A discrete carleson theorem along the primes with a restricted supremum

Mathematische Zeitschrift - Consider the discrete maximal function acting on finitely supported functions on the integers, $$\begin{aligned} \mathcal {C}_\Lambda f(n) := \sup _{\lambda \in \Lambda...     

Hydrazone Photoswitches for Structural Modulation of Short Peptides

Molecules that undergo light-driven structural transformations constitute the core components in photoswitchable molecular systems and materials. Among various families of photoswitches, photochromic hydrazones have recently emerged as a novel class of photoswitches with superb properties, such as high photochemical conversion, spectral tunability, thermal stability, and fatigue resistance. Hydrazone photoswitches have been adopted in various adaptive materials at different length scales, however, their utilization for modulating biomolecules still has not been explored. Herein, we present new hydrazone switches that can photomodulate the structures of short peptides. Systematic investigation on a set of hydrazone derivatives revealed that installation of the amide group does not significantly alter the photoswitching behaviors. Importantly, a hydrazone switch comprising an upper phenyl ring and a lower quinolinyl ring was effective for structural control of peptides. We anticipate that this work, as a new milestone in the research of hydrazone switches, will open a new avenue for structural and functional control of biomolecules.     

One-pot sequential synthesis of 1,2-disubstituted benzimidazoles under metal-free conditions

An easy and inexpensive method has been developed to access 1,2-disubstituted benzimidazoles following a one-pot sequential coupling/reduction/cyclization process under metal-free neutral conditions.     

A simple synthesis of nitrogen doped porous graphitic carbon: Electrochemical determination of paracetamol in presence of ascorbic acid and p-aminophenol

Graphite paste electrode modified with nitrogen doped porous carbon (NDPC) is used for the detections of paracetamol (PCM), ascorbic acid (AA) and p-aminophenol (PAP) at relatively low concentration. NDPC is synthesized by direct carbonization of Zn(OAc)₂ incorporated melamine-formaldehyde resin microsphere. The NDPC shows small pore diameters centered at 3.14 nm and 8.12 nm and has a pseudo graphitic structure with reasonable porous matrix. The lower limit of detections (S/N = 3) for PCM, AA, and PAP are found to be 30 nM, 720 nM and 10 nM respectively. Under optimized experimental condition, the linear ranges of determination for PCM and AA are 1–400 μM, 10–2700 μM respectively in mixture. Similarly for PCM and PAP mixture, the linear ranges of determination are found to be 1–90 μM. It is also used for the analysis of urine and pharmaceutical products with better sensitivity.     

The effect of initial acceleration on the waves produced by a moving oscillatory surface pressure

Summary This paper studies the effect of variation of velocity of the oscillatory surface pressure distribution over a finite time interval t₀ on the wave generated from rest. The result of such an acceleration is found to produce the same steady state wave system as it would be if the pressure started impulsively with the uniform velocity at t=t₀. The effect of initial acceleration is felt in the transient part of the wave system.

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Sommario Questa memoria studia l'effetto della variazione di velocità di una distribuzione oscillatoria di pressione superficiale in un intervallo di tempo finito t₀, sull'onda generata a partire dalla quiete. Si trova che questa accelerazione produce lo stesso sistema di onde di regime che si avrebbe se la pressione iniziasse complessivamente con velocità uniforme al tempo t=t₀. L'effetto dell'accelerazione iniziale è sentito nella parte transitoria del sistema di onde.

     

Synthesis of different isoindolone embedded heterocycles with phenolic subunits from a common intermediate, 3-(2′-hydroxyaroyl)-2,3-dihydroisoindol-1-ones

A series of biologically important isoindolone embedded heterocycles such as tetracyclic 2,4-diamino-5-aryl-10-oxo-10H-1,10a-diazaindeno[2,1-a]indene-3-carbonitriles and tricyclic 1-aryl-3,5-dioxo-1H-imidazo-[3,4-b]isoindoles have been synthesized from an easily derived common intermediate, 3-(2′-hydroxyaroyl)-2,3-dihydroisoindol-1-ones. The significant advantages of the present methodologies are the use of simple and easily available starting materials and reagents, operational simplicity, and good yields of the products with high atom-economy.     

An exclusive fluoride receptor: fluoride-induced proton transfer to a quinoline-based thiourea

A new quinoline-based tripodal thiourea has been synthesized, which exclusively binds fluoride anion in DMSO, showing no affinity for other anions including chloride, bromide, iodide, perchlorate, nitrate, and hydrogen sulfate. As investigated by ¹H NMR, the receptor forms both 1:1 and 1:2 complexes yielding binding constants of 2.32(3) (in log β₁) and 4.39(4) (in log β₂), respectively. The quinoline groups are protonated by fluoride-induced proton transfer from the solution to the host molecule. The 1:2 binding is due to the interactions of one fluoride with NH binding sites of urea sites and another fluoride with secondary ⁺NH binding sites within the tripodal pocket. The formation of both 1:1 and 1:2 complexes has been confirmed by theoretical calculations based on density functional theory (DFT).     

Multiple-stage mass spectrometric analysis of complex oligosaccharide antibiotics (everninomicins) in a quadrupole ion trap

Electrospray ionization (ESI) quadrupole ion-trap tandem mass spectrometry (MS/MS) was utilized to characterize a class of complex oligosaccharide antibiotics (everninomicins) that include SCH 27899, everninomicin-D, amino everninomicin (SCH 27900), and SCH 49088 (containing a hydroxylamino-ether sugar). The addition of sodium chloride (approximately 1 microg/mL) facilitates the formation of abundant metal complex ions, and this was used because protonation does not readily occur for most of these compounds. The multiple-stage mass analysis (MS(n)) of the sodiated species provides an important series of fragment ions that are specific for sugar sequence and for some sugar-ring opening. These data suggest a general charge-remote fragmentation pattern with the sodium cation residing in a specific, central location of the sugar chain and fragmentation occurring to trim the end of the molecule. For protonated everninomicin (SCH 27900), however, the proton appears to be mobile during the collisional activation process, opening different fragmentation pathways depending on the proton location. The use of water and acetonitrile with 0.1% acetic acid as the solvent in ESI-MS promotes rapid hydrolysis of the central ortho ester, resulting in the formation of abundant sodiated products that are hydrated. These product ions of the hydrated molecules are likely formed by the same charge-remote fragmentation processes as those that occur for the unhydrolyzed precursor.     

Absorption spectral band width of charge transfer transition of E(T)(30) dye in homogeneous and heterogeneous media

Solvation characteristics in homogeneous and heterogeneous media have been probed by monitoring the band width of ICT band of 2,6-di-phenyl-4(2,4,6-triphenyl-1-pyridino) phenolate, the indicator solute for E(T)(30) scale, in pure, mixed binary solvents and aqueous micellar solution. Non-ideal solvation behaviour is observed in all the binary solvent mixtures. Index of preferential solvation has been calculated as a function of solvent composition. Study in micellar media indicates that the dye is located at the micelle-water interface. The effects of variation of micelle concentration, temperature and electrolyte concentration have also been studies.