Inactivation of Lactobacillus plantarum by pulsed-microwave irradiation

International Nuclear Information System (INIS)

Shin, J.K.; Pyun, Y.R.

1997-01-01

Suspensions of Lactobacillus plantarum cells were subjected to either conventional heating, continuous microwave (CW) or pulsed microwave (PW) irradiation at 50 degrees C for 30 min. Samples exposed to PW showed greater reductions (2 approximately 4 log) in survival counts than those treated with either conventional heating or CW irradiation. As exposure time increased, PW resulted in a remarkable increase in 260 nm-absorbing compounds that leaked into the suspending menstruum, as compared to CW or conventional heating, indicating that PW irradiated cells were the most injured. The growth of PW irradiated cells was delayed about 24h and the final acidity of the culture broth was about 60 approximately 80% that of other cells treated with conventional heating or CW irradiation

Adaptive response after low level irradiation

Energy Technology Data Exchange (ETDEWEB)

Pelevina, I I; Afanasjev, G G; JaGotlib, V; Tereschenko, D G; Tronov, V A; Serebrjany, A M [Russian Academy of Sciences, Moscow (Russian Federation). Institute of Chemical Physics

1996-02-01

The experiments conducted on cultured HeLa (tissue culture) cells revealed that there is a limit of dose above which adaptive response was not observed and a limit of dose below which this response was not induced. The exposure of cells in the territories with elevated radiation background leads to genome instability which results in enhanced radiosensitivity. Investigations on the blood lymphocytes of people living in contaminated regions revealed that adaptive response was more significant in children whereas in adults there was slight increase. Acute irradiation serves as a tool revealing the changes that took place in DNA during chronic low level irradiations after Chernobyl disaster. (author).

Smelting of Scandium by Microwave Irradiation

Directory of Open Access Journals (Sweden)

Satoshi Fujii

2017-09-01

Full Text Available Scandium is being explored as an alloying element for aluminum alloys, which are gaining importance as high-performance lightweight structural alloys in the transportation industry. A few years ago, Sc was also found to be suitable for use in electrical devices. High-Sc-content ScAlN thin films have attracted significant attention because of their strong piezoelectricity. The piezoelectric response of ScAlN suggests that ScAlN thin films formed on a hard substrate would be suitable surface acoustic wave wideband filters for next-generation wireless communication systems. However, it is often difficult to use ScAlN thin films in MEMS devices—including acoustic ones—because of the extremely high price of metallic Sc, given the difficulty associated with smelting it. Here, we propose a novel process for smelting Sc metal by microwave irradiation. Sc metal was able to be obtained successfully from ScF3 through a microwave-irradiation-based carbon reduction reaction. The reaction temperature for this reduction process was approximately 880°C, which is half of that for the conventional smelting process involving reduction with Ca. Thus, the proposed microwave irradiation process has significant potential for use in the smelting of Sc metal.

Biochemical changes in full fat rice bran stabilized through microwave heating and irradiation treatment

International Nuclear Information System (INIS)

El-Niely, H.F.; Abaullah, M.I.

2007-01-01

The effect of microwave heating and irradiation treatments on proximate composition, lipoxygenase (LOX) activity, free fatty acid (FFA) and fatty acids profile of full fat rice bran were examined. Full fat raw rice bran (FRB) (82.7 g / kg moisture content) was heated in microwave oven at 850 W for up to 4 min or exposed to gamma irradiation up to 25 KGy then packed in polyethylene bags and stored at room temperature for 6 months. Water, protein, fat, ash and crude fiber contents did not change significantly in raw, microwave heated and irradiated samples before and after storage. An exception for this general observation was observed for the moisture content of FRB processed through microwave heating where heating FRB for 4 min dropped the level of moisture to 64.3 g / kg at zero time. Storage of both raw and processed samples had significant (P<0.05) effects on LOX activity. LOX activity of raw samples was significantly increased from its initial value by 43.5% after storage for six months. Microwave heat and irradiated samples showed deactivated LOX and samples exhibited significant changes in LOX activity could be due to treatment dosage. Meanwhile, significant change in LOX activity was observed in processed samples stored for six months. Minor changes were observed due to applied processing methods on FFA and fatty acids composition of full fat rice bran before and after storage. The results suggested that microwave heated or irradiated full fat rice bran packed in polyethylene bags can be stored at room temperature for six months without adverse effect on proximate, fatty acid composition quality and could prevent oxidative and hydrolytic rancidity. However, gamma irradiation treatment at 25 KGy was more effective in this respect. Therefore, it could be concluded that gamma irradiation contributed to optimal processing conditions for FRB stabilization

Effect of microwave irradiation on selective heating behavior and magnetic separation characteristics of Panzhihua ilmenite

International Nuclear Information System (INIS)

Zhao, Wei; Chen, Jin; Chang, Xiaodong; Guo, Shenghui; Srinivasakannan, C.; Chen, Guo; Peng, Jinhui

2014-01-01

Highlights: • Microwave irradiation can be applied effectively and efficiently to the irradiation processes of Panzhihua ilmenite. • The mineral processing properties of microwave treated ilmenite were generally as good as or better than that of initial ilmenite. • The microwave selective heating characteristics of the different minerals and compounds, and the thermal stresses were caused by the uniform heat rate disturbed under microwave irradiation. - Abstract: The influences of microwave irradiation on the surface characteristics of Panzhihua ilmenite were systematically investigated. The crystal structures, surface morphology and surface chemical functional groups of ilmenite were characterized before and after microwave irradiation and magnetic separation for different microwave treatment times by using various methods, such as XRD, SEM, and FT-IR, respectively. XRD analysis showed that the microwave treated ilmenite has the strongest peaks of phase more than that of raw samples, indicates that the crystalline compound of ilmenite increased with the microwave irradiation time. SEM analysis showed the micro-cracking appeared at many grain boundaries of ilmenite after being pretreated by microwave treatment. The separations of ilmenite from gangue minerals were completed and the micro-fissure within ilmenite minerals were also formed, which could be attributed to the microwave selective heating characteristics of the different minerals and compounds, and the thermal stresses were caused by the uniform heat rate disturbed under microwave irradiation. The mineral processing results showed that the magnetic separation characteristics and properties of microwave treated ilmenite samples were better than that of microwave untreated ilmenite samples. It was concluded that microwave irradiation can be applied effectively and efficiently to the irradiation processes of Panzhihua ilmenite

Photolysis of low concentration H2S under UV/VUV irradiation emitted from microwave discharge electrodeless lamps.

Science.gov (United States)

Xia, Lan-Yan; Gu, Ding-Hong; Tan, Jing; Dong, Wen-Bo; Hou, Hui-Qi

2008-04-01

The photolysis of simulating low concentration of hydrogen sulfide malodorous gas was studied under UV irradiation emitted by self-made microwave discharge electrodeless lamps (i.e. microwave UV electrodeless mercury lamp (185/253.7 nm) and iodine lamp (178.3/180.1/183/184.4/187.6/206.2 nm)). Experiments results showed that the removal efficiency (eta H2S) of hydrogen sulfide was decreased with increasing initial H2S concentration and increased slightly with gas residence time; H2S removal efficiency was decreased dramatically with enlarged pipe diameter. Under the experimental conditions with pipe diameter of 36 mm, gas flow rate of 0.42 standard l s(-1), eta H2S was 52% with initial H2S concentration of 19.5 mg m(-3) by microwave mercury lamp, the absolute removal amount (ARA) was 4.30 microg s(-1), and energy yield (EY) was 77.3 mg kW h(-1); eta H2S was 56% with initial H2S concentration of 18.9 mg m(-3) by microwave iodine lamp, the ARA was 4.48 microg s(-1), and the EY was 80.5mg kW h(-1). The main photolysis product was confirmed to be SO4(2-) with IC.

The impact of microwaves irradiation and temperature manipulation ...

African Journals Online (AJOL)

The impact of microwaves irradiation and temperature manipulation for control of stored-products insects. ... This treatment could provide an effective and friendly environmental treatment technique in integrated pest management (IPM) program. Key words: Cold storage, microwaves, saw-toothed grain beetle, cigarette ...

The evaluation of wheat grain odor and color after gamma and microwave irradiation

International Nuclear Information System (INIS)

Warchalewski, J.R.; Gralik, J.; Kusnierz, R.; Zawirska-Wojtasiak, R.; Zabielski, J.

1998-01-01

Wheat grain was exposed to gamma ionising irradiation at selected doses between 0.05-10 kGy and microwave radiation from 45 to 180 sec. The sensory evaluation of a grain odor proved that both applied treatments, gamma and microwave irradiation, did not cause significant changes in the grain odor in comparison to control samples of grain with the exclusion of maximum irradiation dose 10 kGy, and maximum microwave heating time 180 sec. The results obtained after measurement of the grain reflected-light showed that gamma 60 Co irradiation did not cause any changes in grain color. The grain after microwave heating at 90, 120, 180 sec was characterised by significantly higher lightness (L*) value. The total colour difference (δE) between microwave irradiated samples and the control ones was increasing gradually, with the increase in temperature. The yellowness (b*) and the redness (a*) values were statistically significantly higher in the case of 120 and 180 sec of irradiation time comparing to the control sample. (author)

Microwave-Irradiation-Assisted HVAC Filtration for Inactivation of Viral Aerosols (Postprint)

Science.gov (United States)

2012-02-01

Baggiani, A. and Senesi, S. (2004). Effect of Microwave Radiation on Bacillus subtilis Spores . J. Appl. Microbiol. 97: 1220–1227. Damit, B., Lee, C.N...AFRL-RX-TY-TP-2012-0020 MICROWAVE-IRRADIATION-ASSISTED HVAC FILTRATION FOR INACTIVATION OF VIRAL AEROSOLS POSTPRINT Myung-Heui Woo and...12-APR-2011 -- 11-DEC-2011 Microwave Irradiation-Assisted HVAC Filtration for Inactivation of Viral Aerosols (POSTPRINT) FA8650-06-C-5913 0602102F

Comparative studies on the stability of vitamin C and β-carotene of some sliced vegetables and fruit juices exposed to microwaves and γ-irradiation

International Nuclear Information System (INIS)

Farag, R. S.; Basyony, A. E.; Bothyna, S. A.; Safaa, A. A.

2009-01-01

The main purpose of this work was to maintain the integrity and contents of vitamin C and β-carotene, carrots, sweet potatoes and mango serving as main sources of β-carotene, while guava, lime and orange were considered as major reservoir for vitamin C. Microwave and γ-irradiation treatments were applied to keep the vitamin C and β-Carotene of the aforementioned natural sources. The samples were exposed to γ-irradiation at doses of 0.5, 1.0, 1.5,2.0,2.5 and 3 kGy and microwaves for 1,2,3 and 4 min at low power setting. The results indicate that the vitamin C and β-Carotene levels of the samples were variably degraded depending upon the conditions of treatments. Microwave treatment caused decreases in the levels of vitamin C of lime, orange and guava and the extent of reduction was dependent upon the exposure time. In general, γ-irradiation treatment was better than exposure to microwaves for retention of vitamin C and β-carotene and hence extending the shelf life of the food sources under study. The mode of action of these physical methods on vitamin C and β-carotene content is discussed.

The disturbances of lipid metabolism regulation after the prenatal low-level irradiation

International Nuclear Information System (INIS)

Rogov, Yu.I.; Danil'chik, V.S.; Spivak, L.V.; Rubchenya, I.N.

2000-01-01

The objective of this study was to assess the influence of low-level irradiation on lipid metabolism in rats after prenatal exposure. Pregnant rats were irradiated during the period of gestation with the whole final dose 0,5 Gy/rat. The blood lipid fractions were investigated in newborn rats and in 6-month age rats. In irradiated offspring the lipo synthesis processes exceeded lipolysis in comparison with that of the control. The negative consequences of embryo low-level irradiation in the lipid metabolism regulation are discussed in this report. (authors)

Microwave irradiation enhances kinetics of the biomimetic process of hydroxyapatite nanocomposites

International Nuclear Information System (INIS)

Guha, Avijit; Nayar, Suprabha; Thatoi, H N

2010-01-01

In situ synthesized hydroxyapatite-poly(vinyl) alcohol nanocomposite was subjected to microwave irradiation, post synthesis. Interestingly, the aging time of 1 week required for the normal biomimetic process was reduced to 1 h post microwave irradiation, as characterized by x-ray powder diffraction and transmission electron microscopy. The surface topography shows the tendency of tubules to cross-link with the help of microwave energy. The microwave energy seems to provide a directional pull to the polymer chains which could have led to an enhancement of the kinetics of phase formation. (communication)

Malachite green adsorption onto natural zeolite and reuse by microwave irradiation

International Nuclear Information System (INIS)

Han Runping; Wang Yu; Sun Qing; Wang Lulu; Song Jiyun; He Xiaotian; Dou Chanchan

2010-01-01

Natural zeolite was used for the removal of malachite green (MG) from aqueous solution in batch mode and reused by microwave irradiation. The isotherm data were analyzed by the Langmuir, Freundlich, Redlich-Peterson, and Koble-Corrigan isotherm model. The better fit for the equilibrium process was Koble-Corrigan model. The kinetic studies indicated that the adsorption followed the pseudo-second-order kinetic. Thermodynamic calculations showed that the adsorption was spontaneous and endothermic process. Spent zeolite was treated by microwave irradiation and it was found that yield of regeneration was 85.8% in the case of microwave irradiated time 10 min at 160 W.

Enhancement of adhesion between carbon nanotubes and polymer substrates using microwave irradiation

International Nuclear Information System (INIS)

Shim, Hyung Cheoul; Kwak, Yoon Keun; Han, Chang-Soo; Kim, Soohyun

2009-01-01

This paper reports the enhancement of adhesive strength between single-walled carbon nanotubes (SWNTs) and polymer substrates using microwave irradiation of 0-5 min duration at 2.45 GHz and 800 W. Field emission scanning electron microscopy images, ultraviolet-visible data and four-point probe sheet resistance measurement data indicate that microwave irradiation is effective for enhancement of adhesion between SWNTs and polymer substrates. SWNTs could be locally welded onto a polymer substrate due to their active response to microwave irradiation.

Investigation on the rapid degradation of congo red catalyzed by activated carbon powder under microwave irradiation

International Nuclear Information System (INIS)

Zhang Zhaohong; Shan Yabo; Wang Jun; Ling Hongjie; Zang Shuliang; Gao Wei; Zhao Zhe; Zhang Huachun

2007-01-01

Azo dyestuff-congo red in aqueous solution can be degraded rapidly under microwave irradiation in the presence of activated carbon powder. The results showed that the degradation ratio could reach 87.79% for 25 mL total volume with 50 mg/L congo red and 2.0 g/L activated carbon powder under 1.5 min microwave irradiation. Furthermore, within the same irradiation time, congo red could be degraded fully by increasing addition amount (e.g. 3.6 g/L) of activated carbon powder and the degradation ratio was up to 96.49%. Otherwise, with the same addition amount, congo red also could be degraded completely by prolonging irradiation time (e.g. 2.5 min) and the degradation ratio was up to 97.88%. In addition, the influences of microwave irradiation time, initial concentration of congo red, addition amount and used times of activated carbon powder as well as solution acidity on the degradation were discussed in details adopting UV-vis spectra, FT-IR spectra, ion chromatography, high phase liquid chromatography (HPLC) and TOC analysis technologies. Here, the method using activated carbon powder as catalyst under microwave irradiation shows many advantages including high degradation ratios, short reaction time, low costs, no intermediates and no secondary pollution. Therefore, it may be fit for dealing with various azo dyestuff wastewaters on a large scale

Microwave radiation, in the absence of hyperthermia, has no detectable effect on synapsin I levels or phosphorylation

International Nuclear Information System (INIS)

Browning, M.D.; Haycock, J.W.

1988-01-01

Recent reports have indicated that microwave radiation can produce effects on a variety of cell types in vitro. To determine whether microwave radiation might be neurotoxic, the effects of microwave radiation on synapsin I have been examined. Synapsin I is a neuron-specific phosphoprotein that is present in all neurons, where it is localized to the presynaptic terminal and is associated with synaptic vesicles. O'Callaghan and Miller have demonstrated that studies of such neuron-specific proteins can provide reliable indices of neurotoxicity. We have used a radioimmunoassay for synapsin I to determine whether microwave irradiation has any effect on the levels of synapsin I. Neither acute nor chronic exposure to microwave irradiation had any detectable effect on synapsin I levels. We have also examined the calcium-dependent phosphorylation of synapsin I in synaptosomes isolated from rats that had been subjected to microwave radiation. The phosphorylation of synapsin I in synaptosomes reflects numerous components of the presynaptic aspect of neuronal transmission. At intensities below that required to produce mild hyperthermia, no effects of microwave irradiation were seen on synapsin I phosphorylation

The combined effects of e-beam irradiation and microwaves on starch, flour and ingredients

International Nuclear Information System (INIS)

Ferdes, O.S.; Martin, D.; Minea, R.; Tirlea, A.; Badea, M.

1998-01-01

The influences of both microwave field and electron beam irradiation, separately and combined, mainly on physical parameters of corn starch, wheat flour and black pepper were studied. These treatments have been used to achieve the hygienic and microbiological quality requirements of these materials and for their dehydration. The electron-beam irradiation has been carried out by using an ALIN-7 linear accelerator with the following parameters: electron mean energy 6 MeV, mean bean current 10 μA, pulse period 3.5 μs. repetition frequency 100 Hz. For microwave experiments, a special designed microwave applicator consisting of a special cavity, a power controlled generator with a 2.45 GHz standard frequency CW magnetron of 850 W maximum output power was used. The experiments were carried out in 5 variants: microwave treatment solely; electron beam irradiation solely; microwave treatment followed by electron beam irradiation; electron beam irradiation followed by microwave treatment; simultaneous microwave and electron beam treatment. The samples were treated by microwaves at 4 different power values from 250 W to 550 W for 5 different exposure times. The electron beam irradiation took place within the dose range of 1 - 10 kGy, at the same dose rate of approximately 2 kGy/min. The influence of these two physical fields on some common properties (r.h., pH), spectrophotometric (UV-VIS spectra), viscometric (rheograms) and microbiological (CFU/g) properties of the food materials was evaluated. A direct relationship between the variables was observed. The microwave effects are mainly thermal effects, although a non-thermal effect was also observed. The main microbiocidal action is due to the electron beam effect, although the microwave treatment affects sometimes significantly both the microbial population and its sensitivity to irradiation. The combined treatment indicates the presence of a synergistic effect of microwaves and electron-beams, which is of non

Preparation of Orally Disintegrating Tablets Containing Powdered Tea Leaves with Enriched Levels of Bioactive Compounds by Means of Microwave Irradiation Technique.

Science.gov (United States)

Tanaka, Hironori; Iwao, Yasunori; Izumikawa, Masahiro; Sano, Syusuke; Ishida, Hitoshi; Noguchi, Shuji; Itai, Shigeru

2016-01-01

In the present study, a microwave treatment process has been applied to prepare orally disintegrating tablets (ODTs) containing powdered tea leaves with enriched levels of the anti-inflammatory compounds such as chafuroside A (CFA) and chafuroside B (CFB). The use of distilled water as the adsorbed and granulation solvents in this preparation process afforded tablets with a long disintegration time (more than 120 s). The CFA and CFB contents of these tablets did not also change after 4 min of microwave irradiation due to the tablet temperature, which only increased to 100°C. In contrast, the tablet temperature increased up to 140°C after 3 min of microwave irradiation when a 1.68 M Na2HPO4 solution instead of distilled water. Notably, the disintegration time of these tablets was considerably improved (less than 20 s) compared with the microwave-untreated tablets, and there were 7- and 11-fold increases in their CFA and CFB contents. In addition, the operational conditions for the preparation of the tablets were optimized by face-centered composite design based on the following criteria: tablet hardness greater than 13 N, disintegration time less than 30 s and friability less than 0.5%. The requirements translated into X1 (the amount of granulation solvent), X2 (tableting pressure) and X3 (content of the powdered tea leaves) values of 45%, 0.43 kN and 32%, respectively, and the ODTs containing powdered tea leaves prepared under these optimized conditions were found to show excellent tablet properties and contain enriched levels of CFA and CFB.

Effects of postpolymerization microwave irradiation on provisional dental acrylics: physical and mechanical properties.

Science.gov (United States)

Ozkomur, Ahmet; Fortes, Carmen Beatriz Borges

2016-07-26

This study aimed to evaluate the effects of microwave irradiation on the physical and mechanical properties of poly(methyl methacrylate) (PMMA) provisional resins. Twenty bars and 20 disc-shaped specimens were fabricated for each selected provisional restorative material (Dencor and Duralay). Test groups were subjected to microwave irradiation (3 minutes at 600 W) after polymerization. Bar specimens were subjected to a flexural strength test. Disc-shaped specimens were used to evaluate microhardness. Backscattered Raman spectroscopy was employed for each group to define the degree of conversion of the monomer/polymer. The frequency bands corresponding to C = C and C = O groups were used to determine the conversion of methyl methacrylate (MMA) monomers into polymers. Glass transition temperature was determined using a differential scanning calorimeter. Microwave irradiation of both tested autopolymerizing PMMA provisional materials resulted in a statistically significant increase in microhardness, degree of conversion and glass transition temperature values. Also, the results demonstrated a significant increase in flexural strength after postpolymerization microwave irradiation for the Dencor specimens. It is concluded that mechanical and physical properties are positively influenced by microwave irradiation.

Effects of low-level chronic irradiation on aquatic organisms

Energy Technology Data Exchange (ETDEWEB)

Etoh, H. (National Inst. of Radiological Sciences, Chiba (Japan))

1980-10-01

Effects of continual irradiation for a long term on fishes and aquatic invertebrates were outlined. Effects of low-level chronic irradiation on aquatic organisms were less than acute effects induced when the same dose was irradiated once. The radiosensitivity of the genital organ to continual irradiation was high. There was a difference in radiosensitivity of the genital organ between female and male, and the degree of the difference varied according to kinds of animals. In an experiment on continual irradiation of adult killifishes, ova recovered from radiation damage, but spermatozoa did not recover. Incubation rates of eggs obtained from aquatic organisms which lived in water where radioactive sewage flowed into decreased significantly, and the frequency of reverse position of salivary gland chromosomes which were peculiar to exposed organisms increased in larvae of Chironomus tentans.

Remediation of soils contaminated with polychlorinated biphenyls by microwave-irradiated manganese dioxide

International Nuclear Information System (INIS)

Huang Guanyi; Zhao Ling; Dong Yuanhua; Zhang Qin

2011-01-01

The removal of polychlorinated biphenyls (PCBs) using microwave-irradiated manganese dioxide (MnO 2 ) in PCB-contaminated soils under different conditions is investigated. The removal of PCB77 in two actual soil samples exhibits strong pH-dependent behavior, and the removal efficiency is higher in acidic soil (Ali-Perudic Ferrosols) than that in neutral soil (Udic Argosols). The removal kinetics of PCB77 using microwave-irradiated MnO 2 under different experimental conditions fits a pseudo-first-order kinetic model well. Both the removal efficiency and the kinetic constant (k) values of PCB77 in Ali-Perudic Ferrosols considerably increase, although in a nonlinear fashion, as the initial amount of MnO 2 is increased, as the treated soil mass is increased, and as the microwave power is increased. The reactivity of three PCBs (PCB28, PCB77, and PCB118) did not present as a function of the degree of chlorination in the reaction with microwave-irradiated MnO 2 . The pronounced removal of three PCBs in contaminated soil (all above 95%) indicates that MnO 2 in combination with microwave irradiation is promising for technological applications that seek to remediate sites critically polluted with PCBs.

Luminescent and photocatalytic properties of cadmium sulfide nanoparticles synthesized via microwave irradiation

International Nuclear Information System (INIS)

Yang Huaming; Huang Chenghuan; Li Xianwei; Shi Rongrong; Zhang Ke

2005-01-01

Uniform cadmium sulfide (CdS) nanoparticles of about 6 nm in crystal size have been successfully synthesized via microwave irradiation. The as-prepared sample has a uniform morphology and high purity. The red photoluminescence spectrum of the CdS nanoparticles displays a strong peak at 602 nm by using a 300 nm excitation wavelength. The photocatalytic oxidation of methyl orange (MeO) in CdS suspensions under ultraviolet illumination was investigated. The results indicate that a low pH value (pH 2.0) and low reaction temperatures (20-30 deg. C) will facilitate the decolorization of the MeO solution. The photodegradation degree decreases with increasing the pH value and temperature of solution. The efficiency of the recycled CdS semiconductor becomes lower due to the deposit of elemental Cd on the CdS surface, which weakens the photocatalytic activity. The luminescent and photocatalytic mechanisms of the as-prepared CdS nanoparticles were primarily discussed. Microwave irradiation is proved to be a convenient, efficient and environmental-friendly one-step route to synthesize nanoparticles

The microwave heating mechanism of N-(4-methoxybenzyliden)-4-butylaniline in liquid crystalline and isotropic phases as determined using in situ microwave irradiation NMR spectroscopy.

Science.gov (United States)

Tasei, Yugo; Tanigawa, Fumikazu; Kawamura, Izuru; Fujito, Teruaki; Sato, Motoyasu; Naito, Akira

2015-04-14

Microwave heating effects are widely used in the acceleration of organic, polymerization and enzymatic reactions. These effects are primarily caused by the local heating induced by microwave irradiation. However, the detailed molecular mechanisms associated with microwave heating effects on the chemical reactions are not yet well understood. This study investigated the microwave heating effect of N-(4-methoxybenzylidene)-4-butylaniline (MBBA) in liquid crystalline and isotropic phases using in situ microwave irradiation nuclear magnetic resonance (NMR) spectroscopy, by obtaining (1)H NMR spectra of MBBA under microwave irradiation. When heated simply using the temperature control unit of the NMR instrument, the liquid crystalline MBBA was converted to the isotropic phase exactly at its phase transition temperature (Tc) of 41 °C. The application of microwave irradiation at 130 W for 90 s while maintaining the instrument temperature at 20 °C generated a small amount of isotropic phase within the bulk liquid crystal. The sample temperature of the liquid crystalline state obtained during microwave irradiation was estimated to be 35 °C by assessing the linewidths of the (1)H NMR spectrum. This partial transition to the isotropic phase can be attributed to a non-equilibrium local heating state induced by the microwave irradiation. The application of microwave at 195 W for 5 min to isotropic MBBA while maintaining an instrument temperature of 50 °C raised the sample temperature to 160 °C. In this study, the MBBA temperature during microwave irradiation was estimated by measuring the temperature dependent chemical shifts of individual protons in the sample, and the different protons were found to indicate significantly different temperatures in the molecule. These results suggest that microwave heating polarizes bonds in polar functional groups, and this effect may partly explain the attendant acceleration of organic reactions.

The Synthesis of Unsubstituted Cyclic Imides Using Hydroxylamine under Microwave Irradiation

Directory of Open Access Journals (Sweden)

Yousef Hijji

2008-01-01

Full Text Available Unsubstituted cyclic imides were synthesized from a series of cyclic anhydrides,hydroxylamine hydrochloride (NH2OH·HCl, and 4-N,N-dimethylamino-pyridine (DMAP,base catalyst under microwave irradiation in monomode and multimode microwaves. Thisnovel microwave synthesis produced high yields of the unsubstituted cyclic imides forboth the monomode (61 - 81% and multimode (84 - 97% microwaves.

Advances on simultaneous desulfurization and denitrification using activated carbon irradiated by microwaves.

Science.gov (United States)

Ma, Shuang-Chen; Gao, Li; Ma, Jing-Xiang; Jin, Xin; Yao, Juan-Juan; Zhao, Yi

2012-06-01

This paper describes the research background and chemistry of desulfurization and denitrification technology using microwave irradiation. Microwave-induced catalysis combined with activated carbon adsorption and reduction can reduce nitric oxide to nitrogen and sulfur dioxide to sulfur from flue gas effectively. This paper also highlights the main drawbacks of this technology and discusses future development trends. It is reported that the removal of sulfur dioxide and nitric oxide using microwave irradiation has broad prospects for development in the field of air pollution control.

Microwave irradiation biodiesel processing of waste cooking oil

Science.gov (United States)

Motasemi, Farough; Ani, Farid Nasir

2012-06-01

Major part of the world's total energy output is generated from fossil fuels, consequently its consumption has been continuously increased which accelerates the depletion of fossil fuel reserves and also increases the price of these valuable limited resources. Biodiesel is a renewable, non-toxic and biodegradable diesel fuel which it can be the best environmentally friendly and easily attainable alternative for fossil fuels. The costs of feedstock and production process are two important factors which are particularly against large-scale biodiesel production. This study is intended to optimize three critical reaction parameters including intensity of mixing, microwave exit power and reaction time from the transesterification of waste cooking oil by using microwave irradiation in an attempt to reduce the production cost of biodiesel. To arrest the reaction, similar quantities of methanol/oil molar ratio (6:1) and potassium hydroxide (2% wt) as the catalyst were used. The results showed that the best yield percentage (95%) was obtained using 300W microwave exit power, 300 rpm stirrer speed (intensity of mixing) and 78°C for 5 min. It was observed that increasing the intensity of mixing greatly ameliorates the yield percentage of biodiesel (up to 17%). Moreover, the results demonstrate that increasing the reaction time in the low microwave exit power (100W) improves the yield percentage of biodiesel, while it has a negative effect on the conversion yield in the higher microwave exit power (300W). From the obtained results it was clear that FAME was within the standards of biodiesel fuel.

Low level chronic irradiation of salmon. Annual progress report

International Nuclear Information System (INIS)

Hershberger, W.K.; Donaldson, L.R.; Bonham, K.; Brannon, E.L.

1975-01-01

A question of primary importance in the use of nuclear energy is what effect the effluent from a reactor will have on the aquatic life in the water used for cooling. Of particular concern in the Pacific Northwest are the effects of chronic irradiation on salmon that use the rivers for spawning and nursery area. The present program was designed in the early days of the atomic era to address this concern, and to provide some insight into the long-term consequences of exposure of fish to chronic, low levels of irradiation. The experimental techniques are described and data are summarized on irradiation effects on the entire life cycle of the chinook salmon. Also, long-term effects transmitted to future generations were assessed in F 1 offspring of irradiated parents

Effects of irradiation on fungi and fumonisin B(1) in corn, and of microwave-popping on fumonisins in popcorn.

Science.gov (United States)

D'Ovidio, K L; Trucksess, M W; Devries, J W; Bean, G

2007-07-01

Fumonisins are metabolites produced in corn primarily by the fungus Fusarium verticillioides (F. moniliforme) and are toxic to humans and animals. Fumonisin B(1) (FB(1)) is the primary fumonisin produced and is found frequently in corn kernels, some of which may be used as food or food ingredients. A three-part study was conducted to determine the effects of gamma- and electron beam irradiation on the levels of fumonisins in naturally contaminated field corn, and the effects of microwave-popping on fumonisins in selected, naturally contaminated popcorn. To date, no effective means have been found to reduce consistently mycotoxin levels once foods are contaminated. Aqueous solutions of FB(1) at various concentrations, samples of whole corn, and samples of ground corn containing known levels of FB(1) were irradiated with various levels of cobalt and electron beam irradiation. Popcorn samples, taken from the reject streams of popcorn processing, were popped using normal microwave-popping conditions. FB(1) in aqueous solutions was reduced by 99.7% using a minimal level of irradiation (0.5 kGray). Gamma- and electron beam irradiation did not significantly reduce levels of FB(1) in whole and ground corn. Aspergillus sp., Penicillium sp. and Fusarium sp. fungi were totally eliminated at 30 kGray in ground corn and at 100 kGray in whole corn. The normal commercial cleaning processes for microwave popcorn before packaging reduced fumonisins to fumonisins resulted in significant reduction of the mould toxin.

MICROWAVE IRRADIATION AND CROSS-LINKING OF COLLAGEN

NARCIS (Netherlands)

VISSER, CE; VOUTE, ABE; OOSTING, J; BOON, ME; KOK, LP

1992-01-01

In a multifactorial experiment, dermal sheep collagen was treated in diluted glutaraldehyde solutions, 70% ethyl alcohol, Cialit 1:5000, and distilled water for 1, 3 and 5 min, respectively, in combination with microwave irradiation at different temperature settings. The shrinkage temperature

Microwave irradiation of lignocellulosic materials, 4: Enhancement of enzymatic susceptibility of microwave-irradiated softwoods

International Nuclear Information System (INIS)

Azuma, J.; Higashino, J.; Isaka, M.; Koshijima, T.

1985-01-01

Effect of microwave irradiation on the enzymatic susceptibility of various softwoods was investigated. The pH values of the reaction liquor dropped with increasing temperature to 2.9-3.3 at 230°C, consistent with increase in acidity (0.5-0.85 meq at 230-239° C). Above approximately 180°C, hemicellulose underwent acid-mediated autohydrolysis and became water-soluble yielding a mixture of oligosaccharides and monosaccharides. The composition of water-soluble portion was similar for all wood species tested. The maximum extents of saccharification below 240°C ranged between 36-62% for softwoods, while those for hardwoods were between 88-93%. The present investigation confirmed that microwave pretreatment enhanced the enzymatic susceptibility of various softwoods. However, further attempt should be needed to give higher values equal to those for hardwoods. (author)

A comparison of gamma-irradiation and microwave treatments on the lipids and microbiological pattern of beef liver

International Nuclear Information System (INIS)

Farag, R.S.; Daw, Z.Y.; Farag, S.A.; Abd El-Wahab, S.A.E.

2000-01-01

The effects of gamma-irradiation treatments (0, 2.5, 5 and, 10 kGy) and microwaves generated from an oven at low and defrost settings for 0.5, 1 and 2 min on the chemical composition and microbiological aspects of beef liver samples were studied. The chemical and microbiological analyses were performed on the non-treated and treated beef liver immediately after treatments and during frozen storage (-18 degree) for 3 months. The chemical analyses of beef liver lipids showed that acid, peroxide and TBA ( Thiobarbituric acid) values were slightly increased after irradiation treatments and also during frozen storage (-18 degree c). On the contrary, iodine value of the treated beef liver was decreased. Irradiation treatments remarkably reduced the total bacterial counts in beef liver. The percent reduction of bacterial load for beef liver exposed to microwaves generated from an oven at defrost mode for 2 min and after 3 months at (-18 degree c) was 62%. The bacterial load for beef liver exposed to gamma-irradiation at 10 kGy after 3 months at -18 degree c was decreased by 98%. Hence, gamma-irradiation treatment was far better than microwave treatment for inhibiting the multiplication of the associated microorganisms with beef liver. Salmonellae was not detected in non-irradiated and irradiated beef liver throughout the storage period

In Situ Spectroscopic Analysis of the Carbothermal Reduction Process of Iron Oxides during Microwave Irradiation

Directory of Open Access Journals (Sweden)

Jun Fukushima

2018-01-01

Full Text Available The effects of microwave plasma induction and reduction on the promotion of the carbothermal reduction of iron oxides (α-Fe2O3, γ-Fe2O3, and Fe3O4 are investigated using in situ emission spectroscopy measurements during 2.45 GHz microwave processing, and the plasma discharge (such as CN and N2 is measured during microwave E-field irradiation. It is shown that CN gas or excited CN molecules contribute to the iron oxide reduction reactions, as well as to the thermal reduction. On the other hand, no plasma is generated during microwave H-field irradiation, resulting in thermal reduction. Magnetite strongly interacts with the microwave H-field, and the reduction reaction is clearly promoted by microwave H-field irradiation, as well as thermal reduction reaction.

Plasma filamentation and shock wave enhancement in microwave rockets by combining low-frequency microwaves with external magnetic field

International Nuclear Information System (INIS)

Takahashi, Masayuki; Ohnishi, Naofumi

2016-01-01

A filamentary plasma is reproduced based on a fully kinetic model of electron and ion transports coupled with electromagnetic wave propagation. The discharge plasma transits from discrete to diffusive patterns at a 110-GHz breakdown, with decrease in the ambient pressure, because of the rapid electron diffusion that occurs during an increase in the propagation speed of the ionization front. A discrete plasma is obtained at low pressures when a low-frequency microwave is irradiated because the ionization process becomes more dominant than the electron diffusion, when the electrons are effectively heated by the low-frequency microwave. The propagation speed of the plasma increases with decrease in the incident microwave frequency because of the higher ionization frequency and faster plasma diffusion resulting from the increase in the energy-absorption rate. An external magnetic field is applied to the breakdown volume, which induces plasma filamentation at lower pressures because the electron diffusion is suppressed by the magnetic field. The thrust performance of a microwave rocket is improved by the magnetic fields corresponding to the electron cyclotron resonance (ECR) and its higher-harmonic heating, because slower propagation of the ionization front and larger energy-absorption rates are obtained at lower pressures. It would be advantageous if the fundamental mode of ECR heating is coupled with a lower frequency microwave instead of combining the higher-harmonic ECR heating with the higher frequency microwave. This can improve the thrust performance with smaller magnetic fields even if the propagation speed increases because of the decrease in the incident microwave frequency.

Plasma filamentation and shock wave enhancement in microwave rockets by combining low-frequency microwaves with external magnetic field

Energy Technology Data Exchange (ETDEWEB)

Takahashi, Masayuki, E-mail: m.takahashi@al.t.u-tokyo.ac.jp [Department of Aeronautics and Astronautics, The University of Tokyo, Bunkyo-ku 113-8656 (Japan); Ohnishi, Naofumi [Department of Aerospace Engineering, Tohoku University, Sendai 980-8579 (Japan)

2016-08-14

A filamentary plasma is reproduced based on a fully kinetic model of electron and ion transports coupled with electromagnetic wave propagation. The discharge plasma transits from discrete to diffusive patterns at a 110-GHz breakdown, with decrease in the ambient pressure, because of the rapid electron diffusion that occurs during an increase in the propagation speed of the ionization front. A discrete plasma is obtained at low pressures when a low-frequency microwave is irradiated because the ionization process becomes more dominant than the electron diffusion, when the electrons are effectively heated by the low-frequency microwave. The propagation speed of the plasma increases with decrease in the incident microwave frequency because of the higher ionization frequency and faster plasma diffusion resulting from the increase in the energy-absorption rate. An external magnetic field is applied to the breakdown volume, which induces plasma filamentation at lower pressures because the electron diffusion is suppressed by the magnetic field. The thrust performance of a microwave rocket is improved by the magnetic fields corresponding to the electron cyclotron resonance (ECR) and its higher-harmonic heating, because slower propagation of the ionization front and larger energy-absorption rates are obtained at lower pressures. It would be advantageous if the fundamental mode of ECR heating is coupled with a lower frequency microwave instead of combining the higher-harmonic ECR heating with the higher frequency microwave. This can improve the thrust performance with smaller magnetic fields even if the propagation speed increases because of the decrease in the incident microwave frequency.

Evidence from mammalian studies on genetic effects of low level irradiation

International Nuclear Information System (INIS)

Searle, A.G.

1989-01-01

The major components of genetic damage and associated human risks are discussed, together with the experimental evidence on induction rates of chromosome anomalies in mice, and monkeys male and female germ cells, using low and high LET low level irradiation. (UK)

Karyometric observations of WISH cell cultures irradiated with 3 GHz microwaves

Energy Technology Data Exchange (ETDEWEB)

Szmigielski, S.; Luczak, M.; Wiranowska, M.

1975-01-01

WISH cell cultures 24 hours after passage were irradiated with 3 GHz microwaves (10 cm) at far field conditions in free space (anechoic chamber) for 30 minutes, at field power density 5 or 20 mW/cm/sup 2/. Within 1, 24, and 48 hours of the exposure to microwave fields the volumes of nuclei and nucleoli were measured with the use of a micrometer, and logvolumes and nucleo-nucleolar ratios were calculated. Under the applied irradiation conditions the culture medium temperature did not exceed 37/sup 0/C. In cultures irradiated at field power density 20 mW/cm/sup 2/ increased number of cells with small nuclei and enlarged nucleoli was noted within 1 hour of the exposure. Within 24 and 48 hours after irradiation the nucleolar volume showed a slight decrease, whereas the nuclear volume increased. In cultures irradiated at field power density 5 mW/cm/sup 2/ increased numbers of cells with enlarged nuclei and nucleoli were found. Analysis of the distribution curves of nuclear and nucleolar volumes suggests that non-thermal power densities of microwaves stimulate the metabolism of cell cultures. However, at higher power densities (20 mW/cm/sup 2/) the stimulation phase is preceded by a period of reduced viability of cell cultures.

2.45-GHz microwave irradiation adversely affects reproductive function in male mouse, Mus musculus by inducing oxidative and nitrosative stress.

Science.gov (United States)

Shahin, S; Mishra, V; Singh, S P; Chaturvedi, C M

2014-05-01

Electromagnetic radiations are reported to produce long-term and short-term biological effects, which are of great concern to human health due to increasing use of devices emitting EMR especially microwave (MW) radiation in our daily life. In view of the unavoidable use of MW emitting devices (microwaves oven, mobile phones, Wi-Fi, etc.) and their harmful effects on biological system, it was thought worthwhile to investigate the long-term effects of low-level MW irradiation on the reproductive function of male Swiss strain mice and its mechanism of action. Twelve-week-old mice were exposed to non-thermal low-level 2.45-GHz MW radiation (CW for 2 h/day for 30 days, power density = 0.029812 mW/cm(2) and SAR = 0.018 W/Kg). Sperm count and sperm viability test were done as well as vital organs were processed to study different stress parameters. Plasma was used for testosterone and testis for 3β HSD assay. Immunohistochemistry of 3β HSD and nitric oxide synthase (i-NOS) was also performed in testis. We observed that MW irradiation induced a significant decrease in sperm count and sperm viability along with the decrease in seminiferous tubule diameter and degeneration of seminiferous tubules. Reduction in testicular 3β HSD activity and plasma testosterone levels was also noted in the exposed group of mice. Increased expression of testicular i-NOS was observed in the MW-irradiated group of mice. Further, these adverse reproductive effects suggest that chronic exposure to nonionizing MW radiation may lead to infertility via free radical species-mediated pathway.

Live demonstration: Screen printed, microwave based level sensor for automated drug delivery

KAUST Repository

Karimi, Muhammad Akram

2018-01-02

Level sensors find numerous applications in many industries to automate the processes involving chemicals. Recently, some commercial ultrasound based level sensors are also being used to automate the drug delivery process [1]. Some of the most desirable features of level sensors to be used for medical use are their non-intrusiveness, low cost and consistent performance. In this demo, we will present a completely new method of sensing the liquid level using microwaves. It is a common stereotype to consider microwaves sensing mechanism as being expensive. Unlike usual expensive, intrusive and bulky microwave methods of level sensing using guided radars, we will present an extremely low cost printed, non-intrusive microwave sensor to reliably sense the liquid level.

Waste treatment by microwave and electron beam irradiation

International Nuclear Information System (INIS)

Martin, D.; Craciun, G.; Manaila, E.; Ighigeanu, D; Oproiu, C.; Iacob, N.; Togoe, I.; Margaritescu, I.

2007-01-01

Comparative results obtained by applying separate and combined (successive and simultaneous) electron beam (EB) and microwave (MW) irradiation to waste treatment, such as food residuals (minced beef, wheat bran and wheat flour) and sewage sludge performed from a food industry wastewater treatment station (vegetable oil plant), are presented. The research results demonstrated that the simultaneous EB and MW irradiation produces the biggest reduction of microorganisms. The tests also demonstrated that the irradiation time and the upper limit of required EB absorbed dose, which ensures a complete sterilization effect, could be reduced by a factor of two by an additional use of MW energy to EB irradiation

Producing ashless coal extracts by microwave irradiation

Energy Technology Data Exchange (ETDEWEB)

Ozgur Sonmez; Elife Sultan Giray [Mersin University, Mersin (Turkey). Department of Chemistry

2011-06-15

To produce ashless coal extracts, three Turkish coals were extracted with N-methyl-2-pyrrolidinone (NMP), NMP/ethylenediamine (EDA) (17/1, vol/vol) mixture and NMP/tetralin (9/1, vol/vol) mixture through thermal extraction and microwave extraction. Solvent extraction by microwave irradiation (MI) was found to be more effective than that by thermal extraction. Extraction yield of coals in NMP enhanced by addition of a little EDA, but tetralin addition showed variances according to extraction method used. While tetralin addition caused a decrease in the thermal extraction yield, it increased the yield of the extraction by MI. Following the extraction, the solid extracts were produced with ash content ranging from 0.11% to 1.1%. Ash content of solid extract obtained from microwave extraction are less than ash contents of solid extracts obtained from thermal extraction. 34 refs., 7 figs., 5 tabs.

Low-level laser irradiation induces in vitro proliferation of mesenchymal stem cells

International Nuclear Information System (INIS)

Barboza, Carlos Augusto Galvão; Ginani, Fernanda; Soares, Diego Moura; Henriques, Águida Cristina Gomes; Freitas, Roseana de Almeida

2014-01-01

To evaluate the effect of low-level laser irradiation on the proliferation and possible nuclear morphological changes of mouse mesenchymal stem cells. Mesenchymal stem cells derived from bone marrow and adipose tissue were submitted to two applications (T0 and T48 hours) of low-level laser irradiation (660nm; doses of 0.5 and 1.0J/cm"2). The trypan blue assay was used to evaluate cell viability, and growth curves were used to analyze proliferation at zero, 24, 48, and 72 hours. Nuclear alterations were evaluated by staining with DAPI (4'-6-diamidino-2-phenylindole) at 72 hours. Bone marrow-derived mesenchymal stem cells responded to laser therapy in a dose-dependent manner. Higher cell growth was observed when the cells were irradiated with a dose of 1.0J/cm"2, especially after 24 hours (p<0.01). Adipose-derived mesenchymal stem cells responded better to a dose of 1.0J/cm"2, but higher cell proliferation was observed after 48 hours (p<0.05) and 72 hours (p<0.01). Neither nuclear alterations nor a significant change in cell viability was detected in the studied groups. Low-level laser irradiation stimulated the proliferation of mouse mesenchymal stem cells without causing nuclear alterations. The biostimulation of mesenchymal stem cells using laser therapy might be an important tool for regenerative therapy and tissue engineering

Transesterification of used vegetable oil catalyzed by barium oxide under simultaneous microwave and ultrasound irradiations

International Nuclear Information System (INIS)

Martinez-Guerra, Edith; Gude, Veera Gnaneswar

2014-01-01

Graphical abstract: Transesterification reaction mediated by simultaneous microwave and ultrasound irradiations with barium oxide (BaO) heterogeneous catalyst. - Highlights: • Synergistic effect of simultaneous microwave/ultrasound irradiations was evaluated. • Yields were higher for the MW/US reactions compared to MW or US individually. • BaO catalyzed MW/US transesterification reaction is more environmental-friendly. • BaO catalyzed MW/US transesterification reaction provides better biodiesel yields. • Optimum power density must be identified for energy-efficient biodiesel production. - Abstract: This study presents a novel application of simultaneous microwave and ultrasound (MW/US) irradiations on transesterification of used vegetable oil catalyzed by barium oxide, heterogeneous catalyst. Experiments were conducted to study the optimum process conditions, synergistic effect of microwave and ultrasound irradiations and the effect of power density. From the process parametric optimization study, the following conditions were determined as optimum: 6:1 methanol to oil ratio, 0.75% barium oxide catalyst by wt.%, and 2 min of reaction time at a combined power output rate of 200 W (100/100 MW/US). The biodiesel yields were higher for the simultaneous MW/US mediated reactions (∼93.5%) when compared to MW (91%) and US (83.5%) irradiations individually. Additionally, the effect of power density and a discussion on the synergistic effect of the microwave and ultrasound mediated reactions were presented. A power density of 7.6 W/mL appears to be effective for MW, and MW/US irradiated reactions (94.4% and 94.7% biodiesel yields respectively), while a power density of 5.1 W/mL was appropriate for ultrasound irradiation (93.5%). This study concludes that the combined microwave and ultrasound irradiations result in a synergistic effect that reduces the heterogeneity of the transesterification reaction catalyzed by heterogeneous catalysts to enhance the biodiesel

Comparative study on sulphur reduction from heavy petroleum - Solvent extraction and microwave irradiation approach

Energy Technology Data Exchange (ETDEWEB)

Mohammed, Abdullahi Dyadya; Isah, Abubakar Garba; Umaru, Musa; Ahmed, Shehu [Department of Chemical Engineering, Federal University of Technology, P.M.B 65, Minna (Nigeria); Abdullahi, Yababa Nma [National Petroleum Investment Management Services (Nigeria National Petroleum Corporation), Lagos (Nigeria)

2012-07-01

Sulphur- containing compounds in heavy crude oils are undesirable in refining process as they affect the quality of the final product, cause catalyst poisoning and deactivation in catalytic converters as well as causing corrosion problems in oil pipelines, pumps and refining equipment aside environmental pollution from their combustion and high processing cost. Sulphur reduction has being studied using microwave irradiation set at 300W for 10 and 15minutes and oxidative- solvent extraction method using n- heptane and methanol by 1:1, 1:2 and 1:3 crude- solvent ratios after being oxidized with hydrogen peroxide, H2O2 oxidants. Percentage sulphur removal with n- heptane solvent by 1:1 and 1:2 are 81.73 and 85.47%; but extraction using methanol by different observed ratios gave less sulphur reduction. Indeed when microwave irradiated at 300W for 10 and 15minutes, 53.68 and 78.45% reduction were achieved. This indicates that microwave irradiation had caused oxidation by air in the oven cavity and results to formation of alkyl radicals and sulphoxide from sulphur compound in the petroleum. The prevailing sulphur found in the crude going by FT-IR results is sulphides which oxidized to sulphoxide or sulphones. It is clear that sulphur extraction with heptane is more efficient than microwave irradiation but economically due to demands for solvent and its industrial usage microwave irradiation can serve as alternative substitute for sulphur reduction in petroleum. Sulphur reduction by microwave radiation should be up- scaled from laboratory to a pilot plant without involving extraction column in the refining.

A microwave applicator for uniform irradiation by circularly polarized waves in an anechoic chamber

Science.gov (United States)

Chiang, W. Y.; Wu, M. H.; Wu, K. L.; Lin, M. H.; Teng, H. H.; Tsai, Y. F.; Ko, C. C.; Yang, E. C.; Jiang, J. A.; Barnett, L. R.; Chu, K. R.

2014-08-01

Microwave applicators are widely employed for materials heating in scientific research and industrial applications, such as food processing, wood drying, ceramic sintering, chemical synthesis, waste treatment, and insect control. For the majority of microwave applicators, materials are heated in the standing waves of a resonant cavity, which can be highly efficient in energy consumption, but often lacks the field uniformity and controllability required for a scientific study. Here, we report a microwave applicator for rapid heating of small samples by highly uniform irradiation. It features an anechoic chamber, a 24-GHz microwave source, and a linear-to-circular polarization converter. With a rather low energy efficiency, such an applicator functions mainly as a research tool. This paper discusses the significance of its special features and describes the structure, in situ diagnostic tools, calculated and measured field patterns, and a preliminary heating test of the overall system.

A microwave applicator for uniform irradiation by circularly polarized waves in an anechoic chamber

Energy Technology Data Exchange (ETDEWEB)

Chiang, W. Y.; Wu, M. H.; Wu, K. L.; Lin, M. H.; Teng, H. H.; Barnett, L. R.; Chu, K. R., E-mail: krchu@yahoo.com.tw [Department of Physics, National Taiwan University, Taipei, Taiwan (China); Tsai, Y. F.; Ko, C. C.; Yang, E. C. [Department of Entomology, National Taiwan University, Taipei, Taiwan (China); Jiang, J. A. [Department of Bio-Industrial Mechatronics Engineering, National Taiwan University, Taipei, Taiwan (China)

2014-08-15

Microwave applicators are widely employed for materials heating in scientific research and industrial applications, such as food processing, wood drying, ceramic sintering, chemical synthesis, waste treatment, and insect control. For the majority of microwave applicators, materials are heated in the standing waves of a resonant cavity, which can be highly efficient in energy consumption, but often lacks the field uniformity and controllability required for a scientific study. Here, we report a microwave applicator for rapid heating of small samples by highly uniform irradiation. It features an anechoic chamber, a 24-GHz microwave source, and a linear-to-circular polarization converter. With a rather low energy efficiency, such an applicator functions mainly as a research tool. This paper discusses the significance of its special features and describes the structure, in situ diagnostic tools, calculated and measured field patterns, and a preliminary heating test of the overall system.

A microwave applicator for uniform irradiation by circularly polarized waves in an anechoic chamber.

Science.gov (United States)

Chiang, W Y; Wu, M H; Wu, K L; Lin, M H; Teng, H H; Tsai, Y F; Ko, C C; Yang, E C; Jiang, J A; Barnett, L R; Chu, K R

2014-08-01

Microwave applicators are widely employed for materials heating in scientific research and industrial applications, such as food processing, wood drying, ceramic sintering, chemical synthesis, waste treatment, and insect control. For the majority of microwave applicators, materials are heated in the standing waves of a resonant cavity, which can be highly efficient in energy consumption, but often lacks the field uniformity and controllability required for a scientific study. Here, we report a microwave applicator for rapid heating of small samples by highly uniform irradiation. It features an anechoic chamber, a 24-GHz microwave source, and a linear-to-circular polarization converter. With a rather low energy efficiency, such an applicator functions mainly as a research tool. This paper discusses the significance of its special features and describes the structure, in situ diagnostic tools, calculated and measured field patterns, and a preliminary heating test of the overall system.

Natural phosphate-supported palladium: A highly efficient and recyclable catalyst for the suzuki-miyaura coupling under microwave irradiation

KAUST Repository

Hassine, Ayoub; Bouhrara, Mohamed; Sebti, Said; Solhy, Abderrahim; Mahfouz, Remi; Luart, Denis; Lene, Christophe; Fihri, Aziz

2015-01-01

This report explores Suzuki-Miyaura coupling under microwave irradiation, using a new generation of catalyst that is based on natural phosphate (NP) impregnated by palladium. This catalyst was prepared by the treatment of natural phosphate with bis(benzonitrile)palladium(II) chloride in acetone at room temperature. The catalyst displayed high catalytic activity for the Suzuki-Miyaura coupling of aryl bromides and chlorides with aryl boronic acids in pure water and with the use of microwave irradiation. The low-cost and availability of the solid support, mild reaction conditions, high yields of desired products, recyclability of the catalyst and short reaction times are the notable features of these methods.

Natural phosphate-supported palladium: A highly efficient and recyclable catalyst for the suzuki-miyaura coupling under microwave irradiation

KAUST Repository

Hassine, Ayoub

2015-01-19

This report explores Suzuki-Miyaura coupling under microwave irradiation, using a new generation of catalyst that is based on natural phosphate (NP) impregnated by palladium. This catalyst was prepared by the treatment of natural phosphate with bis(benzonitrile)palladium(II) chloride in acetone at room temperature. The catalyst displayed high catalytic activity for the Suzuki-Miyaura coupling of aryl bromides and chlorides with aryl boronic acids in pure water and with the use of microwave irradiation. The low-cost and availability of the solid support, mild reaction conditions, high yields of desired products, recyclability of the catalyst and short reaction times are the notable features of these methods.

Vulcanization of rubber mixtures by simultaneous electron beam and microwave irradiation

Energy Technology Data Exchange (ETDEWEB)

Martin, D. E-mail: martin@ifin.nipne.ro; Ighigeanu, D.; Mateescu, E.; Craciun, G.; Ighigeanu, A

2002-08-01

The comparative results obtained by applying separate electron beam (EB) irradiation and simultaneous EB and microwave (MW) irradiation to vulcanization of rubber mixtures based on natural rubber and polybutadiene rubber with carbon black are presented. In the absence of MW, EB irradiation doses of 200-250 kGy are required in order to obtain a higher vulcanization degree. The irradiation doses as well as irradiation times were markedly diminished, from 2 to 6 times, by simultaneous EB and MW irradiation.

TEM and EELS studies of microwave-irradiation synthesis of bimetallic platinum nanocatalysts

International Nuclear Information System (INIS)

Mathe, N R; Scriba, M R; Coville, N J; Olivier, J E

2014-01-01

Microwave-irradiation (MW) synthesis of nanostructured materials provides for the synthesis of metal nanoparticles, using fast and uniform heating rates. This procedure affords better control of the shape and size of the nanoparticles when compared to conventional methods. In this work, microwave-irradiation was used to produce platinum-cobalt (Pt-Co) and platinum-nickel (Pt-Ni) nanoparticles for use as electrocatalysts in the methanol oxidation reaction. High resolution TEM imaging and EELS studies revealed that these bimetallic nanoparticles form islands or hetero-structures

Low-level laser irradiation induces in vitro proliferation of mesenchymal stem cells

Energy Technology Data Exchange (ETDEWEB)

Barboza, Carlos Augusto Galvão; Ginani, Fernanda [Universidade Federal do Rio Grande do Norte, Natal, RN (Brazil); Soares, Diego Moura [Universidade Federal de Pernambuco, Recife, PE (Brazil); Henriques, Águida Cristina Gomes; Freitas, Roseana de Almeida [Universidade Federal do Rio Grande do Norte, Natal, RN (Brazil)

2014-07-01

To evaluate the effect of low-level laser irradiation on the proliferation and possible nuclear morphological changes of mouse mesenchymal stem cells. Mesenchymal stem cells derived from bone marrow and adipose tissue were submitted to two applications (T0 and T48 hours) of low-level laser irradiation (660nm; doses of 0.5 and 1.0J/cm{sup 2}). The trypan blue assay was used to evaluate cell viability, and growth curves were used to analyze proliferation at zero, 24, 48, and 72 hours. Nuclear alterations were evaluated by staining with DAPI (4'-6-diamidino-2-phenylindole) at 72 hours. Bone marrow-derived mesenchymal stem cells responded to laser therapy in a dose-dependent manner. Higher cell growth was observed when the cells were irradiated with a dose of 1.0J/cm{sup 2}, especially after 24 hours (p<0.01). Adipose-derived mesenchymal stem cells responded better to a dose of 1.0J/cm{sup 2}, but higher cell proliferation was observed after 48 hours (p<0.05) and 72 hours (p<0.01). Neither nuclear alterations nor a significant change in cell viability was detected in the studied groups. Low-level laser irradiation stimulated the proliferation of mouse mesenchymal stem cells without causing nuclear alterations. The biostimulation of mesenchymal stem cells using laser therapy might be an important tool for regenerative therapy and tissue engineering.

Effect of e-beam irradiation and microwave heating on the fatty acid composition and volatile compound profile of grass carp surimi

International Nuclear Information System (INIS)

Zhang, Hongfei; Wang, Wei; Wang, Haiyan; Ye, Qingfu

2017-01-01

In this study, we evaluated the effects of e-beam irradiationпј€1–7 kGyпј‰ and irradiation coupled to microwave heating (e-I-MC, 70 °C internal temperature) on the fatty acid composition and volatile compound profile of grass carp surimi. Compared to control samples, e-beam irradiation generated three novel volatile compounds (heptane, 2,6-dimethyl-nonane, and dimethyl disulfide) and increased the relative proportions of alcohols, aldehydes, and ketones. Meanwhile, e-I-MC significantly increased aldehyde levels and generated five heterocyclic compounds along with these three novel compounds. No significant difference in volatile compounds were detected in e-I-MC samples with increasing irradiation dose (p>0.05), comparing to the control group. E-beam irradiation at 5 and 7 kGy increased the levels of saturated fatty acids (SFAs) and decreased the levels of unsaturated fatty acids (p≤0.05), but did not affect the content of trans fatty acid levels (p>0.05). Irradiation, which had no significant effects on (Eicosapentaenoic acid) EPA, decreased (Docose Hexaenoie Acid) DHA levels. In the e-I-MC group, SFA levels increased and PUFA levels decreased. Additionally, MUFA levels were unaffected and trans fatty acid levels increased slightly following e-I-MC. - Highlights: • E-beam irradiation generated three novel volatile compounds. • E-beam irradiation increased the relative proportions of alcohols, aldehydes, and ketones. • E-beam irradiation coupled to microwave heating increased aldehyde levels and generated five heterocyclic compounds. • E-beam irradiation at 5 and 7 kGy decreased the levels of unsaturated fatty acids, but did not affect trans fatty acid levels.

Deprotection of oximes using urea nitrate under microwave irradiation

Indian Academy of Sciences (India)

Abstract. A new mild and efficient method for the cleavage of oximes to carbonyl compounds using readily available urea nitrate in acetonitrile-water (95 : 5), under microwave irradiation within 2 min, in good yields is reported.

Bending creep in the direction perpendicular to grain during microwave irradiation

International Nuclear Information System (INIS)

Iida, I.

1989-01-01

Bending creep tests in the radial direction perpendicular to the grain were carried out on the thirteen different wood species during the microwave irradiation and during the hot-air drying. The course of moisture content of specimen during creep tests were measured at the same time. And then, relationships between the drying rate and the moisture content, or the creep deflection and the moisture content were investigated and disscussed. Results obtained are as follows : 1) The coefficients of drying rate (K 1 ) during microwave irradiation process were from values of 3.40(hr) -1 to 5.65(hr) -1 for different species. With average value of all woods, there were of 4.73(hr) -1 . Therefore, this value show a value of 5.3 times as much as these of hot-air drying. 2) Creep deflection of woods dried by the microwave heating increase remarkably from the start of the microwave irradiation. 3) Ratio ( y 30 /y m ) of creep deflection y m , in region of ∼30% moisture content, to the maximum creep deflection y m were thought the values differ from each wood species, in no relation with the applied stresses and these values have the constant in a wood. Those were estimated about 0.73 for Icho wood and about 0.44 for Buna wood, and moreover it was about 0.6 with average value for all wood species. Consequently, it was recognized that drying rate became remarkably magnitude value during microwave heating. Creep deflection on the 30% moisture content take beyond about half of the total creep deflection. Conseqently, the large creep deformation developed during the high moisture content process, and it constitute a caractaristic frature of microwave heating

The influence of microwave irradiation on rocks for microwave-assisted underground excavation

Directory of Open Access Journals (Sweden)

Ferri Hassani

2016-02-01

Full Text Available Demand is growing for explosive-free rock breakage systems for civil and mining engineering, and space industry applications. This paper highlights the work being undertaken in the Geomechanics Laboratory of McGill University to make a real application of microwave-assisted mechanical rock breakage to full-face tunneling machines and drilling. Comprehensive laboratory tests investigated the effect of microwave radiation on temperature profiles and strength reduction in hard rocks (norite, granite, and basalt for a range of exposure times and microwave power levels. The heating rate on the surface of the rock specimens linearly decreased with distance between the sample and the microwave antenna, regardless of microwave power level and exposure time. Tensile and uniaxial compressive strengths were reduced with increasing exposure time and power level. Scanning electron micrographs (SEMs highlighted fracture development in treated basalt. It was concluded that the microwave power level has a strong positive influence on the amount of heat damage induced to the rock surface. Numerical simulations of electric field intensity and wave propagation conducted with COMSOL Multiphysics® software generated temperature profiles that were in close agreement with experimental results.

An Expedient Method for the Synthesis of Thiosemicarbazones under Microwave Irradiation in Solvent-free Medium

Institute of Scientific and Technical Information of China (English)

LI, Jian-Ping; ZHENG, Peng-Zhi; ZHU, Jun-Ge; LIU, Rui-Jie; QU, Gui-Rong

2006-01-01

A simple, efficient and eco-friendly method for the synthesis of thiosemicarbazones from thiosemicarbazides and aldehyde under microwave irradiation has been reported, and no solvent and catalyst were used. And the technique of microwave irradiation coupled with solvent-free condition proved to be a quite valuable method in the organic synthesis.

Electron migration in hydrated biopolymers following pulsed irradiation at low temperatures

International Nuclear Information System (INIS)

Lith, D. van.

1987-01-01

Charge migration in biopolymer-water mixtures and the effect of water concentration on the charge migration is investigated by measuring the electrical conductivity and the light emission with the pulse radiolysis technique. A preliminary account of the microwave conductivity observed in hydrated DNA and collagen at low temperature after pulsed irradiation is given. The results show that when hydrated DNA or collagen are irradiated at low temperatures, conductivity transients with microsecond lifetime are observed. It is tentatively concluded that these transients are due to the highly mobile dry electron. The effect of water concentration on mobility, lifetime and migration distance of the electron is discussed. The effect of additives to the hydrated systems on the behaviour of the electron is described. It is shown that the observed effects of the additives confirm the earlier conclusions that the dry electron is the species responsible for the radiation induced conductivity. The water concentration in the DNA- and collagen-systems could be varied only between zero and approximately fifty percent, due to inhomogeneities which occur at higher water concentrations. Experiments on gelatin, a biopolymer which forms homogeneous samples with levels of hydration varying from almost zero to 100% water (ice) are described. Both the radiation induced and the dark microwave conductivity have been studied as a function of water content. Preliminary results of a study of the light emission from pulse irradiated DNA-water mixtures are reported in an attempt to establish a relation between the observed electron migration and the formation of excited states via charge neutralization. (Auth.)

Application of Microwave Irradiation and Heat to Improve Gliadin Detection and Ricin ELISA Throughput with Food Samples

Directory of Open Access Journals (Sweden)

Eric A. E. Garber

2015-06-01

Full Text Available The utility of microwave irradiation to accelerate the onset of equilibrium and improve ELISA performance was examined using ELISAs for the detection of the plant toxin ricin and gliadin. The ricin ELISA normally requires several one hour incubations at 37 °C, a total assay time of approximately five hours, and employs a complex buffer containing PBS, Tween-20®, and non-fat milk. Different energy levels and pulse designs were compared to the use of abbreviated incubation times at 37 °C for the detection of ricin in food. The use of microwave irradiation had no significant advantage over the application of heat using an oven incubator and performed worse with some foods. In contrast, a gliadin ELISA that relied on 30 min incubation steps at room temperature and a salt-based buffer performed better upon irradiation but also displayed improvement upon incubating the microtiter plate at 37 °C. Whether microwave irradiation was advantageous compared to incubation in an oven was inconclusive. However, by abbreviating the incubation time of the ricin ELISA, it was possible to cut the assay time to less than 2 hours and still display LOD values < 10 ppb and recoveries of 78%–98%.

Application of microwave irradiation to organic liquid phase reactions

International Nuclear Information System (INIS)

Huang Kun; Liu Hua; Ji Xuelin

1994-01-01

Microwave irradiation has been used in organic liquid phase reactions to significantly reduce the reaction time and improve the yield. The proposed mechanism, the development of techniques and reactions, such as Diels-Alder, ene, rearrangement reactions etc., are discussed

Nonthermal effect of microwave irradiation on nitrite uptake in Chlamydomonas reinhardtii

International Nuclear Information System (INIS)

Pedrajas, C.; Cotrino, J.

1989-01-01

When cells of the unicellular green alga Chlamydomonas reinhardtii were subjected to microwave irradiation at 2.45 GHz, nitrite uptake kinetics still obeyed the Michaelis-Menten equation, the Km of the process remaining constant, whereas V max increased, which indicates an enhanced nonthermal permeability in irradiated cells. (author)

Ruthenium (4) and ruthenium (3) state in hydrochloric acid solutions under microwave irradiation

International Nuclear Information System (INIS)

Bashilov, A.V.; Kuz'min, N.M.; Nesterov, A.A.; Runov, V.K.

2000-01-01

Reactions of hydration, poly- and depolymerization, oxidation-reduction processes with ruthenium (4) and ruthenium (3) participation are investigated in hydrochloric acid solutions under microwave irradiation by the methods of molecular absorption spectroscopy in UV visible region taking K 4 [Ru 2 OCl 10 ] as an example. Content of state forms of ruthenium (4) and ruthenium (3), absorption characteristics of forming complexes are calculated. Variation of microwave irradiation parameters and HCl concentration permits to prepare solutions containing [RuCl 6 ] 2+ (95 %) and [(RuOH) 2 (H 2 O) 6 (OH) 2 ] 4+ (98 %) preeminently predominant forms. The role of microwave effect directly is established taking as an example the process of ruthenium (4) hydration [ru

On the impact of low power density microwaves in some living tissues

International Nuclear Information System (INIS)

Creanga, M.; Tufescu, D.E.

2006-01-01

The biomedical and ecological interest for the microwave impact on the Earth biosphere is continuously increased since the industrial, military and communication activities strongly contribute to the electromagnetic stress of living bodies. In the next the authors present some of the main results obtained regarding the microwave exposure of various types of biological material: bacteria, fungi, young plant seedlings, dry seeds, animal tissues. The electromagnetic exposure was carried out in open space in well controlled environmental conditions by using 10.75 GHz/1 m W cm -2 microwaves. Biochemical assays and cytogenetic tests have been carried out to reveal the changes induced post irradiation. The response of some pathogen bacteria, have been emphasized by means of turbidimetric measurements - the stimulatory effect being noticed at the level of the microbial population density (the stimulation of the human body microbial flora seems to be one of the side effects of microwave exposures). The behavior of some fungus species was investigated by spectrophotometric assay of various enzyme systems: either inhibitor y or stimulatory effects have been revealed, depending on the species and enzyme peculiarities (certain biotechnological tools could be developed based on fungi exposure to microwaves). The genetic effects of seed exposure have been studied by applying cytogenetic tests to meristem tissues provided by freshly germinated cereal plantlets. Significant rate of chromosomal aberrations has been observed following the microwave exposure as well as stimulatory influence on the proliferation rate (the possibility of plant growth stimulation is suggested). The vegetal tissue cultures (in vitro micro propagated pharmaceutical plants) exposed to low power density microwaves presented increased levels of assimilatory pigments (the controlled development of technical plants for medical uses is proposed). The chlorophyll ratio in young tree seedlings after

On the impact of low power density microwaves in some living tissues

Energy Technology Data Exchange (ETDEWEB)

Creanga, M.; Tufescu, D.E. [Univ. Al. I. Cuza, Faculty of Physics, Iasi (Romania)

2006-07-01

The biomedical and ecological interest for the microwave impact on the Earth biosphere is continuously increased since the industrial, military and communication activities strongly contribute to the electromagnetic stress of living bodies. In the next the authors present some of the main results obtained regarding the microwave exposure of various types of biological material: bacteria, fungi, young plant seedlings, dry seeds, animal tissues. The electromagnetic exposure was carried out in open space in well controlled environmental conditions by using 10.75 GHz/1 m W cm{sup -2} microwaves. Biochemical assays and cytogenetic tests have been carried out to reveal the changes induced post irradiation. The response of some pathogen bacteria, have been emphasized by means of turbidimetric measurements - the stimulatory effect being noticed at the level of the microbial population density (the stimulation of the human body microbial flora seems to be one of the side effects of microwave exposures). The behavior of some fungus species was investigated by spectrophotometric assay of various enzyme systems: either inhibitor y or stimulatory effects have been revealed, depending on the species and enzyme peculiarities (certain biotechnological tools could be developed based on fungi exposure to microwaves). The genetic effects of seed exposure have been studied by applying cytogenetic tests to meristem tissues provided by freshly germinated cereal plantlets. Significant rate of chromosomal aberrations has been observed following the microwave exposure as well as stimulatory influence on the proliferation rate (the possibility of plant growth stimulation is suggested). The vegetal tissue cultures (in vitro micro propagated pharmaceutical plants) exposed to low power density microwaves presented increased levels of assimilatory pigments (the controlled development of technical plants for medical uses is proposed). The chlorophyll ratio in young tree seedlings after

Effect of microwave irradiation on hydrogen sorption properties of hand mixed MgH{sub 2} – 10 wt.% carbon fibers

Energy Technology Data Exchange (ETDEWEB)

Awad, A.S. [Université de Bordeaux, ICMCB-CNRS, 87 Avenue du Dr Schweitzer, F-33600 Pessac (France); LCPM/PR2N, Université Libanaise, Faculté des Sciences 2, 90656 Jdeidet El Matn (Lebanon); Nakhl, M.; Zakhour, M. [LCPM/PR2N, Université Libanaise, Faculté des Sciences 2, 90656 Jdeidet El Matn (Lebanon); Santos, S.F.; Souza, F.L. [Universidade Federal do ABC, Avenida dos Estados 5001, 09210-580 Santo André – SP (Brazil); Bobet, J.-L., E-mail: jean-louis.bobet@u-bordeaux.fr [Université de Bordeaux, ICMCB-CNRS, 87 Avenue du Dr Schweitzer, F-33600 Pessac (France)

2016-08-15

The effect of microwave (MW) irradiation on the hydrogen sorption properties of magnesium powder is explored in the present work. MgH{sub 2} – 10 wt.% CFs (CFs = Carbons Fibers) was prepared by hand mixing, dehydrogenated under microwave irradiation for 20 s and then hydrogenated/dehydrogenated at about 300 °C – 1 MPa and 330 °C–0.03 MPa to investigate the effect of microwave irradiation on the solid/gas sorption properties. It has to be noted that the hydrogen absorption capacity and sorption kinetics of the MgH{sub 2} – 10 wt.% CFs mixture increased after dehydriding under MW irradiation. The MgH{sub 2} – 10 wt.% CFs mixture dehydrogenated by microwave irradiation can absorb about 5.8 wt.% and 5.3 wt.% H at 330 and 300 °C, respectively, within 2 h while the as-prepared MgH{sub 2} – 10 wt.% CFs mixture absorb only 4.6 wt.% H within the same duration. It is also demonstrated that MgH{sub 2} – 10 wt.% CFs mixture dehydrogenated by microwave irradiation exhibited good hydrogen desorption properties and, as an example, a microwave irradiated sample could release 5.8 wt.% H within 1 h at 330 °C in comparison to the as-prepared MgH{sub 2} – 10 wt.% CFs mixture which desorbed 4.4 wt.% H within 3 h. Scanning electron microscopy (SEM) images revealed that the particle sizes of the MW dehydrogenated mixture decreased after several solid/gas sorption cycles. This contribute to the improvement of hydrogen storage properties of the microwaves dehydrogenated MgH{sub 2} – 10 wt.% CFs mixture. In addition, the hydrogenated MgH{sub 2} – 10 wt.% CFs mixture show reproducible and better microwave-assisted dehydriding reaction during second microwaves cycle. - Highlights: • Dehydriding reaction of MgH{sub 2} by microwave method. • Effect of microwaves treatment on the hydrogen sorption properties of Mg. • Effect of discontinuous microwaves irradiation.

Cassava Pulp Hydrolysis under Microwave Irradiation with Oxalic Acid Catalyst for Ethanol Production

Directory of Open Access Journals (Sweden)

Euis Hermiati

2014-07-01

Full Text Available Microwave irradiation is an alternative method of starch hydrolysis that offers a rapid process. The aim of this research was to improve microwave-assisted hydrolysis of cassava pulp by using oxalic acid as a catalyst. Suspension of cassava pulp in 0.5% oxalic acid (1 g/20 mL was subjected to microwave irradiation at 140-230 °C for 5 minutes, with 4 minutes of pre-heating. One gram of fractured activated carbon made of coconut shell was added into a number of suspensions that were subjected to the same conditions of microwave irradiation. The soluble fraction of the hydrolysates was analyzed for its total soluble solids, malto-oligomer distribution, glucose content, pH value, and formation of brown compounds. The effects of the combined severity parameter at a substrate concentration of 5-12.5% on the glucose yield were also evaluated. The highest glucose yield (78% of dry matter was obtained after hydrolysis at 180 °C without activated carbon addition. Heating above 180 °C reduced the glucose yield and increased the pH and the formation of brown compounds. The use of activated carbon in microwave-assisted acid hydrolysis of cassava pulp reduced the glucose yield, but suppressed the formation of brown compounds. The highest glucose yield (70-80% of dry matter was attained at a severity parameter of 1.3-1.5.

The influence of microwave irradiation on thermal properties of main rock-forming minerals

International Nuclear Information System (INIS)

Lu, Gao-ming; Li, Yuan-hui; Hassani, Ferri; Zhang, Xiwei

2017-01-01

Highlights: • Different rock-forming minerals present very different microwave absorption capacity to microwave energy. • The test results can be used to estimate the heating behaviors of rocks to microwave irradiation. • SEM-EDX technique was used to determine the elemental distribution and mineralogical composition. • Ferrum may influence the interacting mechanisms between rock-forming minerals and microwaves. - Abstract: The sample will burst into fragment when the thermal stress induced by thermal expansion greater than the ultimate strength of the rock after microwave irradiation. Microwave-assisted rock fragmentation has been illustrated to be potentially beneficial for mineral processing, mining and geotechnical engineering. In order to have a comprehensive understanding on the influence of microwave on thermo-mechanical properties of rocks, it is necessary to investigate the interaction effect between microwaves and the main rock-forming minerals. In this work, eleven rock-forming minerals were tested in a multimode cavity at 2.45G Hz with a power of 2 kW, subsequently, the Scanning Electron Microscopy–Energy Dispersive X-ray (SEM-EDX) was used to determine the elemental distribution and mineralogical composition of the tested samples. It was observed that different rock-forming minerals present very different susceptibility induced by microwave treatment. Enstatite presents the strongest microwave absorption capacity by a large margin and most of the rock-forming minerals are weak microwave absorbers. It is significant that the results can be used to predict the heating behaviors of rocks subjected to microwave energy. Furthermore, the SEM-EDX elemental analysis demonstrates that the microwave absorption capacity of rock-forming minerals could link to the contribution of the ferrum, which may influence the interacting mechanisms between microwaves and the rock-forming minerals.

Microwave Irradiation

Indian Academy of Sciences (India)

Way to Eco-friendly, Green Chemistry. Rashmi ... The rapid heating of food in the kitchen using microwave ovens ... analysis; application to waste treatment; polymer technology; ... of microwave heating in organic synthesis since the first contri-.

Rapid epoxidation of palm acid oil with lipase action under microwave irradiation

International Nuclear Information System (INIS)

Saifuddin, N.; Wei Zhan Lee; Koh, X.N.; Ramesh, S.; Abdullah, S.F.

2010-01-01

In view of growing environmental concerns and tightened regulations over contaminants and pollution in the environment in recent years, calls for biodegradable and nontoxic vegetable oil-based lubricants are abound. They have very low volatility due to the higher molecular weight of the triacylglycerol molecule and a narrow range of viscosity changes with temperature. Polar ester groups in the molecule are able to adhere to metal surfaces, and therefore, possess good boundary lubrication properties. In addition, vegetable oils have high solubilising power for polar contaminants and additive molecules. However, vegetable oils show poor oxidative and thermal stability primarily due to the presence of unsaturation. The presence of ester functionality also renders these oils susceptible to hydrolytic breakdown. The proposed modification of the vegetable oils is an important manner to obtain potentially useful products using a renewable feedstock. In designing a green process to effectively carry out the epoxidation reaction, we report herein, an inexpensive, practical, safe and environmentally friendly method to epoxidize palm acid oil under extremely mild conditions. This work highlights the increased reaction rate of the epoxidation process when microwave irradiation is introduced. The starting material used is Palm Acid Oil, a by-product of the alkali refining process of palm oil. Acid oil can serve as an inexpensive raw materials and are very good substitute for neat vegetable oil such as palm oil for the production of bio lubricant. It is high in Free Fatty Acids (FFA) and is the ideal material for the epoxidation process due to the importance of FFAs in producing peroxy-acids as an oxygen carrier. The double bonds the triglycerides are reacted with a per acid, generated for safety reasons in situ using hydrogen peroxide. Novozym 435 acts as the catalyst in the process and with its good selectivity, the occurrence of by-products is controlled. The method and

Solventless Lactam Synthesis by Intramolecular Cyclizations of α-Iminoester Derivatives under Microwave Irradiation

Directory of Open Access Journals (Sweden)

Aicha Derdour

2007-03-01

Full Text Available We have previously reported a new synthesis of amides from esters and amines under microwave irradiation, offering much higher yields than those achieved with conventional heating [1]. We have now extended these studies to the ring closure of neat iminoesters I2, I3 and I4-I6 to give five- and six-membered ring lactams L5, L6 and larger lactams L7-L9 (where I means imine and L means lactam, respectively, under both classical heating conditions and microwave irradiation.

[Analgesia evoked by combined effect of corvitin and low-intensity microwaves on acupuncture points in mice of different genetic strains with somatic pain].

Science.gov (United States)

Hura, O V; Bahats'ka, O V; Lymans'kyĭ, Iu P

2011-01-01

The level of analgesia has been investigated in mice of two genotypes C57BL/6J Bl/6j and CBA/CaLac with the somatic pain caused by the formalin test after irradiation of acupuncture point E-36 by microwaves of low intensity (30-300 GHz, density of a stream of capacity of 3-10-9 B(T)/cm2) on a background entered corvitin (20 mg/kg). It is shown, that the action of these two factors causes significant analgesia with different levels: 43% in C57BL/6J Bl/6j mice and 33% in CBA/CaLac mice. The intensity of analgesia after action of microwaves and corvitin exceeds the level attained during separate use of these factors.

Fast preparation of dihydrocyclocitral from citronellal under solventless microwave irradiation

DEFF Research Database (Denmark)

Duus, Fritz; Doan, Nhuan Ngoc; Le, Thach Ngoc

2005-01-01

Dihydrocyclocitral, a useful reagent in organic synthesis, has been synthesized in high yield and with high stereoselectivity from citronellal under microwave irradiation in two steps, involving acetic anhydride under base catalysis, then p-toluene-sulfonic acid on silica gel under solventless...

Role of laser fluence in protein synthesis of cultured DRG neurons following low-level laser irradiation

Science.gov (United States)

Zheng, Liqin; Qiu, Caimin; Wang, Yuhua; Zeng, Yixiu; Yang, Hongqin; Zhang, Yanding; Xie, Shusen

2014-11-01

Low-level lasers have been used to relieve pain in clinical for many years. But the mechanism is not fully clear. In animal models, nitric oxide (NO) has been reported involving in the transmission and modulation of nociceptive signals. So the objective of this study was to establish whether low-level laser with different fluence could stimulate the production of nitric oxide synthese (NOS), which produces NO in cultured primary dorsal root ganglion neurons (DRG neurons). The primary DRG neurons were isolated from healthy Sprague Dawley rats (8-12 weeks of age) and spread on 35 mm culture dishes specially used for confocal microscopy. 24 hours after spreading, cells were irradiated with 658 nm laser for two consecutive days at the energy density of 20, 40, 60 and 80 mJ·cm-2 respectively. Control groups were not exposed to the laser, but were kept under the same conditions as the irradiated ones. The synthesis of NOS after laser irradiation was detected by immunofluorescence assay, and the changes of NOS were evaluated using confocal microscopy and Image J software. The results showed that all the laser fluence could promote the production of NOS in DRG neurons, especially the 60 mJ·cm-2 . These results demonstrated that low-level laser irradiation could modify protein synthesis in a dose- or fluence- dependent manner, and indicated that low-level laser irradiation might achieve the analgesic effect through modulation of NO production.

Alternatives to dose, quality factor and dose equivalent for low level irradiation

International Nuclear Information System (INIS)

Sondhaus, C.A.; Bond, V.P.; Feinendegen, L.E.

1988-01-01

Randomly occurring energy deposition events produced by low levels of ionizing radiation interacting with tissue deliver variable amounts of energy to the sensitive target volumes within a small fraction of the cell population. A model is described in which an experimentally derived function relating event size to cell response probability operates mathematically on the microdosimetric event size distribution characterizing a given irradiation and thus determines the total fractional number of responding cells; this fraction measures the effectiveness of the given radiation. Normalizing to equal numbers of events produced by different radiations and applying this cell response or hit size effectiveness function (HSEF) should define radiation quality, or relative effectiveness, on a more nearly absolute basis than do the absorbed dose and dose evaluation, which are confounded when applied to low level irradiations. Examples using both calculation and experimental data are presented. 15 refs., 18 figs

Degradation of N-nitrosodimethylamine (NDMA) and its precursor dimethylamine (DMA) in mineral micropores induced by microwave irradiation.

Science.gov (United States)

He, Yuanzhen; Cheng, Hefa

2016-05-01

Removal of N-nitrosodimethylamine (NDMA) in drinking water treatment poses a significant technical challenge due to its small molecular size, high polarity and water solubility, and poor biodegradability. Degradation of NDMA and its precursor, dimethylamine (DMA), was investigated by adsorbing them from aqueous solution using porous mineral sorbents, followed by destruction under microwave irradiation. Among the mineral sorbents evaluated, dealuminated ZSM-5 exhibited the highest sorption capacities for NDMA and DMA, which decreased with the density of surface cations present in the micropores. In contrast, the degradation rate of the sorbed NDMA increased with the density of surface cations under microwave irradiation. Evolutions of the degradation products and C/N ratio indicate that the sorbed NDMA and DMA could be eventually mineralized under continuous microwave irradiation. The degradation rate was strongly correlated with the bulk temperature of ZSM-5 and microwave power, which is consistent with the mechanism of pyrolysis caused by formation of micro-scale "hot spots" within the mineral micropores under microwave irradiation. Compared to existing treatment options for NDMA removal, microporous mineral sorption coupled with microwave-induced degradation has the unique advantages of being able to simultaneously remove NDMA and DMA and cause their full mineralization, and thus could serve as a promising alternative method. Copyright © 2016 Elsevier Ltd. All rights reserved.

Over-expression of CXCR4, a stemness enhancer, in human blastocysts by low level laser irradiation

Directory of Open Access Journals (Sweden)

Mohammad Hossein Tahmasbi

2013-09-01

Full Text Available The key role of chemokine receptor CXCR4 in the maintenance of stemness property of stem cells has been shown recently. The low level laser irradiation (LLLI is being used currently in a wide variety of clinical cases as a therapeutic tool for wound healing, relieving pain and destroying tumor cells. The aim of this study was to evaluate the effect of LLLI mimicking low level laser therapy (LLLT on the expression level of CXCR4 gene a few hours after irradiation on human blastocysts. After the development of human embryos to the first grade blastocyst stage, they were irradiated with a low power Ga-Al-As laser at a continuous wavelength of 650 nm and a power output of 30 mW. The total RNA of the irradiated blastocysts and control groups were isolated in groups of 1x2 J/cm2, 2x2 J/cm2, 1x4 J/cm2 and 2x4 J/cm2 LLLI. Specific Real-Time PCR primers were designed to amplify all the two CXCR4 isoforms yet identified. RNA amplifications were done for all the groups. We showed for the first time that LLLI makes the human blastocysts to increase the expression level of CXCR4 a few hours after irradiation. Moreover, it was shown that two irradiation doses with one day interval can cause a significant increase in CXCR4 expression level in human blastocysts. This study revealed that LLLI could be a proliferation motivator for embryonic cell divisions through enhanced over-expression of CXCR4 level.

Synthesis of a 2-Furylpyrazoline Derivative Using Microwave Irradiation

Directory of Open Access Journals (Sweden)

Suban Syed Shafi

2009-08-01

Full Text Available A simple method for the synthesis of pyrazoline derivative containing furan moiety was developed. Thus, 5-(6-bromo-1,3-benzodioxol-5-yl-3-(2-furyl-1-(3-methyl-phenyl-4,5-dihydro-1H-pyrazole was synthesized using microwave irradiation and it was characterized by NMR, IR, and LCMS.

Large-scale synthesis of bismuth sulfide nanorods by microwave irradiation

International Nuclear Information System (INIS)

Wu Jiliang; Qin Fan; Cheng Gang; Li Hui; Zhang Jiuhong; Xie Yaoping; Yang Haijian; Lu Zhong; Yu Xianglin; Chen Rong

2011-01-01

Graphical abstract: Display Omitted Research highlights: → Large-scale Bi 2 S 3 nanorods have been prepared by microwave irradiation methods. → CTAB and β-CD are beneficial to the formation of Bi 2 S 3 nanorods. → DMF, EG and DEG were favorable solvents. → Bismuth and sulfur precursors influenced the size and morphology. → A proposed formation mechanism of Bi 2 S 3 nanorods was summarized. - Abstract: Bismuth sulfide (Bi 2 S 3 ) has attracted considerable interest due to its potential applications in thermoelectric and electronic devices, optoelectronic devices, and biomedicine. In this study, large-scale highly crystalline Bi 2 S 3 nanorods were successfully prepared from bismuth citrate and thiourea (Tu) by microwave irradiation methods. The products were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM, HRTEM) and selected area electron diffraction (SAED). The influences of reaction time, surfactants, solvents, and precursors on the formation of Bi 2 S 3 nanorods were discussed. The microwave irradiation method reduced reaction time by at least 80% in the synthesis of Bi 2 S 3 nanorods compared with the refluxing method. Cetyltrimethylammonium bromide (CTAB) and β-cyclodextrin (β-CD) were found to be beneficial to the formation of Bi 2 S 3 nanorods. N,N-dimethylformamide, ethylene glycol, and diethylene glycol were the favorable solvents in the fabrication of these nanorods. It was found that different bismuth and sulfur precursors influenced the sizes and morphologies of the Bi 2 S 3 nanorods. The proposed growth mechanism of Bi 2 S 3 nanorods was also discussed.

Anti-nutritional Factors and Ruminal Dry Matter and Crude Protein Degradability of Gamma and Microwave Irradiated Native Rapeseed

Directory of Open Access Journals (Sweden)

sayyed roohollah ebrahimimahmoudabad

2016-08-01

. The same procedure was applied to two bags to obtain the 0 h value. The residues were dried and analyzed for DM and CP to determine degradation kinetics of NRS. Digestibility of rumen undegraded CP was estimated using the three-step in vitro procedure. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE was used to monitor protein subfractions and the fate of true proteins of untreated and irradiated NRS in the rumen. Results and Discussion Irradiation had no significant effect on chemical composition, but decreased the total glucosinolate and phytic acid of NRS. This elimination of phytic acid by irradiation is probably due to chemical degradation of phytate to lower inositol phosphates and inositol, by the action of free radicals, which have lower chelating power, or cleavage of the phytate ring itself. The glucosinolate content of untreated NRS in this study, 122.8 mol/g, was reduced up to 30 kGy, but further irradiation had no effect. Major deleterious effects of glucosinolate ingestion in animals include: reduced palatability, decreased growth and reduced production. However, according to our study, gamma and microwave irradiated NRS may be fed to dairy cows at high levels without glucosinolate induced detrimental effects. Gamma and microwave irradiation decreased the washout fraction, degradation rate and effective degradability (ED of DM and CP and increased potentially degradable fraction of DM and CP of NRS. Decreasing CP degradability as a result of irradiation is due to the occurrence of cross-linking of polypeptide chains, denaturation and protein aggregation. Gamma irradiation at doses of 30 and 45 kGy and microwave irradiation increased in vitro CP digestibility of NRS. Irradiation may induce unfolding of the protein and its denaturation, thereby exposing hydrophobic amino acids (especially aromatics that are positional groups for the active sites of pepsin and trypsin enzymes. Moreover, the improvement in CP digestibility may be

Low-level laser irradiation protects the chick embryo chorioallantoic membrane from UV cytotoxicity

Directory of Open Access Journals (Sweden)

Hammami Amira

2018-01-01

Full Text Available Low-level laser therapy or photobiomodulation is the medical use of a very low intensity light in the red to near infrared (wavelengths in the range of 630-940 nm. The present work was conducted to explore the effects of both UV and low-level laser irradiation (LLLI on microcirculation using the in vivo model of the chick embryo chorioallantoic membrane (CAM. The effects were assessed by measuring lipid peroxidation and antioxidant enzyme activity. Cell cytotoxicity, survival and intracellular reactive oxygen species (ROS of the CAM were also evaluated. We found that UV irradiation induced alterations of the vessels, leading to bleeding and extravasation. This effect was intensified after 60 min of exposure to UV irradiation, leading to marked edema. UVA irradiation increased cell cytotoxicity as assessed by lactate dehydrogenase (LDH release (56.23% of control and reduced cell viability as assessed by decreased fluorescein diacetate (FDA fluorescence (56.23% of control. Pretreatment with LLLI prior to UV exposure protected the CAM tissue from UV-mediated cell death. This protective effect was supported by the observation of significantly inhibited lipid peroxidation (from 0.3±0.004 for UV, to 0.177±0.012 after LLLI pretreatment, ROS and O2 -production, as indicated by respective dihydrorhodamine (DHR and dihydroethidium (DHE intensities (from 132.78% of control for UVA, to 95.90% of control for L-UV (DHR, and from 127.34% of control for UVA, to 82.03% of control for L-UV (DHE, and by preventing the increase in oxidative activities. LLLI efficiently protected CAM cells from UV-induced oxidative stress and appeared as a safe protective pretreatment against UV irradiation.

A low cost, printed microwave based level sensor with integrated oscillator readout circuitry

KAUST Repository

Karimi, Muhammad Akram

2017-10-24

This paper presents an extremely low cost, tube conformable, printed T-resonator based microwave level sensor, whose resonance frequency shifts by changing the level of fluids inside the tube. Printed T-resonator forms the frequency selective element of the tunable oscillator. Unlike typical band-pass resonators, T-resonator has a band-notch characteristics because of which it has been integrated with an unstable amplifying unit having negative resistance in the desired frequency range. Magnitude and phase of input reflection coefficient of the transistor has been optimized over the desired frequency range. Phase flattening technique has been introduced to maximize the frequency shift of the oscillator. With the help of this technique, we were able to enhance the percentage tuning of the oscillator manifolds which resulted into a level sensor with higher sensitivity. The interface level of fluids (oil and water in our case) causes a relative change in oscillation frequency by more than 50% compared to maximum frequency shift of 8% reported earlier with dielectric tunable oscillators.

Levels of 2-dodecylcyclobutanone in ground beef patties irradiated by low-energy X-ray and gamma rays.

Science.gov (United States)

Hijaz, Faraj M; Smith, J Scott

2010-01-01

Food irradiation improves food safety and maintains food quality by controlling microorganisms and extending shelf life. However, acceptance and commercial adoption of food irradiation is still low. Consumer groups such as Public Citizen and the Food and Water Watch have opposed irradiation because of the formation of 2-alkylcyclobutanones (2-ACBs) in irradiated, lipid-containing foods. The objectives of this study were to measure and to compare the level of 2-dodecylcyclobutanone (2-DCB) in ground beef irradiated by low-energy X-rays and gamma rays. Beef patties were irradiated by low-energy X-rays and gamma rays (Cs-137) at 3 targeted absorbed doses of 1.5, 3.0, and 5.0 kGy. The samples were extracted with n-hexane using a Soxhlet apparatus, and the 2-DCB concentration was determined with gas chromatography-mass spectrometry. The 2-DCB concentration increased linearly (P irradiation dose for gamma-ray and low-energy X-ray irradiated patties. There was no significant difference in 2-DCB concentration between gamma-ray and low-energy X-ray irradiated patties (P > 0.05) at all targeted doses. © 2010 Institute of Food Technologists®

Response surface optimisation for activation of bentonite with microwave irradiation

Directory of Open Access Journals (Sweden)

Rožić Ljiljana S.

2011-01-01

Full Text Available In this study, the statistical design of the experimental method was applied on the acid activation process of bentonite with microwave irradiation. The influence of activation parameters (time, acid normality and microwave heating power on the selected process response of the activated bentonite samples was studied. The specific surface area was chosen for the process response, because the chemical, surface and structural properties of the activated clay determine and limit its potential applications. The relationship of various process parameters with the specific surface area of bentonite was examined. A mathematical model was developed using a second-order response surface model (RSM with a central composite design incorporating the above mentioned process parameters. The mathematical model developed helped in predicting the variation in specific surface area of activated bentonite with time (5-21 min, acid normality (2-7 N and microwave heating power (63-172 W. The calculated regression models were found to be statistically significant at the required range and presented little variability. Furthermore, high values of R2 (0.957 and R2 (adjusted (0.914 indicate a high dependence and correlation between the observed and the predicted values of the response. These high values also indicate that about 96% of the result of the total variation can be explained by this model. In addition, the model shows that increasing the time and acid normality improves the textural properties of bentonites, resulting in increased specific surface area. This model also can be useful for setting an optimum value of the activation parameters for achieving the maximum specific surface area. An optimum specific surface area of 142 m2g-1 was achieved with an acid normality of 5.2 N, activation time of 7.38 min and microwave power of 117 W. Acid activation of bentonite was found to occur faster with microwave irradiation than with conventional heating. Microwave

Influence of Irradiation Time on properties of CdS Nanoparticles Synthesized using Microwave Irradiation

International Nuclear Information System (INIS)

Nayereh Soltani; Elias SSaion; Maryam Erfani; Mohd Zobir Hussein; Robiah Yunus

2011-01-01

Different sizes of cadmium sulfide nanoparticles which exhibit obvious quantum confinement effect have been synthesized of cadmium chloride and thioacetamide through the simple and rapid microwave method. The properties of these CdS nanoparticles were examined with varying irradiation time from 10 to 40 min using a pulse regime. The obtained CdS particles were characterized by X-ray diffraction (XRD), transition electron microscopy (TEM) and UV-visible (UV-Vis) spectroscopy. The effects of irradiation time on the size, degree of crystallinity, yield of reaction and optical band gap of CdS nanoparticles are investigated. (author)

Controlled synthesis of novel octapod platinum nanocrystals under microwave irradiation

International Nuclear Information System (INIS)

Dai, Lei; Chi, Quan; Zhao, Yanxi; Liu, Hanfan; Zhou, Zhongqiang; Li, Jinlin; Huang, Tao

2014-01-01

Graphical abstract: Under microwave irradiation, novel octapod Pt nanocrystals were synthesized by reducing H 2 PtCl 6 in TEG with PVP as a stabilizer. The as-prepared Pt nanocrystals displayed a unique octapod nanostructure with five little mastoids in each concave center. The use of KI was crucial to the formation of novel Pt octapods. Novel Octapod Platinum Nanocrystals. - Highlights: • A novel octapod Pt nanocrystals different from the common octapod were obtained. • The use of KI was crucial to the formation of the novel Pt octapods. • Microwave was readily employed in controlled synthesis of the novel Pt octapods. - Abstract: Microwave was employed in the shape-controlled synthesis of Pt nanoparticles. Novel octapod Pt nanocrystals enclosed with (1 1 1) facets were readily synthesized with H 2 PtCl 6 as a precursor, tetraethylene glycol (TEG) as both a solvent and a reducing agent, polyvinylpyrrolidone (PVP) as a stabilizer in the presence of an appropriate amount of KI under microwave irradiation for 140 s. The as-prepared Pt nanocrystals displayed a unique octapod nanostructure with five little mastoids in each concave center and exhibited higher electrocatalytic activity than commercial Pt black in the electro-oxidations of methanol and formic acid. The results demonstrated that the use of KI was crucial to the formation of Pt octapods. KI determined the formation of the novel octapod Pt nanocrystals by tuning up the reduction kinetics and adsorbing on the surfaces of growing Pt nanoparticles. The optimum molar ratio of H 2 PtCl 6 /KI/PVP was 1/30/45

Efficacy of Microwave Disinfection on Moist and Dry Dental Stone Casts with Different Irradiation Times

Directory of Open Access Journals (Sweden)

Mahmood Robati Anaraki

2015-07-01

Full Text Available Objectives: Dental practice contains the use of instruments and multiuse items that should be sterilized or disinfected properly. The aim of the current study was to investigate the effect of microwave irradiation on dental stone cast disinfection in moist and dry condition. Materials and Methods: In this in vitro study, 76 stone casts were prepared by a sterile method. The casts were contaminated by Pseudomonas aeruginosa (ATCC 9027, Staphylococcus aureus (ATCC 6538, Enterococcus faecalis (ATCC 29212 as well as Candida albicans (ATCC 10231. Half the samples were dried for two hours and the other half was studied while still moist. The samples were irradiated by a household microwave at 600 W for 3, 5 and 7 minutes. The microorganisms on the samples were extracted by immersion in tryptic soy broth and .001 ml of that was cultured in nutrient agar media, incubated overnight and counted and recorded as colony forming unit per milliliter (CFU/mL. Results: The findings showed that microorganisms reduced to 4.87 logarithm of CFU/mL value on dental cast within seven minutes in comparison with positive control. Although microbial count reduction was observed as a result of exposure time increase, comparison between moist and dried samples showed no significant difference. Conclusions: Seven-minute microwave irradiation at 600 W can effectively reduce the microbial load of dental stone casts. Wetting the casts does not seem to alter the efficacy of irradiation.   Keywords: Microwave Disinfection; Dental Stone Casts; Irradiation Times

Spin dynamics in the single molecule magnet Ni4 under microwave irradiation

Science.gov (United States)

de Loubens, Gregoire

2009-03-01

Quantum mechanical effects such as quantum tunneling of magnetization (QTM) and quantum phase interference have been intensively studied in single molecule magnets (SMMs). These materials have also been suggested as candidates for qubits and are promising for molecular spintronics. Understanding decoherence and energy relaxation mechanisms in SMMs is then both of fundamental interest and important for the use of SMMs in applications. Interestingly, the single-spin relaxation rate due to direct process of a SMM embedded in an elastic medium can be derived without any unknown coupling constant [1]. Moreover, nontrivial relaxation mechanisms are expected from collective effects in SMM single crystals, such as phonon superradiance or phonon bottleneck. In order to investigate the spin relaxation between the two lowest lying spin-states of the S=4 single molecule magnet Ni4, we have developed an integrated sensor that combines a microstrip resonator and micro-Hall effect magnetometer on a chip [2]. This sensor enables both real time studies of magnetization dynamics under pulse irradiation as well as simultaneous measurements of the absorbed power and magnetization changes under continuous microwave irradiation. The latter technique permits the study of small deviations from equilibrium under steady state conditions, i.e. small amplitude cw microwave irradiation. This has been used to determine the energy relaxation rate of a Ni4 single crystal as a function of temperature at two frequencies, 10 and 27.8 GHz. A strong temperature dependence is observed below 1.5 K, which is not consistent with a direct spin-phonon relaxation process. The data instead suggest that the spin relaxation is dominated by a phonon bottleneck at low temperatures and occurs by an Orbach process involving excited spin-levels at higher temperatures [3]. Experimental results will be compared with detailed calculations of the relaxation rate using the density matrix equation with the relaxation

Effect of Microwave Irradiation on the Condensation of 6-Substituted 3-Formylchromones with Some Five-membered Heterocyclic Compounds

Directory of Open Access Journals (Sweden)

Nada Pronayova

2000-02-01

Full Text Available Different types of 3-substituted 4H-4-oxobenzopyrans were prepared by microwave irradiation as well as by a classical method. The beneficial effect of microwave irradiation on the aldol condensation of 3-formylchromones with 2-imino-1-methylimidazolidine-4-one (creatinine, 2-thioxoimidazolidine-4-one (thiohydantoin and 2-ethyl-2-thioxothiazolidin-4-one (3-ethylrhodanine in different reaction media is described. Our results show that the effect of microwave irradiation on the reactions studied was a shortening of the reaction times and a smooth increase in the yields. The subsequent reactions of the product with some nucleophiles are discussed. The structure of the products was proven by elemental analysis, IR and NMR spectra.

Immunocytochemistry of formalin-fixed human brain tissues: microwave irradiation of free-floating sections.

Science.gov (United States)

Shiurba, R A; Spooner, E T; Ishiguro, K; Takahashi, M; Yoshida, R; Wheelock, T R; Imahori, K; Cataldo, A M; Nixon, R A

1998-01-01

Formalin fixation, the chemical process in which formaldehyde binds to cells and tissues, is widely used to preserve human brain specimens from autolytic decomposition. Ultrastructure of cellular and mitochondrial membranes is markedly altered by vesiculation, but this does not interfere with diagnostic evaluation of neurohistology by light microscopy. Serious difficulties are encountered, however, when immunocytochemical staining is attempted. Antigens that are immunoreactive in unfixed frozen sections and protein extracts appear to be concealed or destroyed in formalin-fixed tissues. In dilute aqueous solution, formaldehyde is in equilibrium with methylene glycol and its polymeric hydrates, the balance by far in favor of methylene glyco. Carbonylic formaldehyde is a reactive electrophilic species well known for crosslinking functional groups in tissue proteins, nucleic acids, and polysaccharides. Some of its methylene crosslinks are readily hydrolyzed. Others are stable and irreversible. During immunostaining reactions, intra- and inter-molecular links between macromolecules limit antibody permeation of tissue sections, alter protein secondary structure, and reduce accessibility of antigenic determinants . Accordingly, immunoreactivity is diminished for many antigens. Tissues are rapidly penetrated by methylene glycol, but formaldehyde binding to cellular constituents is relatively slow, increasing progressively until equilibrium is reached. In addition, prolonged storage in formalin may result in acidification of human brain specimens. Low pH favors dissociation of methylene glycol into formaldehyde, further reducing both classical staining and antigen detectability. Various procedures have been devised to counter the antigen masking effects of formaldehyde. Examples include pretreatment of tissue sections with proteases, formic acid, or ultrasound. Recently, heating of mounted sections in ionic salt solution by microwave energy was found to restore many

The effect of non-contact heating (microwave irradiation) and contact heating (annealing process) on properties and performance of polyethersulfone nanofiltration membranes

International Nuclear Information System (INIS)

Mansourpanah, Y.; Madaeni, S.S.; Rahimpour, A.; Farhadian, A.

2009-01-01

In this work the effect of microwave irradiation on morphology and performance of polyethersulfone (PES) membranes was investigated. The membranes were prepared with 20 wt.% of PES by phase inversion method. N,N-dimethylformamide (DMF) and mixture of water and ethyl alcohol (90/10 vol.%) were employed as solvent and coagulant respectively. Polyvinylpirrolidone (PVP) with the concentration of 2 wt.% was selected as pore former. The effects of irradiation time (10, 30, 60, 90, 120 s) and microwave power (180, 360, 720 and 900 W) on structure and performance of membranes were studied. Increasing the irradiation time and power caused variation in permeate flux and ion rejection. Moreover, the effects of annealing processes (60, 70, 80 deg. C) were studied. Transmembrane pressure was selected around 1.5 MPa for all experiments. Scanning electron microscope (SEM) and atomic force microscope (AFM) were employed to describe the surface morphology of the prepared membranes. The effect of microwave irradiation time in different power revealed alterations in membrane surface morphology and AFM images represented that surface parameters (such as surface roughness) have been changed. The membrane exhibited moderate rejection (47%) and low permeate flux (4.5 kg/m 2 h) at 80 deg. C for NaCl solution. The SEM images indicate that the dense skin layer is formed at 80 deg. C annealing.

Bone-like hydroxyapatite precipitated from 10×SBF-like solution by microwave irradiation

International Nuclear Information System (INIS)

Tolga Demirtaş, T.; Kaynak, Gökçe; Gümüşderelioğlu, Menemşe

2015-01-01

Microwave-assisted methods have been frequently used in many processes owing to their numerous advantages such as performing fast, efficient and homogenous processes and reducing side reactions. In view of these benefits, in this study it was purposed to produce bone-like hydroxyapatite (HA) by inducing biomimetic process with microwave-irradiation. This is why, concentrated body fluid (SBF) i.e. 10×SBF-like solution was used and it was precipitated in different microwave powers i.e. 90 W, 360 W, 600 W, and 1200 W and in different exposure times. For comparison, precipitation process was also carried out at room temperature for 6 h and at 80 °C for 1 h. The obtained HA structures were characterized by appropriate instrumental techniques. As a result, microwave-induced precipitation at 600 W for 9 times 30 s was determined as the optimum condition for the production of HA which has similar properties to the cortical bone. At this condition, B-type HA with 9.22% (wt.) carbonate content, 1.61 Ca/P molar ratio and amorphous structure was obtained easily, rapidly and efficiently. So, this is the first time microwave technology has been used to precipitate HA from SBF solution. - Highlights: • Simple, rapid and efficient method was developed to produce bone-like HA. • Microwave radiation and biomimetic approach via 10×SBF-like solution were combined. • Microwave irradiation at 600 W for 9 × 30 s was determined as the optimum condition. • B-type HA (carbonate content: 9.22%; 1.61 Ca/P:1.61; amorph) was produced. • This method may be employed for the effective HA coating of 3D bone scaffolds

Bone-like hydroxyapatite precipitated from 10×SBF-like solution by microwave irradiation

Energy Technology Data Exchange (ETDEWEB)

Tolga Demirtaş, T.; Kaynak, Gökçe [Bioengineering Engineering Department, Hacettepe University, 06800 Beytepe, Ankara (Turkey); Gümüşderelioğlu, Menemşe, E-mail: menemse@hacettepe.edu.tr [Bioengineering Engineering Department, Hacettepe University, 06800 Beytepe, Ankara (Turkey); Chemical Engineering Department, Hacettepe University, 06800 Beytepe, Ankara (Turkey)

2015-04-01

Microwave-assisted methods have been frequently used in many processes owing to their numerous advantages such as performing fast, efficient and homogenous processes and reducing side reactions. In view of these benefits, in this study it was purposed to produce bone-like hydroxyapatite (HA) by inducing biomimetic process with microwave-irradiation. This is why, concentrated body fluid (SBF) i.e. 10×SBF-like solution was used and it was precipitated in different microwave powers i.e. 90 W, 360 W, 600 W, and 1200 W and in different exposure times. For comparison, precipitation process was also carried out at room temperature for 6 h and at 80 °C for 1 h. The obtained HA structures were characterized by appropriate instrumental techniques. As a result, microwave-induced precipitation at 600 W for 9 times 30 s was determined as the optimum condition for the production of HA which has similar properties to the cortical bone. At this condition, B-type HA with 9.22% (wt.) carbonate content, 1.61 Ca/P molar ratio and amorphous structure was obtained easily, rapidly and efficiently. So, this is the first time microwave technology has been used to precipitate HA from SBF solution. - Highlights: • Simple, rapid and efficient method was developed to produce bone-like HA. • Microwave radiation and biomimetic approach via 10×SBF-like solution were combined. • Microwave irradiation at 600 W for 9 × 30 s was determined as the optimum condition. • B-type HA (carbonate content: 9.22%; 1.61 Ca/P:1.61; amorph) was produced. • This method may be employed for the effective HA coating of 3D bone scaffolds.

Effect of low level prenatal X-irradiation on postnatal growth in the Wistar rat

International Nuclear Information System (INIS)

Jensh, R.P.; Brent, R.L.

1988-01-01

Forty-five pregnant Wistar strain rats were exposed to 0.0, 0.4, 0.6, or 0.8 Gy X-radiation on the 9th or 17th day of gestation to determined if prenatal X-irradiation would result in alterations in postnatal growth or growth rate. The mothers delivered their offspring, and the litters were reduced to a maximum of eight per litter on the second postnatal day. The 336 offspring were weighed weekly from day 3 until day 86, at which time they were killed, an autopsy was performed, and selected organs were removed and weighed. Postnatal growth rates did not differ significantly in irradiated offspring compared to sham irradiated animals. Irradiation on the 9th day, at any of the 3 dosage levels, did not result in significant differences in weekly weight. Weekly weight remained significantly lower due to irradiation on the 17th day of gestation. The gonadal weight ratio was significantly reduced in males irradiated on the 9th day. There were not other statistically significant changes in organ weight or organ/body weight ratios due to these levels of prenatal X-irradiation on the 9th or 17th day of pregnancy. These results indicate that low level prenatal X-irradiation, on the 17th day of rat gestation, causes prenatal growth retardation, evident at birth, which is not recuperable postnatally. Exposure to x-radiation at this time, however, does not affect the rate at which offspring grow during postnatal life. Offspring are smaller because they never fully recover from the original radiation-induced prenatal growth retardation

Influence of irradiated with microwaves on color of potato maltodextrines with differential value of dextrose equivalent (DE)

International Nuclear Information System (INIS)

Przetaczek, I.; Roznowski, J.; Fortuna, T.

2009-01-01

Color is a dominant feature of groceries, therefore the objective of the study was to investigate the effect of irradiated with microwaves on color of potato maltodextrines. The initial material for the study was commercial maltodextrines with differential DE. All of maltodextrines were irradiated with microwaves (440 W or 800 W), then were investigated range of color changing. The color of the samples was measured using a spectrophotometer X-Rite incorporated (USA), type X-Rite Color i5 fitted with a 10 mm diameter and standard observer 10 degrees (CIE 1964). Maltodextrines color was measured in CIELAB and SPEX system using illuminant D65. In general, the value of Dextrose Equivalent and power microwaves influenced on range of color changing. Irradiation at 800 W caused to rise of value of units a and b for all of maltodextrines and reduced lightness

Effect of modified graphene and microwave irradiation on the mechanical and thermal properties of poly(styrene-co-methyl methacrylate)/graphene nanocomposites

KAUST Repository

Zubair, Mukarram

2014-08-04

The effect of modified graphene (MG) and microwave irradiation on the interaction between graphene (G) and poly(styrene-co-methyl meth acrylate) [P(S-co-MMA)] polymer matrix has been studied in this article. Modification of graphene was performed using nitric acid. P(S-co-MMA) polymer was blended via melt blending with pristine and MG. The resultant nanocomposites were irradiated under microwave at three different time intervals (5, 10, and 20 min). Compared to pristine graphene, MG showed improved interaction with P(S-co-MMA) polymer (P) after melt mixing and microwave irradiation. The mechanism of improved dispersion and interaction of modified graphene with P(S-co-MMA) polymer matrix during melt mixing and microwave irradiation is due to the presence of oxygen functionalities on the surface of MG as confirmed from Fourier transform infrared spectroscopy. The formation of defects on modified graphene and free radicals on P(S-co-MMA) polymer chains after irradiation as explained by Raman spectroscopy and X-Ray diffraction studies. The nanocomposites with 0.1 wt% G and MG have shown a 26% and 38% increase in storage modulus. After irradiation (10 min), the storage modulus further improved to 11.9% and 27.6% of nanocomposites. The glass transition temperature of nanocomposites also improved considerably after melt mixing and microwave irradiation (but only for polymer MG nanocomposite). However, at higher irradiation time (20 min), degradation of polymer nanocomposites occurred. State of creation of crosslink network after 10 min of irradiation and degradation after 20 min of irradiation of nanocomposites was confirmed from SEM studies. Copyright © 2014 John Wiley & Sons, Ltd.

Microwave radiation mechanism in a pulse-laser-irradiated Cu foil target revisited

International Nuclear Information System (INIS)

Chen Ziyu; Li Jianfeng; Li Jun; Peng Qixian

2011-01-01

The microwave radiation mechanism in a Cu-based foil target irradiated by an intense laser pulse has been investigated. Microwave emission in the frequency range 0.5-4 GHz has been observed from a 200 ps laser pulse of intensity about 10 12 W cm -2 normally incident on the target surface. The total microwave power and energy emitted from the interaction were found to be about 0.4 W and 2 nJ, respectively, corresponding to an efficiency of coupling laser energy to microwave energy of 2x10 -8 . The result agrees well with quadrupole radiation calculated based on a circuit model of a laser plasma, which indicates that the radiative process can be explained by magnetic dipole or electric quadrupole radiation from the laser-produced symmetric poloidal current distribution at the plasma-target interface.

Microwave radiation mechanism in a pulse-laser-irradiated Cu foil target revisited

Energy Technology Data Exchange (ETDEWEB)

Chen Ziyu; Li Jianfeng; Li Jun; Peng Qixian, E-mail: ziyuch@gmail.com [Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621900 (China)

2011-05-01

The microwave radiation mechanism in a Cu-based foil target irradiated by an intense laser pulse has been investigated. Microwave emission in the frequency range 0.5-4 GHz has been observed from a 200 ps laser pulse of intensity about 10{sup 12} W cm{sup -2} normally incident on the target surface. The total microwave power and energy emitted from the interaction were found to be about 0.4 W and 2 nJ, respectively, corresponding to an efficiency of coupling laser energy to microwave energy of 2x10{sup -8}. The result agrees well with quadrupole radiation calculated based on a circuit model of a laser plasma, which indicates that the radiative process can be explained by magnetic dipole or electric quadrupole radiation from the laser-produced symmetric poloidal current distribution at the plasma-target interface.

Microwave Irradiation Assisted Preparation of Chitosan Composite Microsphere for Dye Adsorption

Directory of Open Access Journals (Sweden)

Xiaoyu Chen

2017-01-01

Full Text Available Chitosan-activated carbon composite microspheres were prepared by emulsion cross-linking method and its adsorption properties for methyl orange were studied. Chitosan solution was mixed with activated carbon powder and then chitosan was cross-linked by epichlorohydrin under microwave irradiation. SEM photos show that the composite microspheres have diameters of 200–400 μm and activated carbon powder dispersed on the surface of composite microsphere. FTIR spectrum indicates chitosan is successfully cross-linked. Microwave irradiation can effectively shorten the cross-linking time. Composite microspheres have enhanced dye adsorption capacity for methyl orange compared to chitosan microspheres. Kinetic studies showed that the adsorption followed a pseudo-second-order model. Isotherm studies show that the isotherm adsorption equilibrium is better described by Freundlich isotherm. Regeneration results show that adsorption capacity of composite microsphere decreased about 5.51% after being reused for three times. These results indicated that chitosan-activated carbon composite microsphere has potential application in the removal of dye from wastewaters.

Oligoquinolines under Solvent-free Microwave Irradiation

Energy Technology Data Exchange (ETDEWEB)

Park, Kwi-Jeon; Kwon, Tae-Woo [Kyungsung University, Busan (Korea, Republic of)

2015-01-15

Quinolines are thermally stable and can be used as an excellent n-type semiconducting materials. Since quinolines are also known to be electron acceptor molecules, combination of various electron donor building blocks can be utilized in photonic and electronic organic light-emitting diode (OLED) applications. For example, donor.acceptor systems with phenothiazine (or carbazole) molecules as electron donors and the phenylquinoline group as an electron acceptor provide an efficient approach for the design of new materials exhibiting highly efficient charge-transfer photophysics and electroluminescence in OLEDs. We have described the Friedlander quinoline synthesis between aminobenzophenones and symmetrical diacetyl compounds having phenothiazine, carbazole, biphenyl, and phenyl moieties under solvent-free microwave irradiation in 12.98% isolated yields.

Effects of lignocellulosic composition and microwave power level on the gaseous product of microwave pyrolysis

International Nuclear Information System (INIS)

Huang, Yu-Fong; Chiueh, Pei-Te; Kuan, Wen-Hui; Lo, Shang-Lien

2015-01-01

Agricultural residues are abundant resources to produce renewable energy and valuable chemicals. This study focused on the effects of lignocellulosic composition and microwave power level on the gaseous product of microwave pyrolysis of agricultural residues. When agricultural residues were under microwave radiation within 10 min, the maximum temperatures of approximately 320, 420, and 530 °C were achieved at the microwave power levels of 300, 400, and 500 W, respectively. Gas yield increased with increasing microwave power level, whereas solid and liquid yields decreased. Besides, gaseous products with higher H 2 content and higher calorific values can be obtained at higher microwave power levels. In addition to microwave power level, lignocellulosic composition was also an important factor. H 2 and CO 2 yields increased with increasing hemicellulose content, whereas CH 4 and CO yields increased with increasing cellulose content. Four empirical equations were derived to present the contributions of lignocellulosic materials to the yields of gaseous components. - Highlights: • About 530 °C was reached within 10 min at a microwave power level of 500 W. • Gas yield increased with increasing microwave power level. • A high correlation between hemicellulose content and either H 2 or CO 2 yield. • A high correlation between cellulose content and either CH 4 or CO yield. • Empirical equations depict contribution of lignocellulosic content to gas yield

Biodiesel production from lipids in wet microalgae with microwave irradiation and bio-crude production from algal residue through hydrothermal liquefaction.

Science.gov (United States)

Cheng, Jun; Huang, Rui; Yu, Tao; Li, Tao; Zhou, Junhu; Cen, Kefa

2014-01-01

A cogeneration process of biodiesel and bio-crude was proposed to make full use of wet microalgae biomass. High-grade biodiesel was first produced from lipids in wet microalgae through extraction and transesterification with microwave irradiation. Then, low-grade bio-crude was produced from proteins and carbohydrates in the algal residue through hydrothermal liquefaction. The total yield (40.19%) and the total energy recovery (67.73%) of the cogenerated biodiesel and bio-crude were almost equal to those of the bio-oil obtained from raw microalgae through direct hydrothermal liquefaction. Upon microwave irradiation, proteins were partially hydrolyzed and the hydrolysates were apt for deaminization under the hydrothermal condition of the algal residue. Hence, the total remaining nitrogen (16.02%) in the cogenerated biodiesel and bio-crude was lower than that (27.06%) in the bio-oil. The cogeneration process prevented lipids and proteins from reacting to produce low-grade amides and other long-chain nitrogen compounds during the direct hydrothermal liquefaction of microalgae. Copyright © 2013 Elsevier Ltd. All rights reserved.

Cycloadditions of ketene acetals under microwave irradiation in solvent-free conditions

International Nuclear Information System (INIS)

Diaz-Ortiz, A.; Diez-Barra, E.; La Hoz, A. De; Prieto, P.; Moreno, A.

1994-01-01

When subjected to microwave irradiation ketene acetals undergo 1.3-dipolar and hetero-Diels-Alder cycloadditions within 5-12 min to give excellent yields of easily purified heterocyclic products. This efficient and rapid synthesis has the advantage of employing milder reaction conditions than those of classical thermal heating. (author)

Photonic microwave signals with zeptosecond-level absolute timing noise

Science.gov (United States)

Xie, Xiaopeng; Bouchand, Romain; Nicolodi, Daniele; Giunta, Michele; Hänsel, Wolfgang; Lezius, Matthias; Joshi, Abhay; Datta, Shubhashish; Alexandre, Christophe; Lours, Michel; Tremblin, Pierre-Alain; Santarelli, Giorgio; Holzwarth, Ronald; Le Coq, Yann

2017-01-01

Photonic synthesis of radiofrequency (RF) waveforms revived the quest for unrivalled microwave purity because of its ability to convey the benefits of optics to the microwave world. In this work, we perform a high-fidelity transfer of frequency stability between an optical reference and a microwave signal via a low-noise fibre-based frequency comb and cutting-edge photodetection techniques. We demonstrate the generation of the purest microwave signal with a fractional frequency stability below 6.5 × 10-16 at 1 s and a timing noise floor below 41 zs Hz-1/2 (phase noise below -173 dBc Hz-1 for a 12 GHz carrier). This outperforms existing sources and promises a new era for state-of-the-art microwave generation. The characterization is achieved through a heterodyne cross-correlation scheme with the lowermost detection noise. This unprecedented level of purity can impact domains such as radar systems, telecommunications and time-frequency metrology. The measurement methods developed here can benefit the characterization of a broad range of signals.

The separated electric and magnetic field responses of luminescent bacteria exposed to pulsed microwave irradiation

Energy Technology Data Exchange (ETDEWEB)

Williams, Catrin F., E-mail: williamscf@cardiff.ac.uk [School of Engineering, Cardiff University, Queen' s Buildings, Newport Road, Cardiff, CF24 3AA Wales (United Kingdom); School of Biosciences, Cardiff University, Main Building, Cathays Park, Cardiff, CF10 3AT Wales (United Kingdom); Geroni, Gilles M.; Pirog, Antoine; Lees, Jonathan; Porch, Adrian [School of Engineering, Cardiff University, Queen' s Buildings, Newport Road, Cardiff, CF24 3AA Wales (United Kingdom); Lloyd, David [School of Biosciences, Cardiff University, Main Building, Cathays Park, Cardiff, CF10 3AT Wales (United Kingdom)

2016-08-29

Electromagnetic fields (EMFs) are ubiquitous in the digital world we inhabit, with microwave and millimetre wave sources of non-ionizing radiation employed extensively in electronics and communications, e.g., in mobile phones and Wi-Fi. Indeed, the advent of 5G systems and the “internet of things” is likely to lead to massive densification of wireless networks. Whilst the thermal effects of EMFs on biological systems are well characterised, their putative non-thermal effects remain a controversial subject. Here, we use the bioluminescent marine bacterium, Vibrio fischeri, to monitor the effects of pulsed microwave electromagnetic fields, of nominal frequency 2.5 GHz, on light emission. Separated electric and magnetic field effects were investigated using a resonant microwave cavity, within which the maxima of each field are separated. For pulsed electric field exposure, the bacteria gave reproducible responses and recovery in light emission. At the lowest pulsed duty cycle (1.25%) and after short durations (100 ms) of exposure to the electric field at power levels of 4.5 W rms, we observed an initial stimulation of bioluminescence, whereas successive microwave pulses became inhibitory. Much of this behaviour is due to thermal effects, as the bacterial light output is very sensitive to the local temperature. Conversely, magnetic field exposure gave no measurable short-term responses even at the highest power levels of 32 W rms. Thus, we were able to detect, de-convolute, and evaluate independently the effects of separated electric and magnetic fields on exposure of a luminescent biological system to microwave irradiation.

The separated electric and magnetic field responses of luminescent bacteria exposed to pulsed microwave irradiation

Science.gov (United States)

Williams, Catrin F.; Geroni, Gilles M.; Pirog, Antoine; Lloyd, David; Lees, Jonathan; Porch, Adrian

2016-08-01

Electromagnetic fields (EMFs) are ubiquitous in the digital world we inhabit, with microwave and millimetre wave sources of non-ionizing radiation employed extensively in electronics and communications, e.g., in mobile phones and Wi-Fi. Indeed, the advent of 5G systems and the "internet of things" is likely to lead to massive densification of wireless networks. Whilst the thermal effects of EMFs on biological systems are well characterised, their putative non-thermal effects remain a controversial subject. Here, we use the bioluminescent marine bacterium, Vibrio fischeri, to monitor the effects of pulsed microwave electromagnetic fields, of nominal frequency 2.5 GHz, on light emission. Separated electric and magnetic field effects were investigated using a resonant microwave cavity, within which the maxima of each field are separated. For pulsed electric field exposure, the bacteria gave reproducible responses and recovery in light emission. At the lowest pulsed duty cycle (1.25%) and after short durations (100 ms) of exposure to the electric field at power levels of 4.5 W rms, we observed an initial stimulation of bioluminescence, whereas successive microwave pulses became inhibitory. Much of this behaviour is due to thermal effects, as the bacterial light output is very sensitive to the local temperature. Conversely, magnetic field exposure gave no measurable short-term responses even at the highest power levels of 32 W rms. Thus, we were able to detect, de-convolute, and evaluate independently the effects of separated electric and magnetic fields on exposure of a luminescent biological system to microwave irradiation.

The separated electric and magnetic field responses of luminescent bacteria exposed to pulsed microwave irradiation

International Nuclear Information System (INIS)

Williams, Catrin F.; Geroni, Gilles M.; Pirog, Antoine; Lees, Jonathan; Porch, Adrian; Lloyd, David

2016-01-01

Electromagnetic fields (EMFs) are ubiquitous in the digital world we inhabit, with microwave and millimetre wave sources of non-ionizing radiation employed extensively in electronics and communications, e.g., in mobile phones and Wi-Fi. Indeed, the advent of 5G systems and the “internet of things” is likely to lead to massive densification of wireless networks. Whilst the thermal effects of EMFs on biological systems are well characterised, their putative non-thermal effects remain a controversial subject. Here, we use the bioluminescent marine bacterium, Vibrio fischeri, to monitor the effects of pulsed microwave electromagnetic fields, of nominal frequency 2.5 GHz, on light emission. Separated electric and magnetic field effects were investigated using a resonant microwave cavity, within which the maxima of each field are separated. For pulsed electric field exposure, the bacteria gave reproducible responses and recovery in light emission. At the lowest pulsed duty cycle (1.25%) and after short durations (100 ms) of exposure to the electric field at power levels of 4.5 W rms, we observed an initial stimulation of bioluminescence, whereas successive microwave pulses became inhibitory. Much of this behaviour is due to thermal effects, as the bacterial light output is very sensitive to the local temperature. Conversely, magnetic field exposure gave no measurable short-term responses even at the highest power levels of 32 W rms. Thus, we were able to detect, de-convolute, and evaluate independently the effects of separated electric and magnetic fields on exposure of a luminescent biological system to microwave irradiation.

Improved synthesis of 1,3,4-thiadiazolium-2-phenylamines using microwave and ultrasound irradiation and investigation of their cytotoxic activity

Energy Technology Data Exchange (ETDEWEB)

Reis, Camilla Moretto dos; Miranda, Amanda Fraga; Echevarria, Aurea, E-mail: echevarr@ufrrj.b [Universidade Federal Rural do Rio de Janeiro (DQ/ICE/UFRRJ), Seropedica, RJ (Brazil). Inst. de Ciencias Exatas. Dept. de Quimica; Echevarria-Lima, Juliana [Universidade Federal do Rio de Janeiro (DI/IMPG/UFRJ), RJ (Brazil). Inst. de Microbiologia Paulo de Goes. Dept. de Imunologia

2011-07-01

A new and efficient synthesis of eight 1,3,4-thiadiazolium-2-phenylamine derivatives (1-8, where 8 is novel in the literature) was performed using thionyl chloride or trimethylsilyl chloride as catalysts under microwave or ultrasound irradiation. The target compounds were obtained in good yields and remarkably short times, 5 min under microwave irradiation and 10 min under ultrasound irradiation, where compared to traditional methodology (24 to 48 h at room temperature standing). The best yields were obtained using the microwave irradiation and, in general way, using thionyl chloride instead trimethylsilyl chloride. The cytotoxicity against K562 human leukemia and Daudi lymphoma lines was evaluated and showed promising results from the 4-phenyl-5-(4'-nitro-styryl)-1,3,4-thiadiazolium-2-phenylamine chloride derivative. (author)

The influences of microwave irradiation and polyol precursor pH on Cu/AC catalyst and its CO oxidation performance

Science.gov (United States)

Chuang, Kui-Hao; Shih, Kaimin; Wey, Ming-Yen

2012-10-01

This study evaluated the effects of microwave irradiation parameters and the pH of the polyol precursor on the morphological features and catalytic performances of Cu/activated carbon (AC) catalysts. Experimental results of carbon monoxide (CO) oxidation indicated that the highest catalytic activity is achieved when the Cu/AC catalyst is prepared with microwave irradiation at 700 W for 60 s. Scanning electron microscopy revealed the presence of beneficial small copper aciculae on the Cu/AC catalyst under such a microwave irradiation scheme. Further investigation of operational parameters found that the performance of Cu/AC catalysts is enhanced by adopting a pH = 12 polyol precursor solution. With the observation that small cube copper ( 16 nm) aggregates form when a pH = 12 polyol precursor solution is used, this study also demonstrated the importance of controlling the morphology of metal nanoparticles on Cu/AC catalysts when using the microwave-assisted polyol method.

The influences of microwave irradiation and polyol precursor pH on Cu/AC catalyst and its CO oxidation performance

International Nuclear Information System (INIS)

Chuang, Kui-Hao; Shih, Kaimin; Wey, Ming-Yen

2012-01-01

This study evaluated the effects of microwave irradiation parameters and the pH of the polyol precursor on the morphological features and catalytic performances of Cu/activated carbon (AC) catalysts. Experimental results of carbon monoxide (CO) oxidation indicated that the highest catalytic activity is achieved when the Cu/AC catalyst is prepared with microwave irradiation at 700 W for 60 s. Scanning electron microscopy revealed the presence of beneficial small copper aciculae on the Cu/AC catalyst under such a microwave irradiation scheme. Further investigation of operational parameters found that the performance of Cu/AC catalysts is enhanced by adopting a pH = 12 polyol precursor solution. With the observation that small cube copper (∼16 nm) aggregates form when a pH = 12 polyol precursor solution is used, this study also demonstrated the importance of controlling the morphology of metal nanoparticles on Cu/AC catalysts when using the microwave-assisted polyol method.

Resistive switching characteristics of solution-processed Al-Zn-Sn-O films annealed by microwave irradiation

Science.gov (United States)

Kim, Tae-Wan; Baek, Il-Jin; Cho, Won-Ju

2018-02-01

In this study, we employed microwave irradiation (MWI) at low temperature in the fabrication of solution-processed AlZnSnO (AZTO) resistive random access memory (ReRAM) devices with a structure of Ti/AZTO/Pt and compared the memory characteristics with the conventional thermal annealing (CTA) process. Typical bipolar resistance switching (BRS) behavior was observed in AZTO ReRAM devices treated with as-deposited (as-dep), CTA and MWI. In the low resistance state, the Ohmic conduction mechanism describes the dominant conduction of these devices. On the other hand, the trap-controlled space charge limited conduction (SCLC) mechanism predominates in the high resistance state. The AZTO ReRAM devices processed with MWI showed larger memory windows, uniform distribution of resistance state and operating voltage, stable DC durability (>103 cycles) and stable retention characteristics (>104 s). In addition, the AZTO ReRAM devices treated with MWI exhibited multistage storage characteristics by modulating the amplitude of the reset bias, and eight distinct resistance levels were obtained with stable retention capability.

A microwave-irradiated Streptococcus agalactiae vaccine provides partial protection against experimental challenge in Nile tilapia, Oreochromis niloticus

Science.gov (United States)

Microwave irradiation, as opposed to formalin exposure, has not routinely been used in the preparation of killed vaccines despite the advantages of decreased chemical toxicity, ability to kill cells quickly, ease of completion requiring only a standard microwave, and potential increased protein cons...

Paramecium tetraurelia growth stimulation under low-level chronic irradiation: investigations on a possible mechanism

International Nuclear Information System (INIS)

Croute, F.; Soleilhavoup, J.P.; Vidal, S.; Dupouy, D.; Planel, H.

1982-01-01

Experiments were carried out to demonstrate the effects of low-level chronic irradiation on Paramecium tetraurelia proliferation. Biological effects were strongly dependent on the bacterial density of culture medium and more exactly on the catalase content of the medium. Significant growth stimulation was found under 60 Co chronic irradiation at a dose rate of 2 rad/year when paramecia were grown in a medium containing a high bacterial concentration (2.5 x 10 2 cells/m) or supplemented with catalase (300 U/ml). In a medium with a low bacterial density (1 x 10 6 cell/ml) or supplemented with a catalase activity inhibitor, growth simulation was preceded by a transitory inhibiting effect which could be correlated with extracellularly radioproduced H 2 O 2 . H 2 O 2 addition appeared to be able to simulate the biological effects of chronic irradiation. A possible mechanism is discussed.We proposed that the stimulating effects were the result of intracellular enzymatic scavenging of radioproduced H 2 O 2

Peroxydisulfate initiated synthesis of potato starch-graft-poly(acrylonitrile under microwave irradiation

Directory of Open Access Journals (Sweden)

2007-01-01

Full Text Available Potato starch-graft-poly(acrylonitrile could be efficiently synthesized using small concentration of ammonium peroxydisulfate (0.0014M in aqueous medium under microwave irradiation. A representative microwave synthesized graft copolymer was characterized using Fourier Transform Infrared Spectroscopy, X-ray Diffraction, Scanning Electron Microscopy and Thermogravimetric Analysis. Under microwave conditions oxygen removal from the reaction vessel was not required and the graft copolymer was obtained in high yield using very small amount of ammonium peroxydisulfate, however using the same amount of ammonium peroxydisulfate (0.0014M on thermostatic water bath no grafting was observed up to 98°C (even in inert atmosphere. Raising the concentration of the initiator to 0.24 M resulted into 10% grafting at 50 °C but in inert atmosphere.The viscosity/shear stability of the grafted starch (aqueous solution and water/saline retention ability of the microwave synthesized graft copolymer were also studied and compared with that of the native potato starch.

Magnetically separable nanoferrite-anchored glutathione: Aqueous homocoupling of arylboronic acids under microwave irradiation

Science.gov (United States)

A highly active, stable and magnetically separable glutathione based organocatalyst provided good to excellent yields to symmetric biaryls in the homocoupling of arylboronic acids under microwave irradiation. Symmetrical biaryl motifs are present in a wide range of natural p...

Microwave-assisted degradation of acid orange using a conjugated polymer, polyaniline, as catalyst

Directory of Open Access Journals (Sweden)

Ufana Riaz

2014-01-01

Full Text Available Microwave-assisted photocatalytic degradation of dyes is one of the emerging technologies for waste water remediation. Microwave effectively accelerates photocatalytic degradation, when microwave electrodeless lamp (MEL substitutes traditional UV lamp as light source. This setup can be extremely simplified if MEL and photocatalyst can be replaced by a catalyst which can work under microwave irradiation in the absence of any light source. The present work reports for the first time degradation of acid orange 7 (AO under microwave irradiation using polyaniline (PANI as catalyst in the absence of any UV lamp as light source. The degradation/decolourization was carried out in neutral acidic and basic media and was monitored spectrophotometrically to evaluate the ability of microwave irradiation to degrade AO. Microwave irradiation showed excellent performance as it completely decolourizes AO dye solution in 10 min. With the advantages of low cost and rapid processing, this novel catalyst is expected to gain promising application in the treatment of various dyestuff wastewaters on a large scale.

Microwave Irradiation of Nanohydroxyapatite from Chicken Eggshells and Duck Eggshells

Directory of Open Access Journals (Sweden)

Nor Adzliana Sajahan

2014-01-01

Full Text Available Due to similarity in composition to the mineral component of bones and human hard tissues, hydroxyapatite with chemical formula Ca10(PO46(OH2 has been widely used in medical field. Both chicken and duck eggshells are mainly composed of calcium carbonate. An attempt has been made to fabricate nanohydroxyapatite (nHA by chicken (CES and duck eggshells (DES as calcium carbonate source (CaCO3. CES and DES were reacted with diammonium hydrogen [(NH42HPO4] solution and subjected to microwave heating at 15 mins. Under the effect of microwave irradiation, nHA was produced directly in the solution and involved in crystallographic transformation. Sample characterization was done using by X-ray diffraction (XRD, fourier transform infrared spectroscopy (FTIR, and scanning electron microscopy (SEM.

Low dose irradiation facilitates hepatocellular carcinoma genesis involving HULC.

Science.gov (United States)

Li, Yuan; Ge, Chang; Feng, Guoxing; Xiao, Huiwen; Dong, Jiali; Zhu, Changchun; Jiang, Mian; Cui, Ming; Fan, Saijun

2018-03-24

Irradiation exposure positive correlates with tumor formation, such as breast cancer and lung cancer. However, whether low dose irradiation induces hepatocarcinogenesis and the underlying mechanism remain poorly defined. In the present study, we reported that low dose irradiation facilitated the proliferation of hepatocyte through up-regulating HULC in vitro and in vivo. Low dose irradiation exposure elevated HULC expression level in hepatocyte. Deletion of heightened HULC erased the cells growth accelerated following low dose irradiation exposure. CDKN1, the neighbor gene of HULC, was down-regulated by overexpression of HULC following low dose irradiation exposure via complementary base pairing, resulting in promoting cell cycle process. Thus, our findings provide new insights into the mechanism of low dose irradiation-induced hepatocarcinogenesis through HULC/CDKN1 signaling, and shed light on the potential risk of low dose irradiation for the development of hepatocellular carcinoma in pre-clinical settings. © 2018 Wiley Periodicals, Inc.

Comparison of three optimized digestion methods for rapid determination of chemical oxygen demand: Closed microwaves, open microwaves and ultrasound irradiation

Energy Technology Data Exchange (ETDEWEB)

Domini, Claudia E. [Departamento de Quimica, Universidad Nacional del Sur, Av. Alem 1253, 8000 Bahia Blanca (Argentina); Hidalgo, Montserrat [Departamento de Quimica Analitica, Nutricion y Bromatologia, Universidad de Alicante, Apdo. 99, 03080 Alicante (Spain); Marken, Frank [Department of Chemistry, University of Bath, Bath BA2 7AY (United Kingdom); Canals, Antonio [Departamento de Quimica Analitica, Nutricion y Bromatologia, Universidad de Alicante, Apdo. 99, 03080 Alicante (Spain)]. E-mail: a.canals@ua.es

2006-03-02

In the present work, experimental design was used for the fast optimization of three kinds of sample digestion procedures with the final aim of obtaining the COD value of wastewater samples. The digestion methods evaluated were 'closed microwave-assisted' (CMWD), 'open microwave-assisted' (OMWD) and 'ultrasound-assisted' (USD). Classical digestion was used as reference method. The optimum values for the different variables studied in each method were: 90 psi pressure, 475 W power and 4 min irradiation time (CMWD); 150 deg. C temperature and 4 min irradiation time (OMWD); 90% of maximum nominal power (180 W), 0.9 s (s{sup -1}) cycles and 1 min irradiation time (USD). In all cases, interference concentration that produces a deviation of 10% in COD values is 13.4, 23.4, 21.1 and 2819 mg/L for S{sup 2-}, Fe{sup 2+}, NO{sub 2} {sup -} and Cl{sup -}, respectively. Under optimum conditions, the proposed digestion methods have been successfully applied, with the exception of pyridine, to several pure organic compounds and COD recoveries for 10 real wastewater samples were ranged between 88 and 104% of the values obtained with the classical (open reflux) method used as reference, with R.S.D. lower than 4% in most cases. Thus, the use of ultrasound energy for COD determination seems to be an interesting and promising alternative to conventional open reflux and microwave-assisted digestion methods used for the same purpose since the instrumentation is simpler, cheaper and safer and the digestion step faster than the ones used for the same purpose.

Microwave irradiation induced modifications on the interfaces in SAN/EVA/PVC and PVAc/BPA/PVP ternary polymer blends: Positron lifetime study

International Nuclear Information System (INIS)

Dinesh, Meghala; Chikkakuntappa, Ranganathaiah

2013-01-01

Ternary polymer blends of poly(styrene-co-acrylonitrile)/poly(ethylene-co-vinylacetate)/poly(vinyl chloride) (SAN/EVA/PVC) and poly(vinyl acetate)/bisphenol A/polyvinylpyrrolidone (PVAc/BPA/PVP) with different compositions have been prepared by solvent casting method and characterized by positron lifetime spectroscopy and differential scanning calorimetry DSC. Phase modifications have been induced by irradiating the blends with microwave radiation. These changes have been monitored by measuring the free-volume content in the blends. The results clearly show improved interactions between the constituent polymers of the blends upon microwave irradiation. However, the free-volume data and DSC measurements are found to be inadequate to reveal the changes at the interfaces and the interfaces determine the final properties of the blend. For this we have used hydrodynamic interaction (α ij ) approach developed by us to measure strength of hydrodynamic interaction at the interfaces. These results show that microwave irradiation stabilizes the interfaces if the blend contains strong polar groups. SAN/EVA/PVC blend shows an increased effective hydrodynamic interaction from −3.18 to −4.85 at composition 50/35/15 upon microwave irradiation and PVAc/BPA/PVP blend shows an increased effective hydrodynamic interaction from −3.81 to −7.57 at composition 20/50/30 after irradiation

Microwave irradiation induced modifications on the interfaces in SAN/EVA/PVC and PVAc/BPA/PVP ternary polymer blends: Positron lifetime study

Energy Technology Data Exchange (ETDEWEB)

Dinesh, Meghala; Chikkakuntappa, Ranganathaiah, E-mail: crang1@rediffmail.com

2013-09-01

Ternary polymer blends of poly(styrene-co-acrylonitrile)/poly(ethylene-co-vinylacetate)/poly(vinyl chloride) (SAN/EVA/PVC) and poly(vinyl acetate)/bisphenol A/polyvinylpyrrolidone (PVAc/BPA/PVP) with different compositions have been prepared by solvent casting method and characterized by positron lifetime spectroscopy and differential scanning calorimetry DSC. Phase modifications have been induced by irradiating the blends with microwave radiation. These changes have been monitored by measuring the free-volume content in the blends. The results clearly show improved interactions between the constituent polymers of the blends upon microwave irradiation. However, the free-volume data and DSC measurements are found to be inadequate to reveal the changes at the interfaces and the interfaces determine the final properties of the blend. For this we have used hydrodynamic interaction (α{sub ij}) approach developed by us to measure strength of hydrodynamic interaction at the interfaces. These results show that microwave irradiation stabilizes the interfaces if the blend contains strong polar groups. SAN/EVA/PVC blend shows an increased effective hydrodynamic interaction from −3.18 to −4.85 at composition 50/35/15 upon microwave irradiation and PVAc/BPA/PVP blend shows an increased effective hydrodynamic interaction from −3.81 to −7.57 at composition 20/50/30 after irradiation.

Complex-mediated microwave-assisted synthesis of polyacrylonitrile nanoparticles

Directory of Open Access Journals (Sweden)

Trinath Biswal

2010-10-01

Full Text Available Trinath Biswal, Ramakanta Samal, Prafulla K SahooDepartment of Chemistry, Utkal University, Vani Vihar, Bhubaneswar 751004, IndiaAbstract: The polymerization of acrylonitrile (AN is efficiently, easily, and quickly achieved in the presence of trans-[Co(IIIen2Cl2]Cl complex in a domestic microwave (MW oven. MW irradiation notably promoted the polymerization reaction; this phenomenon is ascribed to the acceleration of the initiator, ammonium persulfate (APS, decomposition by microwave irradiation in the presence of [Co(IIIen2Cl2]Cl. The conversion of monomer to the polymer was mostly excellent in gram scale. Irradiation at low power and time produced more homogeneous polymers with high molecular weight and low polydispersity when compared with the polymer formed by a conventional heating method. The interaction of reacting components was monitored by UV-visible spectrometer. The average molecular weight was derived by gel permeation chromatography (GPC, viscosity methods, and sound velocity by ultrasonic interferometer. The uniform and reduced molecular size was characterized by transmission electron microscopy, the diameter of polyacrylonitrile nanoparticles (PAN being in the range 50–115 nm and 40–230 nm in microwave and conventional heating methods respectively. The surface morphology of PAN prepared by MW irradiation was characterized by scanning electron microscope (SEM. From the kinetic results, the rate of polymerization (Rp was expressed as Rp = [AN]0.63 [APS]0.57 [complex (I].0.88Keywords: microwave, complex catalyst, nanoparticle, kinetics

Gold Nanoparticles and Microwave Irradiation Inhibit Beta-Amyloid Amyloidogenesis

Directory of Open Access Journals (Sweden)

Bastus Neus

2008-01-01

Full Text Available Abstract Peptide-Gold nanoparticles selectively attached to β-amyloid protein (Aβ amyloidogenic aggregates were irradiated with microwave. This treatment produces dramatic effects on the Aβ aggregates, inhibiting both the amyloidogenesis and the restoration of the amyloidogenic potential. This novel approach offers a new strategy to inhibit, locally and remotely, the amyloidogenic process, which could have application in Alzheimer’s disease therapy. We have studied the irradiation effect on the amyloidogenic process in the presence of conjugates peptide-nanoparticle by transmission electronic microscopy observations and by Thioflavine T assays to quantify the amount of fibrils in suspension. The amyloidogenic aggregates rather than the amyloid fibrils seem to be better targets for the treatment of the disease. Our results could contribute to the development of a new therapeutic strategy to inhibit the amyloidogenic process in Alzheimer’s disease.

Lifespan studies on different strains of mice exposed chronically to low levels of whole body gamma irradiation

International Nuclear Information System (INIS)

Fox, L.A.; Klein, A.K.; Cain, G.R.; Rosenblatt, L.S.

1982-01-01

Several strains of mice, chosen for their predisposition to immunohematological disorders, were exposed to low levels of 60 irradiation continuously for four weeks. All individuals were subsequently followed throughout their lifetimes. W/W/sup v/ mice, which are tyically subject to a stem cell deficiency, had a lower cumulative survival rate for the irradiated group than for the unirradiated controls. Irradiated RF/sub j/ mice had a dramatically lower cumulative survival rate than their unirradiated controls. Conversely, BXSB mice, which have a lumphoproliferative autoimmune disorder, had a higher cumulative survival rate after chronic irradiation than did unirradiated BXSBs. Irradiation had no effect upon the survival rate curves of the NZB strain, the murine model for Lupus Erythematosus

Serum-thyroxine levels in microwave-exposed rats

International Nuclear Information System (INIS)

Lu, S.T.; Lebda, N.; Michaelson, S.M.; Pettit, S.

1985-01-01

The nature of the response of the thyroid gland in animals exposed to microwave irradiation is controversial. Animal experimentation has contributed to the controversy because both increased and decreased thyroid functions have been reported. The thyroxine concentration in rats as representative of thyroid function in animals exposed to 2.45-GHz, 120-Hz amplitude-modulated microwaves has been studied. These studies covered a long time span; rats from two commercial sources (BS and CR) were used and subjected to different numbers of exposures, and therefore these data were evaluated for their stability. Two factors could influence in the result significantly, i.e., source of animal and number of sham exposures. Rats used in the 2-hr exposures were from two different commercial sources; rats from CR had a higher (but normal) thyroxine concentration than did rats from BS. Therefore the data of these animals were separated by commercial source for reevaluation. Instead of increased thyroxine concentration in rats exposed at 25, 30, and 40 mW/cm 2 , changes were not noted in any microwave-exposed rats. The influence of sham exposure revealed that appropriate concurrent control and specification of animal source are needed in longitudinal studies. Furthermore, statistical procedures used can greatly influence the conclusions. Thus the specificity of changes in thyroxine concentration in rats exposed to microwaves because of its sporadic occurrence and because of inconsistencies among experiments was doubted

Microwave discharge electrodeless lamps (MDEL). Part IV. Novel self-ignition system incorporating metallic microwave condensing cones to activate MDELs in photochemical reactions.

Science.gov (United States)

Horikoshi, Satoshi; Tsuchida, Akihiro; Sakai, Hideki; Abe, Masahiko; Sato, Susumu; Serpone, Nick

2009-11-01

A metallic condensing cone that concentrates microwave radiation (equivalent to an optical lens) has been developed and used as part of a system to activate a microwave discharge electrodeless lamp (MDEL) in the oxidative treatment of wastewaters by aiding the novel self-ignition of the lamp on irradiation at low microwave power levels. This approach to self-ignition can potentially lead to considerable energy savings in such treatments. System performance was examined for the ignition power of microwaves of such MDEL devices in water, whose usefulness was assessed by investigating the photolytic transformation of aqueous solutions of representatives of three classes of contaminants: chlorinated phenols, herbicides and endocrine disruptors, specifically 4-chlorophenol (4-CP), 2,4-dichlorophenoxyacetic acid (2,4-D) and 4,4'-isopropylidenediphenol (bisphenol-A; BPA), respectively, taken as model wastewaters in air-equilibrated, in oxygen-saturated and in TiO2-containing aqueous media. The results are discussed in terms of the dynamics of the photo-induced degradation processes.

The apoptotic effect and the plausible mechanism of microwave radiation on rat myocardial cells.

Science.gov (United States)

Zhu, Wenhe; Cui, Yan; Feng, Xianmin; Li, Yan; Zhang, Wei; Xu, Junjie; Wang, Huiyan; Lv, Shijie

2016-08-01

Microwaves may exert adverse biological effects on the cardiovascular system at the integrated system and cellular levels. However, the mechanism underlying such effects remains poorly understood. Here, we report a previously uncharacterized mechanism through which microwaves damage myocardial cells. Rats were treated with 2450 MHz microwave radiation at 50, 100, 150, or 200 mW/cm(2) for 6 min. Microwave treatment significantly enhanced the levels of various enzymes in serum. In addition, it increased the malondialdehyde content while decreasing the levels of antioxidative stress enzymes, activities of enzyme complexes I-IV, and ATP in myocardial tissues. Notably, irradiated myocardial cells exhibited structural damage and underwent apoptosis. Furthermore, Western blot analysis revealed significant changes in expression levels of proteins involved in oxidative stress regulation and apoptotic signaling pathways, indicating that microwave irradiation could induce myocardial cell apoptosis by interfering with oxidative stress and cardiac energy metabolism. Our findings provide useful insights into the mechanism of microwave-induced damage to the cardiovascular system.

Microwave-irradiation polyol synthesis of PVP-protected Pt–Ni electrocatalysts for methanol oxidation reaction

CSIR Research Space (South Africa)

Mathe, Ntombizodwa R

2017-01-01

Full Text Available ://doi.org/10.1007/s12678-017-0441-3 Microwave-Irradiation Polyol Synthesis of PVP-Protected Pt–Ni Electrocatalysts for Methanol Oxidation Reaction Ntombizodwa R. Mathe Manfred R. Scriba Rirhandzu S. Rikhotso Neil J. Coville ABSTRACT: Bimetallic Pt...

Improved foilless Ku-band transit-time oscillator for generating gigawatt level microwave with low guiding magnetic field

Energy Technology Data Exchange (ETDEWEB)

Ling, Junpu; He, Juntao, E-mail: hejuntao12@163.com; Zhang, Jiande; Jiang, Tao; Hu, Yi [College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073 (China)

2014-09-15

An improved foilless Ku-band transit-time oscillator with low guiding magnetic field is proposed and investigated in this paper. With a non-uniform buncher and a coaxial TM{sub 02} mode dual-resonant reflector, this improved device can output gigawatt level Ku-band microwave with relatively compact radial dimensions. Besides the above virtue, this novel reflector also has the merits of high TEM reflectance, being more suitable for pre-modulating the electron beam and enhancing the conversion efficiency. Moreover, in order to further increase the conversion efficiency and lower the power saturation time, a depth-tunable coaxial collector and a resonant cavity located before the extractor are employed in our device. Main structure parameters of the device are optimized by particle in cell simulations. The typical simulation result is that, with a 380 kV, 8.2 kA beam guided by a magnetic field of about 0.6 T, 1.15 GW microwave pulse at 14.25 GHz is generated, yielding a conversion efficiency of about 37%.

Synthesis of γ-Nitro Aliphatic Methyl Esters Via Michael Additions Promoted by Microwave Irradiation

OpenAIRE

Escalante, Jaime; Díaz-Coutiño, Francisco D.

2009-01-01

A simple and efficient protocol has been developed for the direct synthesis of γ-nitrobutyric acid methyl esters under microwave irradiation. This methodology reduces reaction times from days to minutes, compared to conventional conditions. Additionally, these conditions increased yields and provided cleaner reactions.

Mitochondria morphologic changes and metabolic effects of rat hippocampus after microwave irradiation

International Nuclear Information System (INIS)

Zhao Li; Peng Ruiyun; Gao Yabing; Wang Shuiming; Wang Lifeng; Dong Qi; Xu Xinping; Ma Junjie

2007-01-01

Objective: To investigate the effect of microwave on mitochondria morphologic and metabolism of rat hippocampus. Methods: 30 male rats were exposed to microwave with the average power density of 30 mW/cm 2 . Rats were sacrificed at 6 h, 1 d, 3 d and 7 d after irradiation. Electron microscope, enzymatic activity staining and spectrophotometer were used to study ultrastructure change of hippocampus mitochondria and activity of ATPase, SDH and MAO. Mitochondrial ATP, ADP and AMP contents were measured by high performance liquid chromatography (HPLC). Results: At 6 h after microwave radiation, the sizes and shapes of hippocampus mitochondria were abnormal and the injury of mitochondria was aggravated at 1 and 3 d after radiation. The mitochondria presented swell, cavitation including disorder, shortness and decrease of crest. The activity of SDH and content of ATP were decreased at 6 h, most serious at 3 d(P<0.01), and recovered at 7 d after radiation. The activity of ATPase and MAO increased notably at 1 d and 3 d after radiation (P<0.01). Conclusions: Microwave can damage the structure and function of mitochondria in rat hippocampus, and cause the energy metabolism of enzyme disorder. (authors)

Glucose administration attenuates spatial memory deficits induced by chronic low-power-density microwave exposure.

Science.gov (United States)

Lu, Yonghui; Xu, Shangcheng; He, Mindi; Chen, Chunhai; Zhang, Lei; Liu, Chuan; Chu, Fang; Yu, Zhengping; Zhou, Zhou; Zhong, Min

2012-07-16

Extensive evidence indicates that glucose administration attenuates memory deficits in rodents and humans, and cognitive impairment has been associated with reduced glucose metabolism and uptake in certain brain regions including the hippocampus. In the present study, we investigated whether glucose treatment attenuated memory deficits caused by chronic low-power-density microwave (MW) exposure, and the effect of MW exposure on hippocampal glucose uptake. We exposed Wistar rats to 2.45 GHz pulsed MW irradiation at a power density of 1 mW/cm(2) for 3 h/day, for up to 30 days. MW exposure induced spatial learning and memory impairments in rats. Hippocampal glucose uptake was also reduced by MW exposure in the absence or presence of insulin, but the levels of blood glucose and insulin were not affected. However, these spatial memory deficits were reversed by systemic glucose treatment. Our results indicate that glucose administration attenuates the spatial memory deficits induced by chronic low-power-density MW exposure, and reduced hippocampal glucose uptake may be associated with cognitive impairment caused by MW exposure. Copyright © 2012 Elsevier Inc. All rights reserved.

Evaluation of the use of inorganic pigments and fillers in cure of epoxy resins by microwave irradiation

International Nuclear Information System (INIS)

Kersting, Daniel; Wiebeck, Helio

2013-01-01

The use of microwave in chemical processes began soon after the WW II. The mechanism of curing via microwave heating is independent of the thermal conductivity of the irradiated material and offers a good solution to operate with materials that do not have a good thermal conductivity, such as polymers. Despite these advantages, the use of multimode microwave ovens, the main source used today, indicates some challenges to overcome. Associated with the use of epoxy resins in various applications, the use of pigments and inorganic fillers has added more variables to be studied. Much of the inorganic fillers used commercially are good absorbers of microwave providing changes in the amount of radiation absorbed, and thus the amount of heat transferred to the epoxy resin curing process. After selecting the key fillers and pigments traditionally used in the production of parts with epoxy resins they were subjected to the same microwave irradiation for evaluation of their behavior alone. In order to observe the effect of mixtures 1, 2, and 5% by weight of filler were added to epoxy resin, and it was verified these effects in the curing process. The preliminary results are promising, because for the same cure cycle for different types of fillers added separately, gains in curing time were obtained, making the process of cure via microwave quick and efficient without substantial losses in thermal properties of the final products obtained. (author)

Effect of microwave irradiation on alfalfa seeds germination and nitrogenase activity of endophytic diazotrophs in seeds

International Nuclear Information System (INIS)

Zhang Shuqing; Li Jianfeng; Shi Shangli; Huo Pinghui; Zhu Xinqiang; Zhao Wenhan; Tao Rong

2011-01-01

Various microwave powers were used to irradiate alfalfa seeds with various time to study the effect of microwave irradiation on nitrogenase activity of endogenous azotobacter and germination of seeds. Germination rate, germination speed and nitrogenase activity of pure cultures that derived from seed-carried azotobacter were tested. The results indicate that : 800 W, 20 s and 500 W, 40 s are found with highest germination rate on the 1 st day, which is 122% and 88.9% times higher than the control group (P th day is 29.8% and 41.9% times longer than the control group, and more sensitive nitrogenase activity is found on condition of various time than various powers. Short time treatments on condition of the two irradiation powers can increase nitrogenase activity conspicuously, and the treatments that treated more than 32 s make nitrogenase activity lower than the control group, conspicuously. Nitrogenase activity is found 104.9% times higher than the control group on condition of 24 s. (authors)

Preparation of sub 3 nm copper nanoparticles by microwave irradiation in the presence of triethylene tetramin

Science.gov (United States)

Tseng, Po-Hao; Wang, Yen-Zen; Hsieh, Tar-Hwa; Ho, Ko-Shan; Tsai, Cheng-Hsien; Chen, Kuan-Ting

2018-02-01

The preparation of sub 3 nm copper nanoparticles (CuNPs) in ethylene glycol (EG) using triethylene tetramine (TETA) as chelating and reducing agents via a rapid microwave (MW) irradiation is reported. The sub 3 nm CuNPs after MW irradiation are clearly seen from the electronic micrographs. The firm chelation of Cu2+ by TETA is illustrated by the dark blue color of Cu2+/TETA/EG solution and the redox reaction is confirmed by the appearance of red color of the mixtures. The optimal mole ratio of TETA/Cu 2+ is found to be 2.5/1 for preparing sub 3 nm CuNPs under the MW irradiation, operated at 800 W for 1 min. The plasmonic absorption λ max demonstrated in UV-vis spectra are found to close to 200 nm for sub 3 nm CuNPs, comparing to 500 ˜ 600 nm for regular, larger CuNPs. The extremely low Tm around 30 °C and the fusion/recrystallization sequence of sub 3 nm CuNPs can be directly measured by their differential scanning calorimetry thermograms.

Effects of increased low-level diode laser irradiation time on extraction socket healing in rats.

Science.gov (United States)

Park, Joon Bong; Ahn, Su-Jin; Kang, Yoon-Goo; Kim, Eun-Cheol; Heo, Jung Sun; Kang, Kyung Lhi

2015-02-01

In our previous studies, we confirmed that low-level laser therapy (LLLT) with a 980-nm gallium-aluminum-arsenide diode laser was beneficial for the healing of the alveolar bone in rats with systemic disease. However, many factors can affect the biostimulatory effects of LLLT. Thus, we attempted to investigate the effects of irradiation time on the healing of extraction sockets by evaluating the expressions of genes and proteins related to bone healing. The left and right first maxillary molars of 24 rats were extracted. Rats were randomly divided into four groups in which extraction sockets were irradiated for 0, 1, 2, or 5 min each day for 3 or 7 days. Specimens containing the sockets were examined using quantitative real-time reverse transcription polymerase chain reaction and western blotting. LLLT increased the expressions of all tested genes, Runx2, collagen type 1, osteocalcin, platelet-derived growth factor-B, and vascular endothelial growth factor, in a time-dependent manner. The highest levels of gene expressions were in the 5-min group after 7 days. Five minutes of irradiation caused prominent increases of the expression of all tested proteins after both 3 and 7 days. The expression level of each protein in group 4 was higher by almost twofold compared with group 1 after 7 days. Laser irradiation for 5 min caused the highest expressions of genes and proteins related to bone healing. In conclusion, LLLT had positive effects on the early stages of bone healing of extraction sockets in rats, which were irradiation time-dependent.

Microwave oven irradiation as a method for bacterial decontamination in a clinical microbiology laboratory

International Nuclear Information System (INIS)

Latimer, J.M.; Matsen, J.M.

1977-01-01

Exposure of 10 frequently isolated clinical pathogens to microwave irradiation resulted in total sterilization with 60 s. Time exposure experiments done with commercially prepared test strips containing Bacillus stearothermophilus spores indicated that 5-min exposure was adequate to ensure sterility of small, contaminated loads

Green synthesis of noble nanometals (Au, Pt, Pd) using glycerol under microwave irradiation conditions

Science.gov (United States)

A newer application of glycerol in the field of nanomaterials synthesis has been developed from both the economic and environmental points of view. Glycerol can act as a reducing agent for the fabrication of noble nanometals, such as Au, Pt, and Pd, under microwave irradiation. T...

Synthesis of γ-Nitro Aliphatic Methyl Esters Via Michael Additions Promoted by Microwave Irradiation

Directory of Open Access Journals (Sweden)

Francisco D. Díaz-Coutiño

2009-04-01

Full Text Available A simple and efficient protocol has been developed for the direct synthesis of γ-nitrobutyric acid methyl esters under microwave irradiation. This methodology reduces reaction times from days to minutes, compared to conventional conditions. Additionally, these conditions increased yields and provided cleaner reactions.

Optimization of microwave-assisted extraction of polysaccharide from Psidium guajava L. fruits.

Science.gov (United States)

Amutha Gnana Arasi, Michael Antony Samy; Gopal Rao, Manchineela; Bagyalakshmi, Janardanan

2016-10-01

This study deals with the optimization of microwave assisted extraction of polysaccharide from Psidium guajava L. fruit using Response surface methodology. To evaluate the effect of three independent variables, Water to plant material ratio, microwave power used for extraction and Irradiation time, central composite design has been employed. The yield is considered as dependent variable. The design model estimated the optimum yield of 6.81677% at 200W microwave power level, 3:1 water to plant material ratio and 20min of irradiation time. Three factors three levels Central composite design coupled with RSM was used to model the extraction process. ANOVA was performed to find the significance of the model. The polysaccharide extracted using microwave assisted extraction process was analyzed using FTIR Spectroscopy. Copyright © 2016 Elsevier B.V. All rights reserved.

The pupal body temperature and inner space temperature of cocoon under microwave irradiation

International Nuclear Information System (INIS)

Kagawa, T.

1996-01-01

The temperature of pupal surface,body and inner space of cocoon on cocoon drying of microwave irradiation was investigated to make clear the effect of temperature with pupa and cocoon shell. After pupal surface temperature and body temperature were risen rapidly in early irradiation and slowly thereafter, these were done fast again. Then these rising degrees fell. The variation of inner space temperature consists three terms: as the first stage of rapidly rising on early irradiation, the second stage of slowly doing and the third stage of fast doing again in temperature. In the first stage and the second stage, the higher the temperature of sending air during irradiation was, the shorter the term was and the higher the reached temperature was. The surface, pupal body and inner space have reached higher temperature than the sending air before cocoon drying was over

Enhanced decomposition of dimethyl phthalate via molecular oxygen activated by Fe-Fe{sub 2}O{sub 3}/AC under microwave irradiation

Energy Technology Data Exchange (ETDEWEB)

Chen, Yiling [Key Laboratory of Pesticide and Chemical Biology of Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079 (China); Ai, Zhihui, E-mail: jennifer.ai@mail.ccnu.edu.cn [Key Laboratory of Pesticide and Chemical Biology of Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079 (China); Zhang, Lizhi [Key Laboratory of Pesticide and Chemical Biology of Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079 (China)

2012-10-15

Highlights: Black-Right-Pointing-Pointer Microwave irradiation induces the electrons transferring from AC to Fe-Fe{sub 2}O{sub 3} and reacts with molecular oxygen. Black-Right-Pointing-Pointer Microwave heating accelerates the electron transferring from AC to Fe-Fe{sub 2}O{sub 3} to generate reactive oxygen species. Black-Right-Pointing-Pointer This environmental remediation method is feasible for aqueous organic pollutants treatment. - Abstract: In this study, we demonstrate that the decomposition of dimethyl phthalate under microwave irradiation could be greatly enhanced over Fe-Fe{sub 2}O{sub 3} nanowires supported on activated carbon (Fe-Fe{sub 2}O{sub 3}/AC). The great enhanced decomposition of dimethyl phthalate could be attributed to a unique microwave induced molecular oxygen activation process. Upon microwave irradiation, electrons could be transferred from activated carbon to zero-valent iron, and then react with molecular oxygen to form O{sub 2}{center_dot}{sup -} and {center_dot}OH radicals for the decomposition of dimethyl phthalate. The deactivation and the regeneration of Fe-Fe{sub 2}O{sub 3}/AC catalyst were systematically studied. We also found that microwave heating could accelerate the electron transferring from AC to Fe-Fe{sub 2}O{sub 3} to generate more reactive oxygen species for the decomposition of DMP than conventional oil bath heating. This novel molecular oxygen activation approach may find applications for wastewater treatment and drinking water purification.

Delivering Microwave Spectroscopy to the Masses: a Design of a Low-Cost Microwave Spectrometer Operating in the 18-26 GHZ Frequency Range

Science.gov (United States)

Steber, Amanda; Pate, Brooks

2014-06-01

Advances in chip-level microwave technology in the communications field have led to the possibilities of low cost alternatives for current Fourier transform microwave (FTMW) spectrometers. Many of the large, expensive microwave components in a traditional design can now be replaced by robust, mass market monolithic microwave integrated circuits (MMICs). "Spectrometer on a board" designs are now feasible that offer dramatic cost reduction for microwave spectroscopy. These chip-level components can be paired with miniature computers to produce compact instruments that are operable through USB. A FTMW spectrometer design using the key MMIC components that drive cost reduction will be presented. Two dual channel synthesizers (Valon Technology Model 5008), a digital pattern generator (Byte Paradigm Wav Gen Xpress), and a high-speed digitizer/arbitrary waveform generator combination unit (Tie Pie HS-5 530 XM) form the key components of the spectrometer for operation in the 18-26.5 GHz range. The design performance is illustrated using a spectrometer that is being incorporated into a museum display for astrochemistry. For this instrument a user interface, developed in Python, has been developed and will be shown.

Experimental study of microwave-induced thermoacoustic imaging

Science.gov (United States)

Jacobs, Ryan T.

Microwave-Induced Thermoacoustic Imaging (TAI) is a noninvasive hybrid modality which improves contrast by using thermoelastic wave generation induced by microwave absorption. Ultrasonography is widely used in medical practice as a low-cost alternative and supplement to magnetic resonance imaging (MRI). Although ultrasonography has relatively high image resolution (depending on the ultrasonic wavelength at diagnostic frequencies), it suffers from low image contrast of soft tissues. In this work samples are irradiated with sub-microsecond electromagnetic pulses inducing acoustic waves in the sample that are then detected with an unfocused transducer. The advantage of this hybrid modality is the ability to take advantage of the microwave absorption coefficients which provide high contrast in tissue samples. This in combination with the superior spatial resolution of ultrasound waves is important to providing a low-cost alternative to MRI and early breast cancer detection methods. This work describes the implementation of a thermoacoustic experiment using a 5 kW peak power microwave source.

A low cost microwave synthesis method for preparation of gold nanoparticles

International Nuclear Information System (INIS)

Ngo Vo Ke Thanh; Lam Quang Vinh; Nguyen Dang Giang; Huynh Thanh Dat

2014-01-01

The gold nanoparticles (GNPs) in 15-20 nm size range have attention for fabrication of smart sensing devices in biomedical sciences as diagnostic tools. Citrate capped GNPs are negatively charged, which can be exploited for electrostatic interactions with some positively charged biomolecules like antibody. In this study, we are developing a low-cost technique by using a common microwave system with medium power for synthesizing gold nanoparticles with using sodium citrate (Na 3 Ct) reduction in chloroauric acid (HAuCl 4 .3H 2 O). It was found that the comparing with normal thermal method, the reaction by the microwave irradiation was much faster. Besides, the effects the sodium citrate concentration and optical properties of gold nanoparticles were studied. The optical properties of gold nanoparticles suspension were characterized by using transmission electron microscopy (TEM), X-ray diffraction (XRD), and UV-Vis absorption spectroscopy (UV-Vis). Maximum absorbance wavelengths (λ max ) for gold nanoparticles are ∼ 518-524 nm with the size of 12-25 nm. The size of gold nanoparticles decreases with increasing concentration of sodium citrate. Besides, the morphology of gold nanoparticles have a spherical shape with face-centered-cubic (fcc) crystalline structure. (author)

Synthesis and characterization of some metal oxide nanocrystals by microwave irradiation

Energy Technology Data Exchange (ETDEWEB)

Rashad, M.; Gaber, A.; Abdelrahim, M. A.; Abdel-Baset, A. M. [Physics Department, Faculty of Science, Assiut University, 71516 Assiut (Egypt); Moharram, A. H. [Physics Dept., College of Science and Arts, King Abdulaziz Univ., Rabigh 21911 (Saudi Arabia)

2013-12-16

Copper oxide and cobalt oxide (CuO, Co3O4) nanocrystals (NCs) have been successfully prepared in a short time using microwave irradiation. The resulted powders of nanocrystals (NCs) were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Thermogravimetric analysis (TGA) measurements are also studied. Fourier-transform infrared (FT-IR) and UV–visible absorption spectroscopy of both kind of nanoparticels are illustrated. Optical absorption analysis indicated the direct band gap for both kinds of nanocrystals.

Atom transfer radical polymerization of styrene under pulsed microwave irradiation

International Nuclear Information System (INIS)

Cheng Zhenping; Zhu Xiulin; Zhou Nianchen; Zhu Jian; Zhang Zhengbiao

2005-01-01

A homogeneous solution atom transfer radical polymerization (ATRP) and reverse atom transfer radical polymerization (RATRP) of styrene (St) in N,N-dimethylformamide (DMF) were successfully carried out under pulsed microwave irradiation (PMI), using 1-bromo-1-phenylethane (1-PEBr)/CuCl/N,N,N',N'',N''-pentamethyldiethylenetriamine (PMDETA) as an initiating system at 85 deg. C and 2,2'-azo-bis-isobutyrontrile (AIBN)/CuCl 2 /PMDETA as an initiating system at 95 deg. C, respectively. The polymerization rates under PMI were greatly increased in comparison with those under identical conventional heating (CH)

Hydrogen Transfer from Hantzsch 1,4-Dihydropyridines to Carbon-Carbon Double Bonds under Microwave Irradiation

OpenAIRE

Jean Jacques Vanden Eynde; Didier Barbry; Guy Cordonnier; Séverine Torchy

2002-01-01

1,4-Dihydropyridines (DHPs) have been used in the reduction of carbon-carbon double bonds under microwave irradiation without solvent. The efficiency of the reactions is dramatically dependent on the steric effects in the DHPs and on the electronic effects in the olefins.

Effect of microwave-enhanced superconductivity in YBa2Cu3O7 bi-crystalline grain boundary weak-links

International Nuclear Information System (INIS)

Fu, C.M.; Chen, C.M.; Lin, H.C.

1994-01-01

We have studied systematically the effect of microwave irradiation on the temperature dependent resistivity R(T) and the current-voltage (I-V) characteristics of YBa 2 Cu 3 O 7-x (YBCO) bicrystalline grain boundary weak-links (GBWLs), with grain boundary of three different tilt angles. The superconducting transition temperature, T c , has significant enhancement upon microwave irradiation. The microwave enhanced T c is increased as a function of incidence microwave power, but limited to an optimum power level. The GBWLs of 45 degrees tilt boundary has shown to be most sensitive to the microwave irradiation power, and the GBWLs of 36.8 degrees tilt boundary has displayed a moderate response. In contrast, no enhancement of T c was observed in the GBWLs of 24 degrees tilt boundary, as well as in the uniform films. Under the microwave irradiation, the R(T) dependence is hysteretic as the transition taken from superconducting state to normal state and vice versa. Mechanisms associated with the redistribution of nonequilibrium quasiparticles under microwave irradiation are discussed

Evaluation the microwave heating of spinel crystals in high-level waste glass

Energy Technology Data Exchange (ETDEWEB)

Christian, J. H. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River Ecology Lab. (SREL); Washington, A. L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River Ecology Lab. (SREL)

2015-08-18

In this report, the microwave heating of a crystal-free and a partially (24 wt%) trevorite-crystallized waste glass simulant were evaluated. The results show that a 500 mg piece of partially crystallized waste glass can be heated from room-temperature to above 1600 °C (as measured by infrared radiometry) within 2 minutes using a single mode, highly focused, 2.45 GHz microwave, operating at 300 W. X-ray diffraction measurements show that the partially crystallized glass experiences an 87 % reduction in trevorite following irradiation and thermal quenching. When a crystal-free analogue of the same waste glass simulant composition is exposed to the same microwave radiation it could not be heated above 450 °C regardless of the heating time.

Effects of the components in rice flour on thermal radical generation under microwave irradiation.

Science.gov (United States)

Lin, Lufen; Huang, Luelue; Fan, Daming; Hu, Bo; Gao, Yishu; Lian, Huizhang; Zhao, Jianxin; Zhang, Hao; Chen, Wei

2016-12-01

The relationships between radical generation under microwave irradiation and the components of various types of rice flour were investigated. Electron paramagnetic resonance (EPR) spectroscopy was used to characterize the radicals found in rice flour samples. The EPR spectra revealed that several types of radical (carbon-centered, tyrosyl and semiquinone) were localized in the starch and protein fractions of the rice flour. The signal intensity of the free radicals was observed to increase exponentially with increasing microwave power and residence time. The rice bran samples exhibited the greatest free radical signal intensity, followed by the brown rice samples and the white rice samples. This finding was consistent for both the native and the microwaved samples. The ratio of rice starch to rice protein also played an important role in the generation of radicals. Copyright © 2016 Elsevier B.V. All rights reserved.

Microwave-enhanced folding and denaturation of globular proteins

DEFF Research Database (Denmark)

Bohr, Henrik; Bohr, Jakob

2000-01-01

It is shown that microwave irradiation can affect the kinetics of the folding process of some globular proteins, especially beta-lactoglobulin. At low temperature the folding from the cold denatured phase of the protein is enhanced, while at a higher temperature the denaturation of the protein from...... its folded state is enhanced. In the latter case, a negative temperature gradient is needed for the denaturation process, suggesting that the effects of the microwaves are nonthermal. This supports the notion that coherent topological excitations can exist in proteins. The application of microwaves...

Reactive oxygen species levels and DNA fragmentation on astrocytes in primary culture after acute exposure to low intensity microwave electromagnetic field.

Science.gov (United States)

Campisi, Agata; Gulino, Marisa; Acquaviva, Rosaria; Bellia, Paolo; Raciti, Giuseppina; Grasso, Rosaria; Musumeci, Francesco; Vanella, Angelo; Triglia, Antonio

2010-03-31

The exposure of primary rat neocortical astroglial cell cultures to acute electromagnetic fields (EMF) in the microwave range was studied. Differentiated astroglial cell cultures at 14 days in vitro were exposed for 5, 10, or 20min to either 900MHz continuous waves or 900MHz waves modulated in amplitude at 50Hz using a sinusoidal waveform and 100% modulation index. The strength of the electric field (rms value) at the sample position was 10V/m. No change in cellular viability evaluated by MTT test and lactate dehydrogenase release was observed. A significant increase in ROS levels and DNA fragmentation was found only after exposure of the astrocytes to modulated EMF for 20min. No evident effects were detected when shorter time intervals or continuous waves were used. The irradiation conditions allowed the exclusion of any possible thermal effect. Our data demonstrate, for the first time, that even acute exposure to low intensity EMF induces ROS production and DNA fragmentation in astrocytes in primary cultures, which also represent the principal target of modulated EMF. Our findings also suggest the hypothesis that the effects could be due to hyperstimulation of the glutamate receptors, which play a crucial role in acute and chronic brain damage. Furthermore, the results show the importance of the amplitude modulation in the interaction between EMF and neocortical astrocytes. Copyright 2010 Elsevier Ireland Ltd. All rights reserved.

Iodine sorption by microwave irradiated hydrotalcites

Energy Technology Data Exchange (ETDEWEB)

Paredes, S.P. [Universidad Autonoma de Puebla, Facultad de Ciencias Quimicas, C.P. 72570, Puebla, Pue (Mexico); Instituto Politecnico Nacional, ESIQIE, C.P. 07738, Mexico, D.F. (Mexico); Fetter, G. [Universidad Autonoma de Puebla, Facultad de Ciencias Quimicas, C.P. 72570, Puebla, Pue (Mexico)]. E-mail: geolarfetter@yahoo.com.mx; Bosch, P. [Universidad Nacional Autonoma de Mexico, Instituto de Investigaciones en Materiales, C.P. 04510, Mexico, D.F. (Mexico); Bulbulian, S. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, C.P. 11801, Mexico, D.F. (Mexico)

2006-12-15

Mg-Al hydrotalcite-like compounds (HT) were prepared by the microwave method on the one hand with ethoxide-acetylacetonate and on the other with acetylacetonate as precursors. They presented a maximum sorption capacity of 2.179 and 1.517 meq of {sup 131}I{sup -}/g of hydrotalcite respectively. When the hydrotalcites were calcined and rehydrated in a {sup 131}I{sup -} solution, iodine sorption decreased in both samples to 1.515 and 1.446, respectively. The corresponding value for nitrated hydrotalcite which was prepared by the conventional method for comparison purposes, was 0.570. The radionuclide content in hydrotalcites was determined by {gamma}-spectrometry. {sup 131}I{sup -} sorption is dependent on two main parameters: one is the type of the interlayer organic material and the second the surface area. It was found that hydrotalcites prepared with ethoxide-acetylacetonate were better sorbents for {sup 131}I{sup -} than those with acetylacetonate. Still, if the specific surface area increased, {sup 131}I{sup -}sorption increased as well; nitrated HT resulted in low specific surface area and a low sorption capacity. It is, therefore, concluded that organic residues present in the samples prepared by the microwave method favor the sorption of radioactive anions, in particular {sup 131}I{sup -} if compared with nitrated and/or carbonate interlayered hydrotalcites.

Pain and mobility improvement and MDA plasma levels in degenerative osteoarthritis, low back pain, and rheumatoid arthritis after infrared A-irradiation

International Nuclear Information System (INIS)

Siems, W.; Siems, R.; Kitzing, M.; Harting, H.; Bresgen, N.; Eckl, P.M.; Brenke, R.

2010-01-01

Infrared (IR)-A irradiation can be useful in back and musculoskeletal pain therapy. In this study joint and vertebral column pain and mobility were measured during two weeks of IR-A irradiation treatment of patients suffering from degenerative osteoarthritis of hip and knee, low back pain, or rheumatoid arthritis. Additionally, before and after IR-A treatment MDA serum levels were measured to check if MDA variations accompany changes in pain intensity and mobility. Two-hundred and seven patients were divided into verum groups getting IR-irradiation, placebo groups getting visible, but not IR irradiation, and groups getting no irradiation. In osteoarthritis significant pain reduction according to Visual Analogue Scale and mobility improvements occurred in the verum group. Even though beneficial mean value changes occurred in the placebo group, the improvements in the placebo and No Irradiation groups were without statistical significance. In low back pain, pain and mobility improvements (by 35 - 40 %) in the verum group were found, too. A delayed (2 nd week) mobility improvement in rheumatoid arthritis was seen. However, pain relief was seen immediately. In patients suffering from low back pain or rheumatoid arthritis, the pain and mobility improvements were accompanied by significant changes of MDA serum levels. However, MDA appears not a sensitive bio factor for changes of the pain intensity in degenerative osteoarthritis. Nevertheless, unaffected or lowered MDA levels during intensive IR-A therapy argue against previous reports on free radical formation upon infrared. In conclusion, rapid beneficial effects of IR-A towards musculoskeletal pain and joint mobility loss were demonstrated. (authors)

Microwave-assisted headspace single-drop microextration of chlorobenzenes from water samples

Energy Technology Data Exchange (ETDEWEB)

Vidal, Lorena [Departamento de Quimica Analitica, Nutricion y Bromatologia, Universidad de Alicante, P.O. Box 99, E-03080 Alicante (Spain); Domini, Claudia E. [Departamento de Quimica Analitica, Nutricion y Bromatologia, Universidad de Alicante, P.O. Box 99, E-03080 Alicante (Spain); Grane, Nuria [Departamento de Quimica Analitica, Nutricion y Bromatologia, Universidad de Alicante, P.O. Box 99, E-03080 Alicante (Spain); Psillakis, Elefteria [Department of Environmental Engineering, Technical University of Crete, Polytechneioupolis, GR-73100 Chania, Crete (Greece); Canals, Antonio [Departamento de Quimica Analitica, Nutricion y Bromatologia, Universidad de Alicante, P.O. Box 99, E-03080 Alicante (Spain)]. E-mail: a.canals@ua.es

2007-05-29

A one-step and in-situ sample preparation method used for quantifying chlorobenzene compounds in water samples has been developed, coupling microwave and headspace single-drop microextraction (MW-HS-SDME). The chlorobenzenes in water samples were extracted directly onto an ionic liquid single-drop in headspace mode under the aid of microwave radiation. For optimization, a Plackett-Burman screening design was initially used, followed by a mixed-level factorial design. The factors considered were: drop volume, aqueous sample volume, stirring speed, ionic strength, extraction time, ionic liquid type, microwave power and length of the Y-shaped glass-tube. The optimum experimental conditions found from this statistical evaluation were: a 5 {mu}L microdrop of 1-hexyl-3-methylimidazolium hexafluorophosphate exposed for 20 min to the headspace of a 30 mL aqueous sample, irradiated by microwaves at 200 W and placed in a 50 mL spherical flask connected to a 25 cm Y-shaped glass-tube. Under the optimised experimental conditions, the response of a high performance liquid chromatographic system was found to be linear over the range studied and with correlation coefficients ranging between 0.9995 and 0.9999. The method showed a good level of repeatability, with relative standard deviations varying between 2.3 and 8.3% (n = 5). Detection limits were found in the low {mu}g L{sup -1} range varying between 0.016 and 0.039 {mu}g L{sup -1}. Overall, the performance of the proposed method demonstrated the favourable effect of microwave sample irradiation upon HS-SDME. Finally, recovery studies from different types of environmental water samples revealed that matrix had little effect upon extraction.

Microwave-assisted headspace single-drop microextration of chlorobenzenes from water samples

International Nuclear Information System (INIS)

Vidal, Lorena; Domini, Claudia E.; Grane, Nuria; Psillakis, Elefteria; Canals, Antonio

2007-01-01

A one-step and in-situ sample preparation method used for quantifying chlorobenzene compounds in water samples has been developed, coupling microwave and headspace single-drop microextraction (MW-HS-SDME). The chlorobenzenes in water samples were extracted directly onto an ionic liquid single-drop in headspace mode under the aid of microwave radiation. For optimization, a Plackett-Burman screening design was initially used, followed by a mixed-level factorial design. The factors considered were: drop volume, aqueous sample volume, stirring speed, ionic strength, extraction time, ionic liquid type, microwave power and length of the Y-shaped glass-tube. The optimum experimental conditions found from this statistical evaluation were: a 5 μL microdrop of 1-hexyl-3-methylimidazolium hexafluorophosphate exposed for 20 min to the headspace of a 30 mL aqueous sample, irradiated by microwaves at 200 W and placed in a 50 mL spherical flask connected to a 25 cm Y-shaped glass-tube. Under the optimised experimental conditions, the response of a high performance liquid chromatographic system was found to be linear over the range studied and with correlation coefficients ranging between 0.9995 and 0.9999. The method showed a good level of repeatability, with relative standard deviations varying between 2.3 and 8.3% (n = 5). Detection limits were found in the low μg L -1 range varying between 0.016 and 0.039 μg L -1 . Overall, the performance of the proposed method demonstrated the favourable effect of microwave sample irradiation upon HS-SDME. Finally, recovery studies from different types of environmental water samples revealed that matrix had little effect upon extraction

Improvement of biomass char-CO{sub 2} gasification reactivity using microwave irradiation and natural catalyst

Energy Technology Data Exchange (ETDEWEB)

Lahijani, Pooya, E-mail: pooya.lahijani@gmail.com [Biomass and Bioenergy Laboratory, School of Mechanical Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang (Malaysia); Mohammadi, Maedeh, E-mail: m.mohammadi@nit.ac.ir [Faculty of Chemical Engineering, Babol Noushirvani University of Technology, 47148 Babol (Iran, Islamic Republic of); Zainal, Zainal Alimuddin, E-mail: mezainal@eng.usm.my [Biomass and Bioenergy Laboratory, School of Mechanical Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang (Malaysia); Mohamed, Abdul Rahman, E-mail: chrahman@usm.my [Low Carbon Economy (LCE) Research Group, School of Chemical Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang (Malaysia)

2015-03-20

Highlights: • We study microwave-induced gasification of EFB ash-loaded biomass char with CO{sub 2}. • Synergistic effect of microwave and catalyst resulted in CO{sub 2} conversion of 93%. • Gasification of pristine char using conventional heating gives CO{sub 2} conversion of 58%. • E{sub a} of 74 and 247 kJ/mol were obtained for microwave and conventional CO{sub 2} gasification. - Abstract: In char-CO{sub 2} gasification, the highly endothermic nature of the Boudouard reaction (CO{sub 2} (g) + C (s) ↔ 2CO (g)) dictates use of very high temperatures to shift the equilibrium towards CO production. In this study, such high temperature (750–900 °C) was provided by microwave irradiation. A microwave heating system was developed to perform the gasification tests by passing CO{sub 2} through a packed bed of oil palm shell (OPS) char. In order to speed up the microwave-induced CO{sub 2} gasification, ash of palm empty fruit bunch (EFB) was used as natural catalyst (rich in potassium) and incorporated into the skeleton of the OPS char. The synergistic effect of microwave and catalyst concluded to very encouraging results, where a CO{sub 2} conversion of 93% was achieved at 900 °C, within 60 min microwave gasification. In comparison, CO{sub 2} conversion in thermal gasification (conventional heating) of pristine OPS char was only 58% under the same operating condition.

Double use of focused microwave irradiation for accelerated matrix hydrolysis and lipid extraction in milk samples

International Nuclear Information System (INIS)

Garcia-Ayuso, L.E.; Luque de Castro, M.D.; Velasco, J.; Dobarganes, M.C.

1999-01-01

Irradiation with microwave energy has allowed to carry out the extraction of lipids from milk samples (namely, cow, goat and sheep) with quantitative results similar to the Weibull–Berntrop extraction procedure but milk fat obtained by microwave assisted extraction undergoes lesser chemical transformation of triglycerides during the whole process. A considerable reduction of the procedure time (50 min versus 10 h) is achieved with similar reproducibility to that provided by the conventional method. An in situ’ solvent recycling step makes the method environmentally clean

Rapid Biosynthesis of Silver Nanoparticles Using Culture Supernatant of Bacteria with Microwave Irradiation

Directory of Open Access Journals (Sweden)

N. Saifuddin

2009-01-01

Full Text Available The development of rapid and reliable processes for the synthesis of nanosized materials is of great importance in the field of nanotechnology. Synthesis of silver nanoparticles using microorganism have been reported, but the process is rather slow. In this paper, we describe a novel combinatorial synthesis approach which is rapid, simple and “green” for the synthesis of metallic nanostructures of noble metals such as silver (Ag, by using a combination of culture supernatanant of Bacillus subtilis and microwave (MW irradiation in water in absence of a surfactant or soft template. It was found that exposure of culture supernatanant of Bacillus subtilis and microwave irradiation to silver ion lead to the formation of silver nanoparticles. The silver nanoparticles were in the range of 5-60 nm in dimension. The nanoparticles were examined using UV-Visible Spectroscopy, and Transmission Electron Microscopy (TEM analyses. The formation of nanoparticles by this method is extremely rapid, requires no toxic chemicals and the nanoparticles are stable for several months. The main conclusion is that the bio-reduction method to produce nanoparticles is a good alternative to the electrochemical methods.

Effect of irradiation and cooking methods on ascorbic acid levels of four potato cultivars

International Nuclear Information System (INIS)

Shirsat, S.G.; Thomas, Paul

1998-01-01

The changes in reduced and total ascorbic acid (AA) contents in control and in tubers irradiated to 100 Gy gamma rays for sprout inhibition were studied by HPLC and iodophenol titrimetry methods in four potato cultivars as a function of storage at 15 degC and after cooking by different methods. Both reduced and total ascorbic acid levels decreased in control tubers during the first 3 months in storage recording respectively 22 to 35% and 26 to 45% losses depending on the cultivar. Irradiated tubers recorded additional losses of 5 to 10% and 6.5 to 13%, respectively in reduced and total ascorbic acid levels during the same period but remained in good marketable conditions. Cooking of tubers in boiling water showed maximum loss in vitamin C content, whereas pressure and microwave cooking recorded least losses. The magnitude of losses in reduced and total vitamin C during cooking was comparable in control and in irradiated tubers. (author)

Environmental levels of microwave radiation around a satellite earth station

International Nuclear Information System (INIS)

Joyner, K.H.; Bangay, M.J.

1986-01-01

This paper discusses the background to claims of possible adverse health effects arising from exposure to environmental levels of microwave radiation around satellite earth stations. Results of a recent survey of the environmental levels of microwave radiation around two 32 metre diameter satellite communications antennas owned and operated by the Overseas Telecommunications Commission (OTC) of Australia are presented. From the measurements obtained in this survey it can be concluded that the environmental levels of microwave radiation around the OTC and similar satellite facilities do not pose a health risk to persons in the vicinity

Effects of accelerated electrons and microwaves on frozen enzyme lactate dehydrogenase

International Nuclear Information System (INIS)

Hategan, A.; Martin, D.; Popescu, L.M.; Butan, C.

2000-01-01

Results on the influence of 6 MeV electron beam irradiation and 2.45 GHz 565 W microwaves as well as the effects of the combined electron and microwave irradiation, at - 21 deg. C, on enzyme lactate dehydrogenase are presented. The microwave irradiated macromolecules exhibited a non-linear behaviour (successive activation and inactivation of the enzyme molecules) suggesting the major influence of the nonthermal component of microwave radiation. The combined electron and microwave irradiation lead to a similar decrease of the activity as the electron beam irradiation, the microwave influence being apparently insignificant in the dose, power and time ranges used. Radiation target analysis of the enzymatic decrease due to electron irradiation indicated very large aggregation of the enzyme molecules. Our data suggest that radiation target analysis is not suitable to measure the molecular mass of lactate dehydrogenase, when irradiating frozen enzyme suspensions. (authors)

Microwave and thermal pretreatment as methods for increasing the biogas potential of secondary sludge from municipal wastewater treatment plants

DEFF Research Database (Denmark)

Kuglarz, Mariusz; Karakashev, Dimitar Borisov; Angelidaki, Irini

2013-01-01

In the present study, the sludge was pretreated with microwave irradiation and low-temperature thermal method, both conducted under the same temperature range (30–100°C). Microwave pretreatment was found to be superior over the thermal treatment with respect to sludge solubilization and biogas pr...... experiments indicated that pre-treated sludge (microwave irradiation: 900W, temperature: 60–70°C) gave 35% more methane, compared to untreated sludge. Moreover, the results of this study clearly demonstrated that microwave pretreated sludge showed better degree of sanitation....

Effect of Microwave Disinfection on Compressive and Tensile Strengths of Dental Stones

Directory of Open Access Journals (Sweden)

Mahmood Robati Anaraki

2013-03-01

Full Text Available Background and aims. Although microwave irradiation has been used for disinfection of dental stone casts, there are concerns regarding mechanical damage to casts during the process. The aim of this study was to evaluate the effect of microwave irradiation on the compressive strength (CS and diametral tensile strength (DTS of stone casts. Materials and methods. In this in vitro study, 80 cylindrical type III and IV stone models (20 × 40 mm were prepared and divided into 8 groups of 10. The DTS and CS of the specimens were measured by a mechanical testing machine at a crosshead speed of 0.5 cm/min after 7 times of frequent wetting, irradiating at an energy level of 600 W for 3 minutes and cooling. Data were analyzed by Student’s t-test. Results. Microwave irradiation significantly increased DTS of type III and IV to 5.23 ± 0.64 and 8.17 ± 0.94, respectively (P < 0.01. Conclusion. According to the results, microwave disinfection increases DTS of type III and IV stone casts without any effects on their CS.

Electron-beam and microwave treatment of some microbial strains

International Nuclear Information System (INIS)

Martin, D.; Ferdes, O.S.; Minea, R.; Tirlea, A.; Badea, M.; Plamadeala, S.; Ferdes, M.

1998-01-01

The experimental results concerning the combined effects of microwaves and accelerated electron beams on various microbial strains such as E. coli, Salmonella sp. and Monascus purpureus are presented. A special designed microwave applicator with a 2.45 GHz frequency CW magnetron of 850 maximum output power and with associate electronics that allow to control the microwave power, the current intensity, and the exposure time was used. The electron-beam irradiation was performed at different irradiation doses and at a dose rate of 1.5 - 2.0 kGy/min by using a linac at a mean electron energy about 6 MeV, mean bean current of 10 μA, pulse period of 3.5 μs and repetition frequency 100 Hz. The experiments were carried out in 5 variants: microwave treatment; electron-beam irradiation; microwaves followed by electron beam; electrons followed by microwaves; and simultaneous application of microwaves and electron beam. The microbiocidal effect was found to be enhanced by additional use of microwave energy to electron beam irradiation. Enhancement of inactivation rate is only remarkable for the microwave treatment or simultaneous electron beam and microwave irradiation at a temperature above the critical value at which microorganisms begin to perish by heat. Simultaneous irradiation with electron beam and microwaves results in a reduction of temperature and time as well as in the decrease of the upper limit of required electron beam absorbed dose for an assumed microbiological quality parameter. The results obtained indicate the occurrence of a synergistic effect of the two physical fields on a non-thermal basis. Hence, combined microwave-electron beam treatment may be applied as an effective method to reduce microbial load

Induction of stress volatiles and changes in essential oil content and composition upon microwave exposure in the aromatic plant Ocimum basilicum

Energy Technology Data Exchange (ETDEWEB)

Lung, Ildikó [National Institute for Research and Development of Isotopic and Molecular Technologies, 67-103 Donat Street, Cluj-Napoca 400293 (Romania); Soran, Maria-Loredana, E-mail: loredana.soran@itim-cj.ro [National Institute for Research and Development of Isotopic and Molecular Technologies, 67-103 Donat Street, Cluj-Napoca 400293 (Romania); Opriş, Ocsana; Truşcă, Mihail Radu Cătălin [National Institute for Research and Development of Isotopic and Molecular Technologies, 67-103 Donat Street, Cluj-Napoca 400293 (Romania); Niinemets, Ülo [Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, 1 Kreutzwaldi Street, Tartu 51014 (Estonia); Copolovici, Lucian [Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, 1 Kreutzwaldi Street, Tartu 51014 (Estonia); Institute of Technical and Natural Sciences Research-Development of “Aurel Vlaicu” University, 2 Elena Drăgoi Street, Arad 310330 (Romania)

2016-11-01

Exposure to sustained low intensity microwaves can constitute a stress for the plants, but its effects on plant secondary chemistry are poorly known. We studied the influence of GSM and WLAN-frequency microwaves on emissions of volatile organic compounds and content of essential oil in the aromatic plant Ocimum basilicum L. hypothesizing that microwave exposure leads to enhanced emissions of stress volatiles and overall greater investment in secondary compounds. Compared to the control plants, microwave irradiation led to decreased emissions of β-pinene, α-phellandrene, bornyl acetate, β-myrcene, α-caryophyllene and benzaldehyde, but increased emissions of eucalyptol, estragole, caryophyllene oxide, and α-bergamotene. The highest increase in emission, 21 times greater compared to control, was observed for caryophyllene oxide. The irradiation resulted in increases in the essential oil content, except for the content of phytol which decreased by 41% in the case of GSM-frequency, and 82% in the case of WLAN-frequency microwave irradiation. The strongest increase in response to WLAN irradiation, > 17 times greater, was observed for hexadecane and octane contents. Comparisons of volatile compositions by multivariate analyses demonstrated a clear separation of different irradiance treatments, and according to the changes in the volatile emissions, the WLAN-frequency irradiation represented a more severe stress than the GSM-frequency irradiation. Overall, these results demonstrating important modifications in the emission rates, essential oil content and composition indicate that microwave irradiation influences the quality of herbage of this economically important spice plant. - Highlights: • Microwave irradiation represents a stress for the plants. • Microwave exposure leads to enhanced emissions of stress volatiles. • O. basilicum irradiation with microwaves increases the essential oil content. • Microwave pollution can constitute a threat to the

Induction of stress volatiles and changes in essential oil content and composition upon microwave exposure in the aromatic plant Ocimum basilicum

International Nuclear Information System (INIS)

Lung, Ildikó; Soran, Maria-Loredana; Opriş, Ocsana; Truşcă, Mihail Radu Cătălin; Niinemets, Ülo; Copolovici, Lucian

2016-01-01

Exposure to sustained low intensity microwaves can constitute a stress for the plants, but its effects on plant secondary chemistry are poorly known. We studied the influence of GSM and WLAN-frequency microwaves on emissions of volatile organic compounds and content of essential oil in the aromatic plant Ocimum basilicum L. hypothesizing that microwave exposure leads to enhanced emissions of stress volatiles and overall greater investment in secondary compounds. Compared to the control plants, microwave irradiation led to decreased emissions of β-pinene, α-phellandrene, bornyl acetate, β-myrcene, α-caryophyllene and benzaldehyde, but increased emissions of eucalyptol, estragole, caryophyllene oxide, and α-bergamotene. The highest increase in emission, 21 times greater compared to control, was observed for caryophyllene oxide. The irradiation resulted in increases in the essential oil content, except for the content of phytol which decreased by 41% in the case of GSM-frequency, and 82% in the case of WLAN-frequency microwave irradiation. The strongest increase in response to WLAN irradiation, > 17 times greater, was observed for hexadecane and octane contents. Comparisons of volatile compositions by multivariate analyses demonstrated a clear separation of different irradiance treatments, and according to the changes in the volatile emissions, the WLAN-frequency irradiation represented a more severe stress than the GSM-frequency irradiation. Overall, these results demonstrating important modifications in the emission rates, essential oil content and composition indicate that microwave irradiation influences the quality of herbage of this economically important spice plant. - Highlights: • Microwave irradiation represents a stress for the plants. • Microwave exposure leads to enhanced emissions of stress volatiles. • O. basilicum irradiation with microwaves increases the essential oil content. • Microwave pollution can constitute a threat to the

Effects of Low-Dose Microwave on Healing of Fractures with Titanium Alloy Internal Fixation: An Experimental Study in a Rabbit Model

Science.gov (United States)

Zhang, Han; Fu, Tengfei; Jiang, Lan; Bai, Yuehong

2013-01-01

Background Microwave is a method for improving fracture repair. However, one of the contraindications for microwave treatment listed in the literature is surgically implanted metal plates in the treatment field. The reason is that the reflection of electromagnetic waves and the eddy current stimulated by microwave would increase the temperature of magnetic implants and cause heat damage in tissues. Comparing with traditional medical stainless steel, titanium alloy is a kind of medical implants with low magnetic permeability and electric conductivity. But the effects of microwave treatment on fracture with titanium alloy internal fixation in vivo were not reported. The aim of this article was to evaluate the security and effects of microwave on healing of a fracture with titanium alloy internal fixation. Methods Titanium alloy internal fixation systems were implanted in New Zealand rabbits with a 3.0 mm bone defect in the middle of femur. We applied a 30-day microwave treatment (2,450MHz, 25W, 10 min per day) to the fracture 3 days after operation. Temperature changes of muscle tissues around implants were measured during the irradiation. Normalized radiographic density of the fracture gap was measured on the 10th day and 30th day of the microwave treatment. All of the animals were killed after 10 and 30 days microwave treatment with histologic and histomorphometric examinations performed on the harvested tissues. Findings The temperatures did not increase significantly in animals with titanium alloy implants. The security of microwave treatment was also supported by histology of muscles, nerve and bone around the implants. Radiographic assessment, histologic and histomorphometric examinations revealed significant improvement in the healing bone. Conclusion Our results suggest that, in the healing of fracture with titanium alloy internal fixation, a low dose of microwave treatment may be a promising method. PMID:24086626

Characterization of low-temperature microwave loss of thin aluminum oxide formed by plasma oxidation

Energy Technology Data Exchange (ETDEWEB)

Deng, Chunqing, E-mail: cdeng@uwaterloo.ca; Otto, M.; Lupascu, A., E-mail: alupascu@uwaterloo.ca [Institute for Quantum Computing, Department of Physics and Astronomy, and Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada)

2014-01-27

We report on the characterization of microwave loss of thin aluminum oxide films at low temperatures using superconducting lumped resonators. The oxide films are fabricated using plasma oxidation of aluminum and have a thickness of 5 nm. We measure the dielectric loss versus microwave power for resonators with frequencies in the GHz range at temperatures from 54 to 303 mK. The power and temperature dependence of the loss are consistent with the tunneling two-level system theory. These results are relevant to understanding decoherence in superconducting quantum devices. The obtained oxide films are thin and robust, making them suitable for capacitors in compact microwave resonators.

Biological effects of low-level laser irradiation on umbilical cord mesenchymal stem cells

International Nuclear Information System (INIS)

Chen, Hongli; Wang, Hong; Li, Yingxin; Liu, Weichao; Chen, Zhuying; Wang, Chao

2016-01-01

Low-level laser irradiation (LLLI) can enhance stem cell (SC) activity by increasing migration and proliferation. This study investigated the effects of LLLI on proliferation, enzymatic activity, and growth factor production in human umbilical cord mesenchymal SCs (hUC-MSCs) as well as the underlying mechanisms. hUC-MSCs were assigned to a control group (non-irradiation group) and three LLLI treatment groups (635 nm group, 808 nm group, and 635/808 nm group). Laser power density and energy density of 20 mW/cm"2 and 12 J/cm"2, respectively, were used for each experiment. The proliferation rate was higher in the 635 nm as compared to the other groups. LLLI at 808 nm did not induce cell proliferation. ROS levels in cells exposed to 635, 808, and 635/808 nm radiation were increased by 52.81%, 26.89%, and 21.15%, respectively, relative to the control group. CAT, tGPx, and SOD activity was increased. LLLI at 808 nm increased the levels of IL-1, IL-6, and NFκB but not VEGF. LLLI improved hUC-MSCs function and increased antioxidant activity. Dual-wavelength LLLI had more potent effects on hUC-MSCs than single-wavelength treatment. LLLI has potential applications in the preconditioning of hUC-MSCs in vitro prior to transplantation, which could improve the regenerative capacity of cells.

Biological effects of low-level laser irradiation on umbilical cord mesenchymal stem cells

Science.gov (United States)

Chen, Hongli; Wang, Hong; Li, Yingxin; Liu, Weichao; Wang, Chao; Chen, Zhuying

2016-04-01

Low-level laser irradiation (LLLI) can enhance stem cell (SC) activity by increasing migration and proliferation. This study investigated the effects of LLLI on proliferation, enzymatic activity, and growth factor production in human umbilical cord mesenchymal SCs (hUC-MSCs) as well as the underlying mechanisms. hUC-MSCs were assigned to a control group (non-irradiation group) and three LLLI treatment groups (635 nm group, 808 nm group, and 635/808 nm group). Laser power density and energy density of 20 mW/cm2 and 12 J/cm2, respectively, were used for each experiment. The proliferation rate was higher in the 635 nm as compared to the other groups. LLLI at 808 nm did not induce cell proliferation. ROS levels in cells exposed to 635, 808, and 635/808 nm radiation were increased by 52.81%, 26.89%, and 21.15%, respectively, relative to the control group. CAT, tGPx, and SOD activity was increased. LLLI at 808 nm increased the levels of IL-1, IL-6, and NFκB but not VEGF. LLLI improved hUC-MSCs function and increased antioxidant activity. Dual-wavelength LLLI had more potent effects on hUC-MSCs than single-wavelength treatment. LLLI has potential applications in the preconditioning of hUC-MSCs in vitro prior to transplantation, which could improve the regenerative capacity of cells.

Biological effects of low-level laser irradiation on umbilical cord mesenchymal stem cells

Energy Technology Data Exchange (ETDEWEB)

Chen, Hongli; Wang, Hong; Li, Yingxin, E-mail: yingxinli2005@126.com; Liu, Weichao; Chen, Zhuying [Key Laboratory of Laser Medicine of Tianjin, Institute of Biomedical Engineering, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300192 (China); Wang, Chao [Biomedical Engineering and Technology College, Tianjin Medical University, Tianjin, 300070 (China)

2016-04-15

Low-level laser irradiation (LLLI) can enhance stem cell (SC) activity by increasing migration and proliferation. This study investigated the effects of LLLI on proliferation, enzymatic activity, and growth factor production in human umbilical cord mesenchymal SCs (hUC-MSCs) as well as the underlying mechanisms. hUC-MSCs were assigned to a control group (non-irradiation group) and three LLLI treatment groups (635 nm group, 808 nm group, and 635/808 nm group). Laser power density and energy density of 20 mW/cm{sup 2} and 12 J/cm{sup 2}, respectively, were used for each experiment. The proliferation rate was higher in the 635 nm as compared to the other groups. LLLI at 808 nm did not induce cell proliferation. ROS levels in cells exposed to 635, 808, and 635/808 nm radiation were increased by 52.81%, 26.89%, and 21.15%, respectively, relative to the control group. CAT, tGPx, and SOD activity was increased. LLLI at 808 nm increased the levels of IL-1, IL-6, and NFκB but not VEGF. LLLI improved hUC-MSCs function and increased antioxidant activity. Dual-wavelength LLLI had more potent effects on hUC-MSCs than single-wavelength treatment. LLLI has potential applications in the preconditioning of hUC-MSCs in vitro prior to transplantation, which could improve the regenerative capacity of cells.

A study on microwave oxidation of landfill leachate—Contributions of microwave-specific effects

International Nuclear Information System (INIS)

Chou, Yu-Chieh; Lo, Shang-Lien; Kuo, Jeff; Yeh, Chih-Jung

2013-01-01

Highlights: ► pH has an insignificant effect on TOC removals and 550 W has a well performance. ► MOP has well removals of color, UV 254 , and TOC at 550 W/85 °C. ► TOC removals were higher at higher microwave setting (550 W vs. 128 W). ► The microwave-specific effects on TOC removal were usually synergistic in MOP. ► COD analyses showed persulfate decayed rapidly in either MOP or CHO treatment. -- Abstract: Microwave oxidation process (MOP) was evaluated for treatment of landfill leachate. The experimental parameters include pH, temperature, oxidant doses, microwave power setting, and irradiation time. The study explored the microwave-specific effects of the MOP. The contributions of pure thermal, persulfate oxidation and microwave irradiation on TOC removal were quantified. It was then found the combinations of them were usually synergistic in MOP except two of them were antagonistic (128 W/85 °C/1 M Na 2 S 2 O 8 and 128 W/85 °C/2 M Na 2 S 2 O 8 ). At the highest temperature tested (85 °C) in this study, microwave irradiation may cause generation and termination of oxidizing radicals at adverse rates. The study also found that persulfate decayed rapidly in either MOP or conventional heating oxidation (CHO) treatment of landfill leachate

Effects of microwave power and irradiation time on pectin extraction from watermelon rinds (Citrullus lanatus) with acetic acid using microwave assisted extraction method

Science.gov (United States)

Sari, A. M.; Ishartani, D.; Dewanty, P. S.

2018-01-01

The aims of this research are to study the effect of microwave power (119.7 W, 199.5 W and 279.3 W) and irradiation time (6, 9 and 12 min) on pectin extraction by using Microwave Assisted Extraction (MAE) with acetic acid and to do a preliminary characterization of pectin from watermelon rinds. A randomized factorial design with two factors was used to determine the effect of microwave power and processing time on the yield, equivalent weight, degree of methoxylation (DM), galacturonic acid content (GA) and the degree of esterification (DE) of extracted pectin. The results showed that extracted pectin from watermelon rinds using MAE method have yield ranged from 3.925% to 5.766%, with equivalent weight ranged from 1249.702 to 2007.756. Extracted pectin have a DM value ranged from 3.89% to 10.81%. Galacturonic acid content that meets with IPPA standard resulted from extraction condition of 279.3-watt microwave power for 9 min and 12 min. The degree of esterification (DE) value ranged from 56.86% to 85.76%, and this value exhibited a relatively high methoxyl pectin (>50%). The best pectin properties was obtained at a microwave power of 279.3 watts for 12 min.

Solid solutions of gadolinium doped zinc oxide nanorods by combined microwave-ultrasonic irradiation assisted crystallization

Science.gov (United States)

Kiani, Armin; Dastafkan, Kamran; Obeydavi, Ali; Rahimi, Mohammad

2017-12-01

Nanocrystalline solid solutions consisting of un-doped and gadolinium doped zinc oxide nanorods were fabricated by a modified sol-gel process utilizing combined ultrasonic-microwave irradiations. Polyvinylpyrrolidone, diethylene glycol, and triethylenetetramine respectively as capping, structure directing, and complexing agents were used under ultrasound dynamic aging and microwave heating to obtain crystalline nanorods. Crystalline phase monitoring, lattice parameters and variation, morphology and shape, elemental analysis, functional groups, reducibility, and the oxidation state of emerged species were examined by PXRD, FESEM, TEM, EDX, FTIR, micro Raman, H2-TPR, and EPR techniques. Results have verified that irradiation mechanism of gelation and crystallization reduces the reaction time, augments the crystal quality, and formation of hexagonal close pack structure of Wurtzite morphology. Besides, dissolution of gadolinium within host lattice involves lattice deformation, unit cell distortion, and angular position variation. Structure related shape and growth along with compositional purity were observed through microscopic and spectroscopic surveys. Furthermore, TPR and EPR studies elucidated more detailed behavior upon exposure to the exerted irradiations and subsequent air-annealing including the formed oxidation states and electron trapping centers, presence of gadolinium, zinc, and oxygen disarrays and defects, as well as alteration in the host unit cell via gadolinium addition.

Low dose irradiation reduces cancer mortality rates

International Nuclear Information System (INIS)

Luckey, T.D.

2000-01-01

Low doses of ionizing radiation stimulate development, growth, memory, sensual acuity, fecundity, and immunity (Luckey, T.D., ''Radiation Hormesis'', CRC Press, 1991). Increased immune competence reduces cancer mortality rates and provides increased average lifespan in animals. Decreased cancer mortality rates in atom bomb victims who received low dose irradiation makes it desirable to examine populations exposed to low dose irradiation. Studies with over 300,000 workers and 7 million person-years provide a valid comparison of radiation exposed and control unclear workers (Luckey, T.D., Nurture with Ionizing Radiation, Nutrition and Cancer, 34:1-11, 1999). Careful selection of controls eliminated any ''healthy worker effect''. The person-year corrected average indicated the cancer mortality rate of exposed workers was only 51% that of control workers. Lung cancer mortality rates showed a highly significant negative correlation with radon concentrations in 272,000 U.S. homes (Cohen, B.L., Health Physics 68:157-174, 1995). In contrast, radon concentrations showed no effect on lung cancer rates in miners from different countries (Lubin, J.H. Am. J. Epidemiology 140:323-332, 1994). This provides evidence that excessive lung cancer in miners is caused by particulates (the major factor) or toxic gases. The relative risk for cancer mortality was 3.7% in 10,000 Taiwanese exposed to low level of radiation from 60 Co in their steel supported homes (Luan, Y.C. et al., Am. Nuclear Soc. Trans. Boston, 1999). This remarkable finding needs further study. A major mechanism for reduced cancer mortality rates is increased immune competence; this includes both cell and humoral components. Low dose irradiation increases circulating lymphocytes. Macrophage and ''natural killer'' cells can destroy altered (cancer) cells before the mass becomes too large. Low dose irradiation also kills suppressor T-cells; this allows helper T-cells to activate killer cells and antibody producing cells

Sensory dynamics of intense microwave irradiation: A comparative study of aversive behaviors by mice and rats

Energy Technology Data Exchange (ETDEWEB)

Justesen, D.R.

1981-10-01

The results of two experiments are reported, the first on 24 mice and 14 rats, all experimentally naive, that were observed for evidence of adventitious escape from faradic shock or from a potentially lethal, 2450-MHz microwave field in a multi-mode cavity. All of ten rats irradiated at a whole-body-averaged dose rate of 60 mW/g convulsed and expired, presumably from radiation-induced hyperpyrexia. Eight of ten mice irradiated at 60 mW/g survived the four sessions of irradiation, but reliable evidence of escape learning was not observed. The data of the second experiment, which was a pilot study of four rats with an extensive history of exposure to intense but intermittently applied microwave fields, revealed that the animals learned to thermoregulate behaviorally by locomoting in and out of the safe-area circle. A strong relation between dose rate (30, 60, and 120 mW/g) and proportion of time spent in the safe area was observed (r = .97). Post-exposure means of colonic temperature during three sets of sessions under the different rates of energy dosing were highly stable and averaged 39.6 deg C.

Effect of microwave-enhanced superconductivity in YBa{sub 2}Cu{sub 3}O{sub 7} bi-crystalline grain boundary weak-links

Energy Technology Data Exchange (ETDEWEB)

Fu, C.M.; Chen, C.M.; Lin, H.C. [National Chiao-Tung Univ., Taiwan (China)] [and others

1994-12-31

We have studied systematically the effect of microwave irradiation on the temperature dependent resistivity R(T) and the current-voltage (I-V) characteristics of YBa{sub 2}Cu{sub 3}O{sub 7-x} (YBCO) bicrystalline grain boundary weak-links (GBWLs), with grain boundary of three different tilt angles. The superconducting transition temperature, T{sub c}, has significant enhancement upon microwave irradiation. The microwave enhanced T{sub c} is increased as a function of incidence microwave power, but limited to an optimum power level. The GBWLs of 45{degrees} tilt boundary has shown to be most sensitive to the microwave irradiation power, and the GBWLs of 36.8{degrees} tilt boundary has displayed a moderate response. In contrast, no enhancement of T{sub c} was observed in the GBWLs of 24{degrees} tilt boundary, as well as in the uniform films. Under the microwave irradiation, the R(T) dependence is hysteretic as the transition taken from superconducting state to normal state and vice versa. Mechanisms associated with the redistribution of nonequilibrium quasiparticles under microwave irradiation are discussed.

In vitro analysis of low-level laser irradiation on human osteoblast-like cells proliferation

Science.gov (United States)

Bloise, Nora; Saino, Enrica; Bragheri, Francesca; Minzioni, Paolo; Cristiani, Ilaria; Imbriani, Marcello; Visai, Livia

2011-07-01

The objective of this study was to examine the in vitro effect of a single or a multiple doses of low-level laser irradiation (LLLI) on proliferation of the human osteosarcoma cell line, SAOS-2. SAOS-2 cells were divided in five groups and exposed to LLLI (659 nm diode laser; 11 mW power output): group I as a control (dark), group II exposed to a single laser dose of 1 J/cm2, group III irradiated with a single dose of 3 J/cm2, and group IV and V exposed for three consecutive days to 1 or 3 J/cm², respectively. Cellular proliferation was assessed daily up to 7 days of culturing. The obtained results showed an increase in proliferative capacity of SAOS-2 cells during the first 96 h of culturing time in once-irradiated cells, as compared to control cells. Furthermore, a significantly higher proliferation in the group IV and V was detected if compared to a single dose or to control group after 96 h and 7 days. In conclusion, the effect of the single dose on cell proliferation was transitory and repeated irradiations were necessary to observe a strong enhancement of SAOS-2 growth. As a future perspective, we would like to determine the potential of LLLI as a new approach for promoting bone regeneration onto biomaterials.

Improvement of multi-level resistive switching characteristics in solution-processed AlO x -based non-volatile resistive memory using microwave irradiation

Science.gov (United States)

Kim, Seung-Tae; Cho, Won-Ju

2018-01-01

We fabricated a resistive random access memory (ReRAM) device on a Ti/AlO x /Pt structure with solution-processed AlO x switching layer using microwave irradiation (MWI), and demonstrated multi-level cell (MLC) operation. To investigate the effect of MWI power on the MLC characteristics, post-deposition annealing was performed at 600-3000 W after AlO x switching layer deposition, and the MLC operation was compared with as-deposited (as-dep) and conventional thermally annealing (CTA) treated devices. All solution-processed AlO x -based ReRAM devices exhibited bipolar resistive switching (BRS) behavior. We found that these devices have four-resistance states (2 bits) of MLC operation according to the modulation of the high-resistance state (HRSs) through reset voltage control. Particularly, compared to the as-dep and CTA ReRAM devices, the MWI-treated ReRAM devices showed a significant increase in the memory window and stable endurance for multi-level operation. Moreover, as the MWI power increased, excellent MLC characteristics were exhibited because the resistance ratio between each resistance state was increased. In addition, it exhibited reliable retention characteristics without deterioration at 25 °C and 85 °C for 10 000 s. Finally, the relationship between the chemical characteristics of the solution-processed AlO x switching layer and BRS-based multi-level operation according to the annealing method and MWI power was investigated using x-ray photoelectron spectroscopy.

Study of viability on the destruction of weed seeds in the soil by microwave radiation

International Nuclear Information System (INIS)

Velazquez-Marti, B.; Osca, J.M.; Jorda, C.; Marzal, A.

2003-01-01

This work has been carried out to study the thermic effects over weed seeds in typical orchard soil irradiated by its surface with microwave. A previous treatment was carried out in a domestic microwave oven, using 660-watt power. With this laboratory oven, we have investigated three kind of weed seeds: Lolium perenne, Sinopsis alba and Setaria sativa. These previous experiments showed a important decrease of germination with short irradiating times. After previous treatment, a microwave applicator, designed to achieve wide distribution of superficial irradiation energy, was evaluated. This applicator is powered by a 4-kilowatt magnetron through a slotted waveguide. With this oven, we have investigated two kind of weed seeds at several depths: Lolium perenne and Brassica napus var. oleifera. For a soil column, temperature increments reduce seeds germination to a maximum of 5 centimetres. Deeper, the increments of temperature are very low for short irradiating times, so it will be negligible for our purpose. This applicator lets approach better to real treatments focused into the development of a continuous microwave oven for disinfecting seedbed and greenhouse crop substratum. (author) [es

Kinetic advantages of using microwaves in the emulsion polymerization of MMA

Energy Technology Data Exchange (ETDEWEB)

Costa, C. [Departamento de Engenharia Quimica, Universidade Federal de Santa Catarina, Campus Universitario, CEP: 88040-900, Florianopolis, SC (Brazil); Santos, A.F.; Fortuny, M. [Programa de Mestrado em Engenharia de Processos, Universidade Tiradentes, Instituto de Tecnologia e Pesquisa, Av. Murilo Dantas, 300, CEP: 49032-490, Aracaju, SE (Brazil); Araujo, P.H.H. [Departamento de Engenharia Quimica, Universidade Federal de Santa Catarina, Campus Universitario, CEP: 88040-900, Florianopolis, SC (Brazil); Sayer, C. [Departamento de Engenharia Quimica, Universidade Federal de Santa Catarina, Campus Universitario, CEP: 88040-900, Florianopolis, SC (Brazil)], E-mail: csayer@enq.ufsc.br

2009-03-01

Microwave irradiation has been an interesting alternative for heating systems and several chemical reactions. In polymerization processes, microwaves can enhance reaction rates or improve specific characteristics of the formed polymer. In this work, the use of microwave irradiation in emulsion polymerization reactions has been studied, using a commercial microwave reactor, which is able to perform syntheses under controlled conditions of temperature and power. Methyl methacrylate emulsion polymerization reactions were faster, resulting in smaller polymer particles, in comparison to the conventional heating method (reactions in a jacketed reactor). Different effects were observed in the emulsion polymerization of butyl acrylate. To study the effect of high power microwave irradiation upon the emulsion polymerization, a pulsed irradiation strategy was developed, in which the samples were repeatedly heated within short intervals of time (about 27 s) at the maximum microwave power. A significant reduction of the total time of irradiation was observed in reactions carried out under the pulsed scheme, showing the kinetic advantages of using microwaves in emulsion polymerization processes.

Graft polymerization of guar gum with acryl amide irradiated by microwaves for colonic drug delivery.

Science.gov (United States)

Shahid, Muhammad; Bukhari, Shazia Anwer; Gul, Yousra; Munir, Hira; Anjum, Fozia; Zuber, Mohammad; Jamil, Tahir; Zia, Khalid Mahmood

2013-11-01

This article is aimed to discuss the modification of guar gum through microwave irradiation by varying the time of irradiation. The characterization of the modified products was carried out using FTIR spectroscopic analysis. The FT-IR spectrum of the pure guar gum (GG) sample showed a broad peak at 3298 cm(-1) while the modified GG sample displayed a peak at 1541 cm(-1) which was absent in the crude sample. The X-ray diffraction (XRD) analysis confirmed the increase in crystallinity due to grafting of the sample with polyacrylamide (GG-g-PAM). Scanning electron microscope (SEM) images revealed that granular form of guar gum was changed into fibrillar structure after grafting. Thermo-gravimetric analysis of the modified samples was also carried out and discussed. The role of guar gum as a matrix for controlled release of drug triamcinolone was evaluated. The GG-acrylamide grafted samples presented a correlation between drug release and time of microwave exposure. The results revealed that such modified product has potential applications in colonic drug delivery system. Copyright © 2013 Elsevier B.V. All rights reserved.

Studies of deep levels in He+-irradiated silicon

International Nuclear Information System (INIS)

Schmidt, D.C.; Barbot, J.F.; Blanchard, C.

1997-01-01

Deep levels created in n-epitaxial silicon by alpha particle irradiation in the dose range from 10 9 to 10 13 particles/cm 2 have been investigated by the deep level transient spectroscopy technique and capacitance-voltage profiling. Under low fluence irradiation at least four main electron traps have been observed. With further increase in irradiation fluence, two new levels located at E c -0.56 eV and E c -0.64 eV appear on the high-temperature side of the DLTS signal. The slope change observed in the amplitude variations of the singly negative charge state of the divacancy versus the dose takes place when these two new levels appear. This suggests that both are multivacancy-related defects. After annealing at 350 C for 15 min, all electron traps have disappeared. Moreover, no shallow levels are created during the annealing. (orig.)

Irradiation damage behavior of low alloy steel wrought and weld materials

International Nuclear Information System (INIS)

Stofanak, R.J.; Poskie, T.J.; Li, Y.Y.; Wire, G.L.

1993-01-01

A study was undertaken to evaluate the irradiation damage response of several different types of low alloy steel: vintage type ASTM A302 Grade B (A302B) plates and welds containing different Ni and Cu concentrations, 3.5% Ni steels similar to ASTM A508 Class 4, welds containing about 1% Ni (similar to type 105S), and 3.5% Ni steels with ''superclean'' composition. All materials were irradiated at several different irradiation damage levels ranging from 0.0003 to 0.06 dpa at 232C (450F). Complete Charpy V-notch impact energy transition temperature curves were generated for all materials before and after irradiation to determine transition temperature at 4IJ (30 ft-lb) or 47J (35 ft-lb) and the upper shelf energy. Irradiation damage behavior was measured by shift in Charpy 41J or 47J transition temperature (ΔTT4 41J or ΔTT 47J ) and lowering of upper shelf Charpy energy at a given irradiation damage level. It was found that chemical composition greatly influenced irradiation damage behavior; highest irradiation damage (greatest ΔTT) was found in an A302B type weld containing 1.28% Ni and 0.20% Cu while the least damage was found in 3.5% Ni, 0.05% Cu, superclean wrought materials. Combination of Ni and Cu was found to affect irradiation damage behavior at higher irradiation damage levels in the A302B welds where the 1.28% Ni, 0.20% Cu weld showed more damage than a 0.60% Ni, 0.31% Cu weld. For the 3.5% Ni steels, fabrication influenced irradiation behavior in that a silicon (Si) killed material showed greater irradiation damage than a low silicon material. In general, the 3.5% Ni materials with low copper showed less irradiation damage than the A302B materials

An Evaluation of Fracture Toughness of Vinyl Ester Composites Cured under Microwave Conditions

Science.gov (United States)

Ku, H.; Chan, W. L.; Trada, M.; Baddeley, D.

2007-12-01

under ambient conditions. Higher power microwaves, 540 and 720 W with shorter duration of exposure are used to cure the composites. Short-bar method of fracture toughness measurement was used to perform the tests. Plastic (PVC) re-usable molds were designed and manufactured for producing the test samples. The results show that the fracture toughness of specimens cured by microwave conditions are generally higher than those cured under ambient conditions, provided the power level and duration of microwave irradiation are properly and optimally selected.

Facile preparation of super-hydrophilic poly(ethylene terephthalate) fabric using dilute sulfuric acid under microwave irradiation

Energy Technology Data Exchange (ETDEWEB)

Xu, Fang [College of Textiles and Garments, Southwest University, Chongqing 400715 (China); Chongqing Engineering Research Center of Biomaterial Fiber and Modern Textile, Chongqing 400715 (China); Zhang, Guangxian, E-mail: zgx656472@sina.com.cn [College of Textiles and Garments, Southwest University, Chongqing 400715 (China); Chongqing Engineering Research Center of Biomaterial Fiber and Modern Textile, Chongqing 400715 (China); Zhang, Fengxiu [College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); Zhang, Yuansong [College of Textiles and Garments, Southwest University, Chongqing 400715 (China); Chongqing Engineering Research Center of Biomaterial Fiber and Modern Textile, Chongqing 400715 (China)

2015-09-15

Highlights: • A durable super-hydrophilic PET fabric was prepared using dilute H{sub 2}SO{sub 4} under microwave irradiation. • Dilute sulfuric acid was gradually concentrated enough to sulfonate PET fabric. • Microwave irradiation made PET fabric modification highly efficient. • The mechanical properties of modified PET fibers were kept well. • The method was novel, rapid, and eco-friendly. - Abstract: The hydrophilicity of a poly(ethylene terephthalate) (PET) fabric was greatly modified by using dilute sulfuric acid, which gradually became concentrated enough to sulfonate the fabric when microwave irradiation (MW) was applied. The modified PET fabric was super-hydrophilic. Modifying the fabric caused the water contact angle to decrease from 132.46 (for the unmodified fabric) to 0°, the water absorption rate to increase from 36.45 to 119.78%, and the capillary rise height to increase from 0.4 to 14.4 cm. The hydrophilicity of the modified PET fabric was not affected by washing it many times. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses showed that there were sulfonic acid groups on the modified fibers. Almost no difference between the surfaces of the unmodified and modified PET fibers was found using scanning electron microscopy. Analysis by differential scanning calorimetry showed that the unmodified and modified fabrics had similar thermostabilities. X-ray diffraction analysis of the crystalline structures of the unmodified and modified fibers showed that they were almost the same. The strength, elasticity, and rigidity of the unmodified fabric were retained by the modified fabric. The modified fabric had better dyeing properties than the unmodified fabric.

Regeneration of carbon nanotubes exhausted with dye reactive red 3BS using microwave irradiation

International Nuclear Information System (INIS)

Wang Jun; Peng Xianjia; Luan Zhaokun; Zhao Changwei

2010-01-01

Carbon nanotubes (CNTs) exhausted with dye reactive red 3BS were regenerated by microwave irradiation under N 2 atmosphere. High regeneration efficiency was achieved and the regeneration efficiency reached 92.8% after four cycles regeneration. The decrease in adsorption capacity was suggested to be due to the deposition of decomposition residues in CNT pores, which blocked the carbon porosity and decreased the specific surface area.

Effects of Low-Level Laser Irradiation on the Pathogenicity of Candida albicans: In Vitro and in Vivo Study

NARCIS (Netherlands)

Seyedmousavi Tasieh, S.; Hashemi, S.J.; Rezaie, S.; Fateh, M.; Djavid, G.E.; Zibafar, E.; Morsali, F.; Zand, N.; Alinaghizadeh, M.; Ataie-Fashtami, L.

2014-01-01

Abstract Objective: The purpose of this study was to evaluate the effects of low-level laser irradiation (LLLI) on the in vitro growth characteristics and in vivo pathogenicity of Candida albicans in a murine model in the absence of a photosensitizer. Background data: C. albicans is an opportunistic

Microwave sintering of Ag-nanoparticle thin films on a polyimide substrate

Energy Technology Data Exchange (ETDEWEB)

Fujii, S., E-mail: fujii.s.ap@m.titech.ac.jp [Department of Applied Chemistry, Tokyo Institute of Technology, Tokyo 152-8522 (Japan); Department of Information and Communication System Engineering, National Institute of Technology, Okinawa College, Nago, Okinawa 905-2192 (Japan); Kawamura, S.; Maitani, M. M.; Suzuki, E.; Wada, Y. [Department of Applied Chemistry, Tokyo Institute of Technology, Tokyo 152-8522 (Japan); Mochizuki, D. [Interdisciplinary Cluster for Cutting Edge Research, Center for Energy and Environmental Science, Shinshu University, Ueda, Nagano 386-8567 (Japan)

2015-12-15

Ag-nanoparticle thin films on a polyimide substrate were subjected to microwave sintering by use of a single-mode waveguide applicator. A two-step sintering process was employed. First, at low conductivities of the film, the film sample was placed at the site of the maximum electric field and subjected to microwave irradiation. Second, when the conductivity of the film increased, the film sample was placed at the site of the maximum magnetic field and again subjected to microwave irradiation. The microwave sintering process was completed within 1.5 min, which is significantly lower than the time required for the oven heating process. The resulting conductivity of the film, albeit only 30% of that of the bulk material, was seven times that of a film annealed at the same temperature in a furnace. Scanning electron microscopy images revealed that the nanoparticles underwent both grain necking and grain growth during microwave sintering. In addition, this sintering process was equivalent to the oven heating process performed at a 50 °C higher annealing temperature. An electromagnetic wave simulation and a heat transfer simulation of the microwave sintering process were performed to gain a thorough understanding of the process.

Microwave sintering of Ag-nanoparticle thin films on a polyimide substrate

Directory of Open Access Journals (Sweden)

S. Fujii

2015-12-01

Full Text Available Ag-nanoparticle thin films on a polyimide substrate were subjected to microwave sintering by use of a single-mode waveguide applicator. A two-step sintering process was employed. First, at low conductivities of the film, the film sample was placed at the site of the maximum electric field and subjected to microwave irradiation. Second, when the conductivity of the film increased, the film sample was placed at the site of the maximum magnetic field and again subjected to microwave irradiation. The microwave sintering process was completed within 1.5 min, which is significantly lower than the time required for the oven heating process. The resulting conductivity of the film, albeit only 30% of that of the bulk material, was seven times that of a film annealed at the same temperature in a furnace. Scanning electron microscopy images revealed that the nanoparticles underwent both grain necking and grain growth during microwave sintering. In addition, this sintering process was equivalent to the oven heating process performed at a 50 °C higher annealing temperature. An electromagnetic wave simulation and a heat transfer simulation of the microwave sintering process were performed to gain a thorough understanding of the process.

Green chemistry: Efficient epoxides ring-opening with 1-butanol under microwave irradiation

International Nuclear Information System (INIS)

Garcia-Vidal, Jesus A.; Duran-Valle, Carlos J.; Ferrera-Escudero, Santiago

2006-01-01

Two activated carbons treated with mineral acids (HNO 3 and sulfonitric mixture) have been tested as acid catalysts in the epoxides (1,2-epoxyhexane and styrene oxide) ring-opening reaction with 1-butanol under microwave (MW) irradiation. The mayor obtained product is that resulting of the alcohol addition to the most substituted carbon in the epoxide ring. The most active catalyst is that treated with sulfonitric mixture. The use of a MW oven allows achieving to the complete conversion of styrene oxide in only 2 min

Green chemistry: Efficient epoxides ring-opening with 1-butanol under microwave irradiation

Energy Technology Data Exchange (ETDEWEB)

Garcia-Vidal, Jesus A. [Departamento de Quimica Inorganica, Facultad de Ciencias, Universidad de Extremadura, Campus Universitario, Avda. de Elvas, s/n, E-06071-Badajoz (Spain); Duran-Valle, Carlos J. [Departamento de Quimica Inorganica, Facultad de Ciencias, Universidad de Extremadura, Campus Universitario, Avda. de Elvas, s/n, E-06071-Badajoz (Spain)]. E-mail: carlosdv@unex.es; Ferrera-Escudero, Santiago [Departamento de Quimica Inorganica y Quimica Tecnica, Universidad Nacional de Educacion a Distancia, C/Senda del Rey, 9, E-28040 Madrid (Spain)

2006-06-30

Two activated carbons treated with mineral acids (HNO{sub 3} and sulfonitric mixture) have been tested as acid catalysts in the epoxides (1,2-epoxyhexane and styrene oxide) ring-opening reaction with 1-butanol under microwave (MW) irradiation. The mayor obtained product is that resulting of the alcohol addition to the most substituted carbon in the epoxide ring. The most active catalyst is that treated with sulfonitric mixture. The use of a MW oven allows achieving to the complete conversion of styrene oxide in only 2 min.

Experimental investigation on variation of physical properties of coal samples subjected to microwave irradiation

Science.gov (United States)

Hu, Guozhong; Yang, Nan; Xu, Guang; Xu, Jialin

2018-03-01

The gas drainage rate of low-permeability coal seam is generally less than satisfactory. This leads to the gas disaster of coal mine, and largely restricts the extraction of coalbed methane (CBM), and increases the emission of greenhouse gases in the mining area. Consequently, enhancing the gas drainage rate is an urgent challenge. To solve this problem, a new approach of using microwave irradiation (MWR) as a non-contact physical field excitation method to enhance gas drainage has been attempted. In order to evaluate the feasibility of this method, the methane adsorption, diffusion and penetrability of coal subjected to MWR were experimentally investigated. The variation of methane adsorbed amount, methane diffusion speed and absorption loop for the coal sample before and after MWR were obtained. The findings show that the MWR can change the adsorption property and reduce the methane adsorption capacity of coal. Moreover, the methane diffusion characteristic curves for both the irradiated coal samples and theoriginal coal samples present the same trend. The irradiated coal samples have better methane diffusion ability than the original ones. As the adsorbed methane decreases, the methane diffusion speed increases or remain the same for the sample subjected to MWR. Furthermore, compared to the original coal samples, the area of the absorption loop for irradiated samples increases, especially for the micro-pore and medium-pore stage. This leads to the increase of open pores in the coal, thus improving the gas penetrability of coal. This study provides supports for positive MWR effects on changing the methane adsorption and improving the methane diffusion and the gas penetrability properties of coal samples.

Microwave Accelerated Polymerization of 2-Phenyl-2-Oxazoline: Microwave or Temperature Effects?

NARCIS (Netherlands)

Hoogenboom, R.; Leenen, M.A.M.; Wiesbrock, F.D.; Schubert, U.S.

2005-01-01

Summary: Investigations regarding the cationic ring-opening polymerization of 2-phenyl-2-oxazoline under microwave irradiation and conventional heating are reported. This study was inspired by contradictory reports of the (non-)existence of non-thermal microwave effects that might accelerate the

Microwave Irradiated Copolymerization of Xanthan Gum with Acrylamide for Colonic Drug Delivery

Directory of Open Access Journals (Sweden)

Fozia Anjum

2015-01-01

Full Text Available Xanthan gum (XG is a polysaccharide produced by Xanthomonas campestris. The aim of the present study was to modify the xanthan by hydrolysis and grafting with acrylamide through microwave irradiation for different time intervals. Pure xanthan was partially hydrolyzed via enzymatic and chemical treatments followed by optional grafting. Proximate composition analysis, moisture content, and carbohydrate, protein, lipid, and fiber contents were determined. The morphological characteristics, structural composition, functional groups, and heat resistance of the crude, hydrolyzed, and grafted gum were evaluated using SEM, XRD, FTIR spectroscopy, and TGA. Morphological studies revealed that xanthan was broken down into smaller fragments as a result of hydrolysis and became somewhat smoother. Thermal analysis studies indicated a larger heat tolerance in the grafted xanthan relative to that of the native and hydrolyzed gums. Xanthan bound to a triamcinolone drug was evaluated in the context of controlled drug release. Controlled drug release correlated well with the exposure time to microwaves used to graft the gum.

Pre-1989 epidemiological surveys of low-level dose pre-conception irradiation

International Nuclear Information System (INIS)

Rose, K.S.B.

1990-01-01

Information from 59 pre-1989 epidemiological surveys concerning pre-conception irradiation at doses less than 0.1 Gy has been collated to determine whether any consistent patterns of health effects emerge. The surveys are considered in three groups: childhood malignancies, Down's syndrome and indicators of reproductive damage. Although a pattern is observed for Down's syndrome, no reliable associations are apparent for childhood malignancies (where all surveys pre-date the Gardner survey at Sellafield) or indications of reproductive damage. The twelve surveys of Down's syndrome in relation to maternal pre-conception irradiation received for medical reasons show a pattern consistent with a doubling dose of about 20 mGy. This doubling dose value is, however, not based on individual measurements of ovarian dose and is inconsistent with results from high-level dose surveys. There is no association between paternal irradiation and Down's syndrome. (author)

Impact of modified graphene and microwave irradiation on thermal stability and degradation mechanism of poly (styrene-co-methyl meth acrylate)

Energy Technology Data Exchange (ETDEWEB)

Zubair, Mukarram [Department of Environmental Engineering, University of Dammam, 31982 Dammam (Saudi Arabia); Shehzad, Farrukh [Department of Chemical Engineering, King Fahd University of Petroleum & Minerals, 31261 Dhahran, Saudi Arabia, (Saudi Arabia); Al-Harthi, Mamdouh A., E-mail: mamdouh@kfupm.edu.sa [Department of Chemical Engineering, King Fahd University of Petroleum & Minerals, 31261 Dhahran, Saudi Arabia, (Saudi Arabia); Center of Research Excellence in Nanotechnology, King Fahd University of Petroleum & Minerals, 31261 Dhahran (Saudi Arabia)

2016-06-10

Highlights: • Modified graphene imparts thermal stability to Poly (styrene-co-methyl methacrylate) [P(st-mma)]. • The thermal stability of P(st-mma) decreased with microwave irradiation. • The thermal stability of P(st-mma)/MG nanocomposites increased with irradiation time up to 10 min and decreased subsequently. • The degradation of P(st-mma) and P(st-mma)/MG is governed by random scission model. - Abstract: Poly (styrene-co-methyl methacrylate) [P(st-mma)] composite containing 0.1 wt% modified graphene (MG) was prepared via melt blending. MG was prepared by oxidation method using nitric acid. The P(st-mma) and P(st-mma)MG composite were irradiated using microwave radiation. The degradation mechanism and thermal stability of the irradiated and un-irradiated samples was analyzed by TGA. P(st-mma)MG showed high thermal stability. The average activation energy of thermal degradation was found to be 200 kJ/mol for P(st-mma), 214 kJ/mol for P(st-mma)MG. The activation energy was highest for 10 min irradiated nanocomposites indicating an improvement in stability. The degradation mechanism was investigated by comparing the master plots constructed using the experimental data with theoretical master plots of various kinetic models. The thermal degradation of P(st-mma) and P(st-mma)MG composite before and after irradiation governs the random scission mechanism. SEM and TEM micrographs showed improved interactions and degradation of composites after 10 min and 20 min irradiation respectively.

The low-cost microwave plasma sources for science and industry applications

Science.gov (United States)

Tikhonov, V. N.; Aleshin, S. N.; Ivanov, I. A.; Tikhonov, A. V.

2017-11-01

Microwave plasma torches proposed in the world market are built according to a scheme that can be called classical: power supply - magnetron head - microwave isolator with water load - reflected power meter - matching device - actual plasma torch - sliding short circuit. The total cost of devices from this list with a microwave generator of 3 kW in the performance, for example, of SAIREM (France), is about 17,000 €. We have changed the classical scheme of the microwave plasmathrone and optimised design of the waveguide channel. As a result, we can supply simple and reliable sources of microwave plasma (complete with our low-budget microwave generator up to 3 kW and a simple plasmathrone of atmospheric pressure) at a price from 3,000 €.

[Pulse flows of populations of cortical neurons under low-intensity pulsed microwave: interspike intervals].

Science.gov (United States)

Chizhenkova, R A

2014-01-01

Pulse flows of populations of cortical neurons were investigated on unanesthetized nonimmobilized rabbits prior, during, and after 1-min microwave irradiation (wavelength 37.5 cm, power density 0.5-1.0 mW/cm2) in continuous and pulse-modulated modes with a frequency of 5, 20 and 100 Hz. The changes in the characteristics of interspike intervals resulted from these exposures. The peculiarity of rearrangements of pulse flows and their dynamics was determined by modes of irradiation.

Use of in vitro gas production technique to evaluate the effects of microwave irradiation on sorghum (Sorghum bicolor and wheat (Triticum sp. nutritive values and fermentation characteristics

Directory of Open Access Journals (Sweden)

Farhad Parnian

2013-01-01

Full Text Available Effects of microwave irradiation (900 W for 3, 5 and 7 min on the nutritive value of sorghum and wheat grains were evaluated by in vitro gas production technique. Gas volume was recorded at 2, 4, 6, 8, 12, 16, 24, 36, 48, 72 and 96 h of incubation and kinetics of gas production were estimated using model: GP = A exp {– exp [1 + (be/A (LAG – t]}. Cumulative gas production at 24 h was used for estimation of metabolizable energy, net energy for lactation, short chain fatty acids, digestible organic matter and microbial protein. For sorghum grain, microwave irradiation increased cumulative gas production for most times of incubation linearly. Microwave treatments for 5 and 7 min increased the A fraction linearly in both cereal grain, whereas the maximum rate of gas production (b decreased linearly only in wheat grain. Microwave treatments for 3, 5 and 7 min increased (P<0.05 metabolizable energy, net energy for lactation and short chain fatty acids content of sorghum grain, but not of wheat grain. It was concluded that microwave irradiation changed the gas production parameters resulting changed ruminal fermentation characteristics that can be considered in ration formulation.

Daily low-dose/continuous capecitabine combined with neo-adjuvant irradiation reduces VEGF and PDGF-BB levels in rectal carcinoma patients

International Nuclear Information System (INIS)

Loven, David; B e'Ery, Einat; Yerushalmi, Rinat; Koren, Claude; Sulkes, Aaron; Fenig, Eyal; Lavi, Idit; Shaked, Yuval

2008-01-01

Metronomic low-dose chemotherapy regimen was found to have an antiangiogenic effect in tumors. However, its effect on levels of circulating pro-angiogenic and anti-angiogenic factors is not fully explored. Materials and methods. The levels of both VEGF and PDGF-BB were measured in three time points, in the serum of 32 rectal carcinoma patients receiving daily reduced-dose/continuous capecitabine in combination with preoperative pelvic irradiation. Results. We found a significant decrease in VEGF and PDGF-BB serum levels during the combination treatment (p<0.0001), followed by an increase in the successive rest-period (p<0.0001). In addition, substantial changes in platelets counts were observed during treatment in correlation with the changes of VEGF and PDGF-BB serum levels. Discussion. These results suggest that combined chemo-irradiation affect levels of pro-angiogenic factors during treatment, and may reflect an anti-angiogenic window induced during this treatment. The potential implications of this inducible phenomenon, including a possible clinical benefit from the administration of long lasting metronomic chemotherapy immediately following combined chemo-irradiation, would warrant further investigation

Immunobiological effect of bitemporal exposure of rabbits to microwaves

Energy Technology Data Exchange (ETDEWEB)

Bogolyubov, V.M.; Pershin, S.B.; Frenkel' , I.D.; Sidorov, V.D.; Galenchik, A.I.; Ponomarev, Yu.T.; Bobkova, A.S.; Kuz' min, S.N.; Moshiashvili, I.Ya.; Kozlova, N.N.; Korovkina, E.G.; Agibalov, Yu.V.

1987-01-01

The authors investigate the effects of microwave radiation on the immunological behavior of the thyroid and various hormones of rabbits. Irradiation was carried out on the heads of the animals. They were then divided into four groups depending on the period of exposure. The number of hemolysis-forming cells against sheep red blood cells and the concentration of serum immunoglobulins were determined. Levels of TSH, triiodothyronine, thyroxine, testosterone and prostaglandins in serum or blood plasma were determined by radioimmunoassay and the concentration of total 11-hydroxycorticosteroids in the adrenals and plasma were determined by fluorimetry. Microwave radiation of the temporo-parietal region of the head was found to decrease the number of background hemolysis-forming cells. An increase in glucocorticoid function was recorded. Thyroid function was depressed. The plasma 11-hydroxycorticosteroid level was significantly raised. It is concluded in general that microwave irradiation leads to activation of the hypothalamo-hypophyseo-adrenal system with consequent enhancement of the glucocorticoid function of the adrenal cortex and depression of thyroid function.

Structural and physico-mechanical properties of natural rubber/GTR composites devulcanized by microwaves: influence of GTR source and irradiation time

OpenAIRE

Colom Fajula, Xavier; Marin-Genesca, Marc; Mujal Rosas, Ramón María; Formela, Krzysztof; Cañavate Ávila, Francisco Javier

2018-01-01

Ground tire rubber from car and truck was modified using microwave irradiation at variable time. The irradiated ground tire rubber was used as filler in composites based on natural rubber. The composites, with high content of ground tire rubber, were prepared using an internal batch mixer and subsequently cross-linked at 160¿. The influence of the ground tire rubber source (car/truck) and irradiation time on structure, physico-mechanical behaviour, thermal properties and morphology of natural...

Features of transformation of impurity-defect complexes in СdTe:Сl under the influence of microwave radiation

Directory of Open Access Journals (Sweden)

Budzulyak S. I.

2014-08-01

Full Text Available High-resistance cadmium telluride single crystals are promising material for production of ionizing radiation detectors. To increase crystal resistance, they are doped with chlorine. The detector quality depends on uniformity of chlorine impurity distribution over crystal. It is known that low-dose microwave irradiation can homogenize impurity distribution in a specimen. In the present work, we made an attempt to improve the detector material quality by using such post-technological treatment, as well as to study state variation for impurity-defect complexes. To this end, the effect of microwave irradiation on transformation of impurity-defect complexes in CdTe:Cl single crystals was investigated using low-temperature photoluminescence. It is shown that activation of ClTe donor centers by microwave irradiation for 10 s and presence of VCd acceptor centers in the specimens under investigation effectively facilitate formation of (VNd–ClTe defect centers at which excitons are bound. Detailed investigations of the band form for donor-acceptor pairs (DAPs in CdTe:Cl single crystals made it possible to determine the Huang—Rhys factor (that characterizes electron-phonon interaction in CdTe:Cl DAPs as a function of microwave treatment duration. It is shown for single crystals with NCl = 5·1017 cm–3 and 5·1019 cm–3 that the Huang—Rhys factor grows with microwave irradiation dose. This is related to both homogenization of donor and acceptor centers distribution and increase of donor—acceptor spacing. It is shown that microwave irradiation of CdTe:Cl single crystals results in concentration reduction for separate cadmium vacancies VCd because of formation of (VNd—ClTe defect centers at which excitons are bound.

A low-cost, modular, microwave-linked, color TV inspection system

International Nuclear Information System (INIS)

Panda, N.C.

1991-01-01

This paper reports that many custom-built radiation-shielded CCTV inspection systems for nuclear facilities are available in the market. This author, however, could find no reference to units using low-cost nodular technology for wireless transmission and control of color CCTV signals in radiation environments. The system that was developed is a process control observation tool geared toward identifying locations ad volumes of accumulated in-cell solids. It also performs remote integrity assessments of tanks and pipe routings that are required by regulatory agencies. System highlights are: microwave transmission of video and control signals, low cost, low maintenance, and modular design. Use of standard components enables easy exchange of modules. Microwave transmission resolved the complications of a wired system while increasing reliability and safety. The video image is created by the remote in-cell color TV camera and transmitted by microwave out of the cell to TV monitors at consoles in non-radiation zones

Microwave Pretreatment for Thiourea Leaching for Gold Concentrate

Directory of Open Access Journals (Sweden)

Nag-Choul Choi

2017-10-01

Full Text Available In this research, we studied the use of microwave pretreatment to enhance the efficiency of Au leaching from gold concentrate. The gold concentrate was pretreated using microwaves with different irradiation time. The sample temperature was increased up to 950 °C by the microwave irradiation. A scanning electron microscope-energy dispersive spectrometer showed the evolution of microcracks and the reduction of sulfur on the mineral surface. X-ray diffraction data also showed the mineral phase shift from pyrite to hematite or pyrrhotite. A leaching test was conducted for the microwave-treated and untreated gold concentrates using thiourea. Although the thiourea leaching recovered 80% of Au from the untreated concentrate, from the treated concentration, the Au could be recovered completely. Au leaching efficiency increased as the microwave irradiation time increased, as well as with a higher composition of thiourea.

Microwave Irradiation Effect on the Dispersion and Thermal Stability of RGO Nanosheets within a Polystyrene Matrix

Directory of Open Access Journals (Sweden)

Edreese H. Alsharaeh

2014-07-01

Full Text Available Polystyrene-reduced graphene oxide (PSTY/RGO composites were prepared via the in situ bulk polymerization method using two different preparation techniques. The general approach is to use microwave irradiation (MWI to enhance the exfoliation and the dispersion of RGO nanosheets within the PSTY matrix. In the first approach, a mixture of GO and styrene monomers (STY were polymerized using a bulk polymerization method facilitated by microwave irradiation (MWI to obtain R-(GO-PSTY composites. In the second approach, a mixture of RGO and STY monomers were polymerized using a bulk polymerization method to obtain RGO-(PSTY composites. The two composites were characterized by FTIR, 1H-NMR, XRD, SEM, HRTEM, TGA and DSC. The results indicate that the composite obtained using the first approach, which involved MWI, had a better morphology and dispersion with enhanced thermal stability, compared with the composites prepared without MWI. Moreover, DSC results showed that the Tg value of the composites after loading the RGO significantly increased by 24.6 °C compared to the neat polystyrene.

Electron beam irradiation facility for low to high dose irradiation applications

International Nuclear Information System (INIS)

Petwal, V.C.; Wanmode, Yashwant; Verma, Vijay Pal; Bhisikar, Abhay; Dwivedi, Jishnu; Shrivastava, P.; Gupta, P.D.

2013-01-01

Electron beam based irradiation facilities are becoming more and more popular over the conventional irradiator facilities due to many inherent advantages such as tunability of beam energy, availability of radiation both in electron mode and X-ray mode, wide range of the dose rate, control of radiation from a ON-OFF switch and other safety related merits. A prototype experimental facility based on electron accelerator has been set-up at RRCAT to meet the low-dose, medium dose and high-dose requirements for radiation processing of food, agricultural and medical products. The facility can be operated in the energy range from 7-10 MeV at variable power level from 0.05-3 kW to meet the dose rate requirement of 100 Gy to kGy. The facility is also equipped with a Bremsstrahlung converter optimized for X-ray irradiation at 7.5 MV. Availability of dose delivery in wide range with precision control and measurement has made the facility an excellent tool for researchers interested in electron/X-ray beam irradiation. A precision dosimetry lab based on alanine EPR and radiochromic film dosimetry system have been established to characterize the radiation field and precise dose measurements. Electron beam scattering technique has been developed to achieve low dose requirement for EB irradiation of various seeds such as groundnut, wheat, soybeans, moong beans, black gram etc. for mutation related studies. This paper describes various features of the facility together with the dosimetric measurements carried out for qualification of the facility and recent irradiation experiments carried out using this facility. (author)

A novel property of gold nanoparticles: Free radical generation under microwave irradiation

International Nuclear Information System (INIS)

Paudel, Nava Raj; Shvydka, Diana; Parsai, E. Ishmael

2016-01-01

Purpose: Gold nanoparticles (GNPs) are known to be effective mediators in microwave hyperthermia. Interaction with an electromagnetic field, large surface to volume ratio, and size quantization of nanoparticles (NPs) can lead to increased cell killing beyond pure heating effects. The purpose of this study is to explore the possibility of free radical generation by GNPs in aqueous media when they are exposed to a microwave field. Methods: A number of samples with 500 mM 5,5-dimethyl-1-pyrroline N-oxide (DMPO) in 20 ppm GNP colloidal suspensions were scanned with an electron paramagnetic resonance (EPR)/electron spin resonance spectrometer to generate and detect free radicals. A fixed (9.68 GHz) frequency microwave from the spectrometer has served for both generation and detection of radicals. EPR spectra obtained as first derivatives of intensity with the spectrometer were double integrated to get the free radical signal intensities. Power dependence of radical intensity was studied by applying various levels of microwave power (12.5, 49.7, and 125 mW) while keeping all other scan parameters the same. Free radical signal intensities from initial and final scans, acquired at the same power levels, were compared. Results: Hydroxyl radical (OH⋅) signal was found to be generated due to the exposure of GNP–DMPO colloidal samples to a microwave field. Intensity of OH⋅ signal thus generated at 12.5 mW microwave power for 2.8 min was close to the intensity of OH⋅ signal obtained from a water–DMPO sample exposed to 1.5 Gy ionizing radiation dose. For repeated scans, higher OH⋅ intensities were observed in the final scan for higher power levels applied between the initial and the final scans. Final intensities were higher also for a shorter time interval between the initial and the final scans. Conclusions: Our results observed for the first time demonstrate that GNPs generate OH⋅ radicals in aqueous media when they are exposed to a microwave field. If OH�

A novel property of gold nanoparticles: Free radical generation under microwave irradiation.

Science.gov (United States)

Paudel, Nava Raj; Shvydka, Diana; Parsai, E Ishmael

2016-04-01

Gold nanoparticles (GNPs) are known to be effective mediators in microwave hyperthermia. Interaction with an electromagnetic field, large surface to volume ratio, and size quantization of nanoparticles (NPs) can lead to increased cell killing beyond pure heating effects. The purpose of this study is to explore the possibility of free radical generation by GNPs in aqueous media when they are exposed to a microwave field. A number of samples with 500 mM 5,5-dimethyl-1-pyrroline N-oxide (DMPO) in 20 ppm GNP colloidal suspensions were scanned with an electron paramagnetic resonance (EPR)/electron spin resonance spectrometer to generate and detect free radicals. A fixed (9.68 GHz) frequency microwave from the spectrometer has served for both generation and detection of radicals. EPR spectra obtained as first derivatives of intensity with the spectrometer were double integrated to get the free radical signal intensities. Power dependence of radical intensity was studied by applying various levels of microwave power (12.5, 49.7, and 125 mW) while keeping all other scan parameters the same. Free radical signal intensities from initial and final scans, acquired at the same power levels, were compared. Hydroxyl radical (OH⋅) signal was found to be generated due to the exposure of GNP-DMPO colloidal samples to a microwave field. Intensity of OH⋅ signal thus generated at 12.5 mW microwave power for 2.8 min was close to the intensity of OH⋅ signal obtained from a water-DMPO sample exposed to 1.5 Gy ionizing radiation dose. For repeated scans, higher OH⋅ intensities were observed in the final scan for higher power levels applied between the initial and the final scans. Final intensities were higher also for a shorter time interval between the initial and the final scans. Our results observed for the first time demonstrate that GNPs generate OH⋅ radicals in aqueous media when they are exposed to a microwave field. If OH⋅ radicals can be generated close to

A novel property of gold nanoparticles: Free radical generation under microwave irradiation

Energy Technology Data Exchange (ETDEWEB)

Paudel, Nava Raj, E-mail: nrpaudel@yahoo.com [Department of Radiation Oncology, The University of Toledo Medical Center, Toledo, Ohio 43614 and Department of Radiation Oncology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205 (United States); Shvydka, Diana; Parsai, E. Ishmael [Department of Radiation Oncology, The University of Toledo Medical Center, Toledo, Ohio 43614 (United States)

2016-04-15

Purpose: Gold nanoparticles (GNPs) are known to be effective mediators in microwave hyperthermia. Interaction with an electromagnetic field, large surface to volume ratio, and size quantization of nanoparticles (NPs) can lead to increased cell killing beyond pure heating effects. The purpose of this study is to explore the possibility of free radical generation by GNPs in aqueous media when they are exposed to a microwave field. Methods: A number of samples with 500 mM 5,5-dimethyl-1-pyrroline N-oxide (DMPO) in 20 ppm GNP colloidal suspensions were scanned with an electron paramagnetic resonance (EPR)/electron spin resonance spectrometer to generate and detect free radicals. A fixed (9.68 GHz) frequency microwave from the spectrometer has served for both generation and detection of radicals. EPR spectra obtained as first derivatives of intensity with the spectrometer were double integrated to get the free radical signal intensities. Power dependence of radical intensity was studied by applying various levels of microwave power (12.5, 49.7, and 125 mW) while keeping all other scan parameters the same. Free radical signal intensities from initial and final scans, acquired at the same power levels, were compared. Results: Hydroxyl radical (OH⋅) signal was found to be generated due to the exposure of GNP–DMPO colloidal samples to a microwave field. Intensity of OH⋅ signal thus generated at 12.5 mW microwave power for 2.8 min was close to the intensity of OH⋅ signal obtained from a water–DMPO sample exposed to 1.5 Gy ionizing radiation dose. For repeated scans, higher OH⋅ intensities were observed in the final scan for higher power levels applied between the initial and the final scans. Final intensities were higher also for a shorter time interval between the initial and the final scans. Conclusions: Our results observed for the first time demonstrate that GNPs generate OH⋅ radicals in aqueous media when they are exposed to a microwave field. If OH�

Microwave-assisted hydrothermal synthesis of lead zirconate fine powders

Directory of Open Access Journals (Sweden)

Apinpus Rujiwatra

2011-01-01

Full Text Available A rapid synthesis of lead zirconate fine powders by microwave-assisted hydrothermal technique is reported. The influences of type of lead precursor, concentration of potassium hydroxide mineraliser, applied microwave power and irradiation time are described. The synthesised powders were characterised by powder X-ray diffraction, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopic microanalysis and light scattering technique. The merits of the microwave application in reducing reaction time and improving particle mono-dispersion and size uniformity as well as the drawbacks, viz. low purity of the desired phase and increasing demand of mineraliser, are discussed in relation to conventional heating method.

Bioconversion of different sizes of microcrystalline cellulose pretreated by microwave irradiation with/without NaOH

International Nuclear Information System (INIS)

Peng, Huadong; Chen, Hongzhang; Qu, Yongshui; Li, Hongqiang; Xu, Jian

2014-01-01

Highlights: • High concentration of alkali or temperature was necessary in cellulose degradation. • Effects of alkali pretreatment could be enhanced with the addition of microwave irradiation. • The structures diversities of microcrystalline cellulose were eliminated in the fermentation. • The significance of particle size and treat condition varied with reaction time. - Abstract: The process of microwave irradiation (MWI) pretreatment on microcrystalline cellulose (MCC) with different sizes with/without NaOH was investigated on the variation of the ratio of degradated solid residue (R DS ), particle size, crystallinity index (CrI), crystallite size (Sc) and specific surface area (SSA). High concentration of alkali or high temperature was necessary in dissolving or decomposing the cellulose. Appropriate pretreatment severity eliminated the effects of structural diversities in feedstocks, which led to convergence in the ethanol fermentation. After the reaction proceeded to 120 h, the samples could be converted to glucose completely and the highest ethanol yield of the theoretical was 58.91% for all the samples pretreated by the combined treatment of MWI and NaOH. In addition, the statistical analysis implied that when reaction time got to 24 h, particle size and pretreatment condition affected much more significant than other factors

Microwave irradiation effects on vermicasts potency, and plant growth and antioxidant activity in seedlings of Chinese cabbage (Brassica rapa subsp. pekinensis

Directory of Open Access Journals (Sweden)

Lord Abbey

2017-04-01

Full Text Available Vermicasts is rich in beneficial microorganisms and plant growth factors. Unlike soils, the effect of microwave irradiation (MWI on vermicasts potency has not been reported. This study investigated MWI effects on vermicasts potency, plant growth and biochemical activity in Chinese cabbage ‘Bilko’ seedlings. Fresh, moist vermicasts were microwaved at power output levels: 0, 100, 200, 300, 400 and 800 Watts (W. Water loss, nutrients and total aerobic plate content were assessed. A complete randomized design greenhouse experiment was used to evaluate seedlings growth performance and tissue bioactivity. Water loss increased from 5 mg/g (0 W to 215 mg/g (800 W. Total dissolved solids and electrical conductivity of the vermicasts gradually increased with an increase in MWI power output level from 0 to 200 W. This was followed by a steep rise through treatment 300 W and a peak at 400 W. Total nitrogen and nitrate decreased, while ammonia-nitrogen and nitrite-nitrogen increased at higher power levels. Similarly, phosphorus, potassium, magnesium, calcium, manganese, barium and molybdenum contents increased while sodium and barium remained fairly constant. However, MWI irradiation reduced total aerobic plate count by ≥50%. Plant growth and biomass were increased by the 400 W and 800 W MWI treatments. Antioxidant activity was highest in 200, 400 and 800 W treated plants. Collectively the finding indicated that the 400 W treatment increased the bioavailability of nutrients, and represents the best option for plant growth enhancement and improved antioxidant activity.

Microwave Enhanced Reactive Distillation

NARCIS (Netherlands)

Altman, E.

2011-01-01

The application of electromagnetic irradiation in form of microwaves (MW) has gathered the attention of the scientific community in recent years. MW used as an alternative energy source for chemical syntheses (microwave chemistry) can provide clear advantages over conventional heating methods in

Photobiostimulation on chondrocytes proliferation in different concentration of fetal bovine serum under low-level laser irradiation

Science.gov (United States)

Zheng, Liqin; Wang, Yuhua; Qiu, Caimin; Chen, Jianlin; Yang, Hongqin; Zhang, Yanding; Xie, Shusen

2015-03-01

The aim of this in vitro study was to evaluate the influence of low-level laser irradiation (LLLI) on the chondrocytes proliferation cultured in different concentration of fetal bovine serum (FBS) using 658 nm, 785 nm and 830 nm diode lasers. The role of energy density (10-70 mJ·cm-2) on chondrocytes proliferation following irradiation with 658 nm laser for 2 days was firstly investigated to find out the best laser energy density. Then the effect of LLLI on the proliferation of chondrocytes cultured with fetal bovine serum at 0%, 2%, 5% and 10% was also evaluated. The results showed that there was no or little photobiostimulation on the proliferation of chondrocytes cultured with 0% FBS and 10% FBS; the cell proliferation at 2% and 5% FBS was significantly modulated by LLLI.

The Screening of Genes Sensitive to Long-Term, Low-Level Microwave Exposure and Bioinformatic Analysis of Potential Correlations to Learning and Memory

Institute of Scientific and Technical Information of China (English)

ZHAO Ya Li; LI Ying Xian; MA Hong Bo; LI Dong; LI Hai Liang; JIANG Rui; KAN Guang Han; YANG Zhen Zhong; HUANG Zeng Xin

2015-01-01

Objective To gain a better understanding of gene expression changes in the brain following microwave exposure in mice. This study hopes to reveal mechanisms contributing to microwave-induced learning and memory dysfunction. Methods Mice were exposed to whole body 2100 MHz microwaves with specific absorption rates (SARs) of 0.45 W/kg, 1.8 W/kg, and 3.6 W/kg for 1 hour daily for 8 weeks. Differentially expressing genes in the brains were screened using high-density oligonucleotide arrays, with genes showing more significant differences further confirmed by RT-PCR. Results The gene chip results demonstrated that 41 genes (0.45 W/kg group), 29 genes (1.8 W/kg group), and 219 genes (3.6 W/kg group) were differentially expressed. GO analysis revealed that these differentially expressed genes were primarily involved in metabolic processes, cellular metabolic processes, regulation of biological processes, macromolecular metabolic processes, biosynthetic processes, cellular protein metabolic processes, transport, developmental processes, cellular component organization, etc. KEGG pathway analysis showed that these genes are mainly involved in pathways related to ribosome, Alzheimer's disease, Parkinson's disease, long-term potentiation, Huntington's disease, and Neurotrophin signaling. Construction of a protein interaction network identified several important regulatory genes including synbindin (sbdn), Crystallin (CryaB), PPP1CA, Ywhaq, Psap, Psmb1, Pcbp2, etc., which play important roles in the processes of learning and memory. Conclusion Long-term, low-level microwave exposure may inhibit learning and memory by affecting protein and energy metabolic processes and signaling pathways relating to neurological functions or diseases.

VOC removal by microwave, electron beam and catalyst technique

International Nuclear Information System (INIS)

IghigeanuI, D.; Martin, D.; OproiuI, C.; Manaila, E.; Craciun, G.; Calinescu, I.; Zissulescu, E.

2007-01-01

A hybrid technique, developed for VOCs removal using microwave (MW) treatment, electron beam (EB) irradiation and catalyst method, is presented. Two hybrid laboratory installations, developed for the study of air pollution control by combined EB irradiation, MW irradiation and catalyst, are described. Air loaded with toluene was treated at different MW power levels, water content, flow rates, and different irradiation modes, separately and combined with MW and EB. Also, simultaneous EB and MW irradiation method was applied to SO 2 and NO x removal. Real synergy effects between EB induced NTP, MW induced NTP and catalysis can be observed

A comparison of γ-irradiation and microwave treatments on the lipids and microbiological pattern of beef liver

Directory of Open Access Journals (Sweden)

Daw, Z. Y.

2001-02-01

Full Text Available The effects of γ-irradiation (0, 2.5, 5 and, 10 kGy and microwaves (generated from an oven at low and defrost settings for 0.5, 1 and 2 min treatments on the chemical composition and microbiological aspects of beef liver samples were studied. The chemical and microbiological analyses were performed on the non-treated and treated beef liver immediately after treatments and during frozen storage (-18ºC for 3 months. The chemical analyses of beef liver lipids showed that acid, peroxide and TBA values were slightly increased after irradiation treatments and also during frozen storage (-18ºC. On the contrary, iodine value of the treated beef liver was decreased. Irradiation treatments remarkably reduced the total bacterial counts in beef liver. The percent reduction of bacterial load for beef liver exposed to microwaves generated from an oven at defrost mode for 2 min and after 3 months at -18ºC was 62%. The bacterial load for beef liver exposed to γ-irradiation at 10 kGy after 3 months at -18ºC was decreased by 98%. Hence, γ-irradiation treatment was far better than microwave treatment for reduction of the associated microorganisms with beef liver. Salmonellae was not detected in non-irradiated and irradiated beef liver throughout the storage period.Se estudiaron los efectos de los tratamientos por irradiación γ (0, 2.5, 5 y 10 kGy y microondas (generados en un horno a nivel bajo y de descongelación durante 0.5, 1 y 2 min sobre la composición química y aspectos microbiológicos de las muestras de hígado de vaca. Los análisis químicos y microbiológicos se llevaron a cabo en hígado de vaca tratado y no tratado al inicio y durante el almacenamiento en congelador a -18ºC durante 3 meses. Los análisis químicos de los lípidos de hígado de vaca mostraron que los índices de acidez, peróxido y TBA se incrementaron ligeramente después de los tratamientos por irradiación y durante el almacenamiento en congelador (-18�

The formation of hollow poly(methyl methacrylate)/multiwalled carbon nanotube nanocomposite cylinders by microwave irradiation

International Nuclear Information System (INIS)

Wang Huan; Hu Xijun; Ka Ming Ng; Feng Jiyun

2009-01-01

Poly(methyl methacrylate) (PMMA)/multiwalled carbon nanotube (MWCNT) nanocomposite particles with 1, 2 and 4 wt% of MWCNTs were prepared by mechanical grinding of PMMA and MWCNT powders in a mortar at room temperature. Both scanning electron microscopy and Raman scattering characterizations revealed that these nanocomposite particles consist of a PMMA core and a MWCNT shell. The PMMA/MWCNT nanocomposite particles were used to fabricate the corresponding nanocomposites in the form of a hollow cylinder with various diameters and heights under 700 W microwave irradiation within 1 min. A mechanism for the fast microwave assisted forming process is proposed. These experimental results may lead to a new technology for forming hollow polymeric articles that is different from the conventional injection and blowing process.

Microwave-irradiated preparation of reduced graphene oxide-Ni nanostructures and their enhanced performance for catalytic reduction of 4-nitrophenol

Energy Technology Data Exchange (ETDEWEB)

Qiu, Hanxun, E-mail: hxqiu@usst.edu.cn; Qiu, Feilong; Han, Xuebin; Li, Jing; Yang, Junhe, E-mail: jhyang@usst.edu.cn

2017-06-15

Highlights: • Nickel nanoparticle-decorated reduced graphene-oxide nanostructures were prepared by an environmentally friendly, one-pot strategy via an efficient microwave irradiation approach. • Upon microwave irradiation, the composites could be prepared within only a few hundred seconds, much faster than using the widely used traditional hydrothermal methods that may take tens of hours generally. • The nanostructure exhibits superior catalytic activity and selectivity towards transforming the highly toxic nitroaromatic compounds to industrially useful intermediates • The corresponding kinetic reaction rate constant (κ) is even four-fold compared to pure Ni nanoparticles. - Abstract: Here we report an environmentally friendly, one-pot strategy toward preparation of nickel nanoparticle-decorated reduced graphene-oxide (Ni-RGO) nanostructures, by employing Ni(AC){sub 2} as nickel source and ethylene glycol as both solvent and reducing agent via a facile microwave irradiation heating approach. The results show that Ni nanoparticles with an average diameter of around 40 nm are homogeneously anchored onto the surface of RGO sheets. As compared to the pure Ni nanoparticles and RGO sheets, Ni-RGO composites with over 64 wt% loading of Ni nanoparticles possess superior catalytic activities and selectivity toward the reduction of 4-nitrophenol. The corresponding kinetic reaction rate constant (defined as κ) is even four-fold compared to pure Ni nanoparticles. Such promising composites show great potential for friendly treatment of industrial waste containing nitrophenol in a simple, sustainable and green way.

Microwave-irradiated preparation of reduced graphene oxide-Ni nanostructures and their enhanced performance for catalytic reduction of 4-nitrophenol

International Nuclear Information System (INIS)

Qiu, Hanxun; Qiu, Feilong; Han, Xuebin; Li, Jing; Yang, Junhe

2017-01-01

Highlights: • Nickel nanoparticle-decorated reduced graphene-oxide nanostructures were prepared by an environmentally friendly, one-pot strategy via an efficient microwave irradiation approach. • Upon microwave irradiation, the composites could be prepared within only a few hundred seconds, much faster than using the widely used traditional hydrothermal methods that may take tens of hours generally. • The nanostructure exhibits superior catalytic activity and selectivity towards transforming the highly toxic nitroaromatic compounds to industrially useful intermediates • The corresponding kinetic reaction rate constant (κ) is even four-fold compared to pure Ni nanoparticles. - Abstract: Here we report an environmentally friendly, one-pot strategy toward preparation of nickel nanoparticle-decorated reduced graphene-oxide (Ni-RGO) nanostructures, by employing Ni(AC) 2 as nickel source and ethylene glycol as both solvent and reducing agent via a facile microwave irradiation heating approach. The results show that Ni nanoparticles with an average diameter of around 40 nm are homogeneously anchored onto the surface of RGO sheets. As compared to the pure Ni nanoparticles and RGO sheets, Ni-RGO composites with over 64 wt% loading of Ni nanoparticles possess superior catalytic activities and selectivity toward the reduction of 4-nitrophenol. The corresponding kinetic reaction rate constant (defined as κ) is even four-fold compared to pure Ni nanoparticles. Such promising composites show great potential for friendly treatment of industrial waste containing nitrophenol in a simple, sustainable and green way.

Treatment options for low-level radiologically contaminated ORNL filtercake

International Nuclear Information System (INIS)

Lee, Hom-Ti; Bostick, W.D.

1996-04-01

Water softening sludge (>4000 stored low level contaminated drums; 600 drums per year) generated by the ORNL Process Waste Treatment Plant must be treated, stabilized, and placed in safe storage/disposal. The sludge is primarily CaCO 3 and is contaminated by low levels of 90 Sr and 137 Cs. In this study, microwave sintering and calcination were evaluated for treating the sludge. The microwave melting experiments showed promise: volume reductions were significant (3-5X), and the waste form was durable with glass additives (LiOH, fly ash). A commercial vendor using surrogate has demonstrated a melt mineralization process that yields a dense monolithic waste form with a volume reduction factor (VR) of 7.7. Calcination of the sludge at 850-900 C yielded a VR of 2.5. Compaction at 4500 psi increased the VR to 4.2, but the compressed form is not dimensionally stable. Addition of paraffin helped consolidate fines and yielded a VR of 3.5. In conclusion, microwave melting or another form of vitrification is likely to be the best method; however for immediate implementation, the calculation/compaction/waxing process is viable

USDOE activities in low-level radioactive waste treatment

International Nuclear Information System (INIS)

Vath, J.E.

1981-01-01

This paper describes current research, development and demonstration (R, D and D) programs sponsored by the US Department of Energy in the area of low-level radioactive waste treatment. During the twelve month period ending September 30, 1981, 14 prime US Department of Energy contractors were involved with over 40 low-level radioactive waste disposal technology projects. Three specific projects or task areas have been selected for discussion to illustrate new and evolving technologies, and application of technology developed in other waste management areas to low-level waste treatment. The areas to be discussed include a microwave plasma torch incinerator, application of waste vitrification, and decontamination of metal waste by melting

A Convenient Synthesis of Conjugated Acetylenic Ketones by Copper(l)-Catalyzed under Microwave Irradiation

Institute of Scientific and Technical Information of China (English)

WANG; JinXian

2001-01-01

Alkynyl ketones are useful precursors and intermediates in synthetic organic chemistry1 and has evoked considerable interest. A number of methods for the synthesis of conjugated acetylenic ketones involve the reaction a metal acetylide with an acyl chlorides or another carboxylic acid derivative have been developed 2. Recently, the synthesis of α, β-conjugated acetylenic ketones catalyzed by Pd(Ⅱ) or by copper(Ⅰ)pd(Ⅱ) reaction of 1-alkynes and acyl chlorides have been described. The acylation of terminal alkynes by acyl chlorides in the presence of catalytic amounts copper(Ⅰ) salts leading to α, β-conjugated acetylenic ketones has also been reported. However, many of these reactions suffer from lack of high pressure (17 atm), long reaction time (30 h)and require low temperatures (-78℃). Our work involves the synthesis of conjugated acetylenic ketones via the reaction of terminal alkynes with aroyl chlorides in the presence of cuprous iodide under microwave irradiation conditions.……

A Convenient Synthesis of Conjugated Acetylenic Ketones by Copper(l)-Catalyzed under Microwave Irradiation

Institute of Scientific and Technical Information of China (English)

WANG JinXian; WEI BangGuo; ZHAO LianBiao; HU YuLai; KANG LiQing

2001-01-01

@@ Alkynyl ketones are useful precursors and intermediates in synthetic organic chemistry1 and has evoked considerable interest. A number of methods for the synthesis of conjugated acetylenic ketones involve the reaction a metal acetylide with an acyl chlorides or another carboxylic acid derivative have been developed 2. Recently, the synthesis of α, β-conjugated acetylenic ketones catalyzed by Pd(Ⅱ) or by copper(Ⅰ)pd(Ⅱ) reaction of 1-alkynes and acyl chlorides have been described. The acylation of terminal alkynes by acyl chlorides in the presence of catalytic amounts copper(Ⅰ) salts leading to α, β-conjugated acetylenic ketones has also been reported. However, many of these reactions suffer from lack of high pressure (17 atm), long reaction time (30 h)and require low temperatures (-78℃). Our work involves the synthesis of conjugated acetylenic ketones via the reaction of terminal alkynes with aroyl chlorides in the presence of cuprous iodide under microwave irradiation conditions.

Synthesis of tungsten oxide (W{sub 18}O{sub 49}) nanosheets utilizing EDTA salt by microwave irradiation method

Energy Technology Data Exchange (ETDEWEB)

Hariharan, V.; Parthibavarman, M. [Centre for Nanoscience and Technology, Department of Physics, Periyar University, Salem 636 011, Tamilnadu (India); Sekar, C., E-mail: Sekar2025@gmail.com [Centre for Nanoscience and Technology, Department of Physics, Periyar University, Salem 636 011, Tamilnadu (India); Department of Bioelectronics and Biosensors, Alagappa University, Karaikudi 630 003, Tamilnadu (India)

2011-04-07

Research highlights: > We have synthesized tungsten oxide (WO{sub 3-{delta}}) nanoparticles by microwave irradiation method for the first time using EDTA as surface modulator. The variation in stoichiometric oxygen content of the annealed samples clearly indicates the role of EDTA in reaction medium. The variation in oxygen content also modified the transparency of the end product confirming the change in optical conductivity. - Abstract: We report the synthesis of crystalline W{sub 18}O{sub 49} with nanosheet like morphology by low cost microwave irradiation method without employing hydrothermal process for the first time. Initially, WO{sub 3}.H{sub 2}O was synthesized using ethylenediaminetetraacetic acid (EDTA) as surface modulator. The product was annealed at 600 {sup o}C for 6 h in ambient atmosphere in order to obtain anhydrous tungsten oxide W{sub 18}O{sub 49}. Powder X-ray diffraction results confirmed the as prepared WO{sub 3}.H{sub 2}O to be orthorhombic and W{sub 18}O{sub 49} to be monoclinic phase, respectively. Transmission electron micrographs (TEM) revealed that the W{sub 18}O{sub 49} nanosheets have the average dimensions of the order of 250 nm in length and around 150 nm in width. UV-visible diffusion reflectance spectroscopic (DRS) studies revealed the band gap energies to be 3.28 and 3.47 eV for WO{sub 3}.H{sub 2}O and W{sub 18}O{sub 49} samples, respectively. The growth mechanism of two dimensional W{sub 18}O{sub 49} nanosheets is discussed.

Microwave-assisted organic and polymer chemistry

NARCIS (Netherlands)

Hoogenboom, R.; Schubert, U.S.

2009-01-01

The first ACS symposium on Microwave-Assisted Chemistry: Organic and Polymer Synthesis, held as part of the ACS National meeting in Philadelphia, in August 2008, aimed at various topics of the use of microwave irradiation. The symposium found that specific heating effects, such as higher microwave

Microwave heating denitration device

International Nuclear Information System (INIS)

Sato, Hajime; Morisue, Tetsuo.

1984-01-01

Purpose: To suppress energy consumption due to a reflection of microwaves. Constitution: Microwaves are irradiated to the nitrate solution containing nuclear fuel materials, to cause denitrating reaction under heating and obtain oxides of the nuclear fuel materials. A microwave heating and evaporation can for reserving the nitrate solution is disposed slantwise relative to the horizontal plane and a microwave heating device is connected to the evaporation can, and inert gases for agitation are supplied to the solution within the can. Since the evaporation can is slanted, wasteful energy consumption due to the reflection of the microwaves can be suppressed. (Moriyama, K.)

Swelling of spinel after low-dose neutron irradiation

International Nuclear Information System (INIS)

Coghlan, W.A.; Clinard, F.W. Jr.; Itoh, N.; Greenwood, L.R.

1986-01-01

Swelling was determined in samples of single-crystal MgAl 2 O 4 spinel, irradiated to doses as high as 8 x 10 22 n/m 2 (E > 0.1 MeV) at approx. =50 0 C in the Omega West Reactor. Swelling effectively saturated at approx. =2 x 10 22 n/m 2 which corresponds to a damage level of only approx. =2 x 10 -3 dpa. In addition subsequent measurements after irradiation have revealed that the samples continued swelling for several weeks. These results imply that irradiation defects begin to interact by recombination and aggregation at low damage levels in this material at 50 0 C and perhaps continue to cluster at room temperature after irradiation. Rate equations have been employed to determine defect concentrations at saturation. Results to date show that the observed swelling is consistent with the number of surviving defects if swelling per Frenkel defect pair is taken to be one atomic volume

Experimental study on an S-band near-field microwave magnetron power transmission system on hundred-watt level

Science.gov (United States)

Zhang, Biao; Jiang, Wan; Yang, Yang; Yu, Chengyang; Huang, Kama; Liu, Changjun

2015-11-01

A multi-magnetron microwave source, a metamaterial transmitting antenna, and a large power rectenna array are presented to build a near-field 2.45 GHz microwave power transmission system. The square 1 m2 rectenna array consists of sixteen rectennas with 2048 Schottky diodes for large power microwave rectifying. It receives microwave power and converts them into DC power. The design, structure, and measured performance of a unit rectenna as well as the entail rectenna array are presented in detail. The multi-magnetron microwave power source switches between half and full output power levels, i.e. the half-wave and full-wave modes. The transmission antenna is formed by a double-layer metallic hole array, which is applied to combine the output power of each magnetron. The rectenna array DC output power reaches 67.3 W on a 1.2 Ω DC load at a distance of 5.5 m from the transmission antenna. DC output power is affected by the distance, DC load, and the mode of microwave power source. It shows that conventional low power Schottky diodes can be applied to a microwave power transmission system with simple magnetrons to realise large power microwave rectifying.

1,3-Dibromo 5,5-dimethylhydantoin (DBH-Catalyzed Solvent-Free Synthesis of 2-arylbenzimidazoles under Microwave Irradiation

Directory of Open Access Journals (Sweden)

Mehdi Forouzani

2012-01-01

Full Text Available An expeditious synthesis of 2-aryl-benzimidazoles by the condensation of o-phenylenediamine with various arylaldehydes is described. This greener protocol is catalyzed by 1,3-Dibromo 5,5-dimethylhydantoin (DBH, and proceeds efficiently in the absence of any organic solvent under thermal condition and microwave irradiation in high yields.

Biopolymers Regulate Silver Nanoparticle under Microwave Irradiation for Effective Antibacterial and Antibiofilm Activities.

Directory of Open Access Journals (Sweden)

Palaniyandi Velusamy

Full Text Available In the current study, facile synthesis of carboxymethyl cellulose (CMC and sodium alginate capped silver nanoparticles (AgNPs was examined using microwave radiation and aniline as a reducing agent. The biopolymer matrix embedded nanoparticles were synthesized under various experimental conditions using different concentrations of biopolymer (0.5, 1, 1.5, 2%, volumes of reducing agent (50, 100, 150 μL, and duration of heat treatment (30 s to 240 s. The synthesized nanoparticles were analyzed by scanning electron microscopy, UV-Vis spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy for identification of AgNPs synthesis, crystal nature, shape, size, and type of capping action. In addition, the significant antibacterial efficacy and antibiofilm activity of biopolymer capped AgNPs were demonstrated against different bacterial strains, Staphylococcus aureus MTCC 740 and Escherichia coli MTCC 9492. These results confirmed the potential for production of biopolymer capped AgNPs grown under microwave irradiation, which can be used for industrial and biomedical applications.

Role Of SYNBIOTICS And Low Level GAMMA Irradiation Treatments In Improving Performance Of Japanese Quails

International Nuclear Information System (INIS)

ABU-TALEB, A.M.

2009-01-01

A total number of 800 Japanese quail eggs were obtained from a parent flock maintained the poultry research unit of the Biological Application Department, Nuclear Research Centre at Inshas, Egypt, and used in the present study. Before incubating the eggs, they were divided into two equal groups of 400 eggs each; the 1 st group was exposed to a low level of gamma irradiation at 50 rad before sitting while the 2 nd group did not exposed to gamma irradiation. After hatching of the two groups, fertility, hatchability, embryonic mortality and hatching weight were determined. Hatched quail chicks from each group (1 and 2) were divided into four identical subgroups and all fed the basal diet but with a different supplement. The diet of the 1 st subgroup was supplemented with 2.5% Lactobacilli, the 2 nd with 1.5% lactose, the 3 rd with 2.5% Lactobacilli plus 1.5% lactose, while the 4 th subgroup was fed the basal diet only and served as control. The results showed decreased embryonic mortality and increased hatchability and hatching weight due to exposing quail eggs to low level of gamma radiation as compared to non-exposed eggs. The average body weight and the relative weights of carcass, testis and oviduct, egg production, egg weight, serum total protein, albumin, globulins, RBC, WBC and Hb values were increased significantly (P th week due to adding Lactobacilli and lactose to the basal diet. Significant reduction (P<0.05) in the intestinal wall index was observed due to adding Lactobacilli and lactose to the basal diet of hatched quails. In conclusion, adding Lactobacilli and/or lactose to the basal diet of hatched Japanese quails improved performance as well as blood constituents and intestinal wall index. The magnitude of this improvement was even greater when both supplements were combined. In addition, the exposure of eggs to low level of gamma radiation (50 rad) improved hatchability and hatching weight of Japanese quail eggs, but no relationship to dietary

Tradescantia in studies of genetic effects of low level radiation

International Nuclear Information System (INIS)

Yamashita, Atsushi

1976-01-01

Tradescantia in studies on genetic effects of low level radiation is briefly introduced. Radiosensitivity, method of screening stamen hair mutation, materials in current uses, spontaneous mutation rate, and modifying factors are refered. For stamen hair mutation b values in exponential model were lower in irradiation with low dose rate at high environmental temperature. The dose response curves under these modifying conditions, when extrapolated to low dose range, well fit to the line which was obtained by Sparrow's experiment of low level irradiation. In chronic irradiation, the frequency of stamen hair mutation reaches to the constant value after 17 days from the start of irradiation, and is as much as 4 times higher than the peak value in one day irradiation at the same exposure rate. The spontaneous mutation rate of KU-7 varied with temperature. The increase with 1 0 C increment of mean temperature was -0.04%. Uses of Tradescantia in monitoring the environmental radiation is discussed. (auth.)

Kinetic inductance of HTS resonators at various microwave power levels

International Nuclear Information System (INIS)

Srivastava, G.P.; Jacob, Mohan V.

1997-01-01

Microwave superconducting devices show a drastic deterioration in its performance at high microwave power levels. The flux penetration through the weak links increases the quasiparticle concentration which results in the increase of penetration depth and hence the kinetic inductance. We have modeled an expression to find the kinetic inductance at various RF power levels. The results show that the change in kinetic inductance is proportional to be square of the applied field. This model can explain the reported experimental results at and below the intermediate power levels. (author)

Effects of dehulling, steam-cooking and microwave-irradiation on digestive value of white lupin (Lupinus albus) seed meal for rainbow trout (Oncorhynchus mykiss) and Atlantic salmon (Salmo salar).

Science.gov (United States)

Saez, Patricio; Borquez, Aliro; Dantagnan, Patricio; Hernández, Adrián

2015-01-01

A digestibility trial was conducted to assess the effect of dehulling, steam-cooking and microwave-irradiation on the apparent digestibility of nutrients in white lupin (Lupinus albus) seed meal when fed to rainbow trout (Oncorhynchus mykiss) and Atlantic salmon (Salmo salar). Six ingredients, whole lupin seed meal (LSM), dehulled LSM, dehulled LSM steam-cooked for 15 or 45 min (SC15 and SC45, respectively) and LSM microwave-irradiated at 375 or 750 W (MW375 and MW750, respectively), were evaluated for digestibility of dry matter, crude protein (CP), lipids, nitrogen-free extractives (NFE) and gross energy (GE). The diet-substitution approach was used (70% reference diet + 30% test ingredient). Faeces from each tank were collected using a settlement column. Dehulled LSM showed higher levels of proximate components (except for NFE and crude fibre), GE and phosphorus in comparison to whole LSM. Furthermore, SC15, SC45, MW375 and MW750 showed slight variations of chemical composition in comparison to dehulled LSM. Results from the digestibility trial indicated that dehulled LSM, SC15, SC45 and MW375 are suitable processing methods for the improvement of nutrients' apparent digestibility coefficient (ADC) in whole LSM. MW750 showed a lower ADC of nutrients (except for CP and lipids for rainbow trout) in comparison with MW350 for rainbow trout and Atlantic salmon, suggesting a heat damage of the ingredient when microwave-irradiation exceeded 350 W.

The Screening of Genes Sensitive to Long-Term, Low-Level Microwave Exposure and Bioinformatic Analysis of Potential Correlations to Learning and Memory.

Science.gov (United States)

Zhao, Ya Li; Li, Ying Xian; Ma, Hong Bo; Li, Dong; Li, Hai Liang; Jiang, Rui; Kan, Guang Han; Yang, Zhen Zhong; Huang, Zeng Xin

2015-08-01

To gain a better understanding of gene expression changes in the brain following microwave exposure in mice. This study hopes to reveal mechanisms contributing to microwave-induced learning and memory dysfunction. Mice were exposed to whole body 2100 MHz microwaves with specific absorption rates (SARs) of 0.45 W/kg, 1.8 W/kg, and 3.6 W/kg for 1 hour daily for 8 weeks. Differentially expressing genes in the brains were screened using high-density oligonucleotide arrays, with genes showing more significant differences further confirmed by RT-PCR. The gene chip results demonstrated that 41 genes (0.45 W/kg group), 29 genes (1.8 W/kg group), and 219 genes (3.6 W/kg group) were differentially expressed. GO analysis revealed that these differentially expressed genes were primarily involved in metabolic processes, cellular metabolic processes, regulation of biological processes, macromolecular metabolic processes, biosynthetic processes, cellular protein metabolic processes, transport, developmental processes, cellular component organization, etc. KEGG pathway analysis showed that these genes are mainly involved in pathways related to ribosome, Alzheimer's disease, Parkinson's disease, long-term potentiation, Huntington's disease, and Neurotrophin signaling. Construction of a protein interaction network identified several important regulatory genes including synbindin (sbdn), Crystallin (CryaB), PPP1CA, Ywhaq, Psap, Psmb1, Pcbp2, etc., which play important roles in the processes of learning and memorye. Long-term, low-level microwave exposure may inhibit learning and memory by affecting protein and energy metabolic processes and signaling pathways relating to neurological functions or diseases. Copyright © 2015 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.

Preparation of silica nanoparticles through microwave-assisted acid-catalysis.

Science.gov (United States)

Lovingood, Derek D; Owens, Jeffrey R; Seeber, Michael; Kornev, Konstantin G; Luzinov, Igor

2013-12-16

Microwave-assisted synthetic techniques were used to quickly and reproducibly produce silica nanoparticle sols using an acid catalyst with nanoparticle diameters ranging from 30-250 nm by varying the reaction conditions. Through the selection of a microwave compatible solvent, silicic acid precursor, catalyst, and microwave irradiation time, these microwave-assisted methods were capable of overcoming the previously reported shortcomings associated with synthesis of silica nanoparticles using microwave reactors. The siloxane precursor was hydrolyzed using the acid catalyst, HCl. Acetone, a low-tan δ solvent, mediates the condensation reactions and has minimal interaction with the electromagnetic field. Condensation reactions begin when the silicic acid precursor couples with the microwave radiation, leading to silica nanoparticle sol formation. The silica nanoparticles were characterized by dynamic light scattering data and scanning electron microscopy, which show the materials' morphology and size to be dependent on the reaction conditions. Microwave-assisted reactions produce silica nanoparticles with roughened textured surfaces that are atypical for silica sols produced by Stöber's methods, which have smooth surfaces.

Light fluorous-tagged traceless one-pot synthesis of benzimidazoles facilitated by microwave irradiation.

Science.gov (United States)

Tseng, Chih-Chung; Tasi, Cheng-Hsun; Sun, Chung-Ming

2012-06-01

A novel protocol for rapid assemble of benzimidazole framework has been demonstrated. This method incorporated with light fluorous-tag provides a convenient method for diversification of benzimidazoles and for easy purification via fluorous solid-phase extraction (F-SPE) in a parallel manner. The key transformation of this study involves in situ reduction of aromatic nitro compound, amide formation, cyclization and aromatization promoted by microwave irradiation in a one-pot fashion. The strategy is envisaged to be applied for the establishment of drug-like small molecule libraries for high throughput screening.

Microwave-induced torrefaction of rice husk and sugarcane residues

International Nuclear Information System (INIS)

Wang, M.J.; Huang, Y.F.; Chiueh, P.T.; Kuan, W.H.; Lo, S.L.

2012-01-01

This study utilized microwave irradiation to induce torrefaction (mild pyrolysis) of rice husk and sugarcane residues by varying different parameters, including microwave power level, processing time, water content, and particle size of biomass. Proper microwave power levels are suggested to be set between 250 and 300 W for the torrefaction of these two agricultural residues. With proper processing time, the caloric value can increase 26% for rice husk and 57% for sugarcane residue. Compared to dry rice husk, both maximum reaction temperature and mass reduction ratio increased with higher water content (not over 10%). Moreover, the particle size of biomass needs not to be very small. The mass reduction ratios were 65 wt.%, 69 wt.%, and 72 wt.%, when the sizes were 50/100 mesh, 100/200 mesh, and >200 mesh, respectively. Microwave-induced torrefaction reduces more oxygen/carbon ratio of biomass in comparison with traditional torrefaction. Microwave-induced torrefaction is considered as an efficient and promising technology with great potential. -- Highlights: ► Microwave-induced torrefaction is promising compared to conventional methods. ► Neither high microwave power nor small particle size is needed. ► High energy yield can be met under mild microwave power. ► Caloric value can increase up to about 60%.

Low dose irradiation and biological defense mechanisms

International Nuclear Information System (INIS)

Sugahara, Tsutomu; Sagan, L.A.; Aoyama, Takashi

1992-01-01

It has been generally accepted in the context of radiation protection that ionizing radiation has some adverse effect even at low doses. However, epidemiological studies of human populations cannot definitively show its existence or absence. Furthermore, recent studies of populations living in areas of different background radiation levels reported some decrease in adverse health effects at high background levels. Genetic studies of atomic bomb survivors failed to produce statistically significant findings on the mutagenic effects of ionizing radiation. A British study however, suggests that a father's exposure to low dose radiation on the job may increase his children's risk of leukemia. On the other hand, many experimental studies have raised the possibility that low doses of ionizing radiation may not be harmful or may even produce stimulating or adaptive responses. The term 'hormesis' has come to be used to describe these phenomena produced by low doses of ionizing radiation when they were beneficial for the organisms studied. At the end of the International Conference on Low Dose Irradiation one conclusion appeared to be justified: radiation produces an adaptive response, though it is not universally detected yet. The conference failed to obtain any consensus on risk assessment at low doses, but raised many problems to be dealt with by future studies. The editors therefore believe that the Proceedings will be useful for all scientists and people concerned with radiation protection and the biological effects of low-dose irradiation

Single Low-Dose Ionizing Radiation Induces Genotoxicity in Adult Zebrafish and its Non-Irradiated Progeny.

Science.gov (United States)

Lemos, J; Neuparth, T; Trigo, M; Costa, P; Vieira, D; Cunha, L; Ponte, F; Costa, P S; Metello, L F; Carvalho, A P

2017-02-01

This study investigated to what extent a single exposure to low doses of ionizing radiation can induce genotoxic damage in irradiated adult zebrafish (Danio rerio) and its non-irradiated F1 progeny. Four groups of adult zebrafish were irradiated with a single dose of X-rays at 0 (control), 100, 500 and 1000 mGy, respectively, and couples of each group were allowed to reproduce following irradiation. Blood of parental fish and whole-body offspring were analysed by the comet assay for detection of DNA damage. The level of DNA damage in irradiated parental fish increased in a radiation dose-dependent manner at day 1 post-irradiation, but returned to the control level thereafter. The level of DNA damage in the progeny was directly correlated with the parental irradiation dose. Results highlight the genotoxic risk of a single exposure to low-dose ionizing radiation in irradiated individuals and also in its non-irradiated progeny.

The influence of double flask investing on tooth displacement in dentures processed by microwave irradiation.

Science.gov (United States)

Farias Neto, Arcelino; Sousa, Rodrigo L dos Santos; Rizzatti-Barbosa, Célia M

2012-06-01

This study evaluated the influence of the bimaxillary flask (BMF) and two different investing materials on first molar inclination in dentures processed by microwave irradiation. The BMF may minimise tooth displacement, saving time and improving occlusion. Forty pairs of dentures were randomised into four groups: stone wall in monomaxillary flask; silicone wall in BMF; stone wall in BMF; acrylic resin retentions and silicone in BMF. Dentures were processed by microwave irradiation. Two referential points were established on tooth surface. A microscope and a digital pachymeter were used to measure the distance between these points, and the angles α (right maxillary molar), β (left maxillary molar), α' (right mandibular molar) and β' (left mandibular molar) were calculated by the law of cosines. Data were submitted to Kruskal-Wallis (5% significance). No difference was observed among the groups (p > 0.05). In the intra-group analysis, α was significantly different for groups I, II and III; α', for groups II and IV; β, for all groups; β', for groups III and IV. First molar inclination was similar for monomaxillary and BMFs. The use of stone or silicone as investing materials presented the same effect on tooth inclination. © 2011 The Gerodontology Society and John Wiley & Sons A/S.

Radiation-Induced Epigenetic Alterations after Low and High LET Irradiations

Energy Technology Data Exchange (ETDEWEB)

Aypar, Umut; Morgan, William F.; Baulch, Janet E.

2011-02-01

Epigenetics, including DNA methylation and microRNA (miRNA) expression, could be the missing link in understanding the delayed, non-targeted effects of radiation including radiationinduced genomic instability (RIGI). This study tests the hypothesis that irradiation induces epigenetic aberrations, which could eventually lead to RIGI, and that the epigenetic aberrations induced by low linear energy transfer (LET) irradiation are different than those induced by high LET irradiations. GM10115 cells were irradiated with low LET x-rays and high LET iron (Fe) ions and evaluated for DNA damage, cell survival and chromosomal instability. The cells were also evaluated for specific locus methylation of nuclear factor-kappa B (NFκB), tumor suppressor in lung cancer 1 (TSLC1) and cadherin 1 (CDH1) gene promoter regions, long interspersed nuclear element 1 (LINE-1) and Alu repeat element methylation, CpG and non-CpG global methylation and miRNA expression levels. Irradiated cells showed increased micronucleus induction and cell killing immediately following exposure, but were chromosomally stable at delayed times post-irradiation. At this same delayed time, alterations in repeat element and global DNA methylation and miRNA expression were observed. Analyses of DNA methylation predominantly showed hypomethylation, however hypermethylation was also observed. MiRNA shown to be altered in expression level after x-ray irradiation are involved in chromatin remodeling and DNA methylation. Different and higher incidence of epigenetic changes were observed after exposure to low LET x-rays than high LET Fe ions even though Fe ions elicited more chromosomal damage and cell killing. This study also shows that the irradiated cells acquire epigenetic changes even though they are chromosomally stable suggesting that epigenetic aberrations may arise in the cell without initiating RIGI.

Nicotinamide adenosine dinucleotide level in dimethylsulfate-treated or UV-irradiated mouse epidermis

International Nuclear Information System (INIS)

Balard, B.; Giacomoni, P.U.

1989-01-01

The level of nicotinamide (NAD) has been determined in the epidermis of 30 mice. Its value is 0.63+-0.15 μg/mg protein. Upon treatment with dimethylsulfate (DMS), the level of NAD drops in a dosedependent fashion. This diminution is reversible when low doses of DMS are used. Upon irradiation with ultraviolet light, the level of NAD drops in the irradiated epidermis, the treshold of saturation being below 1200 J/m 2 . There is also a drop in the level of NAD in the epidermis protected against irradiation with a black rubber sheet. (author). 17 refs.; 6 figs.; 1 tab

Functionalization of multiwalled carbon nanotubes by microwave irradiation for lysozyme attachment: comparison of covalent and adsorption methods by kinetics of thermal inactivation

Science.gov (United States)

Puentes-Camacho, Daniel; Velázquez, Enrique F.; Rodríguez-Félix, Dora E.; Castillo-Ortega, Mónica; Sotelo-Mundo, Rogerio R.; del Castillo-Castro, Teresa

2017-12-01

Proteins suffer changes in their tertiary structure when they are immobilized, and enzymatic activity is affected due to the low biocompatibility of some supporting materials. In this work immobilization of lysozyme on carbon nanotubes previously functionalized by microwave irradiation was studied. The effectiveness of the microwave-assisted acid treatment of carbon nanotubes was evaluated by XPS, TEM, Raman and FTIR spectroscopy. The carboxylic modification of nanotube surfaces by this fast, simple and feasible method allowed the physical adsorption and covalent linking of active lysozyme onto the carbonaceous material. Thermal inactivation kinetics, thermodynamic parameters and storage stability were studied for adsorbed and covalent enzyme complexes. A major stability was found for lysozyme immobilized by the covalent method, the activation energy for inactivation of the enzyme was higher for the covalent method and it was stable after 50 d of storage at 4 °C. The current study highlights the effect of protein immobilization method on the biotechnological potential of nanostructured biocatalysts.

Evaluation of electron beam irradiation for disinfection of turmeric fingers

Energy Technology Data Exchange (ETDEWEB)

Yasumoto, Kyoden; Fujino, Masayuki; Supriyadi (Kyoto Univ., Uji (Japan). Research Inst. for Food Science); Suzuki, Tetsuya; Hayashi, Toru

1991-08-01

Turmeric finger as one of the most popular spices has been widely used for food manufacturing. However, it has also been a major cause of bacterial infestation of food materials especially in curry, ham and sausage manufacturing. In this study decontamination of bacteria in turmeric finger by electron beam irradiation was evaluated by comparing with several other decontamination methods: i.e., boiling, microwave irradiation, treatment by twin screw extruder and gamma-ray irradiation. By estimation of colony counting on nutrient agar plate, turmeric finger without any treatment gave total viable cell at 10{sup 8}/g. Turmeric finger which was irradiated by electron beam at 10 kGy dose dramatically reduced thermotolerant cell population below self restriction level (<1000/g), which has been required by food hygiene law. The same level of sterilization effect was obtained only by gamma-ray irradiation at 10 kGy and 20 kGy. On the other hand, although treatment through twin screw extruder slightly reduced bacterial numbers, neither boiling nor microwave irradiation gave sufficient decontamination effect on turmeric fingers. (author).

Evaluation of electron beam irradiation for disinfection of turmeric fingers

International Nuclear Information System (INIS)

Yasumoto, Kyoden; Fujino, Masayuki; Supriyadi; Suzuki, Tetsuya; Hayashi, Toru.

1991-01-01

Turmeric finger as one of the most popular spices has been widely used for food manufacturing. However, it has also been a major cause of bacterial infestation of food materials especially in curry, ham and sausage manufacturing. In this study decontamination of bacteria in turmeric finger by electron beam irradiation was evaluated by comparing with several other decontamination methods: i.e., boiling, microwave irradiation, treatment by twin screw extruder and gamma-ray irradiation. By estimation of colony counting on nutrient agar plate, turmeric finger without any treatment gave total viable cell at 10 8 /g. Turmeric finger which was irradiated by electron beam at 10 kGy dose dramatically reduced thermotolerant cell population below self restriction level (<1000/g), which has been required by food hygiene law. The same level of sterilization effect was obtained only by gamma-ray irradiation at 10 kGy and 20 kGy. On the other hand, although treatment through twin screw extruder slightly reduced bacterial numbers, neither boiling nor microwave irradiation gave sufficient decontamination effect on turmeric fingers. (author)

Evaluation of electron beam irradiation for disinfection of turmeric fingers

International Nuclear Information System (INIS)

Yasumoto, K.; Fujino, M.; Supriyadi; Suzuki, T.; Hayashi, T.

1991-01-01

Turmeric finger as one of the most popular spices has been widely used for food manufacturing. However, it has also been a major cause of bacterial infestation of food materials especially in curry, ham and sausage manufacturing. In this study decontamination of bacteria in turmeric finger by electron beam irradiation was evaluated by comparing with several other decontamination methods: i.e., boiling, microwave irradiation, treatment by twin screw extruder and gamma-ray irradiation. By estimation of colony counting on nutrient agar plate, turmeric finger without any treatment gave total viable cell at 10 8 /g. Turmeric finger which was irradiated by electron beam at 10kGy dose dramatically reduced thermotolerant cell population below self restriction level (<1000/g), which has been required by food hygiene law. The same level of sterilization effect was obtained only by gamma-ray irradiation at 10kGy and 20kGy. On the other hand, although treatment through twin screw extruder slightly reduced bacterial numbers, neither boiling nor microwave irradiation gave sufficient decontamination effect on turmeric fingers

Radiation-induced epigenetic alterations after low and high LET irradiations

International Nuclear Information System (INIS)

Aypar, Umut; Morgan, William F.; Baulch, Janet E.

2011-01-01

Epigenetics, including DNA methylation and microRNA (miRNA) expression, could be the missing link in understanding radiation-induced genomic instability (RIGI). This study tests the hypothesis that irradiation induces epigenetic aberrations, which could eventually lead to RIGI, and that the epigenetic aberrations induced by low linear energy transfer (LET) irradiation are different than those induced by high LET irradiations. GM10115 cells were irradiated with low LET X-rays and high LET iron (Fe) ions and evaluated for DNA damage, cell survival and chromosomal instability. The cells were also evaluated for specific locus methylation of nuclear factor-kappa B (NFκB), tumor suppressor in lung cancer 1 (TSLC1) and cadherin 1 (CDH1) gene promoter regions, long interspersed nuclear element 1 (LINE-1) and Alu repeat element methylation, CpG and non-CpG global methylation and miRNA expression levels. Irradiated cells showed increased micronucleus induction and cell killing immediately following exposure, but were chromosomally stable at delayed times post-irradiation. At this same delayed time, alterations in repeat element and global DNA methylation and miRNA expression were observed. Analyses of DNA methylation predominantly showed hypomethylation, however hypermethylation was also observed. We demonstrate that miRNA expression levels can be altered after X-ray irradiation and that these miRNA are involved in chromatin remodeling and DNA methylation. A higher incidence of epigenetic changes was observed after exposure to X-rays than Fe ions even though Fe ions elicited more chromosomal damage and cell killing. This distinction is apparent at miRNA analyses at which only three miRNA involved in two major pathways were altered after high LET irradiations while six miRNA involved in five major pathways were altered after low LET irradiations. This study also shows that the irradiated cells acquire epigenetic changes suggesting that epigenetic aberrations may arise in the

Radiation-induced epigenetic alterations after low and high LET irradiations

Energy Technology Data Exchange (ETDEWEB)

Aypar, Umut, E-mail: uaypa001@umaryland.edu [Department of Radiation Oncology, Radiation Oncology Research Laboratory, University of Maryland School of Medicine, Baltimore, MD 21201 (United States); Morgan, William F. [Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Baulch, Janet E. [Department of Radiation Oncology, Radiation Oncology Research Laboratory, University of Maryland School of Medicine, Baltimore, MD 21201 (United States)

2011-02-10

Epigenetics, including DNA methylation and microRNA (miRNA) expression, could be the missing link in understanding radiation-induced genomic instability (RIGI). This study tests the hypothesis that irradiation induces epigenetic aberrations, which could eventually lead to RIGI, and that the epigenetic aberrations induced by low linear energy transfer (LET) irradiation are different than those induced by high LET irradiations. GM10115 cells were irradiated with low LET X-rays and high LET iron (Fe) ions and evaluated for DNA damage, cell survival and chromosomal instability. The cells were also evaluated for specific locus methylation of nuclear factor-kappa B (NF{kappa}B), tumor suppressor in lung cancer 1 (TSLC1) and cadherin 1 (CDH1) gene promoter regions, long interspersed nuclear element 1 (LINE-1) and Alu repeat element methylation, CpG and non-CpG global methylation and miRNA expression levels. Irradiated cells showed increased micronucleus induction and cell killing immediately following exposure, but were chromosomally stable at delayed times post-irradiation. At this same delayed time, alterations in repeat element and global DNA methylation and miRNA expression were observed. Analyses of DNA methylation predominantly showed hypomethylation, however hypermethylation was also observed. We demonstrate that miRNA expression levels can be altered after X-ray irradiation and that these miRNA are involved in chromatin remodeling and DNA methylation. A higher incidence of epigenetic changes was observed after exposure to X-rays than Fe ions even though Fe ions elicited more chromosomal damage and cell killing. This distinction is apparent at miRNA analyses at which only three miRNA involved in two major pathways were altered after high LET irradiations while six miRNA involved in five major pathways were altered after low LET irradiations. This study also shows that the irradiated cells acquire epigenetic changes suggesting that epigenetic aberrations may arise

Microwave energy for post-calcination treatment of high-level nuclear wastes

International Nuclear Information System (INIS)

Gombert, D.; Priebe, S.J.; Berreth, J.R.

1980-01-01

High-level radioactive wastes generated from nuclear fuel reprocessing require treatment for effective long-term storage. Heating by microwave energy is explored in processing of two possible waste forms: (1) drying of a pelleted form of calcined waste; and (2) vitrification of calcined waste. It is shown that residence times for these processes can be greatly reduced when using microwave energy rather than conventional heating sources, without affecting product properties. Compounds in the waste and in the glass frit additives couple very well with the 2.45 GHz microwave field so that no special microwave absorbers are necessary

assessment Of the effect Of low Level Laser Therapy on Parotid glands of gamma Irradiated Rats

International Nuclear Information System (INIS)

Ahmed, S.F.

2013-01-01

Gamma radiation-induced salivary gland dysfunction has a major deleterious effect on oral health. Aim: This study was carried out to evaluate the possible effect of low level laser therapy (LLLT) on radiation induced oxidative stress in rats’ salivary glands. Material and Methods: Sixty four male Albino rats were divided into two groups. One group where the left parotid gland was exposed to 3 sessions of LLL, then rats were subjected to 3 sessions of whole body gamma-radiation. In the other group, rats were subjected to 3 sessions of gamma-radiation; each was followed by a session of LLL to the left parotid gland. The right gland of both groups was used as irradiated control. Parotid glands were collected 1 day, 3 days, 1 week and 2 weeks after the end of treatment and were subjected to histological examination and immunohistochemical analysis. Results: The parotid gland of both laser groups showed less intra cytoplasmic vacuolisation, slight alteration of acinar architecture and almost even size nuclei as compared to the irradiated gland. LLL either before or parallel to gamma-irradiation was effective in increasing cell proliferation on the third and seventh day, respectively as compared to the gamma irradiated group (P<0.05). Statistically, results revealed significant decrease in optical density of caspase 3 activity in the lased groups on the first week as compared to the control. Conclusion: LLLT attenuates the harmful effect of gamma irradiation on the parotid glands of the rats. Also, it improves gland regeneration through modulation of cell proliferation and apoptosis inflammation

Influence on living body by radiant rays produced in low power reactor. Irradiation of rabbit inside of low power reactor (UTR-KINKI)

Energy Technology Data Exchange (ETDEWEB)

Ogura, Isao; Nakamura, Katsuichi; Usuyama, Hideo; Usui, Akinori; Hosomi, Takashi; Yoshimura, Yoshinao; Nakai, Takahide; Egashira, Masamichi

1984-12-01

There is possibility of a risk that a living body is irradiated by those for slightly indifference to radiant rays, radiation source or devices of low level dose or dose rate. Accordingly, a low power reactor (UTR-KINKI) was utilized for a observation of influence by radiation of low level dose or dose rate, the rabbits were irradiated in it at output 1 w. The large influence was not expected for the low level dose rate of 1.313 Rad/hr even if they were irradiated for the several hours, but in a part of blood components a slight change was recognized. The change of M pattern in white blood corpuscle number was indicated likewise as irradiation of 500R X-ray, reported from Jacobson and others, by irradiation to about 13 Rads. In addition, lymphocyte number was increased considerably in an early stage. This fact will be useful for a recovery of an injury as mentioned by Lucky. The rabbits of alloxan diabetes mellitus and hepatitis were irradiated in the same way as above, but they scarcely showed the alterations. However, numerous rabbits can't be used in this experiment for the equipment and others. (author).

Extreme ultraviolet spectroscopy of low pressure helium microwave driven discharges

Science.gov (United States)

Espinho, Susana; Felizardo, Edgar; Tatarova, Elena; Alves, Luis Lemos

2016-09-01

Surface wave driven discharges are reliable plasma sources that can produce high levels of vacuum and extreme ultraviolet radiation (VUV and EUV). The richness of the emission spectrum makes this type of discharge a possible alternative source in EUV/VUV radiation assisted applications. However, due to challenging experimental requirements, publications concerning EUV radiation emitted by microwave plasmas are scarce and a deeper understanding of the main mechanisms governing the emission of radiation in this spectral range is required. To this end, the EUV radiation emitted by helium microwave driven plasmas operating at 2.45 GHz has been studied for low pressure conditions. Spectral lines from excited helium atoms and ions were detected via emission spectroscopy in the EUV/VUV regions. Novel data concerning the spectral lines observed in the 23 - 33 nm wavelength range and their intensity behaviour with variation of the discharge operational conditions are presented. The intensity of all the spectral emissions strongly increases with the microwave power delivered to the plasma up to 400 W. Furthermore, the intensity of all the ion spectral emissions in the EUV range decreases by nearly one order of magnitude as the pressure was raised from 0.2 to 0.5 mbar. Work funded by FCT - Fundacao para a Ciencia e a Tecnologia, under Project UID/FIS/50010/2013 and grant SFRH/BD/52412/2013 (PD-F APPLAuSE).

Serum protein concentration in low-dose total body irradiation of normal and malnourished rats

International Nuclear Information System (INIS)

Viana, W.C.M.; Lambertz, D.; Borges, E.S.; Neto, A.M.O.; Lambertz, K.M.F.T.; Amaral, A.

2016-01-01

Among the radiotherapeutics' modalities, total body irradiation (TBI) is used as treatment for certain hematological, oncological and immunological diseases. The aim of this study was to evaluate the long-term effects of low-dose TBI on plasma concentration of total protein and albumin using prematurely and undernourished rats as animal model. For this, four groups with 9 animals each were formed: Normal nourished (N); Malnourished (M); Irradiated Normal nourished (IN); Irradiated Malnourished (IM). At the age of 28 days, rats of the IN and IM groups underwent total body gamma irradiation with a source of cobalt-60. Total protein and Albumin in the blood serum was quantified by colorimetry. This research indicates that procedures involving low-dose total body irradiation in children have repercussions in the reduction in body-mass as well as in the plasma levels of total protein and albumin. Our findings reinforce the periodic monitoring of total serum protein and albumin levels as an important tool in long-term follow-up of pediatric patients in treatments associated to total body irradiation. - Highlights: • Low-dose total body irradiation (TBI) in children have repercussions in their body-mass. • Long-term total protein and albumin levels are affected by TBI. • The monitoring of total protein and albumin levels are useful in the follow-up of TBI pediatric patients.

Low-temperature preparation and microwave photocatalytic activity study of TiO2-mounted activated carbon

International Nuclear Information System (INIS)

Liu Yazi; Yang Shaogui; Hong Jun; Sun Cheng

2007-01-01

TiO 2 thin films were deposited on granular activated carbon by a dip-coating method at low temperature (373 K), using microwave radiation to enhance the crystallization of titania nanoparticles. Uniform and continuous anatase titania films were deposited on the surface of activated carbon. BET surface area of TiO 2 -mounted activated carbon (TiO 2 /AC) decreased a little in comparison with activated carbon. TiO 2 /AC possessed strong optical absorption capacity with a band gap absorption edge around 360 nm. The photocatalytic activity did not increase when the as-synthesized TiO 2 /AC was thermally treated, but was much higher than commercial P-25 in degradation of phenol by irradiation of electrodeless discharge lamps (EDLs)

Biosythesis of Silver Nanoparticles using Putri Malu (Mimosa pudica Leaves Extract and Microwave Irradiation Method

Directory of Open Access Journals (Sweden)

Is Fatimah

2016-11-01

Full Text Available In this paper, the biosynthesis of silver nanoparticles (AgNPs using Mimosa pudica extract is discussed. Mimosa pudica leaves extract using water as solvent was used as bio-reductor to an aqueous solution of silver nitrate (AgNO3 and in order to accelerate the reduction, microwave irradiation method was applied. The AgNPs obtained were characterized using UV-Vis spectrophotometry, FTIR spectrophotometry, XRD, SEM-EDX, and particle size analysis based on dynamic scattering method. Effect of preparation method to the formation of AgNPs is also evaluated in antibacterial activity towards E.coli and P. aeruginosa. Rapid and ecofriendly biosynthesis of stable silver nanoparticles was observed in this study. The characterization results and antibacterial assay indicated the uniform and smaller particle size of AgNPs obtained by using microwave method and positively enhance the antibacterial activity against tested bacteria.

Microwave-assisted extraction of pectin from cocoa peel

Science.gov (United States)

Sarah, M.; Hanum, F.; Rizky, M.; Hisham, M. F.

2018-02-01

Pectin is a polymer of d-galacturonate acids linked by β-1,4 glycosidic bond. This study isolates pectin from cocoa peel (Theobroma cacao) using citric acid as solvent by microwave-assisted extraction method. Cocoa peels (moisture content of 10%) with citric acid solution (pH of 1.5) irradiated by microwave energy at various microwave power (180, 300, 450 and 600 W) for 10, 15, 20, 25 and 30 minutes respectively. Pectin obtained from this study was collected and filtrated by adding 96% ethanol to precipitate the pectin. The best results obtained from extraction process using microwave power of 180 Watt for 30 minutes. This combination of power and time yielded 42.3% pectin with moisture content, ash content, weight equivalent, methoxyl content and galacturonate levels were 8.08%, 5%, 833.33 mg, 6.51% and 58,08%, respectively. The result finding suggested that microwave-assisted extraction method has a great potency on the commercial pectin production.

Effects of low-dose rate irradiation on two types of type II diabetes model mice

International Nuclear Information System (INIS)

Nomura, Takaji; Sakai, Kazuo

2004-01-01

The effects of low-dose rate gamma-irradiation were investigated in two mouse strains - C57BL/KsJ-db/db (db mouse) and AKITA (AKITA mouse)-for type II diabetes mellitus. Both strains develop the developed type II diabetes by about 8 weeks of age due to dysfunction of the insulin/insulin receptor. The db Mouse' shows obese and exhibits hyperinsulinism, and the onset of Type II diabetes like resembles that for Westerners. On the other hand, the AKITA mouse has exhibits disordered insulin secretion, and the diabetes such as resembles that of Asians. Ten-week old female mice, in groups of 8 or 12, were irradiated at 0.65 mGy/hr in the low-dose rate irradiation facility in the Low Dose Radiation Research Center. The level of urine glucose was measured with test slips. The urine glucose levels of all of the mice were highly elevated the beginning of the irradiation. In the irradiated group of db mice, three mice showed decrease in glucose level compare to the level of non-irradiated diabetes mice after 35, 52 or 80 weeks of irradiation. All had maintained a normal level thereafter. No such improvement in diabetes was ever observed in the 12 mice of in the non-irradiated control group. The AKITA mice, however, did not decrease the glucose level regardless of the irradiation. Both the db mice and AKITA mice had their lives prolonged their life by the irradiation. The survival rate of db mice at the age of 90 weeks was 75% in the irradiated group, but 50% in the non-irradiated group. The average life span was 104 weeks in the irradiated group and 87 weeks in the control group. Furthermore, a marked difference was furthermore observed in the appearance of the coat hair, skin, and tail; appearances were well preserved in the irradiated group. The average life span in the irradiated AKITA mice was also longer than that for the non-irradiated mice, 51 weeks and 41 weeks in the irradiated and non-irradiated group respectively. These results suggest that the low-dose irradiation

Melanin is Effective Radioprotector against Chronic Irradiation and Low Radiation Doses

International Nuclear Information System (INIS)

Mosse, I.; Plotnikova, S.; Kostrova, L.; Molophei, V.; Dubovic, B.

2001-01-01

Full text: Earlier we found pigment melanin ability to reduce significantly genetic consequences of acute irradiation in animals (drosophila, mice) and cultured human cells and to decrease strongly 'genetic load' accumulated in irradiated populations. The influence of melanin isolated from human hair on genetic effects of chronic irradiation in mice has been investigated. Melanin suspension or distilled water were injected every day into stomach of animals during 1-3 Gy g-irradiation with dose rate 0.007Gy/h. Levels of reciprocal translocations in germ cells were analysed cytologically. Melanin influence on genetic effect of chronic irradiation was shown to be even more effective than that of acute one. Radioadaptive response was used in order to study melanin influence on low radiation dose effect. We have demonstrated adaptive response in mice germ cells and bone marrow cells frequency of chromosomal aberrations in these cells after 0.2+1.5 Gy was about half as much as 1.7 Gy effect. Melanin injection 2 hours before the conditioning dose of 0.2 Gy resulted in the same mutation level as before 1.7 Gy adaptive response was not found. If melanin was applied between the first and second doses, both adaptive reaction and protection led to 4-fold decrease in aberration level. Thus melanin is able to remove completely low radiation dose effect. Complete toxicological tests have been conducted. The pigment melanin is not toxic and does not possess a mutagenic, teratogenic or carcinogenic activity. Melanin could be used in medicine for people protection against genetic consequences of long-term irradiation at low doses. (author)

Erbium trifluoromethanesulfonate-catalyzed Friedel–Crafts acylation using aromatic carboxylic acids as acylating agents under monomode-microwave irradiation

DEFF Research Database (Denmark)

Tran, Phuong Hoang; Hansen, Poul Erik; Nguyen, Hai Truong

2015-01-01

Erbium trifluoromethanesulfonate is found to be a good catalyst for the Friedel–Crafts acylation of arenes containing electron-donating substituents using aromatic carboxylic acids as the acylating agents under microwave irradiation. An effective, rapid and waste-free method allows the preparation...... of a wide range of aryl ketones in good yields and in short reaction times with minimum amounts of waste...

Influence of continuous microwave irradiation of low intensity on the behaviour of albino rats

International Nuclear Information System (INIS)

Rynskov, V.V.

1985-01-01

A study was made of a single 10 min exposure of albino rats to microwaves (6 GHz, 0.2 MW/cm 2 ) on their orientative-trying reaction. The locomotive activity, attentiveness and trying activity of the experimental animals were found to increase

Study of federal microwave standards

Energy Technology Data Exchange (ETDEWEB)

David, L.

1980-08-01

Present and future federal regulatory processes which may impact the permissible levels of microwave radiation emitted by the SPS Microwave Power Transmission (MPTS) were studied. An historical development of US occupational and public microwave standards includes an overview of Western and East European philosophies of environmental protection and neurophysiology which have led to the current widely differing maximum permissible exposure limits to microwaves. The possible convergence of microwave standards is characterized by a lowering of Western exposure levels while Eastern countries consider standard relaxation. A trend toward stricter controls on activities perceived as harmful to public health is under way as is interest in improving the federal regulatory process. Particularly relevant to SPS is the initiation of long-term, low-level microwave exposure programs. Coupled with new developments in instrumentation and dosimetry, the results from chronic exposure program and population exposure studies could be expected within the next five to ten years. Also discussed is the increasing public concern that rf energy is yet another hazardous environmental agent.

Synergistic pretreatment of waste activated sludge using CaO_2 in combination with microwave irradiation to enhance methane production during anaerobic digestion

International Nuclear Information System (INIS)

Wang, Jie; Li, Yongmei

2016-01-01

Highlights: • CaO_2/MW pretreatment synergistically enhanced WAS solubilization and CH_4 production. • MW irradiation facilitated more "·OH generation from CaO_2. • The optimal pretreatment condition for methane production was determined. • The growths of both hydrogenotrophic and acetate-utilizing methanogens were promoted. • The dewaterability of WAS was improved considerably by CaO_2/MW treatment. - Abstract: To investigate the effects of combined calcium peroxide (CaO_2) and microwave pretreatment on anaerobic digestion of waste activated sludge, lab-scale experiments were conducted to measure the solubilization, biodegradation, and dewaterability of the waste activated sludge. Additionally, the synergistic effects between CaO_2 and microwave were studied, and the microbial activity and methanogenic archaea community structure were analyzed. Combined pretreatment considerably facilitated the solubilization and subsequent anaerobic digestion of the waste activated sludge. The optimal pretreatment condition was CaO_2 (0.1 g/gVSS)/microwave (480 W, 2 min) for methane production during the subsequent anaerobic digestion process. Under this condition, 80.2% higher CH_4 accumulation yield was achieved after 16 d of anaerobic digestion when compared with the control. The synergistic effects of CaO_2/microwave pretreatment resulted from the different mechanisms of CaO_2 and microwave treatments. Further, microwave irradiation increased "·OH generation from CaO_2 and significantly alleviated the inhibitory effect of CaO_2 on methanogens. The activities of hydrolytic enzymes and acid-forming enzymes in the waste activated sludge were improved after CaO_2 (0.1 g/gVSS)/microwave (480 W, 2 min) pretreatment. Methanogenesis enzyme activity was also higher after CaO_2 treatment (0.1 g/gVSS)/microwave (480 W, 2 min) following a lag period. Illumina MiSeq sequencing analysis indicated that acetate-utilizing methanogen (Methanosaeta sp.) and H_2/CO_2-utilizing

The wholesomeness of irradiated food

International Nuclear Information System (INIS)

Elias, P.S.

1976-01-01

The acceptance of food irradiation as a safe process of preservation by national authorities concerned with the safety of foodstuffs has hitherto made slow progress. The technology has existed for some 25 years but the general attitude towards official acceptance of the process has been marred by irrational and unscientific fears. As may have been mentioned by previous speakers,'the basic process of food irradiation does not differ in the physical sense from any other food processing techniques which involve the application of radiation energy to food. The energy level used in food irradiation is too low ever to lead to any production of radioactivity in the irradiated food, hence wholesomeness considerations can totally exclude this aspect. The uniqueness of food irradiation rests inherently on the particular type of energy employed and has aroused special attention because of this fact. The wholesomeness of food treated by heat or microwaves has not been questioned to the same extent, yet the very same question has been raised in relation to treatment by gamma rays and electron beams. Being a new process it requires not only a toxicological but also a microbiological as well as nutritional approach to the assessment of the wholesomeness of irradiated food. Studies on the radiation chemistry of proteins, lipids and carbohydrates, the main constituents of foods, when irradiated in the Mrad range, have yielded information which shows that these substances react in a reasonably uniform manner to irradiation. Many of the irradiation-induced compounds identified in irradiated foods can also be found in various non-irradiated foods. For those products that have been identified, the quantities found are in the parts per million range or less. Available data on the structures of radiation chemical products in food and the very low concentrations at which they occur, suggest the general conclusion that the health hazard they might represent is negligible

The effects of low level laser irradiation on proliferation of human dental pulp: a narrative review.

Science.gov (United States)

Staffoli, S; Romeo, U; Amorim, R N S; Migliau, G; Palaia, G; Resende, L; Polimeni, A

2017-01-01

Mesenchymal stem cells (MSCs) have the capability for self-renewal, proliferation, and differentiation in various types of specialized cells, so they are very important in cellular therapies. MSC from dental pulp are simply obtainable and have high proliferative capability. Among the therapies that can stimulate the proliferation of certain cell types, low-level laser therapy (LLLT) stands out. The target of this study is to perform a literature review to investigate these effects of low-level laser irradiation on proliferation of human dental pulp.The electronic search of scientific papers was conducted in the Lilacs, Scielo, Medline and PubMed databases through scientific articles published in national and international journals in the past 20 years.The results of this review suggest that LLLT may be a useful and important tool for future advances in cell therapy and tissue engineering associated to stem cells. Studies on cell therapy for regenerating dental tissues has already been done, and shows promising results.

Investigation of Rapid Low-Power Microwave-Induction Heating Scheme on the Cross-Linking Process of the Poly(4-vinylphenol) for the Gate Insulator of Pentacene-Based Thin-Film Transistors

Science.gov (United States)

Fan, Ching-Lin; Shang, Ming-Chi; Wang, Shea-Jue; Hsia, Mao-Yuan; Lee, Win-Der; Huang, Bohr-Ran

2017-01-01

In this study, a proposed Microwave-Induction Heating (MIH) scheme has been systematically studied to acquire suitable MIH parameters including chamber pressure, microwave power and heating time. The proposed MIH means that the thin indium tin oxide (ITO) metal below the Poly(4-vinylphenol) (PVP) film is heated rapidly by microwave irradiation and the heated ITO metal gate can heat the PVP gate insulator, resulting in PVP cross-linking. It is found that the attenuation of the microwave energy decreases with the decreasing chamber pressure. The optimal conditions are a power of 50 W, a heating time of 5 min, and a chamber pressure of 20 mTorr. When suitable MIH parameters were used, the effect of PVP cross-linking and the device performance were similar to those obtained using traditional oven heating, even though the cross-linking time was significantly decreased from 1 h to 5 min. Besides the gate leakage current, the interface trap state density (Nit) was also calculated to describe the interface status between the gate insulator and the active layer. The lowest interface trap state density can be found in the device with the PVP gate insulator cross-linked by using the optimal MIH condition. Therefore, it is believed that the MIH scheme is a good candidate to cross-link the PVP gate insulator for organic thin-film transistor applications as a result of its features of rapid heating (5 min) and low-power microwave-irradiation (50 W). PMID:28773101

Investigation of Rapid Low-Power Microwave-Induction Heating Scheme on the Cross-Linking Process of the Poly(4-vinylphenol for the Gate Insulator of Pentacene-Based Thin-Film Transistors

Directory of Open Access Journals (Sweden)

Ching-Lin Fan

2017-07-01

Full Text Available In this study, a proposed Microwave-Induction Heating (MIH scheme has been systematically studied to acquire suitable MIH parameters including chamber pressure, microwave power and heating time. The proposed MIH means that the thin indium tin oxide (ITO metal below the Poly(4-vinylphenol (PVP film is heated rapidly by microwave irradiation and the heated ITO metal gate can heat the PVP gate insulator, resulting in PVP cross-linking. It is found that the attenuation of the microwave energy decreases with the decreasing chamber pressure. The optimal conditions are a power of 50 W, a heating time of 5 min, and a chamber pressure of 20 mTorr. When suitable MIH parameters were used, the effect of PVP cross-linking and the device performance were similar to those obtained using traditional oven heating, even though the cross-linking time was significantly decreased from 1 h to 5 min. Besides the gate leakage current, the interface trap state density (Nit was also calculated to describe the interface status between the gate insulator and the active layer. The lowest interface trap state density can be found in the device with the PVP gate insulator cross-linked by using the optimal MIH condition. Therefore, it is believed that the MIH scheme is a good candidate to cross-link the PVP gate insulator for organic thin-film transistor applications as a result of its features of rapid heating (5 min and low-power microwave-irradiation (50 W.

Microwave-Induced Chemotoxicity of Polydopamine-Coated Magnetic Nanocubes

KAUST Repository

Julfakyan, Khachatur

2015-08-06

Polydopamine-coated FeCo nanocubes (PDFCs) were successfully synthesized and tested under microwave irradiation of 2.45 GHz frequency and 0.86 W/cm2 power. These particles were found to be non-toxic in the absence of irradiation, but gained significant toxicity upon irradiation. Interestingly, no increase in relative heating rate was observed when the PDFCs were irradiated in solution, eliminating nanoparticle (NP)-induced thermal ablation as the source of toxicity. Based on these studies, we propose that microwave-induced redox processes generate the observed toxicity. © 2015 by the authors; licensee MDPI, Basel, Switzerland.

Low cost heterogenous catalyst from (Achatina Fulica) snail shell and its application for biodiesel conversion via microwave irradiation

Science.gov (United States)

Fatimah, Is; Kurniastuti, E. A.; Basthiani, I. A.; Fakhri, A.

2017-11-01

Research on preparation of heterogenous catalyst from Achatina Fulica snail shell and its application biodiesel conversion has been investigation. Research aimed to obtain low cost and reusable catalyst for biodiesel production. The catalyst was prepared by grinding and calcining the snail shell at 900°C for 2 hours. The obtained solid was analysed by using XRD, SEM-EDX. FTIR, and also basicity measurement. Catalyst was used in the cenvertion of rice bran oil transesterification at varied volume of oil methanol ratio of 20-80 under microwave and reflux methode. The transesterification result were analyzed by using GCMS.

Effect of modified graphene and microwave irradiation on the mechanical and thermal properties of poly(styrene-co-methyl methacrylate)/graphene nanocomposites

KAUST Repository

Zubair, Mukarram; Jose, Jobin Vinodh; Emwas, Abdul-Hamid M.; Al-Harthi, Mamdouh Ahmed

2014-01-01

The effect of modified graphene (MG) and microwave irradiation on the interaction between graphene (G) and poly(styrene-co-methyl meth acrylate) [P(S-co-MMA)] polymer matrix has been studied in this article. Modification of graphene was performed

Microwave thermal remediation of crude oil contaminated soil enhanced by carbon fiber.

Science.gov (United States)

Li, Dawei; Zhang, Yaobin; Quan, Xie; Zhao, Yazhi

2009-01-01

Thermal remediation of the soil contaminated with crude oil using microwave heating enhanced by carbon fiber (CF) was explored. The contaminated soil was treated with 2.45 GHz microwave, and CF was added to improve the conversion of microwave energy into thermal energy to heat the soil. During microwave heating, the oil contaminant was removed from the soil matrix and recovered by a condensation system of ice-salt bath. The experimental results indicated that CF could efficiently enhance the microwave heating of soil even with relatively low-dose. With 0.1 wt.% CF, the soil could be heated to approximately 700 degrees C within 4 min using 800 W of microwave irradiation. Correspondingly, the contaminated soil could be highly cleaned up in a short time. Investigation of oil recovery showed that, during the remediation process, oil contaminant in the soil could be efficiently recovered without causing significant secondary pollution.

Ameliorative effects of low dose/low dose-rate irradiation on reactive oxygen species-related diseases model mice

International Nuclear Information System (INIS)

Nomura, Takaharu

2008-01-01

Living organisms have developed complex biological system which protects themselves against environmental radiation, and irradiation with proper dose, dose-rate and irradiation time can stimulate their biological responses against oxidative stress evoked by the irradiation. Because reactive oxygen species are involved in various human diseases, non-toxic low dose/low dose-rate radiation can be utilized for the amelioration of such diseases. In this study, we used mouse experimental models for fatty liver, nephritis, diabetes, and ageing to elucidate the ameliorative effect of low dose/low dose-rate radiation in relation to endogenous antioxidant activity. Single irradiation at 0.5 Gy ameliorates carbon tetrachloride-induced fatty liver. The irradiation increases hepatic anti-oxidative system involving glutathione and glutathione peroxidase, suggesting that endogenous radical scavenger is essential for the ameliorative effect of low dose radiation on carbon tetrachloride-induced fatty liver. Single irradiation at 0.5 Gy ameliorates ferric nitrilotriacetate-induced nephritis. The irradiation increases catalase and decreases superoxide dismutase in kidney. The result suggests that low dose radiation reduced generation of hydroxide radical generation by reducing cellular hydroperoxide level. Single irradiation at 0.5 Gy at 12 week of age ameliorates incidence of type I diabetes in non-obese diabetic (NOD) mice through the suppression of inflammatory activity of splenocytes, and resultant apoptosis of β-cells in pancreas. The irradiation activities of superoxide dismutase and catalase, which coordinately diminish intracellular reactive oxygen species. Continuous irradiation at 0.70 mGy/hr from 10 week of age elongates life span, and suppresses alopecia in type II diabetesmice. The irradiation improved glucose clearance without affecting insulin-resistance, and increased pancreatic catalase activity. The results suggest that continuous low dose-rate irradiation protect

Effect of low-level laser irradiation on osteoblast-like cells cultured on porous hydroxyapatite scaffolds

Directory of Open Access Journals (Sweden)

Serena Incerti Parenti

2013-09-01

Full Text Available OBJECTIVE: To determine the effect of laser irradiation at a low dose on human osteoblastlike cells. Materials and methods: 32 porous hydroxyapatite scaffolds currently used for bone tissue engineering were seeded with MG63 cells and irradiated or not with a GaAlAs diode laser (wavelength 915 nm, dose 2 J/cm² using different power density and exposure duration. RESULTS: After 72-h incubation, cells showed well spread morphology and good adhesion on both laser-treated and untreated scaffolds. Laser irradiation did not interfere in cell viability and proliferation as compared with the non-irradiated controls. CONCLUSION: This study suggests that there is no effect of 915 nm laser irradiation at a dose of 2 J/cm² on the proliferation rate of MG63 cells. Future investigations are needed to compare different dose and wavelength regimens in order to determine the optimal set of laser parameters for maximum cell yield and safe clinical application.

Studies concerning the effects of low level prenatal X-irradiation on postnatal growth and adult behaviour in the Wistar rat

International Nuclear Information System (INIS)

Jensh, R.P.; Brent, R.L.; Vogel, W.H.

1986-01-01

Fifty-nine pregnant Wistar strain rats were sham irradiated or given a 0.1 or 0.2 Gy exposure of X-radiation on the 9th or 17th day of gestation. Twenty-seven were killed at term for teratologic analysis. The remaining mothers raised their young. At 60 days of age the 252 offspring were randomly assigned three of six tests: open field, swimming, hanging, activity wheel, water T-maze, or conditioned avoidance response. Male offspring exposed at the 0.2 Gy level exhibited retarded growth only during the first few weeks of postnatal life. Female offspring exposed on the 17th day to 0.2 Gy X-radiation were growth retarded throughout the test period. Postnatal growth rates were not significantly different between the irradiated and control groups. There were no significant alterations in adult behaviour due to prenatal X-irradiation. There were sex differences in activity wheel and forelimb hanging performance, unrelated to radiation exposure. These results indicate that prenatal low level X-irradiation on the 9th or 17th day of gestation dose not result in significant alterations in rat adult behavioural performance but prenatal growth retardation persists postnatally. Growth may be a more sensitive indicator of the effects of prenatal exposure than postnatal behaviour. (author)

Fast surface modification by microwave assisted click reactions on silicon substrates

NARCIS (Netherlands)

Haensch, C.; Erdmenger, T.; Fijten, M.W.M.; Höppener, S.; Schubert, U.S.

2009-01-01

Microwave irradiation has been used for the chemical modification of functional monolayers on silicon surfaces. The thermal and chemical stability of these layers was tested under microwave irradiation to investigate the possibility to use this alternative heating process for the surface

Low intensity microwave radiation induced oxidative stress, inflammatory response and DNA damage in rat brain.

Science.gov (United States)

Megha, Kanu; Deshmukh, Pravin Suryakantrao; Banerjee, Basu Dev; Tripathi, Ashok Kumar; Ahmed, Rafat; Abegaonkar, Mahesh Pandurang

2015-12-01

Over the past decade people have been constantly exposed to microwave radiation mainly from wireless communication devices used in day to day life. Therefore, the concerns over potential adverse effects of microwave radiation on human health are increasing. Until now no study has been proposed to investigate the underlying causes of genotoxic effects induced by low intensity microwave exposure. Thus, the present study was undertaken to determine the influence of low intensity microwave radiation on oxidative stress, inflammatory response and DNA damage in rat brain. The study was carried out on 24 male Fischer 344 rats, randomly divided into four groups (n=6 in each group): group I consisted of sham exposed (control) rats, group II-IV consisted of rats exposed to microwave radiation at frequencies 900, 1800 and 2450 MHz, specific absorption rates (SARs) 0.59, 0.58 and 0.66 mW/kg, respectively in gigahertz transverse electromagnetic (GTEM) cell for 60 days (2h/day, 5 days/week). Rats were sacrificed and decapitated to isolate hippocampus at the end of the exposure duration. Low intensity microwave exposure resulted in a frequency dependent significant increase in oxidative stress markers viz. malondialdehyde (MDA), protein carbonyl (PCO) and catalase (CAT) in microwave exposed groups in comparison to sham exposed group (pmicrowave exposed groups (pmicrowave exposed animal (pmicrowave exposed groups as compared to their corresponding values in sham exposed group (pmicrowave radiation induces oxidative stress, inflammatory response and DNA damage in brain by exerting a frequency dependent effect. The study also indicates that increased oxidative stress and inflammatory response might be the factors involved in DNA damage following low intensity microwave exposure. Copyright © 2015 Elsevier Inc. All rights reserved.

Acetic acid-promoted condensation of o-phenylenediamine with aldehydes into 2-aryl-1-(arylmethyl-1H-benzimidazoles under microwave irradiation

Directory of Open Access Journals (Sweden)

DAVOOD AZARIF

2010-09-01

Full Text Available An efficient and simple procedure was developed for the green synthesis of various 2-aryl-1-(arylmethyl-1H-benzimidazoles in high yields by acetic acid-promoted condensation of o-phenylenediamine with aldehydes in air under microwave irradiation and transition metal catalyst-free conditions.

Effects of disorder on the microwave properties of MgB2 polycrystalline films

International Nuclear Information System (INIS)

Ghigo, G.; Gerbaldo, R.; Gozzelino, L.; Laviano, F.; Mezzetti, E.; Ummarino, G. A.

2006-01-01

The role of disorder in superconducting magnesium diboride (MgB 2 ) policrystalline films is investigated in the high frequency range by a coplanar microwave resonator technique. Two sources of disorder are considered, heavy-ion irradiation damage and sample ageing. Microwave measurements are analyzed in the framework of the two-gap model with strong interband scattering contribution. It turns out that disorder enhancement increases the interband scattering rate, resulting in a reduction of the surface resistance at low temperatures, due to a slight increase of the π gap. Moreover, increasing disorder at grain boundaries induces a nonmonotonic residual surface resistance, showing the features of a resistive behavior for the highest disorder level. Finally, the effects of the different kinds of disorder on the intrinsic and on the grain-boundary properties of the MgB 2 films are compared and discussed

Genetic effects of low-level irradiation

International Nuclear Information System (INIS)

Selby, P.B.

1980-01-01

Recent estimates of the genetic effects of radiation by two widely recognized committees (BEIR III and UNSCEAR 1977) are based to a large extent on data collected in mice using either the specific-locus method or the approach of empirically determining the nature and extent of radiation-induced genetic damage to the skeleton. Both committees made use of doubling-dose and direct methods of estimating genetic hazard. Their estimates can be applied to assessments of risk resulting from medical irradiation in terms both of risk to the population at large and to the individual

In-situ synthesis of reduced graphene oxide modified lithium vanadium phosphate for high-rate lithium-ion batteries via microwave irradiation

International Nuclear Information System (INIS)

Wang, Zhaozhi; Guo, Haifu; Yan, Peng

2015-01-01

Highlights: • Graphene-decorated Li 3 V 2 (PO 4 ) 3 is synthesized via microwave irradiation. • Both Li 3 V 2 (PO 4 ) 3 and RGO can be simultaneously achieved through this route. • The GO is reduced by microwave irradiation not the carbon. • Li 3 V 2 (PO 4 ) 3 /RGO displays excellent high-rate ability and cyclic stability. - Abstract: We report a simple and rapid method to synthesize graphene-modified Li 3 V 2 (PO 4 ) 3 as cathode material for lithium-ion batteries via microwave irradiation. By treating graphene oxide and the precursor of Li 3 V 2 (PO 4 ) 3 in a commercial microwave oven, both reduced graphene oxide and Li 3 V 2 (PO 4 ) 3 could be simultaneously synthesized within 5 min. The structure, morphology and electrochemical performances of as-synthesized graphene-modified Li 3 V 2 (PO 4 ) 3 are investigated systematically by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, charge/discharge tests, electrochemical impedance spectra (EIS) and cyclic voltammetry (CV). The XRD result indicates that single-phase graphene-modified Li 3 V 2 (PO 4 ) 3 with monoclinic structure can be obtained. Both SEM and TEM images show that Li 3 V 2 (PO 4 ) 3 nanocrystals are embedded in the reduced graphene oxide sheets which could provide an easy path for the electrons and Li-ions during the cycling process. Compared with the pristine Li 3 V 2 (PO 4 ) 3 electrode, graphene-modified Li 3 V 2 (PO 4 ) 3 exhibits a better high-rate ability and cyclic stability. These superior electrochemical performances are attributed to the good conductivity of reduced graphene oxide which enhances the electrons and Li-ions transport on the surface of Li 3 V 2 (PO 4 ) 3 . Thus, this simple and rapid method could be promising to synthesize graphene-modified electrode materials

Non-self-sustained microwave discharge and the concept of a microwave air jet engine

International Nuclear Information System (INIS)

Batanov, G M; Gritsinin, S I; Kossyi, I A

2002-01-01

A new type of microwave discharge - near-surface non-self-sustained discharge (NSND) - has been realized and investigated. A physical model of this discharge is presented. For the first time NSND application for microwave air jet engines has been proposed. Measurements under laboratory conditions modelling the microwave air jet engine operation shows the qualitative agreement between the model of NSND and actual processes near the target irradiated by a powerful microwave beam. Characteristic dependences of recoil momentum of target on the background pressure and microwave pulse duration obtained in experiments are presented. Measured cost of thrust produced by the NSND is no more than 3.0 kW N -1 , which is close to the predicted values

GREENER SYNTHESIS OF HETEROCYCLIC COMPOUNDS USING MICROWAVE IRRADIATION

Science.gov (United States)

An introduction of our interest in the microwave-assisted greener synthesis of a variety of heterocyclic compounds will be presented. It involves microwave (MW) exposure of neat reactants (undiluted) catalyzed by the surfaces of recyclable mineral supports, such as alumina, sili...

Vanishing microwave effects : influence of heterogeneity

NARCIS (Netherlands)

Dressen, M.H.C.L.; Kruijs, van de B.H.P.; Meuldijk, J.; Vekemans, J.A.J.M.; Hulshof, L.A.

2007-01-01

A consistent setup of experiments has been conducted to demonstrate an enhanced reaction rate under microwave irradiation as compared to conventional heating, i.e. a real microwave effect. It was found that addition of a cosolvent, diminishing the heterogeneous character of the reaction mixture,

Dehydration of sodium carbonate monohydrate with indirect microwave heating

International Nuclear Information System (INIS)

Seyrankaya, Abdullah; Ozalp, Baris

2006-01-01

In this study, dehydration of sodium carbonate monohydrate (Na 2 CO 3 .H 2 O) (SCM) in microwave (MW) field with silicon carbide (SiC) as an indirect heating medium was investigated. SCM samples containing up to 3% free moisture were placed in the microwave oven. The heating experiments showed that SCM is a poor microwave energy absorber for up to 6 min of irradiation at an 800 W of microwave power. The heat for SCM calcination is provided by SiC which absorbs microwave. The monohydrate is then converted to anhydrous sodium carbonate on the SiC plate by calcining, i.e. by removing the crystal water through heating of the monohydrate temperatures of over 120 deg. C. The calcination results in a solid phase recrystallization of the monohydrate into anhydrate. In the microwave irradiation process, dehydration of SCM in terms of indirect heating can be accelerated by increasing the microwave field power

Effect of low-dose gamma irradiation on enterotoxin-positive strains of Clostridium perfringens Type A

International Nuclear Information System (INIS)

Barnhart, H.M. Jr.

1976-01-01

The effect of low-dose gamma irradiation on selected enterotoxin producing strains of Clostridium perfringens Type A was studied. The radioresistance of three strains NCTC-8239, NCTC-10239 and NCTC-8798 in 0.1 percent peptone water, beef gravy and ground beef was determined for both vegetative cells and spores. D 10 values were approximately 30 Krad in 0.1 percent peptone water and 175 Krad in beef menstruums. D 10 values for spores were approximately 250 Krad in 0.1 percent peptone water and 335 Krad in beef. Low-level irradiation induced a 2 hr lag for cell recovery at 37 0 C following irradiation though this was strain dependent. Heat resistance of vegetative cells decreased following irradiation, although one strain was stimulated in growth response and unaltered in its heat resistance. Spore activation and germination were not affected by low-level irradiation. Spores were not significantly inactivated at this level. Irradiation had no effect on subsequent survival of vegetative cells stored at cold temperatures. Enterotoxin production by irradiated cultures was not affected by the irradiation treatment. A method for quantitating C. perfringens enterotoxin using crossed-immunoelectrophoresis was developed. It was found that this technique could detect at least .05 g of enterotoxin, could utilize crude enterotoxin preparations and was more sensitive than other methods based on biological activity

An approach of ionic liquids/lithium salts based microwave irradiation pretreatment followed by ultrasound-microwave synergistic extraction for two coumarins preparation from Cortex fraxini.

Science.gov (United States)

Liu, Zaizhi; Gu, Huiyan; Yang, Lei

2015-10-23

Ionic liquids/lithium salts solvent system was successfully introduced into the separation technique for the preparation of two coumarins (aesculin and aesculetin) from Cortex fraxini. Ionic liquids/lithium salts based microwave irradiation pretreatment followed by ultrasound-microwave synergy extraction (ILSMP-UMSE) procedure was developed and optimized for the sufficient extraction of these two analytes. Several variables which can potentially influence the extraction yields, including pretreatment time and temperature, [C4mim]Br concentration, LiAc content, ultrasound-microwave synergy extraction (UMSE) time, liquid-solid ratio, and UMSE power were optimized by Plackett-Burman design. Among seven variables, UMSE time, liquid-solid ratio, and UMSE power were the statistically significant variables and these three factors were further optimized by Box-Behnken design to predict optimal extraction conditions and find out operability ranges with maximum extraction yields. Under optimum operating conditions, ILSMP-UMSE showed higher extraction yields of two target compounds than those obtained by reference extraction solvents. Method validation studies also evidenced that ILSMP-UMSE is credible for the preparation of two coumarins from Cortex fraxini. This study is indicative of the proposed procedure that has huge application prospects for the preparation of natural products from plant materials. Copyright © 2015 Elsevier B.V. All rights reserved.

Further study of the glassy low-temperature properties of irradiated crystalline quartz: neutron and electron irradiation

International Nuclear Information System (INIS)

Laermans, C.; Daudin, B.

1979-01-01

Recently it has been shown that a quartz crystal after light fast neutron irradiation shows low temperature hypersonic properties which are similar to those found in glasses although the sample was still crystalline. Additional measurements have been carried out in the neutron-irradiated sample and a sample irradiated with high energy electrons has also been investigated. (Fast neutron dose 6 x 10 18 n/cm 2 , 2 MeV electron dose 3 x 10 19 e/cm 2 ). A magnetic field up to 1.5 T was found to have no influence in the hypersonic saturation behaviour of the neutron-irradiated sample (9 GHz, 1.65 K) and thermal conductivity measurements are consistent with a number of two level systems (2 LS) an order of magnitude lower than in vitreous silica as found before. Low temperature hypersonic measurements as a function of acoustic intensity and temperature as well as thermal conductivity measurements give no evidence for the presence of 2 LS in the electron irradiated sample. Considering the damage created in both samples this indicates that 2 LS are probably not related to point defects

Study on the synthesis and physicochemical properties of starch acetate with low substitution under microwave assistance.

Science.gov (United States)

Lin, Derong; Zhou, Wei; Zhao, Jingjing; Lan, Weijie; Chen, Rongming; Li, Yutong; Xing, Baoshan; Li, Zhuohao; Xiao, Mengshi; Wu, Zhijun; Li, Xindan; Chen, Rongna; Zhang, Xingwen; Chen, Hong; Zhang, Qing; Qin, Wen; Li, Suqing

2017-10-01

In this study, synthesis and physicochemical properties of starch acetate with low substitution under microwave were studied. A three-level-three-factorial Central Composite Design using Response Surface Methodology (RSM) was employed to optimize the reaction conditions. The optimal parameters are as follows: amount of acetic anhydride of 12%, radiation time of 11min, and microwave power of 100W. These optimal conditions predicted by RSM were confirmed that the degree of substitution (DS) of acetate starch is 0.0691mg/g and the physical and chemical properties of natural corn starch (NCS) and corn starch acetate (ACS) were further studied.The transparency, water separation, water absorption, expansion force, and solubility of ACS low substitution are better than NCS, while the NCS's hydrolysis percentage is higher than ACS, which indicate that the modified corn starch has better performance than native corn starch. The surface morphology of the corn starch acetate was examined by scanning electron microscope (SEM), which showed that it had a smooth surface and a spherical and polygonal shape. However, samples' shape is irregular. Crystal structure was observed by X-ray diffraction, and the ACS can determine the level of microwave technology that can destroy the extent of the crystal and amorphous regions. Fourier transform infrared (FTIR) spectroscopy shows that around 1750cm -1 carbonyl signal determines acetylation bonding successfully. Copyright © 2017 Elsevier B.V. All rights reserved.

An ESR protocol based on relaxation phenomena of irradiated Japanese pepper

Science.gov (United States)

Ukai, Mitsuko; Nakamura, Hideo; Shimoyama, Yuhei

2006-03-01

We found various free radicals in a commercially available pepper in Japan before and after irradiation using electron spin resonance (ESR) spectroscopy. The typical ESR spectrum of the pepper consists of a sextet centered at g = 2.0, a singlet at the same g-value and a singlet at g = 4.0. Upon gamma ray irradiation, a new pair of signals appeared in the pepper. The progressive saturation behavior (PSB) at various microwave power levels indicated quite different relaxation behaviors of those radicals. Namely, the peak intensity of the organic free radical component decreases in a monotonic fashion, whereas the Mn 2+ and Fe 3+ ESR signals substantially keep constant. This reflects the evidence of three independent radicals in the pepper before irradiation. The PSB of the pair peaks as induced by irradiation possessed quite different PSB from that of the free radical located at g = 2.0. We proposed a new protocol for the ESR detection of irradiated foods by the PSB method at different microwave power levels. This would call for a major modification of the CEN protocol in European Union.

Minimizing material damage using low temperature irradiation

International Nuclear Information System (INIS)

Craven, E.; Hasanain, F.; Winters, M.

2012-01-01

Scientific advancements in healthcare driven both by technological breakthroughs and an aging and increasingly obese population have lead to a changing medical device market. Complex products and devices are being developed to meet the demands of leading edge medical procedures. Specialized materials in these medical devices, including pharmaceuticals and biologics as well as exotic polymers present a challenge for radiation sterilization as many of these components cannot withstand conventional irradiation methods. The irradiation of materials at dry ice temperatures has emerged as a technique that can be used to decrease the radiation sensitivity of materials. The purpose of this study is to examine the effect of low temperature irradiation on a variety of polymer materials, and over a range of temperatures from 0 °C down to −80 °C. The effectiveness of microbial kill is also investigated under each of these conditions. The results of the study show that the effect of low temperature irradiation is material dependent and can alter the balance between crosslinking and chain scission of the polymer. Low temperatures also increase the dose required to achieve an equivalent microbiological kill, therefore dose setting exercises must be performed under the environmental conditions of use. - Highlights: ► A study is performed to quantify low temperature irradiation effects on polymer materials and BIs. ► Low temperature irradiation alters the balance of cross-linking and chain scissoning in polymers. ► Low temperatures provide radioprotection for BIs. ► Benefits of low temperatures are application specific and must be considered when dose setting.

Microwave-Assisted Selective Hydrogenation of Furfural to Furfuryl Alcohol Employing a Green and Noble Metal-Free Copper Catalyst.

Science.gov (United States)

Romano, Pedro N; de Almeida, João M A R; Carvalho, Yuri; Priecel, Peter; Falabella Sousa-Aguiar, Eduardo; Lopez-Sanchez, Jose A

2016-12-20

Green, inexpensive, and robust copper-based heterogeneous catalysts achieve 100 % conversion and 99 % selectivity in the conversion of furfural to furfuryl alcohol when using cyclopentyl-methyl ether as green solvent and microwave reactors at low H 2 pressures and mild temperatures. The utilization of pressurized microwave reactors produces a 3-4 fold increase in conversion and an unexpected enhancement in selectivity as compared to the reaction carried out at the same conditions using conventional autoclave reactors. The enhancement in catalytic rate produced by microwave irradiation is temperature dependent. This work highlights that using microwave irradiation in the catalytic hydrogenation of biomass-derived compounds is a very strong tool for biomass upgrade that offers immense potential in a large number of transformations where it could be a determining factor for commercial exploitation. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Microwave effects in Drosophila melanogaster

International Nuclear Information System (INIS)

Dardalhon, M.; Averbeck, D.; Berteaud, A.J.

1979-01-01

Experiments were set up to investigate the effects of open space microwave irradiation of the millimeter (73 GHz) and the centimeter (17 GHz) range in Drosophila melanogaster. We used the wild type strain Paris and the strain delta carrying melanitic tumors in the 3rd larval stage, in the pupae and the adults. The power densities were up to 100mW.cm -2 for 73 GHz and about 60 mW.cm -2 for microwaves at 17 GHz. After 2h exposure to microwaves of 17 GHz or 73 GHz the hatching of the irradiated eggs and their development were normal. In a few cases there was a tendency towards a diminution of the survival of eggs treated at different stages, of larvae treated in the stages 1, 2 and 3 and of treated pupae. However, this was not always statistically significant. The microwave treatment did not induce teratological changes in the adults. A statistical analysis brought about slight diminutions in the incidence and multiplicity of tumors in adult flies. When wild type females were exposed to microwaves of 17 GHz for 16 or 21 h and crossed with untreated males we observed a marked increase in fertility as compared to untreated samples. The viability and tumor incidence in the offspring was not affected. Similar results were obtained when microwaves treated males were crossed with untreated females

Synthesis of nitrogen-doped graphene via solid microwave method

Energy Technology Data Exchange (ETDEWEB)

Zhang, Li, E-mail: zhangli379@sohu.com [School of Electrical Engineering, Dalian University of Technology, Dalian, Liaoning 116024 (China); Ji, Bingcheng, E-mail: debbo.jee@outlook.com [School of Electrical Engineering, Dalian University of Technology, Dalian, Liaoning 116024 (China); Wang, Kai [School of Electrical Engineering, Dalian University of Technology, Dalian, Liaoning 116024 (China); Song, Jinyan [School of Information Engineering, Dalian Ocean University, Dalian, Liaoning 116024 (China)

2014-07-01

Graphical abstract: - Highlights: • A direct solid microwave method is developed to prepare nitrogen-doped graphene. • The method consists of two steps, namely the functionalization and microwave irradiation. • Melamine can serve as not only functionalizing agent but also nitrogen source. - Abstract: In this paper, we propose a solid microwave-mediated method for scalable production of nitrogen-doped graphene sheets (NGS) using low-cost industrial material melamine as functionalizing agent and nitrogen source. The strong interaction of microwaves with graphene oxide has been fully utilized to generate in situ heating that induces the decompose melamine and nitrogen doping of graphene. The morphology, structure, and components of the as-produced nitrogen-doped graphene are characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM), Brunauer–Emmett–Teller (BET), pore-size distribution (PSD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectra (XPS), X-ray diffraction (XRD), and Raman spectroscopy. The results show NGS can be successfully synthesized via this strategy.

Synthesis of nitrogen-doped graphene via solid microwave method

International Nuclear Information System (INIS)

Zhang, Li; Ji, Bingcheng; Wang, Kai; Song, Jinyan

2014-01-01

Graphical abstract: - Highlights: • A direct solid microwave method is developed to prepare nitrogen-doped graphene. • The method consists of two steps, namely the functionalization and microwave irradiation. • Melamine can serve as not only functionalizing agent but also nitrogen source. - Abstract: In this paper, we propose a solid microwave-mediated method for scalable production of nitrogen-doped graphene sheets (NGS) using low-cost industrial material melamine as functionalizing agent and nitrogen source. The strong interaction of microwaves with graphene oxide has been fully utilized to generate in situ heating that induces the decompose melamine and nitrogen doping of graphene. The morphology, structure, and components of the as-produced nitrogen-doped graphene are characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM), Brunauer–Emmett–Teller (BET), pore-size distribution (PSD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectra (XPS), X-ray diffraction (XRD), and Raman spectroscopy. The results show NGS can be successfully synthesized via this strategy

Pre-irradiation at a low dose-rate blunted p53 response

International Nuclear Information System (INIS)

Takahashi, A.; Ohnishi, K.; Asakawa, I.; Tamamoto, T.; Yasumoto, J.; Yuki, K.; Ohnishi, T.; Tachibana, A.

2003-01-01

Full text: We have studied whether the p53-centered signal transduction pathway induced by acute radiation is interfered with chronic pre-irradiation at a low dose-rate in human cultured cells and whole body of mice. In squamous cell carcinoma cells, we found that a challenge irradiation with X-ray immediately after chronic irradiation resulted in lower levels of p53 than those observed after the challenge irradiation alone. In addition, the induction of p53-centered apoptosis and the accumulation of its related proteins after the challenge irradiation were strongly correlated with the above-mentioned phenomena. In mouse spleen, the induction of apoptosis and the accumulation of p53 and Bax were observed dose-dependently at 12 h after a challenge irradiation. In contrast, we found significant suppression of them induced by challenge irradiation at a high dose-rate when mice were pre-irradiated with chronic irradiation at a low dose-rate. These findings suggest that chronic pre-irradiation suppressed the p53 function through radiation-induced p53-dependent signal transduction processes. There are numerous papers about p53 functions in apoptosis, radiosensitivity, genomic instability and cancer incidence in cultured cells or animals. According to our data and other findings, since p53 can prevent carcinogenesis, pre-irradiation at a low dose-rate might enhance the predisposition to cancer. Therefore, it is possible that different maximal permissible dose equivalents for the public populations are appropriate. Furthermore, concerning health of human beings, studies of the adaptive responses to radiation are quite important, because the radiation response strongly depends on experience of prior exposure to radiation

Microwave irradiation - a closer look at heating efficiencies

NARCIS (Netherlands)

Hoogenboom, R.; Wilms, T.F.A.; Schubert, U.S.

2008-01-01

Microwave irradn. is rapidly evolving into a common heat source in different areas of chem. including medicinal and org. chem. as well as polymer chem. The major advantages of the use of microwave irradn. are the often obsd. faster and cleaner reactions and sometimes changes in selectivity. Although

Thermoluminescence analysis of co-doped NaCl at low temperature irradiations

Energy Technology Data Exchange (ETDEWEB)

Cruz-Zaragoza, E., E-mail: ecruz@nucleares.unam.m [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, A.P. 70-543, 04510 Mexico D.F. (Mexico); Ortiz, A. [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, A.P. 70-543, 04510 Mexico D.F. (Mexico); Unidad Profesional Interdisciplinaria de Ingenieria y Tecnologias Avanzadas, IPN, Av. Instituto Politecnico Nacional 2580, Col. La Laguna Ticoman, 07340 Mexico D.F. (Mexico); Furetta, C. [Touro University Rome, Circne Gianicolense 15-17, 00153 Rome (Italy); Flores J, C.; Hernandez A, J.; Murrieta S, H. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, A.P. 20-364, 01000 Mexico D.F. (Mexico)

2011-02-15

The thermoluminescent response and kinetics parameters of NaCl, doubly activated by Ca-Mn and Cd-Mn ions, exposed to gamma radiation are analyzed. The doped NaCl samples were irradiated at relative low temperature, i.e. at the liquid nitrogen temperature (LNT) and at dry ice temperature (DIT), and the glow curves obtained after 2 Gy of gamma irradiation were analyzed using the computerized glow curve deconvolution (CGCD). An evident variation in the glow curve structure after LNT and DIT was observed. It seems that different kinds of trapping levels are activated at relative low temperature. The original two prominent peaks in compositions A (Ca,Mn) and B (Ca,Mn) have been changed in only one main peak with satellites in the low temperature side of the glow curves. In compositions C (Cd,Mn) and D (Cd,Mn), low temperature peaks become stronger and prominent than the high temperature peaks; this effect could be explained considering that the trapping probability for low temperature traps, the one very close to the conduction band, is enhanced by low temperatures during irradiation.

Effect of microwave irradiation on germination and seedling growth physiological characteristics of alfalfa seeds after storage

International Nuclear Information System (INIS)

Chen Liyu; Zhang Shuqing; Li Jianfeng; Shi Shangli; Huo Pinghui

2012-01-01

In order to study the effect of microwave irradiation on germination and growth physiological characteristics of seeds that stored for years, the irradiated alfalfa seeds that stored at room temperature for 2 years were used to conduct the germination and pot culture tests, and the germination rate, radical elongation, growth height, individual nodule, nitrogenase activity, chlorophyll content and chlorophyll fluorescence parameters were measured. On the 15th day of germination, the germination rates of all the treatments are higher than that of the control, which decrease with the elongation of time. On the llst day of germination, the radical length of all the treatments is lower than that of the control. Growth height, individual nodule, fresh weight and dry weight for the 40 s irradiation treatment are higher than that of the control. Nitrogenase activity of all the treatments is lower than that of the control (P < O.05). The chlorophyll content reaches its maximum when being irradiated for 10 s, and the variation for F 0 and F v /F m of all treatments indicates that the light conversion efficiency of the leaves derived from the irradiated alfalfa seeds that stored for 2 a at room temperature is still relatively stressed. (authors)

Epidemiological survey of the effects of low level radiation dose: a comparative assessment

Energy Technology Data Exchange (ETDEWEB)

Rose, K.S.B.

1993-10-01

This volume presents the collations tables of a six volume comparative epidemiological survey of the effects of low level radiation dose. Data are collated for the effects observed in the following irradiated groups:- Preconception irradiation, intra-uterine irradiation, childhood irradiation, adult irradiation. (UK).

Microwave-assisted silica-promoted solvent-free synthesis of ...

Indian Academy of Sciences (India)

method using microwave irradiation with an excellent yield. The newly ... Table 1. Silica promoted microwave-assisted solvent-free synthesis of quinazolinone ... Time (min). Yield (%)a ..... thanks SC/ST cell of Bangalore University for research.

Microwave assisted synthesis of MnO2 on nickel foam-graphene for electrochemical capacitor

International Nuclear Information System (INIS)

Bello, A.; Fashedemi, O.O.; Fabiane, M.; Lekitima, J.N.; Ozoemena, K.I.; Manyala, N.

2013-01-01

Highlights: •Three-dimensional synthesis of graphene using CVD. •Hydrothermal deposition (microwave irradiation) of MnO 2 on graphene. •Morphologies of the composite reveals flower-like nanostructures of MnO 2 on graphene. •Composite exhibit excellent electrochemical performance. -- Abstract: A green chemistry approach (hydrothermal microwave irradiation) has been used to deposit manganese oxide on nickel foam-graphene. The 3D graphene was synthesized using nickel foam template by chemical vapor deposition (CVD) technique. Raman spectroscopy, X-ray diffraction (XRD), scanning electron and transmission electron microscopies (SEM and TEM) have been used to characterize structure and surface morphology of the composite, respectively. The Raman spectroscopy measurements on the samples reveal that 3D graphene consists of mostly few layers with low defect density. The composite was tested in a three electrode configuration for electrochemical capacitor, and exhibited a specific capacitance of 305 F g −1 at a current density of 1 A g −1 and showed excellent cycling stability. The obtained results demonstrate that microwave irradiation technique could be a promising approach to synthesis graphene based functional materials for electrochemical applications

Comparison of low-level polycyclic aromatic hydrocarbons in sediment revealed by Soxhlet extraction, microwave-assisted extraction, and pressurized liquid extraction

International Nuclear Information System (INIS)

Itoh, Nobuyasu; Numata, Masahiko; Aoyagi, Yoshie; Yarita, Takashi

2008-01-01

We analyzed polycyclic aromatic hydrocarbons (PAHs) present in lake sediment at low levels ( -1 ) by using Soxhlet extraction (Soxhlet), microwave-assisted extraction (MAE), and pressurized liquid extraction (PLE) in combination with gas chromatography and isotope-dilution mass spectrometry. Although all extraction techniques showed good repeatability for five target PAHs (relative standard deviation MAE > Soxhlet. Differences in the results originated mainly from differences in the extraction efficiencies of the techniques for native PAHs, because all techniques gave comparable recovery yields of corresponding 13 C-labeled PAHs ( 13 C-PAHs) (51-84%). Since non-negligible amounts of both native PAHs and 13 C-PAHs were re-adsorbed on matrix in MAE, not only recovery yields of 13 C-PAHs but also efficiencies of extraction of native PAHs should be examined to evaluate the appropriateness of any analytical procedures

The Lack of Cytotoxic Effect and Radioadaptive Response in Splenocytes of Mice Exposed to Low Level Internal β-Particle Irradiation through Tritiated Drinking Water in Vivo

Directory of Open Access Journals (Sweden)

Matthew Flegal

2013-12-01

Full Text Available Health effects of tritium, a β-emitter and a by-product of the nuclear industry, is a subject of significant controversy. This mouse in vivo study was undertaken to monitor biological effects of low level tritium exposure. Mice were exposed to tritiated drinking water (HTO at 10 KBq/L, 1 MBq/L and 20 MBq/L concentrations for one month. The treatment did not result in a significant increase of apoptosis in splenocytes. To examine if this low level tritium exposure alters radiosensitivity, the extracted splenocytes were challenged in vitro with 2 Gy γ-radiation, and apoptotic responses at 1 and 24 h were measured. No alterations in the radiosensitivity were detected in cells from mice exposed to tritium compared to sham-treated mice. In contrast, low dose γ-irradiation at 20 or 100 mGy, resulted in a significant increase in resistance to apoptotic cell death after 2 Gy irradiation; an indication of the radioadaptive response. Overall, our data suggest that low concentrations of tritium given to mice as HTO in drinking water do not exert cytotoxic effect in splenocytes, nor do they change cellular sensitivity to additional high dose γ-radiation. The latter may be considered as the lack of a radioadaptive response, typically observed after low dose γ-irradiation.

Influences of doping Cr/Fe/Ta on the performance of Ni/CeO{sub 2} catalyst under microwave irradiation in dry reforming of CH{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Odedairo, Taiwo [School of Chemical Engineering, The University of Queensland, St Lucia, Brisbane (Australia); Ma, Jun [School of Engineering, University of South Australia, Mawson Lakes, SA (Australia); Chen, Jiuling, E-mail: cjlchen@yahoo.com [School of Chemical Engineering, The University of Queensland, St Lucia, Brisbane (Australia); Wang, Shaobin [Department of Chemical Engineering, Curtin University, GPO Box U1987, Perth, WA 6845 (Australia); Zhu, Zhonghua, E-mail: z.zhu@uq.edu.au [School of Chemical Engineering, The University of Queensland, St Lucia, Brisbane (Australia)

2016-01-15

The structure of Ni/CeO{sub 2} catalyst with doping of Cr, Fe and Ta was investigated with XRD, N{sub 2} physisorption, XPS and HRTEM and the catalytic activity of the catalysts under microwave irradiation in dry reforming of methane was tested in a microwave reactor. The results show that the introduction of Cr and Ta to Ni/CeO{sub 2} can enhance the interaction between Ni and the support/promoter and inhibit the enlargement of NiO particles during the synthesis. The CH{sub 4} conversions in dry reforming on the catalysts follow the order: Ni/CeO{sub 2}<2Fe–Ni<2Ta–Ni<2Cr–Ni. The superior performance of 2Ta–Ni and 2Cr–Ni may be attributed to the locally-heated Ni particles caused by the strong microwave absorption of the in-situ grown graphene attached on them under microwave irradiation. - Highlights: • The influences of doping Cr, Fe and Ta on Ni/CeO{sub 2} were investigated. • The catalytic performances before and after doping were investigated. • The in-situ grown graphene can promote the conversion of reactants.

Microwave Assisted Synthesis of N-Arylheterocyclic Substituted-4-aminoquinazoline Derivatives

Directory of Open Access Journals (Sweden)

Ping Lu

2006-04-01

Full Text Available A simple, efficient, and general method has been developed for the synthesis of various N-aryl heterocylic substituted-4-aminoquinazoline compounds from 4-chloro- quinazoline and aryl heterocyclic amines under microwave irradiation using 2-propanol as solvent. The advantages of the use of microwave irradiation in relation to the classical method were demonstrated.

Poly(4-vinylphenol) gate insulator with cross-linking using a rapid low-power microwave induction heating scheme for organic thin-film-transistors

Science.gov (United States)

Fan, Ching-Lin; Shang, Ming-Chi; Hsia, Mao-Yuan; Wang, Shea-Jue; Huang, Bohr-Ran; Lee, Win-Der

2016-03-01

A Microwave-Induction Heating (MIH) scheme is proposed for the poly(4-vinylphenol) (PVP) gate insulator cross-linking process to replace the traditional oven heating cross-linking process. The cross-linking time is significantly decreased from 1 h to 5 min by heating the metal below the PVP layer using microwave irradiation. The necessary microwave power was substantially reduced to about 50 W by decreasing the chamber pressure. The MIH scheme is a good candidate to replace traditional thermal heating for cross-linking of PVP as the gate insulator for organic thin-film-transistors.

Microwave pulse generation by photoconductive switching

Energy Technology Data Exchange (ETDEWEB)

Pocha, M.D.; Druce, R.L.

1989-03-14

Laser activated photoconductive semiconductor switching shows significant potential for application in high power microwave generation. Primary advantages of this concept are: small size, light weight, ruggedness, precise timing and phasing by optical control, and the potential for high peak power in short pulses. Several concepts have been suggested for microwave generation using this technology. They generally fall into two categories (1) the frozen wave generator or (2) tuned cavity modulation, both of which require only fast closing switches. We have been exploring a third possibility requiring fast closing and opening switches, that is the direct modulation of the switch at microwave frequencies. Switches have been fabricated at LLNL using neutron irradiated Gallium Arsenide which exhibit response times as short as 50 ps at low voltages. We are in the process of performing high voltage tests. So far, we have been able to generate 2.4 kV pulses with approximately 340 ps response time (FWHM) using approximately a 200..mu..J optical pulse. Experiments are continuing to increase the voltage and improve the switching efficiency. 3 refs., 6 figs.

Microwave pulse generation by photoconductive switching

Science.gov (United States)

Pocha, M. D.; Druce, R. L.

1989-03-01

Laser activated photoconductive semiconductor switching shows significant potential for application in high power microwave generation. Primary advantages of this concept are: small size, light weight, ruggedness, precise timing and phasing by optical control, and the potential for high peak power in short pulses. Several concepts have been suggested for microwave generation using this technology. They generally fall into two categories: (1) the frozen wave generator, or (2) tuned cavity modulation, both of which require only fast closing switches. We have been exploring a third possibility requiring fast closing and opening switches, that is the direct modulation of the switch at microwave frequencies. Switches have been fabricated at LLNL using neutron irradiated Gallium Arsenide which exhibit response times as short as 50 ps at low voltages. We are in the process of performing high voltage tests. So far, we have been able to generate 2.4 kV pulses with approximately 340 ps response time (FWHM) using approximately a 200 microJ optical pulse. Experiments are continuing to increase the voltage and improve the switching efficiency.

Microwave-assisted low temperature fabrication of ZnO thin film electrodes for solar energy harvesting

Energy Technology Data Exchange (ETDEWEB)

Nirmal Peiris, T.A.; Sagu, Jagdeep S.; Hazim Yusof, Y.; Upul Wijayantha, K.G., E-mail: U.Wijayantha@lboro.ac.uk

2015-09-01

Metallic Zn thin films were electrodeposited on fluorine-doped tin oxide (FTO) glass substrates and oxidized under air by conventional radiant and microwave post-annealing methods to obtain ZnO thin film electrodes. The temperature of each post-annealing method was varied systematically and the photoelectrochemical (PEC) performance of electrodes was evaluated. The best photocurrent density achieved by the conventional radiant annealing method at 425 °C for 15 min was 93 μA cm{sup −2} at 1.23 V vs. NHE and the electrode showed an incident photon-to-electron conversion efficiency (IPCE) of 28.2%. X-ray diffractogram of this electrode showed that the oxidation of Zn to ZnO was not completed during the radiant annealing process as evident by the presence of metallic Zn in the electrode. For the electrode oxidized from Zn to ZnO under microwave irradiation, a photocurrent of 130 μA cm{sup −2} at 1.23 V vs. NHE and IPCE of 35.6% was observed after annealing for just 3 min, during which the temperature reached 250 °C. The photocurrent was 40% higher for the microwave annealed sample; this increase was attributed to higher surface area by preserving the nanostructure, confirmed by SEM surface topographical analysis, and better conversion yields to crystalline ZnO. Overall, it was demonstrated that oxidation of Zn to ZnO can be accomplished by microwave annealing five times faster than that of conventional annealing, thus resulting in a ~ 75% power saving. This study shows that microwave processing of materials offers significant economic and performance advantages for industrial scale up. - Highlights: • Conversion of Zn to ZnO by microwave and radiant annealing was conducted. • Microwave conversion was 5 times faster compared to radiant annealing. • Photoelectrochemical performance of microwave annealed ZnO was 40% higher. • Microwave annealing results in a 75% energy saving.

Effect of microwave treatment to acanthamoeba: a possibility of contact lens storage case sterilization?

International Nuclear Information System (INIS)

Hiti, K.; Faschinger, C.; Haller-Schober, E.M.; Walochnik, J.; Aspoeck, H.; Hiti, B.

2003-01-01

Microbially contaminated contact lens storage cases are considered to be a predisposing risk factor for Acanthamoeba keratitis. What kind of effect does microwave irradiation have on contact lens cases contaminated with Acanthamoeba cysts and trophozoites? Different types of contact lens cases were contaminated with trophozoites and cysts of three different Acanthamoeba species (A. hatchetti, A. castellanii, A. comandoni) and exposed to microwave irradiation for 3, 5 and 8 minutes respectively. One of the three test series was run with dehydrated cysts. After an irradiation period of 3 minutes under humid conditions cysts and trophozoites of all three strains were completely destroyed. Dehydrated cysts of A. hatchetti and A. castellanii were not killed by irradiation. There were no negative effects of irradiation on the contact lens cases themselves. Acanthamoeba cysts and trophozoites are effectively killed by microwave irradiation on condition that irradiation takes place in humid conditions. This can be easily achieved by filling the contact lens storage cases with tap water. We recommend microwave irradiation as a cheap and save method for the sterilization of contact lens cases in order to avoid a possible Acanthamoeba infection of the eye. (author)

Identification of irradiated oysters by EPR measurements on shells

International Nuclear Information System (INIS)

Della Monaca, S.; Fattibene, P.; Boniglia, C.; Gargiulo, R.; Bortolin, E.

2011-01-01

In this paper the EPR spectra of the radicals induced in oyster shells after irradiation to (0.5-2) kGy ionizing radiation doses are analyzed. EPR spectra of irradiated shells showed the complex radical composition of biocarbonates, characterized by the presence of SO 2 - , SO 3 - and CO 2 - radicals with different symmetries. In particular, the radiation-induced line at g = 2.0038, due to the g x component of the orthorhombic SO 3 - , was well distinguishable from the rest of the spectrum. The g x component of the orthorhombic SO 3 - was found to be intense and stable enough to allow the identification at least for the whole shelf life of the oyster. Furthermore, it is still well visible at low microwave powers for which the other signals are weak or non-visible and has a linear dose response in the (0.5-2) kGy range. A possible procedure protocol for the identification of irradiated oysters, can be based on acquisitions of the spectrum at low microwave power values (tenths of milliWatt) and low modulation amplitude values (0.03-0.05 mT) and on the identification of the g = 2.0038 signal as a proof of the ionizing radiation treatment performed on the sample.

Influence of microwaves on the leaching kinetics of uraninite from a low grade ore in dilute sulfuric acid

International Nuclear Information System (INIS)

Madakkaruppan, V.; Pius, Anitha; Sreenivas, T.; Giri, Nitai; Sarbajna, Chanchal

2016-01-01

Highlights: • U leaching from a low-grade Si-rich ore studied in H_2SO_4 medium with (MW) irradiation. • MW heating is more efficient in terms of U recovery, kinetics and purity of liquor. • U leachability of 84% obtained in 90 min at 95 °C with 0.38 M H_2SO_4 at 450 mVwith MW heating • Conventional conductive heating gave about 74% leachability with less purity liquor. • U leaching was found follow product layer diffusion as controlling mechanism. - Abstract: This paper describes a study on microwave assisted leaching of uranium from a low-grade ore of Indian origin. The host rock for uranium mineralization is chlorite-biotite-muscovite-quartzo-feldspathic schist. The dominant presence of siliceous minerals determined leaching of uranium values in sulfuric acid medium under oxidizing conditions. Process parametric studies like the effect of sulfuric acid concentration (0.12–0.50 M), redox potential (400–500 mV), particle size (600–300 μm) and temperature (35°–95 °C) indicated that microwave assisted leaching is more efficient in terms of overall uranium dissolution, kinetics and provide relatively less impurities (Si, Al, Mg and Fe) in the leach liquor compared to conventional conductive leaching. The kinetics of leaching followed shrinking core model with product layer diffusion as controlling mechanism.

Influence of microwaves on the leaching kinetics of uraninite from a low grade ore in dilute sulfuric acid

Energy Technology Data Exchange (ETDEWEB)

Madakkaruppan, V. [Atomic Minerals Directorate for Exploration and Research, Begumpet, Hyderabad 500016 (India); Pius, Anitha, E-mail: dranithapius@gmail.com [Department of Chemistry, Gandhigram Rural Institute, Gandhigram, Dindigul District, Tamil Nadu 624302 (India); Sreenivas, T.; Giri, Nitai [Mineral Processing Division, Bhabha Atomic Research Center, AMD Complex, Begumpet, Hyderabad 500016 (India); Sarbajna, Chanchal [Atomic Minerals Directorate for Exploration and Research, Begumpet, Hyderabad 500016 (India)

2016-08-05

Highlights: • U leaching from a low-grade Si-rich ore studied in H{sub 2}SO{sub 4} medium with (MW) irradiation. • MW heating is more efficient in terms of U recovery, kinetics and purity of liquor. • U leachability of 84% obtained in 90 min at 95 °C with 0.38 M H{sub 2}SO{sub 4} at 450 mVwith MW heating • Conventional conductive heating gave about 74% leachability with less purity liquor. • U leaching was found follow product layer diffusion as controlling mechanism. - Abstract: This paper describes a study on microwave assisted leaching of uranium from a low-grade ore of Indian origin. The host rock for uranium mineralization is chlorite-biotite-muscovite-quartzo-feldspathic schist. The dominant presence of siliceous minerals determined leaching of uranium values in sulfuric acid medium under oxidizing conditions. Process parametric studies like the effect of sulfuric acid concentration (0.12–0.50 M), redox potential (400–500 mV), particle size (600–300 μm) and temperature (35°–95 °C) indicated that microwave assisted leaching is more efficient in terms of overall uranium dissolution, kinetics and provide relatively less impurities (Si, Al, Mg and Fe) in the leach liquor compared to conventional conductive leaching. The kinetics of leaching followed shrinking core model with product layer diffusion as controlling mechanism.

Adhesive bonding using variable frequency microwave energy

Science.gov (United States)

Lauf, Robert J.; McMillan, April D.; Paulauskas, Felix L.; Fathi, Zakaryae; Wei, Jianghua

1998-01-01

Methods of facilitating the adhesive bonding of various components with variable frequency microwave energy are disclosed. The time required to cure a polymeric adhesive is decreased by placing components to be bonded via the adhesive in a microwave heating apparatus having a multimode cavity and irradiated with microwaves of varying frequencies. Methods of uniformly heating various articles having conductive fibers disposed therein are provided. Microwave energy may be selectively oriented to enter an edge portion of an article having conductive fibers therein. An edge portion of an article having conductive fibers therein may be selectively shielded from microwave energy.

The effect of low-dose neutron irradiation on extracellular matrix

International Nuclear Information System (INIS)

Chen Tiehe; Lu Yongjie; Chai Mingsheng; Peng Wulin; Yang Yifang; Pan Yan; Chen Jinguo

2003-01-01

Projective: To study the effect of neutron irradiation on extracellular matrix. Methods: 120 male wistar rats were divided into four groups at random, and then exposed to neutron of 252 Cf-source at the doses of 0, 0.29, 0.62 and 1.20 Gy, respectively. After the exposure of 3 days, 1 month and 2 months, the rats were sacrificed and lung tissue specimens stored at -30 degree C. Hyaluronan, laminin, type III procollagen and type IV collagen in the lung tissue were detected by the method of radioimmunoassay. Results: The differences of the levels of hyaluronan in lung tissue among the groups were unsignificant. The levels of laminin in 0.29, 0.62 and 1.20 Gy groups after the 3-day exposure were remarkably different to those of the control group, and unable to recover completely even 2 months after the exposure. The levels of type IV collagen in higher three irradiated groups were all higher, but not significantly. The levels of type III procollagen in the early stage after exposure were higher, and later they lowered. Conclusion: The levels of some components of extracellular matrix in the lung tissue of rat can be changed by low-dose of neutron irradiation, but their variational modes and degrees depend on the dose of neutron irradiation and the length of period after exposure

High power pulsed/microwave technologies for electron accelerators vis a vis 10MeV, 10kW electron LINAC for food irradiation at CAT

International Nuclear Information System (INIS)

Shrivastava, Purushottam; Mulchandani, J.; Mohania, P.; Baxy, D.; Wanmode, Y.; Hannurkar, P.R.

2005-01-01

Use of electron accelerators for irradiation of food items is gathering momentum in India. The various technologies for powering the electron LINAC were needed to be developed in the country due to embargo situations as well as reservations of the developers worldwide to share the information related to this development. Centre for Advanced Technology, CAT, Indore, is engaged in the development of particle accelerators for medical industrial and scientific applications. Amongst other electron accelerators developed in CAT, a 10MeV, 10kW LINAC for irradiation of food items has been commissioned and tested for full rated 10kW beam power. The high power pulsed microwave driver for the LINAC was designed, developed and commissioned with full indigenous efforts, and is right now operational at CAT. It consists of a 6MW, 25kW S-band pulsed klystron, 15MW peak power pulse modulator system for the klystron, microwave driver amplifier chain, stabilized generator, protection and control electronics, waveguide system to handle the high peak and average power, gun modulator electronics, grid electronics etc. The present paper highlights various technologies like the pulsed power systems and components, microwave circuits and systems etc. Also the performance results of the high power microwave driver for the 10MeV LINAC at CAT are discussed. Future strategies for developing the state of art technologies are highlighted. (author)

Defects in low temperature electron irradiated InP

International Nuclear Information System (INIS)

Suski, J.; Bourgoin, J.

1984-01-01

n and p-InP has been irradiated at 25K with 1MeV electrons and the created defects were studied by deep level transient spectroscopy (DLTS) in the range 25K-400K. In n-InP, four traps are directly observed, with low introduction rates except for one. They anneal in three stages, and four new centers of still lower concentration appear after 70 0 C heat treatment. In p-InP, two dominant traps stable up to approx.= 400K with introduction rates close to the theoretical ones, which might be primary defects are found, while another one is clearly a secondary defect likely associated to Zn dopant. At least two of the low concentration irradiation induced electron traps, created between 25K and 100K are also secondary defects, which implies a mobility of some primary defects down to 100K at least. (author)

Quinacrine pretreatment reduces microwave-induced neuronal damage by stabilizing the cell membrane

Science.gov (United States)

Ding, Xue-feng; Wu, Yan; Qu, Wen-rui; Fan, Ming; Zhao, Yong-qi

2018-01-01

Quinacrine, widely used to treat parasitic diseases, binds to cell membranes. We previously found that quinacrine pretreatment reduced microwave radiation damage in rat hippocampal neurons, but the molecular mechanism remains poorly understood. Considering the thermal effects of microwave radiation and the protective effects of quinacrine on heat damage in cells, we hypothesized that quinacrine would prevent microwave radiation damage to cells in a mechanism associated with cell membrane stability. To test this, we used retinoic acid to induce PC12 cells to differentiate into neuron-like cells. We then pretreated the neurons with quinacrine (20 and 40 mM) and irradiated them with 50 mW/cm2 microwaves for 3 or 6 hours. Flow cytometry, atomic force microscopy and western blot assays revealed that irradiated cells pretreated with quinacrine showed markedly less apoptosis, necrosis, and membrane damage, and greater expression of heat shock protein 70, than cells exposed to microwave irradiation alone. These results suggest that quinacrine stabilizes the neuronal membrane structure by upregulating the expression of heat shock protein 70, thus reducing neuronal injury caused by microwave radiation. PMID:29623929

Copolyacrylates with phenylalanine and anthracene entities prepared by ATRP and microwave irradiation

Energy Technology Data Exchange (ETDEWEB)

Buruiana, E.C., E-mail: emilbur@icmpp.r [Romanian Academy, Petru Poni Institute of Macromolecular Chemistry, Grigore Ghica Voda Alley 41A, 700487 Iasi (Romania); Murariu, Mioara; Buruiana, Tinca [Romanian Academy, Petru Poni Institute of Macromolecular Chemistry, Grigore Ghica Voda Alley 41A, 700487 Iasi (Romania)

2010-10-15

In this study, two amino acid copolymers containing anthracene incorporated either on the one end, poly(N-acryloyl-L-phenylalanine-co-methyl methacrylate)-1 or as pendant groups, poly-(N-acryloyl-L-phenylalanine-co-methyl methacrylate)-2 were prepared directly from N-acryloyl-L-phenylalanine (APhe) and methyl methacrylate (MMA) through atom transfer radical polymerization (ATRP) and microwave-assisted synthesis. In the first case, 9-(chloromethyl)anthracene was used as an ATRP-initiator to obtain a copolymer that contains amino acid sequences and anthracene end-capped units (0.03 molar fraction). Rapid synthesis of copolymer under microwave irradiation (250 W) in the presence of 1,1'-azobis(cyclohexanecarbonitrile) used as an initiator was followed of a functionalization of the formed copolymer with an anthracene derivative yielding copolyacrylate with pendant anthracene (0.02 molar fraction). The structure of the copolymers was verified by {sup 1}H NMR, UV-Vis and FTIR spectroscopy, gel permeation chromatography (GPC), and fluorescence spectroscopy. The fluorescence quenching process of anthracene which exists in copolymers by FeCl{sub 3}, cobalt acetate, nitrobenzene, maleic anhydride, diethylaniline and nitromethane in DMF solutions shows that this involves an electron transfer between the excited state anthracene and the present transitional metal cations, more efficiently being FeCl{sub 3} for poly-(APhe-co-MMA)-1 and cobalt acetate for the latter copolymer.

Fuel ethanol production from sweet sorghum bagasse using microwave irradiation

International Nuclear Information System (INIS)

Marx, Sanette; Ndaba, Busiswa; Chiyanzu, Idan; Schabort, Corneels

2014-01-01

Sweet sorghum is a hardy crop that can be grown on marginal land and can provide both food and energy in an integrated food and energy system. Lignocellulose rich sweet sorghum bagasse (solid left over after starch and juice extraction) can be converted to bioethanol using a variety of technologies. The largest barrier to commercial production of fuel ethanol from lignocellulosic material remains the high processing costs associated with enzymatic hydrolysis and the use of acids and bases in the pretreatment step. In this paper, sweet sorghum bagasse was pretreated and hydrolysed in a single step using microwave irradiation. A total sugar yield of 820 g kg −1 was obtained in a 50 g kg −1 sulphuric acid solution in water, with a power input of 43.2 kJ g −1 of dry biomass (i.e. 20 min at 180 W power setting). An ethanol yield based on total sugar of 480 g kg −1 was obtained after 24 h of fermentation using a mixed culture of organisms. These results show the potential for producing as much as 0.252 m 3  tonne −1 or 33 m 3  ha −1 ethanol using only the lignocellulose part of the stalks, which is high enough to make the process economically attractive. - Highlights: • Different sweet sorghum cultivars were harvested at 3 and 6 months. • Sweet sorghum bagasse was converted to ethanol. • Microwave pretreatment and hydrolysis was done in a single step. • Sugar rich hydrolysates were converted to ethanol using co-fermentation

Stimulation effects of low dose-rate irradiation on pancreatic antioxidant activity in type II diabetes model mice

International Nuclear Information System (INIS)

Nomura, Takaharu; Sakai, Kazuo

2005-01-01

The effects of low dose-rate gamma irradiation on the type II diabetes mellitus were investigated in BKS.Cg-+Lepr db /+Lepr db /Jcl (DB mice). Ten-week-old female DB mice (5 mice in each group) were irradiated with gamma ray at 0.35, 0.70, or 1.2 mGy/hr. During the course of the 12 weeks the glucose level slightly increased with little difference between the irradiated and the non-irradiated groups. The plasma insulin concentration decreased within the first 4 weeks in all groups. The level was kept low in the non-irradiated mice; while the insulin level in the irradiated groups showed a tendency to increase. In the 0.70 mGy/hr group the increase was statistically significant after 12 weeks of irradiation. Total activity of SOD, one of antioxidative enzymes, decreased both in non-irradiated and irradiated groups; however the decrease was less in the irradiated groups, especially 0.70 mGy/hr group. In the 0.70 mGy/hr group Mn-SOD activity, one of the components of total SOD activity, increased after 12-week irradiation. A pathological examination of the pancreas revealed that damage to β cells responsible for the secretion of insulin was much less in the 0.70 mGy/hr group compared to that in the non-irradiated group. These results indicated that the low dose-rate irradiation increase the antioxidative capacity in the pancreas to protect β cells from oxidative damage, and the to increase the insulin level. This mechanism would lead the mice to the recovery from the disease and the prolongation of the life span as is demonstrated in our previous report. (author)

Modulation of surface structure and catalytic properties of cerium oxide nanoparticles by thermal and microwave synthesis techniques

Energy Technology Data Exchange (ETDEWEB)

He, Jian [College of Pharmacy, Third Military Medical University, Chongqing 400038 (China); Zhou, Lan; Liu, Jie; Yang, Lu; Zou, Ling; Xiang, Junyu; Dong, Shiwu [School of Biomedical Engineering, Third Military Medical University, Chongqing 400038 (China); Yang, Xiaochao, E-mail: xcyang@tmmu.edu.cn [School of Biomedical Engineering, Third Military Medical University, Chongqing 400038 (China)

2017-04-30

Highlights: • The CNPs synthesized by microwave irradiation have more reactive hot spots than that synthesized by convective heating. • The CNPs synthesized by microwave irradiation exhibited higher SOD activity than that synthesized by convective heating. • The CNPs synthesized by microwave irradiation heating could better protect cells from oxidative stress. - Abstract: Cerium oxide nanoparticles (CNPs) have been intensively explored for biomedical applications in recent few years due to the versatile enzyme mimetic activities of the nanoparticles. However, the control of CNPs quality through the optimization of synthesis conditions remains largely unexplored as most of the previous studies only focus on utilizing the catalytic activities of the nanoparticles. In the present study, CNPs with size about 5 nm were synthesized by thermal decomposition method using traditional convective heating and recently developed microwave irradiation as heating source. The quality of CNPs synthesized by the two heating manner was evaluated. The CNPs synthesized by convective heating were slightly smaller than that synthesized by microwave irradiation heating. The cores of the CNPs synthesized by the two heating manner have similar crystal structure. While the surface subtle structures of the CNPs synthesized by two heating manner were different. The CNPs synthesized by microwave irradiation have more surface reactive hot spot than that synthesized by convective heating as the nanoparticles responded more actively to the redox environment variation. This difference resulted in the higher superoxide dismutase (SOD) mimetic activity of CNPs synthesized by microwave irradiation heating than that of the convective heating. Preliminary experiments indicated that the CNPs synthesized by microwave irradiation heating could better protect cells from oxidative stress due to the higher SOD mimetic activity of the nanoparticles.

Modulation of surface structure and catalytic properties of cerium oxide nanoparticles by thermal and microwave synthesis techniques

International Nuclear Information System (INIS)

He, Jian; Zhou, Lan; Liu, Jie; Yang, Lu; Zou, Ling; Xiang, Junyu; Dong, Shiwu; Yang, Xiaochao

2017-01-01

Highlights: • The CNPs synthesized by microwave irradiation have more reactive hot spots than that synthesized by convective heating. • The CNPs synthesized by microwave irradiation exhibited higher SOD activity than that synthesized by convective heating. • The CNPs synthesized by microwave irradiation heating could better protect cells from oxidative stress. - Abstract: Cerium oxide nanoparticles (CNPs) have been intensively explored for biomedical applications in recent few years due to the versatile enzyme mimetic activities of the nanoparticles. However, the control of CNPs quality through the optimization of synthesis conditions remains largely unexplored as most of the previous studies only focus on utilizing the catalytic activities of the nanoparticles. In the present study, CNPs with size about 5 nm were synthesized by thermal decomposition method using traditional convective heating and recently developed microwave irradiation as heating source. The quality of CNPs synthesized by the two heating manner was evaluated. The CNPs synthesized by convective heating were slightly smaller than that synthesized by microwave irradiation heating. The cores of the CNPs synthesized by the two heating manner have similar crystal structure. While the surface subtle structures of the CNPs synthesized by two heating manner were different. The CNPs synthesized by microwave irradiation have more surface reactive hot spot than that synthesized by convective heating as the nanoparticles responded more actively to the redox environment variation. This difference resulted in the higher superoxide dismutase (SOD) mimetic activity of CNPs synthesized by microwave irradiation heating than that of the convective heating. Preliminary experiments indicated that the CNPs synthesized by microwave irradiation heating could better protect cells from oxidative stress due to the higher SOD mimetic activity of the nanoparticles.

Fluorescence, Decay Time, and Structural Change of Laser Dye Cresyl Violet in Solution due to Microwave Irradiation at GSM 900/1800 Mobile Phone Frequencies

Directory of Open Access Journals (Sweden)

Fuat Bayrakceken

2012-01-01

Full Text Available Microwave irradiation at GSM 900/1800 MHz mobile phone frequencies affects the electronic structure of cresyl violet in solution. These changes are important because laser-dye cresyl violet strongly bonds to DNA- and RNA-rich cell compounds in nerve tissues. The irradiation effects on the electronic structure of cresyl violet and its fluorescence data were all obtained experimentally at room temperature. For most laser dyes, this is not a trivial task because laser dye molecules possess a relatively complex structure. They usually consist of an extended system of conjugated double or aromatic π-bonds with attached auxochromic (electron donating groups shifting the absorption band further towards longer wavelength. Because of the intrinsically high degree of conjugation, the vibrational modes of the molecular units couple strongly with each other. We found that the fluorescence quantum yield was increased from to due to intramolecular energy hopping of cresyl violet in solution which is exposed to microwave irradiation at mobile phone frequencies, and the photonic product cannot be used as a laser dye anymore.

Morphological changes of nuclear and chromatin architecture after microwave electromagnetic field exposure in 3T3 fibroblast cell cultures

International Nuclear Information System (INIS)

Mircea, D.; Chirila, Lavinia; Ciurea, A. V.; Helm, G.; Hankins, G.; Redrick, Jan; Gavrila, L.; Sheppard, B.; Bloodgoog, R.; Pallin, I.; Nitu, Rozalia; Rusu, I.

2001-01-01

It is already demonstrated in the literature that electromagnetic fields, particularly the microwave irradiation could be a powerful weapon against human tumors , but also against human body itself, depending on the wave parameters and irradiation time. The effects of microwave electromagnetic fields on living systems were studied in detail all over the world and, furthermore, the potential of intracellular damages by cytoskeleton, nuclear, chromatin and DNA alterations were carefully evaluated. In this study, the authors emphasize the morphological changes of nucleus and chromatin in fibroblast cell line 3T3 after microwave exposure with progressive increasing powers and times of irradiation. It was used a pulsed wave with 915 MHz frequency, with forward power ranging between 3 - 10 W, emitted by a helical microwave antenna placed into the cell culture medium, close to the cell monolayer. The authors tried to define certain severity stages of nuclear material alterations following different wave intensities and to compare these effects with other cytoplasmic organelle alterations. It was found that the nuclear material is the most sensitive intracellular structure in microwave electromagnetic field exposure. Also the authors tried to establish a well-defined protocol of irradiation with microwave electromagnetic fields in order to destroy the microtubule system of cytoskeleton in different types of cellular lines, in vitro. The cytoskeleton structure was evaluated by immunofluorescence methods. In non-muscle cells the cytoskeleton stability is achieved by interaction between microtubule system and actin filaments. Microtubule depolymerization by microwave exposure produces a secondary instability of cytoskeleton, the actin filaments coupling and cell contractility. The increasing of fibroblast contractility allows a more efficient treatment of the wounds with low spontaneous healing. Electromagnetic therapy could be an alternative therapy in plastic surgery

One-step microwave synthesis of photoluminescent carbon nanoparticles from sodium dextran sulfate water solution

Science.gov (United States)

Kokorina, Alina A.; Goryacheva, Irina Y.; Sapelkin, Andrei V.; Sukhorukov, Gleb B.

2018-04-01

Photoluminescent (PL) carbon nanoparticles (CNPs) have been synthesized by one-step microwave irradiation from water solution of sodium dextran sulfate (DSS) as the sole carbon source. Microwave (MW) method is very simple and cheap and it provides fast synthesis of CNPs. We have varied synthesis time for obtaining high luminescent CNPs. The synthesized CNPs exhibit excitation-dependent photoluminescent. Final CNPs water solution has a blue- green luminescence. CNPs have low cytotoxicity, good photostability and can be potentially suitable candidates for bioimaging, analysis or analytical tests.

Pre-irradiation at a low dose-rate blunted p53 response

International Nuclear Information System (INIS)

Takahashi, Akihisa

2002-01-01

We investigated whether chronic irradiation at a low dose-rate interferes with the p53-centered signal transduction pathyway induced by radiation in human cultured cells and C57BL/6N mice. In in vitro experiments, we found that a challenge with X-ray irradiation immediately after chronic irradiation resulted in lower levels of p53 than those observed after the challenge alone in glioblastoma cells (A-172). In addition, the levels of p53-centered apoptosis and its related proteins after the challenge were strongly correlated with the above-mentioned phenomena in squamous cell carcinoma cells (SAS/neo). In in vivo experiments, the accumulation of p53 and Bax, and the induction of apoptosis were observed dose-dependently in mouse spleen at 12 h after a challenge with X-rays (3.0 Gy). However, we found significant suppression of p53 and Bax accumulation and the induction of apoptosis 12 h after challenge irradiation at 3.0 Gy with a high doses-rate following chronic pre-irradiation (1.5 Gy, 0.001 Gy/min). These findings suggest that chronic pre-irradiation suppressed the p53 function through radiation-induced signaling and/or p53 stability. (author)

Low-cost microwave radiometry for remote sensing of soil moisture

Science.gov (United States)

Chikando, Eric Ndjoukwe

2007-12-01

Remote sensing is now widely regarded as a dominant means of studying the Earth and its surrounding atmosphere. This science is based on blackbody theory, which states that all objects emit broadband electromagnetic radiation proportional to their temperature. This thermal emission is detectable by radiometers---highly sensitive receivers capable of measuring extremely low power radiation across a continuum of frequencies. In the particular case of a soil surface, one important parameter affecting the emitted radiation is the amount of water content or, soil moisture. A high degree of precision is required when estimating soil moisture in order to yield accurate forecasting of precipitations and short-term climate variability such as storms and hurricanes. Rapid progress within the remote sensing community in tackling current limitations necessitates an awareness of the general public towards the benefits of the science. Information about remote sensing instrumentation and techniques remain inaccessible to many higher-education institutions due to the high cost of instrumentation and the current general inaccessibility of the science. In an effort to draw more talent within the field, more affordable and reliable scientific instrumentation are needed. This dissertation introduces the first low-cost handheld microwave instrumentation fully capable of surface soil moisture studies. The framework of this research is two-fold. First, the development of a low-cost handheld microwave radiometer using the well-known Dicke configuration is examined. The instrument features a super-heterodyne architecture and is designed following a microwave integrated circuit (MIC) system approach. Validation of the instrument is performed by applying it to various soil targets and comparing measurement results to gravimetric technique measured data; a proven scientific method for determining volumetric soil moisture content. Second, the development of a fully functional receiver RF front

Poly(4-vinylphenol gate insulator with cross-linking using a rapid low-power microwave induction heating scheme for organic thin-film-transistors

Directory of Open Access Journals (Sweden)

Ching-Lin Fan

2016-03-01

Full Text Available A Microwave-Induction Heating (MIH scheme is proposed for the poly(4-vinylphenol (PVP gate insulator cross-linking process to replace the traditional oven heating cross-linking process. The cross-linking time is significantly decreased from 1 h to 5 min by heating the metal below the PVP layer using microwave irradiation. The necessary microwave power was substantially reduced to about 50 W by decreasing the chamber pressure. The MIH scheme is a good candidate to replace traditional thermal heating for cross-linking of PVP as the gate insulator for organic thin-film-transistors.

Thermal characteristics analysis of microwaves reactor for pyrolysis of used cooking oil

Science.gov (United States)

Anis, Samsudin; Shahadati, Laily; Sumbodo, Wirawan; Wahyudi

2017-03-01

The research is objected to develop microwave reactor for pyrolysis of used cooking oil. The effect of microwave power as well as addition of char as absorber towards its thermal characteristic were investigated. Domestic microwave was modified and used to test the thermal characteristic of used cooking oil in the terms of temperature evolution, heating rate, and thermal efficiency. The samples were examined under various microwave power of 347W, 399W, 572W and 642W for 25 minutes of irradiation time. The char loading was tested in the level of 0, 50, and 100 g. Microwave reactor consists of microwave unit with a maximum power of 642W, a ceramic reactor, and a condenser equipped with temperature measurement system was successfully developed. It was found that microwave power and addition of absorber significantly influenced the thermal characteristic of microwave reactor. Under investigated condition, the optimum result was obtained at microwave power of 642W and 100 g of char. The condition was able to provide temperature of 480°C, heating rate of 18.2°C/min and thermal efficiency of 53% that is suitable to pyrolyze used cooking oil.

Application of microwave heating to a polyesterification plant

NARCIS (Netherlands)

Komorowska-Durka, M.

2015-01-01

Utilizing microwave irradiation, a fundamentally different method of the energy transfer, to the chemical process units can potentially be advantageous compared to the conventional heating, inter alia due to the selective nature of interaction of the microwaves with the matter. This doctoral

Structural level set inversion for microwave breast screening

International Nuclear Information System (INIS)

Irishina, Natalia; Álvarez, Diego; Dorn, Oliver; Moscoso, Miguel

2010-01-01

We present a new inversion strategy for the early detection of breast cancer from microwave data which is based on a new multiphase level set technique. This novel structural inversion method uses a modification of the color level set technique adapted to the specific situation of structural breast imaging taking into account the high complexity of the breast tissue. We only use data of a few microwave frequencies for detecting the tumors hidden in this complex structure. Three level set functions are employed for describing four different types of breast tissue, where each of these four regions is allowed to have a complicated topology and to have an interior structure which needs to be estimated from the data simultaneously with the region interfaces. The algorithm consists of several stages of increasing complexity. In each stage more details about the anatomical structure of the breast interior is incorporated into the inversion model. The synthetic breast models which are used for creating simulated data are based on real MRI images of the breast and are therefore quite realistic. Our results demonstrate the potential and feasibility of the proposed level set technique for detecting, locating and characterizing a small tumor in its early stage of development embedded in such a realistic breast model. Both the data acquisition simulation and the inversion are carried out in 2D

Chemistry of the Enaminone of 1-Acetylnaphthalene under Microwave Irradiation Using Chitosan as a Green Catalyst

Directory of Open Access Journals (Sweden)

Huwaida M. E. Hassaneen

2011-01-01

Full Text Available Enaminone 1 was reacted with hydrazonoyl halides 2a-d to yield 3,4-disubstituted pyrazoles 6a-d. Coupling with arenediazonium chlorides afforded the 2-(arylhydrazono-3-(1-naphthalenyl-3-oxopropionaldehydes 13a-c. Compounds 13 could be utilized for the synthesis of a variety of arylpyrazoles, arylazolopyrimidines, and pyridazinones via reaction with hydrazines, aminoazoles, and active methylene derivatives, respectively. A comparative study of aforementioned reactions was carried out with chitosan as a basic ecofriendly catalyst under conventional heating as well as under pressurized microwave irradiation conditions.

Microwave Enhanced Cotunneling in SET Transistors

DEFF Research Database (Denmark)

Manscher, Martin; Savolainen, M.; Mygind, Jesper

2003-01-01

Cotunneling in single electron tunneling (SET) devices is an error process which may severely limit their electronic and metrologic applications. Here is presented an experimental investigation of the theory for adiabatic enhancement of cotunneling by coherent microwaves. Cotunneling in SET...... transistors has been measured as function of temperature, gate voltage, frequency, and applied microwave power. At low temperatures and applied power levels, including also sequential tunneling, the results can be made consistent with theory using the unknown damping in the microwave line as the only free...

Microwave-assisted facile and rapid Friedel-Crafts benzoylation of arenes catalysed by bismuth trifluoromethanesulfonate

DEFF Research Database (Denmark)

Tran, Phoung Hoang; Hansen, Poul Erik; Pham, Thuy Than

2014-01-01

The catalytic activity of metal triflates was investigated in Friedel–Crafts benzoylation under microwave irradiation. Friedel–Crafts benzoylation with benzoyl chloride of a variety of arenes containing electron-rich and electron-poor rings using bismuth triflate under microwave irradiation is de...

Direct transesterification of wet Cryptococcus curvatus cells to biodiesel through use of microwave irradiation

International Nuclear Information System (INIS)

Cui, Yi; Liang, Yanna

2014-01-01

Highlights: • Direct transesterfication of wet yeast cells using methanol and microwave irradiation is feasible. • Methanol to biomass ratio, stirring speed and KOH concentration were critical to biodiesel yield. • Under optimal conditions, the crude biodiesel contained 64% of FAMEs and was 92% of yeast lipids. - Abstract: Cryptococcus curvatus is a highly promising oleaginous yeast strain that can accumulate intracellular lipids when grown on renewable carbon sources. In order to convert yeast lipids to biodiesel in a simple but cost-effective way, we aim to react whole yeast cells with methanol to produce biodiesel eliminating the step of drying and lipid extraction while adopting microwave energy for heating and disrupting cell walls. Through use of a screening test followed by response surface methodology, optimal parameters leading to the highest yield of crude biodiesel and FAMEs were identified. Under optimal conditions of reaction time (2 min), methanol/biomass ratio (50/1, v/m), stirring speed (966 rpm), KOH concentration (5%), and water content (80%), the yield of crude biodiesel (% of total lipids) was 56.1% after the first round reaction. A second round reaction using the residual yeast cells increased the total yield to 92%. Among the crude biodiesel, 63.88% was FAMEs as revealed by GC analysis. Results from this study indicated that it is feasible to produce biodiesel from wet microbial biomass directly without the steps of drying and lipid extraction. With the assistance of microwave, this process can be accomplished in minutes with good process efficiency

Microwave Effect for Glycosylation Promoted by Solid Super Acid in Supercritical Carbon Dioxide

Directory of Open Access Journals (Sweden)

Takahiko Maeda

2009-12-01

Full Text Available The effects of microwave irradiation (2.45 GHz, 200 W on glycosylation promoted by a solid super acid in supercritical carbon dioxide was investigated with particular attention paid to the structure of the acceptor substrate. Because of the symmetrical structure and high diffusive property of supercritical carbon dioxide, microwave irradiation did not alter the temperature of the reaction solution, but enhanced reaction yield when aliphatic acceptors are employed. Interestingly, the use of a phenolic acceptor under the same reaction conditions did not show these promoting effects due to microwave irradiation. In the case of aliphatic diol acceptors, the yield seemed to be dependent on the symmetrical properties of the acceptors. The results suggest that microwave irradiation do not affect the reactivity of the donor nor promoter independently. We conclude that the effect of acceptor structure on glycosylation yield is due to electric delocalization of hydroxyl group and dielectrically symmetric structure of whole molecule.

Impacts of microwave pretreatments on the semi-continuous anaerobic digestion of dairy waste activated sludge

International Nuclear Information System (INIS)

Uma Rani, R.; Adish Kumar, S.; Kaliappan, S.; Yeom, IckTae; Rajesh Banu, J.

2013-01-01

Highlights: ► Microwave pretreatment of dairy WAS was studied. ► MW pretreatment at 70% intensity for 12 min, COD solubilization was 18.6%. ► Biogas production and SS reduction was 35% and 14% higher than control. ► In digester at 15 days SRT with medium OLR, SS and VS reduction was 67% and 64%. ► Biogas and methane production was 57% and 49% higher than control, in digesters. - Abstract: Microwave (MW) irradiation is one of the new and possible methods used for pretreating the sludge. Following its use in different fields, this MW irradiation method has proved to be more appropriate in the field of environmental research. In this paper, we focused on the effects of MW irradiation at different intensities on solubilization, biodegradation and anaerobic digestion of sludge from the dairy sludge. The changes in the soluble fractions of the organic matter, the biogas yield, the methane content in the biogas were used as control parameters for evaluating the efficiency of the MW pretreatment. Additionally, the energetic efficiency was also examined. In terms of an energetic aspect, the most economical pretreatment of sludge was at 70% intensity for 12 min irradiation time. At this, COD solubilization, SS reduction and biogas production were found to be 18.6%, 14% and 35% higher than the control, respectively. Not only the increase in biogas production was investigated, excluding protein and carbohydrate hydrolysis was also performed successfully by this microwave pretreatment even at low irradiation energy input. Also, experiments were carried out in semi continuous anaerobic digesters, with 3.5 L working volume. Combining microwave pretreatment with anaerobic digestion led to 67%, 64% and 57% of SS reduction, VS reduction and biogas production higher than the control, respectively

Effect of thermal treatments on the chemical and biological value of irradiated and non-irradiated cowpea bean (Vigna unguiculata L. Walp) flour

International Nuclear Information System (INIS)

Dario, A.C.; Salgado, J.M.

1994-01-01

Chemical and nutritional characteristics of irradiated and nonirradiated cowpea bean at 0.2 kGy submitted to several thermal treatments were studied. The cowpea bean flours irradiated at 0.2 kGy were superior to those non-irradiated concerning digestibility and the flours submitted to microwave oven were superior to those cooked under low pressure, autoclaved or even raw from the nutritional point of view. As to the presence of anti-nutritional factors, the results showed that the variety of cowpea bean under research presented neither trypsin inhibitor nor haemagglutinin activity, however, regarding tannin, a 0.006% content was found and considered negligible

The effects of illumination on deep levels observed in as-grown and low-energy electron irradiated high-purity semi-insulating 4H-SiC

Science.gov (United States)

Alfieri, G.; Knoll, L.; Kranz, L.; Sundaramoorthy, V.

2018-05-01

High-purity semi-insulating 4H-SiC can find a variety of applications, ranging from power electronics to quantum computing applications. However, data on the electronic properties of deep levels in this material are scarce. For this reason, we present a deep level transient spectroscopy study on HPSI 4H-SiC substrates, both as-grown and irradiated with low-energy electrons (to displace only C-atoms). Our investigation reveals the presence of four deep levels with activation energies in the 0.4-0.9 eV range. The concentrations of three of these levels increase by at least one order of magnitude after irradiation. Furthermore, we analyzed the behavior of these traps under sub- and above-band gap illumination. The nature of the traps is discussed in the light of the present data and results reported in the literature.

Microwave Absorption Characteristics of Tire

Science.gov (United States)

Zhang, Yuzhe; Hwang, Jiann-Yang; Peng, Zhiwei; Andriese, Matthew; Li, Bowen; Huang, Xiaodi; Wang, Xinli

The recycling of waste tires has been a big environmental problem. About 280 million waste tires are produced annually in the United States and more than 2 billion tires are stockpiled, which cause fire hazards and health issues. Tire rubbers are insoluble elastic high polymer materials. They are not biodegradable and may take hundreds of years to decompose in the natural environment. Microwave irradiation can be a thermal processing method for the decomposition of tire rubbers. In this study, the microwave absorption properties of waste tire at various temperatures are characterized to determine the conditions favorable for the microwave heating of waste tires.

A novel and efficient method for the immobilization of thermolysin using sodium chloride salting-in and consecutive microwave irradiation.

Science.gov (United States)

Chen, Feifei; Zhang, Fangkai; Du, Fangchuan; Wang, Anming; Gao, Weifang; Wang, Qiuyan; Yin, Xiaopu; Xie, Tian

2012-07-01

Sodium chloride salting-in and microwave irradiation were combined to drive thermolysin molecules into mesoporous support to obtain efficiently immobilized enzyme. When the concentration of sodium chloride was 3 M and microwave power was 40 W, 93.2% of the enzyme was coupled to the support by 3 min, and the maximum specific activity of the immobilized enzyme was 17,925.1 U mg(-1). This was a 4.5-fold increase in activity versus enzyme immobilized using conventional techniques, and a 1.6-fold increase versus free enzyme. Additionally, the thermal stability of the immobilized thermolysin was significantly improved. When incubated at 70°C, there was no reduction in activity by 3.5h, whereas free thermolysin lost most of its activity by 3h. Immobilization also protected the thermolysin against organic solvent denaturation. The microwave-assisted immobilization technique, combined with sodium chloride salting-in, could be applied to other sparsely soluble enzymes immobilization because of its simplicity and high efficiency. Copyright © 2011 Elsevier Ltd. All rights reserved.

ITO thin films prepared by a microwave heating

International Nuclear Information System (INIS)

Okuya, Masayuki; Ito, Nobuyuki; Shiozaki, Katsuyuki

2007-01-01

ITO thin films were prepared by irradiating 2.45 GHz of microwave with an output power of 700 W using a commercial kitchen microwave oven. A substrate temperature went up and down rapidly between 100 and 650 deg. C in a minute by a dielectric loss of SnO 2 layer pre-deposited on a glass substrate. We found that the electrical and optical properties of films were affected by the atmosphere in a microwave irradiation, while the sintering was completed within a few minutes. Although the electrical resistivity was not reduced below 5.0 x 10 -4 Ω.cm in this study, the results lead to the possibility of a practical rapid synthesis of ITO transparent conducting oxide films

A Review of Microwave-Assisted Reactions for Biodiesel Production

Directory of Open Access Journals (Sweden)

Saifuddin Nomanbhay

2017-06-01

Full Text Available The conversion of biomass into chemicals and biofuels is an active research area as trends move to replace fossil fuels with renewable resources due to society’s increased concern towards sustainability. In this context, microwave processing has emerged as a tool in organic synthesis and plays an important role in developing a more sustainable world. Integration of processing methods with microwave irradiation has resulted in a great reduction in the time required for many processes, while the reaction efficiencies have been increased markedly. Microwave processing produces a higher yield with a cleaner profile in comparison to other methods. The microwave processing is reported to be a better heating method than the conventional methods due to its unique thermal and non-thermal effects. This paper provides an insight into the theoretical aspects of microwave irradiation practices and highlights the importance of microwave processing. The potential of the microwave technology to accomplish superior outcomes over the conventional methods in biodiesel production is presented. A green process for biodiesel production using a non-catalytic method is still new and very costly because of the supercritical condition requirement. Hence, non-catalytic biodiesel conversion under ambient pressure using microwave technology must be developed, as the energy utilization for microwave-based biodiesel synthesis is reported to be lower and cost-effective.

Development of low-power loss Mn–Zn ferrites using microwave ...

Indian Academy of Sciences (India)

Unknown

sinusoidal voltage of 25 V with frequency, 1 MHz. The efficiency and surface rise of temperature of trans- former were found to be high and low, respectively. Keywords. Ferrites; microwave sintering; conventional sintering; power loss; hysteresis loss; eddy current loss; transformer; high frequency applications. 1. Introduction.

Long-term microwaving of denture base materials: effects on dimensional, color and translucency stability

Directory of Open Access Journals (Sweden)

Nick POLYCHRONAKIS

2018-06-01

Full Text Available Abstract While the combined effect of microwave irradiation with cleansing solutions on denture base materials has been investigated, the effects of only using microwave irradiation and, more importantly, in a long-term basis, was not studied yet. Objective The purpose of this study was to evaluate the effect of a long-term repeated microwaving on the dimensional, color and translucency stability of acrylic and polyamide denture base materials. Material and Methods Thirty two specimens (32 mm x 10 mm x 2.5 mm from polyamide (Valplast and PMMA (Vertex Rapid Simplified denture base materials were made. Eight specimens from each material were immersed in distilled water (control and 8 were subjected to microwave exposure at 450 W for 3 minutes for a period simulating 224 days of daily disinfection. Linear dimension, color change (ΔE* and translucency parameter (TP were measured at baseline and after certain intervals up to 224 cycles of immersion, using a digital calliper and a portable colorimeter. The results were analysed using two-way repeated measures ANOVA to estimate possible differences among predetermined cycles and material type. Regression analysis was also performed to estimate the trend of changes with time. Statistical evaluations performed at a significance level of 5%. Results Data analysis showed significant changes in length at baseline with an increasing number of cycles (p0.05. TP decreased similarly in both materials following microwave action but in a significantly higher level for Valplast (p<0.001. Conclusions The results indicated that long-term repeated microwaving affects linear dimensional, color and translucency changes of both materials. Differences between PMMA and polyamide material were noted only in dimension and translucency changes.

Microwave heating in solid-phase peptide synthesis

DEFF Research Database (Denmark)

Pedersen, Søren Ljungberg; Shelton, Anne Pernille Tofteng; Malik, Leila

2012-01-01

synthesis, precise microwave irradiation to heat the reaction mixture during coupling and N(a)-deprotection has become increasingly popular. It has often provided dramatic reductions in synthesis times, accompanied by an increase in the crude peptide purity. Microwave heating has been proven especially...... relevant for sequences which might form ß-sheet type structures and for sterically difficult couplings. The beneficial effect of microwave heating appears so far to be due to the precise nature of this type of heating, rather than a peptide-specific microwave effect. However, microwave heating...... in microwave heating for peptide synthesis, with a focus on systematic studies and general protocols, as well as important applications. The assembly of ß-peptides, peptoids and pseudopeptides are also evaluated in this critical review (254 references)....

The microwave absorbing properties of ZnO/Fe3O4/paraffin composites in low frequency band

Science.gov (United States)

Yin, Pengfei; Deng, Yu; Zhang, Limin; Huang, Juan; Li, Huayao; Li, Youhongyu; Qi, Yali; Tao, Yu

2018-02-01

ZnO/Fe3O4/paraffin composites with good microwave absorption performance in low frequency band were prepared by physical blending technology. The morphology, phase structures, frequency-dependent electromagnetic and microwave absorbing properties of the composites were investigated. The results showed that the addition content of ZnO can adjust the microwave absorbing properties i.e. the position, intensity, and absorption bandwidth of composites, and the synergetic consequence of dielectric loss and magnetic loss is the main microwave absorption mechanism of the composites. The bandwidths with RL below -10 dB over different frequency ranges were obtained in the low frequency range of 0.5 ˜ 3 GHz at a thickness of 5 mm, e.g. 0.93 GHz from 1.59 to 2.52 GHz and 0.85 GHz from 1.26 to 2.11 GHz corresponding to the mass ratios of ZnO and Fe3O4 are 1:2 and 1:4, respectively. Thus, such absorbers can be applied as effective microwave absorbers in low frequency range of 0.5 ˜ 3 GHz.

Genetic efficiency of low-dose chronic irradiation in mammals and fish

International Nuclear Information System (INIS)

Goncharova, R.; Ryabokon, N.; Smolich, I.; Slukvin, A.

2001-01-01

The problem of biological effects of low-dose chronic irradiation is central radiobiological problem and seems to be very important for human monitoring and risk assessment Since 1986 we are engaged in studying genetic effects of low-dose chronic irradiation in natural populations of small mammals (bank vole - Clethrioiiomys glareolus) inhabiting radiocontaminated monitoring sites, in laboratory hybrid mice CBA*C57BI/6 j exposed to chronic irradiation at radiocontaminated sites, as well as in pond carp (Cyprinus carpio) reared in fish farms in areas contaminated due to the Chernobyl accident. The mean ground depositions in monitoring sites were 8-2330 kBq/m 2 and the mean bottom depositions in ponds were 52-3235 Bq/kg for Cs 137. We used conventional cytogenetics and genetics tests [1-3] and the following approaches in studying on genetic effects of low-dose chronic irradiation: Radiation exposures from external γ- and internal α, β, γ-irradiation from incorporated radionuclides were estimated for each specimen tested. Regression analysis of dose-effect relationships based on comparison of individual genetic end-points with individual absorbed doses was carried out We observed statistically significant changes in the frequencies of genetic end-points, which have been studied in somatic and germ cells, as well as in embryos of irradiated mammals and fish. So, the frequencies of chromosome aberrations in bank vole populations had up to 7-fold increase in comparison with background and pre-accident levels. It is of great importance to emphasize high radio-sensitivity of fertilized eggs (zygotes) and pond carp, embryos produced by chronically irradiated parents. Regression analysis allowed to reveal dependence of the studied parameters' frequencies on radiation exposure namely on the concentrations of basic dose forming radionuclides, absorbed dose rate and whole body absorbed dose. In most cases, dose-effect relationships were better approximated by non

Microwave-assisted Maillard reactions for the preparation of advanced glycation end products (AGEs).

Science.gov (United States)

Visentin, Sonja; Medana, Claudio; Barge, Alessandro; Giancotti, Valeria; Cravotto, Giancarlo

2010-05-21

The application of microwaves as an efficient form of volumetric heating to promote organic reactions was recognized in the mid-1980 s. It has a much longer history in the food research and industry where microwave irradiation was studied in depth to optimize food browning and the development of desirable flavours from Maillard reactions. The microwave-promoted Maillard reaction is a challenging synthetic method to generate molecular diversity in a straightforward way. In this paper we present a new rapid and efficient one-pot procedure for the preparation of pentosidine and other AGEs under microwave irradiation.

The influence of low dose irradiation on intracellular pH level, synthesizing activity and ATP level in cultured chinese fibroblasts

International Nuclear Information System (INIS)

Parkhomenko, I.M.; Perishvili, G.V.; Turovetskij, V.B.; Kudryashov, Yu.B.; Rubin, A.B.; Brovko, L.Yu.

1993-01-01

X-irradiation of Chinese fibroblasts with doses of 0.05-0.15 Gy was shown to cause intracellular pH (pH i ) changes: its diminishing during the first 40-60 min by 0.16-0.18 pH units, then the return to the control level 120 min after irradiation and, finally, the increase by 0.18-0.20 pH units. Simultaneously, the synthesizing activity of the cells changed in the same way. The ATP level changed in the opposite way: increased when pH fell and decreased when pH grew. It was shown that pH i changes were connected with the changes in Na + /H + -exchange system, and they seemed to be primary in the chain of the alterations observed

[Level of microwave radiation from mobile phone base stations built in residential districts].

Science.gov (United States)

Hu, Ji; Lu, Yiyang; Zhang, Huacheng; Xie, Hebing; Yang, Xinwen

2009-11-01

To investigate the condition of microwave radiation pollution from mobile phone base station built in populated area. Random selected 18 residential districts where had base station and 10 residential districts where had no base stations. A TES-92 electromagnetic radiation monitor were used to measure the intensity of microwave radiation in external and internal living environment. The intensities of microwave radiation in the exposure residential districts were more higher than those of the control residential districts (p station, it would gradually weaken with the increase of the distance. The level of microwave radiation in antenna main lobe region is not certainly more higher than the side lobe direction, and the side lobe direction also is not more lower. At the same district, where there were two base stations, the electromagnetic field nestification would take place in someplace. The intensities of microwave radiation outside the exposure windows in the resident room not only changed with distance but also with the height of the floor. The intensities of microwave radiation inside the aluminum alloys security net were more lower than those of outside the aluminum alloys security net (p 0.05). Although all the measure dates on the ground around the base station could be below the primary standard in "environment electromagnetic wave hygienic standard" (GB9175-88), there were still a minorities of windows which exposed to the base station were higher, and the outside or inside of a few window was even higher beyond the primary safe level defined standard. The aluminum alloys security net can partly shield the microwave radiation from the mobile phone base station.

Low Dietary Protein Status Potentiating Risk of Health Hazard in Whole Body Gamma Irradiated Rats

International Nuclear Information System (INIS)

El-Gawish, M.A.M.; Yousri, R.M.; Roushdy, H.M.; Abdel-Reheem, K.A.; Al-Mossallamy, N.A.

1998-01-01

Investigations were planned to assess the changes in certain biochemical parameters as affected by the synergistic effect of exposure to fractionated doses of rays and / or feeding on different protein levels. The date showed that animals kept on normal or low protein diet exhibited a significant decrease in serum total protein and glucose. Also , a significant increase was recorded in insulin level in rats exposed at the radiation dose level of 20 Gy. Exposure to cumulative doses of irradiation has aggrevated the hyperglycemic effect of high protein diet with a significant and marked increase of insulin at all the applied doses. Animals fed normal high or low protein diet were found to exert significant decreases in T3, T4 while a significant increase in TSH of high protein group occurred as a result of exposure to cumulative doses of gamma-irradiation. Rats kept on low protein diet exhibited losses in body weight, hypercholesterolemia, low levels of phospholipids and triglycerides as compared with the normal protein diet group. In contrast high protein diet group showed no serious effects. Irradiation has potentiated body weight losses, hypotriglyceridemia and hypercholesterolemia in animal group fed low protein diet with a significant increase in serum phospholipids due to the higher radiation dose of 20 Gy. Protein deficiency acted synergistically with gamma irradiation and increased the susceptibility of body organs to radiation damage. Such findings contributed to the knowledge which stimulated the decrease of the internationally recognized occupational dose limits from 50 down to 20 m Sv (ICRP 1991)

Searching for concentric low variance circles in the cosmic microwave background

Energy Technology Data Exchange (ETDEWEB)

DeAbreu, Adam [Department of Physics, Simon Fraser University, Burnaby, BC, V5A 1S6 Canada (Canada); Contreras, Dagoberto; Scott, Douglas, E-mail: adeabreu@sfu.ca, E-mail: dagocont@phas.ubc.ca, E-mail: dscott@phas.ubc.ca [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1 Canada (Canada)

2015-12-01

In a recent paper, Gurzadyan and Penrose claim to have found directions in the sky around which there are multiple concentric sets of annuli with anomalously low variance in the cosmic microwave background (CMB). These features are presented as evidence for a particular theory of the pre-Big Bang Universe. We are able to reproduce the analysis these authors presented for data from the WMAP satellite and we confirm the existence of these apparently special directions in the newer Planck data. However, we also find that these features are present at the same level of abundance in simulated Gaussian CMB skies, i.e., they are entirely consistent with the predictions of the standard cosmological model.

Non-invasive determination of the irradiation dose in fingers using low-frequency EPR

International Nuclear Information System (INIS)

Zdravkova, M; Crokart, N; Trompier, F; Beghein, N; Gallez, B; Debuyst, R

2004-01-01

Several reports in the literature have described the effects of radiation in workers who exposed their fingers to intense radioactive sources. The radiation injuries occurring after local exposure to a high dose (20 to 100 Gy) could lead to the need for amputation. Follow-up of victims needs to be more rational with a precise knowledge of the irradiated area that risks tissue degradation and necrosis. It has been described previously that X-band electron paramagnetic resonance (EPR) spectroscopy could be used to assess the dose in irradiated amputated fingers. Here, we propose the use of low-frequency EPR spectroscopy to evaluate non-invasively the absorbed dose. Low-frequency microwaves are indeed less absorbed by water and penetrate more deeply into living material (∼10 mm in tissues using 1 GHz spectrometers). This work presents preliminary results obtained with baboon and human fingers compared with human dry phalanxes placed inside a surface-coil resonator. The EPR signal increased linearly with the dose. The ratio of the slopes of the dry bone to whole finger linear regression lines was around 5. The detection limit achievable with the present spectrometer and resonator is around 60 Gy, which is well within the range of accidentally exposed fingers. It is likely that the detection limit could be improved in the future, thanks to further technical spectrometer and resonator developments as well as to appropriate spectrum deconvolution into native and dosimetric signals

Microwave sintering of ceramic materials

Science.gov (United States)

Karayannis, V. G.

2016-11-01

In the present study, the potential of microwave irradiation as an innovative energy- efficient alternative to conventional heating technologies in ceramic manufacturing is reviewed, addressing the advantages/disadvantages, while also commenting on future applications of possible commercial interest. Ceramic materials have been extensively studied and used due to several advantages they exhibit. Sintering ceramics using microwave radiation, a novel technology widely employed in various fields, can be an efficient, economic and environmentally-friendlier approach, to improve the consolidation efficiency and reduce the processing cycle-time, in order to attain substantial energy and cost savings. Microwave sintering provides efficient internal heating, as energy is supplied directly and penetrates the material. Since energy transfer occurs at a molecular level, heat is generated throughout the material, thus avoiding significant temperature gradients between the surface and the interior, which are frequently encountered at high heating rates upon conventional sintering. Thus, rapid, volumetric and uniform heating of various raw materials and secondary resources for ceramic production is possible, with limited grain coarsening, leading to accelerated densification, and uniform and fine-grained microstructures, with enhanced mechanical performance. This is particularly important for manufacturing large-size ceramic products of quality, and also for specialty ceramic materials such as bioceramics and electroceramics. Critical parameters for the process optimization, including the electromagnetic field distribution, microwave-material interaction, heat transfer mechanisms and material transformations, should be taken into consideration.

Identification of irradiated oysters by EPR measurements on shells

Energy Technology Data Exchange (ETDEWEB)

Della Monaca, S., E-mail: sara.dellamonaca@iss.it [Istituto Superiore di Sanita, viale Regina Elena, 299 Rome (Italy); Fattibene, P.; Boniglia, C.; Gargiulo, R.; Bortolin, E. [Istituto Superiore di Sanita, viale Regina Elena, 299 Rome (Italy)

2011-09-15

In this paper the EPR spectra of the radicals induced in oyster shells after irradiation to (0.5-2) kGy ionizing radiation doses are analyzed. EPR spectra of irradiated shells showed the complex radical composition of biocarbonates, characterized by the presence of SO{sub 2}{sup -}, SO{sub 3}{sup -} and CO{sub 2}{sup -} radicals with different symmetries. In particular, the radiation-induced line at g = 2.0038, due to the g{sub x} component of the orthorhombic SO{sub 3}{sup -}, was well distinguishable from the rest of the spectrum. The g{sub x} component of the orthorhombic SO{sub 3}{sup -} was found to be intense and stable enough to allow the identification at least for the whole shelf life of the oyster. Furthermore, it is still well visible at low microwave powers for which the other signals are weak or non-visible and has a linear dose response in the (0.5-2) kGy range. A possible procedure protocol for the identification of irradiated oysters, can be based on acquisitions of the spectrum at low microwave power values (tenths of milliWatt) and low modulation amplitude values (0.03-0.05 mT) and on the identification of the g = 2.0038 signal as a proof of the ionizing radiation treatment performed on the sample.

Action of low-power laser irradiation on the proliferation of human gingival fibroblasts in vitro

Science.gov (United States)

Almeida-Lopes, Luciana; Jaeger, Marcia M. M.; Brugnera, Aldo, Jr.; Rigau, Josepa

1998-04-01

The low level power laser has been used in dental treatments aiming to improve tissue healing. An in vitro study was performed to analyze the laser influence on gingival fibroblast. A human gingival fibroblast culture (LMF) was produced in DME medium with 10% bovine fetal serum (BFS) cells (LMF) were allocated in Petri plates and cultured in different SFB concentrations (0%, 5% e 10%). After 48 hours the plates were divided in 9 groups: 3 control: 3 irradiated by 635 nm laser; and 3 irradiated by 780 nm laser. The cultured cells received 4 applications, in 12 hours intervals, with energy dosage of 2 joules for each plate, by means of a punctual technique. The growth curves showed that the growth levels were lower in low BFS concentrations. The irradiation with laser accelerated the growth rate in all groups. Additionally, the number of cells developed in low BFS concentration (5%) and irradiated was similar to the number of control cells developed in ideal conditions (10% BFS). There was no statistically significant differences between the effects of the two types of laser studied.

Development of shelf stable, processed, low acid food products using heat-irradiation combination treatments

International Nuclear Information System (INIS)

Minnaar, A.

1998-01-01

The amount of ionizing irradiation needed to sterilize low acid vegetable and starch products (with and without sauces) commercially impairs their sensorial and nutritive qualities, and use of thermal processes for the same purpose may also have an adverse effect on the product quality. A systematic approach to the establishment of optimized combination parameters was developed for heat-irradiation processing to produce high quality, shelf stable, low acid food products. The effects of selected heat, heat-irradiation combination and irradiation treatments on the quality of shelf stable mushrooms in brine and rice, stored at ambient temperature, were studied. From a quality viewpoint, use of heat-irradiation combination treatments favouring low irradiation dose levels offered a feasible alternative to thermally processed or radappertized mushrooms in brine. However, shelf stable rice produced by heat-irradiation combination treatments offered a feasible alternative only to radappertized rice from the standpoint of quality. The technical requirements for the heat and irradiation processing of a long grain rice cultivar from the United States of America oppose each other directly, thereby reducing the feasibility of using heat-irradiation combination processing to produce shelf stable rice. The stability of starch thickened white sauces was found to be affected severely during high dose irradiation and subsequent storage at ambient temperature. However, use of pea protein isolate as a thickener in white sauces was found to have the potential to maintain the viscosity of sauces for irradiated meat and sauce products throughout processing and storage. (author)

Microwave Induced Welding of Carbon Nanotube-Thermoplastic Interfaces for Enhanced Mechanical Strength of 3D Printed Parts

Science.gov (United States)

Sweeney, Charles; Lackey, Blake; Saed, Mohammad; Green, Micah

Three-dimensional (3D) printed parts produced by fused-filament fabrication of a thermoplastic polymer have become increasingly popular at both the commercial and consumer level. The mechanical integrity of these rapid-prototyped parts however, is severely limited by the interfillament bond strength between adjacent extruded layers. In this report we propose for the first time a method for welding thermoplastic interfaces of 3D printed parts using the extreme heating response of carbon nanotubes (CNTs) to microwave energy. To achieve this, we developed a coaxial printer filament with a pure polylactide (PLA) core and a CNT composite sheath. This produces parts with a thin electrically percolating network of CNTs at the interfaces between adjacent extruded layers. These interfaces are then welded together upon microwave irradiation at 2.45GHz. Our patent-pending method has been shown to increase the tensile toughness by 1000% and tensile strength by 35%. We investigated the dielectric properties of the PLA/CNT composites at microwave frequencies and performed in-situ microwave thermometry using a forward-looking infrared (FLIR) camera to characterize the heating response of the PLA/CNT composites upon microwave irradiation.

Hippocampal development in the rat: cytogenesis and morphogenesis examined with autoradiography and low-level x-irradiation

International Nuclear Information System (INIS)

Bayer, S.A.; Altman, J.

1974-01-01

The cytogenesis and morphogenesis of the rat hippocampus was examined with the techniques of 3 H-thymidine autoradiography, cell pyknosis produced by low-level x-irradiation, and quantitative histology. The procedure of progressively delayed cumulative labelling was used for autoradiography. Groups of rats were injected with four successive daily doses of 3 H-thymidine during non-overlapping periods ranging from birth to day 19. They were killed at 60 days of age, and the percentage of labelled cells was determined. Cell pyknosis in Ammon's horn reaches a maximal level prenatally and declines rapidly during the early postnatal period. Cell pyknosis in the dentate gyrus reaches its highest level during the second postnatal week and declines gradually with some radiosensitive cells still present in the adult. Immature granule cells are also at their highest level during the second postnatal week, while mature granule cells gradually accumulate to attain asymptotic levels at around two months of age. The alignment of the pyramidal cells to form the characteristic curvature of Ammon's horn occurs shortly after pyramidal cell cytogenesis is completed. Mechanisms for the morphological development of the dentate gyrus along with a consideration of the possible migratory route of granule cell precursors are discussed. (U.S.)

Process intensification of biodiesel production by using microwave and ionic liquids as catalyst

International Nuclear Information System (INIS)

Handayani, Prima Astuti; Abdullah; Hadiyanto, Dan

2015-01-01

The energy crisis pushes the development and intensification of biodiesel production process. Biodiesel is produced by transesterification of vegetable oils or animal fats and conventionally produced by using acid/base catalyst. However, the conventional method requires longer processing time and obtains lower yield of biodiesel. The microwave has been intensively used to accelerate production process and ionic liquids has been introduced as source of catalyst. This paper discusses the overview of the development of biodiesel production through innovation using microwave irradiation and ionic liquids catalyst to increase the yield of biodiesel. The potential microwave to reduce the processing time will be discussed and compared with other energy power, while the ionic liquids as a new generation of catalysts in the chemical industry will be also discussed for its use. The ionic liquids has potential to enhance the economic and environmental aspects because it has a low corrosion effect, can be recycled, and low waste form

Process intensification of biodiesel production by using microwave and ionic liquids as catalyst

Energy Technology Data Exchange (ETDEWEB)

Handayani, Prima Astuti [Department of Chemical Engineering, Diponegoro University (Indonesia); Chemical Engineering Program, Faculty of Engineering, Semarang State University (Indonesia); Abdullah; Hadiyanto, Dan, E-mail: hadiyanto@live.undip.ac.id [Department of Chemical Engineering, Diponegoro University (Indonesia)

2015-12-29

The energy crisis pushes the development and intensification of biodiesel production process. Biodiesel is produced by transesterification of vegetable oils or animal fats and conventionally produced by using acid/base catalyst. However, the conventional method requires longer processing time and obtains lower yield of biodiesel. The microwave has been intensively used to accelerate production process and ionic liquids has been introduced as source of catalyst. This paper discusses the overview of the development of biodiesel production through innovation using microwave irradiation and ionic liquids catalyst to increase the yield of biodiesel. The potential microwave to reduce the processing time will be discussed and compared with other energy power, while the ionic liquids as a new generation of catalysts in the chemical industry will be also discussed for its use. The ionic liquids has potential to enhance the economic and environmental aspects because it has a low corrosion effect, can be recycled, and low waste form.

Alteration of cellular and subcellular electrophysiological parameters in mammalian cells by high- and low-LET irradiation at low dose-levels. Part of a coordinated programme on cell membrane probes as biological indicators in radiation accidents

International Nuclear Information System (INIS)

Pohl-Rueling, J.

1980-12-01

The transmembrane resting potential (MRP) was chosen as a highly sensitive indicator for cellular reactions. The MRP was studied for its suitability as biological indicator of the level of accidental radiation exposure. The development of methodology and installation of a low-cost test chamber, and dose-response studies of MRP-changes of human cells after irradiation with low- and high-LET radiation were considered. Cultured human embryonic lung fibroblasts and human lung biopsy samples were used, with a Co-60 source for low-LET irradiation at dose rates of 2 rad and 20 rad/min, respectively. For high-LET irradiation an Am-241 source was used. The onset of radiation induced effects on cell membranes was prompt but of short duration. In general, full recovery followed within hours of irradiation, at least under the particular experimental conditions. MRP changes in irradiated cells proved a highly sensitive parameter for assessing radiation effects on cell membranes. It appears premature to draw conclusions on the suitability of the method as a biological indicator of radiation damage from accidental exposure, in view of the short duration and prompt reversibility of the effects, and an incomplete understanding of the radiation-induced reactions involved at different LET's and at different doses and dose-rates

Preparation and study of tramadol imprinted micro-and nanoparticles by precipitation polymerization: microwave irradiation and conventional heating method.

Science.gov (United States)

Seifi, Mahmoud; Hassanpour Moghadam, Maryam; Hadizadeh, Farzin; Ali-Asgari, Safa; Aboli, Jafar; Mohajeri, Seyed Ahmad

2014-08-25

In the present work a series of tramadole imprinted micro- and nanoparticles were prepared and study their recognition properties. Methacrylic acid (MAA), as a functional monomer, ethylene glycol dimethacrylate (EGDMA) as a cross-linker and different solvents (chloroform, toluene and acetonitrile (ACN)) were used for the preparation of molecularly imprinted polymers (MIPs) and non-imprinted polymers (NIPs). Several factors such as template/monomer molar ratio, volume of polymerization solvent, total monomers/solvent volume ratio, polymerization condition (heating or microwave irradiation) were also investigated. Particle size of the polymers, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), rebinding, selectivity tests and release study were applied for evaluation of the polymers. The optimized polymers with smaller particle size and superior binding properties were obtained in acetonitrile under heating method. MIPA4 with a size of 42.6 nm and a binding factor (BF) of 6.79 was selected for selectivity and release tests. The polymerization was not successful in acetonitrile and toluene under microwave irradiation. The MIPA4 could selectively adsorb tramadol, compared to imipramine, naltrexone and gabapentin. The data showed that tramadol release from MIPA4 was significantly slower than that of its non-imprinted polymer. Therefore, MIP nanoparticles with high selectivity, binding capacity and ability to control tramadol release could be obtained in precipitation polymerization with optimized condition. Copyright © 2014 Elsevier B.V. All rights reserved.

Stimulation of seeds by low dose irradiation

International Nuclear Information System (INIS)

Lawson, Helen

1976-05-01

The first section of the bibliography lists materials on the stimulation of seeds by low dose irradiation, with particular reference to stimulation of germination and yield. The second section contains a small number of selected references on seed irradiation facilities. (author)

Primary, Secondary Metabolites, H2O2, Malondialdehyde and Photosynthetic Responses of Orthosiphon stimaneus Benth. to Different Irradiance Levels

Directory of Open Access Journals (Sweden)

Mohd Hafiz Ibrahim

2012-01-01

Full Text Available The resource availability hypothesis predicts an increase in the allocation to secondary metabolites when carbon gain is improved relative to nutrient availability, which normally occurs during periods of low irradiance. The present work was carried out to confirm this hypothesis by investigating the effects of decreasing irradiance on the production of plant secondary metabolites (flavonoids and phenolics in the herbal plant Orthosiphon stamineus, and to characterize this production by carbohydrate, H2O2, and malondialdehyde (MDA levels, net photosynthesis, leaf chlorophyll content and carbon to nitrogen ratio (C/N. Four levels of irradiance (225, 500, 625 and 900 µmol/m2/s were imposed onto two-week old seedlings for 12 weeks in a randomized complete block design experiment. Peak production of total flavonoids, phenolics, soluble sugar, starch and total non-structural carbohydrate ocurred under low irradiance of 225 µmol/m2/s, and decreased with increasing irradiance. The up-regulation of secondary metabolites could be explained by the concomitant increases in H2O2 and MDA activities under low irradiance. This condition also resulted in enhanced C/N ratio signifying a reduction in nitrogen levels, which had established significant negative correlations with net photosynthesis, total biomass and total chlorophyll content, indicating the possible existence of a trade-off between growth and secondary metabolism under low irradiance with reduced nitrogen content. The competition between total chlorophyll and secondary metabolites production, as exhibited by the negative correlation coefficient under low irradiance, also suggests a sign of gradual switch of investment from chlorophyll to polyphenols production.

Preparation and characterization of activated carbon from pistachio nut shells via microwave-induced chemical activation

Energy Technology Data Exchange (ETDEWEB)

Foo, K. Y. [School of Chemical Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); Hameed, B.H., E-mail: chbassim@eng.usm.my [School of Chemical Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia)

2011-07-15

In this work, pistachio nut shell, a biomass residue abundantly available from the pistachio nut processing industries, was utilized as a feedstock for the preparation of activated carbon (PSAC) via microwave assisted KOH activation. The activation step was performed at the microwave input power of 600 W and irradiation time of 7 min. The porosity, functional and surface chemistry were featured by means of low temperature nitrogen adsorption, scanning electron microscopy and Fourier transform infrared spectroscopy. Result showed that the BET surface area, Langmuir surface area, and total pore volume of PSAC were 700.53 m{sup 2} g{sup -1}, 1038.78 m{sup 2} g{sup -1} and 0.375 m{sup 3} g{sup -1}, respectively. The adsorptive property of PSAC was tested using methylene blue dye as the targeted adsorbate. Equilibrium data was best fitted by the Langmuir isotherm model, showing a monolayer adsorption capacity of 296.57 mg g{sup -1}. The study revealed the potentiality of microwave-induced activation as a viable activation method. -- Highlights: {yields} Pistachio nut shell activated carbon (PSAC) was prepared via microwave assisted KOH activation. {yields} The activation step was performed at the microwave input power of 600 W and irradiation time of 7 min. {yields} BET surface area of PSAC was 700.53 m{sup 2}/g. {yields} Monolayer adsorption capacity of PSAC for MB was 296.57 mg/g.

Preparation and characterization of activated carbon from pistachio nut shells via microwave-induced chemical activation

International Nuclear Information System (INIS)

Foo, K.Y.; Hameed, B.H.

2011-01-01

In this work, pistachio nut shell, a biomass residue abundantly available from the pistachio nut processing industries, was utilized as a feedstock for the preparation of activated carbon (PSAC) via microwave assisted KOH activation. The activation step was performed at the microwave input power of 600 W and irradiation time of 7 min. The porosity, functional and surface chemistry were featured by means of low temperature nitrogen adsorption, scanning electron microscopy and Fourier transform infrared spectroscopy. Result showed that the BET surface area, Langmuir surface area, and total pore volume of PSAC were 700.53 m 2 g -1 , 1038.78 m 2 g -1 and 0.375 m 3 g -1 , respectively. The adsorptive property of PSAC was tested using methylene blue dye as the targeted adsorbate. Equilibrium data was best fitted by the Langmuir isotherm model, showing a monolayer adsorption capacity of 296.57 mg g -1 . The study revealed the potentiality of microwave-induced activation as a viable activation method. -- Highlights: → Pistachio nut shell activated carbon (PSAC) was prepared via microwave assisted KOH activation. → The activation step was performed at the microwave input power of 600 W and irradiation time of 7 min. → BET surface area of PSAC was 700.53 m 2 /g. → Monolayer adsorption capacity of PSAC for MB was 296.57 mg/g.

Microwave-Induced Chemotoxicity of Polydopamine-Coated Magnetic Nanocubes

KAUST Repository

Julfakyan, Khachatur; Fatieiev, Yevhen; Alsaiari, Shahad K.; Deng, Lin; Ezzeddine, Alaa; Zhang, Dingyuan; Rotello, Vincent M.; Khashab, Niveen M.

2015-01-01

Polydopamine-coated FeCo nanocubes (PDFCs) were successfully synthesized and tested under microwave irradiation of 2.45 GHz frequency and 0.86 W/cm2 power. These particles were found to be non-toxic in the absence of irradiation, but gained

Radiobiologic effects at low radiation levels

International Nuclear Information System (INIS)

Casarett, G.W.

1975-01-01

Data are reviewed on the effects of low radiation doses on mammals. Data from the 1972 report on the Biological Effects of Ionizing Radiation issued by the Advisory Committee of the National Academy of Sciences and National Research Council are discussed. It was concluded that there are certain radiosensitive systems in which low doses of radiation may cause degenerative effects, including gametogenic epithelium, lens of the eye, and developing embryos. Despite extensive investigation of genetic effects, including chromosomal effects, neither the amount of change that will be caused by very low levels of irradiation nor the degree of associated detriment is known

Synthesis of Au and Au/Cu alloy nanoparticles on multiwalled carbon nanotubes by using microwave irradiation

International Nuclear Information System (INIS)

Rangari, Vijaya K.; Dey, Sanchita; Jeelani, Shaik

2010-01-01

Gold nanoparticles and gold-copper alloy nanoparticles were synthesized by reduction of chloroauric acid (HAuCl_4.xH_2O) and co-reduction of chloroauric acid (HAuCl_4.xH_2O) and Copper(II) acetate [(CH_3COO)_2Cu.H_2O] by ethylene glycol through microwave irradiation technique. In this reaction ethylene glycol used as a solvent and also reducing agent. The cetyltrimethyl ammonium bromide (CTAB) used as surfactant. Au nanoparticles and Au-Cu nanoparticles on the surface of multiwalled carbon nanotube also produced by using same procedure. The XRD analysis confirmed the formation of Au and Au-Cu alloy nanoparticles on multiwalled carbon nanotubes(CNTs). The morphology and size of the particles were examined by the transmission electron microscopy. The EDS analysis on individual particles confirmed that the presence of two metals in a particle in case of alloy nanoparticle. The results presented here show that a variety of well defined metal and metal alloy nanoparticles can be produced by using the microwave polyol process with in a short period of time. (author)