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Phase constitution of the noble metal thin-film complex solid solution system Ag-Ir-Pd-Pt-Ru in dependence of elemental compositions and annealing temperatures

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Nano Research 2022年第6期15卷 4827-4836页

作者： Bin Xiao Xiao Wang Alan savan Alfred Ludwig Materials Discovery and Interfaces Institute for MaterialsRuhr University Bochum44780 BochumGermany Zentrum für Grenzflächendominierte Höchstleistungswerkstoffe(ZGH) Ruhr University Bochum44780 BochumGermany

Multiple-principal element alloys hold great promise for multifunctional material discovery(e.g.,for novel electrocatalysts based on complex solid solutions)in a virtually unlimited compositional ***,the phase constitution of the noble metal system Ag-Ir-Pd-Pt-Ru was investigated over a large compositional range in the quinary composition space and for different annealing temperatures from 600 to 900°C using thin-film materials ***-dependent X-ray diffraction mapping of the asdeposited thin-film materials library indicates different phases being present across the composition space(face-centered cubic(fcc),hexagonal close packed(hcp)and mixed fcc+hcp),which are strongly dependent on the Ru *** general,low Ru contents promote the fcc phase,whereas high Ru contents favor the formation of an hcp solid-solution ***,a temperature-induced phase transformation study was carried out for a selected measurement area of fcc-Ag_(5)Ir_(8)Pd_(56)Pt_(8)Ru_(23).With increasing temperature,the initial fcc phase transforms to an intermediate C14-type Laves phase at 360°C,and then to hcp when the temperature reaches 510°*** formation and disappearance of the hexagonal Laves phase,which covers a wide temperature range,plays a crucial role of bridging the fcc to hcp phase *** obtained composition,phase and temperature data are transformed into phase maps which could be used to guide theoretical studies and lay a basis for tuning the functional properties of these materials.

关键词： noble metal high-entropy alloys phase transformation combinatorial synthesis and high-throughput characterization

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Scrupulous recognition of biologically important acids by fluorescent ＂turn off-on＂ mechanism of thaicalix reduced silver nanoparticles

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Chinese Chemical Letters 2017年第2期28卷 312-318页

作者： savan M.Darjee keyur D.Bhatt Urvi S.Panchal Vinod k.Jain Department of Chemistry School of Sciences Gujarat University Ahmedabad 380009 India Department of Chemistry C.U. Shah University Wadhwan 363030 India

Water dispersible silver nanoparticles（AgNps） were prepared using thiacalix[4]arene tetrahydrazide（TCTH） as a reducing and stabilizing ***-AgNps were characterized by surface plasmon resonance（SPR）,transmission electron microscopy（TEM） and energy dispersive X-ray（EDX）.Relatively uniform 20 nm spherical particles of TCTH-AgNps were efficiently formed over a pH range of 5-9 and from 10-40 ℃.The interaction behavior of TCTH-AgNps with different amino acids was investigated using spectrophotometry and *** the amino acids tested,only tryptophan and histidine showed fluorescence quenching and fluorescence enhancement,*** linear detection range by Stern-Volmer plot was 5 nmol/L to 0.48 μmol/L for tryptophan and 4 nmol/L to 0.54 μmol/L for ***-AgNps were able to effectively reduce the levels of gram-positive bacteria,gram-negative bacteria,and *** properties argue for the potential use of TCTH-AgNps as detectors of histidine and tryptophan and as antibiotics.

关键词： Silver nanoparticles Fluorescent sensor Colorimetric sensor Thiacalixarene

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Synthesis,optimization and characterization of biochar based catalyst from sawdust for simultaneous esterification and transesterification

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Chinese Journal of Chemical Engineering 2018年第12期26卷 2654-2663页

作者： Suchith Chellappan Vaishakh nair Sajith V. Aparna k. Department of Chemical Engineering National Institute of TechnologyCalicut India Institute of Physical Chemistry Polish Academy of Sciences School of Nano Science and Technology National Institute of Technology

The development of a benign environmental catalyst for the generation of biodiesel is an area of importance to reduce the overall usage of fossil fuels. In the current work, biochar was produced by slow pyrolysis of Irul wood sawdust. The optimization for biochar generation was carried out for different reaction temperatures and heating durations. The biochar was used to prepare solid acid catalysts by sulfonation process. The characterization of biochar and the sulfonated catalyst were carried out using Elemental analysis, Fourier Transform Infrared spectroscopy(FTIR), Powder X-ray Diffraction(XRD), Thermo Gravimetric Analysis(TGA), Scanning Electron Microscopy(SEM) and Surface area analyzer(BET). The characterization results showed that sulfonation of biochar resulted in biochar based solid acid catalyst containing various functional acidic groups like weak acidic\\OH groups, strong acidic\\COOH and SO3 H groups. The total acid density and sulfonic acid group density of catalyst were estimated and showed excellent acidic sites concentration which gives a good catalytic activity for biodiesel production through simultaneous esterification and transesterification. The enhanced catalytic activity is due to the high acid density of SO3 H groups and the reactant accessibility towards acidic sites as well as the strong affinity between the hydrophilic reactants and the neutral OH groups which are bonded with the polycyclic aromatic carbon rings. The performance of biochar catalyst for the production of biodiesel was evaluated by comparing the yield obtained. The FTIR and Gas Chromatography–Mass Spectroscopy(GC–MS) were also carried out for the analysis of biodiesel produced.

关键词： Biochar Biochar based catalyst Pyrolysis Biomass Sulfonation

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Regression analysis of squeezing-induced hybrid nanofluid flow in Darcy-Forchheimer porous medium

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Applied Mathematics and Mechanics(English Edition) 2025年第1期46卷 193-208页

作者： k.MUHAMMAD M.SARFRAZ Department of Humanities and Sciences School of Electrical Engineering and Computer Science National University of Sciences and Technology Department of Mathematics Quaid-i-Azam University

This article presents a mathematical model addressing a scenario involving a hybrid nanofluid flow between two infinite parallel plates. One plate remains stationary, while the other moves downward at a squeezing velocity. The space between these plates contains a Darcy-Forchheimer porous medium. A mixture of water-based fluid with gold(Au) and silicon dioxide(Si O2) nanoparticles is formulated. In contrast to the conventional Fourier's heat flux equation, this study employs the Cattaneo-Christov heat flux equation. A uniform magnetic field is applied perpendicular to the flow direction, invoking magnetohydrodynamic(MHD) effects. Further, the model accounts for Joule heating, which is the heat generated when an electric current passes through the fluid. The problem is solved via NDSolve in MATHEMATICA. Numerical and statistical analyses are conducted to provide insights into the behavior of the nanomaterials between the parallel plates with respect to the flow, energy transport, and skin *** findings of this study have potential applications in enhancing cooling systems and optimizing thermal management strategies. It is observed that the squeezing motion generates additional pressure gradients within the fluid, which enhances the flow rate but reduces the frictional drag. Consequently, the fluid is pushed more vigorously between the plates, increasing the flow velocity. As the fluid experiences higher flow rates due to the increased squeezing effect, it spends less time in the region between the plates. The thermal relaxation, however, abruptly changes the temperature, leading to a decrease in the temperature fluctuations.

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Turn-on fluorescence probe for selective detection of Hg(Ⅱ)by calixpyrrole hydrazide reduced silver nanoparticle: Application to real water sample

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Chinese Chemical Letters 2016年第5期27卷 731-737页

作者： keyur D. Bhatt Disha J. Vyas Bharat A. Makwana savan M. Darjee Vinod k. Jain Hemangini Shah Department of Chemistry C.U. Shah University Wadhwan 363030 India Department of Chemistry School of Sciences Gujarat University Ahmedabad 380009 India

A simple and quick method for the synthesis of water dispersible stable silver nanoparticles has been developed. Calix[4]pyrrole octahydrazide （CPOH）, has been successfully used as a reducing as well as stabilizing agent for the synthesis of silver nanoparticles. CPOH-AgNps have been duly characterized by SPR, PSA, TEM and EDX-ray. The ability of CPOH-AgNps as selective and sensitive sensor for various ions （Pb（Ⅱ）, Cd（II）, Mn（Ⅱ）, Fe（Ⅲ）, Ni（Ⅱ）, Zn（Ⅱ）, Hg（Ⅱ）, Co（Ⅱ）, Cu（Ⅱ）） by colorimetry and spectrofluorimetry has been explored. CPOH-AgNps were found to be selective only for Hg（Ⅱ） ions. Nanomolar concentration of Hg（Ⅱ） ions can also be determined by spectrofluorimetry by increase in fluorescence intensity. Linear range of detection of Hg（Ⅱ） ions in water was found to be from 1nmol/L to mol/L. The method has been successfully applied for determination of Hg（Ⅱ） ions in ground water and industrial effluent waste water samples.

关键词： Calixpyrrole Silver nanoparticles Fluorescence study Colorimetric sensor Water samplesHg(Ⅱ) ions

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Water entry and exit of axisymmetric bodies by CFD approach

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Journal of Ocean Engineering and Science 2018年第2期3卷 156-174页

作者： Vinod V.nair S.k.Bhattacharyya Department of Ocean Engineering Indian Institute of Technology MadrasChennai 600036India

The water impact and subsequent entry of three rigid axisymmetric bodies,a sphere and two cones,in the early phase are simulated using CFD utilizing a VOF scheme to track the free surface and the results compared with the recent experimental results available in the *** penetration depth,vertical velocity and vertical acceleration time histories have been reproduced well by CFD with a wide choice of mesh density,whereas the peak pressure on impact required a much finer mesh and appropriate choice of the time *** an interaction region around the trajectory of the body with fine mesh and an adaptive time stepping strategy has worked well to capture the peak impact pressure accurately with reasonable computational ***‘full’motion of the sphere,which is buoyant,has also been simulated using CFD allowing its 6-dof motion for several cycles of entry and exit *** features of the behavior,especially the loss of symmetry of the trajectory,are discussed.

关键词： CFD Cone Sphere Water entry Water impact

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Seismic stratigraphy and the sedimentation history in the Laxmi Basin of the eastern Arabian Sea:Constraints from IODP Expedition 355

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Geoscience Frontiers 2021年第3期12卷 489-502页

作者： Nisha nair Dhananjai k.Pandey Anju Pandey R.Prerna National Centre for Polar and Ocean Research(NCPOR) Ministry of Earth SciencesVasco-da-GamaGoa 403804India H-V3-NCPOR Campus Vasco-da-GamaGoa 403804India

Detailed interpretation of seismic stratigraphic sequences in the Laxmi Basin of the eastern Arabian Sea are presented in this study using closely spaced high resolution multi-channel seismic(MCS)*** stratigraphic interpretation is further corroborated using recent drilling results in the Laxmi Basin,derived from the long sediment cores collected during International Ocean Discovery Program(IODP)Expedition *** core-log interpretation discussed in the present study,offer important insights about the lithostratigraphic variations in this *** of multi-channel seismic reflection data reveal five depositional sequences(ranging from Paleocene to Recent)that led to the development of this marginal basin since the Cenozoic *** igneous basement is successfully imaged,which was also validated by deep sea coring during the IODP Expedition *** the present study,we primarily focus on the post-rift sedimentation in the Laxmi Basin and its possible *** detailed interpretation in the prevailing tectonic framework of the basin suggests that near-shelf oldest volcaniclastic sedimentation immediately overlying the acoustic basement is linked to the onset of India-Madagascar and India-Seychelles rifting activities during the Late Cretaceous ***,during the Early-Mid to Late Miocene,the basin received maximum sedimentation dominantly through an extensive mass transport mechanism implying possible large-scale deformation on the Indian *** sediment input to the basin appears to have been fed variably via the Indus Fan as well as coastal discharge from the Indian *** total sediment thickness in the Laxmi Basin ranges from 1.1 to 3.5 *** stratigraphic information and sediment isopach maps presented here provide vital information about syn-and post-rift sedimentation pattern in the region and their long term tectonic implications.

关键词： Seismic stratigraphy Laxmi Basin Arabian Sea Site U1456 Site U1457 IODP Expedition 355

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Photolysis studies on HCOOH and HCOO^- in presence of TiO_2 photocatalyst as suspension in aqueous medium

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Journal of Natural Gas Chemistry 2009年第1期18卷 50-54页

作者： G. R. Dey k. N. R. nair k. k. Pushpa Radiation and Photochemistry Division Bhabha Atomic Research Centre Trombay Mumbai 400 085 India

Photolysis studies on formic acid （HCOOH） and formate ion （HCOO-） in presence of TiO2, a photocatalyst, as suspension in water were carried out separately using 350 nm ultraviolet light. The products, such as H2, CO, CO2 and CH4, generated during the experiments were monitored with varying the ambient, light exposure time, and the concentration of HCOOH/HCOO-. The yields of CO in all these systems increased with light exposure time. In aerated systems, CO yields were higher in contrast to the deoxygenated （Ar-purged） systems under identical conditions. It is proposed apparently that the formation of CO is taking place during the chemical reduction of in-situ generated CO2, a photo-mineralized product of HCOOH/HCOO-, but not through the direct photodecomposition or photodehydration （CO＋H2O） of solute molecules. The rates of CO formation during 1.3 M HCOOH photolysis in presence of TiO2 photocatalyst were evaluated to be 0.21 and 0.13 μl/min in aerated and Ar-purged systems, respectively. As compared with HCOOH systems, the CO yields are lower when 0.2 M HCOONa was exposed to light under identical conditions. The CO growth rates were evaluated to be 0.07 and 0.046 μl/min^-1 for aerated and deoxygenated HCOONa systems, respectively; moreover, the trend is quite similar to that of the HCOOH system. Under these conditions, the emission of H2 was also observed, and its yield was significantly higher in Ar-purged system as compared with the CO yields. However, in aerated system, the yields of these products were just opposite. The formation of low yield of methane was observed during photolysis of HCOOH/HCOO ions. In CO2 ambient, the yields of CO and H2 varied drastically with time.

关键词： formic acid formate ion photolysis TiO2

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Searching novel complex solid solution electrocatalysts in unconventional element combinations

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Nano Research 2022年第6期15卷 4780-4784页

作者： Olga A.krysiak Simon Schumacher Alan savan Wolfgang Schuhmann Alfred Ludwig Corina Andronescu Analytical Chemistry-Center for Electrochemical Sciences(CES) Faculty of Chemistry and BiochemistryRuhr University BochumUniversitätsstr.150D-44780 BochumGermany Chemical Technology Ⅲ Faculty of ChemistryCarl-Benz-Straße 199D-47057 DuisburgGermany CENIDE-Center for Nanointegration University Duisburg Essen Carl-Benz-Straße 199D-47057 DuisburgGermany Chair for Materials Discovery and Interfaces Institute for MaterialsFaculty of Mechanical EngineeringRuhr University BochumUniversitätsstr.150D-44780 BochumGermany ZGH Ruhr University BochumUniversitätsstr.150D-44780 BochumGermany

Despite outstanding accomplishments in catalyst discovery,finding new,more efficient,environmentally neutral,and noble metalfree catalysts remains challenging and ***,complex solid solutions consisting of at least five different elements and often named as high-entropy alloys have emerged as a new class of electrocatalysts for a variety of *** multicomponent combinations of elements facilitate tuning of active sites and catalytic *** optimal catalyst composition remains difficult,making testing of a very high number of them *** present the high-throughput screening of the electrochemical activity of thin film material libraries prepared by combinatorial co-sputtering of metals which are commonly used in catalysis(Pd,Cu,Ni)combined with metals which are not commonly used in catalysis(Ti,Hf,Zr).Introducing unusual elements in the search space allows discovery of catalytic activity for hitherto unknown *** libraries with very similar composition spreads can show different activities *** trends for different *** order to address the inherent challenge of the huge combinatorial material space and the inability to predict active electrocatalyst compositions,we developed a high-throughput process based on co-sputtered material libraries,and performed high-throughput characterization using energy dispersive X-ray spectroscopy(EDS),scanning transmission electron microscopy(SEM),X-ray diffraction(XRD)and conductivity measurements followed by electrochemical screening by means of a scanning droplet *** results show surprising material compositions with increased activity for the oxygen reduction reaction and the hydrogen evolution *** data are important input data for future data-driven materials prediction.

关键词： high-entropy alloys electrocatalysis high-throughput screening thin films hydrogen evolution reaction oxygen reduction reaction

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Basement tectonics and flexural subsidence along western continental margin of India

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Geoscience Frontiers 2017年第5期8卷 1009-1024页

作者： D.k.Pandey Nisha nair Anju Pandey G. Sriram ESSO-National Centre for Antarctic and Ocean Research Goa India

The Paleocene-recent post-rift subsidence history recorded in the Mumbai Offshore Basin off western continental margin of India is examined. Results obtained through 2-D flexural backstripping modelling of new seismic data reveal considerable thermo-tectonic subsidence over last ca. 56 Myr. Reverse postrift subsidence modelling with variable β stretching factor predicts residual topography of ca. 2000 m to the west of Shelf Margin Basin and fails to restore late Paleocene horizon and the underlying igneous basement to the sea level. This potentially implies that:(1) either the igneous basement formed during the late Cretaceous was emplaced under open marine environs; or(2) a laterally varying cumulative subsidence occurred within Mumbai Offshore Basin(MOB) during ca. 68 to ca. 56 Ma. Pre-depositional topographic variations at ca. 56 Ma across the basin could be attributed to the extensional processes such as varied lower crustal underplating along Western Continental Margin of India(WCMI). Investigations about basement tectonics after unroofing of sediments since late Paleocene from this region support a transitional and heavily stretched nature of crust with high to very high β factors. Computations of past sediment accumulation rates show that the basin sedimentation peaked during late Miocene concurrently with uplift of Himalayan-Tibetan Plateau and intensification of Indian monsoon system. Results from basin subsidence modelling presented here may have significant implications for further studies attempting to explore tectono-climatic interactions in Asia.

关键词： Continental rifting Subsidence Mumbai Offshore Basin Backstripping Arabian Sea Laxmi Basin

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