Abstract: Any sequence can be transformed into an equivalent one by alphabet change and/or encoding. Thus an information cannot be identified to a single sequence, but should be defined as the equivalence class among sequences with respect to such transformations, an abstract entity. It may be represented by its ‘information message’ defined as the shortest binary sequence in this class, whose length quantitatively measures the information. Any sequence must be borne by a physical medium, so information bridges the abstract and the concrete. Perturbations in the physical world result in random symbol errors, while information may instruct the assembly of physical objects by the agency of the semantics it bears. Information theory tells that errorless communication is possible provided a long and redundant enough error-correcting code is used. Conserving genetic information over the ages needs error-correcting codes making the exact regeneration of genomes possible provided it is performed frequently enough. In engineering, such codes are conveniently defined by mathematical constraints which make the symbols mutually dependent, but constraints of any kind, defining ‘soft codes’, also do the job. The better conservation of old parts of the genome implies moreover that the genomic error-correcting codes are made of nested component codes. This scheme accounts for basic life features: need for successive generations, existence of discrete species with hierarchical taxonomy, trend of evolution towards increased complexity, etc. Transcription of the genes and their translation into polypeptidic chains, becoming proteins when properly folded, are controlled by enzymes, which as proteins are needed for their own synthesis. A feedback loop results, referred to as ‘semantic’ since it implements the genetic code which tells the meaning of the genes. Once closed, it keeps its structure, thereby conserving the genetic code. The onset of a new semantic feedback loop originates an organic code in Barbieri’s meaning, which itself induces a new soft component in the system of genomic nested error-correcting codes by imposing new constraints to the genome. Due to the feedback, constraints incurred by the proteins affect the genome. Besides the synthesis of proteins, the assembly of living structures, as instructed by the genome, involves interwoven semantic feedback loops. Although closed, they do not prevent the genome lengthening, say by horizontal genetic transfer, which increases both the information quantity, hence its semantic specificity, and the redundancy, hence its error-correction ability. Thus, closing semantic feedback loops does not prevent evolution: new structures can be appended with improved resilience to errors. Regeneration failure is very infrequent and results in a widely different genome which originates a new species if the phenotype it specifies withstands the Darwinian selection. A possible scenario for the origin of semantic feedback loops (hence maybe of life) is proposed.
Pages: 173 – 190 | Full PDF Paper
Nguyen Thi Thu Ha, Vo Thi Anh, Ha Lan Anh, Vuong Thu Bac
Abstract: Environmental radiation monitoring around nuclear power plants is a mandatory task, an indispensable content of any nuclear power plants yet. The radiation measurement techniques using for environmental radioactivity monitoring are continuously being improved. One of the radioisotopes that should be regularly monitored is tritium (H-3), especially in the atmosphere. Tritium presents in the atmosphere mainly in the vapor (HTO) and gaseous (HT) forms. In this study the HTO and HT in the Hanoi atmosphere are collected simultaneously by the MARC-7000 Tritium sampler. The sampler was specifically designed for capturing Tritium by using a series of four bubbling bottles, a cooling system and an oven packed with Palladium-Alumina catalyst to oxydize HT. Sampling was carried out a flow rate of 30 L/h continuously for 10 to 14 days which depends on the atmosphere humidity. The trapping yields of HTO and HT were higher than 99% and 96%, respectively. The collected atmospheric moisture samples have been enriched by electrolysis then were measured for tritium activity on a Liquid Scintillation Analyzer Tri-carb 3170 TR/SL. Counting time was 100min x 10 cycles to achieve an accounting precision of less than 10%. The detection limit of the procedure was estimated as low as 0.46 TU. Average tritium radioactivity in the Hanoi atmosphere was found to be 16.94 (mBq/m3).
Keywords: HTO and HT in the atmosphere, MARC-7000 Tritium sampler, TRI CARB 3170 TR/SL LSA.
Pages: 191 – 199 | Full PDF Paper
Biological Activities of Endophytic Xylaria sp. Isolated from Tropical forest in Chaiyapoom Province, Thailand
Krittapong Orachaipunlap, Nuttika Suwannasai, Anthony J.S. Whalley, Cherdchai Phosri4, Prakitsin Sihanonth
Abstract: The ultimate goal in this study is to screen biological activities from endophytic Xylaria sp. isolated from leaf of 4 Dipterocarp forest tree species such as Cinnamomum iners, Shorea siamensis, Fermandoa adenophylla, Quercus semiserrata. All endophytic fungi isolates were obtained and identified based on morphological characteristics. Sixty-four from 125 endophyte isolates were belong to Xylaria genera. Moreover, the typical endophytic fungi genera such as Phomopsis spp., Pestalotiopsis sp., Colletotrichum sp., Phyllosticta sp., Daldinia sp., Aspergillus sp., Mycelia sterilia spp., were commonly found in tropical forest. Xylaria isolate sp.1 was the only one isolate that showed excellent broad spectrum antimicrobial against Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Candida albicans. Moreover, Xylaria isolate sp.9 showed strong inhibitory activity against all test bacteria. Moreover, Xylaria sp.1 showed the best efficiency of cytotoxicity against Jurkat cell line with IC50 value of 2.63 μg/mL and Xylaria sp.2 showed best efficiency of cytotoxicity against HEK293 cell line with IC50 value of 2.94 μg/mL..
Keywords: Endophytic fungi, Xylaria sp., Antimicrobial activity, Anticancer activity, Bioactive compound.
Pages: 200 – 208 | Full PDF Paper
Milene Aparecida Rodrigues de Oliveira (PQ), Keylla Utherdyany Bicalho (PG), Joao Batista Fernandes (PQ)
Abstract: Four flavonoids were theoretically studied trough B3LYP/6-311 ++G** method in order to evaluate the effect of flavonoid structural features on its stability and its ring planarity, applying the dihedral calculation. In this study were evaluated structures with a methyl group at positions 3 and 7 and the presence or not of the glucosyl group. The dihedral angle between AB to C rigns, Huckel charges and intramolecular hydrogen bonds were assigned.
Keywords: flavonoids, DFT, stability.
Pages: 209 – 214 | Full PDF Paper