Ultra-thin heat pipes have been employed extensively for the thermal management of electronic devices. Their capacity for heat transfer is significantly influenced by the capillary performance of the wicking structure in the pipes. In this study, superhydrophilic (SHPi) and superhydrophobic (SHPo) background surfaces were prepared on aluminum sheets using a nanosecond fiber laser. SHPi grooves with widths ranging from 0.1 to 0.4 mm were then produced on the surfaces with the same laser. The effects of the background wettability on the capillary performance of the grooves were investigated. The fastest ascent of the water in the grooves on the SHPo background surface occurred when the groove widths were between 0.1 and 0.2 mm. As the groove width increased to 0.3–0.4 mm, the water level rose most quickly in the groove on the SHPi surface. Furthermore, water absorption was always larger on the SHPi background surface for grooves of the same width as on the other two surfaces. As a result, a wettable background surface that matches the application requirements should be selected. The SHPo background surface should be used when a rapid water rise in the groove is desired. The SHPi background surface, on the other hand, increases water absorption capacity. Water absorption achieved a maximum of 6.8 mg with a groove width of 0.4 mm, and capillary performance parameters reached 4.62 × 10 –7 N, which was 117.9% higher than the pristine background surface. This study presents fresh suggestions for increasing the capillary performance of vertically grooved wicks.

In this study, two superhydrophobic blade surfaces of propellers were prepared using nanosecond laser processing and superhydrophobic coating. Numerical calculations of the open water characteristics indicated that superhydrophobic propellers provide higher efficiency over the entire range of operating conditions. Towing tank tests showed that superhydrophobic propellers generate greater thrust but require more torque from an advanced coefficient of 0.3. The increased thrust was caused by the increased pressure differential between the pressure and suction sides. The change in torque was mainly attributed to the gradual loss of the air layer and the increased shape resistance of the rough structure. Within an advance coefficient of 0.3, the laser-processed superhydrophobic propeller exhibited a more apparent drag reduction effect, and the efficiency was improved by a maximum of approximately 2.8%. In contrast, the propeller with superhydrophobic coating has a stable drag reduction effect owing to the stable air layer on its surface during the entire testing process, with an average efficiency improvement of approximately 2.0%. The results confirmed that the superhydrophobic surface, especially the rough structure, significantly affected propeller efficiency. This research extends the practical engineering applications of superhydrophobic surfaces in vessel propulsion.

This article demonstrates the loss and recovery in hydrophobicity of silicone rubber insulator surface processed by a femtosecond laser. The two stages of the wettability conversion were investigated. First, a rough micro/nano structure was formed on the original hydrophobic sample surface processed by the femtosecond laser, and the water contact angle on the surface was reduced from similar to 110 degrees to a minimum of similar to 35 degrees. This hydrophilicity loss was due to the increase in the hydrophilic -OH groups and the reduction of the hydrophobic -CH3 groups on the surfaces. Second, the roughened samples were stored in a natural ambient environment. Over a certain storage time, the surface hydrophobicity recovered gradually and evolved into a superhydrophobic state. It was found that the migration of low molecular weight cycle and/or linear siloxane oligomers resulted in the recovery of the hydrophobicity property. Coupled with the increase of surface roughness caused by laser irradiation, the further evolution of the hydrophobicity was promoted. Moreover, the higher temperature accelerates the recovery of the surface hydrophobicity. The research on the conversion mechanism of the wettability on the silicone rubber insulator surface processed by femtosecond laser is of great significance for improving its reliability in practical applications.

In this paper, hydrophobic/superhydrophobic silicone rubber surfaces with disordered structures were prepared with a nanosecond laser. The fractal characteristic of the surfaces was also investigated. The results show that the fractal structures on the processed silicone rubber surface can roughly reflect the increasing trend of its hydrophobicity. More specifically, the air content in the liquid-solid contact area was found to be related to the surface superhydrophobicity. The solid fraction of superhydrophobic surfaces at close to 0.22 produced with different laser pulse widths can be used to identify whether such surfaces are in the superhydrophobic state after the laser treatment. In addition, the fractal parameters and gas/solid fraction could be used to predict the contact angles of surfaces in Wenzel and Cassie-Baxter states based on the fractal wetting equations. However, it is noted that with the increase of the laser fluence, the silicone rubber surfaces enter into a mixed state where the Wenzel and Cassie-Baxter states coexist. This paper provides a new method to characterize the wettability of the surfaces with the disordered microstructures.

The aging characteristics of laser-treated superhydrophobic silicone rubber surfaces was investigated through accelerated aging tests. It indicated that the superhydrophobic surfaces have excellent anti-aging properties, which is manifested in that even after aging for 1000 h, the contact angles of the superhydrophobic surfaces remain above 140 degrees. The loss of hydrophobicity was caused by defects in the surface microstructures, a decrease in the hydrophobic -CH3 groups, and an increase in the hydrophilic -OH groups on the surfaces. To avoid the decrease in the hydrophobicity of the prepared superhydrophobic surface, a simple and efficient heat treatment method was adopted to restore its hydrophobicity. After heat treatment at 200 degrees C, the rolling angle of the aged surface was restored to 4.6 degrees with a contact angle of 161.5 degrees. This recovery is mainly attributed to the decrease in the content of the -OH on the rubber surface during the heat treatment. The results also show the sample surface irradiated with a laser fluence of 10.0 J/cm(2) has better anti-aging performance and self-healing properties due to the larger particles and a more distinct micro-nano hierarchical structures, providing a smaller actual illumination area and a larger heating area in the aging and heat treatment process. (C) 2021 Elsevier Ltd. All rights reserved.

The purpose of this study was to relate the 1-year risk of death and development of acute myocardial infarction among diabetics with acute chest pain to whether they had a history of hypertension or not. All patients with a history of diabetes mellitus who, during 21 months, were admitted to the Emergency Room in Sahlgrenska Hospital, Goteborg, due to chest pain or other symptoms suggestive of acute myocardial infarction, were included. Among the 427 patients with a history of diabetes mellitus 44% also had a history of hypertension. These hypertensives had a 1-year mortality rate of 22% as compared with 26% in diabetics without such a history (p > 0.2). The corresponding values for development of myocardial infarction during 1 year were 33 and 30%, respectively (p > 0.2). We did not find a history of hypertension to adversely affect the prognosis among diabetics with acute chest pain.

In this paper, the superhydrophobic surfaces of silicone rubber with different microstructure were directly prepared by texturing with a nanosecond fibre laser. The superhydrophobic surfaces have excellent anti-icing performance. Even at 0 degrees C, the superhydrophobic surface has a contact angle of similar to 150 degrees and a rolling-off angle of similar to 2.5 degrees. The superhydrophobic silicone rubber surfaces with different microstructures have obvious differences in contact behaviours with water droplets at low temperatures. The surface textured with a laser fluence of 10 J cm(-2) has a larger particle size and more abundant micro-nano particles, which results in a smaller contact area with the water droplet due to greater roughness and root mean square slope. The deeper the small gaps on the superhydrophobic surface, the more time it takes for the change in contact state between the surface and the water droplets. The adhesion strength of the superhydrophobic rubber surfaces with the ice layer were smaller due to the air stored between the surfaces and the ice layer. In particular, the laser textured surface with an laser fluence of 10 J cm(-2) has the lowest ice adhesion strength due to its layered micro-nano composite structure. After 30 cycles of icing and de-icing, the processed silicone rubber surface still retains excellent hydrophobicity. The superhydrophobic silicone rubber surface has important value in anti-icing and anti-pollution applications.

The current demand for oil/water separation with an efficient, cost-effective, and environmentally friendly method is increasing. A laser-structured superhydrophobic/superoleophilic aluminum was prepared by using a nanosecond laser. The aluminum plate was used for oil/water separation without external force, which can replace the traditional porous materials. The effect of hole diameter and spacing on the effectiveness of oil/water separation is discussed. The results show that the aluminum plate with a hole size of 0.5 mm can be considered a more appropriate choice for the oil/water mixtures with large water content. In addition, complete separation of oil and water can be achieved in the hole spacing range of 1.0–3.0 mm. The oil separation speed can be increased without changing the water permeability by reducing the hole spacing, which is positively related to the hole spacing. Separation efficiencies were tested with various oil/water mixtures. The aluminum plate with a hole size of 0.5 mm can quickly separate the different oil mixtures with less than 50% oil content while achieving an oil separation efficiency of up to 99%. Due to the difference in dynamic viscosity of various oil phases, the separation efficiencies of the petrol, kerosene, and diesel are slightly different but can still be maintained above 99%. The laser-processed aluminum plate has several advantages of high porosity, high surface of superhydrophobic properties, and easy tunable structures. In practical applications, the hole size and the spacing should be appropriately adjusted according to specific conditions, such as different oils, the mixing ratios, etc., to obtain the best separation efficiency and speed.

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Purpose The original powder commonly used for laser 3D printing is atomized alloy powder. The purpose of this study is to investigate the effect of ball milling (BM) on the structure and performances of the alloy powder and its composite products. Design/methodology/approach BM powder of Ni-Cr-graphite elements was subjected to laser cladding forming and the effect of BM on the powder structure was studied by X-ray diffraction, metallographic microscopy and scanning electron microscopy. The laser cladding-formed coatings were also tested by reciprocating friction measures and electrochemical corrosion experiment. Findings The results showed that the grains of laser cladding-formed Cr3C2-NiCr coating of BM powder were more refined compared to the coating of the atomized powder. Moreover, the abrasion resistance and corrosion resistance were slightly improved. Originality/value This work offers guidance for new original powder selection for laser 3D printing/powder bed forming/selective laser melting applications.

In this era of technological disruption, when many industries are fighting to stay relevant, the oil and gas industry seems to be stagnant. It is in this environment where public perception of the modern industry is becoming more critical and as younger consumers grow in both number and political influence, their viewpoints will become especially vital to the continued relevance of the industry. The oil and gas industry gives itself high marks for innovation, safety and environmental sustainability, and yet the public opinion in these areas is often portrayed very negatively. We have an image problem. The belief that oil and gas is good for society seems to decline with each younger generation. The public believes the industry is necessary for society, though they still see it as a problem causer, not a problem solver. But support for the industry falls with each generation and millennials are more likely to believe the industry is bad for society and a problem causer. The oil and gas industry needs to communicate and engage with consumers to identify ways to better understand their motivations and concerns. Clearly there is a gap in how the public and executives view the industry and the time to address these perceptions is now. To view the video, click the link on the right.

This research demonstrates that groundwater contaminated by a relatively dilute but persistent concentration of 1,4-dioxane (1,4-D), approximately 60 mu g/L, and chlorinated aliphatic co-contaminants (1.4 to 10 mu g/L) can be efficiently and reliably treated by in situ aerobic cometabolic biodegradation (ACB). A field trial lasting 265 days was conducted at Operable Unit D at the former McClellan Air Force Base and involved establishing an in situ ACB reactor through amending recirculated groundwater with propane and oxygen. The stimulated indigenous microbial population was able to consistently degrade 1,4-D to below 3 mu g/L while the co-contaminants trichloroethene (TCE) and 1,2-dichloroethane (1,2-DCA) were decreased to below 1 mu g/L and 0.18 mu g/L, respectively. A stable treatment efficiency of more than 95% removal for 1,4-D and 1,2-DCA and of more than 90% removal for TCE was achieved. High treatment efficiencies for 1,4-D and all co-contaminants were sustained even without propane and oxygen addition for a 2-week period.

It is of great significance to study the surface wettability of cemented carbide tools for the improvement of tool life and processing surface quality. Micro-pits arrays on the YG3 surface were fabricated by nanosecond pulsed laser with a wavelength of 1064 nm. The optical microscope, optical profiler and contact angle measurement were used to measure the surface morphology and contact angle. The influence of surface morphology on contact angle under different laser average power, scanning times and micro-pits spacing were investigated. Based on Wenzel's theory, the geometrical morphology model of micro-pits was established to analyze the influence mechanism of surface morphology on contact angle. Results show that the diameter and depth of micro-pits increase as the laser average power or scanning times increase. The micro-pits distribution density increases with decreasing micro-pits spacing. Under three conditions, all the surface roughness ratios increase. The cosine contact angle is positively related to the roughness ratio and the variation trends are basically consistent. As a result, the contact angle decreases with the increase of roughness ratio. The actual contact angle equation is fitted using the variation curves of actual contact angle versus derivation contact angle.

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This paper demonstrates laser surface modification of silicone rubber using an economic and efficient nanosecond fibre laser. The resulting surface morphology shows that micro-nano structures leading to an increase in the surface slope were formed after processing. The effect of laser power on the surface wettability was investigated demonstrating that the contact angle of the silicone rubber surface increased with increasing laser fluence. The water contact angle on the treated surface reached similar to 160 degrees with a rolling-off angle of similar to 3 degrees when the laser fluence reached 10 J cm(-2). After laser processing, both the roughness and root mean square slope of the silicone rubber surface increased with increasing fluence and reached maximum at a fluence of 10 J cm(-2). An analysis of the pre- and post processing surfaces suggested there were no significant compositional changes, but there were some micro-structural changes to the polymer chain, namely, cleavage of the Si-O-Si bonds. It is thus proposed that the hierarchical micro-nano structures and hence the change in the root mean square slope of the silicone rubber surface induced by laser irradiation are the primary reasons for its superhydrophobicity. The preparation of superhydrophobic silicone rubber can have important applications in self-cleaning, anti-icing, and anti-pollution.

One method to fabricate super-hydrophobic aluminum surfaces by using nanosecond fiber lasers is proposed. After the laser-processed samples are baked, a series of aluminum surfaces with different wetting properties are obtained. A super-hydrophobic surface can be obtained by increasing the laser fluence. The study results show that, with the increase of laser fluence, not only the aluminum surface roughness increases, but also a clear micro-nano two-level structure is formatted. The area ratio between air and the total area of the superhydrophobic aluminum composite contact surface is 90％.The super-hydrophobic surface induced by nanosecond laser is attributed to the coaction of micro-nano structures and chemical compositions.

With the development of femtosecond laser technology and wide applications of polymethyl methacrylate (PMMA),the research on optical properties of PMMA has become a hot spot.Filamentation phenomenon appears in the process of transparent materials by femtosecond laser.Generation principles of self-focusing and filamentous are analyzed.One of the most important characteristics of laser beam is polarization state.Linearly polarized light,circularly polarized light,radially polarized light and angularly polarized light can be controlled by the combination of spatial light modulator,1/2 wave plate and 1/4 wave plate.Generated polarized light with energy of 1 μJ is used in the line processing on PMMA,and then the comparative analysis is conduct on the length and initial position of filamentation under different polarized light.Experimental results show that linearly polarized light and circularly polarized light result in filamentation with short length,and filamentation position of linearly polarized light is close to the incident plane.Radially polarized light and azimuthally polarized light result in long length,and the distance of filamentation position to the incident plane is long.

The surface contact angles of aluminum-based materials is regulated and controlled by using femtosecond laser pulses with different energies, and the transformation mechanism of wettability is analyzed and studied. The results show that the final stable wettability state of aluminum-based material surfaces after the femtosecond laser processing and aging treatment is related to the laser energy and the aging time. With the increase of the laser energy, the surface contact angle is changed from 70°to above 150°. The morphology, roughness and chemical compositions of aluminum-based surfaces are studied under different pulse energy processing conditions. The results show that the wettability of a laser-processed sample changes from a hydrophilic state to a final super-hydrophobic state. The super-hydrophobic surfaces can be obtained in different pulse energy regions, but there are non-periodic or periodic structural differences in their surface microstructures, and the formation mechanisms of hydrophobic properties are different.

The effects of pulse energy and spot overlap ratio on the wettability of ceramic tools processed by femtosecond lasers are investigated. The wettability of the alumina ceramic tools after laser treatment is investigated by measuring the contact angles. The experimental results show that the femtosecond laser can change the wettability of ceramic material surfaces. The superhydrophilic surfaces and the superhydrophilic-based cutting fluid surfaces can be prepared if suitable laser energy density and spot overlap ratio are chosen. The wetting speed of water based cutting fluid on the laser-processed surfaces is exponentially decaying with the contact angle.