Search

This article introduces a novel approach that unifies two types of models: one is the continuous‐time jump‐diffusion used to model high‐frequency market financial data, and the other is discrete‐time GQARCH for modeling low‐frequency financial data by embedding the discrete GQARCH structure with jumps in the instantaneous volatility process. This model is named GQARCH‐Itô‐Jumps model. Quasi‐likelihood functions for the low‐frequency GQARCH structure are developed for the parametric estimations. In the quasi‐likelihood functions, for high‐frequency financial data, the realized range‐based estimations are adopted as the 'observations', rather than the realized return‐based volatility estimators which entail the loss of intra‐day information of the price movements. Meanwhile, the asymptotic properties are mainly established for the proposed estimators in the case of finite activity jumps. Moreover, simulation studies and some financial data are implemented to check the finite sample performance of the proposed methodology. [ABSTRACT FROM AUTHOR]

This study focuses on the surface modification of substrates using a poly(N,N‐dimethyl‐N‐(ethoxycarbonylmethyl)‐N‐[2′‐(methacryloyloxy) ethyl]‐ammonium chloride‐co‐3‐(trimethoxysilyl)propylmethacrylate) P(CBMAE‐co‐TMSPMA) and ethyl orthosilicate (TEOS). By covalently bonding the Si‐OH pendant of the copolymer with hydroxyl residues on the material's surface, a stable polymer coating is formed. The properties of P(CBMAE‐co‐TMSPMA) coatings were evaluated using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscope (SEM), and contact angle (CA) meter. The addition of TEOS allows for the regulation of surface roughness. With the increase of TEOS content, the contact angle of underwater oil first increased and then decreased. The water contact angles were 8°, the underwater superoleophobic contact angle reached 168°, and the number of adherent platelets and Escherichia coli were significantly reduced to 7.5% and 5% on the surface of the coating, respectively. After undergoing simultaneous hydrolysis, the superoleophobic contact angle of P(CBMAE‐co‐TMSPMA)/SiO2 coating further increased to 174°. These interesting and robust properties make them promising candidates for biomedical applications. Highlights: The underwater superoleophobic coating (contact angles of 174°).The P(CBMAE‐co‐TMSPMA)/SiO2 coating with excellent resistance to oil adhesion.Solve the hydroxyl residue problem.The coating resistance to E. coli and platelet adhesion. [ABSTRACT FROM AUTHOR]

In Dunaliella tertiolecta, a microalga renowned for its extraordinary tolerance to high salinity levels up to 4.5 M NaCl, the mechanisms underlying its stress response have largely remained a mystery. In a groundbreaking discovery, this study identifies a choline dehydrogenase enzyme, termed DtCHDH, capable of converting choline to betaine aldehyde. Remarkably, this is the first identification of such an enzyme not just in D. tertiolecta but across the entire Chlorophyta. A 3D model of DtCHDH was constructed, and molecular docking with choline was performed, revealing a potential binding site for the substrate. The enzyme was heterologously expressed in E. coli Rosetta (DE3) and subsequently purified, achieving enzyme activity of 672.2 U/mg. To elucidate the role of DtCHDH in the salt tolerance of D. tertiolecta, RNAi was employed to knock down DtCHDH gene expression. The results indicated that the Ri-12 strain exhibited compromised growth under both high and low salt conditions, along with consistent levels of DtCHDH gene expression and betaine content. Additionally, fatty acid analysis indicated that DtCHDH might also be a FAPs enzyme, catalyzing reactions with decarboxylase activity. This study not only illuminates the role of choline metabolism in D. tertiolecta's adaptation to high salinity but also identifies a novel target for enhancing the NaCl tolerance of microalgae in biotechnological applications. [ABSTRACT FROM AUTHOR]

The lower floors of the multi‐storey structure can be impacted by the debris from the upper floor caused by gas and bomb explosion, which may induce damage or failure of the impacted substructure and lead to progressive collapse of large‐scale structure. The behavior of the frame with a steel beam and two adjacent beam‐column joints was numerically analyzed when the beam was impacted at midspan by various combinations of impact mass and velocity. The failure mode of the joints, the impact load and midspan displacement were analyzed. It shows that the beam‐column joint fails prior to the beam under all impact loading scenarios. The residual bearing capacity of the frame was also studied by statically pushing‐down the substructure after impact loading. A damage index was proposed using the residual capacity of the frame after impact loading divided by the static capacity of the joint without impact loading, and four damage levels, i.e., the minor damage, medium damage, severe damage, and collapse, were defined by the damage index. The boundaries of different damage levels of the frame under various impact loads were fitted, and it can be used to evaluate the damage level of the frame subjected to possible impact loads. [ABSTRACT FROM AUTHOR]

Accurate measurement data are a basic prerequisite for effective structural health monitoring (SHM). However, data loss are inevitable in the long‐term monitoring of large‐scale structures. To solve this problem, this research proposes a transformer‐based generative adversarial network (GAN) to reconstruct lost measurements from observed measurements. The generator of GAN is an encoder‐decoder structure using transformer as the backbone combined with discrete wavelet transform. Skip connections are used between the encoder part and decoder part to promote multi‐scale information flow. A novel discriminator is designed to assess the reality of wavelet spectra of reconstructed samples. To deceive the discriminator, the generator must generate samples that are accurate over the full frequency band. The developed model is used to reconstruct linear responses of a footbridge under pedestrian excitations and nonlinear responses of a suspension bridge under typhoon events. Experimental results demonstrate that lost responses can be reconstructed accurately, even when a large proportion of data are lost. The effectiveness of the proposed method is further verified by comparing the reconstruction accuracy of the proposed model with those of other three state‐of‐the‐art models. The results demonstrate that an improved performance of applying the proposed approach for dynamic structural response reconstruction is achieved and validated with in‐field testing data under ambient and extreme excitation conditions. [ABSTRACT FROM AUTHOR]

MADS transcription factors are involved in the regulation of fruit development and carotenoid metabolism in plants. However, whether and how carotenoid accumulation is regulated by algal MADS are largely unknown. In this study, we first used functional complementation to confirm the functional activity of phytoene synthase from the lutein‐rich Dunaliella sp. FACHB‐847 (DbPSY), the key rate‐limiting enzyme in the carotenoid biosynthesis. Promoters of DbPSY and DbLcyB (lycopene β‐cyclase) possessed multiple cis‐acting elements such as light‐, UV‐B‐, dehydration‐, anaerobic‐, and salt‐responsive elements, W‐box, and C‐A‐rich‐G‐box (MADS‐box). Meanwhile, we isolated one nucleus‐localized MADS transcription factor (DbMADS), belonging to type I MADS gene. Three carotenogenic genes, DbPSY, DbLcyB, and DbBCH (β‐carotene hydroxylase) genes were upregulated at later stages, which was well correlated with the carotenoid accumulation. In contrast, DbMADS gene was highly expressed at lag phase with low carotenoid accumulation. Yeast one‐hybrid assay and dual‐luciferase reporter assay demonstrated that DbMADS could directly bind to the promoters of two carotenogenic genes, DbPSY and DbLcyB, and repress their transcriptions. This study suggested that DbMADS may act as a negative regulator of carotenoid biosynthesis by repressing DbPSY and DbLcyB at the lag phase, which provide new insights into the regulatory mechanisms of carotenoid metabolism in Dunaliella. [ABSTRACT FROM AUTHOR]

Reliability analysis of bridges is essential for the design of civil engineering structures. The classical methods, such as Monte Carlo Simulation (MCS) and subset simulation techniques, may provide accurate results. However, since the finite element model of the large‐scale civil engineering structures usually consists of a large number of degrees of freedom, structural reliability analysis of such structures is time‐consuming and computational intensive, which may restrict the use of these methods. This paper proposes a novel method for the reliability analysis of bridge under different types of loads by combining Polynomial Chaos (PC) and subset simulation techniques. The surrogate model of the limit state function is approximated by using the PC expansion, in which the PC coefficients are obtained from the least‐squares method. The subset simulation with a PC‐based surrogate model is then used to estimate the rare failure probability. Reliability analyses of bridge structures under different loading types, that is, static load, dynamic moving load, and seismic load are performed. Studies by using the MCS method and the classical subset simulation are also conducted, and the results from the proposed approach are compared with those from MCS and subset simulation to demonstrate the accuracy and efficiency of the proposed method. [ABSTRACT FROM AUTHOR]

Oil contamination is problematic in subaqueous environments. Here, a cationic poly(N,N‐dimethyl‐N‐(ethoxycarbonylmethyl)‐N‐[2′‐(methacryloyloxy)ethyl]‐ ammonium chloride) (PCBMAE) was synthesized, and a one‐step approach of dopamine‐assisted codeposition was used to generate PCBMAE/polydopamine (PDA) superhydrophilic and underwater superoleophobic coatings coated on a stainless steel mesh for oil/water separation. The structures, surface morphologies, and properties of the coatings were analyzed by IR, SEM, TGA, and contact angle measurements. During deposition at a PCBMAE and DA mass ratio of 1:1, PCBMAE/PDA mixture particles uniformly adhered to the skeletons of the mesh, increased the surface roughness, created enriched surface micro/nanostructures, and reduced the surface energy of the coating. This endowed the metal mesh with superhydrophilicity and underwater superoleophobicity (oil contact angle 163°) without blocking the mesh, and the deposition density was 0.26 mg/cm2. The separation efficiency of the coated mesh was 99.6% for the first castor oil/water separation and dropped to 98.0% after 5 cycles. After 25 cycles, the separation efficiency was still higher than 95%. The PCBMAE/PDA codeposited mesh exhibited high oil/water separation efficiency, stable mechanical properties, and weather stability under different harsh environments, making it a promising separation material for future industrial applications. [ABSTRACT FROM AUTHOR]

This study experimentally examines the effect of rubber aggregate size on the static and dynamic behavior of rubberized concrete. Rubberized concrete specimens were prepared with different maximum rubber aggregate sizes ranging from 1 to 3 mm to 3 to 5 mm while the rubber content was kept constant at 15% by volume. The dynamic compressive behavior of rubberized concrete was investigated by using split Hopkinson pressure bar (SHPB) tests. The experimental results have shown that rubberized concrete with smaller rubber aggregates showed higher static compressive strength as compared to that with larger rubber aggregates. Meanwhile, the rubber aggregate size did not considerably affect the density of rubberized concrete. The use of smaller rubber aggregate size mitigated the slump reduction of rubberized concrete. Rubberized concrete exhibited obvious sensitivity to strain rate and those with larger rubber aggregates showed higher strain rate sensitivity. The progressive damage of rubberized concrete showed more ductile behavior with bulging failure, which was different from the typical concrete under compression. In general, the use of smaller rubber aggregate size was beneficial to the static compressive strength but less effective to the dynamic compressive strength of rubberized concrete as compared to those with larger rubber aggregates. [ABSTRACT FROM AUTHOR]

Dunaliella salina can accumulate a large amount of β‐carotene which is generally considered to be its terminal product of carotenoid metabolism. In this study, it was proved that D. salina has the ketolase (DsBKT) of catalyzing the synthesis of astaxanthin, the downstream products of β‐carotene. Therefore, the reason why D. salina does not synthesize astaxanthin is the purpose of this study. The enzymatic activity of DsBKT was detected by functional complementation assays in Escherichia coli, results showed that DsBKT had efficient ketolase activity toward β‐carotene and zeaxanthin to produce astaxanthin, indicating that there were complete astaxanthin‐producing genes in Dunaliella. Unlike the induced expression of Lycopene cyclase (catalyzing β‐carotene synthesis) under salt stress, the expression of DsBKT was very low under both normal and stress conditions, which may be the main reason why D. salina cannot accumulate astaxanthin. On the contrary, with the astaxanthin‐rich Haematococcus pluvialis as a control, its BKT gene was significantly upregulated under salt stress. Further study showed that DsBKT promoter had strong promoter ability and could stably drive the expression of ble‐egfp in D. salina. Obviously, DsBKT promoter is not the reason of DsBKT not being expressed which may be caused by Noncoding RNA. [ABSTRACT FROM AUTHOR]

An isochromene synthesis is developed utilizing a cascade reaction involving a CuI catalyzed coupling reaction between an alkyne and diazoacetate followed by allenoate isomerization and subsequent oxa‐Michael addition. The cascade sequence was also demonstrated for the synthesis of naphthalenes. Furthermore, the methodology developed herein was applied toward a stereoselective synthesis of pyranonaphthoquinone kalafungin. [ABSTRACT FROM AUTHOR]

The development of new‐type memristors with special performance is of great interest. Herein, an inorganic‐organic hybrid crystalline polyoxometalate (POM) with usual dynamic structures is reported and used as active material for fabricating memristor with unique temperature‐regulated resistive switching behaviors. The hybrid POM not only exhibits tunable thermochromic properties, but also thermal‐induced reversible aggregation and disaggregation reactions, leading to reversible structural transformations in SCSC fashion. Further, the memory device using the hybrid POM as active layer exhibits uncommon performance, which can keep resistive switching silent in the low temperature range of 30–150 °C, but show nonvolatile memory behavior in the high temperature range of 150–270 °C. Particularly, the silent and working states at three special temperatures (30, 150 and 270 °C) can be monitored by chromism. The correlation between structure and resistive switching property of the material has been discussed. The work demonstrates that crystalline inorganic‐organic hybrid POMs are promising materials for making memristors with superior performance. [ABSTRACT FROM AUTHOR]

Background & Aims: Nucleotides with add‐on interferon treatment (NUC‐IFN) provide significantly higher rates of hepatitis B surface antigen (HBsAg) loss in patients with chronic hepatitis B (CHB). This study aimed to investigate the sustainability of HBsAg loss and the prevention of clinical relapse. Methods: Patients with CHB who achieved HBsAg loss and HBV DNA levels <20 IU/ml after IFN or NUC‐IFN therapy were enrolled and followed up for 96 weeks. The primary outcome was HBsAg negativity without viremia at week 96. Secondary outcomes included virological or clinical relapse and predictors of relapse. Results: 420 patients were included in intention‐to‐treat analysis with 290 and 130 in the IFN and NUC‐IFN groups respectively. At week 96, the intention‐to‐treat analysis revealed similar outcomes between groups, including HBsAg seroreversion (24.83% vs. 23.08%, P =.70), viremia (16.90% vs 13.08%, P =.32) and clinical relapse (11.38% vs 10.00%, P =.68); the per‐protocol analyses also showed HBsAg seroreversion, viremia and clinical relapse in IFN group (15.50%, 6.59% and 0.39%) did not differ from those in NUC‐IFN group (15.25%, 4.24% and 0.85%, P >.05). These outcomes were similar between patients who received entecavir and those who received telbivudine/lamivudine/adefovir before the combination therapy. In NUC‐IFN‐treated patients, fibrosis regression was observed at week 96. Baseline HBsAb negativity was independent predictors of HBsAg sero‐reversion and recurrence of viremia in IFN treated group. Conclusion: NUC‐IFN and IFN therapies are equally effective in achieving sustained functional cure and fibrosis regression. (ClinicalTrials.gov, Number NCT02336399). [ABSTRACT FROM AUTHOR]

MG53 is an important membrane repair protein and partially protects bone marrow multipotent adult progenitor cells (MAPCs) against oxidized low‐density lipoprotein (ox‐LDL). The present study was to test the hypothesis that the limited protective effect of MG53 on MAPCs was due to ox‐LDL‐induced reduction of MG53. MAPCs were cultured with and without ox‐LDL (0‐20 μg/mL) for up to 48 hours with or without MG53 and antioxidant N‐acetylcysteine (NAC). Serum MG53 level was measured in ox‐LDL‐treated mice with or without NAC treatment. Ox‐LDL induced significant membrane damage and substantially impaired MAPC survival with selective inhibition of Akt phosphorylation. NAC treatment effectively prevented ox‐LDL‐induced reduction of Akt phosphorylation without protecting MAPCs against ox‐LDL. While having no effect on Akt phosphorylation, MG53 significantly decreased ox‐LDL‐induced membrane damage and partially improved the survival, proliferation and apoptosis of MAPCs in vitro. Ox‐LDL significantly decreased MG53 level in vitro and serum MG53 level in vivo without changing MG53 clearance. NAC treatment prevented ox‐LDL‐induced MG53 reduction both in vitro and in vivo. Combined NAC and MG53 treatment significantly improved MAPC survival against ox‐LDL. These data suggested that NAC enhanced the protective effect of MG53 on MAPCs against ox‐LDL through preventing ox‐LDL‐induced reduction of MG53. [ABSTRACT FROM AUTHOR]

Host‐guest encapsulation of functional organic dye into a porous metal‐organic framework can give rise to the development of new functional materials. In this work, by intercalating the stilbazolium‐type dye (DEAST)I (4′‐diethylamino‐N‐methyl stilbazolium) into four lanthanide layered metal‐organic complexes (Ln‐LMOCs), i. e. {[Ln(BTB)(H2O)2]⋅3(DMF)⋅2(H2O)}n (Ln=La (1), Nd (2), Sm (3), Er (4)), four responsive (DEAST)I@Ln‐LMOC composites have been prepared, serving as multifunctional performance platform. The core–shell structures of (DEAST)I@Ln‐LMOC composites have been fully characterized by IR, UV/Vis, PXRD, SEM, TEM, TGA and ESR. Significantly, after intercalation of dyes, the (DEAST)I@Ln‐LMOC composites exhibit enhanced luminescent sensing properties in detecting Fe3+ with much higher water stabilities. The luminescent sensing behavior stems from the fluorescence resonance energy transfer (FRET) from the π‐electron‐rich BTB ligands to the Fe3+, and their higher water stabilities are induced by electrostatic interactions and lower porosity. Specially, the characteristic emissions of Sm3+ will not be affected after the encapsulation guest dyes, which provide a theoretical guide for the modulation of luminescence devices. Finally, better ion conductivities and diminished photocurrents can be achieved after the embedding of the functional organic dye. In all, the formation of (DEAST)I@Ln‐LMOC composites with core–shell structures can be utilized as a multifunctional platform with good stability. [ABSTRACT FROM AUTHOR]

Liver necroinflammation is the indicator for treating patients with chronic hepatitis B (CHB) infection. However, there is no suitable non‐invasive index for diagnosing liver necroinflammation. This study aimed to create a non‐invasive index to predict liver necroinflammation in patients who lack clear‐cut clinical inflammation parameters. Patients who were hepatitis B e antigen (HBeAg)‐negative and underwent liver histological diagnosis, had a normal or minimally increased alanine aminotransferase (ALT) level were enrolled. Liver necroinflammation was defined as histological active index ≥4. A logistic regression model (LRM) was established based on the parameters independently associated with liver necroinflammation. Of all 550 patients, 36.73% had necroinflammation. In patients with an abnormal ALT level, the rate of necroinflammation was 52.49%. The area under the curve (AUC) of the ALT level for predicting necroinflammation was 0.655 (95% confidence interval [CI], 0.609‐0.702), and that of the HBV DNA level ≥2000 IU/mL combined with an abnormal ALT level was 0.618. By using the LRM, the AUC improved to 0.769 (95% CI, 0.723‐0.815) with a Youden index of 0.519 and diagnostic accuracy of 75.3%. The cutoff value ≥0.7 in the LRM had a specificity of 97.4% and positive predictive value of 85.0% for predicting necroinflammation. By using the cutoff value <0.15 in the LRM, the presence of necroinflammation could be excluded with a negative predictive value of 90.8%. This study indicated that the LRM can be used to effectively diagnose liver necroinflammation in HBeAg‐negative patients with CHB who have normal or minimally elevated ALT levels. [ABSTRACT FROM AUTHOR]

Hepatitis B surface antigen (HBsAg) loss is considered a functional cure in chronic hepatitis B (CHB). However, the durability of HBsAg loss after stopping treatment remains unknown. This study aimed to assess the sustained functional cure achieved by interferon therapy in hepatitis B envelope antigen (HBeAg)‐negative CHB patients. In this prospective study, 176 HBeAg‐negative CHB patients with functional cure were enrolled for 12 weeks of cessation treatment, and treatment information and baseline data were collected. Hepatitis B virus (HBV) biomarkers and clinical biochemical indicators were evaluated every 3 months; liver imaging examinations were performed every 3‐6 months during the 48‐week follow‐up. The sustained functional cure was evaluated. After the 48‐week follow‐up, the sustained functional cure rate was 86.63%. The cumulative rates of HBsAg reversion and HBV DNA reversion were 12.79% and 2.33%, respectively. Consolidation treatment ≥ 12 weeks after HBsAg loss achieved a significantly higher rate of sustained functional cure and significantly lower rate of HBsAg reversion than consolidation treatment < 12 weeks (76.19% vs 90.00%, P = 0.022 and 23.81% vs 9.23%, P = 0.014, respectively). Patients with hepatitis B surface antibody (HBsAb) had higher rate of sustained functional cure than patients achieving HBsAg loss but without HBsAb (89.86% vs 73.53%, P = 0.012). Consolidation treatment ≥ 12 weeks (odds ratio [OR] 16.478; 95% confidence interval [CI], 2.135‐127.151; P = 0.007) and high HBsAb levels (OR 8.312; 95% CI, 1.824‐37.881; P = 0.006) were independent predictors of sustained functional cure. Results suggested that 12 weeks of consolidation therapy after HBsAg clearance and elevated HBsAb levels help to improve functional cure. [ABSTRACT FROM AUTHOR]

Endothelial progenitor cells (EPCs) are a group of heterogeneous cells in bone marrow (BM) and blood. Ischaemia increases reactive oxygen species (ROS) production that regulates EPC number and function. The present study was conducted to determine if ischaemia‐induced ROS differentially regulated individual EPC subpopulations using a mouse model concomitantly overexpressing superoxide dismutase (SOD)1, SOD3 and glutathione peroxidase. Limb ischaemia was induced by femoral artery ligation in male transgenic mice with their wild‐type littermate as control. BM and blood cells were collected for EPCs analysis and mononuclear cell intracellular ROS production, apoptosis and proliferation at baseline, day 3 and day 21 after ischaemia. Cells positive for c‐Kit+/CD31+ or Sca‐1+/Flk‐1+ or CD34+/CD133+ or CD34+/Flk‐1+ were identified as EPCs. ischaemia significantly increased ROS production and cell apoptosis and decreased proliferation of circulating and BM mononuclear cells and increased BM and circulating EPCs levels. Overexpression of triple antioxidant enzymes effectively prevented ischaemia‐induced ROS production with significantly decreased cell apoptosis and preserved proliferation and significantly increased circulating EPCs level without significant changes in BM EPC populations, associated with enhanced recovery of blood flow and function of the ischemic limb. These data suggested that ischaemia‐induced ROS was differentially involved in the regulation of circulating EPC population. [ABSTRACT FROM AUTHOR]

The removal of C2H2 and C2H6 from C2H4 streams is of great significance for feedstock purification to produce polyethylene and other commodity chemicals but the simultaneous adsorption of C2H6 and C2H2 over C2H4 from a ternary mixture has never been realized. Herein, a robust metal–organic framework, TJT‐100, was designed and synthesized, which demonstrates remarkably selective adsorption of C2H2 and C2H6 over C2H4. Breakthrough experiments show that TJT‐100 can be used as an adsorbent for high‐performance purification of C2H4 from a ternary mixture of C2H2/C2H4/C2H6 (0.5:99:0.5) to afford a C2H4 purity greater than 99.997 %, beyond that required for ethylene polymerization. Computational studies reveal that the uncoordinated carboxylate oxygen atoms and coordinated water molecules pointing towards the pore can trap C2H2 and C2H6 through the formation of multiple C−H⋅⋅⋅O electrostatic interactions, while the corresponding C2H4–framework interaction is unfavorable. [ABSTRACT FROM AUTHOR]

Selective introduction of fluorine into molecules by the cleavage of inert C−H bonds is of central academic and synthetic interest, yet remains challenging. Given the central role of alcohols in organic chemistry as the most ubiquitous building blocks, a versatile and selective C(sp3)−H and C(sp2)−H fluorination of simple alcohols, enabled by novel designed exo‐directing groups, is described. C(sp2)−H bond fluorination was achieved by using a simple acetone oxime as auxiliary, whereas a new, modular and easily accessible bidentate auxiliary was developed for the efficient and site‐selective fluorination of various primary methyl, methylene, and benzylic C(sp3)−H bonds. Fluorinated alcohols can readily be accessed by the removal of auxiliaries, and significantly expands the synthetic prospect of the present procedure. A versatile and selective C(sp3)−H and C(sp2)−H fluorination of simple alcohols, enabled by an exo‐directing group (DG) is described. C(sp2)−H bond fluorination was achieved by using simple acetone oxime as an auxiliary, whereas a new and modularly accessible bidentate auxiliary was developed for the efficient and site‐selective fluorination of C(sp3)−H bonds. The auxiliary is removable and demonstrates broad substrate scope and excellent selectivity. [ABSTRACT FROM AUTHOR]

Four (triphenyl)phosphonium‐based quaternary phosphorus salts with different substituents (varying from methyl to n‐butyl) were selected to be structural directed agents (SDAs) to construct four iodocuprate(I) hybrids via solution method, i.e., [(PPh3Me)(Cu3I4)]n (1), [(PPh3Et)(Cu3I4)]n (2), (PPh3iPr)2(Cu2I4) (3), [(PPh3nBu)(Cu3I4)]n (4). The inorganic iodocuprates in 1, 2 and 4 are 1‐D (Cu3I4)nn– chains constructed from Cu5I11 units, but (Cu2I4)2– in 3 is a di‐nuclear cluster. Interestingly, the strength of Cu···Cu and π–π stacking interactions are weakened with the lengthening of alkyl groups on P‐atom. The best water stability of 4 can be ascribed to the better hydrophobicity of n‐butyl group, which deters the dispersing of organic and inorganic moieties and as a result, inhibit hydrolysis reaction. Furthermore, all compounds exhibit typical reversible luminescent thermochromic behaviors, among which 4 exhibits blue emission and the quenching of higher energy (HE) zone in 1 and 2 are led by strong π–π stacking interactions. Besides, effective and repeatable photocurrent responses can be detected in these compounds. In all, by systematically introducing alkyl groups into (triphenyl)phosphonium as SDAs to prepare hybrid iodocuprates, we can find that the longer alkyl groups can achieve stronger tunable PL materials with enhanced water stabilities. Four iodocuprate(I) hybrids have been prepared by using quaternary phosphorus salts as SDAs. The weakening of Cu···Cu and π–π stacking interactions with the lengthening of alkyl groups on the P‐atom is relative to their water stabilities and luminescent thermochromic behaviors. The proper length of alkyl group on (triphenyl)phosphonium in hybrid iodocuprates can achieve strong blue PL materials with enhanced water stability. [ABSTRACT FROM AUTHOR]

Discrete‐time stochastic volatility models play a key role in the analysis of financial time series. However, the parametric assumption of conditional distribution for asset returns, given the volatility, has been questioned. When the conditional distribution is unknown and unspecified, in this paper, a maximum‐likelihood estimation approach for the semiparametric stochastic volatility models is proposed based on kernel density estimation and hidden Markov models. Several numerical studies are conducted to evaluate the finite sample performance of the proposed estimation method. Implementation on empirical studies also illustrates the validity of the proposed method in practice. [ABSTRACT FROM AUTHOR]

Cu is a unique catalyst for CO2 electroreduction, since it can catalyze CO2 reduction to a series of hydrocarbons, alcohols, and carboxylic acids. Nevertheless, such Cu catalysts suffer from poor selectivity. High pressure of CO2 is considered to facilitate the activity and selectivity of CO2 reduction. Herein, a new strategy is presented for CO2 reduction with improved C2H4 selectivity on a Cu catalyst by using CO2 capture materials as the support at ambient pressure. N‐doped carbon (NxC) was synthesized through high‐temperature carbonization of melamine and l‐lysine. We observed that the CO2 uptake capacity of NxC depends on both the microporous area and the content of pyridinic N species, which can be controlled by the carbonization temperature (600–800 °C). The as‐prepared CuO/NxC catalysts exhibit a considerably higher C2H4 faradaic efficiency (36 %) than CuO supported on XC‐72 carbon black (19 %), or unsupported CuO (20 %). Moreover, there is a good linear relationship between the C2H4 faradaic efficiency and CO2 uptake capacity of the supports for CuO. The local high CO2 concentration near Cu catalysts, created by CO2 capture materials, was proposed to increase the coverage of CO intermediate, which is favorable for the coupling of two CO units in the formation of C2H4. This study demonstrates that pairing Cu catalysts with CO2 capture supports is a promising approach for designing highly effective CO2 reduction electrocatalysts. [ABSTRACT FROM AUTHOR]

Generally, the Al-PTFE (polytetrafluoroethylene) is thought to be inert under quasi-static or static loads. However, it was found that Al-PTFE would initiate under quasi-static compression after a specific heat treatment procedure and the opening fracture plays a crucial role in the initiation. A unique micrographic fracture pattern which showed unstable crack propagation and a ductile-to-brittle transition was observed at openning cracks by SEM. Combining the observed microstructure with the stress distribution at the path of crack propagation derived from numerical simulation, a mechanism was proposed to explain the formation of 'hot-spots' at the crack tip. The temperature rise at the crack tip was estimated to be at least 612 °C, which is high enough to ignite the Al-PTFE composite. [ABSTRACT FROM AUTHOR]

In the carotenoid biosynthesis, lycopene β-cyclase (LCYb) is a key regulatory enzyme involved in the conversion of lycopene into β-carotene. Under stress conditions, such as high salinity, high light and nutrient deprivation, large amounts of β-carotene can be accumulated in Dunaliella bardawil. To study on the molecular responses of salt stress in D. bardawil is of great significance to reveal the mechanisms of salt tolerance and engineer crop plants to be salt-tolerant. In this study, the full-length coding sequence of lcyb from D. bardawil ( Dblcyb, GenBank: KX218392) was isolated by transcriptome sequencing. Then, the genomic sequence, promoter and terminator regions of Dblcyb were isolated by genome walking. The Dblcyb promoter (GenBank: KX218393) contained several typical transcription boxes, multiple light response elements and a salt-regulated element (SRE, GT1GMSCAM4). Dbpsy and Dblcyb responsible for β-carotene biosynthesis in D. bardawil was shown to be up-regulated under salt stress and their promoters contained the common SRE. By element deletion analysis and using Ble-EGFP as the reporter, the salt-inducible SRE was confirmed to confer salt-induced expression of Dblcyb promoter. It was indicated that the salt-regulated expression of Dblcyb may be attributed to the salt-responsive element (GT1GMSCAM4) and the GT-rich region in its genomic sequence. [ABSTRACT FROM AUTHOR]

Objective To analyze the local field potential ( LFP) of the anterior nucleus of the thalamus ( ANT) of epileptic rats using the Generic Osorio-Frei algorithm ( GOFA), and to determine the ability of the ANT LFP to predict clinical seizures in temporal lobe epilepsy. Methods GOFA is an advanced real-time technique used to detect and predict seizures. In this article, GOFA was utilized to process the electrical signals of ANT and the motor cortex recorded in 12 rat models of temporal lobe epilepsy ( TLE) induced via the injection of kainic acid into the unilateral hippocampus. The electroencephalography ( EEG) data included (1) 161 clinical seizures (each contained a 10-min segment) involving the ANT and cortical regions and (2) one hundred three 10-min segments of randomly selected interictal (no seizure) data. Results Minimal false-positives (0.51 ± 0.36/h) and no false-negatives were detected based on the ANT LFP data processed using GOFA. In ANT LFP, the delay from electrographic onset ( EO) to automated onset ( AO) was 1.24 ± 0.47 s, and the delay from AO to clinical onset ( CO) was 7.73 ± 3.23 s. The AO time occurred significantly earlier in the ANT than in the cortex (p = 0.001). In 75.2% of the clinical onsets predicted by ANT LFP, it was 1.37 ± 0.82 s ahead of the prediction of cortical potentials ( CPs), and the remainder were 0.84 ± 0.31 s slower than the prediction of CPs. Significance ANT LFP appears to be an optimal option for the prediction of seizures in temporal lobe epilepsy. It was possible to upgrade the responsive neurostimulation system to emit electrical stimulation in response to the prediction of epileptic seizures based on the changes in the ANT LFP. [ABSTRACT FROM AUTHOR]

The reaction of Keggin-type polyoxometalate (POM) units, transition-metal (TM) ions, and a rigid bis(imidazole) ligand (1,4-bis(1-imidazolyl)benzene (bimb)) in a hydrothermal environment led to the isolation of four new POM-based metal-organic networks, [H2L][CuL][SiW12O40]⋅2 H2O ( 1), [H2L]2[Co(H2O)3L][SiW11CoO39]⋅6 H2O ( 2), KH[CuL]2[SiW11CoO39(H2O)]⋅2 H2O ( 3), and [CuL]4[GeW12O40]⋅H2O ( 4; L=bimb). All four compounds were characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, powder X-ray diffraction, and single-crystal X-ray diffraction. Compounds 1 and 3 are new 3D networks with 1D channels. Compounds 2 and 4 contain 2D networks, which further stack into 3D supramolecular networks. The contributions of pH value, the negative charge of the POM, and the TM coordination modes to the construction of 3D networks were elucidated by comparing the synthetic conditions and structures of compounds 1- 4. The photocatalytic properties of compounds 1- 4 were investigated using methylene blue (MB) degradation under UV light. All compounds showed good catalytic activity and structural stability. The possible catalytic mechanism was discussed on the basis of active-species trapping experiments. The different photocatalytic activities of compounds 1- 4 were explained by comparison of the band gaps of different POM species and different packing modes of POM units in these hybrid compounds. [ABSTRACT FROM AUTHOR]

A facile and high-yielding one-step conversion of dihydroartemisinic acid into dihydro- epi-deoxyarteannuin B, a natural product and a pivotal compound in the synthesis of several other natural products isolated from Artemisia annua L., was developed after the systematic examination of several potentially applicable conditions. The transformation, most satisfactorily effected with Pd(OAc)2/CuCl2/MnO2, makes it possible to access many known potent antimalarial trioxanes from readily available artemisinic acid. Some interesting cases of differentiation between the carbonyl groups are also presented. [ABSTRACT FROM AUTHOR]

Cell therapy with bone marrow stem cells ( BMSCs) remains a viable option for tissue repair and regeneration. A major challenge for cell therapy is the limited cell survival after implantation. This study was to investigate the effect of oxidized low-density lipoprotein (ox- LDL, naturally present in human blood) on BMSC injury and the effect of MG53, a tissue repair protein, for the improvement of stem cell survival. Rat bone marrow multipotent adult progenitor cells ( MAPCs) were treated with ox- LDL, which caused significant cell death as reflected by the increased LDH release to the media. Exposure of MAPCs to ox- LDL led to entry of fluorescent dye FM1-43 measured under confocal microscope, suggesting damage to the plasma membrane. Ox- LDL also generated reactive oxygen species ( ROS) as measured with electron paramagnetic resonance spectroscopy. While antioxidant N-acetylcysteine completely blocked ROS production from ox- LDL, it failed to prevent ox- LDL-induced cell death. When MAPCs were treated with the recombinant human MG53 protein (rh MG53) ox- LDL induced LDH release and FM1-43 dye entry were significantly reduced. In the presence of rh MG53, the MAPCs showed enhanced cell survival and proliferation. Our data suggest that membrane damage induced by ox- LDL contributed to the impaired survival of MAPCs. rh MG53 treatment protected MAPCs against membrane damage and enhanced their survival which might represent a novel means for improving efficacy for stem cell-based therapy for treatment of diseases, especially in setting of hyperlipidemia. [ABSTRACT FROM AUTHOR]

SUMMARY In most of the seismic design provision, the concept of strength reduction factor has been developed to account for inelastic behavior of structures under seismic excitations. Most recent studies considered soil-structure interaction (SSI) in inelastic response analysis are mainly based on idealized structural models of single degree-of-freedom (SDOF) systems. However, an SDOF system might not be able to well capture the SSI and structural response characteristics of real multiple degrees-of-freedom (MDOF) systems. In this paper, through a comprehensive parametric study of 21600 MDOF and its equivalent SDOF (E-SDOF) systems subjected to an ensemble of 30 earthquake ground motions recorded on alluvium and soft soils, effects of SSI on strength reduction factor of MDOF systems have been intensively investigated. It is concluded that generally, SSI reduces the strength reduction factor of both MDOF and more intensively SDOF systems. However, depending on the number of stories, soil flexibility, aspect ratio and inelastic range of vibration, the strength reduction factor of MDOF systems could be significantly different from that of E-SDOF systems. A new simplified equation, which is a function of fixed-base fundamental period, ductility ratio, the number of stories, structure slenderness ratio and dimensionless frequency, is proposed to estimate strength reduction factors for MDOF soil-structure systems. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A new low-dimensional benzyl viologen/iodoargentate hybrid, [(BV)2(Ag5I9)] n ( 1) (BV2+ = benzyl viologen) was prepared. In 1, (Ag6I9) n2- chain exhibits a new type of one-dimensional chain constructed from vertex-sharing of Ag5I10 units, and its two-dimensional layer structure was constructed from C-H ···I hydrogen bonds. Strong luminescence at 404 nm can be detected in 1. DFT calculation suggests that 1 displays a reduced bandgap, which is led by a more dispersed LUMO band of BV2+ compared with MV2+ in [ MV(Ag2I4)] n. [ABSTRACT FROM AUTHOR]

Perhydrolysis of a sterically congested multifunctional epoxide was achieved in ethereal H2O2 with the aid of a recently developed Mo catalyst. The resulting hydroperoxide cyclized to give a 1,2,4-trioxane, which could be readily elaborated into qinghaosu and a range of novel analogues. Some of the compounds with two such trioxane moieties showed in vitro antimalarial activity comparable to or even better than that of artesunate or chloroquine. [ABSTRACT FROM AUTHOR]

SUMMARY Recently, several new optimum loading patterns have been proposed by researchers for fixed-base systems while their adequacy for soil-structure systems has not been evaluated yet. Through intensive dynamic analyses of multistory shear-building models with soil-structure interaction subjected to a group of 21 artificial earthquakes adjusted to soft soil design spectrum, the adequacy of these optimum patterns is investigated. It is concluded that using these patterns the structures generally achieve near optimum performance in some range of periods. However, their efficiency reduces as soil flexibility increases especially when soil-structure interaction effects are significant. In the present paper, using the uniform distribution of damage over the height of structures, as the criterion, an optimization algorithm for seismic design of elastic soil-structure systems is developed. The effects of fundamental period, number of stories, earthquake excitation, soil flexibility, building aspect ratio, damping ratio and damping model on optimum distribution pattern are investigated. On the basis of 30,240 optimum load patterns derived from numerical simulations and nonlinear statistical regression analyses, a new lateral load pattern for elastic soil-structure systems is proposed. It is a function of the fundamental period of the structure, soil flexibility and structural slenderness ratio. It is shown that the seismic performance of such a structure is superior to those designed by code-compliant or recently proposed patterns by researchers for fixed-base structures. Using the proposed load pattern in this study, the designed structures experience up to 40% less structural weight as compared with the code-compliant or optimum patterns developed based on fixed-base structures. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY Pounding between adjacent bridge structures with insufficient separation distance has been identified as one of the primary causes of damage in many major earthquakes. It takes place because the closing relative movement is larger than the structural gap provided between the structures. This relative structural response is controlled not only by the dynamic properties of the participating structures but also by the characteristics of the ground excitations. The consequence of the spatial variation of ground motions has been studied by researchers; however, most of these studies were performed numerically. The objective of the present research is to experimentally evaluate the influence of spatial variation of ground motions on the pounding behaviour of three adjacent bridge segments. The investigation is performed using three shake tables. The input spatially varying ground excitations are simulated based on the New Zealand design spectra for soft soil, shallow soil and strong rock using an empirical coherency loss function. Results confirm that the spatially nonniform ground motions increase the relative displacement of adjacent bridge girders and pounding forces. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The transcription factor Oct4 is critical to the pluripotency, self-renewal and differentiation of stem cells. The aim of the present study was to investigate the effects of high glucose (HG) on the cell cycle progression of bone marrow multipotent adult progenitor cells (MAPC) and Oct4 expression, as well as the underlying mechanisms. Rat MAPC were cultured in normal (5.5 mmol/L d-glucose) and HG (25.5 mmol/L d-glucose) media for up to 14 days. l- Glucose served as a high osmolarity control. Culture in HG media substantially increased the number of cells in the G0/ G1 phase and decreased the number in the S phase without changing the cell population in the G2 phase. Expression of the cell cycle regulatory protein p21 CIP/ WAF-1 (p21), but not that of p27 KIP-1 (p27), was significantly upregulated in cells cultured in HG media. Significant increases were seen in transforming growth factor (TGF)-β1 levels in cells and MAPC-conditioned medium in the presence of HG, and extracellular signal-regulated kinase (ERK) 1/2 phosphorylation was enhanced in cells cultured in the presence of HG medium without any changes in Akt phosphorylation. Neutralizing TGF-β1 antibody effectively prevented HG-induced increases in ERK1/2 phosphorylation, p21 expression and suppression of cell cycle progression of MAPC. Inhibiting ERK1/2 phosphorylation with PD98059 completely blocked HG-induced p21 expression and markedly reversed HG-induced inhibition of cell cycle progression in MAPC. The HG-induced suppression of cell cycle progression was not accompanied by inhibition of cell proliferation or Oct4 expression in these cells. The data indicate that HG facilitates cell cycle arrest of rat MAPC through TGF-β1-induced activation of ERK1/2 signalling and p21 expression, and that Oct4 expression in MAPC is independent of the cell cycle and/or TGF-β1 or ERK1/2 signalling in HG medium. [ABSTRACT FROM AUTHOR]

A series of 1,2,4-trioxanes were synthesized in which the key peroxy bonds were installed through a molybdenum-catalyzed perhydrolysis of the epoxy rings. A core structure was identified that may serve as a promising lead structure for further investigations because of its high antimalarial activity (comparable to that of artesunate and chloroquine), apparent potential for scale-up and derivatization, and facile monitoring/tracing by using UV light. [ABSTRACT FROM AUTHOR]

Coherency functions are used to describe the spatial variation of seismic ground motions at multiple supports of long span structures. Many coherency function models have been proposed based on theoretical derivation or measured spatial ground motion time histories at dense seismographic arrays. Most of them are suitable for modelling spatial ground motions on flat-lying alluvial sites. It has been found that these coherency functions are not appropriate for modelling spatial variations of ground motions at sites with irregular topography ( Struct. Saf. 1991; (1):1-13). This paper investigates the influence of layered irregular sites and random soil properties on coherency functions of spatial ground motions on ground surface. Ground motion time histories at different locations on ground surface of the irregular site are generated based on the combined spectral representation method and one-dimensional wave propagation theory. Random soil properties, including shear modulus, density and damping ratio of each layer, are assumed to follow normal distributions, and are modelled by the independent one-dimensional random fields in the vertical direction. Monte-Carlo simulations are employed to model the effect of random variations of soil properties on the simulated surface ground motion time histories. The coherency function is estimated from the simulated ground motion time histories. Numerical examples are presented to illustrate the proposed method. Numerical results show that coherency function directly relates to the spectral ratio of two local sites, and the influence of randomly varying soil properties at a canyon site on coherency functions of spatial surface ground motions cannot be neglected. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

It is commonly understood that earthquake ground excitations at multiple supports of large dimensional structures are not the same. These ground motion spatial variations may significantly influence the structural responses. Similarly, the interaction between the foundation and the surrounding soil during earthquake shaking also affects the dynamic response of the structure. Most previous studies on ground motion spatial variation effects on structural responses neglected soil-structure interaction (SSI) effect. This paper studies the combined effects of ground motion spatial variation, local site amplification and SSI on bridge responses, and estimates the required separation distances that modular expansion joints must provide to avoid seismic pounding. It is an extension of a previous study ( Earthquake Engng Struct. Dyn. 2010; (3):303-323), in which combined ground motion spatial variation and local site amplification effects on bridge responses were investigated. The present paper focuses on the simultaneous effect of SSI and ground motion spatial variation on structural responses. The soil surrounding the pile foundation is modelled by frequency-dependent springs and dashpots in the horizontal and rotational directions. The peak structural responses are estimated by using the standard random vibration method. The minimum total gap between two adjacent bridge decks or between bridge deck and adjacent abutment to prevent seismic pounding is estimated. Numerical results show that SSI significantly affects the structural responses, and cannot be neglected. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This study was to investigate the effect of oxidized low-density lipoprotein (ox-LDL) on the behaviour of bone marrow stem cells and their endothelial differentiation as well as the underlying mechanisms. Adult rat bone marrow multipotent progenitor cells (MAPCs) were incubated with ox-LDL for up to 2 weeks. Ox-LDL treatment resulted in a time- and dose-dependent reduction of MAPC population in culture through a combination of decreased cell proliferation and increased apoptosis. The expression of stem cell marker Oct-4 was significantly suppressed in MAPCs by ox-LDL in a dose- and time-dependant manner. Endothelial differentiation of MAPCs was substantially inhibited by ox-LDL with markedly decreased expression of endothelial markers vWF, Flk-1 and CD31, as well as impaired in vitro vascular structure formation. Ox-LDL-induced apoptosis and inhibition of Oct-4 expression, cell proliferation and endothelial differentiation of MAPCs were associated with significant inhibition of Akt phosphorylation. Akt overexpression in MAPCs transfected with a constitutively active Akt completely reversed the effects of ox-LDL on MAPCs including enhanced apoptosis, decreased cell proliferation, suppressed Oct-4 expression and endothelial differentiation as well as in vitro vascular structure formation. In conclusion, ox-LDL promotes apoptosis and inhibits Oct-4 expression and self-renewal of MAPCs, and impairs their endothelial differentiation via suppression of Akt signalling. [ABSTRACT FROM AUTHOR]

Major earthquakes in the past indicated that pounding between bridge decks may result in significant structural damage or even girder unseating. With conventional expansion joints, it is impossible to completely avoid seismic pounding between bridge decks, because the gap size at expansion joints is usually not big enough in order to ensure smooth traffic flow. With a new development of modular expansion joint (MEJ), which allows a large joint movement and at the same time without impeding the smoothness of traffic flow, completely precluding pounding between adjacent bridge decks becomes possible. This paper investigates the minimum total gap that a MEJ must have to avoid pounding at the abutments and between bridge decks. The considered spatial ground excitations are modelled by a filtered Tajimi-Kanai power spectral density function and an empirical coherency loss function. Site amplification effect is included by a transfer function derived from the one-dimensional wave propagation theory. Stochastic response equations of the adjacent bridge decks are formulated. The effects of ground motion spatial variations, dynamic characteristics of the bridge and the depth and stiffness of local soil on the required separation distance are analysed. Soil-structure interaction effect is not included in this study. The bridge response behaviour is assumed to be linear elastic. Copyright © 2009 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Large-scale micro- and nano-sized Eu3+-doped gadolinium tungstate and molybdate Gd2MO6:Eu3+ (M=Mo, W) red phosphors with special morphologies have been successfully prepared via an efficient molten salt synthesis (MSS) method at 950°C for 6 h using NaCl and as the reaction medium. The results of X-ray powder diffraction patterns indicate that Gd2MoO6 and Gd2WO6 have monoclinic structures. The scanning electronic microscope and transmission electron microscope studies revealed that the samples of Gd2WO6:Eu3+ and Gd2MoO6:Eu3+ phosphors obtained by the MSS method in NaCl medium have a sphere-like morphology, and the corresponding samples obtained in KCl medium have rod-like morphologies. For the Gd2MoO6:Eu3+ phosphor obtained in NaCl and KCl media, the sphere-like particles had an average grain size of ∼100 nm, and the size of the rod-like particles ranged from 200 to 400 nm in length, and ∼150 nm in width, respectively. Compared with the same products obtained by the solid-state reaction we had reported, the luminescent properties of Gd2MO6:Eu3+ (M=Mo, W) are largely dependent on their morphology and crystal size prepared using different fluxes of NaCl and KCl. The reaction time and temperature also play an important role in the crystallization of the samples. [ABSTRACT FROM AUTHOR]

The article presents a research which examined the turbulent characteristics of the shallow rain-impacted water flow using a two-dimensional fibre-optic laser Doppler velocimetry (FLDV) and an artificial rainfall simulator. It states that raindrop and overland flow are factors affecting soil detachment and particle transportation. Under the study, the fluctuating turbulent shear stress was determined utilizing digital data processing procedures. Results revealed that the Reynolds shear stress depicts a probability distribution with heavy tails.

This article discusses the use of an artificial neural network to simulate the profiles of turbulence intensities and mean velocity for steep open channel flows. The authors measured turbulent flow in a laboratory flume using a fibre-optic laser Doppler velocimeter. The simulation model based on the training data was constructed using the multi-layer functional link network (MFLN). According to the authors, the MFLN neural network can almost perfectly simulate the turbulence intensity and velocity profile.