bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessment of Loosening and Rotational Malalignment Following Knee Endoprosthesis or Other Surgical Components
Authors: Weber Marc-André , Rehnitz Christoph , Mittelmeier Wolfram , Carrino John , Thierfelder Kolja , Gemescu Ioan
Published: August 2018

Total knee arthroplasty (TKA) has significant medical and economic implications. The correct placement of the femoral and tibial components is vital to ensure a functional knee and also low failure and revision surgery rates. This article provides the most relevant information regarding knee endoprosthesis from a radiologic point of view. Basic information on the recommended alignment of the femoral and tibial components in TKA and how to measure them are discussed. We then present the most important axial plane rotational references for the femoral and the tibial components. The optimal coronal alignment, illustrating the axes of the lower limb, and loosening as the major complication are also discussed. Finally, we offer a detailed example of rotational assessment.
Imaging of the Knee and Surrounding Structures Following Tumor Surgery
Authors: Winn Naomi , Lalam Radhesh
Published: August 2018

Limb salvage is a key goal of tumor management around the knee, with surgical, medical, and radiologic treatment options. Primary bone and soft tissue sarcomas are optimally treated in specialist tertiary centers; however, metastatic disease is encountered in all aspects of radiologic practice, with overlap in the management strategies. Both specialist and generalist radiologists therefore need to be familiar with the expected normal appearances following these therapies and be able to recognize potential complications. This review article describes the techniques available for imaging the knee following treatment of bone and soft tissue tumors, with particular reference to artifact reduction. The therapeutic options for managing bone and soft tissue lesion are discussed, with emphasis on imaging appearances. Surgical, medical, and radiologic treatments are described. Complications and their imaging appearances are reviewed including local recurrence of tumor, infection, complications related to metallic implants, postradiation changes, and amputation. Normal imaging appearances and complications following radiologic treatment (namely radiofrequency ablation) of bone and soft tissue tumors are presented.
Mean Platelet Volume and Neutrophil-to-Lymphocyte Ratio May Be Used as Predictors in Febrile Seizures
Authors: Akın Fatih , Türe Esra , Çaksen Hüseyin , Odabaş Dursun , Yazar Abdullah
Published: August 2018

Febrile seizure (FS) is the most frequent seizure disorder in childhood, associated with rapid onset of high fever. Our study aims are (1) to determine if the levels of mean platelet volume (MPV) and neutrophil-to-lymphocyte ratio (NLR) are risk factors for FS and to (2) assess the usefulness of these markers as predictors to distinguish the subgroups of FS. This prospective study includes children with FS, acute febrile illness (AFI) without seizure, and control group. Complete blood count was performed on all participants. The following data were obtained: white blood cell count (WBC), platelet count, MPV, hemoglobin (Hb), absolute neutrophil count (ANC), absolute lymphocyte count (ALC), and NLR. MPV, WBC, ANC, and NLR were significantly increased in patients with AFI and FS compared with controls (p < 0.05). When patients with FS and AFI were compared, only WBC was increased significantly in patients with FS (p < 0.05). WBC, ANC, and NLR were significantly increased in patients with complex FS compared with simple (p < 0.05). Our findings showed that WBC, MPV, ANC, and NLR were higher in children with FS than in the control group. Additionally WBC, ANC, and NLR were found to be higher in children with CFS than in those with simple febrile seizure. Based on the study results, we suggest that only WBC may be used as predictors in children with FS.
Posterior Reversible Encephalopathy Syndrome Complicating Ruptured Appendicitis and Abscess Drainage in a Previously Healthy Pediatric Patient
Authors: Saley Taylor , Barton Alexander , Sood Shawn , Thukaram Roopa
Published: August 2018

In this study, we present the youngest reported case of posterior reversible encephalopathy syndrome (PRES) in the United States, which developed following perforated appendicitis with subsequent peritonitis and intra-abdominal abscess formation. Additionally, we discuss potential physiological factors contributing to her acute neurological deterioration and resultant cerebral vasogenic edema.
Endoprothetik bei Erwachsenen mit juveniler idiopathischer Arthritis
Authors: Haas J.-P. , Arbogast M.
Published: August 2018

Progressive Verlaufsformen der JIA, die durch medikamentöse Behandlung wenig beeinflussbar sind, münden nicht selten in eine endoprothetische Versorgung vor dem fünften Lebensjahrzent. Durch den Beginn im Kindesoder Jugendalter werden Wachstum und physiologische Gelenkentwicklung verändert. Daraus resultierende Bewegungseinschränkungen und Gelenkfehlstellungen beeinflussen Implantatwahl und Weichteilbehand-lung. Schmerzlinderung und Verbesserung der Lebensqualität nach endoprothetischer Versorgung sind beeindruckend. Dennoch ist die Lebensplanung mit Endoprothesen unterschiedlich zu prognostizieren und abhängig vom Implantationsort.
Rationelles Screening bei Nebennierentumoren
Authors: Willenberg Holger , Kupfer Sophie
Published: August 2018

The characterization of adrenal tumors may become difficult for different reasons. Medical imaging is insufficient to establish a diagnosis, clinical symtoms may vary and medication interfers with lab analysis. Furthermore, hormonal measurements gain diagnostic power with endocrine function tests. This article reviews diagnostic and therapeutic strategies in the management of patients with adrenal tumors.
Mortalität und ihre Ursachen in einer deutschen Kohorte mit Typ-1-Diabetes mellitus in einer 20-jährigen Nachbeobachtung: Die JEVIN-Studie
Authors: Heller Tabitha , Kloos Christof , Lehmann Thomas , Schiel Ralf , Lorkowski Stefan , Wolf Gunter , Müller Ulrich , Müller Nicolle
Published: August 2018

Hintergrund und Ziel Die JEVIN-Studie begann 1989/90 als Querschnittsuntersuchung in Jena. Nach einer Nachbeobachtungszeit von über 20 Jahren erfolgte die Bestimmung der Mortalität in der Gruppe der an der JEVIN-Studie teilnehmenden Typ-1-Diabetes-Patienten.

Patienten und Methodik 103 (78,6 %) der 131 Patienten, die seit Beginn an der JEVIN-Studie teilnahmen, konnten untersucht werden. 38 Personen (36,9 %) waren zwischenzeitlich verstorben. Alle im Rahmen der JEVIN-Studie in der elektronischen Patientenakte EMIL® von überlebenden und verstorbenen Teilnehmern dokumentierten Erhebungsdaten sowie Routineuntersuchungen wurden in die Analysen einbezogen. Die Daten der überlebenden wurden mit denen der verstorbenen Teilnehmer verglichen (Nachbeobachtungsdauer: 2166 Personenjahre).

Ergebnisse Die Sterberate betrug 1,75/100 Personenjahre. Die mediane Beobachtungszeit für alle Patienten betrug 23,1 Jahre (Range 0,61 – 26,6 Jahre). Das mittlere Sterbealter lag bei 58,5 Jahren (34,2 – 78,4 Jahre) und die mittlere Diabetesdauer bei 35 Jahren (3,5 – 68,5 Jahre). Als häufigste Todesursachen fanden sich Herz-Kreislauf-Krankheiten (48,2 %, n = 13) und Infektionen (25,9 %, n = 7). Hinsichtlich Alter (p = 0,302), Diabetesdauer (p = 0,371), BMI (p = 0,535), Blutdruck (p = 0,622/0,820), Geschlecht (p = 0,566) und Raucherstatus (p = 0,709) ließen sich keine Unterschiede zwischen überlebenden und verstorbenen Personen nachweisen. Der mittlere HbA1c-Wert im letzten Jahr vor dem Tod oder der letzten Nachuntersuchung war bei den verstorbenen höher als bei den überlebenden Personen (7,5 vs. 7,0 %; p = 0,010). 57,4 % der überlebenden und 87,0 % der verstorbenen Teilnehmer hatten eine Nephropathie (p = 0,012), 79,7 vs. 89,7 % eine Retinopathie (p = 0,241) und 61,4 vs. 63,3 % eine Neuropathie (p = 0,860). Nur für die Nephropathie konnte eine signifikante Assoziation mit einem erhöhten Sterberisiko nachgewiesen werden (HR = 4,208; KI: 1,226 – 14,440; HR = 2,360, KI: 0,696 – 8,004; HR = 0,944, KI: 0,436 – 2,043).

Schlussfolgerung In der JEVIN-Studie war in der Gruppe der Patienten mit Typ-1-Diabetes mellitus nur die diabetische Nephropathie mit einem höheren Sterberisiko assoziiert.
Diversity of inference strategies can enhance the ‘wisdom-of-crowds’ effect
Authors: Fujisaki Itsuki , Honda Hidehito , Ueda Kazuhiro
Published: August 2018

Studies on inference have shown that people use a variety of inference strategies depending on the situation. Despite a great deal of discussion on the use of these strategies at an individual level, very little research has examined how the strategies people use affect group performance. To address this issue, we conducted two computer simulation studies on group decision-making. Our focus was primarily the diversity of strategies used in groups, as previous studies have suggested that diversity plays a critical role in the wisdom of crowds. Therefore, we systematically manipulated the diversity of inference strategies among group members and examined the effect on group performance. In Study 1, we conducted computer simulations using behavioural data from a previous study and found that diversity of strategies could improve group performance. That is, the group whose members used diverse strategies had higher accuracy than groups where all members used an identical strategy. We also investigated how such a phenomenon emerged. In Study 2, we created multiple hypothetical environmental settings and examined the effect. The environmental settings in Study 1 was limited to the ‘kind’ setting, in which correct inferences could be made for most problems by using a certain strategy, and the results of Study 2 showed that the findings of Study 1 could be generalized to other settings. For example, diversity could improve group performance in the ‘wicked’ environment where an inference strategy tends to lead an individual to the wrong answer. We also identified conditions in which the diversity enhanced group performance in each environment. Finally, for Study 1, we conducted additional simulations and discussed the conditions in which diversity would improve group performance more. The contributions to the research on the wisdom of crowds and human inference are discussed.
Pseudomorphic spinel ferrite films with perpendicular anisotropy and low damping
Authors: Budhani R. C. , Emori Satoru , Galazka Zbigniew , Gray Benjamin A. , Schmitt Maxwell , Wisser Jacob J. , Jeon Hyung-Min , Smith Hadley , Shah Piyush , Page Michael R. , McConney Michael E. , Suzuki Yuri , Howe Brandon M.
Published: August 2018

We report on epitaxial thin films of spinel ferrite Ni0.65Zn0.35Fe1.2Al0.8O4 with strain-induced perpendicular magnetic anisotropy (PMA) and low magnetic damping. Static magnetometry and broadband ferromagnetic resonance experiments show a distinct change in the preferred direction of magnetization from in-plane to out-of-plane when the coherent strain in films changes from ∼2% compressive on (001) MgAl2O4 to ∼0.5% tensile on (001) MgGa2O4 substrates. Significant deviations from the spin-only value (2.0) of the g-factor suggest spin-orbit effects and further support our conclusion of strain-driven magnetic anisotropy in these films. The low Gilbert damping parameter of α = 5 × 10−3 in these ferrite films, combined with their PMA, makes them promising for spintronic and frequency-agile microwave device applications.
Interconnected feedback loops among ESRP1, HAS2, and CD44 regulate epithelial-mesenchymal plasticity in cancer
Authors: Jolly Mohit Kumar , Preca Bogdan-Tiberius , Tripathi Satyendra C. , Jia Dongya , George Jason T. , Hanash Samir M. , Brabletz Thomas , Stemmler Marc P. , Maurer Jochen , Levine Herbert
Published: August 2018

Aberrant activation of epithelial-mesenchymal transition (EMT) in carcinoma cells contributes to increased migration and invasion, metastasis, drug resistance, and tumor-initiating capacity. EMT is not always a binary process; rather, cells may exhibit a hybrid epithelial/mesenchymal (E/M) phenotype. ZEB1—a key transcription factor driving EMT—can both induce and maintain a mesenchymal phenotype. Recent studies have identified two novel autocrine feedback loops utilizing epithelial splicing regulatory protein 1 (ESRP1), hyaluronic acid synthase 2 (HAS2), and CD44 which maintain high levels of ZEB1. However, how the crosstalk between these feedback loops alters the dynamics of epithelial-hybrid-mesenchymal transition remains elusive. Here, using an integrated theoretical-experimental framework, we identify that these feedback loops can enable cells to stably maintain a hybrid E/M phenotype. Moreover, computational analysis identifies the regulation of ESRP1 as a crucial node, a prediction that is validated by experiments showing that knockdown of ESRP1 in stable hybrid E/M H1975 cells drives EMT. Finally, in multiple breast cancer datasets, high levels of ESRP1, ESRP1/HAS2, and ESRP1/ZEB1 correlate with poor prognosis, supporting the relevance of ZEB1/ESRP1 and ZEB1/HAS2 axes in tumor progression. Together, our results unravel how these interconnected feedback loops act in concert to regulate ZEB1 levels and to drive the dynamics of epithelial-hybrid-mesenchymal transition.
Sub-picotesla widely tunable atomic magnetometer operating at room-temperature in unshielded environments
Authors: Deans Cameron , Marmugi Luca , Renzoni Ferruccio
Published: August 2018

We report on a single-channel rubidium radio-frequency atomic magnetometer operating in unshielded environments and near room temperature with a measured sensitivity of 130 fT/Hz. We demonstrate consistent, narrow-bandwidth operation across the kHz–MHz band, corresponding to three orders of magnitude of the magnetic field amplitude. A compensation coil system controlled by a feedback loop actively and automatically stabilizes the magnetic field around the sensor. We measure a reduction in the 50 Hz noise contribution by an order of magnitude. The small effective sensor volume, 57 mm3, increases the spatial resolution of the measurements. Low temperature operation, without any magnetic shielding, coupled with the broad tunability, and low beam power, dramatically extends the range of potential field applications for our device.
A versatile facility for investigating field-dependent and mechanical properties of superconducting wires and tapes under cryogenic-electro-magnetic multifields
Authors: Wang Xingzhe , Zhou Youhe , Guan Mingzhi , Xin Canjie
Published: August 2018

To investigate the field-dependent and mechanical properties of superconducting wires and tapes as a function of cryogenic temperature, transport current, and magnetic field, we designed and constructed a versatile facility capable of providing cryogenic-electro-magnetic multifields. The facility comprises several relatively independent systems to acquire multiple fields and explore various properties for superconductors. A superconducting racetrack magnet is manufactured to generate a transverse background field up to 3.5 T in a relatively large space of a homogeneous region of ∅200 mm × H 150 mm. A cryogenic system consisting of a vacuum Dewar vessel with a visible window cooled by two Gifford–McMahon (GM) cryocoolers for providing refrigeration was built to accommodate the background magnet and testing devices, in which one GM cryocooler cools the magnet at an operation temperature of about 4 K and the other maintains a cryogenic environment for specimens in conduction mode with the cryocooler head directly contacting the fixtures. The continuous variations of temperature (4–293 K) and transport current (0–1000 A) in the superconducting wires and tapes that were tested are, respectively, implemented by an integration differentiation temperature control with an optional temperature sweep rate and a DC high-power supply. Most prominently, the facility can measure the field-dependent and mechanical properties for superconducting wires and tapes, which is implemented by a mechanical loading and measuring system equipped with a universal testing machine possessing a specific design of widening and heightening size and a noncontact digital image correlation method with a high-speed, high-resolution CCD camera for real-time recording and full-field deformation of specimens. The preliminary results of tests verify the multifield functionalities of the versatile facility and illustrate the performance of the facility for studying the properties of superconducting wires and tapes as a function of magnetic field, cryogenic temperature, transport current, and mechanical loading.
Enhanced thermoelectric efficiency in topological insulator Bi2Te3 nanoplates via atomic layer deposition-based surface passivation
Authors: Chen Jihan , Kim Jaehyun , Poudel Nirakar , Hou Bingya , Shen Lang , Shi Haotian , Shi Li , Cronin Stephen
Published: August 2018

We report in-plane thermoelectric measurements of Bi2Te3 nanoplates, a typical topological insulator with Dirac-like metallic surface states, grown by chemical vapor deposition. The as-grown flakes exposed to ambient conditions exhibit relatively small thermopowers around −34 μV/K due to unintentional surface doping (e.g., gas adsorption and surface oxidation). After removal of the unintentional surface doping and surface passivation by deposition of 30 nm of Al2O3 using atomic layer deposition (ALD), the Seebeck coefficient of these flakes increases by a factor of 5× to −169 μV/K. Here, we believe that the ALD-based surface passivation can prevent the degradation of the thermoelectric properties caused by gas adsorption and surface oxidation processes, thus, reducing the unintentional doping in the Bi2Te3 and increasing the Seebeck coefficient. The high surface-to-volume ratio of these thin (∼10 nm thick) nanoplates make them especially sensitive to surface doping, which is a common problem among nanomaterials in general. An increase in the sample resistance is also observed after the ALD process, which is consistent with the decrease in doping.
A compact low-cost low-maintenance open architecture mask aligner for fabrication of multilayer microfluidics devices
Authors: Pham Q. L. , Tong N. A. N. , Mathew A. , Basuray S. , Voronov R. S.
Published: August 2018

A custom-built mask aligner (CBMA), which fundamentally covers all the key features of a commercial mask aligner, while being low cost and light weight and having low power consumption and high accuracy, is constructed. The CBMA is composed of a custom high fidelity light emitting diode light source, a vacuum chuck, a mask holder, high-precision translation and rotation stages, and high resolution digital microscopes. The total cost of the system is under $7500, which is over ten times cheaper than a comparable commercial system. It produces a collimated ultraviolet illumination of 1.8–2.0 mW cm−2 over an area of a standard 4-in. wafer, at the plane of photoresist exposure, and the alignment accuracy is characterized to be <3 μm, which is sufficient for most microfluidic applications. Moreover, this manuscript provides detailed descriptions of the procedures needed to fabricate multilayered master molds using our CBMA. Finally, the capabilities of the CBMA are demonstrated by fabricating two- and three-layer masters for micro-scale devices, commonly encountered in biomicrofluidic applications. The former is a flow-free chemical gradient generator, and the latter is an addressable microfluidic stencil. Scanning electron microscopy is used to confirm that the master molds contain the intended features of different heights.
Thermal conductivity reduction in highly doped mesoporous silicon: The effect of nano-crystal formation
Authors: Vega-Flick A. , Pech-May N. W. , Cervantes-Alvarez F. , Estevez J. O. , Alvarado-Gil J. J.
Published: August 2018

The study of heat transfer properties in mesoporous silicon, fabricated from highly doped p-type and n-type silicon wafers, is presented. Measurements were performed by a laser induced transient thermal grating technique, which allowed us to determine the effective (in-plane) thermal conductivity. It is shown that the thermal conductivity undergoes a significant decrease with respect to bulk values mainly due to a reduction of the phonon mean free path of the solid matrix. This reduction can be ascribed to the formation of nano-crystalline domains, which are a consequence of the wet etching fabrication method. Additionally, the in-plane thermal conductivity was analyzed by employing a modified effective medium approach, which includes the phonon mean free path reduction due to the presence of both the nanometric pores and the nano-crystalline domains. The theoretical analysis shows good agreement with our measurements, indicating that the inclusion of phonon mean free path reduction to an effective medium approach is a well-suited method for studying the thermal conductivity of porous silicon.
2D GEM based imaging detector readout capabilities from perspective of intense soft x-ray plasma radiation
Authors: Chernyshova M. , Czarski T. , Malinowski K. , Melikhov Y. , Kasprowicz G. , Kowalska-Strzęciwilk E. , Linczuk P. , Wojeński A. , Krawczyk R. D.
Published: August 2018

A detecting system based on the Gas Electron Multiplier (GEM) technology is considered for tokamak plasma radiation monitoring. In order to estimate its capabilities in processing and recording intense photon flux (up to ∼0.1 MHz/mm2), the imaging effectiveness of GEM detectors was tested with different patterned anode planes (i.e., different signal readouts): a simple hexagonal readout structure and three structures with interconnected electrodes (XY square, XY rectangular, and UXV). It was found that under intense photon flux, all the readouts fail to account for a considerable amount of the incoming signals due to mostly photon position determination ambiguity and overlapped signals. Analysis of the signals that can be used to determine photon position and energy unambiguously showed that the UXV readout structure is more effective among the readouts with interconnected electrodes. Along with similar spatial resolution and accuracy, the UXV based layout could be considered as a quite promising base of the interconnected anode electrodes configuration, keeping in mind that the photon rate capability has to be improved for the final application.
Magnetoelectric memory effect of paramagnetic nonpolar phase in Co4Nb2O9
Authors: Xie Y. M. , Zang H. , Ceng W. D. , Wu H. Y. , Wang C. C.
Published: August 2018

A polarization memory effect of the paramagnetic nonpolar phase is observed in magnetoelectric antiferromagnet Co4Nb2O9, which has a magnetic field induced polarization in the antiferromagnetic phase. Following magnetoelectric poling in the polar phase, the nonpolar paramagnetic state retains a strong memory of polarization. When reentering the polar phase without applying the electric field, a polarization along the initial poling direction is recovered. If the applied magnetic field while staying in the paramagnetic phase is weakened, the memory effect is enhanced. With reversing this magnetic field, the polarization is also reversed when reentering the polar phase. The memory effect can be attributed to the ferroelectric seeds forming in the nonpolar phase due to short-range magnetic ordering as evidenced by magnetic entropy data.
On the Liouvillian solutions to the perturbation equations of the Schwarzschild black hole
Authors: Melas Evangelos
Published: August 2018

It is well known that the equations governing the evolution of scalar, electromagnetic, and gravitational perturbations of the background geometry of a Schwarzschild black hole can be reduced to a single master equation. We use Kovacic’s algorithm to obtain all Liouvillian solutions, i.e., essentially all solutions in terms of quadratures, of this master equation. We prove that the algebraically special Liouvillian solutions χ and χ∫dr *χ2, initially found by Chandrasekhar in the gravitational case, are the only Liouvillian solutions to the master equation. We show that the Liouvillian solution χ∫dr *χ2 is a product of elementary functions, one of them being a polynomial solution P to an associated confluent Heun equation. P admits a finite expansion both in terms of truncated confluent hypergeometric functions of the first kind, and also in terms of associated Laguerre polynomials. Remarkably both expansions entail not constant coefficients but appropriate function coefficients instead. We highlight the relation of these results with inspiring new developments. Our results set the stage for deriving similar results in other black hole geometries 4-dim and higher.
Smart electronic skin having gesture recognition function by LSTM neural network
Authors: Liu G. Y. , Kong D. Y. , Hu S. G. , Yu Q. , Liu Z. , Chen T. P. , Yin Y. , Hosaka Sumio , Liu Y.
Published: August 2018

Rapid growth of soft electronics has enabled various approaches for developing artificial skin. However, currently existing electronic skin is still facing some problems such as high fabrication complexity, high production cost, and smartness of recognizing the stimulus automatically. In this work, we report a simple, low-cost Polydimethylsiloxane (PDMS)-based smart electronic skin system, consisting of a sensor array and a data processing system. The sensor array can be easily mounted on the human body or robot hand as a result of excellent softness, stretchability, and bendability of PDMS. Signals from the sensor array are processed by a Long and Short Term Memory neural network algorithm in the data processing system. The trained data processing system can recognize four types of gestures at an accuracy of 85 ± 5%, even taking into account environmental variations including folding, curvature, tensile strength, temperature, and endurance cycles. This work proves that this type of skin can be endowed with intelligence with a proper neural network algorithm and fabricated at low cost and reduced complexity.
Non-monotonic thickness dependence of Curie temperature and ferroelectricity in two-dimensional SnTe film
Authors: Yang Chao , Liu Yanyu , Tang Gang , Wang Xueyun , Hong Jiawang
Published: August 2018

Recently, the observation of atomic thin film SnTe with a Curie temperature (Tc) higher than that of the bulk [Chang et al., Science 353, 274 (2016)] has boosted the research on two-dimensional (2D) ferroic materials tremendously. However, the origin of such a phenomenon is yet to be thoroughly investigated, which hinders the understanding and design of materials with ferroic orders at the 2D limit. By using the density functional theory, we investigated the structural and ferroelectrical properties of 2D SnTe to reveal the thickness dependence. The calculated results demonstrate that 2D SnTe automatically transforms into a periodical bilayer structure, resulting from the surface effect. Moreover, based on the double-well potential and atomic distortion analysis, we found that the Tc of 2D SnTe is higher than that of the bulk counterpart, and more surprisingly, Tc exhibits a non-monotonous dependence of thickness, featuring a pronounced atomic distortion and Curie temperature maximum at 8 atomic-layers (4 unit cells). In addition, this non-monotonous dependence is sensitive to the external strain and it can be easily tuned by the external compressive strain.
Dynamics of electron attachment and photodissociation in iodide-uracil-water clusters via time-resolved photoelectron imaging
Authors: Kunin Alice , Li Wei-Li , Neumark Daniel M.
Published: August 2018

The dynamics of low energy electron attachment to monohydrated uracil are investigated using time-resolved photoelectron imaging to excite and probe iodide-uracil-water (I−·U·H2O) clusters. Upon photoexcitation of I−·U·H2O at 4.38 eV, near the measured cluster vertical detachment energy of 4.40 eV ± 0.05 eV, formation of both the dipole bound (DB) anion and valence bound (VB) anion of I−·U·H2O is observed and characterized using a probe photon energy of 1.58 eV. The measured binding energies for both anions are larger than those of the non-hydrated iodide-uracil (I−·U) counterparts, indicating that the presence of water stabilizes the transient negative ions. The VB anion exhibits a somewhat delayed 400 fs rise when compared to I−·U, suggesting that partial conversion of the DB anion to form the VB anion at early times is promoted by the water molecule. At a higher probe photon energy, 3.14 eV, I− re-formation is measured to be the major photodissociation channel. This product exhibits a bi-exponential rise; it is likely that the fast component arises from DB anion decay by internal conversion to the anion ground state followed by dissociation to I−, and the slow component arises from internal conversion of the VB anion.
Local quantification of coordination number for perovskite-related oxides using atomic resolution EELS maps
Authors: Haruta Mitsutaka , Higuchi Hiroki , Nemoto Takashi , Kurata Hiroki
Published: August 2018

The establishment of a method to quantify oxygen in metal oxides with atomic resolution is required in materials science. However, it is, in principle, difficult to experimentally extract such information with atomic resolution using scanning transmission electron microscopy combined with electron energy-loss spectroscopy due to the physically limited spatial resolution caused by the delocalization of inelastic scattering electrons. In this study, an experimental value of the elemental ratio of oxygen/cation obtained from the center of a cation column along a pseudo-cubic [100] observation for perovskite-related materials was correlated with the oxygen coordination number for the cation, although it did not reflect the information with atomic resolution. As a result, there are two types of correlations attributed to the difference in the existence of oxygen in the illuminated atomic column and average oxygen-cation bond length around A and B sites. The application of plural point analysis based on the present approach would be able to overcome the physical spatial limit and identify the position of an oxygen defect with atomic resolution. This result would be readily applicable or practical for studying a local amount of oxygen around interface structures of thin films, dislocation sites, and others.
Note: A novel experimental setup for high-pressure abrasive liquid nitrogen jet
Authors: Zhang Shikun , Huang Zhongwei , Shi Huaizhong , Zhou Chunchun , Wu Xiaoguang , Huang Pengpeng
Published: August 2018

A high-pressure abrasive liquid nitrogen (L-N2) jet is considered as an efficient rock-breaking technology due to its unique low-temperature characteristic. In order to experimentally investigate the impact of an abrasive L-N2 jet on rock breakage, a new setup, which considers the low temperature and high expansibility of L-N2, is put forward in this note. The setup is composed of four units: the power system, nitrogen-gas pressurization system, particle mixing system, and impingement system. Both a pre-mixed abrasive L-N2 jet and a post-mixed abrasive L-N2 jet can be achieved by this equipment. Moreover, it can also be used to investigate the influences of injection parameters and particle parameters on rock breakage. A series of experiments have been carried out based on the setup. The results further promote the application of an abrasive L-N2 jet.
High-performance small- and wide-angle X-ray scattering (SAXS/WAXS) experiments on a multi-functional laboratory goniometer platform with easily exchangeable X-ray modules
Authors: Bolze Joerg , Kogan Vladimir , Beckers Detlef , Fransen Martijn
Published: August 2018

Small-angle X-ray scattering (SAXS) is a well-established, versatile technique for the analysis of nanoscale structures and dimensions, e.g., in liquid dispersions, thin solid objects or powder samples. When combined with wide-angle X-ray scattering (WAXS), complementary information about the atomic structure can be obtained. SAXS experiments traditionally require dedicated instruments to achieve the desired angular resolution, sensitivity, stability, and speed of measurement. Here we demonstrate how a multi-functional laboratory goniometer platform, as widely being used for powder X-ray diffraction and for a variety of related techniques, can be configured with pre-aligned X-ray modules that enable advanced SAXS/WAXS experiments, without compromising the exceptional versatility of the instrument. Line and point collimation setups, as well as quick and easy switching between them, are readily possible. Key components are a detachable, evacuated beam path and a high-resolution, low-noise hybrid pixel area detector, in combination with a hardware interface design that allows to configure the instrument with different X-ray modules without the need for re-alignment. Software for SAXS data reduction and analysis was developed. The good SAXS/WAXS performance and the derived analytical results were verified on various test samples, such as gold nanoparticles, colloidal silica, liposomes, dilute protein solutions, and solid polymer samples. It is believed that this novel approach to SAXS/WAXS instrumentation will help to make this powerful structure analysis technique more widely accessible and affordable for multi-user laboratories.
Isotopic analysis of deuterated water via single- and double-pulse laser-induced breakdown spectroscopy
Authors: Burger M. , Skrodzki P. J. , Finney L. A. , Hermann J. , Nees J. , Jovanovic I.
Published: August 2018

Spatial segregation of species presents one of the main challenges in quantitative spectroscopy of laser-produced plasmas, as it may lead to overestimation of the concentration of the heavier species. Analytical capabilities can also be affected by excessive Stark broadening at atmospheric pressure, hindering the ability to spectrally resolve closely spaced spectral lines, such as those belonging to isotopes of the same element. We present an experimental and modeling study of the segregation of species and spectral line broadening in D2O-H2O plasma produced by single- and double-pulse nanosecond laser ablation in air. The ability to resolve Balmer spectral lines of hydrogen and deuterium is investigated by considering the effects of plume segregation. Transient plasma properties which lead to improvements in spectral line separation are discussed. While the plume segregation is found to be negligible in air regardless of the ablation scheme used, we observe a significant improvement in the separation of isotopic spectral lines by employing the double-pulse excitation. This study may lead to increased reliability of optical emission spectroscopy in deuterium-rich plasma environments and suggests the potential for sensitive detection of tritium in air via laser-induced breakdown spectroscopy.
Enhancement of zonal flow damping due to resonant magnetic perturbations in the background of an equilibrium E × B sheared flow
Authors: Leconte M. , Singh R.
Published: August 2018

Using a parametric interaction formalism, we show that the equilibrium sheared rotation can enhance the zonal flow damping effect found in Leconte and Diamond [Phys. Plasmas 19, 055903 (2012)]. This additional damping contribution is proportional to (Ls/LV)2×δBr2/B2, where Ls/LV is the ratio of magnetic shear length to the scale-length of equilibrium E × B flow shear, and δBr/B is the amplitude of the external magnetic perturbation normalized to the background magnetic field.
Weight multiplicity formulas for bivariate representations of classical Lie algebras
Authors: Lauret Emilio A. , Rossi Bertone Fiorela
Published: August 2018

A bivariate representation of a complex simple Lie algebra is an irreducible representation whose highest weight is given by a combination of the first two fundamental weights. For a complex classical Lie algebra, we establish an expression for the weight multiplicities of bivariate representations.
Strong instability of standing waves for the fractional Choquard equation
Authors: Saanouni Tarek
Published: August 2018

Using variational methods and the potential well theory, strong instability of standing waves for a class of fractional Schrödinger-Choquard equations is established in the mass super-critical and energy sub-critical case.
Weakly nonlinear multi-mode Rayleigh-Taylor instability in two-dimensional spherical geometry
Authors: Zhang J. , Wang L. F. , Ye W. H. , Wu J. F. , Guo H. Y. , Ding Y. K. , Zhang W. Y. , He X. T.
Published: August 2018

A weakly nonlinear model is proposed for the multi-mode incompressible Rayleigh-Taylor instability in two-dimensional spherical geometry. The second-order solutions are derived, which can be applied to arbitrary small initial perturbations. The cosine-type and the Gaussian-type perturbations are discussed in detail. The growth of perturbations at the pole and that at the equator are compared, and the geometry effect is analyzed. It is found that the initial identical perturbation at the pole and the equator in the cross-sectional view will grow asymmetrically. In the linear regime, the perturbation amplitudes at the pole grow faster than those at the equator due to the different topologies. The geometry effect accelerates the ingoing motion and slows down the outgoing motion in the weakly nonlinear regime. This effect is stronger at the pole than that at the equator.
Transient interaction between a particle and an attached bubble with an application to cavitation in silt-laden flow
Authors: Li Shuai , Zhang A-Man , Wang Shiping , Han Rui
Published: August 2018

This study aims to elucidate the complex interaction between a suspended particle and an attached bubble, which is associated with cavitation in silt-laden flow. Systematic experiments are performed with high-speed photography, in which bubbles are generated by underwater electric discharge means. The bubble-particle interactions are found to be strongly dependent on two dimensionless parameters, i.e., the particle-bubble size ratio λL and the particle-liquid density ratio λρ. When λρ equals 2.61, the bubble split phenomenon is universally observed and the particle shooting effect (the particle acceleration during bubble expansion and after bubble-particle detachment) becomes more obvious as λL decreases. If λL < ∼0.34, the particle velocity keeps positive (away from the bubble), otherwise the particle velocity drops below zero (toward the bubble) during the bubble collapse phase. As λρ increases, the particle achieves a lower velocity but a higher impulse, and the bubble necking phenomenon is more pronounced. Our boundary integral simulations reproduce the experiments extremely well, including the particle dynamics, the bubble wrapping the particle, the bubble necking and detachment, and the mushroom-shaped bubble. After the bubble-particle detachment, the liquid around the detachment location is drawn inward and collides on the axis of symmetry, leading to the formation of a localized high pressure region between the bubble and the particle, which accelerates the particle for the second time even in the bubble collapse phase.
Self-biased vector magnetic sensor based on a Love-type surface acoustic wave resonator
Authors: Liu Xiangli , Tong Bei , Ou-Yang Jun , Yang Xiaofei , Chen Shi , Zhang Yue , Zhu Benpeng
Published: August 2018

Magnetic sensors based on the interaction between the delta-E effect and surface acoustic waves (SAWs) are promising devices due to their simple driving circuits. In this study, a magnetic sensor composed of a (Fe90Co10)78Si12B10 magnetic layer and Love-type SAW resonator was investigated. The resonance frequency sensitivities (RFS) of the sensor resulting from the delta-E effect are 76.06 Hz/μT and 364.28 Hz/μT in the L-direction (along the easy axis) and W-direction (along the hard axis), respectively. The maximum RFS achieved by this magnetic sensor is 663.98 Hz/μT along the hard axis, with a resonance frequency of 221.76 MHz. The shift of resonance frequency shows a good linearity along with the external magnetic field in the L-direction. The curves of frequency response demonstrate point symmetry rather than the expected axial symmetry in both directions, due to the existence of residual magnetization. Non-zero RFS at zero magnetic field also appears in this device, because of the non-zero change of the Young's modulus at zero magnetic field. The good linearity and high sensitivity mean that the investigated magnetic sensor can be applied for weak DC magnetic field detection.
Electron dynamics in twisted light modes of relativistic intensity
Authors: Baumann C. , Pukhov A.
Published: August 2018

The present work investigates the interaction of electrons with different circularly polarized twisted light pulses in the framework of relativistic particle-in-cell simulations in a fully three-dimensional geometry. It is found that the interaction is very sensitive to both the twisted light mode and the handedness of the laser. It will be shown that the twisted light pulse can be used to excite spatially structured electron beams. Depending on the chosen laser parameters, it becomes possible to drive a train of azimuthally symmetric electron bunches or to excite a discrete number of helical electron beams. The emerging electron patterns are characterized by full width at half maximum durations of the order of a few hundred attoseconds. In addition, an efficient transfer of angular momentum from the twisted light field to the particles is reported. Potentially, the proposed scheme might have interesting applications, for instance, as a diagnostic tool for ultra-fast physical systems.
Effect of peak stress and tensile strain-rate on spall in tantalum
Authors: Jones D. R. , Fensin S. J. , Martinez D. T. , Trujillo C. P. , Gray G. T.
Published: August 2018

Materials subjected to dynamic environments experience a complex and wide range of stress, strain, and strain-rate conditions. To have confidence in material models, an accurate, predictive capability is required. In this study, we present a series of flyer-plate impact tests on well characterized, high purity tantalum. The shock-waves generated at impact release from the free-surfaces, reflect, and interact to produce incipient spall fracture. By varying the flyer-plate material and impact velocity, both the peak stress and the strain-rate in the samples were controlled independently. Velocimetry was used on the rear free-surface of the samples to measure the shock-response and the spall strength. While this measurement provided the same spall strength for all cases, at approximately 5.1 GPa, when the samples were sectioned during post-mortem, the quantity and distribution of internal damage was markedly different. For the high-strain rate cases, voids remained small and isolated, whereas in the lower strain-rate experiments, the spall damage was far more localized, with a well-defined continuous spall plane. With the use of hydrocode simulations, this was discovered to result from how the different release rates affect the interaction volume inside the sample. These results highlight the importance of careful sample recovery, and the risks of relying solely on free-surface velocity measurements.
Communication: A mean field platform for excited state quantum chemistry
Authors: Shea Jacqueline A. R. , Neuscamman Eric
Published: August 2018

We present a mean field theory for excited states that is broadly analogous to ground state Hartree-Fock theory. Like Hartree-Fock, our approach is deterministic, state-specific, applies a variational principle to a minimally correlated ansatz, produces energy stationary points, relaxes the orbital basis, has a Fock-build cost-scaling, and can serve as the foundation for correlation methods such as perturbation theory and coupled cluster theory. To emphasize this last point, we pair our mean field approach with an excited state analog of second order Møller-Plesset theory and demonstrate that in water, formaldehyde, neon, and stretched lithium fluoride, the resulting accuracy far exceeds that of configuration interaction singles and rivals that of equation of motion coupled cluster.
Experimental observation of size-dependent behavior in surface energy of gold nanoparticles through atomic force microscope
Authors: Liu Jiangwei , Papadakis Raffaello , Li Hu
Published: August 2018

Surface energy plays a key role in the physicochemical interactions of material surfaces, and it is closely related to the unique properties and numerous surface functionalization possibilities of gold nanoparticles. Herein, we have reported an atomic force microscopy based technique to measure the surface energies of different materials in the peakforce quantitative nanomechanical mapping mode. Our study on gold nanoparticles focuses on the particles with diameters ranging from 2 to 14 nm. The experimental results indicate a clear size-dependent behavior in the surface energy of gold nanoparticles when the size is smaller than 5 nm, and the smallest gold nanoparticle displays a threefold higher surface energy compared to bulk gold. Therefore, our experimental results provide essential evidence that can lead to a better understanding of the size-property relationships allowing for process design in gold nanoparticles.
Evidence for a recent decline in the distribution and abundance of the New Holland mouse (Pseudomys novaehollandiae) in Tasmania, Australia
Authors: Lazenby Billie T. , Bell Phil , Driessen Michael M. , Pemberton David , Dickman Christopher R.
Published: August 2018

The New Holland mouse (Pseudomys novaehollandiae) was recognised to be at threat of extinction at an International, National, and Tasmanian State level in 2008, 2010, and 1995, respectively. The species inhabits the floristically diverse dry heathlands and associated vegetation communities that typically arise from mosaic burns. In this regard the New Holland mouse could be considered a flagship species for healthy heathlands. We present 18 years of search and capture records collected since 1998 from Tasmania to show that there has been a contraction over the last nine years from 16 to 2 in the number of sites from which the species has been detected, and more than a 99% reduction in capture-per-unit-effort. These results raise concern as to the viability of the species in Tasmania. Strength of inference regarding the magnitude and causes of decline in distribution and abundance would be improved by regular and systematic monitoring. The considerable overlap between the potential causes of the New Holland mouse’s decline in Tasmania and regional declines in mammal assemblages nationally, suggest that recovery efforts for the New Holland mouse could have positive outcomes for all species inhabiting lowland dry heathlands in Australia.
Near-term embryos and gravid females of Lusitanian cownose ray (Rhinoptera marginata) in Mersin Bay, eastern Mediterranean Sea
Authors: Tıraşın E. Mümtaz , Başusta Nuri
Published: August 2018

Batoid chondrichthyans are vulnerable to commercial fisheries even though they are often not targeted. A greater understanding of their reproductive biology is important to facilitate their conservation. In February 2013, 89 female and 40 male Lusitanian cownose ray (Rhinoptera marginata) specimens were accidentally caught in Mersin Bay in the eastern Mediterranean Sea. Thirty-six fish were gravid, each bearing one embryo. Of the remaining females, 39 were sexually mature but not gravid and 14 were immature. There were 28 mature and 12 immature males. The average disc width (DW) of both mature females (80.2cm) and males (74.2cm) was significantly higher than that of immature females (60.7cm) and males (60.3cm). For all rays, DW and total weight (TW) were in the range 55.7–98.2cm and 1802–13600g. The DW and TW measured for all 16 female and 20 male embryos were in the range 15.6–29.2cm and 57–281g. Such a large single haul sample, including many gravid specimens and mature males, indicates a schooling formation at capture. The location in Mersin Bay near the estuaries of the Tarsus and Seyhan rivers, and its relative closeness to the sampling location of a previously reported neonate, suggests that this region may be a nursery area for Lusitanian cownose rays in the eastern Mediterranean.