Time crystals are periodic states exhibiting spontaneous symmetry breaking in either time-independent or periodically-driven quantum many-body systems. Spontaneous modification of discrete ...time-translation symmetry in periodically-forced physical systems can create a discrete time crystal (DTC) constituting a state of matter possessing properties like temporal rigid long-range order and coherence, which are inherently desirable for quantum computing and information processing. Despite their appeal, experimental demonstrations of DTCs are scarce and significant aspects of their behavior remain unexplored. Here, we report the experimental observation and theoretical investigation of DTCs in a Kerr-nonlinear optical microcavity. Empowered by the self-injection locking of two independent lasers with arbitrarily large frequency separation simultaneously to two same-family cavity modes and a dissipative Kerr soliton, this versatile platform enables realizing long-awaited phenomena such as defect-carrying DTCs and phase transitions. Combined with monolithic microfabrication, this room-temperature system paves the way for chip-scale time crystals supporting real-world applications outside sophisticated laboratories.
Additive manufacturing (AM) is currently a widely used technology, even though a more profound understanding is still needed to track and identify defects during AM. The acoustic emission (AE) ...approach has gained a reputation in non-destructive testing (NDT) as one of the most influential and proven techniques in numerous engineering fields. Material testing through AE has become one of the most popular techniques in AM because of its capability to detect defects and anomalies, monitoring, and the progress of flaws. Various AE techniques have been under investigation for in-situ monitoring of AM. The preliminary results from AE exploration show promising results that need further investigation on data analysis and signal processing. AE monitoring technique allows finding the defects during the fabrication process so that the AM failure can be prevented or the process can be finely tuned to avoid damages or material waste. In this work, AE data recorded over the Direct Energy Deposition (DED) additive manufacturing process analyzed by machine learning (ML) algorithm for classification of different build conditions. The feature extraction method is used to obtain the required data for further processing. Wavelet transformation of signals has been used to acquire the time-frequency spectrum of the AE signals at each process condition, and convolutional neural network (CNN) image processing is used to identify the transformed spectrum of different build conditions. The identifiers in AE signals are correlated to the part quality by statistical methods. The results show a promising approach for quality evaluation and process monitoring in AM.
Carbon- and glass fiber-reinforced polymer (CFRP and GFRP) composite materials have been used in many industries such as aerospace and automobile because of their outstanding strength-to-weight ratio ...and corrosion resistance. The quality of these materials is important for safe operation. Nondestructive testing (NDT) techniques are an effective way to inspect these composites. While ultrasonic NDT has previously been used for inspection of composites, conventional ultrasonic NDT, using single element transducers, has limitations such as high attenuation and low signal-to-noise ratio (SNR). Using phased array ultrasonic testing (PAUT) techniques, signals can be generated at desired distances and angles. These capabilities provide promising results for composites where the anisotropic structure makes signal evaluation challenging. Defect detection in composites based on bulk and guided waves are studied. The capability of the PAUT and its sensitivity to flaws were evaluated by comparing the signal characteristics to the conventional method. The results show that flaw sizes as small as 0.8 mm with penetration depth up to 25 mm can be detected using PAUT, and the result signals have better characteristics than the conventional ultrasonic technique. In addition, it has been shown that guided wave generated by PAUT also has outstanding capability of flaw detection in composite materials.
Nondestructive evaluation (NDE) techniques are used in many industries to evaluate the properties of components and inspect for flaws and anomalies in structures without altering the part's integrity ...or causing damage to the component being tested. This includes monitoring materials' condition (Material State Awareness (MSA)) and health of structures (Structural Health Monitoring (SHM)). NDE techniques are highly valuable tools to help prevent potential losses and hazards arising from the failure of a component while saving time and cost by not compromising its future usage. On the other hand, Artificial Intelligence (AI) and Machine Learning (ML) techniques are useful tools which can help automating data collection and analyses, providing new insights, and potentially improving detection performance in a quick and low effort manner with great cost savings. This paper presents a survey on state of the art AI-ML techniques for NDE and the application of related smart technologies including Machine Vision (MV) and Digital Twins in NDE.
Abstract The research literature suggests that oxidative stress and pro-inflammatory factors influence neurotrophins in vitro. However, there is insufficient information about their effects on ...exercise training conditions, especially during high intensity trainings. This study aimed to compare the effects of 6 weeks of high intensity interval and continuous training regimens on brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF), hydrogen peroxide (H2 O2 ), and tumor necrosis factor alpha (TNF-α) in the rat brain. For this purpose, twenty-four Albino Wistar rats were divided into sedentary control (SC), high intensity interval training (HIIT), and continuous training (CT) groups. Both HIIT and CT regimens increased H2 O2 level and TNF-α concentration in the brain, and the alterations made were greater following HIIT than CT. In addition, both HIIT and CT regimens increased BDNF and GDNF concentrations significantly, with a higher elevation following HIIT than CT. Furthermore, H2 O2 level and TNF-α concentration correlated positively with both BDNF and GDNF concentrations. Generally, high intensity interval training regimen, rather than continuous training regimen, is highly potential to improve BDNF and GDNF through a greater increase in H2 O2 and TNF-α as oxidative stress and pro-inflammatory factors.
In this review, the potential failures and flaws associated with fused deposition modeling (FDM) or fused filament fabrication (FFF) 3D printing technology are highlighted. The focus of this article ...is on presenting the failures and flaws that are caused by the operational standpoints and which are based on the many years of experience with current and emerging materials and equipment for the 3D printing of polymers and composites using the FDM/FFF method. FDM or FFF 3D printing, which is also known as an additive manufacturing (AM) technique, is a material processing and fabrication method where the raw material, usually in the form of filaments, is added layer-by-layer to create a three-dimensional part from a computer designed model. As expected, there are many advantages in terms of material usage, fabrication time, the complexity of the part, and the ease of use in FDM/FFF, which are extensively discussed in many articles. However, to upgrade the application of this technology from public general usage and prototyping to large-scale production use, as well as to be certain about the integrity of the parts even in a prototype, the quality and structural properties of the products become a big concern. This study provides discussions and insights into the potential factors that can cause the failure of 3D printers when producing a part and presents the type and characteristics of potential flaws that can happen in the produced parts. Common defects posed by FDM printing have been discussed, and common nondestructive detection methods to identify these flaws both in-process and after the process is completed are discussed. The discussions on the failures and flaws in machines provides useful information on troubleshooting the process if they happen, and the review on the failures and flaws in parts helps researchers and operators learn about the causes and effects of the flaws in a practical way.
Due to unknown aetiology of Thromboangiitis obliterans (TAO), its effectively treating is challenging. However, angiogenesis induction is one of the acceptable treatments for TAO patients. Recently, ...we have noticed that TAO patients who were under long-term treatment with angiogenesis-inducing medication showed considerable improvement in terms of healing chronic ulcers over the course of one to 2 years of treatment. However, some of them developed dermal gangrene despite the warming of their feet, with or without palpable pulses in the extremities, and with hair growth on the affected skin. Unfortunately, following the progression of dermal gangrene, some of these patients had to undergo amputation and limb loss.During histopathological evaluation, we detected some changes in the amputee TAO patients under long-term angiogenic medical treatment that were not present in amputee TAO patients who had not received any treatment for many years. The greatest pathological changes were observed in the microvascular of the skin, appearing as a proliferation of endothelial cells, NETosis and thrombus formation inside the vessels with proliferation of endothelial cells. The immunohistochemistry for CD31 and Ki67 as markers of vascular endothelium differentiation and cell mitosis confirmed the proliferation of endothelial cells. However, in the patients who had not received any treatment for years the typical pathology view of BD, including preserved vascular architecture with infiltration of inflammatory cells and inflammatory cells inside the thrombus, organised thrombus with recanalisation and intimal thickening was observed. Further longitudinal cohort studies regarding long-term treatment with angiogenic medications for TAO in different geographic areas are highly recommended.
Cellulose acetate (CA) is considered as one of the first materials used in membrane technology. However, CA membranes suffered finding their way for widespread commercial applications due to low ...mechanical stability and sensitivity to bio-fouling. In this study a green procedure was developed to overcome some of CA drawbacks in membrane applications. For this purpose 2nd generation of hyperbranched poly(amine ester) (HBPAE-G2), was synthesized using methyl 3-bis(2-hydroxyethyl)aminopropanoate and triethanolamine through a pseudo one-pot polycondensation, reacted with soybean oil fatty acid, and then double bonds epoxidized by H
2
O
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/formic acid to acquire hyperbranched poly(amine ester)-epoxidized soybean oil (HBPAE-ESBOFA). Finally, this reactive additive was blended with CA membrane dope solution to obtain simultaneously plasticized and cross-linked structure. Synthesis procedures were monitored by FTIR and NMR techniques, and membrane samples were investigated using ATR-FTIR, FE-SEM (top and cross-sectional), TGA and DSC. Filtration properties were studied by determining pure water flux, water contact angle, bio-fouling, water content, mean pore size and solute rejection tests. Permeability tests showed decline in water flux, but fouling resistance, salt rejection and thermal properties improved. Moreover, modified samples showed fascinating flexibility and mechanical stability enhanced dramatically.
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