Academic literature on the topic 'Silane reduction method'
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Journal articles on the topic "Silane reduction method"
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Zhang, Peng, Tie Jun Zhao, F. H. Wittmann, and Shao Chun Li. "Preparation and Characteristics of Integral Water Repellent Cement-Based Materials." Materials Science Forum 675-677 (February 2011): 1189–92. http://dx.doi.org/10.4028/www.scientific.net/msf.675-677.1189.
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Polymers are often applied in concrete for multiple purposes and aims. For instance, surface impregnation of concrete with silanes is a reliable technology to protect cement-based materials from ingress of aggressive solutions into the materials. An alternative method is to add silane emulsion into fresh concrete or mortar to produce integral water repellent materials. In this contribution integral water repellent concrete was prepared by adding 1 %, 2 %, 3 %, 4 % and 6 % of silane emulsion. The influence of silane emulsion on the compressive strength, porosity and pore size distribution, water capillary suction and chloride penetration have been investigated. The results indicate that addition of silane emulsion moderately reduced compressive strength of concrete. With 3 % of silane emulsion the reduction is about 10 %. The addition of silane emulsion hardly has influence on pore size distribution. Silane does not block the capillary pores, but only forms a hydrophobic film on the walls of capillary pores. Addition of silane emulsion reduces water capillary suction significantly. The reduction rate is higher than 89 %. Even the surface of integral water repellent concrete is abraded off 7 mm, the material still demonstrates high water repellency because the entire volume is hydrophobic. In addition, chloride penetration also can be reduced substantially.
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Fernandes, Ana C., and Carlos C. Romão. "A novel method for the reduction of imines using the system silane/MoO2Cl2." Tetrahedron Letters 46, no. 51 (December 2005): 8881–83. http://dx.doi.org/10.1016/j.tetlet.2005.10.076.
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Lee, Jea Uk, and Jin-Yong Hong. "Comparison of Surface Modification Methods for Improving the Compatibility of Recycled Plastic Film-Based Aggregates." Polymers 13, no. 22 (November 16, 2021): 3956. http://dx.doi.org/10.3390/polym13223956.
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The surface modification of recycled plastic film-based aggregates was investigated to improve the compatibility between the aggregates and a cement paste. Surface modification was performed using ultraviolet–ozone treatment (UV-O3), a silane coupling agent, O2 atmospheric pressure plasma, and acrylic binder coating methods. The surface properties of the modified aggregates were analyzed using a contact angle measuring instrument. The results revealed that for all surface modification methods, the contact angle decreased with an increase in the treatment time. According to the comparative evaluation results of the changes in the surface characteristics of the aggregates through various surface modification methods, the contact angle reduction rates were 58.9%, 51.4%, 25.5%, and 24.5% for the O2 atmospheric pressure plasma, the acrylic binder coating, the silane coupling agent, and the UV-O3 method, respectively. After 48 h, the contact angle had increased by 110.9%, 29.9%, 16.4%, and 5.9% for the O2 atmospheric pressure plasma, UV-O3, the silane coupling agent, and the acrylic binder coating, respectively. Namely, the surface modification using the acrylic binder coating method was found to be the most effective method in terms of the wettability increase effect and the long-term storage stability.
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Das, Rupali, and R. K. Soni. "Synthesis and surface-enhanced Raman scattering of indium nanotriangles and nanowires." RSC Advances 7, no. 51 (2017): 32255–63. http://dx.doi.org/10.1039/c7ra03317f.
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Indium nano-wires and -triangles are synthesizedviaa modified polyol reduction method and self-assembled on silane treated glass coverslips as SERS substrates, giving large Raman signal enhancement from adsorbed tryptophan molecules under non-resonant excitation at 632.8 nm.
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Stojanovic, Dusica, Goran Vukovic, Aleksandar Orlovic, Petar Uskokovic, Radoslav Aleksic, Natasa Bibic, and Miroslav Dramicanin. "Dispersion and deagglomerat1on of nano-SiO2 particles with a silane modification reagent in supercritical CO2." Chemical Industry 61, no. 3 (2007): 109–16. http://dx.doi.org/10.2298/hemind0703109s.
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The supercritical CO2 method was used in order to perform deagglomeration and improve the dispersion of nano-SiO2 particles. ?-Met-hacryloxypropyltrimethoxysilane was used as the surface modification reagent. The conventional method for coating nano-SiO2 particles was used as the comparison method. Considerable improvement of the dispersion and deagglomeration was found using supercritical CO2. Analysis of the TEM micrographs and DLS results showed the reduction of the average size of the agglomerates with the silane coupling reagent. Thermogravimetric analysis (TGA) showed that the particles treated in super?critical CO2 were more thermally stable than particles treated by conventional method. Encapsulation of several particles coated with the silane coupling reagent was observed in certain parts of the primary particles. A chemical reaction takes place between the modification reagent, MEMO silane, and active hydroxyl groups on the surface of the nano-SiO2 particles. A larger quantity of MEMO silane reacted using the con?ventional method instead of the supercritical method. On the other hand, the reacted silane molecules were better arranged around the particle surface in the supercritical method because of the formation of covalent or self-assembled structures. Polycondensed structures were preferentially obtained in the conventional method. This was achieved by using supercritical CO2, which has a high solvating power such as organic solvents and physical properties (low viscosity, low surface tension and high diffusion coefficient) similar to gases on the other side. These properties enable the sufficient and uniform wettability of nano-SiO2 particle surfaces. These results are important for obtaining nanofillers with improved dispersion and polymer wettability. Such nanofillers can be used to obtain composite materials with considerably improved mechanical characteristics.
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de Noronha, Rita G., Carlos C. Romão, and Ana C. Fernandes. "A novel method for the reduction of alkenes using the system silane/oxo-rhenium complexes." Tetrahedron Letters 51, no. 7 (February 2010): 1048–51. http://dx.doi.org/10.1016/j.tetlet.2009.12.061.
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Wang, Xiao Li, Bo Zhang, Yang Zhao, Yi Xu, and Bin Shi Xu. "Dispersion and Behavior of Silane Coupling Agent to Surface Modification of n-Cu Particles." Advanced Materials Research 92 (January 2010): 73–78. http://dx.doi.org/10.4028/www.scientific.net/amr.92.73.
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The prepared n-Cu particles with the particle size about 20 nm by KBH4 reduction method in aqueous solution was surface modified using silane coupling agent. The surface modification mechanics was researched. The tribological performances of n-Cu particles were tested by friction wear test machine. The results show that the modified n-Cu paritcles by silane coupling agent have high purity, good dispersion performances and wonderful surface activity. In friction process, the modified n-Cu particles can form a layer of organic-inorganic compound film with synergistic effect on worn surface, which improves the tribological performances of friction material.
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Aujara, Kabiru Musa, Buong Woei Chieng, Nor Azowa Ibrahim, Norhazlin Zainuddin, and Chantara Thevy Ratnam. "Gamma-Irradiation Induced Functionalization of Graphene Oxide with Organosilanes." International Journal of Molecular Sciences 20, no. 8 (April 18, 2019): 1910. http://dx.doi.org/10.3390/ijms20081910.
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Gamma-ray radiation was used as a clean and easy method for turning the physicochemical properties of graphene oxide (GO) in this study. Silane functionalized-GO were synthesized by chemically grafting 3-aminopropyltriethoxysilane (APTES) and 3-glycidyloxypropyltrimethoxysilane (GPTES) onto GO surface using gamma-ray irradiation. This established non-contact process is used to create a reductive medium which is deemed simpler, purer and less harmful compared conventional chemical reduction. The resulting functionalized-GO were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), thermogravimetric analysis (TGA), and Raman spectroscopy. The chemical interaction of silane with the GO surface was confirmed by FT-IR. X-ray diffraction reveals the change in the crystalline phases was due to surface functionalization. Surface defects of the GO due to the introduction of silane mioties was revealed by Raman spectroscopy. Thermogravimetric analysis of the functionalized-GO exhibits a multiple peaks in the temperature range of 200–650 °C which corresponds to the degradation of chemically grafted silane on the GO surface.
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Fernandes, Ana C., and Carlos C. Romão. "A novel method for the reduction of sulfoxides and pyridine N-oxides with the system silane/MoO2Cl2." Tetrahedron 62, no. 41 (October 2006): 9650–54. http://dx.doi.org/10.1016/j.tet.2006.07.077.
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de Noronha, Rita G., Carlos C. Romao, and Ana C. Fernandes. "ChemInform Abstract: A Novel Method for the Reduction of Alkenes Using the System Silane/Oxo-Rhenium Complexes." ChemInform 41, no. 22 (June 1, 2010): no. http://dx.doi.org/10.1002/chin.201022034.
Full textDissertations / Theses on the topic "Silane reduction method"
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Parezanovic, Vladimir. "Experimental study of the sensitivity of global properties of turbulent bluff body wakes using steady disturbance methods." Palaiseau, Ecole polytechnique, 2011. https://theses.hal.science/index.php?halsid=uofsba7dj5fa0catc3i9mh00v0&view_this_doc=tel-00670537&version=1.
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La sensibilité des propriétés globales d'un sillage turbulent derrière un cylindre en forme de "D" est étudiée expérimentalement. Un petit cylindre de contrôle (de forme et de diamètre variable) est inséré dans le sillage pour créer une perturbation locale. Un ensemble de mesures basé sur de l'anémométrie à fil chaud et vélocimétrie par images de particules est mis en oeuvre pour obtenir des informations locales et globales du sillage turbulent. Les forces aérodynamiques agissant sur le cylindre principal sont dérivées de mesures de pression autour de son périmètre. Les résultats sont présentés sous la forme de cartes de sensibilité du nombre de Strouhal et la pression de base. La sensibilité des propriétés globales est interprétée par la capacité de la perturbation locale à changer la taille de la région de formation de l'allée de Kármán en agissant principalement sur les propriétés turbulentes de la couche de mélange perturbée. Les mécanismes physiques correspondants sont discutés pour interpréter les origines de réduction de traînée et la modification de fréquence globale. L'impact de la perturbation sur les propriétés 3D du sillage est examiné par corrélation de vitesse à deux points et visualisation. Les configurations bi-stable de l'écoulement pour certaines positions du cylindre de contrôle sont étudiéesThe sensitivity of the global properties of a turbulent wake behind a D-shaped bluff cylinder is investigated experimentally by introducing a much smaller control cylinder of various shapes and diameters as a local disturbance. Hot-wire anemometry and particle image velocimetry are used to obtain local and global measurements of the turbulent wake. Aerodynamic forces acting on the main cylinder are derived from pressure measurements around its perimeter. The results are presented in the form of sensitivity maps of the Strouhal number and base pressure. The sensitivity of global properties is interpreted on the basis of the ability of the control cylinder to change the size of the formation region of the Kármán vortex street mainly through the turbulent properties modification of the perturbed detached shear layer. The corresponding physical mechanisms are discussed with regard to the origins of drag reduction and global frequency modification. The impact of the perturbation on the 3D properties of the wake is investigated through two-point velocity correlation and wake visualization. Bi-stable flow configurations for some positions of the control cylinder are examined
Book chapters on the topic "Silane reduction method"
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Taber, Douglass F. "Functional Group Oxidation and Reduction." In Organic Synthesis. Oxford University Press, 2015. http://dx.doi.org/10.1093/oso/9780190200794.003.0008.
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Debabrata Maiti of the Indian Institute of Technology Bombay found (Chem. Commun. 2012, 48, 4253) that the relatively inexpensive Pd(OAc)2 effectively catalyzed the decarbonylation of an aldehyde 1 to the hydrocarbon 2. Hui Lou of Zhejiang University used (Adv. Synth. Catal. 2011, 353, 2577) a Mo catalyst to effect reduction of the ester 3 to the hydrocarbon 4, with retention of all the skeletal carbons. Jon T. Njardarson of the University of Arizona showed (Chem. Commun. 2012, 48, 7844) that the allylic ether 5 could be reduced with high regioselectivity to give 6. José Barluenga and Carlos Valdés of the Universidad de Oviedo effected (Angew. Chem. Int. Ed. 2012, 51, 5950) the direct conversion of a ketone 7 to the azide 8. Although no cyclic ketones were included in the examples, there is a good chance that this will be the long-sought diastereoselective reduction of a cyclohexanone to the equatorial amine. Hideo Nagashima of Kyushu University reduced (Chem. Lett. 2012, 41, 229) the acid 9 directly to the aldehyde 1 using a ruthenium catalyst with the bis silane 10. Georgii I. Nikonov of Brock University described (Adv. Synth. Catal. 2012, 354, 607) a similar Ru-mediated silane reduction of an acid chloride to the aldehyde. Professor Nagashima used (Angew. Chem. Int. Ed. 2012, 51, 5363) his same Ru catalyst to reduce the ester 11 to the protected amine 12. Shmaryahu Hoz of Bar-Ilan University used (J. Org. Chem. 2012, 77, 4029) photostimulation to promote the SmI2-mediated reduction of a nitrile 13 to the amine 14. Bakthan Singaram of the University of California, Santa Cruz effected (J. Org. Chem. 2012, 77, 221) the same transformation with InCl3/NaBH4. David J. Procter of the University of Manchester described (J. Org. Chem. 2012, 77, 3049) what promises to be a general method for activating Sm metal to form SmI2. Mark T. Hamann of the University of Mississippi directly reduced (J. Org. Chem. 2012, 77, 4578) the nitro group of 15 to the alkylated amine 16. Cleanly oxidizing aromatic methyl groups to the level of the aldehyde without overoxidation has been a challenge.
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Taber, Douglass. "Enantioselective Assembly of Alkylated Stereogenic Centers." In Organic Synthesis. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780199764549.003.0037.
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Oxygenated secondary stereogenic centers are readily available. There is a limited range of carbon nucleophiles that will displace a secondary leaving group in high yield with clean inversion. Teruaki Mukaiyama of the Kitasato Institute has described (Chem. Lett. 2007, 36, 2) an elegant addition to this list. Phosphinites such as 1 are easily prepared from the corresponding alcohols. Quinone oxidation in the presence of a nucleophile led via efficient displacement to the coupled product 2. The sulfone could be reduced with SmI2 to give 3. Enantioselective reduction of trisubstituted alkenes is also a powerful method for establishing alkylated stereogenic centers. Juan C. Carretero of the Universidad Autonoma de Madrid has found (Angew. Chem. Int. Ed. 2007, 46, 3329) that the enantioselective reduction of unsaturated pyridyl sulfones such as 4 was directed by the sulfone, so the other geometric isomer of 4 gave the opposite enantiomer of 5. The protected hydroxy sulfone 5 is a versatile chiral building block. Samuel H. Gellman of the University of Wisconsin has reported (J. Am. Chem. Soc. 2007, 129, 6050) an improved procedure for the aminomethylation of aldehydes. L-Proline-catalyzed condensation with the matched α-methyl benzylamine derivavative 7 gave the aldehyde, which was immediately reduced to the alcohol 8 to avoid racemization. The amino alcohol 8 was easily separated in diastereomerically-pure form. In the past, aldehydes have been efficiently α-alkylated using two-electron chemistry. David W. C. Macmillan of Princeton University has developed (Science 2007, 316, 582; J. Am. Chem. Soc. 2007, 129, 7004) a one-electron alternative. The organocatalyst 9 formed an imine with the aldehyde. One-electron oxidation led to an α-radical, which was trapped by the allyl silane (or, not pictured, a silyl enol ether) leading to the α-alkylated aldehyde 10. This is mechnistically related to the work reported independently by Mukund P. Sibi (J. Am. Chem. Soc. 2007, 129, 4124; OHL Feb. 11, 2008) on one-electron α-oxygenation of aldehydes. Secondary alkylated centers can also be prepared by SN2’ alkylation of prochiral substrates such as 11. Ben L. Feringa of the University of Groningen has shown (J. Org. Chem. 2007, 72, 2558) that the displacement proceeded with high ee even with conventional Grignard reagents.
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Taber, Douglass F. "Best Synthetic Methods: Oxidation and Reduction." In Organic Synthesis. Oxford University Press, 2013. http://dx.doi.org/10.1093/oso/9780199965724.003.0010.
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Johannes G. de Vries of DSM Pharmaceuticals prepared (Chem. Commun. 2009, 3747) Fe nanoparticles that selectively mediated the hydrogenation of Z alkenes and not trisubstituted alkenes. This should allow the conversion of 1 to 2. In the course of a synthesis (Tetrahedron Lett. 2009, 50, 4368) of centrolobine, Teck-Peng Loh of Nanyang Technological University employed an elegant protocol for the reduction of the secondary bromide 3. István Markó of the Université catholique de Louvain observed (Tetrahedron 2009, 65, 10930) that toluates such as 5 can be reduced smoothly with SmI2 to the corresponding C-H. Dan Yang of the University of Hong Kong devised (Organic Lett. 2009, 11, 3302) a triethylsilane-based procedure for the reductive amination of aldehydes and ketones such as 7. Jon A. Tunge of the University of Kansas developed (J. Am. Chem. Soc. 2009, 131, 16626) a complementary protocol for the conversion of an aldehyde or ketone to the protected amine 12. Mark T. Hamann of the University of Mississippi established (Tetrahedron Lett. 2009, 50, 3901) that a nitroaromatic 13 could be reduced in the presence of an acid chloride 14 to deliver the amide 15 directly. Matthias Beller of the Universität Rostock (Angew. Chem. Int. Ed. 2009, 48, 9507) and Hideo Nagashima of Kyushu University (Angew. Chem. Int. Ed. 2009, 48, 9511; J. Am. Chem. Soc. 2009, 131, 15032) reported parallel investigations of the silane-based reduction of an amide 16 to the amine 17. Xue-Long Hou of the Shanghai Institute of Organic Chemistry demonstrated (Tetrahedron Lett. 2009, 50, 5578) that a terminal alkyne 18 could be oxidized to the α-acetoxy ketone 19. Philippe Renaud of the Universität Bern and Armido Studer of West fälische-Wilhelms-Universität established (Angew. Chem. Int. Ed. 2009, 48, 6037) that both zinc enolates and silyl enol ethers could combine with chlorocatechol borane followed by TEMPO to give the α-oxygenated ketone. Stephen P. Marsden of the University of Leeds devised (Tetrahedron Lett. 2009, 50, 6106) a protocol for oxidizing a primary amine 18 to the benzoxazole 24, which has the oxidation state of the carboxylic acid.
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A. Ikner, Luisa, and Charles P. Gerba. "Antiviral Coatings as Continuously Active Disinfectants." In Disinfection of Viruses [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.101752.
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Antimicrobial surfaces and coatings have been available for many decades and have largely been designed to kill or prevent the growth of bacteria and fungi. Antiviral coatings have become of particular interest more recently during the COVID-19 pandemic as they are designed to act as continuously active disinfectants. The most studied antiviral coatings have been metal-based or are comprised of silane quaternary ammonium formulations. Copper and silver interact directly with proteins and nucleic acids, and influence the production of reactive free radicals. Titanium dioxide acts as a photocatalyst in the presence of water and oxygen to produce free radicals in the presence of UV light or visible light when alloyed with copper or silver. Silane quaternary ammonium formulations can be applied to surfaces using sprays or wipes, and are particularly effective against enveloped viruses. Continuously active disinfectants offer an extra barrier against fomite-mediated transmission of respiratory and enteric viruses to reduce exposure between routine disinfection and cleaning events. To take advantage of this technology, testing methods need to be standardized and the benefits quantified in terms of reduction of virus transmission.
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Taber, Douglass F. "Functional Group Transformation: The Castle Synthesis of Celogentin C." In Organic Synthesis. Oxford University Press, 2013. http://dx.doi.org/10.1093/oso/9780199965724.003.0004.
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Mark Cushman of Purdue University found (J. Org. Chem. 2010, 75, 3507) that a benzylic methyl ether 1 could be converted to the aldehyde 2 by N -bromosuccinimide. Two equivalents of NBS gave the methyl ester. Ning Jiao of Peking University used (Organic Lett. 2010, 12, 2888) NaN3 followed by DDQ to oxidize a benzylic halide 3 to the nitrile 4. Hugues Miel of Almac Sciences oxidized (Tetrahedron Lett. 2010, 51, 3216) the ketone 5 to the nitro derivative 6. The oxidative conversion of the nitro compound 7 to the ketone 8 described (Tetrahedron Lett. 2009, 50, 6389) by Vera L. Patrocinio Pereira of the Universidade Federal do Rio de Janeiro proceeded without epimerization. Sundarababu Baskaran of the Indian Institute of Technology Madras established (Angew. Chem. Int. Ed. 2010, 49, 804) that oxidative cleavage of the benzylidene acetal 9 delivered 10 with high regioselectivity. The intramolecular alkene dihydroxylation of 11 originated (Angew. Chem. Int. Ed. 2010, 49, 4491) by Erik J. Alexanian of the University of North Carolina gave 12 with high diastereocontrol. Ruimao Hua of Tsinghua University took advantage (J. Org. Chem. 2010, 75, 2966) of the H-donor properties of DMF to develop an efficient reduction of the alkyne 13 to the alkyne 14 . Alejandro F. Barrero of the University of Granada developed (J. Am. Chem. Soc. 2010, 132, 254) Ti (III) conditions for the reduction of the allylic alcohol 15 to the terminal alkene 16. Isolated alkenes were stable to these conditions. P. Veeraraghavan Ramachandran, also of Purdue University, effected (Tetrahedron Lett. 2010, 51, 3167) reductive amination of 17 to 18 using the now readily available NH3 - BH3 . Bin Ma and Wen-Cherng Lee of BiogenIdec developed (Tetrahedron Lett. 2010, 51, 385) a simple protocol for the conversion of an acid 19 to the free amine 20. Marc Lemaire of Université Lyons 1 established (Tetrahedron Lett. 2010, 51, 2092) that the silane 22 reduced primary, secondary, and tertiary amides to the aldehydes.
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Lambert, Tristan H. "New Methods for C–N Ring Construction." In Organic Synthesis. Oxford University Press, 2015. http://dx.doi.org/10.1093/oso/9780190200794.003.0055.
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The reduction of pyridines offers an attractive approach to piperidine synthesis, and now Toshimichi Ohmura and Michinori Suginome of Kyoto University have developed (J. Am. Chem. Soc. 2012, 134, 3699) a rhodium-catalyzed hydroboration of pyridines, including the reaction of 1 to produce 3. Timothy J. Donohoe at the University of Oxford has found (Org. Lett. 2011, 13, 2074) that pyridinium silanes 4 undergo intramolecular hydride transfer by treatment with TBAF to produce dihydropyridones (e.g., 5) with good diastereoselectivity. Enantioselective amination of allylic alcohols has proven challenging, but Ross A. Widenhoefer at Duke University has reported (Angew. Chem. Int. Ed. 2012, 51, 1405) that a chiral gold catalyst can effect such intramolecular cyclizations with good enantioselectivity, as in the synthesis of 7 from 6. Alternatively, Masato Kitamura at Nagoya University has developed (Org. Lett. 2012, 14, 608) a ruthenium catalyst that operates at as low as 0.05 mol% loading for the conversion of substrates such as 8 to 9. Efforts to replace transition metal catalysts with alkaline earth metal-based alternatives have been gaining increasing attention, and Kai C. Hultzsch at Rutgers University has found (Angew. Chem. Int. Ed. 2012, 51, 394) that the magnesium complex 12 is capable of catalyzing intramolecular hydroamination (e.g., 10 to 11) with high enantioselectivity. Meanwhile, a stereoselective Wacker-type oxidation of tert-butanesulfinamides such as 13 to produce pyrrolidine derivatives 14 has been disclosed (Org. Lett. 2012, 14, 1242) by Shannon S. Stahl at the University of Wisconsin at Madison. Though highly desirable, Heck reactions have rarely proven feasible with alkyl halides due to competitive β-hydride elimination of the alkyl palladium intermediates. Sherry R. Chemler at the State University of New York at Buffalo has demonstrated (J. Am. Chem. Soc. 2012, 134, 2020) a copper-catalyzed enantioselective amination Heck-type cascade (e.g., 15 and 16 to 17) that is thought to proceed via radical intermediates. David L. Van Vranken at the University of California at Irvine has reported (Org. Lett. 2012, 14, 3233) the carbenylative amination of N-tosylhydrazones, which proceeds through η3-allyl Pd intermediates constructed via carbene insertion. This chemistry was applied to the two-step synthesis of caulophyllumine B from vinyl iodide 18 and N-tosylhydrazone 19.
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Taber, Douglass F. "The Herzon Synthesis of (−)-Acutumine." In Organic Synthesis. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780190646165.003.0085.
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The alkaloid (−)-acutumine 3, isolated from the roots of the Chinese moonseed Sinomenium acutum, improves object and social recognition in the Wistar rat model. With four rings and three adjacent, fully-substituted stereogenic centers, 3 presents a significant synthetic challenge. Seth B. Herzon of Yale University assembled (Angew. Chem. Int. Ed. 2013, 52, 3642) 3 by the intramolecular Sakurai cyclization of 1 to 2. The convergent preparation of 1 required the alkyne 10. The literature construction (Org. Lett. 2005, 7, 5075) by A. B. Smith III of the enone 7 from ribose 4 began with protection to 5. Conversion of the primary alcohol to the iodide followed by reduction delivered the aldehyde 6. Addition of vinyl magnesium bromide followed by exposure to the first- generation Grubbs catalyst gave the cyclopentenol, that was oxidized to 7. Conjugate silylation led to the triflate 8, that was carried via coupling with 9 to 10. In earlier work, Professor Herzon had shown (Angew. Chem. Int. Ed. 2011, 50, 8863) that the prochiral quinone from oxidation of 11 could be added to the diene 12 under enantioselective catalysis, to give 13 in high ee. Reduction of the azide gave the imine, that was quaternized with methyl triflate. Addition of the Li salt of 10 to that sensitive intermediate proceeded with high facial selectivity. With aromatization blocked, the product from the addition of 10 could be thermolyzed to yield 14. The stannylation of the alkyne proceeded with high regio- and stereoselectivity, to give the alkene 1. Exposure of the allylic silane to tetrabutylammonium fluoride drove the desired cyclization to give 2. Chlorination followed by acetonide removal then completed the preparation of the diol 15. The completion of the synthesis required extensive experimentation. Eventually, a protocol was established to oxidize 15 over several steps to the dienone 16. Selective reduction of the ketone (the other carbonyls are vinylogous esters) proceeded with the desired facial selectivity, to give 17. Selective hydrogenation using a Rh catalyst then delivered (−)-acutumine 3. This is the second total synthesis of (−)-acutumine 3. The first, by Steven L. Castle of Brigham Young University (OHL October 5, 2009), is quite different. It is instructive to compare the two side by side.
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Lambert, Tristan H. "Total Synthesis of C–O Ring-Containing Natural Products." In Organic Synthesis. Oxford University Press, 2015. http://dx.doi.org/10.1093/oso/9780190200794.003.0053.
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Scott A. Snyder at Columbia University demonstrated (J. Am. Chem. Soc. 2012, 134, 17714) that tetrahydrofuran 1 could be readily converted to oxocane 2 by treatment with the BDSB reagent developed in his laboratory. Reduction of 2 with DIBAL-H initiated a second ring closure by mesylate displacement to form the bicycle 3, which represented a formal total synthesis of laurefucin 4. Andrew L. Lawrence at the Australian National University found (Org. Lett. 2012, 14, 4537) that upon treatment with catalytic base, rengyolone 6, which was prepared in one pot from phenol 5, could be converted to the natural products incarviditone 7 and incarvilleatone 8. This demonstration provides strong support for the postulated biomimetic formation of these natural products. Shuanhu Gao at East China Normal University reported (Angew. Chem. Int. Ed. 2012, 51, 7786) the total synthesis of (+)-fusarisetin A 12 via biomimetic oxidation of equisetin 10 to produce the peroxy compound 11, followed by reduction. The bicyclic carbon skeleton of equisetin 10 was synthesized by intramolecular Diels-Alder reaction of trienyl aldehyde 9. The ellagitannin natural product (+)-davidiin 15 possesses a glucopyranose core with the unusual 1C4 (tetraaxial) conformation due to the presence of a biaryl bridge between two of the galloyl groups. Hidetoshi Yamada at Kwansei Gakuin University constructed (Angew. Chem. Int. Ed. 2012, 51, 8026) this bridge by oxidation with CuCl2 of 13, in which the three sterically demanding triisopropylsiloxy groups enforce the requisite tetraaxial conformation. John A. Porco, Jr. at Boston University applied (J. Am. Chem. Soc. 2012, 134, 13108) his asymmetric [3+2] photocycloaddition chemistry to the total synthesis of the aglain natural product (+)-ponapensin 20. Irradiation of hydroxyflavone 16 with methyl cinnamate 17 in the presence of diol 18 afforded the entire core framework 19 of ponapensin 20, which was accessed in just a few further synthetic transformations. Finally, Silas P. Cook at Indiana University reported (J. Am. Chem. Soc. 2012, 134,13577) a five-pot total synthesis of the antimalarial (+)-artemisinin 25. Cyclohexenone 21 was converted by simple operations to aldehyde 22. This aldehyde was then engaged in a [4+2] cycloaddition with the silyl ketene acetal 23 to produce, after an impressive Wacker oxidation of the disubstituted olefin, bicycle 24.
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Taber, Douglass F. "Carbocyclic Construction: The Deng Synthesis of (-)-Plicatic Acid." In Organic Synthesis. Oxford University Press, 2013. http://dx.doi.org/10.1093/oso/9780199965724.003.0079.
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Tehshik P. Yoon of the University of Wisconsin uncovered (J. Am. Chem. Soc. 2009, 131, 14604) conditions for the crossed photodimerization of acyclic enones. Minoru Isobe of Nagoya University extended (Synlett 2009, 1157) conjugate addition–intramolecular epoxide opening to substrates such as 4, leading to the cyclobutane 6 with high diastereocontrol. In the course of a total synthesis of (+)-brefeldin A, Jinsung Tae of Yonsei University established (Synlett 2009, 1303) conditions for the trans-selective cyclization of 7 to 8. Cyclization with TiCl4 gave the alternative cis diastereomer. Several methods have been put forward for the conversion of carbohydrate derivatives to carbocycles. Yeun-Mi Tsai of the National Taiwan University found (Tetrahedron Lett . 2009, 50, 3805) that acyl silanes such as 9 cyclized efficiently under free radical conditions, leading to the silyl ether 10. Tanmaya Pathak of the Indian Institute of Technology, Kharagpur, developed (Eur. J. Org. Chem. 2009, 872) the tandem conjugate addition– intramolecular alkylation conversion of 11 to 13. Slawomir Jarosz of the Polish Academy of Sciences, Warsawza, observed (Heterocycles 2009, 80, 1303) that the oxime derived from 14 cyclized to 15. The cyclization was accelerated by high pressure. Cyclohexanes can also be prepared from carbohydrates. Tony K. M. Shing of the Chinese University of Hong Kong showed (Organic. Lett. 2009, 11, 5070) that the nitrile oxide derived from 16 cyclized to 17, that he carried on to (-)-gabosine O. John K. Gallos of the Aristotle University of Thessaloniki described (Tetrahedron Lett. 2009, 50, 6916) related work. Paul E. Floreancig of the University of Pittsburgh devised (Organic. Lett. 2009, 11, 3152) conditions for the oxidative cyclization of 18 to 19. Ring closure proceeded with high equatorial selectivity. Kou Hiroya of Tohoku University found (J. Org. Chem. 2009, 74, 6623) that the single oxygenated stereogenic center of 20 directed the dissolving metal reduction–enolate trapping, leading to 21. Similarly, Susumu Kobayashi of the Tokyo University of Science showed (Synlett 2009, 1605) that the oxygenated stereogenic centers of 22 set the alkylated centers of 23. Many marine organisms are able to carry out brominative and chlorinative polyolefin cyclizations.
Conference papers on the topic "Silane reduction method"
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Yerrabolu, Santosh Rohit, Joseph C. Mollendorf, Robert E. Baier, and Mark T. Ehrensberger. "Examination of Factors Influencing Intramedullary Reaming Into Femurs." In ASME 2014 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/detc2014-35710.
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This preliminary study explores material surface chemistry modifications to optimize intramedullary (IM) reaming into femurs. Understanding and quantifying the effects of surface chemistry will allow beneficial new material choices. M2 standard High Speed Steel Straight Shank Straight Fluke chucking reamers of 5/32” or ∼4mm diameter were reamed into RenShape®-BM5460 (bone analogs) blocks for the investigation. Sterilizations (Steam Autoclave and Radio Frequency Glow Discharge Treatment) and low friction coatings (Octadecyltrichlorosilane or ODS and 3-Hepta-fluoropropyl-methyl-dichloro-silane or 3-HEPT) were the surface modifications so far pursued in this study. The effects due to the presence of possible transfer films from bone analogs during reaming on cutting efficacies have been investigated on a custom made Orthopaedic Rotational Cutter Analysis System (ORCAS) test system. The results preliminarily suggest a transfer film from the bone analog resulting in reduction of peak loads and peak toques through repeated use. The low-friction coatings have induced lower peak loads and comparable peak torques, suggesting a corollary between low friction coatings and lower surgical efforts required.
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NOVÁK, Petr, Jiří MAŠEK, Josef HŮLA, Lukáš BENEŠ, and Jitka KUMHÁLOVÁ. "SOIL TILLAGE FOCUSING ON THE REDUCTION OF WATER EROSION OF SOIL IN THE CULTIVATION OF SELECTED FIELD CROPS." In Rural Development 2015. Aleksandras Stulginskis University, 2015. http://dx.doi.org/10.15544/rd.2015.015.
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Water erosion is a problem of global significance. Water erosion destroys or damages a vast expanse of usable agricultural land every year. Conditions in the Czech Republic are characterized by high average slope of the land. It is reported that approximately half of land in the Czech Republic is threatened by water erosion. Water erosion is a natural process that cannot be fully prevented. In case of agricultural land an important option is suitable tillage, which may reduce symptoms of water erosion. The problem of water erosion of agricultural land is growing in the Czech Republic, which is mainly caused by the growth of wide areas of crops (maize). This is due to expansion of biogas power plants using parts of maize silage. The aim of paper is to evaluate and assess the crop stand establishment in conditions of resistance to water erosion. For this purpose, a field experiment was set up. This experiment affects the most widely used methods of maize cultivation in Central Bohemia region. It consists of six variants of crops and technologies stand establishment and control treatment without vegetation. To determine the surface runoff and erosive wash was used measurement by runoff microplots. From processed measurement the positive impact of reduced tillage on soil resistance to water erosion results can be confirmed. The consequence is a reduction of surface runoff and especially erosive washes of soil. Impact of ground cover with organic matter is favorable, even in case of conventional tillage. The results of the experiment are directly applicable to agricultural practices. Results of the experiment were used for the legislative recommendations of appropriate technology (wide-row crops on slopes).
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Phan, Ngoc, Crystal Luce, and Courtney Donovan. "Combining Social Betterment and Inclusive Teaching Via Discussion Boards in Basic and Intermediate Statistics." In IASE 2021 Satellite Conference: Statistics Education in the Era of Data Science. International Association for Statistical Education, 2022. http://dx.doi.org/10.52041/iase.aqnfz.
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To use Statistics and Data Science courses to address social injustice, our methods of teaching must aid in deconstructing oppressive ideologies. To truly facilitate transformative learning, we must start by examining how our pedagogies reinforce dominant narratives and silence marginalized perspectives. This requires intentional reflexive methods to create inclusive spaces where individuals critically engage with the material. Mark, Henry, & Julnes (2000) define Social Betterment as “the reduction or prevention of social problems, the improvement of social conditions, and the alleviation of human suffering.” Inclusive Teaching is a pedagogy that focuses on the needs of all students to support course engagement and includes a range of approaches geared towards creating a space that decenters whiteness in statistics education. We combine these into a framework that encourage transformative discourse in introductory and intermediate statistics courses through application discussions alongside content learning.
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Saiki, Kouhei, and Takeshi Watanabe. "Transmission Error Analysis of Helical Gears for Any Load Condition: Practical Calculation Program for Windows PC and Application." In ASME 2000 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/detc2000/ptg-14421.
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Abstract Recently, the gear noise reduction of car transmission, especially for light load condition, is of increasing importance due to the unsparing needs of silence. Since the transmission error is the exciting source of gear noise, the purpose of this study, is to establish an effective method to analyze the transmission error of helical gears with any 3-D tooth surface cutting error for any load condition including light load. The shaft misalignment due to the assembly errors, and the variable shaft deflection caused by the transmitted torque, are also considered. This paper introduces an exact transmission error analysis method of helical gears, in consideration of the nonlinear tooth separation phenomenon at light load condition. As a result, a practical program for Windows personal computer to calculate the transmission error, is also developed. By using this program, the gear designer can find the optimum shape of tooth surface, and the gear producer can evaluate the quality of his manufactured gears. For confirming the proposed analysis method and the calculation program, the tooth contact pattern of several gear pairs are measured and compared with the calculated result. Especially, it is clarified that the transmission performance of the helicoid bias-in tooth surface modification is better than that of the helicoid bias-out tooth surface modification.
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Hwang, Junho, and Hirofumi Daiguji. "Proton Transport in Mesoporous Silica SBA-16 Thin Films With Three-Dimensional Cubic Structures." In ASME 2013 11th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/icnmm2013-73112.
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Mesoporous silica SBA-16 thin films with highly ordered 3D cubic structures were synthesized by evaporation-induced self-assembly method, using an F127 triblock copolymer as the structure-directing agent via dip coating, to investigate proton transport of aqueous solutions confined in mesopores. Using electrochemical measurements of ionic current under DC electric fields, we elucidated proton transport phenomena through mesopores of SBA-16 thin films. At low concentrations, ranging from 10−7 to 10−5 M, the I–V curves of KCl and HCl aqueous solutions were nonlinear. However, at 10−4 and 10−3 M, while I–V curves of KCl aqueous solutions displayed nonlinear behavior, those of HCl aqueous solutions were almost linear. The linear behavior can be attributed to a decrease in the electric potential barrier owing to a reduction in the surface charge density, which is caused by the protonation of silanol groups on the inner surface of mesopores. At high concentrations, ranging from 10−2 to 1 M, the I–V curves of KCl and HCl aqueous solutions were almost linear because the effect of surface charge of mesopores on ion transport was marginal.
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Kawakami, Akihiro, and Takashi Saito. "Study on Vibration Characteristics of Tires Related to Tire-Road Noise of Automobiles." In ASME 2017 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/imece2017-71293.
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The occupants on board are being exposed to an environment in noise and vibration. Among them, the tire-road noise has come to relatively conspicuous because of improvement of silence. To improve comfort for occupants, reduction about the environmental noise and vibration is strongly expected. In this paper, we aim at knowing the vibration characteristics of tires related to tire-road noise of automobiles. Taking two kinds of tires, we carried out the impact tests. One has standard specification and the other has comfort specification absorbing vibration. Setting non-contact and contact to the ground, accelerances are obtained for single fixed input and multi output by impacting tests about tire treads and side-walls. To identify natural angular frequencies, modal damping ratios and modal amplitudes, the real and imaginary parts of accelerance are used in the error function of the optimized problem, which is solved by the down-hill simplex method. Both the natural angular frequencies and modes are identical for two kinds of tires each other. However, it is found that the modal damping ratio of the tire considered to be superior is not much different from the other. It is also found that when the tires contact with the ground, some natural frequencies could increase and other could decrease. Concerning about mode shapes, some axial mode shapes of tread might contradict with those of side-wall.
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Langbein, Sven, Tim Sadek, and Alexander Czechowicz. "Adaptive Resetting of SMA-Actuators." In ASME 2010 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. ASMEDC, 2010. http://dx.doi.org/10.1115/smasis2010-3749.
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Shape Memory Alloys (SMAs) have essential advantages compared to conventional actuators, in particular their high power density and their silent mode of operation. However, this material has not gained acceptance in technical applications yet. The main reasons are the missing simulation tools and a lack of knowledge of materials as well as the companies’ uncertainty how to handle SMAs. The resetting of the SMA element to generate a repeatable movement is often a defined problem. In this context reset springs made of steel are conventional solutions although their characteristics are a disadvantage. To reach a high level of power output and hence a high degree of efficiency, a reduction of the pre-load is necessary. A solution for this problem is an adaptive resetting. One main possibility to generate an adaptive resetting is given by the agonist-antagonist principle where two SMA-elements work against each other. Here the reset force can be applied if necessary. The advantage of this type of design is that a conventional return spring or a mechanical brake for clamping the position (electrically operated) is not necessary. Another possibility for adaptive resetting is to change the spring characteristics of a pseudoelastic SMA-element by heating. The aim of this study is to show the properties of the agonist-antagonist design and the other concepts. It also provides methods and the knowledge to support the development process of such resetting principles. The development of these methods is based on the analysis of different designs and requirements. Based on the results, instructions for the conception of adaptive resetting systems have been created.
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Pfliegler, G., J. Arnout, J. Kienast, K. Wittevrongel, and J. Vermylen. "INSULIN RECEPTORS ARE NOT COUPLED TO THE PHOSPHOINOSITIDE OR ADENYLCYCLASE MESSENGER SYSTEMS IN HUMAN PLATELETS." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644523.
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Insulin receptors have been found not only on its “target Cells” but also on several other cell-types, including human platelets. From studies on adipocytes and liver cells it seems that they are coupled both to the adenylate cyclase-cyclic AMP and the polyphosphoinositide messenger systems. Circulating blood cells might faithfully reflect the insulin receptor state of target organ tissues. Impaired platelet function has an important role in the pathogenesis of vascular and thrombotic complications in diabetes mellitus, and insulin seems to act directly on platelets. A reduction in the number and binding capacity of platelet insulin receptors in diabetic patients (Udvardy et al. 1986) suggested a (patho)physiological role for these receptors. In our studies, insulin (1 × 10-9 - 1 × 10-6 M) did not affect basal platelet cyclic AMP levels, as measured following incorporation of [3H] adenine. Insulin did not prevent PGI2 (25-75 nmol/L) induced cyclic AMP formation in platelets. Insulin did not modify the basal levels of inositol phosphate (IP), IP2 or IP3 in platelets, as measured following incorporation of [3H] inositol. Insulin did not affect formation of IP, IP2 or IP3 by thrombin. No changes in cytosolic free Ca2+ (Quin 2 method) were detected in the presence of insulin. Sodium nitroprusside on the other hand, which is known to mimic several effects of insulin on adipocytes, inhibited IP formation induced by threshold concentrations of thrombin.On the basis of our results the insulin receptors in human platelets seem to be “non-functional” insofar as their occupancy is not accompanied by the stimulation or inhibition of phospho-inositide breakdown or cyclic AMP formation. Similarly, “silent” muscarinic-cholinergic receptors have recently been reported in human erythrocytes (Sehar et al. 1986).
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Conceição, Jamille Karoyne da, and Ana Paula de Mello. "Malnutrition associated with Wallenberg Syndrome: Case report." In XIII Congresso Paulista de Neurologia. Zeppelini Editorial e Comunicação, 2021. http://dx.doi.org/10.5327/1516-3180.599.
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Introduction: Wallenberg Syndrome (SW) is characterized by the condition of swallowing impairment, and nutritional assessment is essential to prevent weight loss. Objective: To report a case of malnutrition associated with SW. Methods: Report of malnutrition in a patient diagnosed with SW in a public hospital in Santa Catarina-Brazil. Results: Elderly, 67 years old, male, retiring, systemic arterial hypertension story and ischemic stroke (without sequelae). He sought assistance on 03/17/2020 in a public hospital in Joinville/SC reporting dysphagia and vertigo, being admitted for investigation of a new vascular event. During hospitalization, he presented: constipation, vertigo, hoarseness, odynophagia, hiccups, regurgitation, emesis, heartburn and drooling. He underwent cranial magnetic resonance imaging confirming infarction in a left posterior-lateral bulb, with a vertebral lesion in the V4 portion, characterizing the SW. He underwent a videodeglutogram, showing a risk of silent bronchoaspiration and with prolonged rehabilitation time, making it necessary to choose an alternative feeding route, initially a nasoenteral tube. Initial anthropometric assessment (03/17/2020): BMI 27.47 kg/m² (height: 163 cm, weight: 73 kg). During hospitalization there was a reduction of -7.9 kg (final weight 65.1 kg; BMI 24.3 kg/m², totaling 10.82% loss (04/23/2020) in 1 month (considered severe). Brachial circumference decreased from 31 (03/24) to 28 cm (04/10). On physical examination: distended abdomen, loss of muscle mass at the temples and subcutaneous fat (biceps). This abrupt nutritional loss was associated with low diet tolerance gastrointestinal night infusion and volumes above 85 ml/h, making it impossible to reach a nutritional goal, he was discharged with gastrostomy, continued to undergo rehabilitation with a speech therapist at home and after 3 months he returned to exclusive oral feeding. Conclusion: Patients diagnosed with SW should be monitored about diet tolerance and to avoid risk of complications associated with weight loss and risk of bronchoaspiration.
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Herrera, Guillermo A., Geoffrey P. McKnight, Xiujie Gao, Nancy Johnson, and Alan L. Browne. "Use of Intrinsic Electrical Resistance Changes in Shape Memory Alloys as Robust Actuator State and Fault Detection Sensors." In ASME 2011 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. ASMEDC, 2011. http://dx.doi.org/10.1115/smasis2011-5000.
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Shape memory alloy (SMA) used as electrically controlled on-demand actuators provide engineers new opportunities to create lighter automated components and devices in vehicles due to their compact size, silent operation, and inherently low mass. Outstanding and critical issues are cost-effective and robust control and protection of the SMA actuator element within the device to achieve long lasting service. SMA responds autonomously to external conditions such as temperature and stress and exhibit many property changes during excitation, but many current devices only use SMA as compact actuators; not making use of their intrinsic sensing capabilities. Inherent SMA property changes during use can provide significant utility for improved optimal control strategies. The motivation for this work is to create a robust control method for electrically controlled SMA actuation to simplify device implementation and improve reliability by using intrinsic material property changes. The current work demonstrates the use of electrical resistance feedback in an integrated controller to allow reduction of parasitic mass, cost, and complexity in 2-position devices. Using signal processing and algorithm logic states, we create virtual sensors that successfully identify start of the actuation, end of actuation, reset, and stress overload events. Using electrical resistance to sense the start of actuation allows successful/repeatable performance over a wide range of environmental conditions. Sensing the end of actuation and reset readiness prevents overheating and allows for shorter actuation cycle times, respectively without additional position and state sensors. While many previous efforts have examined the use of resistance in control schemes, one critical need not addressed in previous controllers is the ability to detect stress overload of the SMA during excitation. To protect against unintentional blocked deployment, many current devices include bulky mechanical overload protection systems that prevent stress spikes and SMA damage accumulation. Using resistance feedback, we demonstrate the detection of stress overloads thus extending device lifetime without the need for external mechanisms. The time derivative of the electrical resistance, logic state of the controller, and detection and use of peak/valley widths and thresholds define control events. These events become software based sensors that can augment or replace dedicated external sensors. Software based sensors were successfully employed to control an SMA wire actuator under various environmental temperatures and stress conditions. The control algorithm is not affected to changes in electrical contact resistance, material degradation and other noise sources yielding a powerful method for simple control of two position SMA devices without the need of external sensors.