear plate both increase with the projectile density and initial velocity.

Migración de proyectil de arma de fuego en vía urinaria: Reporte de un caso con enfoque Médico Legal / Migration of a bullet from a gunshot wound in the urinary tract: A case report with Legal Medicine approach

Resumen La migración de un proyectil de arma de fuego por la vía urinaria y expulsión espontánea del mismo por el meato urinario es un hecho infrecuente. Se presenta el caso de un masculino de 24 años de edad, quien sufrió herida por proyectil de arma de fuego con orificio de entrada en el muslo derecho, sin orifico de salida, se observó mediante una radiografía el proyectil alojado en la pelvis, dos meses y medio después el paciente se presenta al servicio de emergencias con el proyectil ubicado en la uretra, el cual se extrajo por el meato urinario sin complicaciones. Se hizo una revisión de la literatura sobre migración de proyectiles de armas de fuego.

Abstract Migration of a bullet through the urinary tract and spontaneous expulsion through the urinary meatus is an uncommon event. We present a case of a 24-year-old male, who suffered a gunshot wound with an entry hole in the right thigh, without an exit hole, and the projectile lodged in the pelvis was observed by radiography, two months and a half later the patient presented to the emergency service with the projectile located in the urethra, which was removed through the urinary meatus without complications. A review of the literature on migration of bullet projectiles was made.

Response of Novel Functionally-Graded Prepacked Aggregate Fibrous Concrete against Low Velocity Repeated Projectile Impacts.

Preplaced Aggregate Fibrous Concrete (PAFC) is a newly minted composite that has recently become more popular. The production of PAFC involves two essential processes; first, the fibres and coarse aggregate were filled into the empty framework to form the first layer of a natural skeleton, followed by grout injecting. A cement grout fills the voids in the first layer skeleton with slight compaction. This process is repeated to complete the remaining layers; hence, a type of Functionally-graded Preplaced Aggregate Fibrous Concrete (FPAFC) is obtained. The most recent studies revealed that the literature regarding the high-velocity projectile impact on fibrous concrete is well documented; however, the low-velocity repeated projectile impact on PAFC is still unexplored and needs particular emphasis. This research aims to investigate the FPAFC made with a new type of steel and polypropylene fibres against low-velocity projectile impact to fill this research gap. In the current study, twelve mixes were prepared with mono and hybrid combinations of fibres for pioneering the possible utilization of fibres in FPAFC. The maximum fibre dosage in this study is limited to 2.4%. The projectile impact resistance of FPAFC was assessed in line with penetration depth, front and rear damage surface area, weight loss, damage ratio and failure pattern. Additionally, a simplified analytical model was introduced to compute the ejected composite mass from the tested specimens. The results revealed that the addition of steel fibre in a single layer FPAFC exhibited an increasing compressive strength trend compared to the two/three-layered FPAFC. Furthermore, increasing the dosage of fibre at the bottom and top layers of FPAFC with a hybrid combination alleviates the spalling with an increasing number of impacts. The results from this research offer the reference information for more detailed research and studies of FPAFC under low-velocity projectile impact.

Temporal Bone Fractures Caused by Ballistic Projectiles: A Systematic Review.

OBJECTIVE: Ballistic injuries to the temporal bone are uncommon but devastating injuries that damage critical neurovascular structures. This review describes outcomes after ballistic injuries to the temporal bone and offers initiatives for standardized high-quality future research. DATA SOURCES: A systematic search of PubMed, Embase, and Cochrane. REVIEW METHODS: Studies in the review included adults who experienced temporal bone fractures due to gunshot wounds and survived longer than 48 hours. Individual case reports were excluded. The various searches returned 139 results, of which 6 met inclusion criteria. RESULTS: Most of the included studies are case series with low-level evidence that report a wide range of outcomes and follow-up. Outcomes include demographic patient information, audiologic outcomes, vascular injuries, intracranial complications, facial nerve function, and surgical indications. CONCLUSION: This review is the first to characterize the nature and progression of patients who experienced gunshot wounds to the temporal bone. Although all patients share an etiology of injury, they often have vastly different hospital courses and outcomes. This review provides a basis for future studies to guide care for these injuries, as most of the existing literature includes small dated case series.

Formation of oil-particle aggregates: Particle penetration and impact of particle properties and particle-to-oil concentration ratios.

Oil droplets in marine environment interact with particles to form oil particle aggregates (OPA), and alters the transport and fate of oil. We investigated the impact of particles properties on the formation of OPAs. It was found that the distribution of 9 µm spherical silica (sand) particles on the oil droplet was more uniform than the 3 µm silica particles, and it is likely due to the inertia of the larger particles causing them to lodge into the droplet. Also, the OPAs of the 3 µm silica particles were much smaller than those of the 9 µm particles. For kaolinite particles that are rod-like of length around 10 µm, it was found that increasing the hydrophobicity of the particles from a contact angle (CA) of ~ 29o to 38o, increases the penetration of the particles in the oil through a projectile penetration mechanism, whereby the particle possesses sufficient inertia to penetrate into the oil. However, a further increase in hydrophbocitiy (CA ~ 57o) caused the particles to agglomerate together and avoid the oil droplets. The oil droplets got smaller with time probably due to the penetration of the particles in them. For an oil concentration of 500 mg/L, a particle concentration of 100 mg/L was incapable of fragmenting the oil droplets, but particle concentration of 500 mg/L fragmented the droplets similarly to a concentration of 1500 mg/L. This is due to the larger coverage of the droplet surface area by the particles and the subsequent weakening of its structural rigidity through the reduction of the oil-water interfacial tension. The study shows that the fate (e.g., after 24 h) of OPAs greatly depends on the type of sediments where the oil spilled (sand versus clay) and their concentration.

Respiratory problems owing to severe metabolic alkalosis in infants presenting with hypertrophic pyloric stenosis.

OBJECTIVE: Uncorrected metabolic alkalosis in infantile hypertrophic pyloric stenosis (IHPS) could lead to perioperative apnea. However, the precise incidence of preoperative respiratory problems and the association with metabolic alkalosis are unknown. Therefore, we aimed to determine the incidence of preoperative respiratory problems in IHPS and to assess the association with metabolic alkalosis. METHODS: We retrospectively reviewed all patients diagnosed with IHPS during 2007-2017. Respiratory problems were classified as present or absent. With multivariate logistic regression we analyzed the association between bicarbonate and respiratory problems, corrected for gestational age and birth weight. RESULTS: We included 459 infants, of whom 23 developed preoperative respiratory problems (5.0%). Infants with preoperative respiratory problems were more often female (43.5% vs. 13.3% p = 0.001) and had significantly higher median serum levels of bicarbonate (32.0 mmol/L vs. 30.0 mmol/L), base excess (6.5 mmol/L vs. 5.3 mmol/L) and pCO2 (6.4 kPa vs. 5.9 kPa), compared to infants without respiratory problems. Multivariate analysis of serum bicarbonate and presence of respiratory problems showed an OR of 2.18 per 10 mmol/L (95% CI 1.21-4.71) (p = 0.009). The optimal bicarbonate cutoff point was 25.7 mmol/L (sensitivity 100%, specificity 13.4%). CONCLUSION: IHPS with metabolic alkalosis potentially results in preoperative respiratory problems. A lower bicarbonate target before surgery might be recommended and respiratory monitoring should be considered. LEVEL OF EVIDENCE: Level IV.

Propiedades balísticas de perdigones antidisturbios "menos letales" y su relación con trauma ocular severo en Chile / Ballistic properties of "less-lethal" shotgun pellets and severe ocular trauma in Chile

Se analiza el comportamiento balístico de dos tipos de perdigones "menos letales" usados por las fuerzas policiales en Chile para entender mejor los factores fundamentales que conllevan a la inusual cifra de lesiones oculares en el marco de las manifestaciones masivas ocurridas en Chile desde octubre de 2019. Para evaluar los riesgos de penetración y trauma ocular severo, se construyeron curvas de energía normalizada (E/a) en base a información publicada por las fuerzas policiales y fabricantes de municiones. Aun cuando el riesgo asociado al uso de las municiones según protocolos es leve, este artículo presenta que de todas formas existe riesgo de trauma ocular severo en todas las distancias de uso. La balística de los perdigones, combinada con la imprecisión de municiones multiproyec-tiles, son factores importantes para explicar la alta incidencia de trauma ocular severo. El caso de Chile es parte de un aumento global en la incidencia de lesiones oculares causadas por municiones consideradas menos letales, lo cual demanda una reevaluación de las políticas que regulan su uso.

The ballistic characteristics of two types of "less-lethal" multi-projectile shotgun rounds used by law enforcement in Chile are analyzed to better understand their contribution to the unusually high occurrence of ocular injuries at mass demonstrations since October 2019. Normalized energy (E/a) curves are constructed using publicly-available information from law enforcement and the manufacturers of the munitions to evaluate the risks of skin penetration and severe ocular trauma. Although the risk of penetration is small when these munitions are used according to local protocols, the risk of severe ocular trauma exists at all distances of approved use, and the ballistics of these pellets­along with the imprecision of multi-projectile shotgun rounds­help to explain the high inci-dence of severe ocular trauma. The example of Chile is part of a worldwide acceleration in the incidence of ocular injuries by "less-lethal" munitions and demands a reevaluation of their suitability for crowd control.

Prognosis of mortality and evolution in pancreatoduodenal trauma in patients with wound by projectile of firearm.

BACKGROUND: The wounds caused by the firearm projectile are published to date in a public health problem in the world. As an example, we mentioned the injuries caused by firearms are the first cause of death in the age group between 1 to 19 years in the United States, as in Mexico. OBJECTIVE: Analysis of the prognostic factors of mortality and evaluation of the evolution in patients with TPD due to abdominal HPPAF. METHOD: Retrospective, observational, descriptive study. Helped by 49 clinical files of patients who were admitted to the department of surgery of the University Hospital José Eleuterio González, between 2011 to 2015 and whose diagnosis was due to pancreatic trauma (TP), duodenal trauma (TD) or pancreatoduodenal trauma (TPD) by wounds caused by the firearm projectile. RESULTS: During a collection period of 5 years, a total of 49 clinical records applicable to the study were obtained according to the inclusion criteria, of which 36 (73%) suffered only from TD, 37 (75%) from TP and 24 (49%) about TPD. Significant differences were obtained for mortality associated with TD and TPD, but not for TP. The most affected organ as a lesion associated with a TPD was the liver, followed by thoracic structures and the stomach. The most significant risk factor for mortality was a prolonged stay in the intensive care unit. CONCLUSIONS: Data obtained are consistent with those consulted, providing new reproducible statistics for future studies regarding the increasing violence in our country and around the world.

ANTECEDENTES: Las heridas por proyectil de arma de fuego constituyen un problema de salud pública en el mundo. Como ejemplo mencionamos que este tipo de lesiones son la primera causa de muerte en el grupo de edad de 1 a 19 años en los EE.UU., al igual que en México. OBJETIVO: Análisis de los factores pronósticos de mortalidad y evaluación de la evolución en pacientes con TPD por HPPAF abdominal. MÉTODO: Estudio retrospectivo, observacional y descriptivo, realizado con 49 expedientes clínicos de pacientes que fueron admitidos en el departamento de cirugía del Hospital Universitario José Eleuterio González entre los años 2011 y 2015, cuyo diagnostico fue herida por proyectil de arma de fuego con trauma pancreático (TP), duodenal (TD) o pancreatoduodenal (TPD). RESULTADOS: Durante un periodo de recolección de 5 años se obtuvieron 49 expedientes clínicos aplicables al estudio según los criterios de inclusión, de los cuales 36 pacientes (73%) sufrieron únicamente TD, 37 (75%) TP y 24 (49%) TPD. Se obtuvieron diferencias significativas para la mortalidad asociada a TD y TPD, pero no para TP. El órgano más afectado como lesión asociada a un TPD fue el hígado, seguido de las estructuras torácicas y el estómago. El factor de riesgo para mortalidad más significativo fue una estancia prolongada en la unidad de cuidados intensivos. CONCLUSIONES: Los datos conseguidos concuerdan con los consultados, otorgando nueva estadística reproducible para futuros estudios respecto a la violencia creciente en nuestro país y alrededor del mundo.