TY  - JOUR
A1  - Chen, Ye
A1  - Song, Qilei
A1  - Zhao, Junpeng
A1  - Gong, Xiangjun
A1  - Schlaad, Helmut
A1  - Zhang, Guangzhao
T1  - Betulin-Constituted multiblock amphiphiles for broad-spectrum protein resistance
JF  - ACS applied materials & interfaces
N2  - Multiblock-like amphiphilic polyurethanes constituted by poly(ethylene oxide) and biosourced betulin are designed for antifouling and synthesized by a convenient organocatalytic route comprising tandem chain-growth and step-growth polymerizations. The doping density of betulin (D-B) in the polymer chain structure is readily varied by a mixed-initiator strategy. The spin-coated polymer films exhibit unique nanophase separation and protein resistance behaviors. Higher D-B leads to enhanced surface hydrophobicity and, unexpectedly, improved protein resistance. It is found that the surface holds molecular-level heterogeneity when D-B is substantially high due to restricted phase separation; therefore, broad-spectrum protein resistance is achieved despite considerable surface hydrophobicity. As D-B decreases, the distance between adjacent betulin units increases so that hydrophobic nanodomains are formed, which provide enough landing areas for relatively small-sized proteins to adsorb on the surface.
KW  - amphiphilic surface
KW  - antifouling
KW  - multiblock copolymer
KW  - organocatalytic polymerization
KW  - renewable resource
Y1  - 2018
U6  - https://doi.org/10.1021/acsami.7b16255
SN  - 1944-8244
VL  - 10
IS  - 7
SP  - 6593
EP  - 6600
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Chen, Ye
A1  - Loisch, Gregor
A1  - Gross, Matthias
A1  - Jao, Chun-Sung
A1  - Krasilnikov, Mikhail
A1  - Oppelt, Anne
A1  - Osterhoff, Jens
A1  - Pohl, Martin
A1  - Qian, Houjun
A1  - Stephan, Frank
A1  - Vafin, Sergei
T1  - Generation of quasi continuous-wave electron beams in an L-band normal conducting pulsed RF injector for laboratory astrophysics experiments
JF  - Nuclear instruments & methods in physics research : a journal on accelerators, instrumentation and techniques applied to research in nuclear and atomic physics, materials science and related fields in physics ; A, Accelerators, spectrometers, detectors and associated equipment
N2  - We report on an approach to produce quasi continuous-wave (cw) electron beams with an average beam current of milliamperes and a mean beam energy of a few MeV in a pulsed RF injector. Potential applications are in the planned laboratory astrophysics programs at DESY. The beam generation is based on field emission from a specially designed metallic field emitter. A quasi cw beam profile is formed over subsequent RF cycles at the resonance frequency of the gun cavity. This is realized by debunching in a cut disk structure accelerating cavity (booster) downstream of the gun. The peak and average beam currents can be tuned in beam dynamics simulations by adjusting operation conditions of the booster cavity. Optimization of the transverse beam size at specific positions (e.g., entrance of the plasma experiment) is performed by applying magnetic focusing fields provided by solenoids along the beam line. In this paper, the design of a microtip field emitter is introduced and characterized in electromagnetic field simulations in the gun cavity. A series of particle tracking simulations are conducted for multi-parametric optimization of the parameters of the produced quasi cw electron beams. The obtained results will be presented and discussed. In addition, measurements of the parasitic field emission (PFE) current (dark current) in the PITZ gun will be exemplarily shown to distinguish its order of magnitude from the produced beam current by the designed field emitter.
KW  - Cw electron beam
KW  - RF gun
KW  - Booster cavity
KW  - Laboratory astrophysics
KW  - Field emission
KW  - Beam dynamics
Y1  - 2018
U6  - https://doi.org/10.1016/j.nima.2018.06.063
SN  - 0168-9002
SN  - 1872-9576
VL  - 903
SP  - 119
EP  - 125
PB  - Elsevier
CY  - Amsterdam
ER  -