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https://www.readbyqxmd.com/read/28943716/direct-access-to-functional-meth-acrylate-copolymers-through-transesterification-with-lithium-alkoxides
#1
Carolin Fleischmann, Athina Anastasaki, Will R Gutekunst, Alaina J McGrath, Phillip D Hustad, Paul G Clark, David S Laitar, Craig J Hawker
A straightforward and efficient synthetic method that transforms poly(methyl methacrylate) (PMMA) into value-added materials is presented. Specifically, PMMA is modified by transesterification to produce a variety of functional copolymers from a single starting material. Key to the reaction is the use of lithium alkoxides, prepared by treatment of primary alcohols with LDA, to displace the methyl esters. Under optimized conditions, up to 65% functionalization was achieved and copolymers containing alkyl, alkene, alkyne, benzyl, and (poly)ether side groups could be prepared...
May 1, 2017: Journal of Polymer Science. Part A, Polymer Chemistry
https://www.readbyqxmd.com/read/28940336/unveiling-active-sites-for-the-hydrogen-evolution-reaction-on-monolayer-mos2
#2
Jing Zhang, Jingjie Wu, Hua Guo, Weibing Chen, Jiangtan Yuan, Ulises Martinez, Gautam Gupta, Aditya Mohite, Pulickel M Ajayan, Jun Lou
Here, the hydrogen evolution reaction (HER) activities at the edge and basal-plane sites of monolayer molybdenum disulfide (MoS2 ) synthesized by chemical vapor deposition (CVD) are studied using a local probe method enabled by selected-area lithography. Reaction windows are opened by e-beam lithography at sites of interest on poly(methyl methacrylate) (PMMA)-covered monolayer MoS2 triangles. The HER properties of MoS2 edge sites are obtained by subtraction of the activity of the basal-plane sites from results containing both basal-plane and edge sites...
September 22, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28940164/fabrication-of-nanoscale-pits-with-high-throughput-on-polymer-thin-film-using-afm-tip-based-dynamic-plowing-lithography
#3
Yang He, Yanquan Geng, Yongda Yan, Xichun Luo
We show that an atomic force microscope (AFM) tip-based dynamic plowing lithography (DPL) approach can be used to fabricate nanoscale pits with high throughput. The method relies on scratching with a relatively large speed over a sample surface in tapping mode, which is responsible for the separation distance of adjacent pits. Scratching tests are carried out on a poly(methyl methacrylate) (PMMA) thin film using a diamond-like carbon coating tip. Results show that 100 μm/s is the critical value of the scratching speed...
September 22, 2017: Nanoscale Research Letters
https://www.readbyqxmd.com/read/28937763/hybrid-cis-trans-tetra-arylethenes-with-switchable-aie-and-reversible-photochromism-in-the-solution-pmma-film-solid-powder-and-single-crystal
#4
Qianfu Luo, Fei Cao, Chaochao Xiong, Qingyu Dou, Da-Hui Qu
How to efficiently design and synthesize multifunctional molecules is particularly challenging. Here we devote to constructing a kind of simple structures with composite functionalities through straightforward preparation. Starting from common commercially available materials, the titled cis/ tans-tetraarylethenes can be conveniently obtained by one-pot under mild conditions. The different configurations were confirmed by 1H NMR and single crystal data analysis. The trans-tetraarylethenes could be converted into cis-forms not only by photo-irradiation but also by microwave irradiation, which provided us a new choice for isomeric conversion, especially for which sensitive to light...
September 22, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28936046/a-comparative-study-to-check-fracture-strength-of-provisional-fixed-partial-dentures-made-of-autopolymerizing-polymethylmethacrylate-resin-reinforced-with-different-materials-an-in-vitro-study
#5
Parikshit Gupt, Archana Nagpal, Rupandeep Kaur Samra, Ramit Verma, Jasjeet Kaur, Surbhi Abrol
AIM: The purpose of the study was to evaluate the fracture strength of provisional fixed partial dentures made of autopolymerizing polymethylmethacrylate (PMMA) resin using different types of reinforcement materials to determine the best among them. MATERIALS AND METHODS: Fifty samples were made (10 samples for each group) with autopolymerizing PMMA resin using reinforcement materials (stainless steel wire: looped and unlooped and glass fiber: loose and unidirectional) as 3-unit posterior bridge...
July 2017: Journal of Indian Prosthodontic Society
https://www.readbyqxmd.com/read/28934967/building-a-resistance-to-ignition-testing-device-for-sunglasses-and-analysing-data-a-continuing-study-for-sunglasses-standards
#6
Renan Magri, Mauro Masili, Fernanda Oliveira Duarte, Liliane Ventura
BACKGROUND: Sunglasses popularity skyrocketed since its advent. The ongoing trend led to the creation of standards to protect consumers from injuries and secondary hazards due to spectacles use. In Brazil, the corresponding standard is NBR ISO 12312-1:2015 and since there is no mandatory testing, evaluating sunglasses performance provides an insight into compliance with the standard. In a continuing revision of sunglasses standards requirements, resistance to ignition is one of the concerns, since sunglasses should be protected from burning into flames at a pre-determined temperature, which may protect user of getting their sunglasses into flames if some, cigarette sparks reaches the spectacles, as an example...
September 21, 2017: Biomedical Engineering Online
https://www.readbyqxmd.com/read/28932142/color-stability-and-marginal-integrity-of-interim-crowns-an-in-vitro-study
#7
Marwa I Elagra, Mohammad R Rayyan, Maisam M Alhomaidhi, Areej A Alanaziy, Mona O Alnefaie
OBJECTIVE: Many commercial dental materials are used to fabricate interim restorations. This study aimed to compare the color stability and the marginal integrity of four different interim crown materials. MATERIALS AND METHODS: An ivorine right maxillary central incisor was prepared for a full coverage all-ceramic restoration. A total of 36 specimens in the form of crowns were fabricated on the master die using four different materials (n = 9); Polymethyl methacrylate (PMMA) resin (TrimPLUS), PMMA computer-aided design, and computer-aided manufacturing (CAD-CAM) blocks (Ceramill TEMP), cold cure bis-acryl resin (Success CD), and bis-acryl resin dual-cure composite (TempSpan)...
July 2017: European Journal of Dentistry
https://www.readbyqxmd.com/read/28931340/lessons-learnt-from-early-failure-of-a-patient-trial-with-a-polymer-on-polymer-resurfacing-hip-arthroplasty
#8
Job L C Van Susante, Nico Verdonschot, L Paul A Bom, Pawel Tomaszewski, Pat Campbell, Edward Ebramzadeh, B Wim Schreurs
Background and purpose - Hip resurfacing (HR) is a treatment option promoted for hip arthritis in young and active patients. However, adverse reactions to metal are a concern and the search for non-metallic bearing options proceeds. We present the first clinical study performed in patients using a newly developed hydrophilic polymer-on-polymer hip resurfacing device. Patients and methods - After performing extensive hip simulator tests, biocompatibility testing and animal tests (ISO 14242-1,3; 10993-3,4,5,10,11), approval was obtained from the IRB committee to enroll 15 patients in the first clinical study in humans using this experimental polymer-on-polymer hip resurfacing device...
September 21, 2017: Acta Orthopaedica
https://www.readbyqxmd.com/read/28929736/substrate-versatile-approach-to-robust-antireflective-and-superhydrophobic-coatings-with-excellent-self-cleaning-property-in-varied-environments
#9
Tingting Ren, Junhui He
Robust antireflective and superhydrophobic coatings are highly desired in wide applications, such as optical devices, solar cell panels, architectural and automotive glasses, lab-on chip systems, and windows for electronic devices. Meanwhile, simple, low-cost, and substrate-versatile fabrication is also essential toward real applications of such coatings. Herein, we developed a substrate-versatile strategy to fabricate robust antireflective and superhydrophobic coatings with excellent self-cleaning property in varied environments, including air and oil and after oil contamination...
September 20, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28926275/mapping-photoemission-and-hot-electron-emission-from-plasmonic-nanoantennas
#10
Richard Hobbs, William Putnam, Arya Fallahi, Yujia Yang, Franz Kaertner, Karl K Berggren
Understanding plasmon-mediated electron emission and energy transfer on the nanometer length scale is critical to controlling light-matter interactions at nanoscale dimensions. In a high-resolution lithographic material, electron emission and energy transfer lead to chemical transformations. In this work, we employ such chemical transformations in two different high-resolution electron-beam lithography resists, poly(methyl methacrylate) (PMMA) and hydrogen silsesquioxane (HSQ), to map local electron emission and energy transfer with nanometer resolution from plasmonic nanoantennas excited by femtosecond laser pulses...
September 19, 2017: Nano Letters
https://www.readbyqxmd.com/read/28924625/-course-of-operative-treatment-of-a%C3%A2-sacral-insufficiency-fracture-successful-or-serious-treatment
#11
A Lattauschke, F Klauke, B W Ullrich, G O Hofmann, T Mendel
A monolateral sacrum fracture was primarily diagnosed with a CT and treated with PMMA augmented SI screw fixation. The following CT showed an unexpected contralateral fracture which led to the need for a lumbopelvic stabilization. In the course of 6 months, successively occurring adjacent fractures required recurrent vertebroplasty. Most of these fractures could only be diagnosed through MRI. It remains unclear, whether initially even the contralateral sacral ala was fractured.
September 18, 2017: Der Unfallchirurg
https://www.readbyqxmd.com/read/28921703/poly-vinylidene-fluoride-co-chlorotrifluoroethylene-modification-via-organocatalyzed-atom-transfer-radical-polymerization
#12
Xin Hu, Yajun Zhang, Guopeng Cui, Ning Zhu, Kai Guo
To address the challenge of metal contamination, a "graft from" approach via organocatalyzed atom transfer radical polymerization (O-ATRP) is developed to synthesize poly(vinylidene fluoride-co-chlorotrifluoroethylene) (P(VDF-co-CTFE)) graft copolymers. N-phenylphenothiazine is utilized as a model organic photoredox catalyst for catalyzing the (co)polymerization of methyl methacrylate (MMA), methacrylate (MA), and n-butyl acrylate (BA). By employing this technique, high temporal control of polymerization and graft content are achieved...
September 15, 2017: Macromolecular Rapid Communications
https://www.readbyqxmd.com/read/28915350/the-zeta-potential-of-pmma-in-contact-with-aqueous-electrolyte-surfactant-solutions
#13
Mahmoud Khademi, Wuchun Mike Wang, Wolfgang Reitinger, Dominik Pj Barz
Addition of surfactants can considerably impact the electrical characteristics of an interface and the zeta potential measurement is the standard method for its characterization. In this article, a comprehensive study of the zeta potential of poly(methyl methacrylate) (PMMA) in contact with aqueous solutions containing an anionic, a cationic, or a zwitterionic surfactant at different pH and ionic strength values is conducted. Electrophoretic mobilities are inferred from electrophoretic light scattering measurements of the particulate PMMA...
September 15, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28910324/effect-of-dialyzer-membrane-materials-on-survival-in-chronic-hemodialysis-patients-results-from-the-annual-survey-of-the-japanese-nationwide-dialysis-registry
#14
Masanori Abe, Takayuki Hamano, Atsushi Wada, Shigeru Nakai, Ikuto Masakane
BACKGROUND: Little information is available regarding which type of dialyzer membrane results in good prognosis in patients on chronic hemodialysis. Therefore, we conducted a cohort study from a nationwide registry of hemodialysis patients in Japan to establish the association between different dialyzer membranes and mortality rates. METHODS: We followed 142,412 patients on maintenance hemodialysis (female, 39.1%; mean age, 64.8 ± 12.3 years; median dialysis duration, 7 [4-12] years) for a year from 2008 to 2009...
2017: PloS One
https://www.readbyqxmd.com/read/28901356/cyclometalated-pt-ii-complexes-with-a-bidentate-schiff-base-ligand-displaying-unexpected-cis-trans-isomerism-synthesis-structures-and-electronic-properties
#15
A Poma, A Forni, C Baldoli, P R Mussini, A Bossi
Square planar platinum complexes are an important class of compounds used in (nano)technology, optoelectronics, medicinal chemistry and catalysis. The major research interests in cyclometalated Pt(ii) complexes focus on the selective modulation of their electronic properties and the control of the (cis/trans) geometry. For the first time, we unveil and demonstrate that cis-trans isomers of Pt(ii) complexes can be obtained in a derivative carrying the 1-phenyl-pirazolate (Hppz) and 2-hydroxy-1-naphtyl-(N-phenyl)imine ligands...
September 26, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28895738/tailoring-ink-substrate-interactions-via-thin-polymeric-layers-for-high-resolution-printing
#16
Aleksander Matavž, Vid Bobnar, Barbara Malic
The surface properties of a substrate are among the most important parameters in the printing technology of functional materials, determining not only the printing resolution but also the stability of the printed features. This paper addresses the wetting difficulties encountered during inkjet printing on homogeneous substrates as a result of improper surface properties. We show that the wetting of a substrate and, consequently, the quality of the printed pattern, can be mediated through the deposition of polymeric layers that are a few nanometers thick...
September 12, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28895722/dielectric-sphere-clusters-as-a-model-to-understand-infrared-spectroscopic-imaging-data-recorded-from-complex-samples
#17
Ilia L Rasskazov, Nicolas Spegazzini, P Scott Carney, Rohit Bhargava
Understanding the infrared (IR) spectral response of materials as a function of their morphology is not only of fundamental importance but also of contemporary practical need in the analysis of biological and synthetic materials. While significant work has recently been reported in understanding the spectra of particles with well-defined geometries, we report here on samples that consist of collections of particles. First, we theoretically model the importance of multiple scattering effects and computationally predict the impact of local particles' environment on the recorded IR spectra...
September 12, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28895558/combination-photo-and-electron-beam-lithography-with-polymethyl-methacrylate-pmma-resist
#18
Daniel J Carbaugh, Sneha G Pandya, Jason T Wright, Savas Kaya, Faiz Rahman
We describe techniques for performing photolithography and electron beam lithography in succession on the same resist-covered substrate. Larger openings are defined in the resist film through photolithography whereas smaller openings are defined through conventional electron beam lithography. The two processes are carried out one after the other and without an intermediate wet development step. At the conclusion of the two exposures, the resist film is developed once to reveal both large and small openings...
September 12, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28894533/the-residual-monomer-content-and-mechanical-properties-of-cad-cam-resins-used-in-the-fabrication-of-complete-dentures-as-compared-to-heat-cured-resins
#19
Al-Dharrab Ayman
BACKGROUND: The utilization of computer-assisted designing and computer-assisted milling CAD\CAM resins in the fabrication of removable prostheses is a modern-day concept that offers many advantages over the use of the traditional polymethylmethacrylate (PMMA). AIM: This study instigated some of the mechanical properties of CAD\CAM denture base resin including the amount of residual monomer. METHODS: This study was conducted at the Faculty of Dentistry, King Abdulaziz University from October 2016 to February 2017...
July 2017: Electronic Physician
https://www.readbyqxmd.com/read/28887680/cervical-vertebroplasty-under-sedoanalgesia-using-combined-ultrasonography-and-fluoroscopy-guidance-a-novel-technique
#20
Serbülent Gökhan Beyaz, Havva Sayhan, Mustafa Erkan İnanmaz, Mustafa Orhan
PURPOSE: The aim of this report was to describe a case using combined USG and fluoroscopy for cervical VP via a percutaneous route under sedoanalgesia. METHODS: A 70-year-old male patient had severe neck pain for 6 weeks because of metastatic mass lesions in C6. After the decision to VP, the patient was placed on the operating table and 2 mg midazolam and 75 µg fentanyl were administered for conscious sedation. Localisation of the carotid artery, internal jugular vein, and trachea had been determined with USG...
September 8, 2017: European Spine Journal
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