The photochemical and thermal cis-to-trans isomerization of aromatic azo groups covalently bonded within polymers and its practical consequences as well as some other recent applications are reviewed. The kinetics and mechanism of the isomerization of azo polymers are briefly presented, and then several recent developments in azo polymers research are discussed. They include liquid crystallinity, nonlinear optical properties, monolayer assemblies, and the lightinduced birefringence and dichroism. Some of the phase transitions of liquid-crystalline azo polymers can be induced photochemically by the azo groups isomerization. Second-order optical nonlinearity can be obtained in polymers with donorand acceptor-substituted azo groups. Using the Langmuir-Blodgett technique, azo polymer monolayers can be built and used as "command surfaces" of liquid-crystal films. The light-induced birefringence is a reorientation phenomenon which is a consequence of the trans-cis-trans isomerization. Future possible applications for a variety of practical devices, such as display devices, optical modulators, optical waveguides, holography, and reversible optical storage are mentioned.

DNA N-methyladenine (6mA) modification is the most prevalent DNA modification in prokaryotes, but whether it exists in human cells and whether it plays a role in human diseases remain enigmatic. Here, we showed that 6mA is extensively present in the human genome, and we cataloged 881,240 6mA sites accounting for ∼0.051% of the total adenines. [G/C]AGG[C/T] was the most significantly associated motif with 6mA modification. 6mA sites were enriched in the coding regions and mark actively transcribed genes in human cells. DNA 6mA and N-demethyladenine modification in the human genome were mediated by methyltransferase N6AMT1 and demethylase ALKBH1, respectively. The abundance of 6mA was significantly lower in cancers, accompanied by decreased N6AMT1 and increased ALKBH1 levels, and downregulation of 6mA modification levels promoted tumorigenesis. Collectively, our results demonstrate that DNA 6mA modification is extensively present in human cells and the decrease of genomic DNA 6mA promotes human tumorigenesis.

ethyl]ethylamino]-4-nitroazobenzene] (pDRIA) is used as an example to demonstrate the ability of amorphous high-Tg azoaromatic-containing polymers to reversibly store optical information. Writing, reading, erasing, and rewriting processes are performed using laser beams on a pDRIA film. This ability is based on the well-known trans-cis-trans isomerization process which was previously studied on liquid-crystalline polymers containing azoaromatic groups. Liquid crystallinity is not a necessary condition for optical storage. As well, erasing can be performed optically, eliminating the need to heat the polymer sample. The writing and erasing are statistical processes, and the level of optical anisotropy induced depends on the photon flux directed at the sample. The time evolution of the writing process is investigated. A computer simulation of these processes is performed taking into account a relaxation process in which some of the reoriented trans molecules are randomized by thermal motion. The computer model replicates the general features of the optical storage processes. Possible applications and future work on this class of polymers are also discussed.

We present a tool that combines fast mapping, error correction, and de novo assembly (MECAT; accessible at https://github.com/xiaochuanle/MECAT) for processing single-molecule sequencing (SMS) reads. MECAT's computing efficiency is superior to that of current tools, while the results MECAT produces are comparable or improved. MECAT enables reference mapping or de novo assembly of large genomes using SMS reads on a single computer.

SummaryIn human cells, DNA 5-methylcytosine (5mC) modification plays an important role as an epigenetic mark. However, DNA N6-methyladenine modification (6mA), which is predominantly present in prokaryotes and a limited number of eukaryotes, is considered to be absent in human genomic DNA. Here, we show that 6mA is present in human genome, and we identified 881,240 6mA sites whose density is about 0.051% of the total adenines in the human genome DNA, but more than 0.18% in the mitochondrion genome. [G/C]AGG[C/T] was the most significant motif associated with 6mA modification. 6mA sites are enriched in the exon coding regions (P=0.02) and associated with transcriptional activation (P<0.001). We further identify that DNA N6-methyladenine and N6-demethyladenine modification is mediated by 6mA methytransferase N6AMT1 and 6mA demethytransferase ALKBH1, respectively. The 6mA abundance is significantly lower in cancer tissues compared to adjacent normal tissues, always accompanying with lower N6AMT1 and higher ALKBH1 level.Collectively, we uncover a DNA modification in human and describe a potential role of the N6AMT1/ALKBH1-6mA regulatory axis in the progression of human disease, such as cancer.not peer-reviewed)

Dichroism and birefringence are shown to be optically induced and erased in high-glass-transition azoaromatic polymers. The resulting polarization information is easily detected and exhibits long-term stability. This optically induced reorientation of the azoaromatic molecules will have wide applications in image recording and in electro-optical devices.

We report electroluminescence degradation studies of tris (8-hydroxyquinoline) aluminum (Alq3) organic light-emitting devices (OLEDs) under ambient conditions. Alq3 films and organic bilayer anode/naphthyl-substituted benzidine derivative/Alq3/cathode devices are studied via electroluminescence, photoluminescence, polarization microscopy and atomic force microscopy, and via microscopic infrared spectroscopy. Results reveal that humidity induces the formation of crystalline Alq3 structures in originally amorphous films. The same phenomenon is found to occur in OLEDs and causes cathode delamination at the Alq3/cathode interface that results in the formation of black (nonemissive) spots in the devices.

Long nanopore reads are advantageous in de novo genome assembly. However, nanopore reads usually have broad error distribution and high-error-rate subsequences. Existing error correction tools cannot correct nanopore reads efficiently and effectively. Most methods trim high-error-rate subsequences during error correction, which reduces both the length of the reads and contiguity of the final assembly. Here, we develop an error correction, and de novo assembly tool designed to overcome complex errors in nanopore reads. We propose an adaptive read selection and two-step progressive method to quickly correct nanopore reads to high accuracy. We introduce a two-stage assembler to utilize the full length of nanopore reads. Our tool achieves superior performance in both error correction and de novo assembling nanopore reads. It requires only 8122 hours to assemble a 35X coverage human genome and achieves a 2.47-fold improvement in NG50. Furthermore, our assembly of the human WERI cell line shows an NG50 of 22 Mbp. The high-quality assembly of nanopore reads can significantly reduce false positives in structure variation detection.