bluuebunny/crossref_metadata_2025 huggingface dataset:
Blood Pressure Response to Muscle Metaboreflex Activation is Impaired in Men Living with HIV
Authors: Gama Gabriel , Farinatti Paulo , Crisafulli Antonio , Borges Juliana
Published: October 2020

We investigated the muscle metaboreflex contribution to blood pressure response during dynamic handgrip exercise in men living with HIV (MLHIV) vs. without HIV (Controls). Pressor and heart rate responses were evaluated during metaboreflex activation through post-exercise muscle ischemia (PEMI) method and control exercise session (CER) in 17 MLHIV and 21 Controls. Protocols were performed randomly on the same day, being both sessions composed of 12 min, as follows: a) 3 min at rest, b) 3 min of dynamic handgrip exercise at 30% of maximal voluntary contraction, c) 3 min of recovery post-exercise with vascular occlusion (occlusion only in PEMI), and d) 3 min of recovery post-exercise without vascular occlusion. To assess metaboreflex response, differences between PEMI and CER in recovery post-exercise were calculated for blood pressure and heart rate. Systolic and mean blood pressure (P<0.01) were superior in the last 2 min of recovery with vascular occlusion at PEMI in relation to CER for both groups. No difference was found between groups for blood pressure and heart rate (P>0.05). However, metaboreflex response for systolic blood pressure was lower in MLHIV vs. Controls (4.05±4.63 vs. 7.61±3.99 mmHg; P=0.01). In conclusion, pressor response during metaboreceptor stimulation was attenuated in men living with HIV, which may suggest loss of muscle metaboreflex sensibility.
Convergent Synthesis of Immune Inhibitor IMMH002
Authors: Xiao Qiong , Chen Si , Shi Zeyu , Yin Dali
Published: October 2020

A convergent synthesis of IMMH002 in 36% overall yield starting from bromobenzene is described with a key Suzuki–Miyaura cross-coupling reaction used to provide a crucial intermediate. The route does not require column chromatography and solves the most intractable quality problem caused by a homologue by-product in the original linear synthesis. Furthermore, reducing the use of Lewis acid mediated reactions improves the environmental impact of the synthesis and reduces overall waste. The new route described herein is more efficient, convenient, reliable, and economically more viable when compared to the previously reported linear route.
Therapeutic Hypothermia in Transport Permits Earlier Treatment Regardless of Transfer Distance
Authors: Leon Rachel L. , Krause Katherine E. , Sides Rebecca S. , Koch Mary Beth , Trautman Michael S. , Mietzsch Ulrike
Published: October 2020

Objective Therapeutic hypothermia (TH) is currently the only effective therapy available to improve outcomes in neonates with hypoxic-ischemic encephalopathy (HIE) and has maximal effect when initiated within 6 hours of birth. Neonates affected by HIE are commonly born outside of cooling centers and transport is a barrier to timely initiation. In this study, we sought to determine if the initiation of servo-controlled TH in transport allowed neonates to reach target temperature earlier, without a significant delay in the transfer process, for both local and long-distance transport.

Study Design In this single-center cohort study of neonates referred to a level IV neonatal intensive care unit for TH, we determined the chronologic age at which target temperature was reached for those cooled in transport. Short-term outcome measures were assessed, including survival, incidence of electrographic seizures, discharge feeding method, and length of hospitalization.

Results In a study population of 85 neonates, those receiving TH during transport (n = 23), achieved target temperature (33–34°C) 77 minutes sooner (230 ± 71 vs. 307 ± 79 minutes of life (MOL); p < 0.001). Locally transported neonates (<15 miles) achieved target temperature 69 minutes earlier (215 ± 48 vs. 284 ± 74 MOL; p < 0.01). TH during long-distance transports allowed neonates to reach target temperature 81 minutes sooner (213 ± 85 vs. 294 ± 79 MOL; p < 0.01). Infants who were cooled in transport discharged 4 days earlier (13.7 ± 8 vs. 17.8 ± 13 days; p = 0.18) and showed a significantly higher rate of oral feeding at discharge (95 vs. 71%; p = 0.03).

Conclusion For those starting TH in transport, time to target temperature was decreased. In our cohort, cooling in transport was associated with improved short-term outcomes, although additional studies are needed to correlate these findings with long-term outcomes.

Key Points
Inflammatory Proteins in the Amniotic Fluid, Plasma, and Cervicovaginal Fluid for the Prediction of Intra-Amniotic Infection/Inflammation and Imminent Preterm Birth in Preterm Labor
Authors: Kim Su A. , Park Kyo H. , Lee Seung M. , Kim Yu M. , Hong Subeen
Published: October 2020

Objective This study was aimed to develop models using multiple cytokine/chemokine levels in cervicovaginal fluid (CVF) and plasma and widely used noninvasive parameters that have better accuracy for predicting intra-amniotic infection and/or inflammation (IAI) and imminent spontaneous preterm delivery (SPTD, ≤48 hours) in women with preterm labor (PTL).

Study Design This was a retrospective cohort study of 95 singleton pregnant women with PTL (23–34 weeks) who underwent amniocentesis. Both CVF and plasma samples were obtained at the time of amniocentesis, and serum C-reactive protein (CRP) levels were measured. The amniotic fluid (AF), CVF, and plasma samples were assayed for interleukin (IL)-6, IL-8, IL-10, monocyte chemotactic protein-1 (MCP-1), and macrophage inflammatory protein-1β (MIP-1β) levels using a multiplex immunoassay kit.

Results The levels of most cytokines/chemokines measured in the AF and CVF were significantly higher in the women with than in those without IAI and imminent SPTD, whereas only high-plasma IL-10 level showed a significant association with imminent SPTD. In predicting IAI, proteins in AF had significantly higher areas under the curves (AUCs) than those in CVF and plasma. However, for predicting imminent SPTD, no significant differences in the AUCs of the outcome-associated proteins were observed among the measurements in AF, CVF, and maternal plasma. By using stepwise regression analyses, noninvasive models (using protein levels in CVF and baseline clinical parameters) were developed for the prediction of IAI and imminent SPTD. The AUC of these noninvasive models were similar to those of the invasive models (using AF protein levels and baseline clinical parameters).

Conclusion Noninvasive models based on CVF cytokine/chemokine levels and widely used noninvasive parameters (especially CRP) act as good indicators for predicting the risk of IAI and imminent SPTD in women with PTL. Evaluation of cytokine/chemokine levels in plasma samples did not add valuable information regarding the two outcome measures in the PTL setting.

Key Points
Perceptions on the use of heritage to teach history in Secondary Education teachers in training
Authors: Felices-De la Fuente María del Mar , Chaparro-Sainz Álvaro , Rodríguez-Pérez Raimundo A.
Published: October 2020

Recently, heritage education has undergone significant development, consolidating itself as a scientific discipline in the last two decades. In this sense, it is a key element for teaching history and training social and civic skills. However, in Spanish school contexts the presence of heritage in connection with historical education is currently scarce and anecdotal. Transforming this situation necessarily involves knowing the opinion of future Secondary Education teachers about the possibilities that they grant to heritage to develop historical thinking. Only in this way it is possible to detect the needs that future teachers show to intervene in them and improve training processes at the university. Therefore, this paper analyses the perceptions of heritage in future secondary education teachers at three Spanish universities (Malaga, Almeria, and Murcia), with a total sample of 112 participants (n = 112). It combines a quantitative study using a Likert scale questionnaire, with a qualitative one, by means of a series of open questions about the participants’ perceptions of teaching methodologies and didactic resources. This allows some striking conclusions to be drawn, as well as certain contradictions that allude to the gap between the hegemonic forms of teaching that they have known as students, and those that they would like to develop when they enter teaching. These trainee teachers attach great importance to the use of tangible and intangible heritage to teach history and make it an attractive subject. They also show great interest in local history, museums, and new technologies. All of this is rarely used in the teaching of history in Spain at the Secondary Education stage, and therefore is a deficiency that future teachers recognize needs addressing. The teaching of heritage should promote a greater role for students, making them builders of their own learning. This means acquiring not only concepts, but above all skills and civic values, based on the study of heritage.
The renormalized Bogoliubov–Fröhlich Hamiltonian
Authors: Lampart Jonas
Published: October 2020

The Bogoliubov–Fröhlich Hamiltonian models the interaction of an impurity with the excitations of a Bose–Einstein condensate. It has been observed that the dependence of the ground state energy on the ultraviolet (UV) cutoff differs significantly from what would be expected from similar well-known models. We give a detailed explanation of this UV behavior and provide an explicit representation of the renormalized Hamiltonian.
A coupled model of stress, creep, and diffusion in the film/substrate system
Authors: Xie Feng , Li Huimin , Zhang Weixu , Ma Qingzhong
Published: October 2020

A film/substrate system is a common structural form. In its fabrication and/or operation process, diffusion is a basic and key procedure. However, there still exist unclear points in the diffusion process, i.e., the effects of stress, creep, and interface properties. To clarify these unclear points, in this paper, a coupled diffusion model including stress, creep, and interface property is established. The obtained results indicate that compressive stress retards the diffusion of guest atoms. Meanwhile, creep reduces the retardation of diffusion through releasing the induced compressive stress, and then the concentration of the guest atoms can reach the prescribed value, which overcomes the much lower concentration predicted by the previous models without creep. In addition, interfacial diffusivity affects diffusion and the maximum stress in the film.
Resolving the discrepancy between theoretical and experimental polarization of hyperpolarized 129Xe using numerical simulations and in situ optical spectroscopy
Authors: Kelley Michele , Burant Alex , Branca Rosa Tamara
Published: October 2020

For emerging biomedical applications of hyperpolarized xenon, the ability to obtain reliably high nuclear spin polarization levels is paramount. Yet, experimental nuclear spin polarization levels of xenon are highly variable and, more than often than not, well below what theory predicts. Despite rigorous and well-studied theoretical models for hyperpolarization and continuous-flow spin-exchange optical pumping (SEOP), there remains a substantial discrepancy between the theoretical and experimental polarization of 129Xe; inexplicably, seemingly similar experimental parameters can yield very different polarization values. In this paper, the validity of the assumptions typically made about the thermodynamic state of the Rb vapor inside the optical pumping cell and the gas dynamics are investigated through finite element analysis simulations of realistic optical pumping cell models, while in situ optical and nuclear magnetic resonance spectroscopy measurements are used to validate the results of the simulations. Our results show that shorter xenon gas residence times and lower Rb vapor densities than those predicted by empirical saturated vapor pressure curves, along with incorrect SEOP parameters, are the primary cause of the discrepancy between theoretical and experimental polarization values reported in the literature.
Magnetic reconnection in a charged, electron-dominant current sheet
Authors: Lu San , Angelopoulos V. , Artemyev A. V. , Jia Yingdong , Chen Qianfan , Liu Jiang , Runov A.
Published: October 2020

Magnetic reconnection occurs in current sheets in various plasma environments, and the reconnection process is controlled by the current sheet characteristics. Most theoretical and simulation studies of magnetic reconnection are based on the neutral current sheet model in which the current is primarily carried by ions. Current sheets in natural plasmas (e.g., in Earth's magnetotail), however, are usually charged with nonzero electric field, and usually the current therein is primarily carried by electrons. Here using particle-in-cell simulations, we study magnetic reconnection in a charged, electron-dominant current sheet and show that reconnection in this current sheet is weaker, has a larger diffusion region, and occurs more easily than reconnection in the neutral, ion-dominant current sheet. Two other current sheet characteristics, the background density and background temperature, also affect the reconnection process significantly.
Effect of krypton admixture in deuterium on neutron yield in a megaampere dense plasma focus
Authors: Hahn E. N. , Housley D. , Narkis J. , Conti F. , Lowe D. R. , Beg F. N.
Published: October 2020

Experiments on a MA-class Dense Plasma Focus (DPF) device have been carried out to investigate changes in neutron production by adding moderate amounts of krypton to a deuterium fill gas. The neutron yield from Z-pinch devices, including DPFs, conventionally scales as the peak current to the fourth power. However, a dramatic drop-off from ∼I4 scaling occurs above 3 MA, which recent modeling [D. T. Offermann et al., Phys. Rev. Lett. 116, 195001 (2016)] attributed to the transition in the predominant neutron production mechanism from beam-target fusion to thermonuclear fusion. Previously, the addition of Kr (and other high-Z) dopants has been shown to enhance beam-target fusion yields at currents below 300 kA, with optimal concentrations at 1%–2% Kr, whereas here we show that the optimal concentration of Kr at the MA level is near 0.1% by volume—elucidating a trend in the optimal Kr doping concentration as a function of the device scale. The neutron time-of-flight data reveal that Kr doping creates shorter and more intense neutron bursts, likely due a tighter but unstable pinch, highlighting a key trade-off for Kr doping.
Diversity of transverse flexoelectricity in non-poled polyvinylidene fluoride
Authors: Zhang Shuwen , Liu Kaiyuan , Wu Tonghui , Ji Hui , Xu Minglong , Shen Shengping
Published: October 2020

As a promising electromechanical effect in dielectric materials, flexoelectricity describes the linear relation between a strain gradient and its induced electric polarization. Flexoelectricity in polymeric materials is separated from that of crystal dielectrics in both the mechanism and value due to their complicated structures. Independent works reported flexoelectric coefficients of one material as different values, even spanning magnitudes. Curiosity then comes on the exact flexoelectric coefficients of polymeric dielectrics. In this work, diversity of transverse flexoelectricity in non-poled bulk polyvinylidene fluoride on three geometric dimensionalities is researched and discussed. An obvious diversity of transverse flexoelectricity is revealed by investigating two transverse flexoelectric coefficient components, which may be induced by pre-existed charges of materials. This work indicates that the flexoelectric response exists in a range in one polymeric material. This result also expands a possibility of applications with flexoelectricity in polymeric materials and additionally highlights the importance of the mechanism in low-symmetric dielectric solid materials.
Normal modes, rotational inertia, and thermal fluctuations of trapped ion crystals
Authors: Dubin Daniel H. E.
Published: October 2020

The normal modes of a trapped ion crystal are derived using an approach based on the Hermitian properties of the system's dynamical matrix. This method is equivalent to the standard Bogoliubov method, but for classical systems, it is arguably simpler and more general in that canonical coordinates are not necessary. The theory is developed for stable, unstable, and neutrally stable systems. The method is then applied to ion crystals in a Penning trap. Reduced eigenvalue problems for the case of large applied magnetic fields are developed, for which the spectrum breaks into E × B drift modes, axial modes, and cyclotron modes. Thermal fluctuation levels in these modes are analyzed and shown to be consistent with the Bohr–van-Leeuwen theorem, provided that neutrally stable modes associated with crystal rotations are included in the analysis. An expression for the rotational inertia of the crystal is derived, and a magnetic contribution to this inertia, which dominates in large magnetic fields, is described. An unusual limit is discovered for the special case of spherically symmetric confinement, in which the rotational inertia does not exist and changes in angular momentum leave the rotation frequency unaffected.
Signatures of exciton dynamics and interaction in coherently and fluorescence-detected four- and six-wave-mixing two-dimensional electronic spectroscopy
Authors: Malý Pavel , Mueller Stefan , Lüttig Julian , Lambert Christoph , Brixner Tobias
Published: October 2020

Two-dimensional electronic spectroscopy (2DES) can be realized in increasing nonlinear orders of interaction with the electric field, bringing new information about single- and multi-particle properties and dynamics. Furthermore, signals can be detected both coherently (C-2DES) and by fluorescence (F-2DES), with fundamental and practical differences. We directly compare the simultaneous measurements of four- and six-wave mixing C-2DES and F-2DES on an excitonic heterodimer of squaraine molecules. Spectral features are described in increasing orders of nonlinearity by an explicit excitonic model. We demonstrate that the four-wave-mixing spectra are sensitive to one-exciton energies, their delocalization and dynamics, while the six-wave-mixing spectra include information on bi-exciton and higher excited states including the state energies, electronic coupling, and exciton–exciton annihilation. We focus on the possibility to extract the dynamics arising from exciton–exciton interaction directly from the six-wave-mixing spectra. To this end, in analogy to previously demonstrated fifth-order coherently detected exciton–exciton-interaction 2DES (EEI2D spectroscopy), we introduce a sixth-order fluorescence-detected EEI2D spectroscopy variant.
Raman scattering in heavily donor doped
β
-Ga2O3
Authors: Fiedler A. , Ramsteiner M. , Galazka Z. , Irmscher K.
Published: October 2020

β-Ga2O3 crystals doped with the donor impurities Si or Sn are investigated by Raman spectroscopy. In addition to the well-known intrinsic Raman allowed phonon modes, we discover several spectral features when the doping concentration exceeds the Mott criterion for the metal-insulator transition (∼ 3 × 1018 cm−3). The most prominent extra Raman peak at 255 cm−1 is an asymmetrically broadened one. It is due to single-particle, electronic excitations involving the impurity band formed by effective-mass-like (hydrogenic) shallow donors. A similar type of excitation is attributed to a Raman line at 675 cm−1 that appears below room temperature in Si doped samples and might be due to a non-hydrogenic donor. Furthermore, we observe four longitudinal phonon-plasmon coupled modes at 215 cm−1, 280 cm−1, 400 cm−1, and 560 cm−1 associated with infrared active phonon modes. They arise from inelastic light scattering via charge-density fluctuations.
Planar, strong magnetic field source for a chip ion trap
Authors: Pinder Jonathan , Lacy John H. , Willetts Ryan , Cridland Mathad April , Uribe Alberto , Verdú José
Published: October 2020

We present a planar, scalable magnetic field source, originally conceived for a chip ion trap. It consists of two symmetric sections, each with several independent currents arranged in coplanar, concentric rectangular loops. The currents allow for tuning the strength of the field and its lowest-order derivatives at one discretional position along the source’s vertical symmetry axis, a few mm above its surface. We describe the construction and calibration of the device and the cryogenic setup. The two most important current configurations for a Penning ion trap, the homogeneous field and the magnetic bottle, are investigated experimentally. Homogeneous fields around 0.5 T are routinely reached. We discuss the maximum attainable field, and we briefly describe ongoing further developments aiming at homogeneous fields well above 1 T.
Study of regular reflection shock waves using a mesoscopic kinetic approach: Curvature pattern and effects of viscosity
Authors: Qiu Ruofan , Bao Yue , Zhou Tao , Che Huanhuan , Chen Rongqian , You Yancheng
Published: October 2020

The physical characteristics inside shock waves with nonequilibrium molecular motion are difficult to describe using conventional macroscopic methods. In this paper, nonequilibrium hydrodynamic and thermodynamic effects caused by the strong nonequilibrium molecular velocity distribution at a shock wave are studied using a mesoscopic kinetic approach. This approach is based on a lattice Boltzmann method and a kinetic nonequilibrium method. The former adopts a compressible double-distribution-function model with separated density and total energy distribution functions. The latter represents the nonequilibrium effects through nonequilibrium kinetic moments based on the nonequilibrium molecular velocity distribution. The nonequilibrium effects in the steady state and the process of the formation of a regular reflection shock wave are presented. Nonequilibrium effects inside the shock wave are further investigated. First, the curvature pattern during the formation of a regular reflection shock wave is addressed. The curvature characteristic leads to distinct features of nonequilibrium effects compared with the linear pattern. A vector-based approach for visualizing nonequilibrium effects is proposed to study the curvature pattern. Second, the influence of viscosity on nonequilibrium effects, which is related to the average collision time among molecules at the shock wave, is explored. The results obtained in this paper provide mesoscopic physical insight into the flow mechanisms occurring in shock waves.
Acoustic impedance regulation of Helmholtz resonators for perfect sound absorption via roughened embedded necks
Authors: Duan Mingyu , Yu Chenlei , Xu Zhimin , Xin Fengxian , Lu Tian Jian
Published: October 2020

Acoustic impedance regulation of a neck embedded Helmholtz resonator is realized by introducing surface roughness to the neck so as to convert the initially non-perfect sound absorber to a perfect sound absorber. The proposed roughened-neck embedded Helmholtz resonator (R-NEHR) achieves perfect sound absorption (α>0.999) at 158 Hz across a deep subwavelength thickness of λ/42. Theoretical predictions of the R-NEHR's performance are validated against experimental measurements. Physically, surface roughness triggers the periodic concentration effect of fluid vibration in the neck, thereby improving its acoustic mass and acoustic resistance and altering the resonant damping state of the absorber. As a result, the absorption peak position of the R-NEHR shifts by 16.0% to lower frequency, together with a peak value increase of 19.6%. This work provides an approach for perfect sound absorber design and impedance regulation of acoustic metamaterials.
Dielectrophoretic trapping and impedance detection of Escherichia coli, Vibrio cholera, and Enterococci bacteria
Authors: Kong Tian Fook , Shen Xinhui , Marcos  , Yang Chun , Ibrahim Imran Halimi
Published: October 2020

In this work, a dielectrophoretic impedance measurement (DEPIM) lab-on-chip device for bacteria trapping and detection of Escherichia coli, Vibrio cholerae, and Enterococcus is presented. Through the integration of SU-8 negative photoresist as a microchannel and the precise alignment of the SU-8 microchannel with the on-chip gold interdigitated microelectrodes, bacteria trapping efficiencies of up to 97.4%, 97.7%, and 37.7% were achieved for E. coli, V. cholerae, and Enterococcus, respectively. The DEPIM device enables a high detection sensitivity, which requires only a total number of 69 ± 33 E. coli cells, 9 ± 2 Vibrio cholera cells, and 36 ± 13 Enterococcus cells to observe a discernible change in system impedance for detection. Nonetheless, the corrected limit of detection for Enterococcus is 95 ± 34 after taking into consideration the lower trapping efficiency. In addition, a theoretical model is developed to allow for the direct estimation of the number of bacteria through a linear relationship with the change in the reciprocal of the overall system absolute impedance.
TD-DFTB study of optical properties of silver nanoparticle homodimers and heterodimers
Authors: Liu Zhen , Alkan Fahri , Aikens Christine M.
Published: October 2020

The absorption spectra for face-centered cubic nanoparticle dimers at various interparticle distances are investigated using time-dependent density functional tight binding. Both homodimers and heterodimers are investigated in this work. By studying nanoparticles at various interparticle distances and analyzing their vertical excitations, we found that as the interparticle distance decreases, a red shift arises from contributions of the transition dipole moment that are aligned along the z-axis with nondegenerate features; blue shifts occur for peaks that originate from transition dipole moment components in the x and y directions with double degeneracy. When the nanoparticles are similar in size, the features in the absorption spectra become more sensitive to the interparticle distances. The best-fit curves from vertical excitation energy in the form of AR−b for ΔEredshift/ΔEblueshift vs R are determined. In this way, we determined trends for absorption peak shifts and how these depend on the interparticle distance.
Detection of narrow lines in the inhomogeneously broadened line of P1 centers in diamond by double modulation EPR spectroscopy
Authors: Rakvin B. , Carić D. , Kveder M.
Published: October 2020

The study of double modulation continuous wave (CW) electron spin resonance (DM-EPR) is reported to detect narrow “spin-packet”-like lines within an inhomogeneous CW-EPR line of low concentration P1 (Ns0) centers ([Ns0] < 1 ppm) in diamond. These narrow lines appear as peaks at multiples of modulation frequency in the double modulation spectrum. It is shown that the respective line shape can be fitted assuming two Lorentzian line shapes. The linewidth of the narrower Lorentzian is comparable with the linewidth of the Lorentzian obtained from the T2 relaxation time δ1=1/πT2 estimated from the Hahn echo pulsed-EPR experiment. The broader component δ2 correlates with the T2* relaxation time obtained from the free induction decay measurement of the inhomogeneous spectral line shape of the P1 center. The ratio δ2/δ1∼18 derived from DM-EPR measurements approaches within the experimental error the value T2/T2*∼16 derived from pulsed-EPR. Sensitivity to the small shift of the magnetic field (∼0.6 μT) was shown to be detectable from the broadening behavior of the δ2 component. The results promote DM-EPR as a method complementary to pulsed-EPR for studying coherence times of low density paramagnetic centers in a diamond lattice like nitrogen-vacancy (NV−) center, since it exhibits similar properties to the here investigated P1 center in terms of long relaxation time at a monitored low concentration.
Theory and implementation of a novel stochastic approach to coupled cluster
Authors: Scott Charles J. C. , Di Remigio Roberto , Crawford T. Daniel , Thom Alex J. W.
Published: October 2020

We present a detailed discussion of our novel diagrammatic coupled cluster Monte Carlo (diagCCMC) [Scott et al. J. Phys. Chem. Lett. 10, 925 (2019)]. The diagCCMC algorithm performs an imaginary-time propagation of the similarity-transformed coupled cluster Schrödinger equation. Imaginary-time updates are computed by the stochastic sampling of the coupled cluster vector function: each term is evaluated as a randomly realized diagram in the connected expansion of the similarity-transformed Hamiltonian. We highlight similarities and differences between deterministic and stochastic linked coupled cluster theory when the latter is re-expressed as a sampling of the diagrammatic expansion and discuss details of our implementation that allow for a walker-less realization of the stochastic sampling. Finally, we demonstrate that in the presence of locality, our algorithm can obtain a fixed errorbar per electron while only requiring an asymptotic computational effort that scales quartically with system size, independent of the truncation level in coupled cluster theory. The algorithm only requires an asymptotic memory cost scaling linearly, as demonstrated previously. These scaling reductions require no ad hoc modifications to the approach.
Magnetic order in 3D topological insulators—Wishful thinking or gateway to emergent quantum effects?
Authors: Figueroa A. I. , Hesjedal T. , Steinke N.-J.
Published: October 2020

Three-dimensional topological insulators (TIs) are a perfectly tuned quantum-mechanical machinery in which counterpropagating and oppositely spin-polarized conduction channels balance each other on the surface of the material. This topological surface state crosses the bandgap of the TI and lives at the interface between the topological and a trivial material, such as vacuum. Despite its balanced perfection, it is rather useless for any practical applications. Instead, it takes the breaking of time-reversal symmetry (TRS) and the appearance of an exchange gap to unlock hidden quantum states. The quantum anomalous Hall effect, which has first been observed in Cr-doped (Sb,Bi)2Te3, is an example of such a state in which two edge channels are formed at zero field, crossing the magnetic exchange gap. The breaking of TRS can be achieved by magnetic doping of the TI with transition metal or rare earth ions, modulation doping to keep the electronically active channel impurity free, or proximity coupling to a magnetically ordered layer or substrate in heterostructures or superlattices. We review the challenges these approaches are facing in the famous 3D TI (Sb,Bi)2(Se,Te)3 family and try to answer the question whether these materials can live up to the hype surrounding them.
Beyond Graphene: Low-Symmetry and Anisotropic 2D Materials
Authors: Barraza-Lopez Salvador , Xia Fengnian , Zhu Wenjuan , Wang Han
Published: October 2020

Low-symmetry 2D materials—such as ReS2 and ReSe2 monolayers, black phosphorus monolayers, group-IV monochalcogenide monolayers, borophene, among others—have more complex atomistic structures than the honeycomb lattices of graphene, hexagonal boron nitride, and transition metal dichalcogenides. The reduced symmetries of these emerging materials give rise to inhomogeneous electron, optical, valley, and spin responses, as well as entirely new properties such as ferroelasticity, ferroelectricity, magnetism, spin-wave phenomena, large nonlinear optical properties, photogalvanic effects, and superconductivity. Novel electronic topological properties, nonlinear elastic properties, and structural phase transformations can also take place due to low symmetry. The “Beyond Graphene: Low-Symmetry and Anisotropic 2D Materials” Special Topic was assembled to highlight recent experimental and theoretical research on these emerging materials.
The DNA damage response links human squamous proliferation with differentiation
Authors: Molinuevo Rut , Freije Ana , Contreras Lizbeth , Sanz Juan R. , Gandarillas Alberto
Published: October 2020

How rapid cell multiplication leads to cell differentiation in developing tissues is still enigmatic. This question is central to morphogenesis, cell number control, and homeostasis. Self-renewal epidermoid epithelia are continuously exposed to mutagens and are the most common target of cancer. Unknown mechanisms commit rapidly proliferating cells to post-mitotic terminal differentiation. We have over-activated or inhibited the endogenous DNA damage response (DDR) pathways by combinations of activating TopBP1 protein, specific shRNAs, or chemical inhibitors for ATR, ATM, and/or DNA-PK. The results dissect and demonstrate that these signals control keratinocyte differentiation in proliferating cells independently of actual DNA damage. The DDR limits keratinocyte multiplication upon hyperproliferative stimuli. Moreover, knocking down H2AX, a common target of the DDR pathways, inhibits the epidermoid phenotype. The results altogether show that the DDR is required to maintain the balance proliferation differentiation and suggest that is part of the squamous program. We propose a homeostatic model where genetic damage is automatically and continuously cleansed by cell-autonomous mechanisms.
Covariant Noether charges for type IIB and 11-dimensional supergravities
Authors: Dias Óscar J C , Hartnett Gavin S , Santos Jorge E
Published: October 2020

The covariant Noether charge formalism (also known as the covariant phase method) of Wald and collaborators, including its cohomological extension, is a manifestly covariant Hamiltonian formalism that, in principle, allows one to define and compute the energy, angular momenta, and chemical potentials of generic solutions of gravitational theories. However, it has been observed that for some supergravity solutions the variation of the Noether charge is not (at least manifestably) integrable, and as a result it is unclear whether there are well-defined thermodynamic charges for these solutions. In this work, we derive an expression for the variation of the covariant Noether charges for any solution of type IIB 10-dimensional supergravity or 11-dimensional supergravity. Although this Noether quantity is not integrable in general, we show that for asymptotically scale-invariant solutions, it is. In particular, the asymptotic scale-invariance allows one to define an energy density and conjugate chemical potentials which obey a first law of thermodynamics and a Smarr relation. These two thermodynamic relations can then be shown to imply that the variation of the Noether charge is integrable, and accordingly the energy and other thermodynamic charges may be defined unambiguously. We explicitly demonstrate and illustrate our claim by computing the thermodynamic charges of two non-trivial supergravity solutions that were recently constructed: (1) the Polchinski–Strassler black brane that is dual to the deconfined phase of

N
=

1

*

theory, and (2) the CGLP black brane that asymptotes to the mass deformed Cvetič–Gibbons–Lü–Pope (CGLP) solution.
Three-dimensional Fabry–Pérot cavities sculpted on fiber tips using a multiphoton polymerization process
Authors: Smith Jonathan W , Williams Jeremiah C , Suelzer Joseph S , Usechak Nicholas G , Chandrahalim Hengky
Published: October 2020

This paper presents 3D Fabry–Pérot (FP) cavities fabricated directly onto cleaved ends of low-loss optical fibers by a two-photon polymerization (2PP) process. This fabrication technique is quick, simple, and inexpensive compared to planar microfabrication processes, which enables rapid prototyping and the ability to adapt to new requirements. These devices also utilize true 3D design freedom, facilitating the realization of microscale optical elements with challenging geometries. Three different device types were fabricated and evaluated: an unreleased single-cavity device, a released dual-cavity device, and a released hemispherical mirror dual-cavity device. Each iteration improved the quality of the FP cavity’s reflection spectrum. The unreleased device demonstrated an extinction ratio around 1.90, the released device achieved 61, and the hemispherical device achieved 253, providing a strong signal to observe changes in the free spectral range of the device’s reflection response. The reflectance of the photopolymer was also estimated to be between 0.2 and 0.3 over the spectrum of interest. The dual-cavity devices include both an open cavity, which can interact with an interstitial medium, and a second solid cavity, which provides a static reference reflection. The hemispherical dual-cavity device further improves the quality of the reflection signal with a more consistent resonance, and reduced sensitivity to misalignment. These advanced features, which are very challenging to realize with traditional planar microfabrication techniques, are fabricated in a single patterning step. The usability of these FP cavities as thermal radiation sensors with excellent linear response and sensitivity over a broad range of temperature is reported. The 3D structuring capability the 2PP process has enabled the creation of a suspended FP heat sensor that exhibited linear response over the temperature range of 20 ºC –120 ºC; temperature sensitivity of ∼50 pm ºC−1 at around 1550 nm wavelength; and sensitivity improvement of better than 9x of the solidly-mounted sensors.
Inner shell photofragmentation of 2Cl-pyrimidine studied by mass spectrometry and electron–ion coincidence experiments
Authors: Bolognesi Paola , Kettunen Antti , O’Keeffe Patrick , Richter Robert , Cartoni Antonella , Casavola Anna Rita , Castrovilli Mattea C , Tosic Sanja , Marinkovic Bratislav P , Avaldi Lorenzo
Published: October 2020

Photoelectron spectroscopy, mass spectrometry and electron–ion coincidence experiments combined with tunable synchrotron radiation have been used to study the decay and fragmentation of 2Cl-pyrimidine after Cl(2p), C(1s) and N(1s) excitations. The goal is to investigate how the state- and site-selected excitation and the chemical environment affect the fragmentation paths of the molecule and to make a comparison with fragmentation induced by direct valence ionization. It has been found that the site-selective inner shell excitation affects the branching ratio of the fragments, while the particular fragmentation channels of the cation are determined by the final state populated in the resonant decay of the core excited states. Effects of nuclear motion in the core excited states and the possible ultrafast molecular dissociation following the Cl(2p → σ
*) core excitation are discussed.
Development of an application to visualise the spread of scattered radiation in radiography using augmented reality
Authors: Nishi Kazuki , Fujibuchi Toshioh , Yoshinaga Takashi
Published: October 2020

As radiation is widely used in medical institutions, the lack of radiation protection education for health workers increases the risk of radiation exposure. The purpose of this study is to develop an application for radiation medical personnel that visualises the distribution of scattered radiation by using augmented reality (AR). The irradiation conditions for mobile chest and pelvic radiography were simulated using Monte Carlo simulations (Particle and Heavy Ion Transport code System). Monte Carlo results were verified using physical measurements. The behaviour of scattered radiation was displayed three-dimensionally in virtual reality using ParaView. Subsequently, an application to visualise scattered rays was developed in Unity for tablet devices. An application with a sense of reality was developed by visualising the scattered radiation distribution of a mobile imaging in a real space in AR in a three-dimensional size, which is close to the actual size. The radiation dose could be estimated at any position and the behaviour of scattered radiation became easier to understand.
A facile synthesis of CoMn2O4 nanosheets on reduced graphene oxide for non-enzymatic glucose sensing
Authors: Dong Min , Hu Hongli , Ding Shujiang , Wang Changcheng , Li Long
Published: October 2020

A non-enzymatic sensor nanomaterial which is composed of ultra-thin scaly CoMn2O4 nanosheets grown on the surface of reduced graphene oxide sheets (CoMn2O4 NSs/rGO) has been successfully synthesized by a simple method for glucose sensing. The morphology and elemental composition of CoMn2O4 NSs/rGO are researched by means of x-ray diffraction, field emission scanning electron microscope, and transmission electron microscope. Cyclic voltammetry and amperometry are used to analyse the glucose oxidation characteristics of the material. The test results show that the non-enzymatic glucose sensor based on CoMn2O4 NSs/rGO has excellent glucose sensing performance, exhibiting a wide linear range of 0.1–30 mM with high sensitivity of 6830.5 μA mM−1 cm−2, which is better than other glucose sensors. In addition, the CoMn2O4 NSs/rGO sensor has superior anti-interference and stability. More importantly, the sensor can be applied to the measurement of real sample, which makes it have the potential to become a reliable clinical glucose sensor.
Selective growth of ZnO nanorods by thickness contrast in In-doped ZnO quantum dots seed layer
Authors: Baek Seung-Eun , Khang Dahl-Young
Published: October 2020

Selective growth of ZnO nanorods (NRs) have been demonstrated using thickness contrast in In-doped ZnO (IZO) quantum dot (QD) seed layer. The use of IZO QD as a seed layer has enabled the direct growth of ZnO NRs on soft substrates such as polyethylene terephthalate (PET) and polydimethylsiloxane (PDMS). Depending on the annealing temperature, the seed layers show different grain sizes: as the annealing temperature increases, the seed grain size also increases accordingly. Interestingly, the hydrothermal growth of ZnO NRs has been found to depend on the seed grain size: the larger grain seed sample shows earlier start of growth compared to smaller seed grain counterpart. The same growth behavior has been found in the growth of ZnO NRs on seed layers having different thickness, due again to the difference in seed grain size. To advantageously exploit the observed growth behavior, the IZO QDs seed layers have been patterned by soft lithographic technique, which led to the formation of alternating thin/thick region periodically. On this patterned seed surface, the thin regions showed earlier start of NRs growth compared to thick regions, enabling the spatially selective growth of ZnO NRs. When applied for acetone gas sensors, the selectively grown sample showed better performance than the non-selectively grown counterpart. The low resistance in air, due to increased amount of chemisorbed oxygen, has been found to be responsible for the inferior sensor performance with non-selectively grown sample.
Determining of the spring constant using Arduino
Authors: Çoban Atakan , Çoban Niyazi
Published: October 2020

In this study, the spring constant was determined within the scope of Hooke’s law. For this purpose, an Arduino MEGA, an HC-SR04 Ultrasonic Distance Sensor, and a 1 kg Load Cell Mass Sensor was used. Sensors and microprocessor are mounted on a plane. One end of the spring is mounted on the force sensor, and a wooden rod, perceived by the distance sensor, is mounted on the other end of the spring. In the data collection element of the study, the spring is slowly extended from its equilibrium position. In this process, elongation and spring force data are obtained with the help of Arduino. By means of the recorded values, graphs and equations relating to force-dependent elongation are determined. The spring constant is calculated by taking the first derivative of the determined force equation. Both a thin and a thick spring are used in the study. The spring constants of these springs are determined both individually and in series-parallel connection. In addition, the spring constant is determined by reducing the length of the thick spring. In the study, a theoretical calculation of the spring constants in cases where these springs are connected was also performed. For this theoretical calculation, spring constants based on the studies for thin and thick springs were used. There is a harmony between these calculationsand the experimental results when the springs are connected. This harmony confirms the accuracy and reliability of the results. The materials employed in this study have a very low total cost, and are quite easy to obtain. Within the scope of the study, a system is designed using technology and engineering skills falling within the scope of physical research, and the results are achieved by using the collected data from mathematical equations. This process directly serves the aims of the STEM Education approach. It is very important in relation to educating individuals with twenty-first century skills to perform these and similar practical experiments in classroom environments.
Analytical modeling for design and performance evaluations of a new low aspect ratio soft rotary pneumatic actuator
Authors: Min Lee Young , Jin Lee Hyuk , Moon Hyungpil , Ryeol Choi Hyouk , Choon Koo Ja
Published: October 2020

This paper presents a different type of rotary actuator in contrast to conventional rotary actuators that operate by fiber wound in the form of a helix on a cylinder-shaped elastomer. Our actuator has a fiber set placed in the rθ plane of an elastomer in the form of an annulus, this elastomer expands under pneumatic pressure input to deliver rotation and torque to a rigid shaft connected to the elastomer’s inner circumference. In addition to the description and testing of our actuator’s novel mechanism, the main contribution of this paper is the design’s verification through a theoretical analysis of the rotational motion generated by the mutual influence of the elastomer and inflexible fiber elements. We also show how the design parameters are related to the wound angle of how much the fiber set inserted in the elastomer was wound in a spiral configuration. For various wound angles, computer simulation and experiments were carried out to prove the validity of our analytical model. Further experiments were conducted to measure the performance of the actuators by conducting a torque test with rotation set to zero.
Surface termination effects on the electrical characteristics of La2O3/Al2O3 nanolaminates deposited by atomic layer deposition*
Authors: Fan Ji-Bin , Ling Shan-Ya , Liu Hong-Xia , Duan Li , Zhang Yan , Guo Ting-Ting , Wei Xing , He Qing
Published: October 2020

Effects of initial surface termination on electrical characteristics of La2O3/Al2O3 nanolaminates deposited by atomic layer deposition are studied by conductive atomic force microscopy working in contact mode and standard electrical characterization methods. It is found that, compared with La2O3/Al2O3 nanolaminates with LaO
x
as termination, lower interface trap density, less current leakage spots, and higher breakdown voltage are obtained in the La2O3/Al2O3 nanolaminates with AlO
x
as termination after annealing. A clear promotion of interface silicate layer is observed for La2O3/Al2O3 nanolaminates with AlO
x
as termination compared with LaO
x
as termination under the same annealing condition. In addition, the current conduction mechanism in La2O3/Al2O3 nanolaminates is considered as the Poole–Frenkel conduction. All results indicate that the AlO
x
is a more appropriate termination to deposit La2O3/Al2O3 nanolaminates on Si substrate, which is useful for the high-κ process development.