多巴胺对碳纤维增强聚苯硫醚复合材料界面性能的影响

碳纤维增强聚苯硫醚复合材料(CF/PPS)因其具有优异的综合性能被广泛关注,但实际应用中发现碳纤维与聚苯硫醚的界面结合并不理想,因此,改善CF/PPS界面结合强度来提升其宏观力学性能就有着深远的理论意义和应用价值。文中基于微球脱粘技术,将具有优良黏附性的多巴胺水溶液作为界面改性剂,对纤维进行表面改性,采用微球脱粘实验和宏观拉伸等实验测试探究了不同多巴胺浓度对CF/PPS界面性能的影响。结果表明,当多巴胺浓度为2 g/L时,聚多巴胺在碳纤维表面均匀黏附,形成较好的微纳结构,涂覆效果最佳,表观界面剪切强度最大为36.09 MPa,较未改性前增加13.50%;PDA-CF2/PPS拉伸试样的断面呈现凹凸不平的形态,拔出的碳纤维上残留树脂基体最多,具有良好的界面改性效果。

连续碳纤维增强聚苯硫醚复合材料的3D打印及力学性能优化

采用连续碳纤维增强聚苯硫醚(CCF/PPS)预浸丝材为原料,通过3D打印制备出不同工艺参数条件下的弯曲试样和层间试样。采用扫描电镜、显微CT、差示扫描量热仪、弯曲性能和层间性能等测试方法对3D打印CCF/PPS复合材料的结构和性能进行了研究。结果表明,打印制品相邻打印层之间的界面、相邻打印线条之间的界面、孔隙结构和结晶结构都对打印制品的弯曲性能和层间性能有重要影响。当打印层厚为0.2 mm、沉积空间为0.40 mm~2,并采用后热处理时,打印制品可获得最高为699 MPa的弯曲强度和43.32 MPa的层间剪切强度,在连续纤维增强热塑性复合材料3D打印研究领域处于领先水平。

α/β复合成核剂协同增强煤基均聚聚丙烯力学性能

针对煤基均聚聚丙烯(PP)结晶过程中β晶型成核生长能力较弱、冲击强度较低的问题,利用差示扫描量热仪(DSC)、广角X射线衍射仪(WAXD)和万能材料实验机研究了单独添加a,β和复合添加a/β成核剂对煤基均聚聚丙烯的结晶性能和力学性能的影响。研究表明,单独添加a或β成核剂均会存在一定的性能缺陷。DSC结果表明,a/β复合成核剂中β成核剂的存在会抑制a晶型的生成,β晶熔融峰强度会增加,在降温结晶曲线中也呈现出明显的β晶优先成核现象。WAXD结果表明,复合成核剂可以提高聚丙烯的β晶体的相对含量(K_(β))。a/β复合成核剂的加入有助于同时实现煤基均聚聚丙烯的刚韧平衡,当复合成核剂质量分数为0.15%、a/β比例为1:2时,PP的拉伸强度、断裂伸长率和冲击强度分别提高了15.9%,305.3%和72.5%。

Electrospun antibacterial nanofibers for wound dressings and tissue medicinal fields:A Review

Bacterial infections are a major cause of chronic infections.Thus,antibacterial material is an urgent need in clinics.Antibacterial nanofibers,with expansive surface area,enable efficient incorporation of antibacterial agents.Meanwhile,structure similar to the extracellular matrix can accelerate cell growth.Electrospinning,the most widely used technique to fabricate nanofiber,is often used in many biomedical applications including drug delivery,regenerative medicine,wound healing and so on.Thus,this review provides an overview of all recently published studies on the development of electrospun antibacterial nanofibers in wound dressings and tissue me-dicinal fields.This reviewer begins with a brief introduction of electrospinning process and then discusses electrospun fibers by incorporating various types of antimicrobial agents used as in wound dressings and tissue.Finally,we finish with conclusions and further perspectives on electrospun antibacterial nanofibers as 2D biomedicine materials.

Sound production in marbled rockfish (Sebastiscus marmoratus) and implications for fisheries

Recently,several rockfish species(genus Sebastes)have been reported to be soniferous.To determine whether an additional rockfish species produces sounds,passive acoustic recordings were analyzed from captive marbled rockfish(Sebastiscus marmoratus)during the non-spawning season.Three distinct sounds were identified based on frequency features.The common characteristics among all sounds were low frequency(below 300 Hz)and rapidly dampened pulses consisting of 3–5 acoustic energy cycles.During free-swimming conditions in the canvas tank,the fish produced voluntary sounds with lower frequencies than the disturbance sounds produced by individuals during prodding.Two types of sounds were identified in the disturbance context:one type consists of single or double pulses with two peak frequencies,and another type consists of a series of pulses with a single peak frequency.These results suggest that specific-species and behavior-associated sounds are potentially useful in passive acoustical surveys to monitor rockfish populations and distributions remotely.

An efficient non-iterative algorithm to estimate the apparent diffusion coefficient of water molecules in the magnetic resonance diffusion imaging experiments

Many studies have shown that the magnetic resonance signal decay with an extend range of diffusion weighting(b-factor)is a bi-exponential attenuation in the diffusion-weighted magnetic resonance imaging experiments in vivo.Based on this feature and the two-compartmental model,we propose a twice-linear-fitting(TLF)algorithm to estimate the apparent diffusion coefficient(ADC)of the water molecules instead of the commonly used iterative Levenberg–Marquardt(LM)method.The TLF algorithm consists of two liner fitting steps to estimate the fast and the slow apparent diffusion coefficients and their sizes,respectively.It is unnecessary to guess the initial values in the whole fitting process.The time consumption of the TLF algorithm is much less than that of the iterative LM method.Moreover,the TLF algorithm may avoid the extraneous solutions,which often deteriorates the results of the LM method.Compared with the iterative fitting method,the TLF algorithm is a reliable and timeefficient approach to estimate the ADC of water molecules in vivo in magnetic resonance diffusion-weighted imaging experiments.

Effectiveness of stocking Sparus macrocephalus fry in situ in the East China Sea

The sea area surrounding Baishishan Island has abundant fishery resources because of its plentiful food and rocky reefs that provide refuge from predators.However,overfishing has occurred in many areas and some species’local populations need to be replenished through stocking programs.This case study,using Sparus microcephalus as the test species,designed and analyzed detailed stocking strategies to improve the survival ratio and control the active range of the released fishes.Controlled variables included release location,release time,and tidal level.Two stocking strategies were designed,executed,and evaluated for comparison.A traditional stocking method was applied to the high flow area of Baishishan Island in Xiangshan Bay,East China Sea.The released fry were transported by boat and released to the sea using buckets.Released fish were traced using plastic tags.The average distance of the 19 recaptured fry from the release point was 7.6 km with 52.9%mortality rate.The distance at recapture and mortality rate among recaptured individuals showed that the traditional releasing method was not successful.An in situ stocking method was used in a low tide area and natural process was imitated to decrease the stress response and promote physiological adaptation.The purpose of this method was to prolong the release process applying temporary net cages at the release location,which resulted in a regional distribution of the released fish and possibly improving the food availability.A new Sr+tagging technique was adopted to evaluate the release effect and quantify comparative release data.Only 1 fish among the 354 caught was found farther than 1 km from the release point in the following 6 months.The results validated the promotion of the new stocking technique.

根际真菌新功效:提供哌啶酸而增强植物的抗病虫能力

植物与根际、叶际及内生微生物之间的物质和信息交流是植物-微生物互作研究的核心内容之一.不同根际或内生真菌的定殖是多数植物生长发育及抗逆的重要保障.绿僵菌(Metarhizium spp.)是一类种昆虫病原真菌[1],可穿透害虫体壁而直接感染和杀死害虫.

Influence of sampling frequency on detectability of fish community and fish species in a fishery-independent survey

Understanding the dynamics and regulation of a particular ecological process requires monitoring of the process at appropriate spatial and temporal scales.Information collected at an inappropriate spatiotemporal scale may be insufficient for capturing spatio-temporal dynamics of fish populations and community.In this study,a Monte Carlo method was developed to evaluate the detectability performances of different sampling frequencies,sampling timings and sampling intensities on fish community indices and fish species.Species richness indices tended to decrease with an increased sampling frequency,while species diversity indices had small changes in response to changes in sampling frequency.The diversity index was more likely to be influenced by the choice of sampling timing compared to the richness index.The total number of species,especially seasonal and rare species present in the simulated sampling,increased with sampling frequency.Although sampling frequency is more important than sampling intensity,sampling intensity is also important for the detectability of fish species.This study showed that sampling frequency and intensity could greatly influence the estimation of fish community.Choices of sampling timing,sampling frequency and intensity may result in different estimates of fish species compositions and community structure.It is very necessary to consider the importance of sufficient sampling frequency and intensity in a survey program.