Wintertime Optical Properties of Primary and Secondary Brown Carbon at a Regional Site in the North China Plain.

The light-absorbing properties of atmospheric brown carbon (BrC) are poorly understood due to its complex chemical composition. Here, a black-carbon-tracer method was coupled with source apportionments of organic aerosol (OA) to explore the light-absorbing properties of primary and secondary BrC from the North China Plain (NCP). Primary emissions of BrC contributed more to OA light absorption than secondary processes, and biomass burning OA accounted for 60% of primary BrC absorption at λ = 370 nm, followed by coal combustion OA (35%) and hydrocarbon-like OA (5%). Secondary BrC absorption was high in the early morning and later decreased due to the bleaching of chromophores. Nighttime aqueous-phase chemistry promoted the formation of secondary light-absorbing compounds and the production of strongly absorbing particles. Source analysis showed that the NCP region was the most important source for primary and secondary BrC subtypes at the study site. The mean direct radiative forcing for BrC was 0.15 W m-2 (0.11 W m-2 and 0.04 W m-2 for the primary and secondary fractions, respectively). This study provides new information on the optical properties of primary and secondary BrC and highlights the importance of atmospheric oxidation on BrC absorption.

Two Common MTHFR Gene Polymorphisms (C677T and A1298C) and Fetal Congenital Heart Disease Risk: An Updated Meta-Analysis with Trial Sequential Analysis.

BACKGROUND/AIMS: Published studies indicated that the MTHFR gene polymorphisms C677T and A1298C are associated with congenital heart disease (CHD) risk in children, but obtained inconsistent results. Our study aims to reach a more accurate association between these two polymorphisms and CHD risk. METHODS: Eligible studies were obtained by screening the PubMed, Embase, China National Knowledge Infrastructure, Wan Fang and VIP databases based on designed searching strategy. The odds ratio (OR) and 95% confidence interval (CI) were calculated. Moreover, a trial sequential analysis was introduced to confirm the positive results and an RNA secondary structure analysis was also applied to discover the potential molecular mechanism. RESULTS: Based on thirty-two published articles, involving 6988 congenital heart disease subjects and 7579 healthy controls, the pooled results from the C677T polymorphism in the fetal population showed increased risks in allelic model (OR=1.32, 95%CI=1.14-1.53), recessive model (OR=1.69, 95%CI=1.25-2.30), dominant model (OR=1.35, 95%CI=1.11-1.64), heterozygote model (OR=1.20, 95%CI=1.01-1.41) and homozygote model (OR=1.75, 95%CI=1.31-2.33). An increased risk was only detected in the A1298C polymorphism in the overall fetal popalation in a recessive model (OR=1.42, 95%CI=1.10-1.84). In the subgroup stratified by region, sample size, genotyping method and source of controls, the increased risks were widely observed in both the C677T and A1298C polymorphisms with CHD risk. Furthermore, trial sequential analysis confirmed our positive results, and the RNA secondary structure analysis detected the changes in the RNA secondary structure caused by the mutant 677T allele and 1298C allele. CONCLUSION: In summary, we found that the MTHFR C677T polymorphism is associated with a significant increased risk in congenital heart disease in the fetal population. Moreover, an increased risk in the CC genotype of MTHFR A1298C polymorphism was observed, but the protective role of the 1298C allele needs further study.

A Uniform Linear Multi-Coil Array-Based Borehole Transient Electromagnetic System for Non-Destructive Evaluations of Downhole Casings.

Borehole transient electromagnetic (TEM) techniques have been proven to be efficient for nondestructive evaluations (NDEs) of metal casings using eddy-current properties. However, physical limitations and bad borehole conditions restrict the use of eddy-current sensors, which makes downhole casing inspections very different from those of conventional NDE systems. In this paper, we present a uniform linear multi-coil array-based borehole TEM system for NDEs of downhole casings. On the basis of the borehole TEM signal model, a numerical multi-coil array approach using the Gauss⁻Legendre quadrature is derived. The TEM response can be divided into two independent parts related to the transmitting-receiving distance (TRD) and the observation time and casing thickness. Using this property, the signal received by the multi-coil array is weighted to cancel the influence of the TRDs of the different array elements to obtain the optimal response according to the linearly constrained minimum variance criterion, which can be shown to be identical to that of achieving the maximum signal-to-noise ratio. The effectiveness of the proposed method was verified by applying the uniform linear multi-coil array to a borehole TEM system for NDEs of oil-well casings. Field experiments were conducted, and the results demonstrate the effectiveness of the proposed method.

Auxiliary Sensor-Based Borehole Transient Electromagnetic System for the Nondestructive Inspection of Multipipe Strings.

Transient electromagnetic (TEM) techniques are widely used in the field of geophysical prospecting. In borehole detection, the nondestructive inspection (NDI) of a metal pipe can be performed efficiently using the properties of eddy currents. However, with increasing concern for safety in oil and gas production, more than one string of pipe is used to protect wellbores, which complicates data interpretation. In this paper, an auxiliary sensor-based borehole TEM system for the NDI of multipipe strings is presented. On the basis of the characteristics of the borehole TEM model, we investigate the principle behind the NDI of multipipe strings using multiple time slices of induced electromotive force (EMF) in a single sensor. The results show that the detection performance of NDI is strongly influenced by eddy-current diffusion in the longitudinal direction. To solve this problem, we used time slices of the induced EMF in both the main and auxiliary sensors. The performance of the proposed system was verified by applying it to an oil well with a production casing and liner. Moreover, field experiments were conducted, and the results demonstrate the effectiveness of the proposed method.

[Analysis and Correction of Spectral Curvature in Hadamard Transform Spectrometer with DMD].

Due to the advantages of its low cost and high utilization rate of light energy and no moving parts, Hadamard transform spectrometer with DMD has become a focus in the research of spectrometer. In order to solve the reduction of spectral resolution caused by the spectral curvature of Hadamard transform spectrometer with DMD (Digital Micro-mirror Device), the spectral aliasing in the spectrometer was investigated. Firstly, the mathematical relationship of spectral aliasing to radius of spectral curvature was deduced. Then, two procedures were proposed to solve the spectral aliasing. One is making the DMD encoded spectral band accordant with the standard spectral band as far as possible by adjusting the DMD-encoded stripe, and another is correcting remaining spectral aliasing by means of data processing. Finally, by analyzing and correcting spectral curvature in six situations of the curvature radius of 15.8 x 104, 7.8 x 104, 9.7 x 104 µm and etc, we fit out the relationship of spectral aliasing and spectrum correction effect of spectral-curvature to the curvature radius. The simulation indicates that the spectral resolution increases to the resolution of optical system. It shows that the proposed methods are universal, simple and effective in the improvement of spectral resolution.

Research on water content measurement method based on heat transfer method.

During the measurement of multiphase flow in low yield oil wells, the liquid volume will vary with the operating characteristics of the pumping unit. Using the pulsating characteristics of the up and down strokes of a pumping unit, the flow rate is measured when there is a flow rate on the up stroke, and the water content is measured when the fluid is stationary on the down stroke. In this paper, the heat transfer method is used to measure the water content of the oil water mixture during the down stroke process. At this time, the water content can be expressed as the instantaneous water content of the oil well. Firstly, the feasibility of measuring water content using heat transfer method is demonstrated theoretically, and then the temperature change of the heating probe PT300 is simulated. Finally, the actual temperature of PT300 is measured experimentally. Comparing the experimental value with the simulation value, the calculated measurement error is within 1.27 %, which indicates that the heat transfer method is feasible for measuring water content. Using the same single sensor to measure oil water two-phase flow using the pulsation characteristics of the up and down strokes of a pumping unit is a major innovation in this paper. And lays a foundation for the detection of multiphase flow using heat transfer methods. The successful implementation of the text heat transfer method for measuring water content has broken the previous situation of multiple sensor detection, simplified the structure of multiphase flow instruments, and extended the life of the instrument.

Flow regimes identification of air water counter current flow in vertical annulus using differential pressure signals and machine learning.

This study investigates the gas-liquid two-phase counter-current flow through a vertical annulus, a phenomenon prevalent across numerous industrial fields. The presence of an inner pipe and varying degrees of eccentricity between the inner and outer pipes often blur the clear demarcation of flow regime boundaries. To address this, we designed a vertical annulus with adjustable eccentricity (outer and inner diameters of 125 mm and 75 mm, respectively). We conducted gas-liquid counter-current flow experiments under specific conditions: gas superficial velocity ranging from 0.06 to 5.04 m/s, liquid superficial velocity from 0.01 to 0.25 m/s, and five levels of eccentricity (e = 0, 0.25, 0.5, 0.75, 1). We collected differential pressure data at two distinct height distances (DP1: 50 mm and DP2: 1000 mm). We used vectors, composed of both the probability density functions (PDFs) of the differential pressure signals and the power spectral density (PSD) reduced via Principal Component Analysis, as features. Using the CFDP clustering algorithm-based on local density-we clustered the flow regimes of the experimental data, thereby achieving an objective and consistent identification of the flow regime of gas-liquid two-phase counter-current flow in a vertical annulus. Our analysis reveals that for DP1, the main differences in the PSD of various flow regimes occur within the 0.5-1 Hz range. Among the three flow regimes involved, the slug flow exhibits the highest power intensity, followed by the bubbly flow, with the churn flow having the least. In terms of differential pressure distribution, the bubbly and churn flows have a concentrated distribution, while the slug flow is more dispersed. For DP2, the PSD differences primarily exist within the 0.5-2 Hz range. The churn flow has the highest power intensity, followed by the slug flow, with the bubbly flow being the weakest. Here, the bubbly flow's differential pressure distribution is concentrated, while the slug and churn flows are more dispersed. Based on the results of the flow regime classification, we generated a flow regime map and analyzed the influence of annulus eccentricity on the flow regime. We found that in most cases, pipe eccentricity does not significantly affect the flow regime. However, in the transition region-such as the bubbly to slug flow transition zone-flows with medium eccentricity values (e = 0.5, 0.75) are more likely to transition to slug flow. We compared the visual recognition results of flow regimes with the clustering results. 4.04% of the total samples showed different results from visual recognition and clustering, primarily located in the flow regime transition area. Since visually distinguishing flow regimes in these areas is typically challenging, our methodology offers an objective classification approach for gas-liquid two-phase counter-current flow in a vertical annulus.

Overexpressed microRNA (miR)-382-3p promoted vascular remodeling via suppressing autophagy-related protein 7 (ATG7) in chronic thromboembolic pulmonary hypertension.

BACKGROUND: This research has investigated the role of miR-382-3p in chronic thromboembolic pulmonary hypertension (CTEPH). METHODS: Human pulmonary artery smooth muscle cells (hPASMCs) were treated with PDGF-BB to induce proliferation, and then transfected with miR-382-3p mimic, miR-382-3p inhibitor, ATG7 overexpression plasmid, and siATG7. MiR-382-3p, ATG7, VEGF, PCNA, p62, and LC3-Ⅱ/LC3-I levels were detected by qRT-PCR and Western blotting. Cell viability and migration were tested through CCK-8 and wound healing assays, respectively. Target genes of miR-382-3p were predicted by Targetscan and starBase, and pathway analysis was implemented through WebGestalt. The binding relationship between miR-382-3p and ATG7 was analyzed by the dual-luciferase reporter and RIP assays. A CTEPH model was constructed in rats with the treatment of miR-382-3p antagomir or agomir, and mean pulmonary artery pressure (mPAP) was measured. Lung tissue was observed through the HE staining assay. RESULTS: MiR-382-3p level in hPASMCs was obviously upregulated with the increasing dose of PDGF-BB. MiR-382-3p mimic promoted yet miR-382-3p inhibitor suppressed hPASMC proliferation. MiR-382-3p directly targeted ATG7. ATG7 overexpression repressed hPASMC proliferation and migration, whereas siATG7 exerted the opposite effects. ATG7 overexpression partly neutralized the effects of miR-382-3p mimic on proliferation, migration, and autophagy-related proteins (ATG7, p62, and LC3-Ⅱ/LC3-I) in hPASMCs, whereas siATG7 partly offset the impacts of miR-382-3p inhibitor. MiR-382-3p antagomir reversed CTEPH-induced mPAP elevation, miR-382-3p upregulation, thickening of the pulmonary artery wall, and increased expressions of VEGF, PCNA, and autophagy-related proteins in rats, while miR-382-3p agomir potentiated these effects induced by CTEPH. CONCLUSION: Overexpressed miR-382-3p promotes vascular remodeling via ATG7 inhibition in CTEPH.

The enhanced beam sweeping algorithm for DOA estimation in the hybrid analog-digital structure with nested array.

As an emerging technology, the hybrid analog-digital structure has been considered for use in future millimeter-wave communications. Although this structure can reduce the hardware cost and power consumption considerably, the spatial covariance matrix (SCM), as the core of subspace-based direction of arrival (DOA) estimation, cannot be obtained directly. Previously, the beam sweeping algorithm (BSA) has been found effective for reconstructing the spatial covariance matrix and realizing DOA estimation by forming the beams to difference directions. However, it is computationally intractable owing to the high-dimensional matrix operation. To address this problem and improve the DOA estimation performance, this paper applies the nested array to the hybrid analog-digital structure and proposes the enhanced BSA (EBSA) for DOA estimation. By deleting a large number of redundant elements exist in the SCM to be reconstructed, the computational cost can be considerably reduced. Also, the nested array can offer high degrees of freedom. Finally, simulation experiments are conducted to verify the performance of EBSA. The results indicate that the proposed EBSA is better than the state-of-the-art method in terms of estimation accuracy and computational cost.

The effect of phosphorus on solidification behaviour of undercooled Al-70 wt.%Si alloys.

Effect of refining element phosphorus (P) on the morphology of the primary silicon in the Al-70 wt.%Si alloy was investigated via the electromagnetic levitation (EML) technique. The morphology and microstructure were analyzed by using high-speed video (HSV) and scanning electron microscopy (SEM). It was found that the morphology of primary silicon transformed from dendrites with several branches to blocky shape, and then to equiaxed grains in Al-70 wt.%Si and Al-70 wt.%Si-1.0 wt.%P alloys with increasing of undercooling. The nucleation number and nucleation rate increased exponentially with the increase of undercooling for both alloys. Finally, the growth velocity of primary silicon was discussed in combination with classical theory.