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Fins from ray-finned fishes do not contain muscles, yet fish can change the shape of their fins with high precision and speed, while producing large hydrodynamic forces without collapsing. This remarkable performance has been intriguing researchers for decades, but experiments have so far focused on homogenized properties, and models were developed only for small deformations and small rotations. Here we present fully instrumented micromechanical tests on individual rays from Rainbow trout in both morphing and flexural deflection mode and at large deflections. We then present a nonlinear mechanical model of the ray that captures the key structural elements controlling the mechanical behavior of rays under large deformations, which we successfully fit onto the experiments for property identification. We found that the flexural stiffness of the mineralized layers in the rays (hemitrichs) is 5-6 times lower than their axial stiffness, an advantageous combination to produce stiff morphing. In addition, the collagenous core region can be modeled with spring elements which are 3-4 orders of magnitude more compliant than the hemitrichs. This fibrillar structure provides negligible resistance to shearing from the initial position, but it prevents buckling and collapse of the structure at large deformations. These insights from the experiments and nonlinear models can serve as new guidelines for the design of efficient bioinspired stiff morphing materials and structures at large deformations. Fins from ray-finned fishes do not contain muscles, yet fish can change the shape of their fins with high precision and speed, while producing large hydrodynamic forces without collapsing. Experiments have so far focused on homogenized properties, and models were developed only for small deformations and small rotations providing limited insight into the rich nonlinear mechanics of natural rays. We present micromechanical tests in both morphing and flexural deflection mode on individual rays, a nonlinear model of the ray that captures the mechanical behavior of rays under large deformations and combine microCT measurements to generate new insights into the nonlinear mechanics of rays. These insights can serve as new guidelines for the design of efficient bioinspired stiff morphing materials and structures at large deformations. [Display omitted] [ABSTRACT FROM AUTHOR]

• A detail study of rain fade at Ka band over tropical region has been done. • Performance comparison of experimental link at 20/30 GHz with ITU-R model done. • "s" parameter relating fade slope to filter characteristics is calculated. Dynamic characteristics of Ka band rain fade (or rain attenuation) over tropical region are relatively less studied, though they are essential for implementation of suitable fade mitigation techniques. In this paper, dynamic characteristics of rain fade at 20 GHz and 30 GHz from GSAT-14 satellite are reported with experimental measurements at Ahmedabad, India. ITU-R model for fade slope probability distribution has been analyzed in this paper and Ka band rain fade has been investigated based on this fade-slope analysis. The ITU-R model is found to closely match 20 GHz measurements, though differences increase at 30 GHz. Fade slopes are found to be within ±0.5 dB/s at both 20 and 30 GHz. Both positive and negative slopes of the fade slope distributions are quasi-similar. ITU-R model's s parameter, relating fade slope to filter characteristics, is found to be very close to the measured value for this region. Distributions of fade slopes are also found to be dependent on the standard deviation values similar to ITU-R recommendation at 20 GHz, but significant deviation is observed at 30 GHz. This observed frequency dependency might be due to increase in cloud attenuation at high frequencies or may be due to limited data set. Results indicate needs of further experimental data at high frequencies from other tropical regions to gain further insight into the fade slope characteristics. This will ultimately help in designing a better prediction model in future. [ABSTRACT FROM AUTHOR]

• Automated detection of solar coronal holes based on fuzzy dual contour model. • Proposed method can handle topological changes as well the presence of vague boundary. • The method outperform existing models in terms of accuracy and computational time. The presence of coronal holes in solar disk plays an important role in influencing the space weather and generation of the solar wind. As such there lies a requirement in proper study and prediction of coronal holes occurs in the solar disk. This, in turn, arises the necessity of detection of coronal holes present in the solar disk. In this work, a Hough transformed inspired fuzzy-energy simulated dual contours-based segmentation technique has been proposed for the detection and extraction of holes in solar disk. In the proposed method Hough transform has been induced to initialize the contour for the contour-based method of segmentation. In the algorithm, two contours (active and static) have been initiated and made to evolve based on the energy function by incorporating the gray-scale intensity. Here in the work one contour is made to deform its shape while the other contour is kept static for the coronal holes detection purpose. The experiment has been carried out on few benchmark datasets and the corresponding outcomes have been compared with the results of other existing algorithms. The comparison results highlight the performance of the proposed technique in detection of coronal holes in solar disk. [ABSTRACT FROM AUTHOR]

• Detailed oxidation study of W-free low density Co base superalloy is presented. • Oxidation is primarily controlled by outward diffusion of Co and Ni. • S/TEM combined with EDS is applied to understand the oxide phase evolution. • A mechanism has been derived from these studies. The paper reports mechanism of high temperature oxidation of the new γ'-strengthened Co-30Ni-10Al-5Mo-2Ta (at%) alloy. The plots of mass gain vs. time show a parabolic growth behaviour at a temperature range of 650–800 °C. The cross-sections of the oxidised samples reveal formation of a complex multilayer of oxides. The top layer comprises of Co 3 O 4 followed by a solid solution of (Co 1-x ,Ni x)O (x varying from 0-0.2). A middle layer evolves with time comprising hexagonal molybdate Co 2 Mo 3 O 8 , metastable TaO and amorphous Al 2 O 3. The γ' dissolve near the interface exposing the γ solid solution with growth of amorphous Al 2 O 3 along the grain boundary. [ABSTRACT FROM AUTHOR]

Quantitative precipitation estimations (QPE) from remote sensing observations requires understanding of the rain characteristics. Rain drop size distribution (DSD) is the fundamental parameter for characterizing rain and depends strongly on the climate, origin and precipitation type. Past studies are mostly concentrated on the DSD variations on locations and rain type, but only a few studies focused on the rain DSD difference between maritime and continental circulation. The aim of the present study is to analyse the different precipitation properties associated with maritime and continental rain at a coastal Indian location. The rain rate probability, DSD parameters, rain rate( R )-radar reflectivity ( Z ) relation and rain attenuation under different rain conditions are presented here based on three years of DSD measurements at Trivandrum (08°52′, 76°93′). Higher value of mean rain rate is observed for maritime rain than continental rain. The Z-R relation is also found to be significantly different for these two types of rain. Abundance of smaller drops is indicated in maritime rain whereas large raindrops has dominance in continental rain. The rain attenuation associated with maritime rain also found to be notably higher than the continental rain. The coefficients for converting the rain rate to attenuation values for different frequencies are estimated for the present location. The results indicate the scope of improvement in QPE by adjusting the Z-R relation from the characteristics difference in rain microstructure/attenuation for continental and maritime rain. [ABSTRACT FROM AUTHOR]

Automatic nowcasting of convective initiation and thunderstorms has potential applications in several sectors including aviation planning and disaster management. In this paper, random forest based machine learning algorithm is tested for nowcasting of convective rain with a ground based radiometer. Brightness temperatures measured at 14 frequencies (7 frequencies in 22–31 GHz band and 7 frequencies in 51–58 GHz bands) are utilized as the inputs of the model. The lower frequency band is associated to the water vapor absorption whereas the upper frequency band relates to the oxygen absorption and hence, provide information on the temperature and humidity of the atmosphere. Synthetic minority over-sampling technique is used to balance the data set and 10-fold cross validation is used to assess the performance of the model. Results indicate that random forest algorithm with fixed alarm generation time of 30 min and 60 min performs quite well (probability of detection of all types of weather condition ∼90%) with low false alarms. It is, however, also observed that reducing the alarm generation time improves the threat score significantly and also decreases false alarms. The proposed model is found to be very sensitive to the boundary layer instability as indicated by the variable importance measure. The study shows the suitability of a random forest algorithm for nowcasting application utilizing a large number of input parameters from diverse sources and can be utilized in other forecasting problems. [ABSTRACT FROM AUTHOR]

This paper investigates the variability of raindrop size distribution (DSD) and rain integral parameters at Ahmedabad, a tropical location, in relation to the radar estimation of rainfall. Rain DSDs for the years 2006–2007 at Ahmedabad (23°04′N, 72°38′E) have been measured using a disdrometer. Variability of DSD is evaluated for different seasons and its effect on the integral rain parameters like radar reflectivity, rainfall intensity and attenuation are examined. A percentage contribution of different drop diameters on rain integral parameters is studied to understand the seasonal behaviour of rain attenuation and radar reflectivity. It is observed that drops with diameter around 3 mm contribute maximum to the radar reflectivity while drops having a diameter around 2 mm contribute the maximum to the rainfall intensity for the present location. The critical diameter range responsible for the maximum contribution in rain attenuation found to shift towards large drops with an increase in rain rate for a fixed frequency. Linear and non-linear regression analysis between radar reflectivity and rainfall intensity show significant variations in different seasons but does not differ much for different regression techniques. Results point to the necessity of considering the seasonal variability of rain DSD in radar remote sensing and will be helpful for better characterizing of rain parameters from radar measurements. [ABSTRACT FROM AUTHOR]

In the present study, the effectiveness of nowcasting convective activities using a microwave radiometer has been examined for Kolkata (22.65° N, 88.45° E), a tropical location. It has been found that the standard deviation of brightness temperature (BT) at 22 GHz and instability indices like Lifting Index (LI), K Index (KI) and Humidity Index (HI) has shown definite changes before convective events. It is also seen that combination of standard deviation of BT at 22 GHz and LI can be most effective in predicting convection. A nowcasting algorithm is prepared using 18 isolated convective events of 2011 and in all cases, a marked variation of these parameters has been seen an hour before the event. Accordingly, a prediction model is developed and tested on convective events of 2012 and 2013. It is seen that the model gives reasonable success in predicting convective rain about 7075 min in advance with a prediction efficiency of 80%. [ABSTRACT FROM AUTHOR]

A priori estimation of delays with error variance of atmospheric radio wave propagation is important for precise position estimation and integrity of the system like Global Positioning System (GPS). Tropospheric effects are less severe than the ionospheric counterpart, but behave in a complex manner, making it difficult to isolate them. In this present paper, a ground based radiometer has been utilized to study the characteristics of tropospheric delay and compared it with the MODIS satellite observations over Kolkata (22.57°N, 88.37°E). Results indicate a good agreement between radiometer and MODIS data except the monsoon months. A climatology of spatial and temporal variation of dry and wet tropospheric delay over the Indian subcontinent have also been estimated using MODIS data and NCEP–NCAR reanalysis data for 2008–2012. The spatial variations of dry delay over Indian region are observed to be in the range of 120–250 cm with limited seasonal variability. However, the wet delay varies from 20 cm in winter months to 45 cm during monsoon period in the coastal and central Indian region. Further analysis reveals that the contribution of wet delays in total delay is significant only along the Indo-Gangetic plain. This indicates that extra precaution is needed in handling tropospheric delay for this region due to fast varying nature of water vapor. [ABSTRACT FROM AUTHOR]

The performances of three instruments namely, Joss–Waldvogel disdrometer, laser precipitation monitor and micro rain radar, are assessed in terms of their ability to measure rain related parameters and to better understand the dependency of measured parameters on the working principles of the instruments. Twenty one rain events of year 2013 pertaining to South-West monsoon are considered for this study. The raindrop size distributions measured by the three instruments show good agreement only for medium sized (1–3 mm) raindrops and for medium rain rates (up to 30 mm/h). However, the mutual agreements are not very good in case of large (> 5 mm) and very small raindrops (< 0.5 mm) as well as for very high rain rates (> 30 mm/h) and very high radar reflectivity factor (> 40 dB). The radar reflectivity–rain rate relation is also studied using linear regression method which shows distinct differences for these instruments, indicating the high sensitivity of Z–R relation on the instrumental measuring principle. [ABSTRACT FROM AUTHOR]

Understanding the interactions between collagen and adhesive mussel foot proteins (mfps) can lead to improved medical and dental adhesives, particularly for collagen-rich tissues. Here we investigated interactions between collagen type-1, the most abundant load-bearing animal protein, and mussel foot protein-3 (mfp-3) using a quartz crystal microbalance and surface forces apparatus (SFA). Both hydrophilic and hydrophobic variants of mfp-3 were exploited to probe the nature of the interaction between the protein and collagen. Our chief findings are: 1) mfp-3 is an effective chaperone for tropocollagen adsorption to TiO 2 and mica surfaces; 2) at pH 3, collagen addition between two mfp-3 films ( W c = 5.4 ± 0.2 mJ/m 2 ) increased their cohesion by nearly 35%; 3) oxidation of Dopa in mfp-3 by periodate did not abolish the adhesion between collagen and mfp-3 films, and 4) collagen bridging between both hydrophilic and hydrophobic mfp-3 variant films is equally robust, suggesting that hydrophobic interactions play a minor role. Extensive H-bonding, π-cation and electrostatic interactions are more plausible to explain the reversible bridging of mfp-3 films by collagen. [ABSTRACT FROM AUTHOR]

Propagation effects on Ku-band over an earth-space path is carried out at Kolkata, India, a tropical location, by receiving a Ku-band signal with horizontal plane polarization transmitted from the geostationary satellite NSS-6 (at 95°E). The amplitude of co-polar attenuation has been monitored along with the measurements of rain rate, rain drop size distribution and height profile of rain rate. The cross-polar enhancement of the signal is also monitored by receiving the same signal in orthogonal direction with another identical receiver. The experimental observations are used to study the effect of melting layer on both co-polar attenuation and cross-polar enhancement for the rain events observed during 2012-2013. Melting layer is indicated by the bright band signature in vertical profile of rain rate. The ground based drop size measurements indicate that the stratiform rain has more number of small drops whereas convective rain composed of large rain drops. The results indicate that the depolarization due to melting layer is more dominant compared to that due to the drop deformation mechanism at low rain rates. [ABSTRACT FROM AUTHOR]

Abstract: Hyaluronic acid (HA) of different molecular weights (M w) was grafted onto mica surfaces to study the effects of M w on the conformation and wear protection properties of a grafted HA (gHA) layer in lubricin (LUB) and bovine synovial fluid (BSF) using a surface forces apparatus. The M w of gHA had significant effects on the wear pressure (P w), at which point the wear initiates. Increasing the gHA M w from 51 to 2590kDa increased P w from 4 to 8MPa in LUB and from 15 to 31MPa in BSF. The 2590kDa gHA in BSF had the best wear protection (P w ∼31MPa), even though it exhibited the highest friction coefficient (μ ∼0.35), indicating that a low μ does not necessarily result in good wear protection, as is often assumed. The normal force profile indicated that BSF confines the gHA structure, making it polymer brush-like, commonly considered as an excellent structure for boundary lubrication. [Copyright &y& Elsevier]

Abstract: The effect of the earth's atmosphere on radio waves propagating over an earth-space path is a major concern in the design and performance of satellite communications systems. Some characteristics of cloud and its effect on signal propagation has been studied using multi-wavelength radiometer at a tropical location of Kolkata, India. The liquid water content profile shows high values at higher altitude during pre-monsoon season indicating the presence of cloud above zero degree isotherm. Significant change in attenuation value is observed for same liquid water content due to change in temperature and accordingly a suitable relationship is obtained for the present location. The measurements indicate that ~4dB and ~12dB attenuation is caused due to cloud at 0.01% outage probability at the Ka and V band, respectively. ITU-R model is found to be overestimating the cloud attenuation over this location and indicate the need for more experimental measurement from tropical region. [Copyright &y& Elsevier]

Abstract: Melting layer height, which is normally assumed to be the limits of rain region, is an important parameter to consider the performance of earth space communication link above 10GHz. In this paper, the variation of melting layer observed by a vertically looking Micro Rain Radar (MRR) for 3years has been presented for two different climatic locations in Indian tropical region — Shillong (25°34′ N, 91°53′ E, 1050m) and Trivandrum (8°29′ N, 76°57′ E, 4m). The analyses show that the variation is quite significant for different months in Shillong but not for Trivandrum. The height of melting layer shows a strong correlation with ground temperature of these locations. The results agree well with the long term Tropical Rainfall Measuring Mission (TRMM) measurements of melting layer indicating suitability of using TRMM data for such study. A comparison of MRR with the nearest Radiosonde measurement indicates that MRR can have potential application in the study of zero degree isotherm height in rainy conditions. Results also clearly indicate that the assumption of constant rain height is not a valid one for all tropical locations. [Copyright &y& Elsevier]

Abstract: The microstructure of rain has been studied with observations using a vertical looking Micro Rain Radar (MRR) at Ahmedabad (23.06°N, 72.62°E), a tropical location in the Indian region. The rain height, derived from the bright band signature of melting layer of radar reflectivity profile, is found to be variable between the heights 4600m and 5200m. The change in the nature of rain, classified on the basis of radar reflectivity, is also observed through the MRR. It has been found that there are three types of rain, namely, convective, mixed and stratiform rain, prevailing with different vertical rain microstructures, such as, Drop Size Distribution (DSD), mean drop size, rain rate, liquid water content and average fall speed of the drops at different heights. It is observed that the vertical DSD profile is more inhomogeneous for mixed and stratiform type rain than for convective type rain. It is also found that the large number of drops of size <0.5mm is present in convective rain whereas in stratiform rain, drops concentration is appreciable up to 1mm. A comparison of measurements taken by ground based Disdrometer and that from the 200m level obtained from MRR shows good agreement for rain rate and DSD at smaller rain rate values. The results may be useful for understanding rain structures over this region. [Copyright &y& Elsevier]

Abstract: Copper(II) forms a complex with sodium 1,4-dihydroxy-9,10-anthraquinone-2-sulphonate (sodium quinizarin-2-sulphonate, NaQSH2), an analogue of the core unit of anthracycline antibiotics used in the treatment of cancer. The 1:2 metal–ligand complex is formed in aqueous solution at neutral and acidic pH while in alkaline pH both 1:1 and 1:2 species are formed. The effective stability constant of the 1:2 metal–ligand complex is 9.64×1016 while that of the 1:1 metal–ligand complex is 9.4×109. The 1:2 complex Cu(NaQSH)2(H2O)2 was synthesized and characterized by different techniques in solid state and in solution. The complex Cu(NaQSH)2(H2O)2 interacts with calf thymus DNA which was studied by fluorescence spectroscopy. The binding constant and site size for the interaction with DNA were determined. [Copyright &y& Elsevier]

The paper reports the influence of Ti on the oxidation behaviour of a new class of low-density L1 2 -strengthened Co-Ni-Al-Ta-Cr-Ti alloys. Oxide scales following the isothermal exposure for 1000 h at 800 °C, 900 °C, and 950 °C were characterized. Contrary to the expectation, increasing Ti content from 2 at% Ti to 4 at% Ti promotes significant oxidation resistance at all temperatures. The varying amount of Ti does not affect the overall sequence of oxide layers and phase chemistry but does affect the kinetics of the barrier layer formation. Two plausible reasons are discussed for the beneficial effect of Ti addition. • Role of Ti on the oxidation behaviour of a low-density Co-Ni-Al-Cr-Ta-Ti superalloy is presented. • Increment from 2 at% to 4 at% Ti improved the resistance at 800 ºC, 900 ºC and 950 ºC. • γ(fcc)-matrix of 4 at% Ti have higher Ni and Al content allowing thick alumina barrier. [ABSTRACT FROM AUTHOR]

Abstract: Ionizing radiation when allowed to fall upon cells or DNA, the radicals produced modify the base-pair region of the double strands. Radiation-induced double-strand modifications in calf thymus DNA were detected using Ni(II) and Fe(III) complexes of 1,2 dihydroxy 9,10 anthraquinone (DHA). 60Co was used as the source for γ-radiation and ethidium bromide (EB) as the fluorescent dye for detecting double-strand modifications caused in DNA. Results show that the Fe(III)–DHA complex is more efficient in modifying the base-pair region in double-stranded DNA in comparison to DHA or the Ni(II)–DHA complex. [Copyright &y& Elsevier]

Lightning is one of the most important extreme weather conditions and is associated with heavy convective rain and thunderstorms. However, the present understanding of such systems as well their effect on precipitation characteristics are insufficient for proper modelling. In this paper, the rain microphysics is studied at Kolkata using an optical disdrometer in relation to the lightning activities. Lightning information is obtained from ground based World Wide Lightning Location Network and Lightning Imaging Sensor onboard International Space Station. The associated cloud features are studied with Doppler weather radar and MODIS satellite measurements. Results indicate significant change in rain microphysics between events with lightning and without lightning. The cloud microphysics indicates that the cloud top temperature is lower and cloud effective droplet size is smaller in case of lightning in comparison to non-lightning situation. On the other hand, large drops are abundant while small drops are less in numbers in rain with lightning than rain without lightning. The a value in Z-R relation is found to be significantly higher for rain with lightning than other type. The rain attenuation is also found to have significant variation under these two conditions. The implication of such varied rain microphysics on GPM Ku and Ka band radar are also reported. • This study focuses on the relation between precipitation microstructure and lightning. • Results indicate significant change of rain microphysical properties between lightning and non-lightning conditions. • Cloud microstructure also seems to vary for the above two rain conditions. • The results are also helpful for improvement of radar retrieval of precipitation for lightning and non-lightning conditions. [ABSTRACT FROM AUTHOR]

Change in microstructural evolution with the addition of Cr. • The role of Cr on the oxidation behavior of Co-Ni-Al-Mo-Ta-Ti class of alloy is presented. • S/TEM combined with EDS is applied to understand the oxide phase evolution. • Cr addition leads to phase transformation of κ-Al 2 O 3 to α-Al 2 O 3. • Increment from 5 at.% to 8 at.% Cr elevated the resistance to cyclic oxidation. The paper reports the role of Cr addition (5 and 8 at.%) on the mechanism of oxidation of γ'-strengthened Co-30Ni-10Al-5Mo-2Ta-2Ti(at.%) alloy at 900 °C. The mass gain curves follow parabolic growth for all the three alloys. Cross-sectional studies reveal the formation of (Co 1-x ,Ni x)O phase as an outermost layer. The intermediate layer consists of complex oxides (Co 2 Mo 3 O 8 , NiO 6 Ta 2 , CoCr 2 O 4 , TiO 2 , Al 2 O 3) of other alloying elements. The formation of spinel CoCr 2 O 4 with the addition of Cr leads to phase transformation of discontinuous κ-Al 2 O 3 to protective and continuous α-Al 2 O 3. Cr containing alloys show the presence of TiN in the γ' free zone. [ABSTRACT FROM AUTHOR]

In this study, we investigated the early nucleation and growth of grain boundary α during the aging heat treatment of Ti-5553. Through a correlative approach using scanning electron microscopy, electron backscatter diffraction, transmission Kikuchi diffraction, transmission electron microscopy, and atom probe tomography, high-angle β-grain boundaries were investigated in detail to understand the evolution of the precipitation of grain boundary α through nucleation and subsequent growth. It is found that at grain boundaries there is a pronounced nucleation of α precipitates with similar orientations. Growth of these similarly orientated α precipitates, in the later stages, leads to their agglomeration and the formation of grain boundary α. This investigation provides insights into the formation of grain boundary α in its early stages of nucleation and growth. [Display omitted] [ABSTRACT FROM AUTHOR]

Increasing lightning fatalities over India is a concerning subject. Especially, it is pretty crucial over North-Eastern part of the country where lightning is extremely frequent. Given the complex nature of the problem, machine learning can be an excellent option in such forecasting scenarios. However, such dynamic processes seek proper transparency of the model. The current work attempts to devise a model for short range prediction (one month ahead) of lightning density based on primary atmospheric parameters from satellite data with a lead time of one month over North –Eastern and Eastern part of the country. Random Forest regression seems to outperform other models explored, with a R2 of 0.86 and an MAE of 0.0071. The interpretation of the model output using SHAP index reveals that 2 m temperature at previous two months and CAPE and K-index at previous month has a positive impact on the output of the model whereas, instantaneous surface heat flux of previous month and two month prior K-index has an inhibiting effect on model's output. The use of machine learning techniques for atmospheric predictions without the shed of the black box can be of importance to the scientific community. Such studies especially over lightning prone tropical regions can be crucial in meteorological forecasting applications. • The study focuses on predicting lightning densities over North Eastern part of India. • It uses machine learning regression for the forecasting. • The study attempts to predicts monthly lightning activities with one month lead time. • The results were interpreted with the help of SHAP index. [ABSTRACT FROM AUTHOR]

This paper emphasizes on NavIC's performance in ionospheric studies over the Indian subcontinent region. The study is performed using data of one year (2017–18) at IIT Indore, a location near the northern crest of Equatorial Ionization Anomaly (EIA). It has been observed that even without the individual error corrections, the results are within ± 20 % of NavIC VTEC estimates observed over the 1° × 1° grid of IPP surrounding the GPS VTEC estimates for most of the time. Additionally, ionospheric response during two distinct geomagnetic storms (September 08 and 28, 2017) at the same location and other IGS stations covering the Indian subcontinent using both GPS and NavIC has also been presented. This analysis revealed similar variations in TEC during the geomagnetic storms of September 2017, indicating the suitability of NavIC to study space weather events along with the ionospheric studies over the Indian subcontinent. [ABSTRACT FROM AUTHOR]

[Display omitted] • Elastic properties of a Zr-based bulk metallic glass were probed by spatially resolved nanoindentation. • An elastic microstructure is observed with fluctuations at a decorrelation length scale of 170 nm. • Spatially resolved compositional analysis excludes chemical modulations to generate the elastic fluctuations. • The elastic length scale is connected to local density fluctuations that emerge due to cooling constraints during casting. • The emerging elastic length scale suggests the formulation of a structure–property relationship for bulk metallic glasses. Metallic glasses (MGs) are known to be structurally heterogeneous at the nanometer (nm) scale. In addition, elastic property mapping has indicated the presence of at least an order-of-magnitude larger length scales, of which the origin continues to remain unknown. Here we demonstrate the existence of an elastic decorrelation length of the order of 100 nm in a Zr-based bulk MG using spatially resolved elastic property mapping via nanoindentation. Since compositional modulations, sufficiently large to account for this elastic microstructure, were not resolved by analytical scanning-transmission electron microscopy, chemical phase separation such as spinodal decomposition cannot explain their presence. Instead, we argue that the revealed long-range elastic modulations stem from structural variations affecting the local density. These emerge during solidification and are strongly influenced by the cooling constraints imposed on bulk MGs during the casting process. [ABSTRACT FROM AUTHOR]

Two new copper(II) complexes, [Cu(L)(OCN)] (1) and [CuL(dca)]n (2), where HL = 2-(-(2-(diethylamino)ethylimino)methyl)naphthalen-1-ol, dca = N(CN)2-, have been synthesized and characterized by elemental analysis, IR, UV-VIS spectroscopy and single crystal X-ray diffraction studies. Complex 1 has square planar and complex 2 square pyramidal geometries in solid state around metal centre. Interactions of the complexes with calf thymus DNA (CT DNA) were studied by UV-VIS spectroscopy. Binding constant and site size of interaction were determined. Binding site size and intrinsic binding constant K revealed complex 1 interacted with calf thymus DNA better than complex 2. [CuL(dca)]n (2), where HL = 2-(-(2-(diethylamino)ethylimino)methyl)naphthalen-1-ol, dca = N(CN)2-, have been synthesized and characterized by elemental analysis, IR, UV-VIS spectroscopy and single crystal X-ray diffraction studies. Complex 1 has square planar and complex 2 square pyramidal geometries in solid state around metal centre. Interactions of the complexes with calf thymus DNA (CT DNA) were studied by UV-VIS spectroscopy. Binding constant and site size of interaction were determined. Binding site size and intrinsic binding constant K revealed complex 1 interacted with calf thymus DNA better than complex 2. [ABSTRACT FROM AUTHOR]

Abstract: Radiation-induced double-strand modification of DNA was studied in the absence and presence of sodium 1,4-dihydroxy-9,10-anthraquinone-2-sulfonate (NaQSH2) and its metal (Cu2+ and Ni2+) complexes in aerated, de-aerated (Argon saturated) and N2O saturated aqueous media at pH 7.4. Ethidium bromide, an established DNA intercalator was used to estimate DNA remaining after interaction with γ-radiation, by measuring loss of fluorescence of the ethidium bromide–DNA adduct. In de-aerated (Argon saturated) and N2O saturated aqueous media radiation-induced double-strand modification of calf thymus DNA was comparatively less in presence of NaQSH2 and its Ni(II) complex than standard control indicating the compounds behaved as radio-protectors. However, in presence of the Cu(II) complex radiation-induced double-strand modification increased significantly. In N2O saturated medium, double-strand modification of DNA was almost double in all cases than that observed in de-aerated (Argon saturated) medium indicating OH radicals played a major role in modifying DNA. That OH radicals were important was verified by repeating experiments using tertiary-butanol that showed significant decrease in DNA modification. Another important observation was in aerated medium NaQSH2, Ni(II)–NaQSH2 did not show radioprotection while Cu(II)–NaQSH2 was an almost equally effective radiosensitizer as that observed in N2O saturated medium. Role of molecular oxygen as radiosensitizer was thus realized. [Copyright &y& Elsevier]

Quinalizarin, an analogue of anthracycline anticancer agents, is an anticancer agent itself. A CuII complex was prepared and characterized by elemental analysis, UV-Vis & IR spectroscopy, mass spectrometry, EPR and DFT. The intention behind the preparation of the complex was to increase cellular uptake, compare its binding with DNA against that of quinalizarin, modulation of semiquinone formation, realization of human DNA topoisomerase I & human DNA topoisomerase II inhibition and observation of anticancer activity. While the first two attributes of complex formation lead to increased efficacy, decrease in semiquinone generation could results in a compromise with efficacy. Inhibition of human DNA topoisomerase makes up this envisaged compromise in free radical activity since the complex shows remarkable ability to disrupt activities of human DNA topoisomerase I and II. The complex unlike quinalizarin, does not catalyze flow of electrons from NADH to O 2 to the extent known for quinalizarin. Hence, decrease in semiquinone or superoxide radical anion could make modified quinalizarin [as CuII complex] less efficient in free radical pathway. However, it would be less cardiotoxic and that would be advantageous to qualify it as a better anticancer agent. Although binding to calf thymus DNA was comparable to quinalizarin, it was weaker than anthracyclines. Low cost of quinalizarin could justify consideration as a substitute for anthracyclines but the study revealed IC 50 of quinalizarin/CuII-quinalizarin was much higher than anthracyclines or their complexes. Even then, there is a possibility that CuII-quinalizarin could be an improved and less costly form of quinalizarin as anticancer agent. Synopsis: A CuII complex of quinalizarin was prepared with the intention of increasing cellular uptake, study binding with DNA, modulate formation of semiquinone and check for inhibition of human DNA topoisomerase I and II to correlate observed anticancer activity. Low cost of quinalizarin justifies its consideration as a substitute for anthracyclines. [Display omitted] • Quinalizarin (THAQ), an analogue of anthracyclines, is active pharmacologically. • Complex formation modulates generation of free radicals that affect its mechanism of action. • The complex is an efficient inhibitor of topoisomerase enzymes, crucial for drug action. • Interaction of [CuII(THAQ) 2 (H 2 O) 2 ] with topoisomerase was realized by molecular docking. • THAQ, the acetylated form, shows more efficacy on ALL MOLT 4 cells than [CuII(THAQ) 2 (H 2 O) 2 ]. [ABSTRACT FROM AUTHOR]

Abstract: Cytotoxic studies using an azo compound HPAN and its Co(II) complex were carried out on non-small lung epithelium carcinoma (A549) cells and peripheral blood mononuclear (PBM) cells. The results obtained suggest that the Co(II) complex is much less toxic toward both cell lines and the decreased toxicity due to the complex was more pronounced with carcinoma A549 cells. An attempt was made to correlate the findings related to cytotoxicity with the interaction of the compounds with DNA using calf thymus DNA as the target. The study was able to conclude that the complex was a relatively weak binder to calf thymus DNA. This information was used to explain the interaction of azo compounds with DNA in peripheral blood mononuclear cells and A549 lung carcinoma cells. It was concluded that the Co(II) complex interacts with DNA to a much lesser extent than HPAN alone. Cyclic voltammetry experiments carried out with HPAN and the Co(II) complex further showed that the presence of the metal ion in the complex prevents reduction of the azo group to such species that are responsible for inducing cytotoxicity. The overall finding was that complex formation with azo compounds might serve as a possible route to curb their toxicities. [Copyright &y& Elsevier]

Curcumin is a tantalizing molecule with multifaceted therapeutic potentials. However, its therapeutic applications are severely hampered because of poor bioavailability, attributed to its instability and aqueous insolubility. In an attempt to overcome this inherent limitation and develop curcumin-based antibacterials, we had earlier synthesized and characterized a metal complex of Cu(II) with curcumin, having the formula [Cu(Curcumin)(OCOCH 3)(H 2 O)], hereafter referred to as Cu(Cur). In this study, the complex, i.e., Cu(Cur), was investigated for its stability and antibacterial activity along with its possible mechanism of action in comparison to the parent molecule, curcumin. Complex formation resulted in improved stability as Cu(Cur) was found to be highly stable under different physiological conditions. Such improved stability was verified with the help of UV–Vis spectroscopy and HPLC. With improved stability, Cu(Cur) exhibited potent and significantly enhanced activity over curcumin against both E. coli and S. aureus. Calcein leakage assay revealed that the complex triggered immediate membrane permeabilization in S. aureus. This membrane disruptive mode of action was further corroborated by microscopic visualization. The excellent potency of the complex was augmented by its safe toxicological profile as it was non-hemolytic and non-cytotoxic towards mammalian cells, making it a suitable candidate for in vivo investigations. Altogether, this investigation is a critical appraisal that advocates the antibacterial potential of this stable, membrane-targeting and non-toxic complex, thereby presenting new perspectives for its therapeutic application against bacterial infections. The synthesized complex of curcumin and Cu(II), which is referred to as Cu(Cur), kills both Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria by rapturing bacterial cell membrane. [Display omitted] • The Cu curcumin complex, Cu(Cur), was highly stable at physiological pH, unlike curcumin. • Cu(Cur) was active against both Gram-positive and Gram-negative bacterial strains. • Cu(Cur) showed significant improvement in antibacterial efficacy compared to curcumin. • The complex exhibited bacterial membrane targeting mechanism of action. • Like curcumin, the complex was also non-toxic to the mammalian cells. [ABSTRACT FROM AUTHOR]