攀钢PD3热处理钢轨及展望

攀钢在研究出含钒舍金PD3热轧钢轨基础上，先后成功研究了该钢轨的双频电感应加热、压缩空气欠速淬火技术和钢轨轧后直接淬火技术，生产了PD3离线和在线热处理钢轨。钢轨抗拉强度分别为Rm≥1275MPa和Rm≥1175MPa，延伸率均为Ａ５≥10％。在相同线路条件的小半径曲线上，PD3离线热处理钢轨的使用寿命比U71Mn和U74热轧钢轨提高三倍以上，PD3在线热处理钢轨的使用性能也明显优于U71Mn钢轨，与英国U78处理钢轨使用性能相当。     

PD3重轨钢试制

本文主要总结了PD3重轨钢的试炼情况.结果表明:通过铁水预处理-转炉冶炼-LF精炼-vD真空处理-连铸工艺-轨梁轧制生产的PD3钢轨各项性能达到了GB2585-81标准要求.     

Effects of the dopamine D3 antagonist PD 58491 and its interaction with the dopamine D3 agonist PD 128907 on brain dopamine synthesis in rat

The dopamine (DA) D3 receptor antagonist PD 58491 [3-[4-[1-[4-[2-[4-(3-diethylaminopropoxy)phenyl]benzoimidazol++ +-1-yl-butyl]-1H-benzoimidazol-2-yl]phenoxy]propyl]diethylamine] bound with high affinity and selectivity to recombinant human DA D3 versus D2L and D4.2 receptors transfected into Chinese hamster ovary cells: Ki values of 19.5 nM versus 2,362 and >3,000 nM, respectively. In contrast, the putative DA D3 receptor antagonist (+)-AJ76 displayed low affinity and selectivity for D3 versus D2L and D4.2 receptors (91 nM vs. 253 and 193 nM, respectively). In vitro, PD 58491 (1 nM-1 microM) exhibited D3 receptor antagonist activity, reversing the quinpirole (10 nM)-induced stimulation of [3H]thymidine uptake in D3 CHOpro-5 cells, but did not have any significant intrinsic activity by itself in this assay. PD 58491 did not decrease the gamma-butyrolactone-induced increase in DA synthesis (L-3,4-dihydroxyphenylalanine accumulation) in rat striatum, indicating that the compound possessed no in vivo DA D2/D3 receptor agonist action at DA autoreceptors. PD 58491 (3-30 mg/kg, i.p.) generally did not alter DA or serotonin synthesis in either the striatum or mesolimbic region of rat brain. The D3-preferring agonist PD 128907 decreased DA synthesis in striatum and mesolimbic regions, and this effect was attenuated by pretreatment with PD 58491. These findings support the hypothesis that DA D3 autoreceptors may in part modulate the synthesis and release of DA in striatum and mesolimbic regions.     

提高PD3钢轨力学性能的实践

针对鞍钢模铸生产的PD3钢轨较U7lMn钢力学性能合格串偏低的情况，对可能影响钢轨力学性能的化学成分、钢轨氢含量、金相组织、非金属夹杂物等方面进行综合分析，认为控制非金属夹杂物的种类和数量是提高力学性能的主要手段，并通过调整生产工艺达到了这一目的。     

钒对PD3钢珠光体组织形态的影响

对钒在珠光体组织转变中的作用进行了研究，结果表明：钒在PD3钢中可起到细化珠光体，使渗碳体片变得不规则的作用，但钒对珠光体团大小影响较小。当PD3钢中钒含量增加到0．33％时，碳氮化钒将大量析出，并使珠光体片间距反常粗化，对韧性不利。     

PD3钢轨钢接触疲劳行为研究

在最大接触应力为１３４１ＭＰａ、滑差率为１０％及油润滑的试验条件下，对在线全长余热淬火、热轨及稀土处理三种状态的ＰＤ３钢轨钢的接触疲劳行为进行了测定。通过对失效试样的分析，对钢轨钢的接触疲劳机制进行了探讨。试验结果表明，在线全长余热淬火工艺大大提高了ＰＤ３钢轨钢的接触疲劳抗力。     

PD3钢轨钢接触疲劳变形组织的TEM观察

在透射电镜下观察接触疲劳失效后不同状态的ＰＤ３钢轨钢的变形组织。结果表明，接触疲劳变形组织的主要特点是：珠光体片层间距减小，珠光体团被剪切分割成亚团，先析铁素体内形成位错胞结构；铁素体／渗碳体界面上存在高的位错密度；珠光体中渗碳体片发生变形与断裂。同时对珠光体片层间距与变形组织的关系进行了分析讨论。     

Effects of G6PD overexpression in NIH3T3 cells treated with tert-butyl hydroperoxide or paraquat

The major physiological role of glucose-6-phosphate dehydrogenase (G6PD) is to provide NADPH, which is required for reductive biosynthesis and for detoxification of free radicals and peroxides in mature red blood cells. To study the function of G6PD in non-erythroid cells, we examined the sensitivity of NIH3T3 cells transfected with a plasmid containing human G6PD cDNA to tert-butyl hydroperoxide (TBH) and paraquat. Two transfected clones which had a sixteen-fold (H7 clone) and six-fold (H6 clone) increase in their intracellular G6PD activity were compared with control cells transfected with a vector alone. Cells with high-level expression of human G6PD were 2.3 (H6) to 3.7 (H7) times more resistant to TBH than control cells. The antioxidant (anti-TBH) abilities in H6 and H7 cells were revealed by (1) a significant increase in the intracellular level of NADPH and glutathione, (2) a reduction of fluorescent intensity of the oxidant-sensitive dye, 2',7'-dichlorofluorescin diacetate, and (3) a significant reduction in the production of oxidized adducts generated by lipid peroxidation. In contrast, cells overexpressing G6PD were very sensitive to paraquat, a superoxide-producing herbicide. The concentrations of paraquat required to produce a 50% decrease in cell viability of H7, H6 and control cells were 0.80 mM, 1.14 mM, and 2.19 mM, respectively. The cytotoxicity of paraquat correlated with the expression level of NADPH in the cells. In this study, overexpression of human G6PD in NIH3T3 cells had different effects on the toxicity of TBH vs. paraquat. Reduction of NADP+ to NADPH by G6PD protects cells from oxidative damage by TBH, but appears to enhance the toxicity of paraquat.     

Pharmacological characterization of PD 152255, a novel dimeric benzimidazole dopamine D3 antagonist

152255 (E-1,1'-(2-butene-1,4-diyl)bis[2-[4-[3-(1-piperidinyl)propoxy]-phe nyl]-1H-benzimidazole]) exhibited high affinity (Ki = 12.7 nM) for human dopamine (DA) D3 receptors expressed in CHO K1 cells but not for DA D2L receptors (Ki = 565 nM), DA D42 or DA D1 receptors (Ki > 3 microM) and a number of other neurotransmitter receptors. Affinity for human muscarinic receptors was seen in vitro but no functional muscarinic agonist and/or antagonist action was observed in vivo. Antagonist activity at DA D3 receptors was demonstrated by blockade of quinpirole-stimulated [3H]-thymidine uptake in D3 transfected cells, an effect that was 28-fold more potent than in D2-transfected cells. Unlike classical DA D2 antagonists, PD 152255 did not increase rat brain DA synthesis and it increased locomotion in habituated rats. However, like antipsychotics, PD 152255 reduced locomotor activity in mice and reduced spontaneous and amphetamine-stimulated locomotion in nonhabituated rats. These results demonstrate that PD 152255 is a DA D3 antagonist that may have antipsychotic activity.     

Surgical interventions in the treatment of Parkinson's disease (PD) and essential tremor (ET): medial pallidotomy in PD and chronic deep brain stimulation (DBS) in PD and ET

Surgical treatments for PD and ET are promising. Medial Pallidotomy, the surgical lesioning of the pallidum, often improves symptoms of long-standing PD. We enrolled twenty-seven late stage PD patients for unilateral medial pallidotomy who were then assessed by the Core Assessment Program for Intracranial Transplantation (CAPIT) protocol. One year after surgery persistent improvement was seen contralateral to the lesion in the following features: drug-induced dyskinesias (92%), akinesia (38%), rigidity (51%), and tremor (42%). Complications included transient dysarthria (7 patients), facial weakness (9 patients), limb weakness (1 patient), swallowing problems (4 patients) and intracerebral haemorrhage (1 patient). Thalamic DBS may improve tremor in PD and ET patients. Therefore, we enrolled fifteen patients (9 PD and 6 ET patients) with disabling tremor, unresponsive to medication. They were assessed by the United Parkinson's Disease Rating Scale (UPDRS) and the Tremor Rating Scale (for PD and ET patients, respectively). Three months after surgery, limb tremor contralateral to stimulation improved by 71% in PD patients and 76% in ET patients. Complications included transient paresthesias (all), confusional state (1 patient) and intracerebral bleed (1 patient). Unilateral medial pallidotomy safely improves some Parkinsonian symptoms contralateral to the lesion. Thalamic DBS may effectively and safely improve contralateral limb tremor in PD and ET.     

PD103喂料泵减速机故障诊断

通过对Pd103喂料泵减速机的状态进行监测,综合分析其劣化趋势、瀑布图、时域、频域及包络解调等多种信号分析,对Pd103喂料泵减速机的齿轮故障做出准确诊断,避免了重大事故的发生,说明实行设备状态监测的重要性。     

In vitro activities of meropenem, PD 127391, PD 131628, ceftazidime, chloramphenicol, co-trimoxazole, and ciprofloxacin against Pseudomonas cepacia

In a study of 110 Pseudomonas cepacia isolates from patients without cystic fibrosis, the in vitro potencies of three new compounds, meropenem, PD 127391, and PD 131628, were comparable to those of ceftazidime and ciprofloxacin and exceeded those of chloramphenicol and co-trimoxazole. The MICs of ceftazidime, ciprofloxacin, meropenem, and the PD compounds for 90% of strains tested were < or = 4 micrograms/ml, whereas they were 32 micrograms/ml for chloramphenicol and co-trimoxazole. Data for 20 isolates from patients with cystic fibrosis indicated that the isolates were less susceptible to all seven antibiotics tested, with the most active compounds being meropenem and PD 127391.     

Clozapine and PD149163 elevate prepulse inhibition in Brown Norway rats.

Unmedicated schizophrenia patients exhibit deficits in prepulse inhibition (PPI) of the acoustic startle response. Similar deficits can be induced in rodents via a variety of manipulations and these deficits can be reversed by antipsychotics. Brown Norway (BN) rats exhibit natural PPI deficits under certain parametric conditions. We treated BN rats with haloperidol or clozapine to determine if the BN rat is a useful animal model with predictive validity for the effects of antipsychotics. In addition, we also tested PD149163, a neurotensin-1 receptor agonist, which has been shown to exhibit antipsychotic-like effects in several other animal models. BN rats received subcutaneous injections of either saline or one of two doses of haloperidol (0.5 mg/kg, 1.0 mg/kg), clozapine (7.5 mg/kg, 10 mg/kg) or PD149163 (1.0 mg/kg, 2.0 mg/kg). PPI was measured in startle chambers 30 min after injection. Systemic clozapine and PD149163 but not haloperidol facilitated PPI in BN rats (p