Tritordeum, a hybrid cereal with a highly tricin-enriched lignin.

The lignin from tritordeum straw, a hybrid cereal from crossbreeding of durum wheat and wild barley, was isolated and chemically characterized. Its composition and structure were studied by analytical pyrolysis (Py-GC/MS), nuclear magnetic resonance spectroscopy (NMR), Derivatization Followed by Reductive Cleavage (DFRC) method, and gel permeation chromatography (GPC). The data revealed an enrichment of guaiacyl (G) units (H:G:S of 3:61:36), which had a significant impact on the distribution of inter-unit linkages.

Variations in the composition and structure of the lignins of oat (Avena sativa L.) straws according to variety and planting season.

The differences in the composition and structure of the lignins from straws of different oat (Avena sativa L.) varieties, planted in two seasons (winter and spring), were studied in detail by different analytical techniques such as pyrolysis coupled to gas chromatography-mass spectrometry (Py-GC/MS), two-dimensional nuclear magnetic resonance (2D-NMR), derivatization followed by reductive cleavage (DFRC), and gel permeation chromatography (GPC). Overall, the analyses revealed that oat straw lignins were enriched in guaiacyl (G; 50-56 %) and syringyl (S; 39-44 %) units, with relatively lower amounts of p-hydroxyphenyl (H; 4-6 %) units.

Structural Characterization of the Milled-Wood Lignin Isolated from Sweet Orange Tree () Pruning Residue.

The pruning of sweet orange trees () generates large amounts of lignocellulosic residue. Orange tree pruning (OTP) residue presents a significant lignin content (21.2%).

Introduction to Pharmaceutical Co-amorphous Systems Using a Green Co-milling Technique.

The concept of co-amorphous systems is introduced in an integrated laboratory experiment, designed for advanced chemistry students, using solvent-free, environmentally friendly mechanochemistry. The dual-drug naproxen-cimetidine co-amorphous system (NPX-CIM) is investigated as an example of the emergent field of medicinal mechanochemistry. Students are trained in solid-state characterization techniques including X-ray powder diffraction, Fourier-transform infrared spectroscopy, and thermal analysis by differential scanning calorimetry.

Dual Photochemistry of Benzimidazole.

Monomers of benzimidazole trapped in an argon matrix at 15 K were characterized by vibrational spectroscopy and identified as 1-tautomers exclusively. The photochemistry of matrix-isolated 1-benzimidazole was induced by excitations with a frequency-tunable narrowband UV light and followed spectroscopically. Hitherto unobserved photoproducts were identified as 4- and 6-tautomers.

Chemical composition of the lipophilic compounds from the rind and pith of papyrus ( L.) stems.

Papyrus ( L.) is a sedge plant with a high rate of biomass productivity that represents an interesting raw material to produce chemicals, materials and fuels, which are currently still obtained from fossil resources, in the context of a lignocellulosic biorefinery. In this work, the content and chemical composition of the lipids present in papyrus stems were thoroughly studied.

Chemical Composition of Lipophilic Compounds From Rice () Straw: An Attractive Feedstock for Obtaining Valuable Phytochemicals.

Rice ( L.) straw is a highly abundant, widely available, and low cost agricultural waste that can be used as a source to extract valuable phytochemicals of industrial interest. Hence, in the present work, the chemical composition of the lipophilic compounds present in rice straw was thoroughly characterized by gas chromatography and mass spectrometry using medium-length high-temperature capillary columns, which allowed the identification of a wide range of lipophilic compounds, from low molecular weight fatty acids to high molecular weight sterols esters, sterol glucosides, or triglycerides in the same chromatogram.

Dihydrofolate Reductase Inhibitors: The Pharmacophore as a Guide for Co-Crystal Screening.

In this work, co-crystal screening was carried out for two important dihydrofolate reductase (DHFR) inhibitors, trimethoprim (TMP) and pyrimethamine (PMA), and for 2,4-diaminopyrimidine (DAP), which is the pharmacophore of these active pharmaceutical ingredients (API). The isomeric pyridinecarboxamides and two xanthines, theophylline (THEO) and caffeine (CAF), were used as co-formers in the same experimental conditions, in order to evaluate the potential for the pharmacophore to be used as a guide in the screening process. In silico co-crystal screening was carried out using BIOVIA COSMOquick and experimental screening was performed by mechanochemistry and supported by (solid + liquid) binary phase diagrams, infrared spectroscopy (FTIR) and X-ray powder diffraction (XRPD).

Flavonoids naringenin chalcone, naringenin, dihydrotricin, and tricin are lignin monomers in papyrus.

Recent studies demonstrate that several polyphenolic compounds produced from beyond the canonical monolignol biosynthetic pathways can behave as lignin monomers, participating in radical coupling reactions and being incorporated into lignin polymers. Here, we show various classes of flavonoids, the chalconoid naringenin chalcone, the flavanones naringenin and dihydrotricin, and the flavone tricin, incorporated into the lignin polymer of papyrus (Cyperus papyrus L.) rind.

Lignin Quantification of Papyri by TGA-Not a Good Idea.

Papyri belong to the oldest writing grounds in history. Their conservation is of the highest importance in preserving our cultural heritage, which is best achieved based on an extensive knowledge of the materials' constituents to choose a tailored conservation approach. Thermogravimetric Analysis (TGA) has been widely employed to quantify cellulose and lignin in papyrus sheets, yielding reported lignin contents of 25% to 40%.

Structural Characteristics of the Guaiacyl-Rich Lignins From Rice ( L.) Husks and Straw.

Rice ( L.) is a major cereal crop used for human nutrition worldwide. Harvesting and processing of rice generates huge amounts of lignocellulosic by-products such as rice husks and straw, which present important lignin contents that can be used to produce chemicals and materials.

Vibrationally Induced Conformational Isomerization and Tunneling in Pyrrole-2-Carboxylic Acid.

The conformational behavior of carboxylic acids has attracted considerable attention, as it can be used as a gateway for the study of more complex phenomena. Here, we present an experimental and computational study of pyrrole-2-carboxylic acid (PCA) conformational space and the vibrational characterization of the compound by infrared spectroscopy. The possibility of promoting conformational transformations using selective vibrational excitation of the 2ν(OH) and 2ν(NH) stretching overtones is explored.

UV-induced radical formation and isomerization of 4-methoxyindole and 5-methoxyindole.

Monomers of 4-methoxyindole and 5-methoxyindole trapped in low-temperature xenon matrices (15-16 K) were characterized by IR spectroscopy, in separate experiments. Each compound was shown to adopt the most stable 1H-tautomeric form. The photochemistry of the matrix-isolated compounds was then investigated by exciting the matrices with narrowband UV light with λ ≤ 305 nm.

Effect of muscle density in patients with metastatic prostate cancer administered androgen deprivation therapy.

Introduction: Sarcopenia is a syndrome characterized by the loss of muscle mass and strength. The study objective was to determine the association between muscle density and overall survival (OS) in patients with metastatic onset prostate cancer (MPCa).

Materials And Methods: This was a retrospective study of patients diagnosed with MPCa between 2009 and 2015 who received androgen deprivation therapy alone as initial treatment.

Effects of aging under field conditions on biochar structure and composition: Implications for biochar stability in soils.

The effects of aging on biochar (BC) properties, composition and carbon sequestration are still under debate. This study aimed at illustrating the qualitative alterations of five different BCs aged during a 24-month field experiment located in Southwest Spain. To determine the recalcitrance of each BC, physical fragmentation test, scanning electron microscopy, C NMR spectroscopy and CO-respiration experiments were performed.

Synthesis of new metalloporphyrin triads: efficient and versatile tripod optical sensor for the detection of amines.

Zinc and manganese complexes of porphyrin triads have been synthesized and are shown to be efficient as highly sensitive and selective tripod optical sensors for amines at the picomolar level.

Conformational cooling dynamics in matrix-isolated 1,3-butanediol.

The complete conformational space of monomeric 1,3-butanediol has been characterized theoretically, and 73 unique stable conformers were found at the MP2/6-311++G(d,p) level. These were classified into nine families whose members share the same heavy atom backbone configurations and differ in the hydrogen atom orientations. The first and third most populated backbone families are governed by the formation of an intramolecular hydrogen bond; however, the second precludes this type of interaction and was frequently overlooked in previous studies.

Structure of isolated 1,4-butanediol: combination of MP2 calculations, NBO analysis, and matrix-isolation infrared spectroscopy.

Theoretical calculations at the MP2 level, NBO and AIM analysis, and matrix-isolation infrared spectroscopy have been used to investigate the structure of the isolated molecule of 1,4-butanediol (1,4-BDO). Sixty-five structures were found to be minima on the potential energy surface, and the three most stable forms are characterized by a folded backbone conformation leading to the formation of an intramolecular H-bond. To better characterize the intramolecular interactions and particularly the hydrogen bonds, natural bond orbital analysis (NBO) was performed for the four most stable conformers, and was further complemented with an atoms-in-molecules (AIM) topological analysis.

Hydration of cyclohexylamines: CPCM calculation of hydration Gibbs energy of the conformers.

This work presents a theoretical study on the hydration of cyclohexylamine and isomers of cyclohexyldiamine. All possible conformers were fully optimized in solution using the conductor-like polarizable continuum model (CPCM) and density functional theory. Values of the Gibbs energy of solvation, its respective contributions (electrostatic, nonelectrostatic and conformational change), and the relative Gibbs energy of the conformers in aqueous solution and gas phase are reported.

Stepwise conformational cooling towards a single isomeric state in the four internal rotors system 1,2-butanediol.

The present work explores the possibilities of the matrix isolation technique in the structural characterisation of highly flexible molecules. To date, most studies of this type were carried out on molecules with three or less internal degrees of freedom and a few (less than 10) possible conformations. The molecule of 1,2-butanediol has four conformationally relevant three-fold rotational axes, which can result in 81 possible conformations.

Conformational study of monomeric 2,3-butanediols by matrix-isolation infrared spectroscopy and DFT calculations.

The FT-IR spectra of two diastereomers of 2,3-butanediol, (R,S) and (S,S), isolated in low-temperature argon and xenon matrixes were studied, allowing the identification of two different conformers for each compound. These conformers were characterized by a +/-gauche arrangement around the O-C-C-O dihedral angle, thus enabling the establishment of a very weak intramolecular hydrogen bond of the O..

Conformational study of erythritol and threitol in the gas state by density functional theory calculations.

Density functional theory calculations using the B3LYP functional and the 6-311++G(d,p) basis set were carried out on the isolated molecules of erythritol and L-threitol. For the meso isomer, a relatively large number of conformers have to be considered to describe the gas state structure. The lowest energy conformer is characterized by the establishment of a strong intramolecular H-bond between the two terminal hydroxyl groups, giving rise to a seven-membered ring and two additional weaker H-bonds between vicinal OH groups.