Modified phacoemulsification in situ

We describe a phacoemulsification technique for cataracts in eyes with anticipated weak zonular apparatus. After central sculpting, a crater 90% deep is made. A horizontal fracture is created with the phaco probe and chopper. The nucleus is chopped, dividing the inferior hemisection into 2 pie-shaped pieces, which are then emulsified. Without rotating the nucleus, a groove is made at the superior hemisection and a vertical fracture created with the chopper. The bevel of the phaco probe is then turned down to emulsify each quadrant separately. This technique is especially useful in eyes with weakened zonular apparatus such as those with hypermature cataract, uveitis, long-standing glaucoma, trauma, retinitis pigmentosa, and operated retinal detachments.     

Evaluation of in situ fracture versus phaco chop techniques

PURPOSE: To quantify and compare the phaco time required using in situ nucleofracture and phaco chop techniques. SETTING: Center for Research on Ocular Therapeutics and Biodevices and Miyake Laboratory, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA. METHODS: Thirty human eyes obtained postmortem were randomly divided into 2 groups of 15 eyes each. In situ nucleofracture or phaco chop was performed in each group. The phaco time required for each technique was determined. RESULTS: The mean phaco time was 0.91 minutes +/- 0.37 (SD) for the phaco chop and 1.56 +/- 0.89 minutes for the in situ fracture technique (P < .015). CONCLUSIONS: The phaco chop technique reduced phaco time and total phaco power consumed during phacoemulsification without imposing a risk of intraoperative complications.     

Effect of opioid blockade on insulin and growth hormone (GH) secretion in patients with polycystic ovary syndrome: the heterogeneity of impaired GH secretion is related to both obesity and hyperinsulinism

Amplitude-coded color Doppler sonography (ACD) has become an useful adjunct to gray-scale US and conventional color Doppler sonography (CD) for the assessment of vascular diseases and pathologic conditions that might affect or alter tissue vascularization or perfusion. Basically, all US units that generate conventional color Doppler information through autocorrelation technique are capable of displaying ACD. This technique is also referred to as power Doppler, amplitude-mode color Doppler US, color Doppler energy (CDE), or US angiography. Amplitude-coded color Doppler sonography has already emerged as a valuable adjunct to conventional CD, particularly for evaluating flow in parts of the body where CD signal is weak because of slow flow, small blood vessels, or both.     

铝合金表面脉冲电磁场对半连续铸造晶粒的细化

采用一种新型熔体表面脉冲电磁技术对7A04铝合金半连续铸造凝固组织细化处理,分析脉冲电磁场对凝固组织及性能的影响.引入势能的观点,探讨脉冲磁能作用下的晶体形核动力学及初生晶核运动形式.结果表明,经表面脉冲电磁场处理后,凝固组织由晶粒尺寸粗大的玫瑰结构转变为细小且圆整的球状结构,铸锭心部及边部晶粒尺寸分别下降22.7%和14.2%,强度、塑性均有提高.动力学分析认为,脉冲电磁能降低体系形核所需的临界吉布斯自由能是增加形核率的重要原因,同时可导致初生α-Al运动的势能增加,促使初生α-Al颗粒优先到达稳定位置.      

Silicon PV Cell Production on the Moon

A concept has been developed for the production of photovoltaic energy collection systems on the Moon by vacuum deposition directly onto the lunar surface. Using this technique it would be possible to quickly install quite large capacities of power on the Moon at relatively low cost. Most of the material required for photovoltaic devices is readily available on the Moon, and taking production machinery to the Moon can further lower the cost of power if the machinery can be operated for long periods of time. Low-cost energy on the Moon could enable a wide range of activities including support of robust human outposts, production of propellants for use on the Moon or for export, production of a wide range of other materials for use in space, and beaming of energy from the Moon to space and to Earth. A proposed strategy by which lunar power can be developed in the near future is closely connected to the establishment of a human outpost on the Moon.     

Space Solar Power: A Major New Energy Option?

Large space solar-power systems have intermittently been a topic for consideration during the past 30 years. However, the last major studies in the United States on these concepts were conducted in the late 1970s. After two decades of relative inactivity, large-scale space solar power (SSP), including the generation of solar power in space for transmission to terrestrial markets, has recently reemerged as a potential energy option. This occurrence is timely because global energy demand continues to grow dramatically while environmental concerns increase. Demand for power in space is also likely to increase during the same time frame. A wide range of technology advances would be needed to enable such systems. In addition to very low cost space transportation and highly efficient and high voltage solar arrays, significant developments must also take place in technologies such as wireless power transmission, large space structures, robotic assembly and maintenance, and others. However, recent NASA studies and focused research and development progress in a number of key areas suggest that such systems are technically feasible. This paper presents an overview of the subject of space solar power, including results of recent NASA activities.     

Prevention of coronary heart disease in clinical practice. European recommendations revised and reinforced

We report a case in which a severe corneoscleral burn occurred during phacoemulsification surgery. The equipment-tuning process was uneventful and routine surgery was expected. Severe tissue injury occurred because the anterior chamber collapsed momentarily and the phaco tip touched corneoscleral tissue. We discuss mechanisms by which this type of injury may occur and the likely cause in our case. We also suggest methods to reduce the incidence.     

Melting cathode copper—A case study in process energy efficiency

Melting of cathode copper in the reverberatory, the electric are furnace and the Asarco shaft furnace is analyzed in order to evaluate specific capacity, process fuel equivalent and the energy efficiency for each process. The Asarco furnace possesses considerably higher specific capacity and energy efficiency than the reverberatory as a result of the basic design for counter-current flow. The electric are furnace has lower energy efficiency than the reverberatory (with a waste-heat boiler) because the inefficiency in generation of electric power from fuel more than outweighs the very low heat loss from the electric furnace.     

Energy reflectance in the ear canal can exceed unity near spontaneous otoacoustic emission frequencies

There is some controversy in the literature over whether the so-called "active mechanism" or "cochlear amplifier" is actually a power amplifier that can produce an output signal with more power than its input, or whether it simply minimizes dissipative losses within the cochlea without providing an actual power gain greater than unity. A corollary of this controversy is whether spontaneous otoacoustic emissions (SOAEs) represent the output of a nonlinear oscillator mechanism, i.e., a power amplifier which can produce an oscillatory output signal in the absence of an input oscillatory signal, or whether they represent the output of a noise-driven, passive, nonlinear system. This paper describes measurements of energy reflectance, and acoustic impedance in the ear canals of human subjects with strong SOAEs. The reflectance, and the resistive and reactive parts of the acoustic impedance, all show a frequency fine structure which correlates with SOAE frequencies, and which becomes more pronounced at low stimulus levels. In some ears at some SOAE frequencies, energy reflectance exceeds unity, and correspondingly, acoustic resistance is negative. This result demonstrates that there is a power gain at these frequencies: The power reflected from the cochlea to the ear canal exceeds the power incident. It is also consistent with the theory that these SOAEs are produced by a nonlinear oscillator mechanism in the cochlea.     

矿山企业节能与无功功率补偿

功率因数的高低关系到电力网中的功率损耗和电能损耗,提高电力系统的功率因数,有利于矿山企业节能.文中分析了影响电网功率因数的主要因素、低压电网无功补偿的常用方法及无功补偿的效益.     

Use of power Doppler in pediatric neurosonography: a pictorial essay

In pediatric neurosonography, conventional color Doppler imaging has been the primary adjunct to routine gray-scale imaging. Power Doppler sonography is a relatively recent development that does not have the limitations of conventional color Doppler ultrasound. The power Doppler technique measures the energy of moving red blood cells instead of the velocity and direction of flow. Advantages of this technique include increased sensitivity for identifying flow in slow-flow states, more complete evaluation of a vessel, and more accurate evaluation of the course of the vessel. Power Doppler sonography is helpful in evaluation of the neonatal brain in a variety of clinical situations: identifying the exact locations of extraaxial fluid collections, differentiating intraventricular clot from normal choroid plexus, detecting intraventricular hemorrhage, and demonstrating asymmetries in cerebral perfusion. However, in certain difficult cases, use of both conventional color Doppler sonography and power Doppler sonography produces increased diagnostic accuracy because these techniques furnish complementary information.     

我国电弧炉炼钢技术的进展讨论

10年来我国电弧炉炼钢技术在产量、装备技术(大型化、高的技术经济指标)、高效化技术(超高功率供电、辅助能源、炉料多元化、减少非通电时间、废钢预热、连续化生产)和洁净化技术方面均取得了显著进展。但是废钢资源短缺、电力不足和能源结构不合理等因素制约了我国电弧炉炼钢的进一步发展。文中讨论了我国电弧炉炼钢发展的重点(炉料多样化、合理供电、能量多样化、余热利用和绿色环保)和前瞻(低碳经济洁净钢生产)。     

Peroperative microbial contamination of anterior chamber aspirates during extracapsular cataract extraction and phacoemulsification

BACKGROUND: The normal conjunctival flora is one of the main sources of intraocular contamination during cataract surgery. The theory that the positive anterior chamber (AC) pressure during phacoemulsification (phaco), and the smaller wound utilised, might reduce the rate of contamination was studied. METHODS: The peroperative AC aspirates of 210 consecutive patients undergoing cataract surgery were assessed. In group 1, 100 patients underwent a standard extracapsular cataract extraction (ECCE). In group 2, 110 patients underwent phacoemulsification of the crystal-line lens through a scleral tunnel. AC aspirates from the Simcoe irrigation/aspiration cannula (group 1) and phaco probe (group 2) were collected and microbiological studies performed after direct and enrichment cultures. RESULTS: There were 29 (29%) positives in the ECCE group compared with 22 (20%) positive cultures from AC aspirates in the phaco group. Coagulase negative staphylococcus (CNS) was the commonest contaminant in both groups. CONCLUSION: Although there was a higher rate of AC contamination during ECCE, the difference was not statistically significant (p > 0.10, chi 2 = 2.31).     

探索“低碳能源”在新型城镇化中的作用

新型城镇化进程中如何构建低碳、安全的能源体系,是目前新型城镇化建设中易被忽略的问题。人们习惯于关注汽车节能或者电力系统;其实我国每年在建筑领域内所消耗和损失的能源十分惊人。近十来年我国建筑量一直在世界排名第一,按照目前能耗水平,到2020年我国仅仅在空调高峰负荷能耗就相当于10个三峡电站满负荷输出。然而,建筑节能的前景却十分广阔和诱人,中国与欧洲均在建筑领域取得一系列阶段性成果。本文试图通过比较国内外建筑节能领域的差异性,来寻找适合我国新型城镇化进程中"低碳能源"建设的有效途径。     

基于储能的柴油发电机组效率提升研究

大部分矿山企业由于地处供电网络难以覆盖或经济欠发达的无电地区,且用电负荷大,采用柴油发电机组孤网自供电模式,存在发电效率低、发电成本高、运维工作量大、环境污染等问题.利用储能系统的特点,结合海外矿山企业的需求,搭建新型的储能柴发供电网络,介绍了其网络架构、系统组成以及工作原理,并结合项目实例,说明基于储能的柴油发电机组...     

Finding Critical Nucleus in Solid-State Transformations

Based on the phase-field total free energy functional and free-end nudged elastic band (NEB) algorithm, a new methodology is developed for finding the saddle-point nucleus in solid-state transformations. Using cubic → tetragonal transformations in both two and three dimensions as examples, we show that the activation energy and critical nucleus configuration along the minimum energy path (MEP) can be determined accurately and efficiently using this new approach. When the elastic energy contribution is dominant, the nucleation process is found to be collective with the critical nucleus consisting of two twin-related variants. When the elastic energy contribution is relatively weak, the critical nucleus consists of a single variant, and the polytwinned structure develops during growth through a stress-induced autocatalytic process. A nontrivial two-variant critical nucleus configuration is observed at an intermediate level of the elastic energy contribution. This general method is applicable to any thermally activated process in anisotropic media, including nucleation of stacking faults and dislocation loops, voids and microcracks, and ferroelectric and ferromagnetic domains. It is able to treat nucleation events involving simultaneously displacive and diffusional components, and heterogeneous nucleation near pre-existing lattice defects. This article is based on a presentation given in the symposium entitled “Solid-State Nucleation and Critical Nuclei during First Order Diffusional Phase Transformations,” which occurred October 15–19, 2006 during the MS&T meeting in Cincinnati, Ohio under the auspices of the TMS/ASM Phase Transformations Committee.     

钢静态再结晶的蒙特卡洛模拟

应用蒙特卡洛技术模拟了钢的静态再结晶及晶粒长大过程，模拟假设这一过程是各向同性形核且为饱和形核，并考虑了晶粒不同储存能（Ｈ／Ｊ＝５和Ｈ／Ｊ＝３）条件下的形核机制，模拟结果和理论预测相吻合。     

提高工矿企业供用电系统运行经济效益的思考

加强用电企业用电管理,既是贯彻落实国家节能减排政策的具体体现,又是降低企业生产成本,增强企业市场竞争力,增强企业创利能力的有效措施。本文介绍了科学选择企业供电电压等级和主变压器容量的方法,探讨了企业加强节电技术和用电管理的措施,目的是与同行共同探讨提高工矿企业供用电系统运行的经济效益。     

利用冶炼中高温烟气进行余热发电

介绍了二次利用冶炼生产中高温烟气,通过余热锅炉产生蒸汽带动抽汽凝汽式饱和蒸汽透平汽轮发电组,进行余热发电的过程。该项目的模式使能源得到充分利用,符合国家要求低碳环保节能减排方针。进一步提高企业社会效益和经济效益。     

微电脑自动功率因素集中补偿装置的应用

本文主要探讨微电脑自动功率因数集中补偿控制器及其成套装置对工矿企业厂房低压供电系统进行无功功率自动补偿以提高功率因素,减少线路损耗,节约电能和送变电设备器材,提高供电质量和保证用电安全。侧重论述低压供用电系统无功就地补偿与微电脑自动功率因素补偿的互补性;微电脑自动功率因素补偿在三分厂16号厂房动力变压器上应用的可行性及实施的方案。