Establishing and characterizing a permanent magnet system for the prototype of NIS's Kibble balance

The Kibble balance experiment is used to redefine the kilogram as a unit of mass based on the Planck constant. To demonstrate and understand the basic principle of the Kibble balance, the National Institute of Standards (NIS)-Egypt has constructed a prototype Kibble balance that can measure gram-level masses with 0.01% relative uncertainty. Through the construction of this prototype, the challenges can be studied and addressed to overcome the weaknesses of NIS’s prototype. This study presents the design and construction of the prototype Kibble balance. It also focuses on the design and performance of the magnetic system, which is a crucial element of the Kibble balance. Analytical modeling and finite element analysis were used to evaluate and improve the magnet system. Several other aspects were also discussed, including the yoke’s material and enhancing the magnetic profile within the air gap of the magnet system. Over a vertical distance of 30 mm inside the air gap, the magnetic flux density was found to be 0.3 T, and the uniformity was found to be 8 x 10 -5

Pulsed Electric Fields (PEF) as pre-treatment for freeze-drying of plant tissues

[EN] The influence of pulsed electric fields (PEF) treatment on freeze-drying for potato and strawberry tissues was investigated. Samples were pre-treated by PEF ( 400 V cm-1) for different treatment times. Freeze-drying was carried out at -17°C and 18.4 Pa or 30 Pa for potato and strawberry tissues, respectively. The effects of PEF pre-treatment was compared with intact samples. The drying time was reduced by 35% for potato and 30% for strawberry. The sample rehydration capacity and the electrolytes released during the rehydration were higher for pre-treated samples. Strawberries texture was characterized by the hardness, the cohesiveness and the springiness.Al-Sayed, L.; Boy, V.; Madieta, E.; Mehinagic, E.; Lanoisellé, J. (2018). Pulsed Electric Fields (PEF) as pre-treatment for freeze-drying of plant tissues. En IDS 2018. 21st International Drying Symposium Proceedings. Editorial Universitat Politècnica de València. 1575-1582. https://doi.org/10.4995/IDS2018.2018.7484OCS1575158

Pulsed Electric Fields (PEF) as pre-treatment for freeze-drying of plant tissues

[EN] The influence of pulsed electric fields (PEF) treatment on freeze-drying for potato and strawberry tissues was investigated. Samples were pre-treated by PEF ( 400 V cm-1) for different treatment times. Freeze-drying was carried out at -17°C and 18.4 Pa or 30 Pa for potato and strawberry tissues, respectively. The effects of PEF pre-treatment was compared with intact samples. The drying time was reduced by 35% for potato and 30% for strawberry. The sample rehydration capacity and the electrolytes released during the rehydration were higher for pre-treated samples. Strawberries texture was characterized by the hardness, the cohesiveness and the springiness.Al-Sayed, L.; Boy, V.; Madieta, E.; Mehinagic, E.; Lanoisellé, J. (2018). Pulsed Electric Fields (PEF) as pre-treatment for freeze-drying of plant tissues. En IDS 2018. 21st International Drying Symposium Proceedings. Editorial Universitat Politècnica de València. 1575-1582. https://doi.org/10.4995/IDS2018.2018.7484OCS1575158

Difatty Acyl-Conjugated Linear and Cyclic Peptides for siRNA Delivery

A number of amphiphilic difatty acyl linear and cyclic R₅K₂ peptide conjugates were synthesized by solid-phase peptide methods to enhance the interaction with the hydrophobic cellular phospholipid bilayer and to improve siRNA delivery and silencing. Binding to siRNA molecules was significantly less for the cyclic peptide conjugates. A gradual decrease was observed in the particle size of the complexes with increasing peptide/siRNA ratio for most of the synthesized peptides, suggesting the complex formation. Most of the complexes showed a particle size of less than 200 nm, which is considered an appropriate size for in vitro siRNA delivery. A number of fatty acyl-conjugated peptides, such as LP-C16 and LP-C18, displayed near complete protection against serum degradation. Flow cytometry studies demonstrated significantly higher internalization of fluorescence-labeled siRNA (FAM-siRNA) in the presence of LP-C16, LP-C18, and CP-C16 with 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) addition. Confocal microscopy confirmed the cellular internalization of fluorescence-labeled siRNA in the presence of LP-C16 and LP-C18 with DOPE when compared with cells exposed to DOPE/FAM-siRNA. While C16- and C18-conjugated peptides (especially linear peptides) showed silencing against kinesin spindle protein (KSP) and janus kinase 2 (JAK2) proteins, the addition of DOPE enhanced the silencing efficiency significantly for all selected peptides, except for CP-C16. In conclusion, C16 and C18 difatty acyl peptide conjugates were found to enhance siRNA delivery and generate silencing of targeted proteins in the presence of DOPE. This study provides insights for the design and potential application of optimized difatty acyl peptide/lipid nanoparticles for effective siRNA delivery