DISTINÏCT: Data poISoning atTacks dectectIon usiNg optÏmized jaCcarddisTance

Machine Learning (ML) systems often involve a re-training process to make better predictions and classifications. This re-training process creates a loophole and poses a security threat for ML systems. Adversaries leverage this loophole and design data poisoning attacks against ML systems. Data poisoning attacks are a type of attack in which an adversary manipulates the training dataset to degrade the ML system’s performance. Data poisoning attacks are challenging to detect, and even more difficult to respond to, particularly in the Internet of Things (IoT) environment. To address this problem, we proposed DISTINÏCT, the first proactive data poisoning attack detection framework using distance measures. We found that Jaccard Distance (JD) can be used in the DISTINÏCT (among other distance measures) and we finally improved the JD to attain an Optimized JD (OJD) with lower time and space complexity. Our security analysis shows that the DISTINÏCT is secure against data poisoning attacks by considering key features of adversarial attacks. We conclude that the proposed OJD-based DISTINÏCT is effective and efficient against data poisoning attacks where in-time detection is critical for IoT applications with large volumes of streaming data.     

New insight into the interaction of sulfur with diesel NOx storage catalysts

A commercial NO_x-storage catalyst (NSC) has been subjected to different aging procedures on the engine bench simulating 100,000 km mileage. The aging consisted of cyclical sulfur exposure, subsequent sulfur removal and testing of the catalytic activity. More aggressive desulfation procedures result in more efficient sulfur removal and consequently good high temperature NO_x-conversion. However, low temperature NO_x-performance is lower than for agings employing more moderate desulfation conditions.

Sulfur post mortem analyses reveal a slight decrease of residual sulfur concentration over the length of all catalysts after completion of the aging. BET and CO-chemisorption data are in line with the increase of temperature from catalyst inlet to outlet during the desulfation. The conversion of BaCO₃ to BaSO₄ during the sulfur poisoning was followed by IR, TPD and TPR. A quantitative analysis of the data shows that at the end of the agings all residual sulfur is mainly located at barium sites as opposed to other oxide components like e.g. alumina or ceria. TPR data suggest that prolonged rich purges of the sulfated catalyst lead to an efficient decomposition of sulfates however some sulfur is being trapped in the form of BaS which seems difficult to remove under constant rich conditions.

XPS data suggest that the bulk sulfur amounts in the catalyst may be decoupled from the actual concentration at the catalyst surface. In that sense, the residual sulfur concentration might be limited in some cases as a criterion to assess the performance of a NSC. More reducing desulfation conditions cause the residual sulfur to be present in the form of more reduced sulfur species (sulfites, sulfides) on the catalyst.     

Fabrication of 2-dimensional platinum nanocatalyst arrays by electron beam lithography: ethylene hydrogenation and CO-poisoning reaction studies

Electron beam lithography (EBL) has been used to fabricate platinum nanoparticle arrays in the 20-nm size range on oxide thin films of silica and alumina deposited onto silicon wafers. A combination of characterization techniques (SEM, AFM, XPS, AES) has been used to determine size, spatial arrangement and cleanliness of these fabricated catalysts. Ethylene hydrogenation reaction studies have been carried out over these platinum nanoarrays and have revealed major differences in turnover rates and activation energies of the different nanostructures when clean and when poisoned with carbon monoxide. The oxide–metal interfaces are implicated as important reaction sites that remain active when the metal sites are poisoned by adsorbed carbon monoxide.     

TiAl基羰基硫水解催化剂的中毒机制与抗氧性能研究

高炉煤气脱硫是实现钢铁行业多工序全流程超低排放的关键。高炉煤气中主要有机硫组分是羰基硫（COS）,常用γ-Al₂O₃基催化剂水解脱除,但是其抗氧性能有待提高。采用共沉淀法制备了Ti_0.5Al和K_0.2Ti_0.5Al催化剂,考察了催化剂在含氧气氛下的COS水解催化性能,并分析了氧体积分数对COS转化率和H₂S产率的影响规律。活性测试结果表明,Ti_0.5Al催化剂的初始COS转化率接近90%,随着反应时间增长效率逐渐降低至60%以下;K_0.2Ti_0.5Al催化剂在0.5% （体积分数） O₂的气氛下持续反应22 h后,其COS转化率仍可保持在93.44%。表征结果显示,催化剂失活后比表面积大幅减小,表面碱性显著减弱。此外,活性中心Al原子硫酸化是导致催化剂失活的主要原因,而硫酸盐的沉积为次要原因。原位红外结果表明,K的引入可显著减弱O₂在催化剂表面的吸附,并且阻断中间过渡物种的氧化,这是K提高催化剂抗氧性能的关键。     

Screening children for elevated blood lead - learnings from the literature

INTRODUCTION: Although it is important that children at risk of developing elevated blood lead receive regular screening, attendance at screening programs is variable. A literature review was undertaken to better understand the factors that affect carers' decisions about whether or not to take their children for blood lead screening. METHOD: Electronic databases (Medline, EMBASE, CINAHL, Psychinfo) were searched to identify relevant publications, supported by reviewing reference lists of identified articles and searching with internet-based search engines. RESULTS: Thirty-four published studies dealing with blood lead screening rates were identified, of which only seven papers focused specifically on parent's attitudes to blood lead screening. The barriers to and enablers of screening for elevated blood lead levels appear to be similar to those identified for other screening programs. DISCUSSION: It is recommended that attendance at screening be routinely monitored, and that where participation is suboptimal further research be undertaken, in close co-operation with affected communities or sub-groups, to determine how best to encourage screening and to protect children from lead. It is important to minimize stigma and to ensure, as far as possible, that practical barriers such as lack of transport do not restrict access to screening programs.     

瓶装压缩气体的分类、危害及安全对策（下）

介绍了瓶装压缩气体的分类、危害及安全对策.     

干式煤气柜泄漏及中毒事故预测后果分析

文章通过对煤气柜煤气泄漏及扩散范围的研究,利用相应的数学模型可以估算出CO扩散影响的范围及相应的中毒人数,可以帮助企业了解煤气柜区域事故后果的影响范围,并对煤气柜这种重大危险源的管理和控制有一个量的概念。     

Optimization of a rapid QuEChERS sample treatment method for HILIC-MS2 analysis of paralytic shellfish poisoning (PSP) toxins in mussels

A rapid and simple QuEChERS sample treatment was proposed for the development of a selective hydrophilic interaction liquid chromatography-ESI-MS²-based method for the determination of saxitoxins (STXs) in mussel samples. Among different sorbents, ABS Elut-NEXUS phase, composed of polystyrene cross-linked with 50% divinyl benzene and poly(methyl methacrylate), provided the best results. The effects of experimental parameters, including sorbent amount, vortexing time and centrifugation time were investigated and optimized by experimental design. In particular, regression models and desirability functions were applied to find the experimental conditions providing the highest global extraction response. The method was validated under the optimized conditions; detection and quantification limits in the 3–159 μg/kg and 7–436 μg/kg ranges respectively were obtained, except for C2 for which highest values were calculated due to its low ESI ionization efficiency. Finally, the analysis of twenty-eight mussel samples permitted to detect and quantify some of the investigated STXs, proving the applicability of the devised method.     

Influence of ammonia on thiophene HDS at high pressures over noble metal catalysts for deep HDS applications

The thiophene hydrodesulfurization (HDS) activity of Pt/ASA, Pt/SiO₂, Ir/ASA and Ir/SiO₂ catalysts at thiophene concentrations of 300 ppm has been studied at 573 K and 20 bar. Pt/ASA showed the highest HDS activity. Nitrogen tolerance was investigated by co-feeding ammonia in gas phase concentrations from 10 to 1000 ppm. The amorphous silica alumina (ASA) supported catalysts were similarly strongly inhibited by the presence of ammonia, with even 10 ppm of ammonia causing a significant drop in activity, despite widely different dispersions. The SiO₂ supported catalysts were less severely affected by the presence of ammonia.     

稀土在催化裂化催化剂中的抗钒作用 Ⅰ.稀土对催化剂反应性能的影响

采用ＸＲＤ,ＳＥＭ,ＢＥＴ以及轻油微反、小型固定流化床反应等方法,研究了钒对ＳＲＹ分子筛的结构和裂化活性的影响,以及稀土氧化物对钒破坏作用的抑制。结果表明,沉积在催化剂上的稀土氧化物可以优先与钒反应,生成钒酸稀土,从而保护了催化剂中分子筛的结构;分子筛晶内的稀土离子,同样容易与钒反应,也生成钒酸稀土,从而加剧了钒对分子筛结构的破坏。氧化铈较氧化镧更容易与钒反应,因而具有更强的抗钒能力。