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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 *** materials encompass alluring and manageable catalytic performances and physicochemical features,which make them suitable as(bio)sensors with high selectivity/sensitivity and ***-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 *** 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 ***,developing an efficient surface engineering tactic is still required to fabricate multifunctional MXene-based nanozymes with excellent *** obtain MXene-based nanozymes with unique physicochemical features and high stability,some crucial steps such as hybridization and modification ought to be ***,(nano)toxicological and long-term biosafety analyses along with clinical translation studies still need to be comprehensively *** 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 *** 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 *** 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 *** v

关键词： MXenes MXene-based nanozymes Therapeutics Diagnostics Theranostics

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 ***,one of the most challenging issues in any composite/hybrid system is the interfacial *** a superior integrity of a given composite system is a direct consequence of the proper *** 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 *** to low contact angle,MXenes can offer themselves as an ideal candidate for manufacturing different nano-hybrid *** this review,it is aimed to particularly study the wettability of *** terms of the layout of the present study,MXenes are first briefly introduced,and then,the wettability phenomenon is discussed in *** 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 *** 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

Plant Pollen Grains:A Move Towards Green Drug and Vaccine Delivery Systems

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Nano-Micro Letters 2021年第8期13卷 218-230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 Czech Advanced Technology and Research InstitutePalackýUniversity in OlomoucŠlechtitelů2778371 OlomoucCzech Republic

Pollen grains and plant spores have emerged as innovative biomaterials for various applications such as drug/vaccine delivery,catalyst support,and the removal of heavy *** natural microcapsules comprising spore shells and pollen grain are designed for protecting the genetic materials of plants from exterior *** layers make up the shell,the outer layer(exine)that comprised largely of sporopollenin,and the inner layer(intine)that built chiefly of *** microcapsule shells,namely hollow sporopollenin exine capsules have some salient features such as homogeneity in size,non-toxic nature,resilience to both alkalis and acids,and the potential to withstand at elevated temperatures;they have displayed promising potential for the microencapsulation and the controlled drug delivery/*** important attribute of mucoadhesion to intestinal tissues can prolong the interaction of sporopollenin with the intestinal mucosa directing to an augmented effectiveness of nutraceutical or drug ***,current trends and prospects related to the application of plant pollen grains for the delivery of vaccines and drugs and vaccine are discussed.

关键词： Pollens Sporopollenin Drug delivery Vaccine delivery Plant pollen grains Microcapsule shells

Recent advances in catalytic combustion of AP-based composite solid propellants

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Defence Technology（防务技术） 2021年第3期17卷 1013-1031页

作者： Narendra Yadav Prem Kumar Srivastava Mohan varma Department of Space Engineering&Rocketry India Department of Chemistry Birla Institute of TechnologyMesraRanchiIndia

Composite solid propellants(CSPs) have widely been used as main energy source for propelling the rockets in both space and military applications. Internal ballistic parameters of rockets like characteristic exhaust velocity, specific impulse, thrust, burning rate etc., are measured to assess and control the performance of rocket motors. The burn rate of solid propellants has been considered as most vital parameter for design of solid rocket motors to meet specific mission requirements. The burning rate of solid propellants can be tailored by using different constituents, extent of oxidizer loading and its particle size and more commonly by incorporating suitable combustion catalysts. Various metal oxides(MOs),complexes, metal powders and metal alloys have shown positive catalytic behaviour during the combustion of CSPs. These are usually solid-state catalysts that play multiple roles in combustion of CSPs such as reduction in activation energy, enhancement of rate of reaction, modification of sequences in reaction-phase, influence on condensed-phase combustion and participation in combustion process in gas-phase reactions. The application of nanoscale catalysts in CSPs has increased considerably in recent past due to their superior catalytic properties as compared to their bulk-sized counterparts. A large surface-to-volume ratio and quantum size effect of nanocatalysts are considered to be plausible reasons for improving the combustion characteristics of propellants. Several efforts have been made to produce nanoscale combustion catalysts for advanced propellant formulations to improve their energetics. The work done so far is largely scattered. In this review, an effort has been made to introduce various combustion catalysts having at least a metallic entity. Recent developments of nanoscale combustion catalysts with their specific merits are discussed. The combustion chemistry of a typical CSP is briefly discussed for providing a better understanding on role of co

关键词： Composite solid propellants Burn rate modifier Metallic nano-catalysts Catalytic combustion Thermal decomposition

Water and nutrient recovery from urine:A lead up trail using nano-structured In_(2)S_(3)photo electrodes

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Chinese Physics B 2021年第5期30卷 531-535页

作者： R Jayakrishnan T R Sreerev Adith varma Department of Physics University of KeralaThiruvananthapuramKerala 695581India Photovoltaic Research Laboratory Christian College Chenagnnur 689122India

Developments of economic systems are critical for bio-regenerative life support systems in manned space *** this work we report on the feasibility of using two direct sunlight powered processes sequentially for the recovery of water and nutrients from *** work presents experimental evidence on nutrient and water recovery achieved using the proto-type designed and *** report the design and testing of a solar still which would serve on the nutrient recovery *** cooled condensate from the solar still is fed into a solar powered electrolysis unit where nano-structured indium sulphide(In_(2)S_(3))thin films coated over fluorine doped tin oxide(SnO_(2):F)substrate serve as one of the working *** electrolysis takes place in the absence of an electrolyte which manifests as a technical achievement of our *** results show that the COD level in the recycled water is very *** In_(2)S_(3)photo-electrodes are stable without any physical damage after the process.

关键词： semiconductors water quality thin film structure and morphology electrolysis

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,*** 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 *** 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 *** chemical index of alteration values may suggest the moderate to strong chemical weathering of the source rock under sub-humid to humid climatic *** 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 *** 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 *** 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

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

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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 *** variation is observed in treated coals in comparison to the demineralized *** 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 ***,the d_(002)values show linear relationship with C_(dmf) contents for demineralized as well as for the treated coals in both the *** L_(c) and N_(c) values have decreased in treated coals corresponding to demineralized *** 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 *** 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 *** 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) *** study confirms that nitration is the predominant phenomenon,though,oxidation and nitration phenomena takes place simultaneously during treatment with nitric acid to form *** 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

Microstructures in a Nb-Cr-V-W-Ta high entropy alloy during annealing

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Journal of Materials Science & Technology 2020年第18期52卷 66-72页

作者： S.K.varma Francelia Sanchez C.V.Ramana Department of Metallurgical Materials and Biomaterials EngineeringThe University of Texas at El PasoEl PasoTX 79968-0520USA Mechanical Engineering Department The University of Texas at El PasoEl PasoTX 79968-0520USA

A Nb-Cr-V-W-Ta high entropy alloy has been subjected to annealing treatment at 600,700 and 800℃in air for 6 *** different phases have been identified based on their composition in the as received *** annealing treatment does not alter the phase analysis and compositions except for the W-rich phase where minor changes in the composition have been *** is considered as an experimental evidence of sluggish diffusivity associated with *** of phase transformation during the heating and the minimal changes in observed compositions of the phases is an indication of the resistance to diffusion offered by the elements of the high entropy *** electron microscopy(SEM),energy dispersive spectroscopy(EDS)and color X-ray elemental mapping have been used to conduct this research.

关键词： HEA Microstructures in a Nb-Cr-V-W-Ta high entropy alloy during annealing

Numerical modeling of a tunnel in jointed rocks subjected to seismic loading

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Underground Space 2019年第2期4卷 133-146页

作者： Malavika varma V.B.Maji A.Boominathan Department of Civil Engineering Indian Institute of Technology MadrasChennaiIndia

The studies on the performance of tunnels under static loads are reported extensively in the literature but their performances under dynamic loads are *** present study highlights some of the important aspects of jointed rock tunnels during seismic *** literature review provides a shake table experimental study of a jointed rock tunnel.A Universal Distinct Element Code(UDEC)model is developed from this shake table *** model tunnel is subjected to a scaled input motion of the 1985 Mexico *** numerical results are validated systematically with the findings of the shake table ***,the developed numerical model is used to perform parametric studies to understand the effect of in-situ stress,joint angles,joint stiffness,and joint friction angle on the deformation and stability of the tunnel under the same earthquake input *** is observed that some joint angle combinations form a wedge that yields excessive deformation and subsequently a complete *** exponential decrease in deformation occurred in the tunnel as the joint stiffness *** is found that the shallow tunnels are more susceptible to damage under the action of earthquake loads.

关键词： Tunnel Jointed rocks Seismic loading UDEC