bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluating humidity sensing response of graphene quantum dots synthesized by hydrothermal treatment of glucose
Authors: Khan Nouman , Nawaz Ahmad , Islam Bilal , Sayyad M Hassan , Joya Yasir Faheem , Islam Sara , Bibi Saira
Published: February 2021

Graphene quantum dots (GQDs) were prepared using a single-step hydrothermal treatment of glucose (C6H12O6) powder. X-ray diffraction patterns confirmed the random stacking or amorphous character of GQDs. Additionally, the UV-vis spectra confirmed the formation of GQDs with evident absorption peaks at 237 and 305 nm, which is attributed to π- π* and n- π* transitions correspondingly. The average size and surface roughness of graphene quantum dots were estimated by atomic force microscopy images and found to be 27.0 ± 1.0 and 2.3 nm, respectively. Afterwards, the effect of increasing relative humidity (RH) from 0%–95%, and frequency, was analyzed using the capacitive and resistive responses of synthesized GQDs. The capacitive output at 0.1 kHz revealed that initially capacitance remains constant (15.0 ± 1.0 pF) up to a humidity level ranging between 0%–50%. Likewise, capacitance also displayed stabilized behavior after frequency levels were increased i.e., 1.0 and 10 kHz, at a humidity ranging from 0%–55%. Moreover, capacitance showed a 115,455, 22,480 and 3,620% improvement from their stable values at each respective frequency level i.e., 0.1, 1.0 and 10 kHz. The capacitive sensitivity decreased to 84.20 and 96.83% at greater frequencies (1.0 and 10 kHz) in comparison to the sensitivity at 0.1 kHz facing similar variations in a humid environment. In contrast, resistance displayed an exponential decline by 99.9900, 99.9796 and 99.9925%, accordingly, when RH increases from 0 to 95% at 0.1, 1.0 and 10 kHz, respectively. However, with the rise in frequency level from 0.1 to 1.0 kHz, resistive sensitivity increased considerably to 69 and 158.5%, respectively, in two prominent humidity ranges i.e., 0 ≤ RH ≤ 25% and 25% ≤ RH ≤ 50%. A further increase in testing frequency to 10 kHz enhances the resistive sensitivity by 598.5 and 178.5% when compared with the lowest sensitivity values at two noticeable humidity levels, 0%–25% and 25%–50%. The response and recovery times of our specimen were better than most of previously fabricated GQDs and other carbon-derived nanomaterials, which makes the nano-GQDs of our study more suitable for RH sensor application.
Light-induced pyroelectric property of self-powered photodetectors based on all-inorganic perovskite quantum dots
Authors: Jin Lufan , Zhang Yating , Cao Mingxuan , Yu Yu , Chen Zhiliang , Li Yifan , Zhong Zhenggeng , Hua Xuebing , Xu Lingchao , Cai Chengyu , Hu Yongqi , Tong Xian , Yao Jianquan
Published: February 2021

All-inorganic cesium lead bromine (CsPbBr3) perovskites quantum dots (QDs) are one of the most photoelectric materials due to their high absorption coefficient, pronounced quantum-size effect, tunable optical property. Here, a self-powered PD based on all-inorganic CsPbBr3 perovskites QDs is fabricated and demonstrated. The light-induced pyroelectric effect is utilized to modulate the optoelectronic processes without the external power supply. The working mechanism of the PD is carefully investigated upon 532 nm laser illumination and the minimum recognizable response time of the self-powered PD is 1.5 μs, which are faster than those of most previously reported wurtzite nanostructure PDs. Meanwhile, the frequency and temperature independence of the self-powered PD are experimented and summarized. The self-powered PD with high performance is expected to have extensive applications in solar cell, energy harvesting, resistive random access memory.
Magnetoresistive micro-displacement sensor based on magnetorheological fluid
Authors: Li Xiaolin , Zhang Jiangtao , Shen Luyan , Qin Liming , Fu Qiang , Sun Youyi , Liu Yaqing
Published: February 2021

A novel magnetoresistance material based on magnetorheological fluid (MRF) was developed for applications in micro-displacement sensor. The MRF samples were fabricated by dispersing carbonyl iron particles (CIP) into a magnetic ion liquid (MIL) composed of 1-methylethyl ether-3-butylimidazole cation and [Fe2Cl7]− anions. The magnetoresistance characteristics were also systematically tested. It was found that the resistance value of MRF with a CIP content of 20 vol% decreased from 125 to 24.4 KΩ when increasing the magnetic field from 0 to 0.2 T. A sensor device was developed to study the displacement sensing characteristics of MRF, and found that the sensor had a high sensitivity of 0.1 Ω μm−1 and a high resolution of 10.0 μm. The excellent performance can be attributed to the low modulus and good stability of the MIL matrix, allowing for easy change of the resistance by controlling the magnetic field or displacement. In summary, these unique characters make the present MRF a promising magnetoresistance material with potential applications in displacement sensor.
Identification of multiple eigenmode growth rates towards real time detection in DIII-D and KSTAR tokamak plasmas
Authors: Liu T. , Wang Z.R. , Boyer M.D. , Munaretto S. , Wang Z.X. , Park B.-H. , Logan N.C. , Yang S.M. , Park J.-K.
Published: February 2021

The successful application of three-dimensional (3D) magnetohydrodynamic (MHD) spectroscopy enables us to identify the multi-mode eigenvalues in DIII-D and KSTAR tokamak experiments with stable plasmas. The temporal evolution of the multi-modes’ stabilities have been detected. The new method is numerically efficient allowing the real time detection of MHD modes’ stabilities during the discharge. The method performs active detection of the plasma stability by utilizing the upper and lower rows of internal non-axisymmetric coils to apply a wide variety of 3D fields. Multi-mode eigenvalues are extracted using subspace system identification of the plasma response measured by 3D-field magnetic sensors distributed at different poloidal locations. The equivalence of this new method with the one introduced by Wang (2019 Nucl. Fusion
59 024001) has been numerically corroborated. The more robust and efficient calculation developed here will enable real time monitoring of the plasma stability based on the extracted eigenvalues of stable modes.
A stable corridor for toroidal plasma compression
Authors: Brennan Dylan , Froese Aaron , Reynolds Meritt , Barsky Sandra , Wen Alex , Wang Zhirui , Delage Michael , Laberge Michel
Published: February 2021

A toroidal plasma compressed by a collapsing flux conserver is analyzed to reveal stable scenarios of operation to high compression ratios. The resistive and ideal MHD stability is calculated in full toroidal geometry, using the asymptotic matching method in realistic conditions, and comparing with nonlinear simulations. The near edge current profile, controlled by toroidal field ramping during compression, is shown to be critical to stability due to coupling between poloidal components of the least stable mode. The extension of a length of shaft on axis is also found to be critical at high compression, as the resulting good curvature region in magnetic field stabilizes pressure driven modes that would otherwise be unstable. This work extends from previous studies, which initially showed the existence of a stable scenario, to include findings of more extensive stable zones, detailed effects of geometry, and nonlinear simulations of the instabilities. The nonlinear simulations of the compression are consistent with the linear analyses, confirming both the conservation and stability properties.
Ion temperature gradient control using reinforcement learning technique
Authors: Wakatsuki T. , Suzuki T. , Oyama N. , Hayashi N.
Published: February 2021

Plasma with an internal transport barrier (ITB) is desirable for a steady-state tokamak reactor because of its high confinement quality and high bootstrap current fraction. However, the local pressure gradient tends to be steep and the plasma often becomes unstable. In this study, an ion temperature gradient control system based on neutral beam injection (NBI) is developed using the reinforcement learning technique. The response characteristics of an ion temperature gradient to NBI are non-linear and sensitive to experimental conditions, which makes it difficult to develop a robust control system. Our control system is trained for plasmas with a wide range of ITB strengths. Using the reinforcement learning technique, the system acquires a robust control feature through several thousand iterations of trial and error in an integrated transport simulation hosted by TOPICS. The control system is composed of neural networks (NNs) whose input variables are the ion temperature gradient, the current NBI power, and the NBI powers for several previous control time steps. The trained system can determine a control output which is suitable for the response characteristics inferred from the input variables. The trained control system is tested in the TOPICS simulation using plasma models based on two experimental plasmas of JT-60U with different ITB strengths. It is shown that the ion temperature gradient can be appropriately controlled for both plasmas, which supports the expectation that this system is applicable to real experiments.
The role of data variability and uncertainty in the probability of mitigating environmental impacts from cement and concrete
Authors: Miller Sabbie A
Published: February 2021

Concrete is the most produced manmade material globally. This widespread production results in significant anthropogenic environmental impacts, the awareness of which has spurred advances in material development to lower these burdens. However, proposed changes are often not assessed in the context of the data variability and uncertainty inherent in the environmental impact quantification methods employed. As such, the probability that any suggested strategy will result in a desired effect is not addressed. This work aims to quantitatively examine data variability, an inherent characteristic of elements in supply chains, and data uncertainty, a function of data quality for the system being modeled, in assessments of greenhouse gas (GHG) and air pollutant emissions from concrete production. Data variability is determined through ranges in requisite input values from the literature; data uncertainty is assessed through application of an established pedigree matrix method. Statistical analysis of the emissions from concrete production incorporating sources of variability and uncertainty are examined through Monte Carlo simulations. Concrete mixtures, representing a feasible structural concrete for use in California infrastructure and three alternative mixtures are assessed, as are three GHG emissions mitigation strategies, namely, a change in thermal energy fuel mix, a change in electricity grid, and use of carbon capture and storage. The distributions of emissions derived through statistical analyses are used to examine the probability of efficacy of these strategies, as well as potential co-benefits on air emissions. Results show each constituent change and each mitigation strategy considered would lead to a reduction in GHG emissions if only mean values are compared; however, the probability of these reductions varies. These findings suggest mitigation efforts may not be as definitive as current assessments suggest. Results indicate the importance of using statistical methods to target desirable mitigation efforts in the environmental impacts from concrete production.
Instantons for rare events in heavy-tailed distributions
Authors: Alqahtani Mnerh , Grafke Tobias
Published: February 2021

Large deviation theory and instanton calculus for stochastic systems are widely used to gain insight into the evolution and probability of rare events. At its core lies the fact that rare events are, under the right circumstances, dominated by their least unlikely realization. Their computation through a saddle-point approximation of the path integral for the corresponding stochastic field theory then reduces an inefficient stochastic sampling problem into a deterministic optimization problem: finding the path of smallest action, the instanton. In the presence of heavy tails, though, standard algorithms to compute the instanton critically fail to converge. The reason for this failure is the divergence of the scaled cumulant generating function (CGF) due to a non-convex large deviation rate function. We propose a solution to this problem by ‘convexifying’ the rate function through a nonlinear reparametrization of the observable, which allows us to compute instantons even in the presence of super-exponential or algebraic tail decay. The approach is generalizable to other situations where the existence of the CGF is required, such as exponential tilting in importance sampling for Monte-Carlo algorithms. We demonstrate the proposed formalism by applying it to rare events in several stochastic systems with heavy tails, including extreme power spikes in fiber optics induced by soliton formation.
Energy Efficiency in The Settlement Texture Through the Use of BIM
Authors: Aydin M A , Oral G K
Published: February 2021

In the emerging new and densely settled areas in Turkey, rapid construction and unplanned urbanization where energy efficiency approach is ignored, cause rapid destruction of natural environment and depletion of energy resources. In terms of economic and environmental aspects, the reduction of energy consumption is a matter of priority in the settlement texture design. The settlement texture is a significant design variable to control energy consumption. The dimensions of the buildings, their spacing (distance between buildings) and the arrangement of buildings with respect to one another are the design parameters which define the settlement texture. This study aims to determine the energy efficient settlement texture design parameters by the using Revit that software of BIM. In this context, the first step of the method of the study is to develop different settlement texture alternatives which benefit from the solar energy. In the second step, annual energy consumption for a selected residential building in the developed alternatives is calculated. Finally, calculated annual energy consumptions are analysed and the appropriate of the settlement texture design parameters in terms of energy efficiency are determined. As a result, this study is focused on determining the appropriate settlement texture in terms of energy efficiency by using BIM in order to take the right decisions in the design stage. According to the results of this limited studies with 48 different settlement textures, SF3-10-EW-0.5 achieved the lowest total energy consumption. However, in order to reach an acceptable general conclusion, similar studies should be analyzed for many alternatives.
Flexible indirect x-ray detector enabled by organic photodiode and CsPbBr3 perovskite quantum dot scintillator
Authors: Xiang Li , Wang Ya , Liu Xiyuan , Huang Xuekai , Xin Zhilong , Xu Yangbing , Liu Chuan , Wang Kai , Chen Jun , Yang Yang , Zhang Shengdong , Zhou Hang
Published: February 2021

X-ray photodetection are frequently used in medical diagnoses industrial inspection and environmental radiation detection. Currently, there is an ongoing effort to develop bendable or flexible x-ray photodetectors (PDs) to meet the demand on light weight and arbitrary shape detection system. Here, a highly bendable indirect x-ray PD is designed by coupling a P3HT:PC61BM organic photodetectors (OPDs) with a flexible perovskite quantum dots (QDs) embedded polymer scintillator. The flexible perovskite QDs scintillator exhibits high radioluminescence with emission peak centers at the 537 nm, which falls in maximum absorption range of poly(3-hexylthiophene) (P3HT). The OPD, with

2
μ

m 

active layer, exhibits low dark currents in the range of tens of nanoampere per square centimeter over a wide reversed biased range. The OPD demonstrates detectable light signal down to

0

.1

μ

W

cm

 

−
2

and low dose detection capability. The coupling of perovskite QDs scintillator and OPD shows a sensitivity of 638 e nGy−1 mm−2

10

.2 

μ

C G

y

−

1

 c

m

−

2

at a dose rate of 1 mGy s−1, which brings the possibilities of realizing highly bendable x-ray PDs.
Pulsed laser deposition of oxide and metallic thin films by means of Nd:YAG laser source operating at its 1st harmonics: recent approaches and advances
Authors: Chaluvadi S K , Mondal D , Bigi C , Knez D , Rajak P , Ciancio R , Fujii J , Panaccione G , Vobornik I , Rossi G , Orgiani P
Published: February 2021

Quantum materials are central for the development of novel functional systems that are often based on interface specific phenomena. Fabricating controlled interfaces between quantum materials requires adopting a flexible growth technique capable to synthesize different materials within a single-run deposition process with high control of structure, stoichiometry, and termination. Among the various available thin film growth technologies, pulsed laser deposition (PLD) allows controlling the growth of diverse materials at the level of single atomic layers. In PLD the atomic species are supplied through an ablation process of a stoichiometric target either in form of polycrystalline powders or of a single crystal. No carrier gases are needed in the deposition process. The ablation process is compatible with a wide range of background pressure. We present results of thin-film growth by PLD obtained by using an Nd:YAG infrared pulsed laser source operating at its first harmonics. With respect to the traditional PLD systems—based on excimer KrF UV-lasers—optimal conditions for the growth of thin films and heterostructures are reached at large target-to-substrate distance. Merits and limitations of this approach for growing oxide and non-oxide thin films are discussed. The merits of an Nd:YAG laser to grow very high-quality thin films suggest the possibility of implementing compact in-situ setups e.g. integrated with analytical instrumentation under ultra-high vacuum conditions.
Very high upper critical fields and enhanced critical current densities in Nb3Sn superconductors based on Nb–Ta–Zr alloys and internal oxidation
Authors: Buta F , Bonura M , Matera D , Bovone G , Ballarino A , Hopkins S C , Bordini B , Chaud X , Senatore C
Published: February 2021

The inhibition of Nb3Sn grain growth in the presence of ZrO2 nanoparticles appears to be one of the most promising method for pushing the critical current densities of Nb3Sn superconducting wires to levels that meet the requirements set for the Future Circular Collider. We have investigated the effect of ZrO2 nanoparticles formed by the internal oxidation of Zr on the superconducting properties and microstructure of Nb3Sn formed from Nb-1 wt%Zr, Nb-7.5 wt%Ta, Nb-7.5 wt%Ta-1 wt%Zr and Nb-7.5 wt%Ta-2 wt%Zr alloys. A monofilamentary wire configuration was used, with a 0.22 mm outer diameter Nb-alloy tube containing a core of powdered metal oxide (SnO2, CuO or MoO3) as oxygen source and successive deposits of Cu, Sn and Cu on the outer surface. As determined from inductive measurements, the layer critical current densities of the samples based on Nb alloys with internally oxidized Zr were superior to those based on Nb-7.5 wt%Ta. The samples based on Nb-7.5 wt%Ta-1 wt%Zr and Nb-7.5 wt%Ta-2 wt%Zr showed higher critical current densities at high magnetic fields (above 10–15 T), and upper critical fields exceeding 28.5 T at 4.2 K (99% normal state resistivity criterion). A record value of 29.2 T of the upper critical field at 4.2 K was obtained on samples based on Nb-7.5 wt%Ta-2 wt%Zr. Hypotheses are proposed and discussed for explaining this unexpected increase of the upper critical field, by considering the possible effects of non-oxidized Zr on the superconducting properties of Nb3Sn and of the oxidized Zr on the formation and microchemistry of Nb3Sn. Regardless of sample type the Nb3Sn grains observed in our samples have an aspect ratio of 1.5–1.7. When compared in the short axis direction, the mean distance between grain boundary intercepts (lineal intercept method) is ∼40% smaller in the samples with internally oxidized Zr than in the reference samples based on Nb-7.5 wt%Ta. In the long axis direction the reduction is of 20%–30%.
An experimental technique to simulate and measure leakages in twin-screw compressor
Authors: Patel Hitesh H , Lakhera Vikas J
Published: February 2021

The phenomenon of leakages through various clearances in the twin-screw compressor and its accurate prediction affect its design and performance. The blowhole leakage within the twin-screw compressor is estimated by previous researchers using the convergent nozzle equation, which has certain idealized assumptions and hence has a scope of improvement considering the actual phenomena taking place within the screw compressor. The mathematical model presented in this study takes into account, the shape of a gap and its geometric dimensions, the parameters before and after the gap, the gas friction and the local resistance at entry and exit. An iterative model is used to calculate the leakage rate through the blowhole cross-sections at different pressure differences. The analytical results for the leakage using the mathematical models are verified experimentally by simulating the leakages through the circular cross section convergent nozzles of different sizes at different pressure differences. The experimental study along with analytical deduction suggests suitable multiplier to estimate the blowhole leakages within ±7.2%. This methodology may be extended to estimate the other types of leakages occurring dynamically within the screw compressor and fluid flow systems.
Conventional and unconventional ionic phenomena in tunable soft materials made of liquid crystals and nanoparticles
Authors: Garbovskiy Yuriy
Published: February 2021

A great variety of tunable multifunctional materials can be produced by combining nanoparticles and liquid crystals. Typically, the tunability of such soft nanocomposites is achieved via external electric fields resulting in the field-induced reorientation of liquid crystals. This reorientation can be altered by ions normally present in liquid crystals in small quantities. In addition, nanomaterials dispersed in liquid crystals can also affect the behavior of ions. Therefore, an understanding of ionic phenomena in liquid crystals doped with nanoparticles is essential for future advances in liquid crystal-aided nanoscience and nanotechnology. This paper provides an overview of the ionic effects observed in liquid crystals doped with nanomaterials. An introduction to liquid crystals is followed by a brief overview of nanomaterials in liquid crystals. After giving a basic description of ions in liquid crystals and experimental methods to measure them, a wide range of ionic phenomena in liquid crystals doped with different types of nanomaterials is discussed. After that, both existing and emerging applications of tunable soft materials made of liquid crystals and nanodopants are presented with an emphasis on the role of ionic effects in such systems. Finally, the discussion of unsolved problems and future research directions completes the review.
Collaborative transition to open access publishing by scholarly societies
Authors: Naim Kamran , Brundy Curtis , Samberg Rachael G.
Published: February 2021

For decades, universities, researchers, and libraries have sought a systemwide transition of scholarly publishing to open access (OA), but progress has been slow. There is now a potential for more rapid and impactful change, as new collaborative OA publishing models have taken shape. Cooperative publishing arrangements represent a viable path forward for society publishers to transition to OA as the default standard for disseminating research. The traditional article processing charge OA model has introduced sometimes unnavigable financial roadblocks, but cooperative arrangements premised on collective action principles can help to secure long-term stability and prevent the risk of free riding. Investment in cooperative arrangements does not require that cash-strapped libraries discover a new influx of money as their collection budgets continue to shrink, but rather that they purposefully redirect traditional subscription funds toward publishing support. These cooperative arrangements will require a two-way demonstration of trust: On one hand, libraries working together to provide assurances of sustained financial support, and on the other, societies’ willingness to experiment with discarding subscriptions. Organizations such as Society Publishers Coalition and Transitioning Society Publications to Open Access are committed to education about and further development of scalable and cooperative OA publishing models.
Neuropsychiatric symptoms in early stage of Alzheimer’s and non-Alzheimer’s dementia, and the risk of progression to severe dementia
Authors: Liew Tau Ming
Published: February 2021

Background

Neuropsychiatric symptoms (NPSs) in early dementia have been suggested to predict a higher risk of dementia progression. However, the literature is not yet clear whether the risk is similar across Alzheimer's dementia (AD) and non-Alzheimer's dementia (non-AD), as well as across different NPSs. This study examined the association between NPSs in early dementia and the risk of progression to severe dementia, specifically in AD and non-AD, as well as across various NPSs.

Method

This cohort study included 7,594 participants who were ≥65 years and had early dementia (global Clinical Dementia Rating [CDR] = 1). Participants completed Neuropsychiatric-Inventory–Questionnaire at baseline and were followed-up almost annually for progression to severe dementia (global CDR = 3) (median follow-up = 3.5 years; interquartile range = 2.1–5.9 years). Cox regression was used to examine progression risk, stratified by AD and non-AD.

Results

The presence of NPSs was associated with risk of progression to severe dementia, but primarily in AD (HR 1.4, 95% confidence interval [CI]: 1.1–1.6) and not in non-AD (HR 0.9, 95% CI: 0.5–1.5). When comparing across various NPSs, seven NPSs in AD were associated with disease progression, and they were depression, anxiety, apathy, delusions, hallucinations, irritability and motor disturbance (HR 1.2–1.6). In contrast, only hallucinations and delusions were associated with disease progression in non-AD (HR 1.7–1.9).

Conclusions

NPSs in early dementia—especially among individuals with AD—can be useful prognostic markers of disease progression. They may inform discussion on advanced care planning and prompt clinical review to incorporate evidence-based interventions that may address disease progression.
Viral Host Range database, an online tool for recording, analyzing and disseminating virus–host interactions
Authors: Lamy-Besnier Quentin , Brancotte Bryan , Ménager Hervé , Debarbieux Laurent
Published: February 2021

Abstrtact

Motivation

Viruses are ubiquitous in the living world, and their ability to infect more than one host defines their host range. However, information about which virus infects which host, and about which host is infected by which virus, is not readily available.

Results

We developed a web-based tool called the Viral Host Range database to record, analyze and disseminate experimental host range data for viruses infecting archaea, bacteria and eukaryotes.

Availability and implementation

The ViralHostRangeDB application is available from https://viralhostrangedb.pasteur.cloud. Its source code is freely available from the Gitlab instance of Institut Pasteur (https://gitlab.pasteur.fr/hub/viralhostrangedb).
Interpoint-ranking sign covariance for the test of independence
Authors: Moon Haeun , Chen Kehui
Published: February 2021

We generalize the sign covariance introduced by Bergsma & Dassios (2014) to multivariate random variables and beyond. The new interpoint-ranking sign covariance is applicable to general types of random objects as long as a meaningful similarity measure can be defined, and it is shown to be zero if and only if the two random variables are independent. The test statistic is a $U$-statistic, whose large-sample behaviour guarantees that the proposed test is consistent against general types of alternatives. Numerical experiments and data analyses demonstrate the superior empirical performance of the proposed method.
Watchful waiting for small non-functional pancreatic neuroendocrine tumours: nationwide prospective cohort study (PANDORA)
Authors: Heidsma C M , Engelsman A F , van Dieren S , Stommel M W J , de Hingh I , Vriens M , Hol L , Festen S , Mekenkamp L , Hoogwater F J H , Daams F , Klümpen H -J , Besselink M G , van Eijck C H , Nieveen van Dijkum E J
Published: February 2021

This prospective nationwide cohort study examined the feasibility of a watchful-waiting protocol for non-functional pancreatic neuroendocrine tumours (NF-pNET) of 2 cm or smaller. In total, 8 of 76 patients (11 per cent) with a NF-pNET no larger than 2 cm showed significant tumour progression (more than 0.5 cm/year) during 17 months of follow-up, of whom two opted for resection. No patient developed metastases. Quality of life was poorer than in the reference population. Watchful waiting seems a safe alternative to upfront surgery in patients with a NF-pNET no larger than 2 cm, although longer follow-up is necessary.
Plasma Metabolomic Profiling of Patients Recovered From Coronavirus Disease 2019 (COVID-19) With Pulmonary Sequelae 3 Months After Discharge
Authors: Xu Juanjuan , Zhou Mei , Luo Ping , Yin Zhengrong , Wang Sufei , Liao Tingting , Yang Fan , Wang Zhen , Yang Dan , Peng Yi , Geng Wei , Li Yunyun , Zhang Hui , Jin Yang
Published: February 2021

Background

Elucidation of the molecular mechanisms involved in the pathogenesis of coronavirus disease 2019 (COVID-19) may help to discover therapeutic targets.

Methods

To determine the metabolomic profile of circulating plasma from COVID-19 survivors with pulmonary sequelae 3 months after discharge, a random, outcome-stratified case-control sample was analyzed. We enrolled 103 recovered COVID-19 patients as well as 27 healthy donors, and performed pulmonary function tests, computerized tomography (CT) scans, laboratory examinations, and liquid chromatography-mass spectrometry.

Results

Plasma metabolite profiles of COVID-19 survivors with abnormal pulmonary function were different from those of healthy donors or subjects with normal pulmonary function. These alterations were associated with disease severity and mainly involved amino acid and glycerophospholipid metabolic pathways. Furthermore, increased levels of triacylglycerols, phosphatidylcholines, prostaglandin E2, arginine, and decreased levels of betain and adenosine were associated with pulmonary CO diffusing capacity and total lung capacity. The global plasma metabolomic profile differed between subjects with abnormal and normal pulmonary function.

Conclusions

Further metabolite-based analysis may help to identify the mechanisms underlying pulmonary dysfunction in COVID-19 survivors, and provide potential therapeutic targets in the future.
Low Immune Activation in Early Pregnancy Is Associated With Preterm But Not Small-for-gestational-age Delivery in Women Infected With Human Immunodeficiency Virus Initiating Antiretroviral Therapy in Pregnancy: A Prematurity Immunology in HIV-infected Mothers and their Infants Study (PIMS) Case-control Study in Cape Town, South Africa
Authors: Mdletshe Nontlantla , Thobakgale Christina , Malaba Thokozile R , Madlala Hlengiwe , Myer Landon , Muema Daniel M , Mogeni Polycarp , Gray Clive M , Altfeld Marcus , Newell Marie-Louise , Ndung’u Thumbi
Published: February 2021

Background

Mechanisms underlying an association between human immunodeficiency virus (HIV) or antiretroviral therapy (ART) during pregnancy with risk of preterm delivery (PTD) and small-for-gestational-age (SGA) remain unclear. We explored the association between cellular immune activation and PTD or SGA in women with HIV initiating ART during or before pregnancy.

Methods

Women with HIV enrolled at median 15 weeks’ gestation, were analyzed for immune markers, and matched on ART initiation timing (15 women initiated pre- and 15 during pregnancy). There were 30 PTD (delivery <37 weeks), 30 SGA (weight for age ≤10th percentile) cases, and 30 controls (term, weight for gestational age >25th percentile) as outcomes. Lymphocytes, monocytes, and dendritic cell populations and their activation status or functionality were enumerated by flow cytometry.

Results

PTD cases initiating ART in pregnancy showed decreased CD8+ T cell, monocyte, and dendritic cell activation; increased classical (CD14+CD16–) and intermediate (CD14+CD16+) monocyte frequencies; and decreased inflammatory monocytes (CD14dimCD16+) compared with SGA cases and term controls (all P < .05). Allowing for baseline viral load, the immune markers remained significantly associated with PTD but only in women initiating ART in pregnancy. Lower monocyte activation was predictive of PTD. TLR ligand-induced interferon-α and macrophage inflammatory protein-1β levels in monocytes were significantly lower in PTD women initiating ART in pregnancy.

Conclusion

Low immune activation, skewing toward anti-inflammatory monocytes, and lower monocyte cytokine production in response to TLR ligand stimulation were associated with PTD but not SGA among women initiating ART in, but not before, pregnancy, suggesting immune anergy to microbial stimulation as a possible underlying mechanism for PTD in women initiating ART in pregnancy.
Characteristics and Factors Associated With Coronavirus Disease 2019 Infection, Hospitalization, and Mortality Across Race and Ethnicity
Authors: Dai Chengzhen L , Kornilov Sergey A , Roper Ryan T , Cohen-Cline Hannah , Jade Kathleen , Smith Brett , Heath James R , Diaz George , Goldman Jason D , Magis Andrew T , Hadlock Jennifer J
Published: February 2021

Background

Data on the characteristics of coronavirus disease 2019 (COVID-19) patients disaggregated by race/ethnicity remains limited. We evaluated the sociodemographic and clinical characteristics of patients across racial/ethnic groups and assessed their associations with COVID-19 outcomes.

Methods

This retrospective cohort study examined 629 953 patients tested for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in a large health system spanning California, Oregon, and Washington between March 1 and December 31, 2020. Sociodemographic and clinical characteristics were obtained from electronic health records. Odds of SARS-CoV-2 infection, COVID-19 hospitalization, and in-hospital death were assessed with multivariate logistic regression.

Results

A total of 570 298 patients with known race/ethnicity were tested for SARS-CoV-2, of whom 27.8% were non-White minorities: 54 645 individuals tested positive, with minorities representing 50.1%. Hispanics represented 34.3% of infections but only 13.4% of tests. Although generally younger than White patients, Hispanics had higher rates of diabetes but fewer other comorbidities. A total of 8536 patients were hospitalized and 1246 died, of whom 56.1% and 54.4% were non-White, respectively. Racial/ethnic distributions of outcomes across the health system tracked with state-level statistics. Increased odds of testing positive and hospitalization were associated with all minority races/ethnicities. Hispanic patients also exhibited increased morbidity, and Hispanic race/ethnicity was associated with in-hospital mortality (odds ratio [OR], 1.39; 95% confidence interval [CI], 1.14–1.70).

Conclusion

Major healthcare disparities were evident, especially among Hispanics who tested positive at a higher rate, required excess hospitalization and mechanical ventilation, and had higher odds of in-hospital mortality despite younger age. Targeted, culturally responsive interventions and equitable vaccine development and distribution are needed to address the increased risk of poorer COVID-19 outcomes among minority populations.
Intravenous to Oral Switch in Complicated Staphylococcus aureus Bacteremia Without Endovascular Infection: A Retrospective Single-Center Cohort Study
Authors: Kouijzer Ilse J E , van Leerdam Eline J , Gompelman Michelle , Tuinte Renee A M , Aarntzen Erik H J G , Berrevoets Marvin A H , Maat Ianthe , Bleeker-Rovers Chantal P , van Crevel Reinout , ten Oever Jaap
Published: February 2021

In this retrospective cohort study, selected patients with disseminated Staphylococcus aureus bacteremia, but without endovascular infection on echocardiography and 18F-FDG-PET/CT, were free of relapse after IV-oral switch. Mortality was low and similar to patients who received prolonged intravenous treatment. IV-oral switch was associated with a shorter length of hospital stay.
Clinical Accuracy and Impact of Plasma Cell-Free DNA Fungal Polymerase Chain Reaction Panel for Noninvasive Diagnosis of Fungal Infection
Authors: Senchyna Fiona , Hogan Catherine A , Murugesan Kanagavel , Moreno Angel , Ho Dora Y , Subramanian Aruna , Schwenk Hayden T , Budvytiene Indre , Costa Helio A , Gombar Saurabh , Banaei Niaz
Published: February 2021

Background

Invasive fungal infection (IFI) is a growing cause of morbidity and mortality in oncology and transplant patients. Diagnosis of IFI is often delayed due to need for invasive biopsy and low sensitivity of conventional diagnostic methods. Fungal cell-free DNA (cfDNA) detection in plasma is a novel testing modality for the noninvasive diagnosis of IFI.

Methods

A novel bioinformatic pipeline was created to interrogate fungal genomes and identify multicopy sequences for cfDNA polymerase chain reaction (PCR) targeting. A real-time PCR panel was developed for 12 genera and species most commonly causing IFI. Sensitivity and specificity of the fungal PCR panel were determined using plasma samples from patients with IFI and non-IFI controls. Clinical impact of the fungal PCR panel was evaluated prospectively based on the treating team’s interpretation of the results.

Results

Overall, the sensitivity and specificity were 56.5% (65/115; 95% confidence interval [CI], 47.4–65.2) and 99.5% (2064/2075; 95% CI, 99.0–99.7), respectively. In the subset of patients with an optimized plasma volume (2 mL), sensitivity was 69.6% (48/69; 95% CI, 57.9–79.2). Sensitivity was 91.7% (11/12; 95% CI, 62.5–100) for detection of Mucorales agents, 56.3% (9/16; 95% CI, 33.2–76.9) for Aspergillus species, and 84.6% (11/13; 95% CI, 56.5–96.9) for Candida albicans. In a prospective evaluation of 226 patients with suspected IFI, cfDNA testing was positive in 47 (20.8%) patients and resulted in a positive impact on clinical management in 20 of 47 (42.6%).

Conclusions

The fungal cfDNA PCR panel offers a noninvasive approach to early diagnosis of IFI, providing actionable results for personalized care.
Short- and long-term mortality after deep sternal wound infection following cardiac surgery: experiences from SWEDEHEART
Authors: Kaspersen Alexander Emil , Nielsen Susanne J , Orrason Andri Wilberg , Petursdottir Astridur , Sigurdsson Martin Ingi , Jeppsson Anders , Gudbjartsson Tomas
Published: February 2021

OBJECTIVES

Deep sternal wound infection (DSWI) is a serious complication after open-heart surgery. We investigated the association between DSWI and short- and long-term all-cause mortality in a large well-defined nationwide population.

METHODS

A retrospective, nationwide cohort study, which included 114676 consecutive patients who underwent coronary artery bypass grafting (CABG) and/or valve surgery from 1997 to 2015 in Sweden. Short- and long-term mortality was compared between DSWI patients and non-DSWI patients using propensity score inverse probability weighting adjustment based on patient characteristics and comorbidities. Median follow-up was 8.0 years (range 0–18.9).

RESULTS

Altogether, 1516 patients (1.3%) developed DSWI, most commonly in patients undergoing combined CABG and valve surgery (2.1%). DSWI patients were older and had more disease burden than non-DSWI patients. The unadjusted cumulative mortality was higher in the DSWI group compared with the non-DSWI group at 90 days (7.9% vs 3.0%, P < 0.001) and at 1 year (12.8% vs 4.5%, P < 0.001). The adjusted absolute difference in risk of death was 2.3% [95% confidence interval (CI): 0.8–3.9] at 90 days and 4.7% (95% CI: 2.6–6.7) at 1 year. DSWI was independently associated with 90-day [adjusted relative risk (aRR) 1.89 (95% CI: 1.38–2.59)], 1-year [aRR 2.13 (95% CI: 1.68–2.71)] and long-term all-cause mortality [adjusted hazard ratio 1.56 (95% CI: 1.30–1.88)].

CONCLUSIONS

Both short- and long-term mortality risks are higher in DSWI patients compared to non-DSWI patients. These results stress the importance of preventing these infections and careful postoperative monitoring of DSWI patients.
Carotid versus femoral access for transcatheter aortic valve replacement: comparable results in the current era
Authors: Marie Basile , David Charles Henri , Guimbretière Guillaume , Foucher Yohann , Buschiazzo Antoine , Letocart Vincent , Manigold Thibaut , Plessis Julien , Jaafar Philippe , Morin Hélène , Rozec Bertrand , Roussel Jean Christian , Sénage Thomas
Published: February 2021

OBJECTIVES

The carotid approach for transcatheter aortic valve replacement (TAVR) has been shown to be feasible and safe. The goal of this study was to compare the 30-day outcomes of trans-carotid (TC) and transfemoral (TF) TAVR.

METHODS

This retrospective study enrolled 500 consecutive patients treated by TC-TAVR (n = 100) or TF-TAVR (n = 400) with percutaneous closure between January 2018 and January 2020 at the Nantes University Hospital. The primary end-point was the occurrence of cardiovascular death and cerebrovascular events at 30 days.

RESULTS

The mean age was 79.9 ± 8.1 in the TC group and 81.3 ± 6.9 (P = 0.069) in the TF group. The TC group had more men (69% vs 50.5%; P = 0.001) and more patients with peripheral vascular disease (86% vs 14.8%; P < 0.0001). Cardiac characteristics were similar between the groups, and the EuroSCORE II was 3.8 ± 2.6% vs 4.6 ± 6.0%, respectively (P = 0.443). The 30-day mortality was 2% in the TC group versus 1% in the TF group (P = 0.345). TC-TAVR was not associated with an increased risk of stroke (2% vs 2.5%; P = 0.999) or major vascular complications (2% vs 4%; P = 0.548). More permanent pacemakers were implanted in the TF group (14.9% vs 5.6%; P = 0.015), and no moderate or severe aortic regurgitation was observed in the TC group (0 vs 3.3%; P = 0.08). TC-TAVR was not associated with an increased risk of mortality or stroke at 30 days (odds ratio 1.32; 95% confidence interval 0.42–4.21; P = 0.63) in the multivariable analysis.

CONCLUSIONS

No statistically significant differences between TC-TAVR and TF-TAVR were observed; therefore, TC-TAVR should be the first alternative in patients with anatomical contraindications to the femoral route.
Beyond alcohol oxidase: the methylotrophic yeast Komagataella phaffii utilizes methanol also with its native alcohol dehydrogenase Adh2
Authors: Zavec Domen , Troyer Christina , Maresch Daniel , Altmann Friedrich , Hann Stephan , Gasser Brigitte , Mattanovich Diethard
Published: February 2021

Methylotrophic yeasts are considered to use alcohol oxidases to assimilate methanol, different to bacteria which employ alcohol dehydrogenases with better energy conservation. The yeast Komagataella phaffii carries two genes coding for alcohol oxidase, AOX1 and AOX2. The deletion of the AOX1 leads to the MutS phenotype and the deletion of AOX1 and AOX2 to the Mut– phenotype. The Mut– phenotype is commonly regarded as unable to utilize methanol. In contrast to the literature, we found that the Mut– strain can consume methanol. This ability was based on the promiscuous activity of alcohol dehydrogenase Adh2, an enzyme ubiquitously found in yeast and normally responsible for ethanol consumption and production. Using 13C labeled methanol as substrate we could show that to the largest part methanol is dissimilated to CO2 and a small part is incorporated into metabolites, the biomass, and the secreted recombinant protein. Overexpression of the ADH2 gene in K. phaffii Mut– increased both the specific methanol uptake rate and recombinant protein production, even though the strain was still unable to grow. These findings imply that thermodynamic and kinetic constraints of the dehydrogenase reaction facilitated the evolution towards alcohol oxidase-based methanol metabolism in yeast.
Performing parentage analysis for polysomic inheritances based on allelic phenotypes
Authors: Huang Kang , Huber Gwendolyn , Ritland Kermit , Dunn Derek W , Li Baoguo
Published: February 2021

Polyploidy poses several problems for parentage analysis. We present a new polysomic inheritance model for parentage analysis based on genotypes or allelic phenotypes to solve these problems. The effects of five factors are simultaneously accommodated in this model: (1) double-reduction, (2) null alleles, (3) negative amplification, (4) genotyping errors and (5) self-fertilization. To solve genotyping ambiguity (unknown allele dosage), we developed a new method to establish the likelihood formulas for allelic phenotype data and to simultaneously include the effects of our five chosen factors. We then evaluated and compared the performance of our new method with three established methods by using both simulated data and empirical data from the cultivated blueberry (Vaccinium corymbosum). We also developed and compared the performance of two additional estimators to estimate the genotyping error rate and the sample rate. We make our new methods freely available in the software package polygene, at http://github.com/huangkang1987/polygene.