Impact resistance performance and optimization of the sand-EPE composite cushion in rock sheds

Rock sheds are widely used to prevent rockfall disasters along roads in mountainous areas.To improve the capacity of rock sheds for resisting rockfall impact,a sand and expandable polyethylene(EPE)composite cushion was proposed.A series of model experiments of rockfall impact on rock sheds were conducted,and the buried depth of the EPE foam board in the sand layer was considered.The impact load and dynamic response of the rock shed were investigated.The results show that the maximum impact load and dynamic response of the rock shed roof are all significantly less than those of the sand cushion.Moreover,as the distance between the EPE foam board and rock shed roof decreases,the maximum rockfall impact force and impact pressure gradually decrease,and the maximum displacement,acceleration and strain of the rock shed first decrease and then change little.In addition,the vibration acceleration and vertical displacement of the rock shed roof decrease from the centre to the edge and decrease faster along the longitudinal direction than that along the transverse direction.In conclusion,the buffering effect of the sand-EPE composite cushion is better than that of the pure sand cushion,and the EPE foam board at a depth of 1/3 the thickness of the sand layer is appropriate.

SHEDS-PM模型模拟杭州市人群PM_(10)暴露水平

以杭州市为例,利用美国国家环境保护局(US EPA)国家暴露研究实验室(NERL)所开发的颗粒物人类暴露剂量随机模拟模型(SHEDS-PM),考察了人群在不同微环境中的PM10暴露水平.结合室外环境ρ(PM10)模拟结果、相关微环境参数和人群活动特征,对研究区域2004年不同季节室外环境、室内环境(住宅、办公室、学校、商店、餐馆)以及机动车内PM10暴露水平进行了模拟.结果表明:PM10暴露量、吸入量和沉积量与ρ(PM10)日均值呈正相关;1月PM10暴露量、吸入量和沉积量最大,分别为18.22,326.99和277.46μg/m3,三者在住宅环境中的剂量最大;不同微环境PM10平均沉积速率有明显差异.

Analysis of the Factors Influencing Breeding Record Establishment of Sheep-raising Households or Farms Based on Logit-ISM:Based on 849 Questionnaires from 17 Cities in Shandong Province

Breeding record is an important way to implement standardized sheep raising,trace major sheep raising epidemic information and ensure the quality and safety of products for sheep-raising households or farms.Based on 849 questionnaires from 17 cities of Shandong Province,the paper firstly used the binary discrete model of Logit to analyze the factors influencing the establishing behavior of breeding records of sheep-raising households or farms and then used the ISM model to explain the relationship and hierarchy of each influencing factor.The result showed that seven factors including the education level of the deciders,farming scale,fixed number of farming years,degree of specialization,support of the government,whether to join the industrialization organization and the recognition of the breeding records have a significant impact on the establishing behavior of breeding records of the sheep-raising households or farms.Among them,the support of the government and the recognition of breeding records are the surface direct factors,degree of specialization and whether to join the industrialization organization are the middle indirect factors,the education level of the deciders,the farming scale and the fixed number of farming years are deep source factors.

PbrARF4 contributes to calyx shedding of fruitlets in ‘Dangshan Suli’ pear by partly regulating the expression of abscission genes

Fruitlet calyx shedding in pear plants is apparently regulated via numerous pathways that involve both environmental triggers and phytohormones cues such as auxin. In this study, we found at 10 days after full bloom (DAFB) higher levels of indoleacetic acid (IAA) and tryptophan (Trp) in calyx persistence fruitlet (CPF) than calyx shedding fruitlet (CSF) ofDanshan Suli’ pear (Pyrus bretschneideri Rhed.). Consisting with this, the activity of indolealdehyde oxidase (IAAIdO), which promotes IAA synthesis, was remarkably increased, and that of peroxidase(POD), which degrades IAA, dropped markedly in CPF but not in CSF. Further, qRT-PCR results revealed that most of 31 PbrARFs (encoding auxin response factors) in Pyrus bretschneideri were highly expressed in CPF, whereas PbrARF4, PbrARF24 and PbrARF26 were significantly downregulated in CPF vis-a-vis CSF. Phylogenetic analysis revealed that 6 PbrARFs clustered in the group III, where PbrARF4 showed the closest affinity with AtARF1 that promotes organ abscission, indicating a putative role of PbrARF4 in mediating the process of calyx shedding in pear. In fact, the ectopic overexpression of PbrARF4 in Solanum lycopersicum resulted in an earlier-formed and deeper abscission layer (AL) in the transgenic plants, whose calyxes were more prone to wilt at the mature red stage (MR) compared with the control plants (wild-type). More importantly, expression levels of the abscission genes SILS and Sl Cel2 in transgenic plants overexpressing PbrARF4 were significantly upregulated in comparation with the WT, whereas those of Sl BI and Sl TAPG2 were considerably inhibited. Further, PbrJOINTLESS and PbrIDA,the two genes related to calyx shedding in pear, were up-regulated more in CSF than CPF. The findings contribute to a better understanding of PbrARFs involved in fruitlet calyx shedding of pear, which could prove beneficial to improving the quality of pear fruit.

Natural Ventilation by Air Captors and Extractors Sheds in Hospitals in Brazil： Wind Tunnel Measurements

Natural ventilation is an efficient design strategy for the passive cooling of buildings, especially in tropical countries such as Brazil. Among the ventilation strategies, sheds can be highlighted. These structures consist of roof openings that work as air captors or extractors depending on their location in relation to the prevailing wind directions. The hospitals of the Sarah Network, designed by the Brazilian architect Joao Filgueiras Lima, Lele, are worldwide known for using these elements to improve natural ventilation. This paper analyses the natural ventilation performance of sheds for air collecting and extracting in two Sarah hospitals located in the cities of Salvador and Rio de Janeiro. In each building, the sheds were analyzed for air extracting and collecting. The analyses were carried out by reduced physical models in an atmospheric boundary layer wind tunnel. The wind velocity was measured at external and internal points of the buildings, using hot-wire anemometers. The results show that the wards in Rio de Janeiro hospital are 17% more ventilated than the ones in the Salvador hospital. However, this difference occurs not only because of the collecting sheds but also because of set of openings and the configuration of the covering in hospitals in Rio de Janeiro.

Regulation of “Checkpoint Molecule” Sheds New Light on Anti-Cancer Drug Development

The rivalry between T cells and tumor cells somewhat mimics the scene of 'Tom and Jerry,' an animated series in which Tom (a house cat) rarely succeeds in catching Jerry (a mouse), mainly because of Jerry’s cleverness and cunning abilities. In a way, tumor cells are like Jerry, in terms of their crafty and sneaky features.

Coupled DEM-FDM analyses of the effects of falling rock’s shape and impact angle on response of granular cushion and rock shed

Rock shed is an effective protection measure against rockfall.To investigate the influences of falling rock’s shape and impact angle on the impact effect of the cushioned rock shed,a modeling approach for a rock shed with a cushion layer using PFC-FLAC.The granular cushion is modeled as an aggregate of discrete non-cohesion particles,while the concrete plate and the beam are modeled as zones.The falling rock with different sphericities and impact angles is modeled as a rigid assembly.The numerical model is validated by comparing the simulation results with experimental and numerical results from previous literature.This model is applied to analyze the effects of rock shape and impact angle on the dynamic interaction effects between falling rock and cushioned rock shed,including the impact force,transmitted bottom force,penetration depth,and plate deflection.The numerical results show that the variation in the falling rock’s shape has different effects on the falling rock with different impact angles.These findings could support rock shed design by revealing the limitations of the assumptions in the past research,which may result in unsafe rock sheds for some rockfall cases.

Relief Program Sheds Light on the Needy

EDITOR＇S NOTE： As the widening gap between the rich and poor has become a major byproduct of China＇s nonstop economic growth over the past decades, the improvement of the disadvantaged group＇s livelihood has become a top government concern. While numerous cities are working out their plans for ＂livelihood improvement projects,＂ local governments are making efforts to establish a sustainable mechanism that provides prompt, adequate relief to the needy. Licheng District in Jinan, capital of Shandong province, sets an example.

Load Profile Analysis for Mitigating Load-Shedding in Central Africa: Case of Kinshasa

Load shedding is a major problem in Central Africa, with negative consequences for both society and the economy. However, load profile analysis can help to alleviate this problem by providing valuable information about consumer demand. This information can be used by power utilities to forecast and reduce power cuts effectively. In this study, the direct method was used to create load profiles for residential feeders in Kinshasa. The results showed that load shedding on weekends results in significant financial losses and changes in people’s behavior. In November 2022 alone, load shedding was responsible for $ 23,4 08,984 and $ 2 80,9 07,808 for all year in losses. The study also found that the SAIDI index for the southern direction of the Kinshasa distribution network was 122.49 hours per feeder, on average. This means that each feeder experienced an average of 5 days of load shedding in November 2022. The SAIFI index was 20 interruptions per feeder, on average, and the CAIDI index was 6 hours, on average, before power was restored. This study also proposes ten strategies for the reduction of load shedding in the Kinshasa and central Africa power distribution network and for the improvement of its reliability, namely: Improved load forecasting, Improvement of the grid infrastructure, Scheduling of load shedding, Demand management programs, Energy efficiency initiatives, Distributed Generation, Automation and Monitoring of the Grid, Education and engagement of the consumer, Policy and regulatory assistance, and Updated load profile analysis.

植物激素对棉花蕾铃脱落的调控研究进展

棉花蕾铃脱落是一个普遍存在的现象,有对逆境环境胁迫的主动适应性脱落,也有因品种遗传特性、环境条件、栽培措施以及生物和非生物胁迫被动的受损脱落。蕾铃脱落直接影响着棉花的产量,国内外现有公开报道多集中于20世纪50、60年代关于乙烯和脱落酸对棉花蕾铃脱落影响的初步发现。结合其他植物的研究结果来看,蕾铃脱落似乎与生长素、赤霉素和细胞分裂素等促生长类激素的下降以及乙烯和脱落酸等抑制生长类激素的升高密切相关,激素在植物体内不仅介导新陈代谢过程,还协调着与信号通路相关的调控因子,在脱落过程中起着关键作用。本文从植物激素调控入手,综述了近年来包括脱落区形成和作用的分子调控机制以及各激素在棉花蕾铃脱落以及其他植物(生殖)器官脱落过程中的响应和调控机制等。发现目前以棉花蕾铃脱落为对象的研究非常匮乏,且多集中于少数激素对棉花生殖生长影响的有限研究,缺乏对导致蕾铃脱落的深层次机制的探究和解析。因此,未来研究方向应着重于探究棉花蕾铃脱落的遗传基础、发掘新的抗脱落基因资源和培育抗脱落棉花品种,同时加强在以棉花为模型植物下,蕾铃脱落与植物激素调节的关系研究,为提高棉花产量提供理论依据和技术支持。

Design and Construction of Removable DeepLitter Breeding Shed

The pig-on-litter system is characterized by reduced environmental pollution and high-quality pork. It has won the support of the government and the acceptance of market. It is urgent to develop the supporting facilities and products to promote the comprehensive promotion of this technology. Based on the climatic and hydro- logical conditions in Jiangsu Province, we designed the removable deep-litter breed- ing shed. Its construction costs were lower than that of ordinary water-flushed pig- gery. In addition, this breeding system would not consolidate the land. The indoor ventilation and heat-conservation performances also met the requirements by pig-on- litter system. The removable shed can be promoted as an important supporting technology for the deep-litter breeding model in the eastern China.

Effects of Different Upland Seedling Nurturing Modes on Shed Temperature and Rice Seedling Quality

In order to compare the advantages and disadvantages of large-shed,middle-shed and small-shed upland seedling nurturing modes in japonica rice planting regions of North China, in this study, Tongyin 58, Tonghe 836 and Tonghe 835 were used as experimental materials and cultivated with large-shed, middle-shed and small-shed upland seedling nurturing modes to investigate active and effective accumulated temperature and rice seedling quality. According to the results, active and effective accumulated temperature in three different upland seedling nurturing treatments during seedling nurturing period were generally in a descending order of large shed 〉 middle shed 〉 small shed. The occurrence frequency of temperature exceeding the biological upper limit for rice growth in different upland seedling nurturing treatments demonstrated a descending order of large shed 〉 small shed 〉middle shed; the occurrence frequency of temperature below the biological lower limit demonstrated a descending order of small shed 〉 middle shed 〉 large shed.Plant height, root number, aboveground dry weight, underground dry weight and emergence rate varied significantly among different upland seedling nurturing modes,which showed a descending order of large shed 〉 middle shed 〉 small shed; leaf age and stem number in large shed was significantly higher than that in middle and small sheds, but there was no significant difference in leaf age and stem number between middle and small sheds; underground dry weight varied slightly between large and middle shed, but underground dry weight in large and middle shed was remarkably higher than that in small shed. In production, large-shed upland seedling nurturing is most appropriate technique, followed by middle-shed upland seedling nurturing. In large-shed upland seedling nurturing, ventilation and seedling hardening should be strengthened. Small-shed upland seedling nurturing technique is not recommended to be used in regions with low accumulated temperature at night. In small-shed upland seedling nurturing, the minimum temperature at night should be concerned, and heat preservation measures should be taken immediately when there is a sudden drop in temperature.

Therapeutic targeting of cellular prion protein: toward the development of dual mechanism anti-prion compounds

PrPSc,a misfolded,aggregation-prone isoform of the cellular prion protein(PrPC),is the infectious prion agent responsible for fatal neurodegenerative diseases of humans and other mammals.PrPSccan adopt different pathogenic conformations(prion strains),which can be resistant to potential drugs,or acquire drug resistance,posing challenges for the development of effective therapies.Since PrPCis the obligate precursor of any prion strain and serves as the mediator of prion neurotoxicity,it represents an attractive therapeutic target fo r prion diseases.In this minireview,we briefly outline the approaches to target PrPCand discuss our recent identification of Zn(Ⅱ)-Bn PyP,a PrPC-targeting porphyrin with an unprecedented bimodal mechanism of action.We argue that in-depth understanding of the molecular mechanism by which Zn(Ⅱ)-Bn PyP targets PrPCmay lead toward the development of a new class of dual mechanism anti-prion compounds.

基于粘合棚杆地膜的小拱棚铺膜机的设计与实验

旨在为小拱棚铺膜机的研发提供了一种新的研究方向与思路。设计时,使用一种带棚杆的复合地膜,即将棚杆按一定间隔事先粘接在地膜上,制作成一种特殊的地膜。这种地膜在铺膜机鸭嘴式拱形模具的压制下,将棚杆与地膜一起从鸭嘴式拱形模具中拉出并压入地膜两边开好的沟槽中,再经覆土、压实,完成小拱棚铺设工作。这种铺设方法的优点是铺设机械设备简单、价格低、铺设过程中棚杆的间距恒定、棚杆与地膜入土深度稳定、铺设过程能实现连续高效作业、铺设质量稳定,且操作简单、安全可靠;缺点是地膜与铺膜机必需是专用的、通用性差。

二氢杨梅素对SHED活性及其成骨分化能力的影响

目的探讨二氢杨梅素(DMY)对人乳牙牙髓干细胞(SHED)活性及成骨分化能力的影响。方法体外分离培养鉴定SHED,分别检测不同浓度的DMY对SHED的细胞活性、碱性磷酸酶(ALP)活性以及成骨相关基因Runt相关转录因子2(Runx2)和骨钙素(OCN) mRNA的表达的影响。结果 CCK-8检测结果显示,与对照组比较,0. 02、0. 1、0. 5、2、10及50μmol/L浓度的DMY对SHED的增殖能力差异无统计学意义;10、50μmol/L浓度的DMY ALP活性较对照组高(P <0. 05),0. 1、0. 5、2、10及50μmol/L DMY组的Runx2及0. 5、2、10、50μmol/L DMY组OCN成骨诱导前后相对倍增数均高于对照组(P <0. 05),并呈现一定的浓度依赖性。结论 0. 02、0. 1、0. 5、2、10及50μmol/L的(DMY)对SHED活性无明显影响,一定浓度的DMY可促进SHED成骨分化的能力。

巷道高空作业机构的设计与模态分析

介绍了巷道架棚设备所用的高空作业机构的结构及其在使用过程中的受力状态,通过对2种工况的静力学分析得出了高空作业机构最恶劣的受力状态。最后对四级伸缩机械臂做了8阶模态分析,验证了四级伸缩机械臂不会与整机发生共振现象,为整机结构设计提供了部分理论基础。

Effect of perforation on flow past a conic cylinder at Re=100:vortex-shedding pattern and force history

The flow past a circular-section cylinder with a conic shroud perforated with four holes at the peak was simulated numerically at Re = 100, considering two factors, viz.the angle of attack and the diameter of the holes. The effects of the perforated conic shroud on the vortex shedding pattern in the near wake was mainly investigated, as well as the time history of the drag and lift forces. In the investigated parameter space, three flow regimes were generally identified, corresponding to weak, moderate, and strong disturbance effects.In regime I, the wake can mainly be described by alternately shedding Kármán or Kármán-like vortices. In regime II, the spanwise vortices are obviously disturbed along the span due to the appearance of additional vorticity components and their interactions with the spanwise vortices, but still shed in synchronization along the spanwise direction. In regime III,the typical Kármán vortices partially or totally disappear,and some new vortex shedding patterns appear, such as-type, obliquely shedding, and crossed spanwise vortices with opposite sign. Corresponding to these complex vortex shedding patterns in the near wake, the fluid forces no longer oscillate regularly at a single vortex shedding frequency, but rather with a lower modulation frequency and multiple amplitudes. An overview of these flow regimes is presented.

Dynamic response and optimization of an inclined steel rock shed by the graded energy dissipating method

Blocking rockfalls directly by reinforced concrete(RC) flat sheds with thick sand cushions is an outdated method. Such conventional sheds typically accumulate rock heavily, and become progressively damaged and are difficult to repair, and are very costly. To address these problems, we propose a new structure called a Graded Dissipating Inclined Steel Rock(GDISR) shed that utilizes the graded energy dissipation method. Here, we study the dynamic response of the GDISR shed with model test and numerical simulation, and give its optimization design combining with a practical engineering case. Our results show that the optimized modular E-block and corrugated steel tube can deform to sufficiently absorb the energy of different impact intensities. This efficiently and economically provides GDISR sheds with two security lines. Compared with conventional RC sheds, GDISR sheds with optimal incline have a more efficient anti-impact function, are faster and easier to repair, and are much simpler and cheaper to build.