Soft X-ray emission from a CO2 laser-heated Z-pinch plasma

We report results of soft X-ray measurements in which a high-power (10¹⁰–10¹¹ W/cm²) CO₂ laser was used to heat a near critical density (<10¹⁹ cm^–3) helium Z-pinch plasma. Frequency-integrated X-ray data show that the unheated Z-pinch plasma is Maxwellian with a temperature of about 30 eV. During laser heating, the X-ray emissions were enhanced over the unheated emissions. Analysis of the experimental X-ray spectra indicate that the low-energy portion of the X-ray emission spectrum (up to 600 eV) is enhanced over the baseline 30 eV Maxwellian emissions. This result is consistent with an inverse bremsstrahlung-modified distribution which results when the plasma heating rate is more rapid than the collisional thermalization rate. These results suggest that it may be possible to enhance the soft X-ray yield of a plasma lithographic source with laser heating.     

Natural Soft/Rigid Superlattices as Anodes for High-Performance Lithium-Ion Batteries

Volume expansion and poor conductivity are two major obstacles that hinder the pursuit of the lithium-ion batteries with long cycling life and high power density. Herein, we highlight a misfit compound PbNbS₃ with a soft/rigid superlattice structure, confirmed by scanning tunneling microscopy and electrochemical characterization, as a promising anode material for high performance lithium-ion batteries with optimized capacity, stability, and conductivity. The soft PbS sublayers primarily react with lithium, endowing capacity and preventing decomposition of the superlattice structure, while the rigid NbS₂ sublayers support the skeleton and enhance the migration of electrons and lithium ions, as a result leading to a specific capacity of 710 mAh g⁻¹ at 100 mA g⁻¹, which is 1.6 times of NbS₂ and 3.9 times of PbS. Our finding reveals the competitive strategy of soft/rigid structure in lithium-ion batteries and broadens the horizons of single-phase anode material design.     

Polymerization of the 12-methacryloyloxydodecanoic acid and a corresponding phospholipid in monolayers at the liquid/gas interfaces

The following surface-active monomers with methacrylic group at the end of hydrophobic tail: 12-methacryloyloxydodecanoic acid (12-MAODA) and 12-(methacryloyloxydodecanoyl)-glycerophosphatidylcholine 12-MAODPC) were synthesized and investigated. Both monomers are forming monolayers at the liquid/gas interfaces with liquid-expanded and liquid-condensed states at low and high surface pressures, respectively. These monomers have been polymerized in the monolayers just by soft UV-irradiation (254 nm). Dependences of polymerization rate vs. surface pressure for both monomers have maxima (3.33^*10⁻⁴ s⁻¹ for 12-MAODPC and 4.89^*10⁻⁴ s⁻¹ for 12-MAODA) at about 8–10 mN/m. The higher polymerization rate of 12-MAODA polymerization as compared to 12-MAODPC is due to the more dense packing of the acid molecules in monolayers as compared to the lipid. Areas per monomer unit in the obtained polymeric monolayers are much smaller than those for the monomer one. The collapse pressures increase after monomer polymerization that evidences the increase of the monolayer stability in case of polymer as compared to monomer.     

Syntheses and characterizations of soft‐segment ionic polyurethanes

Novel soft‐segment ionic polyurethane (linear and crosslinking) have been prepared based up on sodium sulfonate–side chains poly(ethylene oxide) (SPEO). SPEO was synthesized by grafting the sodium sulfonate onto the chain of poly(ethylene oxide) with molecular weights of 400, 600, 800, and 1000. The SPEO and the ionic polyurethane were characterized by elemental analysis, ¹H‐NMR, ¹³C‐NMR, gel permeation chromatography, and impedance analysis. The effect of plasticizer on the ionic conductivity of the polyurethane was also investigated. These solid polymer electrolytes possess a higher ionic conductivity (about 10⁻⁶ S/cm at room temperature) than the corresponding sulfonated hard‐segment polyurethane electrolytes. The presence of the hydroxyl group in the electrolyte tends to lower the ionic conductivity. Crosslinking of polyurethane results in the enhancement of the dimensional stability, while maintaining the same level of the ionic conductivity. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 837–845, 1999     

Multi-Electron Reactions Enabled by Anion-Based Redox Chemistry for High-Energy Multivalent Rechargeable Batteries

The development of multivalent metal (such as Mg and Ca) based battery systems is hindered by lack of suitable cathode chemistry that shows reversible multi-electron redox reactions. Cationic redox centres in the classical cathodes can only afford stepwise single-electron transfer, which are not ideal for multivalent-ion storage. The charge imbalance during multivalent ion insertion might lead to an additional kinetic barrier for ion mobility. Therefore, multivalent battery cathodes only exhibit slope-like voltage profiles with insertion/extraction redox of less than one electron. Taking VS₄ as a model material, reversible two-electron redox with cationic–anionic contributions is verified in both rechargeable Mg batteries (RMBs) and rechargeable Ca batteries (RCBs). The corresponding cells exhibit high capacities of >300 mAh g⁻¹ at a current density of 100 mA g⁻¹ in both RMBs and RCBs, resulting in a high energy density of >300 Wh kg⁻¹ for RMBs and >500 Wh kg⁻¹ for RCBs. Mechanistic studies reveal a unique redox activity mainly at anionic sulfides moieties and fast Mg²⁺ ion diffusion kinetics enabled by the soft structure and flexible electron configuration of VS₄.     

A Self-Assembled Unit Comprising 12 Squaraine Dyes Built Up from Two Star-Shaped Hexasquarainyl-Benzene Molecules

We describe the aggregate formation and optical properties of a star-shaped hexaarylbenzene with six squaraine chromophores (=hexasquarainyl benzene). Comprehensive concentration-dependence studies in acetone/CHCl₃ mixtures reveal a strong propensity to form discrete dimeric aggregates with a high binding constant in excess of 10⁶ m ⁻¹. In this context, a large hypsochromic shift of almost 2700 cm⁻¹ was found in the absorption spectrum, indicating H-type exciton coupling. The aggregate band is characterised by a very small band width of only 560 cm⁻¹, probably caused by exchange narrowing. Both experimental and computational methods were used to elucidate the supramolecular aggregate structure, which is assumed to consist of two stacked hexasquarainyl benzene monomers.     

Propeller-Shaped Semi-fused Porphyrin Trimers: Molecular-Symmetry-Dependent Chiroptical Response

Triple helicene-like semi-fused trimeric Ni^II porphyrins were constructed by alkyne trimerization of an ethynyl-substituted porphyrin and subsequent three-fold Grignard addition to the formyl groups and acid-catalyzed intramolecular cyclization. The presence of stereogenic sp³ carbons in the central bridge leads to small inter-porphyrin conjugative interactions as was revealed by electrochemical and optical properties. Two diastereomers with stable chiral conformations were optically resolved, and the separated enantiomers displayed considerably intense circular dichroism. Importantly, the chiroptical response of C₃-symmetric helical isomer (|Δϵ|=830 m ⁻¹ cm⁻¹) is 1.8 times amplified from that of C₁-symmetric one (|Δϵ|=470 m ⁻¹ cm⁻¹). The observed amplification has been interpreted in terms of different spatial arrangements of the three porphyrins.     

Ionic electro-active polymer actuator based on cobalt-containing nitrogen-doped carbon/conducting polymer soft electrode

Nanoscale cobalt-containing nitrogen-doped porous carbon (CoNC) materials were prepared by thermolysis of a zeolitic imidazolate framework (ZIF), ZIF-67, at different temperatures and their application for ionic electro-active polymer (EAP) actuator was evaluated. CoNC-700, which was obtained from ZIF-67 pyrolysis at 700 °C, exhibits specific surface area of 753.86 m² g⁻¹, pore volume of 0.5768 cm³ g⁻¹, and specific capacitance of 120.7 F∙g⁻¹. CoNC/conducting polymer soft electrode were fabricated by unitizing effective interaction of CoNC with poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). High-performance ionic actuators were developed for the first time using this CoNC/PEDOT:PSS soft electrode. The developed ionic EAP actuator exhibited large peak-to-peak displacement of 20.4 mm and high bending strain of 0.28% (3 V and 0.1 Hz). Therefore, ZIFs or metal organic frameworks (MOFs) can be applied to provide significant improvements in EAP actuators, which can play key roles as technological advances toward bioinspired actuating devices required for next-generation soft and wearable electronics.     

Hierarchical Hollow-Nanocube Ni−Co Skeleton@MoO3/MoS2 Hybrids for Improved-Performance Lithium-Ion Batteries

Improving the performance of anode materials for lithium-ion batteries (LIBs) is a hotly debated topic. Herein, hollow Ni−Co skeleton@MoS₂/MoO₃ nanocubes (NCM-NCs), with an average size of about 193 nm, have been synthesized through a facile hydrothermal reaction. Specifically, MoO₃/MoS₂ composites are grown on Ni−Co skeletons derived from nickel–cobalt Prussian blue analogue nanocubes (Ni−Co PBAs). The Ni−Co PBAs were synthesized through a precipitation method and utilized as self-templates that provided a larger specific surface area for the adhesion of MoO₃/MoS₂ composites. According to Raman spectroscopy results, as-obtained defect-rich MoS₂ is confirmed to be a metallic 1T-phase MoS₂. Furthermore, the average particle size of Ni−Co PBAs (≈43 nm) is only about one-tenth of the previously reported particle size (≈400 nm). If assessed as anodes of LIBs, the hollow NCM-NC hybrids deliver an excellent rate performance and superior cycling performance (with an initial discharge capacity of 1526.3 mAh g⁻¹ and up to 1720.6 mAh g⁻¹ after 317 cycles under a current density of 0.2 A g⁻¹). Meanwhile, ultralong cycling life is retained, even at high current densities (776.6 mAh g⁻¹ at 2 A g⁻¹ after 700 cycles and 584.8 mAh g⁻¹ at 5 A g⁻¹ after 800 cycles). Moreover, at a rate of 1 A g⁻¹, the average specific capacity is maintained at 661 mAh g⁻¹. Thus, the hierarchical hollow NCM-NC hybrids with excellent electrochemical performance are a promising anode material for LIBs.     

Fiber-optic evanescent wave fourier transform infrared (FEW-FTIR) spectroscopy of polymer surfaces and living tissue

The new method of fiber-optic evanescent wave Fourier transform infrared (FEW-FTIR) spectroscopy has been applied to studies of polymer surfaces and the diagnostics of normal, precancerous and cancerous tissue. This technique using optical fibers and fiber-optic sensors operating in the attenuated total reflection (ATR) mode in the mid-infrared (IR) region of the spectrum (850 – 1850 cm⁻¹) has found recently application in the area of tissue diagnostics. The method is suitable for noninvasive and rapid (seconds) direct measurements of the spectra of normal and pathological tissues in vitro, ex vivo, and in vivo. The FEW-FTIR technique is an ideal diagnostic tool for different types of soft, porous, foam, and rough polymer surfaces. Inhomogeneous coatings and defects on polymer surfaces as well as layer structures have also been detected by this method. It is convenient to apply this method to analyze large pieces of soft plastics and/or surfaces covered by plastics, since these types of surfaces are comparatively hard to analyze by traditional absorption spectroscopy. The FEW-FTIR technique is non-destructive, fast (15 seconds), and remote (up to a fiber length of 3m). In addition, it is sensitive enough to detect any changes in the vibrational spectra of a polymer surface, without heating and damaging it. The surfaces of polyethylene crumpled bags and rumpled films have been investigated in the range of 2000 – 1000 cm⁻¹. The distinct spectra of these surfaces as well as spectra of polytetrafluoroethylene have been recorded. The spectra of white and colored foams and different plastics have also been studied. Weak but distinct spectra have been recorded for carbon fibers (black, narrow fibers with a diameter of about 10 μm). Using the FEW-FTIR technique, measurements can be taken without preparing the sample. High quality spectra have also been obtained for the bulk and surfaces of apple, banana, grapefruit, and other food products. The method is expected to be further developed for geological and microelectronic applications.     

Novel Photobleachable Deep UV Resists Based on Single Component Nonchemically Amplified Resist System

Summary: Photobleachable deep UV resists were designed by introducing diazoketo groups in polymer side chains. The diazoketo groups undergo the Wolff rearrangement upon irradiation in the deep UV, affording ketenes that react with water to provide base‐soluble photoproducts. The polymers were synthesized by radical copolymerization of 2‐(2‐diazo‐3‐oxo‐butyryloxy)‐ethyl methacrylate, 2‐hydroxyethyl methacrylate, and γ‐butyrolacton‐2‐yl methacrylate. The single component resist showed 0.7 µm line and space patterns using a mercury‐xenon lamp in a contact printing mode.

Scanning electron micrograph of 0.7 µm line and space patterns printed with polymer B at a dose of 70 mJ · cm⁻².     

Mesostructured Dye‐Doped Titanium Dioxide for Micro‐Optoelectronic Applications

Optically transparent, mesostructured titanium dioxide thin films were fabricated using an amphiphilic poly(alkylene oxide) block copolymer template in combination with retarded hydrolysis of a titanium isopropoxide precursor. Prior to calcination, the films displayed a stable hexagonal mesophase and high refractive indices (1.5 to 1.6) relative to mesostructured silica (1.43). After calcination, the hexagonal mesophase was retained with surface areas >300 m² g^?1. The dye Rhodamine 6G (commonly used as a laser dye) was incorporated into the copolymer micelle during the templating process. In this way, novel dye‐doped mesostructured titanium dioxide films were synthesised. The copolymer not only directs the film structure, but also provides a solubilizing environment suitable for sustaining a high monomer‐to‐aggregate ratio at elevated dye concentrations. The dye‐doped films displayed optical thresholdlike behaviour characteristic of amplified spontaneous emission. Soft lithography was successfully applied to micropattern the dye‐doped films. These results pave the way for the fabrication and demonstration of novel microlaser structures and other active optical structures. This new, high‐refractive index, mesostructured, dye‐doped material could also find applications in areas such as optical coatings, displays and integrated photonic devices.     

Ion conduction in poly(crown ethers), polyglucosan gels and macroporous polyethylene films

Much work has been reported on ion conduction in solid solutions of salts dissolved in linear and comb-branched poly(ethylene oxide) analogues. There appears to be a limit to the conductivity levels achieved in such systems, and conductivity values rarely exceed σ ∼ 10⁻⁴ Scm⁻¹ at room temperature. To overcome this there has been a move towards more mobile plasticized systems and polymer gel electrolytes are receiving some attention. Gels prepared from N-methyl-2-pyrrolidinone/LiCl and polyglucosans such as cellulose and amylose have been studied and show some promise with ambient σ Ge; 10⁻⁴ Scm⁻¹. Macroporous polyethylene has also been used to support fluid polyethylene glycol/salt systems, but these only reached σ ≥ 10⁻⁵ Scm⁻¹ at ambient temperature. Comb-branch polymers with crown ethers provide systems with respectable room temperature conductivities of between 10⁻⁴ and 10⁻⁵ Scm⁻¹, but these might be improved if the crown ethers could be arranged in regular channels. Ways to achieve this are briefly discussed.     

Direct Synthesis of Nanosheet-Stacked Hierarchical “Honey Stick-like” MFI Zeolites by an Aromatic Heterocyclic Dual-Functional Organic Structure-Directing Agent

Soft template designing is the most promising strategy for the synthesis of zeolite nanosheets. MFI nanosheets directed by soft templates (containing long-chain alkyl groups or aromatic groups as hydrophobic component) can be found frequently; however, so far, MFI nanosheets synthesized by soft templates with aromatic heterocycle groups (e. g., s-triazine groups) are rare. Herein, a nanosheet-stacked hierarchical MFI zeolite (NSHM) has been synthesized by using a triply branched s-triazine-based surfactant as a bifunctional organic structure-directing agent. On the basis of a geometrical match relationship, a formation model has been proposed. Synthesized NSHM had abundant mesopores stacked by nanosheets and exhibited a high surface area (430 m² ⋅ g⁻¹). The 1 wt% Pd/NSHM attained a significant increase in yield of cyclohexanol/cyclohexanone mixture (from 66 to 85 %) in the oxidation of cyclohexane compared with Silicalite-1 and SBA-15 as supports.     

Study of the ν2 + ν3 infrared band of ONCl

Two hundred and sixty A type rovibrational lines of the ν₂ + ν₃ vibrational band of ¹⁶O¹⁴N³⁵Cl, around 925 cm⁻¹, have been assigned; a least-squares calculation with a r.m.s. deviation of 0.0006 cm⁻¹ has made it possible to measure several constants of the (011) vibrational level.     

Hydrogen/oxygen polymer electrolyte membrane fuel cells (PEMFCs) based on alkaline-doped polybenzimidazole (PBI)

When complexed with alkaline such as potassium hydroxide, sodium hydroxide or lithium hydroxide, films (40 μm thick) of polybenzimidazole (PBI) show conductivity in the 5 × 10⁻⁵–10⁻¹ S/cm⁻¹ range, depending on the type of alkali, the time of immersion in the corresponding base bath and the temperature of immersion. It has been shown that PBI has a remarkable capacity to concentrate KOH, even in an alkaline bath of concentration 3 M. The highest conductivity of KOH-doped PBI (9×10⁻² S cm⁻¹) at 25°C obtained in this work is higher than the we had obtained previously as optimum values for H₂SO₄-doped PBI (5 × 10⁻² S cm⁻¹ at 25°C) and H₃PO₄-doped PBI ( 2 × 10⁻³ S cm⁻¹ at 25°C). PEMFCs based on an alkali-doped PBI membrane were demonstrated, and their characteristics exhibited the same performance as those of PEMFCs based on Nafion® 117. Their development is currently under active investigation.     

A new method for depth-profiling of shallow layers in silicon wafers by repeated chemical etching and total-reflection X-ray fluorescence analysis

A novel method of depth-profiling was applied to a Co-implanted silicon wafer with a dose of nearly 1×10¹⁶ Co atoms cm⁻². A rectangular section (3.4 cm²) was etched repeatedly by oxidation with hydrogen peroxide (30%) and sequential dissolution of each oxidized ‘sublayer’ with a solution of hydrofluoric acid (4%). The mass of the etched oxidized sublayers was determined by differential weighing and the loaded solutions as well as the freshly etched surfaces were analyzed by total-reflection X-ray fluorescence (TXRF). The relative concentration of Co and Si atoms was determined as a function of the depth of each sublayer. These quantities were traced back to the SI-units g g⁻¹ and m by a balance, a magnifier and a certified standard solution or suspension. Two depth-profiles were derived and error bars were calculated to evaluate the precision. Both profiles match quite well and their integration gives dose values which differ by only 8%. The depth resolution of the new method is 0.6 nm at best; the detection limit is 0.003% or 1.5×10¹⁸ Co atoms cm⁻³ for a 2-inch silicon wafer.     

A Sustainable Redox-Flow Battery with an Aluminum-Based,Deep-Eutectic-Solvent Anolyte

Nonaqueous redox-flow batteries are an emerging energy storage technology for grid storage systems, but the development of anolytes has lagged far behind that of catholytes due to the major limitations of the redox species, which exhibit relatively low solubility and inadequate redox potentials. Herein, an aluminum-based deep-eutectic-solvent is investigated as an anolyte for redox-flow batteries. The aluminum-based deep-eutectic solvent demonstrated a significantly enhanced concentration of circa 3.2 m in the anolyte and a relatively low redox potential of 2.2 V vs. Li⁺/Li. The electrochemical measurements highlight that a reversible volumetric capacity of 145 Ah L⁻¹ and an energy density of 189 Wh L⁻¹ or 165 Wh kg⁻¹ have been achieved when coupled with a I₃⁻/I⁻ catholyte. The prototype cell has also been extended to the use of a Br₂-based catholyte, exhibiting a higher cell voltage with a theoretical energy density of over 200 Wh L⁻¹. The synergy of highly abundant, dendrite-free, multi-electron-reaction aluminum anodes and environmentally benign deep-eutectic-solvent anolytes reveals great potential towards cost-effective, sustainable redox-flow batteries.     

Rapid analysis of interaction between six drugs and β2‐adrenergic receptor by injection amount‐dependent method

Drug–protein interaction analysis has become a considerable topic in life science which includes clarifying protein functions, explaining drug action mechanisms and uncovering novel drug candidates. This work was to determine the association constants (K _A ) of six drugs to β ₂‐adrenergic receptor by injection amount‐dependent method using stationary phase containing the immobilized receptor. The values of K _A were calculated to be (25.85 ± 0.035) × 10⁴ m ⁻¹ for clorprenaline, (42.51 ± 0.054) × 10⁴ m ⁻¹ for clenbuterol, (6.67 ± 0.008) × 10⁴ m ⁻¹ for terbutaline, (33.99 ± 0.025) × 10⁴ m ⁻¹ for tulobuterol, (7.59 ± 0.011) × 10⁴ m ⁻¹ for salbutamol and (78.52 ± 0.087) × 10⁴ m ⁻¹ for bambuterol. This rank order agreed well with the data determined by zonal elution, frontal analysis and nonlinear chromatography, even using different batches of β ₂‐AR column. A good correlation was found between the association constants by the current method and radio‐ligand binding assay. Our data indicates that the injection amount‐dependent method is a powerful alternative for rapid analysis of ligand–receptor interactions.     

Controlled Synthesis of 3D Flower‐like Ni2P Composed of Mesoporous Nanoplates for Overall Water Splitting

Developing efficient non‐noble metal and earth‐abundant electrocatalysts with tunable microstructures for overall water splitting is critical to promote clean energy technologies for a hydrogen economy. Herein, novel three‐dimensional (3D) flower‐like Ni₂P composed of mesoporous nanoplates with controllable morphology and high surface area was prepared by a hydrothermal method and low‐temperature phosphidation as efficient electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Compared with the urchin‐like Ni_x P_y , the 3D flower‐like Ni₂P with a diameter of 5 μm presented an efficient and stable catalytic performance in 0.5 m H₂SO₄, with a small Tafel slope of 79 mV dec⁻¹ and an overpotential of about 240 mV at a current density of 10 mA cm⁻² with a mass loading density of 0.283 mg cm⁻². In addition, the catalyst also exhibited a remarkable performance for the OER in 1.0 m KOH electrolyte, with an overpotential of 320 mV to reach a current density of 10 mA cm⁻² and a small Tafel slope of 72 mV dec⁻¹. The excellent catalytic performance of the as‐prepared Ni₂P may be ascribed to its novel 3D morphology with unique mesoporous structure.