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Discusses the properties of matter pertaining to whether an object is smooth or rough, defining both words and using examples to illustrate the differences.

The surface that hates almost everything Inspired by the insect-eating Nepenthes pitcher plant, which snares its prey on a surface lubricated by a remarkably slippery aqueous secretion, Joanna Aizenberg and colleagues have synthesized omniphobic surfaces that can self-repair and function at high pressures. Their 'slippery liquid-infused porous surfaces' (or SLIPS) exhibit almost perfect slipperiness towards polar, organic and complex liquids. SLIPS function under extreme conditions, are easily constructed from inexpensive materials and can be endowed with other useful characteristics, such as enhanced optical transparency, through the selection of appropriate substrates and lubricants. Ultra-slippery surfaces of this type might find application in biomedical fluid handling, fuel transport, antifouling, anti-icing, optical imaging and elsewhere. Creating a robust synthetic surface that repels various liquids would have broad technological implications for areas ranging from biomedical devices and fuel transport to architecture but has proved extremely challenging 1 . Inspirations from natural nonwetting structures 2 , 3 , 4 , 5 , 6 , particularly the leaves of the lotus, have led to the development of liquid-repellent microtextured surfaces that rely on the formation of a stable air–liquid interface 7 , 8 , 9 . Despite over a decade of intense research, these surfaces are, however, still plagued with problems that restrict their practical applications: limited oleophobicity with high contact angle hysteresis 9 , failure under pressure 10 , 11 , 12 and upon physical damage 1 , 7 , 11 , inability to self-heal and high production cost 1 , 11 . To address these challenges, here we report a strategy to create self-healing, slippery liquid-infused porous surface(s) (SLIPS) with exceptional liquid- and ice-repellency, pressure stability and enhanced optical transparency. Our approach—inspired by Nepenthes pitcher plants 13 —is conceptually different from the lotus effect, because we use nano/microstructured substrates to lock in place the infused lubricating fluid. We define the requirements for which the lubricant forms a stable, defect-free and inert ‘slippery’ interface. This surface outperforms its natural counterparts 2 , 3 , 4 , 5 , 6 and state-of-the-art synthetic liquid-repellent surfaces 8 , 9 , 14 , 15 , 16 in its capability to repel various simple and complex liquids (water, hydrocarbons, crude oil and blood), maintain low contact angle hysteresis (<2.5°), quickly restore liquid-repellency after physical damage (within 0.1–1 s), resist ice adhesion, and function at high pressures (up to about 680 atm). We show that these properties are insensitive to the precise geometry of the underlying substrate, making our approach applicable to various inexpensive, low-surface-energy structured materials (such as porous Teflon membrane). We envision that these slippery surfaces will be useful in fluid handling and transportation, optical sensing, medicine, and as self-cleaning and anti-fouling materials operating in extreme environments.

A comprehensive comparison of the trends and drivers of global surface and canopy urban heat islands (termed Is and Ic trends, respectively) is critical for better designing urban heat mitigation strategies. However, such a global comparison remains largely absent. Using spatially continuous land surface temperatures and surface air temperatures (2003–2020), here we find that the magnitude of the global mean Is trend (0.19 ± 0.006°C/decade, mean ± SE) for 5,643 cities worldwide is nearly six‐times the corresponding Ic trend (0.03 ± 0.002°C/decade) during the day, while the former (0.06 ± 0.004°C/decade) is double the latter (0.03 ± 0.002°C/decade) at night. Variable importance scores indicate that global daytime Is trend is slightly more controlled by surface property, while background climate plays a more dominant role in regulating global daytime Ic trend. At night, both global Is and Ic trends are mainly controlled by background climate. Plain Language Summary Surface and canopy urban heat islands (surface and canopy UHIs, termed Is and Ic) are two major UHI types. These two counterparts are both related to urban population heat exposure and have long been a focus of urban climate research. However, the differences in the trends and major determinants of Is and Ic over global cities remain largely unclear. Based on spatially continuous land surface temperature and surface air temperature observations from 2003 to 2020, we find that the global mean Is trends are about 6.3 times and 2 times the Ic trends during the day and at night, respectively. During the day, the global Is trend is more regulated by surface property than by background climate, and vice versa for global Ic trend. At night, both the global Is and Ic trends are mainly regulated by background climate. These findings are important for better understanding global urban climate change and informing heat mitigation strategies. Key Points The global Is trend is six‐fold and twofold larger than the Ic trend during the day and at night, respectively During the day, global Is trend is slightly more controlled by surface property, yet background climate plays a dominant role in Ic trend At night, both global Is and Ic trends are more regulated by background climate

It is not clear whether different radiation methods have different effects on enamel. The purpose of this study was to compare the effects of single and fractionated radiation on enamel and caries susceptibility and to provide an experimental basis for further study of radiation‑related caries. Thirty-six caries-free human third molars were collected and randomly divided into three groups (n = 12). Group1 (control group) was not exposed to radiation. Group 2 received single radiation with a cumulative dose of 70 Gy. Group 3 underwent fractionated radiation, receiving 2 Gy/day for 5 days followed by a 2-day rest period, for a total of 7 weeks with a cumulative dose of 70 Gy. Changes in microhardness, roughness, surface morphology, bacterial adhesion and ability of acid resistance of each group were tested. Scanning electron microscope revealed that the enamel surface in both radiation groups exhibited unevenness and cracks. Compared with the control group, microhardness and acid resistance of enamel decreased, while roughness and bacterial adhesion increased in both the single radiation and fractionated radiation groups. Compared with the single radiation group, the enamel surface microhardness and acid resistance decreased in the fractionated radiation group, while roughness and bacterial adhesion increased. Both single radiation and fractionated radiation resulting in changes in the physical and biological properties of enamel, with these changes being more pronounced in the fractionated radiation group. Therefore, fractionated radiation is recommended as a more suitable method for constructing a radiation‑related caries model in vitro.

The human finger is exquisitely sensitive in perceiving different materials, but the question remains as to what length scales are capable of being distinguished in active touch. We combine material science with psychophysics to manufacture and haptically explore a series of topographically patterned surfaces of controlled wavelength, but identical chemistry. Strain-induced surface wrinkling and subsequent templating produced 16 surfaces with wrinkle wavelengths ranging from 300 nm to 90 μm and amplitudes between 7 nm and 4.5 μm. Perceived similarities of these surfaces (and two blanks) were pairwise scaled by participants and interdistances among all stimuli were determined by individual differences scaling (INDSCAL). The tactile space thus generated and its two perceptual dimensions were directly linked to surface physical properties – the finger friction coefficient and the wrinkle wavelength. Finally, the lowest amplitude of the wrinkles so distinguished was approximately 10 nm, demonstrating that human tactile discrimination extends to the nanoscale.

Plasmons are directly launched in graphene, and their key parameters — propagation and attenuation — are studied with near-field infrared nano-imaging. Voltage-controlled graphene plasmonics Plasmonic devices, which exploit surface plasmons (electromagnetic waves that propagate along the surface of metals) offer the possibility of controlling and guiding light at subwavelength scales. All eyes are on graphene — atom-thick layers of carbon — as a promising platform for plasmonic applications because it can strongly interact with light and host surface plasmons in the infrared range. Two independent groups reporting in this issue of Nature show that plasmons can be directly launched in graphene, and observed with near-field optical microscopy. Moreover, the wavelengths and amplitudes of the plasmons can be tuned by a gate voltage, a promising capability for the development of on-chip graphene photonics for use in applications including telecommunications and information processing. Surface plasmons are collective oscillations of electrons in metals or semiconductors that enable confinement and control of electromagnetic energy at subwavelength scales 1 , 2 , 3 , 4 , 5 . Rapid progress in plasmonics has largely relied on advances in device nano-fabrication 5 , 6 , 7 , whereas less attention has been paid to the tunable properties of plasmonic media. One such medium—graphene—is amenable to convenient tuning of its electronic and optical properties by varying the applied voltage 8 , 9 , 10 , 11 . Here, using infrared nano-imaging, we show that common graphene/SiO 2 /Si back-gated structures support propagating surface plasmons. The wavelength of graphene plasmons is of the order of 200 nanometres at technologically relevant infrared frequencies, and they can propagate several times this distance. We have succeeded in altering both the amplitude and the wavelength of these plasmons by varying the gate voltage. Using plasmon interferometry, we investigated losses in graphene by exploring real-space profiles of plasmon standing waves formed between the tip of our nano-probe and the edges of the samples. Plasmon dissipation quantified through this analysis is linked to the exotic electrodynamics of graphene 10 . Standard plasmonic figures of merit of our tunable graphene devices surpass those of common metal-based structures.

The surface properties and electrical behavior of carbon-based materials can be effectively modified by energetic ion irradiation. In the present study, graphene oxide (GO) and cyclic olefin copolymer foils (COC, Topas 112 and 011, respectively) were irradiated with 1 MeV Au ions using a 3 MV Tandetron accelerator at fluences of 1 × 1014, 1 × 1015, and 2.5 × 1015 cm−2. The irradiation induced systematic modifications in surface chemistry, morphology, wettability, and electrical properties. Composition changes were investigated using Rutherford backscattering spectrometry (RBS) and elastic recoil detection analysis (ERDA), while surface morphology and roughness were characterized by atomic force microscopy (AFM). This revealed a clear fluence-dependent evolution of nanoscale topography. The vibrational characteristics were assessed through Raman spectroscopy, and the chemical composition of the surface layers was analyzed by X-ray photoelectron spectroscopy (XPS). The surface wettability was evaluated by static contact angle measurements, and surface free energy was determined using the Owens–Wendt–Rabel–Kaelble (OWRK) method. These measurements showed a consistent decrease in water contact angle and an increase in surface free energy with increasing ion fluence in the COC substrates, whereas GO exhibited a distinct response. Electrical characterization demonstrated a pronounced fluence-dependent decrease in sheet resistivity in polymers. The results show that 1 MeV Au ion irradiation enables systematic and fluence-dependent modification of both surface and electrical properties.

Additive manufacturing using metal powders is becoming increasingly popular due to its versatility in creating structural components of various shapes. Among the various additive manufacturing methods (or 3D printing), direct metal laser sintering (DMLS) is one of the most frequently used technologies. The material most frequently used in DMLS technology is the titanium (Ti6Al4V) alloy, widely preferred in defense, aerospace, automotive, energy, and biomedical industries. This research study examines the mechanical and surface porosity and roughness properties of the 3D-printed Ti6Al4V (Grade 23) alloy specimens. In addition to additive manufacturing, a post-processing treatment known as stress-relieving (SR) heat treatment is also utilized for additively manufactured specimens. Four differently shaped walls (diamond, square, circle, and hexagon) were additively manufactured. The mechanical properties of the 3D-printed Ti6Al4V alloy specimens were tested using compression testing and hardness tests using Rockwell and Vickers scales. These tests were conducted before and after post-process SR heat treatment. Additionally, surface roughness analysis was conducted on the specimens to determine any changes in the material’s surface properties after the SR heat treatment. It was observed that the heat-treated (HT) specimens existed to have more cracks and oxidation compared to the non-heat-treated (NHT) ones. According to the surface roughness results, the circular-shaped heat-treated wall (CSHTW) specimen has the lowest average roughness (Ra) value of 210.31 µin (5.34 µm), and the corresponding maximum height (Rz) was 897.99 µin (22.81 µm). Also, the average Rockwell hardness value of the HT specimens was reported to present an increase of approximately 3% compared to the NHT specimens. The diamond-shaped heat-treated wall (DSHTW) specimen exhibited the highest Vickers hardness value of 605.08 (± 233.98) HV. It was found that the CSHTW specimens had the highest elastic modulus and yield strengths among all the geometries, with a value 38 GPa and 1380 MPa, respectively, indicating that they could resist deformation better than the other specimens. Overall, this study is important because additively manufactured Ti6Al4V alloy components are increasingly used in many industries, as it offers significant reductions in costs, material waste, manufacturing lead times, and improved performance outcomes.

The increase in environmental consciousness and waste-to-wealth concepts in the automobile sector has led to the use of natural fibers in desirable quantities. The current study deals with the extraction, treatment, and utilization of Lycium ferocissimum stem fibers for friction composite in braking applications. The fibers of Lycium ferocissimum were extracted through manual retting and subsequently treated with benzoyl chloride. Both the benzoyl chloride treated and treated of Lycium ferocissimum were employed as reinforcements in the fonnulation of a friction composite, following the standard practices of the industry, and the comparison was made using commercially available friction composite. The developed friction composites were tested for original equipment manufacturer quality requirements following industrial Standards. The friction composite's tribological behavior was analyzed using the Chase test following the Society of Automotive Engineers standards. The worn surface characteristics were analyzed using scanning electron microscope. The test results elucidated that benzoyl chloride-treated Lycium ferocissimum fibers-based friction composites showed good frictional properties with better wear resistance compared to others, having a weight loss of 5.4%.

Synthesis for new pyrazolin derivatives, which oriented for coordination with Cr(III) ion then all new synthesizes were characterized with reliable techniques. Octahedral geometry was the only form suggested from bi-negative tetra-dentate mode of bonding within bi-nuclear complexes. Such offering is based on analytical and spectral tools (IR, UV–Vis and MS). TGA confirms and discriminates water molecules profiles with relative to coordination sphere. Practical and computational XRD patterns appeared having high extent of similarity attributing to nano-crystalline particulate sizes. Hirshfeld surface properties and the efficiency of molecular-contact in crystal-packing, were obtained upon Crystal explorer 3.1 software beside VESTA package. Some physical indices were estimated based on frontier energy gaps over optimized structures upon Gauss-view software. Computational simulation approach was implemented to monitor changes on cancer cell proteins after treatment by new Cr(III) complexes, for assessment. Promising antitumor activity might be expected for Cr(III)-L 4 , Cr(III)-L 3 and Cr(III)-L 2 complexes, based on exported interaction parameters. It is worthy to note that, in-vitro assay reflects an excellent cytotoxicity recorded for such three complexes, in excellent harmony with simulation suggestions.