Imaging of nanostructures with sub-100?nm spatial resolution using a desktop EUV microscope

Laser-produced plasma sources of short-wavelength radiation offer an interesting alternative to synchrotron and free-electron laser installations. Recently, we reported on a newly developed desktop EUV microscope based on plasma generated from a gas-puff target and diffractive optics. The half-pitch resolution of the microscope approached 50?nm. Compared to analogous microscopes based on synchrotron sources, our system is compact and cost-effective. In this paper, we present the results of imaging experiments on a thin polycrystalline object that was carried out in order to further examine the applicability of the microscope. We have demonstrated here that EUV microscopy can provide structural information that cannot be accessed by conventional optical microscopy or SEM.     

On Martingale Approximation of Adapted Processes

We show that the existence of a martingale approximation of a stationary process depends on the choice of the filtration. There exists a stationary linear process which has a martingale approximation with respect to the natural filtration, but no approximation with respect to a larger filtration with respect to which it is adapted and regular. There exists a stationary process adapted, regular, and having a martingale approximation with respect to a given filtration but not (regular and having a martingale approximation) with respect to the natural filtration.     

In vitro inhibitory activity of essential oil vapors against Ascosphaera apis

This work evaluates the in vitro inhibitory activity of 70 essential oils (EOs) in the vapor phase for the control of Chalkbrood disease caused by Ascosphaera apis Maassen ex Claussen (Olive et Spiltoir). Two wild strains isolated from infected honey bee colonies together with one standard collection strain were tested by the microatmosphere method. From 70 EOs, 39 exhibited an antifungal effect against A. apis standard and wild strains. The greatest antifungal action was observed for EO vapors from Armoracia rusticana, followed by Thymus vulgaris, Cymbopogon flexosus, Origanum vulgare and Allium sativum. An investigation of chemical composition by GC-MS revealed, that the most active EOs contained allyl isothiocyanate, citral, carvacrol and diallyl sulfides as the main constituents. The chemical composition plays a key role, as activities of different EOs from the same botanical species were different according to their composition.     

C-H Bond Functionalization via Hydride Transfer: Formation of α-Arylated Piperidines and 1,2,3,4-Tetrahydroisoquinolines via Stereoselective Intramolecular Amination of Benzylic C-H Bonds

We here report a study of the intramolecular amination of sp(3) C-H bonds via the hydride transfer cyclization of N-tosylimines (HT-amination). In this transformation, 5-aryl aldehydes are subjected to N-toluenesulfonamide in the presence of BF(3)·OEt(2) to effect imine formation and HT-cyclization, leading to 2-arylpiperidines and 3-aryl-1,2,3,4-tetrahydroisoquinolines in a one-pot procedure. We examined the reactivity of a range of aldehyde substrates as a function of their conformational flexibility. Substrates of higher conformational rigidity were more reactive, giving higher yields of the desired products. However, a single substituent on the alkyl chain linking the N-tosylimine and the benzylic sp(3) C-H bonds was sufficient for HT-cyclization to occur. In addition, an examination of various arenes revealed that the electronic character of the hydridic C-H bonds dramatically affects the efficiency of the reaction. We also found that this transformation is highly stereoselective; 2-substituted aldehydes yield cis-2,5-disubstituted piperidines, while 3-substituted aldehydes afford trans-2,4-disubstituted piperidines. The stereoselectivity is a consequence of thermodynamic control. The pseudoallylic strain between the arene and tosyl group on the piperidine ring is proposed to rationalize the greater stability of the isomer with the aryl ring in the axial position. This preferential placement of the arene is proposed to affect the observed stereoselectivity.     

Catalytic coupling of arene C-h bonds and alkynes for the synthesis of coumarins: substrate scope and application to the development of neuroimaging agents

C-H bond functionalization offers strategically novel approaches to complex organic compounds. However, many C-H functionalization reactions suffer from poor compatibility with Lewis basic functional groups, especially amines, which are often essential for biological activity. This study describes a systematic examination of the substrate scope of catalytic hydroarylation in the context of complex amino coumarin synthesis. The choice of substrates was guided by the design and development of the next generation of fluorescent false neurotransmitters (FFNs), neuroimaging probes we recently introduced for optical imaging of neurotransmission in the brain. Comparison of two mild protocols using catalytic PtCl(4) or Au(PPh(3))Cl/AgSbF(6)revealed that each method has a broad and mutually complementary substrate scope. The relatively less active platinum system out-performed the gold catalyst with indole substrates lacking substitution at the C-3 position and provided higher regioselectivity in the case of carbazole-based substrates. On the other hand, the more active gold catalyst demonstrated excellent functional group tolerance, and the ability to catalyze the formation of strained, helical products. The development of these two protocols offers enhanced substrate scope and provides versatile synthetic tools required for the structure-activity examination of FFN neuroimaging probes as well as for the synthesis of complex coumarins in general.     

A necessary and sufficient condition for the existence of an exponential attractor

We give a necessary and sufficient condition for the existence of an exponential attractor. The condition is formulated in the context of metric spaces. It also captures the quantitative properties of the attractor, i.e., the dimension and the rate of attraction. As an application, we show that the evolution operator for the wave equation with nonlinear damping has an exponential attractor.     

Sums of continuous and differentiable functions in dynamical systems

We investigate stability of Martin boundaries for positive solutions of elliptic partial differential equations. We define a perturbation which isG _L ^D -semismall at infinity, show that Martin boundaries are stable under this perturbation, and give sufficient conditions for it. This work was carried out partially while the author was visiting the Department of Mathematics, Technion — Israel Institute of Technology. He wishes to thank the Israel Association for the Promotion of International Scientific Relations, the Japan Society of Promotion of Science, and the Technion.     

Multielement analysis and antioxidant capacity of Merlot wine clones developed in Montenegro

The overall aim of this paper was to compare the multielement composition and antioxidant capacity of two Montenegrin Merlot wines obtained from specific vine clones (VCR1 and VCR 101) along with commercial Merlot wine throughout the consecutive vintages in 2010 and 2011. Elemental composition was analysed using inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS). Additionally, antioxidant capacity was assessed by cyclic voltammetry. VCR 1 wine from 2011 stood out for its elemental composition. On the other hand, antioxidant capacity of VCR 101 wines was the highest one for the both vintages. According to the experimental data obtained, all three wines are good source of essential elements and products with a significant antioxidant activity and specific geographical origin.     

Diversity synthesis via C-H bond functionalization: concept-guided development of new C-arylation methods for imidazoles

Herein, we have formulated the concept of systematic derivatization of a structural motif via C-H bond functionalization. This concept may not only serve as a blueprint for new strategies in diversity synthesis but also provide systematic guidance for the identification of unsolved and important synthetic challenges. To illustrate this point, 2-phenylimidazole was selected as the core motif for this study, a choice inspired by numerous azole-based synthetics, including pharmaceuticals (compound SB 202190), and also fluorescent and chemiluminescent probes. We were able to show that systematic and comprehensive arylation of the 2-phenylimidazole core was feasible, and in the context of this study new arylation methods were developed. The direct 4-arylation of free 2-phenylimidazole was achieved with iodoarenes as the aryl donors in the presence of palladium catalyst (Pd/Ph(3)P) and magnesium oxide as the base. A complete switch from C-4 to C-2' arylation was accomplished using a ruthenium catalyst [CpRu(Ph(3)P)(2)Cl] and Cs(2)CO(3). The corresponding transformations for (N,2)-diphenylimidazole (C-5 and C-2' arylation) were accomplished via the palladium-based method [Pd(OAc)(2)/Ph(3)P/Cs(2)CO(3)] and a rhodium-catalyzed procedure [Rh(acac)(CO)(2)/Cs(2)CO(3)], respectively. All of the arylation methods described herein demonstrated broad synthetic scope, high efficiency, and exclusive selectivity. Furthermore, these new methods proved to be orthogonal to one another and applicable to sequential arylation schemes. With these methods in hand, arrays of arylated imidazoles may now be accessed in a direct manner from 2-phenylimidazole. This strategy stands in sharp contrast to a traditional approach, wherein a distinct and multistep synthesis would be required for each analogue.     

Direct palladium-catalyzed C-2 and C-3 arylation of indoles: a mechanistic rationale for regioselectivity

We have recently developed palladium-catalyzed methods for direct arylation of indoles (and other azoles) wherein high C-2 selectivity was observed for both free (NH)-indole and (NR)-indole. To provide a rationale for the observed selectivity ("nonelectrophilic" regioselectivity), mechanistic studies were conducted, using the phenylation of 1-methylindole as a model system. The reaction order was determined for iodobenzene (zero order), indole (first order), and the catalyst (first order). These kinetic studies, together with the Hammett plot, provided a strong support for the electrophilic palladation pathway. In addition, the kinetic isotope effect (KIE(H/D)) was determined for both C-2 and C-3 positions. A surprisingly large value of 1.6 was found for the C-3 position where the substitution does not occur (secondary KIE), while a smaller value of 1.2 was found at C-2 (apparent primary KIE). On the basis of these findings, a mechanistic interpretation is presented that features an electrophilic palladation of indole, accompanied by a 1,2-migration of an intermediate palladium species. This paradigm was used to design new catalytic conditions for the C-3 arylation of indole. In case of free (NH)-indole, regioselectivity of the arylation reaction (C-2 versus C-3) was achieved by the choice of magnesium base.