Acylation and alkylation of 1, 3-dimethoxybenzene in polyphosphoric acid

Products of the reaction of 3-halo- and 3-ethoxypropionic acids with 1,3-dimethoxybenzene (4) in polyphosphoric acid have been shown to be 2',4'-dimethoxy-3-(2,4-dimethoxyphenyl)-propiophenone (6) and 1,5-bis[3-(2,4-dimethoxyphenyl)-3-keto-propyl]-2,4-dimethoxybenzene (15) and these have been prepared by unambiguous syntheses. 2',4'-Dimethoxy-3-ethoxypropiophenone (3a) and 2',3,4'- trimethoxypropiophenone (3d) have been synthesized by the reaction of 3-chloro-2',4'-dimethoxypropiophenone (3c) with ethanol and methanol respectively

Enhanced Two-Photon Absorption in a Hollow-Core Photonic Bandgap Fiber

We show that two-photon absorption (TPA) in Rubidium atoms can be greatly enhanced by the use of a hollow-core photonic bandgap fiber. We investigate off-resonant, degenerate Doppler-free TPA on the 5S1/2 - 5D5/2 transition and observe 1% absorption of a pump beam with a total power of only 1 mW in the fiber. These results are verified by measuring the amount of emitted blue fluorescence and are consistent with the theoretical predictions which indicate that transit time effects play an important role in determining the two-photon absorption cross-section in a confined geometry.Comment: 5 pages, 6 figure

Structures of some unusual types of organic compounds

Structures of a variety of compounds isolated in reactions and elucidated with the help of spectral (uv,ir,nmr and mass) data, have been discussed. In a few cases, the assigned structures were confirmed by x-ray crystal structure analysis

Aplikasi Tiket Elektronik Untuk pembayaran Bus Rapid Transit di Kota Makassar

Hasil penelitian menunjukkan bahwa proses transaksi pembayaran tiket Bus Rapid Transit (BRT) menggunakan uang non tunai yang dalam hal ini berupa kode QR yang nantinya di scan oleh supir bus jauh lebih mudah dan cepat dibanding menggunakan uang tunai

Reactions of tetrahalogeno-o-benzoquinones-Part VII. Reaction of alkyl-2-naphthols with tetrachloro-o-benzoquinone

Reaction of 8-methyl-2-naphthol (4a) with the quinone3 gave a mixture of 8-methyl-2,2-(tetrachloro-o-phenylenedioxy)naphthalen-1(2H)-one (1b) and 8-methyl-1,1-(tetrachloro-o-phenylenedioxy)naphthalen-2(1H)-one (2b) in almost equal amounts. Similarly, reaction of the naphthols (4b), (4d) and (4e) with3 gave the corresponding dienones (1c &2c), (1e &2e) and (1f &2f) in almost equal amounts. Reaction of 8-t-butyl-2-naphthol (4c) with3 gave exclusively 8-t-butyl-2,2-(tetrachloro-o-phenylenedioxy)-naphthalen-1(2H)-one (1d). Oxidation of 3-t-butyl-2-naphthol (4f) with3 gave a mixture of 3-t-butyl-2,2-(tetrachloro-o-phenylendioxy) nephthalene-1(2H)-one(1g) and 3-t-butyl-1,1-(tetrachloro-o-phenylenedioxy)naphthelen-2 (1H)-one (2g) in the ratio 1:6. Thus, onlyt-butyl group exherts pronounced steric influence on the rearrangement observed in the reaction of β-naphthol with the quinone3. Structures of all the compounds have been established by spectral data

Faster Algorithms for the Geometric Transportation Problem

Let R, B be a set of n points in R^d, for constant d, where the points of R have integer supplies, points of B have integer demands, and the sum of supply is equal to the sum of demand. Let d(.,.) be a suitable distance function such as the L_p distance. The transportation problem asks to find a map tau : R x B --> N such that sum_{b in B}tau(r,b) = supply(r), sum_{r in R}tau(r,b) = demand(b), and sum_{r in R, b in B} tau(r,b) d(r,b) is minimized. We present three new results for the transportation problem when d(.,.) is any L_p metric: * For any constant epsilon > 0, an O(n^{1+epsilon}) expected time randomized algorithm that returns a transportation map with expected cost O(log^2(1/epsilon)) times the optimal cost. * For any epsilon > 0, a (1+epsilon)-approximation in O(n^{3/2}epsilon^{-d}polylog(U)polylog(n)) time, where U is the maximum supply or demand of any point. * An exact strongly polynomial O(n^2 polylog n) time algorithm, for d = 2

Magnetic resonance studies on the interaction of metal-ion and nucleotide ligands with brain hexokinase

Our previous studies have shown that one manganous ion binds tightly to bovine brain hexokinase, with a Kd =25 ± 4 μM. The characteristic proton relaxation rate (PRR) enhancement of this binary complex (εb) 3 .5 at 9 MHz and 23 °C [ Jarori, G. K. Kasturi, S. R., and Kenkare, U. W. (1981) Arch. Biochem. Biophys. 211,258 - 2681. On the basis of PRR enhancement patterns, observed on the addition of nucleotides ATP and ADP to this E . Mn binary complex, we now show the formation of a nucleotide-bridge ternary complex, enzyme . nucleotide . Mn. Addition of glucose 6-phosphate to enzyme . ATP . Mn, results in a competitive displacement of ATP Mn from the enzyme. However, a quaternary complex E · ADP· Mn· Glc-6-P appears to be formed when both the products are present. β, γ-Bidentate Cr(II1)ATP has been used to elucidate the role of direct binding of Mn(I1) in catalysis, and the stoichiometry of metal-ion interaction with the enzyme in the presence of nucleotide. Bidentate Cr(II1)ATP serves as a substrate for brain hexokinase without any additional requirement for a divalent cation. However, electron-spin resonance studies on the binding of Mn(I1) to the enzyme in the presence of Cr(I1I)ATP suggest that, in the presence of nucleotide, two metal ions interact with hexokinase, one binding directly to the enzyme and the second interacting via the nucleotide bridge. It is this latter one which participates in catalysis. Experiments carried out with hexokinase spin-labeled with 3-(2-iodo-acetamido)-2,2,5,5-tetramethyl-lpyrrolidinyloxyl clearly showed that the direct-binding Mn site on the enzyme is distinctly located from its ATP Mn binding site

Diverse near neighbor problem

Motivated by the recent research on diversity-aware search, we investigate the k-diverse near neighbor reporting problem. The problem is defined as follows: given a query point q, report the maximum diversity set S of k points in the ball of radius r around q. The diversity of a set S is measured by the minimum distance between any pair of points in $S$ (the higher, the better). We present two approximation algorithms for the case where the points live in a d-dimensional Hamming space. Our algorithms guarantee query times that are sub-linear in n and only polynomial in the diversity parameter k, as well as the dimension d. For low values of k, our algorithms achieve sub-linear query times even if the number of points within distance r from a query $q$ is linear in $n$. To the best of our knowledge, these are the first known algorithms of this type that offer provable guarantees.Charles Stark Draper LaboratoryNational Science Foundation (U.S.) (Award NSF CCF-1012042)David & Lucile Packard Foundatio