bluuebunny/crossref_metadata_2025_split huggingface dataset:
Depth‐Resolved Physicochemical Characteristics of Active Layer and Permafrost Soils in an Arctic Polygonal Tundra Region
Authors: Wu Yuxin , Ulrich Craig , Kneafsey Timothy , Lopez Robin , Chou Chunwei , Geller Jil , McKnight Katie , Dafflon Baptiste , Soom Florian , Peterson John , Hubbard Susan 
Published: March 2018

AbstractPermafrost physicochemical parameters play a key role in controlling the response of permafrost carbon to climate change. We studied the physicochemical parameters of permafrost in an Arctic tundra region to evaluate (1) how soil parameters vary with depth and whether and how they are interrelated, (2) whether and how permafrost soil differs from its overlaying active layer, and (3) whether soil property‐depth relationships are different across geomorphic features (e.g., low, flat, and high centered polygons). We also explored the possible biogeochemical processes that led to these soil characteristics and how they may affect biogeochemical reactions upon permafrost thaw. We observed (1) consistent relationships between soil property and depth and between major parameters, (2) large contrasts of key soil parameters between active layer and permafrost, indicative of potentially different response of the permafrost carbon to warming when compared to the active layer, and (3) a correlation between soil hydraulic conductivity and topographic features that impacts soil hydrologic processes. Our analysis suggests that the permafrost has a marine‐derived chemical signature that differs from the active layer and shapes the physicochemical fingerprints of the different geomorphic features. Specifically, we revealed the unique signatures of the high center polygons, indicative of possible microbial activity at depth (>1 m). Our study suggested consistent key soil parameter‐depth correlations while demonstrating complex lateral and vertical variabilities. These results are valuable for identifying approaches to upscale point‐based measurements and for improving model parameterization to predict permafrost carbon behavior and feedback under future climate.
Improved Conventional PCR Assay for Detecting Tetracapsuloides bryosalmonae DNA in Fish Tissues
Authors: Hutchins Patrick R. , Sepulveda Adam J. , Martin Renee M. , Hopper Lacey R. 
Published: March 2018

Abstract
Conventional PCR is an established method to detect Tetracapsuloides bryosalmonaeDNA in fish tissues and to confirm diagnosis of proliferative kidney disease (PKD) caused by T. bryosalmonae. However, the commonly used PKX5f-6r primers were designed with the intention of obtaining sequence information and are suboptimal for determining parasite DNA presence. A new PCR assay to detect T. bryosalmonae 18s rDNA, PKX18s1266f-1426r, is presented that demonstrates specificity, repeatability, and enhanced sensitivity over the PKX5f-6r assay. The limit of detection of the PKX18s1266f-1426r assay at 95% confidence was 100 template copies, and the new primers detected parasite DNA more consistently at template concentrations below 100 copies than did PKX5f-6r. The PKX18s1266f-1426r also achieved 100% detection at sample DNA concentrations one order of magnitude lower than PKX5f-6r. Out of 127 salmonid fish with unknown T. bryosalmonae infection status, PKX5f-6r detected 35 positive samples, while the new assay detected 43. The discrepancy in T. bryosalmonae detection between the two primer sets may be attributed to several differences between the assays, including oligonucleotide melting temperatures, the use of a touchdown PCR thermal cycle, and amplicon length.
Comparison of measured electron energy spectra for six matched, radiotherapy accelerators
Authors: McLaughlin David J. , Hogstrom Kenneth R. , Neck Daniel W. , Gibbons John P. 
Published: March 2018

AbstractThis study compares energy spectra of the multiple electron beams of individual radiotherapy machines, as well as the sets of spectra across multiple matched machines. Also, energy spectrum metrics are compared with central‐axis percent depth‐dose (PDD) metrics.MethodsA lightweight, permanent magnet spectrometer was used to measure energy spectra for seven electron beams (7–20 MeV) on six matched Elekta Infinity accelerators with the MLCi2 treatment head. PDD measurements in the distal falloff region provided R50 and R80–20 metrics in Plastic Water®, which correlated with energy spectrum metrics, peak mean energy (PME) and full‐width at half maximum (FWHM).ResultsVisual inspection of energy spectra and their metrics showed whether beams on single machines were properly tuned, i.e., FWHM is expected to increase and peak height decrease monotonically with increased PME. Also, PME spacings are expected to be approximately equal for 7–13 MeV beams (0.5‐cm R90 spacing) and for 13–16 MeV beams (1.0‐cm R90 spacing). Most machines failed these expectations, presumably due to tolerances for initial beam matching (0.05 cm in R90; 0.10 cm in R80–20) and ongoing quality assurance (0.2 cm in R50). Also, comparison of energy spectra or metrics for a single beam energy (six machines) showed outlying spectra. These variations in energy spectra provided ample data spread for correlating PME and FWHM with PDD metrics. Least‐squares fits showed that R50 and R80–20 varied linearly and supralinearly with PME, respectively; however, both suggested a secondary dependence on FWHM. Hence, PME and FWHM could serve as surrogates for R50 and R80–20 for beam tuning by the accelerator engineer, possibly being more sensitive (e.g., 0.1 cm in R80–20 corresponded to 2.0 MeV in FWHM).ConclusionsResults of this study suggest a lightweight, permanent magnet spectrometer could be a useful beam‐tuning instrument for the accelerator engineer to (a) match electron beams prior to beam commissioning, (b) tune electron beams for the duration of their clinical use, and (c) provide estimates of PDD metrics following machine maintenance. However, a real‐time version of the spectrometer is needed to be practical.
Modeling of the metallic port in breast tissue expanders for photon radiotherapy
Authors: Yoon Jihyung , Xie Yibo , Heins David , Zhang Rui 
Published: March 2018

AbstractThe purpose of this study was to model the metallic port in breast tissue expanders and to improve the accuracy of dose calculations in a commercial photon treatment planning system (TPS). The density of the model was determined by comparing TPS calculations and ion chamber (IC) measurements. The model was further validated and compared with two widely used clinical models by using a simplified anthropomorphic phantom and thermoluminescent dosimeters (TLD) measurements. Dose perturbations and target coverage for a single postmastectomy radiotherapy (PMRT) patient were also evaluated. The dimensions of the metallic port model were determined to be 1.75 cm in diameter and 5 mm in thickness. The density of the port was adjusted to be 7.5 g/cm3 which minimized the differences between IC measurements and TPS calculations. Using the simplified anthropomorphic phantom, we found the TPS calculated point doses based on the new model were in agreement with TLD measurements within 5.0% and were more accurate than doses calculated based on the clinical models. Based on the photon treatment plans for a real patient, we found that the metallic port has a negligible dosimetric impact on chest wall, while the port introduced significant dose shadow in skin area. The current clinical port models either overestimate or underestimate the attenuation from the metallic port, and the dose perturbation depends on the plan and the model in a complex way. TPS calculations based on our model of the metallic port showed good agreement with measurements for all cases. This new model could improve the accuracy of dose calculations for PMRT patients who have temporary tissue expanders implanted during radiotherapy and could potentially reduce the risk of complications after the treatment.
Mechanical Considerations for Electrospun Nanofibers in Tendon and Ligament Repair
Authors: Brennan David A. , Conte Adriano A. , Kanski Gregory , Turkula Stefan , Hu Xiao , Kleiner Matthew T. , Beachley Vince 
Published: March 2018

AbstractElectrospun nanofibers possess unique qualities such as nanodiameter, high surface area to volume ratio, biomimetic architecture, and tunable chemical and electrical properties. Numerous studies have demonstrated the potential of nanofibrous architecture to direct cell morphology, migration, and more complex biological processes such as differentiation and extracellular matrix (ECM) deposition through topographical guidance cues. These advantages have created great interest in electrospun fibers for biomedical applications, including tendon and ligament repair. Electrospun nanofibers, despite their nanoscale size, generally exhibit poor mechanical properties compared to larger conventionally manufactured polymer fiber materials. This invites the question of what role electrospun polymer nanofibers can play in tendon and ligament repair applications that have both biological and mechanical requirements. At first glance, the strength and stiffness of electrospun nanofiber grafts appear to be too low to fill the rigorous loading conditions of these tissues. However, there are a number of strategies to enhance and tune the mechanical properties of electrospun nanofiber grafts. As researchers design the next‐generation electrospun tendon and ligament grafts, it is critical to consider numerous physiologically relevant mechanical criteria and to evaluate graft mechanical performance in conditions and loading environments that reflect in vivo conditions and surgical fixation methods.
Long Electron–Hole Diffusion Length in High‐Quality Lead‐Free Double Perovskite Films
Authors: Ning Weihua , Wang Feng , Wu Bo , Lu Jun , Yan Zhibo , Liu Xianjie , Tao Youtian , Liu Jun‐Ming , Huang Wei , Fahlman Mats , Hultman Lars , Sum Tze Chien , Gao Feng 
Published: March 2018

AbstractDeveloping environmentally friendly perovskites has become important in solving the toxicity issue of lead‐based perovskite solar cells. Here, the first double perovskite (Cs2AgBiBr6) solar cells using the planar structure are demonstrated. The prepared Cs2AgBiBr6 films are composed of high‐crystal‐quality grains with diameters equal to the film thickness, thus minimizing the grain boundary length and the carrier recombination. These high‐quality double perovskite films show long electron–hole diffusion lengths greater than 100 nm, enabling the fabrication of planar structure double perovskite solar cells. The resulting solar cells based on planar TiO2 exhibit an average power conversion efficiency over 1%. This work represents an important step forward toward the realization of environmentally friendly solar cells and also has important implications for the applications of double perovskites in other optoelectronic devices.
Strongly Coupled Tin‐Halide Perovskites to Modulate Light Emission: Tunable 550–640 nm Light Emission (FWHM 36–80 nm) with a Quantum Yield of up to 6.4%
Authors: Chen Min‐Yi , Lin Jin‐Tai , Hsu Chia‐Shuo , Chang Chung‐Kai , Chiu Ching‐Wen , Chen Hao Ming , Chou Pi‐Tai 
Published: March 2018

AbstractColloidal perovskite quantum dots represent one of the most promising materials for applications in solar cells and photoluminescences. These devices require a low density of crystal defects and a high yield of photogenerated carriers, which are difficult to realize in tin‐halide perovskite because of the intrinsic instability of tin during nucleation. Here, an enhancement in the luminescent property of tin‐halide perovskite nanoplates (TPNPs) that are composed of strongly coupled layered structures with the chemical formula of PEA2SnX4 (PEA = C6H5(CH2)2NH3, X = Br, I) is reported. TPNPs (X = I) show an emission at a wavelength of 640 nm, with high quantum yield of 6.40 ± 0.14% and full width at half maximum (FWHM) as small as 36 nm. The presence of aliphatic carboxylic acid is found to play a key role in reducing the tin perovskite defect density, which significantly improves the emission intensity and stability of TPNPs. Upon mixing iodo‐ and bromo‐ precursors, the emission wavelength is successfully tuned from 640 nm (PEA2SnI4) to 550 nm (PEA2SnBr4), with a corresponding emission quantum yield and FWHM of 0.16–6.40% and 36–80 nm, respectively. The results demonstrate a major advance for the emission yield and tunability of tin‐halide perovskites.
Wood‐Inspired High‐Performance Ultrathick Bulk Battery Electrodes
Authors: Lu Lei‐Lei , Lu Yu‐Yang , Xiao Zi‐Jian , Zhang Tian‐Wen , Zhou Fei , Ma Tao , Ni Yong , Yao Hong‐Bin , Yu Shu‐Hong , Cui Yi 
Published: March 2018

AbstractUltrathick electrode design is a promising strategy to enhance the specific energy of Li‐ion batteries (LIBs) without changing the underlying materials chemistry. However, the low Li‐ion conductivity caused by ultralong Li‐ion transport pathway in traditional random microstructured electrode heavily deteriorates the rate performance of ultrathick electrodes. Herein, inspired by the vertical microchannels in natural wood as the highway for water transport, the microstructures of wood are successfully duplicated into ultrathick bulk LiCoO2 (LCO) cathode via a sol–gel process to achieve the high areal capacity and excellent rate capability. The X‐ray‐based microtomography demonstrates that the uniform microchannels are built up throughout the whole wood‐templated LCO cathode bringing in 1.5 times lower of tortuosity and ≈2 times higher of Li‐ion conductivity compared to that of random structured LCO cathode. The fabricated wood‐inspired LCO cathode delivers high areal capacity up to 22.7 mAh cm−2 (five times of the existing electrode) and achieves the dynamic stress test at such high areal capacity for the first time. The reported wood‐inspired design will open a new avenue to adopt natural hierarchical structures to improve the performance of LIBs.
Responsive Block Copolymer Photonic Microspheres
Authors: Yang Yi , Kim Hodae , Xu Jiangping , Hwang Min‐Soo , Tian Di , Wang Ke , Zhang Lianbin , Liao Yonggui , Park Hong‐Gyu , Yi Gi‐Ra , Xie Xiaolin , Zhu Jintao 
Published: April 2018

AbstractResponsive photonic crystals (PCs) have attracted much attention due to their broad applications in the field of chemical and physical sensing through varying optical properties when exposed to external stimuli. In particular, assembly of block copolymers (BCPs) has proven to be a robust platform for constructing PCs in the form of films or bulk. Here, the generation of BCPs photonic microspheres is presented with 3D periodical concentric lamellar structures through confined self‐assembly. The structural color of the spherical PCs can be tuned by selective swelling of one block, yielding large change of optical property through varying both layer thickness and refraction index of the domains. The as‐formed spherical PCs demonstrate large reflection wavelength shift (≈400–700 nm) under organic solvent permeation and pH adjustment. Spherical shape and structural symmetry endow the formed spherical PCs with rotation independence and monochrome, which is potentially useful in the fields of displays, sensing, and diagnostics.
Polarization Encoded Color Image Embedded in a Dielectric Metasurface
Authors: Zang Xiaofei , Dong Fengliang , Yue Fuyong , Zhang Chunmei , Xu Lihua , Song Zhiwei , Chen Ming , Chen Pai‐Yen , Buller Gerald S. , Zhu Yiming , Zhuang Songlin , Chu Weiguo , Zhang Shuang , Chen Xianzhong 
Published: March 2018

AbstractOptical metasurfaces have shown unprecedented capabilities in the local manipulation of the light's phase, intensity, and polarization profiles, and represent a new viable technology for applications such as high‐density optical storage, holography and display. Here, a novel metasurface platform is demonstrated for simultaneously encoding color and intensity information into the wavelength‐dependent polarization profile of a light beam. Unlike typical metasurface devices in which images are encoded by phase or amplitude modulation, the color image here is multiplexed into several sets of polarization profiles, each corresponding to a distinct color, which further allows polarization modulation‐induced additive color mixing. This unique approach features the combination of wavelength selectivity and arbitrary polarization control down to a single subwavelength pixel level. The encoding approach for polarization and color may open a new avenue for novel, effective color display elements with fine control over both brightness and contrast, and may have significant impact for high‐density data storage, information security, and anticounterfeiting.
Synthetic Biology Makes Polymer Materials Count
Authors: Beyer Hannes M. , Engesser Raphael , Hörner Maximilian , Koschmieder Julian , Beyer Peter , Timmer Jens , Zurbriggen Matias D. , Weber Wilfried 
Published: March 2018

AbstractSynthetic biology applies engineering concepts to build cellular systems that perceive and process information. This is achieved by assembling genetic modules according to engineering design principles. Recent advance in the field has contributed optogenetic switches for controlling diverse biological functions in response to light. Here, the concept is introduced to apply synthetic biology switches and design principles for the synthesis of multi‐input‐processing materials. This is exemplified by the synthesis of a materials system that counts light pulses. Guided by a quantitative mathematical model, functional synthetic biology‐derived modules are combined into a polymer framework resulting in a biohybrid materials system that releases distinct output molecules specific to the number of input light pulses detected. Further demonstration of modular extension yields a light pulse‐counting materials system to sequentially release different enzymes catalyzing a multistep biochemical reaction. The resulting smart materials systems can provide novel solutions as integrated sensors and actuators with broad perspectives in fundamental and applied research.
Direct Synthesizing In‐Plane Heterostructures of Graphene and Hexagonal Boron Nitride in Designed Pattern
Authors: Zhang Shiyu , Li Jidong , Wu Hongrong , Li Xuemei , Guo Wanlin 
Published: April 2018

AbstractIn‐plane heterostructure of graphene (G) and hexagonal boron nitride (h‐BN) has attracted increasing attentions owing to its exceptional properties and potentials in atomically thin circuitry. However, direct growth of patterned in‐plane G/h‐BN heterostructures (G‐BNs) by chemical vapor deposition (CVD) method in a controllable way remains a great challenge. Here, a reliable way to directly synthesize G‐BN in designed pattern by one CVD step is demonstrated. First, ultraviolet lithography and magnetron sputtering are utilized to deposit nickel nanofilm in designed pattern onto copper foil surface. Then the copper foil with prepatterned nickel nanofilm is used as the synthesis substrate. Benefiting from different mechanisms of graphene growth on Cu and Cu–Ni alloy surfaces, graphene grows solely on the Ni‐free surface of the substrate, followed by h‐BN growth on the exposed Ni‐pattern surface, realizing the direct growth of patterned G‐BN. The method presented here paves a viable road for controllable growth of 2D in‐plane heterostructures for variable applications.
Recent Advances in Halide Perovskite Photodetectors Based on Different Dimensional Materials
Authors: Wangyang Peihua , Gong Chuanhui , Rao Gaofeng , Hu Kai , Wang Xuepeng , Yan Chaoyi , Dai Liping , Wu Chunyang , Xiong Jie 
Published: March 2018

AbstractBased on the understanding and control of the energy levels and density of defect states of 0D, 1D, 2D, and 3D materials, halide perovskite photodetectors (HPPDs) based on different dimensional materials have recently gained significant achievements. In addition, the detection range of HPPDs even extended from ultraviolet–visible–near infrared (UV–vis–NIR) to X/γ photons, and the self‐powered HPPDs also became a hot issue. In this review, a comprehensive summary of the recent advances in HPPDs based on different dimensional materials is proposed, including 0D, 1D, 2D, and 3D perovskite and nonperovskite (without perovskite ABX3 crystal structure) materials, focusing on the relationship among the charge‐carrier transport, operation mechanism, device architectures, and photodetecting performances. First, an introduction of composition and crystal structures of HPPDs is given, followed by the description of their key figure‐of‐merit parameters evaluation system. Next, the recent developments of HPPDs based on different dimensional materials are highlighted. And finally, the characteristics of HPPDs depending on the dimensionality are summarized, and the potential challenges and approaches for future study are also presented.
One‐Pot Synthesis of Fused N,O‐Heterocycles through Rh(III)‐Catalyzed Cascade Reactions of Aromatic/Vinylic N‐Alkoxy‐ Amides with 4‐Hydroxy‐2‐Alkynoates
Authors: Xu Yuanshuang , Li Bin , Zhang Xinying , Fan Xuesen 
Published: March 2018

AbstractA highly efficient and regioselective synthesis of furo[3,4‐c]isoquinoline‐1,5(3H,4H)‐diones and furo[3,4‐b]pyridine‐2,5(1H,7H)‐diones via Rh(III)‐catalyzed one‐pot cascade reactions of aromatic/vinylic N‐alkoxyamides with 4‐hydroxy‐2‐alkynoates is presented. Mechanistically, the formation of the title compounds is triggered by a Rh(III)‐catalyzed inert C(sp2)−H bond activation of the amide substrate followed by its [4+2] annulation and lactonization with 4‐hydroxy‐2‐alkynoate featuring with an oxidizing and partially traceless directing group. To the best of our knowledge, this is the first example in which both the furan‐2(5H)‐one and the pyridin‐2(1H)‐one scaffolds are constructed in one pot under one set of reaction conditions. Compared with literature methods, notable features of this new protocol include facile formation of bis‐heterocyclic scaffolds from readily available acyclic substrates, broad substrate scope with good tolerance of a wide range of functional groups, excellent regioselectivity and high efficiency.magnified image
Construction of All‐Carbon Quaternary Stereocenters via Asymmetric Cyclopropanations: Synthesis of Chiral Carbocyclic Pyrimidine Nucleosides
Authors: Wang Hai‐Xia , Guan Fang‐Juan , Xie Ming‐Sheng , Qu Gui‐Rong , Guo Hai‐Ming 
Published: March 2018

AbstractAn efficient route to synthesize chiral carbocyclic pyrimidine nucleoside analogues containing all‐carbon quaternary stereocenters has been established via the asymmetric intermolecular cyclopropanation of N1‐vinylpyrimidines and α‐aryl diazoesters. With 2 mol% of chiral dirhodium (II) carboxylate complex as the catalyst, a variety of chiral carbocyclic cytosine or uracil nucleoside analogues were obtained in good yields (up to 96% yield), high diastereoselectivities (>20:1 dr), and excellent enantioselectivities (up to 99% ee).magnified image
Palladium‐Catalyzed Domino Dehydrogenation/Heck‐Type Reactions of Carbonyl Compounds
Authors: Le Bras Jean , Muzart Jacques 
Published: March 2018

AbstractThis review covers those domino reactions that involve, at least, both palladium‐catalyzed dehydrogenation of carbonyl compounds and Heck‐type reactions. While the former occurs under Pd(II) catalysis, a Pd(0) or Pd(II) catalyst is required for the latter, depending on the nature of the (hetero)arylating agent, ArX or ArH, respectively. Regeneration of the Pd(II) species is assumed to proceed by either an oxidant or the aryl halide. Proposed mechanisms are described with, in some cases, personal comments.magnified image