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Nitration of Jharia basin coals,India:a study of structural modifications by XRD and FTIR techniques

International Journal of Coal Science & Technology 2021年第5期8卷 1034-1053页

作者： Prabal Boral atul k.varma Sudip Maity CSIR-Central Institute of Mining and Fuel Research PO:FRIDhanbad 828108India Department of Applied Geology Indian Institute of Technology(ISM)Dhanbad826004India

Four coal samples from Jharia basin,India are treated with nitric acid in glacial acetic acid and aqueous media to find out the chemical,petrographic and spatial structure of the organic mass by X-ray diffraction(XRD)and Fourier Transform Infrared Spectroscopy(FTIR)techniques.X-ray parameters of coal like interlayer spacing(d_(002)),crystallite size(L_(c)),aroamticity(f_(a)),average number of aromatic layers(N_(c)),and coal rank(I_(26)/I_(20))have been determined using profilefitting software.Considerable variation is observed in treated coals in comparison to the demineralized coals.The d_(002)values of treated coals have increased in both the media showing increase in disordering of organic moieties.A linear relationship has been observed between d_(002)values with the volatile matter of the coals.Similarly,the d_(002)values show linear relationship with C_(dmf) contents for demineralized as well as for the treated coals in both the media.The L_(c) and N_(c) values have decreased in treated coals corresponding to demineralized coals.The present study shows that nitration in both the media is capable of removing the aliphatic side chains from the coals and aromaticity(f_(a))increases with increase in rank and shows a linear relationship with the vitrinite reflectance.The corresponding I_(26)/I_(20)values are least for treated coals in glacial acetic acid medium followed by raw and then to treated coals in aqueous medium.FTIR studies show that coal arenes of the raw coals are converted into nitro-arenes in structurally modified coals(SMCs)in both the media,the corresponding bands at 1550-1490 and 1355-1315 cm^(-1) respectively.FTIR study confirms that nitration is the predominant phenomenon,though,oxidation and nitration phenomena takes place simultaneously during treatment with nitric acid to form SMCs.In comparison to raw coals,the SMCs show higher aromaticity and may be easily converted to coal derived products like activated carbon and specialty carbon materials.

关键词： Coal Micro-structure Nitration XRD FTIR

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Influence of coke structure on coke quality using image analysis method

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International Journal of Coal Science & Technology 2018年第4期5卷 473-485页

作者： B.Ghosh B.k.Sahoo B.Chakrabortv k.k.Manjhi S.k.Das J.N.Sahu atul k.varma Research & Development Centre for Iron and Steel Steel Authority of India Limited (SAIL)RanchiJharkhand 834002India Institute of Chenlical Technology Faculty of ChemistryUniversity of Stuttgart70550 StuttgartGermany Coal Geology and Organic Petrology Laboratory Department of Applied GeologyIITIndian School of Mines (ISM)Dhanbad 826004India South Ural State University 76Lenin Aven.ChelyabinskRussia 454080

The quality of coke affects the performance of the blast furnace, factors affecting coke quality include coal properties, coal charge granulometry and carbonization conditions. The coke properties in elude the size analysis, cold strength (Micum Indices-M4(). MI0) and hot strength (Coke Reactivity Index-CRI, Coke Strength after Reaction-CSR) properties and structural properties such as coke structure and texture. Structural properties comprise the porosity, pore-cell wall thickness and pore sizes, while textures consist of the carbon forms in the coke. In present work, advanced method such as image analysis method was used to interpret coke microstructure. Conventional methods such as determination of coke porosity by measurement of real and apparent density and mercury porosimetry have a number of limitations. Coke size, magnification, number of image frames captured, process of pellet preparations and coke properties such as M4(), M|0, CRI and CSR (low, medium and high values) were taken as variables for experimental purposes. The coke structure parameters such as porosity, length, perimeter, breadth, roundness, pore-wall thickness and pore size distribution of the pores were determined by image analysis method. This method provided average porosity in addition to pore-wall thickness and pore-size distribution. The pore wall thickness measuremenl by image analysis method provided significant correlations with M40, CRI and CSR values. This explained the usability of image analysis for coke structure measurement.

关键词： Image analysis Coke structure Porosity Micro structure Roundness Pore wall thickness

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MXenes for Bioinspired Soft Actuators:Advancements in Angle-Independent Structural Colors and Beyond

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Nano-Micro Letters 2024年第8期16卷 18-34页

作者： Siavash Iravani Rajender S.varma Independent Researcher W Nazar STBoostan AveIsfahanIran Centre of Excellence for Research in Sustainable Chemistry Department of ChemistryFederal University of São CarlosSão CarlosSP 13565‑905Brazil

Soft actuators have garnered substantial attention in current years in view of their potential appliances in diverse domains like robotics,biomedical devices,and biomimetic systems.These actuators mimic the natural movements of living organisms,aiming to attain enhanced flexibility,adaptability,and versatility.On the other hand,angle-independent structural color has been achieved through innovative design strategies and engineering approaches.By carefully controlling the size,shape,and arrangement of nanostructures,researchers have been able to create materials exhibiting consistent colors regardless of the viewing angle.One promising class of materials that holds great potential for bioinspired soft actuators is MXenes in view of their exceptional mechanical,electrical,and optical properties.The integration of MXenes for bioinspired soft actuators with angle-independent structural color offers exciting possibilities.Overcoming material compatibility issues,improving color reproducibility,scalability,durability,power supply efficiency,and cost-effectiveness will play vital roles in advancing these technologies.This perspective appraises the development of bioinspired MXene-centered soft actuators with angleindependent structural color in soft robotics.

关键词： MXenes MXene-based composites Bioinspired soft robotics Angle-independent structural color

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Nano/Micro-Structural Supramolecular Biopolymers: Innovative Networks with the Boundless Potential in Sustainable Agriculture

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Nano-Micro Letters 2024年第8期16卷 79-101页

作者： Roohallah Saberi Riseh Mohadeseh Hassanisaadi Masoumeh Vatankhah Rajender S.varma Vijay kumar Thakur Department of Plant Protection Faculty of AgricultureVali-e-Asr University of RafsanjanImam Khomeini SquareRafsanjan ***Iran Centre of Excellence for Research in Sustainable Chemistry Department of ChemistryFederal University of São CarlosSão CarlosSP 13565‑905Brazil Biorefining and Advanced Materials Research Center Scotland’s Rural Collage(SRUC)Edinburgh EH93JGUK

Sustainable agriculture plays a crucial role in meeting the growing global demand for food while minimizing adverse environmental impacts from the overuse of synthetic pesticides and conventional fertilizers.In this context,renewable biopolymers being more sustainable offer a viable solution to improve agricultural sustainability and production.Nano/micro-structural supramolecular biopolymers are among these innovative biopolymers that are much sought after for their unique features.These biomaterials have complex hierarchical structures,great stability,adjustable mechanical strength,stimuli-responsiveness,and self-healing attributes.Functional molecules may be added to their flexible structure,for enabling novel agricultural uses.This overview scrutinizes how nano/micro-structural supramolecular biopolymers may radically alter farming practices and solve lingering problems in agricultural sector namely improve agricultural production,soil health,and resource efficiency.Controlled bioactive ingredient released from biopolymers allows the tailored administration of agrochemicals,bioactive agents,and biostimulators as they enhance nutrient absorption,moisture retention,and root growth.Nano/micro-structural supramolecular biopolymers may protect crops by appending antimicrobials and biosensing entities while their eco-friendliness supports sustainable agriculture.Despite their potential,further studies are warranted to understand and optimize their usage in agricultural domain.This effort seeks to bridge the knowledge gap by investigating their applications,challenges,and future prospects in the agricultural sector.Through experimental investigations and theoretical modeling,this overview aims to provide valuable insights into the practical implementation and optimization of supramolecular biopolymers in sustainable agriculture,ultimately contributing to the development of innovative and eco-friendly solutions to enhance agricultural productivity while minimizing environmental impact.

关键词： Supramolecular Biopolymers Sustainable agriculture Nanotechnology

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Geochemical signatures of potassium metasomatism in anthracite from the Himalayan fold‑thrust belts of Sikkim,India

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International Journal of Coal Science & Technology 2022年第2期9卷 48-69页

作者： Santanu Ghosh Anwita Ojha atul kumar varma Coal Geology and Organic Petrology Laboratory Department of Applied GeologyIndian Institute of Technology(Indian School of Mines)DhanbadJharkhand 826004India Department of Earth Sciences Indian Institute of Technology BombayPowaiMumbaiMaharashtra 400076India

The present study focuses on the inorganic geochemical features of the bituminous coal samples from the Raniganj and the Jharia Basins,as well as the anthracite samples from the Himalayan fold-thrust belts of Sikkim,India.The SiO_(2)content(48.05 wt%to 65.09 wt%and 35.92 wt%to 50.11 wt%in the bituminous and anthracite samples,respectively)and the ratio of Al_(2)O_(3)/TiO_(2)(6.97 to 17.03 in the bituminous coal samples and 10.34 to 20.07 in the anthracite samples)reveal the intermediate igneous source rock composition of the minerals.The ratio of the k_(2)O/Al_(2)O_(3)in the ash yield of the bituminous coal samples(0.03 to 0.09)may suggest the presence of kaolinite mixed with montmorillonite,while its range in the ash yield of the anthracite samples(0.16 to 0.27)may imply the presence of illite mixed with kaolinite.The chemical index of alteration values may suggest the moderate to strong chemical weathering of the source rock under sub-humid to humid climatic conditions.The plot of the bituminous coal samples in the A–CN–k diagram depicts the traditional weathering trend of parent rocks,but the anthracite samples plot near the illite feld and are a bit ofset from the weathering trend.This may imply the plausible infuences of the potassium-metasomatism at post coalifcation stages,which is further supported by high k_(2)O/Na_(2)O ratio(29.88–80.13).The Fourier transform infrared spectra further reveal the hydroxyl stretching intensity of illite in the anthracite samples substantiating the efect of the epigenetic potassium-metasomatism.The decrease in total kaolinite intensity/compound intensity of quartz and feldspar may provide additional evidence towards this epigenetic event.

关键词： Himalayan fold-thrust belts Anthracite Potassium metasomatism kaolinite to quartz-feldspar intensity ratio Montmorillonite stretching and bending intensities Illite-stretching frequency

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Spectral narratives of microstructural restyling and their controls on hydrocarbon generation potential from coal

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International Journal of Coal Science & Technology 2023年第3期10卷 167-189页

作者： Tushar Adsul Santanu Ghosh Anwita Ojha Sudip Bhattacharyya atul kumar varma Coal Geology and Organic Petrology Laboratory Department of Applied GeologyIndian Institute of Technology(Indian School of Mines)DhanbadJharkhand 826004India Department of Geology Mizoram UniversityAizawlMizoram 796004India Specialized Coal Petrography Laboratory Natural Energy ResourcesMission II-BGeological Survey of IndiaDK-6Sector-IlSalt Lake CityKolkataWest Bengal 700091India

The low to medium-rank Tertiary coals from Meghalaya,India,are explored for the first time for their comprehensive micro-structural characterization using the FTIR and Raman spectroscopy.Further,results from these coals are compared with the Permian medium and high-rank coals to understand the microstructural restyling during coalification and its controls on hydrocarbon generation.The coal samples are grouped based on the mean random vitrinite reflectance values to record the transformations in spectral attributes with increasing coal rank.The aliphatic carbon and the apparent aromaticity respond sharply to the first coalification jump(R:0.50%)during low to medium-rank transition and anchizonal metamorphism of the high-rank coals.Moreover,the Raman band intensity ratio changes during the first coalification jump but remains invari-able in the medium-rank coals and turns subtle again during the onset of pregraphitization in high-rank coals,revealing a polynomial trend with the coal metamorphism.The Rock-Eval hydrogen index and genetic potential also decline sharply at the first coalification jump.Besides,an attempt to comprehend the coal microstructural controls on the hydrocarbon poten-tial reveals that the Tertiary coals comprise highly reactive aliphatic functionalities in the type I-S kerogen,along with the low paleotemperature(74.59-112.28℃)may signify their potential to generate early-mature hydrocarbons.However,the presence of type II-II admixed kerogen,a lesser abundance of reactive moieties,and overall moderate paleotemperature(91.93-142.52℃)of the Permian medium-rank coals may imply their mixed hydrocarbon potential.Meanwhile,anchizonal metamorphism,polycondensed aromatic microstructure,and high values of paleotemperature(~334.25 to~366.79℃)of the high-rank coals indicate a negligible potential of producing any hydrocarbons.

关键词： Early mature oil generation Meghalaya high-sulfur coal Type II-S kerogen Microstructural ordering Coalification jump Hydrocarbon generation potential

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MXene-Based Composites as Nanozymes in Biomedicine: A Perspective

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Nano-Micro Letters 2022年第12期14卷 447-463页

作者： Siavash Iravani Rajender S.varma Faculty of Pharmacy and Pharmaceutical Sciences Isfahan University of Medical SciencesIsfahanIran Regional Centre of Advanced Technologies and Materials Department of Physical ChemistryFaculty of SciencePalacky University in OlomoucSlechtitelu2778371 OlomoucCzech Republic

MXene-based nanozymes have garnered considerable attention because of their potential environmental and biomedical applications.These materials encompass alluring and manageable catalytic performances and physicochemical features,which make them suitable as(bio)sensors with high selectivity/sensitivity and efficiency.MXene-based structures with suitable electrical conductivity,biocompatibility,large surface area,optical/magnetic properties,and thermal/mechanical features can be applied in designing innovative nanozymes with area-dependent electrocatalytic performances.Despite the advances made,there is still a long way to deploy MXene-based nanozymes,especially in medical and healthcare applications;limitations pertaining the peroxidaselike activity and sensitivity/selectivity may restrict further practical applications of pristine MXenes.Thus,developing an efficient surface engineering tactic is still required to fabricate multifunctional MXene-based nanozymes with excellent activity.To obtain MXene-based nanozymes with unique physicochemical features and high stability,some crucial steps such as hybridization and modification ought to be performed.Notably,(nano)toxicological and long-term biosafety analyses along with clinical translation studies still need to be comprehensively addressed.Although very limited reports exist pertaining to the biomedical potentials of MXene-based nanozymes,the future explorations should transition toward the extensive research and detailed analyses to realize additional potentials of these structures in biomedicine with a focus on clinical and industrial aspects.In this perspective,therapeutic,diagnostic,and theranostic applications of MXene-based nanozymes are deliberated with a focus on future per-spectives toward more successful clinical translational studies.The current state-of-the-art biomedical advances in the use of MXene-based nanozymes,as well as their developmental challenges and future prospects are also highlighted.In view of the fascinating properties of MXene-based

关键词： MXenes MXene-based nanozymes Therapeutics Diagnostics Theranostics

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Wetting of MXenes and Beyond

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Nano-Micro Letters 2023年第8期15卷 141-153页

作者： Massoud Malaki Rajender S.varma Department of Mechanical Engineering Isfahan University of TechnologyDaneshgah e Sanati HwyKhomeyni ShahrIsfahan 84156‑83111Iran Regional Centre of Advanced Technologies and Materials Palacky University in OlomoucŠlechtitelů2778371 OlomoucCzech Republic

MXenes are a class of 2D nanomaterials with exceptional tailormade properties such as mechano-ceramic nature,rich chemistry,and hydrophilicity,to name a few.However,one of the most challenging issues in any composite/hybrid system is the interfacial wetting.Having a superior integrity of a given composite system is a direct consequence of the proper wettability.While wetting is a fundamental feature,dictating many physical and chemical attributes,most of the common nanomaterials possesses poor affinity due to hydrophobic nature,making them hard to be easily dispersed in a given composite.Thanks to low contact angle,MXenes can offer themselves as an ideal candidate for manufacturing different nano-hybrid structures.Herein this review,it is aimed to particularly study the wettability of MXenes.In terms of the layout of the present study,MXenes are first briefly introduced,and then,the wettability phenomenon is discussed in detail.Upon reviewing the sporadic research efforts conducted to date,a particular attention is paid on the current challenges and research pitfalls to light up the future perspectives.It is strongly believed that taking the advantage of MXene’s rich hydrophilic surface may have a revolutionizing role in the fabrication of advanced materials with exceptional features.

关键词： MXene Wetting Hydrophilicity Composites 2D material

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Swarm Optimization and Machine Learning for Android Malware Detection

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Computers, Materials & Continua 2022年第12期73卷 6327-6345页

作者： k.Santosh Jhansi P.Ravi kiran varma Sujata Chakravarty Centurion University of Technology and Management ParalakhemundiOdishaIndia Maharaj Vijayaram Gajapathi Raj College of Engineering VizianagaramIndia Centurion University of Technology and Management BhubaneswarOdishaIndia

Malware Security Intelligence constitutes the analysis of applications and their associated metadata for possible security threats.Application Programming Interfaces(API)calls contain valuable information that can help with malware identification.The malware analysis with reduced feature space helps for the efficient identification of malware.The goal of this research is to find the most informative features of API calls to improve the android malware detection accuracy.Three swarm optimization methods,viz.,Ant Lion Optimization(ALO),Cuckoo Search Optimization(CSO),and Firefly Optimization(FO)are applied to API calls using auto-encoders for identification of most influential features.The nature-inspired wrapperbased algorithms are evaluated using well-known Machine Learning(ML)classifiers such as Linear Regression(LR),Decision Tree(DT),Random Forest(RF),k-Nearest Neighbor(kNN)&SupportVector Machine(SVM).A hybrid Artificial Neuronal Classifier(ANC)is proposed for improving the classification of android malware.The experimental results yielded an accuracy of 98.87%with just seven features out of hundred API call features,i.e.,a massive 93%of data optimization.

关键词： Android malware API calls auto-encoders ant lion optimization cuckoo search optimization firefly optimization artificial neural networks artificial neuronal classifier

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Can propensity score matching replace randomized controlled trials?

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World Journal of Methodology 2024年第1期14卷 58-70页

作者： Matthias Yi Quan Liau En Qi Toh Shamir Muhamed Surya varma Selvakumar Vishalkumar Girishchandra Shelat Lee kong Chian School of Medicine Nanyang Technological UniversitySingapore 308232Singapore Department of General Surgery Tan Tock Seng HospitalSingapore 308433Singapore Surgical Science Training Centre Tan Tock Seng HospitalSingapore 308433Singapore

Randomized controlled trials(RCTs)have long been recognized as the gold standard for establishing causal relationships in clinical research.Despite that,various limitations of RCTs prevent its widespread implementation,ranging from the ethicality of withholding potentially-lifesaving treatment from a group to relatively poor external validity due to stringent inclusion criteria,amongst others.However,with the introduction of propensity score matching(PSM)as a retrospective statistical tool,new frontiers in establishing causation in clinical research were opened up.PSM predicts treatment effects using observational data from existing sources such as registries or electronic health records,to create a matched sample of participants who received or did not receive the intervention based on their propensity scores,which takes into account characteristics such as age,gender and comorbidities.Given its retrospective nature and its use of observational data from existing sources,PSM circumvents the aforementioned ethical issues faced by RCTs.Majority of RCTs exclude elderly,pregnant women and young children;thus,evidence of therapy efficacy is rarely proven by robust clinical research for this population.On the other hand,by matching study patient characteristics to that of the population of interest,including the elderly,pregnant women and young children,PSM allows for generalization of results to the wider population and hence greatly increases the external validity.Instead of replacing RCTs with PSM,the synergistic integration of PSM into RCTs stands to provide better research outcomes with both methods complementing each other.For example,in an RCT investigating the impact of mannitol on outcomes among participants of the Intensive Blood Pressure Reduction in Acute Cerebral Hemorrhage Trial,the baseline characteristics of comorbidities and current medications between treatment and control arms were significantly different despite the randomization protocol.Therefore,PSM was incorporated in its analysis to create sam

关键词： Propensity score matching Randomized controlled trials Randomization Clinical practice Validity Ethics

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