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•Fatigue properties of additively manufactured (AM) AlSi10Mg are similar to castings.•Oxide-driven porosity is the most common internal defect in the AM parts.•Pores and oxide ...particle size at the part surface control fatigue life.
It is well-known that the fatigue behavior of cast aluminum alloy parts is largely determined by internal defects, particularly pores and inclusions. In this work, it is shown that such imperfections are also present in AlSi10Mg parts produced by selective laser melting, and serve as sites to initiate fatigue cracks. The effect of hatch spacing and building orientation on tensile and fatigue properties was tested. Oxide-driven pores dominate the fatigue resistance of the samples in this work. The larger oxide particles which are associated with crack initiation likely form by oxidation of metal vapor during part manufacture.
Orogenic quiescence in Earth’s middle age Tang, Ming; Chu, Xu; Hao, Jihua ...
Science (American Association for the Advancement of Science),
02/2021, Letnik:
371, Številka:
6530
Journal Article
Recenzirano
Odprti dostop
Mountain belts modulate denudation flux and hydrologic processes and are thus fundamental to nutrient cycling on Earth’s surface. We used europium anomalies in detrital zircons to track ...mountain-building processes over Earth’s history. We show that the average thickness of active continental crust varied on billion-year time scales, with the thickest crust formed in the Archean and Phanerozoic. By contrast, the Proterozoic witnessed continuously decreasing crustal thickness, leaving the continents devoid of high mountains until the end of the eon. We link this gradually diminished orogenesis to the long-lived Nuna-Rodinia supercontinent, which altered the mantle thermal structure and weakened the continental lithosphere. This prolonged orogenic quiescence may have resulted in a persistent famine in the oceans and stalled life’s evolution in Earth’s middle age.
Organic semiconductors have great potential as the active material in low-cost, large area plastic electronics, whether as light-emitting diodes (LEDs), field-effect transistors (FETs) or solar ...cells. Organic semiconducting materials retain the processability associated with polymers while maintaining good optoelectronic properties, for example, high absorption coefficients for photons in the visible, and field-effect mobilities comparable with that of amorphous silicon. The elucidation of important structure−property relationships is vital for the design of functional, high-performance organic semiconductors. In this short review, we summarize such relationships stemming from the halogenation of organic semiconductors. While it has been known in the past decade that fluorination lowers the energy levels in carbon based systems, induces stability and electron transport, less is known about the effect of the other halogens. Chlorination has recently been shown to be a viable route to n-type materials. The bandgap of conjugated compounds can also be decreased slightly by the addition of Cl, Br, and I to the aromatic core. The effect of the halogenated moieties on the packing of molecules is discussed.
Structural modulations have been recently found to cause some unusual physical properties, such as superconductivity or charge density waves; however, thus‐induced nonlinear optical properties are ...rare. We report herein two unprecedented incommensurately modulated nonlinear optical sulfides exhibiting phase matching behavior, A2SnS5 (A=Ba, Sr), with the (3+1)D superspace groups P21212(00γ)00s or P21(α0γ)0, featuring different modulations of the Sn2S7∞ belts. Remarkably, Ba2SnS5 exhibits an excellent second harmonic generation (SHG) of 1.1 times that of the benchmark compound AgGaS2 at 1570 nm and a very large laser‐induced damage threshold (LIDT) of 8×AgGaS2. Theoretical studies revealed that the structural modulations increase the distortions of the Sn/S building units by about 44 or 25 % in A2SnS5 (A=Ba, Sr), respectively, and enhance significantly the SHG compared with α‐Ba2SnSe5 without modulation. Besides, despite the smaller Eg, the A2SnS5 samples exhibit higher LIDTs owing to their smaller thermal expansion anisotropies (Ba2SnS5 (1.51)<Sr2SnS5 (2.08)<AgGaS2 (2.97)).
Two incommensurately modulated nonlinear optical sulfides, Ba2SnS5 and Sr2SnS5, exhibit phase matching behavior and large laser‐induced damage thresholds. The second harmonic generation of Ba2SnS5 at 1570 nm is 1.1‐fold stronger than that of AgGaS2 as it benefits from the positional and occupational modulations.
The tension biology of wound healing Harn, Hans I‐Chen; Ogawa, Rei; Hsu, Chao‐Kai ...
Experimental dermatology,
April 2019, Letnik:
28, Številka:
4
Journal Article
Recenzirano
Odprti dostop
Following skin wounding, the healing outcome can be: regeneration, repair with normal scar tissue, repair with hypertrophic scar tissue or the formation of keloids. The role of chemical factors in ...wound healing has been extensively explored, and while there is evidence suggesting the role of mechanical forces, its influence is much less well defined. Here, we provide a brief review on the recent progress of the role of mechanical force in skin wound healing by comparing laboratory mice, African spiny mice, fetal wound healing and adult scar keloid formation. A comparison across different species may provide insight into key regulators. Interestingly, some findings suggest tension can induce an immune response, and this provides a new link between mechanical and chemical forces. Clinically, manipulating skin tension has been demonstrated to be effective for scar prevention and treatment, but not for tissue regeneration. Utilising this knowledge, specialists may modulate regulatory factors and develop therapeutic strategies to reduce scar formation and promote regeneration.
The efficacy of a simple, electrically small, low-profile, Huygens source antenna that radiates in its broadside direction is demonstrated numerically and experimentally. First, two types of ...electrically small, near-field resonant parasitic (NFRP) antennas are introduced and their individual radiation performance characteristics are discussed. The electric one is based on a modified Egyptian axe dipole NFRP element; the magnetic one is based on a capacitively loaded loop NFRP element. In both cases, the driven element is a simple coax-fed dipole antenna, and there is no ground plane. By organically combining these two elements, Huygens source antennas are obtained. A forward propagating demonstrator version was fabricated and tested. The experimental results are in good agreement with their analytical and simulated values. This low profile, ~0.05λ 0 , and electrically small, ka = 0.645, prototype yielded a peak realized gain of 2.03 dBi in the broadside direction with a front-to-back ratio of 16.92 dB. A backward radiating version is also obtained; its simulated current distribution behavior is compared with that of the forward version to illustrate the design principles.
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On a global scale, the epidemic of the novel coronavirus (NCOV-2019) has become a major issue that is seriously harming human health and impairing the environment's quality. The ...current study examines the association between air pollution and NCOV-2019 in China, where cases of NCOV-2019 are correlated with deaths in public databases with data on air pollution tracked at multiple locations in different provinces of China. A negative binomial regression (NBR) model was applied to examine the difference between the number of people infected with NCOV-2019 and the number of deaths in China. The findings show that, after population density regulation, there is a positive connection between air pollutants concentration (particularly nitrogen dioxide) and the number of NCOV-2019 cases and deaths. Furthermore, PM2.5 is the key cause of NCOV-2019 cases and deaths in China. The results indicate that a 1% increase in the average of PM2.5 was correlated with an increase of 11.67 % in NCOV-2019 cases and a rise of 18 % in NCOV-2019 deaths. We concluded that a slight rise in air pollution has caused the number of NCOV-2019 cases and deaths to increase dramatically. This research provides a basis for future policies affected by this pandemic in terms of health and pollution.
Graph neural networks (GNNs), as a branch of deep learning in non-Euclidean space, perform particularly well in various tasks that process graph structure data. With the rapid accumulation of ...biological network data, GNNs have also become an important tool in bioinformatics. In this research, a systematic survey of GNNs and their advances in bioinformatics is presented from multiple perspectives. We first introduce some commonly used GNN models and their basic principles. Then, three representative tasks are proposed based on the three levels of structural information that can be learned by GNNs: node classification, link prediction, and graph generation. Meanwhile, according to the specific applications for various omics data, we categorize and discuss the related studies in three aspects: disease prediction, drug discovery, and biomedical imaging. Based on the analysis, we provide an outlook on the shortcomings of current studies and point out their developing prospect. Although GNNs have achieved excellent results in many biological tasks at present, they still face challenges in terms of low-quality data processing, methodology, and interpretability and have a long road ahead. We believe that GNNs are potentially an excellent method that solves various biological problems in bioinformatics research.
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