The TDR of CEPC is aimed at the key science and technology problems and makes preparations for the real project. This paper will describe the progress of mechanical system including the regular ...supports and transport vehicle design, the mockup plan, the installation scenario of machine detector interface (MDI) and the movable collimator, as well as the TDR plans of mechanical system.
Magnesium hydride MgH2 is an attractive hydrogen storage material because of its high volumetric and gravimetric densities, inexpensiveness and abundance. However, its high dehydrogenation ...temperature resulted from the unfavorable thermodynamic and kinetic barriers limits its practical applications. Herein, we first propose an efficient strategy for remarkably enhancing the dehydrogenation properties of MgH2 by sequential-doping of nickel (Ni) and graphene (G) via mechanical milling. This method can not only accelerate the refinement of MgH2 grains and particles, but also significantly decrease its dehydrogenation temperature relative to G single-doping and Ni/G simultaneous-doping systems. First-principles calculations indicate that the excellent dehydrogenation properties of Ni/G sequential-doped MgH2 system are closely associated with the dual effects involving Ni solid-solution in MgH2 lattice and interfacial catalysis between G-supported Ni catalysts and MgH2 matrix. Upon these effects, the dehydrogenation enthalpy and dehydrogenation activation energy of MgH2 are remarkably decreased. The finding provides a new insight into the development of high performance Mg/MgH2 based hydrogen storage composites by optimizing the doping sequence of additives.
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•An efficient method for enhancing the dehydrogenation properties of MgH2 is proposed.•The doping sequence of additives tunes the dehydrogenation properties of MgH2.•The dual catalytic effects of Ni and graphene are realized by sequential-doping.•The catalytic mechanisms are analyzed by experimental and first-principles studies.•A new insight is provided by optimizing the doping sequence of additives.
Surgical site infections after orthopaedic surgery using fracture fixation devices or endosseous implants create major surgical challenges with severe adverse effects, such as osteomyelitis. These ...infections are frequently caused by Staphylococcus aureus, often with high resistance to antibiotics, such as methicillin-resistant Staphylococcus aureus (MRSA). Due to the formation of impenetrable biofilms on implant surfaces, systemic antibiotic treatment has become exceedingly difficult. New solutions are pursued by combining several drugs using a controlled delivery system from specifically engineered implant surfaces. A sol-gel coating on titanium implants was previously developed with 20 wt % vancomycin and 30 wt % farnesol, with suppression of MRSA in vitro. The present study investigated the efficacy of sol-gel film coatings for controlled dual local delivery over 4 weeks utilising a rat infection model. The findings confirmed the viability of this new concept in vivo based on the differences observed between coatings containing vancomycin alone (SGV) and the dual-drug-containing coating with vancomycin and farnesol (SGVF). While both the SGVF and SGV coatings facilitated excellent preservation of the osseous microarchitecture, SGVF coating displayed a slightly higher potency for suppressing MRSA infiltration than SGV, in combination with a lower reactive bone remodelling activity, most likely by disturbing biofilm formation. The next step for advancing the concept of dual-drug delivery from sol-gel coatings to the clinic and confirming the promising effect of the SGVF coatings on reactive bone remodelling and suppressing MRSA infiltration is a study in a larger animal species with longer time points.
The four hydrogen storage systems including pure MgH
2
, MgH
2
-5 wt%NiCl
2
, MgH
2
-10 wt%NiCl
2
and MgH
2
-10 wt%NiCl
2
-10 wt%graphene were prepared by ball-milling in this work. Using ...experimental X-ray diffraction, scanning electron microscopy and differential scanning calorimetry testing methods in combination with first-principle calculations, the dehydrogenation properties and mechanisms of NiCl
2
single-doped and NiCl
2
-graphene co-doped MgH
2
composites were systematically investigated. Experimental results show that the NiCl
2
single-doping is conductive to decreasing the size of MgH
2
grains and particles. The co-doping of NiCl
2
and graphene not only reduces the size of MgH
2
grains and particles, but also contributes to the uniformity of MgH
2
particles. As compared with milled pure MgH
2
, the dehydrogenation peak temperatures are decreased by 24 °C and 47 °C for the 10 wt%NiCl
2
single-doped and 10 wt%NiCl
2
-10 wt%graphene co-doped MgH
2
systems, respectively. It is demonstrated that the co-doping of NiCl
2
and graphene exhibits the synergistic effects of confinement and catalysis on improving the dehydrogenation properties of MgH
2
. The first-principle calculations indicate that the co-doping of NiCl
2
and graphene leads to the distortion of MgH
2
atomic-configuration and results in the charge transfer between the dopants and MgH
2
, which induce the weakened structural stability and decreased dehydrogenation enthalpy of MgH
2
.
Reservoir spaces, such as vesicles, 'secondary' amygdales, dissolution caverns and geodes, are widely developed in the Emeishan basaltic lavas in the Zhoudaping section, Leshan, west Sichuan, China. ...The dissolution characteristics, cementation sequences, hydrothermal activity stages, as well as fluid types, and their effects on the reservoir capacity were investigated for each stage. Macroscopically, the dissolution features present as irregular dissolution zones, which are characterised by a light red colour. Microscopically, in the dissolved zone, the cementation-filling minerals are associated with complex fill sequences, such as quartz/laumontite/chlorite-chlorite/saponite-epidote/celadonite-cryptocrystalline chlorite-laumontite/calcite/quartz. The U-Pb geochronology shows that the age of chlorite fill in amygdales is 235.3 ± 19.6 Ma; the coarse-crystalline quartz inside dissolution caverns/geodes, 124.47 ± 5.63 to 123.84 ± 5.63 Ma; and the siliceous mineral-filled amygdales, 118.34 ± 3.70 to 114.08 ± 3.76 Ma, which correspond to the early Late Triassic and the mid-late Early Cretaceous, respectively. Combined with geochemical characteristics of post-dissolution fill, the amygdales are affected by two stages of hydrothermal activity: chlorite filling of the amygdales corresponds to post-magma hydrothermal fluids during the early Late Triassic, and the siliceous mineral-fill in amygdales corresponds to deep-sourced hydrothermal fluids during the mid-late Early Cretaceous. The geodes/dissolution caverns result from a single stage of hydrothermal activity related to the mid-late Early Cretaceous deep-source low-temperature hydrothermal fluid. The Late Triassic post-magma hydrothermal fluids are generally destructive to pores, and tectonic-related dissolution of deep-sourced hydrothermal fluids has a positive effect on the formation of reservoir spaces, greatly enhancing fluid storage and flow capacities of the volcanic lavas. We recommend the multi-stage hydrothermal dissolution during Late Triassic-Early Cretaceous and faults, fractures and columnar joints be the focus of hydrocarbon exploration.
KEY POINTS
The reservoir spaces developed in the Zhoudaping section, such as amygdales, dissolution caverns and geodes, were controlled by different stages and types of hydrothermal alteration.
Amygdales are the product of two hydrothermal events, which correspond to post-magma hydrothermal fluids during the early Late Triassic and the deep-sourced hydrothermal fluids of the mid-late Early Cretaceous. Geodes/dissolution caverns are affected by deep-source low-temperature hydrothermal fluids in the mid-late Early Cretaceous.
The multi-stage hydrothermal dissolution during the Late Triassic-Early Cretaceous and faults, fractures and columnar joints should be the focus of hydrocarbon exploration.
A new Venus‐ESD‐Chamber (VEC) and peripheral systems were designed and built to simulate Venus lightning. It consists of three subsystems (a) electrostatic discharge (ESD) generation, (b) ...environmental pressure, temperature, gas composition control & monitoring, and (c) optical and non‐optical sensors. We conducted arc discharge experiments in air, in CO2, and in Venus major gas mixture (CO2‐N2, 96.5% ± 1.5%:3.5% ± 1.5%) under 10, 350, 700, and 1,000 mbar pressures, that correspond to the 50–75 km altitude range in the cloud layer of Venus. Plasma and Raman spectra, plus gas sensors, and GC‐MS were used to identify the ESD products and to semi‐quantify CO and O3 generated by ESD. We have found all species of free radicals that have been found in previous simulation studies using different discharge technologies, including some important species in CO2‐N2 system, nitrogen oxides and CN. In addition, we found three species (O3, N2+, and C2) that have not been previously reported. Our results suggest that electron flux and kinetic energy are the determining factors for the type of generated free radical species and gas pressure plays a less important role. We found that the quantity of CO changes with the type of ESD. The detection of O3 in this study suggests that lightning might be one of the sources of O3 observed in the Venusian atmosphere. OI emission line at 777.4 nm is the most prominent line in our plasma spectra of FD, consistent with the intense optical flash observed by the Lightning and Airglow Camera (LAC) on the Akatsuki mission.
Plain Language Summary
Lightning is a common phenomenon on Earth and plays an important role in atmospheric chemistry as well as in atmosphere‐surface interaction. The thick atmosphere and strong convective activities in Venus cloud layers could ignite lightning. Evidence of lightning on Venus (optical and electric types) has been reported since the 1970s, including the observation made by the most recent mission Akatsuki in 2020. Here, we report the detection of 15 types of free radicals generated during a set of arc‐type electric discharges in simulated Venus atmosphere with two major Venus gases (CO2 & N2) and in a pressure range corresponding to the Venus cloud layer (50–75 km altitude range). These free radicals are ions and neutral atoms/molecules in excited states, which have extremely high chemical reactivity and high kinetic energy. They could play crucial roles in Venus atmospheric chemistry and might be helpful to interpret some past mission observations for example, nitrogen oxides and O3.
Key Points
Building a Venus‐ESD chamber enables simulation of Venus lightning and radical sensing
Arc discharge was realized to simulate lightning in the cloud layer of Venus
15 types of free radicals and excited atoms/molecules were characterized using four sensors
The high dehydrogenation temperature of magnesium hydride MgH2 is still the main obstacle to its practical application as a solid-state hydrogen storage medium. Using experimental and ...first-principles calculations approaches, we, for the first time, investigate the catalytic effect and mechanism of nickel phthalocyanine on the dehydrogenation properties of MgH2. The results display that a small amount of nickel phthalocyanine can promote MgH2 dehydrogenation at significantly decreased temperatures by more than 90 °C relative to milled pristine or graphene-added MgH2 system. However, the agglomeration of MgH2 particles is not evidently alleviated through nickel phthalocyanine addition. When MgH2 is milled with graphene firstly and then the obtained mixture is further milled with nickel phthalocyanine, the dehydrogenation properties and agglomeration of MgH2 particles can be synergistically improved to some extent. The first-principles calculations of dehydrogenation enthalpy and binding energy account for the experimental differences in catalysis and aggregation-resistance abilities of nickel phthalocyanine and graphene on MgH2 particles. Notably, the NiN4-inserted graphene is predicted to be an ideal additive for MgH2, which combines the synergetic catalysis-confinement effect of nickel phthalocyanine and graphene on MgH2 particles. Analysis of electronic structures reveals that the excellent catalytic effect of nickel phthalocyanine on MgH2 can be ascribed to the more electron transfer between nickel phthalocyanine and MgH2, which induces the significantly weakened bond strength of MgH and decreased dehydrogenation enthalpy of MgH2.
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•NiPc exhibits superior catalytic effect on MgH2 dehydrogenation.•Multi-addition of NiPc and G can improve dehydrogenation and agglomeration of MgH2.•Dehydrogenation enthalpy and binding energy of MgH2-NiPc system are calculated.•Catalytic effect of NiPc on MgH2 is associated with electron transfer between them.•NiN4-inserted G is predicted to be an ideal catalysis-confinement additive for MgH2.
1. This study investigated the effect of dietary calcium (Ca) levels on growth performance, bone development and Ca transporter gene expression levels in the small intestine of broiler chickens.
2. ...On the day of hatch, 350, Ross 308 male broilers were randomly allotted to one of five treatments with five replicate pens each and 14 birds per pen. Dietary Ca levels in feed were 5.0, 7.0, 9.0, 11.0 and 13.0 g/kg, in which 9.0 g/kg was in the control diet. All diets contained 4.5 g/kg non-phytate phosphorus (NPP).
3. The increase in dietary Ca levels from 5.0 to 13.0 g/kg did not affect the growth performance of 1- to 18-day-old broilers (P > 0.05).
4. Increasing the Ca levels linearly increased the ash weight and the contents of ash, Ca and phosphorus (P) in the tibia of broilers at 18 days of age (P < 0.05). The contents of ash, Ca and P in broilers fed with 9.0 g/kg Ca were higher than those in birds fed with 5.0 g/kg Ca (P < 0.05).
5. Increasing the Ca levels linearly decreased mRNA expression levels of the Ca-binding protein 28-kDa (CaBP-D28k), plasma membrane Ca-transporting ATPase 1b (PMCAlb), sodium (Na)/Ca exchanger 1 (NCX1), nuclear vitamin D receptor (nVDR) and membrane vitamin D receptor (mVDR) in the duodenum of broilers at 18 d of age (P < 0.05). Similar results were seen in the jejunum and ileum. Broilers fed 9.0-13.0 g/kg Ca in feed had lower mRNA expression levels of CaBP-D28k and PMCAlb in the small intestine than birds fed 5.0 g/kg Ca in feed (P < 0.05).
6. The data indicated that low levels of dietary Ca stimulated its transporter gene transcription and promoted absorption, but high levels of Ca inhibited transporter gene expression and prevented excessive absorption in the small intestine of broiler chickens.
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