We have performed a systematic high-momentum-resolution photoemission study on ZrTe5 using 6-eV photon energy. We have measured the band structure near the Γ point, and quantified the gap between the ...conduction and valence band as 18≤Δ≤29 meV. We have also observed photon-energy-dependent behavior attributed to final-state effects and the three-dimensional (3D) nature of the material's band structure. Our interpretation indicates the gap is intrinsic and reconciles discrepancies on the existence of a topological surface state reported by different studies. The existence of a gap suggests that ZrTe5 is not a 3D strong topological insulator nor a 3D Dirac semimetal. Therefore, our experiment is consistent with ZrTe5 being a 3D weak topological insulator.
Summary
Electron microscopy has been applied widely to study the interaction of nanomaterials with proteins, cells and tissues at nanometre scale. Biological material is most commonly embedded in ...thermoset resins to make it compatible with the high vacuum in the electron microscope. Room temperature sample preparation protocols developed over decades provide contrast by staining cell organelles, and aim to preserve the native cell structure. However, the effect of these complex protocols on the nanomaterials in the system is seldom considered. Any artefacts generated during sample preparation may ultimately interfere with the accurate prediction of the stability and reactivity of the nanomaterials. As a case study, we review steps in the room temperature preparation of cells exposed to silver nanomaterials (AgNMs) for transmission electron microscopy imaging and analysis. In particular, embedding and staining protocols, which can alter the physicochemical properties of AgNMs and introduce artefacts thereby leading to a misinterpretation of silver bioreactivity, are scrutinized. Recommendations are given for the application of cryogenic sample preparation protocols, which simultaneously fix both particles and diffusible ions. By being aware of the advantages and limitations of different sample preparation methods, compromises or selection of different correlative techniques can be made to draw more accurate conclusions about the data.
Lay description
With increasing commercialization of silver nanomaterials (AgNMs) comes a concomitant need to understand occupational health, public safety and environmental implications of these materials. Nanoscale studies of the complex bio‐nano interface lie at the heart of technical challenges. Despite numerous reports, there is no consensus regarding biological mechanisms enacted by AgNMs. Powerful new electron microscopy techniques can be used to visualize the interaction of the AgNMs with tissues. However, it is extremely difficult to preserve this nanomaterial within cells or tissues for imaging in these microscopes, to be able to accurately see how it behaves. The reason for this is that AgNMs can dissolve or change its chemistry in air, or in artificial fluids and chemicals, which are used to fix the structure of tissues to be able to visualize the NMs in electron microscopes. Unless great care is taken when preparing these materials, artefacts produced will lead us to incorrect conclusions about how they react with tissues. For example, we could incorrectly conclude that they can dissolve and interact with the nucleus causing genetic damage, when in fact, in the body they dissolve and form a nontoxic material, which does not cause any toxicity to the cells. Preparing samples for high powered microscopy analysis is a multistep process and the AgNMs may be susceptible to dissolution during each step. There has been an explosion in the literature concerning the toxicity of engineered nanomaterials; however, few papers consider whether or not the nanomaterial changes its format in body or during processing, so it is difficult to draw conclusions. The aim of this review is to discuss the pitfalls that can be made during preparation of these materials for microscopy and provide recommendations about how to prepare AgNMs, without creating unwanted artefacts.
Understanding the evolution of continental deformation zones relies on quantifying spatial and temporal changes in deformation rates of tectonic structures. Along the eastern boundary of the ...Pamir‐Tian Shan collision zone, we constrain secular variations of rock uplift rates for a series of five Quaternary detachment‐ and fault‐related folds from their initiation to the modern day. When combined with GPS data, decomposition of interferometric synthetic aperture radar time series constrains the spatial pattern of surface and rock uplift on the folds deforming at decadal rates of 1–5 mm/yr. These data confirm the previously proposed basinward propagation of structures during the Quaternary. By fitting our geodetic rates and previously published geologic uplift rates with piecewise linear functions, we find that gradual rate changes over >100 kyr can explain the interferometric synthetic aperture radar observations where changes in average uplift rates are greater than ~1 mm/yr among different time intervals (~101, 104–5, and 105–6 years).
Key Points
Decomposition of InSAR data reveals spatial variations of uplift rates on folds in the foreland of the Tian Shan and Pamir in NW China
Piecewise linear fits to geodetic and geologic uplift rates constrain temporal evolutions of uplift rates on five active folds
Our observations confirm propagation of deformation from the Tian Shan and Pamir mountain fronts into the Tarim Basin
Background
Personalized dosimetry for Lu-177-PSMA treatment requires multiple-time-point SPECT/CT scans to calculate time-integrated activity (TIA). This study evaluates two-time-point (TTP) methods ...for TIA calculation for kidneys and tumors.
Methods
A total of 18 patients treated with 3.7-7.4 GBq Lu-177 PSMA-617 were analyzed retrospectively, including 18 sets of left and right kidneys, as well as 45 tumors. Four quantitative SPECT/CT (4TP) were acquired at 2 h, 20 h, 40 h, 60 h (
n
= 11), or 200 h (
n
= 7) after treatment, and they were fit bi-exponentially as reference. The TTP method was fitted by a mono-exponential washout function using two selected imaging time points for kidneys. For tumors, one uptake and one washout phase were modeled, assuming linear (type I) and same (type II) uptake phase between 0 h to the first time point and mono-exponential washout thereafter. Two single-time-point (STP) methods were also implemented for comparison. TIA calculated by TTP and STP methods were compared with reference to the 4TP TIA.
Results
For the kidneys, the TTP methods using 20 h-60 h and 40 h-200 h had smaller mean absolute errors of 8.05 ± 6.05% and 4.95 ± 3.98%, respectively, as compared to other combinations of time points and STP methods. For tumors, the type I and type II TTP methods using 20h−60 h and 40–200 h had smaller mean absolute errors of 6.14 ± 5.19% and 12.22 ± 4.44%, and 8.31 ± 7.16% and 4.48 ± 7.10%, respectively, as compared to other TTP and STP methods.
Conclusion
The TTP methods based on later imaging time demonstrated fewer errors than the STP methods in kidney and tumor TIA. Imaging at 20 h−60 h and 40 h−200 h could simplify the dosimetry procedures with fewer TIA estimation errors.
Molten Salt Reactor (MSR) with Th-233U fuel cycle attracts more and more attention with its excellent performance such as desirable breeding capacity, low waste production and high inherent safety. ...Considering the fact that there is no available 233U in the nature, it is necessary to analyze the fuel transition from enriched 235U/Th to 233U/Th and then give a flexible transition scenario for a graphite-moderated MSR. By employing an in-house developed tool which is based on SCALE6.1, two scenarios, a Breeding and Burning (B&B) scenario and a Pre-breeding scenario, are studied. The evolution of the inventories of main nuclides, net 233U production and isothermal temperature coefficient are presented and discussed in the B&B scenario. It is found that the fuel transition can be achieved smoothly by using enriched uranium with greater than 40% concentration of 235U. The fuel transition can still be accomplished with 20% enriched uranium but takes a long double time of about 79 years. Meanwhile, we perform an analysis of the Pre-breeding scenario and conclude that it is efficient to produce 233U and the double time ranges from 2.07 years for the 10-day reprocessing to 10.7 years for the 180-day reprocessing. A comparison of these two scenarios is conducted, which indicates that the B&B scenario is more favorable than the Pre-breeding scenario from the aspect of resource utilization efficiency. Finally, a combined three-stage program for developing Th-based MSRs is proposed.
•The B&B scenario and the Pre-breeding scenario are analyzed to achieve the fuel transition from 235Uenr/Th to 233U/Th in MSR.•Both scenarios can achieve the transition, and the B&B scenario is more favorable due to its resource utilization efficiency.•These analyses can provide references for gradual deployment of the thorium-based MSRs and large-scale thorium utilization.
Extensive work has been carried out by the U.S. Department of Energy (DOE) in the development of a proposed geologic repository at Yucca Mountain (YM), Nevada, for the disposal of high-level ...radioactive waste. In support of this development and an associated license application to the U.S. Nuclear Regulatory Commission (NRC), the DOE completed an extensive performance assessment (PA) for the proposed YM repository in 2008. This presentation describes uncertainty and sensitivity analysis results for the nominal scenario class (i.e., for undisturbed conditions) obtained in the 2008 YM PA. The following topics are addressed: (i) uncertainty and sensitivity analysis procedures, (ii) drip shield and waste package failure, (iii) engineered barrier system conditions, (iv) radionuclide release results for the engineered barrier system, unsaturated zone, and saturated zone, and (v) dose to the reasonably maximally exposed individual specified in the NRC regulations for the YM repository. The present article is part of a special issue of Reliability Engineering and System Safety devoted to the 2008 YM PA; additional articles in the issue describe other aspects of the 2008 YM PA.
•We describe uncertainty and sensitivity analysis for the nominal scenario class in the 2008 YM performance assessment.•We present results for drip shield and waste package failure and engineered barrier system conditions.•We present analyses of radionuclide releases and dose to the reasonably maximally exposed individual.
This study explored the moderating and mediating influences of self-acceptance and tolerance to others in the relationship between mindfulness and subjective well-being. In total, 301 (130 males) ...university students completed the Five-Facet Mindfulness Questionnaire, Index of Well-being, Self-acceptance Questionnaire, and Tolerance Scale. The results showed that the positive link between mindfulness and subjective well-being was significantly mediated by self-acceptance only. Tolerance played a moderating role. The implications of the results for relevant research and mindfulness training were discussed.
With wearable electronics becoming increasingly fashionable, flexible energy storage devices are attracting a lot of attention. Their main component, the pliable electrodes can be categorized as ...substrate‐supported and free‐standing. Depending on their modes of deformation they can be labeled as bendable, compressible or stretchable electrodes. In article number 1600490, Ray P. S. Han and co‐workers summarize recent progress and challenges in the design and fabrication of pliable electrodes for flexible energy storage devices.
Large solar power stations are usually located in remote areas and connect to the main grid via a long transmission line. The energy storage unit is deployed locally with the solar plant to smooth ...its output. Capacities of the grid-connection transmission line and the energy storage unit have a significant impact on the utilization rate of solar energy, as well as the investment cost. This article characterizes the feasible set of capacity parameters under a given solar spillage rate and a fixed investment budget. A linear programming-based projection algorithm is proposed to obtain such a feasible set, offering valuable references for system planning and policy making.
The load-bearing dentoalveolar fibrous joint is composed of biomechanically active periodontal ligament (PDL), bone, cementum, and the synergistic entheses of PDL-bone and PDL-cementum. Physiologic ...and pathologic loads on the dentoalveolar fibrous joint prompt natural shifts in strain gradients within mineralized and fibrous tissues and trigger a cascade of biochemical events within the widened and narrowed sites of the periodontal complex. This review highlights data from in situ biomechanical simulations that provide tooth movements relative to the alveolar socket. The methods and subsequent results provide a reasonable approximation of strain-regulated biochemical events resulting in mesial mineral formation and distal resorption events within microanatomical regions at the ligament-tethered/enthesial ends. These biochemical events, including expressions of biglycan, decorin, chondroitin sulfated neuroglial 2, osteopontin, and bone sialoprotein and localization of various hypertrophic progenitors, are observed at the alkaline phosphatase–positive widened site, resulting in mineral formation and osteoid/cementoid layers. On the narrowed side, tartrate-resistant acid phosphatase regions can lead to a sequence of clastic activities resulting in resorption pits in bone and cementum. These strain-regulated biochemical and subsequently biomineralization events in the load-bearing periodontal complex are critical for maintenance of the periodontal space and overall macroscale joint biomechanics.
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