Analysis of the kinetics of surface reactions on a zinc oxide nanosheet-based carbon monoxide sensor using an Eley–Rideal model

Herein, we experimentally test a mathematical model of the reactions on the surface of a zinc oxide nanosheet-based carbon monoxide sensor. The carbon monoxide is assumed to react with surface oxygen via an Eley–Rideal mechanism, considering only the direct reaction between the two species. We demonstrate that the measured resistance responses of the system are well described by the model, facilitating further analysis of the physical rate constants in the system. By initially considering the system in the absence of any reducing gas, it is shown that various reaction parameters may be precisely estimated. For instance, fitting the model to response curves obtained at different temperatures shows the activation energy of the reaction between oxygen ions and carbon monoxide to be 54 ± 9 kJ mol−1, whereas the recovery curves yield an estimate of 42 ± 7 kJ mol−1. Similarly, the energy barrier for the formation of oxygen ions is found to equal 72 ± 9 kJ mol−1 from the sensor response and 63 ± 10 kJ mol−1 from the recovery. These estimates are in agreement with values quoted elsewhere in the literature, corroborating the validity of the model. In the absence of surface ions, the energy difference between the Fermi level and the conduction band minimum at the surface is estimated as 590 ± 90 meV

On the computational strength of pure ambient calculi

Cardelli and Gordon's calculus of Mobile Ambients has attracted widespread interest as a model of mobile computation. The standard calculus is quite rich, with a variety of operators, together with capabilities for entering, leaving and dissolving ambi- ents. The question arises of what is a minimal Turing-complete set of constructs. Previous work has established that Turing completeness can be achieved without using communication or restriction. We show that it can be achieved merely using movement capabilities (and not dissolution). We also show that certain smaller sets of constructs are either terminating or have decidable termination

Carbon nano-onions for biomedical applications

The biomedical applications of carbon nanomaterials are under intensive investigation for the development of next-generation therapeutics. Although much focus has been placed on carbon nanotubes (CNTs) and graphene, other carbon nanomaterials including carbon nanohorns (CNHs), nanodiamonds (NDs) and fullerenes have emerged as suitable candidates for biomedical applications. Among these multi-shell fullerenes, also known as carbon nano-onions (CNOs), are the less studied carbon nanomaterials in biomedicine. The unique properties of carbon nano-onions, such as high surface area-to-volume ratio, thermal conductivity, electrical conductance, mechanical stiffness and ease of chemical functionalization render them fascinating materials for diverse applications including drug-delivery, diagnostics, biological imaging and tissue engineering. Carbon nanomaterials are emerging as smart nanostructures for biomedicine due to the possibility to incorporate multiple functionalities and moieties internally or externally. They can be modified at a precise physicochemical level to optimize targeting in the complex in vivo environment and also engineered for fluorescence detection, magnetic resonance imaging and ablation of tumor cells. Herein, robust and versatile synthetic strategies for the modification of carbon nano-onions (CNOs) are reported. The development of novel CNO conjugates represent a promising platform for the realization of novel technology scaffold for molecular imaging, photodynamic therapy and molecular transporter of fully synthetic carbohydrate-based vaccines for immunotherapy due to the large specific surface area and unique optical and electrochemical properties of CNOs. Through the methodologies described, these smart nano-materials can envisage the realization of multi stimuli-responsive and dynamic architectures capable of changing their physicochemical behavior upon encountering specific microenvironmental signals becoming relevant for diagnosis, imaging and therapies of specific disease applications

High performance tunable piezoresistive pressure sensor based on direct contact between printed graphene nanoplatelet composite layers

This article details the development of a thin film piezoresistive screen printed pressure sensor on a flexible substrate using a composite ink based on functionalised graphene nanoplatelets (GNPs). The sensor operates through direct interfacial contact between two distinct films of the composite ink deposited over conductive substrates, without requiring any intermediate gap through spacers. The sensors showed consistent results and sensitivity forces ranging between 10 N to 2000 N. The piezoresistive range of the sensor can be tuned with the number of layers deposited per side

Modelling dynamic web data

We introduce Xd¼, a peer-to-peer model for reasoning about the dynamic behaviour of web data. It is based on an idealised model of semistructured data, and an extension of the ¼-calculus with process mobility and with operations for interacting with data. Our model can be used to reason about behaviour found in, for example, dynamic web page programming, applet interaction, and service orchestration. We study behavioural equivalences for Xd¼, motivated by examples

Abstract Domains for Type Juggling

Web scripting languages, such as PHP and JavaScript, provide a wide range of dynamic features that make them both flexible and error-prone. In order to prevent bugs in web applications, there is a sore need for powerful static analysis tools. In this paper, we investigate how Abstract Interpretation may be leveraged to provide a precise value analysis providing rich typing information that can be a useful component for such tools. In particular, we define the formal semantics for a core of PHP that illustrates type juggling, the implicit type conversions typical of PHP, and investigate the design of abstract domains and operations that, while still scalable, are expressive enough to cope with type juggling. We believe that our approach can also be applied to other languages with implicit type conversions

Effect of Maternal Obesity on Foetal Growth and Metabolic Health of the Offspring

Maternal and placental conditions that are unfavourable for the embryo/foetus have long-lasting effects on different tissues and functions of the body, which may persist for life and, potentially, also be transmitted to the offspring. This review resumes current evidence on principle maternal and gestational conditions associated with unfavourable metabolic programming of the offspring, along with their mechanisms of action, either supposed or already proved

Isolating JavaScript with Filters, Rewriting, and Wrappers

Abstract. We study methods that allow web sites to safely combine JavaScript from untrusted sources. If implemented properly, filters can prevent dangerous code from loading into the execution environment, while rewriting allows greater expressiveness by inserting run-time checks. Wrapping properties of the execution environment can prevent misuse without requiring changes to imported JavaScript. Using a formal semantics for the ECMA 262-3 standard language, we prove security properties of a subset of JavaScript, comparable in expressiveness to Facebook FBJS, obtained by combining three isolation mechanisms. The isolation guarantees of the three mechanisms are interdependent, with rewriting and wrapper functions relying on the absence of JavaScript constructs eliminated by language filters.