bluuebunny/crossref_metadata_2025 huggingface dataset:
Alveolar cells in the mammary gland: lineage commitment and cell death
Authors: Watson Christine J.
Published: May 2022

The mammary gland provides a spectacular example of physiological cell death whereby the cells that produce milk during lactation are removed swiftly, efficiently, and without inducing inflammation upon the cessation of lactation. The milk-producing cells arise primarily during pregnancy and comprise the alveolar lineage that is specified by signalling pathways and factors that are activated in response to pregnancy hormones. There are at least two alveolar sub-lineages, one of which is marked by the presence of binucleate cells that are especially susceptible to programmed cell death during involution. This process of post-lactational regression, or involution, is carefully orchestrated and occurs in two phases, the first results in a rapid switch in cell fate with the secretory epithelial cells becoming phagocytes whereupon they destroy dead and dying cells from milk. This reversible phase is followed by the second phase that is marked by an influx of immune cells and a remodelling of the gland to replace the alveolar cells with re-differentiated adipocytes, resulting in a return to the pre-pregnant state in preparation for any subsequent pregnancies. The mouse mammary gland provides an excellent experimental tool with which to investigate lineage commitment and the mechanisms of programmed cell death that occur in a normal physiological process. Importantly, involution has highlighted a role for lysoptosis, a mechanism of cell death that is mediated by lysosomal cathepsins and their endogenous inhibitors, serpins. In this review, I discuss alveolar lineage commitment during pregnancy and the programmed cell death pathways that destroy these cells during involution.
Identification of the target and mode of action for the prokaryotic nucleotide excision repair inhibitor ATBC
Authors: Bernacchia Lorenzo , Paris Antoine , Gupta Arya , Moores Alexandra A. , Kad Neil M.
Published: May 2022

In bacteria, nucleotide excision repair (NER) plays a major role in repairing DNA damage from a wide variety of sources. Therefore, its inhibition offers potential to develop a new antibacterial in combination with adjuvants, such as UV light. To date, only one known chemical inhibitor of NER is 2-(5-amino-1,3,4-thiadiazol-2-yl)benzo(f)chromen-3-one (ATBC) exists and targets Mycobacterium tuberculosis NER. To enable the design of future drugs, we need to understand its mechanism of action. To determine the mechanism of action, we used in silico structure-based prediction, which identified the ATP-binding pocket of Escherichia coli UvrA as a probable target. Growth studies in E. coli showed it was nontoxic alone, but able to impair growth when combined with DNA-damaging agents, and as we predicted, it reduced by an approximately 70% UvrA’s ATPase rate. Since UvrA’s ATPase activity is necessary for effective DNA binding, we used single-molecule microscopy to directly observe DNA association. We measured an approximately sevenfold reduction in UvrA molecules binding to a single molecule of dsDNA suspended between optically trapped beads. These data provide a clear mechanism of action for ATBC, and show that targeting UvrA’s ATPase pocket is effective and ATBC provides an excellent framework for the derivation of more soluble inhibitors that can be tested for activity.
Validity and Reliability of the Turkish Version of the Sydney Swallow Questionnaire
Authors: Atar Sevgi , Atar Yavuz , Ilgin Can , Uygan Ugur , Demirhan Esma , Anarat Melis Ece Arkan , Tutar Belgin , Sari Hüseyin , Berkiten Güler , Kuru Ömer
Published: May 2022

Purpose:

This study aimed to assess the validity and reliability of the Turkish version of the Sydney Swallow Questionnaire (SSQ-T) and calculate a cutoff value to help clinicians to suspect/predict oropharyngeal dysphagia (OPD).

Method:

The original questionnaire was translated into Turkish by two bilingual English Turkish translators. The study included 170 Turkish adult subjects. Half of the participants were patients presenting with OPD, and half were healthy controls. Fiberoptic endoscopic evaluation of swallowing (FEES) was administered to all subjects. Patients were evaluated using the Turkish Penetration Aspiration Scale and the Yale Pharyngeal Residue Severity Rating Scale. Additionally, the final version of the SSQ-T questionnaire and the Turkish Eating Assessment Tool were administered to all subjects.

Results:

Internal consistency was high on all questions (Cronbach's α = .974). Test–retest reliability was also high (intraclass correlation coefficient = .975,
p
< .001; 95% confidence interval [.948–.988]). The SSQ-T score range was 0–1,240 for all participants, 57–1,240 for the patients with OPD, and 0–152 for the healthy controls. The cutoff value was 174 with 85.96% sensitivity and 99.12% specificity.

Conclusion:

The SSQ-T was demonstrated to be a valid and reliable assessment to assess the self-perceived severity of OPD.
Multi‐user underwater acoustic communication using binary phase‐coded hyperbolic frequency‐modulated signals
Authors: Zuberi Habib Hussain , Liu Songzuo , Sohail Muhammad Zohaib , Pan Chenyu
Published: May 2022

Multi‐user communication traditionally uses either code division multiple access (CDMA) or time‐division multiple access schemes. The chirp signals resilience to multipath and the Doppler effect makes it suitable for underwater acoustic communication. This paper presents a binary phase‐coded hyperbolic frequency‐modulated (BPC‐HFM) for multi‐user underwater acoustic communication. The proposed scheme has the advantage of both linear frequency‐modulated signal, which is immune to multipath and Doppler offset, while PN sequence is encoded in such a manner that a waveform possesses either a phase shift of 0 or 180 depending upon the code which results in a unique orthogonal waveform for every user. As a result, it helps to reduce multiple access interference; in addition, the time‐reversal mirror technique is used to enhance the performance of the system in the high multipath environment due to the virtue of hydro‐acoustic channel. Furthermore, it uses a relatively simple matched filter‐based receiver. To substantiate the robustness of the proposed multi‐user waveforms three types of hydro‐acoustic channels using the different numbers of multiple users are chosen for simulation and the bit error rate (BER) of the system is calculated. Furthermore, the results are compared to binary phase‐coded linear frequency‐modulated signal and conventional Direct sequence spread spectrum CDMA.
A novel wideband radar detector via Wiener filter
Authors: Ma Weijie , Tu Guoyong , Deng Zhenmiao , Lu Xiaofei , Ye Yishan , Li Yuhan
Published: May 2022

To minimise the noise interference in the radar received echoes and optimise the detection issue for a wideband radar system, a novel wideband radar track‐before‐detect detector via Wiener Filter is proposed. The Wiener Filter can effectively remove the noise mixed in the echoes and make the filtered signal consistent with the original signal. After applying maximum likelihood estimation to the echoes, the authors can reconstruct the desired signal required for Wiener filtering by extracting the range information of each scatterer. Then Wiener Filtering is performed on the echo containing noise with the desired signal to complete the denoising. Subsequently, we exploit the correlation between the adjacent echoes for detection. The effectiveness of the detector can be verified by the numerical simulation results of synthetic and real radar data. The proposed detector is superior to the waveform contrast detector, inter‐period correlation processor and modified correlation matrix detector.
Day‐ahead flexibility market clearing mechanism for interactive collaboration of transmission and distribution system operators
Authors: Talaeizadeh Vali , Aghaei Jamshid , Shayanfar Heidarali
Published: May 2022

This paper explores the procurement of flexibility services in the power system by the collaboration between transmission system operators (TSO) and distribution system operators (DSO) in the day‐ahead market (DAM). With the coordination and interaction among the operators, the existing flexibility sources in transmission and distribution levels are exploited efficiently to procure flexibility services. For motivation of the distributed generation (DGs) sources and microgrids (MGs) to provide flexibility services, DSO aggregates the flexible sources of its grid and offers them to the upstream market. Doing so addresses the TSO uncertainties and improves the flexibility of the entire grid. The simulation results suggest the increased market efficiency and reduced operating costs for transmission and distribution levels using flexible sources. Furthermore, the results demonstrate that utilization of existing flexible sources in the distribution grid enhances the flexibility of the entire system and, consequently, increases the absorption from renewable energy sources (RES). Also, the flexibility procurement for DSO is associated with an increase in revenue and motivation of MGs. An examination of the impact of MG's ownership on the market clearing mechanism is also investigated in this regard. Finally, the reserve affects the system's flexibility. This effect is helpful for flexible systems while reducing the flexibility metrics for inflexible systems.
A novel energy management framework incorporating multi‐carrier energy hub for smart city
Authors: Esapour Khodakhast , Moazzen Farid , Karimi Mazaher , Dabbaghjamanesh Morteza , Kavousi‐Fard Abdollah
Published: May 2022

The development of advanced and intelligent measurement instruments in recent years has increased the intelligence of modern energy systems, especially power systems. Besides, with the advancement of energy conversion technologies, these systems benefit from multi‐carrier energy resources. Accordingly, this paper presents a model of smart city which considers various components, including smart transportation system (STS), microgrid (MG), and smart energy hub (SEH) with the ability of energy transformation. The proposed model addresses the islanded operation of a smart city that makes it a smart island. This island deploys the energy carriers of electricity, heat, gas and water as well. In addition, STS includes electric vehicle (EV) parking lots as well as metro system (MS) that can interactively exchange energy. More precisely, the different components of the smart island are modelled on the assumption of energy interdependency. In the proposed model, the water supply unit in SEH is provided which can be effective in reducing the cost of components by supplying water to them. In order to exchange energy within STS, metro stations have been optimally allocated using intelligent water drops (IWD) optimization method. In addition to smart island modelling, this paper quantifies the uncertainties within STS and MG using cloud theory. Eventually, the proposed model is simulated to ensure its effectiveness and accuracy.
Attention‐based multi‐scale feature fusion for free‐space detection
Authors: Song Pengfei , Fan Hui , Li Jinjiang , Hua Feng
Published: May 2022

Free space detection is a very important task in road scene understanding. With the continued development of convolutional neural networks, free‐space detection can be seen as a class‐specific semantic segmentation problem. In this paper, a new encoding–decoding network structure‐HRUnet is designed, which always maintains the input of high‐resolution images in both the encoding and decoding phases. It extracts multi‐scale information from RGB images and continuously fuses them, and finally achieves accurate spatial detection. In addition, in order to improve the accuracy of detection, the attention mechanism module‐spin attention is proposed to achieve the interaction between channel and spatial dimensions when calculating channel attention, establish the come relationship between channel and space, reduce the loss of feature information, and further improve the accuracy of spatial detection. Experimental results show that the proposed neural network structure outperforms current popular models in terms of balanced the computational complexity and accuracy.
Wideband single‐layer patch antenna with stable high gain using characteristic mode analysis
Authors: Gao Kun , Cao Xiangyu , Li Tong , Yang Huanhuan , Li Si Jia , Gao Jun
Published: May 2022

A low‐profile single‐layer patch antenna is proposed for bandwidth enhancement and stable high gain simultaneously. Firstly, coplanar parasitically coupled patches are introduced on two edges of the main driven patch to generate new resonant modes. The mutual compensation of modal electric energy and magnetic energy and the combination of modes lead to wideband performance based on characteristic mode analysis (CMA). Secondly, due to odd mode with unstable gain at high frequency, metallised vias are installed in the parasitic patches. Therefore, the symmetrical TM01 mode of parasitic patches is reshaped to the TM10 mode, and three in‐phase TM10 modes are connected in parallel to generate stable high gain. The CMA is utilised to guide the transformation of unwanted modal behaviours into desired modal states. The achieved impedance bandwidth for −10 dB is 13.7% (4.96–5.69 GHz) with a gain of 6.86–8.53 dBi over the operating bandwidth.
Study on the complexity of channel pricing game in showrooming O2O supply chain
Authors: Li Yaping , Ma Junhai , Liu Yuxin
Published: May 2022

An O2O supply chain consisting of a manufacturer with an online direct channel and a retailer who resells through a brick-and-mortar store is considered. Three channel power structures (vertical Nash, manufacturer Stackelberg, and retailer Stackelberg) and three pricing sequences (simultaneous pricing, manufacturer pricing early, retailer pricing early) are considered. Counter-intuitively, under the manufacturer Stackelberg structure, the retailer has a first-mover advantage and retailer-pricing-early achieves Pareto optimality. In the other cases, the manufacturer and the retailer have a late-mover advantage. Under the vertical Nash structure, both parties may get into a prisoner’s dilemma. Extending the basic model to dynamic pricing, we found that the first mover of sequential pricing has better stability. The retailer Stackelberg structure has better stability than the vertical Nash structure and the manufacturer Stackelberg is the most unstable power structure. To avoid the negative impact of equilibrium price instability, the vertical and horizontal price matching mechanisms are proposed and the effectiveness in improving stability is proved.
Homöopathie als komplementäre Therapie bei genuiner Myopathie – ein Fallbeispiel
Authors: von Kriegsheim Ada
Published: May 2022

In diesem Fallbericht wird ein Hund mit einer genuinen Myopathie beschrieben. Die Behandlung erfolgt schulmedizinisch mit Mestinon und komplementär letztendlich mit Phosphorus. Über 3 Jahre
hat Robbi viel Kraft in seiner Muskulatur und kann trotz der Erkrankung lange Spaziergänge tätigen. Am Ende erliegt dieser sympathische Hund einem Osteosarkom.

Es wird der Mittelübergang von Causticum zu Phosphorus diskutiert, ein Augenmerk auf die komplementäre Therapie gelegt und der Knochenkrebs mit der Erkrankung ins Verhältnis gesetzt.
Prevalence and Predictors of Pediatric COVID-19 Vaccine Acceptance
Authors: Bourque Stephanie L. , Weikel Blair W. , Palmer Claire , Cataldi Jessica R. , Blackwell Sarah , Hwang Sunah S.
Published: May 2022

Objective As pediatric COVID-19 vaccine eligibility expands, understanding predictors of vaccine intent is critical to effectively address parental concerns. Objectives included: (1) Evaluate maternal COVID-19 vaccine intent for child(ren) and associated predictors of stated intent; (2) Describe attitudes related to hypothetical vaccination policies; (3) Summarize themes associated with intention to vaccinate child(ren) for COVID-19.

Study Design Mothers enrolled in Heath eMoms, a longitudinal survey project, were recruited for this electronic COVID-19 survey. Chi-square analysis was used to compare proportions of respondent characteristics based on vaccination intent. Population survey logistic regression was used for multivariable modeling to assess the independent association between vaccine intent and demographics.

Results The response rate was 65.3% (n = 1884); 44.2% would choose vaccination, 20.3% would not choose vaccination, and 35.5% are unsure whether to have their child(ren) vaccinated for COVID-19. Black mothers (AOR 0.26, 95% CI 0.13, 0.54), respondents with less than high school education (AOR 0.26, 95% 0.12, 0.56) and those in rural areas (AOR 0.28, 95% CI 0.16, 0.48) were less likely to choose vaccination. Commonly cited reasons for vaccine hesitancy include the belief that the vaccine was not tested enough, is not safe, and there are concerns regarding its side effects.

Conclusion Over 50% of respondents do not intend or are unsure about their intent to vaccinate their child(ren) for COVID-19 with variability noted by demographics. Opportunities exist for perinatal and pediatric providers to educate pregnant people, parents, and caregivers with a focus on addressing concerns regarding vaccine safety and efficacy.

Key Points
Educational Impact of Targeted Neonatal Echocardiography and Hemodynamics Programs on Neonatal-Perinatal Medicine Fellows
Authors: Friedmann Isabel , McNamara Patrick J. , Bhattacharya Soume , Cheng Anita
Published: May 2022

Objective Targeted neonatal echocardiography (TNE) is a real-time cardiac imaging modality used by a hemodynamics program to aid in diagnosis, treatment, and monitoring of neonatal cardiovascular illness. This study aimed to describe trainees' perspectives on existing hemodynamics education and perceived impacts of TNE and hemodynamics services on their education.

Study Design This was a mixed quantitative and qualitative study that surveyed neonatal-perinatal medicine (NPM) fellow trainees in Canada and the United States, at programs both with and without a hemodynamics service.

Results Ninety-two fellows responded to the survey, of whom 24 (26%) were enrolled in a program with an active hemodynamics service, 64 (70%) were training at a program without a hemodynamics service, and 4 (4%) were unsure. Trainees at centers with a hemodynamics service were more satisfied with their cardiovascular physiology education (91 vs. 69%, p = 0.040). Twenty-five percent of all trainees felt they do not have sufficient hemodynamics training to prepare them for independent practice. Areas of knowledge gaps were identified. Bedside teaching combined with didactic teaching was identified as useful means of teaching.

Conclusion Most trainees believed that TNE and a hemodynamics service are valuable educational assets. Thoughtful curriculum design for real-time and consolidation learning, with specific emphasis on content gaps, should be considered.

Key Points
Should Fathers Also Do Kangaroo Care?
Authors: Yaman Akan , Kandemir İbrahim , Özek Eren , Bilgen Hülya Selva
Published: May 2022

Objectives The aim of the study is to compare the effect of maternal and paternal Kangaroo care (KC) on vital signs and cerebral oxygen saturation (rSO2) parameters.

Methods This randomized study included 35 preterm infants born at 32 weeks gestation or earlier. The body temperature, respiratory rate, heart rate, oxygen saturation (sPO2), and cerebral oxygen saturation (rSO2) were measured at the postnatal 35th week of gestation during three periods: in the incubator before KC, during KC with the mother or father, and in the incubator after KC. The measured parameters of the three periods were compared within each group (mother or father) and between the groups (mother and father).

Results There was no statistically significant difference between the vital signs during the three periods, both in the mother and father groups, and between the parents.

The rSO2 values increased significantly in both parents (p <0.001) during and after KC. When we compared parents, rSO2 values were significantly higher during (p = 0.015) and after (p = 0.046) mother KC.

Conclusion The difference between M-KC and F-KC can be ignored as the cerebral near infra-red spectroscopy values are within normal limits. The active participation of fathers in KC should be encouraged by health professionals in all NICUs.

Key Points
Palladium-Catalyzed Cross-Coupling of Cyanohydrins with Aryl Bromides: Construction of Biaryl Ketones
Authors: Dai Huifang , Evans P. Andrew , Majhi Jadab , Zhou Bohang , Zhuang Yuxin , Tom Mai-Jan
Published: May 2022

The palladium-catalyzed cross-coupling of the lithium anion of aryl tert-butyldimethylsilyl-protected cyanohydrins with aryl bromides followed by in situ deprotection with fluoride ion provides a convenient and versatile approach to biaryl ketones. This protocol represents the first example of a palladium-catalyzed arylation of a cyanohydrin, which functions as an acyl anion equivalent. Hence, in contrast to classical cross-coupling reactions, the pronucleophile component is incorporated in the product to permit further functionalization. We then highlight the synthetic utility of the new method with applications to bioactive biaryl ketones and the construction of a triaryl diketone that has been used to prepare an extended tetrathiafulvalene.
Changes, Challenges, and Variations in Neonatal-Perinatal Medicine Fellowship: A View from the Program Directors
Authors: Gray Megan M. , Bruno Christie , French Heather , Myers Patrick , Carbajal Melissa M. , Reber Kristina M. , Christou Helen , Karpen Heidi , Johnston Lindsay C. ,   on behalf of the Organization of Neonatal-Perinatal Medicine Training Program Directors
Published: May 2022

Objectives Neonatal-perinatal medicine (NPM) fellowship programs in the United States support >800 learners annually. Understanding variations in the programmatic structure, challenges, and needs is essential to optimize the educational environment and ensure the specialty's future.

Study Design NPM fellowship program directors (PDs) and associate program directors (APDs) were invited to complete an electronic survey on their program administration, recruitment, clinical training, assessment methods, scholarly program, and career pathways. Each participant identified individual programmatic strengths, challenges, opportunities, and threats to the field.

Results Representatives from 59 NPM fellowships provided data (response rate 59/96 = 61%). In total, 30% of PDs received less than the Accreditation Council for Graduate Medical Education -recommended protected time for administrative duties, and 44% of APDs received no protected time. Fellow clinical service assignments varied widely from 13 to 18 months and 90 to 175 call nights over 3 years. Recruitment practices varied across programs; 59% of respondents raised concerns over the pipeline of applicants. Conflicts between fellows and advanced practice providers were identified by 61% of responders. Programs varied in their scholarly offerings, with 44% of NPM fellowships interested in adding broader research opportunities.

Conclusion NPM fellowship leaders identified a need for improved programmatic support, enhanced measures to assess competency, opportunities to strengthen scholarly programs, shared curricular resources, and strategies to balance education with clinical demands. PDs and APDs identified threats to the future of NPM training programs including the diminishing pipeline of applicants into neonatology, challenges with clinical exposure and competence, inadequate support for the educational mission, issues supporting high-quality scholarship, and fewer graduates pursuing physician-investigator pathways. National organizations and academic institutions should take action to address these challenges so that fellowships can optimally prepare graduates to meet their patients' needs.

Key Points
Reduced Bone Mineral Density in Middle-Aged Male Patients with Adult
Growth Hormone Deficiency
Authors: Liu Shanshan , Yang Hongbo , Xu Hanyuan , Zhou Zhibo , Bai Xi , Wang Linjie , Duan Lian , Gong Fengying , Zhu Huijuan , Pan Hui
Published: May 2022

The aim of the work was to investigate the bone mineral density (BMD) in
middle-aged male patients with both childhood-onset (CO) and adulthood-onset
(AO) adult growth hormone deficiency (AGHD). In this retrospective
cross-sectional study in a major medical center in China, dual X-ray
absorptiometry was performed in 50 male AGHD patients (average age was
35.2±9.8 years) and 50 age- and BMI-matched non-athletic healthy men.
BMD was compared between AGHD patients and controls. Compared with healthy
controls, AGHD group had significantly decreased IGF-1 (p1<0.001) and
IGF-1 SDS (p1<0.001). Serum testosterone levels were significantly lower
in AGHD patients (p1<0.001), mainly in AO AGHD patients
(p3<0.001). The BMD of the femoral neck, trochanter, femoral shaft,
total hip, and lumbar spine were significantly lower in all AGHD patients
compared with healthy controls (all p1<0.05), especially in CO AGHD
patients (all p2<0.05). Multiple stepwise linear regression indicated
AGHD was negatively correlated with BMD at each site (β<0,
p<0.05). Additionally, serum testosterone level was an independent
influencing factor of BMD of the femoral neck (β=0.256,
p=0.018) and lumbar spine (β=0.219, p=0.040).
BMD was significantly reduced in AGHD patients, especially in CO AGHD patients.
Our data suggested that the status of growth hormone deficiency and testosterone
level were important for maintaining of bone mineral density in middle-aged male
patients with AGHD.
Necrotizing Enterocolitis in Very Low Birth Weight Neonates: A Natural History Study
Authors: Mara Kristin C. , Clark Reese H. , Carey William A.
Published: May 2022

Objective We characterize the most recent natural history of necrotizing enterocolitis (NEC), as this is an essential first step in guiding the prevention and treatment of this disease in the present day.

Study Design We performed a retrospective cohort study of neonates who were born at 23 to 29 weeks' gestation and birth weight <1,500 g who received care from the Pediatrix Medical Group between 2004 and 2019. We assessed the incidence of medical and surgical NEC and the patterns of initial antibiotic treatment to develop a contemporary cohort for further analysis. Among patients discharged between 2015 and 2019, we characterized the stage-specific risk factors for patients diagnosed with medical or surgical NEC, as well as patterns of disease onset, progression, biomarkers, and outcomes. We used the same approach to characterize patients diagnosed with suspected NEC.

Results Among 34,032 patients in the contemporary cohort, 1,150 (3.4%) were diagnosed with medical NEC and 543 (1.6%) were diagnosed with surgical NEC. The temporal pattern of disease onset was different for medical and surgical NEC, with gestational age– and birth weight–specific risk disparities emerging earlier in surgical NEC. Thirty-day mortality was much greater among surgical NEC patients (medical NEC 16.4% vs. surgical NEC 43.0%), as were rates of various in-hospital and long-term outcomes. Suspected NEC was diagnosed in 1,256 (3.7%) patients, among whom risk factors and disease onset, progression, and outcomes closely resembled those of medical NEC.

Conclusion Analyzing data from a contemporary cohort enabled us to characterize the current, stage-specific natural history of NEC, including novel insights into suspected NEC. Future studies could leverage this cohort to characterize how specific patient characteristics, care processes, or biomarkers may influence or predict disease outcomes.

Key Points
Investigating the effect of vocational education and training on rural women’s empowerment
Authors: Ebrahimi R. , Choobchian S. , Farhadian H. , Goli I. , Farmandeh E. , Azadi H.
Published: May 2022

This research is an attempt to identify the most important dimensions of vocational education and training (VET) on empowering rural women, a topic that has received less attention. The present study is a quantitative, non-experimental, applied, survey research, whose statistical population includes rural women and girls who participated in VET classes. The research tool was a researcher-designed questionnaire. The reliability and validity of the research tool using a pilot test and calculating Cronbach’s alpha, AVE, and CR coefficients were shown to indicate the high capability of the research tool to collect data. The results showed that among the four dimensions of VET, the role of content and educator was more than other dimensions and these dimensions of training had improved the economic empowerment of rural women, which was often at the lowest level. The conceptual framework presented can be used as a guide to achieving sustainable development goals of the millennium; and should be considered at the national and international levels. The paper makes an impact on the growing body of knowledge by emphasizing on more important dimensions of education; which can be effective for the empowerment of women, especially in the economic dimension. In the existing studies on empowering rural women, none of them examined the effect of all different components of education on women’s overall empowerment, which are among the innovations of the present study and should be considered in future planning.
Multistep molecular and macromolecular assembly for the creation of complex nanostructures
Authors: Yang Dong , Sasaki Norihiko , Shimada Takuma , Jin Zhehui , Takeuchi Masayuki , Sugiyasu Kazunori
Published: May 2022

In this short review, we provide an overview of multistep molecular and macromolecular assembly in syntheses of higher-order structures that are unobtainable under thermodynamic control. As in the case of organic/macromolecular chemistry, a synthetic scheme is designed such that a series of assembly processes eventually leads to a complex structure. The recent progress in this research field has been made based on the mechanistic understandings from viewpoints of both thermodynamics and kinetics. We also describe relevant systems which make use of advanced experimental apparatuses such as optical tweezers, high-speed atomic force microscopy, and so on. The unprecedented structures obtainable in this way might play a pivotal role in bridging the hierarchical levels from the molecular scale to the macroscopic world, leading to new functional supramolecular materials.
Time-resolved vibrational-pump visible-probe spectroscopy for thermal conductivity measurement of metal-halide perovskites
Authors: Li Shunran , Dai Zhenghong , Li Linda , Padture Nitin P. , Guo Peijun
Published: May 2022

Understanding thermal transport at the microscale to the nanoscale is crucially important for a wide range of technologies ranging from device thermal management and protection systems to thermal-energy regulation and harvesting. In the past decades, non-contact optical methods, such as time-domain and frequency-domain thermoreflectance, have emerged as extremely powerful and versatile thermal metrological techniques for the measurement of material thermal conductivities. Here, we report the measurement of thermal conductivity of thin films of CH3NH3PbI3 (MAPbI3), a prototypical metal-halide perovskite, by developing a time-resolved optical technique called vibrational-pump visible-probe (VPVP) spectroscopy. The VPVP technique relies on the direct thermal excitation of MAPbI3 by femtosecond mid-infrared optical pump pulses that are wavelength-tuned to a vibrational mode of the material, after which the time dependent optical transmittance across the visible range is probed in the ns to the μs time window using a broadband pulsed laser. Using the VPVP method, we determine the thermal conductivities of MAPbI3 thin films deposited on different substrates. The transducer-free VPVP method reported here is expected to permit spectrally resolving and spatiotemporally imaging of the dynamic lattice temperature variations in organic, polymeric, and hybrid organic–inorganic semiconductors.
Flexible perovskite solar cells: Material selection and structure design
Authors: Xu Yumeng , Lin Zhenhua , Zhang Jincheng , Hao Yue , Ouyang Jianyong , Liu Shengzhong , Chang Jingjing
Published: May 2022

With the rapid development of the Internet of Things, convenient and portable self-powered devices are in great need. Among all substitutes that could provide clean and sustainable power, the flexible perovskite solar cells (FPSCs) are the most attractive with the characteristics of flexibility, lightweight, high power conversion efficiency, and low cost. In this review, the recent advances of FPSCs are summarized, focusing on the materials' assessment of flexible and durable substrate, transparent electrode, low-temperature processed charge transporting layer, and mechanically robust perovskite film, with device design interspersed in each part. Finally, the challenges of FPSCs in terms of higher efficiency, higher flexibility, higher stability, and scalable fabrication are summarized.
External charge compensation in etched gallium nitride measured by x-ray photoelectron spectroscopy
Authors: Hatch Kevin A. , Messina Daniel C. , Fu Houqiang , Fu Kai , Zhao Yuji , Nemanich Robert J.
Published: May 2022

Electronic states at GaN surfaces and at regrowth and heteroepitaxy interfaces inhibit electronic device performance. Understanding electronic state configuration at the GaN surface is, therefore, crucial for the development of GaN-based devices, which are currently of considerable interest in power electronic applications. GaN and other wurtzite III-nitrides possess large spontaneous polarization along the c-axis, producing a bound sheet charge at the surface, which affects the electronic state configuration through the formation of internal and external compensation charges. Defects induced by conventional plasma-based dry etching methods may inhibit the internal screening of this bound charge and thus increase the concentration of external charged states. The surface band bending of n-type Ga-face GaN (0001) was measured with x-ray photoelectron spectroscopy after inductively coupled plasma etching to investigate the impact of dry etching on external charge compensation. GaN samples were etched using inductively coupled plasma with varying rf power and a novel plasma-enhanced atomic layer etching method using an oxidation, fluorination, and ligand-exchange mechanism. The band bending varied from 0.0 to 0.8 ± 0.1 eV for the samples measured.
Large magnetocaloric effect of Tm1 − xYxGa (0 ≤ x ≤0.8) compounds with second-order magnetic transition around liquid helium temperature
Authors: Yang S. X. , Zheng X. Q. , Xi L. , Wang D. S. , Liu C. F. , Xu J. W. , Shen J. X. , Wang L. C. , Xu Z. Y. , Zhang J. Y. , Wang S. G. , Shen B. G.
Published: May 2022

A systematic investigation about Tm substitution by rare earth Y atoms in Tm1 − xYxGa (0 ≤ x ≤0.8) compounds on the magnetic properties and magnetocaloric effect (MCE) is presented. Among Tm1 − xYxGa compounds, Tm0.4Y0.6Ga exhibits the optimized working temperatures around the boiling point of liquid helium and large MCE. It undergoes a ferromagnetic (FM) to antiferromagnetic (AFM) transition at TFA = 2.8 K and an AFM to paramagnetic transition at TN = 5.4 K with increasing temperature, respectively. Moreover, the characteristic of second-order magnetic transition was confirmed on the basis of Arrott plots, rescaled universal curves, mean-field theory criterion, and the quantitative criterion of exponent n. Large MCE with the maximum magnetic entropy change of 6.4, 10.1, and 15.6 J/kg K and the maximum adiabatic temperature change of 2.4, 4.2, and 8.4 K for the field changes of 0–1, 0–2, and 0–5 T was observed, respectively. Consequently, the properties of low working temperatures, the characteristic of second-order magnetic transition, and good performance of MCE indicate that Tm0.4Y0.6Ga compounds could be a promising candidate of magnetocaloric materials in the application of helium liquefaction.
Controllable growth of large-area 1T′, 2H ultrathin MoTe2 films, and 1T′–2H in-plane homojunction
Authors: Li Jiacheng , Gao Hui , Zhou Guoliang , Li Yan , Chai Ye , Hao Guolin
Published: May 2022

Atomically thin molybdenum ditelluride (MoTe2) has been intensively studied as an emerging material for electronics and optoelectronics due to its unique properties. While the small free energy difference between the 2H and 1T′ phases of MoTe2 always results in mixed-phase growth, precisely controlled phase transition of MoTe2 nanostructures is still a considerable challenge. Here, the centimeter-scale 1T′, 2H ultrathin MoTe2 films, and in-plane 1T′–2H homojunction have been synthesized by ambient pressure chemical vapor deposition based on the precursor design and space-confined strategies. The controllable growth of pure 1T′, 2H MoTe2, and 1T′–2H mixed-phase MoTe2 with phase separation and homogeneous mixture, respectively, has been achieved by adjusting growth temperature and growth time. The thickness of synthesized 1T′ and 2H ultrathin MoTe2 films can be effectively controlled by tuning the space-confined height. The corresponding growth mechanism was further illuminated based on systematically experimental characterizations and computational fluid dynamics simulations. The electrical transport properties of 1T′ and 2H MoTe2 films were investigated by conductive atomic force microscope and MoTe2-based thin-film field-effect transistors. Our experimental results provide a new route to realize the phase transition of two-dimensional materials, which makes these materials easily accessible as functional building blocks for next-generation electronic and optoelectronic devices.
Robust large-area elastic transverse wave transport in active acoustic metamaterials
Authors: Chen Zhenyu , Wang Xiangyu , Lim C. W. , Shi Fan
Published: May 2022

We investigate robust large-area elastic transverse wave propagation in an actively tunable membrane-type acoustic metamaterial. The waveguide with multiple degrees of freedom to control the width of the interface mode is realized by designing a heterostructure including three domains. One central domain is constructed by periodic unit cells in an ordinary state, where a Dirac cone can be observed in the band structure. The other two domains consist of periodic unit cells possessing opposite valley Chern numbers, respectively. By employing a finite element model, the topologically protected interface states with tunable degrees of freedom are exhibited. The energy of interface states distributes equally in the large-central region. Although a larger degree of freedom leads to lower amplitudes of interface states, larger total energy is demonstrated by defining a quality factor. Moreover, we design several waveguides with straight lines and sharp corners with different angles and denote three different notations to show clearly that the large-area transverse wave can propagate robustly through sharp corners. Finally, it is found that the large-area transverse wave transport shows immunity to disorders and defects in the propagation path.
Core–hole delocalization for modeling x-ray spectroscopies: A cautionary tale
Authors: Brumboiu Iulia Emilia , Fransson Thomas
Published: May 2022

The influence of core–hole delocalization for x-ray photoelectron, x-ray absorption, and x-ray emission spectrum calculations is investigated in detail using approaches including response theory, transition-potential methods, and ground state schemes. The question of a localized/delocalized vacancy is relevant for systems with symmetrically equivalent atoms, as well as near-degeneracies that can distribute the core orbitals over several atoms. We show that the issues relating to core–hole delocalization are present for calculations considering explicit core–hole states, e.g., when using a core-excited or core-ionized reference state or for fractional occupation numbers. As electron correlation eventually alleviates the issues, but even when using coupled-cluster single-double and perturbative triple, there is a notable discrepancy between core-ionization energies obtained with localized and delocalized core–holes (0.5 eV for the carbon K-edge). Within density functional theory, the discrepancy correlates with the exchange interaction involving the core orbitals of the same spin symmetry as the delocalized core–hole. The use of a localized core–hole allows for a reasonably good inclusion of relaxation at a lower level of theory, whereas the proper symmetry solution involving a delocalized core–hole requires higher levels of theory to account for the correlation effects involved in orbital relaxation. For linear response methods, we further show that if x-ray absorption spectra are modeled by considering symmetry-unique sets of atoms, care has to be taken such that there are no delocalizations of the core orbitals, which would otherwise introduce shifts in absolute energies and relative features.
Nondestructive microstructural investigation of defects in 4H-SiC epilayers using a multiscale luminescence analysis approach
Authors: El Hageali Sami A. , Guthrey Harvey , Johnston Steven , Soto Jake , Odekirk Bruce , Gorman Brian P. , Al-Jassim Mowafak
Published: May 2022

The development of metal oxide semiconductor field effect transistors (MOSFETs) utilizing epitaxially grown 4H-SiC has accelerated in recent years due to their favorable properties, including a high breakdown field, high saturated electron drift velocity, and good thermal conductivity. However, extended defects in epitaxial 4H-SiC can affect both device yields and operational lifetime. In this work, we demonstrate the importance of a multiscale luminescence characterization approach to studying nondestructively extended defects in epitaxial 4H-SiC semiconducting materials. Multiscale luminescence analysis reveals different aspects of excess charge carrier recombination behavior based on the scale of a particular measurement. Combining measurements of the same extended defect area at different scales tells us more about the essential nature of that defect and its microstructure. Here, we use photoluminescence imaging and cathodoluminescence spectrum imaging to investigate the recombination behavior of several different types of extended defects, including stacking faults, inclusions, and basal plane dislocations. A detailed understanding of the optoelectronic properties of extended defects in epitaxial SiC helps elucidate the microstructure of extended defects and can provide pathways to mitigate detrimental changes during device operation related to their evolution, such as the recombination enhanced dislocation glide effect that affects SiC-based MOSFETs.
Sample size dependence of tagged molecule dynamics in steady-state networks with bimolecular reactions: Cycle times of a light-driven pump
Authors: Asnicar Daniele , Penocchio Emanuele , Frezzato Diego
Published: May 2022

Here, steady-state reaction networks are inspected from the viewpoint of individual tagged molecules jumping among their chemical states upon the occurrence of reactive events. Such an agent-based viewpoint is useful for selectively characterizing the behavior of functional molecules, especially in the presence of bimolecular processes. We present the tools for simulating the jump dynamics both in the macroscopic limit and in the small-volume sample where the numbers of reactive molecules are of the order of few units with an inherently stochastic kinetics. The focus is on how an ideal spatial “compartmentalization” may affect the dynamical features of the tagged molecule. Our general approach is applied to a synthetic light-driven supramolecular pump composed of ring-like and axle-like molecules that dynamically assemble and disassemble, originating an average ring-through-axle directed motion under constant irradiation. In such an example, the dynamical feature of interest is the completion time of direct/inverse cycles of tagged rings and axles. We find a surprisingly strong robustness of the average cycle times with respect to the system’s size. This is explained in the presence of rate-determining unimolecular processes, which may, therefore, play a crucial role in stabilizing the behavior of small chemical systems against strong fluctuations in the number of molecules.
Droplet formation simulation using mixed finite elements
Authors: Nathawani Darsh K. , Knepley Matthew G.
Published: May 2022

Droplet formation happens in finite time due to the surface tension force. The linear stability analysis is useful to estimate the size of a droplet but fails to approximate the shape of the droplet. This is due to a highly nonlinear flow description near the point where the first pinch-off happens. A one-dimensional axisymmetric mathematical model was first developed by Eggers and Dupont [“Drop formation in a one-dimensional approximation of the Navier–Stokes equation,” J. Fluid Mech. 262, 205–221 (1994)] using asymptotic analysis. This asymptotic approach to the Navier–Stokes equations leads to a universal scaling explaining the self-similar nature of the solution. Numerical models for the one-dimensional model were developed using the finite difference [Eggers and Dupont, “Drop formation in a one-dimensional approximation of the Navier–Stokes equation,” J. Fluid Mech. 262, 205–221 (1994)] and finite element method [Ambravaneswaran et al., “Drop formation from a capillary tube: Comparison of one-dimensional and two-dimensional analyses and occurrence of satellite drops,” Phys. Fluids 14, 2606–2621 (2002)]. The focus of this study is to provide a robust computational model for one-dimensional axisymmetric droplet formation using the Portable, Extensible Toolkit for Scientific Computation. The code is verified using the Method of Manufactured Solutions and validated using previous experimental studies done by Zhang and Basaran [“An experimental study of dynamics of drop formation,” Phys. Fluids 7, 1184–1203 (1995)]. The present model is used for simulating pendant drops of water, glycerol, and paraffin wax, with an aspiration of extending the application to simulate more complex pinch-off phenomena.
Wake characteristics of complex-shaped snow particles: Comparison of numerical simulations with fixed snowflakes to time-resolved particle tracking velocimetry experiments with free-falling analogs
Authors: Tagliavini Giorgia , Khan Majid H. , McCorquodale Mark , Westbrook Chris , Holzner Markus
Published: May 2022

Experimental and numerical approaches have their own advantages and limitations, in particular, when dealing with complex phenomena such as snow particles falling at moderate Reynolds numbers (Re). Time-resolved, three-dimensional particle tracking velocimetry (4D-PTV) experiments of free-falling, three-dimensional (3D)-printed snowflakes' analogs shed light on the elaborate falling dynamics of irregular snow particles but present a lower resolution (tracer seeding density) and a limited field of view (domain size) to fully capture the wake flow. Delayed-detached eddy simulations of fixed snow particles do not realistically represent all the physics of a falling ice particle, especially for cases with unsteady falling attitudes, but accurately predict the drag coefficient and capture the wake characteristics for steadily falling snowflakes. In this work, we compare both approaches on time- and space-averaged flow quantities in the snowflake wake. First, we cross validate the two approaches for low Re cases, where close agreement of the wake features is expected, and second, we assess how strongly the unsteady falling motion perturbs the average wake pattern as compared to a fixed particle at higher Re. For steadily falling snowflakes, the fixed-particle model can properly represent the wake flow with errors within the experimental uncertainty (±15%). At moderate/high Re (unsteady falling motion), larger differences are present. Applying a co-moving frame to the experimental data to account for the particle movement or filtering the numerical data on larger grids reduces these differences only to some extent, implying that an unsteady fall significantly alters the average wake structure as compared to a fixed particle model.