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利用基于扫描相机的荧光寿命成像显微技术研究细胞周期 被引量:7
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作者 王岩 赵羚伶 +6 位作者 陈同生 许改霞 Artem Pliss Tymish Y.Ohulchanskyy Paras n.prasad 屈军乐 牛憨笨 《中国激光》 EI CAS CSCD 北大核心 2011年第3期127-132,共6页
利用基于扫描相机的荧光寿命成像显微系统,以细胞周期为模型,研究转染绿色荧光蛋白的HeLa细胞的荧光寿命。结果表明,处于周期内不同进程的细胞的荧光寿命为2.50-3.00 ns。处于分裂期的细胞的荧光寿命在1 h内从2.86 ns下降到2.82 ns;在DN... 利用基于扫描相机的荧光寿命成像显微系统,以细胞周期为模型,研究转染绿色荧光蛋白的HeLa细胞的荧光寿命。结果表明,处于周期内不同进程的细胞的荧光寿命为2.50-3.00 ns。处于分裂期的细胞的荧光寿命在1 h内从2.86 ns下降到2.82 ns;在DNA合成前期的8 h内,荧光寿命从2.82 ns下降到2.78 ns。荧光寿命的差异反映了细胞周期中核浆内大分子浓度的变化,对了解细胞周期的分子机制有一定的意义。 展开更多
关键词 成像系统 扫描相机 荧光寿命成像 细胞周期 HELA细胞
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In-situ neutron-transmutation for substitutional doping in 2D layered indium selenide based phototransistor 被引量:7
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作者 Zhinan Guo Yonghong Zeng +9 位作者 Fanxu Meng Hengze Qu Shengli Zhang Shipeng Hu Sidi Fan Haibo Zeng Rui Cao Paras n.prasad Dianyuan Fan Han Zhang 《eLight》 2022年第1期112-120,共9页
Neutron-transmutation doping(NTD)has been demonstrated for the first time in this work for substitutional introduction of tin(Sn)shallow donors into two-dimensional(2D)layered indium selenide(InSe)to manipulate electr... Neutron-transmutation doping(NTD)has been demonstrated for the first time in this work for substitutional introduction of tin(Sn)shallow donors into two-dimensional(2D)layered indium selenide(InSe)to manipulate electron transfer and charge carrier dynamics.Multidisciplinary study including density functional theory,transient optical absorption,and FET devices have been carried out to reveal that the field effect electron mobility of the fabricated phototransistor is increased 100-fold due to the smaller electron effective mass and longer electron life time in the Sn-doped InSe.The responsivity of the Sn-doped InSe based phototransistor is accordingly enhanced by about 50 times,being as high as 397 A/W.The results show that NTD is a highly effective and controllable doping method,possessing good compatibility with the semiconductor manufacturing process,even after device fabrication,and can be carried out without introducing any contamination,which is radically different from traditional doping methods. 展开更多
关键词 Neutron-transmutation doping Substitutional doping Two-dimensional materials PHOTOTRANSISTOR
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Hot-band absorption of indocyanine green for advanced anti-stokes fluorescence bioimaging 被引量:4
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作者 Jing Zhou Xiaoxiao Fan +11 位作者 Di Wu Jie Liu Yuhuang Zhang Zikang Ye Dingwei Xue Mubin He Liang Zhu Zhe Feng Andrey n.Kuzmin Wen Liu Paras n.prasad Jun Qian 《Light(Science & Applications)》 SCIE EI CAS CSCD 2021年第10期1877-1888,共12页
Bright anti-Stokes fluorescence(ASF)in the first near-infrared spectral region(NIR-I,800 nm–900 nm)under the excitation of a 915 nm continuous wave(CW)laser,is observed in Indocyanine Green(ICG),a dye approved by the... Bright anti-Stokes fluorescence(ASF)in the first near-infrared spectral region(NIR-I,800 nm–900 nm)under the excitation of a 915 nm continuous wave(CW)laser,is observed in Indocyanine Green(ICG),a dye approved by the Food and Drug Administration for clinical use.The dependence of fluorescence intensity on excitation light power and temperature,together with fluorescence lifetime measurement,establish this ASF to be originated from absorption from a thermally excited vibrational level(hot-band absorption),as shown in our experiments,which is stronger than the upconversion fluorescence from widely-used rare-earth ion doped nanoparticles.To test the utility of this ASF NIR-I probe for advanced bioimaging,we successively apply it for biothermal sensing,cerebral blood vessel tomography and blood stream velocimetry.Moreover,in combination with L1057 nanoparticles,which absorb the ASF of ICG and emit beyond 1100 nm,these two probes generate multi-mode images in two fluorescent channels under the excitation of a single 915 nm CW laser.One channel is used to monitor two overlapping organs,urinary system&blood vessel of a live mouse,while the other shows urinary system only.Using in intraoperative real-time monitoring,such multi-mode imaging method can be beneficial for visual guiding in anatomy of the urinary system to avoid any accidental injury to the surrounding blood vessels during surgery. 展开更多
关键词 ABSORPTION EXCITATION ANATOMY
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Initial Experience of NIR-II Fluorescence Imaging-Guided Surgery in Foot and Ankle Surgery
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作者 Xiaoxiao Fan Jie Yang +8 位作者 Huwei ni Qiming Xia Xiaolong Liu Tianxiang Wu Lin Li Paras n.prasad Chao Liu Hui Lin Jun Qian 《Engineering》 SCIE EI CAS CSCD 2024年第9期19-27,共9页
Optical imaging in the second near-infrared(NIR-II;900-1880 nm)window is currently a popular research topic in the field of biomedical imaging.This study aimed to explore the application value of NIR-II fluorescence i... Optical imaging in the second near-infrared(NIR-II;900-1880 nm)window is currently a popular research topic in the field of biomedical imaging.This study aimed to explore the application value of NIR-II fluorescence imaging in foot and ankle surgeries.A lab-established NIR-II fluorescence surgical navigation system was developed and used to navigate foot and ankle surgeries which enabled obtaining more high-spatial-frequency information and a higher signal-to-background ratio(SBR)in NIR-II fluorescence images compared to NIR-I fluorescence images;our result demonstrates that NIR-II imaging could provide higher-contrast and larger-depth images to surgeons.Three types of clinical application scenarios(diabetic foot,calcaneal fracture,and lower extremity trauma)were included in this study.Using the NIR-II fluorescence imaging technique,we observed the ischemic region in the diabetic foot before morphological alterations,accurately determined the boundary of the ischemic region in the surgical incision,and fully assessed the blood supply condition of the flap.NIR-II fluorescence imaging can help surgeons precisely judge surgical margins,detect ischemic lesions early,and dynamically trace the perfusion process.We believe that portable and reliable NIR-II fluorescence imaging equipment and additional functional fluorescent probes can play crucial roles in precision surgery. 展开更多
关键词 Second near-infrared fluorescence imaging Foot and ankle surgery Indocyanine green Imaging-guided surgery
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Black phosphorus-based photothermal therapy with aCD47-mediated immune checkpoint blockade for enhanced cancer immunotherapy 被引量:4
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作者 Zhongjian Xie Minhua Peng +9 位作者 Ruitao Lu Xiangying Meng Weiyuan Liang Zhongjun Li Meng Qiu Bin Zhang Guohui nie ni Xie Han Zhang Paras n.prasad 《Light(Science & Applications)》 SCIE EI CAS CSCD 2020年第1期479-493,共15页
Here,we describe a combination strategy of black phosphorus(BP)-based photothermal therapy together with anti-CD47 antibody(aCD47)-based immunotherapy to synergistically enhance cancer treatment.Tumour resistance to i... Here,we describe a combination strategy of black phosphorus(BP)-based photothermal therapy together with anti-CD47 antibody(aCD47)-based immunotherapy to synergistically enhance cancer treatment.Tumour resistance to immune checkpoint blockades in most cancers due to immune escape from host surveillance,along with the initiation of metastasis through immunosuppressive cells in the tumour microenvironment,remains a significant challenge for cancer immunotherapy.aCD47,an agent for CD47/SIRPαaxis blockade,induces modest phagocytic activity and a low response rate for monotherapy,resulting in failures in clinical trials.We showed that BP-mediated ablation of tumours through photothermal effects could serve as an effective strategy for specific immunological stimulation,improving the inherently poor immunogenicity of tumours,which is particularly useful for enhancing cancer immunotherapy.BP in combination with aCD47 blockade activates both innate and adaptive immunities and promotes local and systemic anticancer immune responses,thus offering a synergistically enhanced effect in suppression of tumour progression and in inducing abscopal effects for inhibition of metastatic cancers.Our combination strategy provides a promising platform in which photothermal agents could help to enhance the therapeutic efficacy of immunotherapy. 展开更多
关键词 IMMUNOTHERAPY cancer MEDIATED
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稀土铝合金的发展 被引量:4
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作者 R.Sharan S.n.prasad 张永甲 《轻合金加工技术》 CAS 北大核心 1991年第5期9-13,共5页
1 引言近年来,采用稀土金属作为有色金属合金的有效添加剂引起人们很大的兴趣。据报道,稀土金属能够细化铝合金的组织并改善其机械性能和机加工性能。还有人把稀土添加剂用作Al—Si合金的变质剂。Sharan及其合作者在这方面做了大量研究... 1 引言近年来,采用稀土金属作为有色金属合金的有效添加剂引起人们很大的兴趣。据报道,稀土金属能够细化铝合金的组织并改善其机械性能和机加工性能。还有人把稀土添加剂用作Al—Si合金的变质剂。Sharan及其合作者在这方面做了大量研究与开发工作,所得到的结论在此按时间的先后顺序进行讨论。 1.1 用稀土添加剂作铝及铝合金的晶粒细化剂 Sharan和Anantharaman研究了混合稀土添加剂对纯铝和两种铸造合金(122和218合金)性能的影响。 展开更多
关键词 铝合金 稀土 晶粒细化 工艺性能
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Next generation lanthanide doped nanoscintillators and photon converters 被引量:4
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作者 Lei Lei Yubin Wang +4 位作者 Andrey Kuzmin Youjie Hua Jingtao Zhao Shiqing Xu Paras n.prasad 《eLight》 2022年第1期213-236,共24页
Scintillators are of significance for the realization of indirect X-ray detection and X-ray excited optical luminescence(XEOL)imaging.However,commercial bulk scintillators not only require complex fabrication procedur... Scintillators are of significance for the realization of indirect X-ray detection and X-ray excited optical luminescence(XEOL)imaging.However,commercial bulk scintillators not only require complex fabrication procedures,but also exhibit non-tunable XEOL wavelength and poor device processability.Moreover,thick crystals usually generate light scattering followed by evident signal crosstalk in a photodiode array.Lanthanide doped fluoride nanoscintillators(NSs)prepared with low-temperature wet-chemical method possess several advantages,such as low toxicity,cheap fabrication cost,convenient device processability and adjustable emission wavelengths from ultraviolet to visible and extending to second near infrared window.In addition,they exhibit X-ray excited long persistent luminescence(XEPL)making them suitable for broadening the scope of their applications.This review discusses and summarizes the XEOL and XEPL characteristics of lanthanide doped fluoride NSs.We discuss design strategies and nanostructures that allow manipulation of excitation dynamics in a core-shell geometry to simultaneously produce XEOL,XEPL,as well as photon upconversion and downshifting,enabling emission at multiple wavelengths with a varying time scale profile.The review ends with a discussion of the existing challenges for advancing this field,and presents our subjective insight into areas of further multidisciplinary opportunities. 展开更多
关键词 LANTHANIDE EXCITED FLUORIDE
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Fluorescence lifetime imaging for studying DNA compaction and gene activities 被引量:3
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作者 Svitlana M.Levchenko Artem Pliss +2 位作者 Xiao Peng Paras n.prasad Junle Qu 《Light(Science & Applications)》 SCIE EI CAS CSCD 2021年第12期2349-2359,共11页
Optical imaging is a most useful and widespread technique for the investigation of the structure and function of the cellular genomes.However,an analysis of immensely convoluted and irregularly compacted DNA polymer i... Optical imaging is a most useful and widespread technique for the investigation of the structure and function of the cellular genomes.However,an analysis of immensely convoluted and irregularly compacted DNA polymer is highly challenging even by modern super-resolution microscopy approaches.Here we propose fluorescence lifetime imaging(FLIM)for the advancement of studies of genomic structure including DNA compaction,replication as well as monitoring of gene expression.The proposed FLIM assay employs two independent mechanisms for DNA compaction sensing.One mechanism relies on the inverse quadratic relation between the fluorescence lifetimes of fluorescence probes incorporated into DNA and their local refractive index,variable due to DNA compaction density.Another mechanism is based on the Förster resonance energy transfer(FRET)process between the donor and the acceptor fluorophores,both incorporated into DNA.Both these proposed mechanisms were validated in cultured cells.The obtained data unravel a significant difference in compaction of the gene-rich and gene-poor pools of genomic DNA.We show that the gene-rich DNA is loosely compacted compared to the dense DNA domains devoid of active genes. 展开更多
关键词 expression. LIFETIME DONOR
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Light-induced tumor theranostics based on chemical-exfoliated borophene 被引量:2
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作者 Zhongjian Xie Yanhong Duo +13 位作者 Taojian Fan Yao Zhu Shuai Feng Chuanbo Li Honglian Guo Yanqi Ge Shakeel Ahmed Weichun Huang Huiling Liu Ling Qi Rui Guo Defa Li Paras n.prasad Han Zhang 《Light(Science & Applications)》 SCIE EI CAS CSCD 2022年第12期2886-2899,共14页
Among 2D materials(Xenes)which are at the forefront of research activities,borophene,is an exciting new entry due to its uniquely varied optical,electronic,and chemical properties in many polymorphic forms with widely... Among 2D materials(Xenes)which are at the forefront of research activities,borophene,is an exciting new entry due to its uniquely varied optical,electronic,and chemical properties in many polymorphic forms with widely varying band gaps including the lightest 2D metallic phase.In this paper,we used a simple selective chemical etching to prepare borophene with a strong near IR light-induced photothermal effect.The photothermal efficiency is similar to plasmonic Au nanoparticles,with the added benefit of borophene being degradable due to electron deficiency of boron.We introduce this selective chemical etching process to obtain ultrathin and large borophene nanosheets(thickness of ~4 nm and lateral size up to ~600 nm)from the precursor of AlB_(2).We also report first-time observation of a selective Acid etching behavior showing HCl etching of Al to form a residual B lattice,while HF selectively etches B to yield an Al lattice.We demonstrate that through surface modification with polydopamine(PDA),a biocompatible smart delivery nanoplatform of B@PDA can respond to a tumor environment,exhibiting an enhanced cellular uptake efficiency.We demonstrate that borophene can be more suitable for safe photothermal theranostic of thick tumor using deep penetrating near IR light compared to gold nanoparticles which are not degradable,thus posing longterm toxicity concerns.With about 40 kinds of borides,we hope that our work will open door to more discoveries of this top-down selective etching approach for generating borophene structures with rich unexplored thermal,electronic,and optical properties for many other technological applications. 展开更多
关键词 CHEMICAL uniquely ELECTRONIC
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Morphoanatomic, physicochemical, and phytochemical standardization with HPTLC fingerprinting of aerial parts of Aerva lanata (Linn) Juss ex Schult 被引量:1
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作者 Yuhao Zhao Deepak Kumar +2 位作者 D.n.prasad Rajesh KSingh Yanxu Ma 《Journal of Traditional Chinese Medical Sciences》 2015年第1期39-44,共6页
Objective:Aerva lanata (Linn) Juss ex Schult,family Amaranthaceae,is a common wayside weed.The herb is accepted by the Ayurvedic Formulary of India.This study was undertaken to establish morphoanatomic and physiochemi... Objective:Aerva lanata (Linn) Juss ex Schult,family Amaranthaceae,is a common wayside weed.The herb is accepted by the Ayurvedic Formulary of India.This study was undertaken to establish morphoanatomic and physiochemical standards of A.lanata.Methods:Leaf constants and high-performance thin layer chromatography fingerprint profiles of A.lanata were performed.Results and conclusion:The physico-chemical,morphologic,and histologic parameters presented in this paper may be proposed as standards to establish the authenticity of A.lanata and help differentiate it from other species such as Aerva tomentosa. 展开更多
关键词 Aerva lanata AMARANTHACEAE PHYTOCHEMICAL PHYSICOCHEMICAL Morphoanatomic
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Broadband mid-infrared nonlinear optical modulator enabled by gold nanorods:towards the mid-infrared regime
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作者 BIn HUAnG ZHE KAnG +8 位作者 JIE LI MInGYI LIU PInGHUA TAnG LILI MIAO CHUJUn ZHAO GUAnSHI QIn WEIPInG QIn SHUAnGCHUn WEn PARAS n.prasad 《Photonics Research》 SCIE EI CSCD 2019年第6期699-704,共6页
Mid-infrared pulsed lasers operating around the 3 μm wavelength regime are important for a wide range of applications including sensing, spectroscopy, imaging, etc. Despite the recent advances in technology, the lack... Mid-infrared pulsed lasers operating around the 3 μm wavelength regime are important for a wide range of applications including sensing, spectroscopy, imaging, etc. Despite the recent advances in technology, the lack of a nonlinear optical modulator operating in the mid-infrared regime remains a significant challenge. Here, we report the third-order nonlinear optical response of gold nanorods(GNRs) ranging from 800 nm to the mid-infrared regime(2810 nm) enabled by their size and overlapping behavior-dependent longitudinal surface plasmon resonance. In addition, we demonstrate a wavelength-tunable Er3+-doped fluoride fiber laser modulated by GNRs, which can deliver pulsed laser output, with the pulse duration down to 533 ns, tunable wavelength ranging from 2760.2 to 2810.0 nm, and spectral 3 d B bandwidth of about 1 nm. The experimental results not only validate the GNRs’ robust mid-infrared nonlinear optical response, but also manifest their application potential in high-performance broadband optoelectronic devices. 展开更多
关键词 optical MODULATOR MID-INFRARED REGIME
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Water‑Dispersible CsPbBr_(3) Perovskite Nanocrystals with Ultra‑Stability and its Application in Electrochemical CO_(2) Reduction
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作者 Keqiang Chen Kun Qi +8 位作者 Tong Zhou Tingqiang Yang Yupeng Zhang Zhinan Guo Chang‑Keun Lim Jiayong Zhang Igor Zutic Han Zhang Paras n.prasad 《Nano-Micro Letters》 SCIE EI CAS CSCD 2021年第11期190-202,共13页
Thanks to the excellent optoelectronic properties,lead halide perovskites(LHPs)have been widely employed in highperformance optoelectronic devices such as solar cells and lightemitting diodes.However,overcoming their ... Thanks to the excellent optoelectronic properties,lead halide perovskites(LHPs)have been widely employed in highperformance optoelectronic devices such as solar cells and lightemitting diodes.However,overcoming their poor stability against water has been one of the biggest challenges for most applications.Herein,we report a novel hot-injection method in a Pb-poor environment combined with a well-designed purification process to synthesize water-dispersible CsPbBr_(3) nanocrystals(NCs).The as-prepared NCs sustain their superior photoluminescence(91%quantum yield in water)for more than 200 days in an aqueous environment,which is attributed to a passivation effect induced by excess CsBr salts.Thanks to the ultra-stability of these LHP NCs,for the first time,we report a new application of LHP NCs,in which they are applied to electrocatalysis of CO_(2) reduction reaction.Noticeably,they show significant electrocatalytic activity(faradaic yield:32%for CH4,40%for CO)and operation stability(>350 h). 展开更多
关键词 CsPbBr_(3)nanocrystals Water-dispersible Ultra-stability Electrochemical CO_(2)reduction
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采用新工艺选别印度赤铁矿降低铁份流失提高产品质量
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作者 n.prasad 侯若洲 《国外金属矿选矿》 1989年第6期10-16,28,共8页
本文建议采用有选择性破碎的双流程分选工艺。采用湿式强磁分选工艺对铁矿洗选厂矿泥及尾矿池矿泥进行了选矿试验。这些试验可以获得定性的分选指标对磁场强度的依赖关系。根据已有的技术经济评定,将新的选别工艺引用到赤铁矿的选别实践... 本文建议采用有选择性破碎的双流程分选工艺。采用湿式强磁分选工艺对铁矿洗选厂矿泥及尾矿池矿泥进行了选矿试验。这些试验可以获得定性的分选指标对磁场强度的依赖关系。根据已有的技术经济评定,将新的选别工艺引用到赤铁矿的选别实践中,在经济上是切实可行的。 展开更多
关键词 赤铁矿 双流程分选 铁份 产品质量
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Uptake of transferrin-conjugated quantum dots in single living cells
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作者 陈丹妮 许改霞 +6 位作者 Bahi Ahmed Ali Ken-Tye Yong 周翠红 王晓梅 屈军乐 Paras n.prasad 牛憨笨 《Chinese Optics Letters》 SCIE EI CAS CSCD 2010年第10期940-943,共4页
We study the uptake and distribution of transferrin (Tf)-conjugated CdSe/CdS/ZnS quantum dots (QDs) in single living HeLa cells with both fluorescence confocal microscopy and three-dimensional (3D) reconstructio... We study the uptake and distribution of transferrin (Tf)-conjugated CdSe/CdS/ZnS quantum dots (QDs) in single living HeLa cells with both fluorescence confocal microscopy and three-dimensional (3D) reconstruction technique. By increasing the co-incubation time or the dosage of QDs-Tf, we find that the uptake of QDs-Tf bioconjugates in the cells increases correspondingly, but with different uptake rates. Additionally, the distribution of QDs-Tf, in single live HeLa cells is time dependent. To our knowledge, this is the first study on quantitatively analyzing the uptake and distribution of bioconjugated QDs in single living cells. Such QDs nanoplatform can be further modified for developing biomedical evaluation tool in cancer diagnosis and targeted drug delivery. 展开更多
关键词 Confocal microscopy Drug delivery Three dimensional
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印度拉贾斯坦邦半干旱地区流域发展项目对农业经济的影响
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作者 Ashok Kumar S.V.Singh +1 位作者 K.D.Singh S.n.prasad 《中国水土保持》 北大核心 2002年第7期42-43,共2页
关键词 印度 拉贾斯坦邦半干旱地区 流域发展项目 农业经济
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捣固焦炭不整粒的可能性 被引量:1
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作者 H.n.prasad 卢树忠 《燃料与化工》 2000年第3期162-165,共4页
关键词 捣固焦炭 焦炭 不整粒
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奥氏体化温度对耐候钢组织和性能的影响
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作者 S.nprasad S.R.Mdiratta +1 位作者 D.S.Sarma 柴海涛(译) 吴光亮(校正) 《涟钢科技与管理》 2008年第2期57-64,共8页
耐候钢属于低合金高强度钢(HSLA),常用的合金元素有Cu、P、Cr、和Ni。当不加磷时,用V(0.04%)的析出强化来弥补磷强烈固溶强化的损失。这些合金元素有两方面的作用,一方面是形成保护层阻止钢腐蚀,另一方面是增加钢的硬度和强... 耐候钢属于低合金高强度钢(HSLA),常用的合金元素有Cu、P、Cr、和Ni。当不加磷时,用V(0.04%)的析出强化来弥补磷强烈固溶强化的损失。这些合金元素有两方面的作用,一方面是形成保护层阻止钢腐蚀,另一方面是增加钢的硬度和强度。耐候钢具有广泛的用途,如制造铁道车辆、货车、容器、桥梁、转播塔等等。 展开更多
关键词 耐候钢 奥氏体化温度 组织和性能 低合金高强度钢 合金元素 固溶强化 析出强化 铁道车辆
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颗粒间相互作用对宽浅坡面流输移能力影响的试验观测
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作者 Shyam n.prasad S.Madhusudana Rao Mathias J.M.Romkens 《人民黄河》 CAS 北大核心 2005年第11期69-69,共1页
流域上游地区的土壤侵蚀及与其相关的泥沙运移是影响流域地表径流水质的重要过程,被侵蚀的泥沙大部分由坡面流输移,目前的泥沙输移关系都是从剪切力概念或河道能量概念引出的,而这些概念却都是仅仅基于流体力学的。泥沙的运移都单一... 流域上游地区的土壤侵蚀及与其相关的泥沙运移是影响流域地表径流水质的重要过程,被侵蚀的泥沙大部分由坡面流输移,目前的泥沙输移关系都是从剪切力概念或河道能量概念引出的,而这些概念却都是仅仅基于流体力学的。泥沙的运移都单一地依赖于水流剪切力或能量的阈值条件,这一理论的前提是:①泥沙初始运移需要的最小剪切力或临界剪切力,或者最小、临界河道能量;②泥沙输移率和剪切力或河道能量与其临界值的差值密切相关。这些关系或许可以用来描述泥沙在河道中的输移,却不能反映出泥沙在宽浅坡面流中输移的微观机制或物理过程。流域的上游地区,在上临界弗如德数的水力条件下,坡面流含沙量的变化范围非常大。在宽浅坡面流的试验研究中,泥沙按照逐步控制方式添加到坡面流中,并且通过测量来确定颗粒速度与含沙量之问的关系。在不同的水力条件下,存在最大的泥沙输移率,对泥沙颗粒运移的观测表明:泥沙输移方式是跳跃式的,在这些条件下,水流状态受控于包含了很大部分动能的滚动波,因此滚动波是薄层流泥沙侵蚀及输移过程中的主要能量来源。 展开更多
关键词 泥沙输移 试验观测 颗粒间相互作用 坡面流 泥沙运移 能量概念 能力 土壤侵蚀 上游地区 水力条件
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地表土壤动力封闭条件下的入渗研究
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作者 S.n.prasad M.J.M.Rmkens 《中国水土保持》 北大核心 2002年第7期19-19,共1页
关键词 降水 土壤密闭 土壤介质 水分入渗 浅流方程
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Localization of polycyclic aromatic hydrocarbons and heavy metals in surface soil of Asia’s oldest oil and gas drilling site in Assam,northeast India:Implications for the bio-economy 被引量:3
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作者 Hemen Sarma n.F.Islam +2 位作者 P.Borgohain A.Sarma M.n.V.prasad 《Emerging Contaminants》 2016年第3期119-127,共9页
The environmental influx of hazardous contaminants viz PAHs and HMs occurs due to oil and gas drilling,and processing of petroleum products in industrial facilities and refineries.This problem plagues crude oil drilli... The environmental influx of hazardous contaminants viz PAHs and HMs occurs due to oil and gas drilling,and processing of petroleum products in industrial facilities and refineries.This problem plagues crude oil drilling sites as PAHs are an essential component of and HMs coexist with crude oil.We analyzed the spatial distribution of 16 PAHs and 8 HMs in 10 contaminated sites of Assam,a state in India.These included Digboi,where crude oil was drilled in 1867 and the first oil well in Asia that was drilled.TheƩ16 PAHs in soil were detected with a minimum of 13.48 and a maximum of 86.3 mgkg1 andƩ8 heavy metal concentrations in the soil ranged between 69.51 and 336.06 mgkg1.A negative correlation was detected between the relative concentrations of PAHs and HMs.The results confirmed that the nonbiodegradable nature of HMs made them stay in the soil for longer periods of time.In our study,we found that the levels of lead,copper,nickel,and chromium(total)in soil were 73.62,11.86,58.97 and 158.66 mgkg1.The recovery percentage for PAHs and HMs were in the range of 67e97%and 90e95%respectively.Spatial distribution indices for Phenanthrene/Anthracene,Naphthalene/Acenapthhylene,Chyrsene/Benzo(g,h,i)perylene and Fluranthene/Pyrene)calculated for soil samples indicated that the spatial distribution of PAHs in soil is uneven which might be due to variations in contaminates disseminated in soil.Such regionalized concentration has serious implications on the bio-economy both in terms of health and economy,especially since the proximity of crude oil sites to paddy fields and/or tea plantations uniquely marks the landscape of upper Assam. 展开更多
关键词 PAH Heavy metals Spatial distribution indices Oil Drilling site
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