bluuebunny/crossref_metadata_2025 huggingface dataset:
Dezincification of brass water meters in a long-term study: effects of anions, alkalinity, and residual chlorine
Authors: Chao Shu-Ju , Tsai Ming-Han , Yu Rui-Pei , Hua Lap-Cuong , Hu Chi-Chang , Huang Chihpin
Published: July 2021

Brass water meters suffer the most severe dezincification under mixed water conditions of high anion concentrations and residual chlorine with low alkalinity after a 376 days long-term pipeline experiment.
K2S2O8-catalyzed highly regioselective amidoalkylation of diverse N-heteroaromatics in water under visible light irradiation
Authors: Zhou Jiadi , Ren Quanlei , Xu Ning , Wang Chaodong , Song Shengjie , Chen Zhi , Li Jianjun
Published: July 2021

A K2S2O8-catalyzed versatile C(sp2)–C(sp3) bond formation with N-heteroaromatics and γ-lactams/amides in H2O with high regioselectivity was developed.
Nanoparticles in analytical laser and plasma spectroscopy – a review of recent developments in methodology and applications
Authors: Galbács G. , Kéri A. , Kohut A. , Veres M. , Geretovszky Zs.
Published: July 2021

There is a mutually supportive relationship between materials science (nanoparticles) and analytical laser/plasma spectroscopy.
Atomic spectrometry update – a review of advances in X-ray fluorescence spectrometry and its special applications
Authors: Vanhoof Christine , Bacon Jeffrey R. , Fittschen Ursula E. A. , Vincze Laszlo
Published: July 2021

This review covers developments in and applications of XRF techniques such as EDXRF, WDXRF, TXRF, XRF microscopy using technologies such as synchrotron sources, X-ray optics, X-ray tubes and detectors, in laboratory, mobile and hand-held systems.
Engineering amino-mediated copper nanoclusters with dual emission and assembly-to-monodispersion switching by pH-triggered surface modulation
Authors: Han Bingyan , Yan Qifang , Xin Ze , Liu Qingdong , Li Dan , Wang Jiao , He Gaohong
Published: July 2021

We synthesized l-cysteine (Cys)-mediated copper nanoclusters (CuNCs) with assembly-to-monodispersion switching by pH-triggered surface modulation, where aggregated red emissive (R)-CuNCs@Cys at pH = 3 turns to monodispersed blue emissive (B)-CuNCs@Cys at pH = 10.
Unveiling the critical role of ammonium bromide in blue emissive perovskite films
Authors: Wang Xuechun , Cai Lei , Zou Yatao , Liang Dong , Wang Lu , Li Ya , Zang Jiaqing , Bai Guilin , Gao Xingyu , Song Tao , Sun Baoquan
Published: July 2021

The molecular structure of the ammonium halide plays a critical role in determining the quality of the blue perovskite film and light-emitting diodes.
Selective cleavage and reconstruction of C–N/C–C bonds in saturated cyclic amines: tunable synthesis of lactams and functionalized acyclic amines
Authors: He Yan , Yang Jintao , Zhang Xinying , Fan Xuesen
Published: July 2021

Selective cleavage of C–N/C–C bonds in saturated cyclic amines for the tunable synthesis of lactams and functionalized acyclic amines under the promotion of oxoammonium salt and TBHP in the presence of different additives have been developed.
Identification and in situ removal of an inhibitory intermediate to develop an efficient phytosterol bioconversion process using a cyclodextrin-resting cell system
Authors: Wang Da , Zhang Jian , Cao Dan-Dan , Wang Xuedong , Wei Dongzhi
Published: July 2021

We identified an inhibitory intermediate, 4-ene-3-keto steroids, that limits the bioconversion rate and provided a solution based on resin adsorption for improving 9α-OH-AD production efficiency in a commercial-scale process.
A class of novel luminescent layered double hydroxide nanotubes
Authors: Nanclares Dimy , Morais Alysson F. , Calaça Thainá , Silva Ivan G. N. , Mustafa Danilo
Published: July 2021

The incorporation of triply charged lanthanides in layered double hydroxides (LDHs) enables the curvature of the LDH sheets, unlocking the possibility of using a soft templating strategy to produce a class of luminescent, hierarchical LDH nanotubes.
Potentialities of bioinspired metal and metal oxide nanoparticles in biomedical sciences
Authors: Singh Kshitij RB , Nayak Vanya , Singh Jay , Singh Ajaya Kumar , Singh Ravindra Pratap
Published: July 2021

Bioinspired metallic nanoparticles (BMN) have revolutionized the biomedical domain and are still developing rapidly. Hence, this review on BMN elaborates the properties, biosynthesis, biomedical applications, and its role in combating the SARS-CoV-2.
Correction: Surface reaction kinetics of the methanol synthesis and the water gas shift reaction on Cu/ZnO/Al2O3
Authors: Lacerda de Oliveira Campos Bruno , Herrera Delgado Karla , Wild Stefan , Studt Felix , Pitter Stephan , Sauer Jörg
Published: July 2021

Correction for ‘Surface reaction kinetics of the methanol synthesis and the water gas shift reaction on Cu/ZnO/Al2O3’ by Bruno Lacerda de Oliveira Campos et al., React. Chem. Eng., 2021, 6, 868–887; DOI: 10.1039/D1RE00040C
Shear stress dependence of force networks in 3D dense suspensions
Authors: Edens Lance E. , Alvarado Enrique G. , Singh Abhinendra , Morris Jeffrey F. , Schenter Gregory K. , Chun Jaehun , Clark Aurora E.
Published: July 2021

The geometric organization and force networks of 3D dense suspensions that exhibit both shear thinning and thickening have been studied as a function of interparticle attractive interaction strength using lubrication flow discrete element modeling.
Layered electrode materials for non-aqueous multivalent metal batteries
Authors: Morag Ahiud , Yu Minghao
Published: July 2021

Multivalent metal batteries are promising large-scale energy storage technologies. This review summarizes the recent progress in the development of layered cathode materials for non-aqueous multivalent metal batteries.
Modulation of the optical properties of ZnS QD-embedded glass through aluminum and manganese doping
Authors: Li Kai , Ye Ying , Zhang Wenchao , Hu Yuzhou , Yang Ying , Zhou Yao , Liu Chao
Published: July 2021

Incorporation of Al3+ ions into ZnS QDs is found to induce VZn, which act as a dispersant to reduce the concentration quenching of the Mn-related emission and achieve energy transfer from the ZnS QDs to Mn2+ ions, long lifetime, and high PL QYs.
Unexpectedly flexible graphene nanoribbons with a polyacene ladder skeleton
Authors: Unruh Marvin T. , Scherf Ullrich , Bahmann Hilke , Rodrigues Ana Clara B. , Cunha Carla , Seixas de Melo J. Sérgio , Schedlbauer Jakob , Lupton John M.
Published: July 2021

A new aromatic ladder polymer with a polyacene skeleton shows an unexpectedly high flexibility of its double-stranded backbone.
Lightweight and robust cobalt ferrite/carbon nanotubes/waterborne polyurethane hybrid aerogels for efficient microwave absorption and thermal insulation
Authors: Luo Jiawei , Wang Yu , Qu Zhongji , Wang Wei , Yu Dan
Published: July 2021

Lightweight and efficient microwave absorption materials with excellent heat-insulating ability and mechanical property are highly attractive in real applications, but the effective integration of these functions into one material by a simple approach remains an enormous challenge.
A novel dynamic dual‐path routing for end‐to‐end communication security in wide area networks
Authors: Zhang Rongbo , Li Xin , Chen Shanzhi
Published: July 2021

Dynamic multipath routing gives users flexibility over the transmitting path to deliver messages for security. Several protocols have already presented, such as multipath TCP, random routing mutation. However, they often limited to scalability, which mainly reflects on two aspects of network resource consumption and compossibility with other main transfer protocols. In this paper, to enhance the security of data delivery in wide area networks, a novel multipath routing scheme for end‐to‐end communication is proposed. The basic idea is concurrently using two paths (a fixed path and a changing path) to deliver the data of a pair, the fixed routing path undertakes the main delivery tasks, and the continually changing routing path only transfers a little data of the flow during the whole communication period. For systematically achieving security, Information Dispersal Algorithm disperses the flow data over the two paths for resisting anyone routing path compromised. Further, the method can maintain more routing path change since the burst network resource requirement decreases significantly at the routing mutation moment. Meanwhile, it brings a small amount of bandwidth disturbance over the traffic statuses of the network, thus alleviating instead of worsening the compossibility with other protocols.
Euclidean space data alignment approach for multi‐channel LSTM network in EEG based fatigue driving detection
Authors: Tang Jiahao , Li Xueping , Yang Yuan , Zhang Wan
Published: July 2021

Fatigue driving is the main reason of traffic accidents. The electroencephalograph (EEG) signal can accurately reflect the changes of human physiological state, so EEG is considered as a reliable method to detect fatigue driving. In this letter, the Euclidean space data alignment approach is adopted to reduce individual differences. Then, to consider the spatial correlation between multiple channels EEG signals and further improve the accuracy, an efficient long short‐term memory (LSTM) network structure is designed to detect the fatigue state of drivers. The experimental result shows that the method improves the generalisation capability and achieves the performance with an average accuracy of 95.70% for three categories. Evaluation of the algorithm performance in comparison with other traditional methods indicates that the method has higher accuracy and lower standard deviation. Generally speaking, the proposed method is promising for the application of fatigue driving monitoring.
Synthesis of chitosan functionalized magnetic carbon nanotubes for dispersive solid‐phase extraction of bromocresol green
Authors: Abniki Milad , Moghimi Ali
Published: July 2021

Abstract

This study presents a new and rapid method for preconcentration, measurement, and removal of trace amounts of coloured wastewater using chitosan functionalized magnetic carbon nanotubes in aqueous samples. This method involves a two‐phase system in which the donor phase contains an aqueous phase with bromocresol green, and the acceptor phase contains functionalized magnetic carbon nanotubes with chitosan. Experiments were carried out in two stages of extraction of bromocresol green from aqueous solution and desorption of bromocresol green using ethanol solvent. The samples were analysed by UV–Vis spectrophotometer. Extraction parameters were investigated such as the effect of organic solvent, pH of the donor and acceptor phases, extraction time, interference species, and volume of elution solvent. The isotherm of bromocresol green adsorption was fine described by the Langmuir model, and the adsorption capacity in the maximum was 28.49 mg g−1. The preconcentration factor and limit of detection for bromocresol green were 14.3 and 7.5 μg L−1, respectively. A linear range is observed between 0.1 and 20 mg L−1. Finally, the chitosan functionalized magnetic carbon nanotubes (Fe3O4@MWCNT‐CN) exhibited a high potential for removing the bromocresol green from aqueous samples.
Two‐dimensional adaptive beamforming for large planar array antennas based on weight matrix reconstruction
Authors: Gao Wei , Li Xiaoming , Liu Zheng , Meng Ziqiang , Ran Lei
Published: July 2021

Adaptive beamformers at the element level usually require a great number of training samples and the computational cost for calculating the weight vector for large phased array antennas is very high, which make it difficult for real‐time applications. To address this problem, a two‐dimensional (2‐D) adaptive beamformer applicable to large planar array antennas that have low computational complexity and low training sample requirement is proposed. In the proposed method, the weight matrix is first reconstructed as a matrix that has the same or close columns and rows by utilising the special Kronecker property of the array steering matrix. Then, the weight vector is determined by adopting a bi‐quadratic cost function and a bi‐iterative algorithm. Experimental results show that the proposed method can achieve fairly good performance even when the training samples are small.
Preparation of Functionalized Diorganomagnesium Reagents in Toluene via Bromine or Iodine/Magnesium-Exchange Reactions
Authors: Desaintjean Alexandre , Danton Fanny , Knochel Paul
Published: July 2021

A wide range of polyfunctionalized di(hetero)aryl- and dialkenyl-magnesium reagents are prepared in toluene within 10 to 120 minutes between –78 °C and 25 °C via an I/Mg- or Br/Mg-exchange reaction using reagents of the general formula R2Mg (R = sBu, Mes). Highly sensitive functional groups, such as triazene or nitro, are tolerated in these exchange reactions, enabling the synthesis of various functionalized (hetero)arene and alkene derivatives after quenching with several electrophiles including allyl bromides, acyl chlorides, aldehydes, ketones, and aryl iodides.
Lhermitte–Duclos Disease Mimicking Cerebellopontine Angle Tumor: A Case Report
Authors: Abbasoglu Bilal , Zaimoglu Murat , Eroglu Umit , Ersoz Cevriye Cansiz , Attar Ayhan
Published: July 2021

Lhermitte-Duclos disease (LDD) is dysplastic gangliocytoma of the cerebellum, which is rare, tends to grow slowly, usually has good prognosis, and wherein the cerebellar cortex becomes thick and the central white matter is not observed. On MRI of the brain, it has hyperintense and hypointense presentations on T2- and T1-weighted scans, respectively. It has nonhomogenous contrasting pattern on T1-contrast scans. LDD can be seen unilaterally or bilaterally in the cerebellum. When the disease is located at the cerebellopontine angle, it can be mistaken for the tumors located in this region. Recurrence can occur postoperatively, which is rare. The present case is a rare one because the tumor was located at the cerebellopontine angle and radiologically mimicked cerebellopontine angle tumors.
Simple Removal of Ventriculoatrial Shunt and Simultaneous Ventriculoperitoneal Shunt Revision: Short Communication
Authors: Oike Ryo , Inoue Yasuaki , Matsuzawa Kazuhito
Published: July 2021

Background  Ventriculoatrial shunt (VAS) is a common alternative treatment option for hydrocephalus in patients with ventriculoperitoneal shunt (VPS) failure. Most previous reports on VAS discuss the atrial-related complications and none focus on simple removal (i.e., without specialized equipment). We report a case of simple VAS removal and simultaneous VPS revision, with no obvious shunt-related cardiac complications.

Case presentation  The patient was an 87-year-old female who had received a VAS for idiopathic normal pressure hydrocephalus 6 years prior. She developed a right thalamic hemorrhage with intraventricular hemorrhage and was admitted to our hospital. She had a recurrence of the hydrocephalus and was diagnosed with shunt malfunction, due to simple obstruction without obvious shunt-related cardiac complications. The VAS was simply and safely removed, and a VPS was simultaneously placed, as per the usual procedure in our institution. She remains well with no evidence of complications on postoperative day 10.

Discussion  Since VAS is mostly used in pediatric cases that are difficult to treat with VPS, the duration of time elapsed allows VAS catheters to form strong adhesions with the surrounding cardiac tissue. Therefore, the simple removal of VAS is usually not straightforward.

Conclusion  If the follow-up period is short and there are no specific cardiac complications at the time of replacement, VAS can be safely removed and VPS can be spontaneously placed, without any specialized surgical techniques or equipment.
Tendon: Principles of Healing and Repair
Authors: Chartier Christian , ElHawary Hassan , Baradaran Aslan , Vorstenbosch Joshua , Xu Liqin , Efanov Johnny Ionut
Published: July 2021

Tendon stores, releases, and dissipates energy to efficiently transmit contractile forces from muscle to bone. Tendon injury is exceedingly common, with the spectrum ranging from chronic tendinopathy to acute tendon rupture. Tendon generally develops according to three main steps: collagen fibrillogenesis, linear growth, and lateral growth. In the setting of injury, it also repairs and regenerates in three overlapping steps (inflammation, proliferation, and remodeling) with tendon-specific durations. Acute injury to the flexor and extensor tendons of the hand are of particular clinical importance to plastic surgeons, with tendon-specific treatment guided by the general principle of minimum protective immobilization followed by hand therapy to overcome potential adhesions. Thorough knowledge of the underlying biomechanical principles of tendon healing is required to provide optimal care to patients presenting with tendon injury.
Wound Healing: A Comprehensive Review
Authors: Almadani Yasser H. , Vorstenbosch Joshua , Davison Peter G. , Murphy Amanda M.
Published: July 2021

Wound healing is an intricate, tightly regulated process that is critical to maintaining the barrier function of skin along with preserving all other skin functions. This process can be influenced by a variety of modifiable and nonmodifiable factors. As wound healing takes place in all parts of the human body, this review focuses on cutaneous wound healing and highlights the classical wound healing phases. Alterations in any of these phases can promote chronic wound development and may impede wound healing.
A Rare Case of Dissemination of Primary Spinal Glioblastoma
Authors: Sirinoglu Deniz , Sarigul Buse , Baskurt Ozan , Aydin Mehmet Volkan
Published: July 2021

Background Primary spinal glioblastoma is a rare lesion which constitutes only 1.5% of all spinal tumors. Diagnosis is challenging due to absence of any radiological hallmark of the disease. Even though surgery combined with chemoradiotherapy is the optimal management for these tumors, prognosis is still poor. Dissemination of glioblastoma is reported several times in the literature, which is correlated with worse prognosis and outcome. This case report that we are presenting is the first case where dissemination of primary spinal glioblastoma dissemination is limited only to spinal cord, without intracranial invasion, and regression was achieved with chemoradiotherapy.

Case Report In this article, a patient with primary spinal glioblastoma who presented with paraparesia is presented. Patient underwent surgery for resection of the tumor and received adjuvant radiotherapy. However, 9 months postoperatively, dissemination was detected in epidural and subdural spaces of spinal canal, with concomitant compression of spinal cord. There was no radiographically detected lesion in cranial MRI. He underwent second session of radiotherapy, combined with chemotherapy and steroid. Five months later, regression of metastatic disseminated lesions was observed.

Conclusion Primary spinal glioblastoma is a rare pathology and known to have a poor prognosis, notably with dissemination of the disease. Even though further biomolecular studies are necessary to explain the pathophysiology better, chemotherapy and radiotherapy may be effective in regression of disseminated lesions.
Klinik Unternehmen: Auf-/Absteiger des Monats
Authors: Schmidt Hartmut
Published: July 2021

Börsenexperte Hartmut Schmidt analysiert für kma die Jahresabschlüsse ausgewählter Kliniken
Delir bei Covid-19: Risiken erkennen und gezielt behandeln
Authors: Hofbauer Lorenz C , Brandt Moritz D , Haußmann Robert , Donix Markus
Published: July 2021

Bei der stationären Versorgung betagter Covid-19-Patientinnen und -Patienten muss sich das Klinikpersonal des Risikos eines Post-Covid-Delirs bewusst sein. Interdisziplinäre Ansätze sind der Schlüssel zu guten Behandlungsergebnissen, einer Verbesserung der kognitiven Prognose nach Delir sowie einer Begrenzung von Hospitalisierungszeiten. Neben pharmakologischen und nicht-pharmakologischen Therapieaspekten spielen hier strukturelle Rahmenbedingungen und die altersmedizinische Expertise am Standort eine entscheidende Rolle.
Ausländische Pflegekräfte: Nur bessere Integration bindet dauerhaft
Authors: Thömen-Suhr Doris
Published: July 2021

Mit der Anwerbung von ausländischen Pflegekräften versuchen Kliniken, den Fachkräftemangel in der Pflege abzumildern. Doch deren Einsatz auf Station verläuft nicht immer spannungsfrei. Wer die Neuankömmlinge dauerhaft halten will, muss diese nachhaltig in etablierte Pflegeteams integrieren.
Mixed-mode oscillations from a constrained extended Bonhoeffer–van der Pol oscillator with a diode
Authors: Inaba Naohiko , Kousaka Takuji , Tsubone Tadashi , Okazaki Hideaki , Ito Hidetaka
Published: July 2021

An extended Bonhoeffer–van der Pol (BVP) oscillator is a circuit that is naturally extended to a three-variable system from a two-variable BVP oscillator. A BVP oscillator is known to exhibit a canard explosion, and the extended BVP oscillator generates mixed-mode oscillations (MMOs). In this work, we considered a case study where the nonlinear conductor in the extended BVP oscillator includes an idealized diode. The idealized case corresponds to a degenerate case where one of the parameters tends to infinity, and circuit dynamics are represented using a constrained equation, and at the expense of the model’s naturalness, i.e., in a case in which the solutions of the dynamics are defined only forward in time, the Poincaré return maps are constructed as one-dimensional (1D). Using these 1D return maps, we explain various phenomena, such as simple MMOs and MMO-incrementing bifurcations. In this oscillator, there exists a small amplitude oscillation, which emerges as a consequence of supercritical Hopf bifurcation, and there exists large relaxation oscillation which appears via canard explosion by changing the bifurcation parameter. Between these small and large amplitude oscillations, the MMO bifurcations exhibit asymmetric Farey trees. Furthermore, these theoretical results were verified using laboratory measurements and experiments.
Interface and optical properties of Zn1−xMgxO films with Mg content of more than 70% grown on the (12̄10)-ZnO substrates
Authors: Liang Xin , Zhou Hua , Wang Hui-Qiong , Zhang Lihua , Kisslinger Kim , Kang Junyong
Published: July 2021

Fabricating Zn1−xMgxO films with a high Mg content is key to their applications in deep-ultraviolet optoelectronic devices. In this work, we report the preparation of Zn1−xMgxO films on (12̄10)-ZnO substrates by molecular beam epitaxy. The Zn1−xMgxO/(12̄10)-ZnO structure is revealed by x-ray diffraction and high-resolution transmission electron microscopy. Remarkably, no cubic MgO is observed for films with 74.6% Mg content; the film shows mainly the wurtzite structure with some intermediate phases at the interface. Photoluminescence spectra show that the film exhibits good optoelectronic properties with a bandgap of 4.6 eV. This work provides a new avenue for the fabrication of deep-ultraviolet Zn1−xMgxO films.
Femtosecond laser-induced nitrogen fluorescence emission at different air pressures
Authors: Lin Shuang , Zhang Yun , Zhang He , Zhang Yunfeng , Chang Mingying , Wang Xiaoting , Chen Anmin , Jiang Yuanfei , Li Suyu , Jin Mingxing
Published: July 2021

In this paper, we experimentally investigate femtosecond laser-induced nitrogen fluorescence emission at different air pressures (0.1 Pa–100 kPa). The variation of nitrogen molecule (N2) and molecular nitrogen ion (N2+) characteristic fluorescence spectral lines' intensity as a function of air pressure is observed. When the air pressure is between 10 Pa and 100 kPa, the intensity of fluorescence signals from N2+ and N2 shows opposite variation as a function of air pressure. We deduce that dissociative recombination is the main pathway for the production of the C3∏u state of N2. This research helps elucidate the physical emission mechanism of femtosecond laser-induced nitrogen fluorescence emission.
Digitally controlled laser frequency stabilization for a ring laser using saturated absorption
Authors: Udommai Parinya , Harvey Matthew , Murray Andrew James
Published: July 2021

A digital system for controlling the frequency of a continuous wave (CW) ring laser is described. The system utilizes Doppler-free absorption to steer the laser onto a resonance peak within a vapor cell and can hold the laser at this frequency for long periods of time using active feedback. The vapor cell is immersed in a sinusoidally varying magnetic field that produces a feedback signal by exploiting the Zeeman effect so that the laser frequency does not need to be dithered to achieve lock. A bias field can also be applied to adjust the frequency over several MHz while maintaining lock. This is advantageous for cold atom studies that require the laser to be red-detuned from resonance. Signals from the absorption cell and magnetic field are digitized and fed to a dedicated microcontroller that calculates and produces the feedback signal. The digital control system is described, and measurements are presented where the locked frequency is compared to data obtained from a commercial wavemeter. The locked frequency standard deviations ranged from 250 to 450 kHz within a 1 h period. The Allan deviations of the locked frequency had the best stability at a value of 6 × 10−11 in a 10 s averaging period. The locking system described here has application in experiments that require very stable laser frequency control and can also be used for regular recalibration of wavemeter parameters. The design can easily be adapted to control different CW laser systems and hence can be used for a range of atomic targets.
Ion mobility independent large signal switching of perovskite devices
Authors: Saketh Chandra Tirupati , Singareddy Abhimanyu , Hossain Kashimul , Sivadas Dhyana , Bhatia Swasti , Singh Shivam , Kabra Dinesh , Nair Pradeep R.
Published: July 2021

The presence of mobile ions in perovskites is well known to influence the device electrostatics leading to a wide variety of anomalous characteristics related to hysteresis, efficiency degradation, low frequency capacitance, large signal switching, etc. Accordingly, the ion mobility is understood to a have a critical influence on the associated time constants/delays. Quite contrary to this broadly accepted thought, here we suggest that the time delays associated with large signal switching could show a universal behavior dictated by electronic dipoles, rather than ionic dipoles. Due to the resultant sudden and dramatic collapse of a contact layer depletion region, large signal switching delays are independent of ion mobilities. Furthermore, our detailed numerical simulations, supported by experimental results, indicate that terminal currents show a near steady state behavior well ahead of the relaxation of ionic distributions. These results have interesting implications toward the understanding and optimization of perovskite based electronic devices, including solar cells, LEDs, resistive memories, and ferroelectric memories.
Effect of surface properties and polymer chain length on polymer adsorption in solution
Authors: Lin Emily Y. , Frischknecht Amalie L. , Winey Karen I. , Riggleman Robert A.
Published: July 2021

In polymer nanoparticle composites (PNCs) with attractive interactions between nanoparticles (NPs) and polymers, a bound layer of the polymer forms on the NP surface, with significant effects on the macroscopic properties of the PNCs. The adsorption and wetting behaviors of polymer solutions in the presence of a solid surface are critical to the fabrication process of PNCs. In this study, we use both classical density functional theory (cDFT) and molecular dynamics (MD) simulations to study dilute and semi-dilute solutions of short polymer chains near a solid surface. Using cDFT, we calculate the equilibrium properties of polymer solutions near a flat surface while varying the solvent quality, surface–fluid interactions, and the polymer chain lengths to investigate their effects on the polymer adsorption and wetting transitions. Using MD simulations, we simulate polymer solutions near solid surfaces with three different curvatures (a flat surface and NPs with two radii) to study the static conformation of the polymer bound layer near the surface and the dynamic chain adsorption process. We find that the bulk polymer concentration at which the wetting transition in the poor solvent system occurs is not affected by the difference in surface–fluid interactions; however, a threshold value of surface–fluid interaction is needed to observe the wetting transition. We also find that with good solvent, increasing the chain length or the difference in the surface–polymer interaction relative to the surface–solvent interaction increases the surface coverage of polymer segments and independent chains for all surface curvatures. Finally, we demonstrate that the polymer segmental adsorption times are heavily influenced only by the surface–fluid interactions, although polymers desorb more quickly from highly curved surfaces.
Data-assisted polymer retrosynthesis planning
Authors: Chen Lihua , Kern Joseph , Lightstone Jordan P. , Ramprasad Rampi
Published: July 2021

Polymer informatics is being utilized to accelerate polymer discovery. However, the practical realization of the designed polymer is still slow due to synthesis challenges, e.g., difficulties with the identification of potential polymerization mechanisms and optimal reactants/solvents/processing conditions. In the past, synthesis pathways adopted for a target polymer have been heavily dependent on chemical intuition and past experience. To expedite this process, we have developed a data-driven approach to assist in polymer retrosynthesis planning. In this work, a dataset of polymerization reactions was manually accumulated from various resources to extract hundreds of synthetic templates and used as the training set. Further, a similarity metric was adopted to select synthetic templates and similar existing reactants for the new target polymer. Finally, prediction accuracy was measured by comparison with ground truth and/or bench chemists' estimation. The proposed data-driven polymer synthesis recommendation model has been deployed at https://www.polymergenome.org.
Flow transition in periodically fully developed wavy channels
Authors: Harikrishnan S. , Kumar Prashant , Tiwari Shaligram
Published: July 2021

In the present study, numerical investigations have been performed to study the flow transition mechanism in wavy channels using finite volume-based open source field operation and manipulation. Two different wavy channel configurations are chosen, which represent two different flow destabilization mechanisms, viz., Kelvin–Helmholtz and centrifugal instabilities. Sinusoidal walls with out-of-phase and in-phase channel configurations have been considered in the present study. Steady to chaotic flow transition in two different channel configurations are investigated by varying Reynolds number. A detailed flow regime map is presented for the two different wavy channel configurations. Unsteady flow features have been illustrated with the help of instantaneous streamlines, velocity contours, vorticity contours, and iso-Q surfaces. For the out-of-phase configuration, the flow changes from two-dimensional steady to two-dimensional unsteady in the Re range of 175–185, and then three-dimensional unsteady flow is observed for the Re varying from 250 to 260. On the contrary, for the in-phase configuration, the transition happens directly from steady two-dimensional flow (Re < 101) to unsteady three-dimensional (Re > 102) in a very narrow range of Re. Transitions in the two different wavy channels have been examined in detail using Hilbert–Huang transformation, phase-space reconstruction, Poincaré section, recurrence plot, and dynamic mode decomposition. Frequency, growth rate, and vortex structures of the dominant modes are illustrated corresponding to each value of Re for the considered channel configurations.
Impacts of mutations on dynamic allostery of adenylate kinase
Authors: Song Haoyu , Wutthinitikornkit Yanee , Zhou Xiaozhou , Li Jingyuan
Published: July 2021

Escherichia coli adenylate kinase (AK) is composed of CORE domain and two branch domains: LID and AMP-binding domain (AMPbd). AK exhibits considerable allostery in a reversible phosphoryl transfer reaction, which is largely attributed to the relative motion of LID and AMPbd with respect to CORE. Such an allosteric conformational change is also evident in the absence of ligands. Recent studies showed that the mutations in branch domains can adjust dynamic allostery and alter the substrate affinity and enzyme activity. In this work, we use all-atom molecular dynamics simulation to study the impacts of mutations in branch domains on AK’s dynamic allostery by comparing two double mutants, i.e., LID mutant (Val135Gly, Val142Gly) and AMPbd mutant (Ala37Gly, Ala55Gly), with wild-type. Two mutants undergo considerable conformational fluctuation and exhibit deviation from the initially extended apo state to more compact structures. The LID domain in the LID mutant adjusts its relative position and firmly adheres to CORE. More strikingly, AMPbd mutations affect the relative positions of both the AMPbd domain and remote LID domain. Both domains undergo considerable movement, especially the inherent hinge swing motion of the flexible LID domain. In both mutants, the mutations can enhance the inter-domain interaction. The results about the conformation change of AK in both mutants are in line with the experiment of AK’s affinity and activity. As revealed by our findings, the flexibility of branch domains and their inherent motions, especially LID domain, is highly relevant to dynamic allostery in the AK system.
Adaptively reverse design of terahertz metamaterial for electromagnetically induced transparency with generative adversarial network
Authors: Zhang Zhen , Han Dai , Zhang Liuyang , Wang Xianqiao , Chen Xuefeng
Published: July 2021

Metamaterials for electromagnetically induced transparency (EIT) have promoted prosperous development of terahertz (THz) devices due to their counterintuitive manipulation rules on the electromagnetic responses. However, traditional design rules of EIT metamaterial require prior knowledge of unnatural parameters of geometrical structures. Here, by taking full advantages of unsupervised generative adversarial networks (GANs), we propose an adaptively reverse design strategy to achieve intelligent design of metamaterial structures with the EIT phenomenon. The game theory ingrained in the GAN model facilitates the effective and error-resistant design process of metamaterial structures with preset electromagnetic responses and vice versa. The close match between the preset electromagnetic response and that from the generated structure validates the feasibility of the GAN model. Thanks to high efficiency and complete independence from prior knowledge, our method could provide a novel design technique for metamaterials with specific functions and shed light on their powerful capabilities on boosting the development of THz functional devices.
A von Hamos spectrometer based on highly annealed pyrolytic graphite crystal in tender x-ray domain
Authors: Ismail Iyas , Journel Loïc , Vacheresse Régis , Travnikova Oksana , Marin Thierry , Céolin Denis , Guillemin Renaud , Marchenko Tatiana , Zmerli Moustafa , Koulentianos Dimitris , Püttner Ralph , Palaudoux Jérôme , Penent Francis , Simon Marc
Published: July 2021

We have built an x-ray spectrometer in a von Hamos configuration based on a highly annealed pyrolytic graphite crystal. The spectrometer is designed to measure x-ray emission in the range of 2–5 keV. A spectral resolution E/ΔE of 4000 was achieved by recording the elastic peak of photons issued from the GALAXIES beamline at the SOLEIL synchrotron radiation facility.
Optical magnetic response without metamaterials
Authors: Li Jinxiang , Papasimakis Nikitas , MacDonald Kevin F. , Zheludev Nikolay I.
Published: July 2021

One of the main achievements of metamaterials research has been the development of structured matter exhibiting optical magnetism: first, in an array of microwave split-ring resonators and, soon after, in plasmonic and dielectric metamaterials at THz to visible frequencies. We show here that metamaterial structuring is not necessary to achieve optical magnetic response. Indeed, such a response is an essential characteristic of homogeneous dielectric thin films—Fabry–Pérot resonances, for example, depend on interference among electromagnetic multipoles including the magnetic dipole.
Large magnetic entropy change in Nd2In near the boiling temperature of natural gas
Authors: Liu Wei , Scheibel Franziska , Gottschall Tino , Bykov Eduard , Dirba Imants , Skokov Konstantin , Gutfleisch Oliver
Published: July 2021

Natural gas is useful for the transition from traditional fossil fuels to renewable energies. The consumption of liquid natural gas has been rising, and the demand is predicted to double by 2040. In this context, magnetocaloric gas liquefaction, as an emerging and energy-saving technology, could be an alternative to the traditional gas-compression refrigeration. In this work, we report a large magnetic entropy change of 7.42 J/kg K under a magnetic field change of 2 T in Nd2In at 109 K, which is near the boiling temperature of natural gas of 112 K. The maximum adiabatic temperature change reaches 1.13 K under a magnetic field change of 1.95 T and is fully reversible. The magnetic phase transition is confirmed to be of the first-order type with the negligible thermal hysteresis. Further investigations on the thermal expansion and the magnetostriction reveal that the magnetic transition undergoes two stages with a negligible volume change. The longitudinal strain increases with magnetic fields and then decreases. These interesting properties are useful for the practical design of a magnetocaloric natural gas liquefaction system and for the fundamental understanding of the phase transitions in other RE2In intermetallics.
A temperature-dependent critical Casimir patchy particle model benchmarked onto experiment
Authors: Jonas H. J. , Stuij S. G. , Schall P. , Bolhuis P. G.
Published: July 2021

Synthetic colloidal patchy particles immersed in a binary liquid mixture can self-assemble via critical Casimir interactions into various superstructures, such as chains and networks. Up to now, there are no quantitatively accurate potential models that can simulate and predict this experimentally observed behavior precisely. Here, we develop a protocol to establish such a model based on a combination of theoretical Casimir potentials and angular switching functions. Using Monte Carlo simulations, we optimize several material-specific parameters in the model to match the experimental chain length distribution and persistence length. Our approach gives a systematic way to obtain accurate potentials for critical Casimir induced patchy particle interactions and can be used in large-scale simulations.
Experimental and numerical study of a split cathode fed relativistic magnetron
Authors: Leopold J. G. , Tov M. Siman , Pavlov S. , Goloborodko V. , Krasik Ya. E. , Kuskov A. , Andreev D. , Schamiloglu E.
Published: July 2021

The relativistic magnetron is one of the most efficient high power microwave (HPM) sources but pulse shortening, the result of explosive cathode plasma's radial expansion toward the anode, makes it impractical because the HPM pulse terminates much earlier than the applied voltage. We present experimental results of the operation of a relativistic magnetron fed by a split cathode. A split cathode [Leopold et al., Phys. Plasmas 27, 103102 (2020)] consists of a cathode placed upstream and outside the anode, connected by an axial rod to a reflector (a transverse conducting circular plate) placed downstream from the anode. The electron charge, emitted by an annular explosive cathode emitter, accumulates in the space between the cathode and the reflector and at the same time, screens the rod from explosive plasma formation. This accumulated space charge serves as the electron source for the magnetron. The explosive plasma developing on the emitter remains outside the magnetron and does not propagate into the anode while it operates. We compare the performance of the magnetron operating with a standard explosive emitting solid carbon cathode to that with a split cathode. The experiments demonstrate that whereas for the solid cathode, the microwave pulse developing in the magnetron suffers from pulse shortening, with a split cathode, the pulse survives as long as the amplitude of the applied voltage is sufficient for the magnetron's operation. We support the experiment by particle-in-cell simulations.
Electromagnetic field emitted by core–shell semiconductor nanowires driven by an alternating current
Authors: Torres Miguel Urbaneja , Klausen Kristjan Ottar , Sitek Anna , Erlingsson Sigurdur I. , Gudmundsson Vidar , Manolescu Andrei
Published: July 2021

We consider tubular nanowires with a polygonal cross section. In this geometry, the lowest energy states are separated into two sets, one the corner and the other side-localized states. The presence of an external magnetic field transverse to the nanowire imposes an additional localization mechanism: the electrons being pushed sideways relatively to the direction of the field. This effect has important implications on the current density as it creates current loops induced by the Lorentz force. We calculate numerically the electromagnetic field radiated by hexagonal, square, and triangular nanowires. We demonstrate that because of the aforementioned localization properties, the radiated field can have a complex distribution determined by the internal geometry of the nanowire. We suggest that measuring the field in the neighborhood of the nanowire could be the basic idea of the tomography of the electron distribution inside it if a smaller receiver antenna could be placed in that zone.
Effect of softness on glass melting and re-entrant solidification in mixtures of soft and hard colloids
Authors: Parisi Daniele , Camargo Manuel , Makri Kalliopi , Gauthier Mario , Likos Christos N. , Vlassopoulos Dimitris
Published: July 2021

We present a systematic investigation of the structure and dynamic properties of model soft–hard colloidal mixtures. Results of a coarse-grained theoretical model are contrasted with rheological data, where the soft and hard colloids are mimicked by large star polymers with high functionality as the soft component and smaller stars with ultrahigh functionality as the hard one. Previous work by us revealed the recovery of the ergodicity of glassy soft star solutions and subsequent arrested phase separation and re-entrant solid transition upon progressive addition of small hard depletants. Here, we use different components to show that a small variation in softness has a significant impact on the state diagram of such mixtures. In particular, we establish that rendering the soft component more penetrable and modifying the size ratio bring about a remarkable shift in both the phase separation region and the glass-melting line so that the region of restored ergodicity can be notably enhanced and extended to much higher star polymer concentrations than for pure systems. We further rationalize our findings by analyzing the features of the depletion interaction induced by the smaller component that result from the interplay between the size ratio and the softness of the large component. These results demonstrate the great sensitivity of the phase behavior of entropic mixtures to small changes in the molecular architecture of the soft stars and point to the importance of accounting for details of the internal microstructure of soft colloidal particles for tailoring the flow properties of soft composites.
Synchronization scenarios in three-layer networks with a hub
Authors: Sawicki Jakub , Koulen Julia M. , Schöll Eckehard
Published: July 2021

We study various relay synchronization scenarios in a three-layer network, where the middle (relay) layer is a single node, i.e., a hub. The two remote layers consist of non-locally coupled rings of FitzHugh–Nagumo oscillators modeling neuronal dynamics. All nodes of the remote layers are connected to the hub. The role of the hub and its importance for the existence of chimera states are investigated in dependence on the inter-layer coupling strength and inter-layer time delay. Tongue-like regions in the parameter plane exhibiting double chimeras, i.e., chimera states in the remote layers whose coherent cores are synchronized with each other, and salt-and-pepper states are found. At very low intra-layer coupling strength, when chimera states do not exist in single layers, these may be induced by the hub. Also, the influence of the dilution of links between the remote layers and the hub upon the dynamics is investigated. The greatest effect of dilution is observed when links to the coherent domain of the chimeras are removed.
Slippery surfaces: A decade of progress
Authors: Samaha Mohamed A. , Gad-el-Hak Mohamed
Published: July 2021

Slippery surfaces have received great attention for more than a quarter-century. In particular, during the last decade, interest has increased exponentially, resulting in thousands of articles concerning three types of slippery surfaces: superhydrophobic, superoleophobic, and omniphobic. This review focuses on recent developments and significant findings in naturally inspired slippery surfaces. Superhydrophobicity can be characterized by water droplets beading on a surface at significantly high static contact angles and low contact-angle hystereses. Microscopically rough hydrophobic surfaces could entrap air in their pores, resulting in a portion of a submerged surface with an air–water interface, which is responsible for the slip effect and drag reduction. Suberhydrophobicity enhances the mobility of droplets on lotus leaves for self-cleaning purposes, the so-called lotus effect. Surface hydrophobicity can be advanced to repel low-surface-tension liquids, i.e., become superoleophobic. Another kind of slippery coating is the slippery liquid-infused porous surfaces (SLIPS), which are omniphobic coatings. Certain plants such as the carnivorous Nepenthes pitcher inspired SLIPS. Their interior surfaces have microstructural roughness, which can lock in place an infused lubricating liquid. The lubricant is then utilized as a repellent surface for other liquids or substances such as water, blood, crude oil, ice, insects, and bio-fouling. In this review, we discuss different slippery mechanisms in nature. We also cover recent advances in manufacturing, texturing, and controlling slippery surface at the micro- and nanoscales. We further discuss the performance, sustainability, and longevity of such surfaces under different environmental conditions. Very-recent techniques used to characterize the surfaces are also detailed.