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The application of copolymer hydrogels based on acrylamide (AAm) and acrylic acid (AA) in sub-Saharan soils can increase the quantity of water retained by the soil and improve plant establishment and growth. The aim of this work was to synthesize and characterize a copolymer based on acrylamide and acrylic acid and to evaluate its swelling capacity with different physicochemical parameters. This study also aimed to investigate the effect of metallic cations on the swelling capacity of the copolymer and to assess the improvement in water retention in sandy soils. The copolymer material was prepared by free-radical polymerization in aqueous solution at a temperature of 60[degrees]C and characterized by Fourier transform infrared (FTIR) and x-ray diffraction (XRD), and its average molecular weight was estimated from intrinsic viscosity measurements. The swelling capacity was evaluated with different physicochemical parameters, and the effect of metallic cations on the swelling capacity was investigated. Water retention in two sandy soils was also evaluated. The copolymer material containing 50% AAm and 50% AA can retain more than 8100% of water. The swelling ratio increased with increasing temperature, with a maximum swelling ratio at 65[degrees]C. The presence of metallic cations reduced the maximum swelling ratio of the copolymer material as the cation concentration increased. The copolymer material at 1% in a composition with the soil showed an improvement in the water retention of 12.2% and 7.9% for soil A and 7.9% for soil B. Soil air volume is improved by 19% for both soils. This study shows that the copolymer material has a high swelling ratio and can improve water retention in sandy soils. The copolymer can be used in agriculture to protect and improve plant growth and yield. Highlights * Synthesis and characterization of a copolymer based on acrylamide and acrylic acid. * Evaluating the swelling capacity with different physicochemical parameters. * The application of this copolymer in sub-Saharan soils increases the quantity of water retained. * The copolymer is prepared by polymerization in aqueous solution and characterized by FTIR and XRD. * This study shows that the copolymer has a high swelling ratio and improves water retention. KEYWORDS hydrogel, poly(AAm-co-AA), soils, swelling, water retention, 1 | INTRODUCTION Hydrogels are networks of cross-linked polymers capable of absorbing and retaining large quantity of water. Their structures are heterogeneous in different orders of micromorphology. (1) Many methods [...]

In this study, polypropylene (PP) films containing the [beta] nucleating agent, N.N'-dicyclohexyl-2,6-naphthalenedicarboxamide, were prepared using PP with three different molecular weights (low, medium, and high) by extrusion process with T-shaped die. The structure and morphology of the films were studied after stretching. It was found that a unique molecular orientation, in which both the c-axis and crystalline lamellae were oriented perpendicular to the flow direction, was formed in all undrawn film samples, irrespective of the molecular weights of the PP. In the PP sheets stretched in the machine direction, the low-molecular-weight sample containing the nucleating agent exhibited brittle properties owing to a lack of tie chains in the stretching direction. In contrast, cavitation was prominent in the medium (M-PP)- and high (H-PP)-molecular-weight samples. Notably, M-PP containing the nucleating agent, with a high degree of molecular orientation, promoted the formation of a large number of voids. In H-PP containing the nucleating agent, the presence of numerous tie chains inhibited cavitation, resulting in fewer voids. The experimental results demonstrated the influence of the molecular weight on the void structure, which will be useful in the field of microporous membranes. KEYWORDS cavitation, molecular orientation, morphology, nucleation, polypropylene, 1 | INTRODUCTION With an increased demand for high-performance and specialized polymeric materials, polypropylene (PP)--which is one of the most versatile polymers for various applications owing to its good cost [...]

ABSTRACT. Fourier transform infrared spectroscopy (FTIR) was used to investigate the interactions between [C.sub.60] and [C.sub.70] molecules (nanoparticles in solutions) and dimethylacetamide, dimethylformamide, and acetamide using toluene as a solvent. [...]

Predicting the three-dimensional structure of a protein from its amino acid sequence requires a complete understanding of the molecular forces that influences the protein folding process. Each possible conformation has its corresponding potential energy, which characterizes its thermodynamic stability. This is needed to identify the primary intra- and intermolecular interactions, so that we can reduce the dimensionality of the problem, and create a relatively simple representation of the system. Investigating this problem using quantum chemical methods produces accurate results; however, this also entails large computational resources. In this study, an improved two-rotor potential energy function is proposed to represent the backbone interactions in amino acids through a linear combination of a Fourier series and a mixture of Gaussian functions. This function is applied to approximate the 20 amino acid diamide Ramachandran-type PESs, and results yielded an average RMSE of 2.36 kJ [mol.sup.-1], which suggest that the mathematical model precisely captures the general topology of the conformational potential energy surface. Furthermore, this paper provides insights on the conformational preferences of amino acid diamides through local minima geometries and energy ranges, using the improved mathematical model. The proposed mathematical model presents a simpler representation that attempts to provide a framework on building polypeptide models from individual amino acid functions, and consequently, a novel method for rapid but accurate evaluation of potential energies for biomolecular simulations. Key words: potential energy surface, conformational analysis, mathematical modeling. La prediction de la structure tridimensionnelle d'une proteine a partir de sa sequence d'acides amines requiert une parfaite comprehension des forces moleculaires qui influencent le processus de repliement des proteines. Chacune des conformations possibles possede sa propre energie potentielle, laquelle caracterise sa stabilite thermodynamique. Ces connaissances sont necessaires pour la determination des interactions primaires intra et intermoleculaires, de maniere a pouvoir reduire la dimensionnalite du probleme et creer une representation relativement simple du systeme. L'etude de ce probleme a l'aide de methodes de chimie quantique, bien que produisant des resultats exacts, necessite aussi des ressources informatiques considerables. Dans le cadre de la presente etude, nous proposons une fonction d'energie potentielle a deux rotors pour representer les interactions du squelette d'acides amines, par une combinaison lineaire d'une serie de Fourrier et d'un amalgame de fonctions gaussiennes. Nous avons applique cette fonction a l'approximation des surfaces d'energie potentielle (SEP) de type Ramachandran des 20 acides amines d'un diamide. Les resultats ont produit un ecart moyen quadratique de 2,38 kJ*[mol.sup.-1], ce qui laisse supposer que ce modele mathematique represente bien la topologie generale de sa surface d'energie potentielle conformationnelle. De plus, cet article fournit des informations sur les conformations preferentielles de diamides d'acides amines grace a la geometrie des minima locaux et aux intervalles energetiques obtenus au moyen de ce modele mathematique ameliore. Le modele mathematique que nous pro-posons offre une representation simplifiee en vue d'etablir un cadre pour la construction de modeles de polypeptides a partir des fonctions des acides amines qui le composent et, par consequent, constitue une nouvelle methode pour l'evaluation rapide et exacte des energies potentielles aux fins de modelisation de biomolecules. [Traduit par la Redaction] Mots-cles : surface d'energie potentielle, analyse conformationnelle, modelisation mathematique., Introduction Proteins, which are assembled from 20 amino acids, are machines and building blocks of living cells. The macromolecules are vital for structure, function, and regulation of various biological processes. [...]

Abstract: Vibrational and spectral characterizations of 2-(6-oxo-2-thioxo tetrahydro pyrimidin-4(lh)-ylidene) hydrazine carboxamide (OTHHPYHC) were experimentally presented for the ground state using FTIR and FT-Raman and theoretically presented by density functional theory [...]

Abstract: Interest in the low carbonyl IR frequency of 2-hydroxy-N,N-bis(2-hydroxyethyl)acetamide (2) initially prompted our interest in the amide rotational barrier of this molecule and four related amides that present a [...]

Abstract: High energetic materials tetranitroacetimidic acid (TNAA) and tetranitroacetamide (NTNAA) with positive oxygen balance (OB = 30%) are highly potential replacements for ammonium perchlorate (AP). Tautomerization from TNAA to NTNAA [...]

Abstract: Anomeric amides, RCON(X)(Y), have two electronegative atoms at the amide nitrogen, a configuration that results in greatly reduced amide resonance and strongly pyramidal nitrogen atoms. This, combined with facilitation [...]

In this study, P(NIPAAm-MAm)/A, which is a new smart polymer on which the temperature sensitivity of Nisopropyl acrylamide monomer and pH sensitivities of methacrylic acid (MA) and itaconic acid (IA) monomers unite, were prepared by free radical polymerization. The influence of crosslinkers on the properties of polymer and adsorption was studied using two different crosslinkers. These new environmentally multistimuli responsive hydrogels were characterized by FTIR, TG, and DSC. In order to determine the swelling behaviors of polymers, the equilibrium swelling studies were carried out at different temperatures and pHs. With the aim of studying the usability of the prepared polymers in the adsorption of nicotine and its pharmaceutical derivatives, the effects of temperature, pH, and adsorbent mass on adsorption equilibrium were Studied., INTRODUCTION Nicotine is an alkaloid present in several plants, but its major source is tobacco, used for cigarette manufacture. Nicotine is a highly toxic compound: 40-60 mg can be a [...]

An approach is proposed to the estimation of the total concentration of sulfonamides in milk based on their adsorption isolation and preconcentration from whole milk with magnetic hypercrosslinked polystyrene followed by the spectrophotometric determination in an acetonitrile eluate by the reaction with p-dimethylaminocinnamaldehyde. The procedure was used for the determination of the total concentration of sulfonamides in milk at a level of the maximum residue limits. Keywords: sulfonamides, milk, magnetic solid-phase extraction, magnetic hypercrosslinked polystyrene, spectrophotometry, Sulfonamides (SA) are among the most commonly used veterinary products along with tetracyclines, fluoroquinolones, and [beta]-lactam antibiotics [1]. Because of a wide spectrum of pharmacological action and low cost, SA [...]

Note: Below is an excerpt from Chapter 19 of the book Monitoring Polymerization Reactions: From Fundamentals to Applications, ed. by Wayne F. Reed and Alina M. Alb (2014, John Wiley [...]

A novel cyanide analyzer based on sensitive cobinamide chemistry relies on simultaneous reagent and sample injection and detection in a 50 cm liquid core waveguide (LCW) flow cell illuminated by a white light emitting diode. 0The transmitted light is read by a fiber-optic charge coupled device (CCD) spectrometer. Alkaline cobinamide (orange, [lambda].sub.max] = 510 nm) changes to violet ([[lambda].sub.max]] = 583 nm) upon reaction with cyanide. Multiwavelength detection permits built-in correction for artifact responses intrinsic to a single-line flow injection system and corrects for drift. With optimum choice of the reaction medium, flow rate, and mixing coil length, the limit of detection (LOD, S/N = 3) is 30 nM and the linear dynamic range extends to 10 [micro]M. The response base width for 1% carryover is this can be corrected for. We demonstrate applicability by analyzing the hydrolytic cyanide extract of apple and pear seeds with orange seeds as control and also measure HCN in breath air samples. Spike recoveries in these sample extracts ranged from 91 to 108%. 10.1021/ac101158d

Identifying points of control in inflammation is essential to discovering safe and effective antiinflammatory medicines. Palmitoylethanolamide (PEA) is a naturally occurring lipid amide that, when administered as a drug, inhibits inflammatory responses by engaging peroxisome proliferator-activated receptor-[alpha] (PPAR-[alpha]). PEA is preferentially hydrolyzed by the cysteine amidase Nacylethanolamine-hydrolyzing acid amidase (NAAA), which is highly expressed in macrophages. Here we report the discovery of a potent and selective NAAA inhibitor, N-[(3S)-2-oxo-3-oxetanyl]3-phenylpropanamide [(S)-OOPP], and show that this inhibitor increases PEA levels in activated leukocytes and blunts responses induced by inflammatory stimuli both in vitro and in vivo. These effects are stereoselective, mimicked by exogenous PEA, and abolished by PPAR-[alpha] deletion. (S)-OOPP also attenuates inflammation and tissue damage and improves recovery of motor function in mice subjected to spinal cord trauma. The results suggest that PEA activation of PPAR-[alpha] in leukocytes serves as an early stop signal that contrasts the progress of inflammation. The PEA-hydrolyzing amidase NAAA may provide a previously undescribed target for antiinflammatory medicines. NAAA | oleoylethanolamide | PPAR-[alpha] doi/10.1073/pnas.0907417106

Amide hydrogen/deuterium exchange (H/DX) measurements by mass spectrometry provide a powerful tool for probing the structure and dynamics of proteins. In order to extend such measurements to complex multiprotein systems, new methods for delivering higher sensitivity and sequence coverage are required. In this study, we investigated the utility of tandem mass spectrometry (MS/MS) for providing an alternative to the conventional MS mode of operation applied to bottom-up H/DX experiments. Specifically, we aimed to determine whether differential deuteration measurements of collisionally induced dissociation (CID)-generated product ions can serve as effective surrogates for their corresponding intact peptide, thus providing an additional dimension for analysis. Replicate deuterium measurements of calmodulin (in its apo and holo forms) were obtained from peptic digests in both the MS and MS/MS domains and studied as a function of % deuteration, fragment ion selection, and contaminant level. We show that successful acquisition of MS/MS data for deuterated peptides requires controlled expansion of the isotopic envelope by limiting the range of deuterium label applied in the exchange-in reaction ([less than or equal to] 50%) and that automation of ion selection via data-dependent acquisition is ultimately dependent upon peak detection algorithms. Upon full transmission of the isotopic envelope, fragment data demonstrate that all ions, with the exception of neutral loss fragment ions, return deuteration ratios reflecting the apo/holo transition that ate in general agreement with values obtained from the corresponding precursor ions. The agreement is limited primarily by the ion statistics for each fragment, as the base peak in the MS/MS spectra provided the best correlation regardless of its m/z. We highlight that the freedom to select the base peak as a surrogate for the precursor ion derives from extensive H/D scrambling inducible under conventional CID conditions. When spectral interference prohibits conventional H/DX-MS measurements, we further show that the surrogate approach recovers accurate and precise per-peptide deuteration levels. Thus, a generalized strategy is presented in which CID-based automated H/DX-MS/MS acquisition can be used to extend measurements to complex protein systems, exceeding the peptide capacity of conventional H/DX-MS alone.

Epoxidized diethanolamides were synthesized by reacting diethanolamine (DEA) with mixture of Epoxidized Palm Olein ([EPO.sub.o] 40% w/w) and Refined Bleached Deodorized Palm Kernel Olein ([RBDPKO.sub.o], 60% w/w) at 1:3 molar at 80[degrees]C for 5 h and continued at 110[degrees]C for another 4 h of reaction time. Synthesized diethanolamides with high content of epoxides were reacted with isocyanate in the presence of [AlCl.sub.3]-THF complex catalyst to produce oxazolidone linkages in polyurethane network. The rigid polyurethane foam produced is of better quality as compared to the commercially available foam. Key words: Amine value, epoxidized diethanolamides, FTIR, hydroxyl value, oxirane oxygen contents, INTRODUCTION Alkanolamides is an important non-ionic surfactant using in the household products, personal care and cosmetic industries. Fatty alkanolamides, namely monoalkanolamide and dialkanolamide can be prepared by reacting fatty acids [...]

Pilin precursors are the building blocks of pill on the surface of Gram-positive bacteria; however, the assembly mechanisms of these adhesive fibers are unknown. Here, we describe the chemical bonds that assemble BcpA pilin subunits on the surface of Bacillus cereus. Sortase D cleaves BcpA precursor between the threonine (T) and the glycine (G) residues of its LPXTG sorting signal and catalyzes formation of an amide bond between threonine (T) of the sorting signal and lysine (K) in the YPKN motif of another BcpA subunit. Three CNA B domains of BcpA generate intramolecular amide bonds, and one of these contributes also to pilus formation. Conservation of catalysts and structural elements in pilin precursors in Gram-positive bacteria suggests a universal mechanism of fiber assembly. CNA B domain | LPXTG sorting signal | sortase | YPKN motif

A new method is described by using an amide ligation reaction for the characterization of acyl carrier protein (ACP)-bound reaction intermediates. This novel method has characterized the ACP-mediated biosynthesis of the unique 2,3-epoxyhexanoyl moiety of calcium-dependent antibiotic (CDA), which has disclosed a new type of FAD-dependent oxidase HxcO with enoyl-ACP epoxidase activity, as well as a second enoyl-ACP epoxidase, HcmO.

The temperature and length scale dependence of tetraalkylammonium salt-amide interaction in water are investigated. The interaction increases with an increase in cation size till a maximum is reached, after which the reverse trend is observed, as water is unable to maintains its H-bond network around the large tetraalkylammonium cation.

An efficient and high-yielding method for the asymmetric synthesis of calcimimetic ()-NPS R-568 drug is reported. The synthesis involves highly diastereoselective addition of methyl Grignard to the ([S.sub.s],E)-N-(3-methoxybenzylidene)-2-propanesulfinamide [5(S)].

The molecular structure, infrared spectra, and UV-induced photochemistry of picolinamide (PA) and isonicotinamide (INA) isolated in cryogenic inert matrixes are described. Both PA and INA exist in a single conformation in cryogenic rare distinct matrix sites.

Stabilities and conformational properties of two Pro related to Thr point mutation models are computed at the B3LYP/6-31 G(d) level of theory for the parent triamino acid diamide Pro-Pro-Pro (HCO-Pro-Pro-Pro-N[H.sub.2]). Study describes an approach to analyzing a point mutation at the center of a peptide chain.

The effects of different surfactant solutions on the photophysics of various watersoluble perylene diimides (WS-PDIs) are studied. The surfactants are found to increase the fluorescence quantum yield and lifetime of these WS-PDIs.

A study was conducted to generate enols where Y,Y' were two dialkoxyphosphinyl [(RO).sub.2]P=O groups or a combination of [(RO).sub.2]P=O and [CO.sub.2]R or CN. The O=P[(OR').sub.2] substituent was found to be suitable activator for enolization as no competing enolization was observed on the P=O group.

The calculation results of the coupling between all amide fundamentals and their overtones and combination vibrational states are presented.

The various amide-silyl ligand exchanges and equilibria that exist among the group 4 amide and silyl complexes are explained. The analysis reveals that most of these silyl complexes are prepared by replacing the halide ligands in the M-X complexes by silyl atoms.

A practical, safe and general method is described that has used a combination of diisopropylethylamine and sodium tert-butoxide. This method has allowed for preparing 4-hydroxyquinolinone esters and amides in good yields.

The synthesis of a fused bicyclic C-glucosylproline hybrid (GlcProH) from 2,3,4,6-tetra-O-benzyl-D-glucopyranose is described. The GlcProH has shown variation in the prolyl N-terminal amide equilibrium through tuning of the carbohydrate scaffold, which is a new concept in proline peptidomimetics.

The results of the theoretical calculations of formamide and urea hydrolysis at different pH values are presented.

The syntheses and characterization of the iron(II) complexes of the pentadentate amide-containing macrocyclic ligand 3,6,9,12,18-pentaazabicyclo-[12,3,1]octadeca-1(18),14,16-triene-2,13-dione ([H.sub.2]pydione[N.sub.5]) are reported. The complexes maintain a high-spin state even at low temperature and detailed kinetic studies of oxygenation of the iron(II) complexes showed that the deprotonation state of the complex has a profound effect on the reactivity with dioxygen.

Tertiary aryl squaramides are synthesized by using copper-catalyzed C-N bond-formation with L-proline as the ligand. Symmetrical diaryl squaramides are prepared by using excess aryl bromide and unsymmetrical derivatives are prepared by sequential arylation, where the diarylated products are highly sensitive to steric effects.

The first sequential one-pot double dearomatization of bis(N-benzyl-P,P-diphenylphosphinamides) is described via an anionic cyclization. The analysis provides a facile route of accessing the multifunctional systems with the antitumor properties, as the doubly phosphorylated systems prove to be active against a series of cancer line cells.

A study is conducted to find how the degrees of hydration might affect the amide I' vibrational transitions of two alanine-based helical peptides and how it affects their aggregation behaviors. The results show that the dehydrated helical amide groups give rise to an amide I' band centered around approximately 1650 [cm.sup.-1], whereas hydration shifts this band toward lower frequencies.

The vibrational interactions between adjacent peptide units are studied in the peptide bond angles of neutral trialanine. The amide I vibrations show a strong coupling in [alpha]-helical conformation than in PPII conformation of trialanine.

A nearly isosteric photosensitive amide-backbone substitution, which helps in the switching of the activities in the ribonuclease S complex is demonstrated. The complete abolishing of the enzymatic activity of the complex after its recovery from reisomerization proves that the thioxopeptide bond modified polypeptide backbone can be widely used in photoswitching of proteins.

A simple atom-replacement approach for estimating the individual contributions of each intermolecular hydrogen bond (HB) in multiple hydrogen-bonded systems is described. The method is found to be helpful in distinguishing the relative strength of each HB, and identify the main factors contributing to the total binding energies of multiple HBs.

p-Toluenesulfonamide (p-TsN[H.sub.2] or tosyl) is used as an imido ligand precursor in the synthesis of highly air- and moisture-sensitive titanium(IV) and vanadium(IV) complexes. The structural analysis has shown the electron-deficient character of the tosylimido group along with highly structural diversity for the complexes bearing the tosylimide function.

A new ligand, 8[O.sub.2] 1,4,7,10-tetraazadodecane tetraacetic acid (DOTAM), is synthesized and its lanthanide complexes are examined as potential chemical exchange saturation transfer (CEST) agents. The analysis reveals that the increasing ionic radius of the lanthanide ion leads to an increase in the extent of the distortion, thereby leading to a complete loss of symmetry in the complex.

9-Formyljulolidine is oxidized by using a microwave-assisted Willgerodt-Kindler reaction to the N-piperidine or N-morpholine julolidine-9-thioamide. The products are converted to chalcogenoxanthones with phosphorus oxychloride and triethylamine (PO[Cl.sub.3]/[Et.sub.3]N).

Gas electron diffraction (GED) and quantum chemical calculations were used to investigate the geometric structure of malonamide, N[H.sub.2]C(O)-C[H.sub.2]-C(O)N[H.sub.2]. Both GED and quantum chemistry result in the existence of a single diketo conformer in the gas phase which possesses one C=O bond in synclinal orientation and the other C=O bond in anticlinal orientation.

The usefulness and limitations of [Cp.sub.2]Zr(H)Cl (Schwartz's reagent) to reduce a wide range of tertiary amides to the corresponding aldehydes under very mild reaction conditions and in high yields is analyzed. The intermediate for the reduction is characterized and the possible methods for the formation of the intermediate and the aldehyde products are described.

A general and effective one-step procedure is presented for the synthesis of [beta]-sulfonamidodisulfides directly from N-tosyl aziridines in a regio- and stereospecific manner under neutral conditions and without using any Lewis acid or base. A number of [beta]-sulfonamidosulfides are synthesized in tandem, multistep reactions.

Density functional theory and ab initio methods are used to study the mechanisms for the hydrolysis of N-(2-oxo-1,2-dihydro-pyrimidinyl) formamide (PFA) in the gas phase. The results have shown that the solvent water slightly reduces the energy barrier in each pathway, but the first pathway in the water-assisted hydrolysis has remained the most favorable when the solvent effects of bulk water are taken into account.

Complete basis set calculations (CBS-QB3) are used to compute the CN rotation barriers for acetamide and eight related compounds, including acetamide enolate and O-protonated acetamide. The resonance explanation for high CN rotation barriers is more consistent than the competing polarization model.

The first asymmetric total syntheses of the dihalogenated medium-sized dioxabicyclic marine natural products (+)-(3)-(Z)-isolaureatin and (+)-3-(Z)-laureatin are carried out. Significant features of the highly stereo-, region, and chemoselective syntheses of these [alpha],[alpha]'-trans-oxocene natural products include an intramolecular amide enolate alkylation to construct the [alpha],[alpha]'-cis-oxocene, and new olefin cross-metatheses for construction of the (Z)-enyne systems.

The calculations based on the density functional theory (DFT) are used to investigate and analyze the various effects of aqueous solvents on the infrared (IR) and vibrational circular dichroism (CD) spectra of the partially solvated [alpha]-helices. The results show that the amide band-shapes highly depend on the extent of solvation of the helix and the side of contact with the solvent, which shows that the effects of solvation vary from case to case and hence must be studied separately.

The synthesis and structural properties of novel boron and aluminum complexes having the tripodal triamido [[N.sub.3].sup.3-] ligand framework are described. The trigonal pyramidal geometry at B in the tripodal triamido borane structure due to the lack of significant N-B p-p [pi]-interactions suggests significant Lewis acidity imposed by the geometry within the tripodal triamido binding pocket.