We analysed the multiband optical behaviour of the BL Lacertae object, S5 0716+714, during its outburst state from 2014 November to 2015 March. We took data on 23 nights at three observatories, one ...in India and two in Bulgaria, making quasi-simultaneous observations in B, V, R, and I bands. We measured multiband optical fluxes, colour, and spectral variations for this blazar on intraday and short time-scales. The source was in a flaring state during the period analysed and displayed intense variability in all wavelengths. R-band magnitude of 11.6 was attained by the target on 2015 January 18, which is the brightest value ever recorded for S5 0716+714. The discrete correlation function method yielded good correlation between the bands with no measurable time lags, implying that radiation in these bands originate from the same region and by the same mechanism. We also used the structure function technique to look for characteristic time-scales in the light curves. During the times of rapid variability, no evidence for the source to display spectral changes with magnitude was found on either of the time-scales. The amplitude of variations tends to increase with increasing frequency with a maximum of ∼22 per cent seen during flaring states in B band. A mild trend of larger variability amplitude as the source brightens was also found. We found the duty cycle of our source during the analysed period to be ∼90 per cent. We also investigated the optical spectral energy distribution of S5 0716+714 using B, V, R, and I data points for 21 nights. We briefly discuss physical mechanisms most likely responsible for its flux and spectral variations.
SARS-CoV-2 virus and other pathogenic microbes are transmitted to the environment through contacting surfaces, which need to be sterilized for the prevention of COVID-19 and related diseases. In this ...study, a prototype of a cost-effective sterilization box is developed to disinfect small items. The box utilizes ultra violet (UV) radiation with heat. For performance assessment, two studies were performed. First, IgG (glycoprotein, a model protein similar to that of spike glycoprotein of SARS-COV-2) was incubated under UV and heat sterilization. An incubation with UV at 70 °C for 15 min was found to be effective in unfolding and aggregation of the protein. At optimized condition, the hydrodynamic size of the protein increased to ~171 nm from ~5 nm of the native protein. Similarly, the OD280 values also increased from 0.17 to 0.78 indicating the exposure of more aromatic moieties and unfolding of the protein. The unfolding and aggregation of the protein were further confirmed by the intrinsic fluorescence measurement and FTIR studies, showing a 70% increase in the β-sheets and a 22% decrease in the α-helixes of the protein. The designed box was effective in damaging the protein's native structure indicating the effective inactivation of the SARS-COV-2. Furthermore, the incubation at 70 °C for 15 min inside the chamber resulted in 100% antibacterial efficacy for the clinically relevant E.coli bacteria as well as for bacteria collected from daily use items. It is the first detailed performance study on the efficacy of using UV irradiation and heat together for disinfection from virus and bacteria.
•A combine heat and UV radiation based sterilization box (prototype) is developed.•Incubation with UV at 70 °C for 15 min can inactivate virus and bacteria.•Combined use of UV and heat is more effective than their individual uses.•Designed sterilization box effectively sterilized the surfaces of daily use items.
Ultrasonic-assisted magnetic abrasive finishing (UAMAF) is an advanced abrasive finishing process that finishes a workpiece surface effectually when compared to a traditional magnetic abrasive ...finishing process in the order of nanometer. A change of surface roughness and material removal rate are two important factors determining the efficacy of the process. These two factors affect the surface quality and production time and, thereby, a total production cost. The finishing performed at higher material removal rates leads to a loss in shape/form accuracy of the surface. At the same time, increasing the rate of change of surface roughness increases loss of material. For an optimized finishing process, a compromise has to be made between the change of surface roughness and the material removal (loss). In this work, a multi-objective optimization technique based on genetic algorithm is used to optimize the finishing parameters in the UAMAF processes. A fuzzy-set-based strategy for a higher level decision is also discussed. The results of the optimization based on a mathematical model of the process are validated with the experimental results and are found to be in compliance.
To search for optical variability on a wide range of time-scales, we have carried out photometric monitoring of two flat spectrum radio quasars, 3C 454.3 and 3C 279, plus one BL Lac, S5 0716+714, all ...of which have been exhibiting remarkably high activity and pronounced variability at all wavelengths. CCD magnitudes in B, V, R, and I passbands were determined for ∼7000 new optical observations from 114 nights made during 2011–2014, with an average length of ∼4 h each, at seven optical telescopes: four in Bulgaria, one in Greece, and two in India. We measured multiband optical flux and colour variations on diverse time-scales. Discrete correlation functions were computed among B, V, R, and I observations, to search for any time delays. We found weak correlations in some cases with no significant time lags. The structure function method was used to estimate any characteristic time-scales of variability. We also investigated the spectral energy distribution of the three blazars using B, V, R, I, J, and K passband data. We found that the sources almost always follow a bluer-when-brighter trend. We discuss possible physical causes of the observed spectral variability.
This paper presents the electrical performance and construction details of the S-band dual transmit/ receive module (DTRM) over 400 MHz bandwidth for an active phased array radar. Each T/R channel of ...DTRM delivers > 120W peak power with ≥ 38% module efficiency. The T/R module operates up to one milli-sec pulse width and < 20% duty cycle. The T/R module has ≃ 30±2 dB receive gain and exhibits < 3.5 dB noise figure over 400 MHz bandwidth and −10°C to +55°C temperature range. It is designed for a high dynamic range with good sensitivity and exhibits > +4dBm P1dB point and has > +22 dBm OIP3. Each T/R channel is designed in common leg architecture with a 6-bit digital phase shifter, 6-bit digital attenuator, and a single-pole double-throw (SPDT) switch to reduce the monolithic microwave integrated circuits (MMICs) count and cost of the T/R module. The DTRM is realized in an Aluminium 6061-T6 casing and mounted on a heat exchanger for efficient thermal management. The DTRM has a 26-pin D-type high-density (HD) connector and blind-mate adapter (BMA) for the RF interface. It is realized with the physical dimension of ≃ 175.0 mm(L) x 80.0 mm(W) x 26.0 mm (H) (mm) and has < 0.6 Kg weight for modern active phased arrays.
Optical flux and spectral variability of blazars Gaur, Haritma; Gupta, Alok C.; Strigachev, A. ...
Monthly notices of the Royal Astronomical Society,
1 October 2012, 20121001, Volume:
425, Issue:
4
Journal Article
Peer reviewed
Open access
ABSTRACT
We report the results of optical monitoring for a sample of 11 blazars including 10 BL Lacertae objects (BL Lacs) and one flat spectrum radio quasar (FSRQ). We have measured the multiband ...optical flux and colour variations in these blazars on intraday and short‐term time‐scales of months and have limited data for two more blazars. These photometric observations were made during 2009–2011, using six optical telescopes, four in Bulgaria, one in Greece and one in India. On short‐term time‐scales we found significant flux variations in nine of the sources and colour variations in three of them. Intraday variability was detected on six nights for two sources out of the 18 nights and four sources for which we collected such data. These new optical observations of these blazars plus data from our previous published papers (for three more blazars) were used to analyse their spectral flux distributions in the optical frequency range. Our full sample for this purpose includes six high‐synchrotron‐frequency‐peaked BL Lacs (HSPs), three intermediate‐synchrotron‐frequency‐peaked BL Lacs (ISPs) and six low‐synchrotron‐frequency‐peaked BL Lacs (LSPs; including both BL Lacs and FSRQs). We also investigated the spectral slope variability and found that the average spectral slopes of LSPs show a good accordance with the synchrotron self‐Compton loss dominated model. Our analysis supports previous studies that found that the spectra of the HSPs and FSRQs have significant additional emission components. The spectra of all these HSPs and LSPs get flatter when they become brighter, while for FSRQs the opposite appears to hold. This supports the hypothesis that there is a significant thermal contribution to the optical spectrum for FSRQs.
Biomass feedstock having less competition with food crops are desirable for bio-ethanol production and such resources may not be localized geographically. A distributed production strategy is ...therefore more suitable for feedstock like water hyacinth with a decentralized availability. In this study, we have demonstrated the suitability of this feedstock for production of fermentable sugars using cellulases produced on site. Testing of acid and alkali pretreatment methods indicated that alkali pretreatment was more efficient in making the sample susceptible to enzyme hydrolysis. Cellulase and β-glucosidase loading and the effect of surfactants were studied and optimized to improve saccharification. Redesigning of enzyme blends resulted in an improvement of saccharification from 57% to 71%. A crude trial on fermentation of the enzymatic hydrolysate using the common baker’s yeast
Saccharomyces cerevisiae yielded an ethanol concentration of 4.4
g/L.
In this paper, we have used optical intra-day variability archive data to calculate the central black hole masses and Eddington luminosities for nine blazars: 3C 66A, AO 0235+164, S5 0716+714, PKS ...0735+178, OJ 287, 1215+303, 1216−010, 1308+326, PKS 1510−089, Mrk 501 and BL Lac using intra-day variability timescales and periodicity (if present). The calculated central black hole mass of these nine blazars using intra-day variability timescales are found to be in the range of 1.22–25.30
×
10
7
M
⊙ and corresponding Eddington luminosity in the range of 1.58–32.88
×
10
45
erg
s
−1. The black hole mass and Eddington luminosity are in the range of 0.32–31.23
×
10
8
M
⊙ and 1.23–31.20
×
10
46
erg
s
−1, respectively when optical Doppler factor is taken into account. The comparison show, our estimated values of black hole mass are consistent with earlier reported values. Periodicity were present in two blazars OJ 287 and 1216−010 which give the central black hole mass of these blazars in the range of 1.32–14.6
×
10
7
M
⊙ and corresponding Eddington luminosity in the range of 1.60–19.0
×
10
45
erg
s
−1, respectively.
•We study radial density structure of three young open clusters using King profile.•We determine their initial mass function and luminosity function.•Mass function (MF) slopes of these clusters are ...in agreement with Salpeter value.•Spatial variation of MF slopes indicates mass segregation.•We find that these clusters are dynamically relaxed.
Using UBVRI CCD data taken from 104-cm Sampurnanand Telescope, ARIES, Nainital, we present the structure, initial mass function and mass segregation of three young age (∼10Myr) open star clusters: NGC 2129, NGC 1502 and King 12. Based on photometric as well as astrometric criteria, the cluster member stars as well as field stars have been identified. We construct luminosity function which is further used to estimate the mass functions by employing theoretical stellar evolutionary isochrones. The entire cluster region mass function (MF) slopes for NGC 2129, NGC 1502 and King 12 are obtained as −2.55±0.14, −2.73±0.36 and −1.94±0.12 respectively. It is found that changes in the MF slope of King 12 are significantly different compared to NGC 2129 and NGC 1502 from inner region to outer region. The MF slope for King 12 is steeper at larger radii. The dynamical relaxation times for all three clusters are found to be less than age of the clusters. This indicates that all these clusters are dynamically relaxed. We show that for NGC 1502 and King 12, passing off of low mass stars from the inner region of the clusters to the halo occurs during the course of evolution.
The solid–liquid phase equilibrium data on three binary organic systems, namely 4-hydroxy benzaldehyde (HB)–2-methyl-4-nitro aniline (MNA), 3-hydroxy-4-methoxybenzaldehyde ...(HMB)–2-chloro-4-nitroaniline (CNA) and 4-aminobenzophenone (ABP)–
m
-nitrobenzoic acid (NBA), determined by the thaw-melt method, show the formation of a eutectic at 0.60 mol fraction of HB, 0.48 mol fraction of HMB and 0.51 mol fraction of ABP. These systems are organic analogue of nonmetal–nonmetal system. The values of enthalpy of fusion of eutectics and parent components were determined by the DSC method. Using the heat of fusion values, entropy of fusion, heat of mixing, excess thermodynamic functions and Jackson’s roughness parameter were calculated. The negative values of enthalpy of mixing in each case suggest the associative interaction between the molecules of the eutectic melt. The positive value of excess free energy for HB–MNA system indicates the associative interaction between like molecules, while the negative values of excess free energy for HMB–CNA and ABP–NBA indicate the associative interaction between unlike molecules.
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