A national dosimetry audit for stereotactic ablative radiotherapy in lung

Publication date: Available online 20 January 2017
Source:Radiotherapy and Oncology
Author(s): Gail Distefano, Jonny Lee, Shakardokht Jafari, Clare Gouldstone, Colin Baker, Helen Mayles, Catharine H. Clark
Background and purposeA UK national dosimetry audit was carried out to assess the accuracy of Stereotactic Ablative Body Radiotherapy (SABR) lung treatment delivery.Methods and materialsThis mail-based audit used an anthropomorphic thorax phantom containing nine alanine pellets positioned in the lung region for dosimetry, as well as EBT3 film in the axial plane for isodose comparison. Centres used their local planning protocol/technique, creating 27 SABR plans. A range of delivery techniques including conformal, volumetric modulated arc therapy (VMAT) and Cyberknife (CK) were used with six different calculation algorithms (collapsed cone, superposition, pencil-beam (PB), AAA, Acuros and Monte Carlo).ResultsThe mean difference between measured and calculated dose (excluding PB results) was 0.4±1.4% for alanine and 1.4±3.4% for film. PB differences were −6.1% and −12.9% respectively. The median of the absolute maximum isodose-to-isodose distances was 3mm (−6mm to 7mm) and 5mm (−10mm to +19mm) for the 100% and 50% isodose lines respectively.ConclusionsAlanine and film is an effective combination for verifying dosimetric and geometric accuracy. There were some differences across dose algorithms, and geometric accuracy was better for VMAT and CK compared with conformal techniques. The alanine dosimetry results showed that planned and delivered doses were within ±3.0% for 25/27 SABR plans.



http://ift.tt/2iN2aFD

Treating patients with Dynamic Wave Arc: First clinical experience

Publication date: Available online 20 January 2017
Source:Radiotherapy and Oncology
Author(s): Manuela Burghelea, Dirk Verellen, Jennifer Dhont, Cecilia Hung, Thierry Gevaert, Robbe Van den Begin, Christine Collen, Kenneth Poels, Koen Tournel, Marlies Boussaer, Cyril Jaudet, Truus Reynders, Viorica Simon, Mark de Ridder
Background and purposeDynamic Wave Arc (DWA) is a system-specific noncoplanar arc technique that combines synchronized gantry-ring rotation with D-MLC optimization. This paper presents the clinical workflow, quality assurance program, and reports the geometric and dosimetric results of the first patient cohort treated with DWA.Methods and materialsThe RayStation TPS was clinically integrated on the Vero SBRT platform for DWA treatments. The first 15 patients treated with DWA represent a broad range of treatment sites: breast boost, prostate, lung SBRT and bone metastases, which allowed us to explore the potentials and assess the limitations of the current DWA site-specific template solution. For the DWA verification a variety of QA equipment was used, from 3D diode array to an anthropomorphic end-to-end phantom. The geometric accuracy of each arc was verified with an independent orthogonal fluoroscopy method.ResultsThe average beam-on delivery time was 3min, ranging from 1.22min to 8.82min. All patient QAs passed our institutional clinical criteria of gamma index. For both EBT3 film and Delta4 measurements, DWA planned versus delivered dose distributions presented an average agreement above 97%. An overall mean gantry-ring geometric deviation of −0.03°±0.46° and 0.18°±0.26° was obtained, respectively.ConclusionFor the first time, DWA has been translated into the clinic and used to treat various treatment sides. DWA has been successfully added to the noncoplanar rotational IMRT techniques arsenal, allowing additional flexibility in dose shaping while preserving dosimetrically robust delivery.



http://ift.tt/2kc2wBD

Data on gut metagenomes of the patients with Helicobacter pylori infection before and after the antibiotic therapy

Publication date: April 2017
Source:Data in Brief, Volume 11
Author(s): Oksana E. Glushchenko, Andrei E. Samoilov, Evgenii I. Olekhnovich, Boris A. Kovarsky, Alexander V. Tyakht, Alexander V. Pavlenko, Vlad V. Babenko, Andrei K. Larin, Elena S. Kostryukova, Maja V. Malakhova, Elena N. Ilina, Rustem A. Abdulkhakov, Dilyara I. Safina, Tatiana V. Grigoryeva, Sayar R. Abdulkhakov, Vadim M. Govorun
Antibiotic therapy can lead to the disruption of gut microbiota community with possible negative outcomes for human health. One of the diseases for which the treatment scheme commonly included antibiotic intake is Helicobacter pylori infection. The changes in taxonomic and functional composition of microbiota in patients can be assessed using "shotgun" metagenomic sequencing. Ten stool samples were collected from 4 patients with Helicobacter pylori infection before and directly after the H. pylori eradication course. Additionally, for two of the subjects, the samples were collected 1 month after the end of the treatment. The samples were subject to "shotgun" (whole-genome) metagenomic sequencing using Illumina HiSeq platform. The reads are deposited in the ENA (project ID: PRJEB18265).



http://ift.tt/2jLehT8

Data on the influence of cold isostatic pre-compaction on mechanical properties of polycrystalline nickel sintered using Spark Plasma Sintering

Publication date: April 2017
Source:Data in Brief, Volume 11
Author(s): Guy-Daniel Dutel, Patrick Langlois, David Tingaud, Dominique Vrel, Guy Dirras
Data regarding bulk polycrystalline nickel samples obtained by powder metallurgy using Spark Plasma Sintering (SPS) are presented, with a special emphasis on the influence of a cold isostatic pre-compaction on the resulting morphologies and subsequent mechanical properties. Three types of initial powders are used, nanometric powders, micrometric powders and a mixture of the formers. For each type of powder, the SPS cycle has been optimized for the powders without pre-compaction and the same cycle has been used to also sinter pre-compacted powders.



http://ift.tt/2jZ5U3v

Functional magnetic resonance imaging data of incremental increases in visuo-spatial difficulty in an adult lifespan sample

Publication date: April 2017
Source:Data in Brief, Volume 11
Author(s): Kristen M. Kennedy, Jenny R. Rieck, Maria A. Boylan, Karen M. Rodrigue
These data provide coordinates generated from a large healthy adult lifespan sample undergoing functional Magnetic Resonance Imaging (fMRI) while completing a spatial judgment task with varying levels of difficulty, as well as a control categorical condition. The data presented here include the average blood-oxygen-dependent (BOLD) response to the spatial judgment vs. the control task, as well as the BOLD response to incremental increasing difficulty; see also "Age-related Reduction of BOLD Modulation to Cognitive Difficulty Predicts Poorer Task Accuracy and Poorer Fluid Reasoning Ability" (Rieck et al., 2017) [1].



http://ift.tt/2jLfCtj

Phytosterols isolated from Clinacanthus nutans induce immunosuppressive activity in murine cells

Publication date: March 2017
Source:International Immunopharmacology, Volume 44
Author(s): Cheng-Foh Le, Thina Hareesh Kailaivasan, Sek-Chuen Chow, Zunoliza Abdullah, Sui-Kiong Ling, Chee-Mun Fang
Clinacanthus nutans (Burm. f.) Lindau is a traditional medicinal plant belonging to the Acanthaceae family. Its therapeutic potentials have been increasingly documented particularly the antiviral activity against Herpes Simplex Virus (HSV), anti-cancer, anti-oxidant, anti-inflammatory and immunomodulatory activities. However, majority of these studies used crude or fractionated extracts and not much is known about individual compounds from these extracts and their biological activities. In the present study, we have isolated four compounds (CN1, CN2, CN3 and CN4) from the hexane fractions of C. nutans leaves. Using NMR spectroscopic analysis, these compounds were identified to be shaftoside (CN1), stigmasterol (CN2), β-sitosterol (CN3) and a triterpenoid lupeol (CN4). To determine the immunosuppressive potential of these compounds, their effects on mitogens induced T and B lymphocyte proliferation and the secretion of helper T cell cytokines were examined. Among the four compounds, stigmasterol (CN2) and β-sitosterol (CN3) were shown to readily inhibit T cell proliferation mediated by Concanavalin A (ConA). However, only β-sitosterol (CN3) and not stigmasterol (CN2) blocks the secretion of T helper 2 (Th2) cytokines (IL-4 and IL-10). Both compounds have no effect on the secretion of Th1 cytokines (IL-2 and IFN-γ), suggesting that β-sitosterol treatment selectively suppresses Th2 activity and promotes a Th1 bias. CN3 was also found to significantly reduce the proliferation of both T helper cells (CD4⁺CD25⁺) and cytotoxic T cells (CD8⁺CD25⁺) following T cell activation induced by ConA. These results suggested that phytosterols isolated from C. nutans possess immunomodulatory effects with potential development as immunotherapeutics.



http://ift.tt/2jZ3OAM

The bony anchoring reinforcement system (BARS) for flank hernia repair: a versatile technique

Abstract

Background

Abdominal wall reconstruction, especially when fascial defects occur in the flank region, is a field of high interest given the morbidity of hernias. The flank hernia is a rare and challenging entity requiring adequate overlap and secure fixation for a successful repair.

Methods

This is a retrospective case series study including all patients undergoing flank hernia repair using the bony anchoring reinforcement system (BARS) technique from March 2013 through August 2015. An electronic chart review identified seven patients with flank hernias that underwent the BARS procedure.

Results

Six of the patients followed-up for a full year with one patient dropping out after returning to exercise and indicating high satisfaction with operative outcome. There was one recurrent hernia 29 months later. There were no surgical site or mesh infections.

Conclusions

The BARS technique is a versatile and efficacious open approach for repairing flank hernias. It allows for a large area of overlap and secure fixation to the bony structures in the pelvis.

Level of Evidence: Level V, therapeutic study

http://ift.tt/2jK2vYH

Impact of G protein-coupled receptor heteromers in endocrine systems

Publication date: Available online 20 January 2017
Source:Molecular and Cellular Endocrinology
Author(s): K.C. Jonas, A.C. Hanyaloglu
The fine-tuning of endocrine homeostasis is regulated by dynamic receptor mediated processes. The superfamily of G protein-coupled receptors (GPCRs) have diverse roles in the modulation of all endocrine axes, thus understanding the mechanisms underpinning their functionality is paramount for treatment of endocrinopathies. Evidence over the last 20 years has highlighted homo and heteromerization as a key mode of mediating GPCR functional diversity. This review will discuss the concept of GPCR heteromerization and its relevance to endocrine function, detailing in vitro and in vivo evidence, and exploring current and potential pharmacological strategies for specific targeting of GPCR heteromers in endocrine heath and disease.



http://ift.tt/2iWg2Za

MODIS 3 km and 10 km aerosol optical depth for China: Evaluation and comparison

Publication date: March 2017
Source:Atmospheric Environment, Volume 153
Author(s): Qingqing He, Ming Zhang, Bo Huang, Xuelian Tong
The recently released Moderate Resolution Imaging Spectrometer (MODIS) Collection 6 introduced a fine scale aerosol optical depth (AOD) distribution, the 3 km product, which is expected to perform well in analyzing aerosols and identifying local air pollution, especially in the severely polluted atmosphere of China. However, few detailed evaluations of regional variations have been conducted. In this paper, we evaluate MODIS 3 km and 10 km AOD products for China against ground-based measurements and compare their performance with respect to spatial and temporal variations. The ground validations indicate that the two products are generally correlated well to ground-based observations. Spatially, the 3 km product slightly outperform the 10 km product in well-developed areas of southern China. Temporally, both products perform worse during spring and summer. Atmospheric clouds and underlying surface are two key factors that influence the accuracy and number of retrievals for both products. The comparison analysis reveals the newly introduced AOD product clearly shows good relationships with the coarse resolution retrievals in spatial and temporal variation but significant differences regarding details. The 3 km AOD product provides better aerosol gradients, more retrievals in bare areas of western China and some spikes of diurnal variation in cloudy days. Seasonal comparisons show the 3 km AOD product is higher than the 10 km product in all seasons, especially during spring and summer. Although the 3 km product for China generally performs slightly worse than the 10 km product, the added information of the MODIS 3 km AOD product shows potential for studying local aerosol characterization, and may facilitate studies of air pollution.



http://ift.tt/2iMUt23

Chapter 19 Diamond-Based Radiation Detectors for Applications in Highly Corrosive Solutions and High-Radiation Fields

Publication date: 2017
Source:Materials Under Extreme Conditions
Author(s): D. Jain, J. Nuwad, N. Manoj, V. Sudarsan
Diamond, with its name derived from the Greek word adamas (meaning unconquerable/invincible), is a unique material with potential use in several applications. In nature, it occurs deep down in the Earth's crust in regions of high temperatures and high pressures with limited availability and nonreproducible quality. It is also synthesized industrially using high-temperature, high-pressure methods or chemical vapor deposition (CVD) methods. CVD methods in particular have excellent control over the quality of diamond, and it is possible to synthesize pure/doped diamonds using simple gaseous precursors like H2 and suitable carbon source (CH4, CO2, C2H4, etc.) at low pressures. Both single crystals and polycrystalline diamonds of desired quality can be routinely synthesized. CVD method has therefore brought about a revolution in this field and expanded the development of diamond-based technologies. With its inherent physicochemical properties, diamond is an excellent host matrix for radiation detection purposes. It offers the best performance potential especially under extreme operational conditions such as high temperatures, corrosive environments, intense radiation fields, fast radiation events, etc. CVD diamonds have immense application in this area. The present chapter outlines the potential of CVD diamond as a host matrix for radiation detection under extreme conditions and gives description of diamond-based alpha particle detectors for use in highly corrosive chemical environments, with special reference to estimation of actinides in acidic liquids. Results obtained in our research group on development of such detectors are also summarized. Essential factors that influence performance of diamond-based radiation detectors and possible methods to address them are also detailed.



http://ift.tt/2j6u3GW

Chapter 1 Material Studies at High Pressure

Publication date: 2017
Source:Materials Under Extreme Conditions
Author(s): Surinder M. Sharma, Nandini Garg
Subjecting materials to very high pressures is one of the well-established methods to study condensed matter under extreme conditions. Application of pressure can bring about significant changes in the bonding character and consequently in the structural and physicochemical properties of the materials. High-pressure and high-temperature conditions can help simulate the physical conditions inside the earth, planets, and super-earth, synthesize new materials with exotic properties, etc. Even food preservation and successful preservation of organs for transplant can be carried out by application of pressure. This chapter deals with several aspects of high-pressure science, methods of pressure generation, different diagnostic methods employed for studying high-pressure phenomena, and a few studies elucidating the exciting changes in the materials brought about by its application.



http://ift.tt/2j6mYqa

Selective Unidirectional Horizontal Saccadic Paralysis From Acute Ipsilateral Pontine Stroke: Response.

No abstract available

http://ift.tt/2j5TicI

New Treatments in Neuro-Ophthalmology: The Role for Evidence.

No abstract available

http://ift.tt/2jYo1qB

Validity of the modified Berg Balance Scale in adults with intellectual and visual disabilities

Publication date: March 2017
Source:Research in Developmental Disabilities, Volume 62
Author(s): Annemarie Dijkhuizen, Wim P. Krijnen, Cees P. van der Schans, Aly Waninge
BackgroundA modified version of the Berg Balance Scale (mBBS) was developed for individuals with intellectual and visual disabilities (IVD). However, the concurrent and predictive validity has not yet been determined.AimThe purpose of the current study was to evaluate the concurrent and predictive validity of the mBBS for individuals with IVD.MethodFifty-four individuals with IVD and Gross Motor Functioning Classification System (GMFCS) Levels I and II participated in this study. The mBBS, the Centre of Gravity (COG), the Comfortable Walking Speed (CWS), and the Barthel Index (BI) were assessed during one session in order to determine the concurrent validity. The percentage of explained variance was determined by analyzing the squared multiple correlation between the mBBS and the BI, COG, CWS, GMFCS, and age, gender, level of intellectual disability, presence of epilepsy, level of visual impairment, and presence of hearing impairment. Furthermore, an overview of the degree of dependence between the mBBS, BI, CWS, and COG was obtained by graphic modelling. Predictive validity of mBBS was determined with respect to the number of falling incidents during 26 weeks and evaluated with Zero-inflated regression models using the explanatory variables of mBBS, BI, COG, CWS, and GMFCS.ResultsThe results demonstrated that two significant explanatory variables, the GMFCS Level and the BI, and one non-significant variable, the CWS, explained approximately 60% of the mBBS variance. Graphical modelling revealed that BI was the most important explanatory variable for mBBS moreso than COG and CWS. Zero-inflated regression on the frequency of falling incidents demonstrated that the mBBS was not predictive, however, COG and CWS were.ConclusionsThe results indicated that the concurrent validity as well as the predictive validity of mBBS were low for persons with IVD.



http://ift.tt/2jJAL6M

Predictive value of General Movement Assessment for preterm infants’ development at 2 years − implementation in clinical routine in a non-academic setting

Publication date: March 2017
Source:Research in Developmental Disabilities, Volume 62
Author(s): Freia De Bock, Heike Will, Ulrike Behrenbeck, Marc N. Jarczok, Mijna Hadders-Algra, Heike Philippi
BackgroundGeneral movements (GM) are used in academic settings to predict developmental outcome in infants born preterm. However, little is known about the implementation and predictive value of GM in non-academic settings.AimsThe aim of this study is twofold: To document the implementation of GM assessment (GMA) in a non-academic setting and to assess its predictive value in infants born preterm.Methods and proceduresWe documented the process of implementing GMA in a non-academic outpatient clinic. In addition, we assessed the predictive value of GMA at 1 and 3 months' corrected age for motor and cognitive development at 2 years in 122 children born <33 weeks' gestation. Outcome at two years was based upon the Bayley Scales of Infant Development-II (mental/psychomotor developmental index (MDI, PDI)) and a neurological examination. The infants' odds of atypical outcome (MDI or PDI ≤70 or diagnosis CP) and the predictive accuracy of abnormal GMA were calculated in a clinical routine scenario, which used all available GM information (primarily at 3 months or at 1 month, when 3 months were not available). In addition, separate analysis was undertaken for the samples of GMA at 1 and 3 months.Outcomes and resultsTips to facilitate GMA implementation are described. In our clinical routine scenario, children with definitely abnormal GM were more likely to have an atypical two-year outcome than children with normal GM (OR 13.2 (95% CI 1.56; 112.5); sensitivity 55.6%, specificity 82.1%). Definitely abnormal GM were associated with reduced MDI (−12.0, 95% CI −23.2; −0.87) and identified all children with cerebral palsy (CP) in the sample of GMA at 3 months only.Conclusions and implicationsGMA can be successfully implemented in a non-academic outpatient setting. In our clinical routine scenario, GMA allowed for adequate prediction of neurodevelopment in infants born preterm, thereby allaying concerns about diagnostic accuracy in non-academic settings.



http://ift.tt/2iW4chI

Carnosine modulates glutamine synthetase expression in senescent astrocytes exposed to oxygen-glucose deprivation/recovery

Publication date: Available online 20 January 2017
Source:Brain Research Bulletin
Author(s): Xiaojie Shi, Bingyu Wang, Yuan Liu, Jingjing Zhang, Yuyan Huang, Pei Cao, Yao Shen, Jianxin Lyu
Carnosine is believed to be neuroprotective in cerebral ischemia. However, few reports concern its function on senescent astrocytes during cerebral ischemia. The aim of this study was to investigate the effects of carnosine on cell damage and glutamine synthetase (GS) expression in D-galactose-induced senescent astrocytes exposed to oxygen-glucose deprivation/recovery (OGD/R). The results showed that OGD/R caused massive cell damage and a significant decrease in GS expression both in the young and senescent astrocytes. The GS expression level was partly recovered whereas it continued to decline in the recovery stage in the young and senescent astrocytes, respectively. Decreased GS expression significantly inhibited glutamate uptake and glutamine production and release. Carnosine prevented the cell damage, rescued the expression of GS and reversed the glutamate uptake activity and glutamine production in the senescent astrocytes exposed to OGD/R. The modulatory effect of carnosine on GS expression was partly antagonized by pyrilamine, a selective histamine H1 receptors antagonist, but not bestatin. Bisindolylmaleimide II, a broad-spectrum inhibitor of PKC could also reverse the action of carnosine on GS expression. Thus, histamine H1 receptors and PKC pathway may be involved in the modulatory action of carnosine in GS expression in the senescent astrocytes exposed to OGD/R.



http://ift.tt/2jKPcYD

Improved ethanol recovery through mixed-matrix membrane with hydrophobic MAF-6 as filler

Publication date: 7 May 2017
Source:Separation and Purification Technology, Volume 178
Author(s): Qianqian Li, Long Cheng, Jie Shen, Jiayan Shi, Guining Chen, Jing Zhao, Jingui Duan, Gongping Liu, Wanqin Jin
Increasing the hydrophobicity of membrane was believed as an effective approach to enhance the performance of organophilic pervaporation (PV) membrane. In this work, the superhydrophobic alkyl group modificated metal organic framework (MOF) of RHO-[Zn(eim)2] (MAF-6) was incorporated into polydimethylsiloxane (PDMS) polymer to fabricate mixed matrix membranes (MMMs). The morphologies, physical and chemical properties of as-prepared MAF-6 nanocrystals and membranes were characterized with XRD, FESEM, EDX, QCM, contact angle and nano-scratch tests. The pervaporation experiments of ethanol/water mixture show the simultaneously enhanced flux and separation factor of MMMs compared with PDMS pristine membrane (with the optimal flux of 1200g/m²h¹, and separation factor of 14.9), which stems from the hydrophilicity and high porosity of MAF-6, successfully overcoming the trade-off effect.



http://ift.tt/2iMDVqP

Minerals in thalassaemia major patients: An overview

Publication date: May 2017
Source:Journal of Trace Elements in Medicine and Biology, Volume 41
Author(s): Zeynep Ozturk, Gizem Esra Genc, Saadet Gumuslu
Thalassaemia major (TM) is a hereditary blood disease characterised by reduced or absent production of beta globin chains. Erythrocyte transfusions are given to raise the haemoglobin level in patients with thalassaemia major. However, transfusions have been related to increased risk of iron overload and tissue damage related to excess iron. Both elevated oxidative stress due to iron overload and increased hemolysis lead to over utilisation of minerals required for antioxidant enzymes activities. Iron chelators have been used to prevent iron overload in thalassaemia major patients, but these chelators have the possibility of removing minerals from the body. Thalassaemia patients are more at risk for mineral deficiency because of increased oxidative stress and iron chelation therapies. Growth and maturational delay, cardiomyopathy, endocrinopathies and osteoporosis are the complications of thalassaemia. Minerals may play a particular role to prevent these complications. In the current review, we provide an overview of minerals including zinc (Zn), copper (Cu), selenium (Se), magnesium (Mg) and calcium (Ca) in thalassaemia major patients. We, also, underline that some complications of thalassaemia can be caused by an increased need for minerals or lack of the minerals.



http://ift.tt/2kbzJgC

Additive manufacturing of complex-shaped graded TiC/steel composites

Publication date: 15 March 2017
Source:Materials & Design, Volume 118
Author(s): Asaf Levy, Aslan Miriyev, Amy Elliott, Sudarsanam Suresh Babu, Nachum Frage
Complex-shaped TiCx ceramic preforms with a gradient of carbon content in the titanium carbide phase (x changes from 0.7 to 0.98) were fabricated for the first time by Binder jet 3D printing technology. The complex-shaped preforms were infiltrated with molten carbon steel (0.7wt.% C). Thermodynamic considerations showed that carbon could be transferred from titanium carbide to steel and vice versa according to the initial concentration of carbon (activity) in both phases. After infiltration, solidification and slow cooling, a microstructural gradient was obtained throughout the steel matrix from ferrite, in the region where the steel was in contact with titanium carbide of low carbon content (x=0.7), to pearlite, in the region where the steel underwent interactions with stoichiometric titanium carbide (x=0.98). After annealing at 900°C and quenching in oil, a structural gradient in the steel matrix from ferrite to martensite was obtained, resulting in a hardness gradient of 700–1600HV. The suggested processing approach allows for fabrication of complex-shaped graded composites with the desired property gradient suitable for a wide range of practical applications.

Graphical abstract

http://ift.tt/2kbAhTY

Microstructure evolution and mechanical properties of friction stir welding super-austenitic stainless steel S32654

Publication date: 15 March 2017
Source:Materials & Design, Volume 118
Author(s): Huabing Li, Shouxing Yang, Shucai Zhang, Binbin Zhang, Zhouhua Jiang, Hao Feng, Peide Han, Jizhong Li
Super-austenitic stainless steel S32654 sheets with 2.4mm thickness were successfully welded by friction stir welding (FSW) at the rotational speeds of 300 and 400rpm with a constant traverse speed of 100mm/min using W-Re tool. The sound joints with almost no nitrogen loss were successfully produced. The microstructure evolution was characterized by optical digital microscope (ODM), scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), electron backscatter diffraction (EBSD) and transmission electron spectroscopy (TEM). The results suggest that the grain structure evolution in stir zone (SZ) is dominated by continuous dynamic recrystallization (CDRX). The strain rate plays a dominated effect on obvious grain refinement. The band structures containing W and Re are generated due to the wear between tool probe and steel in SZ. Furthermore, the microhardness measurements and transverse tensile tests indicate that the grain refinement combining with high density dislocations and substructures improves the hardness and strength, but greatly reduces the plastic deformation capacity of joints. The more suitable welding parameters are determined as 300rpm and 100mm/min for this steel.

Graphical abstract

http://ift.tt/2kbNb49