Discharge Plasma Assisted Adsorbents for Exhaust Treatment： A Comparative Analysis on Enhancing NOx Removal

An analysis has been made on the discharge plasma coupled with an adsorbent system for NOx removal. The cascaded plasma-adsorbent system may be perceived as a better alternative for the existing adsorbent-based abatement system in the industry. In this study the exhaust is sourced from a diesel generator set. It was observed that better NO removal in a plasma reactor can be made possible by achieving higher average fields and subsequent NO2 removal can be improved using an adsorbent system connected in cascade with the plasma system. The paper describes various findings pertaining to these comparative analyses.     

Investigation on Sodium Benzoate Release from Poly(Butylene Adipate‐Co‐Terephthalate)/Organoclay/Sodium Benzoate Based Nanocomposite Film and Their Antimicrobial Activity

Polymeric nanocomposites embedded with nontoxic antimicrobial agents have recently gained potential industrial significance, mainly for their applicability to preserve food quality and ensure safety. In this study, a poly(butylene adipate‐co‐terephthalate) (PBAT)/organoclay (CMMT) based nanocomposite film doped with sodium benzoate (SB) as antimicrobial agent was prepared by a solution mixing process. A homogenous dispersion of organoclay (cetyltrimethylammonium‐modified montmorillonite [CMMT]) in PBAT matrix was observed by X‐ray diffraction and transmission electron microscopy. PBAT/CMMT nanocomposite film showed higher barrier properties against water and methanol vapor compared to the PBAT film. The release of SB from PBAT and its nanocomposite film was measured and the relevant data were fitted to the Weibull model. The higher values of Weibull's shape factor and scale parameter as corroborated by experimental findings indicated faster rate of SB release from PBAT/CMMT/SB nanocomposite film, when compared to the pristine PBAT film. Bacterial inhibition studies were accomplished against 2 food pathogenic bacteria, Bacillus subtilis and Staphylococcus aureus, by determining the zone of inhibition and corresponding growth profiles. Both bacterial inhibition studies and growth profiles established that PBAT/CMMT/SB demonstrated better antimicrobial activity than PBAT/SB film. Therefore, PBAT/CMMT/SB nanocomposite film can be used for food packaging application as it showed good barrier properties and antimicrobial activity against food pathogenic bacteria.     

ECC-CoAP: Elliptic Curve Cryptography Based Constraint Application Protocol for Internet of Things

Constraint Application Protocol (CoAP), an application layer based protocol, is a compressed version of HTTP protocol that is used for communication between lightweight resource constraint devices in Internet of Things (IoT) network. The CoAP protocol is generally associated with connectionless User Datagram Protocol (UDP) and works based on Representational State Transfer architecture. The CoAP is associated with Datagram Transport Layer Security (DTLS) protocol for establishing a secure session using the existing algorithms like Lightweight Establishment of Secure Session for communication between various IoT devices and remote server. However, several limitations regarding the key management, session establishment and multi-cast message communication within the DTLS layer are present in CoAP. Hence, development of an efficient protocol for secure session establishment of CoAP is required for IoT communication. Thus, to overcome the existing limitations related to key management and multicast security in CoAP, we have proposed an efficient and secure communication scheme to establish secure session key between IoT devices and remote server using lightweight elliptic curve cryptography (ECC). The proposed ECC-based CoAP is referred to as ECC-CoAP that provides a CoAP implementation for authentication in IoT network. A number of well-known cryptographic attacks are analyzed for validating the security strength of the ECC-CoAP and found that all these attacks are well defended. The performance analysis of the ECC-CoAP shows that our scheme is lightweight and secure.

     

Time series analysis of co-polarization phase difference (PPD) for winter field crops using polarimetric C-band SAR data

The utility of time series polarimetric C-band data for vegetation state monitoring was explored to understand the mechanism of growth and phenology for important winter crops in India. Parameters investigated were HH–VV phase difference (co-polarization phase difference, PPD), amplitude ratio, and polarization indices. Data were acquired during the entire growth phase categorized as early, mid/peak vegetative, and post-vegetative /flowering phase. The trend emerging in this study showed a shift in the phase difference distribution for agricultural areas relating to the growth rate for various crops. The time series data set revealed that the PPD is a function of frequency and was directly affected by crop type (planophile or erectophile), vigour, structure, and crop biophysical parameters, particularly biomass. The behaviour of crop biomass with PPD responded differentially across crop architectures and vigour classes. Co-polarization index was found to be a good measure for discrimination in early growth stages while cross-polarization index suited in advanced vegetative stages where geometrical orientation was uniform. The PPD captured the change in frequency distribution resulting in a peaked distribution at sowing changing to smooth, well-spread frequency distribution as the peak vegetation stage approaches. This histogram nature is observed to be gradual for high-biomass crops and peaked in case of the low-biomass crops. It is indicative of the rate of growth; a low peaked normal curve indicates faster growth rate and resulting in high biomass. The amplitude ratio in the later phase of growth as on the third date is similarly altered as in the VV returns from the crop. Intuition of the rate of growth and plant vigour is obtained from the temporal PPD pattern. The current study shows that while phase differences and amplitude ratio carry little information content on a single resolution cell basis, their spatial distribution over a wider time span can be used to derive quantitative relationships between SAR response and crop condition. The synergy of information involving the above parameters were used to derive useful information on the vegetation.     

Control of thermo reversible gelation of methylcellulose using polyethylene glycol and sodium chloride for sustained delivery of ophthalmic drug

The effect of molecular weight of polyethyleneglycol (PEG) and sodium chloride (NaCl) on the gelation temperature of methylcellulose (MC) was studied with the objective to develop a MC based formulation for sustained delivery of ophthalmic drug. The gelation temperature of 1% MC was 60 ± 0.40°C. It was found that the gelation temperature of MC was reduced with the addition of 10% PEG and extent of reduction of gelation temperature was depended on the molecular weight of PEG at same PEG concentration of 10%. The gelation temperature of MC was reduced by 10.4 to 5.9°C with the increasing molecular weight of PEG starting from 400 to 20,000 (M_n ) depending on the method of determination of gelation temperature. To reduce the gelation temperature of MC close to physiological temperature (37°C), 6% NaCl was added in the different MC‐PEG combinations containing different molecular weight of PEG. It was observed that the drug release time increased from 5 to 8 h with the increase in molecular weight of PEG from 400 to 20,000 (M_n ) and this was due to the maximum viscosity and gel strength of MC‐PEG20000‐NaCl ternary combination. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Ground- and Excited-State Proton Transfer in Some o-Hydroxy Aromatic Compounds and Solvent Effect

Proton transfer reaction in the ground and excited state of 4-methyl-2,6-diformyl phenol (MFOH) and some of its derivatives in different nonpolar and polar solvents has been studied using steady-state and nanosecond transient emission spectroscopy at room temperature and 77 K. The stable molecular structure in the ground state is an intramolecularly hydrogen-bonded closed conformer from which the intramolecular proton transfer (ESIPT) takes place in the first excited singlet state in nonpolar solvents. An emission band originates from the proton-transferred enol tautomer of the closed conformer. From a detailed study of the absorption, emission, and excitation spectra in highly polar protic and aprotic solvents, two other conformers have been identified. At 77 K in nonpolar solvents, emission spectra show phosphorescence only in the case of MFOH and 4-methyl-2,6-diamidophenol (MDOH). In the case of other derivatives, such as 4-methyl-2,6-diacetylphenol (MAOH) and 4-methyl-2,6-dicarbomethoxyphenol (MOOH), phosphorescence is observed only in the presence of a strong base, such as trimethylamine. This conversion of fluorescence into phosphorescence is markedly slow in the case of MDOH, MAOH, and MOOH compared to that of MFOH. The relatively larger values of fluorescence lifetimes at 77 K are consistent with our observation. It is proposed that the occurrence of phosphorescence is from an open conformer and is caused by the rotation of the formyl group. From nanosecond measurements and quantum yields of fluorescence, we have estimated the decay rate constants. The fluorescence decay rates are slower in polar than in nonpolar solvents; nonradiative decay rates are always found to be dominant over the radiative ones.     

Synthesis of dendritic polyaniline nanofibers by using soft template of sodium alginate

Highly crystallized polyaniline (PANI) nanofibers were synthesized by oxidative polymerization of aniline in the presence of sodium alginate as a soft template in HCl and ammonium peroxydisulfate (APS) acting as an oxidizing agent. Sodium alginate, in presence of a protonic acid like HCl, formed hydrogen bonds with anilium ions or oligomers. The formed hydrogen bonds provide the driving force to form PANI nanofibers. The nanofibers were separated from the alginate gel by degelling with ammonium hydroxide and during degelling emeraldine salt was converted into emeraldine base form. The polymerized PANI was characterized using ultraviolet (UV)–visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), and scanning electron microscopy (SEM). UV and FTIR spectra showed that the presence of sodium alginate had no effect on the electronic state and backbone structures of the resulting PANI products. It was evident from the XRD analysis that the obtained PANI nanofibers exhibit higher crystalline order. SEM micrographs showed that PANI nanofibers were just like a mat of interwoven twisted nanofibers. After magnification of the SEM image, it was found that most of the nanofibers were interconnected to form ramose structures rather than isolated nanofibers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

An Integrated Approach to Testing Embedded Cores and Interconnects Using Test Access Mechanism (TAM) Switch

The present paper introduces a new strategy for testing embedded cores using Test Access Mechanism (TAM) switches. An algorithm has been proposed for testing the cores using the TAM switch architecture. In addition, a scheme for testing the interconnections between cores in parallel is also presented. Experiments have been carried out on several synthetic SOC benchmarks. Results show significant optimization of area overhead as well as test time.