Periodica Polytechnica (Budapest University of Technology and Economics)
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Does Vinblastine Retain its Anticancer Effect in the Presence of Cyclodextrin? A Preliminary Study
Get PDFVinblastine was investigated in the presence of cyclodextrin derivatives on different cancer cells and it was established that the anticancer activity was unchanged. This was the first step of a long procedure resulting in the dosage of vinblastine together with cyclodextrin or its derivatives to improve the adverse effects
A Green Synthetic Strategy for Pyrazolo[1,5-a]pyrimidin-7(4H)-one Derivatives by the Reaction of Aminopyrazoles and Symmetric/Non-symmetric Alkynes Assisted by KHSO4 in Aqueous Media
Get PDFPyrazolo[1,5-a]pyrimidine and its derivatives possess important pharmacological properties and hence they have drawn substantial attention as a privileged scaffold to design and explore novel drugs in medicinal chemistry. We herein report a green synthetic approach for a library of pyrazolo[1,5-a]pyrimidin-7(4H)-one derivatives under ultrasonic irradiation which is one of the green approaches to minimize environmental impact in synthetic organic chemistry.Aminopyrazoles were reacted with symmetric and non-symmetric alkynes assisted by KHSO4 under the influence of US in aqueous ethanol to give pyrazolo[1,5-a]pyrimidines in good yields. This strategy worked well with dimethyl acetylenedicarboxylate (DMAD) and ethyl/methyl propiolate and the corresponding products were obtained in good yields. The structures of the products were well established with the help of their analytical and spectral data (1H NMR, 13C NMR, FT-IR, MS)
Antioxidant Effects and Fatty Acid Analysis of Leucojum aestivum Seed Coat Extracts
Get PDFThe aim of this study is to analyze the biochemical composition and antioxidant activity of Leucojum aestivum seed coats. In the crude extract the total phenolic content was determined to be 129.55 ± 1.94 mg gallic acid equivalent (GAE)/g, while the total flavonoid content was found to be 210.21 ± 7.91 mg quercetin equivalent (QE)/g. Additionally, the total flavonol, tannin, and proanthocyanidin contents were determined to be 9.63 ± 5.16 mg QE/g, 3.32 ± 0.14 mg GAE/g, and 129.89 ± 6.10 mg catechin equivalent (CAE)/g, respectively. Furthermore, the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity showed a significant antioxidant potential with a concentration that results in 50% decrease in the initial DPPH concentration IC50 value of 214.97 ± 50.44 mg QE/g in the crude extract. GC/MS analysis revealed the presence of various biologically active compounds, including hexadecanoic acid, oleic acid, and stigmasterol. Moreover, galantamine and galathan were identified in the seed coat extracts. Fatty acid analysis indicated the presence of compounds such as linoleic acid, oleic acid, and palmitic acid. This comprehensive study provides a detailed examination of seed coats and highlights the presence of biologically active compounds such as galantamine. This finding represents a study conducted for the first time in the literature, as no similar research focusing on L. aestivum seed coats has been conducted previously. Therefore, the results of the study provide new insights into the potential biological and pharmacological effects of seed coats and offer significant findings that could serve as a basis for future research
Evaluation of Material Characteristics and Structural Dynamic Properties of a Historical Church: The Case of 19th Century Bursa Derekoy Church (Ayia Paraskevi)
Get PDFDerekoy (Ayia Paraskevi) Church, built by the Orthodox Greeks in Bursa, is one of the prominent monuments built in the 19th century. The structure, which lost its community with the population exchange (1923) between Turkey and Greece, has since then been out of service and a rapid deterioration process has begun. Analysis works are frequently implemented for this purpose and become crucial in Turkey, of which a large part is within the earthquake zone. However, the majority of the studies on the preservation of historical buildings are lacking in detailed material analysis and numerical methods. Conducting a series of material tests and numerical analyses for the structure provides more reliable and qualified interventions since they influence the decisions on the reinforcement and protection methods employed for historical buildings. For this purpose, the material characterizations of the mortar, plaster and stones used in the church were carried out by performing physical, chemical, mechanical, petrographic and mineralogical tests on samples taken from the church. Afterwards, mechanical tests of the walls and vibration tests were conducted to determine the dynamic behavior of the building. Based on the results obtained from the analyses, a series of intervention methods were proposed. It is understood that the flat-jack, shear and vibration tests are vital for determining the real structural behavior of the building. Furthermore, it is recommended that vibration tests are carried out on both the overall structure and individual walls to determine the dynamic behavior of similar structures where only outer walls remain standing
The Effect of Freeze-thaw on Mechanical and Ultrasonic Properties of Hungarian Oolitic Stones
Get PDFThe freeze-thaw process is a weathering phenomenon that occurs in rocks and stones when water enters small cracks and pores within the stone. When the temperature drops below freezing, the water inside the rock expands as it freezes, exerting pressure on the rock from within. In this study the effect of freeze thaw on mechanical parameter uniaxial compression strength (UCS) and ultrasonic pulse velocity (UPV) of 47 oolitic samples were considered. At first, capillary absorption for cylindrical and prismatic oolitic samples were measured and then freeze-thaw experiment with 23 cycles were applied to the samples. UPV of samples before and after freeze-thaw was analysed by two ultrasonic devices including Geotron and Pundit. It was observed that freeze thaw decreases primary velocity (Vp) and secondary velocity (Vs) by around 20 and 7% respectively. However, average UCS of 1.6 MPa indicates strength decrease of samples, which represent negative effect of pore expansion due to freeze thaw on strength parameter of samples
Influence of Sustainable Grout Material on the Moisture Damage of Semi-flexible Pavement
Get PDFSemi-flexible pavement (SFP), also known as grouted pavement, is a type of pavement structure consisting of a porous asphalt skeleton with air voids between 25 and 35% injected with cementitious grout materials. The special skeleton of SFP provided enhanced durability and resilience, making it a promising option for the construction of road surfaces in high-traffic areas and severe conditions. The main aim of the current research is to investigate the rutting behavior and moisture resilience of SFP-containing sustainable grout using ceramic waste powder (CWP). This research introduced the use of CWP as a replacement for conventional grout (cement) in SFP for the first time. CWP partially replaced cement at ratios of 15, 20, 30, 40, and 50% of the cement weight. Indirect Tensile Strength (ITS) and Hamburg Wheel Tracking Tests (HWTT) were used to evaluate the performance of SFP to reduce the detrimental effect of moisture. The grout modified with CWP shows excellent results in the ITS and Tensile Strength Ratio (TSR), and all modified SFP mixtures give higher values in these tests compared with Control Mix (CM). In the HWTT, the minimum rut depth of the modified SFP was 2.8 mm and 3.10 mm. Compared to CM, rutting decreased by 73%–76% for CWP mixes with 20% and 30% replacement. This indicates the high fluidity of CWP, which enabled it to penetrate all voids in the porous pavement (PA) and form a dense microstructure due to its excellent pozzolanic interaction, making it a strong structure capable of bearing rutting
Influence of Thermoplastic Polyurethane on the Properties of Asphalt Cement and the Elastic Behavior of Asphalt Mixtures
Get PDFThe useful life of pavements determines the design of asphalt mixtures. However, premature structural failures and low durability are one of the main problems in pavement engineering today. The action of loads produced by traffic, exposure to environmental factors and the inadequacy of conventional designs of asphalt pavements are some of the main problems associated with the durability of the pavement. The modification of asphalt binders is an alternative that has been used for some years to improve the properties of bituminous material. Among the modifying materials are elastomers, a class of polymers with elastic properties that can be heat-treated. In this study, the asphalt was modified by wet means by adding 5, 10 and 15% of Thermoplastic Polyurethane (TPU) by weight of the binder. Subsequently, standard samples were prepared with the characterized constituents and mixtures with the modified asphalt cement. Consequently, tests were carried out to obtain the optimal mixture that improves the properties of conventional pavement. The results show that the optimal TPU addition content is 5%. With this percentage, the modified binder presented a greater elastic recovery of up to 5.60% and a reduction of up to 42.6% in penetration compared to conventional asphalt. In addition, using the Marshall method, it was determined that the stability of the modified mixtures was much higher than that of standard mixtures for light, medium and heavy traffic; so, they will have a higher resistance to deformation and better fatigue behavior
Influence of Steam Curing on the Performance of High-strength Concrete Incorporating Metakaolin
Get PDFThis study aims to investigate the influence of steam curing on the performance of high-strength concrete incorporating metakaolin. An experimental study was conducted to investigate the compressive strength, chloride permeability, initial surface absorption, and water absorption, as well as thermal degradation under various steam curing scenarios. Four concrete mixtures were prepared in this study, each with different percentages of metakaolin, as partial substitution of cement weight of 0%, 5%, 10%, and 15%. The water–binder ratio was set to 0.32 in all mixtures. The specimens underwent steam curing for 0, 4, 8, and 16 hours at a temperature of 55 °C. Results indicate that the specimens that have been steam cured and contained metakaolin exhibit improved compressive strength during the initial stages of their strength development. Steam curing has been demonstrated to enhance the concrete’s resistance to chloride penetration and reduce initial surface absorption while increasing water absorption. The optimal replacement of cement with metakaolin to enhance strength and transport properties in high-strength concrete under steam curing regimes is between 10% and 15%. Future research could examine the effects of long-term steam curing on the durability and performance of concrete incorporating an optimal proportion of metakaolin
3D Printed Concrete: Fresh and Hardened Properties
Get PDF3D concrete printing (3D CP) is an advanced form of additive manufacturing (AM), that allows for the creation of complex geometrical structures using concrete. This technology has the potential to reduce construction time and labour costs while minimizing material waste. However, there are also challenges related to material properties, structural integrity, and standardization of construction practices. The primary challenge in developing 3D printable cementitious materials lies in engineering specific fresh properties that enable extrusion-based printing. Unlike cast concrete, where formwork provides dimensional stability during the printing process, the absence of formwork in 3D printing necessitates fresh mixtures with low-slump and high-thixotropy to be suitable for concrete 3D printing. Additionally, the orthotropic nature of the resulting 3D printed object due to the extrusion process impacts its mechanical properties. Therefore, this research aims to study the effect of water content and loading directions on 3D printed concrete. A pre-mix material from Sika was used in this study. Three mixes were prepared by using three different water to dry material (w/d) ratios, 0.140 l/kg, 0.145 l/kg and 0.150 l/kg. The experiments focused on analysing flowability, green strength, mechanical properties (compressive strength, flexural strength, and modulus of elasticity), water absorption, porosity, and chemical transformations at high temperatures through thermoanalytical measurement. The results showed that the mixture containing 0.145 l/kg (w/d) exhibited satisfactory 3D printability, optimal mechanical performance, lower porosities compared with mixtures 0.140 and 0.150, and same total porosity compared with cast specimen
Unlocking Resilience: Examining the Influence of Fluid Viscous Dampers on Seismic Performance of Reinforced-concrete Structures in Earthquake-prone Regions
Get PDFIn high seismicity regions like Algeria, the seismic performance of structures is of paramount importance. This study investigates the effectiveness of fluid viscous dampers (FVDs) in enhancing the seismic resilience of a 12-story (G+12) reinforced concrete structure. By utilizing Etabs and SeismoSoft softwares, a comparative analysis is conducted between two structural configurations: one with a traditional fixed base and another incorporating fluid viscous dampers. The incorporation of FVDs aims to mitigate the seismic impact by dissipating energy, thereby reducing base shear, displacement, and acceleration during seismic events. The structure's location in a high seismicity zone necessitates robust design strategies to ensure safety and structural integrity. This paper presents a comprehensive analysis of the seismic response and advanced simulation framework providing detailed results on key parameters. The findings highlight the potential of fluid viscous dampers to significantly improve the seismic performance of reinforced concrete structures, offering a promising solution for earthquake-prone areas