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Aging is a process that represents the accumulation of changes in organism overtime. In biological level, accumulations of molecular and cellular damage in aging lead to an increasing risk of diseases like sarcopenia. Sarcopenia reduces mobility, leads to fall‐related injuries, and diminishes life quality. Thus, it is meaningful to find out novel therapeutic strategies for sarcopenia intervention that may help the elderly maintain their functional ability. Oxidative damage‐induced dysfunctional mitochondria are considered as a culprit of muscle wasting during aging. Herein, we aimed to demonstrate whether myricanol (MY) protects aged mice against muscle wasting through alleviating oxidative damage in mitochondria and identify the direct protein target and its underlying mechanism. We discovered that MY protects aged mice against the loss of muscle mass and strength through scavenging reactive oxygen species accumulation to rebuild the redox homeostasis. Taking advantage of biophysical assays, peroxiredoxin 5 was discovered and validated as the direct target of MY. Through activating peroxiredoxin 5, MY reduced reactive oxygen species accumulation and damaged mitochondrial DNA in C2C12 myotubes. Our findings provide an insight for therapy against sarcopenia through alleviating oxidative damage‐induced dysfunctional mitochondria by targeting peroxiredoxin 5, which may contribute an insight for healthy aging. [ABSTRACT FROM AUTHOR]

Malaria continues to pose a serious global health threat, and artemisinin remains the core drug for global malaria control. However, the situation of malaria resistance has become increasingly severe due to the emergence and spread of artemisinin resistance. In recent years, significant progress has been made in understanding the mechanism of action (MoA) of artemisinin. Prior research on the MoA of artemisinin mainly focused on covalently bound targets that are alkylated by artemisinin‐free radicals. However, less attention has been given to the reversible noncovalent binding targets, and there is a paucity of information regarding artemisinin targets at different life cycle stages of the parasite. In this study, we identified the protein targets of artemisinin at different stages of the parasite's intraerythrocytic developmental cycle using a photoaffinity probe. Our findings demonstrate that artemisinin interacts with parasite proteins in vivo through both covalent and noncovalent modes. Extensive mechanistic studies were then conducted by integrating target validation, phenotypic studies, and untargeted metabolomics. The results suggest that protein synthesis, glycolysis, and oxidative homeostasis are critically involved in the antimalarial activities of artemisinin. In summary, this study provides fresh insights into the mechanisms underlying artemisinin's antimalarial effects and its protein targets. Highlights: We identified the targets of artemisinin at different stages of the intraerythrocytic cycle of Plasmodium falciparum using a photoaffinity probe of artemisinin.Artemisinin can interact with parasite proteins in vivo through both covalent and noncovalent mechanisms.Artemisinin may exert its antimalarial effects by interfering with the parasite's protein synthesis, glycolysis, and oxidative homeostasis pathways.This study provides fresh insights into the mechanisms underlying artemisinin's antimalarial effects and its protein targets. [ABSTRACT FROM AUTHOR]

Alkaloids represent a large family of natural products with diverse structures and bioactivities. These compounds and their derivatives have been widely used in clinics to treat various diseases. The endophytic Aspergillus is a filamentous fungus renowned for its extraordinary ability to produce active natural products of high therapeutic value and economic importance. This review is the first to focus on Aspergillus-derived alkaloids. Through an extensive literature review and data analysis, 263 alkaloids are categorized according to their structural features into those containing cytochalasans, diketopiperazine alkaloids, quinazoline alkaloids, quinoline alkaloids, indole alkaloids, pyrrolidine alkaloids, and others. These metabolites exhibited diverse biological activities, such as antibacterial activity, cytotoxicity, anti-inflammatory activity, and α-glucosidase, ACE, and DPPH inhibitory activities. The bioactivity, structural diversity, and occurrence of these alkaloids are reviewed in detail. [ABSTRACT FROM AUTHOR]

In the flexible photovoltaic (PV) industry, increment of the metal‐organic chemical vapor deposition (MOCVD) deposition zone is crucial to reducing the cost of ownership and increasing the power conversion efficiency (PCE). This implies that the larger closed coupled showerhead (CCS) of MOCVD system should be used in the manufacture of flexible gallium arsenide (GaAs) PV thin‐film solar cells. Currently, Aixtron Crius II is the largest commercial CCS reactor for GaAs deposition with 55 × 2 inches circular wafers. As the size of the carrier and showerhead increases, the deposition uniformity and gas flow stability become more difficult to control. To address these issues, previous studies have investigated the effects of geometric and process parameters of MOCVD on the vertical process gas inlet, with either a rotating carrier model represented by Veeco using high‐speed rotating carrier (Turbo Disc), and Aixtron using low‐speed rotating planetary carrier, or a horizontal process gas injector with a rotating carrier. However, these efforts have limited further capacity scale‐up. In this study, numerical simulations and fluid visualization experiments are conducted, based on previous research on thermal uniformity, for design optimization of a gas distribution system in a large square GaAs‐MOCVD reactor. The achieved reactor capacity is 36 × 4 inches square wafers in one process cycle, and the optimal average deposition rate and deposition uniformity of GaAs film are ≈0.430 µm min−1 and 0.93%, respectively. [ABSTRACT FROM AUTHOR]

Breast cancer is the leading cause of cancer-related mortality in women worldwide. Despite the rapid developments in diagnostic techniques and medical sciences, pathologic diagnosis is still recognized as the gold standard for disease diagnose. Pathologic diagnosis is a time-consuming task performed for pathologists, needing profound professional knowledge and long-term accumulated diagnostic experience. Therefore, the development of automatic and precise histopathological image classification is essential for medical diagnosis. In this study, an improved VGG network was used to classify the breast cancer histopathological image from intraoperative rapid frozen sections. We adopt a transformed loss function by adding a penalty to cross-entropy in our training stage, which improved the accuracy on test data by 4.39%. Laplacian-4 was used for the enhancement of images, which contributes to the improvement of the accuracy. The accuracy of the proposed model on training data and test data reached 88.70% and 82.27%, respectively, which outperforms the original model by 9.39% of accuracy in test data. The process time was less than 0.25 s per image on average. Meanwhile, the heat maps of predictions were given to show the evidential regions in histopathological images, which could drive improvements in the accuracy, speed, and clinical value of pathological diagnoses. In addition to helping with the actual diagnosis, this technology may be a benefit to pathologists, surgeons, and patients. It might prove to be a helpful tool for pathologists in the future. [ABSTRACT FROM AUTHOR]

Improved designs for underwater manipulators are becoming increasingly important due to their utility in academic and industrial applications. In this work, an experiment was conducted in conjunction with a numerical simulation to investigate the hydrodynamic performance and structural reliability of the proposed foldable arm during the unfolding process at various movement velocities. A large-scale geometric model of the foldable arm with a single degree of freedom (DOF) was constructed. The distribution of the flow field, the movement stability and the equivalent stress of the foldable arm were quantitatively analyzed with a designed tank experiment and the Computational Fluid Dynamics (CFD) simulation. Simulation results show that the maximum deviation of the resistance and torque is 8.04% and 5.73%, respectively, compared with the experimental results of static postures. Comparison results prove the reliability of the numerical model. The results of transient simulation demonstrate that the optimal speed of the foldable arm is 3 Kn and the pressure distribution on the surface of foldable arm is relatively regular. Furthermore, a fluid–structure interaction (FSI) validation study of the foldable arm was presented. For the coupling between the fluid and structural mechanics domains, a nonmatching discretization approach was adopted. The results show that the directional deformation (Z axis) of the foldable arm is less than 0.50 mm. The proposed foldable arm has a large angle of rotation and high stability compared to the existing manipulators. [ABSTRACT FROM AUTHOR]

Over 766 million people have been infected by coronavirus disease 2019 (COVID-19) in the past 3 years, resulting in 7 million deaths. The virus is primarily transmitted through droplets or aerosols produced by coughing, sneezing, and talking. A full-scale isolation ward in Wuhan Pulmonary Hospital is modeled in this work, and water droplet diffusion is simulated using computational fluid dynamics (CFD). In an isolation ward, a local exhaust ventilation system is intended to avoid cross-infection. The existence of a local exhaust system increases turbulent movement, leading to a complete breakup of the droplet cluster and improved droplet dispersion inside the ward. When the outlet negative pressure is 4.5 Pa, the number of moving droplets in the ward decreases by approximately 30% compared to the original ward. The local exhaust system could minimize the number of droplets evaporated in the ward; however, the formation of aerosols cannot be avoided. Furthermore, 60.83%, 62.04%, 61.03%, 60.22%, 62.97%, and 61.52% of droplets produced through coughing reached patients in six different scenarios. However, the local exhaust ventilation system has no apparent influence on the control of surface contamination. In this study, several suggestions with regards to the optimization of ventilation in wards and scientific evidence are provided to ensure the air quality of hospital isolation wards. [ABSTRACT FROM AUTHOR]

Although diamond seeds are generally polished before growth, the effect of surface roughness of diamond seeds on crystal growth quality is rarely studied. In this research, three diamond seeds were prepared for researching the effect of surface roughness of diamond seed. They were made by cutting a bulk diamond and subsequently suffered partially polished, totally polished and unpolished, respectively. After a period of microwave plasma chemical vapor deposition growth, various tests were carried out on the samples. According to the microscope and step profiler, the surface roughness of diamond seed did not affect the surface roughness of long-term growth diamonds. Compared by Raman spectra, ultraviolet − visible and infra-red spectra, it indicated that a certain rough surface of diamond seed could improve the internal stress of diamond, but reduce the crystalline quality slightly. Moreover, the surface roughness had almost no impact on the optical properties of the diamond. As a result, diamond seeds with low roughness after cutting could be used for direct growth without polishing, bringing on significant economic for gem-quality diamond production. [ABSTRACT FROM AUTHOR]

In the field of machine learning (ML) and data science, it is meaningful to use the advantages of ML to create reliable interatomic potentials. Deep potential molecular dynamics (DEEPMD) are one of the most useful methods to create interatomic potentials. Among ceramic materials, amorphous silicon nitride (SiNx) features good electrical insulation, abrasion resistance, and mechanical strength, which is widely applied in industries. In our work, a neural network potential (NNP) for SiNx was created based on DEEPMD, and the NNP is confirmed to be applicable to the SiNx model. The tensile tests were simulated to compare the mechanical properties of SiNx with different compositions based on the molecular dynamic method coupled with NNP. Among these SiNx, Si3N4 has the largest elastic modulus (E) and yield stress (σs), showing the desired mechanical strength owing to the largest coordination numbers (CN) and radial distribution function (RDF). The RDFs and CNs decrease with the increase of x; meanwhile, E and σs of SiNx decrease when the proportion of Si increases. It can be concluded that the ratio of nitrogen to silicon can reflect the RDFs and CNs in micro level and macro mechanical properties of SiNx to a large extent. [ABSTRACT FROM AUTHOR]

Laser based directed energy deposition (L-DED) is a promising type of additive manufacturing technology. The non-destructive testing technology for the quality monitoring of L-DED processed parts is becoming more and more demanding in terms of accuracy, real-time, and ease of operation. This paper introduces a new image recognition system based on a deep convolutional neural network, which uses multiple lightweight architectures to reduce detection time. In order to eliminate the interference better, it improves the penalty function, which effectively improves the accuracy. Judging from the detection results of the data set, the accuracy of the model training reaches 94.71%, which achieves a very good image segmentation effect and solves the technical problem of in-situ monitoring of the L-DED process. This system realizes the positioning of the spatters for the first time, and at the same time, the number of spatters and area of molten pool are correlated to the laser scanning speed and the laser power. [ABSTRACT FROM AUTHOR]

Metal additive manufacturing (AM) has the advantages of novel part morphology, new material property, and short production cycle, attracting significant attention in automobile, aerospace, and other fields. Nevertheless, the repeatability and stability of part quality are difficult to guarantee in the current metal AM process, hindering the development of metal AM technology. Vital process variables such as molten pool characteristics, spatter characteristics, surface morphology, and radiation temperature are directly related to the quality of parts. Monitoring the dynamic changes vital variables is critical. Image processing techniques such as image transformation, recognition, segmentation, and enhancement are introduced to obtain manufacturing process information through processing and analyzing rich image features. The monitoring system's processing results are usually collected in real time to help solve the repeatability and stability problems of the metal AM process. Presently, in situ and real-time monitoring methods are the most popular, and unfortunately, the literature lacks a comprehensive report. Thus, this paper thoroughly describes in situ and real-time process monitoring on the basis of image processing for metal AM. This paper reviews the in situ and real-time monitoring on the basis of traditional image processing to analyze monitoring objects, process classifications, and image processing carriers. Then, the advantages and disadvantages of in situ and real-time monitoring of metal AM based on artificial intelligence are discussed and compared. Finally, image processing algorithm generalization, quality, small samples, and image labeling problems are analyzed and discussed. A technical route for metal AM real-time feedback control is proposed by combining image processing with other technologies. [ABSTRACT FROM AUTHOR]

Wire bonding is the most popular first-level interconnection technology used in traditional electronic packaging but still needs fundamental research. This work investigated the formation and breakage mechanism of wire-bonding microwelds in typical wire-bonding material pairs by analyzing the loading force curve, total energy curve, atomic morphology, and von Mises stress. The longer the range of the high attractive force of the atoms of a material, the earlier the real contact between the wire and substrate occurs, which means the bonding is completed earlier. The higher stiffness of the material strengthens the weld and causes damage during the bonding process. [ABSTRACT FROM AUTHOR]

Plasma arc additive manufacturing (PAM) is an additive manufacturing technology that has been widely used in the past and has practical applications in many fields. The non-destructive testing methodology of PAM workpiece quality monitoring requires high level of accuracy and real-time capability. The characteristics of the melt pool and plasma arc are the keys to characterizing the dynamic manufacturing process during the powder feed PAM process, allowing for process prediction and real-time feedback control. This paper describes a new image recognition system that uses a fully convolutional network (FCN) to acquire melt pool and plasma arc morphologies simultaneously. Its image segmentation performance is compared with four conventional methods and three artificial intelligence methods. Results show that the FCN method can extract melt pool and plasma arc quickly and accurately, even in a complex manufacturing environment. The image segmentation-based FCN's accuracy is 95.1%, and the average processing time is only 84 ms, according to the results. The performance is far superior to the existing seven methods. The relationship between average captured areas (melt pool and plasma arc) and parameters of the plasma arc (current intensity and scanning speed) is then analyzed. Finally, the quality of products in terms of sample surface roughness is measured, and its relationship with the average areas of the melt pool and plasma arc is clarified. [ABSTRACT FROM AUTHOR]

During the process of growing diamond crystals via microwave plasma chemical vapor deposition (MPCVD), the substrate temperature will gradually increase with increasing growth time. At present, the commonly used method to compensate for the temperature increase is to reduce the deposition parameters (gas pressure and input power) or adjust the height of the susceptor. However, according to previous studies, reducing the substrate parameters will reduce the growth rate. In addition, adjusting the height of the susceptor may cause secondary plasma, which could damage the equipment. Therefore, it is necessary to find the reason for the substrate temperature increase with the growth time and eliminate it. Firstly, the effect of substrate size change on the substrate temperature was simulated dynamically, which indicated that the substrate size change was not the main reason for the continuous increase of the substrate temperature. Subsequent analysis showed that non‐diamond carbon formed at the bottom of the grown diamond, which may cause a change of the thermal contact resistance. Therefore, a thermal contact resistance component was introduced into the existing model of diamond growth, and it was found that the substrate temperature increased with the roughness of the bottom of the substrate. In order to eliminate the influence of thermal contact resistance, a welding growth method was proposed with the aim of avoiding the accumulation of the non‐diamond carbon at the bottom of the substrate. The growth with different welding materials showed that the grown diamond's internal stress distribution after welding growth was similar to that without welding growth, but the non‐diamond carbon at the bottom was obviously restrained. However, the selection of welding materials needs to be further optimized with respect to the welding stability and growth rate. [ABSTRACT FROM AUTHOR]

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Smoking indoors generally exists in daily life, and highlighting the importance of reducing the hazard from smoke particles to non-smoking occupants is crucial. To quantitatively investigate the flow characteristics in a ventilated room, a computational fluid dynamics (CFD) method is used to assess the velocity, concentration, and inhalation levels of indoor particles using a manikin with a realistic upper respiratory tract. It realizes smoke particles' diffusion simulation from room scale to human upper respiratory tract scale. An experiment is also performed to measure PM2.5 concentrations. With the increase of a high air change rate per hour (ACH) from zero to 12.32 and 17.14, the indoor particle concentration reduces by 58.5% and 67.9%, the number of inhaled particles decreases by 22.9% and 43.8%, and the particle concentration around the occupant decreases by 10.3% and 17.5%, respectively. It shows that indoor ventilation has a drastic effect on flow characteristics, particle concentrations, and particle outcomes. ACH of 17.14 is found to significantly reduce the particle concentration around the occupant and decrease the number of smoke particles inhaled and remaining indoors. It indicates that the ventilation equipment can reduce the number of smoke particles in the room. There are still 41.3% and 31.9% particles remaining in the room when the ACH is 12.32 and 17.14, which does harm to human health. [ABSTRACT FROM AUTHOR]

Two-dimensional multiferroics, which simultaneously possess ferroelectricity and magnetism in a single phase, are well-known to possess great potential applications in nanoscale memories and spintronics. On the basis of first-principles calculations, a CrNCl2 monolayer is reported as an intrinsic multiferroic. The CrNCl2 has an antiferromagnetic ground state, with a NĂ©el temperature of about 88 K, and it exhibits an in-plane spontaneous polarization of 200 pC/m. The magnetic moments of CrNCl2 mainly come from the d5 xy orbital of the Cr cation, but the plane of the d xy orbital is perpendicular to the direction of the ferroelectric polarization, which hardly suppresses the occurrence of ferroelectricity. Therefore, the multiferroic exits in the CrNCl2. In addition, like CrNCl2, the CrNBr2 is an intrinsic multiferroic with antiferromagnetic-ferroelectric ground state while CrNI2 is an intrinsic multiferroic with ferromagnetic-ferroelectric ground state. These findings enrich the multiferroics in the two-dimensional system and enable a wide range of applications in nanoscale devices. [ABSTRACT FROM AUTHOR]

Pores in the AlSi10Mg products fabricated by laser powder bed fusion (LPBF) decrease the density of components. To study the mechanism of the formation and evolution of hydrogen pores, a model based on molecular dynamics (MD) is built. The influence of initial hydrogen content, heating time, and cooling time on the porosity is analyzed. Low initial hydrogen content, long cooling time, and appropriate heating time are beneficial to decrease the porosity of LPBF-fabricated products. When the heating time is 40 ps, the cooling time is 200 ps and initial hydrogen content is 0.081%; porosity can be reduced to 3.01%. [ABSTRACT FROM AUTHOR]

The nitrogen-vacancy (NV) center is a point defect in the diamond, which can be used as a quantum sensor or emitter. It must maintain a negative charge state to utilize its electronic and optical properties. However, enhancing the negative charge stability and avoiding becoming the "dark state" have been challenges in many situations. In this study, we introduced phosphorus atoms as donor elements to provide extra electrons to the NV center to keep its negative charge state through theoretical simulation. We used density functional theory to investigate the electronic and optical properties of the NV center with phosphorus donors in different configurations. We confirmed that the NV center with phosphorus donor could retain its original properties required as a quantum bit. Moreover, in the non-local excitation processes, both in the one-photon and two-photon approaches, including the intersystem crossing (ISC) process, the NV center with phosphorus donor could have a higher resistance to charge conversion (from NV− to NV0) and the "photo-blinking" phenomenon than the NV center with nitrogen donor. Thus, our results suggest that phosphorus can be a promising donor element for improving the stability and functionality of the NV center in quantum applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Surface functionalization of diamonds is an important topic for the negatively charged nitrogen-vacancy (NV−) center based quantum sensors. We investigate the electronic properties of oxidized diamond (111) surfaces and their effects on the NV− centers using the density of functional theory. The results show that the epoxy oxidized diamond (111) surface has neither surface spin noises nor inter-bandgap states and also has a positive electron affinity (1.85 eV) with nearly 99% preferential alignment of nitrogen-vacancy, indicating the epoxy oxidized (111) surface could be a perfect host of the NV− centers. Additionally, we make further examinations by placing an NV− center ∼1 nm from the epoxy oxidized (111) surface. The results indicate that the epoxy oxidized (111) surface has no obvious effects on the defect levels and optical transitions of the single NV− center. To the best our knowledge, the epoxy oxidized (111)-(2 × 1) surface may be the first diamond surface that not only theoretically satisfies the electronic requirements of shallow NV− centers but can also be fabricated through the oxidization process. Therefore, the epoxy oxidized diamond (111)-(2 × 1) surface is the most promising candidate to be applied in NV-based quantum sensors. Image 1 [ABSTRACT FROM AUTHOR]

Phosphorus is regarded as the best substitutional donor for n-type diamonds. However, because of vacancy-related complexes, H-related complexes, and other defects in P-doped diamonds, obtaining n-type diamonds with satisfying properties is challenging. In this report, PV and PVH complexes are studied in detail using density function theory (DFT). The formation energy reveals the possibility of emergency of these complexes when doping a single P atom. Although vacancies have difficulty forming on the surface alone, the presence of P atoms benefits the formation of PV and PVH complexes and significantly increases crystal vacancies, especially in (111) diamond surfaces. Compared to (111) surfaces, PV and PVH complexes more easily form on (001) surfaces. However, the formation energies of these complexes on (001) surfaces are higher than those of doping P atoms. Studying the structural deformation demonstrated that both constraints of the upper and lower C layers and forces caused by structural deformation prevented doping P atoms. By analyzing the bond population around these dopants, it finds that the bond populations of P–C bonds of PVH complexes are larger than those of PV complexes, indicating that the PV complexes are not as stable as the PVH complexes. [ABSTRACT FROM AUTHOR]

Fibrous filters, which are the most commonly used means of particle filtration, are generally characterized by the air pressure drop and filtration efficiency. The nature of particle movement and interaction between the particle and fibre is of great importance for measuring the filtration efficiency of fibrous filters. Majority of previous studies investigated particle trajectory and deposition using the ideal trapping model, which assumed that particles will be trapped once contacted with a solid surface (fibre or deposited particle). This work investigates the dynamic performance of particle rebound and statistically analyses the deposition/accumulation of particles on a fibre surface. We use the computational fluid dynamics (CFD) method to calculate the flow field around a row of fibres. Then, we utilize a particle adherence and rebound criterion and simulate the particle trajectory and deposition using a self-developed solver in Fortran code. Effects of face velocity, particle diameter, and particle rebound characteristics on particle rebound and accumulation around one of the fibres are investigated. Additionally, the trajectories and accumulation of particles on the fibre surface are visually presented. Finally, the filtration efficiency of a single fibre is compared with published results. It is found that effects of particle rebound on the particle trajectory and deposition are significantly related to the face velocity and particle diameter. With considering the particle rebound, the filtration efficiency of a single fibre is obviously different from that of previous studies. [ABSTRACT FROM AUTHOR]

Featured Application: This paper presents the in-situ laser polishing of four typical alloys in the selective laser melting (SLM) process. Selective laser melting (SLM) is a layer by layer process of melting and solidifying of metal powders. The surface quality of the previous layer directly affects the uniformity of the next layer. If the surface roughness value of the previous layer is large, there is the possibility of not being able to complete the layering process such that the entire process has to be abandoned. At least, it may result in long term durability problem and the inhomogeneity, may even make the processed structure not be able to be predicted. In the present study, the ability of a fiber laser to in-situ polish the rough surfaces of four typical additive-manufactured alloys, namely, Ti6Al4V, AlSi10Mg, 316L and IN718 was demonstrated. The results revealed that the surface roughness of the as-received alloys could be reduced to about 3 μm through the application of the laser-polishing process, and the initial surfaces had roughness values of 8.80–16.64 μm. Meanwhile, for a given energy density, a higher laser power produced a laser-polishing effect that was often more obvious, with the surface roughness decreasing with an increase in the laser power. Further, the polishing strategy will be optimized by simulation in our following study. [ABSTRACT FROM AUTHOR]

Featured Application: This paper presents a laser ultrasonic testing (LUT) method for the inspection of internal hole defects in a Ti-6Al-4V part produced by additive manufacturing (AM). The LUT system achieved a resolution in sub-millimeter scale, demonstrating its significant potential in the quality evaluation of additive manufactured part. For a non-contact, non-destructive quality evaluation, laser ultrasonic testing (LUT) has received increasing attention in complex manufacturing processes, such as additive manufacturing (AM). This work assessed the LUT method for the inspection of internal hole defects in additive manufactured Ti-6Al-4V part. A Q-switched pulsed laser was utilized to generate ultrasound waves on the top surface of a Ti-6Al-4V alloy part, and a laser Doppler vibrometer (LDV) was utilized to detect the ultrasound waves. Sub-millimeter (0.8 mm diameter) internal hole defect was successfully detected by using the established LUT system in pulse-echo mode. The method achieved a relatively high resolution, suggesting significant application prospects in the non-destructive evaluation of AM part. The relationship between the diameter of the hole defects and the amplitude of the laser-generated Rayleigh waves was studied. X-ray computed tomography (XCT) was conducted to validate the results obtained from the LUT system. [ABSTRACT FROM AUTHOR]

Single neutral silicon-vacancy ( SiV 0 ) color centers under H-, O-, or N-terminated diamond (001) surfaces were investigated using density functional theory. The formation energy calculation indicated that it is generally easier for SiV 0 to be embedded in an O-terminated diamond (001) surface as compared with H- and N-terminated surfaces, which were effected above the fifth C layer. The effects of the surface termination species on inner diamond atoms decay to be negligible below the fifth C layer. The binding energy results indicated that SiV centers exhibited rather high energetic stability once formed. Additionally, it was revealed that these three surface-terminating species had contracting or expanding effects on inner surface atoms. The calculation for density of states showed that the N-terminated diamond (001) surface served as a suitable medium for single SiV 0 to function as a single-photon source. [ABSTRACT FROM AUTHOR]

Background and Purpose: Skeletal muscle is the predominant site for glucose disposal and fatty acid consumption. Emerging evidence indicates that the crosstalk between adipose tissue and skeletal muscle is critical in maintaining insulin sensitivity and lipid homeostasis. The current study was designed to investigate whether myricanol improves insulin sensitivity and alleviates adiposity through modulating skeletal muscle-adipose tissue crosstalk.Experimental Approach: The therapeutic effect of myricanol was evaluated on palmitic acid (PA)-treated C2C12 myotubes and high-fat diet (HFD)-fed mice. The crosstalk between myotubes and adipocytes was evaluated using Transwell assay. The cellular lipid content was examined by Nile red staining. The mitochondrial content was assessed by MitoTracker Green staining and citrate synthase activity, and the mitochondrial function was examined by Seahorse assay. Expression of mitochondria-related and insulin signalling pathway proteins was analysed by Western blot, and the irisin level was determined by elisa kit.Key Results: Myricanol increased mitochondrial quantity and function through activating AMP-activated protein kinase, resulting in reduced lipid accumulation and enhanced insulin-stimulated glucose uptake, in PA-treated C2C12 myotubes. Furthermore, myricanol stimulated irisin production and secretion from myotubes to reduce lipid content in 3T3-L1 adipocytes. In HFD-fed mice, myricanol treatment alleviated adiposity and insulin resistance through enhancing lipid utilization and irisin production in skeletal muscle and inducing browning of inguinal fat.Conclusions and Implications: Myricanol modulates skeletal muscle-adipose tissue crosstalk, to stimulate browning of adipose tissue and improve insulin sensitivity in skeletal muscle. Myricanol might be a potential candidate for treating insulin resistance and obesity. [ABSTRACT FROM AUTHOR]

Boron-terminated bare and oxidized diamond (001) surfaces are first proposed in this paper and are modelled by adsorbing the boron (B) atoms onto the bare and oxidized diamond (001) surfaces, respectively. The electron affinities (EAs) and adsorption energies per B atom of the B-terminated bare and oxidized diamond (001) surfaces were investigated via density functional theory calculations. Applying 1 monolayer (ML) B coverage yields a more negative EA (NEA) than 0.25 ML or 0.5 ML coverage on the bare diamond surfaces, and a larger positive EA (PEA) on the oxidized diamond surfaces. Their positive adsorption energies mean that 1 ML B coverage is energetically favorable on both the bare and oxidized diamond (001) surfaces. The B-terminated bare diamond (001) surfaces with 1 ML coverage have an NEA of up to −1.39 eV, and their adsorption energy is higher than that of hydrogen-terminated diamond (001) surfaces by 1.49 eV, thus they could potentially be applied to create thermally stable electron emission devices. The B-terminated oxidized diamond (001) surfaces (1 ML coverage) have a PEA of up to 3.21 eV, larger than the EAs of ether oxidized (2.39 eV), nitrogen-terminated (3.01 eV), or fluorine-terminated (2.34 eV) diamond (001) surfaces. Consequently, the B-terminated oxidized diamond (001) surfaces show great potential for NV and SiV quantum sensing applications. [ABSTRACT FROM AUTHOR]

Selective laser melting (SLM) produces complex physical behaviors. After laser melting, the molten pool condenses with an uneven surface, which influences the next powder spreading process and affects the quality of the final product. This phenomenon is mainly caused by the Marangoni effect, which is generated by the surface tension of the liquid. This paper describes a method to control the surface deformation during the SLM of AlSi10Mg powder. It is assumed that there is a magnetic field (MF) added to the alloy powder generating a Lorentz force in the molten pool (MP). The Lorentz force can decrease the impact of the Marangoni effect and change the velocity field. Our work simulates the AlSi10Mg alloy melting process, and analyzes the physical parameters of the MP with or without an MF. It is found that increasing the MF within a certain range decreases the impact of the Marangoni effect, resulting in a smoother surface. [ABSTRACT FROM AUTHOR]

Background: Muscle atrophy and weakness are adverse effects of high dose or the sustained usage of glucocorticoids. Loss of mitochondria and degradation of protein are highly correlated with muscle dysfunction. The deacetylase sirtuin 1 (SIRT1) plays a vital role in muscle remodelling. The current study was designed to identify myricanol as a SIRT1 activator, which could protect skeletal muscle against dexamethasone‐induced wasting. Methods: The dexamethasone‐induced atrophy in C2C12 myotubes was evaluated by expression of myosin heavy chain, muscle atrophy F‐box (atrogin‐1), and muscle ring finger 1 (MuRF1), using western blots. The mitochondrial content and oxygen consumption were assessed by MitoTracker staining and extracellular flux analysis, respectively. Muscle dysfunction was established in male C57BL/6 mice (8–10 weeks old, n = 6) treated with a relatively high dose of dexamethasone (25 mg/kg body weight, i.p., 10 days). Body weight, grip strength, forced swimming capacity, muscle weight, and muscle histology were assessed. The expression of proteolysis‐related, autophagy‐related, apoptosis‐related, and mitochondria‐related proteins was analysed by western blots or immunoprecipitation. Results: Myricanol (10 μM) was found to rescue dexamethasone‐induced muscle atrophy and dysfunction in C2C12 myotubes, indicated by increased expression of myosin heavy chain (0.33 ± 0.14 vs. 0.89 ± 0.21, *P < 0.05), decreased expression of atrogin‐1 (2.31 ± 0.67 vs. 1.53 ± 0.25, *P < 0.05) and MuRF1 (1.55 ± 0.08 vs. 0.99 ± 0.12, **P < 0.01), and elevated ATP production (3.83 ± 0.46 vs. 5.84 ± 0.79 nM/mg protein, **P < 0.01), mitochondrial content (68.12 ± 10.07% vs. 116.38 ± 5.12%, *P < 0.05), and mitochondrial oxygen consumption (166.59 ± 22.89 vs. 223.77 ± 22.59 pmol/min, **P < 0.01). Myricanol directly binds and activates SIRT1, with binding energy of −5.87 kcal/mol. Through activating SIRT1 deacetylation, myricanol inhibits forkhead box O 3a transcriptional activity to reduce protein degradation, induces autophagy to enhance degraded protein clearance, and increases peroxisome proliferator‐activated receptor γ coactivator‐1α activity to promote mitochondrial biogenesis. In dexamethasone‐induced muscle wasting C57BL/6 mice, 5 mg/kg myricanol treatment reduces the loss of muscle mass; the percentages of quadriceps and gastrocnemius muscle in myricanol‐treated mice are 1.36 ± 0.02% and 0.87 ± 0.08%, respectively (cf. 1.18 ± 0.06% and 0.78 ± 0.05% in dexamethasone‐treated mice, respectively). Myricanol also rescues dexamethasone‐induced muscle weakness, indicated by improved grip strength (70.90 ± 4.59 vs. 120.58 ± 7.93 g, **P < 0.01) and prolonged swimming exhaustive time (48.80 ± 11.43 vs. 83.75 ± 15.19 s, **P < 0.01). Myricanol prevents dexamethasone‐induced muscle atrophy and weakness by activating SIRT1, to reduce muscle protein degradation, enhance autophagy, and promote mitochondrial biogenesis and function in mice. Conclusions: Myricanol ameliorates dexamethasone‐induced skeletal muscle wasting by activating SIRT1, which might be developed as a therapeutic agent for treatment of muscle atrophy and weakness. [ABSTRACT FROM AUTHOR]

Highlights • P–H complex has the lowest energy when H occupies the AB site. • P–H complex is most stable when P is doped within the second C layers. • P–H complex is less likely to form in (1 1 1) surface than in (0 0 1) surface. Abstract Although phosphorus is an n-type donor in diamond, H impurities can bind to and passivate P. Here, H binding to a P dopant in both diamond (0 0 1) and (1 1 1) surfaces is investigated by density functional theory. The energy calculations reveal the most stable P–H complex structures for each P-doped position. P–H binding energies are the lowest for the second P doped C layer among those for four investigated P-doped C layers. H migration from on-surface to P in the second C layer is exothermic, with an energy barrier of zero, whereas that from on-surface to P below the second C layer is endothermic, with an energy barrier greater than 0.95–7.09 eV. Thus, both of binding energy and migration calculations imply that P–H complex is more likely to form when P is doped in the second C layer than when P is doped below the second C layer. Moreover, H migration energy barrier from on-surface to P below the second C layer in the (1 1 1) surface is at least 0.85 eV greater than that in the (0 0 1) surface, which indicates that P–H complex is less likely to form in (1 1 1) surface than in (0 0 1) surface. [ABSTRACT FROM AUTHOR]

Highlights • Myricanol from the barks of Chinese bayberry was identified as an AMPK activator. • Myricanol inhibited adipogenesis in the initial stage of adipocytes differentiation. • Myricanol induced lipolysis and lipid oxidation in 3T3-L1 adipocytes. • Myricanol improved insulin sensitivity in mature adipocytes. • Myricanol attenuated lipid accumulation in high-fat diet-fed zebrafish. Abstract Myricanol is a diarylheptanoid isolated from Chinese bayberry. Through virtual docking strategy, myricanol was discovered as an AMP-activated protein kinase (AMPK) activator among a series of structural analogs, with high affinity for the γ subunit of AMPK. Myricanol was also evaluated for regulatory effects on lipid accumulation and insulin sensitivity in 3T3-L1 adipocytes and adiposity in high-fat diet-fed zebrafish. Myricanol suppressed lipid accumulation in 3T3-L1 cells in the initial stage (days 0–2) by suppressing adipogenesis and in the terminal stage (days 4–7) by inducing lipolysis and lipid combustion through activating AMPK. Moreover, myricanol enhanced insulin-stimulated glucose uptake by activating the insulin signaling pathway. In high-fat diet-fed zebrafish, myricanol inhibited lipid accumulation by suppressing adipogenic factors including peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT/enhancer binding protein α (C/EBPα). In summary, the results indicate that myricanol could be a potential therapeutic agent against obesity by activating the AMPK signaling pathway. [ABSTRACT FROM AUTHOR]

Particle intrusion into the head–disk interface (HDI) is becoming a concern in hard disk drives. Numerical studies of particle movement in HDI are of great importance for reducing particle-induced damage. In this investigation, we study the particle rebound mechanism in HDI. Not only the particle–slider collision but also particle–particle collision models are developed, which are divided into three types, including the collisions of particle and surface (P–S), particle and edge (P–E), and particle and particle (P–P). The subsequent response of particles after the collision, which includes rebound and adhesion, is calculated considering the collisional energy loss. The proposed adhesion/rebound model can more accurately present the particle trajectories in HDI and accumulation on the air bearing surface (ABS). We find that particles are likely to accumulate on the leading rail surfaces of the slider due to the air flow drag and Saffman lift. Considering the adhesion and rebound, particles with a larger diameter are more likely to fly away from the slider after the collision. The existence of particle rebound, to a certain degree, reduces contamination on ABS. [ABSTRACT FROM AUTHOR]

Heat-assisted magnetic recording (HAMR) technology is a great way to achieve higher storage density. In HAMR, dynamic performance of the head–disk interface (HDI) is critically important for the read/write stability. Lubricant bridge formation and lubricant transfer can significantly deteriorate HDI performance. In this paper, a 3-D full-atom model of a slider-lubricant-disk substrate system is established to study the dynamic performance of HDI in HAMR. The overlayers of the slider and disk substrate are made of diamondlike carbon, and the main lubricating ingredient is perfluoropolyether (PFPE). The formation and breaking of the lubricant bridge are investigated with the slider moving up and down. It is found that during the moving down process, PFPE molecules escape from the lubricant layer, and a lubricant bridge between the slider and disk is formed. During the moving up process, the lubricant bridge becomes thin and eventually breaks. The stable value of PFPE weight percentage on the slider during the moving up process is always larger than that during the moving down process. This is because of easier transfer of lubricant molecules to the slider in the low flying height region. The formation height is smaller than the breaking height, but these values are closer when the operational temperature is higher. [ABSTRACT FROM AUTHOR]

The lateral flow in hard disk drives is greatly disturbed because of the arm swinging rapidly during track seeking, which can greatly affect off-track residual vibrations during track following of the head-gimbal assembly (HGA), as well as the slider. Until now, no simulation studies have been performed to investigate off-track residual vibrations of the HGA that consider lateral flow effects. In this paper, the effect of track-seeking on off-track residual vibrations of the HGA is investigated for air and helium environments using the so-called “fluid dynamic mesh” and the “fluid-structure interaction” methods for the first time. Three different angular acceleration profiles (a square wave, a triangular wave, and a sinusoidal wave) are investigated as a function of seek time (10 and 5 ms). Results show that the smoothening of sharp transitions in the seek profile improves the performance of off-track residual vibrations and shortens the track-following time of the head positioning servo system. In addition, the effect of lateral flow (windage) on off-track residual vibrations must be considered for a square-wave angular acceleration profile. Simulation results show that helium improves the track-following accuracy compared to air because of the lower windage forces acting on the HGA. We observe that the sinusoidal-wave angular acceleration performs best for the three angular acceleration profiles investigated. Furthermore, seek time is found to have only a small effect on off-track residual vibrations during track following. [ABSTRACT FROM PUBLISHER]

Filtering Facepiece Respirator (FFR) is the most common respirator users in the health care environment utilize for personal protection from outside particles. Comfort and fit are important while wearing an FFR. This paper proposes a novel technology to produce customized face seal design for improving the wearing comfort and fit of FFR wearers. In order to customize the design of face seals, we scanned the faces of three subjects using three-dimensional (3D) laser scanning method. A customized face seal for a 3M 8210 N95 FFR for each headform was designed using reverse engineering technique. Next, the face seal prototypes were fabricated with Acrylonitrile Butadiene Styrene (ABS) plastic using the 3D printing method. A force sensing system based on Arduino Uno R3 was developed, and the force sensor of this system was inserted between the FFR and headform to measure contact pressure. Experimental results showed that the newly designed FFR face seal provided the subjects with an improved contact pressure. [ABSTRACT FROM AUTHOR]

The technology of heat-assisted magnetic recording (HAMR) has improved the storage density of hard disc drives. The PFPE molecules of lubricant layer adhered on the disc can transfer from the lubricant layer and form the lubricant bridge which can deteriorate the stability of read/write process. In this paper, the formation and breaking of lubricant bridge at the head–disc interface (HDI) affects HAMR stability and deserves to be investigated. Using molecular dynamic simulation, a full-atom model was built to evaluate the behaviour of the lubricant bridge. Moreover, the effects of lubricant temperature, heating-up time, disc rotation speed and bearing pressure on the HDI were studied. It has been found that the amount of transferring atoms sharply increased when the lubricant temperature was above 700 K. The loss rate of lubricant layer decreased gradually during the heating process and it took about 2.2 ns for the remaining lubricant to reach stability. Furthermore, transferring PFPE molecules can form the lubricant bridge. A shorter heating-up time makes the lubricant bridge thicker and more robust. And the duration of lubricant bridge is notably affected by heating-up time, rotation speed and bearing pressure. A shorter heating-up time leads to a longer duration of lubricant bridge, whereas a higher rotation speed and bearing pressure reduces the duration of lubricant bridge. [ABSTRACT FROM PUBLISHER]

The presence of particles, which can intrude into the gas bearing, is one of the most common factors in the failure of hard disk drives (HDDs). Previous works investigated particle trajectories inside air-filled drives without considering temperature effects on the distribution of particles. Actually, especially for the submicron particle, particle trajectories and trapping status are affected by the temperature gradient since the thermophoretic force cannot be ignored. In this paper, considering major heat generation components such as the spindle motor and voice coil motor (VCM), trajectories and trapping status for AlO particles inside a 2.5 inch helium-filled drive are simulated by the commercial computational fluid dynamics solver FLUENT with user-defined functions (UDFs). The trapping criterion for AlO particles is used as boundary conditions for different colliding surfaces. The results reveal that particles in the air-filled drive will more likely degrade the head-disk interface (HDI) reliability. In addition, after considering the temperature, the particle trapping rate by the disk decreases both inside the air-filled drive and the helium-filled drive. And its reduction inside the air-filled drive is larger. Moreover, small particles will more likely degrade the HDI reliability since they can follow the rotatory flow well and have more chance to collide with the disk surface, and then easily attach onto the disk surface. [ABSTRACT FROM AUTHOR]

An entrapped particle on the slider's air bearing damages the surface of the slider or the disk. The study of particle movement on and the particle adhesion mechanism onto the slider surface is critical to reduce entrapped particle-induced damage. In this paper, we proposed a dynamical model of the adhesive particle's secondary migration on the slider surface. The model predicts whether the adhered particle will remain static by the action of the aerodynamic and adhesion forces. There are three migration movement styles which are rolling, sliding and lifting away from the original adhered location. Further, particle rolling migration behaviors on the slider air bearing surface (ABS) are analyzed considering the effects of flow shear rate, particle diameter and properties. Finally, the particle migration trajectory and velocity with time on the investigated slider are presented. It was found that most particles that adhere to the slider surface remain static for the investigated slider; pure rolling motion on the slider ABS is the main migration styles. The particle with a larger diameter and air shear rate speeds up to a higher velocity, and it takes more time to speed up to the constant velocity. A particle's secondary migration motion can be observed for the particle that adheres to the slider recession region and trailing pad. Then the particle enters airflow blowing out of or rolls away from the head-disk interface. [ABSTRACT FROM AUTHOR]

This study investigated the effect of four typical facial expressions (calmness, happiness, sadness and surprise) on contact characteristics between an N95 filtering facepiece respirator and a headform. The respirator model comprised two layers (an inner layer and an outer layer) and a nose clip. The headform model was comprised of a skin layer, a fatty tissue layer embedded with eight muscles, and a skull layer. Four typical facial expressions were generated by the coordinated contraction of four facial muscles. After that, the distribution of the contact pressure on the headform, as well as the contact area, were calculated. Results demonstrated that the nasal clip could help make the respirator move closer to the nose bridge while causing facial discomfort. Moreover, contact areas varied with different facial expressions, and facial expressions significantly altered contact pressures at different key areas, which may result in leakage. [ABSTRACT FROM AUTHOR]

Currently, heat-assisted magnetic recording (HAMR) technology has been proposed as a method for enabling higher storage density. In this paper, the molecular dynamic simulation method was used to investigate the consumption and recovery of the lubricant perfluoropolyether (PFPE) layer under rapid heating and cooling through HAMR. A full-atom model for the 3-D slider-lubricants-disk substrate system was built for this paper. The lubricant adheres to the diamond-like carbon substrate, and the space between the slider and the lubricant is filled with helium atoms. It is found that HAMR laser heating results in the gradual consumption of the PFPE lubricant, and that the target operational temperature T0 significantly affects the consumption of the PFPE lubricant on the disk substrate. The extent of lubricant consumption increases sharply when T0 is above 600 K. The lubricant’s weight percentage on the disk substrate rises up again when cooling occurs. But it cannot be completely recovered. On the other hand, the bearing pressure reduces the degree of consumption of the PFPE lubricant by laser heating. However, the effect of bearing pressure on the amount of remaining PFPE lubricant becomes weak when T0 is above 800 K. [ABSTRACT FROM AUTHOR]

The lubricant bridge connecting the slider and the disk will significantly deteriorate the read–write stability of the hard disk drive. This paper builds a model of disk-lubricant-slider system. The coarse-grained bead-spring model is used to represent perfluoropolyethers molecules. And the molecular dynamic method is used to study the formation time and the molecule number of the lubricant bridge under different disk rotation speeds and slider flying heights. Furthermore, the influence of lubricant bridge on the pressure acting on the slider pad is also studied. [ABSTRACT FROM AUTHOR]

Previous works investigated particle trajectories in hard disk drives (HDDs) with the actuator arm and the head gimbals assembly at a fixed position. Actually, internal fluid field characteristics of HDDs can be greatly changed by the arm swing during track-seeking operations, which can affect particle trajectories and trapping status. In this paper, using the dynamic mesh method in a 2.5 in HDD for the first time considers the arm swing in the computational fluid dynamics (CFD) simulation. Al2O3 particle trajectories in this HDD are studied by the CFD solver FLUENT with user-defined functions. The trapping criterion for Al2O3 particles is used as a boundary condition for colliding surfaces. Simulation results reveal that the particle undergoes a larger number of collisions with the disk surface for the average seek time of 12 ms than for the average seek time of 6 ms. In addition, the faster the arm swings, the larger the number of particles that gather near the arm, and the shorter time it will take for particles to be trapped. Moreover, particle-surface collisions can successively take place many times in the helium flow. Furthermore, the particles are trapped slower in the helium-filled drive than in the air-filled drive. [ABSTRACT FROM AUTHOR]

Heat-assisted magnetic recording (HAMR) is a new approach, which makes the head write data easily under a low magnetic field using a laser to heat the magnetic media to reduce its coercivity, thus, it is considered to be the next generation of higher recording areal density technology. In this paper, a three-dimensional HAMR finite-element model of hard disk drive (HDD) is developed. The temperature distributions around the laser-heating area on disk surface are investigated when the HDD is filled with air and helium. The cooling effects of the disk rotation and the heat convection in head-disk interface (HDI) are also analyzed. [ABSTRACT FROM AUTHOR]

A numerical method is presented to study the air-flow pattern and particle trajectory in the head–disk interface (HDI) in this paper. It first solves the generalized steady-state Reynolds equation with slip boundary conditions to get the slider attitude. Then, it solves the reduced Navier–Stokes equation to get the air flow velocity distribution in the HDI. The motion equations of particles are solved to obtain the particle trajectory in the HDI by using the fourth-order Runge–Kutta method. Air flow characteristics and particle behaviors are investigated to illustrate the relationship between the air flow and particle trajectory. The effect of the particle release height is also studied. The simulation results show that particle trajectories basically overlap air flow streamlines in the horizontal plane. The particle moves a longer horizontal distance at a lower particle release height. The difference between the horizontal velocity of the particle and the air flow indicates that the Saffman force points to the disk in the transition region close to the leading edges of leading pads. Moreover, the peak values of the air flow vertical velocity in the previously mention location increase with the reduction of the particle release height. And the air flow vertical velocity along the particle trajectory is almost two times larger than that of the particle at the leading edges of leading pads. The results also show that the drag force of the air flow mainly drives particles up toward the air bearing surface at the leading edges of leading pads, but not the Saffman force. [ABSTRACT FROM PUBLISHER]