Reliable Determination of Contact Angle from the Liquid Fence.

Traditional methods of measuring contact angles often face difficulties in precisely defining the three-phase contact points. A novel method for accurately defining three-phase contact points based on liquid fences is proposed in this article. The tested liquid is placed in a cubic liquid fence composed of a pair of narrow strips of the tested solid and a pair of transparent wide strips. The transparent wide strip serves as the measurement window, and the surface tension of the liquid on it can be almost ignored. In experimental measurements, the horizontal coordinates of the end points of the liquid profile are fixed by the liquid fence, thus determining the horizontal coordinates of the three-phase contact points, which helps to accurately survey the contact angle. Additionally, since the parameters of the liquid fence are known, the size of the contact angle can also be calculated by measuring the height of the liquid level dome inside the liquid fence. Using the electric wetting effect as an example, we experimentally extracted a series of liquid contour maps with circular tops and square columns under varying voltages. The relationship curve between contact angle and voltage variation was obtained using the above methods, and a contact angle variation tendency seemed to agree well with the theoretical value.

Tunable fiber attenuator for electrically wet-driven micromirrors.

Herein we report an electronically controlled tunable fiber-optic attenuator that leverages the microfluidic electro-wetting effect, which enables a fine-tuning of the solid-liquid interface wetting angle to control the micro-reflector, thus regulating the lens fiber coupling efficiency. Theoretical calculations indicated an optical attenuation regulation effect of 0-45.0 dB in the voltage range of 0-30.0 V. Experimental results align closely with theoretical calculations, demonstrating an attenuation range of 0.59-43.0 dB within a voltage variation range of 0-25.0 V, with control accuracy of 0.56 dB. Our study unveils the potential for designing fiber-optic attenuators with varying tuning accuracy by precisely adjusting the solid-liquid interface wetting angle.

[Impact of reclaimed water irrigation on soil chemical properties and culturable microorganisms ].

This research used batch soil column experiment to study the effects of irrigating with reclaimed water and tap water on the soil chemical properties and culturable microorganisms. The results indicated that reclaimed water could markedly increase the soil organic material (OM) and total nitrogen (TN) content, but it had no obvious effect on total phosphorus (TP), available phosphorus (AP) and pH value. Reclaimed water irrigation could significantly enhance the amounts of surface soil bacteria and actinomycetes at a depth of 0-20 cm, but it had little effect on the biomass of 20-40 cm and 40-60 cm soil layers. The dominant bacteria in tap water irrigation area was the genus Bacillus whereas that of reclaimed water irrigation area was the genus Acinetobacter. Tap water irrigation area had four endemic genera and reclaimed water irrigation area had six endemic genera. Reclaimed water had no obvious effect on the microbial community Shannon diversity of 0-20 cm soil layer, while it decreased Pielou evenness index, and improved Margalef richness index. Through SPSS 17. 0 correlation analysis between soil microbes quantity and soil chemical properties, it was shown that the soil microbes quantity was positively correlated with OM, TN, TP and AP, but negatively correlated with soil water content (SWC) and pH value. Based on CANOCO 4.5 detrended correspondence analysis (DCA) and redundancy analysis (RDA) between soil microbes species and soil chemical properties, it was shown that AP had the strongest correlation with the microbial community (P = 0.002). TN and TP had larger impact on Streptococcus, Aeromonas and Neisseria. OM and AP had larger impact on Aerococcus, Planococcus and Halobacterium.

Social interaction and participation: formative evaluation of online CME modules.

INTRODUCTION: This exploratory study examines Canadian physicians' participation in online social activities and learning discussions, perceptions of online social closeness, barriers and motivators to participation, and perceptions of the impact of course duration and face-to-face meetings on learning. METHODS: Formative evaluations were administrated to physicians participating in two online continuing medical education (CME) courses. Responses were recorded and calculated by the Blackboard Learning System. Content analysis was used to categorize comments and identify influencing factors. Online postings were counted to measure participation in the learning activities. RESULTS: The participation rate of 158 physicians and 10 facilitators in online social activities was very low. Forty-five percent of responding participants reported that more time for discussion would help them learn more; 62% stated that the initial face-to-face meeting helped improve online social relations and increase peer interactions online. Thirty-five percent of respondents reported participating in online social activities, while 29% had no time to do so, and 18% were not interested in doing so. Thirty-five percent felt closer or more connected to their peers after two discussion sessions; 11% did not feel closer because of their low participation; and 16% did not feel closer because of inadequate peer interaction. On the two evaluations, 49% and 22% of respondents, respectively, perceived lack of time and social bonding as major barriers to participating in learning discussion. DISCUSSION: Lack of time and peer response were given as the main reasons for low participation in social activity and learning discussions. Time and social bonding were major barriers to learning discussion. Course usefulness and participants' desire, commitment, and time management skills helped overcome barriers. Facilitators needed training in online systems and facilitation skills. Longer course duration and realistic pacing would probably foster more social interaction and greater course participation.

Finite element modeling of acoustic field induced by laser line source near surface defect.

A numerical model of acoustic field induced by laser line source near the surface defect is established by finite element method (FEM), where a surface notch of rectangular shape has been introduced to represent the fatigue defect for the convenience of modeling. After calculating numerically the transient displacement distributions, which are generated by the laser irradiation, the ultrasonic wave modes on the surface and in the body of the plate material are presented in details. The longitudinal, transverse and surface acoustic waves (SAWs) excited by laser pulses near surface notch are compared under the situations that the notch depths are different. As the notch depth increases, the directivity of the bulk waves generation changes greatly. The amplitude of the reflected SAW rises observably at the same time, which is observed experimentally when the laser source is shifted near the surface notch in scanning laser line source (SLLS) measurement. Another effect induced by the surface notch is the time lag of the transmitted SAW pulse with respect to the original incident pulse. These phenomena can be explained from the results. The conclusions can be used to surface notch depth evaluation.