Analysing sentiment change detection of Covid-19 tweets.

The Covid-19 pandemic made a significant impact on society, including the widespread implementation of lockdowns to prevent the spread of the virus. This measure led to a decrease in face-to-face social interactions and, as an equivalent, an increase in the use of social media platforms, such as Twitter. As part of Industry 4.

Preparation of individual magnetic sub-levels of He(2S) in a supersonic beam using laser optical pumping and magnetic hexapole focusing.

We compare two different experimental techniques for the magnetic-sub-level preparation of metastable He in the 2S level in a supersonic beam, namely, magnetic hexapole focusing and optical pumping by laser radiation. At a beam velocity of v = 830 m/s, we deduce from a comparison with a particle trajectory simulation that up to 99% of the metastable atoms are in the M = +1 sub-level after magnetic hexapole focusing. Using laser optical pumping via the 2P-2S transition, we achieve a maximum efficiency of 94% ± 3% for the population of the M = +1 sub-level.

Separation of reaction product and palladium catalyst after a Heck coupling reaction by means of organic solvent nanofiltration.

Organic solvent nanofiltration (OSN) is a recently commercialized technology, which we have used to develop a method for the separation of a target product and the Pd catalyst from a Heck coupling postreaction mixture. The experimental setup included commercially available polyimide copolymer membranes with molecular weight cut-off (MWCO) values in the range of 150-300 Da, acetone as the solvent, and a working pressure (N(2)) of 3 MPa. The investigation of the membranes revealed that a membrane with a MWCO of 200 Da provided quantitative retention of the Pd catalyst and quantitative recovery of the target product by means of a cross-flow dia-nanofiltration procedure.