Shear-Strengthening of Reinforced & Prestressed Concrete Beams Using FRP

Moustapha Ibrahim Ary,Thomas H.-K. Kang 한국콘크리트학회 2012 International Journal of Concrete Structures and M Vol.6 No.1

Fiber-Reinforced Polymers (FRP) are used to enhance the behavior of structural components in either shear or flexure. The research conducted in this paper was mainly focused on the shear-strengthening of reinforced and prestressed concrete beams using FRP. The main objective of the research was to identify the parameters affecting the shear capacity provided by FRP and evaluate the accuracy of analytical models. A review of prior experimental data showed that the available analytical models used to estimate the added shear capacity of FRP struggle to provide a unified design equation that can predict accurately the shear contribution of externally applied FRP. In this study, the ACI 440.2R-08¹ model and the model developed by Triantafillou and Antonopoulos² were compared with the prior experimental data. Both analytical models failed to provide a satisfactory prediction of the FRP shear capacity. This study provides insights into potential reasons for the unsatisfactory prediction.

Genetic polymorphism of merozoite surface protein 1 and antifolate-resistant genes in Plasmodium falciparum from Mali and Niger

Mahaman Moustapha Lamine,Rabia Maman,Abdoul Aziz Maiga,Ibrahim Maman Laminou 대한기생충학ㆍ열대의학회 2023 The Korean Journal of Parasitology Vol.61 No.4

Since 2015, countries in the Sahel region have implemented large-scale seasonal malaria chemoprevention (SMC). However, the mass use of sulfadoxine-pyrimethamine (SP) plus amodiaquine impacts the genetic diversity of malaria parasites and their sensitivity to antimalarials. This study aimed to describe and compare the genetic diversity and SP resistance of Plasmodium falciparum strains in Mali and Niger. We collected 400 blood samples in Mali and Niger from children aged 3–59 months suspected of malaria. Of them, 201 tested positive (Niger, 111, 55.2%; Mali, 90, 44.8%). Polymorphism of merozoite surface protein 1 (msp1) genetic marker showed 201 allotypes. The frequency of the RO33 allotype was significantly higher in Niger (63.6%) than in Mali (39.3%). There was no significant difference in the frequency of the K1 and MAD20 allotypes between the 2 countries. The multiplicity of infection was 2 allotypes per patient in Mali and one allotype per patient in Niger. The prevalence of strains with the triple mutants Pfdhfr51I/Pfdhfr59R/Pfdhps436A/F/H and Pfdhfr51I/Pfdhfr59R/Pfdhps437G was 18.1% and 30.2%, respectively, and 7.7% carried the quadruple mutant Pfdhfr51I/Pfdhfr59R/Pfdhps436A/F/H/Pfdhps437G. Despite the significant genetic diversity of parasite populations, the level of SP resistance was comparable between Mali and Niger. The frequency of mutations conferring resistance to SP still allows its effective use in intermittent preventive treatment in pregnant women and in SMC.

Studies of the Stability of Microcrystaline Silicon Bottom-Gate TFTs under Electrical Stress

Oumkelthoum Moustapha,Alexey Abramov,Y. Bonnassieux,P. Roca i Cabarroca,H. Y. Choe 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.54 No.1

We present, in this paper, the stability results under bias stres of n-type microcrystaline silicon (μc-Si:H) botom- gate thin-film transistors (TFTs) with various intrinsic layer compositions (a single μc-Si layer or a dual intrinsic layer made of a-Si:H and μc-Si). TFTs were fabricated using the conventional amorphous silicon (a-Si:H) TFT proces(low temperature Plasma Enhanced Chemical Vapor Deposition). Our results suggest that the dual layer structure is advantageous in terms of procesing while keping good mobility and stability. After 24 hr of electrical stres the threshold voltage drift (ΔV<SUB>T</SUB>) was les than 0.2 V and mobility drift (Δμ) was about 8 %. In order to understand the causes of the instability, experimental analyses were performed; they showed that charge trapping at the interface was responsible for the degradation in the TFTs. Simulation of the impact of threshold voltage (V<SUB>T</SUB>) and the mobility drifts showed that a 1-V variation in V<SUB>T</SUB> induced a variation of 36 % in OLED curent and that a variation of 20 % in the mobility leads to a 23 % variation in the OLED curent.

Shear-Strengthening of Reinforced & Prestressed Concrete Beams Using FRP: Part I - Review of Previous Research

Ary, Moustapha Ibrahim,Kang, Thomas H.K. Korea Concrete Institute 2012 International Journal of Concrete Structures and M Vol.6 No.1

Fiber-Reinforced Polymers (FRP) are used to enhance the behavior of structural components in either shear or flexure. The research conducted in this paper was mainly focused on the shear-strengthening of reinforced and prestressed concrete beams using FRP. The main objective of the research was to identify the parameters affecting the shear capacity provided by FRP and evaluate the accuracy of analytical models. A review of prior experimental data showed that the available analytical models used to estimate the added shear capacity of FRP struggle to provide a unified design equation that can predict accurately the shear contribution of externally applied FRP. In this study, the ACI 440.2R-$08^1$ model and the model developed by Triantafillou and Antonopoulos$^2$ were compared with the prior experimental data. Both analytical models failed to provide a satisfactory prediction of the FRP shear capacity. This study provides insights into potential reasons for the unsatisfactory prediction.

DYNAMIC MR IMAGING, BIODISTRIBUTION AND PHARMACOKINETICS OF POLYMER SHELLED MICROBUBBLES CONTAINING SPION

ÅSA BARREFELT,MOUSTAPHA HASSAN,HEBA ASEM,PETER ASPELIN,TORKEL B. BRISMAR,GAIO PARADOSSI,SILVIA MARGHERITELLI,MARYAM SAGHAFIAN,LETIZIA ODDO,MAMOUN MUHAMMED 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2014 NANO Vol.9 No.6

Magnetic Resonance Imaging (MRI) is a noninvasive diagnostic method that provides informa-tion on morphological and physiological changes of the internal organs over time. Imaging andmeasurements can be repeated on the same subject, thereby reducing inter-individual variabilitye®ects and hence the number of subjects required. A potential MRI contrast agent consisting ofmicrobubbles embedded with superparamagnetic iron oxide nanoparticles (SPION) in the shell(SPION MBs) was injected intravenously into rats to determine their biodistribution andpharmacokinetics using MR imaging. Agarose phantoms containing SPION MBs were scannedusing 3 T MRI to construct a standard curve. Rats were injected with SPION MBs, free SPIONor plain MBs and scanned dynamically at 3 T using a clinical MR scanner. The relaxation rate(R2*) was studied over time as a measure of the iron oxide concentrations to enable calculation ofthe pharmacokinetic parameters. The kinetics of SPION MBs in the liver was ¯tted to a one-compartment model. Furthermore, the biological fate of SPION MBs was examined via a his-tological survey of tissue samples using Perls' Prussian blue staining and immunohistochemistry(IHC). 1.2 h after injection of SPION MBs, T2* of the liver had decreased to its minimum. Theelimination half-life of SPION MBs was 598 : 2 ? 97 : 3 h, while the half-life for SPION was222 : 6 ? 26 : 4 h. Moreover, our study showed that SPION MBs were taken up by the macrophagesin the lungs, spleen and liver. MBs labeled with SPION can be used for MR imaging. Moreover,MRI is a reliable and noninvasive tool that can be utilized in pharmacokinetic investigations offuture contrast agents using SPION MBs and SPION in the rat.

Nutraceutical Potential of New Alfalfa (Medicago sativa) Ingredients for Beverage Preparations

Maria Guadalupe Soto-Zarazua,Moustapha Bah,Anabela Silvia Gomes Costa,Francisca Rodrigues,Filipa Botelho Pimentel,Isela Rojas-Molina,Alejandra Rojas,Maria Beatriz Prior Pinto Oliveira 한국식품영양과학회 2017 Journal of medicinal food Vol.20 No.10

Alfalfa (Medicago sativa) has been extensively used as animal feed, due to its fiber, protein, minerals, and vitamins, being also a useful source of phenolic compounds with potential therapeutic benefits. Nevertheless, its potential use as human ingredient is scarce. The aim of this work was to assess the nutritional composition, amino acid profile, and antioxidant capacity (AOC) of freeze-dried juice (FDJ) and fibrous residual material (RM), two new alfalfa-derived products (Adps) recently launched as ingredients for beverage preparations. Results demonstrated a high content of proteins (23–30 g/100 g FDJ and 13–17 g/100 g RM), crude fiber (29 g/100 g RM), and minerals (such as sodium, calcium, iron, and zinc). No significant difference was found in caloric content (4 kcal/g). Essential and nonessential amino acids were quantified in both Adps being leucine and lysine the most abundant. Total phenolic and total flavonoid contents (TPC and TFC, respectively) and their changes along the different harvesting periods of the year were also examined. FDJ presented the highest TPC in May (19 mg gallic acid equivalents/g dry weight [dw]), while in October TFC had the maximum value (4 mg catechin equivalents/g dw). Both products exhibited an interesting AOC by 1,1-diphenyl-2-picrylhydrazyl (DPPH) and ferric reducing antioxidant power assays. This study reports the nutraceutical potential of two new types of Adps.

Linear rank-width of distance-hereditary graphs II. Vertex-minor obstructions

Kanté,, Mamadou Moustapha,Kwon, O-joung Academic Press 2018 European journal of combinatorics Vol.74 No.-

<P><B>Abstract</B></P> <P>In the companion paper (Adler et al., 2017), we presented a characterization of the linear rank-width of distance-hereditary graphs, from which we derived an algorithm to compute it in polynomial time. In this paper, we investigate structural properties of distance-hereditary graphs based on this characterization.</P> <P>First, we prove that for a fixed tree T , every distance-hereditary graph of sufficiently large linear rank-width contains a vertex-minor isomorphic to T . We extend this property to bigger graph classes, namely, classes of graphs whose prime induced subgraphs have bounded linear rank-width. Here, prime graphs are graphs containing no splits. We conjecture that for every tree T , every graph of sufficiently large linear rank-width contains a vertex-minor isomorphic to T . Our result implies that it is sufficient to prove this conjecture for prime graphs.</P> <P>For a class Φ of graphs closed under taking vertex-minors, a graph G is called a <I>vertex-minor obstruction</I> for Φ if G ∉ Φ but all of its proper vertex-minors are contained in Φ . Secondly, we provide, for each k ⩾ 2 , a set of distance-hereditary graphs that contains all distance-hereditary vertex-minor obstructions for graphs of linear rank-width at most k . Also, we give a simpler way to obtain the known vertex-minor obstructions for graphs of linear rank-width at most 1.</P>

Shear-Strengthening of Reinforced & Prestressed Concrete Beams Using FRP

Thomas H.-K. Kang,Moustapha Ibrahim Ary 한국콘크리트학회 2012 International Journal of Concrete Structures and M Vol.6 No.1

The main objectives of this research were to experimentally evaluate the impact of Carbon Fiber-Reinforced Polymers (CFRP) amount and strip spacing on the shear behavior of prestressed concrete (PC) beams and to evaluate the applicability of existing analytical models of Fiber-Reinforced Polymer (FRP) shear capacity to PC beams shear-strengthened with CFRP. The Ushaped CFRP strips with different spacing were applied externally to the test specimens in order to observe the overall behavior of the prestressed concrete I-beams and the mode of failure of the applied CFRP strips. Results obtained from the experimental program showed that the application of CFRP strips to prestressed concrete I-beams did in fact enhance the overall behavior of the specimens. The strengthened specimens responded with an increase in ductility and in shear capacity. However, it should be noted that the CFRP strips were not effective at all at spacing greater than half the effective depth of the specimen and that fracture of the strips was the dominant failure mechanism of CFRP. Further research is needed to confirm the conclusion derived from the experimental program.

Assessment of Beneficial and Possible Toxic Effects of Two New Alfalfa-Derived Shelf Products

Maria G. Soto-Zarazua,Moustapha Bah,Maria G. Garcia-Alcocer,Laura C. Berumen,Carla Sofia Costa,Maria Joao Bessa,Francisca Rodrigues,Joao Paulo Teixeira,Maria Beatriz P.P. Oliveira 한국식품영양과학회 2016 Journal of medicinal food Vol.19 No.10

Aerial parts of Medicago sativa L. have been used as food and its consumption has been associated with health benefits, one among the most important being menopausal symptoms control. This work was aimed to explore possible pharmacological effects of two new alfalfa-derived products that have recently emerged as daily beverage preparations. In exploring their potential estrogenic effects, they produced no relevant alteration in the uterus. However, lowering glucose levels until normal values without causing further hypoglycemic effect were observed, when rats were treated with 1.5 g/kg/day samples. In vivo acute toxicity was not found when the alfalfa products were tested up to 3 g/kg rat weight. Furthermore, in vitro studies were conducted to assess their possible toxic effects. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and lactate dehydrogenase tests were carried out on the Caco-2 cell model to determine cell viability and membrane integrity. A concentration-dependent effect was observed, with a significant decrease in cell viability after exposure to concentrations of alfalfa product up to 100 mg/mL (after 3 h of incubation) and 50 mg/mL (after 24 h of treatment). Although in vitro level, the decrease in cell viability at these still low doses may underlie some toxicity, making necessary additional studies before any recommendation of a sustained consumption of these products by humans.

Shear-Strengthening of Reinforced & Prestressed Concrete Beams Using FRP: Part II - Experimental Investigation

Kang, Thomas H.K.,Ary, Moustapha Ibrahim Korea Concrete Institute 2012 International Journal of Concrete Structures and M Vol.6 No.1

The main objectives of this research were to experimentally evaluate the impact of Carbon Fiber-Reinforced Polymers (CFRP) amount and strip spacing on the shear behavior of prestressed concrete (PC) beams and to evaluate the applicability of existing analytical models of Fiber-Reinforced Polymer (FRP) shear capacity to PC beams shear-strengthened with CFRP. The Ushaped CFRP strips with different spacing were applied externally to the test specimens in order to observe the overall behavior of the prestressed concrete I-beams and the mode of failure of the applied CFRP strips. Results obtained from the experimental program showed that the application of CFRP strips to prestressed concrete I-beams did in fact enhance the overall behavior of the specimens. The strengthened specimens responded with an increase in ductility and in shear capacity. However, it should be noted that the CFRP strips were not effective at all at spacing greater than half the effective depth of the specimen and that fracture of the strips was the dominant failure mechanism of CFRP. Further research is needed to confirm the conclusion derived from the experimental program.