Ibuprofen (IBU), a widely used antipyretic and analgesic, has been frequently detected in various natural water systems. Advanced oxidation processes (AOPs) are effective ways to remove pollutants ...from water. The degradation of IBU under UV/H
2
O
2
conditions in the presence of various kinds of natural dissolved matter was investigated using density functional theory (DFT). The eco-toxicological properties were predicted based on a quantitative structure-activity relationship (QSAR) model. The calculated results showed that two H-abstraction reactions occurring at the side chain are predominant pathways in the initial reaction. H
2
O, NH
3
, CH
3
OH, C
2
H
5
OH, HCOOH and CH
3
COOH can catalyze the H transfer in the degradation process through decreasing the energy barriers and the catalysis effects follow the order of NH
3
> alcohols > acids > H
2
O. The catalysis effects differ under acid or alkaline conditions. The overall rate coefficient of the reaction of IBU with &z.rad;OH is calculated to be 5.04 × 10
9
M
−1
s
−1
at 298 K. IBU has harmful effects on aquatic organisms and human beings and the degradation process cannot significantly reduce its toxicity. Among all products, 2-(4-formylphenyl)propanoic acid, which is more toxic than IBU, is the most toxic with acute and chronic toxicity, developmental toxicity, mutagenicity, genotoxic carcinogenicity and irritation/corrosivity to skin. The findings in this work provide new insights into the degradation of IBU and can help to assess its environmental risks.
Natural dissolved matter can significantly catalyze the degradation of ibuprofen during the UV/H
2
O
2
process forming more toxic products.
Ibuprofen (IBU), a widely used antipyretic and analgesic, has been frequently detected in various natural water systems. Advanced oxidation processes (AOPs) are effective ways to remove pollutants ...from water. The degradation of IBU under UV/H
O
conditions in the presence of various kinds of natural dissolved matter was investigated using density functional theory (DFT). The eco-toxicological properties were predicted based on a quantitative structure-activity relationship (QSAR) model. The calculated results showed that two H-abstraction reactions occurring at the side chain are predominant pathways in the initial reaction. H
O, NH
, CH
OH, C
H
OH, HCOOH and CH
COOH can catalyze the H transfer in the degradation process through decreasing the energy barriers and the catalysis effects follow the order of NH
> alcohols > acids > H
O. The catalysis effects differ under acid or alkaline conditions. The overall rate coefficient of the reaction of IBU with ˙OH is calculated to be 5.04 × 10
M
s
at 298 K. IBU has harmful effects on aquatic organisms and human beings and the degradation process cannot significantly reduce its toxicity. Among all products, 2-(4-formylphenyl)propanoic acid, which is more toxic than IBU, is the most toxic with acute and chronic toxicity, developmental toxicity, mutagenicity, genotoxic carcinogenicity and irritation/corrosivity to skin. The findings in this work provide new insights into the degradation of IBU and can help to assess its environmental risks.
CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1), a well-known E3 ubiquitin ligase, functions as a central regulator of plant growth and photomorphogenic development in plants, including hypocotyl elongation. ...It has been well-established that, in darkness, COP1 targets many photomorphogenesis-promoting factors for ubiquitination and degradation in the nucleus. However, increasing evidence has shown that a proportion of COP1 is also localized outside the nucleus in dark-grown seedlings, but the physiological function of this localization remains largely unclear. In this study, we demonstrate that COP1 directly targets and mediates the degradation of WAVE-DAMPENED 2-LIKE 3 (WDL3) protein, a member of the microtubule-associated protein (MAP) WVD2/WDL family involved in regulating hypocotyl cell elongation of Arabidopsis seedlings. We show that COP1 interacts with WDL3 in vivo in a dark-dependent manner at cortical microtubules. Moreover, our data indicate that COP1 directly ubiquitinates WDL3 in vitro and that WDL3 protein is degraded in WT seedlings but is abundant in the cop1 mutant in the dark. Consistently, introduction of the wdl3 mutation weakened, whereas overexpression of WDL3 enhanced, the short-hypocotyl phenotype of cop1 mutant in darkness. Together, this study reveals a function of COP1 in regulating the protein turnover of a cytosol-localized MAP in etiolated hypocotyls, thus providing insights into COP1-mediated degradation of downstream factors to control seedling photomorphogenesis.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
2,4-dichlorophenoxyacetic (2,4-D) acid and 4-chlorophenoxyacetic acid (4-CPA), as widely utilized organochlorine pesticides, are normally detected in wastewater and atmosphere. Their harmfulness to ...the ecosystem cannot be ignored. UV/H2O2 is one of the most conventional advanced oxidation processes, which has remarkable advantages for the removal of refractory organic pollutants in wastewater. However, the reaction mechanisms and pathways of pollutants with reactive radicals are still unclear. In this study, the degradation efficacy and mechanisms during the photodegradation of 2,4-D and 4-CPA in UV/H2O2 processes were investigated by experiments and density functional theory calculations. The results showed that 2,4-D was more likely to be degraded by UV/H2O2 treatment than UV photolysis alone. In contrast, 4-CPA can be degraded effectively and rapidly under UV irradiation alone. By LC-MS analysis, the degradation products of 2,4-D and 4-CPA in the UV/H2O2 processes were identified and they were produced by hydroxylation and photolysis. Therefore, we speculated a competition mechanism presented between direct photolysis and indirect photolysis in the UV/H2O2 degradation of 2,4-D and 4-CPA. The OH-initiated reaction mechanisms of 2,4-D and 4-CPA in aqueous environments were investigated using quantum chemical methods SMD/M06–2X/6–311++G (3df, 2p)//SMD/M06–2X/6-311 + G (d,p). The pH dependence of the reaction mechanisms and rate constants in their degradation process induced by ·OH was also investigated. The calculation results showed that the ionic forms (2,4-D- and 4-CPA-) were more prone to react with ·OH in comparison to the corresponding molecular forms (2,4-D and 4-CPA). The total rate constants of 2,4-D and 4-CPA with OH increased with the pH from 1 to 10, and decreased with continued pH increase. The toxicities of 2,4-D, 4-CPA and their products were assessed by the QSAR-based toxicity evaluation software. The results showed that several products were more toxic than their parent compounds, such as 2,4-dichlorophenol, 3,5-dichlorocatechol, 4-chlorophenol and hydroquinone. This work can contribute to clarifying the environmental risks of 2,4-D and 4-CPA and offer a complete understanding for the photodegradation behavior of 2,4-D and 4-CPA in aqueous ecosystems.
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•Direct photolysis and ·OH-initiated oxidation of 2,4-D and 4-CPA were studied with DFT.•Effects of pH on degradation of 2,4-D and 4-CPA were investigated.•The rate constants of 2,4-D and 4-CPA with ·OH increase with increasing pH.•Toxicity of degradation products increased in comparison to 2,4-D and 4-CPA.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract
Composite shear wall (CSW) system consists of a steel boundary frame and a steel panel with a reinforced concrete (RC) panel attached to it using threaded bolts. Finite element (FE) ...simulations were conducted on two types of the CSW system, namely traditional and innovative CSW system, respectively. For traditional CSW system, the RC panel is in direct contact with the steel boundary frame; while for innovative CSW system, there is a gap in between. FE models were developed and validated using test data. The effects of major parameters, including steel panel thickness, RC panel thickness, and gap between frame and RC panel, were examined using the validated models. The numerical simulations indicated that steel panel thickness significantly affected lateral strength and initial stiffness of both innovative and traditional CSW systems. Although RC panel thickness and gap between frame and RC panel had negligible effects on system strength and stiffness characteristics, they should also be carefully designed to ensure local stability of the steel panel and system ductility.
An extensive first-principles database of alloying behavior of 37 elements in the Al(111)/TiB2(0001) interface is presented. The interfacial ability is systematically compared via the formation ...energy, interface energy, and work of adhesion. The thermodynamically most stable interface with the Ti terminal and center stacking sequence is selected to analyze the alloying behavior. According to the interfacial stability and wettability, an alloying trend map containing 11 excellent elements (Mg, Ca, Ag, Ce, Au, Pd, Y, Sc, Pt, Hf, and Zr) is obtained. These elements can effectively improve the dispersion of TiB2 particles in Al-based composites by promoting the formation of the Al/TiB2 interface and improving the interfacial wettability. Based on the number of valence electrons in the d orbital, these alloying elements can be divided into zero-d (Mg and Ca), low-d (Sc, Y, Zr, Ce, and Hf), and high-d (Pd, Ag, Pt, and Au) elements. In combination with the electronic structure of the alloying interfaces, the alloying mechanisms are discussed depending on the hybridization between Al and alloying atoms. Generally, our calculation guides the interface alloying strategy to enhance the particle dispersion in the metal matrix composite and provides a fundamental explanation for the related interfacial mechanisms.
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IJS, KILJ, NUK, PNG, UL, UM
•Graphene quantum dots (GQDs) were added to graphene-oxide–based memristive devices.•Introduction of GQDs improved the resistive switching and magnetic modulation.•State transition from sp2 to sp3 ...aided by GQDs help induce resistive switching.•GQDs also provide magnetic linkage between domains enabling magnetic modulation.
Graphene materials have attracted considerable research interest owing to their applications in memristor and prospective spintronic devices. In this work, the bifunctional resistive and magnetic switching effect is investigated in Ag/graphene quantum dots (GQDs): graphene oxide (GO)/ITO device: (1) In the low-resistance state, the conductive filaments are formed by oxygen migration away inducing the C–C sp2 groups. (2) In the high-resistance state, the directions of magnetic moment align by increasing the C–O sp3 group. The resistive switching ratios and saturation magnetization of GQDs memristor are shown to be approximately 20 and 2.2 times higher than that of GQDs-free memristor, respectively. Tunable magnetic switching makes GO-based memristive devices boosted by GQDs a promising candidate to future voltage-controlled, low-power, and high-density spintronics devices.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The Li-rich Mn-based material, with high energy density, less toxicity and low cost, is regarded as one of the potential cathode candidates for the next generation lithium-ion batteries (LIBs). ...However, some issues need to be addressed before large-scale commercialized application, such as capacity attenuation, low initial coulomb efficiency and poor rate performance, caused by the structure defects and oxygen escape from the crystal lattice at high voltage. Here, the Na+ and Mo6+ dopants are introduced to Li1.2Mn0.54Ni0.13Co0.13O2 by sol-gel method, with slight Li+ displaced by Na+ and tiny Mo6+ substituting transition metal ions, respectively. The doping effects on the Li layer spacing, Li/Ni mixing and oxygen vacancy defects have been examined. Regarding the doped samples, the valence states of transition metal elements and electrochemical performance are systematically studied. The Na+ and Mo6+ co-doping not only expands the lithium layer spacing and reduces cationic disorder to promote the Li+ diffusion and enhance the rate capability, but also stabilizes the oxygen skeleton, inhibits oxygen loss, and suppresses the migration of transition metal ions to improve the cyclic performance. As a result, Li1.18Na0.02(Mn0.54Ni0.13Co0.13)0.98Mo0.02O2 delivers 122.8 mAh.g−1 at 5 C and 262.9 mAh.g−1 at 0.2 C, retaining 90% capacity after 150 cycles.
•The doped Na+ expands the layer spacing and stabilizes the structure.•The doped Mo6+ stabilizes the oxygen skeleton and inhibits the oxygen loss.•Mo6+ results in more Mn3+ to improve conductivity and enhance the interface reaction.•The Na-Mo co-doped sample has a high capacity of 262.9 mAh g−1 at 0.2 C.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The frequency of extreme weather events, such as drought, is increasing under climate change in some areas. Grassland ecosystems are extremely sensitive to drought. Here we sought to determine which ...vegetation types are the most vulnerable drought within the Xilinguole grasslands of Inner Mongolia and to establish methods to quantitatively evaluate the effects of different drought levels on grassland productivity and economic losses. Over the past 20 years, the total annual precipitation in the Xilinguole League decreased by 24–52%, resulting in a reduction in annual pasture yield of 31–237 kg/ha and a loss of livestock grazing capacity of 3–20 head/10 ha, causing 4–26 billion yuan in direct economic losses. Across the league, 78% of drought-induced direct economic losses were concentrated in ecologically vulnerable areas, including sandy and desert grasslands and typical grasslands at the northern end and in southwestern areas. Grassland net primary productivity (NPP) was sensitive to and significantly affected by drought. As the standardised precipitation evapotranspiration index (SPEI) drought level increased, NPP loss rate increased significantly by more than 20% for each drought level. The effects of increasing drought on NPP varied within grassland types, and the effects of a given drought level were different across grassland types. Typical grasslands suffered high losses at all drought stages. Meadow grasslands adjusted relatively well to drought as the rate of grassland NPP loss changed relatively slowly with increasing drought. Desert grasslands were less affected by light-to-moderate drought than by moderate-to-severe drought. This study provides a scientific basis for improving ecosystem resilience and drought prevention and management.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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