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At least 811 records · Page 45Linked to original sources

Exploding microwaved eggs--revisited.

Different types of injuries are described as caused by the use of microwave ovens. Four of 41 burns from microwave ovens, presented by an international survey in 1986, were due to exploding microwave-heated eggs. Careful review of the English language literature through a Medline search from 1966 to 2000 was performed, in search of burns caused by exploding eggs. Clinical information from the published articles was reviewed and missing information was completed by e-mail correspondence with authors. Our own case was added to the collected data, and a total of 13 cases were analyzed. The average age of patients was 24.3 years (range, 7-49 years). All patients suffered from superficial burns of the mid and upper face, namely the forehead, periorbital region, dorsum of nose and malar areas. All patients with information available complained of ocular disturbances, and three suffered long-term decrease in visual acuity. Long-term skin complications were not reported. In summary, the clinical presentation of a facial injury from an exploding microwave-heated egg is relatively constant and mild. Favorable outcome can be expected but a meticulous ophthalmologic evaluation and a close follow-up are mandatory for prevention of long-term sequelae.

Adolescent↗

[Comparison of thawing of plasma by microwave or water bath: preliminary longitudinal biological study of hemostatic parameters].

Exploration of haemostasis was performed on plasmas thawed in an experimental microwave oven comparatively to a 37 degrees C water bath. Factor VIII:R:Ag, procoagulant and antigenic fibrinogen, and Fg:C/Fg:Ag ratio were found to be significantly, slightly decreased with microwave thawing. Factor VIII:C and VIII:C/VIII:R:Ag ratio were found to be increased with microwaves. Antigenic fractions were decreased because of partial precipitation. In addition, Fibrinogen slightly lost its activity; on the contrary, factor VIIIC was activated by micro-waves. All this allows to select parameters for new experimental microwave ovens development.

Blood Coagulation Factors↗

Rapid supplementary fixation in frozen sections: microwave versus conventional fixation. A double-blind comparative study.

The preservation of morphological details in frozen sections subjected to microwave-assisted fixation was compared with that in frozen sections subjected to snap fixation with either formalin/ethanol or ethanol alone. Especially nuclear details were better preserved after short microwave fixation. Ethanol alone gave the poorest results, with loss of nuclear details in the majority of the cases. In this study there was no significant difference between the morphological results obtained with a cheap domestic oven and that with a specialized microwave processor. Microwave-assisted fixation in frozen sections is a simple, rapid method. It is recommended for use in routine laboratories.

Artifacts↗

High-speed combinatorial synthesis utilizing microwave irradiation.

Recent advances in microwave-assisted combinatorial chemistry include high-speed solid-phase and polymer-supported organic synthesis, rapid parallel synthesis of compound libraries, and library generation by automated sequential microwave irradiation. In addition, new instrumentation for high-throughput microwave-assisted synthesis continues to be developed at a steady pace. The impressive speed combined with the unmatched control over reaction parameters justifies the growing interest in this application of microwave heating.

Combinatorial Chemistry Techniques↗

Immunolocalization of MAP-2 in routinely formalin-fixed, paraffin-embedded guinea pig brain sections using microwave irradiation: a comparison of different combinations of antibody clones and antigen retrieval buffer solutions.

The present study was designed to evaluate the efficacy of different microwave pretreatment methods to retrieve microtubule-associated protein 2 (MAP-2) immunoreactivity in formalin-fixed, paraffin-embedded guinea pig brain sections. Brain sections, microwave pretreated in boiling sodium citrate, citric acid, Tris hydrochloride, and EDTA buffers of pH 4, 6, and 8, were labeled with four different clones of MAP-2 monoclonal antibodies. No MAP-2 immunoreactivity was observed in control sections processed without microwave pretreatment. Optimal MAP-2 immunoreactivity was observed only when MAP-2 antibody clone AP18 was used in conjunction with citric acid buffer of pH 6.0. Using this combination, brain sections from nerve agent soman-exposed guinea pigs were found to exhibit marked reduction in MAP-2 immunostaining in the hippocampus. These observations suggest that the clone of the antibody in addition to the type and pH of antigen retrieval (AR) solution are important variables to be considered for establishing an optimal AR technique. When studying counterpart antigens of species other than that to which the antibodies were originally raised, different antibody clones must be tested in combination with different microwave-assisted AR (MAR) methods. This MAR method makes it possible to conduct retrospective studies on archival guinea pig brain paraffin blocks to evaluate changes in neuronal MAP-2 expression as a consequence of chemical warfare nerve agent toxicity.

Animals↗

High-temperature, microwave-assisted UV digestion: a promising sample preparation technique for trace element analysis.

A novel, microwave-assisted, high-temperature UV digestion procedure was developed for the accelerated decomposition of interfering dissolved organic carbon (DOC) prior to trace element analysis of liquid samples such as, industrial/municipal wastewater, groundwater, and surface water, body fluids, infusions, beverages, and sewage. The technique is based on a closed, pressurized, microwave digestion device. UV irradiation is generated by immersed electrodeless Cd discharge lamps (228 nm) operated by the microwave field in the oven cavity. To enhance excitation efficiency an antenna was fixed on top of the microwave lamp. The established immersion system enables maximum reaction temperatures up to 250-280 degrees C, resulting in a tremendous increase of mineralization efficiency. Compared to open UV digestion devices, decomposition time is reduced by a factor of 5 and the maximum initial concentration of DOC can be raised by at least a factor of 50. The system's performance on a real-type sample was evaluated for the mineralization of skimmed milk (IRMM, CRM 151) and subsequent determination of trace elements using standard spectroscopic techniques. Recovery for Cd (109%), Cu (112%), Fe (99%), and Pb (96%) showed good agreement with the 95% confidence interval of the certified values.

Animals↗

Microwave method for preparing erythrocytes for measurement of zinc concentration and zinc stable isotope enrichment.

A microwave digestion method to prepare human erythrocytes for measurement of Zn concentration by atomic absorption spectrophotometry and stable isotope enrichment by mass spectrometry is described. Also described is a process for purifying digested erythrocyte samples enriched with Zn stable isotope for analysis by fast atom bombardment mass spectrometry. Microwave digestion was investigated as a way to increase sample throughput by replacing a more time-consuming conventional oven ashing/hot plate wet digestion method. Pooled red blood cells and NIST bovine liver standard reference material were digested by the two different methods and zinc recoveries compared by atomic absorption spectrophotometry. Microwave and conventional methods yielded 11.7 +/- 0.1 and 11.7 +/- 0.2 micrograms/g (wet wt), respectively, for the pooled erythrocytes, and Zn recovery from NIST bovine liver standard (certified 123 +/- 8 micrograms/g) was 128.2 +/- 1.2 and 127.4 +/- 1.3 micrograms/g, p > or = 0.282, respectively. Microwave digestion improved the processing of erythrocytes for atomic absorption spectrophotometry and mass spectrometry by reducing digestion time from 1 week to 2 h. In addition, a procedure for purifying digested erythrocyte samples by either extraction and ion-exchange chromatography in preparation for mass spectrometry analysis of Zn stable isotope enrichment is outlined.

Animals↗

Microwave-swing adsorption to capture and recover vapors from air streams with activated carbon fiber cloth.

Adsorption with regeneration is a desirable means to control the emissions of organic vapors such as hazardous air pollutants (HAPs) and volatile organic compounds (VOCs) from air streams as it allows for capture, recovery, and reuse of those VOCs/HAPS. Integration of activated-carbon fiber-cloth (ACFC) adsorbent with microwave regeneration provides promise as a new adsorption/ regeneration technology. This research investigates the feasibility of using microwaves to regenerate ACFC as part of a process for capture and recovery of organic vapors from gas streams. A bench-scale fixed-bed microwave-swing adsorption (MSA) system was built and tested for adsorption of water vapor, methyl ethyl ketone (MEK), and tetrachloroethylene (PERC) from an airstream and then recovery of those vapors with microwave regeneration. The electromagnetic heating behavior of dry and vapor-saturated ACFC was also characterized. The MSA system successfully adsorbed organic vapors from the airstreams, allowed for rapid regeneration of the ACFC cartridge, and recovered the water and organic vapors as liquids.

Adsorption↗

Alkaline dissolution of starch facilitated by microwave heating for analysis by size-exclusion chromatography.

A rapid, straightforward starch dissolution method was developed to facilitate analysis of starch by size-exclusion chromatrography (SEC). Soft wheat starch was dispersed in 6 M urea and 1 M KOH and subjected to heating for 35, 45, or 60 s in a microwave oven as a potential means of starch dissolution. An increase in microwave heating time enhanced starch solubility but resulted in a steady decrease in amylopectin peak area and a consequent, artifactual increase in the amylose peak area due to molecular degradation. However, microwave heating for 35 s afforded a reasonable separation of starch fractions by SEC while minimizing molecular degradation of starch in comparison to a traditional starch dissolution procedure. This procedure provides a fast (<30 min), simple, and reproducible starch dissolution method for preparation of starches for SEC analysis and represents the first successful report of direct dissolution of granular starch via microwave heating.

Chromatography, Gel↗

Microwave-enhanced ink staining for fast and sensitive protein quantification in proteomic studies.

A novel microwave-enhanced ink staining method was developed for rapid and sensitive estimation of protein content in sample buffers containing chaotropes, dyes, detergents, and reducing agents. Dye-based Blue-Black ink was used to quantitatively visualize proteins spotted on a nitrocellulose membrane. The total staining time was greatly reduced to 3 min by brief exposure to microwave radiation. The stained membrane was washed with distilled water, baked in a microwave oven for complete desiccation, transparentized with mineral oil, and documented by a desktop scanner or densitometer. Only 1 microL of protein sample (protein solubilized in SDS-PAGE sample buffer or IEF rehydration buffer) was used for protein spotting. The novel solid-phase protein assay gives a 500-fold dynamic range from 19.5 to 10000 ng/microL and can be scaled up for high-throughput protein quantification analysis. The fast, sensitive and low-cost microwave-enhanced ink staining procedure is ideal for protein quantification in proteomic analysis.

Animals↗

Microwave staining of intestinal whole-mount preparations with Cuprolinic blue.

Encouraged by the knowledge that microwaves have a beneficial effect on immunohistochemical reactions, the present study aimed to find out whether microwaves could improve the Cuprolinic Blue staining of enteric neurons as well as the actual method that has been developed for gastrointestinal whole-mount preparations. In addition to incorporating a microwave application in the method described by Holst and Powley (1995), some other modifications were made: two incubations before incubation in the staining solution and free-floating incubations. In the whole-mount preparations, most, if not all, enteric neurons were stained by Cuprolinic Blue. These neurons appeared as blue-green cells with non-reacting nuclei and neuronal processes. At higher magnification, the cytoplasm was characterized by a fine blue-green granulation, and the nucleolus in the nucleus appeared as a blue iridescent structure. Non-specific staining occurred in fibrocytes and epithelial cells but, because of their location and appearance, they could easily be distinguished from neurons. The modified incubations and the incorporation of a microwave application into the conventional Cuprolinic Blue staining method turn the method into an easy-to-use one that seems to visualize most, if not all, enteric neurons in whole-mount preparations of the pig jejunum.

Animals↗

Pulsing microwave energy: a method to create more uniform myocardial temperature gradients.

Microwave energy has been proposed as a possible technique to create large myocardial lesions. Achieving a uniform myocardial temperature gradient during microwave ablation may prevent excessive endocardial temperatures while maintaining temperatures at depth. The goal of the current study was to examine the ability of microwave (MW) pulsing to achieve a more uniform myocardial temperature gradient. Using an in-vitro ovine endocardial model, we measured tissue temperature at 0.5-mm, 2.0-mm, and 3.5-mm depths in a circulating saline bath. MW energy was delivered at 20 W at 915 MHz for 30 seconds. Pulse configurations of 1 second on-1 second off, 3 seconds on-3 seconds off, and 5 seconds on-5 seconds off, with 30 seconds of total MW time were compared with 30-seconds continuous. Maximum temperatures at 0.5 mm were significantly lower at 63.2 +/- 5.89 degrees C for the 1-second pulse compared with 83.5 +/- 7.31 degrees C for the continuous-energy delivery. Pulse configurations 3 seconds on-3 seconds off and 5 seconds on-5 seconds off also resulted in a significantly lower surface temperature than continuous-energy delivery. However, temperature at the 2.0-mm and 3.5-mm depth created by the pulsing delivery were similar to those achieved during continuous-energy delivery. Thus, microwave pulsing achieves a lower endocardial temperature and results in a more uniform temperature gradient. These techniques may prevent the excessive endocardial damage that may result in an increased risk of thrombus formation and embolization.

Animals↗

Microwave drying of selected greens and their sensory characteristics.

Green leafy vegetables which supply minerals and vitamins to the diet, are highly perishable. Therefore, post harvest losses are extremely high. Limited studies are available in the literature with regard to preservation of greens. The effect of microwave drying and storage on physical and sensory properties of selected greens (coriander, mint, fenugreek, amaranth and shepu) were therefore studied. Microwave drying was carried out at 100% power and a frequency of 2450 mHz. The drying time varied from 10 to 16 min for different greens. Microwave drying affected color, appearance and odor of all the greens. The relative reconstitution capacity (RRC) for different greens was coriander-10.3, mint-10.3, amaranth-38.3, fenugreek-31.7 and shepu-32.8. The RRC appeared to influence acceptability. Coriander and mint, which exhibited the lowest RRC (10.3%), had the lowest scores for flavor and color while amaranth, with the highest RRC (38.3%), had scores similar to those of fresh amaranth. Scores for the products prepared with dried fenugreek and shepu, although low, were not statistically significant. Microwave drying was highly suitable for greens such as amaranth; moderately suitable for shepu and fenugreek and less suitable for coriander and mint.

Amaranthus↗

The development of a microwave fluid-bed processor. II. Drying performance and physical characteristics of typical pharmaceutical granulations.

Four typical pharmaceutical granulations were used to measure the enhanced drying performance of a laboratory-sized microwave fluid-bed processor, the design and construction of which were presented in Part I of this work (preceding paper). Results demonstrate improvements in observed drying rates by as much as sixfold depending upon the granulation type and drying conditions. At a low inlet temperature (30 degrees C), drying was achieved with microwave power inputs of 100-125 W/liter of working capacity, whereas similar targeted moisture levels were unattainable using conventional fluid-bed drying. Microwave energy available for heating and drying was 68 to 86% of the total microwave energy inputted.

Desiccation↗

The development of a microwave fluid-bed processor. I. Construction and qualification of a prototype laboratory unit.

The static bed- and planetary-type microwave dryers currently available to process pharmaceutical materials are not designed to use hot-air fluidization for the purpose of maximizing microwave energy inputs and particle drying. To take advantage of the benefits offered by fluidization, a 1-kg Uni-Gatt laboratory fluid bed processor was modified to support microwave-assisted fluid bed drying of several representative pharmaceutical granulations. The construction, design features, and validation of this new microwave fluid bed processor are presented.

Calibration↗

Microwave-assisted synthesis of galacto-oligosaccharides from lactose with immobilized beta-galactosidase from Kluyveromyces lactis.

Galacto-oligosaccharides (GOS) were synthesized from lactose by immobilized and free beta-galactosidase from Kluyveromyces lactis (Lactozym 3000 L HP-G) using either focused microwave irradiation or conventional heating. Immobilization of the beta-galactosidase on to Duolite A-568 increased the synthesis of GOS. GOS selectivity (GOS synthesis/lactose hydrolysis ratio) increased when the water activity of the media was reduced, notably with a high initial lactose concentration but also by using co-solvents in the media. The advantage of microwave heating on GOS formation was also examined. Addition of solvent and carrying out the reaction under microwave irradiation resulted an increase in the production of GOS. The selectivity for GOS synthesis can be increased by 217-fold under microwave irradiation, using immobilized beta-glucosidase and with added co-solvents such as hexanol.

Enzymes, Immobilized↗

Microwave detection of metastasized breast cancer cells in the lymph node; potential application for sentinel lymphadenectomy.

Metastasis is the leading cause of death in breast cancer patients and an appropriate detection of metastasis can provide better prognosis and quality treatments. Microwaves can reveal the unique electromagnetic properties of materials, and this study aims to unleash the electromagnetic properties of breast cancer cells, especially, metastasized cancer cells in the lymph nodes, using broad-band microwaves in attempts to detect metastases. To distinguish the cancer-specific patterns of cancer tissues, three primary microwave parameters were assessed, i.e., permittivity in mid-band frequency (3-5 GHz), conductivity in high-band frequencies (25-30 GHz) and slope changes of permittivity at high-band frequencies (15-30 GHz). An additional parameter, Cancer Metastasis Index (CMI), was developed to effectively represent all parameters. Broadband microwave scanning can reveal cancer specific electromagnetic behaviors in all three parameters, and these were reliably reflected by CMI. CMI effectively magnified the difference of the electromagnetic properties between normal nodal tissues and cancer tissues. immunohistochemistries were performed to verify the origin of electromagnetic changes represented by CMI values.

Breast Neoplasms↗

In vitro and in vivo evaluation of the thermal patterns and lesions of catheter ablation with a microwave monopole antenna.

BACKGROUND: Radiofrequency (RF) catheter ablation is an effective treatment for supraventricular tachycardia. The effectiveness of the technique is at times limited by the small lesion size produced by RF energy delivery. Previous reports have indicated that microwave energy is capable of producing a larger volume of heated tissue than radiofrequency energy, raising the possibility that microwave energy may offer a potential alternative energy source to radiofrequency for the substrate ablation of certain arrhythmias such as ventricular tachycardia or atrial flutter. METHODS: The present study evaluated the thermal profiles of a monopole microwave antenna delivering energy at 2.45 GHz frequency in a phantom tissue-equivalent material with dielectric and thermal properties similar to myocardium. In addition, microwave catheter ablations were performed in vivo in the ventricles of goats prior to the examination of the lesions. RESULTS: The measured thermal profiles in the phantom revealed that the antenna is capable of producing heating to a temperature associated with myocardial necrosis to a controllable depth that can be more than 8 mm, while the endocardial temperature is maintained relatively low. The ablation volume is significantly reduced but is still effective when there is only a partial contact between the antenna and the tissue surface. In vivo studies on goat models confirmed that the monopole antenna can produce a deep transmural lesion in the left ventricle without causing coagulation or charring on the endocardial surface.

Animals↗