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An electroanalytical method for the determination of ammonium ion using a platinized platinum electrode is described. Under optimized analytical conditions, the linear range of the calibration graphs for ammonium ion is 3.0×10−5−5.0×10−3 mol·L−1 with a detection limit of 5.0×10−6 mol·L−1. The method has been applied to the determination of ammonium ion in lake water samples and recoveries of 100%–103% are obtained. The results obtained are found to be in good agreement with spectrophotometric results.

Superoxide ion was generated by the electrochemical reduction of oxygen at a platinum electrode in dimethylsulphoxide (DMSO). This work was focused on the nucleophilicity and scavenge of electrogenerated-superoxide ion by cyclic voltammetry. The nucleophilic displacement reactions of superoxide ion with ethyl acetate and diethyl adipate were discussed and the reason for remarkable influence of diethyl adipate was elucidated. The scavenging activity of ascorbic acid was evaluated and the result allowed the conclusion that the scavenging ability of ascorbic acid is much lower in DMSO than in aqueous phase. UV-spectrum of electrogenerated superoxide ion in DMSO exhibited a single absorption band with λmax at 275 nm, which certified further that the method of electrogeneration was reliable and superoxide ion was stable in DMSO.

In this study, a method based on wavelet transforms (WT) and Mann-Kendall (M-K) test for the runoff series multi-scale analysis in Yulin area is proposed. The result shows that, the runoff exhibits a statistically significant decreasing trend during the last five decades at the level of α=0.05, the Z value of the M-K test gets significantly decreased, what's more, a significant decreasing tendency started at the early of 1980s; the periodicities locates at 16-year and 29-year scale level are seen during for each continuous spectrum, the major periodicity is located at 16-year scale level, and it can forecast that Yulin exists in low-flow period; we use discrete wavelet (DW) transform coefficients at each decomposition level for non-parametric trend test. It indicates that DW1+DW2+DW4+DW5+approximation has resulted to be the nearest to the real M-K trend values.

Image enhancement based dim target extraction techniques are proposed. Firstly, the dim targets are enhanced through an improved retinex (MLIP_MSR) method which combines the multi-scale retinex (MSR) algorithm and the modified logarithmic image processing (LIP) model. Secondly, the targets are roughly obtained by applying the relaxation iterative segmentation algorithm (RIS), while part background is also retained, then the background filtering is used to remove the remained background. Finally the canny operator is applied to get the contour of the final dim targets and add it to the original image. Because of the MLIP_MSR enhancement, RIS can efficiently segment the dim infrared image. Experimental results verified the effective performance of the proposed method.

Phase retrieval problem has attracted many interests for its wide application in many domains. In this paper we focus on the topic of retrieving the full complex wave field of the object plane from three or more diffraction planes. The iterative Fresnel algorithm always suffers from slow convergence and stagnation problems, while the generalized hybrid-input-output (GHIO) algorithm can effectively accelerate convergence and break stagnation of this kind. Therefore, we combined the two methods into a more efficient algorithm. Each step, the iterative Fresnel algorithm using three or more diffraction intensities is firstly performed to jointly estimate the intensity and the phase of the object plane. Then the GHIO algorithm is adopted to generate a new complex amplitude for the next iteration. It is not necessary to search optimal step size as the conjugate gradient method and can also avoid stagnation, so it is very efficient. This is proved by simulations. intensities should be explored. Many authors have devoted to studying this topic(13-17). The mainly proposed algorithms are based on the conjugate gradient method. It needs to search optimal step size, so although these kinds of algorithms have been proved effective by experiments (15-17), they always have to spend much time to achieve an acceptable result. A more efficient algorithm, in which the iterative Fresnel algorithm and the GHIO algorithm are combined to retrieve the complex wave field, is proposed in the present paper. The GHIO algorithm is used to avoid stagnation and speed up the convergence of the iterative Fresnel algorithm. We show by simulations that this algorithm is more efficient than the method introduce in (16).

AIM: To explore the influence of portal vein hemo-dynamic changes after portal venous arterialization (PVA) on peribiliary vascular plexus (PVP) morphological structure and hepatic pathology, and to establish a theoretical basis for the clinical application of PVA. METHODS: Sprague-Dawley rats were randomly divided into control and PVA groups. After PVA, hemodynamic changes of the portal vein and morphological structure of hepatohilar PVP were observed using Doppler ultrasound, liver function tests, ink perfusion transparency management and three-dimensional reconstruction of computer microvisualization, and pathological examination was performed on tissue from the bile duct wall and the liver. RESULTS: After PVA, the cross-sectional area and blood flow of the portal vein were increased, and the increase became more significant over time, in a certain range. If the measure to limit the flow in PVA was not adopted, the high blood flow would lead to dilatation of intrahepatic portal vein and its branches, increase in collagen and fiber degeneration in tunica intima. Except glutamic pyruvic transaminase (GPT), other liver function tests were normal. CONCLUSION: Blood with a certain flow and oxygen content is important for filling the PVP and meeting the oxygen requirement of the bile duct wall. After PVA, It is the anatomic basis to maintain normal morphology of hepatohilar bile duct wall that the blood with high oxygen content and high flow in arterialized portal vein may fill PVP by collateral vessel reflux. A adequate measure to limit blood flow is necessary in PVA.

A variational model which is used to locate at the boundary of the object in the designated region is presented in this paper. This is done by adding an intersect area term into our model, which will play an important role in this paper. In this model, we need to construct an energy functional e using two level set functions. One is used to capture the object of interest, the other one indicates image region which should be corrected. By minimizing the proposed model with respected to both two functions,the approach permits to segment the more accurate boundary. We implement our model with two algorithms, advantages and disadvantages of the two algorithms are discussed according to the experiment result. At the same time, we compare our model with a model proposed by Chunming Li et al. The result shows that our model is more accurate.