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In recent years, interest in the thermal properties of graphene constituents has seen rapid growth in the fields of science and engineering. The removal of heat in the continuous processes in the electronics industry has had major issues in thermal transmission in lower-dimensional assemblies. It has also shown fascinating topographies as the carbon allotropes and their derivative compounds expel heat. Numerous research articles reported within the past 15 years have demonstrated enhanced electron flexibility, exceptional thermal conductivity and mechanical behaviour, as well as excellent optical properties of graphene as a single atomic layer. This review article tries to provide a detailed summary of the heat exchange properties of graphene structures and graphene-based materials such as nanoribbons with few-layered graphene. Thermal and energy storage management systems have played a major role in the increase in marketable products in recent times. The purpose of this review is to summarize the current research on thermal properties with regard to the management and energy storage of graphene materials, focusing on characteristic properties, industrialization, modelling and simulation, and their applications in specific thermal storage systems.

In the recent decades, the use of aluminum alloy has significantly enhanced especially in engineering applications extensively used in shipbuilding, aircraft, structural and automobile applications such as crankshaft, connecting rod and piston etc. This paper illustrates a comprehensive investigation on mechanical behavior of AA6061/Titanium diboride (TiB2)/Silicon carbide (SiC) composites joined by friction stir welding using cylindrical pin tool profile. Various sets of metal matrix composites were prepared by varying TiB2/SiC composition percentages in aluminum matrix using stir casting process. This process is followed by welding of samples by controlled input process parameters. Subsequently, microscopic analysis is performed on the various weld zones namely heat affected zone, thermo-mechanically affected zone and stir zone to observe the grain size and distribution of reinforcement ceramic particles in the matrix. Hardness and tensile tests are carried out to assess the strength of the weldment. Results emphasize that the ultimate tensile strength of the welded specimens is proportional to the weight percentage of TiB2 in the matrix. The maximum hardness observed is 135.56 HV which is marginally greater than the aluminum matrix. Percentage elongation also increased by 2.5% thereby improving the weld specimen’s ductile property.

Recent studies have shown that the Atlantic zonal mode (AZM) can significantly influence the Indian summer monsoon (ISM). In an earlier study, we proposed that AZM influence propagates in tropospheric temperature as Kelvin wave-like features to the east to reach the Indian Ocean and influences the monsoon by modulating the mid-tropospheric land-sea thermal gradient and thereby the seasonal mean flow. The changes thus induced in the mean flow were shown to affect the monsoon depressions in the Bay of Bengal and rainfall over India. In the present study, we use the Coupled Forecast System version 2, which is utilized for seasonal prediction of ISM in India, to examine how well the model simulates this AZM-monsoon link. In the sensitivity experiment, a warm AZM SST anomaly is added over the tropical Atlantic in the boreal summer and the ISM response is studied. We find that the model simulates the important aspects of the AZM-monsoon link. The model also simulates a known dynamics-based mechanism wherein a warm AZM SST anomaly produces a Matsuno-Gill type response, which in turn induces a sinking motion over India causing a reduction in rainfall. However, some finer details of these mechanisms are not simulated due to mean state biases in the tropical Atlantic in the model, a problem common to many coupled models. Our study highlights the need for the improvement of mean state of model in the tropical Atlantic to better capture the AZM-ISM relationship which will ultimately improve the monsoon forecasts issued using this model.

Al-Si based alloy matrix composites are now broadly utilized by the industrial sectors like automobile, structural, aerospace and more practical industrial applications due to its noncompetitive economy range, good mechanical properties and less density. In order to widen its applications, it is very significant to improve its mechanical and workability behavior. So, in this work, an effort has been taken to develop a ZnO microparticles (3, 4.5 & 6 %) reinforced with Al-Si-Mg (AA6061) alloy by stir casting route.Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction analysis (X-RD) were employed for characterization studies of the composites. Tensile and hardness of the composites are investigated, compared and analyzed its effects. Another novel finding of the work is determining the workability behavior of the prepared samples with aspect ratio of 1 by incremental compressive loading of 25 kN through cold upsetting technique. For all developed samples, true axial stress (σz), hoop stress (σө), hydrostatic stress (σm), effective stress (σeff), formability stress index (β) and stress ratio parameters [(σz/σeff), (σө/σeff), (σm/σeff)] were determined and the results are correlated with the axial strain (ez). The results clearly infers that increasing weight contributions of ZnO particles increase the mechanical properties, all the stresses and stress ratio parameters of the composites.

The Seychelles-Chagos Thermocline Ridge (SCTR) is a key region which plays a major role in various regional climatic processes at all time scales. The vertical mixing at the base of mixed layer may be climatically important at this region, where a shallow thermocline and highly variable wind activity exists. In this study, we provide evidence of strong vertical mixing at the base of mixed layer and thermocline associated with near-inertial waves (NIWs) using the microstructure profiler time series data during boreal summer 2014. During the study, it was observed that the surface turbulent layer was mostly confined in the mixed layer with turbulent kinetic energy dissipation rate of the order of 10−6 Wkg−1. Elevated dissipation rate in the order of 10−7–10−6 Wkg−1 was also observed at the base of the mixed layer and thermocline (60–100 m) during the entire period of observation. The estimated vertical diffusive heat flux across the mixed layer base (100 Wm−2) was strong and a moderate downward flux (~ 30 Wm−2) was noticed in the thermocline region. The analysis showed that the strong NIW triggered by a strong wind event were responsible for the high dissipation rate at the base of mixed layer and at deeper depths. The higher-mode NIW create elevated vertical shear at the base the mixed layer, which leads to the enhanced mixing. The study also showed the possible role of internal tides on the subsurface mixing in the region. The NIW-induced mixing may have important role on the mixed layer heat balance in a climatically active SCTR.

In this study, a simulation-based optimization technique is employed to reduce nanoparticle deposition rate in a 90° square duct system. Nanoparticle deposition in the 90° bend pipe is highly influenced by bend radius, aspect ratio, airflow velocity, nanoparticle size, and mass flow rate. These factors are optimized for minimum deposition rate through Taguchi’s signal to noise ratio analysis and response surface methodology (RSM). L27 orthogonal array is employed in Taguchi's technique, and a central composite with 32 trials is used in the RSM technique. All the above cases are numerically simulated in computational fluid dynamics (CFD) tool using large eddy simulation (LES) and discrete phase model (DPM) for turbulence modeling. The minimum deposition rate of nanoparticles on the bend of a 90° square duct is predicted as 0.1389 through a confirmative test conducted for the best optimum values. The bend radius is the most influencing factor in the ANOVA analysis of deposition rate, and the other factors have shown the least influence on the deposition rate of nanoparticles.

An Electrical discharge machining (EDM) process is most essential in the machining of hard and complex geometrical material which is difficult to machine by conventional machining technique. The EDM process parameters namely electrode material, pulse current, pulse-on time and pulse-off time are significantly influence the machining performance characteristics, such as material removal rate (MRR) and tool wear rate (TWR). Hence, in the present study, the influence of EDM parameters on the MRR and TWR are examined during machining of Al-Fe-Si alloy (AA8011) filled with 15 wt.% ZrO2 composite fabricated through stir casting route. The experimental work was performed according to the L27 (34) orthogonal array using Taguchi design of experiments (DOE). A Taguchi method and Technique for order of preference by similarity to ideal solution(TOPSIS) has been used to investigate the multiple performance characteristics with an objective to maximize the MRR and minimize the TWR. Moreover, analysis of variance (ANOVA) has been employed to bring out the influence of the EDM parameters associated with each performance characteristics. Main effect plot shows that, the maximum MRR with minimum TWR are obtained by the optimum level of parameters are electrode material of EN-8, pulse current at 15amps, pulse-on time at 900 μs and pulse-off time at 60 μs. From ANOVA analysis, electrode material and pulse current are the most influencing parameters on the MRR and TWR. Finally, the confirmation experiment was conducted to verify the prediction of the results attained by the optimum EDM parameters combination.

This study shows the active role of subsurface ocean temperature in the evolution of coupled intra-seasonal oscillation (ISO) in the Bay of Bengal (BoB) using multi-satellite observations and ocean analysis product. Satellite-derived humidity profiles obtained from the atmospheric infrared sounder (AIRS) show that intense rains over the BoB are associated with the moistening (drying) in the lower and mid-troposphere during the active (break) phase of summer intraseasonal oscillation (ISO). Anomalous moistening in the mid-troposphere up to 500 hPa ahead of the maximum precipitation band over north BoB gives a precursor signal for the northward movement of the rain band. During the active (break) phase, the upper-tropospheric positive (negative) temperature anomaly ahead of the maximum rain band also sets a precondition by heating the mid- to upper troposphere. Daily subsurface temperature from Global Ocean Data Assimilation System (GODAS) analysis show that during the active phase, tropospheric moistening (drying) coincides with the subsurface warm (cold) temperature up to 200-m depth. The upper ocean warms uniformly by ~ 1 °C during the active phase as compared to the break phase in the entire BoB. The presence of a thin warm layer below the maximum rain band creates an environment conducive to sustaining the active phase on the ISO time scale. A positive sea surface temperature (SST) anomaly along with upper ocean warming ahead of a rain band in the north BoB in association with lower and mid-tropospheric moistening sets a precondition for the northward movement of the rain band. The anomalous warming (cooling) in the thermocline is associated with deeper (shallower) thermocline depth [23° isotherms (D23)] and coincides with the mixed-layer warming.

We explore the decadal variability of teleconnection from tropical Pacific to the Indian summer monsoon rainfall (ISMR) using various observational and Reanalysis datasets for the period 1958–2008. In confirmation with the earlier findings, we find that the interannual correlations between the various SST indices of ENSO and ISMR have continued to weaken. Interestingly, we find that even the robust lead correlations of the tropical pacific warm-water-volume with ISMR have weakened since late 1970s. Our analysis suggests that there is a relative intensification of the cross-equatorial flow from the southern hemisphere into the equatorial Indian Ocean associated with ISMR due to strenghtening of Mascarene High. Further, a shift in the surface wind circulation associated with monsoon over the northern pacific since late 1970s has resulted in a strenghtened cyclonic seasonal circulation south-east of Japan. These changed circulation features are a shift from the known circulation-signatures that efficiently teleconnect El Nino forcing to South Asia. These recent changes effectively weakened the teleconnection of the El Nino to ISMR.

Using satellite and in-situ observations, ocean reanalysis products and model simulations, we show a distinct reversal of the North Indian Ocean (NIO, north of 5°S) sea level decadal trend between 1993–2003 and 2004–3013, after the global mean sea level rise is removed. Sea level falls from 1993 to 2003 (Period I) but rises sharply from 2004 to 2013 (Period II). Steric height, which is dominated by thermosteric sea level of the upper 700 m, explains most of the observed reversal, including the spatial patterns of sea level change. The decadal change of surface turbulent heat flux acts in concert with the change of meridional heat transport at 5°S, with both being driven by decadal change of surface winds over the Indian Ocean, to cause sea level fall during Period I and rise during Period II. While the effect of surface net heat flux is consistent among various data sets, the uncertainty is larger for meridional heat transport, which shows both qualitative and quantitative differences amongst different reanalyses. The effect of the Indonesian Throughflow on heat content and thus thermosteric sea level is limited to the South Indian Ocean, and has little influence on the NIO. Our new results point to the importance of surface winds in causing decadal sea level change of the NIO.

Waspaloy is often used in aviation combustion chamber at extreme environments. Waspaloy is also a nickel-based superalloy with exceptional strength properties at a temperature of 980 °C. In this experimental investigation, waspaloy is used to analyse the kerf angle (KA), surface roughness (SR) and material removal rate (MRR) during abrasive water jet machining. The effect of various parameters such as traverse speed, abrasive flow rate, water pressure and stand-off distance on KA, MRR and SR was discussed. The striation formation was analysed for different set of process parameters. The striations were also analysed using atomic force microscopy. An attempt was done to relate the jet impinging angle and nature of striation formation. It was found that the increase in declination angle decreases the formation of striation during water jet process of waspaloy.

Direct current measurements observed from the acoustic Doppler current profilers in the equatorial Indian Ocean (EIO) and solutions from an ocean general circulation model are investigated to understand the dynamics of the Wyrtki jet. These jets are usually described as semiannual direct wind forced zonal currents along the central and eastern EIO. We show that both, spring and fall, Wyrtki jets show predominant semiannual spectral peaks, but significant intraseasonal energy is evident during spring in the central and eastern EIO. We find that for the semiannual band, there is a strong spectral coherence between the overlying winds and the currents in the central EIO, but no coherency is observed in the eastern part of the EIO. Moreover, for the intraseasonal band, strong coherency between the winds and currents is evident. During spring, intraseasonal currents induced by the Madden–Julian oscillation (MJO) superimpose constructively with semiannual currents and thus intensify the strength of the spring Wyrtki jet. Also, the atmospheric intraseasonal variability accounts for the interannual variabilities observed in spring Wyrtki jets.

Eastern equatorial Indian ocean (EEIO) is one of the most climatically sensitive regions in the global ocean, which plays a vital role in modulating Indian ocean dipole (IOD) and El Nino southern oscillation (ENSO). Here we present evidences for a paradoxical and perpetual lower co-variability between sea-surface temperature (SST) and air-temperature (Tair) indicating instantaneous thermal decoupling in the same region, where signals of the strongly coupled variability of SST anomalies and zonal winds associated with IOD originate at inter-annual time scale. The correlation minimum between anomalies of Tair and SST occurs in the eastern equatorial Indian ocean warm pool region (≈70°E–100°E, 5°S–5°N), associated with lower wind speeds and lower sensible heat fluxes. At sub-monthly and Madden–Julian oscillation time scales, correlation of both variables becomes very low. In above frequencies, precipitation positively contributes to the low correlation by dropping Tair considerably while leaving SST without any substantial instant impact. Precipitation is led by positive build up of SST and post-facto drop in it. The strong semi-annual response of SST to mixed layer variability and equatorial waves, with the absence of the same in the Tair, contributes further to the weak correlation at the sub-annual scale. The limited correlation found in the EEIO is mainly related to the annual warming of the region and ENSO which is hard to segregate from the impacts of IOD.

In the present work, a multi response optimization technique based on Taguchi method coupled with grey relational analysis is used for electrical discharge machining operations on duplex (α–β) brass. Stir casting technique was used to fabricate the duplex brass plates. The mechanical properties of the material are reported. Experiments were conducted with three machining variables such as current, pulse-on time and spark voltage and planned as per Taguchi technique. Material removal rate (MRR), electrode wear rate (EWR), and surface roughness (SR) are chosen as output parameters for this study. Results showed that, peak current and spark voltage were the significant parameters to affect MRR, EWR, and SR as per grey relational grade. The optimal combination parameters were identified as A3B3C2 i.e., pulse current at 14 A, pulse on-time at 200 µs, and voltage at 50 V. Analysis of variance was used for analyzing the results. The confirmation tests were performed to validate the results obtained by grey relational analysis and the improvement was achieved.

Aluminum hybrid composites were synthesized using powder metallurgy process from ball milled powders to yield the compositions like: Al+0%TiO2, Al+5%TiO2, Al+5%TiO2+2%Gr and Al+5%TiO2+4%Gr. SEM and EDAX analysis of sintered preforms show the uniform distribution of the reinforcements. Hot upset process was carried out after heating the preforms at 450°C, and the densification and deformation characteristics were studied by correlating the true axial stress with the true axial strain, lateral strain, and theoretical density. Addition of TiO2 to the unreinforced Al and Gr reinforcements to the Al–TiO2 composite increase the induced stresses during hot upset process. The microstructures of hot upset samples are analyzed.

This paper is an attempt to understand the characteristics of Al + TiO2 + Gr hybrid ball-milled composite powders, which would probably have extensive applications in the near future. Aluminum with titanium dioxide (TiO2) and graphite (Gr) powders was ball-milled in order to get a composition like: Al + 0% TiO2, Al + 5% TiO2, Al + 5% TiO2 + 2% Gr, Al + 5% TiO2 + 4% Gr and Al + 5% TiO2 + 6% Gr. The grain size, lattice space, lattice constant, stress, strain, dislocation density, and volume of the unit cell were calculated according to the data of X-Ray diffraction analysis of milled powders. Compressibility tests were performed in a hardened steel die under pressures between 100 to 500 MPa to determine Al with 5 wt.% TiO2 and 2 & 4 wt.% of Gr powder mixtures. For understanding the compaction behavior of aluminum-based hybrid composites reinforced with TiO2 and Gr particles under various applied pressure conditions, the experimental research was realized by using several powder compaction equations. The microstructure analysis is reported for the Al + 5% TiO2 + 6% Gr composite.

The Global Ocean Data Assimilation System configured at Indian National Centre for Ocean Information Services (INCOIS-GODAS) has been forced with satellite-based QuikSCAT gridded winds (QSCAT) to obtain accurate operational ocean analysis, particularly ocean currents, as compared to the default National Centers for Environmental Prediction-Reanalysis 2 (NCEP-R2) wind forcing in the tropical Indian Ocean (TIO). However, after termination of QuikSCAT mission in November 2009, an alternate wind forcing was required for providing operational ocean analysis. The present study examines the suitability of an Advanced Scatterometer (ASCAT)-based daily gridded wind product (DASCAT) for the INCOIS-GODAS. Experiments were performed by forcing INCOIS-GODAS with three different momentum fluxes derived from QSCAT, DASCAT, and NCEP-R2 wind products. Simulated ocean currents from these experiments are validated with respect to in situ current measurements from Research Moored Array for African-Asian-Australian Monsoon Analysis and Prediction (RAMA) buoys. Results suggested that the quality of simulated ocean currents from the daily DASCAT forcing is on par with the QSCAT forcing in the TIO, except for the equatorial Indian Ocean (EIO). Although QSCAT-forced current simulations are slightly better than DASCAT-forced simulations, both QSCAT and DASCAT provide a much better result than NCEP-R2. Our analysis shows that the better simulations of currents over the EIO, with the QSCAT forcing compared to DASCAT forcing, can be attributed to the smoothening of the wind field in the DASCAT compared to QSCAT. The impact of the error in the DASCAT on ocean current analysis is, however, limited to local scales and upper 100 m of water column only. Thus, our study demonstrated that, in the absence of QSCAT, DASCAT is a better alternative for INCOIS-GODAS ocean analysis than the NCEP-R2.

Assimilation methods, meant to constrain divergence of model trajectory from reality using observations, do not exactly satisfy the physical laws governing the model state variables. This allows mismatches in the analysis in the vicinity of observation locations where the effect of assimilation is most prominent. These mismatches are usually mitigated either by the model dynamics in between the analysis cycles and/or by assimilation at the next analysis cycle. However, if the observations coverage is limited in space, as it was in the ocean before the Argo era, these mechanisms may be insufficient to dampen the mismatches, which we call shocks, and they may remain and grow. Here we show through controlled experiments, using real and simulated observations in two different ocean models and assimilation systems, that such shocks are generated in the ocean at the lateral boundaries of the moored buoy network. They thrive and propagate westward as Rossby waves along these boundaries. However, these shocks are essentially eliminated by the assimilation of near-homogenous global Argo distribution. These findings question the fidelity of ocean reanalysis products in the pre-Argo era. For example, a reanalysis that ignores Argo floats and assimilates only moored buoys, wrongly represents 2008 as a negative Indian Ocean Dipole year.

The relationship between ENSO and tropical cyclones (TCs) activity in the Bay of Bengal (BoB) during October–December under cold (1950–1974) and warm (1975–2006) phase of Pacific Decadal Oscillation (PDO) is investigated. A statistically significant difference in the formation of total number of TCs and intense TCs (Category-1 and above) between El Nino and La Nina years is observed when the PDO was in warm phase. Our analysis shows that, there is a tendency to form more number of TCs during La Nina years (2.62 TCs per season) than during El Nino years (1.6 TCs per season) under warm phase of PDO. Moreover, the difference is quite high for intense TCs cases, such as, relatively more number of intense TCs forms in the BoB during La Nina years (1.4 TCs per season) compared to El Nino years (0.10 TCs per season) under warm phase of PDO. However, the difference in the formation of total number of TCs and intense TCs between La Nina and El Nino years is not significant under cold phase of PDO. Significant enhancement in low level cyclonic vorticity and mid-troposphere humidity during La Nina years compared to El Nino years when the PDO was in warm phase, rather than the PDO was in cold phase leads to this difference. Our analysis further shows that how the ENSO related teleconnection to the Indian Ocean region differ under warm and cold phase of PDO.

The near-surface layers in the Arabian Sea progressively warm up from February to early May resulting in the formation of pool of warm waters popularly known as the Arabian Sea Warm Pool (ASWP). The availability of high quality TMI sea surface temperature (SST) data for the years 1998–2010 is exploited to describe the evolution of the ASWP on seasonal and interannual time scales and to explain the associated mechanisms. The multi-year (1998–2010) averaged TMI SSTs during April–May show peak values of the ASWP in excess of 30 °C with its core >30.5 °C extending offshore as a well-marked southwestward tongue stretching from the southwest coast of India. The ASWP shows both seasonal and interannual variability in the evolution of spatio-temporal characteristics such as amplitude, phase and spatial extent. Among these 13 years, the ASWP was most (least) pronounced during 1998, 2003 and 2010 (1999, 2000, 2001 and 2008). The mechanisms that govern the observed interannual variability of the ASWP are examined addressing the most relevant issues such as—(1) dynamic pre-conditioning: background pycnocline topography influenced by the westward propagating Rossby waves during October–May, (2) thermal pre-conditioning: background SST/heat content signal during October–January influenced by the strength of the preceding year’s summer monsoon and the post-monsoon cyclones during October–December, (3) haline pre-conditioning: near-surface vertical salinity stratification during November–February influenced by the advection of low saline waters from the Bay of Bengal, (4) influence of surface net heat flux forcing during February–May, and (5) influence of El Nino/La Nina.

The influence of El Nino/Southern Oscillation (ENSO) and Madden–Julian Oscillation (MJO) and their combined effect on the rapid intensification (RI) of tropical cyclones (TCs) in the Bay of Bengal (BoB) during the primary cyclone season (October–December) is investigated. An empirical index, called genesis potential index (GPI), is used to quantify the relative importance of four environmental parameters responsible for the modulation of TCs characteristics. The analysis shows that TC frequency and RI of TC’s is higher in La Nina than El Nino regime during the primary TC season in the BoB. The combined effect of enhancement (reduction) in mid-tropospheric humidity (primary factor) and relative vorticity (secondary factor) played a major role in the enhancement (reduction) of the TC activity under La Nina (El Nino) regime. In addition, when the MJO is active over the BoB (phases 3–4; characterized by enhanced convective activity in the BoB) under La Nina regime, environmental conditions were more conducive for enhancement of TC activity and RI of TCs compared to corresponding MJO phase under El Nino regime. Increase in mid-tropospheric humidity and reduction in vertical wind shear were identified as the primary and secondary factors enhancing the likelihood of RI of TCs in the BoB during phases 3–4 of MJO under La Nina regime. Further, the role of accumulated tropical cyclone heat potential (ATCHP) on the RI of TC during primary TC season is also investigated. Our analysis demonstrates that ATCHP is large for TCs which undergo RI compared to TCs not undergoing RI.

Upper oceanographic and surface meteorological time-series observations from a moored buoy located at 9.98°N, 88°E in the south-western Bay of Bengal (BoB) were used to quantify variability in upper ocean, forced by a tropical cyclone (TC) Jal during November 2010. Before the passage of TC Jal, salinity and temperature profiles showed a typical BoB post-monsoon structure with relatively warm (30 °C) and low-saline (32.8 psu) waters in the upper 30- to 40-m layer, and relatively cooler and higher salinity (35 psu) waters below. After the passage of cyclone, an abrupt increase of 1 psu (decrease of 1 °C) in salinity (temperature) in the near-surface layers (up to 40-m depth) was observed from buoy measurements, which persisted up to 10–12 days during the relaxation stage of cyclone. Mixed layer heat budget analysis showed that vertical processes are the dominant contributors towards the observed cooling. The net surface heat flux and horizontal advection together contributed approximately 33 % of observed cooling, during TC Jal forced stage. Analysis showed the existence of strong inertial oscillation in the thermocline region and currents with periodicity of ∼2.8 days. During the relaxation stage of the cyclone, upward movement of thermocline in near-inertial frequencies played significant role in mixed layer temperature and salinity variability, by much freer turbulent exchange between the mixed layer and thermocline.

A multifunctional magneto-plasmonic CoFe2O4@Au core-shell nanoparticle was developed by iterative-seeding based method. This nanocargo consists of a cobalt ferrite kernel as a core (Nk) and multiple layers of gold as a functionalizable active stratum, (named as Nk@A after fifth iteration). Nk@A helps in augmenting the physiological stability and enhancing surface plasmon resonance (SPR) property. The targeted delivery of Doxorubicin using Nk@A as a nanopayload is demonstrated in this report. The drug release profile followed first order rate kinetics optimally at pH 5.4, which is considered as an endosomal pH of cells. The cellular MR imaging showed that Nk@A is an efficient T2 contrast agent for both L6 (r2-118.08 mM−1s−1) and Hep2 (r2-217.24 mM−1s−1) cells. Microwave based magnetic hyperthermia studies exhibited an augmentation in the temperature due to the transformation of radiation energy into heat at 2.45 GHz. There was an enhancement in cancer cell cytotoxicity when hyperthermia combined with chemotherapy. Hence, this single nanoplatform can deliver 3-pronged theranostic applications viz., targeted drug-delivery, T2 MR imaging and hyperthermia.

The most used temperature and salinity climatology for the world ocean, including the Indian Ocean, is the World Ocean Atlas (WOA) (Antonov et al 2006, 2010; Locarnini et al 2006, 2010) because of the vast amount of data used in its preparation. The WOA climatology does not, however, include all the available hydrographic data from the Indian Exclusive Economic Zone (EEZ), leading to the potential for improvement if the data from this region are included to prepare a new climatology. We use all the data that went into the preparation of the WOA (Antonov et al 2010; Locarnini et al 2010), but add considerable data from Indian sources, to prepare new annual, seasonal, and monthly climatologies of temperature and salinity for the Indian Ocean. The addition of data improves the climatology considerably in the Indian EEZ, the differences between the new North Indian Ocean Atlas (NIOA) and WOA being most significant in the Bay of Bengal, where the patchiness seen in WOA, an artifact of the sparsity of data, was eliminated in NIOA. The significance of the new climatology is that it presents a more stable climatological value for the temperature and salinity fields in the Indian EEZ.

Turbulent surface heat fluxes (latent and sensible heat) are the two most important parameters through which air–sea interaction takes place at the ocean–atmosphere interface. These fluxes over the global ocean are required to drive ocean models and to validate coupled ocean–atmosphere global models. But because of inadequate in situ observations these are the least understood parameters over the tropical Indian Ocean. Surface heat fluxes also contribute to the oceanic heat budget and control the sea surface temperature in conjunction with upper ocean stratification and ocean currents. The most widely used flux products in diagnostic studies and forcing of ocean general circulation models are the ones provided by the National Centres for Environment Prediction (NCEP) reanalysis. In this study we have compared NCEP reanalysed marine meteorological parameters, which are used for turbulent heat fluxes, with the moored buoy observation in the south-eastern Arabian Sea. The NCEP latent heat flux (LHF) and sensible heat flux (SHF) derived from bulk aerodynamic formula are also compared with that of ship and buoy derived LHF and SHF. The analysis is being carried out during the pre-monsoon and monsoon season of 2005. The analysis shows that NCEP latent as well as sensible heat fluxes are largely underestimated during the monsoon season, however, it is reasonably comparable during the pre-monsoon period. This is largely due to the underestimation of NCEP reanalysis air temperature (AT), wind speed (WS) and relative humidity (RH) compared to buoy observations. The mean differences between buoy and NCEP parameters during the monsoon (pre-monsoon) period are ~21% (~14%) for WS, ~6% (~3%) for RH, and ~0.75% (0.9%) for AT, respectively. The sudden drop in AT during rain events could not be captured by the NCEP data and, hence, large underestimations in SHF. During the pre-monsoon period, major contribution to LHF variations comes from WS, however, both surface winds and relative humidity controls the LHF variations during the monsoon. LHF is mainly determined by WS and RH during the monsoon and, WS is the main contributor during the pre-monsoon.

A three-dimensional model based on the Princeton Ocean Model (POM) has been implemented to study the circulation of the west coast of India. The model uses a curvilinear orthogonal horizontal grid with higher resolution near the coast (3–9 km) and a terrain following sigma coordinate in the vertical. The model is able to simulate Lakshadweep High and Lakshadweep Low (LL) during the winter and summer monsoons, respectively. During winter, the downwelling processes noticed along the coast help in the formation of temperature inversions. The inversions can be seen even up to the depths of ∼50 m, which agrees with the available ARGO data in the region. Model simulations show that coastal upwelling off Kerala is at its peak in July. The intensity of upwelling reduces along the coast towards north. During the existence of LL, there is a cyclonic eddy in the sub-surface waters over the South-Eastern Arabian Sea, with vertical extent up to the depths of 100–150 m and it is strengthened due to the presence of northward counter current in the shelf region. The southerly coastal jet formed along the southern coast as a result of upwelling is noticed a westward shift along with LL. The location of the eddy off Kerala is tilted towards the open ocean with depth and our experiments suggest that this flow can be understood as a first baroclinic mode.

The seasonal variability of sonic layer depth (SLD) in the central Arabian Sea (CAS) (0 to 25°N and 62-66°E) was studied using the temperature and salinity (T/S) profiles from Argo floats for the years 2002–2006. The atmospheric forcing responsible for the observed changes was explored using the meteorological data from NCEP/NCAR and Quickscat winds. SLD was obtained from sound velocity profiles computed from T/S data. Net heat flux and wind forcing regulated SLD in the CAS. Up-welling and down-welling (Ekman dynamics) associated with the Findlater Jet controlled SLD during the summer monsoon. While in winter monsoon, cooling and convective mixing regulated SLD in the study region. Weak winds, high insolation and positive net heat flux lead to the formation of thin, warm and stratified sonic layer during pre and post summer monsoon periods, respectively.

Multi-channel Scanning Microwave Radiometer (MSMR) onboard 1RS P4 (Oceansat I) measured Brightness Temperature data of the different bands are found sensitive to the surface and the overlying atmosphere to different degrees. A judicious combination of multi-channel data can provide such oceanic/atmospheric parameters as surface wind speed, sea surface temperature, water vapour in the marine atmosphere, etc. This paper highlights results obtained in relation to surface wind speed. Co-location and concurrence of several ocean data buoys in the Arabian Sea with MSMR observations allowed empirical construction of D-matrix coefficients for surface wind speed. With both MSMR and the Arabian Sea buoys functioning for the period of one and a half year (June, 1999 to December, 2000) without interruptions provided a large database. All channels are found to exhibit moderate sensitivity to surface wind speed. MSMR data in the immediate vicinity (within 150 km) of the buoy locations and within a time window of one hour were used. A multi-channel linear equation for surface wind speed was subsequently derived. The equation was subjected to tests with independent data set for the period January - June 2001 over the Arabian Sea and found to be moderately accurate. The empirical equation is expected to be useful for regional applications over the Arabian Sea and over regions closer to west coasts, which might have been flagged out in the operational geophysical data stream. An interesting subset of data revealed the wind signatures of the May 2001 cyclone in the Arabian Sea.

In our earlier paper (Bianchi et al. 1997), we concluded that the Sabine-Neches estuary (southeast Texas) had low turnover of autochthonous carbon, based on low light penetrance, short hydraulic residence times (ca. 3 days), high inputs of refractory dissolved organic carbon (DOC), and low inputs of autochthonous carbon sources to sediments. High POC: chlorophyll a ratios (values > 1400) also indicated that allochthonous carbon inputs were a significant source to this light-limited estuary. Annual mean concentrations of chlorophyll a (3.0 ,ug 1-1) and particulate organic carbon (1.1 mg 1-1) in the water column were found to be considerably lower than other shallow estuarine systems. Only during a low inflow period in October 1993, did we observe considerably higher chlorophyll a concentrations in the lower estuary (ca. 16 ,Ig 1-1), which we attributed to injections of coastal waters. Since we did not measure parameters such as bacterial production and biomass as well as dissolved inorganic carbon (DIC), it was clearly not our objective to determine if the Sabine-Neches estuary was net heterotrophic or autotrophic. However, our characterization of the Sabine-Neches as a predominantly net heterotrophic