Home About us Contact
|
Home About us Contact | ||
|
|
||
Microcapsules
Kinds of Microcapsules Selected AbstractsEncapsulation of a Single Metal Nanoparticle with Tunable Size in a Monodisperse Polymer MicrocapsuleMACROMOLECULAR RAPID COMMUNICATIONS, Issue 3 2009Haiqing Li Abstract A versatile approach to fabricate monodisperse poly[styrene- co -(divinyl benzene)] (PS- co -DVB) microcapsules that contain a single gold nanoparticle (AuNP) has been demonstrated. Using the PS- co -DVB microcapsule as a microreactor, aqueous HAuCl4 and NaBH4 solutions are subsequently infiltrated. The size of the resulting AuNP inside of the PS- co -DVB microcapsules is easily tunable by controlling the repeated infiltration cycles of aqueous HAuCl4 and NaBH4. PS- co -DVB microcapsules that contain a single silver and palladium nanoparticle are also obtained by following a similar protocol. [source] Microencapsulation of n -Eicosane as Energy Storage MaterialCHINESE JOURNAL OF CHEMISTRY, Issue 5 2004Xiao-Zheng Lan Abstract For heat energy storage application, polyurea microcapsules containing phase change material, n -eicosane, were synthesized by using interfacial polymerization method with toluene-2,4-diisocyanate (TDI) and diethylenetriamine (DETA) as monomers in an emulsion system. Poly(ethylene glycol)octyl-phenyl ether (OP), a nonionic surfactant, was the emulsifier for the system. The experimental result indicates that TDI was reacted with DETA in a mass ratio of 3 to 1. FT-IR spectra confirm the formation of wall material, polyurea, from the two monomers, TDI and DETA. Encapsulation efficiency of n -eicosane is about 75%. Microcapsule of n -eicosane melts at a temperature close to that of n -eicosane, while its stored heat energy varies with core material n -eicosane when wall material fixed. Thermo-gravimetric analysis shows that core material n -eicosane, micro- n -eicosane and wall material polyurea can withstand temperatures up to 130, 170 and 250 °C, respectively. [source] Preparation and thermal properties of microencapsulated phase change material for enhancing fluid flow heat transferHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 1 2007Yu Rao Abstract Microencapsulated phase change material (MEPCM) is formed by packing PCM into a microcapsule with a solid but flexible shell. MEPCM can be used to enhance liquid cooling performance considerably. In this paper, experiments on the preparation of MEPCM with a double-layered shell have been conducted. An in-situ polymerization microencapsulation process was used to prepare the MEPCM with melamine resin as the shell material and n-Docosane (C22H46) as the core material. Interesting parameters like the size of the prepared MEPCM, the core mass fraction in the MEPCM, and the thermal storage capability of the prepared MEPCM have been measured and analyzed. © 2006 Wiley Periodicals, Inc. Heat Trans Asian Res, 36(1): 28,37, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20138 [source] Ultrabubble: A Laminated Ultrasound Contrast Agent with Narrow Size RangeADVANCED MATERIALS, Issue 38-39 2009Pei-Lun Lin A laminated shell microcapsule is described resisting aggregation and withstanding ultrasound destruction, showing a good backscatter signal, as shown in the figure. Templated synthesis produces versatile monodisperse capsules <3 µm, with ultrasound-pressure dependency allowing rupture above MI , 1.5 (at 2 MHz), suitable for future development as both controlled-delivery agent and contrast agent. [source] The microencapsulation of terbinafine via in situ polymerization of melamine-formaldehyde and their application to cotton fabricJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Gökhan Erkan Abstract In this study an antifungal pharmaceutical agent, terbinafine, was microencapsulated by using in situ polymerization. The polymerization was carried out at four mole ratio level and preparations were applied to the 100% cotton fabric. X-ray diffractometry, DSC, FTIR, BET, contact angle measurements, particle size distribution and imaging techniques were performed. Best results were obtained in the case of 8 : 1 mole ratio. Strength of microcapsule applied fabrics to washing and fungus were also determined. After 25 washing cycle, microcapsules were still in the fabric and had antifungal properties against A. niger. Antifungal strength against T. rubrum was observed up to 15 washing cycles. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Preparation and characterization of quercetin-loaded polymethyl methacrylate microcapsules using a polyol-in-oil-in-polyol emulsion solvent evaporation methodJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 12 2007Dong-Hwan Lee Flavonoids and related compounds exhibit a wide range of useful pharmacological properties but present challenges related to their stability and solubility in commonly available solvents. In this study, polymethyl methacrylate (PMMA) microcapsules were prepared using a novel polyol-in-oil-in-polyol (P/O/P) emulsion solvent evaporation method as a means of stabilizing the flavonoids, using quercetin as a model flavonoid drug. The morphology of the microcapsules was evaluated using a scanning electron microscope, revealing a spherical shape with a smooth surface. The cross-section image of the PMMA microcapsules prepared with an amphiphilic polymer in the inner polyol phase showed that the microcapsule was filled with several submicron microspheres. The mean diameter varied from 1.03 ± 0.12 ,m to 2.39 ± 0.42 ,m, and the encapsulation efficiency ranged from 12.7% to 26.9%. When free quercetin was stored at 42°C, the residual quercetin content gradually decreased to 18% over 28 days as a result of oxidation. However, when encapsulated in PMMA microcapsules with an amphiphilic polymer in the inner polyol phase, the residual quercetin content decreased to just 82%. In-vitro release studies indicated a sustained release pattern throughout the 36-h study. The release kinetics of the microcapsules with an amphiphilic polymer followed a diffusion-controlled mechanism and the microcapsule without amphiphilic polymer followed an anomalous diffusion behaviour. This study suggests that the novel P/O/P emulsion solvent evaporation method can be applied to the encapsulation of flavonoids. [source] Encapsulation of a Single Metal Nanoparticle with Tunable Size in a Monodisperse Polymer MicrocapsuleMACROMOLECULAR RAPID COMMUNICATIONS, Issue 3 2009Haiqing Li Abstract A versatile approach to fabricate monodisperse poly[styrene- co -(divinyl benzene)] (PS- co -DVB) microcapsules that contain a single gold nanoparticle (AuNP) has been demonstrated. Using the PS- co -DVB microcapsule as a microreactor, aqueous HAuCl4 and NaBH4 solutions are subsequently infiltrated. The size of the resulting AuNP inside of the PS- co -DVB microcapsules is easily tunable by controlling the repeated infiltration cycles of aqueous HAuCl4 and NaBH4. PS- co -DVB microcapsules that contain a single silver and palladium nanoparticle are also obtained by following a similar protocol. [source] Microencapsulated ammonium polyphosphate with polyurethane shell: preparation, characterization, and its flame retardance in polyurethanePOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 6 2010Jianxiong Ni Abstract A series of polyurethane (PU) microencapsulated ammonium polyphosphate (MCAPP) were prepared by in situ polymerization from toluene-2,4-diisocyanate (TDI), polyethylene glycol (PEG), and pentaerythtritol (PER). And the structure was characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Then it chose the optimal PEG constituent to design microcapsule from scanning electron microscopy (SEM) and water solubility test. The combustion and thermal degradation behaviors of PU blended APP or MCAPP were investigated by thermogravimetric analysis (TGA), UL-94 test, and microcombustion calorimetry. The results showed that the PU/MCAPP had better thermal stability and flame retardance, due to the stable char forming by APP and PU shell. Moreover, the water resistance of flame retarded PU composite was greatly improved. Copyright © 2009 John Wiley & Sons, Ltd. [source] Towards an inert diet for first-feeding gilthead seabream Sparus aurata L. larvaeAQUACULTURE NUTRITION, Issue 3 2000Yúfera The development of an inert food to replace live prey during the early stages of marine fish larvae requires research in different fields and therefore a precise work strategy. Our research on this subject has been carried out in successive steps using the gilthead seabream Sparus aurata. The first step was the design of a food particle that would be well accepted and ingested by free-swimming marine larval fish during the first developmental stages. We chose microencapsulation by polymerization of the dietary protein as the most appropriate method for making the particles; different types of microcapsules were made using a basic diet containing only the major dietary components. In the second step, our aim was to keep the larvae alive in a routine rearing system in 300-L tanks, using exclusively this kind of food, long enough to detect any changes in growth, survival, or anatomical and histological status of the larvae, in order to verify whether the technological changes were positive. The third step focused on diet formulation and searching for clues to inefficient assimilation and growth. The use of ,in vitro' digestibility techniques allowed us to detect the inhibitory effect of some diet ingredients on larval proteases and to determine more suitable sources of protein. We now have a microcapsule able to efficiently support growth and development of S. aurata larvae, at least during the first 2 weeks of life, although the larvae still need to feed on rotifers during the first 2,4 days of exogenous feeding. This microcapsule will make it possible to make advances in determining the specific nutritional requirements of larval fish. [source] Microencapsulation of an anti-VE,cadherin antibody secreting 1B5 hybridoma cellsBIOTECHNOLOGY & BIOENGINEERING, Issue 4 2001G. Orive Accumulating experimental evidence demonstrates that tumor growth and lethality are dependent on angiogenesis. Based on this concept, there is growing interest in the use of antiangiogenesis agents to inhibit tumor expansion. Compelling data implicate vascular endothelium (VE),cadherin (an endothelium specific protein) as a key factor in the last step of angiogenesis, where the endothelial cells join one to each other and form microtubules (future blood vessels). We propose a novel approach to the inhibition of angiogenesis by immobilizing VE,cadherin-secreting hybridoma cells in alginate,agarose microcapsules. Hybridoma cells can be protected with biocompatible and semipermeable membranes that permit exit of anti-VE,cadherin monoclonal antibodies but not entry of cellular immune mediators. Stability studies were performed to select the suitable microcapsule for cell immobilization. Alginate and agarose solid beads coated with poly- L -lysine and alginate were chosen according to their stability and diffusional properties. 1B5 hybridoma cells were grown within the microcapsules and secreted anti-VE,cadherin antibodies during the 9 days of culture, reaching a cumulative concentration of 1.7 ,g/mL. This antibody concentration inhibited microtubule formation (87%) in the in vitro angiogenesis Matrigel assay. Moreover, the antiangiogenic effect observed was antibody concentration related. These findings open a new alternative for the inhibition or prevention of angiogenesis and demonstrates the feasibility of using microencapsulated cells as a control-drug delivery system. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 76: 285,294, 2001. [source] Applying SEM-Based X-ray Microtomography to Observe Self-Healing in Solvent Encapsulated Thermoplastic Materials,ADVANCED ENGINEERING MATERIALS, Issue 3 2010Steven D. Mookhoek In this work X-ray microtomography was used to observe fracture and healing processes in a liquid-based self-healing thermoplastic material. The method was able to produce data of sufficient resolution (<10,,m) to observe ,60,,m microcapsules containing solvent within a polymeric material and in particular their behavior around a crack zone after fracture and healing. The reconstructed data showed the distribution of filled and several empty microcapsules within the matrix material. Additional color segmentation and 3D rendering of the data unambiguously demonstrated a large concentration of ruptured microcapsules near the fracture surfaces, covering ,75,,m span on both sides of the crack. A close investigation of the crack area confirmed the presence of healed and non-healed regions. Further analysis of the segmented data allowed a quantitative determination of the release of the encapsulated solvent. [source] Contact-Killing Polyelectrolyte Microcapsules Based on Chitosan DerivativesADVANCED FUNCTIONAL MATERIALS, Issue 19 2010Di Cui Abstract Polyelectrolyte-multilayer microcapsules are made by layer-by-layer (LbL) assembly of oppositely charged polyelectrolytes onto sacrificial colloidal particles, followed by core removal. In this paper, contact-killing polyelectrolyte microcapsules are prepared based solely on polysaccharides. To this end, water-soluble quaternized chitosan (QCHI) with varying degrees of substitution (DS) and hyaluronic acid (HA) are assembled into thin films. The quaternary ammonium groups are selectively grafted on the primary amine group of chitosan by exploiting its reaction with glycidyltrimethylammonium chloride (GTMAC) under homogeneous aqueous acidic conditions. The morphology of the capsules is closely dependent on the DS of the quaternized chitosan derivatives, which suggests differences in their complexation with HA. The DS is also a key parameter to control the antibacterial activity of QCHI against Escherichia Coli (E. coli). Thus, capsules containing the QCHI derivative with the highest DS are shown to be the most efficient to kill E. coli while retaining their biocompatibility toward myoblast cells, which suggests their potential as drug carriers able to combat bacterial infections. [source] Carbon Nanotubes on Polymeric Microcapsules: Free-Standing Structures and Point-Wise Laser OpeningsADVANCED FUNCTIONAL MATERIALS, Issue 18 2010Alexey M. Yashchenok Abstract Single-wall carbon nanotubes modified by anionic polyelectrolyte molecules are embedded into the shells of microcapsules. Carbon nanotubes serve as rigid rods in a softer polymeric capsule, which forms a free-standing shell upon treatment with glutaraldehyde and subsequent drying. The embedded carbon nanotubes exhibit a broad absorption in the UV,near-infrared part of the spectrum, and that allows point-wise activation and opening of the microcapsules by laser. Raman signal analysis shows changes of carbon-nanotube-specific lines after high-power laser irradiation, which is characteristic of the formation of disordered carbonlike structures. These polyelectrolyte/carbon nanotube composite capsules represent a novel light-addressable type of microcontainers. [source] Restoration of Conductivity with TTF-TCNQ Charge-Transfer SaltsADVANCED FUNCTIONAL MATERIALS, Issue 11 2010Susan A. Odom Abstract The formation of the conductive TTF-TCNQ (tetrathiafulvalene,tetracyanoquinodimethane) charge-transfer salt via rupture of microencapsulated solutions of its individual components is reported. Solutions of TTF and TCNQ in various solvents are separately incorporated into poly(urea-formaldehyde) core,shell microcapsules. Rupture of a mixture of TTF-containing microcapsules and TCNQ-containing microcapsules results in the formation of the crystalline salt, as verified by FTIR spectroscopy and powder X-ray diffraction. Preliminary measurements demonstrate the partial restoration of conductivity of severed gold electrodes in the presence of TTF-TCNQ derived in situ. This is the first microcapsule system for the restoration of conductivity in mechanically damaged electronic devices in which the repairing agent is not conductive until its release. [source] Nanocomposite Microcontainers with High Ultrasound SensitivityADVANCED FUNCTIONAL MATERIALS, Issue 7 2010Tatiana A. Kolesnikova Abstract A water suspension of nanocomposite microcapsules with embedded ZnO nanoparticles in the capsule shell is reported. The microcapsule morphology is characterized by confocal microscopy, TEM, SEM, and AFM before and after ultrasound treatment. A remarkably high capsule sensitivity to ultrasound is evidenced, and it is observed to grow with increasing number of ZnO nanoparticle layers in the nanocomposite shell. This effect is correlated with the mechanical properties of microcapsules measured with AFM. [source] Hierarchical Nanomaterials: Smart Microcapsules Encapsulating Reconfigurable Carbon Nanotube Cores (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 5 2010Mater. Heavy metal ion removal is demonstrated using carbon nanotubes (CNTs) surrounded by iron oxide microcapsules by W. S. Choi on page 820. The CNTs conglomerate and form a core inside the capsule upon exposure to high temperature, while they scatter when they are subjected to mild sonication. These hierarchical structures can capture lead and chromium ions, which can later be desorbed by exposure to low pH conditions. [source] Smart Microcapsules Encapsulating Reconfigurable Carbon Nanotube CoresADVANCED FUNCTIONAL MATERIALS, Issue 5 2010Won San Choi Abstract The encapsulation of carbon nanotubes (CNTs) to form a reconfigurable conglomerate within iron oxide microcapsules is demonstrated. The individual CNTs conglomerate and form a core inside the capsule upon exposure to high temperature, while they scatter when subjected to mild sonication at low pH. The assembly/disassembly of CNTs within the capsule was reversible and could be repeated by alternate heating and sonication. Also, the fabrication protocol could be used for the generation of various multifunctional hollow structures. To test the feasibility of using the capsules in real applications, the capacity of the capsules as a heavy metal ion remover was explored. The resulting capsules showed an excellent ability to remove lead and chromium ions. In addition, desorption of the metal ions adsorbed on the CNTs could be induced by exposure to low pH. Thus, encapsulated CNTs might be a recyclable, environmentally friendly agent for the removal of heavy metal ions. [source] Preparation of phosphorus and carbohydrate microcapsules for manipulating dietary C : P ratio for aquatic suspension-feedersFRESHWATER BIOLOGY, Issue 2 2003Daniel A. Kreeger SUMMARY 1.,Dietary phosphorus can be limiting for aquatic animals such as suspension-feeders. However, our understanding has been limited by the difficulty of manipulating dietary P without altering other aspects of food quality. We microencapsulated various forms of bioavailable P with carbohydrate to manipulate dietary C : P ratio for suspension-feeders. 2.,Calcium phosphate, sodium hexametaphosphate, sodium tripolyphosphate and tetrasodium pyrophosphate were each mixed with a concentrated solution of a carbohydrate base (either maltodextrin or potato starch) and microencapsulated using an interfacial polymerisation technique. Each of the 10 types of capsules produced had a particle size ideal for suspension-feeders (3,10 ,m). 3.,Leakage rates were low (<12% of capsule weight per day). Relative enzymatic breakdown in vitro by carbohydrases (amylase or cellulase) was similar among the 10 capsule types and was always at least 15 times the comparable leakage rate. 4.,Release of dissolved P from enzyme-treated capsules varied depending on capsule P content. Liberation of P from capsules prepared from 20% w/w sodium hexametaphosphate in maltodextrin (molar C : P = 1.8) was three times greater than all other types, and this combination appears most suitable as a dietary supplement for zooplankton. 5.,Although P content and capsule integrity were greatly influenced by choice of carbohydrate, choice of P compound, and the mixing ratio of the two, P-rich artificial microparticles can be produced that have low leakiness, high digestibility, and a physical size suitable for aquatic suspension-feeders. Therefore, microcapsules represent promising tools for manipulating dietary C : P for suspension feeders. [source] Self-Healing Materials: A Facile Strategy for Preparing Self-Healing Polymer Composites by Incorporation of Cationic Catalyst-Loaded Vegetable Fibers (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 14 2009Mater. Discontinuous sisal fibers carrying extremely active (C2H5)2O·BF3 are embedded in epoxy matrix together with epoxy monomer-loaded microcapsules to fabricate self-healing composite based on the healing mechanism of cationic chain polymerization. This approach, described by D. S. Xiao et al. on page 2289, skips the encapsulation of high activity chemicals, reducing the risk of their deactivation during handling. It provides a facile strategy for making extrinsic self-healing polymeric materials. [source] A Facile Strategy for Preparing Self-Healing Polymer Composites by Incorporation of Cationic Catalyst-Loaded Vegetable FibersADVANCED FUNCTIONAL MATERIALS, Issue 14 2009Ding Shu Xiao Abstract A two-component healing agent, consisting of epoxy-loaded microcapsules and an extremely active catalyst (boron trifluoride diethyl etherate, (C2H5)2O,·,BF3)), is incorporated into epoxy composites to provide the latter with rapid self-healing capability. To avoid deactivation of the catalyst during composite manufacturing, (C2H5)2O,·,BF3 is firstly absorbed by fibrous carriers (i.e., short sisal fibers), and then the fibers are coated with polystyrene and embedded in the epoxy matrix together with the encapsulated epoxy monomer. Because of gradual diffusion of the absorbed (C2H5)2O,·,BF3 from the sisal into the surrounding matrix, the catalyst is eventually distributed throughout the composites and acts as a latent hardener. Upon cracking of the composites, the epoxy monomer is released from the broken capsules, spreading over the cracked planes. As a result, polymerization, triggered by the dispersed (C2H5)2O,·,BF3, takes place and the damaged sites are rebonded. Since the epoxy,BF3 cure belongs to a cationic chain polymerization, the exact stoichiometric ratio of the reaction components required by other healing chemistries is no longer necessary. Only a small amount of (C2H5)2O,·,BF3 is sufficient to initiate very fast healing (e.g., a 76% recovery of impact strength is observed within 30,min at 20,°C). [source] Inside Front Cover: Novel Engineered Ion Channel Provides Controllable Ion Permeability for Polyelectrolyte Microcapsules Coated with a Lipid Membrane (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 2 2009Mater. In their Full Paper on page 201, Donald Martin and co-workers describe the covering of polyelectrolyte microcapsules with a lipid bilayer that incorporates a novel engineered ion channel to provide a functional capability to control transport across the microcapsule wall. The cover image shows atomic-force microscopy images of these 8-layer polyelectroctrolyte capsules recorded using tapping mode in an aqueous environment. The capsules can be seen to collapse in a folded manner, with an occasional wrinkle that "absorbs" the extra surface area when flattening the spherical surface. [source] Novel Engineered Ion Channel Provides Controllable Ion Permeability for Polyelectrolyte Microcapsules Coated with a Lipid MembraneADVANCED FUNCTIONAL MATERIALS, Issue 2 2009Andrew R. Battle Abstract The development of nanostructured microcapsules based on a biomimetic lipid bilayer membrane (BLM) coating of poly(sodium styrenesulfonate) (PSS)/poly(allylamine hydrochloride) (PAH) polyelectrolyte hollow microcapsules is reported. A novel engineered ion channel, gramicidin (bis-gA), incorporated into the lipid membrane coating provides a functional capability to control transport across the microcapsule wall. The microcapsules provide transport and permeation for drug-analog neutral species, as well as positively and negatively charged ionic species. This controlled transport can be tuned for selective release biomimetically by controlling the gating of incorporated bis-gA ion channels. This system provides a platform for the creation of "smart" biomimetic delivery vessels for the effective and selective therapeutic delivery and targeting of drugs. [source] Preparation of Protamine,Titania Microcapsules Through Synergy Between Layer-by-Layer Assembly and Biomimetic MineralizationADVANCED FUNCTIONAL MATERIALS, Issue 1 2009Yanjun Jiang Abstract A novel approach combining layer-by-layer (LbL) assembly with biomimetic mineralization is proposed to prepare protamine,titiania hybrid microcapsules. More specifically, these microcapsules are fabricated by alternative deposition of positively charged protamine layers and negatively charged titania layers on the surface of CaCO3 microparticles, followed by dissolution of the CaCO3 microparticles using EDTA. During the deposition process, the protamine layer induces the hydrolysis and condensation of a titania precursor, to form the titania layer. Thereafter, the negatively charged titania layer allows a new cycle of deposition step of the protamine layer, which ensures a continuous LbL process. The morphology, structure, and chemical composition of the microcapsules are characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared, and X-ray photoelectron spectroscopy. Moreover, these protamine,titania hybrid microcapsules are first employed as the carrier for the immobilization of yeast alcohol dehydrogenase (YADH), and the encapsulated YADH displays enhanced recycling stability. This approach may open a facile, general, and efficient way to prepare organic,inorganic hybrid materials with different compositions and shapes. [source] Self-Rupturing and Hollow Microcapsules Prepared from Bio-polyelectrolyte - Coated Microgels,ADVANCED FUNCTIONAL MATERIALS, Issue 4 2007G. De, Geest Abstract This paper reports on microcapsules obtained by layer-by-layer deposition of bio-polyelectrolyte multilayers at the surface of biodegradable dextran microgels. The behavior of the layer-by-layer coating upon degradation of the microgel core strongly depends on the bio-polyelectrolytes used. Two types of microcapsules, "self-rupturing" microcapsules and "hollow" microcapsules, are presented. Self-rupturing microcapsules are obtained when the swelling pressure of the degrading microgel core is strong enough to rupture the surrounding bio-polyelectrolyte membrane. Self-rupturing microcapsules could be of interest as a pulsed drug delivery system. Hollow microcapsules are obtained after applying multiple layers of bio-polyelectrolyte that can withstand the swelling pressure of the degrading microgel core. Biomacromolecules (such as albumin and dextran) spontaneously accumulate in the hollow microcapsules prepared from dex-HEMA microgels, which could be of interest for drug-encapsulation purposes. [source] Enhanced heat transfer analysis of latent functionally thermal fluidHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 6 2004Fengwu Bai Abstract A physical model has been developed to analyze the enhanced heat transfer process of the latent functionally thermal fluid with microencapsulated phase-change material. The problem is solved by the combination of the finite difference method and the moving heat source method. The calculated results reveal that putting the phase-change microcapsules into the fluids can enhance the heat transfer capabilities of the mixture. The effects of capsule radius and concentration of particles are numerically predicted. The numerical results provide the theoretical basis for the application and design of the latent functionally thermal fluid. © 2004 Wiley Periodicals, Inc. Heat Trans Asian Res, 33(6): 383,392, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20025 [source] Microcapsules Containing a Biomolecular Motor for ATP Biosynthesis,ADVANCED MATERIALS, Issue 15 2008Qiang He Abstract Over the past two decades, advances in modern biology and nanotechnology have enabled a rapid development in the design and building of biomimetic functional materials. ATP synthase is one of the most extensively studied molecular machines because it can be used as a rotary motor in the design of novel nanodevices and it can also continuously synthesize ATP in an artificial environment. A lot of research efforts have focused on assembling ATP synthase in biomimetic systems so that a complex cellular process can be constructed in a controllable manner. As we summarize here, layer-by-layer assembled microcapsules have proved to be a suitable cellular mimetic structure, which can be applied for engineering active biomimetic systems with a cellular process. An added benefit is that these assembled microcapsules can be used as bioenergy containers and thus ATP supply on demand. [source] Soluble Microcapsules Assembled Stepwise from Weak Polyelectrolytes Using Acid-Decomposable Cores,ADVANCED MATERIALS, Issue 11 2003C.-Y. Gao Decomposable microcapsules with tunable permeability, loading, and release properties,with potential applications as chemical reservoirs and for controlled drug release,have been fabricated by assembly of weak polyelectrolytes on melamine formaldehyde templates followed by removal of the cores at low pH by precise control of the time of acid treatment. The Figure shows capsules before (left) and after (right) treatment with 0.1 M HCl. [source] Smart polymeric coatings,recent advancesADVANCES IN POLYMER TECHNOLOGY, Issue 1 2007W. Feng Abstract There is an ever-growing number of developments that aim to bring novel functionalities to polymer-coating systems with nanotechnology being one of them. This article will cover recent advances in the field of smart polymeric structures that are used in protective coatings in terms of stimulus and response, sensing mechanisms, and current or potential applications. Such structures are commonly based on polymers modified through organic or inorganic additives. Emphasis is placed on smart sensors used for detecting the onset of corrosion on polymer coated ferrous and nonferrous substrates. Examples of self-healing and repair through the action of microcapsules are also presented. © 2007 Wiley Periodicals, Inc. Adv Polym Techn 26:1,13, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20083 [source] Orientational disruption of codling moth, Cydia pomonella (L.) (Lep., Tortricidae), by concentrated formulations of microencapsulated pheromone in flight tunnel assaysJOURNAL OF APPLIED ENTOMOLOGY, Issue 9-10 2005L. L. Stelinski Abstract:, The effects of two formulations of microencapsulated pheromone (CheckMate CM-F), containing 14.3% (E,E)-8,10-dodecadien-1-ol (codlemone), on the behaviour of the male codling moth, Cydia pomonella (L.), were evaluated in a flight tunnel after several periods of formulation ageing. The two treatments of CheckMate CM-F evaluated consisted of the label-recommended field rate of 50 g active ingredient (a.i.)/ha diluted in: (1) a standard 1000 l of water (low concentration 0.05 g/l), and (2) a low volume of 100 l of water (high concentration 0.5 g/l). The low-concentration treatment was formulated by diluting 0.071 ml of CheckMate CM-F in 500 ml of water and the high-concentration treatment contained 0.71 ml of CheckMate CM-F in 500 ml of water. Wax-paper strips (2.1 × 20 cm) were treated at 0.06 ml of solution/cm2. The mean (±SE) number of CheckMate CM-F microcapsules adhering to treated wax-paper strips in the high-concentration treatment (398 ± 38) was sevenfold greater than that (57 ± 5) counted on wax-paper strips treated with the low concentration. Both low- and high-concentration treatments prevented anemotactic orientation of male codling to an adjacent 0.1 mg codlemone lure for up to 24 h after application. These moths flew out of the release cages, but exhibited erratic and short flights not restricted to any plume and ending at the tunnel walls or the floor. This occurred with approximately 60 and 400 microcapsules per wax-paper strip in the low- and high-concentration treatments, releasing codlemone at approximately 0.15 and 1.5 ,g/h respectively. After 2 days of ageing, the low-concentration treatment no longer interfered with the ability of males to find the codlemone lure. However, the number of males contacting the lure was significantly reduced for up to 6 days with the high-concentration treatment relative to the control and low-concentration treatments. The high-concentration treatment no longer impeded normal orientational flight after 2,6 days of ageing; but, it diverted males from the codlemone lure by causing them to land on the adjacent treated wax-paper strips. This occurred at a release rate of approximately 0.7 ,g codlemone/h from approximately 400 microcapsules per wax-paper strip distributed as clumps of approximately 30 microcapsules per 14 mm2. We suggest that an initial but short-lived disruption mechanism like camouflage is followed by a longer period of false-plume following to clumps of microcapsules. The low-volume, concentrated application method for disseminating pheromone microcapsules warrants further investigation for moth codling, as well as other pests because this approach may improve the efficacy without the need for increasing the field application rate. [source] In vitro evaluation of the activity of microencapsulated carvacrol against Escherichia coli with K88 piliJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2009Q. Wang Abstract Aims:, The aim of the current study is to develop encapsulation of essential oils for oral delivery to the small intestine of pigs in order to retain their antimicrobial activity. Methods and Results:, Carvacrol was used as a model essential oil and successfully encapsulated in microcapsules made from Ca-alginate hydrogel using an emulsion,extrusion technology with high encapsulation efficiency. This encapsulation method did not compromise the antimicrobial activity when tested against Escherichia coli K88 in a culture medium, as well as in a simulated gastrointestinal model. In the simulated gastrointestinal model, <20% of encapsulated carvacrol was released in the simulated gastric fluid; the rest was nearly completely released in the intestinal fluid after 6 h of incubation. Conclusions:, Encapsulation in Ca-alginate microcapsules could effectively reduce the early absorption of carvacrol in the upper gastrointestinal tract after oral administration, therefore, retains its potential antibacterial activity for the small intestine. Significance and Impact of the Study:, The developed encapsulation method is expected to be suitable for encapsulation of other essential oils. The results from this study would increase the likelihood of success in the application of essential oils as antimicrobial agents for controlling enteric diseases in pigs. [source] | ||||||||||||||||||||||||||||||||||