Simulative analysis of co-existing 2.5 G/10 G asymmetric XG-PON system using RZ and NRZ data formats

In this paper, a fiber optic communication system has been employed using co-existing 10 G/2.5 G asymmetric gigabit passive optical network (XG-PON) architecture. In this system, bidirectional optical fiber has been used for upstream and downstream data transmission. The system performance has been investigated for non-return-to-zero (NRZ) and return-to-zero (RZ) data formats operating at varying bit rates by varying the length of the fiber for analyzing the feasibility of this co-existence. The results have been compared for NRZ and RZ formats for upstream and downstream data in terms of Q value and eye opening. It is observed that RZ modulation format is superior as compared to conventional NRZ format and the faithful transmission of signal has been carried up to 90 km at 1577 nm for downstream and 140 km at 1270 nm for upstream.     

Protein PEGylation attenuates adsorption and aggregation on a negatively charged and moderately hydrophobic polymer surface

Covalent grafting of poly(ethylene glycol) chains to proteins ("PEGylation") is emerging as an effective technique to increase the in vivo circulation time and efficacy of protein drugs. PEGylated protein adsorption at a variety of solid/aqueous interfaces is a critical aspect of their manufacture, storage, and delivery. A special category of block copolymer, PEGylated proteins have one or more water-soluble linear polymer (PEG) blocks and a single globular protein block that each exert distinct intermolecular and surface interaction forces. We report the impact of PEGylation on protein adsorption at the interface between aqueous solutions and solid films of poly(lactide-co-glycolide) (PLG), a moderately hydrophobic and negatively charged polymer. Using the model protein lysozyme with controlled degrees of PEGylation, we employ total internal reflection fluorescence techniques to measure adsorption isotherms, adsorption reversibility, and the extent of surface-induced aggregation. Lysozyme PEGylation reduces the extent of protein adsorption and surface-induced aggregation and increases the reversibility of adsorption compared to the unconjugated protein. Results are interpreted in terms of steric forces among grafted PEG chains and their effects on protein-protein interactions and protein orientation on the surface.     

Enhanced electrical properties of CuO:CoO decorated with Sm2O3 nanostructure for high-performance supercapacitor

Journal of Solid State Electrochemistry - In the present investigation, we have synthesized samarium (Sm) nanoparticles (NPs) and anchored them onto the surface of CuO:CoO nanostructure (NS) by...     

Development of an amperometric sulfite biosensor based on a gold nanoparticles/chitosan/multiwalled carbon nanotubes/polyaniline-modified gold electrode

A sulfite oxidase (SOx) purified from leaves of Syzygium cumini (Jamun) was immobilized covalently onto a gold nanoparticles (AuNPs)/chitosan (CHIT)/carboxylated multiwalled carbon nanotubes (cMWCNTs)/polyaniline (PANI) composite that was electrodeposited onto the surface of a gold (Au) electrode. A novel and highly sensitive sulfite biosensor was developed that used this enzyme electrode (SOx/AuNPs/CHIT/cMWCNT/PANI/Au) as the working electrode, Ag/AgCl as the standard electrode, and Pt wire as the auxiliary electrode. The modified electrode was characterized by Fourier transform infrared (FTIR) spectroscopy, cyclic voltammetry (CV), scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS) before and after the immobilization of the SOx. The sensor produced its optimum response within 3 s when operated at 50 mVs⁻¹ in 0.1 M phosphate buffer, pH 7.0, and at 35 °C. The linear range and detection limit of the sensor were 0.75–400 μM and 0.5 μM (S/N = 3), respectively. The biosensor was employed to determine sulfite levels in fruit juices and alcoholic beverages. The enzyme electrode was used 300 times over a period of three months when stored at 4 °C.     

Performance studies of compact GGAG:Ce,B thermal neutron detector coupled to Si-based photosensors

Pramana - This work concerns the modelling of the dynamics of polarisation of a centrosymmetric material subjected to an amplitude-modulated excitation (AME). The dynamic equation obtained for the...     

Measuring Peak Capacity of Reversed-Phase Columns for Small Molecule Compounds Under Gradient Elution

The conventional approach to the measurement of peak capacity of reserved-phase columns under gradient elution assumes that all peaks have constant peak width, but this assumption can lead to inaccurate measurement of peak capacity. An integration approach employing a series of alkylphenones as model compounds was employed to more accurately measure the peak capacity for small molecule compounds under gradient elution. The base peak width of alkylphenones was plotted against retention time and a peak width function over retention time was established by polynomial regression. The peak capacity was then calculated by integrating the inverse of the peak width function over a gradient window. Compared to the conventional method, the integration method is not based on the assumption of equal peak width, thus providing a more accurate measurement of the peak capacity of reserved-phase columns, especially shorter ones packed with sub-2 μm particles under gradient elution.     

Minimization of self-steepening of ultra short higher-order soliton pulse at 40 Gb/s by the optimization of initial frequency chirp

In this paper, the decay of first- and second-order ultra short pulses of the order of 50 fs due to self-steepening (SS) effect has been numerically investigated for a 40 Gb/s optical soliton system including the impact of third-order dispersion (TOD). It has been observed that the prechirp (both positive and negative) in the pulse can counteract the SS effect and improve compensation performance for the distortions .The critical positive prechirp value is found to be 1.4 and the negative prechirp is 1.2, beyond which the soliton pulse is unstable.     

5 × 10 Gbps WDM-CAP-PON based on frequency comb using OFDM with blue LD

Presently, optical access networks are in great demand to meet the bandwidth requirement due to rapid growth in high speed applications for smart devices, cloud computing, big data analysis and other 5G applications. In this paper, 5?×?10 Gb/s wavelength division multiplexing carrier-less amplitude phase modulation-passive optical network (WDM-CAP-PON) with frequency comb is proposed and demonstrated. Also, 450 nm blue laser diode having bandwidth 0.8 GHz is used for visible light communication using 6 m FSO link to support cost effective high data rate optical network. The WDM-CAP-PON employing orthogonal frequency division multiplexing has been analysed in terms of tolerance to the fiber non-linearities through the effect of variations in launch power (??5 to 4 dBm), datarate (2.5–40 Gb/s) and distance (20–110 km) on Q-factor and error vector magnitude (EVM%) by considering pre-, post- and symmetrical-dispersion compensation schemes. It is reported that post-compensation is superior to pre- and symmetrical-compensation schemes to achieve the minimum 3.8?×?10^?3 BER under 7% forward error correction (FEC). The faithful transmission distance achieved for 10 Gb/s WDM-CAP-PON using post dispersion compensation scheme is 110 km.     

Auditory-visual speech perception in normal-hearing and cochlear-implant listeners

The present study evaluated auditory-visual speech perception in cochlear-implant users as well as normal-hearing and simulated-implant controls to delineate relative contributions of sensory experience and cues. Auditory-only, visual-only, or auditory-visual speech perception was examined in the context of categorical perception, in which an animated face mouthing ba, da, or ga was paired with synthesized phonemes from an 11-token auditory continuum. A three-alternative, forced-choice method was used to yield percent identification scores. Normal-hearing listeners showed sharp phoneme boundaries and strong reliance on the auditory cue, whereas actual and simulated implant listeners showed much weaker categorical perception but stronger dependence on the visual cue. The implant users were able to integrate both congruent and incongruent acoustic and optical cues to derive relatively weak but significant auditory-visual integration. This auditory-visual integration was correlated with the duration of the implant experience but not the duration of deafness. Compared with the actual implant performance, acoustic simulations of the cochlear implant could predict the auditory-only performance but not the auditory-visual integration. These results suggest that both altered sensory experience and improvised acoustic cues contribute to the auditory-visual speech perception in cochlear-implant users.     

Versatility of heterocyclic thioamides in the construction of a trinuclear cluster [Cu3I3(dppe)3 (SC5H4NH)] and Cu(I) linear polymers {Cu6(SC5H4NH)6I6}n x 2nCH3CN and {Cu(I)6 (SC3H6N2)6X6}n (X = Br, I)

Reaction of copper(I) iodide with pyridine-2-thione (2-SC5H4NH) and 1,2-bis(diphenylphosphino)ethane (dppe) in a CH3CN-CHCl3 mixture yielded a triangular cluster, [Cu3I3(mu2-P,P-dppe)3 (eta1-SC5H4NH)], 1. Similar reaction with 2-SC5H4NH and a series of diphosphanes, Ph2P-X-Ph2P {X = -CH2- (dppm), -(CH2)3- (dppp), -(CH2)4- (dppb), -CH=CH- (dppen)}, gave a novel iodo-bridged hexanuclear Cu(I) linear polymer,{Cu6(mu3-SC5H4NH)4 (mu2-SC5H4NH)2 (I4)(mu-I)2-}n x 2nCH3CN, 2. Reactions of copper(I) iodide/copper(I) bromide with 1,3-imidazolidine-2-thione (SC3H6N2) in a CH3CN-CHCl3 mixture yielded hexanuclear Cu(I) linear chain polymers, [{Cu6(mu3-SC3H6N2)2 (mu2-SC3H6N2)4X2 (mu-X)4}n] (X = Br, 4; I, 5). In compound 1, two iodide atoms and one dppe form the dinuclear Cu(mu2-I)2 (mu2-dppe)Cu core, and two dppe ligands bridge this core with the third Cu(I) center coordinated to 2-SC5H4NH via the S atom. The chain polymer 2 has a centrosymmetric hexanuclear central core, Cu6S6I4 (mu-I)2--, formed by dimerization of six-membered trinuclear motifs, Cu3(mu2-SC3H6N2)3I3 via (mu3-S) bonding modes of the thione ligand, and has four terminal and two bridging iodine atoms in trans-orientations. Linear chains are separated by the nonbonded acetonitrile molecules. In 4 and 5, three copper(I) bromide or copper(I) iodide moieties and three SC3H6N2 ligands combined via bridging S donor atoms to form the six-membered trinuclear Cu3(mu2-SC3H6N2)3I3 cores which polymerized via S and X atoms in a side-on fashion to form linear chain polymers, [{Cu6(mu3-SC3H6N2)2 (mu2-SC3H6N2)4X2(mu-X)4}n]. The (mu3-S) modes of bonding of neutral heterocyclic thioamides are first examples, as are trinuclear cluster and linear polymers rare examples in copper chemistry.