Physical fitness characteristics of elite freestyle skiing aerials athletes.

OBJECTIVE: To analyze the physical fitness characteristics of elite freestyle skiing aerials athletes, thereby enhancing the understanding of exercise physiologists, sports scientists, and coaches regarding the demands in this discipline. METHODS: After health screenings, 29 athletes from the Chinese National Freestyle Skiing Aerials Team were divided into elite and general groups, including males and females. Physical fitness indexes were determined through literature reviews, expert interviews, and the Delphi method, followed by physical fitness tests assessing body morphology, physiological function, and physical quality. Data normality was verified using the Shapiro-Wilk test. Differences between the two groups were then evaluated using independent sample t-tests or Mann-Whitney U tests, after which effect sizes were calculated to assess the magnitude of the differences. RESULTS: Significant body morphology differences were noted between elite and general groups in fat-free body weight, leg, and waist circumferences (P < 0.05). Male athletes in the elite group exhibited a significantly lower percentage of body fat (P < 0.05), whereas the reduction in body fat percentage among female elite athletes was not statistically significant. In terms of physiological function assessment, elite athletes demonstrated superior performance in both maximum anaerobic capacity and relative maximum anaerobic capacity compared to their counterparts in the general group (P < 0.05). Notably, the difference in maximum anaerobic capacity was highly significant among male athletes (P < 0.01), and the relative maximum anaerobic capacity among female athletes was also markedly significant (P < 0.01). Regarding physical quality indexes, elite athletes outperformed those in the general group in all aspects except for the quick v-up and 12-minute run tests (P < 0.05 or P<0.01). CONCLUSION: Elite athletes exhibit superior physical fitness characteristics compared to general athletes, attributable to differences in age, years of training, and their participation in ongoing specialized physical training within structured, cyclical programs. Specifically, elite athletes demonstrated higher fat-free body weight, larger waist and leg circumferences in terms of body morphology. Particularly, male athletes showed a trend towards lower body fat percentage. Physiologically, they exhibited stronger anaerobic metabolism capabilities. In terms of physical quality, elite athletes displayed superior limb strength, lower limb explosive power, and specialized core strength, along with better speed, agility, and overall coordination.

NIR-II Excitable Water-Dispersible Two-Dimensional Conjugated Polymer Nanoplates for In Vivo Two-Photon Luminescence Bioimaging.

While two-dimensional conjugated polymers (2DCPs) have shown great promise in two-photon luminescence (TPL) bioimaging, 2DCP-based TPL imaging agents that can be excited in the second near-infrared window (NIR-II) have rarely been reported so far. Herein, we report two 2DCPs including 2DCP1 and 2DCP2, with octupolar olefin-linked structures for NIR-II-excited bioimaging. The 2DCPs are customized with the fully conjugated donor-acceptor (D-A) linkage and aggregation-induced emission (AIE) active building blocks, leading to good two-photon absorption into the NIR-II window with a 2PACS of ∼64.0 GM per choromophore for both 2DCPs. Moreover, 2DCP1 powders can be exfoliated into water-dispersible nanoplates with a Pluronic F-127 surfactant-assisted temperature-swing method, accompanied by both a drastic reduction of 2PACS throughout the range of 780-1080 nm and a sharp increase of photoluminescence quantum yield to 33.3%. The 2DCP1 nanoplates are subsequently proven to be capable of assisting in visualizing mouse brain vasculatures with a penetration depth of 421 µm and good contrast in vivo, albeit that only 19% of previous 2PACS at 1040 nm is preserved. This work not only provides important insights on how to construct NIR-II excitable 2DCPs for TPL bioimaging but also how to investigate the exfoliation-photophysical property correlation of 2DCPs, which should aid in future research on developing highly efficient TPL bioimaging agents.

Construction of a physical fitness evaluation index system and model for high-level freestyle skiing aerials athletes in China.

OBJECTIVE: This study aims to enhance the competitive level of Chinese freestyle skiing aerials athletes by developing a specialized physical fitness evaluation index system and model tailored for high-level Chinese athletes. This system intends to provide theoretical references and training monitoring schemes in preparation for the 25th Milan Winter Olympics. METHODS: A study was conducted on 29 high-level Chinese freestyle skiing aerials athletes. Physical fitness test indexes were selected using a literature review, expert interviews, and questionnaire surveys, and athletes were tested. Athletes were ensured to be in optimal physical condition before testing. Based on the test results, the representative indexes of the evaluation system are finally determined by combining R-type clustering analysis, multiple linear regression analysis. Determine index weights through weight questionnaires and normalization, and develop evaluation standards through methods such as percentile counting and weighted scoring. RESULTS: Physical fitness evaluation system for Chinese freestyle skiing aerialists includes three aspects: evaluation index, index weight, and evaluation standard. The evaluation indexes include 3 first-level, 11 second-level, and 11 third-level indexes of body form, physiological function, and physical quality. In the evaluation weight, physical quality is ranked first, and physiological function and body form rank second and third, respectively. The evaluation standard consists of a scoring evaluation standard and a rating evaluation standard. Based on the index system, this study constructs the general and ideal physical fitness model of China's high-level freestyle aerials athletes. CONCLUSION: The constructed physical fitness evaluation system effectively represents physical fitness development status of high-level freestyle skiing aerials athletes, providing a basis for creating personalized training plans. The established model serves as a reference for athletes' physical fitness development objectives.

MOF-Transformed In2O3-x@C Nanocorn Electrocatalyst for Efficient CO2 Reduction to HCOOH.

For electrochemical CO2 reduction to HCOOH, an ongoing challenge is to design energy efficient electrocatalysts that can deliver a high HCOOH current density (JHCOOH) at a low overpotential. Indium oxide is good HCOOH production catalyst but with low conductivity. In this work, we report a unique corn design of In2O3-x@C nanocatalyst, wherein In2O3-x nanocube as the fine grains dispersed uniformly on the carbon nanorod cob, resulting in the enhanced conductivity. Excellent performance is achieved with 84% Faradaic efficiency (FE) and 11 mA cm-2 JHCOOH at a low potential of - 0.4 V versus RHE. At the current density of 100 mA cm-2, the applied potential remained stable for more than 120 h with the FE above 90%. Density functional theory calculations reveal that the abundant oxygen vacancy in In2O3-x has exposed more In3+ sites with activated electroactivity, which facilitates the formation of HCOO* intermediate. Operando X-ray absorption spectroscopy also confirms In3+ as the active site and the key intermediate of HCOO* during the process of CO2 reduction to HCOOH.

Surfactant-Modulated a Highly Sensitive Fluorescent Probe of Fully Conjugated Covalent Organic Nanosheets for Detecting Copper Ions in Aqueous Solution.

Efficient detection of aqueous copper ions is of high significance for environmental and human health, since copper is involved in potent redox activity in physiological and pathological processes. Covalent organic frameworks (COFs) have shown advantages in efficient capturing and detecting of copper ions due to their large surface area, robust chemical stability, and high sensitivity, but most of them are hydrophobic, leading to the limitation in sensing copper ions in aqueous media. Herein, the design and synthesis of an sp2 -carbon conjugated COF (sp2 -TPE-COF) are reported with surfactant-assisted water dispersion for detecting traces of copper ions based on the photo-induced electron transfer (PET) mechanism. Importantly, the olefin-linked conjugated backbone of sp2 -TPE-COF works as a signal amplified transducer for metal ion sensing. Notably, it is found that a surfactant-assisted strategy can greatly enhance COF's dispersion in aqueous solution and finely modulate their sensitivity with a significantly improved KSV to 15.15 × 104 m-1 in SDBS (sodium dodecyl benzene sulfonate) solution, the value of which is larger than that of a majority of COF/MOF based sensors for copper ions. This research demonstrates the promise of surfactant modulated fully π-conjugated COFs for sensing applications.

A mild molecular fusion route for the synthesis of polyhedral carbon nano-onions with high graphitization.

Polyhedral carbon nano-onions (CNOs) compared with traditional quasi-spherical CNOs are more stable and have less defects, which will greatly broaden their potential applications. However, there still lacks of a suitable synthetic method. Here, we developed a simple molecular fusion route and templet growth method by which polyhedral CNOs can be successfully synthesized. Characterization of the polyhedral CNOs by transmission electron microscopy, x-ray diffraction and Raman spectroscopy indicates that they have an ultra-high degree of graphitization and a large cavity diameter of about 10 nm, which results in their low density of 1.42 g cm-3. In addition, the deeper reaction mechanism of polyhedral CNOs growth was also elucidated. It was found that the channel structure and the absorption of the templet play the crucial role during the formation of polyhedral CNOs.

Preparation and Characterization of DOPO-Functionalized MWCNT and Its High Flame-Retardant Performance in Epoxy Nanocomposites.

In this work, functionalized multi-walled carbon nanotubes (MWCNT) were synthesized by the reaction between acylated MWCNT and 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (ODOPB). The obtained MWCNT-ODOPB was well dispersed into epoxy resins together with aluminum diethylphosphinate (AlPi) to form flame-retardant nanocomposites. The epoxy resin nanocomposite with phosphorus content of 1.00 wt % met UL 94 V-0 rating, exhibited LOI value of 39.5, and had a higher Tg compared to neat epoxy resin, which indicates its excellent flame retardant performance. These experimental results indicated that MWCNT-ODOPB was a compatible and efficient flame retardant for epoxy resins. Moreover, cone calorimeter analysis showed that the peak heat release rate (pHRR), total heat release (THR) values, and CO2 production profiles of the composites decreased with an increase in the additional amount of phosphorus.

Compensating film stress in thin silicon substrates using ion implantation.

Future space telescopes, especially X-ray telescopes, will require thin mirrors to achieve high optical throughput. Thin mirrors are more difficult to fabricate than thick mirrors, but recent advances have made accurate fabrication of thin mirrors possible. However, mirrors must have a reflective coating, which typically has non-repeatable and non-uniform intrinsic stress that deforms a thin mirror. Reducing coating stress by controlling deposition parameters typically reduces reflectivity. Non-uniform integrated stress compensation (NISC) methods, in which spatially controlled stress is applied to the mirror substrate backside to balance the frontside coating stress, decouple the film stress from the reflectivity. Ion implantation is one NISC method, where high-energy ions are implanted into a glass or silicon substrate to generate stress near the substrate surface. In this paper, we demonstrate the use of ion implantation for stress compensation of 30 nm thick chromium films applied to the front of five silicon wafers. The reflective films have mean integrated stress between -8 and -35 N/m, which cause deformations between 400 and 1600 nm RMS. We demonstrate that these wafers can be restored to the pre-coating shape to within 60 nm RMS, in most cases within 1/20th of the coating deformation.

Suppression of reflected side lobes in narrow-band X-ray multilayer coatings.

We present an analytical method for the design of narrow-band X-ray multilayer coatings having greatly reduced reflected side-lobe intensity, for the realization of X-ray mirrors that have improved spectral purity. The method uses a specific variation of the individual layer thicknesses as a function of depth in the multilayer stack, derived from Laplace transform analysis of the multilayer's reflectance profile. The design process and mathematical foundations are outlined. Pt/C multilayers with 5 nm d-spacing for hard X-rays are designed, fabricated and measured to demonstrate the validity and effectiveness of the method are presented. As an extrapolation, three additional side lobe suppressed multilayers for soft X-rays and EUVs are also designed and investigated: 1) Cr/Sc multilayer for soft X-rays (4.96 nm wavelength) at high grazing angle (30°), 2) Mo/Si multilayer for EUV (13.5 nm wavelength) at normal incidence angle and 3) SiC/Mg multilayer for EUV (30.4 nm wavelength) at normal incidence angle. The calculated reflectances demonstrate that the presented method is robust for the energy range from X-rays to EUVs.

Generation of Ultrafine Droplets in Femtoliter Scale from a Large Needle with Diameter of 200 Microns.

Ultrafine droplets play important roles in many fields. Here, we prepare ultrafine droplets with volumes in femtoliter scale by applying an electrostatic field between a needle and substrate. The diameter of liquid is reduced significantly to about 1/50 that of the needle tip. By using some solvents consisting of small molecules, ultrafine droplets eject from the needle tip. The volume of the ultrafine droplets depend on the strength of the electrostatic field and properties of the liquid. Ultrafine droplets containing perovskite quantum dots are also ejected on the substrate by using this jetting method. The ultrafine droplets have great potentials in carrying tiny amount of quantum dots and even molecules for various applications.

Thermal oxide patterning method for compensating coating stress in silicon substrates.

We introduce a novel method for correcting distortion in thin silicon substrates caused by coating stress. Thin substrates, such as lightweight mirrors for x-ray or optical imaging, and semiconductor wafers or flat panel substrates, are easily distorted by stress in thin film coatings. We report a new method for correcting stress-induced distortion in flat silicon substrates which utilizes a micro-patterned silicon oxide layer on the back side of the substrate. Due to the excellent lithographic precision of the patterning process, we demonstrate stress compensation control to a precision of ~0.2%. The proposed process is simple and inexpensive due to the relatively large pattern features on the photomask. The correction process has been tested on flat silicon wafers that were distorted by 30 nm-thick compressively-stressed coatings of chromium, achieving RMS surface height and slope error reductions of a factor of 68 and 50, respectively.

Small Titanium-Based MOFs Prepared with the Introduction of Tetraethyl Orthosilicate and Their Potential for Use in Drug Delivery.

Metal-organic frameworks (MOFs) have attracted much attention in the areas of biomedicine and medicine owing to their versatile porous structure. However, the oversize and high cellular toxicity of some metal-based MOF particles have hindered their development. Therefore, a series of small Ti-based MOFs are prepared with the introduction of tetraethyl orthosilicate (TEOS) into the reaction system. Compared with the Ti-based MOFs prepared by traditional methods, the size of the Ti-based MOFs prepared with this method is decreased by 42.78%. Meanwhile, the good biocompatibility of the prepared Ti-based MOF particles toward the L929 cell lines is proven using CCK-8 assays. Furthermore, the controlled release property of the Ti-based MOFs is evaluated by using ibuprofen (IBU) as a model drug. The amount of drug loaded in the samples is shown to be approximately 10%, and approximately 95% of the IBU is released from the MOFs after exposure to PBS for 24 h. We conclude that the size-decreased Ti-based MOFs prepared with the introduction of TEOS into the reaction systems are potential drug carriers in terms of their good biocompatibility and effective performance in the controlled release of a drug.

Carrier-Free Microspheres of an Anti-Cancer Drug Synthesized via a Sodium Catalyst for Controlled-Release Drug Delivery.

There are several challenges involved in the development of effective anti-cancer drugs, including accurate drug delivery without toxic side effects. Possible systemic toxicity and the rapid biodegradation of drug carriers are potential risks in the use of carriers for drug-delivery formulations. Therefore, the carrier-free drug delivery of an anti-cancer drug is desirable. Herein, 4-amino-2-benzyl-6-methylpyrimidine (ABMP) was synthesized via a new method using a sodium catalyst, and proved to be effective in inducing breast cancer cell (MDA-MB-231) apoptosis. Moreover, the transparent amorphous state solid of ABMP was demonstrated to have a slow-release property in phosphate buffer solution (PBS). Microspheres of ABMP were prepared with diameters in the range of 5-15 µm. The slow-release property of the ABMP microspheres indicated their potential use for controlled-release drug delivery. We believe that microspheres of ABMP have potential as a new kind of carrier-free anti-cancer drug delivery system.

Elucidating the Key Role of a Lewis Base Solvent in the Formation of Perovskite Films Fabricated from the Lewis Adduct Approach.

High-quality perovskite films can be fabricated from Lewis acid-base adducts through molecule exchange. Substantial work is needed to fully understand the formation mechanism of the perovskite films, which helps to further improve their quality. Here, we study the formation of CH3NH3PbI3 perovskite films by introducing some dimethylacetamide into the PbI2/N,N-dimethylformamide solution. We reveal that there are three key processes during the formation of perovskite films through the Lewis acid-base adduct approach: molecule intercalation of solvent into the PbI2 lattice, molecule exchange between the solvent and CH3NH3I, and dissolution-recrystallization of the perovskite grains during annealing. The Lewis base solvents play multiple functions in the above processes. The properties of the solvent, including Lewis basicity and boiling point, play key roles in forming smooth perovskite films with large grains. We also provide some rules for choosing Lewis base additives to prepare high-quality perovskite films through the Lewis adduct approach.

Amorphous In-Ga-Zn-O Powder with High Gas Selectivity towards Wide Range Concentration of C2H5OH.

Amorphous indium gallium zinc oxide (a-IGZO) powder was prepared by typical solution-based process and post-annealing process. The sample was used as sensor for detecting C2H5OH, H2, and CO. Gas-sensing performance was found to be highly sensitive to C2H5OH gas in a wide range of concentration (0.5-1250 ppm) with the response of 2.0 towards 0.5 ppm and 89.2 towards 1250 ppm. Obvious difference of response towards C2H5OH, H2, and CO was found that the response e.g., was 33.20, 6.64, and 2.84 respectively at the concentration of 200 ppm. The response time and recovery time of was 32 s and 14 s respectively towards 200 ppm concentration of C2H5OH gas under heating voltage of 6.5 V.

Dendrite-Free, High-Rate, Long-Life Lithium Metal Batteries with a 3D Cross-Linked Network Polymer Electrolyte.

A 3D network gel polymer electrolyte (3D-GPE) is designed for lithium metal batteries and prepared by an initiator-free one-pot ring-opening polymerization technique. This 3D-GPE exhibits an unprecedented combination of mechanical strength, ionic conductivity, and more importantly, effective suppression of Li dendrite growth. The produced lithium-based battery presents long life, high rate, and excellent safety.

Facile synthesis of a water-soluble fluorescence sensor for Al3+ in aqueous solution and on paper substrate.

In this study, a facile water-soluble fluorescence sensor 2-((2-hydroxybenzylidene)-amino)-2-(hydroxymethyl)propane-1,3-diol (ST) was synthesized via one-step reaction, and its fluorescence sensing performance for Al3+ both in aqueous solution and on paper substrate was evaluated. The results showed that ST exhibited an specific fluorescence "turn-on" response to Al3+ over other cations in aqueous solution as well as on the test paper. The limit of detection was found to be 3.2×10-7M, which revealed that the obtained Schiff-base based fluorescence chemosensor ST possessed a great potential for the rapid, quantitative and qualitative detection of Al3+.

Enhanced performance of perovskite solar cells by modulating the Lewis acid-base reaction.

The Lewis acid-base reaction between PbI2 and solvent molecules is popular in fabricating PbI2 films by a two-step method for making perovskite solar cells. Here, we control the microstructure of PbI2 films through modulating the Lewis acid-base reaction by adding a small amount of N-methyl pyrrolidone into PbI2/DMF solution. PbI2 films with excellent crystallinity and full coverage are fabricated by spin-coating the mixed solution on the substrate, which leads to high quality perovskite layers with low recombination rate and high efficiency for carrier transfer. As a result, the power conversion efficiency of the best perovskite solar cells increases from 13.3% to 17.5%.

Stress manipulated coating for fabricating lightweight X-ray telescope mirrors.

In this paper wepresent a method to correct the surface profile of an X-ray mirror by using a stress manipulated coating on the back side of mirror shells. The ability to fabricate a thin walled mirror by some replication process is required if future affordable X-ray space missions are to have ~30 times the effective area of the current best X-ray observatory, i.e., the Chandra X-ray Observatory (CXO). Thus, some process is necessary for using replicated X-ray optics to make the next generation X-ray observatory. However, although the surface roughness of sub-100 µm length scales can be replicated, no known replication technique can make 1 arc-second or better CXO-like optics. Yet, because the images produced by the CXO are so exquisite, many X-ray astronomers are not willing to settle for less in the future. Therefore, a post replication technique must be developed to make future major X-ray astronomy missions possible. In this paper, we describe a technique based on DC magnetron sputtering. For figure correction, we apply a controlled bias voltage on the surface during the sputtering. We show that we can produce, in 1-D, shape changes large enough (1 µm over 10 mm) to correct the typical figure errors in replicated optics. We demonstrate reproducibility on an order of 0.6%, and stability over weeks on a scale of less than 1 µm over 10 mm. For these tests, we used 200 µm thick pieces of D263 Schott glass, about 5 mm x 20 mm. In addition to the basic concept of controlling the stress with the coating, we describe a new optimization software design to calculate the stress distribution for a desired surface profile. We show that the combination of the stress optimization software coupled with the coating process, can reduce the slope error of a 5 mm x 20 mm glass sample by a factor of ten.

Synthesis of morphology-controlled ZnO microstructures via a microwave-assisted hydrothermal method and their gas-sensing property.

Controllable ZnO architectures with flower-like and rod-like morphologies were synthesized via a microwave-assisted hydrothermal method. By adjusting the concentration of Zn(2+) in the aqueous precursors, different morphologies of ZnO microstructures were obtained. The size of ZnO was uniform after ultrasonic treatment. The growth process of ZnO in solution was studied by monitoring the intermediate products, which were extracted at different stages of the reactions: (i) precursor preparation, (ii) microwave irradiation heating, (iii) natural cooling. Studies of the SEM images and XRD data revealed that the formation of ZnO occurred via in situ assembly or dissolution-reprecipitation of zinc hydroxide complexes. The morphology-dependent ethanol sensing performance was observed; the seven-spine ZnO structures exhibit the highest activity.