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Effect of process parameter on the flowability of nanocrystalline CoNiCrAlY powder synthesized by mechanical milling

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Particuology 2024年第9期92卷 210-223页

作者： Annadaa Shankara Dash Indranil Manna Deepa Devapal sharad chandra sharma Jyotsna Dutta Majumdar School of Nanoscience and Technology IIT KharagpurWest BengalIndia BIT Mesra RanchiJharkhandIndia Department of Metallurgical and Materials Engineering IIT KharagpurWest BengalIndia Vikram Sarabhai Space Centre ThiruvanthapuramKeralaIndia

The present study concerns understanding the effect of process parameters on the characteristics and flowability of nanocrystalline CoNiCrAlY powder synthesized by mechanical *** milling has been conducted in a planetary ball mill with tungsten carbide(WC)ball,with ball to powder ratio of 10:1 at 300 rpm speed,using 1%stearic acid and toluene as process control agent(PCA)with time varying from 10 h to 36 *** synthesized nanocrystalline powder were characterized by Scanning Electron Microscopy,X-ray Diffraction technique,X-ray Photoelectron Spectroscopy,and Differential Scanning ***,flowability in terms of Hausner ratio was assessed by Tap Density *** particle size of the powder was found to decrease from 33μm to 22μm after 10 h of milling and further increases to 43μm and 38μm after 25 and 36 h of milling,respectively,in stearic acid ***,in toluene medium particle size continuously decreases from 33μm to 9.7μm with increasing milling *** particle morphology changes from spherical to platelet shape at low milling hours in both of the *** 25 h of milling,the shape of the particles is nearly spherical for stearic acid and irregular for toluene used as a *** size was found to decrease with increasing milling time from 147 nm to 7.7 nm and to 6.4 nm in stearic acid and toluene media,*** was presence ofγ,γʹ,β,hcp-Co,Al_(2)O_(3)and AlOOH phases on the powder particles milled in both the *** measured Hausner ratio of the powders was found to vary from 1.18 to 1.32 in stearic acid medium,and was found to increase with increasing milling *** the other hand,in toluene media flowability decreases(Hausner ratio increases from 1.33 to 1.44)with increasing milling time.

关键词： Mechanical milling Microstructure Process control agent(PCA) CoNiCrAIY Toluene Stearic acid Flowability

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自由取向炭/炭复合材料的新型制备及工艺优化（英文）

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新型炭材料 2018年第5期33卷 424-433页

作者： Thakur Sudesh Kumar Raunija Rajeev K.Gautam sharad chandra sharma Anil Verma Carbon and Ceramics Laboratory Materials and Mechanical EntityVikram Sarabhai Space Centre Indian Space Research OrganisationThiruvananthapuram 695022KeralaIndia Sustainable Environergy Research Lab(SERL) Department of Chemical Engineering Indian Institute of Technology DelhiHauz-KhasNew Delhi 110016India Materials and Metallurgy Group Materials and Mechanical EntityVikram Sarabhai Space Centre Indian Space Research OrganisationThiruvananthapuram 695022KeralaIndia

采用在炭纤维束的内部浸润熔融沥青的传统方法制备得到的炭/炭(C/C)复合材料难以实现细旦化水平,这是因为单束丝中含有数千根丝,经浸渍后沥青附着,从而引起沥青局部渗出,以及因不均匀沥青稳定性而导致微观结构不均匀。本文通过稳定的中... 详细信息

采用在炭纤维束的内部浸润熔融沥青的传统方法制备得到的炭/炭(C/C)复合材料难以实现细旦化水平,这是因为单束丝中含有数千根丝,经浸渍后沥青附着,从而引起沥青局部渗出,以及因不均匀沥青稳定性而导致微观结构不均匀。本文通过稳定的中间相沥青和分散的短切炭纤维混合、热压和炭化过程制备出细旦化水平的C/C复合材料。探讨了工艺参数对中间相沥青残炭率的影响。通过残炭率/工艺时间、残炭率!(表观密度/实密度)来优化工艺参数。结果表明,通过此法得到了细旦化水平的中间相沥青与炭纤维复合材料。中间相沥青的残炭率随加热升温速率、沥青/炭纤维质量比的增加而降低;随热压压力而增加。在高压力和高质量比下,发生沥青局部渗出。通过调控得到最佳的C/C复合材料制备工艺参数为:热压压力15 MPa,升温速率0. 2℃/min及沥青/炭纤维质量比1∶1。

关键词：石油沥青中间相沥青短切炭纤维热压产率

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Fabrication of Self-cleaning Antireflective Polymer Surfaces by Mimicking Underside Leaf Hierarchical Surface Structures

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Journal of Bionic Engineering 2019年第3期16卷 400-409页

作者： Srinadh Mattaparthi chandra Shekhar sharma Creative & Advanced Research Based on Nanomaterials (CARBON) Laboratory Department of Chemical Engineerings Indian Institute of Technology Hyderabad Kandi Telangana 502285 India

In this work, we utilized underside of four different plant leaves with different scale of hierarchical surface roughness to fabricate large area self-cleaning antireflective polymer surfaces. A simple and precise two-step soft-lithography replica molding technique was deployed by using polydimethylsiloxane (PDMS) polymer as a replicating material. In the first step, a negative PDMS replica was fabricated by using the underside of an original leaf as a template material. In the second step, a positive PDMS replica was fabricated through a negative PDMS replica used as a template. In order to study the non-wetting and light trapping properties, as-replicated polymer surfaces were characterized using Scanning Electron Microscopy (SEM), contact angle goniometer, and UV-Vis spectroscopy. SEM images confirmed the successful replication of complex hierarchical structures while contact angle measurement studies established retaining high non-wetting properties in polymer replicas. Optical studies suggest near zero reflection in normal mode and less than 5% diffuse reflection when measured using integrated sphere mode. These results have been correlated and explained with the air-liquid fraction and roughness factor as measured using three-dimensional optical profilometer.

关键词： biomimicking natural leaf replica molding non-wetting light trapping hierarchical roughness

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Ethanol steam reforming study over ZSM-5 supported cobalt versus nickel catalyst for renewable hydrogen generation

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Chinese Journal of Chemical Engineering 2019年第3期27卷 677-684页

作者： Ashutosh Kumar Ram Prasad Yogesh chandra sharma Department of Chemistry Indian Institute of Technology (Banaras Hindu University) Varanasi Department of Chemical Engineering & Technology Indian Institute of Technology (Banaras Hindu University) Varanasi

The renewable hydrogen generation through ethanol steam reforming is one of the anticipated areas for sustainable hydrogen generation. To elucidate the role of Ni and Co with ZSM-5 support, catalysts were prepared by wet impregnation method and ethanol steam reforming(ESR) was performed. The catalysts were characterized by HR-XRD, ATR–FTIR, HR-SEM, TEM with SAED, EDAX, surface area analyzer and TPR. It had shown complete ethanol conversion at 773 K, but the selectivity in hydrogen generation was found higher for 10% Ni/ZSM-5 catalyst as compared to 10% Co/ZSM-5. The 10% Ni/ZSM-5 catalyst has about 72% hydrogen selectivity at temperature 873 K. It indicates that Ni is a more sustainable catalyst as compared to Co with ZSM-5 support for ESR. The C_2H_4 was found major undesirable products up to 823 K temperature. Nevertheless, the 10% Ni/ZSM-5 catalyst had shown its stability for high temperature(873 K) ESR performance.

关键词： Ethanol steam reforming Zeolite Hydrogen Renewable energy Catalyst

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Some Observations about the MOLSCAT

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Communications in Theoretical Physics 2015年第12期64卷 731-734页

作者： Mohit Kumar sharma Monika sharma Suresh chandra School of Studies in Physics Jiwaji University Physics Department Lovely Professional University

For calculation of cross sections for collisional transitions between rotational levels in a molecule,a computer code,MOLSCAT is *** the transitions between rotational levels in H_2 CS due to collisions with He atom,we have calculated cross sections under the CS approximation,for example,for total energy 11 cm^(-1).The calculations have been done for the single energy 11 cm"1 and for ten *** have found that the cross sections for the single energy 11 cm^(-1),differ from those in the first seven combinations,but are in agreement with those in the last three *** reason for the difference in the results appears that the MOLSCAT uses the intermediate data of calculations for one energy,in the calculations for other *** agreement with the last three combinations may be understood that when the energy of combination is in the decreasing trend,the cross sections for the first(common)energy are *** may be suggested to run the MOLSCAT for a single energy at a time.

关键词： ISM: molecules collisional transitions MOLSCAT

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Wind pollination in Pinus roxburghii

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Progress in Natural Science:Materials International 2007年第1期17卷 32-38页

作者： Vinod Prasad KHANDURI chandra Mohan sharma Department of Forestry Mizoram University Aizawl(Mizoram)India Department of Forestry HNB Garhwal University Srinagar Garhwal-246 174(Uttaranchal)India

Stigmatic pollen load and pollen concentration in the air were studied in the natural population of Pinus roxburghii at Ashtavakra (900 m asl), in the Pauri forest division of Garhwal Himalaya, India. The results reflect diurnal pollen occurrence in P. roxburghii , with the strong significant correlations between pollen concentrations in the air and wind speed, air temperature and relative air humidity. A significant correlation was also observed between microsporangium dehiscence and pollen occurrence in the air. The maximum concentration of pollen grains in the air and higher rates of pollen deposition onto the megasporophylls were between 12 pm and 16 pm of the day, which conforms the best time for pollination in a day in P. roxburghii. The receptivity of Ovulate strobili varied from 3 to 5 days, however, the bagged strobili remained receptive up to 6 days.

关键词： ovulate strobili pollen cones pollination receptivity wind speed P. roxburghii.

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MOLECULAR DYNAMICS SIMULATION OF POLYMER/CARBON NANOTUBE COMPOSITES

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Acta Mechanica Solida Sinica 2015年第4期28卷 409-419页

作者： Sumit sharma Rakesh chandra Pramod Kumar Navin Kumar Department of Mechanical Engineering Dr.B.R.Ambedkar National Institute of Technology School of Mechanical Materials & Energy Engineering (SMMEE) Indian Institute of Technology

In this paper, we present classical molecular dynamics （MD） simulations of model polymer/CNT composites constructed by embedding a single wall （10,10） CNT into two different amorphous polymer matrices： poly（methyl methacrylate） and poly{（m-phenylene-vinylene）-co- [（2,5-dioctoxy-p-phenylene） vinylene]}, respectively, with different volume fractions. The simulation results support the idea that it is possible to use CNTs to mechanically reinforce an appropri- ate polymer matrix, especially in the longitudinal direction of the nanotube. The comparison of the simulation results with the macroscopic rule-of-mixtures for composite systems showed that for strong interfacial interactions, there can be large deviations of the results from the rule-of- mixtures. In order to verify this study, results obtained have been compared with those given by Elliott and Han （2007）.

关键词： nano-structures elasticity mechanical properties computational modeling

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Strategies to mitigate the adverse effect of drought stress on crop plants-influences of soil bacteria:A review

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Pedosphere 2021年第3期31卷 496-509页

作者： Priyanka chandra Amoolya WUNNAVA Pooja VERMA Amaresh chandra Rakesh Kumar sharma Indian Council of Agricultural Research(ICAR) Central Soil Salinity Research InstituteKarnalHaryana 132001India Department of Biosciences Manipal University JaipurRajasthanJaipur 303007India Indian Council of Agricultural Research(ICAR) Indian Institute of Sugarcane ResearchUttar PradeshLucknow 226002India

Drought stress affects plant growth and causes significant issues in meeting global demand for food crops and *** can cause physiological,physicochemical,and morphological changes in plants,which negatively affects plant growth and *** combat this under the increasing global threat of water shortage and rapid population expansion,it is crucial to develop strategies to meet global food *** growth-promoting rhizobacteria(PGPR)may provide a safe solution to enhancing crop yields through various *** soil bacteria can provide drought tolerance to crop plants,allowing them to survive and thrive in water-scarce *** of phytohormones,free radical-scavenging enzymes,and stress-combating enzymes that can increase tolerance to drought-induced stress are key features of plant-associated microbial *** review summarizes the beneficial properties of microbes that help plants tolerate water scarcity and highlights the bacterial mechanisms that enhance drought tolerance in plants.

关键词： abiotic stress agricultural yield drought tolerance food crops microbe PGPR rhizobactoria water deficit

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Gender plasticity uncovers multiple sexual morphs in natural populations of Cedrus deodara (Roxb.) G. Don

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Ecological Processes 2021年第1期10卷 459-469页

作者： Vinod Prasad Khanduri Arun Sukumaran chandra Mohan sharma Department of Forestry College of ForestryVCSG Uttarakhand University of Horticulture and ForestryRanichauriTehri GarhwalUttarakhand 249199India Present Address:State Farming Corporation of Kerala Chithalvetty EstateKalanjoor KollamKeralaIndia.

Background:The expression of gender in gymnosperms is challenging because the extent of variability in gender segregations in tree crowns and selection pressure of nature can modify the gender through ***:An in-depth investigation on spatial segregation of genders in tree crowns and sex expression of a total of 500 trees in five different natural populations of Cedrus deodara was carried out and verified the occurrence of subdioecious(co-existence of male,female,and monoecious)genders in ***:Five different sexual morphs were apparent among the 500 selected individuals as(1)pure male(M):bearing only male strobili in the whole crown with 22.2%;(2)pure female(F):bearing only female strobili in the whole crown with 12.4%;(3)mixed-monoecious(MM):bearing both male and female strobili with 13.6%;(4)predominantly female(PF)with 25.6%;and(5)predominantly male(PM)with 26.2%.The occurrence of multiple sexual morphs resulted from the complex selection pressure,which increased the stability of the *** segregation of genders in crown layers deemed to increase the fitness that may be a mechanism for accelerating *** results of the study suggest that the subdioecious gender expression in *** is evolved through the monoecy–paradioecy *** production of male strobili revealed non-significant effect of tree sizes whereas a significant effect was observed for the production of female *** study established that the total pollen and seed outputs in *** changed frequently according to gender ***:The size of the tree,resource availability,sex allocation,plant architecture,gender segregation in crowns,and habitat conditions are the prominent causes for gender plasticity.

关键词： Gender Sex expression Gender segregation Strobili Pre-fertilisation Monoecy Dioecy

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Pollinator-mediated self-pollination and reproductive assurance in an isolated tree of Magnolia grandiflora L.

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Ecological Processes 2020年第1期9卷 517-525页

作者： Arun Sukumaran Vinod Prasad Khanduri chandra Mohan sharma College of Forestry VCSG Uttarakhand University of Horticulture and ForestryRanichauriTehri GarhwalUttarakhand 249199India

Background:The ability to produce seeds when pollinators or potential mates are scarce is one of the principal advantages of self-pollination in flowering ***,the role of pollinators mediating self-pollination to ensure seed set when pollen or potential mates are limited has received less *** study examined the reproductive consequences and involvement of pollinators in assuring seed set in an isolated tree of Magnolia grandiflora,a predominantly outcrossing ***:We tested various aspects of reproduction such as flower density,floral rewards,stigma receptivity,pollinator abundance and behaviour,fruit set and seed set,in two successive reproductive years(2015-2016).Results:Flowers of *** possess a suite of traits facilitating pollinator-mediated self-pollination(PMS),although the chances of autonomous self-pollination are reduced due to herkogamy,spatial separation of anther and *** mean pollen production/flower was 5,152,289±285,094 with a pollen-to-ovule ratio of 39430±*** found a significant positive correlation between number of visits and seed production for bees(r=0.5099,p=0.0007)and beetles(r=0.7159,p=0.00001),indicating these are effective at *** was a significant negative correlation for thrips(r=-0.3206,p=0.044)and no correlation for flies or *** percent fruit set was 100%and the seed set per ovule ranged between 19 and 20%.Conclusions:PMS will guarantee reproductive assurance and mitigate the effect of reduced mates or pollen limitation which is expected to increase the fecundity and establishment of individual trees in geographically isolated locations.

关键词： Pollinator-mediated self-pollination Magnolia grandiflora Autonomous self-pollination Pollinator behaviour Reproductive assurance

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