BACKGROUND:There are numerous studies about mechanical changes of recast cobalt-chromium ceramic al oys. However, little is reported on the mechanical properties of cobalt-chromium ceramic al oys containing once-used al oys after recasts.
OBJECTIVE:To study the effects of different proportion of once-used al oys to recasting cobalt-chromium al oys on their mechanical properties, including tensile strength, yield strength, elongation and hardness.
METHODS:Cobalt-chromium al oys cast samples were prepared and recast for three times (40%once-used al oys were added per time). The tensile strength, 0.2%yield strength, percentage of elongation, flexural strength and Vickers hardness of each specimen were measured. In addition, microscopic metal ographic observation was done.
RESULTS AND CONCLUSION:Being recast for three times, cobalt-chromiun al oys showed no significant differences on their tensile strength, 0.2%yield strength, percentage of elongation, flexural strength and Vickers hardness. GenerationⅠal oy samples had uniform size, smal diameter and smal carbide size distributing along the grain boundary, mainly exhibiting spherical and irregular wormlike forms. Generations Ⅱ and Ⅲ samples were uniform in shape, but crystal grains were coarsened a little. Carbide from Generation IV samples began to be coarsened, irregular wormlike carbides were increased in amount, and a few of non-metal ic inclusions could be found in grains. Cobalt-chromium al oys can be recast after addition of 40%once-used al oys for three times at least in air environment, without decrease of the mechanical properties.

Child ; Erythroblastosis, Fetal ; therapy ; Humans ; Infant, Newborn ; Male ; Rh Isoimmunization ; immunology

Objective:To evaluate the sensitivity of the ArcCheck dosimetry system in detecting the leaf open time errors during the center and off-center helical tomotheray delivery quality assurance (DQA).Methods:Nine nasopharyngeal carcinoma (NPC) patients were selected in this study. Two DQA plans were created for each patient: the" center" plan was created by moving the image of the ArcCheck phantom to place the high dose region on the phantom center and the " off-center" plan was created by offsetting the phantom and putting several diodes through a higher does region. Leaf open time errors of 2, 4, 6, 8 and 10 ms were introduced to the Sinogram which was modified using Matlab. Each intentional error plan and original (no error) plan for each patient were measured using both " center" and " off-center" DQA methods, the γ analysis was performed to evaluate the DQA results. The different dose and distance error criteria of 3%/3 mm, 3%/2 mm and 2%/2 mm were selected, and different thresholds of 5%, 10% and 15% were selected for γ analysis. The gradient and the minimum detectable error approach were taken to quantitatively analyze the sensitivity. The correlation between different dose distance error criteria and different thresholds was also evaluated by Pearson correlation analysis. Results:The absolute value of γ gradient of the " center" DQA plans were larger than those of the " off-center" plans in all different γ criteria (all P<0.05). The stricter the γ criteria were adopted, the more sensitive DQA results of leaf open time error were obtained. The minimum detectable error was 2 ms in all different γ criteria for the " center" DQA plan. The minimum error detectability of the " off-center" DQA plan was weaker than that of the " center" DQA plan. The γ passing rates of three different dose distance error criteria were significantly strongly correlated for the " center" DQA plan ( R2>0.9). For the " off-center " DQA plan, only the 3%/3 mm and 3%/2 mm criteria were significantly strongly correlated ( R2>0.9). Significant strong correlation was observed in the γ passing rate at different thresholds between the " off-center" and " center" DQA plans. Conclusions:The " center" DQA plan method is more sensitive than the " off-center" DQA plan method in all γ criteria, and the γ passing rates in different γ criteria are strongly correlated for the " center" DQA plan. The " center" DQA plan method is recommended.

Photothermal therapy (PTT) has attracted significant attention due to minimal side effects and high treatment specificity. However, it often requires very high temperature to achieve complete tumor ablation under a single PTT. Such high temperature brings obvious thermal damage and inflammatory response to the body, affecting the therapeutic effect. In recent years, nitric oxide (NO) has been used to significantly inhibit tumor growth and enhance the sensitivity of tumor cells of temperature and drugs, thus enhancing the therapeutic effect. However, compounds as NO donors often have some disadvantages such as poor biocompatibility and untargeted delivery, etc., therefore, this medical application based on NO therapy is limited. In conclusion, the organic combination of NO donors and photothermal agents (PTAs) is expected to overcome the shortcomings of single therapy and achieve the antitumor effect of "1 + 1 > 2". In view of the rapid development of NO combining with PTT in tumor therapy, this review firstly introduces the antitumor mechanisms of different types of NO donors. Then the treatment strategy based on NO combined with PTT is discussed. Finally, the prospects and challenges of this combination therapy strategy in the clinical treatment of cancer are discussed.

Objective To investigate the relationship between the steroid-sensitive nephrotic syndrome(SSNS) and interleukin-18(IL-18) and to approach the inhibitive role of dexamethasone(DEX) on expression of IL-18 of peripheral blood mononuclear cells(PBMC) in children with SSNS in vitro.Methods IL-18 levels of serum, urine and supernatants of PBMC cultured in vitro were measured by enzyme linked immunosorbent assay(ELISA) in 23 children with SSNS who were either before or after treatment. Fifteen age-matched healthy children served as normal control group, and another 18 children with respiratory infections as infectious control group.Results There were signi-ficant differences of IL-18 in serum and urine before and after treatment in children with SSNS (t=15.072,16.149 Pa

Objective To investigate the impact of injection current (IC), injection voltage (IV), and pulse forming network (PFN) on energy (depth ratio D20/D10) and profiles of helical tomotherapy, and to improve the quality control for the stability of beam characteristics.Methods The energy and profiles were measured by ion chamber and TomoDose at different values of IC, IV, and PFN, the relationship between the energy and various parameters was evaluated by Pearson correlation analysis, and the changes in profiles were evaluated by comparative analysis.Results The energy had no correlation with IV and PFN values (P>0.05), but had a strong correlation with IC value (P=0.007), which showed a downward trend with the increase in IC.For the profiles in the x direction:(1) in the main beam region (-200 to 200 mm), the shoulder area of the profiles increased regularly with the increase in IC.There were no significant changes for the profiles when the IV values ranged from 6.42 V to 6.54 V, and the shoulder area of the profiles reached the highest point with IV=6.60 V, then decreased with further increase in IV.The shoulder area of the profiles decreased regularly with the increase in PFN.(2) In the penumbral region (±200 mm outside), all the three parameters had no effect on the profiles.For the profiles in the y direction:(1) in the main beam region (-20 to 20 mm), the profiles showed an upward trend in the area with an off-axis distance less than 16 mm when IC values were 5.40 V and 5.46 V, and showed an upward trend in the area with an off-axis distance less than 16 mm.But on the whole, the shoulder area of the profiles increased with the increase in IC, and was not affected by IV and PFN.(2) In the penumbral region (±20 mm outside), the profiles decreased regularly with the increase in IV, and was not affected by IC and PFN.IC had the highest influence on the profiles in the main beam region, followed by PFN and IV.Only IV had impact on the profiles in the penumbral region.Conclusions When the energy needs to be adjusted, the IC value should be given a priority, and PFN should be taken as a supplementary factor.When the profile needs to be adjusted, the IC value should be given a priority, and IV should be used as an auxiliary factor in the main beam region.But in the penumbral region, adjustment of parameters is only related to the profiles in y direction, so the IV value should be adjusted.This study has a guiding role in the quality control of energy and profiles, which can reduce the blindness of quality control, thus saving the time.

AIM:To evaluate the changes of the corneal surface morphology undergoing overnight orthokeratology treatment and assess the effect of optical center deviation in controlling the development of myopia.METHODS:This was a retrospective clinical study.One hundred and thirty-four children (134 eyes) with myopia aged 10.66 ± 1.79 years were treated with overnight orthokeratology lenses.The examinations of visual acuity,axial length and corneal topography were performed before and 3,6,12,18 and 24mo after wearing orthokeratology.The results of right eye were taken as the object of this study,SPSS19.0 for statistical analysis.RESULTS:The distance of decentration about 134 children at 3,6,12,18 and 24mo after wearing orthokeratology were 0.84±0.45mm,0.77±0.40mm,0.79± 0.41 mm,0.78±0.41 mm,and 0.79±0.42mm respectively.The difference between these groups were not statistically significant (F=1.187,P=0.319).The mean distance of decentration after orthokeratology treatment was 0.79 ± 0.35mm,the growth of axial length after 24mo was 0.32± 0.30mm,the mean distance of decentration divided into 3 groups,mild (＜0.5mm) 27 eyes,medium (0.5-1.0mm)79 eyes,severe (＞ 1.0mm) 28 eyes,the growth of axial length frow 3 groups after 24mo were 0.45±0.34mm,0.32 ±0.28mm,0.23 ± 0.29mm,were statistically significant difference between each groups (F=3.825,P=0.024).By linear-regression analysis,the growth of axial length and the mean distance of decentration after 24mo was statistically significant difference (F =7.246,P =0.008),equation of linear regression was Y=0.478-0.194X.At 24mo after wearing orthokeratology,the mean distance of decentration about 18 eyes with monocular diplopia was 1.18±0.36mm,and 116 eyes without monocular was 0.73± 0.31mm,the distance of decentration were statistically significant difference (t=5.59,P＜0.01).CONCLUSION:The degree of decentration tended to be stable after 3mo of orthokeratology treatment and influenced the effect of myopia control and visual quality.

Biomechanical Phenomena ; Electromyography ; Gait ; Humans ; Lower Extremity ; Muscle, Skeletal ; Walking

OBJECTIVETo observe the effect of synchronous perfusion of specific respiratory chain complex IV inhibitor sodium azide (NaN3) in brain on rat ventromedial prefrontal cortex (mPFC) and acetylcholine (ACh) and choline (Ch) contents in hippocampal extra-cellular fluid, and establish the AD rat model induced by mitochondrial acute injury.

METHODThe synchronous dual-probe dual-channel brain microdialysis sampling technology was applied to synchronously perfuse modified Ringer's solution containing NaN3 (50 micro mol L-1) and neostigmine (2 micro mol L-1) into mPFC and hippocampus of conscious, freely moving normal rats, and continuously collect dialysates from different encephalic areas. Dynamic contents of ACh and Ch were determined by high performance liquid chromatography-post-column immobilized enzyme reactor-electrochemical process.

RESULTACh and Ch contents in mPFC extracellular fluid of normal rats were higher than that in hippocampus. During the process of perfusion, NaN3 could significantly reduce ACh in mPFC/hippocampal extra-cellular fluid, but remarkably increase Ch, and constantly inhibit the recovery of ACh and Ch contents in mPFC/hippocampus.

CONCLUSIONThe synchronous perfusion of NaN3in rat mPFC and hippocampus can injure functions of the cholinergic nerve projection area, and cause the acute AD model with ACh and Ch metabolic disorders. This model can be used in pathogenetic and pharmacological studies.

Acetylcholine ; metabolism ; Animals ; Choline ; metabolism ; Extracellular Fluid ; drug effects ; metabolism ; Hippocampus ; cytology ; Male ; Neurotransmitter Agents ; metabolism ; Perfusion ; Prefrontal Cortex ; cytology ; Rats ; Rats, Sprague-Dawley ; Sodium Azide ; administration & dosage ; pharmacology ; Time Factors

OBJECTIVETo establish a method of TLC identification for Dida commonly used in Tibetan medicine from different species.

METHODWith silica gel G as the stationary phase, and chloroform-methanol (40: 1) as mobile phase, oleanolic acid from different species of Dida was separated and identified.

RESULTOleanolic acid was detected in 70 kinds of Dida derived from the Gentianaceae Swertia, Halenia, Gentianopsis, Lomatogonium, and Saxifragaceae saxifrage, except for the saxifrage, there are some differences among different genera or subjection.

CONCLUSIONThis TLC method can be used for identification of oleanolic acid in Dida from different species except saxifrage.

Chromatography, High Pressure Liquid ; Chromatography, Thin Layer ; methods ; Drugs, Chinese Herbal ; chemistry ; Medicine, Tibetan Traditional ; methods ; Oleanolic Acid ; analysis ; chemistry ; Species Specificity