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Substrate temperature affects the volatilization rate of solvents, and thus changes the morphology and the crystallization process of perovskite layers.

The current research on self-resonating cavitating waterjet(SRCW) mainly focuses on the generation mechanism and structure optimization. Researches relating to the influences of disturbances at nozzle inlet on the characteristics of the jet are rarely available. In order to further improve the performance of SRCW, effects of area discontinuity(enlargement and contraction) are experimentally investigated using three organ-pipe nozzles. Axial pressure oscillation peak and amplitude as well as aggressive erosion intensity of the jet are used to evaluate the effects. The results reveal that area enlargement and contraction affect the peak differently, depending on the inlet pressure, nozzle geometry, and standoff distance; while area contraction always improves the amplitude regardless of these factors. At inlet pressures of 10 MPa and 20 MPa, area discontinuity improves the peak at almost all the testing standoff distances, while this only happens at smaller standoff distances with the inlet pressure increased to 30 MPa. The capability of area discontinuity for improving the amplitude is enhancing with increasing inlet pressure. Moreover, the cavitation erosion ability of the jet can be largely enhanced around the optimum standoff distance, depending on the type of area discontinuity and nozzle geometry. A preliminary analysis of the influence of area discontinuity on the disturbance waves in the flow is also performed. The proposed research provides a new method for effectively enhancing the performance of SRCW.

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Through a controllable "reactivate" "graft" synthetic route, two asymmetrical "Janus" dendronized polymers (DPs) were successfully synthesized. Dendrons were grafted to a linear polymer motherboard by a story-by-story construction method. Due to the heterogenetic "Janus" structure, with orderly arranged chromophore moieties, the polymers demonstrated extremely large second-order nonlinear optical (NLO) coefficients and excellent NLO thermal stability. DP-4l and DP-6l had high d 33 values of 232 and 227 pm/V, respectively, which reached the highest value reported so far for linear-based polymers containing simple azo-chromophore moieties. The controllable synthesis sheds light on the structure-property relationships of NLO polymers and other dendronized-structure functional polymers.

Self-resonating waterjets (SRWJs) are being widely used in the fields of energy exploitation, due to the significantly increased penetration rate of roller bits in deep-hole drilling. To further improve the impact and erosion abilities of SRWJs, the effects of the downstream contraction ratio of organ-pipe nozzle on the axial pressure oscillations were experimentally studied. The axial pressure oscillation peak and amplitude were used to evaluate the effects under two inlet pressures and various standoff distances. The results show that the downstream contraction ratio can affect the development trends of the pressure oscillations and determines the values of the peaks and amplitudes. Under the experimental conditions, 2.5 is the ratio that leads to the maximum peaks and amplitudes at almost all the testing standoff distances, while the ratio of 2 always results in the minimum ones. The development trend of the pressure oscillation peak for the ratio of 3.5 has a great change at an inlet pressure of 20 MPa. Generally, the relative pressure oscillations are more violent at an inlet pressure of 10 MPa, which is regardless of the contraction ratio. This study helps provide a guideline for determining the physical parameters required in the fabrication of organ-pipe nozzles used for deep-hole drilling.

High-speed waterjet peening technology has attracted a lot of interest and is now being widely studied due to its great ability to strengthen metal surfaces. In order to further improve the mechanical properties of metals, self-excited oscillation pulsed waterjets (SOPWs) were used for surface peening with an experimental investigation focused on the surface topography and properties. By impinging the aluminum alloy (5052) specimens with SOPWs issuing from an organ-pipe oscillation nozzle, the hardness and roughness at various inlet pressures and stand-off distances were measured and analyzed, as well as the residual stress. Under the condition of optimum stand-off distances, the microscopic appearances of peened specimens obtained by SEM were displayed and analyzed. Results show that self-excited oscillation pulsed waterjet peening (SOPWP) is capable of improving the surface quality. More specifically, compared with an untreated surface, the hardness and residual stress of the peened surfaces were increased by 61.69% and 148%, respectively. There exists an optimal stand-off distance and operating pressure for creating the highest surface quality. SOPWP can produce almost the same enhancement effect as shot peening and lead to a lower surface roughness. Although such an approach is empirical and qualitative in nature, this procedure also generated information of value in guiding future theoretical and experimental work on the application of SOPWP in the industry practice.

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