Showing papers by "Wuhan University published in 2004"

Focusing of sound in a 3D phononic crystal.

Abstract: We present a combined experimental and theoretical study of phonon focusing phenomena in a pass band above the complete band gap in a 3D phononic crystal Wave propagation was found to depend dramatically on both frequency and incident direction This propagation anisotropy leads to very large negative refraction, which can be used to focus a diverging ultrasonic beam into a narrow focal spot with a large focal depth The experimental field patterns are well explained using a Fourier imaging technique, based on the 3D equifrequency surfaces calculated from multiple scattering theory

Water problems and hydrological research in the Yellow River and the Huai and Hai River basins of China

Abstract: This paper deals with hydrological research in regard to the water resources crisis in the vulnerable areas found in the northern part of China. This area includes three main river basins, namely the basins of the Yellow (Huang) River, the Hai River and the Huai River. Several water problems are becoming very severe. Among them, two are the most critical: the Yellow River has been drained dry in the main course of its lower reaches and along its major tributaries, and the groundwater table has rapidly declined in the floodplains of the three rivers' downstream areas. To counter the problems, particularly the critical issues mentioned above, hydrological research, which serves as the basis of water development and management, has been carried out in the last two decades. This paper addresses three basic scientific problems in North China, namely: (a) water consumption and the capacity for saving water; (b) the changes in hydrological processes and water resources caused by natural change and human activities; and (c) the ability to supply water resources and water safety in terms of both quantity and quality within a changing environment. However, opportunities and challenges for ameliorating the problems exist, and new ideas and methodology to solve the problems have been proposed, such as the interface process study on the interactions in the soil-root interface, the plant-atmosphere interface, the soil-atmosphere interface, and the interface of soil water and groundwater. In order to manage water resources in a sustainable manner, the study of water resources' renewal ability as affected by natural change and human activity is addressed from the viewpoint of both water quantity and quality, and their integration. To reduce the vulnerability of water resources in regional water management, a paradigm of sustainable water resources utilization is also proposed, using water-heat balance, water-salt balance, water-sediment balance, and water supply-demand balance. This approach may help reveal the basic problems and point to possible approaches to solving the water problems in North China in the 21st century. Copyright (C) 2004 John Wiley Sons

Quaternary Aquifer of the North China Plain—assessing and achieving groundwater resource sustainability

Abstract: The Quaternary Aquifer of the North China Plain is one of the world’s largest aquifer systems and supports an enormous exploitation of groundwater, which has reaped large socio-economic benefits in terms of grain production, farming employment and rural poverty alleviation, together with urban and industrial water-supply provision. Both population and economic activity have grown markedly in the past 25 years. Much of this has been heavily dependent upon groundwater resource development, which has encountered increasing difficulties in recent years primarily as a result of aquifer depletion and related phenomena. This paper focuses upon the hydrogeologic and socio-economic diagnosis of these groundwater resource issues, and identifies strategies to improve groundwater resource sustainability.

Surface plasmon polariton propagation in nanoscale metal gap waveguides.

Abstract: Based on finite-difference time-domain simulation of the propagation characteristics of surface plasmon polaritons (SPPs) in optical circuits made from metal gap waveguides (MGWs) with nanometric gap widths, we theoretically demonstrate that two structures that consist of splitting and recombining MGWs and of coupling MGWs can be used as nanoscale Mach–Zehnder interferometers. MGW arrays show capabilities for array imaging and for controlling the flow of SPPs. Other potential applications of coupling MGWs, as SPP switches, directional couplers, and even as a nanoscale counterpart for observing linear and nonlinear dynamic behavior of electromagnetic fields, are also predicted and discussed. Our results point to an interesting way to manipulate optical signals and provide efficient sensing in nanophotonic architectures.

Clinical review of 580 ranulas.

Abstract: Objective The purpose of this paper was to compare clinical features among 3 patterns of ranula and the recurrence rates of each when treated by different surgical methods. Methods A retrospective review of clinical and pathologic records in 580 ranulas was undertaken. Ranulas were classified into 3 clinical types according to sites of the primary swelling: oral ranula, plunging ranula, and mixed ranula. Information was collected on age at presentation, sex, history of onset, sites of swelling, surgical methods, histological findings, and outcome of treatment. Results Ranula was most prevalent in the second decade of life and slightly more common in females (male to female ratio of 1:1.2), but a distinct male predilection was noted for the plunging ranula (male to female ratio of 1:0.74). Oral ranula was most commonly involved in the left side (left to right ratio of 1:0.62), while the plunging and mixed ranula were commonly involved in the right side (left to right ratio of 1:1.38, 1:1.16 respectively). In the plunging ranula group, there were more patients who had the history more than 6 months. The recurrence rates of ranulas were not related to swelling patterns and surgical approaches, but intimately related to the methods of surgical procedures. The recurrent rates for marsupialization, excision of ranula, and excision of the sublingual gland or gland combined with lesion were 66.67%, 57.69%, and 1.20%, respectively. Conclusion Three patterns of ranula have similar clinical and histopathologic findings, although plunging ranula has some different clinical features. Removal of the sublingual gland via an intraoral approach is necessary in the management of various clinical patterns of the ranula. Recurrence rates of ranulas of any type are excessive unless the involved sublingual gland is removed.

Functionalized CdSe quantum dots as selective silver ion chemodosimeter.

Abstract: CdSe quantum dots (QDs) have been prepared and modified with mercaptoacetic acid. They are water-soluble and biocompatible. To improve their fluorescence intensity and stability in water solution, bovine serum albumin (BSA) was absorbed onto their surface. Based on the quench of fluorescence signals of the functionalized CdSe QDs in the 543 nm wavelength and enhancement of them in the 570–700 nm wavelength range by Ag(I) ions at pH 5.0, a simple, rapid and specific method for Ag(I) determination was proposed. In comparison with single organic fluorophores, these nanoparticles are brighter, more stable against photobleaching, and do not suffer from blinking. Under the optimum conditions, the response is linearly proportional to the concentration of Ag(I) between 4.0 × 10−7 and 1.5 × 10−5 mol L−1, and the limit of detection is 7.0 × 10−8 mol L−1. The mechanism of reaction is also discussed.

Stepwise metastatic human hepatocellular carcinoma cell model system with multiple metastatic potentials established through consecutive in vivo selection and studies on metastatic characteristics

Abstract: To establish a “stepwise metastatic human hepatocellular carcinoma (HCC) cell model system” for in-depth study of the underlying mechanisms of HCC metastasis. Using MHCC97— a metastatic human hepatocellular carcinoma (HCC) cell line reported in 1999—as the parent cells, we subsequently established three cell lines (MHCC97-L, HMCC97-H, and HCCLM3) with increasing spontaneous metastatic potential. Now, the fourth cell line with unique multiple metastatic characteristics has been established by six rounds of in vivo selection. This cell line, designated as HCCLM6, is a polygonal epithelial cell with hypotriploid karyotype, the modal chromosomes are 55-58, and marker chromosomal abnormalities include i(1) (q10), i(8)(q10), der (4) t(4;8)(q31;q22), i(X)(q10). The cell population doubling time was 32 h. Fluorescent PCR showed HBV DNA integration in the cellular genome. Thirty-five days after HCCLM6 was injected subcutaneously into BALB/c nude mice, prominent lung metastases occurred in 100% of the recipient animals. When tumor tissue was orthotopically implanted into the liver of nude mouse, widespread loco-regional and pulmonary metastases occurred. Inoculation of this cell into the footpad of nude mice also produced 75% regional lymph node metastasis. Compared with MHCC97-L which was not metastastatic via subcutaneous or footpad inoculation and 40% metastatic via orthotopic inoculation, HCCLM6 had increased expression of matrix metalloproteinase (MMP-2 and MMP-9) and cytokeratin 19 (CK19), and decreased expression of Rb2/p130. The establishment of this new cell line has completed our stepwise metastatic HCC cell mode system, which was characterized by a similar genetic background but with significant differences in spontaneous metastasis behavior. The study supports the theory that cancer metastasis is a highly selective dynamic process and the cell model system could be a useful platform for the study of HCC metastasis.

Novel Fibers Prepared from Cellulose in NaOH/Urea Aqueous Solution

Abstract: Novel regenerated cellulose fibers have been successfully spun from the cellulose dope in NaOH/urea aqueous solution, which could rapidly dissolve cellulose. The fibers possess circular cross-sections as well as relatively high molecular weight, and a crystallinity index with cellulose II family crystal structure, leading to good mechanical properties. This technology is simple, cheap, and environmentally friendly, promising to substitute for viscose rayon production having hazardous byproducts.

Effect of irrigation method and N-fertilizer management on rice yield, water productivity and nutrient-use efficiencies in typical lowland rice conditions in China

Abstract: Alternate wetting and drying irrigation (AWD) has been reported to save water compared with continuous flooding (CF) in rice cultivation However, the reported effects on yield varied greatly and detailed agro-hydrological characterization is often lacking so that generalizations are difficult to make Furthermore, it is not known how AWD modifies nutrient use efficiencies and if it requires different N-fertilizer management compared with CF This study quantified the agro-hydrological conditions of the commonly practiced AWD and compared the impact of AWD and CF irrigations at different N-fertilizer management regimes on rice growth and yield, water productivity, and fertilizer-use efficiencies in five crop seasons in 1999 and 2000 at two typical lowland rice sites in China (Jinhua, Zheijang Province and Tuanlin, Hubei Province), with shallow groundwater tables

Vp28 of shrimp white spot syndrome virus is involved in the attachment and penetration into shrimp cells.

Abstract: White spot disease (WSD) is caused by the white spot syndrome virus (WSSV), which results in devastating losses to the shrimp farming industry around the world. However, the mechanism of virus entry and spread into the shrimp cells is unknown. A binding assay in vitro demonstrated VP28-EGFP (envelope protein VP28 fused with enhanced green fluorescence protein) binding to shrimp cells. This provides direct evidence that VP28-EGFP can bind to shrimp cells at pH 6.0 within 0.5 h. However, the protein was observed to enter the cytoplasm 3 h post-adsorption. Meanwhile, the plaque inhibition test showed that the polyclonal antibody against VP28 (a major envelope protein of WSSV) could neutralize the WSSV and block an infection with the virus. The result of competition ELISA further confirmed that the envelope protein VP28 could compete with WSSV to bind to shrimp cells. Overall, VP28 of the WSSV can bind to shrimp cells as an attachment protein, and can help the virus enter the cytoplasm.