Ball Size Research Articles

Effect of Ball Milling Treatment on Compositional Gradients in Functionally Graded Materials Fabricated by Centrifugal Slurry Methods

Ceramic-metal functionally graded materials (FGMs) are advantageous to two dissimilar materials joined directly together, which includes smoothing of thermal stress distributions, minimization or elimination of stress concentrations and singularities at the interface corners and increase in bonding strength. In this study, ZrO2/ 304 stainless steel (SUS304) FGMs with continuous gradient manners, not stepwise manners, were fabricated by a combination of centrifugal slurry methods and spark plasma sintering (SPS). The size and surface smoothness of the powders of SUS304 highly affected formation of compositional gradient patterns in the FGMs. Effects of ball milling time and ball sizes on such conditions of the powders as well as compositional gradients in the FGMs were investigated by microstructure observations with element analysis and hardness probing on the cross sections of the FGMs.

Hypo-eutectic microstructure formation and nanomechanical response in Sn-3.0Ag-0.5Cu solder balls: Effects of undercooling

The microstructure control and refinement in length scale are pursued in the development of next generations of Pb-free solder alloys with high reliability in harsh environments. In the present work, the influences of nucleation undercooling, as brought by solder ball size, over the microstructure evolution and nanomechanical behavior in Sn-3.0Ag-0.5Cu (wt%) Pb-free solder alloys, have been quantitively investigated using Differential Scanning Calorimeter (DSC), Scanning Electron Microscopy (SEM) and nanoindentation. The results reveal that undercooling increases with the decrease of solder ball size. The frequency of interlaced grain microstructure was significantly increased in 200 μm balls, with a further increase of undercooling by ~10 K. The volume fraction of primary β-Sn increased with larger undercooling, leading to microstructure refinement with a finer spacing of both β-Sn dendrite and eutectic Ag3Sn. The length scale of refinement is on the order of ~2, as the solder ball size reduced from 650 μm to 200 μm. Nano-hardness and creep resistance increase with smaller ball size and larger undercooling. Nano-hardness values are relatively higher as more eutectic regions being measured due to the strengthening effect of finer and denser eutectic Ag3Sn, and also the refinement of interlaced β-Sn grains. The creep exponent is insensitive to the loading force or solder ball size. The variation of nanomechanical deformation behavior was reduced in the 200 μm balls, due to the substantial microstructure refinement, while the dominant creep mechanism stays as the dislocation climb for various solder ball sizes.

Imaging and Pathologic Evaluation of Cryoablation of Woodchuck (Marmota Monax) Hepatocellular Carcinoma.

We characterized cryoablation as a mode of clinical intervention in adult woodchucks with hepatocellular carcinoma (HCC). Woodchucks (n = 4) were infected with woodchuck hepatitis virus at birth and developed LI-RADS-5 hypervascular HCC. At 21 mo of age, they underwent ultrasound (US), contrast-enhanced CT (CECT) imaging, and US-guided subtotal cryoablation (IcePearl 2.1 CX, Galil, BTG) of their largest tumor (Mean HCC volume of 49 ± 9 cm³). Cryoablation was performed using two 10-min freeze cycles, each followed by an 8-min thaw cycle. The first woodchuck developed significant hemorrhage after the procedure and was euthanized. In the other 3 woodchucks, the probe track was cauterized and all 3 completed the study. Fourteen days after ablation, CECT was performed, and woodchucks were euthanized. Explanted tumors were sectioned using subject-specific, 3D-printed cutting molds. Initial tumor volume, the size of the cryoablation ice ball, gross pathology and hematoxylin and eosin-stained tissue sections were evaluated. On US, the edges of the solid ice balls were echogenic with dense acoustic shadowing and average dimensions of 3.1 ± 0.5 × 2.1 ± 0.4 cm and cross-sectional area of 4.7 ± 1.0 cm ². On day 14 after cryoablation, CECT of the 3 woodchucks showed devascularized hypo-attenuating cryolesions with dimensions of 2.8 ± 0.3 × 2.6 ± 0.4 × 2.93 ± 0.7 cm and a cross-sectional area of 5.8 ± 1.2 cm². Histopathologic evaluation showed hemorrhagic necrosis with a central amorphous region of coagulative necrosis surrounded by a rim of karyorrhectic debris. A rim of approximately 2.5 mm of coagulative necrosis and fibrous connective tissue clearly demarcated the cryolesion from adjacent HCC. Partial cryoablation of tumors produced coagulative necrosis with well-defined ablation margins at 14 d. Cauterization appeared to prevent hemorrhage after cryoablation of hypervascular tumors. Our findings indicate that woodchucks with HCC may provide a predictive preclinical model for investigating ablative modalities and developing new combination therapies.

MP14-01 EVALUATION OF A NOVEL CYSTOSCOPIC CRYOCATHETER FOR THE IN SITU DESTRUCTION OF BLADDER CANCER

You have accessJournal of UrologyCME1 Apr 2023MP14-01 EVALUATION OF A NOVEL CYSTOSCOPIC CRYOCATHETER FOR THE IN SITU DESTRUCTION OF BLADDER CANCER Anthony Corcoran, Aaron Katz, Anthony Robilotto, Kristi Snyder, Kimberly Santucci, Robert VanBuskirk, John G. Baust, and John Baust Anthony CorcoranAnthony Corcoran More articles by this author , Aaron KatzAaron Katz More articles by this author , Anthony RobilottoAnthony Robilotto More articles by this author , Kristi SnyderKristi Snyder More articles by this author , Kimberly SantucciKimberly Santucci More articles by this author , Robert VanBuskirkRobert VanBuskirk More articles by this author , John G. BaustJohn G. Baust More articles by this author , and John BaustJohn Baust More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003234.01AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: There is a pressing need for the development of new devices facilitating advanced minimally invasive approaches for the in situ treatment of bladder cancer (BC). To this end, a new cystoscopic compatible cryocatheter (UroAblate) has been developed. When paired with the novel Pressurized Subcooled Nitrogen (PSN) cryoconsole, the cryocatheter delivers ultracold ablative temperatures to a targeted tissue in a closed loop manner. In this study, we evaluated cryocatheter performance for its potential use for cystoscopic in situ ablation BC. METHODS: A ∼1 m cryocatheter with a distal 1.5 cm ablation tip (connected to PSN) was passed through the working channel of a Ambu cystoscope. A laparoscopic approach was also utilized to visualize the transmural extension of the ice propagation. Evaluations included a 37°C ultrasound gel model, tissue engineered BC model and a chronic porcine study (4 animals, 7 day survival) wherein 10 lesions/animal were created throughout the bladder (bladder wall, trigone region, UO and distal ureter). Performance assessment included ice ball size, isotherm profile and destruction area. Single and double 0.5, 1, 1.5 and 2 min freeze protocols were evaluated. RESULTS: Bench studies demonstrated the generation of a 1.6cm iceball and the penetration of the -20°C isotherm to 0.87 cm following 2 mins. Analysis of tissue destruction using a BC tumor model revealed the creation of a 350 mm3 and 448 mm3 ablated volume following a single or double 2 min freeze, respectively. Porcine studies demonstrated the consistent generation of transmural lesions following freezing (single or double) for ≥1.5 min regardless of tissue thickness (range: 0.4 cm to 1.2 cm). All animals were found to have good overall health (maintained weight, appetite, mobility, energy levels, etc.) through the recovery period. No significant deviations were noted in CBC and serum chemistry bloodwork with the exception of elevated Creatine Kinase levels. Importantly, no fistulas or bowel/bladder perforations were noted in any animals. CONCLUSIONS: This study demonstrated that the cryocatheter was able to rapidly and effectively freeze targeted tissue via a cystoscopic approach. The results showed the device was able to consistently ablate a >1 cm area using a single 2 minute freeze protocol across all models. Analysis of the ablation efficacy revealed ∼80% destruction within the overall frozen mass. Although further testing and refinement are needed, these studies demonstrated the potential of this new approach to provide a next-generation strategy for the treatment of BC. Source of Funding: National Institutes of Health National Cancer Institute Grant No. 1R43CA210761-01A1 awarded to CPSI Biotech © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e182 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Anthony Corcoran More articles by this author Aaron Katz More articles by this author Anthony Robilotto More articles by this author Kristi Snyder More articles by this author Kimberly Santucci More articles by this author Robert VanBuskirk More articles by this author John G. Baust More articles by this author John Baust More articles by this author Expand All Advertisement PDF downloadLoading ...

Effect of Ball Size on Performance of Particle Damper

Abstract: The study of particle damping involves the understanding of the various forces and mechanisms that cause energy to be lost from vibrating systems, leading to the reduction of their amplitudes over time. The cantilever beam is used for experimentation. FFT analyzer is used to find the response parameters. The readings are taken with varying cavity dimensions, size of ball, packing ratio and ball material. The response parameters in the form of acceleration are noted by varying one experimental parameter. From the experimentation it is found that 5 mm ball with sand material is effective for the applied experimental set-up.

Relative Effects of Various Factors on Ice Ball Formation and Ablation Zone Size During Ultrasound-Guided Percutaneous Cryoneurolysis: A Laboratory Investigation to Inform Clinical Practice and Future Research.

Ultrasound-guided percutaneous cryoneurolysis provides analgesia using cold temperatures to reversibly ablate peripheral nerves. Cryoneurolysis probes pass a gas through a small internal annulus, rapidly lowering the pressure and temperature, forming an ice ball to envelope the target nerve. Analgesia is compromised if a nerve is inadequately frozen, and laboratory studies suggest that pain may be paradoxically induced with a magnitude and duration in proportion with the incomplete ablation. We therefore investigated the relative effects of various factors that may contribute to the size of the ice ball and the effective cryoneurolysis zone. A cryoprobe was inserted into a piece of meat, a gas was passed through for 2min, and the resulting ice ball width (cross-section) and length (axis parallel to the probe) were measured using ultrasound, with the temperature evaluated in nine concentric locations concurrently. The factor with the greatest influence on ice ball size was probe gauge: in all probe types, a change from 18 to 14 increased ice ball width, length, and volume by up to 70%, 113%, and 512% respectively, with minimum internal temperature decreasing as much as from -5 to -32°C. In contrast, alternating the type of meat (chicken, beef, pork) and the shape of the probe tip (straight, coudé) affected ice ball dimensions to a negligible degree. The ice ball dimensions and the zone of adequate temperature drop were not always correlated, and, even within a visualized ice ball, the temperature was often inadequate to induce Wallerian degeneration. Percutaneous probe design can significantly influence the effective cryoneurolysis zone; visualizing a nerve fully encompassed in an ice ball does not guarantee adequate treatment to induce the desired Wallerian degeneration because ice forms at temperatures between 0 and -20°C, whereas only temperatures below -20°C induce Wallerian degeneration. The correlation between temperatures in isolated pieces of meat and perfused human tissue remains unknown, and further research to evaluate these findings in situ appears highly warranted.

Intelligent defect inspection of flip chip based on vibration signals and improved gcForest

The defect inspection of flip chips has become a meaningful and challenging task with the decrease of size and distance of solder balls. In this paper, we proposed a novel defect diagnostic method for flip chips based on vibration signals and improved multi-grained cascade forest (gcForest). Firstly, the flip chip is excited by an air-coupled capacitive ultrasonic transducer, and the corresponding vibration signals of flip chip are captured by a laser scanning vibrometer. Then, the feature information of original vibration signals is extracted by muti-grained scanning (MGS) automatically. Finally, the extracted feature information is input into the cascaded forest for defect diagnosis. Considering the low data transmission efficiency and feature redundancy between MGS and cascaded forest, a feature extraction channel strategy based on kernel principal component analysis (KPCA) is introduced into the cascaded forest. Besides, in order to improve the generalization ability of the improved gcForest, the classifiers of each layer in cascade forest are upgraded. The results demonstrate the superiority of the improved gcForest over the traditional methods on experimental vibration data of flip chips, especially under small training sizes, which is very beneficial to practical engineering.

Measurement Analysis of Ice Ball Size during CT-Guided Cryoablation Procedures for Better Prediction of Final Ice Ball Size and Avoidance of Complications.

Introduction Cryoablation is the destruction of living tissue by the application of extreme freezing temperature. There has been an increase in the use of cryoablation in the management of musculoskeletal lesions, in particular fibromatosis. Aim This study aimed to measure the average and relative increase in size of the cryoablation ice ball after the first (10 minutes) and second freeze cycles (20 minutes) to accurately predict the size of the ice ball between first and second freezes to help prevent any unwanted damage of the nearby skin and neurovascular structures. This is especially important when ablating in relatively small body parts such as in the appendicular skeleton. Material and Methods Eight patients treated with cryoablation over a 12-month period for fibromatosis were, included in the study. The size and volume of the ice ball were measured during the first and second cycle of cryoablation. Results The average patient age of the cohort was 35.6 years old (min 28 and max 43). There was female predominance in the study (3:2, F:M). There was a significant increase (26%) in the linear dimensions and almost doubling in the volume of the ice ball between freeze cycles ( p -value = 0.0037 for dimensions and p -value = 0.0002 for volumes). Conclusion This pilot study is a preliminary attempt to predict the eventual size of the ice ball during cryoablation procedures when treating cases of fibromatosis. This should help in planning cryoablation to ensure decrease morbidity by preventing injury to adjacent critical structures (neurovascular bundle and skin).

Abstract P4-07-48: Preliminary results of the FIRST (FreezIng bReaST cancer in Brazil) trial: a before-after study

Abstract Background: Image-guided tumor ablation is a non-surgical minimally invasive therapy available for the local treatment of carcinomas as an alternative to surgical treatment. However, studies evaluating this therapy in early breast cancer present variable success rates, raising the question of whether omitting surgery is permissible. Ongoing studies such as the Frost and Ice3 Trial may change the context of cryoablation in the treatment of early breast cancer. Objective: The main objective of this study is to assess the effectiveness of cryoablation in the local treatment of early breast cancer. The secondary objectives are to analyze the negative predictive value of magnetic resonance imaging (MRI) in predicting response to therapy and to assess ice ball size in relation to the largest tumor size. Methods: Non-randomized, single-arm, multicenter clinical study conducted in Brazil. The inclusion criteria will be patients with unifocal invasive breast carcinoma, tumors smaller than or equal to 2.5 cm, lesion visualized on ultrasound, and surgery indicated as the first treatment option. The exclusion criteria will be in situ ductal carcinoma, multifocal or multicentric tumors, clinical axillary involvement, lesion-to-skin distance of less than 5 mm, presence of distant metastasis, and neoadjuvant treatment. All patients will undergo local cryoablation treatment, which will be followed by conventional surgical treatment after an interval of 14 to 28 days. Imaging tests (mammography, ultrasound, and breast MRI) will be performed before and after cryoablation. Cryoablation effectiveness will be assessed through its success rate, defined as the absence of invasive or in situ malignant neoplastic cells in the surgical specimen. If the expected cryoablation success rate corroborates the 92% rate presented in the ACOSOG Z1072 study for patients without multifocal disease, this study will need at least 32 patients to verify if the technique is satisfactory (success rate > 70%) considering power of 95% and an alpha of 5%. The study was approved by the local ethics committee and registered in the Clinical Trials. Recruiting has started in 2020 and is expected to end in 2024. Results: Until now, eight patients have been included, all of them with invasive breast carcinoma of no special type, RH positive and HER 2 negative, histological grade 1 or 2. The mean age of the patients is 57 years, and the mean tumor size is 1.1 cm (0.5–1.8 cm). All patients underwent two cycles of 6-minute freezing and 4-minute thawing with only one cryoprobe coupled to the Argon and Helium gas system. The complete ablation rate was 87.5% (7 of 8 cases) and the ablation rate considering only absence of invasive lesion was 100%. In our study, only one patient had in situ focal ductal carcinoma in one margin. The mean ice ball size on ultrasound was 3.8 x the size of the breast lesion. The negative predictive value of breast MRI was 100%. Conclusions Cryoablation is a promising therapy and may be an alternative to surgical treatment in patients with early breast cancer. This study confirms that this ablative technique is feasible. However, the results of other ongoing studies need to confirm the role of cryoablation in breast cancer treatment. ClinicalTrials.gov Identifier: NCT05398497 Citation Format: Vanessa M. Sanvido, Silvio E. Bromberg, Antonio R. Junior, Bruna Mayumi T. Tachibana, Afonso Nazário. Preliminary results of the FIRST (FreezIng bReaST cancer in Brazil) trial: a before-after study [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P4-07-48.

A unique soft tissue injury with devastating delayed consequences: A video case report.

A 52-year-old male presented to the emergency department (ED) after a fall down 5 stairs resulting in a loss of consciousness. On physical examination, a 4-cm hematoma was identified on the right lateral flank that emergency medical services personnel stated was the size of a golf ball on initial evaluation and appeared to expand over the course of his ED stay. Initial computed tomography (CT) (Figure 1) showed the hematoma; however, a bedside ultrasound (Video 1) and subsequent CT (Figure 2) were performed, demonstrating expansion of the hematoma with active extravasation. The qualities of this hematoma are suspicious for an uncommon condition called a Morel-Lavallée lesion (MLL), a closed degloving injury in which the subcutaneous tissues and fascia are separated by a hematoma that forms most frequently because of shearing forces.1, 2 Previous reports have documented MLLs secondary to motor vehicle collisions1 or biking accidents3 and some in conjunction with traumatic ventral wall hernias.2, 4 Diagnosis of this condition can occur through the use of ultrasound or magnetic resonance imaging, demonstrating a heterogenous fluid collection between the subcutaneous tissue and fascia.3 Although early detection of this condition is critical as the patient may continue to hemorrhage during evaluation, sequelae of this condition can be lifethreatening for a patient. Documented sequelae of MLLs range from infection of the lesion and neurovascular compromise to capsulation and scar tissue formation.3 A high index of suspicion for these lesions in patients with acute or remote trauma is critical as complications can occur up to a year later.3

Mechanochemical Synthesis of Shape-Anisotropic Particles through Wet Milling Using High-Energy Mills

A high-energy ball mill, such as a planetary ball mill, is widely used for preparing a homogeneously mixed powder and reducing particle size. Because of the high impact energy generated by the collision of ball media, the planetary ball milling is expected to produce local high-temperature and high-pressure zones. In wet milling, the solubility of the material varies owing to the local and instantaneous changes caused by the collision. Consequently, mechanochemical reactions through a dissolution–precipitation mechanism can be attained without external heating. In this paper, we show the wet mechanochemical process in water to synthesize functional hydrous or hydrate materials with various shapes, including nanosheets, nanotubes, plates, flakes, rods, and nanoparticles. Morphology-controlled particles can be obtained by only adjusting the milling conditions, such as milling time, ball size, and centrifugal acceleration. Further, the products can be converted into electrode materials for Li-ion batteries, retaining the precursor morphologies. This wet mechanochemical synthesis can be also applied in a bead mill, where mass production and continuous processing are possible. The wet mechanochemical process is a new particle synthesis method that can achieve both grinding and crystal growth.

Optimization of apigenin nanoparticles prepared by planetary ball milling: In vitro and in vivo studies

Abstract This study intended to optimize apigenin (APG) nanoparticle formulation prepared by planetary ball milling to enhance its dissolution rate and bioavailability using a design of experiment (DoE). In this study, polyvinyl pyrrolidone (PVP K30) was used as a nanoparticle stabilizer. The independent parameters of milling speed, milling ball size, and drug to solvent ratio were evaluated for their impacts on APG nanoparticles concerning the nanoparticle size (Y1), zeta potential (Y2), and drug dissolution efficiency after 60 min, notated as % DE60 (Y3). The milling ball size showed a significant antagonistic effect (P = 0.0210) on the size of APG nanoparticles, while milling speed had an agonistic effect on the zeta potential values of drug nanoparticles, ranging from low to medium speed levels. In addition, ANOVA analysis indicated that the effect of the drug-to-solvent ratio on the % DE60 of APG from the nanoparticle formulations was antagonistically significant (P = 0.015), and the quadratic effect of milling speed (AA) also had a significant antagonistic effect (P = 0.025) on the % DE60. Risk assessment analytical tools revealed that milling ball size and milling speed significantly affect the nanoparticle size. The drug/solvent ratio exerted a strong impact on % DE60. Furthermore, the maximum plasma concentration (C max) of the optimized APG nanoparticle formula increased by four folds. In addition, AUC0–t (ng·mL−1·h−1) for APG nanoparticle (353.7 ± 185.3 ng·mL−1·h−1) was higher than that noticed in the case of the untreated drug (149 ± 137.5 ng·mL−1·h−1) by more than two folds.

Nutrition Recommendations for Table Tennis Players-A Narrative Review.

Table tennis (TT) is the second most popular racket sport globally and was the sixth most widely played Olympic sport in 2005. It is an indoor racket sport requiring a mixture of power, agility, alertness and fast reactions. Players need to move quickly around a table to receive the ball and produce powerful returns. New rules such as increased ball size and a change in ball material have changed the ball's trajectory, increasing the overall duration and intensity of game play. Scientific research on TT is growing but there has been no systematic review of nutrition for the sport. This review provides nutritional recommendations for TT athletes based on the physiological demands of TT, including energy expenditure during training and competitions, and the main metabolic pathways of TT. Guidelines on the daily intakes of carbohydrate, protein and fat are discussed in addition to hydration strategies. Micronutrients of concern for TT athletes include iron, magnesium and vitamin D and their recommended intakes are also provided. The timing and dose of ergogenic aids that may improve TT performance such as caffeine, creatine, lutein and zeaxanthin and beta-alanine are reviewed. Specific nutritional strategies for intakes leading up to competitions, post training and competition recovery and nutritional strategies for travel are also addressed.

Lower Baskets and Smaller Balls Influence Mini-Basketball Players’ Throwing Motions

Children have different anthropometrical size ratios in relation to ball and basket compared to adults, but usually compete on the same basket height and field. Therefore, they have to adapt their throwing technique, which might result in movement patterns unfavorable for long-term performance development. In this study, we analyze how children adapt their throwing techniques to different conditions. Seven basketball players (10.14 ± 1.12 years) completed a total of 60 throws, combining different ball sizes, basket heights, and distances. The throwing movements were captured by a 3D motion capture system. Accumulated distances between all time courses of angles, angular accelerations, and velocities served as similarity measures and were analyzed by cluster analysis, including purity measures. Considering all throws, a division into seven clusters separated each individual. For all subjects, distances accounted for the most changes in the throwing motion (purity 0.81–1). In the subclusters, the basket heights were not a decisive condition (purity 0.42–0.63). However, an increase in purity was found compared to the main clusters. Children seem to adapt their movement behavior primarily to throwing distances and subordinately to basket heights, which indicates that changing playing conditions (e.g., closer 3-point line, lower baskets) might be beneficial in mini-basketball.

The Rest Is History

The Rest Is History

A rare case of superficial temporal artery pseudoaneurysm in a patient with neurofibromatosis type 1

Pseudoaneurysm of the superficial temporal artery (STA) is a rare clinical entity that has been linked with traumatic causes. Neurofibromatosis type I (NF-1) is an autosomal dominant disorder with known but uncommon vascular abnormalities that comprise stenoses, occlusions, aneurysms, fistulas and arteriovenous malformations. We presented a 46-year-old man with clinical features of NF-1 (e.g., café au lait spots, skin neurofibromas) coming to hospital because of a progressively enlarging and painful right temporal mass of about ping-pong ball size. He remembered having slapping a mosquito with his hands at the same area four days ago. CT angiography suggested development of a pseudoaneurysm and emergency surgery was performed to dissect the mass. Histopathological examination revealed disruption of arterial wall structures, including interruption of elastic lamina, expansion of smooth muscle layer, focal thrombosis and positive CD31 and smooth muscle actin staining, consistent with diagnosis of pseudoaneurysm. This is the first report of a STA pseudoaneurysm in patient with NF-1. Deficiency of neurofibromin may impact the integrity of vascular wall structures and predispose it to the development of pseudoaneurysm in the event of minor trauma like current case. Reference 1. Saliba E, Goldberg LJ. Superficial temporal artery pseudoaneurysm: report of two cases and review. J Cutan Pathol 2022; 49: 482–486.

On the Similarity of Austin Model and Kotake–Kanda Model and Implications for Tumbling Ball Mill Scale-Up

The aim of this theoretical investigation is to seek any similarities between the Austin model and the Kotake–Kanda (KK) model for the specific breakage rate function in the population balance model (PBM) used for tumbling ball milling and assess feasibility of the KK model for scale-up. For both models, the limiting behavior for small particle size-to-ball size ratio and the extremum behavior for a given ball size are described by “power-law.” Motivated by this similarity, specific breakage rate data were generated using the Austin model parameters obtained from the lab-scale ball milling of coal and fitted by the KK model successfully. Then, using the Austin’s scale-up methodology, the specific breakage rate was scaled-up numerically for various mill diameter scale-up ratios and ball sizes of 30–49 mm and coal particle sizes of 0.0106–30 mm. PBM simulations suggest that the KK model predicts identical evolution of the particle size distribution to that by the Austin model prior to scale-up. Upon scale-up, the differences are relatively small. Hence, modification of the exponents in the Austin’s scale-up methodology is not warranted for scale-up with the KK model. Overall, this study has established the similarity of both models for simulation and scale-up.

Size reduction performance evaluation of HPGR/ball mill and HPGR/stirred mill for PGE bearing chromite ore

In the present study, size reduction experiments were performed on High-Pressure Grinding Rolls (HPGR), ball mill and stirred mill of PGE bearing chromite ore. The performance of HPGR was evaluated in two stages of size reduction to reduce energy consumption. In the first stage of HPGR, the effect of operating variables such as the gap between the rolls, roll speed, and specific pressing force on product size (P80) and energy consumption (ECS) was investigated. The process to get the smallest product size was optimized within the experimental range of investigation. The crushed product of HPGR was subjected to grinding in the second stage in a ball mill and stirred mill. The effect of mill speed, grinding time, and ball size on the performance of the ball mill was investigated and the product was further investigated in the second stage. A comparative analysis of the ball mill and stirred mill performance and energy consumption at different grinding time intervals was also performed. It was found that the ball mill consumed 54.67 kWh/t energy to reduce the F80 feed size of 722.2 µm to P80 product size of 275.4 µm while stirred mill consumed 32.45 kWh/t of energy to produce the product size of 235.6 µm. It also showed that stirred mill produced finer product than the ball mill at around 40% lesser consumption of energy. It can be concluded that the HPGR-Stirred mill combination was a more energy-efficient grinding circuit than the HPGR-Ball mill combination for PGE bearing chromite ore.

A Simple, Low-Cost, and Green Method for Preparing Strong, Tough, and Ductile Poly(lactic acid) Materials with Good Transparency and Heat Resistance

Notwithstanding that unprecedented progress has been achieved in strengthening and toughening PLA materials, it is still a challenge to find a facile and low-cost way to improve poly(lactic acid) (PLA) strength, toughness, and ductility while maintaining transparency and biodegradability. Herein, strong, tough, transparent, and highly heat-resistant PLA materials with a nacre-like lamellar structure were fabricated via a simple, low-cost and additive-free pressure-driven flow process. PLA powders with a size under 500 μm and heterogeneous size distribution obtained from ball milling and size sieving were used to yield a PLA material with a dense and ordered crystalline structure after pressure-driven flow treatment. The newly formed structured PLA material exhibited exceptional mechanical properties, with tensile strength, elongation at break, impact strength, and tensile toughness reaching 88.9 MPa, 102.5%, 45.1 KJ/m2, and 81.2 MJ/m3, respectively. The refined strength, toughness, and ductility were attributed to more particles undergoing uniform plastic deformation during the pressure-driven flow treatment. The interface between particles in the powder was much larger and more tortuous, and the particles were firmer. Additionally, the newly formed tightly stacked crystal structure consisting of densely and orderly arranged nanosized crystals played an important role in improving the mechanical properties of PLA. Moreover, the newly formed structured PLA materials exhibited enhanced heat resistance and retained good transparency, with a visible light transmission of over 80%. Overall, this work presents a simple and efficient method for fabricating high-performance PLA materials that are strong, tough, ductile, transparent, heat-resistant, and easily recyclable.

Milling of pharmaceutical powder carrier excipients: Application of central composite design

Pharmaceutical powder carriers are often used to prevent agglomeration of a micronized drug in the co-milling process. Twenty-four pharmaceutical excipients were subjected to preliminary mild milling conditions in this work. Ten of them showed acceptable milling properties with alginic acid, calcium alginate, microcrystalline cellulose (Avicel® 200), carrageenan, and hypromellose having the best particle size reduction without any aggregation while maintaining a narrow span. For the latter five substances, circumscribed central composite design (CCD) evaluating the effect of the factors milling speed and timeon the responses (particle size, particle size distribution) for three milling ball sizes was used to establish optimal milling conditions. For all ten possible factor combinations and each ball size, a quadratic response surface model was used to predict the response variable. For three substances out of five, the best results were achieved using 5-mm balls. Thermal characteristics showed the good stability of excipients under optimized milling conditions.