Demonstration of all-optical beam steering in modulated photonic lattices

We demonstrate experimentally all-optical beam steering in modulated photonic lattices induced optically by three-beam interference in a biased photorefractive crystal. We identify and characterize the key physical parameters governing the beam steering and show that the spatial resolution can be enhanced by the additional effect of nonlinear beam self-localization.     

Observation of attraction between dark solitons

We demonstrate a dramatic change in the interaction forces between dark solitons in nonlocal nonlinear media. We present what we believe is the first experimental evidence of attraction of dark solitons. Our results indicate that attraction should be observable in other nonlocal systems, such as Bose-Einstein condensates with repulsive long-range interparticle interaction.     

Facile synthesis of the cubic mesoporous material MCM-48. Detailed study of accompanying phase transformations

The synthesis of cubic mesoporous material MCM-48 has been simplified and can be accomplished via facile hydrothermal synthesis using convenient commercial reagents. The cubic structure evolves from the initially formed hexagonal MCM-41 and undergoes slow conversion to the lamellar MCM-50 precursor. The system was sampled at 1 hr intervals and the intermediate products characterized by elemental analysis, X-ray powder diffraction and adsorption. The results are discussed from the standpoint of possible mechanisms of MCM-48 generation.     

Cyclic Just-In-Time Sequences Are Optimal

Consider the Product Rate Variation problem. Given n products 1,...,i,...,n, and n positive integer demands d ₁,..., d_i,...,d_n. Find a sequence =₁,...,_T, T = _i=1 ⁿ d _i, of the products, where product i occurs exactly d _i times that always keeps the actual production level, equal the number of product i occurrences in the prefix ₁,..., _t, t=1,...,T, and the desired production level, equal r _i t, where r _i=d_i/T, of each product i as close to each other as possible. The problem is one of the most fundamental problems in sequencing flexible just-in-time production systems. We show that if is an optimal sequence for d ₁,...,d_i,...,d_n, then concatenation ^m of m copies of is an optimal sequence for md ₁,..., md_i,...,md_n.     

A Fully Polynomial Approximation Scheme for Minimizing Makespan of Deteriorating Jobs

A fully polynomial approximation scheme for the problem of scheduling n deteriorating jobs on a single machine to minimize makespan is presented. Each algorithm of the scheme runs in O(n ⁵ L ⁴³) time, where L is the number of bits in the binary encoding of the largest numerical parameter in the input, and is required relative error. The idea behind the scheme is rather general and it can be used to develop fully polynomial approximation schemes for other combinatorial optimization problems. Main feature of the scheme is that it does not require any prior knowledge of lower and/or upper bounds on the value of optimal solutions.     

Distributions of fluorescence decay times for synthetic melittin in water-methanol mixtures and complexed with calmodulin,troponin C,and phospholipids

Frequency-domain measurements of the intensity decays of melittin were used to recover the distribution of decay times displayed by its single tryptophan residue. Melittin was examined in the monomeric random coil state (water), in the monomeric -helical state (water-methanol), in the tetrameric state, and with 6M guanidine hydrochloride. In the presence of denaturant, where melittin is expected to be devoid of secondary structure, we observed a narrow distribution of lifetimes, similar to a double-exponential decay. In water the intensity decay of melittin was found to be described better by the distribution of decay times, which became progressively wider as the amount of -helix was increased by the methanol cosolvent or upon formation of the -helical tetrameric state. We also examined the intensity decays of melittin when complexed with calmodulin, troponin C, or lipid vesicles of 1-palmitoyl-2-oleyl-l--phosphatidylcholine (POPC). The lifetime distributions of the complexes with lipid were comparable to those observed in methanol-water, suggesting a similarity of the structure and/or dynamics of the environment surrounding the tryptophan residue. A broad lifetime distribution was observed for the melittin-calmodulin complex, suggesting a rigid structure and/or heterogeneity in the form of the complex. The lifetime distribution of the melittin-troponin C complex was more narrow, suggesting a more uniform structure, at least in the region surrounding the tryptophan residue. These results demonstrate that the lifetime distributions of a single tryptophan protein can be a sensitive indicator of the conformational heterogeneity and dynamics of proteins.     

Synthesis of 2-(2′-hydroxyphenyl)pyridine-N-oxide and its thermal decomposition as a model reaction of orellanine deoxidation

2-Methoxyphenylmagnesium bromide was reacted with 2-nitropyridine-N-oxide and demethylated to give 2-(2′-hydroxyphenyl)pyridine-N-oxide (II) which was found to undergo a thermal deoxidation to the free base (VI); the process is interpreted as a [1.5] oxygen shift followed by decomposition of the hydroperoxide intermediate.     

Beiträge zur Chemie der Silicium-Schwefel-Verbindungen. XXXV. Das dimere Thallium(I)-tri-tert-butoxysilanthiolat

Contributions to the Chemistry of Silicon-Sulfur Compounds. XXXV. The Dimeric Thallium(I)-tri-tert-butoxysilanethiolate Thallium(I)-tri-tert-butoxysilanethiolate is formed as a dimer by reaction of tri-tert-butoxysilanethiol with TlNO₃. The compound crystallizes as colourless triclinic plates. F.I. mass spectra show only the mass of the dimeric species (m/e = 968), in the E.I. mass spectra, however, also the peak for the monomeric unit (m/e = 484) is observed. The molecule is of 1 /C_i symmetry. The central four-membered ring is plane, the bond distances and angles therein are d (Tl? S) = 289 pm and S/Tl/S = 91.5°. The Tl atoms are additionally coordinated by an oxygen atom of the tri-tert-butoxysilyl group (d(Tl? O) = 280 pm). The mean bond angle at the threebonded sulfur atom was found to be 90° (d(S? Si) = 207.8 pm). Related details of the structure are discussed (space group P1 ; a = 927.5 pm, b = 1395.1 pm, c = 882.1 pm; α = 108.43°, β = 116.77°, γ = 90.98°; Z = 2; R = 0.032; 2887 reflections hkl).     

Erythrocyte response to near-infrared radiation

The effects of NIR (near-infrared radiation 700-2,000 nm) on bovine erythrocytes in plasma was studied as a continuation of earlier studies. Cell shape was observed and the changes of ratio of hemolysis and electrokinetic potential measured as a function of irradiation time. After 10 min of irradiation, the shape of erythrocyte cells was mainly echinocytic. When these cells were incubated at 311 K for 24 h they regained their initial shape, but fresh erythrocytes that were irradiated for 30 min and aged in vitro did not. These phenomena are due to: (1) the absorption of NIR excitation by hemoglobin; the primary photochemical process being the photo-dissociation of oxyhemoglobin to deoxyhemoglobin. Resulting shape and ratio of hemolysis, structural changes and oxidative stress follow higher deoxyhemoglobin concentration. (2) The absorption of the NIR excitation by proteins, water and lipids. After NIR absorption the membrane surface dehydrates, leading to enhanced protonation and dissociation of hydrogen-bonded complexes. This in turn leads to a change in electrokinetic potential.     

Approaching real-time molecular diagnostics: single-pair fluorescence resonance energy transfer (spFRET) detection for the analysis of low abundant point mutations in K-ras oncogenes

The aim of this study was to develop new strategies for analyzing molecular signatures of disease states approaching real-time using single pair fluorescence resonance energy transfer (spFRET) to rapidly detect point mutations in unamplified genomic DNA. In addition, the detection process was required to discriminate between normal and mutant (minority) DNAs in heterogeneous populations. The discrimination was carried out using allele-specific primers, which flanked the point mutation in the target gene and were ligated using a thermostable ligase enzyme only when the genomic DNA carried this mutation. The allele-specific primers also carried complementary stem structures with end-labels (donor/acceptor fluorescent dyes, Cy5/Cy5.5, respectively), which formed a molecular beacon following ligation. We coupled ligase detection reaction (LDR) with spFRET to identify a single base mutation in codon 12 of a K-ras oncogene that has high diagnostic value for colorectal cancers. A simple diode laser-based fluorescence system capable of interrogating single fluorescent molecules undergoing FRET was used to detect photon bursts generated from the molecular beacon probes formed upon ligation. LDR-spFRET provided the necessary specificity and sensitivity to detect single-point mutations in as little as 600 copies of human genomic DNA directly without PCR at a level of 1 mutant per 1000 wild type sequences using 20 LDR thermal cycles. We also demonstrate the ability to rapidly discriminate single base differences in the K-ras gene in less than 5 min at a frequency of 1 mutant DNA per 10 normals using only a single LDR thermal cycle of genomic DNA (600 copies). Real-time LDR-spFRET detection of point mutations in the K-ras gene was accomplished in PMMA microfluidic devices using sheath flows.