Low-temperature characteristicsof rubbers and performance testsof type 120 emergencyvalve diaphragms

Purpose–The type 120 emergency valve is an essential braking component of railway freight trains,butcorresponding diaphragms consisting of natural rubber(NR)and chloroprene rubber(CR)exhibit insufficientaging resistance and low-temperature resistance,respectively.In order to develop type 120 emergency valverubber diaphragms with long-life and high-performance,low-temperatureresistant CR and NR were processed.Design/methodology/approach–The physical properties of the low-temperature-resistant CR and NRwere tested by low-temperature stretching,dynamic mechanical analysis,differential scanning calorimetryand thermogravimetric analysis.Single-valve and single-vehicle tests of type 120 emergency valves werecarried out for emergency diaphragms consisting of NR and CR.Findings–The low-temperature-resistant CR and NR exhibited excellent physical properties.The elasticityand low-temperature resistance of NR were superior to those of CR,whereas the mechanical properties of thetwo rubbers were similar in the temperature range of 0℃–150℃.The NR and CR emergency diaphragms metthe requirements of the single-valve test.In the low-temperature single-vehicle test,only the low-temperaturesensitivity test of the NR emergency diaphragm met the requirements.Originality/value–The innovation of this study is that it provides valuable data and experience for futuredevelopment of type 120 valve rubber diaphragms.

企业遗产对持续竞争优势的影响研究:品牌资产的中介作用和动态能力的调节作用

本文拓展资源与机会互动的资源基础观,研究成熟期企业利用遗产资源创造品牌竞争力进而保持竞争优势的过程,分析动态能力不同的企业其遗产对品牌资产和持续竞争优势的影响差异。利用来自208家"中华老字号"企业的问卷调查数据对理论模型进行了实证检验。研究发现,成熟期企业的文化遗产、创业精神、专有知识能够正向影响企业品牌资产,并通过品牌资产的中介作用正向影响企业的持续竞争优势。对于动态能力强的企业,传统创业精神对品牌资产的影响会被削弱,但专业知识的使用和保护对品牌资产的影响会增强。成熟期企业需要辨识自身以战略网络掌控和动态竞争能力为代表的动态能力的强弱,进而确定自身的企业遗产应用战略。

Experimental study of the gap between track slab and cement asphalt mortar layer in CRTS I slab track

Gap exists in the interface of cement asphalt emulsion mortar and CRTS I track slab universally, which is more severe at four corners than other parts of the track slab. In this work, the temperature and elevation of CRTS I slab track with and without rail were measured continuously to study the influence mechanism of rail on the gap. The results show that the alternating temperature gradient of track slab is the main reason that causes the gap, and laying rail can efficiently decrease the gap size in the slab track without rail. Compared with the slab track without rail, the maximum elevation occurred at the corner, the maximum gapwidth and the maximum gap depth of the slab track with rail laid were decreased by 0.45 mm （25.7%）, 0.75 mm （46.6%） and 9.5 mm （59.4%）, respectively; meanwhile, the disqualification ratio at corners was reduced to 5.9%, which is 50% less than that of the track without rail. When elevation mismatch occurs in adjacent track slabs, a gasket should be placed at rail-bearing bed below the track slab in order to avoid the lower slab being dragged up by the higher slab and the further occurrence of new gap.

A study of flames with millimeter-wave radiation

It is a valuable issue to explore whether a flame can radiate microwaves,in spite of the electric field formed in the flame.Presented herein is an experimental study on a series of flames with millimeterwave radiation in the combustion of pyrotechnic films.The pyrotechnic films were composed of ultrafine red phosphorus(P),sodium nitrate(NaNO_3),Polyvinyl Alcohol(PVA) and some additives such as chopped carbon fibers(CFs) and aluminized glass fibers(GFs).The combustion temperatures and millimeter-wave radiation signals of the flames were measured,the millimeter-wave emissivity and spectral radiant exitance were calculated to describe the millimeter-wave radiation intensity.The results demonstrate that the flame of the pyrotechnic films based on P/NaNO_3/CFs can radiate millimeter waves,and different materials and their proportion have a great effect on the millimeter-wave radiation intensity.

Exosomes derived from BMSCs ameliorate cyclophosphamide-induced testosterone deficiency by enhancing the autophagy of Leydig cells via the AMPK-mTOR signaling pathway

Cyclophosphamide-induced testosterone deficiency (CPTD) during the treatment of cancers and autoimmune disorders severelyinfluences the quality of life of patients. Currently, several guidelines recommend patients suffering from CPTD receive testosteronereplacement therapy (TRT). However, TRT has many disadvantages underscoring the requirement for alternative, nontoxictreatment strategies. We previously reported bone marrow mesenchymal stem cells-derived exosomes (BMSCs-exos) could alleviatecyclophosphamide (CP)-induced spermatogenesis dysfunction, highlighting their role in the treatment of male reproductive disorders.Therefore, we further investigated whether BMSCs-exos affect autophagy and testosterone synthesis in Leydig cells (LCs). Here,we examined the effects and probed the molecular mechanisms of BMSCs-exos on CPTD in vivo and in vitro by detecting theexpression levels of genes and proteins related to autophagy and testosterone synthesis. Furthermore, the testosterone concentrationin serum and cell-conditioned medium, and the photophosphorylation protein levels of adenosine monophosphate-activatedprotein kinase (AMPK) and mammalian target of rapamycin (mTOR) were measured. Our results suggest that BMSCs-exos couldbe absorbed by LCs through the blood–testis barrier in mice, promoting autophagy in LCs and improving the CP-induced low serumtestosterone levels. BMSCs-exos inhibited cell death in CP-exposed LCs, regulated the AMPK-mTOR signaling pathway to promoteautophagy in LCs, and then improved the low testosterone synthesis ability of CP-induced LCs. Moreover, the autophagy inhibitor,3-methyladenine (3-MA), significantly reversed the therapeutic effects of BMSCs-exos. These findings suggest that BMSCs-exospromote LC autophagy by regulating the AMPK-mTOR signaling pathway, thereby ameliorating CPTD. This study provides novelevidence for the clinical improvement of CPTD using BMSCs-exos.

Self-healing polyamide reverse osmosis membranes with temperature-responsive intelligent nanocontainers for chlorine resistance

Improving the performance of reverse osmosis membranes remains great challenge to ensure excellent NaCl rejection while maintaining high water permeability and chlorine resistance. Herein, temperature-responsive intelligent nanocontainers are designed and constructed to improve water permeability and chlorine resistance of polyamide membranes. The nanocontainer is synthesized by layer-by-layer self-assembly with silver nanoparticles as the core, sodium alginate and chitosan as the repair materials, and polyvinyl alcohol as the shell. When the polyamide layer is damaged by chlorine attack, the polyvinyl alcohol shell layer dissolves under temperature stimulation of 37 ℃, releasing inner sodium alginate and chitosan to repair broken amide bonds. The polyvinyl alcohol shell responds to temperature in line with actual operating environment, which can effectively synchronize the chlorination of membranes with temperature response and release inner materials to achieve self-healing properties. With adding temperature-responsive intelligent nanocontainers, the NaCl rejection of thin film composite membrane decreased by 15.64%, while that of thin film nanocomposite membrane decreased by only 8.35% after 9 chlorination cycles. Effective repair treatment and outstanding chlorine resistance as well as satisfactory stability suggest that temperature-responsive intelligent nanocontainer has great potential as membrane-doping material for the targeted repair of polyamide reverse osmosis membranes.

Gold nanorod translocation through a solid-state nanopore

Recently,nanopores have been used in an essential technique for detecting single molecule with high sensitivity.The initial application of nanopores to DNA and RNA sequencing has been expanded to sensing proteins and nanoparticles,including Bovine serum albumin,silica nanoparticles,polystyrene beads,and others.In our study,for the first time,a positively charged gold nanorod was investigated using a solid-state nanopore device.Various gold nanorods passed through the nanopore with different current blockages and duration times,providing a measurement of the nanorod diameter,length,and charge.Our findings indicate that nanopore sensing might be a new method for characterizing the size,shape,and charge of nanoparticles.

Kicking down the ladder： adding cleavable features to genetically encoded photocrosslinkers

Protein-protein interactions(PPIs)play vital roles in biological processes.However,the discovery of transient and biologically relevant PPIs remain a formidable challenge using conventional strategies such as co-immunoprecipitation(CoIP),yeast two hybrids(Y2H)and Forster resonance energy transfer(FRET)[1].Genetically encoded photocrosslinkers have recently emerged as a powerful approach for probing intracellular PPIs with the capability for in situ studies,low perturbation to cells as well as the wide generality.This facile strategy also demonstrated an advantage of high spatiotemporal resolution,which offers a robust capture strategy for the discovery of transient and/or weak PPIs with lowered false-positive backgrounds[2].

BeXplorer:Visual analytics of dynamic interplay between communication and purchase behaviors in MMORPGs

With the rapid development of massively multiplayer online role-playing games(MMORPGs),a huge amount of fine-grained data on the in-game activities of players have been recorded by MMORPGs operators.These data provide considerable opportunities with which to study the dynamic interplay between player behaviors and investigate the roles of various social structures that underlie such interplay.However,it is challenging to model and visualize these behavioral data.This study proposes a novel influence-susceptible model to measure the dynamic interplay between behaviors.Based on this model,we introduce a new visual analytics system called BeXplorer.This system enables analysts to interactively explore the dynamic interplay between player purchase and communication behaviors and to examine the manner in which this interplay is bound by social structures where players are embedded.Three case studies and a task-based evaluation are conducted to demonstrate the effectiveness and applicability of our method.