m. rafiei

In this research, the transient liquid phase bonding of St52 carbon steel to WC-Co cermet using a copper interlayer with 50 μm thickness was done. For this purpose, samples were jointed to each other at a constant temperature of 1100 ºC and bonding times of 1, 15, 30, and 45 min. The microstructure of the joints was examined using an optical microscope and scanning electron microscope equipped with energy-dispersive X-ray spectroscopy. XRD analysis was also used to investigate the effect of bonding on the phase changes of the bonding area. Microhardness and tensile shear tests were also conducted to study the mechanical properties of the samples. Microstructural investigations showed the formation of three different zones including isothermal and athermal solidification zones and DAZ in the WC-Co base material side, which determine the characteristics of the samples. The isothermal solidification zone contained a Fe-rich solid solution and the athermal solidification zone contained a Cu-rich solid solution. η phase was not formed in the DAZ of WC-Co cermet at bonding times of 1 and 15 min. This phase was formed in the DAZ of WC-Co cermet by increasing the bonding time to 30 and 45 min. The microhardness studies showed that all samples had the same trend. Maximum microhardness was 1100 HV which was related to WC-Co base cermet and the lowest microhardness was about 220 HV which was related to steel base metal. Also, the maximum tensile-shear strength of the bonded samples was about 180 MPa for a bonded sample at a bonding time of 15 min, which was due to the increase in the volume fraction of iron-rich solid solution, as well as proper microstructural continuity and the presence of an optimal amount of copper-rich phase in the microstructure.

The reprocessing tailings of iron ore processing plants is important from economic (as a secondary source of iron) and environmental points of view. The aim of the present study is to determine the appropriate method for recovery iron from the tailings of Balestan iron ore processing plant (located in the northwest of Iran). For this purpose, after taking samples from the tail piles of this plant, a representative sample was selected, and chemical, mineralogical, size distribution, and bond’s work index analyses were performed on it. The total iron grade in the tailings was measured to be about 10%, of which 8.5% was identified as magnetite mineral (with a degree of liberation less than 40%). The d80 value of the sample was 7 mm, and the bond index was measured as 11.84 (kWh/ton). To determine the appropriate method for iron recovery, pre-processing with magnetic drum, grinding, and Davis tube tests were performed. With the magnetic pre-processing of tailings with a particle size of 0-10 mm, under a field of 2000 G and in a dry method, about 80% of the load entering the drum with a total iron grade of 5% was transferred to the tailings. 20% of the input load with an iron grade of approximately 24% was recovered to the concentrate. In order to remove the gangue minerals and enrich the pre-processed concentrate, stepwise grinding and separation had the best results. Comminution was done in two stages to produce products with smaller dimensions of 250 and 45 microns, respectively. Magnetic separation was also done in three stages with 3000 G, and two stages of separation with 1000 G, which finally resulted in a concentrate with a total iron grade of more than 66% and iron recovery of 44.88%.

The present study aimed to evaluate the materials, methods, and equipment used by general dentists in southeastern Iran for endodontic treatments in 2021.  

In this cross-sectional study, 121 standard questionnaires were distributed among general dentists in Rafsanjan city, Iran. The questionnaire included demographics and questions regarding the type of materials, methods, and equipment selected by general dentists. The collected data were analyzed by SPSS version 22 using the Chi-square test and ANOVA.

The response rate of the participants was 83%(n=100); of which, 55% were females and 45% were males. Only 28% of dentists performed pulp vitality tests, and 46% performed sinus tract tracing in case of infection. Cotton rolls were used by 71% for further isolation, apex locator and radiography were used concurrently to determine the working length by 62%, and canal preparation was done by rotary and manual files by 48%. Rotary M3 and ProTaper files were more commonly used by dentists. Electric rotary handpieces were used for canal instrumentation by 64%, and rotary orifice shapers were more commonly used for canal flaring (61%). The most commonly used obturation method was lateral compaction. Most general dentists used formocresol-impregnated cotton pellets for pulpotomy (43%). Half of the dentists used saline for canal irrigation. Calcium hydroxide was the most commonly used intracanal medicament (87%), and 53% used polymerized sealers.

General dentists evaluated in this study violated some of the standards and need to take more training courses.

By formation of the resistant front in Iraq, Syria and Yemen, and by developing strategic depth of Islamic Revolution, reciprocal actions of enemies have engulfed mentioned countries as well. One of those actions is enjoying the Sunni Muslim’s potentials with Salafi and Vahhabi approach. The topic states that I.R of Iran must take care until not being faced with surprised failure not only in its territory but also in the resistant country. In this article the researchers are following to answer the main question as: Has I.R of Iran been faced with surprised failure in Iraq and collapse of Mosul? If yes, the following subordinate questions are being answered: 1- What where the reasons of Iran’s surprised failure in collapse of Mosul? 2- What are the preventive ways of military-security surprised failure by approach, structural and methodical in the future? The following research has been raised as developing and practical and by merging qualitative and quantitative inputs, as well as 3 open-ended questionnaires and mixed method has been used. The time territory is from resuming Islamic Revolution. To answer the questions, by studying upstream/high level documents, expert interviews and comparison studies 9 components and 60 attributes from surprised failure field have been discovered. By arranging expert meeting and 3 questionnaires all the ideas have received, so that we found the essence of the failure in Mosul was ignorance and treason. Reasons and factors of surprised failure have been studied and analyzed by AHP method. Finally, weaknesses and reasons of surprised failure have structural, methodical and logical approach as course of actions.

Nowadays, aluminum and its alloys have extensive applications in marine and aerospace industrious owing to their excellent properties. Among these alloys, 5xxx series of aluminum alloys have also excellent corrosion resistance, high toughness and strength and also good weldability. Decrease in yield strength and also tensile strength due to the grain growth in the heat affected zone is of the main problems in the welding of these series of Al alloys. In this research work, gas tungsten arc weld joints in two modes i. e. direct current and pulsed current were compared in order to study the effect of this parameter on the microstructure, mechanical properties and corrosion resistance of weld joints. Also, the effect pulsed current parameters such as peak current and basic current were investigated. Microstructural evolutions and fracture surfaces of weld joints were examined by optical microscope and scanning electron microscope, respectively. It was found that the fracture behavior of all joints is in a ductile manner. Also, tensile test and electrochemical polarization were conducted in order to study the mechanical properties and corrosion behavior of weld joints.

In this research, the effect of temperature and time on the properties of AISI420/SAF2507 dissimilar joint produced by transient liquid phase bonding process was investigated. A BNi-2 interlayer with 25 μm thickness was inserted between two dissimilar steel samples. The bonding process was performed at 1050 oC and 1100 oC for different bonding times. The microstructures of the joints were studied using optical microscope, scanning electron microscope and energy dispersive X-ray spectroscopy. Microhardness and tensile shear strength of bonded samples were investigated. Isothermal solidification was completed for the joints bonded at 1050 oC and 1100 oC for 45 min and 30 min, respectively. ASZ and ISZ areas of the bonding zone at the bonding temperature of 1050 oC indicated the highest (520 HV) and the lowest (300 HV) microhardness values, respectively. Sample bonded at 1050 oC for 1 min indicated the lowest tensile strength (196 MPa) and sample bonded at 1100 oC for 60 min indicated the highest tensile strength (517 MPa).

Traumatic pandemics have been repeated periodically in human kind history. Covid 19 or coronavirus is one of the last and most pervasive until yet. Adherence to quarantine and attention to health related protocols are the most effective strategies for prevention from this pandemic and therefore warranting the social health. Therefore the recognition of effective and associated factors in this area is important. The present study was designed to assess quarantine and health related protocols adherence and some related factors.

The present study was conducted by internet questionnaires via social networks on 202 participants during quarantine days in January 2020.In the present study, one researcher made questionnaire and NEO5 personality questionnaire were used to assess aimed factors. Data were analyzed using SPSS.

According to the results of the study, about 67% of people over 75 adhered to the principles of quarantine and 72% adhered to the same guidelines. On the other hand, the results showed that in both fields (adherence to quarantine at the level of 0.06 and observance of instructions 0.001 were significant) women had higher scores than men. Accordingly, the urban population had a higher score than the rural population in the amount of investment to fight the corona and follow the announcement of the trustees. In terms of investment, married people had a higher score (significance 0.04). Regarding age, only the rate of participation in voluntary activities by the group of 20 to 35 years was almost significantly different (0.06). The results correspondingly revealed that the literacy variable in these behaviors, especially the willingness to invest (significant 0.03) and following the instructions of trustees (0.04) had a significant difference which had higher scores in both doctoral and higher literacy. In the field of job variability, the results indicated that the treatment staff reported the highest score in adherence to the principles. In addition, no significant relationship was observed between personality traits and adherence to the two mentioned issues.

This study revealed that the rate of quarantine and observance of hygienic principles was higher than most reports elsewhere. On the other hand, the degree of quarantine adherence and observance of health principles had a significant relationship with the variables of gender, residence, age, occupation, education and marriage and there was no significant relationship in terms of personality traits.

Coronary artery disease (CAD) risk factors are increasing in developing counties.Previous studies have shown a high prevalence of CAD risk factors in Iran but geographical prevalence is not uniform. We performed this study to determine the prevalence of these risk factors in Yazd province, central Iran.

In this cross-sectional study, a total of 2000 participants, 1000 men and 1000 women among Yazd citizens, were surveyed and data was recorded in a 500-item questionnaire.

About 85% of Yazd citizens had at least one and 61.1% had at least two coronary artery disease risk factors. The present study showed that 16.38% of Yazd citizens were obese (9.2% in men and 24.2% in women), and 43.3% of men and 62.05% of women had excess weight.Prevalence of hypercholesterolemia was 12.1% (10.6% in men and 13.8% in women, respectively), dyslipidemia 58.5% (59% and 57.6%, respectively), high blood pressure (HTN) 25.6% (27.5% and 23.5%, respectively), diabetes mellitus (DM) 11% (10.48% and 11.5%, respectively), impaired glucose tolerance 8.5% (7.9% and 9.1%, respectively) and cigarette smoking 13.12% (24.45% and 0.5%, respectively). The prevalence of hypercholesterolemia, dyslipidemia, DM, HTN, and abdominal obesity increased significantly with age (p<0.005).The prevalence of obesity, abdominal obesity, hypercholesterolemia and DM was significantly higher in women.

Excess weight, dyslipidemia and HTN were the most prevalent risk factors in Yazd.Although Yazd did not have the highest levels of risk factors in Iran, but the findings showed that Yazd is one of the “at risk” cities with regard to prevalence of risk factors. Preventive and therapeutic programs should thus be considered as a major health priority in Yazd.

The Clinical and Paraclinical Characteristics of patients with congestive heart failure (CHF) have been described by a number of previous studies, but very little information is available on this issue in Iran. This study aimed to delineate the clinical and paraclinical characteristics of Iranian patients hospitalized with CHF.

During an observational, analytical, descriptive, cross-sectional study, 258 consecutive patients were interviewed and examined at 5 hospitals in Yazd, Iran from January to December 1999.Questionnaire comprised of information regarding etiology, signs, symptoms, paraclinical data, etc. Results were analyzed by SPSS9.01 and EPI6 programs using ANOVA, Chi-Square and T-TEST and reported as Mean ± SD.

The study population had a high mean age (67.59 ± 0.73), 0.8% were less than 35 years old and 70.80% were older than 65 years. Mortality rate due to heart failure was 7.5%. Major causes of CHF were ischemia (65.1%), valvular lesions (5.8%), cardiomyopathy (5%) and hypertensive heart diseases (4.6%). Mean number of hospitalizations per year was 2.2 ± 0.1, while mean hospitalization time was 7.25 ± 3.8 days and mean cost was 1122439 ± 89874.8 rials.

Even though many background and aggravating factors of heart failure are preventable, this disease incurs a lot of expenditure on our country’s health system. Therefore, there is a requirement for programming and research in the fields of education, treatment and prevention of this disease for all members of the community.

The relationship between microalbuminuria and coronary events has been established. In the case of retinopathy; however, the issue is controversial. The aim of this study was to determine the relationship between diabetic retinopathy and myocardial infarction as a major presentation of CAD. 180 diabetic patients with and without myocardial infarction were studied in this analytical case-control study. Each group consisted of 38 females and 52 males with a mean age (SD) of 58.27 (11.38) years in the case group and 56.85 (11.11) years in the control group. The two groups were matched except for history of myocardial infarction. SPSS analysis of the data showed no significant differences between the two groups in terms of age and duration of diabetes (DM) [10.34 (8.17) years in the case vs. 10.54 (8.22) years in control group]. There was a significant relationship between the severity of retinopathy and duration of DM (p=0.05), but no significant relation between sex and retinopathy severity was obtained (p=0.1 in case vs. p=0.3 in control group). Although no significant difference between the two groups in terms of the severity of retinopathy (p=0.5) was detected, in the subgroup of the diabetic patients with MI and less than 5 years' duration of DM, retinopathy was more common (p=0.05). Premature retinopathy can predict coronary events. Immediate CAD screening of all diabetic patients with retinopathy is recommended.

Several studies have evaluated the association of admission blood glucose levels and short and long term mortality after myocardial infarction and have had different results. The aim of this study was evaluation of association between admission blood glucose levels and in-hospital and one year mortality in non-diabetic patients with AMI.

In this study, demographic, clinical and Para clinical data of 120 non-diabetic patients with AMI on admission was collected and analyzed. The patients were followed for one year. Blood glucose level ≥ 140 mg/dl was defined as hyperglycemia.

78% of patients were men. The mean age and admission blood glucose level was 63+13 years and 146+76mg/dl, respectively. Death due to cardio vascular causes was seen in 20% of patients in hospital and 9.8% during the one year follow up. The mean admission blood glucose level in patients who died in hospital was significantly more than live patients and also had an influence on the in-hospital outcome. Every 100mg/dl increase in blood glucose level was associated with 11% increase in in-hospital mortality risk in non-diabetic patients.

Our results demonstrate that admission blood glucose level is a good marker for diagnosing patients with worse prognosis after AMI. We suggest that later studies should focus on optimal control of hyperglycemia with insulin in patients with AMI.

Previous studies have shown that various factors such as emotional stress can trigger of MI in susceptible persons. More studies are needed to evaluate the characteristics of patients regarding to emotional stress, heavy work, routine activity, infection or rest before occurrence of MI.

We studied 608 consecutive hospitalized in CCUs from May 2000 to October 2001. For patients, questionnaires including demographic, clinical and paraclinical characteristics were completed and data analyzed.

In this study rest (33.4%) and ordinary activity (32.4%) were more prevalent among the MI situations and infection had the lowest prevalence (0.7%). In patients higher than 45 years we had similar results, but in age group younger than 45 year ordinary activity (30.6%) and after heavy work (20.8%) had the highest prevalence before occurring of MI. In Diabetic patients, MI developed in sleep situation more frequently.(17.8%),(P=0.03) 52.5% of MI mortality occurred in rest situation.(P=0.009)

Rest had the highest prevalence of MI compared to other situations but in age group younger than 45 years MI after heavy work had the highest prevalence. Autonomic neuropathy may be one of the reason of higher prevalence of MI in sleep situation.

Everyday, millions of people around the world go through phlebotomy, either to donate blood or for therapeutic intention. The most important worrisome adverse effects are hemodynamic alterations. In this study, hemodynamic changes following blood donation were assessed. Methods & Materials: Three hundred laborers who donated blood voluntarily were enrolled in this study. Blood pressure (BP) and pulse rate were measured before the procedure, ten minutes afterwards, and one week following phlebotomy. Hemoglobin (Hgb) and hematocrit (Hct) were also determined prior to and one week after phlebotomy. Finally, results before and after donation were compared with each other.

242 volunteers had normal BP and 58 were hypertensive. The mean systolic blood pressures (SBP) before phlebotomy, ten minutes after the procedure, and one week later were 120, 117, and 122 mmHg, respectively. During the same periods of time, the mean of diastolic blood pressures (DBP) were 77 , 78 and 78 mmHg , in order , while pulse rates on average were 80 , 82 and 76 beats/minute . None of the aforementioned changes were clinically significant. After one week, Hgb decreased by about 0.3 g/dl (P<0.001) and Hct declined on average of 1.7 (P<0.001). Forty six individuals had high DBP and one week after donation, their DBP was reduced by 7 mmHg. Age, body mass index and smoking did not have any significant effect on hemodynamic status.

Hemodynamic changes in healthy blood donors were not clinically significant. It seems that DBP drops desirably in hypertensive individuals. This needs to be evaluated more carefully in future studies.

Background:

Cardiovascular diseases are the main cause of death in diabetic patients. ‎Various studies have shown simultaneous involvement of coronary artery disease ‎along with peripheral artery diseases (PAD).‎ ‎‎ The aim of this study is to evaluate the ability of Ankle/Brachial Index (ABI) to ‎foretell the possibility of ischemic heart diseases in diabetic patients‎ ‏.‏

Methods: 

The diabetic patients, who visited our diabetes research center between May ‎‎2000 and May 2001 and were, confirmed diabetics for the previous 2 or more years, ‎were enrolled in the study. The ABI was calculated for all of the patients and their Demographic specifications and ischemic heart disease risk factors were recorded. All ‎the patients referred to perform an exercise test according to the Bruce protocol. ‎

Results: 

Four hundred ninety- seven patients (52.4%) were women, and 451 patients ‎‎(47.6%) were men. The mean age was 55.25 ± 10.08 years. 10.2%of the patients had ‎an ABI <_ 1. ABI showed a significant reduction in patients > 60 years (P = 0.02). ‎Two hundred thirty- eight patients were in group I (25.1 %), 625 patients in group II ‎‎(65.9 %) and 85 patients in group III (9%). 52.8% of the 125 patients in Group I, ‎‎19.6% of the 107 patients in group II and 44.7% of the 47 patients in Group III had ‎positive exercise test. I, II (P=~ 0.00) - II, III (P = 0.05).A total of 108 patients out of ‎the 279 patients had positive exercise test (38%) and most of them were from groups I ‎&III. 72.2% of group I and 52.5% of group II had high blood pressure (P - 0.00‎‏(.‏

‎‎ Conclusion: 

Ankle Brachial Index (ABI) with cutoff point 51.1 & >_ 1.4 is an ‎independent predictor of coronary artery diseases in diabetic patients, especially in ‎those who are hypertensive (Iranian Heart Journal 2002, 2003; 3(4) & 4(1): 47-55‎‏).