States of matter

All of us have read about solid, liquid and gaseous states of matter in school. Are these the only states of matter? What distinguishes different states of matter from each other?     

Think it over

This section of Resonance presents thought-provoking questions, and discusses answers a few months later. Readers are invited to send new questions, solutions to old ones and comments, to ??Think It Over??, Resonance, Indian Academy of Sciences, Bangalore 560 080. Items illustrating ideas and concepts will generally be chosen.     

High efficiency vortex trapping of circulating tumor cells

Circulating tumor cells (CTCs) are important biomarkers for monitoring tumor dynamics and efficacy of cancer therapy. Several technologies have been demonstrated to isolate CTCs with high efficiency but achieve a low purity from a large background of blood cells. We have previously shown the ability to enrich CTCs with high purity from large volumes of blood through selective capture in microvortices using the Vortex Chip. The device consists of a narrow channel followed by a series of expansion regions called reservoirs. Fast flow in the narrow entry channel gives rise to inertial forces, which direct larger cells into trapping vortices in the reservoirs where they remain circulating in orbits. By studying the entry and stability of particles following entry into reservoirs, we discover that channel cross sectional area plays an important role in controlling the size of trapped particles, not just the orbital trajectories. Using these design modifications, we demonstrate a new device that is able to capture a wider size range of CTCs from clinical samples, uncovering further heterogeneity. This simple biophysical method opens doors for a range of downstream interventions, including genetic analysis, cell culture, and ultimately personalized cancer therapy.     

The Bohr correspondence principle

We consider the quantum-mechanical non-relativistic hydrogen atom. We show that for bound states with size much larger than the Bohr radius, one can construct a wave packet that is localized in space corresponding to a classical particle moving in a circular orbit.     

On the Relationship of Mathematics to the Real World

In this article, I discuss the relationship of mathematics to the physical world, and to other spheres of human knowledge. In particular, I argue that mathematics is created by human beings, and the number π cannot be said to have existed 100,000 years ago, using the conventional meaning of the word ‘exist’.     

States of matter

All of us have read about solid, liquid and gaseous states of matter in school. Are these the only states of matter? What distinguishes different states of matter from each other?     

Biodiversity and biological degradation of soil

Soils contain enormous numbers of diverse living organisms assembled in complex and varied communities. Microscopic examination of a soil sample reveals the presence of billions of organisms like nematodes, protozoa, fungi, algae, actinomycetes, bacteria and cyanobacteria. These diverse organisms interact in the ecosystem, forming a complex web of biological activity. Environmental factors, such as temperature, moisture and acidity, as well as human activities such as agricultural and forestry management practices, affect soil biological communities and their functions. Soil biology is an interesting area of soil research and has yielded considerable information that is used in soil fertility management.     

Polymorphisms of CYP1A1, GSTM1 and GSTT1 Loci as the Genetic Predispositions of Oral Cancers and Other Oral Pathologies: Tobacco and Alcohol as Risk Modifiers

Polycyclic aromatic hydrocarbons of tobacco require activation by phase I enzymes, such as cytochrome-P4501A1 (CYP1A1) to become an ultimate carcinogen, which are subjected to detoxification by phase II enzymes, especially glutathione S-transferases (GSTs). A study was designed to find whether genetic predisposition are risk modifiers of oral pathologies. The study included 102 cases with Oral Cancers (OCs), 68 cases with nonmalignant pathologies, 100 cases as control group. GSTM1 null genotype was associated with increased risk of OCs but not with benign pathologies. Deleted GSTT1 was associated with all pathologies. Both m1m2 and m2m2 polymorphisms of CYP1A1 were associated with oral pathologies.     

Performance evaluation of minimum quantity lubrication by vege- table oil in terms of cutting force, cutting zone temperature, tool wear, job dimension and surface finish in turning AISI-1060 steel

In all machining processes, tool wear is a natural phenomenon and it leads to tool failure. The growing demands for high productivity of machining need use of high cutting velocity and feed rate. Such machining inherently produces high cutting temperature, which not only reduces tool life but also impairs the product quality. Metal cutting fluid changes the performance of machining operations because of their lubrication, cooling and chip flushing functions, but the use of cutting fluid has become more problematic in terms of both employee health and environmental pollution. The minimization of cutting fluid also leads to economical benefits by way of saving lubricant costs and workpiece/tool/machine cleaning cycle time. The concept of minimum quantity lubrication （MQL） has been suggested since a decade ago as a means of addressing the issues of environmental intrusiveness and occupational hazards associated with the airborne cutting fluid particles on factory shop floors. This paper deals with experimental investigation on the role of MQL by vegetable oil on cutting temperature, tool wear, surface roughness and dimen- sional deviation in turning AISI-1060 steel at industrial speed-feed combinations by uncoated carbide insert. The encouraging results include significant reduction in tool wear rate, dimensional inaccuracy and surface roughness by MQL mainly through reduction in the cutting zone temperature and favorable change in the chip-tool and work-tool interaction.