scholarly journals Effect of Cellulose Characteristics on the Properties of the Wet-Spun Aerogel Fibers

2021 ◽  
Vol 11 (4) ◽  
pp. 1525
Author(s):  
Matin Rostamitabar ◽  
Gunnar Seide ◽  
Stefan Jockenhoevel ◽  
Samaneh Ghazanfari
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Surface Area ◽  
Biomedical Application ◽  
Wound Care ◽  
Textural Properties ◽  
High Specific Surface Area ◽  
Fiber Spinning ◽  
Limiting Factor ◽  
High Porosity

Cellulose aerogels (CAs) from plant or bacterial-derived cellulose have advantages such as low density, high porosity, and high specific surface area and have been used in various applications including biomedical fields. One limiting factor in developing CAs is their demanding shaping process since it involves several steps of dissolution/dispersion of cellulose, geometry configurations using molds or nozzles, coagulation and washing of the gel body, and drying techniques. CA fibers can be converted into textiles and enhance the design ability, stiffness, and flexibility of the CAs. This study aims to understand the correlations between the initial cellulose characteristics, aerogel’s internal structure, and its prospective biomedical application. Wet-spun CA fibers were obtained by supercritical CO2 drying from low and high molecular weight microcrystalline cellulose in calcium thiocyanate tetrahydrate solution. Fiber spinning, thermal behavior, textural properties, and biological assessments of the CA fibers were inspected. The CA microfibers from high molecular weight cellulose proved to have a higher surface area (~197 m2/g), denser structure, and finer nanofibrils (~2 nm) with better thermal stability in comparison with the fibers produced from low molecular weight cellulose. The fibers were nontoxic, and cell proliferation was observed over time. CA fibers showed promising results to be used for biomedical applications such as tissue engineering and wound care.

Mixing of Carbon Black with Rubber. VI. Analysis of NR/SBR Blends

1988 ◽  
Vol 61 (4) ◽  
pp. 609-618 ◽  
Author(s):  
George R. Cotten ◽  
Lawrence J. Murphy
Keyword(s):  
Molecular Weight ◽  
Carbon Black ◽  
High Molecular Weight ◽  
Surface Area ◽  
Bound Rubber ◽  
Very High

Abstract The distribution of carbon black in NR/SBR blends was determined through the analysis of bound rubber. The NR/SBR blends were found to be very different from the previously studied SBR/BR compounds: these differences were assigned to mutual insolubility of the two polymers and a very high molecular weight of NR. In NR/SBR blends, it was found that changes in molecular weight of the polymer has no effect on the carbon black distribution in the blend. While the “activity” of carbon black did not affect the distribution, the loading of the black in NR decreased linearly with increasing surface area of the black. Approximately 35% of normal tread blacks (surface area 80–100 m2/g) was found in the NR phase. However, the bond between NR and carbon black is quite weak, and black continues to migrate into the SBR phase on prolonged mixing or during blending of NR and SBR masterbatches.

Effect of variations of CuIIX2/L, surface area of Cu0, solvent, and temperature on atom transfer radical polyaddition of 4-vinylbenzyl 2-bromo-2-isobutyrate inimers

RSC Advances ◽  
2016 ◽  
Vol 6 (57) ◽  
pp. 51816-51822 ◽  
Author(s):  
Chih-Feng Huang ◽  
Shiao-Wei Kuo ◽  
Daniela Moravčíková ◽  
Jyun-Ci Liao ◽  
Yu-Min Han ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Surface Area ◽  
Atom Transfer ◽  
Catalytic Systems

Optimization of atom transfer radical polyadditions using commercially available catalytic systems allowed obtaining control over the polyester architecture and functionality and functional linear polyesters with high molecular weight (Mw = 16 200).

scholarly journals Porosity model and pore evolution of transitional shales: an example from the Southern North China Basin

2020 ◽  
Vol 17 (6) ◽  
pp. 1512-1526
Author(s):  
Xiao-Guang Yang ◽  
Shao-Bin Guo
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Clay Minerals ◽  
Clay Mineral ◽  
Specific Surface Area ◽  
Mineral Content ◽  
High Specific Surface Area ◽  
High Porosity ◽  
Mechanical Compaction ◽  
Pore Evolution

AbstractThe evolution of shale reservoirs is mainly related to two functions: mechanical compaction controlled by ground stress and chemical compaction controlled by thermal effect. Thermal simulation experiments were conducted to simulate the chemical compaction of marine-continental transitional shale, and X-ray diffraction (XRD), CO2 adsorption, N2 adsorption and high-pressure mercury injection (MIP) were then used to characterize shale diagenesis and porosity. Moreover, simulations of mechanical compaction adhering to mathematical models were performed, and a shale compaction model was proposed considering clay content and kaolinite proportions. The advantage of this model is that the change in shale compressibility, which is caused by the transformation of clay minerals during thermal evolution, may be considered. The combination of the thermal simulation and compaction model may depict the interactions between chemical and mechanical compaction. Such interactions may then express the pore evolution of shale in actual conditions of formation. Accordingly, the obtained results demonstrated that shales having low kaolinite possess higher porosity at the same burial depth and clay mineral content, proving that other clay minerals such as illite–smectite mixed layers (I/S) and illite are conducive to the development of pores. Shales possessing a high clay mineral content have a higher porosity in shallow layers (< 3500 m) and a lower porosity in deep layers (> 3500 m). Both the amount and location of the increase in porosity differ at different geothermal gradients. High geothermal gradients favor the preservation of high porosity in shale at an appropriate Ro. The pore evolution of the marine-continental transitional shale is divided into five stages. Stage 2 possesses an Ro of 1.0%–1.6% and has high porosity along with a high specific surface area. Stage 3 has an Ro of 1.6%–2.0% and contains a higher porosity with a low specific surface area. Finally, Stage 4 has an Ro of 2.0%–2.9% with a low porosity and high specific surface area.

scholarly journals Highly porous Co-doped NiO nanorods: facile hydrothermal synthesis and electrocatalytic oxygen evolution properties

2021 ◽  
Vol 8 (9) ◽  
pp. 202352
Author(s):  
Nguyen Duc Cuong ◽  
Tien D. Tran ◽  
Quyen T. Nguyen ◽  
Ho Van Minh Hai ◽  
Tran Thai Hoa ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Surface Area ◽  
Oxygen Evolution ◽  
Alkaline Medium ◽  
Active Sites ◽  
High Specific Surface Area ◽  
High Porosity ◽  
Metal Oxide Nanostructures ◽  
Highly Porous ◽  
Co Doped

Highly porous 3d transition metal oxide nanostructures are opening up the exciting area of oxygen evolution reaction (OER) catalysts in alkaline medium thanks to their good thermal and chemical stability, excellent physiochemical properties, high specific surface area and abundant nanopores. In this paper, highly porous Co-doped NiO nanorods were successfully synthesized by a simple hydrothermal method. The porous rod-like nanostructures were preserved with the added cobalt dopant ranging from 1 to 5 at% but were broken into aggregated nanoparticles at higher concentrations of additional cobalt. The catalytic activity of Co-doped NiO nanostructures for OER in an alkaline medium was assayed. The 5%Co-NiO sample showed a drastically enhanced activity. This result could originate from the combination of advantageous characteristics of highly porous NiO nanorods such as large surface area and high porosity as well as the important role of Co dopant that could provide more catalytic active sites, leading to an enhanced catalytic activity of the nanocatalyst.

scholarly journals Porous Carrageenan-Derived Carbons for Efficient Ciprofloxacin Removal from Water

Nanomaterials ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 1004 ◽  
Author(s):  
João Nogueira ◽  
Maria António ◽  
Sergey Mikhalev ◽  
Sara Fateixa ◽  
Tito Trindade ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Porous Carbon ◽  
Carbon Materials ◽  
Activated Carbons ◽  
Chemical Activation ◽  
High Specific Surface Area ◽  
High Porosity ◽  
Porous Carbon Materials

Porous carbon materials derived from biopolymers are attractive sorbents for the removal of emerging pollutants from water, due to their high specific surface area, high porosity, tunable surface chemistry, and reasonable cost. However, carrageenan biopolymers were scarcely investigated as a carbon source to prepare porous carbon materials. Herein, hydrochars (HCs) and porous activated carbons (ACs) derived from natural occurring polysaccharides with variable sulfate content (κ-, ι- and λ-carrageenan) were prepared and investigated in the uptake of ciprofloxacin, which is an antibiotic detected in water sources and that poses serious hazards to public health. The materials were prepared using hydrothermal carbonization and subsequent chemical activation with KOH to increase the available surface area. The activated carbons were markedly microporous, presenting high specific surface area, up to 2800 m2/g. Activated carbons derived from κ- and λ-carrageenan showed high adsorption capacity (422 and 459 mg/g, respectively) for ciprofloxacin and fast adsorption kinetics, reaching the sorption equilibrium in approximately 5 min. These features place the ACs investigated here among the best systems reported in the literature for the removal of ciprofloxacin from water.

Aerosol-Assisted Sol-Gel Synthesis of Mesoporous TiO2 Materials, and Their Use as Support for Ru-Based Methanation Catalysts

2019 ◽  
Author(s):  
Ara Kim ◽  
Clément Sanchez ◽  
Bernard Haye ◽  
Cédric Boissière ◽  
Capucine Sassoye ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Self Assembly ◽  
Sol Gel ◽  
Textural Properties ◽  
High Specific Surface Area ◽  
Spherical Particles ◽  
Aerosol Process ◽  
Evaporation Induced Self Assembly

<div>Mesoporous TiO<sub>2</sub> materials have been prepared by an aerosol process, which leverages on the acetic acid-mediated sol-gel chemistry and on the evaporation-induced self-assembly phenomenon to obtain materials with high specific surface area and large mesoporous volume. The obtained spherical particles are calcined to release the porosity. It is shown that the mesoscopic order can be preserved when the calcination is carried out at relatively low temperature (375 °C and below). Harsher calcination conditions lead to the progressive destruction of the mesostructured, concomitant with a progressive drop of textural properties and with the crystallization of larger anatase domains. The mesoporous TiO<sub>2</sub> material calcined at 350°C (specific surface area = 260 m².g<sup>-1</sup>; pore volume = 0.36 cm³.<sup>-1</sup>; mean pore diameter = 5.4 nm) was selected as a promising support for preformed RuO<sub>2</sub> nanoparticles, and subsequently annealed in air. It is shown that the presence of RuO<sub>2</sub> nanoparticles and subsequent annealing provoke further intense modification of the texture and crystallinity of the TiO<sub>2</sub> materials. In addition to a drop in the textural parameters, a RuO<sub>2</sub>-mediated crystallization of rutile TiO<sub>2</sub> is highlighted at temperature as low as 250°C. After an in situ reduction in H<sub>2</sub>, the catalysts containing TiO<sub>2</sub> rutile and relatively small RuO<sub>2</sub> crystals showed the highest activity in the methanation of CO<sub>2</sub>. </div>

Aerosol-Assisted Sol-Gel Synthesis of Mesoporous TiO2 Materials, and Their Use as Support for Ru-Based Methanation Catalysts

2019 ◽  
Author(s):  
Ara Kim ◽  
Clément Sanchez ◽  
Bernard Haye ◽  
Cédric Boissière ◽  
Capucine Sassoye ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Self Assembly ◽  
Sol Gel ◽  
Textural Properties ◽  
High Specific Surface Area ◽  
Spherical Particles ◽  
Aerosol Process ◽  
Evaporation Induced Self Assembly

<div>Mesoporous TiO<sub>2</sub> materials have been prepared by an aerosol process, which leverages on the acetic acid-mediated sol-gel chemistry and on the evaporation-induced self-assembly phenomenon to obtain materials with high specific surface area and large mesoporous volume. The obtained spherical particles are calcined to release the porosity. It is shown that the mesoscopic order can be preserved when the calcination is carried out at relatively low temperature (375 °C and below). Harsher calcination conditions lead to the progressive destruction of the mesostructured, concomitant with a progressive drop of textural properties and with the crystallization of larger anatase domains. The mesoporous TiO<sub>2</sub> material calcined at 350°C (specific surface area = 260 m².g<sup>-1</sup>; pore volume = 0.36 cm³.<sup>-1</sup>; mean pore diameter = 5.4 nm) was selected as a promising support for preformed RuO<sub>2</sub> nanoparticles, and subsequently annealed in air. It is shown that the presence of RuO<sub>2</sub> nanoparticles and subsequent annealing provoke further intense modification of the texture and crystallinity of the TiO<sub>2</sub> materials. In addition to a drop in the textural parameters, a RuO<sub>2</sub>-mediated crystallization of rutile TiO<sub>2</sub> is highlighted at temperature as low as 250°C. After an in situ reduction in H<sub>2</sub>, the catalysts containing TiO<sub>2</sub> rutile and relatively small RuO<sub>2</sub> crystals showed the highest activity in the methanation of CO<sub>2</sub>. </div>

scholarly journals Synthesis of high-molecular-weight aliphatic polycarbonates by organo-catalysis

2016 ◽  
Vol 7 (8) ◽  
pp. 1642-1649 ◽  
Author(s):  
Jingjiang Sun ◽  
Dirk Kuckling
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Biomedical Application ◽  
Low Toxicity ◽  
Good Biocompatibility ◽  
Significant Attention

Aliphatic polycarbonates have attracted significant attention for biomedical application over the last few years due to their biodegradability, low toxicity and good biocompatibility.

Microtubule motors and other maps

1990 ◽  
Vol 48 (3) ◽  
pp. 1-1
Author(s):  
Richard B. Vallee
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Cytoplasmic Dynein ◽  
Organelle Transport ◽  
Structural Components ◽  
Microtubule Associated Proteins ◽  
Microtubule Motors ◽  
Associated Proteins ◽  
The Subject ◽  
Intracellular Motility

Microtubules are involved in a number of forms of intracellular motility, including mitosis and bidirectional organelle transport. Purified microtubules from brain and other sources contain tubulin and a diversity of microtubule associated proteins (MAPs). Some of the high molecular weight MAPs - MAP 1A, 1B, 2A, and 2B - are long, fibrous molecules that serve as structural components of the cytamatrix. Three MAPs have recently been identified that show microtubule activated ATPase activity and produce force in association with microtubules. These proteins - kinesin, cytoplasmic dynein, and dynamin - are referred to as cytoplasmic motors. The latter two will be the subject of this talk.Cytoplasmic dynein was first identified as one of the high molecular weight brain MAPs, MAP 1C. It was determined to be structurally equivalent to ciliary and flagellar dynein, and to produce force toward the minus ends of microtubules, opposite to kinesin.

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