Cryogenic Exfoliation of 2D Stanene Nanosheets for Cancer Theranostics

Stanene(Sn)-based materials have been extensively applied in industrial production and daily life,but their potential biomedi-cal application remains largely un...     

Analysis of the cost‐effectiveness of information networks with applications

This paper presents a methodology for the analysis of the cost‐effectiveness of information networks over a period of time. The cost‐effectiveness is considered to be associated with use‐dependent and use‐independent costs and benefits. Copyright © 2000 John Wiley & Sons, Ltd.     

Long‐range wireless sensor networks with transmit‐only nodes and software‐defined receivers

Wireless sensor networks for environmental monitoring and agricultural applications often face Long‐range requirements at low bit rates together with a large numbers of nodes. This paper presents the design and test of a novel wireless sensor network that combines a large radio range with very low power consumption and cost. Our asymmetric sensor network uses ultra‐low‐cost 40‐MHz transmitters and a sensitive software‐defined radio receiver with multi‐channel capability. Experimental radio range measurements in two different outdoor environments demonstrate a single‐hop range of up to 1.8 km. A theoretical model for radio propagation at 40 MHz in outdoor environments is proposed and validated with the experimental measurements. The reliability and fidelity of network communication over longer periods is evaluated with a deployment for distributed temperature measurements. Our results demonstrate the feasibility of the transmit‐only low‐frequency system design approach for future environmental sensor networks. Although there have been several papers proposing the theoretical benefits of this approach, to the best of our knowledge, this is the first paper to provide experimental validation of such claims. Copyright © 2011 John Wiley & Sons, Ltd.     

Field Emission and Cathodoluminescence of ZnS Hexagonal Pyramids of Zinc Blende Structured Single Crystals

Single‐crystal hexagonal pyramids of zinc blende ZnS are fabricated by facile thermal evaporation in an ammonia atmosphere at 1150 °C. It is found that ZnS pyramids grow along the [111] crystal axis and possess a sharp tip with a diameter of ～10 nm and a micrometer‐sized base. The structural model and growth mechanism are proposed based on crystallographic characteristics. This unique ZnS pyramid structure exhibits a low turn‐on field (2.81 V µm^?1), a high field‐enhancement factor (over 3000), a large field‐emission current density (20 mA cm^?2), and good stability with very small fluctuation (0.9%). These superior field‐emission properties are clearly attributed to the pyramid morphology, with micrometer‐sized bases and nanotips, and high crystallinity. Moreover, a stable UV emission of 337 nm at room temperature is observed and can be ascribed to the band emission of the zinc blende phase. These results suggest that the ZnS hexagonal pyramids can be expected to find promising applications as field emitters and optoelectronic devices.     

Rational Design of Charge‐Neutral,Near‐Infrared‐Emitting Osmium(II) Complexes and OLED Fabrication

A new series of charge neutral Os(II) isoquinolyl triazolate complexes ( 1 – 4 ) with both trans and cis arrangement of phosphine donors are synthesized, and their structural, electrochemical and photophysical properties are established. In sharp contrast to the cis‐arranged complexes 2 – 4 , the trans derivative 1 , which shows a planar arrangement of chromophoric N‐substituted chelates, offers the most effective extended π‐delocalization and hence the lowest excited state energy gap. These complexes exhibit phosphorescence with peak wavelengths ranging from 692–805 nm in degassed CH₂Cl₂ at room temperature. Near‐infrared (NIR)‐emitting electroluminescent devices employing 6 wt % of 1 (or 4 ) doped in Alq₃ host material are successfully fabricated. The devices incorporating 1 as NIR phosphor exhibit fairly intense emission with a peak wavelength at 814 nm. Forward radiant emittance reaches as high as 65.02 µW cm^?2, and a peak EQE of ～1.5% with devices employing Alq₃, TPBi and/or TAZ as electron‐transporting/exciton‐blocking layers. Upon switching to phosphor 4 , the electroluminescence blue shifts to 718 nm, while the maximum EQE and radiance increase to 2.7% and 93.26 (μW cm^?2) respectively. Their performances are optimized upon using TAZ as the electron transporting and exciton‐blocking material. The OLEDs characterized represent the only NIR‐emitting devices fabricated using charge‐neutral and volatile Os(II) phosphors via thermal vacuum deposition.     

An Alternative Route Towards Metal–Polymer Hybrid Materials Prepared by Vapor‐Phase Processing

Transition metals incorporated into polymers lead to unusual or improved physical properties that significantly differ from those of purely organic polymers. A simple and practicable incorporation of diverse transition metals into any available polymer would make an important contribution to overcome some of the synthetic difficulties of metal‐polymer hybrid materials. Here, it is demonstrated that atomic layer deposition (ALD) can be a promising means to resolve some of those difficulties. It is found that even polytetrafluoroethylene (PTFE) with its great physical and chemical stability can be easily transformed into a transition metal–PTFE hybrid material simply by applying a metal‐oxide ALD process to PTFE. Upon metal incorporation into the PTFE, the molecular structure as well as mechanical properties (tensile behavior) of PTFE were observed to significantly change. For a better understanding of the changes to the material, experimental investigations using Raman spectroscopy, attenuated‐total‐reflection Fourier‐transform infrared spectroscopy, wide‐angle X‐ray diffraction, and energy‐dispersive X‐ray analysis were performed. In addition, with density functional theory calculations, potential bonding states of the incorporated metal into PTFE were modeled and predicted. The ALD‐based vapor‐phase approach for metal incorporation into a polymer could bring about rapid progress in the research area of metal–polymer hybrid materials.     

High pressure phase transitions for CdSe

The structure and pressure-induced phase transitions for CdSe are investigated using first-principles calculations. The pressure-induced phase transition sequence WZ/ZB → Rs → Cmcm → CsCl for CdSe is drawn reasonably for the fist time, the corresponding transition pressures are 3.8, 29 and 107 GPa, respectively and the intermediate states between the Cmcm structure and the CsCl structure should exist.     

Development of an Event Stream Processing System for the Vehicle Telematics Environment

In this letter, we present an event stream processing system that can evaluate a pattern query for a data sequence with predicates. We propose a pattern query language and develop a pattern query processing system. In our system, we propose novel techniques for run‐time aggregation and negation processing and apply our system to stream data generated from vehicles to monitor unusual driving patterns.