•The optimization of NSI-A + B system can improve the friction reduction effect.•By the friction reduction rate test, NSI-A + B system shows excellent properties.•Microstructure and rheology explain ...reasons for its excellent properties.•Friction reduction formula is proposed through indoor tests and verified in field.
Slickwater is widely used in unconventional reconstruction, but its sand-carrying capacity is weak, and the influencing factors of friction reduction are not clear. To cope with various complex working conditions, it is necessary to develop a new system with strong sand-carrying capacity and good friction reduction tolerance. In this paper, polymer with high friction reduction rate is selected firstly, and then a new type of viscoelastic slickwater system is formed by adding nano-emulsion. Then, the relationship between the friction reduction performance and temperature, shear flow, salinity of the slickwater system was studied. The influence on the microstructure of the slickwater with the change of friction reduction rate under various factors was analyzed by using electron microscope. The viscoelasticity and viscosity of the slickwater system were evaluated by using rheometer. Finally, based on the D&M formula, the friction calculation model suitable for viscoelastic slickwater system is established and verified with field application. The results showed that the friction reduction performance was improved slightly after the combination of the high friction reduction slickwater and nano-emulsion, and the resistance to salt, shear, and temperature was better; The intersection point of viscoelastic modulus curve moved from 0.47 Hz to 0.10 Hz, and the network structure of the tissue was more well developed, and the law of friction reduction can be could be fitted by the D&M formula; It is found that it has good consistency by fitting the field data through the friction reduction model. It provides theoretical support for the improvement of efficiency, mechanism research, and on-site friction prediction of slickwater system products in the future.
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Zeolites as heterogenous catalysts have continuously attracted researchers’ interest due to the potentials for industrial biomass conversion. However, combining hierarchical structure ...and uniformly dispersed active sites in crystalline zeolites catalysts remains challenging. In this study, in-situ hydrothermal synthesis of Sn-MFI/MCM-41 composites were investigated with hexadecyl trimethylammonium bromide (CTAB) as the structure-directing agent by a stepwise heating. The resulting catalyst was characterized with hexagonal mesochannels, high BET area and crystalline MFI domains. Compared with previously reported tin-containing zeolites, enhanced glucose conversion and fructose selectivity was observed on the resulting Sn-MFI/MCM-41 materials, giving a fructose selectivity of 84%.
•Sn-MFI/MCM-41 composites were hydrothermally prepared.•Temperature-gradient strategy was used to introduce MFI domains into mesoporous framework.•Sn-MFI/MCM-41 composites exhibited excellent catalytic performance for glucose isomerization to fructose.
Capabilities for controlled formation of sophisticated 3D micro/nanostructures in advanced materials have foundational implications across a broad range of fields. Recently developed methods use ...stress release in prestrained elastomeric substrates as a driving force for assembling 3D structures and functional microdevices from 2D precursors. A limitation of this approach is that releasing these structures from their substrate returns them to their original 2D layouts due to the elastic recovery of the constituent materials. Here, a concept in which shape memory polymers serve as a means to achieve freestanding 3D architectures from the same basic approach is introduced, with demonstrated ability to realize lateral dimensions, characteristic feature sizes, and thicknesses as small as ≈500, 10, and 5 µm simultaneously, and the potential to scale to much larger or smaller dimensions. Wireless electronic devices illustrate the capacity to integrate other materials and functional components into these 3D frameworks. Quantitative mechanics modeling and experimental measurements illustrate not only shape fixation but also capabilities that allow for structure recovery and shape programmability, as a form of 4D structural control. These ideas provide opportunities in fields ranging from micro‐electromechanical systems and microrobotics, to smart intravascular stents, tissue scaffolds, and many others.
The use of shape‐memory polymers in mechanically guided formation of 3D structures provides immediate access to freestanding 3D architectures and functional devices across length scales from micrometers to centimeters. The resulting engineering options provide opportunities in fields ranging from micro‐electromechanical systems and microrobotics to smart intravascular stents, tissue scaffolds, and many others.
In order to improve the quality of magnesia flux pellets and meet the production needs of the iron and steel industry, a pellet formation experiment was carried out. The effects of alkalinity R, SiO2 ...mass fraction, MgO mass fraction on the green pellets’ burst temperature, compressive strength, and falling strength were studied. The results showed that with the increase in alkalinity, the bursting temperature of green pellets decreases, but has no obvious effect on the compressive strength or drop strength; with the increase in SiO2 content, the bursting temperature of green pellets decreases gradually, and the green pellets’ strength also decreases slightly; with the increase in MgO content, the compressive strength of green pellets shows an upward trend, while the falling strength gradually decreases, and the burst temperature of green pellets shows a trend of rising first and then decreasing. The change trend is coupled with the software test data amplification method algorithm, based on the search algorithm of longicorn (MBAS), to expand a small amount of experimental data. Through data analysis and algorithm comparison, an improved generalized regression neural network (CFA-GRNN), based on culture firefly, was proposed to establish an optimization model for green pellet performance prediction. CFA uses the weights in the input layer and hidden layer of GRNN, the weights in the hidden layer and output layer, the threshold of the hidden layer and the threshold of the output layer as codes for optimization. The evolutionary goal is to obtain the most appropriate and optimal neural network structure. The results show that the MBAS algorithm, combined with the experimental research, can expand the effective data to 1000 pieces. Secondly, the green pellets’ burst temperature, compressive strength and falling strength predicted by the improved generalized regression neural network are in good agreement with the real values, and the average relative errors were 1.88%, 3.18% and 3.62%, respectively. The error analysis shows that the improved model algorithm has higher accuracy, meets the classification of pellets, and can be used to guide the production of pellets.
Given differences in vulnerability of children in early life, a life course approach to asthma and wheezing (AW) in young children caused by ozone (O3) is not fully understood.
We conducted a birth ...cohort in Jinan, China from 2018 to 2021 to elucidate the onset model of childhood AW due to O3 exposure. An inverse distance weighted model was used for individual exposure assessment. The time-dependent Cox proportional-hazard model and logistic model were used to investigate the effects of O3 exposure on AW. Principal component analysis, interaction analysis, and distributed lag model were used to analyze the life course approach.
The cumulative incidence rate for AW among 6501 children aged 2 was 1.4%. A high level of O3 was related to AW (HR: 2.10, 95% CI: 1.31, 3.37). Only O3 exposure after birth was associated with AW, with an OR of 1.82 (1.08, 3.12), after adjusting for the effect before birth. Furthermore, adjusting for other air pollutants, the HR for the individual effect of high O3 exposure on AW was 2.44 (1.53, 3.89). Interestingly, P values for interactions for O3 and the principal components of other pollutants, as well as the characteristic variable of open windows were less than 0.1. Moreover, an increase in the IQR of O3 exposure at the 31st to 37th weeks before birth and the 1st to 105th weeks after birth was associated with an increase in the HRs for AW.
High-level of O3 exposure after birth could lead to AW among young children. Importantly, the AW onset model may include the risk factors accumulation and the sensitive period model. Specifically, there are two sensitive windows in early life, and the correlated insults between the high level of O3 and other pollutants as well as open windows in the asthma-inducing effect.
•High level of O3 exposure after birth leads to asthma and wheezing (AW) in children aged 0–2.•The AW onset model may include the risk factors accumulation and the sensitive period model.•The sensitive windows were 31st to 37th weeks before birth and 1st to 105th weeks after birth.•There were correlated insults between O3 and other pollutants/open windows in the effect.
Recent evidence indicates that human regulatory T cells (Tregs) are composed of three distinct subpopulations: CD25(++) CD45RA(+) resting Tregs (rTregs), CD25(+++) CD45RA(-) activated Tregs (aTregs), ...which are suppressive, and CD25(++) CD45RA(-) cytokine-secreting (Fr III) cells with pro-inflammatory capacity.
To evaluate the dynamic changes in circulating and pulmonary Treg subpopulations in smokers and patients with chronic obstructive pulmonary disease (COPD), and to explore their potential roles in COPD pathogenesis.
Blood samples were obtained from 57 never-smokers, 32 smokers with normal lung function and 66 patients with COPD. Bronchoalveolar lavage (BAL) samples were taken from 12 never-smokers, 12 smokers and 18 patients with COPD. The proportions of Treg subpopulations and activated CD8 T cells were evaluated using flow cytometry.
In peripheral blood, increased proportions of rTregs, aTregs and Fr III cells were found in smokers compared with never-smokers, whereas patients with COPD showed decreased rTregs and aTregs, and significantly increased Fr III cells compared with smokers. The changes in Treg subpopulations, with an overall decrease in the (aTreg+rTreg):(Fr III) ratio, indicated that immune homeostasis favoured inflammation and correlated with enhanced CD8 T-cell activation (r=-0.399, p<0.001) and forced expiratory volume in 1 s (FEV1) % predicted value (r=0.435, p<0.001).The BAL (aTreg+rTreg):(Fr III) ratios displayed more robust correlations with FEV1% predicted value (r=0.741, p<0.01) and activation of effector T cells (r=-0.763, p<0.001).
The imbalance between the anti-inflammatory subsets (aTreg+rTreg) and the pro-inflammatory subset (Fr III) of Tregs may play an important role in COPD progression.
The buried Daxing Uplift connects the Beijing Sag and Dachang Sag, which is the critical tectonic unit for understanding the structural evolution of the Beijing Sub-plain and its linkages to regional ...tectonics. This study combines paleomagnetic,
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Be isochron dates and sedimentary analyses from a new borehole (Yx02) in the northeastern Beijing Sub-plain to shed fresh light on regional tectonic processes and the sedimentary history since the Pliocene. The main findings are as follows: (1) the Daxing Uplift had formed three depositional episodes: alluvial-fan, lacustrine-delta, and alluvial-fan sedimentation since the Cenozoic; (2) The borehole records the Brunhes, Gauss normal chron, and the Matuyama, Gilbert reversed chron in the Daxing Uplift, the corresponding depths are 0–148.9 m, 148.9–315.0 m, 315.0–520.5 m and 520.5–650 m; (3) An important tectonic event started in ~4.3 Ma, disintegrated NE-trending basin and range terrain, reactivated the NW-trending Nankou-Sunhe fault, and formed Shunyi fault in Beijing Sub-plain. Sedimentation occurs exclusively in the Beijing Sag and the northeastern Daxing Uplift during ~4.3–1.77 Ma; (4) During ~1.77–1.07 Ma, a transition from an extension to a strike-slip occurred, and is described not only in a progressively higher increase of the overall deposition rate, but also in a decrease of the relative deposition disparity between sags and uplifts. Since then, the Beijing Sub-plain has been shaped, associated with an overall subsidence depression in the Bohai Bay Basin. This work enhances our understanding of the formation and evolution of the Beijing Sub-plain, the division of tectonic episodes, and the initiation time of the latest tectonic movement in the break-up region, North China Craton, since the Neogene.
Following the uplift of the Tibet Plateau and the continuous subduction of the Pacific Plate, graben faulting began to appear around the Ordos Block in the Cenozoic. The Hetao Basin is a Cenozoic ...rift basin between the Ordos Block and the Yinshan Mountains, and Late Quaternary sedimentary strata, which have lacustrine facies, are widely distributed inside this basin. However, the evolution of the Hetao Basin and its related fault systems has been debated for a long time due to the lack of tectonic evidence. In this study, four sections named Haolaigou, Bianqianghao, Huhesala, and Hazigai are selected along the north margin of the Hetao Basin. With the lithology and structural analysis of the Upper Pleistocene series in these sections, two new angular unconformities are found within the 10 m thick sedimentary sequence of the lacustrine sediments. Based on the dating results, we speculate that these two upper and lower angular unconformities are formed between 33 ka BP and 40 ka BP, and 60 ka BP and 80 ka BP, respectively. The angular unconformities also provide tectonic constraints for the latest and ongoing tectonic activity in the Quaternary. This tectonic movement begins at around 80 ka BP and causes two different unconformities of the lower strata with varying degrees of deformation (tilt) but also leads to the final death of the ancient lake.
Mobilenet-SSD is a lightweight network with high efficiency, which is widely used in the field of real-time face detection. Whereas, it fails to achieve similar high performances compared to ...region-based CNN methods. In this paper, we propose an improved Mobilenet-SSD approach by optimizing the feature map and the number of prior boxes of the original Mobilenet-SSD. These changes permit the proposed approach to get a high precision and recall in face detection. To assist further with face detection, the method of non-maximum suppression is employed to remove redundant candidate boxes. To evaluate the proposed method, we conduct experiments on the well-known FDDB benchmark dataset. For 300×300 input, the proposed method achieves 91.92% average precision (AP) at 39.0 frames per second (FPS) on GEFORCE GTX 1650. Throughout experimental results, we demonstrate that our approach achieves a considerable improvement on the AP with a slightly degraded speed compared with Mobilenet-SSD. In addition, our approach also outperforms Single Shot MultiBox Detector(SSD) in terms of speed and model size.
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