Microwave Absorbing Performance of RE-Fe Based Alloys Liu, Xing; Pan, Shunkang; Cheng, Lichun ...
Journal of Wuhan University of Technology. Materials science edition,
06/2015, Letnik:
30, Številka:
3
Journal Article
Recenzirano
REI3Fes4Cr3（RE=Ce, Pr, Tb, Er） and Pr13_XFes4Cr3Ti（x=0, 2, 4, 6） alloy powders were prepared by are smelting method and high energy ball milling technique. The phase structure and the morphology of ...the alloy powders were investigated by X-ray diffraction （XRD） and scanning electron microscopy （SEM）, and their microwave absorbing properties were determined by a vector network analyzer. The results show that the alloys with light rare earths （Ce, Pr） have good low frequency absorbing property and those with heavy rare earths （Tb, Er） exhibit an improved high frequency absorbing property. The minimum refleetivity at the absorbing peak frequency of RE,FeuCr3（RE=Ce, Pr, Tb, Er） are -9.49 dB at 5.76 GHz, -22.38 dB at 7.92 GHz, -18.52 dB at 11.68 GHz and -17.59 dB at 10.24 GHz, respectively. The absorbing bandwidth under -10 dB of the Pr13FesaCr3 powder was widened from 1.91 GI-Iz to 3.89 GHz by adding 2% Ti, but the reflectivity of the alloy was increased from -22.38 dB to -14.91 riB.
•A coaxial mechanical motion rectifier with function of increasing transmission ratio.•A variable inertia flywheel for extending overrunning phase.•Dynamics modeling of mechanical motion rectifier ...considering overrunning phase.•Establishment of angular velocity of the generator with variable inertia flywheel.•Max efficiency of 51.54% in lab and max power of 3.35 W in ocean.
The wave energy harvester has been employed to power marine devices. For the wave energy harvester based on mechanical motion rectifier, the output power and efficiency are limited due to low inertia-damping ratio and perpendicular motion transformation. A coaxial mechanical motion rectifier with the function of increasing transmission ratio is designed based on a planetary gear train and four one-way clutches, and the input and output shafts are arranged coaxially. A variable inertia flywheel is incorporated in the wave energy harvester to extend the overrunning phase by slowing down the velocity attenuation of the generator. The wheel in variable inertia flywheel is reduced to four cantilever sliders to decrease the starting torque. The dynamics model of the wave energy harvester considering the meshing and overrunning phases is investigated due to the introduction of variable inertia flywheel. The input force and output voltage are simulated with sinusoidal displacement input after obtaining the angular velocity of generator with variable inertia flywheel. A maximum efficiency of 51.54% and average output power of 1.17 W on Instron machine are achieved, while a maximum output power of 3.35 W in ocean tests is obtained. The experiments verify that the design of coaxial mechanical motion rectifier and variable inertia flywheel is beneficial to improving the output power and efficiency.
As a kind of photoluminescent material, CuI complexes have many advantages such as adjustable emission, variable structures, and low cost, attracting attention in many fields. In this work, two novel ...two‐coordinate CuI‐N‐heterocyclic carbene complexes were synthesized, and they exhibit unique dual emission properties, fluorescence and phosphorescence. The crystal structure, packing mode, and photophysical properties under different conditions were systematically studied, proving the emissive mechanism to be the locally excited state of the carbazole group. Based on this mechanism, ultralong room‐temperature phosphorescence (RTP) with a lifetime of 140 ms is achieved by selective deuteration of the carbazole group. These results deepen the understanding of the luminescence mechanism and design strategy for two‐coordinate CuI complexes, and prove their potential in applications as ultralong RTP materials.
Two CuI‐N‐heterocyclic carbene complexes were designed and they demonstrated dual emission properties. A series of spectral, crystal, and theoretical studies proved the novel luminescence nature of the locally excited state in the complexes. Ultralong room‐temperature phosphorescence emission of 140 ms and a total photoluminescence quantum yield of 36.3 % were achieved by selective deuteration of the carbazole group.
Circadian regulation is critically important in maintaining metabolic and physiological homeostasis. However, little is known about the possible influence of the clock on physiological abnormalities ...occurring under pathological conditions. Here, we report the discovery that hypoxia, a condition that causes catastrophic bodily damage, is gated by the circadian clock in vivo. Hypoxia signals conversely regulate the clock by slowing the circadian cycle and dampening the amplitude of oscillations in a dose-dependent manner. ChIP-seq analyses of hypoxia-inducible factor HIF1A and the core clock component BMAL1 revealed crosstalk between hypoxia and the clock at the genome level. Further, severe consequences caused by acute hypoxia, such as those that occur with heart attacks, were correlated with defects in circadian rhythms. We propose that the clock plays functions in fine-tuning hypoxic responses under pathophysiological conditions. We argue that the clock can, and likely should, be exploited therapeutically to reduce the severity of fatal hypoxia-related diseases.
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•The hypoxic response is gated by the circadian clock in vivo•HIF1A is the regulatory node that connects hypoxia signaling with the circadian clock•ChIP-seq analyses demonstrated that HIF1A and BMAL1 engage in synergistic crosstalk•A heart attack model emphasizes the pathological significance of this crosstalk
Wu et al. reveal that the hypoxic response is gated by the circadian clock, and ChIP-seq analyses of HIF1A and BMAL1 show that this hypoxia-clock reciprocal regulation occurs at the genomic level. In a mouse model of heart attack, the circadian clock protects the heart from hypoxia-induced cell death.
In this paper, Morse theory is used to show the existence of nontrivial solutions to the nonlocal p-Kirchhoff-type quasilinear elliptic equation M(∫Ω|∇u|pdx)p−1(−Δpu)=f(x,u) in a smooth bounded ...domain Ω⊂RN with Dirichlet boundary condition.
The friction stir lap welding (FSLW) was employed to join the dissimilar 5052 Al alloy and DP590 steel. The intermetallic compound (IMC) formation area and thickness increased linearly with ...increasing rotation speeds at 300 mm/min welding speed. Microvoid and gap defects existed on low-rotational-speed-produced lap interfaces, disappearing with increasing rotation speeds. However, cavities defects neighbouring the large-sized steel fragment appeared in the stir zone of the Al matrix with rotation speeds higher than 750 rpm. The negative influences from the Al-rich IMCs layer exceeding 1.5 µm thick and the aggravating internal cavities defects significantly reduced the joint strength. Correspondingly, the fracture mode of the friction stir lap welded 5052 alloy and DP590 steel was converted from the semi-brittle fracture into the full-brittle fracture. The maximum tensile shear force of 4.52 kN reached 75.2% of the Al 5052 base metal, obtained at the rotation speed of 750 rpm. However, from the combined perspective of integral bearing load capacity and local shear strength, the rotation speed of 500 rpm was recommended to achieve sound FSLW joints of Al5052/DP590.
•Well-formed dissimilar Al5052/DP590 joints were obtained by friction stir lap welding (FSLW).•IMCs layer distribution was correlated to interfacial strength and fractured behaviour.•Material flow characterization and IMCs formation sequence were discussed.•IMCs layer with thickness exceeding 1.5 µm was found to deteriorate the FLSWed Al 5052/DP590 joint significantly.
The purpose of this study is to identify medications with potentially beneficial effects on decreasing mortality in patients with acute kidney injury (AKI) while in the intensive care unit (ICU). We ...used logistic regression to investigate associations between medications received and ICU mortality in patients with AKI in the MIMIC III database. Drugs associated with reduced mortality were then validated using the eICU database. Propensity score matching (PSM) was used for matching the patients' baseline severity of illness followed by a chi-square test to calculate the significance of drug use and mortality. Finally, we examined gene expression signatures to explore the drug's molecular mechanism on AKI. While several drugs demonstrated potential beneficial effects on reducing mortality, most were used for potentially fatal illnesses (e.g. antibiotics, cardiac medications). One exception was found, ondansetron, a drug without previously identified life-saving effects, has correlation with lower mortality among AKI patients. This association was confirmed in a subsequent analysis using the eICU database. Based on the comparison of gene expression signatures, the presumed therapeutic effect of ondansetron may be elicited through the NF-KB pathway and JAK-STAT pathway. Our findings provide real-world evidence to support clinical trials of ondansetron for treatment of AKI.
Due to the time-varying and space-varying characteristics of the underwater acoustic channel, the communication process may be seriously disturbed. Thus, the underwater acoustic communication system ...is facing the challenges of alleviating interference and improving communication quality and communication efficiency through adaptive modulation. In order to select the optimal modulation mode adaptively and maximize the system throughput ensuring that the bit error rate (BER) meets the transmission requirements, this paper introduces deep reinforcement learning (DRL) into orthogonal frequency division multiplexing acoustic communication system. The adaptive modulation is mapped into a Markov decision process with unknown state transition probability. Thereby, the underwater communication channel environment is regarded as the state of DRL, and the modulation mode is regarded as action. The system returns channel state information (CSI) and signal–noise ratio in every time slot through the feedback link. Because the Deep Q-Network optimizes in the changing state space of each time slot, it is suitable for a variety of different CSI. Finally, simulations in different underwater environments (SWellEx-96) show that the proposed adaptive modulation scheme can obtain lower BER and improve the system throughput effectively.
Under appropriate assumptions on the N(Ω)-function, the De Giorgi process is presented by the tools recently developed in Musielak–Orlicz–Sobolev space to prove the Hölder continuity of fully ...nonlinear elliptic problems. As the applications, the Hölder continuity of the minimizers for a class of the energy functionals in Musielak–Orlicz–Sobolev spaces is proved; and furthermore, the local Hölder continuity of the weak solutions for a class of fully nonlinear elliptic equations is provided.
Critical point theory is used to show the existence of weak solutions to a quasilinear elliptic differential equation under the functional framework of the Musielak–Sobolev spaces in a bounded smooth ...domain with Dirichlet boundary condition.
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