bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis of flavones via the Stork–Danheiser reaction
Authors: Li Jianfeng , Zhou Ankun , Zhang Wenping , Wang Xiaoting , Li Ning
Published: July 2023

A new method based on the Stork–Danheiser reaction is developed to synthesize flavones. The features include transition metal-free, readily available starting materials and simple operations. It allows rapid generation of flavone analogs.
Organocatalysis in ring opening copolymerization as a means of tailoring molecular weight dispersity and the subsequent impact on physical properties in 4D printable photopolymers
Authors: Merckle David , Weems Andrew Christopher
Published: July 2023

Organocatalysis for ring opening copolymerization was used to tailor molecular weight dispersity as a means of tailoring physical properties in 3D printed polyester thermosets made through thiol–ene crosslinking.
Reviewing thermal conductivity aspects of solar salt energy storage
Authors: Gautam Sanjeev , Verma Monika , Chauhan Rashi , Aghara Sukesh , Goyal Navdeep
Published: July 2023

Reviewing thermal conductivity of solar salts with different nanoparticle additives; exploring experimental and theoretical methods.
Analysis of Noun Phrase Ambiguity in Narratives Reveals Differences in Referential Establishment But Not Cohesion for Older Autistic Children
Authors: Zane Emily , Grossman Ruth B.
Published: July 2023

Purpose:

Stories told by autistic narrators often contain relatively frequent use of ambiguous references. However, it remains unclear whether this ambiguity is driven by ambiguous character establishment (e.g., “Once upon a time, she/the girl…”) and/or ambiguous cohesion (e.g., “Two girls lived in a castle. She/The girl…”). In this study, we directly compared rates of each type of ambiguity within and between narratives told by autistic and non-autistic children, to determine which type of ambiguity is relatively more common in narratives told by autistic children.

Method:

Thirty-three 10- to 17-year-old autistic participants (
n
= 17) and non-autistic peers (
n
= 16), who were not statistically different in age, standardized language scores, and IQ scores (
p
> .8 for all), watched two short animated videos alone and then described the videos' events to two listeners who were openly unfamiliar with the videos. We transcribed video recordings of narratives and coded all referential noun phrases (NPs) as either clear or ambiguous. We further categorized ambiguous NPs as either ineffective introduction or ineffective cohesion.

Results:

Autistic children produced significantly higher rates of ambiguous establishment than non-autistic peers, whereas between-group comparisons' rates of ambiguous cohesion were not statistically significant.

Conclusions:

Older children on the autism spectrum show differences in the way they introduce characters, selecting NP types that are only appropriate when their listener is already familiar with the referent. In contrast, once they have introduced characters, they show cohesive skills that are comparable to those of non-autistic peers. Findings support theories arguing that autistic children show differences in their application of social pragmatic principles (listener/context-specific pragmatic rules), whereas their use of linguistic pragmatics (context-independent rules) is similar to that of non-autistic peers.
Adaptive NN control for nominal backstepping form with periodically time‐varying and nonlinearly parameterized switching functions
Authors: Yang Xiaoli , Li Jing , Ge Shuzhi Sam , Li Xiaobo
Published: July 2023

In this paper, the prescribed tracking performance control problem is addressed for uncertain nonlinear systems with unknown periodically time‐varying parameters and arbitrary switching signal. By utilizing radial basis function neural network and fourier series expansion, an approximator is developed to overcome the difficulty of identifying unknown periodically time‐varying and nonlinearly parameterized functions. To achieve the ideal tracking control performance and eliminate the influence of filtering error, a novel command filter‐based adaptive neural network prescribed tracking performance controller is designed by introducing a filtering compensation mechanism. Differently from the standard Backstepping technique, the proposed control scheme eliminates the “explosion of complexity” problem and relaxes the constraint condition on the reference signal. And then, it is warranted that the closed‐loop system is semi‐globally ultimately uniformly bounded and the tracking error is always limited to the specified region bounded by the performance functions. Three simulation examples are used to demonstrate the feasibility of the developed technique in this paper.
Impact of air pressure variations on electrical vehicle motor insulation
Authors: Wang Peng , Yu Chaofan , Akram Shakeel , Fan Ziyuan , Zhao Wenhuan
Published: July 2023

Variation in air pressure severely affects the insulation of electric vehicle (EV) motors, hence weakening the reliability of EVs for safe operation. Nomex‐polyimide‐Nomex, a typical insulation material for EV motors, was used to investigate the motor insulation performance under different air pressures. The results show that the partial discharge inception voltage is significantly reduced for EV motors operated at lower air pressures, and the probability of partial discharge (PD) occurrence is increased. The macroscopic results reveal that the active area of the PD expands at low pressure, while the non‐corroded ring appears in the centre. Additionally, although the number and amplitude of the PD increase significantly with decrease in air pressure, the active area of the PD expands and electrical stress on the insulation per unit area increases slowly. Therefore, when the pressure decreased from 60 to 40 kPa, the endurance life does not show a significant downward trend. Furthermore, the dielectric constant and loss of the low‐pressure samples significantly change during the ageing process, which further indicates critical degradation of the insulation. The aforementioned investigations reveal that the air pressure at different altitudes has a significant impact on the performance of insulation materials.
Effects of gender and degree of formality on the use of euphemistic strategies in Iraqi Arabic
Authors: Mohammed Dawood Milad , Alghazo Sharif , Jarrah Marwan
Published: July 2023

Although euphemism has been studied in many Arabic dialects, it has not yet received due attention in Iraqi Arabic (IA). This study investigates the use of euphemistic strategies by IA speakers and the effect of gender and degree of formality on the use of these strategies. In order to achieve these objectives, a discourse completion test (DCT) was developed and distributed to 160 (80 males and 80 females) Iraqi university students. The data were analysed quantitively and qualitatively using strategies adopted from a number of previous frameworks. The findings show that the participants used a variety of euphemistic strategies, with the deletion strategy being the most frequently used when talking about the topic of death, the fuzzy words strategy for the topic of mental illness, and the implication strategy for the topic of obesity. The analysis also revealed that the degree of formality plays a key role in the use of euphemistic strategies in the topic of mental illness and that gender plays an effective role in the use of euphemistic strategies in all three topics.
Ion pair and larger ion cluster formation in water interfacial regions: An atomic force microscopy study
Authors: Teschke Omar , Soares David Mendez
Published: July 2023

Interfacial regions attached to hydrophobic and hydrophilic surfaces have very low relative permittivities (ε ∼ 3–5), and these low values induce the formation of ion pairs. A detailed description of ion pairing will be possible only after the development of adequate experimental probing methods. The scheme described in this work detects the ion pair (or multistage ion association) formation in water solutions in the interfacial region. Forces acting on the tip when immersed in the interfacial region attached to hydrophilic substrates, such as mica where ε < 7, are attractive (AFM tip dielectric constant = 7). These attractive force steps with extensions equal or smaller than the Bjerrum length at hydrophilic substrates are associated with ion pair formation in interfacial regions. Measurements show that the interfacial water molecular arrangement and ion pairs form an ordered structure (ε < 7) induced by mica interfacial charges. The interfacial region attached to hydrophobic substrates, however, form separated arrangements of ion pairs and water molecular structures as observed by the repulsive steps (ε > 7) intercalated in between attractive regions (ε < 7).
The simulation study of broadband quasi-phase-matching second harmonic generation based on orientation-patterned gallium phosphide and gallium antimonide
Authors: Hu Ruilin , He Qiang
Published: July 2023

Orientation-patterned gallium phosphide (OP-GaP) and orientation-patterned gallium antimonide (OP-GaSb) have demonstrated excellent potential for broadband second harmonic generation (SHG), with a wide range of fundamental wavelengths and temperature tunability, making them promising candidates for use in various applications. In this paper, an analytical demonstration of forward and backward broadband SHG is presented, delivering the fundamental wavelengths in 0.7–12.5 and 2.4–9.8 µm, respectively, through the utilization of OP-GaP and OP-GaSb with quasi-phase-matching (QPM). The temperature tuning ranges for OP-GaP and OP-GaSb are −195–176 and −192–126 °C, respectively. OP-GaP and OP-GaSb can obtain forward broadband QPM SHG when the conditions of QPM and group-velocity matching (GVM) are satisfied simultaneously. The bandwidths of OP-GaP and OP-GaSb with lengths of 10 mm are found to be 776 and 484 nm, respectively, in the forward GVM fundamental wavelength for forward broadband SHG at 25 °C. The bandwidths for backward broadband SHG in the forward GVM fundamental wavelength are also calculated, but the results showed that OP-GaP and OP-GaSb can only achieve forward broadband QPM SHG. Variations of the GVM fundamental wavelength have also been demonstrated as a function of temperature.
Tellurium nanosheets with structural anisotropy formed from defective MoTe2 multilayers
Authors: Muranaka Shuto , Nogamida Satoshi , Hara Kosuke O. , Sawano Kentarou , Hoshi Yusuke
Published: July 2023

We report on the formation of a tellurium nanosheet with a MoOx cap by thermal annealing of ion-implanted 2H–MoTe2 multilayers. The presence of crystal defects generated by ion implantation at an energy of 90 keV accelerates the incorporation of O atoms and the surface desorption of Te atoms in the defective MoTe2 during thermal annealing, and subsequently, a tellurium nanosheet is formed around the bottom regions in the defective MoTe2 due to tellurium segregation. For the angle-resolved Raman spectroscopy, polar plots exhibit two-fold and four-fold symmetries for peak intensities of 121 and 143 cm−1, respectively, signifying the structural anisotropy of the tellurium nanosheet. On reducing the ion energy, the two Raman peak intensities collected from the tellurium nanosheet remarkably decrease, and they disappear for the sample at 30 keV. On the other hand, the decrease of the implantation energy increases the E2g peak intensity at 235 cm−1, which corresponds to the in-plane vibration mode of 2H–MoTe2. The distribution of crystal defects along the depth direction tuned by ion implantation energy is very critical for the formation of a tellurium nanosheet with structural anisotropy from the 2H–MoTe2 multilayers.
The volume erosion rate of the slip cast monolithic and composite ceramics
Authors: Ćurković Lidija , Landek Darko , Švagelj Zrinka , Gabelica Ivana
Published: July 2023

The volume erosion rate of the slip cast monolithic and composite ceramics was studied using SiO2 and SiC particles as erodents, under different impact angles (30°, 60°, 90°), at room temperature. Therefore, three groups of samples were prepared: (i) monolithic alumina (Al2O3); (ii) composite alumina–zirconia (Al2O3–ZrO2) containing 99 wt-% Al2O3 and 1 wt-% ZrO2 and (iii) composite alumina–zirconia (Al2O3–ZrO2) containing 90 wt-% Al2O3 and 10 wt-% ZrO2. Erosion mechanisms of all prepared ceramic samples were evaluated by the volume erosion rate ([Formula: see text], mm3·g–1). Obtained results were compared with the analytical Wiederhorn and Evans equations. The mechanical properties (hardness and fracture toughness) of prepared ceramic samples were compared with their [Formula: see text] under the above-mentioned conditions. It was found that the erosion of monolithic and composite ceramics increased with the increase of the impact angle. Volume erosion rate was highest at an impact angle of 90° and amounts to 115 mm3·g–1 with SiC, and 12 mm3·g–1 with SiO2 erodent particles for monolithic alumina ceramics, 77 mm3·g–1 with SiC, and 8 mm3·g–1 with SiO2 erodent particles for ceramics with the addition of 1 wt-% of ZrO2, and 61 mm3·g–1 with SiC, and 7 mm3·g–1 with SiO2 erodent particles for ceramics with the addition of 10 wt-% of ZrO2. Therefore, it can be concluded that the erosion resistance of monolithic Al2O3 increases with the increasing amount of ZrO2 in the composite Al2O3-ZrO2 ceramics, thus erosion resistance can be improved with the addition of ZrO2.
Estimating the properties of single positive air streamers from measurable parameters
Authors: Bouwman Dennis , Francisco Hani , Ebert Ute
Published: July 2023

We develop an axial model for single steadily propagating positive streamers in air. It uses observable parameters to estimate quantities that are difficult to measure. More specifically, for given velocity, radius, length and applied background field, our model approximates the ionization density, the maximal electric field, the channel electric field, and the width of the charge layer. These parameters determine the primary excitations of molecules and the internal currents. Our approach is to first analytically approximate electron dynamics and electric fields in different regions of a uniformly-translating streamer head, then we match the solutions on the boundaries of the different regions to model the streamer as a whole, and we use conservation laws to determine unknown quantities. We find good agreement with numerical simulations for a range of streamer lengths and background electric fields, even if they do not propagate in a steady manner. Therefore quantities that are difficult to access experimentally can be estimated from more easily measurable quantities and our approximations. The theoretical approximations also form a stepping stone towards efficient axial multi-streamer models.
Solving local constraint condition problem in slave particle theory with the BRST quantization
Authors: Luo Xi , Liu Jianqiao , Yu Yue
Published: July 2023

With the Becchi–Rouet–Stora–Tyutin (BRST) quantization of gauge theory, we solve the long-standing difficult problem of the local constraint conditions, i.e. the single occupation of a slave particle per site, in the slave particle theory. This difficulty is actually caused by inconsistently dealing with the local Lagrange multiplier λ

i
which ensures the constraint: in the Hamiltonian formalism of the theory, λ

i
is time-independent and commutes with the Hamiltonian while in the Lagrangian formalism, λ

i
(t) becomes time-dependent and plays a role of gauge field. This implies that the redundant degrees of freedom of λ

i
(t) are introduced and must be removed by the additional constraint, the gauge fixing condition (GFC) ∂
t

λ

i
(t) = 0. In literature, this GFC was missed. We add this GFC and use the BRST quantization of gauge theory for Dirac’s first-class constraints in the slave particle theory. This GFC endows λ

i
(t) with dynamics and leads to important physical results. As an example, we study the Hubbard model at half-filling and find that the spinon is gapped in the weak U and the system is indeed a conventional metal, which resolves the paradox that the weak coupling state is a superconductor in the previous slave boson mean field (MF) theory. For the t–J model, we find that the dynamic effect of λ

i
(t) substantially suppresses the d-wave pairing gap and then the superconducting critical temperature may be lowered at least a factor of one-fifth of the MF value which is of the order of 1000 K. The renormalized T

c
is then close to that in cuprates.
Compared discharge characteristics and film modifications of atmospheric pressure plasma jets with two different electrode geometries
Authors: Chen 陈 Xiong 雄 , Wang 王 Xing-Quan 兴权 , Zhang 张 Bin-Xiang 彬祥 , Yuan 袁 Ming 明 , Yang 杨 Si-Ze 思泽
Published: July 2023

Atmospheric pressure plasma jet shows great potential for polymer film processing. The electrode geometry is the key factor to determine discharge characteristics and film modification of jets. In this paper, we compared the discharge characteristics and the film modifications of atmospheric pressure plasma jets with needle-ring electrode (NRE) and double-ring electrode (DRE). The results show that jet with NRE has stronger electric field intensity and higher discharge power, making it present more reactive oxygen particles and higher electron temperature, but its discharge stability is insufficient. In contrast, the jet with DRE has uniform electric field distribution of lower field intensity, which allows it to maintain stable discharge over a wide range of applied voltages. Besides, the modification results show that the treatment efficiency of PET film by NRE is higher than that by DRE. These results provide a suitable atmospheric pressure plasma jets device selection scheme for polymer film processing process.
Comparative Study on the Compression Sintering Performance of Different Kinds of Copper-Chromium Powder Applied to Electrical Contact Materials
Authors: Pan Xu , Zhang Jingguo , Ke Xin , Xie Bingqing , Wang Jianwei , Wang Zhong , Wang Limin , Li Zhanrong
Published: July 2023

In this paper, the pressing and sintering properties of three kinds of copper-coated chromium composite powder and copper-chromium mechanical mixed powder with the same copper content were compared and studied. The copper-coated chromium composite powder was prepared by a diffusion sintering method, a liquid electroless plating method, and a diffusion sintering method with an added binder. The results show that with the increase in copper content, the pressing advantage of copper-clad chromium powder is more obvious. The density, hardness, and size shrinkage of the sintered sample are more stable. Moreover, the uniform distribution of Cu and Cr in the copper-coated chromium powder sintered sample can effectively improve the composition uniformity of Cu Cr electrical contact alloy.
Study on Performance Evaluation of Multifunctional Microgel System
Authors: Ye Yinzhu , Liu Yang , Guan Baoshan , Tian Yongda , Shao Liming , Yu Zhentao , Zeng Zhihui , Li Shichao
Published: July 2023

Soft Microgel (SMG) used to enhance oilfield recovery is a kind of aqueous dispersion chemical agent system of microgel particles. It is usually used in medium and low permeability reservoirs and is generally not used for plugging large pores of reservoirs due to the limitation of particle size. To resolve the problem that SMG cannot effectively block large pores of the reservoir, the multi-functional system (SMG-w) can be synthesized by introducing inorganic components into SMG under special conditions. The main physical and chemical properties of SMG-w are carried out in the laboratory. The results of the study show that SMG-w has an excellent resistant ability to temperature and salinity. Besides, it can also decrease the interfacial tension of oil and water. What’s more, it can react with Ca2+ or Mg2+ in formation water from a large number of flocs in the high salinity reservoir, which can enhance physical and chemical properties of SMG-w and make it be applied in deep profile control of high permeability reservoirs with high temperature and high salinity.
A review of thermoresponsive drug delivery systems based on LCST/UCST polymer nanofibers
Authors: Shu Xin
Published: July 2023

Drug delivery systems and thermoresponsive polymers are garnering more interest due to technological advancement. The synthesis, characteristics, and uses of stimuli-responsive polymers in drug delivery systems are discussed in this paper. LCST and UCST polymers, two subtypes of thermoresponsive polymers, are also discussed, along with their processes and biomedical applications. The paper also discusses the use of conventional nanofibers and stimuli-responsive nanofibers for drug delivery systems and the most recent developments in electrospinning technology. The article also analyses the difficulties facing drug delivery systems today. This paper makes the case that novel electrospinning technologies must be developed in addition to further research into drug delivery systems based on UCST polymers with strong biocompatibility and biodegradability.
Study on Efficient Determination of the Content of Key Elements in Thin Stainless Steel by Spark Discharge Optical Emission Spectrometry with Contrivable Sample Thickening
Authors: Yuan Meng , Zhong Fengping , Huang Liuyi , Jin Shuo , Peng Chao , Volodymyr Korzhyk
Published: July 2023

Spark discharge optical emission spectrometry is one of the most effective methods to accurately determine the chemical composition of stainless steel and other metal materials. However, when the thickness of the sample to be tested is less than 3 mm, the test stability of this method decreases and the sample is at risk of breakdown. In this paper, we studied the surface morphology of the excited samples by optical microscope and scanning electron microscope, and analyzed the reasons that affected the testing instability of thin samples. An auxiliary thickening device was proposed to improve the excitation stability of this method, and we realized the efficient determination of key chemical components in thin stainless steel samples. Accurate and stable test results were obtained for 304 stainless steel thin samples with different thicknesses of 1 to 3 mm.
Study on preparation and application of NaCl-KCl-CsCl-Cs2ZrCl6 composite electrolyte
Authors: Zou Wenzhen , Wu Yanke , Wang Lijun
Published: July 2023

Preparing zirconium chloride composite salts such as Cs2ZrCl6 can replace highly volatile ZrCl4 for studying molten salt electrolytic refining zirconium. The NaCl-KCl-CsCl-Cs2ZrCl6 composite electrolyte was prepared using ternary molten salt with a molar ratio of NaCl: KCl: CsCl=30: 24.5: 45.5 and ZrCl4 as raw materials. According to thermodynamic analysis, ZrCl4 preferentially reacts with CsCl to form Cs2ZrCl6 with strong stability. X-ray diffraction analysis showed that the main phase of the product was Cs2ZrCl6. ICP-DSC analysis showed that the conversion rate of ZrCl4 to Cs2ZrCl6 reached 99.68%. To verify the properties of this electrolyte, it is applied to molten salt electrolytic refining sponge zirconium. Studies have shown that this electrolyte system obtains dendrite zirconium products with a maximum grain size of 6.29mm, a system with more application prospects.
Insight into the Effects of Pd Single-atom Particles in the Activation of the Carbon-Chloride Bond
Authors: Huang Jinghan , Liu Rui
Published: July 2023

Palladium (Pd) shows high activity in a variety of catalysis reactions that refer to the activation of the carbon-halogenation bond, and single-atom Pd catalysts have received significant attention as new technology. Nevertheless, there is a huge knowledge gap regarding which Pd sites could form highly reactive centers. It is unclear whether single-atom Pd sites are active in this process or not. In this study, we synthesized Pd/TiO2 nanosheets with Pd loadings of 1%, 5%, and 10% and designed single atom Pd sites and Pd nanoparticles on similar substrates. A scanning transmission electron microscope was used to characterize the synthesized Pd catalysts. As a catalyst, Pd/TiO2 featuring Pd NPs showed high activity in activating the carbon-halogen bond in the activation of carbon-chloride bond, whereas Pd/TiO2 with single Pd atoms showed very low activity in this pros. Accordingly, our results demonstrate that the activation of carbon-halogen bonds cannot be catalyzed by the single-atom Pd sites and emphasize the significance of the ensemble effect in determining the activity of Pd sites.
Study on Enhanced Magnetostriction in (x)PbZr0.52Ti0.48O3-(1-x)NiFe2O4 Composites by Magnetoelectric Effect
Authors: Lu Jiongchen , Shi Zhenhua
Published: July 2023

Magnetoelectric composites (x)PbZr0.52Ti0.48O3(PZT)-(1-x)NiFe2O4 (NFO) with x values of 0.15, 0.30, 0.45, 0.55, 0.75, and 0.85 mol% were obtained by traditional solid phase reaction. The measured magnetic and magnetostriction properties are strongly dependent upon the molar fraction (1-x) of the NFO in the composites. The maximum magnetostriction coefficient of -52.4 ppm was observed in 0.3PZT-0.7NFO composite ceramic. All the magnetostriction in the composites is larger than the reported values. The larger magnetostriction would result from the magnetoelectric (ME) effect of the composites. We propose a model of the magnetostriction within the composites consisting of strain and polarization. The relationship between the ME effect and magnetostriction is discussed in the qualitative features of this model. This magnetoelectric composite material maintains a strong magnetostrictive effect, which can be used in multifunctional sensors. It will provide new ideas for the design of multifunctional sensors in the future.
Study on Preparation and Application of Banana Fiber-Based Composites
Authors: Fan Yuxin
Published: July 2023

Banana fiber is a natural fiber that has gained popularity as an eco-friendly product because it is practical, long-lasting, and biodegradable. The primary source of banana fiber is the stalk, which is an agricultural waste that is typically discarded in a careless way that harms the environment. As a result, a major topic today is how to properly utilize the value of banana fiber and turn it into a treasure. In this exploration, experts have accumulated new information on the examination and utilization of banana fiber. The paper focuses on different composites based on banana fiber, including hybrid fiber composites, thermosetting resin composites, and reinforced thermoplastic polymer composites, which can be synthesized by blending and compounding techniques and exhibit high elasticity, good tensile strength, and good impact resistance. Based on this, banana fiber composites can be used in applications, such as home textiles and household products, where they have good water absorption and abrasion resistance.
Relationship Between Essential Hypertension and Single Nucleotide Polymorphism of Apolipoprotein E Gene in Han, Miao, and Buyi Populations in Guizhou
Authors: Li Ruichao , Song Juhui , Zhao Ansu , Diao Xiaoyan , Zhang Ting , Guan Zhizhong , Wang Chanjuan , He Yan
Published: July 2023

Background

To investigate the correlation between single nucleotide polymorphism (SNP) of human Apolipoprotein E (ApoE) gene and essential hypertension (EH) in Han, Miao, and Buyi populations in Guizhou.

Methods

A case–control study was conducted. A total of 343 patients with EH and 335 healthy controls were selected from Leishan Miao, Libo Buyi, and Guiyang Han populations in Guizhou. The clinical data and biochemical indicators including age, gender, height, weight, fasting blood glucose, cholesterol, and triglyceride were collected. The t test or chi-square test was used to compare the differences of clinical data and biochemical indexes between the 2 groups. Sequenom MassARRAY was used to detect genotype of 5 SNP (rs7259620, rs440446, rs769449, rs1065853, and rs439401) and kompetitive allele-specific PCR (KASP) was used to detect 2 SNP (rs429358 and rs7412) of ApoE gene. Logistic regression was used to analyze the genetic relationship between ApoE gene polymorphisms and EH in Guizhou populations.

Results

Age, overweight, and obesity were independent risk factors for EH in Guizhou populations. Fasting blood glucose and triacylglycerol are independent risk factors for EH in Guizhou Han population. In the Miao and Buyi populations in Guizhou, the correlation between EH and the studied SNP was not statistically significant. In the Han population, the distribution of rs439401 allele and genotype between EH group and control group was significantly different (χ2 = 6.438, P = 0.011; χ2 = 6.389, P = 0.041). Compared with the TT or TC genotype, the genotype CC increased the risk of EH (OR = 2.164, 95% CI 1.035–4.526, P = 0.040). Compared with haplotype G-G-T (rs7259620–rs1065853–rs439401), haplotype G-G-C reduced the risk of EH in Han population (OR = 0.465, 95% CI 0.263–0.824, P = 0.008). Multifactor dimensionality reduction analysis results showed that rs440446, rs429358, and rs7412 had an interaction effect on the occurrence of EH in Miao population (χ2 = 10.012, P = 0.002); rs7259620, rs1065853, and rs439401 had an interaction effect on the occurrence of EH in Buyi population (χ2 = 3.972, P = 0.046); rs7259620, rs440446, and rs439401 had an interaction effect on the occurrence of EH in Han population (χ2 = 10.155, P = 0.001).

Conclusions

The rs439401 of ApoE gene and the haplotype GGC (rs7259620–rs1065853–rs439401) may be associated with the occurrence of EH in Guizhou Han population.
Cytocipher determines significantly different populations of cells in single-cell RNA-seq data
Authors: Balderson Brad , Piper Michael , Thor Stefan , Bodén Mikael
Published: July 2023

Motivation

Identification of cell types using single-cell RNA-seq is revolutionizing the study of multicellular organisms. However, typical single-cell RNA-seq analysis often involves post hoc manual curation to ensure clusters are transcriptionally distinct, which is time-consuming, error-prone, and irreproducible.

Results

To overcome these obstacles, we developed Cytocipher, a bioinformatics method and scverse compatible software package that statistically determines significant clusters. Application of Cytocipher to normal tissue, development, disease, and large-scale atlas data reveals the broad applicability and power of Cytocipher to generate biological insights in numerous contexts. This included the identification of cell types not previously described in the datasets analysed, such as CD8+ T cell subtypes in human peripheral blood mononuclear cells; cell lineage intermediate states during mouse pancreas development; and subpopulations of luminal epithelial cells over-represented in prostate cancer. Cytocipher also scales to large datasets with high-test performance, as shown by application to the Tabula Sapiens Atlas representing >480 000 cells. Cytocipher is a novel and generalizable method that statistically determines transcriptionally distinct and programmatically reproducible clusters from single-cell data.

Availability and implementation

The software version used for this manuscript has been deposited on Zenodo (https://doi.org/10.5281/zenodo.8089546), and is also available via github (https://github.com/BradBalderson/Cytocipher).
Energy budgets of captive Chinese pangolins (Manis pentadactyla)
Authors: Yan Hongmei , An Fuyu , Liu Quansheng , Chi Qingsheng , Wang Kai , Xu Xuelin , Kuang Yingjie , Zhang Zhidong , Hua Yan
Published: July 2023

The Chinese pangolin is an endangered species, and ex situ conservation and captive rescue are important conservation measures. This requires reliable information on nutritional energy requirements and expenditure characteristics. However, we lack sufficient knowledge of their energy physiology to determine their energy requirements for maintenance and growth. An open-flow respirometry system was used to measure the resting metabolic rate (RMR) and the daily energy expenditure (DEE) of Chinese pangolins (Manis pentadactyla), and the dietary digestive energy was measured. The average RMR in Chinese pangolins was 3.23 ml O2 kg−1 min−1 at an ambient temperature (Ta) of 24.5–30°C, which was only 73.0% of the expected value based on body mass (BM). The average DEE values were 744.9 kJ day−1 in animals with BM >3 kg and 597.3 kJ day−1 in those with BM <3 kg, which were only 52.4% and 60.6% of the predicted values, respectively. The RMR and DEE levels of the Chinese pangolin were lower than those of similar-sized eutherian mammals and close to those of anteaters. These characteristics suggest that the Chinese pangolin has a low demand for energy in its diet. Although metabolic level data alone cannot be used to calculate the energy requirements of each Chinese pangolin, we believe they can provide a tangible reference for the relocation of Chinese pangolins. These results provide a scientific basis for future research on the physiology and ecology of endangered wildlife such as the Chinese pangolin.
APDB: a database on air pollutant characterization and similarity prediction
Authors: Viesi Eva , Sardina Davide Stefano , Perricone Ugo , Giugno Rosalba
Published: July 2023

The World Health Organization estimates that 9 out of 10 people worldwide breathe air containing high levels of pollutants. Long-term and chronic exposure to high concentrations of air pollutants is associated with deleterious effects on vital organs, including increased inflammation in the lungs, oxidative stress in the heart and disruption of the blood–brain barrier. For this reason, in an effort to find an association between exposure to pollutants and the toxicological effects observable on human health, an online resource collecting and characterizing in detail pollutant molecules could be helpful to investigate their properties and mechanisms of action. We developed a database, APDB, collecting air-pollutant-related data from different online resources, in particular, molecules from the US Environmental Protection Agency, their associated targets and bioassays found in the PubChem chemical repository and their computed molecular descriptors and quantum mechanics properties. A web interface allows (i) to browse data by category, (ii) to navigate the database by querying molecules and targets and (iii) to visualize and download molecule and target structures as well as computed descriptors and similarities. The desired data can be freely exported in textual/tabular format and the whole database in SQL format.

Database URL http://apdb.di.univr.it
Temperature-driven gene expression evolution in natural and laboratory populations highlights the crucial role of correlated fitness effects for polygenic adaptation
Authors: Thorhölludottir Dagny A V , Nolte Viola , Schlötterer Christian
Published: July 2023

The influence of pleiotropy on adaptive responses is a highly controversial topic, with limited empirical evidence available. Recognizing the pivotal role of the correlation of fitness effects, we designed an experiment to compare the adaptive gene expression evolution of natural and experimental populations. To test this, we studied the evolution of gene expression in response to temperature in two Drosophila species on a natural temperature cline in North America and replicated populations evolving in hot- and cold-temperature regimes. If fitness effects of affected traits are independent, pleiotropy is expected to constrain the adaptive response in both settings, laboratory and natural populations. However, when fitness effects are more correlated in natural populations, adaptation in the wild will be facilitated by pleiotropy. Remarkably, we find evidence for both predicted effects. In both settings, genes with strong pleiotropic effects contribute less to adaptation, indicating that the majority of fitness effects are not correlated. In addition, we discovered that genes involved in adaptation exhibited more pleiotropic effects in natural populations. We propose that this pattern can be explained by a stronger correlation of fitness effects in nature. More insights into the dual role of pleiotropy will be crucial for the understanding of polygenic adaptation.
An unusual active site architecture in cytochrome c nitrite reductase NrfA-1 from Geobacter metallireducens
Authors: Denkhaus Lukas , Siffert Fanny , Einsle Oliver
Published: July 2023

Dissimilatory nitrate reduction to ammonia (DNRA) is a central pathway in the biogeochemical nitrogen cycle, allowing for the utilization of nitrate or nitrite as terminal electron acceptors. In contrast to the competing denitrification to N2, a major part of the essential nutrient nitrogen in DNRA is retained within the ecosystem and made available as ammonium to serve as a nitrogen source for other organisms. The second step of DNRA is mediated by the pentahaem cytochrome c nitrite reductase NrfA that catalyzes the six-electron reduction of nitrite to ammonium and is widely distributed among bacteria. A recent crystal structure of an NrfA ortholog from Geobacter lovleyi was the first characterized representative of a novel subclass of NrfA enzymes that lacked the canonical Ca2+ ion close to the active site haem 1. Here, we report the structural and functional characterization of NrfA from the closely related G. metallireducens. We established the recombinant production of catalytically active NrfA with its unique, lysine-coordinated active site haem heterologously in Escherichia coli and determined its three-dimensional structure by X-ray crystallography to 1.9 Å resolution. The structure confirmed GmNrfA as a further calcium-independent NrfA protein, and it also shows an altered active site that contained an unprecedented aspartate residue, D80, close to the substrate-binding site. This residue formed part of a loop that also caused a changed arrangement of the conserved substrate/product channel relative to other NrfA proteins and rendered the protein insensitive to the inhibitor sulphate. To elucidate the relevance of D80, we produced and studied the variants D80A and D80N that showed significantly reduced catalytic activity.
The infinitesimal model with dominance
Authors: Barton Nicholas H , Etheridge Alison M , Véber Amandine
Published: July 2023

The classical infinitesimal model is a simple and robust model for the inheritance of quantitative traits. In this model, a quantitative trait is expressed as the sum of a genetic and an environmental component, and the genetic component of offspring traits within a family follows a normal distribution around the average of the parents’ trait values, and has a variance that is independent of the parental traits. In previous work, we showed that when trait values are determined by the sum of a large number of additive Mendelian factors, each of small effect, one can justify the infinitesimal model as a limit of Mendelian inheritance. In this paper, we show that this result extends to include dominance. We define the model in terms of classical quantities of quantitative genetics, before justifying it as a limit of Mendelian inheritance as the number, M, of underlying loci tends to infinity. As in the additive case, the multivariate normal distribution of trait values across the pedigree can be expressed in terms of variance components in an ancestral population and probabilities of identity by descent determined by the pedigree. Now, with just first-order dominance effects, we require two-, three-, and four-way identities. We also show that, even if we condition on parental trait values, the “shared” and “residual” components of trait values within each family will be asymptotically normally distributed as the number of loci tends to infinity, with an error of order 1/M. We illustrate our results with some numerical examples.
Quantifying circumpolar summer habitat for Antarctic krill and Ice krill, two key species of the Antarctic marine ecosystem
Authors: Merkel B , Trathan P , Thorpe S , Murphy E J , Pehlke H , Teschke K , Griffith G P
Published: July 2023

Antarctic krill (Euphausia superba) and Ice krill (Euphausia crystallorophias) are key species within Southern Ocean marine ecosystems. Given their importance in regional food webs, coupled with the uncertain impacts of climate change, the on-going recovery of krill-eating marine mammals, and the expanding commercial fishery for Antarctic krill, there is an increasing need to improve current estimates of their circumpolar habitat distribution. Here, we provide an estimate of the austral summer circumpolar habitat distribution of both species using an ensemble of habitat models and updated environmental covariates. Our models were able to resolve the segregated habitats of both species. We find that extensive potential habitat for Antarctic krill is mainly situated in the open ocean and concentrated in the Atlantic sector of the Southern Ocean, while Ice krill habitat was concentrated more evenly around the continent, largely over the continental shelf. Ice krill habitat was mainly predicted by surface oxygen concentration and water column temperature, while Antarctic krill was additionally characterized by mixed layer depth, distance to the continental shelf edge, and surface salinity. Our results further improve understanding about these key species, helping inform sustainable circumpolar management practices.
Critical Points of Polynomials With Roots on the Unit Circle
Authors: Ge Fan , Gonek Steven M
Published: July 2023

Let ${\mathcal {L}}(u)$ be a polynomial with all its roots on the unit circle. We establish an “angle duality” theorem relating the roots and critical points of ${\mathcal {L}}(u)$. As an application, we prove that if there is a large gap between roots of ${\mathcal {L}}(u)$, then most critical points of ${\mathcal {L}}(u)$ lie close to the unit circle. We also use our result to strengthen Sendov’s well-known conjecture for these special polynomials. Finally, we prove a sharp estimate for the location of the critical point near a small gap between roots of ${\mathcal {L}}(u)$.
Biology and management of hemp russet mite (Acari: Eriophyidae)
Authors: Brendan Hayes Christopher , Carter Olivia , Robert MacWilliams Jacob , Cranshaw Whitney , Chaparro Jacqueline M , Prenni Jessica E , Nachappa Punya
Published: July 2023

Hemp is rapidly becoming a crop of global agricultural importance, and one of the more serious pests of this crop is hemp russet mite (HRM) Aculops cannabicola (Acari: Eriophyidae). Significant knowledge gaps presently exist regarding critical aspects of pest biology, quantification of crop damage, and efficacy of pesticides. Here we assessed the role of cannabidiol (CBD) on HRM performance, efficacy of sulfur treatments in field trials, and effect of hot water immersion with and without surfactants in reducing HRM counts on hemp cuttings. We found that HRM fecundity was reduced on a high-CBD cultivar compared with a low-CBD cultivar in detached leaf assays. In contrast, HRM fecundity and survival were not impacted when reared on high-CBD diet in artificial feeding assays. This suggests that cannabinoids other than CBD may aid in reduction of mite populations on the high-CBD cultivar. Sulfur sprays reduced HRM populations by up to 98% with the greatest effects seen in plants receiving dual applications, one during the vegetative period in July and the second at the initiation of flowering in August. Yields of plants treated with sulfur increased by up to 33%, and there was a further increase in cannabinoid production by up to 45% relative to untreated plants. Hot water immersion treatments with and without surfactant solution reduced HRM on infested hemp cuttings, and no phytotoxicity was observed. This study provides novel approaches to mitigating HRM at multiple stages in hemp production.
InFluence: An Open-Source Python Package to Model Images Captured with Direct Electron Detectors
Authors: Mangan Gearóid Liam , Moldovan Grigore , Stewart Andrew
Published: July 2023

The high detection efficiencies of direct electron detectors facilitate the routine collection of low fluence electron micrographs and diffraction patterns. Low dose and low fluence electron microscopy experiments are the only practical way to acquire useful data from beam sensitive pharmaceutical and biological materials. Appropriate modeling of low fluence images acquired using direct electron detectors is, therefore, paramount for quantitative analysis of the experimental images. We have developed a new open-source Python package to accurately model any single layer direct electron detector for low and high fluence imaging conditions, including a means to validate against experimental data through computation of modulation transfer function and detective quantum efficiency.
A helium nova in the Large Magellanic Cloud – the faint supersoft X-ray source [HP99]159
Authors: Kato Mariko , Hachisu Izumi , Saio Hideyuki
Published: July 2023

We propose a helium nova model for the Large Magellanic Cloud (LMC) supersoft X-ray source (SSS) [HP99]159. This object has long been detected as a faint and persistent SSS for about 30 yr, and recently been interpreted to be a source of steady helium-shell burning, because no hydrogen lines are observed. We find that the object can also be interpreted as in a decaying phase of a helium nova. The helium nova is slowly decaying toward the quiescent phase, during which the observed temperature, luminosity, and SSS lifetime (≳30 yr) are consistent with a massive white dwarf model of ∼1.2 M⊙. If it is the case, this is the second discovery of a helium nova outburst after V445 Pup in our Galaxy, and also the first identified helium nova in the LMC. We also discuss the nature of the companion helium star in relation to Type Ia supernova progenitors.
Breeding season forest fragment size does not create negative carry-over for adult Wood Thrushes on fall migration timing or apparent annual survival
Authors: Boyd Brendan P , Hayes Sue , Israel Alexandra M , Stutchbury Bridget J M
Published: July 2023

Although carry-over effects related to wintering habitat quality are known to influence population dynamics of migratory songbirds, the presence of breeding season carry-over is understudied in full annual cycle models. To test whether forest fragment size on the breeding grounds can impose negative carry-over effects on a migratory songbird, we fitted adult Wood Thrush (Hylocichla mustelina) with 1-year coded radio-tags in forest fragments ranging from 16 to 499 ha in southwestern Ontario during the 2016–2019 breeding seasons and utilized automated telemetry via the Motus Wildlife Tracking System to record fall migration timing and returns the following spring (apparent annual survival). To examine short-term effects of fragment size on breeding females, during the 2018 and 2019 breeding seasons, we collected blood samples during incubation to measure corticosterone levels and tracked complete reproductive success and nest timing. We found that Wood Thrushes breeding in small forest fragments were not subject to strong negative effects on body condition (mass, corticosterone), reproductive success, or timing of the last nest of the season. We found that the onset of fall migration departure was not delayed for birds nesting in small fragments, and that apparent annual survival was not linked to breeding fragment size. This suggests that habitat differences linked to fragment size were not strong enough to trigger the kinds of negative carry-over effects (delayed migration, lower reproductive success) that have been documented in other species as a result of poor wintering-ground habitat quality. The strength of breeding fragment size-induced seasonal carry-over remains a critical gap in full annual cycle models for other declining migratory songbirds. Our findings suggest that while the importance of preserving large forested areas is often prioritized in conservation projects, small forest fragments can also have high conservation value.