scholarly journals Three Polymers from the Sea: Unique Structures, Directional Modifications, and Medical Applications

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2482
Author(s):  
Lei Wang ◽  
Wenjun Li ◽  
Song Qin
Keyword(s):  
Performance Improvement ◽  
Material Properties ◽  
Mechanical Performance ◽  
Extraction Process ◽  
Clinical Applications ◽  
Marine Organisms ◽  
The Poor ◽  
Extraction Processes ◽  
Body Damage ◽  
Research Hotspots

With the increase of wounds and body damage, the clinical demand for antibacterial, hemostatic, and repairable biomaterials is increasing. Various types of biomedical materials have become research hotspots. Of these, and among materials derived from marine organisms, the research and application of alginate, chitosan, and collagen are the most common. Chitosan is mainly used as a hemostatic material in clinical applications, but due to problems such as the poor mechanical strength of a single component, the general antibacterial ability, and fast degradation speed research into the extraction process and modification mainly focuses on the improvement of the above-mentioned ability. Similarly, the research and modification of sodium alginate, used as a material for hemostasis and the repair of wounds, is mainly focused on the improvement of cell adhesion, hydrophilicity, degradation speed, mechanical properties, etc.; therefore, there are fewer marine biological collagen products. The research mainly focuses on immunogenicity removal and mechanical performance improvement. This article summarizes the source, molecular structure, and characteristics of alginate, chitosan, and collagen from marine organisms; and introduces the biological safety, clinical efficacy, and mechanism of action of these materials, as well as their extraction processes and material properties. Their modification and other issues are also discussed, and their potential clinical applications are examined.

Effect of Material Properties on the Mechanical Performance of Nitinol Esophageal Stent: Finite Element Analysis

2013 ◽  
Vol 773-774 ◽  
pp. 9-17
Author(s):  
Fardin Nematzadeh ◽  
Sayed Khatiboleslam Sadrnezhaad ◽  
A.H. Kokabi ◽  
M. Razani ◽  
A.H. Mohagheghi
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Material Properties ◽  
Mechanical Performance ◽  
Gastrointestinal Diseases ◽  
Clinical Applications ◽  
Main Approach ◽  
Element Analysis ◽  
Nitinol Wire ◽  
Element Simulation

Stent placement has been a main approach to treat gastrointestinal diseases during past decade. Nitinol superelastic stents have been considered as a solution to such difficulties as restenosis after implantation, low twisting ability, inadequate radial mechanical strength and inappropriate dynamic behaviors associated with the ducts. In this paper, effects of Aftemperatures on mechanical performance of z-shaped Nitinol wire stent under crimping test for clinical applications are investigated by finite element simulation. Having 60% crimping and high radial resistive strength, favorable superelastic behaviors are attained at Aftemperature of 22°C. The performance of the stent is seen to be drastically different with a mere change of 1° in the segments angle.

scholarly journals Designing Materials and Processes for Strong Polyacrylonitrile Precursor Fibers

Polymers ◽  
2021 ◽  
Vol 13 (17) ◽  
pp. 2863
Author(s):  
Hyunchul Ahn ◽  
Sang Young Yeo ◽  
Byoung-Sun Lee
Keyword(s):  
Carbon Fibers ◽  
Material Properties ◽  
Mechanical Performance ◽  
Superior Performance ◽  
Materials Processing ◽  
Effective Strategy ◽  
Precursor Fiber ◽  
Polyacrylonitrile Precursor

Although polyacrylonitrile (PAN)-based carbon fibers have been successfully commercialized owing to their excellent material properties, their actual mechanical performance is still much lower than the theoretical values. Meanwhile, there is a growing demand for the use of superior carbon fibers. As such, many studies have been conducted to improve the mechanical performance of carbon fibers. Among the various approaches, designing a strong precursor fiber with a well-developed microstructure and morphology can constitute the most effective strategy to achieve superior performance. In this review, the efforts used to modulate materials, processing, and additives to deliver strong precursor fibers were thoroughly investigated. Our work demonstrates that the design of materials and processes is a fruitful pathway for the enhancement of the mechanical performance of carbon fibers.

First application of different Chlorella sp. microalgal strains for the treatment of vegetation waters derived from unconventional oil extractions enriched with citrus byproducts

2021 ◽  
Author(s):  
Carolina Chiellini ◽  
Monica Macaluso ◽  
Adriana Ciurli ◽  
Lorenzo Guglielminetti ◽  
Isabella Taglieri ◽  
...  
Keyword(s):  
Phenolic Compounds ◽  
Olive Oil ◽  
Low Cost ◽  
Environmental Pollutants ◽  
Extraction Process ◽  
Total Phenolic ◽  
Mediterranean Countries ◽  
Extraction Processes ◽  
The Mediterranean ◽  
Vegetation Water

The Mediterranean diet has among its cornerstones the use of olive oil for its nutraceutical and organoleptic properties. Despite the numerous merits, olive-oil mill wastewater (OMWW), which is generated by the olive-oil extraction process, is one of the most serious environmental pollutants in the Mediterranean countries. The polluting potential of OMWW is due to its high content of tannins, polyphenols, polyalcohols, pectins and lipids. In this experiment, we tested the ability of five microalgae of the Chlorella group (SEC_LI_ChL_1, CL-Sc, CL-Ch, FB and Idr) in lowering the percentage of total phenolic compounds in vegetation water. In order to close the recovery cycle of a fortified citrus olive oils previously developed, we tested the vegetation wa-ter obtained with three different extraction processes (conventional, lemon and orange peels) at three concentrations each (10%, 25% and 50%). Results showed that strains Idr, FB and CL-Sc from the Lake Massaciuccoli can tolerate vegetation water from conventional and lemon peels extraction up to 25%; these strains can also reduce the phenolic compounds within the tests. The results demonstrate that the application of microalgae for OMWW treatment represent an inter-esting opportunity, and an eco-friendly low-cost solution to be developed within the companies as a full-scale approach.

scholarly journals Extraction of Antioxidants from Blackberry (Rubus ulmifolius L.): Comparison between Ultrasound- and Microwave-Assisted Extraction Techniques

Agronomy ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 745 ◽  
Author(s):  
Estrella Espada-Bellido ◽  
Marta Ferreiro-González ◽  
Ceferino Carrera ◽  
Miguel Palma ◽  
José A. Álvarez ◽  
...  
Keyword(s):  
Extraction Process ◽  
Total Phenolic ◽  
Antioxidant Compounds ◽  
Extraction Techniques ◽  
Potential Health ◽  
Assisted Extraction ◽  
Total Anthocyanins ◽  
Precision Study ◽  
Extraction Processes ◽  
High Concentrations

Berries are considered functional food because of their potential health benefits to consumers due to their high concentrations in bioactive compounds. The extraction process of their antioxidant compounds is a crucial step. In this work, ultrasound (UAE) and microwave (MAE) assisted extraction have been evaluated and compared for the recovery of total phenolic compounds (TPC) and total anthocyanins (TA) from blackberry. Since several variables have an influence on the extraction processes efficiency, a response surface method using a Box–Behnken design (BBD) was chosen for the optimization of UAE and MAE variables. Six variables (solvent, temperature, amplitude, cycle, pH, and sample:solvent ratio) were optimized for UAE while the optimization for MAE was performed on four variables (solvent, temperature, pH, and sample:solvent ratio). It has been proven that solvent and temperature have a significant influence on the extraction of both TA and TPC. Only 10 and 5 min were necessary to complete the UAE and MAE procedures, respectively. A precision study was also carried out, and coefficient of variation lower than 5% was determined. Non-significant differences were obtained when using UAE and MAE at their respective optimum conditions. Thus, the results demonstrated a successful potential use of both techniques for the extraction of TA and TPC from blackberry. In conclusion, this work shows interesting perspectives for quality control analytical laboratories for the development of rapid extraction techniques to quantify these antioxidant compounds in blackberries.

The Effects of Layer-by-Layer Thickness and Fiber Volume Fraction Variation on the Mechanical Performance of a Pressure Vessel

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Emre Özaslan ◽  
Ali Yetgin ◽  
Bülent Acar ◽  
Volkan Coşkun ◽  
Tarık Olğar
Keyword(s):  
Finite Element ◽  
Pressure Vessel ◽  
Material Properties ◽  
Fiber Volume Fraction ◽  
Mechanical Performance ◽  
Volume Fraction ◽  
Element Model ◽  
Layer By Layer ◽  
Fiber Volume ◽  
Filament Wound

Abstract Due to high stiffness/weight ratio, composite materials are widely used in aerospace applications such as motor case of rockets which can be regarded as a pressure vessel. The most commonly used method to manufacture pressure vessels is the wet filament winding. However, the mechanical performance of a filament wound pressure vessel directly depends on the manufacturing process, manufacturing site environmental condition, and material properties of matrix and fiber. The designed pressure vessel may not be manufactured because of the mentioned issues. Therefore, manufacturing of filament wound composite structures are based on manufacturing experience and experiment. In this study, effects of layer-by-layer thickness and fiber volume fraction variation due to manufacturing process on the mechanical performance were investigated for filament wound pressure vessel with unequal dome openings. First, the finite element model was created for designed thickness dimensions and constant material properties for all layers. Then, the model was updated. The updated finite element model considered the thickness of each layer separately and variation of fiber volume fraction between the layers. Effects of the thickness and fiber volume fraction on the stress distribution along the motor axial direction were shown. Also hydrostatic pressurization tests were performed to verify finite element analysis in terms of fiber direction strain through the motor case outer surface. Important aspects of analyzing a filament wound pressure vessel were addressed for designers.

scholarly journals Mechanical Properties of Steels for Cold-Formed Steel Structures at Elevated Temperatures

2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Zhen Nie ◽  
Yuanqi Li ◽  
Yehua Wang
Keyword(s):  
Mechanical Properties ◽  
Material Properties ◽  
Elevated Temperatures ◽  
Elasticity Modulus ◽  
Mechanical Performance ◽  
Strain Curve ◽  
Steel Structures ◽  
Test Method ◽  
Stress Relieving ◽  
Cold Formed Steel

It is highly important to clarify the high-temperature mechanical properties in the design of cold-formed steel (CFS) structures under fire conditions due to the unique deterioration feature in material properties under fire environment and associated reduction to the mechanical performance of members. This paper presents the mechanical properties of widely used steels for cold-formed steel structures at elevated temperatures. The coupons were extracted from original coils of proposed full annealed steels (S350 and S420, with nominal yielding strengths 280 MPa and 350 MPa) and proposed stress relieving annealed steels (G500, with nominal yielding strength 500 MPa) for CFS structures with thickness of 1.0 mm and 1.2 mm, and a total of nearly 50 tensile tests were carried out by steady-state test method for temperatures ranging from 20 to 700°C. Based on the tests, material properties including the yield strengths, ultimate strengths, the elasticity modulus, and the stress-strain curve were obtained. Meanwhile, the ductility of steels for CFS structures was discussed. Then, the temperature-dependent retention factors of yield strengths and elasticity modulus were compared to those provided by design codes and former researchers. Finally, a set of prediction equations of the mechanical properties for steels for CFS structures at elevated temperatures was proposed depending on existing tests data.

scholarly journals Crystalline Structure, Synthesis, Properties and Applications of Potassium Hexatitanate: A Review

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4132 ◽  
Author(s):  
Patricia Ponce-Peña ◽  
Martha Poisot ◽  
Alicia Rodríguez-Pulido ◽  
María Azucena González-Lozano
Keyword(s):  
Material Properties ◽  
Mechanical Performance ◽  
Synthesis Method ◽  
Tunnel Structure ◽  
Chemical Formula ◽  
New Materials ◽  
Structure Synthesis ◽  
Synthesis Properties ◽  
New Applications ◽  
Potassium Hexatitanate

Potassium hexatitanate (PHT) with chemical formula K2Ti6O13 has a tunnel structure formed by TiO2 octahedra sharing edges or corners and with the potassium atoms located in the tunnels. This material has attracted great interest in the areas of photocatalysis, reinforcement of materials, biomaterials, etc. This work summarizes a large number of studies about methods to prepare PHT since particle size can be modified from millimeter to nanometric scale according to the applied method. Likewise, the synthesis method has influenced the material properties as band-gap and the final mechanical performance of composites when the reinforcement is PHT. The knowing of synthesis, properties and applications of PHT is worthwhile for the design of new materials and for the development of new applications taking advantage of their inherent properties.

Expansion Level of Steel Slag Aggregate Effects on Both Material Properties and Asphalt Mixture Performance

2019 ◽  
Vol 2673 (3) ◽  
pp. 506-515 ◽  
Author(s):  
Jamilla Emi Sudo Lutif Teixeira ◽  
Aecio Guilherme Schumacher ◽  
Patrício Moreira Pires ◽  
Verônica Teixeira Franco Castelo Branco ◽  
Henrique Barbosa Martins
Keyword(s):  
Material Properties ◽  
Mechanical Performance ◽  
Early Stage ◽  
Asphalt Binder ◽  
Steel Slag ◽  
Asphalt Mixture ◽  
Asphalt Mixtures ◽  
Mix Design ◽  
Expansion Level ◽  
Different Levels

The influence of steel slag expansion level on the early stage performance of hot mix asphalt (HMA) is evaluated. Initially, samples of Linz-Donawitz type steel slag with different levels of expansion (6.71%, 3.16%, 1.33%) were submitted to physical, mechanical, and morphological characterization to assess the effects of expansion on individual material properties. Steel slag was then used as aggregate in HMA to verify the effects of its expansion characteristics on the volumetric and mechanical performance of the asphalt mixture. Four different asphalt mixtures were designed based on Marshall mix design, using asphalt cement (pen. grade 50/70), natural aggregate (granite), and steel slag (in three different levels of expansion). The mechanical characteristics of the asphalt mixture were evaluated based on results from Marshall stability, indirect tensile strength, and resilient modulus testing. A modified Pennsylvania testing method (PTM) was also performed on the studied asphalt mixtures to verify the potential of asphalt binder film to minimize the expansive reactions of steel slag. It was observed that the level of steel slag expansion changes some of the material’s individual properties, which can affect the volumetric parameters of the mix design. The use of steel slag as aggregate in HMA also improves the mechanical properties of non-aged asphalt mixtures. Moreover, the expansive characteristics of this material could be minimized when combined with other asphalt mixture components.

scholarly journals Utilization of Dynamic and Physical Properties of Ice in Underground Mining Operations

1977 ◽  
Vol 19 (81) ◽  
pp. 672 ◽  
Author(s):  
Henning Fangel
Keyword(s):  
Underground Mining ◽  
Complete Recovery ◽  
Extraction Process ◽  
Wall Material ◽  
Mining Operations ◽  
Left Behind ◽  
Winter Temperatures ◽  
Extraction Processes ◽  
Natural Freezing ◽  
Lateral Walls

Abstract In sub-level caving mining operations, the lateral walls cave in. This results in dilution of the mineral content of the produced ore by 15%-20% waste rock. Also 15%-20% of the valuable ores are lost in the caved wall material that is left behind in the mined-out rooms. Placing ice, in the form of a small glacier, in the mine-room before the lateral walls start to cave, permit complete recovery of ore reserves without dilution. The glacier will advance at a rate permitted by ore extraction processes, in accordance with glaciological theories and laws. Volumes of ice that are required may be calculated from ore extraction rates, power consumed in the mine, ventilating air volumes and temperatures, specific heat and thermal conductivity of the lateral rock. The required ice volumes can be produced through natural freezing of water, where the winter temperatures regularly fall below 0°C for a predictable period every winter. Use of ice as a mining aid reduces costs of the ore extraction process by about one-third and increases value of the produced ore by about 20%. Thus, the value of a given orebody is increased by about 30% relative to the values experienced in the most efficient mines of today.

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