bluuebunny/crossref_metadata_2025 huggingface dataset:
Nanofluids in Solar Thermal Collectors: Review and Limitations
Authors: Wole-osho Ifeoluwa , Okonkwo Eric C. , Abbasoglu Serkan , Kavaz Doga
Published: September 2020

Solar thermal collectors are systems that allow for the use of solar energy in thermal applications. These collectors utilize a heat transfer fluid to transport absorbed solar radiation to applications where they are needed. Scientists in a bid to improve the conversion efficiency of solar collectors have suggested different collector designs and improved collector materials. Over the last 25 years, the study of nanofluids and their applications have revolutionized material science, and nanotechnology has found applications in improving solar collector materials. This article reviews the impact of different nanomaterials on the efficiency of solar collectors. The study also outlines the limitations of applying nanofluids and discusses the long-term challenges of their application to solar collectors. Nanofluids have the potential to improve the overall efficiency of most solar collectors, however, the full potential of nanofluids in heat transfer applications cannot be completely achieved until some of the questions regarding hysteresis, stability, and the overall predictability of nanofluids are answered.
The origin of constant phase element in equivalent circuit of MIS (n) GaAs structures
Authors: Drewniak Łukasz , Kochowski Stanisław
Published: September 2020

The Au/Pd/Ti–SiO2-(n) GaAs properties have been analyzed via impedance spectroscopy (IS), as well as DLTS and ICTS, to identify the origin of electron processes responsible for existence of constant phase elements (CPE) in an equivalent circuits of that structure. We showed that CPEs connected in series with resistance represents the electron processes associated with deep levels in GaAs and/or interface states at SiO2-(n) GaAs interface, depending on the value of n of CPE parameter. CPE with n close to 1 characterize the electron processes associated with EL2 deep level, and CPE with n = 0.5–0.65 the complex electron processes associated with EL3 deep level and interface states together. We stated that constant phase elements in equivalent circuits of MIS-GaAs structures with large frequency dispersion of electrical characteristics can be the result of more than one electron process.
Rank-Engel conditions on linear groups
Authors: Wehrfritz B. A. F.
Published: September 2020

We study linear groups G for which for every g in G there exists a subgroup E of G satisfying some sort of rank condition and such that for every x in G there is a positive integer m such that for all n ≥ m the repeated commutator [x, ng] lies in E. If E can always be chosen to be a Chernikov group (resp. a polycyclic-by-finite group) such G can be completely described (Wehrfritz in Adv Group Theory Appl 7:143–157, 2019; Wehrfritz in Boll Unione Mat Ital, to appear). For more general rank conditions our analyses below are complete for positive characteristics but are less so for characteristic zero.
New Insights into the Failure Front Phenomenon and the Equation of State of Soda-Lime Glass Under Planar Plate Impact
Authors: Bauer S. , Bagusat F. , Strassburger E. , Sauer M. , Hiermaier S.
Published: September 2020

A systematic study has been performed to gather more detailed experimental information on the equation of state and the Hugoniot elastic limit (HEL) of soda-lime glass as well as the failure front phenomenon. The key innovations of this study comprise experimental as well as analytical aspects. On the one hand, an extensive planar plate impact (PPI) test series has been carried out over a wide range of shock loading stress levels instrumented with two high-speed cameras and laser interferometers (PDV and VISAR). On the other hand, a systematic analysis concept has been developed and evaluated, including a combination of Lagrange diagrams with velocity profile data and a derivation of the equation of state together with an error estimation. Impact velocities ranged from 500 to 3000 m/s resulting in loadings of the soda-lime glass targets between 3.5 and 20.8 GPa. For stress levels between 3.5 and 6.7 GPa two high-speed cameras with 5 Mfps, positioned at the side and rear of the specimens, enabled the observation of shock waves and two different kinds of failure fronts. Therefore, visual information could be gathered not only in the purely elastic regime, but also in the transition region above 4 GPa and at stress levels beyond the HEL. The HEL of the soda-lime glass is determined to $$\left(5.0 \pm 0.2\right) \mathrm{GPa}$$

5.0
±
0.2

GPa

. For the onset of an internal failure front a minimum longitudinal stress between 3.8 and 3.9 GPa is identified. The evaluated failure front velocities range from 800 to 2100 m/s. From the observed release response a minimum spall strength of 6.7 GPa and release wave velocities between 5740 and 9500 m/s are deduced.
Long-Term Ivacaftor in People Aged 6 Years and Older with Cystic Fibrosis with Ivacaftor-Responsive Mutations
Authors: Pilewski Joseph M. , De Boeck Kris , Nick Jerry A. , Tian Simon , DeSouza Cynthia , Higgins Mark , Moss Richard B.
Published: September 2020

Introduction

Mutations in the cystic fibrosis transmembrane conductance regulator gene (CFTR) affect the quantity and/or function of CFTR protein reaching the cell surface. Ivacaftor, a CFTR potentiator that enhances chloride transport, increases the channel-open probability of normal and dysfunctional CFTR. Initially approved for people with CF (pwCF) with G551D-CFTR gating mutations, ivacaftor demonstrated clinical benefit in pwCF with other gating mutations and certain residual function mutations, including R117H-CFTR, in clinical studies. We evaluated the long-term safety and efficacy of ivacaftor in pwCF aged 6 years and older with non-G551D-CFTR ivacaftor-responsive mutations.

Methods

Efficacy and safety data from a phase 3, multicenter, open-label, extension study for participants from Study 110 (R117H-CFTR mutations), Study 111 (non–G551D-CFTR gating mutations), and Study 113 (n-of-1 pilot study in participants with residual CFTR function) were analyzed. Following washout from the randomized parent study, participants received oral ivacaftor 150 mg once every 12 h for 104 weeks.

Results

Forty-one of 121 participants completed treatment through 104 weeks; 59 participants who did not complete the extension study continued treatment with commercial ivacaftor. The most common adverse events were pulmonary exacerbation (46.3%) and cough (33.9%). Most treatment-emergent adverse events were mild/moderate in severity and consistent with manifestations of CF or the ivacaftor safety profile. Rapid, durable improvement occurred across all efficacy endpoints.

Conclusions

Ivacaftor was generally safe and well tolerated with no new safety concerns for up to 104 weeks in pwCF with ivacaftor-responsive mutations. The pattern of improvement across efficacy endpoints was durable and generally consistent with parent-study outcomes.

Trial Registration

NCT01707290
Seroprevalence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection among Veterans Affairs healthcare system employees suggests higher risk of infection when exposed to SARS-CoV-2 outside the work environment
Authors: Dimcheff Derek E. , Schildhouse Richard J. , Hausman Mark S. , Vincent Brenda M. , Markovitz Erica , Chensue Stephen W. , Deng Jane , McLeod Melissa , Hagan Danielle , Russell Jon , Bradley Suzanne F.
Published: September 2020

Objective:

The seroprevalence of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) IgG antibody was evaluated among employees of a Veterans Affairs healthcare system to assess potential risk factors for transmission and infection.

Methods:

All employees were invited to participate in a questionnaire and serological survey to detect antibodies to SARS-CoV-2 as part of a facility-wide quality improvement and infection prevention initiative regardless of clinical or nonclinical duties. The initiative was conducted from June 8 to July 8, 2020.

Results:

Of the 2,900 employees, 51% participated in the study, revealing a positive SARS-CoV-2 seroprevalence of 4.9% (72 of 1,476; 95% CI, 3.8%–6.1%). There were no statistically significant differences in the presence of antibody based on gender, age, frontline worker status, job title, performance of aerosol-generating procedures, or exposure to known patients with coronavirus infectious disease 2019 (COVID-19) within the hospital. Employees who reported exposure to a known COVID-19 case outside work had a significantly higher seroprevalence at 14.8% (23 of 155) compared to those who did not 3.7% (48 of 1,296; OR, 4.53; 95% CI, 2.67–7.68; P < .0001). Notably, 29% of seropositive employees reported no history of symptoms for SARS-CoV-2 infection.

Conclusions:

The seroprevalence of SARS-CoV-2 among employees was not significantly different among those who provided direct patient care and those who did not, suggesting that facility-wide infection control measures were effective. Employees who reported direct personal contact with COVID-19–positive persons outside work were more likely to have SARS-CoV-2 antibodies. Employee exposure to SARS-CoV-2 outside work may introduce infection into hospitals.
Dietary intake of branched-chain amino acids and colorectal cancer risk
Authors: Rossi Marta , Mascaretti Federica , Parpinel Maria , Serraino Diego , Crispo Anna , Celentano Egidio , Giacosa Attilio , La Vecchia Carlo
Published: September 2020

An adequate intake of branched-chain amino acids (BCAA) is required for protein synthesis and metabolic functions, including insulin metabolism. Emerging studies found positive associations between BCAA and the risk of various diseases sharing aetiological aspects with colorectal cancer (CRC), including type 2 diabetes, obesity and pancreatic cancer. We investigated the relation between dietary BCAA and CRC using data from a multicentric Italian case–control study, including 1953 cases of CRC (of these, 442 of sigmoid colon) and 4154 hospital controls with acute, non-neoplastic diseases. A validated FFQ was used to estimate the participants’ usual diet and to assess dietary intakes of various nutrients, including energy, BCAA and Ca. OR and corresponding CI were computed by multiple logistic regression models adjusted for age, sex and other confounding factors, including total energy intake. BCAA intake was inversely related to CRC risk (OR for the highest v. the lowest quintile 0·73; 95 % CI 0·55, 0·97), but the association was attenuated after adjustment for Ca intake (OR 0·90; 95 % CI 0·65, 1·25). An inverse association with sigmoid colon cancer risk also remained after adjustment for other dietary factors, including Ca intake (OR 0·49; 95 % CI 0·27, 0·87). This study provides supporting evidence that higher levels of dietary BCAA intake are not associated with an increase of CRC risk, but confirms that they may be related to a reduced risk of sigmoid colon cancer.
Physical Human–Robot Cooperation Based on Robust Motion Intention Estimation
Authors: Alevizos Konstantinos I. , Bechlioulis Charalampos P. , Kyriakopoulos Kostas J.
Published: September 2020

Cooperative transportation by human and robotic coworkers constitutes a challenging research field that could lead to promising technological achievements. Toward this direction, the present work demonstrates that, under a leader–follower architecture, where the human determines the object’s desired trajectory, complex cooperative object manipulation with minimal human effort may be achieved. More specifically, the robot estimates the object’s desired motion via a prescribed performance estimation law that drives the estimation error to an arbitrarily small residual set. Subsequently, the motion intention estimation is utilized in the object dynamics to determine the interaction force between the human and the object. Human effort reduction is then achieved via an impedance control scheme that employs the aforementioned estimations. The feedback relies exclusively on the robot’s force/torque, position as well as velocity measurements at its end effector, without incorporating any other information on the task. Moreover, an adaptive control scheme is adopted to relax the need for exact knowledge of the object dynamics. Finally, an extension for multiple robotic coworkers is studied and verified via simulation, while extensive experimental results for the single robot case clarify the proposed method and corroborate its efficiency.
Brazil in Antarctica: 40 years of science
Authors: Câmara Paulo E.A.S. , Barros-Platiau Ana F. , Andrade Israel De Oliveira , Hillebrand Giovanni R.L.
Published: September 2020

In 2021, Brazilian scientific research in Antarctica will reach its 40 anniversary, and in that period it has experienced good and bad times. How has Brazilian scientific research evolved since its first scientific mission to Antarctica? What were the conditions that enabled this research? How will Brazilian researchers work in the brand-new scientific station? Using an interdisciplinary approach, this article identifies tipping points and the national policy network that led to unstable funding policies. This article highlights four phases of Brazilian Antarctic science and states that there is a clear disconnect between the geopolitical and scientific priorities on one side and the political priorities, including the executive and the legislative powers, on the other.
Energy taxation, subsidy removal and poverty in Mexico
Authors: Labeaga José M. , Labandeira Xavier , López-Otero Xiral
Published: September 2020

Equity and efficiency are crucial issues behind any tax reform, but they are particularly relevant in countries with high inequality and large shares of poverty. This paper provides a comprehensive socio-economic empirical assessment of Mexico's proposed (and partially implemented) tax reforms in the energy domain, and of a hypothetical partial removal of existing electricity subsidies. Using a rich household income and expenditure survey within the context of a demand system adjustment of non-durable goods, the article provides the public-revenue, environmental and distributional impacts from the simulation of different combinations of energy taxation, subsidy-removal and distributive offsets. The paper also provides detailed ex-ante evidence on the effects of compensatory devices that may contribute to the successful implementation of energy reform packages and significant poverty alleviation in Mexico.
Implications of Anomalous Crustal Provinces for Venus' Resurfacing History
Authors: Karlsson R. V. M. K. , Cheng K. W. , Crameri F. , Rolf T. , Uppalapati S. , Werner S. C.
Published: September 2020

Current Venus tectonics suggests a stagnant lid mode of mantle convection. However, the planet is debated to enter an episodic regime after long quiescent periods, driven by resurfacing due to rapid subduction and global crustal recycling. Tessera regions that cover approximately 10% of Venus' surface appear to be strongly deformed, which suggests that they have survived at least the latest resurfacing event, although the composition and age of the tesserae are unknown. Based on mantle convection modeling, we studied the effects of anomalous crustal provinces (ACPs) on mantle dynamics and postoverturn lithospheric survival. As a hypothesis, we assume ACPs to be thick, compositionally anomalous, and rheologically strong units, similar to terrestrial cratons. We model Venus with a varying number of preimposed ACP units and differing lithospheric yield stress in 2‐D and 3‐D spherical geometry. The impact of ACPs on mantle dynamics and the survival of lithosphere is investigated by examining the thermal evolution, crustal thickness, and surface age distribution. We find that the number and timing of overturns are highly dependent on the yield stress and, to some degree, on the number and size of the preimposed ACPs. ACPs in particular affect the wavelength of convection and may foster the survival of lithosphere even of those portions not being part of an ACP. However, ACPs do not seem to be a good analog for tessera regions due to their exaggerated age and (likely) thickness, but—with appropriate density contrast—may be more useful representatives of Venus' highland plateaus.
Using Dirt to Clean Up Construction
Authors: Rocheleau Jackie
Published: September 2020

The construction industry is one of the world’s largest emitters of carbon dioxide. Whether it can reduce those emissions depends on replacing its most common building material.
Wintertime Impacts of the 2019 Super IOD on East Asia
Authors: Doi Takeshi , Behera Swadhin K. , Yamagata Toshio
Published: September 2020

Many parts of East Asia, including Japan, experienced extremely warm conditions during the 2019–2020 winter. These were successfully predicted in October of 2019 by the 108‐member ensemble seasonal prediction system based on the SINTEX‐F climate model. By analyzing covariability of intermember anomalies defined as deviations from the ensemble mean, we have found that the active convection over the western pole of the Indian Ocean Dipole (IOD) caused these unusual conditions over East Asia by generating the meander of the subtropical jet.
Variations of Earthquake Properties Before, During, and After the 2019 M7.1 Ridgecrest, CA, Earthquake
Authors: Cheng Yifang , Ben‐Zion Yehuda
Published: September 2020

We attempt to clarify processes associated with the 2019 Ridgecrest earthquake sequence by analyzing space‐time variations of seismicity, potency values, and focal mechanisms of earthquakes leading to and during the sequence. Over the 20 years before the Mw7.1 mainshock, the percentage of normal faulting events decreased gradually from 25% to below 10%, indicating a long‐term increase of shear stress. The Mw6.4 and Mw7.1 ruptures terminated at areas with strong changes of seismic velocity or intersections with other faults producing arresting barriers. The aftershocks are characterized by highly diverse focal mechanisms and produced volumetric brittle deformation concentrated in a 5–10 km wide zone around the main ruptures. Early aftershocks of the Mw7.1 event extended over a wide area below typical seismogenic depth, consistent with a transient deepening of the brittle‐ductile transition. The Ridgecrest earthquake sequence produced considerable rock damage in the surrounding crust including below the nominal seismogenic zone.
Particle‐in‐Cell Simulation of Rising‐Tone Magnetosonic Waves
Authors: Sun Jicheng , Chen Lunjin , Wang Xueyi , Boardsen Scott , Lin Yu , Xia Zhiyang
Published: September 2020

Recent observations have reported that magnetosonic waves can exhibit rising‐tone structures in the frequency‐time spectrogram. However, the generation mechanism has not been identified yet. In this paper, we investigate the generation of rising‐tone magnetosonic waves in the terrestrial magnetosphere using 1‐D particle‐in‐cell (PIC) simulations, in which the plasma consists of three components: cool electrons, cool protons and ring distribution protons. We find that the magnetosonic waves excited by the ring distribution protons can form a rising‐tone structure with frequency of the structure ranging from about 0.5Ωlh to nearly Ωlh, where Ωlh is the lower hybrid frequency. It is further demonstrated that the rising frequency of magnetosonic waves can be accounted for by the scattering of ring distribution protons. Moreover, the rising‐tone timescale obtained by PIC simulation is compared with the satellite observation. Our findings provide some new insights to understand the nonlinear evolution of plasma waves in the Earth's magnetosphere.
Analysis of Acoustic Observations of Double‐Diffusive Finestructure in the Arctic Ocean
Authors: Shibley Nicole C. , Timmermans Mary‐Louise , Stranne Christian
Published: September 2020

Double‐diffusive convection may occur if both temperature and salinity increase with depth, as in the Arctic Ocean. The process is identifiable by a staircase structure, with mixed layers separated by high‐gradient interfaces in temperature and salinity. These staircases, which persist if turbulence levels are weak, are widely present in the Arctic Ocean and responsible for transporting heat toward the overlying sea ice. Acoustic observations (reflection coefficients) from a broadband echo sounder are analyzed here to track the detailed evolution of interfaces in the Arctic's double‐diffusive staircase. We infer interface thicknesses from reflection coefficient profiles and find that thicknesses appear to be related to water column displacements. Further, we relate reflection coefficients to interface stratification and interpret stratification changes in the context of turbulence acting to thicken interfaces. The high‐resolution capabilities of the echo sounder allow for insights into how double‐diffusive heat fluxes and inferred mixing levels may vary in space/time.
Resonant Whistler‐Electron Interactions: MMS Observations Versus Test‐Particle Simulation
Authors: Behar E. , Sahraoui F. , Berčič L.
Published: September 2020

We present a novel technique to analyze VDF, which allows to capture their fine structure including wave‐particles resonances. By applying the technique to magnetospheric multiscale (MMS) data, the simultaneous observation of characteristic three‐dimensional (3‐D) signatures in the electron velocity distribution function (VDF) and intense quasi‐monochromatic waves in the terrestrial magnetosheath is investigated. The intense wave packets are characterized and modeled analytically as quasi‐parallel circularly polarized whistler waves and applied to a test‐particle simulation in view of gaining insight into the signature of the wave‐particle resonances in velocity space. Both the Landau and the cyclotron resonances were evidenced in the test‐particle simulations. The location and general shape of the test‐particle signatures do account for the observations, but the finer details, such as the symmetry of the observed signatures, are not matched, indicating either the limits of the test‐particle approach or a more fundamental physical mechanism not yet grasped. Finally, it is shown that the energization of the electrons in this precise resonance case cannot be diagnosed using the moments of the distribution function, as done with the classical E · J “dissipation” estimate.
Lower‐Band “Monochromatic” Chorus Riser Subelement/Wave Packet Observations
Authors: Tsurutani Bruce T. , Chen Rui , Gao Xinliang , Lu Quanming , Pickett Jolene S. , Lakhina Gurbax S. , Sen Abhijit , Hajra Rajkumar , Park Sang A , Falkowski Barbara J.
Published: September 2020

Three lower‐band (f < 0.5 fce) chorus riser elements detected in the dayside generation region were studied in detail using the Van Allen Probe data. Two subelements/wave packets within each riser were examined for their wave “frequency” constancy within seven consecutive wave cycles. The seven wave cycles contained the maximum amplitudes of the subelements/packets. Maximum variance B1 zero crossings were used for the identification of wave cycle start and stop times. It is found that the frequency is constant to within ~3% (one standard deviation), with no evidence of upward frequency sweeping over the seven cycles. Continuous wavelet power spectra for the duration of the seven cycles confirm this conclusion. The implication is that a chorus riser element is composed of coherent approximately “monochromatic” steps instead of a gradual sweep in frequency over the whole element. There was no upward frequency stepping where the wave amplitude was the largest, contrary to the sideband theory prediction. It is shown that a chorus riser involves instability of cyclotron resonant energetic electrons from ~6 to ~40 keV at L = 5.8, that is, essentially the whole substorm electron energy spectrum. The above findings may have important consequences for possible wave generation mechanisms. Some new ideas for mechanisms are suggested in conclusion.
Automatic Detection and Location of Seismic Events From Time‐Delay Projection Mapping and Neural Network Classification
Authors: Mosher Stephen G. , Audet P.
Published: September 2020

The past several decades have seen an exponential increase in the volume of available seismic data, and with it has come the need to develop fast, automatic earthquake detection, and location algorithms. Some of the most recent and promising tools come from the field of machine learning. In this study, we combine a recent seismic detection and location method with neural network classification and analyze 4 months of continuous data recorded by a network of 76 stations in northern California. While these approaches have been used separately, our implementation is unique in that it is not constrained by source templates and avoids user‐defined detection thresholds. In particular, we partition our data set into 234,240, 3‐min long time windows with 75% overlap. For each time window, we create a 3D image that captures information about the coherence of the seismic wavefield. We then devise four features as input and train a neural network classifier to predict which time windows in the data set are likely to contain regional seismic events. These features include the second and fourth Hu image moments computed from 2D cross sections of our 3D images and statistical p values that quantify the probability of observing network‐wide power‐spectral density values at 0.2 and 0.5 s. Our neural network model predicts that 2,522 time windows contain seismic events, from which we locate 1,192 unique events.
The Effects of Degassing on Magmatic Gas Waves and Long Period Eruptive Precursors at Silicic Volcanoes
Authors: Jordan Jacob S. , Bercovici David , Liao Yang , Michaut Chloé
Published: September 2020

Cyclical ground deformation, associated seismicity, and elevated degassing are important precursors to explosive eruptions at silicic volcanoes. Regular intervals for elevated activity (6–30 hr) have been observed at volcanoes such as Mount Pinatubo in the Philippines and Soufrière Hills in Montserrat. Here, we explore a hypothesis originally proposed by Michaut et al. (2013, https://doi.org/10.1038/ngeo1928) where porosity waves containing magmatic gas are responsible for the observed periodic behavior. We use two‐phase theory to construct a model where volatile‐rich, bubbly, viscous magma rises and decompresses. We conduct numerical experiments where magma gas waves with various frequencies are imposed at the base of the model volcanic conduit. We numerically verify the results of Michaut et al. (2013, https://doi.org/10.1038/ngeo1928) and then expand on the model by allowing magma viscosity to vary as a function of dissolved water and crystal content. Numerical experiments show that gas exsolution tends to damp the growth of porosity waves during decompression. The instability and resultant growth or decay of gas wave amplitude depends strongly on the gas density gradient and the ratio of the characteristic magma extraction rate to the characteristic magma degassing rate (Damköhler number, Da). We find that slow degassing can lead to a previously unrecognized filtering effect, where low‐frequency gas waves may grow in amplitude. These waves may set the periodicity of the eruptive precursors, such as those observed at Soufrière Hills Volcano. We demonstrate that degassed, crystal‐rich magma is susceptible to the growth of gas waves which may result in the periodic behavior.
Characterization of the intergenerational impact of in utero and postnatal oxycodone exposure
Authors: Odegaard Katherine E. , Schaal Victoria L. , Clark Alexander R. , Koul Sneh , Gowen Austin , Sankarasubramani Jagadesan , Xiao Peng , Guda Chittibabu , Lisco Steven J. , Yelamanchili Sowmya V. , Pendyala Gurudutt
Published: September 2020

Prescription opioid abuse during and after pregnancy is a rising public health concern. While earlier studies have documented that offspring exposed to opioids in utero have impaired neurodevelopment, a significant knowledge gap remains in comparing the overall development between offspring exposed in utero and postnatally. Adding a layer of complexity is the role of heredity in the overall development of these exposed offspring. To fill in these important knowledge gaps, the current study uses a preclinical rat model mimicking oxycodone (oxy) exposure in utero (IUO) and postnatally (PNO) to investigate comparative and intergenerational effects in the two different treatment groups. While significant phenotypic attributes were observed with the two treatments and across the two generations, RNA sequencing revealed alterations in the expression of key synaptic genes in the two exposed groups in both generations. RNA sequencing and post validation of genes using RT-PCR highlighted the differential expression of several neuropeptides associated with the hypocretin system, a system recently implicated in addiction. Further, behavior studies revealed anxiety-like behaviors and social deficits that persisted even in the subsequent generations in the two treatment groups. To summarize, our study for the first time reveals a new line of investigation on the potential risks associated with oxy use during and after pregnancy, specifically the disruption of neurodevelopment and intergenerational impact on behavior.
Stem/progenitor cell-based transplantation for retinal degeneration: a review of clinical trials
Authors: Wang Yiqi , Tang Zhimin , Gu Ping
Published: September 2020

Retinal degeneration (RD) is one of the dominant causes of irreversible vision impairment and blindness worldwide. However, the current effective therapeutics for RD in the ophthalmologic clinic are unclear and controversial. In recent years, extensively investigated stem/progenitor cells—including retinal progenitor cells (RPCs), embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs) and mesenchymal stromal cells (MSCs)—with proliferation and multidirectional differentiation potential have presented opportunities to revolutionise the ultimate clinical management of RD. Herein, we provide a comprehensive overview on the progression of clinical trials for RD treatment using four types of stem/progenitor cell-based transplantation to replace degenerative retinal cells and/or to supplement trophic factors from the aspects of safety, effectiveness and their respective advantages and disadvantages. In addition, we also discuss the emerging role of stem cells in the secretion of multifunctional nanoscale exosomes by which stem cells could be further exploited as a potential RD therapy. This review will facilitate the understanding of scientists and clinicians of the enormous promise of stem/progenitor cell-based transplantation for RD treatment, and provide incentive for superior employment of such strategies that may be suitable for treatment of other diseases, such as stroke and ischaemia–reperfusion injury.
USP29 enhances chemotherapy-induced stemness in non-small cell lung cancer via stabilizing Snail1 in response to oxidative stress
Authors: Wu Yueguang , Zhang Yingqiu , Wang Duchuang , Zhang Yang , Zhang Jinrui , Zhang Yayun , Xu Lu , Wang Taishu , Wang Shanshan , Zhang Qingqing , Liu Fang , Zaky Mohamed Y. , Li Qiong , Sun Qianhui , Guo Dong , Liu Shuyan , Zou Lijuan , Yang Qingkai , Liu Han
Published: September 2020

Chemotherapy remains an essential part of diverse treatment regimens against human malignancies. However, recent progressions have revealed a paradoxical role of chemotherapies to induce the cancer stem cell-like features that facilitate chemoresistance and tumor dissemination, with the underlying mechanisms underinvestigated. The zinc-finger transcription factor Snail1 is a central regulator during the epithelial-mesenchymal transition process and is closely implicated in cancer progression. Snail1 expression is strictly regulated at multiple layers, with its stability governed by post-translational ubiquitylation that is counterbalanced by the activities of diverse E3 ligases and deubiquitylases. Here we identify the deubiquitylase USP29 as a novel stabilizer of Snail1, which potently restricts its ubiquitylation in a catalytic activity-dependent manner. Bioinformatic analysis reveals a reverse correlation between USP29 expression and prognosis in lung adenocarcinoma patients. USP29 is unique among Snail1 deubiquitylases through exhibiting chemotherapy-induced upregulation. Mechanistically, oxidative stresses incurred by chemotherapy stimulate transcriptional activation of USP29. USP29 upregulation enhances the cancer stem cell-like characteristics in lung adenocarcinoma cells to promote tumorigenesis in athymic nude mice. Our findings uncover a novel mechanism by which chemotherapy induces cancer stemness and suggest USP29 as a potential therapeutic target to impede the development of chemoresistance and metastasis in lung adenocarcinoma.
A lysozyme with altered substrate specificity facilitates prey cell exit by the periplasmic predator Bdellovibrio bacteriovorus
Authors: Harding Christopher J. , Huwiler Simona G. , Somers Hannah , Lambert Carey , Ray Luke J. , Till Rob , Taylor Georgina , Moynihan Patrick J. , Sockett R. Elizabeth , Lovering Andrew L.
Published: September 2020

Lysozymes are among the best-characterized enzymes, acting upon the cell wall substrate peptidoglycan. Here, examining the invasive bacterial periplasmic predator Bdellovibrio bacteriovorus, we report a diversified lysozyme, DslA, which acts, unusually, upon (GlcNAc-) deacetylated peptidoglycan. B. bacteriovorus are known to deacetylate the peptidoglycan of the prey bacterium, generating an important chemical difference between prey and self walls and implying usage of a putative deacetyl-specific “exit enzyme”. DslA performs this role, and ΔDslA strains exhibit a delay in leaving from prey. The structure of DslA reveals a modified lysozyme superfamily fold, with several adaptations. Biochemical assays confirm DslA specificity for deacetylated cell wall, and usage of two glutamate residues for catalysis. Exogenous DslA, added ex vivo, is able to prematurely liberate B. bacteriovorus from prey, part-way through the predatory lifecycle. We define a mechanism for specificity that invokes steric selection, and use the resultant motif to identify wider DslA homologues.
Autonomous mesoscale positioning emerging from myelin filament self-organization and Marangoni flows
Authors: van der Weijden Arno , Winkens Mitch , Schoenmakers Sandra M. C. , Huck Wilhelm T. S. , Korevaar Peter A.
Published: September 2020

Out-of-equilibrium molecular systems hold great promise as dynamic, reconfigurable matter that executes complex tasks autonomously. However, translating molecular scale dynamics into spatiotemporally controlled phenomena emerging at mesoscopic scale remains a challenge—especially if one aims at a design where the system itself maintains gradients that are required to establish spatial differentiation. Here, we demonstrate how surface tension gradients, facilitated by a linear amphiphile molecule, generate Marangoni flows that coordinate the positioning of amphiphile source and drain droplets floating at air-water interfaces. Importantly, at the same time, this amphiphile leads, via buckling instabilities in lamellar systems of said amphiphile, to the assembly of millimeter long filaments that grow from the source droplets and get absorbed at the drain droplets. Thereby, the Marangoni flows and filament organization together sustain the autonomous positioning of interconnected droplet-filament networks at the mesoscale. Our concepts provide potential for the development of non-equilibrium matter with spatiotemporal programmability.
Design of highly efficient deep-blue organic afterglow through guest sensitization and matrices rigidification
Authors: Xu Shen , Wang Wu , Li Hui , Zhang Jingyu , Chen Runfeng , Wang Shuang , Zheng Chao , Xing Guichuan , Song Chunyuan , Huang Wei
Published: September 2020

Blue/deep-blue emission is crucial for organic optoelectronics but remains a formidable challenge in organic afterglow due to the difficulties in populating and stabilizing the high-energy triplet excited states. Here, a facile strategy to realize the efficient deep-blue organic afterglow is proposed via host molecules to sensitize the triplet exciton population of guest and water implement to suppress the non-radiative decays by matrices rigidification. A series of highly luminescent deep-blue (405–428 nm) organic afterglow materials with lifetimes up to 1.67 s and quantum yields of 46.1% are developed. With these high-performance water-responsive materials, lifetime-encrypted rewritable paper has been constructed for water-jet printing of high-resolution anti-counterfeiting patterns that can retain for a long time (>1 month) and be erased by dimethyl sulfoxide vapor in 15 min with high reversibility for many write/erase cycles. These results provide a foundation for the design of high-efficient blue/deep-blue organic afterglow and stimuli-responsive materials with remarkable applications.
Structural dynamics of basaltic melt at mantle conditions with implications for magma oceans and superplumes
Authors: Majumdar Arnab , Wu Min , Pan Yuanming , Iitaka Toshiaki , Tse John S.
Published: September 2020

Transport properties like diffusivity and viscosity of melts dictated the evolution of the Earth’s early magma oceans. We report the structure, density, diffusivity, electrical conductivity and viscosity of a model basaltic (Ca11Mg7Al8Si22O74) melt from first-principles molecular dynamics calculations at temperatures of 2200 K (0 to 82 GPa) and 3000 K (40–70 GPa). A key finding is that, although the density and coordination numbers around Si and Al increase with pressure, the Si–O and Al–O bonds become more ionic and weaker. The temporal atomic interactions at high pressure are fluxional and fragile, making the atoms more mobile and reversing the trend in transport properties at pressures near 50 GPa. The reversed melt viscosity under lower mantle conditions allows new constraints on the timescales of the early Earth’s magma oceans and also provides the first tantalizing explanation for the horizontal deflections of superplumes at ~1000 km below the Earth’s surface.
Facile decoding of quantitative signatures from magnetic nanowire arrays
Authors: Zamani Kouhpanji Mohammad Reza , Ghoreyshi Ali , Visscher P. B. , Stadler Bethanie J. H.
Published: September 2020

Magnetic nanoparticles have been proposed as contact-free minimal-background nanobarcodes, and yet it has been difficult to rapidly and reliably decode them in an assembly. Here, high aspect ratio nanoparticles, or magnetic nanowires (MNWs), are characterized using first-order reversal curves (FORC) to investigate quantitative decoding. We have synthesized four types of nanowires (differing in diameter) that might be used for barcoding, and identified four possible “signature” functions that might be used to quickly distinguish them. To test this, we have measured the signatures of several combination samples containing two or four different MNW types, and fit them to linear combinations of the individual type signatures to determine the volume ratios of the types. We find that the signature which determines the ratios most accurately involves only the slope of each FORC at its reversal field, which requires only 2–4 data points per FORC curve, reducing the measurement time by a factor of 10 to 50 compared to measuring the full FORC.
Automated AFM analysis of DNA bending reveals initial lesion sensing strategies of DNA glycosylases
Authors: Bangalore Disha M. , Heil Hannah S. , Mehringer Christian F. , Hirsch Lisa , Hemmen Katherina , Heinze Katrin G. , Tessmer Ingrid
Published: September 2020

Base excision repair is the dominant DNA repair pathway of chemical modifications such as deamination, oxidation, or alkylation of DNA bases, which endanger genome integrity due to their high mutagenic potential. Detection and excision of these base lesions is achieved by DNA glycosylases. To investigate the remarkably high efficiency in target site search and recognition by these enzymes, we applied single molecule atomic force microscopy (AFM) imaging to a range of glycosylases with structurally different target lesions. Using a novel, automated, unbiased, high-throughput analysis approach, we were able to resolve subtly different conformational states of these glycosylases during DNA lesion search. Our results lend support to a model of enhanced lesion search efficiency through initial lesion detection based on altered mechanical properties at lesions. Furthermore, its enhanced sensitivity and easy applicability also to other systems recommend our novel analysis tool for investigations of diverse, fundamental biological interactions.
Propolis nanoparticle enhances the potency of antimicrobial photodynamic therapy against Streptococcus mutans in a synergistic manner
Authors: Afrasiabi Shima , Pourhajibagher Maryam , Chiniforush Nasim , Bahador Abbas
Published: September 2020

Less invasive removal approaches have been recommended for deep caries lesions. Antimicrobial photodynamic therapy (aPDT) and propolis nanoparticle (PNP) are highlighted for the caries management plan. Evidence is lacking for an additive effect of combination PNP with photosensitizer (PS) in aPDT. This study aimed to investigate the individual and synergistic effects of chlorophyllin-phycocyanin mixture (PhotoActive+) and toluidine blue O (TBO) as PSs in combination with PNP in the aPDT process (aPDTplus) against major important virulence factors of Streptococcus mutans. Following characterization, biocompatibility of the PSs alone, or in combination with PNP were investigated on human gingival fibroblast cell. The in vitro synergy of PhotoActive+ or TBO and PNP was evaluated by the checkerboard method. The bacteria's virulence properties were surveyed in the presence of the PSs, individually as well as in combination. When the PSs were examined in combination (synergistic effect, FIC Index < 0.5), a stronger growth inhibitory activity was exhibited than the individual PSs. The biofilm formation, as well as genes involved in biofilm formation, showed greater suppression when the PSs were employed in combination. Overall, the results of this study suggest that the combination of PhotoActive+ or TBO with PNP with the least cytotoxicity effects and the highest antimicrobial activites would improve aPDT outcomes, leading to synergistic effects and impairing the virulence of S. mutans.
A higher-order finite element reactive transport model for unstructured and fractured grids
Authors: Moortgat Joachim , Li Mengnan , Amooie Mohammad Amin , Zhu Di
Published: September 2020

This work presents a new reactive transport framework that combines a powerful geochemistry engine with advanced numerical methods for flow and transport in subsurface fractured porous media. Specifically, the PhreeqcRM interface (developed by the USGS) is used to take advantage of a large library of equilibrium and kinetic aqueous and fluid-rock reactions, which has been validated by numerous experiments and benchmark studies. Fluid flow is modeled by the Mixed Hybrid Finite Element (FE) method, which provides smooth velocity fields even in highly heterogenous formations with discrete fractures. A multilinear Discontinuous Galerkin FE method is used to solve the multicomponent transport problem. This method is locally mass conserving and its second order convergence significantly reduces numerical dispersion. In terms of thermodynamics, the aqueous phase is considered as a compressible fluid and its properties are derived from a Cubic Plus Association (CPA) equation of state. The new simulator is validated against several benchmark problems (involving, e.g., Fickian and Nernst-Planck diffusion, isotope fractionation, advection-dispersion transport, and rock-fluid reactions) before demonstrating the expanded capabilities offered by the underlying FE foundation, such as high computational efficiency, parallelizability, low numerical dispersion, unstructured 3D gridding, and discrete fraction modeling.
Is there a close association of depression with either constipation or dysosmia in Parkinson’s disease?
Authors: Chang Ting-Ya , Chen Yi-Huei , Chang Ming-Hong , Lin Ching-Heng
Published: September 2020

A possible association between depression and either the severity of constipation or dysosmia in Parkinson’s disease (PD) patients was investigated in this cross-sectional study. One-hundred six patients who had the history of PD for less than 5 years were recruited. Depression was measured using the Beck Depression Inventory-II (BDI-II), and our patients were divided into depressive and non-depressive groups (DP: BDI-II ≥ 14; n = 22 and NDP: BDI-II < 14; n = 84). Olfactory dysfunction was assessed by the University of Pennsylvania Smell Identification Test (UPSIT). Constipation severity was defined by stool softener dosage and amount. Statistical analyses with one-tailed T- or chi-squared test, odds ratios (OR), and beta-coefficient were used to determine significant differences. Total scores based on the Unified Parkinson’s Disease Rating Scale (UPDRS) were significantly higher in the DP group. A significant relationship was observed between PD patients with depression and severe constipation; PD patients with depression were more likely to present with severe constipation (OR 5.81; 95% CI 1.24–27.29, p = 0.026, adjusted for age and gender); but the significance became marginal after adjusted for age, gender and UPDRS part 3 (OR 4.46, 95% CI 0.93–21.33; p = 0.061). However, no association between olfactory dysfunction and depression was detected. There were significant positive correlations between BDI-II scores and severe constipation (β ± SE 7.65 ± 2.02; p =  < 0.001, adjusted for age and gender; β ± SE 7.06 ± 2.04; p = 0.001, adjusted for age, gender, and UPDRS-3). Besides, we detected a marginally significant correlation that PD patients with higher BDI-II scores tended to present more severe motor symptoms. Olfactory dysfunction seemed to be less relevant to BDI-II scores. Based on our findings, we speculate that depression may be more closely related to brainstem nuclei than to the limbic pathway.
Synchrotron-based FTIR microspectroscopy of protein aggregation and lipids peroxidation changes in human cataractous lens epithelial cells
Authors: Kreuzer Martin , Dučić Tanja , Hawlina Marko , Andjelic Sofija
Published: September 2020

Cataract is the leading cause of blindness worldwide but the mechanisms involved in the process of cataractogenesis are not yet fully understood. Two most prevalent types of age-related cataracts are nuclear (N) and cortical (C) cataracts. A common environmental factor in most age-related cataracts is believed to be oxidative stress. The lens epithelium, the first physical and biological barrier in the lens, is build from lens epithelial cells (LECs). LECs are important for the maintenance of lens transparency as they control energy production, antioxidative mechanisms and biochemical transport for the whole lens. The purpose of this study is to characterize compounds in LECs originated from N and C cataracts, by using the synchrotron radiation-based Fourier Transform Infrared (SR-FTIR) microspectroscopy, in order to understand the functional importance of their different bio-macromolecules in cataractogenesis. We used the SR-FTIR microspectroscopy setup installed on the beamline MIRAS at the Spanish synchrotron light source ALBA, where measurements were set to achieve single cell resolution, with high spectral stability and high photon flux. The results showed that protein aggregation in form of fibrils was notably pronounced in LECs of N cataracts, while oxidative stress and the lipids peroxidation were more pronounced in LECs of C cataracts.