scholarly journals A Facile Way for Preparation of Cellulose Beads With High Homogeneity, Low Crystallinity, and Tunable - Internal Structure

2021 ◽  
Author(s):  
Yuanyuan Xia ◽  
Xinping Li ◽  
Yue Yuan ◽  
Jingshun Zhuang ◽  
Wenliang Wang
Keyword(s):  
Crystal Form ◽  
Energy Storage Materials ◽  
Regenerated Cellulose ◽  
Protein Chromatography ◽  
Green Materials ◽  
Coagulation Mechanism ◽  
Structures And Properties ◽  
Water Holding ◽  
Water Alcohol ◽  
Low Crystallinity

Abstract The preparation of cellulose beads has attracted more and more attention in the application of advanced green materials. To obtain uniform and controllable cellulose beads, the dissolving pulp was dissolved in NMMO, and the cellulose beads were regenerated in various coagulation baths (water, alcohol, acid, NMMO, etc.) by phase conversion method. Results show that the crystal form of regenerated cellulose changes from cellulose I to cellulose II. NMMO swelling cellulose beads present low crystallinity and low water holding capacity. The coagulation mechanism of cellulose beads was clarified by a laser confocal microscopy. It is found that the whole coagulation process was from outside to inside gradually. It is a green and facile method for preparing cellulose beads with different structures and properties, which can be widely used in biomedicine, energy storage materials, and protein chromatography.

Modulation of the Structures and Properties of Bacterial Cellulose Film by Fermentation Carbon Sources

2013 ◽  
Vol 647 ◽  
pp. 160-164
Author(s):  
Guang Yang ◽  
Jian Jian Xie
Keyword(s):  
Bacterial Cellulose ◽  
Wound Dressing ◽  
Carbon Sources ◽  
Water Diffusion ◽  
Water Holding Capacity ◽  
Swelling Ratio ◽  
Pure Cellulose ◽  
Structures And Properties ◽  
Water Swelling ◽  
Water Holding

Bacterial cellulose (BC), a natural pure cellulose synthesized by some bacteria, shows great potentials for wound dressing applications. In order to obtain suitable properties, different fermentation carbon sources, i.e. glucose, maltose and sucrose were used to synthesize BC films by static culture. The crystallinity and pore analysis was performed by X-ray diffraction spectroscopy and nitrogen physisorption measurements, respectively. Some important properties of BC materials from different carbon sources were investigated, such as the mechanical strength, water holding capacity, water swelling ratio and water diffusion ability, which were key parameters for wound dressing applications. For comparison, the conventional cotton fiber was used as control. It was found that the carbon sources could change both the structures and properties of BC. The sucrose-derived BC exhibited lower crystallinity, but more suitable mechanical property, higher water holding capacity and water swelling ratio than other samples. All tested BC samples showed higher water holding capacity and water swelling ratio, but lower water diffusion property than the cotton fibers which were expected as good wound-healing biomedical materials.

Crystal structures and properties of two hydrated conglomerate forms of the heart-rate-lowering agent ivabradine hydrochloride

2019 ◽  
Vol 75 (5) ◽  
pp. 545-553
Author(s):  
Xin-Bo Zhou ◽  
Jian-Rong Zhu ◽  
Ji-Yong Liu ◽  
Zhi-Ping Jin ◽  
Fei-Yu Tang ◽  
...  
Keyword(s):  
Crystal Form ◽  
Structural Features ◽  
Monoclinic Space Group ◽  
Orthorhombic Space Group ◽  
Scanning Calorimetry ◽  
Space Group ◽  
Symptomatic Management ◽  
Structures And Properties ◽  
The Stability ◽  
First Time

Ivabradine hydrochloride (IVA-HCl) (systematic name: {[3,4-dimethoxybicyclo[4.2.0]octa-1(6),2,4-trien-7-yl]methyl}[3-(7,8-dimethoxy-2-oxo-2,3,4,5-tetrahydro-1H-3-benzazepin-3-yl)propyl]methylazanium), is a novel medication used for the symptomatic management of stable angina pectoris. In many recent patents, it has been claimed to exist in a very large number of polymorphic, hydrated and solvated phases, although no detailed analysis of the structural features of these forms has been published to date. Here, we have successfully crystallized the tetrahydrate form of IVA-HCl (form β), C27H37N2O5 +·Cl−·4H2O, and elucidated its structure for the first time. Simultaneously, a new crystal form of IVA-HCl, i.e. the hemihydrate (form II), C27H37N2O5 +·Cl−·0.5H2O, was discovered. Its crystal structure was also accurately determined and compared to that of the tetrahydrate form. While the tetrahydrate form of IVA-HCl crystallized in the orthorhombic space group P212121, the new form (hemihydrate) was solved in the monoclinic space group P21. Detailed conformational and packing comparisons between the two forms have allowed us to understand the role of water in the crystal assembly of this hydrochloride salt. The stabilities of the two forms were compared theoretically by calculating the binding energy of the water in the crystal lattice using differential scanning calorimetry (DSC). The stability experiments show that the tetrahydrate is stable under high-humidity conditions, while the hemihydrate is stable under high-temperature conditions.

Structures and properties of low-crystallinity polyolefins modified with nanodiamonds

2015 ◽  
Vol 57 (6) ◽  
pp. 819-828 ◽  
Author(s):  
N. P. Bessonova ◽  
S. V. Krasheninnikov ◽  
A. P. Korobko ◽  
E. A. Tomilina ◽  
M. Yu. Meschankina ◽  
...  
Keyword(s):  
Structures And Properties ◽  
Low Crystallinity

Aragonite growth in water-alcohol mixtures: Classical or nonclassical crystallization?

2012 ◽  
Vol 1419 ◽  
Author(s):  
K. K. Sand ◽  
J. D. Rodriguez-Blanco ◽  
E. Makovicky ◽  
L. G. Benning ◽  
S. L. S. Stipp
Keyword(s):  
Self Assembly ◽  
Crystal Form ◽  
Growth Theory ◽  
Morphological Evidence ◽  
Ambient Conditions ◽  
Carbonate Solutions ◽  
Aragonite Crystal ◽  
Alcohol Mixtures ◽  
Classical Crystal ◽  
Water Alcohol

ABSTRACTAragonite can grow from calcium carbonate solutions as the favored phase, at ambient conditions, in the presence of 1:1 volume % water:ethanol. Its form is single and branched needles, with pseudohexagonal symmetry. Morphological evidence demonstrates that all precipitated aragonite is twinned. The recently popularized hypothesis of nonclassical growth by nanocrystal self assembly cannot describe the aragonite crystal form. Rather, its formation is effectively described as spherulitic growth, i.e. by classical crystal growth theory.

Preparation of Waterborne Polyurethane by Bio-Based Polyol and Study of Nanocomposites with Nanocellulose Particles

2020 ◽  
Vol 20 (8) ◽  
pp. 4873-4877
Author(s):  
Soonmo Choi ◽  
Eunjoo Shin
Keyword(s):  
Waterborne Polyurethane ◽  
Xrd Analysis ◽  
Decomposition Temperature ◽  
Sem Analysis ◽  
Regenerated Cellulose ◽  
Initial Modulus ◽  
A Chain ◽  
Average Size ◽  
20 Nm ◽  
Low Crystallinity

In this study, we environment-friendly developed bio-based waterborne polyurethane (BWPU) through the use of both harmless water to human instead of organic solvent and natural castor oil-based polyols. Also, high crystallinity cellulose nanocrystals (CNCs) and regenerated cellulose nanoparticles (RCNs) with low crystallinity as reinforcing agents were prepared through H2SO4 and NaOH/urea methods, respectively. In SEM analysis, we defined that the CNC rod-like particles have a length of 100~200 nm and a width of several tens nm and that the average size of RCNs with round shape was 7~20 nm. It was shown that the crystallinity of CNCs was higher than RCNs’ via FTIR and XRD analysis. In addition, it was found that as the contents of CNCs and RCNs increased, so did the properties of strength, initial modulus, and strain. It could be established that all results mentioned were constituted by the hydrogen bonding between the -OH group of nanocellulose and the -NCO group of BWPU constitutes as well as the role of nanocellulose as a chain extender. Furthermore, the maximum decomposition temperature increased with raising the content of nanocellulose. This tendency was more favorable for CNCs with higher crystallinity than RCNs with low crystallinity.

Bacterial Cellulose Aerogels Skeleton Strengthened by Regenerated Cellulose

2016 ◽  
Vol 697 ◽  
pp. 143-147
Author(s):  
Rui Fu ◽  
Hua Zheng Sai ◽  
Li Xing ◽  
Jun Hui Xiang ◽  
Zhen You Li ◽  
...  
Keyword(s):  
Bacterial Cellulose ◽  
Freeze Drying ◽  
Compression Modulus ◽  
Crystal Form ◽  
Thin Layers ◽  
Urea Solution ◽  
Regenerated Cellulose ◽  
Cellulose Solution ◽  
Xrd Pattern ◽  
Conformal Coverage

Soft skeleton of bacterial cellulose aerogels (BCAs) was strengthened effectively by conformal coverage of regenerated cellulose to make sure the BCAs sustain more compression. After freeze drying, compression modulus of the strengthened sample is significantly higher than that of the BCAs, which endows the former more extensive applications. The regenerated cellulose solution was prepared by gelation of cellulose from aqueous alkali hydroxide/urea solution. Then the bacterial cellulose wet gels bulks were immersed in the regenerated cellulose solution with different contents to discuss the enhanced effect of the BCAs skeleton. The morphology of the enhanced BCAs was observed by scanning electron micrograph (SEM).The porous structure of the enhanced BCAs was investigated by Brunauer-Emmett-Teller (BET) instrument. The stress−strain curves of the enhanced BCAs were measured. The XRD pattern of the strengthened sample was also carried out. The results indicated that regenerated cellulose forms thin layers which conformally covered bacterial cellulose skeleton fibers and that had little effect on microstructure and crystal form of the bulk cellulose aerogels.

scholarly journals Preparation and Characterization of Regenerated Cellulose Membrane Blended with ZrO2 Nanoparticles

Membranes ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 42
Author(s):  
Xin Huang ◽  
Feng Tian ◽  
Guohong Chen ◽  
Fanan Wang ◽  
Rengui Weng ◽  
...  
Keyword(s):  
Rejection Rate ◽  
Zro2 Nanoparticles ◽  
Inversion Method ◽  
Regenerated Cellulose ◽  
Cellulose Membrane ◽  
Gravimetric Analysis ◽  
Green Materials ◽  
Membrane Flux ◽  
Separation Membrane ◽  
Phase Inversion Method

It is of great significance to search for efficient, renewable, biodegradable and economical membrane materials. Herein, we developed an organic-inorganic hybrid regenerated cellulose membrane (ZrO2/BCM) with excellent hydrophilic and anti-fouling properties. The membrane was prepared by introducing ZrO2 particles into an N-Methylmorpholine-N-oxide(NMMO)/bamboo cellulose(BC) solution system by the phase inversion method. The physi-chemical structure of the membranes were characterized based on thermal gravimetric analysis (TGA), Fourier transform infrared spectroscopy (ATR-FTIR), field emission scanning electron microscopy (FE-SEM), and X-ray diffraction (XRD). The modified regenerated cellulose membrane has the excellent rejection of bovine serum albumin (BSA) and anti-fouling performance. The membrane flux of ZrO2/BCM is 321.49 (L/m2·h), and the rejection rate of BSA is 91.2%. Moreover, the membrane flux recovery rate after cleaning with deionized water was 90.6%. This new type of separation membrane prepared with green materials holds broad application potential in water purification and wastewater treatment.

Structure of Regenerated Celluloses Treated with Ionic Liquids and Comparison of their Enzymatic Digestibility by Purified Cellulase Components

2012 ◽  
Vol 65 (11) ◽  
pp. 1491 ◽  
Author(s):  
Masahiro Mizuno ◽  
Shuji Kachi ◽  
Eiji Togawa ◽  
Noriko Hayashi ◽  
Kouichi Nozaki ◽  
...  
Keyword(s):  
Ionic Liquids ◽  
Crystal Form ◽  
Regenerated Cellulose ◽  
Cellulose Ii ◽  
Cellulose I ◽  
Acid Moiety ◽  
Amino Acid Moiety ◽  
Hydrolysis Of Cellulose ◽  
Hydrolysis Of ◽  
Disordered Chain

In this study, regenerated celluloses were prepared from microcrystalline cellulose (MCC) by treatment with three ionic liquids (ILs) having 1-ethyl-3-methylimidazolium (Emim) as the cation, and the IL N-(2-methoxyethyl)-N,N-diethyl-N-methylammonium alanine ([N221ME][Ala]), where the amino acid moiety is the anion. The crystal form of cellulose was transformed from cellulose I to cellulose II by dissolution with an IL and regeneration with anti-solvent. However, the crystallinity of the regenerated cellulose was different; the disordered chain region was increased in the order of [N221ME][Ala] < [Emim][OAc] < [Emim][DEP] < [Emim][Cl]. The monocomponent cellulase, especially endoglucanase, showed high hydrolyzing activity for regenerated cellulose compared with untreated cellulose. Furthermore, the degree of increase of hydrolyzing activity was almost coincident with the order of crystallinity. For the effective hydrolysis of cellulose treated with an IL, it is necessary to prepare the cellulase mixture containing an adequate ratio of each cellulase component according to crystal allomorph and the crystallinity of regenerated cellulose.

The native structure of the eukaryotic ribosome

1983 ◽  
Vol 41 ◽  
pp. 432-433
Author(s):  
R.A. Milligan ◽  
P.N.T. Unwin
Keyword(s):  
Ribosomal Proteins ◽  
Crystal Form ◽  
Native Structure ◽  
X Ray Diffraction ◽  
Eukaryotic Ribosome ◽  
Vitro Analysis ◽  
In Vitro Analysis ◽  
Resolution Structure ◽  
Stable Unit

A detailed understanding of the mechanism of protein synthesis will ultimately depend on knowledge of the native structure of the ribosome. Towards this end we have investigated the low resolution structure of the eukaryotic ribosome embedded in frozen buffer, making use of a system in which the ribosomes crystallize naturally.The ribosomes in the cells of early chicken embryos form crystalline arrays when the embryos are cooled at 4°C. We have developed methods to isolate the stable unit of these arrays, the ribosome tetramer, and have determined conditions for the growth of two-dimensional crystals in vitro, Analysis of the proteins in the crystals by 2-D gel electrophoresis demonstrates the presence of all ribosomal proteins normally found in polysomes. There are in addition, four proteins which may facilitate crystallization. The crystals are built from two oppositely facing P4 layers and the predominant crystal form, accounting for >80% of the crystals, has the tetragonal space group P4212, X-ray diffraction of crystal pellets demonstrates that crystalline order extends to ~ 60Å.

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