bluuebunny/crossref_metadata_2025 huggingface dataset:
Gentherapie für Ataxien
Authors: Klockgether Thomas
Published: February 2023

Ataxien sind progredient verlaufende Krankheiten, die meist Folge einer
Degeneration des Kleinhirns sind. Ataxien werden in genetische, sporadisch
degenerative und erworbene (sekundäre) Formen unterteilt.
Während es bei den erworbene (sekundäre) Ataxien etablierte
Therapien gibt, sind genetische und sporadische degenerative Ataxien derzeit
nicht medizinisch behandelbar. Für diese Ataxien ist die Entwicklung
somatischer Gentherapien ein vielversprechender Weg. Ziele der Gentherapien bei
genetischen Ataxien sind die Inaktivierung schädlicher Gene durch
Gen-Silencing oder der Ersatz oder die Korrektur eines nicht
funktionsfähigen Gens. Eine weitere Option, die auch für
sporadisch degenerative Ataxien in Betracht kommt, sind Therapien, bei denen
neue oder modifizierte Gene transferiert werden. Bei den häufigeren
Ataxien, wie Friedreich-Ataxie, bestimmten spinozerebellären Ataxien und
Multisystematrophie werden aktiv Gentherapien entwickelt, und erste Phase
I-Studien werden bereits durchgeführt.
Feasibility of dose reduction for [18F]FDG-PET/MR imaging of patients with non-lesional epilepsy
Authors: Kertész Hunor , Traub-Weidinger Tatjana , Cal-Gonzalez Jacobo , Rausch Ivo , Muzik Otto , Shyiam Sundar Lalith Kumar , Beyer Thomas
Published: February 2023

The aim of the study was to evaluate the effect of reduced injected [18F]FDG activity levels on the quantitative and diagnostic accuracy of PET images of patients with non-lesional epilepsy (NLE).

Nine healthy volunteers and nine patients with NLE underwent 60-min dynamic list-mode (LM) scans on a fully-integrated PET/MRI system. Injected FDG activity levels were reduced virtually by randomly removing counts from the last 10-min of the LM data, so as to simulate the following activity levels: 50 %, 35 %, 20 %, and 10 % of the original activity. Four image reconstructions were evaluated: standard OSEM, OSEM with resolution recovery (PSF), the A-MAP, and the Asymmetrical Bowsher (AsymBowsher) algorithms. For the A-MAP algorithms, two weights were selected (low and high). Image contrast and noise levels were evaluated for all subjects while the lesion-to-background ratio (L/B) was only evaluated for patients. Patient images were scored by a Nuclear Medicine physician on a 5-point scale to assess clinical impression associated with the various reconstruction algorithms.

The image contrast and L/B ratio characterizing all four reconstruction algorithms were similar, except for reconstructions based on only 10 % of total counts. Based on clinical impression, images with diagnostic quality can be achieved with as low as 35 % of the standard injected activity. The selection of algorithms utilizing an anatomical prior did not provide a significant advantage for clinical readings, despite a small improvement in L/B (< 5 %) using the A-MAP and AsymBowsher reconstruction algorithms.

In patients with NLE who are undergoing [18F]FDG-PET/MR imaging, the injected [18F]FDG activity can be reduced to 35 % of the original dose levels without compromising.
Successful Treatment of a Painful Neuroma Using Fascicular Shifting in the Ulnar Nerve: A Case Report
Authors: Hruby Laura A. , Sporer Matthias E. , Krusche-Mandl Irena , Tereshenko Vlad , Platzgummer Hannes , Hajdu Stefan , Aszmann Oskar C.
Published: February 2023

Objective We report the case of a 40-year-old man with an inveterate ulnar nerve neuroma following a laceration injury of his left wrist twenty-three years ago. The patient presented with a typical ulnar claw-hand deformity and debilitating neuropathic pain in his hand (VAS 8.4). Pre-operative imaging revealed a neuroma of the ulnar nerve at the Guyon's canal. Moreover, a complete atrophy of all intrinsic hand muscles innervated by the ulnar nerve was present.

Methods A Zancolli lasso procedure was performed to reduce the clawing effect. The neuroma was resected producing a nerve defect of five centimeters. Since the injury dated back more than two decades and any motor recovery was deemed impossible at that point, the motor fascicle of the ulnar nerve, i.e. the deep branch, was selectively neurolysed and harvested as an autologous nerve graft. Then the graft was shifted into the defect to be coapted with the superficial branch fascicle in an end-to-end fashion.

Results The presented fascicular shift procedure resulted in satisfying and sustained pain reduction. At the six-month follow-up, the VAS decreased to 1.2, and two years post-operatively, the patient reported 2.5 on the VAS.

Conclusion The fascicular shift procedure offers an alternative approach to conventional nerve grafts. If nerve grafting is required, using a locally harvested graft avoids additional donor site morbidity. Assuming the clinical scenario allows for fascicular grafting, we strongly suggest considering the fascicular shift procedure as a cost-effective alternative to expensive conduits and processed nerve allografts in sensory nerve reconstruction.
Comparison of the hybrid and partial stent-in-stent method for endoscopic three-segment drainage for unresectable malignant hilar biliary obstruction
Authors: Yoshinari Motohiro , Hijioka Susumu , Nagashio Yoshikuni , Maruki Yuta , Ohba Akihiro , Kawasaki Yuki , Takeshita Kotaro , Morizane Chigusa , Tanaka Yasuhito , Okusaka Takuji
Published: February 2023

Background and study aims The clinical outcome of the new hybrid drainage method for unresectable malignant hilar biliary obstruction (UMHBO) has not yet been compared with that of the partial stent-in-stent (PSIS) method with three or more stents.

Patients and methods Patients with UMHBO underwent drainage of three segments using the hybrid or PSIS method. The clinical outcomes of both methods were compared retrospectively.

Results Overall, 54 patients underwent the hybrid (n = 31) or PSIS (n = 23) method of drainage with three or more stents for UMHBO. There were no significant differences in the technical success rate (hybrid vs. PSIS, 87.1 % vs. 87 %), clinical success rate according to per-protocol analysis (81.5 % vs. 70 %), early adverse events rate (14.8 % vs. 10%), late adverse events rate (7.4 % vs. 0 %), and technical success rate of the endoscopic transpapillary reintervention (90.9 % vs. 100 %). Time to recurrent biliary obstruction (TRBO) of the hybrid and PSIS methods was 178 and 231 days, respectively, with no significant difference (P = 0.354).

Conclusions The choice between the two methods should be made at the physician’s discretion.
Comparison of 6-mm and 10-mm-diameter, fully-covered, self-expandable metallic stents for distal malignant biliary obstruction
Authors: Harai Shota , Hijioka Susumu , Nagashio Yoshikuni , Ohba Akihiro , Maruki Yuta , Yamashige Daiki , Hisada Yuya , Yoshinari Motohiro , Kitamura Hidetoshi , Maehara Kosuke , Murashima Yumi , Kawasaki Yuki , Koga Takehiko , Takeshita Kotaro , Ueno Hideki , Kondo Shunsuke , Morizane Chigusa , Fukasawa Mitsuharu , Sone Miyuki , Saito Yutaka , Enomoto Nobuyuki , Okusaka Takuji
Published: February 2023

Background and study aims For distal malignant biliary obstruction, self-expandable metallic stents (SEMSs) have a larger inner diameter compared to plastic stents, which prolongs time to recurrent biliary obstruction (TRBO), although stent-related complications are still a problem. This study aimed to compare the outcomes between using 10– and 6-mm-diameter fully-covered SEMS (FCSEMS) for distal malignant biliary obstruction.

Patients and methods This single-center, retrospective study included patients with 10-mm or 6-mm-diameter FCSEMS to treat distal malignant biliary obstruction. Clinical success, stent-related adverse events (AEs), cumulative incidence of RBO, factors involved in stent-related AEs, and factors involved in RBO were evaluated.

Results There were 243 eligible cases between October 2017 and December 2021. The cumulative incidence of RBO did not differ significantly between the 10-mm and 6-mm groups. Stent-related AEs occurred in 31.6 % and 11.4 % of patients between the 10-mm and 6-mm groups, respectively (P < 0.01). Pancreatitis occurred in 10.5 % and 3.6 % (P = 0.04) and cholecystitis occurred in 11.8 % and 3.0 % of patients (P = 0.03) in the 10-mm and 6-mm groups, respectively. In multivariate analysis, the 6-mm stent was extracted as a factor linked to a reduced risk of AEs, but not as a risk factor of RBO.

Conclusions The 6-mm-diameter FCSEMS for distal malignant biliary obstruction is a well-balanced stent with a cumulative incidence of RBO compatible to that of the 10-mm-diameter FCSEMS and fewer stent-related AEs.
Differences in Tic Severity Among Adolescent Girls and Boys with Tourette Syndrome During the Pandemic
Authors: Larsh Travis R. , Wu Steve W. , Huddleston David A. , Lipps Tara D. , Gilbert Donald L.
Published: February 2023

Limited data are available regarding the impact of the coronavirus disease 2019 (COVID-19) pandemic on adolescents with Tourette syndrome (TS). We sought to compare sex differences in tic severity experienced by adolescents before and during the COVID-19 pandemic. We extracted from the electronic health record and retrospectively reviewed Yale Global Tic Severity Scores (YGTSS) from adolescents (ages 13 through 17) with TS presenting to our clinic before (36 months) and during (24 months) the pandemic. A total of 373 unique adolescent patient encounters (prepandemic: 199; pandemic: 173) were identified. Compared with prepandemic, girls accounted for a significantly greater proportion of visits during the pandemic (p < 0.001). Prepandemic, tic severity did not differ between girls and boys. During the pandemic, compared with girls, boys had less clinically severe tics (p = 0.003). During the pandemic, older girls, but not boys, had less clinically severe tics (ρ =− 0.32, p = 0.003). These findings provide evidence that, regarding tic severity assessed with YGTSS, the experiences of adolescent girls and boys with TS have differed during the pandemic.
Enantioselective [2,3]-Wittig Rearrangement of Carboxylic Acid Derived Enolates by Tetradentate Chiral Lithium Amide
Authors: Shirai Ryuichi , Yatsuzuka Kenji , Kawasaki Midori
Published: February 2023

A chiral lithium amide mediated enantioselective [2,3]-Wittig rearrangement of carboxylic acid enolate has been developed. The reaction proceeds through the formation of a chiral mixed aggregate that shields one enantioface of enolate anion to give a highly functionalized chiral α-hydroxycarboxylic acid.
Comparative Study of DIEP and PAP Flaps in Breast Reconstruction: Reconstructive Outcomes and Fat Necrosis
Authors: Kim Hyung Bae , Han Seong John , Kim Eon Key , Eom Jin Sup , Han Hyun Ho
Published: February 2023

Background This study compared the reconstructive outcomes and fat necrosis of the profunda artery perforator (PAP) flap with those of the deep inferior epigastric perforator (DIEP) flap.

Methods Data on all DIEP and PAP flap breast reconstructions performed between 2018 and 2021 at Asan Medical Center were compared. The overall reconstructive outcomes and presence of fat necrosis were analyzed through ultrasound evaluation performed by a board-certified radiologist.

Results The PAP (n = 43) and DIEP flaps (n = 99) were used to reconstruct 31 and 99 breasts, respectively. The average age of the patients in the PAP flap group (39.1 ± 7.3 years) was lower than in the DIEP flap group (47.4 ± 7.7 years), and the body mass index (BMI) of patients undergoing PAP flap reconstruction (22.7 ± 2.8 kg/m2) was lower than those undergoing DIEP flap reconstruction (24.3 ± 3.4 kg/m2). There was no total loss of both flaps. Donor site morbidity was higher in the PAP flap group (11.1%) compared with the DIEP flap (1.0%). The rate of fat necrosis was higher in the PAP flaps (40.7%) than in the DIEP flaps (17.8%) during ultrasound.

Conclusion In our study, we found that PAP flap reconstruction tended to be performed in patients who were younger with lower BMIs compared with the DIEP flap. Successful reconstructive outcomes were observed in both the PAP and DIEP flaps; however, a higher rate of necrosis was observed in the PAP flap compared with the DIEP flap.
The Cesarean Scar of Pregnancy: Ultrasound Findings and Expectant Management Outcomes
Authors: Spong Catherine Y. , Yule Casey S. , Fleming Elaine T. , Lafferty Ashlyn K. , McIntire Donald D. , Twickler Diane M.
Published: February 2023

Objective The nomenclature has evolved from low implantation to cesarean scar pregnancy (CSP) and criteria are recommended for identification and management. Management guidelines include pregnancy termination due to life-threatening complications. This article applies ultrasound (US) parameters recommended by the Society for Maternal Fetal Medicine (SMFM) in women who were expectantly managed.

Study Design Pregnancies were identified between March 1, 2013 and December 31, 2020. Inclusion criteria were women with CSP or low implantation identified on US. Studies were reviewed for niche, smallest myometrial thickness (SMT), and location of basalis blinded to clinical data. Clinical outcomes, pregnancy outcome, need for intervention, hysterectomy, transfusion, pathologic findings, and morbidities were obtained by chart review.

Results Of 101 pregnancies with low implantation, 43 met the SMFM criteria at < 10 weeks and 28 at 10 to 14 weeks. At < 10 weeks, SMFM criteria identified 45out of 76 women; of these 13 required hysterectomy; there were 6 who required hysterectomy but did not meet the SMFM criteria. At 10 to < 14 weeks, SMFM criteria identified 28 out of 42 women; of these 15 required hysterectomy. US parameters yielded significant differences in women requiring hysterectomy, at < 10 weeks and 10 to < 14 weeks' gestational age epochs, but the sensitivity, specificity, positive (PPV), and negative predictive values (NPV) of these US parameters have limitations in identifying invasion to determine management. Of the 101 pregnancies, 46 (46%) failed < 20 weeks, 16 (35%) required medical/surgical management including 6 hysterectomies, and 30 (65%) required no intervention. There were 55 pregnancies (55%) that progressed beyond 20 weeks. Of these, 16 required hysterectomy (29%) while 39 (71%) did not. In the overall cohort of 101, 22 (21.8%) required hysterectomy and an additional16 (15.8%) required some type of intervention, while 66.7% required no intervention.

Conclusion SMFM US criteria for CSP have limitations for discerning clinical management due to lack of discriminatory threshold.

Key Points
Effects of Bout Duration on Load, Sprint, and Jump Ability During a
One-on-one Transition Task
Authors: Asian-Clemente Jose , Rabano-Munoz Alberto , Requena Bernardo , Suarez-Arrones Luis
Published: February 2023

This study examined the training load on professional soccer players during
transition games performed with different bout durations and their effects on
speed and jump tests. Fourteen young soccer players played a transition game of
different bout durations: 15 (TG15), 30 (TG30), and 60
(TG60) seconds. Total distance covered (DC), accelerations and
decelerations above 1.0 and 2.5 m·s-2, rate of
perceived exertion (RPE), maximal heart rate (HRmax) and above
90% (HR>90), distance covered between
18.0–20.9 km·h-1 (DC
18.0–20.9 km·h-1),
21.0–23.9 km·h-1 (DC
21.0–23.9 km·h-1), above
24.0 km·h-1
(DC>24.0 km·h-1), peak speed, sprint
profile, sprint, and countermovement jump tests were recorded. TG15
obtained greater DC, DC>21.0 km·h-1, Player
load, Acc>2.5 m·s-2 than TG30 and
TG60 (p<0.01) and
Acc<2.5 m·s-2,
Dec>2.5 m·s-2 than TG60
(p<0.01). TG30 showed more
HR>90 and RPE (p<0.01) than
TG15, and DC, DC>18.0 km·h-1,
Player load, Acc>2.5 m·s-2,
Dec>2.5 m·s-2, HR>90
and RPE than TG60 (p<0.01 and<0.05).
Transition games showed lower sprint and jump results after the intervention
(p<0.01). Bout duration has been configured as an important
constraint that influences the transition games and the performance of soccer
players.
What dictates income in New York City? SHAP analysis of income estimation based on Socio-economic and Spatial Information Gaussian Processes (SSIG)
Authors: Bai Ruiqiao , Lam Jacqueline C. K. , Li Victor O. K.
Published: February 2023

Income inequality presents a key challenge to urban sustainability across the developed economies. Traditionally, accurate high granularity income data are generally obtained from field surveys. However, due to privacy considerations, field subjects are hesitant to provide accurate personal income data. A Socio-economic & Spatial-Information-GP (SSIG) model is thereby developed to estimate district-based high granularity income for New York City (NYC). As compared to the state-of-the-art Gaussian Processes (GP) income estimation model based entirely on spatial information, SSIG incorporates socio-economic domain-specific knowledge into a GP model. For SSIG to be explainable, SHapley Additive exPlanations (SHAP) analysis is undertaken to evaluate the relative contribution of various key individual socio-economic variables to district-based per-capita and median household income in NYC. Differentiating from traditional income inequality studies based predominantly on linear or log-linear regression model, SSIG presents a novel income-based model architecture, capable of modelling complex non-linear relationships. In parallel, SHAP analysis serves an effective analytical tool for identifying the key attributes to income inequality. Results have shown that SSIG surpasses other state-of-the-art baselines in estimation accuracy, as far as per-capita and median household income estimation at the Tract-level and the ZIP-level in NYC are concerned. SHAP results have indicated that having a bachelor or a postgraduate degree can accurately predict income in NYC, despite that between-district income inequality due to Sex/Race remains prevalent. SHAP has further confirmed that between-district income gap is more associated with Race than Sex. Furthermore, ablation study shows that socio-economic information is more predictive of income at the ZIP-level, relative to the spatial information. This study carries significant implications for policy-making in a developed context. To promote urban economic sustainability in NYC, policymakers can attend to the growing income disparity (income inequality) contributed by Sex and Race, while giving more higher education opportunities to residents in the lower-income districts, as the estimated per-capita income is more sensitive to the proportion of adults ≥25 holding a bachelor’s degree. Finally, interpretative SHAP analysis is useful for investigating the relative contribution of socio-economic inputs to any predicted outputs in future machine-learning-driven socio-economic analyses.
In search of a Rohingya digital diaspora: virtual togetherness, collective identities and political mobilisation
Authors: Ansar Anas , Khaled Abu Faisal Md.
Published: February 2023

Frequently called the most persecuted minority in the world, the Rohingyas have suffered systematic violence and oppression in Myanmar since the 1970s. Today, the vast majority of the nearly three million Rohingyas are in exile, escaping state-sponsored human rights violations and persecution in the Rakhine state of Myanmar—a place they call “home”. Neighbouring Bangladesh, which currently hosts over a million displaced Rohingya, has been a ‘sanctuary’ for at least the last four decades. A sizable community has also emerged successively in other South-East Asian countries and pockets of Australia, Europe and North America. In this context, bringing together issues at the crossroads of (im)mobilities, online connectivity and the quest for identity, this study examines the role of social media platforms in forming and shaping new types of diaspora activism among the exiled Rohingyas. Drawing on yearlong online ethnographic findings, it unpacks how digital platforms constitute a space for togetherness, where diasporic Rohingya identities are constructed, contested and mediated. Analysing recurring themes and patterns of engagement on these web-based platforms, the paper looks at how diasporic civic and political e-activisms are transforming the very contours of Rohingya identity formation and their pursuit of recognition. Finally, focusing on such a creative constellation of socio-cultural and political issues in virtual space, we demonstrate how Rohingyas practice a politics of resistance and recognition when confronting the policy pretensions of Myanmar’s government.
Precession laser optimized for micro-drilling on aerospace material
Authors: Shapiro Maura
Published: February 2023

Parameters identified to reduce and eliminate micro-hole sidewall tapering in nickel alloy C263.
Effects of hydrogen bonds on two-photon absorption of Green fluorescent protein chromophore analogue
Authors: Zhang Wenying , Geng Minghui , Ma Xuexue , Zhao Ke
Published: February 2023

Effects of hydrogen bonds on two-photon absorption (TPA) of a new donor-acceptor type green fluorescent protein chromophore analogue are investigated by employing a combined molecular dynamics and quantum chemistry method. The probable configurations of the chromophore in water are extracted from molecular dynamics simulation and the TP A properties of more than twenty hydrogen bond complexes are computed by quadratic response theory. Thereby, the structure and property relations are established. Three types of hydrogen bonds including O⋯H–O, N–H⋯O and N⋯H–O can be formed between the chromophore and water molecules. The O⋯H–O induces a little decrease of TPA cross section with a red-shifted wavelength. The N–H⋯O gives rise to a great enhancement of TP A at a longer wavelength, while the N⋯H–O decreases TP A significantly and makes the wavelength blue-shifted. The reasons for these effects are rationalized well by using a two-state model analysis. The related molecular orbitals are also plotted to visualize the charge transfer characters. In addition, the averaged TP A spectrum is obtained by calculating the probabilities of various hydrogen bond complexes. Our research could provide a good insight into the design of two-photon materials by making use of hydrogen bond networks.
A review of electrochemical glucose sensing based on transition metal phosphides
Authors: Lakshmy Seetha , Santhosh Shilpa , Kalarikkal Nandakumar , Rout Chandra Sekhar , Chakraborthy Brahmananda
Published: February 2023

The alarming situation of the growing number of diabetic patients has called for a simple, sensitive, and selective glucose sensor that is also stable and user-friendly. In this report, we have reviewed the latest electrochemical sensing technology based on transition metal phosphides (TMPs) for glucose detection. Apart from the oxides, sulfides, nitrides, chalcogenides, etc., transition metal phosphides are less explored and have emerged as potential candidates for non-enzymatic glucose sensing applications. This review will help scientists and researchers to exploit relevant properties for glucose sensing applications, identify the best synthesis approaches to prepare transition metal phosphides, and provide information on the factors influencing glucose sensing and parameters to improve the performance and theoretical insights into the mechanism involved. Therefore, this review emphasizes a few methods adopted for tuning the properties of TMPs to achieve a stable glucose-sensing device. Finally, we propose our perspectives on potential directions for TMP-based material development in enzymeless electrochemical glucose sensing applications.
Positive impurity size effect in degenerate Sn-doped GaN prepared by pulsed sputtering
Authors: Nishikawa Yuto , Ueno Kohei , Kobayashi Atsushi , Fujioka Hiroshi
Published: February 2023

This study reports on the epitaxial growth of heavily Sn-doped GaN films by pulsed sputtering deposition (PSD) and their basic characteristics, which include electrical, optical, and structural properties. Heavily Sn-doped GaN yielded a maximum electron concentration of 2.0 × 1020 cm−3 while keeping an atomically flat surface. The high electron concentration was confirmed by Raman spectroscopy measurements. X-ray diffraction analysis revealed that the Sn dopants exhibited a positive-size effect coefficient, which is opposite to conventional n-type dopants, such as Si and Ge. Furthermore, the shifts toward higher energy of optical bandgap energies and near-band edge emission peaks clearly indicated the highly degenerated nature of the PSD-grown Sn-doped GaN. These results indicate that the introduction of Sn atoms is quite promising for stress control in n-type GaN.
Compact multimode silicon racetrack resonators for high-efficiency tunable Raman lasers
Authors: Zhang Yaojing , Zhong Keyi , Tsang Hon Ki
Published: February 2023

Multimode integrated waveguides have large fabrication tolerances and enable low propagation losses. Multimode waveguide bends have, therefore, been used for high-quality (Q) factor multimode resonators. Conventional multimode circular bends typically require large bend radii to avoid the excitation of the higher-order modes. In this paper, we make use of multimode adiabatic bends in a multimode silicon racetrack resonator with a compact footprint of 0.16 mm2. The adiabatic bends help suppress the higher-order modes. The Q factor of the racetrack resonator has an average value of 2.2 × 106 in the wavelength range of 1260–1480 nm. Benefiting from the broadband high-Q multimode racetrack resonator, we experimentally demonstrated a continuous-wave Raman laser with a widely tunable wavelength range of 157 nm. The Raman laser has a threshold power of 0.2 mW and one of the highest slope efficiencies of 27.5%. This work shows how a high-efficiency integrated Raman laser can be achieved with a wide tunable wavelength range, compact footprint, and low threshold power for a tunable source that can extend the output wavelength beyond the direct output range of the pump laser.
A fermi acceleration model to study the electron acceleration in laser-produced plasma with localized structures formation and turbulence generation
Authors: Singh Indraj , Uma R. , Sharma R. P.
Published: February 2023

This investigation presents a model based on the nonlinear coupling of waves for studying electron acceleration in laser-produced plasma. The impact of the localized structures formation and turbulence generation on electron acceleration is investigated via a second-order Fermi acceleration mechanism. For this purpose, the dynamical coupled equations of the extraordinary mode laser and the upper hybrid wave are formulated by taking into account relativistic and ponderomotive nonlinearity. These coupled equations are solved by laboratory simulations using pseudo-spectral and finite difference methods. The simulation results show the turbulent wavenumber spectrum associated with the localization of the laser beam. The power-law scaling of turbulence generation has been utilized to study the formation of the thermal tail of energetic electrons, which may be responsible for the acceleration of the electrons. A fractional diffusion method has been exploited to determine electron acceleration. This study also provides a simplified model for a better understanding of the nonlinear progression of the laser beam during propagation inside the magnetized plasma.
Active Brownian particles in random and porous environments
Authors: Moore Fergus , Russo John , Liverpool Tanniemola B. , Royall C. Patrick
Published: February 2023

The transport of active particles may occur in complex environments, in which it emerges from the interplay between the mobility of the active components and the quenched disorder of the environment. Here, we explore the structural and dynamical properties of active Brownian particles (ABPs) in random environments composed of fixed obstacles in three dimensions. We consider different arrangements of the obstacles. In particular, we consider two particular situations corresponding to experimentally realizable settings. First, we model pinning particles in (non-overlapping) random positions and, second, in a percolating gel structure and provide an extensive characterization of the structure and dynamics of ABPs in these complex environments. We find that the confinement increases the heterogeneity of the dynamics, with new populations of absorbed and localized particles appearing close to the obstacles. This heterogeneity has a profound impact on the motility induced phase separation exhibited by the particles at high activity, ranging from nucleation and growth in random disorder to a complex phase separation in porous environments.
Equation-of-state-constrained pressure dependence of x-ray elastic constants of gold for stress components calculation in a high-pressure anvil apparatus
Authors: Lin Lin , Ma Yanzhang
Published: February 2023

In the resolution of the large divergence between pressure calculated by way of axial stress components from elastic constants and pressure determined by an equation of state, a 2nd order pressure dependency of elastic constants is introduced. Incorporating results from the equation of state and ultrasonic measurements in the literature, we determined the pressure dependency of x-ray elastic constants of gold and established functions for the calculation of macro-stress components from its macro-strain counterparts. The precision of stress components through these functions is estimated to be at 1% level. The determination of stress components, including crucial shear components, through analysis of an x-ray diffraction image, is demonstrated.
Influence of edge plasma turbulence on the low-threshold parametric decay instability at ECRH
Authors: Tretinnikov P. V. , Popov A. Yu. , Gusakov E. Z. , Heuraux S.
Published: February 2023

The saturation level of the two Upper-Hybrid-plasmon low-threshold parametric decay instability (PDI) depends on the pump wave beam width. The edge plasma turbulence may lead to drastic distortion of the pump beam, thus generating PDI characteristic changes. Numerical evaluations of the PDI process are provided in this work for different turbulence scenarios. The average PDI characteristics are evaluated and compared to the simulation results for the pump beam unperturbed by the edge plasma turbulence. It is shown that up to the intermediate turbulence level, the PDI characteristics are only gently modified. But at high edge turbulence level, which can happen in tokamaks, the threshold increases and the growth rate reduces. It is important to note that the anomalous absorption keeps a little reduction value, whatever the edge turbulence regimes.
Adaptive aberration correction using an electrowetting array
Authors: Zohrabi Mo , Lim Wei Yang , Gilinsky Samuel , Bright Victor M. , Gopinath Juliet T.
Published: February 2023

We demonstrate a method that permits wavefront aberration correction using an array of electrowetting prisms. A fixed high fill factor microlens array followed by a lower fill factor adaptive electrowetting prism array is used to correct wavefront aberration. The design and simulation of such aberration correction mechanism is described. Our results show significant improvement to the Strehl ratio by using our aberration correction scheme which results in diffraction limited performance. Compactness and effectiveness of our design can be implemented in many applications that require aberration correction, such as microscopy and consumer electronics.
Thermally induced surface faceting on heteroepitaxial layers
Authors: Zhang Yiwen , Zhou Chuan , Zhu Ying , Xia Guangrui (Maggie) , Li Lei , Wen Rui-Tao
Published: February 2023

Heteroepitaxial semiconductors such as Ge-on-Si are widely used in current opto-electronic and electronic applications, and one of the most important challenges for epitaxial Ge-on-Si is threading dislocations (TDs) in Ge layers caused by lattice mismatch between Ge and Si. Here, apart from traditional wet chemical etching, we report a convenient approach to evaluate the threading dislocation densities in heteroepitaxial layers through vacuum thermal annealing. More importantly, the controversial origin of thermal annealing induced pits on a Ge surface was addressed in this work. By combining both experiments and density functional theory (DFT) calculations, we find that the {111} facets defined thermal pits on Ge (001) surfaces are mainly caused by threading dislocation activation. Ge adatoms at the TD segments sublimate preferentially than the ones on dislocation-free Ge (001) surface regions, and its further evolution is determined by surface energies of {111} facets, leading to a construction of inverted pyramid-shaped thermal pits.
Non-monotonic radial structures of fluctuating temperatures and densities associated with fishbone activities in KSTAR
Authors: Lee Wonjun , Kim Jaewook , Joung Semin , Choi G. J. , Kim J. , Woo M. , Rhee T. , Lee K. D. , Bak J. G. , Kang J. S. , Ghim Y.-C.
Published: February 2023

General characteristics of a fishbone mode in KSTAR are investigated. Fishbone activities are observed with a Mirnov coil, an electron cyclotron emission radiometer (from the core to the edge of plasmas) and an beam emission spectroscopy system (core or edge plasmas) which are measuring fluctuations of poloidal magnetic fields, electron temperatures, and densities, respectively. Temporal evolutions of these fluctuations are similar to the observations from other tokamaks. An interesting and notable feature found in KSTAR fishbone modes is that radial coherence structures of electron temperature and density with respect to magnetic fluctuations are non-monotonic that they have a local minimum at r/a∼0.7 and a maximum at r/a∼0.9 in addition to the usual global peak near the q = 1 surface, where r/a is the normalized minor radius and q is the safety factor. Furthermore, the associated temporal evolution of the electron temperatures in slow-time scale, i.e., less than 1 kHz, with the fishbone activities show that there exist a drop in temperature or increase in temperature depending on inside or outside the q = 1 surface, respectively, from the core to the edge plasmas except that there are almost no temperature changes in the intermediate region which seems to be correlated with the non-monotonic coherence profile. Such a non-monotonic structure and the slow temporal evolution of temperatures are explained with barely trapped resonating fast ions with the banana orbit widths of the order of the minor radius, so that they transit the core and the edge regions simultaneously without trespassing the mid-plane intermediate region.
Bouncing droplets on micro-grooved non-wetting surfaces
Authors: Wang Shi-Zheng , Huang Xianfu , Chen Longquan , Yu Ying-Song
Published: February 2023

Water droplets impinging on micro-grooved polydimethylsiloxane surfaces were studied. Depending on the impact velocity and surface roughness, different phenomena such as no bouncing, complete rebound (CR), bouncing occurring with droplet breakup (BDB), partial rebound, and sticky state were observed. The lower limit of impact velocity for bouncing droplets can be determined by balancing the kinetic energy of the droplet with energy barrier due to contact angle hysteresis. To predict the upper limit of impact velocity for bouncing droplets, a high-speed camera was used to record droplet impact at an ultrahigh speed and it was found that the transition from CR to BDB was attributed to a local wetting transition from the Cassie–Baxter state to the Wenzel state. Based on the experimental observation, a theoretical model was developed to predict the upper limit of impact velocity taking into account the penetration of the liquid into the micro-grooves. In addition, there was a shorter contact time of bouncing droplets with the decrease in the Weber number and surface roughness has a small influence on the contact time in our experiments.
Tuning the interlayer microstructure and residual stress of buffer-free direct bonding GaN/Si heterostructures
Authors: Zhou Yan , Zhou Shi , Wan Shun , Zou Bo , Feng Yuxia , Mei Rui , Wu Heng , Shigekawa Naoteru , Liang Jianbo , Tan Pingheng , Kuball Martin
Published: February 2023

The direct integration of GaN with Si can boost great potential for low-cost, large-scale, and high-power device applications. However, it is still challengeable to directly grow GaN on Si without using thick strain relief buffer layers due to their large lattice and thermal-expansion-coefficient mismatches. In this work, a GaN/Si heterointerface without any buffer layer is fabricated at room temperature via surface activated bonding (SAB). The residual stress states and interfacial microstructures of GaN/Si heterostructures were systematically investigated through micro-Raman spectroscopy and transmission electron microscopy. Compared to the large compressive stress that existed in GaN layers grown on Si by metalorganic chemical vapor deposition, a significantly relaxed and uniform small tensile stress was observed in GaN layers bonded to Si by SAB; this is mainly ascribed to the amorphous layer formed at the bonding interface. In addition, the interfacial microstructure and stress states of bonded GaN/Si heterointerfaces was found to be significantly tuned by appropriate thermal annealing. With increasing annealing temperature, the amorphous interlayer formed at the as-bonded interface gradually transforms into a thin crystallized interlayer without any observable defects even after annealing at 1000 °C, while the interlayer stresses at both GaN layer and Si monotonically change due to the interfacial re-crystallization. This work moves an important step forward directly integrating GaN to the present Si CMOS technology with high quality thin interfaces and brings great promises for wafer-scale low-cost fabrication of GaN electronics.
Generation of bright collimated vortex
γ
-ray via laser driven cone-fan target
Authors: Zhang Cui-Wen , Bake Mamat-Ali , Xiao Hong , Sang Hai-Bo , Xie Bai-Song
Published: February 2023

We use numerical simulations to demonstrate that a source of bright collimated vortex γ-ray with large orbital angular momentum and small divergence can be achieved by irradiating an intense circularly polarized laser on a cone-fan target. In the all-optical setup, electron beam of energy with hundreds of MeV and also vortex laser pulse are formed. A considerable fraction of angular momentum of laser is converted to electron beam and furthermore to final vortex γ-ray, which are roughly 27.8% and 3%, respectively. The conversion efficiency of energy from laser to them is around 41% and 3.8%. Moreover, comparative simulations for different inner sizes of the cone reveal that there exists an optimal size making the highest angular momentum of γ-ray photons. For simulations with different laser modes, the circularly polarized laser is more appropriate rather than the Laguerre–Gaussian one to generate vortex γ-ray.
Nitrogen in silicon for room temperature single-electron tunneling devices
Authors: Yadav Pooja , Arora Hemant , Samanta Arup
Published: February 2023

Single-electron transistor (SET) has an advanced feature that can be exploited in quantum devices. For practical utilization of such devices, the room-temperature operation is highly essential. Dopant-based single-electron devices are well studied at low temperatures although a few devices are developed for high-temperature operation with certain limitations. Here, we propose and theoretically exhibit that nitrogen (N) donor in silicon is an important candidate for the effective designing of quantum devices. Theoretical calculation of the density of states using the semi-empirical density functional theory method indicates that N-donor in silicon has a deep ground state compared to a phosphorus (P) donor. The N-donor spectrum is explored in nano-silicon structure along with the P-donor. A comparative study of the Bohr radius of N-donor and P-donor is also reported. The simulated current–voltage characteristics confirm that the N-doped device is better suited for SET operation at room temperature.
Decomposition behavior and thermoelectric properties of copper selenide—graphite composites
Authors: Staab Lennart , Kötzsch Torsten , Noack Tom Jonathan , Oeckler Oliver
Published: February 2023

Cu2Se is a high ZT material consisting of cheap and earth abundant elements. Its high thermoelectric performance is mainly based on very low thermal conductivity associated with mobile atoms. This comes with the drawback of a critical voltage, over which the material decomposes to elemental copper and a copper-deficient Cu2−xSe phase. Composites of copper selenide with graphite do not enhance the critical voltage significantly as copper selenide is not completely encapsulated by graphite. Thermoelectric properties of pellets of such composites obtained by mixing and pressing Cu2Se powder and graphite flakes are comparable to pristine Cu2Se, but thermal stability increases remarkably. Samples with different grain sizes show that the reproducibility of measurements is worse for larger grains, which in addition lead to inferior thermoelectric performance. Higher graphite contents increase both thermal and electrical conductivity, and an optimum of the thermoelectric figure of merit ZT is observed for fine-grained samples with 4 wt. % graphite.
Asymmetric acoustic metagrating enabled by parity-time symmetry
Authors: Quan Jiaqi , Gao Lei , Jiang Jian-Hua , Xu Yadong
Published: February 2023

Passive parity-time (PT) symmetric metamaterials as a fundamental carrier to investigate non-Hermitian systems have attracted significant interest, but previous studies have rarely focused on the diffraction properties of the PT system, especially the diffraction effect in the metasurfaces with phase gradient modulation. Here, by merging two concepts of phase gradient and PT symmetry together, we design and study a non-Hermitian acoustic gradient metasurface (i.e., metagrating). We show that the PT symmetry breaks spatially the symmetry of reflected wave diffraction in the acoustic metagrating, making it an asymmetric mirror. In particular, at the PT-ensured exceptional point, for incident waves from one side, such metagrating behaves as a phase gradient metasurface, in which high-efficiency retroreflection governed generalized Snell's law occurs. For an incident wave from the opposite direction, such a metagrating is a common grating, whose diffraction in the reflection follows the common diffraction equation. Our work builds a bridge connecting the phase gradient and passive PT symmetric system, enriching the methods for wavefront manipulation and exhibiting potential applications in the design of multifunctional acoustic devices.
Magnetic properties versus interface density in rigid-exchange-coupled amorphous multilayers with induced uniaxial anisotropy
Authors: Rani Parul , Jönsson Petra E. , Ghorai Sagar , N’Diaye Alpha T. , Andersson Gabriella
Published: February 2023

We demonstrate the possibility to tune the saturation magnetization, coercivity, and uniaxial in-plane anisotropy constant in amorphous bilayers and multilayers of Co85(Al70Zr30)15 and Sm11Co82Ti7 through the interface density. From magnetometry and x-ray circular dichroism (XMCD) measurements, we conclude that the easy-axis coercivity μ0Hc increases four times when the number of bilayer repetitions, N, increases from 1 to 10 within a constant total sample thickness of 20 nm. At the same time, the anisotropy constant Ku also increases by a factor four, whereas the saturation magnetization Ms decreases slightly. The Co spin and orbital moments, ms and ml, are found to be approximately constant within the sample series. The average total Co moment is only 0.8–0.9 μB/atom, but the ml/ms ratio is strongly enhanced compared to pure Co. Magnetization curves extracted from XMCD measurements show that the Co and Sm moments are ferromagnetically coupled for all samples.
Vertical-MXene based micro-supercapacitors with thickness-independent capacitance
Authors: Huang Haichao , Xie Yanting , Xiong Da , Chen Ningjun , Chu Xiang , Jiang Xinglin , Zhang Haitao , Yang Weiqing
Published: February 2023

MXenes have shown great potential as an emerging two-dimensional (2D) material for micro-supercapacitors (MSCs) due to their high conductivity, rich surface chemistry, and high capacity. However, MXene sheets inherently tend to lay flat on the substrate during film formation to assemble into compact stacked structures, which hinders ion accessibility and prolongs ion transport paths, leading to highly dependent electrochemical properties on the thickness of the film. Here, we demonstrate a vertically aligned Ti3C2Tx MXene based micro-supercapacitor with an excellent electrochemical performance by a liquid nitrogen-assisted freeze-drying method. The vertical arrangement of the 2D MXene sheets allows for directional ion transport, enabling the vertical-MXene based MSCs to exhibit thickness-independent electrochemical properties even in thick films. In addition, the MSCs displayed a high areal capacitance of 87 mF cm−2 at 10 mV s−1 along with an excellent stability of ∼87.4% after 10 000 charge–discharge cycles. Furthermore, the vertical-MXene approach proposed here is scalable and can be extended to other systems involving directional transport.
Dynamics of the spin-boson model: The effect of bath initial conditions
Authors: Chen Lipeng , Yan Yiying , Gelin Maxim F. , Lü Zhiguo
Published: February 2023

The dynamics of the (sub-)Ohmic spin-boson model under various bath initial conditions is investigated by employing the Dirac–Frenkel time-dependent variational approach with the multiple Davydov D1 Ansatz in the interaction picture. The validity of our approach is carefully checked by comparing the results with those of the hierarchy equations of motion method. By analyzing the features of nonequilibrium dynamics, we identify the phase diagrams for different bath initial conditions. We find that for the spectral exponent s < sc, there exists a transition from coherent to quasicoherent dynamics with increasing coupling strengths. For sc < s ≤ 1, the coherent to incoherent crossover occurs at a certain coupling strength and the quasicoherent dynamics emerges at much larger couplings. The initial preparation of the bath has a considerable influence on the dynamics.
Two-photon magneto-optical transitions in quantum rings
Authors: Phuc Huynh V.
Published: February 2023

We study the effect of the magnetic and Aharonov–Bohm (AB) flux fields on the two-photon absorption (2PA) in a quantum ring (QR) system. The expression of 2PA coefficient is expressed through the two-photon transition probability including both intraband and interband transitions. The effect of the polarization orientation of the incident light breaks the symmetry from the contribution between the AB flux field and the azimuthal quantum number. Magnetic and AB flux fields have a significant effect on the electronic properties of the QR. The 2PA spectra for intraband transitions are in the THz range and have a much higher magnitude compared to those for interband transitions, which are located in the near-infrared range. The increase in the magnetic field results in a blue-shift of the 2PA spectra for both intraband and interband transitions, whereas changes in the azimuthal quantum number only affect the spectra for interband transitions.