Experimental Investigation and Optimization Design of Multi-Support Pipeline System

The design of aircraft hydraulic pipeline system is limited by many factors,such as the integrity of aviation structure or narrow installation space,so the limited clamp support position should be considered.This paper studied the frequency adjustment and dynamic responses reduction of the multi-support pipeline system through experiment and numerical simulation.To avoid the resonance of pipeline system,we proposed two different optimization programs,one was to avoid aero-engine working range,and another was to avoid aircraft hydraulic pump pulsation range.An optimization method was introduced in this paper to obtain the optimal clamp position.The experiments were introduced to validate the optimization results,and the theoretical optimization results can agree well with the test.With regard to avoiding the aero-engine vibration frequency,the test results revealed that the first natural frequency was far from the aero-engine vibration frequency.And the dynamic frequency sweep results showed that no resonance occurred on the pipeline in the engine vibration frequency range after optimization.Additionally,with regard to avoiding the pump vibration frequency,the test results revealed that natural frequencies have been adjusted and far from the pump vibration frequency.And the dynamic frequency sweep results showed that pipeline under optimal clamp position cannot lead to resonance.The sensitivity analysis results revealed the changing relationships between different clamp position and natural frequency.This study can provide helpful guidance on the analysis and design of practical aircraft pipeline.

Recent advances in wave energy converters based on nonlinear stiffness mechanisms

Wave energy is one of the most abundant renewable clean energy sources,and has been widely studied because of its advantages of continuity and low seasonal variation.However,its low capture efficiency and narrow capture frequency bandwidth are still technical bottlenecks that restrict the commercial application of wave energy converters(WECs).In recent years,using a nonlinear stiffness mechanism(NSM)for passive control has provided a new way to solve these technical bottlenecks.This literature review focuses on the research performed on the use of nonlinear mechanisms in wave energy device utilization,including the conceptual design of a mechanism,hydrodynamic models,dynamic characteristics,response mechanisms,and some examples of experimental verification.Finally,future research directions are discussed and recommended.

Isolated atomic catalysts encapsulated in MOF for ultrafast water pollutant treatment

Atomic noble metals stand as one of the most advanced catalysts because of their unique properties and interaction with the reactants.However,due to their high activity,noble atomic catalysts tend to aggregate and deactivate in practical application.Moreover,supports aimed to disperse these atomic catalysts often suffer from weak confinement and poor porosity,thus limited the catalytic efficiency of noble atoms.Here,we report the facile encapsulation of atomic noble catalyst in cheap cerous metal-organic framework(Ce-MOF)crystals to create a robust catalyst that could deliver high catalytic performance for the reduction of 4-nitrophenol without decay in long-term cycling test.Specifically,Au atoms encapsulated in Ce-MOF exhibited ultrahigh turnover frequency(TOF)of 131 min−1 for the reduction of 4-nitrophenol in minutes,consuming only 10%precious metals compared with state-of-the-art catalysts operated under same condition.

SARS-CoV-2 Omicron:a new challenge for pandemic and vaccine

In a recent article published in Nature,Shuai et al.demonstrated a significantly reduced replication capacity and diminished pathogenicity of SARS-CoV-2 Omicron,the latest variant of concern(VOC),mainly due to the impaired Spike protein(S protein)cleavage,reduced efficiency in utilizing co-factor TMPRSS2.1 The replication of Omicron was attenuated in both Calu3 and Caco2 cells.1 The mechanistic studies showed that Omicron utilized the TMPRSS2 receptor less efficiently compared to other VOC strains.Omicron replication was also significantly attenuated in both upper and lower airways of infected K18-hACE2 mice compared to Delta or early HKU-001a(including D614)strains.Moreover,Omicron infection resulted in minimal weight loss and death.To sum up,they demonstrated a significantly reduced viral replication and pathogenesis of Omicron,accompanied with a much lower inflammation effect(Fig.1).

SARS-CoV-2 Omicron strain exhibits potent capabilities for immune evasion and viral entrance

Dear Editor,Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)Omicron strain(as Rnown as B.1.1.529)was identified in Botswana and South Africa in early November 2021 and was later defined as a new variant of concern(VOC)by the World Health Organization on November 26,2021.1,2 To date,the con firmed cases of Omicro n have been reported in more than 38 countries,and the number of cases appears to be rapidly in creasing.SARS-CoV-2 Omicron could give rise to the fourth wave of the COVID-19 epidemic spreading around the world,following the D614G,Beta/Gamma,and Delta VOCs.

Synthesis of N-Heterocyclic Carbine Silver(Ⅰ)and Palladium(Ⅱ)Complexes with Acylated Piperazine Linker and Catalytic Activity in Three Types of C-C Coupling Reactions

Main observation and conclusion Two bis-imidazolium salts LH_(2)·Cl_(2) and LH_(2)·(PF_(6))_(2) with acylated piperazine linker and two N-heterocyclic carbene(NHC)silver(Ⅰ)and palladium(Ⅱ)complexes[L_(2)Ag_(2)](PF_(6))_(2)(1)and[L_(2)Pd_(2)Cl_(4)](2)were prepared.The crystal structures of LH_(2)·Cl_(2) and 1 were confirmed by X-ray analysis.In 1,one 26-membered macrometallocycle was generated through two silver(Ⅰ)ions and two bidentate ligands L.The catalytic activity of 2 was investigated in Sonogashira,Heck-Mizoroki and Suzuki-Miyaura reactions.The results displayed that these C-C coupling reactions can be smoothly carried out under the catalysis of 2.

Improvement of a SARS-CoV-2 vaccine by enhancing the conjugation efficiency of the immunogen to self-assembled nanoparticles

To the Editor:Coronavirus disease 2019(COVID-19)has become a worldwide public health emergency,threatening public health and global stability[1].The development of a safe and effective vaccine is urgently needed to control the pandemic.Generally,nanoparticle(NP)vaccines can generate a more potent immune response than mRNA vaccines[2].

Infection of wild-type mice by SARS-CoV-2 B.1.351 variant indicates a possible novel cross-species transmission route

COVID-19 is identified as a zoonotic disease caused by SARS-CoV-2,which also can cross・transmit to many animals but not mice.Genetic modifications of SARS-CoV-2 or mice enable the mice susceptible to viral infection.Although neither is the natural situation,they are currently utilized to establish mouse infection models.Here we report a direct contact transmission of SARS-CoV-2 variant B.1.351 in wild-type mice.The SARS-CoV-2(B.1.351)re plicated efficiently and induced significant pathological changes in lungs and tracheas,accompanied by elevated proinflammatory cytokines in the lungs and sera.Mechanistically,the receptor-binding domain(RBD)of SARS-CoV-2(B.1.351)spike protein turned to a high binding affinity to mouse angiotensin-converting enzyme 2(mACE2),allowing the mice highly susceptible to SARS-CoV-2(B.1.351)infection.Our work suggests that SARS-CoV-2(B.1.351)expands the host range and therefore increases its transmission route without adapted mutation.As the wild house mice live with human populations quite closely,this possible transmission route could be potentially risky.In addition,because SARS-CoV-2(B.1.351)is one of the major epidemic strains and the mACE2 in laboratory-used mice is naturally expressed and regulated,the SARS-CoV-2(B.1.351)/mice could be a much convenient animal model system to study COVID-19 pathogenesis and evaluate antiviral inhibitors and vaccines.

USP10 regulates B cell response to SARS-CoV-2 or HIV-1 nanoparticle vaccines through deubiquitinating AID

Activation-induced cytidine deaminase(AID)initiates class-switch recombination and somatic hypermutation(SHM)in antibody genes.Protein expression and activity are tightly controlled by various mechanisms.However,it remains unknown whether a signal from the extracellular environment directly affects the AID activity in the nucleus where it works.Here,we demonstrated that a deubiquitinase USP10,which specifically stabilizes nuclear AID protein,can translocate into the nucleus after AKT-mediated phosphorylation at its T674 within the NLS domain.Interestingly,the signals from BCR and TLR1/2 synergistically promoted this phosphorylation.The deficiency of USP10 in B cells significantly decreased AID protein levels,subsequently reducing neutralizing antibody production after immunization with severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)or human immunodeficiency virus type 1(HIV-1)nanoparticle vaccines.Collectively,we demonstrated that USP10 functions as an integrator for both BCR and TLR signals and directly regulates nuclear AID activity.Its manipulation could be used for the development of vaccines and adjuvants.

Parametric study on power capture performance of an adaptive bistable point absorber wave energy converter in irregular waves

The power capture performance of an adaptive bistable point absorber wave energy converter(WEC)in irregular waves is investigated in this paper.Based on the linear potential flow theory and Cummins equations,the equation of motion for the WEC is established in time domain.Then a parametric study is performed on the power capture performance of the WEC by considering the influences of different wave and system parameters such as the spring combination parameter,the stiffness of auxiliary springs and main springs,the original length value of the main spring,damping coefficient of the PTO systems and the significant wave height.The results show that in an irregular wave,each parameter will have a certain impact on the performance of the device.Appropriate device parameters need to be selected according to actual environmental parameters to ensure that the adaptive bistable WEC has better power capture performance than its linear and conventional bistable counterparts.