Validation of an axial flow blood pump: computational fluid dynamics results using particle image velocimetry

A magnetically suspended axial flow blood pump is studied experimentally in this article. The pump casing enclosed a three-blade straightener, a two-blade impeller shrouded by a permanent magnet-embedded cylinder, and a three-blade diffuser. The internal flow fields were simulated earlier using computational fluid dynamics (CFD), and the pump characteristic curves were determined. The simulation results showed that the internal flow field was basically streamlined, except the diffuser region. Particle image velocimetry (PIV) measurement of the 1:1 pump model was conducted to validate the CFD result. In order to ensure the optical access, an acrylic prototype was fabricated with the impeller driven by a servomotor instead, as the magnet is opaque. In addition to the transparent model, the blood analog fluid with the refractive index close to that of acrylic was used to avoid refraction. According to the CFD results, the axial flow blood pump could generate adequate pressure head at the rotating speed of 9500rpm and flow rate of 5L/min, and the same flow condition was applied during the PIV measurement. Through the comparisons, it was found that the experimental results were close to those obtained by CFD and had thus validated the CFD model, which could complement the limitation of the measurement in assessing the more detailed flow fields of the axial flow pump.     

Micro-scale Dynamic Simulation of Erythrocyte–Platelet Interaction in Blood Flow

Platelet activation, adhesion, and aggregation on the blood vessel and implants result in the formation of mural thrombi. Platelet dynamics in blood flow is influenced by the far more numerous erythrocytes (RBCs). This is particularly the case in the smaller blood vessels (arterioles) and in constricted regions of blood flow (such as in valve leakage and hinge regions) where the dimensions of formed elements of blood become comparable with that of the flow geometry. In such regions, models to predict platelet motion, activation, aggregation and adhesion must account for platelet–RBC interactions. This paper studies platelet–RBC interactions in shear flows by performing simulations of micro-scale dynamics using a computational fluid dynamics (CFD) model. A level-set sharp-interface immersed boundary method is employed in the computations in which RBC and platelet boundaries are tracked on a two-dimensional Cartesian grid. The RBCs are assumed to have an elliptical shape and to deform elastically under fluid forces while the platelets are assumed to behave as rigid particles of circular shape. Forces and torques between colliding blood cells are modeled using an extension of the soft-sphere model for elliptical particles. RBCs and platelets are transported under the forces and torques induced by fluid flow and cell–cell and cell–platelet collisions. The simulations show that platelet migration toward the wall is enhanced with increasing hematocrit, in agreement with past experimental observations. This margination is seen to occur due to hydrodynamic forces rather than collisional forces or volumetric exclusion effects. The effect of fluid shear forces on the platelets increases exponentially as a function of hematocrit for the range of parameters covered in this study. The micro-scale analysis can be potentially employed to obtain a deterministic relationship between fluid forces and platelet activation and aggregation in blood flow past cardiovascular implants.     

A Soft Computing-Based Analysis of Cutting Rate and Recast Layer Thickness for AZ31 Alloy on WEDM Using RSM-MOPSO

In the present research, the AZ31 alloy is machined by wire-cut electric discharge machining (WEDM). The experiments were designed according to the Box-Behnken design (BBD) of response surface methodology (RSM). The input process variables, namely servo feed (SF), pulse on-time (Ton), servo voltage (SV), and pulse off-time (Toff), were planned by BBD, and experiments were performed to investigate the cutting rate (CR) and recast layer thickness (RCL). The analysis of variance (ANOVA) was performed to determine the influence of machining variables on response characteristics. The empirical models developed for CR and RCL were solved using Multi-Objective Particle Swarm Optimization (MOPSO). Pareto optimal front is used for the collective optimization of CR and RCL. The optimal solution suggested by the hybrid approach of RSM-MOPSO is further verified using a confirmation test on the random setting indicated by the hybrid algorithm. It is found that the minimum RCL (6.34 µm) is obtained at SF: 1700; SV: 51 V; Toff: 10.5 µs; and Ton: 0.5 µs. However, maximum CR (3.18 m/min) is predicted at SF: 1900; SV: 40 V; Toff: 7 µs; and Ton: 0.9 µs. The error percentage of ±5.3% between the experimental results and predicted solutions confirms the suitability of the proposed hybrid approach for WEDM of AZ31.     

Accessing the syndemic of COVID-19 and malaria intervention in Africa

Background::The pandemic of the coronavirus disease 2019 (COVID-19) has caused substantial disruptions to health services in the low and middle-income countries...     

加用空肠内营养合中药滴注治疗重症急性胰腺炎的观察

目的:观察早期空肠内营养联合加味大承气汤颗粒肠内滴注治疗重症急性胰腺炎的疗效。方法:将66例符合纳入标准的重症急性胰腺炎患者随机分为2组,即观察组和对照组各33例。两组均予常规治疗,观察组在常规治疗的基础上采用早期空肠内营养联合加味大承气汤颗粒肠内滴注;对照组在常规治疗的基础上采用全胃肠外营养。分别监测并比较两组患者腹痛消失时间、住院天数、体重、血淀粉酶(AMY)、C-反应蛋白(CRP)、血浆白蛋白、前白蛋白值。结果:观察组AMY、CRP恢复正常时间、腹痛消失时间、平均住院天数较对照组明显缩短(P0.05),并发症发生率较对照组低(P0.05),白蛋白、前白蛋白、体重较对照组明显升高(P0.05)。结论:应用早期空肠内营养联合加味大承气汤颗粒肠内滴注能改善患者营养状况,减轻全身炎症反应,值得临床推广。     

紫癜颗粒对ITP模型小鼠骨髓细胞因子IL-3 TPO的影响

目的:通过观察ITP模型小鼠骨髓细胞白介素-3(IL-3)、血小板生成素(TPO)含量的变化,探讨IL-3、TPO含量变化与免疫性血小板减少性紫癜(ITP)发病之间的内在联系。方法:采用酶联免疫方法检测ITP模型小鼠骨髓细胞IL-3、TPO含量变化。结果:模型组小鼠骨髓细胞IL-3明显降低、TPO含量明显升高,均有统计学意义(P<0.05)。结论:调节巨核细胞的正性作用因IL-3与正性作用因子TPO参与了ITP的发病过程并发挥重要作用,紫癜颗粒通过调控骨髓细胞IL-3、TPO的含量变化而达到有效治疗ITP的目的。     

LPP低污染燃烧室两相喷雾燃烧数值研究

提出一种带有多点燃油直接喷射双环预混旋流(TAPS/MLDI)头部的贫油预混预蒸发(LPP)低污染圆筒燃烧室,为了获得该燃烧室两相喷雾燃烧流场与燃烧性能,利用Fluent数值研究三种LPP燃烧室头部方案和四种进口工况。计算结果表明:(1)LPP燃烧室头部冷态流场存在中心回流区、角落回流区和唇口回流区,流场结果与PIV试验结果吻合较好。(2)在头部方案不变的情况下,工况从100%推力下降到7%推力时,出口平均温度逐渐下降,污染物NO_x排放相应减少。(3)在进口工况不变时,头部方案B燃烧性能相对最优。(4)热力型NO_x的生成速率与燃气温度超过1950K区域的大小和最高燃气温度直接相关, 热力型NO_x的生成主要分布在火焰锋面附近。      

Formulation to target delivery to the ciliary body and choroid via the suprachoroidal space of the eye using microneedles

In this work, we tested the hypothesis that particles injected into the suprachoroidal space can be localized at the site of injection or broadly distributed throughout the suprachoroidal space by controlling polymeric formulation properties. Single hollow microneedles were inserted into the sclera of New Zealand White rabbits and injected non-biodegradable fluorescently tagged nanoparticles and microparticles suspended in polymeric formulations into the suprachoroidal space of the eye. When formulated in saline, the particles were distributed over 29–42% of the suprachoroidal space immediately after injection. To spread particles over larger areas of the choroidal surface, addition of hyaluronic acid to make moderately non-Newtonian solutions increased particle spread to up to 100% of the suprachoroidal space. To localize particles at the site of injection adjacent to the ciliary body, strongly non-Newtonian polymer solutions localized particles to 8.3–20% of the suprachoroidal space, which exhibited a small increase in area over the course of two months. This study demonstrates targeted particle delivery within the suprachoroidal space using polymer formulations that spread particles over the whole choroidal surface or localized them adjacent to the ciliary body after injection.     

消岩颗粒联合低分子肝素钠改善气虚血瘀型晚期非小细胞肺癌患者血液高凝状态的临床观察

[目的] 观察消岩颗粒联合低分子肝素钠对气虚血瘀型晚期非小细胞肺癌患者血液高凝状态的临床疗效。[方法] 收集2017年7月-2019年9月60例符合纳入标准的晚期气虚血瘀型非小细胞肺癌合并血液高凝状态患者，采取统计学随机分组方法分为治疗组与对照组，治疗组（消岩颗粒联合低分子肝素钠治疗）30例，对照组（低分子肝素钠治疗）30例。两组患者均采用抗凝治疗，即皮下注射低分子肝素钠5 000 U（每日1次），治疗组加用天津中医药大学第一附属医院院内制剂消岩颗粒（口服，每日两次），连续服用14 d，观察周期21 d为1个疗程，共观察2个疗程。观察两组治疗周期前后血清学D-二聚体定量、凝血指标[凝血酶原时间（PT）、活化部分凝血活酶时间（APTT）、纤维蛋白原（FIB）]、血小板（PLT）数量、中性粒-淋巴细胞比值（NLR）、中医症状积分、生活质量评分，以及血常规、肝肾功能等安全性指标，所得数据采用SPSS 19.0统计软件进行统计学分析并记录。[结果] 针对气虚血瘀型晚期非小细胞肺癌合并血液高凝状态患者，消岩颗粒联合低分子肝素钠可降低其血清学D-二聚体定量、NLR，改善乏力、肢体麻木症状，提高生活质量。[结论] 消岩颗粒联合低分子肝素钠可显著改善气虚血瘀型晚期非小细胞肺癌合并血液高凝状态患者的血液高凝状态，提高其生活质量，安全性较好。     

Design attributes of long-circulating polymeric drug delivery vehicles

Following systemic administration polymeric drug delivery vehicles allow for a controlled and targeted release of the encapsulated medication at the desired site of action. For an elevated and organ specific accumulation of their cargo, nanocarriers need to avoid opsonization, activation of the complement system and uptake by macrophages of the mononuclear phagocyte system. In this respect, camouflaged vehicles revealed a delayed elimination from systemic circulation and an improved target organ deposition. For instance, a steric shielding of the carrier surface by poly(ethylene glycol) substantially decreased interactions with the biological environment. However, recent studies disclosed possible deficits of this approach, where most notably, poly(ethylene glycol)-modified drug delivery vehicles caused significant immune responses. At present, identification of novel potential carrier coating strategies facilitating negligible immune reactions is an emerging field of interest in drug delivery research. Moreover, physical carrier properties including geometry and elasticity seem to be very promising design attributes to surpass numerous biological barriers, in order to improve the efficacy of the delivered medication.