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"Guan, Yi"
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المغامرون الصغار : ملحمة عالمية : استكشاف الطاقة النفط
ليث ولين وزياد. المغامرون الصغار بانتظار المغامرات دوما لكن سرعان ما يجدون أنفسهم أمام قضية غامضة وشائقة بسبب اختفاء البروفيسور أديب. المتهم الرئيسي في قضية انفجار مصنع شركة إنيرجيز وسيسعون معا إلى كشف الحقيقة بالبحث عنه وإثبات براءته.
Book
Acoustic non-Hermitian skin effect from twisted winding topology
The recently discovered non-Hermitian skin effect (NHSE) manifests the breakdown of current classification of topological phases in energy-nonconservative systems, and necessitates the introduction of non-Hermitian band topology. So far, all NHSE observations are based on one type of non-Hermitian band topology, in which the complex energy spectrum winds along a closed loop. As recently characterized along a synthetic dimension on a photonic platform, non-Hermitian band topology can exhibit almost arbitrary windings in momentum space, but their actual phenomena in real physical systems remain unclear. Here, we report the experimental realization of NHSE in a one-dimensional (1D) non-reciprocal acoustic crystal. With direct acoustic measurement, we demonstrate that a twisted winding, whose topology consists of two oppositely oriented loops in contact rather than a single loop, will dramatically change the NHSE, following previous predictions of unique features such as the bipolar localization and the Bloch point for a Bloch-wave-like extended state. This work reveals previously unnoticed features of NHSE, and provides the observation of physical phenomena originating from complex non-Hermitian winding topology.
Non-Hermitian skin effect fundamentally challenges the conventional topological description of a system. Here the authors demonstrate a bipolar non-Hermitian skin effect, where bulk eigenstates localize towards two directions, in a one-dimensional non-reciprocal acoustic crystal with twisted topology.
Journal Article
Important contributions of non-fossil fuel nitrogen oxides emissions
Since the industrial revolution, it has been assumed that fossil-fuel combustions dominate increasing nitrogen oxide (NO
x
) emissions. However, it remains uncertain to the actual contribution of the non-fossil fuel NO
x
to total NO
x
emissions. Natural N isotopes of NO
3
−
in precipitation (δ
15
N
w-NO3−
) have been widely employed for tracing atmospheric NO
x
sources. Here, we compiled global δ
15
N
w-NO3−
observations to evaluate the relative importance of fossil and non-fossil fuel NO
x
emissions. We found that regional differences in human activities directly influenced spatial-temporal patterns of δ
15
N
w-NO3−
variations. Further, isotope mass-balance and bottom-up calculations suggest that the non-fossil fuel NO
x
accounts for 55 ± 7% of total NO
x
emissions, reaching up to 21.6 ± 16.6Mt yr
−1
in East Asia, 7.4 ± 5.5Mt yr
−1
in Europe, and 21.8 ± 18.5Mt yr
−1
in North America, respectively. These results reveal the importance of non-fossil fuel NO
x
emissions and provide direct evidence for making strategies on mitigating atmospheric NO
x
pollution.
This study investigates in the importance of non-fossil fuel NO
x
emissions in the surface-earth-nitrogen cycle. The study shows how changes of regional human activities directly influence δ
15
N signatures of deposited NO
x
to terrestrial environments and that emissions have largely been underestimated.
Journal Article
وثائق مكافحة كوفيد-19
بين يدي القارئ كتاب يجمع بين دفتيه الترجمة العربية لوثائق مكافحة كوفيد 19- التي أصدرتها لجنة الصحة الوطنية الصينية، ومـن بـين هذه الوثائق النسخ الست مـن آليات الوقاية مـن الالتهاب الرئوي الناجم عـن فيروس كـورونا المستجد ومكافحته، والنسخة التجريبية السابعة لآليات تـشخيص الالتـِهاب الـرئوي الناجِم عـن فـيروس كـورونا المستجد وعلاجه وغـيرها مـن الـمرفقات. وعـمل على ترجمة النـسخة الـعربية لوثائق مكافحة كـوفيد 19- الصينية فريـق ترجمة به أكـثر من عشريـن أستاذا وطالبا مـن قسم اللغة العربية بكلية اللغات الأجنبية بجامعة بكين بـالتعاون مع كلية الآداب في جامعة القاهرة والمعهد العالي للغات بتونس في جامعة قرطاج، في الفترة مـن مارس وحتى مايو 2020، قام خلالها فـريق الترجمة بترجمة قرابة 100 ألـف رمز صيني.
BOOK
Observation of an acoustic octupole topological insulator
Berry phase associated with energy bands in crystals can lead to quantised observables like quantised dipole polarizations in one-dimensional topological insulators. Recent theories have generalised the concept of quantised dipoles to multipoles, resulting in the discovery of multipole topological insulators which exhibit a hierarchy of multipole topology: a quantised octupole moment in a three-dimensional bulk induces quantised quadrupole moments on its two-dimensional surfaces, which in turn induce quantised dipole moments on one-dimensional hinges. Here, we report on the realisation of an octupole topological insulator in a three-dimensional acoustic metamaterial. We observe zero-dimensional topological corner states, one-dimensional gapped hinge states, two-dimensional gapped surface states, and three-dimensional gapped bulk states, representing the hierarchy of octupole, quadrupole and dipole moments. Conditions for forming a nontrivial octupole moment are demonstrated by comparisons with two different lattice configurations having trivial octupole moments. Our work establishes the multipole topology and its full hierarchy in three-dimensional geometries.
The concept of topological corner states in two dimensional topological insulators can be generalised to higher dimensions. Here, authors present a three dimensional acoustic metamaterial that exhibits the full hierarchy of topological multipole states including corner, hinge, surface and bulk states.
Journal Article
Two Methods for Mapping and Visualizing Associated Data on Phylogeny Using Ggtree
Ggtree is a comprehensive R package for visualizing and annotating phylogenetic trees with associated data. It can also map and visualize associated external data on phylogenies with two general methods. Method 1 allows external data to be mapped on the tree structure and used as visual characteristic in tree and data visualization. Method 2 plots the data with the tree side by side using different geometric functions after reordering the data based on the tree structure. These two methods integrate data with phylogeny for further exploration and comparison in the evolutionary biology context. Ggtree is available from http://www.bioconductor.org/packages/ggtree.
Journal Article
DNA Repair Pathways in Cancer Therapy and Resistance
DNA repair pathways are triggered to maintain genetic stability and integrity when mammalian cells are exposed to endogenous or exogenous DNA-damaging agents. The deregulation of DNA repair pathways is associated with the initiation and progression of cancer. As the primary anti-cancer therapies, ionizing radiation and chemotherapeutic agents induce cell death by directly or indirectly causing DNA damage, dysregulation of the DNA damage response may contribute to hypersensitivity or resistance of cancer cells to genotoxic agents and targeting DNA repair pathway can increase the tumor sensitivity to cancer therapies. Therefore, targeting DNA repair pathways may be a potential therapeutic approach for cancer treatment. A better understanding of the biology and the regulatory mechanisms of DNA repair pathways has the potential to facilitate the development of inhibitors of nuclear and mitochondria DNA repair pathways for enhancing anticancer effect of DNA damage-based therapy.
Journal Article
Vortex states in an acoustic Weyl crystal with a topological lattice defect
Crystalline materials can host topological lattice defects that are robust against local deformations, and such defects can interact in interesting ways with the topological features of the underlying band structure. We design and implement a three dimensional acoustic Weyl metamaterial hosting robust modes bound to a one-dimensional topological lattice defect. The modes are related to topological features of the bulk bands, and carry nonzero orbital angular momentum locked to the direction of propagation. They span a range of axial wavenumbers defined by the projections of two bulk Weyl points to a one-dimensional subspace, in a manner analogous to the formation of Fermi arc surface states. We use acoustic experiments to probe their dispersion relation, orbital angular momentum locked waveguiding, and ability to emit acoustic vortices into free space. These results point to new possibilities for creating and exploiting topological modes in three-dimensional structures through the interplay between band topology in momentum space and topological lattice defects in real space.
Here, the authors introduce a 3D Weyl metamaterial hosting modes bound to a 1D topological lattice defect. The modes carry nonzero orbital angular momentum locked to the direction of propagation, and they experimentally demonstrate the ability to emit acoustic vortices into free space.
Journal Article
Significant contributions of combustion-related sources to ammonia emissions
Atmospheric ammonia (NH
3
) and ammonium (NH
4
+
) can substantially influence air quality, ecosystems, and climate. NH
3
volatilization from fertilizers and wastes (v-NH
3
) has long been assumed to be the primary NH
3
source, but the contribution of combustion-related NH
3
(c-NH
3
, mainly fossil fuels and biomass burning) remains unconstrained. Here, we collated nitrogen isotopes of atmospheric NH
3
and NH
4
+
and established a robust method to differentiate v-NH
3
and c-NH
3
. We found that the relative contribution of the c-NH
3
in the total NH
3
emissions reached up to 40 ± 21% (6.6 ± 3.4 Tg N yr
−1
), 49 ± 16% (2.8 ± 0.9 Tg N yr
−1
), and 44 ± 19% (2.8 ± 1.3 Tg N yr
−1
) in East Asia, North America, and Europe, respectively, though its fractions and amounts in these regions generally decreased over the past decades. Given its importance, c-NH
3
emission should be considered in making emission inventories, dispersion modeling, mitigation strategies, budgeting deposition fluxes, and evaluating the ecological effects of atmospheric NH
3
loading.
By integrating nitrogen isotope systematics of ammonia emissions and transformations in the atmosphere, this study quantified the combustion-related ammonia emission and uncovered its importance for mitigating strategies of ammonia pollution.
Journal Article