Modeling the Spill in the Songhua River after the Explosion in the Petrochemical Plant in Jilin

An explosion in a petrochemical plant in Jilin in the northeast of China on 13 November 13 2005 was responsible for the discharge of large quantities of benzene and nitrobenzene into Songhua River. This endangered the water supply of Harbin city and influenced the daily life for millions of people. The dispersion-advection equation was solved analytically and numerically and used to simulate the concentration of benzene and nitrobenzene in the Songhua River after the accident. Both solutions gave practically identical results. The main elimination process for both compounds was volatilization. The model results are quite close to the results obtained by measurements at monitoring stations. Arrival time of the pollutant wave, peak concentrations and end of the pollutant wave at Harbin and along the river were predicted successfully. The peak concentrations of nitrobenzene at Harbin were more than 30 times above the permissible limits for drinking water. This paper describes the distribution of benzene and nitrobenzene in the Songhua River after the accident in Jilin

Dynamic Fluid in a Porous Transducer-Based Angular Accelerometer

This paper presents a theoretical model of the dynamics of liquid flow in an angular accelerometer comprising a porous transducer in a circular tube of liquid. Wave speed and dynamic permeability of the transducer are considered to describe the relation between angular acceleration and the differential pressure on the transducer. The permeability and streaming potential coupling coefficient of the transducer are determined in the experiments, and special prototypes are utilized to validate the theoretical model in both the frequency and time domains. The model is applied to analyze the influence of structural parameters on the frequency response and the transient response of the fluidic system. It is shown that the radius of the circular tube and the wave speed affect the low frequency gain, as well as the bandwidth of the sensor. The hydrodynamic resistance of the transducer and the cross-section radius of the circular tube can be used to control the transient performance. The proposed model provides the basic techniques to achieve the optimization of the angular accelerometer together with the methodology to control the wave speed and the hydrodynamic resistance of the transducer

Characterization of Six Missense Mutations in the Tissue-Nonspecific Alkaline Phosphatase (TNSALP) Gene in Chinese Children with Hypophosphatasia

Aims: Hypophosphatasia, a rare inherited disease characterized by defective mineralization of bone and teeth, is caused by various mutations in the tissue-nonspecific isoenzyme of alkaline phosphatase (TNSALP) gene. Our aim was to determine the mutations on TNSALP gene in three Chinese children diagnosed as having hypophosphatasia. Methods: Genomic DNA was extracted from whole blood samples of patients and their parents. The TNSALP coding regions were then sequenced. Plasmids expressing wild-type or various mutants were built and in vitro studies were performed in order to determine whether these amino acid replacements could affect the TNSALP enzymatic activity. Results: Six missense mutations were identified from three independent pedigrees. Of the six missense mutations, four were novel and two had been previously reported. The Y28D, A111T and T389N mutants displayed only negligible ALP activity in vitro compared to the wild-type (WT) TNSALP. The defect was mainly due to the significantly decreased protein expression in the 66 KD immature forms and the nearly undetectable protein expression in the 80 KD mature forms. Moreover, all three mutants had a dominant negative effect on the WT protein when co-transfected with TNSALP (WT). M219V and R136L mutants both exhibited partial enzymatic activities which were consistent with reduced protein expression in both forms of TNSALP which further exhibited moderate dominant-negative effect. In addition, Y388H mutant showed weak ALP activity. Western blot analysis indicated that the extreme reduction in signal from the mature forms of TNSALP could be the main cause of decreased enzymatic activity, since a strong signal was observed in the immature forms. Conclusion: Six missense mutations were identified in three Chinese hypophosphatasia pedigrees with subnormal serum ALP activity. Our results show that the low activity of serum ALP in the three patients is due mainly to a defect in the protein expression of the mutants. This may be the underling molecular mechanism for hypophosphatasia in these patients