Search Results (21)

The paper proposes a manufacturing technology for the non-woven/3D-printed (N3DP) hybrid material (HM) with improved radio-absorbing properties. We have fabricated the needle-punched non-woven felt and impregnated it with the carbon fibers containing UV-curable photopolymer resin. The functional 3D-printed layer was attached to the highly porous, deformable polymer substrate by the fused deposition modeling (FDM) technique. The preliminary bulk modification of the filament was realized with the IR- and UV-pigment microcapsules filling. The combination of additive prototyping and non-woven needle-punched fabrics surface modification (by the electrically conductive elements 2D-periodic system applying) expands the frequency range of the electromagnetic radiation effective absorption. It provides the possibility of a reversible change in the color characteristics of the hybrid material surface under the influence of the UV and IR radiation. Full article

Background: This study aimed to develop a method to analyze the kinetic and kinematic characteristics of the traditional karate Gyaku Tsuki (reverse punch), focusing on the activation sequence of lower and upper extremities and trunk muscles during execution. Methods: An elite male (N = 1) karate athlete (in kata) performed 20 Gyaku Tsuki punches while equipped with 16 wireless surface EMG sensors integrated with 3-axis accelerometers. The five punches with the highest forearm acceleration were selected for analysis. EMG, accelerometer, and synchronized video data were recorded and processed. Results: A novel visualization technique was developed to represent muscle activation over time, distinguishing a spectrum of 0–25–50–75–100% activation levels. Muscle activation times for arm, leg, and trunk muscles ranged from −0.31 to −0.11 s relative to punch execution, indicating rapid, coordinated muscle engagement. Conclusions: This method enables detailed analysis of muscle activation patterns in karate punches. It offers valuable insights for biomechanics researchers and practical applications for coaches aiming to enhance performance and prevent injuries through better understanding of movement dynamics. Full article

Conventional material aging and testing protocols involve exposing coupon samples to saturation in application fluid(s) at temperature and pressure conditions typically encountered during service, followed by mechanical testing at ambient conditions. This practice can generate misleading results for materials for which fluid ingress is rapidly reversible, most notably at elevated temperatures. A recently developed in situ punch–shear device has been successfully used to establish experimental correlations between the tensile properties (ASTM D638) and shear properties (ASTM D732) of Polyethylene of Raised Temperature (PERT) under dry conditions. It also enabled measurement of shear properties of select polymers while immersed (saturated) in fluids at elevated pressure and temperature. The present work extends the treatment to a suite of commercially available thermoplastic polymers spanning the commodity, engineering, and high-performance polymer grades with varying degrees of hygroscopicity. The objectives of this contribution are three-fold, namely: (i) assess the effect of sample preparation method on measured mechanical properties, (ii) compare the experimentally established correlations between shear and tensile tests for the different class of polymer grades before fluid exposure, and (iii) gauge reversibility of the measured tensile and shear properties after aging in deionized water to saturation at 95 °C. Results indicate that (i) the test coupon preparation method affects the tensile to shear correlation and must be standardized to enable systematic comparison of in situ properties, (ii) individual correlations segregate by polymer family, and (iii) conventional tensile testing after a saturation–dehydration cycle yields optimistic mechanical properties. Full article

Background: In karate, the ability to execute high-velocity movements, particularly kicks and punches, is heavily dependent on the strength and power of the lower limb muscles, especially the knee extensors. As such, this study aimed to evaluate the effects of an 8-week eccentric training program utilizing the reverse Nordic exercise (RNE) integrated into karate training compared with regular karate training only on measures of physical fitness in youth karate athletes. Methods: Twenty-seven youth karatekas were recruited and allocated to either RNE group (n = 13; age = 15.35 ± 1.66 years; 7 males and 6 females) or an active control group ([CG]; n = 14; 7 males and 7 females; age = 15.30 ± 1.06 years). To track the changes in measures of physical fitness before and after training, tests to assess linear sprint speed (i.e., 10 m), change of direction (CoD) speed (i.e., modified 505 CoD), vertical jumping (i.e., countermovement jump [CMJ] height) and horizontal jumping distance (i.e., standing long jump [SLJ]), and lower-limb asymmetry score (i.e., the difference between SLJ-dominant and non-dominant legs) were carried out. Results: The results indicated significant group-by-time interactions in all measures of physical fitness (effect size [ES] = 1.03 to 2.89). Post-hoc analyses revealed significant changes in the RNE group across all performance measures (effect size [ES] = 0.33 to 1.63). Additionally, the asymmetry score exhibited a moderate decrease from pre to posttest (∆46.96%, ES = 0.64). In contrast, no significant changes were observed in the CG across all fitness measures. Moreover, the individual response analysis indicated that more karatekas from the RNE group consistently achieved improvements beyond the smallest worthwhile change threshold across all fitness measures. Conclusions: In summary, RNE training is an effective approach to enhance various physical fitness measures besides lower-limb asymmetry scores in youth karatekas and is easy to incorporate into regular karate training. Practitioners are therefore encouraged to consistently integrate RNE training to enhance essential physical fitness components in young karatekas. Full article

The possibility of controlling the porosity and, as a result, the permeability of fibrous non-woven fabrics was studied. Modification of experimental samples was performed on equipment with adjustable heating and compression. It was found that the modification regimes affected the formation of the porous structure. We found that there was a relationship between the permeability coefficient and the porosity coefficient of the materials when the modification speed and temperature were varied. A model is proposed for predicting the permeability for modified material with a given porosity. As the result, a new hybrid composite material with reversible dynamic color characteristics that changed under the influence of ultraviolet and/or thermal exposure was produced. The developed technology consists of: manufacture of the non-woven needle-punched fabrics, surface structuring, material extrusion, additive manufacturing (FFF technology) and the stencil technique of ink-layer adding. In our investigation, we (a) obtained fibrous polymer materials with a porosity gradient in thickness, (b) determined the dependence of the material’s porosity coefficient on the speed and temperature of the modification and (c) developed a model for calculating the porosity coefficient of the materials with specified technological parameters. Full article

Since the avalanche phenomenon was first found in bulk materials, avalanche photodiodes (APDs) have been exclusively investigated. Among the many devices that have been developed, silicon APDs stand out because of their low cost, performance stability, and compatibility with CMOS. However, the increasing industrial needs pose challenges for the fabrication cycle time and fabrication cost. In this work, we proposed an improved fabrication process for ultra-deep mesa-structured silicon APDs for photodetection in the visible and near-infrared wavelengths with improved performance and reduced costs. The improved process reduced the complexity through significantly reduced photolithography steps, e.g., half of the steps of the existing process. Additionally, single ion implantation was performed under low energy (lower than 30 keV) to further reduce the fabrication costs. Based on the improved ultra-concise process, a deep-mesa silicon APD with a 140 V breakdown voltage was obtained. The device exhibited a low capacitance of 500 fF, the measured rise time was 2.7 ns, and the reverse bias voltage was 55 V. Moreover, a high responsivity of 103 A/W@870 nm at 120 V was achieved, as well as a low dark current of 1 nA at punch-through voltage and a maximum gain exceeding 1000. Full article

Within the rapidly growing market for fiber-reinforced plastics (FRPs), conventional production processes involving molds are not cost-efficient for prototype and small series production. Therefore, new flexible forming techniques are increasingly being researched, many of which have been inspired by incremental sheet metal forming (ISF). Due to the different deformation mechanisms of woven reinforcement fibers and metal sheets, ISF is not directly applicable to FRP. Instead, shear and bending of the fibers need to be realized. Therefore, a new dieless forming process for the production of FRP supported by metal wire mesh as an auxiliary material is proposed. Two standard tools, such as hemispherical punches, are used to locally bend a reversible layup of metal wire mesh and woven reinforcement fiber fabric enclosed in a vacuum bag. Therefore, the mesh aids in introducing shear into the material due to its ability to transmit compressive in-plane forces, and it ensures that the otherwise flexible fabric maintains the intended deformation until the part is cured or solidified. Basic experiments are conducted using thermoset prepreg, woven commingled yarn fabric, and thermoplastic organo sheets, proving the feasibility of the approach. Full article

The influence of joint motion on punch efficiency before impact is still understudied. The same applies to the relationship between the kinematic and temporal parameters of a reverse punch (RP) that determines a score. Therefore, the aim of this study was to investigate if the exclusion or inclusion of body segments affects the acceleration, velocity, rotation angle, and timeline of execution, and to examine the correlation between these quantities. Seven elite male competitors—senior European and World Championship medalists—participated in the in-field testing. Quantities were acquired in the developmental phase of RP through three modalities of execution. Synchronized real-time data were obtained using combined multimodal sensors and camera fusion. The main findings of the study have highlighted the significant differences in the temporal and kinematic variables of RP that arise from the modality of execution. Large and medium correlation coefficients were obtained between the examined variables of body and hand. In conclusion, the results show that measured parameters are affected by segmental body activation. Moreover, their interdependence influences punch execution. The presented interdisciplinary approach provides insightful feedback for: (i) development of reliable and easy-to-use technical solutions in combat sports monitoring; and (ii) improvements in karate training. Full article

Janus kinase (JAK)/signal transducer and activator of transcription signaling (STAT) has been implicated in the pathophysiology of hidradenitis suppurativa (HS). This study evaluated treatment-related transcriptomic and proteomic changes in patients with moderate-to-severe HS treated with the investigational oral JAK1-selective inhibitor povorcitinib (INCB054707) in two phase 2 trials. Lesional skin punch biopsies (baseline and Week 8) were taken from active HS lesions of patients receiving povorcitinib (15 or 30 mg) once daily (QD) or a placebo. RNA-seq and gene set enrichment analyses were used to evaluate the effects of povorcitinib on differential gene expression among previously reported gene signatures from HS and wounded skin. The number of differentially expressed genes was the greatest in the 30 mg povorcitinib QD dose group, consistent with the published efficacy results. Notably, the genes impacted reflected JAK/STAT signaling transcripts downstream of TNF-α signaling, or those regulated by TGF-β. Proteomic analyses were conducted on blood samples obtained at baseline and Weeks 4 and 8 from patients receiving povorcitinib (15, 30, 60, or 90 mg) QD or placebo. Povorcitinib was associated with transcriptomic downregulation of multiple HS and inflammatory signaling markers as well as the reversal of gene expression previously associated with HS lesional and wounded skin. Povorcitinib also demonstrated dose-dependent modulation of several proteins implicated in HS pathophysiology, with changes observed by Week 4. The reversal of HS lesional gene signatures and rapid, dose-dependent protein regulation highlight the potential of JAK1 inhibition to modulate underlying disease pathology in HS. Full article

Karate fighters are under constant pressure to find adequate scoring solutions in ever-changing combat conditions. Thus, technique improvement at high levels of mastery demands a novel approach to key data acquisition and in-depth analysis of more than just the impact phase in punch execution. With the aim of describing the kinematic and temporal structure of a reverse punch in the developmental phase, two wireless sensors were used for the acquisition of selected quantities in ten modalities performed by a continental and world medallist. The results show that the timeline of kinematic parameters may be a reliable factor regarding the efficiency of the reverse punch. The obtained hand results show a tendency towards maintaining greater levels of stability in comparison to the body. Additionally, the differences between parameters in relation to applied tests that replicated training and combat conditions were noted. The highest acceleration values were obtained in sliding motion preceding RP, with a partner holding chest punch pad, both static (7.35 ± 0.47 g₀) and dynamic (6.99 ± 1.23 g₀) tests. The same applies for velocity (8.39 ± 0.14 and 7.30 ± 1.28 m/s). The obtained results indicate the need for specific testing and an individual approach in the analysis of the techniques of elite competitors, along with the use of sensors in data acquisition. Such an approach may help improve the training and competition practice of karate fighters. Full article

Fetal programming is the concept that maternal stressors during critical periods of fetal development can alter offspring phenotypes postnatally. Excess glucocorticoids can interact with the fetus to effect genetic and epigenetic changes implicated in adverse developmental outcomes. The present study investigates how chronic exposure to the synthetic glucocorticoid dexamethasone during late gestation alters the expression of genes related to behavior in brain areas relevant to the regulation and function of the hypothalamic–pituitary–adrenal axis. Pregnant Wistar Kyoto rats received subcutaneous injections of dexamethasone (100 μg/kg) daily from gestational day 15–21 or vehicle only as sham controls. The amygdala and paraventricular nucleus (PVN) were micro-punched to extract mRNA for reverse transcription and quantitative polymerase chain reaction for the analysis of the expression of specific genes. In the PVN, the expression of the glucocorticoid receptor NR3C1 was downregulated in female rats in response to programming. The expression of CACNA1C encoding the Ca_v1.2 pore subunit of L-type voltage-gated calcium channels was downregulated in male and female rats prenatally exposed to dexamethasone. Collectively, the results suggest that prenatal exposure to elevated levels of glucocorticoids plays a role in the dysregulation of the hypothalamic–pituitary–adrenal axis and potentially learning and memory by altering the expression of specific genes within the amygdala and PVN. Full article

A novel elevated-temperature and high-pressure in situ punch-shear-test cell was developed to qualify materials for reliable service in harsh environments representative of those typically encountered in oil and gas operations. The proposed modular and compact test device is an extension of the ASTM D 732 punch-shear method. Conventionally, materials are first exposed to harsh environments, then removed from the aging environment for mechanical testing. This practice can lead to the generation of unrealistic (often optimistic) mechanical properties. This is especially true in the case of materials for which fluid ingress is reversible. The present contribution elaborates on the developed in situ punch-shear device that has been successfully used to realistically assess the tensile yield strength and modulus properties of in-service polymer materials based on experimentally established correlations between shear and tensile tests. Full article

To address the problem whereby the size of the hole formed by the existing hole-forming device of hole-punching transplanters is significantly inconsistent with the theoretical size as it is impacted by the inserting and lifting methods, a scheme for eliminating the forward speed of the whole machine by the horizontal linear velocity of reverse rotation of the hole-forming mechanism is proposed to vertically insert and lift the hole-forming device in accordance with the working characteristics of hole-punching transplanting and the agronomic requirements of rapeseed transplanting. In addition, a novel type of reverse-rotating soil-taking-type hole-forming device for the pot seedling transplanting machine for rapeseed was developed. A test bench for the hole-forming device was set and its effectiveness was verified in the soil bin. It was found, from the test results, that, when the forward speed of the hole-forming device was between 0.25 m/s and 0.45 m/s, the average qualified rates of hole forming of the device were 95.2%, 94.0% and 93.3%, respectively; the average change rates of the hole size were 2.3%, 2.9% and 5.5%, respectively; and the average error between the theoretical value of effective depth and the experimental value was between 2.0% and 5.6%. The average angle between the hole-forming stage trajectory of the hole opener and the horizontal direction at different forward speeds was higher than 88.0°; the coefficient of variation was between 0.16% and 0.64%; the perpendicularity of the hole-forming operation was high; the change rates of soil porosity of the hole wall were between 8.2% and 9.3%; and the average soil heave degrees at the hole mouth after the completion of the hole-forming operation were 3.9%, 4.1% and 4.2%, respectively. The average soil stability rates of the hole wall were 91.9%, 91.2% and 91.0%, respectively. The different performances of the hole-forming device were confirmed to meet the requirements of rapeseed pot seedling transplanting. This study can provide a reference for the structural improvement and optimization of the hole-punching transplanter for rapeseed pot seedlings. Full article

Friction is one of the important factors in sheet metal forming. It greatly affects dynamic behaviors of metal sheets and stress and strain distributions in the metal sheets. In this study, deformation characteristics, stress–strain distribution, and change law of symmetrical parts in the process of deep drawing are analyzed using a new theoretical model based on the plastic flow law and partitioning the forming area. In the model, the least-square method is used to linearize the friction coefficient in nonlinear problems and reverse the calculation of friction coefficients to interpret the friction coefficient. To evaluate the model, the friction coefficient in sheet metal drawing of axis-symmetric deep drawing parts under various friction conditions was measured using a self-developed measuring system. The comparison between the experimental results and the calculation using the model shows a good agreement. The results show that the drawing force increases with the increase in punch depth; the friction coefficient decreases with the rise in punch depth. The friction coefficient obtained by fitting is relatively stable, and the average error is less than 3%. Using the friction coefficient model in finite element simulation analysis, it shows that the thickness and blank shape errors are less than 5%. The novel method studied in this paper shows great significance in support for theoretical research, numerical simulation research, and sheet metal stamping performance evaluation. Full article

The delayed and impaired wound healing caused by dexamethasone (DEX) is commonly reported. Puerarin, the major isoflavone found in Pueraria montana var. lobata (Willd.) Sanjappa & Pradeep promoted the wound healing process in diabetic rats. However, the effects and underlying mechanisms of puerarin on DEX-impaired wound healing have not been investigated. This study examined the potential uses of puerarin in upregulating keratinocyte proliferation and migration in dexamethasone (DEX)-suppressed wound healing model. The effects of puerarin on wound healing in vivo were investigated by taking full-thickness 5 mm punch biopsies from the dorsal skin of BALB/c mice and then treating them topically with 0.1% DEX. For the in vitro study, DEX-treated HaCaT cells were used to examine the effects of puerarin on DEX-induced keratinocyte proliferation and migration and the mechanisms of its action. Puerarin, when applied topically, accelerated the wound closure rate, increased the density of the capillaries, and upregulated the level of collagen fibers and TGF-β in the wound sites compared to the DEX-treated mice. Puerarin promoted the proliferation and migration of keratinocytes by activating the ERK and Akt signaling pathways in DEX-treated HaCaT cells. In conclusion, puerarin could be effective in reversing delayed and disrupted wound healing associated with DEX treatments. Full article