α-Carbonyl Radicals from N-Enoxybenzotriazoles: De Novo Synthesis of 9-Phenanthrols.

Visible-light-induced energy transfer to N-enoxybenzotriazoles in the presence of hydrogen atom donors or alcoholic solvents led to α-carbonyl radicals. The utility of the α-carbonyl radicals was demonstrated in intramolecular tandem cyclization and in the synthesis of 9-phenanthrols and their analogues. The mechanistic experiments suggested that quenching of the reactive benzotriazolyl radical by the alcohol was accompanied by the formation of an α-hydroxy radical that mediated hydrogen atom transfer or, itself, oxidized into aldehydes.

Energy Transfer Photocatalytic Radical Rearrangement in N-Indolyl Carbonates.

A new type of sp3-like N-centered radical has been generated by selective energy transfer catalysis. Upon photoexcitation, homolytic N-O bond cleavage of N-indolyl carbonate in the presence of an Ir complex produced N- and O-centered radicals. The high spin density at the C3 position of indole led to radical recombination with the O-centered radical, affording valuable 3-oxyindole derivatives without decarboxylation. Transformations of the desired products into various molecules were also demonstrated.

Recent Progress in Enolonium Chemistry under Metal-Free Conditions.

Umpolung approach through inversion of the polarity of conventional enolates, has opened up an unprecedented opportunity in the cross-coupling via alkylation. The enolonium equivalents can be accessed either by hypervalent iodine reagents, activation/oxidation of amides, or the oxidation of alkynes. Under umpolung conditions, highly basic conditions required for classical enolate chemistry can be avoided, and they can couple with unmodified nucleophiles such as heteroatom donors and electron-rich arenes.

Enantioselective Synthesis of Tertiary α,α-Diaryl Carbonyl Compounds Using Chiral N,N'-Dioxides under Umpolung Conditions.

Brønsted acid-catalyzed addition of the chiral N,N'-dioxide into ynamides generated enolonium ions in situ which underwent enantioselective alkylation by indoles, pyrroles, and phenols, without racemization of the formed tertiary center. This external oxidant approach allows for the use of unmodified nucleophiles and does not leave trace groups from the oxidant, which significantly increases the synthetic efficiency and the product diversity. Furthermore, the byproduct of the N,N'-dioxide could be efficiently recycled into an optically pure form.

Fabrication and Comparison of Self-Organized Ag and Au Nanodots on Ti/MgO(001) Substrates.

We analyze and compare the differences in the dewetting phenomena and crystal structure between Ag(5.0 nm) and Au(5.0 nm) layers deposited on a Ti(1.0 nm) seed layer coated onto a MgO(001) substrate. The samples are deposited at room temperature and annealed at 350-450 °C for 5 h. The surfaces of both Ag/Ti and Au/Ti films exhibit a completely separated island structure, subsequently leading to the formation of a nanodot array after annealing. Based on atomic force microscopy (AFM) analysis, we conclude that the dewetting progression speed of Ag/Ti films is higher than that of Au/Ti films. Based on X-ray diffraction (XRD) results, the Ti thin film acts as a seed layer, assisting the epitaxial growth of fcc-Ag(001) nanodots on the MgO(001) substrate, whereas in the case of Au/Ti, the Au layer grows non-epitaxially on the MgO(001) substrate, which is related to the difference in the surface energies of Ag and Au. Furthermore, the optical absorbance spectra of the self-organized Ag and Au nanodots with the Ti seed layer are obtained in the visible light range and the optical properties of Ag and Au nanodots are compared.

A continuous droplet electroporation system for high throughput processing.

A continuous droplet electroporation (EP) system capable of handling a billion cells has been proposed and demonstrated using a proof-of-concept prototype design. Numerical simulations were conducted to design the new system and to compare the continuous droplet EP system with the previous single droplet EP system. Through parametric studies on the applied voltage and flow rate, a much higher cyan fluorescent protein transgene expression efficiency (38.8 ± 8.9%) was accomplished over that of the previous single droplet EP system. A parallel continuous droplet EP system is also demonstrated by introducing additional electrode pairs into the continuous droplet EP system to achieve ultrahigh throughput. Finally, the significance and meaning of the present work and future development direction have been discussed.

Metal-Free Iodine-Catalyzed Oxidation of Ynamides and Diaryl Acetylenes into 1,2-Diketo Compounds.

Metal-free oxidation of ynamides is described, employing pyridine- N-oxides as oxidants under molecular iodine catalysis. In stark contrast to Brønsted acid catalysis, iodophilic activation of ynamides diverts the reaction manifold into a dioxygenation pathway. This oxidation is very rapid at room temperature with only 2.5 mol % I2. Furthermore, this protocol could be extended to nonactivated alkynes, such as diarylacetylenes, to deliver various benzil derivatives.

Brønsted acid-catalyzed α-halogenation of ynamides from halogenated solvents and pyridine-N-oxides.

The keteniminium ions generated from the protonation of ynamides formed reversible adducts with counter anions and pyridine-N-oxides as well as halogenated solvents. Above 80 °C, the halonium ions selectively undergo a rate-limiting attack by pyridine-N-oxides, leading to (E)-haloenamides in good yields.

Asymmetry in hemifield macular thickness as an early indicator of glaucomatous change.

PURPOSE: To investigate whether asymmetry in hemifield macular thickness can serve as an early indicator of glaucomatous structural damage using spectral domain optical coherence tomography. METHODS: Five zones in the macular thickness map were defined. Each zone included reciprocal areas in the superior and inferior hemifield. Differences in average retinal thickness (DRT) between corresponding regional pairs were measured in each of the five zones in 50 healthy eyes. An abnormality was defined as the DRT value lying outside the 95% confidence intervals. An eye was considered to yield an "abnormal macular hemifield test" (MHT) if abnormality was evident in any zone. The sensitivity and specificity for glaucoma detection of MHT and average circumpapillary retinal nerve fiber layer (cRNFL) classification were determined. RESULTS: A total of 114 healthy, 103 glaucoma-suspect, and 74 glaucomatous eyes were included. Overall, 5.8%, 36.9%, 88.4%, and 77.4% of the eyes of the healthy, glaucoma-suspect (GS), early glaucoma (EG), and advanced glaucoma (AG) groups yielded abnormal MHT results, respectively. In EG eyes, the sensitivity of an abnormal MHT result was significantly greater than that of abnormal average cRNFL classification (P=0.008). In the GS and AG groups, the sensitivity did not significantly differ between an abnormal MHT result and an average cRNFL classification (P=0.880, 0.180). Compared with sectoral cRNFL thickness measurements, MHT showed a similar level of diagnostic performance. Specificity was not different between an abnormal MHT result and an average cRNFL classification (P=0.687). CONCLUSIONS: Evaluation of asymmetry in hemifield macular thickness may serve as an assessment tool in the early diagnosis of glaucoma.

Detection of glaucoma by spectral domain-scanning laser ophthalmoscopy/optical coherence tomography (SD-SLO/OCT) and time domain optical coherence tomography.

PURPOSE: To evaluate the relationship between time-domain and spectral domain-scanning laser ophthalmoscopy/optical coherence tomography (SD-SLO/OCT), and to compare the ability of these methods to detect glaucoma. METHODS: Forty-nine glaucoma and 43 healthy participants were imaged by SD-SLO/OCT and Stratus OCT. Bland-Altman plots were used to compare the measurements of retinal nerve fiber layer (RNFL) thickness. Areas under the receiver operating characteristics curves (AUCs), including the average thickness, thickness in each of the 4 quadrants, and thickness at each of the 12 clock-hours were compared. Sensitivity and specificity of normative classification of the 2 OCTs for detection of glaucoma were calculated. RESULTS: The Bland-Altman plot showed good agreement between the 2 instruments. In eyes with glaucoma, RNFL thickness was greater when measured by SD-SLO/OCT than Stratus OCT in most sectors of the eye (Average RNFL thickness: SD-SLO/OCT, 82.7±15.3 µm; Stratus OCT, 76.9±18.4 µm; P<0.001). However, the differences between 2 OCTs were not significant in healthy participants. The AUCs of average RNFL measurements for discrimination of glaucoma did not differ significantly between the instruments (SD-SLO/OCT, 0.969; Stratus OCT, 0.959; P=0.535). SD-SLO/OCT showed similar sensitivity (57.1%) with Stratus OCT (53.4%) for detection of glaucoma in normative classification of average RNFL thickness. CONCLUSIONS: Both OCT technologies did well in the diagnosis of glaucoma. Although there were small differences in the 2 instruments in measured RNFL thickness of glaucomatous eyes, in general there was good agreement between the 2 OCTs. SD-SLO/OCT classified more glaucomatous eyes as abnormal based on its normative database.

Comparison of retinal nerve fibre layer thickness measurements calculated by the optic nerve head map (NHM4) and RNFL3.45 modes of spectral-domain optical coherence tomography (RTVue-100).

AIM: To evaluate and compare retinal nerve fibre layer (RNFL) thickness measured by direct scanning (RNFL3.45 mode) and re-sampling from datasets (NHM4 mode) of RTVue-100 optical coherence tomography (OCT). METHODS: Thirty-six healthy subjects and 76 subjects with glaucoma were imaged with Stratus OCT (fast RNFL mode, RNFL3) and RTVue-100 OCT (NHM4 (RNFL1) and RNFL3.45 (RNFL2) modes). Measurement reproducibility was assessed in NHM4 and RNFL3.45 modes of RTVue-100 OCT (intraclass correlation coefficient (ICC)). Agreement between different RNFL measurements was analysed by Bland-Altman plot. The areas under the receiver operating characteristic (ROC) curves (AUCs) for discrimination between healthy and glaucoma were compared between the different RNFL measurements. RESULTS: Both NHM4 and RNFL3.45 modes showed excellent measurement reproducibilities (ICC 0.831-0.978). RNFL thicknesses by two different modes of the RTVue-100 OCT, and by the Stratus OCT, were correlated in all sectors, including average. There was no significant difference between RNFL1 and RNFL2 data. However, RNFL thickness in glaucomatous eyes by the RTVue-100 OCT was significantly greater than that measured by Stratus OCT. RNFL thicknesses determined by the two different modes of RTVue-100 OCT were in excellent agreement (95% limits of agreement -6.53 to 6.95 mum). All three RNFL measurements showed good glaucoma discrimination ability (AUC = RNFL1 0.970, RNFL2 0.962, RNFL3 0.971). CONCLUSIONS: RNFL thickness determined by direct scanning and re-sampling from datasets of RTVue-100 OCT were in good agreement. However, both measurements in glaucomatous subjects were significantly different from those with the Stratus OCT. Those findings should be considered when a patient is followed-up using different types of OCT.

Macular and peripapillary retinal nerve fiber layer measurements by spectral domain optical coherence tomography in normal-tension glaucoma.

PURPOSE: To evaluate and compare the glaucoma discrimination ability of macular inner retinal layer (MIRL) thickness with that of peripapillary retinal nerve fiber layer (pRNFL) thickness measured by spectral-domain optical coherence tomography (RTVue-100; Optovue Inc, Fremont, CA) in patients with normal-tension glaucoma (NTG). METHODS: Sixty-five healthy subjects and 102 with NTG were enrolled. MIRL thickness provided by a ganglion cell complex (GCC) scan and two RNFL thicknesses measured by the NHM4 (RNFL1) and RNFL 3.45 (RNFL2) modes of the RTVue-100 system were analyzed. The areas under the receiver operating characteristic curves (AUCs) of MIRL and pRNFL thicknesses for discriminating patients with NTG from control subjects were determined. The AUCs were compared between patients with central visual field (VF) defects (VF; 10 degrees from fixation). RESULTS: The average MIRL thickness showed a strong correlation with both RNFL1 and -2 thicknesses (R(2) = 0.773, 0.774, both P < 0.0001). The AUCs for average MIRL, RNFL1, and RNFL2 thicknesses were not significantly different at 0.945, 0.973, and 0.976, respectively. However, the AUCs of the average and superior MIRL thicknesses were significantly less than that of the pRNFL thickness in eyes with moderate-to-advanced glaucoma and eyes with peripheral VF defects. CONCLUSIONS: The average MIRL thickness showed a strong correlation with pRNFL thickness, because patients with NTG at an early stage showed paracentral VF defects near the fixation point. MIRL thickness showed glaucoma discrimination ability comparable to that of pRNFL thickness in patients with NTG with early VF defects. In eyes with advanced or peripheral VF defect, pRNFL measurement showed a better glaucoma diagnostic ability than did MIRL measurement.