Crystal Core Research Articles

Glyconanofluorides as Immunotracers with a Tunable Core Composition for Sensitive Hotspot Magnetic Resonance Imaging of Inflammatory Activity.

Nature-inspired nanosized formulations based on an imageable, small-sized inorganic core scaffold, on which biomolecules are assembled to form nanobiomimetics, hold great promise for both early diagnostics and developed therapeutics. Nevertheless, the fabrication of nanobiomimetics that allow noninvasive background-free mapping of pathological events with improved sensitivity, enhanced specificity, and multiplexed capabilities remains a major challenge. Here, we introduce paramagnetic glyconanofluorides as small-sized (<10 nm) glycomimetics for immunotargeting and sensitive noninvasive in vivo19F magnetic resonance imaging (MRI) mapping of inflammation. A very short T1 relaxation time (70 ms) of the fluorides was achieved by doping the nanofluorides’ solid crystal core with paramagnetic Sm3+, resulting in a significant 8-fold enhancement in their 19F MRI sensitivity, allowing faster acquisition and improved detectability levels. The fabricated nanosized glycomimetics exhibit significantly enhanced uptake within activated immune cells, providing background-free in vivo mapping of inflammatory activity, demonstrated in both locally induced inflammation and clinically related neuropathology animal models. Fabricating two types of nanofluorides, each with a distinct chemical shift, allowed us to exploit the color-like features of 19F MRI to map, in real time, immune specificity and preferred targetability of the paramagnetic glyconanofluorides, demonstrating the approach’s potential extension to noninvasive multitarget imaging scenarios that are not yet applicable for nanobiomimetics based on other nanocrystal cores.

Recycling of mullite from high-alumina coal fly ash by a mechanochemical activation method: Effect of particle size and mechanism research

High-alumina coal fly ash (HAFA) is a special solid waste since its alumina content can reach 40–50 wt%, which is seen as a potential resource for mullite material production. However, obtaining an ideal mullite material from HAFA is difficult because of its low Al2O3/SiO2 mass ratio. In this work, the microstructure characteristics of HAFA were systematically analyzed by combining multiple characterization techniques. It was found that HAFA had a core-shell structure with a mullite/corundum crystal core and a silica-rich amorphous phase shell. The novel mechanochemical activation–desilication process was used to remove amorphous phase from HAFA and elevate the Al2O3/SiO2 mass ratio. In particular, the effect of particle size after mechanical treatment and mechanism of the desilication process were extensively investigated. On decreasing the particle size, a high leaching rate of alumina was achieved during mechanochemical activation, thus generating a hydroxysodalite coating layer as desilication was suppressed, and the amorphous phase was effectively removed. The mineralogical phase of the desilicated HAFA is mainly mullite and corundum, and the Al2O3/SiO2 mass ratio was elevated from 1.29 to 3.02. Mullite refractory obtained from the desilicated HAFA exhibited excellent physical properties. This study provides insights into further high-valued utilization of HAFA.

Liquid crystal core polymer fiber mat electronic gas sensors

ABSTRACT Electrospun liquid crystal fibres are promising media for gas sensing. However, accurately quantifying their response has been a challenge and until now limited to optical changes which utilise lasers and bulky detectors hindering the use for wear-able sensors. Herein, we make use of the resistive changes of the liquid crystal core polymer fibre mats (LCC-PFM) when exposed to volatile organic compounds (VOC). We found that these LCC-PFMs show reversible sensing of acetone at room temperature with response (recovery) times of ~14 (21) seconds and sensitivity as low as 10 ppm. This is comparable to the currently used metal-oxide-based sensors which typically operate at temperatures above 200 °C. These fibre mats are flexible, lightweight and in principle, can be easily miniaturised for use as resistive sensors to as small as 10 μm linear dimensions.

Combined petrography, noble gas, stable isotope and fluid inclusion chemistry of carbonatites from Uganda: Implications for the origin of the carbonatite melt in continental rift setting

An integrated petrographic, fluid inclusion, noble gas, and stable isotope study was performed for the Late Oligocene, spatially associated Sukulu and Tororo carbonatite complexes in SE Uganda in order to understand their genesis and provide additional constraints on the evolution of the East African Rift System (EARS). Both carbonatite complexes comprise mainly ring-shaped calcio‑carbonatites with accessory primary magmatic phases, including olivine, phlogopite, aegirine and pyrochlore. Absent or low Na deficiency on the A-site and high F contents (0.4–1.2 apfu) reveal the magmatic origin of pyrochlore. In contrast, the corroded rims of olivine, Sr-enrichments of the rims of apatite, as well as the occurrence of Sr- and Mg-rich lamellae in calcite, coupled with the presence of barite, REE-witherite, siderite, pyrite, bastnäsite and galena as secondary phases imply a hydrothermal overprint of the primary magmatic mineral assemblage.Fluid inclusions found in the cores of clustered apatite crystals are primary, two-phase H2O + NaCl aqueous inclusions in Sukulu-, and two-, or multi-phase H2O + NaCl ± NaHCO3 ± other solid inclusions in Tororo Complex. In the gas phase of some inclusions small amounts of CO2 or CH4 have been detected by micro-Raman analysis. The estimated trapping temperature of 330–425 °C and pressure of 465–1330 bars using the accepted denudation rates calculated for the EARS as independent barometers, reveal subsolidus crystallization conditions for the intercrystalline clustered apatite aggregates. Stable C-O isotope compositions of both carbonatite complexes suggest ultimately a mantle origin for the carbonate phase.Helium, neon and argon isotope compositions, liberated by crushing of bulk rock, apatite and calcite samples, show a systematic variation between the analyzed phases. Relatively low 3He/4He ratios of apatite and pyroxene separates (<5.3 Ra) are accounted for by radiogenic production of 4He in these minerals, whereas the air-corrected values in calcite reach as high as 9.6 Ra, characteristic for plume sources. Whole-rock Ne isotope ratios provide evidence for a depleted MORB mantle (DMM) trend. Combined (21Ne/22Ne)EX (air-corrected 21Ne/22Ne ratio extrapolated to Ne-B composition Holland and Ballentine, 2006; Trieloff et al., 2000) versus 4He/3He are indicative of mixing of a plume-like and a DMM-like component in the source region of the parental carbonatite magmas, which is in contrast to some recent interpretations of recent/sub-recent magmas in the EARS. Based on new noble gas data from this study we argue that in the early phase of the magmatic activity of the EARS, a low-viscosity carbonatite magma may have intruded into the shallow crust rapidly, without any significant contamination by the sub-continental lithospheric mantle.Combined fluid inclusion data and noble gas results collectively imply that the carbonatites worldwide are carbothermal (hydrothermal) rather than purely magmatic products and that they crystallized at sub-solidus temperatures from dominantly magma-derived fluids.

Grain Size Variations Record Segregation of Residual Melts in Slow‐Spreading Oceanic Crust (Atlantis Bank, 57°E Southwest Indian Ridge)

AbstractBeneath slow‐spreading ridges, melt bodies are generally considered to represent ephemeral magma reservoirs filled with crystal mushes. Formation of the oceanic crust requires at least partial extraction of melts from these crystal mushes. However, melts collection and extraction are processes yet to be fully constrained. We investigate olivine gabbros from the plutonic section recovered at the IODP Hole U1473A, in the Atlantis Bank Oceanic Core Complex (Southwest Indian Ridge), to unravel (i) the process of melt migration through lower crustal crystal mushes, and (ii) the collection and segregation of melts forming discrete microgabbro intervals. Throughout the Hole, fine‐ to coarse‐grained intervals are widespread in olivine gabbros. Along the contacts, coarse‐grained minerals display resorbed grain boundaries against the fine‐grained minerals, suggesting partial dissolution by the melt crystallizing the fine‐grained material. Coarse‐grained plagioclase and clinopyroxene are zoned, showing progressive chemical evolution from more primitive crystal cores to more evolved crystal rims. Fine‐grained minerals are unzoned and chemically similar to rims of coarse‐grained minerals, indicating a genetic relationship. We attribute significant enrichments in the most incompatible elements of plagioclase and clinopyroxene to a magma evolution process associated with reactive melt migration. As temperature decreased, melts residual from the reactive processes were segregated in magma pockets that ultimately crystallize the fine‐grained intervals (microgabbros). We document, for the first time, that these microgabbros are crystallization products of melts modified by reactive melt migration; the melts were extracted from the crystal mush and accumulated into discrete melt‐rich zones. This process could have promoted partial extraction of those melts that in turn potentially contribute to Mid Ocean Ridge Basalts erupted at the seafloor.

Effect of CO2 Laser on Glazed Zircon Surface Complemented by ZrO2 Oxide

In this paper, the effect of CO2 laser on glaze-dental Zirconia ceramics after adding ZrO2 nanoparticles to glaze is introduced, and its improvement methods are studied. Specimens have been prepared using CAD/CAM dental machines and sintered at 1530o-C. Then the surface was glazed with VITA glaze plus (5% and 10%) Nano ZrO2. A 15W continuous CO2 laser was used as the indicator power to irradiate the glaze layer. The main phase of the ceramic substrate is tetragonal Zirconia, and the alumina content in the corundum phase is a certain percentage. The appearance of the varnish on the ceramic substrate changes the X-ray diffraction pattern through the appearance of new phases, which changes the crystallite size and the percentage of lattice strain. The range of grain size measured by atomic force microscopy was 88.46 nm to 62.18nm. In addition, the surface roughness was changed due to the appearance of crystal cores and grain growth. In addition, the addition of ZrO2 and laser irradiation changed the residual stress on the surface, which was reflected in the hardness value increased from 575 kg/mm2 to 1215 kg/mm2 after the laser treatment with the addition of 5% ZrO2. Generally, in terms of the structure and hardness of the surface of the glaze layer, the addition of 5% ZrO2 is better than 10%. SEM tests also showed no cracks in the central part of the treated area. These characteristics increase hardness.

Evolution of the Magmatic-Hydrothermal System at the Santa Rita Porphyry Cu Deposit, New Mexico, USA: Importance of Intermediate-Density Fluids in Ore Formation

Abstract The Santa Rita porphyry Cu deposit in New Mexico, USA, is characterized by a stockwork of three vein types that differ in morphology, mineralogy, and associated alteration assemblages. Early quartz veins associated with potassic alteration are composed of recrystallized granular quartz grains that host ubiquitous hypersaline liquid and vapor-rich fluid inclusions. The early quartz likely formed at high (≳500°C) temperatures and lithostatic pressures. Hypogene Cu mineralization at Santa Rita is in sulfide veins that reopened or crosscut the early quartz veins. The sulfide veins are surrounded by alteration halos containing chlorite and K-feldspar. Rare quartz crystals are present in some of these chalcopyrite and pyrite veins. The cores of the quartz crystals contain hypersaline liquid and vapor-rich fluid inclusions, whereas the rims mostly contain hypersaline liquid inclusions. The quartz crystals are interpreted to have formed close to the ductile-brittle transition as a result of the pressure drop from lithostatic to hydrostatic conditions. Formation of the quartz crystals was postdated by the deposition of Cu sulfides. Grain boundaries between the quartz and the sulfide minerals are irregular in shape, with sulfide crosscutting growth zones in the quartz. The Cu sulfides are interpreted to have formed from intermediate-density fluids that form secondary fluid inclusion assemblages in all earlier-formed quartz types. Microthermometric investigations showed that these fluid inclusion assemblages homogenize at ~385° to 435°C by critical or near-critical behavior and have salinities of &amp;lt;10 wt % NaCl equiv. The precipitation of Cu sulfides occurred as a result of cooling of these fluids following their escape from the lithostatic into the hydrostatic realm. Retrograde quartz solubility caused the corrosion of earlier-formed quartz during Cu sulfide deposition. The youngest veins at Santa Rita are composed of quartz and pyrite. These veins are associated with intense sericite alteration that overprinted all earlier alteration assemblages. The late quartz hosts primary and secondary liquid-rich fluid inclusions, but no intermediate-density fluid inclusions were identified. This quartz vein type formed at temperatures &amp;lt;360°C and hydrostatic pressures. The paragenetic relationships show that hypogene Cu mineralization at Santa Rita postdated potassic alteration of the host rocks. The Cu mineralization was formed by cooling intermediate-density fluids with critical or near-critical densities as they escaped from lithostatic to hydrostatic conditions.

Textures, trace elements and Pb isotopes of pyrite from the Donggushan tungsten polymetallic deposit, eastern China: Deciphering the source of a skarn tungsten polymetallic deposit

The Donggushan tungsten polymetallic deposit is located near the northern margin of one of the most important ore deposit belts in China; the Middle - Lower Yangtze Metallogenic Belt (MLYB). The source and genesis of mineralization in the Donggushan deposit is poorly understood and is investigated using pyrite textures and geochemistry. Two types of pyrite and two subtypes were recognized, based on the location within the ore body, mineral assemblages, textures and geochemistry. Pyrite 1a occurs in the cores of pyrite crystals in the tungsten orebody, at depth within the deposit, near the intrusive rocks. It is characterized by high Ni and low contents of other trace elements and is overgrown by Py1b which has low Ni and higher trace elements. Pyrite 2a is characterized by moderate As and higher trace elements than those in Pyrite 1. It occurs in the cores of pyrite crystals in the shallow zinc-lead orebody. This pyrite is overgrown by Pyrite 2b characterized by higher trace elements. The trace elements, textures and inclusions in these pyrites suggest a progressive decrease in temperature, with Pyrite 1a forming at 350 °C through to Pyrite 2b forming at < 250 °C. The Pb isotopic compositions in the pyrites indicate that Pb in the deep tungsten ore body was derived from Yangtze upper crust (Dongling basement) but that Pb in the shallower ore body was sourced from the Dabie Orogen lower crust. The data supports a model whereby intra-continental subduction was the main geodynamic process controlling the mineralization of the Donggushan deposit.

The carbon state in dilute germanium carbides

Conduction and valence band states for the highly mismatched alloy (HMA) Ge:C are projected onto Ge crystal states, Ge vacancy states, and Ge/C atomic orbitals, revealing that substitutional carbon not only creates a direct bandgap but also the new conduction band is optically active. Overlap integrals of the new Ge:C conduction band state with states from unperturbed Ge show that the new band cannot be attributed to any single Ge band but is a mixture of multiple Ge states. The Ge Γ conduction band valley state plays the largest single role, but L and X valley states collectively contribute a larger share than Γ due to the multiplicity of degenerate states. C sites structurally resemble uncharged vacancies in the Ge lattice, similar to Hjalmarson's model for other HMAs. C also perturbs the entire Ge band structure even at the deepest crystal core energy levels, particularly if staggered supercells are used to mimic a disordered alloy. Projection onto atomic sites shows a relatively weak localization compared with other HMAs, but it does show a strong anisotropy in probability distribution. L-valley conduction band states in Ge contribute to the conduction band minimum in Ge:C, but the optical transition strength in Ge:C remains within a factor of 2 of the direct gap transition in Ge.

Silicon redistribution, acid site loss and the formation of a core–shell texture upon steaming SAPO-34 and their impact on catalytic performance in the Methanol-to-Olefins (MTO) reaction

SAPO-34 is a commercially-implemented silicoaluminophosphate catalyst for selective high yield production of ethene and propene from methanol, but high temperature regeneration in the presence of steam leads to its deactivation. A comprehensive investigation of the effect of prolonged hydrothermal treatment on the structure and properties of SAPO-34 explains the changes in its catalytic methanol-to-olefins (MTO) performance. Microcrystalline powdered SAPO-34 (ca. 3 µm crystals, Al17.1P15.6Si3.3O72) and two batches of larger single crystals of SAPO-34 of different Si concentration (20–100 µm; Al17.3P14.7Si4.0O72 and Al17.7P12.3Si5.9O72) were steamed (pH2O = 0.95 atm) at 873–1023 K for up to 240 h. The acidity (NH3-TPD), crystallinity (PXRD), framework cation environment (solid-state 27Al, 29Si and 31P MAS NMR) and porosity were followed for all materials; larger crystals were amenable to single crystal X-ray diffraction, FIB-SEM and synchrotron IR microspectroscopy, including operando study during methanol and dimethyl ether conversions. Some level of steaming improved the lifetime of all SAPO-34 materials in MTO catalysis without affecting their olefin selectivity, although more severe conditions led to the formation of core–shell structures, microporosity loss and eventually at 1023 K, recrystallization to a dense phase. All these irreversible changes occurred faster in crystals with higher Si contents. The initial increase in catalytic lifetime results from an activated reduction in acid site density (Eact = 146(18) kJ mol−1), a result of redistribution of Si within the SAPO framework without porosity loss. Operando IR with online product analysis during methanol conversion suggests similar reaction pathways in calcined and steamed crystals, but with greatly reduced methoxy group densities in the latter. The gradual development of optically dark crystal cores upon progressive steaming was shown by FIB-SEM to be due to the formation of regions with meso- and macropores, and these were shown by IR mapping to possess low hydroxyl densities.

Composition and genesis of albitite-hosted antecrystic pyrochlore from the Sevattur carbonatite complex, India

AbstractThe Neoproterozoic Sevattur complex is composed essentially of calcite and dolomite carbonatites together with pyroxenites and diverse syenites. This work reports the compositions and paragenesis of different pyrochlore generations hosted by albitite veins in this complex. The pyrochlore are distinctive, being exceptionally rich in uranium (26 to 36 wt.% UO2). Five types of pyrochlore (Pcl-I to Pcl-V) are recognised on the basis of composition and texture. With the exception of Pcl-V, the majority of the pyrochlore (Pcl-II to Pcl-IV) are surrounded by a thick orbicular mantle of Ba-rich potassium feldspar. This mantle around Pcl-V is partially-broken. Pcl-I is restricted to the cores of crystals, and associated with Pcl-II and -III and is relatively rich in Nb (0.53–0.62 apfu) together with more A-site vacancies (0.37–0.71 apfu) compared to Pcl-II to Pcl-IV. Other pyrochlore (Pcl-II to Pcl-IV) are characterised by elevated Ca and Ti compared to Pcl-I, which are related to the (3Nb5+ + Na+ → 3Ti4+ + U4+) and (2Nb5+ → 2Ti4+ + Ca2+) substitutions, respectively. These substitutions represent replacement of Pcl-II to Pcl-IV. Alteration and Ba-enrichment in all the pyrochlore are marked by interaction with an externally-derived Ba-rich hydrothermal fluid following the (2Nb5+ → 2Ti4+ + Ba2+) substitution. This substitution, coupled with extensive metamictisation leads to the formation of Ba-rich (15.9–16.3 wt.% BaO) patchy-zoned Pcl-V. The orbicular mantles around Pcl-I to Pcl-IV have prevented extensive metamictisation and extensive secondary alteration compared to Pcl-V, where mantling is partially disrupted. The compositional and textural variation suggests that Pcl-II to Pcl-IV form by nucleation on Pcl-I, and are transported subsequently as antecrysts in the host albitite.

Performance of Vibration Power Generators Using Single Crystal and Polycrystal Magnetic Cores of Fe–Ga Alloys

The performance of a vibration power generator using a single crystal core of Fe–Ga alloy was compared with that of a generator using a Fe–Ga alloy polycrystal core with a similar Ga concentration. When the generator using the polycrystal core was forcibly vibrated by 1-G acceleration, the vibration frequency dependence of the open-circuit voltage showed a peak with a maximum value of about 0.14 V at the first resonance frequency due to the inverse magnetostrictive effect. On the other hand, the generator using a single crystal core with a &lt;100&gt; direction parallel to the external stress direction exhibited a maximum value of about 0.26 V, about two-times larger than that of the device using the polycrystal core. Consequently, a vibration energy generator using a single crystal core of Fe–Ga alloy has advantages in performance over a generator using a polycrystal core.

Shape control of cathodized germanium oxide nanoparticles

In this paper, hexagonal germanium dioxide (GeO2) nanostructures with different morphologies and sizes were successfully synthesized by a simple and fast electrodeposition method. We investigated the electrochemical growth mechanism and the structural and optical properties of the products through Fourier transform infrared spectroscopy (FTIR), dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and cathodoluminescence (CL). The results reveal that the electrodeposited GeO2 nanostructures are pure, dense, and highly crystalline. The XRD analyses indicate that the resulting GeO2 crystals only show peaks related to the α-quartz structure. CL measurements exhibit strong blue and green light emissions related to oxygen vacancies in the core of the GeO2 crystals. The resulting nanostructures may have potential application in integrated optical devices in the future.

Potassium-Induced Passivation of Deep Traps in Bismuth-Doped Hybrid Lead Bromide Perovskite Nanocrystals: Massive Amplification of Photoluminescence Quantum Yield.

The low photoluminescence quantum yield of Bi3+-doped lead halide perovskite nanocrystals (NCs) is a big challenge to the scientific community. This makes them a weak candidate in the optoelectronics field in spite of their better stability than the pure lead analogue. Herein, the reason behind this reduction of quantum yield in hybrid mixed lead-bismuth bromide (MPBBr) NC is investigated and proposed to be due to ultrafast trapping transfer in the core of the NC, and not due to the surface trap states. Further, we have successfully boosted the quantum yield of MPBBr NC from 9% to 64% by passivating the deep traps within the crystal core by monovalent potassium ion doping. The stability of the developed Bi3+/K+-doped lead halide perovskite NC was found to be extremely high in atmospheric conditions, and this property is sustained up to 100 °C.

Morphology and Genesis of Ballas and Ballas-Like Diamonds

Ballas diamond is a rare form of the polycrystalline radial aggregate of diamonds with diverse internal structures. The morphological features of ballas diamonds have experienced repeated revision. The need that this paper presents for development of a crystal-genetic classification was determined by a rich variety of combined and transitional forms of ballas-like diamonds, which include aggregates, crystals, and intergrowths. The new crystal-genetic classification combines already-known and new morphological types of ballas as well as ballas-like diamonds discovered in the placers of Yakutia, the Urals, and Brazil. The ballas-like diamond forms include spherocrystals, aggregates with a single crystal core, split crystals, radial multiple twin intergrowths, and globular crystals. The crystal genetic scheme of the evolution of ballas and ballas-like diamonds is a sequence of the morphological types arranged in accordance with the conventional model of the dependence of the mechanism and diamond growth from carbon supersaturation developed by I. Sunagawa. The evolution of the growth forms of ballas and ballas-like diamonds was tracked based on the macrozonal structure of diamonds varying from a flat-faced octahedron to a fibrous cuboid with its transition forms to the radiating crystal aggregates. The morphological diversity of the ballas-like diamonds depends on the level of supersaturation, and abrupt changes of the level of supersaturation engender abrupt changes in a mechanism of crystal growth. The change in the rate of growth under the influence of adsorption and absorption of the mechanic impurities accompanied the sudden appearance of the autodeformation defects in the form of splitting and multiple radial twinning of crystals. The spherical shape of Yakutia ballas-like diamonds is due to the volumetric dissolution that results in the curved-face crystals of the “Urals” or “Brazilian” type associated with ballas diamonds in placers.

Operando Bragg Coherent Diffraction Imaging of LiNi0.8Mn0.1Co0.1O2 Primary Particles within Commercially Printed NMC811 Electrode Sheets.

Due to complex degradation mechanisms, disparities between the theoretical and practical capacities of lithium-ion battery cathode materials persist. Specifically, Ni-rich chemistries such as LiNi0.8Mn0.1Co0.1O2 (or NMC811) are one of the most promising choices for automotive applications; however, they continue to suffer severe degradation during operation that is poorly understood, thus challenging to mitigate. Here we use operando Bragg coherent diffraction imaging for 4D analysis of these mechanisms by inspecting the individual crystals within primary particles at various states of charge (SoC). Although some crystals were relatively homogeneous, we consistently observed non-uniform distributions of inter- and intracrystal strain at all measured SoC. Pristine structures may already possess heterogeneities capable of triggering crystal splitting and subsequently particle cracking. During low-voltage charging (2.7-3.5 V), crystal splitting may still occur even during minimal bulk deintercalation activity; and during discharging, rotational effects within parallel domains appear to be the precursor for the nucleation of screw dislocations at the crystal core. Ultimately, this discovery of the central role of crystal grain splitting in the charge/discharge dynamics may have ramifications across length scales that affect macroscopic performance loss during real-world battery operation.

A Co3O4/C Composite for use as a High‐Performance Lithium‐Ion Battery Anode

AbstractDue to advantages such as low environmental impact, low price, and high theoretical specific capacity, Co3O4 has been widely studied. However, its low conductivity and volume expansion during the charging and discharging processes caused pulverization and agglomeration ultimately leads to a rapid decline in battery capacity during the cycle. The creation of nano structured composite of carbon materials and Co3O4 can be used to form a highly conductive matrix that improves the electronic conductivity, and improves the dispersion of Co3O4 to reduce agglomeration and volume expansion. In this work, the rigid conjugated plane structure of 1,10‐phenanthroline was selected to coordinated with cobalt nitrate to form a precursor complex. After heating, the crystal core of Co3O4 becomes more uniform in size with a more regular geometry. Additionally, a calcining temperature of 350 °C was shown to result in an optimal amount of carbon residue that improved electronic conductivity of the whole composite while not excessively hindering lithium‐ion transport. As a result, these properties improved the electron conductivity and protect the crystals from damage caused by volume change during charge and discharge to a certain extent, thus contributing to improved electrochemical performance.

Photonic crystal waveguide for second harmonic generation: exact solution

We provide the exact solution of the dispersion equation for a waveguided semiconductor structure with a photonic crystal core that provides the efficient second harmonic generation in the visible range. The comparison of the results with an approximate solution shows good agreement.

Rib Waveguide Based Liquid Crystal EO Switch

We report electrically re-configurable liquid crystal core rib waveguide based electro-optic switch. It is proposed to use single side anchored in-plane switching (IPS) configuration for optical switching in view of its low threshold voltage and low switching voltage in comparison to that in a double-side anchored LC waveguide switch. Further, the proposed LC waveguide based switch has better response time than that in a double side anchored configuration at operating voltage close to threshold voltage of a double side anchored. The device has been realized on a BK7 glass substrate using E7 LC. We also show wavelength re-configurability of the switch over a wide wavelength range (1 - 3 μm) by externally applied voltage. Proposed work would be useful for optical signal processing on integrated optic platform.

Synthesis and properties of 5,6-dihydro-4H-cyclopenta[b]thiophene-based nematic liquid crystals: A new access to mesogens with high birefringence and large dielectric anisotropy

A novel liquid crystal core unit 5,6-dihydro-4H-cyclopenta[b]thiophene was designed and synthesized in four steps and three mesogens containing terminal cyano group were then obtained. The effects of this skeleton on the mesophase and physical properties of liquid crystals were then investigated by compared with two series of reference compounds based on 1,4-disubstituted phenylene and disubstituted phenylcyclohexane and found this unit can benefit the formation of the nematic phase. Besides, both the birefringence (Δn) and dielectric anisotropy (Δε) values were increased after the introduction of this core unit. Density function theory calculations suggested that the combination of thiophene and cyclopentane had increased the height/width ratio and linearity of the mesogens which can stabilise the liquid crystal phase. Five different liquid crystals based on this new core were synthesized at last to further illustrate the usefulness of this core in constructing high birefringence and large dielectric anisotropy liquid crystals with wide nematic phase interval.