Thickness Reduction Rate Research Articles

Numerical Simulation Study of Wall Thickness Change Rule of Single Point Progressive Molding of Al5083

With the development and progress of science and technology, the application of single-point progressive molding is more and more extensive, but single-point progressive molding still exists the problem of excessive thinning of wall thickness of molded parts, which seriously affects the quality of molded parts. The article takes Al5083 plate forming cone as the research object, uses Abaqus finite element simulation software, according to the principle of single variable, respectively explores the influence of process parameters such as tool head diameter, layer spacing, feed rate and residual height on the average wall thickness reduction rate and the maximum wall thickness reduction rate of the molded parts. The results show that: increasing the tool head diameter, the average wall thickness reduction rate increases and the maximum wall thickness reduction rate decreases; the average wall thickness reduction rate and the maximum wall thickness reduction rate increase with the increase of ply spacing; the average wall thickness reduction rate and the maximum wall thickness reduction rate increase with the increase of the tool feed rate; the average wall thickness reduction rate decreases and the maximum wall thickness reduction rate increases with the increase of the residual height.

A new spinning-extrusion forming technology for the inner-ribbed component

To solve the problem that the rib filling height is low in the traditional spinning forming (TSF) of ribbed component, a new spinning-extrusion forming technology (SEF) was proposed. A convenient device was built to conduct the SEF experiment, whose results show that the new SEF can greatly increase the rib filling height by 53% compared with the TSF. Moreover, the improvement mechanism and prediction model of rib filling height in the SEF were investigated. It is found that the rib filling in SEF is mainly dependent on two deformation stages: tension-shear deformation, which makes the material accumulate and bulge above the rib groove; compression-shear deformation, which makes the accumulated material fill into the rib groove. The final rib filling height is linear dependent on the material bulge amount in the tension-shear deformation stage. And, the improvement of rib filling by SEF lies in it can enhance the duration and deformation amount of tension-shear deformation stage, thus improve the material bulge amount in contrast to the TSF. On these bases, taking the material bulge region in SEF as object, slab method was used to analyze its deformation mechanics and establish the differential mechanical equilibrium equations; Thamasett method was adapted to calculate the spinning force; synthetically, the material bulge amount was theoretically calculated. Then, combing the linear relation between the material bulge amount and rib filling height, the model for prediction of rib filling height in the SEF was developed. The predicted rib filling heights under various processing parameters indicate that the rib filling height can be improved by increasing the extrusion force, thickness reduction rate, feed ratio and roller attack angle in the SEF.

Myopia and Rate of Peripapillary Retinal Nerve Fiber Layer Thickness in Diabetic Patients Without Retinopathy: A 2-Year Longitudinal Study

Purpose The aim of this study was to investigate the association between myopia and longitudinal changes in peripapillary retinal nerve fiber layer (pRNFL) thickness in type 2 diabetic patients without diabetic retinopathy (DR). Methods A total of 1069 participants with a median follow-up time of 1.9 years were included in this study. The participants were categorized into four groups based on the presence of myopia (≤ –0.5 diopter [D]) and diabetes without DR, including a control group (n = 412), diabetes group (n = 416), myopia group (n = 115), and diabetes + myopia group (n = 126). Peripapillary average and sectoral RNFL measurements were obtained using 6 × 6 mm swept-source optical coherence tomography (SS-OCT) scans centered at the optic disc. The change rate of pRNFL, adjusted for age and sex, was calculated and compared among the four groups to investigate the impact of myopia and diabetes. Results The baseline estimated pRNFL thickness after adjustment for covariates was 113.7 μm, 116.2 μm, 108.0 μm, and 105.6 μm in the control, diabetes, myopia, and diabetes + myopia group, respectively (diabetes > control > myopia = diabetes + myopia, p < 0.001). The respective average pRNFL loss in the four groups was –0.48 μm/year, –1.11 μm/year, –1.23 μm/year, and -2.62 μm/year (all p < 0.01). The diabetes + myopia group exhibited a greater rate of average pRNFL reduction compared to the other groups (all p < 0.001). Multivariate analysis using a linear mixed-effects model showed that age, diabetes, axial length (AL), and baseline pRNFL thickness were significantly associated with the rate of average pRNFL reduction. Conclusions The diabetes group showed a faster rate of average pRNFL thickness reduction compared to healthy controls, regardless of the presence of myopia. The average pRNFL thickness decreased more rapidly when diabetes and myopia were present simultaneously than in the individual diabetes or myopia group. Both diabetes and myopia were associated with accelerated pRNFL loss.

Factors influencing the reduction in quadriceps muscle thickness in the paretic limbs of patients with acute stroke

Background & AimsMuscle atrophy is an early event that occurs after stroke, but there are few reports on the changes in skeletal muscle thickness in acute stroke. This study aimed at investigating the factors contributing to reduced muscle thickness in patients with acute stroke. MethodsIn total, 51 patients with stroke and NIHSS >3 were included in our study. They were admitted to our hospital between July 2017 and May 2020.The quadriceps muscle thickness was measured with an ultrasound device on admission and 14 days later.The collected data included age, sex, BMI, disease type, NIHSS, and Japan Coma Scale on admission, hematoma removal, recombinant tissue plasminogen activator, endovascular thrombectomy, neuromuscular electrical stimulation, comorbidities, C-reactive protein and serum albumin levels on admission, start date of enteral nutrition, start date of oral intake, start date of weaning, start date of ambulation, and number of physiotherapy and occupational therapy units. These data were retrospectively retrieved from medical documents. Energy intake, protein intake, and energy adequacy were calculated by a dietician. Multiple regression analysis was used to identify the factors associated with reduced quadriceps muscle thickness. The independent variables were NIHSS, start date of enteral therapy, start date of oral intake, start date of mobilization, and start date of ambulation. ResultsThe rate of change in quadriceps muscle thickness of the paretic limb was -15.3% (interquartile range, -46.1–14.8%). Multiple regression analysis showed that the factors responsible for the decrease in muscle thickness on the paretic side were the start date of oral intake (β: -0.437; 95% Cl, -11.82 to -3.547) and the start date of ambulation (β: -0.342; 95% Cl, -2.405 to -0.445), with a multiple correlation coefficient of 0.615. ConclusionThe date of initiation of oral intake and the date of initiation of ambulation after acute stroke were related to the rate of reduction in muscle thickness on the paretic side. Thus, starting oral intake and ambulation training as early as possible could be important to prevent muscle atrophy. Furthermore, acquisition of swallowing ability and active ambulation training are effective in maintaining muscle mass in acute stroke.

Ductility evaluation for small plate specimens by fracture surface shape change

In this study, tensile tests were conducted on small plate specimens of varying thicknesses to assess the impact of specimen geometry on ductility evaluation. The findings revealed that both fracture elongation and reduction in fracture surface area decreased as plate thickness diminished. Finite element analysis indicated that stress triaxiality at the center of the specimen increased with decreasing plate thickness, contributing to a reduction in fracture strain. Examination of the fracture surfaces showed that the rate of thickness reduction due to deformation was higher for thinner plates. For small plate specimens with a thickness of t=0.75 (SS-J3), the reduction rate of the fracture surface in the width direction was only marginally less than that of the round bar, and the modes of deformation and fracture closely resembled those of the round-bar. Therefore, in SS-J3 specimens, deformation of the fracture surface in the width direction may serve as a reliable indicator for ductility evaluation.

Physicochemical properties of flowable composites using isobornyl methacrylate as diluent monomer.

this study sought to evaluate the effect of isobornyl methacrylate (IBOMA) as a diluent monomer on the physicochemical properties of experimental flowable resin composites. the organic resin matrix of a modal flowable resin composite was formulated with 50 wt.% of bisphenol-A-glycidyl methacrylate (Bis-GMA) and 50 wt.% of a diluent monomer, in which IBOMA was used as a combining or substituent diluent monomer to triethylene glycol dimethacrylate (TEGDMA). The resin matrices were filled with 55 wt.% particles, of which 10 wt.% was 0.05-μm fumed silica, and 45 wt.% was 0.7-μm BaBSiO2 glass. Polymerization shrinkage stress (PSS; n=10), degree of conversion (DC; n=3), maximum rate of polymerization (Rpmax; n=3), film thickness (FT; n=10), sorption (Wsp; n=10), solubility (Wsl; n=10), flexural strength (FS; n=10), flexural modulus (FM; n=10), Knoop microhardness (KH; n=10), and microhardness reduction after chemical softening (HR; n=10) were evaluated. Data were analyzed using one-way ANOVA, followed by Tukey's test (α=0.05; β=0.2). the results showed that the substitution or addition of IBOMA reduced FT (p=0.001), PSS (p=0.013), Rpmax (p=0.001), DC (p=0.001), FM (p=0.006) Wsp (p=0.032), and Wsl (p=0.021). However, when used as a complete substituent, IBOMA demonstrated significantly lower FS (p=0.017) and KH (p=0.008), while TEGDMA demonstrated significantly lower HR (p=0.022). the flowable composite containing IBOMA combined with TEGDMA showed no effect in KH and FS and effectively reduced the PSS, RP, FT, Wsp, and Wsl. However, it showed a reduction in DC, FS, and an increase in HR.

Breaking through the bending limit of Al-alloy tubes by cryogenic effect controlled mechanical properties and friction behaviours

Aluminium alloy (Al-alloy) tubes, especially large-diameter thin-walled tubes with a tough bending radius, have been widely utilised in different industrial clusters owing to their high strength-to-weight ratio and good corrosion resistance. However, achieving such extreme specifications is challenging because severe and nonuniform bending deformation may cause tension and compression instabilities, such as overthinning, cracking, and wrinkling. Considering possible improvements in mechanical properties and friction behaviours of Al-alloy at cryogenic temperature (CT), the cryogenic bending potential of the 6061-O tubes with an extreme ratio of D/t of 89 (diameter/wall thickness) was explored at different deformation temperatures, including room temperature (RT) 20 °C, −60 °C, −120 °C, and −180 °C. First, the cryogenic mechanical properties and friction behaviour of the tubes were characterised. It was found that the overall mechanical properties of the Al-alloy tube were improved because of sub-grain formation and a more uniform distribution of dislocations at CT. The coefficient of friction between the tube and tooling exhibited a varying degree of reduction owing to the sensitivity of the tubes and the lubricant to CT. Subsequently, an innovative experimental platform for cryogenic bending was designed, and a finite element model of cryogenic bending was established. Third, cryogenic tube bendability and mechanism were explored. It was found that 6061-O tube formability can be effectively improved by cryogenic bending; however, there is no monotonic relationship between the bendability improvement and temperature decrease. The temperature to obtain the best bendability is −60 °C, at which the average wrinkle height is decreased by 81.4 %, and the average wall thickness reduction rate is reduced by 23.8 %. The bending limit represented by the bending radius is reduced from a 3.0D bending radius at RT to 1.0D at −60 °C, which is realised by the different or even opposite effects of the mechanical properties of tubes and the friction coefficient between the multiple contact interfaces on wall thinning and wrinkling.

Numerical Study on Metal Transverse Flow Law and Model of Rolled Strip under Variable Specification in Hot Rolling

The research on metal transverse flow under variable specification is of great significance for shape calculation and control in hot strip rolling. The finite element software ABAQUS 2016 is used to establish the elastic–plastic deformation model of a hot rolled strip to study the metal transverse flow. The edge transverse strain εe and center transverse strain εc are introduced to characterize metal transverse flow and calculate the strip flatness. The effect on εe, εc and the flatness increment of similarity of profile under different widths, thicknesses and reduction rates is simulated and calculated. The results show that the change in similarity of profile has a linear influence on εe and εc. The strip has the ability of flatness self-correction due to the metal transverse flow. The ksc of the strip with B = 700 mm is 0.87, which is significantly greater than the 0.45 ksc value of the strip with B = 2100 mm. Priority can be given to ensure the crown requirements during narrow strip rolling. The ksc of the strip with H = 50 mm is 0.45, which is higher than the 0.22 ksc value of the strip with H = 6 mm, and the ksc of the strip with ε = 50% is 0.52, which is higher than 0.30 ksc value of the strip with ε = 10%. It is more reasonable to adjust the crown to a greater extent in the upstream stand to meet the requirement of both flatness and crown for the large entry thickness reduction rate and self-correction ability. A metal transverse flow prediction model based on the full test simulation results is established, which can meet the requirement of crown setting at the exit of each stand and the rapid calculation of online flatness control, and can further make the crown and flatness reach the target values at the finishing exit.

Effects of layer inhomogeneities on the process of sewage sludge convective drying

Convective sewage sludge drying is often carried out in belt dryers, where the air flow is directed through the layer. In such a configuration, drying air properties, as well as the structure of the layer and its homogeneity are key factors affecting the drying process. In the present work, these factors were investigated using laboratory experiments on relatively large sludge samples with a mass of several kilograms. Drying was performed at relatively low drying air parameters (time-averaged temperatures of 65 to 80 °C and velocities of 0.44 to 0.78 m/s). The inhomogeneity of the sludge layer drying was observed by measuring the layer surface temperature with an IR camera. The reduction in layer thickness during drying was measured using an optical laser-based method. Analysis of the data included regression and fitting of the data to parametric drying curves, with the modified Nadhari drying law providing the best fit. The standard deviation of the layer surface thermograms (S) was used as a parameter that accounted for the layer homogeneity and consequently drying evenness. Higher values of S corresponded to lower drying rates and consequently longer drying times, highlighting the importance of producing layers with a homogenous structure. The measured layer thickness reduction rate indicated the overall drying intensity almost from the beginning of drying. Both the surface temperature unevenness and the layer height reduction measurement methods were demonstrated as viable approaches for real-time monitoring of the drying process with potential for application in real-scale dryers.

Multi-objective optimization of loading path for sheet hydroforming of tank bottom

As a critical component of the propellant tank, the tank bottom is subjected to complex loads such as internal pressure and vibration and has high requirements for structural load-bearing capacity. Hydroforming deep drawing is one of the techniques for the integral forming of the tank bottom. As the tank bottom is a large-size thin-walled structure, defects such as cracks and wrinkles are prone to occur during the hydroforming deep drawing process. Aiming at reducing these defects, the hydraulic pressure loading path and blank holder force loading path of the hydroforming deep drawing process are studied, and a multi-objective optimization method is proposed to improve the surface accuracy and thickness distribution uniformity of the tank bottom. The complex loading path curve optimization problem is transformed into a functional relationship between hydraulic pressure and blank holder force with time. The hydraulic pressure and blank holder force at each time node are used as design variables, and the maximum wall thickness reduction rate, rupture trend factor, wrinkle height, and wrinkle trend factor are used as optimization targets. The radial basis function (RBF) neural network is used to establish the approximate model between the loading path and the optimization target, and the multi-objective particle swarm optimization (MOPSO) algorithm is used to optimize the solution. Taking the hemispherical tank bottom as an example, the optimal hydraulic pressure loading path and blank holder force loading path are obtained, and the quality of the formed part is improved.

An efficient pre-hardened cryogenic forming process for AA7075 aluminum alloy sheets

Currently, due to the requirement of lightweight in the transportation field, the demand for high-strength aluminum alloy is increasing, but it is difficult for the traditional forming processes to balance the three components of formability, strength and efficiency. In order to solve this problem, a novel stamping process for high-strength AA7075 aluminum alloy sheets is proposed, termed Pre-hardened Cryogenic Forming (PCF) process. PCF process is based on the W-temper alloy and to fulfill simultaneously the demands of good cryogenic formability and high post-formed strength through a suitable ratio of microstructure between the solution-treated matrix and the pre-aged second phases, thereby cancelling the additional artificial aging treatment and achieving high-efficiency. The good cryogenic formability is assured by solution-treated matrix, while the initial strength and further artificial age-hardening during paint baking are regulated by means of pre-aged second phases. A critical issue for PCF process is to determine the pre-aging process window, i.e., a suitable combination of pre-aging temperature and time period, because there is a contradiction between the cryogenic formability and post-formed strength under the constraint of high efficiency. The results of tensile tests show that AA7075 aluminum alloy after pre-aging at 120 °C for 1 h (PA-120-1h) can achieve excellent comprehensive mechanical properties of cryogenic plasticity and post-baking strength. Combined with the analysis of micro-experimental results, the optimal pre-aging process window of AA7075 aluminum alloy is to ensure that the volume fraction of fine precipitates is between 2.5 % and 4 %, and the recommended ratio of the fine precipitates (<2 nm/≥2 nm) is about 1.5. The mixed structure of the GP zones and the η′ phases for PA-120-1h alloy is the suitable combination of strengthening precipitates for balancing cryogenic plasticity and post-baking strength. Based on the newly-designed cooling system, stamping tests are conducted on a W-shaped beam component to verify the engineering feasibility. Based on PA-120-1h alloy sheets, the component with improved surface quality can be successfully formed by PCF process. The final post-baking strength exceeds 92 % of the tensile strength of AA7075-T6 alloy without extra heat treatment, and the thickness reduction rate is within 10 %. Regardless of the immersion time of the sheets in liquid nitrogen, the PCF process can be finished within 2 min, greatly improving the forming efficiency.

In vitro study of how the undercut amount on the model labial side affects the reduction rate of laminated mouthguard thickness.

An undercut on the model's labial side affects the mouthguard thickness. The aim of this study was to investigate how the undercut amount on the model's labial side affects the reduction rate of laminated mouthguard thickness. Mouthguards were thermoformed using 3.0-mm-thick ethylene-vinyl-acetate sheets for the first and second laminates and a pressure molding machine. Working models were three hard plaster models trimmed so that the undercut amount on the model's labial side was 0°, 10°, and 20° (U0, U10, and U20). A specialized caliper was used to measure the thickness of the incisal, labial surface, and buccal surface of the first layer and the laminated mouthguards. Thickness reduction rate of the first layer or laminated mouthguard due to the model undercut amount were analyzed using one-way ANOVA. Additionally, in each model, the difference in the thickness reduction rate between the first layer and the laminated mouthguard were analyzed by Student's t-test or Welch's test. Differences in the thickness reduction rate depending on the model's undercut amount showed the same tendency between the first layer and the laminated mouthguard. Significant differences were observed between U0 and U10 as well as U0 and U20 at the incisal edge, and these were observed among all models on the labial and buccal surfaces (p < .01). On the labial surface, the rate of decrease in the laminated mouthguard thickness compared to U0 was approximately 10.4% larger for U10 and approximately 14.9% larger for U20 (p < .01). The thickness reduction rate of the laminated mouthguard was significantly smaller than that of the first layer, which was observed in all models at the incisal edge and in U10 and U20 on the labial surface (p < .01). The presence of a 10° or 20° undercut on the model's labial side increases the thickness reduction rate on the labial side of the laminated mouthguard by approximately 10% or 15%.

Numerical simulation and experimental study on electromagnetic punching-flanging process of 6061 aluminum alloy sheets

In order to shorten flanging process and improve manufacturing efficiency, an electromagnetic punching-flanging (EMPF) process was proposed in this work. The EMPF experiments were performed with 6061 aluminum alloy sheets and an electromagnetic-mechanical-fracture numerical simulation was established. The flange formation mechanism and relationships between die-fitting gaps/flange heights and discharge energies were analyzed. The thickness reductions of flanged parts were measured to characterize the flange forming quality. Results showed that sheet deformations during EMPF process mainly occurred in the flanging stage of sheets, and the relationship between flange heights and discharge energies could be represented by a quadratic function. The appropriate increase of discharge energies could reduce the die-fitting gaps. The die-fitting gap (0.506 mm) was minimum under the discharge energy of 7 kJ, which was an optimum discharge energy in this work. The thickness reduction gradually slowed down from this position to fillet positon. The maximum and average thickness reduction rates relative to sheet thickness were 13.6 % and 8.2 % for optimum discharge energy, respectively. Numerical simulation and experimental investigations illustrated that the electromagnetic punching-flanging process can be used for manufacturing flanged parts with high quality.

Prioritizing model trimming to prevent thinning during mouthguard thermoforming: Influence of increased height associated with an acute model angle.

The shape of the working model is one of the major factors affecting the thickness of thermoformed mouthguards. The aim of this study was to clarify the priority of model trimming to prevent thinning during mouthguard thermoforming. Mouthguards were thermoformed using 4.0 mm thick ethylene-vinyl-acetate sheets and a vacuum forming machine. Working models were trimmed so that the angles of the labial surface to the model base were 100°, 90°, and 80°. The posterior height was unified to 30 mm, and the anterior heights were 30 mm (A100-L), 35 mm (A90-M), and 40 mm (A80-H), respectively. When the sheet temperature reached 100°C, vacuum forming was performed. Six specimens were formed for each condition. Mouthguard thickness (incisal edge, labial surface, cusp, and buccal surface) was measured using a specialized caliper accurate to 0.1 mm. Differences in thickness reduction rate due to model shapes were analyzed by one-way ANOVA and Bonferroni's multiple comparison tests. At the incisal edge, there were no significant differences in the reduction rate of the thickness of the mouthguard according to model shapes. On the labial surface, cusp, and buccal surface, the smaller the model angle, the smaller the reduction rate of thickness, and significant differences were observed between A100-L and A80-H, and A90-M and A80-H. On the labial and buccal surfaces, A80-H was more than 7.1% thicker compared with A100-L and more than 5.6% thicker compared with A90-M, and the thickness reduction rate was reduced when the model was trimmed to an acute angle. At the cusp, A80-H was more than 4.3% thicker than A100-L and A90-M. It is useful to trim the model at an acute angle in order to prevent thinning during mouthguard thermoforming, even if the anterior height of the model is increased.

Regional Variety of Reduction in Retinal Thickness of Diabetic Macular Edema after Anti-VEGF Treatment.

Background and Objectives: The presence of refractory cases resistant to anti-vascular endothelial growth factor (VEGF) therapy for diabetic macular edema (DME) is a problem in clinical practice. This study aimed to explore the less responsive area of optical coherence tomography (OCT) 3D map the characteristics of naïve DME cases after their first anti-VEGF. Materials and Methods: In 46 patients with DME who received an intravitreal injection of anti-VEGF agents, retinal thickness in 100 sections of the macular area was measured by 3D-mapping mode using OCT before and 1 month after injection. The density of the microaneurysm (MA) was calculated using merged images of the OCT map and fluorescein angiography. Results: One month after injection, the central retinal thickness significantly decreased (p < 0.0001). In severe edema (retinal thickness more than 500 µm), the area percentages with a reduction rate of the retinal thickness greater than 30% and less than 5% were 6.4 ± 6.6% and 10.1 ± 4.6%, respectively. The reduction rate of the retinal thickness varied from section to section. The mutual distance between the areas of maximum thickness before and after the injection averaged 1.22 ± 0.62 mm apart. The reduction rate of retinal thickness in the thickest region before injection was significantly higher (p = 0.02), and that in the thickest region after injection was lower (p = 0.001) than in the other regions. MA density in the residual edema was significantly higher than in the edema-absorbed area (p = 0.03). Conclusion: DME has areas that show low response to the reduction in retinal thickness with anti-VEGF therapy. A high density of MA may be associated with this pathogenesis.

Multi-step hydroforming process and wall thickness optimization of 5A02 aluminum alloy five-way tube with different branch diameters

The different branch diameters of five-way tube affect the design of loading internal pressure in the hydroforming process, where the large-diameter branch is broken more easily than the small-diameter one due to the same ultimate stress of tube material in one-step forming method. Therefore, the first four-way and then five-way of multi-step forming (FFTF) method and the first three-way and then five-way of multi-step forming (FTTF) method were proposed to fabricate the 5A02 aluminum alloy five-way tube with two kinds of branch diameters to avoid the burst of large-diameter branch tube. The finite element simulation of five-way tube hydroforming process shows that the height of small-diameter branch tube is lower and serious wrinkles appear at the large-diameter branch tube in the one-step forming and FFTF method. By optimizing the length of punch, a five-way tube with a big branch height and uniform wall thickness was obtained with the FTTF method. The approach of lengthening the punch in the experiment increased the height of formed branch and reduced the wall thickness reduction rate of five-way tube in FTTF method. Overall, the findings mentioned above cannot only offer guide in creating five-way tube with excellent quality, but also be taken as reference to the hydroforming studies on multi-way tube in the future.

In situ microstructural evolution of spruce wood during soda pulping using synchrotron X-ray tomography

Abstract A new laboratory reactor to perform in situ studies of structural changes in wood during soda pulping using synchrotron X-ray tomography is presented. The reactor is of recirculation type to provide stable reaction conditions and mimic the industrial situation. Experiments have been performed using this reactor in situ at a synchrotron microtomography beamline to provide sequences of 3D images from which measurement of wood cell wall thickness have been possible for the first time. The results showed that the cell wall thickness increased significantly in the early stage of pulping (&lt;10 min), which is due to the transportation of cooking chemicals through the tracheids, resin channels and pits into the cell wall, which is swollen with the increased pH. Subsequently, the cell wall thickness reduces over the processing time up to 60 min with a high rate, which is inferred to be due to the dissolution and transport of lignin and hemicellulose from the secondary walls, allowing for better transportation of active chemicals deep through the cell wall layers. After 60 min processing, the cell wall thickness reduction rate reduced, as dissolution of lignin and hemicelluloses from the cell walls ceased, while the remaining dissolution occurs mainly at the middle lamella.

Two-Week Central Macular Thickness Reduction Rate >37% Predicts the Long-Term Efficacy of Anti-vascular Endothelial Growth Factor Treatment for Macular Edema Secondary to Retinal Vein Occlusion.

ObjectiveTo determine if the early response assessments can predict the long-term efficacy of anti-vascular endothelial growth factor (VEGF) treatment for macular edema secondary to retinal vein occlusion (RVO-ME).MethodsA retrospective study of patients with diagnosis of RVO-ME and intravitreal anti-VEGF treatment was conducted. Clinical characteristics including age, gender, disease subtype and disease duration were recorded at baseline. The best corrected visual acuity (BCVA and logMAR), intraocular pressure (IOP), and central macular thickness (CMT) were recorded at baseline, 2 weeks, and every month (months 1–6) after injection. Further, we compared the early response assessments between the cured group (6-month CMT ≤ 250 μm) and the uncured group (6-month CMT > 250 μm).ResultsA total of 164 eyes in 164 patients (77 male and 87 female) were included. At each post-injection time point, both BCVA and CMT are significantly decreased from baseline (all P < 0.001). Spearman’s test showed that 2-week CMT reduction rate after the first injection was negatively correlated with BCVA at 6 months (r = −0.359, P < 0.001). Compared with the uncured group (47 cases), the cured group (117 cases) was younger (59.53 ± 11.68 vs. 65.19 ± 13.10 years old, P < 0.01), had more BRVO patients (76.1% vs. 44.7%, P < 0.01), a shorter disease duration (1.92 ± 2.43 vs. 5.05 ± 4.32 months, P < 0.01), lower baseline CMT (527.09 ± 154.95 vs. 768.96 ± 287.75 μm, P < 0.01), and lower baseline BCVA (0.86 ± 0.44 vs. 1.31 ± 0.51, P < 0.01). At each post-injection time point, the cured group had lower CMT and BCVA values when compared to the uncured group (all P < 0.01), and the 2-week CMT reduction rate was identified as the earliest response time to predict the long-term treatment efficacy. Moreover, ROC curve analysis indicated that a 2-week CMT reduction rate >37% yielded the best cut-off point for predicting the long-term cure of anti-VEGF treatment at 6 months (P < 0.001). Multivariable logistic regression confirmed that the 2-week CMT reduction rate >37% was independently associated with the 6-month cured rate (OR = 9.639, 95% Cl = 1.030–90.227, P = 0.047).ConclusionAge, disease duration, baseline CMT, and baseline BCVA are associated with visual outcomes at 6-month of anti-VEGF treatment for RVO-ME. The “2-week CMT reduction rate >37%” after the first injection is an independent factor to predict better long-term outcomes.

Research on the shielding performance and optimization of new type foam metal matrix composite shielding materials

The research and development of new composite shielding materials is of great practical significance for radiation shielding of reactors. Foam metal is light in weight, and has the characteristics of high specific strength and high specific area. From the structural characteristics of the foam metal, a new type of foam metal matrix composite shielding material can be prepared. The foam metal matrix composite shielding material consists of two parts: metal matrix and filling material. In this paper, there are three kinds of foam metal matrix (RAFM, tungsten and nickel) and eight kinds of filling materials (B4C, three kinds of lead-boron polyethylene compounds, two kinds of borated polyethylene compounds, polyimide resin, air). The shielding effect of the above-mentioned foam metal matrix composite shielding material on neutrons and gamma at different porosities is explored through MCNP simulation, and several high-performing shielding combination schemes are obtained. The neutron transmittance less than 50% and the gamma ray transmittance less than 30% are used as shielding targets. The shielding combination schemes obtained above are applied to the shielding model, and then the minimum thickness of the shielding target can be achieved by simulation. The results show that when the foam metal matrix is tungsten, the filling material is B4C and the porosity is 80%, its thickness of 8.5CM can reach the shielding target, which is the best shielding scheme. Compared with the traditional iron/water mixed shielding, the thickness reduction rate of this solution is 84.45% and the mass reduction rate is 47.53% when the above-mentioned shielding target is reached. In addition, the above optimal scheme is compared with the experimental data of nickel-based foam metal to further illustrate the reliability of the new foam metal matrix composite shielding material.

Effect of operating temperature conditions in 21-year-old insulated pipe for a district heating network

Since the insulated pipe in the district heating network should have a service life of more than 30 years based on EN253, the long-term thermal performance of PU foam is substantially important to guarantee sufficient shear strength. To examine the effect of operating temperature conditions on the degradation of PU foam in 21-year-old insulated pipe, two types of aged pipes were prepared from public office and general residence, since a large fluctuation in temperature profile with low average temperature is noted at the public office, while a small variation in temperature profile and high average temperature is noted at the general residence. The rate of thickness reduction in the cell wall of the aged PU foam is relatively faster at the public office than at the general residence since it underwent large fluctuation in operating temperature despite being exposed to low average temperature. In terms of the shear strength of the aged pipe, it exhibits relatively low shear strength at the public office compared to general residence, which reveals that the temperature fluctuation in the operating condition for the DH network tends to influence the degradation rate of the insulated pipe, substantially, compared to average exposed temperature.