bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrasensitive fluorescence detection of norfloxacin in aqueous medium employing a 2D Zn(ii)-based coordination polymer
Authors: Zeng Na-Na , Ren Li , Cui Guang-Hua
Published: January 2022

A 2D fluorescent coordination polymer, {[Zn(L)0.5(mip)] 1.75H2O}n (1), was successfully assembled. 1 was developed as an ultrasensitive fluorescent probe for the sensing of norfloxacin (NOR) in water.
Towards a quantitative description of excitonic couplings in photosynthetic pigment–protein complexes: quantum chemistry driven multiscale approaches
Authors: Friedl Christian , Fedorov Dmitri G. , Renger Thomas
Published: January 2022

The importance of reaction field and screening effects on the excitonic couplings is demonstrated, and from quantum-chemical calculations a single scaling factor is derived that can be used to improve simple models based on the Poisson equation.
Vibrationally resolved absorption spectra and ultrafast exciton dynamics in α-phase and β-phase zinc phthalocyanine aggregates
Authors: Feng Shishi , Wang Yu-Chen , Liang WanZhen , Zhao Yi
Published: January 2022

Vibrationally resolved absorption spectra in α-phase and β-phase zinc phthalocyanine (ZnPc) aggregates.
Efficient basis sets for core-excited states motivated by Slater's rules
Authors: Qian Jin , Crumlin Ethan J. , Prendergast David
Published: January 2022

Inspired by Slater's rules, we focus on developing computationally efficient and physically motivated contractions to reproduce the core-excited atomic orbitals with improved numerical accuracy of calculated core-electron binding energies (CEBEs).
Molecular understanding of acetylcholinesterase adsorption on functionalized carbon nanotubes for enzymatic biosensors
Authors: Yang Shengjiang , Zhao Daohui , Xu Zhiyong , Yu Hai , Zhou Jian
Published: January 2022

The multi-scale computer simulations exploration of adsorption mechanism of acetylcholinesterase on functionalized carbon nanotubes for enzyme-based organophosphorus pesticides biosensor.
Structural phase transitions in flexible DUT-8(Ni) under high hydrostatic pressure
Authors: Krylov Alexander , Yushina Irina , Slyusareva Evgenia , Krylova Svetlana , Vtyurin Alexander , Kaskel Stefan , Senkovska Irena
Published: January 2022

The structural transformations of the open and closed pore phases of the DUT-8(Ni)) metal–organic framework under high hydrostatic pressures in isopropanol and silicone oil were studied by Raman spectroscopy and numerical simulations.
Effect of CeO2 morphology on the catalytic properties of Au/CeO2 for base-free glucose oxidation
Authors: Qi Xingyue , He Yalin , Yao Yan , Li Yiran , Zhang Lu , Geng Miao , Wei Hang , Chu Haibin
Published: January 2022

The Au/R-CeO2 catalyst with strong metal–support interaction and abundant oxygen vacancies displays superior glucose oxidation performance, as compared with Au/C-CeO2 and Au/O-CeO2.
Time-resolved in situ DRIFTS study on NH3-SCR of NO on a CeO2/TiO2 catalyst
Authors: Yang Jie , Ren Shan , Wang Mingming , Chen Zhichao , Chen Lin , Liu Lian
Published: January 2022

Ce–Ti catalysts were considered as a promising replacement for V–Ti based catalysts for selective catalytic reduction (SCR) of nitrogen oxides (NO and NO2) with NH3.
F,N-Doped carbon dots as efficient Type I photosensitizers for photodynamic therapy
Authors: Wu Xiaoyan , Xu Mingsheng , Wang Shuna , Abbas Khurram , Huang Xin , Zhang Renquan , Tedesco Antonio Claudio , Bi Hong
Published: January 2022

As Type I photosensitizers, fluorine and nitrogen co-doped carbon dots (F,NCDs) can produce highly toxic hydroxyl and superoxide radicals under LED light irradiation, and can be potentially used in the treatment of hypoxic tumor.
Construction of bifunctional electrochemical biosensors for the sensitive detection of the SARS-CoV-2 N-gene based on porphyrin porous organic polymers
Authors: Cui Jing , Kan Lun , Cheng Fang , Liu Jiameng , He Linghao , Xue Yulin , Fang Shaoming , Zhang Zhihong
Published: January 2022

Schematic diagram of the TAPP-DPDD-POP nanostructure as a platform for the immobilization of the N-gene aptamer and N-gene antibody for N-gene detection by the electrochemical method.
CO2 capture by pumping surface acidity to the deep ocean
Authors: Tyka Michael D. , Van Arsdale Christopher , Platt John C.
Published: January 2022

Electrochemically splitting seawater and releasing the acidified effluent stream at depth could be used to artificially accelerate dissolution of deep ocean carbonate sediments and enact CO2 sequestration with storage times of 300–2500 years.
Identification and quantification of anthropogenic nanomaterials in urban rain and runoff using single particle-inductively coupled plasma-time of flight-mass spectrometry
Authors: Wang Jingjing , Nabi MD Mahmudun , Erfani Mahdi , Goharian Erfan , Baalousha Mohammed
Published: January 2022

Urban rain and runoff are potential sources of anthropogenic nanomaterials (engineered and incidental, ENMs and INMs) to receiving waterbodies.
Effect of polycation nanostructures on cell membrane permeability and toxicity
Authors: Wytrwal-Sarna Magdalena , Knobloch Paulina , Lasota Sławomir , Michalik Marta , Nowakowska Maria , Kepczynski Mariusz
Published: January 2022

Amphiphilic polycations with quaternary ammonium groups show a strong tendency to porate lipid membranes. The polycations with a high capacity to open pores in biomembranes are the most cytotoxic to cells.
Design, synthesis and anti-mycobacterial evaluation of imidazo[1,2-a]pyridine analogues
Authors: Khetmalis Yogesh Mahadu , Chitti Surendar , Umarani Wunnava Anjani , Karan Kumar Banoth , Murali Krishna Kumar Muthyala , Murugesan Sankaranarayanan , Chandra Sekhar Kondapalli Venkata Gowri
Published: January 2022

34 imidazo[1,2-a]pyridine amides & sulfonamides are synthesized & evaluated for in vitro anti-TB activity against MTB H37Rv. IPA-6 is most potent with MIC 0.05 μg mL−1 & 125 times active than ethambutol & docked to MTB enoyl acyl protein reductase.
The synergistic effect of CuBi2O4 and Co-Pi: improving the PEC activity of BiVO4-based composite materials
Authors: Liu Rui , Wang Dong , Han Changcun , Wang Pan , Tong Zhengfu , Tan Baohua , Liu Zhifeng
Published: January 2022

Reducing the reaction barrier on the photoelectrode surface and increasing the water oxidation power of the sample surface are the key issues to improve photoelectrochemical water splitting performances.
Remote N–H activation of indole aldehydes: an investigation of the mechanism, origin of selectivities, and role of the catalyst
Authors: Shyam Abhijit , Pradhan Amit Kumar , Mondal Paritosh
Published: January 2022

Density functional theory investigation on the N-heterocyclic carbene-catalysed synthesis of oxazinoindole derivatives via N–H activation of indole aldehydes.
Construction of azaspirocyclic skeletons mediated by the carbonyl of the Weinreb amide: formal total synthesis of (±)-cephalotaxine
Authors: Liu Jianyin , Zhang Jian , Fan Yuxue , Ding Huili , Liu Tianfu , Li Shanshan , Jiang Minghua , Liu Lu
Published: January 2022

A facile Stevens rearrangement of the Weinreb amide and the subsequent key steps mediated by the carbonyl of the Weinreb amide led to the construction of azaspirocyclic skeletons of some typical alkaloids.
Synthesis of renewable alkylated decalins with p-quinone and 2-methyl-2,4-pentanediol
Authors: Liu Chunwei , Hu Yancheng , Li Guangyi , Wang Aiqin , Cong Yu , Wang Xiaodong , Zhang Tao , Li Ning
Published: January 2022

Alkylated decalins were first produced by the dehydration of 2-methyl-2,4-pentanediol, followed by Diels–Alder reaction with p-quinone and the hydrodeoxygenation.
Abundance of beryllium in the Sun and stars: The role of non-local thermodynamic equilibrium effects
Authors: Korotin S. , Kučinskas A.
Published: January 2022

Context. Earlier studies have suggested that deviations from the local thermodynamic equilibrium (LTE) play a minor role in the formation of Be II 313 nm resonance lines in solar and stellar atmospheres. Recent improvements in the atomic data allow a more complete model atom of Be to be constructed and the validity of these claims to be reassessed using more up-to-date atomic physics.

Aims. The main goal of this study therefore is to refocus on the role of non-local thermodynamic equilibrium (NLTE) effects in the formation of Be II 313.04 and 313.11 nm resonance lines in solar and stellar atmospheres.

Methods. For this, we constructed a model atom of Be using new atomic data that recently became available. The model atom contains 98 levels and 383 radiative transitions of Be I and Be II and uses the most up-to-date collision rates with electrons and hydrogen. This makes it the most complete model atom used to determine 1D NLTE solar Be abundance and to study the role of NLTE effects in the formation of Be II 313 nm resonance lines.

Results. We find that deviations from LTE have a significant influence on the strength of the Be II 313 nm line in solar and stellar atmospheres. For the Sun, we obtained the 1D NLTE Be abundance of A(Be)NLTE = 1.32 ± 0.05, which is in excellent agreement with the meteoritic value of A(Be) = 1.31 ± 0.04. Importantly, we find that NLTE effects become significant in FGK stars. Moreover, there is a pronounced variation in 1D NLTE–LTE abundance corrections with the effective temperature and metallicity. Therefore, contrary to our previous understanding, the obtained results indicate that NLTE effects play an important role in Be line formation in stellar atmospheres and have to be properly taken into account in Be abundance studies, especially in metal-poor stars.
Manie nach COVID-19-Infektion
Authors: Kozian Ralf , Chaaban Alexandra
Published: January 2022

Wir berichten über die Erstmanifestation einer Manie bei einem 85-jährigen Patienten, der bis dahin zuvor in keiner psychiatrischen Behandlung war. Der Patient war seit 3 Jahren an einer Demenz vom Alzheimer-Typ erkrankt. Die COVID-19-Infektion nahm bei ihm entsprechend der RKI-Leitlinien einen leichten Verlauf. Im Anschluss daran trat ein manisches Syndrom entsprechend der ICD-10 mit einer deutlich gehobenen Stimmung, einer Antriebssteigerung, einem kritikgeminderten Verhalten erstmalig im Leben des Patienten auf.
„Wir waren alle in einer speziellen Situation“ – Die Folgen der COVID-19-Pandemie auf die Spezialisierte ambulante Palliativversorgung
Authors: Kaiser Ulrich , Vehling-Kaiser Ursula , Kalteis Martin , Hoffmann Ana , Schmidt Jörg , Kaiser Florian
Published: January 2022

Ziel der Studie Die Folgen der Covid-19-Pandemie (z. B. Schutzmaßnahmen, digitale Kommunikation) auf die Versorgungsrealität in der SAPV sollen aus Sicht von Mitarbeitern aus SAPV, Pflegeheimen und Hospizen untersucht werden.

Methodik Insgesamt wurden jeweils 10 Mitarbeiter aus einer SAPV bzw. Leitungskräfte von Pflegeheimen/Hospiz mittels qualitativer Leitfadeninterviews befragt. Die Auswertung erfolgt mittels qualitativer Inhaltsanalyse nach Mayring.

Ergebnisse Neue Schutzmaßnahmen waren für das SAPV-Team sehr bedeutsam. In der SAPV treten Belastungen v. a. durch Abstandsregelungen und erhöhte Arbeitsbelastungen auf. Zu digitalen Kommunikationsformen äußerte sich die Mehrzahl der Befragten positiv, persönlicher Kontakt (zu Patienten/zwischen Fachpersonal) bleibt wichtig.

Schlussfolgerung Schutzmaßnahmen führen im Bereich Patientenversorgung und im Team zur Mehrbelastung, vermitteln aber Sicherheit und tragen zur Stressreduktion bei. COVID-19 kann zur Diagnoseverschiebung in der SAPV und zur engeren Zusammenarbeit mit Hausärzten führen.
Weiterbildung Notfallpflege am Beispiel von Berlin
Authors: Dormann Patrick
Published: January 2022

Ergänzend zur Weiterbildung Notfallpflege nach den curricularen Empfehlungen der DKG in der intensiv 06/2021 stellen Mareen Machner und Patrick Dorman nun die Fachweiterbildung „Pflegende in Einrichtungen der Notfallpflege“ aus Berlin vor. Dieser Lehrgang ist, neben der Bremer Weiterbildung, die einzige landesrechtlich anerkannte Fachweiterbildung Notfallpflege in Deutschland.
Klinik Unternehmen: Auf-/Absteiger des Monats
Authors: Schmidt Hartmut
Published: January 2022

Börsenexperte Hartmut Schmidt analysiert für kma die Jahresabschlüsse ausgewählter Kliniken.
Fehlerkultur im Klinikalltag: Irren ist menschlich
Authors: Hohnstein Aileen
Published: January 2022

Mangelnde Kommunikation, viel Stress und fehlende Einarbeitung – wenn im Krankenhaus Fehler passieren, ist selten einer allein dafür verantwortlich. Wir haben mit Klinikärztinnen darüber gesprochen, ob Fehlerkultur in ihrem Berufsalltag eine Rolle spielt, welche Erfahrungen sie selbst in ihrem Beruf im Umgang mit Fehlern gesammelt haben und was sich für sie ändern müsste.
Strategische Planung: Szenarioanalyse statt Blick in die Glaskugel
Authors: Schicketanz Thomas
Published: January 2022

Mit strategischer Planung über fünf und mehr Jahre beschäftigen sich Klinikmanager bislang eher selten. Szenarioanalysen können es ihnen leicht(er) machen. Sie zeigen, welche Auswirkungen die Variation wesentlicher Einflussfaktoren auf das Haus, die Abteilungen und auf Kostenarten haben kann. Mit diesem Wissen können die Verantwortlichen Alternativen durchspielen und quantifizieren sowie zeitnah entscheiden.
Digitale Dokumentation: Basisanamnese und Entlassberichte neu gedacht
Authors: Spinner Christoph D. , Henkel Andreas G. , Knipfer Eva , Bauer Jens
Published: January 2022

Die ärztliche Dokumentation ist wesentlicher Bestandteil der stationären Diagnostik und Therapie. Wie strukturierte digitale Entlassberichte mit einer vollständig digitalen Workflow-Steuerung und ohne großen Ressourceneinsatz erstellt werden können, zeigt ein Beispiel des Klinikums rechts der Isar (MRI).
Neue Ransomware-Varianten: Das Gesundheitswesen im Visier
Authors: Börner Kevin
Published: January 2022

Die Gesundheitsbranche weiß mit vielen Viren und Krankheiten umzugehen, doch gegen Ransomware ist auch sie nicht immun. Jene Angriffe haben die Gesundheitsbranche im Jahr 2020 rund 18 Milliarden Euro gekostet. Dabei sind 92 Angriffe bekannt, die sich auf mehr als 600 verschiedene Gesundheitsorganisationen auswirkten und mehr als 18 Millionen Patientendaten gefährdeten.
Finanzlage der Unikliniken: „Versorgungszuschlag bildet Aufwand nicht ab“
Authors: Doelfs Guntram
Published: January 2022

Die deutschen Unikliniken haben 2020 ein deftiges Minus von 544 Millionen Euro eingefahren. Ein Gespräch mit Prof. Jens Scholz, Präsident des Verbandes der Universitätskliniken Deutschlands (VUD) über große Belastungen durch Corona, auseinanderdriftende Kosten und Erlöse – und warum das Minus 2021 noch höher ausfallen könnte.
Medizintechnik-Finanzierung: Die Qual der Wahl
Authors: Lang Michael
Published: January 2022

Bei der Beschaffung von Medizintechnik können Krankenhäuser zwischen unterschiedlichen Finanzierungsmodellen wählen. Durch eine flexible Vertragsgestaltung erhalten die Kliniken in der Regel ein Angebot, das exakt auf ihre Bedürfnisse zugeschnitten ist.
DGIV Nachrichten: Maßnahmen ergreifen - sich nicht wegducken
Authors: Nagel Eckhard
Published: January 2022

Die vierte Welle der Corona-Pandemie ist gekommen. Mit ihren schwerwiegenden Erkrankungen und ihrer besonders komplexen und variablen Form der Dissemination wirkt diese sich auf alle Lebensbereiche der Bevölkerung weltweit aus – mit gravierenden Folgen.
Photothermal AFM-IR spectroscopy and imaging: Status, challenges, and trends
Authors: Mathurin Jeremie , Deniset-Besseau Ariane , Bazin Dominique , Dartois Emmanuel , Wagner Martin , Dazzi Alexandre
Published: January 2022

This article focuses on the atomic force microscopy-infrared (AFM-IR) technique and its recent technological developments. Based on the detection of the photothermal sample expansion signal, AFM-IR combines the high spatial resolution of atomic force microscopy with the chemical identification capability of infrared spectroscopy to achieve submicrometric physico-chemical analyses. Since the first publication in 2005, technological improvements have dramatically advanced the capabilities of AFM-IR in terms of spatial and spectral resolution, sensitivity, and fields of applications. The goal of this paper is to provide an overview of these developments and ongoing limitations. We summarize recent progress in AFM-IR implementations based on the major AFM contact, tapping, and peak force tapping modes. Additionally, three new trends are presented, namely, AFM-IR applied to mineral samples, in fluid and a novel, purely surface sensitive AFM-IR configuration, to probe top layers. These trends demonstrate the immense potential of the technique and offer a good insight into the scope of AFM-IR.
Analysis of super-resolution single molecule localization microscopy data: A tutorial
Authors: Fazel Mohamadreza , Wester Michael J.
Published: January 2022

The diffraction of light imposes a fundamental limit on the resolution of light microscopes. This limit can be circumvented by creating and exploiting independent behaviors of the sample at length scales below the diffraction limit. In super-resolution single molecule localization microscopy (SMLM), the independence arises from individual fluorescent labels stochastically switching between dark and fluorescent states, which in turn allows the pinpointing of fluorophores post experimentally using a sequence of acquired sparse image frames. Finally, the resulting list of fluorophore coordinates is utilized to produce high resolution images or to gain quantitative insight into the underlying biological structures. Therefore, image processing and post-processing are essential stages of SMLM. Here, we review the latest progress on SMLM data processing and post-processing.
Positron charge sensing using a double-gated graphene field effect transistor
Authors: Or Paz , Devidas T. R. , Taniguchi Takashi , Watanabe Kenji , Sabo-Napadesky Iris , May-Tal Beck Sharon , Ron Guy , Steinberg Hadar
Published: January 2022

We utilize a high-mobility double-gated graphene field-effect transistor to measure the accumulated charge created by positron annihilation in its back-gate. The device consists of an exfoliated graphene flake stacked between two hexagonal boron nitride flakes placed on a 1 cm2 substrate of 500 μm thick conducting p-doped Si capped by 285 nm-thick SiO2. The device is placed in close proximity to a 780 kBq 22Na positron source emitting a constant flux of positrons. During the measurement, positrons annihilate within the back-gate, kept floating using a low-capacitance relay. The accumulated positive charge capacitively couples to the graphene device and builds a positive voltage, detectable through a shift in the top-gate dependent graphene resistance characteristic. The shift in the position of the top-gate Dirac peak is then used for extracting the exact voltage buildup and quantitative evaluation of the accumulated charge. Reaching a positron current sensitivity of ∼1.2 fA/Hz, detected over 20 min, our results demonstrate the utility of two-dimensional layered materials as probes for charging dynamics of positrons in solids.
Design of strongly nonlinear graphene nanoelectromechanical systems in quantum regime
Authors: Lee Jaesung , LaHaye Matthew D. , Feng Philip X.-L.
Published: January 2022

We report on the analysis and design of atomically thin graphene resonant nanoelectromechanical systems (NEMS) that can be engineered to exhibit anharmonicity in the quantum regime. Analysis of graphene two-dimensional (2D) NEMS resonators suggests that with device lateral size scaled down to ∼10–30 nm, restoring force due to the third-order (Duffing) stiffness in graphene NEMS can rise to equal or even exceed the force of linear stiffness, enabling strongly nonlinear NEMS resonators with anharmonic potential energy that produces sufficient deviation from a quantum harmonic spectrum, which is necessary toward realizing NEMS qubits. Furthermore, the calculations provide device design guidelines and scaling of anharmonicity in graphene NEMS to facilitate future fabrication of graphene NEMS qubits with the desired nonlinear dynamical characteristics and performance. The results in this work shall help open possibilities for engineering a new type of qubits based on 2D resonant NEMS, which may offer a much more miniaturized, densely packed, and scalable qubit platform, supplementing today's mainstream technologies such as superconducting and trapped ion qubits.
A unified thermionic and thermionic-field emission (TE–TFE) model for ideal Schottky reverse-bias leakage current
Authors: Li W. , Jena D. , Xing H. G.
Published: January 2022

We present a unified thermionic emission (TE) and thermionic-field emission (TFE) model for the ideal reverse-bias leakage current in Schottky junctions. The unified TE–TFE analytical model advances upon previous analytical TFE models by Murphy–Good and Padovani–Stratton, which are the two most widely adopted models by the community, in two major aspects: (i) the applicability of the TFE expression therein is extended to near-zero surface electric fields by an error-function correction, allowing for the calculation of the total current by a nontrivial sum of TE (over-the-barrier current) and TFE (below-the-barrier current) contributions; therefore, an accurate description of the TE-to-TFE transition region is captured analytically for the first time; (ii) image-force lowering is considered with much-simpler correction terms. Comparisons with the reference numerical model show that the unified TE–TFE model has excellent accuracy, as well as a 10 000× reduction in computation time. The unified model is further tested against experimental data from Schottky barrier diodes based on Si, 4H-SiC, GaN, and β-Ga2O3, revealing accurate extractions of barrier heights and correct descriptions of the ideal reverse leakage characteristics. With the extended applicable range, improved accuracy, and computational efficiency, the unified TE–TFE model is highly valuable for the design and analysis of devices based on Schottky junctions, as well as for potential integration in technology computer-aided design (TCAD) tools.
Shock response of pre-existing spall damage in copper
Authors: Chen Pengyu , Wang Xinxin , Wang Pei , He An-Min
Published: January 2022

We perform molecular dynamics simulations to investigate second-shock-induced recompaction and the subsequent re-spallation process in Cu with pre-existing spall damage. Compared with the conventional spalling of pristine Cu free of damage, a clear disturbance is observed in the free-surface velocity under the second shock of a pre-spalled Cu sample. This is due to the complex interactions of shock waves during the collapse of existing voids. Full recompaction accompanied by local melting of residual damage is also observed in our second-shock simulations. Secondary spallation occurs after the recompaction process, and the effect of secondary loading conditions, including different values of the peak shock pressure and different flat-top widths of the shock wave, on second spallation is taken into account. The findings clearly show that the spall strength of pre-spalled Cu is lower than that of pristine Cu under the same loading conditions when the loading time is sufficiently long. This result is evidence of the locally disordered state of the recovered sample. Re-solidification accompanied by atomic rearrangement is observed in the disordered region after second-shock compression.
Plasma parameters measured inside and outside a microwave-discharge-based plasma cathode using laser-induced fluorescence spectroscopy
Authors: Morishita Takato , Tsukizaki Ryudo , Nishiyama Kazutaka , Kuninaka Hitoshi
Published: January 2022

An understanding of the plasma physics inside a microwave discharge cathode is key to extending the lifetime of microwave ion thruster systems. However, probes can only measure the plume region due to their low spatial resolution and electromagnetic disturbance. In this study, we develop a microwave discharge-based cathode with a small optical window in the discharge chamber that provides visual access to the cathode interior. The cathode has the same anode currents as those of a flight model in the diode mode (anode voltage error is within 7%). Laser-induced fluorescence spectroscopy is applied to the cathode. The axial and radial ion velocity distribution functions (IVDFs) in the plume region and the axial IVDFs inside the cathode are measured. The measured functions, which represent the number density of Xe II (3P2)6p[3]5/2, are compared to a previously reported number density of Xe II measured by an electrostatic probe in the plume region. The functions exhibit multimodal characteristics. Theoretical models based on the measured current oscillation support these characteristics.
Space-reconfigurable reflector with auxetic lattice material
Authors: Xu Bin , Fang Houfei , Cai Guoping , Hou Yangqing , Jiang Shuidong , Lan Lan , Liu Pengo
Published: January 2022

A mechanically reconfigurable reflector (MRR) can adapt its geometry to facilitate a space antenna’s ability to scan along different angles. The reflector geometries corresponding to various scanning angles are calculated by coordinate change. The proper mechanical properties of the MRR are important for reconfiguration accuracy and actuation of the reflector system. The ratio of bending stiffness to Young’s modulus (D/E) is an essential parameter for the smooth reshaping of the MRR. In previous MMR research, materials with a small Young’s modulus were used, and the D/E ratio is increased by increasing shell thickness. In order to increase the D/E ratio while maintaining a thinner shell thickness, this paper proposes an auxetic lattice material for a reconfigurable reflector shell. The auxetic lattice material allows the raw material of the reflector shell to have a high Young’s modulus resulting in a smaller thickness. By optimizing the stacking sequence of carbon fiber composite, the bending stiffness of raw material is improved. Compounding the stacking sequence with elliptic voids array structure in reflector shell, the in-plane effective Young’s modulus is significantly decreased while maintaining a small decrease in bending stiffness. For a given target shape, the geometric parameters of the elliptic void are determined by the comparison of the reshaping accuracy calculated through simulation.
Structural, electrical, and luminescence properties of (0001) ZnO epitaxial layers grown on c-GaN/sapphire templates by pulsed laser deposition technique
Authors: Simran  , Yadav Santosh Kumar , Chakrabarti Poulab , Dhar Subhabrata
Published: January 2022

A systematic study of growth, structural, electrical, and luminescence properties of zinc oxide (ZnO) layers grown on c-oriented GaN/sapphire templates by the pulsed laser deposition technique is carried out. A thorough high-resolution x-ray diffraction study reveals that c-ZnO films with high crystalline quality can be grown under certain growth conditions. Screw and edge dislocation densities in these films are found to be as low as 7×108 and 3×1010cm−2, respectively. All layers are found to be unintentionally n-type with ∼1019cm−3 electron concentration and mobility as high as ∼50 cm2 V−1 s−1. Temperature and excitation intensity dependent photoluminescence (PL) studies as functions of the growth conditions are carried out to identify the transition processes behind various luminescence features found in these samples. At low temperatures, PL spectra are marked by sharp neutral donor bound excitonic transitions, their phonon replicas, and two broad luminescence bands at 2.2 and 2.9 eV. These broad bands are attributed to transitions from the (2+/0) oxygen vacancy (VO) and (2+/+/0) zinc-interstitial (Zni) levels, respectively, to the valence band. Thermal energy needed to depopulate these defects is found to be 11 and 385 meV, respectively, for the (2+/0) VO and (2+/+/0) Zni levels. Low temperature PL spectra for the samples grown with relatively high oxygen pressures are featured by the Zn-vacancy (VZn) related neutral acceptor bound excitonic transition, its phonon replicas, and a broad band at 2.75 eV. This band diminishes with increasing temperature and, instead, another broad feature appears at ∼2.1 eV. Our study attributes the 2.75 eV band to transition from the conduction band to (0/−) VZn levels and the 2.1 eV feature to the transition between (−/2−) VZn levels and the valence band. It has been found that all the defect related features can be minimized by adjusting the growth conditions.
A superior Na3V2(PO4)3-based cathode enhanced by Nb-doping for high-performance sodium-ion battery
Authors: Rao Xianhui , Wang Jie , Yang Min-An , Zhao Hailei , Li Zhaolin
Published: January 2022

Na3V2(PO4)3 has been considered as the most promising cathode material for sodium-ion batteries because of its suitable sodium insertion/extraction plateau and good cycling stability. However, the inferior rate-capability resulting from the lower electronic conductivity restricts its commercial application. To address this issue, niobium ions (Nb5+) are introduced to partially substitute V3+ for generating V-mixed valence, ensuring the material with improved intrinsic electronic conductivity. Herein, nano-sized Na3V2−xNbx(PO4)3/C (x = 0, 0.05, 0.1, 0.2) materials with a core–shell structure are prepared via a simple sol–gel method. The optimized Na3V1.9Nb0.1(PO4)3/C material shows a high specific capacity (∼114 mA h g−1 at 0.5C), a superior rate-capability (∼100 mA h g−1 at 20C), and an excellent long-term cycling stability (a specific capacity of 74.7 mA h g−1 over 1000 cycles at 50C, corresponding to a capacity decay rate of 0.0258%/cycle). The improved cycling performance is mainly attributed to the enhanced intrinsic electronic conductivity and Na+ mobility, and the reduced charge-transfer resistance, as confirmed by the first-principles calculations, cyclic voltammetry, and electrochemical impedance spectra analysis. The constructed fast electron network, from the surface to the bulk, combining with the nano-sized feature, contributes to the facilitated electrode reaction kinetics and, thus, ensures improved rate-capability.
Lattice-plasmon-induced asymmetric transmission in two-dimensional chiral arrays
Authors: Apurv Chaitanya N. , Butt M. A. T. , Reshef O. , Boyd Robert W. , Banzer P. , De Leon Israel
Published: January 2022

Asymmetric transmission—direction-selective electromagnetic transmission between two ports—is a phenomenon exhibited by two-dimensional chiral systems. The possibility of exploiting this phenomenon in chiral metasurfaces opens exciting possibilities for applications such as optical isolation and routing without external magnetic fields. This work investigates optical asymmetric transmission in chiral plasmonic metasurfaces supporting lattice plasmon modes and unveils its physical origins. We show numerically and experimentally that asymmetric transmission is caused by an unbalanced excitation of such lattice modes by circularly polarized light of opposite handedness. The excitation efficiencies of the lattice modes, and hence, the strength of the asymmetric transmission, are controlled by engineering the in-plane scattering of the individual plasmonic nanoparticles such that the maximum scattering imbalance occurs along one of the in-plane diffraction orders of the metasurface. Furthermore, we show that only the nonzero diffraction orders contribute to this effect. By highlighting the role of the localized plasmon modes supported by the nanoparticle and their radiative coupling to the lattice structure, our study provides a guideline for designing metasurfaces with asymmetric transmission enabled by lattice plasmons.
Adsorption-active polydisperse brush with tunable molecular mass distribution
Authors: Ivanova Anna S. , Polotsky Alexey A. , Skvortsov Alexander M. , Klushin Leonid I. , Schmid Friederike
Published: January 2022

Recently, a novel class of responsive uncharged polymer brushes has been proposed [Klushin et al., J. Chem. Phys. 154(7), 074904 (2021)] where the brush-forming chains have an affinity to the substrate. For sufficiently strong surface interactions, a fraction of chains condenses into a near-surface layer, while the remaining ones form the outer brush with a reduced grafting density. The dense layer and the more tenuous outer brush can be seen as coexisting microphases. The effective grafting density of the outer brush is controlled by the adsorption strength and can be changed reversibly as a response to changes in environmental parameters. In this paper, we use numerical self-consistent field calculations to study this phenomenon in polydisperse brushes. Our results reveal an unexpected effect: Although all chains are chemically identical, shorter chains are adsorbed preferentially. Hence, with the increase in the surface affinity parameter, a reduction in the surface grafting density of the residual brush is accompanied by a change in the shape of its molecular mass distribution (MMD). In particular, an originally bidisperse brush can be effectively transformed into a nearly monodisperse one containing only the longer chain fraction. We introduce a method of assigning different chain conformations to one or the other microphase, based on analyzing tail length distributions. In a polydisperse brush with a uniform MMD, short chains are relegated to the adsorbed phase, leading to a narrower effective MMD in the residual brush. Preferential adsorption is not absolute, and longer chains are also partially involved in adsorption. As a result, not only the width of the distribution decreases but also its shape evolves away from the initial uniform distribution. We believe that the effect of preferential adsorption stems from a fundamental property of a polydisperse brush, which is characterized by a spectrum of chemical potential values for monomers belonging to chains of different lengths. Hence, preferential adsorption is also expected in polyelectrolyte brushes; moreover, brush polydispersity would affect coexistence with any other condensed phase, not necessarily related to adsorption.
Interaction potential for coarse-grained models of bottlebrush polymers
Authors: Pan Tianyuan , Dutta Sarit , Sing Charles E.
Published: January 2022

Bottlebrush polymers are a class of highly branched macromolecules that show promise for applications such as self-assembled photonic materials and tunable elastomers. However, computational studies of bottlebrush polymer solutions and melts remain challenging due to the high computational cost involved in explicitly accounting for the presence of side chains. Here, we consider a coarse-grained molecular model of bottlebrush polymers where the side chains are modeled implicitly, with the aim of expediting simulations by accessing longer length and time scales. The key ingredients of this model are the size of a coarse-grained segment and a suitably coarse-grained interaction potential between the non-bonded segments. Prior studies have not focused on developing explicit forms of such potentials, instead, relying on scaling arguments to model non-bonded interactions. Here, we show how to systematically calculate an interaction potential between the coarse-grained segments of bottlebrush from finer grained explicit side chain models using Monte Carlo and Brownian dynamics and then incorporate it into an implicit side chain model. We compare the predictions from our coarse-grained implicit side chain model with those obtained from models with explicit side chains in terms of the potential of mean force, the osmotic second virial coefficient, and the interpenetration function, highlighting the range of applicability and limitations of the coarse-grained representation. Although presented in the context of homopolymer bottlebrushes in athermal solvents, our proposed method can be extended to other solvent conditions as well as to different monomer chemistries. We expect that our implicit side chain model will prove useful for accelerating large-scale simulations of bottlebrush solutions and assembly.
Analysis of the Urbach tail in cesium lead halide perovskites
Authors: Falsini Naomi , Roini Giammarco , Ristori Andrea , Calisi Nicola , Biccari Francesco , Vinattieri Anna
Published: January 2022

The role of structural and dynamical disorder in semiconductors is a topic of fundamental relevance because of its contribution to the spectral line shape of the photoluminescence, and it plays a major role in ruling the carrier transport properties at the band edge. In this regard, a class of semiconductors, i.e., halide perovskites, deeply investigated in the last decade, shows a peculiar degree of disorder, which has only been recently under investigation. The interest to study disorder in halide perovskites is related to the large set of innovative applications of this class of materials, spanning from energy harvesting to high brilliance incoherent and coherent light emitters. In this perspective, we show that quantitative information on the disorder in halide perovskites can be extracted by deep analysis of the photoluminescence in different experimental conditions. Our study, conducted on a large set of samples of a metal halide perovskite, CsPbBr3, prepared with various synthesis/deposition methods, clarifies the relative weight of the static and dynamic contributions. A comparison with theoretical predictions is provided, gaining insights into the exciton/carrier–phonon interaction in metal halide perovskites.
Connecting density fluctuations and Kirkwood–Buff integrals for finite-size systems
Authors: Sevilla Mauricio , Cortes-Huerto Robinson
Published: January 2022

Kirkwood–Buff integrals (KBIs) connect the microscopic structure and thermodynamic properties of liquid solutions. KBIs are defined in the grand canonical ensemble and evaluated by assuming the thermodynamic limit (TL). In order to reconcile analytical and numerical approaches, finite-size KBIs have been proposed in the literature, resulting in two strategies to obtain their TL values from computer simulations. (i) The spatial block analysis method in which the simulation box is divided into subdomains of volume V to compute density fluctuations. (ii) A direct integration method where a corrected radial distribution function and a kernel that accounts for the geometry of the integration subvolumes are combined to obtain KBI as a function of V. In this work, we propose a method that connects both strategies into a single framework. We start from the definition of finite-size KBI, including the integration subdomain and an asymptotic correction to the radial distribution function, and solve them in Fourier space where periodic boundary conditions are trivially introduced. The limit q → 0, equivalent to the value of the KBI in the TL, is obtained via the spatial block-analysis method. When compared to the latter, our approach gives nearly identical results for all values of V. Moreover, all finite-size effect contributions (ensemble, finite-integration domains, and periodic boundary conditions) are easily identifiable in the calculation. This feature allows us to analyze finite-size effects independently and extrapolates the results of a single simulation to different box sizes. To validate our approach, we investigate prototypical systems, including SPC/E water and aqueous urea mixtures.
Fabrication of 2D perovskite (PMA)2PbI4 crystal and Cu ion implantation improved x-ray detector
Authors: Qian Chong-Xin , Wang Ming-Zi , Lu Shan-Shan , Feng Hong-Jian
Published: January 2022

Two-dimensional (2D) perovskites have been demonstrated great promise in x-ray detection application because of their stability, tunability, and the unique electronic properties. The centimeter-sized 2D perovskite (PMA)2PbI4 single crystal and the corresponding x-ray detector were fabricated. The Cu ion implanted device exhibits an excellent sensitivity of 283 μC Gyair−1 cm−2, the significantly enhanced mobility-lifetime (μτ) product of 8.05 × 10−3 cm2 V−1, and the lowest detectable dose rate of 2.13 μGyair s−1. Experimental observation combined with the DFT calculations shows that the improvement in Cu ion implanted x-ray detection is ascribed to the enhanced photoinduced charge carrier density and μτ product, and the increased carrier dissociation capability associated deeply with the decreased binding energy of exciton in the inorganic layer quasi-quantum well. The incorporation of the Cu interstitials by high-energy Cu ion implantation is able to introduce the donor and acceptor states with additional charge transfer channeling, resulting in the decreased exciton binding energy and fast dissociation of the exciton and the quick carrier extraction. Cu ion implantation regulating the dissociation of charge carriers in low-dimensional perovskites will motivate the application for 2D perovskite in high-performance x-ray detectors.
Excitation localization in a trimeric perylenediimide macrocycle: Synthesis, theory, and single molecule spectroscopy
Authors: Hauschildt Simon J. , Wu Zehua , Uersfeld Daniel , Schmid Paul , Götz Christian , Engel Volker , Engels Bernd , Müllen Klaus , Basché Thomas
Published: January 2022

A novel trimeric perylenediimide (PDI) macrocycle was synthesized, and its intramolecular electronic couplings were investigated by bulk and single-molecule optical spectroscopy and by various theoretical approaches. In polarization-resolved excitation spectroscopy at 1.2 K in a PMMA matrix, the appearance and disappearance of the three zero-phonon lines (ZPLs) of an individual trimer by changing the polarization in steps of 60° nicely reflect an approximate triangular geometry of the macrocycle and indicate localized excitations that are transferred by incoherent hopping processes at time scales of around 1 ps as inferred from the ZPL linewidths. The electronic coupling strength deduced from the low temperature data is found to be in good agreement with theoretical estimates. Bulk spectroscopy in toluene at room temperature indicates that the excitations are also localized under these conditions. Theory reveals that the reasons for the localized nature of the excitations at room and low temperatures are different. For a rigid macrocycle, the excitations are predicted to be delocalized, but molecular dynamics simulations point to considerable structural flexibility at ambient temperatures, which counteracts excitation delocalization. At 1.2 K in a PMMA matrix, this effect is too small to lead to localization. Yet, supported by simple model calculations, the disorder in the PMMA host induces sufficient differences between the PDI chromophores, which again result in localized excitations. By addressing crucial aspects of excitation energy transfer, our combined approach provides a detailed and quantitative account of the interchromophore communication in a trimeric macrocycle.
Platinum nanoparticle compression: Combining in situ TEM and atomistic modeling
Authors: Padilla Espinosa Ingrid M. , Azadehranjbar Soodabeh , Ding Ruikang , Baker Andrew J. , Jacobs Tevis D. B. , Martini Ashlie
Published: January 2022

The mechanical behavior of nanoparticles governs their performance and stability in many applications. However, the small sizes of technologically relevant nanoparticles, with diameters in the range of 10 nm or less, significantly complicate experimental examination. These small nanoparticles are difficult to manipulate onto commercial test platforms and deform at loads that are below the typical noise floor of the testing instruments. Here, we synthesized small platinum nanoparticles directly onto a mechanical tester and used a modified nanomanipulator to enhance load resolution to the nanonewton scale. We demonstrated the in situ compression of an 11.5-nm platinum nanoparticle with simultaneous high-resolution measurements of load and particle morphology. Molecular dynamics simulations were performed on similarly sized particles to achieve complementary measurements of load and morphology, along with atomic resolution of dislocations. The experimental and simulation results revealed comparable values for the critical resolved shear stress for failure, 1.28 and 1.15 GPa, respectively. Overall, this investigation demonstrated the promise of, and some initial results from, the combination of atomistic simulations and in situ experiments with an unprecedented combination of high spatial resolution and high load resolution to understand the behavior of metal nanoparticles under compression.
Cell morphologies, mechanical properties, and fiber orientation of glass fiber-reinforced polyamide composites: Influence of subcritical gas-laden pellet injection molding foaming technology
Authors: Yang Huaguang , Román Allen Jonathan , Chang Tzu-Chuan , Yu Chenglong , Jiang Jing , Shotwell Demitri , Chen Edward , Osswald Tim A. , Turng Lih-Sheng
Published: January 2022

Advanced materials and new lightweighting technologies are essential for boosting the fuel economy of modern automobiles while maintaining performance and safety. A novel approach called subcritical gas-laden pellet injection molding foaming technology (SIFT) was performed to produce foamed polyamide/glass fiber (PA/GF) composite. Gas-laden pellets loaded with nitrogen (N2) were produced by introducing sub-critical N2 into PA/GF composite during compounding using a twin-screw extruder equipped with a simple gas injection unit. Compared to the commercial microcellular injection molding (MIM) technologies, gas-laden pellets enable the production of foamed parts with a standard injection molding machine, which is more cost-effective and easier to implement. To the best of our knowledge, this is the first attempt that the SIFT technology is being used for the PA/GF composites for making foamed parts. The tensile strength, fiber orientation, cell morphology, and densities of foamed PA/GF parts were investigated, and the shelf life of N2-laden PA/GF pellets was examined. Results showed that the N2-laden pellets still possessed good foaming ability after one week of storage under ambient atmospheric conditions. One week is a noticeable improvement compared to those N2-laden neat polymer pellets without glass fibers. With this approach, the weight reduction of foamed PA/GF parts was able to reach 12.0 wt. %. Additionally, a nondestructive analysis of the fiber orientation using micro-computed tomography suggested that the MIM and SIFT samples exhibited a less degree of fiber orientation along the flow direction when compared to the solid samples and that the tensile strength of both technologies was very close at a similar weight reduction. Cell size increased and cell density decreased as the shelf life increased. These findings showed that this processing method could act as an alternative to current commercial foam injection molding technology for producing lightweight parts with greater design freedom.
A perspective on conducting domain walls and possibilities for ephemeral electronics
Authors: Gregg J. M.
Published: January 2022

This Perspective briefly summarizes what is known about electrically conducting domain walls. It highlights insights into the underlying causes of enhanced current transport, developed despite the frustrations and limitations of the standard two-probe source and drain measurements that have dominated the field to date (because of the pervasive use of conventional conducting atomic force microscopy). This perspective gives a feel for the unique possibilities offered by conducting domain walls, in future forms of agile electronics. Indeed, it is imagined that domain walls and domain wall junctions might eventually allow for entire nanoscale circuits (devices and their interconnects) to be created in one instant, for one purpose, only to be wiped clean and rewritten in a different form, for a different purpose, in the next instant. Malleable domain wall network architecture that can continually metamorphose could represent a kind of technological genie, granting wishes on demand for radical moment-to-moment changes in electronic function.