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The performance of a film‐based fluorescent sensor is highly dependent on the innovative design of the sensing films aiming to elevate usability of sensing units, and enhance mass transfer of analytes within the fluorescent adlayer. Herein, a highly porous and uniform fluorescent nanofilm which is fabricated through an interfacially confined dynamic‐covalent reaction between benzene‐1,3,5‐tricarbo‐hydrazide and a mono‐boron complex of 8‐hydroxy‐quinoline is reported. Remarkably, the thicknesses of the nanofilms prepared in this way can be modulated from tens to hundreds of nanometers. In addition, the nanofilms demonstrate much improved photochemical stability. Sensing performance studies reveal that the nanofilm is super‐sensitive and selective to the presence of amines, especially methylamine (MA) in vapor phase. Specifically, the detection limit to MA is lower than 2.82 mg m−3, and the presence of the vapors of water, aromatic hydrocarbons, aliphatic hydrocarbons, alcohols, ketones, and other common organic compounds showed little effect upon the sensing. Moreover, the sensing is highly reversible. With the innovation in adlayer structure, substrate effect as commonly found in routine film‐based sensing is avoided, which must bring convenience for device making. In this work, different film‐based sensors are fabricated, suggesting their potential applications in various scenarios. [ABSTRACT FROM AUTHOR]

The voltammetric behaviour of the macrolide based antibiotic: Erythromycin (ERT), Clarithromycin (CLA) and Azithromycin (AZT) was presented in this work. Carbon electrodes and platinum (Pt) electrode were applied as working electrodes. Cyclic voltamograms of each molecule in each electrode were recorded and similar electrochemical behaviour of macrolides was observed for all carbon based electrodes, which gave more defined current intensity peaks than platinum. Other organic compounds were tested trying to clarify electro‐active groups of macrolides. Experiments on mechanism of electrochemical reaction were performed, and studies on the influence of pH on peak current and peak potential were also carried out. [ABSTRACT FROM AUTHOR]

A detailed chemical kinetic model for oxidation of methylamine has been developed, based on theoretical work and a critical evaluation of data from the literature. The rate coefficients for the reactions of CH3NH2 + O2→ CH2NH2 / CH3NH + HO2, CH3NH2 + H → CH3 + NH3, CH3NH → CH2NH2, and CH3NH + O2→ CH2NH + HO2 were calculated from ab initio theory. The mechanism was validated against experimental results from batch reactors, flow reactors, shock tubes, and premixed flames. The model predicts satisfactorily explosion limits for CH3NH2 and its oxidation in a flow reactor. However, oxidation in the presence of nitric oxide, which strongly promotes reaction at lower temperatures, is only described qualitatively. Furthermore, calculated flame speeds are higher than reported experimental values; the model does not capture the inhibiting effect of the NH2 group in CH3NH2 compared to CH4. More work is desirable to confirm the products of the CH3NH + NO reaction and to look into possible pathways to NH3 in methylamine oxidation. [ABSTRACT FROM AUTHOR]

A detailed chemical kinetic model has been developed for supercritical water oxidation (SCWO) of methylamine, CH3NH2, providing insight into the intermediates and final products formed in this process as well as the dominant reaction pathways. The model was adapted from previous mechanisms, with a revision of the peroxyl radical chemistry to include imine formation, which has recently been identified as the dominant gas‐phase pathway in amine oxidation. The developed model can reproduce previous experimental data on methylamine consumption and major product formation to reasonable accuracy, although with deficiencies in describing the induction time. Our simulations indicate that oxidation of the •CH2NH2 radical to methanimine, CH2NH, is the major channel in methylamine SCWO, with subsequent hydrolysis of CH2NH providing the experimentally observed reaction products ammonia and formaldehyde. Integral‐averaged reaction rates were used to identify major reaction pathways, and a first‐order sensitivity analysis indicated that the concentration of CH3NH2 is most sensitive to OH radical kinetics. Overall, this work clarifies the importance of imine chemistry in the oxidation of nitrogen‐containing compounds and indicates that they are necessary to model these compounds in SCWO processes. [ABSTRACT FROM AUTHOR]

The scientific interest in catalytic hydroaminoalkylation reactions of alkenes has vastly increased over the past decade, but these reactions have struggled to become a viable option for general laboratory or industrial use because of reaction times of several days. The titanium‐based catalytic system introduced in this work not only reduces the reaction time by several orders of magnitude, into the range of minutes, but the catalyst is also demonstrated to be easily available from common starting materials, at a cost of approximately 1 € per millimole of catalyst. We were also able to formally perform C−H activation of methylamine and achieve coupling to a broad variety of alkenes, through silyl protection of the amine and simple deprotection by water. [ABSTRACT FROM AUTHOR]

The atmospheric oxidation of amines proceeds via initial radical attack at C–H or N–H bonds to form carbon‐ and nitrogen‐centered radicals, respectively. It is conventionally assumed that nitrogen‐centered aminyl radicals react slowly with oxygen in the troposphere and associate predominantly with the radicals •NO and NO2• to form toxic nitrosamines and nitramines. We have used theoretical kinetic modeling techniques to study the prototypical CH3N•H + O2 reaction and have shown that it proceeds to CH2NH + HO2• under tropospheric conditions with a rate coefficient of 3.6 × 10−17 cm3 molecule−1 s−1. Although this value is low compared to the competing NOx reactions (∼10−11 cm3 molecule−1 s−1), the much higher concentration of O2 versus NOx in air makes it the dominant process in the atmospheric oxidation of methylamine for NOx concentrations below 100 ppb. The mechanism identified here is available to amines with primary, secondary, and tertiary α carbons and suggests that they may be less likely to form nitramines and nitrosamines than is currently thought. [ABSTRACT FROM AUTHOR]

An easy and scalable methylamine (MA) gas healing method was realized for inorganic cesium‐based perovskite (CsPbX3) layers by incorporating a certain amount of MAX (X=I or Br) initiators into the raw film. It was found that the excess MAX accelerated the absorption of the MA gas into the CsPbX3 film and quickly turned it into a liquid intermediate phase. Through the healing process, a highly uniform and highly crystalline CsPbX3 film with enhanced photovoltaic performance was obtained. Moreover, the chemical interactions between a series of halides and MA gas molecules were studied, and the results could offer guidance in further optimizations of the healing strategy. A facile and scalable methylamine (MA) gas healing method for inorganic cesium‐based perovskite (CsPbX3) layers is based on incorporating a certain amount of MAX (X=I or Br) initiators into the raw film. The excess MAX accelerated the absorption of the MA gas into the CsPbX3 film and the formation of a liquid intermediate phase, enabling the formation of a highly uniform and crystalline CsPbX3 film with enhanced photovoltaic performance. [ABSTRACT FROM AUTHOR]

Electrochemical water splitting is one of the most important ways to produce hydrogen fuel for an environmentally friendly energy system. Low‐cost and efficient electrocatalysts for oxygen evolution reaction (OER) have been studied to overcome the sluggish kinetics of OER, which is considered to be a bottleneck that affects the overall efficiency of water splitting. However, the atomic‐level understanding and control of the catalyst surface still remains elusive. Here, we show that methylamine treatment of manganese oxide nanoparticles can effectively control their surface charge and enhance their OER catalytic activity under neutral condition. Methylamine treatment can reduce the overpotential for OER by nearly 100 mV at the current density 5 mA cm−2. Through spectroscopic studies, potentiometric titration, and zeta potential analysis, we discovered that methylamine does not exist on the surface after methylamine treatment but deprotonates the surface of nanoparticles and induce additional negative charge on the surface. Surprisingly, treatment with not only methylamine but other amines can also improve the OER performance and the catalytic activity of the amine treated nanoparticles is influenced by the pKa values of amines. Underwater stars: After methylamine treatment of OH− ligand exchanged Mn3O4 nanoparticles, oxygen evolving reaction performance is significantly enhanced. Detailed mechanistic study reveals that methylamine deprotonates the surface and generates additional negative charges on the surface. The catalytic performance could also be enhanced with different amines and the decrease in overpotential is associated with pKa of amines. [ABSTRACT FROM AUTHOR]

We report herein the discovery of methylamine (CH3NH2) induced defect-healing (MIDH) of CH3NH3PbI3 perovskite thin films based on their ultrafast (seconds), reversible chemical reaction with CH3NH2 gas at room temperature. The key to this healing behavior is the formation and spreading of an intermediate CH3NH3PbI3⋅ xCH3NH2 liquid phase during this unusual perovskite-gas interaction. We demonstrate the versatility and scalability of the MIDH process, and show dramatic enhancement in the performance of perovskite solar cells (PSCs) with MIDH. This study represents a new direction in the formation of defect-free films of hybrid perovskites. [ABSTRACT FROM AUTHOR]

Etching agents, including methylamine (MA) and several others, are used in many studies for exposing the crystal assembly in contrast to amorphous domains in polymer samples, for better morphology contrast. The selection of etching agents must be careful, so as not to alter the original chemical and crystal nature; otherwise misinterpretation may be a consequence. Apparently, the MA-vapor treatment does not simply just induce physical etching through peeling off a covered layer from the polymer samples as many investigators so believed, but also causes severe chemical changes in many aliphatic and aromatic polymers. The chemical reactions between MA and the polyesters ultimately lead to different chemical structures, alteration in spherulites and lamellae, and sometimes completely different lamellar structures with a different melting peak, with C(O)O in the polymers being replaced with C(O)NH bonding. This study uses three examples of polyesters to amply exemplify the necessity of due care in avoiding chemical etching. [ABSTRACT FROM AUTHOR]

The reactions between elemental barium or manganese and tellurium in methylamine under solvothermal conditions at temperatures between 50 and 100 °C yield the tri- and ditellurides [Ba(MeNH2)3]Te3 ( 1) and [Mn(MeNH2)4Te2] n ( 2). The analogous reactions with mixtures of both metals barium and manganese lead additionally to cyanide-containing species [Mn2(MeNH2)9(μ-CN)(Te2)]2(Te2) ( 3) and [Mn2(MeNH2)10(μ-CN)]2(Te3)3 ·4MeNH2 ( 4). Under solvothermal conditions in the presence of metallic barium and manganese methylamine partially undergoes dehydrogenation being converted to cyanide ions. In the structure of 1, Ba2+ is coordinated by three MeNH2 ligands and five tellurium atoms of surrounding Te32- anions, which are associated to infinite (Te32-) n polyanionic chains. 2 is a coordination polymer with Mn(MeNH2)4 groups connected by Te2 units to chains [Te-Te-Mn-] n. 3 and 4 are molecular compounds, consisting of cationic dinuclear complexes with almost linear Mn2+-CN-Mn2+ bridges. In the structures 2- 4 manganese is in octahedral coordination. [ABSTRACT FROM AUTHOR]

Incubation of calf chymosin with the serum from blood of various mammalian species before addition to milk reduced its milk-clotting activity at 30°C; the inhibitory potency of the sera was in the order horse > goat > cattle > donkey = human. For all species, inhibition of calf chymosin increased on increasing both the incubation time and the level of blood serum. Horse blood serum inhibited other milk coagulants in the order porcine pepsin > Cryphonectria parasitica proteinase = calf chymosin > Rhizomucor miehei proteinase = bovine pepsin. Methylamine-treated blood serum did not inhibit calf chymosin, suggesting that α 2 -macroglobulin may be the principal inhibitor of rennet in blood serum. [ABSTRACT FROM AUTHOR]

A very recent laser ablation-molecular beam experiment shows that an Al+ ion can react with a single methylamine (MA, CH3NH2) or dimethylamine (DMA, (CH3)2NH) molecule to form a 1:1 ion–molecule complex Al+[CH3NH2] or Al+[(CH3)2NH)], whereas a dehydrogenated complex ion Cu+[CH3N] or Cu+[C2H5N] is detected, respectively, in the similar reaction for a Cu+ ion. Here, we show a comparative density functional theory study for the reactivities of the Al+ and Cu+ ions toward MA and DMA to reveal the intrinsic mechanism. It is found that the interactions of the Al+ ion with MA and DMA are mostly electrostatic, leading to the direct ion–molecule complexes, Al+&bond;NH2CH3 and Al+&bond;NH( CH3)2, in contrast to the non-negligible covalent character in the corresponding Cu+-containing complexes, Cu+&bond;NH2CH3 and Cu+&bond;NH( CH3)2. The general dehydrogenation mechanism for MA and DMA promoted by the Cu+ ion has been shown, and the preponderant structures contributing to the mass spectra of the product ions Cu+[CH3N] and Cu+[C2H5N] are rationalized as Cu+&bond;NHCH2 and Cu+&bond;N( CH2)( CH3). The presumed dehydrogenation reactions are also discussed for the Al+-containing systems. However, the involved barriers are found to be too high to be overcome at low energy conditions. These results have rationalized all the experimental observations well. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 [ABSTRACT FROM AUTHOR]

Abstract: Prokaryotes, plants and animals control ammonium fluxes by the regulated expression of ammonium transporters (AMTs) and/or the related Rhesus (Rh) proteins. Plant AMTs were previously reported to mediate electrogenic transport. Functional analysis of AtAMT2 from Arabidopsis in yeast and oocytes suggests that is the recruited substrate, but the uncharged form NH3 is conducted. AtAMT2 partially co-localized with electrogenic AMTs and conducted methylamine with low affinity. This transport mechanism may apply to other plant ammonium transporters and explains the different capacities of AMTs to accumulate ammonium in the plant cell. [Copyright &y& Elsevier]

In this article the study of conical intersections (ci) related to the N&bond;H bond in the methylamine, CH3NH2, molecule is extended. In a previous publication (Levi et al., J Chem Phys 2008, 128, 244302) we reported on a novel feature associated with the intersection of the two lowest states 1A' and 1A″ of the methylamine. We established the existence of a finite (closed) line of ci located in the HC&bond;NHH plane—a line that is formed by moving a single hydrogen on that plane while fixing the (six) other atoms. The validity of this line was proved by studying the singularities of the (angular) nonadiabatic coupling terms (NACT)—a study that was later supported by revealing the degeneracy points formed by the two interacting adiabatic potential energy surfaces (PESs). This situation led to two additional interesting features: (i) Along any (open) contour in the above plane that intersects this line is formed a narrow, spiky NACT for which the area under it is ∼π/2; (ii) In case of a closed contour the corresponding topological (Berry) phase is zero (and not an integer multiple of π as is usually the case). In the current article we present the theory to support these findings. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009 [ABSTRACT FROM AUTHOR]

A theoretical study of the mechanism and the kinetics for the hydrogen abstraction reaction of methylamine by OH radical has been presented at the CCSD(T)/6-311 ++G(2d,2p)//CCSD/6-31G(d) level of theory. Our theoretical calculations suggest a stepwise mechanism involving the formation of a prereactant complex in the entrance channel and a preproduct complex in the exit channel, for the two hydrogen abstraction channels involving the methyl and amine groups. For clarity, the diagram of potential for the reaction is given. The calculated standard reaction enthalpies are -98.48 and -76.50 kJ mol-1 and barrier heights are 0.36 and 25.25 kJ mol-1, respectively. The rate constants are evaluated by means of the improved canonical variational transition state theory with small-curvature tunneling correction (ICVT/SCT) in the temperature range of 299–3000 K. The calculated results show that the rate constants at experimentally measured temperatures are in good agreement with the experimental values. It is shown that the calculated rate constants exhibit a non-Arrhenius behavior. Moreover, the variational effect is obvious in the calculated temperature range. The dominant product channel is to form CH2NH2 and H2O via hydrogen abstraction from the CH3 group of CH3NH2 by OH in the calculated temperature range. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009 [ABSTRACT FROM AUTHOR]

We have demonstrated previously that urea inhibits the activity and alters the tertiary structure of skeletal muscle myosin in a biphasic manner. This was attributed to differential effects on its globular and filamentous portion. The inhibition of catalytic activity was counteracted by methylamines. With the aim of comprehending the effects of urea on the catalytic (globular) portion of myosin, this study examines the effects of urea and the countereffects of betaine on the catalytic activity and structure of myosin subfragment-1. It is shown that urea inactivates subfragment-1 in parallel with its ability to induce exposure of the enzyme hydrophobic domains, as assessed using intrinsic and extrinsic fluorescence. Both effects are counteracted by betaine, which alone does not significantly affect subfragment-1. Urea also enhances the accessibility of thiol groups, promotes aggregation and decreases the α-helix content of S1, effects that are also counteracted by betaine. We conclude that urea-induced inactivation of the enzyme is caused by partial unfolding of the myosin catalytic domain. [ABSTRACT FROM AUTHOR]

Ab initio and density functional theory (DFT) calculations were performed for obtaining fundamental vibrational frequencies of methylamine, CH3NH2, and its deuterated variants CH3ND2, CD3NH2, and CD3ND2. The calculations were carried out using the CCSD(T) coupled cluster approximation with cc-pVTZ and cc-pVQZ basis sets, and by the DFT method with the semiempirical hybrid functional B97-1 with polarization consistent pc-2 and pc-3 basis sets. Reasonable performance of the DFT harmonic and ab initio harmonic calculations was found, which improved considerably upon combination of the harmonic fundamental frequencies with anharmonic corrections from the smaller, pc-2, basis. The computed anharmonic fundamental frequencies of methylamine isotopologues agree very well with the experimental values and represent a useful tool for assignment and analysis of the dominant resonances. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2008 [ABSTRACT FROM AUTHOR]

The conjugate Michael addition of methylamine to alkyl acrylates can be performed under mild conditions without a catalyst to obtain new hydrophobic intermediates of aminodiester-type. The reactants used strictly in 1:2 molar ratio provide almost quantitative yield of aminodiesters without formation of undesired aminoesters and any other by-products. Aminodiesters can be purified if necessary by classical methods. The alkyl chain length in the acrylates used has no influence on the results. [ABSTRACT FROM AUTHOR]

We foundN-methyl-l-amino acid dehydrogenase activity in various bacterial strains, such asPseudomonas putidaandBacillus alvei, and cloned the gene fromP. putidaATCC12633 intoEscherichia coli. The enzyme purified to homogeneity from recombinantE. colicatalyzed the NADPH-dependent formation of N-alkyl-l-amino acids from the correspondingα-oxo acids (e.g. pyruvate, phenylpyruvate, and hydroxypyruvate) and alkylamines (e.g. methylamine, ethylamine, and propylamine). Ammonia was inert as a substrate, and the enzyme was clearly distinct from conventional NAD(P)-dependent amino acid dehydrogenases, such as alanine dehydrogenase (EC 1.4.1.1). NADPH was more than 300 times more efficient than NADH as a hydrogen donor in the enzymatic reductive amination. Primary structure analysis revealed that the enzyme belongs to a new NAD(P)-dependent oxidoreductase superfamily, the members of which show no sequence homology to conventional NAD(P)-dependent amino acid dehydrogenases and opine dehydrogenases. [ABSTRACT FROM AUTHOR]

Ammonia and methylamine (MET) are endogenous compounds increased during liver and renal failure, Alzheimer's disease, vascular dementia and diabetes, where they alter some neurobehavioural functions probably acting as potassium channel blockers. We have already described that potassium channel blockers including tetraethylammonium (TEA), ammonia and MET are hypophagic in mice. Antisense oligonucleotides (aODNs) against Shaker-like Kv1.1 gene abolished the effect of TEA but not of ammonia and MET. The central effects elicited in fasted mice by ammonia and MET were further studied. For MET, an ED50 value 71.4 ± 1.8 nmol mouse-1 was calculated. The slope of the dose-response curves for these two compounds and the partial hypophagic effect elicited by ammonia indicated a different action mechanism for these amines. The aODNs pretreatments capable of temporarily reducing the expression of all seven known subtypes of Shaker-like gene or to inactivate specifically the Kv1.6 subtype abolished the hypophagic effect of MET but not that of ammonia. Reverse transcription-polymerase chain reaction, Western blot and immunohistochemical results indicate that a full expression in the brain of Kv1.6 is required only for the activity of MET, and confirms the different action mechanism of ammonia and MET. [ABSTRACT FROM AUTHOR]

The two large-amplitude motions—NH2 wagging and CH3 internal rotation—take place in methylamine, CH3NH2. The complete set of potential and kinematic coupling constants, characterizing the Hamiltonian of a nonrigid molecule CH3NH2 with two large-amplitude coordinates, is derived from standard quantum chemical data for the equilibrium geometries, normal frequencies, and eigenvectors in the ground and transition states. The reconstruction of the Hamiltonian is made via the following steps: classification of the generalized coordinates according to the irreducible representations of the group of the nonrigid molecular model; linear transformation of the ground-state normal coordinates into the frame of the transition state taking into account the Eckart conditions; and perturbative solution of the inverse vibrational problem. It is shown that the consideration of interactions of large-amplitude vibrations with transfer ones significantly affects the parameters of 2-D potential. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004 [ABSTRACT FROM AUTHOR]

The in vivo oxidation of methylamine has been studied in Paracoccus denitrificans. Four components are involved in the electron transfer from methylamine to oxygen; methylamine dehydrogenase (MADH), amicyanin, cytochrome c and eytochrome-c oxidase. In P. denitrificans, MADH and its electron acceptor amicyanin are indispensable for growth on methylamine. In the present study, site-directed mutants have been used to demonstrate participation of cytochrome c550 and the aa3-type cytochrome-c oxidase. Moreover, evidence is provided for the operation of alternative routes, branching from amicyanin, in which at least cytochrome c1 and the cbb3-type cytochrome-c oxidase are involved. [ABSTRACT FROM AUTHOR]

Methylamine uptake in nitrogen-starved Chlorella pyrenoidosa Beif. follows Michaelis-Menten kinetics: maximum uptake is about 1.6 nmol μl[sup-1]·cells·min-1, half-saturation occurs at 4 μM methylamine, and the slope in the range where uptake is proportional to concentrations is 0.4 nmol μl[sup-1]· min[sup-1]·μM[sup-1]. In cells grown in the presence of a non-limiting nitrogen concentration, methylamine uptake is directly proportional to concentration up to at least 0.5 mM, and the slope is 1/500 that for starved cells. Similar uptake kinetics have been reported for Penicillium chrysogenum and attributed to an inducible "ammonium permease." Apparently, a similar permease occurs in algae. [ABSTRACT FROM AUTHOR]

Front Cover: Polarized optical microscopy images of poly(ethylene adiapate), a polyester, are shown in the cover image, before (left) and after (right) 24 hours of etching with methylamine (H3C–NH2). Upon etching, the originally ring‐banded morphology of the polyester is disrupted into a maple leaf‐like structure and chemically changed to an N,N′‐dimethyldiamide linkage. Further details can be found in the article by G. Lugito, L.‐Y. Wang, and E. M. Woo* on page 1297. [ABSTRACT FROM AUTHOR]