High Rate and Long Cycle Life of a CNT/rGO/Si Nanoparticle Composite Anode for Lithium‐Ion Batteries

Si nanoparticle (Si‐NP) composite anode with high rate and long cycle life is an attractive anode material for lithium‐ion battery (LIB) in hybrid electric vehicle (HEV)/pure electric vehicle (PEV). In this work, a carbon nanotube (CNT)/reduced graphene oxide (rGO)/Si nanoparticle composite with alternated structure as Li‐ion battery anode is prepared. In this structure, rGO completely wraps the entire Si/CNT networks by different layers and CNT networks provide fast electron transport pathways with reduced solid‐state diffusion, so that the stable solid‐electrolyte interphase layer can form on the whole surface of the matrix instead of on single Si nanoparticle, which ensure the high cycle stability to achieve the excellent cycle performance. As a result, the CNT/rGO/Si‐NP anode exhibits high performances with long cycle life (≈455 mAh g^?1 at 15 A g^?1 after 2000 cycles), high specific charge capacity (≈2250 mAh g^?1 at 0.2 A g^?1, ≈650 mAh g^?1 at 15 A g^?1), and fast charge/discharge rates (up to 16 A g^?1). This nanostructure anode with facile and low‐cost synthesis method, as well as excellent electrochemical performances, makes it attractive for the long life cycles at high rate of the next generation LIB applications in HEV/PEV.     

Co3O4 Hollow Nanoparticles and Co Organic Complexes Highly Dispersed on N‐Doped Graphene: An Efficient Cathode Catalyst for Li‐O2 Batteries

Rechargeable Li‐O₂ batteries are promising candidates for electric vehicles due to their high energy density. However, the current development of Li‐O₂ batteries demands highly efficient air cathode catalysts for high capacity, good rate capability, and long cycle life. In this work, a hydrothermal‐calcination method is presented to prepare a composite of Co₃O₄ hollow nanoparticles and Co organic complexes highly dispersed on N‐doped graphene (Co–NG), which acts as a bifunctional air cathode catalyst to optimize the electrochemical performances of Li‐O₂ batteries. Co–NG exhibits an outstanding initial discharge capacity up to 19 133 mAh g^?1 at a current density of 200 mA g^?1. In addition, the batteries could sustain 71 cycles at a cutoff capacity of 1000 mAh g^?1 with low overpotentials at the current density of 200 mA g^?1. Co–NG composites are attractive as air cathode catalysts for rechargeable Li‐O₂ batteries.     

Laser crystals and ceramics: recent advances

After a brief examination of known insulating laser crystals and the stimulated emission channels of their generating activator ions, this article reviews recent advances in the development of novel lasing crystals and ceramics, as well as inorganic and organic nonlinear‐laser crystals for χ⁽³⁾ and cascaded χ⁽³⁾ ↔ χ⁽²⁾ frequency converters. Several new modern attractive technologies in the physics and techniques of crystalline lasers are also discussed.     

Finite‐element modelling of multilayer X‐ray optics

Multilayer optical elements for hard X‐rays are an attractive alternative to crystals whenever high photon flux and moderate energy resolution are required. Prediction of the temperature, strain and stress distribution in the multilayer optics is essential in designing the cooling scheme and optimizing geometrical parameters for multilayer optics. The finite‐element analysis (FEA) model of the multilayer optics is a well established tool for doing so. Multilayers used in X‐ray optics typically consist of hundreds of periods of two types of materials. The thickness of one period is a few nanometers. Most multilayers are coated on silicon substrates of typical size 60 mm × 60 mm × 100–300 mm. The high aspect ratio between the size of the optics and the thickness of the multilayer (10⁷) can lead to a huge number of elements for the finite‐element model. For instance, meshing by the size of the layers will require more than 10¹⁶ elements, which is an impossible task for present‐day computers. Conversely, meshing by the size of the substrate will produce a too high element shape ratio (element geometry width/height > 10⁶), which causes low solution accuracy; and the number of elements is still very large (10⁶). In this work, by use of ANSYS layer‐functioned elements, a thermal‐structural FEA model has been implemented for multilayer X‐ray optics. The possible number of layers that can be computed by presently available computers is increased considerably.     

The electric field of an electron in an electron–hole plasma with degenerate electrons: Possibility of formation of a superconductivity state

We consider the possibility of the formation of a superconductivity state either in a semiconductor or in an electron–hole plasma with degenerate electrons due to the attractive forces between the electrons as a result of the exchange effects through the electron–hole sound wave by an analogy to the phonon waves in a solid state. We have determined an interaction potential between two electrons in a degenerate electron–hole plasma. The potential appears to be attractive at distances much larger than the Debye radius and decreases as 1/r³. We discuss the conditions in which the bound electron state, the so‐called “Cooper Pair,” in a such field can be formed.     

Lithium Ferrites@Polydopamine Core–Shell Nanoparticles as a New Robust Negative Electrode for Advanced Asymmetric Supercapacitors

Spinel ferrites hold great promise as attractive electrode materials for high‐performance supercapacitors owing to their multiple valence states and abundant choice of metal cation. However, the main bottleneck for most of the currently reported spinel ferrite‐based electrodes is relatively low specific capacitance. Herein, a new kind of lithium ferrites (Li_0.5Fe_2.5O₄, LFO)@polydopamine (PDA) (denoted as LFO@PDA) core–shell nanoparticles with extraordinary capacitive performance as negative electrodes for aqueous asymmetric supercapacitors (ASCs) are reported first. Taking advantage of increased active sites, improved conductivity, enhanced hydrophilicity, and good strain accommodation in terms of the interesting core–shell architecture and PDA shell, the as‐obtained LFO@PDA electrode reaches a remarkable capacitance of 276.4 F g⁻¹ and prominent durability (no any capacitance loss after 15 000 cycles). Moreover, a robust aqueous 1.8 V‐ASC device with a preferable energy density of 33.9 Wh kg⁻¹ is also achieved based on the LFO@PDA electrode as negative electrode.     

Shape‐ and Trap‐Controlled Nanocrystals for Giant‐Performance Improvement of All‐Inorganic Perovskite Photodetectors

In the last few years, all‐inorganic perovskite CsPbBr₃ nanocrystals (NCs) have attracted tremendous attention for its high carrier mobility, long carrier diffusion length, excellent visible light absorption, and more importantly superior air stability. In fact, photodetectors (PDs) are designed and fabricated using the CsPbBr₃ NCs with very high performance. Herein, by optimizing the NC shape, size, and surface passivation, the CsPbBr₃ PDs are developed with an even higher performance. It is found that the PDs based on CsPbBr₃ nanoribbons show the best photoresponse among all common NC structures synthesized. Moreover, it is found that 6,6‐phenyl‐C61‐butyric acid ethyl ester can be used to passivate defects on the CsPbBr₃ nanoribbon surface and shows the charge transfer. As a result, the device displays superior photoresponsivity (R = 18.4 A W⁻¹), excellent signal‐to‐noise ratio, as high as 10⁴, and a very sharp rise/decay time (8.7/3.5 ms). The method demonstrated may offer an attractive strategy to improve sensitivity for all‐inorganic perovskite PDs in general.     

Raman spectroscopy of bromine chains inside the one‐dimensional channels of AlPO4‐5 single crystals

Raman spectroscopy of the one‐dimensional atomic or molecular chains, which are the attractive building blocks of advanced nanoscale materials, is crucial in understanding the physical properties of the one‐dimensional atomic or molecular chains. Here, we introduce the bromine into the one‐dimensional channels of AlPO₄‐5 single crystals through a physical vapor diffusion method. Raman spectroscopy indicates that the confined bromine structures mainly exist as (Br₂)_n chains, individual Br₂ molecules, and a small amount of Br₃⁻ chains inside the channels of AlPO₄‐5 single crystals. Polarized Raman spectra demonstrate that the bromine molecular chains are approximately parallel to the channel direction of AlPO₄‐5 single crystals. Copyright © 2015 John Wiley & Sons, Ltd.     

A multi‐MHz single‐shot data acquisition scheme with high dynamic range: pump–probe X‐ray experiments at synchrotrons

The technical implementation of a multi‐MHz data acquisition scheme for laser–X‐ray pump–probe experiments with pulse limited temporal resolution (100 ps) is presented. Such techniques are very attractive to benefit from the high‐repetition rates of X‐ray pulses delivered from advanced synchrotron radiation sources. Exploiting a synchronized 3.9 MHz laser excitation source, experiments in 60‐bunch mode (7.8 MHz) at beamline P01 of the PETRA III storage ring are performed. Hereby molecular systems in liquid solutions are excited by the pulsed laser source and the total X‐ray fluorescence yield (TFY) from the sample is recorded using silicon avalanche photodiode detectors (APDs). The subsequent digitizer card samples the APD signal traces in 0.5 ns steps with 12‐bit resolution. These traces are then processed to deliver an integrated value for each recorded single X‐ray pulse intensity and sorted into bins according to whether the laser excited the sample or not. For each subgroup the recorded single‐shot values are averaged over ～10⁷ pulses to deliver a mean TFY value with its standard error for each data point, e.g. at a given X‐ray probe energy. The sensitivity reaches down to the shot‐noise limit, and signal‐to‐noise ratios approaching 1000 are achievable in only a few seconds collection time per data point. The dynamic range covers 100 photons pulse^?1 and is only technically limited by the utilized APD.     

Polymeric Micelles Employing Platinum(II) Linker for the Delivery of the Kinase Inhibitor Dactolisib

Polymeric micelles are attractive nanocarriers for hydrophobic drug molecules such as the kinase inhibitor dactolisib. Two different poly(ethylene glycol)–poly(acrylic acid) (PEG‐b‐PAA) block‐copolymers are synthesized, PEG(5400)‐b‐PAA(2000) and PEG(10000)‐b‐PAA(3700), respectively. Polymeric micelles are formed by self‐assembly once dactolisib is conjugated via the ethylenediamine platinum(II) linker (Lx) to the PAA block of the block copolymers. Dactolisib micelles with dactolisib loading content of 17% w/w show good colloidal stability and display sustained release of Lx‐dactolisib over 96 h in PBS at 37 °C, while media containing reagents that compete for platinum coordination (e.g., glutathione (GSH) or dithiothreitol (DTT)) effectuate release of the parent inhibitor dactolisib at similar release rates. Dactolisib/lissamine‐loaded micelles are internalized by human breast adenocarcinoma cells (MCF‐7) in a dose and time‐dependent manner as demonstrated by confocal microscopy. Dactolisib‐loaded micelles inhibit the PI3K/mTOR signaling pathway at low concentrations (400 × 10^?9 m ) and exhibit potent cytotoxicity against MCF‐7 cells with IC₅₀ values of 462 ± 46 and 755 ± 75 × 10^?9 m for micelles with either short or longer PEG‐b‐PAA block lengths. In conclusion, dactolisib loaded PEG‐b‐PAA micelles are successfully prepared and hold potential for nanomedicine‐based tumor delivery of dactolisib.     

Observation of stimulated Raman scattering in polar tetragonal crystals of barium antimony tartrate trihydrate,Ba[Sb2((+)C4H2O6)2]·3H2O

The non‐centrosymmetric polar tetragonal (P 4₁) barium antimony tartrate trihydrate, Ba[Sb₂((+)C₄H₂O₆)₂]·3H₂O, was found to be an attractive novel semi‐organic crystal manifesting numerous χ ⁽²⁾‐ and χ ⁽³⁾‐nonlinear optical interactions. In particular, with picosecond single‐ and dual‐wavelength pumping SHG and THG via cascaded parametric four‐wave processes were observed. High‐order Stokes and anti‐Stokes lasing related to two SRS‐promoting vibration modes of the crystal, with ω_SRS1 ≈ 575 cm^?1 and ω_SRS2 ≈ 2940 cm^?1, takes place. Basing on a spontaneous Raman investigation an assignment of the two SRS‐active vibration modes is discussed.

     

A comment on the common one-dimensional derivation of the van der Waals forces

In many physical text-books a simple one-dimensional model is used to derive the characteristic 1/R ⁷-dependence of the attractive van der Waals forces. We show that this calculation is wrong. The long range forces in this simple model are not attractive but repulsive proportional to 1/R ⁶. Only a three-dimensional calculation yields the correct behavior.     

Collision-energy-resolved Penning ionization electron spectroscopy of styrene, 2-vinylpyridine, and 4-vinylpyridine with He*(23S) metastable atoms

Collisional ionization of styrene (phenylethylene), 2-vinylpyridine, and 4-vinylpyridine with metastable He*(2³S) atoms were studied by means of collision-energy/electron-energy resolved two-dimensional Penning ionization electron spectroscopy. Collision energy dependence of partial ionization cross-sections, which reflects the anisotropic interactions between a He*(2³S) atom and the target molecules, indicates that attractive interaction for the out-of-plane access of a He*(2³S) atom to phenyl group is stronger than that for the out-of-plane access to vinyl group. Moreover, it was found for vinylpyridines that the attractive interaction around π electrons became weaker than that for styrene, and that the attractive interaction for the in-plane access to the nitrogen atom is stronger than that for out-of-plane π-directions. However, in 2-vinylpyridine, the hydrogen atom of vinyl group prevents a He*(2³S) atom from approaching to the nitrogen atom along in-plane directions, and thus the attractive interactions around the nitrogen atom were shielded by the vinyl group. The experimentally observed anisotropic interactions were qualitatively supported with ab initio model interaction potential calculations between a Li (He*(2³S)) atom and the target molecule. Concerning with electronic structures of investigated molecules, the assignment of Penning ionization electron spectrum for 4-vinylpyridine was discussed on the basis of different behavior of collision-energy dependence of partial ionization cross-sections, and the satellite ionization band in Penning ionization electron spectra was also reported for styrene.     

Surface,micellar, and thermodynamic properties of antidepressant drug nortriptyline hydrochloride with TX‐114 in aqueous/urea solutions

This paper deals with a comprehensive study of the mixed micellization and adsorption behavior of mixed systems enclosing an amphiphilic antidepressant drug nortriptyline hydrochloride (NOT) and Triton X‐114 (TX‐114) (nonionic surfactant) in aqueous/urea (500 mmol·kg^?1 and 1000 mmol·kg^?1) solutions by tensiometric method. The NOT is used for the cure of depression. For comparison purpose cmc value of pure drug NOT was also evaluated by conductimetric technique. Different theoretical models like Clint, Rubingh, and Rosen were used to get information about the nature of interaction between the components in bulk and at the interface. Because of the occurrence of urea increase in the surface charge of the micelles was obtained resulting a delay of the micelles formation. The cmc values of the mixed systems of NOT and TX‐114 were found to be in between the cmc values of pure components, which signify nonideal mixed system having attractive interactions in the absence and presence of urea. Various parameters such as micellar mole fractions of TX‐114 (X₁^m, X₁^σ) in solution and at interface, interaction parameter (β^m/β^σ) in solution and at interface, and activity coefficient in solution and at interface were evaluated and discussed using Rubingh's and Rosen's models. Surface excess (Γ_max) increases that means minimum area per head group (A_min) decreases as mole fraction (α₁) of TX‐114 increases in the absence/presence of urea. Different thermodynamic parameters have been calculated and discussed. The ?G⁰_m values achieved are all negative both in the absence and occurrence of urea.     

Ultra‐large effective‐area,higher‐order mode fibers: a new strategy for high‐power lasers

This paper describes the physics and properties of a novel optical fiber that would be attractive for building high‐power fiber lasers and amplifiers. Instead of propagating light in the fundamental, Gaussian‐shaped mode, we describe a fiber in which the signal is forced to travel in a single, desired higher order mode (HOM). This provides for several advantages over the conventional approach, ranging from significantly higher ability to scale mode areas (and hence laser powers) to managing dispersion for ultra‐short pulses – a capability that is practically nonexistent in conventional fibers. Particularly interesting is the fact that this approach challenges conventional wisdom, and demonstrates that for applications requiring meter‐length fibers (as in high‐power lasers), signal stability actually increases with mode order. Using this approach, we demonstrate mode areas exceeding 3200 μm², and propagate signals with negligible mode distortions over up to 50‐meter lengths. We describe several pulse propagation experiments in which we test the nonlinear response of this fiber platform, ranging from managing dispersive effects in femtosecond pulse systems, to reducing Brillouin scattering impairments in systems operating with the nanosecond pulses.     

Electronic absorption spectrum of CO+ in an ion beam

The He+He⁺¹ interactions have been studied, as a function of the internuclear separation R, in terms of the electronic forces acting on the nuclei and the change in the charge distribution. The analysis reveals that at large R the atomic densities are polarized inwards, causing an attractive force on each nucleus, while at small R the difference in the nature of the interactions in the ²Σ_u and ²Σ_g systems is noted. It is seen that the He+He⁺¹ (²Σ_u) interaction is less attractive than the He⁺¹+He⁺¹ interaction at lower values of R.     

Diode laser based light sources for biomedical applications

Diode lasers are by far the most efficient lasers currently available. With the ever‐continuing improvement in diode laser technology, this type of laser has become increasingly attractive for a wide range of biomedical applications. Compared to the characteristics of competing laser systems, diode lasers simultaneously offer tunability, high‐power emission and compact size at fairly low cost. Therefore, diode lasers are increasingly preferred in important applications, such as photocoagulation, optical coherence tomography, diffuse optical imaging, fluorescence lifetime imaging, and terahertz imaging. This review provides an overview of the latest development of diode laser technology and systems and their use within selected biomedical applications. 670 nm external cavity diode laser for Raman spectroscopy built on a 13 × 4 mm² microbench (Copyright FBH/Schurian.com ).     

Bose–Einstein condensation of lithium

7 Li has been studied in a magnetically trapped gas. Many-body quantum theory predicts that the occupation number of the condensate is limited to about 1400 atoms because of the effectively attractive interactions between ⁷Li atoms. Using a versitile phase-contrast imaging technique, we experimentally observe the condensate number to be consistent with this limit. We discuss our measurements, the current theoretical understanding of BEC in a gas with attractive interactions, and future experiments we hope to perform. Received: 4 June 1997     

Ab initio study of spectroscopic properties of RgCl (Rg=He,Ne, Ar,Kr) and their anions

Spectroscopic properties of HeCl, NeCl, ArCl, KrCl and their anions HeCl^?, NeCl^?, ArCl^? and KrCl^? in their ground state have been studied in detail using ab initio MP2, CCSD and CCSD(T) methods. These neutral molecules and their anions are weakly bound and their spectroscopic constants have been estimated using a method developed recently for calculating the spectroscopic constants of weakly bound molecule in Lennard–Jones potential. The net attractive force and the distance at which the net attractive force is greatest, have been calculated to get the physical picture. Most of the spectroscopic constants are first predicted. The calculated equilibrium bond length, dissociation energy and harmonic frequency agree very well with the experimental and theoretical values wherever available.     

Chemical‐assisted femtosecond laser writing of optical resonator arrays

The design of micro‐optical resonator arrays are introduced and tailored towards refractive index sensing applications, building on the previously unexplored benefits of open dielectric stacks. The resonant coupling of identical hollow cavities present strong and narrow spectral resonance bands beyond that available with a single Fabry Perot interferometer. Femtosecond laser irradiation with selective chemical etching is applied to precisely fabricate stacked and waveguide‐coupled open resonators into fused silica, taking advantage of small 12 nm rms surface roughness made available by the self‐alignment of nanograting planes. Refractive index sensing of methanol‐water solutions confirm a very attractive sensing resolution of 6.5 × 10⁻⁵ RIU. Such high finesse optical elements open a new realm of optofluidic sensing and integrated optical circuit concepts for detecting minute changes in sample properties against a control solution that may find importance in chemical and biological sensors, telecom sensing networks, biomedical probes, and low‐cost health care products.