mW Power (mw + power)

Distribution by Scientific Domains

Selected Abstracts

Improving Grape Quality Using Microwave Vacuum Drying Associated with Temperature Control

C. D. Clary
ABSTRACT:, Microwave (MW) vacuum dehydration using temperature to control the level of MW power demonstrated potential in improving the performance of the process. Product surface temperature measured by an infrared temperature sensor was used to control MW power at any level between 0 and 3 kW. Multiple linear regression analysis indicated an r2= 0.942 for prediction of final moisture content and r2= 0.985 for prediction of puffed character of grapes based on product temperature, time, specific energy, fresh fruit sugar, and fresh fruit moisture content. Temperature was found to be the most significant predictor. The elemental and compound contents of grapes dried using MW vacuum was compared to sun-dried raisins. The grapes dried using MW vacuum exhibited better preservation. Vitamin A was found in the MW-vacuum-dried grapes but none was detected in the raisins, and Vitamin C, thiamine, and riboflavin were also higher in the MW-vacuum-dried grapes than in the raisins. [source]

Synthesis of graft copolymers of xyloglucan and acrylonitrile

Anuradha Mishra
Abstract Xyloglucan (XG), a water-soluble food grade polysaccharide is reported as a substrate for the graft copolymerization of acrylonitrile (AN). XG was extracted from tamarind seed mucilage. Polymerization was initiated both by ceric ion in aqueous medium under N2 atmosphere and with microwave (MW) irradiation. The progress of the reaction was monitored gravimetrically. The effect of different reaction parameters such as monomer concentration, level of ceric ammonium nitrate/HNO3 (CAN) initiator, reaction time and temperature, and MW power on the percent grafting (PG) was studied. Grafting of polyacrylonitrile (PAN) onto XG was confirmed by Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and scanning electron microscope (SEM) techniques have been used to study the thermal and morphological changes in the materials. Copyright 2007 John Wiley & Sons, Ltd. [source]

Microwave-Assisted Functionalization of Carbon Nanostructures in Ionic Liquids

Ivan Guryanov Dr.
Abstract The effect of microwave (MW) irradiation and ionic liquids (IL) on the cycloaddition of azomethine ylides to [60]fullerene has been investigated by screening the reaction protocol with regard to the IL medium composition, the applied MW power, and the simultaneous cooling of the system. [60]Fullerene conversion up to 98,% is achieved in 2,10,min, by using a 1:3 mixture of the IL 1-methyl-3- n -octyl imidazolium tetrafluoroborate ([omim]BF4) and o -dichlorobenzene, and an applied power as low as 12,W. The mono- versus poly-addition selectivity to [60]fullerene can be tuned as a function of fullerene concentration. The reaction scope includes aliphatic, aromatic, and fluorous-tagged (FT) derivatives. MW irradiation of IL-structured bucky gels is instrumental for the functionalization of single-walled carbon nanotubes (SWNTs), yielding group coverages of up to one functional group per 60 carbon atoms of the SWNT network. An improved performance is obtained in low viscosity bucky gels, in the order [bmim]BF4> [omim]BF4> [hvim]TF2N (bmim=1-methyl-3- n -butyl imidazolium; hvim=1-vinyl-3- n -hexadecyl imidazolium). With this protocol, the introduction of fluorous-tagged pyrrolidine moieties onto the SWNT surface (1/108 functional coverage) yields novel FT-CNS (carbon nanostructures) with high affinity for fluorinated phases. [source]

Impairment of cytoskeleton-dependent vesicle and organelle translocation in green algae: combined use of a microfocused infrared laser as microbeam and optical tweezers

A. Holzinger
Summary A Nd-YAG laser at 1064 nm is used as optical tweezers to move intracellular objects and a laser microbeam to cause impairment of cytoskeleton tracks and influence intracellular motions in desmidiaceaen green algae. Naturally occurring migrations of large nuclei are inhibited in Micrasterias denticulata and Pleurenterium tumidum when the responsible microtubules are targeted with a laser microbeam generating 180 mW power in the focal plane. Impairment of the microtubule tracks appears to be irreversible, as the nucleus cannot pass the former irradiated area in Pleurenterium or remains abnormally dislocated in Micrasterias. The actin filament-dependent movement of secretory vesicles and smaller particles can be manipulated by the same IR-laser at 90 mW when functioning as optical tweezers. In Closterium lunula particles are displaced from their cytoplasmic tracks for up to 10 m but return to their tracks immediately after removing the light pressure gained by the optical tweezers. The cytoplasmic tracks consist of actin filament cables running parallel to the longitudinal axis of Closterium cells as depicted by Alexa phalloidin staining and confocal laser scanning microscopy. Dynamics and extensibility of the cytoplasmic strands connecting particles to the tracks are also demonstrated in the area of large vacuoles which are surrounded by actin filament bundles. In Micrasterias trapping of secretory vesicles by the optical tweezers causes irreversible malformations of the cell shape. The vesicle accumulation itself dissipates within 30 s after removing the optical tweezers, also indicating reversibility of the effects induced, in the case of actin filament-mediated processes. [source]

Dark soliton generation using dual Brillouin fiber laser in a fiber optic ring resonator

S. F. Hanim
Abstract Stable dark soliton pulses have been successfully generated in an erbium doped dispersion compensated fiber (DCF) using an enhanced dual Brillouin fiber laser (DBFL) scheme.Multidark soliton pulses generation in an S-band erbium doped depressed cladding fiber (DC-EDF) using a multiwavelength Brillouin fiber laser (MW-BFL). Configuration has also been successfully demonstrated. The hybrid amplification from the 300 mW power of Raman pump (RP), 7.7 km long DCF, and 30 m DC-EDF that is being pumped bidirectionally results in a stable multiwavelength Brillouin peaks in the S-band region. Results obtained shows that the insertion of linear gain medium with bidirectional pumping of the DC-EDF into the cavity gives significant amplification and promotes the formation of stokes peaks in the S-band region. The number of Brillouin peaks generated is closely dependent on the DBFL and MW-BFL configuration, the Brillouin pump (BP) signal wavelength, the BP coupling ratio, and the RP power. 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:881,883, 2010; Published online in Wiley InterScience ( DOI 10.1002/mop.25036 [source]

A high-performance wideband cmos low-noise amplifier using inductive series and parallel peaking techniques

Jen-How Lee
Abstract A 1,11 GHz wideband low-noise amplifier (LNA) with good phase linearity properties (group-delay variation is only 35.56 ps across the 3.1,10.6 GHz band of interest) using standard 0.18 ,m CMOS technology is reported. To enhance the bandwidth for achieving both high and flat gain and small group-delay variation, the inductive shunt-peaking technique is adopted in the load of the input stage, while the inductive series-peaking technique is adopted in the input terminal of the output stage. The wideband LNA dissipates 29.46 mW power and achieves input return loss (S11) of ,9.32 to ,9.98 dB, flat forward gain (S21) of 11 1 dB, reverse isolation (S12) of ,46 to ,60 dB, and noise figure of 4.15,4.85 dB over the 3.1,10.6 GHz band of interest. Good 1-dB compression point (P1 dB) of ,14 dBm and input third-order inter-modulation point (IIP3) of ,3 dBm are achieved at 6.4 GHz. The chip area is only 675 ,m 632 ,m excluding the test pads. 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1240,1244, 2008; Published online in Wiley InterScience ( DOI 10.1002/mop.23338 [source]

Laser-improved protein crystallization screening

Neela Yennawar
Screening of proteins for crystallization under laser irradiation was investigated using six proteins: ribonuclease B, glucose dehydrogenase, lysozyme, sorbitol dehydrogenase, fructose dehydrogenase and myoglobin. Shining 532,nm green circularly polarized laser light with a picosecond pulse and 6,mW power for 30,s on newly set-up protein drops showed a marked improvement in the number of screen conditions amenable for crystal growth compared with control drops under identical conditions but without laser exposure. For glucose dehydrogenase and sorbitol dehydrogenase, larger and better quality crystals were formed and the resolution of X-ray diffraction was improved. The speed of crystallization increased in the case of ribonuclease B, lysozyme and sorbitol dehydrogenase. During laser irradiation, the amount of precipitation in the screened drops increased, indicating a transient decrease in protein solubility. At the optimized laser settings, there was no deleterious effect of the laser on crystal growth or on the protein. In the cases of ribonuclease B and lysozyme the crystal packing did not change owing to the laser exposure. [source]