Local pH variation as an initial step in bacterial surface-sensing and biofilm formation

The development of surface-associated layers of matrix-embedded microbial populations, called biofilms, is a serious problem in many medical and industrial settings. These contaminations are difficult to eradicate because of the high resistance level acquired by the cells in their particular environment. From the very beginning of the colonization process, modifications of gene expression are observed and could, at least partially, explain biofilm resistance. In order to develop anti-biofilm molecules and surface treatments, it is of pivotal importance to identify the physico-chemical parameters which activate the sensor systems of pioneering microbes when they come into contact with a surface. The aim of our study was to examine the pH variations in the local micro-environment created between the cell layer and the surface after bacteria adhesion. Using an ion-sensitive field effect transistor (ISFET), as a substratum, colonized by a curli hyperproducing strain known to form biofilms, we observed that the evolution of the pH change was significantly different in the micro-compartment in contact with the electrochemical sensor compared to that within the liquid phase.     

Multi‐threshold and multi‐input DNA logic design style for profiling the microRNA biomarkers of real cancers

Early detection of cancer is very critical because it can reduce the treatment risk and cost. MicroRNAs (miRNAs) have been introduced in recent years as an efficient class of biomarkers for cancer early detection. Now, real‐time polymerase chain reaction has been used to profile the miRNA expression, which is costly, time consuming and low accuracy. Most recently, DNA logic gates are used to detect the miRNA expression level that is more accurate and faster than previous methods. The DNA‐based logic gates face with serious challenges such as the large complexity and low scalability. In this study, the authors proposed a methodology to design multi‐threshold and multi‐input DNA‐based logic gates in response to specific miRNA inputs in live mammalian cells. The proposed design style can simultaneously recognise multiple miRNAs with different rising and falling thresholds. The design style has been evaluated on the lung cancer biomarkers and the experimental results show the efficiency of the proposed method in terms of accuracy, efficiency and speed.Inspec keywords: DNA, logic design, biocomputing, RNA, molecular biophysics, logic gates, lung, genetics, cellular biophysics, cancer, biology computing, enzymes, biosensorsOther keywords: falling thresholds, specific miRNA inputs, multiinput DNA‐based logic gates, low scalability, DNA‐based logic gates face, miRNA expression level, DNA logic gates, low accuracy, time consuming, real‐time polymerase chain reaction, cancer early detection, treatment risk, cancers, microRNA biomarkers, multiinput DNA logic design style, multithreshold, lung cancer biomarkers     

Optimization of a dual cycle cogeneration system based on a new exergetic performance criterion

An ecological performance analysis for an irreversible dual-cycle cogeneration system has been performed. The objective function is called as the exergetic-performance coefficient (EPC) and defined as the ratio of total exergy output to the loss rate of availability. The general and optimal performances of the irreversible dual-cycle cogeneration system, having a finite-rate of heat transfer, heat leak and internal irreversibilities based on the EPC objective function have been investigated. Comparisons with respect to the optimal total-exergy output are also provided in order to establish the utility of the new exergetic-performance coefficient. The analyzed results of the dual-cycle cogeneration system considered, working at maximum EPC conditions, have a significant advantage in terms of entropy-generation rate and can be used for the selection of optimal design parameters.     

Properties of Hg1−x Zn x Te solid solutions

Hg_1–x ZN _x Te alloys were prepared by inter-diffusion at high temperatures using mixtures of HgTe and ZnTe compounds in the form of compressed powders. The lattice constant was determined using X-ray diffraction measurements and was found to exhibit a linear dependence onx over the entire composition range. Diffused reflectance measurements as a function of wavelength yielded values of the energy bandgap that agree closely with those reported previously on single crystals. The room temperature electrical conductivity and thermoelectric power were measured as a function ofx. Intrinsic conduction was found to dominate for 0<x<0.3. In this composition range the thermoelectric power was negative due to the high ratio of electron to hole mobilities.     

Resonance in cylindrical-rectangular and wraparound microstripstructures

A rigorous analysis of the resonance frequency problem of both the cylindrical-rectangular and the wraparound microstrip structure is presented. The problem is formulated in terms of a set of vector integral equations. Using Galerkin's method to solve the integral equations, the complex resonance frequencies are studied with sinusoidal basis functions which incorporate the edge singularity. The complex resonance frequencies are computed using a perturbation approach. Modes suitable for resonator or antenna applications are investigated. The edge singularity of the patch current is shown to have no significant effect on the accuracy of the results. It is shown that the HE₁₀ modes of the cylindrical-rectangular and wraparound patches are more appropriate for resonator applications. The HE₀₁ and TE ₀₁ modes of the cylindrical-rectangular and wraparound patches, respectively, are efficient radiating modes     

Hierarchical time-based information release

Rapid distribution of newly released confidential information is often impeded by network traffic jams, especially when the confidential information is either crucial or highly prized. This is the case for stock market values, blind auction bidding amounts, many large corporations'strategic business plans, certain news agencies'timed publications, and some licensed software updates. Hierarchical time-based information release (HTIR) schemes enable the gradual distribution of encrypted confidential information to large, distributed, (potentially) hierarchically structured user communities, and the subsequent publication of corresponding short decryption keys, at a predetermined time, so that users can rapidly access the confidential information. This paper presents and analyzes the efficiency of a novel HTIR scheme. Deholo Nali holds a M.Sc. in mathematics and a Ph.D. in Computer Science from the University of Ottawa, Canada. In the past, he worked for two years as a software developer and pursued research in the design and analysis of identity-based cryptographic protocols. His research interests now include identity theft and graphical password authentication.     

The thermal kinetics of texture change and the analysis of texture variability for raw and roasted hazelnuts

Texture changes of hazelnuts which were dry roasted at temperatures from 120 to 180 °C, for durations ranging from 5 up to 60 min, were studied using instrumental analysis. The textural changes in hazelnuts were represented by the fracture force obtained from compression tests. The magnitudes of the parameters for the corresponding texture change model were determined using one step non‐linear regression. The order of the reaction was found by plotting isothermal curves of texture response against time; statistical analysis of the data showed that it was best represented by a first‐order reaction. The rate constants were assumed to have an Arrhenius‐type dependence on temperature. The activation energy and the frequency (pre‐exponential) factor at a reference temperature (150 °C) were determined to be 39.25 kJ mol^?1 and 0.0421 s^?1, respectively. Young's modulus and the fracture stress for roasted hazelnuts were calculated to be 4.93 and 1.54 MPa, respectively. Both roasting temperature and time had significant effects on the textural changes in hazelnuts, and the variability in the texture decreased during the roasting process. The physical properties of hazelnuts were correlated with the texture response. A possible major factor causing the high variability in texture was the internal cavity present at the core of each hazelnut. The development of a model of the thermal kinetics of texture change over a large roasting temperature and time range should allow optimization studies to be used for determining the best roasting schedule in terms of delivering the required product texture.     

Effects of chemical surface pretreatment on tensile properties of a single glass fiber and the glass fiber reinforced epoxy composite

The aim of this article is to determine the effect of surface pretreatments, prior to the silanization, on the structure and tensile properties of the glass fibers and their epoxy composites. Commercial glass fibers were washed with acetone to remove the soluble portion of sizing, calcinated for the removal of organic matter, activated for surface silanol regeneration, and silanizated with glycidoxypropyltrimethoxysilane (GPS). Tensile test was carried out. The morphology of pretreated glass fibers and the fracture surfaces of the epoxy composites were observed with a scanning electron microscope (SEM). The results revealed that both apparent modulus and strength of a single glass fiber and the glass fiber/epoxy resin composites strongly depend on the fiber surface pretreatments. The acetone treatment did not change appreciably the composition and tensile properties of glass fibers, but there was a weak interface between fibers and matrix. In calcinated and acid activated fibers, the two competitive effects was observed: (1) degradation of the fibers themselves and (2) improved interfacial adhesion between the glass fibers and the epoxy matrix, once the samples was silanizated. The ATR‐FTIR results show that the surface content of Si OH increases as reflected by the increasing of the Si O band, resulting in an interaction between silane coupling agent and glass fiber. POLYM. COMPOS., 91–100, 2016. © 2014 Society of Plastics Engineers