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"Tian, Cui"
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Combined technologies for the remediation of soils contaminated by organic pollutants. A review
Organic-contaminated soils are a major health issue because pollutants can be transferred to waters, air, and living organisms. Many remediation technologies have been developed, yet single methods are usually not fully efficient due to the wide diversity of soil and pollutant properties. Therefore, combining several methods has recently shown wider application range, higher efficiency, and better economic benefits. Here we compare combined remediation technologies to clean organic-contaminated soils, with focus on physical–chemical, physical–chemical-biological, and biological-microbial methods. Physical–chemical methods are the most widely used due to their high efficiency, yet they are costly, and they alter soil properties. These issues can be alleviated by adding a biological treatment. Combined biological-microbial methods are more recent and rely on bioengineering.
Journal Article
Electrons dynamics control by shaping femtosecond laser pulses in micro/nanofabrication: modeling, method, measurement and application
During femtosecond laser fabrication, photons are mainly absorbed by electrons, and the subsequent energy transfer from electrons to ions is of picosecond order. Hence, lattice motion is negligible within the femtosecond pulse duration, whereas femtosecond photon-electron interactions dominate the entire fabrication process. Therefore, femtosecond laser fabrication must be improved by controlling localized transient electron dynamics, which poses a challenge for measuring and controlling at the electron level during fabrication processes. Pump-probe spectroscopy presents a viable solution, which can be used to observe electron dynamics during a chemical reaction. In fact, femtosecond pulse durations are shorter than many physical/chemical characteristic times, which permits manipulating, adjusting, or interfering with electron dynamics. Hence, we proposed to control localized transient electron dynamics by temporally or spatially shaping femtosecond pulses, and further to modify localized transient materials properties, and then to adjust material phase change, and eventually to implement a novel fabrication method. This review covers our progresses over the past decade regarding electrons dynamics control (EDC) by shaping femtosecond laser pulses in micro/nanomanufacturing: (1) Theoretical models were developed to prove EDC feasibility and reveal its mechanisms; (2) on the basis of the theoretical predictions, many experiments are conducted to validate our EDC-based femtosecond laser fabrication method. Seven examples are reported, which proves that the proposed method can significantly improve fabrication precision, quality, throughput and repeatability and effectively control micro/nanoscale structures; (3) a multiscale measurement system was proposed and developed to study the fundamentals of EDC from the femtosecond scale to the nanosecond scale and to the millisecond scale; and (4) As an example of practical applications, our method was employed to fabricate some key structures in one of the 16 Chinese National S&T Major Projects, for which electron dynamics were measured using our multiscale measurement system.
Journal Article
Formation of twelve-fold iodine coordination at high pressure
Halogen compounds have been studied widely due to their unique hypercoordinated and hypervalent features. Generally, in halogen compounds, the maximal coordination number of halogens is smaller than eight. Here, based on the particle swarm optimization method and first-principles calculations, we report an exotically icosahedral cage-like hypercoordinated IN
6
compound composed of N
6
rings and an unusual iodine−nitrogen covalent bond network. To the best of our knowledge, this is the first halogen compound showing twelve-fold coordination of halogen. High pressure and the presence of N
6
rings reduce the energy level of the 5d orbitals of iodine, making them part of the valence orbital. Highly symmetrical covalent bonding networks contribute to the formation of twelve-fold iodine hypercoordination. Moreover, our theoretical analysis suggests that a halogen element with a lower atomic number has a weaker propensity for valence expansion in halogen nitrides.
High pressure can modify the chemical properties of the elements, giving rise to exotic bonding. Here the authors report the prediction of a nitrogen-rich iodine nitride compound IN
6
where the iodine atom has an unusual twelve-fold coordination, stable above 100 GPa.
Journal Article
Synthesis of molecular metallic barium superhydride: pseudocubic BaH12
Following the discovery of high-temperature superconductivity in the La–H system, we studied the formation of new chemical compounds in the barium-hydrogen system at pressures from 75 to 173 GPa. Using in situ generation of hydrogen from NH
3
BH
3
, we synthesized previously unknown superhydride BaH
12
with a pseudocubic (
fcc
) Ba sublattice in four independent experiments. Density functional theory calculations indicate close agreement between the theoretical and experimental equations of state. In addition, we identified previously known
P
6
/mmm
-BaH
2
and possibly BaH
10
and BaH
6
as impurities in the samples. Ab initio calculations show that newly discovered semimetallic BaH
12
contains H
2
and H
3
–
molecular units and detached H
12
chains which are formed as a result of a Peierls-type distortion of the cubic cage structure. Barium dodecahydride is a unique molecular hydride with metallic conductivity that demonstrates the superconducting transition around 20 K at 140 GPa.
Metallization of pure hydrogen via overlapping of electronic bands requires high pressure above 3 Mbar. Here the authors study the Ba-H system and discover a unique superhydride BaH
12
that contains molecular hydrogen, which demonstrates metallic properties and superconductivity below 1.5 Mbar.
Journal Article
Enhancement of superconducting properties in the La–Ce–H system at moderate pressures
Ternary hydrides are regarded as an important platform for exploring high-temperature superconductivity at relatively low pressures. Here, we successfully synthesized the
hcp
-(La,Ce)H
9-10
at 113 GPa with the initial La/Ce ratio close to 3:1. The high-temperature superconductivity was strikingly observed at 176 K and 100 GPa with the extrapolated upper critical field
H
c2
(0) reaching 235 T. We also studied the binary La-H system for comparison, which exhibited a
T
c
of 103 K at 78 GPa. The
T
c
and
H
c2
(0) of the La-Ce-H are respectively enhanced by over 80 K and 100 T with respect to the binary La-H and Ce-H components. The experimental results and theoretical calculations indicate that the formation of the solid solution contributes not only to enhanced stability but also to superior superconducting properties. These results show how better superconductors can be engineered in the new hydrides by large addition of alloy-forming elements.
Recently, high-temperature superconductivity has been reported in LaH
10
and CeH
10
. Here, the authors report superconductivity in the alloy (La,Ce)H
9-10
with
T
c
= 176 K at 100 GPa, providing an improved compromise between high transition temperature and low pressure requirements.
Journal Article
How Can China Resolve the NIMBY Dilemma in a Network Society? Government and Society-Negotiated Decisions Based on Evolutionary Game Analysis
Infrastructure, such as waste incineration infrastructure, is entangled in the “not in my back yard” (NIMBY) dilemma. Consequently, the closed public decision-making model has difficulty adapting to the increasingly strong public-participation needs. Thus, a new mode of negotiated decision making is urgently required. This paper focuses on the negotiation problem, considers the government and society as game players, builds an evolutionary game model of negotiated decisions based on the bounded rationality hypothesis, and simulates the process and results of the evolution of the players’ strategy. The study concludes that the stable state of system evolution depends on the initial state of the dual populations and the comparative relationship between changes in revenue and cost, and the sufficient and unnecessary condition for the government and society to both agree on the given strategy. Taking the waste incineration projects in Yuhang and Chaonan as examples, the negotiated decision-making practice of NIMBY facilities is analysed, and it is found that it takes less time for the system to reach equilibrium in the latter. Finally, optimisation strategies for decision making regarding NIMBY facilities are systematically proposed.
Journal Article
Wearable Continuous Blood Pressure Monitoring Devices Based on Pulse Wave Transit Time and Pulse Arrival Time: A Review
Continuous blood pressure (BP) monitoring is of great significance for the real-time monitoring and early prevention of cardiovascular diseases. Recently, wearable BP monitoring devices have made great progress in the development of daily BP monitoring because they adapt to long-term and high-comfort wear requirements. However, the research and development of wearable continuous BP monitoring devices still face great challenges such as obvious motion noise and slow dynamic response speeds. The pulse wave transit time method which is combined with photoplethysmography (PPG) waves and electrocardiogram (ECG) waves for continuous BP monitoring has received wide attention due to its advantages in terms of excellent dynamic response characteristics and high accuracy. Here, we review the recent state-of-art wearable continuous BP monitoring devices and related technology based on the pulse wave transit time; their measuring principles, design methods, preparation processes, and properties are analyzed in detail. In addition, the potential development directions and challenges of wearable continuous BP monitoring devices based on the pulse wave transit time method are discussed.
Journal Article
Doping of polymer optical fiber cladding in the solution of water and methanol at elevated temperature
The cladding of PMMA based polymer optical fibers (POFs) is doped by Rhodamine 6G (Rh6G) in the solution composed of water and methanol. Methanol is added in order to lower the doping temperature compared to that of pure water. Results show that addition of methanol, like raising temperature, can effectively accelerate the doping process. It is also found that there is a critical doping temperature for the solution of given methanol content. Above that temperature, the doping process dramatically impairs the fiber and the fiber loss increases too much for further application. In addition, Microscope observation of cross-sections of doped fibers indicate that Rh6G only diffuses into the cladding. Concentration measurement of Rh6G in the cladding and the core of doped fibers confirms that there is almost no Rh6G in the core. In short, this study reveals that the doping process of PMMA based POFs can be accelerated by adding methanol into water at the same temperature. Most importantly, the solution of methanol and water may be able to dissolve those dopants that are insoluble in pure water, making the aqueous solution based doping method suitable for more dopants.
Journal Article