bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydrodynamic object identification with artificial neural models
Authors: Lakkam Sreetej , Balamurali B. T. , Bouffanais Roland
Published: August 2019

The lateral-line system that has evolved in many aquatic animals enables them to navigate murky fluid environments, locate and discriminate obstacles. Here, we present a data-driven model that uses artificial neural networks to process flow data originating from a stationary sensor array located away from an obstacle placed in a potential flow. The ability of neural networks to estimate complex underlying relationships between parameters, in the absence of any explicit mathematical description, is first assessed with two basic potential flow problems: single source/sink identification and doublet detection. Subsequently, we address the inverse problem of identifying an obstacle shape from distant measures of the pressure or velocity field. Using the analytical solution to the forward problem, very large training data sets are generated, allowing us to obtain the synaptic weights by means of a gradient-descent based optimization. The resulting neural network exhibits remarkable effectiveness in predicting unknown obstacle shapes, especially at relatively large distances for which classical linear regression models are completely ineffectual. These results have far-reaching implications for the design and development of artificial passive hydrodynamic sensing technology.
Moiré-fringeless Transparent Conductive Films with a Random Serpentine Network of Medium-Field Electrospun, Chemically Annealed Silver Microfibres
Authors: Shin Dong-Youn , Park Eun-Hye , Kim Ka-Hyun
Published: August 2019

Low-cost flexible transparent conductive films (TCFs) with direct writing of metal grids have been explored as a promising alternative to conventional indium-tin-oxide-based TCFs for future flexible electronics. However, flexible TCFs have raised technical concerns because of their disadvantages, such as low resolution, low productivity, poor optoelectrical performance, poor thermal stability, and adverse moiré fringes, which primarily arise from the superposition of periodic patterns. Herein, a facile and highly productive method to fabricate moiré-fringeless TCFs with good optoelectrical characteristics and excellent thermal stability is presented using a single-pass printed random serpentine network of medium-field electrospun silver microfibres (AgMFs) with a line width of 2.32 ± 0.97 μm by exploiting the random serpentine motion of medium-field electrospinning, enabling moiré-fringeless TCFs. The electrical in-plane anisotropy of the TCFs can be kept well below 110.44 ± 1.26% with the in situ junction formation of the AgMFs in the transverse direction. Combined thermal and chemical annealing of the AgMFs enables high productivity by reducing the thermal annealing time by 40%. The good optoelectrical performance, fair electrical in-plane anisotropy, high productivity, and superior thermal stability of the TCFs with the single-pass printed random serpentine network of medium-field electrospun AgMFs are suitable properties for flexible electronics such as ultra-large digital signage with LEDs.
Long Shape Memory Alloy Tendon-based Soft Robotic Actuators and Implementation as a Soft Gripper
Authors: Lee Ji-Hyeong , Chung Yoon Seop , Rodrigue Hugo
Published: August 2019

Shape memory alloy (SMA) wire-based soft actuators have had their performance limited by the small stroke of the SMA wire embedded within the polymeric matrix. This intrinsically links the bending angle and bending force in a way that made SMA-based soft grippers have relatively poor performance versus other types of soft actuators. In this work, the use of free-sliding SMA wires as tendons for soft actuation is presented that enables large increases in the bending angle and bending force of the actuator by decoupling the length of the matrix and the length of the SMA wires while also allowing for the compact packaging of the driving SMA wires. Bending angles of 400° and tip forces of 0.89 N were achieved by the actuators in this work using a tendon length up to 350 mm. The tendons were integrated as a compact module using bearings that enables the actuator to easily be implemented in various soft gripper configurations. Three fingers were used either in an antagonistic configuration or in a triangular configuration and the gripper was shown to be capable of gripping a wide range of objects weighing up to 1.5 kg and was easily installed on a robotic arm. The maximum pulling force of the gripper was measured to be 30 N.
Occurrence of randomly recombined functional 16S rRNA genes in Thermus thermophilus suggests genetic interoperability and promiscuity of bacterial 16S rRNAs
Authors: Miyazaki Kentaro , Tomariguchi Natsuki
Published: August 2019

Based on the structural complexity of ribosomes, 16S rRNA genes are considered species-specific and hence used for bacterial phylogenetic analysis. However, a growing number of reports suggest the occurrence of horizontal gene transfer, raising genealogical questions. Here we show the genetic interoperability and promiscuity of 16S rRNA in the ribosomes of an extremely thermophilic bacterium, Thermus thermophilus. The gene in this thermophile was systematically replaced with a diverse array of heterologous genes, resulting in the discovery of various genes that supported growth, some of which were from different phyla. Moreover, numerous functional chimeras were spontaneously generated. Remarkably, cold-adapted mutants were obtained carrying chimeric or full-length heterologous genes, indicating that horizontal gene transfer promoted adaptive evolution. The ribosome may well be understood as a patchworked supramolecule comprising patchworked components. We here propose the “random patch model” for ribosomal evolution.
A microscale solid-phase microextraction probe for the in situ analysis of perfluoroalkyl substances and lipids in biological tissues using mass spectrometry
Authors: Yang Yunyun , Deng Jiewei , Liu Yaohui , He Kaili , Xiang Zhangmin , Luan Tiangang
Published: August 2019

An ambient mass spectrometry method for rapid, in situ, and microscale analysis of PFASs and lipids simultaneously in biological tissues for investigation of their biological correlation.
A practical method for rapid screening and quantitative analysis of 130 pesticide residues in herbal medicines based on the Kovats retention index principle: an exemplary study using Panacis quinquefolii radix
Authors: Tan Peng , Wei Xichuan , Zhang Haizhu , Niu Ming , Zhang Dingkun
Published: August 2019

This study has provided a practical analytical method for rapid screening and quantitative analysis of 130 pesticide residues in herbal medicines based on the Kovats retention index.
Photo–nickel dual catalytic benzoylation of aryl bromides
Authors: Schirmer Tobias Emanuel , Wimmer Alexander , Weinzierl Florian Wolfgang Clemens , König Burkhard
Published: August 2019

The dual catalytic arylation of aromatic aldehydes by aryl bromides using UV-irradiation and a nickel catalyst is reported.
A simple strategy for the fabrication of gold-modified single nanopores and its application for miRNA sensing
Authors: Yang Cheng , Wang Hao , Tang Haoran , Zhao Dandan , Li Yongxin
Published: August 2019

A simple strategy was developed for nanopore modification, and was used for miRNA sensing with good sensitivity and selectivity.
Gel to gel transitions by dynamic self-assembly
Authors: Panja Santanu , Adams Dave J.
Published: August 2019

We show how dynamic systems can be used to prepare gels that evolve to give materials with properties that cannot be accessed directly.
Site-selective Ru-catalyzed C–H bond alkenylation with biologically relevant isoindolinones: a case of catalyst performance controlled by subtle stereo-electronic effects of the weak directing group
Authors: Yuan Yu-Chao , Bruneau Christian , Roisnel Thierry , Gramage-Doria Rafael
Published: August 2019

A general regio- and site-selective ruthenium-catalyzed C–H bond alkenylation with the biologically relevant isoindolinone fragment serving as a weak directing group is presented.
A stable high internal phase emulsion fabricated with OSA-modified starch: an improvement in β-carotene stability and bioaccessibility
Authors: Yan Chi , McClements David Julian , Zou Liqiang , Liu Wei
Published: August 2019

A high internal phase emulsion (HIPE) was firstly fabricated with octenyl succinic anhydride modified starch through simple shear dispersion.
Effects of early-life lactoferrin intervention on growth performance, small intestinal function and gut microbiota in suckling piglets
Authors: Hu Ping , Zhao Fangzhou , Zhu Weiyun , Wang Jing
Published: August 2019

The early postnatal stage is a critical period for suckling animals in developing intestinal function and stabilizing gut microbiota.
Loading natural emulsions with nutraceuticals using the pH-driven method: formation & stability of curcumin-loaded soybean oil bodies
Authors: Zheng Bingjing , Zhang Xiaoyun , Lin Helen , McClements David Julian
Published: August 2019

The pH-driven method was used to load curcumin into soymilk. The soymilk had good physical stability but curcumin degradation occurred at higher storage temperatures.
Dual-colored 4,4′,4′′,4′′′-(cyclobutane-1,2,3,4-tetrayl)-tetrabenzoate electrochromic materials with large optical contrast and coloration efficiency
Authors: Zhu Chun-rong , Xie Jia-ping , Mou Hong-rong , Huang Zhen-jie , Tang Qian , Gong Cheng-bin , Fu Xiang-kai
Published: August 2019

This paper reports novel ester-containing electrochromic materials, 4,4′,4′′,4′′′-(cyclobutane-1,2,3,4-tetrayl)tetrabenzoate derivatives, with dual-colored electrochromism, high color contrast and coloration efficiency.
Fast capture and multiplexed detection of short multi-arm DNA stars in solid-state nanopores
Authors: He Liqun , Karau Philipp , Tabard-Cossa Vincent
Published: August 2019

The capture and translocation characteristics of multi-arm DNA star nanostructures are studied to evaluate their potential as advanced labels for improved solid-state nanopore sensing performance.
Tetranuclear Cu(ii)-chiral complexes: synthesis, characterization and biological activity
Authors: Peewasan Krisana , Merkel Marcel P. , Zarschler Kristof , Stephan Holger , Anson Christopher E. , Powell Annie K.
Published: August 2019

A pair of tetranuclear chiral Cu(ii)-Schiff-base complexes were synthesized using enantiomerically pure (S)-H2L and (R)-H2L ligands. These were characterised using single-crystal X-ray diffraction and CD spectroscopy and their biological activity tested.
Bifunctional coatings: coupling an organic adhesion promoter with an anticorrosion inorganic layer
Authors: Doublet Aurélien , Kjellberg Marianne , Jousselme Bruno , Pinault Mathieu , Deniau Guy , Cornut Renaud , Charrier Gaëlle
Published: August 2019

In this work, a multifunctional non-toxic chromium free treatment is proposed.
One-pot pyro synthesis of a nanosized-LiMn2O4/C cathode with enhanced lithium storage properties
Authors: Jo Jeonggeun , Nam Sukyeung , Han Seungmi , Mathew Vinod , Alfaruqi Muhammad Hilmy , Pham Duong Tung , Kim Seokhun , Park Sohyun , Park Sunhyun , Kim Jaekook
Published: August 2019

A simple one-pot polyol-assisted pyro-synthesized LiMn2O4/C cathode demonstrated remarkable lithium cycling stabilities of 86% and 19% and high rate capabilities of 77.5% and 36% at 3.3–4.3 V and 2.5–4.3V, respectively.
Solvent-controlled synthesis of multicolor photoluminescent carbon dots for bioimaging
Authors: Yan Yang , Xia Longyu , Ma Lan
Published: August 2019

The synthesis and bioimaging of multicolor carbon dots from citric acid and urea.
tBuOK-triggered bond formation reactions
Authors: Xu Yulong , Shi Xiaonan , Wu Lipeng
Published: August 2019

Inexpensive and readily available tBuOK can trigger a series of bond formation reactions, including S–S, S–Se, Se–Se, and NN and CN bonds.
Capillary liquid bridge soft lithography for micro-patterning preparation based on SU-8 photoresist templates with special wettability
Authors: Wang Huijie , Li Xiaoxun , Luan Kang , Bai Xilin
Published: August 2019

An interface-induced dewetting assembly strategy based on capillary liquid bridge and SU-8 photoresist templates for patterning organic molecules and nanoparticles.
Pyrene derivatives with two types of substituents at positions 1, 3, 6, and 8 – fad or necessity?
Authors: Zych Dawid , Slodek Aneta
Published: August 2019

1,3,6,8-Tetrasubstituted pyrene derivatives with two types of substituents in various substitution patterns show advantages to their counterparts with only one type of substituent group.
Synthesis of C2-tetrasubstituted indolin-3-ones via Cu-catalyzed oxidative dimerization of 2-aryl indoles and cross-addition with indoles
Authors: Singh Anoop , Vanaparthi Satheeshvarma , Choudhary Sachin , Krishnan Rangan , Kumar Indresh
Published: August 2019

A general protocol for the synthesis of 2,2-disubstituted indolin-3-ones has been developed through self-dimerization of 2-aryl indoles and cross-addition with indoles under mild Cu-catalyzed oxidative conditions with good to high yields.
Particle-resolved lattice Boltzmann simulations of 3-dimensional active turbulence
Authors: Bárdfalvy Dóra , Nordanger Henrik , Nardini Cesare , Morozov Alexander , Stenhammar Joakim
Published: August 2019

The dynamics of active turbulence in a suspension of swimming bacteria is characterised using large-scale lattice Boltzmann simulations of model microswimmers and compared to theoretical predictions.
Supramolecular nanostructures constructed by rod–coil molecular isomers: effect of rod sequences on molecular assembly
Authors: Yang Yuntian , Chen Fengchun , Tian Xizhe , Chen Tie , Wu Lixin , Jin Long Yi
Published: August 2019

Ordered supramolecular nanstructures of rod–coil molecular isomers were created by tuning the sequence of rod segments and altering the type of coil chain in bulk and in aqueous solution.
Enhanced interface reactivity by a nanowrinkled functional layer for intermediate-temperature solid oxide fuel cells
Authors: Lee Jongseo , Hwang Sangyeon , Ahn Minwoo , Choi Mingi , Han Seungwoo , Byun Doyoung , Lee Wonyoung
Published: August 2019

For high-performance intermediate-temperature solid oxide fuel cells (IT-SOFCs), rational design of the interface between the electrode and electrolyte is essential, because interfacial reactivity often dominates the overall performance.
Solvent-free vacuum growth of oriented HKUST-1 thin films
Authors: Han Sungmin , Ciufo Ryan A. , Meyerson Melissa L. , Keitz Benjamin K. , Mullins C. Buddie
Published: August 2019

H3BTC and Cu are sequentially deposited to form highly oriented HKUST-1 thin films under vacuum without the use of solvents.
Achieving high thermoelectric performance through constructing coherent interfaces and building interface potential barriers in n-type Bi2Te3/Bi2Te2.7Se0.3 nanocomposites
Authors: Jabar Bushra , Qin Xiaoying , Li Di , Zhang Jian , Mansoor Adil , Xin Hongxing , Song Chunjun , Huang Lulu
Published: August 2019

Through incorporation of isostructural Bi2Te3 nanoinclusions in n-type Bi2Te2.7Se0.3 we achieve unprecedented energy-conversion efficiency η = 10.5% with record high ZTmax = 1.35.
Theoretical insights into nitrogen fixation on Ti2C and Ti2CO2 in a lithium–nitrogen battery
Authors: Yi Shuaiyu , Liu Guangdong , Liu Zhixiao , Hu Wangyu , Deng Huiqiu
Published: August 2019

Ti2C and Ti2CO2 are promising cathode substrates for N2 fixiation in the Li–N2 battery.
Boosting visible-light-driven hydrogen evolution of covalent organic frameworks through compositing with MoS2: a promising candidate for noble-metal-free photocatalysts
Authors: Gao Meng-Yao , Li Chang-Cheng , Tang Hong-Liang , Sun Xiao-Jun , Dong Hong , Zhang Feng-Ming
Published: August 2019

A series of ultrathin MoS2 nanosheet decorated ketoenamine-based COF (TpPa-1) photocatalysts show excellent photocatalytic activity under visible light irradiation without noble-metal co-catalysts.
Facile, cost-effective plasma synthesis of self-supportive FeSx on Fe foam for efficient electrochemical reduction of N2 under ambient conditions
Authors: Xiong Wei , Guo Zheng , Zhao Shijun , Wang Qian , Xu Qiyong , Wang Xinwei
Published: August 2019

A non-precious, self-supportive FeSx NRR electrocatalyst was synthesized by a simple H2S-plasma treatment on low-cost Fe foam, which shows a remarkable NH3 production rate of 4.13 × 10−10 mol s−1 cm−2 and a high faradaic efficiency of 17.6%.
Flexible, microstructured surfaces using chitin-derived biopolymers
Authors: Pradhan Sayantan , Moore Kathryn M. , Ainslie Kristy M. , Yadavalli Vamsi K.
Published: August 2019

A photocrosslinkable chitin derivative is used to create robust, transparent sheets, and high resolution microstructures via photolithography. The biopolymer can form flexible templates for spatially guiding cells, or in degradable bioelectronics.
Polarons in π-conjugated ladder-type polymers: a broken symmetry density functional description
Authors: Fazzi Daniele , Fabiano Simone , Ruoko Tero-Petri , Meerholz Klaus , Negri Fabrizia
Published: August 2019

Polarons play a role in charge transfer, thermo-electric and redox mechanisms. A detailed description of their multi-configurational wavefunction, structure and properties is provided for a conjugated ladder polymer, at the broken-symmetry DFT level.
Variable impedance fault current bypass circuit for fault arc suppression in distribution network
Authors: Chen Kunyi , Xiao Xianyong
Published: August 2019

The existing fault current bypass circuit to extinguish fault arc does not take into account the influence of the load connected to the fault feeder, which may cause the arc suppression failure because the fault current cannot be reduced. This study proposes a variable impedance fault current bypass circuit for fault arc suppression, which is composed of a checking branch and an adjusting branch. The checking branch is utilised to identify the correctness of fault phase detection needed in establishing the bypass. The adjusting branch can change the impedance of the bypass based on the load connected to the fault feeder to reduce the fault current, and this branch can maintain the recovery voltage of fault location close to zero after the arc was extinguished. The performance of the proposed method, the arc suppression coil, the active method and the traditional bypass method was compared by simulation experiments. The results demonstrate that the performance of the proposed method is not influenced by the load. The proposed method can restrain the fault current and recovery voltage close to zero without being affected by the harmonic components, thus, which is beneficial to extinguish the fault arc without reignition.
Enhancing scene perception using a multispectral fusion of visible–near‐infrared image pair
Authors: Kumar Wahengbam Kanan , Nongmeikapam Kishorjit , Singh Aheibam Dinamani
Published: August 2019

In this study, a method for fusing of visible (or standard RGB) with near‐infrared (NIR) image pair for enhancing a hazy image is proposed. Better image enhancement in terms of contrast, sharpness, increased perception is realised by combining the components from both the spectra. While there are a number of applications that use NIR images, very few combine RGB and NIR information of the same scene taken from two separate imaging devices. Although NIR images are greyscaled in nature, they have intrinsic properties desirable in both colour and visible imagery of a number of scenes. Instances are increased the contrast between sky and clouds; shadowed and non‐shadowed regions; and increased optical depth. These features are in most cases missed by a standard RGB camera and therefore, a fusion of such RGB–NIR image pairs is highly beneficial. The scheme for fusing these image pairs is realised by using a novel, fuzzy clustering algorithm along with wavelet transform so that not only contrast and sharpness are enhanced, but also the chromaticity of the original RGB image is retained. The proposed technique is well demonstrated for various outdoor scenes, and better results are obtained when compared against some of the state‐of‐the‐art techniques proposed recently.
Trilateral convolutional neural network for 3D shape reconstruction of objects from a single depth view
Authors: Rivera Patricio , Valarezo Añazco Edwin , Choi Mun‐Taek , Kim Tae‐Seong
Published: August 2019

In this study, the authors propose a novel three‐dimensional (3D) convolutional neural network for shape reconstruction via a trilateral convolutional neural network (Tri‐CNN) from a single depth view. The proposed approach produces a 3D voxel representation of an object, derived from a partial object surface in a single depth image. The proposed Tri‐CNN combines three dilated convolutions in 3D to expand the convolutional receptive field more efficiently to learn shape reconstructions. To evaluate the proposed Tri‐CNN in terms of reconstruction performance, the publicly available ShapeNet and Big Data for Grasp Planning data sets are utilised. The reconstruction performance was evaluated against four conventional deep learning approaches: namely, fully connected convolutional neural network, baseline CNN, autoencoder CNN, and a generative adversarial reconstruction network. The proposed experimental results show that Tri‐CNN produces superior reconstruction results in terms of intersection over union values and Brier scores with significantly less number of model parameters and memory.
Frequency tuned Minkowski island fractals RHCP antenna optimised for three‐band GPS receiver
Authors: Cao Thanh Nghia , Krzysztofik Wojciech Jan
Published: August 2019

This study presents an antenna design that operates at the three bands of the Global Positioning System (GPS) receiver. The optimised Minkowski island fractal structure combined with the central window is used to design the radiation surface to reduce the size and adjust the resonance frequencies of the antenna. The antenna was designed, and simulated by HFSS computer code, and was fabricated on microwave laminate FR4‐epoxy by fast laser prototyping. The resulting fractal antenna has been operating at three GPS‐bands: fL2 = 1.227, fL5 = 1.176, and fL1 = 1.575 GHz, with return loss S11 < −15 dB, bandwidths BW > 21.5 MHz, for VSWR < 2, at 50‐Ω input impedance, the power gains ∼2.4, 2.85, and 4.2 dBi, and axial ratio of right‐handed circular polarisation 1.5, 03, and 06 dB at fL5, fL2, and fL1, respectively. The simulated and experimental results agree favourable.
Stellar populations of galaxies in the ALHAMBRA survey up toz  ∼  1
Authors: Díaz-García L. A. , Cenarro A. J. , López-Sanjuan C. , Ferreras I. , Fernández-Soto A. , González Delgado R. M. , Márquez I. , Masegosa J. , San Roman I. , Viironen K. , Bonoli S. , Cerviño M. , Moles M. , Cristóbal-Hornillos D. , Alfaro E. , Aparicio-Villegas T. , Benítez N. , Broadhurst T. , Cabrera-Caño J. , Castander F. J. , Cepa J. , Husillos C. , Infante L. , Aguerri J. A. L. , Martínez V. J. , Molino A. , del Olmo A. , Perea J. , Prada F. , Quintana J. M.
Published: August 2019

Aims.We aim at constraining the stellar population properties of quiescent galaxies. These properties reveal how these galaxies evolved and assembled sincez ∼ 1 up to the present time.

Methods.Combining the ALHAMBRA multi-filter photo-spectra with the fitting code for spectral energy distribution MUFFIT (MUlti-Filter FITting), we built a complete catalogue of quiescent galaxies via the dust-corrected stellar mass vs. colour diagram. This catalogue includes stellar population properties, such as age, metallicity, extinction, stellar mass, and photometric redshift, retrieved from the analysis of composited populations based on two independent sets of simple stellar population (SSP) models. We developed and applied a novel methodology to provide, for the first time, the analytic probability distribution functions (PDFs) of mass-weighted age, metallicity, and extinction of quiescent galaxies as a function of redshift and stellar mass. We adopted different star formation histories to discard potential systematics in the analysis.

Results.The number density of quiescent galaxies is found to increase sincez ∼ 1, with a more substantial variation at lower stellar mass. Quiescent galaxies feature extinctionAV <  0.6, with median values in the rangeAV = 0.15–0.3. At increasing stellar mass, quiescent galaxies are older and more metal rich sincez ∼ 1. A detailed analysis of the PDFs reveals that the evolution of quiescent galaxies is not compatible with passive evolution and a slight decrease of 0.1–0.2 dex is hinted at median metallicity. The intrinsic dispersion of the age and metallicity PDFs show a dependence on stellar mass and/or redshift. These results are consistent with both sets of SSP models and assumptions of alternative star formation histories explored. Consequently, the quiescent population must undergo an evolutive pathway including mergers and/or remnants of star formation to reconcile the observed trends, where the “progenitor” bias should also be taken into account.
White light-modulated bipolar resistive switching characteristics of Cu/MoS2 NRs/Pt MIM structure
Authors: Sharma Shubham , Kumar Anuj , Kaur Davinder
Published: August 2019

The present work explores the white light controlled resistive switching functionality of MoS2 nanorods (NRs) by fabricating a metal-insulator-metal stack configuration. The Cu/MoS2 NRs/Pt/Si device demonstrates the reproducible two-state bipolar resistive switching characteristics under both dark and light environments. In the dark condition, the resistive switching behavior of the NR device could be attributed to the metallic path formation/rupture between top and bottom electrodes. Whereas the applied white light causes the lowering of SET and RESET voltages by inducing conducting path formation/rupture via electron trapping/detrapping in sulfur vacancies across the MoS2 NRs. The formation of a conducting path under dark and light illumination conditions is well explained by proposing a conceptual model and analyzing the resistance vs temperature measurements. It is observed that the white light acts as an external tool to modulate the resistive switching behavior of the fabricated NR device. The correlation between the applied light intensity and the SET voltage is also demonstrated. The NR structure of the MoS2 device provides good endurance of 1500 cycles and a long retention time of 103 s at room temperature under light illumination because of straight conducting path formation through NRs. These results demonstrate that the optically active MoS2 NR based devices have potential for next generation tunable nonvolatile resistive random access memory applications with additional functionality such as photosensors and optoelectronic switches.
Comparison of picosecond electron dynamics in isolated and clustered Si quantum dots deposited on a semiconductor surface
Authors: Fukumoto Keiki , Seyhan Ayse , Onda Ken , Oda Shunri , Koshihara Shin-ya
Published: August 2019

Semiconductor quantum dots (QDs) have been widely used in various optoelectronic devices. Extensive studies have been devoted to the application of Si QDs with the aim of realizing various optoelectronic functions based on the modified energy band structure in QDs compared with bulk crystals. Therefore, it is necessary to be able to directly probe the carrier dynamics in single Si QDs of nanoscale dimensions deposited on a SiO2/Si surface, where the environment is compatible with Si-based semiconductor devices. This letter reports the observation and comparison of the ultrafast electron dynamics just after the photoexcitation of isolated and clustered Si QDs on a SiO2/Si surface using time-resolved photoemission electron microscopy with spatial and temporal resolutions of 50 nm and 100 fs, respectively. The detailed structure of QDs was confirmed directly by scanning electron microscopy observations. The results obtained in the present study show that the carrier lifetime in isolated QDs is shorter than that in clustered QDs. This is consistent with the electron–hole interaction in nanospace, significantly modifying the carrier recombination rates.
A misalignment angle error calibration method of underwater acoustic array in strapdown inertial navigation system/ultrashort baseline integrated navigation system based on single transponder mode
Authors: Tong Jinwu , Xu Xiaosu , Zhang Tao , Li Yao , Yao Yiqing , Weng Chengcheng , Hou Lanhua , Zhang Liang
Published: August 2019

The angle misalignment error of a USBL (Ultrashort Baseline) acoustic array is one of the major error sources of the strapdown inertial navigation system/USBL positioning system, which will directly affect the positioning accuracy of the USBL positioning system. For the traditional calibration method cannot accurately estimate the angle misalignment error due to its strict trajectory requirements in the field experiment and the high-precision layout of the transceiver array elements, a new method for estimating the angle misalignment error of a USBL acoustic array based on single transponder and dual-vector reconstruction is studied in this paper. The precondition of USBL misalignment calibration is to locate the underwater transponder accurately. In this paper, the single transponder segmentation iterative long baseline method is used to locate the underwater target transponder. The dual-vector reconstruction method is studied to control the estimation accuracy of USBL misalignment error calibration based on the traditional single transponder method, which provides a theoretical basis for the determination of the iteration times to the USBL angle misalignment error estimation module. The underwater experiment results show that the positioning error could be reduced to less than 1 m after the angle misalignment error compensation. The underwater transponder positioning and the angle misalignment error estimation of USBL could be accomplished in a circle sailing. It is a new method with good performance of high estimation accuracy, simple operation, and easy realization.
Extension of the Einstein molecule method for solid free energy calculation to non-periodic and semi-periodic systems
Authors: Pretti Evan , Mittal Jeetain
Published: August 2019

Free energy calculations on solid phases are important for understanding the phase behavior of various systems. For periodic crystalline solids, the Einstein molecule method can be used to determine the free energy difference between the solid of interest and an ideal crystal for which the free energy can be found analytically. In this work, we show how this method is extensible to systems which are nonperiodic or periodic in some dimensions but not in others. This allows for the calculation of exact absolute free energies of finite-sized crystals having specific shapes and surface geometries. We demonstrate this using the fcc Lennard-Jones solid and also illustrate how surface contributions to free energies can easily be extracted from simulations of this solid in semi-infinite slab geometries. We have developed a software package which interfaces with the LAMMPS molecular dynamics code to perform these calculations.
Diffuse interface immersed boundary method for low Mach number flows with heat transfer in enclosures
Authors: Kumar Mukesh , Natarajan Ganesh
Published: August 2019

A novel diffuse interface immersed boundary (IB) approach in the finite volume framework is developed for non-Boussinesq flows with heat transfer. These flows are characterized by variable density, large temperature differences, nonzero velocity divergence, and low Mach numbers. The present IB methodology assumes that the solid body immersed in the domain is filled with a “virtual” fluid and constructs a unified momentum equation that is solved everywhere in the domain. The unified momentum equation is obtained as a convex combination of the Navier-Stokes equation and the no-slip boundary condition employing the solid volume fraction. The hydrodynamic pressure (p) that drives the flow is obtained by the solution of a variable density Poisson equation that is constructed by assuming that the velocity field inside the solid always remains solenoidal although the velocity divergence is nonzero in the fluid domain. The unified Poisson equation is also solved everywhere in the domain and has source terms that depend on the solid volume fraction, temperature gradients, and the spatially invariant thermodynamic pressure (P) that vanish in the Boussinesq limit. The thermodynamic pressure in closed domains follows from the principle of global mass conservation and is used to determine the density field everywhere in the domain except inside the solid where the density remains constant. Numerical simulations are carried out for natural and mixed convective flows in enclosures with stationary and moving heated bodies encompassing both Boussinesq and strongly non-Boussinesq flow regimes. The results of these investigations show that the local Nusselt number distribution over the body surface is oscillatory particularly when grid lines are not aligned with the surface of the body. However, the proposed approach can reasonably accurately compute the average heat transfer in both Boussinesq and non-Boussinesq flows. Investigations show that the heat transfer is significantly enhanced in the non-Boussinesq regime as compared to the Boussinesq regime. A comparison of results from the present approach with those obtained using a body-fitted finite volume solver for stationary bodies demonstrates that the proposed IB approach can compute the flow dynamics quite accurately even on Cartesian meshes that do not conform to the geometry. The IB approach presented herein is a generic approach for quasi-incompressible flows and may be applied to other low Mach number flows such as mixing and reacting flows.
Electrokinetic instability in microchannel viscoelastic fluid flows with conductivity gradients
Authors: Song Le , Jagdale Purva , Yu Liandong , Liu Zhijian , Li Di , Zhang Cheng , Xuan Xiangchun
Published: August 2019

Electrokinetic instability (EKI) is a flow instability that occurs in electric field-mediated microfluidic applications. It can be harnessed to enhance sample mixing or particle trapping but has to be avoided in particle separation. Current studies on EKI have been focused primarily on the flow of Newtonian fluids. However, many of the chemical and biological solutions exhibit non-Newtonian characteristics. This work presents the first experimental study of the EKI in viscoelastic fluid flows with conductivity gradients through a T-shaped microchannel. We find that the addition of polyethylene oxide (PEO) polymer into Newtonian buffer solutions alters the threshold electric field for the onset of EKI. Moreover, the speed and temporal frequency of the instability waves are significantly different from those in the pure buffer solutions. We develop a three-dimensional preliminary numerical model in COMSOL, which considers the increased viscosity and conductivity as well as the suppressed electroosmotic flow of the buffer-based PEO solutions. The numerically predicted threshold electric field and wave parameters compare favorably with the experimental data except at the highest PEO concentration. We attribute this deviation to the neglect of fluid elasticity effect in the current model that increases with the PEO concentration.
Thermoelectric characterization of ZnSb by first-principles method
Authors: Maurya V. , Galav K. L. , Sharma G. , Joshi K. B.
Published: August 2019

The thermoelectric properties of semiconducting compound ZnSb are studied using crystalline orbitals program based on the periodic linear combination of atomic orbitals method. The calculations are done under the framework of density functional theory. We calculate the electronic band structure and the density of states. The k-space eigenvalues are coupled with Boltzmann transport equations to calculate transport coefficients such as the Seebeck coefficient, power factor and electronic thermal conductivity under the constant relaxation time and the rigid band approximations. Effect of the scissor correction on the transport coefficients is examined. We have found that ZnSb behaves as n-type thermoelectric. A comparison with available measurements is done and a good agreement is found. The thermoelectric performance is compared with other materials by means of the electronic fitness function which suggests ZnSb to be a good thermoelectric material.
The stability and oxidation of supported atomic-size Cu catalysts in reactive environments
Authors: Iyemperumal Satish Kumar , Fenton Thomas G. , Gillingham Samantha L. , Carl Alexander D. , Grimm Ronald L. , Li Gonghu , Deskins N. Aaron
Published: August 2019

Atomic-scale species (atoms and clusters) have attracted much attention as potential highly active catalysts. Synthesizing such catalysts that may be stable under synthesis or reaction conditions is a challenge. In this work, we used density functional theory to model the growth of Cu clusters on the TiO2 support, including sintering and oxidation. Oxidation of supported Cu was preferred over sintering due to metal-support interactions. Ab initio thermodynamics calculations showed that O2 readily oxidized most clusters, while H2O was a mild oxidant. CO2 did not oxidize any clusters at relevant temperatures. Thermodynamics would suggest that oxidation of Cu atoms/clusters would readily occur, but kinetic analysis suggested otherwise. O2 adsorption was weak over the TiO2 surface, as well as most oxidized clusters. O2 dissociation barriers were low over nonoxidized Cu clusters, but quite high (1.88 eV) over single Cu atoms. Our results suggest that lone Cu atoms are stabilized on the surface, due to a high diffusion barrier (necessary for sintering) and a high O2 dissociation barrier (necessary for oxidation). We performed experiments that indeed support the premise that lone Cu atoms occur on the surface. Cu species were deposited on TiO2, and any Cu2+ species (indicative of oxidized Cu clusters) were removed after thermal treatment in various environments. Only Cu0 and Cu1+ species existed after thermal treatment. Lone adsorbed Cu atoms had a +1 oxidation state. Combined, our calculations and experiments indicate that Cu1+ species (lone adsorbed Cu atoms) are dominant. The kinetics of oxidation/diffusion rather than thermodynamics limits the growth/oxidation of Cu. In summary, we show that metal-support interactions are key for synthesizing stable atomic-scale catalysts, since they can strongly influence key processes such as diffusion/oxidation.
Dependence of plasma current on object condition in atmospheric pressure non-thermal equilibrium argon plasma
Authors: Yambe Kiyoyuki , Kuramoto Naoya , Inagaki Yusuke
Published: August 2019

The dependence of the plasma plume current on the object condition is investigated by atmospheric pressure non-thermal equilibrium argon plasma. When processing with plasma, the flow of plasma current changes depending on the condition of the object. In the case of metal object with grounded condition, the plasma current was independent of the surface area and electrical conductivity of the metal object. While, in the case of metal object with floating condition, the plasma current was dependent on the surface area of the metal object, but not on the electrical conductivity of the metal object. When an object is grounded, the closed circuit is fixed with plasma, object, and ground-line, and then the current flow follows Ohm’s law. Because the ground-line is longer than the plasma plume length and the scale length of the object, the plasma current is independent of the characteristics of the metal object. When the object is in a floating condition, the divergence of the charge stored in the object to the atmosphere depends on the surface area of the object because it follows Gauss’s law.
The entropic bond in colloidal crystals
Authors: Harper Eric S. , van Anders Greg , Glotzer Sharon C.
Published: August 2019

Significance

Chemical bonding, in various forms, is integral to the structure of matter and the function of living systems. However, what are the minimal requirements to form a bond? We show that classical systems governed solely by entropy exhibit unconventional, entropy-mediated bonding. We also show the description of such systems in terms of bonds provides better understanding for the design of materials from nanoscale building blocks. Our results suggest well-defined analogs of chemical bonds exist in a broad range of unconventional systems.
EglN3 hydroxylase stabilizes BIM-EL linking VHL type 2C mutations to pheochromocytoma pathogenesis and chemotherapy resistance
Authors: Li Shuijie , Rodriguez Javier , Li Wenyu , Bullova Petra , Fell Stuart M. , Surova Olga , Westerlund Isabelle , Topcic Danijal , Bergsland Maria , Stenman Adam , Muhr Jonas , Nistér Monica , Holmberg Johan , Juhlin C. Christofer , Larsson Catharina , von Kriegsheim Alex , Kaelin William G. , Schlisio Susanne
Published: August 2019

Significance

Different mutations of the von Hippel–Lindau (VHL) tumor suppressor gene cause different subtypes of VHL hereditary cancer syndrome. Dysregulation of VHL’s canonical substrate, HIFα, cannot fully explain the complex genotype/phenotype manifestation within VHL disease. We describe an oxygen-sensitive function of VHL that regulates hydroxylated BIM-EL protein stability. Type 2C VHL mutants, which cause pheochromocytoma and paraganglioma (PCC/PGL) despite repressing HIFα, destabilize BIM-EL. Other genetic mutations linked to PCC/PGL, similar to loss of BIM-EL, protect from apoptosis upon nerve growth factor withdrawal. Dysregulation of BIM-EL might therefore contribute to the pathogenesis of VHL-related PCC/PGL. Loss of BIM-EL expression can lead to chemotherapy resistance in other VHL-related neoplasms and renders clear cell renal cell carcinoma cells insensitive to cisplatin.
Contrasting evolution of virulence and replication rate in an emerging bacterial pathogen
Authors: Tardy Luc , Giraudeau Mathieu , Hill Geoffrey E. , McGraw Kevin J. , Bonneaud Camille
Published: August 2019

Host resistance through immune clearance is predicted to favor pathogens that are able to transmit faster and are hence more virulent. Increasing pathogen virulence is, in turn, typically assumed to be mediated by increasing replication rates. However, experiments designed to test how pathogen virulence and replication rates evolve in response to increasing host resistance, as well as the relationship between the two, are rare and lacking for naturally evolving host–pathogen interactions. We inoculated 55 isolates of
Mycoplasma gallisepticum
, collected over 20 y from outbreak, into house finches (
Haemorhous mexicanus
) from disease-unexposed populations, which have not evolved protective immunity to
M. gallisepticum
. We show using 3 different metrics of virulence (body mass loss, symptom severity, and putative mortality rate) that virulence has increased linearly over >150,000 bacterial generations since outbreak (1994 to 2015). By contrast, while replication rates increased from outbreak to the initial spread of resistance (1994 to 2004), no further increases have occurred subsequently (2007 to 2015). Finally, as a consequence, we found that any potential mediating effect of replication rate on virulence evolution was restricted to the period when host resistance was initially increasing in the population. Taken together, our results show that pathogen virulence and replication rates can evolve independently, particularly after the initial spread of host resistance. We hypothesize that the evolution of pathogen virulence can be driven primarily by processes such as immune manipulation after resistance spreads in host populations.
Building a synthetic mechanosensitive signaling pathway in compartmentalized artificial cells
Authors: Hindley James W. , Zheleva Daniela G. , Elani Yuval , Charalambous Kalypso , Barter Laura M. C. , Booth Paula J. , Bevan Charlotte L. , Law Robert V. , Ces Oscar
Published: August 2019

Significance

In nature, an external input is translated by cellular machinery into a downstream effect through signaling pathways, enabling cells to respond to their environment. Bottom-up synthetic biology aims to re-create cellular organization and function through the creation of “artificial cells” (ACs) through molecular self-assembly. Although the construction of new signaling pathways will enable increasingly responsive ACs, this area is undeveloped; here, we show that multicompartment lipid vesicles are an ideal framework to build a pathway not found in nature. External calcium ions activate internal protein communication, leading to control of cell fluorescence. This highlights the potential of ACs for design and construction of synthetic pathways difficult to reconstitute in existing cells, leading to development of environment-responsive molecular machines in biotechnology.
Specific targeting of CD163+ TAMs mobilizes inflammatory monocytes and promotes T cell–mediated tumor regression
Authors: Etzerodt Anders , Tsalkitzi Kyriaki , Maniecki Maciej , Damsky William , Delfini Marcello , Baudoin Elodie , Moulin Morgane , Bosenberg Marcus , Graversen Jonas Heilskov , Auphan-Anezin Nathalie , Moestrup Søren Kragh , Lawrence Toby
Published: August 2019

Tumor-associated macrophages (TAMs) play critical roles in tumor progression but are also capable of contributing to antitumor immunity. Recent studies have revealed an unprecedented heterogeneity among TAMs in both human cancer and experimental models. Nevertheless, we still understand little about the contribution of different TAM subsets to tumor progression. Here, we demonstrate that CD163-expressing TAMs specifically maintain immune suppression in an experimental model of melanoma that is resistant to anti–PD-1 checkpoint therapy. Specific depletion of the CD163+ macrophages results in a massive infiltration of activated T cells and tumor regression. Importantly, the infiltration of cytotoxic T cells was accompanied by the mobilization of inflammatory monocytes that significantly contributed to tumor regression. Thus, the specific targeting of CD163+ TAMs reeducates the tumor immune microenvironment and promotes both myeloid and T cell–mediated antitumor immunity, illustrating the importance of selective targeting of tumor-associated myeloid cells in a therapeutic context.
Electrically controllable connection and power transfer by electroadhesion
Authors: Guo Jianglong , Xiang Chaoqun , Rossiter Jonathan
Published: August 2019

Reconfigurable smart structures and robots require interconnects that enable the transfer of forces, power and data from one modular element to another. This is typically achieved through magnetic coupling, mechanical clips and male–female electrical contacts. In lightweight structures however, these methods are impractical due to weight and complexity. In this work we present an electroadhesive coupling (EAC) controllable interfacial connection for joining lightweight modular components, which enable simultaneous mechanical joining and electrical pass-through connections for power and communication. Active adhesion and power transfer are realized by electroadhesion (EA) using conducting electrodes on lightweight materials such as papers. We present the underlying EAC concept, materials and structures, and demonstrate this new approach using origami and kirigami structures to fabricate a modular EAC bridge and a modular EAC cuboid structural interconnection system. These novel structures have the potential for application in lightweight robotics, space systems, deployable and self-assembling and self-disassembling systems.
Numerical analysis of low-tech overshot water wheel for off grid purpose
Authors: Bachan Animesh , Ghimire Nirajan , Eisner Johannes , Chitrakar Sailesh , Prasad Neopane Hari
Published: August 2019

The rural areas of Nepal comprise of many rivers and rivulets which is not properly utilized till yet. In Nepal, the focus is set on overshot waterwheel due to its applicability in low discharge and low head sites with high efficiency. This paper presents the numerical analysis of a low-tech overshot wheel. Simulation of overshot wheel is done at flow rate, and horizontal distance and vertical clearance of the inlet canal. It is found that the water wheel generates higher power at the condition when the flow rate is 25 kg/s, horizontal distance between chute and wheel is 20 cm and the vertical clearance is 2 cm.