椰棕基硬质聚氨酯泡沫的制备及其性能

利用微波辅助液化技术将椰棕粉末进行液化制得液化物,以液化物为原料、三乙烯二胺(TEDA)和异辛酸锡(TECH)为复合催化剂、水为发泡剂,与多苯基甲烷多异氰酸酯反应通过一步法制备了硬质聚氨酯泡沫(PURF)。对水发泡制备PURF的条件进行优化,较优的制备条件为催化剂中TEDA和TECH的质量比为4:5、催化剂质量分数为5%、泡沫稳定剂M-8818质量分数为2.5%、发泡剂质量分数为2%,该条件下制备的PURF的压缩强度为223 kPa,超过了大部分生物基PURF。采用傅里叶变换红外光谱对液化物、液化剂和PURF进行表征,通过扫描电镜对泡沫泡孔进行观察。结果显示,所合成的PURF大部分为闭孔,体系中基本没有异氰酸根剩余。使用锥形量热仪对最优PURF进行燃烧行为分析,最大热释放速率(HRR)为250.6 kW/m^(2)。

The effect of slow shot speed and casting pressure on the 3D microstructure of high pressure die casting AE44 magnesium alloy

3D reconstruction and 2D observation were conducted to characterize the microstructure of the castings produced through high pressure die casting with different parameters.Our results indicate that shrinkage pores generally co-existed with externally solidified crystals(ESCs).In specimen produced without fast slow shot speed,big net-shrinkage pores accompanied with ESCs were found in the center of the specimen.When the casting pressurization was introduced,the shrinkage pores gathered to the specimen center and became much less due to the optimization of melt feeding.Much more porosity was found near the gate rather than in the middle of the rod bar,especially gas pores.Thefilling process simulation reveals that the middle position of the bars wasfirstlyfilled and followed by the near gate position accompanied with one intense turbulentflow.

Carbon emissions reduction potentiality for railroad transportation based on life cycle assessment

This study addresses the comparative carbon emissions of different transportation modes within a unified evaluation framework,focusing on their carbon footprints from inception to disposal.Specifically,the entire life cycle carbon emissions of High-Speed Rail(HSR),battery electric vehicles,conventional internal combustion engine vehicles,battery electric buses,and conventional internal combustion engine buses are analyzed.The life cycle is segmented into vehicle manufacturing,fuel or electricity production,operational,and dismantlingrecycling stages.This analysis is applied to the Beijing-Tianjin intercity transportation system to explore emission reduction strategies.Results indicate that HSR demonstrates significant carbon emission reduction,with an intensity of only 24%-32% compared to private vehicles and 47%-89% compared to buses.Notably,HSR travel for Beijing-Tianjin intercity emits only 24% of private vehicle emissions,demonstrating the emission reduction benefits of transportation structure optimization.Additionally,predictive modeling reveals the potential for carbon emission reduction through energy structure optimization,providing a guideline for the development of effective transportation management systems.

脂肪族缩水甘油醚的制备与性能及其在轻质材料中的应用

以C_(12-14)醇与环氧乙烷、环氧氯丙烷等为原料,合成了低凝固点乙二醇C_(12-14)烷基醚缩水甘油醚(EGAGE),其环氧值为0.28 mol/100 g、25℃时黏度为14 mPa·s、凝固点为-6.9℃,利用红外光谱和核磁共振氢谱对产物结构进行了表征。将EGAGE与市售活性稀释剂C_(12-14)烷基缩水甘油醚(AGE)进行了详细的对比分析,分别考察了二者的基本性能指标对双酚A型环氧树脂(DGEBA)的降黏效果、固化物的力学性能、热稳定性和耐化学性及对环氧树脂泡沫性能的影响。力学性能测试表明,与纯DGEBA相比,含10%EGAGE的DGEBA,其固化物的弯曲强度、冲击强度和断裂伸长率分别提升了11%,72%和16%。扫描电镜分析表明,EGAGE/DGEBA的断裂方式为韧性断裂,增韧效果良好。热失重和耐化学性分析结果表明,EGAGE/DGEBA的热稳定性更好、耐化学性更优。加入EGAGE的环氧泡沫(EGAGE/ESF)密度为0.798 g/cm^(3)、比强度达到102.41 N·m/kg,EGAGE/ESF具有密度小、吸水率低和比强度高的优点,在轻质复合材料领域中具有极大的应用潜力。

A power plant for integrated waste energy recovery from liquid air energy storage and liquefied natural gas

Liquefied natural gas(LNG)is regarded as one of the cleanest fossil fuel and has experienced significant developments in recent years.The liquefaction process of natural gas is energy-intensive,while the regasification of LNG gives out a huge amount of waste energy since plenty of high grade cold energy(-160℃)from LNG is released to sea water directly in most cases,and also sometimes LNG is burned for regasification.On the other hand,liquid air energy storage(LAES)is an emerging energy storage technology for applications such as peak load shifting of power grids,which generates 30%-40%of compression heat(-200℃).Such heat could lead to energy waste if not recovered and used.The recovery of the compression heat is technically feasible but requires additional capital investment,which may not always be economically attractive.Therefore,we propose a power plant for recovering the waste cryogenic energy from LNG regasification and compression heat from the LAES.The challenge for such a power plant is the wide working temperature range between the low-temperature exergy source(-160℃)and heat source(-200℃).Nitrogen and argon are proposed as the working fluids to address the challenge.Thermodynamic analyses are carried out and the results show that the power plant could achieve a thermal efficiency of 27%and 19%and an exergy efficiency of 40%and 28%for nitrogen and argon,respectively.Here,with the nitrogen as working fluid undergoes a complete Brayton Cycle,while the argon based power plant goes through a combined Brayton and Rankine Cycle.Besides,the economic analysis shows that the payback period of this proposed system is only 2.2 years,utilizing the excess heat from a 5 MW/40 MWh LAES system.The findings suggest that the waste energy based power plant could be co-located with the LNG terminal and LAES plant,providing additional power output and reducing energy waste.

Dose-dense paclitaxel plus carboplatin vs.epirubicin and cyclophosphamide with paclitaxel as adjuvant chemotherapy for high-risk triple-negative breast cancer

Objective:The objective of this open-label,randomized study was to compare dose-dense paclitaxel plus carboplatin(PCdd)with dose-dense epirubicin and cyclophosphamide followed by paclitaxel(ECdd-P)as an adjuvant chemotherapy for early triple-negative breast cancer(TNBC).Methods:We included Chinese patients with high recurrence risk TNBC who underwent primary breast cancer surgery.They were randomly assigned to receive PCdd[paclitaxel 150 mg/m2 on d 1 and carboplatin,the area under the curve,(AUC)=3 on d 2]or ECdd-P(epirubicin 80 mg/m2 divided in 2 d and cyclophosphamide 600 mg/m2 on d 1 for 4 cycles followed by paclitaxel 175 mg/m2 on d 1 for 4 cycles)every 2 weeks with granulocyte colony-stimulating factor(G-CSF)support.The primary endpoint was 3-year disease-free survival(DFS);the secondary endpoints were overall survival(OS)and safety.Results:The intent-to-treat population included 143 patients(70 in the PCdd arm and 73 in the ECdd-P arm).Compared with the ECdd-P arm,the PCdd arm had significantly higher 3-year DFS[93.9%vs.79.1%;hazard ratio(HR)=0.310;95%confidence interval(95%CI),0.137-0.704;log-rank,P=0.005]and OS(98.5%vs.92.9%;HR=0.142;95%CI,0.060-0.825;log-rank,P=0.028).Worse neutropenia(grade 3/4)was found in the ECdd-P than the PCdd arm(47.9%V5.21.4%,P=0.001).Conclusions:PCdd was superior to ECdd-P as an adjuvant chemotherapy for early TNBC with respect to improving the 3-year DFS and OS.PCdd also yielded lower hematological toxicity.Thus,PCdd might be a preferred regimen for early TNBC patients with a high recurrence risk.

Oxygen and nitrogen-doped metal-free carbon catalysts for hydrochlorination of acetylene

Activated carbon was tested as metal-free catalyst for hydrochlorination of acetylene in order to circumvent the problem of environment pollution caused by mercury and high cost by noble metals. Oxygen-doped and nitrogen-doped activated carbons were prepared and characterized by XPS, TPD and N2 physisorption methods. The influences of the surface functional groups on the catalytic performance were discussed base on these results. Among all the samples tested, a nitrogen-doped sample, AC-n-US00, exhibited the best performance, the acety- lene conversion being 92% and vinyl chloride selectivity above 99% at 240 ~C and C2H2 hourly space velocity 30 h- 1. Moreover, the AC-n-US00 catalyst exhibited a stable performance during a 200 h test with a conversion of acetylene higher than 76% at 210 ~C at a C2H2 hourly space velocity 50 h 1. In contrary, oxygen-doped catalyst had lower catalytic activities. A linear relationship between the amount of pyrrolic-N and quaternary-N species and the catalytic activity was observed, indicating that these nitrogen-doped species might be the active sites and the key in tuning the catalytic performance. It is also found that the introduction of nitrogen species into the sample could significantly increase the adsorption amount of acetylene. The deactivation of nitrogen- doped activated carbon might be caused by the decrease of the accessibility to or the total amount of active sites.

Energy storage for black start services:A review

With the increasing deployment of renewable energy-based power generation plants,the power system is becoming increasingly vulnerable due to the intermittent nature of renewable energy,and a blackout can be the worst scenario.The current auxiliary generators must be upgraded to energy sources with substantially high power and storage capacity,a short response time,good profitability,and minimal environmental concern.Difficulties in the power restoration of renewable energy generators should also be addressed.The different energy storage methods can store and release electrical/thermal/mechanical energy and provide flexibility and stability to the power system.Herein,a review of the use of energy storage methods for black start services is provided,for which little has been discussed in the literature.First,the challenges that impede a stable,environmentally friendly,and cost-effective energy storage-based black start are identified.The energy storagebased black start service may lack supply resilience.Second,the typical energy storage-based black start service,including explanations on its steps and configurations,is introduced.Black start services with different energy storage technologies,including electrochemical,thermal,and electromechanical resources,are compared.Results suggest that hybridization of energy storage technologies should be developed,which mitigates the disadvantages of individual energy storage methods,considering the deployment of energy storage-based black start services.

Efficacy and safety of duloxetine in Chinese breast cancer patients with paclitaxel-induced peripheral neuropathy

Objective： Chemotherapy with paclitaxel is associated with significant neurotoxicity that may offset patients＇ quality of life and therapeutic benefits. This prospective, non-randomized control study evaluated the efficacy and safety of an antidepressant drug, duloxetine, at 30 or 60 mg/d, in the treatment of paclitaxel-induced peripheral neuropathy（PIPN） in Chinese breast cancer patients.Methods：A total of 102 patients with a median age of 50（range,25–60）years,treated in the Department of Medical Oncology,National Cancer Center/Cancer Hospital,Chinese Academy of Medical Sciences and Peking Union Medical College,between November 2014 and January 2017 were finally enrolled.Stratified by baseline characteristics,the patients were classified into two groups,receiving either duloxetine or alternative antineurotoxicity drugs.During the course of the paclitaxel regimen,the eligibility criteria included sensory neuropathy,as evaluated by the National Cancer Institute-Common Toxicity Criteria for Adverse Events.The treatment consisted of receiving 30 mg duloxetine（for the first 4 weeks）and 60 mg duloxetine for an additional 8 weeks,or any other anti-neurotoxicity drug daily during the same crossover period.The improvement associated with PIPN from the patient’s perspective were assessed by the Functional Assessment of Cancer Therapy-Taxane（FACT-Tax）Scales,which contained questions scored from 0 to 4（0,not at all;4,very much;total score range,0–44）.Results：Duloxetine was more effective in decreasing PIPN（odds ratio=5.426;95%confidence interval,1.898–15.514;P=0.002）.Between duloxetine group and control group,the median（25th–75th percentiles）decreasing difference in the FACT-Tax pain score was 4（2–6）vs.1（0–4）（P=0.005）.Conclusions：Duloxetine is a promising and safe option with tolerable toxicity at a dose of 60 mg/d for Chinese breast cancer patients with PIPN.Non-neuropathy adverse events were mild and similar in both groups.The major toxicities of duloxetine included nausea,constipation,somnolence,dizziness and distention of the eyes.Further examination of the benefits of duloxetine in the prevention of PIPN is required.

Effects of runner design and pressurization on the microstructure of a high-pressure die cast Mg-3.0Nd-0.3Zn-0.6Zr alloy

To clarify the relationship between externally solidified crystals(ESCs)and other defects,e.g.,defect bands and pores,two dimensional(2D)and three dimensional(3D)characterization methods were adopted to analyze castings produced using a modified ingate system equipped with and without an ESC collector.The reduction of ESCs strongly reduced defect band width and shrinkage pore quantity.By reducing the quantity and size of ESCs,net-shrinkage pores were transformed into isolated island-shrinkage pores.We determined via statistical analysis that the mechanical properties of high pressure die castings were strongly related to the size and fraction of the ESCs rather than porosity volume.The reduction of ESCs also caused tensile transgranular fracture modes to transform into intergranular fracture modes.Additionally,casting pressurization strongly reduced pore morphology,volume,and size.

机械力诱导MHC-Ⅰ构象变化增强TCR抗原识别及T细胞活化

CD8+T细胞主要通过T细胞表面受体(T cell recep tor,TCR)识别并与Ⅰ型主要组织性复合物提呈的抗原(pMHC-Ⅰ)相互作用[1]。TCR对刺激型抗原的识别在CD8+T细胞毒性和适应性免疫中发挥着关键作用。许多证据表明机械力可以延长TCR与刺激性pMHC作用的键合时间(bond lifetime)形成抗原特异性逆锁键(catch bond)[2],并且这种逆锁键对抗原识别非常重要。然而,机械力调控TCR抗原识别的具体结构机制仍不清楚。通过分子动力学模拟、单分子生物膜力学探针、磁镊、T细胞活化实验和动物模型对此问题展开了系统的研究[4]。发现作用在TCR-pMHC-Ⅰ复合体上的拉力可以作用在TCR-pMHC-Ⅰ复合体上的拉力可以打破MHC-I分子内部α1-α2和β2结构域间的相互作用,导致α1-α2结构域旋转并发生构象变化。力诱导的MHC-I构象变化可以进一步别构地调节TCR与刺激性抗原肽及α1-α2结构域的构象及相互作用,诱导产生新的氢键,增强TCR-pMHC-Ⅰ之间的键合时间,但并不能增强TCR与抑制性pMHC-Ⅰ之间的作用。当用点突变阻断这些新形成的氢键,或者α1-α2和β2结构域被二硫键锁住时,最佳力诱导的TCR-pMHC-Ⅰ作用的键合时间明显缩短并且T细胞的活化受到抑制。另外,在人TCR和HLA-A2相互作用中发现了类似机制,并且与肿瘤相关的HLA-A2点突变[3]可以通过限制HLA-A2α1--α2和β2结构域之间的构象打开减弱TCR对肿瘤抗原的识别及T细胞的功能。研究结果表明,机械力诱导的MHC-I构象变化对TCR抗原识别和T细胞活化非常重要,进一步地阐明了机械力调控TCR抗原识别机制,为临床肿瘤的免疫治疗和药物设计提供了新思路和新靶点。

“Genetic scissors”CRISPR/Cas9 genome editing cutting-edge biocarrier technology for bone and cartilage repair

CRISPR/Cas9 is a revolutionary genome editing technology with the tremendous advantages such as precisely targeting/shearing ability,low cost and convenient operation,becoming an efficient and indispensable tool in biological research.As a disruptive technique,CRISPR/Cas9 genome editing has a great potential to realize a future breakthrough in the clinical bone and cartilage repairing as well.This review highlights the research status of CRISPR/Cas9 system in bone and cartilage repair,illustrates its mechanism for promoting osteogenesis and chondrogenesis,and explores the development tendency of CRISPR/Cas9 in bone and cartilage repair to overcome the current limitations.

The poisoning and regeneration effect of alkali metals deposed over commercial V_2O_5-WO_3/TiO_2 catalysts on SCR of NO by NH_3

In this study,commercial V2O5-WO3/TiO2catalysts were deactivated by loading with alkali metals(K and Na).These catalysts were then regenerated by washing with either deionized water or 0.5 mol/L H2SO4(through the ultrasonic-assisted method).The samples used in this research were characterized by NH3-temperature programmed desorption(TPD),and X-ray photoelectron spectroscopy(XPS).Results showed that Na2O and K2O doping can poison the V2O5-WO3/TiO2catalyst and that the poisoning effect of Na2O was stronger than that of K2O.However,the Na2O-loaded sample was easier to regenerate than the K2O-loaded sample.The surfaces of catalysts can be sulfated by washing with dilute sulfuric acid because strong acid sites adhere to the catalyst surface.SO42-could also promote catalyst activity.As indicated by the NH3-TPD findings,the deposition of Na2O and K2O could also reduce the amount of desorbed ammonia and destabilize the acid sites,especially strong chemisorption sites.XPS results revealed that catalysts were deactivated by the decrease in the concentration of chemisorbed oxygen[the Oa/(Oα+Oβ)ratio].In the Na2O-doped catalyst,much chemisorbed oxygen was lost(from 28.8%to10.6%).However,the decrease in the Oa/(Oα+Oβ)ratio was less significant in the K2O-doped catalyst(from28.8%to 23.5%).Nonetheless,the binding energies of O1s broadened with respect to both high and low energy.In particular,the binding energy of chemisorbed oxygen increased from 531.5 to 531.8 eV.

Inhalation treatment of primary lung cancer using liposomal curcumin dry powder inhalers

Lung cancer is the leading cause of cancer-related deaths. Traditional chemotherapy causes serious toxicity due to the wide bodily distribution of these drugs. Curcumin is a potential anticancer agent but its low water solubility, poor bioavailability and rapid metabolism significantly limits clinical applications. Here we developed a liposomal curcumin dry powder inhaler(LCD) for inhalation treatment of primary lung cancer. LCDs were obtained from curcumin liposomes after freeze-drying. The LCDs had a mass mean aerodynamic diameter of 5.81 μm and a fine particle fraction of 46.71%, suitable for pulmonary delivery. The uptake of curcumin liposomes by human lung cancer A549 cells was markedly greater and faster than that of free curcumin. The high cytotoxicity on A549 cells and the low cytotoxicity of curcumin liposomes on normal human bronchial BEAS-2B epithelial cells yielded a high selection index partly due to increased cell apoptosis. Curcumin powders, LCDs and gemcitabine were directly sprayed into the lungs of rats with lung cancer through the trachea. LCDs showed higher anticancer effects than the other two medications with regard to pathology and the expression of many cancer-related markers including VEGF, malondialdehyde, TNF-α, caspase-3 and BCL-2. LCDs are a promising medication for inhalation treatment of lung cancer with high therapeutic efficiency.

Mechanism of stall and surge in a centrifugal compressor with a variable vaned diffuser

To expand the stable operating range of compressors, understanding the mechanism of flow instability at low flow rates is necessary. In this paper, the mechanism of stall and surge in a centrifugal compressor with a variable vaned diffuser is experimentally investigated, where the diffuser blade setting angle can be adjusted. Many dynamic pressure transducers are mounted on the casing surface of the compressor. From the design condition to surge, dynamic pressure data is recorded throughout the gradual process. According to the signal developing status, the typical modes of compressor instability are defined in detail, such as stall, mild surge, and deep surge. A relatively high-frequency stall wave originates in the impeller and propagates to the diffuser, and finally stimulates a deep surge in the compressor. The compressor behavior during surge differs at different diffuser vane angles. When the diffuser vane angle is adjusted, both the unstable form and the core factor affecting the overall machine stability change. A specific indicator is proposed to measure the instability of each component in a compressor, which can be used to determine the best region for stability extension technologies, such as a holed casing treatment, in different compressor applications.

Fabrication of electrochemically-modified BiVO_(4)-MoS_(2)-Co_(3)O_(4)composite film for bisphenol A degradation

A new electrochemically-modified BiVO_(4)-MoS_(2)-Co_(3)O_(4)(represented as E-BiVO_(4)-MoS_(2)-Co_(3)O_(4))thin film electrode was successfully synthesized for environmental application.MoS_(2)and Co_(3)O_(4)were grown on the surface of Bi VO 4 to obtain BiVO_(4)-MoS_(2)-Co_(3)O_(4).E-BiVO_(4)-MoS_(2)-Co_(3)O_(4)film was achieved by further electrochemical treatment of BiVO_(4)-MoS_(2)-Co_(3)O_(4).The asprepared E-BiVO_(4)-MoS_(2)-Co_(3)O_(4)exhibited significantly enhanced photoelectrocatalytic activity.The photocurrent density of E-BiVO_(4)-MoS_(2)-Co_(3)O_(4)thin film is 6.6 times that of Bi VO 4 under visible light irradiation.The degradation efficiency of E-BiVO_(4)-MoS_(2)-Co_(3)O_(4)for bisphenol A pollutant was 81.56%in photoelectrochemical process.The pseudo-first order reaction rate constant of E-BiVO_(4)-MoS_(2)-Co_(3)O_(4)film is 3.22 times higher than that of Bi VO 4.And its reaction rate constant in photoelectrocatalytic process is 14.5 times or 2 times that in photocatalytic or electrocatalytic process,respectively.The improved performance of E-BiVO_(4)-MoS_(2)-Co_(3)O_(4)was attributed to the synergetic effects of the reduction of interfacial charge transfer resistance,the formation of oxygen vacancies and sub-stoichiometric metal oxides and higher separation efficiency of photogenerated electron-hole pairs.E-BiVO_(4)-MoS_(2)-Co_(3)O_(4)is a promising composite material for pollutants removal.