RESUMEN
Incorporating exactly one monomer at a defined position during a chain polymerization is exceptionally challenging due to the statistical nature of monomer addition. Herein, photoinduced electron/energy transfer (PET) enables the incorporation of exactly one vinyl ether into polyacrylates synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. Near-quantitative addition (>96%) of a single vinyl ether is achieved while retaining >99% of the thiocarbonylthio chain ends. Kinetic studies reveal that performing the reactions at 2 °C limits unwanted chain breaking events. Finally, the syntheses of diblock copolymers are reported where molecular weights and dispersities are well-controlled on either side of the vinyl ether. Overall, this report introduces an approach to access acrylic copolymers containing exactly one chemical handle at a defined position, enabling novel macromolecular architectures to probe structure-function properties, introduce sites for de/reconstruction, store information, etc.
RESUMEN
The COVID-19 pandemic led to a large global effort to sequence SARS-CoV-2 genomes from patient samples to track viral evolution and inform public health response. Millions of SARS-CoV-2 genome sequences have been deposited in global public repositories. The Canadian COVID-19 Genomics Network (CanCOGeN - VirusSeq), a consortium tasked with coordinating expanded sequencing of SARS-CoV-2 genomes across Canada early in the pandemic, created the Canadian VirusSeq Data Portal, with associated data pipelines and procedures, to support these efforts. The goal of VirusSeq was to allow open access to Canadian SARS-CoV-2 genomic sequences and enhanced, standardized contextual data that were unavailable in other repositories and that meet FAIR standards (Findable, Accessible, Interoperable and Reusable). In addition, the Portal data submission pipeline contains data quality checking procedures and appropriate acknowledgement of data generators that encourages collaboration. From inception to execution, the portal was developed with a conscientious focus on strong data governance principles and practices. Extensive efforts ensured a commitment to Canadian privacy laws, data security standards, and organizational processes. This Portal has been coupled with other resources like Viral AI and was further leveraged by the Coronavirus Variants Rapid Response Network (CoVaRR-Net) to produce a suite of continually updated analytical tools and notebooks. Here we highlight this Portal, including its contextual data not available elsewhere, and the 'Duotang', a web platform that presents key genomic epidemiology and modeling analyses on circulating and emerging SARS-CoV-2 variants in Canada. Duotang presents dynamic changes in variant composition of SARS-CoV-2 in Canada and by province, estimates variant growth, and displays complementary interactive visualizations, with a text overview of the current situation. The VirusSeq Data Portal and Duotang resources, alongside additional analyses and resources computed from the Portal (COVID-MVP, CoVizu), are all open-source and freely available. Together, they provide an updated picture of SARS-CoV-2 evolution to spur scientific discussions, inform public discourse, and support communication with and within public health authorities. They also serve as a framework for other jurisdictions interested in open, collaborative sequence data sharing and analyses.
RESUMEN
Two HPLC columns packed with superficially porous packing material (Kinetex™ 1.7 and 2.6 µm C18 particles) were evaluated in terms of their physical properties and performance characteristics. These columns were compared to a column packed with a sub-2 µm totally porous material and to a Halo(TM) column packed with 2.7 µm C18 superficially porous packing. The columns packed with superficially porous particles displayed a comparably narrower size distribution, which is narrower than the distribution of the totally porous sub-2 µm particles. Physical characteristics of the Kinetex™ particles were evaluated in terms of surface area, pore diameter, and specific pore volume. Total, external, internal, and shell porosities among the four different columns were evaluated and compared. The specific permeability for the Kinetex™ columns showed values close to those predicted by the Kozeny-Carman equation. All four columns were evaluated in terms of their chromatographic performance and compared using the Knox equation. The columns packed with the 2.6 and 2.7 µm superficially porous materials showed reduced plate heights below 2, whereas the sub-2 µm particles showed values of 2.2 and above.
RESUMEN
Previc (1990) postulated that most peri-personal space interactions occurred in the lower visual field (LVF), leading to an advantage when compared to the upper visual field (UVF). It is not clear if extensive practice can affect the difference between interactions in the LVF/UVF. We tested male and female basketball varsity athletes and non-athletes on a DynaVision D2 visuomotor reaction task. We recruited basketball players because in their training they spend significant amount of time processing UVF information. We found a LVF advantage in all participants, but this advantage was significantly reduced in the athletes. The results suggest that training can be a powerful modulator of visuomotor function.
RESUMEN
Carbon nanoparticles obtained from the flame of an oil lamp were examined by means of capillary electrophoresis. The influence of buffer composition on the separation of the mixture of negatively charged carbon nanoparticles was studied by varying buffer selection, pH, and concentration. The electrophoretic pattern was affected by both the co- and counter-ion in the buffer solution, influencing selectivity and peak shape. The capillary electrophoretic separations at different pH revealed species with large electrophoretic mobilities under a wide range of pH. The mobility of selected species in the mixture of nanoparticles showed a strong dependence upon the solution ionic strength. The mobility of these nanoparticles as a function of ionic strength was compared to classical electrokinetic theory, suggesting that under the experimental conditions utilized, the species are small, highly charged particles with appreciable zeta potentials, even at low pH.