Search

Citrullus colocynthis (L.) Schard (Cucurbitaceae) is an endangered medicinal herb. It contains glycosides, cucurbitacins (colocynthin and colocynthetin), cucurbitacins A, B, C, D, E, I, J, K and L which are having medicinal values in various parts of the plant. Cucurbitacin E, a highly oxidated steroid consisting of a tetracyclic triterpene which is more potential triterpenoid for anti-cancer. In this study, we made an attempt to investigate the effect of elicitors with methyl jasmonate (MeJA), salicylic acid (SA), precursors like squalene and mevalonic acid as abiotic elicitors. Precursors were used for enhancement production of cucurbitacin E through cell suspension culture and in vitro plant cultures of Citrullus colocynthis. Based on HPLC results, MeJA is better elicitor than SA and in precursors squalene is better than mevalonic acid for cucurbitacin E production from Citrullus colocynthis cell suspension and in vitro plant cultures. Among all the concentration of elicitors MeJA, SA and precursors squalene, mevalonic acid, 75 µM concentrations have shown best results and MeJA showed highest peak area of 17.97 with 8.63 fold in cell suspension culture. Whereas, the effect of elicitor and precursor feeding studies in in vitro plant culture have produced high amount of cucurbitacin E at 100 µM concentration. Hence, the protocol established in the present study provides an opportunity for enhancement of biological active (anticancer) compound cucurbitacin E.

Muntingia calabura L. is a potent medicinal plant. Because of that several researchers reported phytochemical and pharmacological studies, but only minimal information is obtainable on tissue culture and genetic stability evaluation studies. Therefore, in the present investigation we attempted to establish a reliable direct and indirect regeneration study through leaf and node explants on MS medium containing cytokinins BAP and KN (0.5-3.0 mg l-1) in combination with auxins IAA and NAA (0.5 mg l-1). The breakage of bud and shoot initiation were noticed with the initiation of callus at lower concentrations of auxin alone at 0.5 mg l-1. 2,4-D was found to be good in callus induction from leaf and nodal explants. A problem of browning callus was prevented by regular subculturing of callus cultures. Leaf explants exhibited maximum number of shoots (32±0.88a) with shoot length (7.6±0.17a) and nodal explants obtained optimal number of shoots (26±0.88a) with shoot length (9.6±0.30a) on MS medium supplemented with BAP (2 mg l-1) and IAA (0.5 mg l-1). Half strength MS medium fortified with IBA (2.0 mg l-1) was effective and achieved 70% of rooting. These well-developed plantlets were shifted to pots containing soil and vermicompost in 1:1 ratio for acclimatization. The acclimatized plants were field transferred with survival rate of 85%. The ISSR and RAPD markers analysis revealed the genetic stability of in vitro regenerated plants with the mother plant.

This paper presents a half power divider operating at Ku-band which is designed using concept of Empty SIW. For easy connectivity with other planar microwave devices and circuits, the micro strip line to HSIW transition was implemented, with section of ESIW expanded at discontinuity interface, to reduce radiation and leakage effects and provide impedance matching. An ESIW based, half power divider is fabricated on RT/duroid 5880 and measured in range of 11.5 GHz to 18.5 GHz. This power divider provided a return loss of at least 12 dB, an insertion loss of 0.5 ± 0.03 dB, and also when used as Power combiner, its power combining efficiency is observed as 89.4% from 12–16.5GHz.

A wide band antenna gain enhancement using metamaterial concept is presented. A CPW fed wide band antenna has been designed at operating frequencies 2.6-4.2GHZ. Artificial material properties are obtained by designing a metamaterial unit cell at operating frequencies. The dielectric properties of the substrate are dominated by metamaterial unit cell arrangement underneath of the antenna. The proposed antenna is modelled in CST MW STUDIO. 2.5dB gain improvement is achieved by arranging metasurface underneath of the antenna without effecting the operating frequencies.

this paper presents modelling of high gain metal package, which is suitable for packaging of GaAs monolithic microwave integrated circuit working upto 31.228GHz and high gain. This 8mmX6mmX2.5mm package houses 6-RF ports, 6-DC ports, microstrip lines and optimized wire bonding interconnects. This package is 3D EM simulated using a CST microwave studio. The modelled package is fabricated using brass material. This package can be used as a 40dB gain block amplifier, MCM, High isolation switches, transmitter chain upto 40dB gain and can be used as a receiver chain because of its high gain accommodation capability over the broadband frequency range. The fabricated package contains 50-ohm transmission lines fabricated with the thin film technology and input output RF connector working in broadband frequency range upto 40GHz and DC connectors. All ports S-parameters S11, S12, S21 and S22 are recorded and compared with offset ports s-parameters. Port selection analysis carried out in three configurations whereas offset port selection as shown 10 dB improvement in isolation compared to straight ports selection.

this paper details a multi-chip module (MCM) suitable for GaAs monolithic microwave integrated circuit common control high gain block MCM package design, 3D EM simulation of the package, package fabrication and end module level execution, which includes assembly and testing under various environmental test conditions as per the space standards. This MCM package designed using three internally separated cavities for individual cavity isolation, 4-RF Ports, 10mil thin film microstrip line and optimized wire bonding interconnects, and the same package is EM simulated using a CST microwave studio. This package modelled and fabricated using kovar material. This MCM package proposed to house a chain of four amplifiers with a common gain of 69dB, 2 SPDT switches with insertion loss of 3.6dB, a digital attenuator with initial attenuation of 2.5dB with TTL driver and 2 thermopads of 3dB individual attenuation. This package resonating frequency is 7.484GHz. The packaged MCM measurements are carried out over a frequency of 1.1GHz-1.4GHz and resulted with S21 of 60dB, S11&S22 of better than 15dB and P1dB out of 15dBm.

In this paper design of ceramic package and modelling of the package to meet the demands of low-cost and lower parasitic interconnect technology for wideband is presented. This proposed package suitability for high gain GaAs MMIC packaging in wideband frequency range with lower parasitic effects on MMIC performance is also presented. It is a 7 × 7 ceramic package with 48-pins. This proposed structure is embedded with GaAs MMICs working before the resonance frequency of the packaging. For proper grounding the package base is metal selected with sufficient number of filled via holes. The package base metal and the package pins are gold plated to suit for die bonding and also for wire bonding. This package pins are with 0.3 mm width and 0.2 mm spacing between the pins distributed four sides equally without leads. This no leads pin packaging structure gives very good benefits at microwave frequency due to lower inductance and higher isolation between pins. This package structure also shows with lower electromagnetic interference and electromagnetic coupling between pins and die. For MMICs functionality test a separate test structure is designed for RF lines and DC lines and fabricated on FR4 substrate with properly modelled transmission lines at input and output. This proposed package is EM simulated in CST microwave studio. The fabricated ceramic package contains 50 ohm lines fabricated with the thin film technology as well as IO RF connector working in wideband frequency range and their corresponding S11, S22, S21 and NF are recorded. This package resulted with typical S21 of 23 dB, S11 and S22 of better than 10 dB and typical NF of 2.5 dB which are in line with MMIC simulation data. Gain flatness over the frequency is less than ± 0.3 dB and a NF of less than ± 0.05.

Heat shock factors regulate responses to high temperature, salinity, water deprivation, or heavy metals. Their function in combinations of stresses is, however, not known. Arabidopsis HEAT SHOCK FACTOR A4A (HSFA4A) was previously reported to regulate responses to salt and oxidative stresses. Here we show, that the HSFA4A gene is induced by salt, elevated temperature, and a combination of these conditions. Fast translocation of HSFA4A tagged with yellow fluorescent protein from cytosol to nuclei takes place in salt-treated cells. HSFA4A can be phosphorylated not only by mitogen-activated protein (MAP) kinases MPK3 and MPK6 but also by MPK4, and Ser309 is the dominant MAP kinase phosphorylation site. In vivo data suggest that HSFA4A can be the substrate of other kinases as well. Changing Ser309 to Asp or Ala alters intramolecular multimerization. Chromatin immunoprecipitation assays confirmed binding of HSFA4A to promoters of target genes encoding the small heat shock protein HSP17.6A and transcription factors WRKY30 and ZAT12. HSFA4A overexpression enhanced tolerance to individually and simultaneously applied heat and salt stresses through reduction of oxidative damage. Our results suggest that this heat shock factor is a component of a complex stress regulatory pathway, connecting upstream signals mediated by MAP kinases MPK3/6 and MPK4 with transcription regulation of a set of stress-induced target genes., Heat shock factor A4A is phosphorylated by MPK4; it directly binds to promoters of various chaperon and transcription factor genes and controls responses to combined salt and heat stresses.