α-pinene photooxidation under controlled chemical conditions – Part 2: SOA yield and composition in low- and high-NO_x environments

The gas-phase oxidation of α-pinene produces a large amount of secondary organic aerosol (SOA) in the atmosphere. A number of carboxylic acids, organosulfates and nitrooxy organosulfates associated with α-pinene have been found in field samples and some are used as tracers of α-pinene oxidation. α-pinene reacts readily with OH and O_3 in the atmosphere followed by reactions with both HO_2 and NO. Due to the large number of potential reaction pathways, it can be difficult to determine what conditions lead to SOA. To better understand the SOA yield and chemical composition from low- and high-NO_x OH oxidation of α-pinene, studies were conducted in the Caltech atmospheric chamber under controlled chemical conditions. Experiments used low O_3 concentrations to ensure that OH was the main oxidant and low α-pinene concentrations such that the peroxy radical (RO_2) reacted primarily with either HO_2 under low-NO_x conditions or NO under high-NO_x conditions. SOA yield was suppressed under conditions of high-NO_x. SOA yield under high-NO_x conditions was greater when ammonium sulfate/sulfuric acid seed particles (highly acidic) were present prior to the onset of growth than when ammonium sulfate seed particles (mildly acidic) were present; this dependence was not observed under low-NO_x conditions. When aerosol seed particles were introduced after OH oxidation, allowing for later generation species to be exposed to fresh inorganic seed particles, a number of low-NO_x products partitioned to the highly acidic aerosol. This indicates that the effect of seed acidity and SOA yield might be under-estimated in traditional experiments where aerosol seed particles are introduced prior to oxidation. We also identify the presence of a number of carboxylic acids that are used as tracer compounds of α-pinene oxidation in the field as well as the formation of organosulfates and nitrooxy organosulfates. A number of the carboxylic acids were observed under all conditions, however, pinic and pinonic acid were only observed under low-NO_x conditions. Evidence is provided for particle-phase sulfate esterification of multi-functional alcohols

Synthesis of positively and negatively charged silver nanoparticles and their deposition on the surface of titanium

Bacterial infections related to dental implants are currently a significant complication. A good way to overcome this challenge is functionalization of implant surface with Ag nanoparticles (NPs) as antibacterial agent. This article aims at review the synthesis routes, size and electrical properties of AgNPs. Polyvinyl pyrrolidone (PVP) and polyethyleneimine (PEI) were used as stabilizers. Dynamic Light Scattering, Nanoparticle Tracking Analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDX) have been used to characterize the prepared AgNPs. Two types of NPs were synthesized in aqueous solutions: PVP-stabilized NPs with a diameter of the metallic core of 70 ± 20 nm, and negative charge of -20 mV, PEI-stabilized NPs with the size of the metallic core of 50 ± 20 nm and positive charge of +55 mV. According to SEM results, all the NPs have a spherical shape. Functionalization of the titanium substrate surface with PVP and PEI-stabilized AgNPs was carried out by dropping method. XRD patterns revealed that the AgNPs are crystalline with the crystallite size of 14 nm

Heavy metal accumulation by Acer platanoides and Robinia pseudoacacia in an industrial city (Northern Steppe of Ukraine)

The role of tree species as a tool for bioaccumulation of heavy metals is an important current issue within the context of the increase of anthropogenic pressure in urban ecosystems. The article presents the results of research on the level of soil contamination with heavy metals and the processes of their accumulation by native and introduced tree species in green spaces of Dnipro city. Inductively coupled plasma mass spectrometry (ICP-MS) was used to detect concentrations of heavy metals (Zn, Cu, Cd, Pb) in soil samples and the assimilation component in trees of black locust (Robinia pseudoacacia) and Norway maple (Acer platanoides). The ranges of mean concentrations of heavy metals at different study sites within the city’s green infrastructure were as follows (mg/kg): 30.7–185.5 for Zn, 5.7–22.4 for Cu, 9.0–31.3 for Pb, and 0.213–0.598 for Cd. With respect to all four of these metals, the soils of the Metallurgists Square location were characterized by the highest concentrations of the metals, and the Pridneprovsky Park in the area of the outskirts of Dnipro city was characterized by the lowest ones. Compared to soils, the two investigated tree species had a significantly lower content of all studied metals in leaves. The heavy metal accumulations in the leaves of both R. pseudoacacia and A. platanoides were observed in the following decreasing order: Zn > Cu > Pb > Cd. Regarding the migration of heavy metals in the soil-plant system, the concentrations of ecopollutants in the plants were found not to be dependent on their content in the soil environment. The calculated bioaccumulation coefficients of heavy metals for both tree species were < 1. However, the results of heavy metal concentration in leaves of both introduced and native tree species evidenced their special role in heavy metal bioaccumulation. Compared to R. pseudoacacia, such native species as A. platanoides can be considered to be a more “sensitive” bioindicator of environmental pollution caused by heavy metals. Planting fast-growing tree species such as R. pseudoacacia and A. platanoides can in a short time be an environmentally appropriate and cost-effective measure to mitigate the unfavourable effects of heavy metals on the environment

5-HT2 receptor binding, functional activity and selectivity in N-benzyltryptamines

The last fifteen years have seen the emergence and overflow into the drug scene of “superpotent” N-benzylated phenethylamines belonging to the “NBOMe” series, accompanied by numerous research articles. Although N-benzyl substitution of 5-methoxytryptamine is known to increase its affinity and potency at 5-HT2 receptors associated with psychedelic activity, N-benzylated tryptamines have been studied much less than their phenethylamine analogs. To further our knowledge of the activity of N-benzyltryptamines, we have synthesized a family of tryptamine derivatives and, for comparison, a few 5-methoxytryptamine analogs with many different substitution patterns on the benzyl moiety, and subjected them to in vitro affinity and functional activity assays vs. the human 5-HT2 receptor subtypes. In the binding (radioligand displacement) studies some of these compounds exhibited only modest selectivity for either 5-HT2A or 5-HT2C receptors suggesting that a few of them, with affinities in the 10–100 nanomolar range for 5-HT2A receptors, might presumably be psychedelic. Unexpectedly, their functional (calcium mobilization) assays reflected very different trends. All of these compounds proved to be 5-HT2C receptor full agonists while most of them showed low efficacy at the 5-HT2A subtype. Furthermore, several showed moderateto-strong preferences for activation of the 5-HT2C subtype at nanomolar concentrations. Thus, although some N-benzyltryptamines might be abuse-liable, others might represent new leads for the development of therapeutics for weight loss, erectile dysfunction, drug abuse, or schizophreniaThis work was supported by FONDECYT (Chile) regular research grants 1110146 and 1150868 to BKC and CONICYT doctoral grant 21140358 to MT-SS

Caracterización hidrogeoquímica de los manantiales del área geotermal de Ixtapan de la Sal-Tonatico (México)

La composición química del agua subterránea es el resultado de continuos procesos de interacción entre el agua de precipitación, que se infiltra en el terreno, y los minerales presentes en las rocas por donde circula. Parte de las características químicas del agua son adquiridas en la zona no saturada y otras más a lo largo de su recorrido dentro de la zona saturada, hasta donde pueden ser captadas o bien emerger como agua de manantial. Estos últimos según sus características, puede ser empleados para consumo humano, como generadores de energía o bien para fines recreativos, como es el caso de los manantiales termales de Ixtapan de la Sal y Tonatico. Los estudios hidrogeoquímicos de manantiales termales han permitido ampliar el conocimiento del origen, edad, composición físico-química de las aguas, de las condiciones de recarga y posibles mezclas de agua, así como identificar los procesos que tienen lugar en el acuífero y que permiten obtener una visión más completa del comportamiento del acuífero. También permiten deducir las características de la roca, composición mineralógica, textura, porosidad, grado de alteración, fracturación y compactación, tiempo de residencia o de contacto, temperatura y presión..

Organic aerosol formation from the reactive uptake of isoprene epoxydiols (IEPOX) onto non-acidified inorganic seeds

The reactive partitioning of cis and trans β-IEPOX was investigated on hydrated inorganic seed particles, without the addition of acids. No organic aerosol (OA) formation was observed on dry ammonium sulfate (AS); however, prompt and efficient OA growth was observed for the cis and trans β-IEPOX on AS seeds at liquid water contents of 40–75% of the total particle mass. OA formation from IEPOX is a kinetically limited process, thus the OA growth continues if there is a reservoir of gas-phase IEPOX. There appears to be no differences, within error, in the OA growth or composition attributable to the cis / trans isomeric structures. Reactive uptake of IEPOX onto hydrated AS seeds with added base (NaOH) also produced high OA loadings, suggesting the pH dependence for OA formation from IEPOX is weak for AS particles. No OA formation, after particle drying, was observed on seed particles where Na^+ was substituted for NH^(+)_(4). The Henry's Law partitioning of IEPOX was measured on NaCl particles (ionic strength ~9 M) to be 3 × 10^7 M atm^−1 (−50 / +100%). A small quantity of OA was produced when NH4+ was present in the particles, but the chloride (Cl-) anion was substituted for sulfate (SO^(2-)_(4)), possibly suggesting differences in nucleophilic strength of the anions. Online time-of-flight aerosol mass spectrometry and offline filter analysis provide evidence of oxygenated hydrocarbons, organosulfates, and amines in the particle organic composition. The results are consistent with weak correlations between IEPOX-derived OA and particle acidity or liquid water observed in field studies, as the chemical system is nucleophile-limited and not limited in water or catalyst activity

Predicting tuberculosis drug resistance with machine learning-assisted Raman spectroscopy

Tuberculosis (TB) is the world's deadliest infectious disease, with 1.5 million annual deaths and half a million annual infections. Rapid TB diagnosis and antibiotic susceptibility testing (AST) are critical to improve patient treatment and to reduce the rise of new drug resistance. Here, we develop a rapid, label-free approach to identify Mycobacterium tuberculosis (Mtb) strains and antibiotic-resistant mutants. We collect over 20,000 single-cell Raman spectra from isogenic mycobacterial strains each resistant to one of the four mainstay anti-TB drugs (isoniazid, rifampicin, moxifloxacin and amikacin) and train a machine-learning model on these spectra. On dried TB samples, we achieve > 98% classification accuracy of the antibiotic resistance profile, without the need for antibiotic co-incubation; in dried patient sputum, we achieve average classification accuracies of ~ 79%. We also develop a low-cost, portable Raman microscope suitable for field-deployment of this method in TB-endemic regions

Exploiting Anti-monotonicity of Multi-label Evaluation Measures for Inducing Multi-label Rules

Exploiting dependencies between labels is considered to be crucial for multi-label classification. Rules are able to expose label dependencies such as implications, subsumptions or exclusions in a human-comprehensible and interpretable manner. However, the induction of rules with multiple labels in the head is particularly challenging, as the number of label combinations which must be taken into account for each rule grows exponentially with the number of available labels. To overcome this limitation, algorithms for exhaustive rule mining typically use properties such as anti-monotonicity or decomposability in order to prune the search space. In the present paper, we examine whether commonly used multi-label evaluation metrics satisfy these properties and therefore are suited to prune the search space for multi-label heads.Comment: Preprint version. To appear in: Proceedings of the Pacific-Asia Conference on Knowledge Discovery and Data Mining (PAKDD) 2018. See http://www.ke.tu-darmstadt.de/bibtex/publications/show/3074 for further information. arXiv admin note: text overlap with arXiv:1812.0005

Is Violent Radicalisation Associated with Poverty, Migration, Poor Self-Reported Health and Common Mental Disorders?

BACKGROUND: Doctors, lawyers and criminal justice agencies need methods to assess vulnerability to violent radicalization. In synergy, public health interventions aim to prevent the emergence of risk behaviours as well as prevent and treat new illness events. This paper describes a new method of assessing vulnerability to violent radicalization, and then investigates the role of previously reported causes, including poor self-reported health, anxiety and depression, adverse life events, poverty, and migration and socio-political factors. The aim is to identify foci for preventive intervention. METHODS: A cross-sectional survey of a representative population sample of men and women aged 18-45, of Muslim heritage and recruited by quota sampling by age, gender, working status, in two English cities. The main outcomes include self-reported health, symptoms of anxiety and depression (common mental disorders), and vulnerability to violent radicalization assessed by sympathies for violent protest and terrorist acts. RESULTS: 2.4% of people showed some sympathy for violent protest and terrorist acts. Sympathy was more likely to be articulated by the under 20s, those in full time education rather than employment, those born in the UK, those speaking English at home, and high earners (>£75,000 a year). People with poor self-reported health were less likely to show sympathies for violent protest and terrorism. Anxiety and depressive symptoms, adverse life events and socio-political attitudes showed no associations. CONCLUSIONS: Sympathies for violent protest and terrorism were uncommon among men and women, aged 18-45, of Muslim heritage living in two English cities. Youth, wealth, and being in education rather than employment were risk factors

Learning Interpretable Rules for Multi-label Classification

Multi-label classification (MLC) is a supervised learning problem in which, contrary to standard multiclass classification, an instance can be associated with several class labels simultaneously. In this chapter, we advocate a rule-based approach to multi-label classification. Rule learning algorithms are often employed when one is not only interested in accurate predictions, but also requires an interpretable theory that can be understood, analyzed, and qualitatively evaluated by domain experts. Ideally, by revealing patterns and regularities contained in the data, a rule-based theory yields new insights in the application domain. Recently, several authors have started to investigate how rule-based models can be used for modeling multi-label data. Discussing this task in detail, we highlight some of the problems that make rule learning considerably more challenging for MLC than for conventional classification. While mainly focusing on our own previous work, we also provide a short overview of related work in this area.Comment: Preprint version. To appear in: Explainable and Interpretable Models in Computer Vision and Machine Learning. The Springer Series on Challenges in Machine Learning. Springer (2018). See http://www.ke.tu-darmstadt.de/bibtex/publications/show/3077 for further informatio