A strain sensing structure with high gauge factors (GFs) is designed by engineering channel cracks in a gold thin film. The developed strain sensors possess GFs as high as 200 (ε < 0.5%), 1000 (0.5% < ε < 0.7%), and even exceeding 5000 (0.7% < ε < 1%).
Automated individual tree crown detection and delineation (ITCD) using remotely sensed data plays an increasingly significant role in efficiently, accurately, and completely monitoring forests. This paper reviews trends in ITCD research from 1990-2015 from several perspectives-data/forest type, method applied, accuracy assessment and research objective-with a focus on studies using LiDAR data. This review shows that active sources are becoming more prominent in ITCD studies. Studies using active data-LiDAR in particular-accounted for 80% of the total increase over the entire time period, those using passive data or fusion of passive and active data comprised relatively small proportions of the total increase (8% and 12%, respectively). Additionally, ITCD research has moved from incremental adaptations of algorithms developed for passive data sources to innovative approaches that take advantage of the novel characteristics of active datasets like LiDAR. These improvements make it possible to explore more complex forest conditions (e.g., closed hardwood forests, suburban/urban forests) rather than a single forest type although most published ITCD studies still focused on closed softwood (41%) or mixed forest (22%). Approximately one-third of studies applied individual tree level (30%) assessment, with only a quarter reporting more comprehensive multi-level assessment (23%). Almost one-third of studies (32%) that concentrated on forest parameter estimation based on ITCD results had no ITCD-specific evaluation. Comparison of methods continues to be complicated by both choice of reference data and assessment metric; it is imperative to establish a standardized two-level assessment framework to evaluate and compare ITCD algorithms in order to provide specific recommendations about suitable applications of particular algorithms. However, the evolution of active remotely sensed data and novel platforms implies that automated ITCD will continue to be a promising technology and an attractive research topic for both the forestry and remote sensing communities.
Graphene has demonstrated great potential in next-generation electronics due to its unique two-dimensional structure and properties including a zero-gap band structure, high electron mobility, and high electrical and thermal conductivity. The integration of atom-thick graphene into a device always involves its interaction with a supporting substrate by van der Waals forces and other intermolecular forces or even covalent bonding, and this is critical to its real applications. Graphene films on different surfaces are expected to exhibit significant differences in their properties, which lead to changes in their morphology, electronic structure, surface chemistry/physics, and surface/interface states. Therefore, a thorough understanding of the surface/interface properties is of great importance. In this review, we describe the major "graphene-on-surface" structures and examine the roles of their properties and related phenomena in governing the overall performance for specific applications including optoelectronics, surface catalysis, anti-friction and superlubricity, and coatings and composites. Finally, perspectives on the opportunities and challenges of graphene-on-surface systems are discussed.
A highly efficient low-band-gap (1.2-0.8 eV) photoelectrode is critical for accomplishing efficient conversion of visible-near-infrared sunlight into storable hydrogen. Herein, we report an SbSe polycrystalline thin-film photocathode having a low band gap (1.2-1.1 eV) for efficient hydrogen evolution for wide solar-spectrum utilization. The photocathode was fabricated by a facile thermal evaporation of a single SbSe powder source onto the Mo-coated soda-lime glass substrate, followed by annealing under Se vapor and surface modification with an antiphotocorrosive CdS/TiO bilayer and Pt catalyst. The fabricated SbSe(Se-annealed)/CdS/TiO/Pt photocathode achieves a photocurrent density of ca. -8.6 mA cm at 0 V, an onset potential of ca. 0.43 V, a stable photocurrent for over 10 h, and a significant photoresponse up to the near-infrared region (ca. 1040 nm) in near-neutral pH buffered solution (pH 6.5) under AM 1.5G simulated sunlight. The obtained photoelectrochemical performance is attributed to the reliable synthesis of a micrometer-sized SbSe (Se-annealed) thin film as photoabsorber and the successful construction of an appropriate p-n heterojunction at the electrode-liquid interface for effective charge separation. The demonstration of a low-band-gap and high-performance SbSe photocathode with facile fabrication might facilitate the development of cost-effective PEC devices for wide solar-spectrum utilization.
Small-molecule-linked DNA has emerged as a versatile tool for the interaction assay between small organic molecules and their protein receptors. We report herein the proof-of-principle of a terminal protection assay of small-molecule-linked DNA. This assay is based on our new finding that single-stranded DNA (ssDNA) terminally tethered to a small molecule is protected from the degradation by exonuclease I (Exo I) when the small molecule moiety is bound to its protein target. This finding translates the binding of small molecules to proteins into the presence of a specific DNA sequence, which enables us to probe the interaction between small organic molecules and their protein targets using various DNA sequence amplification and detection technologies. On the basis of selective assembly of single-walled carbon nanotubes (SWNTs) with surface-tethered small-molecule-linked ssDNA not protected by protein binding, a novel electrochemical strategy for terminal protection assay has been developed. Through detecting the redox signal mediated by SWNT assembly on a 16-mercaptohexadecanoic acid-blocked electrode, this strategy is able to ensure substantial signal amplification and a low background current. This strategy is demonstrated for quantitative analysis of the interaction of folate with a tumor biomarker of folate receptor (FR), and a detection limit of 3 pM FR is readily achieved with desirable specificity and sensitivity, indicating that the terminal protection assay can offer a promising platform for small molecule-protein interaction studies.
New Y type chromophores were synthesized and the hyperpolarizability can be effectively translated into large electro-optic coefficients in poled polymers.
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