Under a suitable condition of crystallization, dark brown short rhombohedron crystals could be obtained from FeMoco-deficient MoFe protein (DeltanifE Avl) purified from a nifE deleted mutant DJ35 of Azotobacter vinela...Under a suitable condition of crystallization, dark brown short rhombohedron crystals could be obtained from FeMoco-deficient MoFe protein (DeltanifE Avl) purified from a nifE deleted mutant DJ35 of Azotobacter vinelandii Lipmann grown in NH3-limited medium. The number, size and quality of crystals were significantly affected by either the concentration of precipitants and buffer or diffusion method. The longest sides of the largest crystal of DeltanifE Avl protein, which was obtained by vapor diffusion in the hanging drop method, were 0.12 and 0.13 mm, respectively.展开更多
AVS2 is a new generation video coding standard developed by the AVS working group. Compared with the first generation AVS video coding standard, known as AVS1, AVS2 significantly improves coding performance by using m...AVS2 is a new generation video coding standard developed by the AVS working group. Compared with the first generation AVS video coding standard, known as AVS1, AVS2 significantly improves coding performance by using many new coding technologies, e.g., adaptive block partition and two level transform coding. Moreover, for scene video, e.g. surveillance video and conference vid?eo, AVS2 provided a background picture modeling scheme to achieve more accurate prediction, which can also make object detec?tion and tracking in surveillance video coding more flexible. Experimental results show that AVS2 is competitive with High Effi?ciency Video Coding (HEVC) in terms of performance. Especially for scene video, AVS2 can achieve 39% bit rate saving over HEVC.展开更多
Audio Video Coding Standard （AVS） is a second-generation source coding standard and the first standard for audio and video coding in China with independent intellectual property rights. Its performance has reached t...Audio Video Coding Standard （AVS） is a second-generation source coding standard and the first standard for audio and video coding in China with independent intellectual property rights. Its performance has reached the international standard. Its coding efficiency is 2 to 3 times greater than that of MPEG -2. This technical solution is more simple, and it can greatly save channel resource. After more than ten years＇ development, AVS has achieved great success. The latest version of the AVS audio coding standard is ongoing and mainly aims at the increasing demand for low bitrate and high quality audio services. The paper reviews the history and recent development of AVS audio coding standard in terms of basic features, key techniques and performance. Finally, the future development of AVS audio coding standard is discussed.展开更多
Artemisia annua is an important preferred host of the mirid bug Apolygus lucorum in autumn.Volatiles emitted from A.annua attract A.Iucorum.Volatile artemisinic acid of A.annua is a precursor of artemisinin that has b...Artemisia annua is an important preferred host of the mirid bug Apolygus lucorum in autumn.Volatiles emitted from A.annua attract A.Iucorum.Volatile artemisinic acid of A.annua is a precursor of artemisinin that has been widely investigated in the Chinese herbal medicine field.However,little is known at this point about the biological roles of artemisinic acid in regulating the behavioral trends of A.lucorum.In this study,we collected volatiles from A.annua at the seedling stage by using headspace solid phase microextraction(HS-SPME).Gas chromatography-mass spectrometry(GC-MS) analysis showed that approximately 11.03±6.00 and 238.25±121.67 ng hartemisinic acid were detected in volatile samples and milled samples,respectively.Subsequently,a key gene for artemisinic acid synthesis,the cytochrome P450 gene cyp71 av1,was expressed in engineered Saccharomyces cerevisiae to catalyze the production of artemisinic acid.After the addition of exogenous artemisinic alcohol or artemisinic aldehyde,artemisinic acid was identified as the product of the expressed gene.In electroantennogram(EAG) recordings,3-day-old adult A.lucorum showed significant electrophysiological responses to artemisinic alcohol,artemisinic aldehyde and artemisinic acid.Furthermore,3-day-old female bugs were significantly attracted by artemisinic acid and artemisinic alcohol at a concentration of 10 mmol L,whereas 3-day-old male bugs were attracted significantly by 10 mmol Lartemisinic acid and artemisinic aldehyde.We propose that artemisinic acid and its precursors could be used as potential attractant components for the design of novel integrated pest management strategies to control A.lucorum.展开更多
针对AOMedia Video 1(AV1)编码时间较长的问题,基于不同纹理的视频内容与分区模式之间的联系,引入了虚拟子块的跨块梯度差来衡量图像纹理分布的差异,提出了一种快速块划分决策算法,以跳过非必要的分区模式。利用分区终止块大小与性能损...针对AOMedia Video 1(AV1)编码时间较长的问题,基于不同纹理的视频内容与分区模式之间的联系,引入了虚拟子块的跨块梯度差来衡量图像纹理分布的差异,提出了一种快速块划分决策算法,以跳过非必要的分区模式。利用分区终止块大小与性能损失之间的联系,根据当前块大小自适应调整快速块划分的判断阈值,使得较小的编码块具有较宽松的跳过条件。与libaom相比,该算法在全帧内(All-Intra,AI)配置下平均可节省16.15%的编码时间,同时性能损失较小,有望被用于减少高分辨率视频的编码时间。展开更多
文摘Under a suitable condition of crystallization, dark brown short rhombohedron crystals could be obtained from FeMoco-deficient MoFe protein (DeltanifE Avl) purified from a nifE deleted mutant DJ35 of Azotobacter vinelandii Lipmann grown in NH3-limited medium. The number, size and quality of crystals were significantly affected by either the concentration of precipitants and buffer or diffusion method. The longest sides of the largest crystal of DeltanifE Avl protein, which was obtained by vapor diffusion in the hanging drop method, were 0.12 and 0.13 mm, respectively.
文摘AVS2 is a new generation video coding standard developed by the AVS working group. Compared with the first generation AVS video coding standard, known as AVS1, AVS2 significantly improves coding performance by using many new coding technologies, e.g., adaptive block partition and two level transform coding. Moreover, for scene video, e.g. surveillance video and conference vid?eo, AVS2 provided a background picture modeling scheme to achieve more accurate prediction, which can also make object detec?tion and tracking in surveillance video coding more flexible. Experimental results show that AVS2 is competitive with High Effi?ciency Video Coding (HEVC) in terms of performance. Especially for scene video, AVS2 can achieve 39% bit rate saving over HEVC.
文摘Audio Video Coding Standard （AVS） is a second-generation source coding standard and the first standard for audio and video coding in China with independent intellectual property rights. Its performance has reached the international standard. Its coding efficiency is 2 to 3 times greater than that of MPEG -2. This technical solution is more simple, and it can greatly save channel resource. After more than ten years＇ development, AVS has achieved great success. The latest version of the AVS audio coding standard is ongoing and mainly aims at the increasing demand for low bitrate and high quality audio services. The paper reviews the history and recent development of AVS audio coding standard in terms of basic features, key techniques and performance. Finally, the future development of AVS audio coding standard is discussed.
基金supported by the National Natural Science Foundation of China (31772176 and 31972338)the National Key Research and Development Program of China (2019YFD0300100)
文摘Artemisia annua is an important preferred host of the mirid bug Apolygus lucorum in autumn.Volatiles emitted from A.annua attract A.Iucorum.Volatile artemisinic acid of A.annua is a precursor of artemisinin that has been widely investigated in the Chinese herbal medicine field.However,little is known at this point about the biological roles of artemisinic acid in regulating the behavioral trends of A.lucorum.In this study,we collected volatiles from A.annua at the seedling stage by using headspace solid phase microextraction(HS-SPME).Gas chromatography-mass spectrometry(GC-MS) analysis showed that approximately 11.03±6.00 and 238.25±121.67 ng hartemisinic acid were detected in volatile samples and milled samples,respectively.Subsequently,a key gene for artemisinic acid synthesis,the cytochrome P450 gene cyp71 av1,was expressed in engineered Saccharomyces cerevisiae to catalyze the production of artemisinic acid.After the addition of exogenous artemisinic alcohol or artemisinic aldehyde,artemisinic acid was identified as the product of the expressed gene.In electroantennogram(EAG) recordings,3-day-old adult A.lucorum showed significant electrophysiological responses to artemisinic alcohol,artemisinic aldehyde and artemisinic acid.Furthermore,3-day-old female bugs were significantly attracted by artemisinic acid and artemisinic alcohol at a concentration of 10 mmol L,whereas 3-day-old male bugs were attracted significantly by 10 mmol Lartemisinic acid and artemisinic aldehyde.We propose that artemisinic acid and its precursors could be used as potential attractant components for the design of novel integrated pest management strategies to control A.lucorum.
文摘针对AOMedia Video 1(AV1)编码时间较长的问题,基于不同纹理的视频内容与分区模式之间的联系,引入了虚拟子块的跨块梯度差来衡量图像纹理分布的差异,提出了一种快速块划分决策算法,以跳过非必要的分区模式。利用分区终止块大小与性能损失之间的联系,根据当前块大小自适应调整快速块划分的判断阈值,使得较小的编码块具有较宽松的跳过条件。与libaom相比,该算法在全帧内(All-Intra,AI)配置下平均可节省16.15%的编码时间,同时性能损失较小,有望被用于减少高分辨率视频的编码时间。
