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pam投加量对滤池运行效率的影响

城镇供水 2025年第01期 11-16页

作者：樊玉芳韩颖璐张杨陈肖林瑶北京市自来水集团有限责任公司

已有各类研究表明在给水工艺中投加铁、铝混凝剂的同时投加pam对浊度去除有显著增强作用，但pam的最佳投加量与pam残余量对工艺的影响还需进一步研究。本文通过投加不同浓度的混凝剂及pam，利用混凝试验及生产试验，探究了投加pam对给... 详细信息

已有各类研究表明在给水工艺中投加铁、铝混凝剂的同时投加pam对浊度去除有显著增强作用，但pam的最佳投加量与pam残余量对工艺的影响还需进一步研究。本文通过投加不同浓度的混凝剂及pam，利用混凝试验及生产试验，探究了投加pam对给水厂常规工艺运行效果特别是对滤池运行效率的影响。研究发现投加pam浓度低于0.20mg/L时，滤后水浊度显著降低的同时滤池的周期没有明显缩短，不会对滤池的运行造成影响。且pam的投加量存在与混凝剂的最佳配比，混凝剂铁铝的投加浓度较低时，pam投加的最佳浓度区间为0.05～0.10mg/L，混凝剂铁铝的投加浓度较高时，pam投加的最佳浓度区间为0.10～0.15mg/L。

关键词：给水厂 pam 滤池沉淀池浊度

A 10-20 Gb/s pam2-4 transceiver in 65 nm CMOS

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Journal of Semiconductors 2009年第1期30卷 54-58页

作者：高茁杨袆钟石强杨旭黄令仪胡伟武 Institute of Computing Technology Chinese Academy of Sciences Beijing 100083 China Graduate University of the Chinese Academy of Sciences Beijing 100049 China

This paper presents the design of a 10 Gb/s pam2, 20 Gb/s pam4 high speed low power wire-line transceiver equalizer in a 65 nm CMOS process with 1 V supply voltage. The transmitter occupies 430 × 240 μm2 and consumes 50.56 mW power. With the programmable 5-order pre-emphasis equalizer, the transmitter can compensate for a wide range of channel loss and send a signal with adjustable voltage swing. The receiver equalizer occupies 146 × 186μm^2 and consumes 5.3 mW power.

关键词： serial link pam equalizer pre-emphasis CTLE

Improving Plant Genome Editing with High-Fidelity xCas9 and Non-canonical pam-Targeting Cas9-NG

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Molecular Plant 2019年第7期12卷 1027-1036页

作者： Zhaohui Zhong Simon Sretenovic Qiurong Ren Lijia Yang Yu Bao Caiyan Qi Mingzhu Yuan Yao He Shishi Liu Xiaopei Liu Jiaheng Wang Lan Huang Yan Wang Dibin Baby David Wang Tao Zhang Yiping Qi Yong Zhang Department of Biotechnology School of Life Sciences and Technology Center for Informational Biology University of 曰ectronic Science and Technology of China Room 216 Main Building No. 4 Section 2 North Jianshe Road Chengdu 610054 China Department of Plant Science and Landscape Architecture University of Maryland College Park MD 20742 USA Jiangsu Key Laboratory of Crop Genetics and Physiology Co-Innovation Center for Modern Production Technology of Grain Crops Key Laboratory of Plant Functional Genomics of the Ministry of Education Yangzhou University Yangzhou 225009 China Joint International Research Laboratory of Agriculture and Agri-Product Safety of Ministry of Education of China Yangzhou University Yangzhou 225009 China Indian Institute of Science Education and Research Timpati Andhra Pradesh 517507 India Seven Lakes High School Katy TX 77494 USA Institute for Bioscience and Biotechnology Research University of Maryland Rockville MD 20850 USA

Two recently engineered SpCas9 variants, namely xCas9 and Cas9-NG, show promising potential in improving targeting specificity and broadening the targeting range. In this study, we evaluated these Cas9 variants in the model and crop plant, rice. We first tested xCas9-3.7, the most effective xCas9 variant in mammalian cells, for targeted mutagenesis at 16 possible NGN pam (protospacer adjacent motif) combinations in duplicates. xCas9 exhibited nearly equivalent editing efficiency to wild-type Cas9 (Cas9-WT) at most canonical NGG pam sites tested, whereas it showed limited activity at non-canonical NGH (H = A, C, T) pam sites. High editing efficiency of xCas9 at NGG pams was further demonstrated with C to T base editing by both rAPOBECI and PmCDAI cytidine deaminases. With mismatched sgRNAs, we found that xCas9 had improved targeting specificity over the Cas9-WT. Furthermore, we tested two Cas9-NG variants, Cas9-NGv1 and Cas9-NG, for targeting NGN pams. Both Cas9-NG variants showed higher editing efficiency at most non-canonical NG pam sites tested, and enabled much more efficient editing than xCas9 at AT-rich pam sites such as GAT, GAA, and CAA. Nevertheless, we found that Cas9-NG variants showed significant reduced activity at the canonical NGG pam sites. In stable transgenic rice lines, we demonstrated that Cas9-NG had much higher editing efficiency than Cas9-NGv1 and xCas9 at NG pam sites. To expand the base-editing scope, we developed an efficient C to T base-editing system by making fusion of Cas9-NG nickase (D10A version), PmCDAI, and UGI. Taken together, our work benchmarked xCas9 as a high-fidelity nuclease for targeting canonical NGG pams and Cas9-NG as a preferred variant for targeting relaxed pams for plant genome editing.

关键词： xCas9 Cas9-NG high fidelity non-canonical pam base editing

Genome editing mediated by SpCas9 variants with broad non-canonical pam compatibility in plants

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Molecular Plant 2021年第2期14卷 352-360页

作者： Juan Li Rongfang Xu Ruiying Qin Xiaoshuang Liu Fanna Kong Pengcheng Wei Key Laboratory of Rice Genetic Breeding of Anhui Province Rice Research InstituteAnhui Academy of Agricultural SciencesHefei 230031P.R.China

Streptococcus pyogenes Cas9(SpCas9)is the most widely used genome editing tool in *** editing induced by SpCas9 strictly requires a canonical NGG protospacer-adjacent motif(pam),significantly limiting its scope of ***,five SpCas9 variants,SpCas9-NRRH,SpCas9-NRCH,SpCas9-NRTH,SpG,and SPRY,were developed to recognize non-canonical pams in human *** this study,these variants were engineered for plant genome editing,and their targeted mutagenesis capabilities were comprehensively examined at various canonical and non-canonical pam sites in rice(Oryza sativa)by stable ***,both cytosine base editors using a rat APOBEC1 or a human APO-BEC3a and adenine base editors using a directly evolved highly compatible TadA*-8e deaminase were developed from these SpCas9 *** results demonstrated that the developed SpCas9 variantsbased base editors readily generated conversions between C.G and T.A in the target sites with noncanonical pams in transgenic rice ***,the toolbox developed in this study substantially expands the scope of SpCas9-mediated genome editing and will greatly facilitate gene disruption and precise editing in plants.

关键词： SpCas9 variant pam rice genome editing base editing

Expanding plant genome-editing scope by an engineered iSpyMacCas9 system that targets A-rich pam sequences

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Plant Communications 2021年第2期2卷 78-88页

作者： Simon Sretenovic Desuo Yin Adam Levav Jeremy D.Selengut Stephen M.Mount Yiping Qi Department of Plant Science and Landscape Architecture University of MarylandCollege ParkMD 20742USA Hubei Academy of Agricultural Sciences Wuhan 430064China Montgomery Blair High School Silver SpringMD 20901USA Center for Bioinformatics and Computational Biology University of MarylandCollege ParkMD 20742USA Department of Cell Biology and Molecular Genetics University of MarylandCollege ParkMD 20742USA Institute for Bioscience and Biotechnology Research University of MarylandRockvilleMD 20850USA

The most popular CRISPR-SpCas9 systemrecognizes canonical NGG protospacer adjacent motifs(pams).Previously engineered SpCas9 variants,such as Cas9-NG,favor G-rich pams in genome *** this manuscript,we describe a new plant genome-editing system based on a hybrid iSpyMacCas9 platform that allows for targeted mutagenesis,C to T base editing,and A to G base editing at A-rich *** study fills amajor technology gap in the CRISPR-Cas9 system for editing NAAR pams in plants,which greatly expands the targeting scope of ***,our vector systems are fully compatible with Gateway cloning and will work with all existing single-guide RNA expression systems,facilitating easy adoption of the systems by *** anticipate that more tools,such as prime editing,homology-directed repair,CRISPR interference,and CRISPR activation,will be further developed based on our promising iSpyMac-Cas9 platform.

关键词： plant genome editing iSpyMacCas9 pam cytosine base editing adenine base editing

Plant genome editing using xCas9 with expanded pam compatibility

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Journal of Genetics and Genomics 2019年第5期46卷 277-280页

作者： Jingying Li Jinman Luo Meilian Xu Shaoya Li Jiahui Zhang Huiyuan Li Lei Yan Yunde Zhao Lanqin Xia Institute of Crop Sciences Chinese Academy of Agricultural SciencesBeijing100081China National Key Laboratory of Crop Genetic Improvement and National Center of Plant Gene Research Huazhong Agricultural UniversityWuhan430070Chin Shaoya Li Jiahui ZhangHuiyuan LiLei Yan Institute of Crop SciencesChinese Academy of Agricultural SciencesBeijing100081China Section of Cell and Developmental Biology University of CaliforniaSan DiegoLa JollaCA92093-0V6USA

CRISPR/Cas enables robust genome editing and has revolution-ized both functional genomics and crop *** specificity of Cas-directed DNA cleavage is strictly determined by a chimeric single guide RNA(SgRNA)and a short protospacer adjacent motif(pam)in the genome(Cong et al,2013;Zetsche et al,2015).The widely used Cas9 from Streptococcus pyogenes(SpCas9)generally recognizes the canonical NGG pam(where N indicates any nucleicacid base)(Miao et al.,2013;Ma et al,2015),making many regionsuntargetable by ***9 VQR and VRER variants,which recog-nize the non-canonical pam sequences of NGA and NGCG,respectively,have been used to expand targetable sequences in plants(Hu et al.,2016).In addition,the applications of other Cas endonucleases such as SaCas9(Staphylococcus aureus Cas9)(Ran et al..2015).

关键词： Plant genome editing pam compatibility

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pam喷施量与施用方式对风沙土风蚀的影响

农业工程学报 2020年第10期36卷 90-98页

作者：白岗栓罗东苗庆丰周楠杜社妮西北农林科技大学水土保持研究所杨凌712100 中国科学院水利部水土保持研究所杨凌712100 陕西怡安建设工程有限公司西安710021 内蒙古农业大学水利与土木建筑工程学院呼和浩特010020

固定流沙和减少风蚀是一个世界性的难题。pam(聚丙烯酰胺,polyacrylamide)作为一种线性高分子聚合物,喷洒在土壤表层能形成结皮,能有效抵御风蚀,但喷施pam溶液的结皮状况及抗风蚀能力与pam的喷施量及土壤特性等密切相关,且pam溶液的浓... 详细信息

固定流沙和减少风蚀是一个世界性的难题。pam(聚丙烯酰胺,polyacrylamide)作为一种线性高分子聚合物,喷洒在土壤表层能形成结皮,能有效抵御风蚀,但喷施pam溶液的结皮状况及抗风蚀能力与pam的喷施量及土壤特性等密切相关,且pam溶液的浓度越大则黏性越强,越不易喷洒。为了探寻pam防风固沙的适宜喷施量及简便施用方法,该研究以乌兰布和沙漠流动沙丘的风沙土为试验材料,以风沙土的风干土及饱和湿土为对照,首先探讨pam不同喷施量对风干土(风沙土)表层结皮状况、土壤含水率及土壤风蚀量的影响,以寻求pam的适宜喷施量,然后再将适量的pam干撒、干撒后喷水和喷施于风干土表层,探寻pam的简便施用方法。结果表明:1)pam不同喷施量的结皮覆盖度、结皮厚度、结皮抗剪强度均随pam喷施量的增加而增加,均显著高于风干土和饱和湿土;pam不同喷施量的土壤含水率均高于风干土,且随时间的延续均显著高于饱和湿土;喷施1、2、3和4g/m^2的pam风蚀量分别为风干土的26.83%、14.10%、13.01%和13.00%,为饱和湿土的28.78%、15.12%、14.02%和13.94%,当pam喷施量达到2 g/m^2时,pam能有效降低风沙土的风蚀量。2)将2g/m^2的pam干撒、干撒后喷水和喷施于风干土表层,干撒pam后喷水和喷施pam溶液的土壤结皮覆盖度、结皮厚度、结皮抗剪强度均高于风干土、饱和湿土和干撒pam,干撒pam的土壤表层结皮覆盖度低于饱和湿土但高于风干土,结皮厚度和结皮抗剪强度高于风干土及饱和湿土,干撒pam后喷水及喷施pam溶液的土壤含水率高于风干土、饱和湿土及干撒pam,干撒pam的土壤含水率与风干土基本一致。干撒pam、干撒pam后喷水和喷施pam溶液的风蚀量分别为风干土的53.13%、11.17%和6.35%,为饱和湿土的76.34%、16.05%和9.12%,干撒pam后喷水的抗风蚀能力接近于风沙土表层喷施pam溶液。3)由于喷施pam溶液需消耗大量的水分及人力,建议风沙区可在降雨前将2 g/m^2的pam干撒于土壤表层或干撒后向土壤喷水,可有效减少风蚀量。

关键词：土壤水分 pam 施用量施用方法结皮风蚀

pam对黄土高原主要土壤类型水稳性团聚体的改良效果及机理研究

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农业工程学报 2008年第1期24卷 45-49页

作者：曹丽花赵世伟梁向锋刘合满杨永辉赵勇钢中国科学院水利部水土保持研究所黄土高原土壤侵蚀与旱地农业国家重点实验室西北农林科技大学资源与环境科学学院杨凌712100 河南省农业科学院土壤肥料研究所郑州450002

通过室内土柱培养,研究pam对黑垆土、黄绵土、风沙土水稳性团聚体的改良效果,并探讨其作用机理和合理的施用浓度。结果表明,在浓度为0.05%～0.4%,pam均可促进3种土壤>0.25 mm水稳性团聚体的形成,并有效降低3种土壤团聚体分形维数,改善... 详细信息

通过室内土柱培养,研究pam对黑垆土、黄绵土、风沙土水稳性团聚体的改良效果,并探讨其作用机理和合理的施用浓度。结果表明,在浓度为0.05%～0.4%,pam均可促进3种土壤>0.25 mm水稳性团聚体的形成,并有效降低3种土壤团聚体分形维数,改善土壤结构;方差分析表明,pam改良3种土壤结构的机理是一致的,将1 mm的水稳性团聚体含量增加。pam改良黑垆土、黄绵土和风沙土土壤水稳性团聚体达到显著水平时的浓度也不相同,其适宜浓度分别为0.2%～0.4%,0.05%,0.05%。3种土壤的黏粒含量和有机质含量的差异,可能是影响pam对不同土壤的水稳性团聚体的改良效果差异的主要原因。

关键词： pam 水稳性团聚体分形维数

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伪码调相与pam复合测距系统研究

宇航学报 2004年第2期25卷 152-157页

作者：刘己斌赵惠昌南京理工大学电光学院南京210094

介绍了pam伪随机码的构成原理,推导了pam伪随机码的自相关函数和功率谱密度,结合图形分析了它们的性质特点。设计了伪码调相与pam复合测距系统,并分析了在加性高斯白噪声信道中的各个阶段的信号形式。研究了复合测距系统的性能,详细推... 详细信息

介绍了pam伪随机码的构成原理,推导了pam伪随机码的自相关函数和功率谱密度,结合图形分析了它们的性质特点。设计了伪码调相与pam复合测距系统,并分析了在加性高斯白噪声信道中的各个阶段的信号形式。研究了复合测距系统的性能,详细推导了复合测距系统的信噪比增益。结果表明,与单纯的伪码测距系统相比,复合测距系统有更强的抗干扰性能和测距能力。

关键词：伪随机码 pam 测距自相关函数功率谱抗噪声