Sintering of SiC-TiB2-B4C composite was carried out by SPS at 1900 degrees C and hot forging was applied at 2050 degrees C to improve mechanical and thermal properties. A fully dense ceramic, with density of 3.08 g/cm...
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Sintering of SiC-TiB2-B4C composite was carried out by SPS at 1900 degrees C and hot forging was applied at 2050 degrees C to improve mechanical and thermal properties. A fully dense ceramic, with density of 3.08 g/cm3 was obtained after SPS and the properties of the composite improved after hot forging. During SPS sintering, TiB2 and graphite phases were in-situ formed consuming all TiC. Very strong orientation of graphite, coarsening of grain size and reduction in both liquid phase and porosities were observed after hot forging. While fracture toughness increased without compromising hardness and flexural strength, the thermal conductivity was doubled depending on the orientation of the in-situ formed graphite after hot forging. The hardness, fracture toughness, thermal conductivity, elastic modulus and density of the sintered and hot forged composites were measured as 32.2-32.8 GPa, 4.0-4.4 MPa.m1/2, 27.8-58.1 W m-1 K-1, 280-315 GPa and 3.12-3.08 g/cm3 respectively.
Viral hemorrhagic septicemia virus (VHSV) is a significant pathogen causing mass mortalities in marine and freshwater fish worldwide. Accurate diagnosis through quantitative reverse transcription PCR (RT-qPCR) is esse...
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Viral hemorrhagic septicemia virus (VHSV) is a significant pathogen causing mass mortalities in marine and freshwater fish worldwide. Accurate diagnosis through quantitative reverse transcription PCR (RT-qPCR) is essential to prevent its spread, but false negatives can compromise results. In this study, we evaluate the use of heat-inactivated snakehead rhabdovirus (SHRV) as an internal positive control (IPC) for VHSV diagnosis. SHRV's similarity to VHSV in viral structure and genome makes it an ideal IPC. The introduction of SHRV IPC into the RT-qPCR workflow can improve the reliability of diagnostic results by enabling the detection of technical failures during the RNA extraction or amplification process. Our results show that heat-inactivated SHRV preserved RNA integrity for IPC use, and SHRV IPC can provide a useful tool for detecting and interpreting false negatives without affecting assay sensitivity.
Viral hemorrhagic septicemia (VHS) is one of the most serious viral diseases of cultured olive flounder in Korea. This study validated the sensitivities of one-step and two-step reverse-transcription PCR (RT-PCR) meth...
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Viral hemorrhagic septicemia (VHS) is one of the most serious viral diseases of cultured olive flounder in Korea. This study validated the sensitivities of one-step and two-step reverse-transcription PCR (RT-PCR) methods based on the OIE (World Organization for Animal Health) diagnostic manual for the detection of VHSV type IVa isolates from olive flounder in Korea. VHSV type I was used as a positive control for the VHSV VN primer set listed in the OIE manual;the PCR products amplified from VHSV I appeared as strong gel bands of the target size, but the PCR products amplified from the VHSV IVa Korean isolate appeared as faint bands. Sequence comparison revealed that the VHSV VN forward primer was mismatched at 4 out of 24 nucleotide positions within the corresponding VHSV type IVa sequence, but differed only by a single nucleotide in the case of VHSV I. Therefore, the VHSV VN IVa primer set was designed specifically to fit the VHSV IVa sequence, and this was used in RT-PCR. The PCR products amplified from VHSV IVa appeared as strong bands of the target size when the VHSV VN IVa primer set was used, but the PCR products of VHSV I appeared as faint bands. PCR titration results showed that the sensitivity of the VHSV VN IVa primer set for VHSV IVa was 100,000-fold higher than that of the VHSV VN primer set when one-step RT-PCR was used, and that the sensitivity was >10,000-fold higher than that of the VHSV VN primer set when the two-step RT-PCR method was used with oligo dT + random hexamer. The sensitivity of the VHSV VN IVa primer set for VHSV IVa was found to be 10,000-fold higher than that of the VHSV VN primer set when the two-step RT-PCR method was used with the target primer set. Therefore, the RT-PCR methods that are used in pathogen-diagnosis laboratories must be validated according to the specificity of the primer set and the one-step or two-step RT-PCR method employed, using either the target primer set or oligo dT + random hexamer. (C) 2015 Elsevier B.V. Al
We propose and experimentally demonstrate an all-optical upconverter for the generation of an optical single-sideband (OSSB) signal in radio-over-fiber (RoF) systems. The OSSB signal, which is required for overcoming ...
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We propose and experimentally demonstrate an all-optical upconverter for the generation of an optical single-sideband (OSSB) signal in radio-over-fiber (RoF) systems. The OSSB signal, which is required for overcoming the fiber chromatic dispersion problem in RoF systems, is generated by using an all-optical SSB upconverter consisting of an optical interleaver and a semiconductor optical amplifier. With this upconversion technique, OSSB radio frequency (RF) signals with an RF frequency ranging from 15 GHz to 42.5 GHz are generated by mixing an optical intermediate frequency (IF) signal (1 GHz) with an optical local oscillator signal and transmitted over a 46 km standard single-mode fiber. The OSSB RF signal generated by this upconversion technique shows negligible dispersion-induced carrier suppression effects, which are usually observed for an optical double-sideband RF signal. The all-optical SSB upconverter provides high conversion efficiency of up to 29 dB and a sufficiently large spurious free dynamic range of 82 dB(.)Hz(2/3) for microcellular personal communication system applications. (C) 2009 Optical Society of America
We have experimentally demonstrated a full-duplex wavelength division-multiplexing-based radio-over-fiber system using all-optical single-sideband (SSB) frequency upconversion and wavelength re-use techniques for broa...
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We have experimentally demonstrated a full-duplex wavelength division-multiplexing-based radio-over-fiber system using all-optical single-sideband (SSB) frequency upconversion and wavelength re-use techniques for broadband optical-wireless access networks. The optical SSB RF signal having the RF frequency of 62.5 GHz is generated by using this all-optical frequency upconverter that consists of an arrayed waveguide grating for optical demultiplexing and a semiconductor optical amplifier for wavelength conversion based on the cross-gain modulation effect. The receiver sensitivity at the bit error rate of 10(-9) is -11.5 and -32.5 dBm for downlink (including air transmission of 1.5 m) and uplink, respectively. The power penalties originating from the fiber chromatic dispersion are negligible after transmission over 25-km standard mode fibers (SMFs) for both downlink and uplink. For the IF wavelengths from 1530 to 1580 nm (covering C-band), the variation of the receiver sensitivity is less than 2.5 dB.
An all-optical frequency downconversion utilizing a four-wave mixing effect in a single semiconductor optical amplifier (SOA) was experimentally demonstrated for wavelength division multiplexing (WDM) radio-over-fiber...
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An all-optical frequency downconversion utilizing a four-wave mixing effect in a single semiconductor optical amplifier (SOA) was experimentally demonstrated for wavelength division multiplexing (WDM) radio-over-fiber (RoF) applications. Two WDM optical radio frequency (RF) signals having 155 Mbps differential phase shift keying (DPSK) data at 28.5 GHz were simultaneously down-converted to two WDM optical intermediate frequency (IF) signals having an IF frequency of 4.5 GHz by mixing with an optical local oscillator (LO) signal having a LO frequency of 24 GHz in the SOA. The bit-error-rate (BER) performance of the RoF up-links with different optical fiber lengths employing all-optical frequency downconversion was investigated. The receiver sensitivity of the RoF up-link with a 6 km single mode fiber and an optical IF signal in an optical double-sideband format was approximately -8.5 dBm and the power penalty for simultaneous frequency downconversion was approximately 0.63 dB. The BER performance showed a strong dependence on the fiber length due to the fiber dispersion. The receiver sensitivity of the RoF up-link with the optical IF signal in the optical single-sideband format was reduced to approximately -17.4 dBm and showed negligible dependence on the fiber length. (C) 2012 Optical Society of America
Polymerase chain reaction (PCR) assays allow for the rapid and accurate detection of infectious agents through identification of nucleic acid sequences. However, contamination of samples with positive DNA can lead to ...
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Polymerase chain reaction (PCR) assays allow for the rapid and accurate detection of infectious agents through identification of nucleic acid sequences. However, contamination of samples with positive DNA can lead to false-positive results. In this study, positive control plasmids were developed to minimize false-positive reactions due to PCR contamination during detection of SVCV by semi-nested reverse-transcription PCR. An ampicillin resistance gene was truncated by PCR amplification, and the fragments were inserted into pGEM-T Easy vectors;the resulting plasmids were named SVCV chimeric plasmid-1 and chimeric plasmid-2, respectively. Through a series of semi-nested PCRs, the use of SVCV chimeric plasmids-1 and -2 was shown to ensure correct diagnoses, free from PCR contamination. The results of this study show that PCR positive controls can be created without use of viral nucleic acids or pathogen-infected tissues. The technique can be applied to quarantined material and can be used to detect other pathogens. (C) 2012 Elsevier B.V. All rights reserved.
Viral hemorrhagic septicemia virus (VHSV), causing severe diseases in farmed fish, is detected and genotyped using conventional reverse-transcription PCR (cRT-PCR) targeting the nucleoprotein gene with corresponding V...
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Viral hemorrhagic septicemia virus (VHSV), causing severe diseases in farmed fish, is detected and genotyped using conventional reverse-transcription PCR (cRT-PCR) targeting the nucleoprotein gene with corresponding VN F (forward) and VN R (reverse) primers. However, these primers have low sensitivity to VHSV subtype IVa;I investigated the cause for the poor cRT-PCR performance using various primer combinations. The results demonstrated that a 3-end mismatch in the VN F primer reduced sensitivity and plays a critical role in VHSV detection by cRT-PCR.
A simultaneous all-optical frequency upconversion technique using four-wave mixing in a semiconductor optical amplifier (SOA) is experimentally demonstrated for wavelength-division-multiplexing (WDM) radio-over-fiber ...
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A simultaneous all-optical frequency upconversion technique using four-wave mixing in a semiconductor optical amplifier (SOA) is experimentally demonstrated for wavelength-division-multiplexing (WDM) radio-over-fiber applications. Eight WDM optical radio-frequency (RF) signals having the RF frequency of 26.5 GHz are simultaneously generated by mixing eight WDM optical intermediate-frequency (IF) signals having the IF frequency of 2.5 GHz with an optical local oscillator signal of 24 GHz in a single SOA. The power penalty for simultaneous generation of eight WDM optical RF signals at the bit-error rate of 10(-9) is less than 2.7 dB.
PurposeNoninvasive and real-time detection of tumor sites is highly important for precision cancer surgery. In this study, we developed indocyanine green (ICG)-loaded microspheres as near-infrared (NIR) fluorescence m...
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PurposeNoninvasive and real-time detection of tumor sites is highly important for precision cancer surgery. In this study, we developed indocyanine green (ICG)-loaded microspheres as near-infrared (NIR) fluorescence markers for the noninvasive and long-term localization of tumor *** were prepared using a water-in-oil-in-water method to encapsulate ICGs into small and multiple separated pores inside the microspheres. Microspheres containing different amounts of Poloxamer 188 were evaluated both in vitro and in *** of ICG and the human serum albumin (HSA) complex in the microspheres showed 25-fold higher fluorescence signals than ICG alone. The addition of 1% poloxamer 188 (P-188) to the oil phase resulted in the highest fluorescence signal from the microspheres. When ICG-HSA-loaded microspheres with 1% P-188 were subcutaneously injected into SKH-1 hairless mice, strong fluorescence signals from the injection sites were detected for up to 30 d without a significant reduction in the NIR fluorescence *** ICG dye-loaded microspheres have great potential as long-term fluorescent markers for imaging-guided precision surgery.
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