Penalty-free 10 Gbit/s single-channel co-pumped distributed Ramanamplification using low RIN 14xx nm DFB pump

A penalty-free 10 Gbit/s single-channel transmission with co-pumped distributed Raman amplification using a novel high power, low relative integrity noise (RIN), multimode 14xx nm distributed feedback pump is reported. No penalty from pump to signal RIN transfer was observed with co-pumped Raman gains up to 6 dB large effective area fibre (LEAF). In contrast, 0.5 dB penalty was observed with a fibre Bragg grating stabilised pump at 6 dB of Raman gain     

A room temperature process for making Mn2O3 nano-particles and γ-MnOOH nano-rods

Nano-size crystals of Mn₂O₃ and MnOOH have been prepared by a simple precipitation process using dilute aqueous solutions of manganese sulphate and ammonia in the presence of sodium lauryl sulphate — a surface active agent. X-ray diffraction spectrometry has been used to identify the phases and to calculate the size of the nano-size crystals using the Scherrer method. The morphology of the crystals has been studied by TEM/HRTEM and Edax has been used to estimate their elemental constituents. The sonication of the prepared nano-size material in acetone leads to the conversion of MnOOH to nano-sized Mn₂O₃.     

A measurement-based approach for power system instability early warning

Early warning of impending instability in a power system under disturbance conditions is important for preventing of system collapse. A measurement-based approach is proposed to assess the potential power system transient instability problem under cascading outages. Where a measurement-based index is obtained as the estimation accuracy of a linear autoregressive exogenous (ARX) model to estimate the dynamic response of the power system and indicate the system stability to some extent after a disturbance. The proposed approach was verified using a set of marginally stable cases in a 179-bus WECC equivalent power system.     

Molecular evolution of a defined DNA sequence with accumulation of mutations in a single round by a dual approach to random chemical mutagenesis (DuARCheM)

Directed evolution has paved the way to a new era of protein and nucleic acid molecules with improved and enhanced properties. The utmost important component of directed evolution is random mutations in a defined DNA sequence. The utility of random chemical mutagenesis in directed evolution studies is dwindling due to the inherent flaws with whole-organism mutagenesis and the in vitro approach. Here, we report a novel Dual Approach to Random Chemical Mutagenesis (DuARCheM) to introduce random mutations in a defined DNA fragment. DuARCheM involves in vivo chemical mutagenesis and in vitro genetic manipulations. The resulting library revealed an accumulation of mutations in its members. These results imply that the parent mutation is carried in the further generations within the same library. This method might help to change random chemical mutagenesis because the combination of in vivo and in vitro approaches mimics the amplification and mutation that is performed by PCR-based mutagenesis, and at the same time the mutations are confined to the desired gene. Moreover, the mutagen pressure is greater in chemical mutagenesis than in a Taq-polymerase-based error-prone system. Concomitant amplification and mutation in the DuARCheM method leads to a better spectrum of mutants because the plasmid construct is exponentially amplified in the presence of mutagen pressure, unlike in the in vitro chemical mutagenesis system in which the template molecule does not replicate. This work is able to nullify all the disadvantages that are associated with random chemical mutagenesis, and could make random chemical mutagenesis an indispensable tool in directed evolution studies.     

Preparation and characterization of chemically synthesized poly(N-methylaniline)

Poly(N-methylaniline) (PNMA), a electrically conductive derivative of polyaniline was synthesized by chemical polymerization of N-methylaniline (NmANI) using ammoniumpersulfate (APS) as an oxidizing agent and studied by electrical conductivity measurement, UV–vis and FTIR spectroscopy. The observed electrical conductivity was found to have a dependence on some synthesis parameters. The oxidant/monomer molar ratio ∼1 and p-toluenesulfonic acid (PTSA)/monomer molar ratio ∼4 showed higher values of electrical conductivity for the polymer. The d.c. conductivities of PTSA doped poly(N-methylaniline) have been measured in the temperature range 298–373 K. The conductivity of the samples has been observed to show an increasing trend with increasing temperature. However, on increasing temperature from 298 K to 373 K, the conductivity rise was found to be more for the samples having lower dopant/monomer ratio. The observed d.c. conductivity data was described by Mott's three-dimensional variable range hopping (VRH) model.     

Rehabilitating acid soils for increasing crop productivity through low-cost liming material

Productivity of red and lateritic soils is low because of their acidity and deficiencies in few essential nutrients viz., nitrogen, phosphorus, calcium, zinc, boron, molybdenum etc. We compared the effectiveness of basic slag, a low-cost liming material, with that of calcite as an ameliorant for these soils using mustard followed by rice as test crops. Experiments were conducted with three levels of each of basic slag and calcite along with a control on farmers' fields at 14 different locations. Influence of farmyard manure (FYM) and poultry manure (PM) on the effectiveness of the slag was also tested. On an average, basic slag performed better than calcite in increasing yields of both mustard and rice and left over higher amounts of available Ca, Si and Zn in residual soils. The slag also improved N, P, K and Ca nutrition of mustard and Si and Zn nutrition of rice with a favorable benefit:cost (B:C) ratio over the calcite (4.82 vs. 1.44). Effectiveness of the basic slag improved when it was applied in combination with FYM or PM (B:C, 5.83 and 6.27). Basic slag can, therefore, be advocated for use in the acidic red and lateritic soils for economically improving their productivity.     

Role of Cenosphere Addition on Dielectric Properties of Sisal Fiber-Polypropylene Composites

This research investigates the influence of addition of porous additives on dielectric constant of polypropylene. Composite composed of PP matrix with sisal fiber having cylindrical pores and cenospheres having spherical pore, presents low dielectric constant. A new relation concerning porosity is proposed by modifying the usual mixing rule to predict the dielectric constant of PP composite. This research presents the dielectric properties of sisal fiber-reinforced PP composites with and with out cenospheres. Treated and untreated cenospheres with different concentration were loaded in chopped sisal fiber-reinforced polypropylene. The loading of the polypropylene with the sisal fiber, increases the dielectric constant ε′ and improves the ac conductivity σ_ac. The effect of temperature on the dielectric spectrum of polypropylene composites was investigated in the frequency range ranging from 1–10 kHz. Sisal fiber-reinforced polypropylene composites having 20% sisal fiber with and without cenospheres were developed and electrical properties such as dielectric constant (?′), dissipation factor (tanδ) and ac conductivity (σ_ac) of these composites were determined. Dielectric constant, tan δ, and a.c. conductivity increases with increase in temperature at different frequencies.     

STATISTICAL ANALYSIS OF REACTION RATE DATA OF LIQUID PHASE SYNTHESIS OF DIMETHYL ETHER FROM METHANOL

Abstract

The liquid phase catalytic dehydration of methanol to dimethyl ether (DME) is a key reaction step in the single-step synthesis of DME from CO-rich syngas in a slurry reactor. The effect of process variables including temperature, pressure, impeller speed, and feed methanol flow rate on DME synthesis rate has been studied by a systematic 24 full factorial experimental design with single replicate. The significant effects and interactions have been quantified by F-tests. The estimates of significant effects have been obtained by Yates' algorithm. Residual probability and normal probability dots have been obtained to test model adequacy. Finally, a computational model has been developed to predict the DME synthesis rate alt various values of process variables. The model has excellent interpolational predictive capability as evidenced by parity plots.     

THE APPLICATIONS OF A GENERALIZED EQUATION OF STATE TO THE CORRELATION AND PREDICTION OF PHASE EQUILIBRIA*

Two methods of generalizing an equation of state are demonstrated and their limitations are outlined. One method involves the correlation of the equation of state constants and the second method involves a recently proposed Generalized Corresponding States Principle based on the properties of two (nonspherical) reference fluids. The PVT properties of pure fluids are represented by a new cubic equation of slate with four parameters which are obtained from vapor pressure and saturated liquid density data. It is demonstrated how a limited amount of data on key components may be used to obtain phase equilibria in mixtures.     

Fate of Fertilizer15N applied as urea and ammonium sulphate in opium poppy (Papaver somniferum L.) grown under greenhouse conditions

Laboratory incubation and greenhouse experiments were conducted to investigate the comparative effectiveness of urea and ammonium sulphate in opium poppy (Papaver somniferum L.) using¹⁵N dilution techniques. Fertilizer treatments were control (no N), 600 mg N pot^–1 and 1200 mg N pot^–1 (12 kg oven dry soil) applied as aqueous solution of urea or ammonium sulphate. Fertilizer rates, under laboratory incubation study were similar to that under greenhouse conditions. A fertilizer¹⁵N balance sheet reveals that N recovery by plants was 28–39% with urea and 35–45% with ammonium sulphate. Total recovery of¹⁵N in soil-plant system was 77–82% in urea. The corresponding estimates for ammonium sulphate were 89–91%. Consequently the unaccounted fertilizer N was higher under urea (18–23%) as compared to that in ammonium sulphate (9–11%). The soil pH increased from 8.2 to 9.4 with urea whereas in ammonium sulphate treated soil pH decreased to 7.3 during 30 days after fertilizer application. The rate of NH₃ volatilization, measured under laboratory conditions, was higher with urea as compared to the same level of ammonium sulphate. The changes in pH of soil followed the identical trend both under laboratory and greenhouse conditions.