Disposable genosensor, a new tool for the detection of NOS-terminator, a genetic element present in GMOs

Legislation enacted worldwide to regulate the presence of genetically modified organisms (GMOs) in crops, foods and ingredients, necessitated the development of reliable and sensitive methods for GMO detection. An indicator based electrochemical disposable genosensor for the voltammetric detection of NOS-terminator, a genetic element present in GMOs is described as a possible substitute method for the common technique of gel electrophoresis and fluorescent image analysis. The biosensor relies on the immobilization of the 25-mer single stranded oligonucleotides (probe) related to NOS-terminator DNA sequence and the relative binding of this sequence with the polymerase chain reaction (PCR) amplified samples from certified reference material (CRM) of Roundup Ready soybean (Fluka) at a screen printed electrode (SPE). The extent of hybridization between the probe and target DNA is determined by using square wave voltammetry (SWV) with moving average baseline correction and methylene blue (3,7-bis(dimethylamino)phenothiazin-5-ium chloride, MB), as the hybridization indicator. The difference between the MB signals, obtained from the hybrid modified and probe modified SPEs, is used to detect GMOs from PCR amplified DNA samples. Numerous factors affecting the hybridization and indicator binding reactions are optimized to maximize the sensitivity.     

Structural analysis of conical carbon nanofibers

Conical carbon nanofibers are a relatively new type of carbon nanomaterial that has received considerable scientific and commercial interest due to its physical properties. However, its structure and growth mechanism have still not been determined conclusively. In this study the structure of these materials was investigated employing molecular models and structural analyses and compared with reported experimental observations, principally of cone apex angles. The results showed that stacked cone models could not explain the wide variety of apex angles observed for these nanofibers and related structures. Cone-helix models, originally proposed for other carbon conical structures, allow a variety of apex angle structures and were found to be applicable for nanofibers as well. An equation was developed that allows for prediction of cone-helix structures with good graphitic alignment. Such structures were also shown to be more compatible with the physical properties and growth mechanism of nanofibers than stacked cone structures. From these results a cone-helix structure, and a new cone-helical growth mechanism for the nanofibers based on heterogeneous nucleation on conical catalyst particles, are proposed.     

Crystallization kinetics and affecting parameters on polycaprolactone composites with inorganic and organic additives

The isothermal crystallization and mechanical behavior of biodegradable polycaprolactone (PCL) composites with organic (oleic acid and glycerol monooleate) and inorganic (zinc oxide, organoclay, and hydroxy apatite) additives used alone or simultaneously were investigated. The effect of all additives on the degree of crystallinity percentage (DOC%), isothermal crystallization kinetics parameters, and mechanical test results of PCL composites was studied. The PCL composite films were prepared by solvent casting by using dichloromethane as the solvent. The films were characterized by X‐ray diffraction, differential scanning calorimetry (DSC), and tensile tests. DSC of the first melting and X‐ray diffraction DOC% results (for composites by solvent casting) are compatible. The values by DSC of the second melting (for composites by extrusion method) are lower. Organoclay gives the highest crystallinity among the other inorganic additives used. Small amounts of inorganic additives act as a nucleating agent and increase the crystallinity; the higher amounts decrease. The organic additives act as the plasticizer. When used alone, it lowers the crystallinity, but when used with inorganic additives, it improves the dispersion of inorganic particles in the polymer matrix. The isothermal crystallization kinetics parameters by Avrami analysis showed that crystallization was controlled by nucleation and the crystals had spherical structure. The nucleation type changed between thermal and athermal nucleation. The Pukanzky model interaction parameter B indicated that the organic additives improved the dispersion of inorganic particles in the polymer matrix. Statistically significant, eight correlations (F > 6) were obtained for the crystallinity, crystallization parameters, Young's modulus, and tensile strength as a function of concentration of additives. J. VINYL ADDIT. TECHNOL., 21:174–182, 2015. © 2014 Society of Plastics Engineers     

Thermal,morphological, and spectral changes after Er,Cr:YSGG laser irradiation at low fluences on primary teeth for caries prevention

The aim of this study was to determine the temperature increase in the pulp chamber and possible thermal effects on molecular structure of primary teeth during the irradiation with Er,Cr:YSGG laser. Primary central incisors were divided into three groups (n = 20). Labial surfaces in each group were irradiated by Er,Cr:YSGG laser within different power and frequencies as following groups: I: 0.25 W, 20 Hz, II: 0.50 W, 20 Hz, III: 0.75 W, 20 Hz. A thermocouple was placed inside the pulp chamber so that the temperature increments were recorded during the enamel irradiation. Morphological changes of enamel surfaces were experimentally evaluated by SEM. Fourier‐transform infrared spectroscopy and RAMAN analyses were carried out to determine the differentiations in the molecular structure. The experimental results obtained were analyzed statistically by means of one‐way analysis of variance. Statistically significant differences were detected between groups (p < .05). Group III exhibited the highest values for the temperature parameters. Besides, the conical craters, cracks, and formation of ablation areas were observed for all the groups. Also, it was obtained that the hydroxyapatite lost the hydroxyl ions due to the thermal effect of the laser. Temperature rise throughout the Er,Cr:YSGG laser irradiation for prevention of primary enamel demineralization presented a positive correlation with the laser output power level. The formations of adverse morphological and spectral changes were detected on the surface of teeth after the laser application. On this basis, the Er,Cr:YSGG laser applications should be treated with much more caution considering enamel surface and pulpal tissues in primary teeth.     

Study of zeolite influence on analytical characteristics of urea biosensor based on ion-selective field-effect transistors

A possibility of the creation of potentiometric biosensor by adsorption of enzyme urease on zeolite was investigated. Several variants of zeolites (nano beta, calcinated nano beta, silicalite, and nano L) were chosen for experiments. The surface of pH-sensitive field-effect transistors was modified with particles of zeolites, and then the enzyme was adsorbed. As a control, we used the method of enzyme immobilization in glutaraldehyde vapour (without zeolites). It was shown that all used zeolites can serve as adsorbents (with different effectiveness). The biosensors obtained by urease adsorption on zeolites were characterized by good analytical parameters (signal reproducibility, linear range, detection limit and the minimal drift factor of a baseline). In this work, it was shown that modification of the surface of pH-sensitive field-effect transistors with zeolites can improve some characteristics of biosensors.     

Formalism for Detecting Version Differences in Data Models

In the architecture/engineering/construction (AEC) industry, a large number of data models (e.g., data exchange standards and task-specific data models) have been created and utilized to represent and exchange data in software packages. To meet the ever-expanding requirements for modeling real world information, the data models need to be updated frequently. Accordingly, those who need to implement these data models in their AEC-related software which often requires that they possess civil engineering domain knowledge, have to change their existing implementations for compliance with these models to account for the latest update. Before adopting changes of such data models, those developers working at AEC-related software companies must precisely identify which parts of the data models have been modified in a new release. Given the growing scale and complexity of today’s data models involved in the AEC domain, identification of differences in two versions of a data model is a time-consuming and error-prone process, when performed manually. A semiautomated approach that identifies the differences in two versions of a data model could enable a rapid update of existing implementations of the model in AEC-related software. Due to the likelihood of having some commonality between the two versions of a model, it is possible to automatically identify version differences accurately. In this paper, we present an approach for detecting the differences between two releases of the same data model accurately and efficiently. This approach incorporates taxonomy for describing possible differences between two versions of a data model and provides a way to classify these differences. A prototype is implemented and used to validate the approach with the recent releases of some real world data models. The approach developed in this paper can help AEC-related software developers adopt and implement data models in their software systems.     

Rapid and catalytic pyrolysis of corn stalks

Non-catalytic and catalytic rapid pyrolysis of corn stalks was studied in a tubular fixed-bed reactor. The optimum operating conditions giving the highest liquid yield was determined as pyrolysis temperature of 500 °C, sweeping gas flow rate of 400 cm³ min^− 1 and heating rate of 500 °C min^− 1. In the catalytic process, rapid pyrolysis of stalks was performed at the optimum conditions with catalysts such as ZSM-5, HY and USY. The highest liquid yield from the catalytic pyrolysis was 27.55% with ZSM-5, while the oil from non-catalytic pyrolysis was 33.30%. In the last part, various spectroscopic and chromatographic methods were applied for characterization of bio-oils. Although catalytic pyrolysis converts the long chains of alkanes and alkenes of the oils into lower weight hydrocarbons, the obtained oil yields were lower than those of non-catalytic pyrolysis. USY catalyst gives the highest amount of aromatics among the catalysts used. Moreover, TG–DTA analyses were applied on raw materials to investigate thermal degradation of corn stalks and calculate the kinetic parameters.     

Characterization and Search of Construction Inspection Plan Spaces Developed Using a Component-Based Planning Approach

Formal construction inspection planning is needed to help reduce the incidence of overlooked or inefficient inspections, and to help realize the potential of emerging sensing technologies. Prior publications by the authors have presented requirements for such an approach and a component-based inspection planning implementation as an approach in addressing some of the requirements towards formal construction inspection planning. Implementation of such a component-based approach for typical construction examples, however, leads to the generation of large, rugged search spaces. This paper first describes the characteristics of search spaces that are generated using a component-based approach to illustrate which search mechanisms are appropriate to explore these search spaces. The paper then describes a set of search algorithms and heuristics that were investigated and evaluated for searching construction inspection plans. Specific discussions on how these algorithms performed in searching within inspection planning spaces are provided based on experiments conducted using a testbed characterizing a construction site and a building performance monitoring decision-making example.     

Oxidation States and the Acidity of Ordered Arrays of Co–Pb Mixed Oxide Nanoparticles Templated in SBA15

Co, Pb and CoPb containing SBA15 mesoporous materials were prepared by direct synthesis method. When Co and Pb were loaded simultaneously, nanoparticles were formed in the channels of SBA15 as observed by transmission electron microscopy. These nanoparticles blocked the pores and decreased the apparent surface areas indicated by BET analysis. Pyridine adsorption on these catalysts revealed that while monometallic additions did not influence the overall acidity of SBA15, in the bimetallic system, characteristic bands due to pyridine adsorption on Co²⁺ ions were observed.