Mechanical wear behavior of nanocrystalline and multilayer diamond coatings on temporomandibular joint implants

We used microwave plasma chemical vapor deposition to deposit nanocrystalline and multilayer (nanocrystalline/microcrystalline/nanocrystalline) diamond thin films on Ti-6AI-4V substrates imitating the condyle and fossa components of the temporomandibular joint. We tested the condyle/fossa pairs for wear in a mandibular movement simulator for an equivalent of two years of clinical use. Analysis of the wear surfaces by optical microscopy, scanning electron microscopy (SEM), and Raman spectroscopy showed that damage in both the films was minimal, no loss of film occurred and the wear performance was superior for the multilayer film. Comparisons with an uncoated condyle/fossa pair showed that the coated temporomandibular joint pairs had improved wear performance.     

Some aspects of biomedical engineering research in New Delhi

Biomedical engineering has been recognized in India for the last decade. Technological developments have been in areas of importance to the country, with several groups actively involved in the promotion of bioengineering, particularly in New Delhi. A group at the National Physical Laboratory has contributed significantly to the field of ultrasonics as well as to the development of piezoelectric transducers for other biomedical uses. The Centre for Biomedical Engineering of the Indian Institute of Technology and the All India Institute of Medical Sciences is one of the country's leading centres producing outstanding work in areas like instrumentation, rehabilitation, biomaterials, modelling and analysis. Research in technology applied to reproductive physiology (an area especially relevant to India's needs) was initiated at this centre. Research at the School of Environmental Sciences, Jawaharlal Nehru University has elucidated the effects and mechanisms of the action of low-energy electromagnetic radiation and ultrasound on biological systems--in one of the school's projects the use of bone material for ultrasonic transducers and optical detectors was successfully demonstrated. A selected list of publications shows the wide spectrum of research carried out at these institutions.     

Particle Characterization and Settling Velocities for a Water Supply Reservoir during a Turbidity Event

Characterization of the particle population for a location in a water supply reservoir, Kensico Reservoir, N.Y., is documented for a high turbidity event, from its onset, through alum treatment and its waning. Supporting in situ measurements included the beam attenuation coefficient at 670?nm (c670) and 660?nm (c660) [surrogates of turbidity (Tn)], particle concentrations (N) and size distributions (PSDs), and size class specific settling velocities (SVs). Laboratory measurements included chemical and morphometric analyses of individual particles, and routine measurements of Tn. The turbidity is shown to be primarily derived from clay minerals, mostly in the size range of 1.5–6?μm. An initial high c670 level (40?m?1;Tn ～ 100?NTU) decreased sevenfold in less than 1?week in response to alum treatment that largely eliminated the particle size classes responsible for the elevated turbidity. Successful SV experiments, made using a laser in situ scattering and transmissometry (LISST) instrument, for seven particle size classes in the range of 1.25–129?μm yielded SV values of 0.17–69.4?m?day?1. Size classes larger than ～ 5?μm settled much slower than Stokes law predictions, before alum treatment, indicating that these classes existed as porous flocs or aggregates. Decreases in SVs following treatment suggest changes in floc character consistent with increased porosity. In situ measurements of c670, N, PSDs, and SVs can contribute to the development and testing of a multiple particle size class model to simulate fate, transport, and impacts of suspended particles.     

Improved bounds for large scale capacitated arc routing problem

The Capacitated Arc Routing Problem (CARP) stands among the hardest combinatorial problems to solve or to find high quality solutions. This becomes even more true when dealing with large instances. This paper investigates methods to improve on lower and upper bounds of instances on graphs with over 200 vertices and 300 edges, dimensions that, today, can be considered of large scale. On the lower bound side, we propose to explore the speed of a dual ascent heuristic to generate capacity cuts. These cuts are next improved with a new exact separation enchained to the linear program resolution that follows the dual heuristic. On the upper bound, we implement a modified Iterated Local Search procedure to Capacitated Vehicle Routing Problem (CVRP) instances obtained by applying a transformation from the CARP original instances. Computational experiments were carried out on the set of large instances generated by Brandão and Eglese and also on the regular size sets. The experiments on the latter allow for evaluating the quality of the proposed solution approaches, while those on the former present improved lower and upper bounds for all instances of the corresponding set.     

Ground-based method for measuring thermal infrared effective emissivities: Implications and perspectives on the measurement of land surface temperature from satellite data

Thermal infrared emissivity is an important parameter for surface characterization and for determining surface temperature. The field-based measurements for ground and vegetation emissivities in 8-14 w m waveband were performed with an emissivity box. A theoretical analysis was carried out using the box and a correcting factor has been determined. The average value for thermal band emissivity of the exposed bare soil was found to be around 0.909; the average value measured for most of the varieties of vegetation present were in the range of 0.980-0.985. A theoretical model is used for obtaining effective emissivity in the 8-14 w m region from Advanced Very High Resolution Radiometer (AVHRR) data considering the proportion of vegetation cover in a pixel and the field-measured emissivity values. The error of the methodology is found to be within 1.5%. Narrow band emissivities for AVHRR channels 4 and 5 have been derived from the emissivity values in the 8-14 w m waveband. The surface temperature has been derived from AVHRR data using a split-window algorithm as a function of emissivities derived in narrow bands. The split-window algorithm accounted for absorption effects of the atmosphere by incorporating the water vapour concentration measured in the campaign. A good agreement was obtained between the satellite-derived surface temperature and the in situ observations. The result suggest that the methodology allows us to derive land surface temperature with an accuracy better than 1.5° C provided the surface emissivity is known. The paper describes the field-based emissivity measurement and approach for deriving surface temperature over land surface.     

Biomass burning and related trace gas emissions from tropical dry deciduous forests of India: A study using DMSP-OLS data and ground-based measurements

Biomass burning is one of the major sources of trace gas emissions in the atmosphere. In India the major sources of biomass burning include deforestation, shifting cultivation, accidental fires, controlled burning, fire wood burning, burning from agricultural residues and burning due to fire lines. Studies on biomass burning practices gain importance due to increasing anthropogenic activities and increasing rates of deforestation. Satellite data have been widely used over the globe to monitor the rates of deforestation and also with respect to biomass burning studies. But, much of the polar orbiting satellites, due to their repetitive cycle, have limitations in observing such events and in the tropics, due to cloud cover, getting a cloud-free image during the daytime is difficult. In this study we used Defence Meteorological Satellite Program Operational Line Scanner (DMSP-OLS) night-time data to study the biomass burning events over a period of 10 years from 1987 to 1998 for the Eastern Ghats region, covering the northern part of Andhra Pradesh, India. Two ground-based experiments were carried out to quantify the emissions from biomass burning practices. The results of the study with respect to trace gases suggested emission ratios for CO, CH4, NOx and N20 during the burning to be about 12.3%, 1.29%, 0.29% and 0.07% at the first site and 12.5%, 1.59%, 0.29% and 0.05% at the second site, suggesting low inter-fire variability between the sites. The variation has been attributed to the fuel load, vegetation characteristics, site conditions and local meteorological parameters affecting the relative amounts of combustion. Using the DMSP OLS derived areal estimates of active fires, the trace gas emissions released from the biomass burning were quantified. The results suggested the emissions of 8.2 2 10 10 g CO 2, 1.8 2 10 8 g CO, 6.0 2 10 6 g N 2 O, 3.0 2 10 6 g NO x and 1.2 2 10 8 8 g CH 4 during March 1987. The emissions increased to 1.0 2 10 11 g CO 2, 2.3 2 10 g CO, 7.8 2 10 6 g N 2 O, 3.9 2 10 7 g NO x and 1.6 2 10 8 g CH 4, over a period of 10 years. The results of the analysis suggest the possible use of monitoring biomass burning events from DMSP-OLS night-time data.     

The influence of mesoscale eddies on a commercial fishery in the coastal waters of the Andaman and Nicobar Islands,India

Mesoscale eddies enhance the productivity in a stratified coastal environment by upwelling. The seas around the Andaman and Nicobar Islands have been found to have frequent mesoscale eddy activity. Commercial fishing grounds coincide with upwelling areas associated with cyclonic and anticyclonic eddies and also with areas between two adjacent eddies. There are different eddy zones supporting different types of fishing gears and fish. The current study aims at identifying the different zones of mesoscale eddies in the Andaman Sea and compares the productivity and fishing activity in each of them. Data collected from 454 commercial fishing trips in the Andaman Sea along with maps of sea level anomaly and Moderate Resolution Imaging Spectroradiometer (MODIS) global level 3 mapped thermal infrared (IR) daytime sea surface temperature (SST) from the Aqua and Terra satellites were used for the study. Known upwelling areas such as the periphery of anticyclonic and the core of cyclonic eddies showed higher catches in longlines, ring seines among the fishing gears, and among all the fish species groups. Downwelling areas such as the periphery of cyclonic and the core of anticyclonic eddies showed lower catches with ring seines and the fish species groups. Areas in between adjacent eddies were explored in this study and the fish captures in such areas were found to be different with types of fishing and the target fish group. The study shows results that link eddy activity with the performance of a fishery.     

Satellite- and ground-based measurements of CO2 over the Indian region: its seasonal dependencies,spatial variability,and model estimates

ABSTRACT

The present study demonstrates the distribution of carbon dioxide (CO₂) concentration over the Indian region and the surrounding oceanic regions during 2009–2012, using measurements from satellites viz., Greenhouse Gases Observing Satellite (GOSAT) and Atmospheric Infrared Sounder, Carbon Tracker (CT) model simulations and flask measurements from two Indian stations Sinhagad (SNG) (73°45′ E, 18°21′36″ N) and Cape Rama (CRI) (73°54′ E, 15°6′ N). The concentration of CO₂ is observed to be maximum during pre-monsoon and shows a decreasing phase during the post-monsoon season. In a regional scale, it is found that Indo-Gangetic Plain and northern India have relatively higher concentrations compared to the other regions. The probability distribution of the concentration differences shows that for most of the time, the differences lie between ±3 ppmv between GOSAT and CT. The comparison between the CO₂ flask measurements over SNG and CRI with respect to that of GOSAT and CT clearly reveals that the differences in CO₂ are as high as 10 ppmv between the ground- and satellite-based measurements. Further, we utilized the Lagrangian model FLEXible PARTicle (FLEXPART) to understand the source?receptor relationship over CRI, SNG, and over the equatorial Indian Ocean (IO). The source contributions from the northern and eastern continental regions of the Indian region are found to be more influential over SNG compared to CRI. It is also found from simulations that the equatorial IO has less influence from the continental source and therefore has a reduced seasonal variability compared to the other regions considered in the present study.     

Reversible Z-E Isomerism and Pharmaceutical Implications for SU5416

ABSTRACT

SU5416 (Z-isomer), the first in its class of angiogenesis inhibitors, in solution converts to the E-isomer following light exposure and reverts to the Z-isomer in the dark. Kinetics of this Z-E isomerism in pharmaceutical media is reported. Analytical solutions need light protection at 5°C to maintain integrity. While E-isomer in light-exposed product increased to 0.9% in 24 hours, light-protected product showed no change (25°C, 18 months). Infusate studies indicated that < 1.9% E-isomer will be dosed to patients and would likely convert to the Z-isomer, following administration. This report implies Z-E isomerism in SU5416 is controllable with no limitations towards ensuring pharmaceutical product quality.     

A Device for Generating Singly Charged Particles in the 0.1–1.0-μm Diameter Range

In this paper an aerosol charger that largely avoids the production of multiply charged particles in the 0.1–1.0 μm diameter range is described. The input aerosol is first passed through an electrostatic condenser to remove all charged particles and ions. The remaining neutral aerosol then flows into a 23-cm-long, 2.1-cm inner diameter cylindrical tube; the inner surface of this tube is uniformly coated with 0.09 μCi⁶³ Ni, a 0.067 MeV β-emitter with a half-life of 92 years. At typical airflow rates of 0.2–1.0 lpm, this low-activity source of ionizing radiation produces bipolar ion concentrations ranging from 1 × 10⁴ to 9 × 10⁴ ion/cm³, which is much lower than levels required to bring the aerosol to Boltzmann charge equilibrium. At a flow rate of 1.0 lpm, particles smaller than about 1.0 μm typically interact with no more than one ion en route through the charger. Therefore, particles at the charger exit are mostly either neutral or singly charged. Charge distributions of initially-neutral mono-disperse polystyrene latex particles were measured at the exit from the charger for particle diameters ranging in size from 0.09 to 1.09 μm. It was found that, at an airflow rate of 1.0 lpm and particle size 1.09 μm, the ratios of singly, doubly, and triply charged to total positively charged concentrations were 0.75, 0.19, and 0.06 respectively; particles with more than three charges were not detected. In contrast, the analogous charge ratio at Boltzmann equilibrium is 0.28 (+ 1), 0.24 (+ 2), 0.19 (+ 3), 0.13 (+ 4), 0.08 (+ 5), 0.05 (+ 6), and 0.7 (+ 02).