Decomposition of a complete multigraph into simple paths: Nonbalanced handcuffed designs

The condition λv(v ? 1) ≡ 0 (mod 2m), v ? m + 1 is obviously necessary for the existence of an edge disjoint decomposition of a complete multigraph λK_v into isomorphic simple paths consisting of m edges each. This condition is proved here to be sufficient. The proof is also valid in some cases when the given paths are not necessarity of the same length.     

S3O and S3O+ in the gas phase: Ring and open-chain structures

Ring and open-chain S3O sulfur oxides are detected by neutralization-reionization experiments.     

Optimal Sobolev Type Inequalities in Lorentz Spaces

It is well known that the classical Sobolev embeddings may be improved within the framework of Lorentz spaces L ^p,q : the space $\mathcal{D}^{1,p}(\mathbb R^n)$ , 1?<?p?<?n, embeds into $L^{p^*,q}(\mathbb R^n)$ , p?≤?q?≤?∞. However, the value of the best possible embedding constants in the corresponding inequalities is known just in the case $L^{p^*,p}(\mathbb R^n)$ . Here, we determine optimal constants for the embedding of the space $\mathcal{D}^{1,p}(\mathbb R^n)$ , 1?<?p?<?n, into the whole Lorentz space scale $L^{p^{\ast}, q}(\mathbb R^n)$ , p?≤?q?≤?∞, including the limiting case q?=?p of which we give a new proof. We also exhibit extremal functions for these embedding inequalities by solving related elliptic problems.     

γ-Valerolactone (GVL) as a green and efficient dipolar aprotic reaction medium

The great challenge for modern research is to define the most efficient tools to make more sustainable the industrial production and manufacturing. Among the different aspects that require attention the replacement of toxic and/or non-renewable solvents it is certainly playing a crucial role. Dealing with widely used dipolar aprotic solvents, among the different alternatives proposed in the literature γ-valerolactone (GVL) plays a pivotal role covering different application area. In this contribution, the benefits derived from the use of GVL as a circular, safe, biomass-derived reaction medium are highlighted covering most recent publications (2021). The presentation has been divided into three major sections: (i) biomass valorization, (ii) materials synthesis, manufacturing and recycle and (iii) new synthetic methodologies.     

Antimicrobial Effect and Cytotoxic Evaluation of Mg-Doped Hydroxyapatite Functionalized with Au-Nano Rods

Hydroxyapatite (HA) is the main inorganic mineral that constitutes bone matrix and represents the most used biomaterial for bone regeneration. Over the years, it has been demonstrated that HA exhibits good biocompatibility, osteoconductivity, and osteoinductivity both in vitro and in vivo, and can be prepared by synthetic and natural sources via easy fabrication strategies. However, its low antibacterial property and its fragile nature restricts its usage for bone graft applications. In this study we functionalized a MgHA scaffold with gold nanorods (AuNRs) and evaluated its antibacterial effect against S. aureus and E. coli in both suspension and adhesion and its cytotoxicity over time (1 to 24 days). Results show that the AuNRs nano-functionalization improves the antibacterial activity with 100% bacterial reduction after 24 h. The toxicity study, however, indicates a 4.38-fold cell number decrease at 24 days. Although further optimization on nano-functionalization process are needed for cytotoxicity, these data indicated that Au-NRs nano-functionalization is a very promising method for improving the antibacterial properties of HA.     

Development and application of electrochemical sensor of boron-doped diamond (BDD) modified by drop casting with tin hexacyanoferrate

Journal of Solid State Electrochemistry - This work presents the development and characterization of an electrochemical sensor of tin hexacyanoferrate (SnHCF), produced from the modification by...     

A Jocic-type approach for a practical and scalable synthesis of pyrrolonaphthoxazepine (PNOX)-based potent proapoptotic agents

We developed a Jocic-type protocol for the construction of the pyrrolonaphthoxazepine (PNOX) core. After an initial investigation based on the isolation of a trichloromethyl carbinol derivative, we shifted our attention towards a multicomponent single-step protocol. Screening of a variety of bases and solvents led to the identification of the optimum conditions for the preparation of the key α-aryloxy carboxylic acids to undergo intramolecular cyclization. The novel chemical route significantly improved overall yields for the preparation of PNOX-based compounds and was successfully extended to the preparation of 1,4-benzoxazinone-based templates.     

Asymmetric synthesis and structure-activity studies of the fungal metabolites colletorin A,colletochlorin A and their halogenates analogues

The first asymmetric total synthesis of both enantiomers of the natural products colletorin A and colletochlorin A is presented. The proposed methodology is based on the coupling reaction between highly substituted aromatic Gilman cuprates and optically active allyl bromides, in turn obtained by Sharpless asymmetric dihydroxylation. The latter ensured a high degree of regio- and stereocontrol in the enantioselective step of the synthesis. The same synthetic strategy has been also applied for the preparation of differently halogenated synthetic analogues of colletochlorin A in high enantiomeric purity. The enantioselective synthesis of colletorin A and colletochlorin A allows to reliably assign their absolute configuration. Preliminary assessment of their herbicidal and insecticidal properties evidence the possibility to modulate the bioactivity of these compounds, highlighting its dependence on both the absolute stereochemistry and the halogen nature.     

Vibrational analysis of amino acids and short peptides in hydrated media. 3. Successive KL repeats induce highly stable beta-strands capable of forming non-H-bonded aggregates

Circular dichroism (CD) and Raman scattering were applied to the aqueous solution of minimalist LK peptides constructed with successive KL repeats leading to the following generic primary sequence: (KL)nK. Three peptides of this family, a 3-mer (n=1), a 9-mer (n=4), and a 15-mer (n=7), are analyzed in this report. Raman spectra of the 3-mer (KLK, a random chain) and its labile-hydrogen deuterated species yield a set of interesting information for analyzing longer peptides of this series. Although the CD spectrum of the 9-mer (KLKLKLKLK) reveals a signal traditionally assigned to a random structure, the corresponding Raman spectrum allows finding a mixture of conformations in solution, adopting predominantly beta-type structures. This fact proves the utility of Raman spectroscopy to eliminate eventual ambiguity concerning conformational assignments in peptides based only on the use of CD technique. Finally, the 15-mer (KLKLKLKLKLKLKLK) gives rise to CD and Raman spectra clearly assignable to a beta-type structure. On the basis of all the observed results on the 15-mer, we can confirm that this peptide may exist as isolated beta-strands at low concentration (sub-micromolar), flat-oriented at the air/water interface, whereas at high concentrations (millimolar), non-H-bonded immersible aggregates might be formed. A hypothetical model for these beta-strand aggregates could be proposed as stabilized by an interior hydrophobic core and a hydrophilic external face, formed by leucine and lysine side chains, respectively.