Ground response to high horizontal stresses during longwall retreat and its implications for longwall headgate support

Roof falls in longwall headgate can occur when weak roof and high horizontal stress are present. To prevent roof falls in the headgate under high horizontal stress, it is important to understand the ground response to high horizontal stress in the longwall headgate and the requirements for supplemental roof support. In this study, a longwall headgate under high horizontal stress was instrumented to monitor stress change in the pillars, deformations in the roof, and load in the cable bolts. The conditions in the headgate were monitored for about six months as the longwall face passed by the instrumented site.The roof behavior in the headgate near the face was carefully observed during longwall retreat.Numerical modeling was performed to correlate the modeling results with underground observation and instrumentation data and to quantify the effect of high horizontal stress on roof stability in the longwall headgate. This paper discusses roof support requirements in the longwall headgate under high horizontal stress in regard to the pattern of supplemental cable bolts and the critical locations where additional supplemental support is necessary.

Heat shock protein 47 promotes tumor survival and therapy resistance by modulating AKT signaling via PHLPP1 in colorectal cancer

Objective:Heat shock protein 47(HSP47)is a collagen-specific molecular chaperone that facilitates collagen maturation.Its role in cancer remains largely unknown.In this study,we investigated the roles o f HSP47 in colorectal cancer(CRC)and therapy resistance.Methods:Expression o f HSP47 in CRC tissues was examined(1)in paired human CRC/adjacent normal tissues,using real time quantitative reverse transcription polymerase chain reaction(qRT-PCR),The Cancer Genome Atlas(TCGA)database,and 22 independent m icroarray databases(curated CRC).In vitro studies on several CRC cell lines(H C T 116,RKO and C C L228)with modulated HSP47 expression were conducted to assess cell viability and apoptosis(TU N EL assay and caspase-3/-7)during exposure to chemotherapy.AKT signaling and co-imm unoprecipitation studies were performed to examine HSP47 and PHLPP1 interaction.In vivo studies using tumor xenografts were conducted to assess the effects of HSP47 modulation on tum or growth and therapy response.Results:HSP47 was upregulated in CRC and was associated with poor prognosis in individuals with CRC.In vitro,HSP47 overexpression supported the survival of CRC cells,whereas its knockdown sensitized cells to 5-fluorouracil(5-FU).HSP47 promoted survival by inhibiting apoptosis,enhancing AKT phosphorylation,and decreasing expression of the AKT-specific phosphatase PHLPP1 when cells were exposed to chemotherapy.These effects were partly results of the interaction between HSP47 and PHLPP1,which decreased PHLPP1 stability and led to more persistent AKT activity.In vivoy HSP47 supported tumor growth despite 5-FU treatment.Conclusions:HSP47 supports the growth of CRC tumors and suppresses the efficacy of chemotherapy via modulation of AKT signaling.

Influence of longwall mining on the stability of gas wells in chain pillars

Longwall mining has a significant influence on gas wells located within longwall chain pillars.Subsurface subsidence and abutment pressure induced by longwall mining can cause excessive stresses and deformations in gas well casings.If the gas well casings are compromised or ruptured,natural gas could migrate into the mine workings,potentially causing a fire or explosion.By the current safety regulations,the gas wells in the chain pillars have to be either plugged or protected by adequate coal pillars.The current regulations for gas well pillar design are based on the 1957 Pennsylvania gas well pillar study.The study provided guidelines for gas well pillars by considering their support area and overburden depth as well as the location of the gas wells within the pillars.As the guidelines were developed for room-andpillar mining under shallow cover,they are no longer applicable to modern longwall coal mining,particularly,under deep cover.Gas well casing of failures have occurred even though the chain pillars for the gas wells met the requirements by the 1957 study.This study,conducted by the National Institute for Occupational Safety and Health(NIOSH),presents seven cases of conventional gas wells penetrating through longwall chain pillars in the Pittsburgh Coal Seam.The study results indicate that overburden depth and pillar size are not the only determining factors for gas well stability.The other important factors include subsurface ground movement,overburden geology,weak floor,as well as the type of the construction of gas wells.Numerical modeling was used to model abutment pressure,subsurface deformations,and the response of gas well casings.The study demonstrated that numerical models are able to predict with reasonable accuracy the subsurface deformations in the overburden above,within,and below the chain pillars,and the potential location and modes of gas well failures,thereby providing a more quantifiable approach to assess the stability of the gas wells in longwall chain pillars.

Geotechnical considerations for concurrent pillar recovery in close-distance multiple seams

Room-and-pillar mining with pillar recovery has historically been associated with more than 25% of all ground fall fatalities in underground coal mines in the United States.The risk of ground falls during pillar recovery increases in multiple-seam mining conditions.The hazards associated with pillar recovery in multiple-seam mining include roof cutters, roof falls, rib rolls, coal outbursts, and floor heave.When pillar recovery is planned in multiple seams, it is critical to properly design the mining sequence and panel layout to minimize potential seam interaction.This paper addresses geotechnical considerations for concurrent pillar recovery in two coal seams with 21 m of interburden under about 305 m of depth of cover.The study finds that, for interburden thickness of 21 m, the multiple-seam mining influence zone in the lower seam is directly under the barrier pillar within about 30 m from the gob edge of the upper seam.The peak stress in the interburden transfers down at an angle of approximately 20°away from the gob, and the entries and crosscuts in the influence zone are subjected to elevated stress during development and retreat.The study also suggests that, for full pillar recovery in close-distance multiple-seam scenarios,it is optimal to superimpose the gobs in both seams, but it is not necessary to superimpose the pillars.If the entries and/or crosscuts in the lower seam are developed outside the gob line of the upper seam,additional roof and rib support needs to be considered to account for the elevated stress in the multiple-seam influence zone.

Effect of longwall-induced subsurface deformations on shale gas well casing stability under deep covers

This paper presents the results of a 2017 study conducted by the National Institute for Occupational Safety and Health(NIOSH), Pittsburgh Mining Research Division(PMRD), to evaluate the effects of longwall-induced subsurface deformations within a longwall abutment pillar under deep cover. The 2017 study was conducted in a southwestern Pennsylvania coal mine, which extracts 457 m-wide longwall panels under 361 m of cover. One 198 m-deep, in-place inclinometer monitoring well was drilled and installed over a 45 m by 84 m center abutment pillar. In addition to the monitoring well, surface subsidence measurements and underground coal pillar pressure measurements were conducted as the 457 m-wide longwall panel on the south side of the abutment pillar was being mined. Prior to the first longwall excavation, a number of simulations using FLAC3D^(TM) were conducted to estimate surface subsidence, increases in underground coal pillar pressure, and subsurface horizontal displacements in the monitoring well. Comparisons of the pre-mining FLAC3D simulation results and the surface, subsurface,and underground instrumentation results show that the measured in-place inclinometer casing deformations are in reasonable agreement with those predicted by the 3D finite difference models. The measured surface subsidence and pillar pressure are in excellent agreement with those predicted by the 3D models.Results from this 2017 research clearly indicate that, under deep cover, the measured horizontal displacements within the abutment pillar are approximately one order of magnitude smaller than those measured in a 2014 study under medium cover.

Empirical Study on the Benefit Increase of New Contract Farming 1+3+X Model

For a long time,the development model of traditional rice planting industry has been single,linear,and focusing on production first and then market.However,with the low price of rice,such problems as slow technological upgrading,meager profits,and unstable rice quality in the primary industry planting units and farmers have become increasingly prominent.The integration and development of the rural primary,secondary,and tertiary industries and industrial integration have the same root.They are integrated industrial development based on technological or model innovation,vertical and horizontal integration.Three agricultural leading companies(Nanjing Tianwei Agricultural Technology Co.,Ltd.,Nanjing CHYKINGYOUNG Biological Technology Co.,Ltd.,and Jiangsu Jingshan Eco-organic Agriculture Co.,Ltd.)established an industrialization complex,and used their respective technical,operational,and market advantages to integrate and form a rice contract farming 1+3+X model.This model effectively integrates scattered rice planting,rice processing,and rice sales in Nanjing City of Jiangsu Province,and Chuzhou City of Anhui Province,and unifies planting regulations and supply of production materials,safeguards the supply of green and high-quality rice and realizes high quality and high price.In addition,it integrates farmers into the entire industrial chain of contract farming,summons up the production enthusiasm of farmers and greatly increases their income from planting production.

道禅著作中的气和虚:与西方活力论思想的比较

受负熵冲动的驱使,本文在中国传统的气论和阴阳理论与柏格森的生命冲动概念及德勒兹的虚在和实在概念之间建立了对话。文章表明道家的精神修炼和禅宗的内观关涉到对柏格森式的分化或创造性演化的逆转。言下之意,道教和禅宗重虚在而轻实在、重形变能力而轻形。道教所谓的返老还童和禅宗所谓的觉悟的实质即在于此。文章认为虚拟二重体的存在使得“事物”有精气神。通过援引《易经》背后的推理,文章表明过度技术化势必带来精神贫瘠,我们这个时代的精神修炼应该帮助解决技术所造成的精神匮乏问题。

The current perspective of the PA 1957 gas well pillar study and its implications for longwall gas well pillars

Many states rely upon the Pennsylvania 1957 Gas Well Pillar Study to evaluate the coal barrier surrounding gas wells.The study included 77 gas well failure cases that occurred in the Pittsburgh and Freeport coal seams over a 25-year span.At the time,coal was mined using the room-and-pillar mining method with full or partial pillar recovery,and square or rectangle pillars surrounding the gas wells were left to protect the wells.The study provided guidelines for pillar sizes under different overburden depths up to 213 m(700 ft).The 1957 study has also been used to determine gas well pillar sizes in longwall mines since longwall mining began in the 1970 s.The original study was developed for room-and-pillar mining and could be applied to gas wells in longwall chain pillars under shallow cover.However,under deep cover,severe deformations in gas wells have occurred in longwall chain pillars.Presently,with a better understanding of coal pillar mechanics,new insight into subsidence movements induced by retreat mining,and advances in numerical modeling,it has become both critically important and feasible to evaluate the adequacy of the 1957 study for longwall gas well pillars.In this paper,the data from the 1957 study is analyzed from a new perspective by considering various factors,including overburden depth,failure location,failure time,pillar safety factor(SF),and floor pressure.The pillar SF and floor pressure are calculated by considering abutment pressure induced by full pillar recovery.A statistical analysis is performed to find correlations between various factors and helps identify the most significant factors for the stability of gas wells influenced by retreat mining.Through analyzing the data from the 1957 study,the guidelines for gas well pillars in the 1957 study are evaluated for their adequacy for roomand-pillar mining and their applicability to longwall mining.Numerical modeling is used to model the stability of gas wells by quantifying the mining-induced stresses in gas well casings.Results of this study indicate that the guidelines in the 1957 study may be appropriate for pillars protecting conventional gas wells in both room-and-pillar mining and longwall mining under overburden depths up to 213m(700 ft),but may not be sufficient for protective pillars under deep cover.The current evaluation of the 1957 study provides not only insights about potential gas well failures caused by retreat mining but also implications for what critical considerations should be taken into account to protect gas wells in longwall mining.

Distinct Subcellular Localization of GSK-3<i>β</i>in Melanocytic Nevi: Implications in Melanocyte Senescence

Melanocytic nevi are a transient in vivo proliferation of melanocytes that after time undergo cellular senescence. Most nevi harbor B-Raf mutations, which appear to activate cellular mechanisms of senescence in melanocytes. Glycogen synthase kinase 3β (GSK-3β), a critical downstream effector of the AKT signaling pathway, is involved in the development of melanoma and has been associated with senescence in melanocytes. Our immunohistochemical and immunofluorescence studies revealed distinct, perinuclear, dot-like reactivity of GSK-3β in melanocytic nevi. Furthermore, our tissue microarray analysis demonstrated significant perinuclear dot-like sublocalization of GSK-3β in melanocytic nevi compared with the amount of GSK-3β observed in melanoma (P β in human nevi may contribute to senescence in melanocytes.