The Experts below are selected from a list of 306 Experts worldwide ranked by ideXlab platform
Chi Sun Poon - One of the best experts on this subject based on the ideXlab platform.
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mixture design and Reaction Sequence for recycling construction wood waste into rapid shaping magnesia phosphate cement particleboard
Industrial & Engineering Chemistry Research, 2017Co-Authors: Lei Wang, Iris K M Yu, Daniel C W Tsang, Shuang Li, Chi Sun PoonAbstract:This study has elucidated the roles of hydration chemistry and Reaction Sequence of magnesia–phosphate cement (MPC) in the upcycling of construction wood waste into rapid-shaping cement-bonded particleboards. The mineralogy and microstructure were evaluated using thermogravimetry, quantitative X-ray diffraction, scanning electron microscopy, and mercury intrusion porosimetry. The results showed that the magnesia-to-phosphate (M/P) ratio controlled the formation of magnesium potassium phosphate hexahydrate (MgKPO4·6H2O, MKP) for strength development. Low M/P ratios gave ill-formed MKP, whereas high M/P ratios resulted in unreacted magnesia. The optimal M/P ratio of 7 led to a much shorter setting time and greater compatibility with wood waste than for ordinary Portland cement. Wood waste can provide a platform for cement hydration and porosity for harboring crystalline MKP and also regulate water release to maintain a moderate MPC Reaction. We also highlight the importance of Reaction Sequence for promotin...
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Mixture Design and Reaction Sequence for Recycling Construction Wood Waste into Rapid-Shaping Magnesia–Phosphate Cement Particleboard
Industrial & Engineering Chemistry Research, 2017Co-Authors: Lei Wang, Daniel C W Tsang, Chi Sun PoonAbstract:This study has elucidated the roles of hydration chemistry and Reaction Sequence of magnesia–phosphate cement (MPC) in the upcycling of construction wood waste into rapid-shaping cement-bonded particleboards. The mineralogy and microstructure were evaluated using thermogravimetry, quantitative X-ray diffraction, scanning electron microscopy, and mercury intrusion porosimetry. The results showed that the magnesia-to-phosphate (M/P) ratio controlled the formation of magnesium potassium phosphate hexahydrate (MgKPO4·6H2O, MKP) for strength development. Low M/P ratios gave ill-formed MKP, whereas high M/P ratios resulted in unreacted magnesia. The optimal M/P ratio of 7 led to a much shorter setting time and greater compatibility with wood waste than for ordinary Portland cement. Wood waste can provide a platform for cement hydration and porosity for harboring crystalline MKP and also regulate water release to maintain a moderate MPC Reaction. We also highlight the importance of Reaction Sequence for promotin...
Steven M George - One of the best experts on this subject based on the ideXlab platform.
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molecular layer deposition of hybrid organic inorganic alucone polymer films using a three step abc Reaction Sequence
Chemistry of Materials, 2009Co-Authors: Byunghoon Yoon, Dragos Seghete, Andrew S Cavanagh, Steven M GeorgeAbstract:Thin film growth using molecular layer deposition (MLD) or atomic layer deposition (ALD) is based on sequential, self-limiting surface Reactions. In this work, MLD is used to grow a hybrid organic−inorganic polymer film based on a three-step ABC Reaction Sequence using trimethylaluminum (TMA), ethanolamine (EA), and maleic anhydride (MA) as the reactants. This three-step ABC Sequence avoids the use of homobifunctional organic precursors by employing a homotrifunctional inorganic reactant (TMA), a heterobifunctional organic reactant (EA), and a ring-opening organic reactant (MA). The resulting hybrid organic−inorganic polymer film is an alucone with an approximate formula of (−AlCH3−OCH2CH2NH−C(O)CHCHCOO−)n. The growth of this ABC alucone film was monitored using in situ Fourier transform infrared (FTIR) measurements at 90−170 °C. The three sequential surface Reactions displayed self-limiting growth. The FTIR difference spectra monitored the absorbance from the surface species during the three surface reac...
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atomic layer controlled growth of sio2 films using binary Reaction Sequence chemistry
Applied Physics Letters, 1997Co-Authors: J W Klaus, A W Ott, J M Johnson, Steven M GeorgeAbstract:SiO2 thin films were deposited with atomic layer control using binary Reaction Sequence chemistry. The SiO2 growth was accomplished by separating the binary Reaction SiCl4+2H2O→SiO2+4HCl into two half-Reactions. Successive application of the half-Reactions in an ABAB… Sequence produced SiO2 deposition at temperatures between 600 and 800 K and reactant pressures of 1–10 Torr. The SiO2 growth was monitored using ellipsometry versus substrate temperature and reactant exposure time. The maximum SiO2 deposition per AB cycle was 1.1 A/AB cycle at 600 K. The surface topography measured using atomic force microscopy was extremely flat with a roughness nearly identical to the initial substrate.
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al3o3 thin film growth on si 100 using binary Reaction Sequence chemistry
Thin Solid Films, 1997Co-Authors: J W Klaus, J M Johnson, Steven M GeorgeAbstract:Al2O3 films with precisely controlled thicknesses and excellent conformality were grown on Si(100) at low temperatures of 350–650 K using sequential surface chemical Reactions. This controlled deposition was achieved by separating a binary Reaction for Al2O3 chemical vapor deposition (2Al(CH3)3 + 3H2O → Al 2O3 + 6CH4) into two half-Reactions:(A)A1OH*+A1(CH3)3→A1OA1(CH3)2*+CH4(B)A1CH3*+H2O→A1OH*+CH4 In the above Reactions, the trimethylaluminum [Al (CH3)3] (TMA) and H2O reactants were employed alternately in an ABAB… binary Reaction Sequence where the asterisks designate the surface species. At the optimal Reaction conditions, a growth rate of 1.1 A per AB cycle was measured on the Si (100) substrate using ellipsometry. These Al 2O3 films had an index of refraction of n= 1.65 and a corresponding density of ρ = 3.50 g cm−3. Additional ellipsometric measurements revealed that the Al2O3 deposition rate per AB cycle decreased at substrate temperatures >450 K. The decrease in the growth rate closely matched the thermal stability of the AlOH*and AlCH3* surface species previously measured with FTIR spectroscopy. This correlation supports a Reaction mechanism based on self-limiting surface chemistry. Atomic force microscope images revealed that the deposited Al 2O3 films were exceptionally flat with a surface roughness of only ± 3 A (rms) after 500 AB cycles and the deposition of a film thickness of ∼ 560 A. The power spectra of the surface topography measured by AFM also demonstrated that the surface roughness was nearly identical for the initial Si(100) substrate and the deposited Al2O3 filmsafter 20–500 AB Reaction cycles.
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atomic layer controlled deposition of al2o3 films using binary Reaction Sequence chemistry
Applied Surface Science, 1996Co-Authors: K C Mccarley, J W Klaus, Steven M GeorgeAbstract:Al2O3 films with precise thicknesses and high conformality were deposited using sequential surface chemical Reactions. To achieve this controlled deposition, a binary Reaction for Al2O3 chemical vapor deposition (2Al(CH3)3 + 3H2O → Al2O3 + 6CH4) was separated into two half-Reactions: (A) AlOH∗ + Al(CH3)3 → AlOAl(CH3)2∗ + CH4, (B) AlCH3∗ + H2O → AlOH∗ + CH4, where the asterisks designate the surface species. Trimethylaluminum (Al(CH3)3) (TMA) and H2O reactants were employed alternately in an ABAB … binary Reaction Sequence to deposit Al2O3 films on single-crystal Si(100) and porous alumina membranes with pore diameters of ∼ 220 A. Ellipsometric measurements obtained a growth rate of 1.1 A/AB cycle on the Si(100) substrate at the optimal Reaction conditions. The Al2O3 films had an index of refraction of n = 1.65 that is consistent with a film density of ϱ = 3.50 g/cm3. Atomic force microscope images revealed that the Al2O3 films were exceptionally flat with a surface roughness of only ±3 A (rms) after the deposition of ∼ 270 A using 250 AB Reaction cycles. Al2O3 films were also deposited inside the pores of Anodisc alumina membranes. Gas flux measurements for H2 and N2 were consistent with a progressive pore reduction versus number of AB Reaction cycles. Porosimetry measurements also showed that the original pore diameter of ∼ 220 A was reduced to ∼ 130 A after 120 AB Reaction cycles.
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atomic layer growth of sio2 on si 100 using sicl4 and h2o in a binary Reaction Sequence
Surface Science, 1995Co-Authors: Ofer Sneh, A W Ott, M L Wise, L A Okada, Steven M GeorgeAbstract:Abstract The atomic layer control of SiO2 growth can be accomplished using binary Reaction Sequence chemistry. To achieve this atomic layer growth, the binary Reaction SiCl4 + 2H2O → SiO2 + 4 HCl can be divided into separate half-Reactions: (A) SiOH ∗ +SiCl 4 →SiOSiCl ∗ 3 +HCl , SiCl ∗ +H 2 O→SiOH ∗ +HCl , where the asterisks designate the surface species. Under the appropriate conditions, each half-Reaction is complete and self-limiting and repetitive ABAB... cycles should produce layer-by-layer-controlled SiO2 deposition. The atomic layer growth of SiO2 thin films on Si(100) was achieved at temperatures from 600–680 K with reactant pressures from 1–50 Torr. These experiments were performed in a small high pressure chamber situated in an ultrahigh vacuum (UHV) apparatus. This design couples high pressure conditions for film growth with an UHV environment for surface analysis using laser-induced thermal desorption (LITD), temperature-programmed desorption (TPD) and Auger electron spectroscopy (AES). The controlled growth of a stoichiometric and chlorine-free SiO2 film on Si(100) was demonstrated using these techniques. SiO2 growth rates of approximately 0.73 ML of oxygen (1.1 A of SiO2) per AB cycle were obtained at 600–680 K. Additional vibrational spectroscopic studies performed in a second vacuum chamber utilized transmission Fourier transform infrared (FTIR) experiments on high surface area, oxidized porous silicon to monitor the surface species during the binary Reaction Sequence chemistry. These FTIR measurements observed the SiCl stretching vibration at 625 cm−1 and the SioH vibration at 3740 cm−1 and confirmed that each half-Reaction was complete and self-limiting. These studies illustrate the feasibility of atomic-layer-controlled SiO2 growth and have determined the reactant pressures and substrate temperatures required for the SiO2 binary Reaction Sequence chemistry.
Bernard L. Flynn - One of the best experts on this subject based on the ideXlab platform.
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An efficient synthesis of (±)-frondosin B using a Stille–Heck Reaction Sequence
Organic & biomolecular chemistry, 2010Co-Authors: Kye-simeon Masters, Bernard L. FlynnAbstract:A concise, convergent synthesis of (±)-frondosin B has been developed based on the application of a Stille–Heck Reaction Sequence of 2-chloro-5-methoxybenzo[b]furan-3-yl triflate and 2-(3-butenyl)-3-(trimethylstannyl)cyclohex-2-enone giving the racemic natural product in a 34% overall yield.
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An efficient synthesis of (plus-minus)-frondosin B using a Stille-Heck Reaction Sequence
Organic and Biomolecular Chemistry, 2010Co-Authors: Kye-simeon Masters, Bernard L. FlynnAbstract:A concise, convergent synthesis of (±)-frondosin B has been developed based on the application of a Stille–Heck Reaction Sequence of 2-chloro-5-methoxybenzo[b]furan-3-yl triflate and 2-(3-butenyl)-3-(trimethylstannyl)cyclohex-2-enone giving the racemic natural product in a 34% overall yield.
Lei Wang - One of the best experts on this subject based on the ideXlab platform.
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mixture design and Reaction Sequence for recycling construction wood waste into rapid shaping magnesia phosphate cement particleboard
Industrial & Engineering Chemistry Research, 2017Co-Authors: Lei Wang, Iris K M Yu, Daniel C W Tsang, Shuang Li, Chi Sun PoonAbstract:This study has elucidated the roles of hydration chemistry and Reaction Sequence of magnesia–phosphate cement (MPC) in the upcycling of construction wood waste into rapid-shaping cement-bonded particleboards. The mineralogy and microstructure were evaluated using thermogravimetry, quantitative X-ray diffraction, scanning electron microscopy, and mercury intrusion porosimetry. The results showed that the magnesia-to-phosphate (M/P) ratio controlled the formation of magnesium potassium phosphate hexahydrate (MgKPO4·6H2O, MKP) for strength development. Low M/P ratios gave ill-formed MKP, whereas high M/P ratios resulted in unreacted magnesia. The optimal M/P ratio of 7 led to a much shorter setting time and greater compatibility with wood waste than for ordinary Portland cement. Wood waste can provide a platform for cement hydration and porosity for harboring crystalline MKP and also regulate water release to maintain a moderate MPC Reaction. We also highlight the importance of Reaction Sequence for promotin...
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Mixture Design and Reaction Sequence for Recycling Construction Wood Waste into Rapid-Shaping Magnesia–Phosphate Cement Particleboard
Industrial & Engineering Chemistry Research, 2017Co-Authors: Lei Wang, Daniel C W Tsang, Chi Sun PoonAbstract:This study has elucidated the roles of hydration chemistry and Reaction Sequence of magnesia–phosphate cement (MPC) in the upcycling of construction wood waste into rapid-shaping cement-bonded particleboards. The mineralogy and microstructure were evaluated using thermogravimetry, quantitative X-ray diffraction, scanning electron microscopy, and mercury intrusion porosimetry. The results showed that the magnesia-to-phosphate (M/P) ratio controlled the formation of magnesium potassium phosphate hexahydrate (MgKPO4·6H2O, MKP) for strength development. Low M/P ratios gave ill-formed MKP, whereas high M/P ratios resulted in unreacted magnesia. The optimal M/P ratio of 7 led to a much shorter setting time and greater compatibility with wood waste than for ordinary Portland cement. Wood waste can provide a platform for cement hydration and porosity for harboring crystalline MKP and also regulate water release to maintain a moderate MPC Reaction. We also highlight the importance of Reaction Sequence for promotin...
Kye-simeon Masters - One of the best experts on this subject based on the ideXlab platform.
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An efficient synthesis of (±)-frondosin B using a Stille–Heck Reaction Sequence
Organic & biomolecular chemistry, 2010Co-Authors: Kye-simeon Masters, Bernard L. FlynnAbstract:A concise, convergent synthesis of (±)-frondosin B has been developed based on the application of a Stille–Heck Reaction Sequence of 2-chloro-5-methoxybenzo[b]furan-3-yl triflate and 2-(3-butenyl)-3-(trimethylstannyl)cyclohex-2-enone giving the racemic natural product in a 34% overall yield.
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An efficient synthesis of (plus-minus)-frondosin B using a Stille-Heck Reaction Sequence
Organic and Biomolecular Chemistry, 2010Co-Authors: Kye-simeon Masters, Bernard L. FlynnAbstract:A concise, convergent synthesis of (±)-frondosin B has been developed based on the application of a Stille–Heck Reaction Sequence of 2-chloro-5-methoxybenzo[b]furan-3-yl triflate and 2-(3-butenyl)-3-(trimethylstannyl)cyclohex-2-enone giving the racemic natural product in a 34% overall yield.
