Vilnius Gediminas Technical University
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Kinetic Study of Peroxidase-Catalyzed Oxidation of 2-Hydroxyanthracene and 9-Phenanthrol in Presence of Biosurfactant Escin
Get PDFThe kinetics of fungal peroxidase-catalyzed 2-hydroxyanthracene and 9-phenanthrol oxidation was investigated in presence of biosurfactant escin at pH 5.5 and 25 °C. The kinetic measurements were performed using the fluorimetric method and the critical micelle concentration (CMC) of escin was determined using the dynamic light scattering technique. Inactivation of peroxidase was observed in absence of biosurfactant escin. It was shown that escin, used in concentrations lower than CMC, decreases or completely stops the peroxidase inactivation and increases the conversion of 2-hydroxyanthracene as well as of 9-phenanthrol. The environmentally friendly method of peroxidase-catalyzed 2-hydroxyanthracene and 9-phenanthrol oxidation in presence of biosurfactant Escin has an advantage over traditional decontamination methods due to their less environmental impact.This article belongs to the Section Biocatalysi
A Study on Tannery Sludge as a Raw Material for Cement Mortar
No full textThe paper analyses the properties (chemical and mineral composition, microstructure, density, etc.) of recycled tannery sludge (TS) and the possibilities for using it in cement mortar mixture. Mortar specimens containing 3–12% of tannery sludge by weight of cement and 3–9% of tannery sludge by weight of sand were tested. Flowability, density, ultrasonic pulse velocity (UPV), flexural and compressive strength, water absorption and sorptivity of the mortar were analysed. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis of tannery sludge and mortar are presented. The tests revealed that replacement of 6% of cement with tannery sludge in the mix increased flexural and compressive strength and UPV values, whereas water absorption decreased. SEM and XRD analysis revealed that specimens with tannery sludge contained lower amounts of ettringite and higher amounts of portlandite; the obtained structure was denser and contained more calcium hydrosilicates (C-S-H). Chromium leaching values in cement mortars were found not to exceed the limit values set forth in Directive 2003/33/EC.This article belongs to the Section Construction and Building Material
A Hybrid Fuzzy Group Multi-Criteria Assessment of Structural Solutions of the Symmetric Frame Alternatives
No full textStructural designers that design buildings use different criteria to select the frames’ materiality and structural solutions. Very often, the primary test is the cost of construction. Sometimes, solutions are determined by the terms of structure, architectural preferences, technological needs, fire safety requirements, environmental conditions, exploitation costs over the life of the building, ecological aspects, and experience, etc. This paper proposes an approach for analyzing the structural elements of buildings taking into account the impact on the environment using jointly incorporating subjective and objective aspects. The objective to combine the most important criteria into a single unit and carry out the overall assessment could be done by giving each variable a weighted value and perform a so-called multi-criteria analysis. This article shows the efficiency of the structural solution of the one-story building. The case study presents an investigation and comparison of five possible symmetrical structural solutions by multi-criteria assessment methods: The analysis of three steel frameworks differs majorly due to the beam-column characteristics, as well as precast RC frame structures case and combined steel beams and RC columns frame option. Possible solutions must meet all the essential requirements of the building, including mechanical resistance and stability. The obtained results show a broad assessment of the structural solutions of the building.This article belongs to the Special Issue Multi-Criteria Decision-Making Techniques for Improvement Sustainability Engineering Processe
Comparative Study of Urban Area Growth: Determining the Key Criteria of Inner Urban Development
No full textUrban population is steadily growing worldwide, while the number of people in Eastern Europe is decreasing. These two contradictory trends have outlined the proposal for sustainable solutions to solve civil engineering issues that are aimed at implementing the principles of sustainable development and ensuring a better quality of urban life. When considering the problem that is encountered in Eastern European countries, a multi-criteria model for sustainable urban development has been designed and focused on planning and simulating an inner urban living environment. The suggested model has disclosed the social, economic, environmental, and sustainable components of the infrastructure that are necessary for developing inner urban areas. The components have been adapted and presented in three different size territories covering Lithuanian cities and towns. The applied expert evaluation method has assisted in determining the key criteria that should be considered in order to identify the most important inner areas of urban development. It is expected that this study will extend activities that are performed in the field of improvement of sustainability engineering processes and offer guidelines for other researchers investigating the areas of inner urban development.This article belongs to the Special Issue Multi-Criteria Decision-Making Techniques for Improvement Sustainability Engineering Processe
An Extension of Fuzzy SWOT Analysis: An Application to Information Technology
Get PDFWhen considering today’s uncertain atmosphere, many people and organizations believe that strategy has lost its meaning and position. When future is predictable, common approaches for strategic planning are applicable; nonetheless, vague circumstances require different methods. Accordingly, a new approach that is compatible with uncertainty and unstable conditions is necessary. Fuzzy logic is a worldview compatible with today complicated requirements. Regarding today’s uncertain and vague atmosphere, there is an absolute requirement to fuzzify the tools and strategic planning models, especially for dynamic and unclear environment. In this research, an extended version of Strengths, Weaknesses, Opportunities and Threats (SWOT) fuzzy approach has been presented for strategic planning based on fuzzy logic. It has solved the traditional strategic planning key problems like internal and external factors in imprecision and ambiguous environment. The model has been performed in an information technology corporation to demonstrate the capabilities in real world cases.This article belongs to the Section Information System
Modification of the AFM Sensor by a Precisely Regulated Air Stream to Increase Imaging Speed and Accuracy in the Contact Mode
No full textIncreasing the imaging rate of atomic force microscopy (AFM) without impairing of the imaging quality is a challenging task, since the increase in the scanning speed leads to a number of artifacts related to the limited mechanical bandwidth of the AFM components. One of these artifacts is the loss of contact between the probe tip and the sample. We propose to apply an additional nonlinear force on the upper surface of a cantilever, which will help to keep the tip and surface in contact. In practice, this force can be produced by the precisely regulated airflow. Such an improvement affects the AFM system dynamics, which were evaluated using a mathematical model that is presented in this paper. The model defines the relationships between the additional nonlinear force, the pressure of the applied air stream, and the initial air gap between the upper surface of the cantilever and the end of the air duct. It was found that the nonlinear force created by the stream of compressed air (aerodynamic force) prevents the contact loss caused by the high scanning speed or the higher surface roughness, thus maintaining stable contact between the probe and the surface. This improvement allows us to effectively increase the scanning speed by at least 10 times using a soft (spring constant of 0.2 N/m) cantilever by applying the air pressure of 40 Pa. If a stiff cantilever (spring constant of 40 N/m) is used, the potential of vertical deviation improvement is twice is large. This method is suitable for use with different types of AFM sensors and it can be implemented practically without essential changes in AFM sensor design.This article belongs to the Section Physical Sensor
Identification of a 2′-O-Methyluridine Nucleoside Hydrolase Using the Metagenomic Libraries
Get PDFRibose methylation is among the most ubiquitous modifications found in RNA. 2′-O-methyluridine is found in rRNA, snRNA, snoRNA and tRNA of Archaea, Bacteria, and Eukaryota. Moreover, 2′-O-methylribonucleosides are promising starting materials for the production of nucleic acid-based drugs. Despite the countless possibilities of practical use for the metabolic enzymes associated with methylated nucleosides, there are very few reports regarding the metabolic fate and enzymes involved in the metabolism of 2′-O-alkyl nucleosides. The presented work focuses on the cellular degradation of 2′-O-methyluridine. A novel enzyme was found using a screening strategy that employs Escherichia coli uracil auxotroph and the metagenomic libraries. A 2′-O-methyluridine hydrolase (RK9NH) has been identified together with an aldolase (RK9DPA)—forming a part of a probable gene cluster that is involved in the degradation of 2′-O-methylated nucleosides. The RK9NH is functional in E. coli uracil auxotroph and in vitro. The RK9NH nucleoside hydrolase could be engineered to enzymatically produce 2′-O-methylated nucleosides that are of great demand as raw materials for production of nucleic acid-based drugs. Moreover, RK9NH nucleoside hydrolase converts 5-fluorouridine, 5-fluoro-2′-deoxyuridine and 5-fluoro-2′-O-methyluridine into 5-fluorouracil, which suggests it could be employed in cancer therapy.This article belongs to the Section Chemical BiologyThis research was funded by the Lithuanian Research Council (LMT) grant SEN-07/2015. This research was performed in cooperation with the INMARE consortium
Multiple Criteria Evaluation and the Inverse Hierarchy Model for Justifying the Choice of Rail Transport Mode
No full textThe choice of a particular mode of transport as an alternative to another one is subjective and usually based on an individual passenger’s approach to the evaluation of advantages and disadvantages of some particular means of transport. The paper presents the methods of analysing the reasons for passengers’ choice of travelling by train as an alternative to using air transport and the results obtained in the research. The 16 criteria (sub-criteria), describing the advantages of travelling by rail over air travel, are defined. The data of the survey questionnaire filled by 52 passengers of the Vilnius–Moscow train and the ranks assigned by them to the considered criteria are described. The average ranks of all 16 criteria and their normalized subjective weights are calculated by using a new method of average rank transformation into weight (ARTIW). The average ranks assigned by the passengers of the train to sub-criteria and the calculated global weights show what criteria are most important. Using the inverse hierarchy model based on the sub-criteria weights, the most and the least important groups of criteria are determined. The institutions and companies engaged in passenger transportation by rail, which give priority to improving the services described by the most important criteria, can make this mode of transport more attractive to people.This work is licensed under a Creative Commons Attribution 4.0 International License
Investigation of dilatancy mechanism of Portland cement paste
No full textThe increase in cement paste volume during the flowing has been determined by specially developed
equipment and the investigation methodology was proposed. Pressure (kPa), under which the cement
paste starts flowing, the average cement paste flow rate (cm/s), elastic deformation (%) and the increase
in cement paste volume due to redistribution of solid phase particles (%) were established in experimental tests of Portland cement pastes with different W/C ratio, Portland cement pastes with SiO2 microparticle suspension and quartz sand additive. With the increase of W/C ratio or liquid phase in cement pastes
the elastic deformation drops from 0.83% to 0.27%, while the volume of dispersion when the paste starts
flowing increases from 0.63% to 1.31% due to cement particle redistribution under shear stress. When
elastic rebound occurs, the volume of pastes with SiO2 microparticle suspension does not increase when
solid phase particles redistribute during the flow; dilatancy is not observed in the pastes with this
additive either or it is insignificant. When quartz sand particles of irregular size and large than cement
particles redistribute during the flow, the volume of the paste increases more (1.24–1.64%) and dilatancy
is observed in pastes with this additive. The test results confirm the earlier statements of researchers
stating that disperse systems are subject to dilatancy because of the increase of the system’s volume
under shear stress (during the flow), i.e. because of redistribution of the solid phase in the system
subjected to shear stress
Further exploration of the pavement oxidation model – Diffusion-reaction balance in asphalt
No full textOxygen diffusion and oxidative reaction are two main factors in asphalt oxidative aging discovered by
experiment, but the dynamic balance between them could not be easily studied by experimental methods due to its comprehensiveness. A pavement oxidation model was utilized to simulate this process in
asphalt: oxygen molecules penetrate into the asphalt film and then react with the asphalt molecules.
In some special cases, diffusion or reaction can become the determination step of asphalt oxidative
aging. Another factor, asphalt hardening, which is a result of oxidative reaction, slows the oxygen diffusion seriously and consequently. With the help of the model simulation, the efforts of binder reaction
kinetics, hardening properties and temperature on this balance have been studied and discussed in detail.
A new standard for asphalt binder, solely from oxidation aspect, includes high activation energy, low
hardening susceptibility and high hardening intercept. A new idea of anti-oxidant development was proposed. By decreasing oxygen diffusion, asphalt oxidation can be slowed down, but only works for oxygen
diffusion determined cases