The effect of gravity on self-similarity of Worthington jet after water entry of a two-dimensional wedge

The effect of gravity on the self-similarity of jet shape at late stage of Worthington jet development is investigated by experiment in the study.In addition,the particle image velocimetry(PIV)method is introduced to analyze the development of flow field.There is a linear scaling regarding the axial velocity of the jet and the scaling coefficient increases with the Froude number.

Lithiation-induced controllable vacancy engineering for developing highly active Ni_(3)Se_(2) as a high-rate and large-capacity battery-type cathode in hybrid supercapacitors

The poor rate capability and low capacity are huge barriers to realize the commercial applications of battery-type transition metal compounds(TMCs) cathode.Herein,numerous Se vacancy defects are introduced into the Ni_(3)Se_(2)lamellas by pre-lithiation technique,which can be acted as a novel class of battery-type cathode for hybrid supercapacitors.Appropriately modulating the contents of the preembedded lithium(Li) ions can induce a controllable vacancy content in the series of as-prepared products,effectively endowing a fast reaction kinetic and high activity for the cathode.Benefiting from the distinct design,the optimized cathode(Li2-Ni_(3)Se_(2)) presents a high specific capacity of 236 mA h g^(-1)at1 A g^(-1),importantly,it can still possess 117 mA h g^(-1)when the current density is increased up to 100A g^(-1),exhibiting relatively high rate capability.It is much superior to other battery-type TMC cathodes reported in previous studies.Moreover,the cathode also shows the excellent cycling stability with 92%capacity retention after 3,000 cycles.In addition,a hybrid supercapacitor(HSC) is assembled with the obtained Li2-Ni_(3)Se_(2)as the cathode and active carbon(AC) as the anode,which delivers a high energy density of 77 W h kg^(-1)at 4 kW kg^(-1)and long-term durability(90% capacitance retention after 10,000 cycles).Therefore,the strategy not only provides an effective way to realize the controllable vacancy content in TMCs for achieving high-perfo rmance cathodes for HSC,but also further promotes their large-scale applications in the energy storage fields.

Effectively Modulating Oxygen Vacancies in Flower‑Likeδ‑MnO_(2)Nanostructures for Large Capacity and High‑Rate Zinc‑Ion Storage

In recent years,manganese-based oxides as an advanced class of cathode materials for zinc-ion batteries(ZIBs)have attracted a great deal of attentions from numerous researchers.However,their slow reaction kinetics,limited active sites and poor electrical conductivity inevitably give rise to the severe performance degradation.To solve these problems,herein,we introduce abundant oxygen vacancies into the flower-likeδ-MnO_(2)nanostructure and effectively modulate the vacancy defects to reach the optimal level(δ-MnO_(2)-x-2.0).The smart design intrinsically tunes the electronic structure,guarantees ion chemisorption-desorption equilibrium and increases the electroactive sites,which not only effectively accelerates charge transfer rate during reaction processes,but also endows more redox reactions,as verified by first-principle calculations.These merits can help the fabricatedδ-MnO_(2)-x-2.0 cathode to present a large specific capacity of 551.8 mAh g^(-1) at 0.5 A g^(-1),high-rate capability of 262.2 mAh g^(-1) at 10 A g^(-1) and an excellent cycle lifespan(83%of capacity retention after 1500 cycles),which is far superior to those of the other metal compound cathodes.In addition,the charge/discharge mechanism of theδ-MnO_(2)-x-2.0 cathode has also been elaborated through ex situ techniques.This work opens up a new pathway for constructing the next-generation high-performance ZIBs cathode materials.

Analysis of the effect of holmium laser flexible ureteroscopic intrapelvic drainage in the treatment of parapelvic renal cysts

Objective:To explore the efficacy,safety,and feasibility of holmium laser flexible ureteroscopic intrapelvic drainage in the treatment of parapelvic renal cysts.Methods:From September 2012 to February 2019,a total of 18 patients,aged from 28 to 62(meanstandard deviation[SD]:46.50±9.14)years,were diagnosed with parapelvic renal cysts and treated by holmium laser flexible ureteroscopic intrapelvic drainage.There were 10 males and eight females.All of the parapelvic renal cysts were unilateral,and two cases were complicated with pyelolithiasis.The diameters of the cysts ranged from 4.1 cm to 8.2 cm.Results:All the patients completed the operation successfully in one stage without conversion to open surgery;in two cases,it was difficult to find the cysts during the operation,and the localization was completed by B-ultrasound and percutaneous injection of methylene blue.The mean operative time was 33.89(SD:9.68;range:22-54)min,and the mean hospitalization time was 2.67(SD:0.91;range:2-5)days.Three months and 6 months of follow-up were performed after surgery.The cysts disappeared in 13(72%)cases,and the diameter of the cysts in five(28%)cases decreased by more than 50%.Conclusion:Holmium laser flexible ureteroscopic intrapelvic drainage in the treatment of parapelvic renal cysts is simple,safe,and effective,and can be used as the first choice for the treatment of parapelvic renal cysts.

Analysis of Rainstorm Process in South China from September 7 to 8, 2022

Based on the NCEP data of the United States, a rainstorm process in South China during September 7 to 8, 2022 was studied. Synoptic method is a qualitative and empirical forecasting method. The results show that: In early September 2022, the cold air behind the trough line from northeast China to North China can directly drive southward and invade South China from the east road. Typhoon Hinnamnor is located in the saddle field between the mainland subtropical high and the offshore subtropical high. It moves northward on the west side of the coastal subtropical high, affecting the Taiwan Island and the coastal areas of East China. During September 7-8, the wave trough of the 925 hPa Easterly wave was located near 110°E. Easterly jet existed in the southeast of South China. The center of the easterly jet was located to the east of Hainan Island, which could transport abundant water vapor from the sea surface to the sky over South China. The precipitable water in the whole layer of the atmosphere decreased from the southern coastal areas to the north, reaching more than 50 mm in southern China, of which most of the South China Sea, Hainan Island and parts of the western part of Guangdong Province exceeded 60 mm, providing sufficient water vapor supply. The circulation field with convergence at low level and divergence at high level is conducive to vertical uplift to form precipitation.

Longitudinal Measurement of Hemodynamic Changes within the Posterior Optic Nerve Head in Rodent Nonarteritic Anterior Ischemic Optic Neuropathy

ObjectiveTo assess the in vivo dynamic blood flow features of posterior optic nerve head (ONH) in rat model of nonarteritic anterior ischemic optic neuropathy (rNAION). MethodsrNAION was established with Rose Bengal and argon green laser in Sprague-Dawley rats. Fundus photography and fundus fluorescein angiography (FFA) were performed to assess the dynamic changes of optic disc in morphology in 90 days and in blood perfusion in 3 hours after the induction of disease. Histological examinations were performed to evaluate the success of modeling. Thedynamic blood flow kinetics of posterior ONH in rNAION were measured by Laser Doppler Flowmetry (LDF) on the day 3, 7, 14, 21, and 40 after the disease induction. One-way ANOVA, Student'st-test and Bonferroni adjustment were used for multiple comparisons of kinetic measurements of blood flow. ResultsOptic disc edema and subsequent resolution associated with the development of optic disc pallor were observed in rNAION. FFA showed that the optic disc was hypofluorescence in the early phase and hyperfluorescence in the late phase. Histological studies suggested edema and loosened tissues of ONH, loss of retinal ganglion cells (RGCs), optic nerve substance and gliosis. Compared to the naive rats, the blood flow kinetics of posterior ONH in rNAION significant reduced at each time point after modeling (F=175.06,P<0.0001). The reductions were specifically remarkable in 14 days after the disease induction (AllP<0.01). Conclusions Continuous blood perfusion reduction was found in rNAION, with significant alteration in 14 days after disease induction. Our results provided important information for understanding the hemodynamic changes in rNAION.

Constant False Alarm Rate Acquisition Algorithm for Compass B1C Signal

In order to improve the sensitivity of the Compass B1C signal acquisition for the receiver,the principle of constant false alarm rate(CFAR)is applied for the B1C pilot channel acquisition to realize the dynamic adjustment of the threshold of acquisition against the carrier to noise ratio.The non-coherent data/pilot combined acquisition algorithm for B1C signal is analyzed to make full use of the power of the B1C signal under the condition of low carrier to noise ratio.On this basis,to improve the acquisition sensitivity of the receiver,the principle of constant false alarm probability is applied for the non-coherent data/pilot combined acquisition algorithm.Theoretical analysis and simulations show that the non-coherent data/pilot combined acquisition algorithm with CFAR improves the B1C signal acquisition sensitivity of the receiver significantly,and achieves a better Receiver Operating Characteristic compared with the traditional acquisition algorithms.

Passive control of cavitating flow around an axisymmetric projectile by using a trip bar

Quasi-periodical evolutions such as shedding and collapsing of unsteady cloud cavitating flow, induce strong pressure fluctuations, what may deteriorate maneuvering stability and corrode surfaces of underwater vehicles. This paper analyzed effects on cavitation stability of a trip bar arranged on high-speed underwater projectile. Small scale water tank experiment and large eddy simulation using the open source software Open FOAM were used, and the results agree well with each other. Results also indicate that trip bar can obstruct downstream re-entrant jet and pressure wave propagation caused by collapse, resulting in a relatively stable sheet cavity between trip bar and shoulder of projectiles.

A numerical model for cloud cavitation based on bubble cluster

The cavitation cloud of different internal structures results in different collapse pressures owing to the interaction among bubbles. The internal structure of cloud cavitation is required to accurately predict collapse pressure. A cavitation model was developed through dimensional analysis and direct numerical simulation of collapse of bubble cluster. Bubble number density was included in proposed model to characterize the internal structure of bubble cloud. Implemented on flows over a projectile, the proposed model predicts a higher collapse pressure compared with Singhal model. Results indicate that the collapse pressure of detached cavitation cloud is affected by bubble number density.

Experiment and numerical simulation on the characteristics of fluid–structure interactions of non-rigid airships

Fluid-structure interaction is an important issue for non-rigid airships with inflated envelopes. In this study, a wind tunnel test is conducted, and a loosely coupled procedure is correspondingly established for numerical simulation based on computational fluid dynamics and nonlinear finite element analysis methods. The typical results of the numerical simulation and wind tunnel experiment, including the overall lift and deformation, are in good agreement with each other. The results obtained indicate that the effect of fluid-structure interaction is noticeable and should be considered for non-rigid airships. Flow- induced deformation can further intensify the upward lift force and pitching moment, which can lead to a large deformation. Under a wind speed of 15 m/s, the lift force of the non-rigid model is increased to approximatelv 60% compared with that of the rigid model under a high angle of attack.

A novel spherical-headed fascial dilator is feasible for second-stage ultrasound guided percutaneous nephrolithotomy:A pilot study

Objective:In second-stage percutaneous nephrolithotomy(PCNL),because the hydronephrosis has been decompressed,the dilated renal pelvis has resolved and the space is small.Consequently,introduction of the tip of the Amplatz dilator can cause injury to the opposite side of the renal-pelvic mucosa.In this study,we report the experimental and initial clinical performance of a spherical-headed fascial dilator developed specifically for second-stage PCNL.Methods:The novel spherical-headed dilator was compared with existing tapered-headed dilators in configuration and in puncture resistance utilizing a static puncture test.Subsequently,a pilot clinical study was conducted during which patients scheduled to undergo second-stage PCNL from June 2019 to October 2019 in our center were enrolled.A typical ultrasound guided PCNL procedure was performed with the exception that the new spherical-headed fascial dilator was substituted for a tapered-headed one.Results:Experimentally,stab resistance against polyethylene film was significantly increased using the novel spherical-headed dilator compared to the traditional tapered-headed dilators(p<0.005).In the clinical study,the novel dilators were successfully introduced into the renal pelvis and passed down the collecting system in all eight second-stage PCNL cases.There were no cases of renal pelvic perforation or brisk hemorrhage nor need for transfusion.

Dynamic mode decomposition and reconstruction of transient cavitating flows around a Clark-Y hydrofoil

The transient cavitating flow around the Clark-Y hydrofoil is numerically investigated by the dynamic mode decomposition with criterion.Based on the ranking dominant modes,frequencies of the first four modes are in good accordance with those obtained by fast Fourier transform.Furthermore,the cavitating flow field is reconstructed by the first four modes,and the dominant flow features are well captured with the reconstructed error below 12%when compared to the simulated flow field.This paper offers a reference for observing and reconstructing the flow fields,and gives a novel insight into the transient cavitating flow features.

Development of EPDM composites reinforced by CNTs@SiO_(2)for thermal protection systems of aerospace propulsion:Significant improvement in oxidation and ablation resistance properties

Carbon Nanotubes(CNTs)reinforced Polymer-Matrix Composites(PMCs)is widely used as insulation materials in thermal protection system of aerospace propulsion.However,CNTs are prone to oxidation and have high thermal conductivities,which makes it difficult to improve the ablation resistance of insulation materials that contain CNTs.SiO_(2)was encapsulated onto the surface of CNTs(CNTs@SiO_(2)),which were then added to Ethylene Propylene Diene Monomer(EPDM)rubber to prepare the insulation materials.Thermogravimetric analysis and ablation test were used to evaluate the resistance of the insulation materials to thermal oxidation and ablation.Additionally,scanning electron microscopy was performed to analyze their microstructures.Results revealed that the addition of CNTs@SiO_(2)could visibly reduce the effects of hot corrosion and ablation on insulation materials.The C-CNTs@SiO_(2)-1 formulation had the best ablative resistance.Further,compared with the unencapsulated formulation(C-CNTs-10),the C-CNTs@SiO_(2)-1 formulation reduced the line ablation rate by 51%to 0.0130 mm/s after oxygen-acetylene experiments.Lastly,the ablation mechanism was investigated based on the effects of the CNTs@SiO_(2)additive on their properties.Thus,the improvement in ablation performance may be attributed to CNTs@SiO_(2)-induced decreases in thermal conductivity,improvement in the hot corrosion resistance in the char layer,and changes in the microstructure.

全球跨境水资源冲突与解决方案的研究综述

水资源冲突是关系到区域安全和全球可持续发展的关键科学问题。随着全球气候变化的加剧,水资源时空分布变化导致水冲突问题呈现更复杂和更不确定态势。本文基于全球近百年来1 240件水冲突事件的时空分布特征,立足资源科学、经济学、国际政治学等理论,揭示出各地区水冲突的产生有其自然生态、社会经济、历史文化、国际政治的根源,进而从资源稀缺、流域国际化与国家间水权力不对称、水合作机制缺失与失灵三个角度剖析水冲突的原因。最后,从传统的技术、经济手段向国际关系、国际谈判的视角探求目前的解决机制,提出立足各地区自然、经济、历史特征和发展诉求,通过增进区域利益共享、开展综合流域规划、加强国际条约的执行力等措施探寻适合跨境水资源冲突的协调机制和解决方案。

LPS adsorption and inflammation alleviation by polymyxin B-modified liposomes for atherosclerosis treatment

Chronic inflammation is critical in the onset and progression of atherosclerosis(AS).The lipopolysaccharide(LPS)level in the circulation system is elevated in AS patients and animal models,which is correlated with the severity of AS.Inspired by the underlying mechanism that LPS could drive the polarization of macrophages toward the M1 phenotype,aggravate inflammation,and ultimately contribute to the exacerbation of AS,LPS in the circulation system was supposed to be the therapeutic target for AS treatment.In the present study,polymyxin(PMB)covalently conjugated to PEGylated liposomes(PLPs)were formulated to adsorb LPS through specific interactions between PMB and LPS.In vitro,the experiments demonstrated that PLPs could adsorb LPS,reduce the polarization of macrophages to M1 phenotype and inhibit the formation of foam cells.In vivo,the study revealed that PLPs treatment reduced the serum levels of LPS and pro-inflammatory cytokines,decreased the proportion of M1-type macrophages in AS plaque,stabilized AS plaque,and downsized the plaque burdens in arteries,which eventually attenuated the progression of AS.Our study highlighted LPS in the circulation system as the therapeutic target for AS and provided an alternative strategy for AS treatment.

具有O–Fe–Se配位键的半共格异质界面工程提高电池型超级电容器阳极的容量和倍率

低容量和低倍率限制了电池型超级电容阳极材料的大规模应用.本文通过构建一种具有半共格异质界面特性的Fe_(2)O_(3)/FeSe_(2)纳米结构作为先进的阳极材料来解决这一瓶颈.系列表征和第一性原理计算表明,这种特殊的异质界面不仅能自发产生较强的内建电场,从而提高电子传递速率和OH^(-)离子的吸附能力;还可使得活性物质与OH^(-)之间发生更多的氧化还原反应,并且使该反应体系更容易进行.基于上述优势,所制备出的阳极材料的最大比容量为199.2 mA h g^(-1)(1 A g^(-1)),并且在10 A g^(-1)下仍能保持105.8 mA h g^(-1),同时,经历5000次循环后,其比容量可维持初始值的90.2%.此外,以Fe_(2)O_(3)/FeSe_(2)作为阳极组装的非对称超级电容器在0.8 kW kg^(-1)时的能量密度为52.55 Wh kg^(-1),即使经历15,000次循环,该器件还能维持初始容量的91.2%.我们的工作为设计大容量和高倍率性能的电池型超级电容器阳极材料提供了一种创新性的策略,有望推动过渡金属化合物在储能系统中的大规模应用.

The Mechanisms of Luteolin in Treating COVID-19 Based on Bioinformatics Analysis and Molecular Docking

Luteolin is a natural flavonoid that has a variety of pharmacological activities, such as anti-inflammatory, anti-allergic, anti-bacterial, anti-viral, apoptosis inhibition, cell autophagy regulation, and anti-tumor activity. It is one of the main ingredients of an expert-recommended herbal formula for the prevention and treatment of coronavirus disease 2019 (COVID-19). This suggests that luteolin has strong pharmacological effects on the prevention and treatment of COVID-19. The aims of this study were to identify the molecular targets of luteolin and to infer the possible mechanisms by which it exerts its pharmacological effects. The GSE159787 data set was obtained from the Gene Expression Omnibus online database, and differentially expressed genes were analyzed. There were 22 upregulated differentially expressed genes enriched in the COVID-19 signaling pathway, suggesting that the upregulation of these genes may be closely related to the occurrence of COVID-19. Molecular docking results showed that luteolin had strong binding efficiency to 20 of these 22 key genes. Six of these genes (CFB, EIF2AK2, OAS1, MAPK11, OAS3, and STAT1) showed strong binding activity. Luteolin can regulate the COVID-19 signaling pathway by combining with these targets, which may have a therapeutic effect on COVID-19.

Rapid detection of cordycepin in food by surface-enhanced Raman technique

In this paper,a method for rapid detection of cordycepin in food was established based on surface-enhanced Raman spectroscopic analysis method.The surface-enhanced Raman substrates were screened and the Raman detection conditions and sample pretreatment methods were optimized.The optimal substrate was gold nanocolloid,and the optimal detection conditions were as follows:the addition amount of gold nanocolloid was 200μL of gold nanocolloid and the sample addition amount was 5μL.Under the optimal conditions,the detection limit of cordycepin was 1 mg/L,and the sample pretreatment was performed by methanol extraction.Based on the established surface-enhanced Raman spectroscopy(SERS)method,cordycepin in two Cordyceps militaris was detected,which confirmed the practical application of this method.

Flavonoid profiling of a traditional Chinese medicine formula of Huangqin Tang using high performance liquid chromatography

The quality control processes for herbal medicines have been problematic. Flavonoids are the major active components of Huangqin Tang(HQT, a traditional Chinese medicine formula). In this study, we used a combinative method approach consisting of chromatographic fingerprinting(high performance liquid chromatography; HPLC), quantitative methods and a pharmacodynamic evaluation model to analyze the flavonoids of HQT obtained from different sources. Ten batches of HQT were analyzed by the HPLC fingerprinting method and 26 common peaks were detected, of which 23 peaks corresponded with the chemical profile of HQT. In addition, 11 major compounds were identified by LC–MS analysis(liquid chromatography–tandem mass spectrometer; LC–MS^n) and quantified by the HPLC quantitative method approach. The studied10 batches of HQT were found to be homogeneous in their composition with a similarity between 0.990 and1.000. The distribution of the 11 identified compounds was found to be very similar among the batches. Only slight pharmacodynamic differences were detected between the different batches, confirming the homogeneity of HQT. The results of this study prove that the combination of chromatographic fingerprinting and quantitative analysis can be readily used for comprehensive quality control of herbal medicines.

Deformation behavior of non-rigid airships in wind tunnel tests

Deformation behavior of non-rigid airships in wind tunnel tests is studied by considering three factors, including internal pressure, flow velocity and angle of attack. Fiber Bragg grating strain sensors are used to measure the deformation of non-rigid airships. Wind tunnel tests in the case of different flow velocities and angles of attack are conducted. The measurement results reveal that the airship deformation is in proportion to internal pressure. For the tensile region,the airship deformation is in proportion to flow velocity. Effects of angle of attack on structural deformation are more complicated and there is no clear relationship existing between airship deformation and angle of attack.