MEDICAL PHYSICS
·
2019
·Vol. 46
·期 12
·5467-5477
·
IF 3.177
Diya Wang,Yuchao Sang,Xinyu Zhang,Hong Hu,Shukuan Lu,Yu Zhang,Chaoying Fu,Guy Cloutier,Mingxi Wan
Purpose The Nakagami statistical model and Nakagami shape parameter m have been widely used in linear tissue characterization and preliminarily characterized the envelope distributions of nonlinear encapsulated microbubbles (EMBs). However, the Nakagami distribution of nonlinear scattering EMBs lacked a systematical investigation. Thus, this study aimed to investigate the Nakagami distribution of EMBs and illustrate the impact of EMBs' nonlinearity on the Nakagami model. Method A group of simulated EMB phantoms and in vitro EMB dilutions with an increasing concentration distribution under various EMB nonlinearities, as regulated by acoustic parameters, were characterized by using the window-modulated compounding Greenwood–Durand estimator. Results Raw envelope histograms of simulated and in vitro EMBs were well matched with the Nakagami distribution with a high correlation coefficient of 0.965 ± 0.021 ( P < 0.005). The mean values and gradients of m parameters of simulated and in vitro EMBs were smaller than those of linear scatterers due to the stronger nonlinearity. These m values exhibited a quasi-linear improvement with the increase in second harmonic nonlinear-to-linear component ratio regulated by pulse lengths and excitation frequencies at low- and high-concentration conditions. Conclusions The Nakagami distribution was suitable for the EMBs characterization but the corresponding m parameter was affected by the EMBs' nonlinearity. These validations provided support and nonlinear impact assessment for the EMBs' characterization using the Nakagami statistical model in the future.
研究领域:
超声学
·
生物医学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
APPLIED CATALYSIS A-GENERAL
·
2022
·
IF 5.723
Shipei He,Sheng Fan,Kai Yuan,Shujia Guo,Sen Wang,Zhangfeng Qin,Mei Dong,Weibin Fan,Jianguo Wang
Herein, K + was added in the synthesis gel to regulate the distribution of acid sites in the ITQ-13 zeolite and enhance its catalytic performance in the conversion of methanol to olefins (MTO). The results indicate that a proper content of K + ions in the synthesis gel can not only expedite the crystallization of ITQ-13 zeolite, but also significantly decrease the proportion of paired Al and distribute more Al atoms in the 10-ring sinusoidal channel out from the intersection cavity. Accordingly, over the H-ITQ-13(0.3 K) zeolite prepared using the synthesis gel with a KCl/Al 2 O 3 molar ratio of 0.3, the alkene cycle of MTO keeping to the dual cycle hydrocarbon pool (HCP) mechanism is preferably enhanced, whereas the hydride transfer and aromatization reactions are substantially suppressed. As a result, H-ITQ-13(0.3 K) exhibits much longer catalytic lifetime and higher selectivity to propene and butene , in comparison with the H-ITQ-13 counterpart obtained without adding K + .
研究领域:
化学工程
·
催化材料科学
✓ 已验证
DOI
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
·
2019
·
IF 5.589
Pengfei Wu,Yuanyuan Tang,Miao Dang,Siqing Wang,Hangbiao Jin,Yunsong Liu,Hao Jing,Chunmiao Zheng,Shuping Yi,Zongwei Cai
Concerns over the negative impacts of microplastics on human health have led to growing attention on the occurrence of microplastics in aquatic environment. Recent studies have extended their focus from marine to inland waters, especially on the spatial-temporal distribution of the microplastics in urban rivers. In this study, Maozhou River, the largest river in Shenzhen, a tributary of the Pearl River, was selected as a representative inland waterway of Guangdong-Hong Kong-Macao Greater Bay Area. The spatial-temporal investigation was performed on microplastics in the surface water and sediments of 17 sites along the mainstream of the Maozhou River. Results show that microplastics were widely and unevenly distributed along the river and reached the high abundances on the site most intensively surrounded by industries as well as the sites downstream. The abundances in dry season ranged from 4.0 ± 1.0 to 25.5 ± 3.5 items·L −1 in water and 35 ± 15 to 560 ± 70 item·kg −1 in sediments, which were relatively higher than those observed in the wet season (water: 3.5 ± 1.0 to 10.5 ± 2.5 items·L −1 ; sediments: 25 ± 5 to 360 ± 90 item·kg −1 ; p value < 0.05). The dominant types of the microplastics were identified as: PE Polyethylene (PE, water: 45.0%, sediments: 42.0%), polypropylene (PP, water and sediments: 12.5%), polystyrene (PS, water: 34.5%; sediments 14.5%) and polyvinyl chloride (PVC, water: 2.0%; sediments: 15%). Moreover, metals like Al, Si, Ca were discovered on the rough surface of the microplastics, indicating the interactions between the microplastics and the aquatic environment. Through a comprehensive comparison with other major inland waters in China, this work provides valuable data on the microplastics pollution of a representative inland water in the Greater Bay Area, and will further contribute to a better understanding on the land-based input of microplastics from the intensively affected inland waters.
研究领域:
环境科学
·
生态学
✓ 已验证
DOI
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
·
2021
·
IF 7.963
Yang Liu,JinAo You,YuJun Li,JiaoDi Zhang,Yong He,Florian Breider,Shu Tao,WenXin Liu
Studies focused only on surface water may underestimate microplastic abundance in aquatic environments. This was the first survey to investigate the vertical (surface, intermediate, and bottom waters) distribution and composition of microplastics (MPs) in the water columns and surface sediments collected from an urban seagoing river in northern China. Microplastic abundance in the water columns ranged from 5.6 to 31.4 items∙L −1 and from 2141 to 10,035 items∙kg −1 dry weight (dw) in the surface sediments. Polyethylene dominated throughout the water columns to the surface sediments, in which low- and high-density polyethylene (LDPE and HDPE) were dominant in the water columns and surface sediments, respectively. The dominant shape of MPs was fibers/lines in both the water column and the surface sediment samples. Different from the estimations, the average abundance of MPs in the surface and intermediate waters was significantly lower ( p < 0.01) than that in the bottom water, which may be due to the resuspension of small-sized MPs in the bottom water. As the MPs size increased, their vertical distributions in the water columns were more affected by the water depth. The results showed that MPs were detained in the water columns of river system, and the high concentrations of MPs in the bottom water could not be neglected.
研究领域:
环境科学
·
生态学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ADVANCED MATERIALS
·
2023
·Vol. 35
·期 39
·2303674
·
IF 29.4
Wenxiao Zhang,Haobo Yuan,Xiaodong Li,Xuemin Guo,Chunyan Lu,Acan Liu,Hui Yang,Lin Xu,Xueliang Shi,Zhiwei Fang,Haibo Yang,Ya Cheng,Junfeng Fang
Tin-lead (Sn-Pb) perovskite solar cells (PSCs) with near-ideal bandgap still lag behind the pure lead PSCs. Disordered heterojunctions caused by inhomogeneous Sn/Pb ratio in the binary perovskite film induce large recombination loss. Here, an Sn-Pb perovskite film is reported with homogeneous component and energy distribution by introducing hydrazine sulfate (HS) in Sn perovskite precursor. HS can form hydrogen bond network and coordinate with FASnI 3 thus no longer bond with Pb 2+ , which reduces the crystallization rate of tin perovskite to the level of lead analog. The strong bonding between SO 4 2− and Sn 2+ can also suppress its oxidation. As a result, the Sn-Pb PSCs with HS exhibit a significantly improved V OC of 0.91 V along with a high efficiency of 23.17%. Meanwhile, the hydrogen bond interaction network, strong bonding between Sn 2+ and sulfate ion also improve the thermal, storage, and air stability of resulting devices.
研究领域:
材料科学
·
太阳能电池研究
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CONSTRUCTION AND BUILDING MATERIALS
·
2024
·
IF 7.4
Zhipeng Zhu,Xiaoxue Song,Xiang Chi,Jingyao Zhao,Qiaofang Zhou,Antoni Sanchez‑Ferrer,Dengyun Tu,Wanli Cheng
Unilateral surface compression in wood presents notable benefits, including reduced wood volume loss and energy consumption, rendering a highly promising and extensive utilization. However, shortcomings in compressed wood arise due to unclear gas pressure, temperature, and moisture content distribution within the wood during hot pressing. In this paper, the temperature and pressure distribution were analyzed utilizing an optical fiber temperature and pressure measurement system within the wood during hot pressing. Moreover, the moisture content, stress and strain in each layer at the end of hot pressing were discussed extensively. The results showed that the wood surface layer (SL) and subsurface layer (SSL) maximum temperature values were similar even with different layer thicknesses. Under sealing conditions, SL and SSL temperatures were generally 6 ℃ to 7 ℃ higher compared to unsealing conditions. The gas pressure maximum value exhibited an opposite order, gradually transferring to the core layer (CL) and declining as the processing time extended. During compression treatment, moisture migrated from the hot end to the cold within the wood. The moisture content displayed significant differences between the middle and end parts of the wood under unsealed conditions, with the disparity becoming more pronounced further away from the hot end. The transition region of the compressed wood served as a stress concentration area, experiencing the highest levels of stress. The dense region followed with the second highest stress levels, while the un-densified region exhibited the least amount of stress. Under the same process parameters, the thickness had little influence on the distribution of dense layers.
研究领域:
木材科学
·
材料科学
✓ 已验证
DOI
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
·
2021
·
IF 10.588
Feilong Dong,Zhen Pang,Jianquan Yu,Jing Deng,Xueyan Li,Xiaoyan Ma,Andrea M. Dietrich,Yang Deng
Distributions of halogenated disinfection byproducts (DBPs) in a two-source water distribution system (WDS) with enhanced chlorination were investigated. The WDS was divided into different sub-service areas based on different electrical conductivity of two water sources. Results clearly show that the principal halogenated DBPs were trihalomethanes (THMs) (5.06–82.69 μg/L), varying within the concentration range as 2–5 times as the levels of haloacetic acids (HAAs) (1.41–61.48 μg/L) and haloacetonitriles (HANs) (0.21–15.13 μg/L). Different water sources, treatment trains, and enhanced chlorination within the WDS had significant effects on seasonal and spatial variations of the DBP distributions over water conveyance. THM and HAA formation followed the sequence of summer > autumn > winter > spring. On the other hand, the DBP spatial distributions were visualized using the ArcGIS enabled Inverse distance weighting technique. The superposition of different DBP spatial distributions allowed for the identification of the high-risk THMs and HAAs areas based on the average values of THMs (27.49 μg/L) and HAAs (14.06 μg/L). Beyond the comprehensive analyses of DBP distribution in a municipal WDS , the project proposed and validated an innovative methodology to locate the DBP high-risk areas and to reveal the effects of different factors on DBPs distribution in a two-source WDS.
研究领域:
环境科学
·
公共卫生
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CRYSTENGCOMM
·
2020
·Vol. 22
·期 36
·6019-6025
·
IF 3.117
Junli Wang,Fan Guan,Lijun Zhao,Longhua Li,Junhao Zhang,Tingting Wang
Composition engineering is an active topic of research for optical and electronic (nano)crystals and functional materials. We here demonstrate the control over the ratios and distributions of selenium and sulfur in ternary Sb2(Se,S)3 alloy nanorods (NRs), which were synthesized from a molecular chalcogen precursor, selenium disulfide (SeS2). By increasing the anion/cation precursor ratios (SeS2/SbCl3) from 0.5 : 1 to 1 : 1 and 1.5 : 1, an increase in both the Se fractions and the lengths × diameters of NRs is achieved with the Se and S distributions in Sb2(Se,S)3 varying from homogeneity to inhomogeneity. Within the inhomogeneous NRs obtained at high SeS2/SbCl3 ratios containing excessive chalcogen (Se + S), S decreases but Se increases from the center to the periphery as revealed by EDS elemental analyses performed on individual NRs. In particular, the 1D growth anisotropy of NRs allows for a large chalcogen concentration gradient along the axial direction of the resulting NRs from their middle to the two ends. Such non-uniform Se and S distributions can be rationally interpreted by analyzing the growth kinetics and processes of Sb2(Se,S)3 NRs and would give rise to uncommon (opto)electronic properties towards future nanowire-based devices.
研究领域:
材料科学
·
纳米技术
✓ 已验证
DOI
高影响因子
Scientific Reports
·
2018
·Vol. 8
·期 1
·1-9
·
IF 4.122
Zhu Yun,Hu Xueping,Pan Dawei,Han Haitao,Lin Mingyue,Lu Yan,Wang Chenchen,Zhu Rilong
In this study, the speciation of iron (Fe), including total Fe (TFe) and acidified dissolved Fe (ADFe), was assessed by fast cathodic absorption stripping voltammetry, using a gold electrode and 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) as a novel complexing agent for Fe. The validity and accuracy of this method were compared with the standard spectrophotometry and tested by the standard samples. Under optimized conditions, the Fe response was linear within the range of 0.01 to 1 μM with a detection limit of 1.2 nM. To further validate this method, the variation in concentrations of TFe and ADFe were investigated at twelve sampling stations in a local coastal river, in both the dry and wet season. Additionally, to further understand the interaction between Fe and environmental factors, the relationships between the concentration of Fe species and dissolved oxygen (DO) and salinity were also discussed.
研究领域:
环境科学
·
分析化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
MACROMOLECULES
·
2025
·
IF 5.2
Shilong Wu,Huanhuan Yang,Quan Chen
In this study, we investigated the effect(s) of side-chain length distribution on the transient elongational hardening behavior of polymer melts. For either entangled or unentangled systems, we successfully prepared a series of samples, poly(butyl methacrylate), poly(methyl methacrylate-co-hexyl methacrylate), and poly(methyl methacrylate-co-lauryl methacrylate), abbreviated as PBMA, P(MMA-co-HMA), and P(MMA-co-LMA), respectively, that have the same average length of side chains and similar weight-average molecular weight. These samples exhibited quite different nonlinear elongational behavior despite a similarity of their linear viscoelastic behavior. The transient strain hardening is enhanced on an increase of the side-chain length distribution, namely, in the order of PBMA < P(MMA-co-HMA) < P(MMA-co-LMA), consistently for either the unentangled or entangled series. Given this consistency, the detailed hardening behavior is different, where the unentangled samples exhibit thickening at the Rouse Weissenberg number WiR > 0.1 and thinning at the higher WiR > 1, which can be explained by a combination of the finite extensional nonlinear elasticity and the frictional reduction when chains are highly stretched and coaligned. The degree of friction reduction relies on the length distribution according to the interpenetration of side chains. In comparison, the entangled samples exhibit consistent thinning even when WiR is lower than one, which is attributable to the concurrence of the flow-induced disentanglement.
研究领域:
高分子物理
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
POLYMER COMPOSITES
·
2023
·
IF 5.2
Bo-Wen Guan,Yuan-Yuan Zhang,Yuan-Qing Li,Shao-Yun Fu
According to the recommendations of literature and standards, the minimum sample size for the friction test of thermoplastics is usually 3–5. While this size is valid for the friction test of neat polymer resins with homogeneous structures, its applicability to short fiber reinforced polymer composites with inhomogeneous structures remains unclear because the uneven distribution of discontinuous fibers or fillers in the matrix leads to the performance of the composites being dispersed. In this work, as a typical example, 100 friction samples made of short carbon fiber reinforced polyetherimide (SCF/PEI) composite with a typical content of 10 vol% SCFs are prepared, and their friction coefficients are measured. The maximum likelihood estimation and goodness of fit methods are employed to assess the fitting degree between the overall friction coefficient results and five mathematical distributions. The results show that the overall friction coefficient data distribution is in good agreement with the Lognormal, Generalized extreme value (GEV), and Burr distributions, respectively. Based on the fitting result, the minimum sample size is analyzed by Monte Carlo Simulation. It shows that the minimum sample size strongly depends on the property dispersion parameter (COV: coefficient of variation). Based on this parameter, the minimum sample size is given. In a practical test, the performance dispersion degree of a composite cannot be known in advance, hence a sample size determination method is proposed to yield a reasonable performance description parameter by applying the results of this work, and this method is validated by the overall test data. Highlights Proposed a sample size determination method for practical friction tests. The minimum sample size for the friction test is yielded statistically. The minimum sample size strongly depends on a property dispersion parameter.
研究领域:
材料科学
·
机械工程
·
统计学
✓ 已验证
产品关联
DOI
高影响因子
ENVIRONMENTAL SCIENCE & TECHNOLOGY
·
2024
·
IF 10.8
Qian Bao,Yi Yang,Dahang Shen,Feiyang Ye,Jiageng Yu,Osama Alam,Wei Wang
Decabromodiphenyl ethane (DBDPE), a key alternative to deca-BDE (BDE-209), has been ubiquitous in the receiving ecosystem. However, little is known about its uptake process and fate in plants. Here, the plant absorption, distribution, and metabolism of 14C-DBDPE under two distinct exposure pathways (i.e., soil-root and airborne dust-leaf) were investigated with three vegetables (cherry radish, water spinach, and eggplant). DBDPE was absorbed and primarily accumulated in directly exposed roots and leaves, with translocation factors to other tissues of 0.04–0.77 and 0.73–12.80 × 10–3, respectively. DBDPE in exposed leaves was more difficult to transport as most DBDPE did not enter the interior of the leaves but was stored in waxes (>90%). Furthermore, DBDPE within leaves was found to enter mostly through waxy layer penetration (>97%). The majority of 14C-DBDPE was localized in cell walls (52.6 and 75.6%, respectively) and organelles (22.7 and 45.5%, respectively) of exposed tissues, substantially restricting its in-plant translocation. Debrominated products were detected in exposed roots, but barely found in exposed leaves, as most DBDPE was blocked by the waxy layer. Moreover, DBDPE was stable in soils and dust without degradation. Our findings contribute to a deeper understanding of the environmental fate of DBDPE in soil-plant and airborne dust-plant systems.
研究领域:
环境科学
·
植物学
✓ 已验证
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）