热喷涂铝青铜涂层的制备与微动磨损行为*

采用大气等离子喷涂和超音速火焰喷涂在不锈钢表面制备铝青铜涂层,并考察涂层的显微组织、相组成以及微动磨损行为。结果表明,在微动初期涂层接触区内发生轻微损伤,表现为犁沟和粘着;随微动循环次数的增加,层状剥离和氧化成为涂层接触区内的主要损伤形式。超音速火焰喷涂涂层具有更高的致密度和硬度,提高了涂层抗粘着及犁削的性能,故在试验初期表现出较小的摩擦因数和磨损体积;但在微动损伤机制随循环次数增大转变为层状剥离和氧化后,大气等离子喷涂涂层具有更小的摩擦因数和磨损体积。这可能是由于大气等离子喷涂涂层具有更高含量的α相,提高了涂层的韧性抑制了脆性断裂。此外,磨痕内形成的致密氧化层和由应变强化得到的致密化组织减缓了涂层的进一步磨损和氧化。     

3D modeling of residual stresses induced in finish turning of an AISI304L stainless steel

This paper addresses the development of a new methodology predicting residual stresses induced in finish turning of a AISI304L stainless steel. A hybrid approach combining experimental results and a numerical model is applied. The model simulates the residual stresses generation by applying equivalent thermo-mechanical loadings onto the machined surface without modeling the chip removal process, which enables rapid calculation. The shape and the intensity of equivalent thermo-mechanical loadings are identified through experimental measurements. Friction tests enable to model the thermal and mechanical loadings along the tool-workmaterial interface. Orthogonal cutting tests provide thermal and mechanical loadings below the primary and third shear zone. This model has already been presented in several papers, but only in a 2D configuration. The objective of this paper is to transfer this hybrid approach into a 3D configuration, which is closer to a concrete longitudinal turning operation. Based on this new model, the paper aims at investigating the interactions between each revolution. It is shown that around five revolutions are necessary to reach a steady state. Finally numerical results are compared with experimental measurements obtained by X-Ray diffraction. It is shown that residual stresses cannot be considered as homogeneous over the surface due to tool's feed. Additionally, the X-Ray beam is much too large to be able to quantify this heterogeneity. Based on average numerical values coherent with average values obtained by X-Ray diffraction, it is shown that the numerical model provides consistent results compared to experimental measurements for a large range of cutting speed and feed.     

石南31井区清水河组层序地层划分及特征

石南31井区位于准噶尔盆地腹部,井区下白垩统清水河组油藏为一新发现的高产油藏,尚未进行过层序地层学研究。根据三维地震信息、测井响应特征、岩心及岩屑录井资料,首次在清水河组识别出3个层序界面:一是清一段底面,即白垩系与侏罗系的分界面(SB1);二是清一段中KIq11-1与K1q11-2的界面(SB2);三是清二段顶面(SB3)。并根据这三个层序界面,划分出两个三级层序,自下而上为"层序I"和"层序II"。层序I包括清一段的第二砂层组和第一砂层组的K1q11-2,K1q11-3砂层;层序II则包括清一段第一砂层组的KIq11-1砂层和整个清二段。     

Low-temperature synthesis of mullite-based ceramics from Moroccan naturally occurring andalusite and marble waste

The present work aims to prepare mullite-based ceramics at low temperature mainly from andalusite and marble byproduct by a solid-state interaction method. Marble powder byproduct was used, in the prospect of waste management, as a sintering aid. The influence of marble powder byproduct (5 wt.%) on the phase formation, microstructure-temperature evolution, densification, and mechanical strength was evaluated by means of XRD, TGA-DTA, and SEM. The results revealed that the andalusite remained present with mullite up to 1400°C, while the addition of 5 wt.% of marble byproduct involved its complete transformation into mullite and a trace of anorthite. The transformation of andalusite into mullite upon the heating in the range 1300–1400°C involved the densification of the matrix body and a significant increase in mechanical strength from 60 to 170 MPa, which promoted its application for refractory materials.     

A continuous flow reactor for the flexible production of different formulations: CFD-aided design

The increasing need to improve the sustainability of industrial processes requires more flexible and intensified solutions. For this purpose, nowadays lots of efforts are made to switch from batch to continuous processes, the latter being able to ensure the same processing history to all fluid elements, with a consequent better control of the operating conditions and product quality. The present work aims at developing a continuous flow reactor for the production of several fine chemicals, including medical-surgical aids, but also other substances for specific industrial sectors. The plant is basically an inline reactor equipped with various static mixers and side inlets, and it is conceived to ensure on-site production. This is an important feature also in light of the recent COVID-19 pandemic, which asked for flexible and distributed production of chemicals. Numerical simulations based on computational fluid dynamics are employed to study the performance, in terms of pressure drops and degree of mixing, of different static mixers, that is, the Lightnin Inliner Series 50 and Ross low pressure drop (LPD), combining various elements of mixing and injections in different operating conditions in both laminar and turbulent regimes. The results highlighted how numerical simulations may represent a valid tool for supporting the detailed design of such flow reactors by allowing the evaluation of the optimal design solutions.     

基体表面形貌对膜基结合强度影响规律的研究

借助分子动力学方法对薄膜成核的微观过程和基体形貌进行了模拟分析.当基体形貌的偏斜度Sk为负值时,接触角θ较小,成核率较高;随着Sk的降低,基体的形貌满型增多,沉积粒子参与成团的个数也随之增加,从而成核率也会增加,进而利于薄膜随后的长大、成膜.从理论上证明了不同的基体表面形貌对基体与所形成的薄膜之间的结合强度有很大影响,偏斜度Sk取值在-1～-3时,所生长的薄膜膜基间结合强度高.     

Clinical and genetic characteristics of type 2 diabetes with and without GAD antibodies

The aim of the study was 1) to establish the prevalence of GAD antibodies (GADab) in a population-based study of type 2 diabetes in western Finland, 2) to genetically and phenotypically characterize this subgroup, and 3) to provide a definition for latent autoimmune diabetes in adults (LADA). The prevalence of GADab was 9.3% among 1,122 type 2 diabetic patients, 3.6% among 558 impaired glucose tolerance (IGT) subjects, and 4.4% among 383 nondiabetic control subjects. Islet antigen 2 antibodies (IA2ab) or islet cell antibodies were detected in only 0.5% of the GADab- patients. The GADab+ patients had lower fasting C-peptide concentrations (median [interquartile range]: 0.46 [0.45] vs. 0.62 [0.44] nmol/l, P = 0.0002) and lower insulin response to oral glucose compared with GADab- patients. With respect to features of the metabolic syndrome, the GADab+ patients had lower systolic (140 [29.1] vs. 148 [26.0] mmHg, P = 0.009) and diastolic (79.2 [17.6] vs. 81.0 [13.1] mmHg, P = 0.030) blood pressure values, as well as lower triglyceride concentrations (1.40 [1.18] vs. 1.75 [1.25] mmol/l, P = 0.003). GADab+ men had a lower waist-to-hip ratio compared with GADab- patients. Compared with GADab- patients and control subjects, the GADab+ patients had an increased frequency HLA-DQB1*0201/0302 (13 vs. 4%; P = 0.002) and other genotypes containing the *0302 allele (22 vs. 12%; P = 0.010). However, the frequency of these high-risk genotypes was significantly lower in GADab+ type 2 patients than in type 1 diabetes of young or adult onset (0201/0302 or 0302/X: 36 vs. 66 vs. 64%, P < 0.001). The GADab+ type 2 group did not differ from control subjects with respect to genotypes containing the protective DQB1-alleles *0602 or *0603, nor with respect to the type 1 high-risk genotype in the IDDM1 (Hph1 +/+). We conclude that GADab+ patients differ from both GADab- type 2 diabetic patients and type 1 diabetic patients with respect to beta-cell function, features of the metabolic syndrome, and type 1 diabetes susceptibility genes. Further, we propose that LADA be defined as GADab positivity (>5 relative units) in patients older than 35 years at onset of type 2 diabetes.     

Evaluation of patients with bladder outlet obstruction and mild international prostate symptom score followed up by watchful waiting

OBJECTIVES: To examine the variability of bladder outlet obstruction and mild lower urinary tract symptoms in patients with benign prostatic hyperplasia (BPH) followed up by watchful waiting. METHODS: The International Prostate Symptom Score (IPSS) has four questions related to voiding symptoms and three related to filling symptoms. Scores of 0 to 7, 8 to 19, and 20 to 35 represent mild, moderate, and severe symptoms, respectively. Over a period of 36 months the IPSS questionnaire was administered to 479 patients 50 to 81 years old (mean age 63) with BPH. A pressure-flow study was used to determine the presence of bladder outlet obstruction. On the basis of their scores, the patients were classified into 50 with mild, 227 with moderate, and 202 with severe symptoms. In the present study only patients with a mild score were analyzed. RESULTS: Of 50 patients with mild symptoms, 16 (32%) had bladder outlet obstruction. After a period of 9 to 22 months (mean 17) of watchful waiting, these 16 patients were reviewed. Twelve (75%) of the 16 had bladder outlet obstruction reconfirmed by pressure-flow studies, and 3 (18.8%) of 16 had increased symptoms (moderate symptomatic) and underwent treatment (1 began pharmacologic treatment, and 2 chose transurethral resection). A total of 4 (25%) of 16 patients still had mild voiding disturbances and refused the second urodynamic evaluation. The remaining 34 patients with no obstruction had annual routine follow-up and had persistent mild symptom scores and normal uroflowmetric results. These patients did not undergo another pressure-flow evaluation. CONCLUSIONS: A pressure-flow study is routinely avoided in patients with a mild IPSS. From symptoms alone it was not possible to diagnose bladder outlet obstruction in these patients. Pressure-flow studies and symptom profiles measure different aspects of the clinical condition. After a mean follow-up of 17 months of watchful waiting, 13 (81.2%) of 1 6 patients were clinically stable. Because the need for therapy is dictated by quality of life, it is difficult to propose treatment for patients with minimal symptoms, even in the presence of bladder outlet obstruction.