High-Quality Photoconductive Ultraviolet GaN/6H-SiC Detector and Its Properties

The properties of photoconductive ultraviolet detector based on GaN epilayer grown on 6H-SiC substrate by metalorganic chemical vapor deposition were investigated in this paper. We obtained the detectable energy span of the device up to ultraviolet by photocurrent measurement. The spectral responsivity remained nearly constant for wavelengths from 250 to 365 nm and dropped by three orders of magnitude within 10 nm of the band edge (by 380 nm). The detector was measured to have a responsivity of 133 A/W at a wavelength of 360 nm under a 5-V bias, and the voltage-dependent responsivity was performed. Furthermore, an easy method was developed to determine the response time, and the relationship between response time and bias was obtained.

Wind-induced natural ventilation of re-entrant bays in a high-rise building

This paper reports a systematic computational study of wind-induced natural ventilation and pollutant transport of re-entrant bays on a total of 30 generic building models of different building heights and with bays of different dimensions. Mean wind flow around each building model and wind-induced flow inside re-entrant bays are computed. To determine the ventilation efficiency of the bay, the computed flow field is used to disperse a scalar pollutant initially occupying the entire bay at a uniform concentration. The subsequent time decay of pollutant concentration inside the bay is studied and the ventilation efficiency is quantified by the retention time. The results show that wind-induced flow inside the bay, especially on the building side face, is complex and highly three-dimensional. Air exchange rates through the roof opening and vertical side opening are analyzed for each bay and their relationship to the ventilation efficiency is discussed. The bays on the building side faces are much worse ventilated than those on the windward or leeward building face. The deeper the side bay, the worse is the air exchange and ventilation. The building height is found to have a governing effect on the ventilation of the windward and leeward re-entrant bays.

Low-density to high-density transition in Ce75Al23Si2 metallic glass

Using in situ high-pressure x-ray diffraction (XRD), we observed a pressure-induced polyamorphic transition from the low-density amorphous (LDA) state to the high-density amorphous (HDA) state in Ce(75)Al(23)Si(2) metallic glass at about 2 GPa and 300 K. The thermal stabilities of both LDA and HDA metallic glasses were further investigated using in situ high-temperature and high-pressure XRD, which revealed different pressure dependences of the onset crystallization temperature (T(x)) between them with a turning point at about 2 GPa. Compared with Ce(75)Al(25) metallic glass, minor Si doping shifts the onset polyamorphic transition pressure from 1.5 to 2 GPa and obviously stabilizes both LDA and HDA metallic glasses with higher T(x) and changes their slopes dT(x)/dP. The results obtained in this work reveal another polyamorphous metallic glass system by minor alloying (e.g. Si), which could modify the transition pressure and also properties of LDA and HDA metallic glasses. The minor alloying effect reported here is valuable for the development of more polyamorphous metallic glasses, even multicomponent bulk metallic glasses with modified properties, which will trigger more investigations in this field and improve our understanding of polyamorphism and metallic glasses.

The structure and functions of P-glycoprotein

P-glycoprotein (P-gp) is an ATP-driven transmembrane transporter capable of effluxing a wide variety of structurally diverse and functionally unrelated hydrophobic compounds out of the cell. Multidrug resistance (MDR), often associated with the over-expression of P-gp, has been implicated as a major obstacle to effective chemotherapy for cancer, parasitic diseases, AIDS, and other diseases. Drug efflux mediated by P-gp is also involved in decreasing the oral bioavailability of drugs by limiting intestinal absorption. Our appreciation of the structural and functional aspects of P-gp has definitely improved in recent years, benefiting from the deciphering of the structure of some bacterial transporters that paved the way for construction of homology models for more complex transporters. Here, we will review the recent advances in the studies of the structure and functional characteristics of P-gp with the hopes of facilitating rational drug design in developing novel potent MDR modulators.

Magnetic-field modulation of surface plasmon polaritons on gratings

The propagation of surface plasmon polaritons (SPPs) on gratings can be experimentally modified when magneto-optically active materials are used. We have observed this effect in Au-Co thin-film bilayers where a polymer grating was patterned on the upper surface. In addition, Au-Co-Au trilayers were grown on polycarbonate gratings, and the Co layer thicknesses and placement from the upper interface were varied to further investigate this effect. We show that the Co layer must be tailored to balance optical absorption and magneto-optical activity, while the pitch of the grating can be adjusted to tune the angular dependence of the field-dependent SPP excitation.

Treatment of municipal wastewater using a contact oxidation filtration separation integrated bioreactor

A new contact oxidation filtration separation integrated bioreactor (CFBR) was used to treat municipal wastewater. The CFBR was made up of a biofilm reactor (the upper part of the CFBR) and a gravitational filtration bed (the lower part of the CFBR). Polyacrylonitrile balls (50mm diameter, 237 m(2)/m(3) specific surface, 90% porosity, and 50.2% packing rate) were filled into the biofilm reactor as biofilm attaching materials and anthracite coal (particle size 1-2mm, packing density 0.947 g/cm(3), non-uniform coefficient (K(80)=d(80)/d(10))<2.0) was placed into the gravitational filtration bed as filter media. At an organic volumetric loading rate of 2.4 kg COD/(m(3)d) and an initial filtration velocity of 5m/h in the CFBR, the average removal efficiencies of COD, ammonia nitrogen, total nitrogen and turbidity were 90.6%, 81.4%, 64.6% and 96.7% respectively, but the treatment process seemed not to be effective in phosphorus removal. The average removal efficiency of total phosphorus was 60.1%. Additionally, the power consumption of the CFBR was less than 0.15 kWh/m(3) of wastewater treated, and less than 1.5 kWh/kg BOD(5) removal.

Prolonged cardiac allograft survival in mouse model after complement depletion with Yunnan cobra venom factor

BACKGROUND

Activation of the complement system is the leading mechanism that causes antibody-mediated acute rejection and hyperacute rejection after xenotransplantation. The major cause of acute rejection in allogeneic transplantation is the T cell-mediated specific immune response. We studied the effects of complement on acute rejection after cardiac allotransplantation using complement depletion with cobra venom factor (CVF) in the mouse.

MATERIALS AND METHODS

The Balb/c-C57 mouse model of heterotopic cardiac allograft was used. The mice were divided into 2 groups, a control group and a CVF-treated group. After intravenous injection of CVF, the experimental group was observed for allograft survival time. Twelve mice from the control and experimental groups were sacrificed on days 3, 5, and 7 after the operation. The pathologic grade of acute rejection, deposition of C3 in tissue, extent of infiltration by CD4+ and CD8+ T cells, and expression of MHC-II, B7-1, and B7-2 were compared between the 2 groups.

RESULTS

In the CVF-treated group, mean (SD) survival of the cardiac allograft was 26.2 (1.7) days, and in the control group was 8.4 (0.4) days (P < .01). Pathologic examination and immunohistochemistry demonstrated that the grade of acute rejection, deposition of C3 in tissue, extent of infiltration of CD4+ and CD8+ T cells, and expression of MHC-II, B7-1, and B7-2 were significantly decreased in the CVF-treated group.

CONCLUSION

Depletion of complement in the serum with CVF inhibits acute cardiac allograft rejection in the mouse.

Master and slave transluminal endoscopic robot (MASTER) for natural orifice transluminal endoscopic surgery (NOTES)

Although the flexible endoscopy has been widely used in the medical field for many years, there is still great potential in improving the endoscopist's capability to perform therapeutic tasks. Tentatively, tools for the flexible endoscope have poor maneuverability and limited Degree Of Freedom (DOF). In this paper, we propose a surgical robotic system MASTER (Master And Slave Transluminal Endoscopic Robot). MASTER is a dexterous and flexible master-slave device which can be used in tandem with a conventional flexible endoscope. Using this robotic system, ESD (Endoscopic Submucosal Dissection) and NOTES (Natural Orifice Transluminal Endoscopic Surgery) have been conducted on in vivo and ex vivo animal trials with promising results.

Magnetic field modulation of intense surface plasmon polaritons

We present correlated experimental and theoretical studies on the magnetic field modulation of Surface Plasmon Polaritons (SPPs) in Au/Co/Au trilayers. The trilayers were grown by sputter deposition on glass slides with the Co films placed at different distances from the surface and with different thickness. We show that it is possible to tailor Au/Co/Au trilayers with the critical thickness needed for optimum excitation of SPPs leading to large localized electromagnetic fields. The modification of the SPP wave vector by externally applied magnetic fields was investigated by measuring the magneto-optical activity in transverse configuration. In addition, using magneto-optics as a tool we determined the spatial distribution of the SPP generated electromagnetic fields within Au/Co/Au samples by analyzing the field-dependent optical response, demonstrating that it is possible to excite SPPs that exhibit large electromagnetic fields that are also magneto-optically active and therefore can be modulated by externally applied magnetic fields.

Contribution of Primary Afferent Input to Trigeminal Astroglial Hyperactivity, Cytokine Induction and NMDA Receptor Phosphorylation

We tested the hypothesis that primary afferent inputs play a role in astroglial hyperactivity after tissue injury. We first injected complete Freund's adjuvant (CFA, 0.05 ml, 1:1 oil/saline) into the masseter muscle, which upregulated glial fibrillary acidic protein (GFAP), a marker of astrocytes, interleukin (IL)-1β an inflammatory cytokine, and phosphorylation of serine896 of the NR1 subunit (P-NR1) of the NMDA receptor in the subnuclei interpolaris/caudalis (Vi/Vc) transition zone, an important structure for processing trigeminal nociceptive input. Local anesthetic block with lidocaine (2%) of the masseter muscle at 10 min prior to injection of CFA into the same site significantly reduced the CFA-induced increase in GFAP, IL-1β and P-NR1 (p<0.05, n=4/group). We then tested the effect of peripheral electrical stimulation (ES). The ES protocol was burst stimulation consisting of trains of 4 square pulses (10-100 Hz, 0.1-3 mA, 0.5 ms pulse width). Under pentobarbital anesthesia, an ES was delivered every 0.2 s for a total of 30 min. The Vi/Vc tissues were processed for immunohistochemistry or western blot analysis at 10-120 min after ES. Compared to naive and SHAM-treated rats, there was increased immunoreactivity against GFAP, IL-1β and P-NR1 in the Vi/Vc in rats receiving ES. Double staining showed that IL-1β was selectively localized in GFAP-positive astroglia, and P-NR1-immunoreactivity was localized to neurons. These findings indicate that primary afferent inputs are necessary and sufficient to induce astroglial hyperactivity and upregulation of IL-1β, as well as neuronal NMDA receptor phosphorylation.

Immune responses to T-cell epitopes of SARS CoV-N protein are enhanced by N immunization with a chimera of lysosome-associated membrane protein

In our previous study by Gupta et al, dominant T-cell epitopes of SARS CoV-N(N) protein were predicted by software. The spectrum of interferon (IFN)-gamma responses of Balb/c mice immunized against two different forms of SARS CoV-N plasmid was then analyzed. A cluster of dominant T-cell epitopes of SARS CoV-N protein was found in the N-terminus (amino acids 76-114). On the basis of this study, four different plasmids were constructed: (i) DNA encoding the unmodified N (p-N) or N(70-122) (p-N(70-122)) as an endogenous cytoplasmic protein or (ii) DNA encoding a lysosome-associated membrane protein (LAMP) chimera with N (p-LAMP/N) or N(70-122) (p-LAMP/N(70-122)). The immune responses of mice to these four constructs were evaluated. The results showed marked differences in the responses of the immunized mice. A single priming immunization with the p-LAMP/N construct was sufficient to elicit an antibody response. Enzyme-linked immunospot (ELISpot) assay indicated that p-LAMP/N(70-122) and p-LAMP/N plasmids both elicited a greater IFN-gamma response than p-N. p-N and p-N(70-122) constructs induced low or undetectable levels of cytokine secretion. We also found that the p-LAMP/N(70-122) construct promoted a long-lasting T-cell memory response without an additional boost 6 months after three immunizations. These findings show that DNA vaccines, even epitope-based DNA vaccines using LAMP as chimera, can elicit both humoral and cellular immune responses.

[Effects of p,p'-DDE on expression of inhibin B in sertoli cells of rats]

OBJECTIVE

To study the effects of p,p'-DDE on the expression of inhibin B in sertoli cells of rats.

METHODS

Sertoli cells were separated and cultured from testicular tissue of rats, and ensured the dose of test materials by MTT test, and RT-PCR were measured on the changes of inhibin B expression.

RESULTS

The results indicated that there was high difference in middle and high dose groups in comparison with control group (P < 0.05), and there were statistical significance in comparison with low dose group, and the gray scale of inhibin B decreased with the increase dose of p,p'-DDE.

CONCLUSION

The results indicated that p,p'-DDE could inhibit the expression of inhibin B.