Difference analysis of regional population ageing from temporal and spatial perspectives: a case study in China

The ageing coefficient is selected as the index to evaluate population ageing, and some methods are proposed for analyzing differences in regional population ageing from temporal and spatial perspectives. China is used as the case study over the period 1998–2014. The concentration degree of the elderly varies regionally, but fluctuations in regional population ageing remain relatively stable. The coefficient of variation of population ageing fluctuates with an overall decreasing tendency. Population ageing in China exhibits a ladder-like distribution different from the distribution corresponding to economic strength. Spatial autocorrelation in population ageing is observed, with a comparatively steady spatial pattern.</p

Reaction of sodium bisulfite with C, 5-mC and 5-hmC.

<p>(A) Bisulfite-mediated deamination of cytosine. HSO₃⁻ reversibly and quickly adds across the 5,6 double bond of cytosine, promoting deamination at position 4 and conversion to 6-sulfonyluracil. 6-sulfonyluracil is stable under neutral conditions, but is easily desulfonated to uracil (U) at higher pH. (B) 5-methylcytosine is deaminated to thymine by bisulfite conversion, but the rate is approximately two orders of magnitude slower than that of cytosine. (C) Bisulfite quickly converts 5-hydroxymethylcytosine to form cytosine-5-methylenesulfonate (CMS). This adduct does not readily undergo deamination <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0008888#pone.0008888-Hayatsu2" target="_blank">[45]</a>.</p

5-hmC did not undergo C->T transitions after bisulfite treatment and 5-mC antibody cannot recognize 5-hmC in DNA.

<p>(A) Shown are sequencing traces of 5-hmC-containing oligonucleotide (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0008888#pone-0008888-g002" target="_blank"><b>Figure 2A</b></a>) before and after bisulfite treatment (<i>top and middle panels</i>). The control C-containing oligonucleotide shows complete conversion of all C's in the top strand (highlighted sequences) to T's (<i>lower panel</i>). (B) Dot-blot assay of monoclonal anti-5-mC antibody detection of oligonucleotide (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0008888#pone-0008888-g002" target="_blank"><b>Figure 2A</b></a>) containing 5-mC or 5-hmC (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0008888#pone-0008888-g002" target="_blank"><b>Figure 2A</b></a>). Recognition on DNA by the anti-5-mC antibody is shown in the top panel, loading control is shown by the methylene blue stain in the bottom panel. The anti-5-mC antibody only recognizes the 5-mC oligonucleotide but not the 5-hmC oligonucleotide.</p

LC-MS analysis of conversion efficiency of 5-hmC to CMS.

<p>(A) MS analysis of the nuclease P1 digestion products of the oligonucleotides used in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0008888#pone-0008888-g002" target="_blank"><b>Figure 2A</b></a>, before (upper panel) and after (lower panel) bisulfite treatment. (B) To determine the conversion efficiency of 5-hmC to CMS in the oligonucleotide shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0008888#pone-0008888-g002" target="_blank"><b>Figure 2A</b></a>, a standard curve was used to determine the unknown quantity of hmdCMP in the sample before and after treatment with sodium bisulfite (see text for details). The absolute value of the intercept of the best-fit line with the X-axis gives the concentration of hmdCMP remaining in the sample after bisulfite treatment as 4.69 nM. Given that the hmdCMP concentration before bisulfite treatment was 1.5 µM, this corresponds to a conversion efficiency as high as 99.7%.</p

Theoretical simulation of ion transport in main-chain poly(arylene piperidinium) anion exchange membranes with crown ether groups

Experimental studies have confirmed that introduction of the proper content of dibenzo-18-crown-6-ether (DE) into main-chain poly(arylene piperidinium) anion exchange membranes (AEMs) improved the efficiency of OH− transport. In this study, models of the AEMs (PDTP-x) were constructed with varying molar contents of DE groups (x = 0, 0.05, 0.10, 0.15, 0.20 and 0.25). Molecular dynamics simulations were employed to investigate the microscopic effects of the DE groups on OH− transport. The analysis examined the impact of the volume of the overlapping hydration shells around piperidinium groups and the continuities and uniformities of the ion transport channels. Furthermore, the stabilities of the hydrogen bonds between water molecules explained the effect of x on OH− transport. The results showed that the total overlap volume initially increased and then decreased as x increased. When the content of DE groups was appropriate, the hydration shells of the cations exhibited considerable overlap, which facilitated the formation of continuous and uniform ion transport channels. Additionally, the stabilities of the water hydrogen bonds initially decreased and then increased as x increased. The stabilities of the hydrogen bonds were lowest when the DE content was optimal, which facilitated the transport of OH−.</p

The bisulfite adduct of 5-hmC stalls Taq polymerase at CpG dinucleotides.

<p>(A) Sequences of a set of five 158 bp oligonucleotides used in this assay. At the position marked XXXX (red font with yellow highlight), the CG oligonucleotide contains the sequence CGAT, the CGCG oligonucleotide contains two tandem CGs, and the CC and CCGG oligonucleotides contain CCAT and CCGG sequences respectively. The underlined sequences correspond to the forward and reverse PCR primers used for PCR amplification. (B) Primer extension assays of oligonucleotides shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0008888#pone-0008888-g005" target="_blank"><b>Figure 5A</b></a>. The bands corresponding to stalled PCR reactions (red asterisks, see XXXX in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0008888#pone-0008888-g005" target="_blank"><b>Figure 5A</b></a>) were most prominent in 5-hmC-containing CC and CCGG oligonucleotides after bisulfite treatment, and were observed, though less obvious, in the CG and CGCG oligonucleotides. Full length product is indicated by an arrow. <i>Right lanes</i>, the Sanger sequencing was performed using the CCGG oligonucleotide as a template. (C) Quantification of Ct value of real-time PCR from experiments performed on the substrates used in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0008888#pone-0008888-g005" target="_blank"><b>Figure 5A</b></a>. The mean and standard deviation of three experiments is shown.</p

The bisulfite adduct of 5-hmC hinders PCR amplification.

<p>(A) Sequence of oligonucleotide containing multiple cytosines (used in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0008888#pone-0008888-g002" target="_blank"><b>Figures 2B-D</b></a>). The yellow highlighted sequences and the red asterisks indicate the sequences and cytosine (putative CMS) residues at which DNA polymerases tended to stall when bisulfite-treated 5-hmC-containing DNA was used as template, whereas the grey highlighted sequences and black asterisks indicate the sequences and cytosine (putative CMS) residues that cause weak or no stalling by the DNA polymerases (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0008888#pone-0008888-g002" target="_blank"><b>Figure 2D</b></a>). Cytosines in the first 106 bases of the oligonucleotide are difficult to distinguish via Sanger sequencing and thus are not annotated with regard to stalling. The underlined sequences correspond to the forward and reverse PCR primers used for PCR amplification. (B) Real-time PCR amplification curve of an oligonucleotide containing C, 5-mC or 5-hmC before and after bisulfite treatment. The sequence of the oligonucleotide is shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0008888#pone-0008888-g002" target="_blank"><b>Figure 2A</b></a>. The small lag observed for the bisulfite-treated cytosine oligonucleotide is due in part to the fact that after conversion of cytosine to uracil, this oligonucleotide can only be amplified from one of the two strands. (C) Quantification of Ct value from experiments performed as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0008888#pone-0008888-g002" target="_blank"><b>Figure 2B</b></a>. The mean and standard deviation of three experiments is shown. (D) Primer extension assays for DNA containing different cytosine species, shown beside a Sanger sequencing ladder. Ladders of incomplete extension products were only observed in the 5-hmC-containing DNA after bisulfite treatment, at positions corresponding to G in the Sanger sequencing ladder (<i>left lanes</i>). Red asterisks: positions with the most significant stalling; black asterisks: positions with weak stalling or no stalling. The corresponding sequences are indicated on the left (please compare with <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0008888#pone-0008888-g002" target="_blank"><b>Figure 2A</b></a>). The extension reaction performed with bisulfite-treated 5-hmC-containing DNA yielded less full-length product (arrow).</p

Poly(biphenyl piperidinium) Anion Exchange Membranes for Alkaline Water Electrolyzers: The Effect of Nonionic Pendant Groups

The introduction of different nonionic pendant groups in the backbones of polymeric anion exchange membrane (AEM) materials not only induces microphase separated morphology but also greatly impacts the other physicochemical properties of AEMs. Herein, we reported a series of poly­(biphenyl piperidinium) copolymers having different nonionic pendant groups on the backbones, including methyl, phenyl, and bromomethyl, which were derived from the ketone comonomers in the superacid-catalyzed polycondensation. Under similar ion exchange capacity, the PBP-M-35 membrane with methyl pendant groups shows the highest water uptake due to the less steric effect and electronic effect, reaching the highest OH– hydroxide conductivity (50.7 mS/cm at 20 °C in liquid water) than other membranes. In addition to high conductivity, the PBP-M-35 membrane with more water absorption displayed superior alkaline stability, with the retention of a conductivity of 84.5% after 1200 h in 1 M KOH at 80 °C. Consequently, the PBP-M-35 membrane presented a performance of 2000 mA/cm2 at 1.8 V in a water electrolyzer (with the IrO2 anode and Pt/C cathode in 1 M KOH at 80 °C). Further continuous operation under different conditions suggested that the cell with the PBP-B-30 membrane could operate under Ni-foam electrodes in 1 M KOH at 80 °C for 240 h, and more harsh working conditions (6 M KOH at 80 °C) led to the fast failure of the cell

Table_1_Prenatal Diagnosis of Microdeletions or Microduplications in the Proximal, Central, and Distal Regions of Chromosome 22q11.2: Ultrasound Findings and Pregnancy Outcome.docx

Several recurrent microdeletions and microduplications in the proximal, central, and distal regions of chromosomal 22q11.2 have been identified. However, due to a limited number of patients reported in the literature, highly variable clinical phenotypes, and incomplete penetrance, the pathogenicity of some microdeletions/microduplications in 22q11.2 central and distal regions is unclear. Hence, the genetic counseling and subsequent pregnancy decision are extremely challenging, especially when they are found in structurally normal fetuses. Here, we reported 27 consecutive cases diagnosed prenatally with 22q11.2 microdeletions or microduplications by chromosomal microarray analysis in our center. The prenatal ultrasound features, inheritance of the microdeletions/microduplications, and their effects on the pregnancy outcome were studied. We found that fetuses with 22q11.2 microdeletions were more likely to present with structure defects in the ultrasound, as compared with fetuses with 22q11.2 microduplications. Both the prenatal ultrasound findings and the inheritance of the microdeletions/microduplications affected the parent’s decision of pregnancy. Those with structure defects in prenatal ultrasound or occurred de novo often resulted in termination of the pregnancy, whereas those with normal ultrasound and inherited from healthy parent were likely to continue the pregnancy and led to normal birth. Our study emphasized that proximal, central, and distal 22q11.2 deletions or duplications were different from each other, although some common features were shared among them. More studies are warranted to demonstrate the underlying mechanisms of different clinical features of these recurrent copy-number variations, thereby to provide more information for genetic counseling of 22q11.2 microdeletions and microduplications when they are detected prenatally.</p

Improving the Properties of Anion Exchange Blend Membranes via Optimizing the NPBI Content and Deprotonation Degree: A Theoretical Study

Blending poly­[2,2′-(1,4-naphthalene)-5,5′-benzimidazole] (NPBI) with main chain-type N-spirocyclic quaternary ammonium ionenes (SI) could effectively improve the dimensional stability of anion exchange blend membranes (AEBMs), while the mechanism of the effect on OH– transport has not been elucidated. In this work, the effect of the NPBI content and deprotonation degree on OH– transport was revealed by molecular dynamics simulation. The simulation results showed that the free water content increased with increasing NPBI content at the same NPBI deprotonation degree, which facilitated the OH– transport. However, the decreased distance between adjacent N-spirocyclic quaternary ammonium cations (NSQAs) in the interchain and the increased correlation between OH– were detrimental to OH– transport. These resulted in AEBMs with 20 wt % NPBI content exhibiting the best OH– transport. When the NPBI content was 20 wt %, the distance between adjacent NSQAs in the interchain increased and OH– was more dispersed in the aqueous phase with decreasing NPBI deprotonation degrees, leading to the increased OH– transport. Because of the “trade-off” effect between the OH– transport and dimensional stability of AEBMs, we suggest that AEBMs with 20 wt % NPBI content and 50% NPBI deprotonation degree (SI/NP-50-20) can be selected to balance OH– transport and dimensional stability. This work will provide further guidance for the design of blend modification of AEBMs