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The composition of high rockfill dam materials is complex, and the mechanical parameters are uncertain and correlated in unknown ways due to the influences of the environment and construction, leading to complex deformation mechanisms in the dam–foundation system. Statistical characteristics of material parameters are the basis for deformation and stress analysis of high core rockfill dams, and using an inaccurate distribution model may result in erroneous analysis results. Furthermore, empirically evaluated distribution types of parameters are susceptible to the influence of small sample sizes, which are common in the statistics of geotechnical engineering. Therefore, proposing a multi-dimensional joint distribution model for parameters based on small-sample data is of great importance. This study determined the interval estimation values of Duncan–Chang E-B model parameters—such as the mean value and coefficient of variation for the core wall, rockfill, and overburden materials—using parameter statistical analysis, bootstrap sampling methods, and Akaike information criterion (AIC) optimization. Additionally, the marginal distribution types of each parameter were identified. Subsequently, a multi-dimensional joint distribution model for Duncan–Chang model parameters was constructed based on the multi-dimensional nonlinear correlation analysis of parameters and the Copula function theory. The application results for the PB dam demonstrate that joint sampling can effectively reflect the inherent correlation laws of material parameters, and that the results for stress and deformation are reasonable, leading to a sound evaluation of the cracking risk in the core wall of high core rockfill dams. [ABSTRACT FROM AUTHOR]

Surface ozone (O 3) is the primary air pollutant threatening global vegetation. It typically reduces the photosynthetic rate and stomatal conductance, leading to changes in carbon, water, and energy cycles; vegetation structure and composition; and climate. Several parameterization schemes have been developed to integrate the photosynthetic and stomatal responses to O 3 exposure in regional and global process-based models to simulate time- and space-varying O 3 plant damage and its cascading dynamic influence. However, these schemes are calibrated based on limited observations and often fail to reproduce the response relationships in observations, impeding accurate assessments of the role of O 3 plant damage in the Earth system. This study proposes a new parameterization scheme to utilize the extensive observations from O 3 fumigation experiments to inform large-scale modeling. It is built on 4210 paired data points of photosynthetic and stomatal responses compiled from the peer-reviewed literature, more than 6 times larger than those employed in earlier schemes. Functions of phytotoxic O 3 dose (POD) are found to accurately reproduce the statistically significant linear or nonlinear relationships observed between POD and either relative leaf photosynthetic rate or relative stomatal conductance for needleleaf trees, broadleaf trees, shrubs, grasses, and crops. These eliminate the practice in earlier schemes of setting response functions as constants and applying the response function from one vegetation type to another. It outperforms the old scheme in the Community Land Model (CLM), which skillfully reproduces the observed response for crop photosynthetic rate only. The nonlinear response functions we developed depict decreasing plant sensitivity with increases in POD, enabling models to implicitly capture the variability in plant ozone tolerance and the shift among plant species for both intra- and inter-PFTs (plant functional types) within a vegetation type observed in the real world. Then, the new scheme is incorporated into the Community Earth System Model version 2.2 (CESM2.2), specifically its land component CLM5, to quantify the global impacts of present-day O 3 plant damage by comparing the simulations with and without O 3 plant damage. Results show that O 3 exposure reduces the global leaf photosynthetic rate by 8.5 % and stomatal conductance by 7.4 %, around half the estimates using the old scheme. Furthermore, the new scheme improves global gross primary productivity (GPP) simulations, decreasing RMSE by 11.1 % relative to simulations without O 3 plant damage and by 11.7 % compared to the old scheme. These results underscore the importance of including O 3 plant damage in large-scale process-based models and the effectiveness of the new scheme in assessing and projecting globally the role of O 3 plant damage in the Earth system. [ABSTRACT FROM AUTHOR]

How obesity and elevated androgen levels in women with polycystic ovary syndrome (PCOS) affect their offspring is unclear. In a Swedish nationwide register-based cohort and a clinical case-control study from Chile, we found that daughters of mothers with PCOS were more likely to be diagnosed with PCOS. Furthermore, female mice (F.sub.0) with PCOS-like traits induced by late-gestation injection of dihydrotestosterone, with and without obesity, produced female F.sub.1-F.sub.3 offspring with PCOS-like reproductive and metabolic phenotypes. Sequencing of single metaphase II oocytes from F.sub.1-F.sub.3 offspring revealed common and unique altered gene expression across all generations. Notably, four genes were also differentially expressed in serum samples from daughters in the case-control study and unrelated women with PCOS. Our findings provide evidence of transgenerational effects in female offspring of mothers with PCOS and identify possible candidate genes for the prediction of a PCOS phenotype in future generations. Prenatal androgen exposure causes transgenerational increases in offspring susceptibility to polycystic ovary syndrome in adulthood., Author(s): Sanjiv Risal [sup.1] , Yu Pei [sup.1] [sup.2] , Haojiang Lu [sup.1] , Maria Manti [sup.1] , Romina Fornes [sup.1] , Han-Pin Pui [sup.1] , Zhiyi Zhao [sup.1] [sup.3] [...]

The precipitate phases of electron beam welded joint in GH141/GH907 superalloy dissimilar materials were studied by scanning electron microscopy (SEM), transmission electron microscope (TEM) and energy dispersive spectrometer (EDS). The welded joint contains GH141 heat affected zone, GH907 heat affected zone and weld area. The results indicate that there is no new precipitate phase in the heat affected zones of electron beam welding. Under the current heat treatment process, the precipitate phases of GH141 heat affected zone are square granular γ′ phases which are covered in matrix densely, thick massive MC type carbides with random distribution and the M6C type carbides which are precipitated mostly in the grain boundaries. Precipitate phases of GH907 heat affected zone are needle shaped ε phases covered in matrix densely and block G phases Nb3Ni2Si which are dispersed distribution. Precipitate phases of weld area are different from the two kinds of welding materials. One of them is a new needle shaped phase which has parallel or staggered distribution, and the other one is a tiny square or ellipsoid granular new precipitate phase which is proved to be orthogonal crystal system NbTi4 phase.

The widely distributed loess–mudstone strata structure in the Loess Plateau of China is one of the fundamental reasons for the susceptibility and group occurrence of seismic landslides in the area. This study took the loess landslides induced by the Haiyuan earthquake as a case study. Through extensive field investigations, the loess cover thickness, mudstone dip angle, slope height, and slope angle were chosen as the influencing factors. Together with mathematical statistics and geotechnical tests, two models, one of a loess–mudstone slope and the other of a pure loess slope, were constructed. Their seismic stabilities under different slope angles and slope heights were compared to analyze the influence of the underlying mudstone strata on the loess slope seismic stability. Meanwhile, a sensitivity analysis of these strata factors affecting the seismic stability of the loess–mudstone slope was carried out based on the orthogonal test. The results showed that ignoring the underlying mudstone strata would lead to smaller calculation results than the actual situation. The sensitivity influence of the factors on the loess–mudstone slope seismic stability comprised the slope angle, loess cover thickness, slope height, and mudstone dip angle from high to low. [ABSTRACT FROM AUTHOR]

The oxygen reduction reaction of the cathode in an Al-air battery plays a key role in the performance of the entire battery. Generally, Pt and its alloys are recognized as catalysts with high oxygen reduction catalytic performance, but their application is limited by the rare earth content and high cost. In this paper, α-MnO2 nanotubes are prepared using a hydrothermal method and used as a template. Nano-Ni–Mn bimetallic oxides with different compositions are prepared with different NiO and α-MnO2 ratios by calcination. The effects of morphology, phase, and Mn3+/Mn4+ and Ni3+/Ni2+ ratios on electrochemical performance and battery discharge performance are analyzed. The results show that the contents of α-MnO2 and Ni6MnO8 in NM-12 catalyst are low, and the molar ratio of Mn3+/Mn4+ and Ni3+/Ni2+ is high. Also, the specific surface area of NM-12 is relatively high. Finally, the catalyst prepared with a NiO to α-MnO2 ratio of 1:2 shows better electrochemical catalytic performance and battery discharge performance that is comparable to that obtained for a commercial 20 wt% Pt/C catalyst. [ABSTRACT FROM AUTHOR]

With the high penetration of renewable energy resources, power systems are facing increasing challenges in terms of flexibility and regulation capability. To address these, energy storage systems (ESSs) have been deployed on both transmission systems and distribution systems. However, it is hard to coordinate these ESSs with a single centralized optimization, and the time-domain coupling constraints of ESSs lead to high optimization complexity and a time-consuming calculation process. In this regard, this paper proposes a hierarchical transmission and distribution systems coordinative optimization framework, considering the ESSs at both ends of the systems. The decoupling of the time-domain coupling constraints of ESSs is realized by the Lyapunov optimization. Furthermore, the decoupling mechanism is embedded in the iterative process of analytical target cascading (ATC). In addition, an ATC-based Lyapunov optimization (ATC-L) approach is proposed to solve the co-optimization problem of the operations of the transmission system with multiple connected distribution systems. Through a case study, it is verified that the proposed framework and the ATC-L approach can effectively reduce the system's operational cost and improve the consumption rate of renewable energy. [ABSTRACT FROM AUTHOR]

Compares backgrounds and aspirations of teachers in China with teachers in America. Concludes that Chinese teachers generally come from less privileged backgrounds and are less likely to make teaching a lifelong career. Urges both Chinese and American policy makers to revise policies and practices in order to recruit and retain qualified teachers. (Contains 27 references.) (NB)

Abstract Background To evaluate basal testosterone (T) levels during follicular phase of the menstrual cycle as a predictor for ovarian response and in vitro fertilization (IVF) outcome. Method We analyzed data retrospectively from hospital-based IVF center including one thousand two hundred and sixty Chinese Han women under their first IVF cycle reached the ovum pick-up stage, without polycystic ovary syndrome (PCOS) or endometriosis undergoing long IVF protocol. Patients were divided into 2 groups. Group 1: patients with diminished ovarian reserve (basal FSH >10 IU/L) (n = 187); Group 2: patients with normal ovarian reserve (basal FSH < = 10 IU/L) (n = 1073). We studied the association of basal T levels with ovarian response and IVF outcome in the two groups. Long luteal down-regulation protocol was used in all patients, that is, the gonadotropin releasing hormone agonist was administered in the midluteal phase of the previous cycle and use of recombinant FSH was started when satisfactory pituitary desensitization was achieved. Results Basal T levels were markly different between pregnant and non-pregnant women in Group 1; whereas not in Group 2. A testosterone level of 47.85 ng/dl was shown to predict pregnancy outcome with a sensitivity of 52.8% and specificity of 65.3%; and the basal T was correlated with the numbers of large follicles (> 14 mm) on HCG day in Group 1. Significantly negative correlations were observed between basal T, days of stimulation and total dose of gonadotropins after adjusting for confounding factors in both groups. Conclusion In women with diminished ovarian reserve, basal T level was a predictor for the number of large follicles on HCG day and pregnancy outcome; but could not in those with normal serum FSH. Basal T levels were associated with both days of stimulation and total dose of gonadotropins, indicating that lower level of T might relate with potential ovarian poor response.

Gametogenetin binding protein 2 (GGNBP2) was indispensable in normal spermatids for transformation into mature spermatozoa in mice, and when Gametogenetin binding protein 2 is bound to BRCC36 and RAD51, the complex participates in repairing DNA double-strand breaks (DSB) during the meiotic progression of spermatocytes. Ggnbp2 knockout resulted in the up-regulation of H2A K119ubi and down-regulation of H2B K120ubi in GC-2 cells (mouse spermatogonia-derived cell line) and postnatal day 18 testis lysate. Our results also demonstrated that Gametogenetin binding protein 2 inducedASXL1 to activate the deubiquitinating enzyme BAP1 in deubiquitinating H2A, while Gametogenetin binding protein 2 knockout disrupted the interaction between ASXL1 and BAP1, resulting in BAP1 localization change. Furthermore, the Gametogenetin binding protein 2 deletion reduced H2B ubiquitination by affecting E2 enzymes and E3 ligase binding. Gametogenetin binding protein 2 regulated H2A and H2B ubiquitination levels and controlled H3 K27 and H3 K79 methylation by PRC2 subunits and histone H3K79 methyltransferase. Altogether, our results suggest that Ggnbp2 knockout increased DNA damage response by promoting H2A ubiquitination and H3 K27 trimethylation (H3 K27me3 ) and reduced nucleosome stability by decreasing H2B ubiquitination and H3K79 dimethylation (H3 K79me2 ), revealing new mechanisms of epigenetic phenomenon during spermatogenesis. Gametogenetin binding protein 2 seems critical in regulating histone modification and chromatin structure in spermatogenesis.

As a well-established analytical separation technique, capillary electrophoresis (CE) is widely used in the separation of chiral substances because of its numerous advantages such as high separation efficiency, short analysis time, small sample dosage, and flexible separation modes. In the previous studies, the CE separation mode, selection of the chiral dispersant and improvement of the separation degree of chiral compounds have been reported in detail. Moreover, it is important to determine the quality of chiral substances and confirm the order of enantiomer peaks after successful separation. This paper summarizes the qualitative detection methods for CE chiral compounds, based on whether the separation analysis of chiral compounds depends on the classification of standard materials. There are two common methods for the qualitative determination of chiral substances in CE. One method compares the difference in the peak migration time, while the other compares the change in peak area before and after the addition of a single enantiomer standard. Both methods are accurate and simple to operate. A diverse range of detectors are used in CE. Based on the type of detector, CE analysis based on standard products is divided into optical, mass spectrometric and electrochemical detection modes. Optical detection involves the use of ultraviolet-visible (UV-vis), laser-induced fluorescence (LIF), chemiluminescence (CL) and other detectors. Among these, the UV detector has the advantages of stable performance, simple structure, and high cost performance and it is most widely used in CE detection as one of the fixed commercial detectors. The LIF detector is a kind of fluorescence detector with a laser as an excitation source. It has the advantages of low background and high signal-to-noise ratio, which make it the most sensitive CE detector. However, this detector is expensive and the sample must be able to provide a fluorescence signal. Otherwise, it is necessary to use a derivatization reagent for sample pretreatment, which renders the analysis complicated. The type of detector leads to a difference in the sample pretreatment, and the resulting spectra and qualitative methods for chiral compounds are also widely different. Therefore, we must choose the most suitable detector to be combined with CE depending on the sample properties and experimental requirements. The above mentioned methods require at least one chiral molecular standard of one configuration. However, for many chiral enantiomers, especially some novel chiral drugs, there is no single commercially available standard enantiomer, and even if there is one, it is very expensive. In this case, the available CE chiral separation methods include enzyme digestion, addition of antibodies, and computational methods. Enzyme digestion entails the addition of refers to adding the corresponding degrading enzyme or oxidase into the tested sample, so that qualitative analysis is possible by observing the change in peak area. In the method based on antibody addition, it is necessary to find antibodies that respond to a single enantiomer. Nevertheless, it is difficult to acquire the corresponding digestion enzymes or specific antibodies for most chiral molecules. Hence, the application scope of these two methods is limited. On the other hand, the computational method is a chiral qualitative method that is rapid, economical, and simple to operate, with a wide range of applications. This technique combines the circular dichroism (CD) spectroscopy with theoretical calculations within the premise of CE separation. The underlying principle of this method covers two aspects. On the one hand, all chiral compounds can give CD signals, and a racemic mixture of isomers gives equal signals but with opposite signs. However, in the case of a non-racemic chiral isomer mixture, only the CD signal of the dominant isomers observed. Using the time-dependent density functional theory (TDDFT), the theoretical CD spectrum of a single isomer can be obtained. By comparing the theoretical and experimental spectra, the configuration of the dominant enantiomer is determined. On the other hand, the peak area in electrophoresis is linearly related to the enantiomeric excess in the CE spectrum. By combining CE with CD, accurate separation and qualitative detection of chiral substances can be easily achieved. The method of calculation, independent of the standard, will greatly promote the development of chiral molecular analysis.