Nondestructive evaluation of structural ceramics by photoacoustic microscopy

A photoacoustic microscopy (PAM) digital imaging system was developed and utilized to characterize silicon nitride material at the various stages of the ceramic fabrication process. Correlation studies revealed that photoacoustic microscopy detected failure initiating defects in substantially more specimens than microradiography and ultrasonic techniques. Photoacoustic microscopy detected 10 to 100 micron size surface and subsurface pores and inclusions, respectively, up to 80 microns below the interrogating surface in machined sintered silicon nitride. Microradiography detected 50 micron diameter fracture controlling pores and inclusions. Subsurface holes were detected up to a depth of 570 microns and 1.00 mm in sintered silicon nitride and silicon carbide, respectively. Seeded voids of 20 to 30 micron diameters at the surface and 50 microns below the interrogating surface were detected by photoacoustic microscopy and microradiography with 1 percent X-ray thickness sensitivity. Tight surface cracks of 96 micron length x 48 micron depth were detected by photoacoustic microscopy. PAM volatilized and removed material in the green state which resulted in linear shallow microcracks after sintering. This significantly limits the use of PAM as an in-process NDE technique

Private Savings and its Influence on Economic Growth in India in the Post Reform Period

Neo-Classical growth models show a clear relationship between savings and economic growth and consider savings a prerequisite for faster growth in an economy. Private savings in India have been a major contributor to total savings for several years. In this context, it is essential to investigate the long-run causality relationship between private savings and economic growth. It is also important, for their policy implications, to identify various determinants of private savings and analyse their impact in driving private savings. The study covers the period from 1991 to 2014 and uses the Engel-Granger cointegration test to find the direction of causality. To capture the degree of impact of various determinants on private savings ARDL model has been employed. The results show that growth in GDP and private savings in India are cointegrated and have a unilateral long-run relationship. It was found that changes in lending rates, causes a change in private savings. Other variables do not have a significant impact on private savings in India

Age-dependent increase in green autofluorescence of blood erythrocytes

Green auto-fluorescence (GAF) of different age groups of mouse blood erythrocytes was determined by using a double in vivo biotinylation (DIB) technique that enables delineation of circulating erythrocytes of different age groups. A significant increase in GAF was seen for erythrocytes of old age group (age in circulation >40 days) as compared to young erythrocytes (age <15 days). Erythrocytes are removed from blood circulation by macrophages in the reticulo-endothelial system and depletion of macrophages results in an increased proportion of aged erythrocytes in the blood. When mice were depleted of macrophages for 7 days by administration of clodronate loaded liposomes, the overall GAF of erythrocytes increased significantly and this increase could be ascribed to an increase in GAF of the oldest population of erythrocytes. Using the DIB technique, the GAF of a cohort of blood erythrocyte generated during a 5 day window was tracked in vivo. GAF of the defined cohort of erythrocytes remained low till 40 days of age in circulation and then increased steeply till the end of the life span of erythrocytes. Taken together our results provide evidence for an age dependent increase in the GAF of blood erythrocytes that is accentuated by depletion of macrophages. Kinetics of changes in GAF of circulating erythrocytes with age has also been defined

Ultraslow Electron Spin Dynamics in GaAs Quantum Wells Probed by Optically Pumped NMR

Optically pumped nuclear magnetic resonance (OPNMR) measurements were performed in two different electron-doped multiple quantum well samples near the fractional quantum Hall effect ground state nu=1/3. Below 0.5K, the spectra provide evidence that spin-reversed charged excitations of the nu=1/3 ground state are localized over the NMR time scale of ~40 microseconds. Furthermore, by varying NMR pulse parameters, the electron spin temperature (as measured by the Knight shift) could be driven above the lattice temperature, which shows that the value of the electron spin-lattice relaxation time lies between 100 microseconds and 500 milliseconds at nu=1/3.Comment: 6 pages (REVTEX), 6 eps figures embedded in text; published version; minor changes to match published versio

Testing alternative fuels, solar-thermal systems

The Terrestrial Energy Systems Technical Committee works to advance the application of engineering sciences and systems engineering to the production, storage, distribution and conservation of energy for terrestrial uses

Variety In, Variety Out: Imported Input and Product Scope Expansion in India

This chapter discusses and extends the findings of recent research which examines the role of imported inputs in fostering domestic product growth in India. India's trade liberalization during the 1990s resulted in substantial increases in the volume and variety of imported inputs. This period also witnessed an expansion of product lines by Indian firms. We explore the causal relationship between increased access to imported inputs through lower input tariffs and the subsequent increase in firms' product mix. Our analysis suggests that lower input tariffs accounted for at least 8 percent of overall manufacturing growth. We examine firm-level imported input use in detail, and explore heterogeneity of the impact across industries and states, as well as examine the robustness to other policy reforms implemented during this period