The current work presents an unprecedented direct observation of macropore formation in the spontaneous self-assembly process to obtain hierarchical meso/macroporous metal oxides made possible with the help of an unusual titanium alkoxide. PMID:20967374

One of the major concerns during gas tungsten arc (GTA) welding of cast magnesium alloys is the presence of large macroporosity in weldments, normally thought to occur from the presence of gas in the castings. In this study, a double-sided GTA welding process was adopted to join wrought magnesium AZ91D alloy plates. Micropores were formed in the weld zone of the first side that was welded, due to ...

During the past quarter, the authors carried out a systematic analysis of the macropore structure of chars produced from Illinois No. 6 coal. Digital images of char particle cross-sections were acquired and analyzed to measure the size distribution of the macropores. The measured macropore size distributions depended strongly on both ...

FREQUENTLY ASKED QUESTIONS FAQ161 GYNECOLOGIC PROBLEMS [PDF format] Understanding Abnormal Pap Test Results What is a Pap test? What causes abnormal Pap test results? ...

Saturated macropore flow is the dominant hydrological process in tropical and subtropical hilly watersheds of northeast India. The process of infiltration into saturated macroporous soils is primarily controlled by size, network, density, connectivity, saturation of surrounding soil matrix, and depthwise distribution of macropores. To ...

A technique for the formation of pore arrays with high aspect ratios by electrochemical etching of n-type silicon wafers in hydrofluoric acid is presented. New devices such as silicon based capacitors or photonic bandgap materials for the infrared spectral range are fabricated based on this new technology.

Hierarchical organosilicate sorbents were synthesized which possess structure on two length scales: macropores of approximately 1microm lined by mesopores (35-45A). The incorporation of macropores provides enhanced flow-through characteristics over purely mesoporous materials, thereby reducing back pressure when used in column formats. ...

Single-site Ti-containing hierarchical macroporous silica with mesoporous frameworks (Ti-MMS) was successfully prepared by a solvent evaporation method using organic surfactant and poly(methyl methacrylate) (PMMA) colloidal crystals as the template. The formation of a well-defined macroporous structure composed of mesoporous silica ...

First hierarchical titanium phosphate (TiPO) materials with multiple porosities of different lengths (meso-macroporous and meso-macro-macroporous) were synthesized by the self-formation process. The further tuning of the porous hierarchy by using the poly(ethylene oxide) surfactant technique was demonstrated. The ...

Hierarchical periodic titania nanostructures composed of a macroporous crystalline scaffold and mesoporous titania were prepared by confined synthesis. The strategy for the generation of these hierarchical structures involves preparation of inverse opal titania layers and subsequent filling of the interstitial macroporous voids with surfactant-containing ...

... abnormalities. The lethality for the homozygotes occurs prior to formation of mature peripheral nerves. To test the effect of loss ...

The 75-page report describes and analyzes the occurrences of multiple zones of abnormal formation pressure that were encountered in nine wells drilled in the Navarin basin. The report provides a discussion of the abnormal pressure response on wireline logs and drilling parameters, and a comparison between direct and indirect pressure ...

Mesoporous SiO(2)/TiO(2)/Fe(2)O(3) particles containing macropores of about 50 nm in diameter have been prepared by an aerosol process using cetyltrimethylammonium bromide (CTAB) as a templating agent. In contrast to the traditional templating effect of CTAB to form ordered mesoporous silicas, the morphology here is vastly different due to the presence of precursor iron salts. ...

To develop a highly active calcium oxide high-temperature desulfurization sorbent, a method of preparation of macroporous calcium oxides from lime was studied. This method is composed of two steps: swelling of the lime and calcination of the swelled sample. Swelling occurred when lime was exposed to the vapor of acetic acid. The swelling resulted from calcium acetate ...

Limestone is a very important material as a high temperature desulfurization sorbent: limestone is used for in-bed SO{sub 2} capture in fluidized bed combustors of coal and can be used in coal gasifiers for the in-bed removal of H{sub 2}S. In order to develop a highly active calcium oxide high-temperature desulfurization sorbent, macroporous calcium oxides were directly ...

... aortic arch is an abnormal formation of the aorta, the large artery that carries blood from the ... defects that affect the development of the baby�s aorta in the womb. These defects cause an abnormal ...

1425 ... www.nlm.nih.gov ... As a fetus develops, the formation of the internal and/or external sexual organs may be abnormal. This abnormal ...

The MEMS silicon-micro-machining is the main MEMS technology, which includes the surface-silicon-micro-machining and the bulk-silicon-micro-machining technology; however the bulk-silicon micro-machining technology has a wide application. In this paper, the formation procession of electron multiplier on n-type Silicon substrate by bulk-silicon-micro-machining technology was ...

This review summarises the major developments of macroporous bioceramics used mainly for repairing bone defects. Porous bioceramics have been receiving attention ever since their larger surface area was reported to be beneficial for the formation of more rigid bonds with host tissues. The study of porous bioceramics is important to overcome the less ...

Hierarchically structured spongy meso-macroporous aluminosilicates with high tetrahedral aluminum content were synthesized from a mixture of single molecular alkoxide precursor, (sec-BuO)(2)-Al-O-Si(OEt)(3), already containing Si-O-Al bonds, and a silica coreactant, tetramethoxysilane (TMOS). The spontaneous byproduct templated macroporous structure ...

The environmentally friendly ionic liquid N-(2-hydroxyethyl)ammonium formate works as a reaction medium, reducing and templating agent in the mild microwave synthesis (5 min, 80 degrees C) of a macroporous silver framework from AgNO(3). PMID:19209309

The process of trench formation in photo-electrochemical etching of n-type Si (1 0 0) has been studied as dependent on the normalized etching current density j/jPS and on the line seed period a. Experiments were performed on n-type Si (1 0 0) samples with resistivity ? = 5 and 15 ? cm. V-shaped grooves with a period a = 4-13 �m, fabricated on the sample surface, were used as ...

Hierarchically patterned macroporous TiO2 structures can be fabricated via the spontaneous self-assembly of TiO2 nanoparticles prepared using a mixture of 1-octadecene (ODE) and an ODE-immiscible 1-alkyl-3-methylimidazolium-based ionic liquid as the reaction medium. A study of the influence of side chain lengths of ionic liquids (n = 4, 8, or 16) reveals that this parameter ...

Illumination lowers the rate of porous-layer formation under galvanostatic polarization, so that the linear and parabolic kinetics found in the dark is transformed to linear kinetics. Under the effect of light, oxidation of silicon to the divalent state is the predominant reaction; this promotes formation of a more porous structure because of inhibition of ...

Macroporous hydrogels may have direct applications in regenerative medicine as scaffolds to support tissue formation. Hydrogel microspheres may be used as drug-delivery vehicles or as building blocks to assemble modular scaffolds. A variety of techniques exist to produce macroporous hydrogels and hydrogel microspheres. A subset of ...

A ureolytic biodeposition treatment was applied to five types of limestone in order to investigate the effect of pore structure on the protective performance of a biogenic carbonate surface treatment. Protective performance was assessed by means of transport and degradation processes, and the penetration depth of the treatment was visualized by microtomography. Pore size governs bacterial ...

We carried out a study on the change in pore wall thickness depending on the current density in p-type silicon. We attempted the formation of a uniform macropore or nanorod array with a high aspect ratio in p-type silicon by electrochemical etching through the optimization of the hydrogen fluoride (HF)/organic electrolyte composition and the design of the ...

... and abnormally pressured reservoirs has long been recognized as a function of the formation fluid properties and the reservoir rock parameters. ...

Mesoporous (2.0--50.0 nm pore diameter) and macroporous (50.0 nm on up) materials have been the basis of my studies. These materials, for many years, possessed large pore size distributions. Recently, however, it has been possible to synthesize both mesoporous and macroporous materials that possess highly ordered uniform pores throughout the material. ...

Print Version Interactive Discussion EGU Hydrol. Earth Syst. Sci. Discuss., 3, 229�270, 2006 www of the terrain through macropore structures, fractures and discon- tinuity of permeability. Although field of storing and releasing large quantities of water. Limestone formations are strongly10 fractured

The near-IR light absorption oscillations in 2D macroporous silicon structures with microporous silicon layers, CdTe surface nanocrystals and SiO2 nanocoatings are investigated. The electro-optical effect was taken into account within the strong electric field approximation. Well-separated oscillations with giant amplitude were observed in the spectral ranges of surface level ...

Ultrasonic spray pyrolysis has been used as a facile aerosol route to macroporous SiO(2) particles using simple inorganic salts as a pore template and colloidal SiO(2) as building blocks to the larger porous particles. As we found, the use of template salts with low melting points was vital to macroporous particle synthesis, as a dynamic droplet phase can ...

Methods commonly used for covalent immobilization of single stranded DNA have been applied to several solid supports (Sephadex G-25 and Cellex 410) as well as to a number of macroporous materials (Sepharose C1-6B, C1-2B; Sephacryl S-500 and S-1000). Coupling efficiencies and stability of covalently bound DNA are compared for both classes of materials. The yields of the ...

A variety of sub-10?nm nanoparticles are successfully prepared by crosslinking of polystyrene-b-poly(1,3-butadiene) (PS-b-PB) and polystyrene-b-poly(4-vinyl pyridine) (PS-b-P4VP) block copolymer micelles and inverse micelles. Among them, the core-crosslinked PS-b-PB micelles can self-assemble into ultrathin (< 10?nm) macroporous (pore size <1?�m) membranes in a facile ...

Hierarchically 2D/3D mesoporous-macroporous bioactive glasses (MMBG) with good molding capabilities and compressive modulus were synthesized by sol-gel method and evaporation-induced self-assembly process in the presence of both nonionic triblock copolymers, EO(70)PO(20)EO(70) (P123) or EO(100)PO(65)EO(100) (F127), templates and methyl cellulose template. P123 or F127 acts as ...

Thesis. Several macroporous polystyrene, polyacrylate, and other macroporous resins are shown to be suitable as column packing materials for gas chromatographic separation of gases. Retention times of gases were determined and several complex gas mixtures were separated on columns packed only with macroporous resins. (DLC)

Qaidam basin is a Mesozoic and Cenozoic inland oil basin where the abnormal formation pressure is as developed as in many offshore regions. The abnormal formation pressures are found at depths below 3200 m in relatively depressed regions. Their pressure gradients are from 0.14 to 0.22 atm/m. The causes of ...

A tool for the formation of holes without extracting the soil comprises a body having a cylindrical calibrating portion, coaxial portions with surfaces for the compaction of the soil and radii decreasing stepwise in the direction away from the calibrating portion, and terminating in an end piece. The body has also transition portions with surfaces for the compaction of the ...

Three-dimensionally (3D) ordered macroporous (3DOM) iron oxides with nanovoids in the rhombohedrally crystallized macroporous walls were fabricated by adopting the dual-templating [Pluronic P123 and poly(methyl methacrylate) (PMMA) colloidal microspheres] strategy with ferric nitrate as the metal precursor in an ethanol or ethylene glycol and methanol ...

We present results of experimental studies on the formation of gas hydrates (clathrates) at conditions of geophysical interest. Clathrate hydrates formed by a reaction of gas at ice Ih surfaces are always found to be mesoporous to macroporous with pores sizes between 100 to 400 nm and pore volumes of approximately 25-40% for CH4, Ar and N2 hydrate, and ...

Abnormal grain growth was found in sintered Nd-Fe-B magnets which are made from powder milled after hydrogen decrepitation. The abnormal grain size in the magnets sintered at 1000 {degree}C for 1.5 h was as large as 400 {mu}m. The formation of abnormally large grains reduced the magnetic properties. As sintering ...

Soil and crop management practices have been found to modify soil structure and alter macropore densities. An ability to accurately determine soil hydraulic parameters and their variation with changes in macropore density is crucial for assessing potential contamination from agricultural chemicals. This study investigates the consequences of using ...

In this paper, we will thoroughly review a novel and versatile self-formation phenomenon that can be exploited to target porous hierarchies of materials without need of any external templates only on the basis of the chemistry of metal alkoxides and alkylmetals. These hierarchically porous materials have unique structures, which are made of either parallel funnel-like/straight ...

A variety of calcium phosphates have been used for bone tissue-engineering applications. We developed porous hydroxyapatite (HAp) ceramics by firing green compacts consisting of spherical carbon beads and HAp fiber. The apatite-fiber scaffold (AFS) forms a three-dimensional network of fibers with two different pore sizes (micro- and macropores). In this study, we investigated ...

It is well established that scaffolds for applications in bone tissue engineering require interconnected pores on the order of 100 microm for bone in growth and nutrient and waste transport. As a result, most studies have focused on scaffold macroporosity (>100 microm). More recently researchers have investigated the role of microporosity in calcium phosphate -based scaffolds. Osteointegration ...

Porous hydroxyapatite (HA) scaffolds have been intensively studied and developed for bone tissue engineering, but their mechanical properties remain to be improved. The aim of this study is to prepare HA-based composite scaffolds that have a unique macroporous structure and special struts of a polymer/ceramic interpenetrating composite and a bioactive coating. A novel ...

An important consideration in bone regeneration is the need for expedited neovascularization within the defect site. Formation of a vascular network is critical for cell viability and normal function leading to tissue regeneration, but spontaneous angiogenesis is too slow to yield sufficient vessel formation. In this pilot study, human umbilical cord blood ...

version Email this page to a friend Share Vascular ring is an abnormal formation of the aorta, the large artery that carries blood from the heart to the rest of the body. It is a...

a different texture than normal skin. Striae may also occur as a result of abnormal collagen formation, or a result of medications or chemicals that interfere with collagen...

To study the occurrence of microgravity-induced abnormalities during avian embryonic development " To examine the differences in the formation of avian ...

This is a picture of diffuse, cutaneous mastocytosis. Abnormal collections of cells in the skin (mast cells) produce this rash. Unlike bullous mastocytosis, rubbing will not lead to formation ...

The driving force behind the development of this research project has been the increasing concerns about the detrimental effects of high carbon carryover into combustion ash. Without the carbon, combustion ash can be utilized in cement industry avoiding environmental implications in landfill operations. Because the carbon surfaces have been structurally altered while passing through the combustor, ...

A microvascular network is critical for the survival and function of most tissues. We have investigated the potential of neural progenitor cells to augment the formation and stabilization of microvascular networks in a previously uncharacterized three-dimensional macroporous hydrogel and the ability of this engineered system to develop a functional ...

A microvascular network is critical for the survival and function of most tissues. We have investigated the potential of neural progenitor cells to augment the formation and stabilization of microvascular networks in a previously uncharacterized three-dimensional macroporous hydrogel and the ability of this engineered system to develop a functional ...

Technological development has made it possible to estimate accurately and to control abnormal pressures; this information can be used to prevent blowouts. In abnormally pressured formations, the pore pressure of the fluids exceeds the pressure that is exerted by a column of saltwater extending to the surface (0.465 psi/ft). The upper ...

Facial dysmorphism associated with distinctive spine abnormalities has been encountered in a girl and her mother. A three-dimensional reformatted spinal computed tomography scan showed a combination of distinctive abnormalities such as failure of anterior formation of the vertebral bodies, malsegmentation, and Forestier disease. ...

The possibility of using macroporous cation exchange resins for the purification of uranium from thorium relevant to the final purification of uranium after reprocessing thorium breeder fuel was explored. Two macroporous cation exchange resins were studie...

Scaling hydraulic properties of a macroporous soil Binayak P. Mohanty U.S. Salinity Laboratory, Riverside, California Abstract. Macroporous soils exhibit significant differences in their hydraulic properties for different pore domains. Multimodal hydraulic functions may be used to describe

Quantitative relationships between soil structure, especially macropore characteristics, and soil hydraulic properties are essential to improving our ability to predict flow and transport in structured soils. The objectives of this study were to quantitatively relate macropore characteristics to sat...

Macropore transport of chemicals in soil often causes unexpected contamination of groundwater. The effect of soil structure on the functions of various sized macropores was assessed, investigating transport of nonreactive bromide (Br) under matric heads of 0, -2, -5, and -10 cm using undisturbed soi...

Park J-C, So S-S, Jung I-H, Yun J-H, Choi S-H, Cho K-S, Kim C-S. Induction of bone formation by Escherichia coli-expressed recombinant human bone morphogenetic protein-2 using block-type macroporous biphasic calcium phosphate in orthotopic and ectopic rat models. J Periodont Res 2011; doi: 10.1111/j.1600-0765.2011.01390.x. � 2011 John Wiley & Sons ...

Accurate formation fracture gradient prediction in abnormally pressured wells is one of the most critical considerations involved in planning a successful drilling operation. Shallow abnormal pressure, coupled with deep geologic objectives, requires an accurate fracture gradient prediction to insure casing setting depths are correctly ...

... Accession Number : ADD405203. Title : Macroporous resins for sorption of organics from water and gases from air. Corporate ...

Beaufort Sea drilling is complicated by abnormal formation pressures encountered at both deep and shallow depths. Dome has devised a technique known as kick tolerance to supplement standard existing methods of abnormal pressure prediction and detection to determine a safe formation fluid influx level.

The importance of pure-phase titanium oxide materials as catalysts, sensors, and photonic band-gap materials has been growing steadily. Recently, more attention has been focused on nanostructured titanium oxide showing controlled and periodic porosity on a nanometric scale. The nanocrystal size control of porous nanostructured titanium oxide in an anatase form is a crucial step for the organic ...

In this study, silver nanoparticles were formed on a natural macroporous matrix, the stem of rice-paper plant, by reducing Ag+ in aqueous solution through in situ processing without using any other stabilizers. The pores of the matrix, with their size of about 100 �m, were thought to act as reaction compartments for the nucleation and growth of silver nanoparticles, and the ...

In this study agarose-alginate scaffolds are synthesized using cryogelation technology in different formats like monolith, sheet, discs, and beads, and show amiable mechanical strength like soft tissue properties and high interconnected macroporous degradable architecture. In cell-material interactions, fibroblast (NIH-3T3) cells showed good adherence and ...

A series of temperature-sensitive poly(N-isopropylacrylamide) (PNIPA) hydrogels with large pore size and fast response were prepared by carrying out polymerizations in aqueous sodium chloride solutions with different concentrations. In comparison with conventional PNIPA hydrogels, the PNIPA gels thus prepared have remarkably larger swelling ratios below their lower critical solution temperature ...

A method is given for coating a macroporous Ni tube with a layer of microporous Ni in order to obtain a diffusion barrier for isotope separation processes, e.g. the separation of UF/sub 6/. The tube, having pores of 1.3 microns, is interiorly coated with a 0.1 to 0.4 mm thick layer of a paste which consists of 50 vol% of Ni formate and 50 vol% of ...

Macroporous films with highly ordered pore patterns have many potential applications. Some examples include microstructured electrode surfaces, photonic band gap materials and filters for cell sorting and bio-interfaces. In this dissertation we discuss a "moist-casting" method to prepare hexagonally-ordered macroporous films with pore sizes in the range of ...

We report the formation of a three-dimensionally ordered array of air bubbles of monodisperse pore size in a polymer film through a templating mechanism based on thermocapillary convection. Dilute solutions of a simple, coil-like polymer in a volatile solvent are cast on a glass slide in the presence of moist air flowing across the surface. Evaporative cooling and the ...

The construction of adsorption sites for mercury(II) by chemical immobilization of ?-cyclodextrin and its functional derivatives on a surface of macroporous amorphous silica is proposed. It is shown that the adsorption of mercury(II) is adequately described by the Langmuir isotherm equation for monolayer adsorption on localized sites of energetically homogeneous surfaces. It ...

Porous polysilsesquioxane gels derived from sol-gel systems based on trifunctional silanes are reviewed. Although it is well known that trifunctional silanes possess inherent difficulties in forming homogeneous gels, increasing attention is being paid on these precursors and resultant porous polysilsesquioxanes because of hydrophobicity, functionality, and versatile mechanical properties. Much ...

Preferential flow in agricultural regions poses a serious environmental threat by allowing chemicals to bypass the soil matrix and to be channeled into ground water. Although a long-known phenomenon, our understanding of and ability to predict macropore flow and transport remain far from complete. To analyze the processes that control macropore flow in ...

The effects of two aminoglycoside antibiotics on cultured astrocyte organelles were investigated in rat, sheep, and human cultured astrocytes using transmission electron microscopy. Marked changes in mitochondrial shapes were observed in cultured or subcultured astrocytes obtained from three species, including humans. As well, new types of organelles were observed: (i) numerous concentric ...

The microstructural characteristics of ultra-high carbon hyper-eutectoid Fe-C and Fe-C-Cu experimental steels have been examined after isothermal transformation in a range just beneath the eutectoid temperature. Particular attention was paid to the formation of so-called abnormal ferrite, which refers to coarse ferrite grains which can form, in ...

Transport at the field scale of agricultural chemicals through structured soils to groundwater and surface waters is often strongly governed by flow through macropores. In the Netherlands, the ANIMO nutrient and PEARL pesticide leaching models are used for policy evaluations and policy support at field, regional and national scales. Both models apply the SWAP model to provide ...

Abnormally large grains have been observed in Al-Mg alloy AA5182 sheet material after forming at elevated temperature, and the reduced yield strength that results is a practical problem for commercial hot-forming operations. The process by which abnormal grains are produced is investigated through controlled hot tensile testing to reproduce the ...

Systems driven far from equilibrium have a remarkable tendency to produce very ordered structures. Such ordered structures have been observed in many a situation where the material subjected to an external perturbing field responds to this perturbation by creating ordered periodic structures. We have used a system driven far from equilibrium to create structures that have subwavelength dimensions ...

Traditional formation pressure prediction methods all are based on the formation undercompaction mechanism and the prediction results are obviously low when predicting abnormally high pressure caused by compressional structure overpressure. To eliminate this problem, we propose a new formation pressure prediction ...

Regenerative medicine for repairing damaged body tissues has recently become critically important. Cell culture scaffolds are required for the control of cell attachment, proliferation, and differentiation in in vitro cell cultures. A new strategy to control cell adhesion, morphology, and proliferation was developed by culturing mouse osteoblast-like MC3T3-E1 cells on novel cell culture scaffolds ...

The specially designed adsorbent is one of the most important bases to achieve the expanded bed adsorption (EBA) process. The perfect adsorbents tend to be of small size, large pore and high density. In the present work a new kind of macroporous cellulose beads densified by high-density tungsten carbide were prepared through the method of water-in-oil suspension thermal ...

Porous polymer monoliths are considered to be one of the major breakthroughs in separation science. These materials are well known to be best suited for the separation of large molecules, specifically proteins, an observation most often explained by convective mass transfer and the absence of small pores in the polymer scaffold. However, this conception is not sufficient to explain the performance ...

The development of three-dimensional (3D) biomimetic scaffolds which provide an optimal environment for cells adhesion, proliferation and differentiation, and guide new tissue formation has been one of the major goals in tissue engineering. In this work, a processing technique has been developed to create 3D nanofibrous gelatin (NF-gelatin) scaffolds, which mimic both the ...

A series of surfactant-encapsulated polyoxometalates which have different compositions, shapes, and sizes, are able to self-assemble to the highly ordered honeycomb-structured macroporous films at the air/water interface without any extra moist airflow across the solution surface. The honeycomb film pores in the average diameter of 2-3 ?m are obtained, which are independent of ...

The permeability of macroporous karstic rocks is extremely difficult to measure in a laboratory setting due to flow- rate limitations of the measuring apparatus, and issues related to the maintaining and measuring the extremely small gradients needed to sustain Darcian flow regimes. High-resolution X-ray computed tomography (HRXCT) can provide digital reconstructions of porous ...

A simple synthesis pathway has been developed for the design of hierarchically structured spongy or spherical voids assembled meso-macroporous aluminosilicates with high tetrahedral aluminium content on the basis of the aqueous polymerisation of new stabilized alkoxy-bridged single molecular precursors. The intimate mixing of an aluminosilicate ester ...