Formation of Porous Polymer Coatings on Complex Substrates Using Vapor Phase Precursors

In this work, porous poly(methacrylic acid) (PMAA) coatings are formed on complex substrates using vapor phase precursors. The porous coatings are created by partially polymerizing solid monomer deposited onto the substrate. The conformality of the porous PMAA coatings is studied on the external and internal surfaces of cylindrical substrates. Flow effects lead to thickness variations in the θ‐direction while thermal gradients and monomer depletion effects lead to thickness variations in the z‐direction. These variations can be reduced by modifying the flow rate of the monomer vapor, by reducing the radiative heat on the substrate, or by increasing the dimension size of the substrate. This work shows that vapor phase processing methods can be a viable alternative to solution phase methods and the observed trends can be utilized in a range of vapor phase technologies to optimize porous coatings for use in tissue engineering, sensors, and separations.

     

Synthesis and in vitro assessment of novel water‐soluble dextran‐docetaxel conjugates as potential pH sensitive system for tumor‐targeted delivery

Docetaxel is a potent taxane agent mostly used in breast, lung, and prostate cancers. Its low water solubility is the major drawback that leads to use of Tween 80 as surfactant and ethanol as solvent in market formulation. But, these excipients cause severe hypersensitivity reactions. In this study, docetaxel was conjugated to biocompatible polymer, dextran 70 kDa, via a pH sensitive linker to enhance solubility and diminish the need of surfactants. Folic acid was also conjugated to dextran to provide targeted delivery. Synthesized conjugates were examined for solubility, hemo‐compatibility, stability, and cytotoxicity on MCF‐7 and MDA‐MB‐231 cell lines. Results showed about 1200‐fold enhancement in water solubility by dextran and 280‐fold by dextran‐folate conjugation. Conjugates released the drug in a pH‐dependent manner and faster hydrolysis was observed in pH 5.4 than physiological pH 7.4. Docetaxel‐dextran conjugates showed proper hemo‐compatibility and presented greater cytotoxicity than docetaxel solution. Higher cytotoxicity was seen in folate conjugated samples and the final conjugates targeted by folate would be suitable novel substitutions for currently marketed formulation. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45457.     

Subjective responses to emotional stimuli during labeling, reappraisal, and distraction.

Although multiple neuroimaging studies suggest that affect labeling (i.e., putting feelings into words) can dampen affect-related responses in the amygdala, the consequences of affect labeling have not been examined in other channels of emotional responding. We conducted four studies examining the effect of affect labeling on self-reported emotional experience. In study one, self-reported distress was lower during affect labeling, compared to passive watching, of negative emotional pictures. Studies two and three added reappraisal and distraction conditions, respectively. Affect labeling showed similar effects on self-reported distress as both of these intentional emotion regulation strategies. In each of the first three studies, however, participant predictions about the effects of affect labeling suggest that unlike reappraisal and distraction, people do not believe affect labeling to be an effective emotion regulation strategy. Even after having the experience of affect labels leading to lower distress, participants still predicted that affect labeling would increase distress in the future. Thus, affect labeling is best described as an incidental emotion regulation process. Finally, study four employed positive emotional pictures and here, affect labeling was associated with diminished self-reported pleasure, relative to passive watching. This suggests that affect labeling tends to dampen affective responses in general, rather than specifically alleviating negative affect. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

A new multi-level trust management framework (MLTM) for solving the invalidity and sparse problems of user feedback ratings in cloud environments

Choosing a trusted cloud service provider (CSP) is a major challenge for cloud users (CUs) in the cloud environment, as many CSPs offer cloud services (CSs) with the same functionality. Trust evaluation of CSPs is often based on information from quality of service (QoS) monitoring and CUs’ feedback ratings. Despite the volume of feedback ratings received in trust management systems, the quality of feedback storage is very low, as many CUs do not send their feedback ratings when using CSs. Additionally, a percentage of existing feedback ratings may not be valid, since some malicious CUs send unfair feedback ratings to change the trust evaluation results. As these lead to poor data quality, the accuracy of trust evaluation results might be affected. To overcome these limitations, this paper proposes a new multi-level trust management framework, which completes previous frameworks by defining new components to improve the data quality of feedback storage. In our framework, new components were defined to solve the invalidity and sparse problems of feedback storage. Certainly, the trust assessment of CSP would be more accurate based on high-quality feedback ratings. The performance of the MLTM was evaluated using two different datasets based on a real Quality of Web Services dataset (QWS) and an artificial data set (Cloud-Armor), whose quality was reduced for the purpose of this study. Analytical values revealed that our proposed approach significantly outperformed other approaches even with the poor data quality of feedback storage.

     

Coordinated Cognitive Tethering in Dense Wireless Areas

This paper examines the resource gain that can be obtained from the creation of clusters of nodes in densely populated areas. A single node within each such cluster is designated as a “hotspot”; all other nodes then communicate with a destination node, such as a base station, through such hotspots. We propose a semi‐distributed algorithm, referred to as coordinated cognitive tethering (CCT), which clusters all nodes and coordinates hotspots to tether over locally available white spaces. CCT performs the following these steps: (a) groups nodes based on a modified k‐means clustering algorithm; (b) assigns white‐space spectrum to each cluster based on a distributed graph‐coloring approach to maximize spectrum reuse, and (c) allocates physical‐layer resources to individual users based on local channel information. Unlike small cells (for example, femtocells and WiFi), this approach does not require any additions to existing infrastructure. In addition to providing parallel service to more users than conventional direct communication in cellular networks, simulation results show that CCT can increase the average battery life of devices by 30%, on average.     

Polyethylene glycol as an epoxy modifier with extremely high toughening effect: Formation of nanoblend morphology

The brittle nature of epoxy polymers is one of their main drawbacks, preventing their widespread applications. In this research article, a new modifier with an extremely toughening effect on brittle epoxy was developed. It was found that introducing low‐molecular‐weight polyethylene glycol (PEG) in the low amounts (up to 10%) into epoxy matrix considerably improves the impact and fracture properties of epoxy thermosetting polymer without attenuating its tensile properties. Epoxy/PEG hybrid containing 10% PEG exhibited an impact strength of 56.3 kJ/m² which is 5.7 times greater than that of pristine epoxy. The fracture strength of 7.7 MPa m^1/2 with 540% increase compared to pure epoxy was also observed for the hybrid material. Morphological, chemical, and thermal properties of epoxy/PEG hybrid were studied using scanning electron microscopy, Fourier transform infrared spectrometry, and differential thermal analysis, respectively, to find out the basic reasons behind such a considerable improvement. A new morphology, consisting uniformly dispersed PEG nanoparticles in the epoxy matrix, was observed for the modified hybrid. This unique morphology for epoxy/PEG was named as nanoblend. The results showed that the formation of nanoblend morphology with strong interaction between epoxy and PEG in the blend structure is responsible for epoxy toughness. POLYM. ENG. SCI., 54:1833–1838, 2014. © 2013 Society of Plastics Engineers     

Electronic behavior of native oxide films on Ti and TiN during 90-day immersion in electrolytes with different pH levels

This work presents the electronic behavior of Ti and TiN thin films when exposed to electrolytes with pH levels of 2,7 and 13 for 90 days.Staircase potentio-electrochemical impedance spectroscopy tests were performed on the 100-nm Ti and TiN monolithic films,and MottSchottky analysis of these tests was used to determine the films' semiconductive behavior and changes in the donor/acceptor density.In addition,the flat-band potential of each film's surface oxide was also characterized.No attempt was made to control oxide formation,and therefore,these tests reflected the native surfaces of these films.While the TiN films exhibited n-type semiconductivity in all electrolytes,the Ti films only showed n-type behavior in the acidic(pH=2) and neutral(pH=7) electrolytes.The semiconductivity of the Ti films transitioned to p-type during exposure to the basic electrolyte(pH=13) after reaching 60 days.Furthermore,there was a significant increase in the donor densities for both Ti and TiN films when immersed in the basic electrolyte relative to the acidic and neutral electrolytes.     

A novel proposal for all-optical compact and fast XOR/XNOR gate based on photonic crystal

In this paper, we aim to design an all-optical device, which can perform XOR and XNOR functions in a single structure. The proposed structure will be realized by cascading two nonlinear resonant rings. The functionality of the proposed structure is based on controlling the optical behaviour of optical rings via optical intensity. The final structure has one bias and two input control ports, along with two output ports. One port acts as an XOR and the other acts as an XNOR gate. The maximum delay times for the XOR and XNOR gates are 1.5 and 2.5?ps, respectively. Therefore, the working bit rates for the XOR and XNOR gates are 666 and 400?Gbit/s, respectively.     

A Fault Detection Scheme for the FPGA Implementation of SHA-1 and SHA-512 Round Computations

The Secure Hash Algorithm is the most popular hash function currently used in many security protocols such as SSL and IPSec. Like other cryptographic algorithms, the hardware implementation of hash functions is of great importance for high speed applications. Because of the iterative structure of hash functions, a single error in their hardware implementation could result in a large number of errors in the final hash value. In this paper, we propose a novel time-redundancy-based fault diagnostic scheme for the implementation of SHA-1 and SHA-512 round computations. This scheme can detect permanent as well as transient faults as opposed to the traditional time redundancy technique which is only capable of detecting transient errors. The proposed design does not impose significant timing overhead to the original implementation of SHA-1 and SHA-512 round computation. We have implemented the proposed design for SHA-1 and SHA-512 on Xilinx xc2p7 FPGA. It is shown that for the proposed fault detection SHA-1 and SHA-512 round computations, there are, respectively, 3% and 10% reduction in the throughput with 58% and 30% area overhead as compared to the original schemes. The fault simulation of the implementation shows that almost 100% fault coverage can be achieved using the proposed scheme for transient and permanent faults.     

Fabrication of chitosan nanoparticles incorporated with Pistacia atlantica subsp. kurdica hulls’ essential oil as a potential antifungal preservative against strawberry grey mould

Essential oil was extracted from Pistacia atlantica subsp. kurdica hulls and encapsulated in chitosan nanoparticles (NPs) by an emulsion-ionic gelation method. A desirable retention rate (43.3–61.5%) of P. atlantica subsp. kurdica hulls’ essential oil (PAHEO) encapsulated in chitosan NPs was confirmed. In addition, the Fourier transform infrared spectroscopy and X-ray diffraction analysis results revealed the success of PAHEO encapsulation. The formed NPs illustrated a shrunk and spherical shape with a size range of 187.2–632.5 nm as indicated by scanning electron microscopy and dynamic light scattering. The encapsulated PAHEO had a high antifungal activity against Botrytis cinerea under both the in vitro and in vivo conditions. It also significantly decreased the incidence and disease severity of grey mould on strawberries during storage. The spoilage process was postponed by the 8th days of storage at 4 °C in the strawberry fruit treated by PAHEO-incorporated chitosan NPs. These findings imply that NP-encapsulated PAHEO will have promising novel applications in food industries.