bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparative transcriptomic analysis of the tea plant (Camellia sinensis) reveals key genes involved in pistil deletion
Authors: Liu Yufei , Pang Dandan , Tian Yiping , Li Youyong , Jiang Huibing , Sun Yunnan , Xia Lifei , Chen Linbo
Published: September 2020

Background

The growth process of the tea plant (Camellia sinensis) includes vegetative growth and reproductive growth. The reproductive growth period is relatively long (approximately 1.5 years), during which a large number of nutrients are consumed, resulting in reduced tea yield and quality, accelerated aging, and shortened economic life of the tea plant. The formation of unisexual and sterile flowers can weaken the reproductive growth process of the tea plant. To further clarify the molecular mechanisms of pistil deletion in the tea plant, we investigated the transcriptome profiles in the pistil-deficient tea plant (CRQS), wild tea plant (WT), and cultivated tea plant (CT) by using RNA-Seq.

Results

A total of 3683 differentially expressed genes were observed between CRQS and WT flower buds, with 2064 upregulated and 1619 downregulated in the CRQS flower buds. These genes were mainly involved in the regulation of molecular function and biological processes. Ethylene synthesis–related ACC synthase genes were significantly upregulated and ACC oxidase genes were significantly downregulated. Further analysis revealed that one of the WIP transcription factors involved in ethylene synthesis was significantly upregulated. Moreover, AP1 and STK, genes related to flower development, were significantly upregulated and downregulated, respectively.

Conclusions

The transcriptome analysis indicated that the formation of flower buds with pistil deletion is a complex biological process. Our study identified ethylene synthesis, transcription factor WIP, and A and D-class genes, which warrant further investigation to understand the cause of pistil deletion in flower bud formation.
Ishige okamurae reduces blood glucose levels in high-fat diet mice and improves glucose metabolism in the skeletal muscle and pancreas
Authors: Yang Hye-Won , Son Myeongjoo , Choi Junwon , Oh Seyeon , Jeon You-Jin , Byun Kyunghee , Ryu Bo Mi
Published: September 2020

Brown alga (Ishige okamurae; IO) dietary supplements have been reported to possess anti-diabetic properties. However, the effects of IO supplements have not been evaluated on glucose metabolism in the pancreas and skeletal muscle. C57BL/6 N male mice (age, 7 weeks) were arranged in five groups: a chow diet with 0.9% saline (NFD/saline group), high-fat diet (HFD) with 0.9% saline (HFD/saline group). high-fat diet with 25 mg/kg IO extract (HFD/25/IOE). high-fat diet with 50 mg/kg IO extract (HFD/50/IOE), and high-fat diet with 75 mg/kg IO extract (HFD/75/IOE). After 4 weeks, the plasma, pancreas, and skeletal muscle samples were collected for biochemical analyses. IOE significantly ameliorated glucose tolerance impairment and fasting and 2 h blood glucose level in HFD mice. IOE also stimulated the protein expressions of the glucose transporters (GLUTs) including GLUT2 and GLUT4 and those of their related transcription factors in the pancreases and skeletal muscles of HFD mice, enhanced glucose metabolism, and regulated blood glucose level. Our results suggest Ishige okamurae extract may reduce blood glucose levels by improving glucose metabolism in the pancreas and skeletal muscle in HFD-induced diabetes.
Elucidation of predictors of disease progression in patients with relapsing polychondritis at the onset: potential impact on patient monitoring
Authors: Shimizu Jun , Yamano Yoshihisa , Kawahata Kimito , Suzuki Noboru
Published: September 2020

Background

In patients with relapsing polychondritis (RP), organ involvement developed in those with progressive and/or long disease courses. For their management, elucidation of a subgroup suggesting disease progression is awaited.

Methods

We previously conducted a physician’s questionnaire-based retrospective study to elucidate major clinical features of Japanese patients with RP. We here evaluated organ involvement at disease onset and at the last follow-up. We then counted cumulative numbers of involved organs at the last follow-up in 229 RP patients and compared them with involved organ numbers at disease onset, as possible indicators of disease progression. We assigned their prognosis at the last follow-up into “patient prognostic stages” from no medication (stage 1) to death (stage 5). We utilized nonparametric tests for group comparisons.

Results

Involved organ numbers per-patient were 1.13 ± 0.03 at disease onset and 3.25 ± 0.10 at the last follow-up (disease duration was 4.69 ± 0.33 years), and increased along with the patient prognostic stages.

At disease onset, 135 and 48 patients had auricular involvement (59% of 229 patients, defined as auricular-onset subgroup; AO) and respiratory involvement (21%, respiratory-onset subgroup; RO), respectively. 46 patients presented with other conditions (20%, miscellaneous-onset subgroup; MO) including CNS, ocular, and inner ear involvement, among others.

RO patients showed worse (poorer) prognostic stages than AO patients. MO patients developed respiratory and/or auricular involvement thereafter and then showed significantly higher mortality rate (15%; 7/46) than AO patients (5.9%; 8/135).

In RP patients who did not develop respiratory involvement until the last follow-up (throughout the disease course; 117 patients), mortality rate was 19% in 26 MO patients and 3.3% in 91 AO patients. Accordingly, RO patients and MO patients associated with relatively poor prognosis compared with AO patients.

Conclusions

Allocation of patients to RO and MO subgroups was suggested to associate with poorer prognosis of RP than AO subgroups, especially AO subgroups without respiratory involvement throughout. All RP patients deserve careful monitoring but special attention should be paid to MO patients because of their diverse and accelerated disease progression.
Endovascular management of an unsual case of spontaneous Retroperitoneal Haemorrhage due to Fibromuscular Dysplasia
Authors: Molina-Nuevo Juan David , López-Martínez Lorena , Pedrosa-Jiménez María José , Juliá-Molla Enrique
Published: September 2020

Background

Fibromuscular dysplasia (FMD) is an uncommon vascular disease that results in stenosis, dissection or aneurysmal degeneration. However, it can sometimes manifest atypically, as we show in this case.

Case presentation

A 24-year old patient with no relevant medical history with severe left hypochondrium pain. The physical examination showed blood pressure levels of 160/90 mmHg. An abdominopelvic CT evidenced left retroperitoneal haematoma associated with active bleeding and left renal artery stenosis. Given these findings, it was decided to perform an endovascular treatment. Significant stenosis was seen during the arteriography in both renal arteries, suggesting fibromuscular dysplasia and development of a collateral neovascular network responsible for the retroperitoneal haematoma. It was embolised in association with angioplasty of the left renal artery. The patient had a favourable outcome; however, high blood pressure levels persisted. A new bilateral renal angioplasty was performed, which returned blood pressure values to normal. The patient was discharged without needing antihypertensives.

Conclusions

FMD is a rare disease that can show multiple clinical presentations and need individualized treatment options. Endovascular techniques are in the first therapeutic line regarding fibromuscular dysplasia.
Antiplasmodial activities and abortifacient properties of three commonly used African indigenous anti-malarial plants in Plasmodium berghei infected pregnant mice: implication for maternal and fetal health
Authors: Babalola Ayodele S. , Idowu Olufunmilayo A. , Ademolu Kehinde O. , Olukunle J. , Rahman Samson A.
Published: September 2020

Background

The use of herbs for malaria treatment is common among pregnant women in Nigeria. This study through a survey documented three most commonly used herbs in the management of pregnancy-associated malaria in Abeokuta, Nigeria. This study also evaluated the efficacy and abortifacient properties of the selected herbs against established Plasmodium berghei NK65 infection in 110 experimental pregnant mice randomly distributed into 22 groups and treated with extracts of Morinda lucida (L.) Benth. (Rubiaceae), Enantia chlorantha (oliv.) (Annonaceae), and Cymbopogon citatrus (Stapf) (Poaceae) at a graded dose of 100, 200, and 300 mg/kg and Sulphadoxine-pyrimethamine (Fansidar) at 10 mg/kg.

Results

From the survey, Cymbopogon citratus (Leaf), Morinda lucida (Leaf), and Enanthia chlorantha (Bark) were the most frequently mentioned to be useful in management of malaria during pregnancy. Both M. lucida and E. chlorantha produced up to 70% P. gerghei chemosuppression in a dose dependent manner. Chemosupression was less than 50% in mice treated with C. citratus extracts. E. chlorantha induced abortion, while extracts of C. citratus and M. lucida caused miscarriage in pregnant mice. Progesterone titters were reduced in mice treated with plant extracts compared with those administered with Fansidar and untreated groups (p < 0.05).

Conclusion

This study showed that M. lucida and E. chlorantha had anti-malarial properties, which are promising in reducing problems with pregnancy associated malaria in the face of growing resistance to currently available drugs. However, they are capable of inducing abortion by impairing the production of progesterone. In order to reduce the risk of danger posed by use of herbs in pregnancy on mothers and the developing fetus, there is need for proper awareness on the possible abortifacient and teratogenic properties of herbs used in management of malaria during pregnancy.
Variety of radiological findings in a family with COVID-19: a case report
Authors: Gharekhanloo Farideh , Sedighi Iraj , Khazaei Salman
Published: September 2020

Introduction

In December 2019, a case series of pneumonia associated with seafood and wet animal market was reported as coronavirus disease 2019 (COVID-19) in Wuhan, Hubei, China. The COVID-19 less frequently affects the pediatric group, and asymptomatic children are commonly reported. This feature is important due to the potential transmissibility of COVID-19 through these cases. There is a variety of atypical clinical symptoms and imaging manifestations among children infected with COVID-19.

Case presentation

We report two sisters with COVID-19 pneumonia who had close contact with their 77-year-old grandmother. Their grandmother expired with a confirmed diagnosis of COVID-19. The older sister (15 years old) firstly presented with severe cough, fever, dyspnea, diarrhea, and lymphopenia. A chest computed tomography (CT) scan showed atypical lobar pneumonic infiltration only in the left lower lobe. The younger sister (6 years old) was affected the following day with milder symptoms (i.e., fever and cough). Her chest CT scan demonstrated typical mild generalized patchy ground-glass opacity with interlobular septal thickening scattered in both lungs. The CT presentation of their grandmother showed typical bilateral white lungs with crazy paving appearance. The standard regimen for both sisters was administrated, and the patients’ respiratory conditions improved after 5 days of treatment. Both cases were discharged with good general conditions.

Conclusion

Children are considered potentially important causes of COVID-19 transmission. The symptoms in children are milder, and clinicians should be aware of taking a definite history of infected family members. Atypical clinical symptoms and imaging features are more common in children than adults; therefore, it is necessary to identify the typical and atypical imaging patterns of COVID-19 pneumonia in the pediatric population.
Multidisciplinary Management of Cancer During Pregnancy
Authors: Silverstein Jordyn , Post Annalisa L. , Chien A. Jo , Olin Rebecca , Tsai Katy K. , Ngo Zoe , Van Loon Katherine
Published: September 2020

Cancer during pregnancy is relatively rare but is increasing in frequency in countries in which the maternal child-bearing age continues to rise. The complexities of medical decision making are underscored by the need to weigh the potential benefits of any intervention for the mother against the risks to the fetus. A majority of diagnostic evaluations can be performed safely in the setting of pregnancy and should not be delayed. Noninvasive prenatal testing that shows discordance with fetal karyotype can be a clue to an underlying maternal malignancy. After diagnosis, a multidisciplinary team should formulate a care plan for both the mother and the fetus. Key topics for discussion should include the mother’s prognosis, standard treatment plan, and predictions of how modifications for a continuing pregnancy will affect the treatment plan and overall prognosis. In the context of this knowledge, frank discussions about pregnancy termination should be addressed with the patient, if appropriate. Selection of a plan for oncologic management in the case of a pregnant woman is based on the type of cancer, the tumor biology, and the tumor stage. Additional complexities for pregnant patients are typically related to the gestational age of the fetus, the dynamic physiologic changes of pregnancy, and the limited safety data for administration of most anticancer therapies during pregnancy. In this article, we summarize data related to different classes of anticancer therapies as well as considerations for the management of selected cancers. Finally, we provide some key principles that should be considered in the management of patients with cancer during pregnancy.
Evaluation of the Implementation of FDG-PET/CT and Staging Laparoscopy for Gastric Cancer in The Netherlands
Authors: Gertsen Emma C. , Borggreve Alicia S. , Brenkman Hylke J. F. , Verhoeven Rob H. A. , Vegt Erik , van Hillegersberg Richard , Siersema Peter D. , Ruurda Jelle P. ,   on behalf of the Dutch Upper Gastrointestinal Cancer Audit (DUCA) Group
Published: September 2020

Background

The role of 18F-fluorodeoxyglucose positron emission tomography with computed tomography (FDG-PET/CT) and staging laparoscopy (SL) has increased in the preoperative staging of gastric cancer. Dutch national guidelines have recommended the use of FDG-PET/CT and SL for patients with locally advanced tumors since July 2016.

Objective

The aim of this study was to evaluate the implementation of FDG-PET/CT and SL in The Netherlands.

Methods

Between 2011 and 2018, all patients who underwent surgery for gastric cancer were included from the Dutch Upper GI Cancer Audit. The use of FDG-PET/CT and SL was evaluated before and after revision of the Dutch guidelines. Outcomes included the number of non-curative procedures (e.g. palliative and futile procedures) and the association of FDG-PET/CT and SL, with waiting times from diagnosis to the start of treatment.

Results

A total of 3310 patients were analyzed. After July 2016, the use of FDG-PET/CT (23% vs. 61%; p < 0.001) and SL (21% vs. 58%; p < 0.001) increased. FDG-PET/CT was associated with additional waiting time to neoadjuvant therapy (4 days), as well as primary surgical treatment (20 days), and SL was associated with 8 additional days of waiting time to neoadjuvant therapy. Performing SL or both modalities consecutively in patients in whom it was indicated was not associated with the number of non-curative procedures.

Conclusion

During implementation of FDG-PET/CT and SL after revision of the guidelines, both have increasingly been used in The Netherlands. The addition of these staging methods was associated with increased waiting time to treatment. The number of non-curative procedures did not differ after performing none, solely one, or both staging modalities.
Investigating and evaluating evidence of the behavioural determinants of adherence to social distancing measures – A protocol for a scoping review of COVID-19 research
Authors: Noone Chris , Warner Nikolett , Byrne Molly , Durand Hannah , Lavoie Kim L. , McGuire Brian E. , McSharry Jenny , Meade Oonagh , Morrissey Eimear , Molloy Gerry , O'Connor Laura , Toomey Elaine
Published: September 2020

Background: The WHO has declared the outbreak of coronavirus disease 2019 (COVID-19) as a pandemic. With no vaccine currently available, using behavioural measures to reduce the spread of the virus within the population is an important tool in mitigating the effects of this pandemic. As such, social distancing measures are being implemented globally and have proven an effective tool in slowing the large-scale spread of the virus.

Aim: This scoping review will focus on answering key questions about the state of the evidence on the behavioural determinants of adherence to social distancing measures in research on COVID-19. 

Methods: A scoping review will be conducted in accordance with guidelines for best practice. Literature searches will be conducted using online databases and grey literature sources. Databases will include Medline, Web of Science, Embase and PsycInfo, alongside relevant pre-print servers. Grey literature will be searched on Google Scholar. Screening, data extraction and quality appraisal will be conducted by members of the research team, with any discrepancies resolved by consensus discussion. Quality appraisal will be conducted using the Cochrane’s ROBINS-I tool, the Cochrane Risk of Bias tool, and the JBI Critical Appraisal Checklist where appropriate. Results will be analysed by mapping findings onto the Theoretical Domains Framework and visualising characteristics of the included studies using EviAtlas. This scoping review is pre-registered with Open Science Framework.

Conclusions The results of this study may facilitate the systematic development of behavioural interventions to increase adherence to social distancing measures.
The history of femoroacetabular impingement
Authors: Matsumoto Kenki , Ganz Reinhold , Khanduja Vikas
Published: September 2020

Aims

Femoroacetabular impingement (FAI) describes abnormal bony contact of the proximal femur against the acetabulum. The term was first coined in 1999; however what is often overlooked is that descriptions of the morphology have existed in the literature for centuries. The aim of this paper is to delineate its origins and provide further clarity on FAI to shape future research.

Methods

A non-systematic search on PubMed was performed using keywords such as “impingement” or “tilt deformity” to find early anatomical descriptions of FAI. Relevant references from these primary studies were then followed up.

Results

Although FAI has existed for almost 5,000 years, the anatomical study by Henle in 1855 was the first to describe it in the literature. The relevance of the deformity was not appreciated at the time but this triggered the development of further anatomical studies. Parallel to this, Poland performed the first surgical correction of FAI in 1898 and subsequently, descriptions of similar procedures followed. In 1965, Murray outlined radiological evidence of idiopathic cam-type deformities and highlighted its significance. This led to a renewed focus on FAI and eventually, Ganz et al released their seminal paper that has become the foundation of our current understanding of FAI. Since then, there has been an exponential rise in published literature but finding a consensus, especially in the diagnosis of FAI, has proven to be difficult.

Conclusion

Current research on FAI heavily focuses on new data, but old evidence does exist and studying it could be equally as important in clarifying the aetiology and classification of FAI. Cite this article: Bone Joint Res 2020;9(9):572–577.
UV-vis spectroscopic studies of low-energy argon-ion-bombarded ion-exchanged glasses
Authors: Zhang Wenjie , Zhao Zhimin , Xie Zijuan , Liu Zhenlu , Yu Xiaoyan
Published: September 2020

The ion-exchanged glasses bombarded with 80 eV, 100 eV, and 120 eV argon ions at room temperature are investigated. The optical and structural properties of ion-exchanged glasses before and after bombardment were analyzed by means of a UV-vis spectrometer, x-ray photoelectron spectroscopy, and electron probe micro analysis, respectively. The optical absorption and transmittance spectra of ion-exchanged glasses appear as obvious changes in the UV-visible region after bombardment. The optical absorption band and transmittance properties of ion-exchanged glasses at about 369–900 nm are less sensitive to the ion bombardment energy than that at about 200–280 nm. The changes in binding energy shift and peak area ratios of non-bridging oxygen and bridging oxygen contributions to the O 1s lines were observed with increasing ion beam bombardment energy. Accompanied with out-diffusion of potassium cations during argon ion bombardment, the peak of potassium cations concentration in the exchanged region decreases and moves into the interior of glasses in different degrees. The results show that variation of structure and optical properties of the ion-exchanged glasses are indicative of alterations of the silicate network structure induced by argon ion bombardment, which provide important information for application of the ion-exchanged glasses.
Numerical investigation of an ultra-broadband, wide-angle, and polarization-independent metasurface light absorber
Authors: Zhang Ke , Deng Ruixiang , Song Lixin , Zhang Tao
Published: September 2020

In this paper, we propose and numerically investigate an ultra-broadband, wide-angle, and polarization-independent metasurface absorber based on periodic hexagon-latticed titanium (Ti) nanoring arrays over a continuous Ti film. The proposed absorber can achieve more than 90% absorptivity under normal incidence, ranging from 350 to 1453 nm, and the average absorption is up to 95.6%. Additionally, the absorptivity still remained beyond 70% when the incident angles varied from 0° to 60°. The simulations of electric field distributions indicate that the broadband absorption performance can be ascribed to the superposition of the localized surface plasmon resonance (LSPR) originated from the nanopillars and nanoholes, respectively. The proposed approach is simple and inexpensive, and the metal material is optional. Therefore, we believe that the proposed absorber will be a candidate for many potential applications, such as thermophotovoltaic cells, thermal emitters, and optoelectronic devices.
Optical single-sideband polarization modulator based on Sagnac interferometers and its applications in radio-over-fiber systems
Authors: Ganjali Mohsen , Safavi Najmeh , Qashqaei Mohammadreza , Hosseini S. Esmail
Published: September 2020

A novel scheme to implement an optical single-sideband (OSSB) polarization modulator (PolM) is proposed and theoretically demonstrated in this paper. The proposed OSSB-PolM is based on the phase modulation technique in two consecutive Sagnac interferometers (SIs). It is shown that by applying four equal-power radio frequency (RF) signals with appropriate phases to electro-optic modulators and aligning the polarization state of the modulated signal in the proper direction, an OSSB-PolM signal will be generated. The proposed scheme can find many microwave photonic (MWP) applications. To show this, an OSSB modulator with tunable optical carrier-to-sideband ratio, an OSSB-suppressed carrier modulator/optical frequency shifter, and a full-ranged MWP phase shifter are proposed and demonstrated. The proposed structure includes several important advantages. For instance, the system is free from the limitations caused by optical/electrical filters. Since the propagating lights in an SI traverse the identical optical path in clockwise and counterclockwise directions, the system is immune to environmental perturbations. Furthermore, there is no need for a bias control circuit, so the system has a stable operation. In addition, the proposed scheme can be extended to multichannel applications in array antennas. Theoretically, calculations have been verified by simulation results.
Polarization properties of noise-initiated stimulated Brillouin scattering in linear birefringent fibers
Authors: Bowers Mark S.
Published: September 2020

The transient theory of stimulated Brillouin scattering (SBS) is developed for optical fibers with constant modal birefringence along its length and arbitrary polarization of the pump and Stokes fields. SBS is initiated by thermally excited acoustic waves distributed along the length of the optical fiber, and the generated Stokes field fluctuates in time. It is shown that when a single-frequency pump field is launched such that the fiber is nearly equally excited along the slow and fast axes, the generated Stokes field is partially polarized for fiber lengths longer than its polarization beat length, due to temporal fluctuations in power and polarization. The Stokes field degree of polarization is reduced as the birefringence of the fiber is increased. For launched pump polarizations resulting in nonequal excitation along the slow and fast axes of the fiber, the generated Stokes field is preferentially linearly polarized along the principal axis that exhibits the highest Brillouin gain for fibers with birefringence such that its length is greater than twice its polarization beat length. As the fiber birefringence is reduced, the generated Stokes field state of polarization moves towards the launched pump polarization state, with the opposite sense of rotation. Numerical results are presented to quantify these effects as a function of single-pass Brillouin gain, fiber birefringence, and launched pump polarization state.
Single-snapshot X-ray imaging for nonlinear compressive tomosynthesis
Authors: Zhao Qile , Ma Xu , Cuadros Angela , Mao Tianyi , Arce Gonzalo R.
Published: September 2020

Traditional compressive X-ray tomosynthesis uses sequential illumination to interrogate the object, leading to long scanning time and image distortion due to the object variation. This paper proposes a single-snapshot compressive tomosynthesis imaging approach, where the object is simultaneously illuminated by multiple X-ray emitters equipped with coded apertures. Based on rank, intensity and sparsity prior models, a nonlinear image reconstruction framework is established. The coded aperture patterns are optimized based on uniform sensing criteria. Then, a modified split Bregman algorithm is developed to reconstruct the object from the set of nonlinear compressive measurements. It is shown that the proposed method can be used to reduce the inspection time and achieve robust reconstruction with respect to shape variation or motion of objects.
Using multidimensional speckle dynamics for high-speed, large-scale, parallel photonic computing
Authors: Sunada Satoshi , Kanno Kazutaka , Uchida Atsushi
Published: September 2020

The recent rapid increase in demand for data processing has resulted in the need for novel machine learning concepts and hardware. Physical reservoir computing and an extreme learning machine are novel computing paradigms based on physical systems themselves, where the high dimensionality and nonlinearity play a crucial role in the information processing. Herein, we propose the use of multidimensional speckle dynamics in multimode fibers for information processing, where input information is mapped into the space, frequency, and time domains by an optical phase modulation technique. The speckle-based mapping of the input information is high-dimensional and nonlinear and can be realized at the speed of light; thus, nonlinear time-dependent information processing can successfully be achieved at fast rates when applying a reservoir-computing-like-approach. As a proof-of-concept, we experimentally demonstrate chaotic time-series prediction at input rates of 12.5 Gigasamples per second. Moreover, we show that owing to the passivity of multimode fibers, multiple tasks can be simultaneously processed within a single system, i.e., multitasking. These results offer a novel approach toward realizing parallel, high-speed, and large-scale photonic computing.
Advanced dispersion engineering of a III-nitride micro-resonator for a blue frequency comb
Authors: Eshaghian Dorche Ali , Timuçin Doğan , Thyagarajan Krishnan , Wunderer Thomas , Johnson Noble , Schwartz David
Published: September 2020

A systematic dispersion engineering approach is presented toward designing a III-nitride micro-resonator for a blue frequency comb. The motivation for this endeavor is to fill the need for compact, coherent, multi-wavelength photon sources that can be paired with, e.g., the 171Yb+ ion in a photonic integrated chip for optical sensing, time-keeping, and quantum computing applications. The challenge is to overcome the normal material dispersion exhibited by the otherwise ideal (i.e., low-loss and large-Kerr-coefficient) AlGaN family of materials, as this is a prerequisite for bright-soliton Kerr comb generation. The proposed approach exploits the avoided-crossing phenomenon in coupled waveguides to achieve strong anomalous dispersion in the desired wavelength range. The resulting designs reveal a wide range of dispersion response tunability, which is expected to allow access to the near-UV wavelength regime as well. Numerical simulations of the spatio-temporal evolution of the intra-cavity field under continuous-wave laser pumping confirm that such a structure is capable of generating a broadband blue bright-soliton Kerr frequency comb. The proposed micro-resonator heterostructure is amenable to the current state-of-the-art growth and fabrication methods for AlGaN semiconductors.
Large magnitude, sign controllable, ultrafast group-velocity control via resonant cascaded nonlinearity in tandem
Authors: Zhou Bingjie , Ma Jingui , Wang Jing , Yuan Peng , Xie Guoqiang , Qian Liejia
Published: September 2020

Resonant cascaded nonlinearity (RCN) induced by optical parametric amplification (OPA) in a chirped quasi-phase-matching chip can be applied to control the group velocity of ultrafast lasers. However, the group delay produced in a single-stage OPA is limited to the pulse duration, and its sign cannot be altered. In this study, we propose a tandem RCN configuration with multiple OPA stages that can produce large-magnitude and sign-controllable group delays. The group delay produced in the multi-stage configuration is shown to be a linear superposition of each single-stage group delay. By virtue of the byproduct idler in the OPA process, the signal-group delay can be altered from positive to negative (and vice versa) with the same chip structure and pump condition. In the numerical simulation with two OPA stages, both a positive and negative group delay of six-fold pulse duration were achieved for 100-fs pulses at 1550 nm. A much larger group delay can be achieved by increasing the number of OPA stages.
Highly efficient optical antenna with small beam divergence in silicon waveguides
Authors: Ginel-Moreno Pablo , Pereira-Martín Daniel , Hadij-ElHouati Abdelfettah , Ye Winnie N. , Melati Daniele , Xu Dan-Xia , Janz Siegfried , Ortega-Moñux Alejandro , Wangüemert-Pérez J. Gonzalo , Halir Robert , Molina-Fernández Íñigo , Schmid Jens H. , Cheben Pavel
Published: September 2020

Optical antennas are key components in optical phased arrays for light detection and ranging technology requiring long sensing range and high scanning resolution. To achieve a narrow beam width in the far-field region, antenna lengths of several millimeters or more are required. To date, such long antennas have been impossible to achieve in silicon waveguides because currently demonstrated technologies do not allow accurate control of grating strength. Here, we report on a new type of surface-emitting silicon waveguide with a dramatically increased antenna length of

L
=

3.65

m
m

. This is achieved by using a subwavelength metamaterial waveguide core evanescently coupled with radiative segments laterally separated from the core. This results in a far-field diffracted beam width of 0.025°, which is a record small beam divergence for a silicon photonics surface-emitting device. We also demonstrate that by using a design with

L

-shaped surface-emitting segments, the radiation efficiency of the antenna can be substantially increased compared to a conventional design, with an efficiency of 72% at the wavelength of 1550 nm.
Multi-source aliasing suppression for distributed fiber acoustic sensing with directionally coherent enhancement technology
Authors: Wang Zhaoyong , Yang Junqi , Gu Jinfeng , Lu Bin , Ye Lei , Ying Kang , Ye Qing , Qu Ronghui , Cai Haiwen
Published: September 2020

Distributed fiber acoustic sensing (DAS) can detect almost all disturbances along the sensing fiber and is widely applied. However, the signals from multiple adjacent disturbance sources are superimposed, according to the sensing principle. A directionally coherent enhancement technology is demonstrated for DAS to suppress multi-source aliasing in air. In preliminary works, two situations are considered for feasibility verification. The submerged weak target signal is effectively extracted from strong broadband noise, and two different same-frequency signals from two sources are separately rebuilt with the same detected signal. As far as we know, this is the first time that the directionally coherent enhancement is proposed for DAS and the multi-source aliasing is suppressed. This technique will help DAS find new important foreground in acoustic detection of large-scale plants with many similar noisy devices, including discharge detection in high voltage substations and acoustic emission flaw detection in mechanical factories.
Versican: A Dynamic Regulator of the Extracellular Matrix
Authors: Islam Shamima , Watanabe Hideto
Published: September 2020

Versican is a large chondroitin sulfate/dermatan sulfate proteoglycan belonging to the aggrecan/lectican family. In adults, this proteoglycan serves as a structural macromolecule of the extracellular matrix in the brain and large blood vessels. In contrast, versican is transiently expressed at high levels during development and under pathological conditions when the extracellular matrix dramatically changes, including in the inflammation and repair process. There are many reports showing the upregulation of versican in cancer, which correlates with cancer aggressiveness. Versican has four classical splice variants, and all the variants contain G1 and G3 domains at N- and C-termini, respectively. There are two glycosaminoglycan attachment domains CSα and CSβ. The largest V0 variant contains both CSα and CSβ, V1 contains CSβ, V2 contains CSα, and the shortest G3 variant has neither of them. Versican degradation is initiated by cleavage at a site in the CSβ domain by ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) proteinases. The N-terminal fragment containing the G1 domain has been reported to exert various biological functions, although its mechanisms of action have not yet been elucidated. In this review, we describe the role of versican in inflammation and cancer and also address the biological function of versikine.
Temperature-Resistant, Corrosion-Tolerant Carburizing Bearing Steel for Aero-Engine Applications
Authors: Kerrigan Aidan , Mondelin Alexandre , Coudert Jean-Baptiste , Sherif Mohamed Y. , Mahéo Yves
Published: September 2020

The development of very high bypass ratio (VHBR) aero-engines can contribute to fulfilling the goals of the Sustainable and Green Engines (SAGE) program. The potential environmental benefits of the new aero-engine concept require increased speed and loading capabilities as compared to today's solutions. This paper describes the development of an advanced temperature-resistant, corrosion-tolerant steel for hybrid bearing rings for aero-engine applications. The target was for an increase in the hybrid bearing load capacity by 15% plus an increase of 25% in the rotation speed capability. In order to achieve the load capacity target, the steel rings of the hybrid bearing needed to be improved in terms of hardness, specifically hot hardness. The composition of Pyrowear® 675 was taken as a basis for the development and the alloying philosophy centered around the use of cobalt because of its beneficial effects on hot hardness. A series of small-scale test melts were made with the initial compositions being modeled using Thermo-Calc software. The heat treatment response of the initial melts was used to define further test melts to refine the composition to a final target composition for an industrial 16-ton Vacuum Induction Melting–Vacuum Arc Remelting (VIM/VAR) melt. This patented novel composition was produced by a commercial steelmaker in the first half of 2018. The paper will describe how the final alloy composition was developed by combining modeling with experimentation. The next steps toward implementation of the concept will be outlined.
Effect of MnS on the Micropitting Behavior of Through Hardened Bearing Steel during Rolling Contact Fatigue
Authors: Bedekar Vikram , Hager Carl , Hyde R. Scott
Published: September 2020

In the manufacturing of bearing steel, sulfur (S) and phosphorous (P) are considered impurities because of their adverse effect on ductility and impact strength. The ASTM standard for through hardened 52100 steel limits its P and S content to 0.025 wt.%. Sulfur reacts with manganese in steel, resulting in manganese sulfide (MnS) inclusions, which are known to enhance machinability. This work contains a summary of an investigation into the influence of MnS inclusions on micropitting. Micropitting damage was produced on rolling contact fatigue test samples operated with a nondimensional film thickness (λ) lower than one. Tests were conducted on through hardened steel samples with two different sulfur contents (approximately 0.002 wt.% and 0.012 wt.% S) under 2.1 GPa maximum Hertzian contact pressure. The percentage of damaged area was measured using image analysis at intervals of one million revolutions up to a total of five million revolutions. The results indicated that the presence of MnS inclusions increases the propensity of steel to sustain micropitting damage. Detailed scanning electron microscopy/focused ion beam (SEM/FIB) and three-dimensional analyses of the MnS inclusions and micropitting damage are included.
Ultrasonic Evaluation of Tailored Forming Components
Authors: Pape Florian , Coors Timm , Matthias Tim , Behrens Bernd-Arno , Poll Gerhard
Published: September 2020

A future trend for machine components such as rolling element bearings is the application of multimaterials for manufacturing. In order to manufacture such components with appropriate quality, a new process chain called Tailored Forming was set up. Within this process chain, joined semifinished workpieces are utilized and formed, followed by a finishing process including heat treatment. Thus, a high-strength steel is joined with a metallic base material such as mild steel or aluminum. In case of a Tailored Forming process, various process steps for joining different materials and a subsequent forming are investigated. This requires high production quality as the production steps build on one another and, in particular, the joining process can significantly influence the component's properties. This is dependent on pores, blowholes, or delamination of the different materials as well as the intermetallic phases existing between steel and aluminum during the joining process. Since the semifinished workpieces go through further process steps, their testing must be nondestructive. Such a test methodology can be realized by scanning acoustic microscopy. The method allows for a tomographic representation of material defects in multimaterial components to enhance the production processes. Typically, ultrasound image examinations are being used in the medical technology. The transfer of this technique to applications with inorganic and, in particular, metallic samples is still associated with great challenges. Metallic components exhibit high velocities and small differences of the ultrasonic signal, which represents a challenge for the digital scanning of ultrasonic measurements for these components. The measurements were performed using a PVA-TePla system with water as the coupling medium. In the case of Tailored Formed bearings, it is possible to evaluate the joining zone regarding defects and pores. This article presents the findings of such evaluations for bearing washers manufactured by plasma welding with a subsequent forming process and impact extruded shafts.
Selective Laser Melting (SLM) of M50NiL—Enabling Increased Degrees of Freedom in New Design Concepts
Authors: Mirring Patrick , Rottmann Andreas , Merklein Carsten
Published: September 2020

Additive manufacturing methods are becoming more and more important due to improvements in the technologies used for “printing,” although additive manufacturing remains a very expensive technology. As such, additive manufacturing is predominantly used in aerospace or medical applications for complex parts that cannot be manufactured with conventional methods. M50NiL, a carburizing heat-resistant steel, is typically used for main shaft bearings in aerospace gas turbine engines. A selective laser melting process for M50NiL was developed for such applications. Analysis of microstructure, hardness, and tensile and rolling contact fatigue testing demonstrated equivalence of M50NiL AM components to components of conventional M50NiL. This equivalence enables new degrees of freedom in designs for main engine shaft bearings (e.g., the integration of oil cooling channels in the outer ring). A comparison of theoretical optimized cooling channel designs and those possible via additive manufacturing was performed considering geometry, surface roughness, and location of the cooling channels.
Rolling Contact Fatigue Transformations in Aero Steels: The Effect of Temperature on Microstructural Decay
Authors: Liang Xingzhong , Sykes Finn , Rivera-Díaz-del-Castillo Pedro E. J.
Published: September 2020

Bearing components undergo failure as a result of rolling contact fatigue (RCF), a prevalent issue in a range of applications including aero engines. RCF can be triggered by microstructural changes at the subsurface including the formation of white etching areas (WEAs), dark etching regions (DERs), and white etching bands (WEBs). For room temperature RCF, such microstructural alterations have been modelled with our recently proposed dislocation-assisted carbon migration theory, which is able to describe the occurrence of microstructural transitions reported in the literature over the last 70 years. This approach naturally incorporates temperature and rotational speed to describe microstructural decay and failure. The model is validated with the literature data available for aerospace bearings. It is shown that temperature-accelerated microstructural transitions and failure can be described with the proposed dislocation-assisted carbon migration theory. The shortcomings of this approach are outlined, and the need for new theory and experimental data is discussed.
The Use of SEM-EDS and PDA-OES Techniques to Help the Development of the Production of Bearing Steel
Authors: Col Audrey , Spadaccini Andrea , Acevedo Daniel , Stocky Christophe
Published: September 2020

The requirements for both stress resistance and durability for reliability in service are ever increasing for bearing steel production. Acciaierie Bertoli Safau (ABS) and ABS Centre Métallurgique (ACM) work together to develop the bearing steel production at ABS and improve its quality. In particular, the cleanliness of the steels—from elecric arc furnace to casting and rolling—has shown to be helpful in controlling the distribution of inclusions in the finished bars. This is of importance for the fatigue properties of the components. This paper focuses on the characterization of inclusion composition during the melting, refining, and casting of a bearing steel. Lollipop samples have been taken at several steps during the steel-making process. This study is focused on understanding the impact of the SiCa additions carried out during the melting and refining on morphology and composition of the inclusions. The analysis of these lollipops via pulse discrimination analysis with optical emission spectrometry (PDA-OES), completed by scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) investigation, allows evaluation of the composition and the size of a large number of inclusions in a steel sample. This paper will briefly present the production process carried out at ABS. It will then review the characterization methods and how the sampling was carried out. The results will be presented and analyzed with the help of the literature in order to build a mechanism for the formation and modification of the inclusions. The outputs of both characterization techniques will be compared.
Complexity of Dimensional Stability of Case-Hardened Bearing Components
Authors: Yan Pei , Sherif Mohamed Y.
Published: September 2020

The thermal effect is the most considered parameter affecting the dimensional stability of a bearing component. It is generally associated with the transformations of the metastable phases in the steel upon exposure to the operating temperature over a long period of time in service. In reality, the dimensional change of the bearing components is thermomechanically activated given that the experienced hoop stress caused by interference fit promotes the dimensional change considerably due to stress relaxation. The phenomenon becomes more complex for case-hardened bearings because the thermomechanical responses of the case and core are different, and the dimensional change is a result of the combined contribution from the case and core. Our previous studies did show the decrease of dimensional stability with the increase of retained austenite content in the case, the case depth, and the interference fit applied during the application. It is challenging, however, to obtain consistent data on microstructural changes accounting for dimensional change possibly because of the inhomogeneity of the microstructure. The current approach is to carry out ring-on-shaft thermal exposure tests complimented with state-of-the-art dilatometry work on the case and core microstructures. This work enables us to assess the dimensional stability of the case-hardened bearing components. The results can then be used to suggest an improved test method and give input to future model development and prediction on dimensional stability of case-hardened bearing components.
Lubricant-Induced White Etching Cracks: Mechanism and Effects of Surface Finishing
Authors: Paladugu Mohanchand
Published: September 2020

Cylindrical roller thrust bearings (CRTBs) were fatigue tested in various lubricants under rolling-sliding conditions. The bearings exhibited premature damage when the tests were performed in a lubricant containing significant additives (referred to in this paper as “test gear oil”). Bearing life in the test gear oil was less than 5% of bearing life when tested in a mineral oil containing no additives. Investigations on posttest bearings from the test gear oil revealed localized raised areas on the tribosurfaces of the raceways. Upon further examination, subsurface white etching cracks (WECs) were observed beneath the raised surface features. The raised areas resembled hydrogen-induced blisters. Subsequent thermal desorption spectroscopy analysis of the bearing races with the raised features revealed hydrogen evolution from the posttest raceways. In contrast, races exhibited typical point surface origin (PSO)-type damage when the bearings were tested in plain mineral oil. Also, there were no subsurface crack networks or white etching features associated with the PSO spalling damage. Additional tests were performed with embedded abrasive particles that were introduced onto the raceways using a lapping process. Posttest investigations showed neither the raceways nor the rollers contained WECs, and the damage mode had changed even though they were tested in the test gear oil. Although WECs are generated in the subsurface, their formation depends on the surface condition of the raceways, so these results suggest that WEC formation is a surface-driven phenomenon. Based on these insights, possible WEC mitigation and prevention methods are discussed.