Influence of Fine Grains on the Bending Fatigue Behavior of Two Implant Titanium Alloys

By means of the ultrasonic surface impact (amplitude of 30 μm, strike number of 48,000 times/mm²), nanograins have been achieved in the surfaces of both Ti6Al4V(TC4) and Ti3Zr2Sn3Mo25Nb(TLM) titanium alloys, mainly because of the dislocation motion. Many mechanical properties are improved, such as hardness, residual stress, and roughness. The rotating–bending fatigue limits of TC4 and TLM subjected to ultrasonic impact are improved by 13.1% and 23.7%, separately. Because of the bending fatigue behavior, which is sensitive to the surface condition, cracks usually initiate from the surface defects under high stress amplitude. By means of an ultrasonic impact tip with the size of 8 mm, most of the inner cracks present at the zone with a depth range of 100~250 μm in the high life region. The inner crack core to TC4 usually appears as a deformed long and narrow α-phase, while the cracks in TLM specimens prefer to initiate at the triple grain boundary junctions. This zone crosses the grain refined layer and the deformed coarse grain layer. With the gradient change of elastic parameters, the model shows an increase of normal stress at this zone. Combined with the loss of plasticity and toughness, it is easy to understand these fatigue behaviors.     

Intranasal immunization with protective antigen of Bacillus anthracis induces a long-term immunological memory response

Although intranasal vaccination has been shown to be effective for the protection against inhalational anthrax, establishment of long-term immunity has yet to be achieved. Here, we investigated whether intranasal immunization with recombinant protective antigen (rPA) of Bacillus anthracis induces immunological memory responses in the mucosal and systemic compartments. Intranasal immunization with rPA plus cholera toxin (CT) sustained PA-specific antibody responses for 6 months in lung, nasal washes, and vaginal washes as well as serum. A significant induction of PA-specific memory B cells was observed in spleen, cervical lymph nodes (CLNs) and lung after booster immunization. Furthermore, intranasal immunization with rPA plus CT remarkably generated effector memory CD4⁺ T cells in the lung. PA-specific CD4⁺ T cells preferentially increased the expression of Th1- and Th17-type cytokines in lung, but not in spleen or CLNs. Collectively, the intranasal immunization with rPA plus CT promoted immunologic memory responses in the mucosal and systemic compartments, providing long-term immunity.     

Transcranial Electrical Stimulation targeting limbic cortex increases the duration of human deep sleep

BackgroundResearchers have proposed that impaired sleep may be a causal link in the progression from Mild Cognitive Impairment (MCI) to Alzheimer's Disease (AD). Several recent findings suggest that enhancing deep sleep (N3) may improve neurological health in persons with MCI, and buffer the risk for AD. Specifically, Transcranial Electrical Stimulation (TES) of frontal brain areas, the inferred source of the Slow Oscillations (SOs) of N3 sleep, can extend N3 sleep duration and improve declarative memory for recently learned information. Recent work in our laboratory using dense array Electroencephalography (dEEG) localized the sources of SOs to anterior limbic sites – suggesting that targeting these sites with TES may be more effective for enhancing N3.MethodsFor the present study, we recruited 13 healthy adults (M = 42 years) to participate in three all-night sleep EEG recordings where they received low level (0.5 mA) TES designed to target anterior limbic areas and a sham stimulation (placebo). We used a convolutional neural network, trained and tested on professionally scored EEG sleep staging, to predict sleep stages for each recording.ResultsWhen compared to the sham session, limbic-targeted TES significantly increased the duration of N3 sleep. TES also significantly increased spectral power in the 0.5–1 Hz frequency band (relative to pre-TES epochs) in left temporoparietal and left occipital scalp regions compared to sham.ConclusionThese results suggest that even low-level TES, when specifically targeting anterior limbic sites, can increase deep (N3) sleep and thereby contribute to healthy sleep quality.     

镓合金用于牙体修复的临床应用研究

目的：观察镓合金作为一种新型的牙体修复材料在临床中的使用情况。方法：对48个牙体充填后经过6月、9月、12月、24月随访观察。结果：48个修复体中Ⅰ类洞40个、Ⅱ类洞6个、Ⅴ类洞2个，除4个修复体因充填后牙尖折断及乳牙替换而脱落，其余修复体均完整，无边缘折断或裂缝。优良率达95．5％。失败率4．5％。结论：镓合金对口腔黏膜及牙龈组织无刺激，无毒，无过敏反应，不污染环境，是一种良好的牙体修复材料。     

镍钛形状记忆合金环抱接骨板治疗桡骨近端1/3骨折

目的探讨治疗桡骨近端1/3骨折的理想内固定方法.方法 2001年8月～2004年4月,采用镍钛形状记忆合金环抱接骨板治疗24例桡骨近端1/3骨折.其中男19例,女5例.年龄16～48岁.摔伤9例,压砸伤5例,交通事故伤4例,直接暴力撞击伤3例,高处坠落伤3例.按照形状记忆合金环抱接骨板的安装方法进行骨折复位内固定.术后定期随访,观察骨折愈合及功能恢复情况.结果所有患者均获随访4～21个月,平均10个月.均无术中、术后并发症,切口Ⅰ期愈合;X 线片示骨折均于术后8～12周临床愈合,根据Anderson疗效标准,功能恢复优18例,良5例,可1例,优良率95.83%.结论应用镍钛形状记忆合金环抱接骨板治疗桡骨近端1/3骨折具有创伤小、操作简便安全、固定可靠、组织相容性好、并发症少等优点,有利于促进骨折愈合和肘、腕关节功能康复,是一种治疗桡骨近端1/3骨折的较好方法.     

学习困难儿童智力及记忆力特征分析

目的探讨学习困难儿童的智力、记忆力特征。方法学习困难(LD)根据ICD-10五条诊断标准,精神发育迟滞(MR)根据国际疾病分类第10版(ICD-10)诊断标准,分为实验组LD组;对照组a.正常组,b.弱智组。采用中国韦氏儿童智力量表进行智力测验,记忆力测验采用中国科学研究院编制的临床记忆量表。结果LD组与正常对照组在语言智商、操作智商、总智商[(86.23±10.65)分,(87.44±12.59)分,(84.09±13.96)分vs(102.27±10.21)分,(103.22±11.65)分,(103.28±9.88)分]及分测验值差异均有显著性(P<0.01);LD组儿童VIQ与PIQ相距一个标准差以上的比率明显高于对照组(2=9.29,P<0.01),也较MR对照组多(2=4.29,P<0.05)。LD组记忆商(MQ)明显低于正常对照组(P<0.01)。结论LD儿童智商、记忆商水平低于正常儿童,且存在明显智力结构发展不平衡。     

石杉碱甲和乙促进小鼠的空间辨别学习和记忆

石杉碱甲和乙是从石杉科石杉属植物蛇足石杉[Huperzia scrrata(Thunb.)Trev.]中分得的二个新生物碱。“Y”迷宫实验表明,ip Hup-A 0.075～0.125 mg/kg或Hup-B 0.4～0.8mg/kg,均能明显促进小鼠的空间辨别学习,并能显著预防CO₂产生的短时识别障碍,促进记忆保持和记忆再现。ig Hup-A 0.1～0.3 mg/kg或Hup-B 0.8 mg/kg也有促进学习的作用。促进作用Hup-A>Phys>Hup-B。剂量与效应曲线呈倒U型。     

复合矫治弓丝接头的力学性能及接头组织观察

目的　测试复合矫治弓丝接头的机械性能及分析接头、接头断口变化。方法　测试复合矫治弓丝接头的拉伸强度、剪切强度、扭转强度、弯曲形变残余角,TiNi形状记忆合金丝超弹性,扫描电镜观察及分析接头、断口组织变化。结果　复合矫治弓丝接头抗拉伸强度为32 0～36 0MPa ,剪切强度为2 2 0～2 5 0MPa ,抗扭转强度为30～4 0N·m、断裂时扭转角度不小于1 4 4 0°,弯曲形变残余角为1 2～1 7°;钎焊异质接头中TiNi形状记忆合金丝超弹性几乎没有破坏;接头钎料与TiNi形状记忆合金界面不存在扩散层,与不锈钢丝界面之间有一较宽的扩散层,接头断裂多发生在钎料与TiNi形状记忆合金超弹界面处,部分发生在钎缝中心。结论　复合矫治弓丝机械性能符合正畸临床要求,可应用于临床。     

Neuronal plasticity in memory and learning abilities: Theoretical position and selective review

Neural plasticity of modality-nonspecific and modality-specific memory and learning abilities pertains to fluid intelligence and crystallized intelligence, respectively. The limbic system with the novelty neurons of the hippocampus interacts with the prefrontal cortex optimization of the orienting reflex and voluntary attention. Brain-derived neurotrophic factor produced by novelty neurons of the hippocampus contributes to long-term memory formation and improves learning abilities in a wide range of disciplines. Synergistic combination of stimulation with “analytical-specific visual perceptual patterns” and “optimally high” physiological activation of the bilateral electrodermal system optimizes the limbic system and prefrontal cortex activity as demonstrated by enhanced prefrontal N450 ERPs to a memory workload paradigm. This is accompanied by improvements in auditory retention tasks, word memorization, higher school achievement and marks, and an amelioration of “analytical-specific perceptual skills” as measured by the Mangina-Test. Intracerebral ERPs to a memory workload paradigm contributed to the elucidation of limbic structures and neocortical sites involved in memory workload processes. The progressive degeneration of these same structures causes the gradual decline of memory functions observed in early Alzheimer's disease. Research findings indicate that ERPs elicited by a memory workload paradigm are sensitive markers for diagnosis, treatment and clinical follow-up of early Alzheimer's patients. In addition, ERPs provide objective measurement of cholinergic medication effects on cerebral functions involved in memory processes through neuropsychophysiological parameters.     

The aging brain, a key target for the future: The protein kinase C involvement

The brain represents the primary centre for the regulation and control of all our body activities, receiving and interpreting sensory impulses and transmitting information to the periphery. Most importantly, it is also the seat of consciousness, thought, emotion and especially memory, being in fact able to encode, store and recall any information. Memory is really what makes possible so many of our complex cognitive functions, including communication and learning, and surely without memory, life would lose all of its glamour and purpose. Age-associated mental impairment can range in severity from forgetfulness at the border with pathology to dementia, such as in Alzheimer's disease. In recent years, one of the most relevant observations of research on brain aging relates to data indicating that age-related cognitive decline is not only due to neuronal loss, as previously thought; instead, scientists now believe that age-associated functional changes have more to do with the dysfunctions occurring over time. Within this context a prominent role is certainly played by signal transduction cascades which guarantee neuronal cell to elaborate coordinated responses to the multiple signals coming from the outside and to adapt itself to the environmental changes and requests. This review will focus the attention on protein kinase C pathway, with a particular interest on its activation process, and on the role of protein-lipid and protein-protein interactions to selectively localize the cellular responses. Furthermore, information is emerging and will be discussed on the possibility of mRNA stabilization through PKC activation. This review will also approach the issue on how alterations of these molecular cascades may have implications in physiological and pathological brain aging, such as Alzheimer's disease.