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Analytical, experimental and numerical study of timber-concrete composite beams for bridges

  • Molina, Julio C.;Calil, Carlito Junior;de Oliveira, Diego R.;Gomes, Nadia B.
    • Computers and Concrete
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    • v.24 no.2
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    • pp.103-115
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    • 2019
  • In this study, the strength and stiffness (EI) of wood-concrete composite beams for bridges with T-shaped cross section were evaluated. Two types of connectors were used: connectors bonded with epoxy adhesive and connectors attached to the wood just by pre-drilling (without adhesive). The connectors consisted of common steel bars with a diameter of 12.5 mm. Initially, the strength and stiffness (EI) of the beams were analyzed by bending tests with the load applied at the third point of the beam. Subsequently, the composite beams were evaluated by numerical simulation using ANSYS software with focus on the connection system. To make the composite beams, Eucalyptus citriodora wood and medium strength concrete were used. The slip modulus K and the ultimate strength values of each type of connector were obtained by direct shear tests performed on composite specimens. The results showed that the connector glued with epoxy adhesive resulted in better strength and stiffness (EI) for the composite beams when compared to the connector fixed by pre-drilling. The differences observed were up to 10%. The strength and stiffness (EI) values obtained analytically by $M{\ddot{o}}hler^{\prime}$ model were lower than the values obtained experimentally from the bending tests, and the differences were up to 25%. The numerical simulations allowed, with reasonable approximation, the evaluation of stress distributions in the composite beams tested experimentally.

Trueness of 3D printed partial denture frameworks: build orientations and support structure density parameters

  • Hussein, Mostafa Omran;Hussein, Lamis Ahmed
    • The Journal of Advanced Prosthodontics
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    • v.14 no.3
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    • pp.150-161
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    • 2022
  • PURPOSE. The purpose of the study was to assess the influence of build orientations and density of support structures on the trueness of the 3D printed removable partial denture (RPD) frameworks. MATERIALS AND METHODS. A maxillary Kennedy class III and mandibular class I casts were 3D scanned and used to design and produce two 3D virtual models of RPD frameworks. Using digital light processing (DLP) 3D printing, 47 RPD frameworks were fabricated at 3 different build orientations (100, 135 and 150-degree angles) and 2 support structure densities. All frameworks were scanned and 3D compared to the original virtual RPD models by metrology software to check 3D deviations quantitatively and qualitatively. The accuracy data were statistically analyzed using one-way ANOVA for build orientation comparison and independent sample t-test for structure density comparison at (α = .05). Points study analysis targeting RPD components and representative color maps were also studied. RESULTS. The build orientation of 135-degree angle of the maxillary frameworks showed the lowest deviation at the clasp arms of tooth 26 of the 135-degree angle group. The mandibular frameworks with 150-degree angle build orientation showed the least deviation at the rest on tooth 44 and the arm of the I-bar clasp of tooth 45. No significant difference was seen between different support structure densities. CONCLUSION. Build orientation had an influence on the accuracy of the frameworks, especially at a 135-degree angle of maxillary design and 150-degree of mandibular design. The difference in the support's density structure revealed no considerable effect on the accuracy.

Sensitivity and uncertainty quantification of neutronic integral data in the TRIGA Mark II research reactor

  • Makhloul, M.;Boukhal, H.;Chakir, E.;El Bardouni, T.;Lahdour, M.;Kaddour, M.;Ahmed, Abdulaziz;Arectout, A.;El Yaakoubi, H.
    • Nuclear Engineering and Technology
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    • v.54 no.2
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    • pp.523-531
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    • 2022
  • In order to study the sensitivity and the uncertainty of the Moroccan research reactor TRIGA Mark II, a model of this reactor has been developed in our ERSN laboratory for use with the N-Particle MCNP Monte Carlo transport codes (version 6). In this article, the sensitivities of the effective multiplication factor of this reactor are evaluated using the ENDF/B-VII.0, ENDF/B-VII.1 and JENDL-4.0 libraries and in 44 energy groups, for the cross sections of the fuel (U-235 and U-238) and the moderator (H-1 and O-16). However, the quantification of the uncertainty of the nuclear data is performed using the nuclear code NJOY99 for the generation and processing of covariance matrices. On the one hand, the highest uncertainty deviations, calculated using the ENDFB-VII.1 and JENDL4.0 evaluations, are 2275, 386 and 330 pcm respectively for the reactions U235(n, f), $ U_{235}(n\bar{\nu})$ and H1(n, γ). On the other hand, these differences are very small for the neutron reactions of O-16 and U-238. Regarding the neutron spectra, in CT-mid plane, they are very close for the three evaluations (ENDF/B-VII.0, ENDF/B-VII.1 and JENDL-4.0). These spectra present two peaks (thermal and fission) around the energies 0.05 eV and 1 MeV.

Influence of inorganic composition and filler particle morphology on the mechanical properties of self-adhesive resin cements

  • Marina Rodrigues Santi ;Rodrigo Barros Esteves Lins;Beatriz Ometto Sahadi;Giovanna Correa Denucci;Gabriela Soffner ;Luis Roberto Marcondes Martins
    • Restorative Dentistry and Endodontics
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    • v.47 no.3
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    • pp.32.1-32.11
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    • 2022
  • Objectives: This study aimed to evaluate the influence of inorganic composition and filler particle morphology on the mechanical properties of different self-adhesive resin cements (SARCs). Materials and Methods: Three SARCs including RelyX Unicem-2 (RUN), Maxcem Elite (MAX), and Calibra Universal (CAL) were tested. Rectangular bar-shaped specimens were prepared for flexural strength (FS) and flexural modulus (FM) and determined by a 3-point bending test. The Knoop microhardness (KHN) and top/bottom microhardness ratio (%KHN) were conducted on the top and bottom faces of disc-shaped samples. Sorption (Wsp) and solubility (Wsl) were evaluated after 24 hours of water immersion. Filler morphology was analyzed by scanning electron microscopy and X-ray energy dispersive spectroscopy (EDS). FS, FM, %KHN, Wsp, Wsl, and EDS results were submitted to 1-way analysis of variance and Tukey's post-hoc test, and KHN also to paired t-test (α = 0.05). Results: SARC-CAL presented the highest FS value, and SARC-RUN presented the highest FM. SARC-MAX and RUN showed the lowest Wsp and Wsl values. KHN values decreased from top to bottom and the SARCs did not differ statistically. Also, all resin cements presented carbon, aluminum, and silica in their composition. SARC-MAX and RUN showed irregular and splintered particles while CAL presented small and regular size particles. Conclusions: A higher mechanical strength can be achieved by a reduced spread in grit size and the filler morphology can influence the KHN, as well as photoinitiators in the composition. Wsp and Wsl can be correlated with ions diffusion of inorganic particles.

Effects on Mechanical Properties, Joint Range of Motion, and Grip Strength of Forearm Muscles Depending on Wrapping Direction of the Floss Band

  • Ki Bum Jung;Seohui Kim;Yongwoo Lee
    • Physical Therapy Rehabilitation Science
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    • v.13 no.1
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    • pp.95-105
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    • 2024
  • Objective: The purpose was to investigate changes in mechanical properties, range of motion, and grip strength of the forearm muscle in 13 students depending on the wrapping direction of the floss band. Design: A single-blind, crossover study Methods: Subjects were randomly assigned to the wrapping direction of the flossing band and then performed a concentric exercise of the wrist flexors using a Flex-Bar. Intervention A applied the flossing band in a right spiral direction, Intervention B applied the flossing band in a left spiral direction, and Intervention C performed the exercise alone. All subjects used their dominant right hand, and pre- and post-assessments were conducted between interventions. To analyze differences in changes between groups pre- and post-, all results were subjected to one-way ANOVA, followed by Scheffe's test as a post-hoc analysis. The paired samples t-test was used to analyze the difference between pre- and post-change within groups. Results: First, in the mechanical properties of the Flexor carpi ulnaris (FCU) muscle, interventions A and B significantly improved muscle tone and stiffness than intervention C (p<0.05), and intervention A showed a significant decrease in decrement (muscle elasticity) than intervention B (p<0.05). Second, interventions A and B showed significant improvement in grip strength than intervention C (p<0.05). Conclusions: The right spiral direction of the flossing band tended to increase the elasticity of the muscles compared to the left spiral direction. Therefore, in future studies, it is necessary to choose the direction of the flossing band to increase the elasticity of the muscles.

Quantitative Expression Analysis of Functional Genes in Four Dog Breeds (개의 네 품종에서 기능 유전자들에 대한 정량적 발현 분석)

  • Gim, Jeong-An;Kim, Sang-Hoon;Lee, Hee-Eun;Jeong, Hoim;Nam, Gyu-Hwi;Kim, Min Kyu;Huh, Jae-Won;Choi, Bong-Hwan;Kim, Heui-Soo
    • Journal of Life Science
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    • v.25 no.8
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    • pp.861-869
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    • 2015
  • One of the domesticated species; the dog has been selectively bred for various aims by human. The dog has many breeds, which are artificially selected for specific behaviors and morphologies. Dogs contribute their life to human as working dogs for guide, rescue, detection or etc. Working dogs requires good personality, such as gentleness, robustness and patience for performing their special duty. Many studies have concentrated on finding genetic marker for selecting the high-quality working dog. In this study, we confirmed quantitative expression patterns of eight genes (ABAT; 4-Aminobutyrate Aminotransferase, PLCB1; Phospholipase C, Beta 1, SLC10A4; Solute Carrier Family 10, Member 4, WNT1; Wingless-Type MMTV Integration Site Family, Member 1, BARX2; BarH-Like Homeobox 2, NEUROD6; Neuronal Differentiation 6, SEPT9; Septin 9 and TBR1; T-Box, Brain, 1) among brains tissues from four dog breeds (Beagle, Sapsaree, Shepherd and Jindo), because these genes were expressed and have functions in brain mostly. Specially, BARX2, SEPT9, SLC10A4, TBR1 and WNT1 genes were highly expressed in Beagle and Jindo, and Sapsaree and German Shepherd were vice versa. The biological significance of total genes was estimated by database for annotation, visualization and integrated discovery (DAVID) to determine a different gene ontology (GO) class. In these analyses, we suppose to these eight genes could provide influential information for brain development, and intelligence of organisms. Taken together, these results could provide clues to discover biomarker related to functional traits in brain, and beneficial for selecting superior working dogs.

An Experimental study on the behavior of gap N-joints in Cold-formed Square Hollow Sections with connection plate for a tension member (인장용 연결 플레이트를 갖는 각형강관 갭 N형 접합부의 거동에 관한 실험적 연구)

  • Park, Keum Sung;Bae, Kyu Woong;Moon, Tae Sup
    • Journal of Korean Society of Steel Construction
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    • v.16 no.6 s.73
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    • pp.769-780
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    • 2004
  • This paper's objective is to evaluate the experimental behavior of gap N-joints made of cold-formed, square, hollow steel sections, with a connection plate as a tension member. The principal parameters for testing included the ratio of chord width to thickness, the ratio of brace width to chord width, eccentric ratio, the shape of the compression member, the branch angle, and the stiffening plate of the chord flange. The strength and failure mode were examined through the test for the gap N-joint, consisting of several parameters. Based on the results of the test, the gap N-joints were determined according to the capacity preceding the displacement of the tension, regardless of the width ratio, and the split failure mode-connected surface for a chord in joints. The strength of the gap N-joints increased proportionally as the $2\gamma$(B/T) ratio decreased, and as the width ratio(${\beta}$) of branch to chord increased. Particularly, $2\gamma$(B/T) decreased as the capacity of gap N-joint increased. The results of the test were summarized for the capacity, initial stiffness, ductility, and change of the failure mode of each gap N-joint.

Awareness and performance about nosocomial infection management; a early stage nurse in small and medium hospitals (병원감염관리에 관한 인지도와 수행도 - 중소병원 초보간호사를 중심으로 -)

  • Kim, Jung-Mi;Choi, Young-Sil
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.8
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    • pp.492-500
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    • 2018
  • This study was conducted to identify the degrees of awareness and performance of hospital infection control of early stage nurses working in medium and small sized hospitals. This survey was conducted for 15 days from Sep. 15 to Sep. 30, 2017. Data were then analyzed by SPSS Win 22.0 to determine the mean and SD, as well as to conduct t-tests, ANOVA, and Scheffe's test. The result were as follows: 1. There were significant differences in awareness of hospital infection according to urinary tract infection, respiratory infection, and disinfection of contaminated goods managements with age. 2. There were significant differences in performance of hospital infection according to hand washing (working department), fluid therapy (education need p<0.001), urinary tract (position), and respiratory infection management (position p<0.001). 3. The mean score of awareness and performance regarding hospital infection were significantly different (all items p<0.001). According to these results, systematic education for improving awareness and performance regarding hospital infection control by nursing staff in medium and small sized in hospitals should be conducted. In addition, organizational efforts to increase the number of early stage nurses and improve the usability of personal infection control devices should be encouraged.

Experimental Evaluation on Effective Moment of Inertia of Reinforced Concrete Simple Beams and Continuos Beams Considering Tension Stiffening Effect (인장증강효과를 고려한 철근콘크리트 단순보와 연속보의 유효 단면2차모멘트에 대한 실험적 검증)

  • Lee, Seung-Bae;Yoon, Hyeong-Jae;Kim, Kang-Su;Kim, Sang-Sik
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.11a
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    • pp.285-288
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    • 2008
  • A model for the effective moment of inertia $I_{\epsilon}$ as expressed in Branson's equation, in which reduction of the flexural rigidity of RC beams due to cracking are aptly taken into accoun,t is presented. However, KCI Code isn`t considered tension stiffening as it is in debonding of reinforcing bar. Therefore, this equation need to set up suitable to our design Code. The experimental work consisted of casting and testing a total of 6 simply supported reinforced concrete beams and a total of 4 continuos reinforced concrete beams under two point concentrated loads. Main parameters are concrete strength, coverage, bond between concrete and reinforcing bars, are known as have an effect on deflection and tension stiffening. Every test beams had the same $250{\times}350$mm rectangular section, with a simply supported clear span of 4,400 mm and a continuos clear span of 6,500 mm. Comparison of the test results with values obtained using the KCI Code equation of the effective moment of inertia showed a noticeable difference.

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Stable expression of brazzein protein, a new type of alternative sweetener in transgenic rice (형질전환 벼에서 brazzein 감미단백질의 안정적인 발현)

  • Lee, Ye Rim;Akter, Shahina;Lee, In Hye;Jung, Yeo Jin;Park, So Young;Cho, Yong-Gu;Kang, Kwon Kyoo;Jung, Yu Jin
    • Journal of Plant Biotechnology
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    • v.45 no.1
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    • pp.63-70
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    • 2018
  • Brazzein is the smallest sweet protein and was isolated from the fruit pulp of Pentadiplandra brazzeana Baillon, native to tropical Africa. From ancient times, the indigenous people used this fruit in their diet to add sweetness to their daily food. Brazzein is 500 to 2000 times sweeter than sucrose on a weight basis and 9500 times sweeter on a molar basis. This unique property has led to increasing interest in this protein. However, it is expensive and difficult to produce brazzein other than in its native growing conditions which limits its availability for use as a food additive. In this study, we report high production yields of, brazzein protein in transgenic rice plants. An ORF region encoding brazzein and driven by the $2{\times}CaMV\;35S$ promoter was introduced into rice genome (Oryza sativa Japonica) via Agrobacterium-mediated transformation. After transformation, 17 regenerated plant lines were obtained and these transgene-containing plants were confirmed by PCR analysis. In addition, the selected plant lines were analyzed by Taqman PCR and results showed that 9 T0 lines were found to have a single copy out of 17 transgenic plants. Moreover, high and genetically stable expression of brazzein was confirmed by western blot analysis. These results demonstrate that recombinant brazzein was efficiently expressed in transgenic rice plants, and that we have developed a new rice variety with a natural sweetener.