bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparative analysis of batch correction methods for FDG PET/CT using metabolic radiogenomic data of lung cancer patients
Authors: Lee Hyunjong , Seo Sujin , Won Sungho , Park Woong-Yang , Choi Joon Young , Lee Kyung-Han , Lee Se-Hoon , Moon Seung Hwan
Published: October 2023

In radiomics research, the issue of different instruments being used is significant. In this study, we compared three correction methods to reduce the batch effects in radiogenomic data from fluorodeoxyglucose (FDG) PET/CT images of lung cancer patients. Texture features of the FDG PET/CT images and genomic data were retrospectively obtained. The features were corrected with different methods: phantom correction, ComBat method, and Limma method. Batch effects were estimated using three analytic tools: principal component analysis (PCA), the k-nearest neighbor batch effect test (kBET), and the silhouette score. Finally, the associations of features and gene mutations were compared between each correction method. Although the kBET rejection rate and silhouette score were lower in the phantom-corrected data than in the uncorrected data, a PCA plot showed a similar variance. ComBat and Limma methods provided correction with low batch effects, and there was no significant difference in the results of the two methods. In ComBat- and Limma-corrected data, more texture features exhibited a significant association with the TP53 mutation than in those in the phantom-corrected data. This study suggests that correction with ComBat or Limma methods can be more effective or equally as effective as the phantom method in reducing batch effects.
Augmentation strategies for an imbalanced learning problem on a novel COVID-19 severity dataset
Authors: Schaudt Daniel , von Schwerin Reinhold , Hafner Alexander , Riedel Pascal , Reichert Manfred , von Schwerin Marianne , Beer Meinrad , Kloth Christopher
Published: October 2023

Since the beginning of the COVID-19 pandemic, many different machine learning models have been developed to detect and verify COVID-19 pneumonia based on chest X-ray images. Although promising, binary models have only limited implications for medical treatment, whereas the prediction of disease severity suggests more suitable and specific treatment options. In this study, we publish severity scores for the 2358 COVID-19 positive images in the COVIDx8B dataset, creating one of the largest collections of publicly available COVID-19 severity data. Furthermore, we train and evaluate deep learning models on the newly created dataset to provide a first benchmark for the severity classification task. One of the main challenges of this dataset is the skewed class distribution, resulting in undesirable model performance for the most severe cases. We therefore propose and examine different augmentation strategies, specifically targeting majority and minority classes. Our augmentation strategies show significant improvements in precision and recall values for the rare and most severe cases. While the models might not yet fulfill medical requirements, they serve as an appropriate starting point for further research with the proposed dataset to optimize clinical resource allocation and treatment.
Age and severity-dependent gut microbiota alterations in Tunisian children with autism spectrum disorder
Authors: Chamtouri Mariem , Gaddour Naoufel , Merghni Abderrahmen , Mastouri Maha , Arboleya Silvia , de los Reyes-Gavilán Clara G.
Published: October 2023

Alterations in gut microbiota and short chain fatty acids (SCFA) have been reported in autism spectrum disorder (ASD). We analysed the gut microbiota and fecal SCFA in Tunisian autistic children from 4 to 10 years, and results were compared to those obtained from a group of siblings (SIB) and children from the general population (GP). ASD patients presented different gut microbiota profiles compared to SIB and GP, with differences in the levels ofBifidobacteriumandCollinsellaoccurring in younger children (4–7 years) and that tend to be attenuated at older ages (8–10 years). The lower abundance ofBifidobacteriumis the key feature of the microbiota composition associated with severe autism. ASD patients presented significantly higher levels of propionic and valeric acids than GP at 4–7 years, but these differences disappeared at 8–10 years. To the best of our knowledge, this is the first study on the gut microbiota profile of Tunisian autistic children using a metataxonomic approach. This exploratory study reveals more pronounced gut microbiota alterations at early than at advanced ages in ASD. Although we did not account for multiple testing, our findings suggest that early interventions might mitigate gut disorders and cognitive and neurodevelopment impairment associated to ASD.
The angiotensin-converting enzyme I/D polymorphism does not impact training-induced adaptations in exercise capacity in patients with stable coronary artery disease
Authors: Sjúrðarson Tórur , Kristiansen Jacobina , Nordsborg Nikolai B. , Gregersen Noomi O. , Lydersen Leivur N. , Grove Erik L. , Kristensen Steen D. , Hvas Anne-Mette , Mohr Magni
Published: October 2023

Systematic exercise training effectively improves exercise capacity in patients with coronary artery disease (CAD), but the magnitude of improvements is highly heterogeneous. We investigated whether this heterogeneity in exercise capacity gains is influenced by the insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme (ACE) gene. Patients with CAD (n = 169) were randomly assigned to 12 weeks of exercise training or standard care, and 142 patients completed the study. The ACE polymorphism was determined for 128 patients (82% males, 67 ± 9 years). Peak oxygen uptake was measured before and after the 12-week intervention. The ACE I/D polymorphism frequency was n = 48 for D/D homozygotes, n = 61 for I/D heterozygotes and n = 19 for I/I homozygotes. Baseline peak oxygen uptake was 23.3 ± 5.0 ml/kg/min in D/D homozygotes, 22.1 ± 5.3 ml/kg/min in I/D heterozygotes and 23.1 ± 6.0 ml/kg/min in I/I homozygotes, with no statistical differences between genotype groups (P = 0.50). The ACE I/D polymorphism frequency in the exercise group was n = 26 for D/D, n = 21 for I/D and n = 12 for I/I. After exercise training, peak oxygen uptake was increased (P < 0.001) in D/D homozygotes by 2.6 ± 1.7 ml/kg/min, in I/D heterozygotes by 2.7 ± 1.9 ml/kg/min, and in I/I homozygotes by 2.1 ± 1.3 ml/kg/min. However, the improvements were similar between genotype groups (time × genotype, P = 0.55). In conclusion, the ACE I/D polymorphism does not affect baseline exercise capacity or exercise capacity gains in response to 12 weeks of high-intensity exercise training in patients with stable CAD.

Clinical trial registration: www.clinicaltrials.gov (NCT04268992).
Metabolomic analysis indicated changes in triacylglycerols’ levels as a result of training in Whippet dogs
Authors: Miazga Katarzyna , Kopczyńska Klaudia , Szaluś-Jordanow Olga , Moroz-Fik Agata , Wilczak Jacek , Barszcz Karolina , Cywińska Anna
Published: October 2023

Regular physical effort produces metabolic changes manifested as adaptation to exercise and increasing performance. In humans these changes have been characterized at metabolome level as depending on the discipline. However, all sports involve some level of changes in protein, carbohydrate and lipid metabolism. Recently, also performance horses have been subjected to metabolic analyses, but similar studies were lacking in sports dogs. In this study we performed the metabolomic analysis in plasma of Whippet dogs regularly trained and competing in coursing events, and untrained dogs of the same breed, fed with the same diet. We have also compared the hematological and blood biochemical results in these two groups of dogs. Basic blood tests indicated that enzymes related to lipid metabolism (lipase and gamma-glutamyltransferase) differed considerably between the groups. Metabolomic analysis of plasma confirmed the metabolic shift expressed as the differences in triacylglycerols levels between training and non-training dogs, aimed at improving the use of fatty acids as a source of energy during exertion. Surprisingly, other classes of metabolites were only hardly changed when comparing training and non-training Whippets.
Striking efficacy of a vaccine targeting TOP2A for triple-negative breast cancer immunoprevention
Authors: Lee Sang Beom , Pan Jing , Xiong Donghai , Palen Katie , Johnson Bryon , Lubet Ronald A. , Shoemaker Robert H. , Green Jeffrey E. , Fernando Romaine Ingrid , Sei Shizuko , You Ming , Wang Yian
Published: October 2023

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer that has a poor prognosis. TOP2A is a key enzyme in DNA replication and is a therapeutic target for breast and other cancers. TOP2A-specific Th1-promoting epitopes with optimal binding affinity to MHC II were identified using a combined scoring system. The multi-peptide TOP2A vaccine elicited a robust immunologic response in immunized mice, as demonstrated by the significant production of Th1 cytokines from immunized animals’ splenocytes stimulated in vitro with TOP2A peptides. Anti-tumor efficacy of the TOP2A vaccine was demonstrated in a syngeneic TNBC mouse model, in which pre-graft preventive vaccination was associated with significantly decreased tumor growth as compared to adjuvant control. In a genetically engineered mouse (GEM) model of TNBC, vaccinated animals demonstrated a significant reduction in tumor incidence and average tumor volume compared to adjuvant control. Finally, we examined TCR sequences in CD4 tumor Infiltrating lymphocytes (TIL) from vaccinated mice and found that the TIL contained TCR sequences specific to the three vaccine peptides. These data indicate that our newly developed multi-peptide TOP2A vaccine is highly immunogenic, elicits TILs with vaccine specific TCRs, and is highly effective in preventing and intercepting TNBC development and progression in vivo.
Co-based metal–organic frameworks synthesized from poly(ethylene terephthalate) waste plastics for rapid detection of p-phenylenediamine
Authors: Xiao Yanteng , Wu Kangbing
Published: October 2023

Converting plastic waste into value-added electrochemical materials for hazardous PPD detection.
Probe the nanoparticle–nucleus interaction via coarse-grained molecular model
Authors: Zhang Liuyang , Liu Ning , Wang Xianqiao
Published: October 2023

This paper have systematically studied the effect of size, surface modification and rigidity on NP transport through the nuclear pore complex.
Easy and accurate computation of energy barriers for carbocation solvation: an expeditious tool to face carbocation chemistry
Authors: Martínez Antonio G. , Siehl Hans-Ulrich , de la Moya Santiago , Gómez Pedro C.
Published: October 2023

An expeditious procedure for the challenging computation of the free energy barriers (ΔG≠) for the solvation of carbocations is presented.
Nanobubble-induced significant reduction of the interfacial thermal conductance for few-layer graphene
Authors: Qu Zhao-Xia , Jiang Jin-Wu
Published: October 2023

A schematic diagram of the heat dissipation model and ITC of structure with different gas molecule numbers.
Electric-field induced half-metallic properties in an experimentally synthesized CrSBr monolayer
Authors: Guo Hao-Tian , Guo San-Dong , Ang Yee Sin
Published: October 2023

When an out-of-plane electric field is applied, the electronic bands in different layers will stagger, resulting in half-metallic behavior.
An integrated framework to develop an efficient valid green (EVG) HPLC method for the assessment of antimicrobial pollutants with potential threats to human health in aquatic systems
Authors: Saleh Sarah S. , Lotfy Hayam M. , Elbalkiny Heba T.
Published: October 2023

The persistence of antimicrobial drugs in aquatic environments has raised critical concerns about their possible impact on drinkable water quality and human health.
Asymmetric synthesis of (E)-Secobutanolides: total synthesis and structural revision of (+)-Litseakolide F and G
Authors: Nam Dong Guk , Lee Jin Won , Jung Hyun Sil , Ryu Do Hyun
Published: October 2023

Asymmetric syntheses of secobutanolide series and Litseakolide F and G were successfully achieved using catalytic MBH reaction and Z → E isomerization. These syntheses revised the absolute configuration of natural (+)-Litseakolide F and G.
Reducing intersystem crossing rates of boron emitters for high-efficiency and long-lifetime deep-blue OLEDs
Authors: Bai Keyan , Li Mengke , Tan Xiaofeng , Dai Lei , Liang Kaichun , Li Huiyang , Su Shi-Jian
Published: October 2023

An external quantum efficiency of 6.7% and a long operational lifetime of 136 h at 1000 cd m−2 were simultaneously realized for organic light-emitting diodes based on the deep-blue boron emitter (B-N-S-3), owing to the reduced intersystem crossing rate of the emitter.
Enhancement of crystalline quality and solar-blind photodetection characteristics of ε-Ga2O3 films by introducing Zn impurity
Authors: Sun Xuan , Liu Kewei , Chen Xing , Zhu Yongxue , Cheng Zhen , Yang Jialin , Li Binghui , Liu Lei , Shen Dezhen
Published: October 2023

In this work, pure and Zn-doped ε-Ga2O3 films were grown by MOVCD. The improvement in the crystalline quality and the UV photodetection performance of ε-Ga2O3 was demonstrated by introducing Zn impurity. The mechanism is also studied and discussed.
Insights into common fragile site instability: DNA replication challenges at DNA repeat sequences
Authors: Irony-Tur Sinai Michal , Kerem Batsheva
Published: October 2023

Common fragile sites (CFS) are specific genomic regions prone to chromosomal instability under conditions of DNA replication stress. CFSs manifest as breaks, gaps, and constrictions on metaphase chromosomes under mild replication stress. These replication-sensitive CFS regions are preferentially unstable during cancer development, as reflected by their association with copy number variants (CNVs) frequently arise in most tumor types. Over the years, it became clear that a combination of different characteristics underlies the enhanced sensitivity of CFSs to replication stress. As of today, there is a strong evidence that the core fragility regions along CFSs overlap with actively transcribed large genes with delayed replication timing upon replication stress. Recently, the mechanistic basis for CFS instability was further extended to regions which span topologically associated domain (TAD) boundaries, generating a fragility signature composed of replication, transcription and genome organization. The presence of difficult-to-replicate AT-rich repeats was one of the early features suggested to characterize a subgroup of CFSs. These long stretches of AT-dinucleotide have the potential to fold into stable secondary structures which may impede replication fork progression, leaving the region under-replicated. Here, we focus on the molecular mechanisms underlying repeat instability at CFSs and on the proteins involved in the resolution of secondary structure impediments arising along repetitive sequence elements which are essential for the maintenance of genome stability.
Encoding Coefficient Similarity‐Based Multifeature Sparse Representation for Finger Vein Recognition
Authors: Zhou Lizhen , Yang Lu , Fu Deqian , Yang Gongping
Published: October 2023

Finger vein recognition is a promising biometric technology that has received significant research attention. However, most of the existing works often relied on a single feature, which failed to fully exploit the discriminative information in finger vein images, and therefore led to a limited recognition performance. To overcome this limitation, this paper proposes an encoding coefficient similarity‐based multifeature sparse representation method for finger vein recognition. The proposed method not only uses multiple features to extract comprehensive information from finger vein images, but also obtains more discriminative information through constraints in the objective function. The sparsity constraint retains the key information of each feature, and the similarity constraint explores the shared information among the features. Furthermore, the proposed method is capable of fusing all kinds of features, not limited to specific ones. The optimization problem of the proposed method is efficiently solved using the alternating direction multiplier method algorithm. Experimental results on two public finger vein databases HKPU‐FV and SDU‐FV show that the proposed method achieves good recognition performance.
Atmospheric dynamics and shock waves in RR Lyr
Authors: Gillet D. , Sefyani F. L. , Benhida A. , Mauclaire B. , El Youssoufi D. , de France T. , Benkhaldoun Z. , Lailly P.
Published: October 2023

Context. Although spectroscopic observations of RR Lyrae stars have been underway for almost a century, the fact that the hydrogen line exhibits three successive emissions in each pulsation cycle is still a very recent discovery.

Aims. The purpose of the present study is to clarify the physical origin of these three emissions and their connection to atmospheric dynamics and to examine the influence of Blazhko modulation on their intensity.

Methods. We used 2437 high-resolution spectra over a total of 81 nights taken by the ELODIE spectrograph (Haute Provence Observatory, France) in the years 1994–1997, rounded out with a 2015 run from Oukaïmeden Observatory (Morocco). We performed a detailed analysis of the line profile variations over the whole pulsation cycle.

Results. Based on the blueshift of the main Hα emission, the velocity of the hypersonic shock front was estimated at between 100 and 150 ± 10 km s−1 (Mach number between 10 and 15). It has been established that the shock velocity increases from the minimum Blazhko to its maximum and afterward, it gradually decreases to the Blazhko minimum to start growing again. This observational result is consistent with the shock model proposed in 2013 to explain the Blazhko effect. The intensity of the Hα emission increases with the shock velocity up to a maximum value around 137 km s−1 and then decreases as the shock velocity increases further. This effect would be the consequence of the increasingly important ionization of the atoms in the radiative shock wake. The second (blueshifted) Hα emission is the consequence of an approximately constant supersonic compression (Mach number between 2 and 3) of the upper atmosphere falling onto the photospheric layers, during 3 to 16% of the pulsation period. Finally, the third Hα emission (P-Cygni profile) would be the consequence of the expansion of the high atmosphere induced by the shock wave during its final weakening.
Orbit determination for the binary Cepheid V1344 Aql
Authors: Cseh B. , Csörnyei G. , Szabados L. , Csák B. , Kovács J. , Kriskovics L. , Pál A.
Published: October 2023

Context. Binary Cepheids play an important role in the investigation of the calibration of the classical Cepheid period-luminosity relationship. Therefore, a thorough study of individual Cepheids belonging to binary systems is necessary.

Aims. Our aim is to determine the orbit of the binary system V1344 Aql using newly observed and earlier published spectroscopic and photometric data.

Methods. We collected new radial velocity observations using medium resolution (R ≈ 11 000 and R ⪅ 20 000) spectrographs, and we updated the pulsation period of the Cepheid based on available photometric observations using an O − C diagram. Separating the pulsational and orbital radial velocity variations for each observational season (year), we determined the orbital solution for the system using χ2 minimisation.

Results. The updated pulsation period of the Cepheid estimated for the epoch of HJD 2458955.83 is 7.476826 days. We determined orbital elements for the first time in the literature. The orbital period of the system is about 34.6 yr, with an eccentricity of e = 0.22.
Kinetic and mechanical properties of boronized AISI 1020 steel with Baybora-2 powder
Authors: Yamanel Bünyamin , Erdem Oguz , Bayça Salih Ugur , Bican Osman
Published: October 2023

In this study, package boronizing process was applied to AISI 1020 steel by using Baybora-2 boronizing agent and the kinetics of boronizing process was investigated. The pack boronizing process was performed at 1223 and 1323 K temperatures for 2, 4 and 6 h. The properties of the boride layer formed on the surface as a result of the boronizing process were determined using optical microscopy and SEM analysis. XRD analysis was performed to determine the phases formed in the boride layer. As a result of the analysis, it was determined that the boride layer consisted of FeB and Fe2B phases. It was determined that the thickness of the boride layer increased with the increase of boronizing time and temperature. While the boride layer thickness for the temperature of 1223 K was between 115 and 196.3 μm, the boride layer thickness for the temperature of 1323 K was found to be between 157.2 and 304.7 μm. In this study, a boriding powder, patented and under development, was used and a surface layer with a hardness of 2224 HV was obtained on the surface of AISI 1020 steel. This hardness value is approximately 5 times the hardness values of steels hardened by traditional surface hardening methods such as cementation and nitriding. Also, considering the boride layer thicknesses, the activation energy was calculated as 162.26 kJ/mol using the classical kinetic method.
Price strategy of community fresh food e-commerce considering the heterogeneous needs of consumers and fresh quality transparency
Authors: Jiang Bing , Liu Xiaoling , Wang Chong , Luo Hongbing , Liu Jiankang , Liu Cheng , Ji Zhenyi , Xia Dong
Published: October 2023

High online operating costs and low consumer utility still need to be addressed in the sales of community fresh e-commerce. Herein, we develop a new community fresh marketing model composed of retailers for online operating costs and consumers for low consumer utility by dividing community consumers into essential type and expectant type in this study. Then, the profit functions of community fresh retailers are developed in this study according to utility theory. Finally, a revised model of the fresh quality transparency (FQT) factor is conducted and discussed in this study. The results suggest that the profits obtained from essential consumers and expectant consumers by the community fresh e-commerce retailers are higher within a certain range of freshness costs compared to the basic model’s projection; meanwhile, the profits from expectant consumers contribute more than those from essential consumers. However, if the freshness cost exceeds a certain critical value, the abovementioned profits predicted from the new model will be lower. This study enriches the supply chain theory of community fresh food and provides retailers with theoretical guidance on differentiated services and pricing to better match the needs of community consumers.
Portfolio optimization based on bi-objective linear programming
Authors: Izadi Marzie , Yaghoobi Mohammad Ali
Published: October 2023

In this study, we deal with a portfolio optimization problem including both risky and risk-free assets. We use the infinity norm criterion to measure portfolio risk and formulate the problem as a bi-objective linear optimization problem. Then, a single objective linear program is considered related to the bi-objective optimization problem. Using the well-known Karush-Kuhn-Tucker optimality conditions, we obtain analytic formula for an optimal solution. Moreover, we determine the whole efficient frontier by multi-criteria optimization techniques. Based on the theoretical results, two algorithms are proposed for finding the portfolio weights and the efficient frontier. Numerical examples are given for illustrating the new models and algorithms. Additionally, a simulation study has been conducted to assess the performance of the proposed method.
Efficient Synthesis of (Z)-4-((Substituted phenylamino)methyl­idene)isoquinoline-1,3(2H,4H)-diones Using the Eschenmoser Coupling Reaction
Authors: Hanusek Jiří , Marek Lukáš , Váňa Jiří , Svoboda Jan , Svobodová Markéta
Published: October 2023

A novel synthetic strategy involving the Eschenmoser coupling reaction of 4-bromoisoquinoline-1,3(2H,4H)-diones with substituted thioformanilides, thioacetanilides, and thiobenzanilides gave 18 (Z)-4-((substituted phenylamino)methylidene)isoquinoline-1,3(2H,4H)-diones. The reaction occurs under mild conditions (DMF or MeCN, 25–60 °C) without any base or thiophile and in good yields (43–95%). Furthermore, for the synthesis of starting thioformanilides carrying basic substituents, a new thioacylation protocol was developed that involves a thioacylating agent formed from carbon disulfide and lithium triethylborohydride.
[Pyridine–SO3H]ZnCl3: A Multipurpose Catalyst for A3 Coupling Synthesis of Propargylamines under Mild Conditions
Authors: Moosavi-Zare Ahmad Reza , Rezaei-Gohar Mohammad , Tavasoli Mahsa , Goudarziafshar Hamid
Published: October 2023

N-Sulfopyridin-1-ium monozinc(II) trichloride ([NSPy]ZnCl3) was prepared and used as a multipurpose catalyst for the synthesis of propargylamines by the A3 coupling reaction of aromatic aldehydes, alkynes, and secondary amines under mild conditions. In this reaction, the carbonyl group in the aldehyde was activated by the acidic part in the catalyst, and the C–H activation of phenylacetylene was carried out by zinc.
ESG criteria and the credit risk of corporate bond portfolios
Authors: Höck Andre , Bauckloh Tobias , Dumrose Maurice , Klein Christian
Published: October 2023

Demand for sustainable fixed-income investment solutions is surging but there is hardly research on the impact of sustainability on the risk characteristics of fixed-income portfolios. This study examines the impact of sustainability on the credit risk exposure of corporate bond portfolios between 2013 and 2020 by analyzing the returns of sustainable and non-sustainable portfolios using two different asset pricing models and environmental, social, and governance (ESG) ratings from different providers. Controlling for a set of portfolio characteristics, our results show that sustainable portfolios are significantly less exposed to credit risk than their non-sustainable peer portfolios. This finding implies that considering ESG criteria in portfolio management is a suitable means to systematically manage credit risk. Being the first study to investigate the relationship between sustainability and credit risk on a portfolio level, this study contributes to the understanding of the effects of ESG criteria in portfolio management and provides academics and investment professionals with valuable insights.
Observation and formation mechanism of 360° domain wall rings in synthetic anti-ferromagnets with interlayer chiral interactions
Authors: Cascales Sandoval Miguel A. , Hierro-Rodríguez A. , Ruiz-Gómez S. , Skoric L. , Donnelly C. , Niño M. A. , Vedmedenko E. Y. , McGrouther D. , McVitie S. , Flewett S. , Jaouen N. , Foerster M. , Fernández-Pacheco A.
Published: October 2023

The interlayer Dzyaloshinskii–Moriya interaction (IL-DMI) chirally couples spins in different ferromagnetic layers of multilayer heterostructures. So far, samples with IL-DMI have been investigated utilizing magnetometry and magnetotransport techniques, where the interaction manifests as a tunable chiral exchange bias field. Here, we investigate the nanoscale configuration of the magnetization vector in a synthetic anti-ferromagnet (SAF) with IL-DMI, after applying demagnetizing field sequences. We add different global magnetic field offsets to the demagnetizing sequence in order to investigate the states that form when the IL-DMI exchange bias field is fully or partially compensated. For magnetic imaging and vector reconstruction of the remanent magnetic states, we utilize x-ray magnetic circular dichroism photoemission electron microscopy, evidencing the formation of 360° domain wall rings of typically 0.5–3.0 μm in diameter. These spin textures are only observed when the exchange bias field due to the IL-DMI is not perfectly compensated by the magnetic field offset. From a combination of micromagnetic simulations, magnetic charge distribution, and topology arguments, we conclude that a non-zero remanent effective field with components both parallel and perpendicular to the anisotropy axis of the SAF is necessary to observe the rings. This work shows how the exchange bias field due to IL-DMI can lead to complex metastable spin states during reversal, important for the development of future spintronic devices.
Design of multi-frequency point, high-isolation switches for micro-channel plate data acquisition
Authors: Yang Yihao , Gou Yongsheng , Yang Yang , Feng Penghui , Wang Bo , Liu Baiyu , Wei Jianan , Tian Jinshou , Zhao Wei
Published: October 2023

In order to replace the phosphor screen of a proximity-gated x-ray framing camera with a readout circuit using a time-interleaved structure, this paper carries out the design of a high-isolation RF switch. In this paper, a Metal-Oxide-Semiconductor Field Effect Tube (MOSFET) switching circuit is designed to achieve high isolation and low insertion loss at 0.5–3 GHz. This solves the problem that the switching circuit cannot be turned off properly due to the parasitic capacitance of MOSFETs in the process of RF signal transmission, resulting in signal feedthrough. It also ensures that the input signal can be transmitted to the output intact when the switching circuit is turned on. High isolation is achieved by using parallel resonance to increase the voltage division and series resonance to leak the current. The switch achieves 76 dB isolation and 0.07 dB insertion loss at 1 GHz frequency. Isolation is increased by adding parallel branches near the 2 and 3 GHz frequency points, achieving greater than 33 dB isolation from 0.5 to 3 GHz.
Robust excitation of C-band quantum dots for quantum communication
Authors: Vyvlecka Michal , Jehle Lennart , Nawrath Cornelius , Giorgino Francesco , Bozzio Mathieu , Sittig Robert , Jetter Michael , Portalupi Simone L. , Michler Peter , Walther Philip
Published: October 2023

Building a quantum internet requires efficient and reliable quantum hardware, from photonic sources to quantum repeaters and detectors, ideally operating at telecommunication wavelengths. Thanks to their high brightness and single-photon purity, quantum dot (QD) sources hold the promise to achieve high communication rates for quantum-secured network applications. Furthermore, it was recently shown that excitation schemes such as longitudinal acoustic phonon-assisted (LA) pumping provide security benefits by scrambling the coherence between the emitted photon-number states. In this work, we investigate further advantages of LA-pumped quantum dots with emission in the telecom C-band as a core hardware component of the quantum internet. We experimentally demonstrate how varying the pump power and spectral detuning with respect to the excitonic transition can improve quantum-secured communication rates and provide stable emission statistics regardless of network-environment fluctuations. These findings have significant implications for general implementations of QD single-photon sources in practical quantum communication networks.
Exploring the parameter space of an endohedral atom in a cylindrical cavity
Authors: Panchagnula K. , Thom A. J. W.
Published: October 2023

Endohedral fullerenes, or endofullerenes, are chemical systems of fullerene cages encapsulating single atoms or small molecules. These species provide an interesting challenge of Potential Energy Surface determination as examples of non-covalently bonded, bound systems. While the majority of studies focus on C60 as the encapsulating cage, introducing some anisotropy by using a different fullerene, e.g., C70 can unveil a double well potential along the unique axis. By approximating the potential as a pairwise Lennard-Jones (LJ) summation over the fixed C cage atoms, the parameter space of the Hamiltonian includes three tunable variables: (M, ɛ, σ) representing the mass of the trapped species, the LJ energy, and length scales respectively. Fixing the mass and allowing the others to vary can imitate the potentials of endohedral species trapped in more elongated fullerenes. We choose to explore the LJ parameter space of an endohedral atom in C70 with ɛ ∈ [20, 150 cm−1], and σ ∈ [2.85, 3.05 Å]. As the barrier height and positions of these wells vary between [1, 264 cm−1] and [0.35, 0.85 Å] respectively, using a 3D direct product basis of 1D harmonic oscillator (HO) wavefunctions centred at the origin where there is a local maximum is unphysical. Instead we propose the use of a non-orthogonal basis set, using 1D HO wavefunctions centred in each minimum and compare this to other choices. The ground state energy of the X@C70 is tracked across the LJ parameter space, along with its corresponding nuclear translational wavefunctions. A classification of the wavefunction characteristics, namely the prolateness and “peanut-likeness” based on its statistical moments is also proposed. Excited states of longer fullerenes are assigned quantum numbers, and the fundamental transitions of Ne@C70 are tracked across the parameter space.
The evolution of a three-dimensional microbubble at a corner in a Maxwell fluid
Authors: O'Brien E. N. , Mahmud M. , Smith W. R. , Wang Q. X. , Phillips T. N.
Published: October 2023

Bubbles often appear in non-Newtonian liquids from nature, engineering to biomedical applications, but their study has been under research compared to their Newtonian counterpart. Here, we extend the axisymmetric modeling of Lind and Phillips to three-dimensional modeling. The approach is based on the boundary integral method coupled with the Maxwell constitutive equation. The flow is assumed to have moderate to high Reynolds numbers and, thus, is irrotational in the bulk domain. The viscoelastic effects are incorporated approximately in the normal stress balance at the bubble surface. The numerical model has excellent agreement with the corresponding Rayleigh–Plesset equation for spherical bubbles in a non-Newtonian liquid. Computations are carried out for a bubble near a corner at various angles. The numerical results agree very well with the experiments for bubbles in a Newtonian fluid in a corner. As the Deborah number increases, the amplitude and period of the bubble oscillation increase, the bubble migration to the corner enhances, and the bubble jet is broader, flatter, and inclined more to the further boundary. This implies an improvement to surface cleaning of all surrounding boundaries for ultrasonic cavitation cleaning and results in greater administration of noninvasive therapy and drug delivery.
Improvement of turbulent flow in a bend using rotational guide vane: A shape optimization
Authors: Yagmur Sercan , Gumus Mehmet Sefa , Dogan Sercan , Kalyoncu Mete
Published: October 2023

The present study aims to minimize velocity disruption using rotational guide vane (RGV) before the 90° pipe bend where the curvature ratio is r/D = 1.0 at Re = 3 × 104. The combination of computational fluid dynamics and genetic algorithm is used as a tool for the geometric optimization of RGV. The SST k–ω turbulence model was preferred in flow analysis. The number of blade, the blade angle, and the location of RGV are the geometric parameters to be optimized. A new evaluation method of the velocity distribution after the bend is proposed. The objective function is defined as velocity distribution mean squared error that is based on the comparison of the velocity distribution on the cross section after the bend with the fully developed flow in a straight pipe under the same conditions. As a result of a series of optimization processes, velocity distribution at the 90° bend exit is compared between optimized RGV and without guide vane. The results show that the optimized RGV improves velocity distribution at the bend exit. Compared to the without guide vane case, the optimized RGV has delayed flow separation from α = 37° to 56°, and the flow reattachment point moves from x/D = 0.5 to 0 at the bend exit. Thanks to optimized RGV, the counter-rotating Dean vortices merged to form a single vortex at the center of the pipe. In addition, significant reduction in turbulent kinetic energy was observed, approximately 50% when using the optimized RGV compared to the without guide vane case.
Effect of water jet area on mitigation of vortex rope in a Francis turbine
Authors: Kumar Sandeep , Gandhi Bhupendra K.
Published: October 2023

The rotating vortex rope (RVR) is normally formed at part load operating conditions, which develops flow instability in the draft tube (DT) cone of a Francis turbine. The detrimental effects of RVR reduce the life and performance of the turbine. The present work mitigates RVR through axial water jet injection in the DT cone. This paper extends the author's previous work on water injection with a 50% reduction in the water jet area through two nozzles with a diameter of 12.7 mm. The effect of area reduction is analyzed by spectral analysis like power spectrum density and spatial harmonic decomposition of the pressure field measured at the wall of the cone. The effect of water jet injection on synchronous and asynchronous pressure pulsations is analyzed at both measurement planes of the cone. The improvement in pressure recovery in the cone and turbine efficiency due to water jet injection is also analyzed. The water is injected at 0.5%–2% of the turbine inlet flow at 22.10° guide vane opening.
Pressure–flow rate relationship and its polynomial expansion for laminar flow in a circular pipe based on exponential viscosity-pressure characteristics: An extension of classical Poiseuille's law
Authors: Wu Jia-Bin , Li Li
Published: October 2023

Laminar flow in circular pipes is widespread in various fields. Poiseuille's law is the classical equation describing the pressure–flow rate relationship for laminar flow in circular pipes. However, the fluid viscosity is treated as a constant in Poiseuille's law. Therefore, Poiseuille's law cannot be used to accurately analyze fluids that have viscosities that vary exponentially with pressure, such as hydraulic oils and lubricating oils. In this study, with the exponential viscosity-pressure characteristics, a total of four simple and explicit equations are given for calculating the flow rate or pressure difference of the pipe, and corresponding polynomial expansions are derived based on the Taylor series. Experimental tests and computational fluid dynamics simulations are carried out to verify the correctness of the theoretical equations, with error of less than 6% and 2%, respectively. An error analysis of the theoretical equations for different numbers of polynomial terms is also performed. The results show that the proposed theoretical equations all degenerate to the classical Poiseuille's law when the number of polynomial terms is taken to be 1, and the relative errors are less than ±5% for viscosity changes less than 10%. When the number of terms is 2, the relative error is less than ±5% for viscosity changes less than 40%. In the calculation of connection pipelines of a deep-sea hydraulic actuator, the difference in pressure loss calculated with or without viscosity change is 31.47% and reaches up to 5.7202 MPa, which shows the practical value of this research in piping systems.
Optoacoustic detection of nanosecond time scale photoinduced lensing effects in liquids
Authors: Bergmann E. V. , Lukasievicz G. V. B. , Lendl B. , Sampaio A. R. , Zanuto V. S. , Baesso M. L. , Malacarne L. C. , Astrath N. G. C.
Published: October 2023

An all-optical photoinduced lensing method is used to excite and monitor acoustic waves in liquids. Following optical absorption, the laser pulse induces a localized temperature gradient that launches pressure waves in the excited region at the nanosecond time scale. This generates a lens-like optical element in the sample. A probe laser beam senses the refractive index change due to the acoustic and thermal effects. Piezo-optic and thermo-optic coefficients govern how the refractive index of a material changes in response to mechanical stress and temperature variations, respectively. These effects are connected to the physical properties of the liquids and can be accessed by theoretically describing the intensity signal. A complete set of physical properties of ten liquids are quantitatively described in this work. These effects find applications in a wide range of fields, from optical communication, ultrasonic imaging, and sensing to adaptive optics and fundamental research.
Review of Scientific Instruments New Products
Authors: Mandelis Andreas
Published: October 2023

In order to supplement manufacturers’ information, this department will welcome the submission by our readers of brief communications reporting measurements on the physical properties of materials that supersede earlier data or suggest new research applications.
An amino-domino model described by a cross-peptide-bond Ramachandran plot defines amino acid pairs as local structural units
Authors: Rosenberg Aviv A. , Yehishalom Nitsan , Marx Ailie , Bronstein Alex M.
Published: October 2023

Protein structure, both at the global and local level, dictates function. Proteins fold from chains of amino acids, forming secondary structures, α-helices and β-strands, that, at least for globular proteins, subsequently fold into a three-dimensional structure. Here, we show that a Ramachandran-type plot focusing on the two dihedral angles separated by the peptide bond, and entirely contained within an amino acid pair, defines a local structural unit. We further demonstrate the usefulness of this cross-peptide-bond Ramachandran plot by showing that it captures β-turn conformations in coil regions, that traditional Ramachandran plot outliers fall into occupied regions of our plot, and that thermophilic proteins prefer specific amino acid pair conformations. Further, we demonstrate experimentally that the effect of a point mutation on backbone conformation and protein stability depends on the amino acid pair context, i.e., the identity of the adjacent amino acid, in a manner predictable by our method.
Interspecies interactions determine growth dynamics of biopolymer-degrading populations in microbial communities
Authors: D’Souza Glen , Schwartzman Julia , Keegstra Johannes , Schreier Jeremy E. , Daniels Michael , Cordero Otto X. , Stocker Roman , Ackermann Martin
Published: October 2023

Microbial communities perform essential ecosystem functions such as the remineralization of organic carbon that exists as biopolymers. The first step in mineralization is performed by biopolymer degraders, which harbor enzymes that can break down polymers into constituent oligo- or monomeric forms. The released nutrients not only allow degraders to grow, but also promote growth of cells that either consume the degradation products, i.e., exploiters, or consume metabolites released by the degraders or exploiters, i.e., scavengers. It is currently not clear how such remineralizing communities assemble at the microscale—how interactions between the different guilds influence their growth and spatial distribution, and hence the development and dynamics of the community. Here, we address this knowledge gap by studying marine microbial communities that grow on the abundant marine biopolymer alginate. We used batch growth assays and microfluidics coupled to time-lapse microscopy to quantitatively investigate growth and spatial distribution of single cells. We found that the presence of exploiters or scavengers alters the spatial distribution of degrader cells. In general, exploiters and scavengers—which we collectively refer to as cross-feeder cells—slowed down the growth of degrader cells. In addition, coexistence with cross-feeders altered the production of the extracellular enzymes that break down polymers by degrader cells. Our findings reveal that ecological interactions by nondegrading community members have a profound impact on the functions of microbial communities that remineralize carbon biopolymers in nature.
Olfactory threat extinction in the piriform cortex: An age-dependent employment of NMDA receptor-dependent long-term depression
Authors: Sepahvand Tayebeh , Nazari Negar , Qin Tian , Rajani Vishaal , Yuan Qi
Published: October 2023

Extinction of threat memory is a measure of behavioral flexibility. In the absence of additional reinforcement, the extinction of learned behaviors allows animals and humans to adapt to their changing environment. Extinction mechanisms and their therapeutic implications for maladaptive learning have been extensively studied. However, how aging affects extinction learning is much less understood. Using a rat model of olfactory threat extinction, we show that the extinction of olfactory threat memory is impaired in aged Sprague-Darley rats. Following extinction training, long-term depression (LTD) in the piriform cortex (PC) was inducible ex vivo in aged rats and was NMDA receptor (NMDAR)-independent. On the other hand, adult rats acquired successful olfactory threat extinction, and LTD was not inducible following extinction training. Neuronal cFos activation in the posterior PC correlated with learning and extinction performance in rats. NMDAR blockade either systemically or locally in the PC during extinction training prevented successful extinction in adult rats, following which NMDAR-dependent LTD became inducible ex vivo. This suggests that extinction learning employs NMDAR-dependent LTD mechanisms in the PC of adult rats, thus occluding further LTD induction ex vivo. The rescue of olfactory threat extinction in aged rats by D-cycloserine, a partial NMDAR agonist, suggests that the impairment in olfactory threat extinction of aged animals may relate to NMDAR hypofunctioning and a lack of NMDAR-dependent LTD. These findings are consistent with an age-related switch from NMDAR-dependent to NMDAR-independent LTD in the PC. Optimizing NMDAR function in sensory cortices may improve learning and flexible behavior in the aged population.
Thermal transport of graphene-C3B superlattices and van der Waals heterostructures: a molecular dynamics study
Authors: Zhang Guangzheng , Dong Shilin , Wang Xinyu , Xin Gongming
Published: October 2023

Two-dimensional (2D) materials have attracted more and more attention due to their excellent properties. In this work, we systematically explore the heat transport properties of Graphene-C3B (GRA-C3B) superlattices and van der Waals (vdW) heterostructures using molecular dynamics method. The effects of interface types and heat flow directions on the in-plane interfacial thermal resistance (ITRip) are analyzed. Obvious thermal rectification is detected in the more energy stable interface, GRA zigzag-C3B zigzag (ZZ) interface, which also has the minimum value of ITRip. The dependence of the superlattices thermal conductivity (k) of the ZZ interface on the period length (l

p
) is investigated. The results show that when the l

p
is 3.5 nm, the k reaches a minimum value of 35.52 W m−1 K−1, indicating a transition stage from coherent phonon transport to incoherent phonon transport. Afterwards, the effects of system size, temperature, coupling strength and vacancy defect on the out-of-plane interfacial thermal resistance (ITRop) are evaluated. With the increase of temperature, coupling strength and vacancy defect, ITRop are found to reduce effectively due to the enhanced Umklapp phonon scattering and increased probability of energy transfer. Phonon density of states and phonon participation ratio is evaluated to reveal phonon behavior during heat transport. This work is expected to provide essential guidance for the thermal management of nanoelectronics based on 2D monolayer GRA and C3B.