Alignment of <i>phsA</i> sequences in 21 <i>S</i>. Choleraesuis.

<p>The deletion of G at position 760 resulted in a frame-shift mutation. The first sequence is H₂S-positive <i>S</i>. Choleraesuis strain SC-B67 (NC_006905.1).</p

Phylogenetic relationships of all <i>S</i>. Choleraesuis STs from MLST database by eBURST analysis.

<p>All <i>S</i>. Choleraesuis STs were divide into three clonal complexes. The blue solid circle represents the founder clonal complex. The red lines indicate SLVs between STs.</p

Electrochemical DNA Biosensor Based on a Tetrahedral Nanostructure Probe for the Detection of Avian Influenza A (H7N9) Virus

A DNA tetrahedral nanostructure-based electrochemical biosensor was developed to detect avian influenza A (H7N9) virus through recognizing a fragment of the hemagglutinin gene sequence. The DNA tetrahedral probe was immobilized onto a gold electrode surface based on self-assembly between three thiolated nucleotide sequences and a longer nucleotide sequence containing complementary DNA to hybridize with the target single-stranded (ss)­DNA. The captured target sequence was hybridized with a biotinylated-ssDNA oligonucleotide as a detection probe, and then avidin-horseradish peroxidase was introduced to produce an amperometric signal through the interaction with 3,3′,5,5′-tetramethylbenzidine substrate. The target ssDNA was obtained by asymmetric polymerase chain reaction (PCR) of the cDNA template, reversely transcribed from the viral lysate of influenza A (H7N9) virus in throat swabs. The results showed that this electrochemical biosensor could specifically recognize the target DNA fragment of influenza A (H7N9) virus from other types of influenza viruses, such as influenza A (H1N1) and (H3N2) viruses, and even from single-base mismatches of oligonucleotides. Its detection limit could reach a magnitude of 100 fM for target nucleotide sequences. Moreover, the cycle number of the asymmetric PCR could be reduced below three with the electrochemical biosensor still distinguishing the target sequence from the negative control. To the best of our knowledge, this is the first report of the detection of target DNA from clinical samples using a tetrahedral DNA probe functionalized electrochemical biosensor. It displays that the DNA tetrahedra has a great potential application as a probe of the electrochemical biosensor to detect avian influenza A (H7N9) virus and other pathogens at the gene level, which will potentially aid the prevention and control of the disease caused by such pathogens

Antimicrobial Resistance and Molecular Investigation of H₂S-Negative <i>Salmonella enterica</i> subsp. <i>enterica</i> serovar Choleraesuis Isolates in China

<div><p><i>Salmonella enterica</i> subsp. <i>enterica</i> serovar Choleraesuis is a highly invasive pathogen of swine that frequently causes serious outbreaks, in particular in Asia, and can also cause severe invasive disease in humans. In this study, 21 <i>S</i>. Choleraesuis isolates, detected from 21 patients with diarrhea in China between 2010 and 2011, were found to include 19 H₂S-negative <i>S</i>. Choleraesuis isolates and two H₂S-positive isolates. This is the first report of H₂S-negative <i>S</i>. Choleraesuis isolated from humans. The majority of H₂S-negative isolates exhibited high resistance to ampicillin, chloramphenicol, gentamicin, tetracycline, ticarcillin, and trimethoprim-sulfamethoxazole, but only six isolates were resistant to norfloxacin. In contrast, all of the isolates were sensitive to cephalosporins. Fifteen isolates were found to be multidrug resistant. In norfloxacin-resistant isolates, we detected mutations in the <i>gyrA</i> and <i>parC</i> genes and identified two new mutations in the <i>parC</i> gene. Pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and clustered regularly interspaced short palindromic repeat (CRISPR) analysis were employed to investigate the genetic relatedness of H₂S-negative and H₂S-positive <i>S</i>. Choleraesuis isolates. PFGE revealed two groups, with all 19 H₂S-negative <i>S</i>. Choleraesuis isolates belonging to Group I and H₂S-positive isolates belonging to Group II. By MLST analysis, the H₂S-negative isolates were all found to belong to ST68 and H₂S-positive isolates belong to ST145. By CRISPR analysis, no significant differences in CRISPR 1 were detected; however, one H₂S-negative isolate was found to contain three new spacers in CRISPR 2. All 19 H₂S-negative isolates also possessed a frame-shift mutation at position 760 of <i>phsA</i> gene compared with H₂S-positive isolates, which may be responsible for the H₂S-negative phenotype. Moreover, the 19 H₂S-negative isolates have similar PFGE patterns and same mutation site in the <i>phs</i>A gene, these results indicated that these H₂S-negative isolates may have been prevalent in China. These findings suggested that surveillance should be increased of H₂S-negative <i>S</i>. Choleraesuis in China.</p></div

CRISPR spacer content of the 21 <i>S</i>. Choleraesuis isolates.

<p>^#Novel spacer identified in this study.</p><p>CRISPR spacer content of the 21 <i>S</i>. Choleraesuis isolates.</p

Mutations detected in the <i>gyrA</i> and <i>parC</i> gene of H₂S-negative <i>S</i>. Choleraesuis isolates.

<p>Ser, serine. Gly, glycine. Ala, alanine. Tyr, tyrosine. Cys, cysteine. Arg, arginine. Pro, proline.</p><p>Mutations detected in the <i>gyrA</i> and <i>parC</i> gene of H₂S-negative <i>S</i>. Choleraesuis isolates.</p

Dendrogram analysis of PFGE for the 21 <i>S</i>. Choleraesuis isolates by <i>Xba</i>I-digestion.

<p>The strain number, species, origin and ST are shown for each isolate.</p

Managing Life Span of High-Energy LiNi_0.88Co_0.11Al_0.01O₂|C–Si Li-Ion Batteries

The life span of high-energy cells (3.5 Ah, 18 650, LiNi0.88Co0.11Al0.01O2 (NCA)|C/Si, cell type A) is investigated as a function of depth of discharges (DoD, between 20 and 100%) and cycling rates (between 1C and C/5). The most relevant degradation mechanism for this cell type is the cycling-induced fracturing of active material. This mechanical degradation of the anode is particularly damaging for the cell life span because it generates chain reactions, i.e., solid electrolyte interphase (SEI) formation. The impedance analysis indicates that electrolyte shortage occurs at the end of life (when the capacity loss exceeds 20%) of all cells, regardless of their cycling protocols. It is revealed that electrochemical activation of the Li0.75Si phase at around 3.0 V causes enormous mechanical stress. Therefore, all of the cells discharged down to 2.65 V show poor lifetime, regardless of their cycling rates and DoDs. The lifetime could be significantly prolonged by cycling the cells above 3.1 V. The scanning electron microscopy (SEM)–energy-dispersive spectrometry (EDX) reveals that some graphite particles are coated by the dense agglomeration of Si particles. The large volume changes of Si might also induce mechanical stress onto the topmost layer of graphite particles underneath the Si coatings, in addition to the mechanical degradation of the Si particle itself