Evaluation of Fluidity and Strength of High-Early-Strength Cement-Based Repair Materials by Adding SB Latex and Wollastonite Mineral Fibers.

Concrete structures often fail to perform their original functions due to problems such as deterioration and damage over time. Therefore, various repair materials have been studied to maintain deteriorated concrete structures. This study experimentally investigated the mechanical properties of high-early-strength cement-based repair materials for spraying. For spraying, the cement-based materials should have adoptable fluidity and strength: 200 ± 100 mm for flow; 20 MPa at 24 h and 40 MPa at 28 days for compressive strength, and 8 MPa at 28 days for flexural strength. Wollastonite mineral fibers (3-5 wt.%) and styrene-butadiene (SB) latex (5-7 wt.%) were studied to enhance this requirement. Fluidity was evaluated by flow test and measuring the heat of hydration; mechanical properties were evaluated in terms of compressive and flexural strength. The cement-to-silica sand ratio (C:S ratio) was also applied differently to adjust the pot life of polymer cement-based material (1:1 and 1:1.5) as a binder. Because wollastonite mineral fibers and SB latex affect workability, the water-to-binder ratio was regulated to reach the target flow according to the amount of wollastonite mineral fibers and SB latex. Regardless of the C:S ratio, all studied mixtures met the target 28 day compressive strength at 24 h, decreasing in strength with increasing amounts of wollastonite mineral fibers and latex. Flexural strength also fulfilled the target value, and it increased with increasing amounts of wollastonite mineral fibers and latex, unlike compressive strength. The optimal mix proportion of high-early-strength cement-based repair materials constituted 3 wt.% wollastonite mineral fibers and 5 wt.% SB latex as the binder in a C:S ratio of 1:1.5.

Effects of Wollastonite Fiber and Styrene-Butadiene Latex Polymer on the Long-Term Durability of Cement-Based Repair Materials.

Concrete structures are constructed in various geographical environments and climates, and frequently fail to fulfill their original functions over time due to issues such as aging and damage. Research on concrete structure repair materials is being conducted to solve these problems. This study evaluated the durability of a repair material composed of ultra-rapid hardening cement, styrene-butadiene (SB) latex polymer, and wollastonite mineral fiber. The performance targets were as follows: compressive strength of 20 MPa at 1 day of age and 45 MPa at 28 days of age, chloride ion charge passed of less than 1000 Coulombs, carbonation depth of 20 mm or less, and resistance to repeated freezing and thawing (relative dynamic modulus of elasticity) of 80% or more. The ultra-rapid hardening cement:silica sand ratio of 1:1.5 was the experimental variable, and the unit weight of each material in the mix proportion was determined to satisfy the flow requirement of 200 ± 5 mm. This flow ensured sufficient fluidity for spraying, which is the most widely used method for applying repair material. Wollastonite mineral fiber and SB latex polymer were added at 3% and 5% of the unit weight of the binder, respectively. The mechanical property of the repair material was evaluated through compressive strength, and durability was evaluated through chloride ion penetration, alkali resistance, resistance to carbonation, water absorption, and repeated freezing and thawing tests. The compressive strength satisfied both target values, regardless of the addition of SB latex polymer and wollastonite mineral fiber. The chloride ion penetration test, which was used as an indicator of durability, showed that mixtures without SB latex and wollastonite mineral fiber were not satisfied the target charge passed of 1000 Coulombs, while mixtures with latex and mineral fiber reached the target value. Notably, the co-addition of latex and wollastonite fiber showed the highest resistance to chloride ion penetration, alkali ion, carbonation, repeated freezing and thawing, and the least absorption. The results confirmed that the durability of the repair material based on ultra-rapid hardening cement was most effectively improved by the co-addition of SB latex polymer and wollastonite mineral fiber.

Mechanical and Durability Properties of Latex-Modified Hybrid Fiber-Reinforced Roller-Compacted Rapid-Set Cement Concrete for Pavement Repair.

This study evaluated the mechanical properties and durability performance of latex-modified hybrid fiber-reinforced roller-compacted rapid-set cement concrete (LMHFRCRSC) for emergency repair of concrete pavement. Experimental parameters included the blend ratio of the hybrid fiber, which comprised natural jute fiber (0-0.2 vol.%) and structural synthetic fiber (0-2 vol.%). The mechanical performance of LMHFRCRSC of various blend ratios was evaluated in terms of compressive, flexural, and splitting tensile strength. Durability assessment included chlorine ion penetration and abrasion resistance measurements. Compressive and flexural strength values of 21 and 3.5 MPa, respectively, were the set targets after 4 h of curing; a compressive strength of 35 MPa, a flexural strength of 4.5 MPa, a splitting tensile strength of 4.2 MPa, and chloride ion penetration of 2000 C or less were required after 28 days of curing. Our test results confirmed that all mix proportions satisfied the target values, regardless of the blend ratio of the hybrid fiber. Specifically, the mechanical performance of the concrete improved as the blend ratio of the structural synthetic fiber increased. With regard to durability, a greater amount of jute fiber, a hydrophilic fiber, enhanced the concrete's durability. Additionally, incorporating jute fiber of 0.6 kg/m3 provided excellent chlorine ion penetration resistance. The optimal blend ratio for the hybrid fiber was natural jute fiber at 0.6 kg/m3 and structural synthetic fiber at 13.65 kg/m3 (mix: J0.6 + P13.65); with this mix proportion, a chloride ion penetration amount of 1000 C or less and maximum mechanical performance were achieved.

Evaluation of Health Literacy and Depression Literacy Among Korean Americans.

Low health literacy is closely related to a higher rate of hospitalization and of emergency services usage, leading to billions of dollars in avoidable health care costs and contributing to individuals' poor physical and mental health. While Korean Americans (KAs) have a high prevalence of general health and mental health problems, relatively little is known about their health and mental health literacy, specifically their depression literacy. This study aims to evaluate KAs' health literacy and depression literacy, as related to sociodemographic characteristics. An exploratory study was conducted with 681 community-residing adult KAs using the Center for Epidemiologic Studies Depression (CES-D) Scale, the Depression Literacy Questionnaire (D-Lit), and the One-Question Health Literacy Scale. Data analyses were performed using one-way analysis of variance and ordinal logistic regression of health literacy, a multiple linear regression model of depression literacy. Findings indicate a positive correlation between depression literacy and health literacy. Health literacy was also significantly related to religion, English language proficiency, income, education, and perceived physical health. Additionally, depression literacy was significantly related to age, Korean language preference over English, and education. Health literacy and depression literacy education are warranted to address low health literacy and depression literacy among KAs to reduce their health and mental health disparities.

Analysis of metal(loid)s contamination and their continuous input in soils around a zinc smelter: Development of methodology and a case study in South Korea.

Soil contamination due to atmospheric deposition of metals originating from smelters is a global environmental problem. A common problem associated with this contamination is the discrimination between anthropic and natural contributions to soil metal concentrations: In this context, we investigated the characteristics of soil contamination in the surrounding area of a world class smelter. We attempted to combine several approaches in order to identify sources of metals in soils and to examine contamination characteristics, such as pollution level, range, and spatial distribution. Soil samples were collected at 100 sites during a field survey and total concentrations of As, Cd, Cr, Cu, Fe, Hg, Ni, Pb, and Zn were analyzed. We conducted a multivariate statistical analysis, and also examined the spatial distribution by 1) identifying the horizontal variation of metals according to particular wind directions and distance from the smelter and 2) drawing a distribution map by means of a GIS tool. As, Cd, Cu, Hg, Pb, and Zn in the soil were found to originate from smelter emissions, and As also originated from other sources such as abandoned mines and waste landfill. Among anthropogenic metals, the horizontal distribution of Cd, Hg, Pb, and Zn according to the downwind direction and distance from the smelter showed a typical feature of atmospheric deposition (regression model: y = y0 + αe-ßx). Lithogenic Fe was used as an indicator, and it revealed the continuous input and accumulation of these four elements in the surrounding soils. Our approach was effective in clearly identifying the sources of metals and analyzing their contamination characteristics. We believe this study will provide useful information to future studies on soil pollution by metals around smelters.

Effects on the Physical and Mechanical Properties of Porous Concrete for Plant Growth of Blast Furnace Slag, Natural Jute Fiber, and Styrene Butadiene Latex Using a Dry Mixing Manufacturing Process.

To evaluate the effects of industrial by-products materials on the performance of porous concrete for plant growth, this study investigated the physical, strength, and freeze/thaw resistances of porous concrete for plant growth, prepared by replacing cement with blast furnace slag powder at 60% by weight, and replacing natural stone aggregates with coarse blast furnace slag aggregates at rates of 0%, 20%, 40%, 60% and 100% by weight. In addition, the effects of adding natural jute fiber and styrene butadiene (SB) latex to these concrete mixtures were evaluated. The void ratio, compressive strength, and freeze/thaw resistance of the samples were measured. With increasing replacement rate of blast furnace aggregates, addition of latex, and mixing of natural jute fiber the void ratio of the concrete was increased. Compressive strength decreased as the replacement rate of blast-furnace slag aggregates increased. The compressive strength decreased after 100 freeze/thaw cycles, regardless of the replacement rate of blast furnace slag aggregates or of the addition of natural jute fiber and latex. The addition of natural jute fiber and latex decreased the compressive strength after 100 freeze/thaw cycles. The test results indicate that the control mixture satisfied the target compressive strength of 10 MPa and the target void ratio of 25% at replacement rates of 0% and 20% for blast furnace aggregates, and that the mixtures containing latex satisfied the criteria up to an aggregate replacement rate of 60%. However, the mixtures containing natural jute fiber did not satisfy these criteria. The relationship between void ratio and residual compressive strength after 100 freeze/thaw cycles indicates that the control mixture and the mixtures containing jute fiber at aggregate replacement rates of 20% and 40% satisfied the target void ratio of 25% and the target residual compressive strength of over 80% after 100 freeze/thaw cycles. The mixtures containing latex and aggregate replacement rates up to 60% satisfied the target void ratio and compressive strength.

Effect of Industrial By-Products on Unconfined Compressive Strength of Solidified Organic Marine Clayey Soils.

The use of industrial by-products as admixture to ASTM Type I cement (ordinary Portland cement (OPC)) was investigated with the objective of improving the solidification of organic marine clayey soils. The industrial by-products considered in this paper were oyster-shell powder (OSP), steelmaking slag dust (SMS) and fuel-gas-desulfurized (FGD) gypsum. The industrial by-products were added to OPC at a ratio of 5% based on dry weight to produce a mixture used to solidify organic marine clayey soils. The dosage ratios of mixtures to organic marine clayey soils were 5, 10 and 15% on a dry weight basis. Unconfined compressive strength (UCS) test after 28 days revealed that the highest strength was obtained with the OPC + SMS 15% mixing ratio. The UCS of specimens treated with this mixture was >500 kPa, compared with 300 kPa for specimens treated with a 15% OPC + OSP mixture and 200 kPa when 15% of OPC was used alone. These results were attributed to the more active hydration and pozzolanic reaction of the OPC + SMS mixture. This hypothesis was verified through X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses, and was confirmed by variations in the calcium carbonate (CaCO3) content of the materials during curing.

Mechanical and Permeability Characteristics of Latex-Modified Pre-Packed Pavement Repair Concrete as a Function of the Rapid-Set Binder Content.

We evaluated the strength and durability characteristics of latex-polymer-modified, pre-packed pavement repair concrete (LMPPRC) with a rapid-set binder. The rapid-set binder was a mixture of rapid-set cement and silica sand, where the fluidity was controlled using a latex polymer. The resulting mix exhibited a compressive strength of ¥21 MPa and a flexural strength of ¥3.5 MPa after 4 h of curing (i.e., the traffic opening term for emergency repairs of pavement). The ratio of latex polymer to rapid-set binder material was varied through 0.40, 0.33, 0.29, and 0.25. Mechanical characterization revealed that the mechanical performance, permeability, and impact resistance increased as the ratio of latex polymer to rapid-set binder decreased. The mixture exhibited a compressive strength of ¥21 MPa after 4 h when the ratio of latex polymer to rapid-set binder material was ¤0.29. The mixture exhibited a flexural strength of ¥3.5 MPa after 4 h when the ratio of latex polymer to rapid-set binder material was ¤0.33. The permeability resistance to chloride ions satisfied 2000 C after 7 days of curing for all ratios. The ratio of latex polymer to rapid-set binder material that satisfied all conditions for emergency pavement repair was ¤0.29.

Acacetin (5,7-dihydroxy-4'-methoxyflavone) exhibits in vitro and in vivo anticancer activity through the suppression of NF-κB/Akt signaling in prostate cancer cells.

Acacetin (5,7-dihydroxy-4'-methoxyflavone) is a flavonoid compound with antimutagenic, antiplasmodial, antiperoxidant, anti-inflammatory and anticancer effects. However, the molecular targets and pathways underlying the anticancer effects of acacetin are yet to be elucidated. In this study, we investigated whether acacetin induces apoptosis in the human prostate cancer cell line, DU145. The results of 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assays revealed that cell viability decreased in a dose- and time-dependent manner in response to acacetin. 4',6-Diamidino-2-phenylindole (DAPI) staining revealed that chromatin condensation significantly increased in a dose-dependent manner. Flow cytometric analysis indicated that acacetin suppressed the viability of DU145 cells by inducing apoptosis. Western blot anlaysis of various markers of signaling pathways revealed that acacetin targets the Akt and nuclear factor (NF)-κB signaling pathways by inhibiting the phosphorylation of IκBα and NF-κB in a dose-dependent manner. Consistent with its ability to induce apoptosis, the acacetin-mediated inhibition of the pro-survival pathway, Akt, and of the NF-κB pathway was accompanied by a marked reduction in the levels of the NF-κB­regulated anti-apoptotic proteins, Bcl-2 and X-linked inhibitor of apoptosis protein (XIAP), as well as of the proliferative protein, cyclooxygenase (COX)-2. We further evaluated the effects of acacetin on prostate cancer using mice subcutaneously injected with DU145 prostate cancer cells. The acacetin-treated nude mice bearing DU145 tumor xenografts exhibited significantly reduced tumor size and weight, due to the effects of acacetin on cancer cell apoptosis, as determined by terminal deoxyribonucleotide transferase-mediated dUTP nick end-labeling (TUNEL) assay. Our findings suggest that acacetin exerts antitumor effects by targeting the Akt/NF-κB signaling pathway. Rurther investigations on this flavonoid are warranted to evaluate its potential use in the prevention and therapy of prostate cancer.