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The frequency domain analysis (FDA) offers greater computational efficiency than the method of characteristic (MOC) in simulating transient flow in pressurized pipes. However, its accuracy is hindered by linearisation errors. Violations of the assumptions for linearisation in friction term and valve equations during water distribution systems (WDSs) burst simulations make the FDA results meaningless. Linearisation procedures are modified as follows using the Heaviside property of pipeline bursts to address this problem: (1) the linearization of the friction term is adjusted, and (2) the valve equation is approximated using a three-step approach. The higher-order term dropped by the original FDA is linearly approximated to achieve better accuracy. The modified FDA is compared to the MOC in a real-life WDS by numerical experiment. Excellent precision can be observed even for a highly nonlinear case where the burst flow is 20% of the initial total demand. The simulation time is significantly shorter than when using the MOC. The proposed modification dramatically improves the applicability of the FDA for solving the nonlinear error issue during the simulation of the pipeline burst. This result implies the potential for its application in quick inverse analysis of pipeline bursts. [ABSTRACT FROM AUTHOR]

For identifying and classifying surface defects of strip steel in industrial production and improving the efficiency of defect detection, a detection and recognition system for surface quality defects of strip steel in industrial production environments is designed in this article. Firstly, industrial raw material strip steel was used as the research object, and an experimental operating environment was established to label the dataset. Then, entered into the image, image scaled by YOLOv5s, and then the image is scaled into S × S using convolutional neural networks. Feature maps are extracted from each small grid. Secondly, the extracted feature maps were pooled and subjected to a series of sharding, stitching, and multi-scale feature fusion. Finally, under the GPU acceleration of the PyTorch learning framework, the processing speed was improved by identifying categories through a fully connected layer network, all indicators have been detected, as well as information on the category and confidence level of defects identified. The experimental results show that the system can identify four types of defects on the surface of the strip steel and achieve an accuracy of 90% in identifying defect types. [ABSTRACT FROM AUTHOR]

The finite element numerical calculation can get the shock wave velocity and overpressure at any point in the explosion field, but some factors such as the parameter value of the state equation influence the calculation results. The tomography inversion can acquire the velocity and overpressure distribution of shock wave; however, the initial model and constraints can affect the inversion results. Aiming at the shortcoming of the two algorithms, this article combines the two methods and presents a new algorithm to reconstruct the explosion field. First, The LS-DYNA finite element program is applied to establish a numerical model and calculate the shock wave velocity and superpressure in air explosion. Second, generalized inversion with regularization tomography inversion algorithm is used to invert the shock wave field. In the inversion, the finite element calculation results are used as the initial model of inversion and constrain the inversion. The experiment results prove that the proposed algorithm can greatly improve the inversion accuracy and the iterative convergence speed. The inversion image can better depict the internal details of the explosion field and eliminate noise. [ABSTRACT FROM AUTHOR]

The spindle system is important in the machine tool. The vibration signal generated by the spindle system in the machine tool has a great influence on the machining accuracy of the product and the abrasion and lifetime of the tool. Therefore, it is necessary to monitor the vibration signal in the machining process of the machine tool spindle in real time. The vibration sensor is used to monitor the vibration signal of the machine tool spindle in this paper. The data collected by the sensors are transmitted to the Bluetooth module by the serial port for wireless communication. The vibration signal and its frequency domain transformation of the spindle are received by LabVIEW software platform, and the original waveform is displayed, the threshold alarm and the storage of data are realized. The experimental results show that the designed system can realize the online monitoring of the vibration state of the machine tool spindle effectively. [ABSTRACT FROM AUTHOR]

Molybdenum disulfide (MoS2) has excellent photothermal conversion abilities, an ultra-high specific surface area, and has been extensively explored for use in biomedicine. However, the high toxicity associated with MoS2 has limited its biological applications for in vivo photothermal therapy and drug delivery systems. Herein, we have developed cationic hydroxyethyl cellulose (JR400) surface-modified MoS2 nanoparticles (NPs) that are responsive to near-infrared (NIR) laser irradiation as a transdermal drug delivery system (TDDS). Herein, we confirmed the preparation of hexagonal phase MoS2 with robust surface modification with JR400. The flower-like morphology of the NPs had an average diameter of 355 ± 69.3 nm limiting the absorption of the NPs through the stratum corneum. With the ability to efficiently load 90.4 ± 0.3% of the model drug atenolol (ATE), where 1 g of JR400-MoS2 NPs was able to load 3.6 g ATE, we assayed the controlled release capacity in vitro skin penetration studies. These JR400-MoS2 NPs showed further enhancement under NIR stimulation, with a 2.3-fold increase in ATE skin penetration. Furthermore, we verified in vivo that these JR400-MoS2 NPs do not cause skin irritation suggesting that they are promising new TDDS candidates for small molecule drugs. [ABSTRACT FROM AUTHOR]

The flow and heat transfer characteristics of a droplet obliquely impact on a stationary liquid film is numerically studied by using a coupled level set and volume of fluid method (CLSVOF). The effects of impact angle, Weber number, and film thickness are analyzed. As compared with the normal impact, the flow features and surface heat flux distribution for oblique impact are asymmetric and where the secondary droplets only can be observed on one side. Corresponding mechanisms have also been interpreted. The maximum value of the local surface heat flux decreases and moves to the right with the increase in impact angle, while the minimum local surface heat flux on both sides increases as the impact angle increases. With a greater Weber number or a thinner film thickness, the maximum local surface heat flux is higher, while the minimum local surface heat flux on both sides appears to be an opposite trend. In addition, the impact angle has little effect on the average surface heat flux. [ABSTRACT FROM AUTHOR]

To better understand the droplet impact on the liquid film with vapor bubbles in spray cooling, a two-dimensional symmetric numerical model is set up using the Coupled Level Set and Volume of Fluid method (CLSVOF). Three simulative cases are taken, considering the effects of film thickness and the presence of vapor bubbles or not. The main purposes of this paper are to investigate the evolution of vapor bubbles during droplet impact and to identify the effect of vapor bubbles on convection heat transfer. The results indicate that vapor bubbles will detach from the wall and break up at the surface of the liquid film during droplet impact, for a thinner film, later a "sawtooth" liquid film appears at the non-impact region. However, for a thicker film, no bubbles rupture and the detached bubbles will flow inside the liquid film and then some will merge into larger bubbles. In the presence of vapor bubbles, the crater radius is larger for a thicker liquid film. The presence of vapor bubbles will facilitate the subcooled droplet to spread to the heated wall, leading to a substantial increase in surface heat flux. [ABSTRACT FROM AUTHOR]

1,4-Butanediol (BDO) biosynthesis from renewable resources is of increasing interest because of global energy and environmental problems. We have previously demonstrated the production of BDO from erythritol by whole-cell catalysis. Here, the effects of several variables on BDO production were investigated, including cell density, temperature, substrate concentration and pH. It was found that the maximum BDO production was obtained at cell density (OD600) of 30. Low temperature and weak alkaline environment were beneficial for the biotransformation. Regarding substrate concentration, 80 g/L of erythritol was found to be optimum for the bioconversion. Under the optimal conditions, the highest concentration of BDO reached 34.5 mg/L, resulting in 5.8-fold increment after optimization. These results will provide useful guidance for enhancing the bioconversion of erythritol to BDO. [ABSTRACT FROM AUTHOR]

A two-dimensional incompressible laminar computational model was established to analyze flow and heat transfer characteristics during a single liquid drop impinging onto a liquid film, with an underneath surface of relatively low temperature. Using the coupled level set and volume of fluid method, the gas–liquid interface at different time sequences can be obtained clearly. Concerning the heat transfer process, three different factors including impact velocity, film thickness, and drop diameter were discussed. Results indicate that liquid inside the film can be classified as three zones: the impact zone, the transition zone, and the static zone, specifically according to different heat flux. Average surface heat flux can be increased by increasing impact velocity, while effects of film thickness and drop diameter are minor. Corresponding mechanisms were interpreted as well. For heat flux distribution in the impact and transition zones, both film thickness and drop diameter influence the distribution greatly. With an increment in film thickness and drop diameter, heat flux in the impact zone decreases, while heat flux in the transition zone appears to be an opposite trend. Also in the transition zone, the fluctuation amplitude of the heat flux rises as the two factors are reduced. [ABSTRACT FROM PUBLISHER]

A single drop impact on a liquid film is numerically investigated using the coupled level set and volume of fluid (CLSVOF) method. Influences of gas properties including gas density and viscosity on the crown liquid sheet behavior and the drop-film coalescence process are mainly discussed. It is found that the decrease in the liquid–gas density ratio will result in incurve of the crown, especially when the density ratio is less than 100, due to the large gas velocity difference between the crown upper and lower positions. When the liquid–gas viscosity ratio is decreased to a value of less than 0.5, both splashing occurrence and crown expansion are suppressed, caused by the combination effect of the pressure difference and the gas velocity in the drop-film-contacting neck region. The density ratio has only minor influence on the drop coalescence process. However, when the viscosity ratio is decreased, the capillary wave on the drop surface gradually disappears. It is considered that the gas eddy reduction on the drop surface should be responsible for the capillary wave disappearance during drop coalescence. [ABSTRACT FROM AUTHOR]

Background: Hyperplasia of airway smooth muscle cells (ASMC) is a major contributor to airway remodeling in asthma. Transient receptor potential vanilloid 1 (TRPV1) is an important channel to mediate Ca2+ influx. This study explores the expression of TRPV1 channel and its effect on the proliferation and apoptosis in rat ASMC, in order to find a new target to treat airway remodeling in asthma. Methods: Rats were sensitized and challenged with ovalbumin to replicate asthmatic models. Proliferating cell nuclear antigen (PCNA) was detected by immunohistochemistry. Reverse transcriptase-polymerase chain reaction, immunocytochemistry, and Western blot were used to detect the mRNA and protein expression of TRPV1 channel. Intracellular calcium ([Ca2+]i) was detected using confocal fluorescence Ca2+ imaging. [3H] thymidine incorporation and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay were used to observe the DNA synthesis and proliferation. TUNEL assay was used to detect the apoptosis of ASMC. Results: (1) The expression of PCNA was significantly increased in intact asthmatic rat ASMC. (2) The expression of TRPV1 channel was significantly increased in asthmatic rat ASMC. (3) [Ca2+]i in ASMC of the asthmatic group was significantly increased. After treatment with TRPV1 agonist capsaicin (CAP), [Ca2+]i was further increased, whereas [Ca2+]i was decreased after administration of TRPV1 antagonist capsazepine (CPZ) in ASMC of the asthmatic group. (4) The DNA synthesis and absorbance of MTT were significantly increased, while apoptosis was significantly decreased in asthmatic ASMC. CAP further enhanced proliferation and decreased apoptosis. CPZ significantly inhibited the effect of CAP in asthmatic ASMC. Conclusion: TRPV1 channel was involved in the regulation of proliferation and apoptosis in asthmatic ASMC. [ABSTRACT FROM AUTHOR]

A rapid method based on hydrophilic interaction chromatography (HILIC) using UV detection was developed for analysis of diazepam and estazolam in human plasma. The method utilized a Kromasil KR100-5SIL column (250 mm × 4.6 mm I.D., 5 µm) with a mobile phase consisting of acetonitrile-sodium formate buffer (10 mM, pH = 5.5) (90:10,v/v) at a flow rate of 1.0 mL/min. The detection wavelength was 254 nm. The chromatographic run time was less than 5 min per injection. All the experiments were performed at room temperature. The isolation of the analytes from plasma samples was achieved by solid phase extraction (SPE) using Oasis HLB cartridges. The standard curve range was 25–5000 ng/mL (r2 > 0.99) for diazepam and estazolam using 0.2 mL of human plasma. The limit of quantification (LOQ) and limit of detection (LOD) for both compounds were 25 and 10 ng/mL, respectively. Recoveries of the analytes ranging from 70.7% to 88.5% with intra- and inter-day precision (RSD) less than 11% were obtained at the concentrations above the LOQ. The proposed method is rapid, simple, accurate, and its mobile phase is compatible for mass spectrometry, proving an alternative method for benzodiazepine drug monitoring in forensic and clinical toxicology as well as pharmacokinetic studies. [ABSTRACT FROM PUBLISHER]

Hydrophilic interaction chromatography (HILIC) has emerged as a viable option for many applications dealing with polar and hydrophilic analytes. The application of HILIC for the analysis of environmental samples has increased in the last years. Solid-phase extraction (SPE) coupled with HILIC-UV or MS (MS/MS) or ICP/MS has been utilized to pretreat, separate, and detect the residuals of numerous contaminants (pesticides, pharmaceuticals, drugs of abuse, free estrogens and their conjugates, aromatic amines, surfactants, metal complexes, etc.) in the environmental matrices. This article reviews the recent applications of this chromatographic technique in the environmental analysis. This review also presents a compilation of other reviews on HILIC. [ABSTRACT FROM AUTHOR]