Mat.‐wiss. u. Werkstofftech. 7/2017

UV‐reactive electrospinning of keratin/4‐vinyl benzene boronic acid–hydroxyapatite/poly(vinyl alcohol) composite nanofibers

Keratins are the major structural fibrous proteins of hair, feathers, wool, and nail. Because keratin is protein based, cheap, and biocompatible, it has found applications from tissue engineering to textile industry. Simultaneous UV‐reactive electrospinning technique is used to fabricate nanofiber scaffolds with 4‐vinyl benzene boronic acid–hydroxyapatite/poly(vinyl alcohol) composite containing different amounts of keratin. Human hair as keratin supports the scaffolds for cell culture applications in our study. Our aim was to obtain nanofiber scaffolds which were designed to be nontoxic. The structure and the morphology of electrospun membranes were investigated by scanning electron microscopy and Fourier transform infrared spectroscopy technique. For the cell culture applications, endothelium (ECV 304) and sarcoma osteogenic (SAOS) cells were seeded on the electrospun fibrous scaffolds. Nanofiber scaffolds were found to have an average diameter of 350 ± 20 nm. These scaffolds provided a medium for cells to grow. POLYM. COMPOS., 38:1371–1377, 2017. © 2015 Society of Plastics Engineers

Prediction of Protein Interactions by Structural Matching: Prediction of PPI Networks and the Effects of Mutations on PPIs that Combines Sequence and Structural Information

Structural details of protein interactions are invaluable to the understanding of cellular processes. However, the identification of interactions at atomic resolution is a continuing challenge in the systems biology era. Although the number of structurally resolved complexes in the Protein Databank increases exponentially, the complexes only cover a small portion of the known structural interactome. In this chapter, we review the PRISM system that is a protein-protein interaction (PPI) prediction tool-its rationale, principles, and applications. We further discuss its extensions to discover the effect of single residue mutations, to model large protein assemblies, to improve its performance by exploiting conformational protein ensembles, and to reconstruct large PPI networks or pathway maps.

Operations Research Applications in Health Care Management

Reversible DNA codes using skew polynomial rings

In this study we determine the structure of reversible DNA codes obtained from skew cyclic codes. We show that the generators of such DNA codes enjoy some special properties. We study the structural properties of such family of codes and we also illustrate our results with examples.

Effects of Xylitol and Sucrose Mint Products on Streptococcus mutans Colonization in a Dental Simulator Model

Few laboratory methods exist for evaluating the cariogenicity of food ingredients. In this study, a dental simulator was used to determine the effects of commercial sucrose and xylitol mint products on the adherence and planktonic growth of Streptococcus mutans. Solutions (3% w/v) of sucrose, xylitol, sucrose mints, xylitol mints, xylitol with 0.02% peppermint oil (PO), and 0.02% PO alone were used to test the levels of planktonic and adhered S. mutans. A dental simulator with continuous artificial saliva flow, constant temperature, and mixing was used as a test environment and hydroxyapatite (HA) discs were implemented into the model to simulate the tooth surface. Bacterial content was quantified by qPCR. Compared with the artificial saliva alone, sucrose and sucrose mints increased the numbers of HA-attached S. mutans, whereas xylitol decreased them. Similarly, planktonic S. mutans quantities rose with sucrose and declined with xylitol and xylitol mints. Versus sucrose mints, xylitol mints significantly reduced the counts of HA-bound and planktonic S. mutans. Similar results were observed with the main ingredients of both types of mints separately. PO-supplemented artificial saliva did not influence the numbers of S. mutans that attached to HA or planktonic S. mutans compared with artificial saliva control. In our dental simulator model, xylitol reduced the counts of adhering and planktonic S.mutans. The mints behaved similarly as their pure, main ingredients-sucrose or xylitol, respectively. PO, which has been suggested to have antimicrobial properties, did not influence S. mutans colonization.

The effect of follicle size and homogeneity of follicular development on the morphokinetics of human embryos

Our aim was to investigate follicular size (large, ≥17 mm and small, <17 mm) at the time of OPU and homogeneity of follicular development (homogenous development: follicles being present in a homogenous spread of all sizes; heterogeneous: a predominance of small and large follicles) by analysing the morphokinetics of embryo development.

Tunable Plasmonic Silver Nanodomes for Surface-Enhanced Raman Scattering

Integration of risk matrix and event tree analysis: a natural stone plant case

Machining has considerably increased with evolving technology and increasing demand in natural stone production facilities. Different types of accidents may occur in natural stone facilities during movement, dimensioning, cutting of blocks and surface processing. These accidents may be due to physical, chemical, ergonomic and mechanical conditions. Therefore, possible work accidents and occupational diseases should be investigated. In this study, an L-matrix analysis is conducted to analyze hazards and forecast risks in natural stone facilities. According to the L-matrix results, three major initiating events are identified. For each of these initiating events, event tree analysis is used to calculate risk scores. These initiating events are hoist rope fatigue and breaking, diamond wire fatigue and breaking, and electrical leakage due to old systems. These events and their results are classified according to the probabilities using event tree analysis.

Experimental Cyclic Behavior of Precast Hybrid Beam-Column Connections with Welded Components

Post-earthquake observations revealed that seismic performance of beam-column connections in precast concrete structures affect the overall response extensively. Seismic design of precast reinforced concrete structures requires improved beam-column connections to transfer reversed load effects between structural elements. In Turkey, hybrid beam-column connections with welded components have been applied extensively in precast concrete industry for decades. Beam bottom longitudinal rebars are welded to beam end plates while top longitudinal rebars are placed to designated gaps in joint panels before casting of topping concrete in this type of connections. The paper presents the major findings of an experimental test programme including one monolithic and five precast hybrid half scale specimens representing interior beam-column connections of a moment frame of high ductility level. The required welding area between beam bottom longitudinal rebars and beam-end plates were calculated based on welding coefficients considered as a test parameter. It is observed that the maximum strain developed in the beam bottom flexural reinforcement plays an important role in the overall behavior of the connections. Two additional specimens which include unbonded lengths on the longitudinal rebars to reduce that strain demands were also tested. Strength, stiffness and energy dissipation characteristics of test specimens were investigated with respect to test variables. Seismic performances of test specimens were evaluated by obtaining damage indices.