Effects of diamond particle size on microstructure and properties of diamond/Al-12Si composites prepared by vacuum-assisted pressure infiltration

Diamond/aluminium composites have attracted attention in the field of thermal management of electronic packaging for their excellent properties.In order to solve the interfacial problem between diamond and aluminium,a novel process combining pressure infiltration with vacuum-assisted technology was proposed to prepare diamond/aluminum composites.The effect of diamond particle size on the microstructure and properties of the diamond/Al-12Si composites was investigated.The results show that the diamond/Al-12Si composites exhibit high relative density and a uniform microstructure.Both thermal conductivity and coefficient of thermal expansion increase with increasing particle size,while the bending strength exhibits the opposite trend.When the average diamond particle size increases from 45μm to 425μm,the thermal conductivity of the composites increases from 455 W·m^(-1)·K^(-1)to 713 W·m^(-1)·K^(-1)and the coefficient of thermal expansion increases from 4.97×10^(-6)K^(-1)to 6.72×10^(-6)K^(-1),while the bending strength decreases from 353 MPa to 246 MPa.This research demonstrates that high-quality composites can be prepared by the vacuum-assisted pressure infiltration process and the thermal conductivity of the composites can be effectively improved by increasing the diamond particle size.

Clinical efficacy of endovascular revascularization combined with vacuum-assisted closure for the treatment of diabetic foot

BACKGROUND The diabetic foot is a common cause of disability and death,and comorbid foot infections usually lead to prolonged hospitalization,high healthcare costs,and a significant increase in amputation rates.And most diabetic foot trauma is complicated by lower extremity arteriopathy,which becomes an independent risk factor for major amputation in diabetic foot patients.AIM To establish the efficacy and safety of endovascular revascularization(ER)combined with vacuum-assisted closure(VAC)for the treatment of diabetic foot.METHODS Clinical data were collected from 40 patients with diabetic foot admitted to the Second Affiliated Hospital of Soochow University from April 2018 to April 2022.Diabetic foot lesions were graded according to Wagner’s classification,and blood flow to the lower extremity was evaluated using the ankle-brachial index test and computerized tomography angiography of the lower extremity arteries.Continuous subcutaneous insulin infusion pumps were used to achieve glycemic control.Lower limb revascularization was facilitated by percutaneous transluminal balloon angioplasty(BA)or stenting.Wounds were cleaned by nibbling debridement.Wound granulation tissue growth was induced by VAC,and wound repair was performed by skin grafting or skin flap transplantation.RESULTS Of the 35 cases treated with lower limb revascularization,34 were successful with a revascularization success rate of 97%.Of these,6 cases underwent stenting after BA of the superficial femoral artery,and 1 received popliteal artery stent implantation.In the 25 cases treated with infrapopliteal artery revascularization,39 arteries were reconstructed,7 of which were treated by drug-coated BA and the remaining 32 with plain old BA.VAC was performed in 32 wounds.Twenty-four cases of skin grafting and 2 cases of skin flap transplantation were performed.Two patients underwent major amputations,whereas 17 had minor amputations,accounting for a success limb salvage rate of 95%.CONCLUSION ER in combination with VAC is a safe and effective treatment for diabetic foot that can significantly improve limb salvage rates.The use of VAC after ER simplifies and facilitates wound repair.

Percutaneous Removal of Benign Breast Lesions with an Ultrasound-guided Vacuum-assisted System:Influence Factors in the Hematoma Formation

Objective To explore the influence factors in hematoma formation after removing benign breast lesions with an ultrasound-guided vacuum-assisted system.Methods A total of 232 females with 312 benign breast masses received excisional biopsy with ultrasoundguided vacuum-assisted system.The pathology of patients,results of hematoma development and outcome,influence factors for hematoma occurrence(nodule size,nodule location,number of nodule,breast shape,menstrual period,efficacy time of bandage,and application of hemostatic agents during the procedure) were recorded.Results Pathologic examination revealed fibroadenomas in 138 lesions,fibroadenosis in 127 lesions,intraductal papillomas in 39 lesions,inflammatory change in 4 lesions,retention cyst of the breast in 3 lesions,and benign phyllodes tumor in 1 lesion.Thirty hematomas were observed in patients(9.6%).Finally,97.0%hematomas were absorbed completely within 6 months follow-up.The incidence rates of hematoma were increased by 24.7%,10.0%,63.2%,13.9%in the nodule diameter larger or equal to 25 mm group,removal of larger or equal to two nodules once time from one patient group,menstrual period group,and larger and loose breast group,respectively(all P<0.05).However,the incidences were decreased by 60.6%in the bandage performed for 12-24 hours or beyond 24 hours group(P<0.05).The multiple logistic regression models revealed that nodule size(x^2=15.227,P<0.001),number of nodule(x^2=7.767,P=0.005),menstrual period(x^2=24.530,P<0.001),and breast shape(x^2=9.559,P=0.002) were independent risk factors associated with hematoma occurrence,but efficacy time of bandage was a protective factor associated with hematoma occurrence.Conclusion The occurrence of hematoma after the minimally invasive operation was associated with nodule size,number of nodule,menstrual period,breast shape,and efficacy time of bandage.

Highly efficient flexible perovskite solar cells with vacuum-assisted low-temperature annealed SnO2 electron transport layer

The demand for lightweight, flexible, and high-performance portable power sources urgently requires high-efficiency and stable flexible solar cells. In the case of perovskite solar cells(PSCs), most of the common electron transport layer(ETL) needs to be annealed for improving the optoelectronic properties,while conventional flexible substrates could barely stand the high temperature. Herein, a vacuumassisted annealing SnO_(2) ETL at low temperature(100℃) is utilized in flexible PSCs and achieved high efficiency of 20.14%. Meanwhile, the open-circuit voltage(V_(oc)) increases from 1.07 V to 1.14 V. The flexible PSCs also show robust bending stability with 86.8% of the initial efficiency is retained after 1000 bending cycles at a bending radius of 5 mm. X-ray photoelectron spectroscopy(XPS), atomic force microscopy(AFM), and contact angle measurements show that the density of oxygen vacancies, the surface roughness of the SnO_(2) layer, and film hydrophobicity are significantly increased, respectively. These improvements could be due to the oxygen-deficient environment in a vacuum chamber, and the rapid evaporation of solvents. The proposed vacuum-assisted low-temperature annealing method not only improves the efficiency of flexible PSCs but is also compatible and promising in the large-scale commercialization of flexible PSCs.

Is sentinel lymph node biopsy necessary for the patients diagnosed with breast ductal carcinoma in situ using core needle biopsy or vacuum-assisted biopsy as the initial diagnostic method？

Axillary lymph node status is one of the most important prognostic indicator of survival for breast cancer, especially in ductal carcinoma in situ （DCIS）. The purpose of this study was to investigate whether sentinel lymph node biopsy （SLNB） should be performed in patients with an initial diagnosis of DCIS. Methods： A retrospective study was performed of 124 patients with an initial diagnosis of DCIS between March 2000 and June 2014. The patients were treated with either SLNB or axillary node dissection during the surgery, and we compared the clinicopathologic characteristics, image features, and immunohistochemical results. Results： Eighty-two patients （66.1%） had pure DCIS and 25 （20.2%） had DCIS with microinvasion （DCISM）, 17 （13.7%） updated to invasive breast cancer （IBC）. 115 patients （92.7%） underwent SLNB, among them, 70 patients （56.5%） underwent axillary node dissection. 3 of 115 patients （2.6%） had a positive sentinel lymph node, only 1 （1.4%） of 70 patients had axillary lymph node metastasis, in 84 patients （66.7%） who were diagnosed DCIS by core needle biopsy （CNB） and vacuum-assisted biopsy （VAB）. 26 patients （31.0%） were upstaged into IBC or DCISM in the final histological diagnosis. The statistically significant factors predictive of underestimation were large tumor size, microcalcifications, comedo necrosis, positive Her-2 status, negative estrogen receptor status. Conclusion： The metastasis of sentinel lymph nodes in pure DCIS is very low, but the underestimation of invasive carcinoma in patients with an initial diagnosis of DCIS is an usual incident, especially in the cases when DCIS is diagnosed by CNB or VAB. Our findings suggest patients presenting with a preoperative diagnosis of DCIS associated with large tumor sizes, microcalcifications, comedo necrosis, positive Her-2 status, negative ER status are more likely to be DCISM and IBC in final diagnosis. SLNB should be performed in this part of patients.

New Wireless Handheld Ultrasound-Guided Vacuum-Assisted Breast Biopsy (VABB) Devices: An Important Innovation in Breast Diagnosis

Vacuum-assisted breast biopsy (VABB) plays a fundamental role in the preoperative assessment of breast lesions pro- viding large histology samples that are useful to define diagnoses and biological parameters to guide treatment planning. This technique has been used in our institute since 2000 and two new wireless handheld ultrasound-guided VABB de- vices have been introduced since May 2012. In this report we analyze our experience with these revolutionary devices which are able to provide the option of single-insertion contiguous tissue samples respectively with a 13/14-gauge aperture. Our initial experience on 75 lesions shows that these devices are safe, fast, procedurally advantageous for operators and well accepted by patients. Finally VABB procedures can markedly reduce the need for surgical biopsy.

Diagnosis and excision of breast multi-focal lesions by ultrasound-guided vacuum-assisted biopsy:a comparative evaluation

Objective To compare and evaluate the efficacy of diagnosis and excision for appropriately selected breast multi-focal lesions and solitary lesion by ultrasound-guided vacuum-assisted biopsy(UGVAB).Methods Among 392 appropriately selected patients,187 patients with multi-focal lesions and 205 patients with solitary lesion were treated by the 8-gauge UGVAB from May 2007 to June 2009.All lesions were removed as completely as possible.The patients with benign pathology underwent physical and ultrasound examinations at one week and 6 months after procedure.Results During the procedure,only three patients had vasovagal syncope and twenty others complained of other intraoperative discomfort.An accurate pathological diagnosis was obtained in all lesions.There was no apparent false-negative result among the 696 lesions with benign pathology at a follow-up of 6 months after procedure.The rates of malignant or premalignant pathology,postoperative complications and residual lesions in patients with multi-focal lesions were higher than those in patients with solitary lesion.If each lesion was considered as a subject of study,there was no significant difference between the two groups.Conclusion UGVAB is an effective method for diagnosis and excision of appropriately selected breast multi-focal lesions and can be used routinely.

Efficacy and prognosis of vacuum-assisted excision for benign intraductal papilloma of breast:A meta-analysis

Objective:To evaluate the safety and effectiveness of vacuum-assisted excision for benign intraductal papilloma of breast.Methods:The databases including PubMed,Embase,Cochrane Library,WangFang,CNIK,VIP and Web of Science were searched by computer,according the inclusion and exclusion criteria after screening of literature.The Cochrane handbook and Newcastle-Ottawa scale was used to evaluate the studies.Then the Review Manager 5.3 software was to used analyze the data.Results:A total of 1016 patients was included in 9 articles.The amount of blood loss in vacuum-assisted surgery was less than that in open surgery[MD=-6.38,95%CI(-9.90,-2.86),P<0.05].The drainage[MD=-2.56,95%CI(-4.97,-0.15,P<0.05]and drainage time[MD=-0.25,95%CI(-0.40,-0.09),P<0.05]in vacuum-assisted surgery was less than that in open surgery.There were also few postoperative complications than that in open surgery[RR=0.43,95%CI(0.29,0.64),P<0.05].Compared with open surgery,the postoperative recurrence rate was lower in vacuum-assisted surgery[RR=0.26,95%CI(0.14,0.49),P<0.05].Last,there was no statistically significant difference in the operative time between vacuum-assisted surgery and open surgery,[SD=-12.82,95%CI(-25.70,0.06),P=0.05].Conclusion:Compared with open surgery,vacuum-assisted excision has the advantages of less blood loss and lower postoperative complications,but the operative time is not statistically significant compared with open surgery.In addition,compared with open surgery in this study,vacuum-assisted excision has the advantages of lower recurrence rate,but it still needs long-term dynamic observation.

Efficacy and Safety of Ultrasound Guided Vacuum-Assisted Excision of Fibroadenomas: A Systematic Review

Background: Ultrasound-guided, vacuum-assisted excision [UGVAE] of fibroadenomas is an emerging minimally invasive procedure. UGVAE is being increasingly employed by breast radiologists and surgeons. It has been approved for this use since 2006 by the National Institute for Health and Clinical Excellence in the UK. The aim of this systematic review is to evaluate the efficacy and safety of this procedure based on the up to date available evidence. Methods: A comprehensive literature search of the Cochrane library, Medline, Embase, PubMed, Google scholar, Trip-database, Internet, and the reference lists of relevant articles was performed. We searched for literature with sizeable cases of therapeutic vacuum-assisted excision of fibroadenomas. All prospective studies with more than 20 study participants were screened. The study quality was assessed using the Grading of Recommendations Assessment, Development, and Evaluation [GRADE] approach. All were in English. Results: Of the four case series that fulfilled the inclusion criteria there were 516 patients in which 520 procedures were performed. Overall complete excision rate was 89.4%. In two of the studies, this was 100% when the lesions were less than 1.5 cm but reduced to 61% when between 1.5 and 2 cm. Most common significant complication was bleeding with 2 cases of pneumothorax. None of the studies can be regarded as high quality going by GRADE approach. Conclusion: Within the limit of the current published case series, UGVAE appears to be an effective and safe procedure for excision of small fibroadenomas of less than 15 mm in size. A well designed case control study or randomized controlled trials with a sufficient sample size is needed to further assess its safety, effectiveness and more importantly, patients’ satisfaction especially in larger sized fibroadenomas.

Comparison of the underestimation rate in cases with ductal carcinoma in situ at ultrasound-guided core biopsy: 14-gauge automated core-needle biopsy vs 11-gauge vacuum-assisted biopsy

Objective： The objective of this study was to compare the underestimation rate of invasive carcinoma cases with ductal carcinoma in situ （DCIS） at percutaneous ultrasound-guided core biopsies of breast lesions between 14-gauge automated core needle biopsy （ACNB） and 11-gauge vacuum-assisted biopsy （VAB）, and analyze the diagnostic advantages and insufficiencies in DCIS between this two methods, and to determine the relationship between the lesion type （masses or microcalcifications on radiological findings ） and DCIS underestimation rate. Methods： We collected 152 breast lesions which were diagnosed as DCIS by retrospectively reviewing data about ultrasound-guided biopsies of breast lesions （from February 2003 to July 2010）. There were 98 lesions in 95 patients by 14-gauge ACNB, and 54 lesions in 52 patients by 11-gauge VAB （The system used in this study called Mammatome, MMT）. The clinical and radiological findings were reviewed; meanwhile all the selected patients had histological results of the biopsies and follow-up surgeries which also achieved the reliable pathological results to compare with the biopsy results. The differences between two correlated histological results defined as underestimation, and the histological DCIS underestimation rates were compared between the two groups. According to the radiological characteristics, each group was classified into two subgroups （masses or micrecalcifications group）, and the differences between subgroups were also analyzed. Results： The DCIS underestimation rate was 45.9% （45/98） for 14-gauge ACNB and 16.6% （9/54） for MMT. According to the lesion type on ultrasonography, DCIS underestimation was 31.0% （26/84） in masses （43.1% using ACNB and 12.1% using MMT; P = 0.003） and 42.6% （29/68） in microcalcifications （48.9% using ACNB and 23,8% using MMT; P = 0,036）, Conclusion： The underestimation rate of invasive carcinoma in cases with DCIS at ultrasound-guided core biopsies is significantly higher for ACNB than for MMT. Furthermore, this difference does not alter among the two lesion types presented on ultrasonography. So ultrasound-guided VAB （MMT system） could be an effective and useful method for the diagnosis of DCIS lesions no matter what the lesion type is.

真空辅助乳腺微创旋切术治疗乳腺纤维腺瘤的临床效果研究

目的:探讨真空辅助乳腺微创旋切术治疗乳腺纤维腺瘤的临床效果。方法:选取笔者医院2019年9月-2020年9月收治的92例乳腺纤维腺瘤患者,随机分为观察组(n=46,应用真空辅助乳腺微创旋切术)和对照组(n=46,应用环乳晕切口术),采用统计学方法分析两组患者治疗后的围术期指标(手术时间、术中出血量、切口长度、切口愈合时间)、美学效果(乳房对称性、凹陷程度、质地与弹性、皮肤颜色)、乳晕区感觉神经功能损伤情况、并发症(乳房变形、皮下血肿、皮肤破损、皮下瘀斑)、肿瘤复发率及肿瘤残余率。结果:术后,观察组手术时间、切口愈合时间短于对照组,术中出血量少于对照组,切口长度短于对照组,差异均有统计学意义(P<0.05);术后1个月,观察组美学效果优良率高于对照组患者(P<0.05);观察组患者术后1 d与术后6个月乳晕区感觉神经功能正常的比例为43.48%、91.30%,均高于对照组的23.91%、73.91%(P<0.05);术后,观察组肿瘤残余率和复发率均低于对照组(P<0.05),两组并发症发生情况比较差异无统计学意义(P>0.05)。结论:真空辅助乳腺微创旋切术能够降低围术期指标和术后并发症,美学效果好,肿瘤残余率和复发率低,值得临床推广应用。

经乳晕切口真空辅助微创旋切系统治疗乳腺良性肿瘤的临床效果

目的探讨经乳晕切口真空辅助微创旋切系统治疗乳腺良性肿瘤的临床效果。方法选取2022年1月至12月淄博市妇幼保健院乳腺甲状腺外科收治的100例乳腺良性肿瘤患者为研究对象,按照奇偶数法分为两组,每组50例。参比组采用传统开放手术治疗,观察组采用经乳晕切口真空辅助微创旋切系统治疗,比较两组的治疗效果。结果观察组手术时间短于参比组,出血量少于参比组,手术切口长度短于参比组(P<0.05);观察组术后疼痛时间、切口愈合时间、住院时间短于参比组(P<0.05);观察组并发症总发生率低于参比组(P<0.05)。结论经乳晕切口真空辅助微创旋切系统治疗乳腺良性肿瘤的临床效果显著,值得推广。

孔槽泡沫夹芯复合材料真空辅助树脂传递工艺仿真与优化

本工作提出了孔槽泡沫夹芯复合材料的设计方案并针对真空辅助树脂传递(VARI)工艺进行了实验和仿真研究。首先,通过实验测得玻璃纤维织物和树脂的相关参数,利用Hagen-Poiseuill方程和达西定律算出孔洞和沟槽的等效渗透率;接着,利用PAM-RTM模拟孔槽泡沫夹芯复合材料的VARI工艺过程,并与实验结果进行对比;然后,使用PAM-RTM研究了芯材加工参数、树脂灌注方式和导流网铺敷区域对成型过程的影响,并选出了最优方案;最后,在此方案的基础上研究了树脂黏度与灌注时间的关系,并拟合得到了预测函数。结果表明:实验结果与仿真结果基本一致;最优灌注方案可显著缩短树脂填充时间并降低整体孔隙率;预测函数可准确预测灌注时间,对实际生产具有一定的指导意义。

响应面分析法优化减压热脱附技术处理油基钻屑

采用减压热脱附技术处理油基钻屑,考察了热脱附温度、热脱附时间和系统真空压力对脱油率的影响,在此基础上,采用响应面分析法建立了各因素与脱油率之间关系的数学模型,优化了工艺参数。实验结果表明,在热脱附温度350~450℃、系统真空压力-0.07~-0.09 MPa、热脱附时间60~90 min的条件下,脱油率可达98%以上。各因素对脱油率的影响依次为热脱附温度>系统真空压力>热脱附时间;在热脱附温度420℃、系统真空压力-0.08 MPa、热脱附时间80 min的最佳工艺条件下,平均脱油率为98.67%,与模型计算值(100%)仅相差1.33%,剩余固体的平均含油率为0.37%。回收油的组分与0号柴油基本一致,可用于配制钻井液。剩余固体中未发现重金属元素和放射性元素,能够满足《页岩气勘探开发油基岩屑处理方法及控制指标》(GB/T 41518—2022)中“可用于油气田建设基础材料”的要求。

真空辅助微创旋切术与传统开放手术治疗乳腺良性肿瘤的效果比较

目的:比较真空辅助微创旋切术与传统开放手术治疗乳腺良性肿瘤的效果。方法:选取2021年6月—2022年5月滨州市中心医院收治的200例乳腺良性肿瘤患者作为研究对象,采用随机数字表法分为研究组和对照组,各100例。对照组接受传统开放手术治疗,研究组接受真空辅助微创旋切术治疗。比较两组治疗效果。结果:研究组手术时间、住院时间、切口长度短于对照组,术中出血量少于对照组,差异有统计学意义(P<0.05)。治疗前,两组躯体功能、心理功能、社会功能、物质生活评分比较,差异无统计学意义(P>0.05);治疗后,两组躯体功能、心理功能、社会功能、物质生活评分高于治疗前,且研究组高于对照组,差异有统计学意义(P<0.05)。研究组治疗满意度高于对照组,差异有统计学意义(P=0.011)。研究组并发症发生率低于对照组,差异有统计学意义(P=0.014)。结论:与传统开放手术相比,真空辅助微创旋切术治疗乳腺良性肿瘤的效果更优,可减少术中出血量,缩短切口长度,促进术后康复,改善患者生活质量,提高患者满意度,降低并发症发生率。

光子晶体结构生色真丝织物的制备及应用研究

为实现真丝织物的结构生色,文章分别利用真空辅助过滤法和手绘法在白色真丝织物上构筑光子晶体结构。进一步探究真空辅助过滤法中微球组装液体积浓度对结构色的影响规律,分析微球在真丝织物上形成光子晶体运动机制,讨论真丝织物上光子晶体结构色的虹彩效应,并探究手绘法在真丝织物光子晶体结构生色中的应用效果。结果表明:真空辅助过滤法中聚(苯乙烯-甲基丙烯酸),即P(St-MAA)微球组装液的体积浓度为2.4 L/m^(2)时,真丝织物的两面能同时获得光子晶体结构色,此时正反面结构色的反射率峰值在18%左右;在真空辅助过滤法中,P(St-MAA)微球在真丝织物上形成光子晶体结构的过程遵循“先反后正”堆积原则,即织物反面先形成光子晶体,随后微球进一步透过织物堆积在正面。此外,该光子晶体结构生色真丝织物的虹彩效应不明显,与常规染料或颜料着色效果接近;手绘法可以获得图案化的光子晶体生色结构,较适合于个性化加工。该研究为光子晶体结构生色在真丝织物着色中的应用提供参考。

电泳烘烤对EP/CF及EP/CF/GF复合材料力学性能的影响

采用真空辅助树脂传递模塑(VARTM)工艺制备了不同铺层方式的碳纤维增强聚合物基复合材料(CFRP):环氧树脂/碳纤维(EP/CF)和环氧树脂/碳纤维/玻璃纤维毡(EP/CF/GF)复合材料,重点研究了不同铺层纤维体系的CFRP渗透率以及电泳烘烤前后的力学性能变化,探究了其失效机理。结果表明,[±45°]铺层方式有利于体系中树脂的浸润,且加入GF能够明显提高体系的渗透率;电泳烘烤后,CF[0/90°]、CF[±45°]和CF/GF[±45°]的拉伸强度分别下降了15.65%、12.05%和6.77%,模量分别下降了9.08%、16.39%和10.04%,而CF/GF[0/90°]的拉伸强度和模量则分别提高了7.74%和6.95%;在弯曲性能方面,电泳烘烤后CF[0/90°]、CF/GF[0/90°]、CF[±45°]和CF/GF[±45°]的弯曲强度分别下降了7.62%、8.23%、15.89%和48.39%,模量分别降低了9.23%、3.69%、17.85%和34.38%;而电泳烘烤对4种材料的压缩性能影响较小;电泳后,CF[0/90°]和CF[±45°]的储能模量、损耗模量均有一定幅度提高,CF/GF[0/90°]和CF/GF[±45°]的储能模量、损耗模量均有下降。

基于VARTM的碳纤维单向与三维编织混杂织物树脂灌注工艺

为探究碳纤维单向与三维编织混杂增强环氧树脂基复合材料地铁转向架侧梁的树脂灌注成型工艺,首先基于渗透率理论模型采用非饱和径向流法分别测试得到碳纤维单向与三维编织织物的渗透率。通过数值模拟的方法对典型复合材料方形管结构进行缩比建模与网格划分,并利用PAM-RTM软件对树脂灌注成型过程进行仿真分析,预测了制备复合材料方管所需的灌注时间、灌注压力以及树脂流动过程缺陷的产生。最后根据模拟的灌注方案通过真空辅助树脂传递模塑(VARTM)成型工艺制备了碳纤维单向和三维编织混杂织物增强环氧树脂复合材料方管结构件。结果表明,通过PAM-RTM模拟VARTM工艺制备复合材料方管时树脂的流动,预测得到灌注时间为3897 s,VARTM工艺实际制备复合材料方管的灌注时间为4052 s,误差约为3.8%,在合理误差范围内。方管内部灌注压力随着与注胶口距离的增加而逐渐减小。模拟与实验的误差可能是由于实际铺层和灌注过程中树脂流动引起织物的剪切变形以及真空度的差异导致渗透性能产生变化。仿真模拟和实际制备复合材料方管均无明显缺陷产生,证明径向法织物渗透率的理论模型计算测试和仿真结果具有可靠性。

Characterization of the Grain Structures in Vacuum-Assist HighPressure Die Casting AM60B Alloy

The structures in vacuum-assist high-pressure die casting （HPDC） AM60B alloy were studied by using an optical microscope and a scanning electron microscope with an energy dispersive spectrometer. It was found that the HPDC under the vacuum could significantly change the morphology and distribution of the microstructure. For both conventional and vacuum-assist HPDC processes, the externally solidified crystals （ESCs） tended to aggregate in the center along the thickness direction of the castings. Besides, the aggregation was more pronounced, and the number of ESCs decreased, and the ESCs tended to become smaller and more globular, as the distance between the specimen location and runner increased. Compared with the conventional castings, the vacuum-assist HPDC can significantly reduce the size and amount of ESCs, and the ESCs tended to be more globular. For the distribution of ESCs along the thickness of the specimens, the aggregation tendency was more pronounced in vacuum-assist die castings than that in conventional castings. Besides, the distribution of ESCs at different locations was more converged in the vacuum-assist HPDC than that in the conventional HPDC.

负压辅助愈合治疗系统对糖尿病足溃疡患者创面愈合及疼痛程度的影响

目的 探讨负压辅助愈合治疗系统对糖尿病足溃疡患者创面愈合及疼痛程度的影响。方法 选取2022年2月—2024年2月南通市第三人民医院收治的80例糖尿病足溃疡患者为研究对象,按照治疗方法的不同分为对照组和观察组,每组40例。对照组接受常规创面处理,观察组在对照组基础上使用负压辅助愈合治疗系统。比较两组创面愈合效果、血液炎症指标、视觉模拟法(Visual Analogue Scale, VAS)评分。结果 治疗后,观察组创面深度和溃疡面积均小于对照组,差异有统计学意义(P均<0.05)。治疗后,观察组白细胞计数、中性粒细胞比率、C反应蛋白、降钙素原水平均低于对照组,差异有统计学意义(P均<0.05)。治疗后,观察组VAS评分低于对照组,差异有统计学意义(P<0.05)。结论 负压辅助愈合治疗系统能促进糖尿病足溃疡患者的创面愈合,改善血液炎症指标,并有效降低疼痛程度,为糖尿病足溃疡的综合治疗提供了重要的临床依据。