A New Type of Quartz Smog Chamber : Design and Characterization

Publisher Copyright: ©Since the 1960s, many indoor and outdoor smog chambers have been developed worldwide. However, most of them are made of Teflon films, which have relatively high background contaminations due to the wall effect. We developed the world's first medium-size quartz chamber (10 m(3)), which is jointed with 32 pieces of 5 mm thick polished quartz glasses and a stainless-steel frame. Characterizations show that this chamber exhibits excellent performance in terms of relative humidity (RH) (2-80%) and temperature (15-30 +/- 1 degrees C) control, mixing efficiency of the reactants (6-8 min), light transmittance (>90% above 290 nm), and wall loss of pollutants. The wall loss rates of the gas-phase pollutants are on the order of 10(-4) min(-1) at 298 K under dry conditions. It is 0.08 h(-1) for 100-500 nm particles, significantly lower than those of Teflon chambers. The photolysis rate of NO2 (J(NO2)) is automatically adjustable to simulate the diurnal variation of solar irradiation from 0 to 0.40 min(-1). The inner surface of the chamber can be repeatedly washed with deionized water, resulting in low background contaminations. Both experiments (toluene-NOx and alpha-pinene-ozone systems) and box model demonstrate that this new quartz chamber can provide high-quality data for investigating SOA and O-3 formation in the atmosphere.Peer reviewe

Targeting histone deacetylase 3 (HDAC3) in the bone marrow microenvironment inhibits multiple myeloma proliferation by modulating exosomes and IL-6 trans-signaling

Multiple myeloma (MM) is an incurable cancer that derives pro-survival/proliferative signals from the bone marrow (BM) niche. Novel agents targeting not only cancer cells, but also the BM-niche have shown the greatest activity in MM. Histone deacetylases (HDACs) are therapeutic targets in MM and we previously showed that HDAC3 inhibition decreases MM proliferation both alone and in co-culture with bone marrow stromal cells (BMSC). In this study, we investigate the effects of HDAC3 targeting in BMSCs. Using both BMSC lines as well as patient-derived BMSCs, we show that HDAC3 expression in BMSCs can be induced by co-culture with MM cells. Knock-out (KO), knock-down (KD), and pharmacologic inhibition of HDAC3 in BMSCs results in decreased MM cell proliferation; including in autologous cultures of patient MM cells with BMSCs. We identified both quantitative and qualitative changes in exosomes and exosomal miRNA, as well as inhibition of IL-6 trans-signaling, as molecular mechanisms mediating anti-MM activity. Furthermore, we show that HDAC3-KD in BM endothelial cells decreases neoangiogenesis, consistent with a broad effect of HDAC3 targeting in the BM-niche. Our results therefore support the clinical development of HDAC3 inhibitors based not only on their direct anti-MM effects, but also their modulation of the BM microenvironment

Asymptotic Synchronization of Fractional-Order Complex Dynamical Networks with Different Structures and Parameter Uncertainties

This paper deals with the asymptotic synchronization of fractional-order complex dynamical networks with different structures and parameter uncertainties (FCDNDP). Firstly, the FCDNDP model is proposed by the Riemann–Liouville (R-L) fractional derivative. According to the property of fractional calculus and the Lyapunov direct method, an original controller is proposed to achieve the asymptotic synchronization of FCDNDP. Our controller is more adaptable and effective than those in other literature. Secondly, a sufficient condition is given for the asymptotic synchronization of FCDNDP based on the asymptotic stability theorem and the matrix inequality technique. Finally, the numerical simulations verify the effectiveness of the proposed method

Versatile Medium Entropy Ti-Based Bulk Metallic Glass Composites

An ultra-strong Ti-based bulk metallic glass composite was developed via the transformation-induced plasticity (TRIP) effect to enhance both the ductility and work-hardening capability of the amorphous matrix. The functionally graded composites with a continuous gradient microstructure were obtained. It was found that the austenitic center possesses good plasticity and toughness. Furthermore, the amorphous surface exhibited high strength and hardness, as well as excellent wear corrosion resistance. Compared with the Ti-6Al-4V alloy, bulk metallic glass composites (BMGCs) exhibit better spontaneous passivation behavior during the potential dynamic polarization. No crystallization was observed on the friction surface, indicating their good friction-reduction and anti-wear properties

Review of fractional epidemic models

The global impact of corona virus (COVID-19) has been profound, and the public health threat it represents is the most serious seen in a respiratory virus since the 1918 influenza A(H1N1) pandemic. In this paper, we have focused on reviewing the results of epidemiological modelling especially the fractional epidemic model and summarized different types of fractional epidemic models including fractional Susceptible-Infective-Recovered (SIR), Susceptible-Exposed-Infective-Recovered (SEIR), Susceptible-Exposed-Infective-Asymptomatic-Recovered (SEIAR) models and so on. Furthermore, we propose a general fractional SEIAR model in the case of single-term and multi-term fractional differential equations. A feasible and reliable parameter estimation method based on modified hybrid Nelder-Mead simplex search and particle swarm optimisation is also presented to fit the real data using fractional SEIAR model. The effective methods to solve the fractional epidemic models we introduced construct a simple and effective analytical technique that can be easily extended and applied to other fractional models, and can help guide the concerned bodies in preventing or controlling, even predicting the infectious disease outbreaks.</p

High temperature oxidation behavior of 310S heat-resistant steel

The oxidation kinetics and film structure of two kinds of 310S heat-resistant steels (1# and 2#) with different grain sizes and composition at 800-1100 ℃ were studied by static oxidation discontinuous mass gain method. The differences of oxidation properties between the two steels were compared, and the growth mechanism of oxide film and the reasons for the differences were clarified. The results show that the oxide film is composed of Si-rich oxide layer and Cr-rich oxide layer and the oxidation rate of sample 1# is lower at 800-900 ℃; Cr-Mn oxide layer is added to the oxide film at 1000 ℃ and is transformed into Cr-Mn-Fe oxide layer at 1100 ℃, and their oxidation rates are similar; on the whole, the oxide film of sample 2# is denser, smoother, more adherent and more protective at all temperatures. Particularly, the spinel layer and the chromium oxide layer of the two are greatly different in the form at 1100 ℃, and the form of the oxide film of sample 2# is more conducive to long-term oxidation resistance. In general, the oxidation resistance of sample 2# is better than that of sample 1#. The smaller average grain size and more uniform grain of sample 2# improve the diffusion flux of preferred oxidation elements and reduce the uneven growth of oxide film, resulting in the differences of oxidation properties between the two

Changes in Soil Bacterial Community Structure in Bermudagrass Turf under Short-Term Traffic Stress

Bermudagrass (Cynodon dactylon (L.) Pers.) is an extensively utilized turf grass for football fields and golf courses. Traffic stress is one of the most important stresses affecting the life of turf, which leads to a decrease in turf quality and changes in the soil microbial community structure. The structural change in soil bacterial community is an important reference for turf growth, maintenance, and restoration. Tifgreen bermudagrass turf and Common bermudagrass turf were applied with traffic treatment by a traffic simulator with moderate intensity to explore soil bacterial community structural changes in turf under traffic stress. The environmental factors including turf quality indicators and soil properties were measured, and the association of the soil bacterial community diversity with the environment factors was analyzed. As a result, traffic treatments significantly changed the soil properties and bacterial community composition in two bermudagrass species at the phylum and genus level. Actinobacteria, Chloroflexi, and Verrucomicrobia showed significantly high abundance in turf soils under traffic stress. The soil bacterial ACE, Chaol, and Shannon indexes of two bermudagrass species under traffic stress were significantly lower than non-traffic stress. The bacterial community structure was highly correlated with some turf quality indicators and soil properties under traffic stress. Our results illustrate that compared to Common bermudagrass, Tifgreen bermudagrass had better turf quality under traffic stress and less changes in its bacterial community structure, perhaps Tifgreen bermudagrass is a better choice of grass for sports turf as opposed to Common bermudagrass

Effects of Nitrogen Content and Strain Rate on the Tensile Behavior of High-Nitrogen and Nickel-Free Austenitic Stainless Steel

The uniaxial tensile behaviors of Fe-19Cr-16Mn-2Mo-0.49N and Fe-18Cr-16Mn-2Mo-0.85N high-nitrogen and nickel-free austenitic stainless steels at two strain rates of 10−2 s−1 and 10−4 s−1 were comparatively investigated. The related deformation microstructure was characterized and fracture mechanism was analyzed. The results show that the nitrogen content and strain rate both have significant effects on the tensile properties of the tested steels. As the strain rate is the same, the tested steel containing a higher nitrogen content has higher Rm and Rp0.2. However, Rm is higher at a lower strain rate and Rp0.2 is higher at a higher strain rate in the case of the same nitrogen content. The tested steel with a lower nitrogen content (0.49 wt.%N) tensioned at a lower strain rate of 10−4 s−1 obtains the highest elongation, while the tested steel with a higher nitrogen content (0.85 wt.%N) tensioned at a higher strain rate of 10−2 s−1 has the lowest elongation. The tensile plastic deformation is mainly governed by slip and twinning, affected jointly by stacking fault energy and short-range order. Dislocation slip featured by planar slip bands and twin-like bands is the main deformation structure in the tested steel containing a higher nitrogen content (0.85 wt.%N) tensioned at a lower strain rate of 10−4 s−1, whereas twinning deformation becomes more prominent with decreasing nitrogen content and increasing strain rate