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111.
Paul Goodwin Fotios Petropoulos Rob J. Hyndman 《The Journal of the Operational Research Society》2017,68(9):1082-1084
In forecast value added analysis, the accuracy of relatively sophisticated forecasting methods is compared to that of naïve 1 forecasts to see whether the extra costs and effort of implementing them are justified. In this note, we derive a ratio that indicates the upper bound of a forecasting method’s accuracy relative to naïve 1 forecasts when the mean squared error is used to measure one-period-ahead accuracy. The ratio is applicable when a series is stationary or when its first differences are stationary. Formulae for the ratio are presented for several exemplar time series processes. 相似文献
112.
Dr. Jiangman Sun Dr. Xiao Dong Dr. Yajie Wang Dr. Kuo Li Dr. Haiyan Zheng Dr. Lijuan Wang Dr. George D. Cody Dr. Christopher A. Tulk Jamie J. Molaison Dr. Xiaohuan Lin Dr. Yufei Meng Dr. Changqing Jin Dr. Ho-kwang Mao 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(23):6653-6657
Geometric isomerism in polyacetylene is a basic concept in chemistry textbooks. Polymerization to cis-isomer is kinetically preferred at low temperature, not only in the classic catalytic reaction in solution but also, unexpectedly, in the crystalline phase when it is driven by external pressure without a catalyst. Until now, no perfect reaction route has been proposed for this pressure-induced polymerization. Using in situ neutron diffraction and meta-dynamic simulation, we discovered that under high pressure, acetylene molecules react along a specific crystallographic direction that is perpendicular to those previously proposed. Following this route produces a pure cis-isomer and more surprisingly, predicts that graphane is the final product. Experimentally, polycyclic polymers with a layered structure were identified in the recovered product by solid-state nuclear magnetic resonance and neutron pair distribution functions, which indicates the possibility of synthesizing graphane under high pressure. 相似文献
113.
[reaction: see text] A new halo-Mannich-type reaction is reported using cyclopropyl carbonyl-derived enolates and sulfonyl-protected imines. Chiral oxazolidinones auxiliaries were found to be effective for completely controlling the stereochemistry of the products. Variations in the oxazolidinone, protecting group, and imine components show this to be a quite general reaction. The initial iodo-Mannich products were found to be readily cyclized in the presence of triethylamine to afford the resulting protected pyrrolidines, which could be readily deprotected under standard conditions. 相似文献
114.
115.
Dr. Benjamin A. Chalmers Hui Xing Sevan Houston Dr. Charlotte Clark Dr. Sussan Ghassabian Dr. Andy Kuo Benjamin Cao Andrea Reitsma Cody‐Ellen P. Murray Dr. Jeanette E. Stok Dr. Glen M. Boyle Carly J. Pierce Stuart W. Littler Prof. David A. Winkler Prof. Paul V. Bernhardt Dr. Cielo Pasay Prof. James J. De Voss Prof. James McCarthy Prof. Peter G. Parsons Prof. Gimme H. Walter Prof. Maree T. Smith Prof. Helen M. Cooper Prof. Susan K. Nilsson Dr. John Tsanaktsidis Dr. G. Paul Savage Prof. Craig M. Williams 《Angewandte Chemie (International ed. in English)》2018,57(28):8359-8359
116.
The 5-hexyl (I) and the 5-heptyl (II) analogs of 2,4-diamino-6-methylpyrimidine both crystallize in the space groupP21/c withZ=4. Unit cell parameters of I are C11H20N4·H2O,a=17.204(3),b=4.609(9),c=16.765(2)Å,= 91.53(2)°; those of II are C12H23N4
+·C2H5SO3
–,a=12.489(1),b=16.702(2),c=8.9558(7)Å,=99.208(8)°. The molecular packing of I contains one water, while II forms a salt with ethanesulfonic acid. The alkyl chain of I adopts an alltrans conformation; in contrast, II has onegauche orientation between carbons 2 and 3 of heptyl. These are the first structural data on two alkyl lipophilic antifolates with antineoplastic activity. 相似文献
117.
118.
Yajie Wang Xiao Dong Xingyu Tang Haiyan Zheng Kuo Li Xiaohuan Lin Leiming Fang Guang'ai Sun Xiping Chen Lei Xie Craig L. Bull Nicholas P. Funnell Takanori Hattori Asami Sano‐Furukawa Jihua Chen Dale K. Hensley George D. Cody Yang Ren Hyun Hwi Lee Ho‐kwang Mao 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(5):1482-1487
Pressure‐induced polymerization (PIP) of aromatics is a novel method for constructing sp3‐carbon frameworks, and nanothreads with diamond‐like structures were synthesized by compressing benzene and its derivatives. Here by compressing a benzene‐hexafluorobenzene cocrystal (CHCF), H‐F‐substituted graphane with a layered structure in the PIP product was identified. Based on the crystal structure determined from the in situ neutron diffraction and the intermediate products identified by gas chromatography‐mass spectrum, we found that at 20 GPa CHCF forms tilted columns with benzene and hexafluorobenzene stacked alternatively, and leads to a [4+2] polymer, which then transforms to short‐range ordered H‐F‐substituted graphane. The reaction process involves [4+2] Diels–Alder, retro‐Diels–Alder, and 1‐1′ coupling reactions, and the former is the key reaction in the PIP. These studies confirm the elemental reactions of PIP of CHCF for the first time, and provide insight into the PIP of aromatics. 相似文献
119.
Dustin Bornemann Cody Ross Pitts Carmen J. Ziegler Ewa Pietrasiak Nils Trapp Sebastian Kueng Nico Santschi Antonio Togni 《Angewandte Chemie (International ed. in English)》2019,58(36):12604-12608
The TeF5 group is significantly underexplored as a highly fluorinated substituent on an organic framework, despite it being a larger congener of the acclaimed SF5 group. In fact, only one aryl‐TeF5 compound (phenyl‐TeF5) has been reported to date, synthesized using XeF2. Our recently developed mild TCICA/KF approach to oxidative fluorination provides an affordable and scalable alternative to XeF2. Using this method, we report a scope of extensively characterized aryl‐TeF5 compounds, along with the first SC‐XRD data on this compound class. The methodology was also extended to the synthesis and structural study of heretofore unknown aryl‐TeF4CF3 compounds. Additionally, preliminary reactivity studies unveiled some inconsistencies with previous literature regarding phenyl‐TeF5. Although our studies conclude that the arene‐based TeF5 (and TeF4CF3) group is not quite as robust as the SF5 group, we find that the TeF5 group is more stable than previously thought, thus opening a door to explore new applications of this motif. 相似文献
120.
Robert B. Cody Thierry Fouquet 《Journal of the American Society for Mass Spectrometry》2018,29(10):2110-2113
A modified Kendrick Mass Defect (KMD) analysis was applied to the analysis of polycyclic aromatic hydrocarbons (PAHs) and fullerenes in the diffusion flame from a handheld butane torch. 相似文献