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Gastrointestinal (GI) cancers refer to a group of malignancies associated with the GI tract (GIT). Like other solid tumors, hypoxic regions consistently feature inside the GI tumor microenvironment (TME) and contribute towards met...
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Gastrointestinal (GI) cancers refer to a group of malignancies associated with the GI tract (GIT). Like other solid tumors, hypoxic regions consistently feature inside the GI tumor microenvironment (TME) and contribute towards metabolic reprogramming of tumor-resident cells by modulating hypoxia-induced factors. We highlight here how the metabolic crosstalk between cancer cells and immune cells generate immunosuppressive environment inside hypoxic tumors. Given the fluctuating nature of tumor hypoxia, the metabolic fluxes between immune cells and cancer cells change dynamically. These changes alter cellular phenotypes and functions, resulting in the acceleration of cancer progression. These evolved properties of hypoxic tumors make
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Manipulating light at the sub-wavelength level is a crucial feature of surface plasmon resonance (SPR) properties for a wide range of nanostructures. Noble metals like Au and Ag are most commonly used as SPR materials. Significant...
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Manipulating light at the sub-wavelength level is a crucial feature of surface plasmon resonance (SPR) properties for a wide range of nanostructures. Noble metals like Au and Ag are most commonly used as SPR materials. Significant attention is being devoted to identify and develop non-noble metal plasmonic materials whose optical properties can be reconfigured for plasmonic response by structural phase changes. Chromium (Cr) which supports plasmon resonance, is a transition metal with shiny finished, highly non-corrosive, and bio-compatible alloys, making it an alternative plasmonic material. We have synthesized Cr micro-rods from a bi-layer of Cr/Au thin films, which evolves from face centered cubic to hexagonal close packed (HCP) phase by thermal activation in a forming gas ambient. We employed optical absorption spectroscopy and cathodoluminescence (CL) imaging spectroscopy to observe the plasmonic modes from the Cr micro-rod. The origin of three emission bands that spread over the UV-Vis-IR energy range is established theoretically by considering the critical points of the second-order derivative of the macroscopic dielectric function obtained from density functional theory (DFT) matches with interband/intraband transition of electrons observed in density of states versus energy graph. The experimentally observed CL emission peaks closely match the s-d and d-d band transition obtained from DFT calculations. Our findings on plasmonic modes in Cr(HCP) phase can expand the range of plasmonic material beyond noble metal with tunable plasmonic emissions for plasmonic-based optical technology.
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In recent years, catalysis with base metal manganesehas receiveda significant amount of interest. Catalysis with manganese complexeshaving N-heterocyclic carbenes (NHCs) is relativelyunderdeveloped in comparison to the extensively...
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In recent years, catalysis with base metal manganesehas receiveda significant amount of interest. Catalysis with manganese complexeshaving N-heterocyclic carbenes (NHCs) is relativelyunderdeveloped in comparison to the extensively investigated manganesecatalysts possessing pincer ligands (particularly phosphine-basedligands). Herein, we describe the synthesis of two imidazolium saltsdecorated with picolyl arms (L ( 1 ) and L ( 2 )) as NHC precursors.Facile coordination of L ( 1 ) and L ( 2 ) with MnBr(CO)(5) in thepresence of a base resulted in the formation manganese(I)-NHCcomplexes (1 and 2) as an air-stable solidin good isolated yield. Single-crystal X-ray analysis revealed thestructure of the cationic complexes [Mn(CO)(3)(NHC)][PF6] with tridentate N,C,N binding of the NHC ligand in a facilefashion. Along with a few known manganese(I) complexes, these Mn(I)-NHCcomplexes 1 and 2 were tested for the hydrosilylationof terminal alkynes. Complex 1 was proved to be an effectivecatalyst for the hydrosilylation of terminal alkynes with good selectivitytoward the less thermodynamically stable & beta;-(Z)-vinylsilanes. This method provided good regioselectivity (anti-Markovnikov addition) and stereoselectivity (& beta;-(Z)-product). Experimental evidence suggested that the presenthydrosilylation pathway involved an organometallic mechanism withmanganese(I)-silyl species as a possible reactive intermediate.
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In recent years, catalysis with base metal manganesehas receiveda significant amount of interest. Catalysis with manganese complexeshaving N-heterocyclic carbenes (NHCs) is relativelyunderdeveloped in comparison to the extensively...
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In recent years, catalysis with base metal manganesehas receiveda significant amount of interest. Catalysis with manganese complexeshaving N-heterocyclic carbenes (NHCs) is relativelyunderdeveloped in comparison to the extensively investigated manganesecatalysts possessing pincer ligands (particularly phosphine-basedligands). Herein, we describe the synthesis of two imidazolium saltsdecorated with picolyl arms (L ( 1 ) and L ( 2 )) as NHC precursors.Facile coordination of L ( 1 ) and L ( 2 ) with MnBr(CO)(5) in thepresence of a base resulted in the formation manganese(I)-NHCcomplexes (1 and 2) as an air-stable solidin good isolated yield. Single-crystal X-ray analysis revealed thestructure of the cationic complexes [Mn(CO)(3)(NHC)][PF6] with tridentate N,C,N binding of the NHC ligand in a facilefashion. Along with a few known manganese(I) complexes, these Mn(I)-NHCcomplexes 1 and 2 were tested for the hydrosilylationof terminal alkynes. Complex 1 was proved to be an effectivecatalyst for the hydrosilylation of terminal alkynes with good selectivitytoward the less thermodynamically stable & beta;-(Z)-vinylsilanes. This method provided good regioselectivity (anti-Markovnikov addition) and stereoselectivity (& beta;-(Z)-product). Experimental evidence suggested that the presenthydrosilylation pathway involved an organometallic mechanism withmanganese(I)-silyl species as a possible reactive intermediate.
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We present a detailed investigation on thickness-dependent third-order (chi(3)) nonlinear optical properties of RF-sputtered WSe2 thin-films using ultrashort pulses centered at different excitation wavelengths. The single-beam Z-s...
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We present a detailed investigation on thickness-dependent third-order (chi(3)) nonlinear optical properties of RF-sputtered WSe2 thin-films using ultrashort pulses centered at different excitation wavelengths. The single-beam Z-scan based investigation in the visible spectrum reveals a predominant Pauli-blocking effect led saturable absorption or optical limiting in WSe2 thin-films. The study also explores the dispersion in third-order nonlinear susceptibility (chi(3)) in WSe2 thin films. Interestingly, WSe2 thin-films of any thickness exhibit a self-focusing effect depicting a positive nonlinear refractive index (n2 > 0). The frequency-dependent nonlinear absorption (beta) bear distinct correlations with the bandgap of the films which is also investigated through density-functional-theory (DFT) based simulations. The alteration in bandstructure is primarily due to the Se-deficiency induced defect bands in WSe2 thin-films which has discernible impact on the optical
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Development of simple synthetic methods fromreadily available compounds to complex products is of utmostinterest in modern synthesis. Catalytic synthesis of cyclopropanesis important for diverse chemical applications. We present a...
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Development of simple synthetic methods fromreadily available compounds to complex products is of utmostinterest in modern synthesis. Catalytic synthesis of cyclopropanesis important for diverse chemical applications. We present amethod for the transformation of readily accessible alpha,beta-unsaturatedketones (chalcones) to cyclopropanes. A simple base, KOH,catalyzed the selective reduction of the enone carbonylfunctionality, dehydrogenative silylation, and deoxygenative cyclization of chalcones to provide the cyclopropane products.Chalcones with extended conjugation and 4-chromanone-based substrates also provided the corresponding cyclopropanes. One-potsynthesis of cyclopropanes directly from industrial feedstock compounds such as ketones and aldehydes is also demonstrated usingcatalytic KOH for both intermolecular condensation and dehydrogenative silylation-deoxygenative intramolecular cyclization cascade
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Helicobacter pylori-mediated gastric carcinogenesis involves upregulation of the E3 ubiquitin ligase Siah2 and its phosphorylation-mediated stabilization. This study elucidates a novel mechanism of oxidative stress regulation by p...
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Helicobacter pylori-mediated gastric carcinogenesis involves upregulation of the E3 ubiquitin ligase Siah2 and its phosphorylation-mediated stabilization. This study elucidates a novel mechanism of oxidative stress regulation by phosphorylated Siah2 in H. pylori-infected gastric epithelial cancer cells (GECs). We identify that H. pylori-mediated Siah2 phosphorylation at the 6th serine residue (P-S-6-Siah2) enhances proteasomal degradation of the 78-kDa glucose-regulated protein (GRP78) possessing antioxidant functions. S-6 phosphorylation stabilizes Siah2 and P-S-6-Siah2 potentiates H. pylori-mediated reactive oxygen species (ROS) generation. However, infected S6A phospho-null Siah2-expressing cells have decreased cellular GRP78 level as surprisingly these cells release GRP78 to a higher extent and accumulate significantly higher ROS than the wild type (WT) Siah2 construct-expressing cells. Ectopic expression of GRP78 prevents the loss of mitochondrial membrane potential and cellular ROS accumulation caused by H. pylori. H. pylori-induced mitochondrial damage and mitochondrial membrane potential loss are potentiated in Siah2-overexpressing cells but these effects are further enhanced in S6A-expressing cells. This study also confirms that while phosphorylation-mediated Siah2 stabilization optimally upregulates aggresome accumulation, it suppresses autophagosome formation, thus decreasing the dependency on the latter mechanism in regulating cellular protein abundance. Disruption of the phospho-Siah2-mediated aggresome formation impairs proliferation of infected GECs. Thus, Siah2 phosphorylation has diagnostic and therapeutic significance in H. pylori-mediated gastric cancer (GC).
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Using the blast-wave model, we explore the effect of electric fields on spectra and flow harmonics (especially the elliptic flow) for charged pions and protons. We incorporate the first-order correction to the single-particle dist...
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Using the blast-wave model, we explore the effect of electric fields on spectra and flow harmonics (especially the elliptic flow) for charged pions and protons. We incorporate the first-order correction to the single-particle distribution function due to the electric fields and the dissipative effect while calculating the invariant yields of hadrons in the Cooper-Frye prescription at the freezeout hypersurface. We find a noticeable correction to the directed and elliptic flow of pions and protons for unidirectional and azimuthal asymmetric electric fields of a magnitude similar to m(p)(2) in the transverse plane. Further, we observe mass dependency of the directed flow generated due to the electric fields. The splitting of particle and antiparticle's elliptic flow due to the electric fields is also discussed.
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Pristine fullerene (C-60), without an anchor group, can form a complex with 12-faceted dodecahedron CsPbBr3 perovskite nanocrystals (PNCs) owing to a greater number of binding facets of the latter. The PNC-fullerene hybrid with op...
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Pristine fullerene (C-60), without an anchor group, can form a complex with 12-faceted dodecahedron CsPbBr3 perovskite nanocrystals (PNCs) owing to a greater number of binding facets of the latter. The PNC-fullerene hybrid with optically rich properties exhibits efficient photoinduced electron transfer (PET) from optically pumped PNCs to fullerene. While time-correlated single-photon counting deduced the intrinsic PET time scale (similar to 1.8 ns per quencher) utilizing photoluminescence lifetime quenching of the PNCs, the fluorescence correlation spectroscopy, on the other hand, determined the stability of the PNC-fullerene complex along with the associated time scale of the complexation reaction (tau(R) similar to 500 mu s). Complex formation assures an insignificant role of solvent diffusion in our bimolecular PET study. Considering the inherently complex nature of the PET reaction that cannot be explained by a Stern-Volmer analysis, we employed a stochastic model initially proposed by Tachiya to render insight into the PET mechanism, assuming fullerenes distributed on the PNC surface follow Poisson statics. The fast intrinsic PET time scale in the one-to-one PNC-fullerene hybrid points toward the fact that the dramatic improvement of efficiencies of the polyhedral PNC-based devices can become a reality.
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We have studied the effect of deposition pressure on the magnetization reversal, domains, anisotropy and Gilbert damping constant in the ferromagnetic (CoFeB and Co) single and bilayer samples. Hysteresis measured by magneto-optic...
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We have studied the effect of deposition pressure on the magnetization reversal, domains, anisotropy and Gilbert damping constant in the ferromagnetic (CoFeB and Co) single and bilayer samples. Hysteresis measured by magneto-optic Kerr microscopy for the single layer films prepared at higher deposition pressure indicate no change of loop shape i.e. isotropic behaviour. An enhancement of anisotropy has been observed in the bilayer samples than the single layer samples prepared at a particular deposition condition. However, increasing the deposition pressure to 50 sccm for the bilayer samples, anisotropy gets reduced. For single layer Co film deposited at 10 sccm exhibits branch and patch like domains for different angle between the easy axis and the external magnetic field. However, the Co film deposited at 50 sccm exhibits ripple like domains. In the case of single layer CoFeB, branch and patch like domains are observed deposited at 10 sccm. Patch like domains are found for the CoFeB films deposited at 50 sccm. Pinned labyrinth and ripple kind of magnetic domains along with the big branch domains are found in the bilayer samples. The pinned domains may be due to the interfacial exchange coupling. Similar values of damping constants have been observed for different thin films prepared at different deposition pressure.
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