Functionally modified,melt‐electrospun thermoplastic polyurethane mats for wound‐dressing applications

The electrospinning of a polymer melt is an interesting process for medical applications because it eliminates the cytotoxic effects of solvents in the electrospinning solution. Wound dressings made from thermoplastic polyurethane (TPU), particularly as a porous structured electrospun membrane, are currently the focus of scientific and commercial interest. In this study, we developed a functionalized fibrillar structure as a novel antibacterial wound‐dressing material with the melt‐electrospinning of TPU. The surface of the fibers was modified with poly(ethylene glycol) (PEG) and silver nanoparticles (nAg's) to improve their wettability and antimicrobial properties. TPU was processed into a porous, fibrous network of beadless fibers in the micrometer range (4.89 ± 0.94 μm). The X‐ray photoelectron spectroscopy results and scanning electron microscopy images confirmed the successful incorporation of nAg's onto the surface of the fiber structure. An antibacterial test indicated that the PEG‐modified nAg‐loaded TPU melt‐electrospun structure had excellent antibacterial effects against both a Gram‐positive Staphylococcus aureus strain and Gram‐negative Escherichia coli compared to unmodified and PEG‐modified TPU fiber mats. Moreover, modification with nAg's and PEG increased the water‐absorption ability in comparison to unmodified TPU. The cell viability and proliferation on the unmodified and modified TPU fiber mats were investigated with a mouse fibroblast cell line (L929). The results demonstrate that the PEG‐modified nAg‐loaded TPU mats had no cytotoxic effect on the fibroblast cells. Therefore, the melt‐electrospun TPU fiber mats modified with PEG and nAg have the potential to be used as antibacterial, humidity‐managing wound dressings. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40132.     

Identification of bioactive compounds and total phenol contents of cold pressed oils from safflower and camelina seeds

The compositions of fatty acids, tocopherols, polyphenols, sterols, and the total phenol contents of cold pressed oils obtained from five varieties of safflower seeds and ten varieties of camelina seeds cultivated in Turkey were determined. Total phenol contents of safflower oils were higher (272.20–525.30 mg GAE/kg) than camelina seed oils (25.90–63.70 mg GAE/kg). Apigenin, luteolin, tyrosol, syringic acid, 3-hydroxytyrosol, p-coumaric acid and sinapic acid were detected in seed oils. Camelina seed oils were rich in tocopherol (144.11–168.69 mg/100 g). γ-Tocopherol was the predominant tocopherol in camelina seed oils consisting of averagely 80% of total tocopherol, while α-tocopherol was the main compound of safflower seed oils, representing 97.85–98.53% of total tocopherols. β-Sitosterol was the major sterol in both type of seed oils. Its concentration ranged between 92.51–121.83 mg/100 g and 80.52–25.54 mg/100 g in safflower seed and camelina oils, respectively. Camelina seed oils contained 22.31–26.57% linolenic acid, 21.25–24.05% linoleic acid and 19.46–21.47% oleic acid, whereas safflower seed oils mainly consisted of linoleic (28.03–76.85%) and oleic (13.01–62.61%) acids.     

Bis(monoacylglycero)phosphate as a Macrophage Enriched Phospholipid

Bis(monoacylglycero)phosphate (BMP) is a structural isomer of phosphatidylglycerol (PtdGro) with an unusual sn‐1:sn‐1′ fatty acyl configuration and is found almost exclusively in late endosomes/lysosomes. BMP comprises only about 1–2 % of the total phospholipids in most mammalian cells, but accumulates in tissues of humans and animals with lysosomal storage disorders including the gangliosidoses. Total BMP content was significantly greater in cells of macrophage/microglial origin than in cells of macroglial origin. BMP composition was similar in tumorigenic/metastatic macrophages and non‐tumorigenic macrophages/microglia. Finally, BMP fatty acid composition differed between cells grown in culture and obtained in vivo suggesting an influence from growth environment.     

Determining Attribute Weights in a CBR Model for Early Cost Prediction of Structural Systems

This paper compares the performance of three optimization techniques, namely feature counting, gradient descent, and genetic algorithms (GA) in generating attribute weights that were used in a spreadsheet-based case based reasoning (CBR) prediction model. The generation of the attribute weights by using the three optimization techniques and the development of the procedure used in the CBR model are described in this paper in detail. The model was tested by using data pertaining to the early design parameters and unit cost of the structural system of 29 residential building projects. The results indicated that GA-augmented CBR performed better than CBR used in association with the other two optimization techniques. The study is of benefit primarily to researchers as it compares the impact attribute weights generated by three different optimization techniques on the performance of a CBR prediction tool.     

Testing Preorders for Probabilistic Processes

We present a testing preorder for probabilistic processes based on a quantification of the probability with which processes pass tests. The theory enjoys close connections with the classical testing theory of De Nicola and Hennessy in that whenever a process passes a test with probability 1 (respectively some nonzero probability) in our setting, then the process must (respectively may) pass the test in the classical theory. We also develop an alternative characterization of the probabilistic testing preorders that takes the form of a mapping from probabilistic traces to the interval [0, 1], where a probabilistic trace is an alternating sequence of actions and probability distributions over actions. Finally, we give proof techniques, derived from the alternative characterizations, for establishing preorder relationships between probabilistic processes. The utility of these techniques is demonstrated by means of some simple examples.     

CFRP Effect on the Buckling Behavior of Dented Cylindrical Shells

Considering that the use of thin-walled shells is expanding every day, it is important to examine the problem of instability in this form of structure. Many steel structures such as high-water tanks, water and oil reservoirs, marine structures, and pressure vessels, including shell elements, are under stress tension. In addition, shell elements are subject to instability owing to the loads applied. Ten thin-walled cylindrical shell specimens in two groups with different dent depths of t_c and 2t_c, and the different dent number subject to uniform external pressure were tested in the present research (t_c is the thickness of cylindrical shell). The samples were modified to include either one or two dent line with amplitudes of h/3 in height (h the height of cylinder shell). Moreover, CFRP Strips on the dent depth was used in one of the groups. The results of testing under different theories and codes are compared.

     

Developing a passive house with a double-skin envelope based on energy and airflow performance

This research originated from an interest in developing products with a holistic and interdisciplinary systems engineering approach, toward fostering sustainability. A comprehensive method which helps designers make better decisions in the earliest design stage was applied for conceptual model development and comparison. The study developed a new-design passive house with a double-skin envelope that delivers better energy consumption performance for heating and cooling relative to a conventional reference house, while achieving comfort-level indoor temperatures. A single-façade reference house was designed with the identical geometry, material and conditions of the new house living quarters, in order to demonstrate the new house performance using a valid comparison. The new house and reference house were simulated cases and were not calibrated by actual models. The energy simulations demonstrated that the heating and cooling demands of the new house were 19.1% and 18.8% lower than those of the reference house, respectively. Furthermore, fluid dynamics behavior of the air inside the double-skin envelope was analyzed to demonstrate the airflow’s contribution to the energy performance. Computational fluid dynamics simulations revealed that turbulent airflow in the underground space on summer day increased heat transfer, and laminar airflow in the double-skin roof on winter night decreased such transfer.