Search results
1 – 10 of 956H. Stolarski, T. Belytschko, N. Carpenter and J.M. Kennedy
A simple triangular shell element which incorporates the effects of coupling between membrane and flexural behaviour and avoids membrane locking is described. The element uses a…
Abstract
A simple triangular shell element which incorporates the effects of coupling between membrane and flexural behaviour and avoids membrane locking is described. The element uses a discrete Kirchhoff bending formulation and a constant strain membrane element. For the purpose of permitting inextensional modes and thus avoiding membrane locking, a decomposition technique, which can also be viewed as a strain projection method, is used. The method is illustrated first for a beam element and then for a triangular shell element. Results are presented for a variety of linear static problems to illustrate its accuracy and some highly non‐linear problems to indicate its applicability to collapse analysis.
Piotr Firek, Michal Cichomski, Michal Waskiewicz, Ireneusz Piwoński and Aneta Kisielewska
The purpose of this paper is to present possibility of fast and certain identification of bovine serum albumin (BSA) by means of ion-sensitive field effect transistor (ISFET…
Abstract
Purpose
The purpose of this paper is to present possibility of fast and certain identification of bovine serum albumin (BSA) by means of ion-sensitive field effect transistor (ISFET) structures. Because BSA can cause allergic reactions in humans, it is one of reasons for development of sensitive sensors to detect residual BSA. BSA is commonly used in biochemistry and molecular biology in laboratory experiments. Therefore, to better understand the mechanism of signal transduction in simulated biological environment and to elucidate the role of adsorption of biomolecules in the generation of a signal at the interface with biological systems, the measurements of ISFET current response in the presence of BSA as a reference protein molecule were performed.
Design/methodology/approach
To fabricate transistors, silicon technology was used. The ISFET structures were coupled to specially designed double-side printed circuit board holder. After modification of the field effect transistor (FET) device with 3-aminopropyltriethoxysilane (APTES), a sensor with high sensitivity toward reference biomolecules was obtained. The current–voltage (I-V) characteristics of structures with and without gate modification were measured. Keithley SMU 236/237/238 measurement set was used. Deionized water solution and 0.05 per cent BSA were used.
Findings
In this research, a method of preparation of a biosensor based on a FET was developed. Sensitivity of APTES-modified FET device toward BSA as a biomolecule was investigated. I-V relationships of FET devices (with and without modification), being the effect of the interactions with the solution containing 0.05 per cent BSA, were measured and compared to the measurements performed for solutions without BSA.
Originality value
Compared to SiO2-containing ISFETs without modification or other different dielectrics, the application of APTES as the part of the membrane induced significant increase in their sensitivity to BSA.
Details
Keywords
Y.T. Lo, W.M. Leung and H.Z. Cui
Cracks in the roof parapet wall and damage to the waterproofing membrane are the common defects of roof construction that require frequent maintenance. This paper seeks to review…
Abstract
Purpose
Cracks in the roof parapet wall and damage to the waterproofing membrane are the common defects of roof construction that require frequent maintenance. This paper seeks to review the common defects of roof construction of medium‐rise buildings in sub‐tropical climates.
Design/methodology/approach
The research reported was carried out by the survey and analysis of 20 case study buildings. The modes of rooftop parapet wall dislocation are studied and the effects of thermal expansion and end conditions of the parapet wall on the damage to the waterproofing membrane are analysed.
Findings
Parapet wall dislocation failure is dependent on whether the ends are hinged or fixed. Failure usually leads to tearing of the waterproofing membrane.
Practical implications
Modification to the roof parapet wall design and to the selection of construction materials is suggested.
Originality/value
The modes of failure and proposed modification will be of interest to designers and those responsible for the maintenance of flat‐roofed buildings in sub‐tropical climates.
Details
Keywords
Lucie Zárybnická, Eliška Stránská, Kristýna Janegová and Barbora Vydrová
The study aims to focus on the preparation of a heterogeneous cation exchange membrane by a three-dimensional (3D) method – fused filament fabrication using a series of nozzles of…
Abstract
Purpose
The study aims to focus on the preparation of a heterogeneous cation exchange membrane by a three-dimensional (3D) method – fused filament fabrication using a series of nozzles of various diameters (0.4–1.0 mm). Polypropylene random copolymer (PPR) as a polymeric binder was mixed with 50 Wt.% of the selected conventional cation exchange resin, and a filament was prepared using a single screw mini extruder. Then filament was processed by FFF into the membranes with a defined 3D structure.
Design/methodology/approach
Electrochemical properties, morphology, mechanical properties and water absorption properties were tested.
Findings
Dependence of the tested properties on the used nozzle diameter was found. Both areal and specific resistances increased with increasing nozzle diameter. The same trend was also found for permselectivity. The optimal membrane with permselectivity above 90%, areal resistance of 8 O.cm2 and specific resistance of 124 O.cm2 was created using a nozzle diameter of 0.4 mm.
Originality/value
Using new materials for 3D print of cation exchange membrane with production without waste. The possibility of producing 3D membranes with a precisely defined structure and using a cheap 3D printing method. New direction of membrane structure formation. 3D-printed heterogeneous cation exchange membranes were prepared, which can compete with commercial membranes produced by conventional technologies. 3D-printed heterogeneous cation exchange membranes were prepared, which can compete with commercial membranes produced by conventional technologies.
Details
Keywords
Alan Leewood and Joop C. Nagtegaal
The application of the finite element method for the design and analysis of fabric structures is discussed. The basic concepts are outlined, and illustrated with practical…
Abstract
The application of the finite element method for the design and analysis of fabric structures is discussed. The basic concepts are outlined, and illustrated with practical structures designed and analysed with the MARC General Purpose Finite Element Program. Difficulties associated with the strongly anisotropic nature of the fabric are considered and solutions to overcome these problems are offered.
Jun Zhang, Xiaojian Ou, Lin Li, Qianqian Chen, Zifan Zhang, Ting Huo, Xiaoyu Lin, Fangfang Niu, Shengyuan Zhao, Fang We, Hui Li, Chunli Liu, Zhenbin Chen, Sujun Lu, Peng Zhang and Jinian Zhu
A novel grafted temperature-responsive ReO4− Imprinted composite membranes (Re-ICMs) was successfully prepared by using polyvinylidene fluoride (PVDF) resin membranes as…
Abstract
Purpose
A novel grafted temperature-responsive ReO4− Imprinted composite membranes (Re-ICMs) was successfully prepared by using polyvinylidene fluoride (PVDF) resin membranes as substrates, this study aimed to separate and purify ReO effectively.
Design/methodology/approach
Re-ICMs were synthesized by PVDF resin membranes as the substrate, acrylic acid (AA), acrylamide (AM), ethylene glycol dimethacrylate (EGDMA) were functional monomers. The morphology and structure of Re-ICMs were characterized by scanning electron microscope and Fourier transform infrared spectroscopy.
Findings
The maximum adsorption capacity toward ReO4− was 0.1,163 mmol/g and the separation decree had relation to MnO4− was 19.3. The optimal operation conditions were studied detailedly and the results as follows: the molar ratios of AA, AM, EGDMA, ascorbic acid, NH4ReO4, were 0.8, 0.96, 0.02, 0.003 and 0.006. The optimal time and temperature were 20 h and 40°C, respectively. The Langmuir and pseudo-second-order models were fit these adsorption characteristics well.
Practical implications
Rhenium (Re) is mainly used to chemical petroleum and make superalloys for jet engine parts. This study was representing a technology in separate and purify of Re, which provided a method for the development of the petroleum and aviation industry.
Originality/value
This contribution provided a novel method to separate ReO4− from MnO4−. The maximum adsorption capacity was 0.1163 mmol/g at 35°C and the adsorption equilibrium time was within 2 h. Meanwhile, the adsorption selectivity rate ReO4−/MnO4− was 19.3 and the desorption rate was 78.3%. Controlling the adsorption experiment at 35°C and desorption experiment at 25°C in aqueous solution, it could remain 61.3% of the initial adsorption capacity with the adsorption selectivity rate of 13.3 by 10 adsorption/desorption cycles, a slight decrease, varied from 78.3% to 65.3%, in desorption rate was observed.
Details
Keywords
Ilhem Ghodbane, Rochdi Kherrrat, Saida Zougar, Rim Lamari, Redouane Haddadji and Mohamed Saleh Medjram
The purpose of this work is to explore electrical properties of an electrochemical sensor designed for the detection of malachite green (MG) present in an aqueous solution.
Abstract
Purpose
The purpose of this work is to explore electrical properties of an electrochemical sensor designed for the detection of malachite green (MG) present in an aqueous solution.
Design/methodology/approach
The present sensor consists in the spatial coupling of a polymeric membrane and an ion-sensitive electrode (platinum electrode). The preparation of the polymeric membrane involves the incorporation of an ionophore (D2HPA), a polymer (polyvinylchloride [PVC]) and a plasticizer (dioctyl phthalate [DOP]). Several techniques have been used to characterize this sensor: the cyclic voltammetry, the electrochemical impedance spectroscopy and the optical microscopy. The sensibility, the selectivity and the kinetic study of a modified platinum electrode have been evaluated by cyclic voltammetry.
Findings
The obtained results reveal the possibility of a linear relationship between the current of reduction peaks and MG concentration. A linear response was obtained in a wide-concentration range that stretches from 10−5 to 10−13 mol L−1, with a good correlation coefficient (0.976) and a good detection limit of 5.74 × 10−14 mol L−1 (a signal-to-noise ratio of 3). In addition, the voltammetric response of modified electrode can be enhanced by adding a layer of Nafion membrane. Under this optimal condition, a linear relationship was obtained, with a correlation coefficient of 0.986 and a detection limit of 1.92 × 10−18 mol L−1.
Originality/value
In the present research, a convenient, inexpensive and reproducible method for the detection of MG was developed. The developed sensor is capable of competing against the conventional techniques in terms of speed, stability and economy.
Details
Keywords
Presents consciousness as not only cognitive awareness in sensory, imaginational, remembered and dream contexts, but also as the awareness in all of us that is not necessarily…
Abstract
Presents consciousness as not only cognitive awareness in sensory, imaginational, remembered and dream contexts, but also as the awareness in all of us that is not necessarily accessed by or immediately accessible only to the conscious mind. Sees consciousness, because of its primal and pervasive nature, as the Holy Grail of the scientific quest. Provides examples of how it can be misunderstood and exposed to sources of confusion. Discusses the resulting scenarios and considers global re‐assessments, including one of evolutionary theory.
Details
Keywords
Late life depression is often associated with a poor response to antidepressants; therefore an alternative strategy for therapy is required. Although several studies have reported…
Abstract
Late life depression is often associated with a poor response to antidepressants; therefore an alternative strategy for therapy is required. Although several studies have reported that phosphatidylserine (PS) may be effective for late life depression and that omega-3 fatty acids DHA and EPA have also proven beneficial for many higher mental functions, including depression, no concrete conclusion has been reached. This study was performed to clarify the effect of PS and omega-3 fatty acid-containing supplement for late life depression by not only clinical evaluation but also salivary cortisol levels. Eighteen elderly subjects with major depression were selected for the study. In all, insufficient improvement had been obtained by antidepressant therapy for at least 6 months. The exclusion criteria from prior brain magnetic resonance images (MRI) included the presence of structural MRI findings compatible with stroke or other gross brain lesions or malformations, but not white matter hypersensitivities. They took a supplement containing PS 100 mg, DHA 119 mg and EPA 70 mg three times a day for 12 weeks. The effects of the supplement were assessed using the 17-item Hamilton depression scale (HAMD17) and the basal levels and circadian rhythm of salivary cortisol. The study adopted them as indices because: salivary cortisol levels are high in patients with depression, their circadian rhythm related to salivary cortisol is often irregular, and these symptoms are alleviated as depression improves. The mean HAM-D17 in all subjects taking the supplement was significantly improved after 12 weeks of taking the supplement. These subjects were divided into 10 non-responders and 8 responders. The basal levels and circadian rhythm of salivary cortisol were normalized in the responders while not in non-responders. PS and omega-3 fatty acids, or other elements of the supplement, may be effective for late life depression, associated with the correction of basal levels and circadian rhythm of salivary cortisol.
Details
Keywords
Konstantin Vishnevskiy and Andrei Yaroslavtsev
The purpose of this paper is to apply Foresight methodology to the area of nanotechnologies and new materials within the framework of Russian S&T Foresight 2030 aimed at…
Abstract
Purpose
The purpose of this paper is to apply Foresight methodology to the area of nanotechnologies and new materials within the framework of Russian S&T Foresight 2030 aimed at revelation of major trends, most promising products and technologies.
Design/methodology/approach
To achieve this goal, best international practice was analyzed that provided a solid basis for Russian S&T Foresight 2030 (section “Nanotechnology and new materials”). The study used a wide range of advanced Foresight methods adapted to Russian circumstances. During the Foresight study, the authors integrated “market pull” and research “technology push” approaches including both traditional methods (priority-setting, roadmaps, global challenges analysis) and relatively new approaches (horizon scanning, weak signals, wild cards, etc.).
Findings
Using the methods of the Foresight, the authors identified trends with the greatest impact on the sphere of nanotechnology and new materials, promising markets, product groups and potential areas of demand for Russian innovation technologies and developments in this field. The authors assessed the state-of-the-art of the domestic research in the area of nanotechnologies and new materials to identify “white spots”, as well as parity zone and leadership, which can be the basis for integration into international alliances and positioning of Russia as a center of global technological development in this field.
Originality/value
The results of applying Foresight methodology toward revelation of the most prospective S&T areas in the field of nanotechnologies and new materials can be used by a variety of stakeholders including federal and regional authorities, technology platforms and innovation and industrial clusters, leading universities and scientific organizations in formulation of their research and strategic agenda. Russian businesses including both large companies and small and medium-sized enterprises can use results of the study in creating their strategic R&D programs and finding appropriate partners.
Details