1,824 research outputs found

    Protein enrichment of Irish potatoes by fermentation process using mutant isolates of Latobacillus bulgaricus

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    The study undertook the mutational selection of lactic acid bacteria used for the fermentation of peeled Solanum tuberosum (Irish Potatoes, Subtrate) in order to isolate mutants that may produce fermented Irishpotatoes product with improved nutritional quality (i.e increase protein content). Lactic acid bacteria were isolated from local yoghurt (“kindirmo” in hausa language) that were morphologically and culturally characterised and found to be predominantly Lactobacillus bulgaricus. Four (4) mutants selected randomly from Lactobacillus bulgaricus subjected to UV-light irradiation at 20 secs , 25 secs, 30 secs and 35 secs periods of exposure. The mutants exhibited similar morphological and cultural characteristics as the wild type strain. Fermentation of peeled Irish potatoes with wild type Lactobacillus bulgaricus gave no significant increase (P>0.05) in crude protein content from 7.37±0.42 g/100 g on the zero day to 8.73±0.43 g/100 g on the 5th day of fermentation, whereas, the mutant isolates gave a significant increase (

    Threshold photoelectron photoion coincidence spectroscopy of trichloroethene and tetrachloroethene

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    The threshold photoelectron, the threshold photoelectron photoion coincidence and ion breakdown spectra of trichloroethene and tetrachloroethene have been recorded from 9 – 22 eV. Comparisons with the equivalent data for the three dichloroethene molecules and theoretical calculations highlight the nature of the orbitals involved during photoionisation in this energy range. The ground electronic state of C2_2HCl3+_3^+ (C2_2Cl4+_4^+) is bound, with excited valence states dissociating to C2_2HCl2+_2^+ (C2_2Cl3+_3^+) and C2_2HCl+^+ (C2_2Cl2+_2^+). Appearance energies suggest that C2_2HCl+^+ forms from C2_2HCl3+_3^+ by loss of two chlorine atoms, whereas C2_2Cl2+_2^+ forms from C2_2Cl4+_4^+ by loss of a Cl2_2 molecule. The translational kinetic energy release into C2_2HCl2+_2^+ (C2_2Cl3+_3^+) + Cl is determined as a function of energy. In both cases, the fraction of the available energy released into translational energy of the two products decreases as the photon energy increases

    The photoionization dynamics of the three structural isomers of dichloroethene

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    Using tunable vacuum-UV radiation from a synchrotron, the threshold photoelectron spectrum, threshold photoelectron photoion coincidence spectrum and ion breakdown diagram of the 1,1, cis-1,2 and trans-1,2 isomers of C2_2H2_2Cl2_2 have been recorded in the range 9-23 eV. The energies of the peaks in the threshold photoelectron spectrum are in good agreement with outer-valence Greens function caculations. The major difference between the isomers, both predicted and observed experimentally is that the F and G states of C2_2H2_2Cl2+_2^+ are approximately degenerate for 1,1 and trans-1,2, but well separated for the cis-1,2 isomer. The ground and low-lying valence states of C2_2H2_2Cl2+_2^+ are bound, with higher-lying states dissociating to C2_2H2_2Cl+^+ or C2_2H2+_2^+. The translational kinetic energy release into C2_2H2_2Cl+^+ + Cl is determined as a function of energy. Isolated-state behaviour for the low-lying electronic states of C2_2H2_2Cl2+_2^+ becomes more statistical as the energy increases

    Production of 3,4-dihydroxy L-phenylalanine by a newly isolated Aspergillus niger and parameter significance analysis by Plackett-Burman design

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    <p>Abstract</p> <p>Background</p> <p>The amino acid derivative 3,4-dihydroxy L-phenylalanine (L-dopa) is gaining interest as a drug of choice for Parkinson's disease. <it>Aspergillus oryzae </it>is commonly used for L-dopa production; however, a slower growth rate and relatively lower tyrosinase activity of mycelia have led to an increasing interest in exploiting alternative fungal cultures. In the present investigation, we report on the microbiological transformation of L-tyrosine to L-dopa accomplished by a newly isolated filamentous fungus <it>Aspergillus niger</it>.</p> <p>Results</p> <p>The culture <it>A. niger </it>(isolate GCBT-8) was propagated in 500 ml Erlenmeyer flasks and the pre-grown mycelia (48 h old) were used in the reaction mixture as a source of enzyme tyrosinase. Grinded mycelia gave 1.26 fold higher L-dopa production compared to the intact at 6% glucose (pH 5.5). The rate of L-tyrosine consumption was improved from 0.198 to 0.281 mg/ml. Among the various nitrogen sources, 1.5% peptone, 1% yeast extract and 0.2% ammonium chloride were optimized. The maximal L-dopa was produced (0.365 mg/ml) at 0.3% potassium dihydrogen phosphate with L-tyrosine consumption of 0.403 mg/ml.</p> <p>Conclusion</p> <p>Over ~73% yield was achieved (degree of freedom 3) when the process parameters were identified using 2k-Plackett-Burman experimental design. The results are highly significant (p ≤ 0.05) and mark the commercial utility (LSD 0.016) of the mould culture which is perhaps the first ever report on L-dopa production from <it>A. niger</it>.</p

    A Robust Peak-to-Average Power Ratio Reduction Scheme by Inserting Dummy Signals with Enhanced Partial Transmit Sequence in OFDM Systems.

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    Peak-to-average power ratio (PAPR) is one of the main drawbacks in orthogonal frequency division multiplexing (OFDM) systems. High PAPR forces the power amplifier to back off in order to operate in its linear region, which degrades the power efficiency of the system. Several PAPR reduction techniques have been developed, but most of them have not considered both complexity and PAPR reduction. In this paper, a novel PAPR reduction scheme based on the insertion of dummy sequences to an enhanced partial transmit sequence is proposed. By applying this scheme the PAPR performance is enhanced compared to the conventional methods while the complexity is significantly reduced. Numerical analysis is carried out with OFDM signal and QPSK modulation

    Valorizing the 'Irulas' traditional knowledge of medicinal plants in the Kodiakkarai Reserve Forest, India

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    A mounting body of critical research is raising the credibility of Traditional Knowledge (TK) in scientific studies. These studies have gained credibility because their claims are supported by methods that are repeatable and provide data for quantitative analyses that can be used to assess confidence in the results. The theoretical importance of our study is to test consensus (reliability/replicable) of TK within one ancient culture; the Irulas of the Kodiakkarai Reserve Forest (KRF), India. We calculated relative frequency (RF) and consensus factor (Fic) of TK from 120 Irulas informants knowledgeable of medicinal plants. Our research indicates a high consensus of the Irulas TK concerning medicinal plants. The Irulas revealed a diversity of plants that have medicinal and nutritional utility in their culture and specific ethnotaxa used to treat a variety of illnesses and promote general good health in their communities. Throughout history aboriginal people have been the custodians of bio-diversity and have sustained healthy life-styles in an environmentally sustainable manner. However this knowledge has not been transferred to modern society. We suggest this may be due to the asymmetry between scientific and TK, which demands a new approach that considers the assemblage of TK and scientific knowledge. A greater understanding of TK is beginning to emerge based on our research with both the Irulas and Malasars; they believe that a healthy lifestyle is founded on a healthy environment. These aboriginal groups chose to share this knowledge with society-at-large in order to promote a global lifestyle of health and environmental sustainability
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