scholarly journals Deterioration and Protection of Concrete Elements Embedded in Contaminated Soil: A Review

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3253
Author(s):  
Ginneth Patricia Millán Ramírez ◽  
Hubert Byliński ◽  
Maciej Niedostatkiewicz
Keyword(s):  
Contaminated Soil ◽  
Concrete Structures ◽  
Coating Materials ◽  
Advantages And Disadvantages ◽  
Concrete Deterioration ◽  
Different Types ◽  
Materials Used ◽  
Concrete Elements

Coating materials are considered one of the most antique materials of human civilization; they have been used for decoration and the protection of surfaces for millennia. Concrete structures—due to their permanent exposure to different types of environments and contaminants—require the use of coatings that contribute to its preservation by reducing the corrosion of its components (steel and aggregates). This article intends to introduce the principal causes of concrete deterioration and the coating materials used to protect concrete structures, including a summary of the coating types, their advantages and disadvantages, and the latest developments and applications. Furthermore, this paper also assesses brief information about the potential challenges in the production of eco-friendly coating materials.

scholarly journals A Monte Carlo Study of the Photon Spectrum due to the Different Materials Used in the Construction of Flattening Filters of LINAC

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
J. S. Estepa Jiménez ◽  
M. Díaz Lagos ◽  
S. A. Martinez-Ovalle
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Study ◽  
Photon Spectrum ◽  
Original Material ◽  
Advantages And Disadvantages ◽  
Mcnpx Code ◽  
Different Types ◽  
Flattening Filter ◽  
Materials Used ◽  
Photon Spectra

Different types the spectrum of photons were studied; they were emitted from the flattening filter of a LINAC Varian 2100 C/D that operates at 15 MV. The simplified geometry of the LINAC head was calculated using the MCNPX code based on the studies of the materials of the flattening filter, namely, SST, W, Pb, Fe, Ta, Al, and Cu. These materials were replaced in the flattening filter to calculate the photon spectra at the output of this device to obtain the spectrum that makes an impact with the patient. The different spectra obtained were analyzed and compared to the emission from the original spectra configuration of the LINAC, which uses material W. In the study, different combinations of materials were considered in order to establish differences between the use of different materials and the original material, with the objective of establishing advantages and disadvantages from a clinical standpoint.

Serviceability Behavior of Reinforcement Concrete Beams with Polypropylene and Steel Fibers

2015 ◽  
Vol 1129 ◽  
pp. 298-303
Author(s):  
Naser Kabashi ◽  
Cene Krasniqi ◽  
Ragip Hadri ◽  
Violeta Nushi ◽  
Arton Dautaj
Keyword(s):  
Research Work ◽  
Concrete Structures ◽  
Fiber Reinforced Polymer ◽  
Limit States ◽  
Flexural Toughness ◽  
Reinforced Polymer ◽  
Service Load ◽  
Different Types ◽  
Flexural Ductility ◽  
Concrete Elements

Serviceability Limit States (SLS) may lead to the design of concrete elements internally reinforced with Fiber Reinforced Polymer (FRP).In many types of concrete structure loss the serviceability due to wide cracks, number of cracks or large deflection is not uncommon behaviour in concrete structures or concrete beams.The flexural ductility affects the serviceability deflection of RC beams once flexural cracking take place.Imprvement will be focused on the use of polypropilene fibres , which is the subject of thispaper. The performance of concrete with fibers is judged by the flexural toughness obtained by load-deflection curves. The flexural toughness of concrete is depend on different types of fibersin use.Its tougness will be reperesent in the behaviour of RC memebres at failure. Sometimes, it is difficult to use the flexural toughness to judge the behavior of concrete structures under service load. The result of cracking on concrete beam due to the applied load and the method of loading to monitor and check the performance of concrete with different types of fiber arediscussed in this paper. The reductionin the dimension of cracks and the effect of energy disipations of polypropilene fibres will be the main aim of this research work.

scholarly journals Effect of the Mechanical Load on the Carbonation of Concrete: A Review of the Underlying Mechanisms, Test Methods, and Results

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4407
Author(s):  
Zhiyuan Liu ◽  
Philip Van den Heede ◽  
Nele De Belie
Keyword(s):  
Mechanical Load ◽  
Test Methods ◽  
Load Level ◽  
Sustained Load ◽  
Load Compensation ◽  
Advantages And Disadvantages ◽  
Concrete Deterioration ◽  
Different Types ◽  
Underlying Mechanisms ◽  
Loading Devices

As one of the major causes of concrete deterioration, the carbonation of concrete has been widely investigated over recent decades. In recent years, the effect of mechanical load on carbonation has started to attract more attention. The load-induced variations in crack pattern and pore structure have a significant influence on CO2 transport which determines the carbonation rate. With different types of load, the number, orientation, and position of the induced cracks can be different, which will lead to different carbonation patterns. In this review paper, the carbonation in cracked and stress-damaged concrete is discussed first. Then, literature about the effect of sustained load during carbonation is compared in terms of load type and load level. Finally, the advantages and disadvantages of possible test methods for investigating the effect of sustained load on carbonation are discussed with respect to loading devices, load compensation, and specimen size.

Comparative Analysis Of Bending Concrete Elements Reinforced With Steel And Fiber-Glass Reinforcement

2019 ◽  
pp. 35-40
Keyword(s):  
Comparative Analysis ◽  
Concrete Structures ◽  
Steel Reinforcement ◽  
Building Structures ◽  
Metallic Composite ◽  
Advantages And Disadvantages ◽  
Metallic Reinforcement ◽  
Glass Reinforcement ◽  
Concrete Elements ◽  
Composite Reinforcement

The main advantages and disadvantages of using non-metallic composite reinforcement as a reinforcing element of bending concrete structures without pre-stressing are considered. The characteristics of composite and steel reinforcement are compared. Numerical comparative analysis of strength and deformation characteristics of bending concrete elements with plastic and steel reinforcement is performed. It is established that to ensure the strength of the normal sections of the bending elements, the consumption of non-metallic reinforcement is up to 40% higher than that of steel reinforcement. Results of calculations on deformations according to which rigidity of the bending designs reinforced with steel reinforcement is 15-20% higher, than for reinforced with non-metallic reinforcement are presented. The conclusion is substantiated that the use of non-metallic composite reinforcement in non-stressed bendable concrete structures is impractical. Recommendations on the possible use of plastic reinforcement in building structures are presented, as well as directions and prospects for further research are outlined.

scholarly journals MODERN APPROACHES TO RESIDUAL LIFE CALCULATION OF FLEXURAL STEEL CONCRETE ELEMENTS WITH CORROSION DAMAGE

2019 ◽  
pp. 88-100
Author(s):  
G. A. Smolyago ◽  
N. V. Frolov
Keyword(s):  
Residual Life ◽  
Limit State ◽  
Concrete Structures ◽  
Corrosion Damage ◽  
Computational Techniques ◽  
Ultimate Limit State ◽  
Design Standards ◽  
Advantages And Disadvantages ◽  
Construction Design ◽  
Concrete Elements

The article is devoted to problems of ensuring durability of steel concrete elements of buildings. It is shown that durability depends on their residual and service life. Normalizing of the latter is generalized, not sufficiently substantiated and non-regulatory. Computational techniques to assess the construction durability are not yet available. Actual and informative is determining the residual life of steel concrete structures. It was noted that the reason for the reduction in the carrying capacity of steel concrete structures and, accordingly, the residual life is corrosion damage of concrete and reinforcement due to an aggressive environment. This paper analyzes the modern methods of calculating residual life of flexural elements with corrosion, identifies their advantages and disadvantages in building inspection. The residual life should be determined on the basis of field surveys, when the maximum corrosion damage is found in various design sections. The physical and statistical approach is the most promising and acceptable for assessing and predicting the residual life of flexural steel concrete elements. The value of the residual life is proposed to be established with regard to reliability coefficient. Considering the ever increasing cases of early loss of bearing capacity of steel concrete structures due to corrosion damage, it is advisable to include mandatory requirements in construction design standards of calculating on a new ultimate limit state.  

Studies on Chemical Methods to Expose Gate/Tunnel Oxide and Identification of Gate/Tunnel Oxide Defects in Wafer Fabrication

2002 ◽  
Author(s):  
Y. N. Hua ◽  
G. B. Ang ◽  
S. Redkar ◽  
Yogaspari ◽  
Wilma Richter
Keyword(s):  
Acetic Acid ◽  
Silicon Oxide ◽  
Wafer Fabrication ◽  
Chemical Methods ◽  
Advantages And Disadvantages ◽  
Different Types ◽  
Capacitor Structure ◽  
Oxide Defects ◽  
Buffer Oxide Etchant ◽  
Etch Time

Abstract In failure analysis of wafer fabrication, currently, three different types of chemical methods including 6:6:1 (Acetic Acid/HNO3/HF), NaOH and Choline are used in removing polysilicon (poly) layer and exposing the gate/tunnel oxide underneath. However, usage is limited due to their disadvantages. For example, 6:6:1 is a relatively fast etchant, but it is difficult to control the etch time and keep the oxide layer intact. Also, while using NaOH to remove poly and expose the silicon oxide, the solution needs to be heated. It is also difficult to etch a poly layer with a WSix or a CoSix silicide using NaOH. In this paper, we will discuss these 3 etchants in terms of their advantages and disadvantages. We will then introduce a new poly etchant, called HB91. HB91 is useful for removing poly to expose the gate/tunnel oxide for identification of related defects. HB91 is actually a mixture of two chemicals namely nitric acid (HNO3) and buffer oxide etchant (BOE) in a 9:1 ratio. The experimental results show that it is highly selective in poly removal with respect to the gate/tunnel oxide and is a suitable poly etchant especially for removing polysilicon with/without WSix and CoSix in the large capacitor structure. Application results of this poly etchant (HB91) will be presented.

scholarly journals Biopolymeric Materials Used as Nonviral Vectors: A Review

2021 ◽  
Vol 2 (1) ◽  
pp. 100-109
Author(s):  
Jailson de Araújo Santos ◽  
Daniel Barbosa Liarte ◽  
Alessandra Braga Ribeiro ◽  
Marcia dos Santos Rizzo ◽  
Marcília Pinheiro da Costa ◽  
...  
Keyword(s):  
Chemical Structure ◽  
Web Of Science ◽  
Gene Transfection ◽  
Genetic Material ◽  
Nonviral Vectors ◽  
Cationic Polymers ◽  
Genetic Trait ◽  
Low Diversity ◽  
Different Types ◽  
Materials Used

Bacterial transformation and gene transfection can be understood as being the results of introducing specific genetic material into cells, resulting in gene expression, and adding a new genetic trait to the host cell. Many studies have been carried out to investigate different types of lipids and cationic polymers as promising nonviral vectors for DNA transfer. The present study aimed to carry out a systematic review on the use of biopolymeric materials as nonviral vectors. The methodology was carried out based on searches of scientific articles and applications for patents published or deposited from 2006 to 2020 in different databases for patents (EPO, USPTO, and INPI) and articles (Scopus, Web of Science, and Scielo). The results showed that there are some deposits of patents regarding the use of chitosan as a gene carrier. The 16 analyzed articles allowed us to infer that the use of biopolymers as nonviral vectors is limited due to the low diversity of biopolymers used for these purposes. It was also observed that the use of different materials as nonviral vectors is based on chemical structure modifications of the material, mainly by the addition of cationic groups. Thus, the use of biopolymers as nonviral vectors is still limited to only a few polysaccharide types, emphasizing the need for further studies involving the use of different biopolymers in processes of gene transfer.

scholarly journals Assessment of dissolution profile of Pantoprazole tablets available in Bangladesh

2012 ◽  
Vol 4 (2) ◽  
pp. 58-62
Author(s):  
Aparajita Malakar ◽  
Bishwajit Bokshi ◽  
Utpal Kumar Karmakar
Keyword(s):  
Dissolution Rate ◽  
Solid Dispersion ◽  
Water Soluble ◽  
Dissolution Profile ◽  
Coating Materials ◽  
Volatile Solvents ◽  
Kneading Method ◽  
Enhanced Solubility ◽  
Materials Used ◽  
Liquisolid Compacts

The aim of the present study was to increase the solubility of a poorly water soluble BCS class II drug, valsartan. Liquisolid technology and solid dispersion by kneading method were techniques used to improve the solubility of the drug by using non-volatile solvents and some hydrophilic carriers. Liquisolid compacts were prepared by dissolving the drug in suitable non volatile solvents. The various non volatile solvents used were PG, PEG, and glycerine. The carrier coating materials play an important role in improving the solubility of the drug. The dissolution rate of the drug was increased by using propylene glycol as non-volatile solvent at 20:1 ratio of carrier to coating material. Solid dispersion by kneading method were another attempt to improve solubility the various carrier materials used were PVP K 30, PEG 6000 and mannitol, these carriers are used in various ratios to improve its solubility. The dissolution rate of drug using solid dispersion kneading method with mannitol was increased at 1:3 ratio. The DSC and FTIR studies revealed no drug excipients interactions, whereas XRD revealed the reduced crystalinity of drug, which showed enhanced solubility. From the results it was concluded that the liquisolid compacts enhanced the solubility of valsartan in comparison to traditional solid dispersion method.DOI: http://dx.doi.org/10.3329/sjps.v4i2.10441  S. J. Pharm. Sci. 4(2) 2011: 58-62

Lexical-Grammatical Status and Lexicographic Presentation of Two-Component Stable Prepositional Combinations

2021 ◽  
pp. 32-51
Author(s):  
Elena V. Generalova ◽  
Keyword(s):  
Summary Table ◽  
Complex Issue ◽  
Dictionary Entry ◽  
Figurative Meaning ◽  
Advantages And Disadvantages ◽  
Unresolved Question ◽  
Two Component ◽  
Different Types ◽  
Syntactic Properties ◽  
Theoretical Issues

The aim of the article is to review the ways of dictionary presentation of stable prepositional combinations and the factors essential for their lexical-grammatical status and the type of optimal lexicographic description. The object of the study is twocomponent prepositional combinations with stable meanings and the “preposition+noun” structure. The material of the article is data of different dictionaries of Russian presenting stable prepositional combinations. In the course of the study, the following questions were answered: why the definition and interpretation of the lexical-grammatical nature of stable prepositional combinations are so difficult and ambiguous; what lexicographic interpretation these units have in dictionaries of different types; what the advantages and disadvantages of different ways of dictionary interpretation of such language material are. The following methods were used: introspective (observation, generalization, classification), systematic lexicographic description according to dictionary parameters, dictionary definition analysis. The summary table of the lexicographic presentation of stable combinations allows seeing both the unresolved question of dictionary interpretation of such units and the patterns of their interpretation depending on the type of a dictionary. As a result of the analysis the following conclusions were drawn. 1) In modern Russian there is a rather large (about 2,000 units) class of language units (prepositional combinations), the lexical-grammatical status of which is not defined, and there is no term for their definition; this class is historically formed and continues to replenish. 2) The type of dictionary presentation of stable prepositional combinations is determined by the dictionary concept, grammatical and syntactic properties, presence of figurative meaning and possibility of component variation of such combinations. 3) The unresolved theoretical issues have as a result the lexicographic discrepancy in the presentation of these language units. Extreme lexicographic solutions are a separate dictionary entry for each combination and the presentation of such units only as stable combinations in the entry of a noun (presented in academic explanatory dictionaries). 4) Taking into account only the factor of presence/absence of a gap seems to formalize the dictionary presentation of adverbs with both conjoined and split spelling, really existing in Russian, and the position of recognition of these units with independent words and their isolate presentation is not impeccable for dictionary users. 5) In the author’s opinion, the presentation of stable prepositional combinations exclusively as independent vocabules is inferior to the traditional lexicographic approach because the isolated presentation of this material breaks the semantic connections of these complex lexical units; the most complex issue is the differentiation of adverbs with split spelling and stable combinations.

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