The hybrid steel frame is a new laterally resistant steel frame composed of rigid and semi-rigid connections. The objective of this study is to select a hybrid frame with an appropriate seismic ...performance based on a multi-criteria decision-making approach. The seismic performance of different patterns and positions of semi-rigid connections within the selected frames is examined. Static, cyclic and nonlinear dynamic analyses are conducted on the selected frames. The Analytic Hierarchy Process is then used to evaluate the performance of the frames. The results indicate that the hybrid frame can offer an enhanced performance in comparison with rigid frames if the hybrid frame is well proportioned.
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BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
•Orthotropy on the material scale and system scale influenced the mechanical behavior.•The configuration of the veneer layers strongly affected the specimen responses.•The adhesive between the veneer ...layers did not affect the mechanical behavior.
Balsa wood is an appropriate core material for structural sandwich applications due to its high strength- and stiffness-to-weight ratios. However, the mechanical properties vary considerably owing to the inherent scattering of natural wood materials. One approach to reduce this scatter and tailor the mechanical properties according to specific application needs is to recompose the natural material into a veneered material consisting of veneer layers of different grain orientations, which are adhesively bonded together. The mechanical properties of such a veneered balsa wood, composed of alternating 0°/90° grain orientations, were investigated at ambient temperature according to corresponding standards. The properties were significantly influenced by the orthotropy on the material scale within one veneer layer and on the system scale within the assembled veneer layers. Standardized experimental set-ups and specimen geometries may produce artifacts such as buckling or strain hardening which deviate from the material behavior in real structures. The thin adhesive between the veneer layers did not negatively affect the mechanical behavior since failure occurred within the veneer layers and not in the interfaces.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•The configuration of the veneer layers strongly affected the specimen responses.•All specimens lost more than 90% of their strength and stiffness up to 250 °C.•The different specimen volumes ...affected the rate of drying and thus property reduction.
The tensile, compressive and shear behavior of standardized specimens cut from a veneered balsa wood used as structural sandwich core was investigated at ambient temperatures of up to 250 °C. The average moisture content was 9.1%. The specimens’ responses were strongly affected by the configuration of the veneer layers. Specimens with a higher number of 0° veneer layers in the loading direction exhibited higher strength and stiffness at each temperature. Independent of the loading type, the specimens gradually lost strength and stiffness up to the wood-burning temperature of 250 °C due to the softening of the hemicellulose and lignin. Smaller cross sections with more surfaces cut perpendicular to the grain dried faster and thus delayed the degradation of properties. The dominant failure modes did not change with increasing temperature if the behavior remained either fiber- or matrix-dominated. The failure mode changed if the behavior shifted from fiber-dominated at lower temperatures to matrix-dominated at higher temperatures. The degradation of the properties of the adhesive between the veneer layers affected specimen behavior only at the highest temperature.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Composite sandwich panels composed of a balsa core and glass fiber-reinforced polymer (GFRP) face sheets may offer attractive applications for building slabs and bridge decks. Such composite panels ...may contain air-filled gaps (caused by initial defects or damage) or through-thickness cracks and different types of metallic inserts (used for facilities and piping systems) in the balsa core. The fire performance of sandwich panels can be reduced by the local heating effects inside such air gaps and inserts. The thermomechanical response of GFRP-balsa sandwich panels comprising through-thickness air gaps or steel inserts, subjected to combined mechanical load and one-sided ISO 834 fire, were thus investigated by fire experiments and uncoupled thermal and mechanical numerical analysis. The results demonstrated that the shear resistance reduction of the core is not critical, while the moment resistance reduction can lead to panel failure. The propagation of a transverse tensile crack in the balsa core produced a similar moment resistance reduction to an air gap or steel insert. The air gaps and steel inserts charred the inner core zones and heated the cold face sheet above, leading to face wrinkling. The effects of air gaps and steel inserts remained local. Depending on their location in a panel, they may thus not exhibit significant effects on the whole structure. If they are placed on critical load paths however, e.g. in the vicinity of supports, they may cause collapse of the whole structure. Since the extension of transverse tensile cracks is not limited, they may also lead to an overall collapse.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Sandwich systems composed of combustible glass fiber-reinforced polymer (GFRP) face sheets and balsa cores must fulfill fire resistance requirements if used, for instance, in bridge or building ...construction. Air gaps and steel inserts in the balsa core, the latter to suspend external pipes below bridge decks for example, may therefore present critical zones where heat ingress is facilitated, and fire resistance is therefore reduced. The thermal responses of such GFRP-balsa sandwich panels comprising through-thickness air gaps or steel inserts, and subjected to a one-sided external fire, were thus investigated by furnace experiments and fluid-structure interaction simulations. Through-thickness air gaps and steel inserts between the face sheets cooled the surrounding zones close to the hot face and heated those located towards the cold face. In T-shape steel inserts penetrating the bottom face sheet, the fire-exposed flange collected the heat and the whole section around the insert was significantly heated. The results revealed that the remaining cross section might be considerably reduced by char formation around the air gaps and steel inserts. Although the effect is quite local, it may be significant if slabs are unidirectional or if it occurs at critical locations, e.g., in the vicinity of supports.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Since the current treatments have not resulted in the desired outcomes for melanoma patients, there is a need to identify more effective medications. Together with other snake venom proteins, ...cytotoxin-II has shown promising results in tumoral cells. In this study, recombinant cytotoxin-II (rCTII) was expressed in SHuffle
T7 Express cells, while the epitope mapping of rCTII was performed to reveal the antibody-binding regions of rCTII. The MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was used to assess the viability of SK-MEL-3 and HFF-2 cells after treating these cells with rCTII. The qRT-PCR was performed to evaluate the expression levels of matrix metallopeptidase 3 (
),
,
, caspase-8, caspase-9, and miR-214 in order to reveal the rCTII-induced signaling pathways in melanoma. Our results have shown that two regions of amino acids, 6-16 and 19-44, as predicted epitopes of this toxin, are essential for understanding the toxicity of rCTII. Treating the melanoma cells with rCTII substantially inhibited the transforming growth factor-beta (TGF-β)-SMAD signaling pathway and down-regulated the expression of
and miR-214 as well. This cytotoxin also restored apoptosis mainly via the intrinsic pathway. The down-regulation of
and miR-214 might be associated with the anti-metastatic property of rCTII in melanoma. The inhibitory effect of rCTII on the TGF-β signaling pathway might be associated with increased apoptosis and decreased cancer cell proliferation. It is interesting to see that the IC50 value of rCTII has been lower in the melanoma cells than non-tumoral cells, which may indicate its potential effects as a drug. In conclusion, rCTII, as a novel medication, might serve as a potent and efficient anticancer drug in melanoma.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Knowledge, attitudes, and practices (KAP) studies are widely used in public health. This study aimed to investigate and compare KAP among patients with coronary artery disease (CAD) and premature ...coronary artery disease (PCAD) regarding cardiovascular disease (CVD).
This cross-sectional study was conducted on 100 PCAD patients and 100 CAD patients in a general hospital in Tehran, Iran, between April and October 2022. A valid questionnaire was utilized to gather information, and descriptive analysis and logistic regression were employed for analysis using SPSS, version 23.
This study involved 100 CAD and 100 PCAD patients with average ages of 68.09±7.20 and 50.20±7.65 years, respectively. Men accounted for 58% of the PCAD group and 73% of the CAD group. The PCAD group had a higher level of knowledge and exhibited a more positive attitude toward CVD than the CAD group (P=0.007 and P<0.001, respectively). The PCAD patients and those with a family history of chronic diseases had a higher level of knowledge (P=0.045 and P=0.27, respectively) and showed a more positive attitude (P=0.030 and P<0.001, respectively). However, participants with a self-reported history of chronic diseases and those who were employed exhibited a less positive attitude. Occupation was associated with nutritional and smoking status (P=0.037).
Higher levels of knowledge and more positive attitudes regarding CVD were observed; still, the study population's behaviors were unsatisfactory. Educational interventions are needed to promote positive health behaviors, emphasizing the link between knowledge and risk reduction and decreased CVD and mortality rates.
Non-alcoholic fatty liver disease is one of the most common chronic liver diseases. Due to the lack of definitive documentation for the effect of folic acid on fatty liver, this study was conducted ...to determine the relationship between serum folate levels and fatty liver in patients referred to Imam Hossain Hospital in Shahroud, in 2016.
This case–control study was performed on 150 patients. The case group was fatty liver patients whose disease was diagnosed based on laboratory and ultrasound findings and a control group of patients without fatty liver. After liver ultrasonography, blood samples were taken from all patients and folic acid levels were measured.
Of the 150 patients examined, mean BMI of patients was (25.3 ± 6.1 kg/m2 in case group and 24.8 ± 7.2 kg/m2 in control group), which was significantly higher in case group (p < 0.035). The mean fasting blood glucose level in patients was (137.5 ± 53.5 mg/dl in case group and 124.5 ± 62.5 mg/dl in control group), which was significantly higher in case group (p < 0.01). The mean LDL of the patients was (175.3 ± 65.5 mg/dl in case group and 125.5 ± 42.5 mg/dl in control group), which was significantly higher (P < 0.003) in patients with fatty liver. The mean of folic acid in patients was (3.7 ± 5.3 ng/ml in case group and 5.3 ± 4.1 ng/ml in control group), which was significantly lower in patients with fatty liver (p < 0.01).
The results of this study showed that folic acid deficiency was significantly higher in patients with fatty liver than in other patients. But in order to fully confirm this, more research is needed with a larger sample size.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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