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Bidirectional controllable propagation of waterborne sound holds significant importance in developing multifunctional underwater acoustic and mechanical devices. However, the existing waterborne acoustic metasurfaces have rarely explored the bidirectional sound modulations. Here, a class of Janus waterborne acoustic metasurface, enabling two‐faced arbitrarily asymmetric wavefront manipulations is reported. A three‐degree‐of‐freedom mechanical system facilitated by acoustic‐structure interaction underwater is proposed to introduce bianisotropic responses of unit cells. Monolayer ultrathin Janus metasurface is inversely designed by utilizing a function‐structure integrated topology optimization framework. Distinct underwater acoustic functionalities, including axial and oblique focusing, beam splitting, and sound diffusion, are successfully demonstrated. Underwater experiments are further conducted to validate the concept of Janus metasurface. The good consistency between experimental and simulated results confirms the excellent two‐faced asymmetric acoustic focusing performance. The proposed Janus metasurface opens up a new dimension for designing advanced waterborne acoustic devices with two‐faced multifunctional wavefront manipulations. [ABSTRACT FROM AUTHOR]

Exceptional point (EP), a special degeneracy in non‐Hermitian systems, has exhibited various distinctive wave characteristics. However, the conventional synthesis of scattering EPs in acoustics is confined to rather limited methods for breaking Hermiticity, typically requiring intrinsic losses or open interfaces. Here, the concept of synthesizing scattering EPs is theoretically and experimentally demonstrated by leveraging a metasurface with fluid‐solid interaction (FSI) in water. The incorporation of FSI offers a novel mechanism to customize natural radiation losses. Simulations and experiments consistently confirm that synthesized EPs result in extremely asymmetric scattering patterns, even in the case of spatially impenetrable metasurfaces. This enhanced spatial symmetry breaking benefits from the FSI on the interface and the nonlocal interaction between unit cells. The proposed non‐Hermitian framework, involving the interplay of sound in fluids and solids, is expected to open up new possibilities for exploring unique non‐Hermitian physics and underwater acoustic applications. [ABSTRACT FROM AUTHOR]

The acoustic impedance mismatch between water and air limits the acoustic communication through the water–air interface. Here, based on the resonances of bubbles, we propose a metasurface consisting of bubbles sealed with membranes for perfect sound transmission at the water–air interface. We have experimentally achieved sound transmission enhancement of over 20 dB at 380–510 Hz, with the thickness of the metasurface about 1/180 times air wavelength. By flexibly adjusting the immersion depth, the metasurface is able to operate at multiple frequencies. The effects of viscosity and geometry of bubbles are discussed simulatively. The present work is relevant to the practical design of advanced acoustic devices for transmedia communication. [ABSTRACT FROM AUTHOR]

Extreme impedance mismatch causes sound insulation at water–air interfaces, limiting numerous cross‐media applications such as ocean‐air wireless acoustic communication. Although quarter‐wave impedance transformers can improve transmission, they are not readily available for acoustics and are restricted by the fixed phase shift at full transmission. Here, this limitation is broken through impedance‐matched hybrid metasurfaces assisted by topology optimization. Sound transmission enhancement and phase modulation across the water–air interface are achieved independently. Compared to the bare water–air interface, it is experimentally observed that the average transmitted amplitude through an impedance‐matched metasurface at the peak frequency is enhanced by ≈25.9 dB, close to the limit of the perfect transmission 30 dB. And nearly 42 dB amplitude enhancement is measured by the hybrid metasurfaces with axial focusing function. Various customized vortex beams are experimentally realized to promote applications in ocean‐air communication. The physical mechanisms of sound transmission enhancement for broadband and wide‐angle incidences are revealed. The proposed concept has potential applications in efficient transmission and free communication across dissimilar media. [ABSTRACT FROM AUTHOR]

• Discrete metasurface is proposed for water-air sound enhancement. • Excellent wide-angle transmission is observed for discrete units. • Influences of random immersion and bending effects are discussed. This study proposes a discrete metasurface for extreme sound transmission based on the impedance matching theory. The aim is to overcome the extreme mismatch of acoustic impedance at the water-air interface. By employing topology optimization, discrete unit cells with different aspect ratios are inversely designed with unitary sound transmission. The unit cell of continuous metasurface is also obtained for comparison. After analyzing the wide-angle performance of discrete unit cells, the enhancement of sound transmission of the samples at the water-air interface is experimentally measured. It is evident that the discrete metasurface significantly enhances sound transmission compared to the bare water-air interface. And the transmission amplitude is relatively larger than that of the continuous sample. Experimental results are generally agreement with numerical ones when the viscosity of the sample is considered. Furthermore, the resonate frequency shifts observed during the experiment are discussed. They can be primarily attributed to the random immersion of unit cells for discrete metasurface and the bending of continuous metasurface, respectively. The present work will greatly promote the practical application of acoustic metasurfaces in transmedia communication and sensing. [Display omitted] [ABSTRACT FROM AUTHOR]

In this paper, elastic metasurfaces composed of zigzag units are proposed to manipulate flexural waves at a deep subwavelength scale. Through the parameter optimization of the genetic algorithm, units with full transmission and full phase control can be found, while the width is only one-fifth of the wavelength. The outstanding capability of the units is explained by analyzing their wave fields. The flat and the curved metasurfaces for focusing are designed and simulated, showing excellent performance. Experimental results of the flat metasurface show that the incident wave energy at the focal point is enhanced over 6 times, verifying the simulation results. The proposed metasurfaces could be useful in the design of compact and efficient elastic devices. [ABSTRACT FROM AUTHOR]

Self-accelerating beams have applications in optic and acoustic fields due to their peculiar properties. As a promising artificial two-dimensional metamaterial, a metasurface can be used as the generator of self-accelerating beams. However, restricted by the generalized Snell's law, most research hotspots focus on flat metasurfaces. In this Letter, the generalized Snell's law on an arbitrary curved reflective surface is discussed. Then, the phase profile for the self-accelerating beams generated from the curved reflective surface is derived based on the caustic theory. The metasurface consisting of the tunable spiral path units is constructed, and numerical and experimental validations are performed. The methodology developed in the present letter extends the applications of the self-accelerating beams. [ABSTRACT FROM AUTHOR]

Hybrid Metasurfaces for Perfect Transmission and Customized Manipulation of Sound Across Water-Air Interface (Adv. Sci. 19/2023) More details can be found in article number 2207181 by Yan-Feng Wang, Yue-Sheng Wang, and co-workers. B Acoustic Metasurfaces b By utilizing hybrid impedance-matched metasurfaces floating on the water-air interface, sound waves under the water can be perfectly transmitted to the air with arbitrary desired wavefronts, such as acoustic vortex, thereby greatly improving ocean-air communication efficiency. [Extracted from the article]

Potassium perfluorooctane sulfonate (KPFOS) and sodium perfluorooctane sulfonate (NaPFOS) exhibit poor surface activities in aqueous solution at room temperature because of their high Krafft points. In this work, we attempted to increase the solubility of KPFOS and NaPFOS and consequently improve their surface activities at room temperature with sodium p-methylbenzene sulfonate (BS) and urea, which are typical hydrotropes in industrial applications. The effects of BS and urea on the surface tension of the aqueous solutions of KPFOS and NaPFOS were investigated at 25 °C. When the hydrotropes were added, the effectiveness of KPFOS and NaPFOS in surface tension reduction was greatly enhanced and KPFOS showed higher efficiency in surface tension reduction than NaPFOS. On the other hand, BS had much stronger ability than urea to reduce the surface tension of KPFOS and NaPFOS in water. In particular, with the assistance of BS the minimum surface tension of KPFOS approached 19 mN/m at 25 °C. It was worth noting that in the presence of BS, the surface tension of an apparently 'saturated' solution (i.e., with coexisting surfactant solid) continuously decreased with increasing surfactant concentration. This behavior was ascribed to enrichment of branched PFOS isomers in aqueous phase with the assistance of BS, as evidenced by high-resolution F NMR. Hydrotropes were able to recover the inherent character of KPFOS and NaPFOS as highly surface-active fluorinated surfactants by increasing the solubility of branched isomers. This is an easy way to enhance the effectiveness in surface tension reduction at room temperature for fluorinated surfactants with high Krafft points. [ABSTRACT FROM AUTHOR]

Waterborne acoustic metasurfaces (WAMs), unlike airborne acoustic metasurfaces, generally suffer from nonlocal interaction induced by the strong fluid–solid coupling. Unpredictable parasitic scattering is usually caused by nonlocal vibration coupling between solid units, thereby interfering with the prescribed sound control. In this work, we propose a loosely coupled reflective impedance WAM to realize precise manipulation of waterborne sound. A function–structure integrated topology optimization framework involving surface impedance model and vibration coupling restriction is systematically established to inversely design WAMs. Successful individual design of lossy units with multiple inclusions is realized by weakening vibration coupling of solids through local resonance. Various customized waterborne sound fields, including extraordinary beam steering with steep deflection, propagating-to-evanescent mode conversion and super-resolution near-field focusing, have been successfully implemented and demonstrated. Good agreements between the theoretical and simulated results are observed, thereby validating the feasibility and effectiveness of the design strategy. In addition, inverse-design WAMs show very good robustness to the operating frequency, incident angle and geometrical shape. Deep-subwavelength precise manipulation of waterborne sound is further achieved by the WAM with the thickness of λ / 40. The excellent performances of WAMs result from the precisely customized surface impedance distribution. The proposed strategy opens the door to practical applications of metasurfaces in the delicate and complex waterborne sound control. [Display omitted] • Surface impedance model is proposed to precisely manipulate waterborne sound. • Reflective impedance metasurfaces with fluid–solid coupling are inversely designed. • Successful individual design of units is realized by weakening vibration coupling. • Mechanism for simultaneous modulation of phase and amplitude is revealed. • High-efficiency, ultrathin, broadband and good robust metasurfaces are realized. [ABSTRACT FROM AUTHOR]

Abstract: The effects of different concentrations of sodium thiocyanate (NaSCN) on the homogeneous solution of equimolarly mixed decyltriethylammonium bromide and sodium decylsulfonate (C10NE–C10SO3) were studied by 1H NMR, surface tension and dynamic light scattering (DLS) measurements. For the system of C10NE–C10SO3, the NMR signals were greatly broadened in the micellar concentration region. However, the shape of the NMR peaks for the micellar solutions of C10NE–C10SO3, especially for those protons adjacent to headgroups, recovered to be fine-resolved with the gradual increase of NaSCN concentration. Therefore, the NMR method directly evidenced that the electrostatic attraction between the oppositely charged headgroups in the micellar solution of C10NE–C10SO3 was significantly reduced by NaSCN. The surface tension results showed that both the surface tension at critical micelle concentration (γ cmc) and the minimum molecular area in the surface adsorbed layer (A min) were remarkably increased when NaSCN was added to C10NE–C10SO3. As shown by DLS, the addition of NaSCN could significantly induce the decrease of the aggregate size of C10NE–C10SO3. Both surface tension and DLS results supported the conclusions made by NMR. [Copyright &y& Elsevier]

Summary Objective To clarify whether exanthema is related to illness severity in acute enterovirus infection in children. Methods The data of pediatric inpatients at Zhujiang Hospital during 2009–2012 with an acute enterovirus infection were reviewed retrospectively. Enterovirus infection was determined by real-time reverse transcription PCR. Clinical data were summarized and compared between cases with and without exanthema. Results A total of 780 pediatric inpatients with an acute enterovirus infection were included in this study, of whom 83 (10.6%) presented no exanthema. The percentage of deaths in the group of patients without exanthema was significantly higher than that in the group with exanthema (7.2% vs. 1.1%; p = 0.002). Central nervous system involvement (41.0% vs. 30.0%; p = 0.041), severe central nervous system (CNS) involvement (21.7% vs. 11.0%; p = 0.005), severe CNS involvement with cardiopulmonary failure (9.6% vs. 2.3%; p = 0.002), an altered level of consciousness (15.7% vs. 7.6%; p = 0.013), and convulsions (14.4% vs. 6.3%; p = 0.007) occurred significantly more frequently in the group without exanthema. Conclusions A considerable proportion of children with an acute enterovirus infection in Guangdong Province, China during 2009–2012 presented no exanthema, and the absence of exanthema was found to be related to death and illness severity for these acute enterovirus infections. Clinicians in China should consider enterovirus as the possible pathogen when treating children with an acute pathogen infection without exanthema. [ABSTRACT FROM AUTHOR]

Acoustic metasurfaces can reshape a reflected wavefront rather arbitrarily, despite being much thinner than the wavelength, thus allowing on-demand wavefront modulation in a variety of applications. Recent passive metasurfaces, however, have suffered from bandwidth limitations, thus restricting their range of operation. In this work, we propose the systematic design of ultra-broadband passive metasurfaces by combining the broadband local reflection rule with an optimization method. The validation of the technique is demonstrated by fabrication and measurement of an ultra-broadband carpet cloak. Numerical and experimental results show that the relative bandwidth of the optimized carpet cloak, thinner than one fifth of the maximum wavelength, can exceed 93.33%, a value that is much larger than that of previous passive metasurfaces. Furthermore, multi-frequency pulse incidence tests reveal the excellent time-domain broadband characteristics of the metasurface over a wide range of angles of incidence. The proposed strategy opens a new route for the design of advanced passive metasurfaces for ultra-broadband wave manipulation and thus promotes practical applications of broadband acoustical devices. Unlabelled Image • An inverse optimization is proposed to design ultra-broadband passive metasurfaces. • More than 93% relative bandwidth is experimentally and numerically verified. • Time-domain broadband characteristic over a wide-angle range is revealed. [ABSTRACT FROM AUTHOR]

Summary Some viruses, including certain members of the enterovirus genus, have been reported to cause nephrotic syndrome. However, no case of coxsackievirus A16 (CVA16)-related nephrotic syndrome has been reported so far. We describe a case of CVA16-related hand, foot and mouth disease presenting with nephrotic syndrome in a 3-year-old boy. This is the first report of CVA16-related nephrotic syndrome. [ABSTRACT FROM AUTHOR]

The surface tension of dialkylammonium perfluorooctanoate [C 7 F 15 COONH 2 (C n H 2 n +1 ) 2 , n = 1–4], dialkylammonium perfluorooctylsulfonate [C 8 F 17 SO 3 NH 2 (C n H 2 n +1 ) 2 , n = 1–4] and trialkylammonium perfluorooctylsulfonate [C 8 F 17 SO 3 NH(C n H 2 n +1 ) 3 , n = 1–4] in aqueous solution was measured by drop volume method at 25 °C. The critical micelle concentration (cmc), the surface tension at cmc ( γ cmc ), the maximum amount adsorbed ( Γ max ) and the minimum molecular area ( A min ) in the surface adsorption layer were obtained. Because of the limited solubility for C 7 F 15 COONH 2 (C 4 H 9 ) 2 , C 8 F 17 SO 3 NH 2 (C 4 H 9 ) 2 and C 8 F 17 SO 3 NH(C 4 H 9 ) 3 at 25 °C, their cmc and γ cmc values could not be successfully obtained. Combining with other series in previous works, an overview picture for the effects of organic ammonium counterions on anionic fluorinated surfactants could be drawn. The rules for the interactions between organic ammonium ions and surfactive anions were summarized (including headgroup type, the chain length of fluorinated hydrophobic tail, and the substituent number, the alkyl chain length and the presence of hydroxyl groups in counterion structure). The mechanism behind these rules was discussed in detail, relying on the electrostatic, hydrophobic and steric factors. [ABSTRACT FROM AUTHOR]

[Display omitted] • Large-scale field experiments demonstrate the ultra-wide first bandgap. • Achieve a first bandgap with relative bandwidth of 1.17. • Study the characteristic of the first bandgap by using complex band structures. Seismic metamaterials (SMs) are expected to assist or replace traditional isolation systems owing to their strong attenuation of seismic waves. In this work, a one-dimensional inverted T-shaped SM (1D ITSM) composed of arrays of inverted T-shaped structures on a half space is proposed, which have an ultra-wide first bandgap (FBG) from 6.7 to 17.2 Hz. We find that the FBG is composed of two parts; part 1 with surface evanescent waves from 6.7 to 11.0 Hz and part 2 with no surface modes from 11.0 to 17.2 Hz by using the complex band structures. The propagation of seismic surface waves in the 1D ITSM is different in these two frequency ranges of the FBG. In part 1, the seismic surface waves are significantly attenuated in the 1D ITSM because of the surface evanescent waves, while in part 2, the surface waves are converted into bulk waves because surface waves cannot exist in the ITSM. Finally, the ultra-wide FBG is verified by using a kind of the two-dimensional ITSM in large-scale field experiments. [ABSTRACT FROM AUTHOR]

Background: Enterovirus (EV)-related hand, foot, and mouth disease/herpangina (HFMD/HA) has been prevalent in Guangdong Province, China, since 2010.Methods: Clinical data for EV-related HFMD/HA inpatients admitted to the Department of Paediatrics of Zhujiang Hospital from 2010 to 2013 were retrospectively reviewed. The corresponding EV serotypes were also determined by reverse transcription-polymerase chain reaction or BLAST analysis of the sequenced partial lengths of the viral protein1/5'-untranslated region.Results: A total of 867 eligible inpatients admitted during 2010-2013 were included in the study. Of these, the serotype of the responsible EV was successfully identified in 824 cases. The incidence of enterovirus 71 (EV71) infection amongst pediatric HFMD/HA inpatients decreased dramatically from 55.5 % in 2010 to 8.1 % in 2013, with a similar decrease recorded for coxsackievirus A16 (CVA16). However, the incidence of non-EV71/CVA16 infection increased from 30.0 % in 2010 to 83.8 % in 2013. We noted that the types of infection caused by different EV serotypes varied: EV71 was responsible for 100 % of the paralysis cases (26/26), 84.6 % of the deaths (11/13), and 84.1 % of cases with severe central nervous system involvement (SCNSI) (74/88); echovirus contributed to 16.4 % of the deaths (2/13) and 4.4 % of the SCNSI cases; and coxsackievirus accounted for only 2.2 % of the SCNSI cases (2/90). The clinical features of HFMD/HA cases varied greatly during the time period examined, with drastic changes in the hospitalization rates (45.1, 63.7, 36.4, and 19.1 % for 2010, 2011, 2012, and 21013, respectively), mortality rates (2.3, 0.9, 2.5, and 0.0 %, respectively), paralysis (5.1, 1.2, 5.4, and 0.0 %, respectively), SCNSI (16.8, 7.1, 12.7, and 2.2 %, respectively), and acute respiratory infection (21.1, 22.0, 45.9, and 59.0 %, respectively).Conclusions: The incidences of infection caused by different EV serotypes, along with the clinical features of HFMD/HA cases, changed drastically in Guangdong Province, China, from 2010 to 2013, with the biggest changes observed in 2013. The changed constituent ratios of the different EV serotypes might therefore be responsible for the differences in the observed clinical features of HFMD/HA during this period. [ABSTRACT FROM AUTHOR]

Background: A series of complications caused by enteroviruses, including meningitis, encephalitis, acute flaccid paralysis, acute cardiopulmonary failure, respiratory infection, and myocardial injury have been reported in hand, foot and mouth disease/herpangina (HFMD/HA). However, the complication of diarrhoea caused by enteroviruses has been neglected, and a summary of its clinical features and impact on HFMD/HA is unavailable.Methods: We included inpatients with HFMD/HA admitted to the Paediatric Department of Zhujiang Hospital during 2009-2012. We summarised and compared clinical data for cases with and without diarrhoea, and determined enterovirus serotypes by reverse transcriptase polymerase chain reaction and genotyping based on a partial-length fragment of viral protein 1 or the 5'-untranslated region.Results: There were 804 inpatients with HFMD/HA and 28 (3.5%) presented with diarrhoea. Gastrointestinal symptoms were mild in most cases of diarrhoea (82.1%), with high prevalence of no dehydration (82.1%), short duration of diarrhoea (78.6%) and watery stools (75.0%). The prevalence of multi-organ dysfunction syndrome (10.7 vs 0.40%) (p = 0.001), hepatic injury (14.3 vs 3.4%) (p = 0.019), myocardial injury (21.4 vs 6.1%) (p = 0.002) and convulsion (21.4 vs 7.2%) (p = 0.016) was significantly higher in the diarrhoea than no diarrhoea group. There was no significant difference between the two groups regarding prevalence of death, altered consciousness, paralysis, central nervous system involvement, or acute respiratory infection.Conclusions: Most patients with diarrhoea caused by enteroviruses circulating in Guangdong Province in 2009-2012 had mild or moderate gastrointestinal symptoms. Although enterovirus-related diarrhoea caused additional multi-organ dysfunction syndrome, hepatic injury and myocardial injury in children with HFMD/HA, timely intervention efficiently reduced disease severity and improved outcome. [ABSTRACT FROM AUTHOR]