A semantic backdoor attack against Graph Convolutional Networks

Graph convolutional networks (GCNs) have been very effective in addressing the issue of various graph-structured related tasks, such as node classification and graph classification. However, recent research has shown that GCNs are vulnerable to a new type of threat called a backdoor attack, where the adversary can inject a hidden backdoor into GCNs so that the attacked model performs well on benign samples, but its prediction will be maliciously changed to the attacker-specified target label if the hidden backdoor is activated by the attacker-defined trigger. In this paper, we investigate whether such semantic backdoor attacks are possible for GCNs and propose a semantic backdoor attack against GCNs (SBAG) under the context of graph classification to reveal the existence of this security vulnerability in GCNs. SBAG uses a certain type of node in the samples as a backdoor trigger and injects a hidden backdoor into GCN models by poisoning training data. The backdoor will be activated, and the GCN models will give malicious classification results specified by the attacker even on unmodified samples as long as the samples contain enough trigger nodes. We evaluate SBAG on four graph datasets. The experimental results indicate that SBAG can achieve attack success rates of approximately 99.9% and over 82% for two kinds of attack samples, respectively, with poisoning rates of less than 5%

Synthesis of sphingosine analogues by diastereospecific amination of enantiopure trans-gamma, delta-unsaturated-beta-hydroxyesters

Sphingolipids play critical roles in signal transduction, intercellular membrane trafficking and cell growth. As bioactive sphingolipids, ceramide and sphingosine have been implicated in activating anti-proliferative and apoptotic responses in various cancer cells. Conversely, metabolic conversion of ceramide into sphingosine 1-phosphate, ceramide 1-phosphate and glucosylceramide regulates cell proliferation and suppresses ceramide programmed cell death. Many anticancer drugs and stress-induced agonists have been developed to increase endogenous ceramide levels. Sphingosine/ceramide analogues reportedly enhance antitumor activity and have been proposed as a potential new class of chemotherapeutic agents. Among these, sphingosines with aromatic substituents in the side chain often exhibit stronger biological activity compared to natural sphingosines. While a large number of synthetic pathways to sphingosine analogues have been described in the literature, very few pathways provide analogues with high stereospecificity. This dissertation describes a novel synthetic pathway to aromatic sphingosines which is highly stereospecific, provides good yields, uses commonly available reagents, and is versatile in terms of its potential to provide a large family of sphingosine analogues for future research. The entry into the synthetic pathway toward sphingosine analogues involves first the enantiospecific synthesis of trans-γ, δ-unsaturated β-hydroxyesters using biocatalytic reduction of trans-γ, δ-unsaturated-β-ketoesters with commercially available ketoreductases. With the advantages of compatibility with carbon-carbon double bonds, high enantioselectivity, broader substrate acceptance, mild environmentally-friendly reaction conditions and easy separation, the biocatalytic reduction was found to be superior compared to other more traditional chemical methods. Indeed, both (R) and (S)- enantiomers of trans-γ, δ-unsaturated β-hydroxyesters are synthesized by one or more ketoreductases in excellent stereochemical purity and high yield. The enantiopure trans-y, δ-unsaturated β-hydroxyesters were used to prepare erthyro-sphingosine analogues with aromatic substituents in the side chain. The strategy is based on the diastereospecific amination of trans-γ, δ-unsaturated β-hydroxyesters to introduce the amino group and establish anti N-Boc-α-hydrazine-β-liydroxyesters. Proper E1cB non-reductive elimination is essential for the successful cleavage of N-N bond of the hydrazine group. No racemization is detected during the entire course of the synthetic pathway. A total novel synthetic route of sphingosine analogues was thus accomplished with stereochemically pure intermediates and products

Accurate extrinsic calibration between monocular camera and sparse 3D Lidar points without markers

It is of practical interest to automatically calibrate the multiple sensors in autonomous vehicles. In this paper, we deal with an interesting case when used low-resolution Lidar and present a practical approach to extrinsic calibration between monocular camera and Lidar with sparse 3D measurements. We formulate the problem as directly minimizing the feature error evaluated between frames following the way of image warping. To overcome the difficulties in the optimization problem, we propose to use the distance transform and further projection error model to obtain the key approximated edge points that are sensitive to the loss function. Finally, the loss minimization is solved by an efficient random selection algorithm. Experimental results on KITTI dataset show that our proposed method can achieve competitive results and an improvement in translation estimation particularly.The work is support by National Nature Science Foundation of China under Grant No. 61375050, Grant No. 91220301 and Grant No. 61420106007, and funded in part by Australian Research Council Grants of DP120103896, LP100100588, DE140100180 ARC Centre of Excellence on Robotic Vision (CE140100016) and NICTA (Data61). The first author is funded by the Chinese Scholarship Council (CSC) to be a joint PhD student from NUDT to ANU

Emitter-Active Shell in NaYF₄:Yb,Er/NaYF₄:Er Upconversion Nanoparticles for Enhanced Energy Transfer in Photodynamic Therapy

To realize the potential of near-infrared (NIR) upconversion nanosensitizers for photodynamic therapy of cancer, upconversion luminescence and energy transfer (ET) efficiency from emitter donors to photosensitizer acceptors need to be improved. In the current work, upconversion nanoparticles (UCNPs) with a core/emitter-active shell structure were constructed to enhance not only the upconversion emission but also the ET from the nanoparticles to surface-anchored photosensitizers. The emitter was doped into the shell to bridge the migration of upconverted energy to the surface. NaYF4:Yb,Er/NaYF4:Er UCNPs and rose bengal (RB) photosensitizer were employed as an example. The upconversion emission was lifted by up to ∼81 times of the core counterpart. The bridge effect of the emitter-doped shell was obvious for the constructed nanophotosensitizer. The emission of the RB photosensitizer was up to ∼36 times that of the core counterpart. The NaYF4:Yb,Er/NaYF4:Er UCNPs also endow the RB photosensitizers with the most efficient reactive oxygen species production capability under NIR irradiation. In vitro photodynamic tests on glioma cells were conducted to validate the efficacy of the NaYF4:Yb,Er/NaYF4:Er/RB agent. Therefore, this work can facilitate the development of ET-based upconversion nanosystems

BPTF promotes tumor growth and predicts poor prognosis in lung adenocarcinomas.

BPTF, a subunit of NURF, is well known to be involved in the development of eukaryotic cell, but little is known about its roles in cancers, especially in non-small-cell lung cancer (NSCLC). Here we showed that BPTF was specifically overexpressed in NSCLC cell lines and lung adenocarcinoma tissues. Knockdown of BPTF by siRNA significantly inhibited cell proliferation, induced cell apoptosis and arrested cell cycle progress from G1 to S phase. We also found that BPTF knockdown downregulated the expression of the phosphorylated Erk1/2, PI3K and Akt proteins and induced the cleavage of caspase-8, caspase-7 and PARP proteins, thereby inhibiting the MAPK and PI3K/AKT signaling and activating apoptotic pathway. BPTF knockdown by siRNA also upregulated the cell cycle inhibitors such as p21 and p18 but inhibited the expression of cyclin D, phospho-Rb and phospho-cdc2 in lung cancer cells. Moreover, BPTF knockdown by its specific shRNA inhibited lung cancer growth in vivo in the xenografts of A549 cells accompanied by the suppression of VEGF, p-Erk and p-Akt expression. Immunohistochemical assay for tumor tissue microarrays of lung tumor tissues showed that BPTF overexpression predicted a poor prognosis in the patients with lung adenocarcinomas. Therefore, our data indicate that BPTF plays an essential role in cell growth and survival by targeting multiply signaling pathways in human lung cancers

Direct and Indirect Recycling Strategies of Expired Oxytetracycline for the Anode Material in Lithium Ion Batteries

It is well-known that the antibiotics inhibit the wide spread of various infection diseases and guarantee the life safety of many patients. However, various waste antibiotics into the environment also pose the great challenges of the environmental contamination and the ecological poison. Unreasonable disposal of expired antibiotics is one of the main sources of waste antibiotics in the ecological environment. For this reason, in order to focus on the circular economy of such highly refined medical grade chemicals, expired oxytetracycline was recycled for the anode active material in lithium ion batteries (LIBs) by direct and indirect strategies. That is, it was directly used as the anode active material or recycled by two-step carbonization for LIBs anode. Furthermore, the effect of these two strategies on the electrochemical performances was also discussed. Both anode materials showed their individual advantages and high feasibility for LIBs anode. For example, both them delivered the satisfactory Li-storage performances. Additionally, the direct route possessed lower recycling cost and high recovery rate, while the application range of carbon material in the indirect route was broader

A Versatile Approach for Siteâ Specific Lysine Acylation in Proteins

Using amber suppression in coordination with a mutant pyrrolysylâ tRNA synthetaseâ tRNAPyl pair, azidonorleucine is genetically encoded in E. coli. Its genetic incorporation followed by traceless Staudinger ligation with a phosphinothioester allows the convenient synthesis of a protein with a siteâ specifically installed lysine acylation. By simply changing the phosphinothioester identity, any lysine acylation type could be introduced. Using this approach, we demonstrated that both lysine acetylation and lysine succinylation can be installed selectively in ubiquitin and synthesized histone H3 with succinylation at its K4 position (H3K4su). Using an H3K4suâ H4 tetramer as a substrate, we further confirmed that Sirt5 is an active histone desuccinylase. Lysine succinylation is a recently identified postâ translational modification. The reported technique makes it possible to explicate regulatory functions of this modification in proteins.Azidonorleucine, an azideâ containing amino acid, is genetically encoded and incorporated into model proteins. This incorporation followed by traceless Staudinger ligation potentiates the synthesis of proteins with a myriad of siteâ specific lysine acylations.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137311/1/anie201611415-sup-0001-misc_information.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137311/2/anie201611415_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137311/3/anie201611415.pd

The Recovery of the Waste Cigarette Butts for N-Doped Carbon Anode in Lithium Ion Battery

As one of the common life garbages, about 4.5 trillion waste cigarette butts are produced and randomly discarded every year due to the addiction to the nicotine and the need of the social intercourse. Such a treatment would result in the waste of the resources and the environmental pollution if they weren't reasonably recycled in time. Herein, the waste cigarette butts were recycled in form of N-doped carbon powders with high economic value-added via one-step facile carbonization at 800°C for 2 h in the inert N2 atmosphere. The waste-cigarette-butts-derived black carbon powders were characterized by scanning electron microscope (SEM), N2 adsorption/desorption, and X-ray photoelectron spectroscopy (XPS). Furthermore, the corresponding electrochemical performances as the anode in lithium ion battery (LIB) were also investigated by galvanostatic charge/discharge, cyclic voltammetry (CV), and alternating current (AC) impedance. The results suggested that the recycled N-doped waste cigarette butts carbon (WCBC) powders consisted of major carbon and minor residual N-containing and O-containing functional groups, and the corresponding specific surface area was about 1,285 m2·g−1. Furthermore, the reversible specific discharge capacity was about 528 mAh·g−1 for 100 cycles at 25 mA·g−1 and about 151 mAh·g−1 even at 2,000 mA·g−1 for 2,500 cycles. Additionally, full cell performances were also satisfactory, indicating high feasibility. N-doping effect (such as additional active sites and higher electronic conductivity) and the residual O-containing functional groups may be responsible for the satisfactory electrochemical performances, which offered good inspiration and strategy to develop the green energy and circular economy