OBJECTIVE: To investigate the sensing volume of open-ended coaxial probe technique for measurement of dielectric characteristics. METHODS: A measurement model combining macro- measurement device with a layer model of dielectric properties parameters was established for evaluating the sensing volume of open-ended coaxial probe technique. We defined sensing depth and sensing diameter to describe the distance that could be detected in vertical and horizontal direction. Using a variety of materials with different dielectric properties (Teflon, deionized water, ethanol, and gradient concentration sodium chloride solution), a layered model of dielectric properties differentiation was established. The total combined uncertainties (TCU) were calculated for different output power, and the output power was controlled to increase from -50 dBm to 15 dBm to calibrate the error range of the dielectric properties measurement system. The optimal output power range was determined based on the results of TCU test. In sensing volume measurement experiment, we set the control groups based on measurement parameters that potentially affect the sensing volume including output power (-10, -5, 0, 3, 6, and 9 dBm), frequency (1-500 MHz), Teflon, deionized water, and ethanol to form a dielectric constant difference between high and low contrast groups. Different concentrations of sodium chloride solution and Teflon were used to generate a conductivity difference between high and low contrast groups. These groups were tested in the sensing depth and sensing diameter measurement experiments. RESULTS: The result of TCU test indicated that accurate and stable measurement results could be obtained when the output power was greater or equal to-10 dBm (TCU < 2%). Sensing volume measurement experiment revealed a positive correlation between the sensing depth and output power ( < 0.05). As the measured power increased, the sensing depth gradually increased in deionized water and ethanol, and the difference reached 70 μm. The sensing depth was negatively correlated frequency ( < 0.05). As the concentration of sodium chloride solution increased, the corresponding sensing depth gradually decreased, with a difference reaching 270 μm. The sensing depth of high dielectric materials was greater than that pf low dielectric materials. The results of sensing diameter measurement were not obviously affected by the measurement parameters, and the sensing diameter was stable in a fixed range (1.0 to 1.8 mm) between the diameter of the inner conductor and the diameter of the insulation layer, and was less than the diameter of the probe. CONCLUSIONS The sensing volume of open-ended coaxial probe technique is affected by measurement parameters and dielectric properties of materials, which significantly affect the sensing depth.
Algorithms ; Electric Conductivity ; Electrochemistry ; instrumentation

Three-electrode testing method was used to investigate the effect of temperature on electrode impedance, and the pH shifts in saline solution resulting from the electrical stimulation were also determined. Experiments in PBS (phosphate buffered solution) solution showed that the electrode impedance was almost invariable at the human body temperature range (35 degrees C-40 degrees C). And the experiments in unbuffered saline solution showed that pH shifts decreased from 0.03 to 0.005 when the frequency of biphasic charged-balanced pulses increased from 1 Hz to 100 Hz. Even stimulated by monophasic pulses (frequency is 15 Hz, amplitude is 50 microA), the stimulus-induced pH shift of electrode only varies 0.15 (anodic pulse current increased 0.15 and cathodic pulse current decreased 0.15).
Electrochemistry ; Eye, Artificial ; Materials Testing ; Microelectrodes ; Prostheses and Implants

Tissue engineering technology provides a new method to repair ill tissue and worn-out organs. In tissue engineering, scaffolds play an important role in supporting cell growth, inducing tissue regeneration, controlling tissue structure and releasing active factor. In the last decade, electrospinning technology developed rapidly and opened vast application fields for scaffolds. In this review, we summarized the technological conditions of electrospinning for scaffolds, the study of electrospun fiber scaffolds applied in tissue cell cultivation, and some new directions of electrospinning technology for scaffolds. We also addressed development directions of electrospinning research for scaffolds.
Absorbable Implants ; Biocompatible Materials ; chemistry ; Electrochemistry ; methods ; Guided Tissue Regeneration ; Tissue Engineering ; instrumentation ; methods ; Tissue Scaffolds ; chemistry

In order to summarize and analyze the progresses and problems of resistance testing and technology research on acupoints, investigate the related solutions, articles on resistance testing from 1990 to 2011 were collected, and advantages and shortcomings of different types of testing instruments were discussed in this article as well. Detection technology of acupoint impedance has under updating changes, which are often applied on locating acupoints and clinical diagnosis. The progresses of those technologies are mainly embodied in improvement of circuit model, which enable a longer testing duration, less media interference and so on. The previous studies often focus on resistance testing of the skin. Since dermal resistance does not equal to acupoint resistance, the designation of equivalent circuit does not embody the condition of cells, tissues and nerves at acupoints, and testing technology is often affected by factors such as polarization of electrodes, contact medium and anatomical characteristics of acupoints, the resistance of acupoints can not be taken as the effective framework of the diagnostic standard and judgement of therapeutic effect in clinic. Based on the key problems in resistance testing of acupoints, it is proposed by the article that the techniques and designation of circuit model should be reformed, and mathematical model should be established in the study to meet the requirement of the life system. Inductance of human body should be considered in resistance research of acupoints, and interference factors should be eliminate as far as possible in designation of equipments. Thus, the change law of acupoint resistance in the inner part of the body can be fully embodied by the designation of experiments.
Acupuncture Points ; Chemical Phenomena ; Electric Impedance ; Electrochemistry ; instrumentation ; Humans ; Meridians ; Skin ; chemistry

In this study, based on the correlation between the blood and saliva glucose, we proposed and developed a new conceptual method of using mobile phone to measure wirelessly the glucose concentration in saliva. According to the experiments on simulated saliva, the new system could draw, display, store and carry out calculation on the correlation curves between saliva glucose and electrical parameters. This demonstrates the feasibility and bright future of the new technique.
Cell Phone ; Electrochemistry ; methods ; Glucose ; analysis ; Humans ; Saliva ; chemistry ; Wireless Technology

OBJECTIVEThe aim of this study was to investigate the korrosionsneigung of three metal specimens for casing removable denture by means of electrochemical method.

METHODSThree kinds of test specimens were prepared, including cobalt-chromium alloy, nickel-chrome alloy with titanium and pure titanium. Then they were analyzed via linear polarization in artificial saliva simulating oral environment. From this electrochemical test the polarization curves of these kinds of specimens were recorded. Then the scanning electron microscope (SEM) and X-ray diffractometer (XRD) were applied to assess the morphology and phase changes before and after electrochemical corrosion.

RESULTSNo typical Tafel curve had been recorded for pure titanium, other than cobalt-chromium alloy and nickel-chrome alloy with titanium. Nickel-chrome alloy with titanium got more negative corrosion potential and higher corrosion current than cobalt-chromium alloy. Via SEM, the obvious changes were observed on the morphology and phase before and after corrosion on cobalt-chromium and nickel-chrome alloy with titanium specimens while pure titanium having no change. The XRD provided us little changes on these all three materials.

CONCLUSIONThe results confirm that the korrosionsneigung of the studied cobalt-chromium alloy in artificial saliva is lower than that nickel-chrome alloy with titanium. Pure titanium is the most stable one of the three materials and is extreme hard to be etched.

Chromium ; Chromium Alloys ; Corrosion ; Dental Alloys ; Electrochemistry ; Nickel ; Titanium

A novel type of carbon nanotube-coated Au nanoparticle and [bmim]BF4 composite modified glassy carbon electrode was fabricated by a layer-by-layer self-assembly technique. The electrochemical performance of acetaminophen (ACOP) on the modified electrode was investigated by cyclic voltammetry. The Nafion/GNPs/RTIL/MWNTs/GC electrode showed an excellent electrocatalytic activity for the oxidation of ACOP and accelerated electron transfer between the electrode and ACOP. For ACOP, the reversible electrochemical process was observed on the Nafion/GNPs/RTIL/MWNTs/GC electrode, while irreversible electrochemical process occurred on the GC electrode. For the Nafion/GNPs/RTIL/MWNTs/GC electrode, the anodic peak potential of ACOP was moved from 0.562 V to 0.413 V, with a potential drop of 149 mV. At the same time, the reduction peak potential was 0.384 V, and the potential difference was only 29 mV. It was shown that the modified electrode possessed higher electrocatalytic activity and more sensitive effect for the detection of ACOP than both MWNTs/GC electrode and GC electrode. The effects of the different experimental conditions on the electrochemical behaviors of ACOP were explored. Under the optimum conditions of preparation and experimental, the linear calibration curves of ACOP were obtained in a wide range of 2 x 10(-1) to 4.0 x 10(-4) mol x L(-1) with a correlation coefficient 0.999 2 and a detection limit of 2.6 x 10(-8) mol x L(-1) (the ratio of signal to noise, 3:1). The recovery rate was 97.9%-100.8%. This method can be used to determine ACOP in paracetamol tablets with satisfactory results.
Acetaminophen ; analysis ; Analgesics, Non-Narcotic ; analysis ; Antipyretics ; analysis ; Electrochemical Techniques ; methods ; Electrochemistry ; methods ; Electrodes ; Electron Transport ; Gold ; chemistry ; Nanotubes, Carbon ; chemistry ; Oxidation-Reduction ; Reproducibility of Results

OBJECTIVETo establish the quality criteria for decoction pieces of salt Alpinia.

METHODDecoction pieces of salt Alpinia were measured with moisture, total ash, acid-insoluble ash, water-extract and volatile oils according to the procedures recorded in the Chinese Pharmacopoeia 2010. The content of Nootkatone was determined by HPLC, and NaCl, by chloridion electrode method.

RESULTWe obtained results of total ash, acid-insoluble ash, water-extract and volatile oils of 10 batches of decoction pieces of salt Alpinia moisture; Meanwhile we set the HPLC and chloridion electrode method.

CONCLUSIONThis research established a fine quality standard for decoction pieces of salt Alpinia.

Alpinia ; chemistry ; Calibration ; Chromatography, High Pressure Liquid ; Electrochemistry ; Oils, Volatile ; analysis ; Quality Control ; Salts ; chemistry ; Solubility ; Water ; chemistry

Electrospinning is a very effective way to prepare scaffolds for biomedical applications. However, conventional electrospinning technique has shortcomings for this purpose. Modification studies on electrospinning technique have been conducted by more and more researchers. This paper summaries the research progress in electrospinning technique for biomedical materials.
Biocompatible Materials ; chemical synthesis ; Elasticity ; Electrochemistry ; instrumentation ; methods ; Materials Testing ; Nanostructures ; chemistry ; Tissue Engineering ; methods ; Tissue Scaffolds ; chemistry

OBJECTIVETo study the effect on the corrosion resistance of Cr alloy in the artificial saliva with different pH value in vitro.

METHODSCompared to Ti alloy, electrochemical technique was used to measure the electric potential of corrosion (E(corr)), current density of corrosion (I(corr)) Cr alloy in the artificial saliva with different pH value. The corrosion and corrosion resistance mechanism on Cr alloy in the artificial saliva with different pH value had been investigated by the EIS curves.

RESULTSThe corrosion resistance of Co-Cr alloy was better than Ti alloy. The value of I(corr) was lower and the value of R(p) was larger than Ti alloy. The corrosion resistance of Ni-Cr alloy was worse than Ti alloy. The value of I(corr) was larger and the value of R(p) was lower than Ti alloy. The pH value in the artificial saliva was decreased, the I(corr) value of three types of alloy increased, the R(p) value of three types of alloy decreased. But the changes of Co-Cr alloy was smaller than that of Ti alloy or Ni-Cr alloy.

CONCLUSIONThe corrosion resistance of Co-Cr alloy was superior to that of Ni-Cr alloy and Ti alloy. In the acid artificial saliva, the corrosion resistance of three types of alloy descended evidently.

Corrosion ; Dental Alloys ; Electrochemistry ; Saliva, Artificial ; Surface Properties ; Titanium