bluuebunny/crossref_metadata_2025 huggingface dataset:
A Catalytic One-Pot Synthesis of Indolyl Cyclobutanones
Authors: Secci Francesco , Porcu Stefania , Rodriguez Carla Aira , Frongia Angelo
Published: December 2020

A general strategy for the synthesis of indolyl cyclobutanones via a tandem Brønsted acid catalyzed 2-hydroxycyclobutanone activation–indole nucleophilic addition has been exploited. The procedure leads to a wide range of 2- and 3-functionalized indole derivatives in good to high yields with broad substrate scope.
Endoscopic Endonasal Transclival Odontoidectomy for Basilar Invagination: Operative Video and Technical Nuances
Authors: Liu James K. , Dodson Vincent N. , Zhao Kevin , Eloy Jean Anderson
Published: December 2020

Basilar invagination is a congenital or acquired craniovertebral junction abnormality where the tip of the odontoid process projects through the foramen magnum which can cause severe symptomatic compression of the brainstem and spinal cord. If left untreated, patients can develop progressive quadriparesis. Traditionally, basilar invagination can be treated with cervical traction and posterior stabilization. However, in irreducible cases, anterior decompression via a transoral or endonasal approach may be necessary. In this operative video, we demonstrate an endoscopic endonasal transclival approach for odontoidectomy to successfully treat a 37-year-old female with severe basilar invagination causing symptomatic compression on the cervicomedullary junction resulting in unsteady gait and motor weakness. The patient had Klippel–Feil syndrome where the C1 arch was assimilated to the foramen magnum and transclival drilling was needed to adequately access the odontoid process for removal. A second-stage posterior occipitocervical stabilization and fusion was performed the following day. Immediate postoperative imaging showed excellent decompression of the cervicomedullary junction. Postoperatively, the patient had significant improvement in gait and motor strength in all extremities, and was ambulating independently without assistance at 1 year after surgery. The endoscopic endonasal transclival odontoidectomy is a useful strategy to treat severe irreducible basilar invagination causing symptomatic neural compression. The surgical technique and nuances are described in a step-by-step fashion in this illustrative operative video.

The link to the video can be found at: https://youtu.be/HL4K7KqJEJM.
Far Lateral Transcondylar Transtubercular Approach for Microsurgical Resection of Foramen Magnum Meningioma: Operative Video and Technical Nuances
Authors: Liu James K. , Dodson Vincent N. , Meybodi Ali T.
Published: December 2020

Surgical access to the ventral foramen magnum remains a technical challenge. With large lesions in this region compressing the brainstem and distorting the regional neurovascular relationships, formulating a surgical plan and its appropriate execution have crucial importance in achieving favorable outcomes. While the endoscopic endonasal approaches have gained increasing attention to access the clivus and the ventral brainstem, foramen magnum meningiomas are still preferred to be removed via an approach that obviates a trajectory through the nasopharyngeal mucosa. Therefore, the far lateral approach remains one of the most practical approaches for these challenging lesions. This operative video demonstrates the use of the far lateral transcondylar transtubercular approach to remove a large meningioma in the ventral foramen magnum in a 63-year-old male with progressive cervical myelopathy, presenting as spastic quadriparesis without any cranial nerve abnormality. Using a right-sided far lateral transcondylar transtubercular approach, the meningioma was exposed within the cerebellomedullary gutter engulfing the vertebral artery and distorting the course of the adjacent cranial nerves. Using the different corridors identified between the vertebral artery, spinal accessory, vagus, and hypoglossal nerves, multiple angles of attacks to the tumor were established and utilized to resect the lesion. A gross total resection was achieved and the patient was neurologically intact without any neurological deficits. This video demonstrates the importance of understanding the intricacies of neurovascular anatomy of the cervicomedullary region (i.e., the various triangles formed between these structures), and the effective use of these corridors to safely and efficiently remove a challenging ventral foramen magnum meningioma with neurovascular involvement, while preserving cranial nerve function. The surgical technique and nuances are described in a step-by-step fashion in this illustrative operative video.

The link to the video can be found at: https://youtu.be/s1dFhuaRSt8.
Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2): Codon Usage and Replicative Fitness
Authors: Kanduc Darja
Published: December 2020

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) codon usage, as shown by the polyprotein coding sequence, shows better translation potential in the human host when compared with human coronavirus OC43 (HCoV-OC43) codon usage. Such translational advantage might facilitate SARS-CoV-2 replication, immunogenicity, and pathogenicity, thus also accounting for the less harmful character of HCoV-OC43 infection.
De Novo Ring Chromosome 15: Molecular Cytogenetic and Clinical Characterization of First Case from Saudi Arabia
Authors: Alhashem Amal , Alazmeh Saria , Barakat Ayla , Alfares Ahmed , Elghezal Hatem
Published: December 2020

Ring chromosome 15 is a rare chromosomal disorder, which usually occurs during early embryonic development via spontaneous errors and has variable presentation. To date, 89 cases of this condition have been reported. This case report describes a 5-year-old Saudi boy who was diagnosed as having de novo 46,XY,r(15). The patient presented with short stature, speech delay, café au lait spots, and facial dysmorphic features, together with new findings of left crossed fused renal ectopia and 11 ribs. This presentation was compared with the findings of cases reported previously.
Melioidosis: A Fulminant Infection in a Patient with Uncontrolled Diabetes
Authors: Baikunje Nandakishore , Gangaramajalu Suresh , Hosmane Giridhar Belur
Published: December 2020

Melioidosis is an endemic infection in Southeast Asia and Northern Australia commonly manifesting with pneumonia and localized skin infection. Though most exposures do not lead to severe illness, a fulminant infection can occur among patients with risk factors. A 59-year-old male presented with cough with expectoration and fever for 1 week. He had diabetes for 10 years with poorly controlled blood sugars. Contrast-enhanced computerized tomography (CECT) of thorax showed right upper lobe consolidation with diffuse ground-glass opacities in right upper lobe along with microabscesses in liver and spleen. Sputum culture and Xpert mycobacterium tuberculosis complex and resistance to rifampin (MTB/RIF) for tuberculosis were negative. Bronchoalveolar lavage culture grew Burkholderia pseudomallei. He was treated with initial intensive therapy with injection amoxicillin-clavulanic acid for 2 weeks and subsequently started on eradication therapy with tablet trimethoprim-sulfamethoxazole. Diagnosis of melioidosis should be considered in a patient of pneumonia with multiorgan involvement in an endemic area, especially with underlying risk factors.
Investigating the Effect of Gift-Giving on Patient's Behavior in the Pediatric Clinic of Dr. Sheikh Hospital of Mashhad
Authors: Ghodsi Alireza , Azarfar Anoush , Sarabi Mehrdad , Ravanshad Yalda , Esmaeeli Mohammad , Salahi Zeinab
Published: December 2020

Objective The aim of this study was to investigate the effect of gift-giving on the patient's behavior. We hypothesized that it is possible to improve the relationship between a doctor and a patient by giving the visiting patient gifts as such gesture may boost her confidence in the doctor, help built personable relationship, and thereby facilitate examination.

Materials and Methods For this study, we selected pediatric patients aged 3 to 12 years, who visited pediatric clinic of Dr. Sheikh Hospital of Mashhad. Patients were divided into two groups. One group received a gift (stickers) after examination and prescription. The criterion for evaluating patients' behavior was parental opinion, and the questionnaire was completed in two stages. The Chi-square test was used to compare the behavior of the patients, and data were analyzed by SPSS software.

Results In total, 194 people participated that included 74 boys and 120 girls. There was a significant difference at the 99% level between the control and intervention groups in the variables of stress, the desire to go to the doctor, fear reduction between visits, regular use of the drug, cooperation with the doctor, the desire for re-referral, and insistence on referring to the same physician after receiving the gift. There was also a significant difference at the 95% level between two groups in terms of the expression of physical problems by kids. However, there was no significant difference in the level of stress before the receipt of the gift, the desire and willingness to refer to the doctor before receiving the gift, and the waiting time tolerance to enter the doctor's room.

Conclusion We found that gifts motivate more appropriate behaviors in kids when referring to a doctor.
Tailoring femtosecond hot-electron pulses for ultrafast spin manipulation
Authors: Bergeard N. , Hehn M. , Carva K. , Baláž P. , Mangin S. , Malinowski G.
Published: December 2020

We have measured the hot-electron-induced demagnetization of a [Co/Pt]2 multilayer in M(x nm)/Cu(100 nm)/[Co(0.6 nm)/Pt(1.1 nm)]2 samples depending on the nature of the capping layer M and its thickness x. We found out that a Pt layer is more efficient than [Co/Pt]X, Cu, or MgO layers in converting infrared (IR) photon pulses into hot-electron pulses at a given laser power. We also found out that the maximum relative demagnetization amplitude is achieved for M(x) = Pt (7 nm). Our experimental results show qualitative agreement with numerical simulations based on the superdiffusive spin transport model. We concluded that the maximum relative demagnetization amplitude, which corresponds to the highest photon conversion into hot electrons, is an interplay between the IR penetration depth and the hot-electron inelastic mean free path within the capping layer.
Real-time interrogation of fiber optic biosensor using TiO2 coated etched long-period grating
Authors: Singh Mandeep , Raghuwanshi Sanjeev Kumar
Published: December 2020

In this work, a TiO2 coated etched long-period grating (e-LPG) fiber optic biosensor is developed for the detection of Escherichia coli (E. coli) bacteria in food items. Label-free Escherichia coli bacteria monitoring is done over the detection range of 0 cfu/ml–50 cfu/ml using an advanced spectral interrogation mechanism. The thin film deposition of 40 nm TiO2 over the e-LPG is confirmed by the microscopy method, such as scanning electron microscopy. In our proposed biosensor design, T4-bacteriophage is covalently immobilized over the TiO2 coated fiber surface. This biosensor system has reached sensitivity at 2.55 nm/RIU. Our experiments confirm the resolution and the limit of detection (3σ/S) of 0.0039 RIU and 10.05 ppm, respectively. The proposed biosensor with enhanced sensitivity is suitable for monitoring harmful pathogens/infectious agents in various food products.
Removing artifacts in polarizable embedding calculations of one- and two-photon absorption spectra of fluorescent proteins
Authors: Grabarek Dawid , Andruniów Tadeusz
Published: December 2020

The multiscale calculations involving excited states may suffer from the electron spill-out (ESO) problem. This seems to be especially the case when the environment of the core region, described with the electronic structure method, is approximated by a polarizable force field. The ESO effect often leads to incorrect physical character of electronic excitations, spreading outside the quantum region, which, in turn, results in erroneous absorption spectra. In this work, we investigate means to remove the artifacts in one-photon absorption (OPA) and two-photon absorption (TPA) spectra of green and yellow fluorescent protein representatives. This includes (i) using different basis sets, (ii) extending the core subsystem beyond the chromophore, (iii) modification of polarization interaction between the core region and its environment, and (iv) including the Pauli repulsion through effective core potentials (ECPs). Our results clearly show that ESO is observed when diffuse functions are used to assemble the multielectron wave function regardless of the exchange–correlation functional used. Furthermore, extending the core region, thus accounting for exchange interactions between the chromophore and its environment, leads to even more spurious excited states. Also, damping the interactions between the core subsystem and the polarizable force field is hardly helpful. In contrast, placing ECPs in the position of sites creating the embedding potential leads to the removal of artificious excited states that presumably should not be observed in the OPA and TPA spectra. We prove that it is a reliable and cost-effective approach for systems where the covalent bond(s) between the core region and its environment must be cut.
Unifying the optical and electrical properties of amorphous carbon: application to hopping photoconductivity and memristance
Authors: Zhao Zijun C. , Raeber Thomas J. , Murdoch Billy J. , Partridge James G. , McCulloch Dougal G. , McKenzie David R.
Published: December 2020

Amorphous carbon films with an intermediate content of sp3 atoms are finding applications as resistive switches in devices for bio-sensing and for neuromorphic pattern recognition. To understand resistive switching and photoconductivity in amorphous semiconductors dominated by hopping conduction, we present a theory that unifies the optical and electronic properties. The theory considers all of the states to be localized to various extents instead of being extended electronic states. The electronic density of states (eDOS) is modeled with Gaussian functions, symmetric in energy around the Fermi energy. A “hopping mobility” between localized states that is explicitly both energy and temperature dependent is introduced. We describe an example application to amorphous carbon films prepared by using high power impulse magnetron sputtering that have a range of sp3 hybridization fractions of the carbon atoms. The electronic bandgaps of the films are observed to correlate with their optical bandgaps. The eDOS is benchmarked against optical property measurements made by ellipsometry. The theory explains the temperature dependence of the resistivity and predicts that the films should show a temperature dependent hopping photoconductivity. Measurements confirm the presence of the photoconductivity and reveal its spectral dependence. A link is made between persistent hopping photoconductivity and resistive switching.
Generalized mode-coupling theory of the glass transition. I. Numerical results for Percus–Yevick hard spheres
Authors: Luo Chengjie , Janssen Liesbeth M. C.
Published: December 2020

Mode-coupling theory (MCT) constitutes one of the few first-principles-based approaches to describe the physics of the glass transition, but the theory’s inherent approximations compromise its accuracy in the activated glassy regime. Here, we show that microscopic generalized mode-coupling theory (GMCT), a recently proposed hierarchical framework to systematically improve upon MCT, provides a promising pathway toward a more accurate first-principles description of glassy dynamics. We present a comprehensive numerical analysis for Percus–Yevick hard spheres by performing explicitly wavenumber- and time-dependent GMCT calculations up to sixth order. Specifically, we calculate the location of the critical point, the associated non-ergodicity parameters, and the time-dependent dynamics of the density correlators at both absolute and reduced packing fractions, and we test several universal scaling relations in the α- and β-relaxation regimes. It is found that higher-order GMCT can successfully remedy some of MCT’s pathologies, including an underestimation of the critical glass transition density and an overestimation of the hard-sphere fragility. Furthermore, we numerically demonstrate that the celebrated scaling laws of MCT are preserved in GMCT and that the predicted critical exponents manifestly improve as more levels are incorporated in the GMCT hierarchy. Although formally the GMCT equations should be solved up to infinite order to reach full convergence, our finite-order GMCT calculations unambiguously reveal a uniform convergence pattern for the dynamics. We thus argue that GMCT can provide a feasible and controlled means to bypass MCT’s main uncontrolled approximation, offering hope for the future development of a quantitative first-principles theory of the glass transition.
Amorphous ultra-wide bandgap ZnOx thin films deposited at cryogenic temperatures
Authors: Zubkins M. , Gabrusenoks J. , Chikvaidze G. , Aulika I. , Butikova J. , Kalendarev R. , Bikse L.
Published: December 2020

Crystalline wurtzite zinc oxide (w-ZnO) can be used as a wide bandgap semiconductor for light emitting devices and transparent or high temperature electronics. The use of amorphous zinc oxide (a-ZnO) can be an advantage in these applications. In this paper, we report on x-ray amorphous a-ZnOx thin films (∼500 nm) deposited at cryogenic temperatures by reactive magnetron sputtering. The substrates were cooled by a nitrogen flow through the copper substrate holder during the deposition. The films were characterized by x-ray diffraction, Raman, infrared, UV–Vis-near-infrared spectroscopies, and ellipsometry. The a-ZnOx films on glass and Ti substrates were obtained at the substrate holder temperature of approximately −100 °C. New vibration bands at 201, 372, and 473 cm−1 as well as O–H stretch and bend absorption bands in the a-ZnOx films were detected by Fourier transform infrared spectroscopy. Raman spectra showed characteristic ZnO2 peaks at 386 and 858 cm−1 attributed to the peroxide ion O22− stretching and libration modes, respectively. In addition, the films contain neutral and ionized O2 and O2− species. The a-ZnOx films are highly transparent in the visible light range (≈87%) and exhibit a refractive index of 1.68 at 2.25 eV (550 nm). An optical bandgap is 4.65 eV with an additional band edge absorption feature at 3.50 eV. It has been shown that the deposition on actively cooled substrates can be a suitable technique to obtain low temperature phases that cannot be deposited at room temperature.
Optical studies of nitrogen plasma for molecular beam epitaxy of InN
Authors: Pérez-Caro M. , Ramírez-López M. , Hernández-Méndez S. , Rodríguez B. A. G. , Casallas-Moreno Y. L. , Gallardo-Hernández S. , López-López M.
Published: December 2020

We report on the optical characterization of a nitrogen plasma source based on radiofrequency (RF) used to grow III-nitride materials by molecular beam epitaxy (MBE). Optical emission spectroscopy (OES) was used to study the nitrogen plasma response as a function of the RF power applied and the flow rate of molecular nitrogen. Analysis of the intensities of spectral signals assigned to atomic and molecular species and the ratio of these intensities is performed in detail. The OES results show that the plasma source studied is sensitive to the RF power applied to produce an atomic nitrogen signal, while varying the incoming flow impacts the signal of metastable nitrogen molecules; this outcome allows for the determination of conditions under which certain types of nitrogen species are favored over others. InN films were grown on AlN-buffered Si(111) substrates by MBE under different plasma operational parameters, where, according to the OES studies, atomic nitrogen or excited molecular nitrogen is favored in the plasma. In situ reflection high-energy electron diffraction, scanning electron microscopy, and x-ray diffraction techniques were employed to characterize the InN samples. It is found that the surface morphology of the InN films is highly sensitive to the plasma conditions. A transition in the growth mode from smooth compact films to coalesced islands and columnar structures is observed when the dominant reactive species is atomic nitrogen or excited molecular nitrogen. The results of the characterization are discussed and correlated with the reactive nitrogen species present in the plasma.
Local measurements of domain wall-induced self-heating in released PbZr0.52Ti0.48O3 films
Authors: Lundh James Spencer , Zhu Wanlin , Song Yiwen , Ko Song Won , Fragkiadakis Charalampos , Mardilovich Peter , Trolier-McKinstry Susan , Choi Sukwon
Published: December 2020

The motion of domain walls in lead zirconate titanate (PZT) produces both nonlinearity and hysteresis. While measurements of the resulting self-heating under an electric field drive are well known in bulk ferroelectric ceramics, self-heating effects in PZT films may differ from those in bulk ceramics due to a combination of reduced domain wall motion, differences in heat dissipation associated with substrates or passive elastic layers, and differences in typical drive fields. Here, it is shown that the thermal imaging of the test structures of PZT piezoelectric microelectromechanical systems using techniques such as infrared thermography and thermoreflectance thermal imaging suffers from motion-induced artifacts. These limitations were overcome via nanoparticle-assisted Raman thermometry with a spatial resolution of ∼1 μm. To acquire the local temperature distribution quantitatively, anatase nanoparticles were distributed across the electrodes and actuating PZT diaphragm. The temperature rise of the test structures increased as the operating frequency, voltage amplitude, and slew rate increased. As expected, the largest temperature rises were induced due to self-heating associated with domain switching under bipolar operation. In addition, a higher voltage amplitude testing revealed non-uniform temperature distributions across the piezoelectric actuator, suggesting that AC Joule heating can induce significant heat generation (ΔT ∼ 30 K) under high electric fields (∼390 kV/cm).
Dielectric, energy storage, and loss study of antiferroelectric-like Al-doped HfO2 thin films
Authors: Payne Alexis , Brewer Owen , Leff Asher , Strnad Nicholas A. , Jones Jacob L. , Hanrahan Brendan
Published: December 2020

Antiferroelectric thin films have properties ideal for energy storage due to their lower losses compared to their ferroelectric counterparts as well as their robust endurance properties. We fabricated Al-doped HfO2 antiferroelectric thin films via atomic layer deposition at variable thicknesses (20 nm or 50 nm) with varying dopant concentrations (4 at. % or 8 at. %). 50 nm thick 8 at. % Al-doped HfO2 showed a maximum energy storage density of 63 J/cm3 while maintaining an efficiency of 85%. A study comparing these thin films revealed thicker films allowed for higher operating electric fields and thus higher energy storage densities at operating voltage. The loss tangents of the thin films at operating voltage were under 2% over the range of −4 to 4 MV/cm and at frequencies ranging from 500 Hz to 100 kHz. Reliability studies showed the thin films endure up to 106–107 cycles and the breakdown field of the films yielded Weibull moduli greater than 6 for all our thin films. The Weibull modulus provides a measurement of the consistency of the breakdown strength from sample to sample, with higher moduli indicating a more invariable result. These electrical characteristics along with the thin film's cycling endurance and reliability make antiferroelectric-like Al-doped thin films a promising material for energy storage applications.
Delays induced cluster synchronization in chaotic networks
Authors: Nathe Chad , Huang Ke , Lodi Matteo , Storace Marco , Sorrentino Francesco
Published: December 2020

We study networks of coupled oscillators and analyze the role of coupling delays in determining the emergence of cluster synchronization. Given a network topology and a particular arrangement of the coupling delays over the network connections, different patterns of cluster synchronization may emerge. We focus on a simple ring network of six bidirectionally coupled identical oscillators, for which with two different values of the delays, a total of eight cluster synchronization patterns may emerge, depending on the assignment of the delays to the ring connections. We analyze stability of each of the patterns and find that for large enough coupling strength and specific values of the delays, they can all be stabilized. We construct an experimental ring of six bidirectionally coupled Colpitts oscillators, with delayed connections obtained by coupling the oscillators via RF cables of appropriate length. We find that experimental observations of cluster synchronization are in essential agreement with theoretical predictions. We also verify our theory in a fully connected network of fifty nodes for which connections are randomly assigned to be either undelayed or delayed with a given probability.
A study of photophoretic trapping exploiting motional resonances of trapped particles induced by wideband excitation
Authors: Sil Souvik , Basak Prithviraj , Pahi Anita , Banerjee Ayan
Published: December 2020

Photophoretic forces confine particles by a combination of levitation and active trapping. To generate the latter, the component of photophoretic force transverse to gravity generates a torque, which leads to complex rotation of the particle, thereby generating a restoring force. This force has not been understood quantitatively. In this paper, we study this component of photophoretic force by trapping a single absorbing particle using a loosely focused Gaussian laser beam and modulating the trap-center spatially using a superposition of multiple sinusoidal frequencies applied to the trapping beam. We vary the modulation amplitude in proportion to the excitation frequency so as to compensate for the reduced particle response at higher frequencies and thus obtain an almost constant response of the particle over the entire excitation range. We use the amplitude and phase response to determine the resonance frequency and the trap stiffness—which we study as a function of laser power and the intensity experienced by trapped particles of different sizes. We observe that, while the trapping stiffness is proportional to laser power, the optical intensity experienced by a particle at different powers is the same. This is reasonable in order to facilitate optical levitation but implies that the trap stiffness actually depends on an “effective intensity,” which may be a combination of the particle accommodation coefficient and the laser power.
Mg acceptor doping in MOCVD (010)
β
-Ga2O3
Authors: Feng Zixuan , Bhuiyan A F M Anhar Uddin , Kalarickal Nidhin Kurian , Rajan Siddharth , Zhao Hongping
Published: December 2020

In this Letter, in situ Mg doping in β-Ga2O3 was demonstrated via metalorganic chemical vapor deposition (MOCVD) epitaxy. The electrical insulating property of the Mg acceptors in β-Ga2O3 was found to be intrinsically activated in the as-grown Mg-doped β-Ga2O3 thin films. Growth conditions for MOCVD β-Ga2O3 were further explored and optimized at a lower growth temperature regime, leading to a better confinement of the Mg-doping profile. Detailed analysis of Mg diffusion characteristics revealed a diffusion barrier energy Ebarrier ∼ 0.9 eV for Mg in MOCVD β-Ga2O3, which is likely related to an interstitial-assisted process. Surface morphologies and electron transport were characterized on samples grown with different growth temperatures and Mg doping levels. The MOCVD growth method demonstrated its feasibility to grow semi-insulating Mg-doped β-Ga2O3 epilayers with controllable Mg incorporation while maintaining good material quality and smooth surface morphology. From capacitance-voltage charge profiling, it is verified that the Mg-doped buffer layer grown at the substrate-epilayer interface could effectively compensate the charge accumulation at the interface. The in situ acceptor doping of Mg in MOCVD β-Ga2O3 will provide versatility for designing β-Ga2O3 power devices.
Direct observation of the magnetic ordering process in the ferromagnetic semiconductor Ga1−xMnxAs via soft x-ray magnetic circular dichroism
Authors: Takeda Yukiharu , Ohya Shinobu , Pham Nam Hai , Kobayashi Masaki , Saitoh Yuji , Yamagami Hiroshi , Tanaka Masaaki , Fujimori Atsushi
Published: December 2020

In order to understand the mechanism of the ferromagnetism in the ferromagnetic semiconductor Ga1−xMnxAs [(Ga,Mn)As], we have investigated the magnetic behavior on a microscopic level through systematic temperature (T)- and magnetic field (H)-dependent soft x-ray magnetic circular dichroism (XMCD) experiments at the Mn L2,3 absorption edges. The T and H dependences of XMCD intensities have been analyzed using a model consisting of the ferromagnetic (FM), paramagnetic, and superparamagnetic (SPM) components. Intriguingly, we have found a common behavior for the ferromagnetic ordering process in (Ga,Mn)As samples with different Mn concentrations (4% and 10.8%) and different Curie temperature (TC) values (65, 120, and 164 K). In particular, the SPM component develops well above TC, indicating that local FM regions are formed well above TC. The present findings indicate that the onset of ferromagnetic ordering is triggered by local electronic states around the substitutional Mn ions rather than uniform electronic states considered by mean-field theories. Insight into the most representative ferromagnetic semiconductor, (Ga,Mn)As, provided by the present study will be an important step in understanding the mechanism of ferromagnetic ordering in various ferromagnetic semiconductor families.
High Fermi velocities and small cyclotron masses in LaAlGe
Authors: Hu Zhixiang , Du Qianheng , Liu Yu , Graf D. , Petrovic C.
Published: December 2020

We report quantum oscillation measurements of LaAlGe, a Lorentz-violating type-II Weyl semimetal with tilted Weyl cones. Very small quasiparticle masses and very high Fermi velocities were detected at the Fermi surface. Whereas three main frequencies have been observed, the angular dependence of two Fermi surface sheets indicates possible two-dimensional (2D) character despite the absence of the 2D structural features such as van der Waals bonds. Such conducting states may offer a good platform for low-dimensional polarized spin current in magnetic RAlGe (R = Ce, Pr) materials.
Tests of accuracy for computed magnetic properties via off-diagonal hypervirial relations
Authors: Lazzeretti Paolo
Published: December 2020

Most of the methods presently available to investigate the molecular magnetic response work extremely well for the computation of properties, such as magnetizability and nuclear magnetic shielding, but they provide insufficiently accurate current density maps, in that they do not guarantee exact conservation, leading to unphysical features in maps. The present study starts from the results obtained by Epstein and Sambe and moves forward to generalize them. An off-diagonal hypervirial relationship, connecting the matrix elements of a given differentiable function of position f(r) to its derivatives ∇f(r), via the anticommutator ∇αf,p^α+ with the canonical momentum operator p^, has first been proven. Afterward, this relationship is applied to show that the equations proposed by Sambe to check the quality and conservation of computed electronic current densities can be obtained as particular cases of this general theorem, with a substantial gain in computational efficiency. Connections with previous work by Arrighini, Maestro, and Moccia are outlined, and the implications that hint at future work are discussed.
Conservation of quolls (Dasyurus spp.) in captivity – a review
Authors: Old Julie M. , Stannard Hayley J.
Published: December 2020

Quolls are carnivorous marsupials in the family Dasyuridae with characteristic white spots. They are distributed throughout Australia and New Guinea, but uncommonly seen due to their mostly nocturnal solitary nature, and large home ranges. All Australian quolls are listed as ‘near threatened’ or ‘endangered’ at state, national and international levels, largely due to human-induced threats. Threats include introduced predators, habitat loss through clearing and modifications including changed fire regimes, disease, human persecution, vehicle collisions and accidental or targeted poisoning by humans and cane toads (Rhinella marina). Conservation efforts that have focussed on reducing introduced predators, and minimising the impact of cane toads, have aided some translocations, hence species recovery in some local areas of Australia has occurred. Where species conservation has required captive breeding for translocation, successful captive management has been crucial. We summarise research conducted in captivity on aspects of birth and development, health and disease, and blood and nutrition parameters of quolls, and suggest future directions for research. Further research on captive and wild quoll populations will benefit future translocations, reintroductions and conservation through increased knowledge, improved maintenance and husbandry of captive colonies, and monitoring of wild populations.
Transforming yeast peroxisomes into microfactories for the efficient production of high-value isoprenoids
Authors: Dusséaux Simon , Wajn William Thomas , Liu Yixuan , Ignea Codruta , Kampranis Sotirios C.
Published: December 2020

Significance

Monoterpenoids, monoterpene indole alkaloids, and cannabinoids are highly valued for their fragrant and therapeutic properties, but sourcing them from nature or deriving them from petrochemicals is no longer sustainable. However, sustainable production of these compounds in engineered microorganisms is mostly hampered by the limited availability of the main building block in their biosynthesis, geranyl diphosphate. Here, we overcome this challenge by engineering yeast peroxisomes as geranyl diphosphate-synthesizing microfactories and unlock the potential of yeast to produce a wide range of high-value isoprenoids. Conceptually, in this work we develop peroxisomes as synthetic biology devices that can be used for the modular assembly and optimization of complex pathways, adding an extra level of hierarchical abstraction in the systematic engineering of cell factories.
Prdm16
is a critical regulator of adult long-term hematopoietic stem cell quiescence
Authors: Gudmundsson Kristbjorn O. , Nguyen Nhu , Oakley Kevin , Han Yufen , Gudmundsdottir Bjorg , Liu Pentao , Tessarollo Lino , Jenkins Nancy A. , Copeland Neal G. , Du Yang
Published: December 2020

Significance

Regulation of quiescence is critical for the maintenance of adult HSCs, and the underlying mechanisms are poorly understood. Using a novel mouse conditional knockout allele of transcription factor gene
Prdm16
, we show that its deletion in the adult hematopoietic system led to a gradual loss of adult HSCs over time. This loss of adult HSCs was associated with their significantly increased cycling. We further found that
Prdm16
promotes the quiescence of adult HSCs by activating the transcription of HSC cell cycle inhibitors including
Cdkn1a
and
Egr1
. Our study identifies
Prdm16
as a critical regulator of adult HSC quiescence.
Implementing a Peer Recovery Coach Model to Reach Low-Income, Minority Individuals not Engaged in Substance use Treatment
Authors: Kleinman Mary B. , Doran Kelly , Felton Julia W. , Satinsky Emily N. , Dean Dwayne , Bradley Valerie , Magidson Jessica F.
Published: December 2020

Background

Low-income, racial/ethnic minority individuals face significant barriers in access to substance use (SU) treatment. Peer recovery coaches (PRCs), individuals with lived experience with substance use disorder (SUD), may be uniquely well suited to assist those encountering barriers to treatment. PRCs can also help reach those not engaged in treatment to promote harm reduction and support linkage-to-care when embedded in community rather than clinical settings. This study evaluated a community-based program in which a PRC facilitated linkage to and supported retention in SU treatment.

Methods

Guided by the RE-AIM framework, we evaluated implementation of the intervention in a community resource center (CRC) serving homeless and low-income residents of Baltimore City. We examined the reach, effectiveness, adoption, and implementation of this PRC model.

Results

Of 199 clients approached by or referred to the PRC, 39 were interested in addressing their SU. Of those interested in addressing SU, the PRC linked 64.1% ( n = 25) to treatment and was able to follow up with 59.0% ( n = 23) at prespecified time points after linkage (24–48 hours, 2 weeks, and 1 month). Fifty-two percent ( n = 13) of clients linked to SU treatment remained in treatment at 30 days post-linkage. Of clients who did not remain in treatment, 77% ( n = 10) continued contact with the PRC.

Conclusions

Results indicate the utility of the CRC's approach in linking people to treatment for SU and addressing barriers to care through work with a PRC. Findings also highlight important barriers and facilitators to implementation of this model, including the need for adaptation based on individual goals and fluctuations in readiness for treatment.
High Prevalence of Unmet Healthcare Need among People who use Illicit Drugs in a Canadian Setting with Publicly-Funded Interdisciplinary Primary Care Clinics
Authors: Moallef Soroush , Homayra Fahmida , Milloy M.-J. , Bird Lorna , Nosyk Bohdan , Hayashi Kanna
Published: December 2020

Background

People who use illicit drugs (PWUD) experience significant barriers to healthcare. However, little is known about levels of attachment to primary care (defined as having a regular family doctor or clinic they feel comfortable with) and its association with unmet healthcare needs in this population. In a Canadian setting that features novel publicly-funded interdisciplinary primary care clinics, we sought to examine the prevalence and correlates (including attachment to primary care) of unmet healthcare needs among PWUD.

Methods

Data were derived from two prospective cohort studies of PWUD in Vancouver, Canada between December 2017 and November 2018. Multivariable logistic regression was used to identify factors associated with self-reported unmet healthcare needs among participants reporting any health issues.

Results

In total, 743 (83.6%) of 889 eligible participants reported attachment to primary care and 220 (24.7%) reported an unmet healthcare need. In multivariable analyses, attachment to primary care at an integrated care clinic (adjusted odds ratio [AOR] = 0.14; 95% Confidence Interval [CI]: 0.06–0.34) was negatively associated with an unmet healthcare need, while being treated poorly at a healthcare facility (AOR = 5.50; 95% CI: 3.59–8.60) and self-reported chronic pain (AOR = 2.00, 95% CI: 1.30–3.01) were positively associated with an unmet healthcare need.

Conclusion

Despite the high level of attachment to primary care, a quarter of our sample reported an unmet healthcare need. Our findings suggest that multi-level interventions are required to address the unmet need, including pain management and integrated care, to support PWUD with complex health needs.
Theory of polarization-averaged core-level molecular-frame photoelectron angular distributions: I. A full-potential method and its application to dissociating carbon monoxide dication
Authors: Ota F , Yamazaki K , Sébilleau D , Ueda K , Hatada K
Published: December 2020

We present a theoretical study of the polarization-averaged molecular-frame photoelectron angular distributions (PA-MFPADs) emitted from the 1s orbital of oxygen atoms of dissociating dicationic carbon monoxide CO2+. Due to the polarization average, the contribution of the direct wave of the photoelectron, which represents the largest contribution to the MFPADs, is removed, so that the PA-MFPADs clearly show the details of the scattering image of the photoelectron. As a result, it is necessary to employ an accurate theory for the theoretical analysis of the continuum state. In this study, we apply a full-potential multiple scattering theory, where the space is partitioned into Voronoi polyhedra and truncated spheres, to take into account the electron charge density outside the physical atomic spheres. We do not use the spherical harmonic expansion of the cell shape functions to avoid divergence problems. The potentials in the scattering cells are computed using the multiconfigurational second-order perturbation theory restricted active space method to take into account the influence of the core hole in the electron charge density in the final state, so that a realistic relaxation can be achieved. We show that the full-potential treatment plays an important role in the PA-MFPADs at a photoelectron kinetic energy of 100 eV. In contrast, the PA-MFPADs are not sensitive to any type of major excited states in the Auger final state. We also study the dynamics of the CO2+ dissociation. We find that the PA-MFPADs dramatically change their shape as a function of the C–O bond length.
Transforming domain motion for 3D racetrack memory with perpendicular magnetic anisotropy
Authors: Honda Syuta , Sonobe Yoshiaki , Greaves Simon John
Published: December 2020

Domain-wall motion type magnetic memories are expected to be among the next generation of magnetic recording devices and vertical-NAND memories. In particular, three-dimensional race track memory (3D-RM), which extends vertically from a substrate is important for high integration. We propose a vertical 3D-RM loop consisting of two horizontal and two vertical nanowires in which the magnetic anisotropy is perpendicular to the substrate. The horizontal nanowires contain perpendicularly magnetized domains and Néel type domain walls (DWs). The vertical nanowires contain longitudinally magnetized domains with head-to-head or tail-to-tail DWs. DW motion is demonstrated using micromagnetic simulations based on the Landau–Lifshitz–Gilbert equation. We find that a DW can pass around a corner while deforming its own shape. The threshold current density to push a DW around a corner has a maximum value for wire thickness of about 10 nm.
Tunneling magnetoresistance in ensembles of ferromagnetic granules with exchange interaction and random easy axes of magnetic anisotropy
Authors: Beltukov Y M , Kozub V I , Shumilin A V , Stepina N P
Published: December 2020

We study the tunneling magnetoresistance in the ensembles of ferromagnetic granules with random easy axes of magnetic anisotropy taking into account the exchange interaction between granules. It is shown that due to the exchange interaction magnetoresistance is effectively decoupled from magnetization, i.e. the strongest negative magnetoresistance can be observed at the field where magnetization is almost saturated. Under some conditions, the sign of magnetoresistance can be reversed and tunneling magnetoresistance can become positive at certain magnetic fields. Our theory agrees with measurements of magnetoresistance in ensembles of Fe granules in SiC
x
N
y
matrix.
Validation and uncertainty analysis of a reduced self-calibrating method for pitch measurements of cylindrical gears
Authors: Keller F , Stein M , Kniel K
Published: December 2020

The three-rosette method is a well-established self-calibrating error-separation method used for highly accurate pitch calibrations of cylindrical gears on coordinate measuring machines or gear measuring machines. It is based on the principle of circle closure and uses multiple measurements in different relative positions of the gear with respect to the measuring device. However, since its measurement effort is proportional to the square of the number of teeth, the method is of limited usability for gears with a large number of teeth. In this paper, a reduced method which requires much fewer measurements is described. This method is based on the same error model and is still self-calibrating. The measurement uncertainties for this method are only slightly higher than for the complete method. After an introduction to the three-rosette method, this paper describes the impact of the number and choice of the measured relative positions on the measurement uncertainty. Moreover, the problem of an erroneously determined gear axis is addressed. Finally, the effectiveness of the reduced three-rosette method is shown in intercomparison measurements with four participants. The obtained E

n
scores show that the reduced three-rosette method allows pitch calibrations with nearly the same accuracy as can be achieved with the complete method. The reduced three-rosette method is part of the TraCIM online service (https://tracim.ptb.de) of the Physikalisch-Technische Bundesanstalt (PTB) allowing software manufacturers or calibration laboratories to obtain a certificate for their algorithms of the reduced three-rosette method after a successfully performed software test. Moreover, calibration laboratories can receive accreditation by the German national accreditation body (DAkkS) for pitch calibrations performed by using the reduced three-rosette method.
Subaperture stitching wavelength scanning interferometry for 3D surface measurement of complex-shaped optics
Authors: Seo Yong Bum , Joo Ki-Nam , Ghim Young-Sik , Rhee Hyug-Gyo
Published: December 2020

Subaperture stitching wavelength scanning interferometry with a high-accuracy multi-axis position stage is proposed for measuring complex surface shapes such as aspherical and freeform optics. Typical optical approaches suffer due to poor fringe visibility when it comes to complex-shaped optics. Our proposed technique allows a proper solution to this challenging issue by keeping the optical probe perpendicular to the surface slope, which provides good fringe visibility during the wavelength scan regardless of how steep the surface is. Also, the full-aperture surface map of a test sample can be obtained by stitching multiple subaperture measurement results with high precision. We tested and verified our method by measuring several representative samples and comparing the measurement results with a well-established stylus method.
Antimony oxide nanostructures in the monolayer limit: self-assembly of van der Waals-bonded molecular building blocks
Authors: Märkl Tobias , Salehitaleghani Sara , Le Ster Maxime , Kowalczyk Pawel J , Wang Xiaoxiong , Wang Peng , Snyder Matthew , Bian Guang , Chiang Tai-Chang , Brown Simon A
Published: December 2020

Antimony oxide nanostructures have been identified as candidates for a range of electronic and optoelectronic applications. Here we demonstrate the growth of 2-dimensional antimony oxide nanostructures on various substrates, including highly oriented pyrolytic graphite (HOPG), MoS2 and α-Bi(110) nanoislands. Using scanning tunneling microscopy (STM) we show that the nanostructures formed are exclusively highly crystalline α-Sb2O3(111) monolayers with a lattice constant of 796 pm ± 7 pm. The nanostructures are triangular with lateral dimensions of up to ∼30 nm. Even though elemental antimony nanostructures are grown simultaneously mixed phases are not observed and both materials exhibit their own distinct growth modes. Moiré patterns are also observed and simulated, allowing confirmation of the atomic unit cell and an understanding of the orientation of the Sb2O3 structures with respect to the supporting materials. As in the bulk, the Sb2O3 nanostructures are formed from Sb4O6 molecules that are weakly interacting through van der Waals forces. This allows physical modification of the nanostructures with the STM tip. Scanning tunnelling spectroscopy reveals a wide band gap of at least 3.5 eV. Finally, we show that possible alternative structures that have unit cells comparable to those observed can be excluded based on our DFT calculations. The considered structures are a 2 × 2 reconstruction of β-Sb with one vacancy per unit cell and a van der Waals solid composed of Sb4 clusters. Previous reports have predominantly demonstrated Sb2O3 structures with much larger thicknesses.