More Like this

1. Structure and gas transport characteristics of triethylene oxide‐grafted polystyrene‐ b ‐poly(ethylene‐ co ‐butylene)‐ b ‐polystyrene

   https://doi.org/10.1002/pol.20200232  

   Tian, Ding ; Alebrahim, Taliehsadat ; Kline, Gregory K. ; Chen, Liwen ; Lin, Haiqing ; Bae, Chulsung ( September 2020 , Journal of Polymer Science)

   Polymeric membrane‐based gas separation technology has significant advantages compared with traditional amine‐based CO₂separation method. In this work, SEBS block copolymer is used as a polymer matrix to incorporate triethylene oxide (TEO) functionality. The short ethylene oxide segment is chosen to avoid crystallization, which is confirmed by differential scanning calorimetry and wide‐angle X‐ray scattering characterizations. The gas permeability results reveal that CO₂/N₂selectivity increased with increasing content of TEO functional group. The highest CO₂permeability (281 Barrer) and CO₂/N₂selectivity (31) were obtained for the membrane with the highest TEO incorporation (57 mol%). Increasing the TEO content in these copolymers results in an increase in CO₂solubility and a decrease in C₂H₆solubility. For example, as the grafted TEO content increased from 0 to 57 mol%, the CO₂solubility and CO₂/C₂H₆solubility selectivity increased from 0.72 to 1.3 cm³(STP)/cm³atm and 0.47 to 1.3 at 35°C, respectively. The polar ether linkage in TEO‐grafted SEBS copolymers exhibits favorable interaction with CO₂and unfavorable interaction with nonpolar C₂H₆, thus enhancing CO₂/C₂H₆solubility selectivity.

    

   more » « less
2. Si-matched B x Ga 1− x P grown via hybrid solid- and gas-source molecular beam epitaxy

   https://doi.org/10.1063/5.0021493  

   Blumer, Zak H. ; Boyer, Jacob T. ; Blumer, Ari N. ; Lepkowski, Daniel L. ; Grassman, Tyler J. ( September 2020 , Applied Physics Letters)
3. Highly tunable, polarization-engineered two-dimensional electron gas in ε -AlGaO 3 / ε -Ga 2 O 3 heterostructures

   https://doi.org/10.35848/1882-0786/ab9168  

   Ranga, Praneeth ; Cho, Sung Beom ; Mishra, Rohan ; Krishnamoorthy, Sriram ( June 2020 , Applied Physics Express)
4. Directed gas-phase preparation of the elusive phosphinosilylidyne (SiPH 2 , X 2 A′′) and cis / trans phosphinidenesilyl (HSiPH; X 2 A′) radicals under single-collision conditions

   https://doi.org/10.1039/D1CP02812J  

   He, Chao ; Goettl, Shane J. ; Yang, Zhenghai ; Doddipatla, Srinivas ; Kaiser, Ralf I. ; Silva, Mateus Xavier ; Galvão, Breno R. ( September 2021 , Physical Chemistry Chemical Physics)

   The reaction of the D1-silylidyne radical (SiD; X 2 Π) with phosphine (PH 3 ; X 1 A 1 ) was conducted in a crossed molecular beams machine under single collision conditions. Merging of the experimental results with ab initio electronic structure and statistical Rice–Ramsperger–Kassel–Marcus (RRKM) calculations indicates that the reaction is initiated by the barrierless formation of a van der Waals complex (i0) as well as intermediate (i1) formed via the barrierless addition of the SiD radical with its silicon atom to the non-bonding electron pair of phosphorus of the phosphine. Hydrogen shifts from the phosphorous atom to the adjacent silicon atom yield intermediates i2a, i2b, i3; unimolecular decomposition of these intermediates leads eventually to the formation of trans / cis -phosphinidenesilyl (HSiPH, p2/p4) and phosphinosilylidyne (SiPH 2 , p3) via hydrogen deuteride (HD) loss (experiment: 80 ± 11%, RRKM: 68.7%) and d - trans / cis -phosphinidenesilyl (DSiPH, p2′/p4′) plus molecular hydrogen (H 2 ) (experiment: 20 ± 7%, RRKM: 31.3%) through indirect scattering dynamics via tight exit transition states. Overall, the study reveals branching ratios of p2/p4/p2′/p4′ ( trans / cis HSiPH/DSiPH) to p3 (SiPH 2 ) of close to 4 : 1. The present study sheds light on the complex reaction dynamics of the silicon and phosphorous systems involving multiple atomic hydrogen migrations and tight exit transition states, thus opening up a versatile path to access the previously elusive phosphinidenesilyl and phosphinosilylidyne doublet radicals, which represent potential targets of future astronomical searches toward cold molecular clouds (TMC-1), star forming regions (Sgr(B2)), and circumstellar envelopes of carbon rich stars (IRC + 10216). 

   more » « less
5. Stereospecific control of peptide gas-phase ion chemistry with cis and trans cyclo ornithine residues

   https://doi.org/10.1002/jms.4047  

   Marek, Aleš ; Nguyen, Huong T.H. ; Brož, Břetislav ; Tureček, František ( February 2018 , Journal of Mass Spectrometry)