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Danny Omar Mendoza Marin, Andressa Rosa Perin Leite, Norberto Martins de Oliveira Junior, André Gustavo Paleari, Ana Carolina Pero, Marco Antonio Compagnoni
Several attachment systems for mandibular implant-supported overdentures are currently available and studies are required to understand their mechanical properties. The objective of this study was to evaluate the retention force and wear characteristics of three attachment systems in a simulation of the cyclic dislodging of implant-supported overdentures. Thirty samples were fabricated and divided into 3 groups: 1-O-ring; 2-Mini Ball; and 3-Equator. A mechanical fatigue test was applied to the specimens using a servo-hydraulic universal testing machine performing 5500 insertion/removal cycles (f=0...
November 2018: Brazilian Dental Journal
Xuechen Zhou, Yang-Ying Zhao, Sang-Ryoung Kim, Menachem Elimelech, Shu Hu, Jae-Hong Kim
Enhancing the chemical and physical properties of the polyamide active layer of thin-film composite (TFC) membranes by surface coating is a goal long-pursued. Atomic layer deposition (ALD) has been proposed as an innovative approach to deposit chemically robust metal oxides onto membrane surfaces due to its unique capability to control coating conformality and thickness with atomic scale precision. This study examined the potential to coat the surface of TFC reverse osmosis (RO) and nanofiltration (NF) membranes via ALD of TiO2 ...
December 5, 2018: Environmental Science & Technology
Jun Wang, Zhao-Li Mou, Hui-Ling Duan, Shi-Yao Ma, Jing Zhang, Zhi-Qi Zhang
Magnetic hyperbranched polyamide amine (MHPA) was successfully prepared and applied as a QuEChERS adsorbent to the gas chromatograph-mass spectrometer (GC-MS) detection of organophosphorus pesticides (OPPs) in orange juice. Abundant in amino types and the structure of hyperbranched organic chains make MHPA to possess the clean-up function integrating classic clean-up agent primary secondary amine (PSA) with C18 modified silica, and the magnetic property makes the operation easier and more time-saving. Compared the performance with classical clean-up agents of PSA and C18 , better results were obtained with MHPA as adsorbent for the detection of 11 OPPs...
November 27, 2018: Journal of Chromatography. A
Werner Schlemmer, Armin Zankel, Katrin Niegelhell, Mathias Hobisch, Michael Süssenbacher, Krisztina Zajki-Zechmeister, Michael Weissl, David Reishofer, Harald Plank, Stefan Spirk
This study investigates flexible (polyamide 6.6 PA-6.6, polyethylene terephthalate PET, Cu, Al, and Ni foils) and, for comparison, stiff substrates (silicon wafers and glass) differing in, for example, in surface free energy and surface roughness and their ability to host cellulose-based thin films. Trimethylsilyl cellulose (TMSC), a hydrophobic acid-labile cellulose derivative, was deposited on these substrates and subjected to spin coating. For all the synthetic polymer and metal substrates, rather homogenous films were obtained, where the thickness and the roughness of the films correlated with the substrate roughness and its surface free energy...
November 30, 2018: Materials
Mark Kalaj, Michael Denny, Kyle Bentz, Joseph Palomba, Seth Mason Cohen
Hybridization of metal-organic frameworks (MOFs) and polymers into composites yields materials that display the exceptional properties of MOFs with the robustness of polymers. However, realization of MOF-polymer composites requires efficient dispersion and interactions of MOF particles with polymer matrices, which remains a significant challenge. Herein, we report a simple, scalable, bench-top approach to covalently tethered nylon-MOF polymer composite materials by an interfacial polymerization technique. The copolymerization of a modified UiO-66-NH2 MOF with a growing polyamide fiber (PA-66) during an interfacial polymerization gave hybrid materials with up to ~29 weight percent MOF...
December 3, 2018: Angewandte Chemie
Francesco Saliu, Simone Montano, Maria Grazia Garavaglia, Marina Lasagni, Davide Seveso, Paolo Galli
Microplastics are recognized as a growing threat for the marine environment that may even affect areas generally considered pristine. In this work we surveyed the microplastic contamination in the Faafu Atoll (Maldives, Indian Ocean) across twelve sampling station, located either inside or outside the reef rim. Sediments and seawater samples were collected. Despite the remoteness of the atoll, the scarce local population and low touristic annual afflux, the detected average abundance were 0.32 ± 0.15 particles/m3 in the surface water and 22...
November 2018: Marine Pollution Bulletin
Ryan Andrades, Robson G Santos, Jean-Christophe Joyeux, David Chelazzi, Alessandra Cincinelli, Tommaso Giarrizzo
Marine debris is widespread in oceans worldwide, including the most remote locations. Here, for the first time, we report macro-debris accumulation on beaches of Trindade Island, a remote island 1160 km from mainland Brazil. High debris density was recorded on windward, east-coast beaches, which are exposed to wind-driven currents. Small-sized plastic fragments were the most abundant debris. Polyethylene (67%), polypropylene (30%) and polyamide (3%) were the most prevalent polymeric materials identified by ATR-FTIR...
December 2018: Marine Pollution Bulletin
Maria Chiara Mistretta, Marco Morreale, Luigi Botta, Manuela Ceraulo, Paolo Fontana, Francesco Paolo La Mantia
Polyamide/polyolefin blends have gained attention from the academia and the industry for several years. However, in order to optimize their properties, some drawbacks such as chemical incompatibility must be adequately overcome. This can be done by adding suitable compatibilizers. On the other hand, it is less known that suitable processing techniques may also lead to significant results. In a previous work on a low-density polyethylene/polyamide 6 (LDPE/PA6) blend, we found that the orientation due to elongational flow processing conditions could lead to an unexpected brittle⁻ductile transition...
November 26, 2018: Materials
Hyun Ju Song, Yoonjee Chang, Ji Sou Lyu, Mi Yong Yon, Haeng-Shin Lee, Se-Jong Park, Jae Chun Choi, MeeKyung Kim, Jaejoon Han
Caprolactam, used in manufacturing polyamide (PA) 6, may threaten human health. Here, PA 6 sheets were produced by using a twin-screw extruder to evaluate its safety. Caprolactam migration concentrations from the PA 6 sheets into food simulants were evaluated according to the standard migration test conditions under the Korean Food Standards Codex (KFSC). Concentrations were investigated under various food simulants (distilled water, 4% acetic acid, 20 and 50% ethanol, and heptane) and storage conditions (at 25, 60, and 95 °C)...
December 2018: Food Science and Biotechnology
Bowen Hu, Linnan Wang, Yueming Song, Yujie Hu, Qiunan Lyu, Limin Liu, Ce Zhu, Chunguang Zhou, Xi Yang
OBJECTIVES: The nanohydroxyapatite/polyamide-66 (n-HA/PA66) cage is a novel biomimetic nonmetal cage device that is now used in some medical centers, while the titanium mesh cage (TMC) is a typical metal cage device that has been widely used for decades. This study was performed to compare the long-term outcomes of these two different cages in patients undergoing anterior cervical corpectomy. PATIENTS AND METHODS: This retrospective study involved 107 patients who underwent single-level anterior corpectomy using either a TMC (n = 52) or an n-HA/PA66 cage (n = 55) for treatment of cervical degenerative disease with a minimum follow-up of 8 years...
November 19, 2018: Clinical Neurology and Neurosurgery
Yang Song, Jacquelyn Niederschulte, Kristin N Bales, James K Bashkin, Cynthia M Dupureur
PA1: (dIm-PyPyβPyPyPy-γ-PyPyβPyPyPyPyβ-Ta) is a large (14-ring) hairpin polyamide that was designed to recognize the DNA sequence 5'-W2 GW7 -3', where W is either A or T. As is common among the smaller 6-8-ring hairpin PAs, it binds its target recognition sequence with low nM affinity. However, in addition to its large size, it is distinct from these more extensively characterized in its high tolerance for mismatches and antiviral properties. In ongoing attempts to understand the basis for these distinctions, we conducted thermodynamics studies of PA1-DNA interactions...
November 24, 2018: Biochimie
Ke Li, Lifen Liu, Hao Wu, Shanlong Li, Chunyang Yu, Yongfeng Zhou, Wei Huang, Deyue Yan
The structures and transport dynamics of water and salt ions in polyamide (PA) reverse osmosis (RO) membranes as well as the temperature effects on the RO process were systematically investigated using a fully atomistic simulation method. By comparing the experimental data of the commercial membrane FT-30 and the available MD simulation results, the reliability of our PA RO model was validated. In addition, the groups on the polymer chains that preferentially participated in the coordination shells of salt ions were determined...
November 27, 2018: Physical Chemistry Chemical Physics: PCCP
Sang Hee Park, Yeojin Kim, Soon Jin Kwon, Min Gyu Shin, Seung Eun Nam, Young Hoon Cho, You In Park, Jeong F Kim, Jung-Hyun Lee
Organic solvent nanofiltration (OSN) has made significant advances recently, and it is now possible to fabricate thin film composite (TFC) membranes with a selective layer thickness below 10 nm that gives ultrafast solvent permeance. However, such high permeance is inadvertently limited by the support membrane beneath the selective layer, and thus there is an urgent need to develop a suitable support to maximize TFC performance. In this work, we employed a commercially available polyethylene (PE) battery separator as a porous support to fabricate high performance TFC OSN membranes...
November 21, 2018: ACS Applied Materials & Interfaces
Muting Yan, Huayue Nie, Kaihang Xu, Yuhui He, Yingtong Hu, Yumei Huang, Jun Wang
Like many urban rivers, the Pearl River in China is contaminated with microplastics. Compared with marine environments, microplastic pollution in freshwater is less understood, especially in urban rivers. In the present study, the abundance and distribution of microplastics in water from the Pearl River was investigated, including the estuary and the urban section along Guangzhou. The average abundance of microplastics was 19,860 items/m3 and 8902 items/m3 in the urban section and estuary, respectively. Wastewater effluents from cities might be a main source of microplastics in the Pearl River, and the urban tributaries might act as retention systems for microplastics...
November 14, 2018: Chemosphere
Heeseok Lee, Changpyo Han, Hyeok-Won Lee, Gyuyeon Park, Wooyoung Jeon, Jungoh Ahn, Hongweon Lee
Background: As a sustainable industrial process, the production of dicarboxylic acids (DCAs), used as precursors of polyamides, polyesters, perfumes, plasticizers, lubricants, and adhesives, from vegetable oil has continuously garnered interest. Although the yeast Candida tropicalis has been used as a host for DCA production, additional strains are continually investigated to meet productivity thresholds and industrial needs. In this regard, the yeast Wickerhamiella sorbophila , a potential candidate strain, has been screened...
2018: Biotechnology for Biofuels
Pankaj Tripathi, Sumit Singh Phukela, Bhupender Yadav, Puja Malhotra
Background: Denture hygiene is of utmost importance to maintain the dentures as well as the underlying tissues in appropriate health. Various denture cleansers as well as denture-based materials have evolved in the market; however, the effect of denture cleansers on different types of denture-based materials has not been very well documented. Aim: The purpose of this in vitro study was to evaluate and compare the surface roughness in heat-cured denture-based resin and injection-molded resin system as affected by two commercially available denture cleansers for a period of 15, 30, and 45 days...
October 2018: Journal of Indian Prosthodontic Society
Seong-Il Kwon, Geunwoong Ryu, Sungchul Kang, Keri Kim
In this paper, we described the development of an endoscopic system with the application of minimally invasive observation for a pituitary tumor or a craniopharyngioma. The end-effector was manufactured by attaching an image sensor to the end of a manipulator with a diameter of 3 mm (smaller than a commercial endoscope) by making slits on a biocompatible PAI (Polyamide-imide) tube. The end-effector having 2 degrees of freedom for bending is designed not only to cover most of the FOVs (92.8% of the goal) with commercially available fixed-angle endoscopes at 0, 30, and 70 degrees, but also to be able to maneuver the endoscope intuitively...
July 2018: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Patina K Mendez, Sangyeon Lee, Chris E Venter
Availability of 3D-printed laboratory equipment holds promise to improve arthropod digitization efforts. A 3D-printed specimen scanning box was designed to image fluid-based arthropod collections using a consumer-grade flatbed scanner. The design was customized to accommodate double-width microscope slides and printed in both Polylactic Acid (PLA) and nylon (Polyamide). The workflow with two or three technicians imaged Trichoptera lots in batches of six scanning boxes. Individual images were cropped from batch imagess using an R script...
2018: ZooKeys
Jianliang Zhao, Zhenzhen Dong, Hanrui Cui, Hongwei Jin, Caiqi Wang
Facing the global health crisis caused by drug-resistant bacteria, antimicrobial peptides and their analogues offer exciting solutions to this widespread problem. Without additionally introducing a fluorescent probe, novel nanoengineered peptide-grafted hyperbranched polymers (NPGHPs) are constructed for their combined outstanding antimicrobial activity and sensitive bacterial detection in real time. Hyperbranched polyamide amine (H-PAMAM) that exhibits aggregation-induced emission (AIE) effects is synthesized...
November 27, 2018: ACS Applied Materials & Interfaces
Bingbing Yuan, Chi Jiang, Pengfei Li, Honghong Sun, Peng Li, Tao Yuan, Haixiang Sun, Qingshan Jason Niu
Poly(piperazine-amide)-based nanofiltration membranes exhibit a smooth surface and superior antifouling properties, but often have lower Ca2+ and Mg2+ rejection due to their larger inner micropore, and thus cannot be extensively used in water softening applications. To decrease the pore size of poly(piperazine-amide) membranes, we designed and synthesized a novel monomer, 1,2,3,4-cyclobutane tetracarboxylic acid chloride (BTC), which possesses a smaller molecular conformation than trimesoyl chloride (TMC). The thickness of the prepared BTC-piperazine (PIP) polyamide nanofilm via interfacial polymerization is as thin as 15 nm, significantly lower than the 50 nm thickness of the TMC-PIP nanofilm...
November 12, 2018: ACS Applied Materials & Interfaces
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