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Now showing items 1 - 16 of 65

  • Production and processing of graphene and related materials

    Backes, Claudia   Abdelkader, Amr M.   Alonso, Concepcion   Andrieux-Ledier, Amandine   Arenal, Raul   Azpeitia, Jon   Balakrishnan, Nilanthy   Banszerus, Luca   Barjon, Julien   Bartali, Ruben   Bellani, Sebastiano   Berger, Claire   Berger, Reinhard   Ortega, M. M. Bernal   Bernard, Carlo   Beton, Peter H.   Beyer, Andre   Bianco, Alberto   Boggild, Peter   Bonaccorso, Francesco   Barin, Gabriela Borin   Botas, Cristina   Bueno, Rebeca A.   Carriazo, Daniel   Castellanos-Gomez, Andres   Christian, Meganne   Ciesielski, Artur   Ciuk, Tymoteusz   Cole, Matthew T.   Coleman, Jonathan   Coletti, Camilla   Crema, Luigi   Cun, Huanyao   Dasler, Daniela   De Fazio, Domenico   Diez, Noel   Drieschner, Simon   Duesberg, Georg S.   Fasel, Roman   Feng, Xinliang   Fina, Alberto   Forti, Stiven   Galiotis, Costas   Garberoglio, Giovanni   Garcia, Jorge M.   Antonio Garrido, Jose   Gibertini, Marco   Goelzhaeuser, Armin   Gomez, Julio   Greber, Thomas   Hauke, Frank   Hemmi, Adrian   Hernandez-Rodriguez, Irene   Hirsch, Andreas   Hodge, Stephen A.   Huttel, Yves   Jepsen, Peter U.   Jimenez, Ignacio   Kaiser, Ute   Kaplas, Tommi   Kim, HoKwon   Kis, Andras   Papagelis, Konstantinos   Kostarelos, Kostas   Krajewska, Aleksandra   Lee, Kangho   Li, Changfeng   Lipsanen, Harri   Liscio, Andrea   Lohe, Martin R.   Loiseau, Annick   Lombardi, Lucia   Francisca Lopez, Maria   Martin, Oliver   Martin, Cristina   Martinez, Lidia   Angel Martin-Gago, Jose   Ignacio Martinez, Jose   Marzari, Nicola   Mayoral, Alvaro   McManus, John   Melucci, Manuela   Mendez, Javier   Merino, Cesar   Merino, Pablo   Meyer, Andreas P.   Miniussi, Elisa   Miseikis, Vaidotas   Mishra, Neeraj   Morandi, Vittorio   Munuera, Carmen   Munoz, Roberto   Nolan, Hugo   Ortolani, Luca   Ott, Anna K.   Palacio, Irene   Palermo, Vincenzo   Parthenios, John   Pasternak, Iwona   Patane, Amalia   Prato, Maurizio   Prevost, Henri   Prudkovskiy, Vladimir   Pugno, Nicola   Rojo, Teofilo   Rossi, Antonio   Ruffieux, Pascal   Samori, Paolo   Schue, Leonard   Setijadi, Eki   Seyller, Thomas   Speranza, Giorgio   Stampfer, Christoph   Stenger, Ingrid   Strupinski, Wlodek   Svirko, Yuri   Taioli, Simone   Teo, Kenneth B. K.   Testi, Matteo   Tomarchio, Flavia   Tortello, Mauro   Treossi, Emanuele   Turchanin, Andrey   Vazquez, Ester   Villaro, Elvira   Whelan, Patrick R.   Xia, Zhenyuan   Yakimova, Rositza   Yang, Sheng   Reza Yazdi, G.   Yim, Chanyoung   Yoon, Duhee   Zhang, Xianghui   Zhuang, Xiaodong   Colombo, Luigi   Ferrari, Andrea C.   Garcia-Hernandez, Mar  

    We present an overview of the main techniques for production and processing of graphene and related materials (GRMs), as well as the key characterization procedures. We adopt a 'hands-on' approach, providing practical details and procedures as derived from literature as well as from the authors' experience, in order to enable the reader to reproduce the results. Section I is devoted to 'bottom up' approaches, whereby individual constituents are pieced together into more complex structures. We consider graphene nanoribbons (GNRs) produced either by solution processing or by on-surface synthesis in ultra high vacuum (UHV), as well carbon nanomembranes (CNM). Production of a variety of GNRs with tailored band gaps and edge shapes is now possible. CNMs can be tuned in terms of porosity, crystallinity and electronic behaviour. Section II covers 'top down' techniques. These rely on breaking down of a layered precursor, in the graphene case usually natural crystals like graphite or artificially synthesized materials, such as highly oriented pyrolythic graphite, monolayers or few layers (FL) flakes. The main focus of this section is on various exfoliation techniques in a liquid media, either intercalation or liquid phase exfoliation (LPE). The choice of precursor, exfoliation method, medium as well as the control of parameters such as time or temperature are crucial. A definite choice of parameters and conditions yields a particular material with specific properties that makes it more suitable for a targeted application. We cover protocols for the graphitic precursors to graphene oxide (GO). This is an important material for a range of applications in biomedicine, energy storage, nanocomposites, etc. Hummers' and modified Hummers' methods are used to make GO that subsequently can be reduced to obtain reduced graphene oxide (RGO) with a variety of strategies. GO flakes are also employed to prepare three-dimensional (3d) low density structures, such as sponges, foams, hydro- or aerogels. The assembly of flakes into 3d structures can provide improved mechanical properties. Aerogels with a highly open structure, with interconnected hierarchical pores, can enhance the accessibility to the whole surface area, as relevant for a number of applications, such as energy storage. The main recipes to yield graphite intercalation compounds (GICs) are also discussed. GICs are suitable precursors for covalent functionalization of graphene, but can also be used for the synthesis of uncharged graphene in solution. Degradation of the molecules intercalated in GICs can be triggered by high temperature treatment or microwave irradiation, creating a gas pressure surge in graphite and exfoliation. Electrochemical exfoliation by applying a voltage in an electrolyte to a graphite electrode can be tuned by varying precursors, electrolytes and potential. Graphite electrodes can be either negatively or positively intercalated to obtain GICs that are subsequently exfoliated. We also discuss the materials that can be amenable to exfoliation, by employing a theoretical data-mining approach. The exfoliation of LMs usually results in a heterogeneous dispersion of flakes with different lateral size and thickness. This is a critical bottleneck for applications, and hinders the full exploitation of GRMs produced by solution processing. The establishment of procedures to control the morphological properties of exfoliated GRMs, which also need to be industrially scalable, is one of the key needs. Section III deals with the processing of flakes. (Ultra)centrifugation techniques have thus far been the most investigated to sort GRMs following ultrasonication, shear mixing, ball milling, microfluidization, and wet-jet milling. It allows sorting by size and thickness. Inks formulated from GRM dispersions can be printed using a number of processes, from inkjet to screen printing. Each technique has specific rheological requirements, as well as geometrical constraints. The solvent choice is critical, not only for the GRM stability, but also in terms of optimizing printing on different substrates, such as glass, Si, plastic, paper, etc, all with different surface energies. Chemical modifications of such substrates is also a key step. Sections IV-VII are devoted to the growth of GRMs on various substrates and their processing after growth to place them on the surface of choice for specific applications. The substrate for graphene growth is a key determinant of the nature and quality of the resultant film. The lattice mismatch between graphene and substrate influences the resulting crystallinity. Growth on insulators, such as SiO2, typically results in films with small crystallites, whereas growth on the close-packed surfaces of metals yields highly crystalline films. Section IV outlines the growth of graphene on SiC substrates. This satisfies the requirements for electronic applications, with well-defined graphene-substrate interface, low trapped impurities and no need for transfer. It also allows graphene structures and devices to be measured directly on the growth substrate. The flatness of the substrate results in graphene with minimal strain and ripples on large areas, allowing spectroscopies and surface science to be performed. We also discuss the surface engineering by intercalation of the resulting graphene, its integration with Si-wafers and the production of nanostructures with the desired shape, with no need for patterning. Section V deals with chemical vapour deposition (CVD) onto various transition metals and on insulators. Growth on Ni results in graphitized polycrystalline films. While the thickness of these films can be optimized by controlling the deposition parameters, such as the type of hydrocarbon precursor and temperature, it is difficult to attain single layer graphene (SLG) across large areas, owing to the simultaneous nucleation/growth and solution/precipitation mechanisms. The differing characteristics of polycrystalline Ni films facilitate the growth of graphitic layers at different rates, resulting in regions with differing numbers of graphitic layers. High-quality films can be grown on Cu. Cu is available in a variety of shapes and forms, such as foils, bulks, foams, thin films on other materials and powders, making it attractive for industrial production of large area graphene films. The push to use CVD graphene in applications has also triggered a research line for the direct growth on insulators. The quality of the resulting films is lower than possible to date on metals, but enough, in terms of transmittance and resistivity, for many applications as described in section V. Transfer technologies are the focus of section VI. CVD synthesis of graphene on metals and bottom up molecular approaches require SLG to be transferred to the final target substrates. To have technological impact, the advances in production of high-quality large-area CVD graphene must be commensurate with those on transfer and placement on the final substrates. This is a prerequisite for most applications, such as touch panels, anticorrosion coatings, transparent electrodes and gas sensors etc. New strategies have improved the transferred graphene quality, making CVD graphene a feasible option for CMOS foundries. Methods based on complete etching of the metal substrate in suitable etchants, typically iron chloride, ammonium persulfate, or hydrogen chloride although reliable, are time- and resource-consuming, with damage to graphene and production of metal and etchant residues. Electrochemical delamination in a low-concentration aqueous solution is an alternative. In this case metallic substrates can be reused. Dry transfer is less detrimental for the SLG quality, enabling a deterministic transfer. There is a large range of layered materials (LMs) beyond graphite. Only few of them have been already exfoliated and fully characterized. Section VII deals with the growth of some of these materials. Amongst them, h-BN, transition metal tri- and di-chalcogenides are of paramount importance. The growth of h-BN is at present considered essential for the development of graphene in (opto) electronic applications, as h-BN is ideal as capping layer or substrate. The interesting optical and electronic properties of TMDs also require the development of scalable methods for their production. Large scale growth using chemical/physical vapour deposition or thermal assisted conversion has been thus far limited to a small set, such as h-BN or some TMDs. Heterostructures could also be directly grown. Section VIII discusses advances in GRM functionalization. A broad range of organic molecules can be anchored to the sp(2) basal plane by reductive functionalization. Negatively charged graphene can be prepared in liquid phase (e.g. via intercalation chemistry or electrochemically) and can react with electrophiles. This can be achieved both in dispersion or on substrate. The functional groups of GO can be further derivatized. Graphene can also be noncovalently functionalized, in particular with polycyclic aromatic hydrocarbons that assemble on the sp(2) carbon network by pi-pi stacking. In the liquid phase, this can enhance the colloidal stability of SLG/FLG. Approaches to achieve noncovalent on-substrate functionalization are also discussed, which can chemically dope graphene. Research efforts to derivatize CNMs are also summarized, as well as novel routes to selectively address defect sites. In dispersion, edges are the most dominant defects and can be covalently modified. This enhances colloidal stability without modifying the graphene basal plane. Basal plane point defects can also be modified, passivated and healed in ultra-high vacuum. The decoration of graphene with metal nanoparticles (NPs) has also received considerable attention, as it allows to exploit synergistic effects between NPs and graphene. Decoration can be either achieved chemically or in the gas phase. All LMs, can be functionalized and we summarize emerging approaches to covalently and noncovalently functionalize MoS2 both in the liquid and on substrate. Section IX describes some of the most popular characterization techniques, ranging from optical detection to the measurement of the electronic structure. Microscopies play an important role, although macroscopic techniques are also used for the measurement of the properties of these materials and their devices. Raman spectroscopy is paramount for GRMs, while PL is more adequate for non-graphene LMs (see section IX.2). Liquid based methods result in flakes with different thicknesses and dimensions. The qualification of size and thickness can be achieved using imaging techniques, like scanning probe microscopy (SPM) or transmission electron microscopy (TEM) or spectroscopic techniques. Optical microscopy enables the detection of flakes on suitable surfaces as well as the measurement of optical properties. Characterization of exfoliated materials is essential to improve the GRM metrology for applications and quality control. For grown GRMs, SPM can be used to probe morphological properties, as well as to study growth mechanisms and quality of transfer. More generally, SPM combined with smart measurement protocols in various modes allows one to get obtain information on mechanical properties, surface potential, work functions, electrical properties, or effectiveness of functionalization. Some of the techniques described are suitable for 'in situ' characterization, and can be hosted within the growth chambers. If the diagnosis is made 'ex situ', consideration should be given to the preparation of the samples to avoid contamination. Occasionally cleaning methods have to be used prior to measurement.
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  • Growth of graphitic carbon layers around silicon carbide nanowires

    Mishra, Neeraj   Bosi, Matteo   Rossi, Francesca   Salviati, Giancarlo   Boeckl, John   Iacopi, Francesca  

    We demonstrate the ability to synthesize graphitic carbon sheets around cubic silicon carbide nanowires via an alloy-mediated catalytic process. The transmission electron microscopy analysis shows multilayer graphitic carbon sheets with a large interatomic layer distance of similar to 0.45nm, suggesting the presence of oxygen in the graphitic system. Oxygen-related peaks observed by energy-dispersive X-ray spectroscopy, Raman spectroscopy, and Fourier-transform infrared spectroscopy further confirm the oxidation of the graphitic carbon layers. A detailed investigation of the Raman spectra reveals a turbostratic stacking of the graphitic carbon layers. The turbostratic nature and the presence of oxidation in the graphitic carbon surrounding the silicon carbide nanowires make them a suitable platform for further functionalization, of particular interest for biosensing, as both graphitic carbon and silicon carbide are biocompatible.
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  • Bond graph modeling of a 3-joint string-tube actuated finger prosthesis

    Mishra, Neeraj   Vaz, Anand  

    In prosthetic systems, the mechanism, sensing and actuation systems, and controls are some of the important areas which require modeling and analysis. Causal representation based on power transactions provides better understanding of interactions between these subsystems. A unified approach is therefore required to deal with the dynamics of such systems. Bond graph offers such a unified approach to the dynamics of such biomechanical systems. The concept of Word Bond Graph Objects (WBGOs) provides several advantages in modeling such large systems, including: compact representation; facilitation of understanding of energetic and causal interactions between component subsystems; algorithmic, quick and easy object oriented programming for numerical simulations. The approach had been applied earlier to develop models for a class of hand prosthesis. This work is an elaborate extension to a redundant under-actuated three-joint string-tube based finger prosthesis for a partially impaired hand. It systematically explains the dynamics of behavior of the mechanism, interactions at translational and revolute couplings between rigid phalanges, and, string-tube based joint actuation principles involved in this class of prosthesis through simulations of the bond graph models. (C) 2017 Elsevier Ltd. All rights reserved.
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  • Bond graph modeling of a 3-joint string-tube actuated finger prosthesis

    Mishra, Neeraj   Vaz, Anand  

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  • Graphene growth on silicon carbide: A review

    Mishra, Neeraj   Boeckl, John   Motta, Nunzio   Iacopi, Francesca  

    Graphene has been widely heralded over the last decade as one of the most promising nanomaterials for integrated, miniaturized applications spanning from nanoelectronics, interconnections, thermal management, sensing, to optoelectronics. Graphene grown on silicon carbide is currently the most likely candidate to fulfill this promise. As a matter of fact, the capability to synthesize high-quality graphene over large areas using processes and substrates compatible as much as possible with the well-established semiconductor manufacturing technologies is one crucial requirement. We review here, the enormous scientific and technological advances achieved in terms of epitaxial growth of graphene from thermal decomposition of bulk silicon carbide and the fine control of the graphene electronic properties through intercalation. Finally, we discuss perspectives on epitaxial graphene growth from silicon carbide on silicon, a particularly challenging area that could result in maximum benefit for the integration of graphene with silicon technologies. (C) 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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  • Graphene growth on silicon carbide: A review

    Mishra, Neeraj   Boeckl, John   Motta, Nunzio   Iacopi, Francesca  

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  • Nanoparticulate carrier system:a novel treatment approach for hyperlipidemia

    Sharma, Kritika   Kumar, Kulyash   Mishra, Neeraj  

    Hyperlipidemia is a prevailing risk factor that leads to development and progression of atherosclerosis and consequently cardiovascular diseases. Several antihyperlipidemic drugs are having various disadvantages such as low water solubility and poor bioavailabilty due to presystemic gastrointestinal clearance. Thus, there is a considerable need for the development of efficient delivery methods and carriers. This review focuses on the importance and role of various nanoparticulate systems as carrier for antihyperlipidemic drugs in the treatment of hyperlipidemia. Some nanoparticle technology-based products are approved by FDA for effective treatment of hyperlipidemia, namely Tricor (R) by Abbott Laboratories (Chicago, IL, USA) and Triglide (R) by Skye Pharma (London, UK). Efforts to address each of these issues are going on, and should remain the focus on the future studies and look forward to many more clinical products in the future.
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  • Role of polymer-drug conjugates in organ-specific delivery systems.

    Paramjot   Khan, Nikhat Mansoor   Kapahi, Himani   Kumar, Sahil   Bhardwaj, T R   Arora, Saahil   Mishra, Neeraj  

    Polymers have been utilized to deliver the drug to targeted site in controlled manner, achieving the high-therapeutic efficacy. Polymeric drug conjugates having variable ligands as attachments have been proved to be biodegradable, stimuli sensitive and targeted systems. Numerous polymeric drug conjugates having linkers degraded by acidity or intracellular enzymes or sensitive to over expressed groups of diseased organ/tissue have been synthesized during last decade to develop targeted delivery systems. Most of these organs have number of receptors attached with different cells such as Kupffer cells of liver have mannose-binding receptors while hepatocytes have asialoglycoprotein receptors on their surface which mainly bind with the galactose derivatives. Such ligands can be used for achieving high targeting and intracellular delivery of the drug. This review presents detailed aspects of receptors found in different cells of specific organ and ligands with binding efficiency to these specific receptors. This review highlights the need of further studies on organ-specific polymer-drug conjugates by providing detailed account of polymeric conjugates synthesized till date having organ-specific targeting. =20
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  • Graphene growth on silicon carbide: A review (Phys. Status Solidi A 9∕2016)

    Mishra, Neeraj   Boeckl, John   Motta, Nunzio   Iacopi, Francesca  

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  • Embelin-loaded guar gum microparticles for the management of ulcerative colitis.

    Sharma, Ankita   Kaur, Navneet   Sharma, Saurabh   Sharma, Amit   Rathore, M S   Ajay, Kumar   Mishra, Neeraj  

    The aim of the present study is to develop embelin-loaded guar gum microparticles through emulsification technique. The in vitro release of the optimised formulation was found to be 88.5=C2=B13.8% in 24h, has exhibited remarkably sustain and delayed the release of embelin at a specific site. Embelin-loaded microparticles showed average particle size of 12.9=C2=B10.75m. The statistical analysis was carried out by one-way ANOVA followed by comparison test of Bonferroni. P values <0.05 were considered as significant. The in vivo study concluded that pre-treatment of embelin prevents dinitrobenzenesulfonic acid (DNBS)-induced colitis in rats and depicts protective activity against ulcerative colitis due to its antioxidant and anti-inflammatory actions. This approach produces comparatively less side effect to another conventional dosage form.=20
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  • Pyrolysis of waste polypropylene for the synthesis of carbon nanotubes

    Mishra, Neeraj   Das, Gobind   Ansaldo, Alberto   Genovese, Alessandro   Malerba, Mario   Povia, Mauro   Ricci, Davide   Di Fabrizio, Enzo   Di Zitti, Ermanno   Sharon, Madhuri   Sharon, Maheshwar  

    Waste polypropylene (PP) is used as precursor for synthesizing multi-walled carbon nanotubes (MWCNTs) by single stage chemical vapor deposition (CVD) method using nickel as catalyst. The pyrolytic degradation of PP to MWCNT was achieved by exposing the catalyst and precursor to temperature 600,700 and 800 C under argon and hydrogen atmosphere for an hour. The resultant carbon was purified and characterized by XRD, Raman scattering, SEM, TEM and HRTEM. All the analysis confirmed the graphitic nature and multi-walled morphology of the CNT. Moreover the MWCNT was found to exhibit high transmittance to visible light up to 85% at 550 nm, comparable to that of typical ITO films (90%), suggesting that MWCNTs can be used for optoelectronic devices. The present work could be employed for synthesizing CNTs, having wide range of applications, and for environment protection as well since waste plastic is being used. (C) 2011 Elsevier B.V. All rights reserved.
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  • A generalized search scheme for automatic registration of remote-sensing data

    Ravikanti, Chandrakanth   Mishra, Neeraj   Janjam, Saibaba   Varadan, Geeta  

    A generalized search scheme for automatic registration of level-1 data of multiresolution and multi-sensor remote-sensing data was proposed. The robustness and time efficiency of the automatic registration process is critically dependant on the search scheme for identification of control points. The proposed method consists of three levels of search ranging from coarser to finer. This process was found to be capable of registering images to sub-pixel level which are independent of rotation and scale variations, and also translation that vary by few metres to kilometres. In order to reduce the low pass effect due to multiple transformations involved in the multi-level registration process, a direct correspondence between the reference image and target image was established so that a single resampling needs to be applied. This correspondence also helps to generate products at any desired pixel size and to keep the original resolution intact. In this scheme mutual information (MI) is used as a similarity measure and a non-rigid transformation, thin plate spline (TPS), is used for achieving sub-pixel registration accuracies. MI is found to be better for identification of match points even for images that are radiometrically nonlinear. Unlike global transformation methods, use of non-rigid transformations such as TPS achieves sub-pixel accuracy in the moderate hilly regions as well as high hilly regions where relief displacements are high, provided sufficient number of control points are generated. However TPS transformation demands accurate control points. A robust method for detection of inaccurate control points was adopted and explained in the paper. The scheme was tested on a number of combinations of remote sensing data of the same resolution and different resolution datasets, namely Cartosat-1 with Liss-4 of Resourcesat-1, Landsat Thematic Mapper (TM) with IRS-1C/1D and Cartosat-1 with Enhanced Thematic Mapper (ETM). The results are presented along with accuracies achieved.
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  • Taguchi method optimization of wax production from pyrolysis of waste polypropylene

    Mishra, Neeraj   Patra, Niranjan   Pandey, Sunil   Salerno, Marco   Sharon, Madhuri   Sharon, Maheshwar  

    Present research deals with the conversion of waste commodity plastics to valuable commercial product in the form of wax by pyrolysis. Optimization of both processes yield and produced wax quality was performed by means of a statistical tool originally proposed by G. Taguchi, using temperature, catalyst, carrier gas, and dwell time as the parameters. The obtained wax was characterized by Raman spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. Yield of wax was found to be maximum when the parameters were 600 A degrees C, Fe catalyst, nitrogen gas atmosphere, and 15 min time. However, stability of the wax was found to be optimum at 700 A degrees C. Calorific value of the wax thus obtained was similar to 43 MJ kg(-1), which supports its suitability as fuels like other petroleum products.
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  • A modified approach of impression technique for fabrication of finger prostheses

    Tripathi, Shuchi   Singh, Raghuwar Dayal   Chand, Pooran   Mishra, Neeraj   Yadav, Lakshya Kumar   Singh, Saumyendra Vikram  

    Background and Aim: The custom-made finger prosthesis is aesthetically acceptable and comfortable for use in patients with amputated fingers, resulting in psychological improvement and physiological well being. The success of the prosthesis depends on the precision of planning the prosthesis, making the impression, carving the model and choosing the material that best suits the concerned circumstances. In this article a simplified method was used regarding an accurate impression of partially amputated fingers. Technique: A plastic cylindrical small open container (impression cap) was used for making an impression of the fingers. A wax pattern of the missing part was made by replicating the same fingers of the other hand with melted modelling wax after slight modification. This pattern was finally cured with silicone material. Discussion: In the present technique, a modified approach of impression making was used for getting an accurate fit of the finger prosthesis with improved aesthetics, which is one of the most important criterion for the success of any prosthesis.
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  • A sensitive calorimetric technique to study energy (heat) exchange at the nano-scale

    Basta, Luca   Veronesi, Stefano   Murata, Yuya   Dubois, Zoe   Mishra, Neeraj   Fabbri, Filippo   Coletti, Camilla   Heun, Stefan  

    Every time a chemical reaction occurs, an energy exchange between reactants and the environment takes place, which is defined as the enthalpy of the reaction. During the last few decades, research has resulted in an increasing number of devices at the micro- or nano-scale. Sensors, catalyzers, and energy storage systems are more and more developed as nano-devices which represent the building blocks for commercial macroscopic objects. A general method for the direct evaluation of the energy balance of such systems is not available at present. Calorimetry is a powerful tool to investigate energy exchange, but it usually requires macroscopic sample quantities. Here, we report on the development of an original experimental setup able to detect temperature variations as low as 10 mK in a sample of approximate to 10 ng using a thermometer device having physical dimensions of 5 x 5 mm(2). This technique has been utilized to measure the enthalpy release during the adsorption process of H-2 on titanium-decorated monolayer graphene. The sensitivity of these thermometers is high enough to detect a hydrogen uptake of approximate to 10(-10) moles, corresponding to approximate to 0.2 ng, with an enthalpy release of about 23 J. The experimental setup allows, in perspective, scalability to even smaller sizes.
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  • Embedded Reconfigurable Augmented DC-DC Boost Converter for Fast Transient Recovery

    Mishra, Neeraj   Jha, Niraj   Kapat, Santanu   Patra, Amit  

    A DC-DC boost converter is widely used for power management applications. However, the right-half-plane zero effect still remains a bottleneck for fast transient recovery. This paper is intended to propose an embedded reconfigurable boost converter solution with ultra-fast transient recovery through near-lossless augmentation. This augmentation branch requires an extra synchronous phase in parallel, comprising a small inductor and a half-bridge switch cell. This branch is activated only during large-signal transient recovery. The original converter topology is restored for steady state operations, thereby improving the overall efficiency. A prototype augmented boost converter is tested, and the proposed controller is implemented using an FPGA device. The extra branch closely nullifies current and voltage overshoot/undershoots. It is also expected to have almost no impact on efficiency.
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