Metal ions in macrophage antimicrobial pathways: emerging roles for zinc and copper

The immunomodulatory and antimicrobial properties of zinc and copper have long been appreciated. In addition, these metal ions are also essential for microbial growth and survival. This presents opportunities for the host to either harness their antimicrobial properties or limit their availability as defence strategies. Recent studies have shed some light on mechanisms by which copper and zinc regulation contribute to host defence, but there remain many unanswered questions at the cellular and molecular levels. Here we review the roles of these two metal ions in providing protection against infectious diseases in vivo, and in regulating innate immune responses. In particular, we focus on studies implicating zinc and copper in macrophage antimicrobial pathways, as well as the specific host genes encoding zinc transporters (SLC30A, SLC39A family members) and CTRs (copper transporters, ATP7 family members) that may contribute to pathogen control by these cells

Bane to boon: tailored defect induced bright red luminescence from cuprous iodide nanophosphors for on-demand rare-earth-free energy-saving lighting applications

The long standing controversy concerning the defect band in cuprous iodide (CuI) has been addressed in this paper from a technological point of view of its solid state lighting application. Recently, solid state lighting technology using nanophosphors has been proposed as the prime candidate in the energy saving lighting paradigm. Herein, we demonstrate a novel rare-earth free and non-toxic CuI nanophosphor, which has been synthesized via a facile solvothermal route. These nanophosphors are able to show ultra-bright and stable red emission under near UV excitation. The spectral features of this easily derived nanophosphor are not less than any rare-earth or cadmium based conventional phosphor. Furthermore, it has been conclusively verified that the deep red emission is strongly related to the excess iodine induced optimized defect level engineering in the band structure. The concepts and results presented in this paper clearly establish that the CuI nanophosphor is a promising 'green' material for the state-ofthe-art rare-earth free lighting and display applications

Raman Spectroscopic Observation of Gradual Polymorphic Transition and Phonon Modes in CuPc Nanorod

A Raman scattering investigation of a single α-CuPc nanorod is demonstrated here within the temperature range 300–770 K. From the typical thermal dispersion of Raman shift and phonon line width of in-plane B_1g mode at 1526 cm^–1, the metastable α polymorph is observed to undergo unambiguous phase transition to thermally stable β phase. The phase transition temperature (456 K) is observed to be significantly lower than that reported for bulk samples. Extensive computation of normal modes associated with both α- and β-CuPc reveal that the “fingerprint” domain across 1300–1600 cm^–1 is particularly sensitive to this polymorphic transition where a silent B_2g mode appears at 1303 cm^–1 in the spectral vicinity of molecular edge vibration sensitive A_g–B_g Davydov doublet

Controlling Nonradiative Transition Centers in Eu³⁺ Activated CaSnO₃ Nanophosphors through Na⁺ Co-Doping: Realization of Ultrabright Red Emission along with Higher Thermal Stability

Solid-state lighting (SSL) and field emission based display (FED) devices collectively encompass a major fraction of contemporary research efforts and thus development of a newer generation of highly luminescent nanophosphors presently defines a critical juncture for further development of this still somewhat-nascent field. However, the low efficiency of red phosphors constitutes a principal bottleneck for commercialization of such devices. Herein, we present a red light emitting highly luminescent Na⁺ codoped CaSnO₃:Eu³⁺ nanophosphor with an average particle size of 32 nm that has been synthesized by a modified sol–gel technique. The resultant nanophosphor exhibits bright red emission under both UV and low voltage electron beam excitations. Furthermore, quantitative assessments of photoluminescence (PL) signatures for Eu³⁺ doped and Na⁺ codoped CaSnO₃:Eu³⁺ nanophosphors conclusively demonstrate that Na⁺ codoping facilitates an almost 4-fold increase in the luminescence intensity coupled with significant improvement in thermal stability. In addition, charge compensation by incorporation of Na⁺ leads to an increased order of radiative transition and thereby increases the color purity and lifetime of radiative transition. Obtained results firmly and unambiguously establish the bright and revolutionary prospects of this new type of nanophosphor in the rapidly emerging field of solid state lighting and FED devices

Enhanced Ultraviolet Emission from Mg Doped SnO₂ Nanocrystals at Room Temperature and Its Modulation upon H₂ Annealing

Photoluminescence (PL) and absorption features of high-quality nanocrystalline Sn_1‑<i>x</i>Mg_<i>x</i>O₂ series (0 ≤ <i>x</i> ≤ 0.03) were investigated at room temperature. Although particle sizes of as-synthesized samples are larger than Bohr radius (<i>a</i>_B), Fermi edge absorption is observed both in undoped and doped samples. Incorporation of Mg 2p states near valence band maxima (VBM) widens the band gap (<i>E</i>_g) consistently and stable, high-yield room temperature free exciton (RTFE) emission (3.81 eV) results. Deconvolution of each UV emission reveals band tail emission (3.54 eV) along with excitonic recombination. A feeble green emission (2.34 eV) is also observed and its intensity strongly depends on tensile strain (η) and formation energy (<i>E</i>_f) of oxygen vacancy (V_O) and hydrogen at V_O (<i>H</i>_O). H₂ annealing at 300 °C introduces interesting doping dependent modulation in UV emission intensity. Elemental projective density of states (DOS) exhibit Sn 5s–H 1s hybridization in undoped passivated supercell and Mg 2p–H 1s hybridization in doped passivated supercells. Band gap widening and doping dependent emission modulation in both passivated and unpassivated samples are explained by first principles investigation. This study points to the scope of FE emission enhancement technique at room temperature for optoelectronic applications based on alkaline earth metal doping in direct gap metal oxide semiconductors

Local Field Enhancement-Induced Enriched Cathodoluminescence Behavior from CuI-RGO Nanophosphor Composite for Field-Emission Display Applications

Field-emission displays (FEDs) constitute one of the major foci of the cutting edge materials research because of the increasingly escalating demand for high-resolution display panels. However, poor efficiencies of the concurrent low voltage cathodoluminescence (CL) phosphors have created a serious bottleneck in the commercialization of such devices. Herein we report a novel CuI-RGO composite nanophosphor that exhibits bright red emission under low voltage electron beam excitation. Quantitative assessment of CL spectra reveals that CuI-RGO nanocomposite phosphor leads to the 4-fold enhancement in the CL intensity as compared to the pristine CuI counterpart. Addition of RGO in the CuI matrix facilitates efficient triggering of luminescence centers that are activated by local electric field enhancement at the CuI-RGO contact points. In addition, conducting RGO also reduces the negative loading problem on the surface of the nanophosphor composite. The concept presented here opens up a novel generic route for enhancing CL intensity of the existing (nano)­phosphors as well as validates the bright prospects of the CuI-RGO composite nanophosphor in this rapidly growing field

Realizing Direct Gap, Polytype, Group IIIA Delafossite: Ab Initio Forecast and Experimental Validation Considering Prototype CuAlO₂

Modification of orbital interactions by suitable “orbital alloying” is a necessity to obtain direct gap group IIIA delafossite with shallow acceptor states, which unfortunately have never been realized. This Letter promotes an optimistic trend regarding the oxide delafossite family to obtain significant hole delocalization in the vicinity of the (Cu 3d + O 2p) valence band with an unprecedented direct gap by chalcogen (Ch = S, Se) doping-induced polytype formation (<i>R</i>3̅<i>m</i> → <i>P</i>3<i>m</i>1). Polytypism and a modulated valence band in prototype CuAlO₂ are “observed” upon sulfur incorporation at the O site. From the exhibition of better transport properties, weak local σ symmetry between Cu 3d_<i>z</i>² and O 2p_<i>z</i> states are reflected in the doped material. Dispersion of Cu 3d character by incorporating shallower acceptor (Ch 3p) states is concluded upon analyzing the photoemission spectra of the valence band