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• In grid-connected PV systems, the synthetic current signal is seriously affected by extra multicomponent noises. • Due to the noise signal synthesis influence, the existing Db9-based features would become invalid. • The established Rbio3.1-based features directly focus on the arc fault instead of synthetic signal. • The proposed protection strategy could adapt to different PV systems even without adjusting parameters. • The proposed protection strategy could achieve the effective arc fault detection. The arc fault protection strategy should be applied in grid-connected photovoltaic (PV) systems to guarantee the human and equipment safety. In this paper, PV series arc faults are conducted in different grid-connected PV systems through the designed experimental platform firstly. Having analyzed these synthetic arc fault current signals through the existing Db9-based features used in the resistive system, the amplitude is found no longer increasing during the arc fault period in some frequency bands. Inverters would inject extra multicomponent noises to influence electrical characterization of arc faults in grid-connected PV systems, causing that Db9-based features show undesirable constant even decreasing amplitude patterns. Next, the Rbio3.1-based features have the better symmetric property to achieve the singularity detection of arc faults. The biorthogonality property of Rbio3.1 could further improve the reconstruction accuracy cooperating with the symmetric property. Besides, its higher vanishing moment is able to display the arc salient disturbances more clearly. Then the Rbio3.1 is able to give more arc fault occurrence time discovery pulses and better arc fault separation degree for different switching frequencies, inverter types, and inverter stages. Ideally, its feature improvement ability may not appear under fault-like conditions. Finally, the random forest (RF) outputs the final state recognition result through combining multiple classifications without adjusting parameters. For the desired Rbio3.1-based features, different feature combinations are able to significantly improve the detection accuracy at the acceptable speed for complicated interference scenes in multiple grid-connected PV systems based on the MATLAB platform. [ABSTRACT FROM AUTHOR]

Acheulian tools with their associated level of cognizance heralded a major threshold in the evolution of hominin technology, culture and behavior. Thus, unraveling occurrence ages of Acheulian technology across different regions worldwide constitutes a key aspect of understanding the archeology of early human evolution. Here we present a magneto-cyclochronology for the Acheulian assemblage from Sanmenxia Basin, Loess Plateau, North China. Our results place a sequence of stable normal and reversed paleomagnetic polarities within a regional lithostratigraphic context. The Acheulian assemblage is dated to be older than the Matuyama–Brunhes boundary at 0.78 Ma, and is found in strata that are probably equivalent to a weak paleosol subunit within loess layer L 9 in the Chinese loess-paleosol sequence, which corresponds to marine isotope stage (MIS) 23, a relatively subdued interglacial period with age range of ∼0.89–0.92 Ma. This age of ∼0.9 Ma implies that Acheulian stone tools were unambiguously present in North China during the Early Pleistocene. It distinctly enlarges the geographic distribution of Acheulian technology and brings its occurrence in North China back into the Early Pleistocene, which is contemporaneous with its first emergence in Europe. Combined with other archeological records, the larger area over which Acheulian technology existed in East Asia during the terminal Early Pleistocene has important implications for understanding early human occupation of North China. [ABSTRACT FROM AUTHOR]

Abstract: We present a computationally-efficient method for obtaining the fully spun-up state of a seasonally-varying global ocean biogeochemistry model. The solver uses a Newton–Krylov method to find the fixed points of the map that assigns to an initial state the value of the model state at the end of a one-year run. Apart from the preconditioner, which we describe in the paper, the method relies on a black-box public-domain Newton–Krylov solver that does not require the explicit construction of the model’s Jacobian matrix. Applied to the PO4 plus dissolved organic phosphorus (DOP) cycle of an Ocean Carbon Model Intercomparison Project II (OCMIP-2) type model, the solver is more than two orders of magnitude faster than the traditional time-stepping method for spinning up the model. The efficiency of the solver is illustrated by using the seasonally varying globally-gridded PO4 climatology to objectively optimize the parameters that control the mean lifetime of semi-labile DOP and the fraction of new production allocated to DOP. The optimization study demonstrates that the information in the seasonal variations of do not provide a significantly stronger constraint than the annually averaged data used in previous optimization studies. [Copyright &y& Elsevier]

Abstract: An adjoint data assimilation approach was used to quantify the physical and biological controls on Calanus finmarchicus N3–C6 stages on Georges Bank and its nearby environs. The mean seasonal cycle of vertically averaged distributions, from 5 years of the GLOBEC Georges Bank Broad-Scale Surveys between January and June, was assimilated into a physical–biological model based on the climatological circulation. Large seasonal and spatial variability is present in the inferred supply sources, mortality rates, computed molting fluxes, and physical transports. Estimated mortalities fall within the range of observed rates, and exhibit stage structure that is consistent with earlier findings. Inferred off-bank initial conditions indicate that the deep basins in the Gulf of Maine are source regions of early stage nauplii and late-stage copepodids in January. However, the population increase on Georges Bank from January to April is controlled mostly by local biological processes. Magnitudes of the physical transport terms are nearly as large as the mortality and molting fluxes, but their bank-wide averages are small in comparison to the biological terms. The hypothesis of local biological control is tested in a sensitivity experiment in which upstream sources are set to zero. In that solution, the lack of upstream sources is compensated by a decrease in mortality that is much smaller than the uncertainty in observational estimates. [Copyright &y& Elsevier]

The Tibetan Plateau is known as the rooftop of the planet. Its hypoxic atmosphere in low oxygen partial pressure, extreme seasonal climate variation, and aridity poses severe challenges as harsh living environments for prehistoric human to occupy in such high-altitude niches. However, the Lake Qinghai is the largest lake on the Tibetan Plateau and the basin has rich water, mineral, and wild food resources, and prehistoric human occupied the Lake Qinghai Basin long before local farming was in practice. In this paper we present results of faunal assemblages associated with variable stone artifacts and pottery shards with bone collagen accelerator mass spectrometry radiocarbon (AMS 14C) dates from 3 new archaeological sites to investigate human occupation history in the southern Lake Qinghai Basin. The AMS 14C dating results reveal that the occupation occurs intermittently from the late Glacial to entire Holocene. Through compilation and synthesis of regional archaeological records, we found that prehistoric humans went through 3 phases of subsistence strategies: 1) hunting large and medium ungulates; 2) hunting medium ungulates; 3) foraging small size mammals with birds and fish diets. At the end, prehistoric humans increasingly adapted to forage and consume caprinaes species (goat), which represents a precursor of domestication or semi-domestication of wild animals in the Lake Qinghai Basin. We further attribute the utilization of caprinaes animal resources to the lower limbs of toe and phalange bones with low nutritious values to advanced social organization that implied prehistoric humans separated hunting activity from protein processing practices. Our investigation of zooarchaeology with reliable bone collagen AMS 14C dates could become a novel approach to study adaptation strategy and social structure changes of prehistorical Tibetan humans. [ABSTRACT FROM AUTHOR]

• The DC side voltage level of the system has been continuously improved in PV and PEDF system, it has developed towards DC3000V. This puts forward new requirements to higher voltage (>DC1500 V) DC circuit breakers for DC side short-circuit fault protection. Based on this, a self-powered hybrid DC circuit breaker with synergistic effect of step-down and divided current is proposed, which uses the voltage of the main branch to trigger IGBT conduction that can achieve commutation without additional trigger circuit. The interruption characteristics is analyzed by simulation. The voltage division of the reactor and the shunt function of the shunt resistance during the fault breaking process can not only reduce the current peak of the main branch and the transfer branch, but also greatly reduce the voltage that the mechanical switch needs to withstand, reduce the probability of post-arc reignition, and shorten the interruption time of the circuit breaker. The circuit breaker topology proposed in this paper can realize the interruption of the DC arc at larger fault current and higher voltage. It provides guidance for hybrid DC circuit breaker used to complete fault interruption in renewable energy power systems. The DC voltage level of photovoltaic and PEDF applications have continuously advanced, reaching up to DC3000V. This presents new requirements for DC circuit breakers operating at higher voltages (>DC1500V) to ensure effective fault protection in the DC side. Based on this, a self-powered hybrid DC circuit breaker with synergistic effect of step-down and divided current is proposed. This innovative design utilizes the voltage of main branch to trigger IGBT conduction, eliminating the need for an additional trigger circuit. The interruption characteristics is analyzed by simulation. The reactor and shunt resistance effectively reduce the peak currents of both main and transfer branches. This approach significantly mitigates the voltage stress on the mechanical switch, reduces the risk of post-arc reignition, and shortens the interruption time. The circuit breaker topology proposed enables the DC arc interruption at larger current and higher voltage, serving as the valuable guide for the implementation of hybrid DC circuit breakers in renewable energy power systems. [ABSTRACT FROM AUTHOR]

The Tibetan Plateau is the world's largest high-elevation ecosystem. Here, we present evidence of stone artefacts from an in-situ stratigraphic sequence with the accelerator mass spectrometry 14C and optically stimulated luminescence dates to show that the sophisticated microlithic technologies emerged on the central Tibetan Plateau (CTP) as early as 6800 years ago. The "high-valued" and rarely seen obsidian artefacts at the study site may have come from the perimeter Tibetan Plateau (PTP). We found that cultures exchanged frequently between the CTP and PTP populations and their social networks and information sharing systems were more organised than previously thought among early TP populations. • 14C and OSL dates show that the sophisticated microlithic technologies emerged on the CTP as early as 6800 years ago. • LD15 is one of the earliest microblade sites at the central high-altitude Tibetan Plateau. • Social network and information sharing system among the early TP populations were more organized than previous thought. [ABSTRACT FROM AUTHOR]

• The interaction of C 4 F 7 N with α-Al 2 O 3 (0001) surface belongs to chemisorption. • The dissociation of C 4 F 7 N on α-Al 2 O 3 surface is difficult to occur. • C 4 F 7 N and α-Al 2 O 3 shows good thermal compatibility below 170 ℃. • The α-Al 2 O 3 -based materials can be used as insulators in C 4 F 7 N-filled electrical equipment. In this paper, the compatibility between C 4 F 7 N and α-Al 2 O 3 (0001) surface has been evaluated based on the density functional theory (DFT). The adsorption energy, total charge transfer, states analysis, and electron density difference were obtained to analyze the interaction behavior of C 4 F 7 N on α-Al 2 O 3 (0001) surface. The results demonstrated a chemisorption between C 4 F 7 N and α-Al 2 O 3 (0001) surface. Moreover, the pathway of C 4 F 7 N dissociated on α-Al 2 O 3 (0001) surface after the adsorption was determined. However, the activation energy required for the dissociation is too large to achieve, which means that the dissociation of C 4 F 7 N on α-Al 2 O 3 surface is difficult to occur. Additionally, the thermal compatibility between α-Al 2 O 3 and C 4 F 7 N were verified by experiments, which shows a certain compatibility between C 4 F 7 N and α-Al 2 O 3 (0001) under up to 170 ℃. The results demonstrate that α-Al 2 O 3 -based materials can be used as insulators in C 4 F 7 N-filled electrical equipment. [ABSTRACT FROM AUTHOR]

P-glycoprotein (P-gp) efflux assay is an integral part of discovery screening, especially for drugs requiring brain penetration as P-gp efflux ratio (ER) inversely correlates with brain exposure. However, significant variability in P-gp ER generated across cell lines can lead to misclassification of a P-gp substrate and subsequently disconnect with brain exposure data. We hypothesized that the ER depends on P-gp protein expression level in the in vitro assay. Quantitative proteomics and immunofluorescence staining were utilized to characterize P-gp protein expression and localization in four recombinant cell lines, over-expressing human or mouse P-gp isoforms, followed by functional evaluation. Efflux data generated in each cell line was compared against available rodent brain distribution data. The results suggested that the cell line with highest P-gp expression (hMDCK-MDR1 sourced from NIH) led to greatest dynamic range for efflux; thus, proving to be the most sensitive model to predict brain penetration. Cell lines with lower P-gp expression exhibited the greatest tendency for compound-dependent in vitro efflux saturation leading to false negative results. Ultimately, P-gp kinetics were characterized using a compartmental model to generate system-independent parameters to resolve such discrepancy. This study highlights the need for careful choice of well characterized P-gp in vitro tools and utility of modeling techniques to enable appropriate interpretation of the data. [ABSTRACT FROM AUTHOR]

• The moisture absorption, chemical, and electrical properties of silicone gel under 85 °C&85%RH with long aging time is characterized. • The "depth effect" is discovered which shows the wettest position locates at the mid-depth in silicone gels after desorption. • The "delayed degradation effect" is discovered which shows the effect of moisture intrusion on electrical performance degradation is delayed. In the applications of offshore wind turbines and high-speed trains, the power electronic devices suffer in harsh working conditions of high humidity. The moisture invades devices and induces failure of power modules. Therefore, it is necessary to investigate the degradation behaviors of encapsulation material with moisture intrusion. In this paper, the moisture absorption, chemical, and electrical properties of silicone gel under 85 °C&85%RH with long aging time is characterized. And the aging at 85 °C is chosen as a control. The influence of moisture absorption on the performance of silicone gel is discussed. The results showed that the wettest position locates at the mid-depth in silicone gels after desorption, which can be called as "depth effect" and is first discovered. Besides that, the mass loss during the aging is also observed and a comprehensive explanation considering the competition of absorption and dissolution is given here. Furthermore, a new phenomenon defined as "delayed degradation effect" is discovered. It is that the effect of moisture intrusion on electrical performance degradation in thin samples is delayed. In conclusion, moisture intrusion will degrade the electrical properties of silicone gel, so attention should be paid to power electronic devices working in high humidity conditions. [ABSTRACT FROM AUTHOR]

Abstract: Herein the discovery of a novel class of aminoheterocyclic Nav1.7 antagonists is reported. Hit compound 1 was potent but suffered from poor pharmacokinetics and selectivity. The compact structure of 1 offered a modular synthetic strategy towards a broad structure–activity relationship analysis. This analysis led to the identification of aminopyrazine 41, which had vastly improved hERG selectivity and pharmacokinetic properties. [Copyright &y& Elsevier]

Abstract: Clinical genetic data have shown that the product of the SCN9A gene, voltage-gated sodium ion channel Nav1.7, is a key control point for pain perception and a possible target for a next generation of analgesics. Sodium channels, however, historically have been difficult drug targets, and many of the existing structure–activity relationships (SAR) have been defined on pharmacologically modified channels with indirect reporter assays. Herein we describe the discovery, optimization, and SAR of potent aminopyrimidinone Nav1.7 antagonists using electrophysiology-based assays that measure the ligand–receptor interaction directly. Within this series, rapid functionalization at the polysubstituted aminopyrimidinone head group enabled exploration of SAR and of pharmacokinetic properties. Lead optimized N-Me-aminopyrimidinone 9 exhibited improved Nav1.7 potency, minimal off-target hERG liability, and improved rat PK properties. [Copyright &y& Elsevier]

Abstract: A series of α-amidosulfones were found to be potent and selective agonists of CB2. The discovery, synthesis, and structure–activity relationships of this series of agonists are reported. In addition, the pharmacokinetic properties of the most promising compounds are profiled. [Copyright &y& Elsevier]

Abstract: Structural modifications to the central portion of the N-arylamide oxadiazole scaffold led to the identification of N-arylpiperidine oxadiazoles as conformationally constrained analogs that offered improved stability and comparable potency and selectivity. The simple, modular scaffold allowed for the use of expeditious and divergent synthetic routes, which provided two-directional SAR in parallel. Several potent and selective agonists from this novel ligand class are described. [Copyright &y& Elsevier]

• Comprehensively optimized of time settings, energy ratio and spot size in DPFO-LIBS. • Reduced the self-absorption of matrix Fe, while improving the SNR of trace Cr. • Achieved spectral enhancement without significantly increasing ablation mass. • Established quantification by IS, PLSR and RFR with performance verified by LOOCV. • Obtained the concentration mapping of Cr with the prediction error below 200 wt.%. Remote and on-line measurement of chromium on structural steel surface in nuclear power plants is critical for protection against fluid accelerated corrosion. To improve the insufficient sensitivity of fiber-optic laser-induced breakdown spectroscopy toward trace element detection, a dual-pulse spectral enhancement system is set up. In an iron matrix, for the purpose of improving sensitivity of trace chromium analysis and reducing the self-absorption of iron, the effects of key parameters are investigated. The optimal values of the parameters are found to be: 450 ns inter-pulse delay, 700 ns gate delay, 30 mJ/6 mJ pulse energy ratio, and 19.8 mm lens-to-sample distance (corresponding to a 799 μm laser focused spot size). Compared to the single-pulse system, the shot number of dual-pulse ablation is limited for reducing surface damage. After the optimization of the dual-pulse system, the signal-to-noise ratio of the trace chromium emission line has been improved by 3.5 times in comparison with the single-pulse system, and the self-absorption coefficient of matrix iron has been significantly reduced with self-reversal eliminated. The number of detectable lines for trace elements has more than doubled thus increasing the input for spectral calibration without significantly increasing the ablation mass. Three calibration methods including internal standardization, partial least squares regression and random forest regression are employed to determine the chromium and manganese concentrations in standard samples of low alloy steel, and the limit of detection is respectively calculated as 36 and 515 ppm. The leave-one-out cross validation method is utilized to evaluate the accuracy of chromium quantification, and the concentration mapping of chromium is performed on the surface of a steel sample (16MND5) with a relative error of 0.02 wt%. [ABSTRACT FROM AUTHOR]

Abstract: Stable and orally bio-available pro-drugs of CPS11 were synthesized. They are active on human umbilical vein endothelial cell proliferation assay and tube formation assay. The therapeutic efficacy and safety of 4 as a single agent or combined with Taxol in the treatment of MX-1 human breast cancer xenograft were evaluated. Compound 4 as a single agent failed to produce an anti-tumor activity, while it significantly enhanced antitumor potency of Taxol. [Copyright &y& Elsevier]

• C 5 F 10 O starts to decompose at 500 ℃ and CO 2 , C 3 F 6 , and C 4 F 10 are dominant by-products. • A unique by-products C 2 F 6 O 3 is produced under partial discharge in C 5 F 10 O-air mixture. • Decomposition products CF 4 , C 3 F 6 , CF 2 O, CHF 3 , and C 3 HF 7 have good compatibility with Al (1 1 1) and Cu (1 1 1) surfaces. • The O atoms in C 2 F 6 O 3 show strong reaction activity with Al (1 1 1) and Cu (1 1 1) surfaces. Perfluoroketone C 5 F 10 O has drawn much attention in recent years as a promising environmental-friendly gas to substitute SF 6 in power equipment. In this paper, the decomposition characteristics of C 5 F 10 O and C 5 F 10 O/air mixture under pyrolysis and partial discharge conditions were explored by experiments using a gas chromatography/mass spectrometer. Besides, the compatibility of decomposition products with the copper and aluminum was evaluated based on the density functional theory calculation. We found that C 5 F 10 O has good thermal stability at 300 ℃. At 500 ℃, C 5 F 10 O starts to decompose and it produces CO, CO 2 , C 2 F 6 , C 2 F 4 , C 3 F 8 , C 3 F 6 , C 4 F 10 , C 4 F 8 and CHF 3 , among which CO 2 , C 3 F 6 , and C 4 F 10 are dominant. For C 5 F 10 O/air mixtures, the pyrolysis products are mainly saturated fluorocarbons and more CO 2 is produced. Partial discharges in C 5 F 10 O/air mixture mainly produce CO 2 , saturated fluorocarbons and a unique compound C 3 F 6 O 3. It is found that CF 4 , C 3 F 6 , CF 2 O, CHF 3 , and C 3 HF 7 have good compatibility with Al (1 1 1) and Cu (1 1 1) surfaces, while the interactions between C 2 F 6 O 3 and Al (1 1 1), Cu (1 1 1) surfaces are relatively strong, which are chemisorption. The identified by-products of C 5 F 10 O and C 5 F 10 O/air mixture under different conditions as well as their compatibility with metal materials is essential for online fault-diagnostic and long-term maintenance in engineering applications. [ABSTRACT FROM AUTHOR]

• Interaction between C4F7N and ZnO surface is stronger that on Zn surface. • The CN group shows a strong activity on the ZnO surface. • Activation energy of C 4 F 7 N dissociation on ZnO surface is higher than on Cu and Al. • Zinc shows potentials to be anti-corrosion material when using C 4 F 7 N. Recently, C 4 F 7 N has been considered as one of the most promising candidates to replace SF 6 due to its excellent insulation performance and environmental-friendly property. Metal zinc is widely used as a coating material in gas-insulated electrical equipment. However, its compatibility with C 4 F 7 N has never been explored before. In this paper, the adsorption properties of C 4 F 7 N on Zn(0 0 0 1) and ZnO(1 0 1 ¯ 0) surfaces were theoretically studied by a first-principles calculation. Adsorption energy, total charge transfer, density of states, and electron density difference were calculated to evaluate the compatibility of C 4 F 7 N with Zn and ZnO. The results demonstrated that the interaction between C 4 F 7 N and ZnO(1 0 1 ¯ 0) is stronger than that of Zn(0 0 0 1). The dissociation pathway of C 4 F 7 N after adsorption on the ZnO(1 0 1 ¯ 0) surface was also determined, which shows that ZnO(1 0 1 ¯ 0) has a catalytic effect on the decomposition process of C 4 F 7 N. Compared with Al(1 1 1) and Cu(1 1 1), the dissociation of C 4 F 7 N on ZnO(1 0 1 ¯ 0) has a higher energy barrier, indicating that the reaction is more difficult to occur. As a result, Zn and ZnO have certain compatibility with C 4 F 7 N, which was also verified by experiments. Therefore, we infer that Zn shows potentials to be used as anti-corrosion coating in C 4 F 7 N gas-insulated electrical equipment. [ABSTRACT FROM AUTHOR]