One-pot Synthesis of IPN Hydrogels with Enhanced Mechanical Strength for Synergistic Adsorption of Basic Dyes

<div><p>Interpenetrating polymer network (IPN) hydrogels based on chitosan (CS) and poly(acrylic acid) (PAA) were prepared by one-pot strategy. The hydrogels exhibited porous structure and enhanced mechanical strength due to the entrapment of the two polymeric networks in the IPN. The ability of the hydrogels to adsorb basic dye Nil Blue (BB 12) from aqueous solutions was assessed using UV-VIS spectrophotometer. The adsorption amount was pH dependent, and the maximum adsorption capacity was observed at pH 10.0. The adsorption equilibrium was achieved within 45 minutes and the adsorption process could be well described by the pseudo-second-order kinetic model and Langmuir isotherm. Furthermore, the synergistic interactions between dyes and the two polymeric networks in the IPN were found during the adsorption process. Thermodynamic parameters revealed the dye sorption was an endothermic and spontaneous process with increasing randomness at the hydrogel/solution interface. Finally, studies on the reproducibility suggested that the hydrogel could be repeatedly used without any significant loss of the adsorption capacity.</p></div

DFT Studies on the Mechanism of the Rhodium(III)-Catalyzed C–H Activation of <i>N</i>‑Phenoxyacetamide

A density functional theory (DFT) study has been conducted to elucidate the mechanism of the rhodium­(III)-catalyzed C–H activation of <i>N</i>-phenoxyacetamide, where the amido component of an internal oxidant serves as a leaving group. The impact of different substrates (alkynes versus cyclopropenes) on the reaction mechanism has been discussed in detail. The pathway for cyclopropene substrate proceeded via a Rh­(V) nitrene, while Rh­(III) remained unchanged throughout the pathway for alkyne substrate. The C–O bond-forming reductive elimination and O–N bond cleavage steps simultaneously occurred for the alkyne substrate. However, the C–O bond was formed by an electrocyclization from a Rh­(III) intermediate for the cyclopropene substrate. The energy profiles for the cyclopropene substrate were accompanied by a change in spin-state because the triplet spin state of a Rh­(V) nitrene complex is lower than that of the singlet spin state

Independent Expansion of Zincin Metalloproteinases in Onygenales Fungi May Be Associated with Their Pathogenicity

<div><p>To get a comprehensive view of fungal M35 family (deuterolysin) and M36 family (fungalysin) genes, we conducted genome-wide investigations and phylogenetic analyses of genes in these two families from 50 sequenced Ascomycota fungi with different life styles. Large variations in the number of M35 family and M36 family genes were found among different fungal genomes, indicating that these two gene families have been highly dynamic through fungal evolution. Moreover, we found obvious expansions of Meps in two families of Onygenales: Onygenaceae and Arthodermataceae, whereas species in family Ajellomycetace did not show expansion of these genes. The strikingly different gene duplication and loss patterns in Onygenales may be associated with the different pathogenicity of these species. Interestingly, likelihood ratio tests (LRT) of both M35 family and M36 family genes suggested that several branches leading to the duplicated genes in dermatophytic and <i>Coccidioides</i> fungi had signatures of positive selection, indicating that the duplicated <i>Mep</i> genes have likely diverged functionally to play important roles during the evolution of pathogenicity of dermatophytic and <i>Coccidioides</i> fungi. The potentially positively selected residues discovered by our analysis may have contributed to the development of new physiological functions of the duplicated <i>Mep</i> genes in dermatophytic fungi and <i>Coccidioides</i> species. Our study adds to the current knowledge of the evolution of Meps in fungi and also establishes a theoretical foundation for future experimental investigations.</p></div

Duplication and loss events of M35 family genes and M36 family genes in Onygenales fungi.

<p>The reconciliation between species tree and gene tree of Onygenales fungi along with the confirmation of the gene loss/duplication scenario were determined by using Notung 2.6 <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0090225#pone.0090225-Chen1" target="_blank">[21]</a>. The species tree of Onygenales fungi is shown as <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0090225#pone.0090225.s007" target="_blank">Fig. S7</a>. Putative duplication events are indicated with solid cycles, while loss events are indicated with thick branches. a, duplication and loss events of M35 family genes. b, duplication and loss events of M36 family genes.</p

Number of both M35 family and M36 family genes in different fungal species.

<p>Number of both M35 family and M36 family genes in different fungal species.</p

ML tree based on amino acid sequences of 105 M35 family genes.

<p>The tree was performed using PHYML 3.0<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0090225#pone.0090225-Guindon1" target="_blank">[17]</a>. The best-fitting model WAG+I+G and their parameters (I = 0.03, G = 1.912) which were estimated by program ProtTest <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0090225#pone.0090225-Galgiani1" target="_blank">[50]</a> were used in the ML analysis. The reliability of the tree topology was evaluated using bootstrap support <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0090225#pone.0090225-Felsenstein1" target="_blank">[20]</a> with 100.</p

Duplication and loss events of M35 family genes in Eurotiales fungi.

<p>The reconciliation between species tree and gene tree of Eurotiales fungi along with the confirmation of the gene loss/duplication scenario were determined by using Notung 2.6 <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0090225#pone.0090225-Chen1" target="_blank">[21]</a>. The species tree of Eurotiale fungi is shown as <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0090225#pone.0090225.s008" target="_blank">Fig. S8</a>. Putative duplication events are indicated with solid cycles, while loss events are indicated with thick branches. 1, the lineage includes species of <i>A. fumigatus, N. fischeri</i> and <i>A. clavatus</i>. 2, the lineage includes species of <i>A. nidulans</i>, <i>A. terreus, A. oryza</i> and <i>A. flavus</i>.</p

Phylogenetic tree of 38 M36 family genes used for codon-based maximum likelihood analysis in PAML.

<p>Phylogenetic trees were collapsed with inconsistent nodes from different tree-building methods and poor statistical supports into polytomy. Branches <i>a-j</i> indicated putative duplication events in Onygenales fungi. The branches with significant evidence of positive selection are indicated as a thick branch. The putative positively selected residues along these branches were shaded in grey.</p

CODEML analyses of selective pattern for M35 family genes.

a<p>In<i>L</i> is the log-likelihood scores.</p>b<p>LRT to detect adaptive evolution. *** P<0.001</p>c<p>Posterior probabilities value of each codon site were showed in parentheses.</p

Phylogenetic tree of 62 M35 family genes used for codon-based maximum likelihood analysis in PAML.

<p>Phylogenetic trees were collapsed with inconsistent nodes from different tree-building methods and poor statistical supports into polytomy. Branches <i>a-s</i> indicated putative duplication events in Onygenales fungi. The branches with significant evidence of positive selection are indicated as a thick branch. The putative positively selected residues along these branches were shaded in grey.</p