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1.
J Appl Microbiol ; 120(6): 1531-41, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-26929429

RESUMO

AIMS: The aims of this study were (i) to develop a protocol for the entrapment of anaerobic (hyper)thermophilic marine micro-organisms; (ii) to test the use of the chosen polymers in a range of physical and chemical conditions and (iii) to validate the method with batch cultures. METHODS AND RESULTS: The best conditions for immobilization were obtained at 80°C with gellan and xanthan gums. After 5-week incubation, beads showed a good resistance to all tested conditions except those simultaneously including high temperature (100°C), low NaCl (<0∙5 mol l(-1) ) and extreme pH (4/8). To confirm the method efficiency, batch cultures with immobilized Thermosipho sp. strain AT1272 and Thermococcus kodakarensis strain KOD1 showed an absence of detrimental effect on cell viability and a good growth within and outside the beads. CONCLUSION: This suggests that entrapment in a gellan-xanthan matrix could be employed for the culture of anaerobic (hyper)thermophilic marine micro-organisms. SIGNIFICANCE AND IMPACT OF THE STUDY: (Hyper)thermophilic marine micro-organisms possess a high biotechnological potential. Generally microbial cells are grown as free-cell cultures. The use of immobilized cells may offer several advantages such as protection against phage attack, high cell biomass and better production rate of desired metabolites.


Assuntos
Bactérias/crescimento & desenvolvimento , Técnicas Microbiológicas/métodos , Polissacarídeos Bacterianos , Thermococcus/crescimento & desenvolvimento , Bactérias/classificação , Técnicas de Cultura Celular por Lotes , Temperatura Alta , Água do Mar/microbiologia
2.
Chem Sci ; 7(2): 945-950, 2016 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-29896365

RESUMO

Graphitic carbon nitride (g-CN) has interesting catalytic properties but is difficult to study due to its structure and how it is produced. In this study, linear s-heptazine oligomers were synthesized to serve as well-defined molecular models for g-CN. Cyclic voltammetry, absorption and emission spectroscopies showed a clear shift of properties towards those of g-CN as the number of heptazine units increased. DFT calculations supported the characterizations, and helped refine the properties observed.

3.
Astrobiology ; 5(1): 48-65, 2005 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-15711169

RESUMO

The need for criteria to compare different analytical methods for measuring extraterrestrial organic matter at ultra-trace levels in relatively small and unique samples (e.g., fragments of meteorites, micrometeorites, planetary samples) is discussed. We emphasize the need to standardize the description of future analyses, and take the first step toward a proposed international laboratory network for performance testing.


Assuntos
Aminoácidos/análise , Meio Ambiente Extraterreno/química , Microquímica/métodos , Compostos Orgânicos/análise , Exobiologia , Meteoroides , Microquímica/estatística & dados numéricos , Origem da Vida , Sensibilidade e Especificidade
4.
Anal Chim Acta ; 721: 44-54, 2012 Apr 06.
Artigo em Inglês | MEDLINE | ID: mdl-22405299

RESUMO

Optimal fractions of resolution V design matrices proposed by Rechtschaffner in 1967 are developed and applied as supersaturated designs in screening experiments. Rechtschaffner matrices allow evaluation of all main factors and two-factor interactions, which in many real-world studies are of practical significance. However, the number of experimental runs increases rapidly with the number of factors in the matrices, which are therefore impractical for more than 5-6 factors. On the contrary, saturated fractions based on Hadamard matrices, which are commonly applied in screening studies, cannot evaluate the interaction effects. Here, a procedure for selecting the optimum fractions of Rechtschaffner matrices is presented and provides supersaturated matrices that are well adapted to a variety of problems, thus allowing the development of screening studies with a relatively small number of experiments. The procedures developed to derive the size-reduced matrices and to evaluate the active factors are discussed and compared in terms of efficiency and reliability, by means of simulation studies and application to a real problem. These fractions are the first supersaturated design matrices capable of estimating interaction effects. Additionally, one important advantage of these supersaturated matrices is that they enable development of follow-up procedures in cases of inconclusive results, by enlarging the matrix and eventually resolving the full Rechtschaffner matrix of departure when it is necessary to evaluate the active factors and their interactions.

5.
Int J Pharm ; 378(1-2): 23-9, 2009 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-19465095

RESUMO

Over the years, different formulation technologies intended for gastro retentive dosage delivery were investigated and patented. The aim of this study was to develop an innovative floating gastro retentive dosage form (GRDF). The developed technology induces a low-density dosage form containing high active pharmaceutical ingredient (API) concentration by using a hydrophobic dusty powder excipient under specific conditions. The new dosage form was obtained by state of the art wet granulation manufacturing process. An experimental design using a discrete variable and four mixture variables was conducted in order to optimize API concentration and buoyancy of the new dosage form. An apparatus was developed to measure the apparent density of floating tablet. The GRDF was characterized for apparent density, buoyancy, porosity and dissolution using in vitro experimentations.


Assuntos
Excipientes/química , Preparações Farmacêuticas/administração & dosagem , Tecnologia Farmacêutica/métodos , Administração Oral , Química Farmacêutica/métodos , Interações Hidrofóbicas e Hidrofílicas , Porosidade , Solubilidade , Comprimidos
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