HIAF (High Intensity heavy ion Accelerator Facility), a new facility planned in China for heavy ion related researches, consists of two ion sources, a high intensity Heavy Ion Superconducting Linac ...(HISCL), a 45 Tm Accumulation and Booster Ring (ABR-45) and a multifunction storage ring system. The key features of HIAF are unprecedented high pulse beam intensity and versatile operation mode. The HIAF project aims to expand nuclear and related researches into presently unreachable region and give scientists possibilities to conduct cutting-edge researches in these fields. The general description of the facility is given in this article with a focus on the accelerator design.
A highly facile one‐pot ethylene glycol‐assisted solvothermal process was employed to fabricate bismuth oxybromide (BiOBr) with oxygen‐deficient defects. These defects played an indispensable role ...for superior photocatalytic CO2 reduction, in which the as‐prepared sample demonstrated a remarkable improvement of 3.3 and 5.7‐fold for CH4 production over pristine BiOBr and P25, respectively. The enhancement could be attributed to the presence of oxygen vacancies, which acted as the active sites for CO2 adsorption and activation. In addition, the oxygen–deficiency–induced defect states could effectively trap photogenerated electrons, thus improving the separation of the electron–hole pairs and significantly slow down the recombination rate of charge carriers. On top of that, oxygen‐deficient BiOBr exhibited long term stability (>50 hours of catalytic reaction) for CO2 photoreduction under simulated solar light, where no reducing agent or any post‐treatment was needed to regenerate the oxygen vacancies.
Oxygen vacant sites as active sites: Oxygen‐deficient BiOBr exhibits superior performance for CO2 reduction. This could be attributed to the CO2 molecules tendency to adsorb on the oxygen vacant sites with abundant localized electrons, in which CO2 is spontaneously reduced to CO and further reduced to CH4 by a multi‐electron process.
Growing concerns of water pollution by dye pollutants from the textile industry has led to vast research interest to find green solutions to address this issue. In recent years, heterogeneous ...photocatalysis has harvested tremendous attention from researchers due to its powerful potential applications in tackling many important energy and environmental challenges at a global level. To fully utilise the broad spectrum of solar energy has been a common aim in the photocatalyst industry. This study focuses on the development of an efficient, highly thermal and chemical stable, environmentally friendly and metal-free graphitic carbon nitride (g-C3N4) to overcome the problem of fast charge recombination which hinders photocatalytic performances. Nitrogen-doped carbon quantum dots (NCQDs) known for its high electronic and optical functionality properties is believed to achieve photocatalytic enhancement by efficient charge separation through forming heterogeneous interfaces. Hence, the current work focuses on the hybridisation of NCQDs and g-C3N4 to produce a composite photocatalyst for methylene blue (MB) degradation under LED light irradiation. The optimal hybridisation method and the mass loading required for maximum attainable MB degradation were systematically investigated. The optimum photocatalyst, 1 wt% NCQD/g-C3N4 composite was shown to exhibit a 2.6-fold increase in photocatalytic activity over bare g-C3N4. Moreover, the optimum sample displayed excellent stability and durability after three consecutive degradation cycles, retaining 91.2% of its original efficiency. Scavenging tests were also performed where reactive species, photon-hole (h+) was identified as the primary active species initiating the pollutant degradation mechanism. The findings of this study successfully shed light on the hybridisation methods of NCQDs which improve existing g-C3N4 photocatalyst systems for environmental remediation by utilising solar energy.
Display omitted
•Nitrogen-doped CQDs were hybridized with g-C3N4 through a facile synthesis approach.•The NCQD/g-C3N4 hybrid showed high efficiency toward MB degradation under LED light.•The best hybridization approach and the effect of NCQD loading on g-C3N4 were studied.•The optimum 1 wt% NCQD/g-C3N4 exhibited a 2.6-fold increase in activity over g-C3N4.•A plausible photocatalytic mechanism over NCQD/g-C3N4 hybrid composite was proposed.
Natural zeolite membranes, directly sectioned from mineral deposits, have been previously reported to show molecular sieve characteristics in selective separation of water and hydrated cations. ...Although a high removal of cations was observed, the low water flux was a limitation for any potential industrial applications. In this study novel clinoptilolite-based phosphate composite membranes were prepared by dry pressing of mixed powder materials followed by high temperature autoclave steaming and characterized by XRD, SEM-EDX. Their performance for pervaporative water desalination was examined using different levels of salinity in a temperature range of 25–95°C and feed side pressure of 1atm. At 1400ppm Na feed salinity and 95°C, a water flux of 15kg/m2h and over 95% removal of Na+ were obtained. The water flux achieved was about 10 times higher than the flux obtained using natural zeolite rock membranes. Introducing phosphate into the composite membranes appears to provide not only mechanical strength, through the possible chemical bonding between zeolite particles and the in-situ phosphate cement, but also to create a chemically favorable interface between zeolite crystals. Such interface might facilitate the desalination process bypassing the technical difficulties of ion leakage/diffusion through the inter-crystal spaces commonly associated with synthetic zeolite membranes.
•Natural clinoptilolite-phosphate composite membranes.•High temperature water desalination process.•98+% of Na+ removal was achieved at 50°C for a saline water with 1400ppm of sodium.•High water flux of ~15kg/m2h was achieved at 95°C.
Universal access to clean water has been a global ambition over the years. Photocatalytic water disinfection through advanced oxidation processes has been regarded as one of the promising methods for ...breaking down microbials. The forefront of this research focuses on the application of metal‐free photocatalysts for disinfection to prevent secondary pollution. Graphitic carbon nitride (g‐C3N4) has achieved instant attention as a metal‐free and visible‐light‐responsive photocatalyst for various energy and environmental applications. However, the photocatalytic efficiency of g‐C3N4 is still affected by its rapid charge recombination and sluggish electron‐transfer kinetics. In this contribution, two‐dimensionally protonated g‐C3N4 was employed as metal‐free photocatalyst for water treatment and demonstrated 100 % of Escherichia coli within 4 h under irradiation with a 23 W light bulb. The introduction of protonation can modulate the surface charge of g‐C3N4; this enhances its conductivity and provides a “highway” for the delocalization of electrons. This work highlights the potential of conjugated polymers in antibacterial application.
Water, water everywhere: The efficiency of graphitic carbon nitride (g‐C3N4) in photocatalytic water disinfection is plagued by its rapid charge recombination and sluggish electron‐transfer kinetics. Protonation of g‐C3N4 can enhance its conductivity and provide a “highway” for the delocalization of electrons. Consequently, protonated g‐C3N4 demonstrated 100 % destruction of E. coli within 4 h under low‐power household light irradiation.
In this paper, we consider the modeling and (robust) control of a DC-DC Boost converter. In particular, we derive a mathematical model consisting of a constrained switched differential inclusion that ...includes all possible modes of operation of the converter. The obtained model is carefully selected to be amenable for the study of various important robustness properties. For this model, we design a control algorithm that induces robust, global asymptotic stability of a desired output voltage value. The guaranteed robustness properties ensure proper operation of the converter in the presence of noise in the state, unmodeled dynamics, and spatial regularization to reduce the high rate of switching. The establishment of these properties is enabled by recent tools for the study of robust stability in hybrid systems. Simulations illustrating the main results are included.
Fracture Modes in Human Teeth Lee, J.J.-.W.; Kwon, J.-Y.; Chai, H. ...
Journal of dental research,
03/2009, Volume:
88, Issue:
3
Journal Article
Peer reviewed
The structural integrity of teeth under stress is vital to functional longevity. We
tested the hypothesis that this integrity is limited by fracture of the enamel.
Experiments were conducted on molar ...teeth, with a metal rod loaded onto individual
cusps. Fracture during testing was tracked with a video camera. Two longitudinal
modes of cracking were observed: median cracking from the contact zone, and margin
cracking along side walls. Median cracks initiated from plastic damage at the contact
site, at first growing slowly and then accelerating to the tooth margin. Margin
cracks appeared to originate from the cemento-enamel junction, and traversed the
tooth wall adjacent to the loaded cusp from the gingival to the occlusal surface. All
cracks remained confined within the enamel shell up to about 550 N. At higher loads,
additional crack modes—such as enamel chipping and delamination—began to manifest
themselves, leading to more comprehensive failure of the tooth structure.
Design of a compact structure cancer therapy synchrotron Yang, J.C.; Shi, J.; Chai, W.P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2014, Volume:
756
Journal Article
Peer reviewed
HIMM, a new compact accelerator facility dedicated to carbon cancer therapy, has been designed and is presently under construction. The synchrotron has a compact structure that exhibits a ...circumference of only 56.2m. The charge exchange injection (CEI) method is adopted for synchrotron injection with a carbon-ion energy of 7MeV/u. The third-order resonance and RF-Knock Out scheme are adopted in this machine. The general design of the machine and injection/extraction simulation results is discussed in this paper.
Status of the HIRFL–CSR complex Yuan, Y.J.; Yang, J.C.; Xia, J.W. ...
Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms,
12/2013, Volume:
317
Journal Article
Peer reviewed
•HIRFL is in a very positive state and can provide all ion species with maximum energy to 1GeV/u (A/q=2).•Present status of HIRFL complex is given as well as the new progress on operation and ...improvement.•With emphasize on HIRFL–CSR project, main features realized during the commissioning and operation are described in detail.•The progress on physics experiments and hadron cancer therapy are also presented.
The HIRFL–CSR, as an upgrade of the HIRFL, has been put into operation since 2008. Together with a series of improvements of injector cyclotrons, the HIRFL is in a very good state and can provide all ion species from proton to uranium with energy variable from ion source energy to 1GeV/u (A/q=2). Present status of the HIRFL–CSR complex is given. Main features realized during the commissioning and operation are described in detail. The progress on physics experiments and cancer therapy are also presented.
PDF
