Cost-effective disposable thiourea film modified copper electrode for capacitive immunosensor

Cost-effective disposable electrodes were fabricated from copper clad laminate, usually used for printed circuit board (PCB) in electronic industries, by using dry film photoresist. Electro-oxidation (anodisation) was employed to obtain a good formation of thiourea film on the electrode surface. The affinity binding pair of carcinoembryonic antigen (CEA) and anti-carcinoembryonic antigen (anti-CEA) was used as a model system. Anti-CEA was immobilized on thiourea film via covalent coupling. This modified electrode was incorporated with a capacitive system for CEA analysis. This capacitive immunosensor provided a linear range between 0.01 and 10 ng ml⁻¹ with a detection limit of 10 pg ml⁻¹. When applied to analyze CEA in serum samples, the results agreed well with the enzyme linked fluorescent assay (ELFA) technique (P > 0.05). The proposed strategy for the preparation of disposable modified copper electrode is very cost effective and simple. Moreover, it provides good reproducibility. This technique can easily be applied to immobilize other biological sensing elements for biosensors development.     

A fast tag identification anti‐collision algorithm for RFID systems

In this work, we propose a highly efficient binary tree‐based anti‐collision algorithm for radio frequency identification (RFID) tag identification. The proposed binary splitting modified dynamic tree (BS‐MDT) algorithm employs a binary splitting tree to achieve accurate tag estimation and a modified dynamic tree algorithm for rapid tag identification. We mathematically evaluate the performance of the BS‐MDT algorithm in terms of the system efficiency and the time system efficiency based on the ISO/IEC 18000‐6 Type B standard. The derived mathematical model is validated using computer simulations. Numerical results show that the proposed BS‐MDT algorithm can provide the system efficiency of 46% and time system efficiency of 74%, outperforming all other well‐performed algorithms.     

Suction-Monitored Direct Shear Testing of Residual Soils from Landslide-Prone Areas

The apparent cohesion due to soil suction plays an important role in maintaining the stability of steep unsaturated soil slopes with deep ground water table. In this paper, a modified direct shear box is used to determine the relationships between the value of this additional cohesion and the associated soil suction. The apparatus incorporates a miniature tensiometer which allows for the simple and direct measurement of suction during shearing. The soil-water characteristic curves and shearing behavior of intact residual soils, being low-to-medium plasticity silts, as well as silty sand, taken from four landslide-prone areas in Thailand, have been investigated. The relatively low air-entry suctions (0–7 kPa) and bimodality of the soil-water characteristic curves gives an indication of the structured pore size distribution of the materials tested. Samples with higher suction tend to display stronger bonding at particle contacts and thus are more brittle. The shear strength is found to increase nonlinearly with suction, though linearization can be reasonably assumed for suction below around 30 kPa. Prediction of shear strength based on soil-water characteristic curves agrees better with ultimate than peak values. A simple equation is proposed for the minimum ultimate strength that can be expected in an unsaturated residual soil with a suction lower than about 30 kPa.     

Analysis of raw microneurographic recordings based on wavelet de-noising technique and classification algorithm: wavelet analysis in microneurography

We propose a new technique for analyzing the raw neurogram which enables the study of the discharge behavior of individual and group neurons. It utilizes an ideal bandpass filter, a modified wavelet de-noising procedure, an action potential detector, and a waveform classifier. We validated our approach with both simulated data generated from muscle sympathetic neurograms sampled at high rates in five healthy subjects and data recorded from seven healthy subjects during lower body negative pressure suction. The modified wavelet method was superior to the classical discriminator method and the regular wavelet de-noising procedure when applied to simulated neuronal signals. The detected spike rate and spike amplitude rate of the action potentials correlated strongly with number of bursts detected in the integrated neurogram (r = 0.79 and 0.89, respectively, p < 0.001). Eight major action potential waveform classes were found to describe more than 81% of all detected action potentials in all subjects. One class had characteristics similar in shape and in average discharge frequency (27.4 +/- 5.1 spikes/min during resting supine position) to those of reported single vasoconstrictor units. The newly proposed technique allows a precise estimate of sympathetic nerve activity and characterization of individual action potentials in multiunit records.