Feynman’s Proof of Maxwell Equations: in?the?Context?of Quantum Gravity

Many of us are familiar with Feynman’s “proof” of 1948, as revealed by Dyson, which demonstrates that Maxwell equations of electromagnetism are a consequence of Newton’s laws of motion of classical mechanics and the commutation relations of coordinate and momentum of quantum mechanics. It was Feynman’s purpose to explore the universality of dynamics of particles while making the fewest assumptions. We re-examine this formulation in the context of quantum gravity and show how Feynman’s derivation can be extended to include quantum gravity.     

A new fluorescein derivative bearing a boronic acid group as a fluorescent chemosensor for fluoride ion

A new fluorescein derivative 1 bearing a boronic acid group was investigated as a fluorescent chemosensor for F-. An off-on type fluorescence enhancement was observed by the blocking of the photoinduced electron transfer mechanism, which was induced by the interaction between fluoride and boronic acid moiety.     

Design and analysis of a BLPC vocoder-based adaptive feedback cancellation with probe noise

The band-limited linear predictive coding (BLPC) vocoder-based adaptive feedback cancellation (AFC) removes the high-frequency bias, while the low frequency bias persists between the desired input signal and the loudspeaker signal in the estimate of the feedback path. In this paper, we present a BLPC vocoder-based adaptive feedback canceller with probe noise with an objective of reducing the low-frequency bias in digital hearing-aids. A step-wise mathematical analysis of the proposed feedback canceller is presented employing the recursive least square and normalized least mean square adaptive algorithms. It is observed that the optimal solution of the feedback path is unbiased for an unshaped probe noise, but is biased for a shaped probe signal; the bias term does not consist of correlation between the desired input and the loudspeaker output. The identifiability conditions are analysed and it is shown that a delay, greater than or equal to the length of the adaptive filter, must be introduced in the forward path to achieve an unbiased feedback path estimate. Algorithm analysis and computer simulations presented in this paper justify the reason for selecting the proposed design over the existing BLPC vocoder-based feedback cancellation algorithm.     

Efficient AgOTf or Ph3PAuCl-AgSbF6 catalyzed cyclization of 1-hydroxy-2-alkynylallylphosphonates/2-alkynylallyl alcohols to 2-furylphosphonates/2,3,5-trisubstituted furans

The reaction of 1-hydroxy-2-alkynylallylphosphonates, synthesized by the addition of the corresponding phosphites to 2-alkynylcinnamaldehydes, under AgOTf or Ph₃PAuCl-AgSbF₆ catalyzed cycloisomerization afforded 2-furylphosphonates in good to excellent yields. These cyclization reactions were compared with those of 2-alkynylallyl alcohols that led to multisubstituted furans.     

Palladium-Catalyzed Annulation of Allenes with Indole-2-carboxylic Acid Derivatives: Synthesis of Indolo[2,3-c]pyrane-1-ones via Ar-I Reactivity or C-H Functionalization

Two methodologies, one involving Ar-I reactivity and the other through C-H functionalization, for the formation of indolo[2,3-c]pyrane-1-ones via the corresponding allenes, are presented. A highly efficient approach to indolo[2,3-c]pyrane-1-one derivatives through the Pd-catalyzed regioselective annulation of allenes with 3-iodo-1-alkylindole-2-carboxylic acids is described. This method is fairly general for a wide range of allenes affording the respective indolo[2,3-c]pyrane-1-ones in good to excellent yields. In addition, a Pd(II)-catalyzed oxidative coupling of indole-2-caboxylic acid derivatives with allenes via direct C-H functionalization to afford the corresponding indolo[2,3-c]pyrane-1-ones in moderate to good yields has been developed.     

Top–down mass spectrometry reveals new sequence variants of the major bovine seminal plasma protein PDC‐109

The major protein of bovine seminal plasma, PDC‐109, is a 109‐residue polypeptide that exists as a polydisperse aggregate under native conditions. The oligomeric state of this aggregate varies with ionic strength and the presence of lipids. Binding of PDC‐109 to choline phospholipids on the sperm plasma membrane results in an efflux of cholesterol and choline phospholipids, which is an important step in sperm capacitation. In this study, Fourier transform ion cyclotron resonance mass spectrometry was used to analyze PDC‐109 purified from bovine seminal plasma. In addition to the previously known PDC‐109 variants, four new sequence variants were identified by top–down mass spectrometry. For example, a protein variant containing point mutations P10L and G14R was identified along with another form having a 14‐residue truncation in the N‐terminal region. Two other minor variants could also be identified from the affinity‐purified PDC‐109. These results demonstrate that PDC‐109 is naturally produced as a mixture of several protein forms, most of which have not been detected in previous studies. Native mass spectrometry revealed that PDC‐109 is exclusively monomeric at low protein concentrations, suggesting that the protein oligomers are weakly bound and can easily be disrupted. Ligand binding to PDC‐109 was also investigated, and it was observed that two molecules of O‐phosphorylcholine bind to each PDC‐109 monomer, consistent with previous reports. Copyright © 2012 John Wiley & Sons, Ltd.     

Selective Ortho alkylation of phenol with alcohols over catalysts derived from hydrotalcite-like anionic clays

The vapour phase alkylation of phenol with a series of alcohols containing different number of carbons ranging from C₁ to C₈ were investigated over catalysts derived from magnesium-aluminium hydrotalcite with Mg/Al atomic ratio 3 (MgAl 3.0-HT). The results indicated that at 623 K the catalytic activity for phenol conversion increased with increasing chain length of linear long chain alcohols to give 2-alkylated linear alkyl phenols, without any isomerisation of the alkyl moiety. Isomorphous substitution of Mg²⁺ by Cu²⁺ or Ni²⁺ in the MgAl 3.0-HT resulted in an increase in selectivity of 2-alkyl and 2,6-dialkylphenols (≈60%) in the alkylation of phenol with 1-hexanol or 1-octanol.     

A potassium–18-crown-6 salt of a cyclic myo-inositol phosphate

The six-membered phosphorinane ring in (1,4,7,10,13,16-hexaoxa­cyclo­octa­decane)­potassium 2-O-benzoyl-1,3,5-O-methyl­idyne-myo-in­osi­tol 4,6-cyclo­phosphate trihydrate, [K(C₁₂H₂₄O₆)](C₁₄H₁₂O₉P)·3H₂O, has a boat rather than a chair conformation. The K⁺ ion is eight-coordinate and is connected to one of the phosphate O atoms, one of the O atoms of the myo-inositol residue and the six O atoms of the crown ether.     

Novel Inhibitors of Nicotinamide-N-Methyltransferase for the Treatment of Metabolic Disorders

Nicotinamide-N-methyltransferase (NNMT) is a cytosolic enzyme catalyzing the transfer of a methyl group from S-adenosyl-methionine (SAM) to nicotinamide (Nam). It is expressed in many tissues including the liver, adipose tissue, and skeletal muscle. Its expression in several cancer cell lines has been widely discussed in the literature, and recent work established a link between NNMT expression and metabolic diseases. Here we describe our approach to identify potent small molecule inhibitors of NNMT featuring different binding modes as elucidated by X-ray crystallographic studies.