Polymeric amylase nanoparticles as a new semi-synthetic enzyme system for hydrolysis of starch

α-Amylase (EC 3.2.1.1; α-d-1,4,glucan glucanohydrolase) catalyzes the hydrolysis of α-d-(1,4)-glucosidic linkages in starch, glycogen, and various malto-oligosaccharides, by releasing α-anomeric products. In this study, a novel method has been developed to prepare nanoprotein particles that carry α-amylase as a monomer by using a photosensitive microemulsion polymerization process. The nanostructured α-amylase with photosensitive features have been characterized by fluorescence spectroscopy, transmission electron microscopy (TEM) and Zeta Sizer. The fluorescence intensity of amylase nanoparticles was determined to be 658 a.u. at 610 nm and the average particle size of nanoamylase was found to be about 71.8 nm. Both free α-amylase and nanoparticles were used in the hydrolysis of starch under varying reaction conditions such as pH and temperature that affect enzyme activity and the results were compared to each other. K_m values were 0.26 and 0.87 mM and V_max values were 0.36 IU mg^? 1 and 22.32 IU mg^? 1 for nanoenzyme and free enzyme, respectively. Then, thermal stability, storage stability and reusability were investigated and according to the results, activity was preserved 60% at 60 °C; 20% at 70–80 °C temperature values and 80% after 105 days storage. Finally after 10 cycles, the activity was preserved 90% and this novel enzymatic polymeric amylase nanoparticle has showed considerable potential as reusable catalyst.     

Characterization of poly(vinylferrocenium) coated surfaces and their applications in DNA sensor technology

Poly(vinylferrocenium) (PVF⁺) modified gold (Au) electrode was developed in this study for the electrochemical sensing of deoxyribonucleic acid (DNA) hybridization based on the oxidation signals of polymer and guanine, and also for the electrochemical investigation of interaction of anticancer drug, mitomycin C (MC) and DNA immobilized onto PVF⁺ modified Au electrode. PVF⁺ modified Au electrode was prepared by electrooxidation of poly(vinylferrocene) PVF at +0.7 V versus Ag/AgCl reference electrode. The polymer modified electrode and DNA immobilized polymer modified electrode were characterized by X-ray photoelectron (XPS), Fourier transform infrared-attenuated total reflentance (FTIR-ATR) and alternating current (AC) impedance spectroscopy. For application studies, differential pulse voltammetry (DPV) technique was used.     

Use of Fenton oxidation to improve the biodegradability of a pharmaceutical wastewater

The applicability of Fenton's oxidation to improve the biodegradability of a pharmaceutical wastewater to be treated biologically was investigated. The wastewater was originated from a factory producing a variety of pharmaceutical chemicals. Treatability studies were conducted under laboratory conditions with all chemicals (having COD varying from 900 to 7000 mg/L) produced in the factory in order to determine the operational conditions to utilize in the full-scale treatment plant. Optimum pH was determined as 3.5 and 7.0 for the first (oxidation) and second stage (coagulation) of the Fenton process, respectively. For all chemicals, COD removal efficiency was highest when the molar ratio of H(2)O(2)/Fe(2+) was 150-250. At H(2)O(2)/Fe(2+) ratio of 155, 0.3M H(2)O(2) and 0.002 M Fe(2+), provided 45-65% COD removal. The wastewater treatment plant that employs Fenton oxidation followed by aerobic degradation in sequencing batch reactors (SBR), built after these treatability studies provided an overall COD removal efficiency of 98%, and compliance with the discharge limits. The efficiency of the Fenton's oxidation was around 45-50% and the efficiency in the SBR system which has two reactors each having a volume of 8m(3) and operated with a total cycle time of 1 day, was around 98%, regarding the COD removal.     

Poly(vinylbenzylchloride) beads grafted with polymer brushes carrying hydrazine ligand for reversible enzyme immobilization

Poly(glycidylmethacrylate), p(GMA), brush grafted poly(vinylbenzyl chloride/ethyleneglycol dimethacrylate), p(VBC/EGDMA), beads were prepared by suspension polymerization and the beads were grafted with poly(glycidyl methacrylate), p(GMA), via surface‐initiated atom transfer radical polymerization aiming to construct a material surface with fibrous polymer. The epoxy groups of the fibrous polymer were reacted with hydrazine (HDZ) to create affinity binding site on the support for adsorption of protein. The influence of pH, and initial invertase concentration on the immobilization capacity of the p(VBC/EGDMA‐g‐GMA)‐HDZ beads has been investigated. Maximum invertase immobilization onto hydrazine functionalized beads was found to be 86.7 mg/g at pH 4.0. The experimental equilibrium data obtained invertase adsorption onto p(VBC/EGDMA‐g‐GMA)‐HDZ affinity beads fitted well to the Langmuir isotherm model. It was shown that the relative activity of immobilized invertase was higher than that of the free enzyme over broader pH and temperature ranges. The K_m and V_max values of the immobilized invertase were larger than those of the free enzyme. After inactivation of enzyme, p(VBC/EGDMA‐g‐GMA)‐HDZ beads can be easily regenerated and reloaded with the enzyme for repeated use. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Prediction of earthquake damage to urban water distribution systems: a case study for Denizli,Turkey

Prediction of damage to water supply lines during an earthquake is a critical part of seismic planning. This study evaluates the performance of the water supply system in Denizli, Turkey, in the event of an M6, M6.3, M6.5 and M7 earthquake associated with the Pamukkale and Karakova-Akhan Faults. The relative effects of transient ground deformations and permanent ground deformations based on maps of liquefiable soil and zones of predicted lateral ground displacements are compared. The relative effects of the different magnitude earthquakes and pipeline damage relationships on the pipeline performance following a seismic event are assessed.     

Electrical conductivity changes of minced beef–fat blends during ohmic cooking

Minced beef–fat blends having different fat level (2%, 9% and 15%) and full meat-fat samples were ohmically cooked by different voltage gradients (20, 30 and 40 V/cm). Main factors affecting the electrical conductivity were the temperature and the composition of the blends. Although the effect of initial fat content on electrical conductivity was statistically significant, voltage gradient did not affect the electrical conductivity changes during cooking treatment (p > 0.05). The electrical conductivity of the samples increased with increasing temperature up to the critical initial cooking temperature (60–70 °C) depending on the fat level, and then decreased due to structural changes and the increase in the bound water during cooking. The results of the nonlinear mathematical model including the effects of initial fat level and the temperature on the electrical conductivity changes had good agreement (r = 0.952; SEM = 0.009) with the experimental data. The determination of electrical conductivity changes being affected by process variables is crucial to characterize the ohmic cooking of meat products and design of ohmic systems.     

Effects of ohmic thawing on histological and textural properties of beef cuts

The changes in the histology and the texture of beef cuts during ohmic thawing were compared with those during conventional thawing method. The beef cut samples were thawed from −18 to 10 °C by applying different voltage gradients (10, 20 and 30 V/cm) during ohmic treatment whereas conventional thawing was applied at constant temperature (25 °C, 95% RH) in the controlled incubator. There were significant differences between the effects of thawing methods in terms of hardness, chewiness, gumminess of beef cut samples (p < 0.05). The sample treated ohmically at 30 V/cm voltage gradient was significantly different from the other thawed samples in terms of springiness, cohesiveness and resilience (p < 0.05). The change in the textural properties was explained by investigating the histological changes of beef cuts for both thawing method. Ohmic thawing provided the thawed meat sample having lower textural and histological changes rather than conventionally thawed ones.     

Gain gradients applied to optimization of distributed‐parameter matching circuits for a microwave transistor subject to its potential performance

In this article, a rigorous design procedure is carried out for a microwave amplifier by employing the Feasible Design Space and simple analytical gain gradients of the matching circuits. Physical lengths and characteristic impedances of the transmission lines used in the matching circuits are chosen as the design variables and their lower and upper limits are bounded by the limits of the planar transmission line technology so that resulted microwave amplifier can be realized by this technology. Feasible Design Target Space is determined by the compatible performance [noise (F), input VSWR (V_i), gain (G_T)] triplets and their source Z_S(ω_i) and load Z_L(ω_i) terminations resulted from the performance characterization of the active device. These triplets take into account the physical limitations of the device and realization conditions so that F_req ≥ F_min, V_ireq ≥ 1, G_{T min} ≤ G_{T req} ≤ G_{T max}; and Z_S(ω_i) and Z_L(ω_i) terminations be taken place within the “Unconditionally Stable Working Area”. Design of the amplifier for the compatible performance triplets is reduced to the design of the Z_S(ω_i) and Z_L(ω_i), i = 1…N terminations, which is achieved by the gain optimization of the two passive, reciprocal matching two‐ports using the Darlington theorem. Analytical expressions of the gain gradients of the matching circuits are obtained by the two different methods: (i) chain sensitivity matrix approach; (ii) adjoint network approach. Gain gradients of the L‐, T‐, and Π‐types of distributed‐parameter matching circuits are obtained as worked examples. Then typical design examples are given with together the synthesized, target, simulated characteristics. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008.     

Rapid and Digital Detection of Inflammatory Biomarkers Enabled by a Novel Portable Nanoplasmonic Imager

New point‐of‐care diagnostic devices are urgently needed for rapid and accurate diagnosis, particularly in the management of life‐threatening infections and sepsis, where immediate treatment is key. Sepsis is a critical condition caused by systemic response to infection, with chances of survival drastically decreasing every hour. A novel portable biosensor based on nanoparticle‐enhanced digital plasmonic imaging is reported for rapid and sensitive detection of two sepsis‐related inflammatory biomarkers, procalcitonin (PCT) and C‐reactive protein (CRP) directly from blood serum. The device achieves outstanding limit of detection of 21.3 pg mL^?1 for PCT and 36 pg mL^?1 for CRP, and dynamic range of at least three orders of magnitude. The portable device is deployed at Vall d'Hebron University Hospital in Spain and tested with a wide range of patient samples with sepsis, noninfectious systemic inflammatory response syndrome (SIRS), and healthy subjects. The results are validated against ultimate clinical diagnosis and currently used immunoassays, and show that the device provides accurate and robust performance equivalent to gold‐standard laboratory tests. Importantly, the plasmonic imager can enable identification of PCT levels typical of sepsis and SIRS patients in less than 15 min. The compact and low‐cost device is a promising solution for assisting rapid and accurate on‐site sepsis diagnosis.     

Modelling of a new solar air heater through least-squares support vector machines

This paper reports on a modelling study of new solar air heater (SAH) system efficiency by using least-squares support vector machine (LS-SVM) method. In this study, a device for inserting an absorbing plate made of aluminium cans into the double-pass channel in a flat-plate SAH. A SAH system is a multi-variable system that is hard to model by conventional methods. As regards the LS-SVM, it has a superior capability for generalization, and this capability is independent on the dimensionality of the input data. In this study, a LS-SVM based method was intended to adopt SAH system for efficient modelling. For modelling, different mass flow rates in flow duct and collector types are used and then for obtaining the optimum LS-SVM parameters, such as regularization parameter, and optimum kernel function and parameters, several tests have been carried out. The performance of the proposed methodology was evaluated by using several statistical validation parameters. It is found that root mean squared error (RMSE) value is 0.0024, the coefficient of multiple determinations (R²) value is 0.9997 and coefficient of variation (cov) value is 2.1194 for the proposed radial basis function (RBF)-kernel LS-SVM method at 0.03 kg/s air mass flow rate. It is found that RMSE value is 0.0135, R² value is 0.9991 and cov value is 2.9868 for the proposed RBF-kernel LS-SVM method at 0.05 kg/s air mass flow rate. Comparison between predicted and experimental results indicates that the proposed LS-SVM model can be used for estimating the efficiency of SAHs with reasonable accuracy.