High-energy cosmic-ray electrons and positrons (CREs), which lose energy quickly during their propagation, provide a probe of Galactic high-energy processes and may enable the observation of ...phenomena such as dark-matter particle annihilation or decay. The CRE spectrum has been measured directly up to approximately 2 teraelectronvolts in previous balloon- or space-borne experiments, and indirectly up to approximately 5 teraelectronvolts using ground-based Cherenkov γ-ray telescope arrays. Evidence for a spectral break in the teraelectronvolt energy range has been provided by indirect measurements, although the results were qualified by sizeable systematic uncertainties. Here we report a direct measurement of CREs in the energy range 25 gigaelectronvolts to 4.6 teraelectronvolts by the Dark Matter Particle Explorer (DAMPE) with unprecedentedly high energy resolution and low background. The largest part of the spectrum can be well fitted by a 'smoothly broken power-law' model rather than a single power-law model. The direct detection of a spectral break at about 0.9 teraelectronvolts confirms the evidence found by previous indirect measurements, clarifies the behaviour of the CRE spectrum at energies above 1 teraelectronvolt and sheds light on the physical origin of the sub-teraelectronvolt CREs.
Summary
What is known and Objective: Clinical investigations into postoperative intravenous patient‐controlled analgesia (PCA) have indicated interindividual differences in fentanyl consumption. ...Cytochrome P450 3A4 (CYP3A4) is the main metabolism enzyme of fentanyl, and single nucleotide polymorphisms within the CYP3A4 gene may contribute to the variability of fentanyl analgesic efficacy. The aim of this study was to investigate whether the most common genetic variation in Chinese, CYP3A4*1G, has an impact on the fentanyl consumption for intravenous PCA in Chinese Han women undergone abdominal total hysterectomy.
Methods: A total of 79 female patients (American Society of Anesthesiologist physical status I or II) scheduled to undergo elective abdominal total hysterectomy were enrolled. All patients received combined spinal–epidural anaesthesia with bupivacaine. Intravenous fentanyl PCA was provided postoperatively for satisfactory analgesia. The doses of fentanyl consumption were recorded 2, 4, 24 and 48 h after the initiation of PCA postoperatively. Pain at rest and adverse effects were measured with rating scales. CYP3A4*1G was screened by means of direct sequencing and further confirmed by polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP).
Results and Discussion: Forty‐six patients were GG homozygotes, 27 patients were GA heterozygotes, and six patients were AA homozygotes, respectively. The distribution of the CYP3A4*1G allele was consistent with Hardy–Weinberg equilibrium (P > 0·05). At 2 and 4 h, the doses of fentanyl required for patients with GA/AA genotypes were 80·0 (45·0, 112·5) μg and 120·0 (80, 173·8) μg, respectively, and significantly lower than those for GG homozygotes 91·3 (80·0, 125·0) μg and 169·0 (112·5, 226·3) μg, respectively, P < 0·05. There was trend of decreasing fentanyl consumption at 24 and 48 h in patients with GA/AA genotypes, relative to GG homozygotes, but the difference was not statistical significant (P > 0·05).
What is new and Conclusions: CYP3A4*1G has an impact on the analgesic effect of fentanyl in Chinese Han subjects. Further validation of our results in a well‐powered study would be helpful.
Hydrogen generation via hydrolysis of 250
mg hydrogenated Mg
3La and La
2Mg
17 in 100
ml water has been investigated at 298
K. Hydrolysis reactions of hydrogenated Mg
3La and La
2Mg
17 obtained by ...induction melting and then hydrogenated at 298
K is found to be fast when they are immersed in water. The hydrolysis reaction of hydrogenated Mg
3La almost completes within 21
min with faster kinetics and higher yield than those obtained of hydrogenated La
2Mg
17. The hydrogen production rate is 43.8
ml
min
−1
g
−1 of hydrogen in the first 20
min of reaction compared to a conversion yield of 88% for hydrogenated Mg
3La and 40.1
ml
min
−1
g
−1 of hydrogen in the first 20
min of reaction for hydrogenated La2Mg17. It is related to the catalytic effect of LaH
3 formed during the hydriding process, accentuating corrosion of MgH
2 greatly. The experimental curves of hydrogen generation kinetics at room temperature are well fitted by the Avrami–Erofeev equation. The reaction mechanism of hydrogenated Mg
3La and La
2Mg
17 was also discussed.
Intense near-infrared (NIR) emission around 1534 nm has been obtained from ZnO-SiO2:Er3+ composites upon broadband ultraviolet light excitation. Remarkably, enhancement of the NIR emission as much as ...20 times was achieved by optimal codoping with Li+ ions. To elucidate the relevant mechanisms, comprehensive spectroscopic measurements have been performed on ZnO-SiO2 composites with and without Er3+ ions doping. Photoluminescence spectroscopy and fluorescence decay dynamics clearly verify the efficient energy transfer from ZnO quantum dots (QDs) to Er3+ ions. Our results have not only demonstrated an efficient approach of color down-conversion but also indicated that ZnO-SiO2:Er3+ composites could be a promising material for optical amplifier using broadband UV pumping.
Concrete structures in cold regions are exposed to cyclic freezing and thawing environment, leading to degraded mechanical and fracture properties of concrete due to microstructural damage. While the ...X-ray micro-/nano-computed tomography technology has been implemented to directly observe concrete microstructure and characterize local damage in recent years, the freeze-thawed damage evolution processes and its effect on overall mechanical performance are not well understood. In this paper, the X-ray nano-computed tomography technology and micro-scale cohesive zone model are combined to quantitatively investigate microstructural damage evolution and its effect on fracture behavior of freeze-thawed concrete samples in three-point bending tests. A two-level micro-to-macro scale finite element model is developed based on computed tomography microstructural images with microcracks due to freeze-thaw cycles. The macroscopic load–deflection curves and fracture energies are simulated and compared favorably with experimental results. Simulation results demonstrate that microcracks caused by freeze-thaw actions are the primary reason for degradation of concrete mechanical properties. Fracture behaviors of frost-damaged concrete with different mortar and interfacial transition zone strength and fracture constants are also simulated and discussed. The combined X-ray nano-computed tomography technology and cohesive zone model proposed is effective in characterizing fracture behavior of concrete and capturing freeze-thaw cycle-induced microstructural damage evolution and its effect on fracture process of concrete.
Thermodynamic behavior has been extensively used to evaluate the stability of materials and predict the direction of the chemical reaction at different pH values, temperatures, potentials, and ion ...concentrations. Although researching efforts on Sn species in an aqueous solution system (Sn/H2O) of acid, alkali, and salt have been reported, scattered data leads to the inefficiency of a thermodynamic method in the practical application. This article provides a brief review on the potentialpH diagram for Sn/H2O system, which reflects the thermodynamic behavior of Sn species in an aqueous solution and extracts thermodynamic data for the practical application of Sn species. Firstly, the relationship of the thermodynamic behavior, potential-pH diagram, and equilibrium relations of Sn species for Sn/H2O system was overviewed. Additionally, the potential-pH diagram of Sn/H2O system at different temperatures (298 K, 373 K, and 550 K), dissolved Sn activities (1, 10?1, 10?3, and 10?6), and the potential-pH diagram of the Sn species in a chloridion aqueous solution (Sn/H2O-Cl) was summarized. Finally, the application prospect of the potential-pH diagram for Sn/H2O system was investigated in the intelligent simulation of Sn metallurgy and the practical application of Sn materials.
As a relatively recent cultural invention in human evolution, reading is an important gateway to personal development and socioeconomic success. Despite the well documented individual differences in ...reading ability, its neuroanatomical correlates have not been well understood, largely due to the fact that reading is a complex skill that consists of multiple components. Using a large sample of 416 college students and 7 reading tasks, the present study successfully identified three uncorrelated components of reading ability: phonological decoding, form-sound association, and naming speed. We then tried to predict individuals' scores in these components from their gray matter volume (GMV) on a subset of participants (N = 253) with high-quality structural images, adopting a multivariate support vector regression analysis with tenfold cross-validation. Our results revealed distinct neural regions that supported different aspects of reading ability: whereas phonological decoding was associated with the GMV in the left superior parietal lobe extending to the supramarginal gyrus, form-sound association was predicted by the GMV in the hippocampus and cerebellum. Naming speed was associated with GMV in distributed brain regions in the occipital, temporal, parietal, and frontal cortices. Phonological decoding and form-sound association were uncorrelated with general cognitive abilities. However, naming speed was correlated with intelligence and processing speed, and some of the regions that were predictive of naming speed also predicted these general cognitive abilities. These results provide further insights on the cognitive and neural architecture of reading and the structural basis of individual differences in reading abilities.
Background:
Neuropathic pain after nerve injury is severe and intractable, and current drug and non‐drug therapies offer very limited pain relief. Hyperbaric oxygen (HBO
2) has been clinically used ...for protection of the nervous system after acute injury. We investigated whether HBO
2 treatment could prevent and/or attenuate neuropathic pain in animals and in patients.
Methods:
Mechanical allodynia and thermal hyperalgesia and neurochemical alterations of neuropathic pain were analysed in male, adult, Sprague‐Dawley rats with sciatic nerve injury. Clinical trials were conducted in patients with idiopathic trigeminal neuralgia.
Results:
Repetitive HBO
2 treatment a combination of pressure at 3 atmosphere absolute (ATA) and pure oxygen greatly inhibited behavioural signs of neuropathic pain manifested as thermal hyperalgesia and mechanical allodynia. Such an HBO
2 treatment also inhibited nerve injury‐induced induction of c‐Fos and activation of astrocytes and increased phosphorylation of NR2B receptor and the subsequent Ca
2+‐dependent signals in rats. Neither high pressure (up to 3 ATA) nor pure oxygen alone resulted in analgesic effect. In clinical trials, one course of HBO
2 therapy (10 consecutive days) produced a rapid‐onset, dose‐dependent and long‐lasting analgesic effects evidenced by the decreased doses of carbamazepine required for keeping patient pain at a minimum and decreased scores of visual analogue scales, which was used for patient's self‐evaluation.
Conclusions:
These findings support that HBO
2 therapy is an effective approach for treating neuropathic pain in both animals and human beings and suggest that neural protection, anti‐inflammation and inhibition of nerve injury‐induced altered neural activity may contribute to the analgesic effect of HBO
2 therapy.
In this work, the aluminum–water reaction induced by Fe–B, Co–B and Ni–B particles was studied. The catalysts were mixtures of the metal boride and metallic particles. The chainlike Fe–B catalyst ...forms a network structure under the influence of an external magnetic field and has a large specific surface area. Aggregated particles of Co–B and Ni–B catalyst have small specific surface area. Catalytic activity in the initial corrosion of aluminum increases with increasing Fe–B content because of the large specific surface area and the formation of a micro galvanic cell. However, the amount of hydrogen generated slowly decreases with increasing amount of Co–B and Ni–B. The activity of Fe–B, Co–B and Ni–B in the initial Al/H2O reaction decreases in the order Fe–B > Ni–B > Co–B. The calculated apparent activation energies in the presence of Fe–B, Co–B and Ni catalysts are 38.2, 39 and 29.6 kJ mol−1, respectively. Aluminum is rapidly and completely corroded in a weakly alkaline solution (pH < 10) after consecutive additions of Al batches because of high concentrations of OH− in the local domain and an increase in the amount of Al(OH)3 precipitate.
•The chainlike Fe–B catalyst forms a network structure.•The catalytic activity in the initial Al/H2O reaction at 45°Cis Fe–B > Ni–B > Co–B.•Aluminum is rapidly corroded after consecutive additions of Al batches.•The high concentrations of OH− in the local domain triggers the corrosion of Al.
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