Anisotropy of weak light scattering in thin opal films

The forward and backward light scattering that accompanied the almost ballistic light propagation in opal-based three-dimensional photonic crystal (PhC) has been experimentally studied. The light path memory and the high anisotropy of scattering have been associated with low-order scattering at large-scale crystal defects. The strong backscattered light intensity has been linked to the uncoupled light at a PhC surface. The exponent of power-law approximation of angle diagrams of the scattered light intensity has been suggested as a measure of the scattering anisotropy. The scattering anisotropy spectra have demonstrated that in a vicinity to the first photonic bandgap, the lower directionality of the forward scattering is complemented by the higher directionality of the backward scattering

(2+1)-dimensional photonic crystals from Langmuir-Blodgett colloidal multilayers

Angle-resolved transmission spectra of multilayers of two-dimensional colloidal crystals prepared by the Langmuir-Blodgett technique have been studied. In contrast to the light diffraction in three-dimensional colloidal crystals, optical spectra revealed only very weak correlation between layers in the Langmuir-Blodgett multilayers. Two reasons for the observed transmission minima have been identified: the diffraction at a stack of layers and the scattering of the incident beam by guided modes of the two-dimensional colloidal crystals. (c) 2006 American Institute of Physics. (DOI:10.1063/1.2234568

Optical transmission in triple-film hetero-opals

Angle-resolved transmission of s-polarized light in triple-film hetero-opals has been investigated in the spectral range including high-order photonic band gaps, and compared to the transmission of its constituent single-film opals. The interfaces do not destroy the predominantly ballistic light propagation over the studied frequency and angular ranges, but heterostructuring leads to a smoothed angular distribution of intensity of the transmitted light and to the reconstruction of the transmission minima dispersion. The interface transmission function has been extracted by comparing the transmission of the hetero-opal and its components in order to demonstrate the difference. This deviation from the superposition principle was provisionally assigned to light refraction and reflection at the photonic crystal interfaces and to the mismatch between mode group velocities in hetero-opal components

Surface plasmon resonance in gold nanoparticle infiltrated dielectric opals

Light reflectance in three-dimensional metallo-dielectric photonic crystals of polyelectrolyte-coated latex spheres infiltrated with gold nanoparticles has been studied. Broad directional reflectance bands associated with the surface plasmon resonance in the lattice of the gold nanoparticle shells are observed in a wavelength range well separated from the diffraction resonance of the opal lattice. Dependence of surface plasmon resonance spectra on the Au nanoparticle distribution has been demonstrated

Understanding of transmission in the range of high-order photonic bands in thin opal film

Diffraction in the face centered cubic lattice cannot explain some minima observed in the transmission spectra of self-assembled opal films. Here, we compared them with minima observed in the transmission spectra of a hexagonal close packed monolayer of spheres of the same diameter. The identity of the sphere packing on the surface of the opal film and in the sphere monolayer was demonstrated by the light diffraction at the sample surfaces. It was shown that excitation of surface propagating modes in the opal film is responsible for the formation of additional minima in opal film transmission. (C) 2008 American Institute of Physics. (DOI: 10.1063/1.2920443

Erasing diffraction orders: Opal versus Langmuir-Blodgett colloidal crystals

The optical transmission of photonic crystals self-assembled from colloidal nanospheres in opals and assembled from two-dimensional colloidal crystals in a periodic stack by the Langmuir-Blodgett technique has been compared. Elimination of all related zero order diffraction resonances other than that from growth planes and broadening and deepening of the remaining one-dimensional diffraction resonance have been observed for samples prepared by the Langmuir-Blodgett approach, which are explained in terms of the partial disorder of a crystal lattice. (c) 2007 American Institute of Physics.(DOI:10.1063/1.2714198

Modification of emission of CdTe nanocrystals by the local field of Langmuir-Blodgett colloidal photonic crystals

A light source on the surface of a slab of 2+1-dimensional photonic crystal has been prepared by the Langmuir-Blodgett deposition of a colloidal crystal on top of a thin film containing CdTe nanocrystals. The directional enhancement of the light emission intensity in the spectral range of the photonic bandgap has been revealed through the comparative examination of the angle-resolved transmission, diffraction, and photoluminescence spectra of the prepared structures. Changes in the emission spectrum have been tentatively explained in terms of the acceleration of the radiative recombination due to the increase in the local field strength at photonic bandgap resonance and changes in the emission diagram-as arising from the wavelength dependence of the topology of the local field pattern

Signaling pathways mediating β3-adrenergic receptor-induced production of interleukin-6 in adipocytes

The β3-adrenergic receptor (β3AR) is an essential regulator of metabolic and endocrine functions. A major cellular and clinically significant consequence of β3AR activation is the substantial elevation in interleukin-6 (IL-6) levels. Although the β3AR-dependent regulation of IL-6 expression is well established, the cellular pathways underlying this regulation have not been characterized. Using a novel method of homogenous reporters, we assessed the pattern of activation of 43 transcription factors in response to the specific β3AR agonist {"type":"entrez-nucleotide","attrs":{"text":"CL316243","term_id":"44896132","term_text":"CL316243"}}CL316243 in adipocytes, cells that exhibit the highest expression of β3ARs. We observed a unique and robust activation of the CRE-response element, suggesting that IL-6 transcription is regulated via the Gs-protein/cAMP/protein kinase A (PKA) but not nuclear factor kappa B (NF-κB) pathway. However, pretreatment of adipocytes with pharmacologic inhibitors of PKA pathway failed to block β3AR-mediated IL-6 up-regulation. Additionally, stimulation of adipocytes with the exchange protein directly activated by cAMP (Epac) agonist did not induce IL-6 expression. Instead, the β3AR-mediated transcription of IL-6 required activation of both the p38 and PKC pathways. Western blot analysis further showed that transcription factors CREB and ATF-2 but not ATF-1 were activated in a p38- and PKC-dependent manner. Collectively, our results suggest that while stimulation of the β3AR leads to a specific activation of CRE-dependent transcription, there are several independent cellular pathways that converge at the level of CRE-response element activation, and in the case of IL-6 this activation is mediated by p38 and PKC but not PKA pathways

Prolonged and tunable residence time using reversible covalent kinase inhibitors.

Drugs with prolonged on-target residence times often show superior efficacy, yet general strategies for optimizing drug-target residence time are lacking. Here we made progress toward this elusive goal by targeting a noncatalytic cysteine in Bruton's tyrosine kinase (BTK) with reversible covalent inhibitors. Using an inverted orientation of the cysteine-reactive cyanoacrylamide electrophile, we identified potent and selective BTK inhibitors that demonstrated biochemical residence times spanning from minutes to 7 d. An inverted cyanoacrylamide with prolonged residence time in vivo remained bound to BTK for more than 18 h after clearance from the circulation. The inverted cyanoacrylamide strategy was further used to discover fibroblast growth factor receptor (FGFR) kinase inhibitors with residence times of several days, demonstrating the generalizability of the approach. Targeting of noncatalytic cysteines with inverted cyanoacrylamides may serve as a broadly applicable platform that facilitates 'residence time by design', the ability to modulate and improve the duration of target engagement in vivo