Ashoke sen and S-duality

The Fundamental Physics Prize Foundation declared names of nine scientists in a variety of areas of theoretical physics as recipients of the Fundamental Physics Prize. This article is a quick introduction to Ashoke Sen’s scientific achievements. In addition, this article contains some discussion of his S-duality proposal and the Sen conjecture, which fetched him the Fundamental Physics Prize.     

Some physics inside drying droplets

Droplets are of great scientific interest because studying their formation and dynamics is important in many technologies such as in microfluidics [1, 2]. Evaporation of droplets is another interesting aspect that has caught much scientific attention. An example of an evaporating droplet is a coffee droplet spilled on a table. After evaporation the coffee droplet leaves a ring-like stain called a coffee ring or coffee stain [3]. This phenomenon, known as the ‘coffee ring effect’, occurs not only with coffee droplets but also with all droplets containing non-volatile solutes. There are a number of interesting physical processes going on within the droplets during evaporation to form the ‘coffee stains’. In this article, we will see what they are.     

Sample preconcentration inside sessile droplets using electrowetting

Electrowetting with alternate voltage (AC) creates azimuthal flow vortices inside sessile droplets. These flow vortices can be controlled by introducing pinning sites at the contact line. When the frequency of the applied AC voltage is gradually ramped from a few hundreds of hertz to a few tens of kilohertz the azimuthal flow vortices contract and move towards the contact line near the pinning site. Dispersed particles in the liquid are collected in the center of these vortices leading to an increase in the local particle concentration by up to more than one order of magnitude. We provide a qualitative explanation for symmetry of the flow patterns within the drops and discuss possible scenarios explaining the particle collection and preconcentration.     

Microfluidics — a lab in your palm

A few decades ago electronics evolved from huge circuits based on vacuum tubes into small scale semiconducting integrated circuits. In simple words, a calculator that was as huge as a room, now fits into a wrist watch. Nowadays, a similar trend is observed in bio and chemical engineering. Analysis and synthesis involving fluids, which originally could be done only on large scales, are more and more integrated into small devices called microfluidic chips. Such microsacle or even nanoscale devices, in general called lab-on-a-chip devices, offer a higher accuracy and better efficiency compared to bulk devices. In this article we describe some important aspects about microfluidics.     

Biochemical Effects of Lead Exposure on Systolic &; Diastolic Blood Pressure,Heme Biosynthesis and Hematological Parameters in Automobile Workers of North Karnataka (India)

The purpose of this study was to find out the effect of lead exposure on systolic and diastolic blood pressure, heme biosynthesis related and hematological parameters of automobile workers. For this study 30 automobile workers were selected and compared with 30 age matched healthy control subjects. Significantly increased blood lead (364%, P < 0.001) and urinary lead (176%, P < 0.001) levels were observed in automobile workers (study group) as compared to controls. Systolic blood pressure (5.32%, P < 0.05) and diastolic blood pressure (5.87%, P < 0.05) were significantly increased in the automobile workers as compared to controls. The significantly decreased non-activated erythrocyte δ-aminolevulinic acid dehydratase (δ-ALAD) (−18.51%, P < 0.01) and activated δ-ALAD (−13.29%, P < 0.05) levels were observed in automobile workers as compared to normal healthy control subjects. But the ratio of activated/non-activated δ-ALAD was significantly increased (43.83%, P < 0.001) in automobile workers as compared to controls. Excretions of δ-aminolevulinic acid (83.78%, P < 0.001) and porphobilinogen (37%, P < 0.001) in urine were significantly increased in the study group as compared to the controls. In automobile workers heamoglobin (−11.51%, P < 0.001), hematocrit (−4.06%, P < 0.05), mean corpuscle volume (−3.34%, P < 0.05), mean corpuscle hemoglobin (−5.66%, P < 0.01), mean corpuscle hemoglobin concentration (−7.67%, P < 0.001), red blood cell count (−14.6%, P < 0.001) were significantly decreased and total white blood cell count (11.44%, P < 0.05) increased as compared to the controls. The results of this study clearly indicate that the absorption of lead is more in automobile workers and it affects on blood pressure, heme biosynthesis and hematological parameters observed in this study group.