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Abstract The InAs/GaSb superlattice infrared detector has been developed with tremendous effort. However, the performance of it, especially long-wavelength infrared detectors (LWIR), is still limited by the electrical performance and optical quantum efficiency (QE). Forcing the active region to be p-type through proper doping can highly improve QE, and the gating technique can be employed to greatly enhance electrical performance. However, the saturation bias voltage is too high. Reducing the saturation bias voltage has broad prospects for the future application of gate voltage control devices. In this paper, we report that the gated P+–π–M–N+ InAs/GaSb superlattice long-wavelength infrared detectors exhibit different π region doping levels that have a reduced minimum saturation bias at − 10 V with a 200-nm SiO2 layer after a simple and effective anodic vulcanization pretreatment. The saturation gate bias voltage is much lower than − 40 V that reported with the same thickness of a 200-nm SiO2 passivation layer and similar structure. The optical and electrical characterization indicates that the electrical and optical performance of the device would be weakened by excessive doping concentration. At 77 K, the 50% cutoff wavelength of the device is about 8 µm, the 100% cutoff wavelength is 10 µm, the maximum quantum efficiency is 62.4%, the maximum of responsivity is 2.26 A/W at 5 µm, and the maximum RA of the device is 1259.4 Ω cm2. Besides, the specific detectivity of Be 780 °C-doped detector without gate electrode exhibits a peak of 5.6 × 1010 cm Hz1/2/W at 5 µm with a 70-mv reverse bias voltage, which is more than three times that of Be 820 °C-doped detector. Moreover, the peak specific detectivity could be further increased to 1.3 × 1011 cm Hz1/2/W at 5 µm with a 10-mv reserve bias voltage that has the bias of − 10 V at the gate electrode.

A long-/long-wave dual-color detector with N-M-π-B-π-M-N structure was developed based on a type-II InAs/GaSb superlattice. The saturated responsivity was achieved under low bias voltage for both channels. The device could be operated as a single detector for sequential detection and showed high quantum efficiencies. The peak quantum efficiencies of long-wavelength infrared band-1 (blue channel) and long-wavelength infrared band-2 (red channel) were 44% at 6.3 μm under 20 mV and 57% at 9.1 μm under −60 mV, respectively. The optical performance for each channel was achieved using a 2 μm thickness absorber. Due to the high QE, the specific detectivities of the blue and red channels reached 5.0 × 1011 cm·Hz1/2/W at 6.8 μm and 3.1 × 1011 cm·Hz1/2/W at 9.1 μm, respectively, at 77 K. [ABSTRACT FROM AUTHOR]

In this paper, we demonstrate bias-selectable dual-band short- or mid-wavelength infrared photodetectors based on In0.24Ga0.76As0.21Sb0.79 bulk materials and InAs/GaSb type-II superlattices with cutoff wavelengths of 2.2 μm and 3.6 μm, respectively. At 200 K, the short-wave channel exhibits a peak quantum efficiency of 42% and a dark current density of 5.93 × 10−5 A/cm2 at 500 mV, thereby providing a detectivity of 1.55 × 1011 cm⋅Hz1/2/W. The mid-wave channel exhibits a peak quantum efficiency of 31% and a dark current density of 1.22 × 10−3 A/cm2 at −300 mV, thereby resulting in a detectivity of 2.71 × 1010 cm⋅Hz1/2/W. Moreover, we discuss the band alignment and spectral cross-talk of the dual-band n-i-p-p-i-n structure. [ABSTRACT FROM AUTHOR]

In this paper we focused on the mask technology of inductively coupled plasma (ICP) etching for the mesa fabrication of infrared focal plane arrays (FPA). By using the SiO2 mask, the mesa has higher graphics transfer accuracy and creates less micro-ripples in sidewalls. Comparing the IV characterization of detectors by using two different masks, the detector using the SiO2 hard mask has the of , while the detector using the photoresist mask has the of in 77 K. After that we focused on the method of removing the remaining SiO2 after mesa etching. The dry ICP etching and chemical buffer oxide etcher (BOE) based on HF and NH4F are used in this part. Detectors using BOE only have closer to that using the combining method, but it leads to gaps on mesas because of the corrosion on AlSb layer by BOE. We finally choose the combining method and fabricated the 640× 512 FPA. The FPA with cutoff wavelength of 4.8 m has the average of and the average detectivity of at 77 K. The FPA has good uniformity with the bad dots rate of 1.21% and the noise equivalent temperature difference (NEDT) of 22.9 mK operating at 77 K. [ABSTRACT FROM AUTHOR]

A very long wavelength infrared(VLWIR) focal plane array based on InAs/GaSb type-II super-lattices is demonstrated on a GaSb substrate. A hetero-structure photodiode was grown with a 50% cut-off wavelength of 15.2 m, at 77 K. A 320×256 VLWIR focal plane array with this design was fabricated and characterized. The peak quantum efficiency without an antireflective coating was 25.74% at the reverse bias voltage of −20 mV, yielding a peak specific detectivity of cm·Hz ·W−1. The operability and the uniformity of response were 89% and 83.17%. The noise-equivalent temperature difference at 65 K exhibited a minimum at 21.4 mK, corresponding to an average value of 56.3 mK. [ABSTRACT FROM AUTHOR]

We report a type-II InAs/GaSb superlattice three-color infrared detector for mid-wave (MW), long-wave (LW), and very long-wave (VLW) detections. The detector structure consists of three contacts of NIPIN architecture for MW and LW detections, and hetero-junction NIP architecture for VLW detection. It is found that the spectral crosstalks can be significantly reduced by controlling the minority carriers transport via doping beryllium in the two active regions of NIPIN section. The crosstalk detection at MW, LW, and VLW signals are achieved by selecting the bias voltages on the device. At 77K, the cutoff wavelengths of the three-color detection are 5.3 μm (at 0 mV), 14 μm (at 300 mV) and 19 μm (at −20 mV) with the detectivities of 4.6×1011 cm·Hz1/2 W−1, 2.3 × 1010 cm·Hz1/2W−1, and 1.0×1010 cm·Hz1/2W−1 for MW, LW and VLW. The crosstalks of the MW channel, LW channel, and VLW channel are almost 0, 0.25, and 0.6, respectively. [ABSTRACT FROM AUTHOR]

The purpose of the present study was to develop a novel transdermal drug-delivery system comprising a polyamidoamine dendrimer coupled with sonophoresis to enhance the permeation of diclofenac (DF) through the skin. The novel transdermal drug-delivery system was developed by using a statistical Plackett-Burman design. Hairless male Wistar rat skin was used for the DF-permeation study. Coupling media concentration, ultrasound-application time, duty cycle, distance from probe to skin, and a third-generation polyamidoamine-dendrimer concentration were selected as independent variables, while in vitro drug release was selected as a dependent variable. Independent variables were found to be statistically significant (P<0.05). DF gel without dendrimer and ultrasound treatment to skin (passive delivery, run 13) showed 56.69 µg/cm(2) cumulative drug permeated through the skin, while the DF-dendrimer gel without sonophoresis treatment (run 14) showed 257.3 µg/cm(2) cumulative drug permeated through the skin after 24 hours. However, when the same gel was applied to sonophoresis-treated skin, drastic permeation enhancement was observed. In the case of run 3, the cumulative drug that permeated through the skin was 935.21 µg/cm(2). It was concluded that dendrimer-coupled sonophoresis-mediated transdermal drug delivery system has the potential to enhance the permeation of DF through the skin.

Objective: To test the effect of short interfering RNAs (siRNAs) of beta-site APP cleaving enzyme (BACE) on inhibiting the expression of BACE in mammalian cells., Methods: The gene of EGFP, U6 promoter and beta-secretase targeting siRNA were cloned by PCR. The PCR products were inserted into the retrovirus plasmid pLXSN. The interfering vector was identified as pLXSN/ EGFP-U6-siBACE. The SK-N-SH cell line was produced, which can highly expressed BACE. The inhibitive effect of BACE siRNA on BACE expression was examined by fluoroscopy and immunohistochemistry tests., Results: The interfering vector, pLXSN/EGFP-U6-siBACE, was constructed successfully. The BACE siRNA inhibited the expression of BACE in the SK-N-SH cell and reduced the production of Abeta., Conclusion: BACE siRNA inhibits the expression of BACE gene of mammalian, which has implications for RNA interference of Alzheimer's disease.

Objective: To investigate whether short interfering RNAs(siRNAs) of beta-site APP cleaving enzyme (BACE) can inhibit the expression of BACE in mammalian cells., Methods: The gene of EGFP, U6 promoter and beta-secretase targeting siRNA were cloned by PCR, respectively. The PCR products were inserted into plasmid pLXSN. The interfering vector pLXSN/EGFP-U6-siBACE was transferred into SK-N-SH cells to express BACE. The inhibition effect of BACE siRNA on BACE expression was investigated by fluoroscopy and immunohistochemistry method., Result: The interfering vector pLXSN/EGFP-U6-siBACE was constructed successfully. The BACE siRNA inhibited the expression of BACE in the SK-N-SH cells specifically and effectively, and the production of A beta was reduced., Conclusion: BACE siRNA can inhibit the expression of BACE gene of mammalian cells.

Objective: To investigate the tumor-suppression effect of PA combined with GM-CSF, TNF-alpha and IL-4 on cord blood mononuclear cells (CBMC)., Methods: The mononuclear cells were isolated from human umbilical cord blood and cultured with polyacttin A (PA), GM-CSF + TNF-alpha + IL-4 (GTI), and GTI + PA (GTIP) respectively. Six days later, surface antigen expression of the cultured cells, including CD1a and CD83, which were the specialized markers of dendritic cell (DC), were analyzed by immunohistochemistry technique. The CBMC were cultured with GTI for 24 h to enhance DC, then were added apoptotic/necrotic Hela/HepG2 tumor cells, and finally PA was co-cultured. The antitumor cytotoxicity of CBMC was measured by MTT assay., Results: After the culture, CD1a and CD83 positive cell rates of the PA group inreased significantly, reaching (19.63 +/- 3.61)%, (9.28 +/- 4.31) % respectively, much higher than that of the control, but lower than that of the GTI group. The killing rate to the tumor cells of CBMC cultured with GTIP increased remarkably, much higher than the control, GTI and PA groups. After tumor antigens were added to the CBMC of GTIP group (GTIP + Tc), the killing rate increased., Conclusion: PA not only promotes the proliferation and maturation of cord blood derived DC, but also improves the tumor-suppression effect of CBMC cultured with GTI.

Aim: To study the expression of fusion gene Abeta-HBcAg in E.coli and detect the immunogenicity of fusion protein Abeta-HBcAg., Methods: The Abeta-HBcAg fusion gene was cut from recombinant plasmid pBV220/Abeta-HBcAg, and was inserted into the plasmid pYTA1 to construct recombinant plasmid pYTA/Abeta-HBcAg. The recombinant plasmid was transformed into E.coli DH5alpha, and expressed under IPTG induction. The expression of the fusion protein Abeta-HBcAg was detected by SDS-PAGE. The antigenicity of the fusion protein was detected by ELISA. BALB/c mice were immunized intraperitoneally with the fusion protein purified by salting out with saturate ammonium sulfate. The titers of anti- Abeta antibodies of the immunized mice was evaluated by ELISA., Results: Fusion protein existed in supernatant of the bacteria lysate and its expression level was about 7% of the total bacteria protein. The fusion protein reacted with both Abeta and HBcAg. The highest titer of anti-Abeta antibodies could reach to 1:16 000 after immunization for 3 times., Conclusion: Recombinant gene Abeta-HBcAg can be expressed in E.coli DH5alpha. The expression protein exists in supernatant of the bacteria lysate and has good immunogenicity. This study lays the foundation for the experimental animal study of AD gene-engineering vaccine.