Effect of zirconia content and particle size on the properties of 3D‐printed alumina based ceramic cores

2021 ◽  
Author(s):  
He Li ◽  
Yongsheng Liu ◽  
Wenbo Li ◽  
Yansong Liu ◽  
Qingfeng Zeng
Keyword(s):  
Particle Size ◽  
3D Printed ◽  
Zirconia Content

scholarly journals 3D Printing of Drug Nanocrystals for Film Formulations

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3941
Author(s):  
Giorgia Germini ◽  
Leena Peltonen
Keyword(s):  
Particle Size ◽  
3D Printing ◽  
Polymer Films ◽  
Film Studies ◽  
Polymer Concentration ◽  
Physicochemical Characterization ◽  
Methyl Cellulose ◽  
Polymeric Film ◽  
Content Uniformity ◽  
3D Printed

The aim of the study was to prepare indomethacin nanocrystal-loaded, 3D-printed, fast-dissolving oral polymeric film formulations. Nanocrystals were produced by the wet pearl milling technique, and 3D printing was performed by the semi-solid extrusion method. Hydroxypropyl methyl cellulose (HPMC) was the film-forming polymer, and glycerol the plasticizer. In-depth physicochemical characterization was made, including solid-state determination, particle size and size deviation analysis, film appearance evaluation, determination of weight variation, thickness, folding endurance, drug content uniformity, and disintegration time, and drug release testing. In drug nanocrystal studies, three different stabilizers were tested. Poloxamer F68 produced the smallest and most homogeneous particles, with particle size values of 230 nm and PI values below 0.20, and was selected as a stabilizer for the drug-loaded film studies. In printing studies, the polymer concentration was first optimized with drug-free formulations. The best mechanical film properties were achieved for the films with HPMC concentrations of 2.85% (w/w) and 3.5% (w/w), and these two HPMC levels were selected for further drug-loaded film studies. Besides, in the drug-loaded film printing studies, three different drug levels were tested. With the optimum concentration, films were flexible and homogeneous, disintegrated in 1 to 2.5 min, and released the drug in 2–3 min. Drug nanocrystals remained in the nano size range in the polymer films, particle sizes being in all film formulations from 300 to 500 nm. When the 3D-printed polymer films were compared to traditional film-casted polymer films, the physicochemical behavior and pharmaceutical performance of the films were very similar. As a conclusion, 3D printing of drug nanocrystals in oral polymeric film formulations is a very promising option for the production of immediate-release improved- solubility formulations.

scholarly journals Filtration efficiency of face masks and veils as protective measures during COVID-19 pandemic

2021 ◽  
Author(s):  
Khaled S. Al-Hadyan ◽  
◽  
Ghazi A. Alsbeih Alsbeih ◽  
Najla M. Al-Harbi ◽  
Sara S. Bin Judia ◽  
...  
Keyword(s):  
Particle Size ◽  
Control Measure ◽  
Filtration Efficiency ◽  
Experimental Conditions ◽  
Surgical Masks ◽  
Significant Difference ◽  
Comparable Performance ◽  
The Face ◽  
3D Printed ◽  
The Mean

Wearing face masks have been implemented as a public and personal health control measure against the spread of coronavirus disease (COVID-19). However, the protection level of nonmedical face masks, such as women face veils, is still uncertain. This study aimed to assess the filtration efficiency (FE; percentage of particles retained by a mask) of different types of medical masks (either as sealed or unsealed, single or doubled), non-medical masks (cloth masks) and face veils. FE of face masks was evaluated using an in-house 3D-printed air duct connected to the Aerotrak particle counter with a capability of counting particle sizes of 0.3, 0.5, 0.7, 1, 2 and 5 μm. A set of 10 earloop surgical masks,10 tie-on surgical masks, 3 triple-layers reusable cloth masks and 3 types (short, medium and long) of traditional face veils were included in the study. The unsealed surgical masks showed intermediate FE (36.54-80.58%), with no observed differences between tie-on and earloop or single and doubled masks. For each mask type, the mean FE values of sealed surgical masks (FE≥99.16%) was significantly higher (P<0.001) than the unsealed ones (FE≤80.58%). No significant difference was observed in the mean FE values between unsealed surgical masks and either cloth masks (FE=23.19-75.35%, P=0.26) or face veils (FE=19.10- 70.68%, P=0.14). However, a mockup experiment showed that wearing a surgical mask under the face veil significantly improve the FE (33.73-79.18%; P<0.001). We conclude that besides sealed surgical masks that ensure optimal filtration under the experimental conditions, the unsealed surgical and cloth masks and face veils showed comparable performance and acceptable protection at 5 μm particle size, which is the most relevant particle size associated with COVID-19 infectious droplets. Wearing a surgical mask under the face veil significantly improves the FE compared to wearing a face veil alone.

Poly(vinyl alcohol) 3D printed tablets: The effect of polymer particle size on drug loading and process efficiency

2019 ◽  
Vol 561 ◽  
pp. 1-8 ◽  
Author(s):  
Marilena Saviano ◽  
Rita Patrizia Aquino ◽  
Pasquale Del Gaudio ◽  
Francesca Sansone ◽  
Paola Russo
Keyword(s):  
Particle Size ◽  
Vinyl Alcohol ◽  
Drug Loading ◽  
Polymer Particle ◽  
Process Efficiency ◽  
Poly Vinyl Alcohol ◽  
3D Printed

scholarly journals COVID-19 in the Clinic: Human Testing of an Aerosol Containment Mask for Endoscopic Clinic Procedures

2021 ◽  
pp. 019459982110291
Author(s):  
Elisabeth H. Ference ◽  
Wihan Kim ◽  
John S. Oghalai ◽  
Clayton B. Walker ◽  
Jee-Hong Kim ◽  
...  
Keyword(s):  
Particle Size ◽  
Health Care Workers ◽  
Aerosol Particles ◽  
Random Fluctuation ◽  
Particle Sizes ◽  
Level Of Evidence ◽  
Normal Breathing ◽  
Care Workers ◽  
3D Printed ◽  
Particle Counts

Objective To create an aerosol containment mask (ACM) for common otolaryngologic endoscopic procedures that also provides nanoparticle-level protection to patients. Study Design Prospective feasibility study . Setting In-person testing with a novel ACM. Methods The mask was designed in Solidworks and 3D printed. Measurements were made on 10 healthy volunteers who wore the ACM while reading the Rainbow Passage repeatedly and performing a forced cough or sneeze at 5-second intervals over 1 minute with an endoscope in place. Results There was a large variation in the number of aerosol particles generated among the volunteers. Only the sneeze task showed a significant increase compared with normal breathing in the 0.3-µm particle size when compared with a 1-tailed t test ( P = .013). Both the 0.5-µm and 2.5-µm particle sizes showed significant increases for all tasks, while the 2 largest particle sizes, 5 and 10 µm, showed no significant increase (both P < .01). With the suction off, 3 of 30 events (2 sneeze events and 1 cough event) had increases in particle counts, both inside and outside the mask. With the suction on, 2 of 30 events had an increase in particle counts outside the mask without a corresponding increase in particle counts inside the mask. Therefore, these fluctuations in particle counts were determined to be due to random fluctuation in room particle levels. Conclusion ACM will accommodate rigid and flexible endoscopes plus instruments and may prevent the leakage of patient-generated aerosols, thus avoiding contamination of the room and protecting health care workers from airborne contagions. Level of evidence 2

scholarly journals Polyvinyl Alcohol-Based 3D Printed Tablets: Novel Insight into the Influence of Polymer Particle Size on Filament Preparation and Drug Release Performance

2021 ◽  
Vol 14 (5) ◽  
pp. 418
Author(s):  
Andrea Gabriela Crișan ◽  
Alina Porfire ◽  
Rita Ambrus ◽  
Gábor Katona ◽  
Lucia Maria Rus ◽  
...  
Keyword(s):  
Particle Size ◽  
Drug Release ◽  
Polyvinyl Alcohol ◽  
Fused Deposition Modeling ◽  
Dosage Forms ◽  
Solid Dosage Forms ◽  
Manufacturing Method ◽  
Solid Dosage ◽  
Fused Deposition ◽  
3D Printed

Three-dimensional printing (3DP) by fused deposition modeling (FDM) has gained momentum as a promising pharmaceutical manufacturing method due to encouraging forward-looking perspectives in personalized medicine preparation. The current challenges the technology has for applicability in the fabrication of solid dosage forms include the limited range of suitable pharmaceutical grade thermoplastic materials. Hence, it is important to investigate the implications of variable properties of the polymeric carrier on the preparation steps and the final output, as versatile products could be obtained by using the same material. In this study, we highlighted the influence of polyvinyl alcohol (PVA) particle size on the residence time of the mixtures in the extruder during the drug-loaded filament preparation step and the consequent impact on drug release from the 3D printed dosage form. We enhanced filament printability by exploiting the plasticizing potential of the active pharmaceutical ingredient (API) and we explored a channeled tablet model as a design strategy for dissolution facilitating purposes. Our findings disclosed a new perspective regarding material considerations for the preparation of PVA-based solid dosage forms by coupling hot melt extrusion (HME) and FDM-3DP.

scholarly journals Impact of Particle Size of Ceramic Granule Blends on Mechanical Strength and Porosity of 3D Printed Scaffolds

Materials ◽  
2015 ◽  
Vol 8 (8) ◽  
pp. 4720-4732 ◽  
Author(s):  
Sebastian Spath ◽  
Philipp Drescher ◽  
Hermann Seitz
Keyword(s):  
Particle Size ◽  
Mechanical Strength ◽  
3D Printed

Microstructural characterization of laser-melted/roller-quenched dicalcium silicate

1988 ◽  
Vol 46 ◽  
pp. 582-583
Author(s):  
C. J. Chan ◽  
K. R. Venkatachari ◽  
W. M. Kriven ◽  
J. F. Young
Keyword(s):  
Particle Size ◽  
Raw Materials ◽  
Shape Change ◽  
Microstructural Characterization ◽  
Particle Size Effect ◽  
Dicalcium Silicate ◽  
Laser Melting ◽  
Uniform Size ◽  
Cell Shape Change ◽  
Wide Range

Dicalcium silicate (Ca2SiO4) is a major component of Portland cement. It has also been investigated as a potential transformation toughener alternative to zirconia. It has five polymorphs: α, α'H, α'L, β and γ. Of interest is the β-to-γ transformation on cooling at about 490°C. This transformation, accompanied by a 12% volume increase and a 4.6° unit cell shape change, is analogous to the tetragonal-to-monoclinic transformation in zirconia. Due to the processing methods used, previous studies into the particle size effect were limited by a wide range of particle size distribution. In an attempt to obtain a more uniform size, a fast quench rate involving a laser-melting/roller-quenching technique was investigated.The laser-melting/roller-quenching experiment used precompacted bars of stoichiometric γ-Ca2SiO4 powder, which were synthesized from AR grade CaCO3 and SiO2xH2O. The raw materials were mixed by conventional ceramic processing techniques, and sintered at 1450°C. The dusted γ-Ca2SiO4 powder was uniaxially pressed into 0.4 cm x 0.4 cm x 4 cm bars under 34 MPa and cold isostatically pressed under 172 MPa. The γ-Ca2SiO4 bars were melted by a 10 KW-CO2 laser.

Analytical Electron Microscopy study of two vehicle-aged automotive exhaust catalysts having dissimilar activities

1989 ◽  
Vol 47 ◽  
pp. 272-273
Author(s):  
Sooho Kim ◽  
M. J. D’Aniello
Keyword(s):  
Electron Microscopy ◽  
Particle Size ◽  
Noble Metal ◽  
Catalyst Deactivation ◽  
Analytical Electron Microscopy ◽  
Microscopy Study ◽  
Metal Particles ◽  
Automotive Exhaust ◽  
Exhaust Catalysts ◽  
Analytical Electron

Automotive catalysts generally lose-agtivity during vehicle operation due to several well-known deactivation mechanisms. To gain a more fundamental understanding of catalyst deactivation, the microscopic details of fresh and vehicle-aged commercial pelleted automotive exhaust catalysts containing Pt, Pd and Rh were studied by employing Analytical Electron Microscopy (AEM). Two different vehicle-aged samples containing similar poison levels but having different catalytic activities (denoted better and poorer) were selected for this study.The general microstructure of the supports and the noble metal particles of the two catalysts looks similar; the noble metal particles were generally found to be spherical and often faceted. However, the average noble metal particle size on the poorer catalyst (21 nm) was larger than that on the better catalyst (16 nm). These sizes represent a significant increase over that found on the fresh catalyst (8 nm). The activity of these catalysts decreases as the observed particle size increases.

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