Suppressing Voltage Fading of Li‐Rich Oxide Cathode via Building a Well‐Protected and Partially‐Protonated Surface by Polyacrylic Acid Binder for Cycle‐Stable Li‐Ion Batteries

Li‐rich manganese based oxides (LRMOs) are considered an attractive high‐capacity cathode for advanced Li‐ion batteries; however, their poor cyclability and gradual voltage fading have hindered their practical applications. Herein, an efficient and facile strategy is proposed to stabilize the lattice structure of LRMOs by surface modification of polyacrylic acid (PAA). The PAA‐coated LRMO electrode exhibits only 104 mV of the voltage fading after 100 cycles and 88% capacity retention over 500 cycles. The structural stability is attributed to the carboxyl groups in PAA chains reacting with oxygen species on the surface of LRMO to form a uniform and tightly coated film, which significantly suppresses the dissolution of transition metal elements from the cathode materials into the electrolyte. Importantly, a H⁺/Li⁺ exchange reaction takes place between the LRMO and PAA, generating a proton‐doped surface layer. Density functional theory calculations and experimental evidence demonstrates that the H⁺ ions in the surface lattice efficiently inhibit the migration of transition metal ions, leading to a stabilized lattice structure. This surface modification approach may provide a new route to building a stable Li‐rich oxide cathode with high capacity retention and low voltage fading for practical Li‐ion battery applications.     

蛋白质序列的六维表示与相似性分析

给出了蛋白质序列的一种六维表示方法,根据这种表示方法有3种不同表示形式,利用这3种形式来构造距离矩阵的信息熵,然后通过信息熵向量的欧式距离、夹角来比较序列之间的相似性。     

Immunoglobulin G Expression in Lung Cancer and Its Effects on Metastasis

Lung cancer is one of the leading malignancies worldwide, but the regulatory mechanism of its growth and metastasis is still poorly understood. We investigated the possible expression of immunoglobulin G (IgG) genes in squamous cell carcinomas and adenocarcinomas of the lung and related cancer cell lines. Abundant mRNA of IgG and essential enzymes for IgG synthesis, recombination activation genes 1, 2 (RAG1, 2) and activation-induced cytidine deaminase (AID) were detected in the cancer cells but not in adjacent normal lung tissue or normal lung epithelial cell line. The extents of IgG expression in 86 lung cancers were found to associate with clinical stage, pathological grade and lymph node metastasis. We found that knockdown of IgG with siRNA resulted in decreases of cellular proliferation, migration and attachment for cultured lung cancer cells. Metastasis-associated gene 1 (MTA1) appeared to be co-expressed with IgG in lung cancer cells. Statistical analysis showed that the rate of IgG expression was significantly correlated to that of MTA1 and to lymph node metastases. Inhibition of MTA1 gene expression with siRNA also led to decreases of cellular migration and attachment for cultured lung cancer cells. These evidences suggested that inhibition of cancer migration and attachment induced by IgG down-regulation might be achieved through MTA1 regulatory pathway. Our findings suggest that lung cancer-produced IgG is likely to play an important role in cancer growth and metastasis with significant clinical implications.     

Construction of a SNP-based genetic linkage map in cultivated peanut based on large scale marker development using next-generation double-digest restriction-site-associated DNA sequencing (ddRADseq)

Background

Cultivated peanut, or groundnut (Arachis hypogaea L.), is an important oilseed crop with an allotetraploid genome (AABB, 2n = 4x = 40). In recent years, many efforts have been made to construct linkage maps in cultivated peanut, but almost all of these maps were constructed using low-throughput molecular markers, and most show a low density, directly influencing the value of their applications. With advances in next-generation sequencing (NGS) technology, the construction of high-density genetic maps has become more achievable in a cost-effective and rapid manner. The objective of this study was to establish a high-density single nucleotide polymorphism (SNP)-based genetic map for cultivated peanut by analyzing next-generation double-digest restriction-site-associated DNA sequencing (ddRADseq) reads.

Results

We constructed reduced representation libraries (RRLs) for two A. hypogaea lines and 166 of their recombinant inbred line (RIL) progenies using the ddRADseq technique. Approximately 175 gigabases of data containing 952,679,665 paired-end reads were obtained following Solexa sequencing. Mining this dataset, 53,257 SNPs were detected between the parents, of which 14,663 SNPs were also detected in the population, and 1,765 of the obtained polymorphic markers met the requirements for use in the construction of a genetic map. Among 50 randomly selected in silico SNPs, 47 were able to be successfully validated. One linkage map was constructed, which was comprised of 1,685 marker loci, including 1,621 SNPs and 64 simple sequence repeat (SSR) markers. The map displayed a distribution of the markers into 20 linkage groups (LGs A01–A10 and B01–B10), spanning a distance of 1,446.7 cM. The alignment of the LGs from this map was shown in comparison with a previously integrated consensus map from peanut.

Conclusions

This study showed that the ddRAD library combined with NGS allowed the rapid discovery of a large number of SNPs in the cultivated peanut. The first high density SNP-based linkage map for A. hypogaea was generated that can serve as a reference map for cultivated Arachis species and will be useful in genetic mapping. Our results contribute to the available molecular marker resources and to the assembly of a reference genome sequence for the peanut.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-351) contains supplementary material, which is available to authorized users.     

Roxithromycin treatment inhibits TGF-β1-induced activation of ERK and AKT and down-regulation of Caveolin-1 in rat airway smooth muscle cells

Background

Roxithromycin (RXM) has been widely used in asthma treatment; however, the mechanism has not been fully understood. The aim of our study was to investigate the underlying mechanism of RXM treatment in mediating the effect of transforming growth factor (TGF)-β1 on airway smooth muscle cells (ASMCs) proliferation and caveolinn-1 expression.

Methods

Firstly, the rat ovalbumin (OVA) model was built according to the previous papers. Rat ASMCs were prepared and cultured, and then TGF-β1 production in ASMCs was measured by enzyme-linked immunosorbent assay (ELISA). Moreover, the proliferation of ASMCs was determined using cell counting kit (CCK-8) assay. Additionally, the expressions of caveolin-1, phosphorylated-ERK1/2 (p-ERK1/2) and phosphorylated–AKT (p-AKT) in ASMCs treated with or without PD98059 (an ERK1/2 inhibitor), wortannin (a PI3K inhibitor), β-cyclodextrin (β-CD) and RXM were measured by Western blot. Finally, data were evaluated using t–test or one-way ANOVA, and then a P value < 0.05 was set as a threshold.

Results

Compared with normal control, TGF-β1 secretion was significantly increased in asthmatic ASMCs; meanwhile, TGF-β1 promoted ASMCs proliferation (P < 0.05). However, ASMCs proliferation was remarkably inhibited by RXM, β-CD, PD98059 and wortmannin (P < 0.05). Moreover, the expressions of p-ERK1/2 and p-AKT were increased and peaked at 20 min after TGF-β1 stimulation, and then suppressed by RXM. Further, caveolin-1 level was down-regulated by TGF-β1 and up-regulated by inhibitors and RXM.

Conclusion

Our findings demonstrate that RXM treatment inhibits TGF-β1-induced activation of ERK and AKT and down-regulation of caveolin-1, which may be the potential mechanism of RXM protection from chronic inflammatory diseases, including bronchial asthma.     

Synthesis and biological evaluation of 18F labeled fluoro-oligo-ethoxylated 4-benzylpiperazine derivatives for sigma-1 receptor imaging

We report the synthesis and evaluation of a series of fluoro-oligo-ethoxylated 4-benzylpiperazine derivatives as potential σ₁ receptor ligands. In vitro competition binding assays showed that 1-(1,3-benzodioxol-5-ylmethyl)-4-(4-(2-fluoroethoxy)benzyl)piperazine (6) exhibits low nanomolar affinity for σ₁ receptors (K_i = 1.85 ± 1.59 nM) and high subtype selectivity (σ₂ receptor: K_i = 291 ± 111 nM; K_iσ₂/K_iσ₁ = 157). [¹⁸F]6 was prepared in 30–50% isolated radiochemical yield, with radiochemical purity of >99% by HPLC analysis after purification, via nucleophilic ¹⁸F^? substitution of the corresponding tosylate precursor. The log D_{pH 7.4} value of [¹⁸F]6 was found to be 2.57 ± 0.10, which is within the range expected to give high brain uptake. Biodistribution studies in mice demonstrated relatively high concentration of radiotracers in organs known to contain σ₁ receptors, including the brain, lungs, kidneys, heart, and spleen. Administration of haloperidol 5 min prior to injection of [¹⁸F]6 significantly reduced the concentration of radiotracers in the above-mentioned organs. The accumulation of radiotracers in the bone was quite low suggesting that [¹⁸F]6 is relatively stable to in vivo defluorination. The ex vivo autoradiography in rat brain showed high accumulation of radiotracers in the brain areas known to possess high expression of σ₁ receptors. These findings suggest that [¹⁸F]6 is a suitable radiotracer for imaging σ₁ receptors with PET in vivo.