Chitosan-tripolyphosphate (CTPP) beads were prepared using in-liquid curing method and used for the adsorption of uranium from aqueous solution. Beads were prepared at two different cross-linking ...densities by adjusting the pH of the tripolyphosphate solution. The synthesized beads were characterized using FTIR spectroscopy before and after adsorption of uranium. Beads having higher cross-linking are found to have better adsorption capacity for uranium. Factors that influence the uranium adsorption onto CTPP beads such as solution pH, contact time and initial uranium concentration were studied in detail. The experimental results were fitted into Langmuir and Freundlich adsorption isotherms. From Langmuir adsorption model the adsorption capacity of CTPP beads for uranium is estimated as 236.9mg/g. Pseudo-first order, pseudo-second order and intraparticle diffusion model were applied to the observed kinetics data and the results shows that the pseudo-second order model is more suitable to explain the kinetics of adsorption of uranium on CTPP beads. FTIR spectroscopic characterization of the beads showed that the phosphate groups may be more responsible for the adsorption of uranium on CTPP beads.
Single-Atom Spin-Flip Spectroscopy Heinrich, A. J.; Gupta, J. A.; Lutz, C. P. ...
Science (American Association for the Advancement of Science),
10/2004, Volume:
306, Issue:
5695
Journal Article
Peer reviewed
Open access
We demonstrate the ability to measure the energy required to flip the spin of single adsorbed atoms. A low-temperature, high-magnetic field scanning tunneling microscope was used to measure the spin ...excitation spectra of individual manganese atoms adsorbed on Al2O3islands on a NiAl surface. We find pronounced variations of the spin-flip spectra for manganese atoms in different local environments.
Results of room-temperature Raman scattering studies of ultrathin graphitic films supported on Si (100)/SiO2 substrates are reported. The results are significantly different from those known for ...graphite. Spectra were collected using 514.5 nm radiation on films containing from n = 1 to 20 graphene layers, as determined by atomic force microscopy. Both the first- and second-order Raman spectra show unique signatures of the number of layers in the film. The nGL film analogue of the Raman G-band in graphite exhibits a Lorentzian line shape whose center frequency shifts linearly relative to graphite as ∼1/n (for n = 1 ωG ≈ 1587 cm-1). Three weak bands, identified with disorder-induced first-order scattering, are observed at ∼1350, 1450, and 1500 cm-1. The ∼1500 cm-1 band is weak but relatively sharp and exhibits an interesting n-dependence. In general, the intensity of these D-bands decreases dramatically with increasing n. Three second-order bands are also observed (∼2450, ∼2700, and 3248 cm-1). They are analogues to those observed in graphite. However, the ∼2700 cm-1 band exhibits an interesting and dramatic change of shape with n. Interestingly, for n < 5 this second-order band is more intense than the G-band.
Interactions between tumor cells and cancer-associated fibroblasts (CAFs) in the tumor microenvironment significantly influence cancer growth and metastasis. Transforming growth factor-β (TGF-β) is ...known to be a critical mediator of the CAF phenotype, and osteopontin (OPN) expression in tumors is associated with more aggressive phenotypes and poor patient outcomes. The potential link between these two pathways has not been previously addressed. Utilizing in vitro studies using human mesenchymal stem cells (MSCs) and MDA-MB231 (OPN+) and MCF7 (OPN-) human breast cancer cell lines, we demonstrate that OPN induces integrin-dependent MSC expression of TGF-β1 to mediate adoption of the CAF phenotype. This OPN-TGF-β1 pathway requires the transcription factor, myeloid zinc finger 1 (MZF1). In vivo studies with xenotransplant models in NOD-scid mice showed that OPN expression increases cancer growth and metastasis by mediating MSC-to-CAF transformation in a process that is MZF1 and TGF-β1 dependent. We conclude that tumor-derived OPN engenders MSC-to-CAF transformation in the microenvironment to promote tumor growth and metastasis via the OPN-MZF1-TGF-β1 pathway.
In the framework of quantum chromodynamics (QCD), parton distribution functions (PDFs) quantify how the momentum and spin of a hadron are divided among its quark and gluon constituents. Two main ...approaches exist to determine PDFs. The first approach, based on QCD factorization theorems, realizes a QCD analysis of a suitable set of hard-scattering measurements, often using a variety of hadronic observables. The second approach, based on first-principle operator definitions of PDFs, uses lattice QCD to compute directly some PDF-related quantities, such as their moments. Motivated by recent progress in both approaches, in this document we present an overview of lattice-QCD and global-analysis techniques used to determine unpolarized and polarized proton PDFs and their moments. We provide benchmark numbers to validate present and future lattice-QCD calculations and we illustrate how they could be used to reduce the PDF uncertainties in current unpolarized and polarized global analyses. This document represents a first step towards establishing a common language between the two communities, to foster dialogue and to further improve our knowledge of PDFs.
We examine the relationship between corporate cash holdings and promoter ownership for a sample of Indian non-financial firms. Consistent with the arguments of the ‘efficient monitoring hypothesis’, ...our results broadly suggest that promoter ownership is negatively associated with cash holdings, thereby highlighting the role of large owners in preventing cash accretion in an emerging market context. Indicating prominent influence of corporate ownership on cash management, we find that corporate non-promoter ownership is also negatively related with cash holdings. With regard to promoter ownership of foreign entities, our results suggest that cash holdings share a U-shaped relationship with ownership of foreign promoter corporations. In addition, our findings provide weak evidence to support a more pronounced negative association between cash holdings and promoter ownership for group-affiliated firms as compared to non-affiliated firms since the former faces lower financial constraints on account of access to internal capital markets. Finally, we perform long-term effect analysis in order to reinforce robustness of our results.
•Corporate cash holdings and promoter ownership are negatively related.•This relationship varies across different types of promoters.•Cash holdings have U-shaped relation with promoter ownership of foreign corporates.•Non-promoter corporate ownership is negatively related with cash holdings.
•We, the authors, would like to express our great appreciation to you and reviewers for giving us an opportunity to improve our paper. We have carefully studied the comments and suggestions that were ...put forward by the reviewers. We have revised the manuscript by incorporating all the suggestions (highlighted with red colour) given by the reviewers and the revisions are mentioned in the ’Response to the reviewers’ section along with the cover letter.
In this paper, a new protection scheme, based on rate-of-rise of fault current with adaptive current threshold, is proposed to provide fast and accurate fault detection in DC microgrid. It utilizes the peculiarity involved with the DC faults i.e. the DC fault current increases very fast to a high value. Therefore, under the scheme, each relay detects a fault if the time interval, during which the fault current rises from minimum to maximum value, is below the predefined threshold value. The efficacy of the proposed scheme is validated on a 380V ring-type DC microgrid simulated considering different fault conditions with various fault resistance values at different fault locations. The simulation results obtained under distinct operating conditions indicate high selectivity and high speed of operation of the proposed scheme for fault detection and isolation (less than 1ms). The proposed scheme is compared with the existing protection techniques in the literature which exhibits comparatively better effectiveness and reliability of the proposed technique.
ABSTRACT
In this work, we present the results of 1 yr of upgraded Giant Metrewave Radio Telescope timing measurements of PSR J0514−4002A, a 4.99-ms pulsar in a 18.8-d eccentric ($e = 0.89$) orbit ...with a massive companion located in the globular cluster NGC 1851. Combining these data with earlier Green Bank Telescope data, we greatly improve the precision of the rate of advance of periastron, $\dot{\omega} = 0.0129592(16)\, \deg \, \rm yr^{-1}$ which, assuming the validity of general relativity, results in a much refined measurement of the total mass of the binary, $M_{\rm tot} = 2.4730(6) \, \mathrm{M}_{\odot }$. Additionally, we measure the Einstein delay parameter, γ, something that has never been done for any binary system with an orbital period larger than ${\sim}$10 h. The measured value, $\gamma = 0.0216(9) \, \rm s$, is by far the largest for any binary pulsar. Furthermore, we measure the proper motion of the system ($\mu _{\alpha } = 5.19(22)$ and $\mu _{\delta } = -0.56(25)\rm ~mas ~ yr^{-1}$), which is not only important for analysing its motion in the cluster, but is also essential for a proper interpretation of γ, given the latter parameter’s correlation with the variation of the projected semimajor axis. The measurements of γ and the proper motion enable a separation of the system component masses: we obtain a pulsar mass of $M_{\rm p} = 1.25^{+0.05}_{-0.06} \, \mathrm{M}_{\odot }$ and a companion mass of $M_{\rm c} = 1.22^{+0.06}_{-0.05} \, \mathrm{M}_{\odot }$. This raises the possibility that the companion is also a neutron star. Searches for radio pulsations from the companion have thus far been unsuccessful; hence, we cannot confirm the latter hypothesis. The low mass of this millisecond pulsar – one of the lowest ever measured for such objects – clearly indicates that the recycling process can be achieved with a relatively small amount of mass transfer.
Molecule Cascades Heinrich, A. J.; Lutz, C. P.; Gupta, J. A. ...
Science (American Association for the Advancement of Science),
11/2002, Volume:
298, Issue:
5597
Journal Article
Peer reviewed
Open access
Carbon monoxide molecules were arranged in atomically precise configurations, which we call "molecule cascades," where the motion of one molecule causes the subsequent motion of another, and so on in ...a cascade of motion similar to a row of toppling dominoes. Isotopically pure cascades were assembled on a copper (111) surface with a low-temperature scanning tunneling microscope. The hopping rate of carbon monoxide molecules in cascades was found to be independent of temperature below 6 kelvin and to exhibit a pronounced isotope effect, hallmarks of a quantum tunneling process. At higher temperatures, we observed a thermally activated hopping rate with an anomalously low Arrhenius prefactor that we interpret as tunneling from excited vibrational states. We present a cascade-based computation scheme that has all of the devices and interconnects required for the one-time computation of an arbitrary logic function. Logic gates and other devices were implemented by engineered arrangements of molecules at the intersections of cascades. We demonstrate a three-input sorter that uses several AND gates and OR gates, as well as the crossover and fan-out units needed to connect them.
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