Comparison Study of Different Drainage Tube Diameters with Negative Pressure Suction after Valve Replacement Surgery

Objective: This study aims to compare the effects of different drainage tube diameters (22F vs. 26F) combined with negative pressure suction on patients after valve replacement surgery, including postoperative indicators and complications. Methods: A total of 104 patients undergoing valve replacement surgery were included and divided into a 22F group (45 patients) and a 26F group (59 patients). The basic characteristics, postoperative ICU stay duration, drainage duration, postoperative complications, and pain scores were compared between the two groups. All data were analyzed using SPSS statistical software, with p Results: There were no significant differences between the two groups in terms of age, sex, and underlying diseases. The ICU stay duration and drainage duration showed no significant differences (p > 0.05). The total drainage volume in the 22F group was significantly lower than that in the 26F group (225 vs. 380 ml, p = 0.035), and the pain scores on the third postoperative day were also significantly lower in the 22F group (p Conclusion: Compared to the 26F group, patients in the 22F group exhibited less postoperative drainage volume and lower pain scores, suggesting that the 22F drainage tube may have better clinical outcomes after valve replacement surgery.

Earth Pressure Distribution and Sand Deformation Around Modified Suction Caissons(MSCs) Under Monotonic Lateral Loading

The modified suction caisson(MSC) is a novel type of foundation for ocean engineering, consisting of a short external closed-top cylinder-shaped structure surrounding the upper part of the regular suction caisson(RSC). The MSC can provide larger lateral bearing capacity and limit the deflection compared with the RSC. Therefore, the MSC can be much more appropriate to use as an offshore wind turbine foundation. Model tests on the MSC in saturated sand subjected to monotonic lateral loading were carried out to investigate the effects of external structure sizes on the sand surface deformation and the earth pressure distribution along the embedded depth. Test results show that the deformation range of the sand surface increases with the increasing width and length of the external structure. The magnitude of sand upheaval around the MSC is smaller than that of the RSC and the sand upheaval value around the MSC in the loading direction decreases with the increasing external structure dimensions. The net earth pressure in the loading direction acting on the internal compartment of the MSC is smaller than that of the RSC at the same embedded depth. The maximum net earth pressure acting on the external structure outer wall in the loading direction is larger than that of the internal compartment, indicating that a considerable amount of the lateral load and moment is resisted by the external skirt structure.

Impact of Impeller Stagger Angles on Pressure Fluctuation for a Double-Suction Centrifugal Pump

Pressure fluctuation may cause high amplitude of vibration of double-suction centrifugal pumps, but the impact of impeller stagger angles is still not well understood. In this paper, pressure fluctuation experiments are carried out for five impeller configurations with different stagger angles by using the same test rig system. Results show that the stagger angles exert negligible effects on the characteristics of head and efficiency. The distributions of pressure fluctuations are relatively uniform along the suction chamber wall, and the maximum pressure fluctuation amplitude is reached near the suction inlet tongue region. The pressure fluctuation characteristics are affected largely by impeller rotation, whose dominant frequencies include impeller rotation frequency and its harmonic frequencies, and half blade passage frequency. The stagger angle exerts a small effect on the pressure fluctuations in the suction chamber while a great effect on the pressure fluctuation in volute casing, especially on the aspect of decreasing the amplitude on blade passage frequency. Among the tested cases, the distribution of pressure fluctuations in the volute becomes more uniform than the other impeller configurations and the level of pressure fluctuation may be reduced by up to 50% when the impeller stagger angle is close to 24° or 360°.The impeller structure pattern needs to be taken into consideration during the design period, and the halfway staggered impeller is strongly recommended.

To investigate the clinical effect of modified closed negative pressure suction technique combined with flap transplantation on the treatment of deep chronic refractory wounds

Objective:To investigate the clinical effect of modified closed negative pressure suction technique combined with flap transplantation on the treatment of deep chronic refractory wounds.Methods:During March of 2015 to April of 2018,52 cases of patients with deep chronic refractory wounds were selected as research objects.They were divided into the control group and the treatment group by use of the random number table method,with 26 cases in each group.Among them,the control group was given conventional debridement combined with flap reconstruction,and the treatment group was treated with modified closed negative pressure suction technique combined with flap transplantation to observe the clinical effect.Results:(1)According to the analysis on the effect of flap transplantation,the excellent and good rate of the treatment group was 92.3%,and in the control group,it was 76.9%(p<0.05).(2)According to the statistics,the incidence of complications in the treatment group was lower than that in the control group(p<0.05).Conclusions:Modified closed negative pressure suction technique combined with flap transplantation has a good effect on the treatment of deep chronic refractory wounds with fewer complications.

Clinical application of flexible ureteroscopic sheath with controllable intraluminal pressure in treating ureteral stones

Objective:The purpose of the study was to assess the clinical efficacy and safety of a combined perfusion suction platform with pressure feedback control function and an ureteroscopic suction sheath that can measure the ureteropelvic pressure in implementing lithotripsies.Methods:Fifty-two patients who underwent lithotripsy under intelligent monitoring of ureteral intraluminal pressure from June 2016 to January 2018 were retrospectively recruited.The inclusion standard was stone diameter>1.5 cm but<2.5 cm.After the 12/14 Fr suction sheath was placed,manometer interface and suction interface of the sheath were connected to the platform via the pressure sensor and suction tube,respectively.The ureteroscope was connected to the platform perfusion pump,and the crushed stones were aspirated out under negative pressure.Results:According to the location of the stone,21(40.4%)cases were classified as upper ureteral stones,19(36.5%)were midureteral stones,and 12(23.1%)were lower ureteral stones.Forty-seven patients underwent successful primary sheath placement and lithotripsy with a mean operative time of 34.5(standard deviation 18.3)min.Retrograde stone migration did not occur.There were eight patients with hematuria postoperatively.Serious complication was 1.9% with one case of ureteral perforation.Stone clearance was 95.7% at Day 1e2 postoperatively,and 100% at Day 30 postoperatively.Conclusion:Ureteroscopic lithotripsy with intelligent pressure control using our device improved the efficiency of the lithotripsy and rate of stone clearance.The safety of the operation can be ensured.It is worth popularization and application in clinical practice.

Research on the Critical Buckling Pressure of Bucket Foundations with Inner Compartments for Offshore Wind Turbines

In the process of suction penetration of bucket foundations with inner compartments for offshore wind turbines,most researches focus on soil seepage failure and soil plugs,while the buckling of foundations is rarely investigated.Therefore,theoretical calculation methods for critical buckling pressures of the skirt and bulkheads of the bucket foundation are first presented according to the stability theory of a cylindrical shell and the small deflection theory of a thin plate,respectively.Furthermore,two types of models with and without considering the skirt-soil interaction are developed for the calculation of critical buckling pressure of the bucket foundation.Taking a practical project as an example,theoretical and numerical methods are used to obtain the critical buckling pressures of a bucket foundation.In this work,the theoretical method and the finite element model considering the skirt-soil interaction for calculating the critical buckling pressure of bucket foundations are firstly proposed.The results can help to optimize the design process of offshore wind turbine foundations and improve the safety of offshore wind power systems.

Long-term decay of the water pressure in the osmotic tensiometer

Matric suction is an important state variable required for the assessment of unsaturated soil properties.Tensiometers are commonly used for direct matric suction measurement but have a limited measuring range up to 90 kPa due to the cavitation problem.Osmotic tensiometer(OT)can improve the measuring range of tensiometers by increasing the osmotic pressure of water to avoid the cavitation.However,the long-term water pressure decay that appeared in OTs caused a gradual decrease in their measuring range.In this study,crosslinked poly(acrylamide-co-acrylic acid)potassium salt(PAM-co-PAAK)was used for the preparation of OTs(five in total)to explore the mechanism of water pressure decay of OTs.The maximum water pressure in the OT versus the volume fraction of polymer filled in the OT was described based on the Flory-Huggins polymer theories and validated using WP4C dewpoint hygrometer.The long-term pressure decay of OT-1,OT-2,and OT-3 was observed for 130 d and constant pressures were found for OT-1 and OT-2,indicating that the pressure decay of OT was mainly caused by the stress relaxation of the polymer hydrogels,and standard linear solid(SLS)rheological model was appropriate to fit the decay data.For OT-1,OT-2 and OT-3,the theoretical osmotic pressure that was calculated based on the mass of retrieved polymer from OTs after 130-d pressure observation was higher than the actual osmotic pressure as observed,indicating that polymer leakage cannot explain the pressure decay of the OT.The ultravioletevisible(UVevisible)spectrophotometry examined the change in polymer concentrations in the water containers of OT-4 and OT-5 and demonstrated that there was no increase in polymer leakage during the period of pressure decay of OT-4 and OT-5.As a result,the pressure decay of OT was not caused by polymer leakage.The results of this research suggested that the viscoelastic properties of polymers should be taken into consideration in further OT development.

Earth Pressure of Retaining Structure Induced by Subgrade under Rainfall

This article selects the retaining wall as the research object, introducing the rainfall infiltration model, considering the infiltration of rainwater into the groundwater recharge, analysizing the variation of earth pressure in the subgrade retaining wall. On this occasion, the back of retaining wall produces stable seepage water and compares with the non drainage water body. The results show that, with the infiltration of rainwater into the groundwater recharge, the greater the active earth pressure under the condition of rainfall appears, more quickly the active earth pressure of the retaining wall with the drainage body increases. The matrix suction of unsaturated soils, which is infiltrated into soil of subgrade, has a positive effect on the shear strength of the earth pressure.

环锭细纱机负压吸风系统分析与改善

为了有效降低环锭细纱机长车负压吸风系统的负压差,降低运转能耗,对环锭细纱机负压吸风系统进行分析并改善,对比了不同风管截面的吸风效果,并对风管单侧吸风与风管双侧吸风中间断开、双侧吸风中间连通等3种吸风方式进行对比试验。结果表明:适当加大风管截面配以不同口径风管接头的局部调整,采用头尾双吸风风道中间连通的吸风方式可有效平衡全机负压,满足环锭细纱机长车负压吸风系统需求,且能耗相对较低。认为:在改善吸风系统的基础上做好日常车间管理,可达到更好的吸风和节能效果。

正负压序贯冲吸装置的设计与应用

目的:设计正负压序贯冲吸装置,并测试其在疏通鼻肠管堵管中的应用效果。方法:该装置主要包括正压冲洗部分、负压吸引部分、三通转接头和精准疏通器。正压冲洗部分包括正压冲洗装置、正压压力调节器、压力传感器、加压软袋等;负压抽吸部分包括负压吸引装置、负压压力调节器、负压表、负压瓶等。正压冲洗部分中的加压软袋为中空圆柱形,内层材料为普通聚氯乙烯,外层材料为丙烯腈-苯乙烯-丁二烯共聚物。选取发生鼻肠管堵管的60例患者,随机将其分为对照组和观察组各30例,对照组采用10 mL注射器,观察组采用正负压序贯冲吸装置,均予38~40℃温水疏通,比较2组的疏通效果、堵管疏通所需时间、营养支持天数及费用。采用SPSS 22.0软件对数据进行统计学分析。结果:观察组疏通总有效率(93.3%)高于对照组(73.4%),疏通效果优于对照组,鼻肠管堵管疏通时间、营养支持天数及费用[(7.63±4.97)min、(10.07±3.07)d、(3 180±260)元]少于对照组[(10.73±4.57)min、(13.03±4.05)d、(4 550±660)元],差异有统计学意义(P均<0.05)。结论:正负压序贯冲吸装置可以有效提升鼻肠管堵管疏通效果、缩短堵管疏通所需时间、减少营养支持天数及费用,具有一定实用价值。

H-M Bearing Capacity of A Modified Suction Caisson Determined by Using Load-/Displacement-Controlled Methods

This paper presents a series of monotonically combined lateral loading tests to investigate the bearing capacity of the MSCs （modified suction caissons） in the saturated marine fine sand. The lateral loads were applied under load- and displacement-controlled methods at the loading eccentricity ratios of 1.5, 2.0 and 2.5. Results show that, in the displacement-controlled test, the deflection-softening behavior of load-deflection curves for MSCs was observed, and the softening degree of the load-deflection response increased with the increasing external skirt length or the decreasing loading eccentricity. It was also found that the rotation center of the MSC at failure determined by the load-controlled method is slightly lower than that by the displacement-controlled method. The calculated MSC capacity based on the rotation center position in serviceability limit state is relatively conservative, compared with the calculated capacity based on the rotation center position in the ultimate limit state. In the limit state, the passive earth pressures opposite the loading direction under load- and displacement-controlled methods decrease by 46% and 74% corresponding to peak values, respectively; however, the passive earth pressures in the loading direction at failure only decrease by approximately 3% and 7%, compared with their peak values.

Slow-pull and different conventional suction techniques in endoscopic ultrasound-guided fine-needle aspiration of pancreatic solid lesions using 22-gauge needles

AIM To evaluate the cytological diagnostic capacity and sample quality of the slow-pull technique and compare them with different suction techniques.METHODS From July 2010 to December 2015, 102 patients with pancreatic solid lesions who underwent endoscopic ultrasound-guided fine-needle aspiration(EUS-FNA) with 22-gauge needles were retrospectively evaluated. EUS-FNA diagnosis was based on a cytological examination, and final diagnosis was based on a comprehensive standard of cytological diagnosis, surgical pathology and clinical or imaging follow-up. Cytological specimens were characterized for cellularity and blood contamination. The cytological diagnostic capacity and sample quality of the slow-pull technique and suction techniques with 5-m L/10-m L/20-m L syringes were analyzed.RESULTS Of all of the EUS-FNA procedures, the slow-pull technique and suction techniques with 5-m L/10-m L/20-m L syringes were used in 31, 19, 34 and 18 procedures, respectively. There were significant differences between these four suction techniques in terms of cytological diagnostic accuracy(90.3% vs 63.2% vs 58.8% vs 55.6%, P = 0.019), sensitivity(88.2% vs 41.7% vs 40.0% vs 36.4%, P = 0.009) and blood contamination(score ≥ 2 for 29.0% vs 52.6% vs 70.6% vs 72.2%, P = 0.003). The accuracy and sensitivity of the slow-pull technique were significantly higher than those of the suction techniques using 5-m L(P = 0.03, P = 0.014), 10-m L(P = 0.005; P = 0.006) and 20-mL syringes(P = 0.01, P = 0.01). Blood contamination was significantly lower in the slow-pull technique than in the suction techniques with 10-m L(P = 0.001) and 20-mL syringes(P = 0.007).CONCLUSION The slow-pull technique may increase the cytological diagnostic accuracy and sensitivity with slight blood contamination during EUS-FNA when using 22-gauge needles for solid pancreatic masses.

Characteristic Test Study on Bearing Capacity of Suction Caisson Foundation Under Vertical Load

Suction caisson foundations are often subjected to vertical uplift loads,but there are still no wide and spread engineering specifications on design and calculation method for uplift bearing capacity of suction caisson foundation.So it is important to establish an uplift failure criterion.In order to study the uplift bearing mechanism and failure mode of suction caisson foundation,a series of model tests were carried out considering the effects of aspect ratio,soil permeability and loading mode.Test results indicate that the residual negative pressure at the top of caisson is beneficial to enhance uplift bearing capacity.The smaller the permeability coefficient is,the higher the residual negative pressure will be.And the residual negative pressure is approximately equal to the water head that causes seepage in the caisson.When the load reaches the ultimate bearing capacity,both the top and bottom negative pressures are smaller than Su and both the top and bottom reverse bearing capacity factors are smaller than 1.0 in soft clay.Combined the uplift bearing characteristics of caisson in sandy soil and soft clay,the bearing capacity composition and the calculation method are proposed.It can provide a reference for the engineering design of suction caisson foundation under vertical load.

Penetration Resistance of Skirt-Tip with Rough Base for Suction Caissons in Clay

Suction caissons can readily penetrate into the seabed under the combination of the self-weight and suction resulted from the encased water being increasingly pumped out. During suction-assisted penetration, the equivalent overburden at the skirt-tip level outside the caisson is generally higher than that inside because the vertical stress within the soil plug is reduced by the exerted suction. This may result in a uniform shear stress developing over the base of the skirt-tip as the soil below the skirt-tip tends to move into the caisson, which leads to an asymmetric failure wedge existing below the base of the skirt-tip. Besides, different adhesion factors along the inside(αi) and outside(αo) of the skirt wall will cause asymmetric plastic zones inside and outside the caisson. Accordingly, an asymmetric failure mechanism is therefore proposed to calculate the penetration resistance of the skirt-tip. The proposed failure mechanism is the first to consider the effect of different adhesion factors(αi) and(αo) on the failure mechanism at the skirt-tip, and involves the contribution from the weighted average of equivalent overburdens inside and outside caisson at the skirt-tip level. The required suction pressure can be obtained in terms of force equilibrium of the caisson in a vertical direction. Finally, the asymmetric failure mechanism at the skirt-tip is validated with the FE calculations. By comparing with the measured data, the predictions of the required suction pressure are found to be in good agreement with the experimental results.

Pressure Measurement on Suction Surface of a Single Vane Using Pressure-sensitive Paint

Global pressure distribution on the suction surface of a single vane in a transonic cascade wind tunnel is measured with the help of intensity-based pressure-sensitive paint (PSP) technique using a type of temperature-insensitive fluorescent paint and a self-made measurement system. This measurement is conducted at the outlet of the cascade wind tunnel at the Mach numbers 0.3 and 0.4, attack angle about –20°, ambient pressure 95.4 kPa and temperature 15 °C. The vane under study owns a large camber angle of ...

可控负压吸引下输尿管软镜钬激光碎石术治疗肾结石合并尿路感染的疗效分析

目的 分析肾结石且伴有尿路感染患者应用可控负压吸引下输尿管软镜钬激光碎石术治疗的临床效果。方法 80例肾结石合并尿路感染患者,将样本经随机法分为实验组和对照组,每组40例。对照组患者接受常压输尿管软镜钬激光碎石术治疗,实验组患者接受可控负压吸引下输尿管软镜钬激光碎石术治疗。比较两组患者术后住院时间、术后血尿时间、手术时间、术后结石清除率及术后感染发生情况。结果 实验组患者的术后住院时间(2.55±1.45)d、术后血尿时间(1.13±0.56)d、手术时间(42.30±4.24)min明显短于对照组的(4.00±2.35)d、(2.20±0.65)d、(63.03±6.33)min(P<0.05)。实验组患者的术后感染发生率为12.5%(5/40),相比于对照组的40.0%(16/40)低(P<0.05),手术更安全、可靠。实验组患者的术后结石清除率97.5%(39/40)显著高于对照组的82.5%(33/40)(P<0.05),术后残石率更低。结论 可控负压吸引下输尿管软镜钬激光碎石术应用于肾结石合并尿路感染治疗中,能够有效缩短住院时间及手术时间,提高术后结石清除率,降低患者术后发热发生率,安全有效。

高速轴向柱塞泵空化机制研究与优化

为降低高速轴向柱塞的空化程度,以某型号轴向柱塞泵为例,利用Pumplinx软件搭建CFD仿真模型,探究不同转速与不同吸油口压力对泵空化程度的影响,并结合MATLAB软件对离散的仿真结果进行拟合,得到转速、吸油口压力与吸油效率的变化规律曲线。研究结果表明:当柱塞腔内气体体积达到12%以上,柱塞泵吸油效率下降甚至无法吸油;通过提高吸油口压力可以有效降低柱塞腔的空化程度,提高柱塞泵吸油效率;为了保证泵在5000~6000 r/min下能够正常吸油且有较高的吸油效率,可以使吸油口压力值介于0.25~0.30 MPa之间,此时柱塞腔空化程度和吸油效率均达到相对稳定。

双吸泵交错叶轮内流诱导噪声

为研究叶轮交错布置对双吸泵内流噪声的影响,根据叶片夹角设计了4组叶轮交错方案.在设计工况下,采用标准k-ε湍流模型对双吸泵内部流动进行了非定常数值模拟,基于数值模拟结果提取偶极子声源,应用直接声学边界元法计算了双吸泵内声场,分析了不同叶轮交错方案对泵能量性能、压力脉动和内流噪声等的影响规律.研究结果表明:叶轮交错布置能够提高双吸泵能量性能,扬程和效率最高分别提升3.0%和5.7%;随着交错角度增大,压力脉动峰峰值逐渐减小,最大降幅达79.6%;当交错角为叶轮夹角的1/2时,蜗壳内流场压力脉动、偶极子声源流动噪声和声压频响曲线的主频均从1倍叶频变为2倍叶频,且主频处幅值明显降低;随着交错角增大,吸水室、叶轮和蜗壳表面高声压区范围逐渐减小,表面声压最大值和声压频响曲线逐渐降低,最大降幅分别为9.9%和18.7%.研究结果可为双吸泵优化设计和减振降噪提供一定的理论参考.

消痔灵灌注联合负压抽吸治疗腋臭的效果

目的观察并比较单一负压抽吸术与负压抽吸联合消痔灵灌注治疗腋臭的临床疗效及并发症发生情况,探讨联合治疗对腋臭患者异味程度和生活质量的影响。方法选取收治的81例首次治疗腋臭的患者,随机分为负压抽吸组(39例)与联合治疗组(42例)。抽吸组给予单一负压抽吸术治疗,联合治疗组给予负压抽吸联合消痔灵灌注治疗。比较2种治疗方法的临床疗效及并发症发生情况。结果术后随访3~6个月,负压抽吸组的伤口愈合时间长于联合治疗组(P<0.05);负压抽吸组的总有效率(84.62%)低于联合治疗组(100.00%),P<0.05;负压抽吸组的并发症总发生率(26.92%)高于联合治疗组(13.10%),P<0.05;负压抽吸组患者的生活质量评分显著低于联合治疗组(P<0.05)。结论消痔灵灌注联合负压抽吸对于腋臭的治疗效果优于单一负压抽吸治疗,且能显著降低并发症的发生,减轻腋臭患者的异味程度,改善其生活质量。

不同气道准备方式在ICU患者紧急气管插管中的应用效果

目的观察负压吸引牙刷在ICU患者紧急气管插管气道准备中的应用效果。方法95例在ICU需行紧急气管插管患者,按照随机数字表法分为对照组47例(UE视频喉镜)和试验组48例(负压吸引牙刷进行气道准备联合UE视频喉镜)。比较两组插管情况、气管插管并发症、炎性指标、麻醉准备时间与插管总时间。结果试验组暴露声门的平均时间、插管尝试次数、气管插管时间与对照组比较差异有统计学意义(P<0.05),两组首次气管插管成功率与气管插管并发症发生率比较,差异无统计学意义(P>0.05);试验组炎性指标C-反应蛋白、降钙素原均低于对照组(P<0.05),麻醉准备时间与插管总时间短于对照组(P<0.05)。结论ICU患者使用UE视频喉镜经口气管插管前先行使用负压吸引牙刷进行气道准备,更能快速清理气道分泌物,缩短暴露声门的平均时间,有助于判断麻醉准备效果,更容易辅助视频喉镜快速完成经口气管插管。