Methods to micropattern multiple protein components on surfaces under mild conditions are of interest for biosensing, proteomics, and fundamental studies in cell biology. Here, we report on the composition-dependent thin-film solubility behavior of o-nitrobenzyl methacrylate (oNBMA, a protected form of methacrylic acid)/methyl methacrylate (MMA)/poly(ethylene glycol) methacrylate (PEGMA) random terpolymers, materials which are promising as aqueous-processible photoresists. Over a broad range of terpolymer compositions, these materials formed initially water-insoluble films, which, upon UV irradiation, rapidly dissolved in aqueous solutions above a critical pH. This threshold pH ranged from approximately 5-7 depending upon the copolymer composition and decreased as the relative ratio of MMA to PEGMA in the copolymers decreased. In addition, in a narrow window of compositions near 35:0:65 oNBMA/MMA/PEGMA (wt ratio), an inverse behavior was observed: thin films that were initially water soluble became kinetically stable in aqueous solutions after UV exposure. The time for these films to completely dissolve was hours rather than seconds, and the rate of dissolution was both temperature- and pH-dependent. This behavior is consistent with a transient stability imparted by inter- and intramolecular hydrogen bonding in the film. Using copolymers of this composition as negative tone photoresists, we demonstrated patterning of two proteins into two discrete regions of a surface. The selective solubility of the resist copolymer allows the entire patterning process to be completed using only biological buffers as solvents and across a temperature range between 4 and 37 degrees C without subjecting either protein to ultraviolet irradiation or dehydration. These materials are thus of interest for complex surface photopatterning under mild aqueous conditions. 相似文献
Cubic-stabilized ((DyO1.5)x–(WO3)y–(BiO1.5)1 − x − y) electrolytes (DWSB) with much higher conductivity than (ErO1.5)0.2(BiO1.5)0.8, 20ESB, were developed through a double-doping strategy. (DyO1.5)0.08–(WO3)0.04–(BiO1.5)0.88, 8D4WSB, is the highest conductivity composition but underwent the greatest conductivity degradation at 500 °C due to its
low total dopant concentration. The effect of dopant composition on conductivity behavior with time at 500 °C demonstrates
that there is a trade-off between initial conductivity and long-term stability at this temperature. Therefore, it is necessary
to find an optimal total and relative concentration of dopants to provide the enhanced long-term stability needed to make
this DWSB electrolyte system feasible for 500 °C operation. To this end, it was found that (DyO1.5)0.25–(WO3)0.05–(BiO1.5)0.70, 25D5WSB, maintained a conductivity of 0.0068 S/cm without appreciable degradation after annealing at 500 °C for 500 h. Moreover,
since bismuth oxide-based electrolytes do not exhibit any grain boundary impedance, the total conductivity of 25D5WSB is significantly
higher than that of alternate electrolytes (e.g., GDC: Gd0.1Ce0.9O1.95) at this temperature. 相似文献
A new reconstruction method called sampled pattern matching (SPM) was applied to the image reconstruction of an electrical
capacitance computed tomography in powder flow in a vertical pipe for petroleum refinery process. This new method is able
to achieve stable convergence without the use of an empirical value. Experiments were carried out using fluid catalytic cracking
(FCC) catalysts as powder with two air volume flow rates and four powder volume flow rates to measure the capacitance of a
pipe cross section. The SPM method is compared with conventional methods in terms of volume fraction, residual capacitance,
and correlation capacitance. Overall, the SPM method proved superior to conventional methods without any empirical value because
SPM achieves accurate reconstruction by using an objective function that is calculated as the inner product calculation between
the experimental capacitance and the reconstructed image capacitance. 相似文献
Nanopowders of Mo, Ta, and Si were fabricated by high-energy ball milling. A dense nanostructured MoSi2–TaSi2 composite was simultaneously synthesized and sintered by the pulsed current activated heating method within 5 min from mechanically activated powder of Mo, Ta, and Si. A highly-dense MoSi2–TaSi2 composite was produced under simultaneous application of an 80-MPa pressure and the pulsed current. The sintering behavior, mechanical properties, and microstructure of the composite were investigated. 相似文献
This paper investigates the three-dimensional flow of a Sisko fluid over a bidirectional stretching sheet, in a porous medium. By using the effect of Cattaneo-Christov heat flux model, heat transfer analysis is illustrated. Using similarity transformation the governing partial differential equations are transferred into a system of ordinary differential equations that are solved numerically by applying Nachtsheim-Swigert shooting iteration technique along with the 6-th order Runge-Kutta integration scheme. The effect of various physical parameters such as Sisko fluid, ratio parameter,thermal conductivity, porous medium, radiation parameter, Brownian motion, thermophoresis, Prandtl number, and Lewis number are graphically represented. 相似文献
Recent studies have shown that polymersomes templated by microfluidic double‐emulsion possess several advantages such as high monodispersity and encapsulation efficiency compared with those generated based on thin‐film rehydration and electroformation. Stabilizers, including bovine serum albumin (BSA) and polyvinyl alcohol (PVA), have been used to enhance the formation and stability of double emulsions that are used as templates for the generation of polymersomes. In this work, the effect of stabilizers on the mechanical response of double‐emulsion‐templated polymersomes using micropipette aspiration is investigated. It is demonstrated that the existence of stabilizers results in the inelastic response in polymersomes in the early stage of solvent removal. However, aged polymersomes that have little residual solvent show elastic behavior. Polymersomes prepared from PVA‐stabilized double emulsions have noticeably lower area expansion moduli than polymersomes prepared from stabilizer‐free and BSA‐stabilized double emulsions, suggesting that PVA is incorporated in the bilayer membrane of polymersomes.
Despite the reported enhanced electrochemical behavior of graphite anodes due to the addition of NaClO4 salts in to the electrolytes used in lithium battery applications, a detailed investigation upon the effect of addition of
NaPF6 salt in an electrolyte containing 1 M LiPF6 in 1:1 V/V EC:DEC has resulted in inferior electrochemical behavior of graphite, i.e., quite contrast to the reported behavior
of improved effects of addition of NaClO4 into 1 M LiClO4 solution, the addition of 0.22 mol dm−3 NaPF6 salt has been found to reduce the capacities of lithium-ion cells containing 1 M LiPF6 in 1:1 V/V EC:DEC. Towards this study, cells fabricated with and without the addition of 0.22 mol dm−3 NaPF6 in 1 M LiPF6 (1:1 V/V EC:DEC) were subjected to a systematic charging at a constant C/10 rate and discharging of cells at four different
rates, viz., C/5, C/2 and C rates at the end of every 5 cycles. The observed results of the charge-discharge studies up to
15 cycles are discussed in this preliminary communication. 相似文献