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16 result(s) for "Belwal, K"
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Nanosilica-supported liposome (protocells) as a drug vehicle for cancer therapy
This study encompasses the development and comparison of nanosilica-supported liposome (protocells), conventional liposome, and polyethylene glycol (PEG)-liposome. An effort was made to study the drug encapsulation efficiency and the in vitro release of the drug, and whether protocells (nanovesicles) could sustain the release of the drug by increasing the residence time, which could reduce the dose-related systemic toxicity of the drug, that is, vincristine sulfate. Nanovesicles had a good encapsulation efficiency (71%), which was comparable to the conventional and PEG-liposome, which were 74% and 78%, respectively. The obtained vesicles were in the size range 100-150 nm, and the drug release efficiency of conventional, PEGylated, and protocells liposome was about 67%, 42%, and 52%, respectively, in 150 minutes. The intermediate value of nanosilica-supported liposome indicates the ability for stable and controlled release of the drug, which prevents the rapid burst or slower release of the drug. This study reveals that protocells as nanovesicles could be a better choice for the delivery of cancer drugs such as vincristine sulfate.
Potential of herbarium records to sequence phenological pattern: a case study of Aconitum heterophyllum in the Himalaya
Several pieces of evidence indicate that global climate change is affecting biological systems all across the world. Phenology is one of the tools that may indicate changing patterns. The paper focuses on the phenological pattern of alpine/sub-alpine species Aconitum heterophyllum , a high-value medicinal herb of the Indian Himalayan Region (IHR), a global hotspot and known to be sensitive to climatic change. In all 117 herbarium specimens of the species collected from three provinces (Western Himalaya, North West Himalaya and Trans Himalaya) of the region were recorded. Historic herbarium records (1848–2003) were analyzed to predict the flowering patterns using Generalized Additive Model (GAM) in view of complexity in the herbarium-based data structure. GAM indicated that the flowering time responded significantly, 26 days earlier per 1,000 m ( P  < 0.02). Likewise, the model showed significantly earlier flowering (17–25 days) during the last 100 years ( P  < 0.01). Moreover, maximum temperature of winter (December–February) explained increasing trends at both elevations (lower and mid) and mean winter temperature influenced the early flowering time (19–27 days) with an increase of 1°C. The overall early flowering of A. heterophyllum may perhaps be considered as indicator of climate change; however, more datasets of herbarium records are required to further strengthen this premise. This study was undertaken to show that herbarium records could be utilized as a potential resource for assessing climate change using GAM.
Statistical investigation through stratified random sampling for apple production in Himachal Pradesh
The present study focuses on standardization of sampling technique and comparison of different types of sample allocation methods in combination with various stratification tools (optimum strata boundaries, number of strata and optimum sample size etc.) for obtaining efficient estimators of area and production of apple in Himachal Pradesh. Forth is purpose, various aspects involved in optimum stratification with reference todata collected from the selected or chardists in district Shimla, during the year 2011-12 have been analyzed. The variable \"Area under Apple\" was chosen as the stratification variable as it had high correlation(r=0.96) with the estimation variable \"Production of Apple\". Four methods of construction of strata viz., equalization of strata total, equalization of cumulative of ?f(y) , equalization of cumulative of ½r(y)+f(y) and equalization of cumulative of were used and their relative efficiencies for estimating total production of apple in the study district of the state have been analyzed. The critical examination of the result revealed that with the increase in number of strata from 2 to 4 and sample size from 10 to 40, equalization of cumulative of method along with Neyman allocation resulted in least variance (0.89) and maximum percentage gain in efficiency (20418.16). Thus, equalization of cumulative of method with L>2 can profitably be applied for the estimation of apple production in the study district of the state Himachal Pradesh, India.
Genetic divergence evaluation of apple germplasm by D2 multivariate analysis
Genetic divergence was worked out in the new germplasm of apple (Malus × domestica Borkh.) including 42 genotypes. Mahalanobis's D2 statistics was applied for identifying the potential parents to be involved in the hybridization programme for trait specific improvement or selecting better segregants. On the basis of performance for various traits, genotypes were grouped into three clusters and maximum numbers of genotypes i.e. 28 were accommodated in cluster I , while 10 and 4 genotypes were arranged in cluster II and III respectively. The average intra cluster distance was maximum in cluster II (2.214) and minimum in cluster III (1.212). Inter cluster distance was maximum between cluster II and III (5.077) indicating that hybridization between genotypes from cluster II and III can be utilized for getting the superior recombinants in segregating generations. On the basis of cluster means for various characters , cluster II was found superior for shoot thickness (0.34cm), inter - nodal length (2.38cm), number of lenticels (62.10) and leaf blade length (8.79cm) whereas cluster III was found superior for leaf blade width (5.10cm), petiole length (2.64cm) and leaf blade ratio (3.62). Hence, hybridization between parents from cluster II and cluster III for these characters can produce better recombinants in segregating generations.
Time-Series Photometric Detection and Physical Characterization of Variable Stars in Four Intermediate- to Old-Age Galactic Open Clusters
We present a ground-based time-series photometric study of stellar variability in four intermediate- to old-age open clusters NGC 2192, NGC 2266, NGC 2509, and IC 1369 based on high-cadence Cousins R-band observations obtained with the 0.6 m VASISTHA telescope at the IERCOO observatory. The monitoring campaign comprises more than 34 h of time-series data, providing sensitivity to short-period variability on timescales of 0.02-2 d. We identified between 190 and 290 probable members in each cluster using a Gaussian Mixture Model. Structural parameters were derived from radial density profiles fitted with King models. Fundamental parameters were further constrained using color-magnitude diagram analysis with PARSEC isochrones, yielding ages of 0.3-1.6 Gyr and distances of 2.5-3.9 kpc. From the time-series photometry, we identify four new variable stars and seven previously uncharacterized periodic variables, including {\\delta} Scuti and {\\gamma} Doradus pulsators, as well as rotational variables. The detected variables exhibit periods between 0.12-0.90 d, with R-band amplitudes ranging from 0.01 to 0.20 mag. Periods were determined using Lomb-Scargle analysis of calibrated light curves. For a subset of variables, spectral energy distribution fitting was performed to derive effective temperatures (4300-10 000 K), radii (1.3-46 R_{\\odot}), and luminosities (2-100 L_{\\odot}), enabling reliable placement on the Hertzsprung-Russell diagram. We present PHOEBE light-curve modelling of the W UMa-type eclipsing binary Gaia DR3 2164531610149292288 in IC 1369, deriving its physical parameters and providing the first detailed characterization beyond its previously reported variability. These results demonstrate that combining dense-cadence ground-based observations with Gaia astrometry provides a reliable approach for identifying and characterizing variable stars in OCs.
A Spectrophotometric analysis and dust properties of classical nova V5584 Sgr
In this work, optical observations of the nova V5584 Sgr are presented. These observations cover different phases including pre-maximum, early decline, and nebular. The spectra are dominated by hydrogen Balmer, Fe II, and O I lines with P-Cygni profiles in the early phase, which are subsequently observed in complete emission. The presence of numerous Fe II lines and low ejecta velocity aligns with the Fe II type nova classification. From optical and NIR colors it is clear that this nova manifests dust formation in the ejecta. The dust temperature and mass were estimated from a spectral energy distribution (SED) fit to the JHK band magnitudes and the WISE data. Light curve analysis shows t\\(_2\\) and t\\(_3\\) values of \\(\\) 26 and \\(\\) 48 days, classifying the nova as moderately fast. The physical and chemical properties during early decline and later phases were evaluated using the photoionization code CLOUDY. The best-fit model parameters from two epochs of multiwavelength spectra are compatible with a hot white dwarf source with a roughly constant luminosity of \\(\\) (2.08 \\(\\) 0.10) \\(\\) 10\\(^36\\) erg s\\(^-1\\). We find an ejected mass of \\(\\) (1.59 \\(\\) 0.04) \\(\\) 10\\(^-4\\)M\\(_\\). Abundance analysis indicates that the ejecta is significantly enriched relative to solar values, with O/H = 30.2, C/H = 10.8, He/H = 1.8, Mg/H = 1.68, Na/H = 1.55, and N/H = 45.5 in the early decline phase, and O/H = 4.5, Ne/H = 1.5, and N/H = 24.5 in the nebular phase.
The Unexplored Dusty Nova LMCN 2009-05a in the Large Magellanic Cloud
We present a detailed spectrophotometric study of nova LMCN 2009-05a, located in the Large Magellanic Cloud (LMC). Photometric observations reveal a dust dip in the optical light curve, classifying it as a D-class nova. Light curve analysis yields t2 and t3 decline times of approximately 46 and 80 days, respectively, placing the nova in the category of moderately fast novae. Spectroscopic observations cover multiple phases, including pre-maximum, early decline, and nebular. The spectra are initially dominated by hydrogen Balmer and Fe II lines with P-Cygni profiles, which later transition into pure emission. During the optical minimum, a discrete absorption feature was observed in the H{\\alpha} and [O I] line profiles. The physical and chemical properties during the early decline and nebular phases were analyzed using the photoionization code CLOUDY. Dust temperature, mass, and grain size were estimated through spectral energy distribution (SED) fitting to the WISE data. On day 395 post-outburst, we estimate the dust temperature to be approximately 700 K. Additionally, we examined the correlation between dust condensation time (tcond ) and t2 for LMC novae, finding a trend consistent with previous studies of Galactic novae.
Multiwavelength Study of Blue Straggler Stars in Tombaugh 2: Evidence for Binary Mass Transfer and Constraints on Cluster Dynamical State
We present a focused multiwavelength study of blue straggler stars (BSSs) in the intermediate-age open cluster Tombaugh 2, located in the outer Galactic disk, to constrain the dominant formation pathways of BSSs in a low-density environment. Cluster members are identified using Gaia DR3 astrometry through a Gaussian Mixture Model, yielding a clean sample of high-probability members. Color-magnitude diagram analysis indicates an age of 1.74 Gyr. The radial surface density profile is well described by a King model, indicating a centrally concentrated overall structure, while the cluster exhibits only weak or no clear evidence of mass segregation among its stellar populations. We identify 26 BSS candidates and 2 YSS candidates. Spectral energy distributions constructed from ultraviolet, optical, and infrared photometry reveal that 9 BSSs (32%) exhibit significant ultraviolet excess, indicating an additional hot component. Binary SED decomposition identifies stripped companions with effective temperatures Teff \\(\\) (1.5-8) \\(\\) 10\\(^4\\) K and radii R \\(\\) 0.04-0.28 R_\\(\\), consistent with proto-white dwarfs, extremely low-mass pre-helium white dwarfs, and young hot remnants formed through recent mass transfer. A slight central concentration of BSSs, together with stripped companions, suggests that binary mass transfer is an important formation channel, with no evidence for merger-driven formation. Multi-epoch VLT/FLAMES spectroscopy reveals radial-velocity variability in several systems, providing independent evidence for binarity. Our results highlight that optical-infrared photometric analyses alone may fail to detect hot compact companions, while spectroscopy and ultraviolet observations provide complementary constraints, with ultraviolet data offering a direct probe of such companions in intermediate-age open clusters.
Dynamical and Photometric Analysis of NGC 146 and King 14: Evidence for a Co-Moving, Unbound Cluster Pair
To understand the nature of the NGC 146-King 14 cluster pair, we conducted a detailed photometric, astrometric, and dynamical study using multiwavelength data from Gaia DR3, Pan-STARRS1, WISE, and TESS. Using a probabilistic approach, we identified 770 and 690 high-probability members of NGC 146 and King 14, respectively. Both clusters exhibit well-defined radial density profiles consistent with King models. We estimate the cluster ages as 20 \\(\\pm\\) 5 Myr and 50 \\(\\pm\\) 10 Myr from isochrone fitting, and distances of 2.98 \\(\\pm\\) 0.33 kpc and 2.51 \\(\\pm\\) 0.23 kpc from parallaxes after applying the Bailer-Jones criteria. The clusters show consistent mean proper motions. The mass function slopes (1.51 \\(\\pm\\) 0.18 and 1.50 \\(\\pm\\) 0.15) are close to the Salpeter value, and the extinction follows a normal Galactic reddening law (RV ~ 3.1). Three-dimensional mapping gives a projected separation of ~ 9 pc. Orbit integration using the galpy MWPotential2014 model shows that NGC 146 and King 14 move in nearly circular, disk-like orbits with similar mean orbital radii (Rm ~ 9 kpc) and orbital periods of roughly 255 Myr. A dynamical separation of ~ 32 pc indicates that both clusters share a common spatial and kinematic association, consistent with a co-moving pair. However, their relative velocity exceeds the escape velocity set by their combined mass, indicating they are not gravitationally bound. TESS light curves reveal seven variable stars, including \\(\\gamma\\) Doradus, SPB stars, and eclipsing binaries, though only one is a likely member. Overall, the clusters likely formed within the same giant molecular cloud and now exist as an unbound co-moving pair.
The Dusty Aftermath of a Rapid Nova: V5579 Sgr
V5579 Sgr was a fast nova discovered in 2008 April 18.784 UT. We present the optical spectroscopic observations of the nova observed from the Castanet Tolosan, SMARTS and CTIO observatories spanning over 2008 April 23 to 2015 May 11. The spectra are dominated by hydrogen Balmer, Fe II and O I lines with P-Cygni profiles in the early phase, typical of an Fe II class nova. The spectra show He I and He II lines along with forbidden lines from N, Ar, S, and O in the nebular phase. The nova showed a pronounced dust formation episode that began about 20 days after the outburst. The dust temperature and mass were estimated using the WISE data from spectral energy distribution (SED) fits. The PAH-like features are also seen in the nova ejecta in the mid-IR Gemini spectra taken 522 d after the discovery. Analysis of the light curve indicates values of t\\(_2\\) and t\\(_3\\) about 9 and 13 days, respectively, placing the nova in the category of fast nova. The best fit cloudy model of the early decline phase JHK spectra obtained on 2008 May 3 and the nebular optical spectrum obtained on 2011 June 2 shows a hot white dwarf source with T\\(_{BB}\\) \\(\\sim\\) 2.6 \\(\\times\\) 10\\(^5\\) K having a luminosity of 9.8 \\(\\times\\) 10\\(^{36}\\) ergs s\\(^{-1}\\). Our abundance analysis shows that the ejecta is significantly enhanced relative to solar, O/H = 32.2, C/H = 15.5 and N/H = 40.0 in the early decline phase and O/H = 5.8, He/H = 1.5 and N/H = 22.0 in the nebular phase.