bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sample Fetch Rover: Enabling Technologies for Planetary Mobility
Authors: Ridolfi Paolo , Pecover David , Barclay Chris , Allouis Elie , Zekri Eric , Zwick Martin , Azkarate Martin , Poulakis Pantelis , Baglioni Pietro , Carricato Marco 
Published: December 2024

Abstract
The sample fetch rover (SFR) is a novel surface vehicle studied for Mars sample return (MSR). The rover is designed as a multi-mission transportation system with no scientific payloads on board and the only objective of acquiring sample tubes previously deposited on the surface and delivering them to a lander in a strict timeframe. Its mission imposes demanding requirements, such as traverse distance, timeline, mass, volume, and energy, which necessitate the development of new technologies or the augmentation of existing ones. Following the decision not to implement SFR in the MSR campaign, these technologies are becoming attractive for future rover missions to Mars and to the Moon. This paper summarizes the development of these technologies and their applicability to future use cases. The SFR mission profile and design drivers are described herein, along with the system architecture established in response to them. What follows is an overview of the key technologies studied for SFR, focusing on the most critical or innovative ones, such as locomotion, navigation, and sample tube acquisition. The summary includes the other significant aspects of the design: structure, thermal control, mechanisms, control electronics, power, avionics, and communications. For each of these, the main technological advancements and their relevance to forthcoming rover missions are discussed.
Influence of Left Subclavian Artery Stent Graft Geometry on Blood Hemodynamics in Thoracic Endovascular Aortic Repair
Authors: Xue Song , Lu Tiandong , Hu Wenqing , Xia Zeyang , Zhang Jun , Lu Xinwu , Xiong Jing 
Published: December 2024

Abstract
The objective of this research is to analyze the hemodynamic differences in five configurations of left subclavian artery (LSA) stent grafts after LSA endovascular reconstruction in thoracic endovascular aortic repair (TEVAR). For numerical simulation, one three-dimensional thoracic aortic geometry model with an LSA stent graft retrograde curved orientation was reconstructed from post-TEVAR computed tomography angiography (CTA) images, and four potential LSA graft configurations were modified and reconstructed: three straight (0, 2, and 10 mm aortic extension) and one anterograde configuration. The blood perfusion of the LSA, flow field, and hemodynamic wall parameters were analyzed. The vortex evolution process was visualized by the Liutex method which enables accurate extraction of the pure rigid rotational motion of fluid and is highly suitable for identifying the vortex structure of blood flow near the vessel wall. The average flow in the retrograde configuration decreased by 11.2% compared to that in the basic configuration. When the LSA stent graft extends in the aortic lumen, flow separation is observed, and vortex structures begin to form at the proximal inferior arterial geometry and the wall of the extension in late systole. A greater extension length and inflow angle upstream resulted in a greater oscillatory shear index (OSI) and relative residence time (RRT) on the nearby wall of the posterior flow field of the extension. Shorter intra-aortic extension length (&lt;10 mm) and smaller LSA stent graft inflow angle (&lt;120 deg) may be recommended in TEVAR, considering LSA perfusion and minimized flow field disturbance.
Compressor Development for CO2-Based Pumped Thermal Energy Storage Systems
Authors: Held Timothy J. , Miller Jason , Sedlacko Kyle , Cameron Joshua , Morris Scott , Kang Jeongseek , Turner Mark 
Published: December 2024

Abstract
Pumped thermal energy storage (PTES) offers a cost-effective means to store electrical energy for long duration by utilizing a heat pump cycle to transfer thermal energy from a low temperature reservoir (LTR) to a high temperature reservoir (HTR). A key component of the PTES system is the heat pump compressor, which represents a significant driver to the cost, performance, and operating characteristics of the PTES system. At the power rating of the charging process (&gt;100 MW), traditional compressor scaling charts indicate that the operating conditions needed would be best served by a multistage axial compressor. While frame gas turbine compressors at these power ratings exist and operate at higher pressure ratios than needed for the CO2 PTES system, the inlet pressure and fluid density of this application exceeds experience values. The conceptual design of a large-scale CO2 axial compressor was completed, including mean-line estimates of the compressor performance at full power conditions. At steady-state, full power operation, the isentropic efficiency and mechanical efficiency of the compressor have significant impact on the cycle design and round trip efficiency of the PTES system. The results of the conceptual design were used to refine the PTES cycle design, and updated operating conditions provided for further aero design optimization. An important characteristic of the PTES system is its ability to charge at variable rate, which provides significant challenges on compressor operability, especially for a compressor that will be coupled to a fixed-speed synchronous motor. Cycle studies of variable charging rate processes have been conducted, and the impact of compressor operating map characteristics explored. Based on initial modeling studies, single compressor operation can be achieved down to at least 50% of rated power, with further reductions possible depending on the characteristics of the compressor map speedlines.
Experimental Study on Fatigue Performance of TC4 Titanium Alloy Liner Carbon Fiber Composite Cylinders in Seawater Environment
Authors: Yu Yichen , Li Yuanbing , Li Shujing , Dai Yuchen 
Published: December 2024

Abstract
The corrosive nature of seawater poses significant challenges to the design of gas cylinders in marine environments. Currently, TC4 titanium-alloy cylinders are predominantly used because of their resistance; however, they are costly and challenging to manufacture. To address this issue, this study proposes employing TC4 titanium alloy liner carbon fiber composite cylinders, which can reduce the manufacturing cost and processing difficulty while ensuring excellent protection against seawater corrosion and fatigue resistance. The fatigue life of the cylinders was predicted and analyzed using the finite element method, and a prototype was manufactured for verification. The results show that the composite layer can effectively share the stress load for the liner under the working pressure cycle, which increases the fatigue life of the titanium alloy liner carbon fiber composite cylinders and provides strong support for their application in marine engineering.
Reassessment of the Conventional: Numerical Validation of a One-Dimensional Model for the Prediction of Volute Losses
Authors: Ceyrowsky Thomas , Hildebrandt Andre , Heinrich Martin , Schwarze Rüdiger 
Published: December 2024

Abstract
The flow inside the volute of a centrifugal compressor is complex and three-dimensional. The fluid follows a swirling flow pattern, and under many operating conditions, the flow quantities are highly inhomogeneous in radial and circumferential directions. Despite the complex flow physics, the common one-dimensional approach to predict losses inside a volute is simple: The kinetic energy of each velocity component at volute inlet is charged with a loss coefficient. In case of the radial velocity, it is assumed to be constant, while the loss coefficient of the tangential velocity depends on whether the flow inside the scroll is de- or accelerated. In the former case, the loss of a sudden expansion is assumed, while in the latter case, it is presumed to be zero. The loss coefficient of the conical diffuser is also assumed to be equal to that of a sudden expansion. However, considering the complex flow physics inside the volute, it is questionable how valid these assumptions are. In this work, the authors present a comprehensive assessment of these conventional 1D predictions by investigating an extensive database of computational fluid dynamics (CFD) calculations of one volute as a standalone component. The volute has been supplied with different diffuser widths, and the inlet boundary conditions have been selected to allow for separate investigation of the effects of flow angle and flow rate. The aim is to validate the 1D model against the CFD results across the volute's entire operating range. Therefore, the CFD-predicted total pressure losses within the two subcomponents of the volute (the scroll and the conical diffuser) are assigned to the respective velocity components at volute inlet, in analogy to the 1D predictions. The results show that the loss coefficient of the radial velocity varies notably across the volute's loss map, opposing the 1D assumption of a constant loss coefficient. Conversely, the loss coefficient of the tangential velocity inside the scroll agrees well with the CFD results: High matching coefficients (i.e., lower than design flowrates) lead to high loss coefficients, which decrease almost continuously toward low matching coefficients (i.e., higher than design flowrates). The losses inside the conical diffuser depend not only on the matching coefficient but also on the flow angle at volute inlet, contrary to what the 1D model assumes. The fundamental characteristics of the global loss coefficient are predicted satisfactorily by the 1D model, while it generally overpredicts losses. Additionally, the CFD results reveal that the matching coefficient that gives minimum loss coefficients varies with the flow angle, which is not accounted for by the 1D model. Therefore, it is not adequate for assessing volute matching.
Numerical Study on the Effect of Back Cavity on the Aerodynamic Behavior of a Non-Axisymmetric Casing Treatment for Transonic Axial Compressors
Authors: Simon Martin , Benoit Rodriguez 
Published: December 2024

Abstract
For decades, aeronautic engineers have studied the potential of Casing Treatments (CT) to improve the aerodynamic operability of tip-limited compressors. Axial Slot Casing Treatment (or ASCT) has shown very good results on modern transonic compressor. One possible variant of ASCT uses a circumferential back cavity that links the slots outside the compressor main flow path. This study does a back-to-back comparison of two CT designs that differ only by the presence or the absence of the back cavity. The influence of both CT designs on transonic rotor performances and aerodynamics is presented. CT flows are detailed and analyzed. The analysis focuses on fluid exchanges between the CT and the main flow path. This study is based on CFD simulation; CFD results are, at first, confronted with available experimental data and then analyzed. Detailed CT flow analyses show that the presence of the cavity reduces the amplitude of the velocity fluctuations and allows for a more uniform redistribution of the recirculated mass flow. The presence of the back cavity reduces significantly the flow mass transfer between the main flow and the front part of the slots (situated before the rotor leading edge), as a consequence of the action of the transient vortex developing inside. In addition, the synchronization between the rotor blade passage and the extraction cycle, by the rear part of the slots, differs when back cavity is present or not. With the back cavity, the slot tends to extract mass flow mostly when it is close to the pressure side. Without the back cavity, the extraction is performed mostly in the middle of the blade channel. Because of these differences, the back cavity reduces the influence of the CT on rotor efficiency at the cost of a reduction in its capability to improve stall margin.
Efficient
in vitro
assay for evaluating drug efficacy and synergy against emerging SARS-CoV-2 strains
Authors: Woodall Maximillian , Ellis Samuel , Zhang Shengyuan , Kembou-Ringert Japhette , Kite Kerry-Anne , Buggiotti Laura , Jacobs Amy I. , Agyeman Akosua Adom , Masonou Tereza , Palor Machaela , McHugh Timothy D. , Breuer Judith , Standing Joseph F. , Smith Claire M. 
Published: December 2024

ABSTRACT

Novel and repurposed antiviral drugs are available for the treatment of coronavirus disease 2019 (COVID-19). However, antiviral combinations may be more potent and lead to faster viral clearance, but the methods for screening antiviral combinations against respiratory viruses are not well established and labor-intensive. Here, we describe a time-efficient (72–96 h) and simple
in vitro
drug-sensitivity assay for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) using standard 96-well plates. We employ different synergy models (zero interaction potency, highest single agent, Loewe, Bliss) to determine the efficacy of antiviral therapies and synergistic combinations against ancestral and emerging clinical SARS-CoV-2 strains. We found that monotherapy of remdesivir, nirmatrelvir, and active metabolite of molnupiravir (EIDD-1931) demonstrated baseline EC50s within clinically achievable levels of 4.34 mg/L (CI: 3.74–4.94 mg/L), 1.25 mg/L (CI: 1.10–1.45 mg/L), and 0.25 mg/L (CI: 0.20–0.30 mg/L), respectively, against the ancestral SARS-CoV-2 strain. However, their efficacy varied against newer Omicron variants BA.1.1.15 and BA.2, particularly with the protease inhibitor nirmatrelvir. We also found that remdesivir and nirmatrelvir have a consistent, strong synergistic effect (Bliss synergy score >10) at clinically relevant drug concentrations (nirmatrelvir 0.25–1 mg/L with remdesivir 1–4 mg/L) across all SARS-CoV-2 strains tested. This method offers a practical tool that streamlines the identification of effective combination therapies and the detection of antiviral resistance. Our findings support the use of antiviral drug combinations targeting multiple viral components to enhance COVID-19 treatment efficacy, particularly in the context of emerging viral strains.
The phospho-ferrozine assay: a tool to study bacterial redox-active metabolites produced at the plant root
Authors: Giacalone David , Schutt Emilly , McRose Darcy L. 
Published: December 2024

ABSTRACT

Soil microbial communities are pivotal to plant health and nutrient acquisition. It is becoming increasingly clear that many interactions, both among and between microbes and plants, are governed by small bioactive molecules or “secondary metabolites” that can aid in communication, competition, and nutrient uptake. Yet, secondary metabolite biogeography – who makes what, where, and why—is in its infancy. Further, secondary metabolite biosynthesis genes are often silent or weakly expressed under standard laboratory conditions, making it incredibly difficult to study these small molecules. To begin to address these dual challenges, we focused on redox-active metabolites (RAMs), a specific class of small molecules, and took advantage of recent findings that many RAMs aid in acquiring phosphorus and that their production is frequently stimulated by stress for this macronutrient. We developed a screen for RAM-producing bacteria that leverages phosphorus limitation to stimulate metabolite biosynthesis and uses a colorimetric (ferrozine) iron-reduction assay to identify redox activity. We isolated 557 root-associated bacteria from grasses collected at sites across the United States (Santa Rita Experimental Range [AZ], Konza Prairie Biological Station [KS], and Harvard Forest [MA]) and from commercial tomato plants and screened them for RAM production. We identified 128 soil isolates of at least 19 genera across Proteobacteria, Actinobacteria, Firmicutes, and Bacteroidetes that produced RAMs under phosphorus stress. Our work reveals that the production of RAMs under phosphorus stress is common across diverse soil bacteria and provides an approach to screen for these small molecules rapidly.

IMPORTANCE
By secreting secondary metabolites, bacteria at the plant root can defend against diseases and help acquire essential nutrients. However, the genes that synthesize secondary metabolites are typically inactive or are weakly expressed under standard laboratory conditions. This fact makes it difficult to study these small molecules and hinders the discovery of novel small molecules that may play crucial roles in agricultural and biomedical settings. Here, we focus on redox-active metabolites (RAMs), a class of secondary metabolites that can help bacteria solubilize phosphorus and are often produced when phosphorus is limited. We developed a screen that rapidly identifies RAM-producing bacteria by utilizing a colorimetric iron-reduction assay in combination with phosphorus limitation to stimulate biosynthesis. The screen reveals that RAM-producing bacteria are far more prevalent in soil than previously appreciated and that this approach can be used to identify RAM producers.
Overcoming barriers for investigating nickel-pincer nucleotide cofactor-related enzymes
Authors: Nevarez Jorge L. , Turmo Aiko , Gatreddi Santhosh , Gupta Swati , Hu Jian , Hausinger Robert P. 
Published: December 2024

ABSTRACT

The nickel-pincer nucleotide (NPN) cofactor is a modified pyridinium mononucleotide that tri-coordinates nickel and is crucial for the activity of certain racemases and epimerases. LarB, LarC, and LarE are responsible for NPN synthesis, with the cofactor subsequently installed into LarA homologs. Hurdles for investigating the functional properties of such proteins arise from the difficulty of obtaining the active, NPN cofactor-loaded enzymes and in assaying their diverse reactivities. Here, we show that when the
Lactiplantibacillus plantarum lar
genes are cloned into the Duet expression system and cultured in
Escherichia coli
, they confer lactate racemase activity to the cells. By replacing
L. plantarum larA
with related genes from other microorganisms, this system allows for the generation of active LarA homologs. Furthermore, the Duet system enables the functional testing of LarB, LarC, and LarE homologs from other microorganisms. In addition to applying the Duet expression system for synthesis of active, NPN cofactor-containing enzymes in
E. coli
, we demonstrate that circular dichroism spectroscopy provides a broadly applicable means of assaying these enzymes. By selecting a wavelength of high molar ellipticity and low absorbance for a given 2-hydroxy acid substrate enantiomer, the conversion of one enantiomer/epimer into the other can be monitored for LarA homologs without the need for any coupling enzymes or reagents. The methods discussed here further our abilities to investigate the unique activities of Lar proteins.

IMPORTANCE

Enzymes containing the nickel-pincer nucleotide (NPN) cofactor are prevalent in a wide range of microorganisms and catalyze various critical biochemical reactions, yet they remain underexplored due, in part, to limitations in current research methodologies. The two significant advancements described here, the heterologous production of active NPN-cofactor containing enzymes in
Escherichia coli
and the use of a circular dichroism-based assay to monitor enzyme activities, expand our capacity to analyze these enzymes. Such additional detailed characterization will deepen our understanding of the diverse chemistry catalyzed by the NPN cofactor and potentially uncover novel roles for this organometallic species in microbial metabolism.
Preliminary clinical performance of a Cas13a-based lateral flow assay for detecting
Neisseria gonorrhoeae
in urine specimens
Authors: Allan-Blitz Lao-Tzu , Adams Gordon , Sanders Gabriela , Shah Palak , Ramesh Krithik , Jarolimova Jana , Ard Kevin L. , Branda John A. , Klausner Jeffrey D. , Sabeti Pardis C. , Lemieux Jacob E. 
Published: December 2024

ABSTRACT

Nucleic acid amplification testing (NAAT) for
N. gonorrhoeae
is unavailable in resource-limited settings. We previously developed a CRISPR-based lateral flow assay for detecting
N. gonorrhoeae
. We aimed to pair that assay with point-of-care DNA extraction, assess performance in clinical urine specimens, and optimize assay kinetics. We collected urine specimens among men presenting with urethritis enrolling in a clinical trial at the Massachusetts General Hospital Sexual Health Clinic. We assessed the quantified DNA yield of detergent-based extractions with and without heat. We selected one detergent for extracting all specimens, paired with isothermal recombinase polymerase amplification for 90 minutes and lateral flow Cas13a detection, interpreted via pixel intensity analysis. We also trained a smartphone-based machine-learning model on 1,008 images to classify lateral flow results. We used the model to interpret lateral flow results from the clinical specimens. We also tested a modified amplification chemistry with a second forward primer lacking the T7-promoter to accelerate reaction kinetics. Extraction with 0.02% Triton X resulted in an average DNA yield of 2.6 × 10
6
copies/µL (SD ± 6.7 × 10
5
). We treated 40 urine specimens (
n
= 12 positive) with 0.02% Triton X, and using quantified pixel intensity analysis, the Cas13a-based assay correctly classified all specimens (100% agreement; 95% CI 91.2%–100%). The machine-learning model correctly classified 45/45 strips in the validation data set and all 40 lateral flow strips from clinical specimens. Including the second forward primer reduced incubation time to 60 minutes. Using point-of-care DNA extraction, our Cas13a-based lateral flow
N. gonorrhoeae
assay demonstrated promising performance among clinical urine specimens.

IMPORTANCE

Using a CRISPR-based assay we previously developed for
Neisseria gonorrhoeae
detection, we developed new techniques to facilitate point-of-care use. We then demonstrated the promising performance of that assay in clinical specimens. Furthermore, we developed a smartphone-based machine learning application for assisting interpretation of lateral flow strip results. Such an assay has the potential to transform the care of sexually transmitted infections in low-resource settings where diagnostic tests are unavailable. A point-of-care pathogen-specific assay, paired with the connectivity offered by a smartphone application, can also support public health surveillance efforts in such areas.