Number Of Long Periods Research Articles

Progresses in the treatment of exudative age-related macular degeneration with anti-vascular endothelial growth factor drugs

Intravitreal injections of anti-vascular endothelial growth factor (anti-VEGF) drugs, including monoclonal antibodies (such as bevacizumab and ranibizumab) and fusion protein agents (such as aflibercept and conbercept) have been proven to be effective in the treatment of wet age-related macular degeneration (wAMD). However, there are still some patients with poor efficacy, such as no response to initial treatment or poor response, and even relapse during the course of treatment. In view of the different targets and molecular characteristics of anti-VEGF drugs, the switch of anti-VEGF drugs and the adjustment of delivery pattern, dosages and intervals have been the strategies to cope with the poor efficacy in clinic. However, there are some differences in the results of current studies. Overall, the recovery of retinal anatomical outcome achieves more benefits, and it is relatively difficult to improve visual acuity. To determine which regimen would get the biggest benefits, a large number of randomized controlled clinical trials and long study period will be needed. Key words: Wet macular degeneration/drug therapy; Angiogenesis inhibitors/therapeutic use; Antibodies, monoclonal, humanized/therapeutic use; Review

Compressive anisotropy of extruded Mg–Dy–Zn alloy sheet

Compressive anisotropy of extruded Mg–2Dy–0.5Zn (mole fraction, %) alloy sheet was investigated. The alloy sheet was mainly composed of α-Mg, (Mg, Zn)xDy phase and a large number of long period stacking ordered (LPSO) phases distributed along the extrusion direction. The compressive experimental results show that the alloy sheet exhibits an obvious compressive anisotropy. The compressive strength of the specimen in the extrusion direction (ED) is higher than those of the specimens in the transverse direction (TD) and 45° inclined to the extrusion direction. The compressive yield strength (CYS), ultimate compressive strength (UCS) and compressive strain of the specimen in the ED are 274.65 MPa, 518.94 MPa and 12.93%, respectively. The compressive anisotropy is mainly attributed to the distribution of LPSO phase and formation of fiber texture in the deformed grains.

Deformation behavior of an extruded Mg–Dy–Zn alloy with long period stacking ordered phase

Abstract Deformation behavior of an extruded Mg–2Dy–0.5Zn (at%) alloy was investigated under uniaxial tensile test at a range of strain rates of 3×10−5–3×10−1 s−1 and temperature ranging from room temperature (RT) to 300 °C. The microstructure of the alloy was mainly composed of α-Mg, (Mg, Zn)xDy particle phase and a large number of long period stacking ordered (LPSO) phases. The tensile testing results indicated that strain rate sensitivity exponent (m) generally increased with increasing temperature and decreasing strain rate. Interestingly, m exhibited two different values in log σ − log e curves at 300 °C, indicating that the plastic deformation mechanism of the alloy occurred to change. The surface and microstructure observations of the tensile specimens after tension revealed that the deformation behavior of the alloy was similar to that of the metal matrix composites, where the load transferred from the Mg matrix to the LPSO phase at low temperatures (RT~200 °C) under different strain rates and at 300 °C under high strain rates, while the grain boundary sliding accommodated by dislocation slip dominated the whole deformation behavior at 300 °C under low strain rates. The alloy exhibited a quasi-superplastic deformation with an elongation-to-failure of 105% at 300 °C and 3×10−5 s−1. The quasi-superplastic deformation was attributed to the stable grains retained by the precipitation of the LPSO phase with good thermal stability in grain interior at an elevated temperature.

Effect of long period stacking ordered (LPSO) structure on the damping capacities of Mg–Cu–Mn–Zn–Y alloys

The microstructure and damping capacities of the Mg–3%Cu–1%Mn–1.8%Zn–x%Y alloys have been researched and compared synthetically. This study showed long period stacking ordered (LPSO) structure is conducive to yield strength and damping capacities on the whole. The Mg–3%Cu–1%Mn–1.8%Zn–12.5%Y can be classified as high damping metals (Q−1⩾0.01) when strain is above 1.1×104. When a number of long period stacking ordered structure are observed, the phenomenon both its damping capacities and yield strength increase breaks the contradiction between damping capacities and mechanical properties in magnesium alloys. The damping capacities of those alloys cannot only be explained by the Granato–Lücke theory and a new damping mechanism that depends on frequency has been found. Thereby, it may introduce a new method to produce magnesium alloys with high damping capacity and high strength.

Association between numbers of long periods with sustained low-level trapezius muscle activity and neck pain

The purpose of this prospective cohort study was to evaluate relationships between sustained low-level muscle activity (SULMA) in the neck and pain after 1 year among machine operators of forest harvesters (n = 19), forwarders (n = 20) and forest researchers (n = 20). Surface electromyography of the right upper trapezius muscle was measured during one working day. Continuous muscle activity (SULMA periods) were analysed in predetermined time intervals. Neck pain was assessed by the Borg's category-ratio scale and the Standardized Nordic Questionnaire (dichotomised into pain duration ≤30 or >30 d). Harvesters reported significantly more pain than researchers. A higher number of long SULMA periods >8 min duration increased the risk of neck pain >30 d during the successive year (odds ratio 3.0, 95% CI 1.2–7.8). Perceived personal economy above average was associated with less pain, while other potential confounders or intermediate variables were not significant. Low-level trapezius muscle activity in periods longer than 8 min may constitute a risk for neck pain.

Dislocation structure and energy of high angle [001] twist boundaries: A computer simulation study

High angle (001) twist boundaries have been frequently investigated experimentally and the presence of grain boundary dislocations (gbd's) and associated cusps in the dependence of the boundary energy on misorientation, is in this case well established. However, in previous computer simulations of these boundaries neither localised gbd's nor distinct energy cusps have been identified. The principal aim of the present study is to clarify this discrepancy between observations and computer modelling. For this urpose the structure and energy of a number of long period (high ∑) twist boundaries with misorientations very close to ∑ = 5 have been calculated using empirical pair and n-body potentials to describe interatomic forces. Furthermore, an isolated gbd embedded into a ∑ = 5 boundary has been modelled. Well defined cusps at ∑ = 5 misorientation and localised gbd's have been found but the reference ∑ = 5 structure is always the lowest energy structure which, in general, does not possess the symmetry of the coincidence site lattice. The misorientation dependence of the boundary energy is then discussed using a Read-Shockley type model. The cusps are always very shallow and may have an uncoventional shape which is related to the dependence of the elastic energy on misorientation that is not the same for twist and tilt boundaries, contrary to what is usually assumed. Finally, some remaining discrepancies between observed types of gbd's and those found in the present study are discussed in the light of the previously proposed multiplicities of boundary structures.

The sensitivity of dependence of large scale flow characteristics in a four-level model atmosphere on a simulated planetary boundary layer

A four-level, quasi-geostrophic, ? plane, general circulation numerical model is developed, initially without a simulated boundary layer, and the sensitive dependence of large scale flow characteristics on the numerical choice of essential parameters (non-adiabatic heating funnctions, static stability values, and internal turbulent stresses) is noted in a number of long period (100 day) integrations. It is particularly interesting to note that unless the values of turbulent stress coefficients are sufficiently large, the characteristic structures of cyclone waves and eddy kinetic energy functions are lost and these become random flow patterns and functions. In order to obtain a lower limit estimate of the sensitivity of dependence of large scale flow model characteristics on the presence of a planetary boundary layer, a simple constant ‘height’ (from 1 000 to 900 mb) ‘Ekman boundary layer’ is then introduced, an analytic solution of the linearised boundary layer equations being matched to the numerical model through the vertical velocity field at the model grid points. The effect of this introduction on the structure of the meridional circulation is very marked, and the magnitude of this circulation is seen to depend quite sharply on the numerical value chosen for the model boundary layer eddy viscosity. It is also found that the most realistic large scale flow characteristics are reproduced with a boundary layer present, when the free atmosphere turbulence (vertical) stress coefficients are reduced to quite small values. DOI: 10.1111/j.2153-3490.1975.tb01668.x