Length-scale-dependent stress relief mechanisms in indium at high homologous temperatures

Nanoindentation and electron microscopy have been used to examine the length-scale-dependent stress relaxation mechanisms in well-annealed, high-purity indium at a homologous temperature of 0.69. The experimental methods, analysis, and observations serve as a stepping stone in identifying the stress relaxation mechanisms enabling the formation and growth of metallic dendrites originating at the buried interface between a metallic anode and a solid electrolyte separator. Indium’s load–displacement data are found to be very similar to that of high-purity lithium. Residual hardness impressions show two distinct surface morphologies. Based on these morphologies, the measured hardness, and the estimated pile-up volume, it is proposed that residual impressions exhibiting significant pile-up are the result of deformation dominated by interface diffusion. Alternatively, impressions with no significant pile-up are taken to be the result of shear-driven dislocation glide. An analytical model is presented to rationalize the pile-up profile using interface diffusion

Agronomic and Physiological Characteristics of Forage Sorghum (Sorghum bicolor L.) under Water Deficit Stress and Silicon Fertilizer

IntroductionThe quantity and quality of forage plants are beneficial and useful due to their role in animal husbandry, reproduction and other livestock products. Due to the limitation of water resources, water-deficit as a significant biotic stress is the most severe threat to world food security and is responsible for many yield losses. Plants constantly modify their physiological processes in response to various biotic and abiotic stress to regulate the balance between plant growth and defense response. Many researchers have documented that plant nutrients are involved in biological processes of plants. It has been stated that the use of silicon by increasing the ability to absorb water can be useful to improve drought tolerance of sorghum, sorghum can with the help of silicon extract more water from dry soil and maintain more stomatal conductance.Materials and MethodsIn order to evaluate the effect of silicon fertilizer on the quantitative and qualitative yield of forage sorghum (Sorghum bicolor L.) under water-deficit stress, a split-plot experiment was performed in a randomized complete block design in at the research farm of Varamin, Iran in 2017-2018. The treatments included irrigation in three levels irrigation in field capacity and irrigation at 60% and 45% of field capacity (which were named as full irrigation, moderate and severe water-deficit stress, respectively) as the main plot and silicon fertilizer (Potassium Silicate) in three levels, non-use (control), silicon foliar spraying (three per thousand), and silicon fertigation (10 L ha-1) as the subplot. Silicon spraying with a ratio of three per thousand and silicon irrigation fertilizer at the rate of 10 liters per hectare were considered in three stages.Results and DiscussionThe highest (4.51) and lowest (2.88) leaf area index were achieved in silicon fertigation treatment under full irrigation and none fertilizer treatment and severe water-deficit conditions, respectively. Based on the obtained results, the highest total chlorophyll content (1.73 mg g-1 FW), relative water content of leave (88.08%), stomatal conductance (2.46 cm s-1) were achieved in fertigation treatment under full irrigation conditions. The results show that the amount of electrolyte leakage increased due to water-deficit stress, but silicon fertilizer decreased the adverse effect of stress conditions. The lowest level of electrolyte leakage (341.3 µS cm-1) was obtained from the full irrigation and fertigation treatment. The highest crude protein (11.41%) which was higher than full irrigation condition by 1.39% related to severe water-deficit stress. Water-deficit stress caused the increase of cyanuric acid in shoot and increased the content of cyanuric acid by 41.8% compared to full irrigation conditions. Silicon fertilizer led to a decrease in digestible dry matter under water stress conditions, but on the other hand, it led to an increase in the amount of crude protein and also a decrease in the amount of toxic cyanide acid in the shoot production. The results of this study show that the use of silicon fertilizer in all irrigation regimes increased the auxin content compared to the non-use of silicon fertilizer. The highest content of auxin was achieved in the conditions of full irrigation and fertigation treatment (131.4 nmol g-1 of protein) followed by foliar fertilizer treatment (128.2 nmol g-1 of protein). The highest sorghum dry matter production was obtained from the full irrigation treatment with an average of 23.7 ton ha-1, which was 20 and 54% higher than the treatment of moderate and severe water-deficit treatment, respectively.ConclosionIn general, it can be concluded that silicon fertilizer in the form of foliar spraying should be considered by farmers to maintain the natural growth and development of sorghum plant, especially in areas arid and semi-arid. However, its widespread use in other farm crops needs to be investigated

On the correlation between the stress exponent for creep determined by nanoindentation and the mechanism of action enabling stress relief in indium

Instrumented indentation performed at room temperature with a Berkovich and 10 μm radius sphere has been used to measure the stress exponent for creep before and after the strain burst observed in well-annealed, high-purity indium. Before the strain burst, the measured values are successfully rationalized using a new model based on stress directed diffusional flow along the interface between the indenter tip and test specimen. After the strain burst, the measured stress exponents are found to be representative of dislocation glide and climb assisted glide. These results are compared and contrasted to the previous experimental investigations and modeling efforts of Feng et al., Lucas et al., and Li et al. Collectively, the experimental observations and rationalization presented here provide significant new insight into the mechanisms of action that control the competition for stress relief in small, constrained volumes of crystalline metals subjected to high homologous temperatures. Graphical abstract: [Figure not available: see fulltext.

Diagnostic reference levels and median doses for common clinical indications of CT: findings from an international registry

OB JECTIVES: The European Society of Radiology identified 10 common indications for computed tomography (CT) as part of the European Study on Clinical Diagnostic Reference Levels (DRLs, EUCLID), to help standardize radiation doses. The objective of this study is to generate DRLs and median doses for these indications using data from the UCSF CT International Dose Registry. METHODS: Standardized data on 3.7 million CTs in adults were collected between 2016 and 2019 from 161 institutions across seven countries (United States of America (US), Switzerland, Netherlands, Germany, UK, Israel, Japan). DRLs (75th percentile) and median doses for volumetric CT-dose index (CTDI(vol)) and dose-length product (DLP) were assessed for each EUCLID category (chronic sinusitis, stroke, cervical spine trauma, coronary calcium scoring, lung cancer, pulmonary embolism, coronary CT angiography, hepatocellular carcinoma (HCC), colic/abdominal pain, appendicitis), and US radiation doses were compared with European. RESULTS: The number of CT scans within EUCLID categories ranged from 8,933 (HCC) to over 1.2 million (stroke). There was greater variation in dose between categories than within categories (p < .001), and doses were significantly different between categories within anatomic areas. DRLs and median doses were assessed for all categories. DRLs were higher in the US for 9 of the 10 indications (except chronic sinusitis) than in Europe but with a significantly higher sample size in the US. CONCLUSIONS: DRLs for CTDI(vol) and DLP for EUCLID clinical indications from diverse organizations were established and can contribute to dose optimization. These values were usually significantly higher in the US than in Europe. KEY POINTS: • Registry data were used to create benchmarks for 10 common indications for CT identified by the European Society of Radiology. • Observed US radiation doses were higher than European for 9 of 10 indications (except chronic sinusitis). • The presented diagnostic reference levels and median doses highlight potentially unnecessary variation in radiation dose. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00330-021-08266-1

Large variation in radiation dose for routine abdomen CT:reasons for excess and easy tips for reduction

Objective: To characterize the use and impact of radiation dose reduction techniques in actual practice for routine abdomen CT. Methods: We retrospectively analyzed consecutive routine abdomen CT scans in adults from a large dose registry, contributed by 95 hospitals and imaging facilities. Grouping exams into deciles by, first, patient size, and second, size-adjusted dose length product (DLP), we summarized dose and technical parameters and estimated which parameters contributed most to between-protocols dose variation. Lastly, we modeled the total population dose if all protocols with mean size-adjusted DLP above 433 or 645 mGy-cm were reduced to these thresholds. Results: A total of 748,846 CTs were performed using 1033 unique protocols. When sorted by patient size, patients with larger abdominal diameters had increased dose and effective mAs (milliampere seconds), even after adjusting for patient size. When sorted by size-adjusted dose, patients in the highest versus the lowest decile in size-adjusted DLP received 6.4 times the average dose (1680 vs 265 mGy-cm) even though diameter was no different (312 vs 309 mm). Effective mAs was 2.1-fold higher, unadjusted CTDIvol 2.9-fold, and phase 2.5-fold for patients in the highest versus lowest size-adjusted DLP decile. There was virtually no change in kV (kilovolt). Automatic exposure control was widely used to modulate mAs, whereas kV modulation was rare. Phase was the strongest driver of between-protocols variation. Broad adoption of optimized protocols could result in total population dose reductions of 18.6–40%. Conclusion: There are large variations in radiation doses for routine abdomen CT unrelated to patient size. Modification of kV and single-phase scanning could result in substantial dose reduction. Clinical relevance: Radiation dose-optimization techniques for routine abdomen CT are routinely under-utilized leading to higher doses than needed. Greater modification of technical parameters and number of phases could result in substantial reduction in radiation exposure to patients. Key Points: • Based on an analysis of 748,846 routine abdomen CT scans in adults, radiation doses varied tremendously across patients of the same size and optimization techniques were routinely under-utilized. • The difference in observed dose was due to variation in technical parameters and phase count. Automatic exposure control was commonly used to modify effective mAs, whereas kV was rarely adjusted for patient size. Routine abdomen CT should be performed using a single phase, yet multi-phase was common. • kV modulation by patient size and restriction to a single phase for routine abdomen indications could result in substantial reduction in radiation doses using well-established dose optimization approaches