Staphylococcus aureus (MSSA) ocular infections in Taiwan and compared them between community-associated (CA) and health-care-associated (HA) infections. We collected S. aureus ocular isolates from patients at Chang Gung Memorial Hospital between 2010 and 2017. The infections were classified as CA or HA using epidemiological criteria, and the isolates were molecularly characterized using pulsed-field gel electrophoresis, multilocus sequence typing, and Panton-Valentine leukocidin (PVL) gene detection. Antibiotic susceptibility was evaluated using disk diffusion and an E test. A total of 104 MSSA ocular isolates were identified; 46 (44.2%) were CA-MSSA and 58 (55.8%) were HA-MSSA. Compared with HA-MSSA strains, CA-MSSA strains caused a significantly higher rate of keratitis, but a lower rate of conjunctivitis. We identified 14 pulsotypes. ST 7/pulsotype BA was frequently identified in both CA-MSSA (28.3%) and HA-MSSA (37.9%) cases. PVL genes were identified in seven isolates (6.7%). Both CA-MSSA and HA-MSSA isolates were highly susceptible to vancomycin, teicoplanin, tigecycline, sulfamethoxazole–trimethoprim, and fluoroquinolones. The most common ocular manifestations were keratitis and conjunctivitis for CA-MSSA and HA-MSSA, respectively. The MSSA ocular isolates had diverse molecular characteristics; no specific genotype differentiated CA-MSSA from HA-MSSA. Both strains exhibited similar antibiotic susceptibility.This study analyzed the clinical features and molecular characteristics of methicillin-susceptible  Staphylococcus aureus is a major isolated bacterial pathogen that causes various infections in humans [S. aureus is typically categorized as methicillin resistant or methicillin susceptible based on its susceptibility to methicillin. Methicillin-resistant S. aureus (MRSA), a strain resistant to all β-lactam antibiotics, warrants particular attention because of its potentially limited treatment options and its increasing prevalence [n humans . S. aureevalence . MRSA haevalence . HA- andevalence ,4.S. aureus (MSSA) infections are more prevalent than MRSA infections [Although MRSA has received considerable research attention, methicillin-susceptible fections . Accordifections . In addifections . Howeverfections ,8,9,10, fections . Thus, dS. aureus is the most common cause of bacterial keratitis  and conjunctivitis  [S. aureus isolates were MSSA [S. aureus ocular infections [p = 0.040). In our subsequent research, we focused solely on MRSA ocular infections [fection) ,13. Althere MSSA , studiesfections  and obsefections  and perffections . Becausep = 0.006 and <0.001, respectively). Regarding local risk factors, a significantly higher proportion of the patients with HA-MSSA had a history of ocular surgery, and a significantly higher proportion of the patients with CA-MSSA used contact lenses. Keratitis was the most common ocular disease caused by CA-MSSA, followed by conjunctivitis; however, this order was reversed in the HA-MSSA group . Most of the patients with CA-MSSA received outpatient or emergency department treatment (69.6%), whereas most of the patients with HA-MSSA infection received inpatient treatment (56.9%).During this 8-year study period, MSSA strains were isolated from 104 patients. Of the 104 patients with MSSA, 46 (44.2%) were classified as having CA-MSSA, and 58 (55.8%) were classified as having HA-MSSA. SA group . The ratn = 2), ST59, ST338, ST6426, and ST672, as well as one untypeable isolate ( isolate . p = 0.047)  and fluoroquinolones. The CA-MSSA and HA-MSSA strains exhibited similar antibiotic susceptibility levels, except for susceptibility to erythromycin  .Few studies have explored the clinical and molecular characteristics of MSSA infections, particularly ocular infections. In this study, we investigated the clinical and microbiological characteristics of MSSA ocular infections in Taiwan and compared them between CA-MSSA and HA-MSSA ocular isolates, which have rarely been compared in previous studies. We observed that over half of MSSA ocular infections were HA. Keratitis and conjunctivitis accounted for most of the clinical manifestations of the MSSA ocular infections; significantly more patients with CA infections presented with keratitis, whereas those with HA infections more often presented with conjunctivitis. The molecular characteristics of the MSSA isolates were relatively diverse, and no specific genotype differentiated CA-MSSA from HA-MSSA. The antibiograms of the CA-MSSA and HA-MSSA isolates were similar.S. aureus ocular infections [In this study, a higher rate of HA-MSSA than of CA-MSSA was observed in the MSSA ocular isolates (55.8%), which is consistent with the findings of our previous 10-year study on fections  but contfections . As expeS. aureus is the leading cause of bacterial keratitis and is the most common pathogen isolated from patients with conjunctivitis [ctivitis ,13. Maractivitis . Our prectivitis  and the ctivitis .p = 0.064) among pediatric patients, other research on adult patients [S. aureus ocular isolates in the US, and both studies have demonstrated the polyclonality of MSSA ocular isolates. However, Peterson et al. reported that two major USA clonal complexes, CC5 and CC8, were the most frequently detected clones among MSSA and MRSA keratitis isolates. This discrepancy in the molecular characteristics of MSSA ocular isolates indicates geographic variation.Regarding molecular characteristics, the MSSA isolates in this study were polyclonal, and none of the clones exhibited significant differences between the CA and HA isolates. Our study revealed that ST7/pulsotype BA, ST15/pulsotype F, and ST188/pulsotype AX accounted for half of the isolates, which is consistent with the findings of previous studies on MSSA nonocular infections in Taiwan ,19. Howepatients  did not patients  and Petepatients  have invPVL, a bicomponent pore-forming toxin targeting phagocytic leukocytes, is regarded as a marker of CA-MRSA. In this study, we identified PVL genes in seven MSSA isolates 6.7%). The low prevalence of PVL-positive MSSA strains is comparable to that observed in a global clinical trial , which r%. The loIn the present study, the HA-MSSA and CA-MSSA isolates both exhibited high susceptibility to most of the tested antibiotics except for clindamycin and erythromycin. The antibiograms of the MSSA ocular isolates were determined to parallel those of nonocular MSSA isolates in Taiwan. We tested the isolates’ antibiotic susceptibilities to fluoroquinolones, the first-line treatment of ocular infections, and observed that the susceptibility rates to fluoroquinolones all exceeded 90%. This rate is higher than that (approximately 80%) reported by Asbell et al. in their study on MSSA infection in the ocular Tracking Resistance in U.S. Today (ocular TRUST) program . Taiwan’S. aureus, S. epidermidis, and Pseudomonas aeruginosa in vitro [S. aureus, S. epidermidis, and Candida species [The emergence of drug resistance necessitates innovative therapeutic approaches. Recently, new ophthalmic solutions have been developed. Povidone–iodine 0.6% was determined to exhibit higher bactericidal activity than does povidone–iodine 5% ; a commein vitro . Another species . In addi species  reportedIn contrast to the differentiation of MRSA isolates, differentiating between CA-MSSA and HA-MSSA ocular isolates is difficult. In our previous study on MRSA ocular infections, we found that patients with CA-MRSA ocular infections were, on average, younger and more frequently diagnosed with eyelid disorders than those with HA-MRSA infections . The domS. aureus is a common colonizer of the ocular surface. However, all the isolates included in this study were clinical samples collected from patients with active ocular infections. Finally, this study was conducted in a single tertiary-care hospital; therefore, the results might not be generalizable to other populations. However, because our hospital is the largest referral hospital in Taiwan, the results of this study may still generally reflect the epidemiology of MSSA infection. Additional prospective studies involving patients from more hospitals are warranted.Our study has several limitations. First, although the isolates were prospectively collected, the clinical data were retrospectively reviewed. Therefore, the patients might have been misclassified due to incomplete evaluation of risk factors. Nevertheless, we were still able to observe some significant differences between the patients infected with the CA and HA-MSSA isolates. Second, the sample size might not have been sufficiently large, but the correlation between pulsotypes and STs is similar to that recorded in the study on pediatric MSSA infection in Taiwan . Third, The study adhered to the tenets of the Declaration of Helsinki and was approved by the Institutional Review Board (IRB) of Chang Gung Memorial Hospital (CGMH), a tertiary medical center in Taoyuan, Taiwan (IRB 107-2346C). The requirement for written informed consent was waived due to the anonymous analysis of the data.S. aureus isolates were prospectively collected from patients with ocular infections and stored in the microbiology laboratory of CGMH. The medical records of the patients were retrospectively reviewed for demographic and clinical information. If more than one isolate was collected from a single patient, only the first was included for analysis. The MSSA infections were classified as HA or CA based on the definitions employed by the CDC since 2000 [From 1 January 2010 to 31 December 2017, clinical nce 2000 . The cliThe patients’ underlying conditions and ocular histories were recorded. The underlying conditions that we screened for were diabetes mellitus, hypertension, pulmonary disease, renal disease, liver disease, malignancy, immunodeficiency, current infection, recent antibiotic use, and alcoholism; we also screened for recent antibiotic use. The ocular histories included contact lens use, ocular surface disease, surgery, and trauma.Based on the ocular structures involved, the manifestations were categorized into seven diagnoses: lid disorder, conjunctivitis, keratitis, endophthalmitis, wound infection, lacrimal system disorder, and others . If a patient was diagnosed with more than one ocular infection, the primary pathology or the most severe diagnosis was chosen.Molecular analysis methods employed in this study included PFGE by SmaI digestion, PVL gene detection, and MLST, with approaches consistent with those described in detail by Lina et al.  and EnriWe evaluated the antimicrobial susceptibility of the MSSA isolates to antibiotics  through the disk diffusion method according to the Clinical and Laboratory Standards Institute’s standards for antimicrobial susceptibility testing . An E tep value of less than 0.05 was considered statistically significant.All statistical analyses were performed using SPSS . The nominal variables were analyzed through a chi-square test, and the continuous variables were analyzed using Student’s t test. The variables are presented either as a mean ± standard deviation or as a percentage. The correlation between clinical presentations and the classification of MSSA infections as HA or CA was measured using Fisher’s exact test. A two-tailed More than half of the MSSA ocular infections included in this study were classified as HA-MSSA. CA-MSSA caused a higher rate of keratitis than did HA-MSSA, whereas HA-MSSA caused a higher rate of conjunctivitis. Although the molecular characteristics of the MSSA isolates indicated that the isolates were genetically diverse, ST7, ST15, and ST188 were frequently observed in the MSSA ocular infections. Both CA- and HA-MSSA strains exhibited high susceptibility to fluoroquinolones in Taiwan. Physicians should be familiar with the epidemiology, spectrum of diseases, and antibiotic susceptibility patterns of MSSA ocular infections in their local areas. Although we could not clearly differentiate HA-MSSA from CA-MSSA in this study, the results provide information that may be used to enhance local public health policy as well as knowledge on epidemic MSSA clones worldwide. Further research should include larger sample sizes and involve more hospitals to deepen the understanding of the molecular characteristics and clinical features of MSSA ocular infections.


Mean serum lysozyme levels was 39.92 ± 55.5 mg/L in the ocular sarcoidosis group versus 10.5 ± 5.8 mg/L (p ≤ 0.0013) in the control group (n = 30). Both tests were elevated in 8/37 (21.6%) patients, elevated ACE and normal lysozyme was noted in 2/37 (5.4%) patients, whereas the proportion of normal ACE/elevated lysozyme was much higher, 23/37 (62.2%). In 4/37 (10.8%) patients, both tests were normal. The mean score of polyclonal activation (N of elevated CF serologies divided by number of viruses to which a patient was exposed) was 0.6 ± 0.33 in the ocular sarcoidosis group versus 0.15 ± 0.2 for the control group (n = 42) (p ≤ 0.00001). Sensitivity and specificity of ACE and lysozyme were, respectively, 27%/96.6% and 83.7%/90%. Sensitivity and specificity of polyclonal antibody activation amounted to 70%/90.4% Conclusion: Lysozyme was found to be much more useful than ACE as a laboratory test to support the diagnosis of ocular sarcoidosis. As shown in a previous study, polyclonal antibody activation appears to be another useful laboratory test supportive of the diagnosis of ocular sarcoidosis.Background: The diagnosis of ocular sarcoidosis (OS) is difficult to establish in the absence of manifest systemic involvement. To help clinicians reach a diagnosis, we convened a group of experts in 2006 ) to set-up clinical criteria for the diagnosis of ocular sarcoidosis. In addition, laboratory investigational tests represent a much-needed adjunct to ascertain the diagnosis. However, many of these tests have low sensitivity and specificity. Purpose: The aim of our study was to evaluate the usefulness of serum ACE, serum lysozyme and polyclonal antibody activation in the diagnosis of ocular sarcoidosis and compare the frequency of increased serum levels of lysozyme and ACE in proven ocular sarcoidosis or in suspected ocular sarcoidosis. Methods: Serum ACE and lysozyme were assessed in these two groups and their means compared to a group of non-granulomatous  uveitis patients. The proportion of elevated serum ACE versus lysozyme was compared in the sarcoidosis patients. Polyclonal antibody activation was measured by establishing exposition of patients to four human commensal herpesviruses  using ELISA or immunofluorescence and in parallel by performing quantitative complement fixation (CF) serologies. The ratio of elevated CF to positive ELISA/immunofluorescence serologies was calculated. The mean of ratios  was compared between ocular sarcoidosis and control groups. Results: Thirty-seven patients (F24/M13) were included in our study including 17 patients with IWOS Level 1 and 2 criteria qualifying for Group 1 (proven sarcoidosis) and 20 ocular sarcoidosis suspect patients. Mean age was 54.52 ± 23.74. Mean serum levels of ACE was 49.17± 29 IU/L in the ocular sarcoidosis group versus 27.4 ± 15.34 IU/L ( The diagnosis of ocular sarcoidosis is difficult to establish. It was the aim of the organization of the International Workshops on Ocular Sarcoidosis (IWOS) to set diagnostic criteria in order to facilitate the diagnosis of ocular sarcoidosis. The first IWOS was held in Tokyo in 2006 and resulted in a set of clinical criteria for the diagnosis of ocular sarcoidosis . DespiteWe included patients with ocular sarcoidosis according to the modified IWOS criteria in a retrospective fashion. Patients were divided into two categories: (1) proven ocular sarcoidosis patients; and (2) ocular sarcoidosis suspect patients. The first category of patients corresponded to Levels 1 and 2 of the IWOS criteria, i.e., biopsy proven sarcoidosis patients with a compatible uveitis (IWOS Level 1) or patients with a compatible uveitis, where the chest X-ray or CT scan revealed the presence of bilateral hilar lymphadenopathy (BHL) and/or parenchymal peri-lymphatic micronodular pattern (IWOS Level 2). mutton-fat KPs ; (2) iris nodules at the pupillary margin (Koeppe) or in the iris stroma (Busacca) ; (3) tra; (7) opt. Items 1The levels of serum ACE and lysozyme were evaluated.Serum ACE activity was measured using FAPGG (N-[3-(2-furyl) acryloyl]-L-phenylalanyl-glycylglycine; Sigma-Aldrich) with a Buhlmann kit . Normal Serum lysozyme activity was measured by using radial immunodiffusion  , with NAThe means of serum ACE and lysozyme values in the ocular sarcoidosis groups (proven and suspected) were compared to a control group of non-granulomatous uveitis (pars-planitis and HLA B27 related uveitis) for which these tests had been performed as part of the work-up before the final diagnosis was known. The control groups were chosen based on the availability of each test.Furthermore, patients were classified into four groups regarding elevation of both tests to compare their proportion: (1) both tests normal; (2) ACE elevated, lysozyme normal; (3) ACE normal, lysozyme elevated; and (4) both tests elevated.Compensatory increase of immunoglobulins as a result of decrease of T cell activity in sarcoidosis has been published in many reports ,4,5,6,7.n = 30 mean age was 41 ± 11.3, n = 47 mean age was 45.2 ± 17.6 and n = 42 mean age was 45.4 ± 17).Among the 1130 patients seen from 2005 to 2020, 168 patients (14.8%) were diagnosed as possible ocular sarcoidosis patients. Applying the inclusion criteria defined in the previous section, 37 patients  could be included . Mean age was 54.52 ± 23.74. The control group mean age was variable  in the control group (n = 30). Mean serum lysozyme levels were 39.92 ± 55.5 mg/L in the ocular sarcoidosis group versus 10.05 ± 5.88 mg/L (p ≤ 0.0013) in the control group (n = 47) (Mean serum levels of ACE were 49.17± 29 IU/L in the ocular sarcoidosis group versus 27.4 ± 15.34 IU/L ((n = 47) .n = 17) presented an ACE level of 46.69 ± 23 IU/L and a lysozyme level of 43± 67 mg/L. The group with suspected sarcoidosis (n = 20) presented an ACE level of 56.93 ± 32.21 IU/L (p = 0.2603 student’s t test comparing to group of proven sarcoidosis) and a lysozyme level of 37.69 ± 47.87 mg/L .The group with proven sarcoidosis (The proportion of ACE and lysozyme of patients having both tests elevated was 9/37 (24.3%) . The pron = 42) (p ≤ 0.00001), showing a large statistically significant difference of increase of polyclonal activation in the ocular sarcoidosis group.The mean score of polyclonal activation was 0.6 ± 0.33 in the ocular sarcoidosis group versus 0.15 ± 0.2 for the control group (n = 17) presented a polyclonal activation ratio of 0.508 ± 0.356. The group with suspected sarcoidosis (n = 20) presented a polyclonal activation at 0.674 ± 0.28  was 86.6% and Negative Predictive Value (NPV) was 77.5% .Ocular sarcoidosis has a heterogenous presentation rendering diagnosis sometimes difficult. A combination of clinical signs, investigational and laboratory tests with the highest possible sensitivities and specificities has to be sought to achieve the highest probability of correct diagnosis. At present, paraclinical investigations are far from being satisfactory. Therefore, a combination of multiple tests is performed to increase the accuracy of diagnosis. Recent studies have been published proposing new potentially more specific and sensitive biomarkers for sarcoidosis such as soluble interleukin-2 receptor (sIL-2R)  or the eOn the contrary, high serum lysozyme was newly included as a criterion separate from ACE for the diagnosis of ocular sarcoidosis in the revised IWOS diagnostic criteria in 2017  and BaarAnother limitation of the usefulness of ACE serum levels as diagnostic test for OS is the abolition of ACE serum activity in patients taking angiotensin-converting enzyme inhibitors (ACEIs) to treat systemic hypertension.  ACE leve.Finally, additional investigational tests are certainly welcome. In a previous study, we found that the role of polyclonal antibody activation of four human commensal herpesviruses, as a result of decrease of T cell activity captured in sarcoidosis granulomas, appeared as a useful marker for the diagnosis of ocular sarcoidosis . Indeed,Ocular sarcoidosis should be considered in the differential diagnosis of any ocular inflammation, especially if granulomatous signs are present, and a laboratory test can be helpful to obtain a more certain diagnosis. Lysozyme seems to be more helpful than ACE in the diagnosis of ocular sarcoidosis. Polyclonal antibody activation to herpes viruses is another useful biomarker.


As communication technology is entering the 6G era, a great demand for high-performance devices operating in the terahertz (THz) band has emerged. As an important part of 6G technology, indoor communication requires multi-beam steering and tracking to serve multi-users. In this paper, we have designed a graphene metasurface that can realize multi-beam steering for directional radiations. The designed metasurface consists of graphene ribbons, dielectric spacer, and metal substrate. By designing the graphene ribbons and controlling the applied voltage on them, we have obtained single-, double-, and triple-beam steering. In addition, we have also numerically calculated the far-field distributions of the steered multi-beam with a diffraction distance of 2 m. Our design has potential applications in future indoor directional 6G communications. Future 6G wireless communication systems have already attracted tremendous attention ,2. TerahDirectional radiation is a key component in terahertz communication systems. There have been several different techniques previously employed to develop multi-beam patterns in different spectra, involving the use of phased array antennas ,8, gradeIn this paper, we designed a tunable graphene metasurface for far-field multi-beam steering and directional beam propagation in terahertz communication technology. It was shown that the multi-beam steering could be engineered by choosing graphene ribbons with different widths and controlling applied voltage on them. As proofs of concept, we designed three devices for far-field beam steering: 1. steering three-beams at angles of −42°, 13°, and 42°; 2. steering two-beams at angles of −42°, 42°and −42°, 13°; 3. steering a single-beam to an angle of 42°. By studying the near-field distributions and far-field radiation patterns of the multi-beam steering, we demonstrated that our metasurfaces have excellent performances of anomalous multi-beam steering. Our work has paved the way for the application of directional indoor communication.2 layer acts as a dielectric spacer. A metal substrate works as a backside reflector. w, p, and s denote the width of graphene ribbons, the structure period, and thickness of the SiO2 layer, respectively. The metal substrate is assumed to be thick enough. Via choosing appropriate structural parameters and applied gate voltage, the designed metasurface may sufficiently interact with incident light and allows us artificially steer the wavefront of the THz beam.There is a possible application scenario presented here for indoor THz communication. As shown in σintra and σinter are related to the electron-photon scattering process within the band and the interband transition, respectively. At room temperature T = 300 K, the interband transition can be ignored due to the Pauli exclusion principle, and the conductivity of graphene can be simplified to a Drude-like model [e is the electron charge, EF is the Fermi energy level, ћ is the Planck constant, τ is the relaxation time, which is 10−12 s in this work [t is the thickness of the graphene which is 0.35 nm in this work, ε0 is the permittivity of free space. From the above equations, it is clear that the Fermi energy level of graphene can be easily modulated by the gate voltage [fv = 106 m/s, and V is the applied electric potential. So once we know the Fermi energy level of graphene, we can determine the corresponding voltage according to the formula. Due to the tunability of permittivity of graphene, we can achieve dynamic modulation of the beam deflection by designing a metasurface with a specific phase profile.To investigate the designed structure, numerical simulations have been performed. In our model, the graphene ribbons are treated as 2D conductors. Its optical properties can be described by the conductivity uctivity :(1)σg=σike model :(2)σ(w)=his work ,42,43. Whis work :(3)ε(w)= voltage . In genew) and the thickness of the dielectric layer (s) change, respectively. In these cases, the Fermi energy level of graphene is 0.64 eV. The refractive index of SiO2 is 1.4 [p) is 3 μm. The drude model is applied to describe the optical property of a gold-backed reflector with a thickness of 2 μm. The light source is a normal incidence with TM polarization. When the width of the graphene ribbon is near 1 μm, the reflection amplitude varies significantly and phase change almost covers 0–2π, showing the characteristic of plasmon resonance. It can be also observed that the reflectivity and reflection phase will change periodically with the dielectric layer thickness, which may be attributed to Fabry−Perot resonance in the dielectric layer. Herein, we can treat the designed structure as an asymmetric Fabry−Perot resonator, where the graphene ribbons and metal substrate act as front and back reflectors, respectively. According to these results, we can choose a dielectric layer with specific thickness regarding the required reflectivity and reflection phase.As a proof of concept, we designed a metasurface to operate at 12.32 THz. The operating frequency of the proposed graphene metasurface can be easily reduced by scaling the size of the graphene metasurface as graphene strongly interacts with an electromagnetic wave with low loss in the terahertz regime. We used the finite element method to simulate the performances of the unit cell and the designed metasurfaces. 2 is 1.4 , and the2 layer thickness of 3 μm. w) and Fermi energy level of the graphene ribbon, respectively. Due to the Fabry–Perot resonance between graphene ribbons and metal substrate, the continuous 2π phase modulation of reflection can be achieved, further demonstrating the desired metasurface can be constructed by simply choosing the values of w and FE.In this work, we chose the SiOni denotes the refractive index of the medium in the incident region, iθ is the angle of incidence, rθ is the angle of reflection. When the incident light is normally incident and the refractive index of the medium in the incident region in = 1, the reflection angle can be written as:Based on the results above, we can achieve deflection of the reflected beam at the frequency of 12.32 THz. The designing of the metasurface is mainly based on the generalized Snell’s law, in which phase gradient  formula :(4)sin(θAccording to Equation (5), the reflection angle, i.e., the beam steering direction is related to the phase gradient when the incident wavelength is determined. We may achieve multi-beam steering for directional radiations as if we introduced different phase gradients to the metasurfaces. Using this concept, we designed a metasurface to control the normal incident waves and generate multi-beam reflections. We chose 102 graphene ribbons with a period of 3 μm. For the normal incident TM polarized light frequency of 12.32 THz, we first implemented three kinds of phase gradients of −π/6, π/18, and π/6 with 26, 37, and 39 unit cells, respectively. Therefore, the theoretical deflection angles are −42°, 13°, and 42°, which can be calculated from Equation (5). The unit cells are selected appropriately to achieve corresponding phase shifts according to Ex, we can easily see the anomalous reflection of the two asymmetric beams at the directions with angles of about −42° and 13°. Similarly, by selecting 102 graphene ribbons with a phase gradient of π/6, we achieved a single beam deflection with an angle of about 42°, as shown in FE. From When we fix the structure parameters in In the following, we calculated the far-field radiation patterns of our designed metasurfaces. Bandwidth is a key feature to evaluate the performance of communication devices. To demonstrate, we have also simulated beam deflection in the frequency range 12–12.5 THz, and here we give the far-field radiation map for the single-beam case, as shown in E is the electric field,  are the coordinates on the metasurface plane, k0 is the wave vector of the incident light in the vacuum, λ is the incident wavelength.To demonstrate the performances of our designed metasurface, we applied Fraunhofer’s diffraction formula to simulate the amplitude distribution of multi-beam along the x-direction at a propagation distance of 2 m. The Fraunhofer formula is written as:In In summary, we introduced a dynamically tunable metasurface based on graphene ribbons for multi-user indoor communication. By properly choosing the width of the graphene ribbons, the continuous 0–2π phase coverage can be achieved. Similarly, the desired phase shift can be obtained by adjusting Fermi energy levels applied to the graphene ribbons. Simulation shows that the designed metasurface can achieve dynamic adjustable multi-beam far-field anomalous reflection. From the near field distributions and the far-field radiation patterns, we can clearly observe the deflection of three beams, two beams, and a single beam. We also numerically calculated the field distribution of multi-beams at a distance of 2 m away, and the results demonstrated that the beams are separated into beams with different propagation angles. Overall, we have designed a metasurface that provides a new method to achieve indoor directional communication.


This study provides evidence supporting the operation of a novel cognitive process of a somatic seat of attention, or ego-center, whose somatic location is under voluntary control and that provides access to differential emotional resources. Attention has typically been studied in terms of what it is directed toward, but it can also be associated with a localized representation in the body image that is experienced as the source or seat of attention—an aspect that has previously only been studied by subjective techniques. Published studies of this phenomenon under terms such as egocenter or self-location suggest that the seat of attention can be situated in various ways within the experienced body, resulting in what are here referred to as different attentional stances. These studies also provide evidence that changes in attentional stance are associated with differences in cognitive skill, emotional temperament, self-construal, and social and moral attitudes, as well as with access to certain states of consciousness. In the present study, EEG results from multiple trials of each of 11 specific attentional stances confirmed that patterns of neural activity associated with the voluntarily control of attentional stances can be reliably measured, providing evidence for a differential neural substrate underlying the subjective location of the seat of attention. Additionally, brain activation patterns for the attentional stances showed strong correlations with EEG signatures associated with specific positive emotional states and with arousal, confirming that differential locations of the seat of attention can be objectively associated with different emotion states, as implied in previous literature. The ability to directly manage the seat of attention into various attentional stances holds substantial potential for facilitating access to specific cognitive and emotional resources in a new way. Historically, the sense that there is a beam of attention emanating from oneself to the object of attention (such as a chair) was so strong in the classical era that philosophers understood it as a beam of light emanating from the eyes and reflecting back information about the object of regard. It is explicit that this beam of light/attention can be directed at will toward any object in the field of view, as is the subject of numerous attentional experiments in the modern era. Of course, such concepts are all metaphorical imagery for neural excitation processes in the brain, with a target in the neural representation of the location of objects in space, that is enhanced by a directed neural process under the voluntary control of the location of interest.egocenter or self-location, without reference to its possible importance for the study of attention. This study describes the body region where attention is directed from as the seat of attention, to distinguish it from what attention is directed toward, which is the target of attention. Just as one's perspective on objects in the environment changes while walking through a forest or down a city block, a change in the seat of attention creates a shift in attentional perspective, resulting in a different attentional stance—a variable that has been shown to affect state of consciousness, emotional temperament, self-construal, and social and moral attitudes.This kind of focal attention has typically been studied in terms of what it is directed toward, but the hypothesis for the present study is that this beam is also perceived to have an adjustable source in the body from which it emanates, like a fireman holding their hose over the shoulder or down by the waist. The body location from which attention is sensed to project—typically either the head or upper torso—has been the subject of a small number of studies under terms such as a location from which attention is directed. For this study, “seat of attention” is the preferred term. However, all previous evidence for this psychological construct has been based on subjective report of its existence and perceived location in the intrapersonal and peri-personal body space.The sense of where I am located is associated in a generalized way with my overall body's location in space, but within the body some locations are more strongly associated with the felt sense of the located self , or at the level of the upper torso, with a minority of cases near the neck or lower face  being able to move their seat of attention from one designated location within the body  to another; (b) being able to move their seat of attention to places other than the head and chest; and (c) being able to shift between focused and diffuse attentional stances at each location;Each attentional stance will show a differential scalp activation pattern;Within-participant inter-run correlations on the same attentional stance will be positive, indicating consistency in brain activity associated with each attentional stance;EEG signatures associated with attentional stances will show an increase in higher frequencies as the seat of attention is situated higher along the body's superior-inferior axis or between focused and diffused stances;The signature of some attentional stances will correlate significantly with those of positive emotions and/or affective dimensions;Attentional stances that soften the sense of boundaries or extend beyond the boundaries of the physical body will be associated with positive emotional states;Attentional stances that do not extend beyond the boundaries of the physical body will not be associated with positive emotional states;Only focused attentional stances aligned with the body midline will be strongly correlated with emotion-related arousal;Diffuse and focused stances will display inverted correlational relationships to positive emotions and arousal.Eight participants (5F/3M) with a mean age of 54 (range: 32–71) who reported facility in self-regulation of their attentional stance were measured with a 128-lead EEG array while assuming 11 specific attentional stances. The sample size is modest due to the difficulty of identifying individuals capable of rapidly moving through multiple attentional stances, which is rather more demanding than the common use of self-regulation for simplified access to meditative, embodied, or performance-related states. Experimental procedures were reviewed and approved by the California Institute of Integral Studies Human Research and Review Committee, and participants provided written informed consent.Some stances required the seat of attention to be focused in a particular body location, while in others it was required to be diffused over an extended region of body-relative space. Participants completed three 20 s trials of each attentional stance. The 127-channel EEG was recorded continuously throughout the experimental session (see below). The trial protocol was identical for each participant, except that each set of stances arranged in a different randomized sequence to eliminate order effects. Participants were instructed to assume one attentional stance at a time for 20 s, asked to indicate when each attentional stance had been achieved, marking the time at which the 20 s sample was extracted from the continuously-recorded EEG.Normally, most people in the schooled Western culture think of their attention as emanating from somewhere in the middle of the head, but different social contexts may move it to different locations in the body. For example, when dancing or listening to rock music, the seat of attention may naturally shift to somewhere in the abdomen. Experience with individuals interested in controlling their attentional stance shows that they can report moving the seat of attention to a wide range of bodily locations, and also of controlling whether it is locally focused or more broadly diffused. Inspired by a small number of published reports of self-location extending beyond the physical body , which incorporates 128 electrodes distributed around the head and face, so that the electrode net spans all regions of the scalp overlying any part of the brain . The impEEG results were analyzed by a normalized frequency-band analysis that was validated by a frequency-domain principal components analysis. One approach to frequency-based analysis is to apply a principal components analysis (PCA) to the frequency spectra across conditions to identify the primary components controlling the differential EEG activity during the attentional tasks. For this, the data were first filtered with a filter proportional to frequency (f), because EEG spectra tend to fall with a 1/f spectrum up to about 100 Hz, while the signal-to-noise ratio tends to remain roughly constant over the same range. The PCA was then computed by the Matlab Singular-Value Decomposition (SVD) function. The eight components contributing the most to the PCA variance are plotted in Inter-run correlations of the EEG frequency spectrum amplitudes were computed, for each combination of frequency band and attentional state, across the three runs for each participant. Blink artifacts were avoided by subdividing the runs into 2s epochs and restricting the inter-run correlation analysis to samples in which the epochs were blink-free.The EEG scalp patterns of 10 positive emotions and 4 related affective dimensions were measured by Hu et al.  while waFor the emotional analysis, the patterns of activation over these 32 scalp locations for each of 10 emotions and 4 affective dimensions were correlated with the patterns of activation across these locations in the present study, for each of the 11 attentional stances in each of the 5 EEG frequency band (a 14 × 11 × 5 correlation matrix).p ≤ 0.002, a level that would allow less than one false positive per frequency band.The approach taken to the group-level statistical analysis is to rely on individual significance levels for each correlation of the pattern of scalp activation for each of the 10 emotions with that in each frequency band for each of the 11 attentional stances, with correction for multiple applications. Across 32 scalp locations, this correction provides for correlations ≥0.5 being treated as significant at p < 0.001, or Bonferroni criterion of p < 0.05 corrected for 50 applications of the test). This approach combines statistical rigor with a flexible analysis capability for complex data structures. Given the sample of 8 participants, this criterion corresponds to an effect size of 1.06 for any reported result, which is well beyond Cohen's . Transitions between attentional stances typically required <1 min to achieve as indicated by the participants with a slight nod of the head following the instruction about which state to target at the beginning of each trial, including some seconds allowed for stabilization of the stance. All participants reported the ability to shift to each of the 11 different attentional stances prescribed for the study, including locations in the lower torso (Hypothesis 1b), and were able to enter both focused and diffuse attentional stances (Hypothesis 1c).Each attentional stance showed a differential pattern of scalp activation in at least one frequency band (Hypothesis 2); the average responses across the three repeats for all 127 active electrodes under the 11 attentional stances in each of 9 EEG frequency bands are shown in Multiple analytic approaches found no discernible superior-to-inferior or focused-to-diffused pattern across the EEG frequencies (Hypothesis 3), suggesting that the seat of attention is encoded elsewhere than near the somatosensory cortex. Moreover, within-participant inter-run correlations for each attentional stance were positive for all measured frequency bands. Inter-run correlations were lowest in the alpha bands but higher than 0.5 in all bands above the alpha frequencies (Largely in line with expectations (Hypothesis 6), four of the five attentional stances expected to soften the sense of boundaries through diffusion or extension beyond the bounds of the physical body were strongly correlated (≥0.5) with at least one positive emotion in one band . Only two of six attentional stances focused within the bounds of the physical body were associated with positive emotions, which was partially in line with predictions . As predicted (Hypothesis 8), the three attentional stances associated with arousal were aligned with the body midline .Figure 7; Hypothesis 9); this was also the case in the gamma band for two of these conditions . For example, when attention was focused at the core of the whole body, beta activity correlated positively with four emotions  and negatively with six emotions ; when attention was diffuse throughout the whole body, beta activity correlated in precisely the opposite way—negatively with the four emotions that showed positive correlations with the focused state, and positively with the six emotions that had negative correlations in the focused state.In three of the four conditions where a similar seat of attention was used for both a focused and diffuse attentional stance , the focused and diffused conditions correlated with positive emotions in an inverse way in the beta band . In three of the four locations of attention where both focused and diffuse stances were used, the correlation with emotion-related arousal was inverted. That is, in the beta and gamma bands three focused attentional stances  correlated positively with arousal levels associated with positive emotions, while for three corresponding diffuse attentional stances  correlations with arousal were negative to approximately the same degree.A similar inverse relationship between focused and diffuse attentional stances was observed relative to arousal . This is also the case with the diffuse attentional stances , except that as noted the profiles of diffused attentional stances are inversions of those for the focused attentional stances.Given that there were no such inverse correlations in theta, low alpha, or high alpha bands, and that focused and diffuse attentional stances situated in the chest did not show the predicted inverse correlations, Hypothesis 9 was only partly confirmed.p < 0.0001 for the 31 degrees of freedom of the scalp locations, implying no false positives over the 770 tests conducted for Of the 11 attentional stances, six showed strong positive correlations (≥0.5) in at least one frequency band with the EEG signatures reported by Hu et al.  associatThe specific positive emotions that were found to show a pattern correlation with the attentional stance patterns are tabulated in source of this attentional focus, the felt location of the perceiving self, is always at the same bodily location (such as the center of the head), or whether its felt location can be relocated under voluntary control. This study had two major goals. The first was to provide objective evidence in support of the concept that there is an identifiable seat of attention located somewhere in intrapersonal space that can be voluntarily controlled. The second was to utilize the pattern of EEG activation associated with each attentional seat, or stance, included in the study to identify the emotional tone accompanying each one.Selective attention is well-known to be directable to specific targets in the field of awareness, both exogenously and under voluntary control. What has not been previously established is whether the The results offer the first evidence that the self-regulation of this seat of attention in the felt experience of body-relative space can be used to voluntarily access specific attentional stances, and that these stances can be situated in areas of the body other than the head and chest. These attentional stances were reliably associated with specific patterns of brain activation, and activation patterns differed between stances. Attentional stances therefore appear to correlate with stable patterns of neural activity. This suggests that the construction and regulation of the seat of attention is a novel cognitive process not previously assessed.The fact that regulation of the seat of attention appears to directly affect access to emotional and cognitive resources is in line with previous findings that the subjective experience of self-location served this function  in at least one frequency band. This suggests that selection and use of attentional stances associated with different cognitive and emotional resources may offer a simplified way to access desirable mental and emotional states and their associated resources. Since participants in this study were typically able to relocate attention from one stance to another in less than a minute, self-regulation of the seat of attention may provide a rapid and efficient way to access such resources.Applications of the findings will require additional research to clarify the mechanisms by which self-regulation of the seat of attention impacts cognitive, emotional, and attentional states. However, in order to guide the development of future hypotheses it may be useful to consider ways in which attentional stances may be related to various mental states.For example, typically complex or high-performance states such as mindfulness or flow states are accessed by indirect means and learned slowly. Training in state mindfulness in a mindfulness-based stress reduction context, while effective, will often require 25–30 h of instruction plus hours of individual practice before the target state can be reliably accessed and retained, and the skill maintained. This is likely in part because the mindful state is taught through inductive learning, as a byproduct of repeated exercises in a group context where a leader is modeling the mindful state. By contrast, training based on the attentional stance of the mindfulness state could provide greatly accelerated learning and expedited access to such states.As a specific example, in Marolt-Sender's  study wiSelf-regulation of the seat of attention to head or chest locations may also provide direct access to cognitive and affective states associated with head-located or chest-located attentional stances. Evidence from prior work suggests that the seat of attention, corresponding with self-location, may be a variable in cognitive efficacy, emotional temperament, self-construal, and social and moral attitudes  for correlations between patterns of scalp activation associated with specific attentional stances and those associated with positive emotions in a different study  and significance (up to The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.The studies involving human participants were reviewed and approved by Human Research Review Committee, California Institute of Integral Studies. The patients/participants provided their written informed consent to participate in this study.GH, LL, and CT contributed to the conception and design of the study. LL and CT performed the statistical analysis and wrote the sections of the manuscript. GH wrote the first draft of the manuscript. All authors contributed to the manuscript revision, read and approved the submitted version.This work was funded from NSF/SL-CN 1640914 grant to LL.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


In a carbon-rich atmosphere, high-energy atoms bombard the Ni and Si surface, and reduce the free energy in the thermodynamic equilibrium of solid Ni–Si particles, considerably catalyzing the growth of Ni–Si nanocrystals. By controlling the carbon source content, a Ni3Si2 single crystal with high crystallinity and good homogeneity is stably synthesized. Electrochemical measurements indicate that the nanostructures exhibit an ultrahigh specific capacity of 835.3 C g−1 (1193.28 F g−1) at 1 A g−1; when integrated as an all-solid-state supercapacitor, it provides a remarkable energy density as high as 25.9 Wh kg−1 at 750 W kg−1, which can be attributed to the free-standing Ni3Si2/graphene skeleton providing a large specific area and NiOOH inhibits insulation on the electrode surface in an alkaline solution, thereby accelerating the electron exchange rate. The growth of the high-performance composite nanostructure is simple and controllable, enabling the large-scale production and application of microenergy storage devices.Recent developments in the synthesis of graphene-based structures focus on continuous improvement of porous nanostructures, doping of thin films, and mechanisms for the construction of three-dimensional architectures. Herein, we synthesize creeper-like NiThe online version of this article (10.1007/s40820-020-00527-w) contains supplementary material, which is available to authorized users. Electrical energy storage systems have become one of the key research objects that are studied to address current energy challenges such as the rapid consumption of fossil fuels, environmental pollution, and global warming , 2. Rech3S2 and Co9S8 double-size nanoparticles [3S2/carbon nanotubes [3S2@MoS2 core shell nanorods on Ni foam [2 nanocubes [3S2@Ni composites [3S2 nanorod arrays on Ni–graphene foams [2 electrodes have several disadvantages, such as low capacity, poor cycle life, large volume change rate, and solubility in electrolytes, limiting their use in supercapacitors [2 nanocube prepared via the microwave-assisted method has good cycle stability . However, the specific capacitance of the NiS2 nanocube is poor . Wang et al. [During the nanotechnology revolution of recent decades, one-dimensional nanostructures, such as nanowires, nanotubes, and nanorods, have attracted widespread attention because of their unique physical and chemical properties . The prearticles , hierarcanotubes , Ni3S2@M Ni foam , NiS2 naanocubes , Ni3S2@Nmposites , and Ni3ne foams . Howeverpacitors . For exapacitors  reportedg et al.  highligh3Si2 nanowires prepared via low-pressure chemical vapor deposition have a high specific capacitance (760 F g−1 at 0.5 A g−1) and low series resistance (0.93 Ω). By definition, high specific capacitance and low series resistance are key factors to mitigating the tradeoff between the power and energy densities. Therefore, nickel silicide can be used as a new electrode material to solve the limitations of traditional electrical double-layer capacitor materials in supercapacitor applications.Compared with other electrode materials, nickel silicide is advantageous because of its large mechanical stress tolerance, good electrical conductivity, and high electrochemical performance. It is a potential candidate material for supercapacitor electrodes. More importantly, its growth is compatible with and can be easily integrated into silicon process technology , 22. Acc3Si2/graphene using a simple and effective low-pressure all-solid melting-reconstruction chemical vapor deposition (LSRCVD) method. The Ni3Si2/NiOOH/graphene composite nanostructures were synthesized through a hydrothermal method. Based on systematic micromorphological characterization, the formation mechanism of the nanostructures is discussed to develop reliable and controllable nanostructure preparation technology. Under bombardment by high-energy particles in a carbon-rich environment, supersaturation of the Si precursor is decreased by using Ni as the substrate. The silicon vapor is cooled and crystallized on a molten nickel substrate to form Ni–Si nanostructures. By adjusting the carbon content and growth time, we successfully achieved Ni3Si2 nanocrystal growth in the axial direction and fabricated nanostructures with high surface areas under Ar gas etching. The electrochemical test confirms that the Ni3Si2/NiOOH/graphene composite exhibits extremely good performance. The specific capacitance of the Ni3Si2/NiOOH/graphene electrode reaches 835.3 C g−1 (1193.28 F g−1) at 1 A g−1. The fabricated all-solid-state supercapacitor exhibits a maximum energy density of 25.9 Wh kg−1 at 750 W kg−1. These properties are due to the following reasons: First, the Ni3Si2/graphene nanoskeleton possesses excellent mechanical strength and supports the entire electrode. Simultaneously, Ni3Si2 effectively guides the directional deposition of NiOOH with high crystal quality. NiOOH inhibits the insulation of the electrode surface in an alkaline solution and accelerates the electron exchange rate. Second, the interconnected nanostructures have large specific surface areas. Even if parts of the nanoflakes are disconnected from the substrate, the internal electronic circulation will still be protected by physical contact with adjacent nanostructures. Third, in a carbon-rich atmosphere, the surface free energy of solid Ni–Si particles in a thermodynamic equilibrium decreases and excess Ni rapidly diffuses into Ni–Si nanoparticles, which facilitates the formation of Ni–Si nanostructures. Nanoparticles grow in the radial direction to form creeper-like nanostructures. The creeper-like structure increases the specific surface area of the electrode material and the active sites, thereby inducing more redox reactions in the nickel substrate in addition to high conductivity, generating fast charge-transfer kinetics and thus better performance. Fourth, because of the self-supporting 3D porous nanostructure, electrons can traverse the entire electrode surface, creating a convenient electron transfer path for active nanomaterials, thereby improving the supercapacitor performance. The excellent electrochemical properties indicate the potential for integrated SC applications and marketization.Herein, we synthesized novel creeper-like Ni3Si2/graphene structure was fabricated using a laboratory-made low-pressure chemical vapor deposition (CVD) system. Initially, the surface of the Ni foam was sonicated in a 0.3 mol L−1 (NH4)2S2O8 solution for 5 min to remove contaminants and oxides. After washing with analytical-grade acetone, ethanol, and deionized water for 5 min each, the Ni foam was dried with nitrogen. Next, the cleaned Ni foam/Si (111) stack was placed into the quartz tube furnace of the CVD system at a base vacuum of ~ 0.1 Pa. Ultrahigh-purity hydrogen was injected into the furnace tube at a flow rate of 10 sccm. Subsequently, the nickel foam was heated from 30 to 1030 °C at a heating rate of 20 °C min−1. Once the temperature reached 1030 °C, ultrahigh-purity methane was introduced into the furnace tube (flow rate of 50 sccm) as the carbon source for 2 h. Second, the sample was cooled to 1000 °C and annealed for 1 h in a mixed atmosphere . The tube was then slowly cooled to ambient temperature at a cooling rate of ~ 5 °C min−1 under 10 sccm of hydrogen flow. Third, the Ni3Si2/NiOOH/graphene nanostructure was synthesized using a hydrothermal method. The metal foams were selectively etched in a mixture of 1 M FeCl3 and 2 M HCl at 60 °C overnight and free-standing Ni3Si2/graphene was obtained. Subsequently, 100 mg urea was uniformly dispersed in 40 mL deionized water by stirring for 1 h. The mixture was then transferred into a 60-mL Teflon-lined stainless-steel autoclave and the fabricated Ni3Si2/graphene was added to the mixture. The autoclave was subsequently sealed and maintained at 180 °C for 2 h. Once the reaction was completed, the autoclave was cooled to room temperature. Finally, the sample was clamped with tweezers and washed three times with deionized water and ethanol. The final product was obtained after drying overnight under vacuum at 80 °C. The mass of the graphene, Ni3Si2, and NiOOH are about 0.18, 0.26, and 0.26 mg, respectively. The detailed analysis process is in the supporting information.The creeper-like nanostructures were grown on commercial Ni foam in three steps. First, a hybrid Ni3Si2/graphene is similar to that of Ni3Si2/NiOOH/graphene, and the detailed process is in the supporting information.The synthesis process of NiOOH/graphene and Ni3Si2/NiOOH/graphene nanostructures were investigated via scanning electron microscopy (SEM) . The crystallinity of the materials was evaluated through high-resolution X-ray diffraction (XRD)  in Bragg (reflection) geometry and Cu Kα1 radiation (wavelength: λ = 1.54056 Å). The Raman spectrum was obtained with a Raman spectroscopy system  using an Ar+ laser (514 nm wavelength) as the excitation source. The elemental analyses of the composites were conducted via X-ray photoelectron spectroscopy (XPS) .The morphologies of the NiCyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS) were performed using the CHI660 electrochemical workstation and a three-electrode test system including the active material as the working electrode, Ag/AgCl as the reference electrode, platinum mesh as the counter-electrode, and 3 M KOH as the electrolyte.Qs (C g−1) and specific capacitance Cg (F g−1) can be computed using Eqs. (I is the discharge current (A), m is the total weight (g) and Δt is the discharge time (s).Based on the GCD curves, the specific capacity Qs C g− and specing Eqs. :1\documeAll SC cell electrochemical measurements were performed using the prepared “sandwich” capacitor. The electrodes, cellulose diaphragms, and electrodes were stacked, and the active materials were in direct contact with the current collector. The electrolyte was gelatinous PVA-KOH.Cg) of the SC cell was calculated using the GCD curves and Eq. (E is the energy density (Wh kg−1) and P is the power density (W kg−1).The specific capacitance ( and Eq. . The ene and Eq.  and 4)::Cg) of t3Si2/NiOOH/graphene nanostructures were synthesized on 3D graphene/Ni foam using a three-step method. Figure 3Si2/NiOOH/graphene nanostructures.To ensure high purity and controllability, novel creeper-like Ni4 was decomposed through catalysis with the Ni foam and the carbon atoms dissolved in the 3D Ni foam. Simultaneously, the Si vapor mixed with Ni vapor in a carbon-rich environment, the formation of Ni–Si nanocores form from supersaturation of Ni/Si vapor, the nanocore melting, cooled and then condensed on the surface of the Ni foam. Several Ni–Si nanocores formed during condensation. In the second step, carbon atoms precipitated from the Ni foam and were transferred into graphene along the 3D Ni foam surface during annealing. During melting and condensation, the Ni–Si nuclei randomly merged and flowed on the graphene surface. Then, these nuclei grew radially and axially, forming a creeper-like nanoskeleton. In the third step, several Ni3Si2 units on the surface reacted with urea during the hydrothermal process to form NiOOH nanosheets, which dissolved in the solution. Ni3Si2 acts as the nanoframework to guide the deposition of NiOOH nanosheets, and a creeper-like nanostructure forms through the complex directional adhesion process.In the first step, CH3Si2 nanostructures using LSRCVD. The way to control the carbon content is to change the Ar flow rate. In the experiment, 12.5% carbon content atmosphere includes 10 sccm H2, 50 sccm CH4, 340 sccm Ar, 6.25% carbon content atmosphere includes 10 sccm H2, 50 sccm CH4, 740 sccm Ar, and 4.17% carbon content atmosphere includes 10 sccm H2, 50 sccm CH4, 1140 sccm Ar. During annealing, Ni–Si nanocrystals start to grow; the gas flow rate strongly affects the growth of the nanostructures, as shown in Fig. 2) condensed and crystallized as the crystal nucleus on the surface of the Ni foam , the crystallization mechanism changed to predominant axial growth . Because decreased number of carbon atoms increased the required surface free energy, Ni–Si nucleation became difficult. Figure The carbon content is one of the main factors affecting the synthesis of Ni3Si2 nanostructures using LSRCVD. Figure 3Si2 nanostructures for different growth times with 6.25% carbon content. Initially, mostly incomplete nanostructures were formed. In addition, the densities of the nanostructures were low, as shown in Fig. 3Si2 nanostructure growth.The annealing time is another key factor affecting the fabrication of Ni3Si2/NiOOH/graphene) and EDS images of the Ni3Si2/NiOOH/graphene creeper-like nanostructures. The lattice fringe distances of 0.25, 0.32, 0.33, and 0.46 nm in Fig. 3Si2 structure, respectively [Figure ectively . And theectively , 24. Fig3Si2/NiOOH/graphene , respectively. Compared with that of NiOOH/graphene, the intensity of the graphene and NiOOH peaks is much stronger than that of Ni3Si2/NiOOH/graphene, which could be caused by the presence of unrepaired defects such as lattice mismatch.Typical XRD patterns of the Ni3Si2/NiOOH/graphene materials were characterized via XPS. The survey scan spectra , Ni3Si2/NiOOH/graphene-1, -2 and -3 electrodes clearly differ owing to the significant contributions from Faradaic capacitance. The considerably extended discharge time of Ni3Si2/NiOOH/graphene-2 again proves their enhanced capacitance. The Nyquist plots obtained by EIS are composed of an arc in the high-frequency region and a straight line in the low-frequency region, which can be simulated by an equivalent circuit . Obviously, Ni3Si2/NiOOH/graphene-2 has minimal series (0.28 Ω) and contact resistances (0.8 Ω), which indicates better capacitance performance. It attributed to creeper-like Ni3Si2/graphene nanostructure has smaller crystal size and higher density. Electrolyte ions fully contact with the electrode and increase the effective specific surface area, and the creeper-like Ni3Si2/NiOOH/graphene electrode provides more active sites to store energy.To determine the electrochemical performance of the positive electrode, cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS) of the Ni−1. The area of the CV curve of the electrode with Ni3Si2/NiOOH/graphene is larger than that of NiOOH/graphene and Ni3Si2/graphene, which indicates high capacitance. Notably, the three CV curves show different redox peaks at the same scanning rate because the Gibbs free energy of the surface redox reaction of Nip2/Nip3 differs. The relative redox process can be described using Eqs. (i) and scan rate (ʋ) using Eqs.  process, respectively. As shown in Fig. b values for the anode peaks in Ni3Si2/graphene and Ni3Si2/NiOOH/graphene are 0.69 and 0.59, respectively, indicating that the specific capacitances of the electrodes are based on both diffusion-controlled and pseudocapacitive behaviors. Adding NiOOH increases the size of the nanostructure and proportion of the current generated by the volume response. Therefore, the Ni3Si2/NiOOH/graphene electrode mainly exhibits diffusion control. The pseudocapacitive contribution can be investigated using the CV curves and Eqs. ::−1. The ing Eqs.  and 8)::−1. The and Eqs. :9\docume3Si2/NiOOH/graphene are shown in Fig. −1. Even at a high current density of 50 A g−1, the Coulomb efficiency can reach 86.93%. The specific capacity of the device at a current density of 1 A g−1 calculated from the discharge branch of the device is 835.3 C g−1 (1193.28 F g−1). The specific capacitance values of the electrodes were calculated based on their corresponding GCD curves, as shown in Fig. 3Si2/NiOOH/graphene electrode is much better than that of the Ni3Si2/graphene, and NiOOH/graphene electrodes because adding NiOOH provides more active sites and accelerates the ion exchange of the electrode surface in alkaline solution. The electrons react with NiOOH on the surface to generate Ni(OH)2 and OH−. Then, OH− reacts with Ni3Si2 to generate electrons and Ni3Si2(OH)3. It is a positive feedback process until the electrode material is transformed into Ni(OH)2 and Ni3Si2(OH)3. Additionally, the unique spatial structure of Ni3Si2 eases the agglomeration and deformation of NiOOH.In addition, the GCD curves of Ni3Si2/graphene, NiOOH/graphene, and Ni3Si2/NiOOH/graphene are shown in Fig. 3Si2/Graphene electrode, and Ni3Si2/NiOOH/Graphene electrode are 0.4, 0.97, and 0.36 Ω, respectively. The equivalent series resistance is 0.23, 0.28, and 0.47 Ω for the NiOOH/Graphene electrode, Ni3Si2/Graphene electrode, and Ni3Si2/NiOOH/Graphene electrode, respectively. Ni3Si2/NiOOH/graphene has the largest equivalent series resistance, which is due to the lattice mismatch at the interface of Ni3Si2 and NiOOH. In an alkaline environment, a protective layer of SiO2·2H2O and/or Ni2SiO4 can form on the surface of Ni3Si2. Because Ni2SiO4 and SiO2·2H2O are insulators, the charge transfer and diffusion processes on the electrode surface are suppressed [3Si2/graphene has the largest Warburg and charge-transfer resistances. NiOOH has excellent conductivity and prevents insulator production on the electrode surface, which considerably reduces difficulties in transporting charges. In the low-frequency region, the slope of the straight line indicates the difficulty of ion diffusion. The closer the angle between the line and the x-axis is to 90°, the higher the transmission efficiency of surface ions. The angle of the NiOOH/Graphene electrode, Ni3Si2/Graphene electrode, and Ni3Si2/NiOOH/Graphene electrode are 83.48°, 60.53°, and 79.70°. Overall, Ni3Si2/NiOOH/graphene has faster kinetics, higher conductivity, and a lower ion diffusion resistance during the charge–discharge process.The Nyquist plots of Ni3Si2/NiOOH/graphene was chosen to assemble symmetrical all-solid-state SCs and explore their energy storage performances. Figure −1), 126.3, 71.4, and 58.5 C g−1 at 0.3, 0.6, 1.2, and 3 mA cm−2, respectively. Figure −1 at 750 W kg−1, and the maximal power density is 7500 W kg−1 at 8.13 Wh kg−1. Compared with previous reports [3Si2/NiOOH/graphene all-solid-state SC exhibits higher energy and power densities. Therefore, the Ni3Si2/NiOOH/graphene all-solid-state SC can store more energy per unit weight and output a larger current density. Figure −2, 90.7% of the capacitance is maintained after 6000 cycles. From Fig. 3Si2 structure has not changed significantly, it demonstrates the durability of the Ni3Si2/NiOOH/graphene nanostructure. But a thin film is formed on the surface of the electrode to wrap the entire electrode. Figure 3Si2/NiOOH/graphene supercapacitors in series and charge the supercapacitor system to 2 V. When the voltage across the system reaches 2 V, disconnect the charging system and drive the LED light. In addition, Ni3Si2/NiOOH/graphene demonstrates superior specific capacitance by comparison with other materials . The all-solid-state SCs based on Ni3Si2/NiOOH/graphene nanostructures exhibit outstanding supercapacitor performance, exhibiting an extremely high-energy density (25.9 Wh kg−1 at 750 W kg−1). Even after 6000 cycles at 0.6 mA cm−2, only 10% of the capacitance is lost. This impressive electrochemical behavior indicates that creeper-like Ni3Si2/NiOOH/graphene nanostructures have great potential in the energy storage field.In summary, we successfully fabricated novel creeper-like NiSupplementary material 1 (PDF 629 kb)Below is the link to the electronic supplementary material.


The main findings of our study are determined differences in the ratio of pressure distribution on the inside and the outside foot and differences in kinematic parameters of the outside leg between elements. The mentioned analysis can provide an objective insight into the complexity of each element and provide guidelines for teaching process of those elements. This study determined the reasons for higher complexity of ST compared to PT based on the objective evaluation of biomechanical factors.There are numerous programs worldwide adapted for alpine ski beginners and they all share the same primary goal—inclusion of skiing beginners in alpine ski schools. The final elements of ski school taught in the parallel skiing technique are parallel turn and short turn. Synchronized analysis of kinetic and kinematic parameters of the parallel turn (PT) and short turn (ST) was conducted to determine the main biomechanical differences from a standpoint of foot pressure and lower limb angles. Both elements were performed by nine male ski instructors . Kinetic and kinematic analysis was conducted on 180 turns, 90 for each element. Differences in kinetic and kinematic parameters between parallel and short turns were tested by a paired  Alpine skiing is one of the most popular winter recreational activities . The aimEach ski school program is based on general principles of learning certain motor skills. Considering that skiing is a specific activity which consists of unnatural and uncommon movements for the human body, the principle of gradual learning is crucial. Ski elements are taught starting with simple ones, executed under slow speeds, and then progressing gradually towards more complex elements, which are executed under higher speeds ,7. Once The main unit which is continuously executed while skiing is the ski turn. According to authors who studied alpine skiing, it can be divided in two or three distinct phases ,9,10. StThe final elements of ski school taught in the parallel skiing technique are the parallel turn (PT) and short turn (ST). These elements are also used the most by recreational skiers while conquering the ski slope. Furthermore, their biomechanical characteristics are similar ,14. WhilAlthough numerous descriptions of the alpine skiing technique have been published, relatively little is yet known about the biomechanical factors that influence competitive performance . The numKinematic and kinetic analysis can provide a clear insight in the complexity of each movement while performing a ski turn, and it also allows comparisons between different types of turns ,16,17. BSki schools and ski coaches give their students and athletes feedback about their skiing performance, mainly based on subjective assessments. The Xsens system and pressure insoles can precisely determine biomechanical factors that influence the performance of each ski turn. They could therefore provide a better understanding of ski elements and consequently make the ski school teaching process and the development of young skiers more efficient. For that reason, synchronized analysis of kinetic and kinematic parameters of ST and PT was conducted to determine the main biomechanical differences from a standpoint of foot pressure and lower limbs angles. This analysis can provide an objective insight into the complexity of each element and offer some guidelines for the teaching process. Also, the results can help to clarify whether the usual methodical order of teaching the ST after PT is justified. We hypothesized that the ST is more complex in terms of the technique used, which is manifested in higher foot pressure and a different ratio of pressure distribution regarding the outside and inside foot. Also, regardless of their similarities in specific movements, we assumed there would be differences in kinematic parameters of lower limbs during the performance of ST and PT. Participants: The sample consisted of nine male ski instructors . Participants did not have any prior injuries that could affect skiing techniques or kinetic and kinematic variables in both ski elements. All participants were provided with a detailed explanation of the study procedures and they gave their written informed consent prior to the measuring procedure. The Faculty of Kinesiology, University of Zagreb (Croatia) Ethics Committee approved the study, which was performed following the ethical standards of the Declaration of Helsinki. Variables: Analysis of kinetic and kinematic parameters was conducted on two elements of parallel alpine ski school (PT and ST). A total of 180 turns were analyzed (90 in each element). The variable sample included 10 variables in total. The following kinetic variables were measured: maximum force of the right foot in the left turn (Max_F_R_LT); maximum force of the left foot in the left turn (Max_F_L_LT); maximum force of the left foot in the right turn (Max_F_L_RT); maximum force of the right foot in the right turn (Max_F_R_RT). All results are shown in newtons (N). The following kinematic variables were obtained (180° = knee and hip fully extended): angle of the right hip flexion in the left turn (Hip_R_LT); angle of the right knee flexion in the left turn (Knee_R_LT); angle of the left knee flexion in the left turn (Knee_L_LT); angle of the left hip flexion in the right turn (Hip_L_RT); angle of the left knee flexion in the right turn (Knee_L_RT); angle of the right knee flexion in the right turn (Knee_R_RT). All results are shown in degrees (°). All data were obtained in the final phase of each turn in both elements, precisely in the moment when skiers’ center of mass was at the lowest point and just before releasing the pressure on the outside ski a,b.To measure the kinetic variables, insoles designed for pressure detection  were used. Insoles are thin and light (2 mm), so they have a minimal influence on a skier’s performance during testing, which is especially important during more dynamic skiing, i.e., performance of advanced elements of ski techniques. For the purposes of this study, the sampling rate was set at 100 Hz. Data were derived from the corresponding Novel software  A previous study has confirmed the reliability and validity of Novel pressure insoles for analyzing foot pressure in alpine skiing ,27. Kinematic parameters were measured by a Xsens MVN Link inertial suit system. The system consists of 17 three-dimensional accelerometers/gyroscopes/magnetometers, battery and it was set at a 240 Hz output rate. Data were derived from the corresponding MVN BIOMECH software . Previous studies have confirmed the reliability and validity of the Xsens kinematic suit for analyzing kinematic parameters (joint angles) in alpine skiing ,20,21.Protocol of investigation: All instructors underwent the same protocol: measuring of anthropometric characteristics, adjusting the Xsens suit, adjusting pressure insoles inside the ski boots, a free skiing warm up run, a trial run in corridor for PT, measuring the performance of PT, a trial run in a corridor for ST and measuring the performance of ST.Anthropometric characteristics were used for calibration of the Xsens system. It was used according to the standard of procedure advised by the manufacturer . Standard calibration of pressure insoles was performed according to manufacturers’ advice . In order to synchronize both kinetic and kinematic systems, all turns were recorded with a video camera (Panasonic GH 5). For the purpose of synchronization, participants were asked to alternately lift their skis two times off the snow surface just before starting their descent. That was the starting moment when the time lapse of both systems was aligned.Overall testing was conducted for two days (four instructors on the first day and five on the following day). The study was performed in the morning hours to secure better snow conditions. The average incline of the slope was 20°. Participants had identical skiing equipment  during demonstration of both elements of ski technique. Both ski elements were performed on the selected part of the terrain, taking into consideration the characteristics of specific elements, in previously defined corridor of 15 m wide in the case of PT and 3 m wide in the case of ST . Particit-test was used. The results were considered significant when p < 0.05. With the use of the G*power program, the sample size (number of turns) was calculated (n = 90) that was needed for a measurement procedure with statistical significance of p ˂ 0.05; statistical power 0.8; effect size 0.3 and 2 groups.Statistical analysis: For the statistical analysis, program Statistica version 13.5.0.17  was used. Basic descriptive parameters were calculated for all measured variables. The normality of the data distribution was tested by the Kolmogorov–Smirnov test. For the detection of differences between the elements, a paired t-test are presented in Basic descriptive parameters of each tested variable along with results of paired p = 0.000; p = 0.000). Pressure force values of the outside foot in ST are higher than in PT . The force on the outside foot of ST represents 1.45 of mean body weight (MBW) of tested participants while the force of PT is 1.06 MBW. The force of the inside foot in the left turn was also higher while performing ST compared to PT . In relation to body weight, the measured force in ST was 0.92 MBW was 0.33 MBW in PT. p = 0.000, p = 0.000). The pressure force values of the outside foot in ST are higher than in PT . In relation to body weight, the measured force in ST was 1.37 MBW and was 1.10 MBW in PT. Furthermore, in ST the measured force of the inside foot was higher than in PT . In relation to body weight, the measured force in ST was 0.99 MBW and was 0.28 MBW in PT. In the right turn, a significant difference between the two observed elements was also determined in maximal force pressure of the outside and the inside foot (p = 0.002) in the left turn and in the left knee flexion angle (p = 0.036) in the right turn. At the end of each turn, the knee was more flexed i.e., the skier was in a lower position while performing the ST element . Significant differences regarding kinematic parameters between the two observed elements were found in the right knee flexion angle . Mean values of maximum pressure were higher in ST than in PT, in both feet, while performing elements on both the right and the left side. The ratio of foot pressure between the inside and the outside foot differed in the two observed elements. Foot pressure, although mainly on the outside foot, was significantly higher on the inside foot in ST when comparing the two elements . Higher foot pressure forces of the inside foot in ST could be explained by a higher complexity of the ski element. ST is executed in a more “choppy” fashion and, as was mentioned previously, it is commonly referred to as a short unfinished PT. Therefore, each phase of the turn and consequently the whole turn is performed in a shorter time interval. Each specific movement is executed faster and is performed automatically without preparing for each phase. Body weight is transferred faster from one to another outside ski. During that movement, a skier uses GRF in order to facilitate and speed up the transfer of the pressure from the outside leg to the new outside leg in the following turn. To ease the transfer movement and make it more efficient, the skier must use the inside foot, which will help him to master generated forces. Furthermore, at the end of the turn, the skier cannot control the speed by executing an uphill turn since the turn is unfinished by definition. High values of GRF detected at the end of the ST in this research are just another factor influencing the complexity of speed control. The steepness of the slopes increases the danger of injuries caused by a fall. Collision among skiers is dangerous, especially on steeper slopes where it is harder to stop the sliding after a fall. Therefore, ST is usually executed on the steep slopes by experienced skiers who mastered the speed control at the end of the turn. By using a narrow corridor, a skier minimizes the risk of collision with other skiers. On the other hand, when performing PT, the duration of the turn is longer and there is more time for adjusting movements in each phase of the turn. Also, a skier has more time to apply pressure on the ski surface at the right moment [There is a statistically significant difference between ST and PT in foot pressure forces, both on the outside and the inside foot (t moment . Generatp < 0.05), which is in accordance with data obtained in our research. The authors concluded the main reason for this difference was the lesser time in which the ST must be completed, without skidding which is manifested by an increase of GRF. The increase of GRF is also achieved by a higher edging angle, especially in the last phase of the turn. They suggested that while acquiring ST, the last phase of the turn should be short with a fast transfer of body mass to the other outside ski. While performing PT, the skier learns how to control the center of mass, pressure distribution and edging angle. After mastering the above mentioned techniques, the skier can achieve a high edging angle and utilize a high GRF to transfer the pressure to the new outside foot.Kim and Kim  comparedForce distribution analysis was conducted on elite ski instructors while performing slalom (SL) and giant slalom (GS) turn in a study of Lamontagne . His finIn a research conducted by Falda–Buscaiot et al. , the ratp = 0.002, p = 0.036). In ST it is very important to utilize the ground reaction force at the end of the turn in order to be faster in transition. Consequently, the skier must be in a lower position, i.e., his knee angle of the outside leg is smaller . Kröll et al. [Kinematic analysis showed significant differences between turns in knee angle values of the outside leg (l et al.  investigIn the previously cited study conducted by Kroll et al. , during Most of the kinetics and kinematics research addressed the issues of force application and changes in joint angles during dynamic performances of racers ,29,30,32Information about the timing of specific body movements which ensure optimal control of direction and speed could be crucial for accomplishing the aim of each alpine ski school—to enable skiers to be independent in mastering complex skiing elements. This research determined the reasons for higher complexity of ST compared to PT based on the objective evaluation of biomechanical factors that influence the performance of each element. Therefore, we confirmed that current methodical order of teaching ST after PT is justified. Based on our research, the turns performed in a narrow corridor are more complex due to their pressure distribution and lower body joint flexion, which is probably caused by a greater separation of movement in upper and lower body. Ski instructors and coaches should follow the methodical process from the beginning of teaching. All technical elements should be demonstrated and taught in a wide corridor with longer duration of each turn phase. This way, the students and athletes will have the necessary time to process and perform all the movements. Future studies should be focused on observing biomechanical factors of all the elements performed in narrow and wide corridors. Only then would it be possible to make a conclusion about the reasons beneath the complexity of performing a turn in a narrow corridor.The presented study is focused on kinematic and kinetic analysis of only two elements of alpine ski school. To make a conclusion about the complexity of elements and teaching methodology, it would be necessary to conduct measurements of each element included in alpine ski school program and every methodical exercise for teaching those elements. This would give ski instructors and coaches much more assurance when deciding upon the choice and the order of methodical exercises to use in the most efficient way to upgrade the teaching process of ski elements. Furthermore, it would be useful to determine pressure distribution on different areas of foot during performing different phases of the turn.The results of the conducted synchronized analysis of ski elements determined different ratio of pressure distribution between the elements. The pressure on the inside leg is relatively higher in ST compared to PT. Kinematic analysis pointed out differences in the knee angle of the outside leg, which has a role of controlling the speed and direction during descent. ST is more complex and skiers can only safely perform ST after mastering the optimal and balanced position with pressure dominantly on the outside ski recreational level alpine.Similar findings were determined in various alpine skiing studies focused on kinetic and kinematic analysis. Differences between those studies and the present one are participants and the type of analyzed turns. Although there are similarities between SL and GS and some elements of alpine ski school, it is important to be cautious when making conclusions about recreational skiing based on ski racers and their turns. Studies focused on alpine ski schools are necessary to determine crucial biomechanical factors influencing the performance of each element. It is important that ski instructors have that information because it can serve as a guideline for adapting their teaching process and make it more efficient, which will consequently reduce injuries.