Inhomogeneity of CoCrW powder products manufactured by SLM technology

Anna Guzanová,Dagmar Draganovská,Gabriela Ižaríková,Janette Brezinová,Viktória Rajťúková,Jozef Živčák,Radovan Hudák,Erik Janoško,Róbert Moro 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.10

The article deals with selective laser melting process using CoCrW powder. Our aim was to identify the influence of product position on the building platform and the re-use of powder on roughness, hardness, porosity and corrosion properties of materials, made under uniform process parameters. Roughness was tested with a stylus profilometer, corrosion resistance by electrochemical impedance spectroscopy and linear polarization. Porosity was assessed by image analysis on metallographic sections taken in two mutually perpendicular directions. The same metallographic sections were used to measure microhardness. The results confirmed a statistically significant dependence of the surface roughness with the position on the platform as well as with the recycling of the powder used. The corrosion resistance of the materials was excellent. Increased porosity values and lower hardness occurred in the middle of the building platform. The reason for the variation of the properties within the building platform can be seen in the unequal laser input energy in the individual positions of the plate.

Analytical Modelling and Simulation Analysis of Junctionless Nanotube (JL NT) MOSFET

Raj Kumar,Raj Kumar,Arvind Kumar 한국전기전자재료학회 2022 Transactions on Electrical and Electronic Material Vol.23 No.4

In this paper, an analytical model for junctionless nanotube (JLNT) MOSFET has been developed. The analytical model for minimum central potential, threshold voltage and drain current has been developed by using variable separation method. These model expressions are further applied to analyse the Short Channel Effects (SCEs) of JL NT MOSFET. The electrical performance of proposed device has been investigated by varying different process parameters such as silicon nanotube thickness, gate oxide thickness, and gate length. All the results of developed models have been validated by comparing with so obtained simulated results from genius 3D device simulator of VisualTCAD for different device parameters. JLNT MOSFET with appropriate design parameters can be further explored for circuit applications.

Design and Challenges of Banking and Foreign Exchange Regulation in India

( Raj Bhala ) 고려대학교 법학연구원 2015 The Asian Business Lawyer Vol.16 No.-

In the post-British Raj Era, two hallmarks characterize Indian banking law: financial inclusion and financial liberalization. Indian banking law and policy has emphasized incorporation of the unbanked and under-banked as part of an overall development strategy to alleviate poverty. This emphasis has been consistent since 1947. Also since Partition, that law and policy has regulated foreign exchange (FX). But, on this topic India reversed course. In the 1990s, India shifted from Nehruvian Socialiststyle controls to FX liberalization. To some degree, underlying both the consistent emphasis on financial inclusion, and the new turn toward financial liberalization, are long-held suspicions in India about unbridled western-style financial markets. The suspicions may work to India’s long-term advantage. Unchecked financial liberalization may undermine financial inclusion, so a cautionary approach may avoid exacerbating marginalization. Simply put, the principal challenge for Indian banking law and policy is to continue liberalization while furthering inclusion. Can India achieve inclusive liberalization?

Ionic liquid assisted recovery of cobalt and nickel metals from spent lithium-ion batteries (LIBs)

( Raj Tirath ),( Raj Morya ),( Ashutosh Kumar Pandey ),( Sang-hyoun Kim ) 한국폐기물자원순환학회 2022 ISSE 초록집 Vol.2022 No.-

Lithium-ion batteries (LIBs) have become an essential component of the energy supply chain for transportation (in electric vehicles) and renewable energy storage systems. This surge in demand necessitates an increase in production, which, in turn, results in a large number of waste LIBs. LIB cathode material primarily contains heavy metal elements such as nickel (Ni) and cobalt (Co), which are potentially hazardous to human health and the environment if discarded improperly. The leaching of Co and Ni into various water streams has become an environmental hazard and is continuously affecting human health through the food chain. Thus, recycling spent LIBs has gotten a lot of attention because it provides a cost-effective way to ensure a steady supply of these metals for LIB remanufacturing. Thus, recycling spent LIBs has received a lot of attention because it offers a cost-effective way to ensure a steady supply of these metals for LIB remanufacturing while also encouraging safer environmental load reduction. Solvent extraction is the most widely accepted method for separating these metals, but traditional extractants employed in conjunction with molecular diluents often lack selectivity and cause major environmental hurdles. Thus, the present study demonstrated a state-of-the-art approach for the recovery of cobalt and nickel from waste LIBs using green ionic liquids, which is such as recycling from a sustainable perspective. Ionic liquids are molten salts of organic cation and inorganic/ organic anion and are considered as green solvents. Here in, two halogen-free, low viscous, biocompatible fatty acid-based hydrophobic ionic liquids (ILs) were synthesized, characterized, and used to recover cobalt, Co(II), and nickel, Ni(II), from aqueous solutions. The extraction behaviors of Co(II) and Ni(II) were studied further by varying the equilibrium time, ILs molar concentration, metal loading, and temperature. Thermodynamic parameters such as enthalpy change and Gibbs free energy change were also investigated showed that metal recovery is governed by metal transfer phenomenon. Study revealed that fatty acid-based ILs were found to be capable of extracting > 99 % Co(II) and Ni(II) from aqueous solutions at 298 K in 15 minutes using a 1:1 (org: aq.) ratio at low concentrations of 2.5 to 10 g L^-1. Furthermore, when the metal concentration was greater than 10 g L^-1, Co(II) extraction was preferred over Ni(II) extraction for methyltrioctylammonium oleate IL.

Interim palatal lift prosthesis as a constituent of multidisciplinary approach in the treatment of velopharyngeal incompetence

Neerja Raj,Vineet Raj,Himanshu Aeran 대한치과보철학회 2012 The Journal of Advanced Prosthodontics Vol.4 No.4

The velopharynx is a tridimensional muscular valve located between the oral and nasal cavities, consisting of the lateral and posterior pharyngeal walls and the soft palate, and controls the passage of air. Velopharyngeal insufficiency may take place when the velopharyngeal valve is unable to perform its own closing, due to a lack of tissue or lack of proper movement. Treatment options include surgical correction, prosthetic rehabilitation, and speech therapy; though optimal results often require a multidisciplinary approach for the restoration of both anatomical and physiological defect. We report a case of 56 year old male patient presenting with hypernasal speech pattern and velopharyngeal insufficiency secondary to cleft palate which had been surgically corrected 18 years ago. The patient was treated with a combination of speech therapy and palatal lift prosthesis employing interim prostheses in various phases before the insertion of definitive appliance. This phase-wise treatment plan helped to improve patient's compliance and final outcome.

Photocatalytic and antibacterial properties of a TiO₂/nylon-6 electrospun nanocomposite mat containing silver nanoparticles

Pant, Hem Raj,Pandeya, Dipendra Raj,Nam, Ki Taek,Baek, Woo-il,Hong, Seong Tshool,Kim, Hak Yong Elsevier 2011 Journal of hazardous materials Vol.189 No.1

<P><B>Abstract</B></P><P>Silver-impregnated TiO<SUB>2</SUB>/nylon-6 nanocomposite mats exhibit excellent characteristics as a filter media with good photocatalytic and antibacterial properties and durability for repeated use. Silver nanoparticles (NPs) were successfully embedded in electrospun TiO<SUB>2</SUB>/nylon-6 composite nanofibers through the photocatalytic reduction of silver nitrate solution under UV-light irradiation. TiO<SUB>2</SUB> NPs present in nylon-6 solution were able to cause the formation of a high aspect ratio spider-wave-like structure during electrospinning and facilitated the UV photoreduction of AgNO<SUB>3</SUB> to Ag. TEM images, UV–visible and XRD spectra confirmed that monodisperse Ag NPs (approximately 4nm in size) were deposited selectively upon the TiO<SUB>2</SUB> NPs of the prepared nanocomposite mat. The antibacterial property of a TiO<SUB>2</SUB>/nylon-6 composite mat loaded with Ag NPs was tested against <I>Escherichia coli</I>, and the photoactive property was tested against methylene blue. All of the results showed that TiO<SUB>2</SUB>/nylon-6 nanocomposite mats loaded with Ag NPs are more effective than composite mats without Ag NPs. The prepared material has potential as an economically friendly photocatalyst and water filter media because it allows the NPs to be reused.</P>

Electrospun nylon-6 spider-net like nanofiber mat containing TiO₂ nanoparticles: A multifunctional nanocomposite textile material

Pant, Hem Raj,Bajgai, Madhab Prasad,Nam, Ki Taek,Seo, Yun A.,Pandeya, Dipendra Raj,Hong, Seong Tshool,Kim, Hak Yong Elsevier 2011 Journal of hazardous materials Vol.185 No.1

<P><B>Abstract</B></P><P>In this study, electrospun nylon-6 spider-net like nanofiber mats containing TiO<SUB>2</SUB> nanoparticles (TiO<SUB>2</SUB> NPs) were successfully prepared. The nanofiber mats containing TiO<SUB>2</SUB> NPs were characterized by SEM, FE-SEM, TEM, XRD, TGA and EDX analyses. The results revealed that fibers in two distinct sizes (nano and subnano scale) were obtained with the addition of a small amount of TiO<SUB>2</SUB> NPs. In low TiO<SUB>2</SUB> content nanocomposite mats, these nanofiber weaves were found uniformly loaded with TiO<SUB>2</SUB> NPs on their wall. The presence of a small amount of TiO<SUB>2</SUB> NPs in nylon-6 solution was found to improve the hydrophilicity (antifouling effect), mechanical strength, antimicrobial and UV protecting ability of electrospun mats. The resultant nylon-6/TiO<SUB>2</SUB> antimicrobial spider-net like composite mat with antifouling effect may be a potential candidate for future water filter applications, and its improved mechanical strength and UV blocking ability will also make it a potential candidate for protective clothing.</P>

Development of ciclopirox nail lacquer with enhanced permeation and retention

( Raj Kumar Thapa ),( Ju Yeon Choi ),( Toe Gyung Go ),( Min Hyung Kang ),( Sang Duk Han ),( Joon Ho Jun ),( Mi Won Son ),( Chul Soon Yong ),( Jong Oh Kim ) 영남대학교 약품개발연구소 2016 영남대학교 약품개발연구소 연구업적집 Vol.26 No.-

Onychomycosis is a prevailing disease caused by fungal infection of nails that mostly affects athletes and the elderly. Ciclopirox is approved by the US Food and Drug Administration for the topical treatment of ony-chomycosis. However, the desired penetration of ciclopirox into the nail bed has not been achieved via topical appli-cation for efficient treatment. Therefore, the main aim of this study was to enhance ciclopirox permeation and retention in nail by the development of a new nail lacquer formulation. We screened the effects of different solvents, alkalizing agents, and permeation enhancers on the per-meation of bovine hooves by ciclopirox and its retention in human nail clippings. The results suggest that isopropyl alcohol, potassium hydroxide, and urea as the solvent, alkalizing agent, and permeation enhancer, respectively, improved the permeation of the ciclopirox nail lacquer formulation the most with high flux rates. Comparison of the final formulation and marketed product revealed enhanced retention of ciclopirox from our developed for-mulation in human nail clippings. Therefore, our newly developed nail lacquer may be a potentially effective for-mulation for the treatment of onychomycosis in humans.

Graphene oxide-wrapped PEGylated liquid crystalline nanoparticles for effective chemo-photothermal therapy of metastatic prostate cancer cells

( Raj Kumar Thapa ),( Yu Seok Youn ),( Jee Heon Jeong ),( Han Gon Choi ),( Chul Soon Yong ),( Jong Oh Kim ) 영남대학교 약품개발연구소 2016 영남대학교 약품개발연구소 연구업적집 Vol.26 No.-

Here, we report the preparation of PEGylated liquid crystalline nanoparticles (LCN) loaded with docetaxel (DTX) and wrapped with grapheme oxide (GO), called PEG-GO/LCN/DTX, for effective chemo-photothermal therapy of metastatic prostate cancer cells. The prepared formulation exhibited a small particle size(<250 nm), high durg loading capacity(~15%), and efficient near infrared (NIR) light-induced thermal heat. Importantly, PEG-GO/LCN/DTX successfully accumulated in prostate cancer cells and exhib-ited potent apoptotic and actimigration effects, mediated by the combination of the anticancer effects of DTX and the thermal heat induced by exposure of GO to NIR light. Taken together, our findings sup-port that PEG-GO/LCN/DTX may be an effective system for treatment of metastatic prostate cancer. Moreover, the results establish a proof-of-concept for the potential chemo-photothermal functional-ity of PEG-GO/LCN/DTX. This hybrid system of LCN and GO could provide controlled and tatgeted drug delivery with enhanced NIR-induced thermal effects for effective treatment of metastatic cancers.

Research Trends in the Directed Energy Deposition Method of Heterogeneous Materials

Raj Narayan Hajra,Jeoung Han Kim 대한용접·접합학회 2024 대한용접·접합학회지 Vol.42 No.1

Metal Additive Manufacturing (AM) or 3D printing garners attention for economically producing components with superior strength, durability, and corrosion resistance. The microstructure, influenced by factors like heat input, scanning speed, and layer thickness, shapes metal materials intricately in 3D printing.Unlike traditional manufacturing with separate fabrication and post-processing, Multi Materials AM (MM-AM) streamlines the construction of composite structures in a single step using a single machine. Although initial MM-AM, especially inpolymer 3D printing, was simpler, the shift to metal-based MM-AM presents challenges. The distinctive bonding style in MM-AM facilitates robust connections between different metals, minimizing stress concentration and simplifying the joining of diverse metals. Challenges like intermetallic compound formation, residual stress, and material-specific issues leading to cracks persist. Ongoing research focuses on metallurgy, process optimization,and computational simulation to overcome these hurdles. This review delves into current research trends in multi-material AM, identifying pathways for technological advancements. It discusses the application of Directed Energy Deposition (DED)in stacking austenitic and ferritic metals for nuclear power plant cooling system piping’s gradient-form safe-ends. The study emphasizes advanced manufacturing techniques for developing functionally graded materials and dissimilar metal joints, highlighting the transformative potential of additive manufacturing across industries.