Publications by authors named "Zhijun Wu"

182 Publications

Barrierless HONO and HOS(O)2-NO Formation via NH-Promoted Oxidation of SO by NO.

J Phys Chem A 2021 Apr 23;125(12):2666-2672. Epub 2021 Mar 23.

State Key Joint Laboratory of Environment Simulation and Pollution Control (Peking University), College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.

In the troposphere, the knowledge about nitrous acid (HONO) sources is incomplete. The missing source of sulfate and fine particles cannot be explained during haze events. Air quality models cannot predict high levels of secondary fine-particle pollution. Despite extensive studies, one challenging issue in atmospheric chemistry is identifying the source of HONO. Here, we present direct ab initio molecular dynamics simulation evidence and typical air pollution events of the formation of gaseous HONO, nitrogen dioxide/hydrogen sulfite (HOS(O)2-NO or NO-HSO) from nitrogen dioxide (NO), sulfur dioxide (SO), water (HO), and ammonia (NH) molecules in a proportion of 2:1:3:3. The reactions show a new mechanism for the formation of HONO and NO-HSO in the troposphere, especially when the concentration of NO, SO, HO, and NH is high (e.g., 2:1:3:3 or higher) in the air. Contrary to the proportion NO, SO, HO, and NH equaling to 1:1:3:1 and 1:1:3:2, the proportion (2:1:3:3) enables barrierless reactions and weak interactions between molecules via the formation of HONO, NO-HSO, and NH/HO. In addition, field observations are carried out, and the measured data are summarized. Correlation analysis supported the conversion of NO to HONO during observational studies. The weak interactions promote proton transfer, resulting in the generation of HONO, NO-HSO, and NH/HO pairs.
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http://dx.doi.org/10.1021/acs.jpca.1c00539DOI Listing
April 2021

Larger than expected variation range in the real part of the refractive index for ambient aerosols in China.

Sci Total Environ 2021 Mar 14;779:146443. Epub 2021 Mar 14.

Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing 100871, China.

The real part of the refractive index (RRI) of ambient aerosol, which is widely used in remote sensing and atmospheric models, is one of the key factors determining its particles' optical properties. The characteristics of ambient aerosol RRI in China have not yet been well studied owing to a lack of observations. For the first time, the properties of aerosol RRI were studied based on field measurements in China at four sites with different atmospheres. The results revealed that the measured ambient aerosol RRI varied significantly between 1.36 and 1.78, increasing with the mass ratio of organic components. The scattering coefficient and direct radiative effects of the aerosols were estimated to increase by factors of 2 and 3, respectively, when RRI increased from 1.36 to 1.78. Our results indicate that variation in ambient aerosol RRI should be considered in aerosol and climate models to achieve an accurate estimation of aerosol's radiative impacts.
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http://dx.doi.org/10.1016/j.scitotenv.2021.146443DOI Listing
March 2021

All-Dielectric Color Filter with Ultra-Narrowed Linewidth.

Micromachines (Basel) 2021 Feb 27;12(3). Epub 2021 Feb 27.

College of Optical and Electronic Technology, China Jiliang University, Hangzhou 310018, China.

In this paper, a transmissive color filter with an ultra-narrow full width at half of the maximum is proposed. Exploiting a material with a high index of refraction and an extremely low extinction coefficient in the visible range allows the quality factor of the filter to be improved. Three groups of GaP/SiO pairs are used to form a Distributed Brag reflector in a symmetrical Fabry-Pérot cavity. A band-pass filter which is composed of ZnS/SiO pairs is also introduced to further promote the purity of the transmissive spectrum. The investigation manifests that a series of tuned spectrum with an ultra-narrow full width at half of the maximum in the full visible range can be obtained by adjusting the thickness of the SiO interlayer. The full width at half of the maximum of the transmissive spectrum can reach 2.35 nm. Simultaneously, the transmissive efficiency in the full visible range can keep as high as 0.75. Our research provides a feasible and cost-effective way for realizing filters with ultra-narrowed linewidth.
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http://dx.doi.org/10.3390/mi12030241DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7997520PMC
February 2021

Steganography and Steganalysis in Voice over IP: A Review.

Sensors (Basel) 2021 Feb 3;21(4). Epub 2021 Feb 3.

School of Electronics & Information & Automation, Civil Aviation University of China, Tianjin 300300, China.

The rapid advance and popularization of VoIP (Voice over IP) has also brought security issues. VoIP-based secure voice communication has two sides: first, for legitimate users, the secret voice can be embedded in the carrier and transmitted safely in the channel to prevent privacy leakage and ensure data security; second, for illegal users, the use of VoIP Voice communication hides and transmits illegal information, leading to security incidents. Therefore, in recent years, steganography and steganography analysis based on VoIP have gradually become research hotspots in the field of information security. Steganography and steganalysis based on VoIP can be divided into two categories, depending on where the secret information is embedded: steganography and steganalysis based on voice payload or protocol. The former mainly regards voice payload as the carrier, and steganography or steganalysis is performed with respect to the payload. It can be subdivided into steganography and steganalysis based on FBC (fixed codebook), LPC (linear prediction coefficient), and ACB (adaptive codebook). The latter uses various protocols as the carrier and performs steganography or steganalysis with respect to some fields of the protocol header and the timing of the voice packet. It can be divided into steganography and steganalysis based on the network layer, the transport layer, and the application layer. Recent research results of steganography and steganalysis based on protocol and voice payload are classified in this paper, and the paper also summarizes their characteristics, advantages, and disadvantages. The development direction of future research is analyzed. Therefore, this research can provide good help and guidance for researchers in related fields.
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http://dx.doi.org/10.3390/s21041032DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7913304PMC
February 2021

Explosive Secondary Aerosol Formation during Severe Haze in the North China Plain.

Environ Sci Technol 2021 Feb 4;55(4):2189-2207. Epub 2021 Feb 4.

Department of Atmospheric Sciences, Texas A&M University, College Station, Texas 77843, United States.

Severe haze events with exceedingly high-levels of fine aerosols occur frequently over the past decades in the North China Plain (NCP), exerting profound impacts on human health, weather, and climate. The development of effective mitigation policies requires a comprehensive understanding of the haze formation mechanisms, including identification and quantification of the sources, formation, and transformation of the aerosol species. Haze evolution in this region exhibits distinct physical and chemical characteristics from clean to polluted periods, as evident from increasing stagnation and relative humidity, but decreasing solar radiation as well as explosive secondary aerosol formation. The latter is attributed to highly elevated concentrations of aerosol precursor gases and is reflected by rapid increases in the particle number and mass concentrations, both corresponding to nonequilibrium chemical processes. Considerable new knowledge has been acquired to understand the processes regulating haze formation, particularly in light of the progress in elucidating the aerosol formation mechanisms. This review synthesizes recent advances in understanding secondary aerosol formation, by highlighting several critical chemical/physical processes, that is, new particle formation and aerosol growth driven by photochemistry and aqueous chemistry as well as the interaction between aerosols and atmospheric stability. Current challenges and future research priorities are also discussed.
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http://dx.doi.org/10.1021/acs.est.0c07204DOI Listing
February 2021

Porcine epidemic diarrhea virus E protein suppresses RIG-I signaling-mediated interferon-β production.

Vet Microbiol 2021 Mar 15;254:108994. Epub 2021 Jan 15.

College of Animal Science and Veterinary Medicine, HeiLongJiang BaYi Agricultural University, Daqing, 163319, China; College of Life Science and Technology, HeiLongJiang BaYi Agricultural University, Daqing, 163319, China; Biotechnology Center, HeiLongJiang BaYi Agricultural University, Daqing, 163319, China. Electronic address:

Porcine epidemic diarrhea virus (PEDV) encodes many multifunctional proteins that inhibit host innate immune response during virus infection. As one of important structural proteins, PEDV E protein has been found to block the production of type I interferon (IFN) in virus life cycle, but little is known about this process that E protein subverts host innate immune. Thus, in this present study, we initiated the construction of eukaryotic expression vectors to express PEDV E protein. Subsequently, cellular localization analysis was performed and the results showed that the majority of PEDV E protein distributed at cytoplasm and localized in endoplasmic reticulum (ER). Over-expression of PEDV E protein significantly inhibited poly(I:C)-induced IFN-β and IFN-stimulated genes (ISGs) productions. We also found that PEDV E protein remarkably suppressed the protein expression of RIG-I signaling-associated molecules, but all their corresponding mRNA levels remained unaffected and unchanged. Furthermore, PEDV E protein obviously interfered with the translocation of IRF3 from cytoplasm to nucleus through direct interaction with IRF3, which is crucial for the IFN-β production induced by poly(I:C). Taken together, our results suggested that PEDV E protein acts as an IFN-β antagonist through suppression of the RIG-I-mediated signaling. This study will pave the way for the further investigation into the molecular mechanisms by which PEDV E protein evades host innate immune response.
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http://dx.doi.org/10.1016/j.vetmic.2021.108994DOI Listing
March 2021

Backpropagation neural network assisted concentration prediction of biconical microfiber sensors.

Opt Express 2020 Dec;28(25):37566-37576

The response of the optical microfiber sensor has a big difference due to the slight change in fiber structure, which greatly reduces the reliability of microfiber sensors and limits its practical applications. To avoid the nonlinear influences of microfiber deformation and individual differences on sensing performance, a backpropagation neural network (BPNN) is proposed for concentration prediction based on biconical microfiber (BMF) sensors. Microfiber diameter, cone angle, and relative intensity are the key input parameters for detecting the concentration of chlorophyll-a (from ∼0.03 mg/g to ∼0.10 mg/g). Hundreds of relative intensity-concentration data pairs acquired from 32 BMF sensors are used for the network training. The prediction ability of the model is evaluated by the root-mean-square error (RMSE) and the fitness value (F). The prediction performance of BPNN is compared with the traditional linear-fitting line method. After training, BPNN could adapt to the BMF sensors with different structural parameters and predict the nonlinear response caused by the small structural changes of microfiber. The concentration prediction given by BPNN is much closer to the actual measured value than the one obtained by the linear fitting curve (RMSE 1.84×10 mg/g vs. 4.6×10 mg/g). The numbers of training data and hidden layers of the BPNN are discussed respectively. The prediction results indicate that the one-hidden-layer network trained by more training data provides the best performance (RMSE and fitness values are 1.63×10 mg/g and 97.91%, respectively) in our experiments. With the help of BPNN, the performance of the BMF sensor is acceptable to the geometric deformation and fabrication error of microfiber, which provides an opportunity for the practical application of sensors based on micro/nanofibers.
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http://dx.doi.org/10.1364/OE.411246DOI Listing
December 2020

Humidity-Dependent Phase State of Gasoline Vehicle Emission-Related Aerosols.

Environ Sci Technol 2021 01 30;55(2):832-841. Epub 2020 Dec 30.

State Key Joint Laboratory of Environmental Simulation and Pollution Control, International Joint Laboratory for Regional Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.

The phase states of primarily emitted and secondarily formed aerosols from gasoline vehicle exhausts were investigated by quantifying the particle rebound fraction (). The rebound behaviors of gasoline vehicle emission-related aerosols varied with engines, fuel types, and photochemical aging time, showing distinguished differences from biogenic secondary organic aerosols. The nonliquid-to-liquid phase transition of primary aerosols emitted from port fuel injection (PFI) and gasoline direct injection (GDI) vehicles started at a relative humidity (RH) = 50 and 60%, and liquefaction was accomplished at 60 and 70%, respectively. The RH at which declined to 0.5 decreased from 70 to 65% for the PFI case with 92# fuel, corresponding to the photochemical aging time from 0.37 to 4.62 days. For the GDI case, such RH enhanced from 60 to 65%. Our results can be used to imply the phase state of traffic-related aerosols and further understand their roles in urban atmospheric chemistry. Taking Beijing, China, as an example, traffic-related aerosols were mainly nonliquid during winter with the majority ambient RH below 50%, whereas they were mostly liquid during the morning rush hour of summer, and traffic-related secondary aerosols fluctuated between nonliquid and liquid during the daytime and tended to be liquid at night with increased ambient RH.
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http://dx.doi.org/10.1021/acs.est.0c05478DOI Listing
January 2021

P2Y inhibitor monotherapy and dual antiplatelet therapy after percutaneous coronary intervention: An updated meta-analysis of randomized trials.

Thromb Res 2021 Feb 7;198:115-121. Epub 2020 Dec 7.

Department of Cardiology, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, People's Republic of China. Electronic address:

Introduction: Long-term dual antiplatelet therapy (DAPT) has substantially reduced the risk of post-percutaneous coronary intervention (PCI) myocardial infarction and stent thrombosis at the expense of major bleeding. We hypothesized that a short-term DAPT followed by extended P2Y inhibitor monotherapy might be appropriate for patients with both high ischemic and bleeding risks.

Materials And Methods: We searched the databases: Pubmed, EMBASE, Cochrane Central Register of Controlled Trials and ClinicalTrials.gov to identify randomized trials assessing the antiplatelet strategies after PCI. The primary safety endpoint was Bleeding Academic Research Consortium (BARC) type 3 or 5 bleeding. The efficacy outcome was a composite of all-cause mortality/cardiovascular disease (CVD) death, myocardial infarction, or stroke. A random-effect model was used to calculate the pooled hazard ratios (HRs) with 95% confidence intervals (CIs).

Results: We identified 5 randomized trials comparing P2Y inhibitor monotherapy with standard DAPT (12 months) (16,057 versus 16,088). P2Y inhibitor monotherapy following short-term DAPT (1 to 3 months) significantly reduced the risk of BARC type 3 or 5 bleeding compared to standard DAPT (pooled HR: 0.63, 95%CI: 0.46-0.86). The difference between P2Y inhibitor monotherapy and standard DAPT in reducing the composite CVD outcomes was not statistically significant (HR: 0.88, 95%CI: 0.77-1.01).

Conclusions: P2Y inhibitor monotherapy might be an effective strategy for lowering severe bleeding complications and simultaneously preserving the ischemic benefit in patients receiving PCI.
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http://dx.doi.org/10.1016/j.thromres.2020.11.038DOI Listing
February 2021

Overview of biological ice nucleating particles in the atmosphere.

Environ Int 2021 Jan 30;146:106197. Epub 2020 Nov 30.

Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China. Electronic address:

Biological particles in the Earth's atmosphere are a distinctive category of ice nucleating particles (INPs) due to their capability of facilitating ice crystal formation in clouds at relatively warm temperatures. Field observations and model simulations have shown that biological INPs affect cloud and precipitation formation and regulate regional or even global climate, although there are considerable uncertainties in modeling and large gaps between observed and model simulated contribution of biological particles to atmospheric INPs. This paper overviews the latest researches about biological INPs in the atmosphere. Firstly, we describe the primary ice nucleation mechanisms, and measurements and model simulations of atmospheric biological INPs. Secondly, we summarize the ice nucleating properties of biological INPs from diverse sources such as soils or dust, vegetation (e.g., leaves and pollen grains), sea spray, and fresh waters, and controlling factors of biological INPs in the atmosphere. Then we review the abundance and distribution of atmospheric biological INPs in diverse ecosystems. Finally, we discuss the open questions in further studies on atmospheric biological INPs, including the requirements for developing novel detection techniques and simulation models, as well as the comprehensive investigation of characteristics and influencing factors of atmospheric biological INPs.
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http://dx.doi.org/10.1016/j.envint.2020.106197DOI Listing
January 2021

Neuroprotective effects of microRNA-140-5p on ischemic stroke in mice via regulation of the TLR4/NF-κB axis.

Brain Res Bull 2021 Mar 24;168:8-16. Epub 2020 Nov 24.

Department of Neurology, The Second Affiliated Hospital of Lanzhou University, Lanzhou, 730030, PR China.

Background And Aim: Ischemic stroke is one of the main causes of death worldwide and permanent global disability. On the basis of existing literature data, the study was carried out in an effort to explore how miR-140-5p affects ischemic stroke and whether the mechanism relates to toll-like receptor-4 (TLR4) and nuclear factor-kappa B (NF-κB).

Methods: Firstly, middle cerebral artery occlusion (MCAO) was performed to establish mouse models of ischemic stroke in vivo, while primary neurons were exposed to oxygen-glucose deprivation (OGD) to set up an ischemic stroke model in vitro. RT-qPCR was then applied to detect the miR-140-5p expression patterns, whereas Western blot was adopted to detect the expression patterns of TLR4, NF-κB, and apoptosis-related factors. In addition, based gain-function of experiments using miR-140-5p mimic and TLR4 over-expression plasmid, neurological function score, TTC staining, TUNEL staining, as well as flow cytometry were carried out to evaluate the effects of miR-140-5p and TLR4 on MCAO mice and OGD neurons. Moreover, dual-luciferase reporter assay was applied to validate the targeting relationship between miR-140-5p and TLR4.

Results: Initial findings revealed that miR-140-5p was poorly-expressed, while TLR4 was highly-expressed in ischemic stroke. It was verified that miR-140-5p targeted TLR4 and downregulated its expression. MiR-140-5p over-expression was observed to inhibit the apoptosis of neurons under OGD exposure and restrain the progression of ischemic stroke, while TLR4 over-expression promoted the apoptosis and disease progression. Besides, miR-140-5p over-expression led to a decrease in NF-κB protein levels, which were increased by TLR4 over-expression.

Conclusion: In conclusion, our data indicates that miR-140-5p over-expression may be instrumental for the therapeutic targeting of ischemic stroke by alleviating neuron injury with the involvement of the TLR4/NF-κB axis.
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http://dx.doi.org/10.1016/j.brainresbull.2020.10.020DOI Listing
March 2021

Avoiding high ozone pollution in Delhi, India.

Faraday Discuss 2021 Mar 27;226:502-514. Epub 2020 Nov 27.

Lancaster Environment Centre, Lancaster University, Lancaster, UK.

Surface ozone is a major pollutant threatening public health, agricultural production and natural ecosystems. While measures to improve air quality in megacities such as Delhi are typically aimed at reducing levels of particulate matter (PM), ozone could become a greater threat if these measures focus on PM alone, as some air pollution mitigation steps can actually lead to an increase in surface ozone. A better understanding of the factors controlling ozone production in Delhi and the impact that PM mitigation measures have on ozone is therefore critical for improving air quality. Here, we combine in situ observations and model analysis to investigate the impact of PM reduction on the non-linear relationship between volatile organic compounds (VOC), nitrogen oxides (NO) and ozone. In situ measurements of NO, VOC, and ozone were conducted in Delhi during the APHH-India programme in summer (June) and winter (November) 2018. We observed hourly averaged ozone concentrations in the city of up to 100 ppbv in both seasons. We performed sensitivity simulations with a chemical box model to explore the impacts of PM on the non-linear VOC-NO-ozone relationship in each season through its effect on aerosol optical depth (AOD). We find that ozone production is limited by VOC in both seasons, and is particularly sensitive to solar radiation in winter. Reducing NO alone increases ozone, such that a 50% reduction in NO emissions leads to 10-50% increase in surface ozone. In contrast, reducing VOC emissions can reduce ozone efficiently, such that a 50% reduction in VOC emissions leads to ∼60% reduction in ozone. Reducing PM alone also increases ozone, especially in winter, by reducing its dimming effects on photolysis, such that a 50% reduction in AOD can increase ozone by 25% and it also enhances VOC-limitation. Our results highlight the importance of reducing VOC emissions alongside PM to limit ozone pollution, as well as benefitting control of PM pollution through reducing secondary organic aerosol. This will greatly benefit the health of citizens and the local ecosystem in Delhi, and could have broader application for other megacities characterized by severe PM pollution and VOC-limited ozone production.
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http://dx.doi.org/10.1039/d0fd00079eDOI Listing
March 2021

Investigations on a mathematical model for optimum impedance compensation of a giant magnetostrictive ultrasonic transducer and its resonance characteristics.

Ultrasonics 2021 Feb 20;110:106286. Epub 2020 Oct 20.

Beijing Key Lab of Precision/Ultra-precision Manufacturing Equipments and Control, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China.

Giant magnetostrictive materials (GMMs) have been widely used to fabricate transducers with high-energy output because of their excellent properties. However, there are few reports on mathematical models to optimize the impedance compensation and resonance characteristics of giant magnetostrictive transducers. In this study, a giant magnetostrictive ultrasonic transducer (GMUT) suitable for rotary ultrasonic machining systems is proposed. A mathematical model for optimum impedance compensation that considers the loss in energy conversion is established to maximize the use of ultrasonic energy. The frequency characteristics of the electrical feedback signal in the resonance state are investigated, and the resonance zone found is used for frequency tracking. An impedance analyzer is used to determine the parameters of the mathematical model, and the validity of the optimum compensation capacitance is verified by experiments. The frequency characteristics of the minimum current, active power, and amplitude are obtained to obtain the resonance zone in the GMUT with the lowest energy consumption. The results of this study provide a reference for frequency tracking.
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http://dx.doi.org/10.1016/j.ultras.2020.106286DOI Listing
February 2021

Vertical profile of particle hygroscopicity and CCN effectiveness during winter in Beijing: insight into the hygroscopicity transition threshold of black carbon.

Faraday Discuss 2021 Mar 26;226:239-254. Epub 2020 Nov 26.

School of Earth and Environmental Sciences, University of Manchester, UK.

The hygroscopicity and ability of aerosol particles to act as cloud condensation nuclei (CCN) is important in determining their lifetime and role in aerosol-cloud interactions, thereby influencing cloud formation and climate. Previous studies have used the aerosol hygroscopic properties measured at the ground to evaluate the influence on cloud formation in the atmosphere, which may introduce uncertainty associated with aerosol hygroscopicity variability with altitude. In this study, the CCN behaviour and hygroscopic properties of daily filter collections of PM from three different heights (8, 120, 260 m) on a tower in Beijing were determined in the laboratory using water, water/methanol and methanol as the atomization solvents. Whilst there was substantial temporal variability in particle concentration and composition, there was little obvious difference in aerosol CCN and hygroscopic behaviour at different heights, although the planetary boundary layer height (PBLH) reduced to below the tower height during the nighttime, suggesting that use of surface hygroscopicity measurements is sufficient for the estimation of aerosol particle activation in clouds. Additionally, the critical coating thickness (in terms of mass ratio of coating/refractory BC, MRc) defining the BC transition between being hydrophobic to hydrophilic, was determined by combining hygroscopic tandem differential mobility analyser (H-TDMA), centrifugal particle mass analyzer (CPMA) and single particle soot photometer (SP2) measurements. The MRc of 250 nm BC-containing particles increased from a background value of between 0.8 and 1.6 to around 4.6 at the onset of the growth event of nanoparticles, decreasing monotonically back to the background level as the event progressed. This indicates that large particles do not act as an effective pre-existing condensation sink of the hygroscopic vapours during the nanoparticle growth events, leading to the 250 nm BC particles requiring more coating materials to transition between being hydrophobic and hydrophilic. These findings show that large particles may be less important in suppressing the new particle formation and subsequent growth in the atmosphere.
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http://dx.doi.org/10.1039/d0fd00077aDOI Listing
March 2021

Risk stratification for mortality in cardiovascular disease survivors: A survival conditional inference tree analysis.

Nutr Metab Cardiovasc Dis 2021 02 3;31(2):420-428. Epub 2020 Oct 3.

Department of Nutritional Sciences, Pennsylvania State University, State College, PA, USA. Electronic address:

Background And Aims: Efficient analysis strategies for complex network with cardiovascular disease (CVD) risk stratification remain lacking. We sought to identify an optimized model to study CVD prognosis using survival conditional inference tree (SCTREE), a machine-learning method.

Methods And Results: We identified 5379 new onset CVD from 2006 (baseline) to May, 2017 in the Kailuan I study including 101,510 participants (the training dataset). The second cohort composing 1,287 CVD survivors was used to validate the algorithm (the Kailuan II study, n = 57,511). All variables (e.g., age, sex, family history of CVD, metabolic risk factors, renal function indexes, heart rate, atrial fibrillation, and high sensitivity C-reactive protein) were measured at baseline and biennially during the follow-up period. Up to December 2017, we documented 1,104 deaths after CVD in the Kailuan I study and 170 deaths in the Kailuan II study. Older age, hyperglycemia and proteinuria were identified by the SCTREE as main predictors of post-CVD mortality. CVD survivors in the high risk group (presence of 2-3 of these top risk factors), had higher mortality risk in the training dataset (hazard ratio (HR): 5.41; 95% confidence Interval (CI): 4.49-6.52) and in the validation dataset (HR: 6.04; 95%CI: 3.59-10.2), than those in the lowest risk group (presence of 0-1 of these factors).

Conclusion: Older age, hyperglycemia and proteinuria were the main predictors of post-CVD mortality.

Trial Registration: ChiCTR-TNRC-11001489.
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http://dx.doi.org/10.1016/j.numecd.2020.09.029DOI Listing
February 2021

DeepLRHE: A Deep Convolutional Neural Network Framework to Evaluate the Risk of Lung Cancer Recurrence and Metastasis From Histopathology Images.

Front Genet 2020 25;11:768. Epub 2020 Aug 25.

Baotou Cancer Hospital, Baotou, China.

It is critical for patients who cannot undergo eradicable surgery to predict the risk of lung cancer recurrence and metastasis; therefore, the physicians can design the appropriate adjuvant therapy plan. However, traditional circulating tumor cell (CTC) detection or next-generation sequencing (NGS)-based methods are usually expensive and time-inefficient, which urge the need for more efficient computational models. In this study, we have established a convolutional neural network (CNN) framework called DeepLRHE to predict the recurrence risk of lung cancer by analyzing histopathological images of patients. The steps for using DeepLRHE include automatic tumor region identification, image normalization, biomarker identification, and sample classification. In practice, we used 110 lung cancer samples downloaded from The Cancer Genome Atlas (TCGA) database to train and validate our CNN model and 101 samples as independent test dataset. The area under the receiver operating characteristic (ROC) curve (AUC) for test dataset was 0.79, suggesting a relatively good prediction performance. Our study demonstrates that the features extracted from histopathological images could be well used to predict lung cancer recurrence after surgical resection and help classify patients who should receive additional adjuvant therapy.
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http://dx.doi.org/10.3389/fgene.2020.00768DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7477356PMC
August 2020

Lipid raft-associated PI3K/Akt/SREBP1 signaling regulates coxsackievirus A16 (CA16) replication.

Vet Microbiol 2021 Jan 5;252:108921. Epub 2020 Nov 5.

College of Life Science and Technology, HeiLongJiang BaYi Agricultural University, Daqing 163319, China; College of Animal Science and Veterinary Medicine, HeiLongJiang BaYi Agricultural University, Daqing 163319, China; Biotechnology Center, HeiLongJiang BaYi Agricultural University, Daqing 163319, China. Electronic address:

Coxsackievirus A16 (CA16) is one of predominant Enterovirus that possesses high pathogenicity. Lipid rafts, as cholesterol - and sphingolipid - enriched membrane nanodomains, are involved into many aspects of the virus life cycle. Our previous study found that lipid rafts integrity was essential for CA16 replication, but how lipid rafts regulate CA16 replication through activating downstream signaling remains largely unknown. Thus, in this study, we revealed that lipid rafts were required for activation of PI3K/Akt signaling at early stage of CA16 infection. Treatment with wortmannin significantly reduced the expression of virus protein, indicating PI3K/Akt signaling was beneficial for early stage of virus infection. In addition, lipid rafts integrity was also indispensable for PI3K/Akt activation during the late stage of CA16 infection, which played critical functions in mediating sterol regulatory element-binding proteins 1 (SREBP1) maturation. Whereas, over-expression of SREBP1 exhibited inhibition on virus replication, suggesting that PI3K/Akt signaling and SREBP1 might positively and negatively influence virus replication in two different stages of infection, respectively. Taken together, our study demonstrates an important role of the lipid raft-associated PI3K/Akt/SREBP1 signaling in modulating CA16 replication, which will deepen our understanding mechanism of CA16 infection.
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http://dx.doi.org/10.1016/j.vetmic.2020.108921DOI Listing
January 2021

Variations in physicochemical properties of airborne particles during a heavy haze-to-dust episode in Beijing.

Sci Total Environ 2021 Mar 17;762:143081. Epub 2020 Oct 17.

State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China; Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Nanjing University of Information Science & Technology, Nanjing 210044, China. Electronic address:

The variations in physicochemical properties of airborne particles collected during a typical transition from haze to dust were investigated using single particle analysis with transmission and scanning electron microscopes combined with online measurement of chemical compositions of airborne particles in Beijing in February 2013. The transition was divided into three phases based on the weather condition. During haze pollution (Phase 1), gaseous and particle pollutants enhanced gradually. Results from single particle analysis showed that more coatings and more anthropogenic elements (e.g., S) appeared on the surface of fine and coarse particles, which was probably caused by efficient aqueous-phase reactions under high humidity (70%) condition. Phase 2 was dust intrusion episode. PM reached over 1000 μg m. Larger fractions of mineral particles and bare-like soot particles were observed in fine particles, while the fraction of secondary particles with coatings decreased. The proportion of black carbon in submicron particles also increased. Photochemical oxidation in gas phase likely dominated in secondary formation under high O concentration. After the dust episode (Phase 3), secondary formation enhanced obviously. Soot aged quickly and had a larger mode of 0.45 μm than the other phases. The size modes of airborne fine particles during Phases 1 and 3 were 0.35 μm, which were a bit larger than that during Phase 2 (0.24 μm). These results indicate that dust plumes accompanied with strong wind brought mineral particles in both fine and coarse modes and freshly emitted particles with smaller sizes, and swept away pre-presence air pollutants. This study could provide detailed information on the physicochemical properties of airborne particles during typical severe pollution processes in a short time. Such short-term change should be taken into account in order to more accurately assess the environmental, climatic and health-related effects of airborne particles.
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http://dx.doi.org/10.1016/j.scitotenv.2020.143081DOI Listing
March 2021

Hydroxyl, hydroperoxyl free radicals determination methods in atmosphere and troposphere.

J Environ Sci (China) 2021 Jan 27;99:324-335. Epub 2020 Jul 27.

State Key Joint Laboratory of Environment Simulation and Pollution Control (Peking University), College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China. Electronic address:

The hydroxyl radical (•OH) has a crucial function in the oxidation and removal of many atmospheric compounds that are harmful to health. Nevertheless, high reactivity, low atmospheric abundance, determination of hydroxyl, and hydroperoxyl radical's quantity is very difficult. In the atmosphere and troposphere, hydroperoxyl radicals (HO) are closely demanded in the chemical oxidation of the troposphere. But advances in technology have allowed researchers to improve the determination methods on the research of free radicals through some spectroscopic techniques. So far, several methods such as laser-induced fluorescence (LIF), high-performance liquid chromatography (HPLC), and chemical ionization mass spectroscopy have been identified and mostly used in determining the quantity of hydroxyl and hydroperoxyl radicals. In this systematic review, we have advised the use of scavenger as an advance for further researchers to circumvent some of these problems caused by free radicals. The primary goal of this review is to deepen our understanding of the functions of the most critical free radical (•OH, HO) and also understand the currently used methods to quantify them in the atmosphere and troposphere.
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http://dx.doi.org/10.1016/j.jes.2020.06.038DOI Listing
January 2021

Why multilingual, and how to keep it-An evolutionary dynamics perspective.

Authors:
Zhijun Wu

PLoS One 2020 10;15(11):e0241980. Epub 2020 Nov 10.

Department of Mathematics, Iowa State University, Ames, Iowa, United States of America.

While many languages are in danger of extinction worldwide, multilingualism is being adopted for communication among different language groups, and is playing a unique role in preserving language and cultural diversities. How multilingualism is developed and maintained therefore becomes an important interdisciplinary research subject for understanding complex social changes of modern-day societies. In this paper, a mixed population of multilingual speakers and bilingual speakers in particular is considered, with multilingual defined broadly as zero, limited, or full uses of multiple languages or dialects, and an evolutionary dynamic model for its development and evolution is proposed. The model consists of two different parts, formulated as two different evolutionary games, respectively. The first part accounts for the selection of languages based on the competition for population and social or economic preferences. The second part relates to circumstances when the selection of languages is altered, for better or worse, by forces other than competition such as public policies, education, or family influences. By combining competition with intervention, the paper shows how multilingualism may evolve under these two different sources of influences. It shows in particular that by choosing appropriate interventional strategies, the stable co-existence of languages, especially in multilingual forms, is possible, and extinction can be prevented. This is in contrast with major predictions from previous studies that the co-existence of languages is unstable in general, and one language will eventually dominate while all others will become extinct.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0241980PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7654808PMC
December 2020

The accessory protein ORF3 of porcine epidemic diarrhea virus inhibits cellular interleukin-6 and interleukin-8 productions by blocking the nuclear factor-κB p65 activation.

Vet Microbiol 2020 Dec 16;251:108892. Epub 2020 Oct 16.

College of Animal Science and Veterinary Medicine, HeiLongJiang BaYi Agricultural University, Daqing 163319, China; College of Life Science and Technology, HeiLongJiang BaYi Agricultural University, Daqing 163319, China; Biotechnology Center, HeiLongJiang BaYi Agricultural University, Daqing 163319, China. Electronic address:

Porcine epidemic diarrhea virus (PEDV) is an enveloped, single-stranded positive-sense RNA virus that belongs to a porcine entero-pathogenic alphacoronavirus, causing lethal watery diarrhea in piglets. Despite existing study reports the sole accessory protein ORF3 identified as NF-κB antagonist, the contribution of PEDV ORF3 to production of the pro-inflammatory cytokines mediated by NF-κB signaling remains largely unknown. Thus in this present study, we showed that PEDV ORF3 protein significantly inhibited the productions of pro-inflammatory cytokines interleukin-6 (IL-6) and IL-8. The phosphorylation of IκBα was inhibited by ORF3 protein, but no degradation of IκBα was induced in ORF3-expressing cells. Furthermore, PEDV ORF3 inhibited NF-κB activation through preventing nuclear factor p65 phosphorylation and down-regulating p65 expression level, as well as interfering nuclear translocation of p65, eventually resulting into the inhibition of IL-6 and IL-8 production. Our study definitely links PEDV ORF3 to inhibition of pro-inflammatory cytokines production, which will provide new insight into the molecular mechanisms of NF-κB activity inhibited by PEDV proteins to facilitate virus evasion of host innate immune.
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http://dx.doi.org/10.1016/j.vetmic.2020.108892DOI Listing
December 2020

The anti-lipidemic role of soluble dietary fiber extract from okara after fermentation and dynamic high-pressure microfluidization treatment to Kunming mice.

J Food Sci Technol 2020 Nov 28;57(11):4247-4256. Epub 2020 Apr 28.

School of Food Science, Sichuan Agricultural University, Ya'an, 625014 China.

The present study was conducted to evaluate the anti-hyperlipidemia ability of the dietary fiber extracted from okara in mice fed a high cholesterol diet. The dietary fiber was extracted from okara by combining fermentation with dynamic high-pressure microfluidization. An animal model was established to test the hypothesis that soluble dietary fiber, insoluble dietary fiber and total dietary fiber inhibit the fatty liver could be related to the total lipids and cholesterol including total cholesterol, triglyceride, low-density lipoprotein cholesterol and high-density lipoprotein cholesterol in the serum. Compared with mice fed with simvastatin, mice fed dietary fiber can significantly reduce their serum total cholesterol, low-density lipoprotein cholesterol, triglyceride, and atherogenic index whereas no significant effect on high-density lipoprotein cholesterol was observed. Dietary fiber lowered a high level of liver total cholesterol and triglyceride. The dietary fiber extracted from okara might play an important role in the prevention of hyperlipidemia in high cholesterol mice and could be used as a natural supplement to a high cholesterol diet of functional food, due to the suppression of liver lipid synthesis.
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http://dx.doi.org/10.1007/s13197-020-04463-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7520489PMC
November 2020

Investigation of the structural, physical properties, antioxidant, and antimicrobial activity of chitosan- nano-silicon aerogel composite edible films incorporated with okara powder.

Carbohydr Polym 2020 Dec 15;250:116842. Epub 2020 Aug 15.

Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA, 01003, USA.

The chitosan/okra powder/nano-silicon aerogel composite films were prepared by casting method and their physicochemical properties and structural characterization were studied. The results showed that the composite film had good mechanical properties, barrier properties and optical properties. The composite film has strong flexibility. The surface glossiness of C/D/S film was 14.4Gu. As for the antibacterial activity, all the composite films had strong antibacterial activity against Gram-negative (E. coli) and Gram-positive (S. aureus), and the inhibition zone of C/D/S against E. coli reached 551.96 mm, the inhibition zone for S. aureus was 350.29 mm. The composite film had uniform, non-porous, continuous and dense surface characteristics. The structural characterization confirmed that there was good compatibility between chitosan, okara powder and nano-silicon aerogel. In summary, the composite films had excellent performance and structure, which promoted the research of functional packaging films.
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http://dx.doi.org/10.1016/j.carbpol.2020.116842DOI Listing
December 2020

Study on physicochemical properties, antioxidant and antimicrobial activity of okara soluble dietary fiber/sodium carboxymethyl cellulose/thyme essential oil active edible composite films incorporated with pectin.

Int J Biol Macromol 2020 Dec 9;165(Pt A):1241-1249. Epub 2020 Oct 9.

College of Food Science, Sichuan Agricultural University, Ya'an 625014, China. Electronic address:

Active edible films based on okara soluble dietary fiber (SDF), pectin, sodium carboxymethyl cellulose (CMCNa) and thyme essential oil (TEO) were successfully prepared. We aimed to exploit biodegradable edible films and realize the full utilization of waste resources. The effects of different amounts of pectin on the properties and structural characterization of the composite film with or without TEO were studied using a solution casting evaporation method. In general, the addition of TEO can improve the properties of the composite membrane. Pectin was homogeneously distributed within the films and exhibited good interaction with the polymer matrix. The addition of pectin led to significantly higher mechanical and optical properties of the composite film, compared with SDF/CMC-Na composite film. The tensile strength reached 21.419 ± 2.22 MPa, and the minimum transparency reduced to 88.9% ± 0.42%, with increasing pectin. Notably, the water resistance and oil resistance were enhanced. The composite films also possessed satisfactory antioxidant activity, with a DPPH-free radical scavenging rate of 46.33% ± 0.72%, while antibacterial activity against E. coli and S. aureus bacteria was not obvious. Antioxidant and antibacterial SDF/pectin/CMC-Na composite films with enhanced mechanical, optical and barrier properties are excellent candidates for active edible packaging.
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http://dx.doi.org/10.1016/j.ijbiomac.2020.10.005DOI Listing
December 2020

Annual variations of black carbon over the Yangtze River Delta from 2015 to 2018.

J Environ Sci (China) 2020 Oct 26;96:72-84. Epub 2020 May 26.

Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, Nanjing University of Information Science &Technology, Nanjing 210044, China.

In this study, the black carbon (BC) measurements in the atmosphere of Nanjing, China were continuously conducted from 2015 to 2018 using a Model AE-33 aethalometer. By combining dataset of PM, PM, CO, NO, SO, O and meteorological parameters, the temporal variations and the source apportionment of BC were given in this study. The results showed that the PM mass concentrations decreased in Nanjing, with an average annual rate of variation of 6.50 μg/(m⋅year). Differently, the annual average concentrations of BC increased with an average annual variation rate of 214.71 ng/(m⋅year). The seasonal variations showed the pattern of BC mass concentrations in winter > autumn > spring > summer. The diurnal variations of BC mass concentrations showed a double-peak in all four seasons. The first peak occurred at approximately 7:00 in spring, summer and autumn and around 8:00 in winter. The second peak took place after 18:00. The average AAE (absorption Ångström exponent) was 1.26 with a maximum of 1.35 during wintertime and the lowest (1.12) during summertime. In addition, the AAE was smaller in the daytime than that at night, with a minimum occurring between 13:00 and 14:00. BC and visibility show a good power-function relationship at different humidity levels. The average values of the visibility thresholds of the BC mass concentrations in spring, summer, autumn and winter were 1.326, 5.522, 1.340 and 0.708 μg/m, respectively. The greater the relative humidity, the smaller the visibility threshold for the BC mass concentrations was.
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http://dx.doi.org/10.1016/j.jes.2020.04.019DOI Listing
October 2020

In situ continuous hourly observations of wintertime nitrate, sulfate and ammonium in a megacity in the North China plain from 2014 to 2019: Temporal variation, chemical formation and regional transport.

Chemosphere 2021 Jan 25;262:127745. Epub 2020 Jul 25.

State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100083, China; University of Chinese Academy of Sciences, Beijing, 100049, China. Electronic address:

Nitrate (NO), sulfate (SO) and ammonium (NH) in airborne fine particles (PM) play a vital role in the formation of heavy air pollution in northern China. In particular, the increasing contribution of NO to PM has attracted worldwide attention. In this study, a highly time-resolved analyzer was used to measure water-soluble inorganic ions in PM in one of the fastest-developing megacities, Tianjin, China, from November 15 to March 15 (wintertime heating period) in 2014-2019. Severe PM pollution episodes markedly decreased during the heating period from 2014 to 2019. The highest concentrations of NO and SO were recorded in the heating period of 2015/2016. Afterwards, NO decreased from 2015/2016 (20.2 ± 23.8 μg/m) to 2017/2018 (11.6 ± 14.8 μg/m) but increased with increasing NO concentrations during the heating period of 2018/2019. A continuous decrease in the SO concentration led to a decrease in SO from 2015/2016 (16.8 ± 21.8 μg/m) to 2018/2019 (6.5 ± 8.9 μg/m). The NO and SO concentrations increased as the air quality deteriorated. However, the proportion of NO and SO in PM slightly increased when the air quality deteriorated from moderate pollution (MP) to severe pollution (SP) levels. The average molar ratios of NH to [NO+2 × (SO)] were 1.7, 0.9, 1.2, 1.2 and 1.5 for the heating periods of 2014/2015, 2015/2016, 2016/2017, 2017/2018 and 2018/2019, respectively, most of which were higher than 1.0, thus revealing an overall excess of NH during the heating periods. However, the molar equivalent ratios of [NH] to [NO+2 × (SO)] were less than 1 under increasing PM pollution. The molar equivalent ratios of [NO]/[SO] were positively correlated with those of [NH]/[SO]. When the molar equivalent ratios of [NH]/[SO] were more than 1.5, those of [NO]/[SO] increased from close to 1 to higher values, indicating that the dominance of NO formation played an important role. The results of nonparametric wind regression exhibited distinct hot spots of NO, SO and NH (higher concentrations) in the wind sectors between NE and SE at wind speeds of approximately 6-21 km/h. The southern areas in the North China Plain and parts of the western areas of China contributed more NO, SO and NH than other areas to the study site. The abovementioned areas were also characterized by a higher contribution of NO than of SO to the study site and by NH-rich conditions. In summary, more efforts should be made to reduce NO in the Beijing-Tianjin-Hebei region. This study provides observational evidence of the increasingly important role of nitrate as well as scientific support for formulating effective control strategies for regional haze in China.
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http://dx.doi.org/10.1016/j.chemosphere.2020.127745DOI Listing
January 2021

Effect of dietary arginine-to-lysine ratio in lactation on biochemical indices and performance of lactating sows.

J Anim Sci 2020 Sep;98(9)

Institute of Animal Science, Guangdong Academy of Agricultural Sciences, State Key Laboratory of Livestock and Poultry Breeding, Key Laboratory of Animal Nutrition and Feed Science in South China, Ministry of Agriculture and Rural Affairs, Guangdong Key Laboratory of Animal Breeding and Nutrition, Guangzhou, China.

The present study investigated the effect of optimizing the total dietary arginine (Arg)-to-lysine (Lys) ratios on the metabolism of lactating sows and piglet performance by supplementation with l- Arg during lactation. A total of 200 multiparous sows (three to six parities, Yorkshire × Landrace) were selected and randomly and equally assigned to five groups in lactation, and finally, 36, 34, 35, 36, and 33 dams completed the study in the dietary treatments, respectively, where the diets consisted of five step-up Arg-to-Lys ratios (0.9, 1.0, 1.1, 1.2, and 1.3) by the addition of 0%, 0.10%, 0.20%, 0.30%, and 0.40% Arg. The diets contained 3.37 to 3.38 Mcal of digestible energy/kg energy, 17.73% to 17.75% crude protein, and 0.98% to 1.01% Lys and were fed ad libitum during lactation. The performance of sows and suckling piglets was measured, and plasma and milk samples were collected for analysis. The feed intake of sows as well as litter weight gain during lactation increased linearly (P ≤ 0.05), while maternal backfat and milk composition were not affected (P > 0.05) as the dietary Arg-to-Lys ratios increased. Analyzed plasma biochemical indices, including concentrations of free Arg, Orn, and Glu, and prolactin, insulin, and follicle-stimulating hormone, responded linearly (P ≤ 0.05) to increases in dietary Arg-to-Lys ratios. The dietary Arg-to-Lys ratios of 1.01 and 1.02 were optimal for maternal feed intake and litter weight gain, based on broken-line models. Collectively, the results of this study indicate that increasing total dietary Arg-to-Lys ratios in lactation was beneficial for the performance of lactating sows and suckling piglets, and dietary Arg-to-Lys ratios of 1.01 and 1.02 were optimal, from regression analyses, for the practical feeding of lactating sows.
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http://dx.doi.org/10.1093/jas/skaa261DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7511058PMC
September 2020

Photoprotective effect of Astragalus membranaceus polysaccharide on UVA-induced damage in HaCaT cells.

PLoS One 2020 21;15(7):e0235515. Epub 2020 Jul 21.

Key Laboratory of Marine Drugs, Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao, China.

Background: The skin provides a predominant barrier against chemical, physical and microbial incursion. The intemperate exposure to ultraviolet A (UVA) radiation can cause excessive cellular oxidative stress, leading to skin damage, proteins damage and mitochondrial dysfunction. There is sufficient evidences supporting the proposal that mitochondria is highly implicated in skin photo-damage.

Methods: In the present study, a polysaccharide isolated from Astragalus membranaceus was further purified to be an α-glucan, which was further investigated its beneficial influence on UVA-induced photo-damage in HaCaT cells.

Results: Our results showed that the purified Astragalus membranaceus polysaccharide (AP) can protect HaCaT cells from UVA-induced photo-damage through reducing UVA-induced intracellular ROS production and mitochondrial membrane potential, thereby altering ATP content. It was found that the UVA induced damage in HaCaT cells could be effectively restored by co-treatment with AP.

Conclusions: AP exhibited promising potential for advanced application as multifunctional skin care products and drugs.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0235515PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7373302PMC
September 2020

An amplitude prediction model for a giant magnetostrictive ultrasonic transducer.

Ultrasonics 2020 Dec 6;108:106017. Epub 2019 Sep 6.

Beijing Key Lab of Precision/Ultra-precision Manufacturing Equipments and Control, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China.

Rotary ultrasonic machining (RUM) is widely used in the processing of brittle and hard materials. The application of giant magnetostrictive ultrasonic transducers (GMUT) with effective vibration performance is an increasingly popular field of research within RUM. A generalized amplitude prediction model for GMUT is obtained in this paper by first providing an equivalent kinetics model of the GMUT. Considering the influence on interaction force between Terfenol-D and the external mechanical mechanism, the prestress mechanism of Terfenol-D and the joint face of the horn are determined as equivalent to two spring-damping systems in series, and a general GMUT vibration equation is established. The equivalent stiffness of the prestress mechanism is then identified, and the mechanical quality factor of the vibration system is calculated by impedance analysis. The influence of the joint face of the horn and the prestress mechanism on the amplitude is then studied by nonlinear least square fitting. Based on a magnetostriction and magnetization model, an odd power amplitude prediction model with mechanical quality factor, excitation current amplitude, and excitation frequency is proposed. The experimental results demonstrate that the proposed model can effectively predict the output amplitude of the GMUT with different mechanical quality factors for different excitation signals, providing a method for system design and optimization of the GMUT.
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http://dx.doi.org/10.1016/j.ultras.2019.106017DOI Listing
December 2020

Seasonal variation characteristics of hydroxyl radical pollution and its potential formation mechanism during the daytime in Lanzhou.

J Environ Sci (China) 2020 Sep 16;95:58-64. Epub 2020 Apr 16.

Gansu Food Inspection and Research Institute, Lanzhou 730030, China.

Hydroxyl free radicals (OH radicals) play the main role in atmospheric chemistry and their involving reactions are the dominant rate determining step in the formation of secondary fine particulate matter and in the removal of air pollutants from the atmosphere. In this paper, we studied the seasonal variation characteristics of OH radicals during the daytime in Lanzhou and explored the potential formation mechanism of high concentration OH radicals. We found that the OH radicals in four seasons was 2.7 × 10, 2.6 × 10, 3.1 × 10, and 2.2 × 10 cm, respectively. Since the rainfall was concentrated in summer, the wet deposition had a significant effect on removing OH radicals. Among the four pollutants (including ozone (O), volatile organic compounds (VOCs), nitrogen dioxide (NO) and fine particulate matter (PM)), the variation of OH radicals were closely related to ozone concentration especially in spring and summer. In autumn, the correlation between PM and OH radicals were the closest among the observing pollutants and its formation mechanism was different conventional regeneration pathway. In Event 1, high concentration of ozone was the main source of OH radicals; under the high humidity condition, except for ozone, the multiple factors including VOCs, NO and PM interplayed and leaded to the Event 2.
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http://dx.doi.org/10.1016/j.jes.2020.03.045DOI Listing
September 2020