A Review on the Physical Parameters Affecting the Bond Behavior of FRP Bars Embedded in Concrete.

The present study is a detailed literal survey on the bond behavior of FRP (Fiber Reinforced Polymer) reinforcing bars embedded in concrete. There is an urgent need for the accurate assessment of the parameters affecting the FRP-concrete bond and quantification of these effects. A significant majority of the previous studies could not derive precise and comprehensive conclusions on the effects of each of these parameters. The present study aimed at listing all of the physical parameters affecting the concrete-FRP bond, presenting the effects of each of these parameters based on the common opinions of the previous researchers and giving reasonable justifications on these effects. The studies on each of the parameters are presented in detailed tables. Among all listed parameters, the surface texture was established to have the most pronounced effect on the FRP-concrete bond strength. The bond strength values of the bars with coarse sand-coating exceeded the respective values of the fine sand-coated ones. However, increasing the concrete strength was found to result in a greater improvement in bond behavior of fine sand-coated bars due to the penetration of concrete particles into the fine sand-coating layer. The effects of fiber type, bar diameter and concrete compressive strength on the bar bond strength was shown to primarily originate from the relative slip of fibers inside the resin of the bar, also known as the shear lag effect.

Evaluation and Multi-Objective Optimization of Lightweight Mortars Parameters at Elevated Temperature via Box-Behnken Optimization Approach.

In this research, the mechanical properties of lightweight mortars containing different percentages of additional powder materials has been investigated using response surface methodology (RSM). Box-Behnken design, one of the RSM techniques, was used to study the effects of silica fume content (5, 10, and 15%), vermiculite/cement (V/C) ratio (4, 6, and 8), and temperature (300, 600, and 900 °C) on the ultrasonic pulse velocity (UPV), bending strength, and compressive strength of lightweight mortars. Design expert statistical software was accustomed to determining and evaluating the mix-design of materials in mortar mixtures and temperature effect on mortars. After preliminary experimental research of the relationships between independent and response variables, regression models were built. During the selection of the model parameters, F value, p-value, and R2 values of the statistical models were taken into account by using the backward elimination technique. The results showed a high correlation between the variables and responses. Multi-objective optimization results showed that the critical temperatures for different levels of silica fume (5-10-15%) were obtained as 371.6 °C, 306.3 °C, and 436 °C, respectively, when the V/C ratio kept constant as 4. According to the results obtained at high desirability levels, it is found that the UPS values varied in the range of 2480-2737 m/s, flexural strength of 3.13-3.81 MPa, and compressive strength of 9.9-11.5 MPa at these critical temperatures. As a result of this research, RSM is highly recommended to evaluate mechanical properties where concrete includes some additional powder materials and was exposed to high temperature.

[Influence of tobacco smoking on physical efficiency of young woman (part I)]. / Wplyw palenia papierosów na wydolnosc fizyczna mlodych kobiet (czesc I).

For over 20 years Poland has been one of the countries with the world's highest consumption of tobacco. In view of the widespread popularity of this addition, of particular importance becomes the problem of women becoming addicted to tobacco smoke. Therefore, the objective of this work was to develop and conduct preliminary surveys aimed at the determination of the scale of active and passive cigarette smoking among young women as well as the assessment of smoking on physical fitness. The research took a form of an anonymous questionnaire administered to 80 female secondary school graduates who were passing their entrance examinations to the University of Physical Education in Wroclaw. The physical capacities were assessed on the basis of fitness tests and their results were subject to statistical analysis. One identified a significant impact of cigarette smoking on reducing the physical fitness and, in consequence, lower scores in the fitness test among smoking girls when compared to the scores of non-smoking girls (respectively 17.5+/-2.0; 21.0+/-4.5; p<0.0001). It was shown that smoking more than 10 cigarettes per day and on the fitness test day has considerably influenced their physical fitness (p<0.002; p<0.0004). Moreover, smoking women devoted less time to exercises and had a higher BMI when compared to non-smoking women.

Maspin and c-erbB-2 expression in correlation with microvessel density in invasive ductal breast cancer.

Maspin is a unique member of the serpin family involved in regulation of cell migration, apoptosis and angiogenesis in breast and prostate cancers. In this study maspin expression in comparison with c-erbB-2 (HER2/neu) oncogene expression and microvessel density was investigated. The examined material included specimens of primary invasive ductal breast cancer derived from 69 patients. They were analyzed immunocytochemically to assess maspin and c-erbB-2 expression, as well as microvessel density using endothelium marker CD31. In the studied cancers, maspin expression in cancer cells was detected in more than half of the cases (50.73%). Although statistically insignificant (p=0.27), maspin expression showed decreasing tendency with the increase of tumor grade. C-erbB-2 oncogene expression was observed in 78.26% of the examined cancers. Statistically significant positive correlation was found between c-erbB-2 expression and tumor grade (p<0.005). Analysis of the dependence between maspin and c-erbB-2 expression exhibited statistically significant inverse correlation (p<0.001). Mean microvessel density (MVD) of the studied cancers was 71.64 (SD=19.36). MVD decreased with the increase of maspin expression, whereas in the cases showing c-erbB-2 overexpression MVD was clearly higher. Both correlations were statistically significant (p<0.005). In conclusion, it could be stated that increase in maspin expression is associated with weaker expression of c-erbB-2 oncogene and lower microvessel density, which implies a significant role of maspin in tumor biology. However, the exact mechanism of maspin action (including its potential role in angiogenesis), as well as the assessment of its prognostic significance in breast cancer require further studies.