C.P titanium/Ti-6Al-4V joint by spark plasma welding: Microstructure and mechanical properties.

The welding ability of Ti-6Al-4V alloy is weak due to their two-phase microstructure. On the other hand, friction welding methods lead to significant microstructural changes. In this research, for the first time, pure titanium was successfully joined to the Ti-6Al-4V alloy, without any change in the microstructure and mechanical properties of both alloys, by applying the SPW method. Further, the effects of temperature, pressure, and time of the SPW process on the microstructure and mechanical properties of commercial pure (C.P) titanium joined to the Ti-6Al-4V alloy were investigated. The results indicated that the effect of temperature and pressure on the SPW process was greater than that of time. Further, mechanical properties investigations showed that the yield strength of the joint interface was larger than that of the substrate metal, following which necking and fracture occurred in the pure titanium substrate metal. The alloy (Ti-Ti64) bonded at 800 °C, with a time of 10 min and pressure of 20 MPa, exhibited the superior bonding of 7-9 µm interface thickness, and excellent tensile strength (534 ± 13 MPa) and Vickers micro-hardness (190 ± 5 HV0.1). Investigation of the effect of pressure (normal stress) also showed that with an increase in pressure, because of the reduction of the chemical potential of diffusing species, the joint temperature would drop, and the joint could be created at a temperature below 800 °C.

Spark plasma welding joining of copper- AISI4140 steel: Microstructures and mechanical properties.

The main aim of this research study was to characterize the microstructures and mechanical properties of Cu-AISI4140 steel solid-state joining created via the spark plasma welding (SPW) method with and without using molds. To explore the effect of mold on the joining of copper/steel, the SPW process was done at 650 °C for 30 min under the pressure of 20 MPa, with and without mold. Microstructural evaluations indicated the diffusion-affected zone (DAZ) in the SPW process increased with mold, as compared to the sample considered in the absence of the mold process. Also, the SPW process with the mold, in response to the lack of the formation of the oxide layer and dead zone, was affected by the process pressure, in comparison to that without the mold process, leading to the reduction of unjointed areas and the formation of micropores constrained at the joining interface; as such, the joining strength was increased from 42 MPa to 90 MPa. The elevation of the applied pressure from 20 MPa to 40 MPa at 650 °C resulted in enhancement of the joining strength up to 106 MPa, but it had no perceptible effect on raising the strength and diffusion affected zone (DAZ) of the joint.

Fuzzy-based models' performance on qualitative and quantitative land suitability evaluation for cotton cultivation in Sarayan County, South Khorasan Province, Iran.

Using appropriate models in the land use planning process will help increase the accuracy and precision of decisions made by designers. The aim of this study was to investigate and compare fuzzy-based models (fuzzy set theory, fuzzy-AHP, and fuzzy-ANP) to evaluate the suitability of cotton cultivation in Sarayan region (located in eastern Iran). Twenty-eight land units were selected. Weighted arithmetic means of characteristics were performed in representative soil profiles of each unit. Landform-related characteristics were directly entered into the land suitability evaluation modeling. The land index was calculated using three selective qualitative land suitability model guidelines. Qualitative and quantitative land suitability was estimated. The validity of models was determined by r2, RMSE, GMER, and MAPE indicators between predicted and actual production. Soil texture, pH, calcium carbonate equivalent, drainage, organic matter, salinity and sodicity, slope, and gypsum are the most important, respectively. Also, the fuzzy-ANP method is more efficient than other models due to its higher r2 (0.98) and lower RMSE (4.31) and MAPE (0.56) and GMER (0.99) closer to 1. The value of cotton production using fuzzy, fuzzy-AHP, and fuzzy-ANP methods was calculated as 1085 to 4235, 1235 to 4318, and 1391 to 4452 tons per hectare, respectively. The high efficiency of the fuzzy-ANP model is due to the characteristics of the lands used in the evaluation process that are not independent of each other and this model considers them. Examining these models in different weather conditions and combining with the other computational intelligence methods in future experiments are recommended.

Ammonium metavanadate (NH4VO3): a highly efficient and eco-friendly catalyst for one-pot synthesis of pyridines and 1,4-dihydropyridines.

In this study, we reported the ammonium metavanadate (NH4VO3) as an efficient, cost-effective, and mild catalyst for the synthesis of substituted pyridines via a one-pot pseudo four-component reaction. Furthermore, we investigated Hantzsch 1,4-dihydropyridines (1,4-DHPs) synthesis and oxidation of 1,4-DHPs to their corresponding pyridines. The present approach offers a rapid methodology for accessing various pyridines with broad functional group tolerance and good yields using NH4VO3 catalyst as a green catalyst.

The effect of cryoprecipitate on prevention of intra cerebral hemorrhage and brain contusion expansion in traumatic patients.

BACKGROUND: Traumatic brain injury (TBI) is a general and socioeconomic complication and is one of the important causes of mortality and disability among young people in the world. Falling and violence and sports injuries are the other cause. It causes for about ten million new patients, accounting for 9% of all deaths. This interventional study aims to investigate the effects of early administration of cryoprecipitate to prevent expansion of intracranial hemorrhage. METHODS: This randomized clinical trial recruited 54 non-pregnant patients. 27 patients in the control group and 27patients in the interventional group. For all patients, common and accepted procedures in scientific centers, including anticonvulsant drugs, normal saline and the other routine management was done and only for patients in the intervention group, 4 units of cryoprecipitate were added to their routine treatments; computed tomography scan (CT) scan was performed 48 hours later in both groups and finally the contusion size was compared in both groups. RESULTS: It was observed in the intervention group that by adding 4 units of cryoprecipitate to their treatments; they had no increased size of the brain parenchymal contusion according to the criteria defined in the study compared to the control group (OR: 0.08, 95% CI: 0.0102_0.6303). CONCLUSIONS: According to a clinical trial, it seems that cryoprecipitate can prevent of cerebral parenchymal hemorrhage expansion in traumatic patients.

Disability-Adjusted Life Years and Mortality Rate Attributed to Brain and Central Nervous System Cancer in the Middle East and North Africa Countries.

BACKGROUND: Primary brain tumors are among the main causes of death. This study aimed to determine the epidemiological features of the brain and central nervous system cancer in the Middle East and North Africa (MENA) region. METHODS: In this study, data of the Global Burden of Disease (GBD) study were used to estimate the incidence, prevalence, deaths, disability-adjusted life years (DALYs), and mortality in 21 countries in the MENA region from 1990 to 2019 based on age and sex. The percentage of the changes of epidemiologic indicators was calculated between 1990 and 2019. RESULTS: Palestine and Turkey had the highest rate of brain and central nervous system cancer in 2019. Saudi Arabia, Oman, Iraq, and Lebanon had the highest percentage of incidence rate changes from 1990 to 2019. The prevalence of brain and central nervous system cancer in the MENA region was increased from 7.51 (95% CI: 4.95-11.01) in 1990 to 16.45 (95% CI: 10.83-19.54) in 2019 (percentage of changes = 54.35%). The standardized age mortality rate in the MENA region was increased by 2.7% in 2019 compared to that in 1990. The rate of standardized age of DALY per 100,000 individuals in the MENA region decreased from 135.09 (95% CI: 92.57-199.92) in 1990 to 128.34 (95% CI: 87.81-151.3) in 2019. CONCLUSION: The incidence rate, prevalence, and standardized age mortality (per 100,000) had increased significantly in the MENA region in 2019 compared to those in 1990. Focusing on the diversity of the estimates of such indices in different countries of MENA can lead to the identification of important risk factors for brain cancer in future studies.

The need to increase patient awareness of radiation exposure in imaging modalities: A study on the awareness and attitude of patients.

BACKGROUND: A decline in requests for unnecessary imaging can be achieved through increased patient awareness about imaging modalities and can thus reduce radiation exposure. This study aimed to evaluate patient awareness and attitude about radiation exposure in various imaging modalities. METHODS: This cross-sectional study was performed on 900 patients and used a 12-item questionnaire, of which 824 were fulfilled and analyzed. Statistical analysis was done using SPSS software version 18. RESULTS: The age of respondents ranged from 18-82; most participants were male (71.5%). The highest patient-estimated radiation exposures were for radiology, CT scans, and mammography. More than 20% of individuals believed that ionizing radiation (IR) is used in MRI, and 60% stated that IR is not used in mammography. Results show a significant statistical difference between attitude and behavior of respondents on the question about knowing who to address questions to in regard to amount of radiation, but they asked the person who is more accessible such as a radiology technologist instead of a medical physicist (P < 0.05). In addition, there was significant statistical difference between question 3 (X-ray is used in which method of radiation?) and question 4 (scoring of radiation exposure in each of the imaging modalities; Score one means no radiation, score has more than one meaning of rays), which indicates accuracy of responses of referees (P <0.05). 73.4% of individuals agree about the importance of reduction of radiation during imaging, and most of the individuals (87%) tended to be aware of radiation exposure in each of imaging modalities. CONCLUSION: Given the low patient awareness about imaging modalities and radiation dose, it is recommended to prepare brochures and guidance about radiation exposure and absorbed doses in each modality, to be provided and displayed in imaging clinics.

On the Evidence of Thermodynamic Self-Organization during Fatigue: A Review.

In this review paper, the evidence and application of thermodynamic self-organization are reviewed for metals typically with single crystals subjected to cyclic loading. The theory of self-organization in thermodynamic processes far from equilibrium is a cutting-edge theme for the development of a new generation of materials. It could be interpreted as the formation of globally coherent patterns, configurations and orderliness through local interactivities by "cascade evolution of dissipative structures". Non-equilibrium thermodynamics, entropy, and dissipative structures connected to self-organization phenomenon (patterning, orderliness) are briefly discussed. Some example evidences are reviewed in detail to show how thermodynamics self-organization can emerge from a non-equilibrium process; fatigue. Evidences including dislocation density evolution, stored energy, temperature, and acoustic signals can be considered as the signature of self-organization. Most of the attention is given to relate an analogy between persistent slip bands (PSBs) and self-organization in metals with single crystals. Some aspects of the stability of dislocations during fatigue of single crystals are discussed using the formulation of excess entropy generation.

Epidemiological pattern of pediatric trauma in COVID-19 outbreak: Data from a tertiary trauma center in Iran.

INTRODUCTION: In Iran, like most other countries, COVID-19 has had a deep impact on children's lives. Our hypothesis was that, a significant change in the number of pediatric injuries has happened in trauma centers. In the current study, we intend to identify the possible epidemiological shift in pediatric fracture patterns, by comparing the data from 'COVID-19 era' and the mean data from the past 2 years. To the best of our knowledge there are only few reports on epidemiology of pediatric fractures during the COVID-19 outbreak. METHODS: Data are reported in two sections. In the descriptive section, epidemiological data regarding pediatric fractures referred to Taleghani tertiary trauma center, including demographics, distribution curves, etiologies and fracture types are presented during the 'COVID era', from 1 March 2020 to 15 April 2020. In the comparative section, the aforementioned data are compared with mean data from the past 2 years, the 'non-COVID era'. RESULTS: Altogether 117 of the 288 trauma children (40.62%) had a fractured bone (145 fractures). Patients were mostly boys, with a mean age of 9.87 years (SD=5.27). The three most common fracture types in children included distal radius, mid-forearm and humeral supracondylar fractures. Compared to non-COVID era, the number of pediatric trauma admissions dropped from 589 to 288. No significant change happened in the mean age, male/female ratio and percentage of motor vehicle accidents. Proportion of proximal humeral, proximal forearm, carpal, and hand fractures declined. The number of open fractures significantly dropped (from 12 to 2). CONCLUSIONS: In Iran, overall trend of pediatric trauma has been decreasing during the outbreak; but the lack of reduction in proportion of accidents may pose an alarm that an effective lock-down has not been imposed. This study has implications as to preparing appropriate resources particular to common "COVID era fractures".