Accelerated Design for Perovskite-Oxide-Based Photocatalysts Using Machine Learning Techniques.

The rapid discovery of photocatalysts with desired performance among tens of thousands of potential perovskites represents a significant advancement. To expedite the design of perovskite-oxide-based photocatalysts, we developed a model of ABO3-type perovskites using machine learning methods based on atomic and experimental parameters. This model can be used to predict specific surface area (SSA), a key parameter closely associated with photocatalytic activity. The model construction involved several steps, including data collection, feature selection, model construction, web-service development, virtual screening and mechanism elucidation. Statistical analysis revealed that the support vector regression model achieved a correlation coefficient of 0.9462 for the training set and 0.8786 for the leave-one-out cross-validation. The potential perovskites with higher SSA than the highest SSA observed in the existing dataset were identified using the model and our computation platform. We also developed a webserver of the model, freely accessible to users. The methodologies outlined in this study not only facilitate the discovery of new perovskites but also enable exploration of the correlations between the perovskite properties and the physicochemical features. These findings provide valuable insights for further research and applications of perovskites using machine learning techniques.

A machine learning-based nano-photocatalyst module for accelerating the design of Bi2WO6/MIL-53(Al) nanocomposites with enhanced photocatalytic activity.

It is a great challenge to acquire novel Bi2WO6/MIL-53(Al) (BWO/MIL) nanocomposites with excellent catalytic activity by the trial-and-error method in the vast untapped synthetic space. The degradation rate of Rhodamine B dye (DRRhB) can be used as the main parameter to evaluate the catalytic activity of BWO/MIL nanocomposites. In this work, a machine learning-based nano-photocatalyst module was developed to speed up the design of BWO/MIL with desirable performance. Firstly, the DRRhB dataset was constructed, and four key features related to the synthetic conditions of BWO/MIL were filtered by the forward feature selection method based on support vector regression (SVR). Secondly, the SVR model with radical basis function for predicting the DRRhB of BWO/MIL was established with the key features and optimal hyperparameters. The correlation coefficients (R) between predicted and experimental DRRhB were 0.823 and 0.884 for leave-one-out cross-validation (LOOCV) and the external test, respectively. Thirdly, potential BWO/MIL nanocomposites with higher DRRhB were discovered by inverse projection, the prediction model, and virtual screening from the synthesis space. Meanwhile, an online web service (http://1.14.49.110/online_predict/BWO2) was built to share the model for predicting the DRRhB of BWO/MIL. Moreover, sensitivity analysis was brought into boosting the model's explainability and illustrating how the DRRhB of BWO/MIL changes over the four key features, respectively. The method mentioned here can provide valuable clues to develop new nanocomposites with the desired properties and accelerate the design of nano-photocatalysts.

Monitoring of thermal stress in metal plates by using bonded shear horizontal wave piezoelectric transducers.

Thermal stress is one of the major causes of failure of engineering structures and its measurement has attracted more attention in recent years. The ultrasonic wave method is very promising in stress measurement due to its non-destructive nature and easy manipulation. The traditional ultrasonic wave transducers require a coupling medium which would introduce large repeatability errors in travel time measurement and thus in the measured stress. In this work, a methodology based on bonded shear horizontal (SH) guided wave piezoelectric transducers was developed to monitor thermal stress in metal plates. The adhesive bonding between the transducer and the specimen ensures the repeatability in travel time measurements, and the strain gauges are also employed to monitor the wave path length. The dispersive equation of acoustoelastic SH wave propagating in an isotropic medium under the uniaxial stress is derived. Both the uniaxial tension test and thermal modulation test have been performed in aluminum and steel plates. The results show that the acoustoelastic constants of the SH0 wave are identical to that of the shear bulk wave as predicted by the acoustoelastic theory and the thermal stress measured from -60 °C to 100 °C by the proposed method has a very good repeatability (better than 2 MPa) in both the aluminum and steel plates. Considering the convenience and reliability of the bonded SH0 wave piezoelectric transducer, the proposed method is very promising for monitoring of thermal stress in engineering structures, such as rails, etc.

An omnidirectional piezoelectric transducer for selective excitation and reception of high-order shear horizontal waves.

Guided wave tomography, as an advanced structural health monitoring (SHM) method, has offered a feasible solution to wall thickness quantification which is essential in petrochemical industries. However, previously used low-frequency Lamb waves (A0 and S0) limit the resolution of tomography. Recently, the first-order shear horizontal guided wave (SH1) was found very promising in tomography for its capability in resolution improvement. However, the SHM-required omnidirectional piezoelectric transducers for selectively generating and receiving the SH1 wave, namely OSH1-PT, are not available yet. In this work, a general method was developed to design an OSH1-PT based on the thickness-poled PZT half-ring configuration. Firstly, the excitation function of the OSH1-PT was explicitly derived and validated through finite element simulations. Secondly, a design formula was obtained and used to determine the size of the OSH1-PT. Then, the designed OSH1-PT was fabricated and tested by using a 2D laser Doppler vibrometer. Significant mode selectivity was observed in all directions (0 âˆ¼ 90°) with the excited SH1 to SH0 ratio higher than 15 dB. Pitch-catch tests were conducted from 400 âˆ¼ 520 kHz and the received SH1 to SH0 ratio was found higher than 19 dB at all frequencies and reached its maxima of 30.7 dB at 490 kHz, which is very close to the designed working frequency of 500 kHz. Finally, an OSH2-PT was theoretically designed and validated by FE simulations. Due to its simplicity and effectiveness in designing the OSHn-PT, the proposed method is expected to pave the road to wide applications of high-order SH wave tomography.

Correlation of the detection rate of upper GI cancer with artificial intelligence score: results from a multicenter trial (with video).

BACKGROUND AND AIMS: The quality of EGD is a prerequisite for a high detection rate of upper GI lesions, especially early gastric cancer. Our previous study showed that an artificial intelligence system, named intelligent detection endoscopic assistant (IDEA), could help to monitor blind spots and provide an operation score during EGD. Here, we verified the effectiveness of IDEA to help evaluate the quality of EGD in a large-scale multicenter trial. METHODS: Patients undergoing EGD in 12 hospitals were consecutively enrolled. All hospitals were equipped with IDEA developed using deep convolutional neural networks and long short-term memory. Patients were examined by EGD, and the results were recorded by IDEA. The primary outcome was the detection rate of upper GI cancer. Secondary outcomes were part scores, total scores, and endoscopic procedure time, which were analyzed by IDEA. RESULTS: A total of 17,787 patients were recruited. The total detection rate of cancer-positive cases was 1.50%, ranging from .60% to 3.94% in each hospital. The total detection rate of early cancer-positive cases was .36%, ranging from .00% to 1.58% in each hospital. The average total score analyzed by IDEA ranged from 64.87 ± 16.87 to 83.50 ± 9.57 in each hospital. The cancer detection rate in each hospital was positively correlated with total score (r = .775, P = .003). Similarly, the early cancer detection rate was positively correlated with total score (r = .756, P = .004). CONCLUSIONS: This multicenter trial confirmed that the quality of the EGD result is positively correlated with the detection rate of cancer, which can be monitored by IDEA. (Clinical trial registration number: ChiCTR2000029001.).

MicroRNA­199a­5p suppresses cell proliferation, migration and invasion by targeting ITGA3 in colorectal cancer.

As a member of the integrin family, integrin α3ß1 (ITGA3) has been linked to intercellular communication and serves an important role in the signaling among cells and the extracellular matrix. MicroRNA (miR)­199a­5p has been demonstrated to be related to the pathogenesis and progression of multiple malignant diseases. However, the biological functions of miR­199a­5p and ITGA3 in colorectal cancer (CRC) have rarely been reported. The aim of the present study was to explore the roles of miR­199a­5p and ITGA3 in CRC. Immunohistochemistry staining and western blotting were applied to detect the protein expression of ITGA3 in CRC tissues and cells. Reverse transcription­quantitative PCR was performed to investigate the expression of miR­199a­5p and ITGA3 mRNA. HCT­116 cells were transfected with miR­199a­5p mimics, mimics control, short hairpin RNA targeting ITGA3, or pcDNA­ITGA3 for the functional experiments. Dual luciferase reporter assay was applied to confirm whether miR­199a­5p targeted the 3' untranslated region (3'UTR) of ITGA3. The MTT, Transwell and wound healing assays were used to evaluate the proliferation, invasion and migration of CRC cells. Immunofluorescence assay was used to monitor the epithelial­mesenchymal transition (EMT) biomarker expression. The results demonstrated downregulation of miR­199a­5p and upregulation of ITGA3 in CRC tissues and cell lines. miR­199a­5p mimics and knockdown of ITGA3 suppressed the proliferation, invasion and migration of CRC cells. Bioinformatics analysis and luciferase reporter assay indicated that miR­199a­5p targeted the 3'UTR of the ITGA3 transcript, and overexpression of ITGA3 reversed the tumor­suppressive effects of miR­199a­5p elevation. In addition, the immunofluorescence assay suggested that miR­199a­5p mimics suppressed the EMT of CRC cells, whereas the overexpression of ITGA3 restored this effect. In conclusion, miR­199a­5p may act as a tumor suppressor by targeting and negatively regulating ITGA3 in CRC.

A high-sensitivity and long-distance structural health monitoring system based on bidirectional SH wave phased array.

When estimating a structural health monitoring (SHM) system, its defect sensitivity and area/distance coverage are most important factors. For commonly used guided wave sparse array system, it usually requires a reference state as the baseline which is not available in many cases. In comparison, phased array technique typically does not need the baseline in simple structures and it had been successfully used in nondestructive testing (NDT). However, currently developed phased array systems employed omni-directional transducers routinely, where the wave energy is distributed equally along all directions thus it is not favorable for long-distance detection. In this work, bidirectional piezoelectric transducers were used to form a linear phased array system, which can generate/receive shear horizontal (SH) wave with high energy concentration. Firstly, the configuration of the employed transducer composed by antiparallel d15 piezoelectric strips (APS) was presented. Then the total focusing method (TFM) employed for defect detection was introduced. After validating the radiation pattern of SH wave generated by the APS, the properties of beam steering for the proposed phased array was investigated. Finally, experiments were carried out to validate its performance in detection of various defects. Results indicated that even for a 1 mm through-thickness hole 700 mm away, the proposed phased array system can still detect it accurately, which is much better than previous SHM systems. Dual defects including a crack and a hole can also be clearly detected without baseline. The high-sensitivity of the proposed system was attributed to the employed bidirectional transducer which can generate non-dispersive SH0 wave with high energy concentration. This proposed SH wave phased array system will provide a high-performance SHM method for plate-like structures.

Long-distance structural health monitoring of buried pipes using pitch-catch T(0,1) wave piezoelectric ring array transducers.

In modern industries, long-distance guided wave inspection has been routinely used for various types of pipelines. The usage of T(0,1) wave is always of great interests since it is the only non-dispersive wave mode in pipes. In this work, a pair of pitch-catch piezoelectric ring arrays were proposed for long-distance structural health monitoring (SHM) of buried pipes. Firstly, the working principle of the proposed transducer was introduced. Next, the performances of thickness-shear (d15) and face-shear (d24) modes based piezoelectric ring transducers in T(0,1) wave generation and reception were comparatively tested. It was found that at most frequencies, it is best to employ the d15 ring as the exciter and the d24 ring as the receiver. Then, the signal-to-noise ratio (SNR) of the generated T(0,1) wave and its attenuation in pipes with different coating conditions were investigated to estimate the detectable distance using the proposed transducer. Results showed that after applying acoustical isolation layer on pipes, the proposed ring transducers can inspect buried pipes over 20 m. Finally, the performance of the ring transducers in defect detection was validated. This work is expected to provide a promising solution to long-distance SHM of buried pipes.

A tunable bidirectional SH wave transducer based on antiparallel thickness-shear (d15) piezoelectric strips.

Guided wave based defects inspection is very promising in the field of structural health monitoring (SHM) and nondestructive testing (NDT) due to its less dissipation and thus long distance coverage. In comparison with the widely used Lamb waves, shear horizontal (SH) waves are relatively simple but less investigated probably due to the traditional notion that SH waves were usually excited by electromagnetic acoustic transducers (EMAT). In this work, we proposed a tunable method to excite single-mode bidirectional SH waves in plates using antiparallel thickness-shear (d15) piezoelectric strips (APS). The proposed SH wave driving mechanism here is similar to that by using the periodic permanent magnetics (PPM) based EMAT with the period of strips equal to half of the wavelength. Both finite element simulations and experiments were conducted to validate this transducer in excitation of bidirectional SH waves. Results show that the Lamb waves excited by single piezoelectric strip can be suppressed very well. The radiation angle of the excited bidirectional SH wave can be reduced by extending the strip length, increasing the driving frequency or using more strips. Moreover, the APS transducer can selectively excite SH1 wave and suppress the SH0 wave at 174 kHz and 273 kHz in a 10 mm-thick aluminum plate. Considering its simple structure, flexible design and low excitation energy, the APS SH wave transducer is expected to be widely used in near future.

A high-resolution structural health monitoring system based on SH wave piezoelectric transducers phased array.

Guided wave based structural health monitoring (SHM) has been regarded as an effective tool to detect the early damage in large structures and thus avoid possible catastrophic failure. In recent years, Lamb wave phased array SHM technology had been intensively investigated while the inherent multi-mode and dispersive characteristic of Lamb waves limits its further applications. In comparison, the fundamental shear horizontal (SH0) wave is non-dispersive with uncoupled displacements and thus more promising for defect detection. In this work, we proposed an SH0 wave linear phased array SHM system based on our recently proposed omni-directional SH wave piezoelectric transducer (OSH-PT). Firstly, the working principle of the phased array system was presented and the total focusing method (TFM) was employed for imaging. Then the SH0 wave mode generated by the OSH-PT was confirmed in a defect-free plate. Finally, experiments were carried out to examine the performances of this SHM system. Results showed that the proposed system can detect a through-thickness hole as small as 2 mm in diameter with the location error only about 6.3 mm. Moreover, the proposed phased array system can also detect multi-defects. Due to its low working frequency and thus low attenuation, the proposed phased array system is capable of monitoring large structures. This work will lay the foundations of SH wave based phased array SHM.

Excitation of moderate-frequency Love wave in a Plexiglas plate on aluminum semi-space.

Love waves are of great importance in geophysics, electronics, and engineering. Despite intensive studies on high-frequency Love waves for delay lines and chemical/biomedical sensors, moderate-frequency and low-frequency Love waves have seldom been investigated. Here, Love waves in a 2-mm-thick Plexiglas plate bonded on a 50-mm-thick aluminum block were successfully excited and received by using d24 and d15 shear mode PZT wafers. A d31 mode PZT wafer was also employed as the sensor, and results show that no Rayleigh-Lamb type waves were generated. The group velocity curve of the excited Love wave from 120 to 525 kHz matches the theoretical curve well. This work could promote applications of Love waves in many engineering fields.

A practical omni-directional SH wave transducer for structural health monitoring based on two thickness-poled piezoelectric half-rings.

Structural health monitoring (SHM) has become more and more important in modern industries as it can monitor the safety of structures during the full service life and prevent possible losses of life and economics. Shear horizontal wave in plate-like structures is very useful for long distance inspection since its fundamental mode (SH0) is totally non-dispersive. However, all the currently available SH wave transducers are not suitable for practical SHM because of their complicated structures. In this work, we firstly investigated via finite element (FEM) simulations the performances of thickness-poled d15 PZT ring based omni-directional SH wave piezoelectric transducers (OSH-PT) consisting of different number of elements. Results show that the two-half-ring based OSH-PT can have perfect omni-directivity and acceptable performances in excitation/reception of SH0 waves. Then, experimental testing on a 21 mm outer-diameter (OD), 9 mm inner-diameter (ID) two-half-ring OSH-PT shows that it exhibits acceptable but not desirable performances in both excitation and reception of SH0 wave. Finally, size optimization was conducted on the two-half-ring based OSH-PT using FEM simulations and results showed that its performances can be fairly enhanced by reducing the outer diameter of the half-ring. Testing results on a 12 mm-OD, 6 mm-ID OSH-PT show that the SH0-to-Lamb waves ratio in the case of self-excitation and self-reception can be over 20 dB from 115 kHz to 250 kHz, which is good enough for practical applications. The proposed two-half-ring OSH-PT is expected to be widely used in SH0 wave based SHM due to its simple structure, easy fabrication/assembling, low cost and good performances.

A Comparative Study of Three Types Shear Mode Piezoelectric Wafers in Shear Horizontal Wave Generation and Reception.

Guided wave-based inspection has emerged as a promising tool to evaluate the reliability of key components in modern industries. The fundamental shear horizontal (SH0) wave is always of great interests for plate-like structures because of its non-dispersion characteristics. However, the generation and reception of SH0 wave using piezoelectric wafers is not straightforward. In this paper, we firstly define three types shear mode piezoelectric wafers, i.e., the conventional in-plane poled thickness-shear (d15) mode, the thickness-poled thickness-shear (d15) mode, and the face-shear (d24) mode. Then, finite element simulations were conducted to demonstrate their performance in SH wave generation and reception. The results indicated that the face shear d24 wafer can generate almost single mode SH0 wave, while both types of d15 wafers would generate Lamb waves and SH0 wave simultaneously. Finally, experiments were carried out to check the efficiency of different shear mode piezoelectric wafers in SH0 wave generation and reception. The results indicated that the d24 wafer can generate and receive SH0 wave of high signal to noise ratio (SNR) with high energy conversion efficiency, while the in-plane poled d15 wafer would generate SH0 wave of high amplitude and acceptable SNR but with relatively low energy conversion efficiency. The performances of thickness-poled d15 wafer was not as good as the other two in both SH wave generation and reception. This work will be helpful for the applications of SH waves in plate-like structures.

Predicting the toxicities of metal oxide nanoparticles based on support vector regression with a residual bootstrapping method.

For safely using the untested metal oxide nanoparticles (MONPs) in industrial and commercial applications, it is important to predict their potential toxicities quickly and efficiently. In this research, the quantitative structure-activity relationship (QSAR) model based on support vector regression (SVR) with a residual bootstrapping technique (BTSVR) was proposed to predict the toxicities of MONPs. It was found that the main features influencing the toxicities of MONPs were RAatom (atomic ratio of oxygen to metal), ΔHm (enthalpy of melting), and Ecoh (cohesive energy). The QSPR model constructed was robust and self-explanatory in predicting the toxicities of MONPs with the coefficient of determination (R2) of 0.87 and the root mean square error (RMSE) of 0.184 for the training sets, and R2 of 0.84 and RMSE of 0.217 for the testing sets, respectively. The performance of our model is much better than that published. Moreover, our model was validated by the external testing sets 1000 times. Therefore, it is expected that the method presented here can be used to construct powerful model in predicting the toxicities of MONPs untested or even unavailable.

Seven-day triple therapy is a better choice for Helicobacter pylori eradication in regions with low antibiotic resistance.

AIM: To investigate whether 7-d triple therapies are still valid in populations with low levels of resistance. METHODS: A total of 1106 Helicobacter pylori (H. pylori)-positive patients were divided into three groups, each of which received one type of 7-d triple therapy. Therapeutic outcomes of the patients were assessed by the (13)C-urea breath test at 8 wk after treatment. The susceptibility of H. pylori to antibiotics was determined by an agar-dilution method. Data analysis was performed by χ(2) tests. RESULTS: The eradication rates in groups A, B and C were 90.71% (332/366), 90.46% (313/346) and 90.87% (189/208), respectively (P = 0.986). The resistance rates were 8.91% for clarithromycin, 14.78% for levofloxacin and 0% for amoxicillin. The eradication rate was significantly different between clarithromycin- and levofloxacin-resistant patients (P < 0.05) in group A. Patients whose treatment failed in group A also had a higher clarithromycin resistance rate than did successive patients (P = 0.034). However, levofloxacin resistance had no obvious influence on the eradication rate. Furthermore, three main antibiotics (clarithromycin, levofloxacin and amoxicillin) had lower DID (defined daily dose per 1000 inhabitants per day) in this city. CONCLUSION: Clarithromycin resistance is the main reason for the failure of 7-d triple therapy. In populations with low levels of resistance, a 7-d triple therapy is a viable choice. The choice of therapy should not be influenced by conditions in high antibiotic resistance regions.