Optimization of Process Parameters and Analysis of Microstructure and Properties of 18Ni300 by Selective Laser Melting

In this research, we studied the influence of process parameters on the quality of selective laser melting of 18Ni300 maraging steel. The effects of laser power and scanning speed on the relative density and hardness of 18Ni300 were studied by single-factor experiment and the orthogonal experimental method. The relative optimal process parameters of 18Ni300 were obtained when the layer thickness was 0.03 mm, and the hatch space was 0.1 mm. The microstructures and mechanical properties of the samples formed under different process parameters were characterized. The results showed that the optimal hardness and relative density of the sample were 44.7 HRC and 99.98% when the laser power was 230 W and the scanning speed was 1100 mm/s, respectively; the microstructure of the material was uniform and dense, exhibiting few pores. Some columnar crystals appeared along the boundary of the molten pool due to vertical epitaxial growth. The orientation of fine grains at the boundary of the molten pool was random, and some coarse columnar crystals in the molten pool exhibited a certain orientational preference along the <001> orientation. In the case of optimal process parameters, the SLM-formed 18Ni300 was composed of 99.5% martensite and 0.5% retained austenite; the indentation hardness was distributed in the range of 3.2–5 GPa. The indentation modulus was between 142.8–223.4 GPa, exhibiting stronger fluctuations than the indentation hardness. The sample’s mechanical properties showed obvious anisotropy, while the tensile fracture characteristics exhibited necking. The tensile fracture morphology was ductile, and large equiaxed dimples and holes could be observed in the fiber area, accompanied by tearing characteristics.     

Gregor Johann Mendel and Modern Evolutionary Biology: Gregor Johann Mendel: From peasant to priest,pedagogue, and prelate

Gregor Mendel was an Augustinian priest in the Monastery of St. Thomas in Brünn (Brno, Czech Republic) as well as a civilian employee who taught natural history and physics in the Brünn Modern School. The monastery’s secular function was to provide teachers for the public schools across Moravia. It was a cultural, educational, and artistic center with an elite core of friar-teachers with a well-stocked library and other amenities including a gourmet kitchen. It was wealthy, with far-flung holdings yielding income from agricultural productions. Mendel had failed his tryout as a parish priest and did not complete his examination for teaching certification despite 2 y of study at the University of Vienna. In addition to his teaching and religious obligations, Mendel carried out daily meteorological and astronomical observations, cared for the monastery''s fruit orchard and beehives, and tended plants in the greenhouse and small outdoor gardens. In the years 1856 to 1863, he carried out experiments on heredity of traits in garden peas regarded as revolutionary today but not widely recognized during his lifetime and until 16 y after his death. In 1868 he was elected abbot of the monastery, a significantly elevated position in the ecclesiastical and civil hierarchy. While he had hoped to be elected, and was honored to accept, he severely underestimated its administrative responsibilities and gradually had to abandon his scientific interests. The last decade of his life was marred by an ugly dispute with civil authorities over monastery taxation.     

Appraising Adjuvant Endocrine Therapy in Hormone Receptor Positive HER2-Negative Breast Cancer—A Literature Review

Background: Approximately 75% of breast cancer (BC) is associated with luminal differentiation expressing endocrine receptors (ER). For ER+ HER2− tumors, adjuvant endocrine therapy (ET) is the cornerstone treatment. Although relapse events steadily continue, the ET benefits translate to dramatically lengthen life expectancy with bearable side-effects. This review of ER+ HER2− female BC outlines suitable adjuvant treatment strategies to help guide clinical decision making around appropriate therapy. Methods: A literature search was conducted in Embase, Medline, and the Cochrane Libraries, using ER+ HER−, ET BC keywords. Results: In low-risk patients: five years of ET is the standard option. While Tamoxifen remains the preferred selection for premenopausal women, AI is the choice for postmenopausal patients. In the high-risk category: ET plus/minus OFS with two years of Abemaciclib is recommended. Although extended ET for a total of ten years is an alternative, the optimal AI duration is undetermined; nevertheless an additional two to three years beyond the initial five years may be sufficient. In this postmenopausal group, bisphosphonate is endorsed. Conclusions: Classifying the risk category assists in deciding the treatment route and its optimal duration. Tailoring the breadth of ET hinges on a wide array of factors to be appraised for each individualized case, including weighing its benefits and harms.     

脑深部电刺激术的电极移位

目的研究脑深部电刺激术(DBS)电极移位的原因及预防措施.方法研究113例帕金森病DBS术中及术后程控时的深部电极与预置靶点的差异.结果发生电极移位5例,其中术中发生2例;3例术中刺激效果满意,电极未发生移位,但术后4周程控时达不到满意效果,复查头颅MRI示脑深部电极移位,2例比原定位置深4 mm,1例比原定位置深6 mm.结论植入的刺激电极在颅内移位是影响DBS治疗效果的重要因素,可造成某些病人术中刺激效果好,但一段时间后疗效差的现象,应积极预防.     

床旁球囊漂浮电极心脏临时起搏的疗效评价及观察

目的探讨球囊漂浮电极床旁心脏内临时起搏的可行性及其临床疗效。方法对36例病人经左锁骨下静脉途径,通过插入导管的长度和起搏心电图QRS波形态的指导,植入球囊漂浮导管至右心室行临时心脏起搏。结果成功起搏55例（97．22％）,开始穿刺到成功起搏时间（6．7±3．5）min,植入深度（37．5±3．5）cm,留置电极导管时间1—14d。无严重并发症发生。结论经锁骨下静脉途径植入球囊起搏电极导管能迅速安全行心室起搏。     

选择性激光熔覆微孔钛试件制备及体外生物学评价

目的 探究经碱酸热处理的选择性激光熔覆微孔钛在体外生物学活性方面是否具有优势.方法 制备光滑组(PT组)、喷砂酸蚀组(SLA组)、亲水组(ModSLA组)、选择性激光熔覆组(SLM组)、选择性激光熔覆-碱酸热处理组(SLM-T组)5种不同的钛表面,对各组试件表面人类血清白蛋白(HSA)吸附行为进行研究,在各组试件表面接种小鼠骨髓间充质干细胞(BMSCs)进行培养,评价不同钛试件表面的体外生物学活性.结果 在5、10、20、40、60 min时,SLM-T组对HSA具有相对良好的吸附特性.第1、3、5天,与其他3组相比,SLM组和SLM-T组表现出最为显著的增殖活性,差异有统计学意义(P＜0.01),第7天,5组试件碱性磷酸酶(AKP)的表达水平差异无统计学意义;第14天,SLM-T组有着最为显著的AKP表达水平,差异有统计学意义(P＜0.01),SLM组与PT组的AKP表达水平差异无统计学意义.结论 体外实验表明,经碱酸热处理的选择性激光熔覆微孔钛具有良好的体外生物学活性,可望促进骨结合,潜在地提升种植体植入后的初期稳定性.     

酶法、离子选择电极法检测血清钙方法的比较

目的用酶法、离子选择电极法(ISE)进行同步检测血清钙的含量,从中找出一种更为简便、灵敏、经济适用、快速准确的检测方法。方法随机抽取门诊病人标本30份,分别用酶法、离子选择电极法检测血清钙的含量,进行统计学处理和分析。结果30份标本中,酶法和离子选择电极法检测发现它们的回收率、线性范围、精密度均符合要求,重复性良好,结果无显著性差异。结论离子选择电极法较酶法速度快,适于抢救急诊重危病人使用;但对实验室条件及外电电源要求较高,电极需定期精心维护保养。酶法较为稳定,适合全自动化仪器和大批量标本检测的应用,但对黄疸较深和乳糜血、溶血等标本结果影响较大。     

Bronchodilation and safety of supratherapeutic doses of salbutamol or ipratropium bromide added to single dose GSK961081 in patients with moderate to severe COPD

BackgroundThere are few data on the bronchodilatory effects of adding short-acting bronchodilators (SABA) to maintenance, long-acting bronchodilator therapy. This study assessed the additional bronchodilation and safety of adding supratherapeutic doses of salbutamol (SALB) or ipratropium bromide (IPR) to the novel bi-functional molecule (or dual pharmacophore) GSK961081 400 μg (MABA 400) or 1200 μg (MABA 1200).MethodsThis randomised, double-blind, complete, crossover study in 44 patients with moderate to severe COPD, evaluated 6 treatments with a washout of at least 7 days between treatments: single doses of MABA 400 or MABA 1200 followed by cumulative doses of either SALB (3× 200 μg at 20 min intervals), IPR (20 μg, 20 μg and 40 μg at 20 min intervals) or placebo (PLA) (three doses at 20 min intervals) at 1 h, 12 h and 24 h post-MABA dose. The primary endpoint was maximal increase in FEV₁, from pre-dose bronchodilator (SABA/PLA), measured 15 min after each cumulative dose of SALB, IPR or PLA. Systemic pharmacodynamics (potassium, heart rate, glucose and QTc), adverse events and systemic pharmacokinetics were also assessed.ResultsThe additional bronchodilatory effects at 12 h and 24 h for both SALB and IPR were of a similar magnitude and statistically significant relative to PLA; mean differences (SE) (L) following MABA 400 dosing: 0.139 (0.023) after SALB at 12 h; 0.123 (0.022) after SALB at 24 h; 0.124 (0.023) after IPR at 12 h; 0.141 (0.021) after IPR at 24 h; and after MABA 1200 dosing: 0.091 (0.023) after SALB at 12 h; 0.126 (0.022) after SALB at 24 h; 0.055 (0.023) after IPR at 12 h; 0.122 (0.022) after IPR at 24 h. Any additional bronchodilator effects at 1 h were small and not clinically significantly different from PLA. There were small, non-clinically significant increases in mean heart rate after both MABA doses plus SALB, and decreased potassium levels in four patients after MABA 1200 plus SALB (×3) or PLA (×1) were observed but overall all treatments were well tolerated and raised no significant safety signals.ConclusionThe additional bronchodilation achieved following supratherapeutic doses of SALB and IPR on top of single doses of MABA 400 or 1200 was comparable for the two agents and neither were associated with any clinically relevant systemic pharmacodynamic effects other than the small transient hypokalemic effect in a 3 out of 41 patients receiving additional high dose salbutamol and MABA 1200. Either short-acting bronchodilator could potentially be used as rescue medication on top of MABA therapy.     

A supercritical fluid-based coating technology. 2: Solubility considerations

Solubility measurements of candidate coating materials have been performed in supercritical (SC) CO₂ so as to select appropriate coating materials for implementation of a solvent-free coating process previously described. Solubility of lipidic compounds such as waxes (paraffin, beeswax, Carnauba wax), pure triglycerides (tricaprin, trimyristin, tripalmitin, tristearin) and mixture of glycerides and fatty acid esters (Gelucire®) in SC CO₂ were evaluated in a static mode under different temperature and pressure conditions, ranging from 13–52°C and from 50–220 bar, whether the CO₂ was in its liquid or SC state. It was shown that the compounds which are mixtures of various components give rise to a selective extraction of the lower melting point components, as evidenced from thermal analysis of soluble and insoluble fractions of the coating materials.