Graft copolymerization of nitrile monomers onto bleached jute fiber using potassium persulfate system and their textile characteristics

Graft copolymerization of nitrile monomers, such as acrylonitrile and methacrylonitrile, onto bleached jute fiber was carried out by using K₂S₂O₈/FeSO₄ redox system in nitrogen atmosphere and their effect on the textile characteristics was also investigated. Percent graft yield increased with the increase of concentrations of monomer, initiator, and catalyst, reaction time, and reaction temperature up to a certain value, and, thereafter, it decreased. The effect of percent grafting efficiency was similar to that of percent graft yield, except for the monomer concentration. The increase of percent graft yield was dependent on the availability of jute‐macroradicals as well as monomer radicals. Sometimes the predominancy of homopolymerization over grafting and the premature termination of growing grafted chains occurred because of the higher monomer radicals and excess primary radicals, SO₄^?? and ^?OH, from K₂S₂O₈ initiator. The percent graft yield of acrylonitrile and methacrylonitrile was 20.5 and 29.1%, respectively. Higher graft yield for methacrylonitrile might be due to the methyl group present in it. Infrared spectra at 2229–2235 cm^?1 of acrylonitrile‐ and methacrylonitrile‐grafted jute strongly supported the graft formation. Grafting of jute fiber improved the thermal stability, protected from photooxidative degradation, and decreased swellability as well as dyeability, etc. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3622–3629, 2004     

Application of machine vision in improving safety and reliability for gear profile measurement

This research presents a camera-based measurement system which is developed to improve the safety and reliability for gear profile measurement system. Gear profile measurement is vital in precision engineering. To increase the safety and reliability of the precision measurement, application of camera or vision is very useful. Automatic control is also necessary to increase reliability of the measurement system. Normally, gear profiles are measured using contact-based stylus system. During gear profile measurement, human monitoring is required to avoid accident and sometimes we may face great danger regarding safety of our body especially eyes. The stylus is sharp and thin and if it is collided to the gear teeth there is high probability of breaking and scattering the stylus tip. To save time, if the measurement probe scans the gear shape with a speed of 10 mm/s then the issue of safety should be considered highly. The traditional methods for gear measurement are either time consuming or expensive. This paper presents the successful implementation of the camera system in precision measurement which saves time and increases safety and reliability of the measurement with the increment of the measurement performance by increasing production rate. Color-based stylus tracking algorithm is implemented to acquire better reliability of the complete system. Thus, the developed system with vision enhances safety and reliability of the precision measurement.     

Thermal behavior and surface morphology studies on polystyrene grafted sago starch

Polystyrene grafting onto sago starch was carried out by using ceric ammonium nitrate as a redox initiator. The grafted copolymers were characterized by FTIR, thermogravimetry (TGA), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). FTIR spectra analysis of the grafted chain and commercial polystyrene was identical, indicating that styrene was successfully grafted onto sago starch. TGA thermograms and analysis of DSC curves showed that the thermal stability of starch increases as a result of grafting. SEM micrographs showed the deformed prolate ellipsoidal shape of sago starch particles and this shape disappeared in polystyrene grafted sago starch being replaced with a spongy surface with pores. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2053–2058, 2003     

A Low Duty Cycle MAC Protocol for Directional Wireless Sensor Networks

Directional communication in wireless sensor networks minimizes interference and thereby increases reliability and throughput of the network. Hence, directional wireless sensor networks (DWSNs) are fastly attracting the interests of researchers and industry experts around the globe. However, in DWSNs the conventional medium access control protocols face some new challenges including the synchronization among the nodes, directional hidden terminal and deafness problems, etc. For taking the advantages of spatial reusability and increased coverage from directional communications, a low duty cycle directional Medium Access control protocol for mobility based DWSNs, termed as DCD-MAC, is developed in this paper. To reduce energy consumption due to idle listening, duty cycling is extensively used in WSNs. In DCD-MAC, each pair of parent and child sensor nodes performs synchronization with each other before data communication. The nodes in the network schedule their time of data transmissions in such a way that the number of collisions occurred during transmissions from multiple nodes is minimized. The sensor nodes are kept active only when the nodes need to communicate with each other. The DCD-MAC exploits localized information of mobile nodes in a distributed manner and thus it gives weighted fair access of transmission slots to the nodes. As a final point, we have studied the performance of our proposed protocol through extensive simulations in NS-3 and the results show that the DCD-MAC gives better reliability, throughput, end-to-end delay, network lifetime and overhead comparing to the related directional MAC protocols.     

Cooperative Hybrid Spectrum Sharing: A NOMA-based Approach

Non-orthogonal multiple (NOMA) access using successive interference cancellation and cognitive radio are two promising techniques for enhancing the spectrum efficiency and utilization for future wireless communication systems. This paper presents a NOMA-based cooperative hybrid spectrum sharing protocol for cognitive radio networks. A two phase decode-and- forward (DF) relaying scheme in a multi-relay scenario is considered. Each secondary transmitter is grouped into one of the two clusters: a non-cooperative cluster (NCC) and a cooperative cluster (CC). The cluster head (CH) of the CC working as the best DF relay for the primary system is permitted to transmit its own signal superimposed on the primary signal using a NOMA approach in exchange for cooperation. On the other hand, the CH of the NCC transmits in parallel with the primary system satisfying a predefined peak transmit power and peak interference power constraints that guarantee a given primary quality of the service requirement. It is demonstrated that the performances of both the primary and secondary systems increase with the increasing number of secondary nodes. The simulation and theoretical results affirm the efficacy of the proposed protocol compared to the traditional overlay and underlay models in terms of the outage probability and the ergodic capacity.     

SC-LDPC Code Design for Half-Duplex Relay Channels

This paper studies code design for the half-duplex relay channel when the transmissions take place over binary input additive white Gaussian noise (BIAWGN) channels. Using the decode-forward relay protocol, we design the relay code based on a spatially coupled low-density parity-check (SC-LDPC) code. We show a low complexity density evolution analysis for the proposed relay code. From the density evolution results, we observe that the proposed spatially coupled relay code achieves a capacity approaching performance. We also observe that the proposed code outperforms existing optimized LDPC relay codes. Through simulation results, we evaluate the finite-length performance of the proposed code.

     

A Single-Framework Synthetic Antibody Library Containing a Combination of Canonical and Variable Complementarity-Determining Regions

Synthetic antibody libraries have been used to generate antibodies with favorable biophysical and pharmacological properties. Here, we describe the design, construction, and validation of a phage-displayed antigen-binding fragment (Fab) library built on a modified trastuzumab framework with four fixed and two diversified complementarity-determining regions (CDRs). CDRs L1, L2, H1, and H2 were fixed to preserve the most commonly observed “canonical” CDR conformation preferred by the modified trastuzumab Fab framework. The library diversity was engineered within CDRs L3 and H3 by use of custom-designed trinucleotide phosphoramidite mixes and biased towards human antibody CDR sequences. The library contained ≈7.6 billion unique Fabs, and >95 % of the library correctly encoded both diversified CDR sequences. We used this library to conduct selections against the human epidermal growth factor receptor-3 extracellular domain (HER3-ECD) and compared the CDR diversity of the naïve library and the anti-HER3 selection pool by use of next-generation sequencing. The most commonly observed CDR combination isolated, named Her3-3, was overexpressed and purified in Fab and immunoglobulin G (IgG) formats. Fab HER3-3 bound to HER3-ECD with a K_D value of 2.14 nm and recognized cell-surface HER3. Although HER3-3 IgG bound to cell-surface HER3, it did not inhibit the proliferation of HER3-positive cells. Near-infrared imaging showed that Fab HER3-3 selectively accumulated in a murine HER3-postive xenograft, thus providing a lead for the development of HER3 imaging probes.     

Privacy-Preserving Data Communication Through Secure Multi-Party Computation in Healthcare Sensor Cloud

In recent years, wireless medical sensor networks meet the web to enable exciting healthcare applications that require data communication over the Internet. Often these applications suffer from data disclosure due to malicious users’ activities. To prevent such data disclosure in the healthcare systems, many public key cryptographic techniques have been used. However, most of them are too expensive to implement in the web-enabled wireless medical sensor networks. In 2013, Xun et al. introduced a lightweight encryption algorithm to protect communication between the sensor node and the data servers. Their scheme is based on the Sharemind framework. However, Sharemind framework has a limitation on the number of data storage servers (ie., three servers only). In addition, Xun et al’s scheme does not support privacy-preserving patient data analysis for distributed databases of different hospitals. In this paper, we introduce a new practical approach to prevent data disclosure from inside attack. Our new proposal is based on FairplayMP framework which enables programmers who are not experts in the theory of secure computation to implement such protocols. In addition, it support any number of n participants and is suitable for distributed environments. Moreover, in our new scheme, each sensor node needs only one secret key stored in advance to communicate with n different data servers, whereas three secret keys are embedded in advance into each sensor in order to communicate with three data servers in Xun et al’s scheme.     

Effects of TiO2 and GO nanoparticles on the thermomechanical properties of bioactive poly-HEMA nanocomposites

Iranian Polymer Journal - Bioactive polymeric nanocomposites are indispensable materials and have received great attention owing to their diverse applications in human body. In this study, a...     

Metabolite Profiling of Manilkara zapota L. Leaves by High-Resolution Mass Spectrometry Coupled with ESI and APCI and In Vitro Antioxidant Activity, α-Glucosidase,and Elastase Inhibition Assays

High-resolution mass spectrometry equipped with electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) sources was used to enhance the characterization of phytochemicals of ethanol extracts of Manilkara zapota L. leaves (ZLE). Sugar compounds, dicarboxylic acids, compounds of phenolic acids and flavonoids groups, and other phytochemicals were detected from the leaves. Antioxidant activity and inhibition potentiality of ZLE against α-glucosidase enzyme, and elastase enzyme activities were evaluated in in vitro analysis. ZLE significantly inhibited activities of α-glucosidase enzyme at a lower concentration (IC₅₀ 2.51 ± 0.15 µg/mL). Glucose uptake in C2C12 cells was significantly enhanced by 42.13 ± 0.15% following the treatment with ZLE at 30 µg/mL. It also exhibited potential antioxidant activities and elastase enzyme inhibition activity (IC₅₀ 27.51 ± 1.70 µg/mL). Atmospheric pressure chemical ionization mass spectrometry (APCI–MS) detected more m/z peaks than electrospray ionization mass spectrometry (ESI–MS), and both ionization techniques illustrated the biological activities of the detected compounds more thoroughly compared to single-mode analysis. Our findings suggest that APCI along with ESI is a potential ionization technique for metabolite profiling, and ZLE has the potential in managing diabetes by inhibiting α-glucosidase activity and enhancing glucose uptake.