氙在活性炭纤维吸附床上穿透的动力学模型

研究了氙在活性炭纤维吸附床上的穿透特性,采用Boltzmann分布函数理论模拟了穿透曲线,根据Boltzmann函数曲线推导了穿透时间方程,给出了半穿透时间的理论表达式,较好地解释了实验数据。     

A Novel Composite Poly-p-Phenylenebenzobisoxazole (PBO) Fiber Including Molecularly-Dispersed Copper Phthalocyanine in the Structure

The possibility to make a composite poly-p-phenylenebenzobisoxazole (PBO) fiber including a second component without distorting its original structures and mechanical properties was examined. Copper phthalocyanine was found to fulfill the above-mentioned condition and can be dispersed in the fiber molecularly. It was shown that part of the embedded copper phthalocyanine can be aligned one-dimensionally with periodicity along the fiber axis in the fiber. The color of the resultant fiber was dark blue, which is different from the original fiber having its yellowish golden color. According to X-ray diffraction analysis the preferential orientation of the a-axis of the PBO crystal was slightly more oriented by the addition of copper pthalocyanine than that of the pure PBO fiber, but the crystal size of PBO wasn't also affected. We thus show the possibility of adding a second material that can add additional properties to the fiber, but keeping the original high mechanical properties and oriented structures.     

Distributed fiber sensing system with wide frequency response and accurate location

A distributed fiber sensing system merging Mach–Zehnder interferometer and phase-sensitive optical time domain reflectometer (Φ-OTDR) is demonstrated for vibration measurement, which requires wide frequency response and accurate location. Two narrow line-width lasers with delicately different wavelengths are used to constitute the interferometer and reflectometer respectively. A narrow band Fiber Bragg Grating is responsible for separating the two wavelengths. In addition, heterodyne detection is applied to maintain the signal to noise rate of the locating signal. Experiment results show that the novel system has a wide frequency from 1 Hz to 50 MHz, limited by the sample frequency of data acquisition card, and a spatial resolution of 20 m, according to 200 ns pulse width, along 2.5 km fiber link.     

SNR enhancement for composite application using multiple Doppler vibrometers based laser ultrasonic propagation imager

In recent years, the technology of using laser ultrasonic propagation imaging for damage visualization of composite structures were applied to real-world applications. Among many choices of sensor for the Ultrasonic Propagation Imager, the laser interferometry has several advantages: it is non-invasive, and portable, and with extraordinarily long-range measurement. However, the critical issue with interferometry sensing is its low signal-to-noise ratio (SNR), where the background noise can mask the damage-induced waves and making it impossible to identify the damages, especially in composite structures. In this paper, we propose a hardware-based SNR enhancement technique using multiple Laser Doppler Vibrometers (LDVs). The out-of-plane mode of ultrasonic signals are measured by multiple LDVs at a common sensing point and then averaged in real time. We showed that the SNR enhancement in experiments was consistent with the theoretical prediction, and also the test results showed a clear improvement for damage visualization of structures using Ultrasonic Wave Propagation Imaging and Ultrasonic Wavenumber Imaging algorithms.     

Applications of near infrared spectroscopy in cotton impurity and fiber quality detection: A review

Near infrared spectroscopy (NIRS) is an emerging, non-invasive, multi-index, simple preparation of sample process analytical technique suitable for cotton quality assessment. Cotton impurities not only affect the quality of seed cotton and lint cotton but also the quality of textiles. These impurities can occur during harvest and in the stage of postharvest handing, especially during pack house operations. In such a global and competitive marketplace, it is necessary to explore rapid, accurate, and precise cotton quality measurement techniques which require less expensive instrumentation, exhibit increased flexibility versatility, and perform both laboratory measurements and non-laboratory (at-line or field) measurements. Some reports have been published on the use of NIRS technology for inspecting cotton impurity contents, micronaire, and cotton fiber quality. This article condenses a representative selection of recent research in order to observe the significant progresses in how NIRS technology is applied to inspection of cotton impurity and cotton fiber. Additionally, the drawbacks and obstacles of NIRS for quality measurement in cotton are summarized and the trends are discussed.     

Wear behavior of Palmyra palm leaf stalk fiber (PPLSF) reinforced polyester composites

The effect of alkali treatment and fiber length on the wear performance of the Palmyra palm leaf stalk fiber (PPLSF)–polyester composites and the possibilities for using PPLSF in wear resistance applications were explored at different speeds and normal loads for constant sliding distance using pin on disk wear tester as per the ASTM G99 standard. Unsaturated polyester was used as matrix, and composites were prepared by molding in an open mold and pouring the resin. It was observed that wear loss and coefficient of friction reduced due to reinforcement of PPLSF. Reinforcing alkali-treated PPLSF in the matrix has further reduced the wear loss and coefficient of friction. At high speed and high load condition considered in this study shows that the wear loss and coefficient of friction were reduced by 64 and 22%, respectively, for alkali-treated fiber composites compared with untreated fiber composites. The effect of fiber length on the wear performance was also evaluated and optimal set of parameters that would result in minimum wear loss and coefficient of friction was determined by design of experimental method using Taguchi’s orthogonal array. The surface morphology of the composites after wear tests was examined using scanning electron microscopy to analyze the mechanism of wear.     

Banana fiber strands–reinforced polymer matrix composites

Banana fiber (BF)-reinforced low-density polyethylene (LDPE) unidirectional composites were fabricated by the compression molding process with 40 wt% fiber loading. The fibers were modified with methylacrylate (MA) mixed with methanol (MeOH) along with 2% benzyl peroxide under thermal curing method at different temperatures (50–90 °C) for different curing times (10–50 min) in order to have better compatibility with the matrix. The effect of fiber surface modification on the mechanical properties (tensile and impact properties) of the composites were evaluated. Monomer concentration, curing temperature, and curing time were optimized in terms of polymer loading and mechanical properties. The mechanical properties were found to be improved based on the improved interaction between the reinforcement and the matrix. Optimized BFs were again treated with 2–5 wt% starch solutions and composites made of 4% starch treated BF showed the highest mechanical properties than that of MA treated composites. Scanning electron microscopy (SEM) was performed to get an insight into the morphology of the composites. Water uptake and soil degradation test of the composites were also investigated.     

Effect of carbon fiber surface functionality on the moisture absorption behavior of carbon fiber/epoxy resin composites

Polyacrylonitrile (PAN)‐based carbon fibers were electrochemically oxidized in aqueous ammonium bicarbonate with increasing current density. The electrochemical treatment led to significant changes of surface physical properties and chemical structures. The oxidized fibers showed much cleaner surfaces and increased levels of oxygen functionalities. However, it was found that there was no correlation between surface roughness and the fiber/resin bond strength, i.e. mechanical interlocking did not play a major role in fiber/resin adhesion. Increases in surface chemical functionality resulted in improved fiber/resin bonding and increased interlaminar shear strength (ILSS) of carbon fiber reinforced epoxy composites. The relationship between fiber surface functionality and the hydrothermal aging behavior of carbon fiber/epoxy composites was investigated. The existence of free volume resulted from poor wetting of carbon fibers by the epoxy matrix and the interfacial chemical structure were the governing factors in the moisture absorption process of carbon fiber/epoxy composites. Copyright © 2016 John Wiley & Sons, Ltd.     

Capillary electrophoresis coupled with in‐column fiber‐optic laser‐induced fluorescence detection for the rapid separation of neodymium

In this study, in‐column fiber‐optic (ICFO) laser‐induced fluorescence (LIF) detection technique is coupled with capillary electrophoresis (CE) for the rapid separation of neodymium for the first time. The effects of buffer concentration, buffer pH, and separation voltage on the CE behaviors, including electrophoretic efficiency and detection sensitivity, are investigated in detail. Under the optimal condition determined in this study (15 mM borate buffer, pH 10.50, separation voltage 24 kV), neodymium could be separated effectively from the neighboring lanthanides (praseodymium and samarium) within several minutes, and the limit of detection for neodymium is estimated to be at the ppt level. The ICFO‐LIF‐CE system assembled in this study exhibits unique performance characteristics such as low cost and flexibility. Meanwhile, the separation efficiency and detection sensitivity of the assembled CE system are comparable to or somewhat better than those obtained in the previous traditional CE systems, indicating the potential of the assembled CE system for practical applications in the fields of spent nuclear fuel analysis, nuclear waste disposal/treatment, and nuclear forensics.     

Electrospun Gelatin Fibers with a Multiple Release of Antibiotics Accelerate Dermal Regeneration in Infected Deep Burns

Electrospun fibers of hydrophilic polymers meet challenges in a rapid degradation of fiber matrices and discharge of antibiotics to comply with requirements of infection control as a dermal regeneration template. In the current study, a pH conversion process is initially developed to ensure fluent electrospinning, an efficient in situ cross‐linking of electrospun gelatin fibers with oxidized alginate and simultaneous loading of gentamicin sulfate (GS) and hydrophobic ciprofloxacin into fibers. The dual drug‐loaded fibers indicate a complete release of GS during 6 d and a sustained release of ciprofloxacin for over three weeks, and the antibiotics release indicates significant growth inhibitions on Pseudomonas aeruginosa and Staphylococcus epidermidis. The wound healing efficacy is evaluated on a deep burn model infected with 10⁸ CFU of P. aeruginosa. Compared with fibers with loaded individual drugs, the concomitant release of GS and ciprofloxacin significantly reduces the bacteria numbers in wound and livers, at around 2.30 × 10⁵ and 1.25 × 10³ CFU after 3 d, respectively. The wound re‐epithelization, blood vessel formation, collagen deposition, and tissue remodeling process are accelerated with a complete healing observed after 21 d. This study provides a feasible strategy to design cross‐linked hydrophilic fibers with an extended drug release for biomedical applications.