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The Northwest Pacific Ocean is the most productive fishing ground in the Pacific Ocean, with a continuous rise in water temperature since 1990. We developed stacked species distribution models (SSDMs) to estimate the impacts of climate change on the distribution dynamics of economically significant species under three climate change scenarios for the periods 2040-2060 and 2080-2100. Overall, water temperature is the most important factor in shaping the distribution patterns of species, followed by water depth. The predictive results indicate that all the species show a northward migration in the future, and the migration distance varies greatly among species. Most pelagic species will expand their habitats under climate change, implying their stronger adaptability than benthic species. Tropical fishes are more adaptable to climate change than species in other climate zones. Though limitations existed, our study provided baseline information for designing a climate-adaptive, dynamic fishery management strategy for maintaining sustainable fisheries.

This paper attempts to reveal the freezing temperature and its influencing factors of heavy metal-contaminated loess by adopting two cooling methods: fast and slow grading. As a result, Lanzhou loess was used as an experimental material to make polluted soil with varying heavy metal concentrations and initial water content. The pollutant elements included Zn, Ni, Cu, Cr, Cd, and Pb. The findings demonstrate that: 1) The slow cooling rate causes supercooling, jumping, and a progressive decrease in the temperature of the polluted soil. Different cooling methods have no obvious effect on freezing temperature. Furthermore, the freezing temperature of contaminated soil varies depending on its water content. The impact of increasing water content on freezing temperature is not evident; 2) The freezing temperature of loess decreases with the increase of heavy metal ion content. The freezing temperature of loess polluted by Zn, Ni and Cd ions decreased linearly with the increase of ion content. The influence of cations on the freezing temperature of loess is as follows: Zn2+> Ni2+> Cd2+> Cr3+> Pb2+> Cu2+. The influence order of anions is Cl− > SO42−; 3) The freezing temperature of loess containing heavy metal ions is about equal to the freezing temperature of the corresponding heavy metal solution plus the freezing temperature of loess itself. The freezing temperature of heavy metal-polluted loess follows the temperature superposition principle.

In the Asian paddle crab (Charybdis japonica) gillnet fishery in the Yellow Sea, China, the minimum mesh size (MMS) regulation has been of a major importance due to high bycatch rates of undersized crabs. In this study, we evaluated how gillnet mesh size can affect the capture probability of C. japonica and capture patterns in this fishery by comparing the performance of gillnets with four different mesh sizes (60, 70, 80, and 90 mm). Our results showed that changes in gillnet mesh size significantly affect the capture probability of different sizes of crabs. Specifically, increased mesh size decreased the capture probability of undersized crabs and their fraction in the catches decreased from 64 % to 24 % when mesh size was increased from 60 mm to 90 mm. In contrast, gillnets with larger mesh sizes significantly improved the capture probability of legal-sized crabs. Moreover, no significant differences were observed for the species catch composition between gillnets of different mesh sizes. Based on these results, we recommend 90 mm as the MMS in gillnets to improve sustainability in C. japonica fishery.

Cracks are one of the most common diseases of tunnel lining, and the structural dynamic response can be used to assess the health of a tunnel. Hence, this paper investigates the dynamic response of shield tunnel lining with a partly circumferential crack. The shield tunnel lining is regarded as a thin cylindrical shell and analyzed independently. The research methodology integrates the wave propagation method, the local flexibility matrix, the line spring model and the wave superposition principle. The results show that the position and depth of a partly circumferential crack can influence the natural frequency of the shield tunnel lining. Under the fixed-position load, as the distance from the monitoring point to the crack increases, the difference in displacement response amplitude between the undamaged and cracked linings diminishes. Moreover, deepening cracks enlarge the magnitude of amplitude differences. When the load approaches the crack, the radial amplitude difference first increases and then decreases as the monitor moves away from the crack. This finding helps determine the required monitor position. The displacement response of the selected monitor indicates that the closer the load position is to the crack, the larger the amplitude difference. The results aid in identifying the crack position and selecting corresponding load and monitor locations.

The abnormal expansion of G-rich hexanucleotide repeat, GGGGCC (G4C2), in chromosome 9 open reading frame 72 (C9orf72) is known to be the prevailing genetic cause of two fatal degenerative neurological diseases, amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). It is well known that the DNA G4C2 repeat expansion with different lengths can form G-quadruplexes which affect gene transcription related to ALS/FTD, therefore it is crucial to understand DNA G4C2 G-quadruplex structures. Herein, by utilizing nuclear magnetic resonance (NMR) spectroscopy, we examined DNA G-quadruplex structure adopted by two G4C2 hexanucleotide repeats with an inosine substitution at position 4, d(G4C2)2-I4. We show that d(G4C2)2-I4 folds into an eight-layer parallel tetrameric G-quadruplex containing two parallel dimeric G-quadruplexes stacking together through π-π interaction via 5′-to-5′ mode in solution. Each dimeric G-quadruplex unit involves two propeller loops composed of two cytosine bases. This result is consistent with the observation in the crystal structure of d(G4C2)2. Our work not only sheds light on the structural diversity of G-quadruplexes adopted by d(G4C2)n but also provides a structural basis for drug design in treatment of ALS and FTD.

The small-scale trammel net fisheries are essential to the economy and well-being of coastal communities in the Yellow Sea, China. However, these fisheries are low efficient and urgently demand technical innovations to improve catch rates. In this study, we conducted field experiments in three traditional fishing grounds (Rizhao, Yantai, and Weihai) to test whether the addition of different colored light-emitting diodes (LEDs) fishing lights in the trammel nets could improve the catch rates of seven commercial species. Results showed that the effects of LEDs on catch rates were species-specific. Green LEDs could significantly increase the catch per unit effort (CPUE) of black rockfish (Sebastes schlegelii), fat greenling (Hexagrammos otakii), marbled flounder (Pseudopleuronectes yokohamae), stone flounder (Platichthys bicoloratus), Asian paddle crab (Charybdis japonica), and mantis shrimp (Oratosquilla oratoria) by 40%-72% compared with unilluminated nets, while had no significant effect on the catch rates of swimming crab (Portunus trituberculatus). Red LEDs harvested 58%-86% higher CPUE of fat greenling, marbled flounder, stone flounder, mantis shrimp, and swimming crab while catching fewer black rockfish and Asian paddle crab. Blue and white LEDs exhibited similar performance, which could significantly capture more black rockfish, fat greenling, and mantis shrimp and did not affect the catch rates of other species. The effects of LEDs were also size-dependent for certain species, and the catch rates generally increased with the length classes. Taking economic benefits into consideration, the green and red LEDs provided the highest profitability for Rizhao, while green LEDs performed best in Weihai and Yantai. This study is the first investigation on how artificial lights affected the catch rates of trammel nets. The findings of our study illustrated that trammel nets equipped with LEDs could serve as a viable fishing strategy in small-scale trammel net fisheries.

Several studies have demonstrated the importance of integrating intraspecific genetic variation in forecasting the habitat suitability of species under climate change scenarios. The Pacific cod (Gadus macrocephalus) is an economically important fish species in the North Pacific that can be classified into western and eastern populations based on molecular phylogeographic data. Herein, we first quantified the realized niche of the two Pacific cod populations using n-dimensional hypervolumes and estimated the niche differentiation between the populations. We then projected the habitat suitability based on the georeferenced occurrence records and environmental predictors using species distribution models (SDMs) at the population and species levels. The low niche overlap demonstrated the marked niche differentiation between the two populations. The distinct responses of the populations to climate predictors implied that the population-level SDM produced more reliable projections than the corresponding species-level SDM. The model indicated that the eastern population expanded its suitable area northward, while maintaining most of its current habitat and exhibited resilience to climate impacts. However, the western population lost much of its current suitable area, while colonizing a new habitat in a small section of the offshore waters of the Japanese Sea, implying the vulnerability of this population to climate change. This study highlights the necessity of incorporating intraspecific genetic variation into SDMs to predict the habitat suitability of Pacific cod on the global scale. The spatiotemporal predictive maps of habitat suitability provide crucial information for designing climate-adaptive conservation and management strategies based on more precise taxonomic units for the sustainability of Pacific cod.

Summary: The central step in the initiation of eukaryotic DNA replication is the loading of the minichromosome maintenance 2–7 (MCM2-7) complex, the core of the replicative DNA helicase, onto chromatin at replication origin. Here, we reported the cryo-EM structure of endogenous human single hexameric MCM2-7 complex with a resolution at 4.4 Å, typically an open-ring hexamer with a gap between Mcm2 and Mcm5. Strikingly, further analysis revealed that human MCM2-7 can self-associate to form a loose double hexamer which potentially implies a novel mechanism underlying the MCM2-7 loading in eukaryote. The high-resolution cryo-EM structure of human MCM2-7 is critical for understanding the molecular mechanisms governing human DNA replication, especially the MCM2-7 chromatin loading and pre-replicative complex assembly.

Climate change is exerting unprecedented effects on the habitats of marine mammals. Common minke whales (Balaenoptera acutorostrata) have suffered immense harm from commercial whaling, and the recovery of this species is likely threatened by climate change. To better manage and conserve this species, it is important to predict its current habitat distribution and the potential change under future climate change scenarios. Such predictions are typically generated by species distribution models (SDMs), which construct a correlation between species occurrence data and its habitat environmental variables. SDMs are commonly constructed at the species level, assuming a homogenous response of the species to climatic variables across their entire geographic range. Spatially segregated populations from the same species inhabit distinct environments and gradually adapt to the local conditions, resulting in niche differentiation among populations. Species-level SDMs that ignore the effects of local adaptation mask differences in population responses to climate change and might present an unrealistic picture of potential species distributions. Based on morphological and genetic evidence, the common minke whale was divided into three populations: the North Atlantic population (NAP), Southern Hemisphere population (SHP) and North Pacific population (NPP); these populations inhabit isolated geographic areas with distinct environmental conditions. We quantified the realized niches of these populations and found evidence of significant ecological niche differentiation. We then constructed SDMs at the species and population levels and compared the predictions from these two types of models under different climate change scenarios. Both types of models projected similar change trends in species range, with a contraction of future suitable habitats for the NAP and SHP and an expansion for the NPP. However, the magnitudes of this change differed; the population-level model projected more optimistic results for the SHP and NAP, indicating less habitat loss. This study highlighted the importance of considering local adaptation when estimating the impact of climate change on species habitat suitability. These spatiotemporal predictions provide essential knowledge for designing climate-adaptive conservation and management strategies, such as the delimitation of mobile marine protected areas (MPAs).

Electron-phonon coupling (EPC) is a key factor for thermoelectric properties of materials. In this paper, the thermoelectric properties of zinc-blende chalcogenides (p-type) ZnS and ZnSe have been studied through full evaluation of EPC from first-principles, including the influences on both electrical and thermal transport. We find that the polar longitudinal optical phonon scattering is the dominant mechanism for electrical transport. Due to the triple degeneracy near the valence band maximum, the inter-band scattering also has detrimental contributions to the electrical conductivities. For phonon transport, it shows that the lattice thermal conductivity can be reduced by the electron-phonon scattering significantly at high carrier concentrations (e.g., at 300 K with 1021 cm−3 of hole, the reduction is ∼24.9% for ZnS and ∼28.4% for ZnSe, respectively). Finally, the p-type thermoelectric figure of merit (ZT) of two systems have been obtained, which are 0.129 for ZnS and 0.141 for ZnSe, at 700 K with their respective optimal hole concentrations. Our work provides a complete and in-depth study of thermoelectric properties in chalcogenides ZnX from the role of EPC. The results suggest EPC plays an important role on the thermoelectric properties and thus full evaluation of EPC is necessary especially for polar materials.

Sustainable development of the important economic species, Asian paddle crab (Charybdis japonica), has attracted attention in the coastal waters of the Yellow Sea, China. The commonly used round pots are almost nonselective, resulting in severe bycatch of juveniles. In this study, we explored a method to improve the size selectivity for C. japonica by mounting escape vents on the side panels of each pot. The selectivity of pots with escape vent sizes of 70 mm × 20 mm, 70 mm × 25 mm, 70 mm × 30 mm, and 70 mm × 35 mm was tested using a catch comparison method. The estimated minimum landing size (MLS) of carapace height (27 mm), according to the regulated MLS of carapace length (50 mm), was used as a reference point to explain the results. Significant increases in the size of crabs caught by pots were found with the enlargement of escape vent size (Kruskal–Wallis test, P < 0.01). The pots with 70 mm × 20 mm, 70 mm × 25 mm and 70 mm × 30 mm escape vents released nearly 50%, 75% and 95% of undersized individuals, respectively, and these three types of pots retained approximately 90% of legal-sized individuals compared with the control pots without escape vents. The pots with 70 mm × 35 mm escape vents released nearly all undersized individuals, but they also released most legal-sized individuals. Pots with an escape vent size of 70 mm × 30 mm were recommended for the sustainable development of C. japonica in the Yellow Sea of China. The results of this study reiterate the importance of carapace height for determining the size selectivity, which can serve as a reference to formulate management regulations in the coastal waters of the Yellow Sea, China.

As IUCN critically vulnerable species,the Indo-Pacific humpback dolphins (Sousa chinensis) have attracted great public attention in recent years. The threats of human disturbance and environmental pollution to this population have been documented extensively. However, research on the sensitivity of this species to climate change is lacking. To understand the effect of climate change on the potential distribution of Sousa chinensis, we developed a weighted ensemble model based on 82 occurrence records and six predictor variables (e.g., ocean depth, distance to shore, mean temperature, salinity, ice thickness, and current velocity). According to the true skill statistic (TSS) and the area under the receiver operating characteristic curve (AUC), our ensemble model presented higher prediction precision than most of the single-algorithm models. It also indicated that ocean depth and distance to shore were the most important predictors in shaping the distribution patterns. The projections for the 2050s and 2100s from our ensemble model indicated a severe adverse impact of climate change on the Sousa chinensis habitat. Over 75% and 80% of the suitable habitat in the present day will be lost in all representative concentration pathway emission scenarios (RCPS) in the 2050s and 2100s, respectively. With the increased numbers of records of stranding and deaths of Sousa chinensis in recent years, strict management regulations and conservation plans are urgent to safeguard the current suitable habitats. Due to habitat contraction and poleward shift in the future, adaptive management strategies, including designing new reserves and adjusting the location and range of reserves according to the geographical distribution of Sousa chinensis, should be formulated to minimize the impacts of climate change on this species.

Abstract In this paper, a class of mixed nonlinear impulsive differential equations is studied. When the delay σ(t) $\sigma(t)$ is variable, each given interval is divided into two parts on which the quotients of x(t−σ(t)) $x(t-\sigma(t))$ and x(t) $x(t)$ are estimated. Then, by introducing binary auxiliary functions and using the Riccati transformation, several Kamenev type interval oscillation criteria are established. The well-known results obtained by Liu and Xu (Appl. Math. Comput. 215:283–291, 2009) for σ(t)=0 $\sigma(t)=0$ and by Guo et al. (Abstr. Appl. Anal. 2012:351709, 2012) for σ(t)=σ0 $\sigma(t)=\sigma_{0}$ ( σ0≥0 $\sigma_{0}\geq0$) are developed. Moreover, an example illustrating the effectiveness and non-emptiness of our results is also given.

The swing behaviour of tower cranes under compound working conditions is closely related to construction safety and structural health. This paper presents dynamic models and simulated them for parameter analysis to understand tower cranes’ dynamic characteristics and vibration features under compound working conditions. The parameters contain payload mass, rope length, lifting acceleration, slewing acceleration, luffing acceleration, and initial angle. For the lifting-luffing coupling motion (LLCM) and lifting-slewing coupling motion (LSCM) of the tower crane, the D’Alembert principle provides a theoretical basis for the derivation of system dynamics equations. The spatial swing angle description of the crane payload includes the time-domain response and frequency-domain response, which uses a dynamic model. The result shows that the mass has little effect on the spatial swing angle. The value of the lifting acceleration is stable at 0.004 m/s2 to 0.01 m/s2. Peak value (PV), root mean square value (RMS), root mean square frequency (RMSF), and frequency standard deviation (RVF) present the best sensitivity to changes in the spatial swing angle response. When PV of angles θ and β increases by tens of thousands of times in the LLCM, PV can reflect the phenomenon of angle divergence. The skewness value (SV) increases by 3422% at the severe swing angle performance in the LSCM. The swing angle regularity with the compound working conditions can provide theoretical guidance for eliminating structural vibration.

Summary: Eukaryotic DNA replication licensing is a prerequisite for, and plays a role in, regulating genome duplication that occurs exactly once per cell cycle. ORC (origin recognition complex) binds to and marks replication origins throughout the cell cycle and loads other replication-initiation proteins onto replication origins to form pre-replicative complexes (pre-RCs), completing replication licensing. However, how an asymmetric single-heterohexameric ORC structure loads the symmetric MCM (minichromosome maintenance) double hexamers is controversial, and importantly, it remains unknown when and how ORC proteins associate with the newly replicated origins to protect them from invasion by histones. Here, we report an essential and cell-cycle-dependent ORC “dimerization cycle” that plays three fundamental roles in the regulation of DNA replication: providing a symmetric platform to load the symmetric pre-RCs, marking and protecting the nascent sister replication origins for the next licensing, and playing a crucial role to prevent origin re-licensing within the same cell cycle. : Amin et al. provide in vivo evidence for an essential, cell-cycle-dependent, and likely semi-conservative ORC dimerization cycle that regulates eukaryotic chromosomal DNA replication. ORC dimers provide symmetric platforms to load the symmetric pre-RCs at replication origins. ORC de-dimerization produces two single hexamers to bind and protect the two nascent origins. Keywords: DNA replication, replication licensing, pre-RC formation, cell-cycle control, ORC dimerization

The traction drive system of a high-speed train has a vital role in the safe and efficient operation of the train. This paper established an electromechanical coupling model of a high-speed train. The model considers the interaction of the gear pair, the equivalent connecting device of the transmission system, the equivalent circuit of the traction motor, and the direct torque control strategy. Moreover, the numerical simulation of the high-speed train model includes constant speed, traction, and braking conditions. The results indicate that the meshing frequency and the high harmonics rotation frequency constitute the stator current. Furthermore, both frequencies are evident during constant speed. However, they are blurry among other conditions except for twice the rotation frequency. Meanwhile, the rotor and stator currents’ root-mean-square (RMS) values during traction are less than the RMS value during braking. The initiation of traction and braking causes a significant increase in current. During the traction and braking process, the RMS value of the current gradually decreases. Therefore, it is necessary to pay attention to the impact of the transition process on system reliability.

Background Global regression models under an implicit assumption of spatial stationarity were commonly applied to estimate the environmental effects on aquatic species distribution. However, the relationships between species distribution and environmental variables may change among spatial locations, especially at large spatial scales with complicated habitat. Local regression models are appropriate supplementary tools to explore species-environment relationships at finer scales. Method We applied geographically weighted regression (GWR) models on Yellow Perch in Lake Erie to estimate spatially-varying environmental effects on the presence probabilities of this species. Outputs from GWR were compared with those from generalized additive models (GAMs) in exploring the Yellow Perch distribution. Local regression coefficients from the GWR were mapped to visualize spatially-varying species-environment relationships. K-means cluster analyses based on the t-values of GWR local regression coefficients were used to characterize the distinct zones of ecological relationships. Results Geographically weighted regression resulted in a significant improvement over the GAM in goodness-of-fit and accuracy of model prediction. Results from the GWR revealed the magnitude and direction of environmental effects on Yellow Perch distribution changed among spatial locations. Consistent species-environment relationships were found in the west and east basins for adults. The different kinds of species-environment relationships found in the central management unit (MU) implied the variation of relationships at a scale finer than the MU. Conclusions This study draws attention to the importance of accounting for spatial nonstationarity in exploring species-environment relationships. The GWR results can provide support for identification of unique stocks and potential refinement of the current jurisdictional MU structure toward more ecologically relevant MUs for the sustainable management of Yellow Perch in Lake Erie.

Glass fiber reinforced polyolefin composite materials have many advantages regarding their performance and have been widely used in many fields. However, there are few reports on the simultaneously bidirectional self-enhancement of glass fiber reinforced polyethylene/polypropylene composite pipe. To self-reinforce the pipe’s circular and axial properties simultaneously, short glass fiber reinforced high-density polyethylene/polypropylene (SGF/HDPE/PP) pipes were extruded using a shearing–drawing two-dimensional compound stress field pipe-extrusion device. The effects of the rotating speed of the rotating shear sleeve on the orientation, heat behavior, microstructure, and tensile strength of the pipe were investigated in this paper. The microstructure was observed using scanning electron microscopy (SEM), and the crystal diffraction was analyzed using a polycrystalline X-ray diffractometer (WAXD), the heat behavior was measured using a differential scanning calorimeter (DSC), and the tensile strength was tested using a universal electronic tensile testing machine. The results showed that the shear induction effect induced by the shear rotating promoted the formation of the oriented structure of the crystal plate and SGFs along the circular and axial directions of the pipe simultaneously. Furthermore, it increased the crystallinity of the system, and self-improved the pipe’s circular and axial tensile strength at the same time.