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Phosphatases play a crucial role in recycling organic phosphorus and determining primary production and phytoplankton communities in seawater, especially in phosphate-depleted coastal waters. The present study analyzed spatiotemporal variation in phosphomonoesterase (PMEase) activity (PMEA) and phosphodiesterase (PDEase) activity (PDEA) during 2 dinoflagellate blooms occurring in 2 coastal areas of Fujian Province, East China Sea, which differed in external phosphate conditions. Together with environmental variables and with a specific focus on the availability of different phosphorus forms in the seawater, the regulation of both phosphatases was studied. The results showed that dissolved organic phosphorus (DOP) was the major phosphorus source during blooms, especially in phosphate-depleted environments. Labile DOP accounted for more than 50% of DOP, of which phosphomonoester (PME) and phosphodiester (PDE) accounted for 75-94% and 6-25%, respectively. PMEA and PDEA were highly correlated, both increasing during blooms with a fixed PMEA:PDEA ratio of 2.5 under external phosphate conditions at both sites. Both PMEA and PDEA were negatively correlated with dissolved inorganic phosphorus (DIP) when phosphate was depleted, but positively correlated with DOP regardless of external phosphate conditions. During dinoflagellate blooms, temperature and phytoplankton biomass were the dominant variables determining both phosphatase activities under phosphate-depleted conditions, whereas the availability of DOP was the dominant variable determining both phosphatase activities under phosphate-replete conditions. This study suggests the importance of phosphatases in recycling DOP, and indicates similar regulation of PMEA and PDEA during dinoflagellate blooms.

To investigate genotype and phenotype of congenital nephrogenic diabetes insipidus caused by AVPR2 mutations, which is rare and limitedly studied in Chinese population. 88 subjects from 28 families with NDI in a department (Beijing, PUMCH) were screened for AVPR2 mutations. Medical records were retrospectively reviewed and characterized. Genotype and phenotype analysis was performed. 23 AVPR2 mutations were identified, including six novel mutations (p.Y117D, p.W208R, p.L313R, p.S127del, p.V162Sfs*30 and p.G251Pfs*96). The onset-age ranged from 1 week to 3 years. Common presentations were polydipsia and polyuria (100%) and intermittent fever (57%). 21% and 14% of patients had short stature and mental impairment. Urine SG and osmolality were decreased, while serum osmolality and sodium were high. Urological ultrasonography results showed hydronephrosis of the kidney (52%), dilation of the ureter (48%), and thickened bladder wall or increased residual urine (32%), led to intermittent urethral catheterization (7%), cystostomy (11%) and binary nephrostomy (4%). Urological defects were developed in older patients. Genotype and phenotype analysis revealed patients with non-missense mutations had higher levels of serum sodium than missense mutations. In the first and largest case series of NDI caused by AVPR2 mutations in Chinese population, we established genetic profile and characterized clinical data, reporting six novel mutations. Further, we found genotype was associated with phenotype. This knowledge broadens genotype and phenotype spectrum of rare congenital NDI caused by AVPR2 mutations, and provides basis for studying molecular biology of AVPR2.

Basic knowledge of the deformation behavior of fabricated components is of paramount importance in materials processing. Compared to other process methods, the mechanics of metal imprinting, especially at small scales, have received relatively less research attention. However, recent demands for tuning the properties of metal surfaces by forming undulated micropatterns have spurred interest in gaining additional insight into metal imprinting. The aim of this study, therefore, was to develop effective modeling capabilities that establish a ground base for exploring the mechanics of this process. Accordingly, a finite element analysis was performed to analyze the deformation of an elastic–plastic material exhibiting isotropic strain hardening imprinted by a rigid template with a nominally flat or patterned surface. Simulation results were obtained in the form of dimensionless quantities to elucidate the effects of pattern geometry, depth of imprinting, and friction on the evolution of plasticity in the deformed material and its plastic flow behavior into the pattern cavities. In addition to insight into the mechanics of the process, this study provides a computational methodology for adjusting key design and process parameters so as to enhance the efficiency of metal imprinting.

Laboratory tests were conducted to evaluate the influence of the positions of positive and negative electrodes on the electrical response of a leak in the geomembrane. A numerical evaluation was performed to model the laboratory conditions and to investigate the effect of dipole spacing, excitation voltage, and impoundment resistivity on the leak detection sensitivity. The results of laboratory tests show that leaks cannot be identified when the positive electrode is very close to the leak and the electrical response of a leak in the geomembrane is independent of the position of the negative electrode. The results from the 3D finite element model indicate that leak detection sensitivity improves nonlinearly as the dipole spacing increases, and it tends to be stable after the dipole spacing exceeds 5% of the length of the survey line. The results also indicate that there is an almost linear increase in the leak detection sensitivity with increasing excitation voltage. Substantial improvement was obtained in the leak detection sensitivity for a greater impoundment resistivity. The numerical results indicate that 90% of leaks in a geomembrane liner can be effectively detected and accurately located for the 3D finite element model of a geomembrane lined earth-rock dam.

Background Toll-like receptors (TLRs) are expressed on human melanocytes, and play an important role in innate and acquired immunity. The role of TLRs in the pathogenesis of vitiligo has not been fully described. Aim To investigate the expression of TLRs in melanocytes from patients with vitiligo and healthy controls (HCs). Methods Primary cultured vitiligo and control melanocytes were obtained from perilesional normal skin of patients with generalized vitiligo and HCs. TLRs mRNA expression in melanocytes were determined by real-time reverse transcription PCR and protein expression by western blotting. Apoptosis was analysed using an annexin V-fluorescein isothiocyanate apoptosis detection kit, and tyrosinase activity and melanin content were measured by a modified dopachrome and colorimetric method. Interleukin (IL)-6, IL-8 and soluble cell adhesion molecule (sICAM)-1 expression were measured by ELISA. Results In vitiligo melanocytes, compared with control melanocytes, apoptosis rate, expression of TLR7 and TLR9 mRNA and protein, and production of IL-8, IL-6 and sICAM-1 were significantly increased, whereas tyrosinase activity and melanin content were significantly decreased. Conclusions Our results suggest that the increased expression of TLR7 and TLR9 might correlate with melanocyte dysfunction in vitiligo.

A series of short-term puncture tests is conducted to investigate the deformation behavior of a 0.5-mm-thick high-density polyethylene (HDPE) geomembrane on particulate underliners subjecte...

A series of uniaxial tensile tests was conducted to investigate the large-strain tensile behaviour of high-density polyethylene (HDPE) geomembranes with defects. The experimental optical technique of 3D digital image correlation (DIC) was used to measure the full-field displacements and strains of the geomembranes during the tensile process. The differences between the average axial elongations and the local strains of intact geomembranes were discussed based on the strain measurement results for different tensile phases. For geomembranes with defects, large local strains near the defects sharply increased with increasing average axial elongations and the influence ranges of different types of defects in the geomembranes exhibited small differences after large tensile deformations. Compared with an intact geomembrane, defects significantly changed the local tensile behaviour of a geomembrane.

Geomembranes are thin polymeric sheets used as barriers to liquid or gas intrusion in earth structures due to their low permeability. The mechanical behavior of geomembrane-soil interfaces ...

In this study, an enhanced constitutive model is developed for coarse granular soil within the framework of generalized plasticity (Pastor, Zienkiewicz, and Chan, 1990). In this model, particle breakage is also considered by introducing the state parameter and the compression index into the plastic modulus, loading vectors, and plastic flow direction vectors of a generalized plasticity model. The calibration of constitutive parameters of the enhanced model is addressed in detail. The numerical simulation of triaxial tests for two types of coarse granular soils under different confining pressures is carried out to illustrate the particle breakage performance of the enhanced model. The good agreement between numerical results and experimental data indicates that the enhanced model can accurately characterize the influence of particle breakage on essential behavior of coarse granular soils.

Geomembranes have been widely applied in hydraulic systems and mineral and environmental engineering. For geomembrane-lined soil structures, such as dikes, dams, and landfills, the geomembrane-soil interface could be a potentially unstable plane under static and dynamic loading. In this study, a large-scale shear apparatus was employed to investigate the monotonic and cyclic shear behaviour of a geomembrane-sand interface under varying normal stress and shear-displacement amplitude. A nonlinear mathematical piecewise model was developed to simulate pre-peak stress-dependent stiffness and post-peak displacement-softening behaviour for the monotonic shear response of the geomembrane-sand interface. Furthermore, the study provided a modeling approach based on the Masing rule to represent the nonlinearity and hysteresis of the cyclic shear behaviour of the interface. The predictions made by the two proposed models were both in good agreement with the experimental monotonic and cyclic shear-test data.

The wave field on the artificial boundary was separated into the free field without local topography effect and scattering field induced by local topography effect. The simulation of the free field under obliquely incident waves was conducted. Based on the assumption that the components of design ground motion were treated as the coincidence of oblique P wave and oblique SV wave, the relationship between the oblique input waves and the design ground motion was established in the free field. Further, the contributions to the two components of design ground motion of obliquely incident waves were discussed. The calculation model in time domain was achieved by the combination of the propagation characteristics of obliquely incident waves and the artificial boundary in the free field. The seismic response to the design ground motion was produced on the free surface. The verification of the 2D half-space model under oblique input waves indicated that the wave input method can accurately reflect the design ground motion on the free surface. Application of an earth-rock dam showed that oblique incidence of seismic waves results in significantly different dynamic response compared with the normal incidence. The proposed method can also be employed in the seismic analysis of large span structures with nonuniform ground motion input.

Pollination services are compromised by habitat destruction, land-use intensification, pesticides, and introduced species. How pollination services respond to such stressors depends on the capacity of pollinator assemblages to function in the face of environmental disruption. Here, we quantify how pollination services provided to a native plant change upon removal of the non-native, western honey bee (Apis mellifera)-a numerically dominant floral visitor in the native bee-rich ecosystems of southern California. We focus on services provided to clustered tarweed (Deinandra fasciculata), a native, annual forb that benefits from outcross pollination. Across five different study sites in coastal San Diego County, tarweed flowers attracted 70 insect taxa, approximately half of which were native bees, but non-native honey bees were always the most abundant floral visitor at each site. To test the ability of the native insect fauna to provide pollination services, we performed Apis removals within experimental 0.25 m2 plots containing approximately 20 tarweed plants and compared visitation and seed set between plants in removal and paired control plots (n = 16 pairs). Even though 92% of observed floral visits to control plots were from honey bees, Apis removal reduced seed production by only 14% relative to plants in control plots. These results indicate that native insect assemblages can contribute important pollination services even in ecosystems numerically dominated by introduced pollinators.

A series of cyclic shear tests was conducted to reveal the cyclic shear behavior of the interfaces between three types of geomembranes (smooth geomembranes, textured geomembranes, and composite geomembranes) and no-fines concrete. Hysteresis loops and backbone curves were obtained under different vertical pressures and shear-displacement amplitudes. The test results indicate that the textured geomembrane–concrete interface presents higher cyclic friction angles than the other two interfaces. The vertical pressure-dependent shear stiffness and damping ratio were used to evaluate the cyclic shear strength and damping behavior of the different geomembrane–concrete interfaces. In addition, the influence of shear rate and cycle number on the cyclic shear behavior of the geomembrane–concrete interfaces was considered, but there is little difference among experimental data for a specific interface. By analyzing the damage observed for the different geomembranes in the test, the shear behavior of these three interfaces between geomembranes and no-fines concrete was further evaluated. Finally, a reasonable choice of geomembrane is suggested for the stability and integrity of geomembranes in practical geomembrane engineering.

Antifeedant activities of the isolated chemical compounds from Ajuga nipponensis, were studied against adult of striped leaf beetles. The methanol, petroleum ether, ethyl acetate and n-butanol extracts at 1.0 mg/ml, were used in this study. All four extracts exhibited more than 65 antifeedant index at 24 h and ethyl acetate extract showed significant activity against striped leaf beetles with 83.12 antifeedant index. Six compounds and one fraction were isolated by chromatography and their structures were identified by NMR, MS and FTIR spectra. At 2.0 mg/ml for 24 h the three compounds 20-hydroxyecdysone, acacetin and apigenin showed considerable activities with antifeedant indexes 59.29, 51.22 and 61.55, respectively. In contrast to this the antifeedant indexes of acacetin and apigenin, were sharply reduced as the time extended and that of 20-hydroxyecdysone remained unchanged. In addition, the synergistic effects of two mixtures of secondary metabolites, were studied and no sharp difference was observed.

Effects of agricultural activities are obvious in arid‐inland regions. A numerical model for two‐dimensional phreatic groundwater flow was developed based on the water budget in the Minqin oasis, a typical arid‐inland region. The spatial data of source/sink terms were processed by combining global information system (GIS) and the finite element subsurface flow (FEFLOW) model. The verified results showed errors for the model of 0.37 and 0.48 m respectively in the Quanba and Huqu areas. The groundwater level changes were simulated with the developed model. The results indicate that groundwater level maintained a decreasing trend of 1.8 and 1.1m year‐1 respectively in the Quanba and Huqu areas under current water resource utilisation. Therefore, further study is needed to determine the rational exploitation volume of groundwater and distribution schemes for surface water.

The efficacy of pest control of three different oil formulations in multiple low-concentration spray programmes on sweet orange and pummelo were compared with unsprayed and normal farmer-treatments over three years. Phytotoxicity of sprays was assessed in terms of fruit and leafdrop, fruityield and external fruitquality. Trees sprayed with any type of oil had lower pest numbers than unsprayed trees. On sweet orange, the heaviest oil was better than the normal farm practice at controlling chaff scale on fruit and red mite and whitefly on leaves. On pummelo it provided the best control of red mite on leaves. All three oils were as effective as the normal farm practice in control of rust mite on sweet orange fruit and leaves and red mite, rust mite and red scale on pummelo fruit. On sweet orange trees there was no evidence of phytotoxicity, and the external quality of fruit generally improved over time. On pummelo trees, oil sprays were unable to improve the external fruitquality. The number of pummelo per t...

The percent regeneration (PR) of activated carbon (AC) regenerated under various conditions is frequently assessed via batch equilibrium adsorption (loading) tests followed by regeneration and reloading. Newly developed and existing methods for calculating PR, which are based on different experimental protocols, were assessed. The PRs for methods 1–3 are based on the ratio of the solid phase concentrations (or loadings) obtained using regenerated AC to that obtained using virgin AC. Method 1 requires multiple reloading tests with different initial conditions to estimate the regenerated AC loading in equilibrium with the same liquid phase concentration as the virgin AC. Method 2, which uses identical initial conditions in the adsorption and re-adsorption tests, yields loadings that are in equilibrium with different liquid phase concentrations. Method 3 uses the virgin AC isotherm to calculate the ratio between loadings at the liquid phase concentration reached during the reloading test. Methods 1 and 3 are more correct because they compare isotherm loadings at the same equilibrium liquid phase concentrations. Method 2 should be avoided and the results of studies using it need to be re-evaluated. Methods 1–3 yielded unrealistically high PR values for the control (ineffective regenerations) experiments, because they do not account for contaminant left on the AC. PR4, developed to consider residual contaminant, described the control experiments well and should also be the most appropriate for low-intensity regenerations. Unfortunately, it is impossible to establish a priori the degree of the intensity of a regeneration. In addition, if the regeneration greatly reduces the adsorption capacity of the AC, PR4 will yield nonsensical values, so it must be used with extreme care. A sensitivity analysis showed that, although PR3 is not as consistent as PR4, on average their values are relatively close. For intense regenerations, method 1 is the correct method to evaluate PR; however, it requires more experimental effort than the alternatives. A methodology was proposed for exploratory regeneration research involving many conditions to reduce the experimental effort required to calculate PR so as not to limit the scope of the regeneration study.

We have calculated the binding energies of excitons in quantum well structures based on ionic semiconductors by including the electron - hole interactions with the longitudinal optical phonon field. We have taken into account these interactions by using different effective interaction potentials between the electron and the hole as derived by Haken, by Aldrich and Bajaj, and by Pollman and Buttner. We have calculated the binding energies of excitons in several ionic quantum well structures as functions of well width using these effective potentials by following a variational approach. We find that the values of the exciton binding energies calculated using these potentials are always larger than those obtained using a Coulomb potential screened by a static dielectric constant. We compare our results with those of some recent calculations.

VKORC1, CYP2C9 and CYP4F2 are three critical genes associated with inter-individual variation of warfarin dose. Many dosing algorithms containing these gene polymorphisms and demographic characteristics have been set up for better use of warfarin. However, with distinct gene mutation frequencies among different ethnics, dosing algorithms differ greatly. For Chinese, related research just concentrate on Han Chinese, ignoring other Chinese ethnicities. This study aims to detect the popular polymorphisms in these three critical genes in Bai, Tibetan Chinese, to start the exploration of better use of warfarin in Chinese minorities.PCR-based methods were used to analyze VKORC1 3673GA, CYP2C9*3, CYP4F2 rs2108622 CT in Han, Bai and Tibetan Chinese.The differences among the mutation frequencies of the studied genes in three ethnicities were not statistically significant. The frequency of A-allele of VKORC1 3673GA was 92.8%, 90.2%, 90.8% in Bai, Tibetan, Han Chinese, respectively. The frequency of *3-allele in CYP2C9*3 was low in Bai (4.5%), Tibetan (2.8%) and Han Chinese (4.6%). Approximately one fourth of each ethnic had the mutant T-allele of CYP4F2 rs108622. However, Bai Chinese got statistically higher A-allele frequency of VKORC1 3673GA than previously studied Han Chinese did.Bai Chinese got significant higher A-allele frequency of VKORC1 3673GA.

We have developed a variational formalism to calculate the effects of electric and magnetic fields on confined hydrogenic donor states in asymmetric coupled double quantum well structures. It is demonstrated that an electric field applied along the growth axis can easily shift the electron wave function from one quantum well across the center barrier into the neighboring well, without ejecting the electron from a confined donor state. Depending on donor location in the structure, binding energy can either increase or decrease under the applied electric field, as had been found in the case of single quantum wells, but with significantly greater rates of change in response to the external field. The magnetic field applied along the growth axis of the quantum well structure leads to additional quantum confinement, increasing both the donor binding energies and the transition energy between the 1s and 2p+ donor states. Effect of the relative size of the two coupled quantum wells on the donor binding energy is...

To demonstrate the role of cord blood serum on dte long-term culture of bone marrow and provide the experimental foundation for its clinical use, the response of the bone marrow mononuclear cells to the mixed cord blood serum was investigated on the basis of Dexter culture system.In ten samples of human bone marrow, 1 x 10(6) bone marrow mononuclear cells were planted onto the stromal cells layer and cultured for five weeks, Cobblestone area forming cells (CAFC), long-term colony-initiation cells (LTC-IC), and the nuclear cells count in the supernatant was observed.CAFC, LTC-IC were 37.1 +/- 12.4/(ml. well), 40.9 +/- 10.6/(ml. well) respectively in control group. The accounts were increased in the group of 10% MCBS, although it was less than that in mixed cytokines group. When combined with cytokines, 10% MCBS enhanced the growth of CAFC and LTC-IC obviously compared with that when cytokines were used alone. 20% MCBS failed to substitute the role of mixed cytokines plus fatal calf serum on the expansion of CAFC, LTC-IC and NCC.MCBS have the activity of stimulation for hematopoietic stem cells, which is analogous to SCF, IL-3, etc. Its nature and concentration remain to be investigated extensively.

We study binding energies of both excitons and donors in a symmetric double quantum well in the presence of a magnetic field applied parallel to the growth direction. We express wave functions as combinations of Gaussian-type orbitals and subband wave functions of even and odd parities, with variationally determined expansion parameters. By varying the interwell barrier width and well sizes (hence varying the interwell coupling), we obtain binding energies ranging in character from that for a strongly coupled double well to that for a system of two isolated single wells. The behavior of the binding energies as function of the interwell coupling, well sizes, and the magnetic field, as well as the donor position is consistently described with our formalism with naturally included subband mixing effects. The magnetic field leads to stronger confinement of the wave functions and enhances binding energies.

We have developed a variational formalism for calculations of the exciton binding energies in the GaAs-AlAs type-II quantum-well structures in the presence of a magnetic field applied along the growth axis. In contrast to some previous calculations, we take into account the finiteness of the potential barriers at the GaAs-AlAs interfaces and the mismatch of the effective masses of electron and hole across such potential barriers. The exciton wave function is expressed in terms of electron and hole subband wave functions and a multiterm Gaussian-type-orbital expansion, with variationally determined coefficients. The finite overlap of the electron and hole wave functions is found to increase exciton binding energies by up to 10--15 %, depending on thickness of the GaAs and AlAs layers. The application of the magnetic field compresses the excitonic wave functions and is found to enhance their binding energies.

We investigate current driven instabilities of plasma modes in semiconductor heterostructures. Amplification of the plasma modes becomes possible when electrons are driven parallel to the interface by a sufficiently large electric field. Effects of electron-electron and electron-phonon scatterings are included. We find that the idealized, strictly two-dimensional treatment of the charge carriers used in our previous studies is an excellent approximation if only one subband is occupied at T=0, and the frequency of the generated oscillation is much less than the intersubband separation. We also find that if more subbands are occupied, the threshold drift velocity for this instability can be significantly reduced, making it more practical for device applications.

Macrophages are involved in tumor growth and progression. They infiltrate into tumors and cause inflammation, which creates a microenvironment favoring tumor growth and metastasis. However, certain stimuli may induce macrophages to act as tumor terminators. Here we report that the calcineurin B subunit (CnB) synergizes with IFN-γ to make macrophages highly cytotoxic to cancer cells. Furthermore, CnB and IFN-γ act synergistically to polarize mouse tumor-associated macrophages, as well as human monocyte-derived macrophages to an M1-like phenotype. This synergy is mediated by the crosstalk between CnB-engaged integrin αM-p38 MAPK signaling and IFN-γ-initiated p38/PKC-δ/Jak2 signaling. Interestingly, the signal transducer and activator of transcription 1 (STAT1) is a key factor that orchestrates the synergy of CnB and IFN-γ, and the phosphorylation status at Ser727 and Tyr701 of STAT1 is directly regulated by CnB and IFN-γ.

A reversed-phase high performance liquid chromatographic method was developed for the quantitative determination of salicylic acid, resorcinol and chloramphenicol in Junlieping tincture. The operation was carried out on an ODS column with the mobile phase of a mixture of acetonitrile-methanol-water(25:10:65, volume proportion). The eluate was detected at 278 nm wavelength. This method is simple, fast and can be used for the quality control of Junlieping tincture.

To investigate the differentiation of NB4 and MR2 cells induced by tributyrin (TB) in combination with different doses of all-trans retinoic acid (ATRA) and to see if TB can induce apoptosis of NB4 and MR2 cells.Cell differentiation was analyzed by NBT reduction and CD(11b), CD(14) and CD(33), apoptosis by morphology, DNA electrophoresis, flow cytometry (FCM) and TUNEL in situ hybridization, bcl-2 expression by reverse transcriptase polymerase chain reaction.0.2 mmol/L TB in combination with different doses of ATRA could potentiate the differentiation of NB4 cells induced by ATRA alone. No MR2 cell could be markedly induced by ATRA alone or in combination with TB. Treated with 1 mmol/L TB for 24 hours NB4 and MR2 cells exhibited a morphological characteristic of apoptosis and typical DNA ladder on gel electrophoresis. FCM analysis showed that TB could interfere with cell cycle in NB4 and MR2 cells, with a similar ratio of sub-G(1) in both cell lines. TUNEL in situ hybridization confirmed these results. Further study showed that TB could gradually down-regulated bcl-2 expression.TB exerts synergetic effect on ATRA-induced differentiation and induces apoptosis in promyelocytic leukemic cells.

To explore the effect of lovastatin(LOV) on cell growth, apoptosis and differentiation of NB4 cells and elucidate some of the possible mechanism.Cell proliferation and viability were analyzed by MTT assay and trypan blue exclusion assay, cell differentiation by NBT reduction. Cell morphological examination, DNA electrophoresis, flow cytometry, TUNEL in situ hybridization and semi-quantitative RT-PCR were performed to determine cell apoptosis. H,K,N-ras gene expression was investigated by RT-PCR and p21Ras protein expression by flow cytometry.1. LOV inhibited the proliferation of NB4 cells with a lC50 of 12.59 mumol/L. 2. LOV induced apoptosis of NB4 cells, affected the cell cycle progression and arrested NB4 cells in G1/S phase. Bcl-2 mRNA was down-regulated by LOV in a time-dependent manner. 3. LOV could not induce the differentiation of NB4. 4. LOV did not increase the expression of H,K,N-ras mRNA, but decrease p21Ras protein expression on the cellular membrane.LOV can inhibit proliferation, induce apoptosis and interfere with cell cycle progression, but not induce differentiation of NB4. Inhibition of p21Ras protein isoprenylation is considered to be the major mechanism of LOV affecting NB4 cells.

To assess the use of adjustable interatrial communication in patient with severe congenital heart disease undergoing open heart surgery.From February 1998 to June 1999, 13 patients with severe and complex congenital heart disease underwent open heart surgery. Seven patients underwent total cavopulmonary connection, five patients repair of Ebstein's anomaly, and one patient right atrial-pulmonary connection. Adjustable interatrial communication was made in all patients. Four patients had the communication closed at the time of operation, 4 patients had the communication opened at the time of operation, and 5 patients had the communication adjusted and closed postoperatively.All patients had a smooth postoperative process. There were no postoperative death and no severe postoperative complications.Adjustable interatrial communication for the patients undergoing modified Fontan procedure or correction of Ebstein's anomaly may be advantageous.

To review the experience of surgical treatment of ventricular septal defect (VSD) in infants.230 infants with VSD of less than 3 years old underwent surgical repair from Feb. 1990 to Dec. 1997. Their ages ranged from 3 to 36 months. Their weight was 3.2 to 15.5 kg. The number of patients with perimembranous VSD was 192, and that of subpulmonary VSD 36. Two patients had multiple VSDs. 150 patients (65.2%) had moderate or severe pulmonary hypertension before operation.Thirteen patients died during hospitalization period, with a hospital mortality of 5.65%. The main causes of death were pulmonary hypertensive crisis and arrhythmia. The leading complications were pulmonary infections, arrhythmia and pulmonary hypertensive crisis.Surgical treatment of VSD in infancy may have a satisfactory outcome, it standardized surgical techniques and the improved perioperative management are used.

To investigate the retrovirus-mediated transfer and expression of multidrug resistance gene (mdr1) in hematopoietic cells and to develop a model for studying the possible reversal of the MDR-mediated phenotype.A retroviral vector HaMDR expressing the human mdr1 gene was packaged by PA317 cells with a titer of up to 8.5 x 10(5) CFU/ml. K562 leukemia cells were infected with MDR retrovirus, and transfectant K562/MDR cells were generated. The integration and expression of the exogenous mdr1 gene in K562/MDR cells were determined by polymerase chain reaction and flow cytometry. The reversal ability of P-glycoprotein (P-gp) antagonists was analyzed by in vitro drug sensitivity, accumulation and efflux of rhodamine 123 (Rh123) in this model.Transduction with amphotropic MDR retrovirus resulted in integration and expression of the mdr1 gene in the resistant cells, where an aberrant splicing transcript of the mdr1 gene was found. The K562/MDR cells displayed a classic MDR phenotype with a 41-78 fold resistance to vincristine and colchicine in comparison with parental K562 cells. The drug sensitivity of K562/MDR cells to vincristine can be completely restored by cyclosporin A (CsA, 2 mg/L) and Cremophor EL (CRE 132 mg/L), either individually or in combination (P0.05). CsA (3 mg/L) can block the efflux pump function of P-gp shown by the significantly increased accumulation and efflux reduction of Rh123 in K562/MDR cells.Retroviral vector HaMDR allows transfection with high-level expression of the mdr1 gene in human myeloid progenitor cells K562. The transfected K562/MDR provides a simple, sensitive model for developing antagonists of P-gp and studying their mechanism of action.

To establish an efficient and safe gene transfer system mediated by retrovirus for providing an experimental basis of gene therapy in human leukemia.The retrovirus vector pLXSN, carrying the NeoR, was transferred into amphotropic packaging cell line GP + envAm12 by liposome method or by transduction. Retrovirus with higher titer was used to infect human leukemic cell lines NB4, U937 and THP-1. The efficiency of gene transduction was tesed on colonies formed by K562 cells after gene transduction.The titer of DOSPER liposome transfected GP + envAm12 pool on NIH3T3 cells was 8.0 x 10(5) CFU/ml while that of producer pool infected with mouse retrovirus was 1.6 x 10(7) CFU/ml. Integration of NeoR into human leukemic cells was confirmed by PCR. By both nested PCR and NeoR rescue assay, no helper virus was found. NeoR gene transfer with the efficiency as high as 93.3 to 100% in K562 cells was verified by semi-nested PCR on the colonies after seven days' culture.The efficiency and safety of the gene transfer system may provide an optimal experimental system in gene therapy for human leukemia.

We investigate current driven plasma instabilities in quantum wires. We find that such instabilities might be observed in such systems for experimentally achievable drift velocities. We also find, that the threshold drift velocity for this instability is proportional to the Fermi velocity, as was the case in higher dimensional systems. Lowering the Fermi energy of the plasma is thus advantageous for generating these instabilities and possible device applications.

A combined characterization of theoretical calculation and experimental measurements, including Raman scattering, photoluminescence and cross sectional transmission electron microscopy, has been made on GaAs-AlxGai1−xAs multiple quantum wells (MQW) structures with different well widths grown by metalorganic chemical vapor epitaxy (MOCVD) with a modified reactor. Various parameters of these MQWs are obtained. The results with and without the alkyl push flow are compared. Related physical phenomena are discussed.

We have calculated the binding energies of the heavy-hole and the light-hole excitons in the GaAs-AlAs type-II quantum-well structures, taking into account the coupling of the confined electron subband states to the hole subband states, both confined and unconfined. Realistic finite potential barriers are used in the calculations. The inherent lack of reflection symmetry in the type-II quantum wells is shown to lead to a strong mixing of the electron and hole subband wave functions, and to an \ensuremath{\sim}0.5\char21{}2 meV increase in the binding energy of the heavy-hole exciton, and an \ensuremath{\sim}1\char21{}4 meV increase in that of the light-hole exciton. Such increases in the binding energies are attributed to the smaller average electron-hole distance caused by the modified electron and hole charge distributions in the vicinity of the GaAs-AlAs interface, which in turn is the result of mixing of the first electron and hole subbands with the spatially less confined wave functions of higher subbands.

We calculate the binding energies of both the light-hole and heavy-hole excitons in type-II GaAs-AlAs quantum wells in the presence of a magnetic field applied parallel to the axis of growth. Two methods are applied and compared: a variational approach and a perturbation method. The exciton binding energies are calculated assuming infinite potential barriers. The behavior of the exciton binding energies as functions of well widths and the magnetic field is discussed. For a given value of the magnetic field, the exciton binding energies are found to be larger than the zero-magnetic-field case. Results obtained from both methods are compared.

A beam of ballistic electrons moving with a velocity of about twice the Fermi velocity (\ensuremath{\sim}${10}^{7}$ cm/s) with respect to a stationary electron gas is shown to lead to a spontaneous generation of plasmons.

We examine here the possibility of current-driven plasma instabilities in superconductors in two temperature regimes. At low temperatures ($T\ensuremath{\approx}0$) an instability can be generated in a layered system. Near the critical temperature ($T\ensuremath{\approx}{T}_{c}$) an instability can occur in a single superconductor for sufficiently large drifts which might be achievable in the new high-${T}_{c}$ materials. These instabilities offer possibilities for new radiation-source device applications.

On developpe une theorie de la reponse electromagnetique des heterostructures d'un semiconducteur en se basant sur une approche de la fonctiond de Feibelman. On teste cette theorie en etudiant la reponse d'une heterojonction du semiconducteur GaAs−Al x Ga 1−x As et en comparant les resultats aux donnees experimentales appropriees