Ball Size Research Articles

The Synthesis of Hydroxyapatite Powder Using Shaker Mill Technique

Hydroxyapatite is a material that has the same structure and composition as the main minerals of human teeth and bones. This study's purpose was hydroxyapatite synthesis and determining the effect of variations in the ball sizes, the ratio of a mass of precursors to balls size, milling time, and ball size ratio of crystals and particles, surface area and morphology of hydroxyapatite produced by the mechanochemical method. Two different ball sizes (3mm and 6mm) and three different powder to ball ratio of 1:1.44; 1:2.88; and 1:4.32 were milled for 6 hours. Furthermore, the ball size ratio between the small ball (3 mm) and large ball (6 mm) was 1:1, 1:3, and 3:1 were milled for 2, 4, and 6 hours. The synthesized powder was analyzed by X-ray diffraction, Particle Size Analysis, Brunauer-Emmet-Teller analysis, and Scanning Electron Microscopy to confirm hydroxyapatite structure formation with nanocrystallite size and morphology in all variables. The crystallite size increased as the powder to ball ratio increased. The surface area at powder to ball ratio of 1:2.88 and ball size of 3 mm was 19.51 m2/g, while at ball size ratio of 1:1, it was 18.82 m2/g. The morphology of hydroxyapatite was uniform to granular with mol ratio Ca/P 1.81 for powder to ball ratio and ball size variation.

Mechanochemical process on layered compounds MoO3 and graphite to construct heterostructure composites with efficient lithium storage performance

This work successfully prepared homogeneous heterostructure nanocomposites comprised of few-layered MoO3 and graphite nanosheets (MoO3/C) on a large scale via a ball-milling method with bulk MoO3 and expandable graphite as raw materials. The shear and impact forces generated by the agate balls with a diameter of 2 mm can present the most ideal synergistic effect to strip the MoO3 nanosheets from its mother body with a small size and thickness. The obtained MoO3 nanosheets are distributed homogeneously on the surface of carbon nanosheets (<10 layers), providing many Li-storage sites and stable structure during the charging-discharging process. Hence, the obtained electrode material shows the high rate performance (817 mAh g−1@1000 mA g−1) and stable cycle performance (810 mAh g−1 after 70 cycles@200 mA g−1). More importantly, we basically understand the functional rule about the effects of the size of the agate balls on ball-milling efficiency for two kinds of layered materials.

Aggressiveness tumor: a case report of recurrent ameloblastoma in the mandible

Background: Ameloblastomas are rare odontogenic neoplasms of the mandible and maxilla. They have high recurrence rates if improperly treated. Due to their aggressive nature and high recurrence rate, treatment remains a matter of debate. Complete excision of the lesion with the least morbidity would be the therapeutic challenge.Case Report: A 67 years old woman complained of swelling on her left jaw four years ago, the jaw was small swelling initially, and then it has grown to the size of a tennis ball. She had a history of similar swelling on the same site 12 years back for which she was operated on (enucleation). On physical examination, there is a mass in the left mandibular bone above the surgical wound, hard, painless and motionless, with a size of 18 cm x 11 cm x 11 cm. Plain x-ray examination showed multiple cystic lesions in the left mandible. In this case, segmental mandibular resection was performed, followed by reconstruction using a K-wire.Discussion: Many treatment options range from conservative treatment of curettage, enucleation to radical surgical approaches of wide margin excision. Radical treatment approaches have the advantage of lowering the recurrence rates but at the same time pose extremely difficult challenges of reconstruction of the surgical defects.Conclusion: Ameloblastoma has high recurrence rate if it is not treated properly. At least 1 cm of healthy bone should be removed during surgical procedure beyond panoramic radiograph visible margins. In our patient, though radical surgery eliminated a large possibility of recurrence.

The effect of ball characteristics on head acceleration during purposeful heading in male and female youth football players

ABSTRACT Objective: The objective of this cross-sectional study was to explore the effects of different ball types and characteristics on head acceleration during purposeful heading in youth football players. Methods: Experienced male and female players (n = 61) aged between 12–17 years completed heading trials with 4 different balls (Ball 1 mass 192 grams (g), pressure 5.0 pounds per square inch (psi); Ball 2 432 g, 5.0 psi; Ball 3 255 g, 5.0 psi; Ball 4 430 g, 10.5 psi) whilst wearing a head-mounted accelerometer and gyroscope. Balls 1, 2 and 4 were size 5 balls; Ball 3 was a size 4 ball. Results: Multivariate analysis of variance and post-hoc univariate analyses revealed a statistically significant difference between ball type and head acceleration during heading for both linear acceleration (adjusted R2 = 0.68; F = 140.90; p = <0.001) and angular velocity (adjusted R2 = 0.28; F = 26.52; p = <0.001). Ball 1 (lightest size 5 ball) and Ball 3 (size 4 ball) demonstrated linear head accelerations up to 59% lower (p = <0.01) when compared with Ball 4 (size 5 regulated match ball). Discussion: Head acceleration during purposeful heading is influenced by changes to ball pressure, ball size and/or ball mass. Changing ball characteristics, particularly in youth football training when heading is being taught, should be an easy strategy to implement.

Noble-metal-free hydroxyapatite activated by facile mechanochemical treatment towards highly-efficient catalytic oxidation of volatile organic compound

Controlling of volatile organic compound (VOC) emitted from industrial processes as most abundant and harmful air pollutant, has become one of the most important global environmental issues due to the rapid urbanization and industrialization. As an alternative and new type catalyst instead of conventional noble-metal nanoparticles widely utilized in oxidative decomposition of VOC, here we report the superior catalytic performance with 100% CO2/CO conversion on hydroxyapatite (HAp, Ca10(PO4)6(OH)2) with structurally well-controlled active surface tailored via facile one-step mechanochemical treatment in ambient air. With detailed characterizations of particle morphology, crystallinity and chemical structure with respects to surface defect/oxygen vacancy formation, acidity/basicity and VOC affinity on HAps activated through different mechanical stresses when altered ball size is utilized in planetary ball-milling assisted mechanochemical process, it was found that the predominant defect/oxygen vacancy generation in PO43− site and enhanced basic site population established by selective mechanochemical activation of c-plane, facilitates the favorable catalytic oxidation route towards highly-efficient CO2/CO conversion of VOC. Regards to the cost-effectiveness and non-toxic nature of HAp, incorporated with the sustainable mechanochemical surface structure tuning process, the results presented in this work opens new strategy in development of novel noble-metal-free catalyst for VOC elimination and environmental cleaning techniques.

Two Consequences of Davies’ Hardy Inequality

Davies’ version of the Hardy inequality gives a lower bound for the Dirichlet integral of a function vanishing on the boundary of a domain in terms of the integral of the squared function with a weight containing the averaged distance to the boundary. This inequality is applied to easily derive two classical results of spectral theory, E. Lieb’s inequality for the first eigenvalue of the Dirichlet Laplacian and G. Rozenblum’s estimate for the spectral counting function of the Laplacian in an unbounded domain in terms of the number of disjoint balls of preset size whose intersection with the domain is large enough.

PENENTUAN NILAI SUSEPTIBILITAS DAN UKURAN PARTIKEL MAGNETIK PASIR ALAM LOGAS KABUPATEN KUANTAN SINGINGI MENGGUNAKAN VARIASI UKURAN BALL MILLING

Magnetic properties and morphology of natural sand has been carried out in Logas Village, Kuantan Singingi Regency have been determined. Iron sand samples were processed using iron sand separator (ISS) prior to ball milling for separating between magnetic and non magnetic particles. The product of ISS was milled for 90 hours using ball milling first step method with milling ball size of 1.5 cm. Themagnetic and non-magnetic particles of ball milling products were separated using Neodymium Iron Boron (NdFeB) magnet. The product of ball milling first step then was milled for another 30 hours with milling ball size of 0.5 cm and 0.7 cm. The susceptibility and mass susceptibility were determined based on magnetic induction of a selenoid measured using Probe Magnetic Pasco PS-2162. The composition of Logas natural sand was measured using x-ray fluorescence spectroscopy (XRF). The morphology of the magnetic particles are determined using scanning electron microscope (SEM). The results showed that the particle size of natural sand for 90 hours + 30 hours milling displays the particle sizes from 100 µm to 800 µm. As for the particle size of the samples synthesized with 90 hours + 30 hours for 0.7 cm milling ball size, the particles are almost evenly distributed, which is about 5 µm to 100 µm. The content of Fe and Ti in the sample has increased while for Si has decreased. Mass susceptibility increases with increasing ball milling time and ball milling size.

Gypsum-plasters mixed with polystyrene balls for building insulation: Experimental characterization and energy performance

In order to reduce the heat loss from envelopes and to ensure energy saving in building refurbishment, polystyrene balls are added to Moroccan natural gypsum plaster. A complete characterization of the mechanical, thermal, and acoustic properties of the samples is carried out, taking into account different contents and diameters of the polystyrene balls. Increasing balls size, flexural strength peak value occurred with a lower polystyrene percentage. Thermal properties were measured by means of Small Hot Box apparatus. The values of conductivity were 0.191 and 0.116 W/mK for 10% and 30% addition of the smallest polystyrene balls, respectively. The acoustic properties were measured by means of a Kundt’s Tube, in terms of absorption coefficient and sound insulation. The absorption coefficients were slightly higher than the ones of standard plasters. As concerning insulation properties, a worse performance was expected, due to the lower density of the samples with the balls, according to the Mass Low. Anyway the transmission loss values were up to 45 dB, with a reduction of only 2–3 dB with respect to the samples without balls, showing a good performance for the proposed composites. Finally, dynamic energy simulations for a case study showed that polystyrene plaster with smaller balls applied on the wall surfaces of a residential building involved benefits both for heating and cooling energy demand. A small thickness (3 cm) of insulating material could be a suitable solution in order to enhance the thermal and acoustic performance and to reduce environmental impact of the construction systems.

Rapunzel Sendromuna Bağlı İntestinal Obstrüksiyonun Farklı Bir Klinik Sunumu: İshal

Trichobezoars are defined as accumulation of hair or hair like substances in the stomach and/or small intestinal. It’s called Rapunzel syndrome when the accumulated hair ball pass the pylorus and reaches the small intestines and colon from the stomach. Clinical findings and treatment methods may vary according to the localization and size of the hair ball. In the literature; there are a limited of number publications about trichobezoar and Rapunzel syndrome but there hasn’t been a report of intestinal obstruction due to trichobezoar presenting to the emergency department with diarrhea. In this report; we will present a patient who applied to the emergency department with diarrhea and vomiting associated with intestinal obstruction due to Rapunzel syndrome.

Optimal Artificial Boundary Condition for Random Elliptic Media

We are given a uniformly elliptic coefficient field that we regard as a realization of a stationary and finite-range ensemble of coefficient fields. Given a right-hand side supported in a ball of size $$\ell \gg 1$$ and of vanishing average, we are interested in an algorithm to compute the solution near the origin, just using the knowledge of the given realization of the coefficient field in some large box of size $$L\gg \ell $$ . More precisely, we are interested in the most seamless artificial boundary condition on the boundary of the computational domain of size L. Motivated by the recently introduced multipole expansion in random media, we propose an algorithm. We rigorously establish an error estimate on the level of the gradient in terms of $$L\gg \ell \gg 1$$ , using recent results in quantitative stochastic homogenization. More precisely, our error estimate has an a priori and an a posteriori aspect: with a priori overwhelming probability, the prefactor can be bounded by a constant that is computable without much further effort, on the basis of the given realization in the box of size L. We also rigorously establish that the order of the error estimate in both L and $$\ell $$ is optimal, where in this paper we focus on the case of $$d=2$$ . This amounts to a lower bound on the variance of the quantity of interest when conditioned on the coefficients inside the computational domain, and relies on the deterministic insight that a sensitivity analysis with respect to a defect commutes with stochastic homogenization. Finally, we carry out numerical experiments that show that this optimal convergence rate already sets in at only moderately large L, and that more naive boundary conditions perform worse both in terms of rate and prefactor.

Influence of Drop Height on the Impact Characteristics of Futsal Ball Size Four

Futsal research on the ball characteristic has received little scientific attention. Recently modern football has been developed that afford excellent ball control and delivering. Difference constructions and sizes of ball deliver different characteristics of the ball. The purpose of this study is to examine Futsal ball size four deformations and coefficient of restitution (COR) during the impact. In this study, the Futsal ball was dropped vertically under three conditions. A subject performed five repetitive drops off the ball to impact a steel plate. The ball velocity was measured by SparkVue motion sensor attached on the top of the apparatus while the deformation was recorded using a high-speed video camera, that can up to 1,000 frames per second. From the experiment, the ball deformation and COR were measured. The results obtained showed the deformation and COR value vary with different heights for the same type of Futsal ball size four. It shows that the different heights of ball drops give different ball impact characteristics. It was found that the COR depended on the amount of the deformation of the ball.

Automatic detection of cotton balls during brain surgery: Where deep learning meets ultrasound imaging to tackle foreign objects.

Cotton balls are a versatile and efficient tool commonly used in neurosurgical procedures to absorb fluids and manipulate delicate tissues. However, the use of cotton balls is accompanied by the risk of accidental retention in the brain after surgery. Retained cotton balls can lead to dangerous immune responses and potential complications, such as adhesions and textilomas. In a previous study, we showed that ultrasound can be safely used to detect cotton balls in the operating area due to the distinct acoustic properties of cotton compared with the acoustic properties of surrounding tissue. In this study, we enhance the experimental setup using a 3D-printed custom depth box and a Butterfly IQ handheld ultrasound probe. Cotton balls were placed in variety of positions to evaluate size and depth detectability limits. Recorded images were then analyzed using a novel algorithm that implements recently released YOLOv4, a state-of-the-art, real-time object recognition system. As per the radiologists' opinion, the algorithm was able to detect the cotton ball correctly 61% of the time, at approximately 32 FPS. The algorithm could accurately detect cotton balls up to 5mm in diameter, which corresponds to the size of surgical balls used by neurosurgeons, making the algorithm a promising candidate for regular intraoperative use.

Correction to: “Ultrasonic nanocrystalline surface modification of low strength aluminum alloy: trade-off between surface integrity and production rate aiming at desired fatigue life”

In processing of metallic material by ultrasonic nanocrystalline surface modification (UNSM), obtaining high quality sample with desired surface property needs a careful control on processing factors. The condition would be more critical when the process is designed for match production. In such condition, both of surface integrity and production rate should be taken into account. To meet both of goals, in the present study, an experimental work was made to analyze how the UNSM process factors influences the surface integrity under desired values of production rate. In order to do so, series of experiments based on small fraction central composite design were carried out including static pressure, vibration amplitude, spindle speed, feed rate, and ball size as input parameters. Also, the surface roughness, compressive residual stress, and machining time were considered performance measures. A hybrid optimization approach including gray relational analysis and desirability function was proposed to obtain desired surface integrity under minimum value of machining time. Different criteria based on importance of production rate and surface integrity were separately defined and controlled by variation of weight factors. It is found that considering the production rate as dominant criterion leads to production of samples with maximum high cycle fatigue life. This is due to selection high spindle speed that enhances both production rate and surface quality. On the other hand, considering overall value of surface integrity as dominant criterion of optimization leads to producing sample with desired values of low cycle fatigue life. This effect can be attributed to selection of low spindle speed that deteriorates surface finish but enhances the compressive residual stress.

Different Gymnastic Balls Affect Postural Balance Rather Than Core-Muscle Activation: A Preliminary Study

Background: In proprioceptive training, unstable devices produce multidirectional perturbations that must be counterbalanced by the postural control systems and core-muscle activation. We investigated whether different sizes and shapes of three gymnastic balls could affect core-muscle activation and postural balance when performing the same exercise. Methods: Eleven young healthy subjects were assessed on the balls, assuming two body postures (bipedal seated and unipedal seated) and performing a dynamic exercise. Two balls were spherical with different diameters, and one was ovoid. Postural balance and muscle activation were assessed through center of pressure (CoP)-related parameters and surface electromyography. Results: Statistical analysis showed a significant effect of the gymnastic balls (p &lt; 0.001) and the body postures (p &lt; 0.001) for the CoP-related parameters, with the ovoid shape and the bipedal sitting representing the easiest conditions. Core-muscle activation was affected only by body postures, with a higher activation in the unipedal sitting (p &lt; 0.01). In the dynamic exercise, significant differences were only detected for the CoP-related parameters (p &lt; 0.001). Conclusions: The shapes and sizes of the gymnastic balls produced different degrees of destabilization under the same body posture but left the core-muscle activation unaltered. In the dynamic exercise, the conformation of the balls did not represent the main determinant in producing destabilizing effects.

The Motor Impact of the Static Balance in the Up Plank Position on Three Different Balls in Physical Activities of Physical Education Students.

The present study aimed to assess the capacity of stability and motor impact in the development of the balance of student athletes by reducing the support surface on the ball in the up plank position, by using three categories of balls of equal size, but with different elasticity and weight. In this study, the second aim was to investigate the differences in maintaining static balance, on different balls, between those who are practicing individual sports or team sports. The total study sample include 48 students, active athletes (45.8% of individual sports and 54.2% of team sports), age X ± SD 18.74 ± 1.94 years. The research included two test sessions (initial and final) applied in two stages. The static balance tests were performed by measuring the time maintaining the up plank position with two and three points of support on the three balls, with different characteristics of elasticity and ranges of deformation: medical ball, handball ball and fitness ball. The results of the study showed that the superior initial and final results were recorded on the fitness ball, and the inferior results on the medicine ball. The upper difference was recorded at the up plank position with two support points (arms, legs) on the fitness ball, at 4980 s, and the lowest in the same test on the medical ball, at 3420 s. The largest difference was recorded at the up plank position with three support points on the handball ball, at 7.082 s, and the lowest in the same test on the medical ball, at 3.093 s. The subjects of the study perceived that the most difficult position to execute was the up plank position on the medical ball with two support points, with 43.8%, and the easiest stability was registered in the up plank position on the fitness ball with three points of support, of 37.5%. The relevance of the research results from the possibility of using different balls in conditions of positioning and body posture with a diminished support base in order to improve physical fitness.

Ultrasonic nanocrystalline surface modification of low strength aluminum alloy: trade-off between surface integrity and production rate aiming at desired fatigue life

In processing of metallic material by ultrasonic nanocrystalline surface modification (UNSM), obtaining high quality sample with desired surface property needs a careful control on processing factors. The condition would be more critical when the process is designed for match production. In such condition, both of surface integrity and production rate should be taken into account. To meet both of goals, in the present study, an experimental work was made to analyze how the UNSM process factors influences the surface integrity under desired values of production rate. In order to do so, series of experiments based on small fraction central composite design were carried out including static pressure, vibration amplitude, spindle speed, feed rate, and ball size as input parameters. Also, the surface roughness, compressive residual stress, and machining time were considered performance measures. A hybrid optimization approach including gray relational analysis and desirability function was proposed to obtain desired surface integrity under minimum value of machining time. Different criteria based on importance of production rate and surface integrity were separately defined and controlled by variation of weight factors. It is found that considering the production rate as dominant criterion leads to production of samples with maximum high cycle fatigue life. This is due to selection high spindle speed that enhances both production rate and surface quality. On the other hand, considering overall value of surface integrity as dominant criterion of optimization leads to producing sample with desired values of low cycle fatigue life. This effect can be attributed to selection of low spindle speed that deteriorates surface finish but enhances the compressive residual stress.

Property of Sn-37Pb solder bumps with different diameter during thermal shock

PurposeThe impact strength of solder joint under high strain rate was evaluated by board level test method. However, the impact shear test of single solder bump was more convenient and economical than the board level test method. With the miniaturization of solder joints, solder joints were more prone to failure under thermal shock and more attention has been paid to the impact reliability of solder joint. But Pb-free solder joints may be paid too much attention and Sn-Pb solder joints may be ignored.Design/methodology/approachIn this study, thermal shock test between −55°C and 125°C was conducted on Sn-37Pb solder bumps in the BGA package to investigate microstructural evolution and growth mechanism of interfacial intermetallic compounds (IMCs) layer. The effects of thermal shock and ball diameter on the mechanical property and fracture behavior of Sn-37Pb solder bumps were discussed.FindingsWith the increase of ball size, the same change tendency of shear strength with thermal shock cycles. The shear strength of the solder bumps was the highest after reflow; with the increase of the number of thermal shocks, the shear strength of the solder bumps was decreased. But at the time of 2,000 cycles, the shear strength was increased to the initial strength. Minimum shear strength almost took place at 1,500 cycles in all solder bumps. The differences between maximum shear strength and minimum shear strength were 9.11 MPa and 16.83 MPa, 17.07 MPa and 15.59 MPa in φ0.3 mm and φ0.4 mm, φ0.5 mm and φ0.6 mm, respectively, differences were increased with increasing of ball size. With similar reflow profile, the thickness of IMC decreased as the diameter of the ball increased. The thickness of IMC was 2.42 µm and 2.17 µm, 1.63 µm and 1.77 µm with increasing of the ball size, respectively.Originality/valuePb-free solder was gradually used to replace traditional Sn-Pb solder and has been widely used in industry. Nevertheless, some products inevitably used a mixture of Sn-Pb and Pb-free solder to make the transition from Sn-Pb to Pb-free solder. Therefore, it was very important to understand the reliability of Sn-Pb solder joint and more further research works were also needed.

A Survey on Object Detection and Tracking in Soccer Videos

"The players and ball are the most important object in soccer game videos and detected them are a challenging task because of many difficulties, such as shadow and illumination, ball size, several other objects look like a ball, often the ball overlapping with players or merged with lines, as well as the ball may be disappear which be hidden in the stadium or flying on air, and similar appearance of players, etc. The detect ball is the first step for tracking in broadcast soccer video. There are several methods of ball-tracking are based on their problem. In this paper, we have discussed different methods of object detection and tracking in the soccer videos which are available in the literature.

Dependence of the dissipated energy of particles on the sizes and numbers of particles and balls in a planetary ball mill

The dissipated energy received by the particles during collisions in a high-energy ball-milling can vary due to the breakage and/or aggregation of the particles, that is, a change in the particle size. To investigate the energy variations, a numerical analysis of the behavior of particles and balls in a planetary ball mill was carried out under various conditions, considering different sizes and numbers of particles and balls using the discrete element method (DEM). The variable sizes and numbers of particles and balls affected the contact force, collision frequency, and types of particle collisions, resulting in variations in the dissipated energy distribution and specific dissipated power, even at a constant ball-to-particle filling mass ratio (BPR). The variation in specific dissipated power was expressed as a function of the sizes of the particles and balls and the BPR. According to the obtained empirical formula, the particle-to-ball size ratio strongly affects the specific dissipated power rather than the BPR. The results suggest that based on the energy variations with particle size and number, using balls of appropriate size and number can control the dissipated energy of particles, which may lead to the designing of energy-efficient milling processes.

Modelling of the High-Energy Ball Milling Process

In this paper, the milling parameters of high energy ball mill (Fritsch Pulverisette 7) like vial geometry, number and size of balls and speed of the mill were modelled and discussed. Simulations through discrete element method (DEM) provide correlation between the milling parameters. A mathematical model is used to improve and develop this process. The results show that the loss of powder mass can remarkably improve the performance of milling. The balls made of stainless-steel have a positive effect on the milling efficiency. The simulation shows that the high ball milling velocities can contribute to faster particle size reduction.