scholarly journals STRUCTURAL CHARACTERIZATION OF AGAR EXTRACTED FROM SIX RED SEAWEED SPECIES GROWING IN THE COAST OF VIETNAM

2017 ◽  
Vol 25 (2) ◽  
pp. 395-403
Author(s):  
Tran Thi Thanh Van ◽  
Bui Minh Ly ◽  
Ngo Quoc Buu ◽  
Chu Dinh Kinh
Keyword(s):  
Structural Characterization ◽  
Algal Species ◽  
Gel Strength ◽  
Raw Material ◽  
Spectroscopic Methods ◽  
Red Seaweed ◽  
Seaweed Species ◽  
Coast Of Vietnam ◽  
Agar Production

Polysaccharides extracted from six red seaweed species growing in Vietnam have been studied. Characterisation of their structure by chemical and spectroscopic methods showed that all of them have a basic repeating structure of alternating 3-linked b-D-galactopyranosyl and 4-linked 3,6-anhydro a-L-galactopyranosyl units with substituted methyl ether groups.   The native agar offers only weak gelling abilities owing to the 4-linked a-L-galactopyranosyl 6-sulfate as its precursor. Conversion of this unit into the corresponding 3,6-anhydride by treating with hot alkali generally led to gel strength increasing. The agars from G. fisheri and G. firma are poorly substituted, while those from G.asiatica, G.tenustipitata and G. heteroclada are partly methylated on position 6 of the 3-linked b-D- galactose. Agar from Gelidiella acerosa is partlly methylated on both positions 6 and 2 of the 4linked 3,6-anhydro a-L-galactose.   The alkali- modified agars have been obtained in acceptable quantities with gel strength of 300932 g/cm2. The obtained results showed that all the six algal species are suitable as raw material for commercial agar production and worthy of further cultivation

scholarly journals Structural characterization of polysaccharide obtained from red seaweed Gracilaria caudata (J Agardh)

2013 ◽  
Vol 92 (1) ◽  
pp. 598-603 ◽  
Author(s):  
Francisco C.N. Barros ◽  
Draulio C. da Silva ◽  
Venicios G. Sombra ◽  
Jeanny S. Maciel ◽  
Judith P.A. Feitosa ◽  
...  
Keyword(s):  
Structural Characterization ◽  
Red Seaweed

scholarly journals Synthesis and Structural Characterization of Amidine, Amide, Urea and Isocyanate Derivatives of the Amino-closo-dodecaborate Anion [B12H11NH3]−

Molecules ◽  
2018 ◽  
Vol 23 (12) ◽  
pp. 3137 ◽  
Author(s):  
Yuanbin Zhang ◽  
Yuji Sun ◽  
Tao Wang ◽  
Jiyong Liu ◽  
Bernhard Spingler ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Structural Characterization ◽  
Spectroscopic Methods ◽  
Fundamental Interest ◽  
Derivatives Of

The synthesis and structural characterization of new derivatives of [B12H12]2− is of fundamental interest and is expected to allow for extended applications. Herein we report on the synthesis of a series of amidine, amide, urea and isocyanate derivatives based on the amino-closo-dodecaborate anion [B12H11NH3]−. Their structures have been confirmed by spectroscopic methods, and nine crystal structures are presented.

scholarly journals Structural Characterization of the Released Polysaccharide of Desiccation-Tolerant Nostoc communeDRH-1

2000 ◽  
Vol 182 (4) ◽  
pp. 974-982 ◽  
Author(s):  
Richard F. Helm ◽  
Zebo Huang ◽  
Devin Edwards ◽  
Heidi Leeson ◽  
William Peery ◽  
...  
Keyword(s):  
Rheological Properties ◽  
Structural Characterization ◽  
Uronic Acid ◽  
Glucuronic Acid ◽  
Extracellular Polysaccharide ◽  
Spectroscopic Methods ◽  
Nostoc Commune ◽  
Geographic Locations ◽  
Released Polysaccharide

ABSTRACT The structure of the viscous extracellular polysaccharide (glycan) of desiccation-tolerant Nostoc commune DRH-1 was determined through chromatographic and spectroscopic methods. The polysaccharide is novel in that it possesses a 1-4-linked xylogalactoglucan backbone with d-ribofuranose and 3-O-[(R)-1-carboxyethyl]-d-glucuronic acid (nosturonic acid) pendant groups. The presence ofd-ribose and nosturonic acid as peripheral groups is unusual, and their potential roles in modulating the rheological properties of the glycan are discussed. Nosturonic acid was present in the glycans of N. commune from diverse geographic locations, suggesting that this uronic acid is an integral component of this cosmopolitan anhydrophile.

Structural Characterization of Ethylene-Propylene-Diene Rubbers by High-Resolution Pyrolysis Gas Chromatography

1990 ◽  
Vol 63 (2) ◽  
pp. 191-201 ◽  
Author(s):  
T. Yamada ◽  
T. Okumoto ◽  
H. Ohtani ◽  
S. Tsuge
Keyword(s):  
Gas Chromatography ◽  
Structural Characterization ◽  
Fused Silica ◽  
Sequence Length ◽  
Spectroscopic Methods ◽  
Pyrolysis Gas ◽  
Ethylene Propylene ◽  
Pyrolysis Gas Chromatography ◽  
Diene Rubbers

Abstract Ethylene-propylene-diene rubbers (EPDMs) are now used for various purposes because of their excellent resistance to ozone, weather, and heat. Therefore, many kinds of EPDMs are provided as commercial polymers. Consequently, reliable methods for the structural characterization of EPDM have been needed in the fields of material development, process control, and quality assurance of the cured products. The iodine value method is generally used to determine the diene content in EPDMs. However, it is too time consuming to be a routine method. Until now, spectroscopic methods such as IR and NMR are generally used for the study of the composition and the sequence length distributions in EPDMs. Levine and Haines determined the content of ethylidenenorbornene (ENB) in ethylene-propylene-ethylidenenorbornene rubbers (ENB-EPDMs) by IR. Florence and Loustalot investigated ethylene-propylene-1.4-hexadiene rubbers by NMR. However, these spectroscopic methods often encountered the difficulties in the analysis of vulcanized rubbers since they were insoluble and usually contained many kinds of additives such as curing agents, plasticizers, stabilizers, and fillers. On the other hand, owing to the recent development of excellent pyrolyzers and highly efficient fused-silica capillary columns, pyrolysis-gas chromatography (PyGC) has become a powerful tool to give unique information about structures of high polymers. Furthermore, PyGC is advantageous to the practical analysis of insoluble polymeric materials such as vulcanized rubbers.

New ultrastructural findings about Borrelia burgdorferi by cryofixation, negative staining, thin sectioning and scanning techniques

1990 ◽  
Vol 48 (3) ◽  
pp. 582-583
Author(s):  
S. F. Hayes ◽  
M. D. Corwin ◽  
T. G. Schwan ◽  
D. W. Dorward ◽  
W. Burgdorfer
Keyword(s):  
Lyme Disease ◽  
Borrelia Burgdorferi ◽  
Structural Characterization ◽  
Negative Staining ◽  
Low Speed ◽  
Thin Sectioning ◽  
Ultrastructural Findings

Characterization of Borrelia burgdorferi strains by means of negative staining EM has become an integral part of many studies related to the biology of the Lyme disease organism. However, relying solely upon negative staining to compare new isolates with prototype B31 or other borreliae is often unsatisfactory. To obtain more satisfactory results, we have relied upon a correlative approach encompassing a variety EM techniques, i.e., scanning for topographical features and cryotomy, negative staining and thin sectioning to provide a more complete structural characterization of B. burgdorferi.For characterization, isolates of B. burgdorferi were cultured in BSK II media from which they were removed by low speed centrifugation. The sedimented borrelia were carefully resuspended in stabilizing buffer so as to preserve their features for scanning and negative staining. Alternatively, others were prepared for conventional thin sectioning and for cryotomy using modified procedures. For thin sectioning, the fixative described by Ito, et al.

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