Positive Charge Holes Revealed by Energy Band Theory in Multiphase Tix O2x-1 and Exploration of its Microscopic Electromagnetic Loss Mechanism.

Although numerous experimental investigations have been carried out on the problem of defect engineering in semiconductor absorbers, the relationship among charge carrier, defects, heterointerfaces, and electromagnetic (EM) wave absorption has not been established systematically. Herein, the new thermodynamic and kinetic control strategy is proposed to establish multiphase Tix O2 x -1 (1 ≤ x ≤ 6) through a hydrogenation calcination. The TiOC-900 composite shows the efficient EM wave absorption capability with a minimum reflection loss (RLmin ) of -69.6 dB at a thickness of 2.04 mm corresponding to an effective absorption bandwidth (EAB) of 4.0 GHz due to the holes induced conductance loss and heterointerfaces induced interfacial polarization. Benefiting from the controllable preparation of multiphase Tix O2 x -1 , a new pathway is proposed for designing high-efficiency EM wave absorbing semiconducting oxides. The validity of the method for adopting energy band theory to explore the underlying relations among charge carriers, defects, heterointerfaces, and EM properties in multiphase Tix O2 x -1 is demonstrated for the first time, which is of great importance in optimizing the EM wave absorption performance by electronic structure tailoring.

In-situ construction of Cr2O3@ATO hybrid pigment towards synergetic enhancement of visible light-infrared-radar compatible stealth.

Multiband compatible stealth engineering with controllable visible light-infrared (VIS-IR) features and radar wave absorption is urgently needed to improve the survivability of advanced military equipment. Cr2O3 has good visible light stealth performance under green background, but it is lack of IR and radar multi-band stealth properties. Herein, a core-shelled Cr2O3@stannic antimony oxide (ATO) structure was developed to enhance the IR-radar compatible stealth properties of Cr2O3 by in-situ precipitation method, concurrently maintaining its visible light stealth property. The morphology, conductivity, and infrared stealth properties of the Cr2O3@ATO hybrids were influenced by the calcination temperature, and the IR and radar stealth performance were tunable by ATO content. The lowest emissivity of Cr2O3@ATO pigments is 0.852, reduced by 10% than pure Cr2O3. The Cr2O3@ATO filled silicone resin coatings possessed good thermal stability and IR stealth stability. Benefiting from the enhanced interfacial polarization and conductive loss, the Cr2O3@ATO exhibited an effective absorption bandwidth of 2 GHz in the X band, with respect to pure Cr2O3 without radar absorption property. The Cr2O3@ATO structure opens an avenue for advanced VIS-IR-Radar compatible stealth materials.

Ratiometric detection of I- using a dysprosium-based metal-organic framework with a single emission center.

In this study, a dysprosium-based metal-organic framework (MOF) sensor (Dy-MOF) was developed for the ratiometric detection of I- in aqueous medium. Upon excitation at 230 nm, Dy-MOF shows two dominant emission bands at 464 nm and 574 nm assigned to (4F, 4D)5/2 → 6H9/2 + 6F11/2 and 4F9/2 → 6H13/2 transition of Dy3+, respectively, which have different sensitivities toward iodide ions. The introduction of I- slightly weakened the blue emission at 464 nm and significantly quenched the yellow emission at 574 nm. Thus, ratiometric sensing for iodide was realized using the yellow-to-blue intensity ratio of Dy3+. Dy-MOF exhibits superior sensing behavior towards I- with high selectivity, sensitivity and low detection limit (24 nM). This study also provides a strategy for the construction of a ratiometric sensor with dual-emission bands originating from only one emission center.

A crosslinked coral-like Co@CoO/RGO nanohybrid structure with good electromagnetic wave absorption performance.

The combination of magnetic and dielectric materials followed by appropriate structure design is an effective approach to achieve high electromagnetic wave absorption properties. Here, crosslinked Co@CoO/reduced graphene oxide nanohybrids (CCRGO) were fabricated via a simple three-step method. The experimental results show that compared with previous works, the as-prepared CCRGO nanohybrids achieve higher electromagnetic wave absorption and broader effective bandwidth at a lower filler loading. The electromagnetic parameters and electromagnetic wave absorption performance could be apparently adjusted by controlling the adding content of graphene oxide (GO) and the reduction temperature. Among a series of samples, CCRGO3-650 nanohybrid yields the best electromagnetic wave absorption performance benefiting from the proper GO addition and reduction temperature. At a filler loading of 20 wt%, the maximal reflection loss reaches to -64.67 dB at a thickness of 2.53 mm and the effective bandwidth below -10 dB covers the whole X band at a thickness of 2.51 mm. The good performance may be ascribed to the advantages of the dielectric and magnetic component as well as the special crosslinked structure, which triggers a synergistic absorption mechanism including multiple reflection/scattering, interface polarization, dipole polarization, conductive loss, eddy current loss, exchange resonance in the electromagnetic wave dissipation process. The good electromagnetic wave absorption performance affirms the potential application of CCRGO nanohybrids in the field of stealth materials.

A ratiometric luminescence sensing platform based on lanthanide-based silica nanoparticles for selective and sensitive detection of Fe3+ and Cu2+ ions.

Detection of Fe(III) and Cu(II) in water is highly desirable because their abnormal levels can cause serious harm to human health and environmental safety. In this work, a ratiometric luminescence sensing platform based on lanthanide-based silica nanoparticles was constructed for the detection of Fe3+ and Cu2+ ions. The terbium-silica nanoparticles (named SiO2@Tb) with dual-emission signals were successfully prepared by grafting Tb3+ ions onto trimellitic anhydride (TMA) functionalized silica nanospheres. It can serve as a ratiometric fluorescent probe for the detection of Fe3+ and Cu2+ ions in water with the green emission of Tb3+ ions as a response signal and the blue emission of silica nanospheres as the reference signal. Significantly, an easy-to-differentiate color change for visual detection was also realized. SiO2@Tb shows high sensitivity even in very low concentration regions towards the sensing of Fe3+ and Cu2+ with low detection limits of 0.75 µM and 0.91 µM, respectively. Moreover, the mechanism for the luminescence quenching of SiO2@Tb was systematically investigated, and was attributed to the synergetic effect of the absorption competition quenching (ACQ) mechanism and cation exchange. This study demonstrates that SiO2@Tb can be employed as a promising fluorescent probe for the detection of Fe3+ and Cu2+ ions, and the combination of lanthanide ions with silica nanoparticles is an effective strategy to construct a ratiometric fluorescent sensing platform for the determination of analytes in environmental detection.

Total Laparoscopic Resection of an Extrahepatic Mucinous Biliary Cystadenoma with Liver Involvement (with Video).

BACKGROUND: Intrahepatic mucinous biliary cystadenoma is rare, and extrahepatic MBC is even rarer. To our knowledge, total laparoscopic resection of an extrahepatic MBC that had extended intrahepatically has never been reported. PATIENTS AND METHODS: A 28-year-old female presented to our hospital with upper abdomen pain. Radiological investigations demonstrated a 7-cm multiloculated cystic lesion arising from the left hepatic bile duct extending to involve the extrahepatic biliary system down to and posterior to the back of the head of pancreas. The entire extrahepatic bile duct was involved, except for the gallbladder. Laparoscopic surgery was carried out using a five-port approach. A gourd-shaped well-defined multiloculated cyst was found extending from the extrahepatic biliary system proximally to involve the left hepatic duct intrahepatically. After cholecystectomy, the gourd-shaped cyst was opened at its narrowest part at the hepatic hilus to facilitate subsequent resectional surgery. The distal sac was dissected to the distal bile duct end at the duodenal wall and transected. The proximal sac was dissected and resected en bloc with the bifurcation of the right/left hepatic ducts, combined with left hepatectomy plus caudate lobectomy. The reconstruction was done by anastomosing the right anterior and posterior sectional bile ducts to a Roux-en-Y jejunal loop. Multiple intraoperative frozen sections demonstrated the lesion to be a benign MBC. RESULTS: The patient was discharged home 12 days after surgery. She was well on follow-up 24 months after surgery. CONCLUSION: Total laparoscopic resection is technically feasible to treat an extrahepatic MBC with intrahepatic extension.

Balancing Between Polarization and Conduction Loss toward Strong Electromagnetic Wave Absorption of Hard Carbon Particles with Morphology Heterogeneity.

The heterostructure and hierarchical morphology of carbonaceous absorbents play an important role in the construction of high-performance electromagnetic wave absorbing materials. Herein, novel micron-scale hard carbon particles with morphology heterogeneity were developed as lightweight superior electromagnetic wave absorbents via a facile and ecofriendly process. The as-prepared hard carbon particle composed of pseudographite and a highly disordered region shows a unique heterostructure. Concurrently, constructing a multilevel geometric shape and size can cause a decrease of the percolation threshold and an excellent balance between polarization and conduction loss, which enhances the electromagnetic wave absorption significantly. The composites (thickness d = 2.36 mm) filled with morphology-heterogeneity hard carbon particles (15 wt %) achieve an excellent electromagnetic wave absorption with a minimum reflection loss of -78.0 dB at 10.2 GHz and effective absorption bandwidth (<-10 dB) of 3.1 GHz (8.8-11.9 GHz). Compared to the traditional carbonaceous absorbents with complex microstructures and/or multiple chemical components, this work presents a feasible idea for the development of an efficient carbonaceous absorbent to realize practical applications.

Ag2Mo2O7: an oxide solid-state Ag+ electrolyte.

Ag2Mo2O7 powders and micro-crystals were prepared at 400 °C for 24 h and 500 °C for 6 h using solid-state reactions. The Ag2Mo2O7 samples crystalized in a triclinic P1̄ space group with the cell parameters a = 6.0972(1) Å, b = 7.5073(1) Å, c = 7.6779(2) Å, α = 110.43(1)°, ß = 93.17(1)°, γ = 113.51(1)°, and V = 294.17(1) Å3 from Rietveld refinements. Ag2Mo2O7 powder is homogeneous with size of 2-8 µm and the ceramic pellets are in good sintering conditions with a relative density ∼93%. The indirect band gaps E g(i) of Ag2Mo2O7 from reflectance measurements and DFT calculations are 2.63(1) and 1.80 eV. The vibrational modes of Ag2Mo2O7 were investigated by first-principles (DFT) calculations and Raman spectrum measurements with 24 of 33 predicted Raman modes recorded. According to DOS analyses, the valence bands (VB) of Ag2Mo2O7 are mainly constituted of O-2p and Ag-4d orbitals, while the conduction bands (CB) are mainly composed of Mo-4d and the O-2p orbitals. Regarding the impedance analysis, Ag2Mo2O7 is a silver oxide ion electrolyte with a conductivity of ∼5 × 10-4 S cm-1 at 450 °C. The carrier activation energy of Ag2Mo2O7 is 0.88(3) eV from the temperature dependent conductivity measurements.

The mechanism of starch granule reacted with OSA by phase transition catalyst in aqueous medium.

The reactivity of octenyl succinic anhydride (OSA) with starch by phase transition catalyst (PTC) was investigated. The effects of two types (quaternary ammonium salt and non-ionic surfactant) and concentrations of PTC on the degree of substitution (DS) and reaction efficiency (RE) of OS-starch were examined. In aqueous medium, the use of a PTC, polyoxyethylene lauryl ether (AEO) produced derivatives with higher DS than others. The DS of OS-starch reached 0.0195 with 0.1% AEO, significantly higher than that (0.0182) without the use of PTC. As the concentration of AEO increased, the DS of OS-starch did not increase. The structural of AEO was investigated by nuclear magnetic resonance (NMR) spectroscopy. Conductivity measurement and Fourier transform infrared (FT-IR) spectroscopy confirmed that AEO could form complexes with Na(+). The complex of AEO and Na(+) could combine with starch-O(-), it should be possible to improve the transport of anion starch-O(-) to the hydrophobic reagents.

Ionic liquids as solvents for dissolution of corn starch and homogeneous synthesis of fatty-acid starch esters without catalysts.

Ionic liquids (ILs) utilized for dispersing cellulose have gained increasing attention in recent years, but the number of the reports using ILs for starch is still limited. In this study, 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) and 1-ethyl-3-methlyimidazolium acetate ([EMIM]AC) were used to dispersing corn starch. Dimethyl sulfoxide (DMSO), a traditional organic solvent for starch, was added into [BMIM]Cl, and the mixture of [BMIM]Cl/DMSO was utilized for dispersing corn starch as well. Results showed that the starch granules dispersed in ILs was much smaller than native starch granules, and large starch aggregates were partially formed. Starch granules dispersed in [BMIM]Cl at 100 °C for 60 min remained less crystallinity than native starch granules, while it was disappeared when starch granules were dispersed in [EMIM]AC at 100 °C for 60 min. Homogenous synthesis of fatty-acid starch esters without catalysts in these ILs was also studied. The degree of substitution (DS) value of starch laurate was reached to 0.053, 0.068 and 0.100 in [BMIM]Cl, [EMIM]AC and the mixture of [BMIM]Cl/DMSO, respectively, at the reaction conditions of lauric acid/AGU molar ratio 1:5, temperature 120 °C at a reaction time of 3 h.

Application of functional CdS nanoparticles in determination of silver ion by resonance light-scattering technique.

Based on the strong enhancement effect of silver ion on resonance light-scattering intensity of functional CdS nanoparticles, a new direct quantitative determination method for silver ion was established. Under the optimum conditions, the response signal is linearly proportional to the concentration of silver ion. The linear range is 5.0x10(-9)-2.0x10(-6) mol L(-1). The proposed method was applied to determine silver ion in river water samples.

Comments on: A unified algorithm for principal and minor components extraction.

This letter points out that the unified algorithm given by Chen et al. (Chen, T., Amari, S., & Lin, Q. (1998). Neural Networks, 11, 385-390) is a direct generalization of our invariant-norm algorithm. However, this direct-generalized unified algorithm is not practical from the learning point of view as the involved computations are intensive. As a matter of fact, a more effective generalization is made available.

A Minor Component Analysis Algorithm.

The eigenvectors corresponding to the smallest eigenvalues of the autocorrelation matrix of the input signals are defined as the minor components, which play a very important role in many fields of adaptive signal processing such as spectral estimation, total least squares processing, eigen-based bearing estimation, digital beamforming, moving target indication, and clutter cancellation. This paper proposes a learning algorithm which extracts adaptively the minor component. We will use the Rayleigh quotient as an energy function and prove both analytically and by simulation results that the weight vector provided by the proposed algorithm is guaranteed to converge to the minor component of the input signals. Copyright 1997 Elsevier Science Ltd. All Rights Reserved.