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Plantation softwood timber poles are associated with low natural durability, and it is also not clear what the effects of the high humidity environment on the long-term performance of composite action integrity of such a system. This paper presents a durability study for the proposed composite poles using (GFRP) glass fiber-reinforced polymer as a confinement system on wooden poles sourced from plantation softwood timber. Radiata pine poles of 6 m length were wrapped with multiple layers of 0°/90° woven roving biaxial E-glass fiber sheets through a wet layup process as confinement. The prepared GFRP softwood poles were then subjected to high humidity environmental conditions of up to 95 ± 2% relative humidity and 22 ± 2 °C temperature for a period of 30 months. Various lengths of confinement were considered in this study ranging from 0% to 70% of the span length. The poles had a span length of 5.4 m and were tested using a three-point bending test. Results showed that the proposed confinement system of GFRP-softwood provided a satisfactory long-term performance and the high humidity environment did not greatly affect the improvement in the mechanical performance that the GFRP system provided. [ABSTRACT FROM AUTHOR]

Carbon fiber reinforced polymer (CFRP) composites have exhibited a great potential for strengthening of steel structures. In the current study, an innovative prestressed unbonded reinforcement (PUR) system is introduced for fatigue strengthening of existing steel members. The system relies on a pair of mechanical clamps; each holds multiple CFRP plates and anchors their prestressing forces to the steel substrate via friction. A finite element model was established to optimize the design of the required mechanical components of the system. A set of static and fatigue tests was conducted on the developed mechanical clamps as the key elements of the proposed PUR system. The performance of the PUR system was then evaluated using a set of fatigue tests on two precracked steel plate specimens, one without any strengthening system and the other one strengthened with the proposed PUR system. In the latter specimen, the CFRP plates were prestressed up to about 800 MPa (approximately 30% of the CFRP tensile strength), which resulted in a complete fatigue crack arrest in the precracked steel plate. Furthermore, neither slippage of the mechanical clamps nor any prestress loss in the CFRP plates was observed after 7.5 million fatigue cycles. Based on the promising experimental results, obtained from the sets of fatigue tests performed in the current study, it can be concluded that the proposed PUR system can be considered as an efficient alternative to the conventional bonded reinforcement solutions for fatigue strengthening of damaged steel members. [ABSTRACT FROM AUTHOR]

Seawater and sea sand concrete (SWSSC) is an environmentally friendly alternative to ordinary Portland cement concrete for civil construction. However, the detrimental effect of high chloride content of SWSSC on the corrosion resistance of steel reinforcement is a concern. This study undertook the electrochemical corrosion behaviour and surface characterizations of a mild steel and two stainless steels (AISI type 304 and 316) in various simulated concrete environments, including the alkaline + chloride environment (i.e., SWSSC). Open circuit potential (OCP), potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) were employed. Though chloride is detrimental to the corrosion resistance of mild steels, a simultaneous presence of high alkalinity in SWSSC negate the detrimental effect of chloride. In the case of stainless steels, a high level of alkalinity is found to be detrimental, whereas chloride seems to have less detrimental effect on their corrosion resistance. [ABSTRACT FROM AUTHOR]

This literature review has examined the use of FRP composite materials as a potential retrofitting technique for civil structures. Importantly, the various material properties, bond mechanisms, durability issues and fatigue resistance have been discussed. Studies exploring the performance of CFRP repaired steel have strongly indicated its potential as a rehabilitation material. These systems offer many improvements over the current bulky and less chemically resistant methods of bolting or welding steel plate patches. This review has established and highlighted the factors that affect CFRP/steel bond durability, namely surface preparation, curing, corrosion, fatigue loading, temperature and moisture ingress through studies that focus on their effect. These studies, however, often focus on a single influencing factor or design criteria. Only limited studies have investigated multiple parameters applied simultaneously, even though they commonly occur together in industrial practice. This review aimed to summarise the numerous influencing parameters to give a clearer understanding of the relevance of CFRP repaired steel structures. [ABSTRACT FROM AUTHOR]

Seawater and sea sand concrete (SWSSC) is a highly attractive alternative to normal concrete (NC) that requires huge amounts of fresh water and river sand. However, reinforcements of stainless steel (instead of mild steel that is used in NC) may be required for SWSSC. This article reports investigation of stress corrosion cracking (SCC) of AISI 316 stainless steel (SS) in simulated SWSSC and NC environments, with and without addition of silica to SWSSC and NC, employing slow strain rate testing (SSRT) at 25 and 60 °C. For the purpose of comparison, SCC of SS was also investigated in simulated seawater (SW) solution. SS showed no SCC at 25 °C in any of the test solutions. Indications of SCC were seen in SW at 60 °C, but no features of SCC in SWSSC and NC at 60 °C, as suggested by scanning electron microscopy (SEM) fractographs. While the absence of SCC in SWSSC and NC is attributed to the highly passivating alkaline condition, its absence in SWSSC also indicates the role of alkalinity to predominate the deleterious role of chloride content of SWSSC. However, the addition of silicate to SWSSC or NC triggers transgranular SCC to SS at 60 °C, as evidenced by the fractography. [ABSTRACT FROM AUTHOR]

The present study indicates the importance of using glass fiber reinforced polymer (GFRP) laminates with appropriate thickness and fibers orientation when exposed to harsh environmental conditions. The effect of different environmental conditions on tensile properties of different GFRP laminates is investigated. Laminates were exposed to three environmental conditions: (1) Freeze/thaw cycles without the presence of moisture, (2) freeze/thaw cycles with the presence of moisture and (3) UV radiation and water vapor condensation cycles. The effect of fiber configuration and laminate thickness were investigated by considering three types of fiber arrangement: (1) Continuous unidirectional, (2) continuous woven and (3) chopped strand mat and two thicknesses (2 and 5 mm). Microstructure and tensile properties of the laminates after exposure to different periods of conditioning (0, 750, 1250 and 2000 h) were studied using SEM and tensile tests. Statistical analyses were used to quantify the obtained results and propose prediction models. The results showed that the condition comprising UV radiation and moisture condition was the most aggressive, while dry freeze/thaw environment was the least. Furthermore, the laminates with chopped strand mat and continuous unidirectional fibers respectively experienced the highest and the lowest reductions properties in all environmental conditions. The maximum reductions in tensile strength for chopped strand mat laminates were about 7%, 32%, and 42% in the dry freeze/thaw, wet freeze/thaw and UV with moisture environments, respectively. The corresponding decreases in the tensile strength for unidirectional laminates were negligible, 17% and 23%, whereas those for the woven laminates were and 7%, 24%, and 34%. [ABSTRACT FROM AUTHOR]

The antioxidant effect of salidroside has been proven, but its role in liver injury is poorly understood. In this study, we aimed to evaluate the protective effects and mechanism of salidroside on liver injury induced by carbon tetrachloride (CCl4) in vivo. Mice were pretreated with salidroside (60 mg/kg, intraperitoneally injected, i.p.) once per day for 14 consecutive days and then administered with CCl4 (15.95 g/kg, i.p.) for 24 h to produce a liver injury model. Salidroside attenuated hepatic transaminase elevation in serum and ameliorated liver steatosis and necrosis, thereby suggesting its protective effect on the liver. Salidroside antagonized CCl4-induced toxicity by equilibrating antioxidation system, thereby inhibiting reactive oxygen species accumulation, and restoring mitochondrial structure and function. Salidroside exerts antioxidant and liver-protective effects by selectively inhibiting the activation of genes, including growth arrest and DNA -damage-inducible 45 α (Gadd45a), mitogen-activated protein kinase 7 (Mapk7), and related RAS viral oncogene homolog 2 (Rras2), which induce oxidative stress in the mitogen-activated protein kinase pathway. These results revealed that salidroside can protect the liver from CCl4-induced injury by resisting oxidative stress and protecting mitochondrial function. [ABSTRACT FROM AUTHOR]

The antioxidant effect of salidroside has been proven, but its role in liver injury is poorly understood. In this study, we aimed to evaluate the protective effects and mechanism of salidroside on liver injury induced by carbon tetrachloride (CCl 4 ) in vivo. Mice were pretreated with salidroside (60 mg/kg, intraperitoneally injected, i.p.) once per day for 14 consecutive days and then administered with CCl 4 (15.95 g/kg, i.p.) for 24 h to produce a liver injury model. Salidroside attenuated hepatic transaminase elevation in serum and ameliorated liver steatosis and necrosis, thereby suggesting its protective effect on the liver. Salidroside antagonized CCl 4 -induced toxicity by equilibrating antioxidation system, thereby inhibiting reactive oxygen species accumulation, and restoring mitochondrial structure and function. Salidroside exerts antioxidant and liver-protective effects by selectively inhibiting the activation of genes, including growth arrest and DNA -damage-inducible 45 α (Gadd45a), mitogen-activated protein kinase 7 (Mapk7), and related RAS viral oncogene homolog 2 (Rras2), which induce oxidative stress in the mitogen-activated protein kinase pathway. These results revealed that salidroside can protect the liver from CCl 4 -induced injury by resisting oxidative stress and protecting mitochondrial function.

The Mustang, Musculoskeletal Temporally Activated Novel-1 Gene (MUSTN1) plays an important role in regulating musculoskeletal development in mammals. We evaluated the developmental and tissue-specific regulation of MUSTN1 mRNA and protein abundance in Erlang Mountainous (EM) chickens. Results indicated that MUSTN1 mRNA/protein was expressed in most tissues with especially high expression in heart and skeletal muscle. The MUSTN1 protein localized to the nucleus in myocardium and skeletal muscle fibers. There were significant differences in mRNA and protein abundance among tissues, ages and between males and females. In conclusion, MUSTN1 was expressed the greatest in skeletal muscle where it localized to the nucleus. Thus, in chickens MUSTN1 may play a vital role in muscle development.