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Electrostatic Charge (electrostatic + charge)
Selected AbstractsPatterning of Electrostatic Charge on Electrets Using Hot Microcontact Printing,ANGEWANDTE CHEMIE, Issue 36 2009Dan Zhao Heiße Sache: Ein topographisch gemusterter Poly(dimethylsiloxan)(PDMS)-Stempel wird auf 50,220,°C erhitzt und nutzt dann diese Wärmeenergie als ,Tinte" für ein Mikrokontaktdrucken (,CP), indem er chemisches Vernetzen, Zersetzen oder andere Umwandlungen auslöst. Die Heiß-,CP-Technik kann Muster aus elektrostatischen Ladungen auf Elektreten durch selektive thermisch stimulierte Entladung (TSD, siehe Bild) oder Depolarisierung erzeugen. [source] Selective Discharge of Electrostatic Charges on Electrets Using a Patterned Hydrogel Stamp,ANGEWANDTE CHEMIE, Issue 32 2010Xinlei Ma Malen mit Wasser: Ein topographisch gemusterter Stempel aus Agarosehydrogel wird genutzt, um Wasser , zum Zweck einer selektiven Entladung , auf einheitlich geladene PMMA-Elektrete zu drucken. Die hochaufgelösten elektrostatischen Ladungsmuster, die durch diesen einfachen Ansatz erzeugt werden, können die Reduktion von Metallionen induzieren und ermöglichen so die Herstellung von mikro- und nanoskaligen Metallstrukturen. PMMA=Polymethylmethacrylat. [source] Anomalous electrophoretic behavior of a very acidic protein: Ribonuclease U2ELECTROPHORESIS, Issue 18 2005Lucía García-Ortega Abstract Ribonuclease U2 is a low-molecular-weight acidic protein with three disulfide bridges. This protein displays an anomalous electrophoretic behavior on standard SDS-PAGE. The electrophoretic mobility of the nonreduced protein roughly corresponds to its molecular mass while the migration of the reduced protein would be in accordance with the expected molecular mass of the protein dimer. This study reveals that the protein does not bind SDS under the SDS-PAGE conditions, its electrophoretic mobility being only determined by its electrostatic charge and hydrodynamic properties. In addition, the nonreduced protein cannot be blotted to a membrane. Unfolding of the protein upon reduction of its disulfide bridges enables electrotransference to membranes due to a restricted diffusion along the electrophoresis gel. [source] Adhesive powder uptake and transfer by Mediterranean fruit flies, Ceratitis capitata (Dipt., Tephritidae)JOURNAL OF APPLIED ENTOMOLOGY, Issue 5 2006L. Barton Abstract:, EntostatTM is an electrostatically charged wax powder that is used as a carrier particle in novel delivery systems for contaminating target insect pests with insecticides, biologicals or pheromones. Here, the adhesion of two forms of Entostat to the Mediterranean fruit fly (medfly) Ceratitis capitata (Wiedemann) was examined, and the adhesion of Entostat to live and dead medflies was compared. From controlled contaminations of medflies, it was shown that live medflies acquired larger quantities of Entostat than dead medflies, which could be due to the electrostatic charge shown to be carried by live insects. Air-milled Entostat (7.59 ,m mean diameter) adhered in larger quantities to medflies than pestle and mortar-ground Entostat (9.17 ,m mean diameter). Exposing medflies to different quantities of Entostat affected the initially adhering quantity but did not alter the proportion of powder retained over time. Medfly males contaminated with air-milled Entostat were shown to transfer small quantities to females during mating. This documentation of secondary powder transfer underscores the potential for using slow-acting killing agents on the basis of this delivery system. [source] Isoelectric points of virusesJOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2010B. Michen Summary Viruses as well as other (bio-)colloids possess a pH-dependent surface charge in polar media such as water. This electrostatic charge determines the mobility of the soft particle in an electric field and thus governs its colloidal behaviour which plays a major role in virus sorption processes. The pH value at which the net surface charge switches its sign is referred to as the isoelectric point (abbreviations: pI or IEP) and is a characteristic parameter of the virion in equilibrium with its environmental water chemistry. Here, we review the IEP measurements of viruses that replicate in hosts of kingdom plantae, bacteria and animalia. IEPs of viruses are found in pH range from 1·9 to 8·4; most frequently, they are measured in a band of 3·5 < IEP < 7. However, the data appear to be scattered widely within single virus species. This discrepancy is discussed and should be considered when IEP values are used to account for virus sorption processes. [source] Electrostatic effects on inertial particle transport in bifurcated tubesAICHE JOURNAL, Issue 6 2009Fong Yew Leong Abstract Most aerosols found naturally in the ambient environment or those dispersed from artificial devices such as dry powder inhalers, are electrically charged. It is known that a strong electrostatic charge on aerosols can result in transport behavior dramatically different from that of uncharged aerosols, even in the absence of an external electric field. In the present work, we study pneumatic transport of corona-charged particles in bifurcated tubes. This is accomplished by tracking the motion of discrete particles numerically under the influence of drag, gravitational, and electrostatic forces. The model aerosol is fly ash powder, whose size and charge distributions have been determined experimentally. The electrical mobility of the charged particle cloud is modeled through coulombic interactions between discrete point charges. For the case of polydispersed particles electrically charged across a distribution, the deposition efficiency was found to be greater than what is indicated by the mean charge and size. In particular, use of negatively charged fly ash powder of mean size of 2 ,m and mean charge of ,1.5 C/kg led to significant increase in deposition efficiency (,29%) compared with uncharged fly ash powder of the same size distribution (,8%). Analysis of particle residence times suggests significant interaction between electrical and drag forces. These findings could have implications for pneumatic powder conveying or pulmonary drug delivery applications. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Triboelectrification of Spray-dried Lactose Prepared from Different Feedstock ConcentrationsJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 1 2000ORLA E. CASSIDY Powder systems may acquire electrostatic charge during various pharmaceutical processing operations and may give rise to difficulties in handling and powder flow, mainly due to adhesion/cohesion effects. We have investigated the electrostatic charging of spray-dried lactose prepared from different feedstock concentrations using a laboratory spray-dryer. Triboelectrification of the spray-dried lactose samples was effected through contact with the stainless steel surface of either a mixing vessel or a cyclone separator. Results from both techniques showed differences in charge accumulation and particle-steel adhesion between the spray-dried lactose samples. As the feedstock concentration used to produce the spray-dried lactose was increased in the range 10,50% w/v, the mean charge on the lactose decreased from ,20.8 to ,1.3 nC g,1 and ,54.9 to ,4.1 nC g,1 for the mixing vessel and cyclone separator, respectively, with a corresponding decrease in adhesion. In addition, as the feedstock concentration was increased from 10 to 50% w/v, decreases were obtained in surface area values (1.06 to 0.56 m2 g,1), pore diameter (198.7 to 83.5 ,m) and pore volume (1.09 to 0.75 cm3 g,1), and together with differences in crystal form correlated with the charge and adhesion results. The results suggested that the feedstock concentration could have a considerable influence on the charging and adhesional properties of spray-dried lactose. This may have relevance during pharmaceutical processing and manufacturing operations. [source] Development of a packaging material using non-bleed-type antistatic ionomerPACKAGING TECHNOLOGY AND SCIENCE, Issue 5 2004Nobuyuki Maki Abstract Generally, plastics and plastic films are low in moisture absorption and high in electric insulation. They are inherently vulnerable to static charge build-up, which can result in a variety of problems. We have developed a functional packaging material to solve these static problems, by using a potassium salt of ethylene ionomer, which is a non-bleed-type antistatic agent. Good antistatic performance was shown by evaluating a variety of electric characteristics (e.g. the static decay time, ash test and saturated electrostatic charge and half-life) and surface resistivity. In addition, antistatic performance was achieved on the mLLDPE (non-treated) side in a multilayer structure. This means that the use of potassium ionomer on any layers in a multilayer structure provides antistatic performance, leading to the expectation of developing a wide variety and diversity of packaging materials. Copyright © 2004 John Wiley & Sons, Ltd. [source] Electrostatic Charge Measurement and Charge Neutralization of Fine Aerosol Particles during the Generation ProcessPARTICLE & PARTICLE SYSTEMS CHARACTERIZATION, Issue 5 2005Chuen-Jinn Tsai Abstract An aerosol charge analyzer has been constructed to measure the charge distribution of NaCl particles generated in the laboratory. A radioactive electrostatic charge neutralizer utilizing Po-210 was used to neutralize the electrostatic charge of the particles. The atomization technique was used to generate NaCl particles with diameters of 0.2 to 0.8 ,m, while the evaporation and condensation method was adopted to generate particles of 0.01 to 0.2 ,m in diameter. The experimental data demonstrates that the absolute average particle charge depends on the particle diameter, and is higher than that calculated by the Boltzmann charge equilibrium for particles within the range of 0.2 to 0.8 ,m. The charge increases with decreasing NaCl concentration. When these particles are neutralized using the Po-210 neutralizer, it is found that the electrostatic charge reaches the Boltzmann charge equilibrium. For 0.01 to 0.2 ,m NaCl particles generated using the evaporation and condensation method, test results show that the absolute average particle charge is higher than that calculated by the Boltzmann charge equilibrium for particles larger than 0.03 to 0.05 ,m in diameter, while it is lower than that predicted by the Fuchs theory [1], for particles smaller than 0.03 to 0.05 ,m. However, after charge neutralization, particles with diameter above 0.05 ,m reach the Boltzmann charge equilibrium condition, and the charges for particles with diameters of 0.010 to 0.05 ,m, agree well with Fuchs' theory. [source] In vivo comparison of the relative systemic bioavailability of fluticasone propionate from three anti-static spacers and a metered dose inhalerBRITISH JOURNAL OF CLINICAL PHARMACOLOGY, Issue 2 2009Arun Nair WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT , Conventional spacers help overcome problems with co-ordination and may improve lung deposition and decrease oropharyngeal impaction. , Antistatic spacers eliminate electrostatic charge and may hence improve respirable dose delivery. , The systemic bioavailability of inhaled fluticasone propionate is primarily dependent on delivery by the pulmonary route and hence the performance of antistatic spacers can be evaluated using adrenal suppression as a sensitive surrogate for relative bioavailability to the lung after an inhalation. WHAT THIS STUDY ADDS , This study compares the relative bioavailability to the lung of inhaled fluticasone delivered via conventional pressurized metered dose inhalers (pMDI) and three antistatic spacers (plastic Zerostat-V, plastic Aerochamber Max, and metal Nebuchamber) in patients with asthma. , All three antistatic spacers when compared with pMDI significantly increased the relative bioavailability to the lungs of inhaled fluticasone in terms of relative adrenal suppression, and there were no significant differences between the plastic and metal antistatic spacers. AIMS The systemic bioavailability of inhaled fluticasone propionate (FP) depends primarily on lung absorption and can be quantified by measuring suppression of overnight and early morning urinary cortisol/creatinine (OUCC and EMUCC, respectively). The aim of the study was to determine the relative bioavailability of hydrofluoroalkane (HFA) FP to the lungs via anti-static plastic (Zerostat-V and Aerochamber Max), metal (Nebuchamber) anti-static spacers and metered dose inhaler [Flixotide Evohaler (EH) (pMDI)]. METHODS A randomized, double-blind, double-dummy, four-way crossover design was used. Eighteen mild to moderate asthmatics received single doses of placebo/HFA-FP 2 mg via the 280-ml Zerostat-V (ZS); 250-ml Nebuchamber (NC); 197-ml Aerochamber Max (AC); and pMDI (EH). Measurements of OUCC and EMUCC were made at baseline and 10 h after each dose. RESULTS Significant suppression of OUCC and EMUCC occurred from baseline with all three spacers, but not Evohaler (geometric mean fold suppression, 95% confidence interval): ZS, 2.74 (1.75, 4.30), P < 0.001; NC, 3.31 (1.81, 6.06), P < 0.001; AC, 4.98 (3.39, 7.31), P < 0.001; and for EH this was 1.42 (0.92, 2.21), P= 0.169 (equating to a 64, 70, 80 and 30% fall in OUCC via the ZS, NC, AC and EH devices, respectively). There were significant differences between all three spacers vs. EH. When compared with the Evohaler, the Zerostat V resulted in 48% greater suppression (P= 0.009); the Nebuchamber 57% greater suppression (P= 0.001); and the Aerochamber Max 71% greater suppression of OUCC (P < 0.001). CONCLUSION All three antistatic spacers significantly increased the relative systemic bioavailability of HFA-FP compared with the standard pMDI. [source] Copper Azide Confined Inside Templated Carbon NanotubesADVANCED FUNCTIONAL MATERIALS, Issue 18 2010Valarie Pelletier Abstract The currently used primary explosives, such as lead azide and lead styphnate, present serious health hazards due to the toxicity of lead. There is a need to replace them with equally energetic but safer-to-handle and more environmentally friendly materials. Copper azide is more environmentally acceptable, but very sensitive and detonates easily from electrostatic charges during handling. If the highly sensitive copper azide is encapsulated within conducting containers, such as anodic aluminum oxide (AAO)-templated carbon nanotubes (CNTs), its sensitivity can be tamed. This work describes a technique for confining energetic copper azide within CNTs. ,5 nm colloidal copper oxide nanoparticles are synthesized and filled into the 200 nm diameter CNTs, produced by template synthesis. The Cu-O inside the CNTs is reduced in hydrogen to copper, and reacted with hydrazoic acid gas to produce copper azide. Upon initiation, the 60 ,m long straight, open-ended CNTs guide decomposition gases along the tube channel without fracturing the nanotube walls. These novel materials have potential for applications as nano-detonators and green primary explosives; they also offer new opportunities for understanding the physics of detonation at the nanoscale. [source] Role of the surface charges D72 and K8 in the function and structural stability of the cytochrome c6 from Nostoc sp.FEBS JOURNAL, Issue 13 2005PCC 711 We investigated the role of electrostatic charges at positions D72 and K8 in the function and structural stability of cytochrome c6 from Nostoc sp. PCC 7119 (cyt c6). A series of mutant forms was generated to span the possible combinations of charge neutralization (by mutation to alanine) and charge inversion (by mutation to lysine and aspartate, respectively) in these positions. All forms of cyt c6 were functionally characterized by laser flash absorption spectroscopy, and their stability was probed by urea-induced folding equilibrium relaxation experiments and differential scanning calorimetry. Neutralization or inversion of the positive charge at position K8 reduced the efficiency of electron transfer to photosystem I. This effect could not be reversed by compensating for the change in global charge that had been introduced by the mutation, indicating a specific role for K8 in the formation of the electron transfer complex between cyt c6 and photosystem I. Replacement of D72 by asparagine or lysine increased the efficiency of electron transfer to photosystem I, but destabilized the protein. D72 apparently participates in electrostatic interactions that stabilize the structure of cyt c6. The destabilizing effect was reduced when aspartate was replaced by the small amino acid alanine. Complementing the mutation D72A with a charge neutralization or inversion at position K8 led to mutant forms of cyt c6 that were more stable than the wild-type under all tested conditions. [source] Charge generation during filling of insulated tanksPROCESS SAFETY PROGRESS, Issue 3 2002Migvia Vidal This research involves charge generation measurements for various flammable fluids during filling of insulated tanks and relating static charging with flow rate and physicochemical parameters, especially changes in electrical conductivity. The objective is to correlate static charge measured inside baffled metal and polyethylene tanks as a function of impeller, Reynolds number, and the electrical conductivity of both the hydrocarbon and the dispersed water phase for a variety of flammable liquids. A product of the research is a correlation for polyethylene and other plastic insulated tanks for transfers of low conductivity liquid fuels. Also, a universal (dimensionless) correlation that relates the charging data to the colloidal nature of the mixture will be developed for static charge generation during impeller mixing of light hydrocarbons containing various concentrations of water in cylindrical tanks. The correlation of electrostatic data from this research will help make it possible to control electrostatic charges, and, as a result, greatly improve safety of operations involving flammable fluids in industry. [source] | |||||||||||||||||||