Influence of Polymer Binder on the Physical Properties and Stability of Engineering Spoil on a Slope

An experiment was performed to study the influence of polymer binders on the physical properties,and stability against a simulated rainfall,of a slope consisting of engineering spoil.Results showed that low polymer binder concentrations(≤500g/m3) could enhance the air permeability and moisture-retaining capacity of the engineering spoil;however,adding more polymer binder made the hardness of the engineering spoil increase and then decline.With the increase of polymer binder concentrations,the surface(0-5cm) permeability of the engineering spoil decreased but the permeability of the lower layers(5-10cm) increased.Polymer binders might reduce runoff and sediment,but the effect becomes weaker with the increase of rainfall.The results of this study have significance for engineering practices.Further experiments are needed to study the effects of binders under other conditions,such as natural rainfall,different slopes,different rock types,different degrees and spoil weathering and different added material,and the chemical interaction between soil and polymer binders.

Single-mode lasing via loss engineering in fiber-taper-coupled polymer bottle microresonators

Due to the lack of mode selection capability, single whispering-gallery-mode(WGM) lasing is a challenge to achieve. In bottle microresonators, the highly nondegenerated WGMs are spatially well-separated along the long-axis direction and provide mode selection according to their axial mode numbers. In this work, we use a loss-engineering approach to suppress the higher-order WGMs and demonstrate single-mode lasing emission in small polymer bottle microresonators. The fiber tapers are not only used to couple pump light into the bottle microresonators to excite the WGMs but also to bring optical losses that are induced from the diameter mismatch between fiber tapers and microresonators. By adjusting the coupling positions, the diameters of fiber tapers, and the coupling angles, single fundamental-mode lasing is efficiently generated with side-mode suppression factors over 15 dB. Our loss-engineering approach is convenient just by moving the fiber taper and may findpromising applications in miniature tunable single-mode lasers and sensors.

Electrospun Polyhydroxybutyrate/Hydroxyapatite Nanohybrids:Microstructure and Bone Cell Response

A substantial amount of nanosized hydroxyapatite（HAp） was tried to incorporate into the electrospun polyhydroxybutyrate（PHB）, and electrospinning parameters were optimized to fabricate defect-free PHB/HAp fibers with the smallest possible diameter. According to the results, while the needle inner diameter could not be an effective factor for controlling the fiber morphology, the fiber diameter was observed to increase with increasing the applied voltage and solution concentration. More importantly, it was found that nanoparticles could be successfully encapsulated and distributed inside the ultrafine fibers fabricated under relatively optimum conditions. In vitro cell assays demonstrated that while preosteoblasts had high cell viability and cell spreading on the fibrous nanohybrids, cell metabolic activity can also increase with increasing incubation time. Accordingly, encapsulation of HAp nanoparticles within the PHB in the fibrous form may be promising for bone regeneration applications.