Phase‐transfer‐agent‐aided polymerization and graft copolymerization of acrylamide

The use of phase‐transfer catalysts, with water‐insoluble initiators, for polymerization and graft copolymerization reactions was explored. The polymerization of a water‐soluble vinyl monomer, acrylamide (AAm), and the graft copolymerization of AAm onto a water‐insoluble polymer backbone, isotactic polypropylene (IPP), with a water‐insoluble initiator, benzoyl peroxide (BPO), and a phase‐transfer catalyst, tetrabutyl ammonium bromide (Bu₄N⁺Br^?), were carried out in a water/xylene binary solvent system. The conversion percentage of AAm into polyacrylamide (PAAm) and the percentage of grafting of AAm onto IPP were determined as functions of various reaction parameters, such as the BPO, AAm, and phase‐transfer‐catalyst concentrations, the amounts of water and xylene in the water/xylene mixture, the time, and the temperature. The graft copolymer, IPP‐g‐PAAm, was characterized with IR spectroscopy and thermogravimetric analysis. By a comparison of the results of the phase‐transfer‐catalyzed graft copolymerization of AAm onto IPP and the preirradiation method, it was observed that the optimum reaction conditions were milder for the phase‐transfer‐catalyst‐aided graft copolymerization. Milder reaction conditions, including the temperature, the time of reaction, and a moderate initiator (BPO), in comparison with high‐energy γ‐rays, led to better quality products, and the reaction proceeded smoothly with high productivity. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2364–2375, 2004     

Energy Balanced Model for Lifetime Maximization in Randomly Distributed Wireless Sensor Networks

In this paper, an energy balanced model (EBM) for lifetime maximization for a randomly distributed sensor network is proposed. The lifetime of a sensor network depends on the rate of energy depletion caused by multiple factors, such as load imbalance, sensor deployment distribution, scheduling, transmission power control, and routing. Therefore, in this work, we have developed a mathematical model for analysis of load imbalance under uniform and accumulated data flow. Based on this analysis, we developed a model to rationalize energy distribution among the sensors for enhancing the lifetime of the network. To realize the proposed EBM, three algorithms—annulus formation, connectivity ensured routing and coverage preserved scheduling have been proposed. The proposed model has been simulated in ns-2 and results are compared with Energy-Balanced Transmission Policy and Energy Balancing and unequal Clustering Algorithm. Lifetime has been measured in terms of the time duration for which the network provides satisfactory level of coverage and data delivery ratio. EBM outperform both the existing models. In our model the variance of residual energy distribution among the sensors is lower than other two models. This validated the essence of energy rationalization hypothesized by our model.     

Folate-conjugated albumin nanoparticles for rheumatoid arthritis-targeted delivery of etoricoxib

Objective: The present study discusses folic acid-etoricoxib-bovine serum albumin nanoparticles (F-ETX-NPs) using folic acid as an over expressed folate receptor ligand for activated macrophages in targeting of rheumatoid arthritis.

Materials and methods: For this purpose etoricoxib-loaded BSA nanoparticles (ETX-NPs) were prepared by desolvation method and activated folic acid conjugation with free amine group of BSA was confirmed by FTIR study and zeta potential measurements.

Results: The F-ETX-NPs showed spherical in shape with 215.8?±?3.2?nm average size?+?7.8?mV zeta potential, 72?±?1.3% etoricoxib entrapment efficiency and showed 93.1?±?2.2% cumulative etoricoxib release upto 72?h. The etoricoxib concentration from F-ETX-NPs was found to be 9.67?±?0.34?µg/g in inflamed joint after 24?h administration revealed remarkably targeting potential to the activated macrophages cells and keep at a high level during the experiment.

Discussion and conclusion: These results suggest that F-ETX-NPs are potentially vector for activated macrophages cells targeting of rheumatoid arthritis.     

A power law approach to orifice flow rate calibration

Although standards for orifice flow meter design, installation, and calibration are supported herein, noncompliant devices exist in many pilot-, lab-scale, and on-board applications. For these, a common calibration practice is to preserve the ideal square root relation and determine a device specific discharge coefficient value. This work provides theoretical and empirical analyses to support relaxing the square root relation between orifice pressure drop and flow rate for noncompliant devices. The resulting power law relation is shown to improve accuracy, precision, and rangeability. Whether a device specific square root or power law model is used, it requires off-line or in-line calibration data. As such, a power law calibration model may only be useful for on-board and small-scale applications.     

Chitosan: Application in tissue engineering and skin grafting

Tissue Engineering and skin grafting, an essential part of regenerative medicine is one of the fastest growing biomedical fields which could offer an important therapeutic strategy for management of hard to heal wounds. 2D and 3D polymeric scaffolds are prerequisites in this field to promote cell adhesion, proliferation and tissue regeneration. Convergence of technology and research has successfully unveiled unknown properties of Chitosan as a bioactive polymer. Natural abundance, cost effectiveness, biodegradability, biocompatibility and wound healing capabilities of chitosan and its derivatives has drawn the attention of many researchers for its use as an alternative for fabrication of a scaffold in tissue engineering and skin graft. However lower mechanical strength and solubility has limited its application in the biomedical field. It has been found that the derivatization and combination with other polymers can successfully overcome these limitations. This review focuses on the applicability of chitosan and its derivatives in combination with other polymers in tissue engineering and skin grafting along with the novel scaffold fabrication techniques. Studies so far have demonstrated the potential of chitosan and its derivative as a scaffold in the field of regenerative medicine. However, even if the promising results obtained from in-vitro and preclinical studies prove the efficacy of chitosan scaffolds it still has a long way to go to be used in clinical set ups.     

The feasibility of a novel limited field of view spiral cine DENSE sequence to assess myocardial strain in dilated cardiomyopathy

Objective

Develop an accelerated cine displacement encoding with stimulated echoes (DENSE) cardiovascular magnetic resonance (CMR) sequence to enable clinically feasible myocardial strain evaluation in patients with dilated cardiomyopathy (DCM).

Materials and methods

A spiral cine DENSE sequence was modified by limiting the field of view in two dimensions using in-plane slice-selective pulses in the stimulated echo. This reduced breath hold duration from 20RR to 14RR intervals. Following phantom and pilot studies, the feasibility of the sequence to assess peak radial, circumferential, and longitudinal strain was tested in control subjects (n = 18) and then applied in DCM patients (n = 29).

Results

DENSE acquisition was possible in all participants. Elements of the data were not analysable in 1 control (6%) and 4 DCM r(14%) subjects due to off-resonance or susceptibility artefacts and low signal-to-noise ratio. Peak radial, circumferential, short-axis contour strain and longitudinal strain was reduced in DCM patients (p < 0.001 vs. controls) and strain measurements correlated with left ventricular ejection fraction (with circumferential strain r = − 0.79, p < 0.0001; with vertical long-axis strain r = − 0.76, p < 0.0001). All strain measurements had good inter-observer agreement (ICC > 0.80), except peak radial strain.

Discussion

We demonstrate the feasibility of CMR strain assessment in healthy controls and DCM patients using an accelerated cine DENSE technique. This may facilitate integration of strain assessment into routine CMR studies.

     

Study of C<Subscript>2</Subscript>–C<Subscript>5</Subscript> Non-methane Hydrocarbons and Their Ozone Formation Potential at Bhubaneswar,an Eastern Coastal Site in India

A preliminary study has been taken up to evaluate the NHHCs concentration and their effect on atmospheric chemistry at Bhubaneswar for the very first time during winter months when pollution load is prevalent. For this purpose ambient air samples were collected during a period of 3 months (Dec 2013–Feb 2014). The samples were analyzed for C₂–C₅ light non-methane hydrocarbons (NMHCs) using a gas chromatograph with a thermal desorption system. It was observed that level of NMHCs over the measurement site was lower in comparison to other urban locations within India but higher in comparison to Bay of Bengal. Statistical interpretation suggests a non-significant variation of NMHCs concentration between the observation months. Diurnal observations revealed a higher concentration of both n-pentane and i-pentane which was mostly attributed to solvent evaporation. Liquefied petroleum gas usage is believed to be a major contributor to the mixing ratios of propane (1.5 ppbv) and butane (0.027 ppbv) while ethane and ethylene emissions were attributed to traffic volume and vehicular exhausts. The propylene-equivalent and ozone formation potential of NMHCs have also been calculated in order to find out their OH reactivity and contribution to the photochemical ozone formation. Relative humidity was also observed to have a significant correlation with NMHCs concentration. Variation of total non-methane hydrocarbons (TNMHCs) with ozone and CO suggest the role of TNMHC as precursor for ozone formation.