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半导体量子棒的光控取向技术进展

液晶与显示 2020年第5期35卷 409-421页

作者：张万隆 srivastava abhishek ROGACH Andrey 郭海成香港科技大学先进显示与光电子技术国家重点实验室香港999077 香港城市大学功能光子研究中心香港999077

介绍了液晶分子的光控取向技术和半导体量子棒均匀定向的方法。该方法可以将高亮度、核/壳结构的CdSe/CdS量子棒与液晶单体相互结合,通过定向排列液晶单体来实现对量子棒的定向排列,并利用紫外光聚合固化,形成包裹量子棒的液晶聚合物薄... 详细信息

介绍了液晶分子的光控取向技术和半导体量子棒均匀定向的方法。该方法可以将高亮度、核/壳结构的CdSe/CdS量子棒与液晶单体相互结合,通过定向排列液晶单体来实现对量子棒的定向排列,并利用紫外光聚合固化,形成包裹量子棒的液晶聚合物薄膜。通过对高偏振荧光量子棒的光学表征,展现出高排列序参数。在应用方面,液晶聚合物中的量子棒可在微米尺度(低至2μm)内进行多畴取向,展现出在光子学和保密领域中的应用前景;结合量子棒/液晶聚合物(QR/LCP)薄膜与液晶显示技术,可用于新式光学驱动荧光显示设备;用于现代液晶显示设备中的量子棒亮度增益膜,在增强色彩表现(>100%NTSC)的同时,又能提高显示器的光学效率(>8%)。

关键词：半导体量子棒光控取向偏振荧光液晶多畴取向

Kerr effect and Kerr constant enhancement in vertically aligned deformed helix ferroelectric liquid crystals

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Chinese Physics B 2016年第9期25卷 9-12页

作者： Liangyu Shi abhishek Kumar srivastava Vladimir G Chigrinov Hoi-Sing Kwok State Key Laboratory on Advanced Displays and Optoelectronics Technologies Hong Kong University of Science and Technology

In this article,we review recently achieved Kerr effect progress in novel liquid crystal（LC） material：vertically aligned deformed helix ferroelectric liquid crystal（VADHFLC）.With an increasing applied electric field,the induced inplane birefringence of LCs shows quadratic *** theoretical calculations and experimental details are *** an enhanced Kerr constant to 130 nm/V2,this VADHFLC cell can achieve a 2π modulation by a small efficient electric field with a fast response around 100 μs and thus can be employed in both display and photonics devices.

关键词： Kerr effect deformed helix ferroelectric liquid crystal phase modulation of light

Use of a Bioaugmented Organic Soil Amendment in Combination with Gypsum for Withania somnifera Growth on Sodic Soil

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Pedosphere 2016年第3期26卷 299-309页

作者： Manjul GUPTA Pankaj Kumar srivastava SHIKHA abhishek NIRANJAN Shri Krishna TEWARI CSIR National Botanical Research Institute Rana Pratap Marg Lucknow 226001 (India) School of Environmental Sciences Babasaheb Bhimrao Ambedkar University Vidya Vihar Rae Bareilly Road Lucknow 226025 (India)

Limited availability of organic matter is a problem to sustain crop growth on sodic soil. Organic soil amendments are a costeffective source of nutrients to enhance crop growth. A field study was conducted to evaluate the effect of an organic soil amendment bioaugmented with plant growth-promoting fungi(SF_(OA) ) in combination with gypsum on soil properties and growth and yield attributes of Withania somnifera, one of the most valuable crops of the traditional medicinal system in the world, on a sodic soil at the Aurawan Research Farm of CSIR-National Botanical Research Institute, Lucknow, India. The SF_(OA) used was prepared by pre-enriching farm waste vermicompost with plant growth-promoting fungi before mixing with pressmud and Azadirachta indica seed cake. The application of SF_(OA) at 10 Mg ha^(-1)after gypsum(25.0 Mg ha^(-1)) treatment significantly(P < 0.05) increased root length(by 96%) and biomass(by 125%) of Withania plants compared to the control without SF_(OA) and gypsum. Similarly, the highest withanolide contents were observed in leaves and roots of Withania plants under 10 Mg ha^(-1)SF_(OA) and gypsum. Combined application of SF_(OA) and gypsum also improved physical, chemical and enzymatic properties of the soil, with the soil bulk density decreasing by 25%, water-holding capacity increasing by 121%, total organic C increasing by 90%, p H decreasing by 17% and alkaline phosphatase, β-glucosidase, dehydrogenase and cellulase activities increasing by 54%, 128%, 81% and 96%, respectively, compared to those of the control. These showed that application of the SF_(OA) tested in this study might reclaim sodic soil and further support Withania cultivation and results were better when the SF_(OA) was applied after gypsum treatment.

关键词： medicinal crop plant growth-promoting fungi soil property soil reclamation vermicompost

Superpenumbral chromospheric flare

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Research in Astronomy and Astrophysics 2018年第10期18卷 131-140页

作者： Suo Liu Hong-Qi Zhang Debiprasad P.Choudhary abhishek K.srivastava Bhola Nath Dwivedi National Astronomical Observatories Chinese Academy of Sciences Department of Physics and Astronomy California State University Department of Physics Indian Institute of Technology (BHU)

We observed a C-class flare at the outer boundary of the superpenumbra of a sunspot. The flare was triggered by an emerging magnetic bipolar region that was obliquely oriented with respect to the superpenumbral fibrils. The flare started due to the low height magnetic reconnection of emerging magnetic flux with a superpenumbral field resulting in hot multi-temperature plasma flows in the inverse Evershed flow channel and its overlying atmosphere. Inverse Evershed flows in the chromosphere start from the superpenumbra towards the sunspot that end at the outer boundary of the penumbra. The hot plasma flow towards the sunspot in the inverse Evershed channels show about 10 km s^-1 higher velocity in Ha wavelengths compared to the plasma emissions at various temperatures as seen in different AIA filters. Even though these velocities are about seven times higher than the typical inverse Evershed flow speeds, the flow is diminished at the outer boundary of the sunspot＇s penumbra. This suggests that the superpenumbral field lines that carry inverse Evershed flows are discontinued at the boundary where the penumbral field lines dive into the sun and these two sets of field lines are completely distinct. The discontinuity in the typical magnetic field and plasma properties at the adjoining of these two sets of field lines further leads to discontinuity in the characteristic magnetoacoustic and Alfvrn speeds, thereby stopping the plasma flows further on. The multi-temperature plasma in the inverse Evershed channels exhibits possible longitudinal oscillations initially during the onset of the flare, and later flows towards the sunspot. In the multi-temperature view, the different layers above the flare region have a mixture of supersonic as well as subsonic flows.

关键词： magnetic field solar flare trigger magnetic emergence

MHD Seismology of a loop-like filament tube by observed kink waves

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Research in Astronomy and Astrophysics 2015年第10期15卷 1713-1724页

作者： Vaibhav Pant abhishek K srivastava Dipankar Banerjee Marcel Goossens Peng-Fei Chen Navin Chandra Joshi Yu-Hao Zhou Indian Institute of Astrophysics Department of Physics Indian Institute of Technology(BHU) Center of Excellence in Space Sciences Centre for Mathematical Plasma Astrophysics Department of Mathematics School of Astronomy and Space Science Nanjing University Key Lab of Modern Astronomy and Astrophysics Nanjing University School of Space Research Kyung Hee University

We report and analyze observational evidence of global kink oscillations in a solar filament as observed in Ha by instruments administered by National Solar Observatory （NSO）/Global Oscillation Network Group （GONG）. An M1.1-class flare in active region （AR） 11692 occurred on 2013 March 15 and induced a global kink mode in the filament lying towards the southwest of AR 11692. We find periods of about 61-67 minutes and damping times of 92-117 minutes at positions of three ver- tical slices chosen in and around the filament apex. We find that the waves are damped. From the observed period of the global kink mode and damping timescale using the theory of resonant absorption, we perform prominence seismology. We estimate a lower cut-off value for the inhomogeneity length scale to be around 0.34-0.44 times the radius of the filament cross-section.

关键词： Sun: oscillations -- Sun: magnetic fields -- Sun: filament

Unidirectionally aligned bright quantum rods films,using T-shape ligands,for LCD application

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Nano Research 2022年第6期15卷 5392-5401页

作者： Maksym F.Prodanov Chengbin Kang Swadesh K.Gupta Valerii V.Vashchenko Yuhao Li Minchao Qin Xinhui Lu abhishek K.srivastava State Key Laboratory of Advanced Displays and Optoelectronics Technologies and Centre for Display Research Department of Electronics and Computer EngineeringThe Hong Kong University of Science and TechnologyClear Water BayHong Kong 999077Hong KongChina Department of Physics The Chinese University of Hong KongShatinHong Kong 999077Hong KongChina

Unidirectionally aligned nanorods(NRs)are of great importance for different applications,including displays,lighting,and ***,many alignment techniques were studied to align quantum rods(QRs).However,the brightness of these films,due to the limited concentration of aligned quantum rods in the film,is not enough for their implementation as brightness enhancement films(BEFs)in *** can be ascribed to the poor miscibility of quantum rods in polymer and strong concentration dependence of the polarized *** ligands of NR are very important for the alignment and *** this article,we proposed a ligand combination comprising T-shape promesogenic phosphonic acid,which on being photoaligned provides mutually parallel alignment of the quantum *** T-shape ligands enable the fabrication of hybrid films with a QRs concentration as high as 10 wt.%–20 wt.%retaining high brightness and luminescence polarization ***,we used these films in the in-plane switching(IPS)display backlight that shows the color gamut up to 121%of national television system committee(NTSC)(CIE1931),liquid-crystal display(LCD)efficiency up to 7.9%,power efficacy 103±2 nits/W,and the high brightness of~550±10 ***,the proposed ligands can be used for the alignment of a variety of nanorods.

关键词： quantum rods(QRs) ligands alignment display luminous efficiency

Photo-induced flexible semiconductor CdSe/CdS quantum rods alignment

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Journal of Semiconductors 2023年第9期44卷 83-89页

作者： Wanlong Zhang Julian Schneider Maksym F.Prodanov Valerii V.Vashchenko Andrey L.Rogach Xiaocong Yuan abhishek K.srivastava Nanophotonics Research Center Institute of Microscale OptoelectronicsShenzhen UniversityShenzhen 518060China State Key Laboratory of Advanced Displays and Optoelectronics Technologies Department of Electronic&Computer EngineeringHong Kong University of Science and TechnologyHong Kong SARChina Department of Materials Science and Engineering and Centre for Functional Photonics(CFP) City University of Hong KongHong Kong SARChina

The anisotropic absorption and emission from semiconductor CdSe/CdS quantum rods(QRs)provide extra benefits among other photoluminescence *** photo-induced alignment technique,the QRs can be oriented in liquid crystal polymer matrix at a large *** this article,a 2D Dammann grating pattern,within“SKL”characters domains aligned QRs in composite film,was fabricated by multi-step photo exposure using several photo masks,and a continuous geometric lens profile pattern aligned QRs was realized by the single step polarization converting holographic irradiation *** polarized optical microscope and fluorescence microscope are employed to determine the liquid crystal director profiles and QRs anisotropic excitation *** have been able to orient the QRs in fine binary and continuous patterns that confirms the strong quantum rod aligning ability of the proposed ***,the proposed approach paves a way for photoinduced flexible QRs alignments to provide a highly specific and difficult-to-replicate security application at a large scale.

关键词： quantum rods photo alignment liquid crystal flexible alignment polarized emission

Artificial Neural Network Modeling for Sorption of Cadmium from Aqueous System by Shelled Moringa Oleifera Seed Powder as an Agricultural Waste

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Journal of Water Resource and Protection 2010年第4期2卷 339-344页

作者： abhishek Kardam Kumar Rohit Raj Jyoti Kumar Arora Man Mohan srivastava Shalini srivastava 不详

A two-layer Artificial Neural Network (ANN) model was developed to predict the removal efficiency of Cd(II) ions from aqueous solution using shelled Moringa Oleifera seed (SMOS) powder. Batch experiments re-sulted into standardization of optimum conditions: biomass dosage (4.0 g), Cd(II) concentration (25 mg/L) volume (200 mL) at pH 6.5. A time of forty minutes was found sufficient to achieve the equilibrium. The ANN model was designed to predict sorption efficiency of SMOS for target metal ion by combining back propagation (BP) with principle component analysis. A sigmoid axon was used as transfer function for input and output layer. The Levenberg-Marquardt algorithm (LMA) was applied, giving a minimum mean squared error (MSE) for training and cross validation at the ninth place of decimal.

关键词： Artificial Neural Network Biosorption SMOS Cd(II) Removal

Neural Network Modeling for Ni(II) Removal from Aqueous System Using Shelled Moringa Oleifera Seed Powder as an Agricultural Waste

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Journal of Water Resource and Protection 2010年第4期2卷 331-338页

作者： Kumar Rohit Raj abhishek Kardam Jyoti Kumar Arora Man Mohan srivastava Shalini srivastava 不详

A single-layer Artificial Neural Network (ANN) model was developed to predict the removal efficiency of Ni(II) ions from aqueous solution using shelled Moringa Oleifera seed (SMOS) powder. Batch experiments resulted into standardization of optimum conditions: biomass dosage (4.0 g), Ni(II) concentration (25 mg/L) volume (200 mL) at pH 6.5. A time of forty minutes was found sufficient to achieve the equilibrium. The ANN model was designed to predict sorption efficiency of SMOS for target metal ion by combining back propagation (BP) with principle component analysis. A sigmoid axon was used as transfer function for input and output layers. The Levenberg–Marquardt Algorithm (LMA) was applied, giving a minimum mean squared error (MSE) for training and cross validation at the ninth place of decimal.

关键词： Artificial Neural Networks Biosorption Moringa Oleifera Ni(II) Removal