scholarly journals Characterization of Exopolysaccharides Produced by Rhizobia Species

2015 ◽  
Vol 39 (6) ◽  
pp. 1566-1575 ◽  
Author(s):  
Tereza Cristina Luque Castellane ◽  
Alda Maria Machado Bueno Otoboni ◽  
Eliana Gertrudes de Macedo Lemos
Keyword(s):  
High Performance ◽  
Biological Properties ◽  
Reversed Phase ◽  
The Past ◽  
Structure And Dynamics ◽  
Key Factor ◽  
Reactive Groups ◽  
Potential Applications ◽  
Species Specific

ABSTRACT Increasing attention has been given, over the past decades, to the production of exopolysaccharides (EPS) from rhizobia, due to their various biotechnological applications. Overall characterization of biopolymers involves evaluation of their chemical, physical, and biological properties; this evaluation is a key factor in understanding their behavior in different environments, which enables researchers to foresee their potential applications. Our focus was to study the EPS produced by Mesorhizobium huakuii LMG14107, M. loti LMG6125, M. plurifarium LMG11892,Rhizobium giardini bv. giardiniH152T, R. mongolense LMG19141, andSinorhizobium (= Ensifer)kostiense LMG19227 in a RDM medium with glycerol as a carbon source. These biopolymers were isolated and characterized by reversed-phase high-performance liquid chromatography (RP-HPLC), Fourier transform infrared (FTIR), and nuclear magnetic resonance (NMR) spectroscopies. Maximum exopolysaccharide production was 3.10, 2.72, and 2.50 g L-1for the strains LMG6125, LMG19227, and LMG19141, respectively. The purified EPS revealed prominent functional reactive groups, such as hydroxyl and carboxylic, which correspond to a typical heteropolysaccharide. The EPS are composed primarily of galactose and glucose. Minor components found were rhamnose, glucuronic acid, and galacturonic acid. Indeed, from the results of techniques applied in this study, it can be noted that the EPS are species-specific heteropolysaccharide polymers composed of common sugars that are substituted by non-carbohydrate moieties. In addition, analysis of these results indicates that rhizobial EPS can be classified into five groups based on ester type, as determined from the 13C NMR spectra. Knowledge of the EPS composition now facilitates further investigations relating polysaccharide structure and dynamics to rheological properties.

Reaction Pathways to 2-Aminothiophenes and Thiophene-3-carbonitriles

2009 ◽  
Vol 62 (5) ◽  
pp. 402 ◽  
Author(s):  
Luigi Aurelio ◽  
Bernard L. Flynn ◽  
Peter J. Scammells
Keyword(s):  
Comparative Studies ◽  
Reaction Pathway ◽  
Reaction Pathways ◽  
Synthesis And Characterization ◽  
The Past ◽  
Adenosine A1 ◽  
Unexpected Reaction ◽  
Potential Applications ◽  
A1 Receptor

Over the past two decades 2-amino-3-benzoylthiophenes have been found to act as allosteric enhancers of the adenosine A1 receptor (A1AR). As such, compounds of this type have potential applications in the therapy of a variety of disorders by enhancing A1AR activation. Initial studies in this field identified various 2-amino-3-benzoylthiophenes as potential leads and of these PD 81723 1a has become the benchmark for comparative studies due to its favourable ratio of allosteric enhancement to antagonism. Surprisingly the synthesis and characterization of PD 81723 1a has not been previously reported. Herein we report the synthesis and characterization of this important A1AR allosteric enhancer. As part of this study we also found an unexpected reaction pathway to 2-phenylthiophene-3-carbonitriles.

Chitosan-Stabilized Oil-in-Water Nanoemulsions

2022 ◽  
pp. 44-58
Author(s):  
Viktoria Milkova
Keyword(s):  
Physicochemical Characteristics ◽  
Biological Properties ◽  
Precise Control ◽  
Theoretical Approaches ◽  
Natural Polysaccharide ◽  
Oil In Water ◽  
Degree Of Acetylation ◽  
Key Factor ◽  
Potential Applications ◽  
The Stability

Chitosan is a natural polysaccharide and emulsifier that can ensure a significant emulsion stability at suitable pH, ionic strength, composition, concentration, or thermal processing. The evaluation of the electrokinetic properties is a key factor in investigation of the stability of the nanoemulsions with a view to their potential applications in bionanotechnology. Consequently, the precise control over the physicochemical characteristics of chitosan (degree of acetylation, DA and molecular weight, Mw) can provide a high stability and specific biological properties of the developed functional structures. The chapter is focused on the interpretation of the electrokinetic response from nanoemulsion stabilized by adsorption of chitosan (as a polyelectrolyte or uncharged polymer) by using appropriate theoretical approaches.

Preparation of high-performance PEEK anti-wear blends with melt-processable PTFE

2019 ◽  
Vol 32 (6) ◽  
pp. 645-654
Author(s):  
Xiaotao Qiu ◽  
Congli Fu ◽  
Aiqun Gu ◽  
Yang Gao ◽  
Xiuli Wang ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Wear Resistance ◽  
Surface Analysis ◽  
Tribological Properties ◽  
High Performance ◽  
Tribological Performance ◽  
Mechanical And Tribological Properties ◽  
The Past ◽  
Wide Range ◽  
Potential Applications

High-performance anti-wear polyetheretherketone/polytetrafluoroethylene (PEEK/PTFE) blends have drawn much attention over the past few years, owing to their wide range of potential applications. However, a convenient and effective method to prepare such blends with superior mechanical and tribological properties is still lacking. In this work, we propose a promising approach that uses melt-processable PTFE (MP PTFE), instead of conventional PTFE, to prepare anti-wear blends. MP PTFE, with melt flow abilities under appropriate conditions, can disperse homogeneously in PEEK, enhancing both the mechanical and tribological properties of the PEEK/PTFE blend. To prove this postulation, in this work, both MP PTFE and commercial PTFE were blended with PEEK, separately, and the effects of PTFE type and content on the tensile and tribological properties of the blends were studied. The results showed that, although the addition of commercial PTFE to PEEK could increase the wear resistance, it decreased the tensile strength of PEEK significantly. Compared to the blends with commercial PTFE, the blends with MP PTFE exhibited better tribological performance and higher tensile strength for PTFE content below 10 wt%. It was confirmed that the better dispersion of MP PTFE in PEEK endowed the blends with higher tensile strength. The surface analysis indicated that the MP PTFE could readily migrate to and enrich the surfaces of the blends. The relatively high PTFE content on the surface favored the formation of tribo-films, enhancing the tribological properties of the blends.

Separation and characterization of oligomers by reversed-phase high-performance liquid chromatography; a study on well-defined oligothiophenes

2001 ◽  
Vol 911 (1) ◽  
pp. 13-26 ◽  
Author(s):  
E.C Vonk ◽  
B.M.W Langeveld-Voss ◽  
J.L.J van Dongen ◽  
R.A.J Janssen ◽  
H.A Claessens ◽  
...  
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
High Performance ◽  
Reversed Phase

scholarly journals Isolation and Characterization of a Novel Single-Stranded RNA Virus Infecting the Bloom-Forming Diatom Rhizosolenia setigera

2004 ◽  
Vol 70 (2) ◽  
pp. 704-711 ◽  
Author(s):  
Keizo Nagasaki ◽  
Yuji Tomaru ◽  
Noriaki Katanozaka ◽  
Yoko Shirai ◽  
Kensho Nishida ◽  
...  
Keyword(s):  
Host Specificity ◽  
Rna Virus ◽  
Biological Properties ◽  
Rna Molecules ◽  
Isolation And Characterization ◽  
Ssrna Virus ◽  
Ecological Relationship ◽  
Rhizosolenia Setigera ◽  
Species Specific

ABSTRACT A novel single-stranded RNA (ssRNA) virus specifically infecting the bloom-forming diatom Rhizosolenia setigera (R. setigera RNA virus [RsRNAV]) was isolated from Ariake Sea, Japan. Viral replication occurred within the cytoplasm, and the virus particle was icosahedral, lacked a tail, and was 32 nm in diameter on average. The major nucleic acid extracted from the RsRNAV particles was an ssRNA molecule 11.2 kb in length, although smaller RNA molecules (0.6, 1.2, and 1.5 kb) were occasionally observed. The major structural proteins of RsRNAV were 41.5, 41.0, and 29.5 kDa. Inter- and intraspecies host specificity tests revealed that RsRNAV is not only species specific but also strain specific and that its intraspecies host specificity is diverse among virus clones. The latent period of RsRNAV was 2 days, and the burst sizes were 3,100 and 1,010 viruses per host cell when viruses were inoculated into the host culture at the exponential and stationary growth phases, respectively, at 15°C under a 12-h-12-h light-dark cycle of ca. 110 μmol of photons m−2 s−1 with cool white fluorescent illumination. To our knowledge, this is the first report describing the biological properties of a virus infecting a diatom. Further studies on RsRNAV will be helpful in understanding the ecological relationship between diatoms and viruses in nature.

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