Formation and surface properties of raspberry-like silica particles: effect of molecular weight of the coating poly(methacrylic acid) brushes

In this work, silica particles were firstly modified with poly(methyl methacrylate) and then converted to poly(methacrylic acid) (PMAA). The PMAA brushes with different molecular weight were used to modify the seed particles and learn the formation process of the raspberry-like particles. Silica particles with core–shell structure were obtained when the silica seed particles were modified only with carboxyl functional groups. With the increase of the molecular weight of PMAA brushes, uniform raspberry-like silica particles appeared gradually. But when the molecular weight of PMAA brushes was above 136,100, the morphologies became complicated. The electric charge of the polymer brushes was also found to have influence on the final morphologies of the particles. The contact angle (CA) tests showed that films composed of nanoparticles with uniform raspberry-like structures had an average CA of 157.2°, which indicated great prospects in the super-hydrophobic applications.     

Rapid and subnanomolar assay of recombinant human erythropoietin by capillary electrophoresis using NanoOrange precolumn labeling and laser‐induced fluorescence detection

Because of less functionally critical carbohydrate sectors that contributed to the stability, efforts have been made to quantify intact recombinant human erythropoietin. A simple, rapid capillary electrophoresis with laser‐induced fluorescence method for the assay of recombinant human erythropoietin was developed, with a limit of detection of intact recombinant human erythropoietin at subnanomolar concentration (up to 10 ng/mL or 3 × 10^?10 M), which is among the lowest reported. High sensitivity was accomplished by precolumn derivatization with the noncovalent dye NanoOrange. Capillary electrophoresis separation and reaction conditions were carefully manipulated for avoiding microheterogeneity of glycoforms and inhomogeneity of multiple labeling products. The fluorescence signal was linear over the range of 10 ng/mL–10 μg/mL, corresponding to the detection requirement of recombinant human erythropoietin in biofluids and pharmaceutical samples, as demonstrated by a real sample analysis. Although the salt in reaction mixtures showed a detrimental effect on the fluorescence of the derivatives, this method could tolerate a certain amount of salt, extending its application in biofluid analysis. In addition, zero‐order fluorescence emission kinetics was obtained, indicating that the rapid decay of recombinant human erythropoietin was derived from a self‐quenching effect.     

Three-dimensional nonlinear vibration model and fatigue failure mechanism of deepwater test pipe

Nonlinear Dynamics - In deepwater test condition, the riser–test pipe (tubing string) system (RTS) is subject to the vortex-induced effect on riser, flow-induced effect on test pipe and...     

Concise Synthesis of 3-Hydroxy-Δ1.10−12,16-cyclogibberellin 12 Dimethyl Ester—A Trachylobagibberellin Analogue

Abstract

Chemical synthesis of a trachylobagibberellin analogue - 3-hydroxy- δ^1.10?12, 16-cyclogibberellin dimethyl ester 4 from gibberellin acid GA₃ 3 was described herein. The key step is the decomposition of the tosylhydrazone 11 to construct the novel [3.2.1.0.^2.7] octane system.     

A reconstructing approach to end‐to‐end network traffic based on multifractal wavelet model

This paper studies the reconstructing method of end‐to‐end network traffic. Due to the development of current communication networks, our networks become more complex and heterogeneous. Meanwhile, because of time‐varying nature and spatio‐temporal correlations of the end‐to‐end network traffic, to obtain it accurately is a great challenge. We propose to exploit discrete wavelet transforms and multifractal analysis to reconstruct the end‐to‐end network traffic from time–frequency domain. First, its time–frequency properties can be characterized in detail by discrete wavelet transforms. And then, we combine discrete wavelet transforms and multifractal analysis to reconstruct end‐to‐end network traffic from link loads. Furthermore, our method needs to measure end‐to‐end network traffic to build the statistical model named multifractal wavelet model. Finally, simulation results from the real backbone networks suggest that our method can reconstruct the end‐to‐end network traffic more accurately than previous methods. Copyright © 2013 John Wiley & Sons, Ltd.     

Steady-state solutions of a reaction–diffusion system arising from intraguild predation and internal storage

Intraguild predation is added to a mathematical model of competition between two species for a single nutrient with internal storage in the unstirred chemostat. At first, we established the sharp a priori estimates for nonnegative solutions of the system, which assure that all of nonnegative solutions belong to a special cone. The selection of this special cone enables us to apply the topological fixed point theorems in cones to establish the existence of positive solutions. Secondly, existence for positive steady state solutions of intraguild prey and intraguild predator is established in terms of the principal eigenvalues of associated nonlinear eigenvalue problems by means of the degree theory in the special cone. It turns out that positive steady state solutions exist when the associated principal eigenvalues are both negative or both positive.     

Microflotronics: A Flexible,Transparent, Pressure‐Sensitive Microfluidic Film

There is an increasing demand for sensitive, flexible, and low‐cost pressure sensing solutions for health monitoring, wearable sensing, robotic and prosthetic applications. Here, the first flexible and pressure‐sensitive microfluidic film is reported, referred to as a microflotronic, with high transparency and seamless integratability with the state‐of‐the‐art microelectronics. The microflotronic film represents the initial effort to utilize a continuous microfluidic layer as the sensing elements for large‐area dynamic pressure mapping applications, and meanwhile an ultrahigh sensitivity of 0.45 kPa^?1 has been achieved in a compact, flexible, and transparent packaging. The response time of the device is in the millisecond range, which is at least an order of magnitude faster than that of its conventional flexible solid‐state counterparts. In addition, the fabrication process of the device is fully compatible with the industrial‐scale manufacturing of capacitive touchscreen devices and liquid‐crystal displays. The overall device packaging can be as thin as 200 μm with an optical transparency greater than 80%. Several practical applications were successfully demonstrated, including surface topology mapping and dynamic blood pressure monitoring. The microflotronic devices offer an alternative approach to the solid‐state pressure sensors, by offering an unprecedented sensitivity and ultrafast response time in a completely transparent, flexible and adaptive platform.     

Creation of Bifunctional Materials: Improve Electron‐Transporting Ability of Light Emitters Based on AIE‐Active 2,3,4,5‐Tetraphenylsiloles

2,3,4,5‐Tetraphenylsiloles are excellent solid‐state light emitters featured aggregation‐induced emission (AIE) characteristics, but those that can efficiently function as both light‐emitting and electron‐transporting layers in one organic light‐emitting diode (OLED) are much rare. To address this issue, herein, three tailored n‐type light emitters comprised of 2,3,4,5‐tetraphenylsilole and dimesitylboryl functional groups are designed and synthesized. The new siloles are fully characterized by standard spectroscopic and crystallographic methods with satisfactory results. Their thermal stabilities, electronic structures, photophysical properties, electrochemical behaviors and applications in OLEDs are investigated. These new siloles exhibit AIE characteristics with high emission efficiencies in solid films, and possess lower LUMO energy levels than their parents, 2,3,4,5‐tetraphenylsiloles. The double‐layer OLEDs [ITO/NPB (60 nm)/silole (60 nm)/LiF (1 nm)/Al (100 nm)] fabricated by adopting the new siloles as both light emitter and electron transporter afford excellent performances, with high electroluminescence efficiencies up to 13.9 cd A^–1, 4.35% and 11.6 lm W^–1, which are increased greatly relative to those attained from the triple‐layer devices with an additional electron‐transporting layer. These results demonstrate effective access to n‐type solid‐state emissive materials with practical utility.     

应用于CMOS图像传感器中带有失调电压消除功能的电容比值非相关十位循环式模数转换器

A 10-bit ratio-independent switch-capacitor（SC） cyclic analog-to-digital converter（ADC） with offset cancelingforaCMOSimagesensorispresented.TheproposedADCcompletesanN-bitconversionin1.5N clock cycles with one operational amplifier. Combining ratio-independent and polarity swapping techniques, the conversioncharacteristicoftheproposedcyclicADCisinherentlyinsensitivebothtocapacitorratioandtoamplifieroffset voltage. Therefore, the circuit can be realized in a small die area and it is suitable to serve as the column-parallel ADC in CMOS image sensors. A prototype ADC is fabricated in 0.18- m one-poly four-metal CMOS technology.The measured results indicate that the ADC has a signal-to-noise and distortion ratio（SNDR） of 53.6 dB and a DNL of C0：12/0：14 LSB at a conversion rate of 600 kS/s. The standard deviation of the offset variation of the ADC is reduced from 2.5 LSB to 0.5 LSB. Its power dissipation is 250 W with a 1.8 V supply, and its area is0.030.8 mm2.     

高灵敏度表面光学非线性测量法

提出了一种测量非透明材料表面光学非线性的新方法：挡板反射4F测量法。该方法在反射4F相位相干成像系统的基础上,在4F系统的像平面放置一个与系统入射面光阑相匹配的不透明挡板,通过测量不同情况下的反射率,实现对材料光学非线性的测量。详细介绍了该方法的基本原理,并通过数值模拟计算了入射角对测量灵敏度的影响。该方法具有单脉冲测量,可同时得到材料的非线性吸收与折射系数等特点。结果表明,在相同条件下挡板反射4F测量法的灵敏度比反射Z扫描方法高2个数量级。