Combustion Behavior of Cellulose Ester Fibrous Bundles from Used Cigarette Filters: Kinetic Analysis Study.

This study is focused on the detailed examination of the combustion properties and kinetic analysis of a cellulose acetate fibrous bundle (CAFB), separated from used cigarette filters. It was shown that the faster rate of CAFB heating allows a large amount of heat to be supplied to a combustion system in the initial stages, where the increase in heating rate has a positive response to ignition behavior. The best combustion stability of CAFB is achieved at the lowest heating rate. Through the use of different kinetic methods, it was shown that combustion takes place through two series of consecutive reaction steps and one independent single-step reaction. By optimizing the kinetic parameters within the proposed reaction models, it was found that the steps related to the generation of levoglucosenone (LGO) (by catalytic dehydration of levoglucosan (LG)) and acrolein (by breakdown of glycerol during CAFB burning-which was carried out through glycerol adsorption on a TiO2 surface in a the developed dehydration mechanism) represent rate-controlling steps, which are strongly controlled by applied heating rate. Isothermal predictions have shown that CAFB manifests very good long-term stability at 60 °C (which corresponds to storage in a sea shipping container), while at 200 °C, it shows a sudden loss in thermal stability, which is related to the physical properties of the sample.

Structures and growth pathways of AunCln+3- (n ≤ 7) cluster anions.

Gold chloride clusters play an important role in catalysis and materials chemistry. Due to the diversity of their species and isomers, there is still a dearth of structural studies at the molecular level. In this work, anions of AunCln+3 - and AunCln+5 - (n = 2-4) clusters were obtained by laser desorption/ionization mass spectrometry (LDI MS), and the most stable isomers of AunCln+3 - were determined after a thorough search and optimization at the TPSSh/aug-cc-pVTZ/ECP60MDF level. The results indicate that all isomers with the lowest energy have a planar zigzag skeleton. In each species, there is one Au(III) atom at the edge connected with four Cl atoms, which sets it from the other Au(I) atoms. Four growth pathways for AunCln+3 - (n = 2-7) clusters are proposed (labelled R1, R2, R3 and R4). They are all associated with an aurophilic contact and are exothermic. The binding energies tend to stabilize at ∼ -41 kcal/mol when the size of the cluster increases in all pathways. The pathway R1, which connects all the most stable isomers of the respective clusters, is characterized by cluster growth due to aurophilic interactions at the terminal atom of Au(I) in the zigzag chains. In the pathway of R4 involving Au-Au bonding in its initial structures (n ≤ 3), the distance between intermediate gold atoms grows with cluster size, ultimately resulting in the transfer of the intermediate Au-Au bonding into aurophilic interaction. The size effect on the structure and aurophilic interactions of these clusters will be better understood based on these discoveries, potentially providing new insights into the active but elusive chemical species involved in the corresponding catalytic reactions or nanoparticle synthesis processes.

Impact- and Thermal-Resistant Epoxy Resin Toughened with Acacia Honey.

High performance polymers with bio-based modifiers are promising materials in terms of applications and environmental impact. In this work, raw acacia honey was used as a bio-modifier for epoxy resin, as a rich source of functional groups. The addition of honey resulted in the formation of highly stable structures that were observed in scanning electron microscopy images as separate phases at the fracture surface, which were involved in the toughening of the resin. Structural changes were investigated, revealing the formation of a new aldehyde carbonyl group. Thermal analysis confirmed the formation of products that were stable up to 600 °C, with a glass transition temperature of 228 °C. An energy-controlled impact test was performed to compare the absorbed impact energy of bio-modified epoxy containing different amounts of honey with unmodified epoxy resin. The results showed that bio-modified epoxy resin with 3 wt% of acacia honey could withstand several impacts with full recovery, while unmodified epoxy resin broke at first impact. The absorbed energy at first impact was 2.5 times higher for bio-modified epoxy resin than it was for unmodified epoxy resin. In this manner, by using simple preparation and a raw material that is abundant in nature, a novel epoxy with high thermal and impact resistance was obtained, opening a path for further research in this field.

Anti-adhesive action of novel ruthenium(II) chlorophenyl terpyridine complexes with a high affinity for double-stranded DNA: in vitro and in silico.

Interactions of three Ru(II) chlorophenyl terpyridine complexes: [Ru(Cl-Ph-tpy)(en)Cl]Cl (1), [Ru(Cl-Ph-tpy)(dach)Cl]Cl (2) and [Ru(Cl-Ph-tpy)(bpy)Cl]Cl (3) (Cl-Ph-tpy = 4'-(4-chlorophenyl)-2,2':6',2''-terpyridine, en = 1,2-diaminoethane, dach = 1,2-diaminocyclohexane, bpy = 2,2'-bipyridine) with human serum albumin (HSA), calf thymus DNA and a double-helical oligonucleotide d(CGCGAATTCGCG)2 (1BNA) were examined. Fluorescence emission studies were used to assess the interactions of complexes with HSA, which were of moderate strength for 1 and 2. Molecular docking allowed us to predict mostly π-π stacking and van der Waals interactions between the complexes and the protein. We suggest that the complexes bind to a novel site on HSA, which is different from its druggable sites I, II or III. We suggest a partial intercalation of complexes through the minor groove as a possible mode of interaction with double-helical DNA. Finally, when applied to normal extravillous cell line HTR8/SVneo and JAr choriocarcinoma cell line, complexes 1 and 2 exerted anti-adhesive properties at very low doses, whereas complex 3 had a negligible effect. The obtained results are completion of our studies of Ru(II) terpyridyl complexes that carry N-N ancillary ligands. We suggest a new research direction towards studying the cellular effects of Ru(II) polypyridyl compounds.

Structure and stability of small lithium-chloride LinClm(0,1+) (n ≥ m, n = 1-6, m = 1-3) clusters.

In the present study, we report the results of a detailed theoretical investigation along with the experimental observations of chlorine-doped small lithium clusters. The cluster ions of the type LinClm+ (n ≥ m, n = 1-6, m = 1-3) were obtained by the evaporation of LiCl from a Knudsen cell as a chemical reactor in the temperature range between 1800 and 2700 K. Heterogeneous clusters with more than one Cl atom are produced and detected for the first time, and the experimental conditions for formation and stability are examined. The structural characteristics and stabilities of neutral and positively charged LinClm species are analyzed by using quantum chemistry methods. Doping lithium clusters with chlorine increases their stability, although there is a typical closed-shell-open-shell alternation in stability. Calculated dissociation energies are the best indicator of cluster stability of experimentally detected clusters. Heterogeneous lithium-chloride clusters can be viewed as species consisting of m negative Cl- ions and a positively charged Lin(1+,2+) "cage"; upon ionization, an electron departs from the lithium cage. An important reason for the higher stability of closed-shell clusters is the delocalization of electrons over the lithium cage, which is more energetically favored than localization of electrons between two lithium atoms. According to their ionization energies, the titled clusters can be classified as "superalkalis".

Ionization energies of LinX (n = 2, 3; X = Cl, Br, I) molecules.

Molecules of Li(n)X (n = 2, 3; X = Cl, Br, I) were examined with a magnetic sector mass spectrometer by surface ionization using a triple rhenium filament impregnated with fullerene (C60). The ionization energies obtained for Li(2)Cl, Li(2)Br and Li(2)I molecules are 3.8 +/- 0.1, 3.9 +/- 0.1 and 4.0 +/- 0.1 eV, respectively. The first ionization energy of Li(2)Cl is documented, while there are no literature data for the ionization energies of Li(2)Br and Li(2)I. The molecules of Li(3)Cl, Li(3)Br and Li(3)I were detected experimentally for the first time with ionization energies of 4.0 +/- 0.1, 4.1 +/- 0.1 and 4.1 +/- 0.1 eV, respectively. The ionization energies of Li(n)X (n = 2, 3; X = Cl, Br, I) are in correlation with the theoretical prediction of their hyperlithiated configurations.

Ionization energies of hypervalent Li2F, Li2Cl and Na2Cl molecules obtained by surface ionization electron impact neutralization mass spectrometry.

Ionization energies of hypervalent Li(2)F, Li(2)Cl and Na(2)Cl molecules detected by surface ionization electron impact neutralization mass spectrometry are reported. The ionization energies were 3.78 +/- 0.2 eV for Li(2)F, 4.93 +/- 0.2 eV for Li(2)Cl, and 4.21 +/- 0.2 eV for Na(2)Cl. The ionization energies (IE) agree with theoretical ionization energies calculated by ab initio methods, supporting the theoretical prediction that Li(2)F has a hyperlithiated configuration in which the odd electron delocalizes over the two lithiums and with photoionization measurement. The first ionization energy of Na(2)Cl was experimentally confirmed earlier and for Li(2)Cl as well.8 We have developed and used this new approach for the problem--in the present work ions were first formed by surface ionization, followed by electron attachment (neutralization).