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Myocardial infarction (MI) causes massive cell death due to restricted blood flow and oxygen deficiency. Rapid and sustained oxygen delivery following MI rescues cardiac cells and restores cardiac function. However, current oxygen-generating materials cannot be administered during acute MI stage without direct injection or suturing methods, both of which risk rupturing weakened heart tissue. Here, we present infarcted heart-targeting, oxygen-releasing nanoparticles capable of being delivered by intravenous injection at acute MI stage, and specifically accumulating in the infarcted heart. The nanoparticles can also be delivered before MI, then gather at the injured area after MI. We demonstrate that the nanoparticles, delivered either pre-MI or post-MI, enhance cardiac cell survival, stimulate angiogenesis, and suppress fibrosis without inducing substantial inflammation and reactive oxygen species overproduction. Our findings demonstrate that oxygen-delivering nanoparticles can provide a nonpharmacological solution to rescue the infarcted heart during acute MI and preserve heart function.

The Sichuan-Yunnan area is located on the southeastern margin of the Tibet Plateau, and it interacts with the Tibet Plateau because of the the southeastward motion of the plateau material since the Cenozoic. Therefore, the Sichuan-Yunnan area acts an important window to understand the uplift and deformation processes of the largest and highest plateau in the world. In this study, we invert the teleseismic relative traveltime differentials extracted from waveform cross-correction to invert the P-wave and radial anisotropy (RAN) beneath the Sichuan-Yunnan area. In the tomographic inversion, we utilize an eikonal equation-based tomography method, and obtain the subsurface P-wave velocity and radial anisotropic structure down to a depth of 700 km. Our P-wave tomography results show that high-velocity anomalies are beneath Sichuan basin at depths from ~ 30 km to ~ 200 km, and remarkable low-velocity anomalies south of Sichuan basin are below the Xiaojiang fault and Red River fault at the same depths. Notably, low-velocity anomalies west of Sichuan basin are under the Songpan-Ganzi block at depths less than 200 km. In addition, our tomography results do not reveal high-velocity anomalies in the mantle transition zone (MTZ) beneath Xiaojiang fault. Evidently, the lithosphere of Sichuan basin exhibits negative radial anisotropy, and the Emeishan large igneous province shows visible negative radial anisotropy. Remarkably, positive radial anisotropy is found underneath Red River fault and it extends a depth of at least 170 km.

TiO2-red phosphorus/C nanofibers (TiO2-RP/CN) have been synthesized via electrospinning and then annealed with red phosphorus sublimation. Benefiting from the high electronic/ionic conductivity and robust stability of the unique structure, the TiO2-RP/CN show high reversible capacities, as well as an outstanding cycling ability. In K half cells, the capacity decay of the TiO2-RP/CN electrode mainly occurs in the first few cycles, and at 0.05 A g−1 it delivers a high specific capacity of 257.8 mA h g−1 after 500 cycles. K full cells were fabricated; these are well-matched with PTCDA (perylene-3,4,9,10-tetracarboxylic dianhydride) and also exhibited a good electrochemical performance (62 mA h g−1 after 100 cycles). Therefore, the TiO2-RP/CN are potential anode materials for use in K-ion batteries.

Ultra-short, ultra-intense laser pulses can create extreme physical conditions for a wide range of applications in atomic and molecular physics, materials chemistry, and inertial-confinement fusion. However, laser-matter interactions can be accompanied by significant X-ray emission that introduces radiation risks to the nearby environment and personnel. It is usually to monitor the radiation dose during in high-intensity laser-target interactions with optically stimulated luminescence and thermo-luminescence devices. However, these passive methods cannot measure the radiation dose in real time, while most active dosimeters cannot accurately measure pulsed radiation doses. Here, transient pulse X-ray radiation doses are converted by CdWO4 crystals into slow signals. Because the crystals have a 14-μs luminescence decay time, they can absorb sub-nanosecond X-ray pulses and release the energy at a 100-μs rate, thus reducing the linear-response pressure of subsequent devices. A pulse detector based on a CdWO4 crystal, a phototube, and a custom signal-processing circuit was developed. Experiments were performed at the 45-TW femtosecond laser facility of the Laser Fusion Research Center. The detector deviation was less than ±20% relative to that of an ionization-chamber detector. This initially verified its feasibility for real-time pulsed X-ray radiation detection.

BackgroundThe COVID-19 pandemic has drastically impacted many aspects of society and has indirectly produced various psychological consequences. This systematic review aimed to estimate the worldwide prevalence of posttraumatic stress disorder (PTSD) in children due to the COVID-19 pandemic, as well as to identify protective or risk factors contributing to child PTSD.MethodsWe conducted a systematic literature search in the PubMed, ProQuest, PsycINFO, Embase, Web of Science, WanFang, CNKI, and VIP databases. We searched for studies published between January 1, 2020 and May 26, 2021, that reported the prevalence of child PTSD due to the COVID-19 pandemic, as well as factors contributing to child PTSD. Eighteen studies were included in our systematic review, of which 10 studies were included in the meta-analysis.ResultsThe estimated prevalence of child PTSD after the COVID-19 outbreak was 28.15% (95% CI: 19.46–36.84%, I2 = 99.7%). In subgroup analyses for specific regions the estimated prevalence of post-pandemic child PTSD was 19.61% (95% CI: 11.23–27.98%) in China, 50.8% (95% CI: 34.12–67.49%) in the USA, and 50.08% in Italy (95% CI: 47.32–52.84%).ConclusionsFactors contributing to child PTSD were categorized into four aspects: personal factors, family factors, social factors and infectious diseases related factors. Based on this, we presented a new framework summarizing the occurrence and influence of the COVID-19 related child PTSD, which may contribute to a better understanding, prevention and development of interventions for child PTSD in forthcoming pandemics.

There are only a handful of reports on indium sulfide (In2S3) in the electrochemical energy storage field without a clear electrochemical reaction mechanism. In this work, a simple electrospinning method has been used to synthesize In2S3/C nanofibers for the first time. In lithium-ion batteries (LIBs), the In2S3/C nanofiber electrode can not only deliver a high initial reversible specific capacity of 696.4 mA h g−1 at 50 mA g−1, but also shows ultra-long cycle life with a capacity retention of 80.5% after 600 cycles at 1000 mA g−1. In sodium-ion batteries (SIBs), the In2S3/C nanofibers electrode can exhibit a high initial reversible specific capacity (393.7 mA h g−1 at 50 mA g−1) and excellent cycling performance with a high capacity retention of 97.3% after 300 cycles at 1000 mA g−1. The excellent electrochemical properties mainly benefited from In2S3 being encapsulated by a carbon matrix, which buffers the volume expansion and significantly improves the conductivity of the composite. Furthermore, the structural evolution of In2S3 during the first lithiation/delithiation and sodiation/desodiation processes has been illustrated by ex situ XRD. The results confirm that the reaction mechanism of In2S3 in both LIBs and SIBs can be summarized as conversion reactions and alloying reactions, which provide theoretical support for the development of In2S3 in the field of electrochemistry.

Ta-doped TiO2/C nanofibers are synthesized by an electrospinning method. First-principles calculations reveal that the Ta dopant can lower the Li/K diffusion barrier, which is beneficial for improving the rate capability. According to the electronic structure analysis, the dopant can obviously shift the conduction band of TiO2 downward, resulting in significantly improved electronic conductivity. Ta doping causes phase transformation from anatase to rutile, and increases the specific surface area. The well-designed rutile Ta-doped TiO2/C nanofibers show outstanding electrochemical properties in both Li-metal half cells and K-metal half cells, which are much better than those of pristine anatase TiO2/C nanofibers. At 2 A g−1, 5% rutile Ta-doped TiO2/C nanofibers could deliver high reversible specific capacities of 399 mA h g−1 in Li-ion batteries after 1000 cycles whereas deliver 148 mA h g−1 in K-ion batteries after 800 cycles. When assembled, the full cells with 5% rutile Ta-doped TiO2/C nanofibers as the anode and commercial LiFePO4/perylene-3,4,9,10-tetracarboxylic dianhydride as the cathode show excellent cycling performance and can light up more than 18 LEDs. These results demonstrate that Ta-doped TiO2/C nanofibers are a promising anode material for Li/K ion batteries.

Due to the uncertainty of wind power output, the congestion of wind power has become prominent. Exactly how to improve the capacity of wind power consumption has become a problem that needs to be studied urgently. In this paper, an energy storage system and energy-extensive load with adjustable characteristics are used as an important means of consuming wind power. Firstly, we analyze the reasons for the congestion according to the characteristics of wind power output, and establish a model of the grid’s ability to integrate wind power based on the concept of a wind power admissible interval. Secondly, we analyze the energy-extensive load regulation characteristics and establish an energy-extensive load dispatch model. Thirdly, on the basis of considering the energy-extensive load and energy storage system adjustment constraints, a bi-level optimization model is established. The upper level determines the configured capacity of the energy storage system with the goal of minimizing the total economic investment of the energy storage system, and the lower level coordinates the dispatching with the goal of maximizing wind power consumption and minimizing system operating costs. Finally, a certain region is taken as an example to verify the validity of the proposed method.

To save the transmission bandwidth of high-resolution (HR) images, we can send down-sampled low-resolution (LR) images and reconstruct them using super-resolution (SR) technology at the receiving end. However, image down-sampling by a large factor results in the loss of many spatial details. Instead, we use a combination of spatial down-sampling by a small factor and gray-level quantization to obtain the low hybrid-resolution images. Although the small down-sampling factor makes images retain more spatial details and real textures, the gray-level quantization introduces fake textures. Obviously, the real textures should be enhanced, and the fake textures should be eliminated. To address this issue, we propose a lightweight Adaptive Texture Distillation Network (ATDN) for image hybrid super-resolution. Our model uses the texture enhancement block (TEB) and the texture smoothing block (TSB) to handle real and fake textures in different ways. Considering that the mixing proportions of two kinds of textures in low hybrid-resolution images vary with regions, we specifically use a cascaded weight branch to adaptively adjust the weights of real and fake textures. Experiments reveal that our model can effectively deal with the mixing problem of real and fake textures, and our method can achieve superior performance to other lightweight methods.

Flexible electrode plays a key role in flexible energy storage devices. The SnTe/C nanofibers membrane (SnTe/CNFM) with excellent mechanical flexibility has been successfully synthesized for the first time through electrospinning, and it demonstrates outstanding electrochemical performance as free-standing anode for lithium/sodium-ion batteries. The SnTe/CNFM electrode delivers a discharge capacity of 526.7 mAh g−1 at 1000 mA g−1 after 1000 cycles in lithium-ion half-cells and a discharge capacity of 236.5 mAh g−1 at 500 mA g−1 after 80 cycles in lithium-ion full-cells with a LiFePO4 cathode. Not only that, it shows a discharge capacity of 182.7 mAh g−1 at 200 mA g−1 after 200 cycles in sodium-ion half-cells and a high discharge capacity of 207.0 mAh g−1 at 500 mA g−1 after 50 cycles in sodium-ion full-cells with a Na0.44MnO2 cathode. Moreover, the prepared SnTe/CNFM exhibits good mechanical flexibility. The SnTe/CNFM can still return to its original state without any breakage after bending, curling, folding and kneading. These results indicate that SnTe/CNFM is expected to become one of the promising free-standing anodes for lithium/sodium-ion batteries.

The spectrum of laser-plasma generated X-rays is very important, it characterizes electron dynamics in plasma and is basic for applications. However, the accuracies and efficiencies of existing methods to diagnose the spectrum of laser-plasma based X-ray pulse are not very high, especially in the range of several hundred keV. In this study, a new method based on electron tracks detection to measure the spectrum of laser-plasma produced X-ray pulses is proposed and demonstrated. Laser-plasma generated X-rays are scattered in a multi-pixel silicon tracker. Energies and scattering directions of Compton electrons can be extracted from the response of the detector, and then the spectrum of X-rays can be reconstructed. Simulations indicate that the energy resolution of this method is approximately 20% for X-rays from 200 to 550 keV for a silicon-on-insulator pixel detector with 12 $\rm \mu$m pixel pitch and 500 $\rm \mu$m depletion region thickness. The results of a proof-of-principle experiment based on a Timepix3 detector are also shown., Comment: final manuscript, 30 pages, 17 figures, published on NIM-A

Highlights The unique wire-in-wire structure endows TiO2/C nanofibers film with superior mechanical flexibility.The wire-in-wire TiO2/C nanofibers (TiO2 ww/CN) film shows outstanding electrochemical performances as free-standing anodes for Li/K-ion batteries and full cells.The TiO2 ww/CN film shows an extremely high pseudocapacitance contribution ratio in K-ion batteries. Supplementary Information The online version contains supplementary material available at 10.1007/s40820-021-00632-4., Wearable and portable mobile phones play a critical role in the market, and one of the key technologies is the flexible electrode with high specific capacity and excellent mechanical flexibility. Herein, a wire-in-wire TiO2/C nanofibers (TiO2 ww/CN) film is synthesized via electrospinning with selenium as a structural inducer. The interconnected carbon network and unique wire-in-wire nanostructure cannot only improve electronic conductivity and induce effective charge transports, but also bring a superior mechanic flexibility. Ultimately, TiO2 ww/CN film shows outstanding electrochemical performance as free-standing electrodes in Li/K ion batteries. It shows a discharge capacity as high as 303 mAh g−1 at 5 A g−1 after 6000 cycles in Li half-cells, and the unique structure is well-reserved after long-term cycling. Moreover, even TiO2 has a large diffusion barrier of K+, TiO2 ww/CN film demonstrates excellent performance (259 mAh g−1 at 0.05 A g−1 after 1000 cycles) in K half-cells owing to extraordinary pseudocapacitive contribution. The Li/K full cells consisted of TiO2 ww/CN film anode and LiFePO4/Perylene-3,4,9,10-tetracarboxylic dianhydride cathode possess outstanding cycling stability and demonstrate practical application from lighting at least 19 LEDs. It is, therefore, expected that this material will find broad applications in portable and wearable Li/K-ion batteries. Supplementary Information The online version contains supplementary material available at 10.1007/s40820-021-00632-4.

The Gamma-Ray Integrated Detectors (GRID) is a space mission concept dedicated to monitoring the transient gamma-ray sky in the energy range from 10 keV to 2 MeV using scintillation detectors onboard CubeSats in low Earth orbits. The primary targets of GRID are the gamma-ray bursts (GRBs) in the local universe. The scientific goal of GRID is, in synergy with ground-based gravitational wave (GW) detectors such as LIGO and VIRGO, to accumulate a sample of GRBs associated with the merger of two compact stars and study jets and related physics of those objects. It also involves observing and studying other gamma-ray transients such as long GRBs, soft gamma-ray repeaters, terrestrial gamma-ray flashes, and solar flares. With multiple CubeSats in various orbits, GRID is unaffected by the Earth occultation and serves as a full-time and all-sky monitor. Assuming a horizon of 200 Mpc for ground-based GW detectors, we expect to see a few associated GW-GRB events per year. With about 10 CubeSats in operation, GRID is capable of localizing a faint GRB like 170817A with a 90% error radius of about 10 degrees, through triangulation and flux modulation. GRID is proposed and developed by students, with considerable contribution from undergraduate students, and will remain operated as a student project in the future. The current GRID collaboration involves more than 20 institutes and keeps growing. On August 29th, the first GRID detector onboard a CubeSat was launched into a Sun-synchronous orbit and is currently under test., accepted for publication in Experimental Astronomy

New oxygen and pressure sensitive paints (PSPs) with four-arm polymeric structures were prepared by using a kind of controlled living polymerizations – atom transfer radical polymerization (ATRP). The polymers composing of poly(isobutyl methacrylate)-co-poly(trifluoroethyl methacrylate)s (PolyIBMA-co-PolyTFEM)s act as the matrices for the platinum porphyrin-based phosphorescence probes, which were copolymerized in the matrices. The polymers were characterized by using 1H NMR, 19F NMR, and GPC to demonstrate their successful preparation. The influence of polymer structures on sensing activity including the sensitivity and response time to oxygen and/or pressure was investigated. Results showed that copolymers with suitable compositions (herein P3) can have highest sensitivity. Polymer structure’s influence on response time to oxygen was also investigated. For increasing the polymer’s surface area for further improving sensing sensitivity, electrospinning method was used for preparing films with micro-spherical or fibrous structures. The morphologies of electrospinning coated films were observed by SEM. Results showed that electrospinning coated films can respond much better to oxygen and pressure than their corresponding sprayed plates. This is the first time to apply the controlled living polymerization approach to prepare PSPs with multi-arm structures, which will broaden the PSP functional materials’ design strategy.

Polymeric microfibers, particularly the fluorinated copolymers’ fibers, are promising functional materials for photoelectric devices, sensing, and energy storage due to their various surface characteristics. However, to obtain the high fluorine content copolymer-based fibers with considerable uniformity is likely to be especially challenging, which seriously debilitates their applications in sensor devices. Herein, for the first time, we presented a high fluorine content platinum porphyrin-grafted poly(isobutyl methacrylate-co-dodecafluoroheptyl methacrylate) copolymers (PtTFPP-p(IBM-co-DFHMA)) microfibrous thin-films used as optical oxygen sensors. The porous thin-film frameworks were formed of uniform microfibers, which afforded an exceptional improvement in sensitivity and exhibited 584% higher sensitivity than the solid sensing film owing to the large specific surface area, porous structures and oxygen diffusion enhancement by fluorine elements. Additionally, the remarkable emission intensity-changing characteristic of the microfiber sensing film under various air pressures facilitates convenient visualization of pressure distributions on film surface. The characteristics are particularly important for the computational fluid dynamics simulations in various sensing fields such as unsteady flow visualization and unsteady pressure measurements, etc. Owing to its attractive advantages and versatile performance, fluorine-containing copolymers fibers are expected to provide a new strategy for the rational design of high performance gas sensor devices.

The Chinese CubeSat Mission, Gamma Ray Integrated Detectors (GRID), recently detected its first gamma-ray burst, GRB 210121A, which was jointly observed by the Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM). This burst is confirmed by several other missions, including \fermi and \textit{Insight}-HXMT. We combined multi-mission observational data and performed a comprehensive analysis of the burst's temporal and spectral properties. Our results show that the burst is relatively special in its high peak energy, thermal-like low energy indices, and large fluence. By putting it to the $E_{\rm p}$-$E_{\rm\gamma, iso}$ relation diagram with assumed distance, we found this burst can be constrained at the redshift range of [0.3,3.0]. The thermal spectral component is also confirmed by the direct fit of the physical models to the observed spectra. Interestingly, the physical photosphere model also constrained a redshift of $z\sim$ 0.3 for this burst, which help us to identify a host galaxy candidate at such a distance within the location error box. Assuming the host galaxy is real, we found the burst can be best explained by the photosphere emission of a typical fireball with an initial radius of $r_0\sim$ 3.2 $\times 10^7$ cm., Comment: ApJ accpeted; 12 pages, 11 figures, 3 tables

There are only a handful of reports on indium sulfide (In2S3) in the electrochemical energy storage field without a clear electrochemical reaction mechanism. In this work, a simple electrospinning method has been used to synthesize In2S3/C nanofibers for the first time. In lithium-ion batteries (LIBs), the In2S3/C nanofiber electrode can not only deliver a high initial reversible specific capacity of 696.4 mA h g-1 at 50 mA g-1, but also shows ultra-long cycle life with a capacity retention of 80.5% after 600 cycles at 1000 mA g-1. In sodium-ion batteries (SIBs), the In2S3/C nanofibers electrode can exhibit a high initial reversible specific capacity (393.7 mA h g-1 at 50 mA g-1) and excellent cycling performance with a high capacity retention of 97.3% after 300 cycles at 1000 mA g-1. The excellent electrochemical properties mainly benefited from In2S3 being encapsulated by a carbon matrix, which buffers the volume expansion and significantly improves the conductivity of the composite. Furthermore, the structural evolution of In2S3 during the first lithiation/delithiation and sodiation/desodiation processes has been illustrated by ex situ XRD. The results confirm that the reaction mechanism of In2S3 in both LIBs and SIBs can be summarized as conversion reactions and alloying reactions, which provide theoretical support for the development of In2S3 in the field of electrochemistry.

The hybrid pixel detector Timepix3 allows the measurement of the time and energy deposition of an event simultaneously in each 55 $\mu$m pixel, which makes Timepix3 a promising approach for a compact Compton camera. However, the angular resolution of Compton camera based on this kind of detector with high pixel density is usually degraded in imaging of MeV gamma-ray sources, because the diffusion of energetic Compton electron or photoelectron could trigger many pixels and lead to an inaccurate measurement of interaction position. In this study, an electron track algorithm is used to reconstruct the electron track and determine the interaction point. An demonstrative experiment was carried out, showing that the effect of this algorithm was significant. The angular resolution measures of a single layer Compton camera based on Timepix3 was enhanced to 12 degrees (FWHM) in imaging of a Co-60 gamma source., Comment: final manuscript, 27 pages, 13 figures, published on NIM-A

Three four-arm amphiphilic block copolymers with different chain lengths, consisting of a hydrophilic chain of polyethylene glycol (PEG) and hydrophobic segment of polycaprolactam (PCL), were synthesized and used to encapsulate the high-efficient and hydrophobic oxygen probe of platinum(II)-5,10,15,20-tetrakis-(2,3,4,5,6-pentafluorophenyl)-porphyrin (PtTFPP) to form polymer micelles. This approach enabled the use of PtTFPP in aqueous solution for biosensing. Experimental results demonstrated that the particle sizes of these nano-oxygen sensors between 40.0 and 203.8 nm depend on the structures of block copolymers. PtTFPP in these micelles showed an effective quantum yield under nitrogen environment, ranging from 0.06 to 0.159. The new sensors are suitable for analyzing dissolved oxygen concentrations in the range of 0.04&ndash, 39.3 mg/L by using the linear Stern&ndash, Volmer equation at room temperature. In addition, it has been shown that these sensors are capable of in situ monitoring the dissolved oxygens in the culture medium of E. coli and Romas cells during the respiration process, and distinguishing the drug activity of antibiotic ampicillin from that of antimycin A. This study showed that the use of these nanostructured multi-arm block copolymer micelles can achieve efficient biological applications without specific structural modification of the hydrophobic PtTFPP probe, which is expected to have broad prospects.

The excellent electrochemical performance of indium sulfide (In2S3) in lithium ion batteries (LIBs) and sodium ion batteries (SIBs) prompted us to explore its energy storage mechanism in potassium ion batteries (PIBs). In this work, In2S3/C nanofibers are successfully synthesized by simple electrospinning and subsequent vulcanization. In K half cells, compared to commercial In2S3 electrodes, In2S3/C nanofibers as anode materials for PIBs show outstanding electrochemical performance, which can deliver reversible capacities of 397.6 (25), 366.2 (50), 335.2 (100), 307.8 (200), 260.4 (500) and 212.2 mAh g−1 (1000 mA g−1), respectively. In K full cells, In2S3/C nanofibers can also show good potassium storage performance and can light up 15 light emitting diodes (LEDs). The superb electrochemical performance of In2S3/C nanofibers is due to the in-situ composite with self-nitrogen-doped carbon matrix and the nanoization of In2S3 particles, which buffers the volume effect and improves the conductivity of the material during the potassium storage process. In addition, the mechanism of potassium storage of In2S3/C nanofibers was systematically studied by cyclic voltammetry (CV), ex-situ XRD, TEM and XPS methods. The mechanism of In2S3 for K-ion storage can be described as the conversion reaction: In2S3 + 6K+ + 6e− ⇌ In + 3K2S.

Both antimony selenide and antimony are promising anode materials for lithium-ion batteries. However, owing to the influence of the poor electronic conductivity of Sb2Se3 and the large volume expansion of the two materials during the lithiation process, their electrochemical performance is limited and the practical application is restricted. In this work, for the first time, the hierarchical Sb2Se3 and Sb particles fully encapsulated into carbon nanofibers (Sb2Se3/Sb/C nanofibers) have been in-situ synthesized by electrospinning followed by controlled annealing. Combining the advantages of high specific capacity of Sb2Se3, good electronic conductivities of Sb and C, and strong stability of C matrix, the Sb2Se3/Sb/C nanofibers electrode shows excellent lithium-storage performance. It achieves a high reversible capacity (764 mA h g−1 after 300 cycles at 0.1 A g−1), splendid ultralong cycling stability (429 mA h g−1 after 1000 cycles at 1 A g−1), and high rate capability (342 mA h g−1 at 5 A g−1). It demonstrates that Sb2Se3/Sb/C nanofibers are promising high-performance anode materials for lithium-ion batteries.

The key to the development of wearable electronic equipment lies in the design of flexible batteries, in which the electrodes with outstanding mechanical behavior are quite important. Herein, porous nitrogen-doped Sn/C fibers (P-Sn/C-N Fs) film has been successfully synthesized via simple electrospinning and subsequent calcination process in which folic acid and polymethylmethacrylate (PMMA) play the role of introducing nitrogen and forming pores, respectively. The introduction of nitrogen improves the electronic conductivity of the material, and the presence of porous structure increases the specific surface area. More importantly, when the P-Sn/C-N Fs film is used directly as a free-standing electrode for lithium ion batteries, it exhibits outstanding electrochemical performance. The P-Sn/C-N Fs film exhibits a discharge capacity of 712.1 mAh g−1 at 500 mA g−1 after 500 cycles. Even at the high current density of 5 A g−1, it displays a high discharge capacity of 429.1 mAh g−1 after 1000 cycles. These findings indicate that the P-Sn/C-N Fs film has the potential to be applied as free-standing anode materials for lithium ion batteries.

Monitoring extracellular pH (pHe) is important for biology understanding, since pHe and its homeostasis are closely relevant to cellular metabolism. Hydrogel-based pHe sensors have attracted significant attention and showed wide application, while they are tedious with significant time-cost operation and reproducibility variations for high-throughput application. Herein, we synthesized two polymers for pHe monitoring which are soluble in water at room temperature with easy operations and high reproducibility among various micro-plate wells for high-throughput analysis. P1 (P(OEGMA-co-MEO2MA-co-pHS)) and P2 (P(OEGMA-co-pHS)) were synthesized via the Reversible Addition Fragmentation Chain Transfer (RAFT) copolymerization of oligo(ethylene glycol) methacrylate (OEGMA), 2-(2′-methoxyethoxy) ethyl methacrylate (MEO2MA) and the pH sensitive fluorescence moiety N-fluoresceinyl methacrylamide (pHS). P1 is soluble in water at room temperature (25 °C) while insoluble at the temperature above 33 °C, indicating its feature of lower critical solution temperature (LCST) at 33 °C. Further P1 showed higher pH sensitivity and photostability than P2 (without LCST property) when used at physiological temperature (37 °C). Thus, P1 was chosen to in-situ monitor the micro-environmental acidification of E. coli, Hela and Ramos cells during their growth, and the metabolism inhibiting activity of a representative antibiotic, ampicillin. Cell concentration-dependent cellular acidification and drug concentration-dependent inhibition of cellular acidification were observed, demonstrating that the LCST polymer (P1) is suitable for real-time cellular acidification monitoring as well as for high-throughput drug screening. This study firstly demonstrated the use of a LCST polymeric sensor for high-throughput screening of antibiotics and investigation of cell metabolism.

New amphiphilic star or multi-arm block copolymers with different structures were synthesized for enabling the use of hydrophobic oxygen probe of platinum (II)-tetrakis (pentafluorophenyl) porphyrin (PtTFPP) for bioanalysis. The amphiphilic star polymers were prepared through the Atom Transfer Radical Polymerization (ATRP) method by using hydrophilic 4-arm polyethylene glycol (4-arm-PEG) as an initiator. Among the five block copolymers, P1 series (P1a, P1b, and P1c) and P3 possess fluorine-containing moieties to improve the oxygen sensitivity with its excellent capacity to dissolve and carry oxygen. A polymer P2 without fluorine units was also synthesized for comparison. The structure-property relationship was investigated. Under nitrogen atmosphere, high quantum efficiency of PtTFPP in fluorine-containing micelles could reach to 22% and long lifetime could reach to 76 μs. One kind of representative PtTFPP-containing micelles was used to detect the respiration of Escherichia coli (E. coli) JM109 and macrophage cell J774A.1 by a high throughput plate reader. In vivo hypoxic imaging of tumor-bearing mice was also achieved successfully. This study demonstrated that using well-designed fluoropolymers to load PtTFPP could achieve high oxygen sensing properties, and long lifetime, showing the great capability for further in vivo sensing and imaging.

Tungsten oxide thin films were deposited at room temperature under different negative bias voltages (Vb, 0 to −500 V) by DC reactive magnetron sputtering, and then the as-deposited films were annealed at 500 °C in air atmosphere. The crystal structure, surface morphology, chemical composition and transmittance of the tungsten oxide thin films were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and UV–vis spectrophotometer. The XRD analysis reveals that the tungsten oxide films deposited at different negative bias voltages present a partly crystallized amorphous structure. All the films transfer from amorphous to crystalline (monoclinic + hexagonal) after annealing 3 h at 500 °C. Furthermore, the crystallized tungsten oxide films show different preferred orientation. The morphology of the tungsten oxide films deposited at different negative bias voltages is consisted of fine nanoscale grains. The grains grow up and conjunct with each other after annealing. The tungsten oxide films deposited at higher negative bias voltages after annealing show non-uniform special morphology. Substoichiometric tungsten oxide films were formed as evidenced by XPS spectra of W4f and O1s. As a result, semi-transparent films were obtained in the visible range for all films deposited at different negative bias voltages.

Phase transformation of TiO2 powder (P25) and pure anatase (PA) was investigated under pure oxygen as well as vacuum from 500 to 1,000 °C. The rutile percentage calculated based on the XRD data was used to estimate the phase transformation process. It was found that the vacuum suppressed the phase transformation of P25 relative to pure oxygen atmosphere. A model was proposed to explain the effect of oxygen on the phase transformation of TiO2. Furthermore, P25 samples showed lower phase transformation temperature (between 600 and 800 °C) compared with PA (over 1,000 °C). The existed rutile phase in P25 was regarded as a transformation inducer due to an interface between anatase and rutile phases since the nucleation activation energy on the interface is lower than that on the surface. And this interface effect is also adopted to explain the role of additive WO3, which retarded the phase transformation of P25 but promoted the phase transformation of PA.

With the development of urban rail transit line networking, precisely obtaining the travel time distribution and analyzing its characters have become very important. This paper is based on Automated Fare Card data to obtain the travel time distributions by analyzing the transaction records from Automated Fare Collection system. Beijing Metro is used as a case study. By choosing typical Origins to Destinations with different travel distances and transfer times, travel time distributions are generated and get fitted to the curves. A linear model is used to describe the travel time with different distance and transfer times. With consideration of the actual travel distance, transfer times, the time period and some other factors, a travel time prediction method is proposed. This proposed measure is used to predict the travel time from the time point when passengers swipe their smartcards at the entry gate to the time point when they reach the exit gate. The outcomes of this research are validated by the actual OD data from the Beijing Metro case.