Superoleophobicity is a phenomenon where the contact angles of various oil droplets with low surface tension on a solid surface are larger than 150°. In the past few years, there has been much growing interest in the design and application of superoleophobic surfaces. Such surfaces have great significance for both fundamental research and a variety of practical applications, including oil-repellent coatings, self-cleaning, oil/water separation, oil droplet manipulation, chemical shielding, anti-blocking, designing liquid microlens, oil capture, bioadhesion, guiding oil movement and floating on oil. Herein, we systematically summarize the recent developments of superoleophobic surfaces. This review focuses on the design, fabrication, characteristics, functions, and important applications of various superoleophobic surfaces. Although many significant advances have been achieved, superoleophobic surfaces are still in their "toddler stage" of development. The current challenges and future prospects of this fast-growing field of superoleophobicity are discussed.

No abstract

Radiofrequency (RF) field wave behavior and associated nonuniform image intensity at high magnetic field strengths are examined experimentally and numerically. The RF field produced by a 10-cm-diameter surface coil at 300 MHz is evaluated in a 16-cm-diameter spherical phantom with variable salinity, and in the human head. Temporal progression of the RF field indicates that the standing wave and associated dielectric resonance occurring in a pure water phantom near 300 MHz is greatly dampened in the human head due to the strong decay of the electromagnetic wave. The characteristic image intensity distribution in the human head is the result of spatial phase distribution and amplitude modulation by the interference of the RF traveling waves determined by a given sample-coil configuration. Enhancements in signal-to-noise ratio (SNR) and T* 2 contrast arising from high static magnetic field strengths are desirable for in vivo MR applications. Thus, the number of high-field human MRI systems has increased rapidly in recent years (1-10). The advent of high-field human imaging systems introduces new challenges in radiofrequency (RF) engineering (11,12). Because at high frequencies the wavelength of the RF field is comparable to or less than that of the dimension of the human body, the RF magnetic field (B 1 ) inside a sample exhibits prominent wave behavior (13-16). Additionally, the homogeneity of the B 1 field and source currents in the RF coil are strongly perturbed by sample loading (17-19). The B 1 field distribution inside a sample is important for both specific absorption rate (SAR) assessment and RF coil engineering at high frequency. However, mathematical treatment of the RF field in such systems can be extremely complicated because 1) the quasi-static approximations are no longer valid, and Maxwell's wave equation must be employed; and 2) the geometry of the human body is irregular, and electromagnetic properties of tissues are heterogeneous. Thus, computer numerical calculation becomes an effective and indispensable tool for studying interactions of the RF field with the human body at high field (20 -24). Associated with the RF field wave behavior, the distributions of the B 1 field and its circularly polarized components B ϩ and B -, which are directly responsible for the MR image intensity distribution, become distinctively different from one another. Consequently, the relationship of RF field polarization to coil configuration and sample electric properties needs to be analyzed in order to understand the resultant image intensity distribution. Computer modeling provides an effective way to study this problem, and may provide insight into complex RF field wave behavior and its dependence on the electrical properties of the sample. In this report, we present a study specifically devised to analyze high-frequency wave behavior of the RF field with the aid of numerical calculation and parallel experimental measurements. METHODSThe study was carried out using water and saline phantoms with a 10-cm-diameter sur...

Purpose: To aid in discussion about the mechanism for central brightening in high field magnetic resonance imaging (MRI), especially regarding the appropriateness of using the term dielectric resonance to describe the central brightening seen in images of the human head. Materials and Methods:We present both numerical calculations and experimental images at 3 T of a 35-cm-diameter spherical phantom of varying salinity both with one surface coil and with two surface coils on opposite sides, and further numerical calculations at frequencies corresponding to dielectric resonances for the sphere. STRONG CENTRAL BRIGHTENING has been observed in magnetic resonance imaging (MRI) of the human head using volume coils at high B 0 field strength and high B 1 field frequency (1-3). Recently there has been some discussion in the literature about the appropriateness of attributing this brightening to dielectric resonance (4 -8), as it has been previously (1,2). While it is certain that B 1 wavelengths are on the order of dimensions of the human body at these frequencies, relatively high tissue conductivity inhibits the creation of strong resonances (4 -8), and alternative explanations for the observed central brightening are warranted. ResultsA true dielectric resonance is characterized by relatively large oscillating electromagnetic fields in and around an object with a frequency of oscillation near a natural frequency for the object, and elicited by a relatively small stimulus near that natural frequency. The natural resonant frequencies for an object are determined by the geometry and electrical properties of the object, as well as the electrical properties of the surrounding medium. A single object typically has several different resonant modes at several different frequencies, each with a characteristic electromagnetic field pattern (8 -11). For some simple shapes, these frequencies and the characteristic field patterns can be calculated with analytical methods (11). But classically, the term resonance refers to field intensity as a function of frequency more than as a function of position.Although other authors have pointed out the lack of strong true resonances in biological tissues, they have not offered an easily understandable alternative explanation for observed central brightening. An enhancement of magnetic field strength near the center of an object can be created by a number of ways, and is not by itself evidence of a dielectric resonance. For example, midway between sources of traveling waves with currents in opposing directions (or 180°out of phase) is a location of constructive magnetic field interference at any frequency, provided the waves from each source travel through the same media for the same distance. This can occur even in an empty coil if the frequency is high enough for the wavelength to be on the order of the coil dimensions. We suggest that it is the combination of multiple current-carrying elements in the coil and wavelength effects in the sample leading to constructive and destructive interfe...

We compared reflex responses to static handgrip at 30% maximal voluntary contraction (MVC) in 26 untrained men (mean age 35 +/- 3 yr) and 23 untrained women (mean age 39 +/- 4 yr). Women demonstrated attenuated increases in blood pressure and muscle sympathetic nerve activity (MSNA; by microneurography) compared with men. This difference was also observed during a period of posthandgrip circulatory arrest. 31P-nuclear magnetic resonance (NMR) spectroscopy studies demonstrated attenuations in the production of diprotonated phosphate and the development of cellular acidosis in women compared with men. Subjects also performed ischemic handgrip to fatigue. During this paradigm, MSNA responses were similar in the two groups, suggesting that freely perfused conditions are necessary for the full expression of the gender effect. Finally, we examined MSNA responses to adductor pollicus exercise in 7 men (26 +/- 1 yr) and 6 women (25 +/- 2 yr). MVC values and times to fatigue were similar in the two groups (MVC: men, 4.3 +/- 0.4 kg; women, 4.0 +/- 0.3 kg; not significant. Time to fatigue: men, 209 +/- 16 s; women, 287 +/- 50 s; not significant). At periods of end exercise and postexercise circulatory arrest, MSNA responses were attenuated in the women compared with the men. We conclude that, during nonischemic static exercise, sympathetic neural outflow is less in women compared with men. This response is due to an attenuated metaboreflex in women. Finally, on the basis of the adductor pollicus experiments, this effect appears independent of muscle mass, workload, and the level of training.

Background-Recent magnetic resonance imaging (MRI) studies suggest increased transverse relaxation rate (R2*) and reduced diffusion tensor imaging (DTI) fractional anisotropy (FA) values in the SN in PD. The R2* and FA changes may reflect different aspects of PD-related

Although sensory neuropathy is often emphasized in considerations of diabetic foot pathology, our results show that the consequences of motor neuropathy in the feet are profound in people with diabetes. This has implications for foot function and may play a significant role in postural instability. However, intrinsic muscle atrophy does not necessarily appear to imply toe deformity.

A micro-/nanoscale hierarchical rough structure inspired by the underwater superaerophobicity of fish scales was fabricated by ablation of a silicon surface by a femtosecond laser. The resultant silicon surface showed superhydrophilicity in air and became superaerophobic after immersion in water. Additionally, inspired by the underwater superaerophilicity of lotus leaves, we showed that the polydimethylsiloxane surface after femtosecond laser ablation exhibits superhydrophobicity in air and becomes superaerophilic in water. The underwater superaerophobic surface showed excellent antibubble ability, whereas the underwater superaerophilic surface could absorb and capture air bubbles in a water medium. The experimental results revealed that the in-air superhydrophilic surface generally shows superaerophobicity in water and that the in-air superhydrophobic surface generally shows underwater superaerophilicity. An underwater superaerophobic porous aluminum sheet with through microholes was prepared, and this sheet was able to intercept underwater bubbles and further remove bubbles from water. In contrast, the underwater superaerophilic porous polytetrafluoroethylene sheet could allow the bubbles to pass through the sheet. We believe that these results are highly significant for providing guidance to researchers and engineers for obtaining excellent control of bubbles' behavior on a solid surface in a water medium.