Dynamic behavior of droplet formation in dripping mode of capillary flow focusing

Experimental study on the liquid dripping in a capillary flow focusing process is performed. Due to the high-speed gas stream that drives the inner liquid co-flowing through an orifice, complex phenomena for the droplet formation in dripping regime can be found as the gas pressure drop and the liquid flow rate change. Periodic dripping mode can produce uniform droplets, and non-periodic ones can result in satellites and droplets of different diameters. The droplet-droplet coalescence in the core of co-flowing gas stream is also obtained. The size of resultant droplets is measured under different values of gas pressure drop and liquid flow rate. It can be seen that the droplet size tends to decrease as the gas pressure drop increases and keeps nearly the same as the liquid flow rate increases. The results also indicate that the dynamic behavior of droplet formation in dripping mode of capillary flow focusing is mainly dominated by the gas pressure drop, and the capillary flow focusing technique can produce droplets with high throughput even in the dripping regime.Cited as: Si, T. Dynamic behavior of droplet formation in dripping mode of capillary flow focusing. Capillarity, 2021, 4(3): 45-49, doi: 10.46690/capi.2021.03.0

Experimental study on a solar-powered thermochemical sorption refrigeration system using strontium chloride/EG-ammonia working pair

An experimental intermittent thermochemical refrigeration system using strontium chloride (SrCl2)–ammonia reaction is described, which mainly consists of an adsorption bed and an evaporator/condenser. The strontium chloride is used as solid absorbent and ammonia as refrigerant. A kind of consolidated composite material based on expanded graphite and strontium chloride is developed firstly, then the composite material is filled into the adsorption bed. The process of desorption or regeneration of strontium chloride is driven by solar energy, and the temperature range of the heating fluid is from 90 to 110℃, which can be heated by solar energy collected by low cost solar flat plate collectors. In the evaporation–absorption process, the evaporating temperature is between -10 and -35℃. The theoretical analysis shows that this refrigeration system is technical feasibility

Slip-enhanced Rayleigh-Plateau instability of a liquid film on a fibre

Boundary conditions at a liquid-solid interface are crucial to dynamics of a liquid film coated on a fibre. Here a theoretical framework based on axisymmetric Stokes equations is developed to explore the influence of liquid-solid slip on the Rayleigh-Plateau instability of a cylindrical film on a fibre. The new model not only shows that the slip-enhanced growth rate of perturbations is overestimated by the classical lubrication model, but also indicates a slip-dependent dominant wavelength, instead of a constant value obtained by the lubrication method, which leads to larger drops formed on a more slippery fibre. The theoretical findings are validated by direct numerical simulations of Navier-Stokes equations via a volume-of-fluid method. Additionally, the slip-dependent dominant wavelengths predicted by our model agree with the experimental results provided by Haefner. et al.[Nat. Commun., Vol. 6(1), 2015, 18 pp. 1-6]

Role of Danmu Function in User Experience and Engagement: A Double-edged Sword

Digital video sites currently seek new ways to build a platform to encourage user engagement and enable users to connect with one another through multiple means and channels. The widespread introduction of danmu technology has aroused concerns of academia. However, comparatively little work has been done to explicate the role of danmu function and research progress has been falling behind practical interest. In this study, we seek to investigate user experience and engagement to understand the double-side effect of danmu technology. Using S-O-R framework, we propose that danmu features, namely proximity and coherence, play essential roles in creating augmentation experience of para-social interaction and degradation experience of goal impediment and information overload. Additionally, we investigate user experience to understand user engagement in the danmu-enabled situation. We suggest that para-social interaction will elicit increased user engagement; yet goal impediment and information overload will lead to less user engagement

A Green Peel on STEAM Education: An Innovative and Sustainable Education Scheme Integrating STEAM and Environmental Education

The STEAM education in China started late so it is still in its infancy. Its curriculum is partial to IT and Internet, which is against the original purpose of interdisciplinary education in STEAM. Meanwhile, the resources put on environmental education are minute so the environmental awareness of citizens is very weak. Therefore, we have proposed an innovative education scheme—integrating STEAM, environmental and family education together so that they can complement each other. Such a scheme not only makes STEAM education more comprehensive, it can also make environmental education more effective. To implement our scheme, we have made use of peel wastes to produce a new natural peel crayon. The whole production process is further developed to a curriculum which serves as an education model that combines all five elements in STEAM education. Together we have created a ‘learning package’ that takes care of students’ individuality in education. After putting it into practice, we have received positive feedbacks from both parents and children. Furthermore, we have done several standard tests to ensure the safety of our peel crayons. Results have proved the feasibility of our new education scheme. Such a scheme has provided a role model for integration of environmental and STEAM education. In the future, we hope to develop more education models to make our learning package more diverse and applied in different aspects

Determination of Pb (Lead), Cd (Cadmium), Cr (Chromium), Cu (Copper), and Ni (Nickel) in Chinese tea with high-resolution continuum source graphite furnace atomic absorption spectrometry

AbstractThe contents of lead, cadmium, chromium, copper, and nickel were determined in 25 tea samples from China, including green, yellow, white, oolong, black, Pu'er, and jasmine tea products, using high-resolution continuum source graphite furnace atomic absorption spectrometry. The methods used for sample preparation, digestion, and quantificational analysis were established, generating satisfactory analytical precisions (represented by relative standard deviations ranging from 0.6% to 2.5%) and recoveries (98.91–101.32%). The lead contents in tea leaves were 0.48–10.57 mg/kg, and 80% of these values were below the maximum values stated by the guidelines in China. The contents of cadmium and chromium ranged from 0.01 mg/kg to 0.39 mg/kg and from 0.27 mg/kg to 2.45 mg/kg, respectively, remaining in compliance with the limits stipulated by China's Ministry of Agriculture. The copper contents were 7.73–63.71 mg/kg; only 64% of these values complied with the standards stipulated by the Ministry of Agriculture. The nickel contents ranged from 2.70 mg/kg to 13.41 mg/kg. Consequently, more attention must be paid to the risks of heavy metal contamination in tea. The quantitative method established in this work lays a foundation for preventing heavy metal toxicity in human from drinking tea and will help establish regulations to control the contents of heavy metals in tea

Studies on the properties and the thermal decomposition kinetics of natural rubber prepared with calcium chloride

To evaluate calcium chloride coagulation technology, two kinds of raw natural rubber samples were produced by calcium chloride and acetic acid respectively. Plasticity retention index (PRI), thermal degradation process, thermal degradation kinetics and differential thermal analysis of two samples studied. Furthermore, thermal degradation activation energy, pre-exponential factor and rate constant were calculated. The results show that natural rubber produced by calcium chloride possesses good mechanical property and poor thermo-stability in comparison to natural rubber produced by acetic acid.<br /

A New Innovative IoT Watch Reduces Excessive Consumption And Its Implications To Green Logistics

Excessive consumption leads to 7 trends of crises, including destruction of the atmosphere, energy crisis, social decline and conflicts. Over consumption also deteriorates human health. To reduce excessive consumption not only can improve health, it can also reduce transportation from consumption, livestock raise and sale, and medical care. The reducing over consumption can benefit human health and environmental protection through supply chain management. This motivates us to devise an innovative product. Our imaginative innovative product is a new smart watch (SW) which improves several new features based on Apple Watch. After a survey to potential users, it reveals that the new features can help reduce the excessive consumption, deterioration of the human health, transportation, healthcare as well as the destruction of the environment. Enterprises can also achieve their social responsibilities through the implementation and popularization of the SW as soon as possible