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A straightforward photo-annealing approach was developed for building functional polymer layers on paper. Conducting polyaniline with the ability for photothermal conversion can be readily annealed by near-infrared light. The annealed polymers become both insulating and hydrophobic. Selective photo-annealing produces a functional layer with patterned conductive arrays. This material exhibits real-time response to ammonium gas. Complete photo-annealing preserves the porous structure but changes the wettability of the polyaniline-nanofiber film. [ABSTRACT FROM AUTHOR]

In this paper, we present the synthesis of new selenoloquinoxaline derivatives starting from 2‐chloroquinoxaline‐3‐carbonitrile 1. The compound 1 was subjected to a reaction with selenium metal in the presence of NaBH4 as a reducing agent in ethanol, under a nitrogen atmosphere. This reaction resulted in the formation of the sodium salt of 3‐cyanoquinoxaline‐2‐selenolate, which was subsequently reacted with α‐halogenated carbonyl compounds in situ. This reaction produced a series of newly synthesized 3‐aminoselenolo[2,3‐b]quinoxaline‐2‐substituents. Ethyl 3‐aminoselenolo[2,3‐b]quinoxaline‐2‐carboxylate 3a was hydrolyzed by sodium hydroxide to give the corresponding sodium salt 9. This salt was then refluxed with acetic anhydride to produce oxazinone compound 10. The reaction of compound 10 with ammonium acetate afforded pyrimidoselenolo[2,3‐b]quinoxaline derivative 11. Compound 11 was then chlorinated using phosphorous oxychloride to give the corresponding chlorocompound. [ABSTRACT FROM AUTHOR]

The paper by Gershoni-Poranne and Chen (R. Gershoni-Poranne, P. Chen, Chem. Eur. J. 2017, 23, 4659) gives an incorrect definition of covalent bonding. Furthermore, the assignment of so-called charge shift bonds in ammonium compounds has no physical foundation and is conceptually redundant. [ABSTRACT FROM AUTHOR]

A response to the comment by Gernot Frenking, outlining common ground, as well as differences, with regard to a recent paper on charge-shift bonding in quaternary ammonium cations. [ABSTRACT FROM AUTHOR]

Berberine and berberine chloride as quaternary ammonium salts belong to the rare 'basic natural dyes'. Berberine is e.g. found in the bark of common barberry. It is a yellow natural dye, which dyers appreciate. It is possible to dye wool or leather even without a mordant. Biosynthesis and total synthesis of berberine are described. As an alkaloid, it shows a variety of physiological effects. Formerly used in traditional medicine it is now under intensive pharmacological investigation. We describe the isolation of berberine chloride from barberry bark without chromatography, present its spectra and their interpretations. Besides, barberry fruits are a piquant delicacy of Persian cuisine. A recipe for dyeing and another one for the kitchen round this paper off. Based on a Bachelor thesis this project is a follow up of the recent book 'Classics in Spectroscopy' by S. Berger und D. Sicker (Wiley-VCH 2009). [ABSTRACT FROM AUTHOR]

A novel and efficient approach to sulfonamides has been developed. Using TBHP as the oxidant and NH4I (20 mol%) as the catalyst, arylsulfonyl hydrazides reacted with amines to provide sulfonamides in moderate to good yields. Possible reaction pathway for the formation of the products was also discussed in this paper. [ABSTRACT FROM AUTHOR]

In paper [5] a simplified model for the hydrophobic binding sites of trypsin was proposed, showing where 1-amino-n-alkanes and α,ω-diamino-n-alkanes are bound while they competitively inhibit the catalyzed hydrolysis of a substrate ester. In the model, the enzyme bas two hydrophobic binding sites separated by an aqueous region which presumably contains the catalytic important residues. The first site binds up to 4 methylene groups of the aliphatic side chain adjacent to the ω-amino group: additional—CH2 groups in t, he chain extend into the aqueous region. If the chain is larger than 7 carbon atoms, the additional methylene or methyl groups are bound to the second hydrophobic site. This site is found to bind less strongly than the first site. This paper presents a thermodynamic investigation of the binding properties of trypsin in the formation of complexes with cationic esters and amids which bear an ammonium group on either the end of the acid side chain or the end of the alcohol or amine component. Free energy and in addition enthalpy and entropy of binding were measured as a function of the length of the inhibitor molecule and as a function of the position of the ester or amide carbonyl group. It was found that thc stability of a complex increases linearly with length of the molecule, and that the magnitude of increase depends on the position of the carbonyl group. Amides always exhibit a smaller increase than esters. Inhibitors with the ammonium group on the alcohol component, were bound with about, the same stability than the corresponding ω-aminoacidesters. The results are consistent, with the model. Positioning of the carbonyl group within the first or second binding site reduces stability due to restricted interaction of the hydrophobic residues on enzyme and inhibitor. Only when the carbonyl group falls into the aqueous region, the free energy for an inhibitor containing the ester group is similar to that for a 1-amino-n-alkane with identical chain length. Enthalpy and entropy as functions of the position of the carbonyl group show minima for the position within the aqueous region. This observation is correlated with the jump of enthalpy and entropy of complex formation of trypsin in the series of 1-amino-n-alkanes reported earlier. It is shown that the magnitude of free energy of complex formation with specific substrates is well estimated on basis of the model. As a consequence, the alternative binding of either the 2-N-acyl group or the alcohol or amine component, to the second hydrophobic site may imply a mode of less productive binding. It is emphasized that unproductive binding should be reflected in the Michaelis Menten constants for substrate amides whereas thc Michaelis Menten constant, for a substrate ester is normally not perturbed. [ABSTRACT FROM AUTHOR]

This paper describes a new analytical method, using a combination of ammonium pyrrolidine dithiocarbamate/methyl isobutyl ketone (APDC-MIBK) microextraction and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), for the determination of the concentrations of Cd and Pb in aqueous samples. Only 200 μL of organic solvent was used throughout the entire analysis process, with enhancement factors as high as 25. Recoveries from replicate analyses of natural water [NIST 1640(a)] containing mean concentrations of 3.1 μg Cd L−1 and 9.3 μg Pb L−1 were 95 ± 3 and 104 ± 4%, respectively. The corresponding detection limits were 0.6 μg L −1 for Cd and 0.9 μg L −1 for Pb. The main advantage of this approach is its simplicity in terms of sample preparation, as demonstrated by quantifying the levels of Cd and Pd in real samples, including tap water, groundwater, and seawater, using a standard addition method. [ABSTRACT FROM AUTHOR]

In this paper, a software sensor based on a fuzzy neural network (FNN) approach was proposed for the real-time estimation of nutrient concentrations and overcoming the problem of delayed measure- ments. To improve the FNN performance, fuzzy subtractive clustering was used to identify the model's architecture and optimize the fuzzy rule; meanwhile, a split network structure, applied separately for anaerobic and aerobic conditions, was used with dynamic modeling methods, such as an auto-regressive model with exogenous inputs. The proposed methodology was applied to a bench-scale anoxic/oxic process for biological nitrogen removal. It was possible to partially overcome the extrapolation problem of FNNs with the aid of multi-way principal component analysis, because it has the ability to detect abnormal situations, which could generate extrapolation. Real-time estimation of chemical oxygen demand, nitrate, and ammonium concentrations based on the model was successfully carried out with the simple online information of the anoxic/oxic system. Water Environ. Res., 81, 654 (2009). [ABSTRACT FROM AUTHOR]

Recently, a population of nerves has been described in the aganglionic mouse vas deferens, in which electrically evoked contractions were insensitive to high concentrations of the adrenergic neurone blocker, bretylium. In this paper, the pharmacology of this nerve-evoked contraction has been examined in more detail.Bretylium (20 μM) revealed, after 5 h exposure, a new residual neurogenic contraction (20 stimuli at 10 Hz) that was tetrodotoxin-sensitive.The muscarinic antagonist, cyclopentolate (0.1 and 1 μM), reduced this residual component and the inhibition was reversed by the acetylcholinesterase inhibitor, neostigmine (1 and 10 μM).Nicotine (30 μM) enhanced the residual component revealed by bretylium, suggesting that there are prejunctional nicotinic receptors (nAchRs) influencing acetylcholine (Ach) release.In the presence of prazosin (0.1 μM), a selective α1-adrenoceptor antagonist, and α,β-methylene ATP (1 μM), a purinergic agonist that desensitise P2X receptors, neostigmine increased the hump component of contraction and yohimbine (0.3 μM), an α2-adrenoceptor antagonist, enhanced both components of the electrically evoked stimulation. The contraction was blocked by cyclopentolate (1 μM).In the absence of bretylium, neostigmine alone increased the hump component of contraction in a frequency-dependent manner. This increase was reversed by atropine (1 μM) and cyclopentolate (1 μM) to control levels. However, in control experiments, atropine or cyclopentolate did not detectably influence the delayed neurogenic contraction.Ach (10 μM) induced a contraction in the mouse vas deferens, either when applied alone or in the presence of neostigmine.Thus, it has been demonstrated unequivocally that the mouse vas deferens is innervated by functional cholinergic nerves, whose action is terminated by cholinesterase. Furthermore, Ach release can be enhanced by activation of prejunctional nAchRs presumably located on the cholinergic nerve terminals.British Journal of Pharmacology (2005) 146, 927–934. doi:10.1038/sj.bjp.0706357; published online 19 September 2005 [ABSTRACT FROM AUTHOR]

The paper concerns factors which affect the binding and plaque-inhibiting effect of chlorhexidine-digluconate (CM) in the human oral cavity. About one-third of the administered dose was retained after mouth rinses (0.05-0.40% w/v) and after toothbrushing with a CH gel (1% w/w) measured by [14C]-chlorhexidine. The following CH concentration in saliva showed an almost logarithmic fall during the first 4-8 h, followed by a more steady low concentration, with CH still present after 24 h. The amount retained after mouth rinses increased almost linearly with the increase in the concentration. Time studies showed that about 55% of the amount retained after 60 sec was retained after the first 15 sec. Lowering the pH of the rinsing solution reduced the retention, and increase in ionic strength of after-rinses increased the release of CH. Calcium in a 250 mM concentration significantly reduced the retention and increased the release when present in after-rinses. The detergent sodium dodecyl (lauryl) sulphate greatly reduced both the retention and the plaque-inhibiting effect. Comparative studies between CH and quaternary ammonium compounds showed that 60-65% of the quaternaries was retained, compared to 32% of CH. When used four times daily, the plaque-inhibiting effect of the quaternaries approached that of CH. Their concentration in saliva fell more rapidly than that of CH. [ABSTRACT FROM AUTHOR]

A detailed molecular understanding of the mechanisms of the dephosphorylation of phosphate triesters due to nucleophilic attack can be very useful for the design of nucleophiles that are more efficient. In this work, we report a combined experimental and theoretical study of the reaction of hydroxylamine with paraoxon. The profile of the reaction rate according to pH was determined, and it was found that protonated hydroxylamine was unreactive, while the neutral form reacted via the zwitterion tautomer, with an overall free energy barrier of 23.0 kcal mol‐1. The anionic form was the most reactive, with a free energy barrier of 18.1 kcal mol‐1. Computational calculations revealed 2 mechanisms for the nucleophilic attack of the zwitterion form: the usual backside attack and a new frontside attack mechanism. The former proceeded according to a 2‐step associative mechanism, while the latter was a concerted single‐step mechanism involving attack of the hydroxylamine oxygen on the phosphorus center and interaction of the NH3+ group with the oxygen of the P═O group. The calculations indicated that the free energy barrier for the frontside attack was more favorable than the backside attack by 3 kcal mol‐1, supporting the notion that the observed reaction occurs by frontside attack. The reaction with the anionic hydroxylamine form occurred according to a single‐step concerted ANDN mechanism. This paper presents a one‐step front side ANDN low‐barrier energy profile alternative route to the classic backside mechanism AN + DN for the dephosphorylation of paraoxon by hydroxylamine applying computational methods supported by experimental evidences. [ABSTRACT FROM AUTHOR]