Scientific World

Published by Nepal Journals Online
Print ISSN: 1996-8949
Some solutions of the Maxwell equations with Dirac particles for the source in FRW spacetime are discussed. The Green's function of the equation for the radial component of the Maxwell fields, F_{r\eta} and F_{\theta\phi} is solved. Green's function is found to reduce to that of Minkowskian spacetime in the appropriate limit. Also, the Lienard-Wiechert type solution is derived. Also, the solutions with the Dirac particle current is also presented. It is found that the F_{r\eta} is composed of even angular momentum states while the odd states constitue F_{\theta\phi} .
The corrosion monitoring of galvanized steel in 1 h wet and 7 h dry cyclic condition in 0.05 M NaCl has been carried out using AC impedance technique. During the wet-dry cycles, the polarization resistance, R p , and solution resistance, R s , were continuously monitored. The instantaneous corrosion rate of the coating was estimated from the obtained R p -1 and time of wetness (TOW) was determined from the R s values. The corrosion potential, E corr , was measured twice a day during the immersion period of wet-dry cycle. The corrosion was accelerated by the wet-dry cycles in the early stage followed by a decrease in the final stage of wet-dry cycle. The corrosion potential shifted to more negative direction for the first 8 cycles due to dissolution of air formed oxide. A gradual shift in the corrosion potential with the progress of corrosion in the later stage of the wet-dry cycle was observed due to deposition of corrosion products. The corrosion mechanism of galvanized steel is discussed based on the results of corrosion monitoring and corrosion potential variation. Key words: Atmospheric corrosion; Galvanized steel; AC Impedance; Corrosion rate. DOI: 10.3126/sw.v8i8.3855 Scientific World Vol.8(8) 2010 pp.76-80
We present a study of spin vector orientations of 44749 r-magnitude SDSS (Sloan Digital Sky Survey) galaxies having redshift 0.10 to 0.11. The r -magnitudes are observed through 616.5 nm CCD (charge coupled device) filter attached to SDSS telescope located at New Mexico, USA. We have converted two dimensional data to three dimensional galaxy rotation axes. Our aim is to find out non-random effects in the spatial orientation of galaxies. In addition, we wanted to check r-magnitude dependence in the spatial orientation. The expected isotropy distribution curves are obtained by removing the selection effects and performing a random simulation method. In general, spin vector orientations of galaxies is found to be random, supporting Hierarchy model of galaxy formation. A local anisotropy is observed in few samples suggesting a gravitational tidal interaction between neighbor galaxies.
Ternary amorphous W–xCr–yZr alloys containing 9--38 at % tungsten, 15--42 at % chromium and 39--73 at % zirconium were successfully prepared by direct current (DC) magnetron sputtering technique. The corrosion rates of all the examined sputter-deposited W–xCr–yZr alloys were in the range of 1 × 10−3 mm/y or lower which are nearly one order of magnitude lower than those of the sputter-deposited tungsten, chromium and zirconium metals after immersion for 240 h in 0.5 M NaCl solution open to air at 25°C. In particular, the simultaneous additions of tungsten, chromium and zirconium to the amorphous ternary W–xCr–yZr alloys in the chromium- and zirconium-enriched W--91Cr and W--88Zr alloys, respectively, showed a synergistic effects for showing the higher corrosion resistance than those of binary WCr and W--Zr alloys in neutral NaCl solution. Keywords : W–Cr–Zr alloys; Sputter deposition; Corrosion test; Open circuit potential; 0.5 M NaCl DOI: SW 2011; 9(9): 34-38
Changes in corrosion rates of the sputter-deposited W-Mo alloys including tungsten and molybdenum in 0.5 M NaCl solution at 25°C, as a function of molybdenum content. 
Changes in open circuit corrosion potentials for the sputter-deposited W-Mo alloys including tungsten in 0.5 M NaCl solution at 25°C, as a function of immersion time. 
The potentiostatic polarization curve of the W-83Mo alloy in 0.5 M NaCl solution at 25 o C. 
The passivation behavior of the sputter-deposited W-xMo alloys was studied in 0.5 M NaCl solution open to air at 25°C using immersion tests and electrochemical measurements. Corrosion rates of the W-xMo alloys containing less than 50 at% molybdenum content are in the range of 1.7-2.0 x10 -2 mm/y and are slightly lower than that of tungsten metal whereas the corrosion rates of the alloys containing more than 50 at% molybdenum increased with the addition of molybdenum in the alloys. The W-83Mo alloy showed active-passive transition and transpassive dissolution. The open circuit potential of all the examined W-xMo alloys is shifted to noble direction with the addition of molybdenum content in the alloys. Scientific World, Vol. 10, No. 10, July 2012 p29-32 DOI:
An attempt was made to enhance the oxygen evolution efficiency in seawater electrolysis by the addition of tin, antimony and molybdenum to Mn-W oxide electrocatalysts prepared by anodic deposition on the intermediate Ir1-x-ySnyO2+0.5y/Ti electrode. Ir1-x-ySnyO2+0.5y/Ti supported nanocrystalline γ-MnO2 type Mn-W-X-O(X=Sn,Sb,Mo) electrocatalysts with grain size of about 5-11 nm were tailored by anodic deposition. All the examined Mn-W-X(X=Sn,Sb,Mo)- O anodes showed the almost 100% oxygen evolution efficiency at 1000 A.m-2 in 0.5 M NaCl solution of pH 1 at 25°C. They guaranteed the stable anode performance of about 99.75-99.85% oxygen evolution efficiencies for more than five months. Keywords: Global warming; CO2 recycling; Oxygen evolution anode; Seawater electrolysis; Hydrogen production electrode. DOI: 10.3126/sw.v8i8.3844 Scientific World Vol.8(8) 2010 pp.39-43
This paper presents the search for substructures within the Supercluster S [227+006+0078]. To use the spectroscopic database (7th data release) of galaxies, studied the number density, all-sky distribution, and redshift maps to identify substructures based on their richness and compactness. And also to find out the substructures within the Supercluster, using the contour plot of number densities of galaxies within the appropriate radius values and number of nearby galaxies.
Ultrasonic velocity and density were measured for the binary systems: polyvinylchloride—cyclohexanone and polyvinylchloride–1,4-dioxane. And hence, the acoustic impedance (Z) and reciprocal of adiabatic compressibility (?-1) were computed. The variations of ultrasonic velocity, density and acoustic impedance with concentration of polyvinylchloride were studied; confirming the absence of solute–solvent interaction.Scientific World, Vol. 12, No. 12, September 2014, page 62-64
We present a study of relative flux density in and around the planet Jupiter using images taken from National Observatory located at Nagarkot, Nepal during the period from November, 2008 and January, 2010. For this Meade 16 inch LX200GPS Schmidt-Cassegrain telescope is used. We processed the image in the software ALADIN2.5. The values of relative flux density of 2,50,000 pixels are used for the study. At first, the observed two-dimensional image of the planet is divided into four quadrants. Each quadrant is subdivided into three sections. We studied the variation of relative flux density along 12 directions. The relative flux density per pixel is found to lie in the range 138.17 to 157.36. The maximum value of relative flux density per pixel is found along the eastern direction and the minimum value is found along the northern direction. Thus the absorption feature is found to be prominent along the northern direction. The emission of less amount of flux from the second quadrant is due to the absorption by the materials in this section. In addition, the role of the inhomogeneous absorption by the on-going gravitational contraction in the planet cannot be identified. Due to the inhomogeneous absorption feature, we studied the outer contours of all sections. The values of total amount of flux per pixel in the outer layers of the first, second, third and fourth quadrants are found to be 81.79, 82.37, 82.44 and 82.49 respectively. Surprisingly, this value is found to be least in the first quadrant. This suggests that the outer part is found to be selective whereas the inner part is emissive. Key-words: Observation; Telescope; Jupiter; Flux density. DOI: 10.3126/sw.v8i8.3838 Scientific World Vol.8(8) 2010 pp.4-9
This paper aims to integrate novel coronavirus daily cases in SAARC countries; India, Pakistan, Bangladesh, Nepal, Sri Lanka, Afghanistan, Maldives and Bhutan to forecast the epidemic trend of COVID-19 by using logistic model. The recent trend of coronavirus cases were analyzed from the COVID-19 epidemiological data for SAARC countries from 23 January 2020 to 31 May 2021. The final size, growth rate parameter and point of inflection of COVID-19 for each countries were calculated by fitting the logistic curve with the cumulative cases. The graphical patterns of COVID-19 daily cases reflect that its second wave impact is more devastating than the first wave in SAARC countries. The increasing trend of COVID-19 cases in these countries was well described by logistic model with coefficient of determination greater than 0.96. The predictive final size of the second wave infections is maximum for India which is 19.8 million with growth rate parameter of 0.08 and inflection time of 68 days whereas the predictive final size is minimum for Afghanistan which is 0.041 million with growth rate parameter of 0.06 and inflection time of 71 days. The logistic model is helpful in predicting the trajectory of the infected cases in a country if the current scenario of this type of infectious disease remains same. Also, it helps the government to frame policy decisions and necessary actions that controls the transmission of COVID-19 in the South Asian region.
To evaluate the accuracy of radiation dose delivered to the cancer patients by using HDR Brachytherapy and to know proposed methods for the initial source installation tests, acceptance testing and a quality assurance program are done on Nucletron MicroSelectron 192Ir HDR Brachytherapy Afterloader at NAMS, Bir Hospital. The observation of sweet spots (maximum dose distribution) by using well chamber (SI HDR 1000) and electrometer (SI CDX 2000). On the basis of the observed sweet spot, Air Kerma Strength of the source is determined. Beside this includes the conformation of step size, radioactivity of the nuclides and safety measures of the machine. A careful radiation survey has been undertaken around the brachytherapy by using well calibrated TBM-IC Mark V is a small ion chamber radiation monitor. Acceptance testing and commissioning of the HDR brachytherapy unit has been completed. Air Kerma strength in newly installed source exhibit small variation but within the limit. The step size has standard deviation 0.05 with the planned step size. The measurement of radiation level around brachytherapy shows the level is within the criteria. Nucletron MicroSelectron 192Ir HDR brachytherapy system has been implemented in our unit. The acceptance test shows that status of brachytherapy and its components are functioning well. Radiation dose which will be delivered to the cancer patients are within planned dose.Scientific World, Vol. 12, No. 12, September 2014, page 85-88
A systematic search at far infrared wavelength in IRAS (Infrared Astronomical Satellite) survey using Groningen Server is performed and investigated a new symmetrical far-infrared (~3° x 2°) filamentary emission at R.A. (J2000) = 21h28m51s and Dec. (J2000) = -33°53'23''. The softwares ALADIN2.5 and ASTROLINUX5.0 are used for the data reduction. We have performed multiwavelength study in the region of interest. The physical properties, flux density, temperature and mass of the nebula are estimated and discussed. In the multiwavelength study, the optical and ultraviolet emission is found to be negligible. A significant far infrared emission is noticed. The radio and X-ray emission is observed to be moderate. It is found that there is a maxima in each filaments, that can clearly seen in 60 μm and 100 μm wavelengths. This indicates that the structure is nearby and a strong external force is influencing its shape. No star is forming in our region of interest. Our symmetrical far infrared nebula belongs to category II type cloud, appearing as diffuse emission of nearly faint optical surface brightness but showing a clumpy structure with no star forming. Total mass of the gas of our nebula is found to lie in the range 1.275 - 3.000 x 10 3 M sun . This estimation is based on the results of flux density study assuming a distance 150±50 pc and dust color temperature 25±5 K. Key Words : Interstellar Medium; Stars; Nebula; Infrared Emission. DOI: 10.3126/sw.v7i7.3815 Scientific World Vol.7(7) 2009 pp.3-9
In this paper, we discussed about the dusty environment of the far infrared cavity around the AGB star located at R.A. (J2000) =01h41m 01s and Dec (J2000) = 71° 04’ 00 9, lying within far infrared loop G125+09 6 in the far infrared IRAS maps. A cavity like structure (major diameter ∼2.55pc & minor diameter ∼0.77pc) is found to lie at R.A. (J2000) = 01h46m57.2s and DEC (J2000) = 71°24’57.1”, located at a distance ∼ 220pc from the star. We studied the distribution of flux density, dust color temperature, dust mass, visual extinction in the cavity. We further studied the distribution Planck function along extension and compression, distribution of dust color temperature along square of the major and minor diameters. The dust color temperature is found to lie in the range (19.7±1.25) K to (21.1±0.55)K which shows the cavity is isolated and stable. A possible explanation of the results will be discussed.
Removal of heavy metals is very important in wastewater treatment process, due to their toxic effects on the environment. Biological treatment has attracted researchers for years since it has many advantages over physical and chemical methods for removing heavy metals from wastewater. The purpose of this research was to assess the biosorption of Cd2+ by wildtype (WT) and CdR-99 resistant line of Chlorella vulgaris confirming mechanisms of resistance to Cd2+ toxicity and the effect of the variable concentrations of Cd2+ on their growth. Exposure of both algal cell lines to increasing Cd2+ concentrations resulted in progressive inhibition of growth as revealed by growth experiments. The higher ID50 value (38 μM Cd2+) of CdR-99 resistant line exhibited some degree of resistance to Cd2+ toxicity. Metal content was determined by flame atomic absorption spectrometry (FAAS). When exposed to the growth medium containing 50 μM Cd2+, CdR-99 resistant isolate proved to be efficient cell line compared to the WT, in terms of adsorption and removal of Cd2+ at 15 min and 48 hr interval of time respectively. Extracellular Cd2+ adsorption was found significantly higher than intracellular uptake in both the tested cell lines. Total Cd2+ accumulation and distribution between the external and internal cell fractions of the CdR-99 were significantly higher to the WT. Thus, the CdR-99 cell line appeared more resistant to Cd2+ toxicity and hence may be used for wastewater treatment and remediation of metal contaminated sites.
FITS image captured by 16" LX200GPS SchmidtCassegrain telescope.
Scientific World, Vol. 11, No. 11, July 2013, page 8-12 DOI:
Present study deals with the preparation of activated carbons from banana peels. The banana peels were subjected to pyrolysis at 700 ℃ for 1 hour in open air (O2-BP), nitrogen gas (N2-BP) and mixture of nitrogen gas and water steam generated to 60-70 ℃ (N2+H2O-BP). The raw and activated carbons from banana peels were characterized by XRD, FTIR and methylene blue adsorption methods.The N2+H2O-BP was used for the adsorption of As (III) ions from aqueous solution. Various parameters affecting the adsorption process like pH (4 to 10), contact time and initial metal ion concentration were varied during the adsorption process. The optimum pH for As (III) adsorption was at 7. An equilibrium time of 2 hours was required for adsorption of As (III) ion. The adsorption isotherms were determined by using Langmuir and Freundlich isotherms and the experimental data were better fitted to Langmuir equation with high coefficient of determination value (R2 = 0.9934). The experimental data fitted well to pseudo second order kinetic model with rate constant value of 0.0111 g/ (mg˖min). The adsorption of As (III) on banana peels was spontaneous and followed physiosorption mechanism. The value of separation parameters (RL) was found to be 0 < RL > 1 for all initial As(III) ion concentrations showed good adsorption of As(III) into banana peels.
Anisotropic wet chemical etching of silicon in alkaline solutions (KOH) is one of the key techniques for the manufacture of microstructure. Fabrication of Micro-electro mechanical system (MEMS) part demand smooth surface finish and angular dependent etch rate. The absolute values of orientation dependent etch rate is found to vary with thermal agitation. In this work, experimental results of etch rate is found with their unusual values of activation energy along different planes. The various sites that an atom can occupy are not equivalent of their energy; some are more favorable to removal than others. In this paper attention is being given to demonstrate thermal activation is the prime factor that influences the behavior of etching mechanism as well as surface morphology. Atomic force microscopy (AFM) has been employed to analyze the morphology of the etched silicon surface at relevant elevated temperature. A systematic variation in morphological growth leads to stabilized surface structure under the influence of associated activation energy. Keywords: Activation energy; Etching; Anisotropy; Etch rate; MEMS; LPCVD; SOI. DOI: 10.3126/sw.v7i7.3817 Scientific World Vol.7(7) 2009 pp.15-18
The plant kingdom is a wide field to search for natural effective antioxidant and oral hypoglycaemic agents that have slight or no side effects. The present study was carried out to analyze the phytochemical, antioxidant and anti-diabetic activities of six ethno-medical plants of Nepal viz Berberis aristata, Murraya koenigii, Xanthium strumarium, Cuscuta reflexa, Myrica esculenta and Syzygium cumini. Phytochemical screening of methanolic extract of all selected plants showed the presence of different chemical constituents such as alkaloids, polyphenols, flavonoids, terpenoids, saponins, glycosides and tanins. The antioxidant activity was evaluated by 2, 2-diphenyl-1-picryl hydrazyl (DPPH) free radical scavenging activity. Ascorbic acid was used as standard during DPPH assay. S. cumini and M. esculenta were seen most active with IC50 values 33.35 µg/mL, 35.19 µg/mL, respectively. The anti-diabetic activity was evaluated by using α-amylase inhibition method. Acarbose was used as positive control during the assay. X. strumarium, S. cumini, M. esculenta, B. aristata were found to be potent towards α-amylase inhibition with IC50 values 197.21 µg/mL, 206.22 µg/mL, 246.07 µg/mL, 270.04 µg/mL.
Drymaria diandra is used in Nepalese traditional medicine to treat various ailments. The hexane, dichloromethane, ethyl acetate, methanol and 50% aqueous methanol extracts of D. diandra were prepared and screened for the presence of different classes of phytochemicals. Methanol and 50% aqueous methanol extracts showed the presence of phenolics, flavonoids and carbohydrates so their total contents were estimated. The highest amount of phenolics and flavonoids were found in methanol extract (190.58±2.21 mg GAE/g extract and 69.25±7.91 mg CE/g extract respectively). The highest amount of sugar was found in 50% methanol extract (185.60±2.53 mg GE/g extract). Similarly, the extracts were tested for the antibacterial activity against one gram negative bacteria, Escherichia coli and one gram positive bacteria Staphylococcus aureus. All the tested extracts showed good antibacterial activity against both bacteria with the inhibition zone ranging from 10 -22 mm. The free radical scavenging activity was determined using DPPH free radical. Both methanol and 50% aqueous methanol extracts showed strong antioxidant activity (IC50 13.61 and 16.94 μg/ml respectively). The GC-MS analysis of hexane extract revealed the presence of more than 22 compounds. However, 9 compounds were identified by comparing the mass fragmentation pattern of each compound with the standard NIST mass spectral database
In the central Himalaya, plants are subjected to a prolonged dry period, thus developing moisture stress. Variations in water relations and their response to drought in a Himalayan tree species, Schima wallichii at 1400 m elevation were studied at Phulchowki Hill, Kathmandu, Nepal. To understand the adaptational strategy of this species through which it withstands water stress, different parameters such as soil water potential at 15 (Y15) and 30 (Y30) cm depths, tree water potential at predawn (Ypd) and midday (Ymd), leaf conductance during morning (gw AM) and afternoon (gw PM) and correlation between all these variables were measured from December 1998 to April 2001, except during monsoon months. There was significant variation among months and years in Ypd, Ymd, AM and gwPM. Mean Ypd and Ymd were -0.20 and –0.63 MPa, respectively. The minimum Y value was observed in March 1999, after 4 months of unusually no rainfall. Some patterns of Ypd were related to phenology and leaf damage as Ypd often increased during leafing. Mean gw AM and gw PM were 95 and 75 m molm–2s–1, respectively. Schima wallichii maintained high Y, with low stomatal conductance reflecting its inherent dehydration postponement adaptation..Scientific World, Vol. 12, No. 12, September 2014, page 79-84
Test methods employed for the study of physio-chemical parameters S.N. Test Parameter ASTM Method
Results obtained by complexometric and pH metric titration methods
A mixed metal oxide (CuO-ZnO) additives has been successfully synthesized in laboratory by co-precipitation technique. The optimum ratio of CuO and ZnO in mixed metal oxide was found to be 1:1. The sodium lauryl sulfate (SLS) has been used as surfactant. The obtained material was found to be crystalline having crystalline size of 18 nm. The stretching band in FTIR spectra at around 1072 cm-1 to 750 cm-1 and around 600 cm-1 indicates the presence of Zn-O and Cu-O bonds. As prepared nano-particles have been used as nano additive in base oil to improve physio-chemical parameters of lubricants. The results revealed that the additive blended base oil (lubricant) has shown excellent lubrication properties. The higher kinematic viscosity of 33.0504 and 6.0158 at 40°C and 100°C respectively showed that as prepared additive blended lubricant is of ISO-32 category according to ISO grading system for lubricants. Similarly, viscosity index was found to be improved from 101 to 129. The pour point was found to be significantly decreased from -6°C to -24°C. So it can be used as good pour point depressant and could be used even in the extreme cold environment condition. The flash point was found to be increased from 215°C to 220°C indicating that the prepared mixed metal oxide (CuO-ZnO) acts as flash point enhancer. The copper strip corrosion rating was found to be 1b for additive indicating the non corrosive nature. The absence of moisture and pH around the neutral range 6.18 showed the additive blended lubricant is not harmful for machinery devices.
Zinc oxide (ZnO) nano additives were successfully synthesized in laboratory by precipitation technique. The XRD showed crystalline nature of ZnO with the average crystallite size of 16 nm. The stretching band of ZnO was found at around 400 cm-1 to 600 cm-1 wave number in FTIR. The prepared nano particle have been used as nano additive and sodium lauryl sulphate (SLS) as surfactant, in base oil to improve physio-chemical parameter of lubricants. The result revealed that the additive blended base oil (lubricant) has shown excellent lubrication properties. The higher kinematic viscosity of 90.72 and 10.40 were obtained at 40oC and 100o C respectively. Similarly, viscosity index were found to be 96 which was improved indicating the use of lubricant in slightly high temperature is possible. The pour point was found to be decreased to -9.2oC which was quite significant and could be used in cold environment. The flash point was also found to be increased from 225o C to 230oC which indicated that the prepared nano additive ZnO acts as flash point enhancer. The corrosion test done by copper strip comparative method and was found to be 1b for additive indicating the non-corrosive nature. The absence of moisture and pH around the neutral range 6.65 showed that the additive blended lubricant is not harmful for machinery devices.
Antimicrobial activity of invasive alien plant species Ageratina adenophora (Sprengel) R. King & H. Robinson was evaluated against six human pathogenic bacteria. The aqueous (distilled water) and alcoholic (methanol) crude extracts from the leaves of the plant were tested against three gram negative bacteria: Escherichia coli (ATCC 25922), Klebsiella pneumoniaea (ATCC 15380) and Proteus mirabilis (ATCC 49132) and three gram positive bacteria: Enterococcus faecalis (ATCC29212) Bacillus subtilis (ATCC6633) and Staphylococcus aureus (ATCC 25923) using disc diffusion method. Different concentrations of plant extracts (5, 10, 15, 20 and 25%) were applied and diameter of zone of inhibition (ZOI) of bacterial growth were recorded. Plant extract in both solvent exhibited pronounced results against tested bacteria. Methanolic extract of plant exhibited good activity against tested bacteria when compared with aqueous extract. The zone of inhibition of bacterial growth increased with increasing concentrations. Phytochemical screening of plant exhibited alkaloids, saponin, tannin and flavonoids and plant sample contains higher amount of alkaloid. The demonstration of activity against all tested organisms had shown that Ageratina adenophora can be used to produce raw materials/substances for further development of diverse antibiotics with broad spectrum of activity.
The present paper includes a list of 69 species of wild mushrooms collected from Sagarmatha National Park (SNP) and its adjoining areas, which are recorded for the first time from this area. Key words: Mushrooms ; Mixed forest; Khumbu region. DOI: 10.3126/sw.v5i5.2659 Scientific World , Vol. 5, No. 5, July 2007 67-74
The dry spinach leaves fine powder was modified by activation with conc. H2SO4 and the adsorbent material was then characterized by using FTIR, EDX, optical microscopy, XRD analysis and methylene blue adsorption method. The EDX result showed about 95 % carbon in the adsorbent material. The maximum specific surface area measured was 499 m2/g. The weak and broad XRD diffraction peaks at 2θ angles 20.5 and 42° were characterized as of activated carbon with the appearance of sharp peak of SiO2 at 2θ angle 26.37°. Optical microscopy Image analysis showed the Porous nature of adsorbents. The adsorption of arsenite on the modified spinach leaves powder adsorbent was investigated by varying different experimental parameters such as pH, adsorbent dose, contact time and As (Ⅲ) ion concentration. The adsorption process was found to be best fitted to Langmuir adsorption isotherm model controlled by pseudo-second–order kinetics with the rate constant value 0.01830 g/(mg·min). The maximum adsorption was observed at pH 6 at room temperature. The maximum adsorption capacity for As (Ⅲ) on modified spinach leaves powder was found to be 58.480 mg/g. The value of ∆G was -22 kJ/mole which confirmed the adsorption process was favored by physisorption. The slope of the linear plot of Qt vs t0.5 was linear but not passed through the origin, which indicates that, the intraparticle diffusion was not only rate controlling step.
The low cost adsorbents were prepared from raw rice husk (RRH) and NaOH treated rice husk (NRH). Then prepared materials were characterized by XRD, FTIR and surface area of rice husk adsorbent were determined by methylene blue adsorption method. XRD showed amorphous nature with low crystallinity of the material. The FTIR spectra showed the presence of oxygenated functional groups such as ester, phenol, carbonyl and silica on the material. The surface area of RRH and NRH were found to be 387 and 417 m2/g respectively. Thus, prepared adsorbents were used for the removal of Fe(II) ion from aqueous solution. The influence of various parameters like pH, adsorbent doge, and contact time were studied for the better adsorption of Fe(II) on rice husk adsorbents. Results revealed that the maximum efficiency was achieved at pH 3 for Fe(II). The adsorption process was found to be best fitted to Langmuir adsorption isotherm model controlled by pseudo-second–order kinetics with the rate constant value i.e. 0.0218 and 0.0235 g/(mg·min) for RRH and NRH respectively. The χ2 values of pseudo second order was found to be lower which confirmed chemisorption, involving ion exchange and valence forces through sharing or exchange of electrons between adsorbent and adsorbate. The maximum adsorption capacity for Fe(II) on RRH and NRH was found to be 2.9 mg/g and 5.6 mg/g respectively. The positive ∆G value represents the randomness of the system during adsorption process. The slope of the linear plot of Qt vs t0.5 was linear but not passed through the origin, which indicates that, the intraparticle diffusion was not only rate controlling step. Temkin value showed the maximum binding energy (KT) for NRH was 16.4 L/g and for RRH it was 12.2 L/g.
In this work both linear and nonlinear advection-diffusion equations are considered and discussed their analytical solutions with different initial and boundary conditions. The work of Ogata and Banks, Harleman and Rumer, Cleary and Adrian, Atul Kumar et al., Mojtabi and Deville are reviewed for linear advection-diffusion equations and for nonlinear, we have chosen the work of Sakai and Kimura. Some enthusiastic functions used in the articles, drawbacks and applications of the results are discussed. Reduction of the advection-diffusion equations into diffusion equations make the governing equation solvable by using integral transform method for analytical solution. For nonlinear advection-diffusion equations, the Cole-Hopf transformation is used to reduce into the diffusion equation. Different dispersion phenomena in atmosphere, surface and subsurface area are outlined.
Titration of sodium chloride with silver nitrate in presence of sodium hydroxide
Home made silver sulphide ion selective electrode was prepared and applied for argentometric titration in alkaline media for the determination of thiamine hydrochloride.The amount of thiamine hydrochloride estimated from titration of ionisable chloride with silver nitrate was found to be 637 mg/g of the vitamin B 1 tablet. This result is in agreement with the value obtained from ion chromatographic (IC) and cyclic voltammetric (CV) techniques. In presence of chloride from other sources, these techniques fail, but thiamine in pharmaceutical preparation, however, can be determined by potentiometric titration in highly alkaline medium using silver- sulphide membrane electrode with silver nitrate solution at which there is no interference due to the presence of chloride from other sources. The results showed that home made silver- sulphide electrode can be used as an indicator electrode for the potentiometric determination of thiamine in pharmaceutical preparation. Keywords : Silver sulphide electrode; Potentiometric titration; Thiamine; Vitamin B 1 . DOI: 10.3126/sw.v8i8.3853 Scientific World Vol.8(8) 2010 pp.69-72
The aim of this study was carried out to assess heavy metals (Cu, Zn, Pb, Cd,) in soils as well as vegetables of respective place of the Bhakatpur District (Manohara, Nagadesh, Bode, Hanumanghat, Sipadol, Tathali and Gundu). The leafy vegetables under this study were Spinach, Cauliflower, Carrot, Cabbage and Broad leaf mustard. The results showed that the concentration of heavy metals in the plants and soils from the Bhakatpur was proportional in the order Zn> Cu>Pb> Cd. Spinach showed the extremely high accumulation tendency towards the heavy metals compare to other vegetables. The geo-accumulation class (Igeo) indicates that the agricultural soil of Hanumanghat, Manohara, Nagadesh and Bode are moderately contaminated of Cd.Scientific World, Vol. 12, No. 12, September 2014, page 48-55
The urban air pollution is a major environmental concern, particularly in the developing countries and in their major cities. In the present study an attempt has been made to assess the air pollution effect on micromorphological and biochemical parameters of Callistemon citrinus and Lagerstroemia indica. Biochemical parameters were analyzed by using standard protocol. one-way analysis of variance was performed with SPSS software, v. 20.0, and Duncan test (p ≤ 0.05) was used to compare averages of all measured biochemical parameters and micromorpholgical features. There was a decrease in number of stomata of both species at highly polluted site compared to less polluted site (control). Stomatal index of both species was found to be reduced in polluted site when compared to control. The number of clogged stomata was less in control area samples when compared to polluted sample. A number of epidermal cells were significantly decreased at heavily polluted site. Total chlorophyll content and leaf extract pH in both the plants were found to be significantly higher in control sites than in heavily polluted sites. Ascorbic acid, relative water content, and Air Pollution Tolerance Index (ATPI) was found to be significantly higher at more polluted plants than at control. Based on the present study results, Callistemon citrinus emerged as the most tolerant species with the highest APTI. Hence, Callistemon citrinus can be suggested for plantations along the roadside of urban areas for green belt development.
The bioconversion of tyrosine, dopamine, N- desacetylisoipecoside (15) and N- desacetylipecoside (16) into cephaeline (2), emetine (1), and psychotrine (3) into Alangium lamarckii Thw. (Alangiaceae) plant has been studied. Stereospecific incorporation of N- desacetylisoipecoside (15) into 1,2 and 3 has been demonstrated. Further it has been shown that reduction of C1’ – C2’ takes place after O-methylation of psychotrine (3). Feeding results further showed that cephaeline was poorly metabolized in the plants to form psychotrine (3) thus demonstrating that dehydrogenation of C1’ – C2’ does not take place. The efficient incorporation of cephaeline into emetine (1) further showed that O- methylation is the terminal step in the biosynthesis of emetine. Emetine (1) was poorly metabolized by the plants to form cephaeline (2) and psychotrine (3). The experiments thus demonstrated that dehydrogenation and O-demethylation of emetine (1) does not occur to give cephaeline (2) and psychotrine (3). Scientific World, Vol. 10, No. 10, July 2012 p24-28 DOI:
District representation of samples (indicated by black colour) studied for genetic variation at 15 STR loci in Nepalese population.  
Allele frequencies for the 15 STR loci in the AmpFlSTR® Identifiler® and statistical parameters were estimated from a sample of 233 unrelated individuals from different area of Nepal. A total of 161 alleles were found, with corresponding allelic frequencies ranging from 0.0021 to 0.4077. The MP, PD, PIC, PE, TPI, Ho and He ranged from 0.0282 to 0.1511, 0.8489 to 0.9717, 0.6478 to 0.8700, 0.4546 to 0.7631, 1.7651 to 4.3148, 0.7167 to 0.8841 and 0.7009 to 0.8833 respectively. Deviations from the Hardy–Weinberg Equilibrium were observed for D16S539, D18S51, D21S11 and TPOX Markers. One new allele has been detected in the process.
The laboratory tests were conducted to evaluate the allelopathic potential and phytochemical study of the four selected medicinal plants Ageratum conyzoides, Eclipta prostrata, Cannabis sativa and Woodfordia fructicosa. The aqueous extract bioassay of the plants with stem and root were conducted on the two test seeds Triticum aestivum (wheat) and Pisum sativum (pea) by filter paper method. Germination, seedling growth and biomass production were observed under the allelopathic study whereas under phytochemical study qualitative or presence or absence and quantitative or crude amount of the phytochemicals present were also estimated. For the allelopathic studies the germination and seedling growth of wheat and pea test species under the different concentrations 2 %, 4%, 6%, 8% and 10% of the stem and root extracts of the plants under study were carried out. Increased concentration of the aqueous extracts of the plants increased the inhibitory rate or decreased the germination and seedling growth.Species sensitivity varied with the test seeds and alkaloid, flavonoid, saponin, tannin, phenol, glycoside and essential oil were the phytochemicals present in the plant extracts.Scientific World, Vol. 12, No. 12, September 2014, page 56-61
Viable seeds of paddy and barnyard grass in different concentrations of aqueous extracts ( 2, 4, 6, 8 and 10 %) of leaf, stem and root of Chromolaena odorata were germinated at room temperatures. The leaf extract had strong inhibitory effect on seed germination as well as linear growth of paddy and barnyard grass. The order of inhibition was leaf >stem >root on both tested seeds. Allelopathic effect increased with increased concentration of the extracts. Key Words : Allelopathy; Paddy; Barnyard grass; Aqueous extract; Root length; Shoot length. DOI: 10.3126/sw.v8i8.3854 Scientific World Vol.8(8) 2010 pp.73-75
Directionally solidify optical microphotograph of U- ABT eutectic 
Excess thermodynamic Functions for eutectics s E (kJ mol -1 K -1 )
Phase diagram of binary organic system of urea (U) with 2-aminobenzothiazole (ABT) shows the formation of a eutectic at 0.350 mole fraction of urea. Growth kinetics of the eutectic and pure components studied by measuring the rate of movement of solid-liquid interface in a thin glass U-tube at different undercoolings (ÄT) suggests the applicability of HilligTurnbull’s equation: v = u (ÄT) n. The thermodynamic functions such as heat of mixing, entropy of fusion, roughness parameter, interfacial energy and excess thermodynamic functions were calculated from the enthalpy of fusion values, obtained from DSC data. The optical microphotographs of pure and eutectic alloy show their characteristic features. Scientific World, Vol. 10, No. 10, July 2012 p91-94 DOI:
There are a large number of binary liquid alloys the thermodynamic properties of mixing of which are not symmetrical about the equi-atomic composition-deviating maximally from those of the ideal alloys. Here we have considered three such alloys-indium-sodium, cadmium-sodium and copper-tin-and tried to calculate their heat of mixing at different concentrations of the ingredients. The liquidus lines of these alloys reveal that the constituent species form complexes. So, we have considered a quasi-lattice chemical model for computation of the thermodynamic entities. It is a statistical model in which grand partition function is used assuming that the energy of a given nearest neighbour bond is different if it belongs to the complex than if it does not. For each alloy we have started with the expression for excess free energy of mixing according to this model and computed the free energy of mixing for different concentrations of the metals within it by deriving the value of interaction parameters through successive approximation method. Thereafter, the expression for excess entropy of mixing is taken into account and the entropy of mixing is computed for different concentrations after finding out the temperature derivative of interaction parameters by the method of successive approximation. Finally the heat of mixing is calculated from these free energy of mixing and entropy of mixing on using the standard thermodynamic relation. The results explain the observed asymmetry in the heat of mixing of the said binary liquid alloys around equi-atomic composition. Key words : Binary liquid alloy; Quasi-lattice chemical model; Heat of mixing DOI: 10.3126/sw.v7i7.3836 Scientific World Vol.7(7) 2009 pp.96-99
The complex formation model is used to explain the anomalous behaviour of entropy of mixing of NaCd and AlMg liquid alloys as a function of concentration.The interionic pair potential evaluated within the framework of pseudopotential theory which in turn is used to obtain the values of hard-sphere diameter of NaCd and AlMg liquid alloys. The hard-sphere diameter is used to evaluate the concentration dependent anamoly in entropy of mixing which occurs due to preferential ordering of unlike atoms as nearest neighbour on NaCd and AlMg liquid alloys, which could be simultaneously understood with the help of complex formation model. The computed value of Entropy of mixing (S M ) from pseudopotential theory is positive at all concentration range except in NaCd liquid alloys. The disagreement between theory and experiment might be due to parameterisation of hard- sphere diameter of the complex ( ) and .
Changes in corrosion rates of the sputter-deposited amorphous W-xCr-yZr alloys including chromium and zirconium metals in 1 M NaOH solution open to air at 25?C, as a function of immersion time. Immersion Time / h  
Changes in the corrosion rates and open circuit potentials of the sputter?deposited ternary W?xCr?yZr alloys including tungsten, chromium and zirconium metals after immersion in 1 M NaOH open to air at 25?C, as a function of alloying zirconium content.  
Changes in corrosion rates of the sputter-deposited WxCr-yZr alloys including tungsten, chromium and zirconium metals in 1 M NaOH solution open to air at 25?C, as a function of alloy zirconium content. Alloy Zirconium Content / at %  
Changes in open circuit potentials for the sputter-deposited WxCr-yZr alloys including sputter-deposited tungsten, chromium and zirconium in 1 M NaOH solution at 25?C, as a function of immersion time.  
Simultaneous additions of tungsten, chromium and zirconium in the chromium- and zirconium-enriched sputter-deposited binary W-xCr and W-yZr are effective to improve the corrosion resistance property of the ternary amorphous W- xCr-yZr alloys after immersion for 240 h in 1 M NaOH solution open to air at 25°C. The corrosion rates of all the examined sputter-deposited (10-57)W-(18-42)Cr-(25-73)Zr alloys is higher than those of alloy-constituting elements (that is, tungsten, chromium and zirconium) in aggressive 1 M NaOH solution open to air at 25°C. The corrosion rates of all the examined sputter−deposited W–xCr–yZr alloys containing 10-57 at% tungsten, 18-42 at% chromium and 25-73 at% zirconium were in the range of 1.5-2.5 × 10 −3 mm/y or lower which are more than two orders of magnitude lower than that of sputter-deposited tungsten and even about one order of magnitude lower than those of the sputter-deposited zirconium in 1 M NaOH solution. Keywords : Ternary W–Cr–Zr alloys; Amorphous; Corrosion rate; Open circuit potential; 1 M NaOH. DOI: SW 2011; 9(9): 39-43
We report energetic of mixing behavior of liquid Al-Ga alloys, using simple statistical theory through concentration dependence thermodynamic, structural, transport and surface properties at 1023K. The concentration dependent thermodynamic functions (free energy of mixing, enthalpy of mixing, entropy of mixing and activity coefficient of the component), structural functions (concentration fluctuation in the long wavelength limit and chemical short range order parameter), transport properties (diffusivity and viscosity) and surface properties (surface segregation and surface tension) have got special attention to show a tendency of homo-coordination of atom in the mixture. The theoretical analysis reveals that input parameter, order energy is temperature dependent and Al-Ga alloys is of weakly interacting system.Scientific World, Vol. 12, No. 12, September 2014, page 14-20
In the present work we have considered the antimony-indium liquid alloy which shows anomaly as regards its heat of mixing and the concentration fluctuations in the long-wavelength limit. On the other hand, the free energy of mixing and the entropy of mixing are found to be symmetric about the equi-atomic composition. Such alloying behaviour has been tried to explain on the basis of conformal solution model. This is a statistical mechanical model based on the formation of complex within the liquid alloy. In this model besides the interaction between unlike atoms, that between each constituent element and the complex too is taken into account. In course of theoretical treatment the activity of antimony is also computed for different concentrations. Our results indicate that Sb-In alloys are thermodynamically most stable around the equi-atomic composition.
X-ray diffraction patterns of sputter-deposited ternary W- Cr-Ni alloys including binary W-15Ni alloy. 
The change in characteristic interatomic spacing of the sputter-deposited ternary W-Cr-Ni alloys as a function of alloy chromium content. The interatomic spacing of the tungsten, chromium and nickel metals are also shown for comparison. 
Composition-structure diagram of sputter-deposited W-Cr- Ni alloys. 
Corrosion rates of sputter-deposited W-Cr-Ni alloys including those of sputter-deposited tungsten, chromium and nickel in 12 M HCl at 30 o C, open to air. 
Potentiodynamic anodic and cathodic polarization curves for sputter-deposited W-Cr-Ni alloys measured after immersion for 1 h in 12 M HCl solution at 30 o C, open to air. The polarization curves for sputtered tungsten, chromium and nickel metals are also shown for 
The passivity of sputter-deposited ternary W-Cr-Ni alloys is investigated by immersion tests and electrochemical measurements in 12 M HCl solution at 30°C, open to air. Particular attention is paid to the effects of alloying elements to the corrosion behavior. All the examined amorphous or/and nanocrystalline W-Cr-Ni alloys are passivated spontaneously even in an aggressive environment of 12 M HCl, and hence these alloys showed higher corrosion resistance than those of alloyconstituting elements. The chromium addition suppresses the anodic dissolution current because of the formation of tetravalent chromium oxyhydroxide having a relatively high activity for both cathodic oxygen and hydrogen reduction with a consequent ennoblement of the open circuit potential. The ennoblement of the open circuit potential leads to the formation of the passive chromium oxyhydroxide film. It is, therefore, considered that the addition of chromium improves synergistically the corrosion resistance and passivating abilities of the sputter-deposited binary W-Ni alloys in 12 M HCl solution. Keywords: Sputter-deposition; Ternary W-Cr-Ni alloys; Corrosion-resistant; Electrochemical measurements. DOI: 10.3126/sw.v7i7.3819 Scientific World Vol.7(7) 2009 pp.24-28
In the present work we have considered two molten amalgams e.g. sodium amalgam and potassium amalgam. Efforts are made to compute the activity of mercury therein by applying Flory's model. This statistical mechanical model is based on the size factor of the ingredients of a binary liquid alloy. In case of each of the amalgams we have started with the expression for the free energy of mixing (GM) according to this model. After knowing the ratio of the atomic volumes of the constituent species of an amalgam the prime task becomes the determination of the interchange energy (ω) between them. For this purpose the experimental values of GM for different concentrations of the ingredients of the amalgam are collected. From these known values ω has been computed by using the expression for GM. A suitable value of ω is chosen from the set of values so obtained. Putting this value of ω the free energy of mixing is calculated for several concentrations and then compared with its observed values. Accordingly, a modified value of ω has been considered and the calculations are repeated. In this way by the method of successive approximations we have ascertained the value of the interchange energy. Thereafter, with the help of standard thermodynamic relation activity has been computed. The results explain the observed anomaly of the activity of mercury in the present molten amalgams. Keywords: Binary liquid alloys; Flory's model; Amalgams; Activity of mercury. DOI: 10.3126/sw.v8i8.3850 Scientific World Vol.8(8) 2010 pp.56-58
Scientific World, Vol. 11, No. 11, July 2013, page 113-120 DOI:
Amelogenin is the well-liked process for sex typing in recent days. Exceptional failures to amplify AMELY accurate products can cause erroneous gender identification consequence male samples mistakenly identified as females. A total of 9 null AMELY males were noticed in 200 males of 72 Nepalese surnames by means of 4.5% frequency. No amplification of DYS458 Marker in all null AMELY males but great sharing of amplified Y STR alleles among them is a probable sign of the general phylogenetic origin. Key words: Forensic; Gender determination; Amelogenin; Null AMELY; Y-STR haplotypes etc. DOI: 10.3126/sw.v8i8.3858 Scientific World Vol.8(8) 2010 pp.97-101
Numerical methods form an important part of the pricing of financial derivatives where there is no closed form analytical formula. Black-Scholes equation is a well known partial differential equation in financial mathematics. In this paper, we have studied the numerical solutions of the Black-Scholes equation for European options (Call and Put) as well as American options with dividends. We have used different approximate to discretize the partial differential equation in space and explicit (Forward Euler’s), fully implicit with projected Successive Over-Relaxation (SOR) algorithm and Crank-Nicolson scheme for time stepping. We have implemented and tested the methods in MATLAB. Finally, some numerical results have been presented and the effects of dividend payments on option pricing have also been considered.
Fate of microorganisms with digestion time and temperature Scientific World, Vol. 8, No. 8, July 2010 48 
Anaerobic digestion is a technique used for the sanitizing the sewage sludge before its final disposal. We determined the fate of indicators and pathogens in sewage sludge mixture subjected to mesophilic anaerobic digestion (MAD) and ambient anaerobic digestion (AAD) for 30 and 35 days respectively by culture based microbiological methods (bacteria) and formal-ether sedimentation technique (parasites). While monitoring the organisms at five days intervals, MAD effectively reduced most of the bacteria and parasites to undetectable levels than AAD. Interestingly, the highest reductions in load were observed for faecal coliforms (5.16 log 10 cfu/ml) in the sewage sludge mixture of MAD which met the class A biosolid standard (USEPA). Like wise, the bacterial load reductions were negatively correlated and statistically significant (p< 0.005) with days of both digestions and the relation between total coliforms load and days of MAD experienced higher correlation coefficient (r= -0.992) and R 2 (0.984) values which shows higher validity in regression model. Therefore, MAD can be considered as a promising method for reduction of indicator and pathogenic microorganisms in sewage sludge mixture. Keywords: Anaerobic digestion; Correlation coefficient; Regression model; Sewage sludge. DOI: 10.3126/sw.v8i8.3848 Scientific World Vol.8(8) 2010 pp.47-50
A research work of antagonistic effect of water solvent and organic solvent (Ethanol of different concentration 50 % and 100 %) of extracts of Lantana camara were studied against with pathogenic fifteen strains of bacteria. Among fifteen species, of bacteria most of them were inhibited by L.camara extracts and only two species such as Klebsella oxytoca and Klebsella pneumoniae did not showed antibacterial activity with same extract with same concentration. Extracts obtained from the organic solvent and water solvent showed the different antagonistic properties with the same bacterial strains. Those bacterial strains which were inhibited their growth by water solvent could not inhibited by organic solvent extracts. This depends on presence of polar and non-polar bioactive compounds in the extracts. It also depends on polar and non-polar solvents used for the plant extract. Organic solvent extracts showed antibacterial effect towards Pseudomonas aeruginosa, Staphylococcus sp., Bacillus cereus , Bacillus subtilis, Bacillus thurengiensis , Escherichia coli , Staphylococcus aureus , Proteus mirabilis and water solvent extracts showed antibacterial effect towards Pseudomonas aeruginosa , Staphylococcus sp. , Citrobacter frundi , Proteus sp., Bacillus subtilis , Enterobacter aerogenes , Salmonella paratyphie , Staphylococcus aureus , Shigella dysenteria. Both solvent extracts showed high antibacterial effect towards Staph aureus, Staphylococcus sp. and Pseudomonas aeruginosa. Both plant extracts showed selective antibacterial effect with different strains of bacteria, which shows that these are confined to cure the same bacterial diseases. Key words: Lantana camara ; Pathogenic bacteria; Antimicrobial; Organic and water solvent; Concentration. DOI: 10.3126/sw.v7i7.3828 Scientific World Vol.7(7) 2009 pp.64-67
Top-cited authors
Tista Prasai Joshi
  • Nepal Academy of Science and Technology
Bharat Babu Shrestha
  • Tribhuvan University
Sanjay Kumar Jha
  • Tribhuvan University
Dev Raj Joshi
  • Tribhuvan University
Seerjana Maharjan
  • Tribhuvan University