Evaluating Mechanical Properties of Macro-Synthetic Fiber-Reinforced Concrete with Various Types and Contents

Concrete, as one of the most widely used construction materials, has a brittle behavior. Adding fibers with different types and contents would affect the ductility behavior and mechanical properties of concrete. Hence, an experimental study was conducted to investigate effects of type and content of polymer fibers on mechanical properties of fiber-reinforced concrete such as flexural strength, compressive strength, indirect tensile strength, and elastic modulus. In the present research, the concrete samples were made and, then, evaluated, using three different types of polymer fibers, including twisted, barchip, and fibrillated, with the contents of 0.2, 0.4, and 0.6 volume percentages, respectively. The results showed that by adding fibers to the concrete samples, the flexural and tensile strength was increased by 19.6–81.69% and 0.84–34.29%, respectively; besides, the addition of the fibers to concrete reduced the compressive strength and elasticity modulus by 4.57–26.32% and 12.48–37.08%, respectively. The concrete containing twisted and barchip fibers, despite the different types of fibers, had similar flexural performance.Бетон как один из наиболее широко используемых строительных материалов характеризуется хрупкими свойствами. Добавление в бетон волокон различного типа и содержимого влияет на податливость и механические характеристики бетона. Проведено экспериментальное исследование для оценки влияния типа и содержимого полимерных волокон на механические свойства армированного волокнами бетона (прочность при изгибе, прочность при сжатии, косвенный предел прочности при растяжении, модуль упругости). Образцы из бетона были выполнены с применением трех различных типов полимерного волокна (скрученное, щепкообразные прутки, фибриллированное) с содержанием 0.2, 0.4 и 0.6 об.% соответственно. Установлено, что, добавление волокна в образцы из бетона повышает пределы прочности на изгиб и растяжение на 19.6–81.69% и 0.84–34.29% соответственно и понижает предел прочности при сжатии и модуль упругости на 4.57–26.32% и 12.48–37.08% соответственно. Бетон, содержащий скрученные волокна и волокна в виде щепкообразных прутков, несмотря на различные типы волокон, имеет одинаковые изгибные характеристики.Бетон як один із будівельних матеріалів, що найбільш широко використовується, має крихкі властивості. Добавляння в бетон різного типу і вмісту волокон впливає на його піддатливість і механічні характеристики. Експериментально досліджено вплив типу і вмісту полімерних волокон на механічні характеристики армованого волокнами бетону (міцність при згині і при стиску, умовна границя міцності при розтязі, модуль пружності). Зразки з бетону виготовляли з добавлянням трьох типів полімерного волокна (скручене 0,2 об.%, тріскоподібні прутики 0,4 об.%, фібрильоване 0,6 об.%). Установлено, що добавляння волокна в зразки з бетону підвищує границі міцності при згині і розтязі на 19,6...81,69% та 0,84...34,29% відповідно і знижує границю міцності при стиску і модуль пружності на 4,57...26,32% і 12,48...37,08% відповідно. Назважаючи на різні типи волокон (скручене, тріскоподібні прутики), бетон має однакові характеристики при згині

Cyclodextrin modulation of gallic acid in vitro antibacterial activity

The substitution of large spectrum antibiotics for natural bioactive molecules (especially polyphenolics) for the treatment of wound infections has come into prominence in the pharmaceutical industry. However, the use of such molecules depends on their stability during environmental stress and on their ability to reach the action site without losing biological properties. The application of cyclodextrins as a vehicle for polyphenolics protection has been documented and appears to enhance the properties of bioactive molecules. Therefore, the encapsulation of gallic acid, an antibacterial agent with low stability, by -cyclodextrin, (2-hydroxy) propyl--cyclodextrin and methyl--cyclodextrin, was investigated. Encapsulation by -cyclodextrin was confirmed for pH 3 and 5, with similar stability parameters. The (2-hydroxy) propyl--cyclodextrin and methyl--cyclodextrin interactions with gallic acid were only confirmed at pH 3. Among the three cyclodextrins, better gallic acid encapsulation were observed for (2-hydroxy) propyl--cyclodextrin, followed by -cyclodextrin and methyl--cyclodextrin. The effect of cyclodextrin encapsulation on the gallic acid antibacterial activity was also analysed. The antibacterial activity of the inclusion complexes was investigated here for the first time. According to the results, encapsulation of gallic acid by (2-hydroxy) propyl--cyclodextrin seems to be a viable option for the treatment of skin and soft tissue infections, since this inclusion complex has good stability and antibacterial activity.The authors are grateful for the FCT Strategic Project PEst-OE/EQB/LA0023/2013 and the Project "BioHealth-Biotechnology and Bioengineering approaches to improve health quality", Ref. NORTE-07-0124-FEDER-000027, co-funded by the "Programa Operacional Regional do Norte" (ON.2-O Novo Norte), QREN, FEDER. The authors also acknowledge the project "Consolidating Research Expertise and Resources on Cellular and Molecular Biotechnology at CEB/IBB", Ref. FCOMP-01-0124-FEDER-027462. This work is, also, funded by FEDER funds through the Operational Programme for Competitiveness Factors-COMPETE and National Funds through FCT-Foundation for Science and Technology under the project PEst-C/CTM/UI0264/2011. Additionally, the authors would like to thank the FCT for the grant for E. Pinho (SFRH/BD/62665/2009)

Clinical Findings of Arthroscopic Release in Treatment of ‎Primary Frozen Shoulder ‎

BACKGROUND AND OBJECTIVE: Frozen shoulder is a common condition, characterized by pain and restrictions in shoulder movements. Different non-surgical and surgical methods are used to overcome this condition. Given the high prevalence of frozen shoulder among the working class in communities, re-empowerment is essential for individuals’ return to daily activities. Considering the contradictory results reported by previous research, further investigations are required in this area. Therefore, this study aimed to evaluate the clinical findings of arthroscopic release in treatment of primary frozen shoulder. METHODS: This cross-sectional study was performed on all patients with primary frozen shoulder, referring to Bahonar and Shafa Hospitals of Kerman, Iran. These patients were candidates for surgery due to unsuccessful supportive treatment. First, American Shoulder and Elbow Surgeons (ASES) assessment form (score: 0-100) and Simple Shoulder Test (a 12-item questionnaire) were completed before surgery. Then, all patients underwent arthroscopic release and examinations. The assessment forms were completed again within 3 and 12 months after surgery. FINDINGS: Overall, 15 patients with the mean age of 50.57±12.01 years were included in this study. There was a significant difference in the mean score of SST before (10.21±0.98) and after (10.98±1.05) surgery (p=0.034). Also, patients’ performance at 12-month follow-up significantly improved, compared to the three-month follow-up (p=0.014). There was a significant difference in the mean scores of ASES test before and after surgery (p=0.007). Also, the mean score of ASES test was higher at 12-month follow-up, compared to the three-month follow-up (p=0.019). CONCLUSION: Overall, arthroscopic release could help relieve pain and improve the range of shoulder movements in patients. Moreover, it could help patients return to their daily activities and regain their productivity. In fact, this technique facilitates simultaneous diagnosis and treatment of shoulder joint problems

Determinant physiological factors of simulated BMX race

© 2021 European College of Sport Science. Evaluating the physiological demands of BMX cycling on a track provides coaches with the information required to prescribe more effective training programmes. To determine the relative importance of physiological factors during simulated BMX race, 12 male riders (age 19.2 ± 3.5 years, height 1.76 ± 0.06 m, mass 68.5 ± 4.3 kg) completed a maximum aerobic capacity ((Figure presented.)) test in a laboratory, and a week later, completed six laps on a BMX track interspersed by 15 min passive recovery. Peak power, immediate post-lap (Figure presented.), blood lactate, and heart rate were measured in each lap. Peak power to weight ratio was significantly correlated with lap time, however, the strength of this association decreased in each subsequent lap. Mean (Figure presented.) was greater than 80% of laboratory-measured (Figure presented.) in every lap, indicating a strong contribution of the aerobic energy system during BMX racing. This study also identified that mean blood lactate was significantly associated with lap time, which showed the importance of the anaerobic energy system contribution to BMX race. Despite the short period of pedalling during BMX racing, both aerobic and anaerobic energy systems are important contributors to lap performance. Coaches should consider maximising both anaerobic power and aerobic capacity to improve riders’ overall performance in multiple laps