Prem Thapa - Academia.edu (original) (raw)

Papers by Prem Thapa

Survey Analysis for Indigenous Policy in Australia: Social Sciences Perspectives, 2012

European Journal of Engineering and Technology Research, 2021

Wireless sensor networks have revolutionized the way healthcare works replacing the traditional m... more Wireless sensor networks have revolutionized the way healthcare works replacing the traditional methods with sensor-enabled IoT devices that help in monitoring the data. The data is collected by these sensors that are there on the body of the user, the data is transmitted over the network to the healthcare monitoring systems. The transmission follows the route of the wireless channel that is not secure as it can be accessed by legitimate as well as illegitimate users. These pose security threats; one such attack is a replication attack. This makes the replicas of the original node, replaces the data with the malicious content for attacking the system, and deploys the node back to the network making it difficult to detect. The aim of the work is to review the Blockchain-based intelligent monitored security system for the detection of replication attacks in the wireless healthcare network. The method used for review is the secondary research method. The main focus of the work is kept ...

Catalysts, 2019

A one-step catalytic process was used to catalyze the hydrodeoxygenation of 5-methyl-3-heptanone ... more A one-step catalytic process was used to catalyze the hydrodeoxygenation of 5-methyl-3-heptanone (C8 ketone) to a mixture of 5-methyl-3-heptene, 5-methyl-2-heptene (C8 alkenes), and 3-methyl heptane (C8 alkane). High conversion of C8 ketone to the desired products was achieved over a single bed of a supported catalyst (bifunctional heterogeneous catalyst) consisting of one transition metal (copper (Cu) or platinum (Pt)) loaded on alumina (Al2O3) under mild operating conditions (reaction temperatures were varied between 180 °C to 260 °C, and the pressure was 1 atm). The C8 ketone was hydrogenated to 5-methyl-3-heptanol (C8 alcohol) over metal sites, followed by dehydration of the latter on acid sites on the support to obtain a mixture of C8 alkenes. These C8 alkenes can be further hydrogenated on metal sites to make a C8 alkane. The results showed that the main products over copper loaded on alumina (20 wt% Cu–Al2O3) were a mixture of C8 alkenes and C8 alkane in different amounts dep...

Energies, 2018

The integration of renewable energies into combined cooling, heating, and power (CCHP) systems ha... more The integration of renewable energies into combined cooling, heating, and power (CCHP) systems has become increasingly popular in recent years. However, the optimization of renewable energies integrated CCHP (RECCHP) systems (i.e., optimal component configurations) is far from being well addressed, especially in isolated mode. This study aims to fill this research gap. A multi-objective optimization model characterizing the system reliability, system cost, and environmental sustainability is constructed. In this model, the objectives include minimization of annual total cost (ATC), carbon dioxide emission (CDE), and loss of energy supply probability (LESP). The decision variables representing the configuration of the RECCHP system include the number of photovoltaic (PV) panels and wind turbines (WTs), the tilt angle of PV panels, the height of WTs, the maximum fuel consumption, and the capacity of battery and heat storage tanks (HSTs). The multi-objective model is solved by a multi-...

Journal of Catalysis, 2018

We demonstrate the use of a green catalyst precursor and oxidant in a modified photo-Fenton proce... more We demonstrate the use of a green catalyst precursor and oxidant in a modified photo-Fenton process for synthesis of efficient Fischer-Tropsch catalysts. The process yields small, stable, and well-dispersed catalyst nanoparticles (Fe or Co) on carbon nanotubes (CNTs) that do not require calcination due to the absence of foreign components (nitrate, chloride, or acetate) that must be removed during postsynthesis treatment. The synthesized catalysts were characterized by X-ray diffraction (XRD), N 2 physisorption, H 2 temperature-programmed reduction (H 2 TPR), Raman spectroscopy, transmission electron microscopy (TEM), and inductively coupled plasma (ICP) spectroscopy. Results showed high catalyst dispersion and smaller catalyst particles with narrow particle-size distributions in comparison to catalysts synthesized by incipient wetness impregnation (IWI). Performance of CNT-supported catalysts (CO conversion, C5+ selectivity, and catalyst lifetime) prepared by the photo-Fenton process was evaluated during Fischer-Tropsch synthesis (FTS) and compared with that of CNT-and SiO 2-supported catalysts synthesized via IWI. In general, a CNT-based Fe or Co catalyst, prepared by the photo-Fenton process, shows a higher performance at a lower FTS reaction temperature (200°C for Co and 250°C for Fe) and a decreased potential for catalyst sintering in comparison with that of conventional catalysts (synthesized via IWI). In particular, a Co catalyst obtained from the photo-Fenton process shows high CO conversion ($80%) and outstanding selectivity for liquid hydrocarbons (C5+; $70%). The process demonstrates a new synthesis route for exploiting outstanding material properties of CNTs in catalysis.

physica status solidi (a), 2017

Zinc oxide (ZnO) nanoparticles (NPs) with uniform particle radius comparable to the desired Debye... more Zinc oxide (ZnO) nanoparticles (NPs) with uniform particle radius comparable to the desired Debye length provide a low-cost and a scalable scheme to achieve optimized electron depletion effect, which is the key to high performance ultraviolet (UV) photodetection. Here, a simple and improved sol-gel method for in situ synthesis of highly crystalline constituent ZnO-NP mesoporous thin films is reported. In combination with optimal oxygen plasma treatment to activate the ZnO-NP surface, the UV-detection performance is enhanced remarkably with a reduced dark current by one order of magnitude and an increased UV detectivity by over 300%. Moreover, such UV photodetector s exhibit extraordinary performance with high responsivity of up to 0.8 A W À1 V À1 at 340 nm UV power of 0.003 mW cm À2 , detectivity of 1.4 Â 10 11 Jones, and rise/decay time of 3.4 s/5.0 s. These results illustrate that the sol-gel ZnO-NP films provide a promising template for highperformance UV detectors to take full advantages of the electron depletion effect.

Journal of functional biomaterials, Jan 26, 2017

Here, we report the synthesis, characterization, and efficacy study of Fe/Fe₃O₄-nanoparticles tha... more Here, we report the synthesis, characterization, and efficacy study of Fe/Fe₃O₄-nanoparticles that were co-labeled with a tumor-homing and membrane-disrupting oligopeptide and the iron-chelator Dp44mT, which belongs to the group of the thiosemicarbazones. Dp44mT and the peptide sequence PLFAERL(D[KLAKLAKKLAKLAK])CGKRK were tethered to the surface of Fe/Fe₃O₄ core/shell nanoparticles by utilizing dopamine-anchors. The 26-mer contains two important sequences, which are the tumor targeting peptide CGKRK, and D[KLAKLAK]₂, known to disrupt the mitochondrial cell walls and to initiate programmed cell death (apoptosis). It is noteworthy that Fe/Fe₃O₄ nanoparticles can also be used for MRI imaging purposes in live mammals. In a first step of this endeavor, the efficacy of this nanoplatform has been tested on the highly metastatic 4T1 breast cancer cell line. At the optimal ratio of PLFAERD[KLAKLAK]₂CGKRK to Dp44mT of 1 to 3.2 at the surface of the dopamine-coated Fe/Fe₃O₄-nanocarrier, the I...

Methods in molecular biology (Clifton, N.J.), 2016

In this chapter we demonstrate a method to produce virus-like particles (VLPs) from Escherichia c... more In this chapter we demonstrate a method to produce virus-like particles (VLPs) from Escherichia coli. Standard bacterial protocols are used for the cloning, transformation, and expression of the protein subunits. A two-step protein purification method is highlighted: one step based on separating soluble proteins with ion-exchange affinity chromatography and a second polishing step using size-exclusion columns to isolate VLP species. The ensuing VLPs can be characterized with a variety of biophysical techniques including ultraviolet (UV)-visible spectroscopy for protein quantification, dynamic light scattering for size distribution determination, and transmission electron microscopy to ascertain size and morphology.

During the last decade, extensive efforts have been made on hydrogenolysis of bio-derived polyols... more During the last decade, extensive efforts have been made on hydrogenolysis of bio-derived polyols to fuels and high value added chemicals using heterogeneous catalysts. The catalysts and processes suffer from low selectivity, harsh reaction conditions and large consumption of expensive hydrogen.[1] Recently a tandom catalysis approach was reported involving hydrogen generation (by reforming of polyols) and instantaneous in situ hydrogenolysis of those polyols to hydrodeoxygenated products on bi-functional supported metal catalysts such as Pt/NaY and Pt/Al2O3.[2,3] This approach does not require addition of external hydrogen but produces useful products even at relatively mild reaction conditions (inert gas pressure < 2 MPa) compared to conventional hydrogenation (hydrogen pressure > 8~10 MPa). However, the selectivity to useful liquid products (S < 60%) is still a major challenge for further improvement. This is because significant amounts of waste gaseous products (S > ...

Polyethylene dioxythiophene nano-filaments were grown on lithographic electrode arrays by the rec... more Polyethylene dioxythiophene nano-filaments were grown on lithographic electrode arrays by the recently developed directed electrochemical nanowire assembly technique. These filaments are firmly attached to the electrode but are not attached to the glass substrate. Hence, they behave like cantilevered rods (with one free end). Individual cells of the slime mold Dictystolium discoideum initiate contact by extending pseudopods to the nanoelectrodes when cultured on the electrode arrays. Scanning electron micrographs of the interfaces show the contact area to be of the order of 0.1 mum^2. Confocal images reveal the focal adhesions in the cell-electrode contact region. Deflection of the nanoelectrode by an individual cell can be used to measure the force exerted by the cell. Recent results on this innovative force sensing approach will be discussed.

The Directed Electrochemical Nanowire Assembly (DENA) technique is a single-step approach to fabr... more The Directed Electrochemical Nanowire Assembly (DENA) technique is a single-step approach to fabricating metallic nanowires and interconnecting them with external circuitry or other objects. Here we expand this technique to include the growth of non-metallic wires. From aqueous pyrrole solutions, individual wires were grown from the tip of one electrode across a 30 mum electrode gap and into contact with

SPIE Proceedings, 2008

Ethylene propylene diene monomer (EPDM) based polymers have been formulated for specific use in p... more Ethylene propylene diene monomer (EPDM) based polymers have been formulated for specific use in photovoltaic modules to produce better performance and longer term stability at a lower cost than standard materials. EPDM formulations are advantageous over ethylene vinyl-acetate (EVA) because they can use the same lamination/cure cycle as EVA, they do not need a second back-sheet protective material (e.g. PET/Tedlar), they have a lower glass transition temperature, no melting transition, more constant mechanical moduli as a function of temperature, they are less polar than EVA (provides better corrosion protection), and they have excellent damp heat (85ºC/85% relative humidity) resistance against delamination. Module designs typically use EVA on the back side of cells despite the fact that transparency is not advantageous. We have developed a single encapsulant layer that will replace standard module back-sheet constructions consisting of EVA/PET/Tedlar. Because a single low-cost material layer is used, it will provide a significant materials cost savings of about 6to6 to 6to8/m 2 as compared to traditional back-sheets. Electrical insulation tests were conducted using 0.85 mm thick stainless steel sheets as a model for a cell. It was found that a polymer layer thickness of about 0.33mm provided better high voltage electrical insulation than a combined film of Tedlar™ (0.038 mm) / PET (0.051 mm) / EVA (0.55 mm). When formulated with a white pigment, reflectivity was comparable to Tedlar TM. Upon accelerated exposure to light at 60C and 60% RH it was found that an EVA layer in front of these materials would decompose before significant yellowing and delamination of the back EPDM layer occurs. Glass EPDM Glass Superstrate on Glass Superstrate on Glass Cells Edge seal J-Box Glass EPDM Glass Cells Edge seal J-Box Figure 10. Schematic of a superstrate thin film module laminated with EPDM. Alternatively, thin film PV cells can be constructed on metal foils. Construction schemes requiring a hermitic package may use a glass front sheet, edge seals, and a back-sheet made of either glass or an aluminum foil containing composite (Fig. 11). Using EPDM with aluminum foil can provide the same electrical insulation in a more robust package at a significant cost savings.

Journal of Pharmaceutical Sciences, 2015

The structural integrity and conformational stability of a genetically modified live, oncolytic h... more The structural integrity and conformational stability of a genetically modified live, oncolytic herpes simplex virus (o-HSV) were investigated across a wide pH (5.5-8.0) and temperature (10 • C-87.5 • C) range. A combination of circular dichroism, intrinsic and extrinsic fluorescence, and static light scattering results was visualized using an empirical phase diagram approach to provide a global assessment of physical stability. Distinct phases were identified including the native state of the virus, an intermediate phase that could represent gradual swelling and/or shedding of the viral envelope, and a highly disrupted, aggregated phase. The nature of these altered forms of the virus was further evaluated by transmission electron microscopy and viral plaque assays. The effect of freeze-thaw (F/T) stress on o-HSV was also examined. After one F/T cycle, a loss of infectious virus titers was observed. In addition, the monomeric virus particle concentration decreased during F/T stress, whereas there was a concurrent increase in larger particles (2-10 m). The comprehensive biophysical characterization of viral stability conducted in this study identified major degradation events leading to loss of infectivity of o-HSV and represents an important step toward stabilization of the virus against thermal and F/T stresses.

This paper studies the effects within Indonesia of subsidies on rice consumption. It does sousing... more This paper studies the effects within Indonesia of subsidies on rice consumption. It does sousing a general equilibrium model of the Indonesian economy, known as WAYANG, whichdistinguishes ten Indonesian households and is designed to give special attention to the incomedistributional impact of policy changes. The analysis shows how general equilibrium modelslike WAYANG can be used to derive the distributional effects

The Journal of Physical Chemistry B, 2014

Fast drug delivery is very important to utilize drug molecules that are short lived under physiol... more Fast drug delivery is very important to utilize drug molecules that are short lived under physiological conditions. Techniques that can release model molecules under physiological conditions could play an important role to discover the pharmacokinetics of short lived substances in the body. Here an experimental method is developed for the fast release of the liposomes' payload without a significant increase in (local) temperatures. This goal is achieved by using short magnetic pulses to disrupt the lipid bilayer of liposomes loaded with magnetic nanoparticles. The drug release has been tested by two independent assays. The first assay relies on the AC impedance measurements of MgSO 4 released from the magnetic liposomes. The second standard release assay is based on the increase of the fluorescence signal from 5(6)-Carboxyfluorescein dye when it the dye is released from the magneto liposomes. The efficiency of drug release ranges from a few percent to up to 40% in case of the MgSO 4. The experiments also indicate that the magnetic nanoparticle generate ultrasound, which is assumed to have a role in the release of the model drugs from the magneto liposomes.

Indonesia in a Reforming World Economy

Compositions suitable for use as encapsulants are described. The inventive compositions include a... more Compositions suitable for use as encapsulants are described. The inventive compositions include a high molecular weight polymeric material, a curing agent, an inorganic compound, and a coupling agent. Optional elements include adhesion promoting agents, colorants, antioxidants, and UV absorbers. The compositions have desirable diffusivity properties, making them suitable for use in devices in which a substantial blocking of moisture ingress is desired, such as photovoltaic (PV) modules.

Encapsulant materials are used in a variety of applications to isolate components, areas, or othe... more Encapsulant materials are used in a variety of applications to isolate components, areas, or other materials from potentially stressful conditions that can adversely affect the performance of a device.

One important indicator of the successful assimilation of immigrants is the comparison of the rel... more One important indicator of the successful assimilation of immigrants is the comparison of the relative success of immigrants and of the native born population in finding employment under different macro economic regimes that affect the overall rate of unemployment in an economy. This paper analyzes the "risk" of unemployment of male immigrants to Australia relative to the native born for two different time periods in which the overall labour market characteristics and the pool of immigrants differ considerably. The two data sets used are the 1990 Income and Housing Costs Survey conducted by the Australian Bureau of Statistics and the first wave of the Household Income and Labour Dynamics in Australia (HILDA) survey whose data refer primarily to the 2001 calendar year. The paper analyzes the correlates of unemployment at the individual level using logistic and probit regression models. It uses both a standard specification of the probability of being unemployed determined b...