Wear-resisting Oxide Films for 900℃

A study was conducted to develop low-friction, wear-resistant surfaces on high temperature alloys for the temperature range from 26℃ to 900℃. The approach investigated consists of modifying the naturally occurring oxide film in order to improve its tribological properties. Improvement is needed at low temperatures where the oxide film, previously formed at high temperature, spalls due to stresses induced by sliding. Experiments with Ti, W and Ta additions show a beneficial effect when added to Ni and Ni-base alloys. Low friction can be maintained down to 100℃ from 900℃. For unalloyed Ni friction and surface damage increases at 400℃ to 500℃. Two new alloys were perpared based on the beneficial results of binary alloys and ZrO2 diffusion in Ni.Low friction at temperature above 500℃ and reasonable values (0.32~0.42) at low temperature are obtained.     

Nickel Oxide as an Electrode Material for Supercapacitors

The preparation of Ni oxide films and their capacitive mechanism are discussed in this paper.Nickel oxide film electrodes perform pseudocapacitance in aqueous KOH and NaOH but perform double layer capacitance in LiClO4/PC(propylence carbonate).The effect of increasing the specific capacitance was observed when Ni oxide film electrodes are doped with Co.A specific capacitance of around 70 F/g was achieved when using Ni oxide films doped with Co as electrodes and 1mol/L aqueous KOH or NaOH as an electrolyte.     

Near-Infrared Light-Responsive Nitric Oxide Delivery Platform for Enhanced Radioimmunotherapy

Radiotherapy(RT)is a widely used way for cancer treatment.However,the efficiency of RT may come with various challenges such as low specificity,limitation by resistance,high dose and so on.Nitric oxide(NO)is known a very effective radiosensitizer of hypoxic tumor.However,NO cannot circulate in body with high concentration.Herein,an NIR light-responsive NO delivery system is developed for controlled and precisely release of NO to hypoxic tumors during radiotherapy.Tert-Butyl nitrite,which is an efficient NO source,is coupled to Ag2S quantum dots(QDs).NO could be generated and released from the Ag2S QDs effectively under the NIR irradiation due to the thermal effect.In addition,Ag is also a type of heavy metal that can benefit the RT therapy.We demonstrate that Ag2S NO delivery platforms remarkably maximize radiotherapy effects to inhibit tumor growth in CT26 tumor model.Furthermore,immunosuppressive tumor microenvironment is improved by our NO delivery system,significantly enhancing the anti-PD-L1 immune checkpoint blockade therapy.100% survival rate is achieved by the radio-immune combined therapy strategy based on the Ag2S NO delivery platforms.Our results suggest the promise of Ag2S NO delivery platforms for multifunctional cancer radioimmunotherapy.     

D-Band Center Optimization of Edge-Rich Ultrathin RuZn Nanosheets With Moiré Superlattices for pH-Universal Hydrogen Evolution Reaction

Electrocatalytic hydrogen evolution reaction (HER) is a promising way to produce pure and clean hydrogen. However, the preparation of efficient and economical catalysts for pH-universal HER remains a challenging but rewarding task. Herein, ultrathin RuZn nanosheets (NSs) with moiré superlattices and abundant edges are synthesized. The RuZn NSs with unique structure exhibit superb HER performance with overpotentials of 11, 13, and 29 mV to achieve 10 mA cm⁻² in 1 M KOH, 1 M PBS, and 0.5 M H₂SO₄, respectively, which is substantially lower than those of Ru NSs and RuZn NSs without moiré superlattices. Density functional theory investigations reveal that the charge transfer from Zn to Ru will lead the appropriate downshift of the d-band center of surface Ru atoms, thus accelerating hydrogen desorption from the Ru sites, lowering the dissociation energy barrier of water and greatly improving the HER performance. This work provides an effective design scheme for high-performance HER electrocatalysts over a wide pH range, and propose a general route to prepare Ru-based bimetallic nanosheets with moiré superlattices.     

Cell-Derived Vesicles for Antibiotic Delivery—Understanding the Challenges of a Biogenic Carrier System

Recently, extracellular vesicles (EVs) sparked substantial therapeutic interest, particularly due to their ability to mediate targeted transport between tissues and cells. Yet, EVs’ technological translation as therapeutics strongly depends on better biocompatibility assessments in more complex models and elementary in vitro–in vivo correlation, and comparison of mammalian versus bacterial vesicles. With this in mind, two new types of EVs derived from human B-lymphoid cells with low immunogenicity and from non-pathogenic myxobacteria SBSr073 are introduced here. A large-scale isolation protocol to reduce plastic waste and cultivation space toward sustainable EV research is established. The biocompatibility of mammalian and bacterial EVs is comprehensively evaluated using cytokine release and endotoxin assays in vitro, and an in vivo zebrafish larvae model is applied. A complex three-dimensional human cell culture model is used to understand the spatial distribution of vesicles in epithelial and immune cells and again used zebrafish larvae to study the biodistribution in vivo. Finally, vesicles are successfully loaded with the fluoroquinolone ciprofloxacin (CPX) and showed lower toxicity in zebrafish larvae than free CPX. The loaded vesicles are then tested effectively on enteropathogenic Shigella, whose infections are currently showing increasing resistance against available antibiotics.     

Electron Effective Mass and Momentum Relaxation Time in One-Sided δ-Doped PHEMT AlGaAs/InGaAs/GaAs Quantum Wells with High Electron Density

Technical Physics Letters - Using the Shubnikov–de Haas effect, the dependences of electron effective mass m* and transport and quantum momentum relaxation times in...     

Zinc Oxide Nanostructures for NO2 Gas–Sensor Applications: A Review

Nano-Micro Letters - Because of the interesting and multifunctional properties, recently, ZnO nanostructures are considered as excellent material for fabrication of highly sensitive and selective...     

Oxide single crystals for research and production—an adventure for producer and user or functional technique?

Oxide single crystals have been used during the last 100 years in very different industries. In the first 50 years the jewellery and watch industries were the main users of oxide single crystals like ruby, sapphire and spinel. At that time Europe was the main producer of oxide crystals. Production plants were in France, Switzerland and Germany. In the Second World War the aviation industry started to use these materials for instrumentation systems. This production was mainly in the USA, Russia and Germany. Today, the use of all kinds of oxide single crystals is well established within many industries. However, only a small range of crystals is used in very high quantities. These are crystals such as quartz, aluminium oxide, titanium dioxide, strontium titanate, lithium niobate and tantalate, BBO and garnets. The other crystal materials are widely developed at R&D centres and universities but not really in industrial production. Among the problems are the unstable market places and the rapid change in material specifications from OEM customers.     

A Novel Deflection Method for Measuring the Growth Stress of Thermally Growing Oxide Scales

A kind of new deflection technique has been developed for measuring the growth stress of thermally growing oxide scales during high temperature oxidation of alloys. The average growth stresses in oxide scales such as Al2O3, NiO and Cr2O3 formed on the surface of the superalloys can be investigated by this technique. Unlike the comventional deflection method, the novel method does not need to apply a coating for preventing one main face of thin strip specimen from oxidizing and can be used under the condition of longer time and higher temperature.     

Layered δ-MnO2 as positive electrode for lithium intercalation

Layer structured δ-MnO₂ was synthesized by a microwave-assisted hydrothermal method. The morphology of the product consists of flower-like spheres that range from about 200 nm to 3 μm in diameter and are composed of sheets about 5-10 nm in thickness. When tested in the voltage range of 2 to 4.5 V vs. Li⁺/Li in coin cells, the separator is blocked, handicapping Li⁺ conductivity and leading to cell failure. When tested in the voltage range of 2 to 4 V in ethylene carbonate/dimethyl carbonate (EC/DMC), the δ-MnO₂ delivers an initial reversible capacity of 143.7 mAh g⁻¹ and can maintain 120 mAh g⁻¹ at the 60th cycle. The δ-MnO₂ electrode shows good cycling stability at different current densities and delivers a discharge capacity of about 90 mAh g⁻¹ at 1 C, indicating that it is a promising cathode material for lithium ion batteries.     

Assembled β-Co(OH)2 Nanoparticles on Reduced Graphene Oxide for Enhanced Magnetism

A simple and effective method has been developed to assemble the β-Co(OH)₂ nanoparticles coordinated to the surface of the reduced graphene oxide sheets. The reduced graphene oxide-Co(OH)₂ hybrid is characterized by transmission electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy techniques, respectively. These morphological and structural analysis results demonstrate the successful attachment of hexagonal β-Co(OH)₂ nanoparticles to the reduced graphene oxide sheets through the oxygen-containing functional groups. Compared to the paramagnetic property of hexagonal β-Co(OH)₂ nanoparticles, a s-like superparamagnetic behavior can be observed at room temperature for the reduced graphene oxide-Co(OH)₂ hybrid by the magnetometer PPMS-9T magnetic measurement, indicative of superparamagnetism. The interplay between the localized magnetic moment of the Co²⁺ ions in the hexagonal β-Co(OH)₂ nanoparticles and the itinerant π carriers in reduced graphene oxide is suggested to be responsible for this superparamagnetic behavior. This enhanced magnetism indicates that the reduced graphene oxide-Co(OH)₂ hybrid has a promising potential for spintronic device applications.     

An Exploration of a New Running Mode of Equipment Management for Institutions of Higher Learning

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An On-Line Technique for the Determination of the δ(18)O and δ(17)O of Gaseous and Dissolved Oxygen

Few studies have used the stable isotopic composition of O(2) as a tracer of gas transport or biogeochemical processes in environmental research. Here we demonstrate field sampling techniques for gaseous and dissolved O(2) and describe an analytical method for measuring δ(18)O and δ(17)O values of O(2) in air, soil gas, and water samples using continuous-flow isotope-ratio mass spectrometry (CF-IRMS). A Micromass CF-IRMS was altered to accommodate a sample gas injection port prior to a CO(2) and H(2)O trap and GC column. The GC column was a 1-m, 5-? molecular sieve column held at 35 °C. The resolved sample O(2) was introduced to the IRMS via an open split. δ(18)O and δ(17)O values were determined by measurement of O(2) isotopes at m/z 34/32 and 33/32 and comparison to a reference pulse of O(2). Repeated injections of atmospheric oxygen yielded a repeatability (±SD) of ±0.17‰ for δ(18)O and ±0.5‰ for δ(17)O. IRMS source linearity was excellent for O(2) over a sample size range of 60-400 μL. The smallest sample for routine δ(18)O and δ(17)O determinations was ～80 μL of O(2), with a sample analysis time of 180 s. Preliminary results from a riverine and soil gas study illustrate natural oxygen isotope fractionation processes.     

Correcting for methane interferences on δ2H and δ18O measurements in pore water using H2Oliquid-H2Ovapor equilibration laser spectroscopy

Cavity ring-down spectroscopy (CRDS) is a new and evolving technology that shows great promise for isotopic δ(18)O and δ(2)H analyses of pore water from equilibrated headspace H(2)O vapor from environmental and geologic cores. We show that naturally occurring levels of CH(4) can seriously interfere with CRDS spectra, leading to erroneous δ(18)O and δ(2)H results for water. We created a new CRDS correction algorithm to account for CH(4) concentrations typically observed in subsurface and anaerobic environments, such as ground waters or lake bottom sediments. We subsequently applied the correction method to a series of geologic cores that contain CH(4). The correction overcomes the spectral interference and provides accurate pore water δ(18)O and δ(2)H values with acceptable precision levels as well as accurate concentrations of CH(4).     

Evidence for the existence of faulting in a splat-cooled δ-Pu (Ti) alloy

Examination of X-ray diffraction profiles of a splat-cooled 15 Ti-85 Pu alloy has revealed that the material contains a large amount of twinning coupled with a reasonably small crystallite size and high strain. The localized strain is estimated to be 0.6%, the crystallite size 250 Å, and the twinning fault probability is large at 0.043.     

Boosting electron population in δ-Bi2O3 through iron doping for improved photocatalytic activity

We successfully stabilize the delta phase of bismuth oxide (δ-Bi₂O₃) down to room temperature through a simple hydrothermal method. The prepared δ-Bi₂O₃, which is composed of ultrathin nanosheets, possesses excellent crystallinity. When δ-Bi₂O₃ is doped with Fe³⁺, the photocatalytic activity for the mineralization of a number of refractory organic compounds is improved. The improved photocatalytic activity is caused by an increased electron population upon the Fe³⁺ doping. Additional thermal treatment through a post-calcination at 500?°C under air atmosphere results in further increases of photocatalytic activity due to the improved crystallinity, extended light absorption, and better incorporation of Fe³⁺ into the host lattice.     

Three‑Dimensional Ordered Mesoporous Carbon Spheres Modified with Ultrafine Zinc Oxide Nanoparticles for Enhanced Microwave Absorption Properties

Currently,electromagnetic radiation and interference have a significant effect on the operation of electronic devices and human health systems.Thus,developing excellent microwave absorbers have a huge significance in the material research field.Herein,a kind of ultrafine zinc oxide(ZnO)nanoparticles(NPs)supported on three-dimensional(3D)ordered mesoporous carbon spheres(ZnO/OMCS)is prepared from silica inverse opal by using phenolic resol precursor as carbon source.The prepared lightweight ZnO/OMCS nanocomposites exhibit 3D ordered carbon sphere array and highly dispersed ultrafine ZnO NPs on the mesoporous cell walls of carbon spheres.ZnO/OMCS-30 shows microwave absorbing ability with a strong absorption(?39.3 dB at 10.4 GHz with a small thickness of 2 mm)and a broad effective absorption bandwidth(9.1 GHz).The outstanding microwave absorbing ability benefits to the well-dispersed ultrafine ZnO NPs and the 3D ordered mesoporous carbon spheres structure.This work opened up a unique way for developing lightweight and high-efficient carbon-based microwave absorbing materials.     

The Tendency toward Higher Integration of I.C.and Problems for Copper Based Lead Frame Materials

The inereasing market needs forthe VLSI(Very Large Scale IntegratedCircuit)can be classified as follows:(1)Higher packaging dellsity(2)More advanced and multifarious     

On δ-record observations: asymptotic rates for the counting process and elements of maximum likelihood estimation

Given a sequence of random variables {X _n ,n≥1} and δ∈ℝ, an observation X _n is a δ-record if X _n >max {X ₁,…,X _n−1}+δ. We obtain, for δ≤0, weak and strong laws of large numbers for the counting process of δ-records among the first n observations from a sequence of independent identically distributed random variables, with common distribution F, possibly discontinuous. We provide examples of our results in the context of common probability distributions. Finally, we show how δ-records can be used for maximum likelihood estimation.     

An Algorithm for Cycle-Slip Detection in a Melbourne–Wübbena Combination Formed of Code and Carrier Phase GNSS Measurements

Measurement Techniques - A new algorithm has been developed for the determination and elimination of jumps in the Melbourne–Wübbena combination, formed from the code and phase...