bluuebunny/crossref_metadata_2025 huggingface dataset:
Opportunities for Integrating Particle-Based Concentrated Solar Power Generation With a Fluidized Desalinating Heat Exchanger: A Technoeconomic Analysis
Authors: Brooks Joshua D.
Published: September 2023

The World is drifting closer to a future of unparalleled water resource management challenges. Rising global population, agriculture production, and energy demand have driven a projected increase in annual global water demand to an estimated 6,000 km3 by 2050, accounting for approximately 11% of the world’s annual renewable water resources 1–5. Accordingly, water stress is expected to double in the next 30 years, leading to disrupted societies, a change in the global landscape, and a clear threat to national security 6–7. On top of this, reliance on traditional carbon-based energy, ∼86% of the global mix in 2018, has helped produce the World’s current climate crisis 8. Failure to decarbonize our continuously increasing energy production will continue to stress humans and critical systems 6.

Water desalination, removing salt from water, and concentrated solar power (CSP) systems offer partial solutions to the world’s water and energy resource issues, respectively. However, seawater desalination is currently too expensive, water and energy inefficient, and carbon intense 9–10. Likewise, CSP systems are currently expensive, suffer in part from solar intermittency, and consume immense amounts of cooling water 11–12. This paper aims to combat the disadvantages of desalination and CSP systems by investigating the opportunity for integrating these. Specifically, a techno-economic analysis it performed to estimate the efficacy of various integration approaches. Among these, the evaluated case study identified the lowest cost system resulting from the integration of a thermal desalination plant which is thermally driven by a CSP plant’s waste heat and is electrically driven by excess power generated by augmenting the design output of the same CSP plant.
Pore-Scale Simulation of a Tubular Solar Absorber Partially Filled With Raschig Ring Porous Medium for Efficiency Enhancement Purposes
Authors: Ebadi Hossein , Cammi Antonio , Fathi Nima , Savoldi Laura
Published: September 2023

This study considers a partial filling of a novel porous insert to ease the burden of the excessive pressure drop and customize the porous structure with the absorbed flux distribution in a tubular solar absorber. This arrangement would suggest an enhanced porous integration with solar absorbers, in which the fraction of porous material with higher thermal contribution is kept, while the side with lower heat contribution is removed to maintain the pressure drop at low levels. To achieve this goal, a numerical investigation was performed on a novel porous medium made of metallic Raschig Rings (RR), with three different filling percentages of 10, 20, and 30% of the tube cross-section. Simulations were conducted using CFD and validated against the experimental data acquired for a 100% RR porous filling in a tubular absorber tested in a solar furnace. Up to an 80% increase in the pressure drop was observed using partial filling instead of a clear tube while the heat transfer performance in terms of Nu was improved up to > 20%. Moreover, studying the fluid behavior in the porous and non-porous regions revealed that the fluid in the porous zone is pushed away from the matrix into the non-porous region, making a complex behavior at this interface. The influences of different filling percentages on the flow behavior at the interface and the consequence cooling effects on the absorber are also addressed.
Co-Gasification of Gypsum and Municipal Solid Waste Components in CO2 Atmosphere
Authors: Mavukwana Athi-Enkosi , Burra Kiran Raj Goud , Sempuga Baraka Celestin , Gupta Ashwani
Published: September 2023

In the United States, only 12% of the 284 million tons of municipal solid waste (MSW) generated per annum is currently processed for energy recovery. The limitations to processing more MSW for energy recovery include concern of pollutants emission from the current facilities, high investment cost, low product and economic value and thus economic competition with landfilling. The landfilling is not sustainable so that a permanent solution is urgently required. In this paper, we examine the synergistic potential of incorporating gypsum wastes from construction and demolition sector into the CO2 assisted gasification of municipal solid waste. The effect of varying proportions of gypsum during the co-gasification of gypsum with MSW mixture and individual components (wood and polyethylene terephthalate (PET)) using CO2 as the gasification agent was investigated. The results showed that an increase in gypsum proportion in MSW affected the syngas yield. The yield was reduced by 35% when gypsum was added at equal mass proportions (1:1) to MSW. Adding gypsum to wood increased the cumulative yield of syngas by 7%, and the optimum syngas yield was achieved at a 5:1 ratio of wood to gypsum. The yield of syngas also reduced with an increase of gypsum addition to PET. However, the syngas quality was improved with gypsum addition as the yields of hydrocarbon were reduced. Gypsum increased the syngas yield by 25% more for wood than that of MSW and 60% more than PET. This suggests that the feedstock components with a charring tendency to have greater yields of syngas with gypsum addition. This is attributed to gypsum reaction with char intermediates in a solid-solid reaction along with the reaction of CO2 + C = CO to produce CO that has a significant impact on the syngas yield compared to the oxidation of volatiles by gypsum.
Investigations of End-Plates of Various Widths on the Performance of an Optimized Airfoil
Authors: Torres Leovigildo , Rahai Hamid
Published: September 2023

Steady numerical simulations of an optimized airfoil [1, 2] with different-sized end plates have been performed to identify the effect of chord-shaped end plates with different widths on its lift and drag forces. The freestream mean velocity was 10 m/sec. and the Reynolds number based on the airfoil chord length was approximately 2.0 × 105. The new end plates have a width of 1.27, 7.62, or 12.7 cm. The results of the airfoil without the end plates have shown increased lift with increasing the angle of attack (AOA) with a peak lift coefficient of 1.9 and the lift-to-drag ratio was 2.8 at 20 degrees AOA. The addition of the end plates respectively increases and decreases the lift and drag forces with 12.7 cm width end-plates being the most impactful, resulting in a nearly 9.1% increase and over 30% decrease in the lift and drag forces respectively as compared with the corresponding results for the baseline model. For the 1.27 cm width end-plates, the average increase and decrease in respectively lift and drag forces were 5.7% and less than 1% and when the 7.62 cm width end-plates were used these values were 8.2% and over 24%. For all models, there were no significant increases in lift force beyond 40 degrees AOA.
Metals Recovery and Syngas Evolution During Co-Gasification of Municipal Solid Waste and Gypsum
Authors: Mavukwana Athi-Enkosi , Burra Kiran Raj Goud , Sempuga Baraka Celestin , Gupta Ashwani
Published: September 2023

Thermodynamic equilibrium analysis is used to investigate the transformation of metals during the co-gasification of municipal solid waste (MSW) and gypsum (CaSO4). Aspen Plus is combined with Thermo-calc to develop a process model that considers the conversion of metals. The effect of air ratio, temperature, and feed mass ratio (MSW to gypsum) on the syngas evolution and mineral transformation behavior is investigated. The results showed that temperatures below 1050°C, air ratio < 0.4, and MSW to CaSO4 feed mass ratio > 2.5 prevented the gypsum sulfur transformation to sulfur dioxide. About 90 wt% of the products were gases comprising 22% CO and 19% H2. At about 900°C the major minerals formed were CaS (alabandite), melilite, anorthite, rankinite, nepheline, and wollastonite. Melilite, a calcium silicate of aluminum and magnesium, dominated over all other silicates. However, at temperatures > 1000°C, these minerals transform into a more stable calcium orthosilicate (CaSiO4) and molten oxysulfide. Above 1200°C all metals in MSW were transformed into molten oxides. The results show that syngas and minerals can be recovered during the co-gasification of MSW and gypsum revealing the synergetic benefits of co-processing two different low-value waste materials.
A Design Study of an Elasto-Hydrodynamic Seal for sCO2 Power Cycle by Using Physics Informed Neural Network
Authors: Rimon Mohammad Towhidul Islam , Hassan Mohammad Fuad , Lyathakula Karthik Reddy , Cesmeci Sevki , Xu Hanping , Tang Jing
Published: September 2023

Supercritical carbon dioxide (SCO2) is a promising alternative working fluid in power cycles. It offers several benefits, including improved efficiencies, lower power costs, lower water usage, and reduced equipment footprint. At the subcomponent level, there is a lack of suitable shaft end seals to minimize the sCO2 leakage in the turbomachinery, which would otherwise penalize the efficiencies by up to 0.65 percent, for example, for a 500 MWe utility-scale power plant when existing sealing technologies are used such as labyrinth seals. For a potential solution, we propose a simple sleeve-like Elasto-Hydrodynamic (EHD) seal concept that provides low leakage, minimum wear, and no stress concentration. In this work, a numerical study has been performed to model the structural deformation of the EHD seal and fluid flow by using Lame’s equation and simplified Reynold’s equation, respectively. However, the analytical solutions for this type of modeling require a set of coupled differential and highly non-linear equations. Conventional approaches for optimizing the solution often end in convergence issues and require selecting specific flow rates. Therefore, the design equations used in this work have been solved by adopting the Physics Informed Neural Network (PINN) to mitigate these issues. Through using PINN analysis, the throttling behavior of the seal was successfully demonstrated. The deformation of the seal was observed to occur at an axial length of approximately 18mm, while a fixed root condition was imposed at 26.5mm. The initial clearance within the seal was 0.2566mm, but it was observed to decrease as the pressure increased within the range of 60MPa to 90MPa.The fluid flow inside the region also decreased from 0.68kg/s to 0.42kg/s at this high-pressure range. The proposed analysis can be used to design EHD seals for specific cases when more comprehensive simulation models are not readily available or are deemed to be costly.
Start-Up Operation Strategy Optimization of the Solar Field for a Parabolic Trough Concentrated Solar Power Plant
Authors: Zhang Shunqi , Tang Haiyu , Liu Ming , Liu Jiping , Yan Junjie
Published: September 2023

Parabolic trough concentrated solar power (PTCSP) undergoes daily start-ups and shut-downs despite integrating thermal energy storage (TES). The PTCSP start-up process reduces its annual electricity production of PTCSP by 10% to 20% and increases its levelized cost of energy. An energetic analysis of a 50 MW PTCSP shows that nearly 30% of start-up energy loss has energy-saving potential by optimizing the system configuration or operational strategy. However, research on reducing the start-up energy consumption of PTCSP does not draw enough attention. Here, the start-up strategy of the receiver was optimized to reduce the start-up energy consumption. The receiver is divided into two sections with different start-up strategies. The start-up strategy of the first section employs the conventional receiver start-up strategy, and the start-up strategy of the other section is modified based on the power block start-up curve, which reduces the receiver temperature of the solar field. The results indicate that the energy and exergy of TES can be improved by 9.4% and 11.4%, respectively, by optimizing the receiver start-up strategy. The annual electricity production can be improved by 171.1 MWh (∼0.1%), and the annual net income is approximately 30000 $ when the feed-in tariff is 16.4 ¢·kWh−1.
Using Simulation and Experiment to Develop a Design Methodology for Self-Shaping Solid Oxide Fuel Cell Multilayer Ceramic Composites
Authors: Hartwell Alexander R. , Elsayed Saifeldeen K. , Qin Zhao , Ahn Jeongmin
Published: September 2023

Traditional ceramic manufacturing techniques offer a limited assortment of achievable 3D geometries. For multilayer ceramic composites, such as solid oxide fuel cells, this is further limited to only planar and tubular forms. While there has been interest in a variety of advanced manufacturing techniques such as 3D printing, a less conventional option has also gained interest. Self-shaping of multilayer ceramic composites utilizing mismatched thermal expansion coefficient driven bilayer shrinkage is an alternative manufacturing strategy which circumvents many issues associated with other techniques. In this process, a tape cast substrate is sprayed with a patterned or uniform film which contracts relative to the substrate while cooling from the peak sintering temperature to room temperature resulting in controlled deformation. Reliably predicting the final 3D geometry for any arbitrary combination of 2D substrate shape and film pattern is nontrivial, and disagreement between the degree of curvature predicted from theory and that observed from experiment complicate the adoption of this manufacturing strategy.

This work looks at several geometries for which these scaling laws have already been developed and applies them to the ceramic system both through experimentation and simulation. By comparing experiment and simulation, we can modify our model to accurately represent the real material behavior. We seek to accommodate this disagreement so that we may accurately apply the above-mentioned scaling laws to efficiently design starting substrate and film.
Investigation of Ammonia as a Fuel for Solid Oxide Fuel Cells
Authors: Wilhelm Cole , Tamaoki Kenta , Nakamura Hisashi , Ahn Jeongmin
Published: September 2023

Decreasing the generation of CO2 from energy production is a key area in energy research and environmental sustainability. Fuel cells represent a solution to reducing CO2 generation through the use of hydrogen fuel to generate electricity. However, the widespread use of hydrogen fueled fuel cells is generally limited by difficulty of hydrogen storage, transportation, and synthesis. One promising option to address these difficulties is the use of ammonia (NH3) in solid oxide fuel cells (SOFCs), which allows for storage of a liquid fuel source, rather than the highly compressed gaseous fuel. Sourcing hydrogen from ammonia rather than from fossil fuel reformation eliminates the possibility of CO2 generation from SOFC usage. Previous work has proven the ability to generate hydrogen from ammonia at high temperatures in a micro flow reactor (MFR) at high equivalence ratio. The current work seeks to apply a similar methodology directly to standard SOFCs for electricity generation. Construction of the planar SOFC includes a nickel-yttria stabilized zirconia (Ni-YSZ) anode, YSZ electrolyte layer, samarium doped ceria (SDC) electrolyte buffer layer, and lanthanum strontium cobalt ferrite-SDC (LSCF-SDC) cathode layer. A model ammonia exhaust based on the MFR exhaust for equivalence ratio of 4 from the previous work is used. A mixture of NH3, H2, and N2 simulates the MFR exhaust and is supplied to the SOFC. N2 is used to account for all MFR exhaust species outside of NH3 and H2. Testing is completed in a tubular furnace in order to maintain a controlled temperature, with oxygen being supplied to the cathode by ambient air. The buffer-layer SOFC showed high performance on pure H2 at 1V OCV and 343mW/cm2 power density. The performance decreases on model exhaust, but maintains 0.9V OCV and 128mW/cm2 power density. This showcases the ability of SOFCs to generate power from a NH3 supply that primarily contains N2.
Novel Dilution Zone Jet Modifiers: an Experimental and Numerical Study of Combustor Temperature Uniformity
Authors: Soliman Ibrahim , Salem Abdel Rahman , Amano Ryoichi
Published: September 2023

This study focuses on improving the temperature uniformity of mixed gases stream within combustor dilution zones. Temperature uniformity enhancement is investigated by using passive cooling via Modifier Nozzle Parts (MNP), and Modifier Diffuser Parts (MDP) that are installed on the dilution holes. Multiple parts diameter-length scenarios are investigated to select the optimum designs for controlling the velocity and pressure of dilution jets. An experimental setup with Reynolds number (Re) ranging between 104,000 and 271,000 is used to simulate dilution gas mixing and to validate Computational Fluid Dynamics (CFD) models. Results show that lower-length MNP designs provide comparable temperature uniformity factor (χ) enhancement without the added pressure drop, which results from higher lengths — reducing the area ratio for the MNP yields lower (χ) enhancement but with a notable increase in pressure drop. The most effective design in terms of benefit to cost is the MNP design with area shrinkage ratio of quarter (1/4) and a length corresponding to half the radius (∼10 mm) of the dilution hole. This design results in χ enhancement of 6% and an added pressure drop of 9%. The MDP designs performed poorly compared to the MNP designs. The k-ε (RNG) model showed good agreement with experimental data and performed well against k-ω (SST) and Reynolds Stress Turbulence (RST) models.
Descriptions of some caligonellid and stigmaeid mites (Acariformes: Raphignathoidea) from Manisa province, Türkiye
Authors: Akyol Mustafa
Published: September 2023

A new species viz. Molothrognathus acus sp. nov., collected from litter and soil under Pinus brutia (Pinaceae), Molothrognathus tauricus Khaustov, 2021 is recorded for the first time in Turkey and the unknown male of Prostigmaeus amplius Doğan et al., 2020, collected from litter and soil under Olea europaea (Oleaceae) in Manisa province, Türkiye, is described and illustrated. A key to the species of Molothrognathus from Türkiye is provided.
Accent rating of vocoded foreign-accented speech by native listeners
Authors: Yang Jing , Sidhu Jaskirat , Totino Gabrielle , McKim Sarah , Xu Li
Published: September 2023

This study examined accent rating of speech samples collected from 12 Mandarin-accented English talkers and two native English talkers. The speech samples were processed with noise- and tone-vocoders at 1, 2, 4, 8, and 16 channels. The accentedness of the vocoded and unprocessed signals was judged by 53 native English listeners on a 9-point scale. The foreign-accented talkers were judged as having a less strong accent in the vocoded conditions than in the unprocessed condition. The native talkers and foreign-accented talkers with varying degrees of accentedness demonstrated different patterns of accent rating changes as a function of the number of channels.
Fast binaural processing but sluggish masker representation reconfiguration
Authors: Eurich Bernhard , Dietz Mathias
Published: September 2023

Perceptual organization of complex acoustic scenes requires fast binaural processing for accurate localization or lateralization based on short single-source-dominated glimpses. This sensitivity also manifests in the ability to detect rapid oscillating interaural time and phase differences as well as interaural correlation. However, binaural processing has also been termed “sluggish” based on experiments that require binaural detection in a masker with an additional binaural cue change in temporal proximity. The present study shows that the temporal integration windows obtained from data on binaural sluggishness cannot account for the detection of rapid binaural oscillations. A model with fast IPD encoding but a slower process of updating the internal representation of the masker IPD statistics accounted for both experiments of the “fast” and the “sluggish” categories.
An
Anaplasma phagocytophilum
T4SS effector, AteA, is essential for tick infection
Authors: Park Jason M. , Genera Brittany M. , Fahy Deirdre , Swallow Kyle T. , Nelson Curtis M. , Oliver Jonathan D. , Shaw Dana K. , Munderloh Ulrike G. , Brayton Kelly A.
Published: September 2023

Pathogens must adapt to disparate environments in permissive host species, a feat that is especially pronounced for vector-borne microbes, which transition between vertebrate hosts and arthropod vectors to complete their lifecycles. Most knowledge about arthropod-vectored bacterial pathogens centers on their life in the mammalian host, where disease occurs. However, disease outbreaks are driven by the arthropod vectors. Adapting to the arthropod is critical for obligate intracellular rickettsial pathogens, as they depend on eukaryotic cells for survival. To manipulate the intracellular environment, these bacteria use type IV secretion systems (T4SS) to deliver effectors into the host cell. To date, few rickettsial T4SS translocated effectors have been identified and have only been examined in the context of mammalian infection. We identified an effector from the tick-borne rickettsial pathogen
Anaplasma phagocytophilum
, HGE1_02492, as critical for survival in tick cells and acquisition by ticks
in vivo
. Conversely, HGE1_02492 was dispensable during mammalian cell culture and murine infection. We show that HGE1_02492 is translocatable in a T4SS-dependent manner to the host cell cytosol. In eukaryotic cells, the HGE1_02492 localized with cortical actin filaments, which is dependent on multiple sub-domains of the protein. HGE1_02492 is the first arthropod-vector specific T4SS translocated effector identified from a rickettsial pathogen. Moreover, the subcellular target of HGE1_02492 suggests that
A. phagocytophilum
is manipulating actin to enable arthropod colonization. Based on these findings, we propose the name AteA for
Anaplasma
(
phagocytophilum
) tick effector A. Altogether, we show that
A. phagocytophilum
uses distinct strategies to cycle between mammals and arthropods.

IMPORTANCE

Ticks are the number one vector of pathogens for livestock worldwide and for humans in the United States. The biology of tick transmission is an understudied area. Understanding this critical interaction could provide opportunities to affect the course of disease spread. In this study, we examined the zoonotic tick-borne agent
Anaplasma phagocytophilum
and identified a secreted protein, AteA, which is expressed in a tick-specific manner. These secreted proteins, termed effectors, are the first proteins to interact with the host environment. AteA is essential for survival in ticks and appears to interact with cortical actin. Most effector proteins are studied in the context of the mammalian host; however, understanding how this unique set of proteins affects tick transmission is critical to developing interventions.
Nectin-3 and shed forms of CSPG4 can serve as epithelial cell receptors for
Clostridioides difficile
TcdB
Authors: Childress Kevin O. , Cencer Caroline S. , Tyska Matthew J. , Lacy D. Borden
Published: September 2023

Clostridioides difficile
is a Gram-positive bacterium that can cause mild to severe diarrhea, inflammation, and colonic tissue damage in animal hosts. Symptoms of the disease can be attributed to the activity of toxin B (TcdB) secreted by
C. difficile
during infection. TcdB can engage multiple host cell surface receptors
in vitro
; however, little is known about where these receptors localize on colonic tissue and how these interactions promote disease. Here, we used immunofluorescence microscopy to first visualize TcdB interactions with two of the reported receptors, CSPG4 and Nectin-3, on cells
in vitro
. In cells expressing both receptors, we found that TcdB preferentially interacts with CSPG4. In moving to host colonic tissue, we observed novel localization of Nectin-3 within the brush border of epithelial cells and CSPG4 localization at epithelial cell junctions. The unexpected junctional CSPG4 signal led us to the hypothesis that the signal could represent a soluble form of the CSPG4 extracellular domain (ECD) being shed from fibroblasts in the underlying stromal layer of the tissue. To test, we set up a co-culture of epithelial cells and fibroblasts separated by transwell inserts. We observed CSPG4-ECD shed into the media of cultured fibroblasts and an accumulation in epithelial cells following co-culture. We also found that soluble CSPG4-ECD present in the conditioned media from fibroblasts can potentiate TcdB-mediated cytopathic responses in epithelial cells lacking CSPG4 expression. Based on these observations, we propose that Nectin-3 can facilitate the binding of TcdB at the epithelial surface and that a soluble form of CSPG4 derived from stromal cells can contribute to TcdB intoxication of epithelial cells
in vivo
.

Importance

Toxin B (TcdB) is a major virulence factor of
Clostridioides difficile
, a Gram-positive pathogen that is a leading cause of hospital-acquired diarrhea. While previous studies have established that TcdB can engage multiple cell surface receptors
in vitro
, little is known about how these interactions promote disease and where these receptors localize on colonic tissue. Here, we used immunofluorescence microscopy to visualize Nectin-3 and CSPG4 on tissue, revealing unexpected localization of both receptors on colonic epithelial cells. We show that Nectin-3, which was previously characterized as an adherens junction protein, is also localized to the brush border of colonocytes. Staining for CSPG4 revealed that it is present along epithelial cell junctions, suggesting that it is shed by fibroblasts along the crypt-surface axis. Collectively, our study provides new insights into how TcdB can gain access to the receptors Nectin-3 and CSPG4 to intoxicate colonic epithelial cells.
Genome sequencing of 15 acid-tolerant yeasts
Authors: Bagley James A. , Pyne Michael E. , Exley Kealan , Kevvai Kaspar , Wang Qingzhao , Whiteway Malcolm , Martin Vincent J. J.
Published: September 2023

We report draft genome sequences for 15 non-conventional Saccharomycotina yeast strains obtained from public culture repositories. Included in our collection are eight strains of
Pichia
with broad tolerance to dicarboxylic acids. The genome sequences of these strains will enable comparative genomics of acid-tolerant phenotypes and strain engineering of non-conventional hosts.
Complete genome sequence of
Candidatus
Mycobacterium wuenschmannii
,
a nontuberculous mycobacterium isolated from a captive population of Amazon milk frogs
Authors: Zeineldin Mohamed , Hicks Jessica , Ward Hilary J. , Wünschmann Arno , Camp Patrick , Farrell David , Lehman Kimberly , Thacker Tyler C. , Cuthbert Elizabeth
Published: September 2023

A slow growing species of nontuberculous mycobacteria (NTM) was isolated from the liver of an Amazon milk frog. The complete genome of this isolate comprises 5,102,433 bp, exhibiting 66.86% GC content, 4,940 protein-coding sequences, 52 predicted RNA genes, and 39 repeat regions.
Whole-genome sequence of
Paenibacillus amylolyticus
strain W018, isolated from
Triticum aestivum
L. seeds, obtained using nanopore sequencing
Authors: Chebotar Vladimir K. , Gancheva Maria S. , Chizhevskaya Elena P. , Keleinikova Oksana V. , Baganova Maria E. , Zaplatkin Alexander N. , Husainov Kharon A.
Published: September 2023

In this study, we performed nanopore sequencing of the genome of
Paenibacillus amylolyticus
strain W018, isolated from the seeds of winter wheat, cv. Bezostaya 100. The genome size is 7.07 Mb, with a GC content of 45.8%, and contains 8,190 genes.
Uracil-DNA glycosylase of murine gammaherpesvirus 68 binds cognate viral replication factors independently of its catalytic residues
Authors: Smith Kyle R. , Paul Somnath , Dong Qiwen , Anannya Orchi , Oldenburg Darby G. , Forrest J. Craig , McBride Kevin M. , Krug Laurie T.
Published: September 2023

Herpesviruses are large double-stranded DNA viruses that encode core replication proteins and accessory factors involved in nucleotide metabolism and DNA repair. Mammalian uracil-DNA glycosylases (UNG) excise deleterious uracil residues from their genomic DNA. Each herpesvirus UNG studied to date has demonstrated conservation of the enzymatic function to excise uracil residues from DNA. We previously reported that a murine gammaherpesvirus (MHV68) with a stop codon in
ORF46
(ORF46.stop) that encodes for vUNG was defective in lytic replication and latency
in vivo
. However, a mutant virus that expressed a catalytically inactive vUNG (ORF46.CM) had no replication defect unless coupled with additional mutations in the catalytic motif of the viral dUTPase (ORF54.CM). The disparate phenotypes observed in the vUNG mutants led us to explore the non-enzymatic properties of vUNG. Immunoprecipitation of vUNG followed by mass spectrometry in MHV68-infected fibroblasts identified a complex comprising the cognate viral DNA polymerase, vPOL, encoded by
ORF9
, and the viral DNA polymerase processivity factor, vPPF, encoded by
ORF59
. MHV68 vUNG co-localized with vPOL and vPPF in subnuclear structures consistent with viral replication compartments. In reciprocal co-immunoprecipitations, the vUNG formed a complex with the vPOL and vPPF upon transfection with either factor alone or in combination. Lastly, we determined that key catalytic residues of vUNG are not required for interactions with vPOL and vPPF upon transfection or in the context of infection. We conclude that the vUNG of MHV68 associates with vPOL and vPPF independently of its catalytic activity.

IMPORTANCE

Gammaherpesviruses encode a uracil-DNA glycosylase (vUNG) that is presumed to excise uracil residues from viral genomes. We previously identified the vUNG enzymatic activity, but not the protein itself, as dispensable for gammaherpesvirus replication
in vivo
. In this study, we report a non-enzymatic role for the viral UNG of a murine gammaherpesvirus in forming a complex with two key components of the viral DNA replication machinery. Understanding the role of the vUNG in this viral DNA replication complex may inform the development of antiviral drugs that combat gammaherpesvirus-associated cancers.
Identification of the alternative sigma factor regulons of
Chlamydia trachomatis
using multiplexed CRISPR interference
Authors: Hatch Nathan D. , Ouellette Scot P.
Published: September 2023

Chlamydia trachomatis
is a developmentally regulated, obligate intracellular bacterium that encodes three sigma factors: σ66, σ54, and σ28. σ66 is the major sigma factor controlling most transcription initiation during early- and mid-cycle development as the infectious elementary body (EB) transitions to the non-infectious reticulate body (RB) that replicates within an inclusion inside the cell. The roles of the minor sigma factors, σ54 and σ28, have not been well characterized to date; however, there are data to suggest each functions in late-stage development and secondary differentiation as RBs transition to EBs. As the process of secondary differentiation itself is poorly characterized, clarifying the function of these alternative sigma factors by identifying the genes regulated by them will further our understanding of chlamydial differentiation. We hypothesize that σ54 and σ28 have non-redundant and essential functions for initiating late gene transcription thus mediating secondary differentiation in
Chlamydia
. Here, we demonstrate the necessity of each minor sigma factor in successfully completing the developmental cycle. We have implemented and validated multiplexed Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) interference techniques, novel to the chlamydial field to examine the effects of knocking down each alternative sigma factor individually and simultaneously. In parallel, we also overexpressed each sigma factor. Altering transcript levels for either or both alternative sigma factors resulted in a severe defect in EB production as compared to controls. Furthermore, RNA sequencing identified differentially expressed genes during alternative sigma factor dysregulation, indicating the putative regulons of each. These data demonstrate that the levels of alternative sigma factors must be carefully regulated to facilitate chlamydial growth and differentiation.

IMPORTANCE

Chlamydia trachomatis
is a significant human pathogen in both developed and developing nations. Due to the organism's unique developmental cycle and intracellular niche, basic research has been slow and arduous. However, recent advances in chlamydial genetics have allowed the field to make significant progress in experimentally interrogating the basic physiology of
Chlamydia
. Broadly speaking, the driving factors of chlamydial development are poorly understood, particularly regarding how the later stages of development are regulated. Here, we employ a novel genetic tool for use in
Chlamydia
while investigating the effects of dysregulating the two alternative sigma factors in the organism that help control transcription initiation. We provide further evidence for both sigma factors' essential roles in late-stage development and their potential regulons, laying the foundation for deeper experimentation to uncover the molecular pathways involved in chlamydial differentiation.
Cell behaviors underlying
Myxococcus xanthus
aggregate dispersal
Authors: Murphy Patrick , Comstock Jessica , Khan Trosporsha , Zhang Jiangguo , Welch Roy , Igoshin Oleg A.
Published: September 2023

The soil bacterium
Myxococcus xanthus
is a model organism with a set of diverse behaviors. These behaviors include the starvation-induced multicellular development program, in which cells move collectively to assemble multicellular aggregates. After initial aggregates have formed, some will disperse, with smaller aggregates having a higher chance of dispersal. Initial aggregation is driven by two changes in cell behavior: cells slow down inside of aggregates and bias their motion by reversing direction less frequently when moving toward aggregates. However, the cell behaviors that drive dispersal are unknown. Here, we use fluorescent microscopy to quantify changes in cell behavior after initial aggregates have formed. We observe that after initial aggregate formation, cells adjust the bias in reversal timings by initiating reversals more rapidly when approaching unstable aggregates. Using agent-based modeling, we then show dispersal is predominantly generated by this change in bias, which is strong enough to overcome slowdown inside aggregates. Notably, the change in reversal bias is correlated with the nearest aggregate size, connecting cellular activity to previously observed correlations between aggregate size and fate. To determine if this connection is consistent across strains, we analyze a second
M. xanthus
strain with reduced levels of dispersal. We find that far fewer cells near smaller aggregates modified their bias. This implies that aggregate dispersal is under genetic control, providing a foundation for further investigations into the role it plays in the life cycle of
M. xanthus
.

Importance

Understanding the processes behind bacterial biofilm formation, maintenance, and dispersal is essential for addressing their effects on health and ecology. Within these multicellular communities, various cues can trigger differentiation into distinct cell types, allowing cells to adapt to their specific local environment. The soil bacterium
Myxococcus xanthus
forms biofilms in response to starvation, marked by cells aggregating into mounds. Some aggregates persist as spore-filled fruiting bodies, while others disperse after initial formation for unknown reasons. Here, we use a combination of cell tracking analysis and computational simulations to identify behaviors at the cellular level that contribute to aggregate dispersal. Our results suggest that cells in aggregates actively determine whether to disperse or persist and undergo a transition to sporulation based on a self-produced cue related to the aggregate size. Identifying these cues is an important step in understanding and potentially manipulating bacterial cell-fate decisions.
Oxygen evolution from extremophilic cyanobacteria confined in hard biocoatings
Authors: Krings Simone , Chen Yuxiu , Keddie Joseph L. , Hingley-Wilson Suzanne
Published: September 2023

Biocoatings, in which viable bacteria are immobilized within a waterborne polymer coating for a wide range of potential applications, have garnered greater interest in recent years. In bioreactors, biocoatings can be ready-to-use alternatives for carbon capture or biofuel production that could be reused multiple times. Here, we have immobilized cyanobacteria in mechanically hard biocoatings, which were deposited from polymer colloids in water (i.e
.,
latex). The biocoatings are formed upon heating to 37°C and fully dried before rehydrating. The viability and oxygen evolution of three cyanobacterial species within the biocoatings were compared.
Synechococcus
sp. PCC 7002 was non-viable inside the biocoatings immediately after drying, whereas
Synechocystis
sp. PCC 6803 survived the coating formation, as shown by an adenosine triphosphate (ATP) assay.
Synechocystis
sp. PCC 6803 consumed oxygen (by cell respiration) for up to 5 days, but was unable to perform photosynthesis, as indicated by a lack of oxygen evolution. However,
Chroococcidiopsis cubana
PCC 7433, a strain of desiccation-resistant extremophilic cyanobacteria, survived and performed photosynthesis and carbon capture within the biocoating, with specific rates of oxygen evolution up to 0.4 g of oxygen/g of biomass per day. Continuous measurements of dissolved oxygen were carried out over a month and showed no sign of decreasing activity. Extremophilic cyanobacteria are viable in a variety of environments, making them ideal candidates for use in biocoatings and other biotechnology.

IMPORTANCE

As water has become a precious resource, there is a growing need for less water-intensive use of microorganisms, while avoiding desiccation stress. Mechanically robust, ready-to-use biocoatings or “living paints” (a type of artificial biofilm consisting of a synthetic matrix containing functional bacteria) represent a novel way to address these issues. Here, we describe the revolutionary, first-ever use of an extremophilic cyanobacterium (
Chroococcidiopsis cubana
PCC 7433) in biocoatings, which were able to produce high levels of oxygen and carbon capture for at least 1 month despite complete desiccation and subsequent rehydration. Beyond culturing viable bacteria with reduced water resources, this pioneering use of extremophiles in biocoatings could be further developed for a variety of applications, including carbon capture, wastewater treatment and biofuel production.
Impacts of biostimulation and bioaugmentation on woodchip bioreactor microbiomes
Authors: Wang Hao , Feyereisen Gary W. , Wang Ping , Rosen Carl , Sadowsky Michael J. , Ishii Satoshi
Published: September 2023

Woodchip bioreactors (WBRs) are used to remove nutrients, especially nitrate, from subsurface drainage. The nitrogen removal efficiency of WBRs, however, is limited by low temperatures and the availability of labile carbon. Bioaugmentation and biostimulation are potential approaches to enhance nitrate removal of WBRs under cold conditions, but their effectiveness is still unclear. Here, we clarified the effects of bioaugmentation and biostimulation on the microbiomes and nitrate removal rates of WBRs. As a bioaugmentation treatment, we inoculated WBR-borne cold-adapted denitrifying bacteria
Cellulomonas cellasea
strain WB94 and
Microvirgula aerodenitrificans
strain BE2.4 into the WBRs located at Willmar, MN, USA. As a biostimulation treatment, acetate was added to the WBRs to promote denitrification. Woodchip samples were collected from multiple locations in each WBR before and after the treatments and used for the microbiome analysis. The 16S rRNA gene amplicon sequencing showed that the microbiomes changed by the treatments and season. The high-throughput quantitative PCR for nitrogen cycle genes revealed a higher abundance of denitrification genes at locations closer to the WBR inlet, suggesting that denitrifiers are unevenly present in WBRs. In addition, a positive relationship was identified between the abundance of
M. aerodenitrificans
strain BE2.4 and those of
norB
and
nosZ
in the WBRs. Based on generalized linear modeling, the abundance of
norB
and
nosZ
was shown to be useful in predicting the nitrate removal rate of WBRs. Taken together, these results suggest that the bioaugmentation and biostimulation treatments can influence denitrifier populations, thereby influencing the nitrate removal of WBRs.

IMPORTANCE

Nitrate pollution is a serious problem in agricultural areas in the U.S. Midwest and other parts of the world. Woodchip bioreactor is a promising technology that uses microbial denitrification to remove nitrate from agricultural subsurface drainage, although the reactor’s nitrate removal performance is limited under cold conditions. This study showed that the inoculation of cold-adapted denitrifiers (i.e., bioaugmentation) and the addition of labile carbon (i.e., biostimulation) can influence the microbial populations and enhance the reactor’s performance under cold conditions. This finding will help establish a strategy to mitigate nitrate pollution.
Microsurgical excision of a ruptured distal lenticulostriate aneurysm in a child
Authors: Kheyreddin Ali , Semenov Denis , Abramyan Arevik
Published: September 2023

Distal lenticulostriate artery aneurysms are rare but potentially fatal conditions, especially in children. Endovascular management is often considered the first-line treatment, but microsurgical excision may be necessary in certain cases. This article presents a case report of a child with a ruptured distal lenticulostriate artery aneurysm that required careful decision making and preparation before microsurgical excision. MR angiography was performed in the planning phase and neuronavigation was used during surgery. The surgery was a success, with the patient suffering minimal postoperative focal deficit, which later turned out to be transient.
Certolizumab-induced liver injury: as assessed for causality by the updated RUCAM
Authors: Shakhashiro Muna , Crasta Rachel , Javed Faiza
Published: September 2023

We report a case of a woman in her 30s with a history of cholecystectomy, hypertension, type 2 diabetes and rheumatoid arthritis on methotrexate and certolizumab who presented with epigastric pain radiating to the right upper quadrant. Laboratory findings revealed significantly elevated liver enzymes consistent with hepatocellular liver injury. The hepatocellular pattern of liver injury, negative autoimmune serologies and improvement on cessation of certolizumab were consistent with drug-induced hepatotoxicity. We used Roussel Uclaf Causality Assessment Method to assess the likelihood of drug-induced liver injury that showed a score of 7, this was in line with a probable causality grading. Although the patient had a history of methotrexate use, the onset of symptoms and transaminitis coincided with the recent initiation of certolizumab, which was the trigger of hepatocellular injury. Liver enzymes also remained normal after the reinitiation of methotrexate on follow-up.
Incorporating early pregnancy mental health screening and management into routine maternal care: experience from the Rajarata Pregnancy Cohort (RaPCo), Sri Lanka
Authors: Agampodi Thilini , Amarasinghe Gayani , Wickramasinghe Anuprabha , Wickramasinghe Nuwan , Warnasekara Janith , Jayasinghe Imasha , Hettiarachchi Ayesh , Nimesha Dilshi , Dilshani Thivanka , Senadheera Subhashinie , Agampodi Suneth
Published: September 2023

Early identification of mental health problems in pregnancy in low-income and middle-income countries is scarcely reported. We present the experience of a programme assimilating screening and management of antenatal anxiety and depression in conjunction with the Rajarata Pregnancy Cohort, in Sri Lanka. We adopted a two-stage screening approach to identify the symptoms and the reasons for anxiety and depression. Pregnant women (n=3074), less than 13 weeks of period of gestation underwent screening with the Edinburgh Postnatal Depression Scale (EPDS). Scores were positive among 23% and 14% of women in the first and second trimesters, respectively. Clinical (telephone) interviews (n=78, response 56.9%) were held for women having high EPDS scores to screen for clinical depression using the ‘mental health GAP’ tool. Targeted interventions including counselling, financial and social support and health education were employed. The procedure was repeated in the second trimester with in-person clinical interviews and inquiry into intentional self-harm. Our findings indicated that (1) the majority of mental health problems in early pregnancy were anxiety related to early pregnancy-associated conditions manageable at the primary healthcare level, (2) coupling mental health screening using psychometric tools with clinical interviews facilitates targeted patient-centred care, (3) the majority of intentional self-harm during pregnancy is not in the routine health surveillance system and (4) promoting women to attend the psychiatry clinic in tertiary care hospital has been difficult. Following the experience, we propose a model for mental health service provision in routine pregnancy care programme starting from early pregnancy.
RAD54B inhibits vascular endothelial senescence via suppression of CHK1/p53/p21 pathway
Authors: Mai Yanqi , Lin Tong , Zhang Lili , Yang Wanqi , Liu Sitong , Wang Minghui , Liu Peiqing , Li Zhuoming , Luo Wenwei
Published: September 2023

RAD54B belongs to the SNF2/SWI2 superfamily, participating in homologous recombination repair. DNA damage is the central driver of aging, but there is no direct evidence of an association between RAD54B and vascular aging. The present study sought to investigate the role and mechanisms of RAD54B in endothelial senescence. In senescent animal models, including spontaneously hypertensive rats, normal aging mice, and D-gal-induced senescent mice, and senescent cell models induced by H2O2, D-gal, and culture, RAD54B was remarkably downregulated. Knockdown of RAD54B increased the expression of p53 and p21, increased the ratio of SA-β-gal-positive cells, and decreased the proportion of EdU-positive cells. Conversely, overexpression of RAD54B reversed the senescent phenotypes stimulated by H2O2 and delayed replicative endothelial senescence. Mechanistically, silencing RAD54B compensatorily increased the expression of RAD51/XRCC4, which remained unchanged in H2O2-induced senescence. RAD54B lacking the SNF2 domain could still reverse the increasing expression of p53/p21 induced by H2O2. RAD54B reduced γH2A.X expression and inhibited the expression and phosphorylation of CHK1. In conclusion, RAD54B exerts a direct protective effect against DNA damage through enhancing homologous recombination repair in endothelial senescence, resulting in inhibition of the downstream CHK1/p53/p21 pathway, suggesting that RAD54B may be a potential therapeutic target for vascular aging-associated diseases.