Effect of muscle stretching on meat quality of biceps femoris from beef

The objective of this study was to examine the effect of muscle stretching on meat quality and ultrastructure of biceps femoris (BF) from beef. After slaughter, the right side of the carcasses were suspended from the Achilles tendon (AS; n=10), while the left sides were re-hanged from the pelvic bone (PS; n=10). Meat quality was evaluated by water holding capacity (WHC), cooking loss (CL), color, shear force (SF) and sarcomere length (SL). As a result, PS had no impact on WHC, CL and color parameters. PS significantly decreased SF values by 7.5% only at 2 days postmortem. At pelvic suspended sides, SL was increased by 0.13 μm, 0.14 μm and 0.12 μm at 2, 7 and 10 days postmortem, respectively (P<0.001). Electron microscopy showed that the ultrastructure of BF have longer sarcomeres and smaller fiber diameter after PS. In conclusion, PS is a useful method for improving tenderness by stretching muscles.     

Evaluation of L929 fibroblast attachment and proliferation on Arg-Gly-Asp-Ser (RGDS)-immobilized chitosan in serum-containing/serum-free cultures

In this study, chitosan membranes prepared by the solvent casting method were modified with the Arg-Gly-Asp-Ser (RGDS) sequence of fibronectin using the photochemical immobilization technique. The results obtained from attenuated total reflection-Fourier transform infrared spectra and X-ray photoelectron spectroscopy studies confirmed the successful immobilization of RGDS on chitosan membranes. The immobilized peptide concentration was determined by ninhydrin analysis on the order of 10(-7) mol/cm(2). In vitro cell culture studies were performed with L929 mouse fibroblasts to investigate the effect of biomodification on fibroblast cell behaviour in serum-free and 10% serum-containing media. The results obtained from cell culture studies pointed out the specific interactions between biosignal RGDS molecules and fibroblast cells. A triggered cell attachment and proliferation were observed on RGDS-modified chitosan membranes that were more distinguishable in serum-free medium. In addition, the photochemical immobilization technique was realized in the presence of a photomask that was used to immobilize the RGDS molecules in a defined micropattern. L929 mouse fibroblasts attached on the RGDS-micropatterned areas indicating integrin-mediated interactions.     

Deposition and Characterization of Tungsten Carbide Thin Films by DC Magnetron Sputtering for Wear-Resistant Applications

In this study, WC (tungsten carbide) thin films were deposited on high-speed steel (AISI M2) and Si (100) substrates by direct current magnetron sputtering of a tungsten carbide target having 7% cobalt as binding material. The properties of the coatings have been modified by the change in the bias voltages from grounded to 200 V. All the coatings were deposited at 250°C constant temperature. The microstructure and the thickness of the films were determined from cross-sectional field-emission gun scanning electron microscope micrographs. The chemical composition of the film was determined by electron probe micro analyzer. The x-ray diffractometer has been used for the phase analyses. Nanoindentation and wear tests were used to determine the mechanical and tribological properties of the films, respectively. It is found that the increase in the bias voltages increased drastically the hardness and elastic modulus, decreased the friction coefficient values and increased the wear resistance of tungsten carbide thin films by a phase transformation from metallic W (tungsten) to a nonstoichiometric WC_1?x (tungsten carbide) phase.     

Electrolyte type and concentration effects on poly(3-(2- aminoethyl thiophene) electro-coated on glassy carbon electrode via impedimetric study

In this study, 3-(2-Aminoethyl thiophene) (2AET) monomer was electropolymerized on glassy carbon electrode (GCE) using various electrolytes (lithium perchlorate (LiClO₄), sodium perchlorate (NaClO₄), tetrabutyl ammonium tetra fluoroborate (TBABF₄) and tetraethyl ammonium tetra fluoroborate (TEABF₄) in acetonitrile (CH₃CN) as solvent. Poly(3-(2-aminoethyl thiophene) (P(2AET))/GCE was characterized by cyclic voltammetry (CV), Fourier transform infrared reflectance spectrophotometry (FTIR-ATR), scanning electron microscopy, energy dispersive X-ray analysis (EDX), and electrochemical impedance spectroscopy (EIS) techniques. The electrochemical impedance spectroscopic results were given by Nyquist, Bode-magnitude, Bode-phase, capacitance and admittance plots. The highest low frequency capacitance (C _LF) value obtained was 0.65 mF cm^?2 in 0.1 M LiClO₄/CH₃CN for the initial monomer concentration of 1.5 mM. The highest double layer capacitance (C _dl = ~0.63 mF cm^?2) was obtained in 0.1 M LiClO₄/ACN for [2AET]₀ = 0.5, 1.0 and 1.5 mM. The maximum phase angles (θ = 76.1^o at 26.57 Hz) and conductivity (Y″ = 3.5 mS) were obtained in TEABF₄/ACN for [2AET]₀ = 0.5 and 1.0 mM, respectively. An equivalent circuit model of R(Q(R(Q(R(CR))))) was simulated for different electrolytes (LiClO₄, NaClO₄, TBABF₄ and TEABF₄)/P(2AET)/GCE system. A good fitting was obtained for the calculated experimental and theoretical EIS measurement results. The electroactivity of P(2AET)/GCE opens the possibility of using modified coated electrodes for electrochemical micro-capacitor electrodes and biosensor applications.     

A Photoluminescent Polymeric 2D Silver(I) Complex Exhibits a Fishbone-like 1D Silver Cluster and New Coordination Mode of the Pyridine-2,3-Dicarboxylate

In this study, a novel organic–inorganic hybrid compound with AgNO₃ and 2,3-pyridinedicarboxylic acid (H₂pydc), [Ag₂(μ₆-pydc)]_n (1) has been synthesized. The molecular structure of complex has been determined by the single crystal X-ray diffraction. The complex has been observed to crystallize in the monoclinic space group P2₁/c. The asymmetric unit of compound consists of two crystallographically different Ag(I) centers and one pydc ligand. The Ag1 and Ag2 adopt tetrahedral and T-shaped geometries, respectively. At the same time, the silver(I) compound consists of a fish bone similar to the 1D silver cluster. Furthermore, novel coordination mode shown by H₂pydc indicates that the crystal exhibits photoluminescence in the solid state at room temperature.     

Statistically reliable and fast direct estimation of phase-amplitude cross-frequency coupling

There is growing interest in phase-amplitude cross-frequency coupling (PAC), which is widely observed in human and animal brain recordings. The choice of the estimation method is vital while extracting accurate PAC parameters from data. Two desired properties of PAC estimators are reliability and computational efficiency. This study offers a methodology called normalized direct PAC (ndPAC) for the rapid and statistically reliable estimation of PAC strength. A plain confidence limit formula, depending solely on data length and confidence level, is derived. Confidence level derivation is validated numerically. It is shown through simulations that ndPAC exhibits high specificity and sensitivity performances. The suggested methodology is also demonstrated on monkey electrocorticogram recorded during a visual task.     

Assessment of extensive countrywide electrical power quality measurements through a database architecture

This paper describes countrywide electrical power quality (PQ) assessments of the Turkish Electricity Transmission System through a genuine PQ database. The database stores the output of mobile PQ measurement systems which are established at 172 transformer substations of the transmission system. At 601 measurement points in these substations, which are potentially critical in terms of PQ, measurements are carried out by the mobile systems for a period of 1 week. PQ parameters defined in the IEC-61000-4-30 standard in addition to power values are calculated from acquired raw data by the mobile-monitoring system and the resulting data are transferred to the PQ database. The database, based on a novel PQ data model, enables its users to take PQ snapshots of the transmission system countrywide and can be accessed through several interfaces including a visual query interface, a natural language interface, and a map interface. The overall PQ status of the measured points, representing the characteristics of the transmission system, is assessed through these interfaces and problematic points are determined while deriving important conclusions about the transmission system’s PQ behavior. Moreover, several novel PQ assessment methods are proposed and their applications on the PQ data are demonstrated especially through the map interface.     

Potential methods for geothermal-based hydrogen production

In this study, four potential methods are identified for geothermal-based hydrogen production, namely, (i) directly from the geothermal steam, (ii) through conventional water electrolysis using the electricity generated from geothermal power plant, (iii) using both geothermal heat and electricity for high temperature steam electrolysis and/or hybrid processes, (iv) using the heat available from geothermal resource in thermochemical processes to disassociate water into hydrogen and oxygen. Here we focus on relatively low-temperature thermochemical and hybrid cycles, due to their greater application possibility, and examine them as a potential option for hydrogen production using geothermal heat. We also present a brief thermodynamic analysis to assess their performance through energy and exergy efficiencies for comparison purposes. The results show that these cycles have good potential and become attractive due to the overall system efficiencies over 50%. The copper–chlorine cycle is identified as a highly promising cycle for geothermal hydrogen production. Furthermore, three types of industrial electrolysis methods, which are generally considered for hydrogen production currently, are also discussed and compared with the above mentioned cycles.     

Energy and exergy analyses of a new four-step copper–chlorine cycle for geothermal-based hydrogen production

In this paper, energy and exergy analyses of the geothermal-based hydrogen production via thermochemical water decomposition using a new, four-step copper–chlorine (Cu–Cl) cycle are conducted, and the respective cycle energy and exergy efficiencies are examined. Also, a parametric study is performed to investigate how each step of the cycle and its overall cycle performance are affected by reference environment temperatures, reaction temperatures, as well as energy efficiency of the geothermal power plant itself. As a result, overall energy and exergy efficiencies of the cycle are found to be 21.67% and 19.35%, respectively, for a reference case.