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431.
Miles M. Crosskey 《Physics letters. A》2011,375(18):1903-1911
We present examples of theoretically-predicted invisibility cloaks with shapes other than spheres and cylinders, including cones and ellipsoids, as well as shapes spliced from parts of these simpler shapes. In addition, we present an example explicitly displaying the non-uniqueness of invisibility cloaks of the same shape. We depict rays propagating through these example cloaks using ray tracing for geometric optics. 相似文献
432.
Manikandan Kadirvel Abdul Gbaj David Mansell Steven M. Miles Biljana Arsic Elena V. Bichenkova Sally Freeman 《Tetrahedron》2008,64(23):5598-5603
The aromatic rings in 4-O-dabsyl-6-O-dansyl-myo-inositol-1,3,5-orthoformate (6) participate in electron transfer causing static quenching as detected by the absence of fluorescence. Upon addition of acid, the orthoformate lock is cleaved, with subsequent conformational change of the myo-inositol ring from penta-axial to the more stable penta-equatorial chair, which causes some increase in fluorescence due to spatial separation of fluorophore and a quencher and reduction in static quenching. In the case of 4,6-O-bisdansyl-myo-inositol-1,3,5-orthoformate (3), the acid-induced removal of the orthoformate lock leads to substantial change of fluorescence following spatial separation of two dansyl groups. 相似文献
433.
The lithio-anion of isoxazole 2 was found to ring open propylene oxide in good yields with complete regioselectivity. Vinylic and benzylic epoxides were utilized as key examples of electrophiles and found to produce a mixture of regioisomeric adducts. Additionally, the use of chiral epoxides was explored, and absolute configuration was determined by X-ray crystallography to prove that nucleophilic attack at the benzylic carbon of (R)-styrene oxide proceeds with 100% inversion at the benzylic carbon to afford the (S)-alcohol (4b). 相似文献
434.
Dr. Uvinduni I. Premadasa Dr. Vera Bocharova Audrey R. Miles Diana Stamberga Stella Belony Dr. Vyacheslav S. Bryantsev Adnan Elgattar Prof. Yi Liao Dr. Joshua T. Damron Dr. Michelle K. Kidder Dr. Benjamin Doughty Dr. Radu Custelcean Dr. Ying-Zhong Ma 《Angewandte Chemie (International ed. in English)》2023,62(29):e202304957
One of the grand challenges underlying current direct air capture (DAC) technologies relates to the intensive energy cost for sorbent regeneration and CO2 release, making the massive scale (GtCO2/year) deployment required to have a positive impact on climate change economically unfeasible. This challenge underscores the critical need to develop new DAC processes with substantially reduced regeneration energies. Here, we report a photochemically-driven approach for CO2 release by exploiting the unique properties of an indazole metastable-state photoacid (mPAH). Our measurements on simulated and amino acid-based DAC systems revealed the potential of mPAH to be used for CO2 release cycles by regulating pH changes and associated isomers driven by light. Upon irradiating with moderate intensity light, a ≈55 % and ≈68 % to ≈78 % conversion of total inorganic carbon to CO2 was found for the simulated and amino acid-based DAC systems, respectively. Our results confirm the feasibility of on-demand CO2 release under ambient conditions using light instead of heat, thereby providing an energy efficient pathway for the regeneration of DAC sorbents. 相似文献
435.
Padgett M Whyte G Girkin J Wright A Allen L Ohberg P Barnett SM 《Optics letters》2006,31(14):2205-2207
When light is transmitted along the axis of a rotating glass rod, the polarization of the light is rotated through a small angle [Proc. R. Soc. London, Ser. A349, 423 (1976)]. Under the same conditions, we predict a rotation of the transmitted image by exactly the same angle. The treatment of the two effects in terms of light's spin and orbital angular momentum suggests that they share a common origin. 相似文献
436.
Davies SG Garner AC Roberts PM Smith AD Sweet MJ Thomson JE 《Organic & biomolecular chemistry》2006,4(14):2753-2768
Homochiral beta-amino esters (prepared on multigram scale by lithium amide conjugate addition) are readily transformed into oxazinanones. N-acyl derivatives of oxazinanones undergo stereoselective enolate alkylation reactions, with higher stereoselectivities observed for the enolate alkylation of (R)-N-propanoyl-4-iso-propyl-6,6-dimethyl-oxazinan-2-one than the corresponding Evans oxazolidin-2-one. A C(4)-iso-propyl stereodirecting group within the oxazinanone conveys higher stereoselectivity than the analogous C(4)-phenyl substituent. gem-Dimethyl substitution at C(6) within the oxazinanone framework facilitates exclusive exocyclic cleavage upon hydrolysis to furnish alpha-substituted carboxylic acid derivatives and the parent oxazinanone in good yield. Asymmetric aldol reactions of a range of aromatic and aliphatic aldehydes with the chlorotitanium enolate of (R)-N-propanoyl-4-iso-propyl-6,6-dimethyl-oxazinan-2-one proceed with excellent diastereoselectivity. Hydrolysis of the aldol products affords homochiral alpha-methyl-beta-hydroxy-carboxylic acids. 相似文献
437.
Gerald Brooks David T. Davies Graham E. Jones Timothy J. Miles Nathan A. Owston Tony W. Peng 《Tetrahedron letters》2010,51(38):5035-5037
This Letter describes the synthesis of challenging pyridyl analogues of 3-oxo-3,4-dihydro-2H-1,4-(benzothiazine or benzoxazine)-6-carbaldehydes. The six different routes described are high yielding, contain no major purification issues and have been used to give gram quantities of each aldehyde. 相似文献
438.
Let f be a transcendental entire function of order less than 1/2. Denote the maximum and minimum modulus of f by M(r, f) = max{|f(z)|: |z| = r} and m(r, f) = min{|f(z)|: |z| = r}. We obtain a minimum modulus condition satisfied by many f of order zero that implies all Fatou components are bounded. A special case of our result is that if
$
\log \log M(r,f) = O(\log r/(\log \log r)^K )
$
\log \log M(r,f) = O(\log r/(\log \log r)^K )
相似文献
439.
Influence of atmospheric turbulence on states of light carrying orbital angular momentum 总被引:2,自引:0,他引:2
B Rodenburg MP Lavery M Malik MN O'Sullivan M Mirhosseini DJ Robertson M Padgett RW Boyd 《Optics letters》2012,37(17):3735-3737
We have experimentally studied the degradation of mode purity for light beams carrying orbital angular momentum (OAM) propagating through simulated atmospheric turbulence. The turbulence is modeled as a randomly varying phase aberration, which obeys statistics postulated by Kolmogorov turbulence theory. We introduce this simulated turbulence through the use of a phase-only spatial light modulator. Once the turbulence is introduced, the degradation in mode quality results in crosstalk between OAM modes. We study this crosstalk in OAM for 11 modes, showing that turbulence uniformly degrades the purity of all the modes within this range, irrespective of mode number. 相似文献
440.
Mathematical Programming - First-order primal-dual methods are appealing for their low memory overhead, fast iterations, and effective parallelization. However, they are often slow at finding high... 相似文献
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