Role of Threaded Tool Pin Profile and Rotational Speed on Generation of Defect Free Friction Stir AA 2014 Aluminium Alloy Welds

Influence of threads on tool pin and rotational speeds on defect occurrence in friction stir welding (FSW) of aluminum alloy AA 2014 T6 plates has been studied. The effect of FSW forces on the evolution of mechanistic defects, caused in turn through a variation in heat generation during the process has also been examined. In case of conical tool pin, relatively lower rotational speeds resulted in unbounded zones and micro defects while high speeds caused excessive flash, thereby resulting in surface defects and voids inside the weld. The FSW joints were defect-free at moderate speeds, hinting an optimum heat generation and flow. Reaction forces on the tool pin, in the welding direction, were correlated with the defect formation. Tools equipped with a threaded conical pin profile resulted in sound welds, irrespective of the tool rotational speeds in the entire range of 400 rpm - 2400 rpm. The threaded conical pin, with a relatively larger frictional area, may be contributing to higher levels of heat generation compared to a plain conical pin. Further, positive displacement of the hot plasticised material by the threads will carry away excess heat from the advancing-to-the-retracting side and simultaneously downwards, thus confining all heat within the weld zone.

Bioconversion of glycerol waste to ethanol by Escherichia coli and optimisation of process parameters

Biofuel is one of the best ways to reduce our dependence on fossil fuels. Ever since commercial biodiesel production began, waste glycerol, the biodiesel byproduct, has gained researchers’ interest, especially its recycling. Here, we explored using glycerol residue (carbon source) as a substrate in the fermentation process for ethanol production by Escherichia coli K12 in anaerobic conditions. The factors affecting the ethanol production was optimised by response surface methodology (RSM). Significant variables that impact the ethanol concentration were pH, temperature and the substrate, with a statistically significant effect (P <0.05) on ethanol formation. The significant factor was analyzed by the Box-Behnken design. The optimum conditions for bioethanol formation using glycerol as substrate was obtained at pH 7 and temperature 37°C. The ethanol productivity was 0.77 g/L/h. The ethanol concentration of 9.2 g/L achieved from glycerol residue was close to the theoretical value with the fermentation achieved at optimised terms

Bioconversion of glycerol waste to ethanol by Escherichia coli and optimisation of process parameters

Biofuel is one of the best ways to reduce our dependence on fossil fuels. Ever since commercial biodiesel production began, waste glycerol, the biodiesel byproduct, has gained researchers’ interest, especially its recycling. Here, we explored using glycerol residue (carbon source) as a substrate in the fermentation process for ethanol production by Escherichia coli K12 in anaerobic conditions. The factors affecting the ethanol production was optimised by response surface methodology (RSM). Significant variables that impact the ethanol concentration were pH, temperature and the substrate, with a statistically significant effect (P &lt;0.05) on ethanol formation. The significant factor was analyzed by the Box-Behnken design. The optimum conditions for bioethanol formation using glycerol as substrate was obtained at pH 7 and temperature 37°C. The ethanol productivity was 0.77 g/L/h. The ethanol concentration of 9.2 g/L achieved from glycerol residue was close to the theoretical value with the fermentation achieved at optimised terms

Bioconversion of Glycerol into Biofuels—Opportunities and Challenges

Rising pollutants and greenhouse gas emissions from fossil fuels are serious environmental concerns that led to a tremendous focus of scientific research. The use of renewable resources as feedstock to produce fuels could help preserve the environment and offer economic and social sustainability. This preceded the development of alternative fuels such as biodiesel, and bioethanol. Over the last decade, the substantial expansion of biodiesel production indicates stoichiometrically increased crude glycerol co-production. Due to the surplus availability of the crude glycerol (as it does not find any potential application for complete utilisation), its market value has fallen and is even seen as a waste stream instead of a lucrative co-product. While high-purity glycerol is used in cosmetics, food, paints, and pharmaceutical industries for medicines, crude glycerol is an attractive organic carbon substrate to produce value-added products through microbial fermentation or physicochemical processing. The review discussed the recent developments in glycerol to produce fuels such as bioethanol, hydrogen, and methanol. Besides, it highlights the opportunities and challenges in utilising crude/waste glycerol generated from the biodiesel industry

Evolution of electrospinning in liver tissue engineering

The major goal of liver tissue engineering is to reproduce the phenotype and functions of liver cells, especially primary hepatocytes ex vivo. Several strategies have been explored in the recent past for culturing the liver cells in the most apt environment using biological scaffolds supporting hepatocyte growth and differentiation. Nanofibrous scaffolds have been widely used in the field of tissue engineering for their increased surface-to-volume ratio and increased porosity, and their close resemblance with the native tissue extracellular matrix (ECM) environment. Electrospinning is one of the most preferred techniques to produce nanofiber scaffolds. In the current review, we have discussed the various technical aspects of electrospinning that have been employed for scaffold development for different types of liver cells. We have highlighted the use of synthetic and natural electrospun polymers along with liver ECM in the fabrication of these scaffolds. We have also described novel strategies that include modifications, such as galactosylation, matrix protein incorporation, etc., in the electrospun scaffolds that have evolved to support the long-term growth and viability of the primary hepatocytes

Biomaterial strategies for alleviation of myocardial infarction

World Health Organization estimated that heart failure initiated by coronary artery disease and myocardial infarction (MI) leads to 29 per cent of deaths worldwide. Heart failure is one of the leading causes of death in industrialized countries and is expected to become a global epidemic within the twenty-first century. MI, the main cause of heart failure, leads to a loss of cardiac tissue impairment of left ventricular function. The damaged left ventricle undergoes progressive ‘remodelling’ and chamber dilation, with myocyte slippage and fibroblast proliferation. Repair of diseased myocardium with in vitro-engineered cardiac muscle patch/injectable biopolymers with cells may become a viable option for heart failure patients. These events reflect an apparent lack of effective intrinsic mechanism for myocardial repair and regeneration. Motivated by the desire to develop minimally invasive procedures, the last 10 years observed growing efforts to develop injectable biomaterials with and without cells to treat cardiac failure. Biomaterials evaluated include alginate, fibrin, collagen, chitosan, self-assembling peptides, biopolymers and a range of synthetic hydrogels. The ultimate goal in therapeutic cardiac tissue engineering is to generate biocompatible, non-immunogenic heart muscle with morphological and functional properties similar to natural myocardium to repair MI. This review summarizes the properties of biomaterial substrates having sufficient mechanical stability, which stimulates the native collagen fibril structure for differentiating pluripotent stem cells and mesenchymal stem cells into cardiomyocytes for cardiac tissue engineering

A Modest Proposal for the G20

A group of international scholars and policy-makers met in Beijing on 18th of March 2011, to discuss reforms in the international monetary system. There is a general consensus that there is a need for fundamental reforms in that system, which, even if it has not caused recent imbalances and instability in the global economy, has certainly proved ineffective in addressing them. While such reforms will require extensive discussion and deliberation, the consensus of the Beijing Group was that there was a modest proposal which could be adopted this year by the G20: a limited expansion of the current SDR system. This modest proposal, while limited in scope, could be play an important role in initiating discussions of deeper reforms and which would, at the same time, make a modest contribution to restoring the world's fragile economy to health, helping to achieve the aim expressed in the G20 Pittsburgh declaration for a "strong, sustainable and balanced growth"

Multiple Organ System Defects and Transcriptional Dysregulation in the Nipbl+/− Mouse, a Model of Cornelia de Lange Syndrome

Cornelia de Lange Syndrome (CdLS) is a multi-organ system birth defects disorder linked, in at least half of cases, to heterozygous mutations in the NIPBL gene. In animals and fungi, orthologs of NIPBL regulate cohesin, a complex of proteins that is essential for chromosome cohesion and is also implicated in DNA repair and transcriptional regulation. Mice heterozygous for a gene-trap mutation in Nipbl were produced and exhibited defects characteristic of CdLS, including small size, craniofacial anomalies, microbrachycephaly, heart defects, hearing abnormalities, delayed bone maturation, reduced body fat, behavioral disturbances, and high mortality (75–80%) during the first weeks of life. These phenotypes arose despite a decrease in Nipbl transcript levels of only ∼30%, implying extreme sensitivity of development to small changes in Nipbl activity. Gene expression profiling demonstrated that Nipbl deficiency leads to modest but significant transcriptional dysregulation of many genes. Expression changes at the protocadherin beta (Pcdhb) locus, as well as at other loci, support the view that NIPBL influences long-range chromosomal regulatory interactions. In addition, evidence is presented that reduced expression of genes involved in adipogenic differentiation may underlie the low amounts of body fat observed both in Nipbl+/− mice and in individuals with CdLS