bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Nano Zinc Oxide Particles on Color Stability of MDX4-4210 Silicone Prostheses
Authors: Charoenkijkajorn Dittaya , Sanohkan Sasiwimol
Published: September 2020

Objective This article aimed to study the effect of different concentrations of nano zinc oxide particles on the color change of MDX4–4210 facial silicone elastomer after artificial aging.

Materials and Methods Silicone specimens (N = 150) were fabricated by incorporating intrinsic pigments and divided into three groups—white, yellow, and red, each group consisting of 50 specimens (n = 50). In each color, specimens were subdivided into five subgroups according to the quantity of zinc oxide nanoparticles (0, 0.5, 1.0, 1.5, and 2.0% weight), where the 0% weight served as the control in each group. All specimens were then subjected to artificial aging using an accelerated aging machine chamber for 12, 24, 48, and 72 hours. L*a*b* values of specimens were noted after a different aging period by a spectrophotometer and ∆E* was calculated.

Statistical Analysis Two-way repeated analysis of variance (ANOVA) was done to examine the effects under test conditions (concentration and aging time) of each color group. Then color, concentration, and the aging period were subjected to three-way repeated ANOVA to investigate the effects of different colors and concentrations on ∆E*. Bonferroni’s test was performed to identify differences between groups. The significant level was at p = 0.05.

Results The control group showed significantly higher ∆E* values than the test groups. The 1.5% test group showed significantly lower ∆E* compared with the others. The 0.5 to 2.0% of nano zinc oxide significantly decreased the color change of the silicone elastomer (p < 0.05), but there were no significant differences among groups.

Conclusions Incorporation of 1.5% of nano zinc oxide can improve the color stability of silicone prosthesis (MDX4–4210).
Noninvasive Cardiac Output Monitoring in Newborn with Hypoplastic Left Heart Syndrome
Authors: Gatelli Italo Francesco , Vitelli Ottavio , Chiesa Gaia , De Rienzo Francesca , Martinelli Stefano
Published: September 2020

Objective This study aimed to describe the first two cases of electrical cardiometry applied to newborn with hypoplastic left heart syndrome for hemodynamical assessment in the first days of life before surgical correction and see if this can help decision making process in these patients.

Study Design We describe two case series of two full-term newborn with hypoplastic left heart syndrome in the Neonatal Intensive Care Unit, ASST Grande Ospedale Metropolitano Niguarda, between December 2019 and January 2020.

Results Case 1 was persistently hemodynamically stable with prostaglandin E1 infusion at 0.01 mcg/kg/min, showing good capillary refill time, good diuresis, no difference between pre- and postductal values of oxygen saturation or blood pressure. Electrical cardiometry monitoring constantly showed cardiac output values higher than 300 mL/kg/min. Case 2 showed poor clinical condition needing prostaglandin E1 infusion up to 0.05 mcg/kg/min, intubation and septostomy associated with low cardiac output around 190 mL/kg/min. Once cardiac output has begun to rise and reached values constantly over 300 mL/kg/min, clinical condition improved with amelioration in oxygen saturation, diuresis, blood pressure, and blood gas analysis values. She was then extubated and finally clinically stable until surgery with minimal infusion of prostaglandin E1 at 0.01 mcg/kg/min.

Conclusion This case highlights how hemodynamic information provided by electrical cardiometry can be used to supplement the combined data from all monitors and the clinical situation to guide therapy in these newborns waiting surgery.

Key Points
Factors Associated with the Complications of Hysteroscopic Myomectomy
Authors: Lima Mariana Patelli Juliani de Souza , Costa-Paiva Lúcia , Brito Luiz Gustavo Oliveira , Baccaro Luiz Francisco
Published: September 2020

Objective To evaluate the factors associated with complete myomectomy in a single surgical procedure and the aspects related to the early complications.

Methods A cross-sectional study with women with submucous myomas. The dependent variables were the complete myomectomy performed in a single hysteroscopic procedure, and the presence of early complications related to the procedure.

Results We identified 338 women who underwent hysteroscopic myomectomy. In 89.05% of the cases, there was a single fibroid to be treated. According to the classification of the International Federation of Gynecology and Obstetrics (Fédération Internationale de Gynécologie et d'Obstétrique, FIGO, in French), most fibroids were of grade 0 (66.96%), followed by grade 1 (20.54%), and grade 2 (12.50%). The myomectomies were complete in 63.31% of the cases, and the factors independently associated with complete myomectomy were the diameter of the largest fibroid (prevalence ratio [PR]: 0.97; 95% confidence interval [95%CI]: 0.96–0.98) and the classification 0 of the fibroid according to the FIGO (PR: 2.04; 95%CI: 1.18–3.52). We observed early complications in 13.01% of the hysteroscopic procedures (4.44% presented excessive bleeding during the procedure, 4.14%, uterine perforation, 2.66%, false route, 1.78%, fluid overload, 0.59%, exploratory laparotomy, and 0.3%, postoperative infection). The only independent factor associated with the occurrence of early complications was incomplete myomectomy (PR: 2.77; 95%CI: 1.43–5.38).

Conclusions Our results show that hysteroscopic myomectomy may result in up to 13% of complications, and the chance of complete resection is greater in small and completely intracavitary fibroids; women with larger fibroids and with a high degree of myometrial penetration have a greater chance of developing complications from hysteroscopic myomectomy.
The Spanish National Network “Grupo Castrillo”: 22 Years of Nationwide Neonatal Infection Surveillance
Authors: Fernandez Colomer Belen , Cernada Badia Maria , Coto Cotallo Daniel , Lopez Sastre Jose ,   Grupo Castrillo Network
Published: September 2020

Objective This study aimed to describe the epidemiology of vertically transmitted sepsis (VS) and nosocomial sepsis (NOS) in very low birth weight (VLBW) neonates (birth weight ≤ 1,500 g) over the past 22 years in Spain.

Study Design This is a retrospective analysis of prospectively collected VS and NOS in neonates from 1996 to 2018 in the 44 neonatal units integrated in the Spanish Neonatal Network Grupo Castrillo.

Results A total of 2,676 episodes of VS were recorded in 2,196,129 live births (LBs; 1.2/1,000 LBs) over the study period (1996–2018). The incidence declined from 2.4 to 1 to 1.2/1,000 LBs (p < 0.0001). Of the 2,676 episodes, 95.7% were early onset (≤72 hours) and 4.3% cases late onset VS. Group B streptococcus (GBS) (33.1%) and E. coli (29.3%) were the most frequently isolated pathogen. The GBS incidence declined significantly from 1.25 to 0.21/1,000 LBs (p < 0.0001). E. coli incidence showed a significant increase trend in VLBW infants (p < 0.05). The global mortality per 1000 LBs decreased from 0.21 to 0.13/1,000. A total of 7,036 episodes of NOS involving 5,493 VLBW infants were registered over 20,935 neonatal admissions (NAs) in the study period (2006–2018). The incidence was 26.2 per 100 NAs. The median postnatal age at onset was 13 days (interquartile range [IQR]: 9–23 days). Around 80% of cases occurred in infants with a central line in place. Gram positive (GP) bacteria accounted for 66.2% with Staphylococcus epidermidis as the most frequently isolated pathogen, gram negative (GN) bacteria entailed 27.4%, and fungi 6.2%. Klebsiella sp. was the most common GN isolated and Candida albicans the most prevalent fungus. The overall mortality was 8.3%.

Conclusion The causative pathogen of neonatal sepsis may change over time and between countries, therefore a national surveillance network based on a consensus definition could be essential to provide accurate information.

Key Points
Impact of COVID-19 on Lung Transplant Activity in Germany—A Cross-Sectional Survey
Authors: Michel Sebastian , Witt Christian , Gottlieb Jens , Aigner Clemens
Published: September 2020

The current COVID-19 pandemia affects health care systems worldwide, however, to a variable extent depending on the caseload in each country. We aimed to provide a cross-sectional overview of current limitations or adaptions in lung transplant programs in Germany in from January to May 2020 due to the COVID-19 pandemia caused by severe acute respiratory syndrome coronavirus 2. A cross-sectional survey assessing various aspects of lung transplant activity was sent to all active lung transplant programs (n = 12) in Germany. Eight centers (66%) responded to the survey within the requested time frame. Four centers (50%) reported their activity is not restricted at all and four centers (50%) reported on moderate general limitations. The overall lung transplant activity in Germany from January to May 2020 contains 128 bilateral and 11 single lung transplantations, which is similar to the same period in the year 2019 (126 bilateral transplantations and 12 single lung transplantations). The results suggest that the influence of the COVID-19 pandemia on lung transplantation activity in Germany has been moderate so far. Nevertheless, adaptions such as extensive testing of donors and recipients were introduced to reduce the likelihood of infections and increase patient safety. Alertness to changes in COVID-19 reproduction rates might be required until effective antiviral therapy or vaccination is available.
Validation of an Instrument for Real-Time Assessment of Neonatal Intubation Skills: A Randomized Controlled Simulation Study
Authors: Kuijpers Lindie J.M.K. , Binkhorst Mathijs , Yamada Nicole K. , Bouwmeester Romy N. , van Heijst Arno F.J. , Halamek Louis P. , Hogeveen Marije
Published: September 2020

Objective This study aimed to evaluate the construct validity and reliability of real-time assessment of a previously developed neonatal intubation scoring instrument (NISI).

Study Design We performed a randomized controlled simulation study at a simulation-based research and training facility. Twenty-four clinicians experienced in neonatal intubation (“experts”) and 11 medical students (“novices”) performed two identical elective intubations on a neonatal patient simulator. Subjects were randomly assigned to either the intervention group, receiving predefined feedback between the two intubations, or the control group, receiving no feedback. Using the previously developed NISI, all intubations were assessed, both in real time and remotely on video. Construct validity was evaluated by (1) comparing the intubation performances, expressed as percentage scores, with and without feedback, and (2) correlating the intubation performances with the subjects' level of experience. The intrarater reliability, expressed as intraclass correlation coefficient (ICC), of real-time assessment compared with video-based assessment was determined.

Results The intervention group contained 18 subjects, the control group 17. Background characteristics and baseline intubation scores were comparable in both groups. The median (IQR) change in percentage scores between the first and second intubation was significantly different between the intervention and control group (11.6% [4.7–22.8%] vs. 1.4% [0.0–5.7%], respectively; p = 0.013). The 95% CI for this 10.2% difference was 2.2 to 21.4%. The subjects' experience level correlated significantly with their percentage scores (Spearman's R = 0.70; p <0.01). ICC's were 0.95 (95% CI: 0.89–0.97) and 0.94 (95% CI: 0.89–0.97) for the first and second intubation, respectively.

Conclusion Our NISI has construct validity and is reliable for real-time assessment.

Key Points
Bleaching Stained Arrested Caries Lesions: In vivo Clinical Study
Authors: Al-Angari Sarah S. , AlHadlaq Mashael , Abahussain Noor , AlAzzam Njood
Published: September 2020

Objective Conservative approaches to esthetically treat stained arrested caries lesions (s-ACLs) have not been explored in clinical studies. This study aims to investigate the efficacy of in-office dental bleaching agent, as a conservative approach, to esthetically treat s-ACLs.

Materials and Methods Twelve patients (n = 46) presented with s-ACLs were treated with 40% hydrogen peroxide (in-office bleaching protocol; 20 minutes × 3). Color values were measured using a spectrophotometer (CIE L*a*b*), aided with digital photography to assess visual color change clinically. Measurements were taken for each specimen at baseline and immediately after bleaching.

Statistical Analysis The color change calculated before and after bleaching for each dental substrate was analyzed using paired t-test (α = 0.05).

Results The bleached s-ACLs had a significant increase in L* values (p < 0.001), and a significant decrease in both a* (p = 0.001) and b* (p = 0.007) values, indicating lighter color improvement (bleaching efficacy). The baseline mean of L*, a*, and b* values were 61.5, 2, and 15.4, respectively, and after bleaching were 67.7, 1.4, and 13.3, respectively, with a mean increase in ∆E of >7.9, which resulted in a visible clinical stain improvement as orange/light brown stains were removed completely, while gray/black stains improved to a lesser extent.

Conclusion Significant color improvement was observed when the in-office bleaching protocol (40% hydrogen peroxide) was used in orange/brown s-ACLs. However, it showed lesser improvement in gray/black s-ACLs.
Tarsocrural Instability in Cats: Combined Internal Repair and Transarticular External Skeletal Fixation
Authors: Hammer Meike , Irubetagoyena Iban , Grand Jean-Guillaume
Published: September 2020

Objective The aim of this study was to report outcomes after combined internal repair and transarticular external skeletal fixation (TESF) for the treatment of tarsocrural joint instabilities (TCI) in cats.

Materials and Methods Open reduction of the tarsal joint was performed followed by combined (1) internal repair (tibial/ fibular malleolar osteosynthesis or primary ligament suture and/or prosthetic ligament repair) and (2) temporary TESF. Stability of the tarsus was determined at short-term follow-up (4–8 weeks postoperatively). Short-term complications were evaluated and midterm outcome assessed by an owner telephone questionnaire.

Results Fourteen cats were included of which nine had open TCI. Median time for frame removal was 47 days. Eleven patients had satisfactory stability of the tarsus at short-term follow-up. Catastrophic complications occurred in three cats consisting of extensive skin necrosis of the paw with subsequent hindlimb amputation in two and multiple digit amputations in one cat. Major complications occurred in one cat with persistent TCI requiring pantarsal arthrodesis. Nine cat owners indicated a ‘full or acceptable’ outcome at midterm (median, 1.5 years).

Conclusion Close monitoring in the postoperative period until TESF removal is important for early identification of complications. Despite good joint stability at short-term, persistent or recurrent lameness at midterm can occur.
Nurses’ Knowledge on Prevention of Catheter-Associated Urinary Tract Infection in a Selected Hospital of Mangaluru
Authors: Benny Anns M. , Idiculla Anju S. , Kunjumon Annmary , George Anuja , A. Anusha Roseline , Sequera Sonia K.L.
Published: September 2020

Introduction Catheter-associated urinary tract infection (CAUTI) is one of the most common health care–acquired infections encountered in clinical practice. The most important predisposing factor for CAUTI is the insertion and prolonged use of indwelling urinary catheter, which has been performed by unsterile technique, and by not taking adequate measures to maintain cleanliness of the catheter. This study aimed to assess the knowledge on prevention of CAUTI among staff nurses in a selected hospital of Mangaluru.

Materials and Methods Staff nurses working in medical college hospital with National Accreditation Board of Hospitals and Healthcare Providers accreditation were included in this cross-sectional descriptive study. Structured knowledge questionnaire was used to assess nurses’ knowledge on CAUTI. Frequency, percentage, mean, standard deviation, and Chi-square test were used for association.

Results Majority of nurses (80.85%) had average knowledge on prevention of CAUTI, whereas 11.2% nurses had low knowledge and few (7.231%) nurses had high knowledge regarding CAUTI. Association was found between knowledge and age (0.013), educational qualification (0.018), and encounter with patients with CAUTI (0.00) is <0.05, at 0.05 level of significance

Conclusion Pooled results showed that majority of the nurses had average knowledge on prevention of CAUTI.
Putative Clinical Implications of Unilateral Ossified Sacrospinous Ligament
Authors: Siddiqui Abu Ubaida , Gurudiwan Richa , Siddiqui Abu Talha , Gupta Paritosh , Singh Jivtesh
Published: September 2020

Introduction Sacrospinous ligament (SSL) is a thin structure that extends from the ischial spine to the lateral margins of sacrum and coccyx, anterior to the Sacrotuberous ligament (STL). The internal pudendal and inferior gluteal vessels, pudendal nerve, sciatic nerve, and other branches of sacral nerve plexus pass through the greater sciatic foramen (GSF) in close proximity to the ischial spine and SSL.

Objective This study aimed to report a case encountered during the routine osteology tutorial, where one of the pelvises presented with ossified SSL on the right side along with ossification of lumbosacral and the sacroiliac joints.

Case Report The SSL of the right side of the pelvis was completely ossified, extending between the ischial spine and fifth piece of sacrum. The ossification had a broad-based origin from the sacrum and tapered as in proceeded to the ischial spine. It was attached to the ischial spine with a slight enlargement. Moreover, the lumbosacral and the sacroiliac joints also appeared to be ossified.

Conclusion Ossification of the SSL can restrict the lesser sciatic foramen and the greater sciatic foramen, thus causing compression of neurovascular structures traversing these areas. This can be the causative factor in pudendal nerve/sciatic nerve entrapment and can be a cause for undiagnosed chronic perineal pain. Proper anatomical knowledge and radiologic studies can be utilized for accurate diagnosis and treatment of neurovascular compression syndromes and also during reconstructive procedures of the pelvic floor and treatment of uterovaginal prolapse.
Embodiment and Presence in Virtual Worlds: A Review
Authors: Schultze Ulrike
Published: September 2020

The multimodal, 3D-graphlcal communication platforms known as virtual worlds have their historical roots In multi-user domains/dungeons (MUDs) and virtual reality (VR). Given the extensive research on these technologies and the novelty of virtual worlds as a topic of study In Information systems (IS), It behooves us to learn from the concepts, theories and Insights generated primarily by other disciplines that have focused on these technologies. Because neither MUDs nor VR have significant organizational application, thus locating them outside of the IS discipline's purview, very little of this literature has found Its way Into IS research thus far. This article reviews the extant literature on virtual environments and seeks to make Its Insights accessible to IS research on virtual worlds. In particular, this will focus on concepts, theories and Insights regarding embodiment and presence, which are afforded by the avatar, a distinguishing technological artifact of virtual worlds.
Dirac structures in nonequilibrium thermodynamics for simple open systems
Authors: Gay-Balmaz François , Yoshimura Hiroaki
Published: September 2020

Dirac structures are geometric objects that generalize Poisson structures and presymplectic structures on manifolds. They naturally appear in the formulation of constrained mechanical systems and play an essential role in structuring a dynamical system through the energy flow between its subsystems and elements. In this paper, we show that the evolution equations for open thermodynamic systems, i.e., systems exchanging heat and matter with the exterior, admit an intrinsic formulation in terms of Dirac structures. We focus on simple systems in which the thermodynamic state is described by a single entropy variable. A main difficulty compared to the case of closed systems lies in the explicit time dependence of the constraint associated with entropy production. We overcome this issue by working with the geometric setting of time-dependent nonholonomic mechanics. We define two types of Dirac dynamical systems for the nonequilibrium thermodynamics of open systems, based either on the generalized energy or the Lagrangian. The variational formulations associated with the Dirac dynamical systems are also presented.
Positive bias temperature instability of HfO2-based gate stacks at reduced thermal budget for future CMOS technologies
Authors: Claes D. , Franco J. , Collaert N. , Linten D. , Heyns M.
Published: September 2020

CMOS technology has always exploited the high thermal stability of Si, which enables high temperature fabrication steps for various device improvements, in particular, for curing oxide defects and hence improving the device stability and reliability. However, with the rise of novel device and architecture concepts such as sequential 3D stacking of Si CMOS tiers in a monolithic integration flow, or the introduction of high-mobility Ge/III–V channels, this paradigm cannot be maintained, and the entire fabrication flow will have to be enabled at a reduced thermal budget. We investigate the current industry standard high-k dielectric, HfO2, showing how its charge trapping behavior evolves when reducing the overall fabrication thermal budget, affecting the positive bias temperature instability (PBTI) of the device. We perform this study focusing on thermal budget ranges of relevance for gate stack development compatible with future technologies. Our finding of reduced reliability at lower thermal budgets (especially <300 °C) is explained in terms of changes in the oxide defect bands, as suggested by physics-based charge trapping modeling. Our results support the hypothesis of multiple microscopic defects contributing to PBTI in HfO2: for low fabrication thermal budgets, the stretched Hf–O–Hf bonds might dominate the charge trapping kinetics, while with post-deposition anneal at temperatures >400 °C, oxygen vacancies might become the dominant species.
Research on effects of space charge field in relativistic backward wave oscillator
Authors: Wu Ping , Sun Jun , Cao Yibing , Fan Zhiqiang , Chen Changhua
Published: September 2020

The breakdown problem in the relativistic backward wave oscillator (RBWO) limits the microwave pulse energy and should be solved. The slow wave structure (SWS) is the most key component of the RBWO. The breakdown of SWS may be triggered by field-induced electron emission and electron bombardment on the wall. This paper demonstrates that the space charge field of the relativistic electron beam (REB) can enhance the electric field forbidding field-induced electron emission and decrease the electric field igniting the RF breakdown, and therefore, the RF breakdown can be significantly suppressed. However, the enhanced electric field will enlarge the radial displacements of electrons, especially the high-energy electrons. When the RBWO operates with a low guiding magnetic field or a long-pulse REB, this situation will worsen and some electrons may possess large enough radial displacements and bombard on the SWS surface with the help of radial oscillation of REB and radial expansion of cathode plasmas. This may aggravate the breakdown of SWS.
Extended magnetohydrodynamics simulations of thin-foil Z-pinch implosions with comparison to experiments
Authors: Woolstrum J. M. , Yager-Elorriaga D. A. , Campbell P. C. , Jordan N. M. , Seyler C. E. , McBride R. D.
Published: September 2020

Cylindrical foil liners, with foil thicknesses on the order of 400 nm, are often used in university-scale Z-pinch experiments (∼1 MA in 100 ns) to study physics relevant to inertial confinement fusion efforts on larger-scale facilities (e.g., the magnetized liner inertial fusion effort on the 25-MA Z facility at Sandia National Laboratories). The use of ultrathin foil liners typically requires a central support rod to maintain the structural integrity of the liner target assembly prior to implosion. The radius of this support rod sets a limit on the maximum convergence ratio achievable for the implosion. In recent experiments with a support rod and a pre-imposed axial magnetic field, helical instability structures in the imploding foil plasma were found to persist as the foil plasma stagnated on the rod and subsequently expanded away from the rod [Yager-Elorriaga et al., Phys. Plasmas 25(5), 056307 (2018)]. We have now used the 3D extended magnetohydrodynamics simulation code PERSEUS (which includes Hall physics) [C. E. Seyler and M. R. Martin, Phys. Plasmas 18(1), 012703 (2011)] to study these experiments. The results suggest that it is the support rod that is responsible for the helical structures persisting beyond stagnation. Furthermore, we find that as the radius of the support rod decreases (i.e., as the convergence ratio increases), the integrity and persistence of the helical modes diminish. In the limit with no support rod, we find that the structure of the final stagnation column is governed by the structure of the central precursor plasma column. These simulation results and their comparisons to experiment are presented.
Modification of terahertz emission spectrum using microfabricated spintronic emitters
Authors: Wu Weipeng , Lendinez Sergi , Taghipour Kaffash Mojtaba , Schaller Richard D. , Wen Haidan , Jungfleisch M. Benjamin
Published: September 2020

Terahertz (THz) radiation with sub-millimeter wavelength falls in the gap between optical and radio frequencies. Conventional THz emitters do not intertwine with spin degrees of freedom. However, it was recently shown that broadband THz radiation can be efficiently created also by exploiting spin-based effects on ultrafast time scales. Here, we demonstrate the generation and control of THz radiation from microstructured spintronic THz emitters based on the inverse spin-Hall effect. Using time-domain THz spectroscopy, we compare the THz spectra of different stripe patterns made of Fe/Pt bilayers with a spectrum obtained from an extended Fe/Pt bilayer film. It is found that the THz spectrum can be altered by a proper choice of the microstructure dimensions. The experimentally observed spectra are interpreted in terms of a simplified multi-slit interference model, which captures the main experimental features. Our results pave the way for an efficient control of THz light emitted from magnetic heterostructures. This is a crucial step forward for the design and realization of directional THz sources.
Metal to semiconductor transition of two-dimensional NbSe2 through hydrogen adsorption: A first-principles study
Authors: Yeoh K. H. , Chew K. H. , Yoon T. L. , Rusi  , Chang Y. H. R. , Ong D. S.
Published: September 2020

Based on first-principles calculations, we predict that the recently synthesized two-dimensional (2D) NbSe2 can be changed from the metallic to the semiconducting phase upon the adsorption of H with an indirect bandgap of 2.99 eV. The bandgap opening of the 2D NbSe2 only occurs when the hydrogen coverage is high, and it is sensitive to mechanical strain. The hydrogenated 2D NbSe2 is dynamically stable under a tensile strain of up to 9%, whereas a compressive strain leads to instability of the system. The optical spectra obtained from the GW-Bethe–Salpeter equation calculations suggest that 2D NbSe2 is highly isotropic, and it will not affect the polarization of light along the x- or y-direction. The optical bandgap, describing the transition energy of the exciton, is sensitive to the mechanical strain with the calculated exciton binding energy of ∼0.42 eV. These intriguing properties suggest that H functionalized 2D NbSe2, grown on a substrate with a larger lattice parameter, can be used to modulate the bandgap of NbSe2. This is beneficial in developing a nanoscale field effect and optoelectronic devices.
Sodium ion transport across the endothelial glycocalyx layer under electric field conditions: A molecular dynamics study
Authors: Jiang Xi Zhuo , Yang Lumeng , Ventikos Yiannis , Luo Kai H.
Published: September 2020

In the present research, the sodium ion transport across the endothelial glycocalyx layer (EGL) under an imposed electric field is investigated, for the first time, using a series of molecular dynamics simulations. The electric field is perpendicularly imposed on the EGL with varying strengths. The sodium ion molarity difference between the inner and outer layers of EGL, Δc, is used to quantify the sodium transport in the presence of the negatively charged glycocalyx sugar chains. Results suggest that a weak electric field increases Δc, regardless of whether the electric field is imposed perpendicularly inward or outward. By contrast, a strong electric field drives sodium ions to travel in the same orientation as the electric field. Scrutiny of the charge distribution of the glycocalyx sugar chains suggests that the electric field modifies the spatial layouts of glycocalyx atoms as it drives the transport of sodium ions. The modification in glycocalyx layouts further changes the inter-molecular interactions between glycocalyx sugar chains and sodium ions, thereby limiting the electric field control of ion transport. The sodium ions, in turn, alter the apparent bending stiffness of glycocalyx. Moreover, the negative charges of the glycocalyx sugar chains play an important role in maintaining structural stability of endothelial glycocalyx. Based on the findings, a hypothesis is proposed regarding the existence of a strength threshold of the electric field in controlling charged particles in the endothelium, which offers an alternative explanation for contrasting results in previous experimental observations.
Simulations of divertor plasmas with inverse sheaths
Authors: Masline R. , Smirnov R. D. , Krasheninnikov S. I.
Published: September 2020

The effect of strong electron emission from material surfaces has been proposed to form an “inverse sheath”: a region with a positive potential relative to the near-wall plasma which prevents the flow of ions to the wall [M. D. Campanell, “Negative plasma potential relative to electron-emitting surfaces,” Phys. Rev. E. 88, 033103 (2013); M. D. Campanell and M. V. Umansky, “Strongly emitting surfaces unable to float below plasma potential,” Phys. Rev. Lett. 116, 1–5 (2016); M. D. Campanell and G. R. Johnson, “Thermionic cooling of the target plasma to a sub-ev temperature,” Phys. Rev. Lett. 122, 1–5 (2019)]. We assess the viability of this regime in a tokamak device using the 2D edge plasma transport code UEDGE [T. Rognlien et al., “A fully implicit, time dependent 2-D fluid code for modeling tokamak edge plasmas,” J. Nucl. Mater. 196–198, 347–351 (1992)]. Since the UEDGE code does not consider the sheath region directly, we apply boundary conditions at the divertor targets which emulate the physics of both “standard” and “inverse” sheath regimes [R. Masline et al., “Influence of the inverse sheath on divertor plasma performance in tokamak edge plasma simulations,” Contrib. Plasma Phys. 60, e201900097 (2020)]. Using these boundary conditions, we perform scoping studies to assess plasma parameters near the target by varying the density at the core-edge interface. We observe a smooth transition in the resultant profiles of plasma parameters for the standard sheath, and a bifurcation across the simulation set for plasmas with an inverse sheath. The cause of this bifurcation is assessed by performing the parameter scan both with and without impurity radiation; we observe that the bifurcation persists in both cases, indicating that this bifurcation is caused by plasma recombination.
Machine learning approaches for structural and thermodynamic properties of a Lennard-Jones fluid
Authors: Craven Galen T. , Lubbers Nicholas , Barros Kipton , Tretiak Sergei
Published: September 2020

Predicting the functional properties of many molecular systems relies on understanding how atomistic interactions give rise to macroscale observables. However, current attempts to develop predictive models for the structural and thermodynamic properties of condensed-phase systems often rely on extensive parameter fitting to empirically selected functional forms whose effectiveness is limited to a narrow range of physical conditions. In this article, we illustrate how these traditional fitting paradigms can be superseded using machine learning. Specifically, we use the results of molecular dynamics simulations to train machine learning protocols that are able to produce the radial distribution function, pressure, and internal energy of a Lennard-Jones fluid with increased accuracy in comparison to previous theoretical methods. The radial distribution function is determined using a variant of the segmented linear regression with the multivariate function decomposition approach developed by Craven et al. [J. Phys. Chem. Lett. 11, 4372 (2020)]. The pressure and internal energy are determined using expressions containing the learned radial distribution function and also a kernel ridge regression process that is trained directly on thermodynamic properties measured in simulation. The presented results suggest that the structural and thermodynamic properties of fluids may be determined more accurately through machine learning than through human-guided functional forms.
Magnetic droplet solitons
Authors: Macià Ferran , Kent Andrew D.
Published: September 2020

Magnetic droplet solitons are dynamical magnetic textures that form due to an attractive interaction between spin waves in thin films with perpendicular magnetic anisotropy. Spin currents and the spin torques associated with these currents enable their formation as they provide a means to excite non-equilibrium spin-wave populations and compensate their decay. Recent years have seen rapid advances in experiments that realize and study magnetic droplets. Important advances include the first direct x-ray images of droplets, determination of their threshold and sustaining currents, measurement of their generation and annihilation time, and evidence for drift instabilities, which can limit their lifetime. This perspective discusses these studies and contrasts these solitons to other types of spin-current excitations, such as spin-wave bullets, and static magnetic textures, including magnetic vortices and skyrmions. Magnetic droplet solitons can also serve as current controlled microwave frequency oscillators with potential applications in neuromorphic chips as nonlinear oscillators with memory.
Magnetohydrodynamic self-propulsion of active matter agents
Authors: Zharov Alexander , Fierro Vanessa , Celzard Alain
Published: September 2020

Self-propelled particles, based on the magnetohydrodynamic acceleration of the surrounding fluid, are proposed for application as active matter agents. When the particles are resonantly excited by an electromagnetic wave, the scattered electric field induces currents in the surrounding fluid, which interact with the scattered magnetic field, thus producing a thrust. The time-averaged force is generally non-zero and can provide steady motion. Both the orientation of the particle and the direction of motion can be controlled by the radiation frequency and polarization. The concept has been studied analytically and through simulations showing its feasibility.
Unfolding the prospects of computational (bio)materials modeling
Authors: Sevink G. J. Agur , Liwo Jozef Adam , Asinari Pietro , MacKernan Donal , Milano Giuseppe , Pagonabarraga Ignacio
Published: September 2020

In this perspective communication, we briefly sketch the current state of computational (bio)material research and discuss possible solutions for the four challenges that have been increasingly identified within this community: (i) the desire to develop a unified framework for testing the consistency of implementation and physical accuracy for newly developed methodologies, (ii) the selection of a standard format that can deal with the diversity of simulation data and at the same time simplifies data storage, data exchange, and data reproduction, (iii) how to deal with the generation, storage, and analysis of massive data, and (iv) the benefits of efficient “core” engines. Expressed viewpoints are the result of discussions between computational stakeholders during a Lorentz center workshop with the prosaic title Workshop on Multi-scale Modeling and are aimed at (i) improving validation, reporting and reproducibility of computational results, (ii) improving data migration between simulation packages and with analysis tools, (iii) popularizing the use of coarse-grained and multi-scale computational tools among non-experts and opening up these modern computational developments to an extended user community.
Occurrence of oscillatory modes in a diode with counter-streaming electron and ion flows
Authors: Kuznetsov V. I. , Flegontova E. Yu. , Bakaleinikov L. A.
Published: September 2020

Plasma devices, as well as some astrophysical objects, are often characterized by the presence of the counterstreaming flows of electrons and positively charged particles in the plasma. In such diodes, more than one stationary solution is possible for the same set of diode parameters. In this paper, we have studied the stability of the most complex solutions, which are characterized by the presence of the potential barriers for both electrons and ions in the plasma gap. It was discovered that there exists a threshold for the value of the electron current, above which the solutions become unstable with respect to small perturbations. In this case, the solutions with nonlinear oscillations appear in the diode instead of stationary solutions. The period of these oscillations is compared to the average time of ion flight across the plasma gap. The features of time-dependent solutions have been studied. In particular, it is found that the electron current passing through the diode in the course of oscillations exceeds that corresponding to the steady states.
Scaled recoupling of chemical shift anisotropies at high magnetic fields under MAS with interspersed C-elements
Authors: Fritzsching Keith J. , Keeler Eric G. , He Chengming , McDermott Ann E.
Published: September 2020

The power of chemical shift anisotropy (CSA) measurements for probing structure and dynamics of molecules has been long recognized. NMR pulse sequences that allow measurement of CSA values in an indirect dimension of a protein correlation spectrum have been employed for aliphatic groups, but for practical reasons, carbonyl functional groups have been little studied, despite the fact that carbonyls are expected to give particularly varied and informative CSA values. Specifically, the wide spectral widths of carbonyl tensors make their measurements difficult with typically attainable spectrometer settings. We present here an extended family of experiments that enable the recovery of static CSA lineshapes in an indirect dimension of magic angle spinning (MAS) solid-state NMR experiments, except for various real valued scaling factors. The experiment is suitable for uniformly labeled material, at moderate MAS rates (10 kHz–30 kHz) and at higher magnetic fields (ν0H > 600 MHz). Specifically, the experiments are based on pulse sequence elements from a previous commonly used pulse sequence for CSA measurement, recoupling of chemical shift anisotropy (ROCSA), while modification of scaling factors is achieved by interspersing different blocks of C-elements of the same Cnn1 cycle. Using experimental conditions similar to the parent ROCSA sequence, a CSA scaling factor between 0 and 0.272 can be obtained, thus allowing a useful practical range of possibilities in experimental conditions for measurement of larger CSA values. Using these blocks, it is also possible to make a constant-time CSA recoupling sequence. The effectiveness of this approach, fROCSA, is shown on model compounds 1-13C-Gly, U–13C,15N-l-His, and microcrystalline U–13C,15N-Ubiquitin.
Anisotropic properties of monolayer 2D materials: An overview from the C2DB database
Authors: Vannucci Luca , Petralanda Urko , Rasmussen Asbjørn , Olsen Thomas , Thygesen Kristian S.
Published: September 2020

We analyze the occurrence of in-plane anisotropy in the electronic, magnetic, elastic, and transport properties of more than 1000 2D materials from the C2DB database. We identify hundreds of anisotropic materials and classify them according to their point group symmetry and degree of anisotropy. A statistical analysis reveals that a lower point group symmetry and a larger amount of different elements in the structure favor all types of anisotropies, which could be relevant for future material design approaches. Besides, we identify novel compounds, predicted to be easily exfoliable from a parent bulk compound, with anisotropies that largely outscore those of already known 2D materials. Our findings provide a comprehensive reference for future studies of anisotropic response in atomically thin crystals and point to new previously unexplored materials for the next generation of anisotropic 2D devices.
Experimental determination of the {111}/{001} surface energy ratio for Pd crystals
Authors: Chen Peiyu , Gao Yakun , Castell Martin R.
Published: September 2020

Pd crystals grown in ultrahigh vacuum (UHV) on nanostructured SrTiO3(001) and anatase TiO2(001) thin film substrates were studied using scanning tunneling microscopy. The crystals have the equilibrium shape of a truncated octahedron with a {111} top facet, {111} and {001} side facets, and a {111} interface. A consistent crystal shape is reached only after annealing the samples in UHV at 450 °C or above. By measuring the top facet dimensions of the equilibrium crystals, we determine the ratio of the surface energies for Pd to be γ111/γ001 = 0.77 ± 0.02.
Using multiple lines of evidence to delimit protogynes and deutogynes of four-legged mites: a case study on Epitrimerus sabinae s.l. (Acari : Eriophyidae)
Authors: Yin Yue , Yao Liang-Fei , Zhang Qi , Hebert Paul D. N. , Xue Xiao-Feng
Published: September 2020

Accurate species delimitation is essential for the study of biodiversity, but morphological approaches often provide a limited ability to connect different life stages, sexes or other phenotypic variants in eriophyoid mites because many species possess two phenotypically distinct forms: protogynes and deutogynes. In this study, we analysed the morphological variation in 26 populations of the eriophyoid mite, Epitrimerus sabinae Xue & Hong, 2005 s.l., from sites across its entire known distribution and revealed three morphotypes (LNS: large, normal palp seta d; MBS: medium, bifurcated palp seta d; SBS: small, bifurcated palp seta d) distinguished by body size and structure of dorsal pedipalp genual seta. Five lines of evidence (morphometrics, DNA-based species delimitation, phylogenetics, haplotype network, mitochondrial genome architecture) indicated that the MBS and SBS groups were very distinct from LNS (E. sabinae s.s.). In fact, the MBS and SBS morphotypes are properly placed in the genus Leipothrix with the MBS lineage representing the protogyne of L. juniperensis, sp. nov., whereas the SBS lineage is its deutogyne. By expanding the approaches used to link protogynes and deutogynes of eriophyoid mites, this study provides a way to accelerate the delineation of species boundaries in this important group of plant pests.
Radiation induces dynamic changes to the T cell repertoire in renal cell carcinoma patients
Authors: Chow Jacky , Hoffend Nicholas C. , Abrams Scott I. , Schwaab Thomas , Singh Anurag K. , Muhitch Jason B.
Published: September 2020

Significance

Strong evidence supports the tumor immune landscape as a determinant of patient responses to immunotherapy. Readily available therapies, including radiation, are being investigated as modifying agents with immune checkpoint blockade. However, little is known regarding radiotherapy’s impact within the tumor microenvironment and intratumoral T cell repertoires of patients, leaving critical gaps in the guided design of clinical protocols. In this study, samples from renal cell carcinoma (RCC) patients underwent high-throughput analysis to reveal transcriptional immune activation and increased clonality in irradiated tumors. Analysis across longitudinal blood samples showed that tumor-enriched clonotypes undergo phases of peripheral expansion and contraction following radiation. Collectively, these findings demonstrate that radiotherapy remodels intratumoral T cell responses and support refined sequencing of combination strategies in RCC.
Highly infectious prions are not directly neurotoxic
Authors: Benilova Iryna , Reilly Madeleine , Terry Cassandra , Wenborn Adam , Schmidt Christian , Marinho Aline T. , Risse Emmanuel , Al-Doujaily Huda , Wiggins De Oliveira Michael , Sandberg Malin K. , Wadsworth Jonathan D. F. , Jat Parmjit S. , Collinge John
Published: September 2020

Significance

Prions are infectious agents composed of polymers of misfolded prion protein which cause fatal brain diseases such as Creutzfeldt–Jakob disease. These diseases involve progressive loss of neuronal cells, and it has been long assumed that prions are directly toxic to cells as they propagate. However, recent studies have suggested that prion infectivity and neurotoxicity can be uncoupled and involve distinct mechanisms. Using highly purified infectious prions we demonstrate that prions are not directly neurotoxic and that toxicity present in infected brain tissue can be distinguished from infectious prions. This has fundamental implications for understanding of prion diseases and how to treat them and may have wide relevance in other neurodegenerative diseases which involve propagation and spread of proteopathic seeds.
Lifestyle adaptations ofRhizobiumfrom rhizosphere to symbiosis
Authors: Wheatley Rachel M. , Ford Brandon L. , Li Li , Aroney Samuel T. N. , Knights Hayley E. , Ledermann Raphael , East Alison K. , Ramachandran Vinoy K. , Poole Philip S.
Published: September 2020

Significance

Rhizobia are soil-dwelling bacteria that form symbioses with legumes and provide biologically useable nitrogen as ammonium for the host plant. High-throughput DNA sequencing has led to a rapid expansion in publication of complete genomes for numerous rhizobia, but analysis of gene function increasingly lags gene discovery. Mariner-based transposon insertion sequencing has allowed us to characterize the fitness contribution of bacterial genes and determine those functionally important in aRhizobium–legume symbiosis at multiple stages of development.
Rapid hippocampal plasticity supports motor sequence learning
Authors: Jacobacci Florencia , Armony Jorge L. , Yeffal Abraham , Lerner Gonzalo , Amaro Edson , Jovicich Jorge , Doyon Julien , Della-Maggiore Valeria
Published: September 2020

Significance

Learning predefined sequences of actions is of everyday importance. Recent evidence suggests that improvements in performance associated with learning a motor sequence take place during the quiet rest periods interleaved with practice. This phenomenon known as micro-offline gains (MOGs) is different from offline gains in performance observed overnight. Using a multimodal—functional and structural—MRI approach, here we show that the hippocampus participates in the generation of MOGs through a mechanism reminiscent of memory reactivation. Our findings point to the involvement of the hippocampus in the reactivation of nonhippocampal memories and provide evidence for a possible common mechanism at the basis of the formation of declarative and nondeclarative memories.