This paper presents a method to estimate the inverter lifetime so that we can predict a failure prior to it actually happening. The key contribution of this study is to link the physics of the power ...devices to a large scale system simulation within a reasonable framework of time. By configuring this technique to a real system, it can be used as a converter design tool or online lifetime estimation tool. In this paper, the presented method is applied to the grid side inverter to show its validity. A power cycling test is designed to gather the lifetime data of a selected insulated gate bipolar transistor (IGBT) module (SKM50GB123D). Die-attach solder fatigue is found out to be the dominant failure mode of this IGBT module under the designed accelerated tests. Furthermore, the crack initiation is found to be highly stress dependent while the crack propagation is almost independent with stress level. Two different damage accumulation methods are used and the estimation results are compared.
The superradiant stability of asymptotically flat
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-dimensional extremal Reissner–Nordstrom black holes under charged massive scalar perturbation is analytically studied. Recently, an analytical ...method has been proposed by the author and used to prove that five and six-dimensional extremal Reissner–Nordstrom black holes are superradiantly stable under charged massive scalar perturbation. We apply this analytical method in the
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-dimensional extremal Reissner–Nordstrom black hole case and prove that there is no black hole bomb for
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-dimensional Reissner–Nordstrom black hole under charged massive scalar perturbation and the system is superradiantly stable.
Abnormal metabolism of tumour cells is closely related to the occurrence and development of breast cancer, during which the expression of NF‐E2‐related factor 2 (Nrf2) is of great significance. ...Metastatic breast cancer is one of the most common causes of cancer death worldwide; however, the molecular mechanism underlying breast cancer metastasis remains unknown. In this study, we found that the overexpression of Nrf2 promoted proliferation and migration of breast cancers cells. Inhibition of Nrf2 and overexpression of Kelch‐like ECH‐associated protein 1 (Keap1) reduced the expression of glucose‐6‐phosphate dehydrogenase (G6PD) and transketolase of pentose phosphate pathway, and overexpression of Nrf2 and knockdown of Keap1 had opposite effects. Our results further showed that the overexpression of Nrf2 promoted the expression of G6PD and Hypoxia‐inducing factor 1α (HIF‐1α) in MCF‐7 and MDA‐MB‐231 cells. Overexpression of Nrf2 up‐regulated the expression of Notch1 via G6PD/HIF‐1α pathway. Notch signalling pathway affected the proliferation of breast cancer by affecting its downstream gene HES‐1, and regulated the migration of breast cancer cells by affecting the expression of EMT pathway. The results suggest that Nrf2 is a potential molecular target for the treatment of breast cancer and targeting Notch1 signalling pathway may provide a promising strategy for the treatment of Nrf2‐driven breast cancer metastasis.
Constructing highly planar, extended π-electron systems is an important strategy for achieving high-mobility organic semiconductors. In general, there are two synthetic strategies for achieving ...π-conjugated systems with high planarity. The conventional strategy connects neighboring aromatic rings through covalent bonds to restrict the rotation about single bonds. However, this usually requires a complex sequence of synthetic steps to achieve this target, which can be costly and labor-intensive. More recently, noncovalent through-space intramolecular interactions, which are defined here as noncovalent conformational locks, have been employed with great success to increase the planarity and rigidity of extended π-electron systems; this has become a well-known and important strategy to design and synthesize highly planar π-conjugated systems for organic electronics. This review offers a comprehensive and general summary of conjugated systems with such noncovalent conformational locks, including O···S, N···S, X···S (where X = Cl, Br, F), and H···S through-space interactions, together with analysis by density functional theory computation, X-ray diffraction, and microstructural characterization, as well as by evaluation of charge transport in organic thin-film transistors and solar cells.
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bstract
In this paper, we consider the dynamics of charge imbalance resolved negativity after a local joining quench in the 1 + 1 dimensional free complex boson CFT. In the first part, we study the ...local joining quench by applying conformal maps, obtaining analytical universal results. We first calculate the quench dynamics of charged logarithmic negativity. Then using the Fourier transformation, we obtain the charge imbalance resolved negativity. The total negativity can be recovered from the charge-resolved ones. In the second part, we test our CFT predictions against the underlying lattice model numerically. Finally, we explain our results based on the quasi-particle picture.
Hepatocellular carcinoma (HCC) is the most predominant primary malignancy in the liver. Genotoxic and genetic models have revealed that HCC cells are derived from hepatocytes, but where the critical ...region for tumor foci emergence is and how this transformation occurs are still unclear. Here, hyperpolyploidization of hepatocytes around the centrilobular (CL) region is demonstrated to be closely linked with the development of HCC cells after diethylnitrosamine treatment. We identify the CL region as a dominant lobule for accumulation of hyperpolyploid hepatocytes and preneoplastic tumor foci formation. We also demonstrate that upregulation of Aurkb plays a critical role in promoting hyperpolyploidization. Increase of AURKB phosphorylation is detected on the midbody during cytokinesis, causing abscission failure and hyperpolyploidization. Pharmacological inhibition of AURKB dramatically reduces nucleus size and tumor foci number surrounding the CL region in diethylnitrosamine-treated liver. Our work reveals an intimate molecular link between pathological hyperpolyploidy of CL hepatocytes and transformation into HCC cells.
To test various formulas and techniques for manufacturing dry-fabricated bio-film (DFBF) that exhibits physical properties advantageous to the use of the DFBF in wound dressings, a DFBF was ...fabricated by adding chitosan (Chi) and alginate (Alg) to homogenized bacterial cellulose (BC) obtained from vinegar pellicles in vinegar brewing byproducts in this study. The results revealed that the degree of oxidation in DFBF manufactured using hydrogen peroxide oxidized BC (HOBC), with 0.092% carboxyl group content, was lower than that in DFBF manufactured using periodic acid oxidized BC (POBC), but DFBF made using HOBC exhibited higher elongation, rehydration, swelling ratios, and water vapor transmission than that fabricated using POBC. A DFBF composite gel with 98.5% water content possessed appropriate fluidity for molding. After 10 min of rinsing cross-linked HOBC, 72 ppm of calcium remained in the final DFBF, which not only prevented cell toxicity but also demonstrated desirable mechanical and rehydration properties. Overall, the modified DFBF possessed a high rehydration ratio of 51.69% and could absorb and gradually release naringin by up to 80% within 24 h. This modified DFBF has the potential for exudate absorption and the controlled release of medicinal substances at the initial stage of healing when used in wound dressings.
(Release of naringin from DFBF) Display omitted
•DFBF was fabricated by adding chitosan and alginate to homogenized bacterial cellulose.•DFBF manufactured using H2O2 exhibited higher mechanical properties, hydrophilicity and WVTR.•A DFBF composite gel with 98.5% water content possessed appropriate fluidity for molding.•DFBF possessed biocompatibility and gradually release naringin by up to 80% within 24 h.•DFBF has potential for exudate absorption and controlled release of medicines in wound dressings.
The nature of marketing science is changing in a systematic, predictable, and irrevocable way. As information technology enables ubiquitous customer communication and big customer data, the ...fundamental nature of the firm's connection to the customer changes: better, more personalized service can be offered, from which service relationships are deepened, and consequently, more profitable customers grow the influence of service within the goods sector and expand the service sector in the economy. Marketing is becoming more personalized, and marketing science techniques that exploit customer heterogeneity are becoming more important. Information technology improvements also guarantee the increasing importance and usage of computationally intensive data processing and "big data." Most importantly, these trends have already lasted for more than a century, and they will become even more pronounced in the coming years as a result of the monotonic nature of technology improvement. These changes imply a transformation of marketing science in both the topics to be emphasized and the methods to be employed. Increasingly, and inevitably, all of marketing will come to resemble to a greater degree the formerly specialized area of service marketing, only with an increased emphasis on marketing analytics.
Reduced graphene oxide (rGO) has huge potential for membrane applications owing to its appropriate interlayer spacing (0.34–0.37 nm) that enables it to block salt ions as small as Na+ with high ...precision. However, fabrication of uniform rGO membranes is a great challenge because of the loss of its polar functional groups during preparation from graphene oxide (GO). Although there have been several studies on GO membranes and a few on rGO for water purification, very few attempts to understand the role of oxygen-containing functional groups in successful rGO membrane formation. The present work deals with the investigation of the key factors and functional groups that govern membrane formation. This work also utilizes the facile approach of synthesizing reduced GO by environmentally viable hydrothermal reduction. Further characterizations show that the hydroxyl and carboxyl groups are principally responsible for the formation of uniform rGO membranes. The rGO (treated at 160°C for 2 h) membrane with a small amount of unreduced GO presented shows the lowest Na+/Cl- ion permeation with the highest membrane flux, which is suggested to be a potential candidate for water desalination.
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•Examination of reduced graphene oxide (rGO) membrane formability by reduction.•Uniform rGO membranes were formed at the partial reduction stage (GO/rGO coexist).•The presence of hydroxyl and carboxyl groups assists membrane formation.•The ion permeation and water transport are manipulated by degree of reduction.
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