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1.
IntroductionThe dose creep phenomenon is now a widely recognized concept in diagnostic radiography in light of recent technological advancements transnationally. However, this still remains underexplored amongst radiography students preparing to enter the radiography profession. In response, this study explores the perceptions of dose creep amongst undergraduate student radiographers.MethodsThe methodological approach utilized in this research study was grounded theory. The qualitative approach aimed to uncover findings from a higher education institution in Australia. Six students were recruited and took part in semi-structured interviews. This enabled the exploration of previously uncovered data, leading to the construction of original theory within the clinical and academic environment. The data analysis employed was constant comparative analysis (CCA).ResultsA number of insights emerged from the qualitative data set. For instance, the radiography students understanding of the term ‘dose creep’ and decision making leading to dose creep in the clinical environment is captured. This is further supported with assessment of image evaluation determining appropriate exposure factor selection and future impact upon graduation as diagnostic radiographers. The findings identify some important learning needs and actions for both clinical and academic settings which may help foster good use of X-ray exposures.ConclusionThis paper concludes by affirming some challenges surrounding optimal exposure selection and the known phenomenon, dose creep. Further, this study identifies the importance of learning and teaching in the clinical environment whereby learned behaviour leads to suboptimum practices.Implications for practiceThis study advances the existing evidence base by providing a unique lens into the knowledge and understanding of dose creep amongst radiography students in both academic and clinical contexts. It is anticipated this paper will help practitioners and educators better understand potential instances of dose creep within the clinical environment. 相似文献
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《Burns : journal of the International Society for Burn Injuries》2021,47(8):1844-1850
IntroductionTraditionally, lactated Ringer’s solution (LR) has been utilized for the resuscitation of thermally injured patients via the Parkland or Brooke formulas. Both of these formulas include colloid supplementation after 24 h of resuscitation. Recently, the addition of albumin within the initial resuscitation has been reported to decrease fluid creep and hourly fluids given. Our institution has previously advocated for a crystalloid-driven resuscitation. Given reports of improved outcomes with albumin, we pragmatically adjusted these practices and present our findings for doing so.MethodsOur burn registry, consisting of prospectively collected patient data, was queried for those at least 18 years of age who, between July 2017 and December 2018, sustained a thermal injury and completed a formal resuscitation (24 h). At the attending physician’s discretion, rescue colloid was administered using 25% albumin for those failing to respond to traditional resuscitation (patients with sustained urine output of <0.5 mL/kg over 2–3 h, or unstable vital signs and ongoing fluid administration). We compared the total volume of the crystalloid-only and rescue colloid resuscitation fluids given to patients. We also examined the in/out fluid balances during resuscitation. Statistical analysis was performed using Stata software.ResultsA total of 91 patients with thermal injuries were included: the median age was 40 (IQR 31–57), 73% were male, and 30 patients received rescue albumin. The percentage of total body surface area burned (%TBSA) was greater in those who received rescue albumin (40.3% vs. 34%; p = 0.047). Despite a higher %TBSA in the albumin group, the total LR given during resuscitation was not significantly different between groups (15,914.43 mL vs. 11,828.71 mL; p = 0.129) even when normalized for TBSA and weight (ml LR/kg/%TBSA: 4.31 vs. 3.66; p = 0.129. The average in/out fluid ratio for the rescue group was higher than for the crystalloid group (0.83 ± 0.05 vs. 0.59 ± 0.11; p = 0.06) and returned to normal after colloid administration.ConclusionRescue albumin administration decreases the amount of fluid administered per %TBSA during resuscitation, and also increases end organ function as evidenced by increased urinary output. These effects occurred in patients who sustained larger burns and failed to respond to traditional crystalloid resuscitation. Our findings led us to modify our current protocol and a related prospective study of clinical outcomes. 相似文献
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A concrete-filled steel tube (CFT) combines the advantages of concrete and steel in construction and structural applications. However, research on the time-dependent deformation of the CFT under long-term sustained loading are still limited, particularly for stress transfer between the steel tube and concrete due to creep. This study investigated the creep behavior of CFT over a long period of 400 days. The creep and shrinkage strain of CFT was significantly lower than those of concrete that was not confined within a steel tube. The vertical strains of the steel tube and concrete core were almost identical, and it was shown that they were well bonded and acted as a composite. The vertical stress of steel increased by 32.7%, whereas the vertical stress of concrete decreased by 15.8% at 375 days. The stress transfer is notable and cannot be neglected in CFT design. Moreover, the results of creep and shrinkage were compared to prediction values of the B4 model and B4-TW model to verify their validity. 相似文献
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文题释义:黏弹性力学:连续介质力学的重要分支,又称黏弹性理论,研究黏弹性物质的力学行为、本构关系及其破坏规律,以及黏弹性体在外力和其他因素作用下的变形和应力分布。聚合物、混凝土、金属、岩石、土壤、石油、肌肉、血液和骨骼等,在一定条件下既具有弹性性质又具有黏性性质,这种兼具弹性和黏性性质的材料称为黏弹性材料,含黏弹性固体与黏弹性流体,又可分为线性黏弹性体和非线性黏弹性体。线性黏弹性体的两种极端情况即为胡克体(遵循胡克定律)和牛顿流体(遵循牛顿粘性定律)。
生物力学:是应用力学原理和方法对生物体中的力学问题定量研究的生物物理学分支,其研究范围从生物整体到系统、器官(包括血液、体液、脏器、骨骼等),从鸟飞、鱼游、鞭毛和纤毛运动到植物体液的输运等。 物力学的基础是能量守恒、动量定律、质量守恒三定律并加上描写物性的本构方程。生物力学研究的重点是与生理学、医学有关的力学问题,依研究对象的不同可分为生物流体力学、生物固体力学和运动生物力学等。
背景:以往对改性玻璃离子水门汀的力学性能研究多以压缩、弯曲实验居多,关于玻璃离子水门汀加入锶羟基磷灰石后的应力松弛、蠕变实验研究鲜有报道。
目的:对比分析传统玻璃离子水门汀、复合树脂釉质粘接剂、改性玻璃离子水门汀的应力松弛、蠕变特性。
方法:按质量比15%向玻璃离子水门汀中加入掺锶羟基磷灰石,制备改性玻璃离子水门汀。制作改性玻璃离子水门汀、复合树脂釉质粘接剂与传统玻璃离子水门汀试样,3组各取10个试样进行应力松弛实验,另取10个试样进行蠕变实验。
结果与结论:①应力松弛实验7 200 s时,传统玻璃离子水门汀组应力下降了1.18 MPa,复合树脂釉质粘接剂组应力下降了1.39 MPa,掺锶羟基磷灰石复合玻璃离子水门汀组应力下降了1.38 MPa;传统玻璃离子水门汀组应力下降量小于掺锶羟基磷灰石复合玻璃离子水门汀组、复合树脂釉质粘接剂组(P < 0.05),掺锶羟基磷灰石复合玻璃离子水门汀组和复合树脂釉质粘接剂组应力下降量无差异(P > 0.05)。②蠕变实验7 200 s时,传统玻璃离子水门汀组应变上升了0.24%,复合树脂釉质粘接剂组应变上升了0.33%,掺锶羟基磷灰石复合玻璃离子水门汀组应变上升了0.32%;传统玻璃离子水门汀组应变上升量小于掺锶羟基磷灰石复合玻璃离子水门汀组、复合树脂釉质粘接剂组(P < 0.05),掺锶羟基磷灰石复合玻璃离子水门汀组试和复合树脂釉质粘接剂组应变上升量无差异(P > 0.05)。③结果表明,15%掺锶羟基磷灰石提高和改善了玻璃离子水门汀的黏弹特性,有利于其与黏结物体的黏结,有利于提高黏结强度。
ORCID: 0000-0003-1024-5733(丁洁)
中国组织工程研究杂志出版内容重点:生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程 相似文献
6.
Marco Morreale Antonio Liga Maria Chiara Mistretta Laura Ascione Francesco Paolo La Mantia 《Materials》2015,8(11):7536-7548
The rising concerns in terms of environmental protection and the search for more versatile polymer-based materials have led to an increasing interest in the use of polymer composites filled with natural organic fillers (biodegradable and/or coming from renewable resources) as a replacement for traditional mineral inorganic fillers. At the same time, the recycling of polymers is still of fundamental importance in order to optimize the utilization of available resources, reducing the environmental impact related to the life cycle of polymer-based items. Green composites from biopolymer matrix and wood flour were prepared and the investigation focused on several issues, such as the effect of reprocessing on the matrix properties, wood flour loading effects on virgin and reprocessed biopolymer, and wood flour effects on material reprocessability. Tensile, Dynamic-mechanical thermal (DMTA), differential scanning calorimetry (DSC) and creep tests were performed, pointing out that wood flour leads to an improvement of rigidity and creep resistance in comparison to the pristine polymer, without compromising other properties such as the tensile strength. The biopolymer also showed a good resistance to multiple reprocessing; the latter even allowed for improving some properties of the obtained green composites. 相似文献
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Medical-grade synthetic poly(lactic-co-glycolic acid) polymer can be used as a biomaterial for nerve repair because of its good biocompatibility, biodegradability and adjustable degradation rate. The stress relaxation and creep properties of peripheral nerve can be greatly improved by repair with poly(lactic-co-glycolic acid) tubes. "Fen sciatic nerve specimens were harvested from fresh corpses within 24 hours of death, and were prepared into sciatic nerve injury models by creating a 10 mm defect in each specimen. Defects were repaired by anastomosis with nerve autografts and poly(lactic-co-glycolic acid) tubes. Stress relaxation and creep testing showed that at 7 200 seconds the sciatic nerve anastomosed by poly(lactic-co-glycolic acid) tubes exhibited a greater decrease in stress and increase in strain than those anastomosed by nerve autografts. These findings suggest that poly(lactic-co-glycolic acid) exhibits good viscoelasticity to meet the biomechanical require- ments for a biomaterial used to repair sciatic nerve injury. 相似文献
8.
The transplantation of artificial blood vessels with 〈 6 mm inner diameter as substitutes for human arterioles or veins has not achieved satisfactory results. Umbilical vein has been substituted for ar- tery in vascular transplantation, but it remains unclear whether the stress relaxation and creep be- tween these vessels are consistent. In this study, we used the fetal umbilical vein and middle cere- bral artery from adult male cadavers to make specimens 15 mm in length, 0.196-0.268 mm in tu- nica media thickness, and 2.82-2.96 mm in outer diameter. The results demonstrated that the stress decrease at 7 200 seconds was similar between the middle cerebral artery and fetal umbilical vein specimens, regardless of initial stress of 18.7 kPa or 22.5 kPa. However, the strain increase at 7 200 seconds of fetal umbilical veins was larger than that of middle cerebral arteries. Moreover, the stress relaxation experiment showed that the stress decrease at 7 200 seconds of the fetal umbilical vein and middle cerebral artery specimens under 22.5 kPa initial stress was less than the decrease in these specimens under 18.7 kPa initial stress. These results indicate that the fetal umbilical vein has appropriate stress relaxation and creep properties for transplantation. These properties are advantageous for vascular reconstruction, indicating that the fetal umbilical vein can be transplanted to repair middle cerebral artery injury. 相似文献
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