Measured dynamic load distribution within the in situ axlebox bearing of high-speed trains under polygonal wheel–rail excitation

The dynamic load distribution within in-service axlebox bearings of high-speed trains is crucial for the fatigue reliability assessment and forward design of axlebox bearings. This paper presents an in situ measurement of the dynamic load distribution in the four rows of two axlebox bearings on a bogie wheelset of a high-speed train under polygonal wheel–rail excitation. The measurement employed an improved strain-based method to measure the dynamic radial load distribution of roller bearings. The four rows of two axlebox bearings on a wheelset exhibited different ranges of loaded zones and different means of distributed loads. Besides, the mean value and standard deviation of measured roller–raceway contact loads showed non-monotonic variations with the frequency of wheel–rail excitation. The fatigue life of the four bearing rows under polygonal wheel–rail excitation was quantitatively predicted by compiling the measured roller–raceway contact load spectra of the most loaded position and considering the load spectra as input.

β-Ga_2O_3 thin film grown on sapphire substrate by plasmaassisted molecular beam epitaxy

Monoclinic gallium oxide(Ga_2O_3) has been grown on(0001) sapphire(Al_2O_3) substrate by plasma-assisted molecular beam epitaxy(PA-MBE). The epitaxial relationship has been confirmed to be [010]( 2ˉ01) β-Ga_2O_3||[ 011ˉ0](0001)Al_2O_3 via in-situ reflection high energy electron diffraction(RHEED) monitoring and ex-situ X-ray diffraction(XRD) measurement. Crystalline quality is improved and surface becomes flatter with increasing growth temperature, with a best full width at half maximum(FWHM) of XRD ω-rocking curve of( 2ˉ01) plane and root mean square(RMS) roughness of 0.68° and 2.04 nm for the sample grown at 730 °C,respectively. Room temperature cathodoluminescence measurement shows an emission at ～417 nm, which is most likely originated from recombination of donor–acceptor pair(DAP).

CdS/LaFeO_(3) heterojunctions with improved optical properties for visible-light catalytic applications

Construction of heterojunctions is a normal and effective strategy to improve the photocatalytic performances of semiconductors,through which both the lifetime and the redox ability of electrons/holes can be improved,as co mpared to the respective component.On this basis,we constructed Z-scheme CdS/LaFeO_(3) heterojunctions(CdS/LFO),by in-situ growing different amounts of CdS on the surface of LaFeO_(3),for photocatalytic degradation of tetracycline hydrochloride(TC)in aqueous solution at room temperature.The crystal structure,surface morphology and optoelectronic properties of the COS/LFO heterojunctions were systemically characterized to correlate the reaction activity.Photocatalytic tests indicate that the CdS/LFO heterojunctions exhibit promising activity for TC degradation under visible light irradiation(λ≥420 nm),with 85%TC conversion obtained at reaction time of 45 min,which is 3.4 and 1.9 times higher than that of CdS and LaFeO_(3).The CdS/LFO heterojunctions are also stable in the reaction and can be reused for four cycles with no appreciable activity loss.The applicability of CdS/LFO to photocatalytic degradation of organic dyes,as well as the reaction mechanism,was also explored.

gp120-derived amyloidogenic peptides form amyloid fibrils that increase HIV-1 infectivity

Apart from mediating viral entry,the function of the free HIV-1 envelope protein(gp120)has yet to be elucidated.Our group previously showed that EP2 derived from oneβ-strand in gp120 can form amyloid fibrils that increase HIV-1 infectivity.Importantly,gp120 contains~30β-strands.We examined whether gp120 might serve as a precursor protein for the proteolytic release of amyloidogenic fragments that form amyloid fibrils,thereby promoting viral infection.Peptide array scanning,enzyme degradation assays,and viral infection experiments in vitro confirmed that manyβ-stranded peptides derived from gp120 can indeed form amyloid fibrils that increase HIV-1 infectivity.These gp120-derived amyloidogenic peptides,or GAPs,which were confirmed to form amyloid fibrils,were termed gp120-derived enhancers of viral infection(GEVIs).GEVIs specifically capture HIV-1 virions and promote their attachment to target cells,thereby increasing HIV-1 infectivity.Different GAPs can cross-interact to form heterogeneous fibrils that retain the ability to increase HIV-1 infectivity.GEVIs even suppressed the antiviral activity of a panel of antiretroviral agents.Notably,endogenous GAPs and GEVIs were found in the lymphatic fluid,lymph nodes,and cerebrospinal fluid(CSF)of AIDS patients in vivo.Overall,gp120-derived amyloid fibrils might play a crucial role in the process of HIV-1 infectivity and thus represent novel targets for anti-HIV therapeutics.

Autonomous Chemistry Enabling Environment-Adaptive Electrochemical Energy Storage Devices

Next-generation electronics that are fused into the human body can play a key role in future intelligent communication,smart healthcare,and human enhancement applications.As a promising energy supply component for smart biointegrated electronics,environment-adaptive electrochemical energy storage(EES)devices with complementary adaptability and functions have garnered huge interest in the past decade.Owing to the advancements in autonomous chemistry,which regulate the constitutional dynamic networks in materials,EES devices have witnessed higher freedom of autonomous adaptability in terms of mechano-adaptable,biocompatibility,and stimuli-response properties for biointegrated and smart applications.In this mini-review,we summarize the recent progress in emerging environmentadaptive EES devices enabled by the constitutional dynamic network of mechanical adaptable materials,biocompatible materials,and stimuli-responsive supramolecular polymer materials.Finally,the challenges and perspectives of autonomous chemistry on the environment-adaptive EES devices are discussed.

Decimal Solvent-Based High-Entropy Electrolyte Enabling the Extended Survival Temperature of Lithium-Ion Batteries to−130°C

Freezing and crystallization of commercial ethylene carbonate-based binary electrolytes,leading to irreversible damage to lithium-ion batteries(LIBs),remain a significant challenge for the survival of energy storage devices at extremely low temperatures(<−40°C).Herein,a decimal solvent-based high-entropy electrolyte is developed with an unprecedented low freezing point of−130°C to significantly extend the service temperature range of LIBs,far superior to−30°C of the commercial counterpart.Distinguished from conventional electrolytes,this molecularly disordered solvent mixture greatly suppresses the freezing crystallization of electrolytes,providing good protection for LIBs from possible mechanical damage at extremely low temperatures.Benefiting from this,our high-entropy electrolyte exhibits extraordinarily high ionic conductivity of 0.62 mS·cm−1 at−60°C,several orders of magnitude higher than the frozen commercial electrolytes.Impressively,LIBs utilizing decimal electrolytes can be charged and discharged even at an ultra-low temperature of−60°C,maintaining high capacity retention(∼80%at−40°C)as well as remarkable rate capability.This study provides design strategies of low-temperature electrolytes to extend the service temperature range of LIBs,creating a new avenue for improving the survival and operation of various energy storage systems under extreme environmental conditions.

Association of apolipoprotein E epsilon 4 and cognitive impairment in adults living with human immunodeficiency virus: a meta-analysis

Background: It is controversial whether the apolipoprotein E epsilon 4 allele (APOE ε4) is a risk gene for human immunodeficiency virus (HIV)-related neurocognitive impairment. This meta-analysis aimed to summarize evidence of the associations betweenAPOE ε4 and cognitive impairment in people living with HIV (PLWH).Methods: Our study conducted a systematic literature search of PubMed, Web of Science, Embase, Google Scholar, and ProQuest for studies published before April 11, 2022 that evaluated associations betweenAPOE ε4 and cognitive impairment in adult PLWH (aged ≥18 years). We calculated pooled odds ratios (ORs) of global cognitive impairment and 95% confidence intervals (CIs) and standardized mean differences (SMDs) for specific cognitive domains betweenAPOE ε4 carriers and non-carriers. Subgroup meta-analyses were used to evaluate the result profiles across different categorical variables.Results: Twenty studies met the inclusion criteria, including 19 that evaluated global cognitive impairment.APOE ε4 was significantly associated with global cognitive impairment in PLWH (OR = 1.36, 95% CI = [1.05, 1.78], number of estimates [k] = 19,P = 0.02, random effects). Subgroup meta-analysis based percentage of females showed evident intergroup differences in global cognitive performance between ε4 carriers and non-carriers (P = 0.015).APOE ε4 carriers had lower cognitive test scores than non-carriers in all seven cognitive domains, including fluency (SMD = -0.51, 95% CI = [-0.76, -0.25],P < 0.001,k = 4,I^(2)= 0%), learning (SMD = -0.52, 95% CI = [-0.75, -0.28],P < 0.001,k = 5,I^(2) = 0%), executive function (SMD = -0.41, 95% CI= [-0.59, -0.23],P < 0.001,k= 8,I^(2)= 0%), memory (SMD=-0.41, 95% CI= [-0.61, -0.20],P < 0.001,k= 10,I^(2)= 36%), attention/working memory (SMD=-0.34, 95% CI= [-0.54, -0.14],P= 0.001,k= 6,I^(2)= 0%), speed of information processing (SMD = -0.34, 95% CI = [-0.53, -0.16],P < 0.001,k = 8,I^(2) = 0%), and motor function (SMD = -0.19, 95% CI = [-0.38, -0.01],P = 0.04,k = 7,I^(2) = 0%).Conclusions: Our meta-analysis provides significant evidence thatAPOE ε4 is a risk genotype for HIV-associated cognitive impairment, especially in cognitive domains of fluency, learning, executive function, and memory. Moreover, the impairment is sex specific.Meta analysis registration: PROSPERO, CRD 42021257775.

Observation of magnetic droplets in magnetic tunnel junctions

Magnetic droplets,a class of highly nonlinear magnetodynamic solitons,can be nucleated and stabilized in nanocontact spintorque nano-oscillators.Here we experimentally demonstrate magnetic droplets in magnetic tunnel junctions(MTJs).The droplet nucleation is accompanied by power enhancement compared with its ferromagnetic resonance modes.The nucleation and stabilization of droplets are ascribed to the double-Co Fe B free-layer structure in the all-perpendicular MTJ,which provides a low Zhang-Li torque and a high pinning field.Our results enable better electrical sensitivity in fundamental studies of droplets and show that the droplets can be utilized in MTJ-based applications and materials science.

Infrared stimulated emission with an ultralow threshold from low-dislocation-density InN films grown on a vicinal GaN substrate

Near-infrared stimulated emission from a high-quality InN layer under optical pumping was observed with a threshold excitation power density of 0.3 and 4 kW cm^(−2) at T=8 and 77 K,respectively.To achieve such a low threshold power density,vicinal GaN substrates were used to reduce the edge-component threading dislocation(ETD)density of the InN film.Cross-sectional transmission electron microscopy images reveal that the annihilation of ETDs can be divided into two steps,and the ETD density can be reduced to approximately 5×10^(8) cm^(−2) near the surface of the 5-μm-thick film.The well-resolved phonon replica of the band-to-band emission in the photoluminescence spectra at 9 K confirm the high quality of the InN film.As a result,the feasibility of InN-based photonic structures and the underlying physics of their growth and emission properties are demonstrated.