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The accumulative freeze-thaw cycles in cold regions could cause deteriorations to concrete pavements. The measurement of air-void system inside hardened concrete is important for estimating the freeze-thawing performance of a concrete pavement. The segmentation of air voids from the concrete surface image is one of the most essential and challenging steps for automated air-void measurement. Conventional automated air-voids segmentation methods rely on a color enhancement step to manually create a contrast between air voids and non-air-voids. This study aims to investigate the use of a photometric stereo method for automated segmentation of air voids in hardened concrete surface without a need for contrast enhancement. In the study, the photometric stereo system with a Charge-Coupled Device (CCD) camera and six illumination lights was designed to collect images of polished concrete specimen surfaces under various lighting directions. Two air-void segmentation approaches were developed in the study. One approach interpreted the air voids by the surface depth. The other approach interpreted the air voids by the surface normal. Consequently, the segmentation results were refined by a set of image processing procedures. The results showed that the proposed automated air-void segmentation procedures could detect air voids in concrete surface with a satisfactory accuracy. [ABSTRACT FROM AUTHOR]

Nowadays, biodiesel has become a globally accepted renewable liquid fuel. The environmentally friendly enzymatic synthesis process is being widely researched. To solve the problem that production efficiency is low in enzymatic process, we optimized the structure of the static mixer by computational fluid dynamics (CFD) modeling. The optimal static mixer consists of 6 mixer units, and the length-diameter ratio of every mixer unit is 1.5. The enzymatic synthesis of biodiesel was conducted between waste cooking oil (WCO) and methanol by transesterification and esterification. The reaction conditions were also optimized in this designed static-mixed reactor. Under optimal conditions, the reaction time can save half time when compared with the traditional stirred reactor, which indicates that the static mixer has higher production efficiency. • Continuous reaction procedure for biodiesel production. • The static mixer reactor significantly reduced reaction time. • Efficiency of enzymatic-catalyzed biodiesel production was significantly improved. [ABSTRACT FROM AUTHOR]

• Automated segmentation of air voids from hardened concrete surface. • Three-dimensional image reconstruction method. • Deep learning strategies and process. The automated air-void detection methods specified in the ASTM C457 require the aid of contrast enhancement which is time consuming and labor intensive. This study investigated the utilization of three-dimensional (3D) reconstruction and Deep Convolution Neural Network (DCNN) methods to detect the air voids in hardened concrete surfaces without the use of contrast enhancement. The experimental results showed that the DCNN could accurately distinguish air voids from hardened concrete images with the detection accuracy of over 0.9 in only less than a minute. The accuracy rates for air content, specific surface, and spacing factor were 0.92, 0.91, and 0.89, respectively. [ABSTRACT FROM AUTHOR]

Currently, clinical intravesical instillation chemotherapy has been greatly compromised by the toxicological and physiological factors. New formulations that can specifically and efficiently kill bladder cancer cells are in urgent need to overcome the low residence efficiency and dose limiting toxicity of current ones. The combination of mucoadhesive nanocarriers and cancer cell selective prodrugs can to great extent address these limitations. However, the insignificant endogenous stimulus difference between cancer cells and normal cells in most cases and the high local drug concentration make it essential to develop new drugs with broader selectivity-window. Herein, based on the statistically different NQO1 expression between cancerous and normal bladder tissues, the reactive oxygen species (ROS) activatable epirubicin prodrug and highly potent NQO1 substrate, KP372–1, was co-delivered using a GSH-responsive mucoadhesive nanocarrier. After endocytosis, epirubicin could be promptly activated by the NQO1-dependent ROS production caused by KP372–1, thus specifically inhibiting the proliferation of bladder cancer cells. Since KP372–1 is much more potent than some commonly used NQO1 substrates, for example, β-lapachone, the cascade drug activation could occur under much lower drug concentration, thus greatly lowering the toxicity in normal cells and broadening the selectivity-window during intravesical bladder cancer chemotherapy. [Display omitted] • Mucoadhesive nanoparticles enhanced the adhesion and penetration of drugs in bladder; • KP372–1 activated epirubicin prodrug in cancer cells through NQO1-dependent way; • Dual-drug loaded nanoparticles selectively killed cancer cells and exempted normal cells; • Prodrug nanoparticles caused significant tumor inhibition and negligible side effect. [ABSTRACT FROM AUTHOR]

Data quality assurance (QA) procedures have been developed and implemented to evaluate the quality of automated pavement distress data. Most State Departments of Transportation (DOTs) use fixed acceptance thresholds to evaluate data quality at the network level and project level. However, errors of automated measurements can be affected by many factors such as pavement types and pavement conditions. It is necessary to take those factors into account while developing the QA acceptance thresholds. The objective of this research is to propose thresholding methods that could effectively utilise these factors to improve QA of the automated data. In this study, the potential problems associated with the use of fixed acceptance thresholds for QA were first discussed. Then, one conventional prediction interval method and one bootstrapping prediction interval method were proposed for QA procedures. The proposed prediction interval based methods can be used to determine variable thresholds that are sensitive to measurement errors. Lastly, QA results from the proposed methods and a fixed thresholding method were compared and analysed. The experimental results showed that prediction interval methods were superior to the fixed threshold methods in identifying pavement sections with data quality issues and evaluating the overall data quality of the network. [ABSTRACT FROM AUTHOR]

Data quality assurance (QA) procedures have been developed and implemented to evaluate the quality of automated pavement distress data. Most State Departments of Transportation (DOTs) use fixed acceptance thresholds to evaluate data quality at the network level and project level. However, errors of automated measurements can be affected by many factors such as pavement types and pavement conditions. It is necessary to take those factors into account while developing the QA acceptance thresholds. The objective of this research is to propose thresholding methods that could effectively utilise these factors to improve QA of the automated data. In this study, the potential problems associated with the use of fixed acceptance thresholds for QA were first discussed. Then, one conventional prediction interval method and one bootstrapping prediction interval method were proposed for QA procedures. The proposed prediction interval based methods can be used to determine variable thresholds that are sensitive to measurement errors. Lastly, QA results from the proposed methods and a fixed thresholding method were compared and analysed. The experimental results showed that prediction interval methods were superior to the fixed threshold methods in identifying pavement sections with data quality issues and evaluating the overall data quality of the network. [ABSTRACT FROM AUTHOR]

The aim of the current study was to assess the expression and clinical significance of serum microRNA (miR)-484 in patients with non-small cell lung cancer (NSCLC). Reverse transcription-quantitative polymerase chain reaction was performed to determine the expression of miR-484 in the serum of patients with NSCLC and NSCLC cell lines. Cell counting kit-8, flow cytometry, cell migration and cell invasion assays were performed to assess the role of miR-484 in the malignant changes associated with NSCLC cells. Furthermore, to assess the diagnostic value of miR-484, receiver operating curve (ROC) analysis was performed and the clinical relevance of serum miR-484 expression in patients with NSCLC was determined. A Kaplan-Meier analysis with the log-rank test was performed to assess the overall survival rate patients. To the best of our knowledge, the current study demonstrates for the first time that serum miR-484 was increased in patients with NSCLC compared with healthy controls. Additionally, serum miR-484 was revealed to be positively associated with histological grade, lymph node metastasis, distant metastasis and clinical stage. Patients with NSCLC and high serum miR-484 levels demonstrated significantly poorer overall survival rates compared with those exhibiting lower serum miR-484 expressions. ROC analysis revealed that serum miR-484 could screen patients with NSCLC patients from healthy controls with a high sensitivity and specificity. In vitro analysis also demonstrated that miR-484 was significantly upregulated in NSCLC cell lines, including 95D and H358 cells. Furthermore, the suppression of miR-484 decreased cell proliferation, cell migration and invasion. In summary, the results of the present study demonstrated that increased serum miR-484 expression is associated with the diagnosis and prognosis of patients with NSCLC. [ABSTRACT FROM AUTHOR]

The electrode erosion and lifetime performance of a compact and repetitively triggered field distortion spark gap switch were studied at a repetitive frequency rate of 30 Hz, a peak current of 8.5 kA, and a working voltage of ±35 kV when the switch was filled with a gas mixture of 30% SF6 and 70% N2 at a pressure of 0.3 MPa. The variations of the time-delay jitter and the self-breakdown voltage were both studied for the whole service lifetime of the spark gap switch. The morphology of both the electrodes and the plate insulator, before and after the service lifetime tests, is also analyzed. The results show that during these tests, the time-delay jitter is basically synchronized with the self-breakdown voltage jitter, and both undergo firstly a process of rapidly decreasing their values, then remaining stable, and finally and gradually increasing after 70 000 pulses. The change in the electrode surface roughness (i.e., surface profile) is caused by erosion and chemical deposits in the switch cavity, which are mainly the two factors that affect the time-delay jitter of the switch. Tip protrusions on the electrode surface, due to electrode erosion, contribute to reducing the time-delay jitter. However, due to chemical reactions, fluorides and sulfides are deposited on the switch components, as well as metal particles caused by electrode erosion sputtering. Slowly, after a large number of shots, all these phenomena affect the self-breakdown performance resulting in an increased self-breakdown voltage jitter, which also causes the time-delay jitter to increase. Although there are a number of reasons that contribute to the deterioration of the performance of the switch, it is fortunate that if a switch suffering a degraded performance is reassembled, with the electrodes mechanically polished and all the components cleaned, the optimal performance of the switch can be restored. If maintenance work is carried out regularly to preserve the condition of the switch’s inner components, the service lifetime of the switch can be prolonged. [ABSTRACT FROM AUTHOR]

This work was stimulated by the assumption that for a gas-filled spark gap closing switch operating at a high repetition frequency, there is an optimal frequency range in which the time-delay jitter reaches a minimum value. The experiments to test this assumption use an electrically triggered, field-distortion spark gap filled with the SF6/N2 gas mixture. The results show that indeed, the time-delay jitter decreases for a range of frequencies for which the filling gas can substantially restore the interelectrode insulation before increasing at a higher operation frequency. The experimental results demonstrate the correctness of the abovepresented assumption: the time-delay jitter of the field-distortion spark gap has its minimum when the unit operates in the repetition frequency range between 20 and 30 Hz. Since the recovery time depends on the gas species and the gap distance, the optimum operation frequency range should also vary depending on the spark–gap distance and the filling gas properties. [ABSTRACT FROM AUTHOR]

This paper describes the development of a small field-distortion spark gap switch. Comprehensive experimental studies made with the switch revealed its self-breakdown characteristics, voltage operating range, time delay and jitter, repetition frequency, and finally the electrode erosion processes and duration of its service lifetime. A series of design improvements were required to be implemented in the switch design. For example, to reduce the structural inductance of the switch and to improve its working characteristics, the main electrode was designed as a circular track structure. Similarly, to increase the operation stability and reduce the self-breakdown probability, the trigger electrode was designed as a disk-like structure. Moreover, to balance the gas pressure in the discharge region and increase the stability during closure, a circular hole was added at the center of the trigger electrode. The compact switch has a small size of only 150 mm $\times42$ mm, a weight of 1.5 kg, and can be successfully operated at a voltage over 110 kV, at a repetition rate between 1 and 50 Hz and having a jitter of less than 4 ns. It was experimentally demonstrated that during normal operation conditions, the switch lifetime exceeds 100 000 shots. [ABSTRACT FROM AUTHOR]

Abstract A compact low jitter high power repetitive long-pulse relativistic electron beam source with novel circuit structure and mechanical structure is presented. Based on Marx type circuit and direct-drive idea, the key technologies such as high energy density pulse forming network, repetitive high voltage pulse generator and low jitter electrical trigger technology are developed. The volume and weight of the pulsed electron beam source are reduced remarkably by using two-capacitor pulse forming modules, alternating superposition structure on both sides and high electric field shielding technology. The key technical parameters of the electron beam source design include a peak output voltage 1 MV with peak current 20 kA. The impulse is 180 ns and has a repetition frequency 1 ∼ 50 Hz, however, the output power and repetition frequency are able to be adjusted within a certain operating range. The machine has a total volume of 2.5 m3 and weighs 2.2 tons, making it much more compact than conventional electron beam sources. The experimental results show that when the e-beam source is operated under a single pulse condition, the output voltage, current, and power are 0.98 MV, 19.6 kA, and 19.2 GW, respectively. When the e-beam source has a continuous operating time of 10 s at a repetition frequency of 30 Hz and an output power of 16.7 GW, the voltage fluctuation range is limited to within ± 1.5%, and the current fluctuation range is limited to within ± 2%. The delay time jitter between the trigger pulse and the output pulse is limited less than 6.5 ns standard mean deviation. Statistical distributions of the delay time jitter and current amplitude variation of the 300 pulses are approximately Gaussian. When the cooling system is working, the electron beam source can work continuously for 100 s under the conditions of an output power of 16.7 GW and repetition frequency of 30 Hz, and the system operation is stable and reliable. [ABSTRACT FROM AUTHOR]