bluuebunny/crossref_metadata_2025 huggingface dataset:
Tracking the emergence of epitaxial metal–oxide interfaces from precursor alloys
Authors: Wen Yu , Abe Hideki , Mitsuishi Kazutaka , Hashimoto Ayako
Published: September 2021

The oxidation process of a Pt5Ce alloy that leads to self-assembled Pt/CeO2nanocomposites with an epitaxial heterointerface was elucidated by atomic-resolution transmission electron microscopy.
N- and O-doped hollow carbons constructed by self- and extrinsic activation for the oxygen reduction reaction and flexible zinc–air Batteries
Authors: Xie Qianjie , Si Wenfang , Shen Yehua , Wang Zheng , Uyama Hiroshi
Published: September 2021

A metal-free hollow carbon with N and O doped in a preferable configuration has been prepared by self- and extrinsic activation, showing superior oxygen reduction reaction (ORR) activity and flexible zinc–air battery (ZAB) performance.
Visible-light-promoted direct C3-trifluoromethylation and perfluoroalkylation of imidazopyridines
Authors: Li Meichen , Li Gaolin , Dai Chenxun , Zhou Wenjun , Zhan Wenqiang , Gao Muyang , Rong Yuan , Tan Ze , Deng Wei
Published: September 2021

Highly mono-selective trifluoromethylation and perfluoroalkylation at C3 of imidazo[1,2-a]pyridines were achieved via visible-light-promoted C–H bond functionalization of imidazo[1,2-a]pyridines without using any photoredox catalyst.
Design of an electrochemiluminescence detection system through the regulation of charge density in a microchannel
Authors: Huang Yanling , Lu Yilei , Huang Xiaobin , Wang Jian , Qiu Bin , Luo Fang , Lin Zhenyu
Published: September 2021

The microchannel-based target sensing and ECL reporting reactions were combined for the first time. This configuration separated the sensing and reporting reactions to achieve ionic current direct regulating ECL reporting.
The role of temperature in the formation of human–mimetic artificial cell membranes using droplet interface bilayers (DIBs)
Authors: Korner Jaime L. , Elvira Katherine S.
Published: September 2021

A systematic study of the role of temperature in human–mimetic droplet interface bilayer (DIB) formation.
Increasing ionic conductivity within thermoplastics via commercial additives results in a dramatic decrease in fiber diameter from melt electrospinning
Authors: Sheoran Neelam , Boland Brent , Thornton Samuel , Bochinski Jason R. , Clarke Laura I.
Published: September 2021

Role of conductivity and viscosity in determining jet size and fiber diameter in melt electrospinning is explored by new data and application of theory. Increasing conductivity via an additive leads to a large fraction of sub-micron diameter fibers.
Understanding interfacial segregation in polymer blend films with random and mixed side chain bottlebrush copolymer additives
Authors: Mei Hao , Mahalik Jyoti P. , Lee Dongjoo , Laws Travis S. , Terlier Tanguy , Stein Gila E. , Kumar Rajeev , Verduzco Rafael
Published: September 2021

We show that side-chain microstructure does not significantly impact surface enrichment of bottlebrush additives in blends with linear polymers.
The role of pro-domains in human growth factors and cytokines
Authors: Ratcliff Matthew , Zhou Richard Xu , Jermutus Lutz , Hyvönen Marko
Published: September 2021

Many growth factors and cytokines are produced as larger precursors, containing pro-domains, that require proteolytic processing to release the bioactive ligand. These pro-domains can be significantly larger than the mature domains and can play an active role in the regulation of the ligands. Mining the UniProt database, we identified almost one hundred human growth factors and cytokines with pro-domains. These are spread across several unrelated protein families and vary in both their size and composition. The precise role of each pro-domain varies significantly between the protein families. Typically they are critical for controlling bioactivity and protein localisation, and they facilitate diverse mechanisms of activation. Significant gaps in our understanding remain for pro-domain function — particularly their fate once the bioactive ligand has been released. Here we provide an overview of pro-domain roles in human growth factors and cytokines, their processing, regulation and activation, localisation as well as therapeutic potential.
Bioengineering silk into blood vessels
Authors: Lam Yuen Ting , Tan Richard P. , Michael Praveesuda L. , Lau Kieran , Yang Nianji , Rnjak-Kovacina Jelena , Wise Steven G.
Published: September 2021

The rising incidence of cardiovascular disease has increased the demand for small diameter (<6 mm) synthetic vascular grafts for use in bypass surgery. Clinically available synthetic grafts (polyethylene terephthalate and expanded polytetrafluorethylene) are incredibly strong, but also highly hydrophobic and inelastic, leading to high rates of failure when used for small diameter bypass. The poor clinical outcomes of commercial synthetic grafts in this setting have driven significant research in search of new materials that retain favourable mechanical properties but offer improved biocompatibility. Over the last several decades, silk fibroin derived from Bombyx mori silkworms has emerged as a promising biomaterial for use in vascular applications. Progress has been driven by advances in silk manufacturing practices which have allowed unprecedented control over silk strength, architecture, and the ensuing biological response. Silk can now be manufactured to mimic the mechanical properties of native arteries, rapidly recover the native endothelial cell layer lining vessels, and direct positive vascular remodelling through the regulation of local inflammatory responses. This review summarises the advances in silk purification, processing and functionalisation which have allowed the production of robust vascular grafts with promise for future clinical application.
A multi‐agent system for itinerary suggestion in smart environments
Authors: De Paola Alessandra , Gaglio Salvatore , Giammanco Andrea , Lo Re Giuseppe , Morana Marco
Published: September 2021

Modern smart environments pose several challenges, among which the design of intelligent algorithms aimed to assist the users. When a variety of points of interest are available, for instance, trajectory recommendations are needed to suggest users the most suitable itineraries based on their interests and contextual constraints. Unfortunately, in many cases, these interests must be explicitly requested and their lack causes the so‐called cold‐start problem. Moreover, lengthy travelling distances and excessive crowdedness of specific points of interest make itinerary planning more difficult. To address these aspects, a multi‐agent itinerary suggestion system that aims at assisting the users in an online and collaborative way is proposed. A profiling agent is responsible for the detection of groups of users whose movements are characterised by similar semantic, spatial and temporal features; then, a recommendation agent leverages contextual information and dynamically associates the current user with the trajectory clusters according to a Multi‐Armed Bandit policy. Framing the trajectory recommendation as a reinforcement learning problem permits to provide high‐quality suggestions while avoiding both cold‐start and preference elicitation issues. The effectiveness of the approach is demonstrated by some deployments in real‐life scenarios, such as smart campuses and theme parks.
Effect of the upset pressure on Microstructure and Properties of Friction Welded Joints of 6082 aluminum alloy/304 stainless steel
Authors: Lu Gui-peng , Zhao Li-zhe , Liu Wei , Sun Yu-meng , Gong Wen-biao
Published: September 2021

The dissimilar connection between 6082 aluminum alloy and 304 stainless steel was realized by continuous drive friction welding. Microstructures of the joint were studied by optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffractometry (XRD). In the process of continuous drive welding, the intermetallic compounds (IMCs) Fe2Al5 phase was observed at the interface, the formation mechanism of IMC was discussed, and the corresponding analysis model was established. When the upset pressure in the range of 6–10 MPa, the element diffusion distance increases with the increase of upset pressure. The tensile strength of the joint increased firstly and then decreased with the increase of upset pressure. The joint’s maximum tensile strength can reach 234 MPa, and tensile fracture of the joint exhibited brittle-tough mixed fracture characteristics.
Locking Compression Plate as an External Fixator for the Treatment of Tibia Infected Bone Defects
Authors: Xiao Hong , Wang Shulin , Wang Feibo , Dong Sun , Shen Jie , Xie Zhao
Published: September 2021

Purpose This study was designed to observe the medium-term efficacy of an induced membrane technique combined with a locking compression plate as an external fixator for the
treatment of tibia infected bone defects.

Methods Patients with a tibial infection were admitted to our department between January 2013 and November 2014. All patients were treated with the induced membrane technique. In the
first stage, polymethyl methacrylate (PMMA) cement was implanted in the defects after debridement and then fixed with a locking compression plate (LCP) as an external fixator. In the second
stage, bone grafts were implanted to rebuild the defects. The external plates were replaced with nails in 57 patients (internal group), and the remaining 30 patients were not exchanged with
fixation (external group). The infection control rate, bone union rate, and complications of the two groups were compared.

Results Eighty-seven patients were enrolled in this study, and all patients had a minimum follow-up of 5 years (average 62.8 months) after grafting. Eighty-three patients (95.4%)
achieved bone union, and the average union time was 6.77 months. Five patients (5.7%) experienced recurrence of infection. Complications included pin tract infection, fixation loosening,
deformity connection, and limitation of joint range of motion (ROM). No significant differences in the infection control rate or bone defect union rate were noted between the two groups. The
overall rate of complications in the external group was 50%, which was greater than that noted in the internal group (21.1%).

Conclusions Locking compression plates are external fixators with smaller sizes that are easier to operate than conventional annular fixators or assembled external fixators. The use
of locking compression plates in combination with the induced membrane technique in the treatment of tibia infected bone defects can achieve good clinical efficacy after medium-term
follow-up.
Is Lumbar Puncture Needed? – Noninvasive Assessment of ICP Facilitates Decision Making in Patients with Suspected Idiopathic Intracranial Hypertension
Authors: Schmidt Bernhard , Czosnyka Marek , Cardim Danilo , Czosnyka Zofia , Rosengarten Bernhard
Published: September 2021

Purpose Idiopathic intracranial hypertension (IIH) usually occurs in obese women of childbearing age. Typical symptoms are headache and sight impairment. Lumbar puncture (LP) is routinely used for both diagnosis and therapy (via cerebrospinal fluid drainage) of IIH. In this study, noninvasively assessed intracranial pressure (nICP) was compared to LP pressure (LPP) in order to clarify its feasibility for the diagnosis of IIH.

Materials and Methods nICP was calculated using continuous signals of arterial blood pressure and cerebral blood flow velocity in the middle cerebral artery, a method which has been introduced recently. In 26 patients (f = 24, m = 2; age: 33 ± 11 years), nICP was assessed one hour prior to LPP. If LPP was > 20 cmH2O, lumbar drainage was performed, LPP was measured again, and also nICP was reassessed.

Results In total, LPP and nICP correlated with R = 0.85 (p < 0.001; N = 38). The mean difference of nICP-LPP was 0.45 ± 4.93 cmH2O. The capability of nICP to diagnose increased LPP (LPP > 20 cmH2O) was assessed by ROC analysis. The optimal cutoff for nICP was close to 20 cmH2O with both a sensitivity and specificity of 0.92. Presuming 20 cmH2O as a critical threshold for the indication of lumbar drainage, the clinical implications would coincide in both methods in 35 of 38 cases.

Conclusion The TCD-based nICP assessment seems to be suitable for a pre-diagnosis of increased LPP and might eliminated the need for painful lumbar puncture if low nICP is detected.
Outcomes of endoscopic resection for superficial duodenal tumors: 10 years’ experience in 18 Japanese high volume centers
Authors: Kato Motohiko , Takeuchi Yoji , Hoteya Shu , Oyama Tsuneo , Nonaka Satoru , Yoshimizu Shoichi , Kakushima Naomi , Ohata Ken , Yamamoto Hironori , Hara Yuko , Doyama Hisashi , Dohi Osamu , Yamasaki Yasushi , Ueyama Hiroya , Takimoto Kengo , Kurahara Koichi , Tashima Tomoaki , Abe Nobutsugu , Nakayama Atsushi , Oda Ichiro , Yahagi Naohisa
Published: September 2021

Background Data on endoscopic resection (ER) for superficial duodenal epithelial tumors (SDETs) are insufficient owing to their rarity. There are two main ER techniques for SDETs: endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD). In addition, modified EMR techniques, such as underwater EMR (UEMR) and cold polypectomy, are becoming popular. We conducted a large-scale retrospective multicenter study to clarify the detailed outcomes of duodenal ER.

Methods Patients with SDETs who underwent ER at 18 institutions from January 2008 to December 2018 were included. The rates of en bloc resection and delayed adverse events (AEs; defined as delayed bleeding or perforation) were analyzed. Local recurrence was analyzed using the Kaplan–Meier method.

Results In total, 3107 patients (including 1017 undergoing ESD) were included. En bloc resection rates were 79.1 %, 78.6 %, 86.8 %, and 94.8 %, and delayed AE rates were 0.5 %, 2.2 %, 2.8 %, and 6.8 % for cold polypectomy, UEMR, EMR and ESD, respectively. The delayed AE rate was significantly higher in the ESD group than in non-ESD groups for lesions < 19 mm (7.4 % vs. 1.9 %; P < 0.001), but not for lesions > 20 mm (6.1 % vs. 7.1 %; P = 0.64). The local recurrence rate was significantly lower in the ESD group than in the non-ESD groups (P < 0.001). Furthermore, for lesions > 30 mm, the cumulative local recurrence rate at 2 years was 22.6 % in the non-ESD groups compared with only 1.6 % in the ESD group (P < 0.001).

Conclusions ER outcomes for SDETs were generally acceptable. ESD by highly experienced endoscopists might be an option for very large SDETs.
Pregnancy Outcomes in Refractory Epilepsy Patients with Vagus Nerve Stimulation: Long-Term Single-Center Experience
Authors: Chrastina Jan , Dolezalova Irena , Novak Zdenek , Pešlová Eva , Brazdil Milan
Published: September 2021

Background and Study Aims Vagus nerve stimulation (VNS) has been employed worldwide as an adjunctive therapy in drug-resistant epilepsy patients. However, the mechanisms of VNS action potentially increase the risk of obstetric complications. The study presents the long-term single-center experience with pregnancies and childbirth in women with VNS for refractory epilepsy based on prospectively collected epileptologic data and a retrospective analysis of pregnancy, childbirth, and data about long-term child development.

Material and Methods From a group of patients with VNS implanted for refractory epilepsy between October 1999 and January 2018, all the women of childbearing age (younger than 40 years) were identified. After checking their hospital records for data about any pregnancies, the women with confirmed childbirth during active VNS stimulation and their general practitioners were interviewed based on a prepared questionnaire regarding their gynecologic history, the course of pregnancy and childbirth, gestational week, birth weight and length, any congenital anomalies of the child, and the child's psychomotor development, school performance, and somatic health problems.

Results From the group of 257 patients implanted with VNS for refractory epilepsy, 4 women (1.5%) became pregnant and gave birth (all on polypharmacotherapy). The mean interval from VNS implantation to birth was 44.3 months. Slight seizure worsening during the last trimester was reported in one woman. In one patient, acute caesarean section was required due to placental separation. Planned birth induction and caesarean section were used in the other two women because of their seizure disorder. No malfunction of the stimulation system was detected during pregnancy or after birth. No congenital malformations were observed. The two children who were of school age at the time of this study require special schooling.

Conclusions The study results confirmed a high rate of obstetric interventions in patients with VNS. Although no teratogenic effect of VNS has been proven, the higher incidence of children exposed to VNS needing special education requires attention.
An Immunoassay for Human Chorionic Gonadotropin in Cerebrospinal Fluid: Validation of a Modified-Approved Method for Accreditation by the College of American Pathologists
Authors: Hu Yao , Ni Jiajin , Zhang Huating , Wu Wenqing , Chen Yanwen , Guan Ming
Published: September 2021

Background Human chorionic gonadotropin (hCG) detection in cerebrospinal fluid (CSF) can provide additional value in the diagnosis of germinoma. However, matrix effects can influence the results when alternative sample types are used. Therefore, modified-cleared/approved methods, which are standard methods used outside their intended scope, are of interest. The aim of the present study was to establish a model to validate modified-approved methods in agreement with the College of American Pathologists (CAP) accreditation requirements.

Methods Concentrations of hCG in CSF were determined by means of electrochemiluminescence immunoassay using a Roche Cobas e 602 immunoassay analyzer. Based on the intended use, the following performance characteristics were evaluated: precision, the limit of quantitation (LoQ), and the analytical measurement range (AMR). The reference interval (RI) was also established. For the clinical application study, CSF and serum hCG were measured in 10 patients diagnosed with germinoma.

Results The intra- and inter-assay precisions at two levels (10, 250 IU/L) were 0.64 and 0.57% and 4.26 and 3.54%, respectively. The LoQ for hCG was determined to be 0.25 IU/L. The AMR was set from 0.2 to 1,200 IU/L. The RI for hCG in CSF was below 0.40 IU/L. The CSF hCG levels of 10 patients were all above 0.4 IU/L before therapy.

Conclusion Modified-approved methods were validated and showed that the quality specifications of the medical laboratory have a positive value in the clinical context. The illustration of quantification of hCG in CSF resulted in compliance with the CAP accreditation requirements.
A Framework for Systematic Assessment of Clinical Trial Population Representativeness Using Electronic Health Records Data
Authors: Sun Yingcheng , Butler Alex , Diallo Ibrahim , Kim Jae Hyun , Ta Casey , Rogers James R. , Liu Hao , Weng Chunhua
Published: September 2021

Background Clinical trials are the gold standard for generating robust medical evidence, but clinical trial results often raise generalizability concerns, which can be attributed to the lack of population representativeness. The electronic health records (EHRs) data are useful for estimating the population representativeness of clinical trial study population.

Objectives This research aims to estimate the population representativeness of clinical trials systematically using EHR data during the early design stage.

Methods We present an end-to-end analytical framework for transforming free-text clinical trial eligibility criteria into executable database queries conformant with the Observational Medical Outcomes Partnership Common Data Model and for systematically quantifying the population representativeness for each clinical trial.

Results We calculated the population representativeness of 782 novel coronavirus disease 2019 (COVID-19) trials and 3,827 type 2 diabetes mellitus (T2DM) trials in the United States respectively using this framework. With the use of overly restrictive eligibility criteria, 85.7% of the COVID-19 trials and 30.1% of T2DM trials had poor population representativeness.

Conclusion This research demonstrates the potential of using the EHR data to assess the clinical trials population representativeness, providing data-driven metrics to inform the selection and optimization of eligibility criteria.
Uterine Myometrial Preischemia: Yet Another Physiological Change of Pregnancy!
Authors: Jashnani Kusum , Palve Meherrituja
Published: September 2021

Background The uterus shows tremendous increase in size during pregnancy to nurture the fetus within it. It may show a spectrum of physiological changes or pathological lesions that may affect the pregnancy favorably or adversely. The main purpose of our study was to analyze the physiological changes in the uterus during pregnancy and the postpartum period, thereby gaining deeper knowledge.

Materials and Methods We studied a total of 152 uterine specimens obtained from obstetric hysterectomies and maternal autopsies for the presence or absence of normal physiological changes. As a control group, an equal number of surgical uterine specimens received for abnormal uterine bleeding were studied.

Results Decidual change was observed from 6 weeks of gestation to 16 days postpartum. It was partially deficient to absent in four cases of placenta accreta. Myometrial hypertrophy was seen in 150 cases (98.68%) from 8 weeks of gestation till 30 days postpartum period. Vascular remodeling was partially deficient to absent in eight cases of pregnancy-induced hypertension. Preischemia of myometrial fibers was an unexpected finding noticed from 20 weeks of gestation to 16 days postpartum in 131 cases (86.18%). Cervical wall hemorrhages were seen in 84.84% cases of vaginal delivery and in only 17.64% cases of lower segment cesarean section.

Conclusion Ours is the first study to describe the duration of the routine physiological uterine changes during pregnancy. The relationship between cervical wall hemorrhages and vaginal delivery as well as between myometrial preischemia and gestational age, both being normal physiologic findings, was found to be statistically significant.
Quantitative model for impact of behavioral biases on asset allocation decisions: a case study of investors in UAE
Authors: Pradhan Ashutosh
Published: September 2021

Individuals are expected to be rational and follow the approach prescribed under different traditional finance theories while constructing portfolios. In reality, studies from different parts of the world show that individuals do not act rationally due to cognitive limitations and influence of emotions and feelings. Additionally, in quite a few countries, religion plays an important role in decision-making. As a result, individuals make suboptimal decisions, like holding poorly diversified portfolios, excessive or minimal trading, and taking excessive or too little risk with their portfolios. The analysis of impact of behavioral biases and religiosity has not been done in the context of individual investors living in UAE, which this paper addresses. A survey questionnaire was administered to Arab nationals living in UAE. Data of 129 individuals were analyzed. The findings showed that these investors were influenced by emotional and cognitive biases, had good knowledge of religiosity, & placed them as important. This behavior is consistent with investor behavior observed in the rest of the world. Subsequent to these empirical findings, the paper has developed a quantitative model to predict the impact of behavioral biases and religiosity on asset allocation decisions. The research approach used for developing the quantitative model can be replicated by researchers from across the world tailored to their own regions.
Implementation of a non-communicable disease clinic in rural Sierra Leone: early experiences and lessons learned
Authors: Kachimanga Chiyembekezo , Dibba Yusupha , Patiño Marta , Gassimu Joseph S. , Lavallie Daniel , Sesay Santigie , Lado Marta , Kulinkina Alexandra V.
Published: September 2021

This study is an evaluation of the first cohort of patients enrolled in an outpatient non-communicable disease clinic in Kono, Sierra Leone. In the first year, the clinic enrolled 916 patients. Eight months after the enrollment of the last patient, 53% were still active in care, 43% had been lost to follow-up (LTFU) and 4% had defaulted. Of the LTFU patients, 47% only came for the initial enrollment visit and never returned. Treatment outcomes of three patient groups [HTN only (n = 720), DM only (n = 51), and HTN/DM (n = 96)] were analyzed through a retrospective chart review. On average, all groups experienced reductions in blood pressure and/or blood glucose of approximately 10% and 20%, respectively. The proportions of patients with their condition controlled also increased. As NCDs remain underfunded and under-prioritized in low-income countries, the integrated program in Kono demonstrates the possibility of improving outpatient NCD care in Sierra Leone and similar settings.
Toward a ‘New Normal’? Tourist Preferences Impact on Hospitality Industry Competitiveness
Authors: Cuomo Maria Teresa , Tortora Debora , Danovi Alessandro , Festa Giuseppe , Metallo Gerardino
Published: September 2021

The recent outbreak of novel coronavirus (Covid-19) has led to a global panic due to its fatal nature which has harshly impacted the tourist sector and on the place reputation in general. This study aims to compare the factors that develop tourist preferences in terms of (i) what drives the favorability of tourist preferences? (ii) what relationship exists between tourist expectations, proximity, and favorable reputation? and (iii) what are the main influences of tourist preferences on hospitality system competitiveness pre and post Covid-19? By employing structural equation modeling, this study advances knowledge into the research variables’ relationships and advances reputation and marketing performance and practices in the hospitality industry.
Globally conservative solutions for the modified Camassa–Holm (MOCH) equation
Authors: Luo Zhaonan , Qiao Zhijun , Yin Zhaoyang
Published: September 2021

In this paper, we present the globally conservative solutions to the Cauchy problem for the modified Camassa–Holm (MOCH) equation. First, we transform the equation into an equivalent semi-linear system under new variables. Second, according to the standard ordinary differential equation theory with the aid of the conservation law, we give the global solutions of the semi-linear system. Finally, returning to the original variables, we obtain the globally conservative solutions to the MOCH equation.
Review of ultrasonic measurement methods for two-phase flow
Authors: Fan Jinhui , Wang Fei
Published: September 2021

Two-phase flow is commonly used in many aspects of industrial production, such as the mixed transport of oil and gas in petroleum exploitation and the feeding of coal powder or coal water slurry to coal-fired boilers. In these situations, it is necessary to measure the two-phase flow in real time and then adjust various parameters in order to achieve high efficiency, energy-saving, and safe production. The ultrasonic method is widely used to measure two-phase flow because of its various measurement approaches, wide range of measurable parameters, insignificant effect on the flow field, and its capacity for continuous online measurement. In this Review, the principles, characteristics, application scope, and research examples of different ultrasonic methods used in two-phase flow measurement are summarized, their advantages and disadvantages are compared, and the future development trends are forecast, which will play a positive role in the development of two-phase flow measurement.
Controlling the radiative damping of an on-chip artificial magnon mode
Authors: Xu A. Q. , Zhao B. , Yao B. M. , Wang S. W.
Published: September 2021

Controlling magnetic damping lies at the heart of spintronic applications. In particular, manipulating the radiative damping of magnons is important for the emerging dissipative magnon–photon coupling and, therefore, opens up possibilities for advanced hybrid magnonic devices, nonreciprocal transmission, and topological information processing. The materials or structures that produce magnon modes can be further enriched with an artificial magnon mode produced in a complementary electric inductive–capacitive (CELC) resonator due to its flexible tunability, miniaturized size, and easy integration. Here, we explore the radiative linewidth broadening and frequency shifts of a CELC resonator in an on-chip coplanar waveguide in a self-interfering configuration. The radiative dynamics depends on the magnetic component of the local density of photon states, as well as the intensity, polarization, and boundary conditions. In particular, a voltage-controlled phase shifter was integrated to demonstrate voltage-controlled radiative damping. Adopting both the CELC resonator and its complementary structure may be an effective tool for obtaining the spatial distribution of the electric and magnetic components of microwaves. Our work is a general approach to manipulating the radiative damping of magnetic resonance, which has the potential for on-chip functional devices based on dissipative magnon–photon interactions.
High-temperature effect on the sound absorption of cylindrically perforated porous materials
Authors: Liu Xuewei , Xin Fengxian , Zhang Chuanzeng
Published: September 2021

A theoretical model and a finite element (FE) model are proposed to evaluate the effect of high temperature on the sound absorption performance of cylindrically perforated porous materials. The theoretical model is established by applying the double porosity theory, in which the perforated porous material is considered as a combination of the porous material matrix and the cylindrical perforation. The FE model is constructed using the pressure acoustics module of the COMSOL Multiphysics software to verify the theoretical model. In these two models, the temperature effect is accounted for by applying the temperature-dependent physical parameters of the air in the porous material. Several representative examples show that the results obtained by the theoretical model agree well with those obtained by the FE model, and the sound absorption peak moves to higher frequencies as the temperature rises. The analysis of the propagation and dissipation of sound energy at different temperatures shows that the increase in temperature can prevent sound from entering the porous medium, thereby delaying the appearance of the absorption peak along the frequency axis. The perforated porous materials exhibit higher sound absorption performance than traditional homogeneous porous materials and, therefore, have enhanced high-temperature sound absorption potential.
Hysteresis modeling and compensation of a rotary series elastic actuator with nonlinear stiffness
Authors: Zhou Libo , Chen Weihai , Chen Wenjie , Bai Shaoping , Zhao Zheng , Wang Jianhua , Yu Haoyong
Published: September 2021

Series elastic actuators (SEAs) have widely been adapted in robots where safe human–robot interaction is required for accurate and robust force control. Recent research on the SEAs has shown that the SEA with a user-defined variable stiffness possesses several advantages over the constant stiffness SEA, such as large force range and bandwidth while keeping low output impedance and high force fidelity. However, a limitation of this type of SEA is that an obvious hysteresis effect exists and the associated torque curves are nonlinear and vary with amplitudes. Conventional mathematical hysteresis models are usually developed with some kind of black-box modeling, and the model parameters are adjusted through parameter identification methods. It is challenging to tune the model parameters to match the experimental data well among inputs with different amplitudes, let alone the inverse model of the hysteresis, which is necessary to compensate the hysteresis effect in control. In this paper, a rotary SEA (rSEA) with nonlinear stiffness is proposed. A concept called “virtual deformation” is introduced to mathematically transform the nonlinear curve into a polyline hysteresis model. This eases torque estimation with respect to the deformation of the rSEA. A hysteresis compensation torque controller is implemented for precise torque control. A prototype of the rSEA was fabricated, and the experimental results verified modeling accuracy of the proposed model. Our results showed that, with the new model, the computation cost was greatly reduced while keeping the modeling accuracy almost the same compared with the nonlinear backlash model.
Effect of an Ohmic back contact on the stability of Cu(In,Ga)Se2-based flexible bifacial solar cells
Authors: Mavlonov Abdurashid , Nishimura Takahito , Chantana Jakapan , Kawano Yu , Minemoto Takashi
Published: September 2021

In this work, the influence of the Ohmic-contact behavior at the absorber/transparent back-contact interface on the stability of flexible bifacial Cu(In,Ga)Se2 (CIGSe) solar cells is investigated. In the case of the CIGSe/In2O3:SnO2 (ITO) interface, the Ohmic contact is maintained via the introduction of trap-assisted recombination at the CIGSe surface during the ITO deposition. Post-annealed CIGSe/ITO interfaces are studied via time-resolved photoluminescence (TRPL). It is found that the TRPL lifetime of all the samples investigated drastically decreases after the ITO deposition owing to sputtering damage, whereas the TRPL lifetime tends to increase after heat treatment at 160 °C. This increase is attributed to the partial recovery of the sputtering damage during annealing; the increase is larger in samples with less severe sputtering damage than in samples with more severe sputtering damage. Flexible bifacial solar cells with Ohmic-like contact at the CIGSe/ITO interface show superior performance and long-term stability compared with those with non-Ohmic contact at the interface, which may be correlated with the alteration of the metastability during the ITO deposition and/or partial recovery of the sputtering damage. The best flexible bifacial CIGSe solar cells with Ohmic-like back contact show stable performance for over 70 days with efficiencies of 11.1% and 3.0% for the frontside and backside illuminations, respectively.
A compact high-power microwave TM01-TE01 mode converter
Authors: Hu Yong-jun , Xu Liang , Zhang Qiang , Yuan Cheng-wei , Liu Jin-liang , Sun Yun-fei
Published: September 2021

In circular waveguides, the TE01 mode has the lowest transmission loss, which is very suitable for long-distance transmission of high-power microwaves (HPMs). The output mode of HPM sources is mainly the TM01 mode; however, there are few research studies on mode converters of TM01-TE01. In this paper, a high efficiency HPM TM01-TE01 mode converter is designed; compared with the traditional TM01-TE01 mode converters, the structure of the mode converter is compact and easier to process. It is mainly composed of an input circular waveguide, a tapered rectangular waveguide, a 90° bent rectangular waveguide, and an output circular waveguide. A prototype with a center frequency of 2.4 GHz is fabricated and HPM experiments are carried out. The transmission efficiency of this device reaches 99.8% in the simulation, and the measured transmission efficiency is more than 98%. Additionally, the measured power handling capacity is more than 1 GW, which is consistent with simulation. This design has important reference significance for the design of long-distance power transmission devices and HPM mode converters.
Two-color, intracavity pump–probe, cavity ringdown spectroscopy
Authors: Jiang Jun , McCartt A. Daniel
Published: September 2021

We report a proof-of-principle demonstration of intracavity pump–probe, cavity ringdown (CRD) detection in a three-mirror, traveling-wave cavity. With cavity-enhanced pump power and probe absorption path length, the technique is a generally applicable, high-sensitivity, high-selectivity detection method. In our experiments, the pump radiation is switched off during every other probe ringdown, which allows uncorrelated measurements of analyte and background cavity decay rates. The net, two-color signal from the difference between the pump-on and pump-off decay rates is immune to empty-CRD drifts and spectral overlaps from non-target molecular transitions. The immunity to the ringdown drifts allows longer signal-averaging and, thus, higher detection sensitivity. The ability to compensate for the background absorption enhances the detection selectivity in spectrally congested regions. Our technique is well-suited for trace-detection in the mid-IR region, where pump–probe schemes based on strong rovibrational transitions can be applied. In this work, two-color CRD detection is implemented on a ladder-type, three-level system based on the N2O, ν3 = 1 ← 0, P(19) (pump) and ν3 = 2 ← 1, R(18) (probe), rovibrational transitions. By frequency-locking two-quantum cascade lasers to the p-polarization (pump, Finesse = 5280) and s-polarization (probe, Finesse = 67 700) cavity modes, we achieve high intracavity pump power (36 W) and high probe ringdown rates (>2 kHz). The observed two-color spectra are simulated by a density-matrix, three-level system model that is solved under the constraints of the cavity resonance conditions. In addition to its background compensation capability, experimental flexibility in the selection of pump–probe schemes and signal insensitivity to intracavity laser power are further features that enhance the utility of our technique for mid-IR trace-detection.
Water molecules in CNT–Si3N4 membrane: Properties and the separation effect for water–alcohol solution
Authors: Winarto  , Yamamoto Eiji , Yasuoka Kenji
Published: September 2021

Water confined in carbon nanotubes (CNTs) has been intensively studied because of its unique properties and potential for various applications and is often embedded in silicon nitride (Si3N4) membranes. However, the understanding of the influence of Si3N4 on the properties of water in CNTs lacks clarity. In this study, we performed molecular dynamics simulations to investigate the effect of the Si3N4 membrane on water molecules inside CNTs. The internal electric field generated in the CNTs by the point charges of the Si3N4 membrane changes the structure and dynamical properties of water in the nanotubes, causing it to attain a disordered structure. The Si3N4 membrane decreases the diffusivity of water in the CNTs; this is because the Coulomb potential energy (i.e., electrostatic interaction) of water decreases owing to the presence of Si3N4, whereas the Lennard-Jones potential energy (i.e., van der Waals interaction) does not change significantly. Furthermore, electrostatic interactions make the water structure more stable in the CNTs. As a result, the Si3N4 membrane enhances the separation effect of the water–methanol mixture with CNTs in the presence of an external electric field. Furthermore, the threshold of the external electric field strength to induce water–methanol separation with CNTs is reduced owing to the presence of a silicon nitride membrane.
Revealing intrinsic electro-optic effect in single domain Pb(Zr, Ti)O3 thin films
Authors: Kondo Shinya , Yamada Tomoaki , Yoshino Masahito , Teranishi Takashi , Kishimoto Akira , Nagasaki Takanori
Published: September 2021

We deposited polar-axis-oriented tetragonal and rhombohedral single domain Pb(Zr, Ti)O3 (PZT) films on CaF2(100) substrates by inserting SrRuO3 (SRO)/LaNiO3 and SRO/SrTiO3/TiO2/CeO2 buffer layers. Both PZT films grew epitaxially and had a (001)- and (111)-domain with the remnant polarization and piezoelectric constant comparable to the theoretical values of PZT single crystals having the same compositions. The electro-optic (EO) response of the fabricated PZT films was constant with respect to the DC electric field and increased linearly with an increasing AC electric field, thus representing a typical linear EO response in single domain ferroelectrics. The measured EO coefficients were larger than the value for a single crystal of PbTiO3, i.e., one of the end members of PZT, but smaller than the values reported for polycrystalline and epitaxial PZT films with multiple domains. These findings show that the intrinsic EO effect is enhanced in PZT, which is similar to the enhancement seen in the dielectric and piezoelectric constants. Moreover, most of the reported EO response in PZT films is supported by additional extrinsic contributions.
Chaotic dynamics driven by particle-core interactions
Authors: Batygin Konstantin , Batygin Yuri K.
Published: September 2021

High-intensity beams in modern linacs are frequently encircled by diffuse halos, which drive sustained particle losses and result in the gradual degradation of accelerating structures. In large part, the growth of halos is facilitated by internal space-charge forces within the beams, and detailed characterization of this process constitutes an active area of ongoing research. A partial understanding of dynamics that ensue within space-charge dominated beams is presented by the particle-core interaction paradigm—a mathematical model wherein single particle dynamics, subject to the collective potential of the core, is treated as a proxy for the broader behavior of the beam. In this work, we investigate the conditions for the onset of large-scale chaos within the framework of this model and demonstrate that the propensity toward stochastic evolution is strongly dependent upon the charge distribution of the beam. In particular, we show that while particle motion within a uniformly charged beam is dominantly regular, rapid deterministic chaos readily arises within space-charge dominated Gaussian beams. Importantly, we find that for sufficiently high values of the beam's space charge and beam pulsation amplitude, enhanced chaotic mixing between the core and the halo can lead to an enhanced radial diffusion of charged particles. We explain our results from analytic grounds by demonstrating that chaotic motion is driven by the intersection of two principal resonances of the system and derives the relevant overlap conditions. Additionally, our analysis illuminates a close connection between the mathematical formulation of the particle-core interaction model and the Andoyer family of integrable Hamiltonians.
Acoustophoretic patterning of microparticles in a microfluidic chamber driven by standing Lamb waves
Authors: Hsu Jin-Chen , Chao Chih-Lei
Published: September 2021

The contactless manipulation of microparticles and cells by using acoustic forces is important in many applications. However, multi-band acoustophoresis has been rarely investigated in the literature. In this Letter, we propose a microscale acoustofluidic system that has multiple orders of available Lamb modes for the acoustic trapping of microparticles at various frequencies. In our device, standing Lamb waves (SLWs) of specific orders can be selectively excited in a 300-μm-thick piezoelectric lithium-niobate (LiNbO3) crystal plate by a pair of interdigitated transducers (IDTs) at the corresponding frequency. We demonstrate the acoustophoretic trapping and patterning of 7-μm particles in a single acoustofluidic device with multiple available actuating frequencies. The approach to the proposed design and the working mechanisms are explained by using thin plate and a full-wave models that solve the dispersion relations and coupling fields of the piezoelectric SLW acoustofluidic system, respectively. Furthermore, we experimentally show that the stable and tight trapping of particles in the chamber can be achieved independently along two mutually orthogonal directions. This provides the essential ground for planar manipulations of microparticles and cells based on the proposed device. The results here can trigger more innovative designs and applications of acoustofluidic devices for microparticle manipulation and microfluidic mixing, with multi-frequency channels and a wide span of different actuating frequencies in one system.
18O(p,α)15N isotopic tracing of germanium diffusion in SiO2/Si films
Authors: Nélis A. , Vickridge I. , Ganem J.-J. , Briand E. , Terwagne G.
Published: September 2021

We investigate the effects of oxygen on the thermal diffusion of germanium atoms, implanted inside a thermally grown SiO2 layer, during high temperature processes (1100 °C, 60 min). The impact of the presence of oxygen on Ge diffusion is studied as a function of its origin, as it can come either from the annealing atmosphere (extrinsic source) or from the SiO2 matrix itself (intrinsic source). 18O labeling of the oxygen either in the annealing atmosphere or in the silica substrate, together with an isotopically sensitive ion beam analysis, shows a clear oxygen-dependence in germanium diffusion. This is especially so when oxygen is present in the annealing atmosphere, where it is responsible for an enhancement of germanium out-diffusion and redistribution into several peaks during annealing, through the formation of GeO molecules. A new three-process model is proposed to explain the impact of a contaminated atmosphere on the Ge redistribution. This is notably shown that a third Ge peak arises at the sample surface when the annealing atmosphere is contaminated by oxygen. This peak formation is explained by the oxidation of Ge present at the vicinity of the surface by oxygen coming from the annealing atmosphere. This is also shown that O2 molecules can diffuse in depth, with a coefficient of diffusion DO2∼10−9cm2/s, until the densities of Ge and irradiation-induced defects increase, causing the progressive oxidation of Ge in depth and the restoration of the SiO2 stoichiometry.
Biermann battery magnetic fields in ICF capsules: Total magnetic flux generation
Authors: Walsh C. A. , Clark D. S.
Published: September 2021

This paper focuses on the process of magnetic flux generation in inertial confinement fusion implosions. Hot-spots are shown to be dominated by fields generated during stagnation when the temperature and density gradients are largest. A scaling of hot-spot magnetic flux is derived and compared with simulations, revealing that perturbations with both larger amplitudes and higher mode numbers generate more magnetic flux. The model allows for greater understanding of which target designs will be susceptible to magnetohydrodynamic effects. For example, the model can be used to ascertain the time when most magnetic flux is generated. If generation is weighted more toward early times, then more high-mode magnetic field loops will be present. A hot-spot with no high-mode perturbations at time of peak neutron production can still contain significant magnetic flux on those scales. By assuming that magnetic flux is deposited at the hot-spot edge by Nernst advection, the model can be used to post-process radiation-hydrodynamics data to estimate magnetic field strengths and magnetizations.