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Polyamide

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https://www.readbyqxmd.com/read/30319929/solvent-free-method-for-the-copolymerization-of-labile-sugar-derived-building-blocks-into-polyamides
#1
Aleksandra A Wróblewska, Sander Stevens, Wessel Garsten, Stefaan M A De Wildeman, Katrien V Bernaerts
This research focuses on the preparation of biobased copolyamides containing biacetalized galactaric acid (GalX), namely, 2,3:4,5-di- O -isopropylidene-galactaric acid (GalXMe) and 2,3:4,5-di- O -methylene-galactaric acid (GalXH), in bulk by melt polycondensation of salt monomers. In order to allow the incorporation of temperature-sensitive sugar-derived building blocks into copolyamides at temperatures below the degradation temperature of the monomers and below their melting temperatures, a clever selection of salt monomers is required, such that the sugar-derived salt monomer dissolves in the other salt monomers...
October 1, 2018: ACS Sustainable Chemistry & Engineering
https://www.readbyqxmd.com/read/30309018/surface-area-evaluation-of-electrically-conductive-polymer-based-textiles
#2
Lukas Vojtech, Marek Neruda, Tomas Reichl, Karel Dusek, Cristina de la Torre Megías
In this paper, the surface area of coated polymer-based textiles, i.e., copper and nickel plated woven polyester fabric, copper and acrylic coated woven polyester fabric, and copper and acrylic coated non-woven polyamide fabric, is investigated. In order to evaluate the surface area of the woven fabrics, Peirce's geometrical model of the interlacing point and measurement using an electron microscope are used. Non-woven fabrics are evaluated using an optical method, handmade method, and MATLAB functions. An electrochemical method, based on the measurement of the resistance between two electrodes, is used for relative comparison of the effective surface area of the coated woven and non-woven fabrics...
October 10, 2018: Materials
https://www.readbyqxmd.com/read/30308342/a-novel-height-adjustable-nano-hydroxyapatite-polyamide-66-vertebral-body-for-reconstruction-of-thoracolumbar-structural-stability-after-spinal-tumor-resection
#3
Guanghui Chen, Mengchen Yin, Weibo Liu, Jian Wang, Jing Wang, Xin Gao, Guangjian Bai, Ge Liu, Yiwei Hu, Yang Wang, Chao Liu, Li Cheng, Jianru Xiao, Tielong Liu
BACKGROUND: Reconstruction of thoracolumbar structural stability is a formidable challenge for spine surgeons after vertebral body tumor resection. Various disadvantages of the currently used expandable or non-expandable cages have limited their clinical applications. OBJECTIVE: To develop a novel prosthesis for clinical use and assess its preliminary clinical outcome in reconstruction of thoracolumbar structural stability after spinal tumor resection. METHODS: Based on the data obtained from a retrospective analysis of the morphological characteristics of the thoracolumbar vertebrae and endplates in previously published articles, we modified the nano hydroxyapatite/polyamide-66 (n-HA/PA66) strut into a novel height adjustable vertebral body...
October 8, 2018: World Neurosurgery
https://www.readbyqxmd.com/read/30306811/potential-pharmacobezoar-formation-of-large-size-extended-release-tablets-and-their-dissolution-an-in-vitro-study
#4
Lotte Christine Groth Hoegberg, Frank Refsgaard, Steen Hauge Pedersen, Mark Personne, Shahid Ullah, Georgios Panagiotidis, Tonny Studsgaard Petersen, Anita Annas
OBJECTIVE: Extended release (ER) tablets/capsules in massive ingestion overdoses are prone to form pharmacobezoars potentially increasing the risk of late-appearing toxic effects and prolonged symptoms. Oral activated charcoal is often sufficient to prevent drug absorption, but in a recent massive ingestion of highly toxic substances, prior orogastric lavage might be considered. The disintegration characteristics of ER preparations in overdose situations is valuable to understand if the time line and course of the intoxication might be prolonged, but information on these characteristics are unavailable...
October 11, 2018: Clinical Toxicology
https://www.readbyqxmd.com/read/30301058/microplastics-analysis-in-malaysian-marine-waters-a-field-study-of-kuala-nerus-and-kuantan
#5
Wan Mohd Afiq Wan Mohd Khalik, Yusof Shuaib Ibrahim, Sabiqah Tuan Anuar, Sharumathiy Govindasamy, Nor Fadilah Baharuddin
The first report on the emergence of microplastic in Malaysian marine waters was documented in this study. Water samples were collected from two regions, namely Kuala Nerus and Kuantan port, as the representatives of different anthropogenic activities. Identification of microplastic was performed based on physical characteristics (colour, shape, density) and chemical characterisation (ATR-FTIR analysis) for a functional group of polymers. Fragment type, black or grey colour and high density (>1.02 g cm-3 ) of microplastic were the most prevalent characteristics found in both areas...
October 2018: Marine Pollution Bulletin
https://www.readbyqxmd.com/read/30300691/deformable-liposomes-for-skin-therapy-with-human-epidermal-growth-factor-the-effect-of-liposomal-surface-charge
#6
Selenia Ternullo, Purusotam Basnet, Ann Mari Holsæter, Gøril Eide Flaten, Louis de Weerd, Nataša Škalko-Basnet
The topical administration of exogenous human epidermal growth factor (hEGF) is a promising approach for improved chronic wound therapy. To develop therapeutically superior hEGF formulation, we prepared hEGF-containing neutral (NDLs), cationic (CDLs) and anionic (ADLs) deformable liposomes (DLs), respectively, since it is expected that the liposomal surface charge can affect both the liposomal physicochemical properties, their skin penetration potential and therapeutic efficacy of liposome-associated drug. All prepared liposomes were of similar size (300-350 nm) with high hEGF load (~80% entrapment efficacy)...
October 7, 2018: European Journal of Pharmaceutical Sciences
https://www.readbyqxmd.com/read/30298102/synthesis-and-characterization-of-ionene-polyamide-materials-as-candidates-for-new-gas-separation-membranes
#7
Jason E Bara, Kathryn E O'Harra, Marlow M Durbin, Grayson P Dennis, Enrique M Jackson, Brian Thomas, Jamiu A Odutola
A new family of six ionenes containing aromatic amide linkages has been synthesized from ready available starting materials at scales up to ~50 g. These ionene-polyamides are all constitutional isomers and vary only in the regiochemistry of the amide linkages (para, meta) and xylyl linkages (ortho, meta, para) which are present in the polymer backbone. This paper details the synthesis of these ionenes and associated characterizations. Ionene-polyamides exhibit relatively low melting points (~150 oC) allowing them to be readily processed into films and other objects...
2018: MRS Advances
https://www.readbyqxmd.com/read/30296072/antifungal-polyamides-of-hydroxycinnamic-acids-from-sunflower-bee-pollen
#8
Jan Kyselka, Roman Bleha, Miroslav Dragoun, Kristýna Bialasová, Šárka Horáčková, Martin Schatz, Marcela Sluková, Vladimír Filip, A Synytsya
The aim of the bioassay-guided fractionation was the selection of the most potent group of compounds responsible for the protection of sunflower bee pollen grains. Synthesis of prospective antifungal polyamides of hydroxycinnamic acids was based on previous structural elucidation of ethanol soluble fraction by 1H, 1H-PFG-COSY; 1H, 13C-HSQC; FT-IR; FT-Raman and LC-MS experiments. The main compounds found were tri-p-coumaroylspermidines accompanied by other HCAA of spermidine and putrescine. Several model HCAA derivatives were prepared to test their antifungal activity against widespread spoilage fungi (A...
October 8, 2018: Journal of Agricultural and Food Chemistry
https://www.readbyqxmd.com/read/30282935/polysulfone-polyamide-sio%C3%A2-composite-membrane-with-high-permeance-for-organic-solvent-nanofiltration
#9
Qin Liu, Xing Wu, Kaisong Zhang
To improve the filtration performance and properties of organic solvent nanofiltration (OSN) membranes, we firstly introduce nanoporous silica (SiO₂) particles into the polyamide (PA) active layer of polysulfone (PSf) membrane via an interfacial polymerization process. Results from the study revealed that introduction of SiO₂ influenced the properties of PSf/PA-SiO₂ composite membranes by changing the surface roughness and hydrophilicity. Moreover, results also indicated that nanoporous SiO₂ modified membranes showed an improved performance of alcohols solvent permeance...
October 3, 2018: Membranes
https://www.readbyqxmd.com/read/30282331/optimization-of-the-configuration-of-porous-bone-scaffolds-made-of-polyamide-hydroxyapatite-composites-using-selective-laser-sintering-for-tissue-engineering-applications
#10
M Ramu, M Ananthasubramanian, T Kumaresan, R Gandhinathan, Sathiskumar Jothi
Numerous biomaterials are used to fabricate bone scaffolds to repair the bones subjected to trauma. The scaffolds are fabricated with interconnected pores with 40-70% porosity to facilitate the entry of the cells that ensures rapid bone formation. In addition, the interconnected pores also serve as a channel for the exchange of nutrients and waste materials. Rapid prototyping techniques use the CAD model of the scaffold to be fabricated which facilitates fabrication of components with complex architecture easily...
September 26, 2018: Bio-medical Materials and Engineering
https://www.readbyqxmd.com/read/30279477/additive-manufactured-and-topology-optimized-passive-shimming-elements-for-permanent-magnetic-systems
#11
Christian Huber, Michael Goertler, Claas Abert, Florian Bruckner, Martin Groenefeld, Iulian Teliban, Dieter Suess
A method to create a highly homogeneous magnetic field by applying topology optimized, additively manufactured passive shimming elements is investigated. The topology optimization algorithm can calculate a suitable permanent and nonlinear soft magnetic design that fulfills the desired field properties. The permanent magnetic particles are bonded in a polyamide matrix and they are manufactured with a low-cost, end-user 3D printer. Stray field measurements and an inverse stray field simulation framework can determine printing and magnetization errors...
October 2, 2018: Scientific Reports
https://www.readbyqxmd.com/read/30271444/flavone-constituents-of-phlomis-bruguieri-desf-with-cytotoxic-activity-against-mcf-7-breast-cancer-cells
#12
Seyed Ebrahim Sajjadi, Zeinab Delazari, Mahmoud Aghaei, Mustafa Ghannadian
Phlomis bruguieri (P. bruguieri) is a large genus in the Lamiaceae family, with a wide variety distributed in Euro-Asia, Central Asia, Iran, and China. Phlomis flowers have been used as herbal tea for gastrointestinal disturbances, protection of liver and cardiovascular systems. The aim of this study was to analyse phytochemical of flavonoid constituents in semi polar fraction of P. bruguieri . Methanol extract of plant material (4 kg) yielded 361 g dark green concentrated extract gum. After preliminary fractionation by normal column chromatography on silica gel, Fr...
October 2018: Research in Pharmaceutical Sciences
https://www.readbyqxmd.com/read/30268678/mechanical-and-cytotoxicity-properties-of-hybrid-ceramics-filled-polyamide-12-filament-feedstock-for-craniofacial-bone-reconstruction-via-fused-deposition-modelling
#13
Abdul Manaf Abdullah, Tuan Noraihan Azila Tuan Rahim, Wan Nur Fadilla Wan Hamad, Dasmawati Mohamad, Hazizan Md Akil, Zainul Ahmad Rajion
OBJECTIVE: To compare the mechanical and biological properties of newly developed hybrid ceramics filled and unfilled polyamide 12 (PA 12) for craniofacial reconstruction via a fused deposition modelling (FDM) framework. METHODS: 15wt% of zirconia (ZrO2 ) as well as 30, 35, and 40wt% of beta-tricalcium phosphate (β-TCP) were compounded with PA 12, followed by the fabrication of filament feedstocks using a single screw extruder. The fabricated filament feedstocks were used to print the impact specimens...
September 26, 2018: Dental Materials: Official Publication of the Academy of Dental Materials
https://www.readbyqxmd.com/read/30260219/distinguishing-chemically-similar-polyamide-materials-with-tof-sims-using-self-organising-maps-and-a-universal-data-matrix
#14
Robert M T Madiona, Sarah E Bamford, David A Winkler, Benjamin W Muir, Paul J Pigram
Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is advancing rapidly, providing instruments with growing capabilities and resolution. The data sets generated by these instruments are likewise increasing dramatically in size and complexity. Paradoxically, methods for efficient analysis of these large, rich data sets have not improved at the same rate. Clearly, more effective computational methods for analysis of ToF-SIMS data are becoming essential. Several research groups are customising standard multivariate analytical tools to decrease computational demands, provide user-friendly interfaces, and simplify identification of trends and features in large ToF-SIMS data sets...
September 27, 2018: Analytical Chemistry
https://www.readbyqxmd.com/read/30259005/enzymatic-polymerization-of-dimethyl-2-5-furandicarboxylate-and-heteroatom-diamines
#15
Dina Maniar, Katharina F Hohmann, Yi Jiang, Albert J J Woortman, Jur van Dijken, Katja Loos
Previously, we have synthesized a diverse range of 2,5-furandicarboxylic acid (FDCA)-based semiaromatic polyamides via enzymatic polymerization. This novel class of polymers are biobased alternatives to polyphthalamides, which are petrol-based semiaromatic polyamides. From a commercial perspective, they have interesting properties as high-performance materials and engineering thermoplastics. It is even more appealing to explore novel FDCA-based polyamides with added functionality, for the development of sustainable functional materials...
June 30, 2018: ACS Omega
https://www.readbyqxmd.com/read/30258839/multi-layer-filters-adsorption-and-filtration-mechanisms-for-improved-separation
#16
Aysu Onur, Aaron Ng, Warren Batchelor, Gil Garnier
Filters made of cellulose fiber and perlite particles were prepared using a wet laying papermaking technique. Polyamide-amine-epichlorohydrin (PAE) was added to provide wet strength. Filters were prepared at two different total basis weights of 200 and 400 grams per square meter (gsm). Single and multi-layered filters were structured for each total basis weights. The effect of total basis weights and multi-layered structure on methylene blue adsorption and silicon dioxide (SiO2 ) particle filtration was investigated...
2018: Frontiers in Chemistry
https://www.readbyqxmd.com/read/30248828/studies-of-the-effects-of-microplastics-on-aquatic-organisms-what-do-we-know-and-where-should-we-focus-our-efforts-in-the-future
#17
REVIEW
Luís Carlos de Sá, Miguel Oliveira, Francisca Ribeiro, Thiago Lopes Rocha, Martyn Norman Futter
The effects of microplastics (MP) on aquatic organisms are currently the subject of intense research. Here, we provide a critical perspective on published studies of MP ingestion by aquatic biota. We summarize the available research on MP presence, behaviour and effects on aquatic organisms monitored in the field and on laboratory studies of the ecotoxicological consequences of MP ingestion. We consider MP polymer type, shape, size as well as group of organisms studied and type of effect reported. Specifically, we evaluate whether or not the available laboratory studies of MP are representative of the types of MPs found in the environment and whether or not they have reported on relevant groups or organisms...
December 15, 2018: Science of the Total Environment
https://www.readbyqxmd.com/read/30236941/ph-mediated-reversible-fluorescence-nanoswitch-based-on-inner-filter-effect-induced-fluorescence-quenching-for-selective-and-visual-detection-of-4-nitrophenol
#18
Lei Han, Shi Gang Liu, Jia Yu Liang, Yan Jun Ju, Nian Bing Li, Hong Qun Luo
Being a common hazardous waste, 4-nitrophenol (4-NP) has caused a serious threat to humans and environment. Therefore, rapid and selective detection of 4-NP, especially using a simple and portable instrument, is highly desired for human health and environmental monitoring. Herein, we develop a novel pH-mediated reversible fluorescence nanoswitch for selectively detecting 4-NP by using water-soluble fluorescent polymer carbon dots (PCDs) as a probe. The fluorescence of PCDs can be quenched by 4-NP via inner filter effect (IFE) because its excitation spectrum well overlaps with the absorption spectrum of 4-NP under alkaline condition...
January 15, 2019: Journal of Hazardous Materials
https://www.readbyqxmd.com/read/30229325/enhanced-synthesis-of-poly-gamma-glutamic-acid-by-increasing-the-intracellular-reactive-oxygen-species-in-the-bacillus-licheniformis-%C3%AE-1-pyrroline-5-carboxylate-dehydrogenase-gene-ycgn-deficient-strain
#19
Bichan Li, Dongbo Cai, Shiying Hu, Anting Zhu, Zhili He, Shouwen Chen
Poly gamma glutamic acid (γ-PGA) is an anionic polyamide with numerous applications. Previous studies revealed that L-proline metabolism is implicated in a wide range of cellular processes by increasing intercellular reactive oxygen species (ROS) generation. However, the relationship between L-proline metabolism and γ-PGA synthesis has not yet been analyzed. In this study, our results confirmed that deletion of Δ1-pyrroline-5-carboxylate dehydrogenase gene ycgN in Bacillus licheniformis WX-02 increased γ-PGA yield to 13...
September 19, 2018: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/30226794/bench-and-pilot-scale-performance-assessment-of-recycled-membrane-converted-from-old-nanofiltration-membranes
#20
Eduardo Coutinho de Paula, Poliana Vicente Martins, Isabella Coelho de Melo Ferreira, Míriam Cristina Santos Amaral
Recycling of end-of-life polyamide-based thin film composite (TFC) membranes is gaining interest in academic and industrial contexts. The effects of chlorine exposure on the performance of polyamide membranes result in an increase in membrane permeability, whereas the solute rejection decreases. Therefore, the controlled chemical conversion of old reverse osmosis (RO) membranes has been reported by some previous papers. The objectives of this study were to assess recycling of old nanofiltration (NF) membrane, to assess the performance of the recycled membranes for a river water treatment application, and to conduct preliminary cost evaluations...
September 18, 2018: Environmental Technology
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