Electrochemical micromachining: An Introduction

Copyright © 2016 The Author(s). Electrochemical machining (ECM) is a relatively new technique, only being introduced as a commercial technique within the last 70 years (1). A lot of research was conducted in the 1960s and 1970s but research on electrical discharge machining (EDM) around the same time slowed ECM research (2). The main influence for the development of ECM came from the aerospace industry where very hard alloys were required to be machined without leaving a defective layer in order to produce a component which would behave reliably (3). ECM was primarily used for the production of gas turbine blades (2) or to machine materials into complex shapes that would be difficult to machine using conventional machining methods (4). Tool wear is high and the metal removal rate is slow when machining hard materials with conventional machining methods such as milling. This increases the cost of the machining process overall and this method creates a defective layer on the machined surface (3). Whereas with ECM there is virtually no tool wear even when machining hard materials and it does not leave a defective layer on the machined surface. This paper reviews the application of electrochemical machining with regards to micro-manufacturing and present state of the art micro ECM considering different machined materials, electrolytes and conditions used.The research reported in this article was supported by the European Commission within the project ‘Minimizing Defects in Micro-Manufacturing Applications (MIDEMMA)’ (FP7-2011-NMP-ICT-FoF-285614)

KDM5B Is Essential for the Hyperactivation of PI3K/AKT Signaling in Prostate Tumorigenesis

KDM5B (lysine[K]-specific demethylase 5B) is frequently upregulated in various human cancers including prostate cancer. KDM5B controls H3K4me3/2 levels and regulates gene transcription and cell differentiation, yet the contributions of KDM5B to prostate cancer tumorigenesis remain unknown. In this study, we investigated the functional role of KDM5B in epigenetic dysregulation and prostate cancer progression in cultured cells and in mouse models of prostate epithelium–specific mutant Pten/Kdm5b. Kdm5b deficiency resulted in a significant delay in the onset of prostate cancer in Pten-null mice, whereas Kdm5b loss alone caused no morphologic abnormalities in mouse prostates. At 6 months of age, the prostate weight of Pten/Kdm5b mice was reduced by up to 70% compared with that of Pten mice. Pathologic analysis revealed Pten/Kdm5b mice displayed mild morphologic changes with hyperplasia in prostates, whereas age-matched Pten littermates developed high-grade prostatic intraepithelial neoplasia and prostate cancer. Mechanistically, KDM5B governed PI3K/AKT signaling in prostate cancer in vitro and in vivo. KDM5B directly bound the PIK3CA promoter, and KDM5B knockout resulted in a significant reduction of P110α and PIP3 levels and subsequent decrease in proliferation of human prostate cancer cells. Conversely, KDM5B overexpression resulted in increased PI3K/AKT signaling. Loss of Kdm5b abrogated the hyperactivation of AKT signaling by decreasing P110α/P85 levels in Pten/Kdm5b mice. Taken together, our findings reveal that KDM5B acts as a key regulator of PI3K/AKT signaling; they also support the concept that targeting KDM5B is a novel and effective therapeutic strategy against prostate cancer

Global burden of 288 causes of death and life expectancy decomposition in 204 countries and territories and 811 subnational locations, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021

BACKGROUND Regular, detailed reporting on population health by underlying cause of death is fundamental for public health decision making. Cause-specific estimates of mortality and the subsequent effects on life expectancy worldwide are valuable metrics to gauge progress in reducing mortality rates. These estimates are particularly important following large-scale mortality spikes, such as the COVID-19 pandemic. When systematically analysed, mortality rates and life expectancy allow comparisons of the consequences of causes of death globally and over time, providing a nuanced understanding of the effect of these causes on global populations. METHODS The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 cause-of-death analysis estimated mortality and years of life lost (YLLs) from 288 causes of death by age-sex-location-year in 204 countries and territories and 811 subnational locations for each year from 1990 until 2021. The analysis used 56 604 data sources, including data from vital registration and verbal autopsy as well as surveys, censuses, surveillance systems, and cancer registries, among others. As with previous GBD rounds, cause-specific death rates for most causes were estimated using the Cause of Death Ensemble model-a modelling tool developed for GBD to assess the out-of-sample predictive validity of different statistical models and covariate permutations and combine those results to produce cause-specific mortality estimates-with alternative strategies adapted to model causes with insufficient data, substantial changes in reporting over the study period, or unusual epidemiology. YLLs were computed as the product of the number of deaths for each cause-age-sex-location-year and the standard life expectancy at each age. As part of the modelling process, uncertainty intervals (UIs) were generated using the 2·5th and 97·5th percentiles from a 1000-draw distribution for each metric. We decomposed life expectancy by cause of death, location, and year to show cause-specific effects on life expectancy from 1990 to 2021. We also used the coefficient of variation and the fraction of population affected by 90% of deaths to highlight concentrations of mortality. Findings are reported in counts and age-standardised rates. Methodological improvements for cause-of-death estimates in GBD 2021 include the expansion of under-5-years age group to include four new age groups, enhanced methods to account for stochastic variation of sparse data, and the inclusion of COVID-19 and other pandemic-related mortality-which includes excess mortality associated with the pandemic, excluding COVID-19, lower respiratory infections, measles, malaria, and pertussis. For this analysis, 199 new country-years of vital registration cause-of-death data, 5 country-years of surveillance data, 21 country-years of verbal autopsy data, and 94 country-years of other data types were added to those used in previous GBD rounds. FINDINGS The leading causes of age-standardised deaths globally were the same in 2019 as they were in 1990; in descending order, these were, ischaemic heart disease, stroke, chronic obstructive pulmonary disease, and lower respiratory infections. In 2021, however, COVID-19 replaced stroke as the second-leading age-standardised cause of death, with 94·0 deaths (95% UI 89·2-100·0) per 100 000 population. The COVID-19 pandemic shifted the rankings of the leading five causes, lowering stroke to the third-leading and chronic obstructive pulmonary disease to the fourth-leading position. In 2021, the highest age-standardised death rates from COVID-19 occurred in sub-Saharan Africa (271·0 deaths [250·1-290·7] per 100 000 population) and Latin America and the Caribbean (195·4 deaths [182·1-211·4] per 100 000 population). The lowest age-standardised death rates from COVID-19 were in the high-income super-region (48·1 deaths [47·4-48·8] per 100 000 population) and southeast Asia, east Asia, and Oceania (23·2 deaths [16·3-37·2] per 100 000 population). Globally, life expectancy steadily improved between 1990 and 2019 for 18 of the 22 investigated causes. Decomposition of global and regional life expectancy showed the positive effect that reductions in deaths from enteric infections, lower respiratory infections, stroke, and neonatal deaths, among others have contributed to improved survival over the study period. However, a net reduction of 1·6 years occurred in global life expectancy between 2019 and 2021, primarily due to increased death rates from COVID-19 and other pandemic-related mortality. Life expectancy was highly variable between super-regions over the study period, with southeast Asia, east Asia, and Oceania gaining 8·3 years (6·7-9·9) overall, while having the smallest reduction in life expectancy due to COVID-19 (0·4 years). The largest reduction in life expectancy due to COVID-19 occurred in Latin America and the Caribbean (3·6 years). Additionally, 53 of the 288 causes of death were highly concentrated in locations with less than 50% of the global population as of 2021, and these causes of death became progressively more concentrated since 1990, when only 44 causes showed this pattern. The concentration phenomenon is discussed heuristically with respect to enteric and lower respiratory infections, malaria, HIV/AIDS, neonatal disorders, tuberculosis, and measles. INTERPRETATION Long-standing gains in life expectancy and reductions in many of the leading causes of death have been disrupted by the COVID-19 pandemic, the adverse effects of which were spread unevenly among populations. Despite the pandemic, there has been continued progress in combatting several notable causes of death, leading to improved global life expectancy over the study period. Each of the seven GBD super-regions showed an overall improvement from 1990 and 2021, obscuring the negative effect in the years of the pandemic. Additionally, our findings regarding regional variation in causes of death driving increases in life expectancy hold clear policy utility. Analyses of shifting mortality trends reveal that several causes, once widespread globally, are now increasingly concentrated geographically. These changes in mortality concentration, alongside further investigation of changing risks, interventions, and relevant policy, present an important opportunity to deepen our understanding of mortality-reduction strategies. Examining patterns in mortality concentration might reveal areas where successful public health interventions have been implemented. Translating these successes to locations where certain causes of death remain entrenched can inform policies that work to improve life expectancy for people everywhere. FUNDING Bill & Melinda Gates Foundation

Optimization of process parameters on machining rate and overcut in electrochemical micromachining using grey relational analysis

36-42This paper investigates the effect and parametric optimization of process parameters for Electrochemical micromachining (EMM) of 304 stainless steel using grey relation analysis. Experiments were conducted using machining voltage, pulse on-time, electrolyte concentration and tool tip shapes as typical process parameters. The grey relational analysis was adopted to obtain grey relational grade for EMM process with multiple characteristics namely machining rate and overcut. Analysis of variance was performed to get the contribution of each parameter on the performance characteristics and it was observed that electrolyte concentration and tool tip shape were the most significant process parameters that affect the EMM robustness. The experimental results reveal that, the conical with rounded electrode, machining voltage of 9V, pulse on-time of 15ms and electrolyte concentration of 0.35mole/l is the optimum combination for higher machining rate and lesser overcut. The experimental results for the optimal setting show that there is considerable improvement in the process

Advanced Manufacturing Techniques for Engineering and Engineered Materials

As technology develops, it is extremely important to be aware of the latest developments made in the field of mechanical engineering and materials sciences. It is necessary to carefully study such production trends as 3D printing, casting, welding, surface modification, computer numerical control (CNC), non-traditional ergonomics of Industry 4.0 and hybrid processing methods in order to use these important resources for the benefit of society. Advanced manufacturing technologies for mechanical engineering and engineering materials provide a unified and complete overview of the latest and emerging trends, developments and related technologies with the possibility of commercialization of technologies specific to the production of materials. This book also discusses various methods of machining hard-to-process materials and new materials, including matrix composites. Covering topics such as agricultural waste, traditional mechanical processing and the performance characteristics of materials, this book is an impИспользуемые программы Adobe AcrobatПо мере развития технологий крайне важно быть в курсе новейших разработок, сделанных в области машиностроения и наук о материалах. Необходимо внимательно изучить такие тенденции в производстве, как 3D-печать, литье, сварка, модификация поверхности, компьютерное числовое управление (ЧПУ), нетрадиционная эргономика индустрии 4.0 и гибридные методы обработки, чтобы использовать эти важные ресурсы на благо общества. Передовые технологии производства для машиностроения и инженерных материалов предоставляют единый и полный обзор последних и появляющихся тенденций, разработок и связанных с ними технологий с возможностью коммерциализации технологий, специфичных для производства материалов. В этой книге также рассматриваются различные методы механической обработки труднообрабатываемых материалов и новых материалов, включая матричные композиты. Охватывающая такие темы, как агроотходы, традиционная механическая обработка и эксплуатационные характеристики материалов, эта книга является важным источником информации для и

PERFORMANCE ANALYSIS OF EDM ON GREY CAST IRON USING RSM AND TOPSIS METHOD

Electro discharge machining (EDM) process is applied to machine hard and difficult to cut materials. In this research hard material namely, grey cast iron is used as a workpiece and copper electrode 2 mm in diameter is used for making holes through EDM process. The effect of input parameters such as pulse-on time (Ton), pulse off time (Toff), gap voltage (Vg) and current (I) on material removal rate (MRR) and tool wear rate (TWR) were studied. Based on Response Surface Methodology (RSM) analysis the gap voltage and pulse on time has significant impact on MRR and TWR respectively. The mathematical model is developed for MRR and TWR using RSM. Analysis of variance (ANOVA) shows that voltage has notable impact on MRR. Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) is used to estimate the best combination for higher MRR and lower TWR. Based on the analysis the estimated combination is pulse-on time of 45 μs, pulse-off time of 3 μs, gap voltage of 25 V and current of 10 A

Comparison of Electrochemical Micromachining Performance using TOPSIS, VIKOR and GRA for Magnetic field and UV rays heated Electrolyte

The application of micro components in various fields such as biomedical, medical, automobile, electronics, automobile and aviation significantly improved. To manufacture the micro components, different techniques exist in the non-traditional machining process. In those techniques, electrochemical micromachining (ECMM) exhibits a unique machining nature, such as no tool wear, non-contact machining process, residual stress, and heat-affected zone. Hence, in this study, micro holes were fabricated on the copper work material. The sodium nitrate (NaNO₃) electrolyte is considered for the experiments. During the experiments, magnetic fields strength along with UV rays are applied to the electrolyte. The L₁₈ orthogonal array (OA) experimental design is planned with electrolyte concentration (EC), machining voltage (MV), duty cycle (DC) and electrolyte temperature (ET). The optimization techniques such as similarity to ideal solution (TOPSIS), VlseKriterijumska Optimizacija I Kompromisno Resenje (VIKOR) and grey relational analysis (GRA) were employed to find the optimal parameter combinations. The entropy weight method is used to assess the weight of responses such as MR and OC. The optimal combination using TOPSIS, VIKOR and GRA methods shows the same results for the experimental runs 8, 9 and 7, and the best optimal parameter combination is 28 g/l EC, 11 V MV, 85 % DC and 37°C ET. Based on the analysis of variance (ANOVA) results, electrolyte concentration plays a significant role by contributing 86 % to machining performance. The second and least contributions are DC (3.86 %) and ET (1.74 %) respectively on the performance. Furthermore, scanning electron microscope (SEM) images analyses are carried out to understand the effect of magnetic field and heated electrolyte on the work material

A novel approach for the production and characterisation of aluminium–alumina hybrid metal matrix composites

In this study, aluminium–alumina hybrid metal matrix composites were developed using stir–squeeze casting with ultrasonic stirring. Scrap aluminium alloy wheels (SAAWs) were used as the matrix material, with 1, 2, and 3 wt% of nanosized alumina ((Al _2 O _3 ) _n ) particles as well as 4, 5.5, and 7 wt% of microsized alumina ((Al _2 O _3 ) _m ) particles as reinforcement components. An experimental study was conducted using the Taguchi method with an L9 orthogonal array, and the multiobjective optimisation based on ratio analysis technique was used for optimisation. The effects of different ratios of nanosized and microsized alumina particles as well as ultrasonic parameters, namely amplitude and pulse time, on the microstructure and mechanical properties were evaluated and compared. Pin-on-disc wear tests were conducted in the dry condition under uniform load to determine the influence of nanosized and microsized alumina on the wear behaviour. The results revealed that SAAWs reinforced with 1 wt% of nanosized alumina particles and 5.5 wt% of microsized alumina particles and having an amplitude of 100% and pulse on-time of 180 s exhibited lower porosity and metal loss (wear) as well as higher hardness, tensile strength, and compressive strength than other composites

Electrochemical Micromachining of Stainless Steel with Acidified Sodium Nitrate Electrolyte

AbstractThis paper describes Electrochemical Micromachining (EMM) of stainless steel with acidified sodium nitrate. The sulphuric acid of 0.05m/L is added to the standard electrolyte namely sodium nitrate to solubilise the by-products. The foremost characteristics of EMM are researched through scheme of experiments involving various parameters, such as machining voltage, pulse on time and electrolyte concentration. The performance of acidified sodium nitrate and sodium nitrate on EMM are compared. Based on the study, the machining rate and overcut are significantly improved using acidified sodium nitrate as an electrolyte

Experimental Investigation of Natural Convective Heat Transfer Around Micro-fin Arrays

501-505In recent years development of high speed computers leads to production of IC’s with high performance which leads to more heat generation. With the available space and power, micro-scale natural convection plays a significant role in heat removal mechanism. Researchers worldwide extensively reported the natural convection in macro fin array and analyses on natural convection in micro fin array is not much well researched. This study experimentally investigates the effects of micro fin height and spacing on heat transfer coefficient of heat sink when operating under steady state natural convection conditions. The three different materials such as copper, aluminium and stainless steel were considered and micro fin array are fabricated on it through Wire Electro Discharge Machining (WEDM).Micro fin array with height of 0.25 mm and fin spacing ranging from 1.25 to 2.25 mm are fabricated on the test pieces. The study reveals that micro fin made up of copper shows the highest value for convective heat transfer co-efficient of 11.3 Wm-2K-1 for fin height of 0.25 mm and fin spacing of 2.25 mm