المؤلفون: Ram Kaka, Prakash Jyoti, Kumari Kultaran, Kumar Pankaj

المصدر: Studia Geotechnica et Mechanica, Vol 44, Iss 2, Pp 114-122 (2022)

مصطلحات موضوعية: linear stability, ferrofluid, oscillatory motions, ferrothermohaline convection, Engineering geology. Rock mechanics. Soil mechanics. Underground construction, TA703-712

الوصف: It is proved analytically that the complex growth rate σ= σr+iσi (σr and σi are the real and imaginary parts of σ, respectively) of an arbitrary oscillatory motion of neutral or growing amplitude in ferrothermohaline convection in a ferrofluid layer for the case of free boundaries is located inside a semicircle in the right half of the σrσi-plane, whose center is at the origin and radius = Rs[1−M1′(1−1M5)]Pr′,{\rm{radius}}\, = \,\sqrt {{{{R_s}\left[{1 - M_1^{'}\left({1 - {1 \over {{M_5}}}} \right)} \right]} \over {P_r^{'}}}}, where Rs is the concentration Rayleigh number, Pr′ is the solutal Prandtl number, M1′ is the ratio of magnetic flux due to concentration fluctuation to the gravitational force, and M5 is the ratio of concentration effect on magnetic field to pyromagnetic coefficient. Further, bounds for the case of rigid boundaries are also derived separately.

وصف الملف: electronic resource

العلاقة: https://doaj.org/toc/2083-831XTest

الوصول الحر: https://doaj.org/article/7fbfd78119a4405db67ac68cf0f58da7Test

المؤلفون: Sonika, Gangwar, Sunil, Kumar, Pankaj, Taraphder, A., Yadav, C. S.

مصطلحات موضوعية: Condensed Matter - Strongly Correlated Electrons, Condensed Matter - Materials Science

الوصف: 1T-VSe$_2$ is a narrow band transition metal chalcogenide that shows charge density wave (CDW) state below $T_{CDW}$ = 110 K. Here, we have explored the relevance of Kohler's rule and the thermal transport properties of VSe$_2$ across the CDW state. The magnetoresistance (MR) follows Kohler's rule above $T_{CDW}$, while an extended Kohler's rule is employed below $T_{CDW}$. Interestingly, we observed an anomaly in MR at T = 20 K, below which MR value decreases on lowering temperature. This anomaly is also reflected in the slope ($\kappa$) of Kohler's plots and the relative change in the thermal excitation induced carrier density ($n_T$) also. The $T_{CDW}$ remains largely unaffected in both electrical resistivity ($\rho(T)$) and longitudinal Seebeck coefficient ($\it{S_{xx}}$) even under a strong magnetic field of 14 Tesla. However, the application of magnetic field enhances the peak intensity of $\it{S_{xx}}$ at T $\sim$ 60 K. Additionally, $\it{S_{xx}(T)}$ curves measured at different fields exhibit a crossover at T = 20 K, which suggest the existence of unique feature in the CDW state of VSe$_2$ \textit{i.e.} a locally exact isosbestic point.
Comment: 10 pages, 5 figures

الوصول الحر: http://arxiv.org/abs/2405.15483Test

المؤلفون: Kayshap, Pradeep, Karpen, Judith T., Kumar, Pankaj

مصطلحات موضوعية: Astrophysics - Solar and Stellar Astrophysics

الوصف: We analysed Interface-Region Imaging Spectrograph (IRIS) and the Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA) observations of a small coronal jet that occurred at the solar west limb on 2014 August 29. The jet source region, a small bright point, was located at an active-region periphery and contains a fan-spine topology with a mini-filament. Our analysis has identified key features and timings that motivate the following interpretation of this event. As the stressed core flux rises, a current sheet forms beneath it; the ensuing reconnection forms a flux rope above a flare arcade. When the rising filament-carrying flux rope reaches the stressed null, it triggers a jet via explosive interchange (breakout) reconnection. During the flux-rope interaction with the external magnetic field, we observed brightening above the filament and within the dome, along with a growing flare arcade. EUV images reveal quasi-periodic ejections throughout the jet duration with a dominant period of 4 minutes, similar to coronal jetlets and larger jets. We conclude that these observations are consistent with the magnetic breakout model for coronal jets.
Comment: 21 pages, 09 Figures, Accepted for Publication in Solar Physics

الوصول الحر: http://arxiv.org/abs/2405.04766Test

المؤلفون: Kumar Kamlesh, Kumar Pankaj

المصدر: E3S Web of Conferences, Vol 405, p 03018 (2023)

مصطلحات موضوعية: recycled aggregate concrete (rac), durability, mineral admixtures, compressive strength, natural aggregate concrete (nac), Environmental sciences, GE1-350

الوصف: This research provides insight of experimental study on performance of concrete produced from natural and recycled aggregates. The strength of recycled aggregate concrete and its durability is still questionable as compared to the concrete with natural aggregates. The intention of this research was to assess the longevity and durability of concrete specimens composed of both conventional and recycled aggregates. This experiment involved preparing concrete specimens with recycled aggregate at 0%, 50% and 100% using a M25 mix design. The physical and mechanical characteristics of the concrete specimens such as compressive test, UPV test and split tensile strength test were assessed over a period of 28 days. The water absorption is very crucial as it can lead to concrete degradation and reduced durability over time. The results of this study indicate that strength of concrete using recycled aggregates along with silica fume and metakaolin shows enhanced mechanical properties. Therefore, recycled aggregates may be a viable and ecologically acceptable and substitute to natural aggregates in the preparation of concrete.

وصف الملف: electronic resource

العلاقة: https://www.e3s-conferences.org/articles/e3sconf/pdf/2023/42/e3sconf_icstce2023_03018.pdfTest; https://doaj.org/toc/2267-1242Test

الوصول الحر: https://doaj.org/article/208da1031ea24696a77242816fec963bTest

المؤلفون: Kumar, Pankaj, Nakariakov, Valery M., Karpen, Judith T., Cho, Kyung-Suk

مصطلحات موضوعية: Astrophysics - Solar and Stellar Astrophysics

الوصف: Mutual conversion of various kinds of magnetohydrodynamic (MHD) waves can have profound impacts on wave propagation, energy transfer, and heating of the solar chromosphere and corona. Mode conversion occurs when an MHD wave travels through a region where the Alfv\'en and sound speeds are equal (e.g., a 3D magnetic null point). Here we report the first EUV imaging of mode conversion from a fast-mode to a slow-mode MHD wave near a 3D null point using Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA) observations. An incident fast EUV wavefront associated with an adjacent eruptive flare propagates laterally through a neighboring pseudostreamer. Shortly after the passage of the fast EUV wave through the null point, a slow-mode wave appears near the null that propagates upward along the open structures and simultaneously downward along the separatrix encompassing the fan loops of the pseudostreamer base. These observations suggest the existence of mode conversion near 3D nulls in the solar corona, as predicted by theory and MHD simulations. Moreover, we observe decaying transverse oscillations in both the open and closed structures of the pseudostreamer, along with quasiperiodic type III radio bursts indicative of repetitive episodes of electron acceleration.
Comment: Nature Communications (published), 12 pages, 8 Figures

الوصول الحر: http://arxiv.org/abs/2403.02250Test

المؤلفون: Pawłowski, Jarosław, Kumar, Pankaj, Watanabe, Kenji, Taniguchi, Takashi, Novoselov, Konstantin S., Churchill, Hugh O. H., Kotekar-Patil, Dharmraj

مصطلحات موضوعية: Condensed Matter - Mesoscale and Nanoscale Physics

الوصف: Spin-valley properties in two-dimensional (2D) semiconducting transition metal dichalcogenides (TMDC) has attracted significant interest due to the possible applications in quantum computing. Spin-valley properties can be exploited in TMDC quantum dot (QD) with well-resolved energy levels. This requires smaller QDs, especially in material systems with heavy carrier effective mass e.g. TMDCs and silicon. Device architectures employed for TMDC QDs so far have difficulty achieving smaller QDs. Therefore, an alternative approach in the device architecture is needed. Here, we propose a multilayer device architecture to achieve a gate-defined QD in TMDC with a relatively large energy splitting on the QD. We provide a range of device dimensions and dielectric thicknesses and its correlation with the QD energy splitting. The device architecture is modeled realistically. Moreover, we show that all the device parameters used in modeling are experimentally achievable. These studies lay the foundation for future work toward spin-valley qubits in TMDCs. The successful implementation of these device architectures will drive the technological development of 2D materials-based quantum technologies.
Comment: main text: 20 pages, 5 figures; supplementary: 9 pages, 7 figures

الوصول الحر: http://arxiv.org/abs/2402.19480Test

المؤلفون: Kumar Pankaj Yaswant, Jagadale Vasantrao Mahesh, Prakash Nilmani, Kumar Jat Raj, Kumar Rajesh, Kumar Vinay, Kumar Pankaj

المصدر: Open Agriculture, Vol 4, Iss 1, Pp 41-51 (2019)

مصطلحات موضوعية: pic, gfd, tgw, gcv, pcv, Agriculture, Agriculture (General), S1-972

الوصف: The current study focuses and emphasis on the potential of heat stress to negatively affect crop physiology. Here, we have screened 19 wheat (Triticum aestivum L.) genotypes for their tolerance of heat stress. Significant differences were observed among the genotypes for all the traits under consideration. Exploitable extent of genetic variability amongst the entries was present as revealed by considerably higher estimates of mean %. On the basis of Heat susceptibility Index, Halna, Mon’s Ald’s, genotypes Cuo/79/Prulla and K 307 were identified as heat-tolerant whereas SAWSN 3041, SAWSN 3101 and K 0583 were identified as heat-susceptible. The 17 wheat microsatellite markers were capable of detecting 89 alleles with an average of 4.6 alleles per locus. Polymorphism Information Content value ranged from 0.16 for the primer XGWM 516 to 0.83 for DUPW 117 with an average of 0.60. A perusal of similarity coefficients clearly reflected that a very high degree of similarity exists between wheat variety Mon’s Ald’s and SAWSN 3101 (0.70). On the other hand, the two most distantly related cultivars were found to be AKAW 4008 and PBW 343 (0.034). BARC 4, BARC 170, BARC 311, PSP 3058, WHE014.H04 and GWM 458 were strongly associated with the heat tolerance for traits TGW and BARC 311 was strongly associated with terminal heat tolerance for number of grains/plant respectively. Considering all the parameters it is adjudged that relatively stable genotypes may be evaluated at various agro climatic regions for grain yield and heat tolerance along with other contributing characters and ideal plant type.

وصف الملف: electronic resource

العلاقة: https://doaj.org/toc/2391-9531Test

الوصول الحر: https://doaj.org/article/eec372056cd049808ea6c18bf2187f1eTest

المؤلفون: Kumar, Pankaj, Eriksson, Martin, Kharytonau, Dzmitry S., You, Shujie, Natile, Marta Maria, Vomiero, Alberto

المصدر: ACS Applied Energy Materials. 7(4):1421-1432

مصطلحات موضوعية: antimony sulfide solar cells, average visible transmittance, copper(I) thiocyanate, hole transport layer, hydrothermal deposition, semitransparent solar cells, thin film solar cells, Experimentell fysik, Experimental Physics

الوصف: Published by American Chemical Society.An inorganic wide-bandgap hole transport layer (HTL), copper(I) thiocyanate (CuSCN), is employed in inorganic planar hydrothermally deposited Sb2S3 solar cells. With excellent hole transport properties and uniform compact morphology, the solution-processed CuSCN layer suppresses the leakage current and improves charge selectivity in an n-i-p-type solar cell structure. The device without the HTL (FTO/CdS/Sb2S3/Au) delivers a modest power conversion efficiency (PCE) of 1.54%, which increases to 2.46% with the introduction of CuSCN (FTO/CdS/Sb2S3/CuSCN/Au). This PCE is a significant improvement compared with the previous reports of planar Sb2S3 solar cells employing CuSCN. CuSCN is therefore a promising alternative to expensive and inherently unstable organic HTLs. In addition, CuSCN makes an excellent optically transparent (with average transmittance >90% in the visible region) and shunt-blocking HTL layer in pinhole-prone ultrathin(<100 nm) semitransparent absorber layers grown by green and facile hydrothermal deposition. A semitransparent device is fabricated using an ultrathin Au layer (∼10 nm) with a PCE of 2.13% and an average visible transmittance of 13.7%.

وصف الملف: electronic

الوصول الحر: https://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-104466Test
https://doi.org/10.1021/acsaem.3c02492Test
https://ltu.diva-portal.org/smash/get/diva2:1842829/FULLTEXT01.pdfTest

المؤلفون: Kumar, Pankaj, Vogel, Heike, Bruckert, Julia, Muth, Lisa Janina, Hoshyaripour, Gholam Ali

المصدر: npj Climate and Atmospheric Science 7, 110 (2024)

مصطلحات موضوعية: Physics - Atmospheric and Oceanic Physics, Physics - Applied Physics, Physics - Computational Physics, Physics - Optics

الوصف: Aerosols influence weather and climate by interacting with radiation through absorption and scattering. These effects heavily rely on the optical properties of aerosols, which are mainly governed by attributes such as morphology, size distribution, and chemical composition. These attributes undergo continuous changes due to chemical reactions and aerosol micro-physics, resulting in significant spatio-temporal variations. Most atmospheric models struggle to incorporate this variability because they use pre-calculated tables to handle aerosol optics. This offline approach often leads to substantial errors in estimating the radiative impacts of aerosols alongwith posing significant computational burdens. To address this challenge, we introduce a novel and computationally efficient machine learning ap proach called MieAI. It allows for online calculation of the optical properties of internally mixed aerosols with a log-normal size distribution. Importantly, MieAI fully incorporates the variability in aerosol chemistry and microphysics. Our evaluation of MieAI against traditional Mie calculations, using number concentrations from ICOsahedral Nonhydrostatic model with Aerosol and Reactive Trace gases (ICON-ART) simulations, demonstrates that MieAI exhibits excellent predictive accuracy for aerosol optical properties. MieAI achieves this with errors well within 10%, and it operates more than 1000 times faster than the benchmark approach of Mie calculations. Due to its generalized nature, the MieAI approach can be implemented in any chemistry transport model which represents aerosol size distribution in the form of log-normally distributed internally mixed modes. This advancement has the potential to replace frequently employed lookup tables and play a substantial role in the ongoing attempts to reduce uncertainties in estimating aerosol radiative forcing.
Comment: 26 pages, 7 main and 8 appendix figures, 3 main and 3 appendix tables

الوصول الحر: http://arxiv.org/abs/2312.06497Test

المؤلفون: Monangi, Nagendra, Xu, Huan, Fan, Yue-Mei, Khanam, Rasheeda, Khan, Waqasuddin, Deb, Saikat, Pervin, Jesmin, Price, Joan, Kaur, Lovejeet, Al Mahmud, Abdullah, Thanh, Le, Care, Angharad, Landero, Julio, Combs, Gerald, Belling, Elizabeth, Chappell, Joanne, Chen, Jing, Kong, Fansheng, Lacher, Craig, Ahmed, Salahuddin, Chowdhury, Nabidul, Rahman, Sayedur, Kabir, Furqan, Nisar, Imran, Hotwani, Aneeta, Mehmood, Usma, Nizar, Ambreen, Khalid, Javairia, Dhingra, Usha, Dutta, Arup, Ali, Said, Aftab, Fahad, Juma, Mohammed, Rahman, Monjur, Ahmed, Tahmeed, Islam, M, Vwalika, Bellington, Musonda, Patrick, Ashorn, Ulla, Maleta, Kenneth, Hallman, Mikko, Goodfellow, Laura, Gupta, Juhi, Alfirevic, Ana, Murphy, Susan, Ryckman, Kelli, Murray, Jeffrey, Bahl, Rajiv, Litch, James, Baruch-Gravett, Courtney, Sopory, Shailaja, Chandra Mouli Natchu, Uma, Kumar, Pavitra, Kumari, Neha, Thiruvengadam, Ramachandran, Singh, Atul, Kumar, Pankaj, Alfirevic, Zarko, Baqui, Abdullah, Bhatnagar, Shinjini, Hirst, Jane, Hoyo, Cathrine, Jehan, Fyezah, Jelliffe-Pawlowski, Laura, Rahman, Anisur, Roth, Daniel, Sazawal, Sunil, Stringer, Jeffrey, Ashorn, Per, Zhang, Ge, Muglia, Louis, Rand, Larry

المصدر: American Journal of Clinical Nutrition. 119(1)

مصطلحات موضوعية: acute-phase reactants, copper, gestational duration, inflammation, low- and middle-income countries, nutrition, pregnancy, preterm birth, Pregnancy, Female, Humans, Infant, Newborn, Premature Birth, Copper, Gestational Age, Live Birth, Inflammation, Risk Factors

الوصف: BACKGROUND: Copper (Cu), an essential trace mineral regulating multiple actions of inflammation and oxidative stress, has been implicated in risk for preterm birth (PTB). OBJECTIVES: This study aimed to determine the association of maternal Cu concentration during pregnancy with PTB risk and gestational duration in a large multicohort study including diverse populations. METHODS: Maternal plasma or serum samples of 10,449 singleton live births were obtained from 18 geographically diverse study cohorts. Maternal Cu concentrations were determined using inductively coupled plasma mass spectrometry. The associations of maternal Cu with PTB and gestational duration were analyzed using logistic and linear regressions for each cohort. The estimates were then combined using meta-analysis. Associations between maternal Cu and acute-phase reactants (APRs) and infection status were analyzed in 1239 samples from the Malawi cohort. RESULTS: The maternal prenatal Cu concentration in our study samples followed normal distribution with mean of 1.92 μg/mL and standard deviation of 0.43 μg/mL, and Cu concentrations increased with gestational age up to 20 wk. The random-effect meta-analysis across 18 cohorts revealed that 1 μg/mL increase in maternal Cu concentration was associated with higher risk of PTB with odds ratio of 1.30 (95% confidence interval [CI]: 1.08, 1.57) and shorter gestational duration of 1.64 d (95% CI: 0.56, 2.73). In the Malawi cohort, higher maternal Cu concentration, concentrations of multiple APRs, and infections (malaria and HIV) were correlated and associated with greater risk of PTB and shorter gestational duration. CONCLUSIONS: Our study supports robust negative association between maternal Cu and gestational duration and positive association with risk for PTB. Cu concentration was strongly correlated with APRs and infection status suggesting its potential role in inflammation, a pathway implicated in the mechanisms of PTB. Therefore, maternal Cu could be used as potential marker of integrated inflammatory pathways during pregnancy and risk for PTB.

وصف الملف: application/pdf

الوصول الحر: https://escholarship.org/uc/item/0s28f2qzTest