scholarly journals Production and Mechanical Characterisation of TEMPO-Oxidised Cellulose Nanofibrils/β-Cyclodextrin Films and Cryogels

Molecules ◽  
2020 ◽  
Vol 25 (10) ◽  
pp. 2381
Author(s):  
Bastien Michel ◽  
Julien Bras ◽  
Alain Dufresne ◽  
Ellinor B. Heggset ◽  
Kristin Syverud
Keyword(s):  
Mechanical Properties ◽  
Water Sorption ◽  
Biomedical Applications ◽  
Freeze Drying ◽  
Cellulose Nanofibrils ◽  
Added Value ◽  
Active Principle ◽  
Acidic Ph ◽  
Sorption Behaviour ◽  
The Impact

Wood-based TEMPO-oxidised cellulose nanofibrils (toCNF) are promising materials for biomedical applications. Cyclodextrins have ability to form inclusion complexes with hydrophobic molecules and are considered as a method to bring new functionalities to these materials. Water sorption and mechanical properties are also key properties for biomedical applications such as drug delivery and tissue engineering. In this work, we report the modification with β-cyclodextrin (βCD) of toCNF samples with different carboxyl contents viz. 756 ± 4 µmol/g and 1048 ± 32 µmol/g. The modification was carried out at neutral and acidic pH (2.5) to study the effect of dissociation of the carboxylic acid group. Films processed by casting/evaporation at 40 °C and cryogels processed by freeze-drying were prepared from βCD modified toCNF suspensions and compared with reference samples of unmodified toCNF. The impact of modification on water sorption and mechanical properties was assessed. It was shown that the water sorption behaviour for films is driven by adsorption, with a clear impact of the chemical makeup of the fibres (charge content, pH, and adsorption of cyclodextrin). Modified toCNF cryogels (acidic pH and addition of cyclodextrins) displayed lower mechanical properties linked to the modification of the cell wall porosity structure. Esterification between βCD and toCNF under acidic conditions was performed by freeze-drying, and such cryogels exhibited a lower decrease in mechanical properties in the swollen state. These results are promising for the development of scaffold and films with controlled mechanical properties and added value due to the ability of cyclodextrin to form an inclusion complex with active principle ingredient (API) or growth factor (GF) for biomedical applications.

Cellulose Nanofibrils-based Hydrogels for Biomedical Applications: Progresses and Challenges

2020 ◽  
Vol 27 (28) ◽  
pp. 4622-4646 ◽  
Author(s):  
Huayu Liu ◽  
Kun Liu ◽  
Xiao Han ◽  
Hongxiang Xie ◽  
Chuanling Si ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Metal Ion ◽  
Biomedical Applications ◽  
Biomedical Application ◽  
Cellulose Nanofibrils ◽  
Wound Dressings ◽  
Preparation Methods ◽  
Tissue Scaffold ◽  
Surface Areas ◽  
Mechanical Methods

Background: Cellulose Nanofibrils (CNFs) are natural nanomaterials with nanometer dimensions. Compared with ordinary cellulose, CNFs own good mechanical properties, large specific surface areas, high Young's modulus, strong hydrophilicity and other distinguishing characteristics, which make them widely used in many fields. This review aims to introduce the preparation of CNFs-based hydrogels and their recent biomedical application advances. Methods: By searching the recent literatures, we have summarized the preparation methods of CNFs, including mechanical methods and chemical mechanical methods, and also introduced the fabrication methods of CNFs-based hydrogels, including CNFs cross-linked with metal ion and with polymers. In addition, we have summarized the biomedical applications of CNFs-based hydrogels, including scaffold materials and wound dressings. Results: CNFs-based hydrogels are new types of materials that are non-toxic and display a certain mechanical strength. In the tissue scaffold application, they can provide a micro-environment for the damaged tissue to repair and regenerate it. In wound dressing applications, it can fit the wound surface and protect the wound from the external environment, thereby effectively promoting the healing of skin tissue. Conclusion: By summarizing the preparation and application of CNFs-based hydrogels, we have analyzed and forecasted their development trends. At present, the research of CNFs-based hydrogels is still in the laboratory stage. It needs further exploration to be applied in practice. The development of medical hydrogels with high mechanical properties and biocompatibility still poses significant challenges.

scholarly journals A Study on Water Absorption and Mechanical Properties in Epoxy-Bamboo Laminate Composite with Varying Immersion Temperatures

2020 ◽  
Vol 10 (1) ◽  
pp. 814-819
Author(s):  
Indah Widiastuti ◽  
Yuniar Ratna Pratiwi ◽  
Dwi Noor Cahyo
Keyword(s):  
Mechanical Properties ◽  
Water Absorption ◽  
Water Sorption ◽  
Elevated Temperatures ◽  
Water Immersion ◽  
Life Time ◽  
Gravimetric Analysis ◽  
Laminate Composites ◽  
Sorption Behaviour ◽  
Bamboo Fibre

AbstractBamboo laminate composites could be the alternative materials in outdoor application. However, the life time prediction of this composite in humid environment became a concern considering hydrophilic property of the bamboo fibre. This research aimed to assess the changes of mechanical properties in the composite with the sorption of water. It employed hand lay-up method in developing the laminate composites with epoxy as the matrix and woven bamboo as the reinforced material. Water sorption characteristic was evaluated through a gravimetric analysis for different water immersion temperatures. The sorption on water was studied by four weeks immersion in room temperature as well as in elevated temperatures of 50∘ and 80∘C. Tensile test was performed to evaluate the mechanical properties of the composite. This research clearly showed the significant effect of bamboo fibre on the strength and water sorption behaviour of the composites. It was observed that the rate of water absorption depends on temperature of immersion. Larger debonding between the bamboo fibre and the epoxy matrix was found in higher water immersion temperature. The results of this study emphasized the importance of considering the deterioration of mechanical properties in outdoor applications of bamboo composite highly exposed to high temperature and humidity

scholarly journals Bio-based films/nanopapers of banana tree pseudostem: From lignocellulosic wastes to added-value micro/nanomaterials

2021 ◽  
Author(s):  
Barbara Maria Ribeiro Guimarães ◽  
Mário Vanoli Scatolino ◽  
Maria Alice Martins ◽  
Saulo Rocha Ferreira ◽  
Lourival Marin Mendes ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Raw Materials ◽  
Cellulose Nanofibrils ◽  
Dry Mass ◽  
Added Value ◽  
Light Transmittance ◽  
Transparent Films ◽  
Banana Tree ◽  
Lignocellulosic Wastes ◽  
Mechanical Fibrillation

Abstract The growing demand for products with lower environmental impact and the extensive applicability of cellulose nanofibrils (CNFs) have received attention in several fields of knowledge due to their attractive properties. In this study, bio-based films/nanopapers were produced with CNFs from banana tree pseudostem (BTPT) wastes and Eucalyptus kraft cellulose (EKC) and were evaluated by their properties, such as mechanical strength, biodegradability and light transmittance. The CNFs were produced by mechanical fibrillation (after 20 and 40 passages) from suspensions of BTPT (alkaline pre-treated) and EKC. Films/nanopapers were produced by casting from both suspensions with concentrations of 2% (based in dry mass of CNF). The BTPT films/nanopapers showed greater mechanical properties, with Young’s modulus and tensile strength around 2.42 GPa and 51 MPa (after 40 passages), respectively. On the other hand, the EKC samples showed lower disintegration in water after 24 h and biodegradability. The increase in the number of fibrillation cycles produced more transparent films/nanopapers and caused a significant reduction of water absorption for both raw materials. The permeability was similar for the films/nanopapers from BTPT and EKC. This study indicated that attractive mechanical properties and biodegradability could be achieved by bio-based nanomaterials, with potential for being applied as emulsifying agents and special membranes, enabling more efficient utilization of agricultural wastes.

3D bioprinting of dual-crosslinked nanocellulose hydrogels for tissue engineering applications

2021 ◽  
Author(s):  
Marzieh Monfared ◽  
Damia Mawad ◽  
Jelena Rnjak-Kovacina ◽  
Martina Heide Stenzel
Keyword(s):  
Mechanical Properties ◽  
Tissue Engineering ◽  
Biomedical Applications ◽  
Cellulose Nanofibrils ◽  
3D Bioprinting ◽  
Engineering Applications ◽  
The Poor

Hydrogels based on cellulose nanofibrils (CNFs) have been widely used as scaffolds for biomedical applications, however, the poor mechanical properties of CNFs hydrogels limit their use as ink for 3D...

Successful Implementation Of Geomechanics In Deep Water Setting: A Case Study From KG Offshore, India

2021 ◽  
Author(s):  
Sarah Bhimpalli ◽  
Ashok Shinde ◽  
Bayye L Rao ◽  
Satya Perumalla ◽  
Anjana Panchakarla ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Deep Water ◽  
Added Value ◽  
Reservoir Rock ◽  
Successful Implementation ◽  
Drilling Mud ◽  
Geomechanical Model ◽  
Rock Mechanical Properties ◽  
The Impact

Abstract Geomechanics has an important role in assessing formation integrity during well construction and completion. It also has its effect when the wellbore is in production mode. Geomechanical study evaluate the impact of the present day in-situ stress and related mechanical processes on reservoir management. The study field ‘K' belongs to Plio-Pleistocene sequence of deep-water environment with hydrocarbon prospects. This belongs to Post-Rift tectonic stage of evolution with hydrocarbon occurring in structurally controlled traps. As a part of exploration activity, four offset oil wells were drilled earlier which were considered for the geomechanical model construction. Field (K) development plan comprising of six hydrocarbon producers and four water injectors was prepared. Considering the thick water column (300m-650m) in this deep water area of offshore and young unconsolidated sedimentary sequence in the sub-surface, expected pore-pressures can be high whereas the fracture gradient can be low. As a result, the safe drilling mud window can be narrow. Upon successful drilling of a well in such challenging environment without NPT (Non-Productive time), completing the well with best possible technologies suitable to the reservoir's mechanical behavior is utmost important for maximizing the production and minimizing the risk. To mitigate these problems in developing this field, an integrated reservoir geomechanics approach is adopted to optimize the drilling plan and reservoir completion parameters for the planned well. This paper covers the geomechanical study of four wells namely W, X, Y & Z drilled in the field ‘K'. The principal constituents of the geomechanical model are in-situ stresses, pore pressure and the rock mechanical properties. Geomechanical model for the field ‘K' was built utilizing the available data by integrating drilling, geology, petrophysics and reservoir data. Methodology adopted in this paper also highlights how a reliable geomechanical model can be built for a field, which is having data constraints. Constraining of stress magnitudes, orientation and anisotropy added value for efficient well planning in deep waters reservoirs. Calculating well specific reservoir rock mechanical properties, it made possible to identify the most optimal completion strategy. Approach contributed knowledge of geomechanical parameters based on the data of four offset wells has been used for successfully drilling and completion of all the subsequent wells without major challenges. Overall, geomechanical modeling has played a major role in drillability and deliverability of the reservoir. Integrated approach adopted in this paper can be used for well planning and drilling of future wells in East Coast of India with similar geological set up.

scholarly journals The influence of heartwood, sapwood and density on moisture fluctuations and crack formations of coated Norway spruce in outdoor exposure

2019 ◽  
Vol 65 (1) ◽  
Author(s):  
T. Sjökvist ◽  
Å. Blom ◽  
M. E. P. Wålinder
Keyword(s):  
Norway Spruce ◽  
Water Sorption ◽  
Moisture Sorption ◽  
Outdoor Exposure ◽  
High Density ◽  
Sorption Behaviour ◽  
Wetting Properties ◽  
Film Forming ◽  
Similar Density ◽  
The Impact

Abstract The moisture sorption behaviour of wood strongly influences the durability of exterior-coated wood. Wood characteristics are known to influence the water sorption of uncoated wood. Despite this, the majority of the research on coated wood has been focused on the coating properties. This study aims to investigate the impact of heartwood, sapwood and density on the moisture content (MC) and crack formation of coated Norway spruce (Picea abies (L.) Karst.). Boards with film-forming coatings or a non-film-forming coating were exposed outdoors during 3 years. Crack development and the mass of the boards were recorded during this period. Heartwood and sapwood samples showed no differences in MC. Thus, a coating seems to reduce the differences in water sorption behaviour that is present in uncoated heartwood and sapwood spruce. The reduction is probably related to wetting properties and different sorption mechanisms, involving free and bond water diffusion. However, the low-density samples had significantly higher MC levels than the high-density samples. The high-density samples with a non-film-forming coating showed a higher number of cracks than those with lower density. Furthermore, sapwood samples had a remarkably high number of cracks when compared to the corresponding heartwood samples, despite a similar density and MC.

scholarly journals Impact of the Freeze-Drying Conditions Applied to Obtain an Orange Snack on Energy Consumption

Foods ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 2756
Author(s):  
Marilú Andrea Silva-Espinoza ◽  
María del Mar Camacho ◽  
Javier Martínez-Monzó ◽  
Nuria Martínez-Navarrete
Keyword(s):  
Energy Consumption ◽  
Freeze Drying ◽  
Gum Arabic ◽  
Economic Cost ◽  
Added Value ◽  
Process Conditions ◽  
Drying Time ◽  
Freeze Dried ◽  
Secondary Drying ◽  
The Impact

Nowadays, the consumer is looking for healthier, more attractive, ready-to-eat, and safer foodstuffs than fresh products. Despite freeze drying being known for providing high added value products, it is a slow process which is conducted at low pressures, so, in terms of energy consumption, it turns out to be quite costly for the food industry. With the purpose of obtaining a freeze-dried orange puree, previously formulated with gum Arabic and bamboo fiber, which can be offered to consumers as a snack at a low economic cost, the impact of the process conditions on energy consumption has been considered. The product temperature evolution and the energy consumption were registered during the drying of frozen samples at different combinations of chamber pressures (5 and 100 Pa) and shelf temperatures (30, 40 and 50 °C). In each case, the time processing was adapted in order to obtain a product with a water content under 5 g water/100 g product. In this study, the secondary drying stage was considered to start when the product reached the shelf temperature and both the pressure and the temperature affected the duration of primary and secondary drying stages. The results obtained led to the conclusion that the shorter duration of the process when working at 50 °C results in significant energy saving. Working at a lower pressure also contributes to a shortening of the drying time, thus reducing the energy consumption: the lower the temperature, the more marked the effect of the pressure.

Effect of combined drink cans and steel fibers on the impact resistance and mechanical properties of concrete

2020 ◽  
Vol 14 (2) ◽  
pp. 6734-6742
Author(s):  
A. Syamsir ◽  
S. M. Mubin ◽  
N. M. Nor ◽  
V. Anggraini ◽  
S. Nagappan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Reinforced Concrete ◽  
Impact Resistance ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Fiber Reinforced ◽  
Indirect Tensile ◽  
The Impact

This study investigated the combine effect of 0.2 % drink cans and steel fibers with volume fractions of 0%, 0.5%, 1%, 1.5%, 2%, 2.5% and 3% to the mechanical properties and impact resistance of concrete. Hooked-end steel fiber with 30 mm and 0.75 mm length and diameter, respectively was selected for this study.  The drinks cans fiber were twisted manually in order to increase friction between fiber and concrete. The results of the experiment showed that the combination of steel fibers and drink cans fibers improved the strength performance of concrete, especially the compressive strength, flexural strength and indirect tensile strength. The results of the experiment showed that the combination of steel fibers and drink cans fibers improved the compressive strength, flexural strength and indirect tensile strength by 2.3, 7, and 2 times as compare to batch 1, respectively. Moreover, the impact resistance of fiber reinforced concrete has increase by 7 times as compared to non-fiber concretes. Moreover, the impact resistance of fiber reinforced concrete consistently gave better results as compared to non-fiber concretes. The fiber reinforced concrete turned more ductile as the dosage of fibers was increased and ductility started to decrease slightly after optimum fiber dosage was reached. It was found that concrete with combination of 2% steel and 0.2% drink cans fibers showed the highest compressive, split tensile, flexural as well as impact strength.    

scholarly journals Effect of Freeze Drying and Simulated Gastrointestinal Digestion on Phenolic Metabolites and Antioxidant Property of the Natal Plum (Carissa macrocarpa)

Foods ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1420
Author(s):  
Faith Seke ◽  
Vimbainashe E. Manhivi ◽  
Tinotenda Shoko ◽  
Retha M. Slabbert ◽  
Yasmina Sultanbawa ◽  
...  
Keyword(s):  
Freeze Drying ◽  
Array Detector ◽  
Gastrointestinal Digestion ◽  
Liquid Chromatograph ◽  
Antioxidant Power ◽  
Intestinal Phase ◽  
Glucosidase Activity ◽  
Freeze Dried ◽  
Small Intestinal ◽  
The Impact

Natal plums (Carissa macrocarpa) are a natural source of bioactive compounds, particularly anthocyanins, and can be consumed as a snack. This study characterized the impact of freeze drying and in vitro gastrointestinal digestion on the phenolic profile, antioxidant capacity, and α-glucosidase activity of the Natal plum (Carissa macrocarpa). The phenolic compounds were quantified using high performance liquid chromatography coupled to a diode-array detector HPLC-DAD and an ultra-performance liquid chromatograph (UPLC) with a Waters Acquity photodiode array detector (PDA) coupled to a Synapt G2 quadrupole time-of-flight (QTOF) mass spectrometer. Cyanidin-3-O-β-sambubioside (Cy-3-Sa) and cyanidin-3-O-glucoside (Cy-3-G) were the dominant anthocyanins in the fresh and freeze-dried Natal plum powder. Freeze drying did not affect the concentrations of both cyanidin compounds compared to the fresh fruit. Both cyanidin compounds, ellagic acid, catechin, epicatechin syringic acid, caffeic acid, luteolin, and quercetin O-glycoside from the ingested freeze-dried Natal plum powder was quite stable in the gastric phase compared to the small intestinal phase. Cyanidin-3-O-β-sambubioside from the ingested Natal plum powder showed bioaccessibility of 32.2% compared to cyanidin-3-O-glucoside (16.3%). The degradation of anthocyanins increased the bioaccessibility of gallic acid, protocatechuic acid, coumaric acid, and ferulic acid significantly, in the small intestinal digesta. The ferric reducing antioxidant power (FRAP), 2,2′-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) activities, and inhibitory effect of α-glucosidase activity decreased in the small intestinal phase. Indigenous fruits or freeze-dried powders with Cy-3-Sa can be a better source of anthocyanin than Cy-3-G due to higher bioaccessibility in the small intestinal phase.

Sign in / Sign up

Export Citation Format

Share Document