bluuebunny/crossref_metadata_2025 huggingface dataset:
Allelopathic Activity of Some Medicinal Plants against Erwinia carotovora
Authors: Hamad Hamida M. E. , Al-Ailla Ahlam A. K.
Published: May 2019

Many medicinal plants, exhibit allelopathy to biological management of plant pathogens by reducing their regeneration. This process involving secondary metabolites produced by plant influence the growth and development of agricultural and biological system. This research was to determine the allelopathic potential of aqueous extracts of different medicinal species (Artemisia herba alba, Pistacia atlantica and Juniperus phoenicea) against plant pathogenic bacteria (Erwinia carotovora subsp. Carotovora) in comparison to the antibiotic Streptomycin (positive control). Effect of water extracts evaluated for different concentrations of different extracts for each plant studied was examined under laboratory conditions in petri dishes. The results showed that all the extracts significantly inhibited growth of tested bacteria. The differences in their inhibition depend on to the type of plant and concentration of extract. However, Artemisia herba alba extracts had greater inhibitory potential. Based on the study results, aqueous extracts of three plant species (A. herba alba, P. atlantica and J. phoenicea) showed a negative allelopathic effects on plant pathogenic bacteria (Erwinia carotovora subsp. Carotovora).
Prognostic Value of Urine Albumen/Creatinin Ratio in Sepsis in Critical Care Patients
Authors: Rizk Yousry El Saied , Rahman Ahmed Hamdy Abd El , Moneim Abdel Moneim Ahmed Abdel , Amer Waleed Ahmed Ali
Published: May 2019

Several scoring systems were developed for prognosis and outcome prediction in sepsis. This study aims to evaluate the urinary albumin/creatinine ratio (ACR) as a prognostic predictor in sepsis. The study included 50 adult septic patients in a prospective observational study. Study excluded patients with preexisting chronic kidney disease or diabetes mellitus. After clinical evaluation, urine spot samples were collected on admission and 24 h later for ACR1 and ACR2. Admission APACHE IV score and the highest recorded SOFA score of their daily estimation were considered. This study also evaluated the need for mechanical ventilation, inotropic or vasoactive support, renal replacement therapy (RRT), and in-hospital mortality. In a population with Mean±SD 51.4±16.3 (19-82) year old with 34 (68%) males, we found that the ACR2 is correlated with both APACHE IV and SOFA scores (P <0.001). ACR2 was higher in patients who needed mechanical ventilation and inotropic or vasoactive support [121(21-235) and 166.5(89-235) mg/g respectively] compared to [49(22-120) and 56.5(21-211) mg/g], P <0.001 in both. ΔACR, ACR2, increasing ACR and APACHE IV were predictors of mortality. The AUC for mortality prediction was largest for ΔACR (1), increasing ACR (0.985), ACR2 (0.963) then APACHE IV (0.90). ∆ACR and ACR2 of 91.5 mg/g and -22 was 88.2% & 100% sensitive and 90.9% & 100% specific respectively to predict mortality. We concluded that the urinary ACR might be used as a simple test for prognosis and mortality prediction in sepsis.
Maize Response to Leguminous Biomass Composted with Phosphate Rocks in the Northern Zone of Tanzania
Authors: Shitindi Mawazo , Kpomblekou-A Kokoasse , McElhenney Wendell H. , Ankumah Ramble , Semoka Johnson , Bekunda Mateete , Bonsi Conrad
Published: May 2019

A study was conducted to evaluate maize response to leguminous biomass composted with phosphate rocks (PRs) in a split plot design. Field experiments were conducted at Wang’waray Farmers Training Center (F.T.C) located in Babati District of Manyara region in the Northern zone of Tanzania between December 2013 and June 2015. Three leguminous (Crotalaria juncea, Lablab purpureus and Mucuna pruriens) strips were cultivated in 2013/14 to produce a biomass which was harvested at flowering to early podding stage and air dried.  Air-dry biomass was composted with PRs from Minjingu (medium reactive PR) and Panda Hill (low reactive PR). Maize response to different treatments was evaluated across the field strips in 2014/15 season. The strips previously used to produce leguminous biomass were used as main plots and each strip was divided into seven subplots receiving different treatments at random. A medium term maize variety SC. 627 was used as a test crop. Average maize grain yields obtained from Crotalaria, Lablab and Mucuna strips reached 5.3, 4.5 and 4.0 t ha-1, respectively and were statistically different (P=.05). Application of Minjingu or Panda Hill PR alone didn’t increase maize grain yield above the control while Minjingu PR applied with urea or composted with biomass increased maize grain yield by 2.40 and 1.58 t ha-1, respectively above the control. Application of Panda Hill PR with urea or composted with biomass increased grain yield by 1.20 and 1.06 t ha-1, respectively above the control. The observed differences (0.82 and 0.14 t ha-1) were not statistically significant indicating that biomass composted with PR was as effective as the PR applied with urea.
Intracellular accumulation of staphylopine impairs the fitness of Staphylococcus aureus cntE mutant
Authors: Chen Chunhui , Hooper David C.
Published: May 2019

Staphylococcus aureus exports staphylopine (StP), a broad‐spectrum metallophore, via the CntE efflux pump. Here, the mechanism of the fitness defect in the ΔcntE mutant under metal depletion was investigated. Deletion of the StP exporter CntE results in a substantial growth defect, and disrupting the StP biosynthesis gene cntL restores growth of the ΔcntE mutant in metal‐depleted media. High‐resolution mass spectrometry revealed cytoplasmic accumulation of StP and the absence of extracellular StP in the ΔcntE mutant. The fitness defect of the ΔcntE mutant in mouse subcutaneous abscesses is largely due to StP accumulation. Expression of StP biosynthesis genes are upregulated in the ΔcntE mutant under metal starvation induction. In conclusion, failure to efflux StP results in intracellular StP accumulation and substantially impairs the fitness of S. aureus.
Quality evaluation of image‐based iterative reconstruction for CT: Comparison with hybrid iterative reconstruction
Authors: Kawashima Hiroki , Ichikawa Katsuhiro , Matsubara Kosuke , Nagata Hiroji , Takata Tadanori , Kobayashi Satoshi
Published: May 2019

The purpose of this study is to evaluate the physical image quality of a commercially available image‐based iterative reconstruction (IIR) system for two object contrasts to resemble a soft tissue (60 HU) and an enhanced vessel (270 HU), and compare the results with those of filtered back projection (FBP) and iterative reconstruction (IR). A 192‐slice computed tomography (CT) scanner was used for data acquisitions. IIR images were processed from the FBP images. Task‐based in‐plane transfer function (TTF) and slice sensitivity profile (SSPtask) were measured from rod objects inside of a 25‐cm diameter water phantom at four dose levels (2.5, 5, 10, and 20 mGy). Noise power spectrum (NPS) was measured from the water‐only part. System performance (SP) function was calculated as TTF2/NPS over FBP, IR, and IIR for comparison. In addition, an image subtraction was performed using images of rod objects, a bar‐pattern phantom, and a clinical abdomen case to observe the noise reduction performance of IIR. As a results, IIR mostly preserved TTF and SSPtask of FBP, whereas IR exhibited enhanced TTF at 10 and 20 mGy for 60 HU contrast and at all doses for 270 HU contrast. SP of IIR at 2.5, 5, 10 mGy (half doses) were similar to those of FBP at 5, 10, 20 mGy, respectively. IR exhibited enhanced SP at medium to high frequencies. The subtracted images showed weak remained edge signals in the bar‐pattern and abdominal images. In conclusion, IIR uniformly improved the task‐based image quality of FBP over the entire frequency range, whereas IR improved the characteristics over medium to high frequencies. The dose reduction potential of IIR estimated from SP is approximately 50%, when allowing the slight signal reductions.
The pedunculopontine region and breathing in Parkinson's disease
Authors: Hyam Jonathan A. , Wang Shouyan , Roy Holly , Moosavi Shakeeb H. , Martin Sean C. , Brittain John Stuart , Coyne Terry , Silburn Peter , Aziz Tipu Z. , Green Alexander L.
Published: May 2019

Objective

Respiratory abnormalities such as upper airway obstruction are common in Parkinson's disease (PD) and are an important cause of mortality and morbidity. We tested the effect of pedunculopontine region (PPNr) stimulation on respiratory maneuvers in human participants with PD, and separately recorded PPNr neural activity reflected in the local field potential (LFP) during these maneuvers.

Methods

Nine patients with deep brain stimulation electrodes in PPNr, and seven in globus pallidus interna (GPi) were studied during trials of maximal inspiration followed by forced expiration with stimulation OFF and ON. Local field potentials (LFPs) were recorded in the unstimulated condition.

Results

PEFR increased from 6.41 ± 0.63 L/sec in the OFF stimulation state to 7.5 L ± 0.65 L/sec in the ON stimulation state (z = −2.666, df = 8, P = 0.024). Percentage improvement in PEFR was strongly correlated with proximity of the stimulated electrode contact to the mesencephalic locomotor region in the rostral PPN (r = 0.814, n = 9, P = 0.008). Mean PPNr LFP power increased within the alpha band (7–11 Hz) during forced respiratory maneuvers (1.63 ± 0.16 μV2/Hz) compared to resting breathing (0.77 ± 0.16 μV2/Hz; z = −2.197, df = 6, P = 0.028). No changes in alpha activity or spirometric indices were seen with GPi recording or stimulation. Percentage improvement in PEFR was strongly positively correlated with increase in alpha power (r = 0.653, n = 14 (7 PPNr patients recorded bilaterally), P = 0.0096).

Interpretation

PPNr stimulation in PD improves indices of upper airway function. Increased alpha‐band activity is seen within the PPNr during forced respiratory maneuvers. Our findings suggest a link between the PPNr and respiratory performance in PD.
Etiologic links between environmental and lifestyle factors and Essential tremor
Authors: Ong Yi‐Lin , Deng Xiao , Tan Eng‐King
Published: May 2019

Essential tremor (ET) is one of the most common adult movement disorders, characterized by clinical tremor and other nonmotor symptoms. It is a progressive disease that shares features with other neurodegenerative diseases. ET is a complex disease with both genetic and environmental underpinnings. While genetic forms of ET are well recognized, the role of environmental and lifestyle factors in ET has been debated. Studies suggest that exposure to neurotoxic compounds such as β‐carboline alkaloids and ethanol are potential risk factors for ET, while antioxidant intake may be protective. In addition, smoking acts as a protective factor in ET, parallel to its effects in other neurological diseases. New evidence points to pesticide and lead exposure as potential risk factors. There is growing evidence to suggest that environmental and lifestyle factors play a role in ET but additional research is needed in order to completely understand their cause and effect association. There is also a need for larger case‐control and prospective cohort studies across different populations to further evaluate the etiological importance of these factors in ET.
Adaptive switching control based on limited multiple models
Authors: Yin Qitian , Wang Mao , Zhao Wei
Published: May 2019

In this paper, the limited multiple models system identification scheme with third‐level adaptation is proposed to build the virtual identification model for the control of the closed‐loop system. First, the dynamical switching identification models subbank is constructed based on the performance index. Next, the virtual identification model is build through the combination of the identification models in the dynamical switching subbank. Then, the combination proportion of the models is adaptively tuning with the third‐level adaptation. The main contribution of this paper is that the proposed dynamical system identification method can overcome system resources waste of the multiple models switching with second‐level adaptation, and it does not require that all of the identification models combine directly. Finally, the simulation is provided to illustrate its effectiveness.
Algorithms of adaptive tracking of unknown multisinusoidal signals in linear systems with arbitrary input delay
Authors: Gerasimov Dmitry N. , Miliushin Aleksandr S. , Nikiforov Vladimir O.
Published: May 2019

The problem of adaptive tracking control is addressed for the class of linear time‐invariant plants with known parameters and arbitrary known input delay. The reference signal is a priori unknown and is represented by a sum of biased harmonics with unknown amplitudes, frequencies, and phases. Asymptotic tracking is provided by predictive adjustable control with parameters generated by one of three designed adaptation algorithms. The first algorithm is based on a gradient scheme and ensures zero steady‐state tracking error with all signals bounded. The other two algorithms additionally involve the scheme with fast parametric convergence improving the closed‐loop system performance. In all the algorithms, the problem of delay compensation is resolved by special augmentation of tracking error. The adjustable control law proposed do not require identification of the reference signal parameters.
A Novel Strategy for the Selection of Polysulfide Adsorbents Toward High‐Performance Lithium‐Sulfur Batteries
Authors: Shang Xiaonan , Qin Tianfeng , Guo Pengqian , Sun Kai , Su Hao , Tao Kun , He Deyan
Published: May 2019

Selection of polysulfide adsorbents for most lithium‐sulfur batteries (LSBs) has only one purpose, which is to suppress the shuttle effect. However, addition of the polysulfides adsorbents inevitably reduces the energy density of LSBs. In this article, a new idea to select a polar cathode material whose discharge–charge voltage coincides with sulfur is proposed. It can adsorb polysulfides and provides part of capacity in the discharge of LSBs. TiO2 is used as an example to prove the feasibility of such an idea, and prepares a sandwich structure cathode via a simple method. In situ X‐ray diffraction is carried out to directly monitor the structural changes of the sandwich‐structured cathode during the discharge–charge processes. The experimental data verify the idea and the work provides a new strategy for the selection of polysulfide adsorbents in the future.
Plasmonic Lithography: Recent Progress
Authors: Hong Fan , Blaikie Richard
Published: May 2019

Plasmonic lithography has received extensive attention as both a potential candidate for next generation lithography and as an interesting testbed to test the fundamental resolution limits of optical imaging and patterning. Owing to the utilization of the otherwise lost evanescent near fields containing high frequency information, surface plasmon‐based lithographic techniques can break the diffraction limit in conventional photolithography; resolution down to approximately 20 nm using visible light has been experimentally demonstrated, and theoretical studies have analyzed methods that have the potential for creating nanopatterns with sub‐10 nm resolution. This paper reviews the research progress and various modalities of plasmonic lithography, addresses current obstacles and problems, and provides an outlook for practical application.
Plasmonic Near‐Complete Optical Absorption and Its Applications
Authors: Ng Charlene , Wesemann Lukas , Panchenko Evgeniy , Song Jingchao , Davis Timothy J. , Roberts Ann , Gómez Daniel E.
Published: May 2019

Near‐complete absorption of light has the potential to underpin advances in photodetection, advanced chemistry, coloration of materials, and energy. This review paper reports recent progress on the development of metasurfaces and thin film structures that produce strong absorption bands in the visible and longer wavelength regions of the electromagnetic spectrum, due in part to the excitation of plasmonic resonances. Proof‐of‐concept demonstrations are discussed for applications of these in chemical sensing, the generation of structural color, the creation of optoelectronic devices, and photocatalysis. Emerging future applications are also discussed.
Printing of Highly Vivid Structural Colors on Metal Substrates with a Metal‐Dielectric Double Layer
Authors: Seo Minseok , Kim Jaeyong , Oh Harim , Kim Man , Baek In Uk , Choi Kwang‐Deok , Byun Ji Young , Lee Myeongkyu
Published: May 2019

The aesthetic functions of metals have attracted increasing attention, and their colorization is of scientific and technological significance. This study demonstrates that vivid structural colors can be produced on stainless steel and Al, which are two of the most commonly used metals. It is well known that a transparent dielectric film coated onto a substrate exhibits a rippled spectrum consisting of alternating reflectance minima and maxima due to multibeam interference, making it appear colored. However, such a film does not produce strong colors on a highly reflective metallic substrate, because the resulting interference ripple has small amplitudes. Herein, very vivid colors are generated by coating a thin metal layer over a dielectric film, where the metal layer adjusts the amount of light incident into the dielectric and strengthens the interference effect. The hue and saturation of the produced colors are controllable by changing the thicknesses of the dielectric and metallic layers. Additionally, color images are printed by locally controlling the layer thicknesses. This method has potential for various applications ranging from surface decoration and visual arts to optical filters and perfect absorbers.
Shining Light on Liquid Crystal Polymer Networks: Preparing, Reconfiguring, and Driving Soft Actuators
Authors: Jiang Zhi‐Chao , Xiao Yao‐Yu , Zhao Yue
Published: May 2019

Soft actuators based on liquid crystal polymer networks (LCNs) have emerged as an exciting research topic due to many envisioned applications in areas such as soft robotics and self‐regulating devices. The infatuation stems from the amazing ability of LCNs to display reversible, large amplitude, and complex shape change as well as locomotion upon a stimuli‐triggered phase transition of mesogens between ordered liquid crystal and disordered isotropic state. Among the various stimuli, light arguably is the most attractive choice. Light can easily be adjusted for its wavelength, intensity, or polarization, structured by means of photomasks or interference patterns, and applied to a target remotely and with high spatiotemporal resolution. Indeed, much research effort is dedicated to LCN actuators that are designed to respond to light in many ways, with light being used not only as an external energy source to drive the shape changes or motion of LCN actuators, but also as a versatile tool in their fabrication and reconfiguration. In this Review, recent achievements are highlighted, a number of important issues are discussed, and critical analysis on the use of light in making, reconfiguring, and driving LCN actuators is provided.
Gallium Polymorphs: Phase‐Dependent Plasmonics
Authors: Gutiérrez Yael , Losurdo Maria , García‐Fernández Pablo , Sainz de la Maza Marta , González Francisco , Brown April S. , Everitt Henry O. , Junquera Javier , Moreno Fernando
Published: May 2019

Interest in gallium (Ga) is growing rapidly, thanks in part to its wide spectral tunability and its intriguing temperature‐dependent polymorphism. In order to exploit and control phase‐change plasmonics in the liquid and solid phases of Ga, an accurate understanding of the dielectric functions for each Ga phase is needed. A comprehensive analysis of the interdependence of the crystal structure, band structure, and dielectric function of the several Ga phases (liquid, α, β, γ, δ) is presented, showing that the selective presence of flat bands in the vicinity of the Fermi energy is crucial to understand the metallicity of each phase. The dielectric function obtained through first principles calculations is compared with experimental measurements obtained by spectroscopic ellipsometry. Cooling liquid Ga always produces a mixture of phases, and how the volume fraction of each phase may be deduced from these pure phase dielectric functions and an analysis of the measured spectra using a Bruggeman effective medium approximation is demonstrated. Figures of merit are presented, and applications of Ga polymorphism are discussed for propagating and localized surface plasmon resonances in Ga thin films and nanostructures, respectively. This research can have important implications on the phase change control for plasmonics/photonic applications with gallium.
Mechanism‐Guided Design of Highly Efficient Protein Secretion and Lipid Conversion for Biomanufacturing and Biorefining
Authors: Xie Shangxian , Sun Su , Lin Furong , Li Muzi , Pu Yunqiao , Cheng Yanbing , Xu Bing , Liu Zhihua , da Costa Sousa Leonardo , Dale Bruce E. , Ragauskas Arthur J. , Dai Susie Y. , Yuan Joshua S.
Published: May 2019

Bacterial protein secretion represents a significant challenge in biotechnology, which is essential for the cost‐effective production of therapeutics, enzymes, and other functional proteins. Here, it is demonstrated that proteomics‐guided engineering of transcription, translation, secretion, and folding of ligninolytic laccase balances the process, minimizes the toxicity, and enables efficient heterologous secretion with a total protein yield of 13.7 g L−1. The secretory laccase complements the biochemical limits on lignin depolymerization well in Rhodococcus opacus PD630. Further proteomics analysis reveals the mechanisms for the oleaginous phenotype of R. opacus PD630, where a distinct multiunit fatty acid synthase I drives the carbon partition to storage lipid. The discovery guides the design of efficient lipid conversion from lignin and carbohydrate. The proteomics‐guided integration of laccase‐secretion and lipid production modules enables a high titer in converting lignin‐enriched biorefinery waste to lipid. The fundamental mechanisms, engineering components, and design principle can empower transformative platforms for biomanufacturing and biorefining.
Site‐Specific Wetting of Iron Nanocubes by Gold Atoms in Gas‐Phase Synthesis
Authors: Vernieres Jerome , Steinhauer Stephan , Zhao Junlei , Grammatikopoulos Panagiotis , Ferrando Riccardo , Nordlund Kai , Djurabekova Flyura , Sowwan Mukhles
Published: May 2019

A key challenge in nanotechnology is the rational design of multicomponent materials that beat the properties of their elemental counterparts. At the same time, when considering the material composition of such hybrid nanostructures and the fabrication process to obtain them, one should favor the use of nontoxic, abundant elements in view of the limited availability of critical metals and sustainability. Cluster beam deposition offers a solvent‐ and, therefore, effluent‐free physical synthesis method to achieve nanomaterials with tailored characteristics. However, the simultaneous control of size, shape, and elemental distribution within a single nanoparticle in a small‐size regime (sub‐10 nm) is still a major challenge, equally limiting physical and chemical approaches. Here, a single‐step nanoparticle fabrication method based on magnetron‐sputtering inert‐gas condensation is reported, which relies on selective wetting of specific surface sites on precondensed iron nanocubes by gold atoms. Using a newly developed Fe–Au interatomic potential, the growth mechanism is decomposed into a multistage model implemented in a molecular dynamics simulation framework. The importance of growth kinetics is emphasized through differences between structures obtained either experimentally or computationally, and thermodynamically favorable configurations determined via global optimization techniques. These results provide a roadmap for engineering complex nanoalloys toward targeted applications.
Tuning Ultrafast Photoinduced Strain in Ferroelectric‐Based Devices
Authors: Matzen Sylvia , Guillemot Loïc , Maroutian Thomas , Patel Sheena K. K. , Wen Haidan , DiChiara Anthony D. , Agnus Guillaume , Shpyrko Oleg G. , Fullerton Eric E. , Ravelosona Dafiné , Lecoeur Philippe , Kukreja Roopali
Published: May 2019

Ferroelectric materials exhibit coupled degrees of freedom and possess a switchable electric polarization coupled to strain, making them good piezoelectrics and enabling numerous devices including nonvolatile memories, actuators, and sensors. Moreover, novel photovoltaic effects are encountered through the interplay of electric polarization with the material optical properties. Consequently, light‐induced deformation in ferroelectrics, or photostriction, combining photovoltaic and converse piezoelectric effects, is under investigation in the quest for multifunctional materials. Using time‐resolved X‐ray diffraction, the first control of ultrafast photoinduced strain is demonstrated through in situ tuning of the polarization state in ferroelectric‐based devices. Both the magnitude and the sign of the photoinduced strain strongly depend on the transient photoinduced change of the internal electric field in the ferroelectric layer, and can be actively engineered to achieve two distinct remanent photostrictive responses. These results provide fundamental insight into light–matter interaction in ferroelectrics and exciting new avenues for materials functionality engineering.
Laser‐Triggered Large Magnetoresistance Change Observed in Corbino Disk of Cu/SiO2/Si
Authors: Dong Xinyuan , Zheng Diyuan , Yuan Meng , Zhou Peiqi , Niu Yiru , Dong Anhua , Wang Hui
Published: May 2019

The Corbino disk is used to study magnetoresistance as it eliminates Hall‐voltage interference and allows for direct probing of bulk properties. A laser‐triggered magnetoresistance effect in the Corbino disk of a Cu/SiO2/Si structure is reported. When a laser is applied, the magnetoresistance is greatly improved, by 360 times, under a 635 nm laser and a 2.1T magnetic field. In addition, the effect shows a close connection with the geometry of the nanoscale metal‐film structure. This effect is attributed to an increase in carrier concentration and bending of the motion path under the laser and magnetic field. This work suggests a new approach for the exploration of the magnetoelectric properties of nanoscale metal films and opens a new window on the use of light to adjust magnetoresistance devices.
Tunable Magnetic Response in 2D Materials via Reversible Intercalation of Paramagnetic Ions
Authors: Li Kerui , Chang Ting‐Hsiang , Xie Qidong , Cheng Youdong , Yang Haitao , Chen Jingsheng , Chen Po‐Yen
Published: May 2019

The unique properties of 2D materials spur fundamental studies and advanced technologies. As one of the important properties, magnetism is highly desired to be incorporated into various 2D materials for an active magnetic response, yet it remains challenging to develop a generalized and controllable method to magnetize a wide‐range of 2D materials reversibly. In this work, a reversible magnetization method is demonstrated for introducing the active magnetic response to various 2D material multilayers, ranging from graphene oxide (GO) to montmorillonite, titanium carbide (MXene), molybdenum disulfide (MoS2), and metal–organic framework, via the de‐/intercalation of holmium ions (Ho3+). The magnetic response can be tuned up to eight‐ to tenfold increases of the magnetic susceptibilities in all 2D materials by simply controlling the soaking time in the Ho ion solution. Moreover, the magnetic response can be quickly reversed by undergoing a rinsing process in dilute acids together with the recovery of intrinsic physicochemical properties of 2D materials. As a result, the improved magnetic response allows manipulation of the magnetized 2D materials, enabling the development of a magnet‐assisted transfer process for large‐area 2D material films as well as the fabrication of magnetically responsive 2D material actuators.
Ultrathin TiOx Interface‐Mediated ZnO‐Nanowire Memristive Devices Emulating Synaptic Behaviors
Authors: Xiao Ming , Yeow Travis , Nguyen Viet Huong , Muñoz‐Rojas David , Musselman Kevin P. , Duley Walter W. , Zhou Y. Norman
Published: May 2019

One‐dimensional semiconductor nanowires have been widely used as important building blocks in a number of devices. However, the performance of these devices is seriously hindered by the surface states/defects on the nanowires, which is a great obstacle to the realization of controllable and predictable characteristics. The introduction of an ultrathin metal oxide layer between Au electrodes and a ZnO nanowire is used to eliminate the surface effects of the nanowires, leading to improved volatile threshold switching performance. Study of the conduction mechanism demonstrates that the TiOx interfacial layer functions as a barrier between the electrodes and the nanowire, wherein the oxygen defects provide localized trap sites for electron hopping in a low electric field as well as assisting electron tunneling in a high electric field. Several key synaptic functions, including excitatory current response, facilitation and depression, and short‐term plasticity, are realized with this modified nanowire device, which is promising for neuromorphic computing applications. Interface engineering between electrodes and semiconductor nanowires can help in the realization of high‐performance memristive devices, allowing new approaches to the assembly of neuromorphic systems with nanometer‐sized features.
Fusing Nanowires into Thin Films: Fabrication of Graded‐Heterojunction Perovskite Solar Cells with Enhanced Performance
Authors: Zhang Yi , Yang Hanjun , Chen Min , Padture Nitin P. , Chen Ou , Zhou Yuanyuan
Published: May 2019

Perovskite solar cells (PSCs) have recently experienced a rapid rise in power conversion efficiency (PCE), but the prevailing PSCs with conventional mesoscopic or planar device architectures still contain nonideal perovskite/hole‐transporting‐layer (HTL) interfaces, limiting further enhancement in PCE and device stability. In this work, CsPbBr3 perovskite nanowires are employed for modifying the surface electronic states of bulk perovskite thin films, forming compositionally‐graded heterojunction at the perovskite/HTL interface of PSCs. The nanowire morphology is found to be key to achieving lateral homogeneity in the perovskite film surface states resulting in a near‐ideal graded heterojunction. The hidden role of such lateral homogeneity on the performance of graded‐heterojunction PSCs is revealed for the first time. The resulting PSCs show high PCE up to 21.4%, as well as high operational stability, which is superior to control PSCs fabricated without CsPbBr3‐nanocrystals modification and with CsPbBr3‐nanocubes modification. This study demonstrates the promise of controlled hybridization of perovskite nanowires and bulk thin films for more efficient and stable PSCs.
Gas hold‐up and bubble behavior in an upflow packed bed column in the limit of low flow rate
Authors: Taghavi Mahsa , Balakotaiah Vemuri
Published: May 2019

Significance

Gas–liquid up‐flow in a packed bed is studied experimentally in the limit of zero flow rate. Two patterns of bubble behavior are detected based on the magnitude of the Bond number (Bo). The gas hold‐up of the bed is found to be nonmonotonic with a maximum around Bo of unity. The bubble to particle diameter ratio is found to scale inversely with Bo.
Rational design of double salt ionic liquids as extraction solvents: Separation of thiophene/n‐octane as example
Authors: Song Zhen , Hu Xutao , Zhou Yageng , Zhou Teng , Qi Zhiwen , Sundmacher Kai
Published: May 2019

Although double salt ionic liquids (DSILs) offer significant advantages over classical two‐ion ionic liquids as separation solvents, relevant studies are still scarce and a systematic DSIL selection method is thus highly desirable. In this contribution, a rational method for designing DSILs as extraction solvents is proposed and exemplified by the thiophene/n‐octane separation. The effects of additional degrees of freedom for DSIL design (i.e., double cations and/or anions and the ion ratio) on the thermodynamic properties are first analyzed by COSMO‐RS. Then, a multilevel DSIL design method combining the prediction of infinite dilution thermodynamic properties, the estimation of physical properties, the evaluation of phase equilibrium behavior, and the experimental validation is proposed. By applying this method, [C2MIm][OAc]
x[NO3]1‐x (x = [0, 1]) and [C2MIm][OAc]
x[SCN]1‐x (x = [0.70, 1]) are identified as promising DSIL solvents for the thiophene/n‐octane separation. Correspondingly, the liquid–liquid equilibria of {DSILs + thiophene + n‐octane} with the designed DSILs are experimentally studied.
Nicht‐unschuldiger Methylen‐Linker in verbrückten Lewis‐Paar‐ Initiatoren
Authors: Weger Michael , Grötsch Raphael K. , Knaus Maximilian G. , Giuman Marco M. , Mayer David C. , Altmann Philipp J. , Mossou Estelle , Dittrich Birger , Pöthig Alexander , Rieger Bernhard
Published: May 2019

Die Deprotonierung tritt in der Regel als unerwünschte Nebenreaktion bei der Lewis‐Paar‐Polymerisation von Michael‐Akzeptoren auf, bei der die konjugierte Addition der Lewis‐Base an das säureaktivierte Monomer der gängige Initiationsmechanismus ist. Dies wurde auch für B‐P‐basierte verbrückte Lewis‐Paare (Bridged Lewis Pairs, BLPs) berichtet, die makrozyklische Additionsprodukte bilden. Wir konnten zeigen, dass bei Al‐P‐basierten BLPs die bisher unerwünschte Deprotonierung der wahrscheinliche Initiationsweg ist. In einer detaillierten Studie mit einer Reihe von Al‐P‐basierten BLPs unter Verwendung von Einkristalldiffraktometrie (Röntgen und Neutronen) und mechanistischen Untersuchungen (experimentell und rechnerisch) wurde eine aktive Rolle der Methylenbrücke aufgedeckt, die als Base für die α‐aziden Monomere agiert. Darüber hinaus bewiesen Polymerisationsstudien ein lebendes Verhalten in Kombination mit signifikant hohen Aktivitäten, engen Molmassenverteilungen und der Möglichkeit zur Copolymerisation.
Total Syntheses of Rhodomolleins XX and XXII: A Reductive Epoxide‐Opening/Beckwith–Dowd Approach
Authors: Yu Kuan , Yang Zhen‐Ning , Liu Chun‐Hui , Wu Shao‐Qi , Hong Xin , Zhao Xiao‐Li , Ding Hanfeng
Published: May 2019

A new TiIII‐mediated reductive epoxide‐opening/ Beckwith–Dowd rearrangement process efficiently assembles the bicyclo[3.2.1]octane framework of highly oxidized grayanane diterpenoids. By incorporation of a Cu(tbs)2‐catalyzed (tbs=N‐tert‐butylsalicylaldiminato) intramolecular cyclopropanation, a diastereoselective oxidative dearomatization‐induced Diels–Alder cycloaddition and a MeReO3‐catalyzed Rubottom oxidation, this approach has enabled the first total syntheses of rhodomolleins XX and XXII in 23 and 22 steps, respectively.
Methanol dissociation and oxidation on single Fe atom supported on graphitic carbon nitride
Authors: Lv Junlan , Feng Wei , Yang Siwei , Liu Huiling , Huang Xuri
Published: May 2019

Considering environmental protection and sustainable development, fuel cells have always been an ideal choice for clean energy. For the performance of fuel cells, the anode catalysts are a key consideration. In the work reported, we designed a new type of anode catalyst, in which graphitic carbon nitride was used as the substrate and transition metal iron as the supported atom. The calculation results were characterized by adsorption energy, reaction energy barrier, potential energy surface and charge analysis. Based on density functional theory, the gradual decomposition of methanol molecules on the catalyst is realized; the decomposition products are oxidized to reduce the formation of CO, and the efficiency of anode catalysis is improved, which provides a new idea for the design of anode materials for methanol fuel cells.
Evaluation of electron beam‐induced crosslinking of poly(ε‐caprolactone)—Effect of elevated temperatures
Authors: Huang Ying , Gohs Uwe , Müller Michael Thomas , Zschech Carsten , Wiessner Sven
Published: May 2019

The effect of elevated temperatures (40, 80, and 170 °C) on the electron beam (EB)‐induced crosslinking and degradation of poly(ε‐caprolactone) (PCL) in nitrogen atmosphere without adding crosslinking agents has been investigated. The increased mass average molecular mass of EB modified masticated PCL (mPCL) samples were measured by size exclusion chromatography. The sol–gel investigation showed that mPCL tended to dominating crosslinking at a temperature of 170 °C. At this temperature, the maximum gel content of 56% was observed for an EB treatment with a dose of 100 kGy. In addition, the ratio of chain scission density to density of crosslinked units amounted to 0.25. The dynamic rheological test demonstrated that EB treatment at 170 °C led to the most remarkable elasticity enhancement behavior with enhanced viscosity, modulus, and decreased loss factor (tan δ). The occurrence of branching structure was evidently detected by van Gurp–Palmen plot in combination with the Cole–Cole plot for dose values ≤50 kGy. Less δ and a broadened relaxation process can be observed due to the introduction of some branched structures into mPCL. The results of enhanced molar mass and gel content analysis were confirmed by the dynamic rheological measurements. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47866.
Formation mechanism of asymmetric porous polymer films by photoinduced phase separation in the presence of solvent
Authors: Yoshihara Hirokazu , Yamamura Masato
Published: May 2019

Photoinduced phase separation in the presence of a nonreactive volatile solvent provides a simple, light‐tunable, and cost‐effective route for fabrications of porous polymer films. Here, we show that the short‐time (<10 s) ultraviolet irradiation of a photoreactive solution film promotes particular asymmetries in the composition and porosity across the thickness. Confocal Raman spectroscopy revealed that the compositional asymmetry is maximum at a certain critical light intensity. We discuss the film formation mechanism based on the light‐driven diffusion of the solvent and monomer. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47867.
Preparation and characterization of paraffin microcapsules for energy‐saving applications
Authors: Mert Mehmet Selçuk , Mert Hatice Hande , Yilmaz Gumus Cansu
Published: May 2019

A series of microencapsulated phase‐change materials (PCMs) with styrene–divinyl benzene shells composed of an n‐octadecane (OD or C18)–n‐hexadecane (HD or C16) mixture as the core were synthesized by an emulsion polymerization method. The effects of the core/shell ratio (C/S) and surfactant concentration (Csurf) on the thermal properties and encapsulation ratios of the PCMs were investigated. The chemical structures and morphological properties of the microcapsules were characterized by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy analysis, respectively. The characteristic peaks of the paraffin mixtures and shell material located in the FTIR spectrum of the microencapsulated PCMs proved that the encapsulation of the PCM mixture was performed successfully. The thermal properties of the paraffin microcapsules were determined by differential scanning calorimetry (DSC) and thermogravimetric analysis. DSC analysis demonstrated that the microcapsules containing the maximum amount of paraffin mixture (C/S = 2:1) and the minimum Csurf (45 mmol/L) had the highest latent heat value of 88 kJ/kg and a latent heat of temperature of 21.06°C. Moreover, the maximum encapsulation ratio of the paraffin mixture was found to be 56.77%. With respect to the analysis results, the encapsulated binary mixture, which consisted of OD–HD with a poly(styrene‐co‐divinyl benzene) shell, is a promising material for thermal energy storage applications operating at low temperatures, such as in the thermal control of indoor temperatures and air‐conditioning applications in buildings for desirable thermal comfort and energy conservation. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47874.
Synthesis and improved mechanical properties of twin‐mesogenic epoxy thermosets using siloxane spacers with different lengths
Authors: Harada Miyuki , Hirotani Mio , Ochi Mitsukazu
Published: May 2019

A series of twin‐mesogenic epoxy resins with siloxane (di‐, tri‐, and tetra‐siloxane) chain spacers of different lengths were successfully synthesized. Results showed that the melting point of the twin‐mesogenic epoxy monomers decrease by more than 50 °C due to the change of siloxane spacer length. In particular, the tri‐ and tetra‐incorporated siloxane twin‐mesogenic epoxy monomers showed a liquid crystalline (LC) phase below 100 °C during the cooling process. Epoxy thermosets with isotropic and smectic (Sm) LC phases were then prepared using an aromatic amine and the dependence on curing temperature was investigated. Furthermore, the relationship between the ordered network chain structure and mechanical properties was investigated. Results were compared with isotropic and Sm LC phases. The tensile strain and fracture energy in the Sm type LC thermosets increased without a decrease in the tensile modulus, and this occurred in all systems irrespective of siloxane spacer length. The maximum value of the fracture energy (283 kJ m−2) reached by LC thermosets with increased spacer lengths was twice as large as that using the alkyl chain spacer (144 kJ m−2). © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47891.
Water‐swellable, tough, and stretchable inorganic–organic sulfoaluminate cement/polyacrylamide double‐network hydrogel composites
Authors: Chu Y. Y. , Song X. F. , Zhao H. X.
Published: May 2019

Effectively improving the mechanical properties of the hydrogel can greatly broaden its application range. The design concept of forming a double‐network structure by organic–inorganic hybridization can greatly enhance the mechanical properties of traditional hydrogels. Here, a series of organic–inorganic double‐network (OIDN) polyacrylamide/(sulfoaluminate cement) (PAM/SAC) composite gels by solution polymerization were synthesized at room temperature. The OIDN composite gels not only retain the characteristics of water swelling but also exhibit excellent tensile properties (stress and strain are 12 MPa and 2500%, respectively) and compressive strength (stress and strain are 65 MPa and 80%, respectively). In the preparation process, a brittle inorganic network of hydrated sulfoaluminate (hydra‐SAC) and a ductile network of polyacrylamide (PAM) were formed by the manner of interpenetrating. The phase composition and thermal stability of the OIDN composite gels were characterized and determined by FTIR, XRD, SEM, and TGA, respectively. The effect of SAC on swelling and mechanical performance of the OIDN composite gels was also investigated. The results show that the use of SAC hybrid hydrogels can effectively improve the mechanical strength, and the OIDN composite gels are expected to be a potential grouting and plugging functional material. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47905.
Sustainable rigid polyurethane foams based on recycled polyols from chemical recycling of waste polyurethane foams
Authors: Shin Se‐Ra , Kim Han‐Na , Liang Jing‐Yu , Lee Sang‐Hyub , Lee Dai‐Soo
Published: May 2019

The preparation and characteristics of rigid polyurethane foams (RPUFs) based on recycled polyol obtained by glycolysis of waste RPUF scraps from end‐of‐life refrigerators were investigated. To deactivate the amine adducts derived from isocyanates, the recycled product obtained after depolymerization was chemically modified via addition polymerization of propylene oxide. Two kinds of recycled polyols with different hydroxyl values and viscosity were blended with conventional virgin polyether polyol to prepare the RPUFs. The effects of the recycled polyols on the physical properties of RPUFs such as cell structures, compressive strength, thermal conductivity, and limiting oxygen index were discussed. It was found that the RPUFs from recycled polyols showed superior compressive strength, thermal insulation property, and self‐extinguishing property compared with conventional control foam. The results of this study reveal that the recycled polyols could be used as feedstock for RPUFs with superior performance. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47916.
Copper‐Catalyzed Alkylarylation of Unactivated Alkenes: Synthesis of 3‐Alkyl Indolines from N‐Allyl Anilines and Alkanes
Authors: Liang Deqiang , Huo Bojie , Dong Yongrui , Wang Yan , Dong Ying , Wang Baoling , Ma Yinhai
Published: May 2019

A rare example of C(sp3)−H functionalization of simple alkanes with unactivated alkenes is presented. In the presence of a copper salt and di‐tert‐butyl peroxide (DTBP), N‐allyl anilines underwent exo‐selective alkylation/cyclization cascade with unactivated alkenic bonds as radical acceptors and simple alkanes as radical precursors, providing a direct access to 3‐alkyl indolines. The present protocol features simple operation, broad substrate scope and great exo selectivity.
Long Afterglow Room‐Temperature Phosphorescence from Nanopebbles: A Urea Pyrolysis Product
Authors: Patir Khemnath , Gogoi Sonit Kumar
Published: May 2019

Materials having long afterglow are highly sought after for various applications such as light‐emitting diodes, security signs and bioimaging. Herein, we report a simple, low‐cost synthesis of a purely organic room‐temperature phosphorescent nanomaterial with a pebble‐like structure by heating urea, a biocompatible and easily available precursor, at 200 °C with a high phosphorescence lifetime of 1.0365 s and a visible afterglow for up to 10 s. This urea derived phosphorescent nanocomposite (UPNC) can be mixed with commercially available acrylic paint base and common gum, which can be readily used as a phosphorescent pigment.
Robust maneuver strategy of observer for bearings‐only tracking
Authors: He Renke , Chen Shuxin , Wu Hao , Liu Zhuowei , Chen Jianhua
Published: May 2019

For the bearings‐only tracking problem, an observer's maneuver can enhance the accuracy of estimation. However, it may be idealistic to expect the observer to move in the free space during reconnaissance missions, because threats in the motion space can restrict the motion space of the observer. In this study, considering the constraint of threats avoidance on the motion space of the observer, an optimal maneuver strategy was proposed. Firstly, the adaptive cubature Kalman Filter method was established to improve the robustness and accuracy of state estimation. Then the finite horizon Markov Decision VProcess approach was improved to generate the optimal maneuver policy, in which the quantization method was responsible for discretizing the process and providing the transition matrix for Markov Decision Process, and the novel reward function was proposed as the criterion for optimization. Finally, the framework of the method was established. The numerical results verified the feasibility and advantage of the proposed method by comparing them with state of the art research in the field.
Scale effects of topographic ruggedness on precipitation over Qinghai‐Tibet Plateau
Authors: Lu Ning
Published: May 2019

Due to the complex topography in mountainous areas, the pattern of precipitation is impacted by the topographic ruggedness (TR) that is characterized from Digital Elevation Model and thus scale‐dependent. Scale effects on the precipitation–TR relationship have not been well known in the Qinghai‐Tibet Plateau. Based on station measurements of precipitation in the domain, this study uses the quantile regression method to investigate the response of precipitation quantiles in summer and winter to the TR changes at different spatial scales. It is found that the scale variations impede the validity analysis of precipitation–TR relations. Neither too large (>100 km) or too small (<1 km) scales are suitable for exploring summer precipitation, and the scales are better less than 30 km for high winter precipitation. The analyses address that the precipitation–TR relations depend on appropriate spatial scales, which is important for statistical downscaling and model projection of precipitation in the Qinghai‐Tibet Plateau.