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INTRODUCTION: Adult sea lamprey (Petromyzon marinus) cease feeding and migrate to spawning streams where males build nests, undergo final sexual maturation, and subsequently produce and release large quantities of bile acid pheromones that attract mature females. These animals are predicted to rearrange their metabolic pathways drastically to support their reproductive strategies, presenting advantageous opportunities to examine how sex and the maturation processes affect metabolism. OBJECTIVES: The objective is to investigate the metabolic differences between sexes and maturation states in sea lamprey that support changes in physiological functions. METHODS: We compared plasma metabolomes of spawning and prespawning sea lamprey in both sexes using both non-targeted and targeted metabolomics approaches using UPLC/MS-MS with electrospray ionization in both positive and negative modes. The data were processed using Progenesis QI, Compound Discoverer and XCMS softwares for alignment, peak picking, and deconvolution of the peaks. Principle component analyses (PCA) and partial least squares discriminant analyses (PLS-DA) were performed using SIMCA and Metaboanalyst softwares to identify discriminating features, followed by fragmentation matching with extensive database search and pathway mapping. RESULTS: The pheromonal bile acid biosynthesis was upregulated significantly in males compared to females. Spermiating males further upregulated bile acid biosynthesis by altering amino acid metabolisms, upregulating cofactors and nucleotide metabolisms, but downregulating carbohydrate and energy metabolisms. CONCLUSION: Plasma metabolomes are sex- and maturation-dependent and reflect the special metabolic demands at each life stage and reproductive strategy.

The heats of reaction of CuO-Cu(OH)2-H2O samples with aqueous HClO4 have been obtained as a function of concentration. Extrapolated to the normal standard state, the values are ΔH°298 = -15.00 and -15.37 kcal. per mole for CuO and Cu(OH)2, respectively. These data are consistent with thermochemical paths based on data in the literature. The entropy of Cu2+(aq) has been determined as -21.5 ± 1.5 cal. per mole 0 K. No evidence was obtained for stable “hydrates” of CuO in the H2O/CuO range 0 to 1.25. © 1969, American Chemical Society. All rights reserved.

The reaction of 2,2′-bipyridylamine (abbreviated BPAH) with divalent nickel salts results in the formation of several products, the type of which depends on the metal:ligand ratio and the coordinating ability of the associated anion. Thus, tetrahedral [Ni(BPAH)Cl2] and octahedral [Ni(BPAH)3] (ClO4)2 and [Ni(BPAH)2Cl2] have been isolated and characterized. In these complexes, dipyridylamine coordinates in a bidentate manner through the two pyridine nitrogens. Deprotonation of the amine at ambient temperature in butanol results in the conversion of the paramagnetic [Ni(BPAH)2Cl2] species into a six-coordinate polymeric material of the general formula Ni(BPA)2 where the deprotonated bipyridylamine moiety (ab¬breviated BPA) is coordinating in a tridentate manner with the amine nitrogen acting as a bridge. This polymer is cleaved quite readily by the action of water, pyridine, and, presumably, other complexing solvents. Deprotonation of [Ni(BPAH)-Cl2] at high temperatures in naphthalene or reaction of the deprotonated polymer with nickel(II) chloride, also at high temperatures, yields a red crystalline trinuclear complex of the molecular formula [Ni3(BPA)4Cl2]. Deprotonation of bis(2,2′-bipyridylamine)copper(II) chloride and bis(2,2′-bipyridylamine)palladium(II) perchlorate give the expected four-coordinate square-planar product. The deprotonated complexes of palladium, copper, and nickel are compared and corre¬lations are made between their ease of formation and the geometry and electronic arrangement of the central metal ion. © 1968, American Chemical Society. All rights reserved.

The action of phosgene on N, N'-disubstituted ureas is described in literature as giving a variety of products depending upon the reaction conditions. However, in no instance has the formation of N, N', N''-trisubstituted guanidines been reported from the above reaction. A novel synthesis is now presented in which these aforementioned guanidines are obtained. This reaction involves the phosgenation of N, N'-dialkyl- or N-alkyl-N'-arylureas at temperatures between 110 and 120° in an inert solvent such as monochlorobenzene. In the case of symmetrically disubstituted alkylureas, the N, N', N''-trialkylguanidines in the form of their hydrochloride salts are obtained. Unsymmetrically substituted ureas upon phosgenation also give guanidines, the type of which, in terms of their substituents, is dependent upon the ability of the urea nitrogen to act as a nucleophile as well as the steric nature of the substituent itself. Thus, phosgenation of N-cyclohexyl-N'-phenylurea gives N, N'-dicyclohexyl-N''-phenylguanidine exclusively. In cases where the substituents on nitrogen atoms of the urea molecule are alike in electron-donating abilities, product distributions are obtained, as with Ncyclohexyl-N'-isopropylurea. Where one urea nitrogen is strongly deactivated, as with N-cyclohexyl-N'-trifluoroethylurea, there is no indication of guanadine formation. Different types of compounds are isolated from these reactions. A mechanism is proposed to account for these observed patterns. Copyright © 1967, American Chemical Society. All rights reserved.

Several cobalt(III) complexes of the V-hydroxyethyliminodiacetate ion (“heida”) have been prepared. Infrared and nmr studies, as well as exchange studies with D2O, show that the ligand tends to be tridentate and that the alcoholic hydroxyl group does not coordinate. Moreover, the alcoholic group in the complex can be acetylated without destruction of the complex. However, in [Co(en)(heida)]0, the alcoholic OH loses its proton, and the ligand becomes trinegative and tetradentate. © 1974, American Chemical Society. All rights reserved.

(Matrix Presented) Treatment of aniline with n-butyllithium and then trimethyltin chloride gave the tin amide (PhNH-SnMe3) in situ. Without isolation of the tin amide reaction with bromine and workup with aqueous fluoride ion gave p-bromoaniline in 76% yield, with no dibromoaniline or o-bromoaniline. Application of this sequence to 11 different aromatic amines gave selective bromination in 36-91% yields, without formation of dibromides. This constitutes a good general method for the regioselective bromination of aromatic amines.

Those familiar with the goals of SENCER and those who attend the regional meetings and Summer Institutes understand the transformative impact this approach has on teaching science. And while these individuals eagerly embrace SENCER and revise courses to incorporate the SENCER approach, many face the arduous task of convincing their colleagues and administrators that SENCER is a worthwhile investment. Leading change in institutions steeped in tradition can be difficult, yet some institutions do have success in implementing SENCER throughout the STEM disciplines. This chapter discusses strategies which have proven successful in implementing SENCER at a public, comprehensive university and weaves together leadership and marketing theories which can lead to a tapestry of program and institutional change. © 2012 American Chemical Society.

Spectroscopy is often one of the most difficult subjects in an organic chemistry course for students to master. One difficulty comes from relating peaks in a spectrum with structural features. For example, when teaching infrared spectroscopy, it is often difficult to connect the theory between bending and stretching vibrations to the actual peaks. iSpartan for the iOS platform allows this to be done easily without the high cost of the full Spartan software. © 2014 The American Chemical Society and Division of Chemical Education, Inc.

Post examination self-assessment surveys were utilized to explore student performance on examinations in organic chemistry courses. This study of student self-perception looked at the application of the Kruger-Dunning effect in organic chemistry courses. The results include a comparison of student performance to expectations and the amount of time spent preparing. Results for poorer performing students indicate a lack of connectivity between perception and actual results. © 2014 American Chemical Society.

The excellent O-regioselectivity of the glycosidation of the ambident 2-O-substituted 5-fluorouracil (5-FU) via the silver salt method is computationally investigated at the MP2/6-311++G(2d,p):DZP//B3LYP/6-31+G(d):DZP level of theory. The reactions studied are those between 1-bromo-1-deoxy-2,3,4,6-tetra-O-acetyl-α-d-glucopyranose and the silver salts of 5-FU, 2-O-butyl-5-FU, and 2-O-benzyl-5-FU. Two pathways are considered as follows: (A) one where the silver and bromide ion do not interact, and (B) another where the silver and bromide ion interact in the transition states. Because the O-reaction barriers are much lower (by 13.3-22.2 kcal/mol) than N-reaction barriers in both pathways, the O-regioselectivity of the silver salt method can be satisfactorily explained by either path A or path B. Furthermore, path B, where Ag and Br interact consistently, has lower activation barriers than the corresponding path A (by 6.8-17.4 kcal/mol) in both N- and O-reactions. This computational result can be attributed to the following reasons: (1) the speeding-up effect in Koenigs-Knorr reactions due to the addition of silver carbonate into the reaction mixture; (2) the halogens being pulled away by silver ions from halides, as proposed by Kornblum and co-workers; and (3) the oxocarbenium ion involvement in the glycosidation reactions. The large energy difference between N- and O-transition states originates from the association between Ag and N-(O-) of the ambident unit (-N3-C4=O4) that shows significant covalent character so that the O-reaction transition states of the silver salt method benefit from favorable ionic interaction (C+···O-) and favorable covalent interaction (Ag···N). These two favorable interactions are in agreement with the hard and soft acids and bases principle; the former is a hard-hard interaction and the latter is a soft-soft interaction. © 2018 American Chemical Society.

The model reactions CH3X + (NH—CH=O)M ➔ CH3—NH—NH═O or NH═CH—O—CH3 + MX (M = none, Li, Na, K, Ag, Cu; X = F, Cl, Br) are investigated to demonstrate the feasibility of Marcus theory and the hard and soft acids and bases (HSAB) principle in predicting the reactivity of ambident nucleophiles. The delocalization indices (DI) are defined in the framework of the quantum theory of atoms in molecules (QT-AIM), and are used as the scale of softness in the HSAB principle. To react with the ambident nucleophile NH═CH—O−, the carbocation H3C+ from CH3X (F, Cl, Br) is actually a borderline acid according to the DI values of the forming C…N and C…O bonds in the transition states (between 0.25 and 0.49), while the counter ions are divided into three groups according to the DI values of weak interactions involving M (M…X, M…N, and M…O): group I (M = none, and Me4N) basically show zero DI values; group II species (M = Li, Na, and K) have noticeable DI values but the magnitudes are usually less than 0.15; and group III species (M = Ag and Cu(I)) have significant DI values (0.30–0.61). On a relative basis, H3C+ is a soft acid with respect to group I and group II counter ions, and a hard acid with respect to group III counter ions. Therefore, N-regioselectivity is found in the presence of group I and group II counter ions (M = Me4N, Li, Na, K), while O-regioselectivity is observed in the presence of the group III counter ions (M = Ag, and Cu(I)). The hardness of atoms, groups, and molecules is also calculated with new functions that depend on ionization potential (I) and electron affinity (A) and use the atomic charges obtained from localization indices (LI), so that the regioselectivity is explained by the atomic hardness of reactive nitrogen atoms in the transition states according to the maximum hardness principle (MHP). The exact Marcus equation is derived from the simple harmonic potential energy parabola, so that the concepts of activation free energy, intrinsic activation barrier, and reaction energy are completely connected. The required intrinsic activation barriers can be either estimated from ab initio calculations on reactant, transition state, and product of the model reactions, or calculated from identity reactions. The counter ions stabilize the reactant through bridging N- and O-site of reactant of identity reactions, so that the intrinsic barriers for the salts are higher than those for free ambident anions, which is explained by the increased reorganization parameter Δr. The proper application of Marcus theory should quantitatively consider all three terms of Marcus equation, and reliably represent the results with potential energy parabolas for reactants and all products. For the model reactions, both Marcus theory and HSAB principle/MHP principle predict the N-regioselectivity when M = none, Me4N, Li, Na, K, and the O-regioselectivity when M = Ag and Cu(I). © 2019 Wiley Periodicals, Inc. © 2019 Wiley Periodicals, Inc.

By focusing on food and a pervasive contaminant, this experiment engages student interest and effort while providing essential instruction and experience. As institutions are challenged by existing and emerging budgetary constraints, this experiment offers a determination approach employing commonly available instrumentation, the graphite furnace atomic absorption spectrometer. The module provides a broad range of experiences: it introduces the lyophilizer, offers practice in a multistep novel digestion method, presents the theoretical foundation and practical application of atomic absorption spectroscopy, and provides an opportunity to record, calculate, and report findings. Students whose math skills are in development can complete it successfully because algebraic calculations are used at each stage of the materials' examination. Finally, when their reports align with extensive international research, the lab offers students assurance of their growing scientific competence. © 2021 American Chemical Society and Division of Chemical Education, Inc.

We extrapolate to the perturbative triples (T)/complete basis set (CBS) limit using double zeta basis sets without polarization functions (Wesleyan-1-Triples-2zeta or "Wes1T-2Z") and triple zeta basis sets with a single level of polarization functions (Wesleyan-1-Triples-3zeta or "Wes1T-3Z"). These basis sets were optimized for 102 species representing the first two rows of the Periodic Table. The species include the entire set of neutral atoms, positive and negative atomic ions, as well as several homonuclear diatomic molecules, hydrides, rare gas dimers, polar molecules, such as oxides and fluorides, and a few transition states. The extrapolated Wes1T-(2,3)Z triples energies agree with (T)/CBS benchmarks to within +/-0.65 mEh, while the rms deviations of comparable model chemistries W1, CBS-APNO, and CBS-QB3 for the same test set are +/-0.23 mEh, +/-2.37 mEh, and +/-5.80 mEh, respectively. The Wes1T-(2,3)Z triples calculation time for the largest hydrocarbon in the G2/97 test set, C6H5Me(+), is reduced by a factor of 25 when compared to W1. The cost-effectiveness of the Wes1T-(2,3)Z extrapolation validates the usefulness of the Wes1T-2Z and Wes1T-3Z basis sets which are now available for a more efficient extrapolation of the (T) component of any composite model chemistry.