基于BP-ANN和Sellars模型的镍基高温合金晶粒长大行为表征及其比较

为了深入理解Ni80A的晶粒长大行为,在不同温度(1223~1423 K)和不同保温时间(0~3600 s)下进行一系列的晶粒长大实验。基于实验数据,建立BP神经网络并求解Sellars模型。使用4个统计指标比较和评价这两个模型的预测与泛化能力。结果表明,所建立的BP神经网络具有更高的r值、更低的AARE值、更低的绝对μ值和ω值。最后,基于求解的BP神经网络扩展的数据建立平均晶粒尺寸对保温温度和保温时间的响应面,并描述晶粒的长大行为。

Predictive visual field outcomes after optic chiasm decompressive surgery by retinal vessels parameters using optical coherence tomography angiography

AIM:To evaluate the predictive value of superficial retinal capillary plexus(SRCP)and radial peripapillary capillary(RPC)for visual field recovery after optic cross decompression and compare them with peripapillary nerve fiber layer(pRNFL)and ganglion cell complex(GCC).METHODS:This prospective longitudinal observational study included patients with chiasmal compression due to sellar region mass scheduled for decompressive surgery.Generalized estimating equations were used to compare retinal vessel density and retinal layer thickness preand post-operatively and with healthy controls.Logistic regression models were used to assess the relationship between preoperative GCC,pRNFL,SRCP,and RPC parameters and visual field recovery after surgery.RESULTS:The study included 43 eyes of 24 patients and 48 eyes of 24 healthy controls.Preoperative RPC and SRCP vessel density and pRNFL and GCC thickness were lower than healthy controls and higher than postoperative values.The best predictive GCC and pRNFL models were based on the superior GCC[area under the curve(AUC)=0.866]and the tempo-inferior pRNFL(AUC=0.824),and the best predictive SRCP and RPC models were based on the nasal SRCP(AUC=0.718)and tempo-inferior RPC(AUC=0.825).There was no statistical difference in the predictive value of the superior GCC,tempo-inferior pRNFL,and tempo-inferior RPC(all P>0.05).CONCLUSION:Compression of the optic chiasm by tumors in the saddle area can reduce retinal thickness and blood perfusion.This reduction persists despite the recovery of the visual field after decompression surgery.GCC,pRNFL,and RPC can be used as sensitive predictors of visual field recovery after decompression surgery.

Pituitary metastasis from lung adenocarcinoma:A case report

BACKGROUND Pituitary gland metastasis is an unusual event,and pituitary metastasis from lung adenocarcinoma is extremely rare and associated with poor prognosis.To date,approximately 15 cases have been reported.CASE SUMMARY Here,we present the case of a 64-year-old woman with pituitary metastasis derived from lung adenocarcinoma,which was difficult to distinguish from other sellar tumors.The patient presented to the neurosurgery clinic with blurred vision and intermittent headache.During hospitalization,brain computed tomography(CT)and magnetic resonance imaging revealed a pituitary macroadenoma.Chest CT revealed irregular nodules in the basal segment of the lower lobe of the left lung,which were likely lung cancer.Positron emission tomography-CT revealed a carbohydrate metabolism tumor in the lungs and sellar region,which was considered malignant.Postoperative pathological examination of the sellar tumor revealed lung adenocarcinoma.CONCLUSION Excision of pituitary metastases combined with radiotherapy and chemotherapy should be a priority treatment for patients with pituitary metastasis.

0.22C-0.45Mn钢低温奥氏体晶粒长大行为的研究

对0.22C-0.45Mn钢进行淬火工艺实验,研究加热温度、保温时间对奥氏体晶粒平均直径的影响,探究0.22C-0.45Mn钢在加热温度(870~990℃)和保温时间(15~120 min)范围内的低温奥氏体晶粒长大行为;基于Beck,Hillert和Sellars模型分别建立奥氏体晶粒平均直径的数学模型,预测0.22C-0.45Mn钢的奥氏体晶粒直径。结果表明:随加热温度的升高,0.22C-0.45Mn钢奥氏体晶粒直径近似呈指数形式增长,长大速率加快;随保温时间的延长,奥氏体晶粒增长速率减缓;3种晶粒模型中,Sellars模型的拟合精度最高,能较好地预测0.22C-0.45Mn钢奥氏体晶粒直径,可为实际生产中旋扩后的0.22C-0.45Mn钢低温热处理工艺提供参考依据。

40CrNi2MoE钢奥氏体晶粒长大的数学模型

利用金相实验方法,基于实验数据,应用Beck、Hillert、Sellars数学模型研究了40CrNi2MoE钢在加热温度850~1200℃和保温时间30~480 min下的奥氏体晶粒长大规律。结果表明,随加热温度升高和保温时间延长,40CrNi2MoE钢奥氏体晶粒逐渐长大,当加热温度超过1050℃或保温时间超过120 min时,试验钢奥氏体晶粒开始粗化。通过对Beck、Hillert和Sellars 3种晶粒长大数学模型对比分析,Sellars模型对40CrNi2MoE钢的奥氏体晶粒尺寸预测具有较高的精度,其奥氏体晶粒长大模型方程为:当温度为850℃≤T≤1050℃时,D5.49Sellars=7.64×1021texp(-390081/(RT));当温度为1050℃≤T≤1200℃时,D8.13Sellars=8.04×1041texp(-771322/(RT))。

20CrMnTiH钢奥氏体晶粒长大规律及有限元模拟

通过金相实验,对20Cr Mn Ti H钢在不同加热温度（850-1150℃）及保温时间（10-40 min）下的晶粒长大规律进行了研究,基于所得数据,通过回归分析建立了适用于此种材料加热与保温过程的奥氏体晶粒长大模型,并将该模型引入有限元软件对奥氏体晶粒长大行为进行数值模拟。结果表明,奥氏体晶粒尺寸随加热温度升高而增大,且长大速度越来越快,随保温时间延长而增大,且长大速度不断减缓;1000℃为20Cr Mn Ti H钢的粗化温度,T≤1000℃时,晶粒长大缓慢,T≥1000℃时,晶粒急剧长大;有限元软件成功模拟了奥氏体晶粒长大过程,模拟结果与实验结果相符。

高强渗碳钢高温热变形的本构方程

采用Gleeble-3800热模拟试验机,在温度为1173~1473 K,应变速率为0.01~10 s-1的变形条件下,对一种航空用高强度渗碳钢-9310钢进行热压缩实验,基于真应力-应变曲线,研究了两种高温变形流变应力的本构方程模型-位错模型和Sellars模型在该钢上的应用,根据动态再结晶是否发生,建立了不同热变形阶段下9310钢的流变应力本构方程。研究表明,在ε】0.1条件下的动态软化和稳态流变阶段中,基于位错密度和动态软化机制的位错模型方程,精度误差在15%以下,但该方程参数多,计算量大,而基于Sellars模型的本构方程,在低温热变形(T【1273 K)及大应变(ε】0.5)条件下的精度误差更小,且方程相对简单,便于应用。在高强渗碳9310钢的热加工生产中,建议采用Sellars模型作为大应变条件下流变应力的预报方程,精度误差控制在10%以下;为了提高方程精度,Sellars模型下由于动态再结晶软化引起的应力降低值Δσ中,相关参数的取值还有进一步修正的可能。

中碳34CrNiMo合金钢加热过程中奥氏体晶粒长大行为（英文）

对中碳34CrNiMo合金钢在加热温度900~1200℃和保温时间0~360 s下的奥氏体晶粒演化行为进行了研究。结果表明,随着加热温度的升高和保温时间的延长,奥氏体晶粒尺寸呈现逐渐增大的趋势。基于晶粒长大的Sellars模型,通过线性回归方法建立34CrNiMo钢加热时奥氏体晶粒长大的数学模型。将晶粒长大模型预测结果与实验结果进行比较,符合良好,表明该模型能够较好地预测34CrNiMo钢奥氏体晶粒长大行为。

Sellar Chordoma Presenting as Pseudo-macroprolactinoma with Unilateral Third Cranial Nerve Palsy

We described a 61-year-old female with a sellar chordoma, which presented as pseudo-macroprolactinoma with unilateral third cranial nerve palsy. Physical examination revealed that her right upper lid could not be raised by itself, right eyeball movement limited to the abduction direction, right pupil dilated to 4.5 mm with negative reaction to light, and hemianopsia in bitemporal sides. CT scanning showed a hyperdense lesion at sellar region without bone destruction. Magnetic resonance imaging （MRI） revealed the tumor was 2.3 cmx2.8 cmx2.6 cm, with iso-intensity on TlWl, hyper-intensity on T2WI and heterogeneous enhancement on contrast imaging. Endocrine examination showed her serum prolactin level increased to 2,032.49 mlU/ml. The tumor was sub-totally resected via pterional craniotomy under microscope and was histologically proven to be a chordoma. Postoperatively, she recovered uneventfully but ptosis and hemianopsia remained at the 6th month.

Evaluation of Empty Nose Syndrome Scores in Patients Undergoing Extended Endoscopic Transnasal Sellar Surgery

Background: Several large series have established endoscopic transnasal sellar surgery as the procedure of choice for removal of tumors in the sellar area. Although this procedure provides a less invasive approach to the sella, it entails complications such as nasal bleeding, impaired olfactory function, atrophic rhinitis, synechiae, etc. No studies have yet reported potential morbidities such as empty nose syndrome (ENS), although patients have a relatively empty nasal cavity after surgery. Therefore, we sought to verify the percentage of patients who truly met the diagnostic criteria for ENS after endoscopic transnasal sellar surgery, determine the variation between pre- and postoperative scores in each Empty Nose Syndrome 6-Item Questionnaire (ENS6Q) item, and further evaluate the symptoms that may affect the patients the most after surgery. Methods: Between March 2015 and January 2019, eventually 11 patients who underwent extended endoscopic transnasal sellar surgery in Shin Kong Wu Ho-Su Memorial Hospital, a tertiary referral medical center in Taipei, Taiwan, were enrolled. The patients completed the recently validated ENS6Q after surgery. Results: One patient met the objective diagnostic criteria for ENS (score ≥ 11 in ENS6Q). Significant differences were observed in the pre- and postoperative total ENS6Q scores. The pre- and postoperative scores of “nose feeling too open” and nasal crusting showed statistically significant differences. Further, compared with the other items, the postoperative score of nasal crusting increased most obviously, and it may be the most apparent operation-related symptom. Conclusion: This study is the first to report the possibility of developing ENS after endoscopic transnasal sellar surgery. Although the transnasal endoscopic approach is a safe and minimally invasive procedure for the treatment of sellar lesions, possible complications such as ENS should be considered.

Sellar Arachnoidocele: An Unusual Evolution in a Case Report

The sellar archnoidocele is a herniation of the subarachnoid space within the sella turcica which is often associated with a variable degree of flattening of the pituitary. Its clinical presentations range from an asymptomatic radiological finding to endocrine and neuro-ophthalmological manifestations. Its management depends on the initial symptomatology and requires long-term follow-up. We report here the case of a young child followed for a statural delay on a GH deficiency secondary to a sellar arachnoidocele, and who presents a rather unusual evolution.

Individualized Sellar Floor Reconstruction Method and Nursing Strategy for the Intraoperative Cerebrospinal Fluid Leakage Caused by Neuroendoscopic Transsphenoidal Pituitary Adenoma Resection

Objective: To explore the clinical effect of and the method and nursing strategy for sellar reconstruction for intraoperative cerebrospinal fluid (CSF) leakage in pituitary adenoma resection under neuroendoscopy. Methods: The data from 20 cases of intraoperative CSF leak caused by transsphenoidal pituitary adenoma resection were retrospectively analyzed. Six patients were treated with mucosal flap and artificial dural reconstruction of sellar (simple sellar floor reconstruction). In 45 patients, autologous fat, fascia lata, and artificial dura were used to repair and reconstruct the sellar floor (multilayer sellar floor reconstruction). After the operation, all patients underwent follow-up for 6 - 24 months. Results: Fifty patients were followed up without CSF leakage. One patient was cured after leakage of CSF through the lumbar cistern 1 month after discharge. Conclusion: For patients with CSF leakage during neuroendoscopic transsphenoidal pituitary adenoma resection, individualized sellar floor reconstruction should be adopted according to the degree of CSF leakage and the size of the sellar floor defect. Strict nursing measures can effectively prevent CSF leakage and reduce postoperative complications.

Intra-Sellary Arachniodocele: About a Case at the Medical Clinic “The Stars” of Bamako

Intrasellar arachnoidocele is a herniation of the optochiasmatic cistern through a dehiscence of the sellar diaphragm producing an empty sella turcica, hence its name empty sella turcica syndrome. It is an extremely rare benign malformative pathology. We report a case of intra-sellar arachnoidocele in a 34-year-old woman revealed during an annual control of a sellar mass under dossinex by cerebral magnetic resonance imaging (MRI) which found the cystic formation of liquid signal identical to that of the LCS in hypo signal T1 and hyper signal T2 without enhancement after injection of Gadolinium. The epidemiological, clinical and radiological aspects of arachnoidocele were analyzed. The purpose of this work is to bring the interest of MRI in the management of this pathology.

退火工艺对29Cr-4Mo超级铁素体不锈钢微观组织的影响

以冷轧态29Cr-4Mo超级铁素体不锈钢无缝钢管为研究对象,研究了不同退火工艺对29Cr-4Mo超级铁素体不锈钢无缝钢管冷轧后微观组织的影响。结果表明,29Cr-4Mo超级铁素体不锈钢夹杂物主要成分为Cr_(2)O_(3)·MnO·Al_(2)O_(3);在900℃下保温30 min,晶界三角连接处和夹杂物附近率先生成了少量σ相,σ相析出的平均面积分数随时间的延长而增加,随温度的升高而减少;当温度升高至1000℃,保温50 min未见有σ相析出,在900~1050℃整个温度区间内未见有χ相析出;建立了Sellars模型下铁素体再结晶晶粒长大经验公式,通过对比分析计算值与实验值,结果显示该公式能准确预测整个退火过程中的平均晶粒尺寸。

20CrMnTi钢和20钢奥氏体晶粒长大行为对比

通过试验研究了20CrMnTi钢和20钢在不同保温温度(1000~1200℃)和不同保温时间(0~300 s)条件下的奥氏体晶粒长大行为,并基于试验结果建立了描述奥氏体晶粒长大行为的Sellars数学模型。通过对比两种钢的奥氏体晶粒长大模型计算值与试验值的平均相对误差(AARE)和相关系数(R),验证了模型的可靠性。试验与模拟结果表明,随着加热温度的升高,试验钢晶粒尺寸都有明显的增加;随着保温时间的延长,在前60 s晶粒尺寸增长快速,之后增速减缓。但在相同试验条件下,20CrMnTi钢的奥氏体晶粒尺寸都明显小于20钢,且没有出现晶粒异常长大现象,说明Ti元素的添加具有明显细化组织的作用。

Cr-Mo-V高铁制动盘用钢的奥氏体晶粒长大行为

研究了在不同加热温度和保温时间下Cr-Mo-V系制动盘用钢的奥氏体晶粒长大行为,并采用光学显微镜以及截距法分析了加热温度和保温时间对钢的奥氏体晶粒尺寸和分布的影响。依据Thermo-Calc热力学计算软件计算了试验钢在400~1600℃范围内的析出相以及析出相的元素组成。结果表明:随着加热温度的升高,奥氏体晶粒尺寸不断增加,在850~900℃范围内,钢的奥氏体晶粒尺寸增长缓慢,晶粒较细小,950℃时奥氏体晶粒出现了异常长大现象,随后奥氏体晶粒快速长大。随着保温时间的延长,奥氏体晶粒尺寸也不断增加,但保温时间对奥氏体晶粒尺寸的影响比奥氏体化温度对奥氏体晶粒的影响小。结合扫描电镜分析,确定了本试验钢晶界处的析出相为V(C,N)。根据Sellars模型,确定了Cr-Mo-V试验钢的晶粒长大模型。

A315钢奥氏体晶粒长大的数学模型

采用金相试验,应用Beck、Hillert、Sellars数学模型分析了A315钢再结晶过程中不同加热温度和保温时间下的奥氏体晶粒长大行为。结果表明,随加热温度的升高和保温时间的延长,A315钢奥氏体晶粒逐渐长大,其长大过程可以分为抑制长大阶段和自由长大阶段。通过对比Beck、Hillert、Sellars三种奥氏体晶粒长大数学模型,得出Sellars模型对A315钢奥氏体晶粒尺寸的预测有很高的精度,其数学模型方程为:当温度为950℃≤T≤1100℃时,D2.42=2.65×107texp(-187 284/(RT));当温度为1150℃≤T≤1200℃时,D2.86=3.04×1024texp(-589 475/(RT))。

低碳Nb-V-Ti微合金钢X70的奥氏体晶粒长大行为

利用金相试验法对低碳Nb-V-Ti管线钢X70在1000～1200℃和0～600 s之间的奥氏体晶粒演化行为进行研究,并利用Beck、Hillert、Sellars数学方程建立了该钢种的晶粒长大模型。结果表明,试验过程中,保温温度越高,时间越长,晶粒尺寸越大,在1150℃以上晶粒越粗化。通过对3种晶粒长大方程:Beck模型,Hillert模型以及Sellars模型的对比分析,Sellars模型对X70管线钢晶粒长大预测精度最高。将模型的预测值与试验结果进行比较,符合较好,说明该方程能够较好预测X70钢的晶粒长大行为。

加热温度及保温时间对M50NiL钢奥氏体晶粒尺寸的影响

利用光学显微镜、场发射扫描电镜、MIAPS图像分析软件研究了加热温度(1050~1150℃)及保温时间(10~70min)对M50NiL钢奥氏体晶粒尺寸的影响。结果表明:随加热温度的升高,M50NiL钢奥氏体晶粒尺寸呈指数型增长,而保温时间与奥氏体晶粒尺寸近似呈线性关系,奥氏体晶粒尺寸增长缓慢;当加热温度从1050℃升高到1150℃时,M50NiL钢中第二相粒子不稳定,出现溶解现象,钉扎作用削弱,使晶粒尺寸变化显著。基于Sellars模型,对试验数据进行回归分析、计算,得出M50NiL钢奥氏体晶粒长大动力学方程,经验证与实测值吻合较好。

H13钢锻材加热时的奥氏体晶粒长大规律

利用金相试验方法,对H13钢锻材在不同加热温度(1030~1150℃)及保温时间(30~120 min)下的奥氏体晶粒长大规律进行研究。结果表明:温度升高和保温时间延长均可促使H13钢奥氏体晶粒的不断长大,温度升高对晶粒长大的促进作用更显著。H13钢的奥氏体晶粒粗化温度在1100~1120℃之间,优选固溶温度为1100℃。在Sellars模型的基础上,对试验数据进行回归分析,建立了H13钢锻材加热时奥氏体晶粒长大模型:D^5.369=D0^5.369+5.6154×1097exp[-2431 085.76/RT]t,该模型计算值与测量值吻合度较高。