Synthesis and Crystal Structure of [Ni(H<Subscript>2</Subscript>O)<Subscript>2</Subscript>(pdc)(4-CNpy)] · 2H<Subscript>2</Subscript>O (pdc = Pyridine-2,6-dicarboxylate, 4-CNpy = 4-cyanopyridine)

Abstract A new complex containing two different substituted pyridine ligands, viz. 4-CNpy (4-cyanopyridine) and pdc (pyridine-2,6-dicarboxylate), [Ni(H₂O)₂(pdc)(4-CNpy)] · 2H₂O (1), has been prepared using [Ni(4-CNpy)₂(H₂O)₃(SO₄)] · H₂O (2) as the starting compound. Crystal data on 1 are: monoclinic, P2₁/c, a = 11.533(2) ?, b = 20.114(4) ?, c = 7.306(1) ?, β = 93.777(3)°, V = 1,691.1(5) ?³, Z = 2, D _calc. = 1.57 g cm⁻³, R ₁ = 0.0585, w R ₂ = 0.1236 for reflections with I > 4σ(F ₀) and 268 parameters (R ₁ = 0.0859, wR ₂ = 0.1336 for all 4,024 reflections). The discrete molecules of the title complex remain hydrogen-bonded to assemble into supramolecular layers interleaved by disordered water molecules. In an attempt to obtain the cationic complex species cis-[Ni(H₂O)₄(4-CNpy)₂]²⁺ we have isolated the compound [Ni(H₂O)₄(4-CNpy)₂] · (BPh₄)₂ · 2(4-CNpy) · 4H₂O (3) by adding NaBPh₄ to an aqueous solution of 2. Crystal data on 3 are: monoclinic, P2₁/n, a = 10.5002(1) ?, b = 21.1692(3) ?, c = 15.3249(2) ?, β = 95.120(1)°, V = 3392.84(7) ?³, Z = 2, D _calc. = 1.231 g cm⁻³, R ₁ = 0.0453, wR ₂ = 0.1217 for reflections with I > 4σ (F ₀) and 556 parameters (R ₁ = 0.0688, wR ₂ = 0.1364 for all 9,257 reflections). Index Abstract Synthesis and Crystal Structure of [Ni(H₂O)₂(pdc)(4-CNpy)] · 2H₂O (pdc = Pyridine-2,6-dicarboxylate, 4-CNpy = 4-cyanopyridine) Manjit K. Bhattacharyya, Sanchay J. Bora and Birinchi K. Das Crystal structure of a new nickel(II) complex displaying a supramolecular layered structure is described. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Reduction in timing jitter by chirp selection for externally modulated return to zero optical soliton pulse at 10 Gb/s

We investigate the chirp selection of externally modulated RZ soliton pulse at 10 Gb/s for fiber optical communication systems for the reduction in timing jitter. We have chosen single arm Mach-Zehnder amplitude modulator with sin² electrical shaped input-output (P-V) characteristic and its chirp range has been varied in the range of −5 to 5. The timing jitter, Q factor and bit error rate (BER) generated for the chirp range has been studied for various fiber lengths and post compensation has been demonstrated to reduce the timing jitter. The number of fixed output amplifiers after every 60 km span is varied from 2 to 10 and corresponding accumulated ASE noise has been studied to manage timing jitter and BER in permissible range, i.e. 5 ps and 10⁻⁹, respectively. It is observed that when two fiber spans are taken then the compensating fiber length for the system is less than 20 km for each case of the chirp considered. For 10 fiber spans, the compensating fiber length increases in the range 60-90 km depending upon the value of chirp taken. Finally it is shown that the chirp value of external modulator should be set to either 0 or −1 for externally modulated RZ soliton pulse in 10 Gb/s optical communication system which makes the system more insensitive to the timing jitter and the selection of dispersion compensating fiber length.     

A fast and simple Steiner routing heuristic

This paper presents a simple yet efficient heuristic for rectilinear Steiner routing. The basic heuristic introduces a new edge into the existing tree for another, costlier edge such that the resulting graph remains a tree. The simplicity of the heuristic led to an O(n²) implementation using basic data structures. Asymptotic time requirement of the heuristic can be further improved to O(n log n) using sophisticated data structures. Due to the generality of the heuristic different cost criteria can be applied to produce routes with different properties. The heuristic has been successfully applied to the problem of minimum-length Steiner routing and minimizing critical-sink Elmore delay.     

Effect of Gd3+ doping on structural,optical and frequency-dependent dielectric response properties of pseudo-cubic BaTiO3 nanostructures

We report on the structural, optical and dielectric characterization of solid state derived, pseudo-cubic nanoscale barium titanates (BTs) with gadolinium (Gd³⁺) as substitutional dopant. Referring to X-ray diffractograms, apart from the BT peaks related to perovskite structure, the non-existence of any additional peaks due to byproducts has revealed that Gd³⁺ has undergone substitutional doping into the BT host lattice. The well-separated BT nanoparticles of typical size ～10–15 nm were observed through electron microscopy studies. Following a direct, allowed type carrier transition (n=1/2), a reduction in the optical band gap value (from 3.28 to 3.255 eV) was observed when the Gd-doping level was varied within 0–7 %. Conversely, the Urbach energy followed an increasing trend, from a value of 0.741 to 1.879 eV. Furthermore, the dielectric constant showed a decreasing tendency with doping content and with increasing frequency. However, in the low-frequency region, the loss tangent (tanδ), which is the combined result of orientational polarization and electrical conduction, was found to be quite high in the doped samples as compared to their un-doped counterpart. The frequency-dependent electrical data were also analyzed in the framework of conductivity and impedance formalisms. In particular, the ac conductivity which varies as ～ω ^s approaches ideal Debye behavior (s→1) for a low Gd level and a higher doping concentration did not show improved dielectric feature of the host. The incorporation of rare-earth (Gd³⁺) ions into the BT host system could greatly manifest dielectric relaxation and carrier conduction mechanisms, in a given frequency range, and thus can find immense scope in miniaturized nanoelectronic elements including ceramic capacitors and transducers.     

Neutral charm production in 400 GeV proton-emulsion interactions

A search has been carried out for neutral charm production in 5,108 proton-emulsion interactions at 400 GeV/c. Nine charm candidates have been observed in our fiducial volume which extends from 100 μm-1,000 μm in the forward cone. One of these is a 4-prong and the others are 2-prong events with opening angle>10 mrad and momenta of both decay tracks>150 MeV/c. Search for associated charm decays was made in an extended fiducial volume around the primary stars of these nine candidates. This yielded two neutral 2-prong events, one associated with the 4-prong and the other with a 2-prong candidate. All unassociated candidates are consistent with being backgrounds due toK _s , Λ decays, neutral interactions and γ conversions whereas the background to associated events is negligible. Based on the two associated decays the inclusive cross section forD ^{0, ?0} production is determined as 27±20 μb/nucleon. Detailed measurements on the 4-prong candidate lead to the identification of one decay track as an electron and another as a kaon. This is interpreted as a semi-leptonic, Cabbibo favouredD ⁰/D ^?0 decay.     

Determining the molar mass of a plasma substitute succinylated gelatin by size exclusion chromatography-multi-angle laser light scattering,sedimentation equilibrium and conventional size exclusion chromatography

The clinical effectiveness of succinylated gelatin as a plasma substitute depends strongly on its molar mass, determined conventionally by size exclusion chromatography (SEC). This study evaluates different SEC calibration standards in comparison with two independent "absolute" methods for determining the weight average molar mass (M(w)) of a succinylated gelatin sample. SEC calibrated using succinylated gelatin fractions correlated well with size exclusion chromatography-multi-angle laser light scattering (SEC-MALLS) and sedimentation equilibrium whereas SEC calibrated with unmodified gelatin, sodium polystyrene sulfonates or pullulans overestimated M(w) by over 20%. Universal calibration was equivocal. The problems associated with the preparation of succinylated gelatin fractions suggest that an absolute method such as SEC-MALLS may be a more suitable choice for determining the M(w) in succinylated gelatins.     

Timing jitter dependence on data format for ideal dispersion compensated 10 Gbps optical communication systems

Simulations for data formats Return to Zero (RZ), Non-Return to Zero (NRZ), RZ-Soliton, Duobinary and their subcategories have been done with and without ideal dispersion compensation for optical communication systems. The results show that, in general, dispersion compensation improves timing jitter. RZ-Rectangular pulses show the smallest value of jitter without compensation. It has been observed that the RZ-Raised Cosine, and Soliton, give minimum jitter after ideal compensation. It has been reported that the BER performance of optical communication system using Duobinary data format is 10⁻⁸ and 10⁻³⁷ before and after dispersion compensation, respectively. Further the comparative study shows that the timing jitter is the lowest in case of RZ-Soliton (0.0127 ns) after dispersion compensation and 0.0135 ns for RZ-Rectangular data format before dispersion compensation.     

An effective numerical method for gain profile optimizations of multi pumped fiber Raman amplifiers

In this paper, we have solved propagation equations of multi-pump fiber Raman amplifier using Runge–Kutta (RK 4th order) numerical method and pump power evolutions along with the fiber length. They are used to calculate the net gain and gain ripple by varying the input signals powers for different fiber lengths. The pump powers are optimized by genetic algorithm and resulting net gain and gain ripple are reported graphically as well as in tabular form. The optimum minimum gain ripple is 0.26 dB for 1 mW input signal powers for 50 km fiber length. By increasing the fiber length gain ripple increases to 0.5 dB for 0.1 mW input signal power. In comparison to other methods reported in the literature, our method is simple to implement and efficient for numerical design of Raman amplification in optical communication systems.     

Analysis of Differentially Expressed Proteins in Colorectal Cancer Using Hydroxyapatite Column and SDS-PAGE

Limitation on two dimensional (2D) gel electrophoresis technique causes some proteins to be under presented, especially the extreme acidic, basic, or membrane proteins. To overcome the limitation of 2D electrophoresis, an analysis method was developed for identification of differentially expressed proteins in normal and cancerous colonic tissues using self-pack hydroxyapatite (HA) column. Normal and cancerous colon tissues were homogenized and proteins were extracted using sodium phosphate buffer at pH 6.8. Protein concentration was determined and the proteins were loaded unto the HA column. HA column reduced the complexity of proteins mixture by fractionating the proteins according to their ionic strength. Further protein separation was accomplished by a simple and cost effective sodium dodecyl sulfate-polyacrylamide gel electrophoresis method. The protein bands were subjected to in-gel digestion and protein analysis was performed using electrospray ionization (ESI) ion trap mass spectrometer. There were 17 upregulated proteins and seven downregulated proteins detected with significant differential expression. Some of these proteins were low abundant proteins or proteins with extreme pH that were usually under presented in 2D gel analysis. We have identified brain mitochondrial carrier protein 1, T-cell surface glycoprotein CD1a, SOSS complex subunit B2, and Protein Jade 1 which were previously not detected in 2D gel analysis method.