Acetylation of Bacterial Cellulose: Preparation of Cellulose Acetate Having a High Degree of Polymerization

1998 ◽  
Vol 62 (7) ◽  
pp. 1451-1454 ◽  
Author(s):  
Mari TABUCHI ◽  
Kunihiko WATANABE ◽  
Yasushi MORINAGA ◽  
Fumihiro YOSHINAGA
Keyword(s):  
Cellulose Acetate ◽  
Bacterial Cellulose ◽  
Degree Of Polymerization ◽  
High Degree

The Control of Cigarette Smoke Deliveries Using Heat-Shrinkable Films

1975 ◽  
Vol 8 (2) ◽  
Author(s):  
R. A. Crellin ◽  
G. O. Brooks ◽  
H. G. Horsewell
Keyword(s):  
Particulate Matter ◽  
Cellulose Acetate ◽  
Cigarette Smoke ◽  
Total Particulate Matter ◽  
Puff Volume ◽  
Cigarette Paper ◽  
High Degree

AbstractA ventilating filter for cigarettes has been developed which reduces the delivery of smoke constituents from the final two to three puffs. Since the normaI delivery for these three puffs can account for up to half the total particulate matter and nicotine delivered by the whole cigarette, usefuI reductions per cigarette can be produced. The ventilating filter consists of cellulose acetate tow wrapped in heat-shrinkable film and attached to a tobacco rod using perforated tipping paper. When the cigarette is smoked, the perforations remain closed by contact with the impermeable film until transfer of heat to the filter is sufficient to soften the filter tow and shrink the film. Ventilating air now enters the cigarette and reduces the smoke deliveries. The effectiveness of the ventilating filter is increased by using films which have a low shrink temperature, high shrink tension and a high degree of biaxiaI shrinkage. Increases in filter plasticiser level, tipping perforation area and puff volume improve the effectiveness of the ventilating filter but increases in cigarette paper porosity and tobacco butt length reduce the effectiveness

Properties and Applications of Modified Bacterial Cellulose-Based Materials

2020 ◽  
Vol 16 ◽  
Author(s):  
Munair Badshah ◽  
Hanif Ullah ◽  
Fazli Wahid ◽  
Taous Khan
Keyword(s):  
Surface Modification ◽  
Bacterial Cellulose ◽  
Degree Of Polymerization ◽  
Biomedical Science ◽  
Hydroxyl Groups ◽  
Market Demand ◽  
Ideal Candidate ◽  
Fibrous Network ◽  
Potential Applications ◽  
Surface Modification Techniques

Background: Bacterial cellulose (BC) is purest form of cellulose as it is free from pactin, lignin, hemicellulose and other active constituents associated with cellulose derived from plant sources. High biocompatibility and easy molding into desired shape make BC an ideal candidate for applications in biomedical field such as tissue engineering, wound healing and bone regeneration. In addition to this, BC has been widely studied for applications in the delivery of proteins and drugs in various forms via different routes. However, BC lacks therapeutic properties and resistance to free movement of small molecules i.e., gases and solvents. Therefore, modification of BC is required to meet the research ad market demand. Methods: We have searched the updated data relevant to as-synthesized and modified BC, properties and applications in various fields using Web of science, Science direct, Google and PubMed. Results: As-synthesized BC possesses properties such as high crystallinity, well organized fibrous network, higher degree of polymerization, and ability of being produced in swollen form. The large surface area with abundance of free accessible hydroxyl groups makes BC an ideal candidate for carrying out surface functionalization to enhance its features. The various reported surface modification techniques including, but not limited to, are amination, methylation and acetylation. Conclusion: In this review, we have highlighted various approaches made for BC surface modification. We have also reported enhancement in the properties of modified BC and potential applications in different fields ranging from biomedical science to drug delivery and paper-making to various electronic devices.

scholarly journals Processive action of cellobiohydrolase Cel7A from Trichoderma reesei is revealed as ‘burst’ kinetics on fluorescent polymeric model substrates

2005 ◽  
Vol 385 (2) ◽  
pp. 527-535 ◽  
Author(s):  
Kalle KIPPER ◽  
Priit VÄLJAMÄE ◽  
Gunnar JOHANSSON
Keyword(s):  
Bacterial Cellulose ◽  
Trichoderma Reesei ◽  
Anthranilic Acid ◽  
Degree Of Polymerization ◽  
Cellulose Substrates ◽  
Quantitative Monitoring ◽  
End Groups ◽  
Alternative Means ◽  
Burst Kinetics ◽  
Hydrolysis Of

Reaction conditions for the reducing-end-specific derivatization of cellulose substrates with the fluorogenic compound, anthranilic acid, have been established. Hydrolysis of fluorescence-labelled celluloses by cellobiohydrolase Cel7A from Trichoderma reesei was consistent with the active-site titration kinetics (burst kinetics), which allowed the quantification of the processivity of the enzyme. The processivity values of 88±10, 42±10 and 34±2.0 cellobiose units were found for Cel7A acting on labelled bacterial cellulose, bacterial microcrystalline cellulose and endoglucanase-pretreated bacterial cellulose respectively. The anthranilic acid derivatization also provides an alternative means for estimating the average degree of polymerization of cellulose and, furthermore, allows the quantitative monitoring of the production of reducing end groups on solid cellulose on hydrolysis by cellulases. Hydrolysis of bacterial cellulose by cellulases from T. reesei revealed that, by contrast with endoglucanase Cel5A, neither cellobiohydrolases Cel7A nor Cel6A produced detectable amounts of new reducing end groups on residual cellulose.

scholarly journals Use of Electrosprayed Agave Fructans as Nanoencapsulating Hydrocolloids for Bioactives

Nanomaterials ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 868 ◽  
Author(s):  
Jorge Ramos-Hernández ◽  
Juan Ragazzo-Sánchez ◽  
Montserrat Calderón-Santoyo ◽  
Rosa Ortiz-Basurto ◽  
Cristina Prieto ◽  
...  
Keyword(s):  
Uv Light ◽  
Particle Morphology ◽  
Bioactive Compound ◽  
Processing Parameters ◽  
Degree Of Polymerization ◽  
Spherical Particles ◽  
Sem Images ◽  
High Degree ◽  
Thermal Stability Of ◽  
Β Carotene

High degree of polymerization Agave fructans (HDPAF) are presented as a novel encapsulating material. Electrospraying coating (EC) was selected as the encapsulation technique and β-carotene as the model bioactive compound. For direct electrospraying, two encapsulation methodologies (solution and emulsion) were proposed to find the formulation which provided a suitable particle morphology and an adequate concentration of β-carotene encapsulated in the particles to provide a protective effect of β-carotene by the nanocapsules. Scanning electron microscopy (SEM) images showed spherical particles with sizes ranging from 440 nm to 880 nm depending on the concentration of HDPAF and processing parameters. FTIR analysis confirmed the interaction and encapsulation of β-carotene with HDPAF. The thermal stability of β-carotene encapsulated in HDPAF was evidenced by thermogravimetric analysis (TGA). The study showed that β-carotene encapsulated in HDPAF by the EC method remained stable for up to 50 h of exposure to ultraviolet (UV) light. Therefore, HDPAF is a viable option to formulate nanocapsules as a new encapsulating material. In addition, EC allowed for increases in the ratio of β-carotene:polymer, as well as its photostability.

scholarly journals Anatomy and fructan distribution in vegetative organs of Dimerostemma vestitum (Asteraceae) from the campos rupestres

2015 ◽  
Vol 87 (2) ◽  
pp. 797-812 ◽  
Author(s):  
Taiza M. Silva ◽  
Divina A.A. Vilhalva ◽  
Moemy G. Moraes ◽  
Rita de Cássia L. Figueiredo-Ribeiro
Keyword(s):  
Glandular Trichomes ◽  
Polarized Light ◽  
Degree Of Polymerization ◽  
Campos Rupestres ◽  
Water Restriction ◽  
Secretory Structures ◽  
Vegetative Organs ◽  
Semi Arid Region ◽  
Aerial Stem ◽  
High Degree

Among the compounds stored by plants, several functions are assigned to fructans, such as source of energy and protection against drought and extreme temperatures. In the present study we analyzed the anatomy and distribution of fructans in vegetative organs of Dimerostemma vestitum (Asteraceae), an endemic species from the Brazilian campos rupestres. D. vestitum has amphistomatic and pubescent leaves, with both glandular and non-glandular trichomes. In the basal aerial stem the medulla has two types of parenchyma, which differ from the apical portion. The xylopodium has mixed anatomical origin. Interestingly, although inulin-type fructans with high degree of polymerization were found in all analyzed organs except the leaves, the highest amount and maximum degree of polymerization were detected in the xylopodium. Inulin sphero-crystals were visualized under polarized light in the medulla and in the vascular tissues mainly in the central region of the xylopodium, which has abundant xylem parenchyma. Secretory structures accumulating several compounds but not inulin were identified within all the vegetative organs. The presence of these compounds, in addition to inulin, might be related to the strategies of plants to survive adverse conditions in a semi-arid region, affected seasonally by water restriction and frequently by fire.

High Degree of Polymerization in a Fullerene-Containing Supramolecular Polymer

2014 ◽  
Vol 126 (22) ◽  
pp. 5735-5739 ◽  
Author(s):  
Helena Isla ◽  
Emilio M. Pérez ◽  
Nazario Martín
Keyword(s):  
Degree Of Polymerization ◽  
Supramolecular Polymer ◽  
High Degree

Glass Hydration Mechanisms with Application to Obsidian Hydration Dating

1988 ◽  
Vol 123 ◽  
Author(s):  
William B. White
Keyword(s):  
Infrared Spectroscopy ◽  
Three Dimensional ◽  
Depth Profiling ◽  
Structural Disorder ◽  
Degree Of Polymerization ◽  
Concentration Profiles ◽  
Surface Layers ◽  
Profiling Techniques ◽  
High Degree ◽  
Depth Concentration

AbstractChemical analysis of typical obsidians place them with a group of silica- and alumina-rich glasses constructed of a three dimensional framework of silica and alumina tetrahedra with nearly all tetrahedra sharing corners. Raman and infrared spectra of unweathered obsidians confirm the high degree of polymerization as well as some additional structural disorder. Analysis of dissolution rates of various glasses shows obsidian to be among the most stable, comparable to the most durable synthetic glasses. Surface layers on glasses can be chemically characterized by depth-profiling techniques such as SIMS and SIPS that give depth-concentration profiles for individual elements. Hydration rinds on glasses can be structurally characterized by infrared spectroscopy which shows both hydration and re-polymerization as the rinds age. Because obsidians are already completely polymerized glasses, their hydration rinds are mainly a result of hydrolysis and alkali exchange.

Germplasm evaluation to obtain inulin with high degree of polymerization in Mediterranean environment

2019 ◽  
Vol 34 (1) ◽  
pp. 187-191 ◽  
Author(s):  
M.G. Melilli ◽  
F. Branca ◽  
C. Sillitti ◽  
S. Scandurra ◽  
P. Calderaro ◽  
...  
Keyword(s):  
Degree Of Polymerization ◽  
Germplasm Evaluation ◽  
Mediterranean Environment ◽  
High Degree
Sign in / Sign up

Export Citation Format

Share Document