Diaphragm Function in Elite Weightlifters With and Without Chronic Low Back Pain and its Impacts on Sports Performance.

ABSTRACT: Zhou, EFM, Wong, AYL, Peng, J, Lin, G, Wen, T, Fang, J, Zhou, C, and Fu, SN. Diaphragm function in elite weightlifters with and without chronic low back pain and its impacts on sports performance. J Strength Cond Res XX(X): 000-000, 2024-The aim of this study was to compare diaphragm function between elite weightlifters with and without chronic low back pain (LBP) and to explore the associations between diaphragm function and sports performance. Forty-nine elite weightlifters aged 16-26 years were recruited, including 29 women (16-25 years, mean ± SD = 19.93 ± 2.70 years) and 20 men (16-26 years, mean ± SD = 20.95 ± 2.68 years). Of these, 23 subjects had chronic LBP. Diaphragm thickness and excursion were assessed using ultrasonography, and maximal inspiratory pressure (MIP), measured with POWERbreathe KH2, served as indicators of diaphragm contractility and strength, respectively. Sports performance was gauged through maximal snatch and clean and jerk lifts. Group differences and performance correlations were analyzed with consideration for confounders. The significance was set at p ≤ 0.05. Weightlifters with chronic LBP demonstrated significantly lower diaphragmatic contractility: diaphragm thickening fraction (by 21%; mean difference [MD] = 0.09, p = 0.04, Cohen's d = 0.69) and diaphragm excursion (by 18%; MD = 0.99, p < 0.01, Cohen's d = 0.89) compared with non-LBP controls. In addition, MIP was positively related to snatch (r = 0.34, p = 0.02) and clean and jerk (r = 0.43, p < 0.01) lifts. This study revealed that elite weightlifters with chronic LBP exhibit reduced diaphragm contractility, and inspiratory muscle force output (primary diaphragm) was associated with lifting performance. Incorporating diaphragm strengthening into training and rehabilitation might enhance performance and aid in LBP management, offering a dual benefit for athletes.

Semiconductor SERS on Colourful Substrates with Fabry-Pérot Cavities.

Non-metallic materials have emerged as a new family of active substrates for surface-enhanced Raman scattering (SERS), with unique advantages over their metal counterparts. However, owing to their inefficient interaction with the incident wavelength, the Raman enhancement achieved with non-metallic materials is considerably lower with respect to the metallic ones. Herein, we propose colourful semiconductor-based SERS substrates for the first time by utilizing a Fabry-Pérot cavity, which realize a large freedom in manipulating light. Owing to the delicate adjustment of the absorption in terms of both frequency and intensity, resonant absorption can be achieved with a variety of non-metal SERS substrates, with the sensitivity further enhanced by ≈100 times. As a typical example, by introducing a Fabry-Pérot-type substrate fabricated with SiO2 /Si, a rather low detection limit of 10-16  M for the SARS-CoV-2S protein is achieved on SnS2 . This study provides a realistic strategy for increasing SERS sensitivity when semiconductors are employed as SERS substrates.

Efficient NOx Abatement over Alkali-Resistant Catalysts via Constructing Durable Dimeric VOx Species.

The presence of alkali metals in flue gas is still an obstacle to the practical application of catalysts for selective catalytic reduction (SCR) of NOx by NH3. Polymeric vanadyl species play an essential role in ensuring the effective NOx abatement for NH3-SCR. However, polymeric vanadyl would be conventionally deactivated by the poison of alkali metals such as potassium, and it still remains a great challenge to construct robust and stable vanadyl species. Here, it was demonstrated that a more durable dimeric VOx active site could be constructed with the assistance of triethylamine, thereby achieving alkali-resistant NOx abatement. Due to the rational construction of polymerization structures, the obtained TiO2-supported cerium vanadate catalyst featured more stable dimeric VOx species and the active sites could survive even after the poisoning of alkali metal. Moreover, the depolymerization of VOx was suppressed endowing the catalysts with more Brønsted and Lewis acid sites after the poisoning of alkali metal, which ensured the efficient NOx reduction. This work unraveled the effects of alkali metal on the polymerization state of active species and opens up a way to develop low-temperature alkali-resistant catalysts for NOx abatement.

Multiple Stimuli-Responsive Conformational Exchanges of Biphen[3]arene Macrocycle.

Conformational exchanges of synthetic macrocyclic acceptors are rather fast, which is rarely studied in the absence of guests. Here, we report multiple stimuli-responsive conformational exchanges between two preexisting conformations of 2,2',4,4'-tetramethoxyl biphen[3]arene (MeBP3) macrocycle. Structures of these two conformations are both observed in solid state, and characterized by 1H NMR, 13C NMR and 2D NMR in solution. In particular, conformational exchanges can respond to solvents, temperatures, guest binding and acid/base addition. The current system may have a role to play in the construction of molecular switches and other stimuli-responsive systems.

Schiff-base reaction induced selective sensing of trace dopamine based on a Pt41Rh59 alloy/ZIF-90 nanocomposite.

Zeolitic imidazole frameworks (ZIFs) are a new class of functional porous materials with attractive characters, such as gas storage, selective separation, catalysis, and drug delivery. We report herein using nanoscale ZIF-90 crystals with free aldehyde group of imidazole-2-carboxaldehyde (ICA) ligand for the selective electrochemical detection of dopamine. The averaged adsorption enthalpy ΔH (i.e., isosteric heat) of ZIF-90 to dopamine is estimated as 72 kJ mol-1 according to grand canonical Monte Carlo (GCMC) simulation. With further modification of a Pt41Rh59 alloy nanocatalyst, the electrochemical sensing performances towards dopamine are improved. The synergetic effect generated by a Pt41Rh59/ZIF-90 nanocomposite endows it a low detection limit of 1 nM and good specificity. The different anti-interference mechanisms to coexisting redox active species and amino analogues are also included in this work. The strategy demonstrated here may be extended to tune metal nodes as well as ligands of ZIFs crystals and further regulating their functionalities for different target molecules identification.

Efficient Separation of cis- and trans-1,2-Dichloroethene Isomers by Adaptive Biphen[3]arene Crystals.

Reported here is the highly efficient separation of industrially important cis- and trans-1,2-dichloroethene (cis-DCE and trans-DCE) isomers by activated crystalline 2,2',4,4'-tetramethoxyl biphen[3]arene (MeBP3) materials, MeBP3α. MeBP3 can be synthesized in excellent yield (99 %), and a cyclic pentamer is also obtained when using 1,2-dichloroethane as the solvent. The structure of MeBP3 in the CH3 CN@MeBP3 crystal displays a triangle-shape topology, forming 1D channels through window-to-window packing. Desolvated crystalline MeBP3 materials, MeBP3α, preferentially adsorb cis-DCE vapors over its trans isomer. MeBP3α is able to separate cis-DCE from a 50:50 (v/v) cis/trans-isomer mixture, yielding cis-DCE with a purity of 96.4 % in a single adsorption cycle. Single-crystal structures and powder X-ray diffraction patterns indicate that the uptake of cis-DCE triggers a solid-state structural transformation of MeBP3, suggesting the adaptivity of MeBP3α materials during the sorption process. Moreover, the separation can be performed over multiple cycles without loss of separation selectivity and capacity.

A Homochiral {CoΙΙ16 CoΙΙΙ4 } Supertetrahedral T4 Cluster from a Racemic Ligand with Ferromagnetic Behavior and High Photocatalytic Activity.

A homochiral mixed-valence cobalt cluster [CoΙΙ16 CoΙΙΙ4 (µ6 -O)4 (µ3 -OH)12 (S-bme)12 (OAc)6 ]Cl6 ⋅5 CH3 OH⋅18 H2 O (1, Hbme=1H-(benzimidazol-2-yl)ethanol) was synthesized from a racemic ligand and three cobalt salts of CoCl2 ⋅6 H2 O, Co(Ac)2 ⋅4 H2 O and Co(NO3 )2 ⋅6 H2 O in a DMF/MeOH mixed solvent. The enantioselective coordination occurs when a large excess of cobalt ions added in the solution and only the S-configuration of the racemic ligand involved in crystallization. The CD spectra of three crystal samples show identical Cotton signals, indicating the repeatability and the enantiomeric purity of the single crystals. This compound presents a beautiful two-shell Matryoshka-type supertetrahedral T4 cluster constructed by an inner CoΙΙΙ4 O4 cubane and four exterior CoΙΙ4 O4 cubanes bridged by µ6 -O2- and µ3 -OH- ions. This highest nuclear chiral cobalt cluster is the first example of enantiopure cobalt cluster separated from a racemic ligand and is the largest supertetrahedral cobalt cluster up to now. The magnetic studies reveal it behaves as a ferromagnet. Photocatalytic properties of 1 show high catalytic activities for the degradation of the highly toxic triphenyl dye crystal violet (CV) in the presence of H2 O2 under visible light in aqueous solution. The degradation rate almost reach 100 % at 45 min and can maintain 98.54 % after 8 cycles.

Pt35Cu65 nanoarchitecture: a highly durable and effective electrocatalyst towards methanol oxidation.

Aiming at electro-catalytic performance enhancement and reduction of catalyst cost, PtxCu1-x (Pt35Cu65, Pt53Cu47, and Pt68Cu32) nanoarchitecture samples with controllable atomic composition, similar morphology and particle-size have been prepared by using a one-pot chemical route. The as-prepared PtxCu1-x nanoarchitectures are confirmed as consisting of the integration of initial small alloy nanoparticles (NPs), resulting in an interconnected nanoporous structure. The electrochemical experiments indicate that these PtxCu1-x nanocatalysts exhibit atomic composition dependent catalytic activity, although the surfaces of all the catalysts were characterized to be featured with a Pt enrichment structure. With optimal atomic composition, the Pt35Cu65 catalyst possesses enhanced electro-catalytic activities towards methanol oxidation in comparison with other PtxCu1-x samples and pure Pt catalyst with similar morphology. Furthermore, the integrated Pt35Cu65 nanoarchitecture displays good durability during the long term electrochemical scanning through as many as 1500 cycles. The comparable catalytic performance of Pt35Cu65 catalyst could be attributed to the interconnected initial small NPs, formation of open porous structure, durable nanoarchitecture, and synergetic effect of the alloyed atoms. The structural evolution from metastable small alloy NPs to integrated stable nanoarchitectures may provide new opportunities to design and prepare novel composite materials with durable structure and effective catalytic properties.

TEMPO-mediated oxidized winter melon-based carbonaceous aerogel as an ultralight 3D support for enhanced photodegradation of organic pollutants.

Natural biomass based carbonaceous aerogels are becoming promising lightweight, biodegradable matrices to supersede traditional support materials in realizing future sustainable photochemistry and environmental protection. Herein, flower-like BiOBr loaded onto an ultralight TEMPO-mediated oxidized carbonaceous aerogel (BOB@OWMCA) support was successfully prepared using the edible winter melon as source material via a simple solvothermal method. The three-dimensional sponge-like OWMCA with surface functionalization displayed an ultralow density (17.7 mg cm(-3)) and large special surface area (30.6 m(2) g(-1)). The BiOBr was homogeneously anchored on the surface of the hierarchical porous OWMCA and the material exhibited synergetic properties of the BiOBr photocatalyst and OWMCA support to strengthen its photodegradation capacity. The results indicated that the as-prepared BOB@OWMCA composite demonstrated an outstanding adsorption and photodegradation capacity for organic pollutants (rhodamine B) under visible light irradiation. Of importance here, the BOB@OWMCA composite showed a prominent advantage for easy collection and separation from the aqueous system, making it a promising candidate as a robust visible light responsive photocatalyst for a range of applications.

Investigating the metabolism of four sulfonamides in grass carp via HPLC-MS for screening candidate materials of matrix reference material.

An efficient, sensitive, and precise method for investigating the metabolism of four sulfonamides in grass carp has been established using high-performance liquid chromatography-mass spectrometry. By optimizing the experimental conditions, the method achieved a coefficient of determination above 0.999, with detection and quantification limits set at 0.5 µg/kg and 1.0 µg/kg, respectively. Recovery rates were between 92.90 % and 102.84 %, and relative standard deviations ranged from 1.70 % to 9.83 %, enabling the precise detection of these sulfonamides in grass carp tissue. The factors affecting the metabolic rate during the medicated bath process were investigated, and obtained the optimal parameter conditions for screening the candidate materials. The candidate materials screened through this method exhibit good stability when used to prepare matrix standard substances, this work not only provides a scientific basis for screening sulfonamide candidate materials but also offers insights for developing other matrix reference materials.

Density functional theory study of the mechanisms of iron-catalyzed cross-coupling reactions of alkyl grignard reagents.

When compared with the established palladium and nickel catalyst systems, simple iron salts turn out to be highly efficient, cheap, toxicologically benign, and environmentally friendly precatalysts for a host of cross-coupling reactions of alkyl or aryl Grignard reagents. The inorganic Grignard reagent [Fe(MgX)(2)], where X corresponds to Br or I, is a good catalyst for cross-coupling reactions. The present study reports a thorough theoretical analysis of the mechanisms of the [Fe(MgBr)(2)] catalyzed cross-coupling reaction between 4-chlorobenzoic acid methyl ester and n-hexylicmagnesium bromide using density functional theory (DFT) calculations. Our calculations show that the overall catalytic cycle includes three basic steps: oxidation of [Fe(MgBr)(2)] to obtain [Ar-Fe(MgBr)], addition to yield [Ar-(n-hexyl)-Fe(MgBr)(2)], and reductive elimination to return to [Fe(MgBr)(2)]. The energy barrier is lower if n-hexylicmagnesium bromide attacks the intermediate of the oxidative addition directly before [Cl-Mg-Br] dissociates to form the middle product [Ar-Fe(MgBr)] than if the attack occurs after the dissociation of [Cl-Mg-Br]. The solvation effect in this step clearly leads to a lowering of the energy barrier. The rate-limiting step in the whole catalytic cycle is the reductive elimination of [Ar-(n-hexyl)-Fe(MgBr)(2)] to regenerate the catalyst [Fe(MgBr)(2)], where the electronic energy barrier ΔE is 29.74 kcal/mol in the gas phase and the Gibb's free energy in solvent THF ΔG(sol) is 28.13 kcal/mol computed using the C-PCM method.

Highly Ordered Thermoplastic Polyurethane/Aramid Nanofiber Conductive Foams Modulated by Kevlar Polyanion for Piezoresistive Sensing and Electromagnetic Interference Shielding.

Highly ordered and uniformly porous structure of conductive foams is a vital issue for various functional purposes such as piezoresistive sensing and electromagnetic interference (EMI) shielding. With the aids of Kevlar polyanionic chains, thermoplastic polyurethane (TPU) foams reinforced by aramid nanofibers (ANF) with adjustable pore-size distribution were successfully obtained via a non-solvent-induced phase separation. In this regard, the most outstanding result is the in situ formation of ANF in TPU foams after protonation of Kevlar polyanion during the NIPS process. Furthermore, in situ growth of copper nanoparticles (Cu NPs) on TPU/ANF foams was performed according to the electroless deposition by using the tiny amount of pre-blended Ti3C2Tx MXene as reducing agents. Particularly, the existence of Cu NPs layers significantly promoted the storage modulus in 2,932% increments, and the well-designed TPU/ANF/Ti3C2Tx MXene (PAM-Cu) composite foams showed distinguished compressive cycle stability. Taking virtues of the highly ordered and elastic porous architectures, the PAM-Cu foams were utilized as piezoresistive sensor exhibiting board compressive interval of 0-344.5 kPa (50% strain) with good sensitivity at 0.46 kPa-1. Meanwhile, the PAM-Cu foams displayed remarkable EMI shielding effectiveness at 79.09 dB in X band. This work provides an ideal strategy to fabricate highly ordered TPU foams with outstanding elastic recovery and excellent EMI shielding performance, which can be used as a promising candidate in integration of satisfactory piezoresistive sensor and EMI shielding applications for human-machine interfaces.

Reconfigurable Terahertz Spatial Deflection Varifocal Metamirror.

A traditional optical lens usually has a fixed focus, and its focus controlling relies on a bulky lens component, which makes integration difficult. In this study, we propose a kind of terahertz spatial varifocal metamirror with a consistent metal-graphene unit structure whose focus can be flexibly adjusted. The focus deflection angle can be theoretically defined by superimposing certain encoded sequence on it according to Fourier convolution theorem. The configurable metamirror allows for the deflection of the focus position in space. The proposed configuration approach presents a design concept and offers potential advancements in the field of developing novel terahertz devices.

TEMPO-Oxidized Nanofibrillated Cellulose Assisted Exfoliation of MoS2 /Graphene Composites for Flexible Paper-Anodes.

TEMPO-oxidized nanofibrillated cellulose (ONFC) with charged carboxyl groups is introduced for the efficient exfoliation of two-dimensional (2D) MoS2 /graphene composites. As an effective dispersant agent, ONFC can be easily absorbed between the adjacent layers, so as to prevent the accumulation of the exfoliated nanosheets. With the assistance of charged ONFC, the exfoliated MoS2 /graphene is gradually increased in the aqueous dispersions with the elongated sonication time. After dewatering, self-standing MoS2 /Graphene/ONFC/CNTs composite films are rationally constructed using ONFC as flexible fibrous skeleton, and CNTs/graphene as 1D/2D interpenetrating electrical networks. Ultrathin MoS2 nanosheets anchored on the 1D/2D heterogeneous networks is directly acted as an ideal paper-anode for lithium-ion batteries (LIBs) without using traditional metallic current collector. The self-standing flexible electrode materials based on natural cellulose will promote the future green electronics with high flexibility, miniaturization, and increased portability.

Highly thermally conductive Ti3C2Tx/h-BN hybrid films via coulombic assembly for electromagnetic interference shielding.

With the development of electronic equipment, heat problem and electromagnetic pollution severely affect both their functions and human health, which leads to great interests in developing materials synchronously with outstanding thermal conductivity and electromagnetic interference (EMI) shielding performance. Here, ultrathin Ti3C2Tx/h-BN two-dimensional (2D) heterostructure films were prepared via coulombic assembly between Ti3C2Tx MXene and h-BN nanosheet through ultrasonic blending. After the addition of h-BN nanosheet as thermal conductive nanofillers, the hybrid films achieved a higher value of thermal conductivity, compared to Ti3C2Tx composite film without h-BN. The higher thermal conductivity offered by h-BN enables the Ti3C2Tx/h-BN films have good potential for EMI shielding applications on wearable and portable electronic devices. When the mass ratio of Ti3C2Tx/h-BN is 7:3, the hybrid film with the thickness of 47.60 µm exhibited electrical conductivity of 57.67 S/cm and the maximum EMI shielding effectiveness of 37.29 dB.

Interfacial Engineering of Two-Dimensional MoN/MoO2 Heterostructure Nanosheets as a Bifunctional Electrocatalyst for Overall Water Splitting.

It is still a challenge to realize the dream of a hydrogen-based economy using a robust catalyst for overall water splitting. Here, we introduce two-dimensional MoN/MoO2 heterostructure nanosheets using nickel foam as a substrate for water splitting. The heterojunction formation was achieved through the partial nitriding of a Mo-based precursor to MoN in the annealing process under NH3 environment. The heterogeneous interface between MoN and MoO2 as active sites is supposed to improve the surface reaction kinetics and electronic conductivity. Therefore, an excellent performance is achieved when MoN/MoO2 is employed as both cathode and anode electrocatalysts; the corresponding cell voltages are 1.57 and 1.84 V at 10 and 100 mA cm-2 in 1 M KOH, respectively. The promising bifunctional catalytic performance of our catalyst opens up a new way for efficient electrochemical water splitting.

The Prevalence and Characteristics of Chronic Ankle Instability in Elite Athletes of Different Sports: A Cross-Sectional Study.

BACKGROUND: Ankle sprains are one of the most common injuries in athletic populations. Misdiagnosed and untreated ankle sprains will cause chronic ankle instability (CAI), which can significantly affect the performance of athletes. This study aimed to investigate the prevalence and characteristics of CAI in elite athletes of different sports. METHOD: This cross-sectional study included 198 elite athletes from Guangdong provincial sports teams. All participants answered a questionnaire about ankle sprains and ankle instability. The severity of their ankle instability was evaluated by the Cumberland Ankle Instability Tool (CAIT). Participants further underwent clinical examinations from sports medicine doctors to determine the presence and characteristics of ankle instability. The datasets were analyzed to determine the differences in prevalence between age, gender, sports teams, and sports categories. RESULTS: In 198 athletes, 39.4% (n = 78) had bilateral CAI while 25.3% (n = 50) had unilateral CAI. Female athletes had a higher prevalence of CAI than male athletes in the study (p = 0.01). Prevalence showed differences between sports categories, and were significantly higher in acrobatic athletes than non-contact athletes (p = 0.03). CONCLUSIONS: CAI was highly prevalent among elite athletes in this study, with female athletes and athletes in acrobatic sports being associated with a higher risk of developing CAI in their professional careers. Therefore, extra precautions need to be taken into account when applying ankle protections for these athletes.

Monitoring colorless electroactive chemicals in complex background based on electrochemical difference absorption spectroscopy with twin flow cells.

Conventional UV/Vis absorption spectroscopy is an economical and user-friendly technique for online monitoring, however, by which some electroactive chemicals are hardly determined in the presence of fluctuating background due to the formation of colored chemicals. Here, we propose an electrochemical difference absorption spectroscopy (EDAS) to accurately quantify colorless chemicals based on visible color change via electrolysis with strong variation in the background. EDAS is realized by twin spectroelectrochemical flow cells system, replacing the two cuvette cells of a dual beam spectrophotometer. Each cell consists of a three-electrode system, quartz windows and a thin flow channel. Flowing of analyte from one cell (reference cell) to the other (sample cell) can eliminate the influence of colored interferents even while their concentrations are changing. When different potentials are applied on the sample and reference cells respectively, electrolysis occurs and colored products flowing through quartz windows can absorb the incident light, resulting in difference absorption spectra induced from potential difference. We find that steady-state difference absorbance (ΔA) at characteristic wavelength is linearly changed with sample concentrations. EDAS is firstly verified by Fe(CN)64- at different potentials and flow rates, in good agreements with a simplified theory that describes linear relationship between ΔA and analyte concentration. Then EDAS is used to determine Cu(I) in Cu(I)-Cu(II) mixed solutions and tetramethylbenzidine in its partially oxidized solutions to illustrate the powerful ability to detect colorless chemicals with varied background, implying its promising potential applications in the chemical industry.

Yarn-ball-shaped CNF/MWCNT microspheres intercalating Ti3C2Tx MXene for electromagnetic interference shielding films.

Ti3C2Tx MXenes with excellent metallic conductivity have proved promising in its application of electromagnetic interference (EMI) shielding. A hierarchical hybrid film with ultrathin thickness composed of Ti3C2Tx MXene layers embedded with yarn-ball-shaped microspheres of cellulose nanofibrils (CNF) and multiwalled carbon nanotube (MWCNT) was designed to improve the absorption of electromagnetic waves (EMWs). The addition of yarn-ball-shaped microspheres is to shield more EMWs via multiple reflections in the inner space and reduce the undesirable emissions into the air. After thermal annealing treatment, the ultrathin film with intercalation of the carbonized yarn-ball-shaped CNF/MWCNT microspheres exhibited enhanced EMWs absorption as an important part of shielding effectiveness (45.1±0.9 dB) as well as excellent mechanical stability (≈0.9 million bending times). Thus, the well-designed structure of multilayered hybrid films with intercalated conductive microspheres can be a good candidate for higher absorption in EMI shielding effectiveness and outstanding mechanical properties.

Reconstruction of pH-universal atomic FeNC catalysts towards oxygen reduction reaction.

Constructing of single atom catalysts that can stably exist in various energy conversion and storage devices is still in its infancy. Herein, a geometrically optimized three-dimensional hierarchically architectural single atomic FeNC catalyst with fast mass transport and electron transfer is rationally developed by post-molecule pyrolysis assisted with silicon template and reconstructs by ammonia treating. The ammonia-assisted secondary pyrolysis not only compensates for the volatilization of nitrogen species contained in organic precursors but also optimizes the surface structure of FeNC catalyst, thus increasing the content of pyridinic nitrogen and boosting the density of active sites (FeNx) in FeNC samples. In addition, the pyridinic nitrogen adjusts the electronic distribution in Fe 3d active center and promotes the catalytic performances. Therefore, this hollow spherical atomically dispersed FeNC catalyst delivers outstanding oxygen reduction reaction (ORR) activity in pH-universal electrolyte and surpasses the most reported values.