Search

High heat generation is the main problem that sophisticated electronic devices can suffer. The pool boiling process can offer an excellent heat dispassion at constant temperatures. Therefore, it is one of the most powerful cooling processes used in nuclear power plants, data centers, air conditioning, etc. Because of that, enhancing pool boiling has become a goal of many recent investigations. The current paper presents an experimental study to evaluate the effect of nano and nanocomposite coating on the performance of pool boiling of deionized water under atmospheric pressure. Four surfaces made of copper were used in this study: smooth, CNT (1 g), GNPs (1 g), and (CNT-GNPs (1:1) g) surfaces. A four-step electro-deposition method was used to fabricate a nickel coating using the abovementioned materials. The variation in coating materials offers different surface wettability and roughness to the fabricated surfaces. The experiment's outcome revealed that the hydrophilic material can enhance the critical heat flux (CHF). The mixed wettability obtained by the nanocomposite coating can improve the heat transfer coefficient (HTC). Maximum enhancement in the CHF is obtained by GNPs (1 g) surface with 102%, while the maximum HTC is obtained by (CNT-GNPs (1:1) g) surface with 154% when it is compared with the plain surface.

In this work, a simple and one-step process was demonstrated to develop hydrophobic polymer surfaces. Commercially available polycarbonate (PC) was treated to turn the front surface hydrophobic with an average wetting contact angle (WCA) as high as 110.5°. The formation of micro-flowers with a coverage density of 9.29 × 106/cm2 on the top of fine base nanostructures was confirmed by a high-resolution field emission scanning electron microscope (FESEM). Impact of typical metal and metal oxide such as silver (Ag) and tungsten oxide (WO3) deposited on such hydrophobic surfaces was demonstrated. Petals of micro-flowers and fine base nanostructures were well decorated with functional metals such as Ag and thus the front surface remained hydrophobic with an average WCA as high as 106.6°. Abundant sharp spikes on the top of narrow hills and dips as revealed in the high-resolution FESEM investigation, were speculated to be the reason behind this hydrophobic characteristic. On the other hand, the hydrophobic surface (WCA of ∼ 110.5°) turned hydrophilic (WCA of ∼11.7°) when the surface was decorated with functional metal oxides, such as WO3. Sessile drop tests were carried out to record average WCA and to understand the wetting characteristics of the specimens. A plausible mechanism for such hydrophobic characteristics as well as the transition from a hydrophobic state to a hydrophilic state has been elucidated.

The effect of biphilic surfaces on subcooled flow boiling in a horizontal rectangular duct was investigated. Biphilic surfaces were created on an aluminum alloy substrate in the form of juxtaposed Hydrophobic (HPo) and Hydrophilic (HPi) transverse strips. In this regard, two different testing samples with strip widths of 10 and 18 mm were prepared, named pattern I and pattern II, respectively. Using Deionized Water (DIW), the experiments were performed with the two mentioned biphilic patterns and a plain surface. Finally, different cases were compared, and the results were interpreted. The results showed that the biphilic surfaces improve the Heat Transfer Coefficient (HTC) and cause boiling to be initiated at a lower wall temperature. In this regard, pattern I and pattern II represent 22 and 40% improvement in HTC, and boiling initiates 31 and 33.5 °C sooner compared to the plain surface, respectively. In addition, the experiments were also conducted with an Ethylene Glycol/Water mixture (EG/W) in the same manner. The results revealed that EG/W represents smaller HTC values for all cases and shifts the boiling points to higher wall temperatures compared to DIW. It is worth mentioning that the major amount of this HTC reduction is occurred in the single-phase area, in lower wall temperatures. [ABSTRACT FROM AUTHOR]

Rubber particles have good energy absorption and deformation ability. The incorporation of rubber particles into cement base can effectively improve the toughness of the material, and enhance the freezing resistance, cracking resistance, impact resistance and other properties of cement base. However, because rubber particles are a kind of hydrophobic substance, the interface bonding force between rubber and cement slurry is weak, and the strength of cement-based materials is decreased. Therefore, chemical and physical modification of rubber cement-based materials is studied. The results show that the modified rubber can enhance the properties of cement-based materials in two ways. First, the modifier can improve the hydrophilic of rubber by dissolving the impurities on the surface of rubber particles and forming a film on the surface. Second, the modifier reacts with the hydration product to form an effective chemical cross-link, so that the rubber particles form a close connection with the cement slurry. At the same time, it is found that rubber particles and fiber polymers have synergistic effect on the strengthening and toughening of cement-based materials. [ABSTRACT FROM AUTHOR]

In this study, the heat transfer performance of a two-phase closed thermosyphon with super-hydrophobic (SH-phobic) condenser and super-hydrophilic (SH-philic) evaporator is investigated, and the results are compared with those of a bare condenser. At 100–200 W, the total thermal resistance on the SH-phobic surface decreases by up to 10.40 %, 0.41 % and 27.44 % compared with the bare condenser surface at filling ratios of 0.25, 0.5, and 0.75, respectively. However, the total thermal resistance increases by 55.06 %, 411.35 % and 128.33 % from 300 to 400 W, respectively. The critical heat flux for the SH-phobic surface is lower than for the bare surface. The SH-phobic surface performs better than bare surface in the low-power region (100–200 W), but not in the high-power region above 300 W. Therefore, the input power should be considered when applying the SH-phobic surface to the condensing section. [ABSTRACT FROM AUTHOR]

Abstract The stability of soil organic matter (SOM) that governs soil organic carbon (SOC) storage depends on its characteristics and components, but little is known about how tree species in forest ecosystems affect SOM components and characteristics. In this study, we used FTIR spectroscopy to investigate plantations of two ecologically and economically significant tree species—namely, spruce (Picea spp.) and sycamore (Acer pseudoplatanus)—in order to determine how the different litter inputs and root-microbe interactions of these two plantations affect the functional groups, components, and characteristics of their SOM. Soil samples were taken from the topsoil (0–10 cm) and subsoil (10–20 cm). In the 0–10 cm soil depth, the SOM's hydrophilic, hydrophobic, and aromatic components differ between the spruce and sycamore plantations. The hydrophobic components constitute the primary constituents of the SOM of the two forest plantations, in contrast to the expected predominance of the hydrophilic component of the SOM. Also, the high hydrophobicity (hydrophilic/hydrophobic) in the subsoil of the spruce plantations was attributed to a decrease in hydrophilic components and a subsequent increase in hydrophobic components of the SOM. The sycamore plantations exhibited a higher SOM aromaticity and a greater degree of decomposition than the spruce plantations. The aforementioned distinctions emphasise the contrasting mechanisms involved in transforming and turnover of the two-tree species' soil organic matter (SOM).

Wetting functionalities of rough surfaces are largely determined by the Laplace pressure generated across liquid–gas interfaces formed within surface structures. Typically, rough wetting surfaces create negative Laplace pressures, enabling capillary wicking, while rough non-wetting surfaces create positive Laplace pressures, exhibiting fluid repellency. Here, with microfabricated reentrant structures, it is shown that the same surface can exhibit either a negative or positive Laplace pressure, regardless of its intrinsic wettability. This material-independent Laplace pressure duality enables or enhances a range of wetting functionalities including wicking, switchability, and selectivity. On the same surface, capillary rise, capillary dip, and the combination of the two which leads to further enhancement of the total sustainable capillary height and Laplace pressure, the driving force for wicking is demonstrated. Further, active switching of wetting states between the hemiwicking and the repellent Cassie state on reentrant structures is shown. Moreover, with a water-hexane mixture system, selective wetting of reentrant structures are demonstrated, that is, water can be selectively wicked or repelled in the presence of hexane, and vice versa. These functionalities are achieved, which would typically require complex chemical coatings, solely using surface structures, thus largely expanding the design space for a wide range of thermofluidic applications.

Aluminum alloy 2024 is the most widely used metal alloy in aircraft due to its superior characteristics. Although the effects of surface chemistry and topography on the wettability transition have been investigated in the literature, it has not yet been clarified which mechanism is more dominant. In this study, the super-hydrophobic Al2024 sample surfaces were obtained over time in a single step using a nanosecond pulsed fiber laser. Different micro- and nano-structures were produced by changing the laser output power and scanning speed. The effects of laser parameters on the wettability of the Al2024 samples were examined. As with the untreated sample, all fresh laser-treated samples have a hydrophilic or super-hydrophilic surface property. It was found that the fresh laser-treated aluminum alloy surfaces were super-hydrophilic. Then, the Al2024 samples were exposed to ambient air for a certain period. It was found that the contact angles (CAs) of all laser-treated Al2024 samples increased over time. Also, the water drop moved away from the surface of some super-hydrophobic samples at angles of less than 10°. With more than 150° water contact angle and less than 10° sliding angle, it was proved that the lotus effect was obtained at various time scales. The icing properties of the lotus sample were investigated. The surface icing characteristics of the lotus sample have been improved. The XPS high resolution analyses show that the Al-C bond could be responsible for the wettability transition of the laser-ablated samples from hydrophilic to super-hydrophobicity (lotus). [ABSTRACT FROM AUTHOR]

The stability of soil organic matter (SOM) that governs soil organic carbon (SOC) storage depends on its characteristics and components, but little is known about how tree species in forest ecosystems affect SOM components and characteristics. In this study, we used FTIR spectroscopy to investigate plantations of two ecologically and economically significant tree species—namely, spruce (Picea spp.) and sycamore (Acer pseudoplatanus)—in order to determine how the different litter inputs and root-microbe interactions of these two plantations affect the functional groups, components, and characteristics of their SOM. Soil samples were taken from the topsoil (0–10 cm) and subsoil (10–20 cm). In the 0–10 cm soil depth, the SOM's hydrophilic, hydrophobic, and aromatic components differ between the spruce and sycamore plantations. The hydrophobic components constitute the primary constituents of the SOM of the two forest plantations, in contrast to the expected predominance of the hydrophilic component of the SOM. Also, the high hydrophobicity (hydrophilic/hydrophobic) in the subsoil of the spruce plantations was attributed to a decrease in hydrophilic components and a subsequent increase in hydrophobic components of the SOM. The sycamore plantations exhibited a higher SOM aromaticity and a greater degree of decomposition than the spruce plantations. The aforementioned distinctions emphasise the contrasting mechanisms involved in transforming and turnover of the two-tree species' soil organic matter (SOM). [ABSTRACT FROM AUTHOR]

Blood-contacting medical devices often succumb to thrombosis, limiting their durability and safety in clinical applications. Thrombosis is fundamentally initiated by the nonspecific adsorption of proteins to the material surface, which is strongly governed by thermodynamic factors established by the nature of the interaction between the material surface, surrounding water molecules, and the protein itself. Along these lines, different surface materials (such as polymeric, metallic, ceramic, or composite) induce different entropic and enthalpic changes at the surface–protein interface, with material wettability significantly impacting this behavior. Consequently, protein adsorption on medical devices can be modulated by altering their wettability and surface energy. A plethora of polymeric coating modifications have been utilized for this purpose; hydrophobic modifications may promote or inhibit protein adsorption determined by van der Waals forces, while hydrophilic materials achieve this by mainly relying on hydrogen bonding, or unbalanced/balanced electrostatic interactions. This review offers a cohesive understanding of the thermodynamics governing these phenomena, to specifically aid in the design and selection of hemocompatible polymeric coatings for biomedical applications. Blood-contacting medical devices often succumb to thrombosis, limiting their durability and safety in clinical applications. A plethora of polymeric coating modifications have been utilized for addressing this issue. This review offers a cohesive understanding of the thermodynamics governing these phenomena, to specifically aid in the design and selection of hemocompatible polymeric coatings for biomedical applications. [Display omitted] [ABSTRACT FROM AUTHOR]

The accumulation of microorganisms, algae, mussels, and barnacles on the hull of sea vessels leads to biofouling, surface corrosion, and increased drag as the vessel moves through water costing the marine industry around $15 billion/year. Current commercial traditional antifouling coatings suffer from reduced energy efficiency and short lifespan and contain heavy metals that are toxic to marine organisms and humans. The banning of these coatings is due to environmental concerns, and nonbiocidal alternatives such as polymer-based coatings are being sought after. This review demonstrates emerging promises of hydrogel fouling-release coatings (FRCs) in the marine environment that may be effective against a prevalent amount of biofouling agents. The review also highlights the importance of polymer backbone materials with surface wettability characteristics possessing hydrophobic, hydrophilic, and zwitterionic properties and further discusses emerging antifouling techniques, synthesis of hydrogel, swelling behavior of hydrogel, laboratory assays of hydrogel coating, marine field test, and outlook of hydrogel fouling-release (FRCs) coatings. [ABSTRACT FROM AUTHOR]

The present studies shed light on the continuum breakdown of water confined in nanotubes of different materials and diameters. The structure and hydrodynamics of water confined in nanotubes of carbon (CNT), boron nitride (BNNT), silicon carbide (SiC), and silicon nitride (SiNT) of different chirality indices were analyzed to examine the potential nanomembrane material for water purification. According to our findings of the contact angle with water, BNNTs are more hydrophobic than CNTs, and silica nanotubes are hydrophilic. The higher permeability of water was observed through CNTs and BNNTs in comparison to silica nanotubes. Nearly flat velocity profiles indicated continuum breakdown at the nanoscale. Also, the trend for viscosity and diffusion coefficient did not follow the Stokes–Einstein relation, indicating continuum breakdown. The results demonstrated the connectivity of microscopic diffusion with the macroscopic permeation flux, which might be important information for the theoretical investigation of the suitable operational regime in reverse osmosis. Essentially, the continuum breakdown due to freezing of water was seen to be diminished with an increase in temperature. The results showed characteristic changes in the density profile, diffusion coefficient, velocity autocorrelation functions, density of state functions, and thermodynamic entropic components (evaluated using the two-phase thermodynamic method) of permeating water molecules. Importantly, our results reflect that the continuum breakdown observed for water confined in smaller nanotubes is true only at temperatures below 400 K due to the ice-like dense structure of water molecules. Once the entering water molecules can gain energy to compensate for the loss of H bonds, the conventional fluid dynamics relations can be well applied to estimate the hydrodynamics of confined water. [ABSTRACT FROM AUTHOR]

Surface functional groups (SFGs) play a key role in adsorption of any target molecule and CO2 is no exception. In fact, due to its quadrupole nature, different SFGs may attract either the oxygen or the carbon atoms to facilitate improved sorption characteristics in porous materials, hence the proliferation of this approach in the context of carbon capture via solid adsorbents. However, actual processes involve CO2 capture/removal from a mixed gas stream that may have a non-negligible water content. The presence of humidity significantly hampers the sorption properties of classical physisorbents. To overcome this, the surface of the adsorbent can be modified to include hydrophobic/hydrophilic SFGs making the materials more resilient to moisture. However, the mechanisms behind H2O-tolerance depend greatly on the characteristics of SFGs themselves. Herein, a multitude of hydrophobic and hydrophilic SFGs (e.g. carbonyls, halogens, hydroxyls, nitro groups, phenyls, various alkyl chains and etc.) for physical CO2 adsorption are reviewed within the context of their separation performance in a humid environment, highlighting their merits and limitations as well as their impact on cooperative or competitive H2O – CO2 adsorption.

Shrink film is a thin sheet of polystyrene plastic that shrinks to 25–40% of its original size when heated. This study investigated the shrinkage factor of the film at different temperatures and baking times to determine the optimal fabrication recipe for shrink film microfluidic device production. Additionally, this study characterized the properties of shrink film, including minimum possible feature size and cross-section geometries, using manual engraving and the CAMEO 4 automated cutting machine. The optimal shrinkage factor ranged from 1.7 to 2.9 at 150 °C and a baking time of 4 min, producing the ideal size for microfluidic device fabrication. The X- and Y-axes shrank ~2.5 times, while Z-axis thickened by a factor of ~5.8 times. This study achieved a minimum feature size of 200 microns, limited by the collapsing of channel sidewalls when shrunk, leading to blockages in the microchannel. These findings demonstrate the feasibility and versatility of using shrink film as a cost-effective and efficient material for the rapid fabrication of microfluidic devices. The potential applications of this material in various fields such as the medical and biomedical industries, bacteria and algae culture and enumeration are noteworthy. [ABSTRACT FROM AUTHOR]

An increase in population and rapid rise in water consumption has put the world's water supply in threat. Supplies of fresh water are depleting specifically in the arid regions. Considering the increasing need for clean water, it is necessary to develop efficient water harvesting methods. In this regard, this study provides an overview of the use of rain and fog water harvesting systems. These systems have attracted interest as potential sources of water due to their accessibility, affordability and ease of construction. Particularly, fog harvesting is an effective method in misty environments where collection of tiny airborne droplets, droplet fusion, conveyance, and storage are major processes. The outcomes of this study are helpful for upcoming researchers, water engineers, organizations, policymakers and governments to assist sustainable water management. [ABSTRACT FROM AUTHOR]

Copyright of Al-Nahrain Journal for Engineering Sciences is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Two lasers were utilized for silicon processing using photoelectrochemical etching and laser texturing in order to produce nano/micro structures, respectively. Photoelectrochemical etching process utilizes a CW diode laser of 532 nm wavelength was used to support electrochemical etching for both n-type and p-type conductivity. While laser texturing process was employed using pulsed fiber laser of 1064 nm wavelength. Various characterization methods were devoted to examine silicon micro/nanostructures surfaces produced by lasers. These methods include AFM, SEM and Raman scattering to provide clear evidence about formation of micro/nanostructures abundant at silicon surfaces. Moreover, FTIR analysis for the laser produced silicon surfaces could emphasize whether the resultant silicon surface is hydrophilic or hydrophobic. Image analysis software adopted a side view micro image was used to measure the contact angle between the water droplet and silicon micro/nano-surfaces. It is found that the laser produced silicon nanostructure by photoelectrochemical etching creates a hydrophobic surface and even super hydrophobic with contact angle of 130 degrees for 50 nm average size. In addition, utilizing fiber laser of high repetition rate for laser texturing produces microstructures that are super hydrophilic with contact angle could reach 8 degrees for a surface dimension of 50 μm.

In the past few decades, organic solvent nanofiltration (OSN) has attracted numerous researchers and broadly applied in various fields. Unlike conventional nanofiltration, OSN always faced a broad spectrum of solvents including polar solvents and non-polar solvents. Among those recently developed OSN membranes in lab-scale or widely used commercial membranes, researchers preferred to explore intrinsic materials or introduce nanomaterials into membranes to fabricate OSN membranes. However, the hydrophilicity of the membrane surface towards filtration performance was often ignored, which was the key factor in conventional aqueous nanofiltration. The influence of surface hydrophilicity on OSN performance was not studied systematically and thoroughly. Generally speaking, the hydrophilic OSN membranes performed well in the polar solvents while the hydrophobic OSN membranes work well in the non-polar solvent. Many review papers reviewed the basics, problems of the membranes, up-to-date studies, and applications at various levels. In this review, we have focused on the relationship between the surface hydrophilicity of OSN membranes and OSN performances. The history, theory, and mechanism of the OSN process were first recapped, followed by summarizing representative OSN research classified by surface hydrophilicity and types of membrane, which recent OSN research with its contact angles and filtration performance were listed. Finally, from the industrialization perspective, the application progress of hydrophilic and hydrophobic OSN membranes was introduced. We started with history and theory, presented many research and application cases of hydrophilic and hydrophobic OSN membranes, and discussed anticipated progress in the OSN field. Also, we pointed out some future research directions on the hydrophilicity of OSN membranes to deeply develop the effect made by membrane hydrophilicity on OSN performance for future considerations and stepping forward of the OSN industry.

This study investigates the use of a CuBr vapor nanosecond laser with a 510 nm/578.2 nm wavelength for the surface treatment of 1050 aluminum and 2219 aluminum alloys. Laser-induced periodic surface structuring was used to optimize processing parameters to achieve hydrophobic and hydrophilic properties on the surface. The wetting properties were measured and the roughness results (Ra, Rz, Rq) evaluated. Prior to and after laser treatment, surface wetting and roughness changes were investigated. The wetting study showed that the maximum contact angle between a droplet of deionized water and the treated surface can be reached between more than 140 degrees and less than 10 degrees, which, respectively, is a superhydrophobic and superhydrophilic surface. Compared with the untreated surface, wetting increased by more than 2 times and decreased by more than 8 times. Overall, experiments show the dependence of wetting properties on laser input parameters such as scan speed and scan line distance with different delivered energy amounts. This study demonstrates the possibility of laser parameter optimizations which do not require auxiliary gases and additional processing of the resulting surfaces to obtain different wetting properties on the surface. The findings described in this article suggest that the CuBr laser surface treatment method is a promising method for industrial applications where surfaces with special wetting and roughness properties are required, for example, the laser marking of the serial number of parts used in wet environments such as aerospace, shipbuilding, and defense industries. [ABSTRACT FROM AUTHOR]

To investigate the effect of relative humidity percentage on heat transfer and distribution of droplets in the condensation phenomenon, a test device with the ability to provide and control different environmental conditions was made, and therefore, the hydrophilic (copper) and hydrophobic (Teflon coating on copper) surfaces were measured under controlled environmental conditions. In all the tests, the inlet air flow rate, inlet air temperature, air temperature reaching the test surface, water temperature, water surface height, and test surface temperature were kept constant at specific values using PID control. Each test's relative humidity values of 80, 88, and 96% have been determined and controlled. The results of the transient investigation of heat transfer show that it takes time for the condensation phenomenon to occur, and the higher the surface hydrophilicity and relative humidity, the shorter this time will be. Also, the average heat transfer for 60 minutes was calculated. It showed that the average heat transfer coefficient increases with increasing humidity. Under the same environmental conditions, the heat transfer coefficient on hydrophilic surfaces is higher than on hydrophobic ones. In the graphical analysis of the droplet size, it has been observed that the most oversized droplets on hydrophilic surfaces at relative humidities of 88 and 96% are in the hydraulic diameter range of 0.35 to 0.4, and on hydrophobic surfaces are at relative humidities of 80 and 88% in the hydraulic diameter range of 0.2 to 0.25 mm. [ABSTRACT FROM AUTHOR]

Lung supportive devices (LSDs) have been extensively utilized in treating patients diagnosed with various respiratory disorders. However, these devices can cause moisture depletion in the upper airway by interfering with the natural lubrication and air conditioning process. To remedy this, current technologies implement heated humidification processes, which are bulky, costly, and nonfriendly. However, it has been demonstrated that in a breath cycle, the amount of water vapor in the exhaled air is of a similar quantity to the amount needed to humidify the inhaled air. This research proposes to trap the moisture from exhaled air and reuse it during inhalation by developing a state-of-the-art hydrophilic/hydrophobic polymer tuned to deliver this purpose. Using the atom transfer radical polymerization (ATRP) method, a substrate was successfully created by incorporating poly (N-isopropyl acrylamide) (PNIPAM) onto cotton. The fabricated material exhibited a water vapor release rate of 24.2 ± 1.054%/min at 32 °C, indicating its ability to humidify the inhaled air effectively. These findings highlight the potential of the developed material as a promising solution for applications requiring rapid moisture recovery. [ABSTRACT FROM AUTHOR]

Fog harvesting from the air is one of the sustainable and effective methods to obtain fresh water. Energy-free fog collector systems are widely used for this purpose, but the efficiency of traditional meshes used in these systems is not sufficient. The main objective of this study is to transform ordinary polypropylene fabrics into effective fog harvesting materials by coating them with polymeric thin films using plasma-enhanced chemical vapor deposition (PECVD), which is a one-step and environmentally friendly method. Poly(acrylic acid) (PAA) and poly(2,3,4,4,4-hexafluorobutyl acrylate) (PHFBA) thin films were synthesized using PECVD method as hydrophilic and hydrophobic polymers, respectively. In this study, the effects of surface wettability and fabric weight on fog harvesting efficiency were investigated. Moreover, the effect of surface roughness on fog harvesting efficiency was studied by modifying of the fabrics with silica particles before PECVD coating. The fabrics obtained with hydrophobic thin-film coating on roughened surface showed the highest fog harvesting efficiency (1.14 L/m2.h). The results of this study show that the fabrics modified by the method developed here can be a promising alternative to the meshes currently used in fog collector. [ABSTRACT FROM AUTHOR]

Fouling is a ubiquitous phenomenon occurring in heat transfer devices that inhibits the effective passage of thermal energy, leading to energy and economic losses. In recent years, micro/nanoscale surface modifications have emerged as promising pathways to mitigate the adverse effects of fouling. This review examines micro/nanoscale surface modification methods to mitigate heat exchanger fouling. Various coatings based on titanium, silicon, polymers, amorphous carbon (a-C), electroless nickel-phosphorus (Ni-P), and polyethylene glycol (PEG) are detailed. The coating characteristics in terms of surface chemical and mechanical stability are discussed, and limitations in their commercial utilization are identified. Further, the review outlines the effect of micro/nanoscale surface topographies and novel surface designs on the adhesion and removal of foulants. For instance, laser surface texturing, EDM, anodization, and sandblasting are discussed for generating micro/nanoscale surface topographies. These micro/nanoscale surface topographies play a crucial role in determining surface-foulant interactions and coating durability. It is concluded that the surface energy component is a critical parameter in reducing fouling effects, with low surface energy being favorable for early foulant removal under shear force. Several studies attempting to minimize changes in surface energy components under harsh fouling conditions are discussed in detail.

The control of surface wettability is a technological key aspect and usually poses considerable challenges connected to high cost, nanostructure, and durability, especially when aiming at surface patterning with high and extreme wettability contrast. This work shows a simple and scalable approach by using laser-induced graphene (LIG) and a locally inert atmosphere to continuously tune the wettability of a polyimide/LIG surface from hydrophilic to superhydrophobic (Φ ∼ 160°). This is related to the reduced amount of oxygen on the LIG surface, influenced by the local atmosphere. Furthermore, the influence of the roughness pattern of LIG on the wettability is investigated. Both approaches are combined, and the influence of surface chemistry and roughness is discussed. Measurements of the roll-off angle show that LIG scribed in an inert atmosphere with a low roughness has the highest droplet mobility with a roll-off angle of ΦRO = (1.7 ± 0.3)°. The superhydrophobic properties of the samples were maintained for over a year and showed no degradation after multiple uses. Applications of surfaces with extreme wettability contrast in millifluidics and fog basking are demonstrated. Overall, the proposed processing allows for the continuous tuning and patterning of the surface properties of LIG in a very accessible fashion useful for "lab-on-chip" applications. [ABSTRACT FROM AUTHOR]

With the rapid progress in data mining, deep learning, and artificial intelligence, the demand for datacenters of various sizes increases globally. Datacenters typically require an environment with properly controlled temperature and humidity conditions for their proper operations. These needed environmental conditions are always provided by an air conditioning system. In humid and hot regions, both energy consumption and the splash of water condensate in using the fin-and-tube heat exchangers are of concern because reliability issues can occur. In this study, the effects of fin surface hydrophilic/hydrophobic coatings on the performance of the fin-and-tube heat exchangers, including the heat transfer rate, pressure drop, and water-condensate splash, were investigated experimentally. By varying the cooling air speeds and fin pitches, the results show that hydrophilic surface coating is an effective method in reducing both the pressure drop (thus saving energy) and the condensate splash, while not affecting the heat transfer rates significantly. The water splash reduction is achieved by both the increased air speed for splashing and a smaller amount of splashing. Water splash can even be completely eliminated if the airspeed was below about 3 m/s. In contrast, hydrophobic surface coating will increase both pressure drop and water splash; thus, should be applied with caution. [ABSTRACT FROM AUTHOR]

Copyright of Materials & Technologies / Materiali in Tehnologije is the property of Institute of Metals & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The hydrophobic/hydrophilic character of some conductive polymer (CP) coatings can be switched in the function of the working conditions of these adaptive materials. We studied the influence of electrical stimuli and intrinsic physical characteristics (nature of the polymerizable core, dopants, the droplet dimension and physical properties, surface roughness, etc.) on the CP wettability. A simulation strategy was developed for determining the contact angle (CA) of a liquid droplet on a CP layer with roughness. The method was tested for new reported CP composites, but with new dopants. The results indicate that the influences on the material wettability are correlated, and in practice, modification of more than one parameter converges to a wanted behavior of the material. E.g., the CP porous film of poly(3-hexylthiophene) (P3HT) + [6,6]-phenyl-C61-butyricacid-methyl-ester (PCBM) changes its wettability at voltages of up to 26 V, but if doping ions are inserted and the roughness geometry is modified, the voltage decreases twice. Our multi-parametrical study points out that the polymer wettability type is driven by the voltage, but this effect is tuned differently by each internal parameter. The thin films' effect and the dopants (in-situ and ex-situ) significantly decrease the actuation voltage. We also illustrated that the wettability type does not change for specific sets of parameters. [ABSTRACT FROM AUTHOR]

The aim of this contemporary work was to formulate a controlled release mucoadhesive nanoparticle formulation for enhancing the oral bioavailability of Ticagrelor (TG), a BCS class IV drug, having low oral bioavailability of about 36%. The nanoparticles can act as efficient carriers for hydrophobic drugs, due to having high surface area and hence can improve their aqueous solubility due to their hydrophilic nature. The nanoparticles (NPs) of TG were formulated using chitosan (CH) as polymer and sodium tripolyphosphate (TPP) as cross-linker, by ionic gelation technique with varying concentrations of polymer with respect to TG and TPP. Characterization of prepared nanoparticles was carried out to assess zeta potential, size, shape, entrapment efficiency (EE) and loading capacity (LC), using zeta sizer, surface morphology and chemical compatibility analysis. Drug release was observed using UV-Spectrophotometer. By increasing concentration of CH the desired size of particles (106.9 nm), zeta potential (22.6 mv) and poly dispersity index (0.364) was achieved. In vitro profiles showed a controlled and prolonged release of TG in both lower pH-1.2 and neutral pH-7.4 mediums, with effective protection of entrapped TG in simulated gastric conditions. X-ray diffraction patterns (XRD) showed the crystalline nature of formed NPs. Hence, this effort showed that hydrophobic drugs can be effectively encapsulated in nanoparticulate systems to enhance their solubility and stability, ultimately improving their bioavailability and effectiveness with better patient compliance by reducing dosing frequencies as well.

Existing soft ionic conductors fall into two distinct categories: liquid‐rich ionic conductors containing large amounts of liquid electrolytes (≈70–90 wt.% water for hydrogels and ≈20–80 wt.% ionic liquids for ionogels), and liquid‐free ionic conductors that do not contain liquid components (e.g., ionic conductive elastomers). However, they are often plagued by dehydration, leakage of toxic ionic liquids, and air aging. Here, using hydrophobic polymer networks and hydrophilic salt hydrates, ionic conductive elastomers (s‐ICEs for short) containing only a tiny amount of bound water (≈1–5 wt.% are synthesized). Thanks to the small embedded water content, the s‐ICEs are advantageous over liquid‐rich ionic conductors in terms of enhanced mechanical/electrical stabilities and safety; they also outperform previously reported liquid‐free ionic conductors by avoiding air‐aging issues. The s‐ICEs introduced here also show excellent stretchability, good elasticity, high fracture resistance, desirable optical transparency and ionic conductivity, which are comparable to those of state‐of‐the‐art liquid‐rich and liquid‐free ionic conductors. With all the above advantages, the s‐ICE represents an ideal material for practical applications of soft ionotronics in ambient conditions. [ABSTRACT FROM AUTHOR]

Materials based on photocurable resins and pharmaceutically active agents (APIs) are gaining interest as a composite drug delivery system. In this study, a composite of caffeine with acrylic resin was obtained using an additive manufacturing method of digital light processing (DLP) as a potential material for transdermal drug delivery. The mechanical properties of the composites and the ability to release caffeine from the resin volume in an aqueous environment were investigated. The amount of caffeine in the resulting samples before and after release was evaluated using a gravimetric method. The global thresholding method was also evaluated for its applicability in examining caffeine release from the composite. It was shown that as the caffeine content increased, the strength properties worsened and the ability to release the drug from the composite increased, which was caused by negligible interfacial interactions between the hydrophilic filler and the hydrophobic matrix. The global thresholding method resulted in similar caffeine release rate values compared to the gravimetric method but only for samples in which the caffeine was mainly located near the sample surface. The distribution of caffeine throughout the sample volume made it impossible to assess the caffeine content of the sample using global thresholding. [ABSTRACT FROM AUTHOR]

Peatlands play a critical role in the global carbon cycle, storing large amounts of carbon because of a net imbalance between primary production and the microbial decomposition of the organic matter. Nevertheless, peatlands have historically been drained for energy sources (e.g. peat briquettes), forestry, or agriculture - practices that could affect the quality of the soil organic matter (SOM) composition, hydrophobicity and humification index. This study compared the effect of land use change on the quality and composition of peatland organic material in Co-Offaly, Ireland. Specifically, drained and grazing peat (grassland), drained and forest plantation peat (forest plantation), drained and industrial cutaway peat (cutaway bog) and an undrained actively accumulating bog (as a reference for natural peatland) were studied. Fourier-transform infrared spectroscopy (FTIR) was used to examine the organic matter quality, specifically the degree of decomposition (DDI), carbon chemistry signatures, hydrophobicity and humification index. The ratio of hydrophobic to hydrophilic group intensities was calculated as the SOM hydrophobicity. In general, there is greater variance in the carbon chemistry signature, such as aliphatic methyl and methylene, C=O stretching of amide groups, aromatic C=C, strong H-bond C=O of conjugated ketones and O–H deformation and C– O stretching of phenolics and secondary alcohols of the peat samples from industrial cutaway bog samples than in the grassland and forest plantation samples. The hydrophobicity and the aromaticity of the soil organic matter (SOM) are significantly impacted by land use changes, with a trend of order active bog > forest plantation > industrial cutaway bog > grassland. A comparison of the degree of decomposition index of the peat from active bog showed a more advanced state of peat degradation in grassland and industrial cutaway bog and, to a lesser extent, in forest plantation.

Shrink film is a thin sheet of polystyrene plastic that shrinks to 25–40% of its original size when heated. This study investigated the shrinkage factor of the film at different temperatures and baking times to determine the optimal fabrication recipe for shrink film microfluidic device production. Additionally, this study characterized the properties of shrink film, including minimum possible feature size and cross-section geometries, using manual engraving and the CAMEO 4 automated cutting machine. The optimal shrinkage factor ranged from 1.7 to 2.9 at 150 °C and a baking time of 4 min, producing the ideal size for microfluidic device fabrication. The X- and Y-axes shrank ~2.5 times, while Z-axis thickened by a factor of ~5.8 times. This study achieved a minimum feature size of 200 microns, limited by the collapsing of channel sidewalls when shrunk, leading to blockages in the microchannel. These findings demonstrate the feasibility and versatility of using shrink film as a cost-effective and efficient material for the rapid fabrication of microfluidic devices. The potential applications of this material in various fields such as the medical and biomedical industries, bacteria and algae culture and enumeration are noteworthy.

Many studies have focused on surface texturing to control friction and wear in the past few decades. The underlying reasons for surface texturing effects under various contact situations remain a source of debate. The connection between surface roughness and friction between two sliding surfaces is more complicated than it looks at first glance. In this paper, samples of a highly resistive p-type silicon were anodized to get various pore sizes ranging from 0.01 up to 3.2 microns using two electrolyte solutions and varying the electric current. The wetting properties were determined via contact angle analysis, while pore size and shape measurements were performed by scanning electron microscopy. The tribological tests were performed on a tribometer (UMT, Bruker) in a reciprocating mode for 15 min with a 3N load, 5 Hz, and a 10 mm diameter steel ball. Wear surfaces were analyzed by optical microscopy and non-contact 3D profilometry. The results showed that low electric currents generate mesoporous silicon surfaces with low friction. Higher currents generate macroporous silicon surfaces, modifying the surface roughness and wetting properties from hydrophilic to hydrophobic and increasing friction. The pore size is directly related to the wear volume and scar diameter measured from optical micrographs and profilometry 3D. The larger the pore size and nanostructured peaks, the greater the contact angle, friction, and wear.

Abstract Existing soft ionic conductors fall into two distinct categories: liquid‐rich ionic conductors containing large amounts of liquid electrolytes (≈70–90 wt.% water for hydrogels and ≈20–80 wt.% ionic liquids for ionogels), and liquid‐free ionic conductors that do not contain liquid components (e.g., ionic conductive elastomers). However, they are often plagued by dehydration, leakage of toxic ionic liquids, and air aging. Here, using hydrophobic polymer networks and hydrophilic salt hydrates, ionic conductive elastomers (s‐ICEs for short) containing only a tiny amount of bound water (≈1–5 wt.% are synthesized). Thanks to the small embedded water content, the s‐ICEs are advantageous over liquid‐rich ionic conductors in terms of enhanced mechanical/electrical stabilities and safety; they also outperform previously reported liquid‐free ionic conductors by avoiding air‐aging issues. The s‐ICEs introduced here also show excellent stretchability, good elasticity, high fracture resistance, desirable optical transparency and ionic conductivity, which are comparable to those of state‐of‐the‐art liquid‐rich and liquid‐free ionic conductors. With all the above advantages, the s‐ICE represents an ideal material for practical applications of soft ionotronics in ambient conditions.

Improving condensation on large-scale surfaces promotes a wide range of manufacturing fields. To take advantage of both dropwise and filmwise condensation properties, both hydrophobic and hydrophilic surfaces can be developed on one hybrid surface. In this paper, experimental studies were performed on vapor condensation over a flat vertical plate. Three different surfaces were utilized: hydrophilic (aluminum), hydrophobic (coated), and hybrid surfaces with distinctive hydrophilic and hydrophobic patterns. The effect of the volume flow rate of the cooling water was investigated from 5 L/min to 15 L/min. For the hybrid surfaces, three types of patterns were studied: separated holes of hydrophilic patterns (the island) with two different diameters, arrow pattern, and tree pattern. According to the results, the heat transfer rate varied as the surface conditions changed. For the aluminum surface that resulted in filmwise condensation mode, the observed heat transfer rate was less than that of the coated surface, which showed a combination of filmwise and dropwise condensation modes. For the hybrid surfaces, the observed heat transfer rate was higher than that of the coated surface. From all the surfaces in this study, the highest heat transfer rate was for the 2.0 mm diameter island pattern.

Superhydrophobic surfaces have many interesting applications because of their self‐cleaning, waterproof, anti‐biofouling, anti‐corrosion, and low‐adhesion properties. Accordingly, numerous surfaces with hierarchical micro/nanostructures are designed and engineered to achieve superhydrophobicity. However, these surfaces have two major problems. First, they lose superhydrophobic properties over time, primarily because of environmental conditions such as vibration, external pressure, evaporation, and pollution. Second, most superhydrophobic surfaces fail to repel all types of liquids, especially those with low surface tensions. To address this bottleneck, microstructures with re‐entrant curvature have emerged, demonstrating excellent liquid‐repellent abilities and robustness. Additionally, microstructures with re‐entrant curvature have significant applications in designing surfaces with unidirectional wetting properties for passive liquid handling. Accordingly, this review systematically summarizes the design and fabrication strategies of these re‐entrant microstructures. The emphasis is given to wettability studies and other surface properties of re‐entrant microstructures and their applications, especially for liquid self‐transporting. This paper also highlights the potential applications and remaining technical challenges of fabricating these structures. Finally, the study is concluded by providing the future directions in this promising field. [ABSTRACT FROM AUTHOR]

This study elucidates the effect of thin porous hydrophobic covering layers on the in‐plane wicking properties of a hydrophilic fibrous membrane. Polyacrylonitrile (PAN) fibrous membrane is used as the hydrophilic membrane model and poly(vinylidene fluoride‐hexafluoropropylene) (PVDF‐HFP) fibrous membranes as hydrophobic covers, both prepared by electrospinning. The vertical wicking height is measured to express the in‐plane wicking properties. The results show that the PVDF‐HFP fibrous layer profoundly impacted the in‐plane wicking properties. When the PVDF‐HFP layer is 5.00–7.05 µm in thickness, the PVDF‐HFP/PAN composite membranes show a directional water transport property. The wicking height is higher than the other composite membranes with either a thinner PVDF‐HFP layer (<5.00 µm), which causes a two‐way liquid transport, or a thicker PVDF‐HFP layer (>7.05 µm), which stops water permeation from both sides. Such a trend happened no matter whether the PVDF‐HFP layer covered one or both PAN membrane sides. The composite membranes with a PVDF‐HFP layer thicker than 7.05 µm show the smallest wicking height. By changing PVDF‐HFP layer thickness, the wicking height can be adjusted by 50–110%. Such thickness‐dependent wicking capability is novel, having not been reported in the previous literature. It comes from the combined action of hydrophobic and hydrophilic surfaces on water. The tunable wicking properties combined with the water‐absorbing and transport properties enabled the PVDF‐HFP/PAN fibrous membranes to exhibit different functions. They offer opportunities to develop novel "smart" membranes for various applications. [ABSTRACT FROM AUTHOR]

In this work, molecular dynamics simulation is used to describe and analyze the behavior of model collagen polymer (Pro-Pro-Gly)9. This project aims to highlight the important role of molecular dynamic simulation in determining the structural stability of collagen, and establishing collagen as a hydrophobic or hydrophilic protein under different temperatures. The system was simulated at four different temperatures (300, 310, 320, and 330 K). The results indicate that the average number of hydrogen bonds within the protein and the protein backbone was similar at each temperature. The solvent-accessible surface area of hydrophobic and hydrophilic atoms for the four temperatures indicates that the collagen model peptide is mostly hydrophobic. All the results show that the structure of the studied polymer was the least stable at 320 K and the most stable at lower temperatures (300 K). The average effect across the first 100 ns was investigated. The dominant states obtained within this time interval will be explored in following studies. Researchers can use the results of this work to develop collagen with the appropriate thermal stability for biological applications. [ABSTRACT FROM AUTHOR]

The environmental friendly flexible solid state linear supercapacitor (FSLSc) based on the hierarchical hybrid yarn with core-shell type structure of poly(3,4-ethylenedioxythiophene): polystyrenesulfonate (PEDOT:PSS) and hydrophilic carbon nanotubes (CNTs) sheet, fabricated using novel biscrolling technique is proposed. The hierarchical hybrid yarn structure of the electrode establishes the improved electrochemical interface of PEDOT:PSS with the both the hydrophilic CNTs and an aqueous PVA/H 3 PO 4 gel electrolyte. The exterior surface of the yarn electrode rich in PEDOT:PSS which interact with ions from electrolyte and stores charges faradaically while the core region with dense CNTs yarn contributes with its multifunctional capabilities such as EDLC type capacitor, current collector and mechanical support. The observed two-fold decrease in ESR value (∼49Ω) and two-fold increase in capacitance (∼112.76 F/g) for hybrid yarn electrode with N-methyl-2-pyrrolidone (NMP) treated hydrophilic CNTs compared to the one with pristine CNTs, confirms the improved interface of PEDOT:PSS formed with hydrophilic CNTs and aqueous electrolyte. The FSLSc devices with NMP treated CNTs hybrid yarn electrodes exhibited excellent electrochemical performance in terms of the maximum power and energy density of 980 W/kg and 3.799 Wh/kg, respectively. The FSLSc displayed remarkable cycling performance upto 5000 cycles of charge-discharge and a robust bending stability after 1000 bending cycles, making it promising for practical application of the next-generation flexible solid state electrochemical energy storage in e-textiles. [Display omitted] [ABSTRACT FROM AUTHOR]