Abstract ：

Direct chemiluminescence (CL) of fluorescent gold nanoclusters was observed for the first time upon oxidation with classic oxidants. The CL mechanism was investigated by the studies of CL spectrum, UV-vis absorption spectra and X-ray photoelectron spectra before and after the reaction. The excited state Mn(II)*, originating from the reduction of permanganate with gold nanoclusters, was suggested as the possible luminophor for the reaction. The potential analytical application was demonstrated by using hydrogen peroxide as an example, based upon the fact that hydrogen peroxide decreased the CL signal significantly. The decreased CL intensity was proportional to the concentration of hydrogen peroxide in the range 1.0×10-6-1.0×10-4molL-1. The detection limit was 5×10-7molL-1and the relative standard deviation was 1.4% for 1.0×10-5molL-1hydrogen peroxide in 11 replicated measurements. This method was applied to the determination of hydrogen peroxide in water samples with satisfactory results. © 2015 The Authors.

Keyword ：

Acidic permanganate Analytical applications Gold nanocluster Hydrogen peroxide sensing Relative standard deviations Replicated measurements UV-VIS absorption spectra X ray photoelectron spectra

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An accurate intracranial pressure (ICP) measurement is vital for patients with hydrocephalus. ICP is generally measured by lumbar puncture opening pressure, which is invasive and has potential adverse side effects. Intraocular pressure (IOP) was investigated to measure ICP indirectly; however, its accuracy was controversial. We conducted this retrospective study to investigate whether IOP can be used as a surrogate for ICP in hydrocephalus patients.We performed a retrospective study enrolled 50 cases, including 32 patients with normal pressure hydrocephalus (NPH) and 18 patients with high pressure hydrocephalus (HPH). The independent factors of ICP, the correlation between ICP and other factors, and diagnostic value of IOP and papilledema to predict ICP were analysed, respectively.Patients with HPH were more likely suffered from visual deterioration (33.33% vs. 9.38%, p = .045) and papilledema (55.56% vs. 3.13%, p = .001). Multivariate analysis revealed that papilledema was a significant factor (OR =40.765, 95%CI 3.331-498.846, p = .004). Pearson's correlation analysis indicated that ICP did not correlate with any other factors.IOP was not an independent factor of ICP in patients with hydrocephalus, and could not be used to determine IOP. Papilledema might be a significant factor of ICP in hydrocephalus sufferers. Compared with NPH patients, patients with HPH were more prone to develop papilledema.

Keyword ：

intracranial pressure intraocular pressure age Hydrocephalus papilledema

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Accurate calculation of the transient cooling performance is crucial for the operation and control of a reverse Brayton refrigerator. Components of the refrigerator have complex working characteristics individually and interact each other mutually. To solve the problem easily, the turboexpander matching characteristics were usually ignored and relations among components were simplified. In this study, a cryogenic reverse Brayton air refrigerator equipped with gas bearing turboexpander and plate-fin heat regenerator was presented. The ultimate refrigerating temperature was proposed through analysis. The transient cooling characteristics of the cryogenic part in refrigerator were resolved into the turboexpander matching performance and the regenerator transient cooling characteristics. The regenerator was simulated through numerical heat transfer and computational fluid dynamics by considering the axial conduction and cold loss. The matching model was improved by adopting a significant method of constant rotating speed. Using the dual non-steady time steps, a transient cooling model of the cryogenic part was explored via C++ code, and verified by experiment. Through the model, the refrigerator cooling performances were evaluated under different operation modes, and the energy utilization efficiency was determined. It can be used to evaluate the operation strategy of refrigerators and help to promote energy efficiency. © 2018 Elsevier Ltd

Keyword ：

Brayton Dynamic matching Energy utilization efficiency Numerical heat transfer Operation and control Operational performance Transient cooling Ultimate refrigerating temperatures

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Heat recovery is one of the solutions to reduce Carbon dioxide emission, and using latent heat thermal energy storage systems (LHTESS) can be a promising way for heat recovery. In the present article, for the first time, the effects of both inorganic nanoparticles as an additive to PCM (phase change materials) and magnetic field on the PCM solidification rate inside a porous energy storage system have been modeled. For this purpose, the mixture of CuO nanoparticles and water was used as NEPCM (nanoparticle-enhanced PCM), and an external magnetic field was applied to the system. The unsteady process of solidification inside the storage system was simulated by employing finite element method (FEM). The impacts of various parameters including Lorentz forces strength, CuO/water concentration, and Rayleigh number on the charging time have been evaluated. Solid fraction, temperature, and streamline contours have been plotted to study the solidification process locally. The results indicated that with augmenting the Hartmann number from 0 to 10, the solidification time was reduced up to 23.5% in average. On the other hand, the addition of nanoparticles to PCM with volume fractions up to 4% leads to, on average, a 14% decrease in the solidification time. The obtained results suggest to employ the magnetic field as an effective solution to accelerate the solidification in energy storage systems while to reinforce the influence of magnetic field; nanoparticles can be added to the PCM. Finally, the solidification time was correlated with three main design parameters, i.e. nanoparticle volume fraction, Hartmann and Rayleigh numbers with a mathematical expression. (C) 2019 Elsevier Ltd. All rights reserved.

Keyword ：

NEPCM Porous media Thermal energy storage Magnetic field Solidification

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IEEE Recent research has proposed a moving target defense (MTD) approach that actively changes transmission line susceptance to preclude stealthy false data injection (FDI) attacks against the state estimation of a smart grid. However, existing studies were often conducted under a weak adversarial setting, in that they ignore the possibility that alert attackers can also try to detect the activation of MTD before they launch the FDI attacks. We call this new threat as Parameter Confirming-First (PCF) FDI. To improve the stealthiness of MTD, we propose a hidden MTD approach that cannot be detected by the attackers and prove its equivalence to an MTD that maintains the power flows of the whole grid. Moreover, we analyze the completeness of MTD and show that any hidden MTD is incomplete in that FDI attacks may bypass the hidden MTD opportunistically. This result suggests that the stealthiness and completeness are two conflicting goals in MTD design. Finally, we propose an approach to enhancing the hidden MTD against a class of highly structured FDI attacks. We also discuss the MTD’s operational costs under the dc and ac models. We conduct simulations to show the effectiveness of the hidden MTD against PCF-FDI attacks under realistic settings.

Keyword ：

Computer security False data injection attack moving target defense Power measurement smart grid Smart grids State estimation state estimation.

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Stimuli-responsive bio-based polymeric systems are gaining considerable attention as intelligent versatile tools that show great potential in various fields. In this review, an overview is given of recent developments of stimuli-responsive bio-based polymeric systems. The characteristics of bio-based polymers in different applications are discussed and the superiority of these advanced stimuli-responsive bio-based polymeric systems is highlighted. Furthermore, several emerging applications of these systems including intelligent drug delivery, responsive food packaging and smart water treatment are discussed and the section of intelligent drug delivery is emphasized in detail. Finally, the respective prospects and limitations inherent to these systems are addressed.

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Injectable hydrogels with multifunctional properties, including tissue adhesiveness and pH-sensitivity are highly desired for localized drug delivery in disease treatment, and their design is still challenging. We developed a series of multifunctional injectable mucoadhesive and pH-responsive hydrogels based on chitosan-grafted-dihydrocaffeic acid (CS-DA) and oxidized pullulan (OP) via a Schiff base reaction. These hydrogels exhibited good injectability, suitable gelation time, in vitro pH-dependent equilibrated swelling ratios, morphologies, and rheological characteristics. The desirable in vitro pH-sensitive drug release behavior of these hydrogels was demonstrated by a drug release test with anti-cancer drug doxorubicin (DOX) loaded hydrogels at different pH values. The hydrogels showed good DOX release, effectively killing colon tumor cells (HCT116 cells) and good antibacterial properties against E. coli and S. aureus in vitro when the antibacterial model drug amoxicillin was encapsulated in the hydrogels. A lap-shear test was also carried out with these hydrogels. The hydrogels exhibited good mucosal adhesion, indicating their potential use in mucosa-localized drug delivery systems. All these results suggest that these injectable pH-responsive adhesive hydrogels are ideal candidates for development of colon cancer drug delivery carriers or mucoadhesive drug delivery systems.

Keyword ：

Injectable hydrogel pH-responsive Drug delivery carriers Chitosan Mucoadhesion

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An efficient transition-metal free C-C bond cleavage/borylation of cycloketone oxime esters has been described. In this reaction, the B2(OH)4 reagent not only served as the boron source but also acted as an electron donor source through formation of a complex with a DMAc-like Lewis base. This complex could be used as an efficient single electron reductant in other ring-opening transformations of cycloketone oxime esters. Free-radical trapping, radical-clock, and DFT calculations all suggest a radical pathway for this transformation. © The Royal Society of Chemistry.

Keyword ：

C-c bond cleavages DFT calculation Electron donors Radical clocks Radical pathway Radical trapping Ring opening Single electron

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© 2018 A calculation model is developed to investigate the pressurization performance and thermal stratification in a liquid hydrogen (LH2) tank. Viscous flow is considered in the stratification model to ensure the continuity of fluid flow and heat exchange. The tank pressure rise, energy distribution and thermal stratification are studied respectively. Compared to the results without considering the phase change, the tank pressure, the stratified layer temperature and the ullage temperature calculated with phase change considered, have increased about 69.98%, 70.90% and 15.53%. Moreover, influences of the gravity level, initial wall temperature and initial liquid height on the development of thermal stratification are analyzed. It turns out that the larger the gravity level is, the faster the liquid thermal stratification develops. The effect of the initial wall temperature on the growth of thermal stratification is the same. Both the ullage pressure and the stratified temperature increase with time. While the gravity level is larger than a certain value and the initial wall temperature is less than a certain value, the ullage pressure and the stratified temperature decrease firstly, and then increase. Meanwhile, it costs much more time for fluid thermal stratification development fully for a larger initial liquid height.

Keyword ：

Constant wall temperature Liquid hydrogen Pressure rise Thermal stratification

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Halide perovskites are promising semiconductors for inexpensive, high-performance optoelectronics. Despite a remarkable defect tolerance compared to conventional semiconductors, perovskite thin films still show substantial microscale heterogeneity in key properties such as luminescence efficiency and device performance. However, the origin of the variations remains a topic of debate, and a precise understanding is critical to the rational design of defect management strategies. Through a multi-scale investigation - combining correlative synchrotron scanning X-ray diffraction and time-resolved photoluminescence measurements on the same scan area - we reveal that lattice strain is directly associated with enhanced defect concentrations and non-radiative recombination. The strain patterns have a complex heterogeneity across multiple length scales. We propose that strain arises during the film growth and crystallization and provides a driving force for defect formation. Our work sheds new light on the presence and influence of structural defects in halide perovskites, revealing new pathways to manage defects and eliminate losses.

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