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It is imperative for the mining area to timely and accurately predict the longwall progressive subsidence basin. However, the mainstream method that uses time function still has limitations, which impede extensive application. In this study, we analyzed the flaws of the optimized segmented Knothe time function in detail, and expounded the possible improvement directions. Subsequently, we proposed the Gompertz time function for predicting longwall progressive subsidence basin, based on the modeling idea that three origins are consistent. Afterward, we analyzed the variation law between parameters of the Gompertz time function and the geological mining conditions, and elaborated the parameter calculation method and the prediction algorithm for the longwall progressive subsidence basin. Finally, we demonstrated the practical application effect of this method with experiments. The average RMSE and average relative RMSE of predicted progressive subsidence using the Gompertz time function are 58.4 mm and 6.9%, respectively, and compared with the same statistics using the optimized segmented Knothe time function, the accuracy is increased by 27.9% on average. The results show that the accuracy of this article proposed method can achieve centimeter-level, meet the requirements of practical engineering application, and this method is expected to enable the mining proceeding in a safe, effective and environmentally sustainable way.

PurposeThis study aims to determine whether the stock holdings of equity mutual funds are informative for predicting future stock performance in the Chinese market. It is a puzzle that actively managed mutual funds underperform passive benchmarks, whereas retail investors still delegate investment decisions to the fund managers. The present study sheds light on whether mutual fund managers possess security selection skills in their top ten holdings.Design/methodology/approachBy regression analysis and portfolio sorting, this study focuses on 830 Chinese A-share stocks in the industry research reports from the Guotai Junan Securities Company. It collects mutual fund's top ten holdings data from the Wind Financial Terminal between 2019Q1 and 2021Q1. As robustness checks, the result holds for the fixed-effect model, an additional measure of ranks in the top ten holdings, the predictability test based on the confusion matrix and two stage least square (2SLS) regression.FindingsThe authors find that the top ten holdings by equity mutual funds are informative for predicting stock performance and can provide valuable information for investors to support their decision-making.Practical implicationsThe findings of this study provide insightful guidance for retail investors in making investment decisions and support the hypothesis that active fund management adds value.Originality/valueFirstly, the authors find that the top ten holdings of Chinese mutual funds show significantly positive signals for future stock excess returns, indicating the selection skills of fund managers. Secondly, the above positive relationship exhibits a diminishing marginal effect with more funds holding this stock. Thirdly, the authors find that the predictability horizon of the number of overweighing funds is up to three quarters and then diminishes in the fourth quarter. Finally, investors have a 59% prediction accuracy for the whole stock sample and an 85% precision conditional on the predicted positive subsample to outperform the market. The authors also address the endogeneity and reverse causality issues.

It is a challenge to map large-gradient deformation over mining areas via current InSAR (interferometric synthetic aperture radar) techniques. To this end, we present a new method that is combined ...

Pure copper (Cu) soldering joints with 304 stainless steel (SS) at different soldering temperatures (240–[Formula: see text]C) were prepared by using Sn–3.5 Ag (wt.%) as a soldering filler-metal material. The mechanical properties and microstructure evolution were investigated. Sound Cu/304 SS joints were obtained by soldering at 240–[Formula: see text]C for 90 s and the highest average joint shear strength was [Formula: see text] MPa when brazed at [Formula: see text]C. The Cu6Sn5 and Ag3Sn phases were typical intermetallic compounds (IMCs) in the joints at a soldering temperature of [Formula: see text]C. Cu3Sn IMCs were formed at the Cu/Cu6Sn5 interface as the soldering temperature increased to [Formula: see text]C and above. Shear fracture analysis by scanning electron microscopy (SEM) with energy dispersive spectroscopy showed that the joints fractured mostly inside the Cu6Sn5 layers.

Under the ravages of COVID-19, global supply chains have encountered unprecedented disruptions. Past experiences cannot fully explain the situations nor provide any suitable responses to these fatal shocks on supply chain management (SCM), especially in todays’ highly intertwined/globalized business environment. This research thus revisits and rechecks the crucial components for global SCM during such special periods, and the basic essence of such management covers numerous perspectives that can be categorized into a multiple criteria decision making (MCDM) approach. To handle this complex issue appropriately, one can introduce a fusion intelligent system that involves data envelopment analysis (DEA), rough set theory (RST), and MCDM to understand the reality of the analyzed problem in a faster and better manner. Based on the empirical results, we rank the priorities in order as cash management and information (D), raw material supply (B), global management strategy (C), and productivity and logistics (A) for improvement in SCM. This finding is confirmed by companies now undergoing a downsizing strategy in order to survive in this harsh business environment.

The drastic surface displacement and deformation caused by underground mining will have a serious impact on the ecological environment and the personal and property safety, although a broad range of backfill mining techniques has been applied to practical engineering, there is still a lack of effective methods to analyze the effects and laws of these techniques. In this paper, an analysis method for the effects of the mining technique of grouting into the overburden bedding separation (hereafter also referred to as the GOBS) is proposed, this method can be extended to other types of backfill mining techniques as well, and detailed analysis for a grouting mining district in Huaibei mining area, China was carried out by this method. Subsequently, the characteristics of surface subsidence and deformation (hereafter also referred to as the SSD) were summarized, and the relationship between six representative reduction rates of SSD and injection-extraction ratio were investigated, then the modeling verification and analysis were performed. Finally, the advantages and drawbacks of the mining technique of GOBS and other commonly used mining techniques for reduction SSD are compared. The results demonstrate that the mining technique of GOBS is of high cost-effectiveness to reduce the SSD, meanwhile, the reduction rates of SSD with injection-extraction ratio are subject to the Gompertz model very well, and consistent with actual situations. Therefore, they can be used for the design of grouting working faces and the prediction of SSD, and providing a scientific basis for guiding practical mining working in a safe, efficient and clean way.

The first total synthesis of laetispicine (1a), an amide alkaloid isolated from the stems of Piper laetispicum C.DC (Piperaceae), and the synthesis of some of its derivatives were described. Based on the evaluation of antidepressant activities in the forced swimming test, compounds 1h and 1i were identified as potent and safe antidepressant lead compounds.

The natural product Laetispicine ( N -isobutyl-(3,4-methylendioxyphenyl)-2E, 4E, 9E-undecatrienoamide), was isolated from the Piper laetispicum C. DC and screened, for its antidepressant activity and antinociceptive effects. Structure-functional activities of five natural products indicated that biological activity is dependent on double bonds present within the benzene ring and a conjugated double bond located at positions 2–3 and 4–5 in the molecular structure. To further understand the structural-activity relationship of Laetispicine as a new potent and safe antidepressant, the structural-activity relationship of 39 analogs of Laetispicine were synthetized and tested in forced swimming tests in mice whilst also in protective effects against glutamate or H 2 O 2 induced apoptosis in PC12 cells. The results show that the compound 30 — N -isobutyl-11-(4-chlorophenyl) undeca-2E,4E,9E-trienamide exhibited the same activity as the parental compound Laetispicine, and furthermore, the effective dose of this compound is lower than Laetispicine. Therefore, the compound 30 might be a potentially useful therapy in the treatment of depression. For structure, the conjugated double bonds located at 2-3, 4-5 and isolated double bonds from benzene ring are necessary for the antidepressant activities no matter the different length of carbon chain; the isobutyl connected with acylamino also are necessary; and the benzodioxole moiety is replaceable, the halogen atom in phenyl ring at the para-position could enhance this kind of activity.