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Surface wetting properties control is crucial to various applications, such as anti-wetting, self cleaning and heat transfer processes. Design of surface wetting properties can be achieved by mechanical and chemical methods. The mechanical methods include surface roughness design, while chemical methods involve changing the intrinsic wetting properties of the surface. The intrinsic wetting properties, which can be characterized by the contact angle on a flat surface, can reach a maximum of 120°. The combination of roughness and chemical treatment can distinctly enlarge the contact angle range, including wicking (zero contact angle), partial wetting (finite contact angle) and superhydrophobicity (contact angle larger than 150°). Thus, a lot of works showing various types of structure design with different wettability properties can be found in the literature. Among the various possible micro-structures, conical structures (well-known structures found in the Lotus leaf) are frequently used due to their unique properties. The Lotus leaf has a lot of micro-scale tapered bumps and also nano-scale roughness. Various previous works artificially produce this kind of conical structures and achieve similar wetting properties. However, a lot of these works use non-regular conical like structures, while the number of works using patterned conical structured surfaces is limited. Therefore, it remains unclear how the different conical geometries can affect the wetting properties of the surface. To bridge this gap, we fabricate patterned conical micro-structured surfaces with different cones geometry and topography and study how the static and dynamic wetting properties are affected by the structures. The conical micro-structures are produced on silicon substrates using photo-lithography and plasma etching techniques. By varying the fabrication process recipe, different types of conical structures are fabricated. This thesis presents the study of both static and dynamic wetting properties for various conical structured surfaces. In addition, cylindrical pillar structured surfaces are also used for comparison. It is found that the conical structured surface can be designed to be super-repellent for intrinsic contact angles larger than 90°. The conical half-apex angle of the cones is important for suppressing the Cassie-Wenzel transition. This work not only provides more insights into the effect of conical structures on wetting but also shows that conical structures can be a good path for achieving superhydrophobicity. In addition to the previous study of Cassie wetting state on conical structures, we subsequently investigate how the partial wetting Wenzel droplet shape is affected by the conical pillars sidewall geometry. We compare truncated cone pillars with cylindrical pillar surfaces. Previous works show that pillar height/pitch can affect the liquid droplet final shape. However, we observe that the drop shape on truncated cones and on cylindrical pillars is different even when they have the same pitch and height. Besides, the drop shape on these two types of surfaces is also evolving in a different way as the impact Weber number increases. This work reveals that the micro-structures side wall topography can influence the final drop shape. We further investigate conical structures as a means to increase the anti-wetting properties of surfaces during impact of low surface tension droplets. We fabricate conical pillars surfaces with re-entrant like side wall roughness all along the side wall, which looks like a tree-branch topography. Low surface tension drop impact experiments are conducted on these surfaces and we show that the tree-branch like structure does improve the anti-wetting performance by exhibiting a higher critical Weber number (the Weber number starting to show partial rebound), compared with conical structures without a sidewall roughness. The tree-branch like structures can reduce the solid-liquid contact and have higher resistance to penetration, and thus can reach higher anti-wetting performance than other reported rigid surfaces. Finally, we explore how conical and cylindrical pillar structures behave for water droplets impacting at different Weber numbers. We show how the liquid residue size is affected when the droplet impacts above the critical Weber number for conical and cylindrical pillars. It is shown that the conical pillar surfaces have higher contact angle and lower hysteresis while the cylindrical pillars show lower contact angle and higher hysteresis for dense array surfaces. At low Weber number, conical structures surfaces show less energy dissipation compared with cylindrical structures surfaces. For the same height and pitch, the cylindrical pillars show a higher critical Weber number compared with conical pillars due to the large solid-liquid contact at the pillar top. However, the liquid residue when the Weber number is above the critical Weber number for the cylindrical case is larger than for the conical pillar case. We propose that the liquid residue size is affected by the We number, anti-penetration ability and liquid mobility inside the structures. Liquid mobility within the conical structures is lower than for the cylindrical ones, which leads to less wetted area due to less open space inside the structures. This work not only reveals how the conical geometry can affect the wetting properties but also shows that conical structured surfaces are a good candidate for anti-wetting performance enhancement, which can be useful for various applications.

Progress in icephobicity has been made in recent years. However, the majority of the icephobic surfaces reported are relying on mechanisms of static nature, and maintaining low ice adhesion of these surfaces at extreme temperature as low as -60 ℃ has been challenging. Dynamic anti-icing surfaces, that can melt ice or change the ice-substrate interfaces from solid to liquid phase after the formation of ice serves as a viable alternative. In this study, liquid layer generators (LLGs), which can release ethanol to the ice-solid interface and convert ice-substrate contact from solid-solid to solid-liquid-solid mode were introduced. Excellent icephobicity on surfaces with an ethanol lubricating layer is found to withstand extremely low temperature (-60 ℃) by both molecular dynamic simulations and experiments. Two prototypes of LLG, one by packing ethanol inside and the other by storing replenishable ethanol below the substrate, are fabricated. The LLGs are able to constantly release ethanol for maximally 593 days without source replenishing. Both prototypes demonstrate super-low ice adhesion strength of 1.0~4.6 kPa and 2.2~2.8 kPa at -18 ℃. For selected samples, by introducing interfacial ethanol layer, ice adhesion strength on the same surfaces unprecedented decreased from 709.2~760.9 kPa to 22.1~25.2 kPa at low temperature of -60 ℃.

When employing observations from multiple Global Navigation Satellite System (GNSS) the performance of real-time (RT) GNSS meteorology can be improved. In this paper, we describe an operational RT system for extracting zenith tropospheric delay (ZTD) using a modified version of the PPP-wizard. Multi-GNSS, including GPS, GLONASS and Galileo, observation streams are processed using a RT PPP strategy based on RT satellite orbit/clock products from CNES. A continuous experiment for 30 days is conducted, in which the RT observation streams of 20 globally distributed stations are processed. The initialization time and accuracy of the RT troposphere products using single/multi-system observations are evaluated. The effect of RT PPP ambiguity resolution is also evaluated. The results reveal that the RT troposphere products based on single system observations can fulfill the requirements of meteorological application, in which the GPS-only solution is better than the GLONASS-only solution in both initialization and accuracy. The performance can also be improved by applying RT PPP ambiguity resolution and utilizing multi-GNSS observations. Specifically, we notice that the ambiguity resolution is more effective in improving the accuracy, whereas the initialization process can be better accelerated by multi-GNSS observations. Combining all systems, RT troposphere products with an average accuracy of about 8 mm in ZTD can be achieved after an initialization process of approximately 9 minutes, which supports the application of multi-GNSS observations and ambiguity resolution for RT meteorological applications.

It is anticipated that the performance of real-time (RT) GNSS meteorology can be further improved by incorporating observations from multiple Global Navigation Satellite System (GNSS), including GPS, GLONASS, Galileo, and BeiDou. In this paper, an operational RT system for extracting zenith troposphere delay (ZTD) using a modified version of the Precise Point Positioning With Integer and Zero-difference Ambiguity Resolution Demonstrator (PPP-WIZARD) was established. GNSS, including GPS, GLONASS, and Galileo, observation streams were processed using RT Precise Point Positioning (PPP) strategy based on RT satellite orbit/clock products from the Centre National d'Etudes Spatiales. An experiment covering 30 days was conducted, in which the observation streams of 20 globally distributed stations were processed. The initialization time and accuracy of the RT troposphere results using single-system and multisystem observations were evaluated. The effect of PPP ambiguity resolution was also evaluated. Results reveal that RT troposphere estimates based on single-system observations can both be applied in weather nowcasting, in which the GPS-only solution is better than the GLONASS-only solution. The performance can also be improved by PPP ambiguity resolution and utilizing GNSS observations. Specifically, we notice that ambiguity resolution is more effective in improving the accuracy of ZTD, whereas the initialization process can be better accelerated by GNSS observations. Combining all techniques, the RT troposphere results with an average accuracy of about 8 mm in ZTD can be achieved after an initialization process of approximately 8.5 min, which demonstrates superior results for applying GNSS observations and ambiguity resolution for RT meteorological applications.

In the traditional mode, re-initialization in real time kinematic PPP caused by problems such as signal interruption can seriously affect PPP's performance. An improved method is proposed in this paper to solve this problem. Firstly, an ionospheric predicting model and its relevant weighting method are designed. Then floating results of cycle slips are estimated by combining the predicted values and epoch/satellite differenced observations. After that, cycle slip fixing is attempted to achieve instantaneous re-initialization of PPP. Through adaptively adjusting the weighting of the ionospheric prediction results, the accuracy of the estimated parameters is improved, together with the success rate and reliability of cycle slip fixing. Analysis results from different distributions and different epochs reveal that the performance of cycle slip fixing is strongly correlated with station position, solar activity and time latency. Using the proposed method, a success rate of higher than 90% can be obtained when the time latency is relatively small (

In this work, soybean lipoxygenase enzyme was immobilized on the magnetic Fe3O4 nanoparticles to oxidate chlorpromazine (CPZ). The physicochemical properties of the nanoparticles were characterized with transmission electronic microscopy (TEM), fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermal gravimetric analysis (TGA), and the magnetic properties were detected by a vibrating sample magnetometer (VSM). The TEM images indicated the surface and the size of the immobilized enzyme were much rougher and thicker than those of the naked particles. The analyses of XRD patterns showed that the structure of the magnetic nanoparticles had no significant change while the nanoparticles also exhibited higher superparamagnetism at room temperature. Compared to free enzyme or the enzyme immobilized with other methods, the optimal pH, temperature and H2O2 concentration for the activity of immobilized enzyme did not have great changes, but the immobilized enzyme was more stable and less sensitive to the change of the influence factors than free counterpart. The immobilized enzyme could be recovered easily by magnetic separation and could be reused for many times in the process of CPZ oxidation. The results obtained by simulating the model of Michaelis-Menten indicated that the reaction of CPZ oxidation followed Michaelis-Menten kinetics and the enzyme still retained its affinity for CPZ while the enzyme was immobilized.