Estimation of free core nutation parameters and availability of computing options

The Earth’s Free Core Nutation(FCN) causes Earth tides and forced nutation with frequencies close to the FCN that exhibit resonance effects.High-precision superconducting gravimeter(SG) and very long baseline interferometry(VLBI) provide good observation techniques for detecting the FCN parameters.However,some choices in data processing and solution procedures increase the uncertainty of the FCN parameters.In this study,we analyzed the differences and the effectiveness of weight function and ocean tide corrections in the FCN parameter detection using synthetic data,SG data from thirty-one stations,and the 10 celestial pole offset(CPO) series.The results show that significant discrepancies are caused by different computing options for a single SG station.The stacking method,which results in a variation of0.24-5 sidereal days(SDs) in the FCN period(T) and 10^(3)-10^(4) in the quality factor(Q) due to the selection of the weighting function and the ocean tide model(OTM),can effectively suppress this influence.The statistical analysis results of synthetic data shows that although different weight choices,while adjusting the proportion of diurnal tidal waves involved,do not significantly improve the accuracy of fitted FCN parameters from gravity observations.The study evaluated a series of OTMs using the loading correction efficiency.The fitting of FCN parameters can be improved by selecting the mean of appropriate OTMs based on the evaluation results.Through the estimation of the FCN parameters based on the forced nutation,it was found that the weight function P_(1) is more suitable than others,and different CPO series(after 2009) resulted in a difference of 0.4 SDs in the T and of 103 in the Q.We estimated the FCN parameters for SG(T=430.4±1.5 SDs and Q=1.52×10^(4)±2.5×10^(3)) and for VLBI(T=429.8±0.7 SDs,Q=1.88×10^(4)±2.1×10^(3)).

Similarity-based laboratory study of CO_(2) huff-n-puff in tight conglomerate cores

Tight conglomerate reservoirs are featured with extremely low permeability,strong heterogeneity and poor water injectivity.CO_(2) huff-n-puff has been considered a promising candidate to enhance oil recovery in tight reservoirs,owing to its advantages in reducing oil viscosity,improving mobility ratio,quickly replenishing formation pressure,and potentially achieving a miscible state.However,reliable inhouse laboratory evaluation of CO_(2) huff-n-puff in natural conglomerate cores is challenging due to the inherent high formation pressure.In this study,we put forward an equivalent method based on the similarity of the miscibility index and Grashof number to acquire a lab-controllable pressure that features the flow characteristics of CO_(2) injection in a tight conglomerate reservoir.The impacts of depletion degree,pore volume injection of CO_(2) and soaking time on ultimate oil recovery in tight cores from the Mahu conglomerate reservoir were successfully tested at an equivalent pressure.Our results showed that oil recovery decreased with increased depletion degree while exhibiting a non-monotonic tendency(first increased and then decreased)with increased CO_(2) injection volume and soaking time.The lower oil recoveries under excess CO_(2) injection and soaking time were attributed to limited CO_(2) dissolution and asphaltene precipitation.This work guides secure and reliable laboratory design of CO_(2) huff-n-puff in tight reservoirs with high formation pressure.

Characterization on the formation of porosity and tensile properties prediction in die casting Mg alloys

The 3D visualization of the porosity in high-pressure die casting(HPDC)Mg alloys AZ91D and Mg4Ce2Al0.5Mn(EA42)was investigated by X-ray computed tomography.It was demonstrated that the volumetric porosity at the near-gate location for alloy EA42 was significantly higher than that far from the gate location.This difference resulted from the low valid time during intensified casting pressure conditions.Specimens of alloy EA42 exhibited a narrow pore distribution in the side view(~0.5 mm)compared to the wide distribution(~1.8 mm)of alloy AZ91D,which was mainly attributed to the formation mechanism of the defect band.The formation of microporosity in the defect band of alloy EA42 was inhibited because of the significant latent heat released by a large amount of the Al11Ce3phase segregated in the defect band during solidification.Additionally,an effective estimator(Z-Propagation)was introduced,which is proposed to predict the projected area fraction of the porosity(f)involved during tensile failure with better effectiveness compared with traditional methods based on the actual fractured surface.By coupling the Z-Propagation method with the critical local strain model,the logarithmic fracture strain and true fracture stress of the specimens were predicted within 3.03%and 1.65%of the absolute value of the average relative error(AARE),respectively.

数字普惠金融背景下的小额信贷与农户收入

与传统小额信贷相比,以网络平台小额信贷为代表的数字普惠金融不但可以分散风险、降低信息成本,而且可以缓解资金供给不足的困境,因而在小额信贷领域备受期待。本文利用公益性网络借贷平台——宜农贷开展的追踪调查数据,实证考察了宜农贷平台借贷对农户收入的影响。基于倾向得分匹配基础上的双重差分法(PSMDID)分析表明:宜农贷平台借贷促进了农户人均纯收入的提高,且主要是通过提高农户的农业类收入实现。进一步研究发现,宜农贷平台借贷对农户人均纯收入的提高作用与农户人均纯收入水平之间呈现U型关系。因此,本文建议,在处于脱贫攻坚战关键期和加快乡村振兴的当下,政府可以通过政策支持引导以网络平台为媒介的小额信贷来支持贫困地区农村发展,进一步扩大返贫力量和资源。

基于金属有机框架材料的比率荧光印迹探针测定磺胺嘧啶

基于荧光分析法与分子印迹技术,构建了一种可快速、灵敏检测自来水和牛奶中磺胺嘧啶的荧光探针。以磺胺嘧啶为模板分子,3-氨丙基三乙氧基硅烷为功能单体,金属有机框架材料(MOFs)为载体,将碲化镉量子点(CdTe QDs)包埋于MOFs中,镁氮共掺杂的石墨烯量子点(Mg, N/GQDs)为响应信号,通过溶胶凝胶法制备了荧光分子印迹探针。对合成探针的形貌、化学结构和性能进行表征。结果显示,磺胺嘧啶浓度在0~100μmol/L范围内,与荧光强度呈良好的线性关系,检出限为11.23 nmol/L,回收率在96.2%~101.2%之间,相对标准偏差(RSD)小于1.7%。该探针已成功应用于实际样品自来水和牛奶中磺胺嘧啶的检测。

Visualizing the crystallization of sodium chloride under supersaturated condition

Crystallization in supersaturated solution plays a fundamental role in a variety of natural and industrial processes.However,a thorough understanding of crystallization phenomena in supersaturated solution is still difficult because the real-time visualization of crystallization processes under supersaturated condition is a great challenge.Herein,an electron beam-induced crystallization method was carried out in in situ liquid cell transmission electron microscopy(TEM)to visualize the crystallization of NaCl under supersaturated condition in real time.Crucial steps and behaviors in the crystallization of NaCl were captured and clarified,including the growth of NaCl nanocrystals with different morphologies,the formation of initial crystalline seeds from amorphous ion clusters,and the non-equilibrium growth behaviors caused by uneven distribution of precursor ions.This study provides the real-time visualization of detailed nucleation and growth behaviors in NaCl crystallization and brings an ideal strategy for investigating crystallization phenomena under supersaturated condition.

Recent progress in application of nanovaccines for enhancing mucosal immune responses

Mucosal vaccines that stimulate both mucosal and systemic immune responses are desirable,as they could prevent the invading pathogens at their initial infection sites in a convenient and userfriendly way. Nanovaccines are receiving increasing attention for mucosal vaccination due to their merits in overcoming mucosal immune barriers and in enhancing immunogenicity of the encapsulated antigens.Herein, we summarized several nanovaccine strategies that have been reported for enhancing mucosal immune responses, including designing nanovaccines that have superior mucoadhesion and mucus penetration capacity, designing nanovaccines with better targeting efficiency to M cells or antigen-presenting cells, and co-delivering adjuvants by using nanovaccines. The reported applications of mucosal nanovaccines were also briefly discussed, including prevention of infectious diseases, and treatment of tumors and autoimmune diseases. Future research progresses in mucosal nanovaccines may promote the clinical translation and application of mucosal vaccines.

An antigen self-assembled and dendritic cell-targeted nanovaccine for enhanced immunity against cancer

The rise of nanotechnology has opened new horizons for cancer immunotherapy.However,most nano vaccines fabricated with nanomaterials suffer from carrier-related concerns,including low drug loading capacity,unpredictable metabolism,and potential systemic toxicity,which bring obstacles for their clinical translation.Herein,we developed an antigen self-assembled nanovaccine,which was resulted from a simple acryloyl modification of the antigen to induce self-assembly.Furthermore,a dendritic cell targeting head mannose monomer and a mevalonate pathway inhibitor zoledronic acid(Zol)were integrated or absorbed onto the nanoparticles(denoted as MEAO-Z)to intensify the immune response.The synthesized nano vaccine with a diameter of around 70 nm showed successful lymph node transportation,high dendritic cell internalization,promoted costimulatory molecule expression,and preferable antigen cross-presentation.In virtue of the above superiorities,MEAO-Z induced remarkably higher titers of serum antibody,stronger cytotoxic T lymphocyte immune responses and IFN-γsecretion than free antigen and adjuvants.In vivo,MEAO-Z significantly suppressed EG7-OVA tumor groth and prolonged the survival time of tumor-bearing mice.These results indicated the translation promise of our self-assembled nano vaccine for immune potentiation and cancer immunotherapy.

Analysis of the CDR3 Length Repertoire and the Diversity of TCRα Chain in Human Peripheral Blood T Lymphocytes

Analysis of complementarity determining region 3 （CDR3） length of T lymphocyte receptors （TCRs） by immunoscope spectratyping technique has been used successfully to investigate the diversity of TCR in autoimmune diseases and infection diseases. In this study, we investigated the patterns of CDR3 length distribution for all 32 TCR AV gene families in human peripheral blood lymphocytes of four normal volunteers by the immunoscope spectratyping technique. It was found that PCR products exhibited an obscure band on 1.5% agarose gel electrophoresis. Each TCR AV family exhibited more than 8 bands on 6% sequencing gel electrophoresis. The CDR3 spectratyping of all TCR AV families showed a standard Gaussian distribution with different CDR3 length, and the expression frequency of CDR3 was similar among the gene families. Most of CDR3 in TCR AV family recombine in frame. However, some of the CDR3 showed out-of frame gene rearrangement. Additionally, we found that in some of TCR AV families there were 18 amino acid discrepancies between the longest CDR3 and shortest CDR3. These results may be helpful to further study the recombination mechanism of human TCR genes, the TCR CDR3 gene repertoire, and the repertoire drift in health people and disease state. Cellular ＆ Molecular Immunology.

Highly pathogenic coronaviruses: thrusting vaccine development in the spotlight

Coronaviruses(CoVs)are a large family of viruses that cause illness ranging from the common cold to more severe diseases such as Severe Acute Respiratory Syndrome(SARS)and Middle East Respiratory Syndrome(MERS).Severe Acute Respiratory Syndrome coronavirus 2(SARS-CoV-2)disease(COVID-19)has caused major public health crises.There have been more than 4,400,000 reported cases of COVID-2019 and more than 300,000 reported deaths to date(16/05/2020).SARS-CoV,MERSCoV and SARS-CoV-2 have attracted widespread global attention due to their high infectivity and pathogenicity.To date,there is no specific treatment proven effective against these viral infectious diseases.Vaccination is considered one of the most effective strategies to prevent viral infections.Therefore,the development of effective vaccines against highly pathogenic coronaviruses is essential.In this review,we will briefly describe coronavirus vaccine design targets,summarize recent advances in the development of coronavirus vaccines,and highlight current adjuvants for improving the efficacy of coronavirus vaccines.

Cystathionine-γ-lyase ameliorates the histone demethylase JMJD3-mediated autoimmune response in rheumatoid arthritis

Cystathionine-γ-lyase(CSE),an enzyme associated with hydrogen sulfide(H2S)production,is an important endogenous regulator of inflammation.Jumonji domain-containing protein 3(JMJD3)is implicated in the immune response and inflammation.Here,we investigated the potential contribution of JMJD3 to endogenous CSE-mediated inflammation in rheumatoid arthritis(RA).Upregulated CSE and JMJD3 were identified in synovial fibroblasts(SFs)from RA patients as well as in the joints of arthritic mice.Knocking down CSE augmented inflammation in IL-1β-induced SFs by increasing JMJD3 expression.In addition,CSE−/−mice with collagen-induced arthritis(CIA)developed severe joint inflammation and bone erosion.Conversely,overexpressing CSE inhibited JMJD3 expression by the transcription factor Sp-1 and was accompanied by reduced inflammation in IL-1β-treated SFs.Furthermore,JMJD3 silencing or the administration of the JMJD3 inhibitor GSK-J4 significantly decreased the inflammatory response in IL-1β-treated SFs,mainly by controlling the methylation status of H3K27me3 at the promoter of its target genes.GSK-J4 markedly attenuated the severity of arthritis in CIA mice.In conclusion,suppressing JMJD3 expression by the transcription factor Sp-1 is likely responsible for the ability of CSE to negatively modulate the inflammatory response and reduce the progression of RA.