Influence of fused deposition modelling printing parameters on tablet disintegration times: a design of experiments study

Despite the importance of process parameters in the printing of solid dosage forms using fused deposition modelling (FDM) technology, the field is still poorly explored. A design of experiment study was conducted to understand the complete set of process parameters of a custom developed FDM 3D printer and their influence on tablet disintegration time. Nine settings in the Simplify 3D printing process design software were evaluated with further experimental investigation conducted on the influence of infill percentage, infill pattern, nozzle diameter, and layer height. The percentage of infill was identified as the most impactful parameter, as increasing it parabolically affected the increase of disintegration time. Furthermore, a larger nozzle diameter prolonged tablet disintegration, since thicker extruded strands are generated through wider nozzles during the printing process. Three infill patterns were selected for in-depth analysis, demonstrating the clear importance of the geometry of the internal structure to resist mechanical stress during the disintegration test. Lastly, layer height did not influence the disintegration time. A statistical model with accurate fit (R2 = 0.928) and predictability (Q2 = 0.847) was created. In addition, only the infill pattern and layer height influenced both the uniformity of mass and uniformity of the disintegration time, which demonstrates the robustness of the printing process

PROJEKTNI TJEDAN – ŽIVIMO ZDRAVO JER SE ZDRAVO HRANIMO I KREĆEMO

Kao učitelji imamo važnu ulogu u oblikovanju djetetovog odnosa prema zdravom načinu života.S tom svrhom smo se u prvom tjednu u lipnju više posvetili zdravlju u našoj školi. Imali smo različite aktivnosti. Pazili smo na zdravu prehranu, više smo se kretali (učenici su svaki dan trčali barem 7 minuta i vježbali jogu), pili dovoljne količine vode i posvetili sadržajima namijenjenima zdravlju. S učiteljicom engleskog jezika pripremili smo dva sata međupredmetnog povezivanja spajanjem odjela 1., 2. i 3. razreda koji su obuhvaćali aktivnosti s područja slovenskog i engleskog jezika, matematike, upoznavanja okoliša, sporta i glazbene umjetnosti

Residual stress in high velocity impact coatings modeling approach

High velocity impact coatings are produced by techniques such as cold spray, kinetic spray, warm spray, HVOF, supersonic plasma spraying, etc. All these processes have in common the impact of particles at high velocities that produce peening of the surface and induce compressive residual stresses in the in-plane orientation in the coating. If the process involves a significant heat input, quenching of splats and thermal mismatch between coating and substrate, it would add residual stress to the peening to define the final stress state. Physical variables, including: particle temperature and velocity, particle mass, particle morphology, and local deposition temperature are studied to observe their effect on residual stresses, and define their possible manipulation to design coatings of desired average residual stress. For instance, to increase the peening effect, particles can be projected faster while keeping the local deposition temperature low. Modeling the impact of particles allows to resolve for key parameter selection via a sensitivity analysis. A contour map is produced for parameter selection based on the modeling of particle impact (via a FEA Explicit Model) and the subsequent layer-by-layer coating formation (via a FEA Implicit Model) employing ABAQUS code. The Johnson-Cook model for high strain, strain rate and temperature is used as the constitutive equation for the study of impact and rapid cooling.Los recubrimientos de alta velocidad de impacto son producidos mediante técnicas tales como rociado en frío, rociado cinético, rociado caliente, HVOF, rociado de plasma supersónico, etc. Todos estos procesos tienen en común el impacto de partículas a altas velocidades que produce peening en la superficie e induce esfuerzo residual compresivo en dirección planar hacia el recubrimiento. Si el proceso involucra un ingreso de calor significativo, enfriamiento súbito de splats y descompensación térmica entre recubrimiento y sustrato, un esfuerzo residual térmico es sumado al esfuerzo provocado por el peening para definir el estado de esfuerzo final del sistema. En el presente trabajo se estudia variables físicas como velocidad y temperatura de partícula, masa de partícula, morfología de partícula, masa de partícula y temperatura local de deposición del sustrato con el fin de observar su efecto sobre el esfuerzo residual, y definir su posible manipulación para el diseño de recubrimientos con esfuerzo residual promedio adecuado. Por ejemplo, para aumentar el efecto de peening, las partículas pueden ser proyectadas a mayor velocidad mientras se mantiene la temperatura local de deposición del sustrato baja. Modelar el impacto y enfriamiento de partículas durante la deposición del recubrimiento permite realizar una selección de parámetros clave a través de un análisis de sensibilidad. Un mapa de contorno es producido para selección de parámetros en base a simulación de impacto de partícula (empleando FEA Explicit) y la subsecuente simulación de formación de recubrimiento capa-por-capa (empleando FEA Implicit) mediante el código ABAQUS. El modelo Johnson-Cook para alta deformación, tasa de deformación y temperatura es usado como la ecuación constitutiva para el estudio del impacto y rápido enfriamiento de partículas en este modelo

Two Nomogram Examples for Predicting the Likelihood of Nonsentinel Lymph Nodes Metastases in Early Breast Cancer Patients

Nomograms are useful tools in clinical medicine. In the article, two nomograms for predicting the likelihood of nonsentinel lymph node metastases in early breast cancer patients are presented. The first one was created in the Memorial Sloan Kettering Cancer Center. We validated this nomogram in the patients grouped by the preoperative ultrasound examination of the axilla and found important differences between the groups. The second nomogram created at the Institute of Oncology Ljubljana includes also the information on the preoperative US examination of the axilla, which is a strong independent variable. We found this nomogram performing better in our population of patients