Electrospinning, which is a fiber fabrication technique using electrical forces to produce fibers with diameters ranging from nanometers to several micrometers, can be used to prepare materials mimicking the extracellular matrix proteins for potential use as tissue engineering scaffolds. In this study, nanofibrous mats of chitosan (CH) and poly(lactic acid-co-glycolic acid) (PLGA) having fiber diameters between 167 to 525 nm, and containing hydroxyapatite (HAp), were prepared by electrospinning technique. Morphological, chemical, thermal and degradation tests and cell affinity tests were carried out. Chitosan mats were stable in aqueous media and showed degradability in the presence of lysozyme. In PBS solution, PLGA mats disintegrated completely in 2 weeks. Meanwhile, CH-PLGA mats containing equal amounts of both CH and PLGA fibers and CH-PLGA-HAp samples containing 20 % HAp lost 50 and 40 % of their initial weight in 4 weeks, respectively. Cell culture tests showed that all electrospun fibrous mats promoted SaOs-2 cell attachment and proliferation. However, cell proliferation on CH-PLGA-HAp fibrous mats was higher compared to the others after 7 days demonstrating the positive effect of HAp on cell affinity properties compared to pristine CH or PLGA fibrous scaffolds. 相似文献
Flavonoids, abundant in most of plant species, are widely used in medicine and development studies on phytotherapeutic drugs due to their various biological activities. In the present study, 3 flavonoids, apigenin-7-O-glucoside, apigenin-7-O-rutinoside, and apigenin-7-O-glucuronide, were isolated from Mentha longifolia (L.) Hudson subsp. longifolia by using E. coli WP2 genotoxicity assay guided fractionation procedures. Later, the mutagenic and antimutagenic properties of each flavonoid were evaluated by using the same genotoxicity assay. The results showed that all the test compounds have significant antimutagenic activity at tested concentrations with or without S9 activation. The inhibition rates were between 25.3% (apigenin-7-O-glucoside with S9-2.0 μM/plate) and 59.0% (apigenin-7-O-rutinoside without S9-2.0 μM/plate). In conclusion, the results revealed that the 3 flavonoids from Mentha longifolia (L.) Hudson subsp. longifolia have significant antimutagenic activity, and the findings of the present study are valuable for further investigations, focus on the phytotherapeutic drug discovery. PRACTICAL APPLICATION: Apigenin derivatives can be thought as genetically safe at tested concentrations because they did not show mutagenic activity. Furthermore, they have also significant antimutagenic activity. These are valuable for further research focus on phytotherapeutic drug discovery and development. 相似文献
Kefir is a unique cultured dairy product due to combined lactic acid and alcoholic fermentation of lactose in milk. Kefir is produced by microbial activity of "kefir grains" which have a relatively stable and specific balance of lactic acid bacteria and yeast. Due to the claimed health benefits of kefir which include reduction of lactose intolerance symptoms, stimulation of the immune system, lowering cholesterol, and antimutagenic and anticarcinogenic properties, kefir has become an important functional dairy food and consequently, research on kefir has increased in the past decade. In the following review, recent studies on the functional properties of kefir are reviewed. 相似文献
Carbide lime is a by-product obtained during the manufacturing of acetylene from the reaction of calcium carbide and water. A major portion of carbide lime is dumped in waste deposition areas, creating an environmental problem. Carbide lime and fly ash have possible applications in slope stabilization, subgrade improvement of roads, and soil treatments under shallow foundations. A series of Atterberg limits tests, compaction tests, unconfined compressive strength tests, ultrasonic pulse velocity tests, and wetting–drying tests were performed on carbide lime and fly ash treated clay soils to evaluate the effects of additive content, curing time, strength development, and the effects of wetting and drying. A total of 8% of carbide lime constituted the fixation point, and peak strength was achieved at 12% carbide lime content. A total amount of 25% additive was found as a threshold changing the Atterberg limits. Test results indicated that the strength of the treated soil improved by the existence of carbide lime and fly ash; best performance was observed in 28-day specimens with 10% carbide lime and 20% fly ash content reaching to 8 times larger strength than untreated soil. The failure patterns of the specimens reflected the curing time and wetting–drying effects. Although, the application of wetting–drying cycles deteriorated the treated soil, the presence of carbide lime partially prevented the strength loss. New relationships between normalized strength and curing time depending on carbide lime content were proposed. Furthermore, a linear relationship between the unconfined compressive strength and the ultrasonic pulse velocity of the treated soils was established.
In this work, poly(2-fluoroaniline) (P2FAn) was chemically synthesized with different dopant anions such as p-toluenesulfonate (PTS), 1,3 (6 or 7)-naphthalene trisulfonic acid (NSA), o-aminobenzen sulfonic acid (ABS), sodium dodecyl sulfate (SDS). The P2FAn/PVDF composite cation-exchange membranes were obtained from prepared poly(2-fluoroaniline) by casting method. These membranes were used for the removal of chromium (III) and copper (II) ions from aqueous solution with Donnan dialysis (DD) experiments. The change of surface morphologies of the P2FAn/PVDF composite cation-exchange membranes were investigated by Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). The membrane thickness and their ion-exchange capacities were also measured. The flux values (J) and recovery factor (RF) of chromium (III) and copper (II) were obtained. The flux value of Cu(II) ion was higher than Cr(III) for all of composite membranes because of the hydration volume. 相似文献
This paper addresses the cell formation problem with alternative part routes. The problem is considered in the aspect of the natural constraints of real-life production systems such as cell size, separation and co-location constraints. Co-location constraints were added to the proposed model in order to deal with the necessity of grouping certain machines in the same cell for technical reasons, and separation constraints were included to prevent placing certain machines in close vicinity. The objective is to minimise the weighted sum of the voids and the exceptional elements. A hybrid algorithm is proposed to solve this problem. The proposed algorithm hybridises the modified sub-gradient (MSG) algorithm with a genetic algorithm. MSG algorithm solves the sharp augmented Lagrangian dual problems, where zero duality gap property is guaranteed for a wide class of optimisation problems without convexity assumption. Generally, the dual problem is solved by using GAMS solvers in the literature. In this study, a genetic algorithm has been used for solving the dual problem at the first time. The experimental results show the advantage of combining the MSG algorithm and the genetic algorithm. Although the MSG algorithm, whose dual problem is solved by GAMS solver, and the genetic algorithm cannot find feasible solutions, hybrid algorithm generates feasible solutions for all of the test problems. 相似文献
In today's digital age, the need and interest in personal and portable electronics shows a dramatic growth trend in daily life parallel to the developments in sensors technologies and the internet. Wearable electronics that can be attached to clothing, accessories, and the human body are one of the most promising subfields. The energy requirement for the devices considering the reduction in device sizes and the necessity of being flexible and light, the existing batteries are insufficient and nanogenerators have been recognized a suitable energy source in the last decade. The mechanical energy created by the daily activities of the human body is an accessible and natural energy source for nanogenerators. Fiber-structured functional materials contribute to the increase in energy efficiency due to their effective surface to volume ratio while providing the necessary compatibility and comfort for the movements in daily life with its flexibility and lightness. Among the potential solutions, electrospinning stands out as a promising technique that can meet these requirements, allowing for simple, versatile, and continuous fabrication. Herein, wearable electronics and their future potential, electrospinning, and its place in energy applications are overviewed. Moreover, piezoelectric, triboelectric, and hybrid nanogenerators fabricated or associated with electrospun fibrous materials are presented. 相似文献