It's all in the parameters: a critical analysis of some well-known negative studies on low-level laser therapy

OBJECTIVE: Scientific studies include references to historical studies on low-level laser therapy (LLLT) in general and to old studies on the specific subject in particular. Some studies are quoted often. It is fair to take a second look at these, since few people seem to have read them carefully, and others have read them only in the abstract form. This paper critically reviews the parameter pitfalls found in many of the classic "negative" studies. SUMMARY BACKGROUND DATA: A study of 1,200 papers on LLLT has resulted in 85 positive and 35 negative double-blind studies. The negative studies have been scrutinized carefully in an effort to pinpoint possible reasons for the failures. In the following, the majority are double-blind studies, but some non-blinded and animal studies have been included to give typical examples of pitfalls.     

Transient Temperature Analysis for Industrial AC Arc Furnace Bottom

Heat losses from the furnaces depend on the design and size. The surface heat loss from the bottom of an industrial AC electric arc furnace (EAF) possesses an important fraction of overall losses. So in this study the transient temperature variation at the bottom of the EAF was investigated. The transient temperature analysis was carried out using MATLAB computer program. T=T(r, t) for different bottom lining layers was depicted.     

Electrochemical Characterization of a Novel Mg70Al18Zn6Ca4Y2 Low Entropy Alloy in Different Aqueous Environments

In the present investigation, design and development of a novel Mg-based multicomponent low entropy alloy (Mg LEA-Mg₇₀Al₁₈Zn₆Ca₄Y₂) was carried out using Disintegrated Melt Deposition (DMD) technique. Various electrochemical techniques such as potentiodynamic polarization test (PDP) and electrochemical impedance spectroscopy (EIS) are used to investigate the electrochemical behaviour of the present Mg-LEA alloy at different molar concentrations in acidic (HCl), neutral (NaCl) and alkaline (NaOH, at different pH levels) solutions. The results show that, this alloy easily gets corroded with the increase of Cl⁻ ion concentration due to the breakdown of the Mg(OH)₂ passive layer in both acidic and neutral solutions. However, in the case of alkaline solution, the corrosion resistance of the alloy increases due to the formation of a stable Mg(OH)₂ layer along with AlMg₂Zn and Al₂Y phases, which is more stable than αMg. The ranking of Mg-LEA alloy’s corrosion rate is as HCl> NaCl> NaOH. The impedance measurements have correlated well with polarizations results and the data obtained according to the equivalent circuit provide insights between electrode and electrolyte interface. Through SEM analysis, pitting corrosion was observed in Mg-LEA alloy in acidic and neutral solutions and their chemical compositions were obtained using energy-dispersive X-ray spectroscopy (EDS).

     

Ischemic-reperfused rat skeletal muscle: the effect of vasoactive intestinal peptide (VIP) on contractile force, oxygenation and antioxidant enzyme systems

The effect of vasoactive intestinal peptide (VIP) on the nerve-stimulated contraction, tissue oxygenation, lipid peroxidation and antioxidant enzymes activities-superoxide dismutase and catalase was investigated in the rat gastrocnemius muscle exposed to 4 h ischemia-4hr reperfusion. Ischemia caused significant decrease in muscle contractile force, oxygenation and superoxide dismutase enzyme activity. Reperfusion of ischemic muscle increased the muscle contractile force and restored the tissue oxygenation to the baseline level. Superoxide dismutase and catalase activities of reperfused muscle increased significantly. However neither ischemia nor reperfusion affected gastrocnemius muscle malondialdehide (MDA) levels. VIP administration at the onset of reperfusion significantly increased skeletal muscle contractile force and tissue oxygenation even higher than baseline and reperfusion values. VIP also normalized the increased superoxide dismutase and catalase activities of reperfused skeletal muscle. In conclusion, VIP, acting as a powerful antioxidant and preserving contractile machinery seems to be a promising endogenous peptide that can salvage the skeletal muscle from severe ischemia-reperfusion injury.     

层次结构文档下支持权限管理的实时协同技术研究

针对传统实时协同系统中各站点之间无约束操作的缺点,提出采用权限分工的方式来支持不同团队之间的文档管理。给出了支持权限管理的层次结构文档的形式化定义,描述了用户角色设置过程,定义了权限及权限操作格式,讨论了站点ID的设置及初始化过程,并提出采用改进的地址空间转换算法来保证权限操作在各分布式站点的正确执行。分析了改进算法的效率提升,并通过其在Co-AutoCAD中的应用证实了策略的有效性。     

The Effect of Iron Content on Microstructure and Mechanical Properties of A356 Cast Alloy

In the present study, microstructure and mechanical properties of A356 alloy including various amounts (0.2 to 1.2 wt pct) of iron were investigated. The alloys were produced by conventional gravity sand casting method. In order to determine the effect of iron addition to A356, optical and scanning electron microscopes (SEM/EDS) were used for microstructural examinations, and X-ray diffraction (XRD) analysis was carried out for phase characterization. Tensile tests were also conducted in order to determine effect of the Fe content on mechanical properties. It was found that as the Fe content of A356 was increased, the secondary dendrite arm spacing (SDAS) was decreased and the morphology of Al-Si eutectic became finer. From XRD examinations, different iron-based intermetallic compounds (β-Al₅FeSi and α-Al₈Fe₂Si) formations were observed. It was also observed that as iron content increased, α-Al₈Fe₂Si intermetallic was transformed into β-Al₅FeSi intermetallic. The tensile test results revealed that tensile strength and elongation values were reduced by increasing Fe content. It was also determined that β-Al₅FeSi intermetallics were more negatively effective on tensile strength than α-Al₈Fe₂Si intermetallics.     

快锻压机上横梁拓扑优化设计

选择大型快锻压机的上横梁为研究对象,以其柔度最小为优化目标,静态特性及可制造性为约束条件,进行拓扑优化分析。再根据上横梁的装配要求及拓扑优化结果进行三维模型重建,并对重建的模型进行有限元仿真分析,得到最优的能用于实际生产的上横梁模型。通过优化分析,上横梁较原模型减重6.3%,达到了轻量化设计的目的,节约了经济成本,可为之后产品的优化升级提供参考。     

核电项目BOP施工图设计进度量化评估方法研究

针对核电厂工程建造设计管理中设计进度评价这一难点,结合广东台山核电一期工程BO P施工图设计进度管理实践,对定量加权计算法、专业访谈法进行分析和比较。将这两种评价方法应用在EPR核电项目BOP施工图设计进度管理中,形成具体操作流程。这两种评价方法是对以设计成品文件交付结果为导向的设计进度管理方法的延伸和拓展。