Slope Stability Considering the Top Building Load

Slope stability is one of the most important subjects of geotechnics. The slope top-loading plays a key role in the stability of slopes in hill slope areas. When the building load is too large or the point of action from the shoulder is too close, the shear stress of the slope will be significantly greater than its shear strength, resulting in reduced slope stability. Therefore, it is of great importance to study the relationship between the building load and the stability of the slope. This study aims to analyze the influence of different building loads applied at different distances on the top of the slope and deduces their effects on the slope stability. For this purpose, a three-dimensional slope model under different building loads with different distances to the slope shoulder was established using the finite-difference analysis software Flac3D. The results show that the loads applied at different distances on the top of the slope have different effects on the slope stability. The slope factor of safety (FOS) increases with the increase of the distance between the top-loading and the slope shoulder;it varies from 1.37 to 1.53 for the load P = 120 KPa, 1.27 to 1.53 for the load P = 200 KPa, and from 1.18 to 1.44 for P = 300 KPa, resulting in the decrease of the coincidence area between the load-deformation and the potential sliding surface. The slope is no longer affected by the potential risk of sliding at approximately 20 m away from the slope shoulder.

交流计划提高了香港青年大学生对大湾区内地城市的了解和好感吗?--基于随机对照实验的实证分析

提高香港青年大学生对内地的了解,促进他(她)们“北上”到内地发展并融入国家发展大局,是我国“港澳与内地高校师生交流计划”(以下简称交流计划)的政策目标之一。该交流计划自2012年开始已经实施多年,但其政策效果究竟如何还未有研究。本研究结合研学旅行相关理论和群际接触理论,使用随机对照实验设计考察交流计划短期项目的政策效果,即交流计划是否增进了香港青年大学生对大湾区内地城市及其发展的兴趣和了解,以及对这些城市的好感。研究发现,大部分愿意参加交流计划的香港青年大学生对大湾区内地城市及其发展感兴趣,而且对大湾区内地城市有好感,但并不了解大湾区内地城市及其发展;交流计划显著提高了香港青年大学生对大湾区内地城市及其发展的兴趣和了解;参加了交流计划的香港青年大学生对大湾区内地城市变得更有好感的比例要高于没有参加交流计划的学生,但差异并不显著。本研究为评估交流计划在增强香港青年大学生对内地了解的有效性提供了首个定量实证证据,为国家制定和完善有关香港青年大学生的政策提供了有益的启示。

Experimental and computational studies on the flow fields in aortic aneurysms associated with deployment of AAA stent-grafts

Pulsatile flow fields in rigid abdominal aortic aneurysm （AAA） models were investigated numerically, and the simulation results are found in good agreement with particle image velocimetry （PIV） measurements. There are one or more vortexes in the AAA bulge, and a fairly high wall shear stress exists at the distal end, and thus the AAA is in danger of rupture. Medical treatment consists of inserting a vascular stent-graft in the AAA, which would decrease the blood impact to the inner walls and reduce wall shear stress so that the rupture could be prevented. A new computational model, based on porous medium model, was developed and results are documented. Therapeutic effect of the stent-graft was verified numerically with the new model.

Active loading liposomal irinotecan hydrochloride:Preparation,in vitro and in vivo evaluation

The aim of the present study was to investigate the effect of various transmembrane ammonium salt gradients and different lipid composition on the loading efficiency of liposomal formulations of irinotecan hydrochloride(CPT-11),their behavior in vivo and cytotoxicity.Among ammonium salts studied,ammonium sulfate was successfully used to load CPT-11 into liposomes with the highest encapsulation efficiency.Subsequently,liposomal CPT-11 with different lipid composition was prepared by ammonium sulfate gradient method.CPT-11 can be loaded to a level over 90%into liposomes composed of soybean phospholipids/cholesterol(SPC-L)or hydrogenated natural soybean phospholipids/cholesterol(HSPC-L).In vitro release profiles were also investigated,indicating that HSPC-L had a lower release than that in SPC-L.In vivo,encapsulation of CPT-11 in both liposomal formulations showed higher area under the curve(AUC),a lower rate of clearance(CL)and smaller volume of distribution for CPT-11 than those of irinotecan hydrochloride solution(CPT-11-S).However,CL and AUC of 7-ethyl-10-hydroxycamptothecin(SN-38)were moderately improved in HSPC-L group.Based on the results of comparative pharmacokinetics of liposomal CPT-11 with different lipid composition,the in vitro cytotoxicity of HSPC-L was evaluated with human tumor cell.The result indicated that liposomal CPT-11 showed a great enhancement in vitro cytotoxicity.The results suggested that entrapment of CPT-11 in liposomes especially in those with high phase-transition temperature lipid by ammonium sulfate gradient would be a promising formulation with a better in vivo behavior.

Resveratrol inhibits angiotensin II-induced ERK1/2 activation by downregulating quinone reductase 2 in rat vascular smooth muscle cells

Our previous studies showed that resveratrol could inhibit the proliferation of vascular smooth muscle cells （VSMCs） and repress mRNA and protein expression of quinone reductase 2 （NQO2）. This study further explored the potential mechanisms whereby resveratrol inhibits the proliferation of rat VSMCs. Lentiviral vectors that incorporated NQO2 small interfering RNA （siRNA） were constructed and transduced into rat VSMCs. The cell proliferation was detected using the bromodeoxyuridine （BrdU） assay. Cultured rat VSMCs were stimulated with angiotensin II and the level of reactive oxygen species （ROS） was measured using a ROS assay kit. A realtime quantitative PCR was used to detect NQO2 mRNA levels. Extracellular signal-regulated kinase （ERK1/2） and NQO2 protein expression were determined by Western blotting analysis. The inhibitory effect of resveratrol （10 and 50 μmol/L） on the proliferation of rat VSMCs in the NQO2 siRNA group was significantly weaker than that in the normal and scrambled siRNA group （P 〈 0.01）. The ROS level in the NQO2 siRNA and resveratrol （50 μmol/L） treatment groups were lower than that in the normal and scrambled siRNA groups （P 〈 0.01 in both）. Compared with the normal and scrambled siRNA group, the phosphorylation of ERK1/2 was significantly decreased in the NQO2 siRNA and resveratrol （50 μmol/L） treatment group （P 〈 0.01 in both）. In conclusion, high concentration of resveratrol inhibits angiotensin II-induced ERK1/2 phosphorylation and subsequent proliferation by down-regulation of NQO2 in cultured rat VSMCs.

老年群体数字化生存能力研究

随着信息技术在社会生活应用逐渐泛化,对人们的数字化能力要求逐渐提高。老年群体由于专业知识缺乏和数字化能力不足,融入数字化社会生活困难重重,不仅影响他们生活质量,还可能引发一系列的社会问题。研究受教育水平、收入水平、家庭数字反哺水平以及社交水平四个因素对数字化生存能力的影响,开展影响机制分析,并运用多元线性回归分析进行实证研究。研究结果表明,老年群体数字化生存能力较低,较高的受教育水平、收入水平、家庭数字反哺水平以及社交水平会显著促进老年群体数字生存能力的提高。应采取加大适老化产品研发奖励力度、提升老年群体数字素养和能力、保障老年群体信息安全、家庭数字反哺和强化社交工具适老化改造等举措,推动老年群体顺利融入数字社会。

元宇宙视域下智慧康养应用研究

随着虚拟现实、增强现实、人工智能、区块链等相关技术的进步,以及全球面临的人口老龄化问题愈发严重,智慧康养领域也开始积极拥抱元宇宙。文章梳理了元宇宙视域下智慧康养价值,挖掘元宇宙关于解决养老问题的理念基因,理清元宇宙视域下未来智慧康养发展方向。

Implantable intracortical microelectrodes: reviewing the present with a focus on the future

Implantable intracortical microelectrodes can record a neuron’s rapidly changing action potentials(spikes).In vivo neural activity recording methods often have either high temporal or spatial resolution,but not both.There is an increasing need to record more neurons over a longer duration in vivo.However,there remain many challenges to overcome before achieving long-term,stable,high-quality recordings and realizing comprehensive,accurate brain activity analysis.Based on the vision of an idealized implantable microelectrode device,the performance requirements for microelectrodes are divided into four aspects,including recording quality,recording stability,recording throughput,and multifunctionality,which are presented in order of importance.The challenges and current possible solutions for implantable microelectrodes are given from the perspective of each aspect.The current developments in microelectrode technology are analyzed and summarized.

Recognition model for coated red clover seeds using YOLOv5s optimized with an attention module

The non-destructive recognition of coated seeds is crucial for advancing studies in coating theory.Currently,the recognition of coated seeds heavily relies on manual visual inspection and machine vision detection.However,these methods pose challenges such as high misclassification rates,low recognition efficiency,and elevated labor intensity.In response to the aforementioned challenges,this study leveraged deep learning techniques to develop a coated seed recognition model named YOLO-Coated Seeds Recognition(YOLO-CSR),aiming to address the challenges posed by coated seed recognition tasks.The experiment of this study mainly includes the following steps:First,a seed coating machine was set up to coat red clover seeds,resulting in three types of coated red clover seeds.Subsequently,by collecting images of the three types of coated seeds,a coated seed image dataset was further constructed.Then,the YOLOv5s was built,incorporating the Convolutional Block Attention Module(CBAM)into the model’s backbone to enhance its ability to learn features of coated seeds.Finally,the training results of YOLO-CSR were compared with those of other classical recognition models.The experimental results showed that YOLO-CSR achieved the best recognition performance on the self-built coated seed image dataset.The average precision(AP)for recognizing the three types of coated seeds reached 98.43%,97.91%,and 97.26%,with a mean average precision@0.5(mAP@0.5)of 97.87%.Compared to YOLOv5,YOLO-CSR showed a 1.18%improvement in mAP@0.5.Additionally,YOLO-CSR has a model size of only 14.9 MB,with an average recognition time(ART)of 10.1 ms and a frame per second(FPS)of 99.Experimental results prove that YOLO-CSR can accurately,efficiently,and rapidly recognize coated red clover seeds.The findings of this study provide technical support for the non-destructive recognition of spherical coated seeds.

多巴胺在形觉剥夺性近视中作用的研究进展

近视作为一种全球发病率最高的屈光不正,其趋势日益增加,已成为眼科研究领域的热点。形觉剥夺性近视是实验性近视中较为成熟的造模方法。众多研究报道多巴胺作为一种调控视网膜及眼球生长微环境的神经递质,通过与多巴胺受体、途径间的相互作用,在形觉剥夺性近视的形成和抑制过程中具有重要意义。现就多巴胺对形觉剥夺性近视的影响及其生化机制进行探讨,以期为近视的实验研究提供参考。

The interaction of CaM7 and CNGC14 regulates root hair growth in Arabidopsis

Oscillations in cytosolic free calcium determine the polarity of tip-growing root hairs.The Ca2+channel cyclic nucleotide gated channel 14(CNGC14)contributes to the dynamic changes in Ca^2+concentration gradient at the root hair tip.However,the mechanisms that regulate CNGC14 are unknown.In this study,we detected a direct interaction between calmodulin 7(CaM7)and CNGC14 through yeast two-hybrid and bimolecular fluorescence complementation assays.We demonstrated that the third EF-hand domain of CaM7 specifically interacts with the cytosolic C-terminal domain of CNGC14.A two-electrode voltage clamp assay showed that CaM7 completely inhibitsCNGC14-mediated Ca2+influx,suggesting that CaM7 neg-atively regulates CNGC14-mediated calcium signaling.Fur-thermore,CaM7 overexpressing lines phenocopy the short root hair phenotype of a cngc14 mutant and this phenotype is insensitive to changes in external Ca^2+concentrations.We,thus,identified CaM7-CNGC14 as a novel interacting module that regulates polar growth in root hairs by con-trolling the tip-focused Ca2+signal.

Magnetic two-dimensional layered crystals meet with ferromagnetic semiconductors

The existence of intrinsic ferromagnetic semiconductors(FMSs)in twodimensional(2D)materials has been a long-term concern and pursuit.Recent breakthroughs in the 2D FMSs,such as CrGeTe3 and CrX3(X=Cl,Br,I)from bulk down to monolayer,have stimulated intensive researches on new physical phenomena and creative concepts.This minireview mainly summarizes recent progress of 2D intrinsic FMSs in theoretical side,and focuses on the ongoing strategies proposed to enhance ferromagnetism,involving the mechanisms of magnetic exchange interaction and the significance of magnetic anisotropy.Meanwhile,spin-related multifunctionality with ultrathin FMSs and their van de Waals heterostructures in magnetoelectric,valleytronic,and nondissipative electronic technology are introduced,as well as the current challenges and the prospects in this field are discussed.

Hepatocyte growth factor protects pulmonary endothelial barrier against oxidative stress and mitochondria-dependent apoptosis

Background:Pulmonary microvascular endothelial cells(PMVECs)were not complex,and the endothelial barrier was destroyed in the pathogenesis progress of acute lung injury(ALI)/acute respiratory distress syndrome(ARDS).Previous studies have demonstrated that hepatocyte growth factor(HGF),which was secreted by bone marrow mesenchymal stem cells,could decrease endothelial apoptosis.We investigated whether mTOR/STAT3 signaling acted in HGF protective effects against oxidative stress and mitochondria-dependent apoptosis in lipopolysaccharide(LPS)-induced endothelial barrier dysfunction and ALI mice.Methods:In our current study,we introduced LPS-induced PMEVCs with HGF treatment.To investigate the effects of mammalian target of rapamycin(mTOR)/signal transducer and activator of transcription 3(STAT3)pathway in endothelial oxidative stress and mitochondria-dependent apoptosis,mTOR inhibitor rapamycin and STAT3 inhibitor S3I-201 were,respectively,used to inhibit mTOR/STAT3 signaling.Moreover,lentivirus vector-mediatedmTORC1(Raptor)andmTORC2(Rictor)gene knockdown modifications were introduced to evaluatemTORC1 andmTORC1 pathways.Calcium measurement,reactive oxygen species(ROS)production,mitochondrial membrane potential and protein,cell proliferation,apoptosis,and endothelial junction protein were detected to evaluate HGF effects.Moreover,we used the ALI mouse model to observe the mitochondria pathological changes with an electron microscopein vivo.Results:Our study demonstrated that HGF protected the endothelium via the suppression of ROS production and intracellular calcium uptake,which lead to increased mitochondrial membrane potential(JC-1 and mitochondria tracker green detection)and specific proteins(complex I),raised anti-apoptosis Messenger Ribonucleic Acid level(B-cell lymphoma 2 and Bcl-xL),and increased endothelial junction proteins(VE-cadherin and occludin).Reversely,mTOR inhibitor rapamycin and STAT3 inhibitor S3I-201 could raise oxidative stress and mitochondria-dependent apoptosis even with HGF treatment in LPS-induced endothelial cells.Similarly,mTORC1 as well as mTORC2 have the same protective effects in mitochondria damage and apoptosis.Inin vivo experiments of ALI mouse,HGF also increased mitochondria structural integrity via the mTOR/STAT3 pathway.Conclusion:In all,these reveal that mTOR/STAT3 signaling mediates the HGF suppression effects to oxidative level,mitochondria-dependent apoptosis,and endothelial junction protein in ARDS,contributing to the pulmonary endothelial survival and barrier integrity.

Nucleation and growth mechanism of cefodizime sodium at different solvent compositions

The induction time of cefodizime sodium was measured in ethanol-water at different solvent composi- tions by the laser technology measurement. The results indicate that the solvent composition played an important role in the supersaturation and the nucleation process of cefodizime sodium solution. According to the modified classical nucleation theory, the nucleation and growth mechanism were identified. The correlation results show that heterogeneous nucleation dominated the nucleation process at lower supersaturation, where homogeneous nucleation is the most important mechanism at higher supersaturation. Based on the correlated results, the 2D mediated growth mechanism had the highest correlation coefficients （R2）, so this mechanism was selected as the proper growth mechanism for cefodizime sodium.

Characteristics of secondary droplets produced by the impact of drops onto a smooth surface

This work investigates the splashing behaviors of droplets impacting on solid surfaces and mainly focuses on the characteristics of secondary droplets.According to the experimental results,two different splashing patterns,corona splash and levitating-lamella breakup,are observed.A new breakup mode,named rimsegmenting,is found during the levitating-lamella breakup.In particular,the detailed information of the splashing secondary droplets,including the size,velocity,angle,and total volume of the splashing secondary droplets is obtained from the experimental data.The size distribution of the splashing secondary droplets obeys the gamma distribution function.The average diameter and splashing angle of the secondary droplets are mainly related to the Reynolds number Re,and can be expressed as functions of Re.High impact velocity and liquid viscosity will result in a wider size distribution range of splashing secondary droplets.We also put forward an empirical model to predict the total splashing volume,which is consistent with the experimental data both in this work and previous studies.This work is believed to provide insights on the prediction of the characteristics of splashing secondary droplets.

Numerical simulation of polygonal particles moving in incompressible viscous fluids

A two-dimensional coupled lattice Boltzmann immersed boundary discrete element method is introduced for the simulation of polygonal particles moving in incompressible viscous fluids. A collision model of polygonal particles is used in the discrete element method. Instead of a collision model of circular particles, the collision model used in our method can deal with particles of more complex shape and efficiently simulate the effects of shape on particle–particle and particle–wall interactions. For two particles falling under gravity, because of the edges and corners, different collision patterns for circular and polygonal particles are found in our simulations. The complex vortexes generated near the corners of polygonal particles affect the flow field and lead to a difference in particle motions between circular and polygonal particles. For multiple particles falling under gravity, the polygonal particles easily become stuck owing to their corners and edges, while circular particles slip along contact areas. The present method provides an efficient approach for understanding the effects of particle shape on the dynamics of non-circular particles in fluids.

Mechanical behavior of pathological and normal red blood cells in microvascular flow based on modified level-set method

The research of the motion and deformation of the RBCs is important to reveal the mechanism of blood diseases. A numerical method has been developed with level set formulation for elastic membrane immersed in incompressible fluid. The numerical model satisfies mass and energy conservation without the leaking problems in classical Immersed Boundary Method(IBM), at the same time, computing grid we used can be much smaller than the general literatures. The motion and deformation of a red blood cell(including pathological & normal status) in microvascular flow are simulated. It is found that the Reynolds number and membrane's stiffness play an important role in the transmutation and oscillation of the elastic membrane. The normal biconcave shape of the RBC is propitious to create high deformation than other pathological shapes. With reduced viscosity of the interior fluid both the velocity of the blood and the deformability of the cell reduced. With increased viscosity of the plasma both the velocity of the blood and the deformability of the cell reduced. The tank treading of the RBC membrane is observed at low enough viscosity contrast in shear flow. The tank tread fixed inclination angle of the cell depends on the shear ratio and viscosity contrast, which can be compared with the experimental observation well.

Advancements in endometrial epithelial stem cell research

The human endometrium is a dynamic tissue that undergoes approximately 400 cycles of proliferation,decidualization,shedding,and regeneration.With the observation that superficial stratum functionalis loss and swift reepithelization occur every month,an original hypothesis is that stem cells,especially endometrial epithelial stem cells harbored in the deeper basalis,take on the responsibility of repairing and regenerating the endometrial functionalis.

Improved L -phenylglycine synthesis by introducing an engineered cofactor self-sufficient system

L-phenylglycine(L-phg)is a valuable non-proteinogenic amino acid used as a precursor to β-lactam antibiotics,antitumor agent taxol and many other pharmaceuticals.L-phg synthesis through microbial bioconversion allows for high enantioselectivity and sustainable production,which will be of great commercial and environmental value compared with organic synthesis methods.In this work,an L-phg synthesis pathway was built in Escher-ichia coli resulting in 0.23 mM L-phg production from 10 mM L-phenylalanine.Then,new hydroxymandelate synthases and hydroxymandelate oxidases were applied in the L-phg synthesis leading to a 5-fold increase in L-phg production.To address 2-oxoglutarate,NH_(4)^(+),and NADH shortage,a cofactor self-sufficient system was introduced,which converted by-product L-glutamate and NAD^(+)to these three cofactors simultaneously.In this way,L-phg increased 2.5-fold to 2.82 mM.Additionally,in order to reduce the loss of these three cofactors,a protein scaffold between synthesis pathway and cofactor regeneration modular was built,which further improved the L-phg production to 3.72 mM with a yield of 0.34 g/g L-phe.This work illustrated a strategy applying for whole-cell biocatalyst converting amino acid to its value-added chiral amine in a cofactor self-sufficient manner.

A many-body dissipative particle dynamics with energy conservation study of droplets icing on microstructure surfaces

Droplets icing has important applications in real life.The icing process of droplets on microstructure is explored based on the MDPDE method in this study.Firstly,the correctness of the heat transfer model was verified by one-dimensional heat conduction simulation,and then the feasibility of the phase change model was verified by investigating the icing process of droplets.The influence of cold surface temperature,droplet volume and contact angle on freezing time of droplets was discussed,and it was found that the temperature of cold surfaces had a greater effect on freezing.We finally explored the influence of different microstructure surfaces on the icing of droplets,and results showed that the presence of microstructures greatly enhanced the anti-icing effect of the surface.In our research,the contact angle is a relatively large factor affecting the icing of droplets.In addition,it was discovered that the droplet had the strongest ability to delay freezing on the surface of triangle microstructures with a contact angle of 157.1°.