1,720,980 research outputs found
Purification of and factors affecting 5'-phosphodiesterase from germinating adzuki (Vigna angularis L.) bean
Full text link5’-Phosphodiesterase (5’-PDE) is an enzyme that hydrolyses RNA to form 5’-inosine monophosphate (5’-IMP) and 5’-guanosine monophosphate (5’-GMP) which function as
flavour enhancers. The best producer of 5’-PDE was selected from germinated seeds, namely mung bean (Vigna radiate), soybean (Glycine max), adzuki bean (Vigna angularis L.), chick pea (Cicer arietinum), black eye pea (Vigna unguiculata) and petai (Parkia speciosa). In order to ensure there is no contamination during germination, the
effects of different surface sterilizing treatments were examined. Sodium hypochlorite at 0.3% (v/v) concentration was able to inhibit mold growth in adzuki bean, soybean and
chickpea. Only 0.1% (v/v) sodium hypochlorite was needed to inhibit mold growth in black eye pea and petai, while mung bean required 0.05% (v/v) sodium hypochlorite to
inhibit mold growth. 5’-PDE activity was determined using thymidine 5’-monophosphate p-nitrophenyl ester as substrate at pH 7.0 and 55°C. The formation of nucleotide monophosphates, the products of reaction, was determined at 405 nm. As a strong presence of phosphomonoesterase (PME) will reduce the yield of nucleotide monophosphates as the enzyme hydrolyzes these products into nucleosides and
orthophosphate, PME activity was also determined using p-nitrophenyl phosphate as the substrate at 60°C and pH 5.0. Adzuki bean was found to have the highest 5’-PDE
activity when germinated for 15 days.
5’-PDE has an optimum pH and temperature of 8.5 and 80°C, respectively. It was stable between pH 7.0 - 8.5. A higher stability was observed at pH 7.5 compared to pH 8.5, and
at 60 and 65°C, the enzyme still possessed good catalytic function even after 4 days of incubation. EDTA, Triton X-100 and sodium dodecyl sulfate (SDS) strongly inhibited
5’-PDE activity (inhibition ranged from 75.2-99.4 %), while Tween 80 and Tween 20 were only slightly inhibitory. The enzyme was activated by Ca2+ up to 249%, K+, Mg2+
and Li+, when the final concentration of the cations was 10 mM. On the other hand, Na+,Zn2+, Ni+, Hg+, Cu2+, Pb2+, Fe2+, Al3+, Ba2+ and Co2+ at the same final concentration were inhibitory. 5’-PDE activity increased with an increase in the concentration of Li+, Na+ and Mg2+, until it reaches its maximum at 6 mM followed by a decrease in activity at
concentrations beyond 6 mM. The presence of Ca2+ in the reaction mixture resulted in a similar trend, but the difference is that maximum activation occurred at 4 mM. K+,
however, increased the activity of 5’-PDE from 0-10 mM. Al3+ decreased the activity of 5’-PDE activity as the concentration of the cation was increased. Thus, it is suggested that 5’-PDE from adzuki bean is a metallo-enzyme.
The yield of 5’-PDE after the four purification steps (acetone precipitation, desalting,anion-exchange chromatography and gel filtration chromatography) was 13.37% with a purification fold of 6.7 and specific enzyme activity of 35.2 μmol p-nitrophenol/min/mg protein. The molecular weight of 5’-PDE using gel filtration chromatography was estimated at 125 kDa. Native PAGE analysis showed one major protein band, while SDS-PAGE estimated the molecular weight of the enzyme to be 124 kDa and indicated that the active/intact enzyme may be composed of two identical polypeptide chains (subunits) with a molecular weight of 62 kDa each. In conclusion, although 5’-PDE from adzuki bean has a high temperature optimum of 80 oC, the enzyme is more stable at 60oC, different cations affected the activity of the enzyme differently and the purified 5’-PDE has an estimated molecular weight of 124-125 kDa
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Effects of germination conditions on 5’-phosphodiesterase activity of selected seeds
Full text link5'-Phosphodiesterase (5'-PDE) is an enzyme that hydrolyses RNA to form 5'-inosine monophosphate (5'-IMP) and 5'-guanosine monophosphate (5'-GMP), which function as flavour enhancers. Selection of the best producer of 5'-PDE was made by determining the activity of the enzyme in six seeds that have been germinated, namely mung bean (Vigna radiate), soybean (Glycine max), adzuki/red bean (Vigna angularis L.), chick pea (Cicer arietinum), black eye pea (Vigna unguiculata) and petai (Parkia speciosa). Seeds that were not germinated acted as the control. In order to ensure there is no contamination from potential 5'-PDE-producing microorganisms during germination, microbial growth was reduced by using different surface sterilizing treatments where the seeds were soaked in 100 mL solution containing different concentrations of sodium hypochlorite (with or without 0.05% sodium azide) for 5 minutes before rinsing it five times with sterilized distilled water (total 500 mL).The seeds were observed every day for 3 days and the best surface sterilizing treatment was selected based on absence of mold growth and the effects on hypocotyl length. Sodium hypochlorite at 0.3% (v/v) concentration was able to inhibit mold growth in adzuki bean, soybean and chickpea. On the other hand, only 0.1% (v/v) sodium hypochlorite was needed to inhibit mold growth in black eye pea and petai, while mung bean required 0.05% (v/v) sodium hypochlorite to inhibit mold growth. Under these conditions, the growth of hypocotyl (hypocotyls length) was only slightly affected compared to the control. 5'-PDE was extracted from seeds that have been germinated for 24 hours and their control (ungerminated seeds) by homogenization in a blender with 400 mL of 50 mM acetate buffer, pH 4.5. After that, the homogenates were stirred for 30 min and the centrifuged at 9000 rpm for 15 min at 10°C. 5'-PDE activity was determined using thymidine 5'-monophosphate p-nitrophenyl ester as substrate at pH 7.0 and 55°C. The formation of nucleotide monophosphates, the products of reaction, was determined at 405 nm. As a strong presence of phosphomonoesterase (PME) will reduce the yield of nucleotide monophosphates as the enzyme hydrolyzes these products into nucleosides and orthophosphate, PME activity was also determined using p-nitrophenyl phosphate as the substrate at 60°C and pH 5.0. Thus, the seed with the highest 5'-PDE activity and a low PME activity can be selected. Germinated adzuki bean was found to have the highest 5'-PDE activity (0.59 μmol p-nitrophenol/min/mg protein) among the germinated seeds. A time-course study indicated that the level of 5'-PDE in adzuki bean increased with time of germination until 15 hours (0.69 μmol p-nitrophenol/min/mg protein), after which the acitivity decreased until it reached the basal level (0.44 μmol p-nitrophenol/min/mg protein) at 72 hours. On the other hand, PME in the bean was the highest at 9 h germination(0.98 μmol p-nitrophenol/min/mg protein). In general, controls have very low basal level of 5'-PDE activity (0.18-0.42 μmol p-nitrophenol/min/mg protein)
Chitosan film incorporated with Garcinia atroviridis for the packaging of Indian mackerel (Rastrelliger kanagurta)
No full textABSTRACT Herbs and spices, having antimicrobial effect, can be incorporated into edible films, to extend product shelf life and the reduce the risk of microbial growth on food. The aim of this study is to develop chitosan film incorporated with Garcinia atroviridis, also known as ‘asam gelugur’, ‘asam gelugo’, or ‘asam keping’. The film with different concentrations of Garcinia atroviridis (1 to 5% v/v) with chitosan (1.5% w/v) were investigated for its physical, mechanical and antibacterial properties. With the increase of Garcinia atroviridis extract incorporated, water solubility of the films increases (from 21.17 to 53.61%). Increase of Garcinia atroviridis incorporated into chitosan film also increase the total color difference. Film with higher concentration of Garcinia atroviridis extract produced thicker film compared to the film without extract (from 0.048 to 0.143 mm). The film with 5% (v/v) Garcinia atroviridis possessed low tensile strength (3.28 MPa) and elongation at break (13.90%). Young’s modulus was decreased in value (from 0.72 to 0.24 MPa) as the higher concentration of Garcinia atroviridis extract was added. High Garcinia atroviridis extract (5% v/v) in the chitosan films demonstrated greater inhibitory activity against the bacteria strains (Pseudomonas aeruginosa, Bacillus subtilis and Staphylococcus aureus). With the edible film of 5% (v/v) Garcinia atroviridis applied, the Indian mackerel was found to have a longer shelf life (3.5 days) as compared to the control (2.5 days)
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
- …
