Optimal selection of process parameters to reduce vibration during end milling of Al 356/SiC metal matrix composite

Machining performances are strongly influenced by vibration which occurs due to the dynamic nature of machine toolstructures. A self excited vibration commonly known as chatter is frequent debacle occurs during milling operations whichcause worsening outcomes such as excessive tool wear, poor surface finish and reduced tool life. In this paper an effort hasbeen tried to optimize the machining and geometrical parameters for reduced vibration using Taguchi method with greyrelational analysis during end milling of Al356/SiC metal matrix composites. The twin channel piezoelectric accelerometerhas been used to measure vibration. Acceleration amplitudes at two different positions, one in spindle and another in workpiece holder have been recorded for each experiment. Analyses of variance (ANOVA) have been applied to find theprominent parameters and the optimal parameter combination for best average response and signal to noise (S/N) ratio.Grey relational analysis has been implemented to find the optimal permutation of machining and geometrical parameters byconsidering both responses (acceleration amplitude taken at two different positions) simultaneously. Confirmation testsestablished that the grey-based Taguchi method has been successful in optimizing the process parameter for reducedvibration

Optimal selection of process parameters to reduce vibration during end milling of Al 356/SiC metal matrix composite

590-602Machining performances are strongly influenced by vibration which occurs due to the dynamic nature of machine tool structures. A self excited vibration commonly known as chatter is frequent debacle occurs during milling operations which cause worsening outcomes such as excessive tool wear, poor surface finish and reduced tool life. In this paper an effort has been tried to optimize the machining and geometrical parameters for reduced vibration using Taguchi method with grey relational analysis during end milling of Al356/SiC metal matrix composites. The twin channel piezoelectric accelerometer has been used to measure vibration. Acceleration amplitudes at two different positions, one in spindle and another in work piece holder have been recorded for each experiment. Analyses of variance (ANOVA) have been applied to find the prominent parameters and the optimal parameter combination for best average response and signal to noise (S/N) ratio. Grey relational analysis has been implemented to find the optimal permutation of machining and geometrical parameters by considering both responses (acceleration amplitude taken at two different positions) simultaneously. Confirmation tests established that the grey-based Taguchi method has been successful in optimizing the process parameter for reduced vibration

Pattern of acute kidney injury and its outcome in a tertiary care centre

Background: Acute kidney injury is a multiplex disease with severe morbidity and mortality. The trends of acute kidney injury vary according to the regions and the population under study. The aim of this study is to evaluate the trends of acute kidney injury and its outcome in a tertiary care hospital.Methods: The study was a prospective observational study conducted at a tertiary care hospital in a metropolitan city. A total of 102 patients of acute kidney injury were selected based on the Kidney Disease Improving Global Outcomes guidelines of acute kidney injury. The main trends of acute kidney injury presentation and its outcome were assessed.Results: Of 102 patients admitted, 42 had a sepsis related diagnosis (42.41%), 17 patients (17.16%) had cardiovascular disease related acute kidney injury and 12 patients (12.12%) had developed acute kidney injury due to drugs and poisons. According to RIFLE (risk of renal failure, injury to kidney, failure and loss of function and end-stage kidney disease) category, 43.96% of patients belonged to the risk category and 30.77% to the injury category. Of 34 patients in failure category, 23 recovered and 11 did not recover. Authors compared the trends of acute kidney injury in patients who recovered and who deteriorated. The mean serum creatinine values were 3.42 mg/dl in patients who didn’t recover from acute kidney injury and 2.05 mg/dl in patients who recovered. In patients of the recovered group, the mean urine output value is 783 ml/day; in deterioration group, 445 ml/day.Conclusions: Most common etiologies of acute kidney injury in this study include sepsis, drugs and poisons, cardiovascular diseases and diarrheal diseases in order of occurrence. High serum creatinine at admission and oliguria were the most common factors that contributed to deterioration in acute kidney injury

Serological characteristics of Lewis antibodies and their clinical significance – A case series

Introduction: Lewis antibodies have been thought to play a small role in clinical transfusion practice, but recent reports suggest that they have gained more importance in the context of transfusion and transplantation. Data regarding the prevalence of Lewis antibodies and their clinical significance in the Indian context is very limited. Hence, this study was aimed at analyzing the serological characteristics and clinical significance of Lewis antibodies encountered in our patient and donor populations. Methods: The retrospective data analyzed the records of red cell antibody screening results and the additional serological evaluation performed on the donor and patient samples included in the study. Results: A total of 26 study subjects were noted to have Lewis antibodies (including 6 healthy donors and 20 patients). Of them, 13 individuals had anti-Leb, 10 had anti-Lea and the remaining three had an anti-Lea/Leb mixture. IgG Lewis antibodies were detected in 7 individuals. All cases of IgM Lewis antibodies detected were reacting at 37°C. Two patients were suspected of having hemolytic transfusion reactions due to Lewis antibodies. Antigen-negative cross-match compatible units were provided for transfusion in the recipients. Conclusion: Lewis antibodies of the IgM class reacting at 37°C should be regarded as clinically important. The present study findings urge that the lab personnel look for the thermal amplitude of Lewis antibodies, irrespective of the fact that the antibody class and antigen-negative crossmatch compatible units should be provided to avoid hemolytic transfusion reactions

Kell alloimmunization in pregnancy: Lessons to be learnt

With the introduction of anti-D prophylaxis, the incidence of RhD alloimmunization in pregnancy has been significantly reduced. RhD remains the most common cause of hemolytic disease of fetus and newborn (HDFN). Next to anti-D, anti-K and anti-c have been implicated in severe HDFN. Hereby, we report a case of Kell alloimmunization in pregnancy which is a leading cause of HDFN worldwide. This case highlights the need for tertiary care hospitals to establish a well-defined protocol for the management of Kell alloimmunization in antenatal females. Most commonly, Kell alloimmunization is secondary to previous transfusions, and hence, every attempt should be made for primary prevention, i.e., Rh-Kell-matched transfusions for women of reproductive age group

Utility of dithiothreitol in a case of spontaneous autoagglutination due to mixed autoimmune hemolytic anemia in a child – A rare scenario

Mixed autoimmune hemolytic anemia (AIHA) represents <5% of pediatric AIHA cases. Spontaneous agglutination is known in patients with cold agglutinins reacting at room temperature. They often interfere with serological tests; generally, they can be dispersed by simple warming techniques. Rarely, in severe cases, as seen in the index case, dithiothreitol treatment of the red cells is needed to eliminate autoagglutination

Blocked D in RhD hemolytic disease of fetus and newborn

A 3-day-old term neonate was admitted to our hospital for the evaluation of neonatal jaundice. The neonate was born to an RhD-negative multiparous mother who had never received anti-D prophylaxis. The neonate's direct antiglobulin test was 4+. Blood group was B, and Rh D typing was negative using tube technique and positive (2+) using gel card. The mother had anti-D, and anti-D titers were 1:1024. After heat elution, RhD typing of the neonate was positive using tube (2+) and gel technique (4+). The eluate was shown to have anti-D. As the red cells of the neonate were saturated with maternal anti-D, commercial monoclonal anti-D could not bind to D antigen which resulted in false-negative D typing in the neonate. Such blocking phenomenon is rare. The discrepancy was identified while using two different techniques (tube and gel) which aided in early diagnosis and tailored an appropriate treatment. The neonate improved after the initiation of a combination of intravenous immunoglobulin and phototherapy