A real-time monitoring reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay was developed for the sensitive and specific detection of prototypic,prevalent North American porcine reproductive an...A real-time monitoring reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay was developed for the sensitive and specific detection of prototypic,prevalent North American porcine reproductive and respiratory syndrome virus (PRRSV) strains.As a higher sensitivity and specificity method than reverse transcription polymerase chain reaction (RT-PCR),the RT-LAMP method only used a turbidimeter,exhibited a detection limit corresponding to a 10-4 dilution of template RNA extracted from 250 μL of 105 of the 50% tissue culture infective dose (TCID50) of PRRSV-containing cells,and no cross-reactivity was observed with other related viruses including porcine circovirus type 2,swine influenza virus,porcine rotavirus and classical swine fever virus.From forty-two field samples,33 samples in the RT-LAMP assay was detected positive,whereas three of which were not detected by RT-PCR.Furthermore,in 33 strains of PRRSV,an identical detection rate was observed with the RT-LAMP assay to what were isolated using porcine alveolar macrophages.These findings demonstrated that the RT-LAMP assay has potential clinical applications for the detection of highly pathogenic PRRSV isolates,especially in developing countries.展开更多
Ⅲ-Ⅴ quantum dot(QD) lasers monolithically grown on CMOS-compatible Si substrates are considered as essential components for integrated silicon photonic circuits.However,epitaxial growth of Ⅲ-Ⅴ materials on Si subs...Ⅲ-Ⅴ quantum dot(QD) lasers monolithically grown on CMOS-compatible Si substrates are considered as essential components for integrated silicon photonic circuits.However,epitaxial growth of Ⅲ-Ⅴ materials on Si substrates encounters three obstacles:mismatch defects,antiphase boundaries(APBs),and thermal cracks.We study the evolution of the structures on U-shaped trench-patterned Si(001) substrates with various trench orientations by homoepitaxy and the subsequent heteroepitaxial growth of GaAs film.The results show that the formation of(111)-faceted hollow structures on patterned Si(001) substrates with trenches oriented along [110] direction can effectively reduce the defect density and thermal stress in the GaAs/Si epilayers.The(111)-faceted silicon hollow structure can act as a promising platform for the direct growth of Ⅲ-Ⅴ materials for silicon based optoelectronic applications.展开更多
A high quality epitaxial Si layer by molecular beam epitaxy(MBE)on Si(001)substrates was demonstrated to fabricate a channel with low density defects for high-performance Fin FET technology.In order to study the effec...A high quality epitaxial Si layer by molecular beam epitaxy(MBE)on Si(001)substrates was demonstrated to fabricate a channel with low density defects for high-performance Fin FET technology.In order to study the effects of fin width and crystallography orientation on the MBE behavior,a 30 nm thick Si layer was deposited on the top of an etched Si fin with different widths from 10 nm to 50 nm and orientations of 100 and 110.The result shows that a defect-free Si film was obtained on the fin by MBE,since the etching damage was confined in the bottom of the epitaxial layer.In addition,the vertical growth of the epitaxial Si layer was observed on sub-10 nm 100 Si fins,and this was explained by a kinetic mechanism.展开更多
GaAs/Ge heterostructures have been employed in various semiconductor devices such as solar cells,high-performance CMOS transistors,andⅢ-Ⅴ/Ⅳheterogeneous optoelectronic devices.The performance of these devices is di...GaAs/Ge heterostructures have been employed in various semiconductor devices such as solar cells,high-performance CMOS transistors,andⅢ-Ⅴ/Ⅳheterogeneous optoelectronic devices.The performance of these devices is directly dependent on the material quality of the GaAs/Ge heterostructure,while the material quality of the epitaxial GaAs layer on the Ge is limited by issues such as the antiphase domain(APD),and stacking-fault pyramids(SFP).We investigate the epitaxial growth of high-quality GaAs on a Ge(001)mesa array,via molecular beam epitaxy.Following a systematic study of the Ge terrace via an in situ scanning tunneling microscope,an atomically step-free terrace on the Ge mesa measuring up to 5×5μm^(2) is obtained,under optimized growth conditions.The step-free terrace has a single-phase c(4×2)surface reconstruction.The deposition of a high-quality GaAs layer with no APD and SFP is then achieved on this step-free Ge terrace.High-resolution transmission electron microscopy and electron channel contrast image characterizations reveal the defect-free growth of the GaAs layer on the step-free Ge mesa.Furthermore,InAs quantum dots on this GaAs/Ge mesa reveal photoluminescent intensity comparable to that achieved on a GaAs substrate,which further confirms the high quality of the GaAs layer on Ge.展开更多
文摘A real-time monitoring reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay was developed for the sensitive and specific detection of prototypic,prevalent North American porcine reproductive and respiratory syndrome virus (PRRSV) strains.As a higher sensitivity and specificity method than reverse transcription polymerase chain reaction (RT-PCR),the RT-LAMP method only used a turbidimeter,exhibited a detection limit corresponding to a 10-4 dilution of template RNA extracted from 250 μL of 105 of the 50% tissue culture infective dose (TCID50) of PRRSV-containing cells,and no cross-reactivity was observed with other related viruses including porcine circovirus type 2,swine influenza virus,porcine rotavirus and classical swine fever virus.From forty-two field samples,33 samples in the RT-LAMP assay was detected positive,whereas three of which were not detected by RT-PCR.Furthermore,in 33 strains of PRRSV,an identical detection rate was observed with the RT-LAMP assay to what were isolated using porcine alveolar macrophages.These findings demonstrated that the RT-LAMP assay has potential clinical applications for the detection of highly pathogenic PRRSV isolates,especially in developing countries.
基金the National Natural Science Foundation of China under Grant Nos.61635011,61975230,61804177,11434041 and 11574356the National Key Research and Development Program of China(2016YFA0300600 and 2016YFA0301700)+1 种基金the Key Research Program of Frontier Sciences,CAS(No.QYZDB-SSW-JSC009)Ting Wang is supported by the Youth Innovation Promotion Association of CAS(No.2018011).
文摘Ⅲ-Ⅴ quantum dot(QD) lasers monolithically grown on CMOS-compatible Si substrates are considered as essential components for integrated silicon photonic circuits.However,epitaxial growth of Ⅲ-Ⅴ materials on Si substrates encounters three obstacles:mismatch defects,antiphase boundaries(APBs),and thermal cracks.We study the evolution of the structures on U-shaped trench-patterned Si(001) substrates with various trench orientations by homoepitaxy and the subsequent heteroepitaxial growth of GaAs film.The results show that the formation of(111)-faceted hollow structures on patterned Si(001) substrates with trenches oriented along [110] direction can effectively reduce the defect density and thermal stress in the GaAs/Si epilayers.The(111)-faceted silicon hollow structure can act as a promising platform for the direct growth of Ⅲ-Ⅴ materials for silicon based optoelectronic applications.
基金the National Key Research and Development Program of China(Grant No.2016YFA0200504)the National Natural Science Foundation of China(Grant No.61927901)。
文摘A high quality epitaxial Si layer by molecular beam epitaxy(MBE)on Si(001)substrates was demonstrated to fabricate a channel with low density defects for high-performance Fin FET technology.In order to study the effects of fin width and crystallography orientation on the MBE behavior,a 30 nm thick Si layer was deposited on the top of an etched Si fin with different widths from 10 nm to 50 nm and orientations of 100 and 110.The result shows that a defect-free Si film was obtained on the fin by MBE,since the etching damage was confined in the bottom of the epitaxial layer.In addition,the vertical growth of the epitaxial Si layer was observed on sub-10 nm 100 Si fins,and this was explained by a kinetic mechanism.
基金Supported by the National Natural Science Foundation of China(Grant Nos.61975230,61635011,61804177 and 11804382)the National Key Research and Development Program of China(Grant No.2018YFB2200104)+1 种基金Beijing Municipal Science and Technology Commission(Grant No.Z191100004819010)the Key Research Program of Frontier Sciences,CAS(Grant No.QYZDB-SSW-JSC009)。
文摘GaAs/Ge heterostructures have been employed in various semiconductor devices such as solar cells,high-performance CMOS transistors,andⅢ-Ⅴ/Ⅳheterogeneous optoelectronic devices.The performance of these devices is directly dependent on the material quality of the GaAs/Ge heterostructure,while the material quality of the epitaxial GaAs layer on the Ge is limited by issues such as the antiphase domain(APD),and stacking-fault pyramids(SFP).We investigate the epitaxial growth of high-quality GaAs on a Ge(001)mesa array,via molecular beam epitaxy.Following a systematic study of the Ge terrace via an in situ scanning tunneling microscope,an atomically step-free terrace on the Ge mesa measuring up to 5×5μm^(2) is obtained,under optimized growth conditions.The step-free terrace has a single-phase c(4×2)surface reconstruction.The deposition of a high-quality GaAs layer with no APD and SFP is then achieved on this step-free Ge terrace.High-resolution transmission electron microscopy and electron channel contrast image characterizations reveal the defect-free growth of the GaAs layer on the step-free Ge mesa.Furthermore,InAs quantum dots on this GaAs/Ge mesa reveal photoluminescent intensity comparable to that achieved on a GaAs substrate,which further confirms the high quality of the GaAs layer on Ge.