Durable adhesives based on electrospun poly(vinylidene fluoride) fibers

Herein, the fabrication of poly(vinylidene fluoride) (PVDF) fibrous membrane using electrospinning is reported and its use for dry‐adhesive applications is demonstrated. The shear and normal adhesion performance of the samples was investigated using an Instron tensile tester and an atomic force microscope (AFM) respectively. For shear adhesion measurements, the electrospun membrane was finger pressed on to a glass slide and pulled in shear mode using a tensile tester. The thickness of the electrospun membrane was varied and the effect of thickness on shear adhesion was investigated. The shear adhesion strength increased when the thickness of the samples was reduced. Shear adhesion strength of a 200 µm thick sample was determined to be approximately 0.165 N/cm. For normal adhesion measurements, a flat tipless cantilever was used to indent the sample and then retract back to measure the pull‐off force. High shear adhesion strength and normal pull‐off force recorded are attributed to the fine size of the fibers that conform to the asperities present on the surfaces of the glass slide and the AFM cantilever. The durability of the adhesive was also verified by repeating the AFM adhesion measurements over 1000 consecutive attachment–detachment cycles. The pull‐off force was seen to be constant over 1000 attachment–detachment cycles. Our results indicate that these electrospun fibrous membranes can potentially be used as reusable dry‐adhesives. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44393.     

Deterministic Nucleation for Halide Perovskite Thin Films with Large and Uniform Grains

Halide perovskite materials have come to the forefront of optoelectronics recently owing to their excellent light absorbing and emitting properties. Despite their excellent properties there are still problems that need to be overcome such as short operating lifetimes, and an observed hysteresis behavior in their current–voltage characteristics. It is found that these challenges could be overcome by developing a deterministic nucleation process using gold as a nucleation promoter to control the grain size of the perovskite layer. It is shown that this deterministic nucleation process can be expanded across multiple perovskite systems and can be used to achieve extremely uniform and large grain sizes within the perovskite layer. These large perovskite grains exhibit enhanced stability compared to current state‐of‐the‐art nanocrystalline films, and exhibit no hysteresis in their I–V characteristics which is key if commercialization of perovskites is to be realized.     

Synthesis and characterization of bio-based benzoxazine oligomer from cardanol for corrosion resistance application

The Mannich-like condensation of a cardanol, paraformaldehyde, and N,N′-bis(2-aminoethyl)ethane-1,2-diamine were carried out to synthesize the amine functional benzoxazine (Bnz) resin. The amine functionality of Bnz resin was evaluated by physiochemical methods, and the structure was characterized using Fourier transform infrared and ¹H-nuclear magnetic resonance spectroscopy. The added functionality into the Bnz resin backbone was utilized to modify the Bnz resin structure by glycidoxypropyltrimethoxysilane (GPTMS) in various proportions. The results revealed that the silane-modified Bnz coatings have improved mechanical, chemical, and solvent resistance properties as compared to the neat Bnz coating. The gel and water absorption of polyamide-cured coatings also has been evaluated. Furthermore, the cured films have been evaluated for glass transition temperature (T _g) and thermal resistance by differential scanning calorimetry and thermogravimetric analysis, respectively. The corrosion resistance properties were studied by salt spray and electrochemical analysis. It was observed that the highly crosslinked structure of the GPTMS-modified Bnz coatings enhanced the barrier protection to corrosive species.     

Estimating weak ratiometric signals in imaging data. II. Meta-analysis with multiple, dual-channel datasets

Ratiometric fluorescent indicators are used for making quantitative measurements of a variety of physiological variables. Their utility is often limited by noise. This is the second in a series of papers describing statistical methods for denoising ratiometric data with the aim of obtaining improved quantitative estimates of variables of interest. Here, we outline a statistical optimization method that is designed for the analysis of ratiometric imaging data in which multiple measurements have been taken of systems responding to the same stimulation protocol. This method takes advantage of correlated information across multiple datasets for objectively detecting and estimating ratiometric signals. We demonstrate our method by showing results of its application on multiple, ratiometric calcium imaging experiments.     

Anomaly Detection System in Cloud Environment Using Fuzzy Clustering Based ANN

Cloud computing affords lot of resources and computing facilities through Internet. Cloud systems attract many users with its desirable features. In spite of them, Cloud systems may experience severe security issues. Thus, it is essential to create an Intrusion Detection System (IDS) to detect both insider and outsider attacks with high detection accuracy in cloud environment. This work proposes an anomaly detection system at the hypervisor layer named Hypervisor Detector that uses a hybrid algorithm which is a mixture of Fuzzy C-Means clustering algorithm and Artificial Neural Network (FCM-ANN) to improve the accuracy of the detection system. The proposed system is implemented and compared with Naïve Bayes classifier and Classic ANN algorithm. The DARPA’s KDD cup dataset 1999 is used for experiments. Based on extensive theoretical and performance analysis, it is evident that the proposed system is able to detect the anomalies with high detection accuracy and low false alarm rate even for low frequent attacks thereby outperforming Naïve Bayes classifier and Classic ANN.     

Constitutive Photomorphogenic 1 Enhances ER Stress Tolerance in Arabidopsis

Interaction between light signaling and stress response has been recently reported in plants. Here, we investigated the role of CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1), a key regulator of light signaling, in endoplasmic reticulum (ER) stress response in Arabidopsis. The cop1-4 mutant Arabidopsis plants were highly sensitive to ER stress induced by treatment with tunicarmycin (Tm). Interestingly, the abundance of nuclear-localized COP1 increased under ER stress conditions. Complementation of cop1-4 mutant plants with the wild-type or variant types of COP1 revealed that the nuclear localization and dimerization of COP1 are essential for its function in plant ER stress response. Moreover, the protein amount of ELONGATED HYPOCOTYL 5 (HY5), which inhibits bZIP28 to activate the unfolded protein response (UPR), decreased under ER stress conditions in a COP1-dependent manner. Accordingly, the binding of bZIP28 to the BIP3 promoter was reduced in cop1-4 plants and increased in hy5 plants compared with the wild type. Furthermore, introduction of the hy5 mutant locus into the cop1-4 mutant background rescued its ER stress-sensitive phenotype. Altogether, our results suggest that COP1, a negative regulator of light signaling, positively controls ER stress response by partially degrading HY5 in the nucleus.