Equatorial counter electrojets and polar stratospheric sudden warmings - a classical example of high latitude-low latitude coupling

Favored occurrences of Equatorial Counter Electrojets (CEJs) with a quasi 16-day periodicity over Trivandrum (8.5° N, 76.5° E, 0.5° N diplat.) in association with the polar Stratospheric Sudden Warming (SSW) events are presented. It is observed that, the stratospheric temperature at ˜30 km over Trivandrum shows a sudden cooling prior to the SSWs and the CEJs of maximum intensity which occurs around this time. In general stronger CEJs are associated with more intense SSW events. The stratospheric zonal mean zonal wind over Trivandrum also exhibits a distinctly different pattern during the SSW period. These circulation changes are proposed to be conducive for the upward propagation of the lower atmospheric waves over the equatorial latitudes. The interaction of such waves with the tidal components at the upper mesosphere and its subsequent modification are suggested to be responsible for the occurrence of CEJs having planetary wave periods

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Not AvailableA pot experiment was conducted using two contrasting chickpea varieties, viz., Pusa 362 (Desi type) and Pusa 1108 (Kabuli type) with the objective of optimizing dose of bio-regulators namely thiourea (TU), benzyladenine (BA) and thidiazuron (TDZ). Varying doses of foliar application of TU (0, 500, 1000, 1500 ppm), BA (0, 20, 40, 60 ppm), TDZ (0, 10, 15, 20 ppm) and salicylic acid (0, 50, 100, 150 ppm) were applied before flowering stage. Rates of photosynthesis were recorded at flowering and podding stages and seed yield was obtained at harvest. The results revealed that photosynthetic rate in both varieties increased with increasing doses of bio-regulators at both flowering and podding stages and grain yield also exhibited similar trend. Highest photosynthetic rates and grain yield were recorded with the foliar application of TU, BA, TDZ and SA @ 1000, 40, 10 and 100 ppm, respectively. After curve fitting, optimum dose for TU, BA, TDZ and SA foliar application were estimated to be 878.33, 52.75, 11.78 and 90.63 ppm, respectively.Not Availabl

Analysis of the Multiwalled Carbon Nanotubes Reinforced Polymethyl Methacrylate Bone Cement’s Characteristics and In Vitro Bioactivity to Prolong Its Functionality in Orthopedic Application

Polymethyl methacrylate (PMMA) bone cement is being used to fill voids that are created due to vertebral compression fractures. It is also a grouting medium in orthopedic joint replacement surgeries as they possess fast primary fixation to the bone. Considering the cement properties and in vitro bioactivity of bone cement is essential for cemented hip and knee joint replacement surgeries. In this study, commercial Simplex P bone cement (SPBC) is modified with carboxyl- (-COOH-) functionalized multiwalled carbon nanotubes (MWCNTs) to overcome high polymerization temperature, volumetric shrinkage, surface wettability, and in vitro bioactivity. A geometric dilution method is used to incorporate MWCNTs with the PMMA powder, which is in unequal proportions. The PMMA/MWCNT nanocomposite with different concentrations of reinforcements, such as 0.1, 0.3, 0.5, and 0.7 weight percentages, is prepared for the investigation. It was observed that the MWCNTs had a beneficial impact on PMMA bone cement (PMMA-BC) by enhancing its setting time (2.94%↑) and surface wettability (23.58%↑). Also, diminished polymerization temperature (29%↓) and volumetric shrinkage (40.9%↓) are observed for an optimum concentration of 0.7 wt. %. The bioactivity of the cement surface is validated by the in vitro bioactivity observed in simulated body fluid (SBF) through the development of primary and secondary apatite. It is concluded that the synthesized PMMA/MWCNT nanocomposites are found to have enhanced cement properties compared to PMMA-BC

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Not AvailableTo explore the effect of salt stress on photosynthetic traits and gene expression in Indian mustard, four genotypes CS 54 (national check for salinity), CS 52-SPS- 1-2012 (salt tolerant mutant), CS 614-4-1-4-100-13 (salt sensitive mutant) and Pusa bold (high yielding variety) were evaluated under irrigation water salinity (ECiw 12, and 15 dS m-1). Results suggest genotype CS 52-SPS-1- 2012 followed by CS 54 performed better under imposed salt stress due to differential regulation of Na? accumulation in the roots and main stem, restriction of Na? influx from root to shoot, maintaining higher net photosynthetic traits under saline stress compared to CS 614-4-1-4-100-13 and Pusa bold. Further, overexpression of antiporters (SOS1, SOS2, SOS3, ENH1 and NHX1) and antioxidant (APX1, APX4, DHAR1 and MDHAR) genes in salt tolerant genotypes CS 52-SPS-1-2012 and CS 54 demonstrated their significant role in imparting salt tolerance in Indian mustard.Not Availabl

Determination of day-time OH emission heights using simultaneous meteor radar, day-glow photometer and TIMED/SABER observations over Thumba (8.5°N, 77°E)

Simultaneous day-glow photometer and meteor radar observations are used for determining the day-time OH emission height for the first time over Thumba (8.5° N, 77° E). The meteor radar observations are extensively used to obtain the ambipolar diffusion coefficient (D<SUB>a</SUB>) profile in the 82-98 km height region and are compared with OH rotational temperature (TOH) measurements. The height profile of correlation coefficient between D<SUB>a</SUB> and TOH showed a maximum at 90 km. These ground based estimates are then compared with space based OH volume emission rate (VER) observations by TIMED/SABER satellite over this latitude, which showed an excellent agreement. Further, the temporal variation of OH emission heights showed tidal modulation of OH emission heights. The significance of the present results lies in determining the day-time OH emission height for the first time using collocated radar and photometer observations, which will have implications in interpreting TOH in the MLT region

Signatures of low latitude–high latitude coupling in the tropical MLT region during sudden stratospheric warming

The present paper analyses the variations of daytime mesopause temperature over an equatorial station during polar Stratospheric Sudden Warming (SSW) events, indicating a possible dynamical coupling between the two regions, through the intensification of planetary wave activity. The amplified wave signatures of quasi-16 day period have been seen in the Equatorial Mesopause Temperature (EMT) and Polar Stratospheric Temperature (at 10 hPa) during the course of the SSW. The EMT measurements were made from Trivandrum (8.5°N, 76.5°E), an equatorial station in India and the stratospheric temperatures were obtained from NCEP/NCAR reanalysis. This investigation reveals (1) an overall enhancement and amplified wave activity in the EMT prior to the SSW and (2) propagation of a wave disturbance from equatorial stratosphere to North Pole in about a month. These results are new and reveal some newer aspects of the SSW and its equatorial effects